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LOPEDIA

‘AND PHYSIOLOGY. |

THE

CYCLOP ADIA

ANATOMY anv PHYSIOLOGY.

EDITED BY
ROBERT B. TODD, M.D.

PROFESSOR OF PHYSIOLOGY AND OF GENERAL AND MORBID ANATOMY IN KING’S COLLEGE,
LONDON;

PHYSICIAN TO THE WESTERN DISPENSARY, AND TO THE ROYAL

INFIRMARY FOR CHILDREN, ETC. ETC.

LONDON:
SHERWOOD, GILBERT, AND PIPER,

PATERNOSTER-ROW.

ee

1836.

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ove ‘et

TAMARA, TO WA WOES 4

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4

ROBERT ADAMS, Ese.

Surgeon to the Richmond Hospital, and Lecturer on
Anatomy and Surgery, Dublin.

B. ALCOCK, M.B. Dublin.
W. P. ALISON, M.D. F.R.S.E.

Professor of the Institutes of Medicine in the Univer«
sity of Edinburgh, &c. ;

J. APJOHN, M.D. M.R.LA.

Professor of Chemistry to the Royal College of Sur-
- geons in Ireland. :

_ VICTOR AUDOUIN, M.D. Paris.

Professeur-Administrateur au Musee d’Histoire Na-
turelle.

_ B.G. BABINGTON, M.D. F.R.S.
_ THOMAS BELL, Ese. F.R.S.

a! Lecturer on Comparative Anatomy, Guy’s Hospital.

_ CHARLES BENSON, M.D. M.R.LA.

‘ Professor of Medicine to the Royal College of Sur-
_— geons, Ireland, &c.

_ JOHN BOSTOCK, M.D. V.P.R.S. London.
_ W.T. BRANDE, F.RS.

Professor of Chemistry to the Royal Institution, &c.

J. E. BRENAN, M.D. —
____ Lecturer on Anatomy and Physiology, Dublin.

G. BRESCHET, M.D.
____ Surgeon to the Hotel-Dieu, Paris.

JOHN COLDSTREAM, MLD. Leith.

on Member of the Wernerian Natural History Society of
. Edinburgh, &e. &e.

DAVID CRAIGIE, M.D. F.R.S.E.
_ Fellow of the RoyalCollege of Physicians, Edinburgh, &c.

J. BLIZARD CURLING, Esq.

a Assistant Surgeon to the London Hospital, and Lec-
_ turer on Morbid Anatomy.

G. P. DESHAYES, M.D. Paris.

A.T.S. DODD, Eso.

| ‘ Surgeon to the Infirmary, Chichester, and late Demon-
H. DUTROCHET, M.D.

_ Strator of Anatomy at Guy’s Hospital.
4 Member of the Institute of France, Paris.
V.F. EDWARDS, M.D. F.R:S.

_ Member of the Institute of France, Paris.

H. MILNE EDWARDS, M.D.

, _Professor of Natural History to the College of Henry
4Y., and to the Central School of Arts and Manu-
I -LULIC. Paris.

. D. GRAINGER, Ese.
s apy omy or Physiology at the Webb-
. E. GRANT, M.D. F.R.S.E.

OF ‘llow of the al College of Physicians, Edinburgh,
and Professor of Comparative Anatomy and Zoology in
the ‘London University. &e. &e. “i ¥

OHN HART, M.D. M.R.L.A.
Lecturer on Anatomy and Physiology, Dublin.

[ARSHALL HALL, M.D. F.RS. L. & E.

A ondaon.

4

CONTRIBUTORS.

ROBERT HARRISON, M.D.

Professor of Anatomy and Physiology to the Royal
College of Surgeons in Ireland.

ISID. GEOFFROY ST. HILAIRE, M.D.

Member of the Institute of France, Paris.

ARTHUR JACOB, M.D. M.R.I.A.

Professor of Anatomy and Physiology to the Royal
College of Surgeons in Ireland.

T. RYMER JONES, Esa.

Professor of Comparative Anatomy, in King’s College,
London.

F. KIERNAN, F.R.S. London.
R. KNOX, M.D. F.R.S.E. Edinburgh.
SAMUEL LANE, Eso.

Lecturer on Anatomy, St. George’s Hospital, London.

JOHN MALYN, Esq.

Surgeon to the Western Dispensary, and Lecturer on
Anatomy at the Westminster School of Medicine.

W.F. MONTGOMERY, M.D. M.R.LA.

Fellow and Professor of Midwifery to the King and
Queen’s College of Physicians in Ireland.

R. OWEN, F.R.S. London.

Professor of Comparative Anatomy and Physiology to
the Royal College of Surgeons in London.

RICHARD PARTRIDGE, Esa.

Professor of Descriptive and Surgical Anatomy inKing’s
College, London.

BENJAMIN PHILLIPS, F.R.S. London.
J.C. PRICHARD, M.D. F.R.S.

Corresponding Member of the Institute of France,
Member of the Royal Academy of Medicine of Paris,
and Senior Physician to the Bristol Infirmary.

W.H. PORTER, Esa.

Lecturer on Anatomy and Surgery, and Surgeon to
the Meath Hospital, Dublin.

RICHARD QUAIN, Esq.

Surgeon to the North London Hospital, and Pro-
fessor of Descriptive Anatomy inthe London University.

J. REID, M.D. Edinburgh.
HENRY SEARLE, Esa. London.
E.R. A. SERRES, M.D.

Physician to the Hospital of La Pitie, &c. &c. Paris.

W. SHARPEY, M.D. F.R.S.E.

Professor of Anatomy and Physiology in the London
University.

J. Y. SIMPSON, M.D. Edinburgh.
J. A. SYMONDS, M.D.

Physician to the Bristol General Hospital and Dispen-
sary, and Lecturer on Forensic Medicine at the Bristol
Medical School.

ALLEN THOMPSON, M.D.

Fellow of the Royal College of Surgeons, andLecturer
on the Institutions of Medicine, Edinburgh.

C. WHEATSTONE, Esa.

Professor of Natural Philosophy in King’s College, London,

REV. G. WILLIS, F.R.S. F.G.8. Cambridge.
R. WILLIS, M.D. London.
W. YARRELL, F.LS. F.ZS.

mig iy

Be, nor

CONTENTS OF THE FIRST VOLUME.

bdomen..+esseeeeee Dr. Todd....004 1
bsorption ........+. Dr. Bostock .... 20
c pphze ..seeseceee Dr. Coldstream .. 35
cids, Animal ...... W.T.Brande, Esq. 47
Nita eseeecececeess R. Owen, Esq. «. 47
dhesion ..++e+eeeee0 B. Phillips, Esq. . 49
lipocere coveccesee W.T. Brande, Esq. 55
2 Tissue ...... Dr. Craigie...... 56
a sccccececcceceoe Dr. Symonds ...- 64
fbino .......+++++++ Dr. Bostock...... 83
Mss siccnastee W.T. Brande, Esq. 88
nphibia covccceose 1. Bell, Esq. ...+ 90
me Kingdom .... Dr. Grant .....+ 107
imal...+++++-++e++ Dr. Willis ....0. 118
le, Region of the.. Dr. Brenan...... 147
cle, Joint of the .. Dr. Brenan...... 151
He-joinb Abnormal R. Adams, Esq. .. 154
dition of the ..
e plida.......+++++ Dr. Milne Edwards: 164
sevecesecseses R. Harrison, Esq. 178
Miles seccccccccss Dr. Hart.....000 187
achnida .......... Dr. Audouin .... 198
ae Dr. Hart...2.+.. 216
), Muscles of the.. Dr. Hart..,..... 219
otra eesccsscccecee Dr. Hart.....2.- 220
> Tesh Bee oeical b W.H. Porter, Esq. 226
Jonditions of ....
A eseeseseee R. Owen, Esq. .. 244
ulation ........ Dr. Todd......+. 246
PRIA... 00..00006 Dr. Alison .eeses 257
pees eeassovorces R, Owen, Esq. e+ 265
ae Dr. Benson ....2. 358
oo Dr. Hart........ 363
Breseesceeeeeee Dr. Harrison .... 364
tteseesesecees Dr, Benson ....+. 367

oy Se eeserrerece W.T. Brande, Esq. 374

~

>
‘
*

Bladder, Normal Ana- } The? Phretesk 2024
TOMY seceerecoecs
Bladder, Abnormal B. Phillips, Esq. .
Anatomy ....... .
Blood ....e0-+2ses0+ Dr. Milne Edwards
Blood, Morbid Condi- } Dr. Babington ..
tions of the ......
Bone, NormalAnatomy Dr. Benson ....+
Bone, Pathological ; W.H. Porter, Esq.
Conditions of,.....
Brachial Artery .... Dr. Hart......
Burs® Mucose ...... Dr. Brenan....-.
Carnivora ..sececces T. Bell, Esq. oe.
Carotid Artery ...... Dr. Hart ......
Cartilage......seeeee Dr. Benson oeeeee
Cavity .ccsccccccesce Drs Tod@.cccceis
Cellular Tissue ...... R.D.Grainger,Esq.
Cephalopoda ........ R. Owen, Esq. ..
Cerumen ....e+eee0++- W.T. Brande, Esq.
Cetacea .sseeesceeee Mons. F. Cuvier..
Cheiroptera........0. T. Bell, Esq. ...-
Chyliferous System .. Dr. Grant ......
Cicatrix ....++eee00. A. T. S. Dodd, Esq.
Cilia...seesseeeeeess Dr. Sharpey ....
Circulation ........++ Dr. Allen Thomson
Cirrhopoda ....++..- Dr. Coldstream ..
Cirronosis ...ccccees Dr. Todd..sessee
Conchifera ........++ M. Deshayes ....
Contractility .......+ Dr. Alison .se00.
Cranium ....e.++ee++ J. Malyn, Esq. ..
Cranium, Regions and pr. 2 ap SER
Muscles of the....
Crustacea ..++..+... Dr.Milne Edwards
Cyst .cccccccccceeess B. Phillips, Esq. .
Death ......seeeee00 Dr. Symonds ....
Analytical Index.:.ssccosssssseccesces

Page

376

389

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415

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438

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467
470
482
495
500
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517
562
562
594
600
602
606
638
683
694
694
716

724
746

750
787
791
809

2 | ABDOMEN.

ABDOMEN (in human anatomy.) In ex-
amining the human skeleton, we. notice that
from the apex of the thorax to the inferior out-
let of the pelvis, there exists one great oblong
excavation. The two superior fifths of this
cavity are separated from the remaining portion
in the entire subject by a musculo-tendinous
lamella, which, thrown into a vaulted form,
constitutes the partition between the cavity of
the thorax above and that of the abdomen below.
This latter cavity communicates inferiorly with
the space circumscribed by the ossa innominata,
denominated the cavity of the pelvis; nor is
there any natural line of demarcation between
the two cavities. The communication between
the two cavities is as free in the recent subject
as it isin the skeleton, and under various con-
ditions the contents of those cavities pass from
the one to the other. A plane extended hori-
zontally from the linea iliopectinea on one side
to the corresponding line on the other would
constitute an artificial floor to the cavity of the
abdomen, properly so called, and a limit be-
tween it and the pelvis; and this artificial divi-
sion of a cavity, naturally single, may be
useful in describing the positions of viscera, but
to understand the functions of the abdomen,
it will be expedient to consider that cavity
and the pelvis as one. Some anatomists ob-
ject to the use of the term cavity as applied
to the abdomen, because no cavity can be said
to exist, except in the skeleton or in the evisce-
rated subject; neither can there properly be
said to be a cavity of the thorax or of the cra-
~ nium, inasmuch as that cavity is obliterated so
long as the viscera are in a state of integrity.
I apprehend that the objection is hypercriti-
cal, as it must be evident that the cavity does
not become apparent till the viscera have been
removed ; nevertheless, it is perfectly correct
to say that it contains the viscera, nor is it in-
correct to make use of the expression “ anatomy
of the abdominal cavity,” to imply the anatomy
of its contents when in their natural position.
Hence, then, we derive a natural subdivision,
in treating the subject of this article, into two
heads: 1. the anatomy of the walls of the
abdomen ; and, 2.the anatomy of the cavity of
the abdomen.

I. Of the walls of the abdomen.—One of the
most striking differences between the abdomen
and the other great visceral cavities consists in
the small proportion of bone that exists in its
walls. The osseous boundaries of the abdomen
may be thus enumerated: superiorly, towards
the posterior and outer part, the false ribs;
posteriorly, the lumbar region of the spine,
which by its transverse processes affords strong
points for the attachment of muscles, and by
the bodies projects into the cavity, forming
an imperfect septum, slightly convex on its
anterior surface, and dividing the cavity into
two symmetrical portions. Inferiorly, the ale
of the ilia afford lateral] expansions, which
support some of the contents of the abdo-
men, and the pelvic brim completed behind
by the promontory of the sacrum, forms the
opening by which the cavity of the true pelvis
communicates with that of the abdomen.

Between the inferior margin of the thorax
and the superior margin of the false pelvis are
stretched muscular lamelle and tendinous ap-
oneuroses, the cingulum abdominis musculoso-
aponeuroticum of Albinus and Haller, which,
with integument, cellular membrane, &c. form
the anterior, lateral, and for the most part
the posterior walls of the abdomen, and circum-
scribe that space to which we have already
alluded under the name of the cavity of the
abdomen. .

The superior wall of the abdomen is the
diaphragm, and the inferior*wall of the abdo-
men, strictly so called, is formed by the ilia
and their muscles, and is open in the centre at
the superior outlet of the pelvis; but if the
abdominal and pelvic cavities be considered as
one, then those parts which fill up the inferior
outlet of the latter must be considered as
likewise constituting the inferior wall of the
former.

In the male adult the abdomen presents an
expanded convex surface anteriorly (the ante-
rior wall or proper abdominal region); poste-
riorly a broad surface not so extensive, situated
between the last ribs and the superior margin
of the pelvis, and divided into two by the
lumbar portion of the spine (the posterior wall,
the loins, or lumbar regions.) The anterior
and posterior walls are connected with each
other on the sides by two narrow regions (the
lateral walls or the flanks.)

The outline of the anterior wall or pro-
per abdominal region constitutes an oval, whose
long axis is vertical. The surface is generally
more or less convex during life, proportionally
with the degree of embonpoint of the indivi-
dual, and also according to the condition of the
diaphragm. After death, excepting in very fat
subjects, or where the intestines or peritoneal
cavity are much distended from any cause, this
surface is in a variable degree collapsed, and
more or less concave, but especially so in very
thin and emaciated subjects. There is a con-
stant adaptation in the condition of this surface
to that of the abdominal viscera, so that the
practitioner can in general argue pretty accu-
rately, from the state of the abdominal surface,
respecting that of the abdominal viscera, ex-
cept in cases where every thing is masked by a
superabundant deposition of adipose substance.
So close is the apposition of the abdominal wall
to the surfaces of the subjacent viscera, that in
some cases of extreme emaciation the peristaltic
movement of the intestinal canal is manifested
by the successive elevation and depression of
small portions of the walls corresponding to the
dilated and contracted portions of intestine.
This surface is divided into two equal and
symmetrical portions by a groove which exists
along the middle line, and which is chiefly ap-
parent in the two superior thirds. This groove

commences below the ensiform cartilage, where
there is a slight depression, denominated the —

scrobiculus cordis, (creux de l’estomac.) In
this line, about midway between the pubis and
xiphoid cartilage, is the round depression called
the umbilicus or navel. Just over the pubis there

is a prominent surface in both sexes covered

a

i hair; in the female it is much more pro-
ent than in the male, and is called the mons
eris. In subjects-where the muscular sys-

ian is well developed, there exists on each side

part of the chest to the pubis ; these convexities
dicate the situation of the recti muscles. In
stat es representing athletic men, the promi-
nence: occasioned by these muscles are gene-
tally very well shewn, and are divided by trans-
Verse superficial depressions into smaller qua-
dri | portions, generally three in number.
ternal to these prominences there is, in
lar muscular subjects, a fissure extending
2 the border of the chest, in a slightly
d course with external convexity, to a point

little to the inner side of the anterior superior
_ Spine of the ilium ; this fissure has internal to
the prominence from the recti muscles, and
! that from the broad muscles of the

‘ *

ABDOMEN.

a "a FEQ

ONY sngrawred by Teele Buriagh, SES Xa)

abdomen. Gerdy calls it the lateral groove or
furrow of the abdomen.* (See fig. 1.)

The posterior wall or the region of the loins,
(lumbar region, ) is in every way of less extent
than the anterior. Its vertical height is equal
to the distance between the last rib and the
margin of the ilium. It is continuous on the
sides with the flanks, and is divided along the
middle line by a groove, corresponding to the
lumbar spinous processes, into two symmetrical
portions, each of which forms a large and pro-
minent relief. Each relief corresponds to a
great muscular mass, which almost wholly oc-
cupies this region, and its prominence is greatest
when those muscles are in a state of contrac-
tion, as during the erect posture. Each relief
is coneave from above downwards, and in
a degree directly proportionate to the contrac-

* Gerdy, Anatomie des Formes Extérieures, p. 189.
The above engraving is reduced from the folio plates
which accompany this work.

4 | ABDOMEN.

tion of the muscles, insomuch that in some in-
dividuals the concavity is habitually very con-
siderable, as in those who carry burdens on the
head or in front of the body, in pregnant wo-
men, &e. (See fig.'2.) °°)... thi

The limit of this wall on each side is
indicated by a groove or fissure which passes
obliquely upwards and outwards towards the
ribs, and corresponds to the outer margin of
each relief, or that of the lumbar muscles ;
these lines also indicate the posterior limits
of the lateral walls of the abdomen, or the
flanks. Anteriorly the flank. of each side is
continuous with the anterior wall of the abdo-
men ; above it is limited by the margin of the
thorax, and below by the margin or crest of the
ilium. It is concave on its surface from above
downwards, (except in cases of great embon-
point, where the concavity is obliterated,) and
convex from before backwards. Gerdy remarks
that in subjects in which the muscles have a
considerable development, a relief is formed
just above the crista ilii by the broad muscles
of the abdomen at their insertion into. this
osseous border. Upon antique statues this
relief is in general made too prominent.

The anterior or proper abdominal region has
been subdivided into smaller compartments,
with a view to facilitating descriptions, patho-
logical or otherwise. This subdivision is com-
pletely arbitrary, and therefore some differences
will be found among the various anatomical
authors as to the precise limits of each region.
That which is here subjoined, however, appears
to be pretty generally agreed upon in this
country. Lines connecting particular points
drawn upon the surface, mark out these subdi-
visions, and if planes be supposed to be carried
from these lines horizontally backwards to the
posterior wall, the cavity of the abdomen will
thus be divided into segments, each of which
has its particular portion of the abdominal
viscera. It is an instructive exercise for the
student to practise himself in examining the
particular viscera which correspond to particu-
lar regions. We are thus enabled, as Blandin
has remarked,* to resolve the problem, “a
point of the surface of the abdomen being
wounded deeply in a given direction, to de-
termine what organs have been injured ; and
reciprocally, an organ having been wounded
in a particular part of the abdominal cavity
by a sharp instrument, which entered in a
given direction, to determine what part of
the abdominal walls must necessarily have
been injured.”+

The limits of these several regions or com-
partments may be thus indicated: { let a line
be drawn horizontally from the extremity of the
last rib on one side to the same point on the
other, and let another line parallel to the pre-
ceding be drawn between the two anterior
superior spinous processes of the ilium ; the

* Anatomie Topographique, p. 425.

+ The division of the surface of the abdomen into
regions is as old as Aristotle.

t See an engraving exhibiting these subdivisions,
in the article ABDOMEN of the CYCLOPAZDIA OF
PRACTICAL MEDICINE.

abdominal surface is thus divided into three
great regions, each of which is subdivided into
three by means ofa vertical line let fall on each
side from the anterior extremity of the seventh
or eighth rib to a point a little external to the
spine of the pubis. Nine regions are thus
marked out, the relations and boundaries of
which may be described as follows.

The superior region, or that above the first
horizontal line, is the Epigastrium, which name
it derives from its close relation to the stomach :
(m1, upon, over ; yaorne, the stomach.) The epi-
gastrium is bounded superiorly and laterally by
the margin of the thorax, and its inferior limit
is indicated by the transverse line. The verti-
cal lines subdivide it into two lateral regions,
each of which is bounded immediately above
by the lower margin of the thorax, beneath
which these regions extend in a direction up-
wards and. backwards: they are hence called
hypochondria (ve, under, yovdgos, cartilage).
Between the. hypochondria, is the proper
epigastric region, which at its superior part and
just below the xiphoid cartilage presents the
depression already alluded to under the name of
scrobiculus cordis (scrobiculus, the diminutive
of scrobs, a depression).

Immediately below the epigastrium, and
separated from it by the superior horizontal
line, is the umbilical region, which has its
name from the presence of the umbilicus in it.
This region is limited above and below by the
two horizontal lines, and is subdivided by the
intersection of the two vertical lines into three
regions : the lateral ones are the dwmbar regions,
so called from their correspondence with those
portions of the posterior abdominal wall which
bear the same name ; and the middle one is the
proper umbilical region.

Between the inferior horizontal line and the
margin of the pelvis, is the hypogastrium, (vo,
beneath, yaorne, the stomach). This region is li-
mited below in the centre by the pubis, and on
each side it communicates with the upper part
of the thigh. It is subdivided into the iliac
regions on each side, and the proper hypo-
gastric or pubic region in the centre. The two
former constitute the upper or abdominal
portion of the great region of the groin, which
is completed inferiorly by the upper part of the
anterior surface of the thigh. ese regions
afford peculiar interest to the surgical ana-
tomist, in consequence of the occurrence in
them of the most common forms of hernia.*
(See Groin, REGION OF THE.)

The structures which enter into the com-
position of the abdominal parietes, or their
elements, (as the term has been lately applied,)
are—1. the skin: 2. the subcutaneous tissue
or superficial fascia: 8. muscles and their
aponeurotic expansions: 4. a particular fibrous
expansion, or fascia: 5. a thin and filamen-
tous cellular tissue, which separates the fascia
just named from the sixth element: 6. the peri-
toneum, which, however, is not to be foundinthe _
composition of all the walls of the abdomen. _

* Velpeau applies the term zone to the primary
regions included between the horizontal lines.—
Anat. Chirurg. t, ii.

he ABDOMEN.

: In and between these several structures ramify
E the various arteries, veins, lymphatics, and
nerves, which constitute the vascular and ner-
; vous supply to the abdominal parietes.

1. The skin on the anterior and lateral parts
of the abdomen is thin and smooth, and in
some parts covered with hairs, as along the
middle line, especially below the umbilicus and
over the pubic region. Along the median line
the cutaneous follicles are largely developed,
and during pregnancy an increased secretion of
pigmentum is said to take place, producing
a brownish colour of the skin in these regions.
In women who have borne children, the
skin becomes wrinkled to a considerable de-
gree, and the epidermis exhibits, as Winslow
__ has remarked, a great number of lozenge-
shaped spaces disposed in a reticular manner.*
i n the epigastric region the skin is much
_ -more sensitive during life than in the other
parts of the abdomen, and with some persons
5 ggg with the stomach in a remarkable

, so that pressure on it even in the
healthy state gaan a degree of pain or un-
easiness in that organ, or even a tendency to
nausea. In the umbilical region we observe a
depression, the floor of which is more or less
elevated in the centre. This depression is de-
nominated the navel or umbilicus, (the dimi-
nutive of uwmbo, a nob or button.) It is
produced by the firm adhesion of the skin to
the subjacent structures, its true nature being
that of a cicatrix, occupying the site of a
former perforation through which the umbilical
arteries and veins and the urachus passed in
maintaining the circulation between the foetus
and placenta. In very fat persons, the depth
of the depression is often very much increased
by reason of the great thickness of the abdomi-
nal parietes, and in some instances its form
assumes that ofa slit, and sometimes, instead
of a depression, there is a greater or Jess pro-
minence of the integument.

In the lumbar region the skin is thicker and
_. firmer than in the others; and we generally
_ find it ina state of congestion after death, in
consequence of the position of the body.
2. The subcutaneous cellular tissue on the

anterior surface of the abdomen has obtained
especial attention from anatomists, particularly
_ that portion of it which is found in the hypo-
gastric regions, It is denominated the superficial
___fascia,t and is merely an expanse of cellular
tissue possessing the same general characters

* Winslow’s Anatomy, by Douglas, v. ii. p. 160.
+ The application of the term fascia to the sub-
_ entaneous cellular investment in various parts of the
body has occasioned no small degree of confusion
among anatomists. A singular degree of confusion
_ exists in Velpeau’s description of this fascia: he
_____ Observes in one place that the deep layers of the
___ ‘subcutaneous cellular tissue constitute the super-
_ ficial fascia, and in the next page states that <* the
_ superficial fascia is nothing else than the cellular
_ tissue condensed, whose laminz strongly applied
one against the other, are ultimately reduced to
_ somewhat of the aponeurotic form.” I shall adhere
to this latter definition, and consider superficial
fe as synonymous with subcutaneous cellular
tissue.—Velpeau Anat. Chirurg. vol, ii. p. 4 and 5,

*3

as that which is found in all other parts of the
body ; it is continued upwards over the thorax,
laterally into the region of the back, inferiorly
along the thighs, and into the scrotum. It varies
in thickness according to the quantity of fat
which is deposited in its cells ;* in some in-
stances it has been known to possess a thick-
ness of three inches. Thin but muscular subjects
afford the best examples from which to study
the superfical fascia of the abdomen : in such
subjects we find it in general of a much denser
character than in others, very strong and elastic
and easily divisible into lamine, produced,
no doubt, by the pressure which it experiences
from the weight of the abdominal viscera, and
the constant attrition occasioned by the action
of the abdominal muscles. In the iliac region,
immediately above Poupart’s ligament, the
density of this fascia is most conspicuous.
Here some have regarded it as a fibro-cellular
membrane ; but the opaque bands which give
it a fibrous appearance are merely the walls of
the membranous cells rendered thicker and
denser than they are in other parts. I cannot
agree with Beclard+ that it presents almost all
the characters of an aponeurosis, inasmuch as
it differs from an aponeurosis in wanting the
shining and regular surface, and in possessing
a degree of elasticity which never belongs to
aponeurotic expansions. The elasticity of the
superficial fascia is remarkable, and is by some
compared to the elastic expansion over the
abdomen of the larger quadrupeds ;{ the
comparison, however, is inaccurate, inasmuch
as they are two distinct tissues, the former
being cellular, and the latter the aponeurosis
of the oblique muscles, which in some degree
partakes of the properties of the yellow elastic
fibrous tissue (tissu jaune ).

Inferiorly the superficial fascia moves freely
over Poupart’s ligament, and is continued over
the thigh (see Groin, Recion or THE). Along
the middle line it is very adherent to the sub-
jacent aponeurotic structure (the linea alba)
as well as to the skin,—a fact which may be
remarked of the subcutaneous cellular tissue in
other parts of the body, and which was long ago
noticed by Bordeu, when he observed that the
cellular tissue is constricted (etranglée ) in all its
median portion, and that its cells (ballons ou
pouches ) ave closed over the axis of the body.
When this superficial fascia is dissected off, a
very thin layer of cellular membrane, perfectly
diaphanous, is found to adhere to the subjacent
aponeurotic expansion. This will be found
particularly adherent over Poupart’s ligament,
and is that which is referred to by some ana-
tomists (as Manec, Cloquet, &c.,) as a deep
process of the superficial fascia which adheres
to Poupart’s ligament, and so forms a super-
ficial septum between the abdomen and thigh.
To see this layer the superficial lamina should
be raised by commencing the dissection of it

* Cloquet says it is, as it were, decomposed by
the deposition of fat.—Recherches Anat. sur les
Hernies de l’Abdomen, p. ll.

+ Dict. de Médecine, art. abdomen.

t Vid. Blandin, Anat. Topog. ;

B

4*

below and carrying it upwards; the expansion
will then appear to arise from Poupart’s liga~
ment, and spread over the subjacent aponeuro-
sis. In some subjects it is so thin as to appear
to be little more than the proper cellular cover-
ing of the muscle and its aponeurosis, but
in others it assumes a considerable degree of
density. It may be called the deep layer of
the superficial fascia ; it deserves attention from
the fact that the femoral hernia, in its ascent on
the abdomen, lies between it and the super-
ficial layer. It is to this fascia that Scarpa
must allude under the name of “ aponeurotic
web of the muscle of the fascia lata,” and
hence some have called it Scarpa’s fascia.*
The whole of the superficial fascia has been
called Camper’s fascia, because it was first
fully described by that writer.+

On the posterior wall of the abdomen, in the
lumbar regions, the cellular tissue is more
abundant and more lax; here we frequently
find it infiltrated with serous fluid, in conse-
quence of the usual supine posture of the body
after death. It is continuous above with the
subcutaneous tissue in the dorsal region, and
below with that in the gluteal regions. It,
too, is firmly adherent along the middle line to
the lumbar spine anteriorly, and to the skin
posteriorly.

3. Muscles and aponeuroses.—The abdo-
minal parietes owe their thickness chiefly to
the muscular lamelle and the aponeurotic ex-
pansions, which enter into their composition.
In the anterior and lateral walls we find on
each side five pairs of muscles, of which four
are constantly present. These are, 1, M. obli-
quus externus; 2, obliquus internus; 3, trans-
versalis; 4, rectus abdominis ; 5, pyramidalis,
which last is frequently absent.

1. Obliquus externus. (Obliquus descen-
dens ; costo-abdominal ; ilio-pubi-costo-abdo=
minal. )

When the superficial fascia covering the an-
terior and lateral surfaces of the abdomen has
been dissected away, this muscle is brought into
view. It consists of a flat muscular portion,
situated superiorly and posteriorly, and of a
tendinous or aponeurotic !amella anteriorly and
inferiorly, but which is largest and strongest in
the latter situation.

The muscular portion of the external oblique
is attached by separate fasciculi to the external
surfaces of the eight inferior ribs, from the
fifth to the twelfth inclusive. These fasciculi
indigitate at their attachment with similar
ones, of the serratus magnus, from the fifth
to the ninth inclusive, and of the latissimus
dorsi from the tenth to the twelfth. From
these points of attachment, described by most
English anatomists as the origin of the
muscle, the fibres pass obliquely downwards
and forwards, with different degrees of ob-
liquity, the middle fibres being the most ob-

* Vid. Scarpa on Hernia, by Wishart, p. 22;
also Todd on Hernia, Dub. Hosp. Reports, vol. i.
p. 246; and Flood’s plates of Inguinal and Femoral
Hernia.

¢ Camper, Icones Herniarum, p. 11.

ABDOMEN.

lique, the superior taking a direction nearly
horizontally inwards, and the posterior ones
passing nearly vertically downwards. The an-
terior and middle fibres are inserted into the
outer convex border of the aponeurotic lamella
of the muscle, but the posterior are inserted into
the outer lip of the two anterior thirds of the
crista of the ilium by short tendinous fibres.
The fibres of this muscle vary considerably in
length, those which are highest up being the
shortest, the middle ones the longest, and next
in length the posterior fibres. The aponeurotic
lamella of the external oblique muscle is found
on the anterior part of the abdomen, both su-
periorly and inferiorly. In the former situa-
tion the aponeurosis is extremely thin and
weak ; it is transparent, so that the upper
extremity of the rectus muscle which it covers
is visible through it. This, too, is the narrow-
est portion of the aponeurosis, which increases
in breadth, strength, and thickness as it de-
scends. The aponeurosis, like the muscular
portion, consists of a series of fibres, for the
most part inclined obliquely downwards and
inwards, excepting the superior ones, whose
direction is horizontal. At several places these
fibres are separated from each other so as to
allow the subjacent muscle to be seen through
the interval. At various parts the tendon is
perforated by vascular apertures, which are oc-
casionally so enlarged as to admit little peri-
toneal prolongations to pass through them.
Along the middle line, from the ensiform car
tilage to the symphysis pubis, the aponeurosis
forms an interlacement with its fellow of the
opposite side, and this interlacement with that
of the subjacent’ aponeuroses constitutes the
tendinous line called linea alba, which, as
Velpeau observes, may be regarded as the
centre in which all the fibrous elements of the
abdomen terminate. Just above the symphysis
pubis, the decussating fibres are not inter-
mixed in the same manner as in other parts of
the linea alba: there the bundle of one side
crosses anteriorly or posteriorly to that of the
other, without any union of fibres, to be in-
serted into the pubis of the side opposite to
that from which it came.

A little above and external to the pubis, a
separation of the fibres of the tendon of the
obliquus externus takes place, leaving an
opening which is denominated the external
abdominal ring, through which the rounded
bundle composed of the spermatic vessels and
duct (the spermatic cord) passes in the male,
and the round ligament of the uterus in the
female. The aponeurotic fibres which form
the immediate boundaries of this opening are
termed the pillars of the ring, of which one is —
superior, internal, and anterior, the other is in-
ferior, external, and posterior, and passes behind
the cord. External and inferior to this openi
we observe that the aponeurosis of the external
oblique muscle is extended from the pubis to
the anterior superior spine of the ilium. On
the pubic side, the fibres, which are the same
that form the inferior pillar of the ring, are in-
serted into the spine of the pubis, and being

' ABDOMEN. 5

‘reflected backwards, outwards, and a little
upwards, they are likewise inserted into the
linea ilio-pectinea, which commences at the
spine of the pubis. The lower margin of the
tendon is thus folded back a little as it arches
over the excavation between the pubis and
ilium, so as to present towards the abdomen a
slight channel-like excavation, which affords
origin to the muscular fibres of the internal
: oblique as well as to those of the transver-
' salis, whilst it has the ap nce of a rounded
_ ligamentous cord sheratids thie thigh. In this
manner is formed Poupart’s ligament, which,
contrary to what its usual name denotes, is
not a distinct ligamentous cord, but the in-
ferior margin of the external oblique stretched
from pubis to ilium, and folded a little upon
itself. By its superior margin it is continuous
with the fibres of the tendon of the external
_ oblique, which fall obliquely upon it ; by its in-
| __ ferior margin it is intimately connected with the
fascia lata of the thigh ; externally it is inserted
into the anterior superior spine of the ilium ; and
by its pubic extremity it has three attachments,
1. to the body of the pubis; 2. to the spine
- of the same; and 3. to the linea ilio-pectinea,
' constituting what has been called Gimbernat’s
_ ligament, which has a sharp slightly crescentic
margin directed backwards and outwards to-
wards the femoral vessels.* (See Groin,
_ Recion of THe.)
__ The external abdominal ring is a triangular
_ Opening, situated obliquely ; the superior angle
being directed upwards and outwards, and its
_ base, represented by a line uniting the pubic
insertions of the two pillars, resting upon the
_ pubis. The superior angle is formed evidently
by the separation of the fibres of the aponeu-
-rosis, the primitive direction of which is the same
as that of a perpendicular from the apex to the
base of the triangle, viz. downwards and in-
‘wards, (sacrad and pubad.) This separation,
however, is strengthened, and the angle round-
ed by some tendinous filtres which inter-
Sect the oblique ones nearly at a right angle,
‘arising as a cord of variable thickness from
Poupart’s ligament, and passing upwards and
‘Imwards over the apex of the ring, gradually
parating into several tendinous fibres. These
fibres are sometimes very strong, at other
‘times very feeble and scarcely perceptible ;
be t it rarely, if ever, happens that they are
completely absent; they have been termed
intercolumnal bands. 1 have seen them so
Strong that a could be distinctly dissected
off the external oblique aponeurosis, like a
Separate tendinous expansion; but most fre-
uently they are so united to the aponeurosis
is to render it impossible to remove them
ithout injury to it. These fibres are evi-
ntly intended, as Scarpa expresses it, “ to
ix the limits of the inguinal ring, and to
yppose the further divergence of the tendi-
nous pillars towards the side.” They are
_ * The terms crural arch, and ligament of Fallopius,
are also used synonymously with Pocpave ten.
ent. pte calls it bandelette ilio-pubienne du

OR RRS oe wer

PE BR Ih Gh AF ai Be ae

. few Babe

equally met.with, although not nearly so much
developed, in women and children as in men;
and Mr. Lawrence asserts that in old herniz
they are particularly strong. I cannot confirm
this remark from my own observation, as in
my dissections of old hernia, I have not
found them particularly developed; nor is it con-
sistent with the general result of pressure from
within on tendinous fibres to believe that such

ressure would produce an increase of deve-
opment in them.

The size of the external abdominal ring is
greatest in the male subject, but here it varies
considerably, sometimes closely embracing
the cord as it passes through it, and at others
appearing much too large for it. In the male
the parts which pass through it are the sper-
matic cord, enveloped in its proper tunic, and
in one of condensed cellular membrane pro-
longed from the fascia transversalis, a branch
of the genito-crural nerve, the cremaster mus-
cle, the cremasteric artery, and the spermaticus
superficialis nerve. In the female, we find
the round ligament of the uterus, covered and
accompanied by similar parts, excepting the
cremaster. From the margin of the external
abdominal ring, a cellular expansion or fascia
is carried over the cord or round ligament,
and has been denominated fuscia spermatica.
This fascia consequently forms a covering of
any hernia that may be protruded through the
external ring; and, accordingly, in old herniz
we find it greatly thickened. Its formation
is simply in accordance with what we find oc-
curring in all parts of the body, viz. that when
any part passes through an opening in a fibrous
membrane, it carries with it a cellular expan-
sion from the margin of that opening. This
we observe in the passage of the vena cava
through the diaphragm, of the urethra through
the triangular ligament or deep perineal fascia.
This view confirms the opinion of Sir A.
Cooper, that this fascia is a production from
the margin of the ring itself.

The external oblique muscle is covered in
all its extent by the superficial fascia ; its costal
margin is related to the serratus magnus, and to
the latissimus dorsi, with which muscle it is also
in close relation by its posterior margin, being
sometimes slightly overlapped by the anterior
margin of the latissimus, but at others separated
from that muscle by a triangular interval
through which the fibres of the obliquus inter-
nus appear: inferiorly the fascia lata of the
thigh is related to the margin of the external
oblique muscle, both as it covers the glutei, and
as it lies in front of the thigh. Along the
middle line the aponeuroses of opposite sides
meet at the linea alba, and superiorly the mus-
cular fibres are related to and sometimes con-
nected by a fleshy slip with those of the pecto-
ralis major, and the aponeurosis is continuous
with that of the same muscle.* When the ex-

* «« Byits position, the direction of its fibres, and
the short distance to which its fleshy portion extends
forwards, the external oblique corresponds so much
to the external intercostals, that one is led to say
that it represents them in the abdomen.”—Meckel.

6 ABDOMEN.

ternal oblique is removed from its osseous at-
tachments, and raised inwards, it is found to
cover the internal oblique, with part of the ten-
don of which it is ultimately united as the two
tendons approach the linea alba.
2. Obliquus internus (obliquus ascendens,
ilio-abdominal, ilio-lumbo-costi-abdominal ) is
smaller than the preceding muscle, which it
resembles in shape and general characters. The
direction of its fibres, however, is opposite,
Inasmuch as the fibres of the two muscles
decussate with each other, thus adding con-
siderably to the strength of the abdominal wall,
and forming a great protection against visceral
protrusions. The external attachments (or, as
systematic writers call it, the origin of the mus-
cle) is 1. by short fleshy fibres to the tendinous
expansion covering the lumbar mass of muscles,
called fascia lumborum, which is formed by
the posterior lamina of the tendon of the trans-
versalis abdominis: 2. to the two anterior
thirds of the middle portion of the crista ilii,
between the external oblique and the transver-
salis as far forwards as the anterior superior
spine: 3. to the groove in the upper or abdo-
minal surface of Poupart’s ligament for about
its external third. The superior fibres pass
upwards and inwards, and are inserted b
fleshy slips into the cartilages of the twelfth, ele-
venth, and tenth ribs, in the intervals between
which they are either separated from the inter-
costal muscles by a fibrous intersection, or con-
founded with them, and by a tendinous aponeu-
rosis into the cartilages of the ninth, eighth, and
seventh ribs as well as into the xiphoid cartilage.
Lower down, the fibres which arise from the
crista ilii, as well as those from Poupart’s liga-
ment, pass inwards, the superior obliquely
upwards and inwards, the inferior more hori-
zontally, and the lowest fibres inclining a little
downwards, and are all inserted, like those of
the obliquus externus into the outer convex
margin of an aponeurotic expansion, which goes
to be inserted along the middle line. This ten-
don passes inwards for a short distance, nearly
as far as the outer margin of the rectus muscle,
asa single lamina. Along this margin, and as
low down as the inferior fourth of the rectus
muscle, the tendon divides into two lamine,
of which the anterior adheres to the posterior
surface of the tendon of the external oblique,
and the posterior to the subjacent tendon of the
‘transversalis, both laminz going to be inserted
into the ensiform cartilage and linea alba, the
one in front, the other behind, the rectus muscle.
(See fig. 4, a.) For a distance, however, corres-
ponding to the inferior fourth of the rectus
muscle, the tendon of the obliquus internus re-
mains undivided, and does not adhere to that of
the obliquus externus. It, however, is united,
although not inseparably, to the tendon of the
transversalis, and both go in front of the rectus
to be inserted into the linea alba and pubis:
these tendons are here called by some the con-
joined tendons. Along the line at which the
tendon of the obliquus internus divides into two
lamin, the aponeurosis of the obliquus externus

and that of the transversalis adhere to it more
closely than they do externally to that line, and
thus a thickened portion of the abdominal
aponeurosis is formed, taking the course of the
outer margin of the rectus muscle: this line is
called the linea semilunaris, and is that in which
the operation of paracentesis abdominis used
formerly to be practised. .

The inferior margin of the obliquus internus
is deserving of particular attention. The in-
ferior fibres attached to the external third of
Poupart’s ligament in the groove formed in it
pass transversely inwards and parallel to the
ligament, crossing over the spermatic cord, to
be inserted into the pubis. Here the muscle is
confounded with the inferior fibres of the sub-

jacent one, the transversalis ; so that it is not

only difficult to say which muscle passes low-
est down, but it is difficult,and often impossible,
to separate the two muscles. Hence the lower
margins of the fleshy fibres as well as of the apo-
neuroses of these two muscles are constantly
spoken of conjointly ; however, I have several
times succeeded in separating them distinctly,
and Iam decidedly of opinion that the apo-
neurosis of the obliquus internus seldom or
never descends so low down as that of the trans-
versalis. The lowest of the fibres of the obliquus
internus are sometimes observed to separate a
little from the others, so as, instead of a directly
transverse, to assume a course slightly curved
with the concavity upwards and a little outwards,
lying in front of the cord ; in some cases fibres
of this kind are observed to lie in front of the
spermatic cord, and to descend much lower
down, taking of course a much more curved
direction, still attached on the outside to Pou-
part’s ligament, and on the inside to the pubis,
so that a series of curved fibres are thus found
to adhere to the anterior surface of the cord and
of the tunica vaginalis, exhibiting an equal num-
ber of reversed arches. But this disposition is
rarely seen in its most highly developed state,
excepting where some tumour has been con-
nected with the cord or testicle, as hernia,
hydrocele, &c.

This arched arrangement of muscular fibres _
in connection with the spermatic cord and —
tunica vaginalis testis constitutes the Cremas-
ter muscle (xgeuaw, suspendo,) the great tenuity
of which in the natural state of the parts has ren-
dered it difficult to determine its precise attach-
ments, and consequently has given rise to the
great discrepancy which is observable between
the descriptions of different writers. When
this muscle is examined in a case of old hernia
or hydrocele, it is found, as Scarpa originally
described it,to consist of two bundles ; the first,
external to the cord which arises from Pa |
ligament along with the internal oblique, follows
the course of the spermatic cord, which it ac-
companies through the external abdominal ring,
sending at intervals fibres arching in front of
the cord to join a similar bundle on the inner
side, as may be seen in the accompanying en-
graving from a plate in Sir A. Cooper’s work
on the testis (fig. 3). Inferiorly, this bundle, a

—) e

_ ABDOMEN. ’

c, the internal oblique ; e, the descending fibres; f,
point of insertion into the pubis; h, one of the re-
versed arches; d, conjoined tendons; a, rectus
muscle.

good deal diminished in size, crosses over the
inferior and anterior portion of the tunica vagi-
nalis testis, and begins to ascend along the inner
# side of the testicle and cord, keeping more pos-
_ __ teriorly : this constitutes the second bundle; it
____ gradually increases in size as it ascends by re-

ceiving the transverse fibres from the bundle of
the opposite side, and it is inserted, sometimes
___ by adistinct tendon, into the pubis near its spine.

In some cases I have totally failed, even after
the most careful dissection, in detecting a conti-
nuity by muscular fibre between these two bun-
' dies, insomuch as to lead me to imagine that
__ they may be connected by a very condensed cel-
ular tissue or thin aponeurotic lamella after the
manner of the digastric muscles. In general the
external bundle is larger than the internal, but
Cloquet has seen the reverse three times; and on
referring to my notes, I find I have seen two

p) instances in which the internal bundle exceeded

the external in size.
__ Many anatomists have noticed only the ex-
_ ternal bundle of the cremaster, and altogether

overlooked its reversed arches, which is not to
_ be wondered at when we remember that even
_ where the lateral bundles are strong and well
merpped, the arched fibres are sometimes pale
and thin. However, the description now
_ given is pretty generally admitted as the true
One, and is sanctioned by such observers as
_ Searpa, Cloquet, Cooper, Velpeau, and I may

‘ add that I have seen this arrangement in cases
> where both testicle and cord were healthy. It
____ would appear that its formation is effected by
___ the testicle in its descent, for before that takes
place the muscle does not exist; at least such is
the result of Cloquet’s observations on a con-
siderable number of foetuses before, during, and
after the descent of this organ. Before the de-
scent the gubernaculum testis occupies the
inguinal canal, and is covered by the fibres of
the internal oblique, which adhere to it; when

.

the gubernaculum is drawn down, these -fibres
descend with it, forming a series of reversed
arches.

In some female subjects we see an arrange-
ment of the inferior fibres of the internal oblique
as they cross over the round ligament, which
resemble a rudimentary state of the cremaster
muscle.

A thin layer of cellular tissue, sometimes
containing a small quantity of fat, is interposed
between the anterior surface of the obliquus
internus and the obliquus externus. At the infe-
rior edge of the obliquus internus the spermatic
cord is seen emerging from the abdomen and
passing obliquely inwards and a little down-
wards tothe external abdominal ring. Hereit lies _
in a groove or channel, called the inguinal canal,
which extends from the point at which the
spermatic cord emerges from the abdomen, (the
opening in the fascia transversalis called in-
ternal abdominal ring) to the external abdo-
minal ring. This canal is bounded or covered
anteriorly by the tendon of the obliquus
externus; posteriorly by the fascia trans-
versalis and some fibres of the tendon of the
transversalis muscle towards the inner side;
superiorly by the margin of the obliquus in-
ternus and transversalis muscles ; and inferiorly
by the groove of Poupart’s ligament.* (A full
description of this canal will be found in the
article Groin, REGION OF THE.)

3. Transversalis (lumbo-abdominal, lumbo-
ili-abdominal). This muscle is immediately
under cover of the obliquus internus ; its name
is derived from the transverse direction of its
fibres. In its general character it resembles
the obliqui, being like them a muscular lamella,
inserted into a tendinous expansion, which
again is inserted into the linea alba. Supe-
riorly the fleshy fibres of this muscle are attach-
ed by distinct bundles to the internal surface
of the cartilages of the ribs forming the lower
margin of the thorax, where these bundles in-
digitate with those of the diaphragm: 2dly, in
the interval between the last rib and the crista

* «« The obliquus internus corresponds to the in-
ternal intercostals by the direction of its fibres,
by its being situated under cover of the obliquus
externus, and because its fleshy fibres extend mach
further forwards than those of the last-named mus-
cle.””— Meckel.

8 ABDOMEN.

ilii, the fibres arise from a tendinous lamella,
which itself is trifoliate in its origin. This ten-
don is found as an undivided lamella between
the outer margin of the quadratus lamborum and
the commencement of the fleshy fibres of the
muscle, extending vertically from the last rib
to the cristailii. ( Fig.4,l.) The three lamine
of which this tendon is composed arise from
different portions of the vertebre in the lumbar
region of the spine; the posterior, which is
thick and strong, and is commonly called
JSuscia lumborum, arises from the extremities
of the spinous processes, and covers the lum-
bar mass of muscles. ( Fig. 4,g.) The mid-
dle, which is weak, is attached to the apices of
the transverse processes ; it lies in front of the
lumbar mass and behind the quadratus lumbo-
rum (fig. 4, h); and the anterior arises from the
pedicles which connect the transverse processes
to the bodies of the vertebrae, and covers the
quadratus lumborum muscle in front (fig. 4,
J). Inferiorly, the transversalis muscle at-
taches itself to the inner lip of the crista ilii
for its three anterior fourths, and to the ex-
ternal third or half of Poupart’s ligament, cor-
responding to the attachments of the obliquus
internus. The fleshy fibres of the muscle pass
from these several points of attachment trans-
versely inwards, the middle being the longest,
and the superior the shortest, and are in-
serted into the outer convex margin* of a
tendinous aponeurosis, which extends to the
linea alba. This aponeurosis is intimately
connected with the posterior division of that
of the obliquus internus for an extent corre-
sponding to the three superior fourths of
the rectus muscle, behind which both pass to
be inserted into the ensiform cartilage and
linea alba, (fig. 4, a,) forming the posterior
wall of the sheath of the rectus. Inferiorly, as
we have already remarked, these conjoined
tendons go together in front of the rectus, and
are inserted into the inferior fourth of the linea
alba and into the pubis. At the inner extre-
mity of the ingtinal canal, it will be seen by
carefully raising up the spermatic cord, that
this union of the tendons of these two muscles
ceases, and we can trace the fibres of the trans-
versalis tendon passing down in a curved direc-
tion, more curved as they are more external,
and insinuating themselves behind the cord to
be inserted into Gimbernat’s and Poupart’s
ligament for about its external third or fourth.
This mode of insertion of the transversalis ten-
don was first-described by Sir Astley Cooper,+
and these fibres were by him called the folded
Jibres of the transversalis. They adhere to the
subjacent fascia, (fascia transversalis,) and add
to the strength of the inner portion of the pos-
terior wall of the inguinal canal. They cor-
respond, in a great measure, to the external
abdominal ring, and may be counted as one of
the obstacles provided against the direct descent
of a hernia.
Such is unquestionably the usual mode of

* This margin forms the linea semilunaris of
Spigelius.
+ Cooper on the Testicle, p. 35.

insertion of the tendon of the transversalis
muscle; but Mr. Guthrie has lately called the
attention of anatomists to a variety which it
is important to know, although it cannot be —
of frequent occurrence. In this variety the
spermatic cord appears to pass through a slit in
the inferior margin of the transversalis muscle,
so that a bundle of muscle passes behind as
well as before the cord ; the posterior one end-
ing in tendinous fibres, which, like the folded
fibres above described, are inserted into Pou-
part’s ligament.* It is very generally believed
that the inferior fibres of this muscle contribute,
as well as those of the obliquus internus, to
form the cremaster. The two muscles are so
closely connected externally by their inferior
margins, that it is natural to suppose that both
do send fibres to the cremaster. Sir Astley
Cooper expresses the relation of the cremaster
to these two muscles in the clearest way, when
he says that it arises from Poupart’s ligament
within the inguinal canal, and there blends with
some of the fibres of both these muscles.F _

A thin layer of cellular tissue covers the
transversalis muscle, and separates it from the
obliquus internus. At its superior margin it
is intimately related to the diaphragm, and
some of its fibres seem to be continuous with
it: posteriorly, by the triple partition of its
tendon, it ensheaths the lumbar muscles, and it
lies upon the fascia transversalis, which, witha
layer of cellular tissue, separates it from the
peritoneum. f ;

4. Rectus abdominis (sterno-pubien). After
the superficial fascia has been removed so as
to expose the aponeurosis of the external ob-
lique, the recti muscles are seen on either side
of the middle line covered by this aponeurosis,
which it is necessary to slit up in order to ex-
pose the muscles. The rectus owes its name
to the perpendicular course of its fibres, which
pass from the pubis to the thorax, nearly
parallel to the middle line. It is long and
narrow ; however, its breadth increases as it
advances upwards, and as it increases in breadth
it diminishes in thickness. At the pubis the
muscle has its most fixed point of attachment,
whence it is generally said to have its origin
there: it arises by a short tendon from the
symphysis of the pubis; this tendon is very
narrow at its origin, but soon expands, and
unites with the muscular fibres, which pass
vertically upwards to the lower margin of
the thorax, where the muscle is considerably
increased in breadth, and divides into three
portions; the first or internal one is inserted
into the costoxiphoid ligament and cartilage
of the seventh rib; the middle, larger than
the preceding, into the cartilage of the sixth
rib at its inferior edge and anterior surface;

* Guthrie on Inguinal and Femoral Hernia, pp.
11, 12, 13, 4to. Lond. 1833. "ts
t Op. cit. p. 38. J
{ ‘* The transversalis corresponds, by the direction
of its fibres, to the ‘ tri

situation, by the attachment of its external edge to

the internal surface of the ribs, and by that of its —

internal edge to the sternum and linea alba.”—
Mechel. Aes

ularis sterni ;’ also, by its —

ABDOMEN. 9

rand the external, the largest of the three,
into the inferior edge of the cartilage of the
fifth rib. This muscle is remarkable for its
tendinous intersections, which cut the fibres at
right angles, and are called linee transverse ;*
they vary in number from three to five, and are
always more numerous above than below the
umbilicus. In general there is one on a level
with the umbilicus; the superior one being
about an inch below the superior attachment of
the muscle, and a third midway between these

. two: when a fourth and a fifth exist, they are

below the umbilicus. They adhere to the an-
terior wall of the sheath closely, and but very
slightly or not at all to the posterior. Some-
times the intersection does not go completely
through the thickness of the muscle so as to
appear on its posterior surface, and thus the
rior fibres are longer than the anterior;

ut as Bichat remarks, it never happens that
any of the muscular fibres pass from one extre-
mity of the muscle to the other without
uniting at least one of these intersections.
Sometimes, too, the intersection does not go
through the breadth of the muscle, and this is
generally the case with that below the umbili-
cus. The effect of these intersections is to
convert the muscle into so many distinct bellies,
each of which has its proper action, and is, as
Beclard asserts, provided with a separate

_ —merve.t

The rectus muscle is enveloped in a fibrous
sheath, the mode of formation of which the
reader must have collected from the description
of the oblique muscles. The anterior wall of
this sheath is formed by the aponeurosis of the
external oblique alone over the chest, and by the
Same aponeurosis and the anterior layer of that of
the internal oblique, from the xiphoid cartilage
to the inferior fourth of the muscle ; (both which
aponeuroses over the internal half of the muscle
are so adherent to each other as to form but
one lamina;) and in its inferior fourth by the
conjoined aponeuroses of the two obliqui and
transversalis.

_ The posterior wall of the sheath is deficient

superiorly where the muscle covers the carti-

lages of the ribs with which it is in contact,
and inferiorly for a space corresponding to the
inferior fourth of the muscle. So much of it as
exists is formed by the tendon of the transver-
‘salis and the posterior lamina of that of the
internal oblique, so that the rectus appears to

have passed at its inferior extremity through a

transverse slit in these conjoined tendons, so as

to get between them and the peritoneum.
rectus muscle covers, at its superior ex-

tremity, the cartilages of the two last true ribs

anda part of those of the two first false, and

,

also the xiphoid appendix. The internal mam-
4 and epigastric arteries are found behind it
in the sheath.

Between the recti muscles is the fibrous cord
called linea alba, produced by the interlace-

_ * Also called enervations.— Winslow. They are,
says Meckel, incontestably incomplete repetitions of

{ the ribs in the walls of the abdomen.

__ t Hence Meckel classes it among the polygastric
muscles,

ment of the aponeuroses of the opposite sides,
noted in surgery as being in its inferior half the
seat of the operations of paracentesis abdominis,
paracentesis vesice supra pubem, the supra-
pubic lithotomy, and the Cesarean operation.
This cord extends from the xiphoid cartilage to
the symphysis pubis, with the anterior liga-
ment of which articulation it is identified. - It
does not present the same breadth in its whole
course, being broader in the umbilical region
than elsewhere. In this region we find in the
linea alba the perforation which gave passage to
the umbilical vessels in the foetus and the
urachus, and through which the fibrous remains
of those vessels pass to be inserted into the
skin, whereby is formed the cutaneous depres-

‘sion which marks the situation of this opening.

In the adult the umbilicus may be considered
as a point of considerable strength ; in the esti-
mation of some it is the strongest point in the
abdominal parietes : in dissecting away the skin
at this point, we find subjacent to it a very con-
densed cellular tissue, to which and to the
skin the fibrous cords into which the umbilical
vessels have degenerated adhere closely ; these
cords, too, adhere not only to the skin, but
likewise to the margin of the fibrous ring
through which they pass. “ The umbilical
opening, therefore,” says Scarpa, “‘ in the
infant two months after birth, and still
more in the adult, is not only like the other
natural openings of the abdomen, strength-
ened internally by the application of the peri-
toneum and of the cellular substance, and on
the outside by the common integuments, but it
is likewise plugged up in the centre by the
three umbilical ligaments and by the urachus ;
these ligaments form a triangle, the apex of
which is fixed in the cicatrix of the integuments
of the umbilicus, the base in the liver, in the
two ilio-lumbar regions, and in the fundus of
the urinary bladder; by this triangle is formed
a strong and elastic bridle, capable of itself
alone of opposing a powerful resistance to the
viscera attempting to open a passage through
the aponeurotic ring of the umbilicus, which
apparatus does not exist at the inguinal ring or
femoral arch.” * .
_ In the foetus the ring of the umbilicus is
pepicienally larger than at any period after
irth when the cicatrix is fully formed: it is,
however, at the full term, or even at the seventh
or eighth month, and in the healthy state of the
parts, equally filled up by the umbilical vessels
and urachus, and we would say is equally
capable of resisting intestinal protusion as at
any subsequent period. Hence it may be in-
ferred that congenital umbilical ruptures are
always of very early date, being attributable to
the persistence of the opening at the umbilicus,
and the continuance in it of the intestinal pro-
longation which exists there naturally at a very
early period. It may likewise be inferred that
the rupture in the adult can much more easily
occur in the vicinity of, than through the umbi-
lical ring; and experience confirms this deduc-
tion from the anatomy of the parts.

* Scarpa on Hernia, p. 373. |

10 ABDOMEN.

Above the umbilicus the linea alba is from
two to four lines broad in the greater part of its
extent; and below the umbilicus it gradually
tapers down to the pubis, at the same time in-
creasing in thickness.*

5. Pyramidalis (pubio-sub-umbilical). At
the inferior extremity of the recti, and separa-
ting their origin, are two small muscles of a
pyramidal form; their bases are inferior, and
attached to the symphysis and body of the
pubis, and uniting ligaments, and their apices
superior and inserted into the linea alba by
small tendons, from two to three inches above
the symphysis pubis. Each muscle is enve-
loped in a distinct sheath, and lies a little more
prominently than the origin of the rectus of the
same side. These muscles are not unfrequently
absent. Sometimes, on the contrary, there have
been two on one side and one on the other, or
even two on each side.+

The muscles which enter into the composi-
tion of the posterior wall of the abdomen are
chiefly those which occupy the lumbar region
of the back, filling up that empty space which
in the skeleton is observed on each side of the
spinal column between the crista ilii and the
last rib. In dissecting from behind forwards
in this region, having removed the skin and lax
cellular tissue already described, we come upon
the strong fibrous expansion, the fascia lumbo-
rum. ‘This has extensive osseous attachments,
and thus firmly binds down the subjacent mus-
cles. When it isremoved, the lumbar portions
of the sacrolumbalis and longissimus dorsi, and
a little of the spinalis dorsi, are brought into
view, the two former of which are described by
some as a single muscle—the sacrospinalis.
The external of these muscles is the sacrolum-
balis, and its outer margin may be said to con-
stitute the limit of the posterior wall of the
abdomen in that direction. In this situation
the posterior and middle layers of the tendon
of the transversalis separate from each other to
ensheath these muscles, the posterior layer
forming the fascia lumborum. We must refer
to thearticle Bacx for a particular description
of these muscles.

When the lumbar mass of muscles (as the
three preceding have been called) has been re-
moved, the next part brought into view is the
anterior layer of their fibrous sheath formed by
the middle lamina of the transversalis tendon,
which is inserted into the apices of the trans-
verse processes. This lamina is thin and semi-
transparent, so that the fibres of the muscle

* <« The linea alba performs the same office in
the abdomen as the sternum does in the thorax, with
this only difference, that it is not formed of bone.
The anterior tendons of the broad muscles are at-
tached to it, in the same way that the cartilages of
the ribs are articulated with the sternum, and the
difference of tissue which exists between it and the
sternum is attributable to the general difference of
structure between the abdominal and pectoral cavi-
ties, the latter being formed almost entirely of
osseous parts, whilst the walls of the former are
fleshy and tendinous.”— Meckel.

+ Meckel says that this muscle rarely presents
anomalies ; in this he must be mistaken, as its ab-
sence is certainly not a rare occurrence.

which lies immediately before it, are seen
through it. This muscle is the

Quadratus lumborum (ilio-costal, ilio-lumbi- |

costal). The term quadratus is applied to this
muscle, more from its quadrilateral form than
from any nearer resemblance to a square, in-
asmuch as all its sides are unequal. ‘The most
fixed attachment of this muscle is its inferior,

where it is inserted by tendinous fibres into the

iliolumbar ligament and into the inner lip of the
crista ilii for about an inch to the outer side of
the insertion of that ligament. From these points
the fibres proceed vertically upwards, the ex-
ternal ones going to be inserted into the inferior
margin of the last rib for nearly its entire
length, and the internal fibres, those in parti-
cular which are attached to the ligament, ter-
minating by four aponeurotic tongue-like bun-
dles, which are inserted into the anterior surface
of the transverse processes of the four superior
lumbar vertebre near their bases. The several
bundles which end in these tongue-like pro-
cesses vary in length; those which are external
being the longest, as going to higher vertebre.
This muscle is covered on its anterior or abdo-
minal surface by the anterior lamina of the
tendon of the transversalis muscle, by which it
is separated from the diaphragm as well as
from the psoas magnus.* The last dorsal
nerve and the first two branches of the lumbar
plexus, pass between the quadratus and the
aponeurotic lamina which covers it.

Psoas magnus, (ou, lumbus) (prelombo,
trochanterien, lumbaris.) 'The greatest por-
tion of this muscle belongs to the abdominal
region ; it lies along the side of, not only the
lumbar but also of a small portion of the dorsal
region of the spine, lodged in the angle between
the transverse processes and bodies. It passes
as high up as the twelfth dorsal vertebra, to the
body of which as well as to those of the four suc-
ceeding lumbar vertebre, and to their interven-
ing fibro-cartilages, the muscle is attached: it
likewise is attached to the bases of the corres-
ponding transverse processes, so that the inter-
vals between the portions that are attached to
the bodies, and those to the transverse processes,
correspond to the intervertebral foramina or
points of exit of the lumbar nerves, the an-
terior branches of which plunge at once into
the substance of the psoas muscle to form the
lumbar plexus. The several bundles which
thus take their origin from the vertebra form
a thick rounded muscle, which passes nearly
vertically downwards, inclining a little out-
wards, over the brim of the true pelvis, so as
often to appear to encroach upon the circum-
ference of the upper outlet of that cavity. A
little way above Poupart’s. ligament the mus-
cular fibres are inserted around a strong thick
tendon. This tendon, which had commenced
high up by distinct portions in the interior of
the muscle, passes under Poupart’s ligament
over the horizontal ramus of the pubis. It
descends over the capsular ligament of the hip-

* See fig. 4, f; see also fig. 5, where on one side
the muscle has been removed from between the
lamine of the transversalis tendon.

ee ee ee

ABDOMEN.

joint (from which as well as from the ramus
of the pubis it is 2 moras by a bursa) over
the head and along the inner side of the neck
of the femur, and is inserted into the posterior
part of the trochanter minor at its base, being
separated by a small bursa from the surface of
that process. As the tendon is passing over
the ramus of the pubis, it receives by its outer
margin a series of fibres from the iliacus in-
ternus muscle. At its superior portion the
psoas muscle is covered by a thin fibrous ex-
pansion, which is attached on the one hand to
the apices of the transverse processes, and on
the other to the bodies of the upper lumbar
vertebre ; this expansion, the arcus interior of
Senac and Haller,* also called ligamentum
arcuatum, separates the psoas from the dia-
phragm. Below this the psoas muscle is
covered with a lax, and in some degree fatty
cellular tissue, which separates the muscle from
the kidney externally, and from the peritoneum
and ureter within, excepting where the psoas
parvus covers it, and on the right side where the
vena cava lies upon it. Along its internal margin
are the lumbar portion of the sympathetic, the
- crura of the diaphragm, more especially on the
left side, and on this side too the aorta ap-
proaches a little its internal margin. The
common and external iliac arteries and veins
lie along the internal margin of the pelvic
hag of the muscle, which is covered by the
ascia iliaca. The several branches of the
lumbar plexus issue from this muscle at its
external margin, and the genito-crural nerve
descends in front of it inferiorly. We refer
to the article on the muscles of the thigh for a
further account of this muscle, its. relations in
the upper part of the thigh, and its actions.

Psoas parvus, (prelombo-pubien). This
muscle is similar to the psoas magnus in
course and position. It is very much elongated,
its fleshy portion being small and tapering. Su-
sent it is attached to the body of the first
umbar vertebra, and to the intervertebral sub-
stance between it and the last dorsal, and
sometimes to the body of the last dorsal ver-
tebra. The fleshy belly soon ends in a flattened
tendon, which descends obliquely downwards
and outwards over the anterior surface of the
psoas magnus, and at its inferior extremity ex-
ora considerably, and is inserted along the
inea ilio-pectinea near the junction of the
ilium and pubis. An expansion from the
‘margins of this tendon becomes united on the
outside to the fascia iliaca, and on the inside
to the internal portion of the same fascia which
covers the great psoas, and passes beneath the
iliac vessels to become united at the brim of
the 9 i to the pelvic fascia.

e must not omit to state that the crura of
the diaphragm, as they descend over the bodies
ofthe lumbar vertebre, (see DiapHRAGM,) may
be regarded as entering into the formation of
the posterior wall of the abdomen. The inferior
wall of the abdomen is not devoid of muscle,
although those muscles can exercise very little, if

* Vid. Haller Icon. Septi Transversi. Op. Minora,
tom. 1.

11

any influence upon the contents of the cavity.
The iliac fossa affords a large surface for the
attachment of one of the principal muscles
connecting the thigh with the trunk. This
muscle is named

Lliacus internus, (iliaco-trochanterien.) This
muscle fills up the iliac fossa, to the whole of
whose concavity as well as to its margin, and
the two anterior spinous processes of the ilium
and the interval between them, its fibres are
attached. From these several points of origin
the fibres converge to form a thick and
broad belly, which passes over the upper part
of the acetabulum and horizontal ramus of the
pubis, filling up the external portion of the
space between that boneand Poupart’s ligament ;
and it is inserted, as we have already observed,
into the outer margin of the tendon of the
psoas magnus, which is for that reason gene-
rally described as the common tendon of the
psoas and iliacus. The anterior surface of this
muscle is traversed by two of the external
branches of the lumbar plexus (inguino-cuta-
neous), and the anterior crural nerve passes
between its internal margin and the psoas
magnus.

The superior wall of the abdomen is entirely
formed by the muscular vault of the diaphragm,
which by its contraction and relaxation exer-
cises a considerable influence on the abdominal
contents,and causes very obvious changes in the
form of the cavity. The concavity of this vault
is towards the abdomen, and is greater on the
right side than on the left, in consequence, as
it is said, of the presence of the liver on that
side. It is through the several openings in this
wall that a communication is established be-
tween the thorax and abdomen. The largest of
these openings are, that on the right side,
which is completely tendinous, for the passage
of the vena cava; the opening for the cso-
phagus; and that for the aorta; in addition
to these there is a small one behind the
centre of the xiphoid appendix formed by a
divarication of the anterior fibres of the dia-
phragm, through which the cellular tissue of
the anterior mediastinum communicates with
the abdominal subserous tissue. There are,
moreover, openings for the transmission of the
splanchnic nerves, and the continued trunks of
the sympathetics, as well as of branches of the
an arteries and nerves, and the abdominal

ranches of the internal mammary. The par-
ticular description of this muscle will be given
under the article DiapHracM.

4. The next element which enters into the
formation of the abdominal parietes is a fibro-
cellular expansion, which, varying in density
in different situations, lines the whole internal
surface of the muscular walls. It is strongest
and exhibits most of the real fibrous character
in the iliac region on the anterior wall, and
over the iliac fossa in the inferior. In the
former situation it has received the name of
Sascia transversalis, which was applied to it by
Sir A. Cooper in consequence of its close con-
nexion with the transversalis muscle: in the
latter, it is called the fascia iliaca, from its
connexion with the iliac fossa and muscle.

12

The fascia transversalis is best seen by re-
moving the muscles which lie anterior to it: it
is then distinctly observed to extend from the
outer margin of the rectus muscle internally
over the posterior surface of the anterior wall of
the abdomen, and gradually to assume the
character of a thin but condensed cellular la-
mella over the abdominal surface of the lateral
wall: it may, however, be traced internally as
far as the linea alba behind the rectus muscle,
but here it is extremely thin, and has totally
lost the fibrous character. Inferiorly this fascia
adheres to Gimbernat’s ligament and to the
reflected margin of Poupart’s, from which it is
said, by some French anatomists, to originate.
Along the line of Poupart’s ligament and ex-
ternal to it along the crista ilii, this fascia is
united with the fascia iliaca, the union be-
ing indicated by a white opaque line formed
by a thickening of the membrane, taking the
course of Poupart’s ligament and the crista ilii,
except where it is interrupted for the passage of
vessels or other parts. Superiorly, the fascia
transversalis also degenerates into a cellular
lamella, which passes on the transversalis
muscle to the diaphragm. It is for a short
distance above Poupart’s ligament that this
fascia demands most attention; here it forms the
posterior wall of the inguinal canal, and ata
point a little external and superior to the middle
of Poupart’s ligament it presents an opening or
separation of its fibres, through which the sper-
matic vessels and vas deferens united by lax
cellular tissue pass into the inguinal canal,
carrying around them a funnel-shaped mem-
brane which seems to be a prolongation from
or continuation of the margins of this opening,
but which is in texture merely a condensed cel-
lular layer. This prolonged membrane is the
first covering which the spermatic cord receives
upon its formation, which takes place as its
several constituent parts meet at the opening or
slit in the fascia transversalis ; it immediately
invests the cellular tissue connecting these parts,
which is the tunica vaginalis of the cord; as
it proceeds, the cremaster muscle adheres to it
from the external oblique and _transversalis
muscles, and this again receives at its exit
through the external abdominal ring another
cellular expansion, to which we have already
alluded.

The opening or slit in the fascia transversalis
which we have just described is denominated
by anatomists the internal abdominal ring,
although, if we speak with reference to the mid-
dle line, it is external to the opening in the
tendon of the obliquus externus, which is called
the external ring. It would certainly be more
consistent with the ordinary use of these ad-
jectives in anatomy to reverse their application,
or if the term anterior were applied to the ex-
ternal ring, and posterior to the internal, every
purpose would be answered.

The direction of the internal abdominal ring
is vertical and inclined very slightly outwards.
When the fibrous character of the fascia trans-
versalis is obvious, we can generally observe
two very distinct portions of it, one on each
side of the ring. The fibres of the external

ABDOMEN.

portion pass upwards and inwards; those of
the internal portion, which are generally stronger
and more developed than in the external, pass
upwards and outwards so as to decussate with
the external fibres at the upper extremity of the
ring. The outer margin of this internal portion
often presents towards the ring a lunated ap-
pearance, over which the vas deferens turns ata
sharp angle; it can be best seen by examining
the parts from behind after the peritoneum has
been removed.* The fascia transversalis is
continued upwards along the posterior and
lateral surface of the abdominal muscles and
over the diaphragm under the form of a fine
lamina of very condensed cellular membrane,
which adheres pretty closely to the muscles,
but especially to the diaphragm, where it
seems to be incorporated with the proper cel-
lular covering of that muscle. We refer to
the article Groin, ReGion oF THe, for further
particulars respecting the fascia transversalis.
In the iliac fossa we find a very distinct
fibrous expansion covering the whole abdo-
minal surface of the iliacus internus muscle.
This is the fascia iliaca. It is seen by raising
the peritoneum and the subperitoneal cellular
tissue from the fossa. Inferiorly this fascia is
connected with the fascia transversalis along
the line of Poupart’s ligament, except where
that connexion is interrupted by the passage of ©
the vessels under the ligament. That space
comprises the interval between the inner margin
of the tendon of the Psoas and Gimbernat’s
ligament; and here the fascia lies close to the
horizontal ramus of the pubis, and passes be-
hind the vessels into the upper part of the thigh,
where it adheres to the linea ilio-pectinea,
and seems to become continuous with the
fascia lata. Externally the fascia iliaca is con-
tinuous with the fascia transversalis along the
crista ilii, where an opaque line indicates the
union, and just internal to which it splits to
ensheath the circumflexa ilii artery. On the
inner side of the iliac fossa this fascia unites
with the pelvic fascia along the brim of the
pelvis, this union being likewise indicated by
an opaque line similar to that already noticed
along the crista ilii. To arrive atthis point the
fascia, in proceeding from without inwards,
passes over the iliacus internus, then over the
psoas magnus and parvus, upon which it is
thinner than elsewhere ; it then passes behind
the iliac artery and vein, and arrives at the
pelvic margin. Posteriorly this fascia is con-

tinuous with a thin and less fibrous expansion

which covers the psoas and quadratus lumborum
muscles, adheres to the ligamentum arcuatum,
and is identified superiorly with the cellular
expansion on the diaphragm, and externally
with the fascia transversalis.

It has already been stated that the iliac fascia
asses behind the iliac vessels. These vessels
ave also anterior to them a fibrous or cellulo-

fibrous expansion, which is connected on the
inner and outer side to the fascia iliaca. Some

* This lunated margin is very well delineated by
Cloquet in the third figure of the first plate annexed
to his work on Hernia, now translated by Mr. A. M.
M‘Whinnie.

ad ABDOMEN.

consider this as merely a portion of the subperi-
toneal cellular tissue, but I cannot help regard-
‘ ing it as a process from the iliac fascia itself to
‘ envelope the vessels just as that fascia envelopes
the circumflexa ilii artery between two lamina
at its outer margin. I have never seen an in-
stance in which this sheath was not perfectly dis-
tinct, in some cases it is of considerable strength,
but in the majority weak and transparent. It
was this sheath which impeded Mr. Abernethy
in one of his earliest operations for applying a
ligature to the external iliac artery.*
The connexion which the iliac fascia has
- with the fascia transversalis at the crural arch,
and the relation both bear to the iliac vessels at
their exit to become femoral, suggested to Mr.
Colles a comparison which is constantly referred
to by anatomists. “It may be said to resem-
ble,” he says, “a funnel, the wide part or
mouth of which occupies the hollow of the
__ ilium and lower part of the abdominal muscles,
and the narrow part or pipe of which passes
downwards on the thigh. The mouth of this
funnel may be supposed to rise as high as the
upper edge of the iliac muscle, and to be turned
toward the cavity of the abdomen: the pipe
joins the wide part where the external iliac
vessels are passing under Poupart’s ligament,
and it is continued down on the thigh, so low
as to reach the insertion of the saphena into the
femoral vein.”’+
From the preceding sections it appears that
a fibro-cellular expansion lines the whole in-
ternal surface of the abdominal parietes. It is
so likewise with the pelvis, and also with the
_ thorax. The cavity of the cranium, too, is
lined with a fibrous membrane, although of a
different nature, and doubtless performing a dif-
ferent office.
5. Between the internal fibrous expan-
sion of the abdomen and the peritoneum is
acellular tissue, which presents different cha-
_ facters in each region; it is the subperitoneal
cellular tissue. Along the anterior wall it is
_ thin and fine, except inferiorly opposite the in-
| ternal abdominal ring, where it becomes more
abundant, as well as in the hypogastric region,
_ immediately above the pubis. In the iliac
_ fossa and lumbar region it is lax and abundant,
especially in the latter, where there is also a
_ considerable quantity of fat surrounding the
kidney. In the iliac fossa this cellular tissue
is stretched across the crural ring, and forms
what Cloquet describes under the name of
a erurale. On the superior wall it is ex-
_ tremely fine, and in very small quantity. Im-
mediately behind the sternum, and in the mid-
_ dle line, this cellular tissue communicates with
_ that of the mediastinum through a separation
f the anterior fibres of the diaphragm.
___ This subserous cellular tissue forms the pri-
| of all herniz, which push a
sac before them, and as being the
’ ia constituting the nearest investment of the
‘Sac, it is generally called the fascia propria.

_ ™ Abernethy’s Surgical Works, vol. i. p. 225.
___ ¢ Colles’ Surgical Anatomy, pp. 68,

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Opposite the crural canal this cellular tissue is
often so abundant, as, when condensed by the
pressure of the hernial tumour, to form an ex-
ansion over the sac of considerable thickness.
ometimes it contains fat, and not unfrequently
we find a large lymphatic ganglion in it, filling
up the crural ring.

6. Peritoneum.—A considerable part of the
abdominal surface of the walls of the abdomen
is lined by a very fine transparent serous mem-
brane—the peritoneum, which is likewise con-
nected, to a greater or less extent, with every
viscus within the cavity. In consequence of
this double connexion, it happens that in various
situations the peritoneum is reflected from the
wall of the abdomen upon an adjacent viscus,
and thus are produced various folds of this mem-
brane, which demand the attention of the ana-
tomist. These folds are rendered distinct when
such a section of the anterior abdominal wall is
made as without dividing them to allow of it
being held apart from the viscera. I shall
enumerate these folds in describing the relation
of the peritoneum to the several walls. The
anterior wall of the abdomen is entirely lined
by peritoneum, and has in connexion with it
four folds, all of which, as it were, radiate from
the umbilicus. In the adult these folds are
reflected round four ligamentous cords (three
of which are the remains of bloodvessels in
the foetus), which meet at the umbilicus and
diverge, one upwards, backwards, and to the
right side (the obliterated umbilical vein),
two downwards and outwards towards Pou-
part’s ligament on each side, so as to pass
behind the inguinal canal, nearly midway
between the two rings (the obliterated um-
bilical arteries), and the fourth nearly ver-
tically downwards along the middle line to be
inserted into the apex of the bladder (the ura-
chus). The four folds are similar in direction
to that of the fibrous cords contained within
them: the fold which passes upwards towards
the liver is falciform, the concavity being di-
rected downwards and backwards. From its
connexion with the convex surface of the liver
it is also called the falciform ligament of the
liver, and the fibrous cord contained in its in-
ferior margin, the ligamentum teres. The in-
ferior and external folds pass each from
the umbilicus, downwards and outwards to
the iliac fossa, to a point a little on the inner
side of the internal abdominal ring, where it dis-
appears, being continued externally over the
iliac fossa, and internally behind the rectus
muscle. This fold, when stretched towards
the umbilicus, evidently forms the partition
between two pouches, the external and in-
ternal inguinal pouches, which correspond re-
spectively to the internal and external abdo-
minal rings, and indicate the situations at
which make their escape those two forms
of inguinal hernia, which, from their connexion
with these pouches, are called by Hesselbach
external and internal inguinal hernie ; the for-
mer being that by oblique descent, the latter
that by direct descent.

The fourth or vertical fold indicates the —

14

reflection of the peritoneum from the anterior
abdominal wall upon the superior fundus and
posterior surface of the bladder: when that
viscus is empty and contracted, this fold dis-
Hoth totally ; it is more apparent when the
bladder is partially filled, and is still more
distinct in the foetus in consequence of the
greater size of the urachus at that period.
Just above the pubis the peritoneum is con-
nected to the abdominal wall by a very lax
cellular tissue; and accordingly when the blad-
der is much distended, the peritoneum is
pushed upwards, and stripped off the abdo-
minal wall to an extent proportioned to the
degree of distension of the bladder, so that its
anterior surface is then in immediate contact
with the abdominal wall, and may be opened
with impunity so far as the peritoneum is con-
cerned.

The lateral walls of the abdomen are like-
wise completely lined by peritoneum, which
extends backwards as far as the junction of
these walls with the posterior, where it is re-
flected from them so as to involve the ascending
colon on the right side and the descending on
the left, and here it forms on each side the
folds respectively termed right and left meso-
colon. From the right lateral wall the peri-
toneum is continued upwards upon the dia-
phragm, and contributes to form the right
ateral ligament of the liver; on the left side
it is continued in a similar manner on the
diaphragm, and in passing from the spleen to
that muscle forms the fold called splenico-
phrenic.

The concave surface of the diaphragm is in
greatest part lined by peritoneum: the an-
terior half of the muscle is uninterruptedly
covered by peritoneum, which adheres very
closely to the central tendon, but is much more
easily separated from the muscular portion.
On the right side and in the middle, in front of
the esophageal opening, the peritoneum ‘is re-
flected from the diaphragm to the liver, forming
the right lateral, coronary, and left lateral liga-
ments of that organ. The posterior half of
this surface is likewise covered by peritoneum,
that membrane being deficient for a little way
behind the opening for the vena cava and
behind and on each side of the cesophageal
and aortic openings: the crura of the diaphragm
are covered chiefly on the outer side.

The peritoneum comes into immediate con-
tact with the posterior abdominal wall only in
a very small portion of its extent: in tracing it
on the right side we find it covering the right
colon, then passing inwards over the kidney
and suprarenal capsule, the duodenum and vena
cava, to the crus of the diaphragm above, and
in the middle and below, where it also covers
the vena cava, and the renal vessels, to form
the right or superior lamina of the mesentery.
On the left side it covers in a similar manner
the left colon, the left kidney and capsule, and
that portion of small intestine which projects
just to the left of the superior mesenteric artery,
which may be regarded as the commencement
of the jejunum; below this it manifests its

ABDOMEN.

continuity with the layer of the opposite side
by forming the left or inferior lamina of the
mesentery. This lamina commences at the
left side of the body of the second lumbar
vertebra; as it descends, it gradually crosses
more in front of the aorta, so as to terminate
at the right sacro-iliae symphysis; the right
lamina is situated quite on the right side of the
spine.

dn the iliac fosse the peritoneum is in con-
nexion with the fascia iliaca, except where it is
separated by the cecum on the right side
(on which side it sometimes forms a fold termed
mesocecum,) and by the sigmoid flexure on
the left. Internal to these portions of intestine
on each side, the peritoneum covers the ex-
ternal iliac artery and vein, from which it is
separated by a very loose and sometimes adi-
pose cellular tissue, and by a process of the
iliac fascia, to which allusion has already been
made.

From the preceding description of the con-
nection of the peritoneum with the parietes
of the abdomen, it will appear how few are
the situations at which the surgeon could cut:
through any portion of these walls without
risk of wounding the serous membrane. Im-
mediately above the pubis this may be done
in consequence of the abundance of cellular
membrane there which separates the serous
membrane from the wall; but in the con-
tracted state of the bladder the operator must
proceed with the greatest caution: in the dis-
tended state of that viscus, however, the wall
of the abdomen is deprived of its lining to an
extent proportionate to the height to which the
bladder ascends behind the recti muscles; and
accordingly it is under such circumstances
that the paracentesis vesice supra pubem, and
the high operation for the stone may be per-
formed with impunity to the serous membrane.
At the posterior wall an instrument may be
passed into any part of the posterior surface
of the kidney without injury to the peritoneum ;
the pelvis of the kidney, or any part of the
abdominal course of the ureter, may be opened
too, or the vena cava; and by cutting into the
bodies of the vertebre, and the muscular por-
tion of the posterior wall in the dead body,
a view of all the parts which lie upon that wall
may be obtained without at all injuring the
peritoneum.*

Further details respecting the anatomy of
the peritoneum will be found in the article
under that head.

Vessels and nerves of the abdominal walls.—
a. The arteries —The most important arterial
ramifications are found in the anterior wall.
In the superficial fascia we find the superficial
epigastric artery or tegumentary artery, which
exists as a trunk in the iliac regions. i

artery, arising from the femoral, pierces the 4

fascia lata, and passes over Poupart’s ligament

upwards and inwards, crossing the anterior —

* The reader may examine with advantage, Lud-

wig, Icones cavitatum thoracis et abdominis a tergo 4

apertarum. Leipzig, 1789,

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:
4
4
id

wall of the inguinal canal between the two
rings ; it is distributed in the integuments and
fascia of the iliac and umbilical regions, and anas-
tomoses with its fellow of the opposite side, and
by deep branches which pierce the aponeuroses,
with the deep epigastric artery. In the epigas-
trium and hypochondria the superficial fascia
and integument are supplied by cutaneous
branches from the internal mammary and the
inferior intercostals. The deep-seated parts of
this region are likewise supplied from the last-
named arteries ; the largest and most constant of
which is the abdominal branch of the internal
mammary, which in the sheath of the rectus
supplies that muscle, and establishes an im-
portant communication with the epigastric:
this anastomosis is said to have been known to
Galen, who by it proposed to account for the
sympathy which exists between the uterus and
the breasts.* Another branch of the mammary
supplies the muscles external to the rectus; it
runs between the obliquus internus and trans-
versalis, and is lost in anastomosing with the
inferior intercostal, the lumbar, and the circum-
flexa ilii arteries.

Inferiorly, the abdominal wall is supplied
by two considerable and very constant arteries,
viz. the epigastric, which may be distinguished
from the artery that supplies the integuments
by the appellation deep, and the circumflexa ilii.
The epigastric artery arises in general from the
external iliac a little way above Poupart’s liga-
ment; it at first inclines downwards to that
ligament, and then turns upwards, and directs
itself forwards and inwards, crossing the iliac
vein; it then runs along the posterior surface of
the anterior wall of the abdomen, inclosed be-
tween the peritoneum and fascia transversalis,
at first situated between the external and inter-
nal abdominal rings, and on arriving at the
rectus muscle, the sheath of which it enters
about two inches above the pubis, it gives off
branches from either side to the abdominal
muscles and peritoneum, and behind the linea
alba, establishes a very free inosculation with
__ its fellow of the opposite side. As it lies behind
_ the inguinal canal, the epigastric artery is much
nearer to the internal than to the external abdo-
minal ring, being to the pubic side of the
former ; here the vas deferens, as it passes up
_ from the pelvis to the inguinal canal, hooks
_ Over it, and receives one or two small branches
_ from it. In passing to the rectus muscle, this
artery lies internal to the linea semilunaris. It
_ enters the sheath of the rectus, and then termi-
nates by anastomosing with the internal mam-

, oa fe The course of this artery demands par-
et attention from the surgical anatomist in
_ reference to the operations for inguinal herniz,
and to that for paracentesis abdominis, when
_____ the abdomen is perforated in the linea semilu-
_ naris, The trunk of the artery is so distant

from the linea alba in its whole course, that it
is free from danger in any operation performed
in that line, or in the internal half of the rectus
muscle, and its security in such operations is
increased under the altered state of parts con-

a =~

AAA RA RRNA 26 BSB NA IN EB MAD GRR Ss Ca ap iA

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ABDOMEN.

15

sequent on pregnancy, ascites, or any abdomi-
nal tumour pressing similarly on the abdominal
wall. In these cases the distance of the artery
from the linea alba is increased by the flattening
of the rectus muscle, which results from its
compression. — (See Grorn, Recion oF;
Hernia; Itiac Artery.)

The circumflexa ilii artery comes likewise
from the external iliac, near to the origin of the
epigastric; it passes upwards and outwards to-
wards the spine of the ilium, runs along the
line of junction of the fascia iliaca with the
fascia transversalis, covered by the fascia, and
follows the circumference of the iliacus internus
muscle to end in anastomosing with the iliolum-
bar artery. From that part of the artery which
intervenes between its origin and the spine of
the ilium, come the principal branches which
it supplies to the abdominal muscles.

The lateral and posterior walls of the abdo-
men are supplied by the inferior intercostals, the
lumbar, the iliolumbar, the circumflexa ilii arte-
ries; the superior walls by the phrenic branches
of the internal mammary and by those of the
aorta. It is in cases where the aorta has been
obliterated that we can see best the extent of
arterial ramification on the abdomen, and can
appreciate the benefit of these numerous anas-
tomoses, and the connexion which they esta-
blish between the upper and lower portions of
the aorta.*

b. The veins.—The veins of the abdominal
parietes are much more numerous than the
arteries ; each artery has its accompanying vein
or veins, but those which are especially de-
serving of attention are the tegumentary veins
which accompany the superficial epigastric
artery, and those which ramify along with the
deep epigastric and mammary. The subcuta-
neous veins demand attention in consequence
of the considerable size which they sometimes
attain; this enlargement is commonly attendant
on ascites and on pregnancy, and is occasionally,
to a remarkable extent, a consequence of some
irregularity, obstructiont or retardation of the
circulation, in the deep-seated veins of the ab-
domen, more especially the inferior vena cava.
The veins which accompany the superiicial
epigastric artery empty themselves by one or
more trunks into the vena saphena at the upper
part of the thigh.

Two veins generally accompany the deep
epigastric artery, which empty themselves into
the externaliliac vein. These veins are equally
subject to enlargement with the preceding, and
from similar causes, and they are often found
in a varicose condition in women who have
borne many children.

Some curious anomalies have been observed
in the venous circulation of the anterior abdo-
minal wall, which, as being calculated to in-
terfere with the operator, the practitioner would

* See the interesting case of obliterated aorta re-
corded by Messrs. Crampton and Goodissen. Dub.
Hosp. Reports, vol. ii. :

+ Asin the case of obliteration of the inferior
vena cava from the pressure of an aneurismal
tumour observed by Reynaud. Journal Hebdom.
de Méd. vol. ii, p, 110.

16 ABDOMEN.

do well to note. M. Meniere* has described
a case in which a very large vein, arising from
the external iliac, passed up along the linea
alba to the umbilicus, was continued along
the obliterated umbilical vein, and opened into
the vena porte. In another case, recorded by
Manec, the vein originated in the same manner
by two roots, reached the umbilicus, taking
a course parallel to the umbilical artery, formed
an arch outside the navel, and having re-entered
the abdomen, opened into the vena porte. In
another instance which occurred to Cruveilhier
the superficial veins in the hypogastric region
were enormously enlarged, at the umbilicus
they ended in a trunk as large as a finger,
which communicated with the vena cava as it
passed under the liver.t Berard proposes to
explain, by the supposition of the existence
of such anomalies as those above described,
the occurrence of fatal hemorrhages from
wounds inflicted at the umbilicus, which have
been attributed to the persistence of the um-
bilical vein.t

c. The lymphatics.—Those on the anterior
wall communicate above with the axillary
glands, and below with those of the groin: the
deep-seated lymphatics of the posterior wall
communicate with the glands which lie along
the lateral and anterior surfaces of the lumbar
spine.

d. The nerves.—The nerves of the abdo-
minal parietes are derived from the inferior
intercostals and from branches of the lumbar
plexus. The seventh, eighth, ninth, tenth,
eleventh, and twelfth intercostal nerves termi-
nate in supplying the transverse and oblique
muscles and the recti; the twelfth lies in front
of the quadratus lumborum muscle, and gives
several filaments to that muscle. The ilio-
scrotal and inguino-cutaneous nerves are the
branches of the lumbar plexus which mainly
supply the inferior part of the oblique and
transverse muscles. One branch of the genito-
crural, which is found in the inguinal canal,
also sends some twigs to these muscles.

The posterior wall is supplied by the sub-
divisions of the posterior branches of the
lumbar nerves.

Physiological action of the abdominal parietes
and muscles.—We have already alluded to the
peculiarity which distinguishes the abdominal
cavity when compared with the other great
cavities, namely, that its walls are in greatest
part composed of contractile tissue. At first
view the muscular apparatus of the abdomen
would appear to be a great constrictor muscle
destined principally to exert its influence on
the cavity and its contents; but when we take
into account the attachments of those muscles

* Archives Gén. de Méd. t. x. p. 381. The
vascular distribution which existed in this subject
presents, as Meniere has remarked, a striking simi-
larity to that which is naturally found in the Saurian,
Ophidian, and Batrachian reptiles, viz. a division
of the general venous system which communicates
with the hepatic vena porte.

+ Velpeau, Anat. Chir. ed. 2. vol. ii. p. 32, and
Manec, Dissertation inaugurale. Paris, 1826.

t Dict. de Méd. art. Abdomen,

to the ribs, the vertebrae, and the pelvis, it
becomes evident that they must likewise be
destined to act upon the thoracic and pelvic
cavities, as well as upon the vertebral column.
In the constitution of the abdominal parietes
we observe, as Berard* remarks, the most
happy adaptation of structure to uses. A
completely osseous covering would have greatly
interfered with the functions of the abdominal
organs, which are liable to experience changes
both extensive and often very rapid, either by
reason of the introduction of alimentary matter,
whether solids or fluids, or by the disengage-
ment of gases within the digestive tube, or by
the progressive development of the impregnated
uterus. We may moreover add that an exact —
repetition of the structure of the walls of the
thorax would not have been well adapted to
the abdomen for the same reason, namely, the
too great resistance which it would afford to
compression from within, thereby interfering
with the distensibility of the enclosed viscera.
The resistance, too, which a wall so constituted
would afford to impulses from without could
not have been so easily adapted to the impetus
of the forces likely to act upon them as a
purely muscular wall whose contractions and
the intensity of them are obedient to the will.

The consideration of the action and uses of
the abdominal muscles naturally comes under
two heads :—1. their action upon the abdo-
minal cavity and its contents; 2. their influ-
ence on the trunk generally, or parts of it.

It is the muscles that enter into the compo-
sition of the ‘anterior and lateral walls of the
abdomen which act chiefly on the cavity’and
its contained viscera. The solidity of a con-
siderable portion of the posterior wall, and
the great strength of the lumbar muscles, give to
that wall such a power of resistance as enables
it to receive the compressed viscera without at
all yielding. A reference simply to the attach-
ments of the muscles of the anterior and lateral
walls is sufficient to shew that these muscles
when contracted must diminish the capacity
of the abdomen, both in the lateral and antero-
posterior directions; and as the posterior wall
is but little influenced, the viscera will be
pushed partly upwards against the diaphragm,
and partly downwards into the cavity of the
pelvis, where their further descent is opposed
by the levator ani. Hence it appears that
a degree of antagonism exists between the
diaphragm and the abdominal muscles, as
well as also between those muscles and the
levator ani. It is extremely difficult to maintain
the abdominal muscles and the diaphragm
at the same moment in a state of contrac-
tion; in general they alternately yield the
one to the other: and when it does happen
that they are simultaneously contracted, the
abdominal viscera must suffer an unusual de-
gree of compression; and it is not improbable

that vomiting is sometimes produced by such

a cause, and defecation, no doubt, is likewise
aided by it. The danger of the protrusion of ©
some of the hollow viscera between the fibres

* Loc, cit.

of the muscles is provided against by the
variation of direction in the fibres of the several
layers; thus the fibres of the obliqui are in
the directions of two intersecting diagonals,
and those of the transversalis are different from
- both. By this arrangement a sort of network
is formed, with meshes so small as to render
a protrusion perfectly impossible in the healthy
_ condition of the muscle. In the compression
of the viscera the abdominal muscles are most
completely congeneres, although the trans-
_ versalis seems to be the best adapted to this
action, and probably, for that reason, forms
the layer Ack is placed nearest the peri-
_toneum. The recti muscles are powerful
_ auxiliaries in affording a fixed point of attach-
‘ment in front for the aponeuroses of the broad
Muscles, and the pyramidales assist in a
similar manner by rendering tense the linea
alba. Is this constant action of the abdominal
parietes on the viscera necessary or favourable
the due performance of the functions of
organs, or to the continuance of the
abdominal circulation? There certainly does
not appear to be any evidence for the necessity
_of them for this purpose: that they are favour-
able to it may fe inferred from the fact that
_ they do bear their present relation to them. We
now from numerous experiments on animals,
that both the transmission of the intestinal
contents, and the abdominal circulation may
go on when the abdominal muscles have been
freely opened or removed. Hence we may
answer this question with perfect justice in
_ the words of Bichat: “The walls of the ab-
domen favour these functions by their motions;
but these motions are by no means essential
) them.”
__ It is in consequence of the power which the
abdominal muscles thus appear to amie: in
compressing the viscera, that some physiolo-
gists have attributed the act of vomiting to their
ction united with that of the diaphragm; and
Magendie, reviving the opinions of Bayle, Chi-
ac, and Shwartz,* went so far as to deny to
1e muscular coat of the stomach any partici-
tion in this act, and to ascribe it wholly to
1¢ influence of the abdominal muscles. But
clard, to whom the question was referred by
e Academy of Medicine of Paris, proved
tisfactorily that the abdominal muscles are
ve in producing vomiting when the sto-
is distended in a certain degree, and that
uscular coat of the stomach is also active
ptying the contents of that viscus. This
aller had arrived at long ago, and
it in the following passage :
ntissimum ergo videtur, vomitus qui-

to

oF"
LOOSE

bof

ee

dy

m causam esse in ventriculo eumque in con-
tionem niti propriis viribus atque aliquando
hitum perficere. Plerumque tamen irrita-
mem in ventriculo natam et sensum summe
kietatis, que vomitum precedunt, facere ut
levandam egrimoniam vires diaphragmatis
mous ee um abdominis excitate atque mo-

im de

homine amoliture, vomitum per-

ry

Haller,

/ Elementa Physiologie, t. vi.
xiv. .

ct. iv. §
* J OL, I,

ABDOMEN.

17

ficiant. Unde neque a sola voluntate in ple-
risque certe mortalibus vomitus cieri potest
neque a sola absque voluntate natura—Quare
recte conjunctas vires ventriculi et organorum
respirationis Cl. Viri fecerunt. Et videtur dia-
phragma etabdomen plus virium habere, quando
ventriculus aut cibis repletus est, aut clausis
ostiis distentus: tune enim magis ad perpen-
diculum proximum ventriculum comprimunt et
tota contingunt.”*

If it be admitted that the abdominal muscles
are active in producing vomiting, and in defe-
cation and micturition, it will follow likewise
that they must assist in parturition. While
these pages were preparing for press, the fol-
lowing passage presented itself to me, in an
able and interesting review of M. Velpeau’s
Treatise on Midwifery. It so fully illustrates
the part which the abdominal muscles take in
promoting parturition, that I venture to tran-
scribe it, “ It is certain,” says the reviewer,
“that a woman who ‘bears down’ as it is
termed, with all her force, who makes the most
of her pains, however feeble they may be, will
thus accelerate her delivery; and that another
may more or less delay delivery by voluntarily
opposing muscular action as much as she can.

or example ;—a woman was admitted for de-
livery at M. Baudelocque’s theatre; labour
went on regularly, and the pupils assembled.
The dilatation of the cervix now slackened, and
no progress was made during the whole night.
The éléves were fatigued and retired ; the pains
immediately returned, and dilatation again
went on. The young men again entered; the
phenomena of labour again ceased. Baude-
locque, suspecting the cause, gave a hint to the
students to retire, but to be at hand and enter
upon a given signal. The patient now began
to ‘ bear down,’ and the head of the child was
quickly at the vulva. The spectators were
once more brought to the scene of action, and
the labour was speedily terminated ; for it had
now advanced too far to be suspended by any
voluntary effort or moral alarm of the woman.’’+

The fixedness of the inferior attachment of
the abdominal muscles to the pelvis, and the
mobility of the ribs, to which they are attached
superiorly, evidently indicate that these muscles
are destined to act upon the thoracic cavity.
The transversalis does not, from the direction of
its fibres, admit of this action to any extent;
that office, therefore, devolves chiefly on the
obliqui and recti. When these last-named
muscles act together, they must compress the
inferior opening of the thorax, draw its inferior
margin downwards and backwards, and, by the
compression thus exerted on the abdominal vis-
cera, push them upwards against the diaphragm,
which muscle is thus made to ascend into the
thorax, and that cavity is thereby diminished
in its vertical and antero-posterior diameters,
and also, though not so obviously, in its trans-
verse. Hence the lungs become so compressed
as to be adapted to the altered capacity of the

* Haller, ubi supra. See, also, Richerand, Physi-
ologie par Berard, art. Digestion, § xxiv.
t Medical Quarterly Review for April, 1835. p.100.
c

18

thorax, and thus these muscles must be con-
sidered as very important agents in the act of
expiration. It must be observed, however,
that in order that they may act on the chest
with their full force, it is necessary that that
cavity should have been previously in a state
of full dilatation, for under such circumstances
the fibres of the obliqui and recti are con-
siderably stretched and their levers elongated.*
It is in the excited states of expiration, cough-
ing, sneezing, &c., that this action of these
muscles is most obvious.
But it is in the motions of the trunk that
the abdominal muscles are called most into
play. In all the inflexions of the trunk, whe-
ther the body be horizontal or erect, these
muscles are main agents. When the body is
recumbent on a horizontal plane, the recti are
thrown into action when the individual attempts
to raise up the thorax, the spine being thereby
brought into the state of flexion. Ifthe thorax be
fixed, while the body is still supine, the action
of the recti will draw the pelvis upwards and
forwards, causing slight flexion of the spine,
and. slightly approximating the upper margin
of the pelvis to the lower margin of the thorax.
Although the recfi muscles are the principal
agents in thus flexing the spine, the obliqui co-
operate with them very powerfully, and are
especially useful in maintaining the due propor-
tion between the middle and lateral regions of
the abdomen. When the two obliqui of the
same side act together, the direction of their
force is, as with all oblique muscles whose
fibres decussate, in the diagonal between their
fibres; and, therefore, when the obliqui of op-
posite sides act in unison, they very powerfully
aid the recti in flexion of the spine, approx-
imating the thorax and pelvis anteriorly. When
the obliqui of one side act, they produce a
lateral inflexion of the trunk to that side,—the
middle and opposite region of the abdomen
being in this position rendered prominent by
the viscera pushed over from the side of the
contracted muscles. In what have been called
the rotatory motions of the trunk, the obliqui
muscles of the same side antagonize each other ;
thus in that movement by which the anterior
surface of the trunk is made to look to the left
side, the obliquus externus of the right side will
co-operate with the obliquus internus of the
left, but the obliquus internus of the right will
antagonize the external muscle of the same
side. ‘“ These muscles,” ( obliqui externi et in-
terni,) says Dr. Barclay, “ from occupying
the whole of the lateral aspects extending be-
tween the ilia and ribs, and from acting at the
greatest lateral distance from the centre of
motion, must always be muscles principally
concerned in producing inflexions dextrad and
sinistrad on the lumbar vertebrz, principal di-
rectors in all the inflexions sternad and dorsad;
and, from the assistance which they give to the
recti, principal librators also of the trunk, whe-
ther we be sitting, standing, or walking.”
The reciprocal action of the recti and ob-
liqui on each other is one of the most beauti-

* Barclay on Muscular Motion, p. 522,

ABDOMEN. |

enable the recti to act more completely as

ful parts of the mechanism of the abdominal
muscles. This is mainly to be attributed to
the close connection which subsists between
these muscles in consequence of the formation
of the sheaths of the recti by their aponeuroses,
and the adhesion of the anterior wall of those
sheaths to the tendinous intersections of the
recti. When the recti contract, the antero-pos-
terior diameter of the abdomen is diminished,
and consequently the viscera are pushed to-
wards the sides; when, on the other hand, the —
obliqui contract, they diminish the transverse
diameter of the abdomen, and push the viscera
forward in the middle line. In the one case,
then, it will be evident that the obliqui act as
moderators to the recti, and in the other the
resistance of the recti moderates the action of
obliqui,—the former muscles being, as Cru-—
veilhier remarks, as it were, two active pillars
compressing forcibly the viscera against the an-
terior surface of the spine. It is probably to

moderators upon the several segments of the
obliqui that they are intersected by tendinous
lines, with which theaponeuroses of those muscles
are connected. Another use has been assigned
to these intersections by Bertin, viz.,—to multi-
ply the points of attachment of the obliqui
muscles, and to associate them, in many ac-
tions, with the recti muscles. This is explained
by a reference to the action of the recti in flex-
ing the pelvis: were these muscles uncon-
nected with the obliqui, they would act only
on the pelvis, into which they are inserted ; but
in consequence of the insertion of the internal
oblique into the intersections of the recti, and
the attachment of that muscle also to the crista
ilii, the force of contraction of the recti is com-
municated not only to the pubis, but also
through the fibres of the obliquus internus to
the rest of the pelvic margin.*

The action of the pyramidales seems to be
chiefly on the linea alha, which they render.
tense ; thus limiting the separation of the recti,
and opposing the tendency to visceral protru- —
sion. Fallopius supposed that they acted on ~
the bladder, especially when it was ina dis- ~
tended state; and Parsons conjectured that
they might depress the suspensory ligament of
the bladder (the urachus), and thus facilitate
the contraction of that organ.

The other muscles which are from situation
abdominal muscles in consequence of their —
connexion with the posterior wall of the abdo- —
men, are chiefly agents in the extension of the —
vertebral column: in their contracted state, —
however, they form a tense and resisting sur-—
face, against which the viscera are compressed
by the contraction of the anterior muscles.

Il. Of the Abdominal Cavity.—The annexed
engraving (fig. 5.) exhibits a view of the abde
minal cavity, the anterior and part of the lateral
walls having been cut away and the viscera
removed. The subject is so bent backward:
as to render the bodies of the vertebre

Se aa ee)

ree ree ee ee |,

= Berard, loc. cit., et Bertin, sur V’usage de
enervations des muscles droits du bas-ventre, it
Mem. de l’Acad. des Sciences de Paris. _

ABDOMEN. 19

( Fig. 5.)

rominent anteriorly, and the continuity of the
abdominal and pelvic cavities is thus clearly
shewn. It is useful to examine the relations

of the axes of these two cavities; that of the
pelvis passes forwards and upwards towards

the umbilicus, while the axis of the abdomen

_ passes from above downwards and _ forwards
"$0 as to terminate a little above the pubis,
the two axes accordingly would intersect each

_ other a little below the umbilicus at an obtuse
angle. This angle may be obliterated by
_ bringing the pelvis very much forward and
__ producing a full flexion of the spine, and hence
- in allefforts for expulsion that attitude is almost
instinctively assumed which shall identify the
_ axes of the two cavities, and thus direct the
_ efforts in the most favourable manner. The
Ordinary form of the cavity in the adult male is
_ oval, but it presents some slight differences in
_ the female and in the feetus ; and these differ-
_ ences are dependent on the great or incomplete
_ development of the pelvis. In the female the
_ abdomen is generally more capacious than in
_ the male ; and this greater size is more remark-
able at the inferior part of it in the hypogastric
__fegion. In fact in the male it would seem that
_ the great extremity of the oval is toward the

_ thorax, and its smaller one towards the pelvis ;

_ but in the female it is just the reverse, the
larger extremity being toward the pelvis. It

* Id be observed, however, that the modern

a

a

igteg

cs

.
a

re

Pa

fashion of tightly compressing the lower part of
the thorax has a material effect on the external
characters of the female abdomen, otherwise
there is no reason that the superior part of it
should be proportionally less than in the male.
In the foetus the abdomen is proportionally larger
than at any other period of life: this is to be
attributed to the imperfect development of the
pelvis, and likewise to the great size which
some of the abdominal viscera possess; and as
some time must elapse before the pelvis reaches
its full dimensions, or the viscera lose their
superfluous parts, the abdomen continues of this:
large size for a long period after birth.

The subdivision of the abdomen into regions
is especially useful in reference to the contents
of the abdominal cavity, which it is highly de-
sirable the student should examine, so as to be
able to assign to each compartment its appro-
priate contents. The abdominal viscera may
be subdivided into the membranous and the
parenchymatous; the former being such as the
stomach and intestinal canal, the latter, such as
the liver, spleen, pancreas, &c. The viscera
have likewise been distinguished in reference
to their position with respect to the peritoneum,
by the names intra-peritoneal and extra-peri-
toneal ; but it is sufficient to know that no
Serous membrane contains any organ within it
(2. e. within its sac) to see the error of such a
distinction. But we cannot adopt a better di-
vision of the abdominal viscera than that which
has reference to the functions of those organs,
and which Beclard has adopted: viz. 1. the
organs of digestion—the stomach, the intes-
tinal canal, the liver and its appendages, the
spleen, and the pancreas: 2.the urinary organs—
the kidneys and the ureters, to which may
be added from their close relation to the kid-
neys, the suprarenal capsules: 3. the organs of
generation in the male—the vasa deferentia, and
in the male foetus at the sixth or seventh month
of intra-uterine life, the testicles: none of
the organs of generation can strictly be said to
be abdominal organs in the female. In both
male and female the other internal generative
organs are pelvic viscera. If we add to the
above enumeration of parts the abdominal por-
tion of the aorta, its primary subdivision into
the common iliacs; the anterior subdivision of
these arteries under the name of external iliacs ;
the branches of the aorta which are distributed
to the viscera as well as to the walls of the
abdomen ; the common and external iliac veins;
the vena cava ascendens; the system of the vena
porte ; the abdominal portion of the sympa-
thetic system of nerves, both that which follows
the arterial ramifications, and that which is the
continuation of the chain of ganglia that lies
along the spine, the termination of the par
vagum ; the mesenteric glands, and the lacteals ;
the lymphatics and their ganglia which lie
along the spine; the origin of the thoracic duct,
a portion of the course of that duct ;—these will
complete the list of parts contained in the abdo-
minal cavity.

The full particulars of the relative positions of
the contents of the abdomen, and the abnormal

c 2

20

‘states of that cavity, both congenital and mor-
bid, including also the abnormal states of its
parietes, we prefer to bring together in a sepa-
rate article under the head Cavity aBDo-
MINAL, to which we beg to refer the reader.
The special anatomy, both natural and ab-
Boahat. of the several abdominal viscera is
‘distributed among the articles [nTEsTINAL
Cana, Kipney, Liver, Pancreas, SPLEEN,
SuPpRARENAL CaPsu_e.

BIBLIOGRAPHY.—The several systematic writers,
as Winslow, Boyer, Portal, Bichat, Meckel, Cloquet,
Marjolin, Hildebrandt, &c. for the titles of whose
respective works see the Bibliography of ANATOMY,

Introduction. )— Velpeau, Anat. Chirurgicale. Paris,
833. t. ii. Blandin, Anat. Topographique. Cru»
veilhier, Dictionnaire de Méd. et Chirurg. art. Abdo-

men. Beclard et Berard, Dict. de Médecine.
Ed. 2d. art. Abdomen. Pierer Anatomisch-
Physiologisches Realworterbuch. herausgegeben

von J. F. Pierer. Leipzig, 1816. art. Abdominal-
muskeln. Gerdy, Anat. des formes extérieures.
Paris, 1829. p. 122 and 199. Cloquet, Recherches
Anat. sur les Hernies de l’Abdomen, or the trans-
lation by McWhinnie. Lond. 1835. Scarpa, on
Hernia, by Wishart. Lawrence on ditto. Todd, on
ditto. Dub. Hosp. Reports, vol. i. F'lood’s plates of
Inguinal and Femoral Hernia. Lond. 1834. Cam-
per, Icones Herniarum. Guthrie, on Inguinal and
Femoral Hernia. A. Cooper, on ditto, and on the

Testicle. Munec, Dissertation Inaugurale sur |’ Her-
nie. 1826. Colles’s Surgical Anatomy. Dublin, 1811.
Barclay on Muscular Motion, p. 337 et sqq.

(.R. B. Todd.)

ABSORPTION in physiology (from ab-
sorbeo: Lat. absorptio, Fr. absorption, Ger.
die einsaugung, Ital. assorbimento.) The term
absorption is employed in physiology to de-
signate a vital organic function, the primary or
immediate object of which is to furnish the
system with a due supply of matter for its
growth and subsistence. It is proposed, in the
following article, first, to give an account of
the organs by which the function is performed ;
this will lead us, 2dly, to consider the question
of venous absorption; in the third place, we
shall inquire into the mode in which the ab-
sorbents act; and, lastly, we shall offer some
remarks upon the specific uses of the different
parts of the absorbent system, and upon the re-
lation which it bears to the other vital functions.

§. 1. Description of the Absorbent System.—
We propose, in the first instance, to restrict the
term absorbent system to those organs, which
are supposed to be exclusively appropriated to
the function of absorption ; these may be in-
eluded under the two heads of vessels and
glands, the vessels being again subdivided into
the lacteals and the lymphatics.

Although the absorbents are distributed to al-
most every part of the body, and perform so im-
portant an office in the animal economy, they
were among the organs which were the latest
in being discovered by anatomists. There are,
indeed, some passages in the writings of Galen,*
which would lead us to suppose that certain

* De Anat. Admin. lib. 7, sub finem; De usu
partium, lib. 4, cap. 19; An sanguis in arteriis
&c, cap. 5. :

ABSORPTION.

tts of the absorbents had been seen by

rasistratus and Herophilus, as well as by
himself; but it appears that they were, all of
them, unacquainted with the relation which
these vessels bore to the other organs, and were
entirely ignorant of their office and destination.
These scanty observations of the ancients seem
to have been entirely neglected, or even for-
gotten, until the study of anatomy was revived,
together with that of the other medical sciences,
in the sixteenth century. In the course of the
researches which were then made into the
structure of the animal body, various parts of
the absorbent system appear to have been
brought into view, and are noticed, among other
writers, by Fallopio,* who discovered the lym-
phatics, connected with some of the abdominal
viscera, and by Eustachio,t+ who detected the
thoracic duct. But although their descriptions,
especially that of Eustachio, are sufficiently
correct to enable us to identify them, as forming
a part of the absorbent vessels, yet they were
unacquainted with their specific nature and
office, and with their relation to the sangui-
ferous system. ia

It is generally admitted that the merit of the
discovery of the lacteals is due to Aselli; this
discovery he made in the year 1622. While
he was examining the abdominal viscera of
a dog, he observed a series of vessels attached
to the mesentery, which appeared to have no
direct connexion with the arteries or veins, and
which, from the circumstance of their con-
taining a white opake fluid, he denominated
Lacteals.}

He regarded them as a distinct set of vessels,
exercising a specific function, distinct from
that of the sanguiferous system, and he as-
certained that they took their origin from the
surface of the intestines, and proceeded to-
wards the more central parts of the body, but
it was not until the year 1651, that their ter-
mination in the thoracic duct was discovered by
Pecquet. §

The discovery of the other species of ab-
sorbent vessels, styled, from the appearance

* «« Observ. de Venis,” lib. 3., in Op. p. 53825
first published in 1561. We may add the names of
Fabricio, Piso, and Gassendi, who appear to have f
seen certain parts of the lymphatics, although they —
were not aware of their specific nature. See Bar-—
tholin, de Lact. Thor. c.2; and Mascagni, Vas.
Lymph. Hist. Proleg. sub init. :

t De Vena sine pari, Antig. 13, sub finem, in —
Opusc, Anat. ; first published in 1564. See Haller,

a Anat., p. 224; also Douglas, Bibliog. Anat.,

$ Dissertatio de Lactibus; first published in 1627.
See Bartholin, de Lact. Thor., c. 4; Sheldon o1
the Absorbent Syst., p. 20,1. Aselli’s work is ac
companied by plates of very rude execution, b
sufficiently expressive of the object.

§ Exper. nova anat.; first published in 1651,
Bartholin, c.5. In 1652, Van Horne publish
the first plate of the thoracic duct. ‘There is som
reason to suppose that Vesling had an imperfect vie
of it previous to Pecquet ; he published his Synta
Anat. in 1647, In describing the pancreas he spez
of the vene lactez, lately discovered by Ase
which convey the chyle to the liver, and figu
them in tab. 4, fig. 3. .

ABSORPTION.

of the fluid which they contain, the lymphatics,
was posterior to that of the lacteals. The trans-
parency of their contents rendered them less
conspicuous and less easy of detection, so that,
although certain parts of them appear to have
been seen by Fallopio, and afterwards by
_ Aselli and others, yet it was not until the year
1650, that they were distinctly recognized, and
_ their connexions ascertained. The discovery
of the lymphatic system was the subject of a
_ warm controversy between Bartholin and Rud-
_ bek, on the merits of which we are, after so
_ long an interval, scarcely able to decide. It
ai however, to have been the opinion of
_ Haller, and the most distinguished anatomists
_ of the last century, that the lymphatics were
_ detected, in the first instance, by Rudbek ;
that Bartholin had some intimation of the dis-
covery, that he then took up the subject, and
pursued it much farther than it had been done
by Rudbek.*
There is a third individual, on whose behalf
aclaim of priority has been made, which pos-
-sesses at least considerable plausibility. We
_are informed by Glisson, that an English ana-
tomist of the name of Joliffe distinctly re-
‘cognized and exhibited the lymphatics of many
of the abdominal viscera, previously to the
_alledged discovery of either Rudbek or Bar-
‘tholin.+ But even if we allow Joliffe the full
merit both of discovering these vessels, and
being aware of their specific nature, it does not
appear that he published his discovery, so that
_ it will scarcely affect the rival claims of the
former anatomists. The discovery of the ab-
sorbent or conglobate glands, as they have been
ermed, was made, for the most part, at the
Same time with that of the vessels, as a ne-
essary consequence of the intimate connexion
hich subsists between them.
_ After the existence of the lacteals had been
ly announced by Aselli, and of the lym-
jhatics by Rudbek and Bartholin, the atten-
| on of anatomists was very generally directed
| ) these organs, and discoveries were suc-
sively made, by various individuals, of the
resence of the latter in almost every part of
le body, and in connexion with almost every
ie of its organs. The labours of William and
ihn Hunter, of Monro sec., and of Hewson,
fe among the most important in their re-
Its, while we are indebted to Cruikshank,
d still more to Mascagni, for their minute
scriptions and accurate representations of the
sorbent system, in all its parts, and with its
ious relations and connexions.{

Pom.

El. Phys., ii. 3. 1; Bibl. Anat., t. i. §. 378
see 5 and Not. 4. ad §. 121. Boer. Preal.
rtholin’s statement of his claim is contained in
** Anat. Reform.” p. 621, 2; see also his trea-
, “ Vas. Lymph. Hist. Nov.” and Rudbek’s
ova Exerc. Anat.” For the historical part of the
ct we may refer to Mascagni, Prolegomena,
d t “Meckel, Manuel d’Anat. par Jourdan et
oy - t. p ch. , . 179. . 202.
| Anat. Hepat. c. 31. See Haller, Bibl. Anat.,
i, p. 452 ; also Mascagni, Prolegomena.
, the most original and correct description of
, the reader is referred to Haller, El.
xxv. 1.4..85; Mascagni, Vas. Lymph. Corp.

21

With respect to the minute anatomy of the
lacteals, we are informed that they originate
from certain small projecting bodies, termed
villi, which are attached to the interior surface
of the intestines, styled from this circumstance
the villous coat. These villi are described as
consisting of a number of capillary tubes,
which terminate with open mouths, and that
by the union of these tubes the branches of
the lacteals are composed, which are suffi-
ciently large to be visible to the eye. We must
remark, however, that although these villi, as
constituting the mouths of the lacteals, have
been minutely described, and even figures
given of the appearance which they exhibit in
the microscope, yet that considerable doubt is
still entertained of their existence, and that they
are even entirely discredited by some anatomists
of the first eminence.* Upon the whole we
may conclude that the opinion, which has been
generally adopted, respecting the capillary
termination of the lacteals, is somewhat theo-
retical, rather derived from the supposed ne-
cessity of such a formation to carry on the
functions of the vessels, than from any actual
observations that have been made upon them.

When the lacteals have acquired sufficient
magnitude to become visible to the eye, they
are seen to proceed along the mesentery, the
small vessels running together to form large
branches, and these again forming others that
are still larger, until the whole of them unite
into a few main trunks, which terminate in the
receptacle at the lower extremity of the thoracic
duct. During their progress, the small vessels

Hist., p. 1. §. 7. art. 8. tab. 1. fig. 7; Sheldon,’on
the Absorb. Syst. ch. 2. pl. 3, 4, 5; Santorini,
Tabula, No. 13. fig. 3; Magendie, Physiol. t. ii.
p. 158..0. The translation of Mascagni's work, with
copious notes by Bellini, may be advantageously
consulted ; it is not accompanied by plates. For
the lymphatics we may refer to Haller, ii. 3. 2;
Meckel, Diss. Epist. de Vasis Lymphaticis; Hew-
son, Enq., ch. 3. pl. 3, 6; Mascagni, ps. l. sect.
7. tab. 4 et seq. ; Cruikshank, on the Absorb., p.
148 et seq.; Scemmering, Corp. Hum. Fabr. t. v.
p- 388 et seq.; many of Mascagni’s plates are
transferred into Cloquet’s valuable ‘* Manuel.”
Art. ‘* Inhalation,” par Rullier, in Dict. des
Sc. Méd. t. xxv.3. Art. ‘* Lymphatique,” par
Chaussier et Adelon, ibid, t. xxix. p. 249, 200;
Meckel, Manuel, sect. 6. ch. 2; Quain’s Elem. of
Anat. p. 560..574. In Elliotson’s Physiol. ch. 9.
p- 140..2, we have a ‘short account of the first
discovery of the absorbent system.” Scemmer-
ing’s treatise, De Morbis Vasorum Absorb. con-
tains a most ample and learned catalogue of the
various works on absorption, from the earliest
period to the date of its publication in 1795.

* See Lieberkuhn, Diss. de Fabr. Vill. Intest.
passim, cum tab. 1, 2; Hewson’s Engq., c. 12,
pt. 2; Cruikshank’s letter to Clare, p. 32..4; Shel-
don on the Absor. Sys., p.32..8, tab. 1, 2; Hedwig,
Disq. Ampull. In opposition to these and other
authorities, on the affirmative side of the question,
we have the strong negative evidence of Mascagni,
whose plates do not sanction the description of
Lieberkuhn, tab. 1. fig. 1. 3; and tab. 3. fig.
1, 2,3, 5; and the decided opinion of Magendie,
Journ. de Physiol. t. i. p. 3 et alibi. On this sub-
ject see the remarks of Haller, not. 9. ad §. 91.
Boerhaave, Prel. et not. 4. ad §. 103. The ob-
servations of Du Vernoi, Mem. Petrop. t. i. p. 262
et seq., seem scarcely to have been confirmed.

22

frequently anastomose with each other, so as,
in many instances, to form a complete network
or plexus, in which respect their course differs
from that of the veins, where the small branches
unite to form the larger ones, without the lateral
communications.

The lacteals are furnished with numerous
valves, which are disposed in pairs, and have
their convex surface turned towards the intes-
tine,* so that, in the ordinary and healthy con-
dition of the vessels, their contents are pre-
vented from retrograding, and necessarily pro-
ceed from the small branches to the larger
trunks. The coats of the lacteals are thin and
transparent, and hence it is that these vessels,
except when they are filled with chyle, are so
difficult of detection. They seem, however,
notwithstanding the apparent delicacy of their
texture, to be possessed of considerable
strength, and to bear being distended far be-
yond their ordinary dimensions without being
ruptured. When they are completely filled
with chyle, and still more, when they are for-
cibly distended by injections, the number of
valves which they possess gives them a jointed
or knotted appearance, and it seems to have
been this circumstance, together with the white
colour of their contents, which first attracted
the notice of anatomists, and led to their dis-
covery. With respect to their structure, besides
the peritoneal covering which they possess in
common with all the abdominal viscera, they
seem to be composed of two distinct parts, an
internal membrane, which by its duplicature
forms the valves, and an external membrane,
which constitutes the main substance of the
vessel.

To these two obvious component parts many
authors have added a muscular coat, and some
anatomists of great respectability assert that
they have actually detected transverse fibres, in
which their contractile power is supposed to
reside. Other anatomists, however, of equal
authority, deny the existence of this muscular
coat, and, it must be acknowledged, that the
weight of the negative evidence seems to pre-
“santenng But we may remark, on the other

and, that although these transverse fibres,
constituting the museular coat, in consequence
of their transparency, or from some other
cause, have hitherto eluded our observation,
so that we have no positive proof of their
existence, the lacteals certainly exhibit what
appears to be very decided marks of contracti-
lity, and as they are not immediately con-
nected with any organ equivalent to the heart,
there seems to be no means, except their own
contractility, by which their contents can be
propelled.t See Cuyxirerovus System; Lac-
TEAL.

* These were very minutely examined by Ruysch,
Dilucid. Valvul., op. t. i. p. 1..135 they are ac-
curately described by Sheldon, p. 28.

+ Mascagni, ps. i. sect. 4. p. 26, informs us that
he could not detect the fibres; Cruikshank, on the
contrary, conceives that he has seen them in the
thoracic duct, p. 61 et alibi; and Sheldon speaks
of the muscular coat as sufficiently obvious, p. 26.
Meckel, Manuel, t. i. p. 185, does not admit their
existence ; and this is the case with Chaussier and

ABSORPTION.

‘ch. 4, 5,

The anatomical structure of the Ppt
seems to be essentially similar to that of the —
lacteals; they are composed of a firm elastic —
membranous substance, capable of consider- —
able distention without being ruptured, and
furnished with numerous valves; like the lac- _
teals they form very frequent anastomoses.
We have the same evidence of their contracti-
lity as of that of the lacteals, although we are —
perhaps still less able to demonstrate the actual _
existence of their muscular fibres. We presume
that they are likewise analogous to the lacteals
in the nature of their office, and in their desti-
nation, although they differ from them with
respect to their situation, or the parts of the
body to which they are attached ; the lacteals
being confined to the membranes connected
with the intestines, while the lymphatics are
found in almost every part of the body, and
connected with nearly all its various textures.*
They differ also in the nature of the fluid |
which they contain, for while that of the lac- —
teals, as has been stated above, is white and |
opaque, the fluid found in the lymphatics is _
transparent and colourless, so as to resemble
water, from which they have derived their spe-
cific denomination.

It is very difficult, if not impossible, to trace
the actual commencement of the lymphatics ;
but partly from anatomical researches, and
partly from physiological considerations, we
are led to conclude that they originate from
the various surfaces of the body, of all de-
scriptions, both internal and external. They
resemble the lacteals, in passing from larger
to smaller branches, which, after numerous
anastomoses, unite in a few large trunks, the
greatest part of which terminate in the thoracie ~
duct. The great trunks of the lymphatics are,
for the most part, arranged into two distinct
series, one considerably more superficial than
the other; it is observed that they generally
follow the course of the great veins, but it may
be doubted whether any direct communication

Adelon, “‘ Lymphatique,”’ Dict. des Sc. Méd. t. xxix. —
p- 256. Breschet, art. ** Lymphatique Systeme,” —
Dict. de Méd. t. xiii. p. 389, considers it doubtful.
Some curious observations were made by Desge- —
nettes, on the action of the absorbents after the
apparent death of the system, Journ. Méd. t. lxxxiv.
p- 499 et seq. Similar observations’ were after- —
wards made by Valentin, t. Ixxxvi. p. 231, et seq. 5
this action was not, however, supposed to depend
on contractility. Wrisberg informs us that he has
frequently seen spasmodic contractions in the large”
vessels and in the thoracic duct, Observ. Anat. —
Med. de Vas. Abs. Morb. in Comment. Soc. Reg.
Gotting. v. ix. § 19. p. 149. ‘3
* For the extent of the lymphatic system, see
Haller, El. Phys. ii. 3. 4, and the later account
of M. Magendie, Physiol. t. ii. p. 174, and Jo
t. i. p. 3, who conceives that absorbent vessels have
not been detected in the brain, the spine, and th
organs of sense. Dr. Alison likewise conceives tha
they have not been detected in the cranium or ner-
vous system, Outlines of Physiol. p. 76. Ma
cagni, however, appears to have detected a f
small lymphatics in the brain, tab. 27. .
Monro secundus argues in favour of their exister
but it does not appear that he actually detecte
them in any part of the nervous system; on th
Nervous System, ch. v, sect 1. and Three ‘Trea List

ABSORPTION. 23

exists between them during their course, and
we are not aware of any physiological cause of

this arrangement.
With respect to the mouths or origin of the
; lymphatics there is even more uncertainty than
; with respect to that of the lacteals; no anato-
mical investigation has hitherto been able to
detect them, and although numerous facts of
constant occurrence would seem to prove that
their capillary extremities are distributed over
all the surfaces of the body, it is from various
pathological observations and from the analogy
of the lacteals that we arrive at this conclu-

sion.*

The thoracic duct is a vessel of considerable
size, which is situated near the spine, and
which extends from about the middle of the
dorsal vertebre to a short distance above the
left subclavian vein; here it assumes an arched
form, and is bent down until it enters the vessel
near its junction with the jugular vein of the
same side.t The duct, in its passage along
the spine, is deflected in various ways, and
proceeds in a somewhat irregular or tortuous

course. For the most part it consists of a
single trunk, but occasionally there are two
trunks, either of the same or of different sizes,
and we have not unfrequently partial appen-
dages, which are added to the main trunk in
different parts of its course.{ Besides what is
properly considered as the thoracic duct, in
which all the lacteals and the greatest part of
the lymphatics terminate, a portion of these
latter, especially those which proceed from the
upper part of the body and from the superior

extremity of the right side, are generally col-

_ lected into a separate trunk, named the great

right lymphatic vessel, or right thoracic duct,

_ which is connected with the right subclavian

_vein.§~ These irregularities in the disposition

and form of the thoracic duct may be consi-
dered as in no respect affecting its physiological
uses, and to be no more than an anatomical

_ Variation of structure, probably depending

nas 6S OEE Ri aN SLi

Se ky SRA BN

sak AOR a eee hee at ied ba

hey
_ * See Magendie, Physiol. t. ii. p.175. Watson,
_ however, conceived that he had detected their open
m1 ths on the surface of the bladder, Phil. ‘I'rans.
for 1769, pl. 16. Monro, in speaking of the lym-
phaties of fishes, remarks that there is “‘ no doubt
that they begin by open mouths,” p. 30.
For descriptions and plates of the thoracic duct
following works may be referred to; Haller,
mm. Lin. c. xxv, § 565 ; Op. Min. t. i. p. 586
et tab. 11, 12; and El. Phys. xxv. 1.10..3:
_ Albinus, Tab. Vas. Chylif.; Bolius and Saltzmann,
in Haller, Disp. Anat. t. i.; Cheselden, Anat.
1. 26; Portal, Mém. Acad. pour 1770; Sabatier,
id. pour 1786; Haase, De Vas. Cut. et Intest.
bs. tab. 2. and tab. 3. fig. |; Mascagni, ps. i.
‘sect. 7. art. 8. tab. 13, 15, 19; Sheldon, pl. 5;
uikshank, p. 166..176; Magendie, Physiol t. ii.
p- 160; Meckel, Manuel, § 1698.
_ $ In Mascagni, tab. 15, we have an example of
this irregularity.
we § This is said to have been discovered by Stenon
in 1664; Meckel, Manuel, § 1703. See Haller,
Prim. Lin. § 766 and Hewson’s Enq. pt. 2. p. 61..3,
pl. 4, Cruikshank, p. 176, 7, conceives that Hew-
Son was the first who described the lymphatics of
the right i A being oe into one trunk. For
® figure of this part, see Mascagni, tab. 19. nos.
Yes, iar. 551 4

, Ag we! tt Gar

upon some mechanical cause. It is, however,
a circumstance of considerable importance in
respect to the pathological conclusions that
have been sometimes drawn from the obstruc-
tions of this organ, as well as from the experi-
ments that have been performed upon it.* The
structure and properties of the thoracic duct
appear to be similar to those of the large trunks
of the lacteals and lymphatics; its coats are
comparatively thin and transparent, yet it is
possessed of considerable strength, and is ca-
pable of being distended much beyond its
ordinary bulk; it is furnished with numerous
valves, and exhibits a great degree of con-
tractility. .

The lymphatic or conglobate glands+ com-
pose a very important part of the absorbent
system, if we may judge from their number
and their general diffusion over every part of
the body. They are of various sizes, and are
grouped together in various ways; occasionally
they are single, but more frequently connected
together in masses of considerable extent. The
are found in almost every part of the body,
always connected with the lacteals and lympha-
tics, and it is asserted that each one of these ves-
sels, in some part of its course, passes through or
is connected with one or more of these glands.
There are certain parts of the body in which
they are more numerous, and are connected in
larger masses ; the lacteals are furnished with
numerous glands in their passage along the
mesentery, while the glands that belong to the
lymphatics are found in the greatest number

and largest masses in the groin, the axilla, and

the neck. It is necessary to remark that this
account of the distribution of the lymphatic
glands applies only to the animals which belong
to the class of the mammalia; in birds they are
much more rare, and still more so in fish, while
among the lower animals, where we have sufti-
cient evidence of the existence of an absorbent
system, the glands have not yet been satisfac-
torily demonstrated.§

With respect to the structure of these glands,
as well as that of glands of other descriptions,
a controversy has long existed among anato-
mists, whether they consist of a series of cells
or follicles, as they have been termed, or whe-
ther they are composed simply of a congeries
of vessels. The question may be regarded as
still at issue; but it may be remarked that
whereas the older anatomists generally leaned
to the opinion of the. follicular structure of the

* See on this subject Sir A. Cooper, in Med.
Rec. and Res. p. 86 ct seq., and Magendie,
Journ. t. i. p. 21.

+ Some of the late French physiologists prefer
the term lymphatic ganglions, upon the principle
that the term gland more properly belongs to an
organ of secretion. ;

t Mascagni, ps. 1. sect. 4. p. 25: but this hes
been doubted by some anatomists; see Hewson, pt.2.

- 44, 5.

4 § See Fleming’s Zool. t. i. p. 338; Blumenbach’s
Comp. Anat. by Lawrence, ch. xiii. p. 256; Dict.
des Sc. Méd. art. «* Lymphatique,”’ par Chaussier
et Adelon, p. 249; Breschet, art. ‘© Lymph.
Syst.,” Dict. de Méd. t. xiii. p. 397. Hewson in-
forms us that birds have lymphatic glands in the

24

glands,* the moderns have more frequently
adopted the hypothesis of their vascular texture,
so that we may consider this doctrine as sup-
ported by the most recent and elaborate re-
searches.t See Lympuaric; GLanp.

§ 2. The question of venous absorption con-
sidered.—We have now been describing those
organs, which are more specifically or appro-
priately termed the absorbent system, as being
those parts the office of which is confined to
this operation. But a very important and in-
teresting question must now be discussed,
whether the function of absorption is exclusive-
ly performed by the lacteals and the lymphatics.

The ancient anatomists and physiologists
being unacquainted with the existence of the
lacteals and the lymphatics, yet observing the
evident effect of the operation of absorption,
ascribed these effects to the action of the veins;
and among the moderns, for some time after the
discovery of what were more appropriately
termed the absorbent vessels, it was still sup-
posed that the veins co-operated with them,
and in some cases were even the principal
agents. This was the universal doctrine until
the middle of the last century, and was one
of the points which was decidedly maintained
by Haller and his disciples.}

The arguments by which the hypothesis of
venous absorption was supported may be re-
duced to two classes, partly of a physiological
and pathological, and partly of an anatomical
nature; the first consisting of the results of
experiments performed for the express purpose
of investigating the subject, and of considera-
tions derived from the morbid conditions of
the system; the second depending more exclu-
sively upon anatomical considerations. The

neck, but that they are not found connected with the
absorbents of the abdomen, and that they are en-
tirely wanting in fish and in the amphibia; Phil.
Trans. for 1768, p. 217 et seq., and Enquiries,
pt. ii. ch. 4, 5, 6. We have the same statement
made by Monro, with respect to fish, p. 31. An-
tommarchi, on the contrary, asserts that birds, fish,
reptiles, and amphibia have ‘‘ pochissime glan-
dule ;” Prod. delle grande anat. di Mascagni, p. 8;
but the statement is made in a general way, and
without reference to any particular observations.
It would appear that no specific apparatus for ab-
sorption has been discovered in any of the inverte-
brated animals.

* We have the authority of Nuck, in favour of
the cellular structure, Adenologia, c. ii. p. 30 et
seq., fig. 9. . 12; also of Cruikshank, c. 14; and of
Abernethy, Phil. Trans. for 1776, p. 27 et seq.

+ See Hewson, v. iii. c. 2. pl. 2; Werner and
Feller, Vas. Lact. and Lymph. Descript. tab. 2;
their figures, however, appear to be exaggerated ;
Beclard, add. a Bichat, p.231; Monro tert., Elem.
v. i. p- 558. On the lymphatic glands generally
see Haller, El. Phys. ii. 3. 16..27; Boyer, Anat.
t. iii. p. 243... 257; Mascagni, ps. i. sect. 5. p. 31;
Rullier, ubi supra, p. 120 et seq.; Breschet, ubi
supra, p. 094. For plates of the glands, see Mas-
cagni, tab. 1. fig. 8...12, tab. 2. fig. 4..8, tab. 4.
fig. Me sare 8, 16, 26; Cruikshank, pl. 3; Sheldon,
tab. 3, 5.

t Boerhaave, Prelect. § 103. and § 247; Haller,
in not. 1. ad § 106, Boerhaave, Prezlect., and not. 1.
ad § 245; also El. Phys. ii. 1. 28; Monro secun-
dus, De Ven. Lymph., p. 14..21; Walter, sur la
Resorption, Nouv, Mém. Berlin, pour 1786..7, §15
et seq.; Magendie, Physiol. t. ii. p. 238.

ABSORPTION.

experiments referred to consisted in passing
injections from the veins to the absorbents, or
the reverse, thus proving, as was su ;
that a direct connexion subsisted between these
vessels. They were performed by the most
skilful anatomists of the age, and were gene-
rally acquiesced in, without either the accuracy
with which they were conducted, or that of the
conclusions deduced from them, being ever
called in question. Another class of rod
ments consisted in passing ligatures round the
thoracic duct, so as to render it impervious to
the passage of the chyle, when it was supposed
that under these circumstances the nutrition of
the animal was not interrupted,* and the same
conclusion appeared to be substantiated by
various cases of natural obstruction of the duet,
or by certain malformations of the part, where
it was either defective, or did not convey its
contents, in the ordinary manner, into the
veins. The other set of arguments, which are
more purely anatomical, were derived from the
supposed fact that various parts of the body,
which were evidently subject to the operation
of absorption, were without lymphatics, and
that this was likewise the case with large classes
of animals, the general structure of which, as
far as regards their growth and nutrition, was
analogous to that of the mammalia. Admitting
these data, it seemed to be a necessary conse-
quence that absorption must in these instances)
be performed by the veins, and hence it was
inferred that in all classes of animals, and in all
parts of the body, the veins co-operated with
the lacteals and the lymphatics in the function
of absorption.

The doctrine of venous absorption was first
formally called in question, nearly at the same
time,t by Wm. Hunter and by Monro se-
cundus,} who, as it would appear, to a certain
extent, entered upon the investigation inde-
pendently of each other. The priority of dis-
covery in this, as in so many points connected
with anatomy, was for a long time the subject
of warm controversy. We may remark con-
cerning this question, that if the judgment of
the present age should incline to ascribe to
Hunter the original conception of the hypo-
thesis, it is also disposed to allow to Monro the
merit of establishing his opinion by a skilful and
laborious process of experiment and observation.

The method which these illustrious rivals
adopted was, first, to repeat the experiments
of their predecessors, when, by noticing with
scrupulous accuracy all the circumstances con-
nected with them, they were able to demon-
strate, or at least to render it highly probable, —
that in all those cases where injections had ~
passed between the absorbents and the veins, —
either rupture or extravasation had taken place,
and that, when this was carefully guarded

a a ae, ee a re

* Some experiments of this kind are referred to
by M. Majendie, as having been performed by M.
Dupuytren, Physiol. t. ii. p. 167. See also
cherand, Elémens de Physiologie par Berard.

+t Medical Comment., passim; Cruikshank, In-
trod.; Walter, § 10 et seq.

¢ Dissert. de Sem. et Test.
t. ii. and De Ven. Lymph. Valv.

“ae

in Smellie, Thes.

a

.
?

ABSORPTION.

against, the supposed connexion between the
two sets of vessels could not be demonstrated.*
In those experiments, where the thoracic duct
had been artificially obstructed, or in the cases
where the same thing had occurred as the
result of disease or malformation, they were
enabled to detect some supplementary vessels
or some indirect channel, by means of which
the chyle had been conveyed to the veins.
With respect to the parts of the body, or
to the animals of an inferior order, which
were supposed not to be furnished with ab-
sorbent vessels, by prosecuting their examina-
tion with more care they gradually detected
the existence of these vessels in many cases
where they had not been previously known to
exist; and they were discovered in so many
new situations that it became a fair inference
that every part of the body, and every animal
whose structure is generally analogous to that of
the mammalia, is provided with an appropriate
apparatus of absorption, although, from the
texture or the peculiar nature of the vessels,
it may be very difficult actually to demonstrate
their existence. In this train of investigation
the labours of William Hunter and Monro
- were ably seconded by various anatomists, both
in this country and on the continent, among
whom we may select the distinguished names
of John Hunter, Hewson,+ Cruikshank, and

Mascagni.

* We must, however, bear in mind that we have
the high authority of Meckel in favour of the com-
munication between the lymphatics and the veins ;
** Sur Resorption,” Nouv. Mém. Acad. Berl. ann.
1770, p. 19 et seq.

The researches of some of the most accurate
among the anatomists of the present day seem also
to show that occasional communications exist be-
tween some of the lymphatics and the contiguous
veins; but this is a different kind of relation from that
which was contemplated by the older anatomists
between the sanguiferous and the absorbent systems.
This point is fully discussed by Fohmann, in his
late work, “* Sur le commun. des vaiss. lymph.
avec les veins,” where we have an account of his
own observations, as well as those of preceding
anatomists ; he conceives that the observations of
Lippi, of which an account is given in his “ Illus-
trazioni fisiol.”, are not correct: see also the
remarks of Antommarchi, Ann. Sc. Nat. t. xviii.

. 108, 9. The observations of Fohmann have

confirmed by Lauth, in his ‘‘ Essai sur les
Vaisseaux Lymph.” We may here refer to the
observations of Bleuland, which were made fifty

ago, on what he styles the arteriole lym-
phatice, by which a communication was supposed
te be maintained between the sanguiferous and
absorbent systems; see his ‘* Experim. Anat.”
Panizza of Pavia also opposes the doctrine of
Lippi; Osservazioni, c.3 and 5. Mr. Abernethy,
in examining the vascular system of the whale,
discovered certain communications between the
Sanguiferous and the lymphatic vessels; but the

__ nature of the connexion is perhaps a little doubtful ;

Phil. Trans. for 1796, p. 27 et seq. For further
information on this subject, see a lecture on the
gpa system lately published by Dr. Graves.
Mr. Kiernan, in his elaborate researches into the
anatomy of the liver, gives it as his opinion that
the doctrine of Lippi has been “ satisfactorily con-
futed”’ by Panizza; Ph. Tr. 1833, p. 729: See
Elliotson’s Physiol. p. 128,9; s. 1. also a paper in
Ann. Sc. Nat. t, 21. p. 252 et seq.

+ Phil. Trans. for 1768 and 1769; in these vo-

25

The experiments of Hunter may deserve to
be particularly noticed, because they consisted
not merely in repeating and correcting those
of preceding anatomists; but, in addition to
these, he entered upon a series of original
researches, which are highly characteristic of
that ingenuity and acuteness for which he wus
so eminently distinguished. The experiments
essentially consisted in filling portions of the
small intestines with a fluid, the sensible pro-
perties of which might be easily recognized, and
retaining it. there so as to allow of its entering
into the veins of the mesentery, were they
capable of absorbing it; the result, however,
is stated to have been that in no instance could
the fluid be detected in these veins. These
experiments appeared to have been so carefully
conducted, and so frequently repeated, as to
have impressed the minds of anatomists and
physiologists with a conviction that the lacteals
were the only vessels which are concerned in
the absorption of the chyle; and although it
was not possible to perform analogous experi-
ments on the lymphatics, yet it seemed a
natural inference, that we might extend to them
the conclusion which had been established with
respect to the lacteals.*

In proof of lymphatic absorption various
facts were brought forward, which seemed
clearly to show that when extraneous or noxious
substances were introduced into the system, it
was (lone by the medium of the lymphatic vessels
rather than of the veins; and it was thence
argued that, as these vessels perform the func-
tion of absorption under certain circumstances,
and that we are not acquainted with any other
office which they serve in the system, we may
eonclude that they are the sole agents in the
action of absorption. Although the argument,
as applied to the lymphatics, was far less
direct and conclusive than to the lacteals, yet
the analogy between the two organs appeared
so strong, and so many concurring circum-
stances appeared to favour the doctrine, that
it was very generally received, and may be
considered as having been the established
opinion at the conclusion of the last century.+

This unanimity of opinion was, however, of
very short duration ; for anatomists had scarcely
ceased to contend for the honour of the dis-
covery of the exclusive action of the lacteals
and the lymphatics in the function of absorp-
tion, when the doctrine itself was impugned
by physiologists of the first eminence, who
supported their views by a powerful train of
arguments, enforced by numerous experiments,
umes are contained his account of the lymphatics
of birds and fishes.

* Med. Comment. c. 5 p. 42..8; Cruikshank,
c. 5. p. 21.

+t See the judicions summary of opinions in
Mascagni, ps. i. sect. 2, 3: and in Rullier, ubi
supra, p. 136 et seq. The doctrine of venous ab-
sorption was, however, still maintained by many
intelligent anatomists, especially by the high au-
thority of Meckel, De Fin. Ven. et Vas. Lymph.
1772; and of Walter, Sur la Resorption, ubi
5 See particularly his general conclusion,
§ 92: he conceives that the veins are the only
agents in the absorption which is carried on at the
surface and from the cavities of the body.

26 ABSORPTION.

and by various pathological considerations.
Of these authors, one of the first, both in
point of time and of ability, is M. Magendie,
whose opinions on this subject, connected as
as they are with some of those of his most
distinguished countrymen, have been brought
forward in a form which entitles them to the
fullest and most respectful attention.

Of the two sets of observations by which
Hunter and Monro attempted to establish their
hypothesis respecting lymphatic absorption,
those derived from the analogy of the lacteals
may still be considered as maintaining their
ground ; while the conclusion which they de-
duced from their experiments has been called
in question, partly because it was thought not
to be the legitimate inference from the experi-
ments, and partly in consequence of the ex-
periments themselves having been conceived
to be imperfect or incorrect. It is principally
upon the latter ground that the force of the
objections has been rested; and it has been,
first, by repeating the experiments of Hunter,
and afterwards by varying them in different
ways, that their insufficency has been attempted
to be proved. It has been stated above that
the main support of the doctrine of the ex-
clusive action of the lacteals and the lymphatics
was derived from those experiments of Hunter,
in which it appeared that, when the circum-
stances were the most favourable for the re-
ception of substances into the veins of the
mesentery, they could not be proved to have
entered these vessels; and hence it was con-
cluded that the veins did not, under any cir-
cumstances, possess the power of absorption.

We are informed, however, by M. Magendie
that experiments have been performed by him-
self and by M. Flandrin, which afforded directly
contrary results, and that these experiments
were so frequently repeated, and varied in
such a manner, as to leave no doubt of their
accuracy.* We have here the opposing testi-
mony of individuals, both of them of the
highest authority in science, and eminent for
their skill in experimental research. From
personal considerations it might be difficult,
if not impossible, to decide between them ;
but when we take into account the circum-
stance that the experiments of MM. Magendie
and Flandrin were executed subsequently to
those of Hunter, and with the benefit of his
experience and that of the improved state of
the science during the last half century ; when,
moreover, we are informed that the experiments
of the French physiologists were more nu-
merous than those to which they were opposed,
and that their results were uniform and un-
equivocal, we can scarcely refuse our assent
to the conclusion, that the experiments of John
Hunter do not afford a sufficient foundation
for the doctrine of the non-absorption of the
veins.

But the French physiologists have not sa-
tisfied themselves with repeating the experi-
ments of Hunter; they have extended them

* Physiol. t. ii, p. 181 et seq.; Journ. Méd.
t. Ixxxv. p. 872 et seq., and t. Ixxxvii. p. 221.
et seq., and t. cx, p. 73 et seq.

in various ways, and have obtained results — .

supposed to be still more decisive in favour

of venous absorption. Among the most im- —

portant, or at least the most curious of these,
is an experiment which was performed by
M. Magendie, in conjunction with M. Delille,
and which was conceived by these physiolo-
gists to afford the most unequivocal proof of
their hypothesis. It consisted in dividing all
the parts of one of the posterior extremities
of a living animal except the artery and the
vein, and in applying to the foot a poisonous”
substance; when, in the short space of a few
minutes, the effects of the poison on the func-
tions of the animal were most distinctly ap-
parent.* It was argued that in this case there’
was no mode of communication by which the
poison could be conveyed from the extremity
to the centre of the system except the vein,
and that, therefore, the vein must have acted
as. the absorbing vessel. The experiment was
rendered more striking, and, as was conceived,
more conclusive, by dividing the bloodvessels
themselves and introducing metallic tubes
between the divided ends, through which alone
the two currents of the arterial and. venous
blood respectively could pass in forming the
communication between the extremity and the

trunk of the animal, yet, under these appa--

rently unfavourable circumstances, the delete-
rious effects were manifested on the system
as in the former case.t Experiments of this
description appear to have been sufficiently
multiplied to establish the fact, that the poison
in these cases passed along the vein, and was
conveyed in the general mass of the blood.
The result of these experiments is no doubt
very remarkable, and what would scarcely
have been anticipated ; yet we may remark,
that there is one circumstance connected with
them, which, in a great measure, invalidates the
conclusion that has been supposed to follow so
necessarily from them. It may be inferred
from the expression made use of, that the
poison employed, which was the extract of
the upas tree, was inserted by a puncture or

incision into the foot of the animal, and would, .

therefore, in the first instance, be mixed with
the blood ; so that the only deduction which we
are warranted to draw from the experiment is,
that the venous blood, being infected with the

poison, had the power of communicating the -

infection to the system at large.t On this

view of the subject we should not regard the

above as a case of absorption, but merely as
an instance of the power of extraneous sub-
stances, under certain circumstances, of uniting

with the venous blood and retaining their

specific properties.

In connexion with these experiments of —
M. Magendie and his associates, we have

another series which were performed by MM.

Tiedemann and Gmelin, and which bear di- —
rectly upon the question of venous absorption. —
Their object was to ascertain whether there

* Magendie, Journ. t. i. p. 25..7.

{ Journ. t. i. p. 23 et seq. ; Elem. t. ii. p. 183.. 5. ;
{ See Rullier, ubi supra, p. 150..2: and Adelon,

** Absorption,’’ Dict. de Méd. t. i. p. 148, ~

Se ee ee ee ee

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AE A RS Ee NS fae RS et

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ABSORPTION. a

was any direct communication between the
organs of digestion and the bloodvessels except
by means of the lacteals. For this purpose
they mixed with the food of an animal various
substances, which by their colour, odour, or
other sensible and physical properties, might
be easily detected in the fluids of the body.
After some time the animal was examined, and
the result was that unequivocal traces of the
substances were not unfrequently detected in
the venous blood and in the urine, while it
was only in a very few instances that any in-
dication of them could be discovered in the

-chyle. The colouring matters employed were

various vegetable substances, such as gamboge,
madder, and rhubarb ; the odorous substances
were camphor, musk, assafcetida, &c.; while,
in other cases, various saline bodies, such as
muriate of barytes, acetate of lead and of
mercury, and some of the prussiates, which
might be easily detected by chemical tests,
were mixed with the food. The colouring
matters, for the most part, were carried out
of the system without being received either
into the veins or the lacteals; the odorous
substances were generally detected in the
venous blood and in the urine, but not in
the chyle, while of the saline substances many
were found in the blood and in the urine, and
a very few only in the chyle.*

The conclusion, which we are disposed to
regard as the fair inference, from the facts and
arguments that have been adduced on the
subject of venous absorption, is that, although
there are strong analogies and various patho-
logical considerations which would induce us
to confine the function of absorption to the
lacteals and the lymphatics, yet that the result
of the experiments, although not uniform, is
upon the whole in favour of venous absorption.
It only remains for us to inquire how far the
State and actions of the parts on which the

experiments were made, were so far neces-

sarily deranged by the process to which
they were subjected as to render the results
inapplicable to the natural condition of these
organs. Now this certainly appears to be the
case in the experiments of MM. Magendie
and Delille, where the poisonous substance
Was introduced into the blood; and the same
remark may probably be applied to a number

of pathological occurrences that have been

D supposed to afford a proof of venous absorp-

tion, such, for example, as the case of ulcerated

surfaces, where pus has been detected in the
veins, and still more extraneous bodies, which

& may have been either accidentally or designedly

inserted into the ulcerated part.t But it is

_* Ed. Med. Journ. vol. xvii. p. 455 et seq.
On the absorption of foreign bodies see the early

__-—«sexperiments of Lister and Musgrave, Ph. Trans.
_ for 1683 and 1701; also Lowthorp’s Abrid. vol. iii.

p- 10)..5, and La Motte’s Abrid. par. 2. ch. iv.

W p- 75,6; with Haller’s sanction of their accuracy,

. Phys. xxiv. 2.3; see also J. Hunter, in Med.
Com. p. 44 et seq., and Cruickshank, ch. viii.
On the other hand, the experiments of M. Magendie
and his friends would lead us to form an opposite
conclusion ; Elem. t. ii. p. 168, 9. See Elliotson’s
Physiol. p. 126.

+ See the experiments of Mr. Key, in Med.
Chir. Trans. vol. xviii, p. 212, 13.

not unreasonable to suppose that in these in-
Stances, in consequence of the erosion and
partial destruction of the organs, the small
branches of the veins will present an external
orifice, through which the pus or other ex-
traneous substance may be immediately re-
ceived into the sanguiferous system, nearly
upon the same principle as in the experiments
related above.

The experiments of MM. Magendie and
Flandrin, the results of which were so opposite
to those of Hunter, do not indeed lie open to
the same objection; but even here there is
perhaps some ground for inquiry, before we
implicitly adopt the conclusion that has been
deduced from them. The experiment, as origi-
nally performed by Hunter, necessarily implies
a degree of mechanical violence, which must
produce a considerable derangement of the
actions of the parts concerned. Acute inflamma-
tion of a peculiarly irritable and sensitive organ
must have ensued, the vessels of all descriptions
must have become much distended ; rupture
and extravasation may have been not an impro-
bable consequence of this inflammation and
distention, and, in short, a general derangement
both of structure and functions may have oc-
curred, which must prevent us from drawing
any positive inference respecting their natural
condition.

These observations will apply with much
greater force to a subsequent variation of the
experiment, which consisted in entirely detach-
ing a portion of the intestine from the remainder
of the tube, and filling this divided portion with
the fluid, which, as in the former case, was
detected in the vein of the mesentery. This
arrangement was supposed to afford a still more
decisive proof of venous absorption than the ex-
periment in its original state, and if we con-
sider the mechanical disposition of the organ
only, we may admit that this would be the
case. But it is obvious, on the other hand, that
the vital actions of all the parts concerned must
have been much more deranged, and that, on
this account, we ought to be proportionally cau-
tious in the application of such experiments to
our physiological theories.

We would venture to suggest, that the re-
markable discrepancy which exists between the
experiments of Hunter and of the French phy-
siologists may perhaps be reconciled, by having
recourse to the supposition, that in the former
case there was less violence used to the parts,
and that they were left more in their natural
condition ; whereas M. Magendie, as we pre-
sume, from a desire to render the effect more
certain or more decisive, either produced a
greater degree of distention of the intestines,
or, in some other way, caused a greater derange-
ment of the parts, so as to produce a difference
in the results. But this idea is offered merely
as a conjecture, from which we do not venture
to deduce any of our conclusions.

Upon the whole we feel disposed to regard
the experimentsof MM.TiedemannandGmelin,
and those of an analogous kind, in which extra-
neous substances were found in thevenous blood,
and in some of the secretions, when they could
not be detected in the chyle, as more directly

28 ABSORPTION.

favouring the doctrine of venous absorption,
because they are free from the objection which
must always attach to those operations, where
any considerable degree of mechanical violence
has been employed. It may indeed be ob-
jected, that in these cases, the examination of
the body did not take place at the proper point
of time; that, in some instances, it was made
at too early a period, before the extraneous
body had time to enter the lacteals, and, in
other cases, not until it had left them, and had
been discharged from the thoracic duct into the
veins. But this contingency must be regarded
as rather a possible than a probable occurrence,
and it is obvious that if any considerable num-
ber of experiments were performed, we can
scarcely suppose it to exist.

The conclusion that we are disposed to draw
from all the facts and arguments that have been
brought forwards on the subject is in favour of
the possibility of venous absorption, at least
under peculiar circumstances ; at the same time
that there are strong anatomical considerations,
which would induce us to suppose, that in the
ordinary actions of the system, the function of
absorption is confined to the lacteals and the
lymphatics.*

§. 3. Inguiry into the mode in which the ab-
sorbents act.—In entering upon this inquiry
there are two distinct subjects which present
themselves for our consideration ; we must first
ascertain by what means the substances that are
absorbed enter the mouths of the vessels, and,
in the second place, after they have entered the
mouths, how they are conveyed along the ves-
sels themselves.

With regard to the first of these points we
may remark, that while there is so much uncer-
tainty respecting the anatomical and physio-
logical structure of the mouths of the lacteals,
and still more, while we are completely igno-
rant of that of the lymphatics, we cannot ex-
pect to arrive at any definite conclusion con-
cerning the mode of their action. We may,
however, venture to say, that there is strong
reason to believe, that the absorbents terminate
in very minute or capillary vessels, that have
open mouths, and that these mouths are brought
into contact or close approximation with the
substances to be absorbed. Hence, by an ana-
logy, which it must be acknowledged is some-
what vague, the action of these minute vessels
has been referred to capillary attraction. But

* A summary of M. Magendie’s experiments and
deductions is contained in his Journ. t. i. p. 18 et
seq. and his Elem. t. ii. 238. .243; on this subject
see also Bichat, Anat. Gén. t. ii. 104, 5, with the
remarks of Beclard, p. 130. We must not omit to
notice the experiments of M. Ségalas, who by
dividing the bloodvessels of a portion of the intes-
tine, and leaving the lacteals, thus, as it were, re-
versing the experiments of M. Magendie, found that
no absorption took place, and hence concludes that
the lacteals do not possess this power ; Magendie’s
Journal, t. ii. p. 117 et seq. So singular a conclu-
sion must,we conceive, lead us to place but little con-
fidence in the result of such complicated experiments.
Franchini of Bologna thought that the lymphatics
absorb “‘ la sostanza assimilabile,” but that the sub-
stances which do not directly contribute to nutrition
are absorbed by the veins; Consider. Fisiol. sull’
Assorb. p. 44,

it may be doubted whether in this inference, as
in so many other cases of physiology, we have
not been misled by a mere nominal resem-
blance, and have applied the term capillary to
the action of the lacteals, because it had been
used to denote their dimensions. Perhaps,
strictly speaking, there is scarcely a single cir-
cumstance, in which the action of the lacteals
can be assimilated to that by which fluids are
taken up by capillary tubes. The structure
and consistence of the tube itself, the nature of
the substance on which it is supposed to act,
and their relative situation, are all of them
more or less different from what occurs in the
ordinary cases of capillary attraction. And if
there is a difficulty with respect to the lacteals,
where we have at least some indistinct evidence
of the mechanical disposition of the parts, which
may seem favourable to this hypothesis, in a
much greater degree will it exist with respect
to the lymphatics, where we have nothing to
direct our opinion, except the analogy which
may be presumed to exist between the two spe-
cies of absorbent vessels.

In consequence of these difficulties, and of
the supposed inadequacy of the mechanical
theory, many physiologists have had recourse
to a certain specific action of the vessels, and
have conceived that the chyle was taken up by
a power, which has been supposed to be ana-
logous to an elective attraction between the
vessel and the substance that is absorbed.*
There are indeed many circumstances which
would appear to indicate, that a certain kind of
selection is exercised by the mouths of the
vessels, for, as far as we are capable of judging,
when substances possessed of the same con-
sistence and physical properties are placed in
contact with these mouths, some of them are
received, while others are rejected. But we
must remark, that the same objection may be
urged against this as against the former expla-
nation, that the term elective, which is borrowed
from the chemical relation of bodies to each
other, is perhaps as little applicable to the case
under consideration as that of capillary, which
refers more to their mechanical action.

Discarding therefore all these analogical
illustrations, which are at least of doubtful
application, we may remark, that the lacteals
ought to be regarded, like every other part of
the animal frame, as vital organs, possessed of
appropriate and specific powers; that, in this
instance, we are not able to refer to any general
principle the train of events now under con-
sideration, and that we must therefore be satis-
fied with simply stating the fact, that the lae-
teals have the power of taking up by their
extremities certain substances, with which they
are in close approximation ; that, for the most
part, the substances which they receive are the
elements of the chyle, that they select these

from the contents of the intestinal canal, and —

* See Bichat, Anat. Gén. t. ii.
Physiol. t. ii. p. 397, 8; Young’s
Bell’s Anat. v. iv. p. 290. M. Magendie, however,
is disposed to reject all these hypothetical explana-
pica Elem. t. ii. p. 162,3, and Journ. t. i. p. 3.
et alibi. :

. 125; Dumas, —
ed. Lit. p. 112 ;

ABSORPTION. 29

that, except under peculiar circumstances, they
reject every other substance.*

When the elements of the chyle have been
received into the lacteals, it appears to undergo

a certain degree of elaboration, by which it is’

farther assimilated and perfected, an operation,
the intimate nature of which we are unable to
explain, but which, as well as its entrance into
the mouths of the vessels, we correctly refer to
their vital action. After the chyle has entered
the lacteals, there is less difficulty in conceiving
the subsequent steps of the process. We are at
least able to generalize the operation, by referring
it to contractility, the same power which ori-
inates motion in other parts of the system.
t must, no doubt, be admitted, that the exis-
tence of the muscular fibres of the lacteals has
not been satisfactorily demonstrated, and that,
_ until this has been accomplished, our opinion
can only be regarded as hypothetical : but we
have here the advantage of being able to assign
a probable and sufficient cause of the effect,
and are aware of the point towards which we
must direct our future investigations.t Before
we conclude this branch of the subject, we may
remark concerning the contents of the lacteals,
that, under ordinary circumstances, we have
no decided proof of these vessels containing
any substance except the elements of the chyle,
and that, although in some of the experiments
referred to above, extraneous bodies have been
occasionally found in them in minute quantity,
these cases must be regarded as exceptions to
the general fact.
With 2 gi to the chyle itself, it has been
a subject of examination by the chemists, whe-
ther its properties are always uniform in the
same animal, or class of animals, under the
various circumstances of age, constitution, and
still more of diet, to which they are subject.
But it may be necessary, before we enter upon
this inquiry, to premise a few remarks upon
the meaning of the terms chyme and chyle.
By the older physiologists they were very gene-
ly employed as synonymous, and this is still
the case with some of the modern writers, more
especially on the continent.{ A clear distine-
tion between them has, however, been pointed
_ Out and recognized, and as there appears to be
_ an essential difference between them, it is desi-
_ fable that it should be generally adopted. The
first of these substances is the immediate pro-
_ duet of the action of the gastric juice on the
_ aliment, as received into the proper digestive
_ stomach, while the latter is the substance which
is produced by a subsequent part of the pro-
_ cess of digestion. The conversion of chyme

__ ™ See the remarks of MM. Chaussier and Ade-
lon, ubi supra, p. 272 et seq.; also Adelon,
Physiol. t. iii. p. 85 et seq.; and Alison’s Out-
lines, p. 79.
+ This is essentially the doctrine of Haller, Prim.
c. xxv. §.568. Sheldon, p. 28, and Cruik-
— c - = tm oare hie this nie 2 but it
opposed e high authority of Mascagni, ps. i.
sect. 4. p. 24, 8. ; fs a
¢ This appears to be the case with M. Rullier,
art. “* Chyme,” in Dict. de Méd. t. v. p. 241.. 4;
M. Adelon, however, clearly marks the distinction,
Physiol. t. iii. p. 25, et alibi,

into chyle seems to commence shortly after it
leaves the stomach, and while it still remains
in the duodenum, is so far advanced as to be
reduced into a condition proper for being re-
ceived into the lacteals. There is, however,
reason to believe that the completion of the
process takes place in the lacteals themselves,
and even that it is not until the chyle arrives at
the thoracic duct, or at least at the great trunks
of the lacteals, that it is fully elaborated. The
nature of the change which the chyme expe-
riences in the duodenum, and the agents by
which this change is effected, what share the
secretions of the part itself, the bile, or the
pancreatic juice have in the operation, are
questions that still remain in discussion, and
which will be considered in the appropriate
parts of this work.*

For the analysis of the chyle we are prin-
cipally indebted to Vauquelin, Marcet, and to
Dr. Prout. Vauquelin employed the chyle
of the horse, as taken from the large trunks
of the lacteals and from the thoracic duct.+
The experiments of Marcet were principally
directed to the inquiry, how far the chyle of
the same kind of animal was affected by dif-
ferences in the diet, according as it consisted
principally of animal or vegetable substances.
Dr. Prout’s experiments on the chyle extended
both to its general properties, and to the dif-
ferences produced by different kinds of diet,
while, in addition to these points, he entered
into a very interesting examination of the suc-
cessive changes which it experiences, from its
first entrance into the lacteals until its final
deposition in the thoracic duct.§ The result of
these experiments, as far as our present inquiry
is concerned, tends to shew that the vegetable
chyle differs somewhat, in its physical and
chemical properties, from that of animal origin,
and that the chyle, when it first enters the
lacteals, is in a less perfect state, while it be-
comes more assimilated to the blood in pro-
portion as it advances towards the thoracic
duct.

With respect to the means by which the
animalization of the chyle is perfected after it
enters the vessels, we have no certain informa-
tion, and we have scarcely any analogy which
may assist in guiding our opinion. What is
termed by modern physiologists the action of
the vessels, by which so many operations of the
animal economy are supposed to be effected,
we may regard rather as an expression which
serves as a convenient veil for our ignorance,
than as throwing any light upon the process.
We have no evidence that any addition is made
to the chyle while in the lacteals ; and indeed
we can scarcely suppose it possible that this is
the case, so that the only conceivable effect of
this action is reduced to the motion which is
imparted to the chyle by the alternate contrac-
tion and relaxation of the vessels, in conse-

* See the remarks of Adelon, art. “ Chyliféres,”
Dict. de Méd. t. v.

+ Ann. Chim. t. Ixxxi. p. 113 et seq.; Ann. Phil.
v. ii. p. 220 et seq.

¢ Med. Chir. Trans. v. vi. p. 618 et seq.

§ Ann. Phil. v. xiii. p. 22..5.

30

quence of which the constituents may be more
completely mixed together, and to a certain
degree of pressure and temperature to which it
is exposed, which may modify any spontaneous
change that might otherwise take place in the
arrangement of its elements. But to whatever
cause it may be referred, we must consider the
chemical and physical change in the nature of
the chyle as one effect produced by the lacteals,
as well as the progressive motion which is im-
parted to their contents.

In the present state of our knowledge on the
subject, it remains for us to consider whether
we have any independent evidence of the exist-
ence of the muscular fibres of the absorbent
vessels, whether, if their existence be proved,
and their contractility thus established, it
would be necessary for us to search out for
other causes of the effects, and lastly, to what
other principle the acknowledged effects might
be attributed, should it appear, upon full con-
sideration, that the assigned cause 1s insufficient
or inadequate.

The above considerations lead us to give an
account of the hypothesis of the action of the
absorbents, which has been proposed by M.
Magendie. He had ascertained, by a previous
train of experiments, that according to the con-
dition of the system as to depletion or plethora,
the process of absorption was respectively acce-
lerated or retarded. Hence he draws the con-
clusion, which, however, we conceive not to be
a necessary consequence of the premises, that
the function depends on a mere mechanical
principle, independent of any vital action. The
mechanical principle to which he has recourse,
and which he thinks can alone account for the
effect, is that of capillary attraction; but this he
conceives not totake place from the open
mouths of the vessels, according to the ordinary
conception of the subject, but that the fluid is
imbibed by the substance of the vessel itself,
and is, as it were, filtered through its pores.*
He explains its further progress by supposing,
that when it has entered these pores, it is car-
ried forwards by the current of the fluid pre-
viously im the vessel.

To prove his idea of the permeability of the
parietes of the vessels, he instituted a series of
experiments on the veins of an animal shortly
after death, when he found that they were
capable of imbibing and transmitting certain
fluids with which they were placed in contact.
Still farther to substantiate the hypothesis,
M. Magendie repeated a set of analogous ex-

eriments on the vessels of a living animal.
hey consisted essentially in detaching a por-
tion of one of the great veins, and applying to

* Journ. t. i. p.6 et seq. and Dict. de Méd.
et Chir. Prat. ‘ Absorption,” t. i. p. 91 et seq.
The doctrine of transudation was maintained by
many of the older physiologists ; see Kauw Boer-
haave, de Persp. ; also Haller, El. Phys. ii. 2. 23;
more lately it was supported by W. Hunter, Med.
Com. ch. 5; by Walter, ubi supra, § 28..35; and
by Mascagni, ps. 1. sect. i. andis zealously main-
tained by his commentator Bellini, t. i. not. 4,
p-33..0. The “ pénétrabilité” of the cellular tex-
ture was one of the fundamental doctrines of Bordeu,
Recherches sur le Tissue muqueux, $ 72.

ABSORPTION.

its surface the solution of some narcotic or
poisonous substance, the effects of which were,
in a short time, manifested in the system at
large.*

This doctrine of imbibition and transudation
has been embraced by M. Fodéra, who has
endeavoured to confirm the opinion of M. Ma-
gendie by additional experiments, which he
conceives tend directly to prove that the vessels
of the living body possess this power of im-
bibition. The method which he adopted to
prove this point, in the most unequivocal man-
ner, was to inject into two separate cavities of
the body two fluids, which by their union pro-
duce a compound, the presence of which may
be easily detected, and which could be formed
by no other means except by this union. For
example, into the cavities of the pleura and
the peritoneum were respectively injected the
solutions of the ferro-prussiate of potash and of
the sulphate of iron, when it was found, after a
certain length of time, that various membranes
and glands, connected with the thorax and the
abdomen, were tinged with a blue colour.

M. Magendie afterwards performed an ex-~
periment, which seemed more directly to bear
upon the question, where a solution of the
ferro-prussiate was retained in a portion of the
intestine, at the same time that its external
surface was placed in contact with a solution
of the sulphate of iron: the part was then ex-
posed to the galvanic influence, the result of
which was that a blue tinge was communicated
to the sulphate. Weare further informed, that
according to the direction of the galvanic cur-
rent, the blue colour was produced either in
the sulphate or in the ferro-prussiate. From
these experiments M. Fodéra draws the con-
clusion, that the processes of absorption and of
exhalation may be referred to the mechanical
operations of imbibition and transudation, which
take place through the pores or capillary open-
ings of the various textures of the body.t

On these experiments, and the conclusion
deduced from them, we shall remark, that the
facts appear to prove that membranes, perhaps
during life, and certainly after death, before
any visible decomposition has taken place, are
capable of transmitting fluids through their tex-
ture; but we conceive that the analogy between
this case and that of the entrance of chyle into
the lacteals is so incomplete, that we can draw
no inference from the one of these events which
can be fairly applied to the other. Both the
mechanical and the physiological properties of
membranes and vessels differ much from each
other, while the nature of the fluids employed in —

nal

oT

* Journ. t. i. p. 9, 10. 3

+ ‘* Recherches sur l’Absorption et l’Exhalation,”
and Magendie’s Journ. t. iii. p. 35 et seq. ; see, also —
Med. Repos. v. xix. p. 419, et Med. Journ. v. xix, —
p- 488, 9. On this subject see the remarks F
Tiedemann, Traité de Physiol. par Jourdan, § 168. —
p. 242. Mr. Mayo remarks, that the principle of
imbibition and transudation affords a more easy ex- —
planation of the experiments of MM. Magendie
and Ségalas, than that of venous absorption; Phy- —
siol. (3rd ed.) p. 97 et seq. See the remarks and —
objections of Sir D. Barry, Exper. Research
p- 80..2 et alibi; also Elliotson’s Physiol. p.

he

ABSORPTION.

the experiments is totally different from any
thing to which the parts are exposed under
ordinary circumstances. It may be further
remarked, that if the texture of the vessels is so
permeable to fluids of all kinds and in all
directions, it is difficult to conceive of any
cause which can retain them there when they
have entered, and which should prevent their
escaping through the same pores when any
ressure is made on the contents of the vessels
y its contractile power or by any extraneous
force.

And it may be further remarked concerning

___ these experiments, without impugning the accu-
___— racy or the dexterity of the operator, that they
8 imply a degree of minuteness in the execution,
¢@ of attention to a variety of concurrent cir-
___- cumstances, and are altogether of so extremely

____ delicate a nature, as to render it undesirable that
___ any physiological conclusion should be founded

on them. If a single bloodvessel be divided,
however minute, and its extremity be exposed,
or even if a single cell of the membranous
texture be laid open, so as to admit of the
___ introduction of the fluid, the essence of the
| experiment is destroyed, and its results must
become equivocal.

Another hypothesis respecting the nature of
absorption has been lately brought forward by
Sir D. Barry, according to which it immediately
depends on atmospheric pressure, either ex-
ercised directly on the surface of the body, or
acting indirectly on the absorbents through the
medium of the great internal cavities. The
experiments on which the hypothesis rests con-
sisted in introducing a portion of some poison-
ous substance into a wound, and forming a
_ vacuum over it by means of a cupping-glass ;
_ when, by contrasting the effect of the poison in

this case with that which ensues from the same
application where the cupping-glass was not
employed, he concludes that the process of ab-
_ sorption was suspended by removing the at-
_ mospheric pressure, and he hence infers that
_ this pressure is the cause of absorption.*

_ The results of these experiments, in a prac-
tical point of view, are of great interest, but
_ with respect to the physiological conclusion that
has been drawn from them, there are various
_ Circumstances to be taken into account, which
ae not to have been duly attended to.
In the first place, a similar kind of objection
occurs in this case as in the experiments of
MM. Magendie and Delille related above, that
the poison was introduced into a wounded
part, and would therefore be immediately mixed
ee h the blood and carried into the general
circulation. The effect of a vacuum formed
_ over the divided extremity of a vessel, must be
to retard the progress of its contents, whatever
_ be its description, or in whatever cause it ori-
8 es. This effect is therefore not specifically
_ applicable to absorption, even in the natural
State of the parts; and when we consider that
in this case there was an artificial opening

hy Barry’s Exper. Researches, pt. 2 “On Ab~«

a sige ;” Alison’s Outlines, p. 85; Bostock’s Phy-
- siol. v. ii. p. 593 et seq.

ees ee > mv

MBER Mien est

31

made into the vessel, we may venture to affirm
that the conclusion which was drawn from it is
in no respect the necessary inference from the
facts.

And besides this general objection, it may be
fairly questioned how far the removal of pres-
sure from the surface of the body could act in
retarding the progress of a fluid along a vessel
which has no external opening, and which is
provided with valves, such as is strictly the
case with the lacteals, and may be almost said
to be so with the lymphatics. And with re-
cae to the lacteals, it appears a very obvious
objection to the hypothesis, that they are alto-
gether defended from the effects of atmospheric
pressure, either as applied directly, or as in-
directly acting on them through the medium of
any of the internal cavities. Besides, we have
sufficient proof of the spontaneous and inde-
pendent action of these vessels, whatever may
be our opinion respecting the existence of their
muscular coat, and to whatever principle we
may refer this action, and we have thus an
actual cause for the propulsion of their con-
tents, although it is impossible to estimate its
actual amount, it would appear unnecessary to
search for any farther agent, unless we have
good ground for concluding that the existing
cause is inadequate to produce the effect re- .
quired.

Cutaneous absorption.—There is a branch
of the subject to which we must now direct
our inquiry, the existence and extent of what
has been termed cutaneous absorption. When
we trace the progress of the lymphatic vessels
from their great central trunks, and follow them
through all their minute ramifications, we find
that many of them appear to have their origin
from the surface of the body,* and hence we
are led to suppose that the function of ab-
sorption is exercised, to a certain extent, by the
cutis, or the parts immediately connected with
it. That this is the case is proved by various
pathological facts; we have daily opportunities
of observing, that various medicinal substances,
by mere application to the surface, and still
more when aided by friction, produce the same
effect upon the system as if they had been
received, in the ordinary way, through the
medium of the stomach. By this means
mercury manifests its specific action on the
salivary glands, the salts of lead destroy the
contractility of the muscular fibre, while opium,
tobacco, and other narcotics produce their pe-
culiar effects on the nervous system.

But, besides this kind of absorption, which
is brought about by the substances being, as it
were, mechanically forced into the pores of the
skin, and thus applied to the mouths of the
lymphatics, it was an opinion very generally
embraced by the older physiologists, and still
retained by many of our contemporaries, that
the lymphatics, which are distributed over the
surface, possess the power of imbibing water,
when simply applied to it by the immersion
of the body, or even when it is exposed to

* See Haase, De Vas. Cut. et Intest. Absorb.,
tab. fig. 2; also, Mascagni, tab. 2, fig. 9. . 28, tab. 3.

32

aqueous vapour diffused through the atmos-
phere. This supposed power of cutaneous ab-
sorption was called in to account for various
physiological or pathological facts, for which
it appeared to afford a plausible explanation,
while, on the other hand, the easy mode in
which it appeared to account for these facts
was made use of as the great argument to
prove its existence. The statical experiments
of Sanctorius, which have, since his time,
been so much multiplied and extended, were
supposed to prove unequivocally that the body
is capable of gaining weight independently of
any substance received into the stomach, and
to account for this addition, recourse was
always had to the cutaneous absorption. Of
late, indeed, it has been discovered, that a part
of the effect ascribed by Sanctorius to the
action of the skin is in reality due to the lungs,
but still, after making the necessary deduction
for the operation of the latter organ, there re-
mained a certain increase of weight, which it
was supposed could only be accounted for by
admitting the existence of the cutaneous ab-
sorption.*

The doctrine of cutaneous absorption has,
however, been altogether called in question by
Seguin, who performed a series of experiments,
which consisted in immersing a part of the
body in a saline solution, for example, that of
corrosive sublimate, the effects of which on the
system at large would be easily recognized,
if any part had been absorbed. The result
was, that when the cuticle was entire, no effect
that could be attributed to absorption took
place, and the conclusion seemed not unna-
tural, that under ordinary circumstances it did
not exist.¢ Currie was led to form the same
conclusion by accurately weighing the body
before and after immersion in the warm bath,
under circumstances which were conceived to
be favourable to the process,{ and as the re-
sults of his experiments coincided with those
of Seguin and others, the doctrine of cuta-
neous absorption, except under the particular
circumstances mentioned above, was very
generally abandoned. Experiments have been
adduced to prove, that even under these par-
ticular circumstances, when substances are ap-
plied by friction to the surface, they do not
enter into the mouths of the vessels, but being
volatilized by the heat of the body, that the
vapour thus produced is inhaled by the lungs ;§
an opinion which one might be inclined to
think was almost too extravagant to be seri-
ously maintained.

The subject of cutaneous absorption has
been lately investigated by Dr. Edwards, with
that skill and address which he has applied to
so many departments of physiology. By a
number of experiments, which were performed
on cold-blooded animals, where it was more

* Mascagni, p. 22, 3; see also Kellie, in Ed.
Med. Journ. v. i. p. 170 et seq.; and the article
** Integuments” i Rees’s Cyclop.

t Fourcroy, Méd. Eclair. t. iii. p. 232. . 241, and
Ann. Chim. t. xc. p. 185 et seq.

${ Med. Reports, ch. xix.

§ Ed. Med. Journ. v. ii. p. 10 et seq.

ABSORPTION.

easy to observe the effects, he found that ab-
sorption was carried on, to a considerable
extent, when the animal, or a part of it was
immersed in water. The conclusion which
the experiments seemed to warrant was, that
gauebebitien and absorption are, at all times,
going forwards at the surface, but that the
operations proceed at different rates, according
to the circumstances in which the animal is
placed, and that the body gains or loses weight,
in proportion to the excess of one of them
above the other. The analogy of the cold-
blooded animals he applies to those with warm
blood, and he supposes that they are subject
to the same double action, a conclusion which
appears to be confirmed by some experiments
that were performed on guinea-pigs immersed
in moist air, when an increase of weight was
found to have taken place, which, after taking
every circumstance into consideration, seemed
necessarily to depend on absorption.* With
respect to the experiments of Seguin, Dr. Ed-
wards is not disposed to call their accuracy in
question, but he points out various circum-
stances connected with them, which he con-
ceives would tend to increase the transudation,
and to diminish, or even entirely to suspend
the absorption.t The experiments of Dr. Ed-
wards, considered in all their relations, are
generally conceived to decide the question
respecting the existence of cutaneous absorp-
tion, under the ordinary circumstances, and in
the natural conditions of the system.

§. 4. Of the specific uses of the different
parts of the absorbent system, and of the rela-
tion which that system bears to the other vital

JSunctions—W hatever opinion we may form on

the controverted question respecting venous
absorption, and in whatever manner we may
explain the action of the lacteals and the lym-
phatics, there can be no doubt that their spe-
cific use is to absorb certain substances which
are presented to their extremities.{ There is,
however, so well marked a distinction between
the situation and the anatomical relations of
these two kinds of vessels, as well as between
the substances that are found to be contained

* De l’Influence des Agens, &c. ch. xii. p. 345
et seq.

t De V’Infiuence, &c. ch. xiii. p. 556 et seq.
See on this subject, Magendie,'Physiol. t. ii. p. 189. .
196, and Dict. de Méd. et Chir. Prat. « Absorp-
tion ;” where he endeavours to prove, that it is the
veins and not the lymphatics which are the agents
in cutaneous absorption. See also the remarks of
M. Rullier, ch. ii.; and of M. Adelon, Physiol.
t. iii, p. 10 et seq.; also art. ‘ Absorption,”
Dict. de Méd. t. i. p. 124 et seq. M. Chaussier
found that sulphuretted hydrogen gas, when ap-
plied to the surface of the body, manifested its
deleterious effects on the system, Bibl. Méd. t. i.
We have already had occasion to notice the opinion
of Walter on this subject, p. 25, which is similar
to that of M. Magendie. M. Buisson attempts to
establish a distinction between the absorption which
is carried on by the membranes and by the cellular
texture, De la Divis. des Physiol. Phenom, p. 251
et seq.

${ M. Magendie indeed doubts this position so
far as the ag are concerned ; Journ. Phy-
siol. t.i. p. 18 et seq. and Physiol. t. ii. p. 238..

ABSORPTION.

in them, that we are naturally led to conclude,

that they are destined for different uses, and
serve different purposes in the animal economy.

With rd to the lacteals, their use seems

to be clearly marked by their connexion with

the digestive organs, and by their contents,

as constituting the channel by which the chyle

is conveyed from the intestines to the thoracic

duct, and ultimately to the bloodvessels. We
cannot doubt that their primary function is to

| supply the body with the elements which com-
; obs the blood, and thus become the imme-
iate agents in its nutrition. Although, from

the experiments which have been related
above, it will appear that, on certain occasions,
the lacteals are not incapable of receiving
extraneous bodies, yet we may conclude, that
this is the case only under extraordinary cir-
' cumstances, or in an unnatural state of the

ODA 5 TE SRD SER AP RST OT

With respect to the lymphatics, their specific
; use is less obvious. As their contents are ul-
___ timately mixed with those of the lacteals, we
‘may suppose that they contribute indirectly to
the nutrition of the body; but this would
appear not to be their primary, or even their
principal destination. Still we can scarcely
refuse our assent to the position, that absorp-
tion is the specific function of the lymphatics ;
and this will be equally the case, although we
may suppose that the veins cooperate with them
in this action.

We are indebted to the genius of John Hun-
ter for a consistent or plausible theory of the
use of the lymphatics, which, with certain mo-
difications, is generally admitted to be correct.
Conceiving that the appropriate and specific
action of the lacteals is to nourish the body,
and to support the system by the addition of

new matter, that of the lymphatics is to mould
_ and fashion the body, to admit of the growth
and extension of the whole, while each in-
dividual part retains its proper form and
_ position. When we consider in what manner
' an organized part increases in its dimensions,
| we immediately perceive that it is not by mere
accretion, nor by simple distention; it is, on
_ the contrary, by an addition to every individual
_ portion, while they retain the same relation to
each other and to the whole. If we take the
ease of a muscle, we find that each particular
fibre must be increased in length, so that the
‘distance may be augmented between the ten-
dinous extremities, while probably the number
of fibres that are contained in the membranous
‘covering is also increased; the whole organ
consequently becomes larger in every one of its
‘individual parts, while they each retain their
f proportions and connexions.*
_ We may apply the same train of reasoning
to the bones, which offer a still more remark-
able example of this change of form, inas-

*.
-

eee ee ee Ee ee eee

‘diem el

ee ee ee BFL AR ee aR Aah ew

tidemcend

te

Torme

___—-—sSC** *‘See Winterbottom, de Vas. Absorb. in Smel-
____ hie’s Thes. Med. t.iv.; also Cruikshank, p. 108, 9.
_ For the more recent views of physiologists on the
Subject the reader is referred to Adelon, art.
_ Absorption,” Dict. des Scien. Méd. t. i.

VOL. I.

33

much as the firmness of their texture must
render it less easy to conceive of any alteration
in their dimensions and in the disposition of —
their component parts. Here it is still more
obvious than in the case of the muscle, that
the change cannot be effected either by accre-
tion or by distention, but that a completely
new disposition of the integrant parts must
have taken place. The only means, however,
by which this can be accomplished is by the
former particles of the body being gradually
removed, and new ones deposited to supply
their place ; the process being so gradual, that,
although the deposition of the new particle is
not precisely in the same situation with the
former, yet that of each particle is so nearly
so as to cause no obstruction or interruption
to the action of the organ. Now it is evident
that this removal of the old matter can be
effected by no process but by absorption, and
we may therefore conclude that the lymphatics,
either alone or in conjunction with the veins,
are the agents destined to perform this office.

With respect to the actual nature of the con-
tents of the lymphatics there appears to be
some uncertainty. We have the analysis of
the fluid taken from the vessels of a dog by
M. Chevreul,* from which it would appear
that the lymph contains nearly the same in-
gredients with the blood, but diluted with a
much larger proportion of water. We must,
however, suppose that the fluid contained in
the lymphatics will vary very considerably in
its composition, according to the part of the
body from which it is taken, or the condition
of the same part at different times; yet we are
scarcely able to detect an actual state of things
which altogether corresponds with what we
might have been led to expect would have been
the case.t It may indeed be presumed that
in the ordinary condition of the system, the
process by which the parts of the body are
absorbed is so very gradual, that the change in
the chemical constitution of the lymphatic
fluid is as inconspicuous as the change in the
organs from which it is absorbed, and that it
is only in morbid cases, where there is some
extraordinary quantity of matter to be re-
moved, that we should expect to be able to
detect it inthe lymph. And this, to a certain
extent, agrees with the fact; for when the ab-
sorbents are called into action to remove col-
lections of pus, or when they become the
vehicles of any poisonous or morbid body,
the substance in question has been occasionally
found in them.

The doctrine of the removal or absorption of
all the parts of the body is rendered evident by
a variety of cases, in which any particular
organ or texture is broken down or removed,
merely by cutting off the supply of fresh matter.
It is upon this principle that we explain the

* Magendie, Elem. t. ii. p. 171, 2. id

+ Magendie, Elem. t. ii. p. 196, 7, et alibi.

Mascagni, however, states that the lymph varies

according to the parts to which it is contiguous,
ps. 1. §. 4.3 see also Blumenbach, §. 438.
D

34°

removal of a part by pressure. Ifa muscle, or
even a solid bone be exposed to constant pres-
sure, by which its nutritive arteries are ob-
structed, it will be gradually diminished in
bulk, and at length completely abstracted.
And this is frequently effected by the action of
a body much softer than the substance which
is removed, as, for instance, we observe a bone
to be absorbed by the pulsation of a blood-
vessel, or the growth of a fleshy tumour.*

But although we may venture to affirm that
this moulding of the body, or rather of its in-
dividual parts, is effected by the lymphatics,
either alone or in conjunction with the veins,
there is considerable difficulty in forming a
distinct conception of the mode in which they
operate. ‘The operation cannot, strictly speak-
ing, be mechanical, nor have we any evidence
of the existence of a chemical solvent, by
which the parts may be reduced to a liquid
state, so as to fit them for entering into the
mouths of the vessels. We may conceive of
the source of supply being cut off by pressure
or in other ways, but still we are ata loss to
account for the mode in which the solids are
either dissolved or broken down, so as to adapt
them to the process of absorption. There is,
however, one principal or general fact in the
animal economy, which will probably some-
what assist us in our inquiry, viz. that it appears
to be essential to the well-being, or even to the
existence of the corporeal frame, that all the
materials of which it is composed should un-
dergo a constant change. Itappears that these
materials, after a certain length of time, expe-
rience some alteration in their nature, by which
they are rendered unfit for the further perform-
ance of their functions as constituents of the
living body. They are therefore removed and
are replaced by fresh matter, this interchange
being brought about in the gradual manner
which was described above. Now this process
implies a constant decomposition of the parts
of the body, and as this decomposition is
effected particle by particle, it may not be un-
reasonable to conjecture, that each particle,
when it ceases to form an integral part of an
organ, is left in a state proper for being taken
up by the absorbents. But independent of any
hypothetical views of this description, we may
assume it as a probable conclusion, that the
configuration and moulding of the body is the
specific and appropriate office of the lymphatics,
while its nutrition is effected more immediately
by the lacteals.

With respect to the lymphatic glands we
have seen above that their structure is involved
in considerable obscurity, and we may remark,
that their use is at least equally obscure. Among
other opinions that have been entertained on

* For the absorption of the solids, see Monro on
the Brain, c. 5; also Blumenbach, §. 436; and
Bell’s Anat. vol. iv. p. 311,2. Ribes, who is a
zealous defender of the doctrine of venous absorp-
tion, remarks that the absorption of the bones must
be effected by the veins, because they are not fur-
nished with lymphatics; Mém. Soc, d’Emulation,
t. viii. p. 621. ;

ABSORPTION.

the subject, some physiologists have sup;
that the glands are proper secreting nS,
which are destined for the purpose of ade +
a peculiar substance that is mixed with the
chyle and the lymph, or that they merely serve
the mechanical purpose of mixing together more |
completely the constituents of the fluid that is
contained in the vessels, and thus produce
some change in its nature or. consistence.*
There do not appear to be any arguments, either
anatomical or physiological, by which this point
can be decided; but we may remark, that
while the number and mode of distribution of
these glands in the mammalia would seem to
point them out as performing some important
office in the animal economy, their rarity in
birds and fishes proves that they are not essen-
tial to the existence of most of the functions of
animal life, nor have we any mode of explaining
the cause why they should be more necessary
to the mammalia than to the other classes,
which in many of their functions so nearly re-
semble them.

Tt only remains for us to offer a few remarks
on the connexion between the function of ab-
sorption, and the other vital actions of the
system, especially with the two leading princi-
ples of contractility and sensibility. Wehave —
already had occasion to remark on the con-
nexion of absorption with muscular contracti-
lity, and although it may be difficult, or even
impossible, to demonstrate the muscular fibres,
or to exhibit any apparatus of this description,
by which the action of the vessels can be ac-
counted for, still we have strong reason for
supposing that the absorbents possess this :

.
i

power, and that it is the main cause by which
their contents are propelled.

With respect to the relation which subsists
between the nervous and the absorbent systems,
we are induced. to suppose, both from anato-
mical and from physiological considerations,
that it is merely of an indirect nature. From
the researches of the anatomists, we learn that
there are few nerves sent to the absorbent vessels
or glands, and that even these seem rather to
pass by them, in order to be transmitted to
some other organs, than to be ultimately des-
tined for the use of the absorbent system. The
action of the mouths of the lacteals, or the
power by which they are enabled to take up
the substances that are afterwards transmitted
along them, is involved in much obscurity, as
is likewise the case with the power which these
vessels seem to possess of changing the nature
of their contents. Both of these have been re- —
ferred to the nervous influence, but this has
been done in that loose and general way, which

* On this subject we may refer to Haller, El.
Phys. ii. 3.25; Blumenbach, Inst. Phys. §. 425,
442; Richerand, Elem. p. 153; Mascagni, ps. i.
sect. 5. p.33; Magendie, Elem. t. ii. p. 166, 201
Chaussier et Adelon, ubi supra, p. 278. Rull
art. “ Inhalation,” in Dict. Sc. Méd.; Me
Manuel, sect. 6. ch. i. ; Adelon, art. ‘* Lymphatique
(Physiologie),” Dict. de Méd. t. xiii, also art.
“* Chyliféres,” ibid. t. v. p. 239; Desgenettes,
Journ. Méd, t. xc. p. 322, et seq. ee

ACALEPH&.

is too frequently met with in the reasoning of
physiologists. We do not perceive, in either
case, how it can be referred to this power, nor
how it can be employed: in any way to explain
or elucidate the effects that are produced.*

It is admitted that the chyle is elaborated
during its passage along the lacteals, and be-
comes more nearly assimilated, both in its phy-
sical and chemical properties, to the blood.
Still, however, its complete sanguification does
not take place until it leaves the lacteals, and
it becomes a very interesting subject of inquiry,
by what means this is effected; in what degree
the function of respiration contributes to it,
_ whether the abstraction of carbone and the in-
troduction of oxygene, which is supposed to be

_ effected by the passage of the blood through |

the lungs, is the immediate cause of the con-
- version of chyle into blood; whether it be
_ brought about more gradually, by the removal
of the various secretions and excretions, or
whether there be any particular organ, which
May more especially produce the change in
_ question. ‘These are all of them points of high
_ interest, but as they are concerned in an indi-
_ rect manner only with the subject of this article,
_ and as they will be considered in the appro-
priate parts of this work, we shall not pursue
_ the inquiry any further.

___ BIBLIOGRAPHY. — Abernethy, in Phil. Trans.
1776 and 1796. Adelon, in Dict. Scien. Méd.
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per.

are f
Orptio!
74

=

“ae

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945; and Gordon’s Anat. p. 71.

35°

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Trans. 1769. Werner, Vas. Lact. et Lymph. Desc,
Winterbottom, De Vas. Abs. in Smellie, t. iv.
Wrisberg, Observ. Anat. Vas. Abs., in Com. Gott.
t. ix. Young’s Medical] Literature.

(J. Bostock. )

ACALEPH (from axaangn, a nettle); syn.
urtice marine. Fr. Acaléphes; Germ. Acalephen ;
the name of a class of invertebrate animals.
They areall inhabitants of the sea, and are such
as are commonly known by the names of sea-
jelly, sea-nettle, Portuguese man-of-war, &c.
It is from the property, which many of these
animals possess, of irritating the surface of our
skin so as to produce nearly the same effect
as that resulting from the sting of a common
nettle, that the class derives its name.

Aristotle used the word axaaAngy to de-
signate some of these animals; but it was by
Cuvier that the class was formed, and the
term acalephe applied to it. As this class now
stands in the last edition of the Régne Ani-
mal, (t. iii. p. 274,) it is formed chiefly by
the animals constituting the Linnean genus
Medusa and les acaléphes hydrostatiques of
Cuvier.

On many accounts the acalephe are objects
of extreme interest to the anatomist and phy-
siologist. They have occupied the attention
of the most learned naturalists of every age,
from the time of Pliny until the present day ;
their numbers are, perhaps, greater igs those

D

i

_ of any other class of marine animals: they exist
in all seas; and yet we remain very ignorant
with regard to several points in their structure
and history. The peculiar nature of their
tissues, the singular arrangementsof their organs,
the anomalies im their functions, present as many
objects of interesting inquiry to the physiologist,
as the wonderful variety and striking elegance
of their forms, and their splendid colouring

resent to the admiration of the naturalist.

eron,* in his animated description of the Me-
duse, observes, “Among the animals of this
family we find the most important functions of
life performed in bodies which offer to the eye
little more than a mass of jelly. They grow fre-
quently to alargesize, soasto measureseveral feet
in diameter ; and yetwe cannotalways determine
what are their organs of nutrition. They move
with rapidity, and continue their motions for
a long time ; and yet we cannot always satis-
factorily demonstrate their muscular system.
Their secretions are frequently very abundant,
and yet the secreting organs remain to be dis-
covered. They seem to be too weak to seize any
vigorous animal, and yet fishes are sometimes
their prey. Their delicate stomachs appear to be
wholly incapable of acting upon such food,
and yet it is digested within a very short time.
Most of them shine at night with great bril-
liancy, and yet we know little or nothing of
the nature of the agent which produces so re-
markable an effect, or of the organs by which
it is elaborated. And, lastly, many of them
sting the hand which touches them; but how,
or by what means, they do so still remains a
mystery.” It is, therefore, but a very imperfect
account of the anatomy and physiology of this
class that can be at present given.

The following are the names and characters
of the groups into which the acalephe have
been divided by M. De Blainville,t whose
arrangement is nearly the same as that adopted
by Eschscholtz. t

I. Puysocrapa. Body regular, symme-
trical, bilateral, fleshy, contractile, often very
long, provided with an aeriferous sac. Bran-
chiz in the form of long cirri, very con-
tractile.

1. Organ of natation simple and lamellated.
Gen. Physalus. ( Physalia, Lam.) .

2. Locomotive organs complex and vesicular.
Gen. Physsophora. Diphysa. Rhizophysa.

3. Locomotive organs in the form of smooth
scales, disposed in transverse series. Gen.
Stephanomia. Agalma. Protomedea. Rho-
dophysa.

I. Dipuypa. Body bilateral and symme-
trical, composed of a visceral mass of small
size and of two swimming organs, hollow,

* Peron. Ann. du Mus. xiv. 220.

+ Dict. des Sc. Nat. “* Zoophytes.” 1830.

$ System der Acalephen. Berlin, 1829. The
most complete treatise on the anatomy and history
of the acalepha hitherto published. Its learned
author enjoyed excellent opportunities of studying
these animals in the course of the two voyages
round the world undertaken by Kotzebue, of whose
expeditions he was naturalist.

F
ACALEPH. -

contractile, somewhat cartilaginous, and placed
one before the other, the anterior one being
in more direct connexion with the central —
visceral mass, which it seems to surround;
the other posterior, and very slightly adherent. —
Mouth at the extremity of a stomach more
or less extensile. Anus unknown. A long
filamentary organ, ovigerous, rises from the
root of the central mass, and is prolonged —
more or less posteriorly. is

Gen. Cucubalus. Cucullus. Cymba. Cu-
boides. | Enneagona. Amphiroa. Cl
Abyla. Diphyes. Ersaea. Eudoxia. Py-
ramis. Praia. Tetragona. Sulculeolaria.
Galeolaria. Rosacea. Noctiluca. Doliolum. ;

III. Citrocrapa. (Ctenophore, Esch.) —
Body gelatinous, free, varying in form, marked
on the surface with narrow ambulacra formed 4
by rows of vibratile cilia. Intestinal canal —
complete, with two orifices.*

Gen. Beroé. Eucharis. Mnenia. Cal-
ymma. Axiotoma. Callianira. Pandora.
Medea. Alcynoé. Cestum. Cydippe. Idya.

IV. Putmocrapa. (Discophore, Esch.)
Body entirely gelatinous, circular, without
any solid part internally, margin provided
with cirri of various forms, or with foliace-
ous appendages pendent from the inferior
surface.

1. Simple: without true tentacula, peduncles
or arms.

Gen. Eudora. Ephyra. Phoreynia. Eu-
lymene. Carybdea. Euryale.

2. Tentaculated: the circumference of the
body, and sometimes the mouth, surrounded
by tentacula.

OE a a

Gen. Berenice. Equorea. Foveolia. Pe- ~
gasia. Cunina. gina. Eurybdia. Thau- —
mantias. QObelia. Linuche. Eirene.

3. Subproboscic: gastric cavity prolonged
into a short peduncle, at the extremity of which
is the mouth, surrounded by four brachial
appendages.

Gen. Oceania.
phenia. Tima.

4. Proboscic: the lower and central part —
of the body prolonged into a proboscis-like
appendage, either simple or provided with —
arms. |

Gen. Orythia. Fa- |
vonia. Cyteis. 4

5. Brachigerous: lower surface furnished
with more or less numerous appendages, bra-
chial, ramified. © ;

Gen. Ocyroé. Cassiopea. Medusa (Au-
relia of Peron), Callirhoé. Melitea. ya=
gora. Cephea. Rhizostoma. Chrysaor.
Cyanea. Pelagia. Sthenonia.

V. Crrricrapa. ( Velellide,

Aglaura. Melicerta. Sa-

Geryonia. Diancea.

_ ™ M. De Blainville regards the animals include
in this and the two preceding sections as bei
more allied in structure to the Mollusca, (his Ma

cozoaires, ) than to the Radiata, with which th by

arranged by most zoologists. Accordingly he sep
rates them from the two succeeding sections, whi
are truly radiate animals, and of which he forn
a class in his great division Actinoxoaires, under th
name of Arachnoderma. i *

ACALEPH.

Body oval or circular, gelatinous, et tee by
an internal, solid, subcartilaginous y, and
provided with very extensile tentacule-like

= te pendent from the whole of the lower sur-

Gen. Velella. Porpita. Rataria.*

Of the genera above enumerated, Eschscholtz
has described about two hundred species.
Messrs. Quoy and Gaimard have made us ac:
quainted with several others; but of all these
a comparatively small number only have been
ascribed: in detail: so that, although in the

account which we are now to- give of the

anatomy and physiology of the acalephe, we
shall, for the sake of brevity, make use of the
‘sectional designations, it must be understood

_ that the descriptions apply only to a few

‘species, and that, with regard to the others

grouped along with these, we can only say

it is probable that they are similarly con-

__ I. Locomotion. The principal organ of
locomotion in the physograda is the air-filled
_ vesicle or bladder, which exists, of various
sizes, in all the species. In physalus, ( Fig. 6.)
_ it is a large organ, forming a great portion of
_ the general mass of the animal. It is placed

_ * The following neat but artificial arrangement
of he forms the subject of a communication
_ lately made to the Zoological Society by M. Lesson,
_ foreign member of that body: we are indebted for it
to our friend Mr. Owen.

I, Without a central solid axis.

_ A. Body simple, entire.

1. Symmetrical, termi-
nated at each pole by
anopening . - . .1 Beroida.

2. Non-symmetrical, the
upper pole disciform or
umbelliform, imper-
forate. . . . . .2 Medusa.

B. Body multiple or aggre-
gated.
a. Homogeneous.

3. Composed of two pieces
adhering together, and
capable of separation .

4. Composed of numerous
pieces aggregated toge-

- SOB: Le delueiye © oo
« 6. Heterogeneous.
os «em eee with
appendages of different
dads.
_ * Vesicle small, regular,

n _ placed at the summit of
a kind of stalk fur-

3 Diphydes.

4 Polytoma.

nished with lateral am-
_ a pulle, and terminal
a suckers ee eee oe
_ ** Vesicle large, irregular,
without stalk or am-
pulle, but having ter-

minal suckers and cir-

ae: rocesses . . 6 Physalia.
I With a central cartilaginous

+ axis,
6. Body simple,
suckers and i;
tacula

__ @ +=Body irregularly oblong,
“a with a vertical lamina
on its upper surface . 7 Velelle.
b. Body discoid, flat above. 8 Porpite.
R. B. T.

5 Physsophore.

with
ateral ten-

37

superiorly, and, for the most part, rises above
the surface of the water. It has an elongated
form; the longest diameter being the hori-
zontal. It is somewhat pointed at one end,
at the other truncated ; and at either there is
a small opening, the place of which is marked
by a superficial dimple, surrounded by delicate
muscular fibres, acting as sphincters. When

(Fig. 6.)

Physalus Utriculus, (Esch.)

the bladder is squeezed by the hand, so as to
force the contained air towards one of these
openings, the air makes its escape through it;
but whenever the pressure is taken off, the
Opening again closes. M. De Blainville states
that he has satisfied himself that this air-blad-
der is really a dilatation of the intestinal canal;
and that he regards the two openings mentioned
above as the mouth and the anus. We are
ignorant of the data upon which M. De Blain-
ville grounds his conclusion. It does not ap-
pear that any observer has found alimentary
matter lodged within the air-sac. But whether
or not it be an organ of digestion, it is cer-
tainly an organ of locomotion, although only
a passive one; for it is by its contained air that
the animal floats on the surface of the water,
so as to expose a large superficies of its crest
and bladder to the wind, by which it is driven
to and fro frequently with great velocity. The
walls of this sac are muscular, so that by their
contraction its cavity can be considerably dimi-
nished. And thus, partly by the escape of air
forced out through the openings, and partly by
the compression of what remains, the specific
gravity is so much altered as to admit of the

38

animal’s sinking into the deep when danger
threatens. In the other physograda, the air-ve-

: | sicle is so small in pro-
portion to the general
-Inass of the animal that
it is not sufficient to
raise it above the sur-
face of the water. It
is generally an ovate
sac, with an opening
at its upper end, closed
by a sphincter muscle.
It is probable that its
walls are muscular, and
that by pressing out a
portion of the contained
air, and by secreting
more, alternately the
animal can sink and
rise at pleasure. The
nature of the air con-
tained in these vesicles
has not yet been ascer-

|
Rhizophysa Melon.

tained. In rhizophysa
( Fig.7.) there are, pen-
dent from one part of the
body, certain peculiar

.ACALEPHE.

of their being sepa
water. mee 4
vity that the essential parts of the animal —

the organs above described. The contractions —

ings. Their attachment is so slight as toadmit E
by agitation of the —

It is at the bottom of the a

are placed. Locomotion is effected by means —
of the impulse of a current which is kept up —
by the successive contractions and dilatations of —

of the two bodies are not synchronous; but —
they succeed one another within a short time, —
so that a steady progression is maintained; —
and in some species it is very rapid. i.

In the ciliograda, the locomotive organs are _
large cilia, disposed in longitudinal bands on _
the surface of the body. These bands are ge-
nerally eight in number; but in some species,
(e.g. axiotoma Gaedii, Esch ,) there are only —
four. The arches supporting the cilia are of
firmer texture, and are less transparent than
the rest of the body. In many species they —

extend from one end of the body to the other;

in some only along a part of the circumference.

The structure of the cilia themselves has lately
Fig. 9.

a

organs, arranged very re-
gularly in pairs, ofa mus-
cular structure, hollow,
and furnished each with
a round orifice. They
differ from the tentacula
in structure, and are, pro-
bably, organs of natation. )

Similar tubes, but only

two innumber, exist in diphysa ; and, anterior

. to them, in the same animal,

Fu 8: there is a two-lobed organ,

i ay an the use of which is doubt-
wee ful. In agalma, (fig. 8.) and
as Tose some of the genera allied to
b> it, there are certain cartila-
oe ginous plates disposed in an
eed imbricated manner along the
tp sides of the body. These,

Eschscholtz regards as loco-
motive organs. The mus-
cles by which they are set in
motion must be extremely
delicate, as a slight touch is
sufficient to separate the
. plates from one another.
y The chief bulk of the sin-
gularly formed diphyda is
made up of the swimming
organs, which are two sub-
cartilaginous bodies, poly-
gonal, generally pointed an-
teriorly, truncated posteri-
orly, placed one behind the
other, and one a little within
AA the other; the posterior por-
tion being lodged in a little
excavation which exists in

Wx

J

«,

oF 42 ae «: the anterior. These two parts
A differ somewhat from one

bh. A\ another in form,-but both are —
hollow, and have large open-

Agalma okenit.

of the skin along the cilia-bearing arches, which

ae

Diphyes Campanulifera.

been examined by Dr. Grant,* with his usual
care, in the Beroé pileus;+ and he has found
that they are fin-like processes, and that each ~
is composed of several short, transparent, some- —
what curved filaments, placed parallel to each
other in a single row, and connected together
by the skin of the animal, like the rays sup- ~
porting the fin of a fish. The rays in the ©
middle of the cilium are a little longer than
those at the sides. -All the rays appear as ©
transparent tubes under high magnifying pow- —
ers. They are so curved that their extremities
are directed backwards towards the closed ex-
tremity of the animal. There are about forty
cilia attached to each arch in this species, which
is nearly an inch in length, The cilia are so
large as to be visible to the naked eye. Most
of the ciliograda have their cilia quite exposed;
but Pandora is provided with moveable folds’

can be brought over the cilia, in whole or in
part, at the animal’s pleasure, so as to cover
them more or less completely. These cilia are
moved nearly in the same manner as the pec-
toral fins of fishes. But their motion is so
rapid, when the animal is vigorous, tl
eye cannot follow it. . The existence of r
is pointed out, however, by lines of beautifu

iridiscent colours playing along the arches, am

* Trans. Zool. Soc. of London, i. 10. ,
+ Pleurobrachia pileus. Fleming. Brit. Anin
504, Cydippe p. Esch. P

ACALEPHE.

by the currents which are generated in the cir-
cumambient fluid. The animal has the power
of arresting completely the motion of one, two,
or more rows of cilia, while the others are
moving. When all are set in motion together,
the animal moves onwards with the inferior or
oral surface (inferior in a state of rest) directed
forwards. When the motion of some is ar-
rested, the whole body acquires a rotatory mo-
tion, and advances in a curvilinear path. The
animal has also the power of changing the
direction of the currents caused by its cilia, so
that it can ascend or descend in the water at
pleasure. It can also increase and diminish at
' will the velocity of the motions of the cilia.
Those animals which have the largest cilia, (e. g.
Medea,) swim with the greatest rapidity. The
cilia continue to move for some time after
having been separated from the body, in con-
nexion with part of their arches. Immediately
_ beneath the arches there are vessels conveying
} a fluid, which is in motion during the vibrations
“ of the cilia. Whether these vessels are destined
_ only for the conveyance of the circulating fluid
to the ciha, (which in all probability act as
organs of respiration as well as of locomotion,)
or carry a stimulus fitted to excite their vibra-
tions, is not yet determined. Eschscholtz com-
! these vessels to those which Tiedemann
as described as connected with the feet in the
echinodermata. And Dr. Grant is of opinion,
with MM. Audouin and Milne Edwards,
that it is not improbable that the motions of the
cilia are somehow dependent on the movements
of the fluids contained in the above-mentioned
vessels, seeing that in the actinie the tentacula
are projected by water being forced from below
_ into them. In the other classes of the acalephe
_ also the same kind of structure prevails. Such
_ of the pulmograda as have cilia around their
__ Margins have also circular vessels running along
_ their bases; and almostall projectile and exten-
_ Sile tentacules and filaments are provided with
_ Sacs and canals, containing fluids, at their roots.
____ In addition to their cilia, several of the cilio-
_ grade acalephe have other organs of locomo-
tion in the form of long filamentary arms or ten-
- tacules, with which they can poise themselves
“in the water without moving their cilia. In Cy-
They are
odged in two tubes placed alongside of the sto-
tach, from which they issue near the mouth.
They can be extended to four times the length
of the animal. They terminate in very fine
_ points, and along their whole course present
minute filaments placed at equal distances,
ich are coiled up spirally, close to the ten-
ules, when these are about to be withdrawn
into their sheaths. The tentacules are also
coiled up in a spiral form when completely
contracted. They are sometimes suddenly sent
_ forth from their tubes to their full length by
one impulse, and then their lateral filaments
rope jpadontts uncoiled ; a process this of no less
interest on account of the gracefulness of the
‘motion than on account of the peculiar mecha-
nism which it indicates.

dip # these are two in number.

‘
i]

a
7
}
-
b
Ft

* Grant. Trans. Zool. Soc. i. 10.

218,

39

The principal organ of motion.in the pulmo-
grada is the large campanulate, or mushroom-
shaped, disc, of gelatinous consistence, which
constitutes the great mass of the animal. In
this, for the most part, no muscular fibres can
be seen, and yet the animals move about with
some quickness. They have the power of con-
tracting and dilating their discs at pleasure, in
whole or in part. By alternately contracting
and dilating their inferior surface, they strike
the water in such a manner and with such force
as to raise themselves; when they discontinue
this motion, they again sink, being of greater
specific gravity than the sea-water. They move
onwards horizontally, by acting only with one
side of the margin of their disc. Lamarck
was of opinion that these isochronous move-
ments of the disc, by means of which the pul-
mograda seem to swim, were fitted merely to
facilitate the internal vital processes, and not
to move the animals through the water; and
he regarded them as dependent entirely on the
influence of imponderable agents existing in
the circumambient fluid, and alternately enter-
ing into, and flowing from, the general mass of
the animal. He compared the motions with
those of the fluid in Franklin’s thermoscope,
when held in the hand.* In the course of the
ordinary progression of the large Medusa aurita
of our seas, the contractions of the dise take
place from twelve to fifteen times in a minute.
The convex surface of the disc always advances
foremost.

No fibrous structure has hitherto been dis-
covered in the general mass of the disc. In-
ternally, it is cellular, uniform, and very soft.
The quantity of solid matter in the disc, and,
indeed, in the whole body, is very small.
Some medus@, which, when recently taken out
of the water, weighed fifty ounces, on being
dried, left remains weighing scarcely more than
five or six grains. “ It is therefore evident,
that the sea-water, penetrating the organic tex-
ture, constitutes the greater part of the volume
of these animals.”’+ But in some species there
exists a fine muscular membrane, stretched
over a certain extent of the lower surface just
within its outer margin. Under a lens, this
has the appearance of being composed of nu-
merous fleshy fibres, forming little bundles,
arranged in a radiate manner as regards the
axis of the animal, and closely adherent to the
gelatinous tissue of the disc. When portions
of the dise are cut off from living meduse,
without any part of this muscular membrane
being attached to them, they remain motionless;
but when their connexion with the membrane
is preserved, even small portions continue their
motions of contraction and dilatation for a
considerable time.

The tentacula of the pulmograda (which are
always pendent from the inferior surface) may
be regarded as supplementary organs of loco-
motion, although they are, in all probability,
subservient chiefly to the nutritive function.
They are all simple, not branched, generally

* Anim. sans Vert. ii. 454.
+ Spallanzani, Travels in the Two Sicilies, iv

40

hollow; and, when connected with the appen-
dages of the digestive cavities, or when they have
a vesicle at their base, very extensile. Several
genera have suckers at the extremities, and
along the sides, of their tentacula, by means of
which the passing prey is seized. The tenta-
cula which are extensile seem to be projected
by the forcing of water into their internal cavity,
by the contractions of the vesicles at their base.
The extent to which the filamentary organ is
thus lengthened, in some species, is very extra-
ordinary.* It seems to be shortened again by
means of the contractions of circular muscles,
which force back the water into the vesicle, and
of longitudinal muscles which draw it in.
Peron thought that some of the pulmograda
were furnished with internal air-bladders; but
Eschscholtz, on directing his attention to this
point, satisfied himself that what Peron had
taken for air-bladders were merely appendages
of the gastric cavities, into which air had acci-
dentally been introduced during the removal
of the animals from their native element.

In the cirrigrada, locomotion is effected

Fig. 11.

Velella septentrionalis.

* In the tentacula of some of the physograda,
also, a similar extensibility exists. The lower sur-
face of physalus, for instance, which itself seldom
exceeds six inches in length, is provided with ten-
tacula sixteen and even eighteen feet long.

ACALEPHE.

- which hang down from the inferior surface

partly by the movements of the tentacules

but chiefly, perhaps, by the action of the wind

on the raised crest, with which most of these
animals are provided. Immediately around

the mouth are placed numerous small tubular

suckers, similar to the feet of many echinoder-
mata. Exterior to these there are longer tenta-

cula, for the most part in a single row, and

simple; sometimes branched. Neither of these

two kinds of organs is very extensile. The

disc from which the tentacules hang, and the

crest, are supported internally by a calcareous

plate, which is the only organ of the kind in

the whole class of acalephe. It somewhat re-

sembles in structure the calcareous axis of
retepora, being cellular and porous. Its nu--
merous cells are filled with air, which renders

the whole animal so buoyant that it floats on the

surface of the water, and is wafted along by the

winds. In velella ( Fig. 11.) there are two

plates, one placed horizontally, the other perpen-

dicularly upon the upper surface of the former.

They are marked with lines of growth, enlarg-

ing from within outwards, like the extravascular

shells of the mollusca. The perpendicular

plate in velella supports the crest, which stands

upright, and exposes a large surface to the wind.

Rataria ( Fig. 12.) has its crest provided with

strong muscular bands run-
ning perpendicularly. It
lies on the surface of the
water, with the crest stretch-
ed out, so that its whole side
touches the water. When
it is alarmed, the crest is
suddenly contracted, and the
centre of gravity is so al- fit

tered in sbuaqueness that Rataria cordata.
the position of the body is almost reversed.
When the crest is again raised, the body imme-
diately resumes its former position.

Porpita has a simple plate supporting its dise,
without any crest, and long tentacula, which are
so delicate as scarcely to bear the slightest touch
when the animal is taken out of the water. When
the position of the animal is altered by the hand,
so as to make the surface covered with suckers
the upper one, all the tentacula of one half of
the body turn round to the dorsal surface, and
all those of the other half stretch over their
own surface, and thus the animal very soon
regains its old position.

II. Motility and Sensation. — Almost all —
observers have failed to discover anything re-
sembling a nervous system in the Acalephe.
Even Eschscholtz,* who devoted so much atten- —
tion to their anatomy, could not see nerves in
the largest that he examined. But in Cydippe,
according to Dr. Grant,+ there is a structure —
which can be regarded only as belonging to
the nervous system. It consists of a double
transverse filament of a milky white colour,
running round the body, near its surface, at a
short distance above the mouth. The t
cords of which this filament is com te
in the middle of each of the spaces betwee:

Fig. 12.

* System, p. 19.
T Trans. Zool. Soc. of Lond. ,- 10.

Fhe eh SARA mete

i ] e aA ite ji LAGASSE OD Cia ESATO WR GOI FRET RA! RS a
Sah Me RFR, SR ee lek ad Mine A lbh SE en sabe dn HA r a

round the circumference of the disc.

ACALEPHEE. 41

the ciliated arches to form eight ganglia, from
each of which two nerves go to the adjoining
bands, and one, larger than the others, runs
upwards in the middle of the transparent space
between the bands, and can be traced to be-
yond the middle of the body. In the course
of these last-mentioned nerves, two or three
smaller ganglia are visible, from which fila-
ments pass inwards to the viscera. Dr. Grant
likens these nerves and filaments to the abdo-
minal nerves of pectinaria and other transpa-
rent animals.

The circular fibres forming the sphincters of
the orifices of the air-bladder in physalus have
been mistaken for nerves.*

There is no evidence that the acalephz possess

- any other sense than that of touch. But, al-

though they cannot be said to have the sense of
sight, they are evidently affected by light. At
least some of the smaller tribes shun a bright
light, and sink into the deep to escape from it.
In most of the tribes of acalephe, the sense
of touch seems to have its seat chiefly in the
tentacula and cirri, with which almost all are
provided. The degree of sensitiveness with
which these are endowed varies much. In

_ some, the slightest touch, even agitation of the

water, is sufficient to excite them to contrac-
tion. These organs of touch, as has been al-
ready mentioned, are subservient chiefly to the
nutritive functions. Other parts of the bodies
of most acalephe also manifest, by their con-
tractions, a certain d of sensitiveness.
Several of the ciliograda alter the shape of
their general mass when touched. In physalus
the crest appears to be more sensitive than any
other part. Many species, particularly of the
pulmograda, give no signs of their feeling even
the deepest and most extensive wounds of their
discs. But it was observed by Spallanzani,
that, by friction, and by punctures of the mus-
cular membrane of the disc, the movements of
contraction and dilatation could be excited in
meduse, which, having been kept in a dry

- place during twenty-four hours, had discon-

tinued their ordinary motions, and had lost
nearly two-thirds of their bulk by the running
out of their contained fluids.t

* Isis. Nov. 1819.

t Professor Ehrenberg has very recently attempted
to shew that medusa aurita is possessed of eyes, in
the form of minute red points, which are seen on
the surface of the eight brown-coloured masses set
These masses,
according to his observations, consist each of a yel-
lowish, oval, or cylindrical little body, which is at-
tached to a small and delicate pedicle. This short
pedicle arises from a vesicle, in which there is

a glandular body, unattached, presenting a
Tighe. colour when viewed with transmitted
light, a white colour under reflected light. It
is meee the dorsal aspect of the yellow head,
which surmounts the pedicle, that the well defined
red point is seen, which Ehrenberg considers as an
eye. He compares the eyes of medusa to those of
some rotifera and entomostraca. The glandular body
Situated at the base of the pedicle, he regards as an
Optic ganglion, which, he seems to have satisfied
himself, is connected with two filaments that decus-
sate one another at about the middle of their course.
These he describes as forming part of a nervous

III. Digestion—The structure and action
of the organs concerned in the function of
digestion in the acalephz are still involved in
much obscurity. Even in the large and fre-
quently examined physalus, it is difficult to
ascertain the functions of the various parts in
a satisfactory manner; and, accordingly, there
exists so much difference of opinion amongst
anatomists with regard to them, that some will
not even admit that it has a mouth, while
others assign to it both a mouth and an anus,
as well as cecal prolongations of the stomach.
Eschscholtz concluded, from his numerous ob-
servations on the living animals, that, in all the
physograda, the digestive organs consist merely
of absorbing tubes or suckers, all of which
are simple, and pendent from the inferior sur-
face. He seemed to think that the action of
these filamentary organs was analogous to that
of the roots of plants ;—that they were en-
dowed with an endosmosic power, which en-
abled them to imbibe nutritious matter from
the water. However this may be with regard
to the simple filaments, or cirri, it appears pro-
bable that the suckers are provided with orifices
at their extremities, through which proper ali-
mentary matter passes into the interior; for
several observers agree in stating, that both the
physograda, and the diphyda apply their
suckers to the bodies of other animals, and re-
main adherent to them for some time, during
which they seem to take up some nourishing
matter. Eudoxia has only one sucker. Messrs.
Quoy and Gaimard have described in detail
the singular filamentary organ which bears
these suckers in diphyes. Generally it is seen,
at first, only as a shapeless opaque mass, of a
reddish colour, lying contracted within the
swimming cavity. But, gradually, it is ex-
tended, and then there are perceptible, along
the whole of one side of a fine transparent tube,
numerous suckers, of a lengthened form ; each
is covered by a very delicate bell-shaped case,
and has its base surrounded by groups of mi-
nute vesicles, which are, probably, the ovaries.
From the base there arises also a little tenta-
cule or filament, susceptible of very great
elongation, and which sends off many secon-
dary filaments.*

The digestive organs of the ciliograda are
less dubious. In these we find uniformly a
straight alimentary canal with two orifices, the
mouth inferior, the anus superior, in the ordi-
nary position of the animal. In some species
there are lips formed by short and broad folds
of the integument, four in number, and very
sensitive. In cydippe, Dr. Grant found these
lips capable of rapid extension and retraction.

circle placed, throughout the greater part of its
course, immediately along the bases of the row of
tentacules that surround the disc, so as to form, as
it were, the outer wall of the circular vessel, or ap-
pendage of the intestinal cavity, which runs round
the margin of the disc. The same observer de-
scribes another nervous circle, composed of four
ganglion-like masses, disposed around the mouth,
each being in connexion with a corresponding group
of tentacules. (Ehrenberg, in Miiller’s Archiv
fiir Anat. Physiol., &c. 1834. p. 562.)
* Ann, des Sc. Nat. x. 8,

42

/

The mouth is large, the cesophagus straight and
wide; the stomach is, for the most part, of an
ovate form, the intestine passes in a straight
line, and with a uniform diameter, to its ex-
tremity. The anus has a promivent circular
margin in cydippe. No absorbent vessels can
‘be seen arising from the gastric cavity. In
many species, the alimentary canal is so large
as to occupy the greater part of the interior of
the body. When there is no food within it, it
remains open at both extremities, and, as the
animal swims generally with its mouth fore-
most, there is a current of water continually
passing through it. Eschscholtz observed, that
when suitable aliment was carried by this cur-
rent against the walls of the stomach, the
orifices were immediately contracted, and the
digestive process begun. Minute crustacea,
salpe, &c., have been found in the stomachs
of ciliograda. The diligent observer just men-
tioned seemed to regard the canal leading from
the stomach to the dorsal surface, (which we
have called the intestine,) as forming no part of
the digestive organs. He termed it “ the
water-canal,”’ and considered it as connected
merely with the peculiar mode of locomotion,
inasmuch as he observed it so patent while the
animal was swimming and not digesting as to
admit of a free passage for the water; which,
otherwise, in entering the open mouth, would
have much impeded progressive motion.

It was generally believed, until within a very
recent period, that some of the pulmograda
were destitute of stomachs. Hence the term
of agastric medusé which was applied to them
by Peron. The researches of Dr. Milne Ed-
wards, however, have rendered it probable that
this supposition was erroneous, and founded
on inaccurate observations. We have now rea-
son to believe that all the pulmograda have
gastric cavities; butall have not true mouths.
There are some in which the only communica-
tion between the stomach and the outer surface
is through numerous ramified canals in the
pendent arms, which open externally by ex-
tremely minute orifices, barely sufficient, even
in large species, to admit the smaller ento-
mostraca. Sucha structure exists in rhizostoma.
By injecting milk into its gastric cavity, the
canals in its arms, and their oscules can be
rendered visible; and it is then discovered
that from the minute oscules, which are situ-
ated in indentations along the margins of the
arms, small vessels proceed inwards, » and,
uniting in twos and threes together, open into
one large canal which runs through the middle
of each arm. These arms are large, fleshy,
foliated organs, eight in number; each of which
has atriangularshape. The eight canals above
mentioned unite two and two, so as to form
four great trunks, which open into a large
central cavity,—the only one in the body.
This cavity is situated at the base of the central
process pendent from the lower surface of the
disc. The base, in rising upwards, enlarges
into four fleshy columns, which lose them-
selves in the disc. It is between these four
fleshy columns that the cavity of the stomach is
placed. The intervals between the columns

ACALEPHE.

acirculating system. But Cuvier* was disposed

would form so many openings into this cavity
were they not closed tacaeiis and _plai d- rr
membrane, which bulges outwards when the —
stomach is filled. From the circumference of
the stomach, at equal distances, sixteen vessels
arise, and run directly towards the margin of the
disc. These vessels may be regarded as arteries, —
and will be hereafter described along with other —
structures more nearly resembling the ‘ot a

to consider them as ceca; although he ad-
mitted that he could discover no other vessels
fitted to discharge the functions of arteries.
He remarked that if we regard them as arteries,
we must look upon the little vessels which lead
from the appendages or arms to the central
cavity, as veins, or as lymphatics; and then
we might say that the sea is as a stomach
to the rhizostoma, in the same way as the
earth acts asa stomach for plants. But, at all
events, Cuvier was convinced by his dis-
sections that alimentary matter enters the body
through the marginal oscules of the arms,
and that it is accumulated in the internal cavity
before passing into the radiating vessels.
By experiments on the living animal, Dr.
Milne Edwards has recently proved+ that the
circumambient fluid and its contents of mi-
nute size do really enter the body of the
rhizostoma through the margins of the arms.
He placed a living rhizostoma in sea-water,
artificially coloured red. The animal did not
appear to suffer from the presence of the
colouring matter. Within a very short time,
the puckered membrane which borders the
arms was distinctly tinged red, and, gradually,
the colour ascended, until the whole body
assumed the same tint. Dr. Edwards does not
state, however, whether he traced the progress
of the coloured fluid through the brachial
canals and the vascular system. On placing
the same individual again in pure sea-water,
the colouring matter which had been absorbed
disappeared gradually, and it seemed to Dr. E.
that it was thrown out chiefly from the brachial
fringes, but partly also from the margin of the
disc, and from the capillary orifices situated at
the extremities of the arms. Dr. Edwards
satisfied himself that it is impossible for ani-
mals larger than small animalcules to enter the
central cavity of the rhizostoma. But most of
the pulmograda have large central mouths,
either simple and sessile, or placed at the ex-
tremity of a projection from the lower surface
of the disc. In some, the mouth is more or
less patent, but capable of being closed by the
approximation of the base of the arms. In
others it is surrounded by a ring of conside- —
rable density, in which muscular fibres can be
distinctly seen. In medusa aurita, there
Just within the cavity of the mouth, four open- —
ings, which lead, by as many short but wide —
canals, into four spherical sacs of consider ,
size. These are completely separated from —
one another by membranous partitions. That —
they are stomachs is proved by the circum-—

* Journ. de Phys. xlix. 438. _
+ Ann. des Sc. Nat. xxviii. 24). _

stance of fishes being found in them.* From
each sac, four vessels arise, which run out-
wards to the circumference of the animal.
Other species (e. g. medusa capillata) have the
four gastric sacs in free communication with
one another ; and, frequently, (e. g. in pelagia,
chrysaora, and @gina,) in connexion with these,
there are four other sacs, lined with a more
dense membrane than the former. These gas-
tric appendages have the form of simple canals
in eqguorea and timu ; and of branched vessels
in medusa and sthenonia.
They were chiefly such pulmograda as have
‘their dise bell-shaped that were formerly sup-
posed to be agastric. It was imagined that
alimentary matter being received within the
campanulate depression, its orifice was con-
tracted, and nourishment taken up by im-
bibition through the walls of the disc. But
an attentive examination of Carybdea mar-
_. supialis, (Peron,) one of the animals which was
believed to be agastric, has satisfied Dr. Milne
Edwardsthat a mouth and an internal cavity
connected with it do really exist. The great
transparency of this animal renders the dis-
covery of its internal structure a matter of con-
siderable difficulty, excepting when coloured
injections are used. Dr, Edwards found within
the funnel-shaped cavity of Carybdea, and, as
it were, pendent from its roof, a projection of
very delicate tissues, evidently forming tenta-
cula surrounding a central mouth, and a
stomach, from which proceed four long canals
leading to the tapering filaments which hang
down from the margin of the body of the
animal. These canals, Dr. Edwards believes
to be analogous to the radiating vessels of
thizostoma. There exists just at the com-
mencement of each canal, and opening into it,
a group of minute cylindrical sacs, which may
be regarded as biliary organs.+ But in most
of the pulmograda these organs are situated on
the margin of the disc. Generally, they pre-
_ sent the appearance of glands, being distinctly
a? im their structure. They are opaque,
' have a lengthened form, and are lodged in
little depressions, and surrounded by cup-
shaped folds of the external integument. They
are connected with the gastric appendages by
small tubes.{
In Aurelia phosphorea, (Lam.) ( Pelagia,
h.) which formed the principal subject of
llanzani’s observations on the acalephe,
_ there are four groups of membranous tubes,
convoluted, and resembling in structure the
estines of vertebrate animals. Although he
id not trace their connexions, Spallanzani
ppears to have regarded them as truly parts
the alimentary canal. He observed that
_ they exhibit a peristaltic motion, both in the
ee and in air, which can be increased by
the application of stimuli.§
The food of the pulmograda consists of
various marine animals—small fishes, mollusks,

_ _* Gaede, Beytriige zur Anat. tind Phys. der
_ Medusen.

+ Ann. des Sciences Nat. xxviii. 251.

t Eschscholtz, op. cit.
§ Travels, iv. 298. i

ACALEPHE.

43

crabs, and worms. Even large fishes are some-
times found entangled amongst the arms and
tentacules. They are probably killed by the
peculiar excretion which covers the surface of
these organs, and which produces a stinging
effect on man. The long filamentary appen-
dages which hang from the margins of the disc
in Carybdea and others, are covered witha
glutinous matter to which passing objects ad-
here; the animal has the power of stretching
them out and withdrawing them at pleasure,
and of so folding them inwards as to carry to
the mouth whatever may be attached to their
sides. It would appear that some species are
endowed with the power of discriminating the
food most suitable to their own nature. Gaede
remarks that he has never found fishes in the
stomach of medusa capillata, but often worms ;
while in that of medusa aurita there are fre-
quently fishes, rarely worms. In none of the
pulmograda have either masticatory or salivary
organs been discovered.

The cirrigrada have, in the middle of their
lower surface, a large flask-shaped stomach,
the mouth of which is formed like a sucker.
There appears to be a communication between
this organ and the numerous tentacula which
surround the mouth, through minute canals.
The food consists of small animals, such as
entomostracous crustacea; the undigested re-
mains of which are again ejected through the
mouth.

IV. Circulation—No distinct circulating
system has hitherto been discovered in the
acalephe. But perhaps the peculiar apparatus
of radiating vessels connected with the gastric
cavities in the pulmograda, and the aquiferous
canals of the ciliograda, which seem to per-
form nearly the same functions as the vascular
system of higher animals, may be conveniently
and properly considered under this head.

In the physograda, Eschscholtz saw what he
considered as the rudiments of a circulation ;
namely, distinct vessels arising from the roots
of the tentacula, and ramifying on the in-
ternal surface of the air-bladders ; but it does
not appear that he traced these further, or that
he saw the movements of a fluid within them.

The vessels in the ciliograda, within which
a fluid is seen to move, are situated chiefly
beneath the cilia-bearing arches. This fluid is
supposed by most modern anatomists to be
merely water; but by some it is regarded asa
peculiar fluid, the product of the animal’s
digestive powers. If it be water only, the
canals in which it moves must be considered
as being analogous to those of the aquiferous
system of other classes of invertebrate animals,
which has been so fully illustrated by the re-
searches of Delle Chiaje,* and which is pre-
sumed to be subservient to the respiratory
function. The vessels in question arise in
Berée from a vascular circle which surrounds
the intestine near the anus. They are eight in
number, and one runs beneath each cilia-bear-
ing arch, from one extremity of the body to

-*® Mem. sur la Storia e notomia degli animali
senza Vertebre, 4to. Napoli, 1823-20.

44

the other. They then terminate in another
annular vessel, which surrounds the mouth.
In their course they give off numerous
branches. From the oral circle of vascular
structure arise two large vessels, which run
along the walls of the gastric cavity, and ap-
pear to unite with the other circle at the anal
extremity. These last Eschscholtz regarded as
veins, and the eight external vessels as arteries.
He supposed that the veins, passing along
the walls of the stomach, absorbed the nutri-
ment, and then carried the circulating fluid to
the cilia for aération. In the course of his
observations on the Berve ovatus, Dr. Fleming*
distinctly saw a fluid moving “ backwards and
forwards” in the external vessels; and he states
that “ while the animal was active, there were
numerous small spaces in the different vessels
where the contained fluid circulated in eddies.”
Dr. Fleming failed to detect any structure in
the vessels which could produce these partial
motions. In cestum naiadis, Eschscholtz thought
that he saw the system of vessels more dis-
tinctly than in any other of the acalephe. He
thus described it: “ From the base of each of
the two tentacules, a vessel takes its rise, and
goes towards the bottom of the stomach. Here
the two vessels unite, and form a little vascular
circle around the water-canal (intestine). From
the upper margin of this circle, four straight
vessels arise, which go towards the two rows of
cilia-bearing organs placed on the dorsal sur-
face. Under these they run, two in one di-
rection, and two in the other. At either
extremity of the body, these unite with certain
vessels running superficially along the sides,
and which complete the circulation by entering
the first set of vessels just before they begin to
run beneath the ciliated organs. All these
vessels are simple canals, of the same diameter
throughout, without any visible branches. They
contain a colourless watery fluid, in which mi-
nute yellowish globules are seen to move. In
the vessels which arise from the bases of the
tentacules, the globules mount upwards ; they
assume a rotatory motion in the vascular circle;
and, in the four dorsal vessels, they seem to
move, some in one direction, others in the other.
It is probable that what appears to the eye as
one vessel, is, in reality, composed of two
vessels, running parallel and close together.”+

Seeing that the radiating vessels which arise
from the gastric cavities of the pulmograda
seem to carry out the nourishing material to all
parts of the body, and that they are, in some
species at least, connected with other vessels
which form a complete circle, we are disposed
to class them under this head along with the
vascular structures already described. The
exact analogies of their functions, however,
have not yet, we conceive, been distinctly
made out.

From the stomach of rhizostoma, formerly
described, sixteen vessels arise, and pursue a
straight course outwards to the margin of the
disc, near which they all enter, at equal dis-

* Mem. Wern. Soc. iii. 401.
t Op. cit. p. 14,

ACALEPHE.

tances, a circular vessel, which com-_

letely round the circumference of the animal.

our of the radiating vessels correspond with
the four fleshy pillars of the process supporting
the arms, and there exists on the internal sur-
face of each of these pillars, a groove, which
establishes a direct communication between the
corresponding vessel, and one of the large
vessels of the central process. The other
twelve are distributed by threes in the intervals
between the first four, and arise from those
parts of the stomach which are closed by the
plaited membranes. The space intervening
between the circular vessel and the margin of
the disc is occupied by an innumerable multi-.
tude of little vessels which form a net-work
like the finest lace.* In medusa aurita, there
are also sixteen radiating vessels, four of which
arise from each of the four sacs, into which the
gastric cavity in this species is divided. Two
of the four vessels in each group are simple,
the other two are several times bifurcated ;
both the simple main trunks and all the
branches so formed, enter a circular vessel sur-
rounding the disc, which seems to be connected
also with the tubular cavities of the numerous
cilia which surround the margin like a fringe,
and which are capable of elongation and con-
traction.t Carus remarks with regard to the
circular vessel, that “ it may be considered as
an extremely simple rudiment of the great cir-
culation of superior animals, in case we view
the radiating as chyliferous vessels.” }

V. Respiration.—It is probable that the air-
bladders of the physograda, the swimming
organs of the diphyda, and the cilia of the
ciliograda are all subservient, in a greater or
less degree, to the respiratory function, as well
as to locomotion. The vessels in the last men-
tioned class, which have been described above
as appertaining to the circulating system, are
regarded by some as respiratory organs; and
by Lamarck were compared to the trachex of
insects. They have been called aguiferous
trachee. Those who consider them in this
light believe that they are open at two points,
so as to admit the circumambient fluid to pass
freely through them. ‘The most recent and
accurate observations, however, leave it doubt-
ful whether this really takes place in the
ciliograde acalephe.

With regard to the pulmograda, several
parts and organs have been pointed out by
different observers as being, in all probability,
the seats of the respiratory function. Cuvier
thought that the delicate plaited membranes
which exist between the fleshy pillars of the
central process in rhizostoma, and which form
in part the walls of the stomach, might be re-
garded as the organs of respirarion. Eisenhardt
supposed that he saw them in certain tentacu-
lated processes attached to the membranous
partitions which divide the gastric sacs of some
Species from one another ; while Gaede looked
upon the four small sacs which overlie the

* Cuvier, Journ. de Phys. xlix. 438.
+ Gaede, Anat. der Medusen.
$ Carus, Comp. Anat. (by Gore,) ii. 266.

gastric cavities in medusa aurita as_ subser-
vient to the same function. These sacs com-
municate directly with the gastric cavities by
means of openings in the membranous par-
titions which separate them. The partitions
bear on their inferior surfaces, plaited mem-
branes, which, under the microscope, present
the appearance of being studded with vesicles
containing a little watery fluid. A row of
filamentary organs is also attached to these
membranes, which move like external cilia,
even for some time after they have been re-
moved from the body of the animal.

VI. Secretion—The existence of this func-
tion in the acalephe is made known to us by
the emission from their bodies, under certain
circumstances, of a glairy mucus; by the
Stinging effect which some unknown product
of their organization has upon our skin ; and
by the remarkable phenomenon of luminousness,
which a | number of them present. The
organs by which the mucus is secreted have
not been satisfactorily observed. Dr. Milne
Edwards saw reason to conclude with regard
to the rhizostoma, that a large quantity of this
fluid is secreted by a glandular structure
situated along the margins of the arms. The
stinging property possessed by several animals
of this class has been the subject of inquiry
since the time of Aristotle, but to this day
we remain in doubt with regard to the nature
and mode of production of the agent which
causes this effect. Some men seem to be in-
sensible to the irritation generally produced by
the contact of living acalephe. But, for the
most part, a slight touch of any part of their
surface, and chiefly of the pendent tentacula,
is followed within a few minutes, at most, by
a burning pain, redness, swelling, and some-
times even a vesication, of all that portion of
the skin which touched the animal. Sloane
said of the physalus, (“‘ what the seamen call
caravels, or Portuguese men-of-war,”) ‘ They
burn violently—they do suck themselves so
close to the skin that they raise blisters, and
cause sometimes St. Antony’s fire.’* Even on
our Own coasts, severe cases of inflammation
of the skin are occasionally seen, which have
been produced by the irritation received during
bathing from some of the larger pulmograda.
In peyeelus, the stinging property seems to
reside chiefly in the fluid with which the ten-
tacula are filled. It continues to act power-
fully even after the organs containing it have
been detached from the body. And not only
_ 80, but it is said by some observers that its
peculiar properties are so permanent, that
____ vessels in which the animals have been placed

must be washed several times in water, and
carefully scoured before they can be used
without inconvenience. On one occasion it
was found that linen, which bad been merely
rinsed in soap and water, had this quality of

25 oA BADER ERG ARG A ORE EE TIOeS Sew

is : By 8S he EN a A fle
ahh | he ete ate Ahi RL Ra ENS RE RAE CE ESD AR RE AS Ld DA a an a RARE om
- . . 7 F

* Nat. Hist. of Jamaica, ii. p. 273. Sloane re-
commends acajou oil as “‘ the remedy for the sting-
_ ing of this nettle.” Mr. Bennett has lately found
(Lond. Med. Gaz. xiv. 908.) that the application

of vinegar to the irritated surface in some degree
alleviates the pain,

=: .
« Pi

ESA INES Fe

ACALEPHE.

45

irritation fifteen days after it had been used in
making observations on the physalus.* None
of the cirrigrada hitherto examined possess
the stinging property.

e organs by which the luminous matter is
elaborated are unknown. In some species, it
is evidently mixed with the mucous fluid,
which is so abundantly poured out from the
margins of the arms and the disc. It has been
frequently observed that the ciliograda are
luminous chiefly along their rows of cilia, and
that these continue to emit light for some time
after their removal from the body. Perhaps
the greater number of the acalephe are lumi-
nous. According to Dr. M‘Culloch, all
inhabiting the British seas are so; and
indeed it is chiefly to the emission of light
by animals of this class that the beautiful
phenomenon of the luminousness of the sea
is owing in all situations. Spallanzani,
however, whose observations and experiments
on this subject were as extensive as they were
careful and ingenious, came to the conclusion
that “ the meduse which are possessed of lumi-
nous properties are extremely few compared
with those which are destitute of it.” The
same philosopher remarked, with regard to
some of the pulmograda, that they emit light
more strongly during the contractions of their
disc than at other times; that the intensity of
their light increases when they are pressed in
any way ; that the luminousness resides chiefly
in a peculiar fluid secreted by glands situated
around the margins of the disc, along the edges
of the tentacula, and in the fringed partitions of
the gastric cavities ; that this fluid being mixed
with other fluids, as with fresh and salt water,
and especially cow’s milk, imparts its lumi-
nousness to them ; that when spread over solid
bodies it continues to shine for several minutes;
and that in it there generally exists that irri-
tating substance which produces the stinging
effect. Spallanzani applied some of this fluid
on two occasions to the tip of his tongue. It
excited a burning sensation, which lasted more
than a day. A similar feeling, but much more
painful, followed the accidental application of a
single drop of the same fluid to the conjunctiva.+
In most of the acalephe, the external cover-
ing is very fine, smooth, and delicate; but
sometimes it is granular, or even warty. It
does not appear that these differences in its
structure have been observed by any naturalist
to be connected with corresponding differences
in the power of emitting light. (See Lumr-
NOUSNESS, ANIMAL.)

VII. Generation.—The organs of this func-
tion cannot always be satisfactorily ascertained.
This may, in a great measure, be owing to their
minuteness and transparency when not in
action. Ovaria and oviducts, however, are dis-
tinctly seen in several species; but no other
organs connected with the generative function
have hitherto been discovered. According to
Eschscholtz, the ovaria in the physograda con-
sist of several groups of vesicles and filaments,

* Journ. Roy. Inst. 1831, p. 205.
+ Travels in the two Sicilies, iv. 250.

46

loosely attached to the lower surface of the
air-bladder. In the diphyda, they are in the
form of numerous vesicles, having thick tunics
filled with an opaque white fluid, and situated
within one of their swimming organs. Such
arts were seen by Eschscholtz only in some
individuals, and on this account he was dis-
posed to regard them as ovaries. But Messrs.
Quoy and Gaimard seem to consider it more
probable that the minute botryoidal bunches of
vesicles, which surround the base of each
sucker on the lengthened filaments, (before
alluded to as being subservient both to nutri-
tion and to locomotion,) are the ovaries.*
It does not appear that
a either . Eschscholtz or
Messrs. Quoy and Gai-
mard saw the ova.

In the ciliograda, the
ovaries are more obvious.
They consist of two or
four vesicular organs,
each placed between two
of the cilia-bearing arches.
In cydippe, they are of a
red colour, and nearly cy-
lindrical shape. The ova
are spherical.

The parts in the pul-
mograda corresponding to
the organs just referred to,
are eight round bodies, of
small size, situated near
the margin of the disc,
each formed of a vesicle,
containing, at its free ex-
tremity, many minute
hexagonal _corpuscules ;
there is attached to each
vesicle a digitated appen-
dix, which seems to be hollow, and to com-
municate with the circular vessel. These
organs were seen by Gaede and by Miiller
in medusa capillata, and M. aurita, and by
Eschscholtz in some species of cyanea, sthe-
nonia, pelagia, and chrysaora; Dr. M. Ed-
wards has observed them also, at certain
seasons, in rhizostoma; and in carybdea mar-
supialis, he found, midway between each
pair of pendent filaments, and immediately
above a little notch in the margin, four
spots of a deep brown colour, each of which
appeared, under the microscope, to be formed
partly by a minute spherical body, having a
granular aspect, as if it were filled with eggs,
and partly by a little sac, with puckered sides,
which is imbedded in the gelatinous substance
of the body. These he regards as the ovaries.+
But, notwithstanding their having found gra-
nular bodies like ova in the organs above
described, neither Gaede nor Miiller considered
them as ovaries. Miiller regarded the granules
as excrementitious matters ; and Gaede thought
that he saw the ovaries in the plaited mem-
branes of the gastric cavities; whence he
observed the ova descend into certain minute

Coa

(Grace

A portion of the
ovigerous filament
of Diphyes much

magnified.

* Ann. des Sc. Nat. x. 8.
+ Ann. des Sc. Nat. xxviii. 259,

ACALEPHA.

vesicles imbedded in the margins of the arms.
He remarked that, in medusa qaurita, when the
cells in the arms were filled with eggs, the
laited membranes had none; and,onthe other
beat, when there were no eggs inthearms, the
plaited membranes were studded with them.
Cuvier was also of opinion that the ova are
formed in the plaited membranes above men-
tioned, and that they are matured in the mar-
gins of the arms.* ae
No observations, so far as we know, have

hitherto been made on the development of the
ova; but Dr. Grant has recently stated that the
ova of equorea are furnished with cilia, and
have locomotive powers, like the ova of the
porifera and polypifera.t The colours of the
acalephee often depend on the tints of their ova:
these are generally red, but sometimes brown,
yellow, or purple.
VIII. Geographical distribution—We con-
ceive that a brief notice of this part of their
natural history may, in some measure, illus-
strate the physiology of the acalephe. They
are met with in all seas; but certain families
exist more abundantly in some localities than
in others. The ciliograda and pulmograda,
for instance, are inhabitants chiefly of the colder
regions, while the physograda are seldom
found beyond the limits of the tropical zone.
Some float in bays, and near land, but the
greater number in the high seas. Meduse and
cyaneé are met with only in the cold and tem-
perate zones of the northern hemisphere. Cy-
dippe lives in the North Arctic Ocean, as well
as in the Pacific, under the equator. One species
of cestum inhabits the Mediterranean,—another
the South Sea. It frequently happens that
enormous numbers of one species are met with
closely grouped together, so as somewhat to
impede a ship’s progress for two or three suc-
cessive days; after which, not a single indi-
vidual of the same species is seen. In the
European seas, it is chiefly in summer and
autumn that the acalephe swim on the surface.
In winter, they probably sink to the bottom.

BIBLIOGRAPI'Y.—Madeer, Tentamen systematis
Medusarum stabiliendi, in Nova Acta Acad. Natur.
curios. vol. viii. Append. p. 19; and Papers in the
Svenska Vetenskaps nya Handlingar An. 1791,
transl. into Germ. s, t. Neue Abhand. der Schwed.
Akademie, &c. Jahr 1791; Seite 75, 149, 227.
Dana, De quibusdam urtice marine differentiis :
Miscel. Societat. Taurinens, v. iii. p. 206. Miiller,
Beschreibung zweier Medusen : Beschaeft. der Ber-
liner Gesellsch. Naturfor. Freunde Bd, 2. S. 290,
Cuvier, Sur Vorganization de quelques Meduses ;
Société Philomat, A. 3, F. 2, p. 69. Strém, A
paper in Danish on the Medusa palliata in the
Skrifter der Kiobenhab. Selskabs nye Saml. Deel. 3, —
S. 250. Swartz, Medusa pelagica beskrifven; —
Svenska Vetens. Acad. Hand. A. 1791, S. 188 in.
the German transl. T. 1791, S. 172. Gaede, Bey- —
traege zur Anatomie und Physiologie der Medusen, —
8vo. Berl. 1816. Quoy et Coie: Zoologie d’un —
Voyage autour du Monde, 2 vols. 4to. Atlas fol.
Paris, 1824. Duperrey, Voyage autour du Monde
4to. Atlas fol. Paris, 1826-1834, <r
(John Coldstream.)

* Régne Animal, second edit. iii. 277. See
Carus, Comp. Anat. ii. 307. Tb ‘eater ine
‘+ Lectures, Lancet, No. 565. p. 483. aS

‘

ACIDS, ANIMAL. ACRITA.

ACIDS, ANIMAL. — Several acids are
found in animal products, some of which are
peculiar to organized bodies, and others com-

- mon to them and to the other kingdoms in
nature. The former are characterized by their
analogy to other organic compounds, and are
ternary or quaternary combinations of carbon,
hydrogen, oxygen, and nitrogen. ‘The latter
are for the most part binary compounds, such
as the phosphoric, carbonic, muriatic, sul-
phuric, and fluoric acids.

With the exception of lactic acid, the exis-
tence of which as a distinct definite compound

_ is doubtful, there is only one acid which can
strictly be called peculiar to animals, namely,
the uric acid. The oxalic, benzoic, and acetic

; rag are common to animals and vegeta-

L es.

The other animal acids are not found ready
formed, but are artificially produced by various
chemical processes in which animal matters are
concern Such are the various acids from
fat and oil, the animal pyroacids, the purpuric
acid,* and a few others. There are also cer-

_ tain acids almost peculiar to individual animals,
such as the formic,+ the allantoic or amniotic,}

_ the bombic, &c.,§ and one or two which are the

products of disease.

Under the articles rat, URINE, MILK, and

BONE, will be found the details respecting the

_ principal animal acids.

(W. T. Brande.)

ACRITA (a, priv. xesvw, discerno,) a pri-
_ mary division of the animal kingdom founded b

_ Virey, and so called by Macleay,|| composed of
_ the lowest classes of the radiate animals of
Cuvier, and characterised by an indistinct, dif-
_ fused, or molecular condition of the nervous
system.

_ The necessity for a dismemberment of the
- Radiata of Cuvier, which Rudolphiff justly calls
_ a chaotic group, has been felt, and directly or
- indirectly expressed, by most naturalists and
_| Comparative anatomists.** It is impossible, in-
' deed, to predicate a community of structure
‘in either the locomotive, excretive, digestive,
‘Sensitive, or generative systems, with respect to
th division, as it now stands in the “ Régne
_ As in the animal organization the nervous

_ * First obtained by Dr. Prout from the pure
lithic acid, of which the excrements of the boa
onstrictor consist.
ed from the expressed liquor of ants.
u by Vauquelin to exist in the liquor
imnii of the cow,
~_ Extracted by Chaussier from the silk-worm,
but its existence is very problematical.
im: peers Entomologice, welch gp . ii, p. 202,
g peste Entozoorum, p. 572.
* Lamarck observes, ‘‘ Les animaux apathiques
‘(as he terms the Acrita) furent trés-improprement
ypelés zoop : ils ne tiennent rien de la nature
egétale, et tous généralemeut sont complétement
s animaux. La dénomination d’animaux ra-
yonnés ne leur convient pas plus que la précé-
‘lente ; car elle ne ‘peut s’appliquer ; qu’a une partie
@entr’enx; et il s’en trouve beaucoup parmi eux
qui n’ont absolument rien de la forme rayonnante.”
. n, sans Vertébres i. p. 390.

<
a
a
. :
a
> 7
T

OC

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47

system is that which is subject to the fewest
varieties, and as its relative perfection is the
surest indication of the relative perfection of
the entire animal, the modifications of this
system necessarily indicate the highest or pri-
mary divisions of the animal kingdom, and
form their distinguishing characters. .

Taking, then, the nervous system as a guide,
the radiata of Cuvier will be found to re
solve themselves into two natural groups, of
which the first, composed of the Polyastric In-
Jusoria of Ehrenberg, the Polypi of Cuvier,
the Entozoa parenchymatosa, Cuv. or Sterel-
mintha, and the Acalepha, differs in the absence
or obscure traces of nervous filaments from
the second division, including the Echinoderma,
the Entozoa cavitaria or Celelmintha, the epi-
zoa, and the Rotifera, Ehr., in which nervous
filaments are always distinctly traceable, either
radiating from an oral ring, or distributed, in a
parallel longitudinal direction, according to the
form of the body.

These different conditions of the nervous
system are accompanied with corresponding
modifications of the muscular, digestive, and
vascular systems, and a negative character, ap-
plicable to the higher division of Cuvier’s
Radiata, may be derived from the generative
system.

With respect to the muscular system, we find
that although all the Acrita possess the loco-
motive faculty at some period of their exist-
ence, and many never become fixed, yet that
distinct muscular fasciculi are not necessarily
developed. In the fresh-water polype, for ex-
ample, the whole of the homogeneous paren-
chyma of which it consists is equally con-
tractile; and even in the medusa, which ranks
among the highest of the Acrita, no distinct
muscular organs for effecting the contractions
of the gelatinous dise have yet been detected.
In the higher division of radiata, on the other
hand, which from the filamentous condition of
the nervous system may be termed Nemato-
neura, the muscular system is always distinctly
eliminated.

The difference in the condition of the diges-
tive system between the Acrite and Nemato-
neurous classes is still more striking: in the
former the alimentary canal is excavated in the
parenchyma of the body, and is devoid of dis-
tinct parietes: in the Nematoneura it is pro-
vided with a proper muscular tunic, and floats
in an abdominal cavity.

A corresponding difference is presented by
these two divisions of the invertebrate animals,
in the condition of the vascular system. Where
traces of sanguiferous organs are met with in
the Acrita, they are equally with the digestive
organ devoid of proper parietes, but consist
of reticulate canals in the substance of the
body, generally situated near the surface, and
in which a cyclosis of the nutrient fluids is
observed analogous to that of plants, but not
atrue circulation. This structure obtains in
the Acrita as low down in the scale as the poly-
gastrica, in which class Ehrenberg has deter-
mined the existence of a superficial network
of vessels containing an opaline fluid. In those

48

genera of sterelmintha or parenchymatous in-
testinal worms which manifest traces of the
circulating system, the fluids undulate in
canals of a similar structure, as is displayed in
the planariz, and parasitic trematoda, and also
in the echinorhynchi, in some species of which
genus the cutaneous canals form a rich net-
work.* In the acalephe the condition of the
vascular system is equally simple with that of
the lowest Acrita, as is exemplified in the mar-
ginal reticulate canals in the disk of the rhizos-
toma. In the Nematoneura, on the contrary,
those classes which manifest a circulating sys-
tem distinct from the digestive tube, as the
echinoderma and rotifera, possess vessels with
proper parietes, distinguishable into arteries
and veins.

No Nematoneurous class presents an example
of generation by spontaneous fision or gem-
mation, but these modes of reproduction are
common in the Acrite division.

The planarie among the sterelmintha are
capable of indefinite multiplication by simple
division; and the medusz are stated to pro-
duce, not ova, but ciliated locomotive gem-
mules or internal buds. The various examples
of these plant-like modes of generation which
the polypi and polygastrica present are fa-
miliar to most persons, and will be especially
treated of under their respective articles.

The fissiparous and gemmiparous modes of
reproduction are not, however, the exclusive
modes by which the Acrite classes are perpetu-
ated. Most of the sterelmintha are propagated
by means of ova: in the cystica and cestoi-
dea, the generative organs consist of ovaries
alone, or are cryptandrous; in the tremato.
da, a fecundating gland is superadded to the
ovary; while in the acanthocephala the sexes
are separate, so that thus early in the animal
kingdom, we find typified all the different
modes of generation by which the race is con-
tinued in the higher classes of animals.

The different conditions of the important
organic systems which are thus seen to obtain
in the great group of animals called Radiata
and Zoophyta fully justify a partition of
the group corresponding with those differ-
ences. For the lower organized division we
retain the name proposed by Macleay, but ex-
tend its application to the acalephe ; and thus
constituted it may be characterized as follows.

Sub-kingdom Acrita.—Gelatinous polymor-
phous animals, without distinct nervous fibre,
or visceral cavities.

Alimentary canalexcavated in the parenchyma
of the body, generally without an anus.

Sanguiferous system composed of reticulate
canals without proper tunics.

Generation in most fissiparous or gemmi-
parous ; in some oviparous.t

The Acrita have been termed Protozoa, as

* Rudolphi terms one species echinerhynchus
vasculosus, from this circumstance.—Synopsis Ento-

zoorum, p. 581.
+ The definition of the Acrita given by Macleay

is confessedly a negative one as referred to animals;
it is as follows :

ACRITA.

being on the first step of animal organization.
They are analogous to the ova or germs of the
higher classes, and have, therefore, been termed
by Carus Oozoa; and as the changes of the
embryo succeed each other with a rapidity
proportionate to the proximity of the ovum to

the commencement of its development, soalso.
we find that in each class of Acrita there are
genera which advance into close approximation __
with some one or other of the classes belong- __
ing to the higher divisions of the animal king- __
dom. It results, therefore, from this tendency _
to ascend in the scale of organization that there

is greater difficulty in assigning constant or gene-

ral organic characters to the Acrita than to any

of the higher divisions of animals. Even in

the nervous system, we find as we are led step

by step from the hydra to the actinia in

the class Polypi, that the nervous globules
begin to manifest the filamentary arrangement
about the oral orifice in the last named genus.
That, again, in tracing the successive complica-
tion of the sterelmintha from the hydatid to the
echinorhynchus we also come to perceive traces

of longitudinal nervous filaments in the latter
highly organized genus of parenchymatous
worms. In theacalephe the examples of the ag-
gregate form of the nervous system would seem

to be more numerous and distinct. Ehrenberg

has detected what he considers as a nervous sys-
tem in a gelatinous medusa; and Dr. Grant

has recently described a nervous collar giving

off simple filaments in the more highly or-
ganized beroé, which, in its distinct intestine
and anal outlet, recedes too far from the medu-
side to be placed in a natural arrangement in
the same class. Many of the polygastrica are j
endowed with simple visual organs or ocelli,
in the form of 5 or yellow spots; similar
organs of a dark colour are exhibited by the
planariz, and Nordmann also describes them
in some internal parasitic trematoda. Ehren-
berg has recently discovered coloured ocelli
in a medusa, and he ascribes a sense of
taste to the polygastrica.

The indications, however, of the special senses
in the Acrita are feeble and obscure, and in the
least doubtful instances the organs are evidently
of the simplest and most elementary nature.

For the most part all the different systems
seem blended together, and the homogeneous
granular parenchyma possesses many functions
in common.

Where a distinct organ is eliminated it is often
repeated indefinitely in the same individual.
Thus in the polypi the nutritious tubes of one
individual are generally supplied by numerous —
mouths, and it has, consequently, the semblance —

«« Animalia gelatinosa polymorpha, interaneis”
nullis medullaque indistincta.
**« Os interdum indistinctum, sed nutritio a .
tione externa vel interna semper sistit. Anus
nullus. <4
«* Reproductio fissipara vel gemmipara, gemmis
modo exteris, modo internis, interdum acervatis. —
«« Pleraque ex individuis pluribus semper cohe-
rentibus animalia composita sistunt.”—Hore Ento-
mologice, ii. p. 224. See also Lamarck, Anim.
sans Vertébres, ii. p. 2. =

ADHESION. —

of a composite animal; the polygastrica derive
their name from an analogous multiplication of
the digestive organ itself. Among the sterel-
mintha we find instances where the generative
system is the subject of a similar repetition,
each joint of the teeniz being the seat ofa separate
ovary, though all are nourished by continua-
tions of one simple system of nutritious tubes.
The calcareous and siliceous sponges, again,
which, in eliminating the first sketch of an in-
ternal earthy skeleton, seem to lose the few
characteristics of animal life which they before
possessed, are limited to the repetition of a
amie spiculum.
formative energies of the Acrita being
thus expended on a few simple operations, and
_ not concentrated on the perfect development of
any single organ, it is not surprising that the
different classes should exhibit the greatest
diversity of external figure.* But it has been
__ well observed that Nature, so far from forgetting
_ order, has, at the commencement of her work,
_ in these imperfect animals given us a sketch of
_ the different forms which she intended after-
wards to adopt for the whole animal kingdom.
_ Thus in the soft, sluggish sterelmintha we have
the outline of the mollusca ; in the fleshy living
mass which swrounds the earthy hollow axis of
_ the polypi natantes, she has sketched a verte-
_ brated animal ; and in the crustaceous covering
of the living mass, and the structure more
or less articulated of the polypi vaginati we
trace the form of the annulose or articulate
classes.

ra

( Richard Owen. )

__ ADHESION, (from ad-harere, Lat. adhesio,
_ Fr. adherence, Germ. wiederanheilung, Ital. ade-
sione, ) that process, by the occurrence of which,
when two living surfaces, naturally or artifi-
cially separated the one from the other, are
ight into mediate or immediate contact,
and inflammation is developed, those surfaces
) tay become adherent the one to the other.
This adhesion may be effected either by the
| intervention of a stratum of exhaled fibrino-
: minous matter, inorganic in the first in-
Stance, but at a subsequent period acquiring
ganization, and becoming a perfect and per-
anent cellular bond of union ; or it may not
cur until after suppuration has been estab-
ied and granulating surfaces are presented ;
ese surfaces enter into adhesion, and in this
ase the bond of union is not so decidedly
Hular in character as in the former ; it is more
less dense and fibro-cellular.
Tn either case, the medium of union pre-
peculiar modifications dependent upon
€ tissue on which itis developed. This circum-
tance, and especially the deposition of osseous
atter, where bony union is required, was one
the strongest arguments used for the purpose
establishing the existence of the presiding
telligent principle of Stahl.
If the first process, that in which the fibrino-
buminous exhalation obtains, be interfered
th, that is, if a more intense degree of in-

a b

his
LL

a * Macleay, ibid, p.-123.
| VOL, I.
}

49

flammation be developed, such exhalation can
no longer occur, but the second state, that in
which a purulent exhalation shall be the pro-
duct, may be induced.

It is upon this principle, viz. that a certain
quantity of inflammation shall predispose to
the first species of union, which is termed
union by the first intention ; and that a greater
quantity may produce a purulent exhalation,
and therefore be opposed to such union, that is
founded the following precept. ‘ When it is
deemed prudent to prevent union by the first
intention, we have merely to introduce between
the surfaces, and retain there from eighteen to
twenty-four hours a piece of lint, by which a
sufficient degree of inflammation will, usually,
be excited to ensure a suppurating surface.”

From the time when the phenomena of in-
flammation were first carefully studied, until
very recently, it has been commonly, if not uni-
versally maintained, that adhesion could never
be accomplished in the absence of inflamma-
tion.

In the present day, Breschet* and some others
have endeavoured to establish that adhesion
does not, necessarily, imply the pre-existence or’
co-existence of inflammation ; and as it appears
to me upon very insufficient evidence. They
say that adhesion may result from a “‘ primitive
disposition of the organization,” and as evi-
dence of the existence of this disposition, they
refer to certain congenital affections, occlusion
of the eyelids, and of the lachrymal canal,
imperforations of the mouth, the anus, and so
on. Why they should assume that phenomena,
the mechanism of which appears identical,
should be effected by a totally different agency
in intra and in extra-uterine life, it is not easy
to understand, and I believe such is not the fact.

We may have certain, of these occlusions,
accomplished in extra-uterine life, but never
without the intervention of inflammation; and
what possible reason have we for supposing

that if these occlusions do commonly, nay

always, occur in consequence of the develop-
ment of inflammatory action, that this agency
shall be wanting during uterine life? None, I
apprehend, beyond simple assumption.
Imperforation of the eyelids and occlusion
of the lachrymal canal differ from imperfora-
tion of the mouth and of the anus, in that the
former result, not from the presence of an
anomalous membrane, but only from the union
of existing membranes, which are normally
separated the one from the other. In the greater
number of cases the eyelids are simply adherent,
either at one or many points, or along the whole
length of their border, and I would say are
always so in consequence of inflammation.
The other imperforations to which allusion
has been made, are dissimilar to those of the
eyelids. Imperforation of canals opening upon
the surface of the body is a case in which, al-
most always, there has been an arrest of de-
velopment ; all the canals which in the adult
are lined by a mucous membrane, continuous
with the skin at their orifice, are naturally, at

* Dict. de Méd. art. Adhérence,
E

50

a

a certain epoch of embryo life, imperforate.
These organic states, which nosologists have so .
often considered as diseases, are, therefore,
simply primitive conditions preserved by ano-
maly, and become permanent instead of tran-
sient.* It may, therefore, be inferred that the
greater number of cases adduced as evidence
of adhesion in intra-uterine life are not in
point, and if they were it may still be asserted,
and the assertion be borne out by analogy,
that they had not occurred in the absence of
inflammation.

John Hunter seems to have had the idea that
adhesion may occur in the absence of inflam-
mation in certain cases, namely, in those where
blood has been effused, that this blood may
become organized and form a bond of union.
He says, “ It does not seem necessary that
both surfaces, which are to be united, should
be in a state of inflammation for the purpose
of effecting an union ; it appears only necessary
that one should be in such a state, which is to
furnish the materials, viz. to throw out the
coagulating lymph, and the opposite unin-
flamed surface accepts simply of the union ;
nor is it even necessary that ezther surface
should be in a state of inflammation to admit
of union: we often find adhesions of parts
which can hardly be called inflamed.”’+

I believe that no solution of continuity can
be obliterated in the absence of inflammation,
the injury which has occasioned the solution
of continuity, and the effusion of blood, being
sufficient to excite inflammation. The only
circumstance under which it seems to me to
be possible that union could be produced in the
absence of inflammation, is one which can only
rarely occur; and even then, although the
possibility of the occurrence can hardly be
denied, its reality may be reasonably ques-
tioned. If a portion of blood, for instance, be
effused into a serous cavity, its colouring
matter is, after a time, removed, and a fibrino-
albuminous coagulum remains. This coagulum
coming in contact with a previously uninflamed
serous membrane, may become united to this
membrane: and it is believed by some pa-
thologists that this union occurs without the
supervention of inflammation. Another si-
tuation where it is believed by certain patho-
logists that union is produced by similar
means, is in a portion of artery included be-
tween two ligatures, the blood which has been
included between the two points undergoing a
similar change to that which I have already
described, and adhesion of the clot to the in-
ternal tunic of the artery being effected in the
absence of inflammation.

Such cases may carry conviction to the mind
of a superficial observer, but a more careful in-
vestigation will lead to an opposite conclusion.
My own observations induce me to think, that
of all the causes by which adhesive inflam-
mation of serous membranes may be produced,
the most remarkable perhaps is an extravasation

* Isid. Geoff. St. Hilaire, Hist. des Anomalies de
V’Organization, t. i. p. §32.
+ On the Blood and Inflam. Ed. 1828, p. 319.

ADHESION.

of blood into their cavities, which appears to
excite just the precise quantity of inflammation
necessary for the production of adhesion. If
we examine the point at which such coagula
are maintained in contact with serous mem-
branes, before perfect union is established, we
shall find between the coagulum and the mem- _
branes a stratum of exhaled matter, the exist-
ence of which would lead to the conclusion —
that the clot has excited in the membrane as
much inflammation as is necessary for the pro-
duction of such exhalation. ;

In solutions of continuity where blood has
been effused between the edges, it was main-
tained by John Hunter* that this blood was
the provisional bond of union ; this, I appre-
hend, is not the case. Whether protected tom
the atmospheric air, which appears to exercise a
very decided influence in decomposing it, as in
some fractures, or directly exposed to it, as in
ordinary solutions of continuity, this coagu-
lum never, during the early periods, adheres
with sufficient firmness to attach to each other
the borders of a wound If, however, any por-
tion of the coagulum remain after a fibrino-
albuminous exhalation has been formed upon
the divided surfaces, it may become in this way
organised, and permanently adherent.

After the preceding remarks, it will therefore
be held in this article that whenever an adhe-
sion has been effected between two surfaces,
naturally or artificially separated, that that
adhesion must have taken place through the in-
tervention of inflammation ; that inflammation
arrived at a certain height will be accompanied
by a fibrino-albuminous exhalation ;—that if the
inflammation be carried beyond that point, a
purulent secretion may be established, and
when this is developed, union, by what is
termed the first intention, cannot occur ; granu-
lations are then developed, and union by what
is termed the second intention, may follow.
The process by which each kind of union is
effected I shall now proceed to describe in de-
tail.

In all cases, whether two naturally separate
tissues are to be united, or whether a solution
of continuity is to be repaired, there appears to
be a certain uniformity in the means by which
the union is accomplished. Inflammation is
developed, and a material susceptible of or-
ganization is exhaled, which becomes the con-
necting medium. This matter in its greatest
state of simplicity is exuded under the form
of lymph, upon the surface of the parts to be
united ; it is coagulated, and transformed into
a soft pulp ; it gradually increases in density,
acquires a reticular or porous aspect, a first
rudiment of organization, and as a second de-
gree exhibits in its substance red spots, then
strie, which have the appearance of vascular
ramifications, and at last bloodvessels. i:

It is hardly possible to collect this lymph it
a state of purity except in the canal of an arter
where it has been exhaled between two ligature
It is then presented under the form ofa whi
matter, of a soft and fibrinous consistence,

* Loc. cit. p. 253.

ADHESION.

is rendered icularly evident when the
lymph is submitted to the action of boiling
water ; it dissolves almost completely in a warm
solution of caustic potash, though less promptly
than thickened albumen, but more rapidly
than fibrine.

This matter, which is probably the same with
that by which all parts of the body are nourished
and preserved, but in the case before us secreted
in increased quantity and preserving a strong
tendency to coagulate, has nothing in it which
is necessarily opposed to the healthy action of
the animal economy. In fact we may consider
exudation as a nutrition, much exalted by in-
flammatory action, which is itself only an
exaltation of the vital properties.

We may admit four periods or states of
change to which this material which consti-
tutes the medium of adhesion is subject—
a first, the period of development; a second,
a period of increase; a third, that of organi-
gation; and a fourth, that of mutation; in
which it is changed into a cellular tissue.

In the first period, we find that in twenty-
four, and sometimes even in nineteen hours
after we have irritated a serous membrane, the
__ pleura of a dog, or of a rabbit for instance, that

this membrane is much injected, and that there
has been formed upon its surface an extremely
thin, pulpy stratum, which may very easily be
removed : the second period commences when
this exudation has assumed a membraniform
appearance, and is characterized by an aug-
mentation of thickness and of density : the third
period is characterised by still greater density
_and the presence of vessels. Stoll believed that
_ these membranes might become organised in
_ twelve, nine, or even eight days after the inva-
sion of the disease. Home believed that
_ vessels might appear in twenty-four hours.
. In the fourth period, the membrane loses
_ some of its thickness, and every day assumes
_ more and more of the appearance of cellular
| tissue; and when perfected, there is not only
' identity of appearance between cellular tissue
| and these membranes, but also, according to
_ Laennec,* identity of use, and even of disease,
_ except that this tissue very rarely contains adi-
_ pose matter.t
_ Nothing in our subject is more curious or
More important than the organisation of these
“membranes; their vessels are thin, delicate,
and similar to those of the pia mater; their
form and their direction are extremely simple ;
ey are not tortuous, and they proceed, usually,
‘in fasciculi, almost like the lymphatics of the
_ extremities. We may easily convince ourselves
tat their formation is sometimes very prompt,
y the sal of the following case. por-
ion of strangulated intestine, which, after the
neision of the herniary sac, did not present
many bloodvessels, was examined after the
death of the individual, which occurred in
twenty-nine hours after the operation, by Sir
Everard Home: he found the portion of in-
iu .

* De l’Auscultation Médiate, tom. ii. p. 293.
__ ¢ Laennec states that he has ‘* quelquefois ”” seen
fat developed in these cellular Jaminz. Loc. cit.—ED.

5i

testine which had been strangulated profoundly
inflamed, and covered in many points by a
* layer of coagulable lymph:” this intestine was
injected with very fine size, and two small
bloodvessels were found passing along through
the new membrane into which the injection
had penetrated.

According to Laennec* we may observe the
following phases in the organisation of these
membranes.

The rudiments of bloodvessels are at first
presented under the form of strie of blood,
which are more voluminous than the vessels by
which they are to be succeeded. The blood
appears to have penetrated into the tissue of the
membrane, as if pushed by a strong injection ;
yet in examining the points ofthe membrane,on
which the layer of “ coagulable lymph” is depo-
sited, we find no destruction, nor any orifice of
_a vessel, but only spots of blood. Soon, ac-
cording to Laennec, “ these lines of blood take
a cylindrical form, and ramify in the manner of
bloodvessels, still preserving a considerable
diameter. If, at this epoch, we carefully ex-
amine them, we find that these vessels have an
external coat which is soft, and formed of blood
scarcely concrete, to which they owe their
colour. After having incised this coat, we
withdraw a sort of mould, or rounded fasci-
cular body, whitish and fibrous, evidently
formed of concrete fibrine,and of which the
centre appears perforated and permeable to the
blood. Liowever small be the canal, it is these
fibrous fasciculi which should, bythinning, form
the tunics of the bloodvessels.”

These delicate observations have not, so far
as I know, been confirmed by other observers :
those authors who have spoken of newly deve-
loped vessels, among whom we may name
Hunter, Monro, Soémmering, do not speak of
this mode of development. Hunter and Home
ye ar it differently ; they say there is at first
a formation of small ampulle, containing only
a colourless fluid: second, a union of these
ampulla, and production of a vascular net-
work, not yet supplied with blood: third, an
inosculation between the newly developed
vessels, and those of the inflamed membrane,
and next the ingress of blood. Beclard was of
the same opinion.t Gendrin thinks that the
new vessels are developed by the action of the
primitive vessels ; he says, “ that the blood is
excreted by the adjoining capillaries, opening
into the soft and fibrinous tissue deposited in
the inflamed part; this blood becomes concrete,
and the vascular impulsion, a tergo, being con-
tinued, new blood is pushed into it and hollows
it. Thus the little vascular rudiment is pro-
longed into an irregular, flexuous, and unequal
stria, which meets another and unites with it,
continuing in this way to prolong itself into
the least resistent portion of the fibrinous de-
position.” {

_ To some extent the opinions of Laennec and

* Loc. cit.
t Anat. Générale, p. 195.
¢t Hist. Anat. des Inflam. tom. ii. § 1303. and
1571.
E2

52

Gendrin are alike ; they believe that the forma-
tion of the new vessel consisted in this, that the
little clot was perruaved , and that it was pene-
trated by liquid blood.

The experiments of Brande* would, however,
lead to a different conclusion ; he shewed that
the air contained in the blood had much in-
fluence in the formation of bloodvessels. This
air is carbonic acid gas, and its quantity appears
to be nearly equal in the two kinds of blood ;
being estimated at a cubic inch for every ounce
of blood. This gas may be separated from the
blood by the air-pump, and it escapes with a
kind of bubbling or effervescence, causing the
ascent of the mercury in a barometer attached
to the apparatus.

It has been remarked that during the coagu-
lation of the blood, a large quantity of carbonic
acid gas escapes; this coagulation, observed
under the microscope, has shewn that the gas,
by escaping in all directions, forms a net-work
of canals, the branches of which anastomose
with each other; and that this net-work pre-
serves its form after desiccation. It has also
been established that it is this gas which forms
those canals in coagulated blood; because, if
by means of the air-pump we deprive the blood
of it, before it is coagulated, they do not occur.

Sir E, Home has even injected the vessels
which were developed in the coagulum soon
after the blood was taken from a vein. Ifthe
formation of new vessels occur even in a coa-
gulum of blood removed from the living body,
but preserving still a certain quantity of its
heat, and of its vitality, with more reason might
we expect that a similar phenomenon should
obtain during life: and this fact has been de-
monstrated by experiments performed on a
rabbit, in which had been produced a hemor-
rhage from a small branch of the mesenteric
artery : after twenty-four hours, the coagulum
which was formed was injected.

The formation of vessels in coagulated blood,
by means of the carbonic acid gas which tra-
verses it in all directions, is in perfect accord-
ance with the observations which have been made
by M. Bauer upon germinating wheat, which
were instituted for the purpose of shewing the
influence of the globule of air. These globules
are manifested below a bud of mucilaginous
substance; they push it forward, elongate it,
and thus form a filament.

I do not, however, believe that either of
these theories correctly explains the pheno-
menon.

It was for a long time believed that false
membranes were never organised ; that nature
had given to the parts of our economy an
almost unlimited power of development, but
not the faculty of communicating life to the
produgs of the circulation; that false mem-

ranes appeared to be organised ‘only because
they constituted a kind of frame-work througli
which vessels from the inflamed tissue might
be prolonged: ulterior observations, however,
have shewn that these media are really or-
ganised. We have no general rules as to the

* Phil. Trans. 1818. pp. 172 and 185,

. ADHESION.

time when such organisation shall commence. —
It seems to be dependent upon inexplicable _
individual dispositions. It may, however, be
remarked, that the greatest analogy exists be-
tween the mode of development of vessels in

these media of adhesion and their mode of
production in the membrane of the yolk in the —
chick, saving always this remarkable cireum- —
stance, namely, the inconstancy, the irregu- —
larity of the work of organisation in the former, —
and, on the contrary, the constancy and the —
regularity of the occurrence in the latter
case. ;

These media are in fact secreted by a tissue,
the vitality of which is exalted to a certain
extent, and it appears to impress upon the
duct of its secretion a commencement of vitality, _
as in generation. All these circumstances ap-
pear to me to demonstrate that these vessels are
the product of a spontaneous generation—a true
epigenesis; so indeed, to a certain extent,
thought Hunter. He says, “ In a vast number
of instances [ have observed, that in the sub-
stance of the extravasation there were a great
number of spots of red blood, so that it looked
mottled. The same appearance was very ob-
servable on the surface of separation between
the old substance and the new, a good deal
like petechial spots. Was this blood extra-
vasated along with the coagulating lymph?
In this case | should rather have supposed it
would have been more diffused. I have there-
fore suspected parts have the power of making
vessels, and red blood, independent of the
circulation.””*

If the inflammation be not strictly confined
to that state in which the albumino-fibrinous
exhalation is accomplished, but proceeds to the
next stage, the exhalation entirely changes —
character; pus is produced, a granulating sur=
face is developed, and union is accomplished
by the intervention of another tissue, and by a
slower process than that which we have already
described. This is the process which is always
observed in mucous membranes, scarcely ever
in serous; for in the former, the albumino-fibri-
nous matter never becomes organised, and can
therefore never be the medium of a permanent
union. In these membranes, if adhesion occur,
the inflammation must proceed to the succeed-
ing stage. Adhesion of mucous membranes,
however, does not often occur—it is not com= —
patible with the performance of their functions. —

Soon after the secretion of pus is established
granulations are developed, and a state favour-
able to adhesion is produced. The develop-
ment of granulations occurs in the following —
manner :—upon the surface, about to suppurate,
is exuded a layer of “ coagulable lymph ;” this
lymph becomes penetrated by bloodvessels,
nerves, and absorbents, which give birth to
granulations. These granulations are developec
much earlier in some tissues than in others—
in a stump, for instance, we see them
upon the cellular tissue, then upon the mu:
cular, then the fibrous, and lastly upon th
osseous tissue: they appear to form as m ac

* Loc. cit. pp. 388-9.

more readily as the tissue may be more cellular
and vascular. That these organs are very vas-
cular is evident from the rapidity with which
they bleed upon the slightest contact ; that they

contain nerves is shewn by the pain which
is produced in them by the slighest touch:
does not their prompt destruction by slight
causes seem to indicate the existence of absor-
bents ?

No one has made more interesting researches
into the nature of these bodies than Sir Everard
Home.* He carefully observed the changes
which occurred in an ulcer of the leg. By using
a lens which enlarged objects eight times, he
saw that granulations were formed in the fol-
lowing manner: first, is seen a mass of capil-

lary vessels differently arranged; secondly,
small sinuosities containing pus. The ulcer ob-
served during ten minutes, offered, in the first
ee, an extremely thin and transparent pel-
icle, under which were disengaged globules of
gas, then canals having a horizontal direction,
and containing blood. The tunics of these
vessels were so delicate that they were ruptured
by the simple motion of the leg. These canals
anastomose with each other, taking different
directions ; those which are developed the first
were the next day changed into true vessels.
Soon these new vessels have enough of solidity
to admit of our passing a needle under them
and raising without rupturing them. The forma-
tion of all these parts is due, according to
Home, to the coagulation of pus, and the de-
velopment of carbonic acid gas; “ for if the
puriform matter be wiped off, these phenomena
are not produced.” When, on the contrary, he
employed substances, calculated to coagulate
the pus, the formation of those vessels was
accelerated. He concludes from his experiments
that bloodvessels are developed, almost as it
_ were under the eye of the observer ; that they
are not a prolongation of pre-existing vessels ;
that they are formed independently of the action
of the subjacent solid parts. So far, therefore,
‘although the processes may differ, yet the
_ general points of union between the two modes
is singularly similar.
_ While suppuration is proceeding

g, another
Operation is in progress under the layer of gra-
ulations. A stratum of cellular tissue, at first
Simple and not very resistent, afterwards fibro-
cellular, and lastly fibrous, is organised insensi-
bly to serve as the base of the succeeding me-
dium of union.
__ When granular surfaces are brought into con-
__ tact, and the tendency to secrete pus has ceased,
they enter into adhesion. This tendency is
marked by a diminution of activity in the gra-
ulations; the membrane ceases to secrete pus,
‘and the granulations become firmer and con-
‘tracted : before union can be effected, the sup-
‘purating surface must, therefore, change its
hature—must be destroyed. A state like that in
aple union by the first intention is produced ;
the secretion becomes plastic, and somewhat
_ analogous to that which accompanies that mode

* Home on Ulcers.

ADHESION. 53

When these new tissues or media of union
are developed between surfaces naturally free,
the structure of the two portions of the organ
between which they are seated becomes changed.
In serous or mucous membranes, as well as in
those surfaces which are immediate modifica-
tions of these two systems, this may be ob-
served. When, for example, the pleura costalis
becomes adherent to the pleura pulmonalis, the
point of union is no longer a serous membrane ;
the free surface having disappeared, an un-
interrupted continuity is established between
the subserous cellular tissue of the pleura cos-
talis, and the interlobular cellular tissue of the
lung. This conversion is frequent in the peri-
toneum ; in the tunica vaginalis a similar effect
is produced by the common operation for hy-
drocele ; in synovial membranes a similar effect
occurs in what is termed false ankylosis.

Having described the general laws by which
the phenomena of adhesion are governed, I
shall now point out, generally, the modifica-
tions which are impressed upon it in different
tissues.

It is upon serous membranes that we may
with most advantage study the process of ad-
hesion, not only because it is more rapidly
developed there, but because it much more
frequently occurs there than in other tissues.
If we examine the surfaces of two such mem-
branes which have been recently united, com-
mencing at a certain distance from the point of
adhesion, we see the layer of coagulable matter
effused between the two surfaces become thinner
as we approach the point of contact. If the
adhesion be sufficiently recent to admit of our
separating the surfaces, we see the intermediate
layer tearing, but remaining adherent to the
inflamed surfaces. If the inflammation be
more advanced, and the pseudo-membrane be
more dense and organised, we find that the
very thin layer of new deposition by which the
union has place is more resistent than the
thicker layer of organisable matter by which it
is surrounded ; and at a later period we may
discover vascular filaments attaching the ad-
herent portion of the new tissue to that upon
which it has been developed. These filaments
are as much more evident as the adhesion is
more immediate: of this we may very easily
assure ourselves by cutting transversely two
portions of digestive tube which have become
to a certain extent adherent by their external
tunic. The adhesion may be already very
solid at the points where contact is so imme-
diate that we can scarcely distinguish the in-
terposed matter. Very delicate red capillaries
creep through this matter, whilst perhaps at the
distance of some lines, and even at the centre of
an already organised point, the contact having
been less immediate, a plastic layer of one,
two, or more lines in thickness, may be seen
uniting the surfaces, but not presenting either
the solidity or the organisation of the exces-
sively thin layer which adjoins it.

When these adhesions have existed for a cer-
tain time, the serous structure completely dis-
appears. ‘This destruction of serous membranes
at the adherent point is very evident around

54

herniz which have been inflamed ; the intestines
engaged in the tumour are enveloped by a
more or less dense layer of cellular tissue ; and
hence many hernie thus circumstanced have
been described as having no hernial sac. This
sac has, however, originally existed, but has
disappeared by the adhesions which have been
formed between it and the displaced organs,
adhesions by which the cellular tissue which
replaces the serous membrane has been deve-
loped.

If we consider these adhesions in relation to
their frequency in the serous cavities, we see
that they exist most frequently in the pleura,
existing in nearly half the adult bodies ex-
amined. After the pleura comes the perito-
neum, then the pericardium ; those of the tunica
vaginalis are less common, but the arachnoid
is, of all serous membranes, especially relative
to its extent, that where these adhesions are
most unfrequent. :

The absence of mobility appears singularly
to favour this phenomenon: thus in the pleura
they most frequently occupy the superior parts,
and in the peritoneum most frequently occur
between the viscera forming a hernia, and be-
tween the convex surface of the liver and the
diaphragm.

The membranes between which such adhe-
sions occur, must usually, of course, be in
intimate relation, the one with the other
during the time when the process is in progress
of accomplishment, though now and then the
distance is considerable; but they may after-
wards become separated to great distances:
those cellular bands which are so commonl
seen in the thorax are evidences of this fact.

Some circumstances tend to demonstrate
that these bands in serous structure may ata
certain period of their existence be absorbed
and disappear, and the secreting surface be
reproduced. M. Ribes states that occasi-
onally we do not find any trace of such bands,
nor any adhesion in the peritoneum of persons
who have had penetrating wounds of the ab-
domen. Beclard examined an insane person
who had several times stabbed himself in the
abdomen. At the points where the more
recent of these wounds had been inflicted
considerable adhesions were found ; beneath the
older cicatrices no vestige of adhesion was
found. <A case of artificial anus occurred in
the practice of M. Dupuytren, by which fecal
matter passed during twelve days. The pa-
tient died at the end of seven months. At the
examination after death, it was found that the
portion of intestine in which the accidental
opening had existed, was distant from the ab-
dominal cicatrix between four and five inches.
A very attenuated cellular band extended from
the cicatrix to the portion of intestine. Doubt-
less a short time would have sufficed for the
absorption of this band, when the intestine
pseitt | have . been set at liberty and the serous
surface restored.

In the course of lectures which Bichat de-
livered only a few months before his death,
he maintained that adhesion was never pro-
duced between mucous surfaces, and that con-

ire
2 Ne

-

=

=

‘

ADHESION.

sequently the cavities lined by this tissue were

never obliterated. Few statements have given —
rise to more extensive discussion than this;
few discussions have up to the present moment
been attended by less satisfactory results. In
his first dictum I believe he was clearly right,
in the second as clearly wrong.

Mr. Hunter’s opinion was in accordance
with that of Bichat: he says, “ that in all the
outlets of the body called mucous membranes,
the order of inflammation differs from that
which occurs in cellular membrane, or in cir-
cumscribed cavities. In these latter adhesive
inflammation is immediately admitted to ex-
clude, if possible, suppuration.” In internal
canals, where adhesions would in most cases
prove hurtful, the parts run immediately into
the suppurative inflammation, the adhesive in-
flammation being in common excluded.*

Mucous membranes, when unchanged by
disease, are not capable of becoming adherent
the one to the other, and the reason of this is
simple. 1 have already stated that no per-
manent adhesion can occur in the living bod
without the intervention of a new tissue, whic
at a certain indefinite or undetermined period
of its existence becomes organized.

A pseudo-membrane of considerable extent
may be thrown out upon an inflamed mucous
surface; but this membrane, 1 apprehend,
never becomes organised, and union between
mucous surfaces cannot therefore be permanent
unless some other agency be called into action.
But, as soon as inflammation has destroyed the
characters from which these membranes derive
their name; when the mucus, which like an
inorganic layer appears to oppose itself so
successfully against immediate contact, thereby
preventing the organization of the effused mat-
ter, no longer exists ; when the cellular element
which forms the basis of this membrane is
developed, then adhesion by means of the
union of granular surfaces is effected with the
greatest facility; of this we have evidence in
most of the mucous canals. It is not rare,
for instance, to meet with complete obliteration
of the vagina, of the cystic duct, and so on.

It is stated very generally that the opinion
of Bichat is entirely unfounded ; that inflam-
mation of the vagina is followed by complete
occlusion, without destruction or transforma-
tion of the mucous membrane, and that similar
effects may occur in the Fallopian tubes, the
uterus, and other mucous canals. That these
are produced is perfectly true, but never until
the disorganization to which I have alluded
has occurred.

It is maintained triumphantly as a con-
firmation of the opinion that no transformation
occurs, that when these adhesions are sepa-
rated, we have the healthy mucous membrane
performing its functions as before. This, how- —
ever, is not the case; the membrane is essen- —
tially different, and it is not without difficulty —
that we can overcome its tendency to enter —
into adhesion again. That a membrane is pro-
duced, which performs functions analogous to

* Loc. cit. p. 305,

ADIPOCERE.

the primitive membrane, is true. If we ex-
amine a fistulous canal which has existed for
a certain time, we find it invested by a mem-
brane similar in appearance, and performing
an analogous function to the primitive mucous
membrane,—so rapidly does nature under cer-
tain circumstances adapt an organ to the per-
formance of the function to which it is des-
tined.
As it is therefore upon the organization of
_ this pseudo-membrane that the species of union
of which I am treating is dependent, some re-
mark upon that subject becomes necessary. It
has been maintained by Albers, Soemmering,
and Larrey, that these new formations upon mu-
cous membranes may become organized. The
former of these gentlemen believes that the
false membrane of croup is commonly organ-
ized. Soemmering, it is said, possessed pre-
ions which demonstrated the fact. Cail-
eau* supports this opinion, as well as Vil-

lermé+ and Guersent.t I have never seen
this membrane present the slightest vestige of
organization, nor have I ever found any one,
with the exceptions I have named, who has,
although, to my knowledge, they have been
sought for during many years, by a number
___ of the most competent observers of the present
_ day. And as I believe the investigations of
morbid phenomena are more accurately made
at present than at any former period, I adhere
to the opinion that organization of these mem-

_ and that union by “ the first intention” can
never occur in those canals which are invested
by mucous membrane. But when the com-
— of the mucous membrane becomes
estroyed or disorganized by inflammation, and
a granular surface is presented, adhesion may
_ be and is frequently produced.
___ The epidermis with which the skin is fur-
_nished forms an inorganic stratum which is
y opposed to all adhesion; but remove this
_ epidermis, render the surface bleeding, or sup-
' purating, and adhesion may be produced with
_ the greatest facility. It is against this ten-
dency we have constantly to struggle for the

vt

-

_— of preventing the adhesion of fingers
each other, to the palm of the hand, and
© on,—so common a consequence of burns.
_ Adhesion may in this tissue occur, therefore,
J by the development of the fibrino-albuminous
medium, or by that of granulations. The
“Synovial membrane of joints may become
erent, constituting a species of ankylosis,
which is termed “false.” In these cases the
_ Secretion of synovia diminishes and ultimately
_ ceases, the contiguous surfaces lose their polish,
rugous, and contract adhesions. (See
Jotnts.) In osseous tissues, adhesion may
be effected either through the agency of the
albumino-fibrinous exhalation already de-

tibed, or that of granulations. (See Bone.)
1 cartilaginous tissues the mechanism of ad-

‘ Tere

* Rapport du Concours sur le Croup.
+ Dict. des Sc. Méd. tom. xxxii. p. 260.
$ Dict. de Méd art. Croup.

branes upon mucous surfaces never occurs;

55

hesion is different; and in speaking of the
process in these tissues, it is necessary to di-
vide the tissue into those which are invested
by a more or less dense fibrous perichondrium,
and those which are without it.. To the first
appertain the cartilages of the ribs, of the
larynx, and all those which Bichat termed fibro-
cartilages. ‘The second class comprehend the
diarthrodial. It is in fact, I believe, upon the
presence or absence of the perichondrium, that
are dependent the principal differences which
are presented in the pathological condition of
these organs. The non-diarthrodial as well
as the fibro-cartilages, when they are ruptured
or divided, are not united by a cartilaginous
substance.

In the wounds of cartilages, with loss of
substance, there is formed a kind of cellulous
matter, which is a secretion from the perichon-
drium ; in fact no phenomena of reproduction
are observed where this membrane does not
exist; thus it is never observed in diarthrodial
cartilages. We may cut and mutilate these
latter, and after many days we shall find the
wound almost as it was on the first day.
When the cartilages of the ribs are ruptured,
their union is often effected by an osseous ring
which surrounds the two fragments. See the
articles ARTERY, ENcEpHaton, Nerve, Fi1-
BROUS TISSUE, Musc er, VEIN, for the pheno-
mena of adhesion in these structures.

BIBLIOGRAPHY.—Freeke, on the art of healing,
cicatrising, incarning, &c. 8vo. Lond. 1748. Bezoet,
De modo quo natura solutum redintegrat. 4to.
Lugd. Batav. 1763. (Rec. in Sandifort Thes. Diss.
vol. iii, p. 147.) Spallanzani, Prodromo, &c.
sopra la reproduzione animali, 4to. Modena, 1768.
Ejus, Upuscoli de fisica, &c. 2 vol. 8vo. Modena.
1776. Eyting, De consolidatione vulnerum. 4to.
Argent. 1770. Moore, On the process of nature in
the filling up of cavities, healing wounds, &c. 4to.
Lond. 1789. Nannoni, De Similium partium corp.
hum. constit. regeneratione. (In Roemeri Delect.
Opuse. Ital. vol. i.) Arnemann, Versuche ueber
die Regeneration an lebenden Thieren. 8vo. Gotting.
1782. Murray, De redintegratione partium, &c.
8vo. Cassel, 1786. Bell, Discourses on wounds.
8vo. Edin. 1795—1812. Balfour, Obs. on Adhe-
sion. 8vo. Lond. 1815. Stoll, Ratio Medendi, pars
v. & vii. 8vo. Vienna, 1768. Hunter on the Blood,
Inflammation, &c. Bichat, Anatomie Gén. Beclard,
ditto. Breschet, Dict. de Méd. art. Adhérence.
Cruveilhier, Dict. de Méd. et Chir. Prat. art.
Adhesions. Laennec, De |’Auscultation Médiate,
tom. ii. pp. 111, et seq. Brande, in Phil. Trans.
1818. Gendrin, Hist. Anat. des Inf. passim.
2 tom. Paris, 1826. Andral's Pathological Ana-
tomy. Home on Ulcers, 8vo. Lond. 1801.

( Benjamin Phillips. )

ADIPOCERE, from adeps and cera: a term
given to a peculiar fatty matter, somewhat re-
sembling spermaceti in appearance, and sup-
posed to partake of the properties of fat and
wax. In the year 1789, Fourcroy communi-
cated to the Royal Academy of Sciences at
Paris a curious account of the changes sus-
tained by the human bodies interred in the
cemetery of the Innocents in that city; some
of these had been piled, for a succession of
years, closely upon each other, in large cavities
containing from one thousand to fifteen hundred.

56

individuals. One of these graves, opened in
Fourcroy’s presence, had been full, and closed
for fifteen years. When the coffins were opened,
the bodies appeared shrunk and flattened, and
the soft solids were converted intoabrittle cheesy
matter, which softened and felt greasy when
rubbed between the fingers. The bones were
brittle ; and the texture of the abdominal and
thoracic viscera no longer discernible, but
lumps of fatty matter occupied their places.

It is not uncommon to find masses of this
adipocere in the refuse of dissecting-rooms,
especially when heaps of such offal are thrown
into pits and wells, and suffered gradually to
decay. The carcases of cats and dogs and
other drowned animals also often exhibit more
or less of a similar change; and Dr. Gibbes
(Phil. Trans. 1794) found that lean beef, se-
cured in a running stream, underwent a change
into fat in the course of three weeks. Fat, and
the adipose parts of animals, also undergo a
change in appearance and composition under
similar circumstances: tallow becomes brittle
and pulverulent, and may be rubbed between
the fingers into a white soapy powder.*

Gay Lussac, Chevreul, and some other emi-
nent chemists, conceive that muscular fibre, skin,
&c. is not convertible into adipocere, but that this
compound results entirely from the fat originally
present in the substance, and that the fibrin
is completely destroyed by putrefaction. There
are cases, however, in which the conversion
of muscle and of fibrin into fat can scarcely
be doubted, (Annals of Philosophy, xii. 41,)
though the propriety of applying the term adipo-
cere to such fatty matter may be questionable.
The action of very dilute nitric acid upon some
of the modifications of albumen is also attended
by their conversion into an adipose substance.

The chemical properties usually ascribed to
adipocere are the following: it fuses at a tem-
perature below 100°; it dissolves in boiling
alcohol, and the greater portion is deposited as
the solution coois; the action of ether resembles
that of alcohol; it is saponified by the fixed
alkalies, but not by ammonia. It would ap-
pear, however, from Chevreul’s experiments,
that adipocere is not a mere modification of
fat, or a simple product, but that it is a soap
composed of margaric acid and ammonia.
These combinations of adipose substances and
their further chemical history will be given
under the article Far.

BIBLIOGRAPHY.—Fourcroy, Acad. Rle.des Sciences
de Paris, 1787. Gibbes, Conversion of animal
muscle into a substance resembling spermaceti.
Phil. Trans. 1794. Conversion of animal sub.«
stances into fatty matter. Phil. Trans. 1795. Vide
also Annales de Chimie, t. v. 154 ; t. viii. 17—72-
Crell’s chemische Annalen for 1793 and 1794 ; and
John’s Tabellen. 1, B. p. 35.

( W. T. Brande. )

* If a portion of the fatty degeneration of the
liver be immersed for some time in water, it will
furnish an excellent specimen of adipocere. The
writer of this note had lately an opportunity of
observing the process of the conversion of a large
portion of liver into this substance.—R. B. T, ~

ADIPOSE TISSUE.

Fr. tissu adipeux, tissu graisseux, Germ. das

ADIPOSE TISSUE.—(Lat. Tela adipose

Fett, Ital. adipe. peers ey am
Many of the old anatomists, as Mondini,
Berenger, Vesalius, and Spigelius, represent
the fat (adeps vel pinguedo ) of the animal body
as entirely distinct from the membrana carnosa,
or cellular membrane, The separate existence
of a proper adipose membrane, however, si-
tuate between the skin and the filamentous —
tissue, or membrana carnosa, was first taught
by Malpighi, then distinctly maintained by
De Bergen and Morgagni, and finally demon-
strated by William Hunter. Collins, James
Keill, and other anatomists adopted the views
of Malpighi, and Haller was disposed latterly
to imitate De Bergen and Morgagni, in assigning
to the fat of the animal body a situation dis-
tinct from that of the cellular membrane. And
in this country the independent existence of
the adipose membrane was recognized by
Bromfield, John Hunter, and others.

It was still, however, confounded with that
of the filamentous tissue under the general
name of cellular membrane, adipose mem-
brane, and cellular fat, by Winslow, Dionis,
Portal, Sabatier, Bichat, and Meckel, and
described as a variety or modification of the
cellular membrane; and Blumenbach considers
it as a secretion into that membrane. Its dis-
tinct existence from the cellular membrane was
finally admitted by M. Beclard, and its anato-
mical and physiological relations as well as its
chemical properties have been since minutely
investigated by M. Raspail.

According to the dissections of De Bergen
and Morgagni, the demonstrations of Hunter,
and the observations of M. Beclard, the struc-
ture of the adipose membrane consists of
rounded packets or parcels ( pelotons ) separated
from each other by furrows of various depth, of
a figure irregularly ovoidal, or spheroidal, va-
rying in diameter from a line to half an inch,
according to the degree of obesity in the
part submitted to examination. Each packet
1s composed of small spheroidal particles which
may be easily separated by dissection, and
which are said to consist of an assemblage of
vesicular bags still more minute, aggregated
together by very delicate filamentous tissue.
These were originally described by Malpighi
under the name of membranous saccwli, and
by Morgagni under that of sacculi pinguedi-
nOSi.

The appearance of these ultimate vesicular
pouches is minutely described by Wolff in the
subcutaneous fat, and by Clopton Havers* and
the first Monro in the marrow of bones, in —
which the two last authors compare them to —
strings of minute pearls. If the fat with which —
these vesicles are generally distended should —
disappear, as happens in dropsy, consumption,
chronic dysentery, and other wasting diseases,
the vesicular sacs collapse, their cavity is obli-_
terated, and they are confounded with the con-

* Osteologia Nova, Lond. 1691, and Obs. Nov.
de Ossibus, Amst.1731, ty eis

i

ADIPOSE TISSUE.

tiguous cellular tissue without leaving any trace
of their existence.

Hunter, however, asserts that in such cir-
cumstances the cellular tissue differs from the
tissue of adipose vesicles in containing no
similar cavities, remarks that the latter is much
more fleshy and ligamentous than the _fila-
mentous tissue, and contends that though the
adipose vesicles are empty and collapsed, they
still exist. When the skin is dissected from
the adipose membrane, it is always possible
to distinguish the latter from the filamentous
tissue, even if it contain no fat, by the tough-
ness of its fibres and the coarseness of the web
which they make.

The distinguishing characters between the
cellular or filamentous and the adipose tissue
may be stated in the following manner. First,
the vesicles of the adipose membrane are closed
all round, and, unlike the cellular tissue, they
cannot be generally penetrated by fluids which
are made to enter them. If the temperature
of a portion of adipose membrane be raised
by means of warm water to the liquefying
point of the contents, they will remain un-
moved so long as the structure of the vesicles
is not injured by the heat. If again an adi-

se packet be exposed to a solar heat of 104°

ahrenheit, though the fat be completely lique-
fied, not a drop will escape until the vesicles
are divided or otherwise opened, when it ap-
pears in abundance. The adipose matter,
therefore, though fluid or semifluid in the
living body, does not, like dropsical infiltra-
_ tion, obey the impulse of gravity. Secondly,
_ the adipose vesicles do not form, like cellular
tissue, a continuous whole, but are simply in
mutual contiguity. This arrangement is de-
_ monstrated by actual inspection, but becomes
more conspicuous in the case of dropsical effu-
sions, when the filamentous tissue interposed
_ between the adipose molecules is completely
_ infiltrated while the latter are entirely unaf-
| fected. Thirdly, the anatomical situation of
| _ the adipose tissue is different from that of the
| filamentous tissue. The former is found, 1st,
_ ina considerable layer extended immediately
Xeneath the skin; 2dly, in the trunk and ex-
-tremities round the large vessels and nerves ;
‘3dly, between the serous and muscular tissues
of the heart; 4thly, between the peritoneal
olds which form the omentum and mesentery ;
‘Sthly, round each kidney; and, 6thly, in cer-
tain folds of the synovial membranes without
the articular capsules.
_ In each of these situations it varies in quan-
tity and physical properties. In the least cor-
-pulent persons a portion of fat is deposited in
the adipose membrane of the cheeks, orbits,
palms of the hands, soles of the feet, pulp of
th — and toes, flexures of the joints,
round the kidney, beneath the cardiac serous
m ne, and between the layers of the me-
Sentery and omentum. In the more corpulent,
chiefly in females, it is found not merely
these situations, but extended in a layer of
thickness, almost uniformly over the
Whole person; but is very abundant in the

>

qj

we ltaeiue

4

*

57

neck, breasts, belly, mons Veneris, and flexures
of the joints.

It has been long observed that the subcu-
taneous adipose layer presents considerable
differences from the adipose matter found be-
tween the folds of the serous membranes ; and
the older anatomists, aware of these differences,
distinguished the former by the name of pin-
guedo, and the latter by that of sebum. The
subcutaneous adipose membrane is, when
viewed as a whole, more elastic, softer, and
less granular than the omental fat, and evi-
dently presents the arrangement of vesicular
bags much more distinctly than the omental.
It is in the subcutaneous adipose membrane
indeed, almost exclusively, that the vesicular
arrangement can be recognized. The subcu-
taneous cellular fat also contains a greater
quantity of oil than the omental, which abounds
chiefly in firm, brittle, granular fat.

The situation where the vesicular structure
of the adipose membrane is most easily de-
monstrated is in the hips between the skin
and the gluteal muscles, and at the flexures of
the joints generally. In the former situation
especially, the constituent fibres of the vesi-

cular bags are tough, firm, and ligamentous,

and the bags themselves are large and distinct.
It is a remarkable anatomical character of
the sebaceous or tallow-like fat that its distri-
bution is confined chiefly to the external or
commutual surfaces of several of the serous
membranes; and this arrangement presents a
series of interesting anatomical analogies. Thus
sebaceous fat is found on the external surface
of the pleura costalis, between it and the inter-
costal muscles, and between the layers at the
posterior and anterior mediastinum. It is also
found between the cardiac pericardium and the
muscular substance of the heart, especially
around the vessels of the organ. In some of
the large mammalia even this circumstance is
connected with peculiar anatomical appear-
ances. Thus, in the heart of the dolphin (ded-
phinus tursio,) we find the cardiac pericardium
formed into broad prominent fringes, consisting
each of two folds of the membrane, between
which is interposed a considerable quantity of
sebaceous fat. In the same manner the several
omenta, or peritoneal duplicatures in the abdo-
men, may be recognized as analogous fringes
containing more or less sebaceous fat; and the
omental appendages (appendices epiploice ) of
the colon must be regarded as examples of the
same arrangement. Lastly, in the interior of
the articular capsules we find the synovial
membranes forming large prominent fringes,
which, if immersed in water, show to what
extent they are made to recede from the cap-
sule and bone, and forming cavities of dupli-
cation in which sebaceous matter is contained.
It thus appears that none of the serous mem-
branes is exactly applied either to the parietes
of cavities or to the surface of the contained
organs, but that they form intervals on their
outer or attached surfaces, on which various
quantities of sebaceous fat are deposited. In
all these substances we do not recognize the

58

same distinct arrangement of an appropriate
organ, but simply masses of adipose, or rather
sebaceous matter, interposed between the at-
tached surface of the serous membranes and
the adjoining or the contained organs.

Fat occurs in a third modification in the
marrow of bones, The adipose granules, which
are soft, whitish-yellow, and oleaginous, are
here contained in a peculiar membrano-cellular
web, forming numerous vesicles, which may be
regarded as an ultra-osseous adipose tissue. It
is a remarkable proof of the influence of the
vital principle that during life the substance of
the bones is never tinged with this animal oil,
but the moment life is extinct, the marrow
begins to transude and impart to the bones a
yellow tint and a greasy aspect.

Fat, though chiefly observed to occur in the
bodies of animals, is nevertheless not confined
solely to these bodies. Thus not only do va-
rious kinds of oil and consistent oleaginous
matter occur in certain vegetables, but sub-
stances similar even to tallow are found in
some vegetable productions. A _ sort of
tallow is obtained from the vateria Indica, a
forest-tree of the camphor family, indigenous
in the Indian Archipelago. In a species of
croton indigenous in China, namely, the croton
sebiferum of Linneus, the stillingia of Mi-
chaux, or tallow-tree, the seeds are covered
with a quantity of fat, bearing so close a re-
semblance in all its properties to tallow, that it
is used by the Chinese in the manufacture of
candles; and the fruits of the a/eurites triloba,
a native of the Sandwich Islands, of the same
natural family with the croton, are the candle-
nuts of the inhabitants of these remote regions.

It is chiefly in the subcutaneous layer that
the organization of the adipose membrane has
been investigated. The constituent vesicles or
bags consist of firm, tenacious, ligamentous,
gray, or whitish-gray coloured substance, mu-
tually united by means of delicate filamentous
tissue. These vesicles or sacs receive arterial
and venous branches, the arrangement of which
has been described by various authors, from
Malpighi, who gave the first accurate account,
to Mascagni, to whom we are indebted for the
most recent. According to Malpighi,* the
bloodvessels divide into minute ramifications,
to the extremities of which are attached the
membranous sacs, containing the globules of
fat-so as to bear some resemblance to the leaves
attached to the footstalks of trees. These ve-
sicular or saccular arteries are afterwards di-
vided into more minute vessels, which then
form upon the vesicular sacs a delicate vascular
network. According to Mascagni, who repre-
sents these vessels in accurate delineations, the
furrow or space between each packet con-
tains an artery and vein, which, being subdi-
vided, penetrates between minute grains or adi-
pose particles, of which the packet is composed,
and furnishes each component granule with a
small artery and vein. The effect of this ar-

‘¢ ge Omento, Pinguedine, ct Adiposis Ductibus,
Pp. 4 .

ADIPOSE TISSUE.

rede . *

rangement is that each individual grain or
adipose particle is supported by its artery and
vein as by a footstalk or peduncle, and those of
the same packet are kept together not only by
contact, but by the community of ramifications
from the same vessel. These grains are so
closely attached that Mascagni, who examined
them with a good lens, compares them to a
cluster of fish-spawn. Grutzmacher found
much the same arrangement in the grains and j
vesicles of the marrow of bones.* cae
It has been supposed that the adipose tissue
receives nervous filaments; and Mascagnicon-
ceives he has demonstrated its lymphatics. Both
points, however, are so problematical, that of
neither of these tissues is the distribution known.
The substance contained in these vesicles is
entirely inorganic. Always solid in the dead
body, it has been represented as being fluid
during life, by Winslow, Haller, Portal, Bichat,
and most authors on anatomy. The last writer,
indeed, states that under the skin it is more
consistent, and that in various living animals
he never found it so fluid as is represented.
The truth is that in the human body, and in
most mammiferous animals during life, the fat
is neither fluid nor semifluid. It is simply
soft, yielding, and compressible, with a slight
degree of transparency, or rather translucence.
This is easily established by observing it durmg
incisions through the adipose membrane, either
in the human body or in the lower animals.
The internal or sebaceous fat, however, espe-
cially that interposed between the fat of the
serous membranes, is much more consistent and |
solid. The reason of these differences will be
understood from what is now to be stated re-
garding the proximate principles of animal fat.
The microscopical and atomical structure of
fat has recently formed the subject of investi-
gation by M. Raspail.t By placing a portion
of lacerated fat upon a sieve, with an earthen
vessel below it, and directing upon it a stream
of water, numerous amylaceous granules are de-
tached and pass through the sieve, and after
falling to the bottom of the water afterwards
rise to the surface, in the form of a crystalline
powder, as white as snow. When these par-
ticles are collected by scumming, and dried,
they form a starchy powder, though soft and
somewhat oleaginous to the touch, and which
does not reflect the light in a manner so cry-
stalline as an amylaceous deposit does.
According to M. Raspail, when examined
microscopically, these granules present forms
and dimensions varying in different animals,
in the same animal and even in animals of dif-
ferent ages, but in all clearly resembling grains —
of fecula. In the human.body these particles —
are polyhedral and not susceptible of isolation. —
As they are more fluid also than in other
animals, it is necessary to immerse the portion —
subjected to examination in nitric acid or
liquor potass@, either of which has the effect
of consolidating the inclosed or central portio

* De Ossium Medulla, Lips. 1758.
+ Repertoire Générale d’Anat. 1827.

ADIPOSE TISSUE.

of each granule, and disintegrating the granules
by the contraction of chemical agency. The
borders of these granules appear by refracted
light a little fringed—an effect which M. Ras-
pail attributes to the corrosive action of the
nitric acid.
When magnified to 100 diameters, they ap~
pear like irregular hexaedral or pentaedral
odies, from two to four lines in diameter, and
all accurately fitted or conjoined to each other.
The actual diameter of these granules in the
adult human subject varies according to Ras-
il from .00117 to .00562 of an English inch.
n youth and infancy they are stated to be still
smaller,
The chief point to bear in remembrance is
_ that the adipose tissue consists of two distinct
parts, one a vital organic and secreting part,
the other an inorganic and secreted product,
__ which is void of vital principle. The chemical
constitution of fat has been investigated by
Chevreul, Braconnot, and more recently by
M. Raspail. According to the researches of
M. Chevreul fat consists essentially of two
proximate principles, stearine (creae, sebum,
sapo, ) and elaine, (erasov, oleum.) ;The former
is asolid substance, colourless, tasteless, and
_ almost inodorous, soluble in alcohol, and pre-
serving its solidity at a temperature of 176°
_ Fahrenheit. Elaine, on the contrary, though
colourless, or at most of a yellow tint, and
_ lighter than water, is fluid at a temperature of
_ from 63° to 65° Fahrenheit, and is greatly
more soluble in alcohol. To the presence of
_ Stearine in a large proportion, the intra-serous
_ sebaceous fat owes its solidity and firmness;
whereas the elasticity and softness of the sub-
- cutaneous adipose tissue, and the marrow,
_ depend upon the predominance of elaine.
It is farther important to attend to the ele-
_ mentary composition of fat. Each variety of
fat consists of carbon, hydrogen, and oxygen ;
and a few, as hog’s lard, blubber, nut oil, and
almond oil, contain a small trace of azote.
The proportion of the carbon is greatest and
_ varies in general from 7-10ths to 4-5ths of the
whole. The proportion of hydrogen varies
from 1-10th to 1-5th. That of oxygen varies
tom four or five parts in the hundred to
12 and 13. It appears, therefore, that fat and
each of its constituent principles are a highly
carbonaceous animal substance.
__ Little doubt can be entertained that animal
fat is the result of a process of secretion. But
it is no easy matter to determine the mode in
which this is effected. Previous to the time
of Malpighi it was a very general opinion that
the blood exuding from the vessels was con-
verted into adipose matter. This fancy was
refuted by Malpighi, who, departing, however,
from strict observation, imagined a set of ducts,
(ductus adiposi_) issuing from glands, in which
1e conceived the fat to be elaborated and pre-
2d. ‘To this fancy he appears to have been
led by his study of the lymphatic glands, and
Inability to org sn how the process of
secretion could be accomplished by arteries
_ only. The doctrine, though embraced by
Perrault, Collins, and Hartsoecher, was over-

A

59

thrown by the strong arguments which Ruysch
deduced from his injections; and Malpighi
afterwards acknowledged its weakness and re-
nounced it. In short, neither the glands nor
the ducts of the adipose membrane have ever
been seen, unless we admit the testimony of
the Members of the Parisian Academy, who
state that they saw them in the civet cat, and
to this we must oppose the fact that Morgagni,
by anatomical evidence, disproved their ex-
istence. Winslow, though willing to adopt the
notion of Malpighi, admits, nevertheless, that
the particular organ, by which the fat is sepa-
rated from the blood, is unknown. Haller,
on the contrary, aware of the permeability of
the arteries, and inferring from the phenomena
of injections either of watery liquors or melted
tallow, their direct communication with the
cells of the adipose tissue, and trusting to the
testimony of Malpighi, Ruysch, Glisson, and
Morgagni, that fat exists in the arterial blood,
saw no difficulty in the doctrine of secretion,
or rather of a process of separation ; and upon
much the same grounds is this opinion adopted
by Portal. Bichat, again, contends that no fat
can be recognized in the arterial blood, and
justly adduces the fact, that none can be dis-
tinguished in blood drawn from the temporal
artery. To the accuracy of this fact I can
bear direct testimony, having repeatedly ex-
amined with the view of recognizing the buffy
coat, and detecting oily particles, blood, which
I had drawn from this vessel,—the latter sub-
stance invariably without success. In wounds
in the human body during life, and living
animals, oily particles may be seen floating on
the surface of the blood; but these, it may be
said, proceed from the division of the adipose
vesicles; and hence it has been inferred that
the arterial blood contains no adipose or olea-
ginous matter.

It may be doubted, however, whether facts
of this kind are adequate to prove whether
adipose or oily matter does not naturally exist
in the blood, and both from the experiments
of Chevreul, and those of Lecanu and Boudet
it appears that small quantities of adipose or
puriloid matter may be obtained from this
fluid. M. Chevreul, for example, shows that
fatty matter may be obtained from the fibrine
of arterial blood ; and from a series of elabo-
rate and accurate experiments, estimates the
quantity of fatty matter in fibrine at from four
to five per cent.* Lecanu and Boudet have
also recently shown that crystals of pearly-
coloured matter having the characters of an
adipose substance exist in, and may be ob-
tained in small proportion from the serum of
the blood.+ These inferences apply, according
to the authors, to blood in its healthy state.

In certain states of the system the blood
drawn from the veins has presented serum of
an opaque or milky appearance, and which
has been proved to depend on the presence of
adipose or oleaginous matter. Thus, indepen-
dent of opaque or milky serum noticed by

* Journal de Physiol. tom. iv. Be 119.
+ Journal de Pharmacie, 1830-33,

60

Schenke, Tulpius, Morgagni, and others,
Hewson and several cotemporary observers
remarked instances of opacity and milkiness
of the serum of the blood, and from ocular
inspection as well as experiment and obser-
vation, inferred that these appearances arose
from the presence of oil in the blood or its
serum. Soon after Dr. Gregory, in his Con-
spectus, or View of the Institutions of Medicine,
was led to infer apparently from the fact stated
by Hewson, that in persons in whom the
serum was opaque or milky, this depends on
the presence of fat which is undergoing ab-
sorption, or resumption into the system. This
representation, however, was entirely conjec-
tural; and no direct proof of the fact that oil
does exist in certain states in the venous blood
was given till Dr. Traill, in 1821 and 1823,
furnished accurate chemical evidence on the
point. The inferences of Dr. Traill have been
since confirmed by the experiments of Dr.
Christison, who found that milky serum con-
tains oleaginous or adipose matter, consisting of
the two adipose principles elaine and stearine.*

The general conclusions, therefore, that may
be deduced from the facts: now stated are that
in the healthy state adipose matter in small
proportion exists in the fibrine of the blood,
and in a still smaller portion in the serum ;
and that in certain morbid conditions of the
system, in which there is any process of mis-
nutrition or paratrophia, oily matter in con-
siderable quantity may be found in the blood,
either in consequence of absorption or non-
deposition.

To account, however, for the secretion of
adipose matter, it is not absolutely requisite to
prove that oleaginous or adipose matter exists
in the circulating fluid. Even were it ascer-
tained that oil or adipose matter does not exist,
or cannot be detected in any of the elements
of healthy blood, the fact would not form a
stronger argument against its formation from
that fluid, than in the case of several other
principles which enter into the composition
of the animal tissues, and which nevertheless
do not exist in the blood. Thus neither gela-
tine, which exists abundantly in skin, tendon,
cartilage, ligament, and bone,—ncr osmazome,
which is found in muscle, are contained in
healthy blood. But we know that the chemical
element of these substances exist in the blood,
and we farther know that gelatine consists very
nearly of the same chemical elements as albu-
men; and we must infer, therefore, that it is
the faculty of the living tissues or vessels to
arrange these elements in that manner and
proportion in which they may constitute re-
spectively gelatine and osmazome. The same
reasoning may be applied to explain the for-
‘mation of fat in the adipose tissue. Its ele-
ments already exist in the blood, and the living
agency of the tissue seems all] that is requisite
to effect its deposition. Its composition and
history would also show that it is a secreted
product which consists of superfluous chemical

* Edin. Med. and Surg. Journal, vol. xxxiii.
Pp: 274. :

ADIPOSE TISSUE.

elements not required in the formation of 1
albuminous and gelatinous tissues. M
On this subject the interesting experiment
of Berard* and Dobereinert may, perhaps,
nish some intelligible means of illustration,
The former chemist found that by mixing one _
measure of carbonic acid, ten measures of —
carburetted hydrogen, and twenty of ao. F
and transmitting the mixture through a red-hot
tube, he procured artificially several white —
crystals which were insoluble in water, soluble _
in alcohol, and fusible by heat into an oily —
fluid. The latter chemist prepared a similar —
substance from a mixture of coal-gas and aque-
ous vapour. \ =
It may therefore be inferred that while ani-
mal fat is chiefly a combination of bicarbonated
hydrogen with oxygen, or, in other words, a
highly carburetted hydrate of oxygen, and con- —
tains either little or no azote, it is the animal
substance which makes the nearest approach
in chemical constitution to the vegetable prin-
ciples. So close, indeed, is this approxima-
tion that Raspail thinks it may be in this re-
pect compared with starch; and as the different
forms of fecula are prepared by the vegetable
tissues for the nutritious stores of the vegetable
during the process of development, he ob-
serves that, in like manner, fat is deposited
whenever the nutritious function is in excess
in the animal organs.
It was a singular fancy of Fourecroy that
the deposition of fat in animal bodies was in-
tended as a sort of vent for the superfluous
and unnecessary proportion of hydrogen, since
the idea is at variance with chemical facts; and
it is not less singular that such a hypothesis
should receive any countenance from Blumen-
bach. Carbon is the principle which predo-
minates most largely in fat; and if any atten-
tion is to be given to such views, the adipose
tissue ought to be regarded as the outlet for
superfluous carbonaceous matter, or at least
carbonaceous matter in a much larger pro-—
portion than hydrogen and oxygen. The pro-
per physiological view, however, of this ques= —
tion appears to be,—+that as the tissues of the ~
animal body consist chiefly of carbon, hy- —
drogen, oxygen, and azote united in variable ~
proportions, and as most of these tissues either —
contain or seem to require azote, the adipose
appears to be destined to receive whatever
carbon, hydrogen, and oxygen, are not re-—
quired to be united with the azote, in the forma-_
tion of the albuminous, the gelatinous, or the
albumino-gelatinous tissues.
On the mechanism of the deposition of fat
we possess no exact information. But various
facts may tend to throw some light on the ei
cumstances under which it takes place, @
the history of the state of the adipose tissue
different periods of life is instructive. ,
In the foetus the adipose tissue contains
sort of whitish, solid, granular matter, wh
resembles adipocere rather than genuine 1

‘
a

+ Zur Pneumatischen Phyt

* Ann. de Chimie 1817 3a Vv. . 290. “ i:
‘hen Bhytochemie, 8vo. Je
1822 Od ae

ADIPOSE TISSUE.

Thus it is less oleaginous, and more brittle
and friable than true fat. In the infant this
layer continues the same in quantity, but a little
more oleaginous, till the period at which the
individual begins to exert the muscles of loco-
motion. The fat then rapidly diminishes in
quantity, and after the child has begun to
walk and run, the fat has almost entirely dis-
appeared from most parts of the adipose tissue,
except the orbits, cheeks, neck, buttocks and

regions it is much less abundant and much
more consistent.

The marrow presents similar changes. The
bones of the fetus are void of a distinct me-
dullary canal, and present merely a reddish,
homogeneous, vascular ‘pulp, somewhat con-
sistent, but presenting soft compressible por-
tions. This state continues some time after
birth. As the individual passes from infancy
_ to childhood, the interior of the bone is formed
_ into cancelli, adipose or oleaginous matter is
deposited in the intra-osseous tissue within
the cancelli, and as the vessels of the medullary
Membrane gradually mould the medullary
canal, this oleaginous matter is most abun-
dantly deposited in the interior of the cylin-
_ drical bones. The marrow, however, is much
less oleaginous, and more like a pulpy paste
than it is in the adult.

__ During the periods of boyhood and youth
_ fat continues very sparing in the adipose tissue,
and especially in the male sex. After puberty,
_ however, it becomes more abundant, especially
in females. After this period the deposition
_of fat depends more or less on the habits of
the individual, as to eating and drinking and
real exertion. In general the deposition
of fat becomes more copious and general after
the age of forty or forty-two than previously.
___ From these several facts it appears to result
that fat is to be regarded as a secretion by the
_ Capillary vessels of the adipose tissue from the
‘blood, and that the tissue and its vessels are
' to be distinguished from the fat or the matter
= ed in the relation of vital agents and
| organic products. Upon the whole the idea
of Haller as modified by Mascagni regarding
the origin of the fat appears to be the most
probable, viz. that, while the arteries secrete
in imperfectly formed oily fluid, the thinner
varts are absorbed either by lymphatics or by
ve and the residue is left ina more con-
istent and solid form.
I think, in conclusion, that, taking all the
circumstances already stated into consideration,
‘it may be inferred that adipose matter, or its
tituent elements exist in the blood, chiefly
plementary elements of the albuminous,
latinous, Osmazomatous, or gelatino-albu-
unous principles employed in the nutrition of
le several tissues; and that, as the —
‘drogen, oxygen, and azote are emplo in
formation of the latter tissues, ‘the great
ess of carbon, and the smaller excess of hy-
rogen and oxygen, not employed in the for-
mation of these tissues are arranged by the
apillaries in such proportions as to form adi-
se matter; and that this adipose matter,

oe.
eon
44, .

yy

the flexures of the joints; but even in these -

’ 61

though fluid, when first formed, becomes more
consistent and fixed after deposition in its
appropriate tissues.

The pathological conditions of the adipose
tissue.

1. Inflammation.—From various facts, and
especially, observing the phenomena of certain
cases of what have been denominated diffuse
inflammation of the cellular membrane, I for-
merly inferred that the peculiar phenomena of
certain intense and malignant forms of this
disorder, depend on inflammation not of the
cellular membrane, but of the adipose tissue.
This conjecture I have since had opportunities
of completely verifying as to certain, if not the
majority of cases of diffuse inflammation.

a. In cases of diffuse inflammation affecting
the arm, the inflammation has spread along
the adipose membrane, producing sero-puru-
lent suppuration and sloughs of the adipose
tissue. In cases of inflammation at the verge
of the anus, the disease spreads along in the
same manner, and affects, almost exclusively,
the adipose tissue around the anus and rectum,
and along the glut@i muscles. It is in the
same manner that the adipose cushion, with
which the bloodvessels are surrounded, is oc-
casionally the seat of a species of bad inflam-
matory action terminating in fetid and sloughy
suppuration.

That these forms of diffuse inflammation
truly depend on inflammation of the adipose
membrane, I must further maintain, from the
fact that the disease occurs not only in the ex-
ternal adipose cushion, but in the internal or
sebaceous fat. I have seen an example of in-
flammation in the adipose cushion surrounding
the left kidney, in which the whole of this
substance was converted into an ash-coloured,
fetid, semifluid pulp, mixed with shreddy fila-
ments, and in which this suppurative slough-
ing process had opened a passage from the fat
of the left kidney into the interior of the trans-
verse arch of the colon. The instance of in-
flammation and subsequent mortification of the
adipose membrane surrounding both kidneys,
detailed by Dr. Thomas Turner, in the fourth
volume of the Transactions of the College of
Physicians in London, is an example of thesame
species of disease. In the case witnessed by my-
self, the disease gave rise to the usual symptoms
said to attend diffuse inflammation. Though
no great degree of pain was felt, the pulse was
quick and small, the tongue brown and dry,
the countenance dingy and lurid, and the eyes’:
heavy, the bowels difficult to be affected by
medicine, the urine scanty and high-coloured,
and at length suppressed; and the patient,
after muttering delirium and typhomania on the
second day of the attack, with subsultus tendi-
num, passed into a comatose state, which ter-
minated on the fourth day in death.

b. This doctrine further does not rest upon
evidence deduced from the mere symptomatic
characters of the disorder. In fatal instances
of diffuse inflammation, we find the adipose
membrane not only partially mortified and’
suppurated, but that part of it adjoining to the
skin and to the bloodvessels very much loaded,

62

with injected vessels containing dark-coloured
blood.

c. It is chiefly in the corpulent, either by
habit or by age, that this disease assumes its
most exquisite, intense, and unmanageable
forms. In persons of this description, who it
is matter of common observation are generally
not only plethoric but bloated, and liable to
imperfect circulation, and disorders of the cir-
culation and secretions generally, and in whom
very slight causes often induce serious disor-
ders, the adipose tissue appears to lose a great
proportion of the small degree of vital energy
which it possesses, and the more abundant its
secreted product is, the less active are its vessels
and the inherent properties of the membrane.
In consequence of this greatly impaired energy,
slight causes, as cold, injury, punctures, &c.
produce suddenly a complete loss of circula-
tion and action in the tissue; for it is not in-
creased but diminished action; and this im-
paired energy continues, until the natural func-
tions of the tissue become extinct. It is thus
that the secreted or inorganic matter of the
adipose tissue becomes, as it were, a cause of
strangulation of the tissue itself, or at least
leads so directly to suppress the energies of its
organic part, that it is incapable of resisting
morbific agents of ordinary power, and hence
the organic part either may be smitten with
immediate death or is very easily made to
assume a very low and imperfect form of mor-
bid action, which speedily terminates in death.

On this subject it is further proper to ob-
serve that Mr. Bromfield, surgeon to St.
George’s Hospital, who sixty years ago main-
tained the distinct characters and situation of
the adipose membrane from the cellular, taught
also that the former was liable to inflammation,
but erroneously imagined that this inflamma-
tion was of the circumscribed kind only.*

2. Hemorrhage.—Effusion of blood into the
adipose tissue is not very common. It is ob-
served in the same circumstances nearly in
which it occurs in the filamentous tissue. Thus
it has been seen in land and sea-scurvy. Hux-
ham observed it in fevers with petechial erup-
tions. And Cleghorn states that one of the
appearances after death in the continuous and
malignant tertians of Minorca was extravasa-
tion of blood in the form of black patches in
the adipose layer of the mesentery, omentum,
and colon.

3. Excessive deposition.—In certain subjects,
and in peculiar circumstances, the quantity de-
posited is enormous. The average weight of
the human subject at a medium size is about
160 pounds, or between eleven and twelve
stones. Yet instances are on record of its
attaining, by deposition of fat in the adipose
membrane, the extraordinary weight of 510 and
600 pounds, or from thirty-five to forty stones.
Cheyne mentions a case in which the weight
was 448 pounds, equal to thirty-two stones.
In the Philosophical Transactions are recorded
two cases of persons so corpulent, that one
weighed 480 pounds and another 500 pounds.

* Chirurgical Observations, vol. i. p. 94,

ADIPOSE TISSUE.

And the Breslau Collections contain cases in
which the human body weighed 580 and 600°
pounds. )

In females and in eunuchs it is more abun-
dant than in males; in females deprived of the —
ovaries it is more abundant than in those pos-
sessed of these organs; and it is well known
that sterility is frequent among the corpulent of
both sexes. In some circumstances this accu-
mulation may be so great as to constitute dis-
ease, (polysarcia adiposa of several nosolo-
gists); and in other circumstances the deposi-
tion of fat is a means which the secreting
system seems to employ to relieve fulness and
tension of the vessels, and if not to cure, at
least to obviate morbid states of the circula-
tion. (Parry.) Accumulations of fat are said
to take place in some animals in a few hours
in certain states of the atmosphere. During
a fog of twenty-four hours continuanee, thrushes,
wheat-ears, ortolans, and red-breasts are report-
ed to become so fat that they are unable to fly
from the sportsman. (Bichat.)

4. Extreme diminution.—The diminution or
disappearance of fat is much more frequent
than its extraordinary abundance. This dimi-
nution is said to depend on one or other of the
following causes. 1st. Long abstinence, as in
fasting, and the periodical sleep of dormant
animals ; 2d, organic diseases, as consumption,
cancer, disease of the liver, of the heart, ulce-
ration of the intestines, &c.; 3d, purulent col-
lections or secretions; 4th, leucophlegmatie
and dropsical states; 5th, gloomy and melan-
choly thoughts or passions ; 6th, long and un-
interrupted effort of the intellectual powers ;
7th, preternatural increase of the natural evacu-
ations, as in cholera, diarrhoea, diabetes, &c.
mucous discharges, especially from the pulmo-
nary and intestinal membranes, as in chronic _
catarrh, inflammation of the intestines, and —
dysentery ; 8th, long and intense heat, whether
natural, as during hot summers, or artificial, as
in furnaces, hot-houses, &e.; 9th, running,
riding, and every species of fatiguing exercise
long-continued, as is exemplied in the case of
grooms at Newmarket, Doncaster, &c.; 10th,
states of long disease, not organic; 11th, night-
watching and want of sleep in general; 12th,
immoderate use of spirituous liquors; 13th,
habit of eating bitter and spiced or acid
aliments.

Yet even in these states the fat of the animal
body is seldom entirely wasted. In several
organic diseases, in which great emaciation —
takes place, a considerable quantity of fat is
always found in the orbits behind the eyeball,
round the substance of the heart, around the
kidneys, in the colon, and in the mesentery
and omentum. Thus one or both lun
be extensively occupied by tubercles an
rated portions giving rise to the-usual symptoms
of pulmonary consumption terminating fatally
yet without removing the fat from the subcute
neous layer of the chest and belly; and i
various organic affections of the brain esp
cially, a considerable quantity of fat is found,
not only in the subcutaneous layer, but at the
outer surface of the serous membranes. ”

ADIPOSE TISSUE.

_ According to the observations of William
Tlunter, anasarcous dropsy is the only disease
in which the fat of the adipose membrane is
entirely consumed. ‘ This disorder, when in-
veterate, has that effect in such a degree, that
we find the heart or mesentery in such subjects
as free from fat as in the youngest children.”
This, however, is in some degree denied by
Bichat, who contends that it is not uncommon
to find much subcutaneous fat in subjects
greatly infiltrated.* It is obvious that much
will depend on the stage of the disease. It
cannot expected that the moment serous
infiltration appears in the filamentous tissue,
all the fat should be at once removed from
the adipose. The process of absorption is
gradual as is that of deposition; and the infe-
rence of Hunter may be regarded as nearly
exact in reference to long-continued, or what
he terms inveterate dropsy. It is certain, that
while it is very difficult to deprive the bones of
ordinary subjects of oil, those of dropsical sub-
jects are the only ones which it is possible to
obtain free from this substance.

In certain diseases, especially those the ter-
mination of which is attended with serous
effusion into the cavities of the serous mem-
brane, the fat is partly absorbed or may be
converted into a sort of sero-gelatinous fluid.
In chronic dysentery, for example, the subcu-
taneous fat and that of the heart and omentum,
in a great measure disappear, while in their
place we find effused an orange-yellow coloured
sero-albuminous fluid, of a jelly-like aspect,
_ which coagulateson the application of heat or the
_ addition of re-agents. In the bodies of those,
also, cut off by scirrhous disorganization or
cancerous ulceration, the greater part of the
fat is in like manner absorbed, and in its place
appears a dirty orange-yellow coloured sero-
albuminous fluid.

The removal of the fat from its containing
membrane is effected by the process of absorp-
| yon the agents of which are supposed by
- William Hunter, Portal, Bichat, and Mascagni,
| tobe the lympathics. According to the results
| of the experiments of Magendie, Mayer, Tiede-
Mann and Gmelin, Segalas and others, it must,
‘im some measure at least, be ascribed to the in-
fluence of minute veins. It isa point of some
interest to know in what form it is absorbed,
whether as oily matter, or after undergoing a
process of decomposition The observation of
Dr. Traill, above quoted, would lead to the
former view ; but it is not easy to conceive that
this should be uniform. We want, in short,
_ correct facts on the point at issue.
_ 5. Adipose sarcoma.—This consists in an un-
usual deposition of firm fatty matter in cells,
the component fibres of which are sufficiently
m to give it consistence. The tumour, which
generally globular, is always surrounded by
hin capsule, formed by the condensation of
ihe contiguous filamentous tissue. The tumour
S supplied pi a few bloodvessels, which pro-
eed from the capsule, but which form so
ender an attachment that they are readily

‘

* Anat. Gén. vol. i. p. 57.

63

broken, and the tumour is easily scooped from
its seat. This sort of tumour occurs almost
invariably in the adipose membrane, and seems
to consist in a local hypertrophy of the part in
which it is found. It may have a broad basis,
but is often pendulous, or attached by a narrow
neck or stalk. It is the most common form

of sarcomatous tumour, and may occur in any

oe of the body in which there is adipose mem-
rane, but is chiefly found on the front and
back of the trunk, and not unfrequently on two
places at the same time.

6. Steatoma.—In adipose sarcoma the adi-
pose matter is deposited ‘in cells, and the
tumour derives a degree of firmness from the
fibres with which it is thus traversed in every
direction. In other instances, however, the
adipose matter is deposited in a mass in the
cavity of a spherical or spheroidal cyst, formed
in the filamentous or adipose tissue; and the
tumour is soft and compressible, and seems to
contain fluid or semifluid matter. When cut
open it is found to contain a soft semifluid
matter of the consistence of honey, but of oily
or adipose properties. In such circumstances
the inner surface of the cyst, or at least the
vessels of this surface, are the agents which
secrete the fatty matter. This tumour may
occur either in the filamentous or the adipose
tissue, but is to be regarded as an example of
local deposition of adipose matter. It may
appear in any region of the filamentous tissue,
but is most frequent about that of the head and
face. Small steatoms are not unfrequent in the
eyelids and in the scalp. Larger ones are more
frequent about the neck.

7. Lipoma.—This name was first applied
by Littré to a wen or cyst, filled with soft
matter, possessing the usual properties of ani-
mal fat. The matter of steatom, according to
this surgeon, is either not or imperfectly in-
flammable, by reason of its degeneration or
commixture with some other animal secretion.
The propriety of this distinction has been de-
nied by Louis and others, who maintain that
these tumours differ in nothing, unless per-
haps in degree. It has been favoured, never-
theless, by Morgagni, and adopted by Plenck,
Desault, Bichat, and various foreign surgeons,
and is defended by Boyer, who represents the
steatom as differing from /ipoma in the matter
being white, firm, and changed from its origi-
nal character, and in possessing the tendency
to degenerate into cancer. Plenck had previ-
ously distinguished the lipoma by its being
destitute of a cyst, a circumstance not required
by Littré.

Though thus admitted to differ, the anato-
mical character, as given by Morgagni, and
confirmed by Boyer, is in both nearly the
same: a cyst, containing unchanged fat, or
granular adipose matter, in cells formed by the
original fibres of the adipose membrane, ac-
cording to Morgagni, or those of the filamen-
tous tissue, according to Boyer. At the base
or stalk, in the case of pendulous steatom, the
cells are compressed, but loose in the body of
the tumour.

This description, with the alleged cancerous

64

tendency, accords more with the characters of
the adipose sarcoma than those of the genuine
wen. Personal examination enables me to say,
that, in the case of small steatoms of the scalp,
eyelids, face, &c. no fibres of this kind are re-
cognized; and to such, if any distinction be
adopted, the name of dipoma should be con-
fined. In the case of such larger steatoms as
I have seen in other regions of the body, though
the contents are firmly connected together, and
some filamentous threads may be seen here
and there, or the tumour may even be separa-
ble into masses, I have not been able to trace
the distinct arrangement of cells, mentioned by
Morgagni and Boyer. Weidmann mentions,
that in one case the matter of steatom was a
sort of liquefied fat, and in another firm and
dense, and not divided into lobes or cells.
The other forms of encysted tumours, distin-
guished by the names of atheroma, (aOnewpa,
pulticula,ab abaga, pultis genus, ) and meliceris
(uerruness, mel and cera, honey wax,) are to be
viewed rather as varieties of the steatom than
as generically different. The substance con-
tained may differ in consistence, but is nearly
the same in essential qualities.

8. Melanosis—The adipose membrane is a
frequent seat of this singular deposition. The
black or melanose matter is found in the sub-
cutaneous adipose membrane, and the subja-
cent cellular tissue of the chest and belly ; it
is not uncommon in the fat of the orbit; it is
very commonly seen in the adipose cushion on
the forepart of the vertebral column, on that sur-
rounding the kidneys, and in the fat of the anus
and rectum; it is found in the anterior and
posterior mediastinum ; and it is found be-
tween the folds of the mesentery, of the meso-
colon, and of the omentum. It is also found
in the substance of the marrow of bones; and,
perhaps, in most cases in which the osseous
system appears to be stained with the melanose
deposite, the dark matter may be traced to the
medullary particles, the situation of which it is
found accurately to occupy.

In all these situations it appears in various
degrees of perfection, and in different forms.
It may be disseminated in black or inky spots,
through the adipose membrane; it may be ac-
cumulated in spherical or spheroidal masses of
various size and shape; or it may be found in
the form of brown or ebon-coloured fluid or
semifluid, enclosed in a cyst fermed of the
contiguous tissue, more or less.condensed.

The melanose matter is entirely destitute of
organization, and is to be regarded as the result
of a peculiar secretion. No vessels have been
traced into it; and when bodies affected with
this deposite are minutely injected, the vessels
can be traced no farther than the enveloping
cyst. (Breschet.) It is also to be noticed that
itis never deposited exactly in the site of orga-
nic fibres, but always between them, and very
generally in the precise situation of the adipose
particles. These several circumstances show
that the melanose disease consists not in a de-
generation or conversion into another substance,
but in the deposition of a new form of matter
in the manner of a secretion.

AGE.

Tn what form the melanose substance is frst
deposited we have few accurate facts to enab =

us to form a judgment. Laennec is of op
afterwards becomes fluid. The former he con=

that it is first deposited in a solid form,

siders the stage of crudity, the latter that . ae
softening (ramollisement.) Several facts, how-
ever, would lead to the conclusion, that when
first deposited it was fluid, and afterwards ac-
quired consistence. Thus in several dissec-
tions performed by Drs. Cullen and Carswell,*
the matter of the small tumours, which are
supposed to be of short duration, were found
to be softest, and sometimes as fluid as cream.

In like manner, in a case recorded by M. —
Chomel, in which the disease was found in the
liver in the shape of large cysts, the melanose
matter was more fluid in the centre than in the
circumference of the cysts. Upon the whole,

if the melanose deposite be, as is supposed, an
inorganic secretion, the idea of its being poured
forth from the vessels at first in a fluid or semi-
fluid state is most probable, and most consis-
tent with the usual phenomena and laws of
animal processes.

BIBLLOGRAPHY.—Malpighi, de omento, pingue-
dine, et adiposis ductibus. Op. Omn, fol. Lond.
1686. C. A. De Bergen, Programma de Mem-
brand Cellulosa in Haller Disp. Anat. Select.
tom. iii. Haller, Elementa Physiologie, lib. i.
sect. 4. W. Hunter, On Cellular Memb. in Med.
Obs. and Inquiries, v.ii. p. 26. Bachiene, Diss. de
Adipe humano, 4to. Ultraj. 1774. Janssen, Pin-
guedinis Animalis consideratio. 8vo. L. B. 1784.
Redhead, Diss. de Adipe. 8vo. Edinb. 1789. Vogel,
Diss. sur la graisse. 8vo, Paris, 1806. Allmer,
Diss. In. De pinguedine animali, 4to. Jenw 1823.
Heusinger, System der Histologie. 8vo, Gruetz-
macher, De Medulla Ossium. (Rec. in Haller. Disp,
Anat. vol. vi.) Lorry, Sur la graisse (Mém, Soe.
R. de Med. 1779. Kiihn, De pinguedine, 4to,. Lips.
1825. Beclurd, Anatomie Générale, p. 1
Chevreul, Recherches Chimiques sur les corps
gras d’origin animale, 8vo. Paris, 1823; and Ma-
gendie’s Journ. de Phys. tom. iv. Raspail, in
Repertoire Gén,. d’Anat. tom. iii. et iv. et Nouvean
Systéme de Chimie Organique, or Henderson’s

i
1
;

Translation,
( David Craigie.)
AGE.— (Lat. ctas. Gr. tAmea. Germ.
Aller. Fr. age. Ital. etd.) This word, in its

most extended sense, may express any period of
duration. In reference to the human body it
is used to denote either the whole time occu-
pied by this system in passing through its
several stages from birth to decay, or, in a-
more limited signification, that particular por-_
tion of existence commonly designated old —
age. It is in the former of these meanings
that we employ the prefix to the following arti-
cle; in other words, we propose to give an
account of the organic and functional changes
which the human system undergoes, from th
commencement of extra-uterine life to the
period of its dissolution by natural decay.
The term of human existence has been 1
riously divided, and in many instances w
a view to adapt its divisions to certa
fanciful notions respecting the power of nun

* Trans. Med. Chir. Soc. Edinb. vol. i. p. 264.

AGE.

bers ; but the only rational principle on which
we can distinguish certain definite periods,
must be that of observing alterations in the
condition of the whole body or of its several
organs, and the correspondence which they
bear to particular epochs. The old Aristo-
telian division of human life into three stages,
growth, maturity, and decline, is founded on
this principle ; for, viewing man as a whole,
the conditions in which he is an imperfect, a
complete, or a declining member of his species,
are well marked. But these conditions are
capable of subdivision according to the changes
which particular organs have undergone; in
other words, man, in the progress of his per-
Jectionnement, makes certain acquisitions in his
structures and functions, and in his decline
suffers certain losses and impairments; the
more striking of these additions to, or sub-
tractions from his resources, suggest the well-
known division of existence into infancy, boy-
hood, puberty or adolescence, manhood, old
age, and decrepitude. It is not our intention
to discuss the subject of age by describing the
characteristics of the stages last enumerated ;
we think it better to take a view of the general
revolutions which transpire in the human
economy during growth, maturity, and decline,
and under each of these heads to mention the
changes which particular organs undergo in the
course of time, without limiting ourselves to
distinct stages, the determination of which must
_ be, to a certain extent, arbitrary.
The consideration of the alterations which
_ take place in the body during its progress from
infancy to manhood might very properly be
_ preceded by some remarks on those ultimate
processes which are essential to growth, viz.—
butrition, secretion and absorption; but, for
‘information upon this interesting subject, the
_ limits prescribed to this article compel us to re-
fer the reader to that upon NUTRITION, in which
the processes alluded to will be viewed in rela-
\ tion not only to the development, but also to
the maintenance, and to the decay of the
tissues.
_ Oncomparing a young with an adult animal
We are at first struck by the difference in bulk ;
ut immediately afterwards our attention is
attracted by the difference in their respective
apabilities of action,—a difference not merely
roportionate to that of size. A closer ex-
umination informs us, that in the infant many of
he parts of the body are absolutely incomplete,
as Organs or instruments, and we proceed to in-
vestigate whether this imperfection holds with
ll the organs or only with some of them; and
' the latter be the case, whether the parts thus
“isting only in a rudimentary state belong to
particular class. Now, the organs and func-
ons of man, in common with those of other
limals, are divided into those which he shares
ith organic beings in general, and those
hich distinguish him as an animal ; the former
ibserving his own independent existence, the
tter his existence in relation to external ob-
cts of his consciousness ; these more or less
ibjected to the control of volition, those re-
ed, under ordinary circumstances, from the

| ‘ VOL. I.

¥
a
a

:”
"1

ri

A
’

65

government of this principle. Hence these two
classes have been variously named organic
and animal, nutritive and relative, automatic
and voluntary ; and, as life is a term employed
to designate the collective functions according
to some physiologists, or the cause of them ac-
cording to others, we have organic life and
animal life, &c.,&c. But the animal functions
are truly supplemental; they could not subsist
but by virtue of the organic; while, on the
other hand, the latter are perfectly capable of
a separate existence, as in the vegetable world,
or in those conditions of animal life in which
its characteristics are all but suspended, such
as profound sleep and apoplexy. Yet, al-
though the functions of relation are thus de-
pendent on those of nutrition, it is evident, at a
moment’s glance, that the latter viewed col-
lectively in an animal structure, would present
an aspect altogether incomplete, and different
from that which we notice in the system of a
vegetable. In the one case they were obviously
intended to act only for themselves and for one
another; in the other they have an ulterior
object to fulfil, but for which they would
not have been called into existence and opera-
tion; this object is the production and support
of the functions that constitute the animal.
If we now look at the new-born infant in con-
trast with the full-grown man, we at once per-
ceive that the essential difference between them
has reference to the life of relations ; in other
words, the immaturity of the former is not de-
termined by the state of the vegetative organs,
which, as organs, are perfect, but by the unde-
veloped conditions of the parts which are to
receive impressions from, and to re-act upon
surrounding objects. Thus, on the one hand,
we observe that the food adapted to the little
being is rapidly converted into chyle, that
the blood, after undergoing its requisite changes,
performs its circuit freely and effectively, and
that the activity of the nutritive, secernent, and
absorbent processes is evidenced by the quick
increase of growth, and by the abundant fluids
contained in the various tissues. But, on
turning to the relative functions, we find the
case altogether reversed ; sensation is dull, faint,
and flitting; voluntary motion scarcely ex-
ceeds the amount necessary for obtaining nutri-
ment from the parent; while the demonstra-
tions of intelligence are the very lowest com-
patible with our belief in the possession of
such a principle by the being in question. An
examination of the organs devoted to these
several actions leads to results in accordance
with what we observe in the functions them-
selves; in the one class the organization is
complete, in the other much remains to be
accomplished. If the apparatus of digestion
be inspected, the parts employed in deglutition,
viz., the tongue, pharynx, and cesophagus, will
be found fully formed; in the stomach the
parts required for accommodating the aliment
during its stay and for mixing certain fluids
with it, are properly developed; no deficiency
is observable in the structure of the liver
and pancreas; and the chyliferous vessels are

pervious, extensile, and perhaps contractile. If
F

66
we proceed to the organs of circulation, similar
conditions are observable. In the heart the seve-
ral cavities, valves, and fibrous arrangements are
duly proportionate to each other, and possess such
qualities of firmness, pliancy, distensibility and
contractility as are required for receiving, expel-
ling, agitating, and keeping in separate compart-
ments the two different kinds of blood ; the
arteries are found resistent enough to hold the
blood within their calibres, and at the same
time elastic enough to adapt themselves to the
varying quantity of their contents, while the
veins are found so organized both as to the
muscularity of their coats, and to the perfection
of their valves, as to be quite capable of con-
veying the fluid back to the heart. Not less
complete is the apparatus of respiration,
whether we regard the development of the
diaphragm, or the elasticity of the thorax, or
the cellular and tubular arrangements in the
lungs and their appendages. For affording the
necessary conditions for the occurrence of those
molecular motions which constitute deposition
and absorption, and upon which secretion also
depends, we find an infinite number of capillary
tubes well formed for supplying the fluids from
which new particles may be taken,and to which
old ones may return, and so disposed as not to
interfere with the action of any supposable
chemical affinities. Ifwe next direct our at-
tention to the organs of the animal functions,
an opposite set of facts will directly meet us.
In the locomotive system, the bones are dis-
covered imperfectly ossified, the muscles de-
ficient in fibrin, and the tendons and ligaments
in firmness and density. Of the organs of
sensation it may be said, in general terms, that
the mechanism employed in the application
of the appropriate stimulus is, for the most part,
incomplete, while a difference is also observa-
ble in certain properties of the nervous sub-
stance.

From this view it might at first be con-
cluded that, in order to trace the changes that
ensue between the commencement of extra-
uterine life and the attainment of maturity, we
have only to look for them in the organs of
the relative life. But the survey that we are
about to take of the changes in question will
show that the other class of organs are by no
means exempt from alteration, although the
changes are not those of development. They
will be found to have reference to degree or
amount of function rather than to capacity.

The external characters of the infant just
eliminated from the uterus at the full period of
gestation are as follows:—the integuments
are thin, tender, and covered with a white
unctuous matter; the nails just reach the ends
of the fingers ; the trunk and limbs are round
and plump; and the articulations are in a
state of flexion. The average weight of the
body is about six or seven pounds; the length
varies from seventeen to twenty-one inches,
sometimes falling short of or exceeding these
limits. The point which lies midway between
the two extremities is at the umbilicus. The
dimensions of the head and of the abdomen
are very large in proportion to the other cavities,

AGE.

and as compared with their own measurements in
after periods of life. The pelvis looks con-
tracted, the thorax flattened at its sides and
prominent in front, and the lower extremities
are less developed than the upper. A line
drawn from the occiput to the chin measures —
five inches and three lines; from the occiput

to the forehead four inches and three lines ;

and from the vertex to the base of the skull
three inches and six lines. The circumference
of the head, taken along the course of the
median line, is from thirteen to fourteen inches ;
but taken horizontally, and passing over the
parietal protuberances, it seldom measures
more than ten or eleven inches. The contrast
between this general aspect and that of a full-
grown man is too obvious to require any repre-
sentation of it here.

The characters of the interior will be best
described and understood by examining ana-
lytically the several apparatuses of the func-
tions. Of the latter the most simple and
primitive is assimilation, consisting of certain
molecular motions which maintain, repair, and
mould the organic tissues. We have already
observed that the requisites for this function
are perfect in the new-born infant; a copious
supply of the fluid from which the textural
particles are to be elaborated, a ready ingress
for this fluid, and a no less ready egress for
that which receives the particles no: longer
required in the process. All that we know
of the mechanism employed is a porous ex-
tensile substance, varying in its chemical con-
stitution according to the nature of the tissue.
Porosity is resolvable into a collection of
infinitely minute tubes, and the degree of
porosity is, therefore, determined by the
number of the tubes ; the extensibility depends
on the composition of the tubes. The tissues
of the infant are soft, they abound in fluids,
and are more capable of imbibition or artificial
injection than at later periods of life; this
being consequently possesses a complete me-
chanism of nutrition. But this mechanism
can be of little utility unless the nutrient
fluid be supplied liberally, and after furnish-
ing the atoms for the formation of the several
textures give place to fresh supplies. These
conditions are afforded by the arteries and
veins.

There is no period of human existence in
which the processes of interstitial growth are
so active as in infancy, whether they be
instanced in the accretion of matter, in the
change of composition, or in the modification
of form. This fact is in harmony with the
state of the capillary system just described,
and it will be found to correspond no less
with the relative construction of the arteries
and veins. The function of the former ¢
these is to convey the blood into the tissue
of the latter to take it away; consequently
in a part where the growth is most energetic
we might, @ priori, expect that the form
would be more numerous, capacious, an
distensible. This is well known to be fl
case from actual observation, partly of th
effects of artificial. injection, and partly ¢

AGE:

the phenomena of disease. An examination
of the textural properties of the two sets of
vessels leads to the same conclusion. Sir
Clifton Wintringham, in his Experimental
Enquiry, fully demonstrated that the venous
coats in the young animal far exceed the
arterial in density, and that, consequently,
they are less subject to distension. When
maturity is attained, the disproportion between
the resistances of these vessels no longer
exists.

However well provided the infant may be
with the mechanical apparatus of pores and
vessels, these can be of no avail unless the
fluid they contain possesses certain chemical

__-—properties. Now the blood in early extra-
uterine life presents the same general characters
as in more advanced periods; but there is yet
wanting a comparative analysis of this fluid
at different ages.* Inferentially we can enter-
tain no doubt that it is fully adapted to the
_ purposes of nutrition, when we consider the
-__ conditions of the chylifactive and respiratory
_ functions, and that, although the differences
__ of its composition in early and in more mature
periods have not been defined by experiment,
they must bear a relation to the different de-
grees of nutrition and secretion. The differ-
ence, however, between the blood of the infant
and that of the aged is perceptible to the
senses, and will be noticed hereafter.
_ Pursuing the channels of the blood to the
heart, we find this organ, as stated above,
complete in its functions. Its volume, how-
ever, is large in proportion to the size of the
body. Its parietes are less firm in texture,
and of a paler colour than they afterwards
become ; but their contractility is more active.
The pulsations are from 120 to 140 in a
minute. The large volume is in harmony
with the quantity of the fluid, the comparative
weakness of its parietes with the small extent to
_ which their impulse requires to be propagated,
_ and with the trifling resistance; and the quick
* Successions of its contractions furnish the fresh
| supplies of the nutriment required by the
_ energy of growth. In the progressive develop-
Ment of this organ we notice that the bulk,
_ although increasing so long as general growth
continues, is proportionately smaller, a cir-
_ cumstance that corresponds with the diminution
of the circulating fluid; the fibres become
‘Stronger and of a deeper hue, so that the
contractions are more capable of propelling
_ the blood through the greater extent which it
Aas now to traverse, or, more strictly speaking,
oi communicating a shock to a greater column;
but the pulsations are slower, agreeably to the
d mini requirements on the part of the

ca actions. We must not omit to ob-
‘Serve that at birth the parietes of the left
ventricle scarcely exceed those of the right in

hickness; but from this period an alteration

__™ De Blainville states, on the authority of
x oy, that in infancy the albumen of the blood
is more abundant, that the fibrin is softer and
‘more gelatinous, and that the phosphates are in

‘smaller proportion than in succeeding periods. Cours
le Physiologie, t. ii, p. 262.

67

commences, and rapidly proceeds until the
thickness of the latter is to that of the former
as 1:4. This change corresponds with the
closure of the foramen ovale, the obliteration
of the ductus arteriosus, and the consequent
execution of the systemic circulation by the
left ventricle only. The relative capacities of
the right and left cavities begin to alter soon
after birth. From tables given by Meckel it
appears that, while at birth the capacity of the
former compared with that of the latter is as
1: 14, at the age of 50 it is nearly 3: 1.*

The lungs at the moment of birth undergo
a more remarkable alteration in their form,
their texture, and their contents, than any
other organ in the system ; but during infancy
and childhood they present no appreciable
change in their organization, although a change
must be inferred from the increase of their
function. In infancy there is a smaller con-
sumption of oxygen; and the power of gene-
rating heat, a function so intimately connected
with respiration, is inferior to that possessed
in later periods. Much light has been thrown
on this subject by the researches of Dr. Ed-
wards; and practical observations of the highest
mportance in the management of infants,
founded upon the facts which he has ascer-
tained, are to be met with in his valuable
work.+ The inspirations and expirations are
more frequent at this early period, although
the chemical actions between the air and the
blood are less considerable. This greater fre-
quency is a necessary accommodation to the
rapidity of the circulation. At puberty there
is a marked development of the organs of
respiration; the volume of the lungs increases
in conformity with the expansion of the thorax;
while the greater determination of the blood
to their vessels is indicated by the deeper hue
of the parenchyma, by the liability to pulmo-
nary hemorrhage, so characteristic of this
period, and perhaps also by certain diseases
which affect the nutrition of these organs.
The corresponding activity of function is indi-
cated by the increased power of calorification,
the energy of muscular motion, and the exalta-
tion of the cerebral actions; functions well
known to have a direct relation with that of
respiration; while the establishment of the
generative faculty appears to own a connexion,
though somewhat more remote, with the pul-
monary development.

We pass from the system which imparts
new properties to the blood to that which
supplies it with nutriment. No imperfection
is discoverable in the apparatus of digestion
in the new-born infant ; every organ is com-
plete as an organ, but passes through va-
rious changes in adaptation on the one hand
to the food that is supplied, and to the mode
of receiving it, and on the other hand to the
demands of the other parts of the body. The
organs employed in conveying and modifying
the chyle, viz. the lacteals and the mesenteric

* Manuel d’Anat, t. ii. p. 284.
+ On the Influence of Physical Agents, &c.
translated by Drs. Hodgkin and vicars
F

68

glands, sre in a state of high development,
‘as indicated both by their size and by their
tendency to disease. The stomach and duo-
denum are fully formed, but the sensibility
of their mucous membrane is adapted only to
the milk of the mother; any other kind of
food has a greater or less tendency to produce
irritation. This membrane is thick, extremely
villous and vascular, and consequently of a
rose-colour.* In young persons it assumes
a milky or satin-like appearance; in the adult
it becomes slightly ash-coloured, especially in
the duodenum and in the commencement of
the ileum ; in the old subject it is more de-
cidedly ashy. Its whitish appearance, according
to Andral,+ is found either in very old persons
or in younger subjects who have died of ma-
rasmus. In the adult the small intestines,
according to Orfila,f bear a proportion of eight
to one as compared with the distance from the
mouth to the anus; in the infant the propor-
tion is no less than twelve to one.§ The large
intestines are longer with respect to the small
intestines in the infant than in the adult; but their
calibre is proportionally smaller. Ascending to
the mouth we might be tempted to say that
there is evidence of incompleteness in the ab-
sence of teeth; but a moment’s consideration
assures us that the organs collected in this part
are all eminently adapted to their function.
The food is already prepared by the mother,
and only needs to be extracted and conveyed
into the pharynx ; actions which are perfectly
achieved by the lips, cheeks, and tongue.
When the period has arrived at which this
food can no longer be furnished with safety
to the mother, and when all the purposes are
accomplished which were intended in this
close connexion between the two beings—
purposes in all probability of a moral as well
as a physical character—the infant is prepared
for a more independent existence by the emer-
gence of teeth. This event generally begins
about the sixth or seventh month by the appear-
ance of the two middle incisors in the lower
jaw; these are followed by the corresponding
teeth in the upper jaw; next are seen the
lateral incisors below and above: the rest
appear in the following order ;—the first molars,
the canines, and the second molars; those of
the lower jaw having generally the priority
of emergence. The milk-teeth, as they are
called, by the end of the seventh year have
given way to the second and permanent series.
For the different characters of the two sets,
the order of their appearance, and other par-
ticulars, we beg to refer the reader to the
article Trers. That the first series should
be only temporary is a necessary provision,
in conformity with the change in the conforma-
tion of the maxillary bones which ensues at
the same time.

We must not leave the alimentary tract with-

* Billard, Traité des Maladies des Enfans, &c.

t Précis d’Anat. Pathol.

$ Legons de Méd. Lég. t. i. p. 62.

§ This statement is at variance with that of
Meckel, who says that the small intestine is much
shorter in the early periods. . Op, cit. t. iii. p. 424.

AGE,

out observing that the fibres of the stomach
and intestines in infancy and childhood are,
like those of the heart and other involuntary
muscles, more irritable than in after life; hence
the contents of these viscera are propelled more
rapidly, and the evacuations are more frequent;
their tissue is also softer, and their colour more
approaching to white. ,

he liver undergoes a great change after
birth both in form and in function. The pecu-
liar circulation of which it formed so important
an organ during foetal life being abolished,
the left lobe which nearly equalled the right
in volume, is diminished to a third of its original
size. But while the umbilical vein and the
canalis venosus are obliterated, the vena porte
is developed, and the bilious secretion becomes
the predominant function. Of the further
changes which this organ experiences, we have
very little knowledge, except that the whole
bulk is greatly lessened, and that the colour of
its parenchyma becomes darker, and that it is
more subject to disease in after periods. Oc-
casionally we meet with instances in which the
fetal proportions of the liver continue through
life (Andral). The bile has not been carefully
examined with reference to particular ages,
but it is known to be less viscid and to contain
a smaller quantity of its peculiar principles
in infancy ; while its greater liability to con-
cretions at more advanced periods indicates an
alteration in its composition. The gall-blad-
der, though small at birth, contains bile, green
in colour and bitter in taste, and soon becomes
enlarged.

The spleen also increases in volume, but
what alteration takes place in the progress
to maturity, in its function, must, of course, be
doubtful until the function itself be better
understood. Probably its enlargement is con-
nected with the distended condition of the
venous system. Of the changes in the pan-
creas and salivary glands, we know little more
than that their texture increases in firmness.
The lacteals, lymphatics, and their respective
ganglions have a very marked development.
It is to be regretted that no observations have
as yet been made upon the composition of the
chyle at different ages. There are doubtless
many alterations corresponding to the varying
activity of the digestive function, and to the
kinds of aliment used at those periods.

So much for the organs and functions which
are concerned in augmenting or modifying the
nutrient matter. Before proceeding to those
of the relative life, we must allude to the
organs of excretion. The kidneys at birth
have not lost the traces of their lobular forma-
tion, but these are soon’ effaced. The weight
of these organs at birth is to that of the whole
body as 1°80; in the adult 1°240. The me-—
dullary portion is more abundant than the corti-
cal in early life. The supra-renal capsules soon be=
gin to shrink from their foetal size. The ureters
are large, and the bladder has a more elongated
form than in after periods; it also occupies a
higher situation above the pelvis. The fune-
tional qualities of these forms are not so well
ascertained as the analogy of their organization

‘
4

AGE.

that of inferior animals. The urine is retained
a shorter time in the bladder ; it is more aqueous
and less impregnated with saline and animal
ingredients oe in after life; there is also a
particular deficiency of urea. Of the intes-
tines we have already spoken; their contents
are copious but less feculent than they after-
wards become. The perspiration affords a si-
milar character to that of the other excrementi-
tious secretions, being more aqueous, less sa-
line, and less odorous. On the whole it may
be said that less activity is indicated in the
egestive than in the ingestive system.

Of the defensive organs, or those which
are exposed to surrounding agents, we may
remark, in general terms, that although fully
adequate to the demands of the infant under

__ the circumstances of his existence, they acquire
__adevelopment proportionate to his growing in-
_ dependence of the care of others. The skin
__ increases in firmness, and the epidermis in thick-
ness ; the sebaceous follicles become larger and
more numerous, and the hair is more abundant.

There is a portion of the nervous system
which we have every reason to consider more
related with the functions which have been just
reviewed, than with those of the animal life, and
which might d@ priori be expected to bear
a corresponding ratio of developement. We
allude to the ganglions; they appear to be
fully formed at birth, but what changes they
undergo between that period and maturity we
do not profess to know. In old age their
tissue is found hardened, shrunken, and of a
greyish colour. (Bichat.)

The changes that we have next to take
notice of are of a totally different character
from the foregoing. They consist not merely
in augmentations of size, correspondently with
the general increment of the body, or in modi-
fications of organs according to the altered
circumstances under which they have to act,
_ but in processes essential to the completeness
_ of certain organs. These are the parts em-
| he in locomotion, voice, sensation, and
_ thought. We shall begin with the osseous
system.

_ Bones are not subservient to locomotion
only; they have, in some parts of the body,
the important office of enclosing and defending
from external injury the more delicate organs of
the system. We shall find, therefore, that in
the young animal, according as they fulfil the
one office or the other, their development will
fer. But whatever be the functions of the
as, they require, for the perfection of that
function, three mechanical properties,—firm-
ness, lightness, and tenacity. ey must not
admit of flexion, and, at the same time, the
snsity of their substance must not render
them cumbrous by weight, or brittle in texture.
To present these three conditions, the organs in
question consist of two principal ingredients,
in animal matter and an earthy matter, most
ntimately interwoven ; the one preventing such
vibrations as would occasion risks of fracture,
the other affording the necessary strength in
supporting weights, and in resisting the divellent
endencies of antagonist muscles. The pro-

69

portion which these parts bear to each other
varies with the ages of the human subject.
Viewed as a part of the system devoted to the
life of relations, bones are used as pillars of
support, as levers in various attitudes and mo-
tions, and as points d’appui to the muscles and
tendons. On examining the constitution of
these portions of the osseous system in the
new-born infant, we find the quantity of cal-
careous salts comparatively small, and even
the animal substance softer than in later pe-
riods, in consequence of the greater ratio of
gelatine. In growth these proportions undergo
a gradual alteration ; the gelatine is diminished,
the cartilage becomes firmer, and both give
way to the deposition of earthy particles: in
the increase of density produced by this de-
sieht consists the process of ossification.

© particularize the incompleteness of the
osseous system would require us to enter upon
the anatomy of almost every bone in the body,
an investigation incompatible with the limits of
this article. Some idea of it may be obtained
from the fact that all the epiphyses of the long
bones, and the greater number of the apophyses
are as yet but cartilaginous; they derive their
ossification, not from an extension of the pro-
cess in the bones to which they are attached,
but from ossific centres within their own
spheres. In the tarsus the only bones in
which ossification has commenced are the as-
tragalus and os calcis. The carpus is entirely
cartilaginous. The os innominatum of the pel-
vis consists of three separate bones ; ossifica-
tion has but just commenced in the descending
ramus of the pubis, and the ascending part of
the ischium ; and the consolidation of the pel-
vis is not complete till after the thirteenth year.
The long bones have no central medullary
cavity in the early periods of intra-uterine life ;
but in the foetus at its full term, the animal
matter which occupied that space has begun to
be absorbed, and the deposition of osseous
matter takes place in the form of a cylindrical
sheath, so that the canal exists at this period,
though in an incomplete state. The medullary
canal is analogous to the cells of the short and
flat bones, and of the extremities of the long
bones, which are also incomplete in infancy.
The shape of the cylindrical bones is mani-
festly different from that which they afterwards
assume; thus there is a much smaller dispro-
portion between the diameters of the extremi-
ties and that of the shaft; the surface is less
furrowed by sinuses or roughened by ridges;
differences exactly corresponding to the imper-
fect development of the muscles, which, when
more bulky in their middle portions, require a
larger space for their accommodation about
the body of the bone, and when stronger in
contraction, require attachments that will match
them in firmness. The osseous system is not
complete till after the age of twenty.

There is no part of the skeleton in which we
have a more striking illustration of its gradual
development than in the bones of the face and in
the cranium. It is not till the seventh year that
a separation begins to take place between the
tables of the skull, that the frontal sinus begins

70

to open, that the nasal bones lengthen, that the
cells of the malar and upper maxillary bones
are enlarged, that in consequence of this ex-
pansion of their cavities the outer lamina pro-
et, and that the lower jaw is elongated.

e stationary condition of the tabula vitrea
is conformable to the arrest in the increment of
the brain ; the extension of the outer table to
the increasing power and action of the muscles
attached to it; the development of the sinuses
and cells to that of the voice and certain of the
senses; and the projection of the jaws to the
increased number of the teeth. But although
these changes commence as early as the seventh
year, they are not complete till the twenty-first,
or even later. At this time the countenance
becomes settled, not merely by the full deve-
lopment of the muscles, which express the
predominant emotions of the individual, but
also by the complete adjustment of the bony
arrangements just enumerated.

Those portions of the osseous system which
are employed in protecting the organs enclosed
by them from external compression or injury,
have attained a degree of growth far surpass-
ing that of the bones devoted to locomotion
and to the mechanism of sensation. The ribs, for
instance, defending the lungs and the heart,
and playing so important a part in respiration,
are farther advanced in the ossific process than
the bones of the extremities. But the most
striking fact of this kind is presented in the
spinal column. The annular portions of the
vertebrae which form the canal of the medulla
spinalis, are found strongly ossified at birth,
but the bodies of these bones, which are to be
used hereafter in supporting the weight of the
head and trunk, are very slightly expanded,
and all but devoid of earthy particles, while
the processes to which the muscles employed
in the flexion and extension of the column after-
wards contract attachments, are either only
shaped in cartilage, or may be said to have no
existence.

Passing from the bones to the muscles, we
observe the latter no less incomplete in infancy
as it regards their physical characters; they are
pale, flabby, and easily torn; they contain less
fibrine than in after years; their contractility is
weak though easily excited; and the fasciculi
and fibres are but loosely connected from the
want of the fascia and aponeuroses which brace
them in later periods. As life advances, the
fibres become redder, more distinct, and
stronger. A readiness to contract is manifested
very early, but it is not till maturity that these
organs are able to maintain contraction for any
length of time. They suffice well for the quick
and buoyant motions of the lively child, but
fail in those violent and prolonged exertions
required by the labours of manhood. The
form of the muscles changes materially in the
progress of years ; thus, they swell out in the
middle, and occasion a great difference in the
proportions of the limbs. Those portions of the
locomotive apparatus attached to the muscles
and articulations, viz. the tendons and liga-
ments, undergo corresponding changes. In
infancy they are soft and gelatinous ; gradually

AGE.

they“ become firmer, their gelatine pat rd
a more glutinous character, and the membrane
which envelopes them ismore condensed. Every
one knows the different products obtained by
boiling the tendinous parts of young and adult
animals ; in the one ‘a have the qualities of
jelly, in the other of glue. The readiness with
which the joints of a child are strained or dis-
located is likewise well known. The imma-
ture condition of the infant is strongly marked
in the ankles, which are turned inwards, and
would never suggest the use to which the feet
are to be applied, but for our familiarity with
the change that afterwards occurs. The car-
tilages and fibro-cartilages are subjected to
a development corresponding to that of the
fibrous tissue.

Into the composition of the vocal appa-
ratus we know that muscular, fibrous, and
cartilaginous tissues enter; and, as these
are altered by age, the mechanism which
they constitute might d@ priort be expected
to suffer similar modifications. The larynx
of the infant is small and almost pe
consequently the lips of the glottis and
the superior ligaments are very short. This
configuration, viewed in connection with the
immaturity of the muscular tissue, accounts for
the shrill wailing cry, which is the only vocal
sound produced at this early period of human
existence, and the only one required, since
the quick instinct of maternal affection can
interpret these simple notes into an eloquent
language. No very appreciable alteration takes
place in these parts at the time when speech is
acquired, for this attainment has more con- ~
nection with the development and command of
the muscles of the pharynx and mouth, as well
as with the organ of intelligence, which enables
the human being to discriminate sounds and to
imitate them. Fortunately the oral and pha-
ryngeal muscles are some of the foremost in
development, being required in suction and
deglutition. A progressive change goes on in
the larynx, though it is not very evident till the
period of puberty in the male, when the thyroid
cartilage is elongated, and with it the thyro-
arytenoid muscle. At this epoch occurs the
moulting of the voice, or an accession of gravity
in the tones, occasioned by the elongation of —
the parts just mentioned. The projection of —
the pomum Adami takes place at the same —
time. In the female larynx scarcely any change —
occurs, and the voice in consequence remains
acute. We have already spoken of the facial —
bones and their cavities, parts which exercise
a very decided influence on the sonorousness —
of the voice. :

We must now hasten to the consideration
of the parts employed in that other distin-
guishing function of animals, viz., sensation.
There are two grand divisions of the organs of
sensation, those which we understand, and those
which we do not. he

The former consist of the
various kinds of animal mechanism whereb:
the external causes of sensation are modified, the
latter of the nervous substance intermediate to th
external excitant, and that state of consciousnes
which we denominate ‘sensation. We kn

that the eye collects rays of light and con-
centrates them on its internal surface, but are
utterly ignorant of the changes which the re-
tina, the optic nerve, and the brain undergo in
producing that condition of our sentient exis-
tence which we call vision. It is true that we
are aware that certain states of these parts are
incompatible with sight; but why they are so
is quite beyond our knowledge. We are, as it
regards our acquaintance with the adaptation of
nervous tissue to the production of sensation,
in the same predicament as a man who watches
the working of a steam-engine, and knows that
a certain quantity of fuel, of water, of valvular
compression, &c. is necessary to its motion,
but has no idea of the laws of caloric, vapori-
zation, constitution of elastic fluids, &c. Our
science demonstrates the fitness of the external
and internal ear for receiving, propagating,
multiplying, and diffusing vibrations, but why
the contact with the auditory nerve produces
sound, is an all but impossible inquiry; as well
as the reason why the sensation may be absent
when the organ is in perfect order, and the
nerve to all appearance unchanged ; or why the
sensation may occur without vibrations, as in
dreaming, and many nervous disorders. The
same may be said of the skin; it is well
adapted for coming in contact with the points
or superficies of bodies, but who can say why
the nerves spread over it occasion certain feel-
ings? These remarks are premised merely to
shew that it must not excite surprise, if we are
unable to point out completely the changes
which age produces in the human body, corres-
pondently with the changes of its sentient fa-
culties.

It has already, in all probability, struck the
mind of the reader, that the great develop-
ment of the cerebral system in the infant is
inconsistent with the principle which we have
been endeavouring to demonstrate, viz., that the
growth of the human body consists essentially
in the elevation of the organs, subservient to the
animal functions, from a rudimentary state.
The more we grow, the smaller is the proportion
of the brain to the rest of the fabric. But it
is no less true that the functions of the brain
grow with our growth. How then are we to
reconcile these opposite facts? We must cer-
tainly discard the opinion, that the bulk of the
organ is proportionate to its power, and exa-
mine the composition and the relations of its
_ Various parts to each other.

_ Limited as our knowledge is of the requisite
_ conditions of nervous substance for its func-
tion, we are notwithstanding aware of two ex-
tremes of softness and hardness, which comprise
those states of the tissue which are compatible
_ with the exercise ofits peculiar faculty. Patholo-
gists well know that ramollissement and indu-
Tation of the brain may produce the same lesion
_of function, viz., abolition of sensation ; while it
is equally well known that approximations to
_the same conditions will produce impairment of
this faculty. Now in infancy the brain is ex-
tremely soft, almost pultaceous, while in old
_ age it is extremely hard in comparison, and the

Similarity of the two ages in many: respects,

AGE.

71

but particularly as it regards the functions of
the nervous system, is matter of universal ob-
servation. It might then @ priori be suspected
that one of the changes in cerebral growth
would be a tendency to a certain intermediate
degree of consistence, and this is found actually
to be the case.

From a careful comparison of the size and
weight of the brain at different ages, it was ascer-
tained by the Wenzels, and is demonstrated in
tables contained in their work, De Penitiori Cere-
bri Structura,* that although the organ increases
very sligthly in bulk after the third year, its
weight does not attain its maximum till after
the seventh, so that up to this time there is a
progressive increase of density. After the
seventh year there is no great difference either
in size or density. (The size of the brain must
not be confounded with that of the head, which
after the period that we speak of, is determined
by the growth of the external table of the skull,
correspondently with the projection of the bones
of the face.) There must, therefore, be some other
change than that of density, to account for the
augmentation of intellectual power in the suc-
ceeding periods, and herein our information is
most at fault. Nevertheless we are not altogether
without intimations of organic changes. The
majority of physiologists are agreed that the
function of the cortical substance is of a higher
character than that of the medullary. The
lower we descend in the animal series, the less
we find of the cineritious matter, which is not
apparent at all in the invertebrata, nor indeed
in fishes. It is, therefore, not without proba-
bility conceived that this matter is more imme-
diately concerned in thought ; and, conformably
with this view, we find its colour more strongly
marked, as boyhood stretches on to manhood.t
We may mention as corroborative of this cir-
cumstance, that M. Foville, an eminent in-
vestigator of the pathology of mental diseases,
asserts that the principal lesions in the brains
of maniacs occur in the grey tissue.[ The
convolutions again afford us some hints upon
ithe subject before us. Intelligence is in direct
proportion to their extent, and we accordingly
find that these parts are deeper as age advances.
As the existence of the posterior cerebral lobes,
and of the corpus rhomboideum in the cere-

* See the notes to Milligan’s Translation of
Magendie’s Physiology.

+ This observation refers to the cineritious matter
of the convolutions. In certain other parts this sub-
stance diminishes after birth. Thus, in the full-
grown foetus, the medulla oblongata is grey through-
out, but soon begins to whiten, first in the corpora
pyramidalia, and afterwards in the olivaria. The
outer surface of the tuber annulare, and of the
crura cerebri, is also grey at the commencement of
extra-uterine life; but they lose this colour after
a few weeks. In the thalami optici and corpora
striata there is no distinctiun of white and grey
matter, the latter alone being visible. See Meckel,
Manuel d’Anatomie, t. ii. p. 717. ‘Till the
functions of these parts in mature age are better
understood than at present, it would be useless to
speculate upon the physiological relations of the
changes which they undergo in earlier periods.

¢ Dict. de Méd. et Chir. Pratique, arts Aliéna-
tion Mentale.

72

bellum, is observed only at the top of the
animal scale, we might expect that in the pro-
gress of age there would be a change in the
relations of these parts to the whole mass, but
we cannot find that any researches have been
prosecuted in elucidation of these points.

Most of what we have predicated of the pro-
gressive actions in the brain, is likewise appli-
cable to the cerebellum and spinal marrow,
and nerves. The latter parts, however, are
more forward in their organization, being de-
voted to the more primitive functions of sensa-
tion and voluntary motion, while the former is
the instrument of the faculties more eminently
intellectual. The proportion of the cerebellum
to the brain at birth, is, according to Meckel,
as 1°23; the former weighing nearly 3} drachms,
the latter 9 or 10 oz. A month after birth the
ratio is 1:17 ; after six months, 1:8.

The proportion between the spinal marrow
and the brain at birth, and for five months
after, is 1:107 oreven 1°112; the brain at the
former period weighing 90z. 4dr., and the
spinal marrow 45gr., while at the latter period
the cerebral organ weighs 210z., and the spinal
1jdr. In the fetus of five months the propor-
tion is 1°63, of three months 1:18. In the
adult it is 1:40. The diminishing ratio of the
brain to the spinal marrow is in obvious har-
mony with the elongation of the vertebral
column, and with the general growth of the
members. The medulla oblongata is propor-
tionally larger in early than in advanced life;
the corpora pyramidalia and olivaria being dis-
tinct and prominent; a fact which corresponds
with the development of the brain.

The longitudinal dimensions of the corpora
quadrigemina at birth exceed those of the adult
period; after the former period they increase
only in their transverse diameter.

The concretions of the Pineal glands have not
begun to be formed till the seventh year. They
are sometimes wanting in very advanced age,
according to the observations of Meckel and
the Wenzels, which we have had oppor-
tunities of verifying by our own dissections.
The number of these bodies increases with the
progress of life, and their colour is paler in
youth and old age than in intermediate
periods.*

So much then for the nervous organs of
sensation. Our attention must next be directed
to the mechanism intermediate to the nerves,
and the excitants of sensation. The simplest
kind of sensation is that which informs or re-
minds us that we are possessed of bodily parts,
such as members and internal organs. The me-
chanism employed, if there be any,is unknown.
Nerves are distributed through the tissues, we
feel those tissues, and conclude that these feel-
ings result from relations between the nerves and
the other textural molecules with which they are
in contact. These feelings must of course var
with age because the tissues alter, but whether
the susceptibility is increased we cannot say,
and only venture to remark that the proba-

* For further details see the works of Meckel and
Tiedemann.

AGE.

bility of this being the case is suggested by the’
fact, that adults are more subject to perver-
sions of sensibility than children; wi the
various nervous, hypochondriacal, and hys-
terical disorders with which adults are almost
exclusively visited.

The next order of sensations in respect of
simplicity are those of tact, or those by which
we are made acquainted that foreign bodies
are in contact with our skin. It is perhaps in’
some respects only a modification of the first-
mentioned sensation, but it requires the pre-
sence of something not belonging to us. It is
true that other parts than the skin may convey
the notion of an external body being applied to
them, but they do not afford any perception of
the qualities of the body; it is merely the
affection of themselves which is produced by
that body. We are aware that all sensation
may be analysed in the same manner with
similar results, but it is enough for our present
purpose that the sensation excited on the skin is
less selfish, if we may use the term in this sense,
and ought to be so, in order that it may serve
its office of supplying some knowledge of the
external world. Doubtless the organization of
the epidermis and of the skin itself, as well as
the greater distribution of nervous matter, occa-
sion the difference. The dermoidal tissue in
modifying the external cause stands in the same
relation to the nerves of tact, as the eye to the’
optic nerve, or the nose to the olfactory. The
organ of tact is affected by age; the skin in
very early life appears less susceptible of im-
pressions, and differs in its tissue, the papille
being less developed. A change, however, is
soon effected in this respect, and as we advance
towards manhood, it becomes less gelatinous
and more fibrous. It must be confessed, how-
ever, that the modifications which it undergoes
in reference to its function of sensation, are not
well defined. This circumstance is owing to
the variety of sensations to which it ministers, |
such as (in addition to what we have men-
tioned) feelings of heat and cold, dryness
and moisture, &c. and, secondly, to its being
also an organ for other and very different func-
tions, such as transpiration, secretion, and ab-
sorption.

Touch has a far more complicated mechanism
than tact. It is one of the senses properly so
called, or the special senses, and like the others
of its class is distinguished by its requiring the
assistance of muscles. Its sensations are com-
pounded of tact and muscular resistance, and
the organ is that wonderful instrument the hand.
The imperfect state of this organ in infants must —
have been noticed by every one ; it is generally
closed and capable of grasping but very feebly; _
at all events a long time occurs before the
little being learns to arrange the sensitive
tips of the tingers, and to adjust the thumb in
such a manner as to ascertain with nicety the
form, consistence, and other properties of
bodies. Whether the skin is less sensitive in
these subjects we cannot say, but it is qu
certain that the muscles, which effect the dig
motions alluded to, are not peter $e any
than those in other parts of the body. 1

AGE.

ness of touch, tactus eruditus, is one of the
most difficult attainments of manhood.

Concerning the alterations in the olfactory
apparatus we have already spoken, when the
development of the facial bones was under
consideration. The sense of smell is mani-
fested pretty early, but there can be no great
precision and nicety in its exercise, both from
defect of surface, and from the want of mus-
cular power and command, in adjusting the
quantity and impetus of the air that conveys
the odorous particles. Thus, some agents are
only appreciated by a sudden inhalation through
the nostrils, as if to bring the particles with a
certain degree of force upon the Schneiderian
membrane. This art the child does not under-
stand.

Taste being a sense so essential to the main-
tenance of the system, whether by inducing the
animal to take the trouble of eating, or by
warning him of improper aliment, is mani-
fested very early. The usual description of the
mechanism of taste would give just cause for
questioning what was said respecting the ne-
cessity of a co-operation of muscular action
with the five senses. Taste is described as
the result simply of the application of sapid
bodies to the tongue, palate, velum palati, &c.
But these bodies excite no sensation without
the aid ot muscles. A certain degree of com-
a is necessary, which is accomplished

y pressing the tongue against the roof of the
mouth. Any one may assure himself of this fact
by placing a strongly flavoured substance on
the tongue when projected from the mouth;
no taste will ensue till the member is with-
drawn and then pressed against the palate.
This observation applies not only to the tongue
but also to the palate itself, and that sensitive
surface the velum. In each instance, however,
the effect may be imitated, by compressing
with the finger the part where the substance is
applied.

aste must undergo a progressive develop-
ment correspondently with the muscular or-
gans. It is, to say the least, very doubtful if
a child could perform those delicate manceuvres
of the tongue and palate, which are practised
by gourmands or professed wine-tasters. There
is something more than this muscular action,
however, to be taken into consideration. The
more refined flavours are probably felt and
estimated by the lining cattaehe of the nasal
es. It is common to remark that the
scent of a substance is similar to its taste, but
‘in all probability the two sensations are iden-
tical ; for the taste in question is not perceived
if the nostrils be closed; witness the abolition
of taste duringacatarrh. If therefore so close
a connection exists between the two senses,
it is clear that the development of the organi-
zation belonging to the one must influence the
other function ; and it has been already pointed
out that the olfactory surface increases with

The new-born infant is probably all but deaf;
even the loudest sounds tees no sensible
impression. The nurse’s lullaby, therefore, is
for some time superfluous ; by degrees, how-

73

ever, the shrill tones, of which such strains for
the most part consist, begin to be appreciated ;
the precise period however we do not know.
In correspondence with this obtusity we find
the organ incomplete, but the incompleteness
has reference rather to the external than to the
internal ear. Thus the pinna is very inelastic,
and therefore unfitted for collecting vibrations ;
the same may be said of the meatus auditorius.
In like manner, the membrana tympani is very
oblique, and scarcely more than a continuation
of the superior surface of the meatus, and thus
little calculated to receive the vibrations. These
parts are also covered with a soft matter very
unfavourable to vibrations ; the tympanum is
very small, and the mastoid cells do not exist.
Tn the progress of age all these parts gradually
increase in hardness, and consequently are bet-
ter adapted to their function. ‘There are mus-
cles attached to this sense also, but we are
deficient in observations on their degree of de-
velopment, though we may infer their condition
from analogies in the rest of the muscular
system.

Lastly, we come to the organ of vision, of
which, however, there is not much to be said.
The differences between the visual organ in the in-
fant and in the adult consist more in degree than
in kind; thus the sclerotic membrane is less
elastic, and the cornea is less conical, in conse-
quence of the smaller quantity of aqueous hu-
mour; (the greater thickness of this coat is pro-
duced by the serosity contained between its la-
mine ;) thecrystalline lens is lessdense, but more
convex in form. The pigmentum is in smaller
quantity at birth than afterwards; while the retina
is thicker and more pulpy than in more ad-
vanced periods. The yellow tint of the foramen
of Soemmering does not become visible till
some time after birth, but deepens with the
progress of life, till the stage of decline,
when it grows paler. It has been ascertained
that perfect images are formed on the retina;
and yet for the first few days the child gives no
indication of visual sensation, and when objects
appear to attract its attention, they are only
those which are vividly illuminated. The de-
ficiency therefore must exist in the optic nerve,
though we are ignorant of the organic condition
on which this insensibility is dependent. We
observe, moreover, that the eye is much more
passive than in the adult, that it follows the
motion of luminous bodies, or is fixed upon
them with little or no apparent interference of
the will. This muscular incompleteness, then,
tallies with what we have noticed with respect to
the other senses. The eye is known in its advance
towards manhood to increase in the capability
of adapting itself to different distances; but as
we are ignorant of the mechanism made use of
for this purpose, it is useless to look for cor-
responding organic alterations. We must not
omit to notice those appendages to the appara-
tus of vision, called eyebrows, which become
much more prominent as life advances, by the
development of the frontal sinuses, and are
therefore better adapted for shading the eyes.

The generative apparatus is situated inter-
mediately to the animal and the organic system.

74 AGE.

The evolution of the organs connected with this
function marks the age of puberty; and the
changes in which this evolution consists, both
in the male and in the female, are too well
known to require their specification here. The
influence of this development on the mental
and moral characters of either sex, is likewise
sufficiently familiar even to the most superficial
observer.

The human being is related with the external
world passively and actively, independently of
those organic actions and reactions that are
constantly occurring in his system with regard
to outward agents. He derives perceptions
from objects about him, and he reacts on them
by his power of muscular motion. But in his
growth we mark that the perfection of those
organs, which are scarcely more than passive
in his relative life, advances much more ra-
pidly than those which enable him to take a
more active part. Thus the eye and the ear
attain a certain maturity of organization and
function, long before the bones and muscles,
which officiate in locomotion. The bones and
muscles connected with the organs of sensation,
and therefore partaking of the passive character,
are also equally forward in their development.
What is the probable final cause of this
arrangement? If all our voluntary motions
were the immediate consequences of our sen-
sations, as some of them undoubtedly are,
such as those which close the dazzled eyes, or
refuse the bitter food, or withdraw from pain-
ful contact;—if all these followed directly on
sensations, it would indeed be a strange ano-
maly, if the systems that belong to each were
not precisely on the same level of development.
But this is not the case; all the more impor-
tant motions, important as it regards that world
in which man exists, as an intelligent and
social creature, though less so as it respects his
individual being, are the results of a mental
condition, no less distinct from sensation than
from muscular motion. This state is desire, or
as it is commonly called when the antecedent
of action, will or volition. Probably no men-
tal state is more simple than this, and it may
follow any other. It is therefore the more
necessary that it should be preceded by such
intellectual changes as will give it a right
direction ; in other words, that it should come
under the dominion of certain faculties. But
in early life the faculties to which we allude
are very imperfectly developed; those only
have attained any thing like maturity which
are in immediate relation with the senses;
such are perception, memory, association, and
imagination; while the reflective faculties,
such as comparison, reasoning, abstraction, all
in fact that constitute man a judicious expe-
rienced agent, are rudimentary. The conse-
quence is that the desires or volitions are pro-
verbially vain and dangerous. Let us observe
a child of seven years old ; his senses are suffi-
ciently acute for all ordinary purposes, although
they are deficient in precision and delicacy;
he has seen many attractive objects, he has
heard many wouderful stories, and tasted man
exquisite delights; he remembers them vividly,

he associates them rapidly, and often in shapes
very different from those in which they were
formerly combined. Desires follow which

would prompt him to execute the most ridicu-_

lous and mischievous schemes. But happily
the muscular system, by which alone he could
accomplish them, is too immature and feeble
for his puerile purposes. Here then is the
final cause that we were in search of; the active
corporeal functions of relation must not ad-
vance beyond the governing faculty of the
mind.

But why, it might hastily be asked, should —

not the senses, the mental faculties, and the
motive powers, all have been equally deve-
loped? The question is absurd, if we consider
but a moment the manner by which the mind
accomplishes its growth ; that its higher powers
result from the accumulation of innumerable
sensations, by which in fact the former are
nourished and exercised.

We shall now introduce a brief account of
some researches upon the height, weight, and
strength of the human body, at different ages,
prosecuted by M. Quetelet, of Brussels. Not
having room for the numerical tables, or the
particular observations, from which his general
conclusions are derived, we must content our-
selves with a statement of the latter, and refer
those of our readers who may be desirous of
seeing the former, to the author himself. His
deductions as to the growth of human stature
are as follows: (1) the growth is most rapid
immediately after birth; it amounts in the first
year of infancy to about two decimetres
(nearly eight inches.) (2) The growth dimi-
nishes as the child advances towards the
fourth or fifth year; thus, during the second
year his increase of height is only half what it
was the first year, and during the third year it
is not more than one-third. (3) After the
fourth or fifth year, the stature increases pretty
regularly until the age of sixteen, and the an-
nual zrowth is about fifty-six millim, (two inch.)
(4) After puberty the stature still increases,
though slightly ; thus, from the sixteenth to the
seventeenth year, the increase is about four
centim. (1%inch); and in the two following
years, only two centim, and a half (one inch.)
(5) The stature does not appear to be quite
completed even at the age of twenty-five.—
These observations refer only to absolute growth,
but if the annual increase of stature be com-
pared with the height which has been attained,
it will be found that the infant, after birth,
increases in the first year by two fifths of
his height; in the second by one-seventh ;
in the third by one-eleventh; in the fourth
by one-fourteenth; in the fifth by one-fif-
teenth; in the sixth by one-eighteenth; &c.

so that the relative growth continually dimi- —

nishes after birth.

In addition to these statements M. Quetelet —
has ascertained that the rules of growth are not —
the same in both sexes; 1st, because the female —
at birth is less than the male; 2dly, because

her development is completed earlier; 3dly,

because her annual growth falls short of that of

the male. It appears likewise that the stature

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of persons living in towns, taken at the age of
nineteen, exceeds that of residents in the coun-
try by two or three centim (1 or 1} inch); and
that the children of persons in easy circum-
stances, and those of studious habits, are gene-
rally above the middle height.*

A memoir by the same author devoted to an
examination of the weight of the human subject
at different ages, contains a series of interesting
conclusions, from which we select the following.
(1.) At'the period of birth there is an inequality
both as to weight and to stature, in the two sexes ;
the medium weight of males being 3 kil. 20,
(rather more than 7 Ibs.), that of females 2 kil.
91, (about 6ilbs.); the height of the former
Om. 496, (about 19 inch.); that of the latter
Om. 483, fabout 18inch.) (2.) The weight of
the infant diminishes the first three days after
birth, and does not begin to increase till the
second week. (3.) At the same age the male is
generally heavier than the female; it is only
about the twelfth year that their weights are
equal. Between the first and eleventh year the
difference of weight is fiom 1 kil. to 1 kil. and
a half; between sixteen and twenty, about 6 kil.
and after this period from 8 to 9 kil. (4.) At
full growth the weight is almost exactly twenty
times what it was at birth, while the stature is
only about three and a quarter more than it
was at that period. This holds good with both
sexes. (5.) In old age both sexes lose about
6 or 7 kil. of their weight, and 7 centim. of
their height. (6.) During the growth of both
sexes, we may reckon the squares of the weights,
at the different ages, as proportional to the fifth
powers of the heights. (7.) After full growth
m each sex, the weights are very nearly as the
squares of the heights. (From the two prece-
ding statements it may be deduced that the
increase in the longitudinal direction exceeds
that in the transverse, including in the latter
both width and thickness.) (8.) The male at-
tains his maximum weight towards the fortieth
year, and begins to lose it sensibly towards the
sixtieth. The female does not attain her maxi-
mum weight till about the fiftieth year. (9.)
The weights of full-grown and well-formed
persons vary in a range of about 1 to 2, while
the heights vary only from 1 to 1}. This state-
ment is deduced from the following table :+

Mazimum. Minimum. Medium.

KIL. KIL. KIL.

Male weight .... 98.5 49.1 63.7
Female ........ 93.5 63.7 55.2
MET. MET. MET.
Male stature .... 1.990 1.740 1.684
Female ........ 1.740 1.408 1.579

* Recherches sur la loi de la Croissance de
V’Homme, par M. Quetelet. Annales d’Hygiéne
Publique, &c. t. vi. p. 89.

+ Ann. d’Hygiéne, t. x. p.27. To the above
memoir M, Villermé has appended some extracts
from manuscript notes found among the papers of
M. Tenon, and written about the year 1783. They
contain observations which correspond, in many re-
spects, with those of Quetelet.

The last researches of this industrious ob-
server have been devoted to the muscular power
of man at different ages, and have been but
very recently published.’ In the course of his
memoir he refers to two tables; one stating the
relative power of draught (la force rénale), at
the several periods; the other, the relative ma-
nual strength (la force manuelle); in each case
estimated by the dynamometer. The results
are very much what might be expected a priori.
It appears that the maximum of the “ force
rénale” is at the age of twenty-five ; and that
the difference in the extent of this kind of mus-
cular power between males and females, is less
during childhood than at the adult age. Thus,
in the former period the male surpasses the
female by one-third, towards puberty by one-
half; and at full growth, his strength is double
that of the other sex. The manual force is
greatest at the age of thirty, and at all ages is
greater in the male than in the female; before
puberty, in the ratio of 3: 2, after this period,
in the ratio of 9:5. The average manual
strength of a man is equivalent to 89 kil. and
exceeds his weight by 19 kil., so that he might
support himself by his hands only, even with a
considerable weight attached to his feet.*

This and the preceding memoirs, we are
told by M. Quetelet, are extracted from a work
which he is about to publish, entitled “ Sur
Homme et le développement de ses facultés ;
ou, Essai de Physique Sociale.” We need
scarcely add that we are justified in expecting
from the specimens already presented to us, a
series of valuable and highly interesting facts,
together with deductions of no ordinary im-
portance and originality.

Having thus briefly traced the changes that
precede maturity, we may ask what is it that
prevents the processes of growth from advancing
at the same rate as they have hitherto done?
Why, so long as they are undisturbed by dis-
ease or unnatural circumstances, should they
not advance ad infinitum, or at least why
should they not raise man to the strength and
dimensions which poets have fabled in their
Titans? The same food, the same atmosphere,
the same light and heat, the same electric
agencies, by which the organs have been main-
tained or excited, are still around them and
exerting their influence. Why, then, should
they never transcend a certain point? Why
should the stature, however much it may vary
between a Boruwlaski and an O’Brien, yet
never rise above a certain measure ? Why does
the strength never exceed the powers of a Milo
or a Desaguliers, or the intellect surpass the
limits of Aristotle, Shakspeare, or Newton?
These are interesting but impossible problems.
If we say that a certain quantum of vital power
is allotted to the growth of man, and that while
a portion is expended in raising him to matu-
rity, the residue must be husbanded for con-
ducting him through the remaining portion of
his duration, else he might suddenly stop short

* Ann. d’Hygione, &c. Oct. 1834, t. xii. p, 294,

76 AGE

in his career without passing those stages that

prepare him for the cessation of his existence ;
—what do we gain by such an explanation?
Nothing; for the term vital power which we
employ is but a hypothetical cause, or if more
closely examined, is scarcely even this ; it is
but an abstract term applicable to a number of
actions that do not occur in the inorganic
world. The vital power of a body is but the
collective manifestation of its vital actions, and
to say therefore that only a certain quantum of
vital power is inherent in it, is but to express
in other words the simple fact that those actions
are circumscribed. Discarding this explana-
tion, shall we say that the fact must be referred
to some deficiency in the media of the being’s
existence; that, although the aliment, the air,
the light and caloric are competent to the pro-
duction of a certain degree of growth, they
cannot extend it, and that, were their conditions
different, the animal development would be
more perfect. It is easy perhaps to suppose
this, but we do not see how it can be proved,
nor indeed that existing analogies favour it.
On the surface of our globe there is every
variety in the temperature, in the humidity, and
in the electric conditions of the atmosphere,
and every diversity in the articles of food em-
ployed; in more limited spheres there are the
greatest diversities in these several respects
produced artificially by the various occupations
of mankind ; and although we find, both among
races and individuals, great varieties of deve-
lopment, which may occasionally be traced to
some relation with the media in which they
live, these varieties are by no means in propor-
tion to the differences of the media, and in the
majority of cases the former are independent
of the latter. In the temperate zone, with a
due proportion of animal and vegetable diet,
man appears to attain his most perfect deve-
lopment, and with however great skill he
adapts these circumstances, he never surpasses
a certain point, and from what we know of his
physiology no great alteration in any one of the
external stimuli of his existence could be tole-
rated. A different proportion of the oxygen,
nitrogen, and carbon in the atmosphere, we
know full well to be noxious; a larger or
smaller quantity of aqueous vapour suspended
in it will occasion many well-known maladies ;
the same may be said of alterations in the ba-
lance of the electricity that surrounds us. Great
extremes of heat and cold may be borne for
awhile, but it is obvious that they are not so
well adapted to a healthy state of the system,
and therefore to its growth, as intermediate de-
grees; and consequently it is not easy to con-
ceive any degree either above or below these
limits consistent even with existence. Fami-
liar enough also are we with the effects of full
and sparing, of simple and mixed dietetics,
and with the fact that between certain well-
known bounds lie thé salutary quantities and
qualities. From all which it appears suffici-
ently evident, that we cannot conceive any
difference in the amount or properties of the
known stimuli of life, that would be more

favourable to the growth of man, than those.
which are to be found in the range of the known
variations, whether natural or artificial. From
the beginning there must have been established
a direct relation between the organization of
the body and the outward elements; the latter
are nothing but stimulants adapted to co-exist-
ing susceptibilities, or to put it more closely,
man is not made by, but for or with, the sur-
rounding agents ; his lungs are fashioned in cor-
respondence to theatmosphere which he breathes,
his digestive organs to the food that is spread
so plenteously before him, and his nervous
system tothe subtle imponderable agents that
play about him; consequently as his organs
only act in concert with, and do not result from
the media of his existence, a development be-
yond that which he is known to acquire must
proceed quite as much from the former as from
the latter; and the supposition, the value of
which we have been endeavouring to estimate,
thus falls tothe ground. If man could become
a larger, more powerful, or more sagacious
animal than he now is, he must not only live in
different media, but must possess a different
constitution; in other words, the characters
that distinguish him as a species must be
altered. The question, then, that offered itself
remains to our apprehension unsolved by either
of the hypotheses. The limitation of man’s
development is like the definite period of his
duration, and a hundred other circumstances
connected with his existence, an ultimate fact ;
no event that we are able to discover intervenes
between its production and the will of the
Deity.

Maturity, though varying with every indi-
vidual, may be said to take place somewhere
between the ages of twenty-five and thirty. It
is a general opinion that it is a stationary con-
dition ; that when such changes have taken
place in the frame, as render the human being
capable of undertaking the various duties and
occupations to which adults alone are adequate,
there are no further alterations till the period of
declining age ; that, in short, growth has entirely
ceased. But this idea is not strictly correct,
for there is in all probability no period when
the system is absolutely stationary; it must
either be advancing to or receding from the
state of perfection. This is of course more
obvious when we know that augmentation of
bulk is only a part of that process which per-
fects the organization. (See Nurririon.) It
is true that at the adult age the determinate
height and figure, the settled features, the
marked mental and moral character, naturally
give rise to the idea that a fixed point has been
attained ; but a little inquiry soon teaches us
that the individual is still the subject of some
progressive changes. It is the stature only that
is stationary, for this depends on the skeleton,

which ceases to lengthen before the period we —

speak of. But the capability of powerful and
prolonged muscular exertions increases for some
years ; there must consequently be a change in
the muscular tissue.
have not attained theiy maximum, although we

The intellectual faculties —

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do not hesitate to consider them mature; we
must therefore infer that there is a correspond-
ing organic development of some kind in the
cerebral substance. Maturity then would, ac-
cording to this view, require to be dated at a
period much later than that which is usually
assigned to it. It is enough, however, without

_ referring further, to know that although at the
adult period the organs of animal life are so
developed, that we cannot consider them im-
perfect instruments, they are even afterwards
the subjects of a perfectionnement. What is
commonly meant then by maturity, is in strict-
ness that period of human existence, during
which the processes of growth and decline are
passing into each other by such slow degrees
as to be imperceptible.

In this important era of the life of man,
more important even than the season of adole-
scence, we must leave him in the full posses-
sion of all the faculties and energies which his
Maker has allotted him, fulfilling his destiny of
good and evil, encountering and triumphing
over peril, toil, and pain, scaling the rough
steep of ambition, threading the dark intricate
paths of gain, labouring for the happiness or
misery of his fellow-creatures, supported all
the while by the consciousness of a strength
that seems never to fail him, of resources never
to be exhausted ; we must allow a few years to
roll by, and then return to him, when weary,
wayworn, and broken with the storms of life,
he has discovered that there are limits to his
powers of action and endurance ; that of the
objects which he proposed as the ends of his
labours, while a few have been accomplished,
the majority are either vain or unattainable ;
and that a race fresh in vigour, and high in
hope, the images of his former self, are over-
taking and thrusting him away from the scenes
of his exertions. What are the revolutions
that have transpired in his system ?

The formative organs of all the tissues of
the body are in reality the tissues themselves ;
whether it be a muscle, or a gland, or the coat
of a vessel, the parts which essentially produce
its growth are nothing more or less than its
own constituent molecules, the mutual attrac-
tions of which in deposition and absorption
constitute assimilation ; for there is no proof

that vessels are used for any other purpose
than that of conveying the nutrient fluids to
and from the places, where the ultimate mole-
cules arrange themselves in the form of tissue.
The altered qualities, then, which are presented
i #4 the tissues, in whatever organs, in the de-
cline of life, must depend immediately upon
alterations in their own molecular motions
and affinities. ‘The nature of these alterations
_ will of course correspond to the nature of each
tissue; and unless we mistake, they will all
be found to agree in one character, viz. a sim-
composition, a lower kind of organization

. they formerly possessed. But the discussion
of this point will be more conveniently deferred

till we shall have briefly recited the principal
_ changes in the more important parts of the

As the nutritive secretions of the various

; an

AGE.

77

structures are supplied with materials by the
fluids in those structures, it is evident that they
must at any time be increased, diminished, or
otherwise modified by changes in the quantity
and properties of these fluids. It is therefore
a natural commencement of the subject to begin
with the circulating system.

Nothing is more obvious in the condition of
the aged as contrasted with the young than the
different ratio between the fluids and the solids,
the former being remarkably deficient. There
is not only a notable diminution in the quantity
of oleaginous or serous secretions, which are
generally contained in the cellular parts of the
body, but it is manifest that the tissues are per-
meated by a much smaller hy baie of blood.
This fluid moreover is very different in quality
from what it was in earlier life; it is less arte-
rial, its colour has not the same bright red it
once presented, it has a large proportion of
serum, and its coagulum is less firm in con-
sistence.* Correspondently with the defi-
ciency of fluids, many parts which once
contained them are shrunk or obliterated. The
capillary system becomes infinitely less ex-
tended than it once was ; many of the extreme
branches of the arteries themselves are no longer
to be penetrated, and those which remain per-
vious, are far less distensible than formerly.
There is indeed a remarkable change in the
coats of these vessels; they are not only con-
tracted in diameter, but are become denser and
more rigid in texture. In this respect they dif-
fer from the veins, which in old age are more
dilatable than in youth, and consequently con-
tain a larger quantity of blood. The final
cause of this is evident; in youth the arteries
must convey a relatively larger quantity to sup-
ply the increasing structures ; in the decline of
life, when the latter are decreasing, there can no
longer be any need for the same supply;
the permission, however, of an aceumulation in
the veins, where it is less likely to be productive
of injury, appears to. be an accommodation to
the diminution of the circulating powers.

If we trace the arteries from their extremities
back to the heart, we shall find their calibres
every where diminished, their coats less elastic,
less capable of adapting themselves to the
varying quantity of their contents, in some
places resembling the texture of ligament, in
some that of cartilage, and in others studded
with deposits of osseous matter. The heart
itself presents marks of degeneration no less
decided ; its cavities are shrunk, its fibres pale,
and but feebly contractile, and fat will some-
times seem to take the place of the muscular
substance. Frequently, also, the coronary arte-
ries are found ossified, and the same alteration
is not uncommon in the valves.

All these facts account for the slow, languid,
staggering circulation characteristic of advanced
life ; there is less blood to be transmitted to the
various organs, and that which is sent is pro-

lled with a degree of feebleness that shows

ow little energy is required in its motion, when

* De Blainville is of opinion that these changes
are exaggerated. Cours de Physiologie, i. 262. _

78

so few nutritive actions are transpiring. We
have spoken of the altered character of the
blood, of its being less arterial and of a darker
tint: this change is explained by the alteration
in the respiratory system. The lungs are be-
come lighter, the cells being relatively much
larger,* and the parenchyma, which consists
principally of bloodvessels, being greatly di-
minished. This alone would not explain why
the blood is imperfectly arterialized, because,
although the respiratory surface is diminished,
less of that fluid enters the organ. But the
bronchial membrane is always in a more or less
unhealthy condition, being covered with a thick
and copious secretion, that constitutes the “ old
man’s catarrh,”’ and prevents a due intercourse
between the air and the blood. Besides this
circumstance, the expansion of the chest is less
perfect in consequence of the diminished elas-
ticity of the parietes of the chest produced by
the ossification of the cartilages and other
causes: the muscles also participate with less
energy in the respiratory movements. Every
thing in the history of advanced life indicates
the diminution in the vigour of the circulation
and respiration. The apathy and languor of
mind, the deficiency of many secretions, and
the general decrease of animal heat, but par-
ticularly in the parts most distant from the heart,
are all more or less intimately connected with
the failure of these vital actions.

On turning to the digestive apparatus we
have abundant marks of deterioration. The
teeth fall out, the alveolar processes are ab-
sorbed, and the gums become hardened. In
addition to these there is a change in the mus-
cularity of the stomach; it has become weak,
attenuated, and less contractile. The same is
true of the intestines. The lacteal vessels are
much fewer in number, and scarcely any lym-
phatic glands are to be met with. Every thing
intimates that the food is less perfectly acted
upon, and that consequently less chyle is ex-
tracted, and transmitted to the circulation.

Since, then, in these several systems, we find
marks of diminution, impairment, depravation,
it is not wonderful that nutrition, which is per-
formed by means of the materials supplied by
those systems, partakes of the same characters.
But as nutritive changes must have occurred in
the various deteriorated parts just spoken of,
it would be incorrect to say that alterations of
tissue depend solely on the alterations of these

* M. Andral, in his description of the atrophy of
the lung which occurs in aged persons, says, “ In
some cases the walls of the cells disappear alto-
gether, and we only find in their stead some delicate
laminz or filaments, traversing in different directions
cavities of various sizes. In the parts of the lung
where these alterations exist, there are no longer to
be found either bronchial ramifications, or vesicles
properly so called, but merely cells of greater or less
diameter, divided into several compartments by im-
perfect septa or irregular lamineg. Many of these
cells bear a perfect resemblance to the lung of the
tortoise tribe, and they all approach to it more or
less as to a type of organisation, towards which the
human being in this case seems to descend. Pathol.
Anat. v. ii. p. 528, translated by Drs. ‘Townsend
and West. |

AGE.

systems, though they are promoted by them;

ey must, in fact, have assisted each other.
The altered tissues could not have been easily
thus changed, without a defect in the quantity
or quality of the matters out of which they are
formed ; nor could the latter defects have easily
occurred without some alteration in the texture
of the parts employed in conveying and ela-
borating the nutrient fluid. It is an old saying,
that the functions of the body form a circle: if
this be true of their healthy condition, it is not
less so of their diseases and decline.

The organs and tissues subservient to the
organic life having undergone vitiation and
diminution, we may expect to find equal or
even greater decay in the parts which are alto-
gether dependent upon them, or the organs
of the supplemental life. These indeed, as
they are the last to be developed, are some of
the first to present marks of decline, and evi-
dently for the same reason, viz. because they
are appended to and generated by the other
parts of the system, and also are:‘more open to
our observation. The body is indeed, in this
respect as in many others, not unlike a poli-
tical community; no great change can occur in
its internal arrangements, such as a failure
or derangement of its energies and resources,
without a manifestation of this weakness or
disorder in its foreign relations.

Let us proceed, then, to examine the ravages
which are wrought by the hand of time on the
organs of locomotion and sensation, in the
same order in which we have traced the deve-
lopments and amplifications, once lavished by
the self-same agent.

And first of the bones. The process of
development in these parts consisted of a
certain adjustment of the animal to the earthy
matter, in order to give the requisite firmness,
toughness, and solidity. As life advances, the
phosphate and carbonate of lime are found to
exceed the proportion of the cartilage and
gelatine. The general conformation of the
bones is less regular; they look shrunken and
worn. When handled they feel lighter, not-
withstanding the osseous substance is in excess;
a fact, which results from the diminished
quantity of the fluids, and one or two other
circumstances to be mentioned presently. The
processes and ridges, once so eminent and dis-
tinct, are comparatively effaced ; this alteration
accords with the wasting and diminished exer-
cise of the muscles that were attached to these
eminences. On looking for the lines and spaces,
which are occupied in early life by cartilages or
membranes, and which are visible even in
manhood, we now find every trace of them
vanished. Thus, the divisions between the
epiphyses and shafts of the long bones, the
line of union between the bones of the pelvis,
and, in a still more marked degree, the sutural
outlines of the bones of the head, are no longer
perceptible. They are all filled up with bony
deposit, and the pelvis and cranium form
single bones; even the foramina by which the
nutrient arteries entered the tissue are con-—
tracted or obliterated. The cellular structure —
between the tables of the cranium is removed ; —

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AGE.

and the outer plate has approximated and
indeed become identified with the inner;
hence we see more depressions on the surface
of an aged skull.

On inspecting the internal structure of these
organs, we find the cavities that contain the
marrow much more extensive than formerly,

and the medullary tissue reduced to a con-

sistence scarcely exceeding that of oil. The
cells also of the short bones and of the ex-
tremities are more expanded, and the lamine
which form them are very much attenuated.

The deficiency of animal matter renders the
bones of the aged fragile; they are broken by
the most trivial accidents. It is also the cause
of their slowness to unite; for the activity of
assimilative, and consequently of reparative
processes, is dependent on the vascularity and
fluidity of a tissue. The lightness, however,
of these organs produced by the same cause is
beneficial, or at all events in harmony with the
state of the muscular system.

If we next turn our attention to the ar-
ticulations, we shall find that similar pro-
cesses of disqualification for former functions
have ensued. The spinal column, which
once adapted itself with such ease and flexi-
bility to the motions and curves of the
body, has become almost as rigid as a single
bone by the drying up of the intervertebral
cartilages, and sometimes by the encroach-
ments of ossification.* Scarcely any traces of
cartilages between the ribs and the sternum
can now be found; one of the causes to which
we alluded above, in connection with dimi-
nished respiration. The same deficiency of
cartilage is observable in the bones of the wrist
and of the tarsus. A change, the opposite of
mobility, may also be detected in the liga-
ments which embrace the joints; they are
dense, dry, and inelastic. The gelatine which
enters so largely into their composition has
become altered in its chemical properties;
it is less easily soluble in water, and has all
the characters of glue rather than of jelly.
Ill-adapted as this state of the articulations is
to the purposes of motion, it is, we think, not
altogether difficult to discern its appropriateness
to the human being at this advanced period.
Were the joints supple and flexible, while the
muscles have so little power, how much
greater would be the risks of accidents to the
aged man in the slight motions which he
achieves. In order to preserve their frames
from falling, those whose joints move easily
upon each other are compelled to exercise those

* “ Cependant il est rare que les fibro-cartilages
s’ossifient chez les snjets avancés en age. A la
verité on voit souvent les vertébres se réunir avec
les autres au payee d’une substance osseuse, mais
cette souture depend bien plus rarement de l’ossi-
fication des fibro-cartilages que de la formation de
lames osseuses a la circonférence des deux faces

lesquelles se regardent les coups des vertébres.
Diceadant jai observé quelquefois aussi 1’ossifica-
tion des fibro-cartilages intervertebraux, et j’ai
trouvé alors, en sciant longitudinalement la colonne
épiniére, que plusieurs vertébres étaient soudées
ensemble, et confondues en une seule masse.”—
Meckel, Manuel d’Anat. t. i. p. 364,

79

muscles which keep the limbs in the requisite
degrees of extension and stability, during cer-
tain attitudes and motions; but this end is
accomplished in the feeble old subject by the
very stiffness of his articulations.

The muscles are subject to changes no less
decided than those in the organs just men-
tioned. ‘They are pale, flabby, atrophied, and
indisposed to contract on the application of
stimuli; but the fibre itself is tough and not
easily torn, and the true muscular substance
seems to have given way in some places toa
sort of dense cellular membrane, or a yellow-
ish degeneration of tissue particularly de-
scribed by Bichat. Their tendons are often
studded with calcareous matter, and the sheaths
in which they play are rigid and unmoistened
with synovia. They obey the stimulus of the
will tardily and irregularly; the uncertain
tremulous movements, the tottering gait, the
stooping posture, the unsteady grasp of the
aged, are familiar to every one.

The organ of voice comes next to be con-
sidered. The larynx, once composed of seve-
ral cartilages that moved freely on each other,
is now a cavity capable of much less variation
in its dimensions, owing to the rigidity of its
parietes; the extent of the cavity gives in early
old age that depth of tone, which by its gravity
and solemnity excites our homage. In more
advanced age, however, the tone becomes
hoarse, shrill, and piping; this in all pro-
bability is produced by the contraction and
stiffness of the rima glottidis, but still more
by the want of vigour in the muscles of the
mouth and throat. The incapability of ma-
naging the tone, and the tremulous articu-
lation, are also results of changes in the muscles
of the larynx, pharynx, and tongue, similar to
those which transpire in other parts of the
muscular system. Many senile impediments
of speech are also produced by the loss of
teeth, by the falling in of the cheeks, and by
the disproportion of the lips to the space which
they occupy.

In our investigation of the signs of decay in
the parts that are subservient to sensation
and thought, we shall be met by the same
difficulties which formerly opposed our way,
when inquiring into the phenomena of their
development. We traced the progress ‘of the
nervous substance both in the nerves and in
the cerebro-spinal centre from the almost
pulpy state recognized in the infant, to its firm
consistence in the adult. If we now inves-
tigate the anatomical quality presented by the
tissue in advanced life, we shall find that it
has shared the alteration of nearly all the other
tissues,—that in short it has increased in density.
This fact viewed in connection with another,
namely, that ramollissement and induration
produce very nearly the same lesion of func-
tion, will account for the failure in the sensific
powers of old age. Besides this alteration in
the substance of the nerves, they are found to
be diminished in diameter; their neurilemmes
are become, like other membranous parts, much
harder and stronger. Moreover, Bichat has
remarked that the nervous tissue of old ani-

80

mals is much less easily affected by reagents
than that of younger ones; so that there would
appear to be an alteration in the chemical
composition as well as in the mechanical con-
sistence.

That which has been said of the matter of
the nerves is also true of the brain. The
whole bulk is diminished and the density
greater than in earlier years. Some, however,
assert that it is even softer than in manhood.
M. Blandin makes a remark of this kind,
in commenting upon Bichat’s statement of a
greater hardness in the tissue, and says that
it might be expected d priori, since there is so
strong a correspondence between the two ex-
tremes of life. There is reason, however, to
think that this remark, if true at all, applies
only to the cerebral organ of persons very far
advanced ; and it is not improbable that dis-
eased softening has in other cases been mis-
taken for the natural effect of age. The mem-
branes investing the brain like the neurilemmes
(for they belong to the same system) are also
thicker and more resistent. The vascularity
of the organ is greatly diminished; on a di-
vided surface no red dots are visible as at
periods less advanced.

The alterations in the mechanism of the
senses must next be considered. The skin,
which is the medium between the nerves of
tact, and external agents, undergoes great
changes in the progress of life. It becomes
drier, harder, less flexible, and at the same
time looser, in consequence of the absorp-
tion of the adipose substance. By the latter
qualities the function of the skin is more
evidently impaired, in that modification of it
more expressly denominated touch, or the
sense of tact united with certain muscular
feelings in the fingers and hands. By the
looseness of the integuments, the slowness and
weakness of the muscles, the stiffness of the
digital joimts, and that dulness of sensation
which exists in this as in every other part of the
system more or less, the hand is notably
deteriorated in old age.

In the olfactory apparatus we find that,
although the cavities and sinuses, through
which the Schneiderian membrane is ex-
tended, are rather increased than diminished
in size, the membrane itself is attenuated and
less pulpy. The nerve also is mentioned by
Rulher* to be evidently contracted and wasted.

The sense of taste so closely connected with
that just spoken of survives to the extremest limit
of existence; the final cause of which is evi-
dent. It is too intimately connected with one
of the processes of organic life to be easily
dispensed with, although one of the functions
of the superadded life. It is, however, feebler
than at periods less advanced, and requires
the excitement of more piquant aliment; this
is partly owing to the diminished sensibility
of the gustatory nerve itself, and partly to the
diminution of the sense of smell, on the per-
fection of which depends our appreciation of
the more delicate species of sapidity. The

* Dict. de Méd.. art. Age.

AGE.

surface of the tongue is more rugose than in
younger subjects, and there is generally a de-
ficiency of moisture, which is an additional
cause of diminished sensation. e233

The ear, both in its external appendages
and in its internal structure, presents certain
conditions which very well account for the
frequency of deafness among the aged. It is y
true the cartilages become harder, more elastic, '
and therefore more vibratory, but the internal
surface of the meatus is often thickened, and
obstructed by a dense cerumen. The mem-
brana tympani is more rigid and therefore less
capable of varying with the degree of*the vibra-
tions. In the internal cavity, although the
mastoid cells are enlarged as life advances,
the deficiency of the liquor cotunnii in the
vestibule, the cochlea, and the semicircular
canals, must greatly interfere with the produc-
tion of hearing. In addition to all these cir-
cumstances there is probably an idiopathic
insensibility of the nerve.

The modifications of the organ of vision are
familiar to all who have paid even the most
superficial attention to the science of optics.
The cornea is less transparent and less convex,
partly from the diminution of the aqueous
humour, and partly from the condensation of
its texture. The latter change is more marked
at the circumference, where a nebulosity is
often formed, which has gotten the name of
gerontotoxon, or arcus senilis. The pigmentum
diminishes, and the iris grows paler in con-
formity with the altered colour of the hair. !
The crystalline lens is denser, less transparent, .
and often acquires a yellow tint; the vitreous
humour likewise suffers a decrease. The retina ;
is considerably attenuated, but has increased in
firmness. The punctum luteum is paler, and
not unfrequently altogether effaced; a change
which, in the opinion of Meckel,* bears a direct
ratio to the diminution of the transparency of
the cornea. These several alterations are ne-
cessarily followed by two results—diminished
refraction of the rays of light, and torpor of the
nervous function, both of which produce pres-
byopia. That long sight bears a relation with
nervous as well as more mechanical causes is,
we think, attested by the fact that this kind of
vision is modified by temporary excitement of
the brain, as in phrenitis.t

If we now take a retrospect of the revolu-
tions which have occurred in the several strue-
tures enumerated, and endeavour to arrange ~
them under specific heads, it will be found
that diminution of bulk, deficiency of fluid,
and condensation of substance, comprehend
them all or nearly all. The attenuation has —
been generally ascribed to a preponderance of
absorption over deposition, or a reverse of that _
condition in which incremental growth consists. —
But we cannot enter upon the question here, —
and must refer to the article Nurririon, con- —
tenting ourselves with the remark that it seems
a superfluous multiplication of causes to sup

* Op. cit. t. ili. p. 261. 8a
+ See Abercrombie on Diseases of the Brain.

AGE. 81

pose that absorption increases, when the cessa-_

tion or diminution of deposition fully explains
the fact, provided the absorption is only main-
tained in its usual ratio.

Concerning the lessened quantity of fluid we
have already made some remarks, and hinted
at its relation with impaired digestion and

_ slackened circulation. Here it is sufficient to
observe that the fact is a sign of diminished
vitality, by which we mean merely a diminu-
tion of vital actions, especially of those of nu-
trition. The abundance of fluid in the young

Succulent body is adapted to the constant accu-

j mulation of new particles, and to the increasing

complexity of the organization of the tissues,

____ as well as to the reparation of waste, or to the

counteraction of decomposition ;—by the still
abundant though diminished quantity in the
adult the composition is maintained and ren-
dered more exquisite;—in the old man there is
_ only enough required to keep up that degree of
_ renovation, which is necessary to the integrity
_ _ of the structure, and even this action is less
_ __ than in former periods, because the organiza-
tion, from its chemical nature, is less prone to
decomposition. This brings us to the con-
sideration of the third general fact, or the
condensation of tissue, which will require
more particular notice, because great impor-
tance has been assigned to it by some writers.
The condensation is a result of the deficient
humidity just spoken of; but this is not all,
otherwise the condensation would be merely
that of dryness ; the tissue itself is of firmer
materials. Thus membrane becomes ligament,
ligament cartilage, cartilage bone, and bone
increases in its earthy proportions. This har-
dening of the whole body is spoken of by
many writers as the cause of decay, and ulti-

_ mately of death, by the gradual closure of all

_ the small vessels, and the obstruction to vital

motions; while the methods of averting old

' age, proposed by the same authors, turned

_ chiefly upon an artificial supply of moisture to

_ the body. Galen constantly alludes to this

| Condition when treating of old age, and the

_ means of resisting its tendencies.* Lord Bacon,

in his curious and highly interesting treatise,
entitled Historia Vite et Mortis, has much to

_ Say upon desiccation and the methods of pre-

venting it, such as bathing and inunction.

The fable of the restitution of old Asop by

‘the cauldron of Medea, he considers typical
of the utility of the warm bath in softening

the substance of the body. So much stress

‘does Haller lay on the effect of the universal

_ tendency to induration, that he tells us that one

of the reasons why fishes are so long-lived is
because their bones are never hardened to the
same degree as in the higher animals— Inter
animalia aves longeviores sunt, longevissimi
Pisces, quibus cor minimum, et lentissimum
Incrementum, et ossa nunquam indurantur.”
Prime Liner, § 972. There is, however, we
think, but little foundation for the supposition
induration stands in the relation of cause

is ser Snel ee a -

__™ See his treatises De Sanitate Tuenda, and De

VOL. I,

to the general failure of the functions of the
body. It is rather a symptom of decline, or
one of the phenomena in which decline con-
sists, and is therefore itself the effect of the
failure or alteration of some of the functions,
more especially of the assimilative. It is a
deterioration of interstitial secretion, partly
promoted by the changes in circulation, in di-
gestion, and probably in innervation, and partly
itself contributing to these changes, but pri-
marily owing its origin, like the latter, to the
ultimate law, which determines that at a certain
period decay shall transpire. It is in one re-
spect a descent in the scale of organization. This
indeed is indicated by the paucity of fluids and
by the slow nutritive motions, which conditions
are always sufficient to warrant our application
of the terms, diminished vitality or less vitalized
structure; but the substance itself, indepen-
dently of these deficiencies of action, belongs
to a more simple organization. We examine a
bloodvessel, and instead of finding its coats of
that complex texture which enables it to ac-
commodate itself by a property, known only
in living bodies, similar but superior to elasti-
city, we mean tonicity, we observe a plate of
osseous matter, unyielding, insensible, immo-
bile, possessing no other vital character than
bare assimilation or molecular growth. We
search for those admirably constructed sub-
stances which are interposed between the ribs
and the sternum, and by their elasticity give
extent and facility to the respiratory move-
ments, and we discover them converted into
the same matter as the contiguous bones, with
the coarse property of cohesion, and, as in the
former instance, with nothing but its growth to
redeem it from the character of mere inorganic
matter. We untangle the muscle, and instead
of the irritable fibre, soft in texture but firm in
contraction, we find a torpid substance, scarcely
fibrous in form, firm in mere physical cohesion,
weak in vital contraction, and consequently of
a degraded organization. The processes of
induration about the joints, the glands, and
the integuments, will all, when examined, be
found to approximate more than the former
conditions of these parts to the qualities of the
inanimate world. Homogeneousness of sub-
stance is alone an indication of a low organi-
zation, and a body which possesses both this
property and hardness, may be considered on
the very outskirts of the region of vitality.
Such are the properties of osseous deposits.
May we not here perceive an analogy with the
animals of the inferior classes? In many of
the mollusca how trifling a degree of vitality
seems adequate to the formation, growth, and
reparation of their calcareous coverings and
appendages; or.to go down to the coralines,
madrepores, and porifera, we observe that the
very lowest structure that can be considered
animal is sufficient to secrete or assimilate
those vast collections of earthy matter which
pave the ocean, and rise into islands, moun-
tains, and mighty continents. In this har-
dened constitution, this simplified but dege-
nerate structure, we see that the frame of man,
in its natural decay, loses the characters that
G

82
once distinguished it from the dust, and that
not less literally than truly it has become more
and more “ of the earth earthy.”

We have now traversed as far and as mi-
nutely as our space would allow, the organs
and tissues, with their various alterations. It
remains for us to inquire whether any one of
them may be considered to stand in the rela-
tion of cause to the others. We have already
dismissed the supposition, that rigidity and con-
cretion are productive of the other alterations,
and we also partly entertained the question,
when treating of the relations between assimi-
lation, the fluids, and the organs subservient to
circulation and digestion. But there are one or
two additional points which must be alluded to
in this place.

The decay of all the organs, concerned in
the life of relations, has been shewn to depend
on a failure in the actions which are necessary
to their generation and maintenance; these
organs may, therefore, be dismissed at once
from our inquiry into the causation or priority
of the processes of degeneration. Yet the
observation of the marked declension of the
function of the nervous system throughout the
body, has led to the hypothesis, that the
failure in this power is the ultimate fact in the
history of our decline, the fact to which all the
others may be traced. This view is suggested
by Dr. Roget in his justly-admired article on
Age, in the Cyclopedia of Practical Medicine.
He considers the general condensation of tissue
throughout the system, to be occasioned by a
diminished force of circulation, which allows
the capillaries to collapse and become obli-
terated ; the weakened circulation this distin-

guished author is inclined to attribute to a
diminution of nervous power in the muscular
fibres of the heart; whence he infers that the
declension of nervous power bears the priority
in the chain of events. We do not fee! pre-
pared to adopt the inference ; for if we admit
this failure in the innervation of the heart, (and
whether its fibres are dependent on nerves for
their contractility, is still an unsettled ques-
tion,) are we to pass over the condition of the
blood? Might we not say that the enfeebled
contractions of the heart are referable to an
alteration in the properties of its appropriate
stimulus? It is known that this vital fluid has
been less affected by respiration than in former
periods of our existence; we might therefore,
when searching for the earliest antecedent in
decay, stop at the imperfect arterialization of
the blood. But this would be, in our humble
opinion, to pause too soon. The deficient
oxygenation of the circulating fluid is sufficiently
well known to be the effect of certain changes
in the apparatus of respiration. And to what
do these changes belong? To a variety’ of
structural, functional, and nervous phenomena,
which, if pursued, would lead us into a maze
of events, from which it would be impossible
to select that which was earliest in its occur-
rence. Or if we leave the respiratory system,
and follow the blood backward to the process
of chylification, and ultimately to digestion, we
shall, as was shewn above, be equally unsuc-

AGE.

cessful in obtaining satisfaction. Or finally, if
we return to the heart, and investigate the dimi-_
nished nervous power, admitting this diminu-
tion to be alone sufficient for the debility of
circulation, is it possible to stop at this pheno-
menon? Nervous power is nothing but the
function of nervous substance, and whether the
latter belongs to the ganglionic system, or to
the cerebro-spinal, it may have undergone some
change, or have been stimulated differently
from usual. We know that the sensibility of
the nervous system is most intimately connected
with the quality of the blood, and with the force of
its impulse ; so that if it be true that diminished :
circulation is the effect of diminished innerva-
tion, it is no less true that the latter is also the
result of the former. Thus it appears that im
this inquiry we are constantly arguing in a |
circle, and it can scarcely be otherwise; the
principal structures and functions of the organic :
life commenced simultaneously ; they must,de-
cline simultaneously : they assisted one another
to grow ; they accelerate each other in the way
to dissolution. If, however, we are disposed
in some measure to qualify this remark, and
still hold that there must be some organic
changes primary in the work of decay, all ana-
logies must, we think, conduct us to the simple
processes of assimilation and secretion, into
which all the more complicated functions must |
be ultimately resolved; but we can go no
farther, for we know not what determines or
modifies the play of those subtle affinities,
motions, and contractions, in which such
changes consist.

Some fancy that the enigma is solved by the
hypothesis of a diminished vital power; but
we have already attempted to show that the
interpretation is without value, when applied to
the cessation of development ; the same reasons
render it equally useless as a key to the hiero-
glyphics of decay. Not less vain were the
endeavours of those who could satisfy their
philosophy with such a subterfuge of ignorance
as was afforded in the theory of a sum of exci-
tability, originally allotted to the system, and
gradually exhausted, &c.; as if excitability
could possibly mean any thing more than an
expression of the collective phenomena of ex-
citement, or vital movement. It is exactly on
a par with the doctrine of decreasing vitality.*
Some talk prettily and poetically of the vital
flame burning out, of oil gradually wasting, of
fuel expended,— phrases applicable enough as
metaphors, but absurd when propounded, as_
they too often are, as statements of matters
of fact.

When philosophy has failed to discover
tecedences, she may still find a prolific sou
of employment in the study of harmo
There is no event to be found in the relation ©
cause to those organic changes which, withot
the intervention of accidental agents, ultir
affix a bound to the duration of man’s exis
As no cause can be elicited for the termi
of development, neither can we better expla

ie

* «La yéne de l’influence vitale s’accroit sans

eee ee mee

j

ee et Pe eee

a

>. 4
an=-

cesse,”’-—Cabanis. j ore

ALBINO.

why growth does not continue stationary, and
maintain the bodily structures for a series of
ages, so long as externa] circumstances remain
the same. We live in the midst of agents
that both supply us with life and infest us
with poison: for a time we resist the baneful
tendencies, and then gradually succumb, but
in what manner we are at present ignorant.
The prevalence of certain functions has been
supposed to fortify certain animals against the
outward agents or inward processes that would
otherwise urge them to dissolution. The in-
fluence of respiration upon nutrition is well
known, and consequently a large sum of respi-
ration has been alleged to account for the
: longevity of birds; but there are equal or
much greater instances to be found among fishes
___and reptiles, the amount of whose respiration is
extremely small. In the one case the vitality
is said to be less rapidly consumed, in the
other to be more abundantly supplied ; expla-
nations which amount to little more than
statements of the same facts in different lan-
guage. Lord Bacon was of opinion that birds
owe their lengthened existence partly to the
smallness of their bodies, and partly to their
being so well defended by their teguments
from the atmosphere; while he accounted for
the long life of fishes by the non-occurrence
of desiccation in their aqueous element. There
4s nothing satisfactory to be obtained from
speculations of this sort. The most that we
can learn is the variation in the term of exist-
ence by the influence of various outward
agents and modes of life. But whatever
variation may be discovered, it will still appear
that climate, and time, and custom, and
science have never prolonged the date beyond
certain limits. The study of these circum-
‘stances, and the appliances of art, undoubtedly
tend to enable a greater number to attain the
extreme goal, but can never give the power
_ of transgressing it. Vain, then, as Boerhaave
observes, are the hopes of men who look for
an agerasia!
_ _ Although at present, then, we cannot trace
_ the causes of the bounded nature of our existence,
yet it is not difficult to discern its fitness to our
constitution, and to the universal frame of
things. The brevity of life is an ancient com-
_ plaint; lamentations have been chaunted over
it time out of mind: but its antiquity does
_ not redeem this, any more than many other
opinions equally hoary, from the character of
aprejudice. Every consideration of the fact in
_ question with reference to the universe must
justify the ways of God to man” in the dis-
_ position of this as of every other event. We have
only to conceive the circumstance altered, in cor-
epreneppaabe idle wish of some aspirant
_ to longevity, and we see that every thing else
also would require to be changed; that, in
_ Short, the beautiful arrangements of the world
and of our social relations would be broken.
To notice one or two of these: if the life of
-™man were longer than it now is, his progeny
_would need to be greatly abridged from their
present numbers, or they would soon exceed

83

the ratio of subsistence. The time occupied
in attaining maturity bears a direct proportion
to the period of existence in the mammalia ;
consequently, if life were prolonged beyond
its present limits, that time during which the
offspring of man is either helpless or very
dependent on the parents, would be also length-
ened, and the accidents of disease or other
casualties remaining the same, it is clear that
confusion, distress, and manifold calamities
would accrue to a rising generation. After
the attainment of maturity and of its accompa-
nying faculties, it is not clear that any thing
would be gained by the possession of these
for a longer period than is now allowed ; since we
know but too well that men, after a time, lose the
spirit of enterprise once engendered by the con-
sciousness of increasing or lately-acquire
powers, and fall into habits of action which
they are unwilling to abandon, but which
do not advance the resources of the species
beyond a certain limit. Hence the advan-
tage of their giving way to others, to whom
they can commit their knowledge, and who,
by their unworn energy, will advance it fur-
ther. Life is sufficient for all its purposes
if well employed,” was well observed by Dr.
Johnson; and what follower of medicine can
forget that the immortal sage of Cos, by the
example which he afforded in his well-spent
life, disarmed his own antithesis of its woful

point: 6 Bios Beads, 4 O8 réxyn ware;

BIBLIOGRAPHY.—Lord Bacon, Historia vite et
mortis. Pollich, Diss. de nutrimento, incremento,
statu, et decremento corp. hum, 4to. Strasb. 1763.
Ploucquet, Diss. sistens ztates humanas eorumque
jura, 4to. Tubing. 1778 ; (Recus in Frank Delect.
Opuscul. vol. vii.) Daignan, Tableau des varietés
de la vie hum. 2 vol. 8vo. Par. 1786. Rush, Med.
inquiries, vol. iv. Esparron, Ess, sur les ages de
Vhomme, Thes. de Paris, an. xi. Ranque, Des
prédominances organiques des différens ages, Thes.
de Par. 1803. Wesener, Spec. hist. hominis varias
ejus periodos, &c. sistens, 8vo. Kraberg. 1804.
Luce, Grundriss der Entwickelungsgeschichte des
menschlichen Korpers.8vo. Marburg, 1819, Burdach,
Die Physiologie als Erfahrungswissenschaft, 8vo.
Leipz. 1803. Renauldin, Dict. des Sc. Méd. art.
‘Age.’ Rullier, Dict. de Méd. art. ‘ Ages.” Begin,
Dict. de Méd. et Chir. Prat. art. ‘Age.’ Roget,
Cyc. of Pract. Med. art. ¢ Age.’ Copland’s Dict.
art. ‘ Age.” Also the anatomical and physiological
systems of Adelon, Beclard, Bichat, Bostock, &c.

&e. &e.
(J. A. Symonds. )

ALBINO. (Syn. Albinismus, leucopathia, leu-
cethiopia).—This term, as employed in phy-
siology, appears to have been first used by the
Portuguese* to designate a peculiar condition
of the human body, which was occasionally
observed among the negroes in the western
parts of Africa. It consists in the skin and
the hair being perfectly white, while in the

® Vossius, de Nili origine, cap. 19. p. 69; see
also Ludolf, Hist. Aithiop. Com. lib. i. cap. 14,
No. 100. p. 197. The name by which the African
Albinoes are known among their countrymen 1s
Dondos: by the French they are frequently termed
Blafards. :
G

34 ALBINO.

form of the features and in all other respects
the individuals in question exactly resemb‘e
the negro race. Another striking peculiarity
of the Albino is the state of the eye, which is
of a delicate pink or rose colour ; it is likewise
so sensible to light as to be unable to bear the
ordinary light of the day, while in the evening,
or ina dark shade, its functions a;pear to be
sufficiently perfect. We learn from Wafer,
who accompanied Dampier in one of his voy-
ages, and who relates his adventures in crossing
the Isthmus of Darien, that Albinoes are not
unfrequently found among the inhabitants of
this district.* We are also informed by various
travellers and naturalists that they are often
met with in some of the oriental isles, more
especially in Java and Ceylon;+ in all these
cases exhibiting the peculiar appearance of the
skin, hair, and eyes, while, in other respects,
they conformed to the external and physical
characters of the people among whom they are
found. The same circumstance occurs in this
country and in the other parts of Europe, al-
though, if we are to place any confidence in
the accounts of travellers, the Albino is much
more frequently met with in tropical climates,
especially in the western parts of Africa, and
in Darien, than in the more northern regions.

* Wafer’s New Voyage, p. 134..8; Buffon, Hist.
Nat. t. iii. p. 500; Wood’s Trans. v. iii. p. 419, 10;
Pauw, Recherches sur les Americains, par. 4,
sect. 1. t. ii. p. | et seq.; Raynal, Hist. des Indes,
t. iil. p. 288. The earliest account which we have
of the South American Albinoes is by Cortez, in
the narrative of his conquest of Mexico, which he
transmitted to Charles V. In describing the palace
of Montezuma, among other objects of rarity or
curiosity which were found in it, he says, ‘¢ In hujus
palatii particula tenebat homines, pueros, foemi-
nasque a nativitate candidos in facie, corpore, ca-
pillis, superciliis, et palpebris.”” De Insnlis nuper
inventis narrat., p. 30 of “ Nar. Sec.;” see also
Clayton, in Manch. Mem. v. iii. p. 261 et seq.

+ Buffon, t. iii. p. 399 and 415: Wood’s Trans.
Vv. lii. p. 328, 9 and 344. We have not been able
to procure the “‘ Voyages de Legat,” which is re-
ferred to by Buffon and others, as containing the
original account of the Albinoes, or, as they have
been termed, Chacrelos, of Java. With respect to
the Bedas of Ceylon, as originally described by
Ribeyro, Hist. de Ceylon, ch. xxiv., and more
lately by Percival, Account of Ceylon, ch. 13, and
by Cordiner, Desc. of Ceylon, v. i. c. 4, it seems
evident that they are not to be considered as Albi-
noes. The only remark which Ribeyro makes on
their physical character is, ‘‘ Ils sont blancs comme
des Européens, et il y a méme des roux parmi
eux,” p. 178. : Percival, who saw some of them,
states that their complexions are fairer and more
inclined to a copper colour, than those of the other
inhabitants ; while all that is said by these writers
respecting their habits and modes of life indicates
that they are a distinct race or tribe. The term
Beda, or Badah, appears to be a corruption of
Vaddah, or Veddah, which Knox informs us is the
name of the aborigines of the island; Account of
Ceylon, p. 61; see also Brown, in Brewster’s
Encyc. art. *‘ Ceylon,” p. 704; Cordiner and Per-
cival, ut supra. .

t Vossius and Ludolph, ubi supra; Argensola,
Conquist. de las Islas Malucas, lib. ii. p. 71,
speaks of Albinoes as not uncommon in these islands;
De la Croix, Rélation de |’Afrique, par. ili. liv. ii.
sect. ii, §. 13, ** Albinos, hommes blancs, ou

We meet with a few scattered remarks in the —
writ:ngs of the ancients, which render it evident
that this peculiar state of the human ~ had
falien under their notice. We have the follow-
ing sage in Pliny: “Idem” (Isigonus
Niceeensis) “ in Albania gigni quosdam glauca
oculorum acie, e pueritia statim canos, qui
noctu plus quam interdiu cernant.”* The same
circumstance is referred to by Aulus Gellius :
“ .... in ultima quadam terra, que Albania
dicitur, gigni homines, qui in pueritia canescunt,
et plus cernunt oculis per noctem, quam
inter diem ;”+ and by Solinus: he says that the
Albanians “albo crine nascuntur ;” “ glauco
oculis inest pupula, ideo nocte plus quam die
cernunt.”{ Pliny, in speaking of the inhabi-
tants of a certain district in the interior of
Africa, names them Leucethiopes ;§ and, as it
has been supposed that in this passage he
referred to the Albinoes, the term has been
applied to them by some eminent modern
naturalists ;|| but it appears more probable that
the Leucethiopes were a tribe of negroes
whose complexion was rather less dark than that

Mores blancs,” informs us that they compose a
considerable body of attendants at the court of the
king of Loango; the same statement is made by
Ludolf, ubi supra, and by the author of the Hist.
Gén. des Voyages, t. vi. p. 200 et seq.: Bowdich,
Mission to Ashantee, p. 292, observes, that the
king had at his court ‘* nearly one hundred negroes
of different colours, through the shades of red
and copper to white;” he adds that they were
“« generally diseased and emaciated ;” some of
these were probably Albinoes. Cook, in his first
voyage, saw six Albinoes in the small population
of Otaheite, v. ii. p. 188; in his second voyage
he saw one in New Caledonia, v. ii. p. 113, 4;
and in his third voyage, he met with three in the
Friendly Isles, v.i. p. 381, 2. These, it may be
remarked, must have belonged to the Malayan
variety. See also Winterbottom, Account of Sierre
Leone, v. ii. p. 166 et seq.; Stevenson, in
Brewster’s Encyclopedia, art. ‘* Complexion,”
p- 41, 2; Bory St. Vincent, L’Homme, t. ii.
$. “* Hommes Monstreux,” p. 143-7; also in Dict.
Class. d’Hist. Nat. art. ‘* Homme,” p. 166 et
seq.; Renauldin, in Dict. des Scien. Méd. art.
«« Albino ;” Lawrence’s Lect. p. 287; Is. St. Hi-
laire, Anom. de l’Organization, t. i. par. ii. liv. iii.
ch. i. p. 296, 314, 5, and art. ‘* Mammiféres,” in
Dict. Class. d’Hist. Nat. p. 113. Some of the
earlier writers did not hesitate to affirm, that they
were confined to the offspring of negroes, Monge,
Journ. Phys, 1782, p.401 et seq. Suppl. We
have no very distinct account of Albinoes among
the Chinese and Mongols, but they appear to be
as frequent among the Malays and native Americans
as among the AXthiopians. :
* Hist. Nat. lib. 7. cap. 2. See the note of
Cuvier, in his edition of 7th..1lth books of ©
Pliny, t. i. p. 18. _
+t Noct. Attic. lib. 9. cap. 4. i.
¢ Polyhistor, cap. 15. p. 25. See the remarks —
of Saumaise, Exerc. Plin. p. 134, and of Pauw,
t. ii. note in p. 13. ed
§ Lib. 5. cap. 8. We also find the same term
Pomponius Mela, lib. 1. cap 4, and in Ptole
Geog. lib. 4. cap. 6; but it is not accompanied by
any description of the people so designated.
Lakisong others by Blumenbach, Gen. hum.
var. §78. See Is. St. Hilaire, p. 297, note. —
may remark that the term is objectionable, as i
cating that the Albino is confined to the Athi
variety. :

of the Africans generally.* It has been like-
wise supposed that Celsus alluded to the Al-
bino, when he speaks of a peculiar condition
of the skin under the name of Leuce;+ but
this appears to be a morbid cutaneous affection,
and to have no reference to the subject now
under consideration.

From the number of Albinoes which were
supposed to exist in certain countries, as well
as from the marked peculiarity in their ap-

nce, an opinion was long entertained that
they formed a distinct race or variety of the
human species,{ originating in some unknown
cause, and bearing the same relation to the
other inhabitants of the countries in which
they are found that the acknowledged varieties
of the human species bear to each other. But
this opinion, although sanctioned by high
authority, may be considered as decisively
disproved by the well-ascertained fact, that
Albinoes are born of parents who do not possess
this characteristic peculiarity of the skin, hair,
and eyes.§

Although Albinoes are of comparatively rare
occurrence in Europe, yet we have had a suffi-
cient number of examples to render us per-
fectly familiar with the appearance which they
present, and with the precise nature of the

* See the note of Hardouin in loco, Valpy’s ed.
p. 1285, Le Maire’s, t. ii. p. 438; also the remark
of M. Marcus in M. Ajasson’s Trans. of Pliny,
t. iv. p. 185. Itis, perhaps, to this lighter coloured
negro, rather than to the proper Albino, that we
must refer, in part at least, the accounts which are
given by travellers of the great number of white
Africans that have been collected in certain situa-
tions. We may remark that all accounts of Albi-
noes that are given in general terms only, should be
received with a certain degree of caution, unless the

culiar state of the eye is distinctly noticed.

umboldt ,remarks that the missionaries, when
they ,met with any Indians that were less
black than ordinary, were accustomed to call them
white; Pers. Nar. by Williams, v. iii. p. 287 et
| seq. See Prichard, in Medical Cyclop. Art. “‘ Tem-
_ perament,” p. 163.
+ De Medicina, lib. 5. cap. 28. § 19.
4 $ This appears to have been the case even with
Haller, El. Phys. xvi. 4. 13. p. 492. Voltaire main-
tains this hypothesis, Essai sur les mceurs, Qiuvr.
_ t. xiii. Introd. and p. 7,8. Buffon inclines to it;
_ bat his opinion on this point is not decided or
uniform, t.iii. p. 501. See Is. St. Hilaire, p. 295.
__ § In addition to the authors already referred to,
_ we have a case of this kind by Helvetius, Hist.
_ Acad. Sc. 1734, p.15..7. The Albiness described
_ by Buffon was born of black parents: see also
_ Castillon, in Berlin Mem. 1762, p. 99..105; Dic-

_ quemarc, Journ. Phys. 1777, p. 357... 0, and 1788,

p- 301 et seq. ; Hist. Acad. Scien. 1744, p. 12, 3;
and Maupertuis, Ven. Phys. p. 135 et seq. : Jeffer-
son, Notes on Virginia, p. 103..5, mentions an in-
_ Stance of three Albino sisters born of black parents ;
_ two of these had black children’; Firmin, Descrip. de
Surinam, t. i. p. 153, 5; Goldsmith’s Anim. Nature,
t.i. p. 452, 3; Brue, Hist. des Voyages, t. iii.
p- 370, 0. See on this point Is. St. Hilaire, p. 303.
We have a decisive proof that the peculiarity of
the*®Albino is merely accidental and individual,
and does not constitute a distinct variety, in the
State of the offspring of an Albino and a black
hegro, which is not intermediate between the two,
as in the case of the Mulatto; Hunter, on the
Anim, Gicon. p. 248; Is. St. Hilaire, p. 305...7.

ALBINO.

85

circumstances which characterize them.* The
skin is of a milky whiteness, without the
slightest admixture of the brown or olive tint
which is found in the complexion of even the
fairest European female ; the hair is also per-
fectly white,t and is generally of a soft or
silky texture, while all the coloured parts of
the eye are of a delicate rose colour. We
are informed that the skin of the African and
American Albino is not only completely free
from any shade of brown or olive, but that it
is also devoid of the pink tinge which is found
more or less in the complexion of the European.
It would appear, likewise, that the skin of
the tropical Albino is frequently in a diseased
state, being covered with scales of a leprous
nature, and with a serous exudation, which
proceeds from the fissures or clefts that take
place in various parts of the surface.{

It has been a very general opinion, that be-
sides the peculiar state of the integuments, the
Albino possesses a general delicacy of habit
and constitution, and that he exhibits a defici-
ency even of mental power.§ For this latter
opinion there appears to be no sufficient foun-
dation, and with respect to the former we may
remark, that any general weakness of the phy-
sical frame, if it be actually found to exist, may
be probably referred, at least in some degree,
to the peculiar condition of the eyes and the
skin, which are not well adapted either to a

* We have a copious list of references in Blu-
menbach, p. 278..0, in Lawrence, p. 281..9, and
in Is. St. Hilaire, ut supra and §.5. One of the
earliest of what may be considered as the correct
descriptions is that of Buffon, Supp. t. iv. p. 559
et seq. ‘The descriptions of Blumenbach, §. 78,
and of Saussure, Voy. §. 1037... 1043, are par.
ticularly correct and characteristic: to this we may
add the more recent account of Is. St. Hilaire, t. i.
par. 2, liv. 3. ch. 1, §. 2 and 5. We are informed
by Ludolf, ubi supra, that the first modern writer
who distinctly mentions the Albino is Tellez.

+ Blumenbach particularly characterizes the
whiteness of the hair of the Albino as being ‘“¢ gilva,
cole cremoris lactis quodammodo comparanda,”
p- 275.

¢{ See Vossius, Ludolf, De la Croix, Cook’s First
Voyage, and Winterbottom, ut supra; Blumen-
bach, p. 274; Buffon, in Hist. Acad. Scien. 1760,
p- 17; St. Hilaire, p. 304, 5: Wafer, in his de-
scription of the white inhabitants of Darien, p. 134,
et seq., says that there is a white down on their
skin.

§ Wafer, p. 134-8; Buffon, t. iii. p.503 ; Wood’s
Trans. vol. iii. p. 420; Voltaire, t. xv. p. 269,70;
Pauw, t. ii. p. §: 10; Raynal, t. iii. p. 288; Du-
bois on the People of India, ch. xv. p. 199 et seq. ;
Firmin,t. i.p. 153..5; Dalin, in Amen. Acad. t. vi.
p- 74, note; Isert, Voy. en Guinée, ch. xv. p. 199
et seq.; Labillardiére, Voyage, t. ii. p. 141; Win-
terbottom, ut supra; Rayer, sur le Peau, t. ii.
p. 193 .. 203; Blandin, Dict. Méd. Chir. Prac, «Al-
binie ;” Breschet, Dict. de Méd. ‘* Albino;”
Sonini, in his edition of Buffon, t. xx. p. 355-6,
note. So far as regards the state of the intellect,
the charge is repelled by M. Sachs, who gives a
minute account of the peculiarity in his own person
and that of his sister; Hist. Nat. duor. Leucethio-

um. Jefferson informs us, that the Albinesses, of
which he gives an account, were ‘ uncommonly
shrewd, quick in their appehension and reply,”
p- 103-5.

86

bright light or to a high temperature, and there-
fore render the individuals less able to bear
pe to the weather, or to perform the
ordinary occupations of life. To the same
cause may be ascribed the morbid condition of
the skin, which, as was remarked above, occurs
not unfrequently in hot climates, and which is
not observed in the European Albino. Partly
from the circumstances stated above, and edt
from the idea of imperfection or defect, whic
is connected with their appearance, the tropical
Albino is generally regarded by his country-
men with a degree of compassion or even of
contempt ;* and hence is derived one of their
popular denominations, chacrelas, which is a
corruption of kakkerlakken, the Dutch name
for the cock-roach, as being, like those animals,
able to leave their haunts only in the evening.+
Besides the complete Albino, which we have
now described, there are occasional examples
of individuals, where the whiteness of the skin
exists in certain parts of the surface only, while
the remainder of the body is of its ordinary
colour.{ In the majority of cases the peculi-
arities which constitute the Albino are connate,
and continue during life without any change.
There are, however, some instances, where the
whiteness of the skin does not exist at birth,
but makes its appearance at a subsequent pe-
riod, generally by slow degrees, until the com-
plete Albino character is induced.6 When

* Vossius, p. 68, informs us that they are avoided
by the other negroes, as supposed to be diseased.
De la Croix says the negroes regard them as mon-
sters, and do not permit them to multiply, ut supra.
Dubois, p. 199 et seq. observes that they are named
lepers by birth, and that when they die their bodies
are not buried or burnt, but cast on dunghills. See
also Firmin, ubi supra.

+ Blumenbach, p. 277; Lawrence, p. 287; St.
Hilaire, p. 296.

¢ Phil. Trans. vol. xix. p. 781, and Lowthorpe’s
Abridg. vol. ii. p. 8; Buffon, t. iv. p. 565. tab. 2, et
p- 971, tab. 3; Arthaud, in Journ. Phys. 1789.'pt. 2.
p- 277,8; Rush, in Amer. Trans. vol. ii. p. 392 et
Seq. ; Gumilla, El Oron. Ilus. t. i. p. 109 et seq. ;
Ditto, Hist. de l’Oronoque, trad. t. i. p. 150 et seq. 5
Jefferson, p. 105; Blumenbach, § 48; Rayer, ut
supra; Is. St. Hilaire, p. 309 et seq. ; Isert, p. 156.
Bell, in Travels in Asiatic Russia, p. 217,8, saw
a number of persons with white spots on the skin,
but it seems probable that this was the effect of
some cutaneous disease. The partial Albino appears
to have been noticed by the ancients ; Lucian,
Prometh, t.i. p. 15.

§ Blumenbach, p. 276, says it is « semper con-
natus ;” see, also, Lawrence, p. 285. There are,
however, certain well authenticated cases, where
the skin of the negro has gradually changed ita co-
lour from black to. white ; sometimes the change
has been general, sometimes only partial ; Bates,
in Phil. Trans. vol, li. p. 175 et seq. 3 Gualtier, in
Journ. Phys. t.Ixx. p. 248 et seq.; Le Cat, sur le
Peau, p. 112 et seq.; Rayer, ut supra; Fisher, in
Manch. Mem. vol. v. p. 314 et seq.; Rush’s Re-
marks on the same, Amer. Trans. vol. iy. p- 289
et seq. In one of the four cases which are men-
tioned by Le Cat, the change of colour appears to
have been the ee of a severe burn or scald.
Besides the partial Albino, we have what has been
termed the imperfect Albino, where the peculiarit
exists in a certain degree only ; Is, St. Hilaire, §, ru
p- 312 et seq.

:

ALBINO.

once formed it does not seem that it-ever dis-
appears, or is even in any degree diminished,
nor have we any authentic accounts of its being _
removed by any constitutional change, either —
natural or morbid, or by external applications. —

Although, as has been stated above, this
peculiarity occurs in individuals, who did not
derive it from their parents, yet, like all those
deviations from the ordinary structure of the
body, which have been styled accidental varie-
ties, when once produced, it is disposed to
propagate itself by hereditary descent. There
are also certain individuals, who have a ten-
dency to produce it; so that even among the
few European Albinos, of which we have a
minute account, we have cases of its occurrence
in two or more members of the same family,
either as connected by parental descent, or by
collateral relationship.* We have no instance
on record of the offspring of a male and female
Albino.

The whiteness of the skin and hair, both
general and partial, is not confined to the hu-
man race; it is found in most, if not in all the
species of the mammalia, and in some of these,
as in the dog, the horse, and the rabbit, is the
subject of daily observation ;+ in most of them,
however, the peculiar state of the eye does not
exist. These white varieties, like other analogous
cases among the lower animals, when once
produced, are strictly hereditary, in which re-
spect they differ somewhat from the human
Albino.

Various opinions have been entertained by
physiologists respecting the nature of this pecu-
liarity, whether it should be considered as a
morbid affection,{ depending upon a diseased
state of the constitution, and also respecting
its immediate or efficient cause. The first of
these points may be regarded as a verbal con-
troversy, depending altogether upon our defi-
nition of morbid action; but we conceive, that
according to the ordinary definition of the term,
we should not consider it as a disease, but as a
connate deviation from the perfect structure of
the animal frame, not produced by an external
cause, and not removable by a remedial agent.
For a correct knowledge of its physical cause,
we are indebted, in the first instance, to an in-
genious conjecture of Blumenbach’s, who ac-
counted for the red colour of the eye, and its
extreme sensibility to light, by the absence of —
the pigmentum nigrum.§

ee

* See particularly Saussure’s account of the two
boys of Chamouni and Sachs’s Narrative ; also Blu-
menbach, p. 276 and 279, note ; Firmin and Jef
son ut supra ; Pauw, t. ii. p. 25; Bory St. Vince
L’Homme, 'p. 144, mentions an Albino of the th

297..'.9

$ “ Ad cachexias referenda videtur affectio
Blumenbach, p. 274; Is. St. Hilaire, §. 6, suppost
that there are two species of Albinism, one the ef
of disease, the other a-true anomaly; but we
ceive that the term is not correctly applied to
former state. ‘ae

§ Comment. de Oculis Leucethiopum, et D
Gen. Hum. var. §. 78. ‘ Ss

ALBINO.

This conjecture was shortly after verified by
Buzzi of Milan, who took advantage of an
opportunity which presented itself, of dissecting
_ the eye of an Albino, in which the pigmentum
- nigrum could not be detected.* He also ex-
amined the structure of the skin, which appeared
to be deprived of the rete mucosum, that part
of it in which its specific colour is supposed to
reside ; the hair was also found to be deficient
in its central coloured part.; Whether, in
these cases, the pigmentum nigrum of the eye
and the rete mucosum of the skin are absolutely
deficient, or are only deprived of their colouring
matter, so.as not to be detected by the eye, is a
ee on which different opinions have been
ormed by anatomists;{ perhaps, upon the
whole, we may be induced to consider the lat-

ter opinion as the most probable.
hat are the circumstances in the consti-
tution of the parents which should lead to this
culiarity in their offspring is entirely un-
nown, nor have any conjectures been formed
on the subject which can be considered as even
4 plausible.§ The hypothesis of Buffon, which
___ at one time obtained a considerable degree of
credit, that white is, as it were, the primitive
colour of nature, which, by various external
causes, is changed to brown or black, but which
the body has always a tendency to resume
under favorable circumstances,|| is completely
without foundation: nor does it appear that
we can explain it upon the principle, that do-
mestication and the habits of civilized life have
a tendency to produce a lighter shade of the
complexion, because we trace no connexion
between the supposed cause aud the effect,

* For some remarks “‘ on the colour of the pigment
of the eye,” and its effect on vision, as applicable
to the eye of the Albino, see Hunter, p. 243 + + 200 5
also Blumenbach, §. 51. ‘“‘ Capillorum cum cute
consensus,” and §. 53, “ Irides oculorum cum capil-

lorum colore consentientes.”
____# Sachs gives us a minute account of the analysis
_ of the hair of the Albino, compared with Vauquelin’s
ii alysis of hair in its ordinary state, from which it
appears that no iron could be detected in it.
_ _ ¢ Blandin, Dict. Méd. Chir. Prat. ‘« Albinée ;”
Rayer, §. 630.
_ __§ Mansfeldt is disposed to ascribe the production
‘of the Albino state to some shock given to the
_ foetus, by an impression made upon the mother ; it
is characterized asa ‘‘ cessation totale, momentanée
action cérébrale ;” Journ. Compl. t. xv. p. 250 et
- seq. Is. St. Hilaire essentially adopts this hypo-
thesis, ascribing the peculiar state of the skin to an
_ arrét de développement,” in consequence of which
_ the colouring matter is not formed at the requisite
period, p. 319,0. The idea, that it depends upon
omething peculiar in the seminal matter of the
‘rent, which was maintained hy Herodotus, Thalia,
101, and was controverted by Aristotle, Hist.
Animal. lib. 3. cap, 22, has been revived by Mau-
1is, Diss. 2, and by Pauw, t. i. p. 179, and t. ii.
_ p.21. Le Cat refers the colour of the negro to a pecu-
iar substance, which he names “‘ Athiope animal,”
_ which he supposes is contained in their fluids, ana-
_logous to the black inky matter of the cuttle fish ;
par. 2. art. 1; the absence of this substance con-
_ verts the negro into an Albino.
__|j T. iii. p. 502,3,; Wood’s trans. t. iii. p. 422.
_ We may remark that this speculation of Buffon’s is
isely the reverse of that of Hunter, p. 243 et

~~
a

~#p

-
i } he

Seq.

87

and because the production of the Albino is
complete in the first instance, and not brought
about by any gradual or progressive alteration.
It appears that we must come to the con-
clusion, that although the anatomical or phy-
sical cause of the peculiarity is ascertained, yet
that we are entirely ignorant of its remote
cause, or of that train of cireumstances which
leads to its production.* }

* «¢ The following cases have not been referred
to in the body of the article; Dela Nux, Hist.
Acad. Scien. 1744, p. 13; Camelli, Phil. Trans.
v. xxv, p. 2268; Duddell on the Eye, Suppl. to,
sect. ili. §,30 et seq.; Percival, Irish Trans. v. iv.
p. 97,8; Hunter, Anim. Gicon. p. 250, 1; Traill,
in Nich. Journ. v. xix, with an Add. by the editor ;
Mansfeldt, Journ. Compl. t.xv 3; Ansieux, in Journ.
Méd. de Corvisart, t. xiv, p. 263, 4.

For the following epitaph, which appears to have.
been written on an Albino child, we are indebted
to a literary friend, the Rev. Jos. Hunter.

** Upon Thomas, son of Ric. Elmhurst by Mar-
garet his wife, daughter to Ric. Micklethwaite :
whose promising parts, were interrupted by an early
death.

«* ... This boy no Albian was, yet gray hair’d

borne

Who saw old age and night as soon as morne.
His grave’s a cradle; there his God him lay’d
Betimes to sleep lest he the wanton play’d.

Bid him good night! i’th bed of dust sleep on
Until the morne of Resurrection.

*«« Anagram.
‘¢ Lo Earth misseth me, 1632.”
From the Church of Worsborough, Com. York.

BIBLIOGRAPHY.—Ansieux, in Journ. Méd. de
Corvisart, t. xiv. Argensola, Conquist. de las Islas
Malucas. Lond. 1609. Aristoteles, Opera a Du Val.
Par. 1619. Arthaud, in Journ. Phys. pour 1789.
Bates, in Phil. Trans. v. li. Bell’s Travels. Glas.
1763. Blandin, in Dict. Méd. Chir. Prac. ‘‘ Albinie.”’
Blumenbach, Gen. Hum. var. (ed. 3.) Gott. 1795;
Ditto, Comment. de Oculis Leuceth. Gott. 1786.
Bory St. Vincent, in Dict. Class. d’Hist. Nat.,
««Homme ;” Ditto, ’7Homme. Par. 1827. Bostock,
in Brewster’s Encyc. ‘‘ Albino.” Bowdich, Mis-
sion to Ashantee. Lond. 1819. Breschet, in Dict.
de Méd., «* Albino.”” Brown, in Brewster’s Encyc.,
** Ceylon.” Brue, in Hist. Gén. des Voyages, t. iii.
Buffon, Hist. Nat, (ed. 2). Par. 1750.; Ditto, by
Sonnini. Par. An. 8; Ditto, (trans.) by Wood.
Lond. 1812. ; Ditto, in Hist. Acad. Scien. pour 1766.
Camelli, in Phil, Trans. v. xxv. Castillon, in Ber-
lin Mem. 1762. Celsus, De Medicina, ab Alme-
loveen. L. B. 1730. Clayton in Manch. Mem. v. il.
Cook’s first voyage, ‘by Hawkesworth. ‘Lond. 1775.
Ditto, second ditto. Lond. 1777. Ditto, third ditto.
Lond. 1784. Cordiner’s Description of Ceylon.
Lond. 1807. Cortesius, De Insulis nuper invent.
Narrat. Colon. 1532. Dalin, Ameen. Acad. t. vi.
De la. Croix, Rélation de Afrique. Lyon. 1688.
De la Nux, in Hist. Acad. Scien. pour 1744. Dique-
mare, in Journ. Phys. pour 1777 and 1788. Dubois,
on the people of India, (trans.) Lond. 1817. Dud-
dell, on the eye, and Suppl. Lond. 1729. Firmin,
Descrip. de Surinam. Amst. 1767. Fisher, in
Manch. Mem. v. v. Gellius, Noctes Attice. Basil,
1565. Goldsmith’s Animated Nature. Lond. 1822.
Gaultier, in Journ. Phys. t. 1xx. Gumilla, El. Oro-
noco ilust. Madrid. 1745. Ditto, Hist. de 1’Oro-
noque (trad.) Avignon. 1758. Haller, Elem.
Physiol. Laus. 1757. Helvetius, in Hist. Acad.
Scien. pour 1734. Herodotus, by Beloe (3d. ed.)
Lond. 1812. Humboldt’s Pers. Nar. by Williams.
Lond. 1814. Hunter, on the Animal ae .
Lond. 1792. JIsert, Voyage en Guinée. Par. 17 3.
Jefferson’s Notes on Virginia. Phil. 1794. Knox's

88 ALBUMEN.

Account of Ceylon. Lond. 1681. Labillardiere,
Voyage. Par.8. Lawrence’s Lectures. Lond. 1819.
Le Cat, Traité de la Peau. Amst. 1765, Lowthorpe’s
Abridg. of Phil. Trans. (2d. ed.) Lond. 1716. Lu-
cianus 4 Grevio. Amst. 1687. Ludolf, Hist. Athiop.
comment. Franc, 1691. Mansfeldt, in Journ.
Compl., t.xv. Maupertuis, Venus Physique. Haye.
1746. Monge, in Journ. Phys. pour 1782. Pauw,
Recherches sur les Américains, Lond. 1760. Per-
cival’s Account of Ceylon. Lond. 1803. Ditto, in
Irish Trans., v. iv. Plinius, Hist. Nat. a Valpy.
Lond. 1826. Ditto, i Lemaire. Par. 1827. Ditto,
lib. vii... xi., a Cuvier. Par. 1827. Pline, Hist.
Nat. par Ajasson (trad.) Par. 1829. Pomponius
Mela, a Gronovio. L, B. 1782. Prichard, in Cy-
clop. of Pract. Med.,‘‘ Temperament.” Ptolemeus,
Geographia, a Bertio. Amst. 1618. Rayer, Traité
des maladies de la Peau. Par. 1826. Raynal, Hist.
des Indes. Neuch. 1785. Renauldin, in Dict. des
Sc. Méd., “« Albino.” Ribeyro, Hist. {de Ceylon.
Trev. 1701. Rush, in Amer. Trans., v. ii. and iv.
Sachs, Hist. Nat. duor. Leucethiopum. 1812. Sz.
Hilaire, ( Isid.), Anomalies de Organization. Par.
1832.5; Ditto, in Dict. Class. d’Hist. Nat., ** Mam-
miféres.” Saussure, Voyages dans les Alpes. Ge-
nev. 1787. Solinus, Polyhistor, cum Sualmatii,
Exerc. Plinian. Traj. ad Rhen. 1689. Stevenson,
in Brewster’s Encyc. ‘‘ Complexion” Traill, in
Nicholson’s Journ. v. xix. Voltaire, GQiuvres. Par.
1819. Vossius, de Nili Origine. Hag. Com. 1666.
Voyages, Hist. Gén. des, Haye, 1747. Wafer’s
New Voyage. Lond. 1699. Winterbottom’s Account
of Sierra Leone. Lond. 1803.
(J. Bostock.)

ALBUMEN, (Fr. Albumine, Germ. Eyweis-
sstoff, ) is one of the most important proximate
principles of animal bodies; it is the leading
ingredient of the blood, of many of the secretions,
and of muscular fibre, cartilage, and membrane :
the white of egg (whence the generic term albu-
men) presents it in considerable purity, and it
is from this source, and from the serum of the
blood, that we chiefly obtain it for the purposes
of experiment. In this article we shall describe
the leading properties of albumen; and in
others, refer to its principal modifications.

The white of egg may be regarded as a
combination of albumen with water; it con-
tains small quantities of saline substances,
which are inseparable in its liquid state. When
it is evaporated at a temperature below 120°,
it dries into a brittle, shining, transparent sub-
stance of a pale yellow colour, inodorous and
tasteless. Its ultimate constituents, exclusive
of saline matters and a trace of sulphur, are
carbon, hydrogen, nitrogen, and oxygen; of
these the relative proportions have been deter-
mined by Gay Lussac and Thenard, who
analysed the white of egg dried at 212°; and
by Dr. Prout, who employed the dried serum
of slightly inflammatory blood ; the following
table shows its theoretical composition as con-
trasted with these experimental results :—

Atoms. Equivs. Theory. G, Lussac. Prout.
Carbon..8 48 51.61 52.883 50.00
Hydrogen 7 7 7.53 7.540 7.78
Nitrogen 1 14 15.05 15.705 15.55
Oxygen 3 24 25.81 23.872 26.67

1 93 100.00 100.000 100.00

- White of egg, when heated to about 150°,
coagulates, that is, it becomes a white, translu-
cent, and somewhat elastic substance, which,
when cautiously dried, shrinks up and assumes —
the appearance of horn, becoming tough, yel-
lowidl and insoluble in water. Two parts of
white of egg and one of water entirely co-
agulate when duly heated; equal parts remain,
under the same circumstances, semi-fluid ; a.
mixture of one part of white of egg and ten of
water becomes opaque, but is not coagulated 5
and a milkiness is perceptible when the al-
bumen only forms a thousandth part of the
solution.* “Fresh-laid eggs, and those which
have been oiled upon the surface do not per-
fectly coagulate when put into boiling water, in
consequence, probably, of the dilute state of
the albumen. One hundred parts of the fresh
albumen of the egg, when carefully evaporated
in vacuo, leave a residue = fifteen parts. One
hundred parts of the coagulated white of a
duck’s egg (dried in vacuo with sulphuric
acid) leave 13.65 parts, which, steeped in
water, acquires its original appearance, but in
four days only took up 68 of water, though it
had lost 86.35.+

When albumen is made part of the voltaic
circuit, it presents appearances dependent upon
the power used, which, when considerable,
excites so much heat as to coagulate it; but
with a feeble power and the poles sufficiently
distant, coagulation ensues most plentifully at
the negative platinum wire; a coagulum also
forms at the positive wire, where acid is also
sparingly evolved. These phenomena are much
interfered with by the evolution of gaseous
matters at the respective poles, which occasion

a froth, and the appearance of more extensive ~

coagulation than actually occurs.

When coagulated white of egg is boiled for
several hours, it shrinks up and becomes har-
dened, communicating traces of animal matter
to the water. Heated by high pressure steam
in a copper digester to 400°, it blackens the
interior of the vessel, and dissolves, leaving
a small residue of unaltered albumen. The
solution is brown, and has the odour of boiled
meat (from osmazome?). This action deserves
turther investigation.

White of egg soon runs into putrefaction,
and evolves sulphuretted hydrogen. The se-
rum of blood kept for two years in a well-
stopped phial, blackened its interior, and be-
came a stinking, pale, yellow liquid, still co-
agulable by heat, and containing hydro-sul-
phate, carbonate, and acetate of ammonia, and
a fetid volatile matter: a portion of yellowish
white purulent-looking matter, containing un-
decomposed albumen, remained at the bottom

of the phial. Coagulated white of egg, even 4

under water, long resists putrefaction.

* Bostock, Nicholson’s Journal, vol. xiv. and 4

Medico-Chirurgical Transactions, vol. 1. and ii.
+ Chevreul, |Mém. du Museum vii. 180. Ann. —
de Ch. et Ph. xix. 46. :

¢ Gmelin, Handbuch der Theorctischen Chemie, —

ii. 1053. 3rd ed. Frankfort, 1827.

ALBUMEN.

One hundred parts of dried white of egg,
subjected to destructive distillation, yielded
carbonic acid, carburetted and sulphuretted
hydrogen, prussic acid, carbonate of ammonia
partly in solution and partly sublimed, stinking
volatile oil, and 14.9 of spongy difficultly com-
bustible carbon, which, by incineration, left
2.21 of ash composed of carbonate of soda,
phosphate of soda, and phosphate of lime,
( Hatchett.)

Nitric acid, dropped into a solution of albu-
men, forms a white, flaky precipitate, which is
more or less abundant according to the state
of dilution of the solution, and which is soluble
in ammonia and potash. When coagulated
white of egg is kept for some weeks in very
dilute nitric acid, it acquires a yellow colour,
and if digested in boiling water it dissolves,
and has acquired the properties of gelatine,
and is precipitated by tan and muriate of tin.
Hatchett.)* Cold nitric acid sp. gr. 1.25,
gradually tinges coagulable white of egg of a
yellow colour, dissolving a little of it, and
forming malic acid, with the evolution of nitro-
gen; its surface becomes tallowy, and in
twenty-four hours it falls into a pale yellow
powder, which is acid and composed of nitric,
nitrous, and malic acids with albumen; when
thoroughly washed with water, it becomes more
neutral and of an orange colour, still reddening
litmus, and remaining insoluble in water, but
soluble in caustic potash.t When coagulated
white of egg is digested in hot nitric acid,
nitrogen, nitrous gas, carbonic acid, and prussic
acid are formed, and a dark yellow solution
obtained, which is precipitated by the addition
of water and ammonia, and which contains
malic and oxalic acids, bitter matter, and fat.
(Hatchett.)t

Sulphuric acid is a less powerful precipitant
of albumen than nitric acid. Dilute sulphuric
acid dropped into an aqueous solution of
albumen occasions a precipitate which is so-
luble in excess of acid; ferrocyanate of po-
tassa throws it down. When coagulated albu-
men is digested in sulphuric acid, very slightly
diluted, it yields a deep crimson solution.§ Coa-
gulated serum digested in sulphuric acid diluted
with six parts of water, converts it into acid
sulphate of albumen, which, when edulcorated
with cold water, becomes more neutral, and
is soluble in warm water, forming a gelatinous
solution, which is precipitated by sulphuric,
muriatic, and nitric -acids, and by the alkalies.
(Berzelius.)|| Coagulated white of egg digested
in hot sulphuric acid becomes carbonized
without forming artificial tan. (Hatchett.)

Whena solution of recently fused phosphoric
acid (pyro-phosphoric acid) is added to solution

* Phil. Trans. 1799.

t Berzelius Lehrbuch der Thier. Chemie, p. 38.
Wohler’s Translation. Dresden, 1831.

¢ Phil. Trans. 1799.
- § According to Raspail, when sugar is previously
dissolved in the sulphuric acid, the albumen is co-~

_ lonred purple, which is deeper in proportion as the

acid and sugar are in greater quantity.
|| Lehrbuch der Thier, Chemie.

™

89

of albumen, it occasions an abundant pre-
cipitate: the acid gradually loses this property,
and again acquires it by fusion and ignition.
(Berzelius.)

Muriatic acid occasions a precipitate in al-
buminous solutions, and entirely throws down
the albumen when aided by heat; but the
precipitate is soluble in excess of acid, and
in ammonia and potassa. A muriated albu-

“men may be formed in the same way as the

sulphate. (Berzelius.) Coagulated egg-albu-
men digested in muriatic acid gradually ac-
quires a purple colour. (Hatchett.) Albumen
which has been precipitated by muriatic acid,
often becomes reddish when collected and ex-
posed upon a filter.

When coagulated seralbumen is digested
in acetic acid, it becomes soft and transparent,
and, aided by a gentle heat, dissolves with the
evolution of a little nitrogen. This solution
is precipitated by the alkalies, but a slight excess
again renders it clear: it is also precipitated by
sulphuric, nitric, and muriatic acids, and by
ferrocyanate of potassa. When this acetic so-
lution of albumen is evaporated, it leaves a
transparent sour residue, soluble in warm water
acidulated by acetic acid. Sismse ne

Albumen is slowly soluble in liquid ammo-
nia. In solution of potassa it becomes gelati-
nous, and yields a pale yellow green solution,
precipitable by acids and alcohol, and by acetic
acid. Heated in liquid potassa, albumen
evolves ammonia.

Alcohol and ether coagulate ovalbumen, but
pure ether (free from alcohol) does not co-
agulate seralbumen. (Gmelin.) When serum
is shaken with ether, it soon separates upon
the surface, holding fatty matter in solution.
(Gmelin.) Coagulated serum digested in al-
cohol or ether yields a solution of fatty
matter.

Coagulated ovalbumen, when long boiled in
water, becomes bulky and falls into pieces, and
a small portion is dissolved: the filtered so-
lution, evaporated at 212°, leaves a pale brown
film, and is alkaline ; it is rendered turbid by
mineral acids, acetic acid, and tincture of
galls, and by many metallic salts.

When albumen which has been cautiously
dried at a low temperature (without coagula-
tion) is triturated with four parts of water,
it yields a solution resembling fresh al-
bumen.

A solution of the white of an egg in a pint
of water occasions no precipitate in lime, bary-
tic or strontia water, nor in solution of sulphate
of lime. Some of the neutral salts render
it more or less turbid, and it is copiously
precipitated by solution of alum. Nitrate,
acetate, and subacetate of lead are precipitated
by albuminous solutions. One part of fresh
ovalbumen in 2000 of water, or one of dried
albumen in 10,000 of water is rendered turbid
by subacetate of lead. A four-hundredth part
of liquid, ora two thousandth of solid albumen
is precipitable by corrosive sublimate. (Bos-
tock.) The precipitate is blackened by potassa,
and is probably a compound ef muriate ofalbu-

90

men and calomel. Nitrate of silver, muriate
of gold,and of platinum, also precipitate albumi-
nous solutions. These precipitates are mostly
triple compounds of acid, albumen, and oxide,
and several of them are redissoluble in excess
of liquid albumen.

Albumen is precipitated by tannin in the
form of a yellow viscid combination. Water,
holding a thousandth part of solid or a two-
hundredth of liquid ovalbumen, becomes tur-
bid after some hours by the addition of a
solution of galls containing 2.5 per cent. of
solid matter. (Bostock.)

The above are the principal chemical pro-
perties of liquid and solid albumen as obtained
from the egg and from serum of blood ; several
of their modifications will be noticed under
other heads, such as Fisrine, Mixx, Bixsz,
&e.

The cause of the coagulation of albumen is, in
many cases, obscure and even inexplicable. It ap-
pears possible that the acids by which it is co-
agulated enter into combination with it so as to
form insoluble compounds; the same change pro-
bably happens with certain metallic salts, and
with tan; its coagulation by alcohol has been
ascribed to the abstraction of water. Having
remarked the copious coagulation of albumen
at the electro-negative pole in the voltaic cir-
cuit, I was induced to ascribe the fluidity
of albumen to combined soda, the evolution
of which seemed to cause its solidification, and
it appeared possible that the acids and even
alcohol might also occasion coagulation by the
abstraction of soda; and that its more enigma-
tical coagulation by heat only, might be as-
scribed to the transfer of soda from the albu-
men to the water. It has been objected to
this statement that the addition of alcali to
coagulated albumen does not reproduce liquid
albumen, and that acetic acid causes no co-
agulation ; but when albumen is once coagu-
lated, its properties are essentially modified,
and acetic acid, or even acetate of soda appear
to form soluble compounds with it. (Gmelin.)
Dr. Turner* supposes that albumen combines
directly with water at the moment of being
secreted, at a time when its particles are in
a state of minute division ; but as its affinity for
that liquid is very feeble, the compound is
decomposed by slight causes, and the albumen
thereby rendered quite insoluble. The or-
ganization of albumen may certainly be con-
cerned in its singular properties with respect to
many coagulants ; there are several albuminous
fluids, which we shall hereafter refer to, which
contain globules resembling those of the blood.
In the voltaic coagulation of albumen, that
which separates at the positive pole contains
-globules, which, under the microscope, resem-
ble the blood-globules deprived of their co-
louring matter.+

The readiest tests of the presence of albumen
in fluids are its coagulation by heat, alcohol,

* Elements of Chemistry, 4th ed. 868.
+ Prevost et Dumas, Ann. de Chimie et Physique
xxiii. 52.

AMPHIBIA.

and acids; when it is too dilute for such —
detection, it may be subjected to voltaic elec-
tricity, or tested by corrosive sublimate, or
by ferrocyanate of potassa; the alcali should,
in the latter case, be previously neutralized
by acetic acid. It would appear, from Orfila’s
experiments, that white of egg is an antidote
to the effects of corrosive sublimate when taken
into the stomach, and that, if administered in
sufficient quantity immediately after the recep-
tion of the poison, it prevents the progress
of the symptoms. The white of one egg
appeared sufficient to render four grains of the
poison ineffective.

The readiness with which some metallic
oxides are received into the system may per-
haps be ascribed to their affinity for albumen,
with which some of them form compounds not
easily decomposable, and in which the metallic
oxide cannot be detected by the usual tests,
till they have been subjected to heat sufficient
to decompose the organic matter. Mercury
and silver are thus, in certain cases, detected in
the secretions and excretions.

(W. T. Brande.)

AMPHIBIA.-—(Augis, utrinque, Bros, vita.
Fr. Amphibies. Germ. Amphibien. Ital.
Amphibie.) A class of vertebrated animals,
hitherto almost universally considered as an —
order of Reprirxi1a, constituting the Batrachia
of the later erpetologists. To the retention
of the latter appellation, as derived from the
Greek name of a single form of the group,
and as bearing no reference to any character
either of structure or of habit, there is an
obvious objection. The term Amphibia is
therefore here adopted, as designating one of
the most striking peculiarities of the class;
namely, the change which takes place at an
epoch of their life, more or less advanced,
from an aquatic respiration by branchie to an
atmospheric respiration by true lungs, and
an equivalent and consequent alteration in
their general structure and mode of life.

The Amphibia may be characterized as
“ vertebrated animals, with cold blood, naked
skin, oviparous reproduction, and most of them
undergoing a metamorphosis or change of con-
dition, having relation to a transition from an
aquatic to an atmospheric medium of respi-
ration.”

These characters, by many of which the am-
phibia are distinguished from the reptilia, are
sufficiently determinate and important to justify
our considering them as a distinct class, ac-
cording to the generally received principles of
zoological arrangement ; notwithstanding most —
even of the modern writers'on the subject have
retained them as merely an order of reptilia.
But it will also be seen that if in the adult state _
they approach the reptilia in many points of —
their general structure, their organization, during —
the early and imperfect condition of the tad-
pole, partakes no less of that of fishes.
an osculant or intermediate form, connecti
two others of higher typical importance, it m

be, certainly of greater extent, and consisting ;

ES ee ee a

AMPHIBIA.

of groups having more striking distinctive cha-
racters, there is not, perhaps, a more interesting
and satisfactory instance in the whole range of
the animal creation than is afforded us in the
class of amphibia: a circumstance which can
only be fully appreciated by following out the
structure of each system of organs, first as it
exists temporarily in the tadpole, and ultimately
in its permanent condition in the perfect animal.

The class has been variously divided into
groups according to the different views of the
naturalists by whom they have been arranged.
The division adopted by many zoologists of
the conan day, according to the mere presence
or absence of the tail in the perfect state, is
not only liable to the objections which belong
to all merely dichotomous arrangements, but
appears to be far less natural and less consistent
with the physiological characters of the groups
than that which may be derived from the
absence or presence and the duration of the
branchiz. us the frogs and toads, which
in the adult state have not the vestige of a tail,
and the salamanders and tritons, which retain
that organ through life, all agree in the early
apie of branchiz, which are subsequently
ost and replaced by true lungs, and in un-
dergoing consequently a total change in the
medium of their respiration; whilst the pro-
teus and the siren retain their branchie, with
lungs, (rudimentary at least,) and probably
throughout life possess synchronously the two-
fold function of aquatic and atmospheric re-
Spiration. The amphiuma and menopoma have
not as yet been observed to possess branchie
at any period of their existence, though further
observations are necessary to warrant the con-
clusion of an absolute non-existence of a meta-
morphosis in these genera.

It appears to me that no one arrangement
hitherto given sufficiently distinguishes the
different forms; and I venture to propose the
following modifications as more consistent with
the diversities of structure in the different

groups.
Class AMPHIBIA.

Order 1.—AmpuIpNEeuRTA.

Body elongate, formed for swimming. Feet
either four, or two anterior only. Tail com-
pressed, persistent. Respiration aquatic by
means of branchie, throughout life, co-existing
_ with rudimentary lungs. Branchie external,
_ persistent. Eyes with palpebre.

__ Genera, Proteus, Siredon, Menobranchus,
Siren, Pseudobranchus.

Order 2.—Anoura.

. Body short and broad. Feet during the tad-
_ pole state wanting ; afterwards four, the hinder
_ ones long and formed for leaping. Tail before
__ the metamorphosis, long, compressed ; after-
_ wards totally wanting. Ribs wanting. Ver-
_ tebre few and anchylosed. Tympanum open.
Respiration at first aquatic by branchiz ; after-
‘wards atmospheric by lungs. Branchiz at first
external, but withdrawn within the chest before

91
the metamorphosis. Impregnation effected ex-
ternally during the passage of the ova.

Genera, Rana, Hyla, Ceratophrys, Bufo,
Rhinella, Otilopha, Ductylethra, Bombinator,
Breviceps.

Order 3.—Urope.a.

Body long, slender. Feet always four. Tail
long, persistent. Ribs very short. Respi-
ration at first aquatic by external branchie,
afterwards atmospheric by cellular lungs. Ver-
tebre numerous and moveable. Tympanum
concealed. Impregnation internal.

Genera, Salamandrina, Salamandra, Molge.

Order 4.—ABRANCHIA.

Body long, formed for swimming. Feet four.
Cranium solid. Tail compressed. Respi-
ration by means of lungs only: branchie none.
No metamorphosis known.

Genera, Menopoma, Amphiuma.

Order 5.—Apropa.

Body elongate, slender, anguiform. Feet
none. Tail very short, almost wanting. Lungs
one larger than the other. (The existence of
branchiz at any period of life unknown.) Ribs
very short. Sternum wanting. Ears concealed.
Impregnation unknown, probably internal.

‘Genus, Cecilia.

I. Osteology.—The changes which take place
in the habits and formation of these animals,
in their passage from the tadpole or pisciform
state to their adult and permanent condition,
are not confined to any one system of organs
or of functions. The skeleton, the organs of
motion, of sensation,and of digestion are not less
the subject of these changes than those of
respiration and circulation: it will, therefore,
be necessary, in treating of each system of
organs, to describe not merely their structure
in the perfect state, but the less advanced
grade of organization from which they emerge
in passing from the condition of a fish to that
of a reptile.

In the adult state, however, they are found
to vary considerably in the form and composi-
tion of the skeleton, according to their habits,
and to the existence or absence of a tail. The
principle of compensation, or, in other words,
the extreme developement of one set of organs
at the expense of another, which is so often
seen to take place in every form of animals,
is here strikingly illustrated. In the frogs,
whose movements on land, from their feeding
chiefly on terrestrial prey, are necessarily ex-
tensive, we find the hinder legs developed to
an extraordinary degree, for the purpose of
enabling them to take enormous leaps, by
which they not only seek or pursue their prey
at a distance from the water, but rapidly
escape from danger, and rapidly regain their
place of refuge in the nearest pond or rivulet.
As it is evident that a long tail and a generally
elongated body, with a flexible spine, would
be not only useless but inconsistent with these
habits, we find these animals absolutely tail-

92

less, the body contracted longitudinally into
as short a space as possible, the vertebra very
few, and anchylosed or soldered together into
a single immoveable piece, and wholly devoid
of ribs.

On comparing with this formation, on the
other hand, the extensive developement of
the tail, the long flexible body, and gracile
form of the newts or aquatic salamanders,
and reflecting upon the obvious object of this
structure in facilitating their motions in the
water, we should hardly be prepared to find
that the extraordinary extension of the hinder
exitemities in the frogs, the primary object of
which is to afford the great powers of leaping
just alluded to, is made subservient also to
their aquatic life, by enabling them to swim
with great facility, aided by a web of skin
extending between the toes of the hinder
feet.

Now as we shall hereafter see, when treating
on the respiration of these animals, that the
occasional presence of water, and its applica-
tion to the surface of the skin, is equally
essential to the well-being of both these
forms, it is very interesting to observe how
admirably this peculiarity in the general re-
quirements is provided for by the very different,
and even opposite, construction of their form
and limbs, which their individual habits of life
demand.

But to return to the detailed anatomy of the
skeleton. On examining the general texture
of the bones in this class, there is an obvious
advance towards the firm calcareous substance
of those of the higher forms of vertebrated
animals when compared with the bones of
fishes, they being more compact, and less tran-
sparent and flexible than in the latter animals.
The cranial bones, though they retain to a
certain extent the character of those of fishes,
in the permanent disunion of the different
centres of ossification, at least in many in-
stances, yet they do not overlap each other,
as in that class, but, on the contrary, remain
with their margins at least in contact, and in
many cases actually united, though not by
true sutures. The elements of which the
cranium is essentially composed, and which
in a higher grade of organization are found
consolidated, are here still exhibited as distinct
pieces; a state of things which is strikingly
imitated in the progress of the development
of these parts in the highest classes during
their growth. It is also to be observed that the
bones of the face are more closely united to
those of the cranium and to each other in
the higher than in the lower forms of the class,
exhibiting distinct and obvious links in the
development of these parts, which we see so
beautifully and gradually perfected in the as-
cending series from fishes up to man. .

The following enumeration of the separate
cranial bones of the amphibia, as existing in
the menopoma alleganiensis, the gigantic sala-
mander of America, will illustrate the general
relations of the distinct centres of ossification,
here remaining permanently detached.

AMPHIBIA.

In figs. 14 and 15 the different elements
are thus designated:—a. the frontal; 0b. the
exterior frontal; c. the parietal; d. the nasal;

e. the occipital; f. the pterygoid; g. the
tympanic; fh. the jugal; 7. the superior
maxillary; k. the intermaxillary; /. the vomer;
m. the sphenoid ; n. corresponding to the or-
bitary processes or ale of the sphenoid. In
the frog and most others the palatine bones
are distinct. We here find that the separate
portions or elements which in this class are
permanently detached, correspond almost ex-
actly with the number found in the cranium
of fishes.

It will be observed by a reference to the
figures, that the intermaxillary bones—and this
is more or less the case in all the amphibia—
are much developed transversely, as in the
fishes, an affinity which has been already so
much insisted on, and which is borne out by
the condition of all the other parts of the cra- —
nium. The lateral extension of the upper and
lower maxillary bones, for instance, as well as _
of the tympanic and jugal, expands the general
form of the skull, without involving any ex-—
pansion of the cavity of the cranium, which is —
restricted to a small, central, elongated space. —
The latter bones also terminate ina condyle, —
which is received into a shallow glenoid cavity —
of the lower jaw, a peculiarity which offers a

| AMPHIBIA.

: still further illustration of the proximity of this
i class to the fishes. The lower jaw consists of
three distinct pieces on each side, an anterior,
a lateral, and a posterior or articular portion.
The anterior bone supports the teeth in those
genera which have teeth in the lower jaw, and
unites with its fellow at the symphysis. In
frogs the lower jaw is devoid of teeth, but they
are found in the upper jaw, bordering the in-
termaxillary and the maxillary bones; and the
vomers are also furnished, each with a trans-
verse row of teeth; but in the salamander, the
menopoma, the proteus, and others, they are
found occupying the margin of the lower jaw.
In the toads there are no teeth in the lower jaw,
but the edge of the jaw-bone is serrated. The
_ second bone of the inferior maxilla occupies
the side, and is larger even than the former. It
has at the posterior part a coronoid process,
behind and within which is placed the third
bone, which forms the medium of articulation
with the cranium.
Itis to the os hyotdes that the principal interest
attaches in the present class, as it is that bone
which undergoes the most remarkable changes
in its form and relations during their transforma-
tion, ane from the office of supporting the
branchial organs into a true os hyoides, and
thus offering, as Cuvier has beautifully shewn,
an elucidation of the true nature of this ap-
paratus in fishes. As this bone, however, has
a direct relation with the respiratory functions,
I shall explain these changes while treating on
that part of the subject.
_ The spinal column varies exceedingly in the

different forms of the amphibia. In the highest
form the vertebra are fewer than are found in
any other animals. In the common frog

Fig. 16.

_ there are but nine, and in the pipa only eight.
_ Of the nine vertebre in the frog, the first, the
_ atlas, a, has no transverse processes ; there are
_ two articular surfaces situated anteriorly, by
which it is articulated to the two occipital
condyles. In the seven following vertebra the
anterior articular surfaces of the bodies are
_ concave, and the posterior convex. This con-
ex tubercle, which enters the concavity of the

93

next vertebra, consists of the intervertebral car-
tilage converted into bone. In the tadpole
condition of the animal (and this remains per-
manently the case in the perenni-branchial
forms, as the menobranchus, the proteus, &c.)
this intervertebral substance retains the soft con-
sistence which characterises it in fishes; and,
as in that class, it is contained in the circum-
scribed cavity formed by the cup-like hollows
of the two articular surfaces of contiguous
vertebre. The elongated fish-like form of
those amphibia which retain their branchie
throughout life, requires that this structure
should also be permanent; and we have thus
another beautiful example of that perfect chain
of organisation which is manifested by this
class of animals, from the fish upwards to the
reptilia.

The vertebre of the adult frog have long
transverse processes (fig. 16, b), but are wholly
destitute of ribs—a class of bones which
would be utterly useless in the particular
modes of locomotion to which these animals are
restricted, and the absence of which implies
a peculiarity in the act of respiration, which
will be described hereafter. The spinous pro-
cesses are very short; the articular are oblique,
the posterior of each being placed above the
anterior of the following one.

The last or sacral vertebra has large transverse
processes (fig. 16, c) directed a little back-
wards, to which the ilia (fig. 16, d) are at-
tached; and to the body of this vertebra is
united by two tubercles, a long single bone,
extending backwards to above the anus. This
bone (fig. 16, e) is considered by Cuvier as a
second sacral vertebra; but by Schultze,
Altena, Dr. Grant, and others, it is regarded
as the coccyx. The vertebral canal occupies
the anterior third of a carina or crest, which
runs along the upper surface of this bone,
diminishing gradually in its course until it
wholly disappears.

The spinal column in the other orders of
the class differs in a remarkable degree from
that which has been just described. In the
salamander there are thirteen dorsal, two sacral,
and about twenty-five caudal vertebra, which in
the genus molge or newt are increased to upwards
of thirty. In these the anterior surface of the
body is convex, and the posterior concave, a
contrary arrangement to that which occurs in
frog. The transverse processes are directed
a little backwards, each, excepting the atlas,
supporting a small rib, which is scarcely curved.

e menopoma has a similar arrangement. In
the stren are found forty-three vertebra in the
trunk, and forty-four or more in the tail. They
all retain in a great measure the form of those
of fishes and of the tadpole of the higher orders
of this class, particularly in the existence of the
intervertebral cavity or double cone, formed
by the apposition of two hollowed surfaces of
their bodies, and filled by a semi-cartilaginous
mass or intervertebral substance. Eight only
of the vertebrae, commencing with the second,
bear ribs, which are extremely small, and in
fact merely rudimentary. In the tail the trans-

94

verse processes are only found on a few of the
most anterior vertebre.

The spine of the proteus is not sufficiently
different from that of the siren to require any
particular description.

The construction of the members, both an-
terior and posterior, especially the latter, will
be found to be arranged on very different plans,
according to the habits and requirements of the
different groups, and particularly their mode of
progression. In the apoda, as the cecilia, there
are not even the rudiments of limbs. In the
other orders they exist under very different
degrees of development, according as they are
constructed for leaping and swimming, as in
the frogs, toads, &c., or for creeping, as in the
salamanders; or they are rudimentary, and
without any very apparent use, as in the am-
phiuma. It will be necessary to give a cursory
description of these forms.

Of the anterior extremity in the anoura—
The shoulder of the frog (fig. 16, f. fig. 17.)
consists of the scapula, the clavicle, and the
coraceid bone, which all combine to form the
glenoid cavity for the head of the humerus.
The scapula is composed of two very distinct
portions. The upper, (fig. 17, a,) which is

Fig. 17.

permanently cartilaginous, at least at its mar-
gin, is articulated moveably to the inferior and
more solidly ossified piece, (fig. 17, b,) at the
inferior and posterior part of which is the arti-
cular surface forming its portion of the glenoid
cavity, immediately anterior to which it is at-
tached to the clavicle. (fig. 17, c.) This
bone is slender and straight, and is connected
beneath with its fellow in the median line.
The coracoid bone (fig. 17, d.) is considerably
larger than the clavicle, and is also connected
with its fellow by its broad median margin.
The sternum consists of several pieces, ex-
tending from before the clavicles to some dis-
tance behind the coracoid bones; the latter
terminates in a broad xiphoid cartilage. These
parts differ considerably in their relative pro-
portions in different genera.

The arm is developed in a very inferior de-
gree compared with the hinder extremity. The
humerus (fig. 17, g ) is short and thick, having
a rounded head, received into the glenoid ca-

AMPHIBIA.

vity of the shoulder-joint. The opposite extre-—
mity forms an almost globular surface for its
articulation with the e of the fore-arm,
which is still shorter, and consists of the radius
and ulna united, (fig. 17, h,) having only a
slight groove to show their line of union. ‘The
carpal bones (fs. 16, i) are = in ie
supporting the four metacarpal bones, oft
he The index and middle finger have each
two phalanges, the others three. The index is
particularly large in the male. The thumb is
merely rudimentary.

The posterior extremity is greatly developed
in the frogs, for the purpose before mentioned,
of enabling them to take long leaps, and to
swim with great rapidity and energy. The
pelvis consists of the three essential bones of
this part, the ilium, ischium, and pubis on
each side. The iliac bones, (fig. 16, d,) di-
verging above, are moveably articulated with
the sacrum. They then extend backwards, and
form, together with the small ischiatic and pubic
bones, (fig. 16, l,) the cotyloid cavities for the
reception of the femur. This bone (fig. 16, m)
is nearly twice as long as the humerus, cylin-
drical, and having a slight double curve.
The leg consists, like the fore-arm, of but one
bone, the tibia and fibula being anchylosed
through their whole length. This bone (fig.16,
n) is even a little longer than the femur. It
is succeeded by two bones of considerable
length, (fig. 16, 0,) haying very much the
aspect of a tibia and fibula, but which must
be considered as bones of the tarsus greatly
modified, and are most probably the os calcis
and the ustragalus. Between these elongated
bones and the metatarsal are four small tarsal
bones. The metatarsal bones (fig. 16, p) are
much elongated, as are also the phalanges,
(fig. 16, g,) for the purpose of forming strong
oars or paddles with the intervention of a broad.
web of integument. The inner toe is consi-
derably developed, and the whole structure of
the foot and leg thus combines to furnish a pow=
erful and efficient organ of progression.

The elongated forms of the aquatic sala-
mander, the proteus, the siren, &c., in which
the vertebree are developed to so great an extent, |
present the opposite extreme in the structure of
their limbs. These are small, feeble, and ap-
pear as it were abortions. In the genus triton
and in the salamandra, which possess both an-
terior and posterior extremities, they differ but
little in their general form and development.
The bones of the fore-arm as well as of the leg,
instead of being respectively anchylosed into
a single piece, as in the frogs, are permanently
separate, consisting of a distinct ulna and radius
in the former, and an equally distinct tibia and
fibula in the latter. The toes are four, both
before and behind; they are short, slender,
and of slight construction. fa.

This imperfect development of the extremi-
ties is, however, as we have seen, admirably —
compensated by the extraordinary extent of the
spine both in the body and the tail; and while |
the limbs afford but very imperfect means of
progression on land, the structure of the spine

* 4

AMPHIBIA.

is admirably adapted to the purpose of swim-
ming, which is performed either by a succes-
sion of curves, as in the amphiuma and the
siren, or by the alternate flexure of the tail, as
in the t¢ritons and the menobranchus.

Having given this general sketch of the os-
teology of the amphibia in the adult state, it
will be interesting to examine the structure of
the skeleton in the tadpole. It has already
been observed that in this early condition of its
existence the animal resembles fishes in all
the most remarkable characters of its organi-
zation. We find accordingly that the limbs,
which are at first scarcely perceptible by the
most minute examination, become gradually
developed, passing through a rudimentary
form beneath the integuments, from which
they do not emerge until they have acquired
considerable size and a very defined figure.
The hinder legs are first seen, and are early
employed as a feeble assistance to the more
effective tail, as instruments of progression.
The tail is developed, however, to a great
degree, occupying the same relative size and
situation as it is found to do in fishes. The
coccygeal vertebre are numerous, forming a
long column, not ossified, but retaining its
cartilaginous structure, at least in those forms
in which it is deciduous; but in the salamanders,
the tritons, the proteus, and all others of the
urodela, it becomes ossified instead of being
absorbed. In the frog and other anoura, as
the permanent organs of progression acquire
their full development, the tail is slowly re-
moved by interstitial absorption, not suddenly
falling off as some have supposed, but be-
coming gradually smaller and smaller until
it wholly disappears. The cranium under-
goes no other important change than that of
the gradual ossification and expansion of its
different elements, the centres of ossification
being at first wholly disunited as in fishes,
and afterwards assuming the more consolidated
structure and closer approximation to each
other, by which they approach the reptilia.

II. Muscular system.—The similarity which
has been already shewn to exist in the osseous
system of fishes and of the tadpole and peren-
nibranchiate amphibia, would naturally lead
to the conclusion that a corresponding affinity
would be found in the muscular apparatus.
The muscles which are employed for progres-
sion in those early forms of vertebrated beings,
are found to consist of oblique layers, abutting
upon a median line, and extending along the
whole length of the tail on each side. A similar
general direction obtains in the muscles both of
the trunk and tail in the long-bodied forms of
the permanently tailed amphibia. The direction
of their action therefore is horizontal, and their
‘progression is effected by the alternate action
of the muscles on each side. These oblique
caudal muscles in the tadpole of the tailless
tribe, become absorbed with the vertebre to
which they are attached, as the animal gradually
assumes its permanent form; but its aquatic
habits are still provided for by the extraordinary
magnitude of the flexors and extensors of the
thigh, leg, and foot, which are in perfect ac-

95

cordance with the great length of the bones of
this extremity, which has been described. The
muscles which form this important apparatus
of motion are exactly analogous to those which
are so peculiarly developed in the human le
Thus the large glutei extend the femur, the
rectus and triceps extend the leg, and by their
united and sudden action forcibly throw the
whole limb into a straight position, whilst the
gastrocnemil, which are here as in the human
subject of sufficient size to form a considerable
calf of the leg, enable the foot with the wide
expanse of its toes, connected as they are by a
tense web, to strike with great force and effect
the resisting medium in which they live, assisted
by the flexors of the toes, which are called into
action at the same instant. The same beau-
tiful mechanism is no less adapted for the pe-
culiar nature of their progression on land; by
it they are enabled to take those long and vigo-
rous leaps which particularly characterize some
of the genera of the acaudate family of this
class. It is obvious that the same sets of
muscles must be developed for the performance
of the energetic and sudden movements above-
mentioned as are required to sustain the upright
form of the human subject in its erect position,
those, namely, which extend at once the thigh
upon the pelvis, the leg upon the thigh, and
the heel upon the leg; and hence arises the
remarkable similarity in the conformation of
the leg in these otherwise remote forms, and
hence too the act of swimming in man must
be a tolerably accurate imitation of the same
effort as exhibited by the frog.

III. Organs of digestion —The foregoing
consideration of the various structures of the
organs appertaining to locomotion would pre-
pare us for corresponding differences in those
belonging to this important office. These
variations, however, are not found exactly to
follow those which have been described in the
former class of organs. The tadpole condition
of the higher amphibia does not correspond
in the nature of its food, nor consequently in
the structure of the alimentary canal, with
the class of fishes, nor indeed with that per-
manent tadpole, as it may be called, the
larviform axoloth.

The teeth, as has been already stated, vary in
the different genera not so much in their size and
form as in their situation. Thus the whole of the
amphibia have teeth in the palate; the sala-
manders have them also in both the upper
and lower jaws, the frogs in the upper only,
and the toads in neither. In the two latter
genera the palatine teeth are placed in a trans-
verse line, interrupted in the middle. In the
salamanders they form two parallel lines, con-
taining not less than thirty on each. In the
menopoma they occupy the anterior palatine
margin of the vomer, forming a line on each
side parallel with the maxillary and_inter-
maxillary teeth. In the avxoloth they are
arranged in the quincuncial order, and are nu-
merous. But the most remarkable form and
arrangement of the palatine teeth is found in
the siren, in which they have the quincuncial
arrangement; they are placed on two small

96

bony plates on each side, probably rudiments
of the vomer and palatine bones. Each of
the larger has six or seven lines of teeth, about
twelve on each line; and each smaller bone
bears four ranges of five or six teeth ; making
in all nearly two hundred teeth in the palate.
Those of the lower jaw in this animal are
placed in similar order. In the proteus the
teeth nearly resemble those of the salamander.

The maxillary teeth are always slender,
sharp-pointed, and closely set. The frog has
about forty on each side of the upper jaw, of
which eight belong to the intermaxillary bone.
The salamander has about sixtyabove and below.

In the tadpole state of the frog the mouth
is very small, and, instead of teeth, is occu-
pied only by minute horny plates of just
sufficient consistence to abrade the soft mixed
food which it finds on the surface of animal
or vegetable substances in the water. Its sto-
mach and intestinal canal are of very different
form from that which they afterwards assume.
The intestine is of nearly equal size throughout
its whole length. It is very long, being not
less than ten times the length of the actual
space from the mouth to the anus, and is coiled
up in a circular form, occupying the greater

art of the abdominal cavity. The canal, as
we shall presently see, changes its character
materially during the metamorphosis of the
animal, becoming gradually shorter until it is
not a quarter of the length, in proportion to
the size of the animal, which it exhibited in
its earlier condition.

In the adult amphibia the whole alimentary
canal is of a very simple character. The
cesophagus is wide and comparatively short.
The stomach single, consisting of a simple sac,
elongated in the lengthened forms of the sala-
mander, the proteus,and other aquatic species.
The intestine is but slightly convoluted, even
in the short tailless family; and there is com-
paratively little difference in the diameter of
its two distinct portions. It terminates, as in
the reptilia, in a cloaca, or pouch, which also
receives the openings of the urinary and genital
organs. ‘The anus in the toads and frogs opens
on the hinder part of the back ; in the other
forms it is situated beneath at the commence-
ment of the tail, as in the reptilia.

The liver, the pancreas, and the spleen are
found in the whole of the amphibia; and
these organs are observed, in the elongated
aquatic forms, to assume a corresponding
lengthened shape. ‘The liver is of considerable
size, particularly in the salamanders. The
gall-bladder exists in all cases, varying, how-
ever, in size and form in the different genera.

IV. Lymphatic and lacteal system.—This
system is highly interesting in the amphibia,
on account of its extreme development, and
of its presenting several important and remark-
able peculiarities in its structure.

The investigations of Professor Muller of
Berlin have lately brought to light the existence
of pulsating cavities in the course of the lympha-
tics, constituting a sort of ventricles for the pro-
pulsion of their fluids towards the veins into
which they are received. In the frog two pairs of

AMPHIBIA.

these little pulsating sacs are found ; at the pos-
terior part one is situated on each side of the
extremity of the coccygeal bone, behind the hip-
joint, and the anterior ones under the posterior
edge of the scapula by the transverse process
of the third vertebra. These cavities are of
considerable size, and pulsate with some degree
of regularity: the pulsations, however, do not
coincide with those of the heart, nor are those
on the one side always synchronous with
those on the other. The posterior ones convey
the lymph received from the legs and hinder
parts of the body into the ischiatie veins, and
the anterior pair, into which the absorbents
of the arms and the anterior parts of the
viscera, &c. open, convey this fluid into the
jugular veins. The internal structure of these
sacs is cellular; they communicate freely
with each other on each side by anastomosing
vessels. On inflating the organ, not only the
lymphatic vessels are inflated, but the whole
of the veins also. Dr. Marshall Hall had
previously observed a somewhat similar pul-
sating cavity in the eel.

These lymphatic ventricles in the amphibia
have still more recently received further exami-
nation and illustration by Professor Panizza
of Pavia, who published the result of his
researches in the year 1833.* Professor Muller’s
discovery was published in the previous year
in the Berlin Annals.

The lymphatic system is developed to an
extraordinary degree in the frogs, as well as
in several other genera of this class, its vessels
being found in numbers and of considerable
size immediately under the skin.

The lacteals ramify upon the surface of the
intestine in two layers, anastomosing and
forming intricate plexuses on the mesentery,
and terminating in two trunks, or thoracic
ducts, which pass forwards one on each side
of the spinal column.

V. Of the sanguiferous system.—lf the
changes, so frequently alluded to, which the
animals of this class undergo in passing from
the condition of a fish to that of a reptile, have
received repeated illustrations in the considera-
tion of the structure of the skeleton, of the
organs of motion, and of those of digestion, far
more interesting and important are those which
occur in the character of the circulation ; in
which the view which has been taken of the
true situation of the amphibia in the chain of
animal development receives the most satis-
factory proof. Beginning life with all the
essential characters of the fishes, even in the
functions of circulation and respiration,
sessing the single branchial heart of that oleae
how wonderful and beautiful are the changes
which these systems of organs undergo, as the
branchiz become obliterated to give place to
pulmonic cavities, and the heart at the same
time assumes the compound character and form
of a systemic and pulmonic heart, in accordance
with the change in the respiratory organs.

The newts, or water-salamanders, afford the —
most satisfactory opportunity of observing these

* Sopra il sistema linfatico dei rettili, fol. Pav.

AMPHIBIA.

changes, as the branchie are large in propor-

tion, and remain external during the whole
period of their existence; the animal also
acquires considerable size before these organs
of aquatic respiration are lost. The heart in
the early stage of these animals consists of a
systemic auricle, which receives the whole of
the blood from the system after circulation, and
of a ventricle which propels it through a third
cavity, the bulbus arteriosus, to the branchial
arteries, of which there is one given to each
branchial leaf. From the capillary branches
of these arteries the aérated blood is received
by the branchial veins, which, as in fishes,
concur to form an aorta without an intervening
ventricle. From the last, or posterior branchial
artery, on each side is given off a branch
which goes to the rudimentary pulmonic sac,
and which ultimately forms the trunk of the
pulmonary artery. But the most interesting
and important change is that by which the
continueus branches of what were originally
the branchial arteries combine to form the two
trunks of the aorta. This is effected by means
of small communicating branches between the
branchial arteries and the branchial veins,
which, as the brahchiz become absorbed, and
their minute branches are obliterated and lost,
gradually enlarge until they become continuous
trunks; and the artery, which was originally
branchial, then becomes the single root of the
two descending aorte, and at its base gives off
the pulmonary artery.

The two veins which return the blood from
the rudimentary air-sacs gradually enlarge as
these cavities become more important, and

assume the character of lungs; and at length

y.

they receive the name, as they perform the
function, of pulmonary veins. These by de-
grees become, as it were, distended at their
point of union with the heart, and ultimately
form the second auricle.

This general description will be better un-
derstood by a reference to the subjoined
figures taken from the tabular views of M.
St. Ange, of which an English edition has

_ been published by Mr. Jones.*

The following detailed description of those
figures is necessary to the correct understanding
this intricate but interesting arrangement.

Reta: Fig, 18.

am
. ey

* Tabular view of the circulation in vertebrated

animals,

‘ VOL. I,

WT

The first period, previous to any change having
taken place in the branchiz, is given in fig. 18.
Four pairs of trunks (1, 2, 3, 4) go off from
the heart. The first branch on each side (1)
gives off a small anastomotic branch (5);
after which it becomes divided into numerous
branchial filaments (6); these, by their ulti-
mate subdivision, terminate in a capillary tissue
or network (7), from which arise other minute
returning vessels, forming, by their junction, a
single large vessel (9), which brings back
blood into the general circulation after it has
been aérated in its course through the branchie.
The second branch (2) also gives off a small
one (14) previously to its subdivision in the
second branchial leaflet, which branch enters
the returning vessel; thus producing a com-
munication between the two vessels 2 and 9,
as in the former case. The returning vessel
then terminates in the arch of the aorta, in
which the two vessels 13 and 15 also terminate.
The third principal vessel (3) is similarly
distributed on the third branchial leaflet, and
the corresponding returning vessel (16) termi-
nates in the aorta, as in the other case. The

arch of the aorta, thus formed, gives off a
branch (21), which, after receiving the fourth
branch from the heart (4), goes into the lungs

(19).

The second period, shewn in fig. 19, occurs
Fig. 19.

The
anastomotic branch (5), shewn in the former
figure, is not much enlarged, and assumes the

when the branchie begin to contract.

character of a continuous trunk with 1. The
branches (11 and 12) have increased in size, but
the original continuation of 1 going to the bran-
chiz, has decreased in the same proportion. The
anastomotic branch (14) has acquired the size
of the arch of the aorta, whilst the continuation
of 2 is diminished, and the branchial leaflet
is contracted in a corresponding degree. The
branch 3 has become exceedingly small; and 4,
which was before the smallest, is now the largest
of all. By these changes in the relative di-
mensions of the different vessels, especially
in the enlargement of the anastomotic branches,
the whole system of the circulation is gradu-
ally being altered, until, in the third period,
(fig. 20,) it has assumed the character of that
in the reptile, by the total obliteration of the
-branchie and their vessels, and the enlarge-
ment of those branches, which, at first only
anastomotic, have now become principal.

In the adult condition of the animal, there-

H

fore, the heart consists of a single ventricle,
and of two auricles. The existence of a se-
cond auricle was first demonstrated in the
higher forms, the frogs and toads, by Dr. Davy,*
and, although in the latest works of Cuvier
and Meckel the auricle in these forms is de-
scribed as single, yet the more complicated
structure has since been amply confirmed by
many other anatomists. _Webert especially
has described the biauricular structure in a
large American frog; but he failed to demon-
strate it in the perennibranchiate amphibia.
From a very interesting paper by Mr. Owen,
in the first volume of the Zoological Society’s
Transactions,{ it appears that the biauricular
structure of the heart was ascribed by Hunter
to all the amphibia except the perennibranchiate
forms; in which, however, the existence of
the left auricle has been satisfactorily deter-
mined by Mr. Owen, who has also given some
very interesting illustrations of the mode in
which the coexistence of branchie and rudi-
mentary lungs is associated with certain pecu-
liarities of the circulation. The circulation in
the adult amphibia, then, assumes exactly the
character which we find in the reptilia, but
in the most simple form.

The little pulmonic auricle receives the
blood perfectly aérated from the lungs by
means of the pulmonary veins. The systemic
auricle at the same time receives the impure
blood from the system by the vene cave. The
blood from the two auricles is sent together
into the single ventricle where it becomes
mixed, and this mingled arterial and venous
blood, thus but half purified, is propelled by
the same impulse, partly into the pulmoné@r
arteries to be more perfectly purified, and the
remainder through the aorta and the whole
circulating system to the different organs of the
body. The aération of the blood, therefore,
is but imperfect; a condition which is met
with equally in the whole of the reptilia.

VI. Respiration—The preceding observa-
tions on the circulation have in some measure
necessarily anticipated the account which we
have to offer of the correlative function of re-
spiration, and the character of those changes

* Zool. Journal, vol. ii.

+ Beitrage von dem Herzen der Batrachicr, 8vo.
1832.

¢ Part iii. p. 213.

AMPHIBIA.

to which its organs are subjected in the transit
of the amphibia from the pisciform to the
reptile state. Breathing water, in the first
instance, exclusively, these animals are fur-
nished in the tadpole condition with branchie
or gills, of a leaf-like form, considerably sub-
divided, though far less so than in the fishes.
These branchiz are, in the first instance, in all
cases external; but in the higher forms of the
class they remain so situated only for a brief
space, becoming, as in the frogs and toads,
internal at a very early period of their ex-
istence. They are supported by cartilaginous
or osseous arches, connected with the os hy-
oides, and the changes which they undergo are
accompanied by alterations in the form of that
bone, to which allusion has already been made,
and an account of which will now be given.
At that period of the tadpole’s existence,
at which its branchie are in full action, and
the lungs still restricted to the state of a black-
ish, rudimentary tissue, we find the tympanic
bones, (figs. 21, 22, €,) developed to a great

Fig. 21. Fig. 22.
d

extent, and forming the basis to which the
branchial apparatus is suspended, by means of
a rather thick angular portion, (figs. 21, 22, a.)
This has been shewn by Cuvier to represent
what in the fishes is composed of three bones,
and is the medium by which in them the
whole branchial apparatus is suspended to the
temporal, and which bears also the branch
ostegous rays. Between these two lateral
branches is a single piece, (figs. 21, 22, 6,)
which, according to’ the same authority, cor-
responds to the chain'of bones placed in most
fishes between the two first branchial arches.
To the posterior point of this bone-are attached
two rhomboidal portions, (c, c,) to the external
margins of which are suspended the arches on
which the branchie ate supported, and which
represent the chain of bones in fishes, bearing
the two last branchial arches.

As the age of the tadpole increases, and its
metamorphosis is proceeding unseen, (, ‘figs.
23, 24,) we find the branches which support

Fig. 24.

the branchial apparatus (a) gradually Jengthen-
ing, i > and © :

AMPHIBIA.

attached to the cranium ; (fig. 25, a,) the single
piece (b,) and the two rhomboidal pieces (¢, ¢,)
1n the meantime become united and extended,
(figs. 25, 26,) and gradually lose by absorption

Fig. 26.

the branchial arches, and ultimately form a
broad disc, the body of the os hyoides, the
anterior margin of which on each side is di-
lated into a scutiform process, and the posterior
margin bears two bony appendages, which are,
in fact, the posterior cornua of that bone.

Such are the changes which this bone un-
dergoes during the gradual passage of the
amphibious animal from the tadpole state, in
which it represents the class of fishes, to its
perfect or reptile condition; and it affords a
most interesting imstance of the manner in
which the true nature of an organ, existing
under ambiguous circumstances in one class of
animals, is often clearly illustrated by its cha-
racters, or, as in the present instance, by its
transformations, in another.

The minute filiform branchie, which are
appended to the tadpole of the frog im-
mediately behind the head, have essentially
the same structure as’ is observed in the gills
of the perennibranchiate family, as the siren
and the proteus, though in a different form.
In the proteus each branchia consists of three
principal divisions or branches, from each of
which proceed seven or eight leaves, again sub-
divided into numerous regular leaflets form-
ing the ultimate divisions of the branchiz, on
which the extreme capillary branches of the
vessels ramify, and in which the blood under-
goes its necessary change. A minute rami-

fication of the branchial artery, conveying the
impure blood from the heart, enters each leaf-
let at its base, (fig. 27, a.) and passes, along

_ Fig. 27.

99

its shorter or inner margin, giving off capillary
branches in its course, which, after meandering
over the surface of the leaflet, and commu-
nicating with each other in various directions,
pass over to the opposite margin of the leaflet,
and reunite in a corresponding ramification of
the branchial vein (6), which passes out at
the base to combine with the corresponding
branches from the other leaflets, and convey
the aérated blood back to the heart. This is
the general structure, modified however in the
different genera, by which this important func-
tion is effected in all the amphibia, as long as
they are confined to their aquatic life; and
whilst the higher groups lose these organs as
they advance, and acquire the necessary organs
for atmospheric respiration, those of the lower
forms retain them throughout life, coexistent
with rudimentary lungs; and thus probably
exhibit the remarkable phenomenon of a two-
fold mode of respiration at one and the same
time in the same individual.

Such, then, is the general structure of the
organs of aquatic respiration, whether in the
early and transitory form in which it is seen in
the frog and the salamander, or in the perma-
nent character which belongs to it in the peren-
nibranchiate group of the siren, the axolotl, the
menobranchus, and the proteus. But as the
former of these groups acquires gradually a per-
fect and unmixed atmospheric respiration, and
as the pulmonary cavity serving this office is
only slowly developed, so we find in the pe-
rennibranchiate forms that the lungs also exist,
though in little more than a rudimentary state.
The. early condition of the lungs in the cadu-
cibranchiate genera, in which they ultimately
exhibit a somewhat advanced structure, is that
of a mere rudimentary sac, without internal
cells or any appearance of even the commence-
ment of that more perfect structure which they
afterwards acquire. Gradually, however, the
inner surface is furnished with small processes,
forming little sacs or cells, on which the capil-
lary branches of the pulmonary vessels ramify,
and through the infinitely attenuated surfaces
of which the impure blood undergoes its essen-
tial process of depuration.

In the lower forms of the class, as in the pro-
teus anguinus for instance, the air-bags, for they
scarcely deserve the name-of lungs in this state,
never arrive at this advanced stage of develop-
ment, but remain permanently in the condition
of simple membranous sacs. Every part of
the apparatus belonging to that organ is equally
rudimentary. The glottis consists of nothing
more than a small slit in the lower part of the
fauces, placed between the branchial apertures
ofeachside. The margin of this little opening,
which has no cartilaginous ring to support it, is
furnished: with a small soft pair of muscles, by

. which it is opened. The tube leading from this

opening speedily bifureates, and one passes to
each air-bag. In this rudiment of a trachea
and of bronchi, there is no appearance of car-
tilaginous rings; it is a mere membranous
canal, each braneh of which opens without any
other apparatus into its air-cell. From the
perfect condition of the branchie, ~ the very
i

100

simple structure of these pulmonary sacs, it will
readily be seen that the function of respiration
could be only very ineffectively aided by the
latter organs, even were there no other diffi-
culty arising from the imperfect structure of the
apparatus which in the air-breathing amphibia
serves the office of conveying the air into the
lungs. A short description of the means by
which the act of inspiration is effected in the
frog will enable us to judge how far it may be
possible that the rudimentary lungs in the pro-
zeus and siren are to be considered as performing
any such function.

In the adult frog, toad, salamander, and all
others of the higher orders of amphibia, the
reception of air into the lungs is effected not
by the primary expansion of the pulmonic cavity
and the consequent rush of air into it, but by
the act of forcing air into the lungs, or in fact
by a simple act of swallowing. This is effected
in the following manner. The os hyoides and
tongue are brought downwards to a considerable
extent, and the cavity of the mouth being thus
much enlarged, the air enters by the nostrils.
The pharynx is then shut at the posterior part,
so as to prevent the passage of air into the ceso-
phagus, and the cavity being suddenly con-
tracted by means of the muscles acting on the
os hyoides, the air is necessarily forced through
the glottis and trachea into the lungs, as the
posterior nares are closed either by their mar-
gins acting as a valve, or by the pressure of the
tongue against them. This view of the mode
of inspiration explains the cause of the well-
known fact, that if the mouth of frogs be held
open they perish from actual suffocation ; for
the motions of the os hyoides being thus im-
peded, and an external passage being also
afforded for the air, respiration by the injection
of air into the lungs is obviously impossible.
Any other mode of inspiration, connected with
the primary expansion of the thoraco-abdo-
minal cavity is obviously impossible in the frog
and its congeners, from the total absence of ribs,
It may not be out of place to explain here the
mode in which the peculiar noise uttered by the
male frog, called croaking, is produced.* Ac-
cording to the observations of P. Camper, the
inspired air is forced against the inferior surface
of the tongue, the protuberance of which di-
vides it as it were into two.currents, which pass
into the membranous sacs adhering to the
lower jaw and existing exclusively in the males.
From these sacs it is directed over the tongue,
and by its vibration the peculiar sound in ques-
tion is produced.

It is an interesting question whether in the
perennibranchiate amphibia, the organs which
have just been described as rudimentary lungs,
do ever serve the purposes of respiration in
even the smallest degree; and it is one of no
small difficulty. The superficial structure of
the nares in the siren and the proteus, in which
they almost exactly resemble those of fishes,
and which would preclude the mode of inspi-
ration practised by the frogs, together with the
slight and attenuated character of the mem-

* Comment, Soc. Reg. Scient, Gotting. v. ix,

‘ AMPHIBIA.

branous tube and sacs, would almost lead to
the conclusion, assumed by Rusconi, that in the
proteus at least these organs do not exercise
any function appertaining to respiration. If
these animals be confined for a considerable
time in the same water, the branchie become
purple instead of having the florid red colour
which characterizes them in a healthy state,
and they die asphyxiated. On the other hand,

the very excitement of the two sacs, accom--

panied by tubes of such length, and opening to
the pharynx by a sort of simple glottis, go-
verned by a distinct muscular apparatus, would
seem to warrant the opinion that a nearer affi-
nity to true lungs is to be traced in these
organs than in the air-bag of fishes, though
recent observations have shewn the latter organ
to be analogous to the lowest rudimentary state
of lungs in the higher animals. The chain of
affinities, therefore, is here perfect, as far as re-
gards the pulmonary cavities.

VII. The nervous system.—The centre of
the nervous system offers a not less striking in-
stance of the progressive development of the am-
phibia in their passage from the pisciform to the
reptile state than those which we have already
shewn in the organs of the other functions of the
body. The condition of the brain in the early
state of the frog tadpole, the genus in which the
changes are most strongly marked, is almost ex-
actly that which it possesses in the fishes. The
linear arrangement of the different lobes, the
broad and lobed form of the medulla oblongata,
the small cerebellum, the large size of the op-
tic thalami, with the distinct ventricles which
they contain, and the very diminutive extent of
the hemispheres, all evince a low degree of
development, and one not yet emerged from
that which we find in the brain of fishes.. The
same imperfect character is also observed in the
spinal marrow, which even in the frog is con-
tinued into numerous coccygeal vertebre, and
as the extremities are not yet in existence, is
devoid of those enlargements which afterwards
take place where the nerves of the anterior and
posterior members are given off. The brain
becomes developed, however, in a very short
period ; the changes which take place being
very rapid, though at last not very considerable;
the hemispheres become enlarged, expanding
laterally and in some measure upwards, con-
stituting the first step towards that superiority
in position, as well as in size, over the other
lobes, which is so conspicuous a character of
these important portions of the brain in the
higher animals. Fig. 28. represents the brain

1, pneumogastric nerve;
2, ninth pair; 3, sixth
pair; 4, acoustic; 5, fa-
cial ; 6, the eye; 7, optic
nerve and its tubercle; 8
and 9, base of the hemi-

tion of ditto; 11, pedicle
of olfactory lobe.

in the common frog after Serres. As the limbs
begin to make their appearance, the enlarge-

spheres ; 10, anterior por-

“<

AMPHIBIA. 101

ments of the spinal cord are observed to take
place, and the contraction of the coccygeal ver-
tebre into a single linear bone, is accompanied
by a corresponding diminution in the length of
that part of the spinal marrow, which at length
only extends, in the form ofa small filament,
into the anterior third of that bone.

The inferior condition of the brain which has
been described as existing in the tadpole of the
higher species, is permanent in the proteus and
other perennibranchiate genera; so that the
brain of the animal just named bears a very
obvious resemblance to that of the larva of the
aquatic salamander or triton.

VIII. The organ of vision.—The eye differs
considerably in its form and magnitude in dif-
ferent genera of the amphibia, and without any
very apparent relation to either their habits or
their circumstances. In the frogs and some
others they are remarkably large and prominent ;
in the salamanders they are comparatively small,
though from their at least equally aquatic
habits, this difference might perhaps have
scarcely been anticipated, and in the cecilia, as
the name imports, the eyes are scarcely if at all
visible. In the latter animal the same object
has doubtless been intended by this absence of
vision, as in the mole and many other ani-
mals, whose common subterranean mode of
life would render the possession of acute
sight not only generally useless, but an extrenie
inconvenience on their occasional appearance
above the surface.

In some points of their structure the eyes of
the amphibia are not remotely related to those
of the fishes ; as, for instance, in the flattened
anterior surface of most of them, arising from
the small supply of the aqueous humour, and
in the depth of the crystalline. In some of
the lower forms, there can scarcely be said to
be a true orbit, the eyes being fixed as it were
in the integuments, and surrounded by a mass
of minute veins, intermixed with extremely
small branches of nerves. Rusconi states that in
the proteus he was not able to discover muscles,
nor even the optic nerve ; though on carefully
and gently raising the hemispheres of the brain
a minute nervous filament was seen going to-
wards the foramen which serves for the passage
of the ophthalmic artery; but whether this
was the optic nerve or not, appears a matter of
entire doubt. In fact, the structure of the eye
in this animal, on the whole, is very imperfect.

In the frog, on the contrary, the eye is fully
developed, and all the essential parts of its
structure sufficiently conspicuous. The globe
of the eye is large and projecting; the scle-
rotic is considerably solid and tough, and semi-
transparent ; the cornea is large, and though
somewhat flattened, is much less so than in
fishes, or in the lower forms of the elass. The
inner surface of the choroid is extremely black,
and the external of a silvery whiteness. The
ciliary processes have not with certainty been
discovered in these animals, unless, as Altena
Suggests, a little tubercular mass, occupyin
nearly their situation, and closely eaunicetud
with the edge of the choroid and with the cap-

sule of the crystalline, may be a modification
of this structure. The iris is covered on its
posterior surface with pigmentum nigrum ; the
anterior having a shining metallic lustre, pre-
cisely similar to that which we see in fishes.
The contractility of the pupil asserted by
Carus is denied by Altena and others. The
retina is thick, and covers the whole internal
surface to the capsule of the crystalline. The
vitreous humour is, in proportion, abundant,
and the lens is large and of a spheroidal shape,
consisting of numerous concentric lamine, en-
closing a nucleus of extreme density, exhibiting
a close relation to the state of this part in
fishes. There are in the frog three palpebre ;
or perhaps, with greater strictness of analogy,
it might be said that there are two palpebre,
and a sort of expansion of the inferior, serving
as a membrana nictitans. The superior pal-
pebra is small, and is not possessed of any
degree of mobility; the inferior is broad, ex-
panded, and semitransparent. It has an in-
ternal membranous expansion, which has just
been alluded to, and which is capable of cover-
ing the whole eyeball.

IX. The organ of hearing.—The function
of hearing exists in very different degrees in
the different groups of amphibia. The aquatic
habits to which the lower forms are confined
by their branchial respiration, would render an
acute perception of sonorous impulses as unne-
cessary as it would be incompatible with the
dense medium in which they live; and we find
in this sense, as in every other function of the
body, the most perfect concord existing be-
tween the habits of the animal and its structural
arrangements. The pisciform aquatic genera
of this class, therefore, are found to possess as
near an affinity to the fishes in the structure of
the organ in question asin most others; and in
this they are also imitated by the tadpole state
of the higher reptiliform groups, the adult
condition of which exhibits a much more ad-
vanced development of the acoustic organ. In
the proteus and the allied genera, there is
neither a tympanic cavity, nor membrana tym-
pani; it consists of a large cavity hollowed as
it were out of the temporal bone, at the bottom
of which cavity is the sacculus with its creta-
ceous body ; the fenestra ovalis is closed by a
bony lamina, the representative of the stapes.
Behind the sacculus are the membranous semi-
circular canals. The whole organ is covered
externally by the integuments, without any pos-
sible communication with the atmosphere.

In the frog, on the other hand, the whole
structure is more complicated. The sacculus,
which is membranaceous, is filled with the
cretaceous matter, which is here semifluid,
having the appearance of cream. The semi-
circular canals are contained within the sub-
stance of the temporal bone. The ossicula
auditus are three, united, and contained within
the tympanum, which they traverse, and are
attached to the membrana tympani, a broad
round membrane, perfectly superficial, and very
distinct from the surrounding integument. The
cavity of the tympanum is not capacious. It

102

eommunicates with the external air by means of
an Eustachian tube passing from it to the
fauces. In all the essential parts of this struc-
ture, there is but little variation from that
which exists in the true reptilia.

X. The organ of smell—The nares in the
perennibranchiate amphibia are, like those of
fishes, confined to little more than a slight
cavity on the anterior part of the head, and
having no continued canal by which they can
communicate with the cavity of the mouth. In
the proteus the similarity of this organ to that
of fishes is so complete, that even the pli-
cated radiations of the lining pituitary mem-
brane are almost exactly imitated. It is of
considerable size, and is contained in a length-
ened canal or cavity, the parietes of which are
in no part osseous. The nostrils terminate im-
mediately under the upper lip. The olfactory
nerves are rather large, and no sooner emerge
from the cavity of the cranium than they divide
into numerous branches of various lengths,
which enter every part of the soft pituitary
membrane.

In the more highly developed genera the
organ of smell has the more advanced structure
which is observed in the reptilia. The nostrils
are partly cartilaginous, partly osseous, and
extend into the cavity of the mouth, though the
posterior openings are placed much more for-
ward than in the higher classes of vertebrata.
The olfactory nerves enter the nostrils through
two openings in the ethmoid bone. The ab-
sence of the convoluted and extensive surfaces
of the turbinated bones, the entire simplicity of
the canal of the nostrils, and the small extent of
its surface, must restrict these animals to a very
circumscribed enjoyment of this function; and
it is probable that the sensibility to odours is
much more acute in the aquatic forms, in which
the organs of sight and of hearing are so im-
perfectly developed, than in the frogs, in which
the organs of these senses are much more
elaborately formed.

XI. Of the organ of taste-—The sense. of
taste, in all the amphibia, as well as in fishes,
is probably very obtuse. The tongue in the
urodela is small, and attached closely at every
part. In the anoura, on the contrary, it is
developed to an extraordinary degree; it is
very long, bifid, and the anterior half is not
only free, but, in its quiescent state, doubled
back upon the posterior fixed part, and capa-
ble of being thrown forwards and again re-
tracted with the rapidity of lightning, serving
as a most efficient means of arresting the
quickest movements of insects, which it con-
veys into the back part of the mouth to be
swallowed.

The application of the tongue as an assistant
in respiration, by closing the posterior nares, in
all higher groups of the class, has been before
alluded to.

XII. The dermal or tegumentary system.—
The absence of all hard scaly adventitious
covering to the skin of the amphibia is one of
the most common, or perhaps it may be said,
the only universal peculiarity by which they

AMPHIBIA.

are, as a class, distinguished from all reptilia.
The amphibious nature of their progressive
development, or the existence at the earliest
period of even rudimentary branchie, can
scarcely be said to be without exceptions, as
several genera have already been mentioned as
not having yet been observed in this condition.
But the naked skin is a character belonging
equally to all, from the serpentiform cecilia to
the typically amphibious frog, and the pisciform
axoloth and proteus. )
The skin of the aquatic genera is soft, smooth,
and furnished with a secreting surface, by
means of which it is kept constantly moist,
and in a state suitable for that cutaneous respira-
tion which strikingly characterises these ani-
mals. Many of those which are generally
inhabitants of the land, as the terrestrial sala-
manders, the toads, and others, are provided
with numerous cutaneous glands, which secrete
a tenacious milky fluid, which is somewhat
acrid, and may perhaps be deleterious if swal-
lowed in any quantity ; though the old opinion
of the poisonous nature of these animals is
altogether without foundation. The fluid which
is poured out from these cutaneous follicles in
the common salamander is copious, of a milky
colour, and consists of mucus, with the addi-
tion of some acrid matter, the nature of
which is not yet known. From the quan-
tity which is suddenly secreted when the ani-
mal is injured or any part of the surface
irritated, it is not improbable that even the
effect of fire may for a few moments be arrested
by it; and thus may have originated the fable
of the salamander having the power of remaining
unconsumed and unhurt when thrown upon
burning coals. The acrid nature of the cuta-
neous secretion of the toad was confirmed by
the observations of Dr. Davy a few years since.
The cuticle of these animals is frequently
shed ; that of the aquatic species comes off in
shreds, and is washed away from the skin. - In
the toads a very curious process takes place for
its removal. When the cuticle has become dry
and unyielding, and a new and softer surface
is required, the deciduous layer splits down
the median line of the back and of the abdo-
men at the same time. The whole cuticle is
thus divided into two parts. By numerous con-
vulsive twitchings and contortions of the body
and legs, this separation becomes more and
more considerable, and the cuticle is gradually
brought off the back and belly in folds towards
the sides. It is then loosened from the hinder
legs by similar movements of those limbs, and
finally removed from them by the animal bring- —
ing first one and then the other forwards under
the arm, and by then withdrawing the hinder —
leg its cuticle is left under the fore leg. The
two portions are now pushed forwards to the
mouth, by the help of which the anterior ex-
tremities are also divested of it. The whole —
mass is now pushed by the hands into the ~
mouth, and swallowed at a single gulp.
The new cuticle is bright, soft, and covered
with a colourless mucus; the old skin was
harsh, dry, dirty, and opaque. is curious —

AMPHIBIA,

process I have repeatedly watched. I have
observed shreds of cuticle hanging about the
terrestrial salamander, which would lead to the
opinion that this animal does not disengage
itself from its deciduous skin in the same
manner as the toad; but as the individuals
under notice were not in health, the observa-
tion is inconclusive.

But the most interesting circumstance con-
nected with the functions of the integuments of
these animals, or indeed with any part of their
economy, is their cutaneous respiration, or the
power which the dermal surface possesses of
effecting those changes in the blood, which are
essential to life, and which are usually per-
formed by particular organs set apart for that
express object, and modified according to the
aquatic or atmospheric medium in which the
depurating agent is applied to them.

Although the experiments of Spallanzani had
long ago demonstrated that carbonic acid was
produced by the contact of the atmosphere
with the skin of frogs, the subject had never
been examined with the care and attention
which its importance demands, until the in-
vestigations of Dr. Edwards of Paris, given in
his work “ On the Influence of Physical Agents
on Life,” set the question at rest, and esta-
blished the proposition by a series of interesting
experiments, so admirably arranged, so satis-
factorily conducted, and so logically reasoned
upon, as to leave no vacuity in the regular
line of induction, nor doubt of the strict correct-
ness of his conclusions.

The existence of a cutaneous respiration in
frogs was proved by the simple experiment of
tying a piece of bladder over the head so tightly
as to produce complete strangulation, and then
placing them under water. On examining the
air contained in the vessel after an hour or two,
a sensible quantity of carbonic acid was de-
tected.

On placing frogs in vessels filled respec-
tively with river water and with water which
had been deprived of its air by boiling, and
inverted over the apertures perforated in the
shelf of a pneumatic trough, containing ninety-
eight and a half pints, those in the latter lived
on the average little more than half as long as
those in the aerated water. On trying the
effect of stagnant water renewed at intervals,
they were found to live two months and a half,
and then died from accidental neglect of renew-
ing the water. Similar results followed ex-
periments made under running water. The
effects of temperature in these experiments
were very striking, and prove that the duration
of life under water is in an inverse proportion
to the elevation of the temperature from 32° to
about 107, at which point the animals die
almost instantly. But oon effects of tempera-
ture were found to be modified by an increase
of respiration, whether by their rising to the
surface and breathing the atmosphere, or by
the quantity of aerated water being increased.

Such is a rapid glance at some of the results
observed by this distinguished physiologist, on
the cutaneous respiration of aérated water ;

103

those which are connected with atmospheric
respiration by the same surface are no less
interesting. In order torender the experiments
as rigorously satisfactory as possible, pulmo-.
nary respiration was prevented by actual stran-
gulation, rather than by keeping the mouth
open, a method which appears liable to some
degree of uncertainty. A ligature was passed
round the neck of six frogs, using the most
rigid compression, so as completely to exclude
any possible passage of air. One of them
lived twenty days ; those placed in five ounces
and a half of water had died in from one to
three days. As the severity of the operation
of strangulation might probably have hastened
death, another mode was tried, namely, the
total excision of the lungs,—an operation which
appeared to produce but little suffering; the
animals were then placed on moist sand. Of
three frogs thus treated, two died on the thirty-
third day, and the remaining one on the
fortieth.

Other experiments were instituted to resolve
the converse of the former proposition, whether
life can be prolonged by pulmonary respiration
alone, unaided by that of the skin? The re-
sult of the experiments made upon tree frogs
and upon the bufo obstetricans, was that pul-
monary respiration is not sufficient to support
life, without being accompanied by the influ-
ence of the skin.

The results of these experiments are not
only highly interesting as regards the habits of
the particular tribe of animals which were the
subject of them, but still more so with refer-
ence to some important questions in general
physiology ; but as their bearing on these,
points can only be shown by viewing them in
relation with all the other subjects treated of in
the admirable work from which they are taken,
it would be out of place to consider them here;
It is impossible, however, not to be struck
with the evidence they afford, that the respi-
ratory organ, that surface through the medium
of which the blood undergoes its necessary
change by the action of oxygen, whether pul-
monary, branchial, or cutaneous, and whether
the medium of its access be water or the at-
mosphere, is in all cases similar, being a
modification of the cutaneous surface. And
as we see in the instance before us, the same
surface capable of performing either atmos-
pheric or aquatic respiration, the inference is
obvious, that pulmonary and branchial organs
may, and probably do, possess an identity of
structure. W hen it is considered too that moisture
is absolutely essential to atmospheric respira-
tion, whether pulmonary or cutaneous, the
identity of the two processes becomes. still
more unequivocal.

This view of the subject receives considerable
confirmation from the fact that branchie are
in many animals capable of exercising the
office of atmospheric respiration through the
medium of a very small quantity of water; as
the land crabs of torrid regions are enabled to
traverse immense districts under a burning
sun, by means of those little reservoirs of

104

water, described by Dr. Milne Edwards,
formed by duplicatures of the lining mem-
brane of the branchial cavity. The eel too, as
is well known, will live for a long time out of
water, from its branchial cavity being capable of
retaining a sufficient quantity of water to bathe
the branchie for a considerable time, thus
preserving those organs in a respirable state.

XIII. Of transpiration and of secretion. —
The particular condition of the skin already
described, naked and consisting of a moist
mucous surface, would render it probable that
cutaneous transpiration should be exceedingly
extensive and rapid in these animals; this is
in fact the case to such an extent, that when
exposed to too great a degree of heat, the eva-
poration of transpired fluid is sufficient to pro-
duce a very rapid decrease in the weight of the
animal; which, if exposed for a sufficiently
long period to its influence, becomes almost
dried up and dies.

One object, and that not an unimportant
one, of the sensible transpiration of fluid in
these animals, the frogs especially, is un-
doubtedly to preserve the skin in a condition
fit for the performance of that cutaneous respi-
ration which has been described. But its still
more obvious purpose is to afford a quantity of
fluid for evaporation from the surface, 1n order to
reduce and equalize the temperature of the body
when exposed. to a degree of heat, sufficient to
incommode or injure it. This will appear
very reasonable when we reflect that these ani-
mals will die in a few minutes, if placed in
water of 107 degrees of Fahr., though respiring
freely with the head above the water, whilst,
on the contrary, they will support for hours the
action of damp air of the same temperature.

The water which is thus transpired is not
the result of the absorption of fluids taken in
by the mouth, for these animals do not appear
to drink. It is received by absorption on the
surface of the skin, to which part it is after-
wards restored when necessary. But in order
to be ready whenever circumstances call for its
use, the fluid thus absorbed is conveyed into a
membranous cavity, formed generally of two
lobes, opening into the cloaca, where it is re-
tained, to be again absorbed, and again con-
veyed to the surface for the purpeses just men-
tioned. When a frog is suddenly alarmed, or
seized, it ejects from its cloaca a quantity of
pure, limpid water, for the purpose of lighten-
ing itself, that it may leap with greater facility.
This fluid is expelled from the sac in question,
and is often mistaken for urine, and the sac for
a urinary bladder. Hence, if a frog be kept in
a moist situation, without having access to
water in any form but in vapour, the skin is
always kept moist, and the water-bag always
filled.

Such is the function attributed in the first
place by Townson to the sac in question, and
after him by Dumeril, Altena, and others ; but
Cuvier, Dr. Grant, and many other anato-
mists consider that it is the true urinary blad-
der. That Townson’s opinion is correct ap-
pears, says Altena, “ from the circumstance that

AMPHIBIA.

the ureters do not terminate in the bladder, but —
in the rectum itself.” Dr. Grant states, that on
the contrary, “the bladder receives the ureters.”

The kidneys are of a lengthened form, in the
‘Na genera, but are shorter in the frogs and
ther anoura.

XIV. On the restoration of lost parts—_
The fact that parts lost by accident, or re-
moved for the purpose of experiment, become
reproduced in many of the lower animals, has’
been known for ages. The actual multipli-
cation of the species in many, perhaps all the’
polygastric animalcula, by spontaneous sepa-
ration,—that of the hydra by artificial division,
—the restoration of lost arms in the different
species of asterias, of the anterior or posterior
extremity of the body in the earthworm, of
the claws of the lobster, and other crustacea,
and of portions of the head in the pulmo-
niferous mollusca, are, all of them, phenomena
which have attracted the attention, and occu-
pied the experiments of physiologists, at va-
rious periods. The experiments of Plateretti,
Spallanzani, Murray, Bonnet, and others, have
shewn that it is not in the invertebrate forms
alone that we are to look for this phenomenon,
but that the amphibia, and even some reptilia,
will reproduce either the limbs or the tail,
when removed. ‘This restoration of the tail
in the saurian reptiles is indeed a common
occurrence, and it often happens that the new
tail is double through the whole of the restored
length.

Of all the observers of this curious phe-
nomenon in the amphibia, Bonnet* stands pre-
eminent for the laborious and patient zeal with
which all his experiments were conducted, no
less than for the conscientious strictness with
which they are recorded. In many experi-
ments he cut off the anterior or posterior limbs
of the common water salamander or triton,
which he found to be invariably restored, and
even the toes were reproduced, and acquired
some degree of motion. The tails were also
amputated at various distances from the base,
and were always renewed. The same limb
was in some cases removed and restored four
times consecutively. In all cases it was ob-
served that warmth encouraged and that cold
retarded the regeneration of the part. The
restored portions were not generally well-
formed, but in some instances varied by excess,
in others by defect. One of the most extra-
ordinary results was that which followed the
extirpation of an eye from one of these ani-
mals. In the course of a year this organ was
completely restored, and its organization was
found to be perfect.

Dumeril records a remarkable experiment
of this nature, in his latest work on the rep-
tila. The subject was the triton mar-
moratus. Three-fourths of the head were cut
off, and the animal was deposited at the bot-
tom of a large vessel having half an inch depth
of water, which was constantly renewed. It
continued to live, and to move slowly. The

a
10)

* (Euvres, in 4to. Neufchatel, 1769.

AMPHIBIA.

nostrils, the tongue, the eyes, and the ears
were gone; the animal could therefore enjoy
no relation to external objects but by the sense
of touch. It nevertheless evinced conscious-
ness, creeping cautiously and slowly about,
occasionally raising the neck to the surface as
if attempting to breathe. ‘The process of cica-
trization at length completely closed the aper-
tures of respiration and of deglutition. It lived
three months after the operation, and then died
from accidental neglect. After all, this expe-
riment proves only the respiratory function of
the skin, a fact already sufficiently established
by the observations of Dr. Edwards before
detailed, and its cruelty does not appear to be
compensated for by its results.

XV. Of reproduction.— The impregnation
of the ova in the amphibia, is effected without
actual coitus; that is to say, it either takes
place out of the body, as in the anoura, or the
impregnating fluid is received by the mere
contact of the external opening of the cloaca
in the two sexes, as in the tailed forms. The
only exception to this statement is in the land
salamander, the male of which has a small
intromittent organ. The act itself of impreg-
nation therefore differs materially in these two
divisions of the class. The generative organs
of both sexes are double, and are placed sym-
metrically in the abdomen. The testes in the
higher forms of the class, the frogs and toads,
are small globular oval bodies, having exter-
nally a bright white appearance, from the
tunica albuginea, and internally a somewhat
loose texture, and a yellowish colour. They
are es behind the liver, attached to the
vertebral column; the vasa deferentia are
humerous, disposed in pairs; they form a
small epididymis, and passing on the outer
side of the kidneys back towards the cloaca,
dilate into vesicule seminales, just before they
terminate in that cavity. These organs, as in
many other animals, become much enlarged at
the breeding season.

The ovaria are situated in the anterior and
upper part of the abdomen, and are internally
divided into numerous sacs, by duplicatures
of the peritoneum, by which also they are
bound to each side of the spine. These sacs
are torn at the period of depositing the eggs,
whether by the pressure of the arms of the
male, as asserted by Prevost and Dumas, or
otherwise, appears uncertain. The oviducts are
small at their commencement, and become
large towards their termination in a sort of
dilated sac, which Altena terms the uterus;
they are of a pulpy substance, having an in-
ternal secreting surface; and the eggs during
their passage through them become enveloped
in a gelatinous mass. They dilate into a sort
of uterine cavity just mentioned, which opens
into the cloaca.

The mode by which the eggs of the frog

from the ovaries into the oviducts appears
yet to be doubtful. The observations of Pre-
vost and Dumas on this subject are generally
received as,correct, but their statements are
denied in some particulars by Altena, and

105.

doubted in others. They state that the ova,
detaching themselves from the ovaries, are
seized by the opening of the tube, but they do
not state the mode by which this act is effected.
It is a question which was long since examined
with great care by Swammerdam, and which
brought him into a controversy; and he con-
fesses at last his ignorance of the mode in which
it actually takes place.

The ovaries enlarge greatly at the breeding
season, and the ova at the time of their depo-
sition fill the body almost to bursting. At the
time of impregnation the male placing himself
on the back of the female, embraces the body with
astonishing force with the anterior legs, which
are pressed under the axille, and the tuber-
cular thumbs, which are at this period con-
siderably enlarged to enable him to retain his
hold, are so essential to this object, that if
they be cut off, he can no longer clasp the
female with the requisite force. The instinct
which instigates the male frog to this act at the
season of breeding is astonishingly powerful,
and sometimes no less remarkably blind.
Thus, it is recorded by Walter, and has been
often observed by others since his time, though
the object of this curious fact has been un-
accountably overlooked, that frogs are occa-
sionally found in the spring adhering with
great force to different parts of the skin of
pike; and a near relative of the writer of this
article has seen an instance of the same kind,
where several frogs were so closely fixed to a
large pike as to require some force to remove
them. This instinct of adhesion is, in fact,
sometimes fatal to its legitimate object. I have
before now taken from the water a large con-
glomeration of male frogs, amounting to per-
haps twelve or more, with one solitary female
in the middle of the mass, dead and putrid,
and even some of the males, towards the in-
terior, pressed into an almost lifeless and shape-
less lump.

While the male is thus closely embracing
the female, an operation which sometimes lasts
for more than a month, the eggs, to the num-
ber of several hundreds, are gradually ejected
from the cloaca, either in masses as in the
frog, or in double chaplets as in the toad, an |
impregnated by the sprinkling of the semen,
as they pass out under the male. In some
species, as the bufo obstetricans, the female is
assisted in the act of expulsion by the hinder
legs of the male. When the eggs are thus
deposited in the water, the jelly-like substance
in which each is enveloped absorbs a large
quantity of it, and the whole mass speedily
enlarges to many times the size of the animal
from which it was expelled.

The male of the bufo obstetricans just men-
tioned, when, by his assistance, the eggs are
excluded, attaches them to his thighs by glu-
tinous threads, and carries them about with
him until the young are ready to leave them,
when he seeks a pool of water in which he
deposits them, and the young shortly afterwards
come forth. ;

The impregnation of the tailed aquatic

106

genera, as the tritons, is effected by a totally
different mode. During the spring, the males
acquire a considerable dorsal membrane, which
runs the whole length of the back and tail,
and is sometimes curiously indented or fringed
at its edge. This membrane is gradually lost
after the breeding season, and its use appears
to be to assist in the act of impregnation.
The male, instead of adhering to the female
like the frog, swims by her side pursuing her
in all her rapid and changing courses through
the water, till at length both remaining for a
moment quite still, he suddenly turns up, by
the assistance doubtless of the dorsal mem-
brane, and places for an instant the edges of
the cloacal aperture in contact with hers, It
is at this instant that the semen is ejected and
received. The eggs are afterwards deposited
slowly, and comparatively few in number,
upon some part of an aquatic plant, on which
the female supports herself by holding by her
hinder legs.

When the embryo has gradually acquired
its larva development, and is ready for its
aquatic life, it bursts the thin membrane which
encloses it, and emerges in the fish-like form
which has been so often alluded to in this paper.

XVI. Metamorphosis—The changes which
take place in the different organs during the
progress of this extraordinary phenomenon,
have been already detailed. It remains to
trace the general form of the animal from the
egg through its larva condition till it receives
its permanent form, and to point out some
remarkable peculiarities observed in different
genera.

In the frog, the toad, and probably all the
anoura, the respiratory organs undergo a double
change, the branchiz being first external for a
very brief period, and afterwards internal during
the remainder of its larva existence. In all
the other forms in which branchie have. been
detected, they remain external till they are lost.

The tadpole, whether of the anoura or of
the urodela, possesses, at first, as we have seen,
the same means of progression as belong to the
class of fishes. That of the triton retains its
branchie, co-existent with four perfect legs,
until it is about a third of its ultimate length.
In the frog the legs which first make their
appearance are the hinder ones; and from the
great development of the tail, and the con-
tinuous form of the head or abdomen, they ap-
pear as if they came through immediately be-
hind the head.

As the terrestrial salamander, though pre-
ferring moist places, does not frequent the
water, the young have not the opportunity of
being developed in that medium; but as the
essential character of their organisation requires
that the first portion of their existence should
be passed in the condition of a tadpole or larva,

we find that the whole of its metamorphosis’

takes place whilst in the oviduct, where it is
found with small branchiz on each side of the
neck, which are lost as the animal enters upon
its terrestrial existence. Like the viper, there-
fore, this animal is ovo-viviparous.

AMPHIBIA.

The arrest of the metamorphosis in the lower
or perennibranchiate forms is confined to the
organs of locomotion in part, to those of cir-
culation, and of respiration. The organs of
reproduction receive their full development,
though even in these there is a considerable
resemblance'to those of the fishes.

One of the most remarkable peculiarities in
the whole of this class, with regard to the sub-
ject now under consideration, is the reproduc-
tion and metamorphosis of the pipa or Surinam
toad. It has long been known that the eggs
are developed in cells on the back of the
mother; but the facts connected with this
curious circumstance have only of late years
been ascertained. It is now established that
the cells on the skin of the female are not
persistent, but grow as the eggs enlarge, and
are removed after the young leave them. ‘The
male impregnates the eggs as the toad, but
immediately places them on the skin of the
mother’s back; here they are attached by a
tenacious mucus, and the skin gradually thickens
in the interstices, forming at length a cell around
each. In these cells the young ones not only
leave the eggs, but actually undergo their
metamorphosis ; and when they leave the back
of the parent, they have lost all the characters of
the tadpole, and have become perfect animals.

It is impossible to contemplate the structure
and habits of this remarkable class of animals
without being struck by the many interesting
points which they offer for the investigation of
the physiologist. Whether we consider the
evident and perfect transition which many of
them present, from the form and structure of
an inferior to that of a superior type or organiza-
tion, the facilities which they afford us of
tracing, as it were under the eye, those mys-
terious changes and grades of development
which in most cases are accessible only at par-
ticular epochs, or are wholly concealed during
their progress in the hidden recesses of the
reproductive organs, or whether we view the
modifications which they present of the respi-
ratory and other important functions of life, it is
not, perhaps, saying too much to aver that there
is scarcely any class of animals which invites the
study and contemplation of the lover of physi-
ological science by phenomena at once so varied
and so interesting as the Amphibia.

BiBLIOGRAPHY.—Boddaert, Abhand, von Am-
hibien, in Berl. Gesels. Naturf. Freunde B. ii. S.
B60, Gray, on the class of animals called by Lin-
neus Amphibia. Phil. Trans. 1789, p. 21. Schnei-
der, Amphib. Physiol. spec. 4to. Frft. a M. 1790-92.
Ditto, Hist. Amphib. nat. et literar, 8vo. Jena,
1799-1801. Laurenti, Synops. Reptil. 8vo. Vien.
1768. Meyer, Synops. Reptil. 8vo. Gotting. 1795.
Latreille, Contin. of Buffon. Hist. Nat. des Am-
phib. Ditto, Hist. Nat. des Salamandres, 8vo.
Paris, 1800. Brongniart, Essai d’une Classif.
Nat. des Reptiles. Société Philom. A. iii. T. 2.
el, Ord. Fam. u. Gattung. der Amphibien. 4to.
unich. 1811. Merrem, Tent. System. Amphib.
8vo. Marb. 1820. Roesel von Rosenhof, Hist.
nat. Ranar. nostrat. fol. Norib, 1746-61. Ed. Alt.
auct. germ. s. t. Naturgesch. der Froesche, &c.
fol. Nurnb. 1800-15. Steinheim, Entwickelung d.
Frosche. 8vo. Hamb. 1820. Hasselt, De metamorph.

ANIMAL KINGDOM.

Ranex temp. Groning, 1820. Kéhler, Obs. Anat.
in Appendices, &c. Ranar. 8vo. Tubing. 1811.
Steffen, De Ranis Obs, Anat. 4to. Berl. 1815.
Mertens, Anat. Batrachiorum prod. 8vo. Halle,
1820. Breyer, Fabric. Rane Pipe. 4to. Berl.
1811. Klétze, De Rana cornuta. 4to. Berl. 1816.
Zenker, Batrachomyologia. 4to. Jenz 1825. Rathke,
De Salamandr. corp. adip. ovariis, &c. 4to. Berl.
1818. Rusconi, Descr. Anat. delle larve delle Sa-
lamandre, &c. 4to. Pavia, 1817. Hj. Amours des
Salamandres fol. Milan. 1821. Hj. Develop, du
Grenouille com. 4to. Mil. 1826. Duges, Sur l’os-
teologie et la myologie des Batraciens. 4to. Paris,
1834, Funk, De Salamandrz terrest. vita, &c. fol.
Berl. 1827. Cuvier, Rech. sur les Reptiles dou-
teux. Par. 1807. 4to. Wagler, Descrip. et icones
Amphib. Monach. 1828. Treviranus, Protei anguin.
Enceph. &e. 4to. Gotting. 1820. Rusconi e Config-
liachi, Del Proteo Anguino, &c. 4to. Pav. 1819,
Barton on the Siren. 8vo. Philad. 1808. Edwards,
Influence des Agens physiques, &c. 8vo, Paris,
1824. Prevost et Dumas in Ann. des Sc. Naturelles,

(T. Bell.)

ANIMAL KINGDOM, an appellation
given to that great division of natural bodies
to which animats belong. Like the other
kingdoms of nature, the mineral and the vege-
table, it is divided into numerous sub-king-
doms, classes, orders, genera, and other subor-
dinate groups, according to the properties and
forms of the objects which it comprehends.
As the primary grand divisions of the mineral
kingdom are founded on the primitive forms of
crystallization, and those of the vegetable king-
dom on the endogenous and exogenous modes
of growth, zoologists have endeavoured to find
some common principle for their first divisions
of the animal kingdom. The most common
function in animals, and in all organized beings,
is generation, and we find the animal kingdom
divided into four distinct groups by the modifi-
cations of this function, viz., fissipara, gemmi-
para, ovipara, and vivipara. But as the fissi-
parous and gemmiparous modes of generation
are effected without the presence of distinct
permanent organs, as the fissiparous mode
occurs in isolated species belonging to classes
remote from each other in the scale, and as
nearly all the classes of the animal kingdom
belong to the oviparous division, the modifica-
tions of this system do not present the means
of establishing primary divisions suitable for
the purposes of zoology. Although the pro-
cess of internal digestion is not so universal
as the function of generation, the internal
alimentary cavity is the most universal organ
of animals, and its forms therefore merit a
first consideration in the establishment of pri-
mary groups. It is found, however, that in
animals whose general structure is nearly the
same, the alimentary apparatus varies so much
according to the nature of the food, as to render
hopeless any attempt to subdivide the animal
kingdom from its modifications; as from its
having one or two apertures, from its being
a simple sac or a lengthened intestine, from
its having one, two, or more stomachs or glands
developed in its course, or other modifications
of this kind.

In the circulating system we are presented
with better means for such divisions than in the
digestive, for the radiated classes have only

107

vessels for their circulation, the articulated
classes have a superadded ventricle, the mollus-
cous classes and fishes a bilocular heart, am-
phibia and reptiles a trilocular heart, and the
birds and mammalia have four cavities in that
organ. ‘The respiratory organs likewise afford
the means of founding primary divisions, as
into ciliated, branchiated, and pulmonated
classes, in ascending from the lowest to the
highest forms of that system.

The primary divisions of the animal kingdom
adopted by Aristotle, viz., animals with red
blood and animals without red blood, are ob-
viously founded on a single principle of classi-
fication, and correspond with the more recent
divisions of vertebrata and invertebrata; but
from the number of distinct classes of animals
now comprehended under each of these divisions,
they are quite unsuitable as primary groups in
the present advanced state of the science of
zoology. Considering the functions of the
nervous system or the intellectual conditions of
animals as a means of classification, Lamarck
proposed three great divisions, the lowest of
which comprehended the animals regarded by
him as apathic or automatic, the second the
sensitive, and the highest the intelligent, which,
however, are too hypothetical to answer the
purposes of the zoologist. Without any fixed
principle for the establishment of his primary
groups, Cuvier divided the animal kingdom
into the radiated, the articulated, the molluscous,
and the vertebrated divisions, which have been
generally adopted by naturalists. From the
importance of the nervous system in the living
economy of animals, some have sought in its
modifications a means of establishing primary
or grand divisions of the animal kingdom on
principles more uniform and philosophical than
those commonly employed. In the radiated or
lowest classes of animals, wherever the nervous
system is perceptible, as in actinia, medusa,
beroe, asterias, echinus, holothuria, &c. it is
found in the form of filaments disposed in a
circular manner around the oral extremity of
the body. This lowest form of the nervous
system is expressed by the term cyclo-neura,
and although, like the radiated and every other
character assigned to these classes, it is of
partial application, it marks the uniform con-
dition of that system on which the manifesta-
tions of life are chiefly dependent, and which
principally establishes the relations of animals
to surrounding nature. A different form of the
nervous system is found in the long cylindrical
trunks of the helminthoid and entomoid classes,
where we observe almost from the lowest ento-
zoa to the highest crustacea, a double nervous
chord or column extending along the whole of
the ventral surface of the body. This form of
the nervous system, common to the articulated
classes of animals, is expressed by the term
diplo-neura, and it is found to accompany an
organization generally more complex than that
of the cyclo-neurose classes, and inferior to that
of most of the succeeding divisions or sub-
kingdoms, especially in the organs of vegetative
or organic life, as the vascular, the digestive,
and the glandular apparatus. The nervous

108

system is more concentrated around the en-
trance to the alimentary canal in the mollus-
cous classes, where it generally forms a trans-
verse series of ganglia, disposed around the
cesophagus, a character which is expressed by
the term cyclo-gangliata. The dorsal position
of the great ganglia and nervous columns of
the cephalopods, and their partial protection by
an organised osseous internal skeleton, leads to
the condition of the nervous system presented
by the vertebrated classes of animals, where its
central parts are in the form of alengthened dorsal
nervous chord developed anteriorly into a brain,
and protected by a vertebral column and cra-
nium. The vertebrated classes are thus de-
signated spini-cerebrata, from the form of the
most influential part of their organization.

To the lowest sub-kingdom or cyclo-neurose
division belong five classes of animals; viz.,

1. Polygastrica, microscopic, simple, transpa-

\

ANIMAL KINGDOM.

rent, soft, aquatic animals, in which no nervous
filament has yet been detected, generally pro-
vided with eyes, with a circular exsertile dental
apparatus around the mouth, and with vibratile
cilia for respiration and progressive motion,
and provided with numerous internal stomachs
or ceca communicating with the alimentary
cavity. (See PoLyeasrrica.) iets
2. Porifera, simple, aquatic, soft, animals,
without perceptible nervous or muscular fila-
ments or organs of sense, with a fibrous internal
skeleton sometimes supported with silicious and
sometimes with calcareous spicula, the body
permeated with a soft gelatinous flesh, covered
externally with minute absorbent pores, tra-
versed by numerous ramified anastomosin
canals, which commence from the pores an
terminate in large open vents, as seen in the
annexed figure of the halina papillaris, Gr.
(fig. 29), which represents the animal as alive,

Ae sh 2%
7 aw © ph® fy
be Ok ae

under water, with the usual currents passing
inwards through its pores (a a), traversing its
internal canals (b), and escaping by the larger
vents (c,d.) (See PoriFERa.)

3. Polypifera, aquatic animals, of a plant-
like form, generally fixed, of a simple internal
structure, for the most part without perceptible
nerves or muscles, or organs of sense, and nou-
rished by superficial polypi, which are developed
from the fleshy substance of the body, as in the
campanularia dichotoma, (fig. 30), where the

Fig. 30.

irritable fleshy tubular portion of the animal is
seen to occupy the interior of the base, the
stem, and the branches, and to extend in the
form of polypi from the open terminal cells.
The polypi of most zoophytes are provided
with tentacula around their orifice, as seen
at B, (fig. 31), and the margins of these ten-
tacula are generally furnished with numerous
minute processes, termed cilia, (see Crx1a,) by
the rapid vibration of which, currents are pro-
duced in the surrounding water for the pur-
Fig. 31. pose of attract-
ing food and
of aerating the
surface and
fluids of the
body, as repre-
sented in fig.
3, A. (See Po-
a An is LYPIFERA.)
4. Acalepha, soft aquatic free animals, of a
simple structure, generally of a gelatinous and
transparent texture, and emitting an acrid se-
cretion which is capable of irritating and
inflaming the skin like the stinging ofa nettle,
from which the name of the class is derived.
They rarely possess a solid skeleton or a
ceptible nervous system. They are all marine,
often luminous, sometimes they possess eyes
with a crystalline humour, they feed on minute
floating animals, and swim by the contractions
of a highly vascular and irritable mantle or by
means of air-sacs, or by the rapid movement of —

ANIMAL KINGDOM.

external vibratile cilia, as in the beroé pileus
represented in fig. 32. This figure represents

Fig. 32.

one of the ciliograde acalephe in which the
mouth (a) is directed downwards, and leads, by
a narrow esophagus, to a wide stomach (6),
and from this the intestine proceeds straight
through the axis of the body to the anus (c) at
the opposite pole. The longitudinal nerves (g),
as in holothuria, proceed from a nervous ring
around the wsophagus. The ovaries (d) extend
along the sides of the intestine ; the surface of
the body is provided with eight longitudinal
bands of pectinated broad vibratile cilia (hh),
and two long ciliated tentacula (ff) extend
from two curved lateral sheaths. (See Aca-
LEPHE.)

5. Echinoderma, simple aquatic animals,
for the most provided with a calcified ex-
terior skeleton or a coriaceous skin, the body
for the most part radiated, globular, or cylin-
drical, often provided with a distinct nervous,
muscular, respiratory, and vascular system.
These animals have received the names of echi-
noderma, from the spines or tubercles which
generally cover their exterior surface, as seen in
the annexed figure of the echinus esculentus
(fig. 33.) The mouth (6) is here in the centre
of the lower surface,
and the intestine (b,b.)
connected to the shell
by a mesentery (c), on
which vessels are ra-
mified, passes in a
convoluted manner
upwards to the oppo-
site axis where the
anal aperture (a) is
surrounded by the five
openings of the ova-
ries (d,d.) The mouth
is surrounded with a
maxillary apparatus
containing five teeth,
and the exterior of the
complicated and solid
shell is seen to be provided with moveable cal-

109

careous spines. These animals are for the most
part free, but some are fixed,as the crinoid
echinoderma, the vascular system is unpro-
vided with auricle or ventricle, and the diges-
tive canal is seldom furnished with distinct
glandular organs. There is sometimes a simple
stomach with one aperture and numerous late-
ral ceca, and sometimes a lengthened intestine
with two terminal openings. Some marine
animals without an echinodermatous covering
are placed in this class from the similarity of
their structure in their more essential organs,
as is the case with the holothuria represented in

jig. 34. The mouth (a) is here surrounded with

ramose tenta-
cula (c) and
an Osseous a
paratus. The
intestine _— ig
long, convolu-
ted, vascular,
supported by
a mesentery,
and _termi-
nates in a
cloaca (7) at
the opposite
axis of the bo-
dy. Therami-
fied internal
branchie (ff)
open from the
cloaca; the
great systemic
artery receives
the aerated
blood from the
branchie, and
the organs of
generation (m)
open near the
anterior part
of the body.
The irritable coriaceous skin is supported by
five broad longitudinal subcutaneous muscular
bands, and five crowded series of tubular mus-
cular. feet extend from its surface. (See Ecur-
NODERMA.)

The SECOND SUB-KINGDOM OF DIPLO-NEU-
ROSE DIviIs1on comprehends four classes of
helminthoid animals and the same number of
entomoid classes, viz.

6. Entozoa, parasitic, simple, internal, or fixed
animals, for the most part of a lengthened
cylindrical form, without distinct organs of
sense or any internal skeleton, the mouth or
anterior part of the body generally provided
with recurved sharp spines, the body generally
covered with an elastic white transparent inte-
gument, the nervous system seldom distinct,
the vascular system without auricle or ven-
tricle, without respiratory organs, and with the
sexes generally separate. (See Enrozoa.) ©

7. Rotifera, minute aquatic animals with
distinct nervous and muscular systems, provided
with eyes, lateral maxille, a dorsal vessel, an
intestine with two apertures, and with vibratile
cilia disposed generally in a circular form

110

around the anterior part of the body. They
are termed rotifera from the appearance of
revolving wheels produced by the rapid move-
ment of the cilia disposed around the mouth.

Fig. 35.

One of these minute wheel-animalcules, the
hydatina senta, is represented highly magnified
in fig. 35, where the mouth (a) is surrounded
with long vibratile cilia (b 6). The esophagus
(c) leads to a capacious stomach (d), which
becomes a narrow intestine below, opening
into the cloaca (e), where the genital organs
(i, 7, g, g, h,) also terminate. Several ganglia
surround the esophagus, and a dorsal vessel
(o 0) is seen extending along the middle of the
back and sending out regular transverse
branches. All the rotifera are free, most are
naked, many are sheathed or loricated, they
exhibit no branchial or pulmonary organs, they
are remarkable for their fertility and their
tenacity of life. (See Rorrrera.)

8. Cirrhopoda, aquatic, articulated, diplo-
neurose animals, with articulated cirrhi, and
branchiz for respiration, body covered with
a fleshy mantle, and fixed in a multivalve
shell. These animals are ali marine, the
branchie are fixed to the hases of the articu-

ANIMAL KINGDOM.

lated cirrhi, the mouth is provided with man-
dibles and maxille, there is a pulsating dorsal
vessel, and a double longitudinal knotted sub-
abdominal nervous chord. The cirrhopoda have
been commonly placed among the molluscous
classes from the form of their exterior coverings.
(See Cirrnopopa.)

9. Annelida, with a long cylindrical body
generally divided into transverse segments, and
covered with a soft skin; the head commonly
provided with antenne and numerous simple
eyes, and the mouth with maxille ; the organs
of motion in the form of simple sete or cirrhi
extending from the sides of the body in a sin-
gle or double row. The vascular system of
the annelida consists of arteries and veins,
without a distinct auricle or ventricle, and the
blood. is generally of a red colour. The re-
Spiratory organs are generally in form of external

ranchiz, sometimes of internal air-sacs, and
the alimentary canal passes straight through
the body with two terminal openings, and with.
numerous lateral cceca developed in its course,
as seen in that of the leech, Atrudo medicinalis,
Fig. 36. (fig. 36.) These lateral coca (b,
c, d, e, f, g, h, i, k, m,) increasing
in length and size from before
backwards, are often much more
lengthened and divided, as in the
halithea. Many of the red-
blooded worms are fixed in cal-
careous, arenaceous, or other
tubes, and many are free and
naked. (See ANNELIDA.)

10. Myriapoda, with a length-
ened articulated body equally
developed throughout ; the head
provided with antenne and sim-
ple eyes; the segments of the
trunk free, without distinction
of thorax and abdomen; the
segments furnished with one
or two pairs of articulated legs
adapted for progressive motion on land; the
respiration is aerial, and performed by trachee,
which ramify from their commencement in
stigmata which open along the whole extent
of the body. They do not undergo me-
tarmorphosis, nor possess compound eyes nor
wings, and they have always more than six
pairs of feet. (See Myrrapopa.)

11. Insecta, with six articulated legs extend-
ing from an articulated trunk, which is divided
into a head, thorax, and abdomen ; the head is
provided with a labium, a labrum, mandibles,
and maxilla, with compound and often also
with simple eyes, and a pair of antenne and
palpi; the thorax supports the six legs, and
commonly one or two pairs of wings, and has
attached to it the moveable segments of the
abdomen, which embrace the principal orga
of digestion, circulation, and generation. The
respiration is effected by trachez, which form
continuous lateral trunks before they ramify
through the body. The circulation is aided by
a pulsating dorsal vessel provided with nu-
merous valves, and the alimentary canal is
furnished with salivary and hepatic, and often
with pancreatic glands. The sexes are sepa-—

a P
;
rh
:
3
th
1a
a
a

ANIMAL KINGDOM. 111

rate, and the genital organs, slow in their
development, are highly complicated in the
perfect state. These animals generally pass
through a series of metamorphoses, and throw
off their exuvial covering five or six times
during their development. This class is the
most numerous in the animal kingdom, com-

rehending about a hundred thousand species.
The greater part of their life is spent in the
larva state, during which they are generally most
voracious, like the young of other classes. - In
the adult state the masticating organs and the
digestive te elm vary much according to
the kind of food in the different species, as is
seen in comparing the alimentary canal of a
carnivorous cicindela campestris (fig. 37.) with

Fig. 37.

that of a phytophagous melolontha vulgaris,

. 38.) In the carnivorous insect (fig. 37.)

intestine passes nearly straight through the
body with few enlargements in its course, and
the glandular organs have a simpler struc-
ture. The msophagus passes down narrow
from the head, and dilates into a wide glandu-
lar crop (a), which is succeeded by a minute
gizzard, and this is followed by the chylific
stomach (b,c), which is covered like the crop
with minute glandular crypte or follicles. At
the pyloric extremity of the chylific stomach, the
liver, in form of simple biliary ducts, pours its
secretion into that cavity by two orifices on each
side(d). The short small intestine (e) opens into
a wide colon (f), which terminates in the anus
(g). In the vegetable-eating insect, (fig. 38)
the alimentary canal is more lengthened, con-
voluted, and capacious, with more numerous
dilatations, and the glandular organs are more
developed. The crop (a) of the melolontha is

Fig. 38.
nr

ay
: i

NY

Y)

W)

%

SEMIN

,
j
mo” |
\

MG

z A ti :
: mK SIE

succeeded by a minute rudimentary gizzard, and
to this succeeds a long and sacculated glandu-
lar or chylific stomach, which becomes narrow
and convoluted below, and terminates in a
small pyloric dilatation, which receives the
four terminations of the biliary organs. The
succeeding part of the imtestine is also con-
voluted, and has three enlargements in its
course to the anus (e). The liver (c c) is
here of great magnitude, and has its secreting
surface much extended by the development of
innumerable minute cceca from its primary
ducts. Insects also often present distinct
urinary organs, and numerous glands in both
sexes connected with the organs of generation.
(See InsxEcta.)

12. Arachnida, with the head and thorax
united, generally four pairs of legs; with-
out antenne, or compound eyes, or wings,
or metamorphosis ; the trunk divided into a
cephalo-thorax and abdomen ; the head is often’
provided with two pairs of chiliform manduca-
tory organs ; the eyes are simple. The respi-
ration is aérial, sometimes performed by tra-
chez, and sometimes by pectinated pulmonary
sacs opening on the sides of the abdominal
surface of the trunk. In their nervous, res-
piratory, and circulating systems they indicate
a higher grade of development than insects,
and like them are generally inhabitants of the
land, attaining considerable size and strength,
with cunning, cruel, carnivorous habits, and
often provided with poisonous instruments.
(See ARacHNIDA.)

13. Crustacea, with the head and thorax
generally united, two pairs of antenne, two

112
compound eyes, more than four pairs of legs,
the respiration effected by gills, and the shell
generally hard and caleareous.. These ento-
moid aquatic animals are generally carnivorous,
and have a short and straight alimentary canal.
Their circulating system is often aided by a
muscular ventricle. The sexes are separate,
and the organs of generation are double and
symmetrical in both sexes. Their biliary or-
gans have a conglomerate form, being com-
posed of minute glandular follicles grouped
together into lobules and larger lobes. Some
of these animals are fixed and parasitic, and
breathe by their general exterior surface; most
are free, and respire by means of branchie
placed under the sides of the carapace or ex-
posed on the under-surface of the post-abdomen.
(See Crustacka.) -

The THIRD, Or CYCLO-GANGLIATED or mol-
luscous DIVISION of the animal kingdom, com-
prehends five classes, viz. :—

14. Tunicata, soft, aquatic, acephalous
animals, breathing by internal branchiz, never
in form of four pectinated lamine, and covered
by a close external elastic tunic furnished with
at least two apertures. The exterior tunic is
lined by a muscular coat; sympathetic ganglia
are observed in the abdominal cavity, and the
respiratory organs are ciliated as in higher
molluscous classes for the production of the
respiratory currents. The mouth, unprovided
with tentacula or other organs of sense, opens at
the bottom of the abdominal cavity,as seen in the
cynthia dione. (Fig. 39.a.) The short cesopha-

Fig. 39.

gus leads to a capacious stomach (6), sometimes
surrounded by the lobes of a small liver, which
pours its secretion into that cavity as in higher
mollusca.. From the stomach a short wide
convoluted intestine proceeds to near the ven-

ANIMAL KINGDOM.

tral orifice (d) of the sac, where it terminates
in the anus (c). The thoracic orifice (e), or the
entrance to the respiratory cavity, is generally
provided with numerous delicate tentacula (_f'),
and a nervous longitudinal filament (A) is ge-
nerally observed to encompass that opening, and
to terminate in a small glanglion (g). These ani-
mals are entirely marine, most are fixed, some
are free ; they are all female, like the conchifera ;
the circulation is aided by a muscular heart.
Many are organically connected in u

othete are isolated, (See Tunicata.) sae

15. Conchifera, acephalous, aquatic auni-
mals, covered with a solid calcareous shell,
consisting of at least two pieces, and breathing
by internal branchiz in form of four pectinated
lamine. These bivalved animals have the
mouth, as in the former class, situated at the
bottom of the respiratory or thoracic cavity ;
the stomach is surrounded and perforated by
the lobes of the liver; the circulation is aided
by a bifid or a divided auricle and by a mus-
cular ventricle, which is generally perforated
by the rectum, as seen in the annexed figure of
the organs of the spondylus, (fig. 40.) The
two fimbriated lips
(a) which surround
the mouth are pro-
longed laterally into |
four tapering flat pec-
tinated tentacular ex-
pansions (b). The
stomach /c) and the
intestine are sur-
rounded by the large
mass of the liver (7),
and the rectum, near
the adductor muscle
(m), penetrates the
ventricle of the heart
(d), at some distance
from the anus (e/,
The branchial veins
(g, h) return the
aerated blood to the
two lateral divisions
of the auricle, these
pour it into the ventri-
cle, by which it is pro-
pelled forwards and

i backwards ° through
the system, so that the heart is here, as in
other invertebrated classes, a systemic organ.
(See ConcuIrera.)

16. Gasteropoda, body invertebrate and in-
articulate, provided with a head which for the
most part supports tentacula and simple eyes,
and furnished with a muscular foot, extended
under the abdomen, and adapted for creeping.
These animals are sometimes naked, more
generally covered with a univalve, unilocular,
solid, external shell. Some gasteropods breathe
by a pulmonary cavity, most by branchie va-
riously disposed on the surface or under an
open mantle. Most are marine, many inhabit
fresh waters, and some reside on land. The
higher forms are mostly carnivorous, and the
lower orders phytophagous, and this difference
affects principally their alimentary apparatus,

ANIMAL KINGDOM.

as seen by comparing that of the carnivorous
buccinum undatum, (fig. 41,) with the same

a tus in the phytophagous patella vulgata,
/y .42.) Like most of the predaceous gas-
teropods the buccinum is provided with a long
muscular proboscis, (fig. 41, a, b,) capable of
being extended to a distance from the mouth,
and enclosing a bifid tongue covered with sharp
recurved teeth. The csophagus near the sto-
‘mach dilates into a small crop (c), and to this
succeeds a round membranous stomach (d, e).
The whole remaining intestine is shorter than the
cesophagus, and dilates into a wide colon (/})
before terminating in the anus (g), on the right
side of the body under the open mantle. The
liver, of great size, and accompanying the
testicle (%) in the turns of the spire, pours
its secretion into the stomach as in the acepha-
lous classes. The vas deferens following the
right side of the body terminates at the end of
the male organ (/) in a small tubular styliform
duct. In the patella, (fig. 42,) however, which
feeds on marine plants, the mouth (a) is provided
with a long slender convoluted tongue covered
with numerous rows of teeth like a long file.
The wide and sacculated esophagus (d) leads
to a capacious and lengthened stomach (f, g),
surrounded by the large liver, and the long
convoluted intestinal canal (h) makes several
turns imbedded in the mass of the liver before
it arrives at the short
dilated rectum (i)
and anus (k). The
salivary glands are
generally of great
size in this class,
and’ present some-
times in the same
species both the
simple _ follicular
and the conglome-
rate forms. The
pancreas likewise is
often present in form
of a single follicle
opening into the sto-
mach along with the
biliary ducts. The
inferior orders are mostly male and female, but
VOL. I.

113

in the higher forms the sexes are distinct. (See
GaSTEROPODA.)

17. Pteropoda, body organized for swim-
ming, mantle closed above, branchiz external,
no muscular foot for creeping, shell, when
present, always thin, pellucid, unilocular, and
moperculate. These soft, minute, floating ani-
mals are all marine, and are enabled to swim
by means of two lateral musculo-cutaneous fin-
like expansions, on the surface of which the
respiratory branchiz or vascular plexuses are
placed. These lateral fins are never supported
by rays. The head is generally provided with
retractile or sheathed tentacula, seldom with
eyes. The body is sometimes entirely naked,
often protected by a delicate thin transparent
shell,which encloses the abdomen and is covered
with a fold of theskin. They appear to be most
closely allied to the inferior testaceous cepha-
lopods in the nature and form of their shells
and in their locomotive powers, and also in
the general simplicity of their internal struc-
ture, especially of their generative organs. The
structure of one of the naked pteropods, clio
borealis, is represented in fig. 43, where the
abdominal cavity is exposed by the mantle

being opened from behind. The mouth (a)
leads to a long esophagus (6), which is sur-
rounded by a circular series of nervous gan-
glia (t). The stomach (cc) is imbedded in the
lobes of the liver (g), which open by numerous
short ducts into its cavity. The esophagus is
accompanied by the two long simple salivary
follicles (k), and at the left or pyloric extremity
(d) of the stomach is placed the heart (2), en-
closed in its pericardium, which receives the
arterialized blood from the branchial veins, and
sends it through the system. The bottom of
the abdomen or cavity of the mantle (h) is
occupied as in the cephalopods with the gene-
rative organs, which consist of an ovary (/)
and long oviduct (m, 0), into which a short
wide cecum (mn), commonly considered as a
testicle, pours its secretion. The oviduct termi-
nates on the left side, near the anus (e), in a
small glandular sac (q), beneath which is the
rhenal sac (p). The pteropods are commonly
found floating in immense numbers at. the sur.
f

114

face of the water in still warm evenings in tro-
pical seas; some, as the clio borealis, figured
above, abound in the Arctic seas. (See Pre-
ROPODA.)

18. Cephalopoda, free cyclo-gangliated or
mulluscous animals, with the feet disposed
around the head, respiring by internal branchie,
and with the abdominal cavity enveloped by a
muscular mantle open anteriorly. The cepha-
lopods are all marine animals capable of swim-
ming by means of membranous or muscular
expansions, which are never supported by rays.
The surface of the body is often naked, some-
times covered witha shell, which is generally po-
lythalamous, rarely monothalamous, and always
inoperculate. There is often a concealed, loose,
dorsal, calcareous or horny shell contained in a
shut subcutaneous sac. The mouth is fur-
nished with two horny or calcified mandibles,
and the rudiments of an internal organized
cartilaginous cranium and vertebral column are
generally perceptible, together with some de-
tached parts of the skeleton of vertebrata. The
cesophagus is surrounded by a nervous collar,
from which two supra-abdominal nervous co-
lumns generally extend along the middle of the
back, and sympathetic ganglia are observed in
the abdominal cavity as in the inferior mollus-
cous classes. These are predaceous animals,
and the alimentary canal, though generally
furnished with three enlargements, forming a
crop, a gizzard, and a spiral or proper chylific
stomach, is always very short. There are two
pairs of salivary glands; the liver is of great
size, and pours its secretion, with that of the
pancreatic follicles, into the stomach, as in the
inferior classes. There is always a strong mus-
cular systemic ventricle, and generally a di-
vided auricle placed at the beginning of the
branchial arteries. The common form of the
chylopoietic organs is seen in those of the
loligopsis guttata, (fig. 44,) where the liver

(a a a@ a)
pours its se-

cretion by
ducts (6),
which are
surrounded

and _pene-
trated = by

the pancrea-
tic follicles
(c c), and
which unite
into a single
canal before
they open by
a valvular
aperture into the third or chylific stomach (fg).
The crop (d) ends in the strong muscular giz-
zard (e), and from the third stomach (,f g) the
short intestine (h) ascends in front of the liver
to terminate by a valvular anus at the base of
the funnel. The naked species have a glandu-
lar sac for secreting a black inky matter, which
_appears to be wanting in those protected by an
external shell, excepting in the argonauta,
where the shell is seen in the ovum, and where
-there is a slight membranous connexion be-

ANIMAL KINGDOM.

tween the animal and its thin delicate calca-
reous covering. The sexes are generally ao
rate, but the lowest foraminiferous cephalo-
pods appear to approach to the pteropods in
the male and female character of the genital
organs. (See CepHaLopopa.)

The last or highest prvisron of the animal
kingdom, comprehending the vertebrated or
red-blooded animals, or SPINI-CEREBRATA, Con-
sists of five distinct classes, characterised chiefly
by their generative, their sanguiferous, and
their tegumentary organs, viz.—

19. Pisces, cold and red-blooded oviparous
vertebrated animals, with one auricle and one
ventricle to the heart, breathing by permanent
branchie, and with fins for progressive motion.
They have a vertebral column and cranium,
enclosing a spinal cord, and brain consisting
of a medulla oblongata, optic lobes, cerebral
hemispheres, olfactory tubercles, and a cere-
bellum. The hands and feet are always formed
like fins for progressive motion in a watery
element. The fins are supported by rays pro-
longed from the skeleton, the body is generally
covered with scales, the trunk is organized
for the lateral motion of the tail, there is
no sacrum, and the pelvic arch is unconnected
with the vertebral column. The bones are
elastic or cartilaginous, and the centres of
ossification for the most part remain perma-
nently detached. The bodies of the vertebre
terminate in two cup-like cavities, they move
on elastic tense intervertebral sacs, and the
transverse processes are directed vertically
downwards in the coccygeal region of the
skeleton to facilitate the lateral motion of the
trunk. The muscles, of a white colour, are
disposed in oblique strata on the sides of the
trunk for the movement of the elastic vertebral
column. The mouth, destitute of salivary
glands, is generally furnished with numerous
unequal, irregular, fangless, osseous teeth, and
the wide cesophagus, short like the neck, leads
to a capacious stomach, from which the in- ;
testine, shorter than in the higher classes, and J
nearly equal throughout, proceeds, without

a ee

ceecal enlargement, to terminate in a cloacal
sac on the inferior surface of the trunk. The
liver is large, and pours its secretion generally
by a single duct into the duodenum, near the
pyloric extremity of the stomach and close
to the opening of the pancreatic duct, as shown
in the annexed figures of these parts in the
frog-fish (fig. 45, A) and the cod (fig. 45, B).
The cesophagus (a) of the frog-fish (fig 45, A)
leads to a large globular stomach (c) with a
strong muscular cardiac sphincter (6). The —
pyloric extremity is also surrounded with —
strong muscular bands (d), and beyond its —
pyloric valve two pancreatic simple glandular —
follicles (ee) open into the duodenum (g) close —
to the opening of the ductus communis chole- —
dochus (f°). In the cod ( fig. 45, B) the wide ~
cesophagus (a) leads to a long and capacious
muscular stomach shut below, and immediately
beyond the pyloric valve, formed by a circular —
fold of the mucous coat, open the ducts of —
numerous straight and simple pancreatic folli-

ANIMAL KINGDOM.

cles (ee) along with the ductus communis
choledochus (f). The cartilaginous plagi-
ostome fishes, the most complicated of this
class, have a conglomerate form of the pan-
creas opening in the same situation. In the
sturgeon and in the sword-fish an interme-
diate form is seen between the simple pan-
creatic follicles of the invertebrated classes
and the more complicated conglomerate organ
in the higher vertebrata. This is shown in
the annexed figure of the chylopoietic viscera
as I found them in the viphias gladius (fig.
46), where the liver (a) is raised up to show

Fig. 46.

the three hepatic ducts uniting with the cystic
from the curved gall-bladder (c) to form a very
short ductus communis choledochus. The
pancreas (d) forms a large reniform mass com-
sed of numerous straight follicles produced

y the successive divisions of the great termi-
nal duct (e) of this organ. This large inter-
mediate organ is surrounded with a distinct
muscular tunic to force its contents into the

duodenum immediately beyond the pyloric.

valve (b). The tortuous small intestine ends

a valvular orifice (f) in a very short but
distinct colon, which presents no cecum in its
course to the anus (g). The bilocular heart

115

of fishes is entirely branchial; it is often pre-
ceded by a sinus venosus, and is always
succeeded by a bulbus arteriosus, which often
presents numerous internal valves in its course.
The venous blood is entirely sent through the
gills, and the branchial veins, after giving
branches to the anterior parts, unite to form
the aorta which sénds the arterialised blood
through the rest of the system without the aid
of a systemic heart. The respiration is effected
by the transmission of water through the mouth
or through distinct spiracula, and over the
surface of the branchiz, which are internal in
the adult, and are often preceded by external
branchie in the young. The lungs are always
rudimentary, when present, sometimes in form
of a shut single air-bag, sometimes divided
or ramified, and most generally communicating
by a ductus pneumaticus with the intestine or
stomach, or esophagus, but seldom employed
for respiration. Fishes are oviparous and have
the sexes separate ; the ovaries are continuous
with the oviducts in osseous fishes, and de-
tached from them in the plagiostome chon-
dropterygii, and impregnation sometimes takes
place internally and sometimes after the ova
are separated from the body. (See Pisces.)
20. Amphibia, cold and red-blooded, verte-
brated, oviparous animals, with three cavities of
the heart, with a naked skin, and breathing, in
the young state, by gills. These animals com-
mence their career like fishes with one auricle
and one ventricle, which send the whole of the
blood through the branchiz, and they have at
this period also double concave bodies of the
vertebra, as in fishes. Many retain the gills
through life, accompanied with pulmonic cavi-
ties, from which the arterialised blood is sent to
a small left auricle. These animals are termed
amphibia from the metamorphosis to a terres-
trial from an aquatic life seen in most of the
species. Their skeleton is imperfectly con-
solidated, their ribs very short or wanting, their
pelvic arch free or nearly so, and their atlantal
and .sacral extremities often very imperfectly
developed or partly deficient. Their toes are
destitute of claws, as their skin is of scales,
and the respiration through their naked, highly
sensitive, and secreting surface compensates for
the imperfect development or limited use of
their lungs, especially during submersion or
hybernation. Some reside constantly in the
water, others occasionally, and others continue
on land. The male organ of intromission is
rarely developed, and impregnation of the ova
is generally effected externally. The genital
organs are double and symmetrically developed
in both sexes. The perennibranchiate amphi-
bia, especially the axolotl, have been shown by
Weber to possess a double auricle like the
caducibranchiate species. (See AMPursia.)
21. Reptilia, cold and red-blooded, ovipa-
rous, vertebrated animals, with two auricles
and one ventricle, not breathing by gills in
their young state, covered with scales, and with
the means of internal impregnation. These
animals, whether aquatic or terrestrial, breathe
only by means of lungs, and their pulmonic

respiration and the left auricle of the heart are
I 2

116

greater than in the amphibia. Their bones are
more consolidated than in the lower vertebrata,
their pelvic arch, when developed, is more firmly
attached to the vertebral column, the centres of
ossification, especially of the cranial bones,
generally remain detached, the extremities are
for the most part more competely developed,
and the toes are generally provided with claws.
Their cerebellum is remarkably small, their
muscular irritability languid, and they have
great tenacity of life. ‘This ventricle, which
receives both the venous and arterialised blood,
is more or less divided by an ascending imperfect
septum. The thoracic and abdominal cavities
are not separated by a muscular diaphragm, and
the lunzs extend backwards over the abdominal
viscera. Their organs of generation are double
in both sexes, and symmetrically developed on
the two sides of the body. The two portions
of the corpus cavernosum are often detached
and bifid; the chorion of the ova is generally
thin or coriaceous, seldom calcified or hard,
and the instincts of the parent generally extend
to the protection of the young. (See Reprixra.)

22. Aves, warin and red-blooded, ovipa-
rous, vertebrated animals, with four cavities of
the heart, covered with feathers, and with their
arms organized for flight. Their bones are the
most compact and dense in texture, the most
extensively anchylosed, and generally contain
air admitted from the cells of the lungs. Their
tympanic bone is moveable, they have horny
mandibles in place of teeth, their coracoid
bones reach the sternum, the sternal ribs are
ossified, and they want the tarsal bones. Their
diaphragm never forms a complete partition
between the thoracic and abdominal cavities.
The hemispheres of the brain are without con-
volutions, the optic lobes are large and hollow,
the cerebellum is large and sulcated, and the
posterior enlargement of the spinal chord of
great size. The great irritability of their mus-
cular system corresponds with the great extent
of their respiration, the high development of
their nervous system, the rapidity of their cir-
culation, and the increased energy of all their
functions. Their alimentary canal is furnished

with a crop, a glandular infundibulum, a giz-
zard, and generally with two ce@ca-coli, as seen
in the annexed diagram (fig. 47), showing the

Fig. 47.

ANIMAL KINGDOM.

common form of these parts in a gallinaceous
bird. In these gallinaceous birds the esopha-
gus (a) sends out at a right angle with its
course a large crop (b), with a contracted
neck, and supplied with glandular follicles.
Beneath this is the infundibulum or glandular
stomach (c), with numerous large follicles
placed between the mucous and muscular
coats, and this opens into the large muscular
gizzard (d), provided externally with two strong
digastric muscles (e). The cardiac and py-
loric orifices of the gizzard are close to each
other (f), and towards the lower part of the
small intestine a minute cecum often indi-
cates the original entrance of the yolk-bag.
The two long ceeca-coli (g) commence by nar-
row entrances (/), and the short colon ends
in a common cloaca (/) for the genital and
urinary secretions.

Inthe predaceous birds, as the eagles (fig.48),
the cesophagus (a), the crop ()), the infundibu-
lum (c), and the gizzard (de), are capacious, thin,

Fig. 48.

and membranous, and form a continuous cavity
for the prey, from which the indigestible parts
can be thrown out in a-bolus. In these birds
the ceca-coli (g) are very small, sometimes
unequal, or wanting. The urinary (2) and
genital organs (kk) enter the cloaca (/) near
the anus. The right ventricle of birds has the
tricuspid valve in form of a thick strong mus-
cular fold, and the aorta descends on the right
side. The lungs form two undivided, light-
coloured lobes, fixed by pleure to the back part
of the trunk, the last rings of the trachea form
an inferior larynx, the bronchi pass in a mem=
branous form through the lungs, and the lunge

;
Lo Se

open into large membranous abdominal air- —
cells, which communieate with the interior of ©
the bones. ‘This extensive aeration of thei
systemic as well as their pulmonic vessels giv
energy to their muscles for their aerial life ;
their distant migrations, and a high temp
ture to their body for the incubation o
egg. Their plumage and their downy cove
are the best suited for their aerial life and th
high internal heat. Their organs of generati
are double and symmetrical in the male,

8

ANIMAL KINGDOM.

generally unsymmetrical in their development
inthe female. The testes are internal, and the
vasa deferentia terminate in the cloaca, where
there is sometimes a grooved organ of intro-

4 mission. In the female the left ovary and
oviduct are developed, the right for the most
4 part atrophiated and useless. The cavity of

the cloaca in most birds, as seen in that of the
great condor of the Andes (fig. 49), receives
___ the end of the rectum (a), which forms a wide

Fig. 49.

rectal vestibule (6): beneath this lies the part
analogous to the urinary bladder (c d). Lower
than the urinary sac are found the two openings

of the ureters (A A), with the pervious oviduct

on the left side (/'), and the remains of the

_ impervious oviduct (g) on the right side. The
_ bursa Fabricii and the clitoris (when present)
_ are placed more posteriorly in the preputial
_ cavity. The most distinct forms of these gene-
rative and urinary parts, and the nearest ap-

_ proach to the mammalia are seen in the cloaca
of the ostrich (fig. 50), where the rectum (a)
3 i into a wide and distinct recta! vestibule
_ (6), which extends into a large urinary bladder
_ (d). Beneath the urinary bladder is the ure-
| thro-sexual canal (e), into which the two ureters

ib Fig. 50.

Ai RAMEE NTA OR

i A a tA lie listo

.¥

(hh h® h*) and the oviducts (f.f* £* g) open
_ towards the dorsal and lateral part. The 6

_-puti cavity (7) is the terminal portion in which
_ the distinct clitoris is here lodged. The ova

6
i

‘
‘
is
4

117

are impregnated internally, their chorion is
calcified, and their development is effected by
incubation, (See Aves.)

23. Mammalia, warm and red-blooded ver-
tebrata, having four cavities of the heart, with
a viviparous mode of generation, and possessing
mammary glands; with the lungs free in a
distinct thoracic cavity, and genera!ly having
the body more or less covered with hair. The
bodies of their vertebre unite by flat surfaces,
the tympanic bone is fixed, the Jaws are gene-
rally furnished with teeth lodged in deep alveoli,
the coracoid bone rarely reaches the sternum,
and the posterior extremities, when present, are
always attached by the pelvic arch to a solid
sacrum. The thoracic and abdominal cavities
are separated by a muscular diaphragm. The
hemispheres of the brain contain large ventri-
cles, and rarely want conyolutions, the optic
lobes are small, concealed, solid, and divided
by a transverse sulcus, the commissures of the
brain and cerebellum, and the hemispheres of
the cerebellum are large. The alimentary
canal is of great length, the colon long and
wide, with a single cecum, and sometimes
with a vermiform appendix, and the anal open-
ing is generally distinct from the urinary and
genital passages. The tricuspid valve is thin
and membranous, the aorta descends on the
left side, there is no inferior larynx, the epi-
glottis is distinct, and the bronchi continue
cartilaginous into their ramifications in the
lungs. Thelungs, generally divided into lobes,
move freeely in a distinct thoracic cavity, and
have no abdominal cells or perforations on their
surface, as in birds. There is always a urinary
bladder, and the urethra in the male passes
through a tubular penis. The organs of gene-
ration are double in both sexes, symmetrical in
the male, and rarely unsymmetrical inthe
female. The oviducts commonly unite at their
lower part to form a uterus, in which the ovum
becomes again connected with the parent, and
is hatched. There are mammary glands open-
ing externally for lactation during the helpless
condition of the young. (See MammMattia.)

These are the primary and SECONDARY
DIVISIONS of the ANIMAL KINGDOM, the struc-
ture,. classification, and history of which it is
proposed to consider in this Cyclopedia, under
the heads of the several classes as enumerated in
the subjoined table.

ANIMALIA.
I. Sub-regnum, Cyclo-neura vel Radiata.
Classis 1. Polygastrica.
2. Porifera.
3. Polypifera.
4. Acalephe.
5. Echinoderma.

Il. Sub-regnum, Diplo-neura vel Articulata.
Classis 6. Entozoa.
7. Rotifera.
8. Cirrhopoda.
9. Annelida.
10. Myriapoda.
11. Insecta.
12. Arachnida.
13. Crustacea.

118

III. Sub-regnum Cyclo-gangliata vel Mollusca.
Classis 14. Tunicata.
15. Conchifera.
16. Gasteropoda.
17. Pteropoda.
18. Cephalopoda.

IV. Sub-regnum Spini-cerebrata vel Vertebrata.
Classis 19. Pisces.
20. Amphibia.
21. Reptilia.
22. Aves.
23. Mammalia.

For the BIBLIOGRAPHY of this article see that
appended to each of the articles on the classes of
animals and COMPARATIVE ANATOMY ( Introduc-

tion.)
(R. E. Grant.)

ANIMAL (from anima, breath, the living
principle. Lat. animal. Gr. Giov. Fr. animal.
Germ. Thier. Ital animale). The objects of
the material universe were long considered as
arranging themselves naturally into three grand
divisions, or kingdoms, as they were called: the
animal, the vegetable, and the mineral. Closer
attention, however, and a more careful study of
the qualities and actions of the various bodies
composing these kingdoms, lead to the con-
clusion that two of them have much in com-
mon, and consequently that a two-fold division
suffices to comprehend the whole of the objects
in nature,—these are the inorganic, or lifeless,
and the organic, or living; the first embracing
minerals, fluids, gases, or the various forms
in which simple brute matter presents itself to
our observation ; the second including vegeta-
bles and animals.

As the subject ANIMAL may be regarded in
the light of the very kernel and epitome of the
entire matter treated in the pages of our
Cyclopedia, we shall give such extension to
this head as its importance seems to demand,
studying brevity nevertheless, and embracing
in general views the particular points which
will be illustrated in detail in the different
articles on anatomy and physiology, human
and comparative.

COMPARISON OF THE ORGANIC AND INORGANIC
WORLDS.

Physical qualities and elementary composi-
tion of unorganized and organized bodies.—
The organic and inorganic kingdoms of nature
are distinguished from one another by many
strong features of difference,—first, in reference
to their general physical qualities, external
form, volume, and elementary composition ;
and second, in regard to their capacities of
action.

The forms of the objects composing the
inorganic world, indeterminate when they are
considered in their masses, are reducible to a
very few simple crystalline shapes when they
are regarded in their parts. The cube, the hexa-
hedron, the rhomb, the prism, &c. are the ele-
mentary forms of the inorganic world: plane
surfaces and straight lines uniting under differ-
ent inclinations, and originating angles that
measure certain determinate numbers of de-

ANIMAL.

grees are the accidents, which give them their
characteristic and individual shapes.

But the inorganic world has not absolutely
even this limited perfection of form, if the ex-
pression may be allowed. In order that the ob-
jects which compose it may exhibit themselves
under the form of crystals, solution of some
kind, rest, time, and space are required; and
these or any of these being denied, the ob-
jects of the unorganized world present them-
selves or exist as simple aggregates of mo-
lecules, shapeless in their component parts as
in their masses. And further, even when the
objects of the inorganic world do present them-
selves under definite forms, these are not ne-
cessary and invariable. Carbonate of lime,
to take a single instance, occurs crystallized
not only in rhombs, but in hexahedral prisms,
in dodecahedrons, the several faces of which
are pentagons, in solids terminated by twelve
triangles with unequal sides, &c. In their
material composition, too, unorganized bodies
are essentially homogeneous: one part of a
mineral does not differ from another.

This is very different from what occurs in
the world of organization. From the lowest
to the highest of living beings the shape is
determinate for the individual, not only as
a whole, but even as each of its component
parts is concerned. Instead of being cir-
cumscribed within angles and right lines like
the objects of the inorganic kingdom, those
of the organic are mostly rounded in their
forms, or they are branched, or articulated and
made up of several parts, which present varieties
of conformation in harmony with the kinds of
offices they have to perform, or the conditions
surrounded by which the beings thus fashioned
exist. Neither do they consist of homogeneous
particles like minerals, but are made up in
general of heterogeneous parts: in plants we
have roots, leaves, branches, flowers, &c.; in
animals muscles, nerves, bones, and a great
number of organs besides, each itself reducible
to a variety of simpler parts or elements, en-
titled tissues.

The organic world also presents an immea-
surably greater variety of forms than the in-
organic: the myriads of animals and vegeta-
bles that people and possess the earth differ to
infinity from each other in their forms and
physiognomies.

Size.—Neither is there less discrepancy be-
tween the inorganic and the organic world in
the quality of size, which, in the first, is
perfectly indeterminate, being greater or less,
simply as the constituent molecules happen
to be aggregated in larger or in smaller num-
bers. The volume of organized bodies, on —
the contrary, is determinate; every animal,
every vegetable, has a particular stature, a cer
tain bulk, which is that of its species also, and —
is within narrow limits alike in regard to all”
the individualg composing the kind. a

Composition —Contrasted in their chemical
nature, organized and unorganized bodies pre-
sent numerous and striking points of dis-
similarity. Modern chemistry enumerates no
fewer than fifty-two elementary or simple sub-

ANIMAL.:

stances,*. besides the imponderables — light,
caloric, and electricity. ‘The whole of these
are met with in the mineral or inorganic world;
but no more than nineteen of them have been
detected in the constitution of organized bo-
dies.t Six of this number, indeed,—oxygen,
hydrogen, carbon, azote, phosphorus, and cal-
cium, occur in such abundance as to compose
almost the whole mass of organized bodies;
the remaining thirteen are met with but spa-
ringly distributed, and some of them even
appear to be adventitious, and by no means
essential to the constitution of the bodies in
which they are encountered.

Speaking generally, the chemical composi-
tion of inorganic objects may be stated to be
the more simple, many of them consisting of
a single element only, and when more com-
pound generally presenting binary, and at
most ternary combinations of known elements.
Organized bodies, on the other hand, are never
made up of single elements, they are not even
binary combinations, vegetables in the aggre-
gate being at least ternary, and animals at
least quaternary compounds. Though’ the
elements which compose inanimate objects,
therefore, are more numerous, the combinations
they enter into are less complex than those they
form in the constitution of living things.

Another difference in the chemical consti-
tution of unorganized and of organized bodies
consists in the mode or form in which the che-
mical elements exist in each. In the former
they present themselves zmmediately as it were,
the chemist in his analyses coming upon them
at once; in the latter they occur under two
forms, the one immediate as in minerals, the
other mediate, or arranged under a variety of
_ hew and peculiar shapes, which, with reference
to the bodies they mainly constitute, are con-
veniently and fairly spoken of as elements,
with the prefix organic, they being exclusively
the products of life and organization; these
are also frequently spoken of as the immediate
principles of vegetables and animals.

In the inorganic world, again, the con-
Stituent elements of bodies are always united
by virtue of, and in harmony with, the general
laws of chemical affinity, whilst in the organic
the compounds formed are very often even
the opposites of those that would have been
originated under the dominion of these laws.
From this it comes that, whilst the chemist
finds almost as little difficulty in recomposing

* Oxygen, hydrogen, carbon, phosphorus, sul-

ur, rium, silenium, iodine, fluor, chlorine,
romine, azote, silicium, zirconium, aluminium,
yttrium, glucynium, magnesium, calcium, stron-
tium, baryum, potassium, sodium, lithium, man-
ganese, zinc, iron, tin, arsenic, molybdenum, tung-
sten, columbium, chromium, antimony, ciranium,
cerium, cobalt, titanium, bismuth, cadmium, cop-
per, tellurium, lead, mercury, nickel, osmium,
silver, gold, platinum, palladium, rhodium, and
iridium.

_ + Oxygen, hydrogen, carbon, azote, phosphorus,
sulphur, iodine, bromine, chlorine, fiuor, silicium,
aluminium, magnesium, potassium, sodium, cal-
cium, manganese, iron, and copper.

119

as in disintegrating inorganic objects, he has
hitherto failed in compounding any one of the
higher organic products or immediate prin-
ciples of plants and animals.* Chemical
analysis we may therefore imagine to be a
process of a very different nature as applied
to inorganic objects from what it is when ap-
plied to organic substances. With reference
to the former it signifies a simple disintegra-
tion, with an inherent capacity in the elements
separated to reunite into the compound ana-
lysed; in the latter it constantly implies de-
struction, without any such continuing power
of recombination among the constituent ele-
ments. Chemical synthesis, consequently, is
an expression that can only be logically used
in connection with inorganic. objects.
Considered with reference to their intimate
texture, organized beings are no less strikingly
different from unorganized bodies. The last
are either solid, or fluid, or gaseous ; they never
occur commingled, each subserving the ex-
istence of the other. The water of crystalli-
zation, and the globules of this and other fluids
occasionally found included within the sub-
stance of minerals, are but adventitious, being
in the first instance entangled among their
component molecules, in the second imprisoned
within accidental cavities in their substances
but contributing in nowise to the existence
or duration of the matter that surrounds them.
Organized bodies, on the other hand, consist
uniformly of solid and of fluid parts: whilst
the vegetable has its woody fibre and constituent
parenchyma, it has its sap also; and animals
with their firmer bones, muscles, cellular sub-
stance, &c. have likewise blood circulating
through their bodies, or various fluids de-
posited within their tissues, which are just as
essential to their constitution and continuance
as the containing parts themselves. It is even
by the mutual play of the solids and fluids
which enter into the composition of organized
beings that they manifest themselves in action
or exhibit the phenomena which are peculiar
to them, and which we denominate vital. It
were indifferent whether we took away the
solids (were such a thing possible) or the
fluids of a vegetable or an animal; in either
case it must perish. The solids and fluids of
organized beings consequently are in intimate
and inseparable relationship one with another.
Consistence.—From this admixture of solids
and fluids in the world of organization results
the variety of consistence which its objects pre-
sent. In the inorganic kingdom, rigidity,—
rigidity, too, which is uniform,—is one of the
distinguishing characteristics. In the organic,
on the contrary, pliancy and softness, which
vary as well in every individual as in almost

* The exceptions to this position are scarcely
worth noticing—one or two of the more simple
organic elements, oxalic acid and urea, for ex-
ample, have been formed s nthetically, and a
substance bearing a remote affinity to fat has also
been produced. No onc, however, has ever suc-
ceeded in forming fibrinc, neurine, fecula, gum,
&c. synthetically.

120 ANIMAL.

every part of the same individual, are no less
strongly marked and inherent features. So-
lidity or hardness may be looked upon as the
term of perfection of a mineral; softness, on
the other hand, often appears to be the term of
perfection among vegetables and animals, the
parts in these being generally softerin proportion
as they have more important or noble offices to
perform. ‘The tender fibrils of the root, the
leaves, flowers, stamina and pistilla in plants ;
the brain, vessels, viscera, &c. in animals, are
softer than the bark and woody fibre, than the
bones, ligaments, skin, &c. which form, as
it were, but the frame and covering of the
proper fabric. This quality also varies in the
organic world according to the age of the in-
dividual: the nearer any organized being is to
its birth or origin, the softer will it generally be
found to be; the longer it has lived, the harder
will it as uniformly be ascertained to have
become. Many organized beings, indeed, in
the first stages of their existence, are wholly
fluid; they only acquire consistence as they
are evolved and approach maturity.

It is almost needless to speak of the ex-
tent to which inorganic bodies differ from or-
ganic in these respects; they are rigid and
hard in all their parts alike, and never vary in
consistence from the moment of their forma-
tion to that of their disintegration or decom-
position.

The elementary particles or molecules en-
tering into the composition of organized and
unorganized objects, also differ in their essen-
tial nature. All organized beings, in fact,
whether their solids or fluids are regarded,
appear to be made up of or to contain glo-
bular or oval and sometimes flattened cor-
puscles. The simplest plants,—the conferve,
tremelle, &c., and the simplest animals,—the
infusoria, polypi, &c., are alike composed of
globules and a fluid; nor is the case different
as regards the most complicated vegetable or
animal that exists. The elementary globule
has now been discovered in almost all the
solids and fluids both of vegetable and of
animal bodies,—in the sap and cambium or
succus proprius of vegetables, and in the
blood, chyle, milk, and other fluids of animals ;
in the fecula, albumen, parenchyma of the
leaves, cells of the flowers, &c. of plants, and
in the cellular membrane, muscle, brain, nerve,
gland, &c. of animals.

Nothing of the same kind has yet been de-
tected among inorganic bodies. Angular par-
ticles separable to infinity into others of a like
description are the elements of composition in
minerals.

Globules, then, are to be regarded as the
elementary constituents of organized bodies,
as the ultimate molecules possessing a distinct
form, which by their aggregation compose them.
The first step, indeed, in the singular pro-
cess by which infusory animals are eliminated
during the decomposition of organized sub-
stances, is the formation of globular corpuscles ;
these, by their subsequent aggregation in some
cases and individual evolution in_ others,

appear to give birth to the organized atoms

that by-and-by make their appearance ; and,
as we have said, globules are now admitted to
form the basis of the different tissues which
enter into the composition of the very highest
among animals. ‘These various tissues, in fact,
would seem to result from the different modes
in which the elementary globules are disposed ;

and it is not improbable that the difference

of function they exhibit may yet be found in’
harmony with, and perhaps depending on, pe-
culiarity of arrangement in their constituent
molecules.

This aggregation of the organic molecules
into a variety of tissues and peculiar organs
forms another essential feature of difference
between the organized and the unorganized
world. Minerals, indeed, as they manifest no
variety of phenomena analogous to those of
life, required no diversity of elementary con-
stitution in their different parts ; they are con-
sequently homogeneous. In minerals the com-
ponent molecules are arranged in layers placed
one upon another, so that their crystals can be
readily cleft in a variety of directions, according
to the elementary arrangement of these. In
vegetables and animals, on the other hand, the
constituent molecules always form tissues, the
fibres of which interlace or cross one another ;
in no living or organic thing do we observe
aught similar to what is called the cleavage in
minerals.

From this it comes that minerals are as com-
plete in their parts as they are in their masses :
the minutest spark of carbonate of lime has all
the properties of a crystal of this substance,
were it as large as a mountain. The case is
very different in regard to organized beings ;
these consist of a number of organs, the sum
of whose actions constitutes the peculiar vitality
of each being, and no individual part or organ
enjoys capacity to manifest itself abstractedly
from the system to which it belongs. All the
parts of organized bodies are mutually en-
chained by bonds of the strictest causality ;
this even follows necessarily from the manner
in which they originate and are evolved. The
radicle that bursts from the fecundated seed
of a plant determines the growth of the stem,
which subsequently and in its turn plays the
same part with reference to the leaves and
flowers,—the parts that appear first are the
cause of the appearance of those that follow
at later stages.
among inorganic bodies. When a crystal is
formed in the midst of a fluid, the particles
composing it unite, in conformity with the mere
laws of cohesion and affinity, not in consequence
of any determining influence in the particles
which cohered the first,—each stage or period
of the process of crystallization is independent
of that which preceded it. Whilst the parts

of an inorganic body, therefore, can exist with —
all their qualities, as well in a state of disin-—
tegration as in one of aggregation, the com-

ponent parts of organic bodies can only exist
with their distinguishing properties when united
to the entire being. Individuality in the or-

No relation of this kind exists —

ANIMAL.

ganic world, far from existing in the integral
molecule as it does in the inorganic, can only
be said to exist in the mass of integral mo-
lecules united into that congeries of organs
which constitutes a particular being. As a
consequence of this independence on the
one hand, and dependence on the other, we
find, that whilst im the inorganic world the
several parts may be modified without the
others feeling the influence of the change in-
duced, in the organic, implication of one part
and modification of one action are commu-
nicated to and manifested in the state and
actions of all the other parts.

Considered with regard to their duration,
the objects composing the organic and the
inorganic world differ essentially. In the former
this period is determinate and definite, and,
although it varies greatly, it depends in a great
measure On circumstances inherent in the in-
dividuals ; in the latter it is indeterminate and
indefinite, and when the objects composing it
cease to be, it is generally in consequence of
circumstances exterior to themselves. Organized
beings exist for a limited time and in oppo-
sition to many of the physico-chemical laws ;
unorganized beings exist indefinitely, and only
in harmony with the whole of these laws.
Organic beings continue to exist in conse-
quence of a kind of reciprocal action with
external things, and especially by virtue of an
incessant change and renewal in their con-
stituent elements. The very condition of ex-
istence of an unorganized body is quiescence ;
any new action between its molecules them-
selves, or between these and others external to
them, any addition to, or subtraction from, its
component parts, implies the destruction of its
individuality.

In the organic world, new forms result from
the actions of forms already existing, which
have the wonderful property of producing
others similar to themselves; and this in virtue
of no general physico-chemical law, but of
an especial power inhering in each organized
being individually. There is nothing like this
faculty of procreation or of generation in the in-
organic world. When a crystal is produced, it
is necessarily at the expense of one or of others
that have already existed, or of a combination
of the elements of these; destruction is here a
necessary preliminary to production, and the
process is simply one of re-formation, not of
genesis or creation. Neither in the re-forma-
tions of the inorganic world do we find that the

forms are always necessarily the same as those

which preceded them: the crystalline form
does not depend on the nature of the integral
molecules, Bat on their mode of aggregation
and number. In the organized world, again,
nothing is more certain and fixed than that the
form of the new being shall resemble that
which gave it birth.

The last distinction we shall mention under
this head of material composition and physical
qualities between organic and inorganic bodies
is, perhaps, less striking, though not less in-
teresting on that account: it is this,~that whilst

121

in inorganic bodies the composition is quite de-
terminate, in organised beings, although con-
stituting particular species, the composition
may present individual differences or modifica-
tions. These are designated by the titles tem-
perament, constitution, §c. There is no corres-
ponding modification recognizable in the in-
organic world.

From what has now been said, it appears
that organized and unorganized bodies differ
essentially from one another in their general
physical qualities and material constitution.
The form of the organized being is determinate,
and its outline is rounded or undulating ; its
size is limited ; its duration is temporary ; its
composition is an assemblage of heterogeneous
parts, of solids and fluids, arranged so as to
compose a variety of fibrous and cellular
tissues, and aggregates of organs or parts
differing from one another in their form, struc-
ture, and functions, but all nevertheless mu-
tually dependent one upon the other, and con-
curring to a common end,—the preservation
of the individual, which has place by virtue of
an internal activity denominated life, amidst
incessant changes and renovations of the
matter entering into its composition, and
the continuation of the species, which is a
genesis or creation, implying neither destruc-
tion nor alteration in the mode of being of
the individual or individuals from whom the
new formation springs.

Actions of unorganized and of organized
objects. — But form, size, material composi-
tion, duration, mode of origin, &c. are not
the only particulars in the history of or-
ganic and inorganic bodies which are capa-
ble of being contrasted, and in which differences
may be made to appear. —

All that exists is active ; every entity performs
actions, or manifests forces by which its own ex-
istence is continued, and by which it participates
in the various phenomena of the universe. Of
these actions or forces there are two grand
classes, the one general, the other special: the
first'are the physico-chemical laws which per-
vade space and include the universe; the
second are the vital laws, which embrace within
their dominion plants and animals, or things
organized and having life.

The most general of all the forces possessed
are those of attraction and repulsion, which
inhere in, and are manifested by, all existing
things, organic as well as inorganic. Every
object gravitates or has weight, coheres in its
several parts, exhibits chemical affinities, and
yields to the expansive influence of caloric.
Inorganic objects exhibit these general forces
alone, and are absolutely under their control.
Organized bodies are also subjected to the same
general forces; but they are often modified,
nay, they are sometimes even abrogated and
set at nought by vegetables and animals alike,
in virtue of the special powers inherent in
themselves. These special powers have, in fact,
the singular property of subtracting, in various
degrees, the beings they actuate from the in-
fluence of the general laws of creation. In-

122 ANIMAL: —

stead of obeying the universal law of gravita-
tion, vegetables, for instance, shoot upwards,
and propel their juices from the roots to the
leaves; animals also distribute their blood in
opposition to the laws of gravitation, and by
their powers of motion overcome the universal

hysical law that tends to fix them in one place.

he force of cohesion is not a merely passive
property in the organized as it is in the unorgan-
ized world, and the laws of chemical affinity
are especially set at nought both by plants and
animais, their constituent elements being even
generally united into combinations the con-
trary of those which these laws ordain. Animals
and vegetables are farther abstracted from the
general law of caloric, the more perfect of them
at least having a specific temperature, inde-
pendent of that of the medium which sur-
rounds them, and which varies in conformity
with changes in the peculiar actions of which
in them it is the product.

There is even a distinction between the
organized and unorganized world to this extent,
—that while the physico-chemical laws do-
minate the inorganic world rigorously, and the
bodies. that belong to it seem to have begun
to be as they continue to exist through, or in
harmony with, their prescriptions, no organized
body known has either sprung into being or
continues to exist through the agency of purely
physical or purely chemical forces. The whole
of the special properties of organized beings
consequently must be held to be effects of the
agent denominated /ife, and of the laws which
this agent originates. The organized world is,
therefore, a creation within a creation, a some-
thing superadded to the material universe and
to the generally pervading forces that keep its
parts in their places, and endow them with
what may be called their necessary pro-
perties.

Nor is it only whilst endowed with life that
organized differ from unorganized beings.
Many of the distinguishing and peculiar pro-
perties of these remain for a season at least
after life has left the organization it had built
up. The extensibility and elasticity of the
tissues of animals especially, were held by
the distinguished Bichat as even independent
of life, which he owned increased their energy,
but which he denied as their cause, seeing that
they continue to exist after death. These pro-
perties are undoubtedly peculiar, and are at
all events effects of forces which life has called
into play, both the tissues which possess
elasticity and contractility, and these qualities
themselves having been engendered under the
influence of vitality.

In these properties, forces or capacities of
action common to all the objects of nature,
unorganized as well as organized, we see the
objection to the old denomination of inert,
which was applied to one of the great classes.
Nothing that exists is inert or inactive; but
organized have an infinitely wider field of
action than unorganized bodies. Let us, in
illustration of this position, examine in succes-
sion the various actions by which bodies gene-

rally originate, continue their existence, un-

dergo such modifications as they present in the ©

course of their existence, and by which they
come to anend or die.

Origin.— Unorganized bodies, minerals for
example, commence their existence from the
instant that circumstances exterior to them-
selves detach them from the mass of some
other mineral, precipitate them from a state of
solution in a fluid, or bring their constituent
elements into a position in which they can
combine together. In this, it is evident, there
is nothing like generation, as the term is
applied to organized bodies, which all alike,
vegetables as well as animals, spring from a
molecule, an atom, which has once belonged
to, and which has proceeded from, a being
similar to themselves. Vegetables spring from
seeds, animals from eggs. Organized beings,
therefore, are engendered, their existence
is a consequence of that of other beings like
themselves ; and in their succession they
depend one upon another. Minerals, on the
contrary, have no powers of reproduction ;
they cease to be, if at any time they originate
another mineral, and they are individually in a
state of perfect independence.*

In the mode in which organic and inorganic
bodies continue their existence, there is also a
striking dissimilarity. In the inorganic world
we observe no actions tending to preserve the
individual, other than those which have pre-
sided over its formation: it continues to exist
through the continuing agency of the affinities
and of the attraction of cohesion which called
it into being. Animals and vegetables, on the
contrary, have special powers for their pre-
servation superadded to those by the peculiar

* It were long to enter here into the discussion
of what has been called equivocal generation, which,
if admitted, militates against several of the in-
ferences just deduced. It is quite certain that
infusions of any organized substance do speedily
become filled with animals distinct in their kinds
and lately shown to be much more complicated in
their structure than was long supposed. It is
almost as difficult to conceive that these infusory
animals proceed from eggs contained in the fluids
in which they appear, as to imagine that they
proceed from the combination, per se, of their con-
stituent elements. Did we incline to admit the
reality of equivocal generation, it is certain that
its occurrence must be referred to other than the
general laws of nature, with which we have al-
ready had occasion to show the laws of life to be
in opposition, much rather than in harmony. It
would be absurd to believe that these general
physico-chemical laws, absolutely inimical to life,
should at any time call it into being. Equivocal
generation being acknowledged, therefore, it would
seem necessary to infer a third. order of laws be-
sides the physico-chemical and the vital, the
nature of which is altogether unknown to us.
The number of creatures which were presumed
to owe their being to equivocal generation, has
been very much curtailed by the progress of science
in modern times ; and it is not impossible that the
mystery which still overhangs the genesis of the
infusoria may one day be dissipated, and their pro-
duction demonstrated to be in harmony with tho:
laws which are known to preside over the origin
of higher classes of vegetables and animals.

ee

ANIMAL. 123

agency of which they have been created.
Inorganic bodies exist through the absence of
all change in their interior; organized beings
exist by force of change: there are two pro-
cesses, one of renewal, the other of decom-
position, perpetually going on within them ;
they are continually appropriating from bodies
exterior to themselves a quantity of matter
which they have the singular faculty of ela-
borating into their proper substance, and they
have at the same time the power of withdraw-
ing portions of the matter which already forms
them, and rejecting these from their interior as
no longer fitted for their preservation. Vege-
tables, by means of their roots and their leaves,
draw from the earth and from the air materials
which they elaborate into juices fitted for their
nourishment, at the same time that they throw
off, especially by means of their leaves, a por-
tion of the matter which had been absorbed,
either as superfluous or as improper to enter into
their composition. In the same manner ani-
mals appropriate to themselves various amounts
of matter in the shape of atmospheric air and
food, from which they prepare a fluid proper
for their maintenance, at the same time that
they, by virtue of peculiar processes, with-
draw from their bodies such portions of mat-
ter as have already fulfilled their destination,
and cast them out under the form of excre-
tions. Organized bodies, consequently, are
preserved as individuals by a process of nu-
trition, a process which implies dependence
on other bodies, and alternate appropriation
and rejection of the particles of these; the ex-
istence of an organized being, in fact, only con-
curs with the presence and appropriation of
substances external to itself, with a perpetual
accession of matter on the one hand, and of its
rejection on the other, whilst unorganized
bodies are more certainly continued, as their
State of isolation or abstraction from all ex-
ternal influences is more complete. Organized
beings, in a word, continue to exist by virtue
of certain inherent especial powers; un-
organized simply by virtue of the general
powers that pervade the universe in harmony
with which they were originally framed.

The modifications undergone by organized
and unorganized bodies are peculiar and cha-
racteristic in each class. In the first place
modification or change is no necessary con-
dition to the existence of an unorganized body,
as it is of one that is organized. A mineral in
a state of complete isolation might remain
eternally unchanged ; a plant or an animal, on
the contrary, cannot be conceived as existing
for a moment abstracted from the universe
around it, and without undergoing change.
A mineral, in the instant of its formation,
acquires all the properties that distinguish it at
any after-stage of its existence; in plants and
animals, on the other hand, as we witness an
origin, so we observe a series of modifications
denominated ages,—they commence their ex-
istence, they increase in size, they attain ma-
turity, and they decline and ultimately die.

Any change which unorganized bodies ex-
hibit is accidental, and happens under the

influence of agencies external to themselves ;
the changes which organized beings undergo
in the course they run from incipience to their
end, are on the contrary necessary, and take
place in consequence of powers inherent in
themselves.

Any change which an unorganized body ex-
periences happens on its surface: its mass is
increased or diminished by simple addition to
or subtraction from its particles; it does not
increase, neither does it shrink and decay in
all its parts like plants and animals, in which
increase and diminution take place at one and
the same time from within and from without.
Increase in the unorganized world happens
through juxta-position, in the organic through
intus-susception. Organized bodies, conse-
quently, as they alone are generated, as they
alone possess powers of self-preservation and of
reproduction, so do they alone grow, advancing
necessarily from infancy to maturity and old
age, or exhibit what are called ages. (See AcE )
Organized bodies further meet our obser-
vation in two different states,—those, namely,
of health and of disease, nothing correspond-
ing to which is encountered in the inorganic
world.

Whatever has a beginning has also an end.
But the mode in which organized and un-
organized bodies cease to be, and the influences
that determine their periods of being, are ex-
tremely different. A mineral ends when the
affinities that combined it, and the attraction
of cohesion that held its particles together, are
overcome. This language implies that its
destruction is effected by agencies external to
itself—by the action of other bodies, and of
circumstances over which it has no controul.
The destruction of a mineral is, therefore, in
nowise necessary, neither is it spontaneous:
abstract a mineral, as we have said, from all
external agency, and its endurance is inde-
finite.

Very different is the case with regard to
animals and vegetables; as their continuance
depends on the process of nutrition, their end
hangs upon the cessation of this act; and as
the tenure by which they enjoy existence is
temporary, the machine of organization being
calculated to endure but for a season, their
death or destruction is both spontaneous and
necessary. Organized bodies which alone owe
their being to generation, which alone continue
their existence, reproduce their kinds, grow,
attain maturity, and become aged by virtue of
powers inherent within themselves, so do they
alone die.

The period of endurance of unorganized
bodies may often be calculated approximatively
according to their masses, their densities, the
aptitudes of their elements to enter into new
combinations, &c.; that of organized bodies
cannot be inferred from these or any other
merely mechanical principles. Indeed, data
from which the duration of organized bodies
may be estimated are altogether wanting. We
only know that every species has within nar-
row limits a period which it cannot pass; but
why this period should, in particular instances,

ae ANIMAL.

be confined to a few weeks, months, or years,
or be extended to centuries, we cannot tell.

Nor is it only whilst endowed with all their
peculiar and inherent properties that organized
differ from unorganized bodies. No longer
manifesting their especial powers, organized
bodies begin to be disintegrated ; their con-
stituent elements, held together in opposition
to the laws of chemical affinity, become ame-
nable to these, and forthwith enter into new
combinations, which imply the utter destruc-
tion of the organization as it had been formed,
and hitherto preserved. Organized beings, as
they alone die, so do they also alone undergo
putrefuction—a process nothing precisely si-
milar to which occurs in the inorganic world.

From this review of the distinguishing pecu-
liarities of organized and unorganized bodies,
it appears that organization implies vitality,
and that organization and life are insepara-
ble conditions. It would be going too far
to say that they were synonymous terms:
organization is the mode of structure proper
to living beings; life is the series of actions
they exhibit. And this in fact appears to be
about the least objectionable definition of life
than can he given: life is the series of actions
manifested by organized beings; would we go
farther, we must condescend upon an enumera-
tion of these actions, ’ ipi
a genesis or creation; temporary endurance as
individual by nutrition, and indefinite continu-
ance as species by reproduction, modification
during the term of existence known by the
title of age, and end by death, to which spe-
cific acts or phenomena must be added the
peculiar inherent power which living beings
possess of overcoming the general physico-
chemical laws that dominate the rest of the
universe.

Thus far we have discussed and contrasted
the physical qualities and phenomena common
to organized or living beings at large, with
such as inhere or are manifested by unorganized
bodies generally, more especially minerals; we
have still. left untouched those that severally
pertain to the two grand divisions of the or-
ganized world, and “that are peculiar to each
living thing individually ; and here we shall
find that the manifestations of vitality are al-
most as various as the species that people the
earth. In the same manner as we have hitherto
gone on contrasting first the material compo-
sition, and then the actions of organic and
inorganic bodies, we shall still proceed by
comparing the material composition and the
capacities of action of the different classes of
organized beings first, and next of the several
individuals composing these classes one with
another.

COMPARISON OF ANIMALS AND VEGETABLES,

Animals and vegetables were long held essenti-
ally and irreconcilably distinct from one another.
We have already had occasion, however, to
observe in how many particulars they are iden-
tical. The material composition of both is often
in opposition with the general physico-chemical
laws, both are made up of a combination of

solids and fluids, both consist of a variety of

heterogeneous parts, and both have determinate
sizes which they cannot exceed. Moreover,
both are possessed of vitality,—in other words,
both commence by a genesis, preserve them-
selves as individuals by nutrition, and as spe-
cies by reproduction; both grow by intus-sus-
ception, undergo the mutations which are
denominated ages, endure for a time, present
themselves in health or labouring under disease,
and both decay and die. How intimately ani-
mals and vegetables are associated, how nearly
they resemble one another, will farther appear
as we advance in the following

Comparison of the general physical qualities
and material composition of Vegetables and
Animals—As a general axiom the material
constitution of vegetables may be said to be
less complex than that of animals; this at least
is more especially the case as the individuals
at the top of the two scales are concerned.

No distinguishing feature of either class is
derivable from general diversity of Size. Be-
tween the microscopic lichen and infusory ani-
mal, and the gigantic adansonia and whale,
plants and animals of every intermediate mag-
nitude are encountered.

Neither is there much to be said upon the
differences which vegetables and animals pre-
sent when their Forms are contrasted. The
forms of many are alike amorphous, or simply
globular; certain pulverulent fungi in the one
class, and monads in the other, resemble each
other greatly. Among both, individuals also
occur whose parts are disposed around a centre ;
yet we do not advance far before we discover a
peculiarity in animals, namely, composition by
the union of two similar or symmetrical halves
along a middle line or axis, nothing similar to
which has even been imagined in the vegetable
world, the members of which on the contrary
often exhibit a horizontal division, but without
anything of symmetry, into root and branches.
As a general law the animal kingdom may be
said to affect the globular or simply produced
form, with radii in the shape of extremities
sent off from a central part; the vegetable to
exhibit a greater tendency to ramification or
division into branches.

In point of chemical composition animals
and vegetables consist very nearly of the
same elements: oxygen, hydrogen, carbon,
nitrogen, phosphorus, sulphur, iodine, bro-
mine, chlorine, potassium, sodium, calcium,
siliclum, magnesium, manganese, and iron
have been detected in both; aluminium and
copper have hitherto only been discovered in
vegetables, and fluor only in animals. But
these elements are united in each in very dif-
ferent relative proportions. Carbon predomi-
nates greatly in the more solid parts of vege-
tables, nitrogen in the bodies of animals gene-
rally,although to this rule there are many notable
exceptions ; albumen, fibrine, and gelatine all
contain much more carbon than nitrogen, and
certain fungi include a very large proportion of
nitrogen in their composition.
ments, met with abundantly in animals, occur
but sparingly distributed among vegetables,

Several ele-—

ey

>

ee ee

ANIMAL.

phosphorus, for example, and sulphur. The
earth afforded by animal bodies incinerated, is
mostly lime in a state of saline combination ;
whilst that yielded by vegetables, besides lime,
consists of alumina, with an admixture, greater
or smaller in amount, of scilica.

The peculiar combinations which form what
are called immediate principles, are much more
numerous in the vegetable than in the animal
kingdom, and are also generally more simple
in the former than in the latter, the immediate
principles of vegetables being mostly ternary
compounds, whilst those of animals are gene-
rally quaternary, nitrogen being added in these
last to the carbon, hydrogen, and oxygen, which
form the organic elements of the first. The
immediate principles in both classes are divided
into acids and oxides; and many of these they
have in common. Vegetables, however, have a
third order of substances entering into their
composition, of which we discover no traces
among animals; these are the vegetable sali-
fiable bases.

There are but few acids which exist in the
vegetable and animal kingdoms in common;
and whilst their number is small among ani-
mals, it is very great among vegetables.

The hydrocyanic acid has only been dis-
covered in vegetables; when it is procured
from animal substances, it is always formed un-
der peculiar circumstances, or during their de-
composition.

Of the organic oxides, some—albumen, osma-
zome, sugar—are common to both animals and
vegetables; but they occur in very different
proportions in each: sugar, which is so abundant
among plants, is scarcely to be detected among
animals ; and osmazome, which is so univer-
sally distributed among animals, has only
hitherto been discovered in afew fungi. Of the
ternary compounds of carbon, hydrogen, and oxy-
gen, such as starch, gum, sugar, the resins, woody
Sibre, fixed oils, volatile oils, camphor, extractive
matter, &c. which enter so largely into the consti-
tution of vegetables, there are but a very few
to be discovered among animals, such as the
sugar of the milk and urine, the resin of the
bile and of the urine, the elaine and stearine of
the fat, the volatile oily principle of castoreum,
&e. and the camphor of cantharides.

The quaternary organic compounds of car-
bon, hydrogen, oxygen, and nitrogen, which
form the principal elements in the composition
of the bodies of animals, are, on the contrary,
very rare among vegetables. ‘The most com-
mon of these are albumen, gelatine, fibrine,
animal mucus, and osmazome ; the less com-
mon enumerated are the matter of the saliva,
caseous matter, urea, and the pigmentary mat-
ter of the eye.

Still vegetables are not without several of
these quaternary compounds, such as albumen
and osmazome, and they even possess others
which are peculiar to themselves, such as gluten,
the matter of the pollen of flowers, indigo and
several extractive colouring principles ; to say
nothing of the whole exclusive class of salifiable

» quinia, cinchonia, veratria, strychnia,
morphia, &c., &e., which appear to be com-

125

pounds of carbon, united in large proportion
with a little oxygen, hydrogen, and nitrogen.

Comparison of the ‘organic composition or
texture of animals and vegetables.—We find
many and much more striking differences in
the texture than in the chemical composition
of the two great classes of organized beings.
Both are made up of solids and fluids; but
with a few exceptions, the proportion which
the solid bear to the fluid parts is much greater
in vegetables than in animals.

The fluids contained in the bodies of the
higher anima!s, the blood, chyle, spermatic
fluid, bile, urine, &c. have in general a very
different character from those that constitute the
sap of the more perfect vegetables, or that are
deposited as secretions in the nectaries and
various cavities of their flowers, leaf-stalks,
stem, &c.

But the solids, entering into the composition
of each class, are still more widely dissimilar
both in their outward and in their intimate
characters. The most simple vegetables, the
cryptogamia, appear to consist of a homo-
geneous tissue, forming rounded or oblong cells
filled with fluids or a granular substance, with-
out any trace of proper tissue; it is only:
when we come to the phanogamous vegeta-
bles that we find any distinction of tissues,
namely, a cellular and a tubular tissue, the
whole body of the plant being surrounded with
a distinct integument or bark.

The cellular tissue of vegetables, whilst still
young, is soft, homogeneous, and contains
cellules filled with a fluid often charged with
globules; when full grown, this tissue is made
up of cells properly so called, being spaces
surrounded with solid membranous parietes of
various forms and sizes containing different
matters. These cells appear composed of vesi-
cles placed side by side and running one into
another, surrounding the spiral and nutrient
vesse!s of the stem and bark, and opening so
as to form reservoirs filled with air, or resinous,
oily, or muc.laginous fluids.

The tubular or vascular tissue of vegetables
occurs under two different forms—spiral vessels,
and nutrient vessels. The former present
themselves in great abundance amidst the
woody fibres, but penetrate also into the leaves,
and even into the stamina, pistilla, and fruit.
They are not met with in the bark. These
vessels seem specially destined to include and
conduct the sap, which from the root ascends
to the extreme branches and leaves of all vege-
tables. The nutrient vessels, so called from con-
taining a fluid, the cambium or succus proprius,
different from the sap, prepared from this by
elaboration in the leaves, have now been demon-
strated in a great number of vegetables; they
are principally contained in the soft inner layer
of the bark, but they also penetrate every part
for the purpose of conveying the essentially
nutritive juice or blood of the plant.

These elementary tissues, combined and
arranged in a great variety of modes, constitute
the root, trunk, leaves, flowers, and fruit of all
vascular vegetables; and it is wonderful how
nearly the whole of this tribe, however dis-

126 ANIMAL.

similar in their outward appearance, resemble
one another in their intimate structure.

The tissues that enter into the composition
of animals are much more numerous than those
of vegetables. The most universally distributed
of these in the more perfect species of animals
are the cellular, the vascular, the nervous, and
the muscular, to which must be added the
tendinous or fibrous, the osseous, the cartila-
ginous, and the horny, which are less uniformly
diffused among the individuals composing the
animal kingdom.

The cellular is the tissue the most universally
encountered among animals; it is demonstrable
from the very lowest to the very highest. Its
general appearance is that of a soft, homo-
geneous, whitish, semi-transparent, extensible,
and during life slightly contractile substance.
It is permeable to air and liquids, and is easily
distended by either of these, when it forms a
series of continuous cavities or cells, strangers
at first to its constitution, but so readily pro-
duced as to have given the tissue its distin-
guishing title. The cellular tissue is dispersed
abundantly through every part of the animal
body ; it enters as a principal element into the
composition of many other tissues; it pervades
the innermost parts of almost all organs, and in
a modified shape forms a covering for them
externally ; it may be said to constitute the
frame-work of the organs generally, supporting
them in their particles as it does in their masses ;
it connects them together also, includes and
accompanies the bloodvessels that supply them
with nourishment, fills the intervals between
them, and establishes continuity between every
part of individual organized beings. The cellu-
lar tissue consists of filaments and lamina,
mingled and entangled together; the interstices
it contains, and which may be blown up into
cells, appear to be moistened during life by a
thin vapour, or a variable quantity of serous
fluid.*

The cellular substance appears to constitute
the element of the various membranes encoun-
tered in animal bodies : the fibrous membranes,
the skin, the mucous membranes, the serous
membranes, and the synovial membranes, are
all readily resolvable into cellular tissue; they
in fact appear to consist of this tissue in dif-
ferent states of condensation.

The vascular is another tissue extensively
distributed among animals. Three modifica-
tions of the vascular tissue have been reckoned
by anatomists, occurring respectively in arteries,
veins, and lymphatics.

The third tissue which is peculiar to animals
is the nervous. This may be held the most
eminently distinctive of this class of organized
beings, as it is by its intermedium that they
exhibit, almost all the faculties which place
them so immeasurably above vegetables in the

* Rudolphi assigns as a distinction between
animal cellular tissue and that of vegetables, that
the latter exhibits cells of a more or less regular
form with firm walls, nothing of which kind exists
in the former: Rudolphi Anat. der Pflanzen, S. 26,
ee in Tiedemann, Physiologie, Ister Band, S.

scale of creation, and as, generall ene.
they may be reckoned by so oe the more
perfect as particular portions of this system
are more fully developed. The element of
the nervous tissue is a soft, whitish, and
little consistent substance, composed of mi-
nute globules surrounded by a semifluid sub-
stance, and connected together by a tissue of
cellular membrane of extreme tenuity. The
globules are mostly disposed longitudinally,
when they form the medullary fibres of the
brain ; surrounded by denser sheaths, they take
the form of nerves. Inall the higher animals
at least, two orders of nerves are distinguished,
each, however, being intimately connected with
the other,—the nerves of animal, or, better, of
phrenic life, and the nerves of organic or vege-
tative life. The nerves of the first order are
connected in the higher classes of animals with
a brain and spinal cord; those of the second
proceed from small bodies of a reddish grey
colour, and irregular shape, named ganglions.
The functions of the first take place with con-
sciousness, those of the second without this
mental phenomenon.*

The fourth tissue peculiar to animals is the
muscular. In several of the very lowest tribes
of these, indeed, the existence of this tissue
cannot be demonstrated; yet its actions begin
to be manifested at a very low grade in the
scale. The element of the muscular tissue is
a fibre, on the ultimate constitution of which
there have been many disputes. The ultimate
muscular fibre would appear to consist of a
series of solid globules longitudinally disposed,
and connected into larger and larger fasciculi,
which at length compose the distinct bundles
denominated muscles. Fibrine is the organic
element of the muscular tissue. Its peculiar
and distinguishing property is its capacity to
contract or to become shorter, and to relax again
or return in its quiescent state to its first lentgh.

The muscles, like the nerves, are divided
into two classes or orders, the one under the
influence of the will, the other independent of
it. The texture is different in each of these
two orders: in the voluntary muscles, the fibres
and bundles of which the peculiar tissue con-
sists are very regularly disposed, and generally
in straight and parallel lines relatively to one
another; in the involuntary muscles again, the
fibres appear of different degrees of density,
run parallel or obliquely with regard to one
another, are superposed in layers, intermingled
and entangled like a kind of felt, &c.

* Some physiologists have gone so far as to
suppose a rudimentary nervous system among
vegetables, which would imply consciousness on
their parts of their existence. . This, at least, is
a very doubtful presumption, but we are not with-
out abstract arguments which might be adduced in
favour of the supposition. How immensely would

the sphere in which the bounty of, the Creator

had displayed itself then appear enlarged !
number of beings conscious of the joys of exis-
tence would be increased a thousand fold; and it
is even delightful to imagine these lower parta-
kers of organization with ourselves and animals,
also enjoying the light and sunshine, the sequence
of day and night, the freshness of spring, and the
fulness of autumn.

ian

oe et ee

ANIMAL.

The fifth tissue which prevails among ani-
mals is the fibrous. This is or may be divided
into the ¢endinous and ligamentous. These are
alike subservient to the muscular tissue and to
the function of voluntary motion. They con-
sist of fibrous, parallel bundles, of a white
colour and pearly lustre, of great strength, and
possessing little elasticity.

The sixth tissue which is peculiar to animals
(the first of those less universally distributed) is
the osseous. This forms the frame-work or
skeleton which gives form and fixity to all the
other parts entering into the constitution of the
higher animals. The essential organic element
of bone is a cellular net-work consisting of
gelatine, within the meshes of which certain
calcareous salts, the phosphate and a little
carbonate of lime especially, are deposited in
order to give them greater solidity.

The cartilaginous is generally reckoned as
the seventh among the elementary tissues of
animals ; it may and has been very properly
assimilated to the osseous: the bones are car-
tilaginous at first, and with the progress of
years many of the cartilages show a tendency
to, or do actually become, converted into bone.
The cartilages that cover the articular heads of
the bones are almost the only ones that show no
disposition to undergo this change. The organic
element of cartilage is gelatine.

The fibro-cartilaginous is a mere modification,
although an interesting one, of the cartilaginous
or rather of the fibrous tissue. The fibro-car-
tilages are very strong, and particularly elastic.

The horny and calcareous coverings of in-
sects, and the crustacea have uses corresponding
to those of the bones. The calcareous shells
of the mollusca, too, bear a certain, though
a very remote analogy to the skeletons of the
higher animals.

The horny or eighth tissue peculiar to ani-
mals might with propriety be reckoned among
the number of those that are very widely dis-
tributed. We meet with it in the epidermis of
man, and as low in the scale at least as the
molluses and annelides; it is the most universal
clothing provided by nature for the bodies of
animals.

So much for the simple tissues entering into
the composition of animals, to many of which
nothing analogous can be discovered among
vegetables. But these are by no means the
only solid elements that make up the aggregate
of animal bodies. The organs, as we entitle
them, for the performance of certain functions
so generally encountered among animals,—the
lungs, liver, stomach, kidneys, testes, ovaries,
&e., &c., are so many peculiar compounds of
the more simple tissues, occasionally with ad-
ditions denominated parenchyma, nothing cor-
responding to which has ever been discovered
among vegetables. These various organs are
associated in animals into groups, dénominated
systems, which severally tend to the accom-

lishment of the individual functions mani-
ested by the creature examined,—the teeth,
tongue, salivary glands, cesophagus, stomach,
liver, pancreas, and intestinal canal, constitute
one great and important system, subservient to

127

the conversion of food into nourishment, and
the preservation of the individual; the testes,
penis, vagina, uterus, and ovaries, in the two
sexes, compose another great system by which
the species is continued, and so on.

Besides these solids we have a great variety
of fluids, which in animal bodies subserve
various and important purposes: we have, for
instance, the general nutrient fluid distributed
to all parts of their bodies, denominated blood.
We have a variety of fluids prepared for aiding
or accomplishing the act of digestion,—the
saliva, gastric juice, pancreatic juice, and bile ;
we have various fluids as emunctories of the
worn-out parts and particles of the system,—
the perspiration and the urine; and we have a
peculiar fluid prepared as a means of con-
tinuing the species—the spermatic fluid. Fluids
corresponding in their destination to one or
two of these are also met with among vege-
tables, but there they are greatly modified.

Comparison of the vital manifestations, or ac-
tions of vegetables and animals.—In considering
generally the manifestations of vitality in vegeta-
bles and animals, we immediately become aware
of very distinct and peculiar tendencies in each
class. A disposition to produce diversity of parts,
and a symmetrical arrangement of these, are as
striking features in the acts by which animals
are evolved, as the opposite or a disposition to
reproduce to infinity similar parts without sym-
metry is a character inherent in vegetables. The
liver, spleen, heart, intestinal canal, panereas, and
vertebral column, are the principal asymmetrical
parts in animals; the organs of the senses, the
lungs, kidneys, testes, ovaries, lateral bones of
the head, and extremities, and the muscles, are
the principal symmetrical parts ; and these seve-
rally cannot be said to be repeated,—they only
exist in pairs, on either side of the mesial plane.
Such accessory and unessential organs as hair,
scales, feathers, &c. are the only ones that
are found repeated among animals. The very
opposite of this tendency prevails among vege-
tables; we find nothing like symmetrical ar-
rangement on either side of a middle plane, and
we see the same parts repeated again and again
to infinity, so that any single part, a branch, for
instance, becomes an epitome of the entire
tree.

Another peculiarity in the mode in which
the vital processes build up vegetables and
animals consists in the situation and disposition
assigned to the various organs entering into
their composition. Whilst in plants the whole
of the organs destined to the manifestation of
particular functions,—the leaves, flowers, sta-
mina, pistilla, roots, &c.,—are placed externally,
and their interior or trunk is a mere prop upon
which these parts are hung, in animals the
whole of the essential organs destined for the
preservation of the individual and continuation
of the species are concealed, so that their ex-
terior is the shell, their interior the receptacle
for the especial Jodgement and protection of
these.

Such diversity in the arrangement of the
parts composing vegetables and animals does
away with the necessity for the existence among

128 ANIMAL.

the former of any thing like those cen/ral organs
found in the latter, which, from the interior of
the body, and generally from the mesial plane,
send off radii of communication to-every atom
of the organization, and prove the media that
unite their several and ofien widely separated
parts into a whole. We discover nothing lke
prolongations from central organs—from a heart,
an artery, a stomach, and a spinal cord or
ganglionic system, among vegetables. Hence the
independence of the several parts of vegetables
one upon another, hence their susceptibility of
being multiplied by cuttings, and even of some
species arising complete from their leaves.

A third and very important peculiarity in
regard to the mode in which the vital processes
are performed in the animal and vegetable
kingdom is that many take place with cun-
scivusness or knowledge of their occurrence, in
the one, whilst they all occur unconsciously in
the other. In vegetables the whole of the
acts whose sum constitutes their vitality are
perfectly irresistible, and take place in them
without their knowledge, and uninfluenced by
their will. A great many of the vital acts, in-
deed, take place without consciousness among

‘animals also, such as the circulation of the
blood, the digestion and assimilation of the
food, &c., but the moment the animal passes
the sphere of its individual existence, whenever
it has to act beyond itself, we find conscious-
ness of the action superadded to the capacity to
act. The very lowest animals select their food,
search for and appropriate their aliment as it
presents itself to them; the most perfect vege-
table, on the contrary, absorbs irresistibly, and
without perception or will, the materials brought
into contact with its roots in the earth, and its
leaves in the air. The same wide differences
are apparent in the act by which the species
is continued: animals search for, and, by an
inherent virtue denominated instinct, implying
consciousness, distinguish the other individual
of opposite sex, of which they have need in
order to procreate their kind; in vegetables,
on the contrary, all is passive ; the pollen or
fecundating powder is projected or falls upon
the pistillum, or is even left to be brought into
contact with this part by accident, without
participation in the act, without consciousness
of or will in its performance.

These two last named manifestations, the
one subservient to the preservation of the in-
dividual, the other to the continuance of the spe-
cies, are accompanied with such circumstances
in animals as presuppose in them other two
peculiar faculties : these are perception and the
power of locomotion. To preserve themselves
as individuals and as species, they required
powers which should make themacquainted with
and enable them to establish relations between
their own bodies and the world beyond them.
By the faculty of perception, which may be
taken as synonymous with sensibility in its
widest acceptation, an animal is made aware
of his individual existence, as well as of that
of the material universe without him. This
faculty also takes cognizance of all the internal
sentiments, feelings, or desires of which by his

constitution he is susceptible, and which are
always in harmony with the part he is destined
to play in creation. Sensibility may therefore
be defined: the faculty by which impressions
from without as well as sensations, emotions,
and intellectual acts from within are perceived.
The ergan of this faculty is by universal con-
sent admitted to be the nervous system. The
faculty itself, as the above definition indicates,
is susceptible of being considered under two
heads: as the impressions perceived or percep-
tions come from without, or as they emanate
from within. ‘The organs of the senses are the
media through which external impressions reach
the percipient principle which resides in the
brain and medulla oblongata in the higher
animals, the nervous ganglia in the lower, and
these same parts are the instruments or elabo-
ratories of the internal sensations. Both of
these kinds or modes of perception were alike
necessary to the beings endowed with them.
The external sensations are the watchmen of
the system, admonishing animals of the pre-
sence of the objects they require for their pre-
servation ; the internal feelings, in like manner,
are centinels which admonish them of their
wants and lead to the employment of the organs
by which these may be supplied.

By the faculty of Zocomotion, again, an animal
accomplishes all the promptings of his inward
nature; he places himself in relation with
the beings and the things which he is ad-
monished by his instincts or internal faculties
are necessary to him for his preservation as
individual and continuance as species. Made
aware of his wants by perception, by the
faculty of locomotion he is enabled to minis-
ter to them. These two powers, let us ob-
serve, always exist together; the one, indeed,
necessarily supposes the other. Sensibility or
perception is the monitor, locomotion the agent.
Without perception locomotion could have sub-
served no end ; without some capacity of loco-
motion perception would have been a vain in-
heritance.

Vegetables evidently possess no power of
locomotion analogous to that inherent among
the higher animals,—where the seed falls there
the plant springs, there it attains maturity, and
there it dies. Neither do they manifest any
thing like sensibility in outward act that can
be ascribed to volition or consciousness: their
nature, in fact, made perception unnecessary to
them; and having no power of locomotion, it
would have been useless in the two great acts
by which organized beings minister to their pre-
servation as individuals and to their existence
as species. Still it is impossible to deny every

thing like capacity of outward motion to vege-

tables. Although they have no power of trans-
porting themselves over the surface of the earth

or through its waters like animals, many of

them exhibit motions in their leaves and flowers

in relation with the state of the atmosphere, —
and the diurnal revolution of the earth ; the a
sexual organs in several species move the one
towards the other; and about the foot-stalks —

and petioles of the mimosa pudica and other

plants we observe particular organs that con- 7

tract when stimulated, very much in the same
way as the muscular fibre among the higher
animals. Moreover, the motions by which the
radicle constantly seeks the ground or tends
downwards and the plumula shoots into the
air, that by which some of the higher phano-
gamous plants twist in spirals around objects
‘hear them, and by which all preserve one side
___ of their leaves towards the light, cannot be held
as accidental or merely mechanical acts. Seve-

ral genera of the conferve and tremelle even

exhibit such remarkable oscillatory movements

as have induced different naturalists and phy-
___ siologists to reckon them among the number of
the animals.

With all this, however, locomotion among
vegetables is a very limited power contrasted
with the faculty among animals. These exhibit
all the automatical motions of vegetables, and
have in addition a particular system, the mus-
cular, superadded to their organization, by which
_ many of the most important offices of the eco-
_ nomy are performed: not only instrumental
1m procuring the food by which they are main-
__ tained, but in putting into play the digestive
and respiratory apparatus by which the nutri-
tive juices are prepared and assimilated, and
finally distributed among the higher tribes to
every part of the body. ‘The existence of this
system is in fact one of the grand characteristics
of the more perfect animals. By its means
they react upon the external world and modify
it according to their wants; by its means they
guide their senses and enlarge the sphere of

their acquaintance with things beyond them-
_ selves; by its means they impress the air with
_ the tones and articulate sounds, or execute the
_ signs by which they make known the various
_ States of their affective or moral and intellectual
_ being to one another; finally, by its means the
_ Sexes approximate, and those acts take place
_ which lead to the engenderment of new indivi-
_ duals and the continuance of species.

____ The best informed among physiologists, how-
_ ever, do not confine the motions of all animals
to the act of the particular tissue we denominate
Muscular. The polypes and many even of the
_ Massy acalephs, to say nothing of the smaller
-infusories, rotifers, &c. though they move
_ freely, cannot be shown to possess muscular
_ fibres in their constitution; neither indeed can
Y any nervous system, upon which muscular
_ contractions and voluntary motion have always
~ been held dependent, be demonstrated in these
€reatures. It is consequently probable that the
_ Means by which spontaneous motion takes
m.. in these lower animals are peculiar, as
fi we must acknowledge the evident mo-
tions which occur under many other circum-
Stances in the world of organization to be.
___ But let us now turn to the special manifesta-
ons of vitality of the two great classes of
sanized beings we are engaged in examining.
_ these we shall consider in the following order,
_ which is also that we have adopted in contrast-
2 Ing the manifestations of activity of unorganized
and organized beings,—namely, origin or repro-
di een nutrition or self-preservation, changes
VOL. I.

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ANIMAL.

129

undergone during the period of existence, or
the ages, and death, or end.

OriciyN, or the acts by which species are con-
tinued.— Vegetables and animals alike derive
their origin from a birth or genesis accom-
plished in two different modes, either without
the concurrence of opposite sexes, or with such
a concurrence. When organized beings are pro-
duced without the concurrence of opposite
sexes, the parent either divides into several
pieces, each of which becomes an independent
individual, or throws out burgeons or_ buds
from its surface, which, being detached in due
season exist as self-sufficing types of the spe-
cies. When organized beings spring from the
concurrence of sexes, again, two sets of organs
minister to the generation, the one denominated
male, supplying a fecundating matter, the other
entitled female, furnishing a germ, which sub-
sequently to its impregnation by the male
organ undergoes a series of evolutions that end
in the issue of an individual resembling the
parents, and fitted by its own acts to preserye
itself and to continue its kind.

Both of these modes of reproduction are
common to vegetables and animals. Conferve
and polypi alike exhibit the first mode, almost
without a difference: buds or sprouts arise
from the surface of both; these adhere for a time,
acquire a certain size, and are finally detached to
become independent beings. Again, the polype
divided into several pieces, gives origin in each
of these parts to distinct polypi, exactly as the
cuttings of vegetables take root and grow into
perfect trees, shrubs, &c.

The second mode of reproduction—that by
the concurrence of sexes, or of organs deno-
minated respectively male and female,—is also
exhibited by vegetables and animal's indiffer-
ently; but there are numerous circumstances
distinguishing this manner of reproduction in
the two classes of organized beings. In the
first place, the sexual organs do not exist from
the earliest period, and during the whole course
of the life of vegetables, as they do in animals ;
the sexual organs, in fact, only occur among
vegetables at the time of flowering, and perish
whenever the end of their evolution has been
accomplished, never serving oftener than once
for the generative act. The sexual organs of
all animals, again, that live for more than
a year, suffice repeatedly for their office; and
if they are not required to accomplish this
oftener than once in the short-lived tribes, it is
probably from no inherent incapacity to serve
again, or any destruction of the organs them-
selves, but simply because the term of existence
of the organism of which they formed a part is
complete,-—-they perish with the system to
which they belonged.

Another grand though not an invariable dis-
tinction between vegetables and animals is the
mode in which the sexes, or sexual organs—for
these may be taken as synonymous terms—are
distributed among the individuals of each class.
Speaking generally, it may be said that the
sexual organs are as commonly divided be-
tween ¢wo individuals among animals by whom

K

130

<

the species is represented, as they are confided
to one among vegetables, which is, therefore,
singly the type of its kind. In both classes,
indeed, there are exceptions to this general law:
the flowers of all vegetables do not contain
stamina and pistilla, or male and female organs,
neither are the opposite sexes invariably repre-
sented by two different individuals among
animals. In many plants the male organs are
known to exist in one flower, the female in
another, but both developed on the same
branch ; in many others, again, they exist on dif-
ferent stems, and are often evolved widely apart
from one another. In the same manner, many
of the lower tribes of animals include within
their individual organisms male and female
organs; this is the case with several tribes of
the genus mollusca, gasteropoda, the helix,
limax, and lepas, for instance, with the whole
of the extensive classes of the annelida, en-
tozoa, echinodermata, &c.

But though there be resemblance to this
extent among vegetables and animals in regard
to organs, in the act by which fecundation
is accomplished there is a wide and essential
difference; for whilst vegetables impregnate
themselves, or, rather, whilst the impregnation
of vegetables is a purely passive process, with-
out perception of or concurrence in its accom-
plishment on their parts,—the pollen of the
anthers of those flowers that have male and
female organs being simply shed upon the
pistilla, the impregnation of animals, so far as
our knowledge goes, appears to be almost as
generally a consequence of a connexion be-
tween two different individuals, and of volition
with consciousness on their several parts.
Although many animals have both male and
female parts included within the same organism,
it would seem that comparatively few have the
power of impregnating themselves: two in-
dividuals of the like species meet, and give
and take reciprocally ; so that there is, in fact,
much less difference between the highest and
the lowest tribes of the animal kingdom in the
essentials by which races are continued, than
at first sight appears, much less certainly than
there is between the vegetables and animals
that are most nearly allied. The modes in
which fecundation takes place in vegetables at
large, and in animals probably without exception,
are inherently and essentially distinct : an her-
maphrodite animal is still a very different thing
from an hermaphrodite flower.

Another difference between vegetables and
animals, less important, indeed, but still in-
teresting, lies in the number of the organs pos-
sessed by each destined for the continuation of
the species. In many vegetables the organs
are single, one flower being taken as a repre-
sentative of the sexes; in a much larger pro-
portion of plants, however, the organs are mul-
titudinous. Among animals, on the contrary,
with a few exceptions in the very lowest tribes,
the asterias, &c. where they are multidinous,
the essential male and female organs, the testes
and ovaria, exist singly or in pairs only.

A third diversity, and one that is striking

ANIMAL. es

and almost universal, between those species of
plants and animals in which the sexes are
represented by two individuals, lies in the
difference of conformation, size, and general
character of the individuals in the one class,

and their perfect similarity in the other. There

are very few diccious plants the males of
which are distinguishable from the females ;
there are very few tribes of animals, on the
contrary, in which the distinction of sex is not
extremely apparent, the males being generally
larger, stronger, and more courageous; the
females smaller, more delicately formed, and
more timid in their disposition.*

A fourth distinction which deserves to be
noted betwixt animals and vegetables is in the
diversity of the act by which the new being
is separated from the parent, and commences
its independent existence. The period at which
this happens, indeed, is determinate, and fixed
in both alike, but it is accompanied with con-
sciousness among animals, whilst it is alto-
together unwittingly accomplished among ve-
getables.

From this review of the mode in which
animals and vegetables are called into being,
or of the acts which lead to their creation, the |
main and most striking differences observable .
in the two classes are these: whilst in vegeta- ;
bles the whole of the acts that constitute re- .
production,—the union of the sexes, the fe- '
cundation of the ovum, and the birth of the
new being are accomplished without the will
and without the consciousness of the indi-
vidual, but irresistibly and necessarily, they
are left in some particulars, at least, to the
will, and take place with the consciousness
of the individuals among animals. i

Nutrition, or the acts by which the indi-
vidual is preserved.—Every thing in nature
changes, and organized beings only con-
tinue their existence with their aptitudes
to manifest the acts that draw so wide a
line of demarcation between them and unor-
ganized bodies, by a perpetual renewal or re-
composition, and as incessant a rejection or
decomposition of their elements. Nutrition is,
therefore, at least, a two-fold act, implying
absorption or appropriation of nutritive matter,
and excretion or rejection of the old and worn-
out particles that have already served their
office in the economy: it consists, in fact, as
we have said, of an incessant decomposition
and reconstruction of the fabric of the living
organized being. Nutrition, however, is a very
comprehensive term, and includes the whole of —
the vital acts by which the individual continues

* One of the most striking exceptions to this law —
occurs among some especially of the smaller sper (a
of the birds of prey. In many of these the female ~
is much more powerful, heavier, and even more —
courageous than the male. The care of the off-
spring, by one of nature’s ordinances, devolving
principally upon the female, the supply of f
for the brood—a supply procured by violen
might often have failed had she not in the
tribes been provided with superior

courage to insure its regularity and abundance. — a

its existence,—namely, among the higher tribes
of living things, the absorption or ingestion of
food or alimentary matter; the preparation of
this food by the processes of digestion and
respiration; the distribution of the nutritive
matter fitted for its ends, to every part of the
system by means of a circulation; the conver-
sion of the nutritive matter into the solids
and fluids or proper substance of the indi-
___ vidual, and finally the depuration and rejection

of the worn-out parts and particles by means

of certain secreting organs. These various pro-
: cesses in themselves will be particularly con-
___ sidered in the article Nutrition, to which the
_ reader is referred. Meantime let us contrast
__ these different functions as they manifest them-
selves in each of the two grand divisions of
the organized world.

Assumption of aliment.— The earth and
the atmosphere, and the carbonic acid
and water they contain, are the sources
whence vegetables derive their food. Here
they find aliment ready prepared for their use,
or rather, as passive agents, they depend on
the earth and the atmosphere for a supply
of the elements required for their continuance.
__ Those physiologists are now admitted to have

been mistaken who supposed that the food of ve-
_ getables was furnished by the inorganic earth,
air, and water, with which their roots and
leaves are in relation; more accurate experi-
ments have shown that plants are as dependent
as animals on supplies of substances that have
once had life for their support. When plants
_ are made to grow in pure earth and in distilled
_ water, they appear to do so by a kind of de-
_ composition of themselves, one part perishing
_ and affording food to that which continues to
_ live. To base a distinction between animals
and vegetables, consequently, on the presump-
tion that the one lived on organic, the other on
_ Inorganic substances, was incorrect: animals
_ and vegetables are alike in this respect ; both
_ feed upon organized matter, and this not al-
| Ways or necessarily in a state of decomposition,
_ a8 we observe among parasitic tribes, which
_ Subsist on the living juices of the individuals
‘they cling to. The food of animals, however,
= be stated generally to be both more various
and also more complex in its chemical com-
position than that of vegetables, and whilst
_ vegetables take all their food in a liquid shape,
_ animals much more commonly live on a mix-

ture of solids and fluids.

____ The assumption of food by vegetables and
_ animals takes place under very different cir-
cumstances. In vegetables it is necessary and
independent of the individual; it is also in-
_ cessant ; and, farther, it takes place from the
external surface, inasmuch as it is with this
_ that the materials which supply the nutriment
_ are in contact.
____ Animals, however, have not generally their
_ food prepared for their use brought into con-
___ fact with their bodies, neither are they passive
_ in its assumption; they have mostly to search
& for it abroad, and are provided with special
| _ Organs for this purpose. The act by which
| they take it is not necessary, neither is it in-

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ANIMAL.

131

cessant. They have also to select their food,
and are, therefore, furnished with faculties’
which guide them in their choice; namely, taste
and smell. Lastly, the absorption of the truly
nutritious matter is accomplished from their
interior, the crude material assumed as food
having been first prepared by elaboration in a
cavity called a stomach.

As organized living beings, the soundest
philosophy and best ordered experiments lead
us to infer that there is little if anything me-
chanical in the mode in which either vegetables
or animals absorb nutriment. The absorption
of their aliment by vegetables is influenced by
the seasons, their state of health or disease,
their age, and external circumstances gene-
rally,—the temperature, state of dryness or
moisture, &c. of the air with which they are
surrounded; the cause of the absorption of
their food by vegetables is, therefore, some-
thing different from what is called capillary
attraction, or the law by which fluids ascend
in tubes of small calibre.

The proper passage of the nutriment into the
bodies of animals occurs from their interiors,
and in a very large proportion (probably in
every somewhat perfect member) of the class,
by means of a special set of vessels denomi-
nated lacteals or lymphatics, no system cor-
responding to which exists among vegetables.

The very lowest tribes of the animal king-
dom, the entozoa, acalephe, polypi, &c. having
no proper vessels of any kind, the cellular
membrane of which they consist absorbs, and
by virtue of a peculiar vital process, distributes
the nutritive juices extracted from the matters
received into the stomach and alimentary canal
to all parts of their bodies. Those tribes of
animals which have naked skins have the faculty
of absorbing by their exterior also.

Still less than in vegetables, can we suppose
that the process by which in animals nutriment
is ultimately absorbed into the body, whether
from the exterior or the interior, is akin to
mechanical or capillary attraction. The tissues
of which animal bodies consist are, indeed,
permeable to fluids, but this does not explain
the collection of these fluids in so many tribes
into particular canals, and still less does it
solve the problem of the continued motion
onwards in determinate directions within these
channels.

Absorption of alimentary and other matters,
therefore, in both of the grand divisions of the
organized world, must be held as a vital act,—
as one of the particular laws superadded in
organized beings to the general system of phy-
sico-chemical ordinances that rule the universe
and its parts. This quality is common to
vegetables and animals.

By far the greater number of animals have
one or more special openings,—a mouth or
mouths, by which they take in such sub-
stances as are fitted for their nourishment.
Even the greater number of animals as low in
the scale as the infusoria, have been recently
demonstrated (by Ehrenberg) to be provided
with an opening of this kind. Several, how-
ever, seem to receive aliment by the way of

kK 2

132

absorption alone. The mouth is a cavity of
extremely varied character and construction
adapted universally to the circumstances in
which animals exist. Nothing analogous to a
mouth is met with in any vegetable.

The food having been selected and seized is
next transferred to the cavity in which it un-
dergoes an elaboration that fits it to be received
into the proper system of the animal and con-
verted into its own substance. We do not
find anything like the pouch denominated a
stomach in any member of the vegetable king-
dom. The matter fitted for its nourishment,
absorbed by the root, is transmitted to the
stem, and from thence makes its way into the
leaves of the vegetable. It does not pass un-
changed, however, from the earth into the root,
or at least it has advanced but a very short way
on its course to the leaves, before it is found
to have undergone certain changes, which are
also known to be greater in amount as it is
examined at a greater height or distance from
the root. Although growing from the same
soil too, the sap of vegetables, i. e. the fluid
which is passing upwards through the woody
fibres, is found to be universally different.
Whether the peculiar qualities thus acquired
by the simple moisture holding certain salts,
&c. in solution, which is the food all vege-
tables derive through their roots, be the effect
of vital elaboration within the cells of the
woody fibre, or result from an admixture of the
cambium or fluid which has already undergone
assimilation in the leaves, is still uncertain.
We are inclined to believe that a process ana-
logous to digestion does actually take place
within the woody conduits of the sap of vege-
tables ;—why should it not, or why should
any new properties acquired by matters sub-
jected to the influence of the peculiar laws
of vitality be held as resulting from mere ad-
mixture ?

The very same thing, in fact, happens among
the lowest tribes of animals which takes place
in all vegetables: the substances fitted for their
nourishment penetrate or are absorbed into
their systems, and are there assimilated without
the intermedium of any special apparatus.
We mount but a very short way in the scale
of the animal creation, however, before we
meet with a peculiar pouch, destined for the
reception of the aliment, and accomplishment
of the first steps in the processes by which, in
the more perfect animals, it is finally assimi-
lated. This pouch is the stomach, and with
the rest of the digestive apparatus with which
it is connected, is in intimate and uniform re-
lationship with the kind of food upon which
animals are led by their instincts to live.

All the accessaries of the assimilating cavity
or stomach which we find in animals, from
the organs of sense that guide them in their
choice of aliment, to the lips that seize it, the
teeth or jaws that bruise it or destroy its
vitality, the muscular actions by which it is
swallowed, and the chemico-vital processes by
which it is dissolved, and the purely vital sen-
sibilities by which such parts as are proper for
nourishment are retained, and such as are im-

ANIMAL. :

‘distribute for the

proper for this purpose are expelled,—all of SS
these are wanting among vegetables. “ETO ae

There are yet other processes which form an __
essential item in the acts by which organized
beings universally continue their existence,
which it is necessary we should include in this
summary of the common, particular, and dis-
tinguishing attributes of vegetables and ani-_
mals. One of the most important of these is

Respiration—The leaves in the more per-
fect vegetables are the instruments of respi-
ration; their place is supplied by the general
surface in those plants that are aphyllous. Vege-
tables that live in air act immediately by
means of their respiratory organs upon the
ambient medium; those that live in water,
upon the air held in solution by the fluid
around them.

Vegetables are well known to exhale abun-
dantly from the surface of their leaves, or
stems, in case they have no leaves. The mat-
ter exhaled is principally water. They have
also the farther property of decomposing one
of the elements of atmospheric air, namely, —
carbonic acid gas. In the sunshine the leaves
of vegetables fix the carbon which enters into
the composition of this gas, and. set the oxy-
gen at liberty; in the dark, however, a very
different process goes forward; they then
actually absorb oxygen and exhale carbonic
acid gas; the balance, however, in the aggre-
gate is not equal between these opposite pro-
cesses, a much larger quantity of carbon being
fixed by the decomposition of carbonic acid
gas and oxygen set at liberty, than there is of
oxygen absorbed and carbonic acid gas set free.
These acts are essential to the life and health
of vegetables ; their end and object appearto
be the preparation of their proper nutritive
fluids or cambium: the sap which reached the
leaves, colourless, not coagulable, without glo-
bules, mere water holding carbonic acid,
acetic acid, a muco-saccharine matter, and
various salts in solution, is in them converted
into a greenish fluid, partly coagulable, and
full of globules, which special vessels then
growth and maintenance of

j
ao Lee

the different parts.

The respiratory act is necessary, and goes on
without the aid or concurrence of the indi-
vidual among vegetables.

Animals are no less dependent than vege-
tables on communication with the air of the
atmosphere, either immediately or mediately,
for a continuance of their existence, or the
manifestation of those acts whose sum con-—
stitutes their lives. In the very lowest tribes —
the communication between them and the air —
of the atmosphere takes place over the surface —
of the body generally, without the intermede |
of any particular organ or organs for the pur-
pose. The fluids absorbed into their bodies —
are brought into contact with the atmospheric
air in those points where they approach the
external surface, and there appear to undergo
the changes necessary to fit them. for being
converted into the substance of the animals
themselves. Simple as this process may ap-

pear, slender as the means of accomplishing it
May seem to be, it is nevertheless essential :
interrupted for any length of time, the animal

inevitably perishes. A process of such im-

_-_—s~éportance, as may be imagined, is not long left

without its appropriate and special apparatus.

This varies extremely in its structure, in the

different tribes of animals, and according to the

circumstances surrounded by which they live.

Some have lungs, branchie or gills, and

trachee opening by spiracula, of infinitely va-

ried construction.

_ Respiration is also carried on vicariously
in avery large proportion of animals, if not
_ perhaps in all to a certain extent, by means

of the skin, and in some even by the instru-

_ mentality of the alimentary canal.
__ The changes effected in the atmospheric
air by the respiratory apparatus of all animals
are similar, but they differ from those that are
produced by the corresponding implements in
_ vegetables: the proportion of oxygen it con-
_ tains universally diminishes, and the quantity

_ of carbonic acid gas it holds in solution as

_ invariably increases in amount. A quantity of

water or of watery vapour is at the same time

_ thrown off. This is exactly the opposite of

_ what we have seen to be the effect of respi-
_ tation among vegetables ; in these the quantity

of oxygen is augmented, whilst that of car-

_bonie acid gas is diminished. The nutritive

fluids newly prepared by the apparatus of

digestion, or that have already gone the round
of the system, are by a variety of means ex-
| , in the special or common apparatuses
‘Mentioned, to the influence of the atmospheric
air, from the contact of which they undergo
certain important and often manifest changes
‘that fit them for their ultimate office in the
animal economy,— the maintenance of its
parts, with their inherent capacities to execute
the various functions imposed upon them.

a respiratory act among animals takes
dlace with the knowledge and with the assist-
ance and implied will of the individual.
_ Animals are informed of the necessity of re-
Spiring by the feeling of a want, an uneasiness,
just as they are admonished of the necessity
of taking aliment by the painful sensations
denominated hunger and thirst.

_ The essence of respiration in the two grand
classes of organized beings would therefore
appear to be different, and might be made

o
f *

+.

the ground of a definitive distinction between
the members of each kingdom. Carbon is the
__ Object for which the respiration of plants is
| _Imstituted; oxygen the end for which re-
tions are established between animals and the
atmosphere. Another grand difference be-
yeen the respiration of plants and animals is
he involuntariness of the act in the one, and
its voluntariness in the other, its occurrence
vith unconsciousness in the one, and with con-
siousness in the other.

Th ®@ nutrient juices thus prepared have
now to be distributed ; this is done by means
a peculiar motion impressed upon the fluids

virtue of a vital law with the nature of

} ANIMAL.

133

which we are still very imperfectly acquainted.
Let us use the word circulation in a sense
implymg motion generally, not motion ina
circle to designate the act by which in the
organized world the nutritive juices are dis-
tributed through the frames of the objects
composing it.

Circulation.—There can be no doubt of the
existence of a circulation among vegetables ; in
many species currents in opposite directions
have even been seen with the aid of the micro-
scope, and this not only among the lowest and
most simple in their structure of the class, but
also in the highest and most complicated. The
circulation of vegetables appears to take place
within two different congeries of vessels, ex-
tremely numerous, and disposed according to
their nature in different parts of the plant. The
vessels that pump or transmit the sap from the
roots to the leaves, for instance, as we have
already had occasion to state, run within the
woody parts of plants; those that receive the
modified juices of the leaves, again, take their
course downwards within the bark. These two
sets of vessels anastomose within the substance
of the leaves, but no where else; the second
set can alone be said to have a distribution
throughout the vegetable, for every part appears
to depend on them for its supply of nourish-
ment, even the extreme points of the roots,
which were themselves the first instruments in
collecting the aliment still unfit for the purposes
of nutrition. The best informed vegetable
physiologists are of opinion that the nutritive
fluid once sent off from the leaves never finds
its way back to these organs again; it is ab-
sorbed or fixed by the different parts or struc-
tures to which it is distributed, ministering to
their increment generally, and enabling each to
manifest its specific function in the vegetable
economy.

In this motion of the fluids of vegetables it
is evident that there is little analogous to what
we find within the bodies of animals somewhat
elevated in the scale. But let us first cast
a hasty glance at what does take place within
this other division of the organic kingdom be-
fore instituting a comparison between the func-
tions of circulation in the two. All animals,
from the mammalia downwards to the entozoa,
—birds, reptiles, fishes, the mollusca, crustacea,
arachnida, insecta, and, among the radiata, the
holothurie, echini, and asteriz, include within
their organisms particular canals or vessels for
containing and distributing their nutrient juices,
and within which, moreover, these are in motion
inacircle. In the acalephe we still find canals
branching off from the digestive cavity and dis-
tributing the nourishment there prepared to the
different parts of the body: in these, however,
we no longer find any contrivance for establish-
ing a circular motion in the nourishing juices.
Still lower in the scale, among the polypes and
actinee, for example, we discover no branched
appendages or canals for the distribution of the
nutrient fluids; those prepared in the stomachs
of the animals appear to penetrate their sub-
stance directly, and to permeate the homo-
geneous cellular tissue of which they consist.

134

In the tribes which have a circulation, in
the strict sense of that word, we find two or-
ders of vessels,—arteries and veins, in which
the nutritive juices, or blood, moves respec-
tively in opposite directions, from the trunks
towards the branches in the one, from the
branches towards the trunks in the other.
These vessels anastomose freely by their ex-
tremities, which terminate and originate in
every part of the body, and, farther, meet in a
common central cavity, which, when furnished
with muscular parietes, is entitled heart. With-
in the circle of vessels thus established, the
nutrient fluid of animals is in perpetual or next
to perpetual motion during the term of their
lives. In the higher classes the main agent in
producing this motion is the central organ, in
which the veins and arteries meet; but it is not
the only cause of the circulation, this act going
on vigorously in circles and in situations

wherein the heart’s action can have very little”

influence, and in some tribes where the heart
is even altogether wanting.

The circulation in the greater number of
animals, however, is a more complicated pro-
cess than that which has just been described ;
it consists, in fact, of two parts perfectly dis-
tinct from each other; one whereby the blood
is exposed to the action of the air in the appa-
ratus which, in connexion with the respiratory
process, we have denominated lungs, gills, &c.,
another by which it is finally distributed for
the uses of the system. This double circula-
tion is accomplished by a great variety of con-
trivances (vide articles Heart and Crrevra-
TION). Insome tribes we find more than one
vessel,—two, or three, each apparently inde-
pendent of the other, though communicating
together, which are subservient to the distri-
bution of the nutrient fluid to the different parts
of the body of the animal.

The chief differences between vegetables and
animals with respect to their circulation, con-
sequently, appear to be these: in vegetables
the motion of the sap or aliment takes place
through the whole of one of the tissues of
which they consist; that of the cambium or
proper nutritive fluid through the whole of
another of these tissues, in opposite directions
simply, and by the intermedium of fascicu-
lated, very numerous, and independent vessels ;
whereas the aliment of animals does not cir-
culate through their bodies, but the nutritive
fluid prepared from it is collected and con-
fined within peculiar channels, connected at
both extremities in such wise as to form a con-
tinuous circle. In vegetables we perceive
‘nothing like tendency towards or distribution
from a central reservoir, nothing like ramifica-
tion from larger to smaller branches, &c.; coti-
sequently nothing like a heart, as we do in
-animals above the very lowest. In vegetables,
again, we see nothing like the two-fold distri-
bution of the nutrient fluid within different
orders of vessels, the one to the organs of
respiration, the other to the system at large, as
occurs among all animals possessing a some-
what complicated organization.

We have recognized the heart as the princi-

ANIMAL. -

conformity with the laws of vitality instituted
‘and probably originating and ending in livi

pal cause of the motions performed by the fluids
within the bodies of animals; but as neither
all animals have a heart and yet exhibit their
nutrient fluids in motion ; indeed, as a distinct
circulation of the blood may be demonstrated
in many animals, and probably takes place
in all at periods of their evolution anterior
to the existence of a heart; and further, as
vegetables exhibit a motion or circulation of
their fluids without the agency of any special
organ, it is necessary to acknowledge a new
law by virtue of which the fluids of organized
beings generally go their round or reach their
destination. This law has been designated as
the propulsive,—a power inherent in the nu-
tritive globules of living beings, and one of
the special laws superadded to the general and
all-pervading forces that regulate the universe.

One fundamental distinction between the
bodies of the organic and inorganic kingdoms
we have found based upon the permanence of
the parts, the constancy of the relations, affi-
nities, &c. of the component elements of the
one, and the incessant changes or renewals and
decompositions which these parts or elements
undergo in the other. The various processes
by which the aliment of vegetables and animals
is converted into a succus proprius, the final
means of their individual conservation and
evolution we have now examined; we have
only farther to discover this nutrient juice con-
verted into the different tissues and substances
of which organized beings consist, to have a
complete view of the vital act of nutrition.
But here we are compelled to pause. Of the
processes by which this transformation is ac-
complished we know next to nothing; all we
are assured of is, that each tissue and organ
seizes upon and converts into its proper sub-
stance those particles enveloped in the general
mass of circulating fluids brought into rela-
tionship with it, and which are adapted to this
purpose, at the same time that the particles
which have already been consolidated and
served their office are reduced to the fluid
state, absorbed back into the torrent of the
circulation, and afterwards either abstracted
and thrown out of the body by the operation
of certain organs charged with this duty, or
being subjected to the action of the atmos-—
pheric air in the lungs, gills, skin, &c. are
restored to their fitness once more to enter as
temporary constituents of the organization.
It is evident, therefore, that we are only ac-
quainted with this operation in its effects.
The act of ultimate nutrition has been happily
entitled one of continuous generation in eacl
living being and its parts; it takes place it

| 2

organized beings. oi

This subject, however interesting, we mu
reluctantly forsake, referring to the article ¢
Nutrition, and to the consideration of wh
has been called the nisus formations, or plast
power in our article on FaraL DEVELOPMEN’

Vegetables and animals, from this reviev

appear to differ little from one another in a

ANIMAL. 135

that regards their nutrition. The processes that
lead to this conclusion may be, and, indeed,
are more complicated among animals than
among vegetables ; but the essence of the final
act is very nearly the same in both. Neither
shall we be able to demonstrate any great
want of uniformity between these different
classes of organized beings in several of the
actions which we shall next discuss ; in others,
however, we shall discover an impassable line
of demarcation between them. The first of
these actions which we shall consider is

Secretion.—We have already had occasion
to mention the watery exhalation and oxygen
thrown off by the leaves of vegetables. _ Divers
other substances are excreted by the same parts,
—water, various acrid, glutinous, saccharine,
and balsamic substances. It is even by means
of the leaves that vegetables throw out those
substances which they may have absorbed by
their roots, and which seemed calculated to
injure them. We are at no loss, moreover, to
demonstrate numerous apparently glandular
organs in vegetables for the elaboration of a
variety of substances, many of them very acrid.
The flowers of vegetables secrete, in the first
place, certain matters, the infinite variety of
whose odours proclaims them to be different ;
the nectaries are also filled with fluids, which
are sweet in many tribes. Lastly, in the
flowers, the male fecundating matter, and the
fluid that moistens the pistillum are secreted.
Nor are vegetables without internal secretions,
among the number of which certain aeriform
fluids are not the least curious. The other
secretions of vegetables are of infinite variety,
—gummy, oleaginous, balsamic, camphoric,
&e. &e. These are all stored up in cells con-
tained in different parts of each individual
plant, and undoubtedly either subserve im-
portant purposes in their several economies,
with the nature of which we are very imper-
fectly acquainted, or are in relation with some
other system in the universe, affording food to
numerous tribes of insects, or materials which
stand in relation to animals and man as means
of accomplishing a variety of ends, the impulses
to which they bring into the world with them,
though they are launched upon existence un-
furnished with the materials.

We have also hinted at the watery and
gazeous products of the respiration of animals,
and consideration for a moment enables us
to make a long catalogue of other secretions
both with reference to individuals and to
- ee We have, for instance, the limpid

uids that bedew the cellular and serous mem-
branes, serum and synovia, and fill various
cavities in the body—the chambers of the
ear and of the eye particularly; those that
moisten and defend the surfaces of the mucous
membranes, the tears and mucus; those that
are subservient to digestion, the saliva, gastric
juice, pancreatic juice, and bile; those that
lubricate and prevent the surfaces exposed to
the air from drying, the sebaceous or oleaginous
fluids of the skin, and cerumen of the ears ;
those that are laid up as reservoirs of nutriment

or defences from the cold, the fat, marrow, &c.;
those that are ‘the vehicles for the worn-out
particles of the body, the urine and _perspira-
tion; those that minister to the reproduction
of the species, the fluids of the female germ
or ovum, the spermatic and prostatic fluids
of the male ; and finally, those that are poured.
out among the mammalia as the first aliment
for the newly-born being, the milk. Nor is
the list exhausted, for numerous species of
animals have peculiar fluids which are useful
to them in the places they hold in the system
of creation; among these are the venomous
fluids of serpents, and of the stings of numerous
insects, the inky fluid of the cuttle fish, the
fetid fluids of the anal glands of the carnivora,
rodentia, &c.; the fluid with which spiders
weave their web; the wax with which bees
build their cells, &c. Secretion is, therefore,
a much more extensive function among animals
than among vegetables; the products are still
more various, and the apparatus by which they
are eliminated is, generally speaking, far more
complicated among the former than among
the latter. Certainly, in the very lowest tribes
of animals, secretion is an exceedingly simple
process contrasted with what it becomes in the
higher, whose organization is more complex.
Among the polypi, meduse, and entozoa,
the whole of this function seems to consist in
a kind of transudation, or exhalation from the
surface of their homogeneous bodies, without
the intermedium of any special organ. Among
animals higher in the scale we find secretion
performed in two modes,—-by vessels, when
the act is entitled exhalation, and by means
of certain special organs named glands, an
arrangement which we also find among vege-
tables. The skin and pulmonary surface are
the great implements of exhalation among
animals, as the leaves are among vegetables ;
almost all the rest of the secretions take place
by the instrumentality of glands.

In vegetables secretion seems to be limited
to the preparation of the nutrient fluid by the
elimination of certain matters, and, so far as
our knowledge extends of the end to be an-
swered by any act, for the formation of the
generative fluids; we do not, in fact, find
among vegetables any apparatus set apart for
the excretion of matters derived from a change
in the constituent particles of the organs once
formed. Among animals, again, the apparatus
by which this depuration of the system is ac-
complished is one of the most important of all
to the preservation of the individual. Secretion
among vegetables is a function much more
under the influence of external circumstances
than it is among animals; it is also more sub-
ject to periodical changes among the former
than among the Jatter, and whilst the function
is mostly called into activity by the stimulus of
light, heat, &c. in the one, it rather obeys cer-
tain internal and peculiar stimuli transmitted
through the medium of the nervous system in
the other.

Like all the other special modes of activity
manifested by organized beings, secretion is

136

one of the products of the laws of vitality with
the essence of which we are altogether un-
acquainted,

Besides the secretion of the various gaseous,
fluid and solid matters mentioned, vegetables

and animals appear in common to possess the:

power of disengaging certain imponderable
elements—heat, light, and electricity.

Heat.—There has been considerable variety
of opinion among physiologists with regard to
the extent to which vegetables have the power
of maintaining a temperature of their own inde-
pendently of that of the surrounding media.
Nor is this question, in our opinion, yet com-
pletely set at rest. It is certain that trees in
high northern latitudes endure a cold many de-
grees below zero without injury, whilst in in-
tertropical countries they are frequently ex-
posed even in the shade to a heat above that
of any animal without perishing; actual ex-
periment, indeed, proves that they preserve a
temperature intermediate between that of the
extreme heat and extreme cold of the diurnal
variations of those latitudes in which they are
indigenous. This circumstance is explained
variously, some attributing it to a vital property
in plants to regulate to a certain extent their
own temperature, others alleging that it is
merely owing to the indifferent conducting
qualities of the materials of which vegetables
are composed. The thermometer has been seen
several degrees below the freezing point of
water within the trunks of fir trees, without
their vitality being affected; but it is probable
that the constitution of this tribe renders them
capable of enduring such a reduction of tem-
perature with impunity as would prove fatal to
other trees with simple watery sap.

On the other hand, it is quite certain that the
flowers of many vegetables have the power of
disengaging heat, a difference of ten, twenty,
and even more than thirty degrees having been
observed at sun-rise between the temperature
of the atmosphere and that of the flowers of
different vegetables in southern latitudes, and
the same thing is known to occur, though to a
less extent, in northern countries.

It would therefore be unfair, with such facts
before us, to deny altogether to vegetables the
faculty of disengaging caloric. Arguments, in-
deed, a priori, might be adduced to show that
they must almost necessarily possess such a
property: they are the subjects of incessant
change; and one of the most universal of the
physical laws involves a change of temperature
on any change of constitution.

If the faculty of vegetables generally to
secrete or eliminate caloric be doubtful, how-
ever, it is indisputable that among all animals
a little raised above those at the very bottom of
the scale, there is an inherent power of gene-
rating caloric, which in their state of maturity
is nearly determinate as regards each particular
species. Mammalia and birds have universally
the highest temperatures.

‘ Reptiles or cold-blooded animals, as they
are improperly called, have also the power of

ANIMAL. =
engendering heat, and of regulating their own

temperature: this faculty, however, and the

degree of heat they possess at different times,
are influenced to a very considerable degree by

the heat of the media in which they live. The
same statements may be made with regard to
fishes. The temperature of these creatures is
generally several degrees above that of the water

they inhabit; but it also varies with the tem-—

perature of their native element.

Many insects have a very decided
engendering heat and of regulating their tem-
perature ; and similar faculties have been de-
monstrated in the crustacea, the mollusea, and
the annelida. These tribes, however, are all
very much influenced by the temperature of the
media surrounded by which they live.

No great difference is therefore discernible
between vegetables and animals in the faculties
they possess of engendering caloric and regu-
lating their own temperature; the faculty is
only much more decided, and possessed to a
far greater extent among the more perfect
classes of animals generally than among vege-
tables at large. It may very fairly, in the
present state of our knowledge, be ascribed as
a common property.

As to the mode in which heat is engendered,
Opinions are still very much divided. The
chemical and mechanical explanations that
have been given of the phenomenon are not
universally applicable. All we can say at the
present day is that the production of heat and

the power of regulating their temperature pos-—

sessed by organized beings is another of the
hidden and singular laws or properties intro-
duced into the system of the universe with their
creation.

Light.—Many unorganized bodies have the
property of shining or giving out light for some
time after they have been exposed to the bright
rays of the sun, or have been heated in the fire,
or when they are struck together or smartly
compressed, and this certainly without any
decomposition of their substance. The disen-
gagement of light, again, is a very uniform
accompaniment of the decomposition and com-
position of inorganic substances, and it appears
to be a very constant attendant upon electrical
phenomena.

Various organic substances and products of
organization have a similar property; living
vegetables, too, particularly the flowers, have
been seen to give out light by authorities so
respectable, that though the fact has been
called in question by others of great name,
there seems no sufficient reason for treating all

that has been said on the subject as illusion :

in the physical sciences negatives cannot be
received as evidence of equal value with posi-
tives.

merable inferior tribes that live in the sea,
appear to possess and to manifest this pro-
perty at different seasons. ]
ness of the ocean itself, so familiarly known,

seems to depend on the presence of multitudes — 4

wer of

No one thinks of calling in question the —
luminousness of animals; most of the innu-

The luminous- |

>

“~<

—

ish th Ma ELLE NE oe RA ANE A

al Cn HA aS Ah ilehch iy AR LMR EN a Al ORE,

ANIMAL.

‘of infusory animals within its bosom. Many

wibes of insects shine in the dark. The phe-
nomenon is not certainly known to be mani-
fested by any of the class of reptiles, birds, or
mammalia. It appears to depend, in insects
particularly, on the presence of a peculiar
matter, secreted by their bodies and stored up
in particular points, which, under the influence
of a temperature elevated in a certain degree,
and the contact of atmospheric air, enters into
a kind of combustion daring which light is
emitted. Is the phenomenon dependent on
one common cause in both vegetables and
animals, supposing that it does really occur
among the former? -
Electrical phenomena are extensively ex-
hibited by the objects composing the unor-
ganized and the organized world. In fact,
wherever there is composition and decompo-
sition going on, there are electrical phenomena
manifested. The action of the immense mass
of vegetables on the air, the evolution of oxygen
in the sunshine, and the formation of carbonic
acid during the dark, has even been supposed
by an ingenious natural philosopher of France
(Pouillet) to be the principal source of the
electricity of the atmosphere.
Galvanic electricity is excited by the contact
of the different parts of which animal bodies
consist, particularly of the nerves and muscular
flesh ; the nerve of a frog’s thigh exposed and
isolated, touched with a piece of quivering
flesh from the body of a bullock just slain, also
isolated, causes the muscles to which the nerve
is distributed to contract energetically (Hum-
boldt). The same phenomenon occurs when
different other parts and fluids, particularly the
blood, are used to form a chain. But the
electrical phenomena manifested by animals at
e, are weak when contrasted with those
exhibited by certain fishes provided with spe-

cial voltaic piles or galvanic batteries by which

they give at will, but not otherwise, electrical
shocks of such violence as to stun larger ani-
mals and even to deprive smaller ones of life.
This electricity of animals must be held as a
vital phenomenon; several of them have in-
deed a peculiar apparatus for the preparation
of the shock, to speak of the phenomenon by

its effects, in our ignorance of its essence or

efficient cause, but this loses its power when
the nerves that are abundantly distributed to it
are divided. .

Electrical phenomena are not so obviously
displayed by any other tribe of animals as by

fishes; but it has been rendered next to certain
_ that muscular contractions are uniformly accom-

ied by a kind of electrical discharge from

_ the nervous fibrils distributed. to the special or-
gans of voluntary motion.

Animals, from this brief review, appear to pos-

sess electrical capacities in a much higher de-

gree than vegetables, in which the phenomenon
is even explicable on ordinary chemical prin-
ciples, whilst among animals it is unquestion-

ably one of the effects of vitality.

We have already indicated the existence of

_ two faculties among animals . which become

137

necessary or complemental to them as agents
entrusted with their preservation as individuals

and their continuation as kinds; these are
voluntary motion and sensation. But motion
in the abstract is a phenomenon of much more
extensive occurrence among organized beings
than the notion we form of the act as connected
with the existence of a muscular system. Mo-
tion is in fact a quality inherent in organized
beings; they cannot be conceived as existing
without change, and change implies motion.
In most, or indeed in the whole of the actions
which we have glanced at as manifested by
them, we have supposed motion. The simplest
of all animals, the infusoria, move about in
many cases with great briskness; the polypes,
composed of an uniform gelatinous mass, also
move in various directions ; the acalephs, with
a similar structure, rise from the bottom and
propel themselves through the waters of the
ocean by a succession of contractions of their
disc, of their tentacula, or of the fringe-like
or foliaceous bodies with which several orders
of the genus are provided. Many of the en-
tozoa too, whose bodies consist of a simple
gelatinous or mucous tissue, execute motions in
various senses.

But it is not only as a whole that a body
endowed with life and organization possesses a
capacity of motion. Many of its parts, and
particularly the globules which enter as essen-
tial and integral parts of the fluids contained
in organized bodies, have inherent powers of
motion ; the globules of the blood, for instance,
those of the spermatic fluid, and perhaps also
the germ included within the ova of the polype,
mollusc, &c., have all been observed in motion,
and the means by which it is accomplished
even demonstrated in many cases. But there
is nothing absolutely peculiar in such indivi-
dual instances, for we must need conceive
motion in the first constituent elements of all
organisms without exception, long before a
muscular, a cellular, a nervous, or any other
distinct system has existence.*

Motion of all kinds, therefore, automatic as
well as that which is voluntary, must be held
as a quality inherent in organized or living
beings. The cause of this phenomenon, as of
so many others manifested in the world of or-
ganization, has been the subject of much dif-
ference of opinion and of much dispute among
physiologists, and many titles have been ima-
gined by which the agent or primary cause of
the act has been sought to be designated, or
the act itself to be explained.

It is quite certain that the capacity to com-
mence and to continue the phenomena which
we designate as vital, or the motions which
constitute these phenomena, depends first on
a variety of external conditions, such as a

* Such motion is indubitable. The organic glo-
bule has capacities of motion inherent in itself,
different from the motions of unorganized objects
in a state of extreme division, as is proved by the
motions of each kind of body being different, and
those of organized globules being interrupted by the
electric spark, or whatever destroys their vitality
—acids, alkalis, poisons, &c.

138

certain temperature, intercourse with the air
of the atmosphere, supplies of aliment, and
the access of light, and it is indubitable that
organized beings exhibit phenomena that
may be designated excitability, irritability,
vital force, &c., which are only other names
for these manifestations; but it is also certain
that external conditions are of themselves ina-
dequate to originate manifestations of vitality,
and that the phenomena of living organized
beings, generally designated excitability, irrita-
bility, incitability, &c., are consequences of a
state of things to explain which they have been
conceived as causes, under the title of life,
vital principle, soul, &e. The term excitability
should be used in physiology, in the very
widest sense, to signify a property inherent in
organized matter generally, to be determined
to manifestations of activity under and in con-
formity with external influences (Tiedemann).
We in fact see organized matter of every de-
scription—the green matter of Priestley, con-
ferve, infusory animals, &c., acquiring organic
forms under the dominion of outward influences,
and every species of organized being existing
within a determinate circle of external agency.

It were a grave mistake to suppose this
agency either chemical or mechanical in its na-
ture; when of such potency as to act either
chemically or mechanically it is destructive
instead of productive of vital phenomena.
These phenomena, therefore, and external
influences are rather in opposition to one
another than identical. External influences ex-
cite organized beings to manifest their inherent
capacities; they do not bestow these capacities ;
all organized beings, indeed, and each parti-
cular tissue of every individual among them,
are excited in different modes by the various
influences from without; the stimulus is iden-
tical, the effects are infinitely different.

But organized beings, and especially ani-
mals, are not dependent on external influences
alone for the manifestation of their peculiar
properties; they have themselves the additional
power of engendering stimuli proper to arouse
into activity the various organs and systems of
which they are composed. The fluids circu-
lating through every part of their bodies may
be regarded in the light of the most generally
distributed stimuli of this description. The
nrevous system is another and important source
of excitation, the influence of which is felt in
every part of the organism of all animals above
the very lowest. The various instincts, appe-
tites, propensities, sentiments, and intellectual
faculties, also, which all emanate from the
nervous system, are inherent causes of a vast
variety of manifestations of activity among the
more. perfect animals. There are yet other
stimuli of a mechanical, or chemical, or pecu-
culiar nature, which excite unusual or ano-
malous manifestations; in this category may
be placed contagions of different kinds, the
causes of epidemic diseases, medicines, &c.

With regard to the essence or cause of this
property of the organic globule to commence,
and of the perfectly developed organism to
manifest the various phenomena whose sum

ANIMAL.

_

constitutes their vitality, and endows them
with their various cognizable properties, all we
can say is that it 2 Ae to inhere i i-
ately in the particular state of matter which
composes them. What this state is in itself
we cannot tell; but we are familiar with the
phenomena which ensue from, and which in-
deed reveal to us its existence. It is evidently
as diversified as species, and as the systems or
organs possessed by the individuals severally
composing these: there is a power—the nisus
JSormations, the vis plastica, in the matter sus-
ceptible of formation,—the organic globule, the
germ,—which presides over and regulates its
acts; and there are powers inherent in the parts
or organisms to which the plastic force gives
rise, in accordance with which they manifest
the special acts that distinguish them. It
would be improper, however, to regard this
power or these powers as forces apart from
and otherthan the globules, germs or organisms
themselves ; in the present state of our know-
ledge we cannot separate exciting causes from
manifestations of activity; all we can venture
to say is that germs exist, that organisms exist
with inherent capacities of action in harmony
with the peculiar states of their constituent
elements, thus: the germ of the infusory ani-
mal exists with its inherent capacity to en-
gender an infusory animal, the germ of the
polype with its inherent power to produce a
polype; in the same way the various tissues,
vessels, glands, &c. of vegetables and animals
exist with their special capacities of excitation,
which are manifested in the particular functions
they severally perform. Excitability is there-
fore a multiform property and a consequence,
not a single peculiar power inherent in orga-
nized beings, the fundamental cause of their
actions and identical with or itself the living
principle. Dependent on the integrity and
continuance of the functions of nutrition, how
can it be the cause of these? Only manifested
in kind, with the occurrence of specific organs,
how can it be the cause of their several ma-
nifestations ?

We are altogether in the dark with regard
to the mode in which the motions and other
actions of organized beings are performed, how
or by what law the globule that in the infusion
of organic matter is to become an infusory
animal moves, as well as of the manner in
which the contractility of a muscle is excited
by the stimuli fitted to call this quality into
action. The contractility of the infusoria, po-
lypi, medusz, and other similar tribes appears
to be peculiar. The motions exhibited by the
conferve, tremelle, and simplest vegetables —
are also peculiar to them, they differ from —
those manifested by the simplest animals in —
being entirely under the influence of external —
influences, and showing nothing like spon-
taneity. The tissues of all animals, even the —
most complicated, show traces of a vital ten- _
sion or contractility, different from simple
elasticity and not depending on muscularity; —
the cellular membrane, skin, fibrous tissues _
generally, excretory ducts, and vessels of all
descriptions tend to contract upon the parts

See ee oy oe Oe

SS Ss ot

:
.
)

ANIMAL. 139

and fluids they surround and include. ‘This
tonicity or peculiar contractility disappears
in great part with the cessation of life: a
wound made in a dead body never gapes as
it does in a living one. Something of the
same kind exists in vegetables; the sap as-
cends with greatly increased velocity in the
young shoots under the influence of stimuli of
different kinds, and its flow is checked by nar-
cotics and altogether arrested by poisons; it is
probable, therefore, that it takes place in con-
sequence of a vital tonicity or contractility in
the sides of the sap-vessels-which contain it.

From this general review of the physical
construction and vital phenomena of the two
grand classes of organized beings, vegetables
and animals, it is impossible not to remark the
strong features of resemblance, and yet the
numerous points of difference they exhibit.
Both have a beginning, which happens very
much in the same way in each; both live as
individuals by the susception of aliment and
its prepration by a variety of processes, which,
in their essence, differ but little from one an-
other ; both continue themselves as kinds ina
surprisingly similar manner; both exhibit the
changes denominated age; both have a merely
temporary existence, consequently both exhibit
the phenomenon entitled death, and both are
decompounded after the cessation of life, their
constituent elements assuming new shapes, in
obedience to the general laws of chemical
affinity, which had been set at nought during
the existence of the individuals in either class.

Notwithstanding these striking points of re-
semblance between vegetables and animals in
all that is essential or general, it is impossible,
as we have seen, to condescend upon _par-
ticulars without immediately detecting differ-
ences that distinguish in the most marked
manner the individuals of the one class from
those of the other. It is always in their lowest
or most simple species that we remark the
most striking similarity between vegetables
and animals, and it is among these that we
constantly find ourselves most at a loss for
characters distinctive of each. We observe no
evidence of anything like a connected chain
of being from the lowest or most simple, to
the highest or most complicated vegetable, and
from this through the most inferior animal
upwards to man ; it is, on the contrary, in the
extremes or lowest grades of each that the
greatest similarity prevails; here vegetables
and animals approximate very closely, here
they literally inosculate, but from this common
point they begin to form two distinct series,
which diverge ever more and more widely
from one another as they ascend. Without
attention to particulars, it would seem impos-
sible to adduce as ultimate terms of distinction
between vegetables and animals, other faculties
than those of voluntary motion and sensation
as peculiar to the latter, in virtue of the one of
which powers they are rendered in a great mea-
sure masters of their own existence, whilst by the
other they are endowed with consciousness of
many of the various acts that take place

within, and of the phenomena that occur
without them. Even this distinction, how-
ever, is only applicable as regards species con-
siderably raised above the lowest; would we
indicate the differences between the most in-
ferior members of either series we must con:
descend upon particulars, and, in some in-
stances, even call in analogy and inference to
our aid in laying down the chart of their re-
semblances and dissimilarities.

COMPARISON OF ANIMALS WITH ONE ANOTHER.

This head is also comprised within that of
our entire Cyclopedia. The glance we shall
cast over the field it embraces will, therefore,
be very cursory, aud the views taken of the
objects it presents extremely general.

Physical qualities and material constitution
of animals —In point of size, animals differ
most widely from one another. The existence
of some is only made known by the aid of a
powerful microscope, the length of others ex-
ceeds a hundred feet, and their weight amounts
tomanytons. These extremes include animals
of every intermediate bulk.

The form assumed by animals presents many
more interesting particulars for study and in-
vestigation than the mere bulk of their bodies.
The consideration of this accident has even
been made the ground of a classification of the
objects included within the animal kingdom
by several naturalists, and although not adopted
as the sole basis of any one now generally
received, it nevertheless furnishes the element
upon which several of the classes even of the
most recent are established. Some animals
present themselves in the likeness of a globule,
others of a filament, and others of a small
Jlattened membrane (the cyclides). Various
animals, again, from exhibiting no uniform or
regular shape, have been entitled amorphous or
heteramorphous.

Animals which exhibit a determinate form
naturally arrange themselves into two classes ;
their bodies are either disposed around a
centre, or they consist of two similar halves
cohering along a middle plane or axis; the
first are the radiata, the second the binaria
or symmetrica of naturalists. ‘The radiata are
not a very extensive class of animals, neither is
their organization extremely complicated. The
symmetrical is a much more numerous class
than the radiated, and includes within its limits
creatures of such simple structure as the en-
tozoa, and of such complicated fabric as quad-
rupeds and man. Of the symmetrical animals,
some consist of a mere trunk without appen-
dices or limbs; those that are provided with
limbs, again, have them in the shape of feet,
fins, wings, or hands, according to the media
in which they live. In some the body forms
as it were a single piece, in others it is divided
into portions, such as head, trunk, and tail.
Sometimes it is naked; at others it is covered
with shells, scales, spines, hair, &c. Some-
times the general integument is continuous,
unpierced by any opening that leads to the
interior, at others it is reflected inwards, and
lines extensive cavities there contained.

~

140

With regard to structure, as may be imagined,
the amorphous tribes, at the bottom of the
scale, are the most simple of all. The bodies
of some of these are without any internal
cavity, and without any division of parts;
they are homogeneous masses, generally gela-
tinous in appearance, and simply cellular in
structure, without arrangement into tissues or
particular organs. The external surface of
these animals imbibes the matters which are
fitted to subserve the purposes of nutrition,
and we may presume that it throws off by
transpiration such particles as are worn out
or have accomplished this end. The external
surface is also the organ of respiration in these
animals. ‘They procreate by the evolution of
gemmi from their surface, and if they possess
sensibility the element to which it is attached
must be generally diffused throughout their sub-
stance.

The organization of the radiata becomes con-
siderably more complicated. Fluids are no
longer absorbed from the external surface of
the body; we meet with an internal cavity, the
rudiment of a digestive apparatus, having a
single opening in some of the species, which
serves consequently for both mouth and anus,
but in others presenting two openings, a mouth
properly so called on one side of the body, and
an anus on the other. Through the walls of
this cavity the nutritive fluids make their way,
and infiltrate the general mass of the animal’s
body. In this class we also discover the
rudiments of a nervous and of a muscular sys-
tem. The nervous system consists of rounded
masses of a soft whitish substance, equal in
number to that of the radii composing the
animal, connected together by slender white
cords, and sending off filaments of the same
description to all parts of the body, but espe-
cially to the outer integument, and to the inter-
nal digestive apparatus. ‘The muscular system
consists of reddish and whitish fasciculated
fibres disposed in the line of the motions. The
external surface of these animals is still the only
organ of respiration they possess.

The three systems now enumerated—the
digestive, the nervous, and the muscular—are
readily demonstrated in the majority of the
symmetrical animals, and are even very soon
found to have acquired complication, and to
have sundry other parts and organs superadded
to them. ‘The digestive apparatus consists of
a mouth for the susception of aliment, of a
stomach for its elaboration, of an intestinal
canal from which the nutrient juices are ab-
sorbed, and of an anus from which the un-
digested residue is expelled. Whilst in the
radiata the nutritious fluids passed through the
parietes of the digestive cavity to impregnate
the body of the animal, and be assimilated
with its substance; in the binaria we find
vessels, the rudiments of a circulating system,
employed in receiving the juices prepared in
the digestive apparatus and transmitting these
to all parts of the body. _ Digestion, too, in this
class becomes a more complicated process than
in the radiata, and various secreted fluids,
saliva and particularly bile, the special products

ANIMAL.

of large and evidently important organs, are —
added to the alimentary mass in its progress
through the intestinal canal. sais

In addition to the digestive apparatus and
general exteinal respiratory surface we by-and-
by find an especial system dedicated to the
aeration of the juices prepared for nutrition;
this is the respiratory apparatus. Of extreme
simplicity in the first instance, being little
or no more than a fold of integument turned
inwards, and forming a simple cavity or sac
within the body of the animal, it is soon
rendered more complex in its structure, being
distributed in the manner of vessels under the
name of trachee or canals to different parts of
the body, or being confined to a particular
district, and entitled lungs or gills as it is fitted
to receive the atmospheric air immediately, or
to make use of this elastic fluid suspended or
dissolved in water.

The existence of this separate respiratory
apparatus presupposes that of another system,
namely, the circulatory. The fluids prepared
by the organs of digestion are not yet fitted to
minister to the growth and nutrition of the
organization; to be made apt for this purpose
they require exposure to the air in the lungs or
gills wherever these organs exist, and these be-
ing distinct, or contained in a particular region
of the body, a series of conduits were re-
quired, first to carry the fluids thither, and
to transmit them subsequently to every part of
the organization for its support. Like all the
other systems of animals, the circulatory exists
of various degrees of complexness; when first
encountered it consists of a series of simple
canals or vessels, which diverge on every hand;
by-and-by it has several, and finally one, forc-
ing piece, or heart. superadded to it, which
impels the fluids by its contractions to every
the most remote part of the organization.

Among animals, however, nutrition is not a
process simply of addition or composition ;
it is also, perhaps universally, one of subtrac-
tion or of decomposition. We have seen the
composition provided for by special systems
in animals occupying very low grades in the
scale of creation; we mount but a short way
before we encounter an apparatus which pre-
sides over the decomposition also in the shape
of another system of vessels, the veins and
especially the lymphatics ; these collect the
superfluous and worn-out particles from every
part, pour them into the general current of the
circulation, wherein being exposed in the vital
elaboratory of the lungs they are either assi-
milated anew and made fit once more to form
an integral part of the organization, or, being
subjected to the action of certain glands, they
are singled out, abstracted, and finally ejected
from the system entirely. In the most com-
plicated animals therefore a peculiar appa-
ratus for the depuration of the system is su-
peradded as complementary to the absorbents.
This we find in the glandular bodies familiarly
known as the kidneys ; the vehicle in which the
decayed particles are withdrawn is the urine. —

When we examine the instruments of sensa-
tion, we find them becoming gradually more

-ANIMAL.

and more numerous, and the nervous system
generally more and more complicated as we
rise in the scale of animal creation. The ner-
vous system is before long found to consist of
other parts than a series of similar ganglions
supplying at once the organs of sensation and
those of digestion; it has a central part super-
added, from which issue immediately the
nerves that supply the organs of the senses,—
sight, hearing, taste, and smell, which at the
same time make their appearance with their
especial capacities. This central superadded
portion is the brain, with its prolongation in
the vertebrata entitled spinal marrow. Nor in
the more perfect classes of the animal king-
dom is the nervous system even thus simple ;
among them it consists essentially of two
grand divisions, the one including the brain
and spinal cord and the nerves thence pro-
ceeding, the other constituted by the system of
the great sympathetic, or that series of ganglions
which, situated on either side of the vertebral
column, from the head to the pelvis, are con-
nected with one another, and with the cerebro-
spinal system, by branches of communication,
‘and furnish the digestive apparatus with almost
the whole of the numerous nerves it receives.

The nervous system in its relative degree of
development and complexity becomes the
ultimate standard by which the perfection of
animals is estimated, and their place in the
scale of creation assigned to them: if man
‘stand alone and unattended, as he undoubtedly
does, upon the summit of the pyramid, it is
‘only because he possesses in his brain the
organs of certain moral and intellectual facul-
ties which occur in no other living thing; these
confer on him his humanity; these are the ma-
terial parts to which the soul is wedded during
his existence.

In intimate connection with the functions of

hrenic or animal life, and developed nearly

in the same ratio, is the muscular system, the
most universal agent of locomotion. Exceed-
ingly simple at first, and operating at great
‘disadvantage through a want of levers and
points of support, we trace it becoming gra-
‘dually more complicated as we ascend, and,
finally, provided with a complementary skeleton
or frame-work by means of which it acts to the
best advantage. The skeleton among animals
is of two kinds,—external and horny, internal
and osseous. In the first case the muscular
system is inclosed within the resisting pieces
which it bas to move; in the second it is
without these, and is arranged around them.
‘The bones and muscles together compose the
numerous and variously fashioned instruments
with which animals accomplish the promptings
of their inward appetites and instincts. They
form feet, fins, hands, the prehensile tail, &c.
The muscular system, and a modification of
the osseous, the cartilaginous, moreover, com-
‘pose the most universal instrument by which
animals communicate their vicinity, their states,
their dispositions or affections, &c. to one ano-
ther—this is the larynz.

The means by which species are continued,
are extremely varied. e very lowest tribes

144

of animals we have seen shooting forth buds
exactly like vegetables, and these being in due
season detached from the body of the parent,
find themselves fitted to commence an inde-
pendent existence. At the next step we take
in ascent, however, we meet with particular
organs of reproduction; and, singular enough,
the moment these exist they are not of one,
but of two kinds, denominated male and fe-
male. Sometimes these organs are possessed
by single individuals, far more commonly,
however, they are divided between two, whence
the so uniform division of the beings com-
posing the animal kingdom into sexes. The
simplest form of the male organ of generation
is a gland secreting a fecundating fluid (the
testis) and an excretory duct: the simplest
form of the female apparatus of generation is
a gland or body producing germs (the ovary)
and an excretory duct. In a greater state of
complication or development these essential
parts in the male have an instrument super-
added to them by which the fecundating fluid
is carried directly into the body of the female,
and in the female the ovary has a dilatable
cavity superadded in which the germ remains
for a season, and until its included embryo
attains such a state of development as is com-
patible with its more independent existence
surrounded by the circumstances amid which
it is afterwards to live. In the higher classes,
the connection between the parent and offspring
does not cease immediately on the birth of
the latter, and in the highest of all we find
the female furnished with a complementary
apparatus (the mamme), from which she fur-
nishes her young with food during the first
period of its existence.

Actions of animals—The foregoing rapid
sketch of the grand features of distinction
among animals with reference to their struc-
ture naturally leads to the inference of di-
versity of function in harmony with the pecu-
liar organization possessed by each. In the
lowest grades of animal existence we have
seen to how simple a process the act of nutrition
—this act so complicated among the more
elevated tribes,—is reduced. It consists merely
of imbibition or absorption by and of exha-
lation from the general surface of the body.
The matters absorbed appear to be assimilated
incontinently, or to be made a part of, and to
receive the form proper to, the animal in the
instant of their assumption: applied imme-
diately to the homogeneous organism, the
nutriment is forthwith made a portion of its
substance. The vital decomposition of the
bodies of these lower animals is accomplished
with the same simplicity and directness: the
surface that absorbs is also that which exhales
the worn-out particles of the system.

The first step by which nutrition becomes
more complex, as we rise in’ the scale of cre-
ation, is the institution of a process of solution
(digestion), by which the matters appropriated
as aliment are prepared for reception into
the body. This process of solution is accom-
plished by powers inherent in the animal itself,
within a cavity destined for the purpose. In

142

our survey of the structure we have already
seen to how great an extent the organization
became complicated as a consequence of this
centralization of the office of digestion, and
with what variety of superadded function this
complication was attended, namely, external
absorption, sanguification or the formation of
a fluid, the pabulum of nutrition, confined
within vessels, respiration, circulation, and,
finally, assimilation, in regard to the compo-
sition; whilst with reference to the vital de-
compositions we have discovered another spe-
cies of interstitial or internal absorption, and
depuration of the system by one principal
apparatus, the kidney, to which the cutaneous
and pulmonary exhalations may be added as
supplementary.

But every one of these functions, and its
organic apparatus, are themselves modified,
according to internal aptitude, and in con-
formity with the circumstances surrounded by
which animals commence and continue their
existence. Digestion is a very simple process
in those cases in which it takes place within
a single cavity, having but one opening, and
no complementary apparatus of any kind,
compared with what it is when connected with
an apparatus for bruising the food, for mixing
it with saliva, for macerating it in a crop ora
series of reticulated and foliaceous pouches,
mixing it with bile, pancreatic juice, &c. &c.,
and transmitting it along a muscular canal,
of six, eight, or ten times the length of the
body to which it belongs.

Absorption, in like manner, among the most
inferior classes is essentially one and undi-
vided either in kind or destination. It is in
itself adequate to the entire office of nutrition,
seizing and transmitting the matters which are
fitted for this end, elaborating the food and
atmospheric air at the same instant of time,
and effecting immediately the composition of
the whole animal organism. In animals higher
in the scale, we perceive, in the first place, that
there are several species of absorption: there
is, in the first place, the absorption from the
surface of the digestive passages and that from
the surface of the lungs, gills, skin, &c. or of
the respiratory apparatus. Again, absorption is
not limited to furnishing materials for the com-
position of the organism; it is also entrusted
with the office of abstracting from its interior
the particles which are worn out and no longer
fit to continue the ends of their existence in
the places they occupy. Nor is this all; for
it is by absorption that the amount of those
exhaled fluids which moisten internal cavities,
having no external communications, is regu-
lated, and by which, as it would appear, many
of the secreted fluids, the bile, and the sper-
matic fluid in particular, are inspissated and
rendered more fit to accomplish the important
ends they subserve in the economy. Absorp-
tion in the highest classes of all is even per-
formed by two, and perhaps three different
orders of vessels, the lacteals, namely, the
lymphatics, and the veins.

Further, absorption is not in the higher as
it is in the lower classes of animals a function

ANIMAL.

effecting immediately the composition and de-
composition of the parts and particles of the
organization. It is intermediate to the pre-
paration of the nutritious juices and their ap-
ropriation or assimilation by the organism.
Amhe lacteals or absorbent vessels of the in-
testines collect the fluid called chyle from the
pultaceous alimentary mass in its progress
through the intestines. But this fluid is not
yet fitted to subserve nutrition; as a pre-
liminary it has to be subjected to the action
of the atmospheric air in the gills, lungs, &e.,
where, being converted into arterial blood, it
first becomes apt to minister to the growth
and reparation of the body and its parts. So
also in regard to decomposition: the fluids
collected from all parts by the lymphatics and
veins, are not immediately rejected from the
economy, as useless and having already accom-
plished all of which they are susceptible, but
being first exposed to the contact of the at-
mosphere, and then made to undergo the
scrutiny of the depurative organs, they are
either retained, being restored to their pristine
capacity to subserve nutrition, or are abstracted
from and thrown out of the body as no longer
fit to aid in its growth and maintenance.
Intercourse with the air of the atmosphere is
essential to every living thing, and we should @
priori have anticipated very considerable variety
in the means by which, as well as the mode in
which this intercourse is established. Among
the inferior tribes which are nourished by ab-
sorption immediately from the surface of their
body, and which find the materials of their
nutrition ready prepared for their use in the
circumambieut media, we may presume that
the matters absorbed have either undergone
the needful changes by exposure to the air
previously to their assumption, or that these
changes take place at the time they are ap-
propriated. Where digestion is a preliminary
to absorption and assimilation, it is evident
that this could not have been the case; and
hence the necessity for that modification of the
function of aeration entitled respiration. Look-
ing generally, we observe two principal varieties
in the mode by which aeration is accomplished :
in some classes there are a number of holes
arranged symmetrically along the sides, and
communicating with air-vessels entitled tra-
chee, which are subsequently distributed to
every part of the body. The air in this case
is evidently brought into communication with
the nutrient juices already arrived at their
destinations ; and the necessary changes are
wrought in them at the instant of their assimi-
lation. Here the respiration is very properly
said to be diffuse or disseminated. In other
classes, again, in which the respiration is local

or concentrated, in harmony with the existence

of a special apparatus, which we have spoken
of under the title of lung or gill, aeration is a

accomplished by the access of the air on the

one hand, and the exposure to its action of the _
nutritive fluid on the other, the effect of which
is to convert the latter into arterial blood, and —
to make it fit, upon its distribution by appro- —
priate channels, to accomplish the ultimate and —

ee aes ae ae

ANIMAL.

immediate nourishment of every part of the
organization.

The different media in which animals live
involves the supposition of another modifica-
tion as to the mode in which the blood or
nutritive fluid is aerated. Those that live in
air respire this elastic fluid immediately ; those
that live in water, again, respire it mingled
with or dissolved in the surrounding medium.
The trachee of those avimals whose respira-
tion is diffuse, and that exist on the surface
of the earth, consequently are filled with air;
those of the creatures that exist in water are
conduits for the constant transmission of this
fluid. When the respiration is concentrated,
corresponding modifications in the function
are encountered according to the medium in
which animals live: the air is either received
immediately into the body, when the apparatus
is known as a lung, or, suspended among
water, it is passed over the surface of the
pcr ges organ, which is then denominated
gill. Quadrupeds and birds respire univer-
sally by means of lungs, fishes and the mol-
lusca by means of gills. In certain reptiles
the function is carried on by means both of
lungs and gills, and as it would appear even
by the general surface of the body either vica-
riously, or at one and the same time. These
are the only true amphibious animals.

A circulation, properly so called, is the ap-
panage of an organization already somewhat
complicated, consequently of an animal con-
siderably raised in the scale of creation. This
function, it is evident, as implying in its sim-
plest sense a gy te motion of the general
nutritive fluid or blood, can only exist where
such a fluid is encountered. It is altogether
wanting, therefore, among those animals in
which nutrition is accomplished immediately.
We ascend but a little way in the scale before
we find the function consisting not only of an
outward or progressive motion of the nutritive
fluids, but of a retrograde motion also of these
same fluids modified in their nature, and re-
quiring exposure to a greater or less degree in
some form of respiratory apparatus to fit them
anew for distribution to the organization at
large. The fluid in this instance parts from
@ centre, and returns thither after having made
the round of the system. Circulation in this
acceptation only occurs among those animals
that have a separate respiratory apparatus, and
in which we meet with absorption of nutri-
ment from without, and of lymph, &c. from
within. The pabulum of nutrition is taken
up by lacteals and veins from the digestive
apparatus, and by veins and lymphatics from
the rest of the organism for transmission, under
the name of venous blood, to the apparatus of
respiration, whatever its form. In this the
fluid, still immature and unapt for assimilation,
is exposed in vessels of infinite minuteness
and extreme tenuity to the action of the at-
mospheric air, and having undergone in these
a certain change, it begins to be collected by
another set of vessels, which form branches suc-
cessively of larger and larger size, until finally
it is projected from the respiratory apparatus in

143

one or more trunks, under the name of arterial
blood, fitted for assimilation by the organization
at large, and proving the principal stimulus
under the influence of which its various par-
ticular organs accomplish their offices.

Circulation, however, as a function, is com-
plicated in the same degree as the apparatus
by which it is effected. In some classes we
find the circulation taking placing through
vessels only, one set distributing the blood from
the respiratory apparatus to the body generally,
another collecting this fluid again, and the
newly-absorhed matters from the body at large,
and transmitting these for elaboration anew in
the organ of respiration. In other tribes, and
this invariably after the very lowest grades of
the scale are passed, we find the hollow muscle,
or forcing apparatus, which, in glancing at the
differences of structure, we have spoken of
as the heart superadded to the circle of vessels,
which even in its simplest state consists of
at least two cavities communicating with one
another, one for the reception of the blood
from, the other for the projection of this fluid
to the general system.

But the blood does not follow the direct
and simple course here supposed in almost
any case. There is the aeration of the fluid
in the way, and means to accomplish this
important end must of course be provided.
Among many animals it would appear by
no means necessary that the whole of the
blood should undergo exposure in the respira-
tory apparatus, in order to fit it for the wants
of the organization ; a part only“is sent thither,
and this on admixture with the remainder
suffices to revivify the mass. In this case it
is not imperative that the two kinds of blood—
the unaerated or venous, and the aerated or
arterial—should be kept distinct; there is con-
sequently no occasion for more than one re-
cipient cavity or auricle, into which the aerated
blood from the organ of respiration, and the
unaerated blood of the system are poured in
common and mingled, and one projecting
cavity or ventricle from which the mixed cur-
rent is distributed partly to the respiratory ap-
paratus and partly to the system at large.
Here the blood in its course describes no more
than a single circle, beginning and ending in
the heart, which is then characterized as simple,
consisting, as has been said, of a single auricle
and a single ventricle. Among other tribes of
animals, however, the whole mass of blood
requires to undergo aeration in the respiratory
apparatus each time it completes its round
before it can again subserve the wants of the
organization. In this instance it is evident that
the aerated and unaerated blood require to be
most particularly prevented from commingling,
and that a single or simple heart will no longer
suffice as the implement of circulation. This
complex circulation is met with among ani-
mals so low in the scale as to be unprovided
with a heart, when of course it is accomplished
by means of vessels only. In some tribes the
one portion of the function is performed by the
medium of vessels, the other by the agency of
a heart which is now connected with the gene-

dd

ral systemic circulation, now with the pul-
monic, being situated in the one case in the
course of the aerated, in the other in that of
the unaerated current of blood. In the most
elevated classes of animals, finally, the double
circulation is effected by means of ¢wo hearts,
one dedicated to the projection of the un-
aerated blood into the lungs, the other to the
propulsion of the aerated fluid through the
general system. ‘These two hearts, indeed,
adhere to one another, and are usually spoken
of as if they constituted no more than a single
organ, having however four cavities, two
auricles and two ventricles, but they are
not less distinct on that account, and are
severally the centre of a particular circula-
tory system, one of which commencing in the
cavities for the venous or unaerated blood, ex-
tends through the respiratory apparatus (then
uniformly a lung), and back to the cavities for
the arterial aerated blood; the other, com-
mencing in the cavities just named, extends to
every part of the organization, and terminates
in the cavities for the unaerated blood, where
the lesser round recommences, to be followed
in its turn by the greater, and so on, during
the whole period of existence.

Assimilation appears to be identical in all
. animals; it is the ultimate term of nutrition,
and however varied the apparatus that minis-
ters to the act, the act itself we may presume
not to differ in its essence in one animal from
what it is in another.

Akin to assimilation we have secretion, and
this is a function that offers extensive differences
in every class of the animal kingdom. It is
generally spoken of as of two kinds, excretion,
and secretion, properly so called. In the lowest
tribes excretion is quite simple, consisting of a
mere exhalation from the general surface of the
body. In the more elevated we find another
and very important form of excretion super-
added, that, namely, of the urine, the nature of
which, and the mode in which it takes place,
we have already indicated in speaking of the
structure. Secretion, however, even in the
classes but a little raised above the lowest, is a
function of much more varied import, and con-
sists of a great many other processes than that
by which the bodies of animals are depurated
and their blood maintained in a state fit to
supply ail the wants of the system. We ad-
vance buta little way before we begin to detect
distinct organs destined for the secretion of
peculiar fluids from the general mass of cir-
culating nutriment, evidently subservient in
many cases to the most important ends of the
economy, and by no means destined to be
rejected from the system as useless, like the
excretions properly so called. It seems even
that it is by a process analogous to secretion
that the imponderable matters—the heat, light,
and electricity, which we have acknowledged
as elements in the constitution of organized
beings, are eliminated. .

All animals possess sensibility or sensation,
though evidently in the most dissimilar degrees.
_ Some have been supposed to possess the faculty
_.of perceiving impressions made upon them by

ANIMAL.

-which man alone, of all created things, poss

external objects, but to have no power of vre-_
acting upon external nature, they being without
the faculties which in the higher classes prompt
to action. This state, however, of animal ex-—
istence is rather hypothetical than demonstrable,
and in animals generally we observe not only the
aptitude to be impressed, but inherent capacities
inducing reaction upon the world around them.
The sensitive life of these beings consequently
consists of two items—the senses and their
organs, external and internal, by which im-
pressions are received and cognized, and the
affective and intellectual faculties by which the
motives to action, the propensities, sentiments,
instincts, appetites, &c., are originated, and
the means and modes of accomplishing their
promptings are supplied.

Animals evidently differ immensely in the
degrees in which they are endowed with ex-
ternal and internal senses. Some appear to
possess none of the external senses save touch ;
others, in addition to this, have taste and smell ;
the most perfect besides these three reckon
sight and hearing. The internal senses, in like
manner, are more or less acute, more or less
numerous, according to the consitution of ani-
mals: those of hunger and thirst are probably
universally distributed, and the most keenly
felt; then come those which induce the respira-.
tory act, the sexual act, &c.; and here we
find ourselves among the propensities which
exist in very different numbers and kinds in
every different species of animal. Some tribes
tend their offspring, others leave their progeny
to the care of accident, which in this case
always suffices for their protection ; some con-
gregate in herds or shoals, others live solitary
or in pairs; some are bold and rapacious,
others timid and gentle, &c. When we ex-
amine animals generally, with reference to the
sentiments or moral faculties, we find them
still more or less like each other in many
respects, some being cautious or cowardly,
proud or haughty, persevering or obstinate, &c.,
in various proportions. When we contrast all
other animals with man, however, in regard to
moral endowment, we immediately perceive
the broad, the impassable line of difference that
runs between the lord of creation and all the
other beings that with him partake of life. The
feeling which leads man to view his actions in
their bearing upon others or in relation to jus-
tice, is extremely weak among animals, if in-
deed it do actually exist among them at all.
The same may be said of the sentiment which
leads mankind to wish well to all, and to
succour and relieve those that are suffering and
unfortunate. The feeling, again, that raises”
man to the imagination of a something beyond
nature, the sentiment that inclines him to reve-
rence and adore his Maker, thus in one way re-—
vealed to him, and the wonderful impulse
leads him to look beyond time and his me
temporary existence, and thence to conceiv
finity and eternity, are so many moral attri

:

Similar diversities in intellectual e
are apparent when we survey the ani
dom at large. Intelligence appears u

ANIMAL.

wanting in numerous and extensive classes, and
it varies conspicuously in the members of every
tribe among which it is apparent. In his in-
tellectual powers man is not less eminently
raised above all the other beings of creation
than in his moral constitution: he alone takes
note of the phenomena that pass around him
with ulterior views, and he alone perceives the
‘ relation between effect and cause, preparing
and foreseeing consequences long before they

a

comotion is a function so evidently in re-
lation with the circumstances surrounded by
which animals exist, and with the apparatus by
which it is accomplished, that it is enough to
refer back to the structure for proof and illustra-
tion of its infinite modifications among the
various genera and species of the animal king-
dom. Some, by their constitution, are inca-
pable of motion from place to place, but they
still perform those partial motions which their
preservation as individuals require—taking their
food, respiring, voiding their excretions, &c.

Those that can move from one place to another

have organs in relation to the mode in which

this motion is accomplished, whether it be by
creeping, by swimming, by running, leaping,
flying, &c. &e. Every partial movement ex-
ecuted by the higher animals has, farther, its
own special apparatus: the intestinal canal has
its muscular parietes; the necessity that is felt
to communicate internal sensations and ideas
has its pathognomonic means in the looks,
- gestures, sounds of the voice, and so on.

Nor is it only in the greater or less degree of
complexity of their general structure, in the num-
ber and diversity of their particular organs, or in
those of the actions whose sum constitutes their
vitality, that animals differ from one another; they
vary farther in the degree in which these organs
and these functions are enchained or mutually
dependent. In the most simple animals so
_ complete is the independence of the several
_ parts, that their bodies may be divided into
_ humerous pieces without injury to the vitality
_ of any one of them, each possessing in itself
_ the capacity to commence a separate existence.
_ TInammals somewhat more elevated in the scale
_ we observe very extensive powers of reproduc-
_ tion at least, of parts that have been lost, and even
of continuing existence in very insignificant
_ remainders of their bodies. In the most ele-
_ vated tribes, however, the dependence of every
part upon the whole becomes such that neither
____will the body essentially mutilated survive, nor
____ will any part of the slightest consequence con-

_ tinue to live. Among the beings at the bottom
of the scale we have in fact found the organiza-
____ tion to be homogeneous, or without distinction

___ of parts, and nutrition to be accomplished by
__ means of an immediate absorption and exhala-
_ tion; and as every part possesses the structure
__ which makes it capable of these two acts, every
: Ee ae it is evident, suffices for its own existence.
___ In the higher classes of animal existence, how-
sever, nutrition requires the concurrence of a mul-
____ titude of peculiar acts; and in order that life may
| be continued in any fragment of one of the mem-

__ bers of these, it is plain that this fragment must
VOL. I.

145

contain the organs of every one of the functions
essential to nutrition. Further, it is certain that
the nervous system, when once it has fairly made
its appearance, strictly dominates the nutritive
function, and that every part of the nervous
system itself becomes progressively more and
more dependent on one of its portions, the
encephalon or brain, as animals stand higher in
the scale of creation, and as the functions over
which the nervous parts preside respectively
are themselves of a higher order. These are
new and additional reasons for the centraliza-
tion of life, or for the complete dependence of
the organs and their functions one upon another
among the more perfect animals—man, the
quadrumans and quadrupeds, birds, &c.

So much for the acts that minister to the
preservation of the individual. Let us now turn
to the interesting series by which species are
continued. In the very lowest grades this end
is accomplished without the concurrence of
sexes: at a determinate period of its life the
animal either separates into several fragments,
which become so many new and independent
individuals, or it throws out a number of buds
or germs from its external surface or from a
particular internal cavity. The first of these
modes of reproduction is entitled fissiparous,
the second external gemmiparous, and the third
internal gemmiparous.

When we examine animals in the next grade,
we find reproduction taking place by the con-
currence of sexes, or rather of two kinds of
organs which we afterwards discover divided
between different individuals, who are then
said to be of opposite seves. When the male
and female organs are united in the same indi-
vidual it is denominated an hermaphrodite ani-
mal, and in some cases seems to suffice for its
own impregnation ; more generally, however,
hermaphrodite animals are not capable of per-
forming this act upon themselves, but require
the concurrence of another individual of similar
constitution: the two hermaphrodites meet and
severally impregnate one another.

Among the more perfect classes of the ani-
mal kingdom the organs of reproduction are
universally allotted to two different individuals,
males and females, which consequently become
in their dualism representatives of their species.
Agreeing in this single feature, the modifica-
tions in the process of reproduction are never-
theless extremely numerous. In some cases
the fecundating fluid of the male is only ap-
plied to the egg or germ of the female after its
extrusion from her body, as happens among
fishes, several reptiles, &c.; in others the male
fluid is injected into the body of the female,
and made to fecundate the germ still attached
to its parent. This act is generally, though not
invariably, accomplished by means of a pents,
or male external organ, with which many birds
and all the animals above them in the scale of
animal creation are then provided.

With this contact or intermixture of bodies
we have the following varieties in the after-parts
of the process: the egg or germ now fecun-
dated is either forthwith expelled from the
body, and it is only subsequently, under the in-

L

146

fluence of a certain temperature, and after the
lapse of a certain time, that the young being
bursts the shell and commences its independent
existence; this is the case among oviparous
animals. Or otherwise: the fecundated egg
makes its way so slowly through the passages
that lead from the ovary outwards, that it is
hatched before it can escape, so that the young
one passes from the body of the mother imme-
diately. Animals in whom this happens are
justly said to be ovo-viviparous. In the third
and last place, the fecundated ovum is imme-
diately loosened from the ovary, but instead of
being laid, or extruded from the body immedi-
ately, it only passes along a canal to a certain
distance from the ovary, where it meets with a
reservoir or cavity (the uterus) to which it at-
taches itself, and within which it commences
a series of evolutions, at the expense of the
mother, preliminary to its final expulsion with
instincts ready formed, and an organization so
perfect as enables it to begin its separate ex-
istence. The classes in which this mode of
reproduction obtains, and they are the highest
of all, including quadrupeds and man, are en-
titled viviparous, so that in these, besides the
connection of the sexes and the fecundation of
the germ, we have the phenomena of utero-
gestation and labour.

And here the proper work of reproduction
ends; but the young are so generally born in
some sort immature, that in the higher classes
the connection between the offspring and pa-
rent does not cease immediately. In the class
of mammalia, indeed, the connection is little
less intimate during the earlier periods of extra
uterine life than it was during the whole term
of intra-uterine existence ; the young being
still depends upon its mother for the whole of
its nourishment, and very generally for the
supply of warmth it requires and the protection
needful to it till able to provide for itself.

Many of the particulars now merely glanced
at, and numerous others, the mention of which
has been omitted entirely, will be found de-
tailed, and their bearing and importance illus-
trated in the article on GENERATION, to which
the reader is therefore referred.

BIBLIOGRAPHY.—Stahl, De diversitate corporis
mixti et vivi, 4to, Hale, 1707. Berzelius, in
Afhandlingen i Fisik, Kemi, &c. (on the means of
ascertaining the definite and simple proportions in
which the component elements of organic bodies
are combined), t. iii. Stockh. 1810, and in Thom-
son’s Annals of Philosophy, vols. iv. and v.; Ejus,
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x. (R. Willis.)

_ ANKLE, REGION OF THE, (surgical
_ anatomy), (region tibio-tarsienne, Velp.) The
_ relative positions and other particulars con-
nected with the parts found in the region of the
ankle, owing to the numerous accidents which
cour here, are matters of great interest to the
rgeon. The extent and boundaries of this re-
on are by no means so distinctly defined as
ose of many others ; hence, in isolating it for
ecial description, the surgical anatomist is
: ee iged to assign to it arbitrary or imaginary
__ limits. We propose to adopt the following
', __ boundaries for this region, viz. superiorly a hori-
zontal line drawn round the leg two inches above

+ 3 .

SSA i oda Aa liga PIT Waser ol ihe lial

ie,

hl Ma dpa i ~A

1.

+

ee
ris

REGION OF THE ANKLE.

147

the malleoli, and inferiorly a line drawn across
the dorsum and sides of the foot at the same
distance from those bony prominences. In this
space are comprised the ankle-joint and several
important vessels, tendons, and other soft parts
well worthy of attention.

In examining the external characters of this
region we notice four well-marked sb este
one on either side, termed malleolus, (internus
v. externus); a third posteriorly, which cor-
responds to the tendo Achillis; and a fourth in
front, resulting from the projection of the astra-
galus. The malleoli do not accurately corres-
pond either in situation or shape to each other:
the internal lies upon a plane superior and
anterior to the external, and in a well formed
person is much less sharp and prominent,—
a fact, the recollection of which is of great im-
portance in estimating deformity or dislocation
of the joint. The cylindrical prominence be-
hind, as it depends upon the tendo Achillis,
will of course vary in size and tension accord-
ing to the relaxation or contraction of the
gastrocnemii muscles. Upon either side of
the tendo Achillis, between it and the malleo-
lus we meet with a deep groove, called by
some the calceo-malleolar furrow: that upon
the outside is extremely well marked, and we
may here distinctly feel through the integu-
ments two of the peronei tendons: the internal
calceo-malleolar groove is broader and shal-
lower, but of much greater interest, for through
it, in addition to certain tendons, we have
transmitted the principalvessels and nerves des-
tined for the sole of the foot. The anterior
prominence, named in popular language, “ the
instep,” is rounded in the transverse direction,
and in some individuals projects much more
than in others. On throwing the foot and toes
into action, as in walking, we can here dis-
tinctly recognize the tendons of the tibialis
anticus, extensor pollicis, extensor digitorum
longus, and peroneus tertius, and almost in
the mesial line may be felt pulsating distinctly
the anterior tibial artery.

Having thus examined the landmarks which
are to guide us in our anatomical investigation
of this region, we may next proceed to inquire
into the nature and relations of its constituent
parts. Besides the bones, cartilages, and liga-
ments which immediately constitute the joimt,
and form the basis of the region, we have like-
wise several other structures entering into its
formation; integuments, muscles, vessels,
nerves, and fasciz are here arranged in suc-
cessive layers beneath each other. We shall
accordingly describe four layers,— namely,
1. the skin; 2. the subcutaneous cellular
tissue; 3. the fascie; and 4. the tendons,
vessels, and nerves, which lie in immediate
contact with the articulation. Sr

1. The skin forms a complete investment
for the whole region, but its structure and
properties differ considerably in different situ-
ations. Upon the inner ankle it is smooth and
thin, and possessed of but little extensibility ;
so that in operating here, if we look forward
to union by the first intention, it becomes a
matter of great moment to preserve as much

L 2

148 REGION OF
of the skin as possible. Owing to the same
peculiarities of the integuments in this situ-
ation, no less perhaps than to the frequent
motion of the part, wounds and ulcers occur-
ring upon the inner ankle are extremely tedious
and troublesome, in many instances laying
bare the bone, and finally even occasioning its
destruction. Upon the outer ankle, the skin
is more pliant and extensible; hence the greater
facility of healing wounds and ulcers in this
part; and hence, too, the more frequent oceur-
rence of abscess and extravasation beneath the
surface. At the posterior part of the region
the skin acquires great strength and thickness,
becoming as it passes downwards still more
dense and unyielding, approximating in fact
to the character of the plantar integument.
Upon the instep it is also of tolerable thick-
ness, particularly in those individuals whose
feet are usually uncovered. In this situation,
however, it is soft and extensible: its natural
pliancy being still further increased by the
secretion of numerous sebaceous follicles
thickly scattered throughout its substance. It
is here, owing to the frequent motions of the
joint, thrown into transverse ruge, and hence,
in making an incision, to give exit to matter,
it may be proper to prefer a transverse toa
vertical direction.

2. Lhe subcutaneous cellular tissue.-—The
structure and properties of the subcutaneous
cellular tissue are not the same throughout the
whole region, but like the skin, which we
have just considered, its characters vary in dif-
ferent situations. ‘Thus, upon the instep, it is
at the upper part loose and distensible, full of
adipose cells, and similar in every respect to
the subcutaneous tissue of the leg, of which it
is a prolongation: as it descends, however, it
becdmes more dense and unyielding, and ad-
heres more closely to the skin which covers,
and to the annular ligament which is placed
beneath it. This anatomical fact at once ex-
plains why it is that when subcutaneous ab-
scess or infiltration occurs on the anterior part
of the leg or foot, the passage of the fluid
either upwards or downwards is, for a time at
least, impeded at the ankle-joint. It is like-
wise owing to the density of the subcutaneous
tissue across the ankle, that its cells do not
permit the accumulation of adipose substance
here; hence in very fat persons and also in
children whose subcutaneous fat is usually
abundant upon the leg and foot, the instep is
as it were strangulated by a deep transverse
furrow. Upon the malleoli the characters of
the subcutaneous tissue present great differ-
ences: upon the inner one it is scanty and
delicate, but of a compact structure, and con-
tains few if any adipose cells. Upon the outer
one it is, on the contrary, much more copious,
of a loose and yielding texture, and usuall
contains a greater quantity of fat. These dif-
ferences of texture will explain why, after
severe contusion, extravasations so frequently
occur upon the outer part of the joint and
so seldom upon the inner; why abscess is so
much oftener met with in the one situation
than in the other; and why the transmission

THE ANKLE.

of pus and serum from any of the neighbour-
ing regions takes place so much more easily —
about the outer than about the inner ankle. —
At the posterior part of the region, the sub-_
cutaneous tissue assumes again new characters: —
losing here its soft lamellated texture it be- .
comes suddenly dense and filamentous, ad-
hering with great firmness to the integuments
above, and to the fascia beneath: as we trace
it down it becomes more dense and elastic ;
the cells formed by the decussation of its
filaments become loaded with a firm granular
fat; in a word, it already begins to put on the
characters of the dense fibro-adipose cushion, —__
which is found in the sole of the foot. Hence
it is that wounds and abscesses of the part we -
are now considering, approach in character
those of the plantar region: hence the slight
swelling, the severe pain ; hence in both cases
the necessity of a prompt and free evacuation
of the matter.

Before leaving this subject we should ob-
serve that the subcutaneous tissue of the region
we are now considering transmits certain ves-
sels and nerves. In front of the inner ankle
we meet with the incipient branches of the
great saphena vein and the ultimate filaments
of the saphenus nerve: the venous branches
are here of such a size that they have fre-
quently been selected by the phlebotomist as
the seat of operation. Anteriorly we find the
filaments of the musculo-cutaneous nerve, and
externally the roots of the lesser saphena vein,
and its accompanying nervous filaments.

3. The fascia or aponeurosis forms the next
stratum we have to examine: it is placed be-—
tween the subcutaneous tissue and the tendons. .
The fascia, like the two preceding layers, forms |
a general investment for the whole region.
Its structure and properties, like those of the
preceding layers, vary considerably, according
to the situation in which we view it. Upon
the instep it becomes continuous, above with
the aponeurosis of the leg, and inferiorly
with the dorsal aponeurosis of the foot, but, —
for very obvious reasons, surpassing both of
these in strength. This additional strength is
owing to the accessory band of fibres which
passes transversely across the instep, interlaced
with the proper oblique fibres of the fascia,
and to which is given the name of anterior —
annular ligament. Arising from the anterior —
edge of the inner ankle this annular ligament ~
passes outwards and soon meets with the ten- —
don of the tibialis anticus: at this point it —
splits into two layers; the one passes before, —
the other behind the tendon, and they unite —
again at its outer edge. The same mechanism
is repeated in the case of the extensor pollicis”
tendon which lies immediately external to the
last-named tendon; and lastly in those of the
extensor digitorum longus and peroneus tertius.
In contemplating the mechanism and uses of
this ligament, the surgical anatomist cannot
but perceive that certain inconveniences
result from its division: its use beiug obvi
to bind down the tendons in this situation, and
to form canals for their free and se] trans-
mission, it is clear that after its division in the

i

RKEGION OF

living subject, when the individual attempts to

flex the foot or extend the toes, these tendons
will not only form an unseemly projection
upon the instep, but also the accuracy and per-
fection of these motions will be much im-
paired. Upon the lateral parts of the region,
the fascia is so intimately united to the peri-
osteum, that it is almost impossible to separate
them from each other, and hence some have
denied its existence here. Behind both mal-
leoli, it becomes however again very distinct,
forming in both situations a band similar to
that which we have just seen upon the instep.
The internal annular ligament arising from
the posterior edge of the inner malleolus
passes backwards to the os calcis; it is
thrown like a bridge across that deep gutter
which divides the heel and ankle from each
other, and it is destined like the anterior liga-
ment to form a covering to the tendons and
other parts which pass through this regjon.
Like the anterior, the internal ligament also
consists of two layers closely united to each
other. To express more distinctly the me-
chanical disposition of these layers, we may
say that the bridge formed by the internal

annular ligament consists of two arches ;

through the anterior arch are transmitted the
tibialis posticus and the flexor digitorum
longus tendons, wrapped each in its own
synovial theca: the posterior arch is occupied
with the posterior tibial vessels and nerves,
and the tendon of the flexor longus pollicis
muscle. Having thus safely conducted these
important organs, the superficial layer of the
ligament fixes itself into the os calcis, while
the deep one passes backwards and upwards
to become continuous with the deep fascia of
the leg. Behind the external malleolus, the
fascia forms another but less remarkable liga-
ment, which Blandin calls the “ external an-
nular:” this passes from the fibula to the
astragalus, and forms with the posterior edge
of the malleolus a deep osseo-fibrous canal for
the transmission of the peroneus longus and

brevis tendons.

At the back part of this region, the fascia is
also found covering the great tendo Achillis ;
this tendon also, like the smaller ones we have
just spoken of, is not merely covered super-
ficially, but is contained within a sheath,
formed by the splitting of the fascia into two
layers : the posterior layer we may regard as
the Beatie fascia itself; the deep one passes
in front of the tendon, and if we trace this up-
wards, we shall find it becoming ultimately

continuous with the deep fascia of the leg. An

acquaintance with the disposition and structure
of the fascia we have thus described, will en-
able the surgical anatomist, in almost every in-
‘stance, to explain the time, situation, and pro-
gress of abscesses occurring in this region: he
will at once comprehend that three distinct
sorts of abscess may form here :—one in the

subcutaneous tissue, and which being super-

ficial to the fascia can hardly penetrate deeply

toward the joint; another, occurring between

the two layers of that membrane, in those

‘situations where it splits to include the ten-

THE ANKLE. 149

dons ; such an abscess will have little tendency
to point in front, being bound down by the
superficial layer of the fascia, or to penetrate
deeply for a similar reason; but to its free
passage upwards or downwards in the course
of the tendons, little or no obstacle is presented.
Lastly, matter may accumulate under hoth
layers of the fascia, where its deep position and
close confinement render it alike dangerous, and
of difficult detection.

4. The next stratum is perhaps less entitled
to that name than those we have hitherto
described. Instead cf forming, like them, a
general investment for the whole region, it
consists of several distinct and independent or-
gans scattered irregularly about the joint: we
shall enumerate them in the order in which we
propose to treat of them, viz., tendons, mus-
cles, arteries, veins, lymphatics, and nerves.

a. Lendons. Upon the instep we find no
fewer than seven tendons passing towards the
foot: the internal is the largest of all, it is that
of the tibialis anticus running obliquely for-
wards and inwards to the inner cuneiform bone.
Close upon its outer side is the tendon of the
extensor pollicis; still more outwards we meet
with the four tendons of the extensor digitorum
longus, and most externally of all, or nearest
to the outer ankle, that of the peroneus tertius.
We need not revert to the subject of the fibrous
sheaths furnished to these tendons by the fascia
or annular ligament; but we should here care-
fully observe, that both sheaths and tendons are
completely lined by asynovial apparatus. He
who is at all acquainted with the general patho-
logy of synovial membrane will understand why
it is that effusions so frequently form about the
instep ; why adhesion of the opposite walls of
these synovial sheaths will almost destroy the
power of extending the toes and of flexing the
foot ; and, lastly, he cannot but draw the im-
portant practical deduction, that in operations
about the instep we should avoid, if possible,
cutting into these synovial sacs.

Behind the inner malleolus we meet with
three tendons, — that of the tibialis posticus
most anterior, and in close connexion with the
posterior surface of the malleolus internus; that
of the flexor digitorum longus a little further
back ; and still more posterior, and at a little
distance from the others, the tendon of the
flexor pollicis longus. These are included, as
we have already explained, in fibrous sheaths
formed by the internal annular ligament, each
sheath and tendon having its own synovial
lining. We may here observe a good anatomical
reason, why inflammation affecting the sheath
of the flexor digitorum will, ceteris paribus,
be more likely to prove dangerous than that of
the tibialis posticus: for, as the synovial sheaths
of the former extend along the whole sole of the
foot, little or no obstacle is presented to the
disease extending itself into that region : whereas
the tendon of the tibialis being inserted, not
upon the sole, but rather upon the inner edge
of the foot, its synovial membrane forms here
a cul-de-sac, no doubt presenting some obsta-
cle to the inflammation extending beyond this
pot. Behind the outer malleolus there exists

150

a deep groove, in which two important tendons
are contained, those, namely, of the peroneus
longus and brevis. They are lodged in a canal
which we have already described as formed by
the bone and the external annular ligament,
and this canal is lined by a distinct synovial
membrane reflected upon it from the tendons.
Having passed over the ligaments of the outer
ankle, the peronei tendons are next applied
upon the surface of the os calcis; and here,
though previously in close apposition, and in-
deed contained within the same synovial sheath,
they become separated by a ridge projecting
from the bone. The peroneus longus tendon plays
behind it as upon a pulley, and instances have
occurred, where, owing to the fracture of this
little osseous septum, the peroneus longus has
been dislocated forwards upon that of the
brevis. It hasalso happened that both peronei
tendons have been dislocated forwards from
their groove behind the malleolus, and thrown
in front of that eminence. Were such an acci-
dent left without surgical interference, it is inte-
resting to reflect how completely altered would
be the action of these two muscles, if that action
were not completely suspended by the inflam-
mation and obliteration of the synovial sheath
consequent on the accident ; instead of extend-
ing the foot and pointing the toe, as they do in
their natural state, they would become con-
verted into flexors and abductors of the foot.
At the posterior part of the region, the tendo
Achillis forms a remarkable projection. In our
account of the fascia, we have described the
sheath within which this tendon is contained.
We may further observe that this tendon is
separated from the joint, and also from the
deep vessels and nerves of the leg, by a consi-
derable interval, so that it has frequently been
cut across without injury to the articulation *or
wound of any other important part. Its mode
of insertion into the os calcis is also worthy
attention ; instead of being fixed into the whole
posterior surface of that bone, it occupies by
its insertion merely the lower half of it ; supe-
riorly the bone and tendon are not even in con-
tact, for here a distinct synovial bursa is inter-
posed between them. The liability of this
large bursa to inflammation and effusion should
be carefully borne in mind by the surgeon : and
he who is aware of its office, placed as a friction
roller between the tendon and bone, will duly
estimate how much disease of this bursa will
impede the motions of progression. Owing to
the interposition of the bursa, rupture of the
tendo Achillis has occurred even below the
upper edge of the os calcis ; and if, having cut
across the tendon, we forcibly extend the foot
so as to elevate the heel, we shall at once com-
prehend how indispensably necessary it is to
maintain the extended position in our treatment
of this important accident.

b. Muscles. —There are but few muscular fibres
met with in the region of the ankle: the flexor
digitorum brevis arises upon the instep; and
posteriorly we find some of the fibres of the
flexor pollicis longus, which are here continued
down a considerable way upon the tendon.

_ c. Arteries.—The arteries about the ankle,

REGION OF THE ANKLE.

of great interest. Upon the instep the course

and relations of the anterior tibial artery de-

mand particular attention; the vessel here

does not run exactly in the median line of the

foot, but is somewhat nearer to the inner than .

to the outer malleolus: we may always reach 4
d
(

from their liability to injury and disease, become :
q

it with perfect certainty, by cutting between the
tendon of the extensor digitorum longus, and
that of the extensor pollicis ; these overlap it
upon either side, and afford considerable protec-
tion against wounds or other injuries. Not-
withstanding the facility of reaching the vessel
in this situation, it is by no means advisable to
do so when it is at all possible to avoid it, inas-
much as to expose the artery here it is necessary
to wound the synovial sheaths, and inflammation -
and adhesionwould be the probable consequence
of such an injury. The branches of the in- :
ternal malleolar artery are found upon the
inner part of the region, running upon and in
front of the inner ankle, and anastomosing with
others passing forwards from the posterior
tibial, thus insuring a sufficient supply of blood
to the joint, even when the trunk of the anterior
tibial itself has been tied. But these vessels
are of much inferior importance compared with
the posterior tibial, whose main trunk lies in
the fossa between the heel and the malleolus
internus. It is here occasionally the subject of
operation, and hence its course and relations
should be very carefully noted. We have al-
ready enumerated the tendons passing beneath ;
the annular ligament in this situation ; the most :
anterior is that of the tibialis posticus, imme- |
diately behind it lies that of the flexor digi-
torum, and still more posteriorly, at the interval
of about an inch, is found the tendon of the
flexor pollicis ; in this interval between the twe
latter tendons runs the posterior tibial artery,
not however equidistant from both, but nearer
to that of the flexor digitorum; it rests upon
the tibia and internal tibio-tarsal ligament, and
is covered by the integuments and annular
ligament; its vene comites run one upon
either side ; and the posterior tibial nerve lies
close behind it, but as the vessel descends get-
ting gradually to its inner side. Notwith-
standing the few coverings of the artery in this
situation, yet owing to the heel, the ankle, and
the tendo Achillis projecting around, and hearing
off as it were those coverings from it, the vessel
is here at a considerable depth from the surface ;
and any one who supposes it can be easily found
in the living subject, will form a very erroneous
idea of its true position :—hence it is that all
good writers on surgical anatomy recommend _
us to take up the artery in the lower third of —
the leg, rather than in the calceo-malleolar
groove. Several small vessels ramify about
the outer ankle, the external malleolar coming _
from before meets here with the terminating —
branches of the peroneal artery from behind, but —
these small vessels are interesting to the sur-_
gical pathologist rather than to the regional
anatomist or operative surgeon. an
d. Veins.—Two veins, the “venz comites,” —
accompany each of the larger arteries: in all —
operations upon the artery, the close apposition —

i

a) *

x
-
5
%
o
+.
+
4
M
4
»

JOINT OF THE ANKLE.

of the veins, and the possibility of mistaking
one for the other, should be remembered by
the surgeon. In front of the inner malleolus
we observe one or two openings in the fascia,
through which small branches of communication
pass between the superficial and deep veins;
these, no doubt, are the principal channels
through which the venous blood of the integu-
ments about the foot and instep is returned,
after the operation of tying the great saphena
vein.

e. Lymphatics.—The lymphatics consist like-
wise of two sets; the one lying beneath the
integuments and scattered irregularly over the
region; the other lying beneath the fascia, and
for the most part accompanying the blood-
vessels. Some anatomists speak of a lymphatic
gland lying upon the instep, and receiving
several of these deep absorbents; in the majo-
rity of cases there is no such gland, and its
existence in any appears to us extremel
doubtful. ° Op kt

f. Nerves—The nerves in this region have
the same general distribution as the arteries.
In our account of the larger arteries, we have
already minutely assigned the relation which
their accompanying nerves bear to them. We
may thus briefly enumerate them :—in front,
the musculo-cutaneous and anterior tibial; on
the inner side the terminal ramifications of the
internal saphenus and the posterior tibial ; and
on the outside, the terminal branches of the
external saphenus. For further particulars re-
specting the nerves, we refer to the articles

uMBAR Nerves; Sacrat NeErvES.

For the BIBLIOGRAPHY of this article and all

others on surgical anatomy, see the Bibliography
of ANATOMY (INTRODUCTION. )

(John E. Brenan.)

ANKLE, JOINT OF THE.—(Normal ana-
tomy.) (Fr. articulation du coude-pied. Germ.
Fussgelenk. (tal. caviglia.) The ankle-joint, or
tibio-tarsal articulation, results from the junc-
tion of the leg and foot. For reasons which

will appear when we come to explain its mo-

tions, it is ranked in the excellent and com-
prehensive classifications of Bichat and Cloquet
as a perfect angular ginglymus. The security
of the ankle-joint, more perhaps than of any
other in the body, is owing to the peculiar
form of its bones, and to their exact adap-
tation to each other; in this respect it has
aptly been compared to the tenon and mortise
joint, so frequently used by mechanics, the
strength of which, as is well known, is chiefly
Owing to the peculiar form and close fitting of
its component parts. Upon the upper part of
the foot, we meet with, it is said, a true and well
defined tenon, and upon the lower part of the
leg a tolerably perfect mortise for the reception
of the tenon. The comparison, though perhaps
not strictly correct, will however assist us in
understanding how much the security of this
joint depends upon the form and fitting of its
bones ; and will explain to the beginner why,
in: treating of the ankle-joint in particular with
a view to demonstrate its use and mechanism,
a brief account of its bones becomes part of our

151

description no less essential than of its liga-
ments themselves. In our account, therefore,
of this articulation, we shall, in the first place,
describe its bones; next its ligaments; and,
lastly, shall offer some remarks upon its me-
chanism and uses.

a. The Bones.—Three bones contribute to
the formation of the ankle-joint; the tibia and
fibula form, by the union of their inferior por-
tions, a deep depression, into which the head of
the astragalus is received. The ¢ibza, as it ap-
proaches the joint, looses gradually its prismatic
shape, and assumes a well-defined cubical or
quadrangular form. On its lower extremity it
presents a quadrilateral articulating cavity,
covered in the recent state with cartilage ; this
cavity is transversed from before backwards by
an obtuse ridge which subdivides it into two
smaller cavities. Of the four sides or margins
of this articulating cavity, the anterior is almost
straight transversely, but convex or rounded off
in the vertical direction, with the obvious design
of permitting a greater flexion to the foot; the
anterior tibio-tarsal ligament arises from this
margin. The posterior margin is also straight
transversely, but vertically convex, to permit an
increased extension to the foot; the posterior
tibio-fibular ligament is connected here: a
shallow oblique groove is met with upon the
outer part of this surface, for the transmission
of the flexor longus pollicis tendon. The ex-
ternal side presents a depression for the reception
of the fibula; this articulating portion is pro-
longed upwards for nearly an inch, is of a
triangular form with the base below ; the sides
of the triangle give attachment to the anterior
and posterior tibio-fibular ligaments; and the
area of the triangle is rendered rough, except at
its lowest part, by the attachment of the inferior
interosseous ligament,—another strong bond of
union between these bones. The inner edge is
prolonged downwards nearly an inch in length,
forming the prominence known by the name of
malleolus internus; this is placed upon a plane
superior and anterior to the malleolus externus;
it is somewhat flattened in shape, and has one
surface looking inwards or towards the mesial
line ; this in the living subject is covered only
by the integuments; the outer surface enters
into the formation of the joint, hence it is
tipped with cartilage to permit the astragalus to
play upon it; the anterior edge is sharp and
gives origin to the anterior tibio-tarsal ligament;
the posterior edge is traversed by a broad and
generally well-marked groove, which transmits
the tendons of the tibialis posticus and flexor
digitorum longus; the apex of the malleolus
is below, and gives attachment to the deltoid or
internal tibio-tarsal ligament.

The fibula, as it approaches the foot, becomes
suddenly enlarged in size, applies itself firmly
to the tibia, and then descends nearly an inch
and a half below its point of union with that
bone. The prominence formed by the fibula
inthis situation isnamed the malleolus externus ;
itis much larger than the internal, and placed
behind and somewhat below it. The external

_ surface of this fibular malleolus is covered

merely by the integuments ; the internal surface

152

is tipped with cartilage, and convex in the ver-
tical direction, being received upon a corres-
ponding concavity on the outer side of the
astragalus; upon the lower and back part of
this inner surface may be seen a deep depres-
sion, where the posterior fibulo-tarsal ligament
arises ; the anterior edge of the malleolus is
sharp, and gives origin to the anterior fibulo-
tarsal ligament; the posterior edge is marked
by a deep groove, which transmits the tendons
of the peronei muscles, longus and brevis.
The apex of the malleolus is below, and gives
origin to the middle fibulo-tarsal ligament.

The astragalus enters into the formation of
the ankle-joint by its superior surface, and a
portion of its two lateral surfaces. On the
superior surface we observe, anteriorly, a well
marked groove forming part of the neck of the
astragalus ; into this groove the anterior tibio-
tarsal ligament is inserted. Immediately be-
hind the groove we meet with an articulating
eminence of an oblong quadrilateral form, an
inch and a half in its antero-posterior, and about
an inch and a quarter in its transverse measure-
ment ; (this transverse measurement is, however,
a little greater in front than behind;) the emi-
nence is remarkably convex from before back-
wards, and concave from side to side; the outer
edge somewhat more elevated than the inner ;
it is completely covered with cartilage, and cor-
responds to the articulating cavity upon the in-
ferior exremity of the tibia. Upon the inner
side of the astragalus, we find a small articu-
lating surface of a triangular form, with the
base above and apex below; it is convex in
the vertical direction, and is tipped with car-
tilage prolonged ftom the superior surface:
upon thetriangular surface the internal malleolus
plays; the remaining portion of the inner side
of the astragalus is rough, and occupied chiefly
by the insertion of the internal. tibio-tarsal
ligament. The external side of the astragalus
is also marked by an articulating surface of a
much greater size for the reception of the ex-
ternal malleolus: it too is of a triangular form
with the base above; concave in the vertical,
and slightly convex in the antero-posterior
direction.

b. Ligaments.—We have already compared
the mechanism of this joint to that of the tenon
and mortise ; the mortise cavity, however, is not,
as we have seen, cut out of a solid bone, but
being formed in great part in the lower extremity
of the tibia, is completed on the outer side b
the fibula, which is firmly united with the tibia
by strong ligaments, forming what is called the
inferior tibio-fibular articulation. We shall not
now describe the ligaments which here unite the
tibia and fibula, referring to the article on the
TIBIO-FIBULAR ARTICULATION ; but we must
observe that, however it may be advisable, ‘in
anatomical descriptions, to separate this last
named articulation from the ankle-joint, they
are perfectly inseparable in their functions, the
integrity of the latter being essentially dependent
on that of the former: indeed it may be said,
that, by virtue of the great strength of the liga-
mentous connexion between the tibia and fibula
in the former articulation, the mortise is as

JOINT OF THE ANKLE,

strong, nay, in some respects stronger, than if it
had been formed out of solid bone. 8

The ligaments which connect the tenon and
mortise together, or to speak more literally,
which tie the tibia and fibula with the tarsus,
are five in number, namely, two tibio-tarsal
and three fibulo-tarsal ligaments.

1. The internal tibio-tarsal ligament is also
called the internal lateral, and by Weitbrecht
the deltoid ligament. There is, however, no
reason why we should not apply to it likewise
that principle of nomenclature which is so gene-
rally and with such advantage applied to other
ligaments. It arises by a truncated apex from
the point of the inner malleolus, and from the
little fossa at its outer surface ; its fibres change
as they proceed downwards and are fixed into
the inner surface of the astragalus and os calcis,
some proceeding as far forwards even as the
scaphoid bone. The posterior fibres are strong
but short; the anterior are much larger and
not so thick. Its internal surface is lined by
the synovial membrane of the joint; and on its
internal surface it is covered by the tendon of
the tibialis posticus, and it sends some of its
fibres to the sheath of the flexor longus
digitorum tendon. In flexion of the leg the
anterior fibres are relaxed, and the posterior are
rendered tense: in extension the reverse of
course takes place. 2. The anterior tibio-
tarsal ligament (lig. tibio-tarsal, Cloquet) con-
sists of a few loose fibres scattered over the
synovial membrane, and in some instances so
delicate and so separated by pellicles of fat as
to be scarcely perceptible. They arise from
the fore part of the inner. malleolus and the
adjacent anterior portion of the tibia, and de-
scend obliquely downwards and outwards to
be inserted into the neck of the astragalus.
This ligament is covered anteriorly by the ten-
dons of the tibialis anticus, extensor proprius
pollicis, and extensor digitorum longus: poste-
riorly it isin contact with the synovial mem-
brane. 3. The anterior fibulo-tarsal ligament
(lig. fibule anterius, Weitb., anterior external
lateral, Boyer) arises from the anterior edge of
the outer malleolus, a few lines from its ex-
tremity; it descends obliquely forwards and
inwards, and is fixed into the astragalus imme-
diately in front of the articulating surface which
receives the fibula: it is scarcely an inch in
length, of an oblong quadrilateral form, and is
frequently subdivided into two distinct parts.
In extension of the foot it is rendered tense;
in flexion it is relaxed. 4. The middle fibulo-
tarsal ligament (lig. fibule medium perpen-
diculare, Weitb., external lateral ligament,
Clog.) is a round fasciculus of fibres having
almost the appearance of a tendon which arises
from the apex of the external malleolus, de-
scends obliquely backwards, and is attached
to the outside of the os calcis. It does —
not appear to us that in any position of the |
joint this ligament takes a perpendicular course, —
although that epithet has been applied to it by —
Weitbrecht. It is related superficially to the —
peroneus longus tendon, and by its deep sur-
face to the synovial membrane, to the astra-
galus, and os calcis. In flexion of the foot this

‘4

a

4
é-
4
4
a
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a eee Bae f

surfaces.

JOINT OF THE ANKLE, 153

ligament is rendered tense; hence it appears
designed to limit motion in this direction: in
extension it is of course relaxed. 5. The pos-
terior fibulo-tarsal ligament lig. fibule posterius,

Weitb., posterior external lateral, Boyer) arises .

from the little fossa upon the inner and back
part of the outer malleolus; it passes backwards
and inwards almost horizontally, or at least de-
scends yery slightly, and is inserted upon the
back part of the astragalus into the outer edge
of that groove which transmits the flexor longus
pollicis tendon. This ligament is stronger than
either of the two preceding, and is frequently
divided into several distinct. fasciculi. From
its superior edge an accessory band sometimes
passes upwards and inwards over the synovial
capsule to be fixed into the tibia. Walther
has described this band under the name of the
oblique ligament, and it is well represented by
Weitbrecht (fig. 65, tab. xxii.)

The synovial membrane of the ankle-joint is
of very great extent: it lines not only the
articular surface of each malleolus, the several
ligaments we have just described, and the
articulating cavity upon the lower portion of
the tibia, but it is prolonged upwards between
the tibia and fibula, forming in that situation a
little cul-de-sac : this, however, is merely for the
extent of a few lines, for its further progress up-
wards is interrupted by the inferior interosseous
ligament, (fig. 61.) From the circumference
of the tibio-fibular mortise the synovial mem-
brane passes downwards upon the astragalus,
covers its superior articulating eminence, and
sends prolongations upon its lateral articulating
It is remarkably loose upon the
anterior and posterior parts of the joint, and is
said to contain a greater quantity of synovia

than any other synovial membrane in the body.

Certainly its strength is much increased by
those scattered fibres to which we have given
the name of anterior tibio-tarsal ligament :

steriorly it is weakest, for here few if any
igamentous fibres can be detected, though
sty and Weitbrecht speak confidently of
such.

¢c. Mechanism and function of the ankle-joint.
—To understand properly the mechanism and
function of the ankle-joint, we must carefully

contemplate it in the opposite conditions of rest

and motion.

_ 1. Viewing it, then, in the first place, as the
individual stands at rest, we observe that the

_____ leg and foot meet each other in the ankle-joint

at a right angle, and we are particularly struck

with this fact upon finding that this disposition

occurs in scarcely any other animal than man.
This interesting fact in comparative anatomy is

by no means an accidental arrangement; its

design is obviously in reference to the proper
a of the body in each animal. It has,

or instance, frequently been alluded to as one
of the many anatomical proofs that the erect

position is natural to the human subject : had

the leg and foot been articulated at any other
than a right angle the upright position of the
body could not be maintained, at least without
great and incessant muscular exertion. Another

point worthy of our attention is that when the
ankle is at rest and the body in the upright
position, the fibula plays no part in the func-
tion performed by the joint: it is the tibia
alone which receives the weight of the body,
and transmits it to the astragalus. This fact
should be carefully borne in mind, for it has
considerable influence upon the accidents so
frequently occurring here. The astragalus, from
the way in which it supports the body, has often
been compared to the key-stone of an arch, the
arch being represented by the foot. That the
foot presents an arched concavity at its lower
part cannot be doubted ; but it is by no means
so certain that this is designed upon the prin-
ciple of the architectural arch to support the
weight of the body: in fact, the astragalus,
which receives the entire weight, does not cor-
respond to the centre of this arch. The true
design of the vaulted form of the foot is to
permit its accommodating itself to the several
irregularities of surface which, both in standing
and progression, it must encounter.

The motions of flexion and extension are the
only ones permitted at the ankle-joint. In
flexion the astragalus rolls from before back-
wards in the tibio-fibular mortise; it may be
continued until the foot and leg form with
each other an angle of about sixty degrees ;
at this point further flexion is prevented, partly
by the tension of the middle fibulo-tarsal liga~
ment, and still more effectually by the neck of
the astragalus coming into contact with the
lower edge of the tibia. In flexion the anterior
tibio-tarsal and fibulo-tarsal ligaments are both
relaxed ; the posterior and middle fibulo-tarsal
are rendered tense; the internal tibio-tarsal
ligament has its posterior fibres stretched and
its anterior ones loosened. 2. In extension
the foot not only returns to its rectangular posi-
tion with the leg, but may even be carried
beyond this, so as to form with the tibia an
obtuse angle of about one hundred and fifty
degrees.* Further extension is at this point
prevented by the tension of the ligaments which
lie in front, and also by the astragalus behind
coming into contact with the lower edge of the
tibia. During extension the astragalus rotates
forwards in the tibio-fibular mortise; the pos-
terior ligaments are relaxed, the anterior are put
upon the stretch, the state of each individual
ligament is, in short, reversed from what we
have just described as its condition in the
opposite motionofthe joint. 3. A slight degree
of lateral motion of the ankle is perceptible in
the dead subject, but during life it cannot be
said to exist: hence, in the classification of
Cloquet and Bichat, the joint is properly
ranked under that variety of ginglymus to which
we apply the term “perfect.”

The ankle is the analogue of the wrist-joint
in the superior extremity, and accordingly,
though there are certain points of difference ©
between them, the general character of both is

* According to Hildebrandt the angle of flexion

is 45°, and the angle of extension according to
Rosenthal (Handb.. der Chir. Anat.) is 175°.— Ep.

154 ABNORMAL CONDITION OF THE ANKLE-JOINT.

the same. It is no less interesting than instruc-
tive to contrast these two articulations with
each other, for in doing so we find that the
modifications of structure here, as well as in
all other instances, are referable to the peculiar
function which each part is destined to perform.
The hand in the human subject is exclusively
an organ of prehension ; the foot is one merely
of support :—now this simple fact at once fur-
nishes us with a clue to all difficulties. The
great strength and sudden expansion of the
tibia and fibula at the ankle, are evidently a
provision to sustain the weight of the body and
to increase the basis of its support; in the
radius and ulna such size and strength would
have been to no purpose, and hence these bones
at the wrist are comparatively thin and delicate.
At the ankle we should naturally have expected
frequent dislocations, owing to the great weight
from above, and to the great mobility which for
the purposes of progression must at the same
time necessarily exist here ; these are two most
formidable causes of displacement ; but, as if in
compensation, we find two strong buttresses (the
malleoli) projecting one upon either side of the
joint, and rendering such displacement, under
ordinary circumstances, almost impossible. At
the wrist, where there is no weight to be sup-
ported, such lateral splints would have been
superfluous: hence the imperfect and almost
rudimental malleoli of the radius and ulna;
hence the shallow and imperfect cavity ;
hence, in a word, the anatomical confor-
mation which constitutes the ankle-joint a
ginglymus, and the wrist an arthrodia. In
the motions of the ankle and wrist-joints we
observe likewise a striking difference: in the
former, lateral motion would have been super-
flous in reference to the function of the foot ;
at the wrist, on the contrary, a free lateral mo-
tion is indispensable to increase the sphere of
action of the hand.

For the BIBLIOGRAPHY of this article, see that

of ARTICULATION.
(John E. Brenan.)

ANKLE-JOINT, ABNORMAL CONDI-
TION OF THE.—The deviations from the na-
tural or normal condition of the ankle-joint may
be classed under those which are referable to
accident and to disease: any defects which
may be considered to result from congenital
malformation shall be elsewere treated of.
(See Foor.)

Accidents—The different structures which
immediately compose the ankle-joint, as well
as those which surround this articulation, and
are merely accessary to its functions, are, each
and all, liable to numerous accidents, the most
important of which we shall here advert to.

hese accidents may affect the tendons, the
ligaments, or the bones.

Tendons.—Those tendons which pass behind
the inner and outer malleoli are occasionally
displaced ; and, although the accident must be
considered a rare one, it ought not here be
overlooked.

« The two peronei extensor muscles,” says
the late Mr. Wilson,* ‘ where they pass behind
and below the fibula over a smooth lubricated
surface of that bone, are bound to it by a strong
ligament; but should the ligament give way,
one or both of these tendons may escape from
the groove or pulley in which they usually play,
and being thrown forwards over the edge of
the bone, in this new situation their action on
the foot will be to bend it on the leg, when in
their natural position it was to extend it. The
peronei having been habituated to act with the
extensor muscles, continue to contract at the
same time with them, but now they oppose
the effect which formerly in conjunction with
the extensor muscles they produced upon the
foot, and by so doing excite much pain and
irritation in addition to the lameness. When
this situation of the tendon is discovered early,
the tendon can be readily restored to its proper
place, but if this is not done, it forms a new
groove on the fore part of the bone, and the
old one is filled up, or otherwise so altered
that it cannot receive the tendon, and thus the
pain and lameness may continue for life.
I have seen this occurrence sometimes in the
living body early enough to return the tendon,
and have been consulted in cases where it
could not be returned; in one, where the pain
was so violent that I recommended the divi-
sion and removal of part of the tendon; the
muscle then contracted to its full extent, and
afterwards shrunk, and no inconvenience was
felt after the operation. I have met with two
or three instances of this kind of displacement
of tendons in bodies brought into the dissect-
ing-room ; but of the previous history of the
cases I could know nothing.” Mr. Wilson
adds, “‘ Those tendons which pass in grooves
behind the inner ankle are liable to a similar
displacement.” Of the latter,accident we have
known but one instance, but of the former
several.

Ligaments. — Accurate anatomical investi-
gations of the actual condition of the various
structures which compose the ankle-joint,
when affected by a sprain, have shown that
in slight cases of sprain of this joint no-
thing unnatural has been discovered, as the
bonds of union between the bones have been
merely stretched or strained. In others more
severe, the ligaments have been found broken
or torn from their attachment to the bones,
the synovial sac opened, and its fluid to have
escaped from the cavity of the joint; the cel-
lular tissue around has been filled with extrava-
sated blood, and with synovial and serous fluids.
In these cases the nerves, bloodvessels, ten-
dons, even the skin itself, have been subjected
toa degree of stretching and extension, more
or less considerable. Baron Dupuytren, from nu-
merous observations on the living subject, from
post-mortem examinations, and experiments, is
of opinion that a slight accidental torsion of the

foot inwards or outwards, amounting to a
sprain, only produces an injury, in which ©

* Wilson’s Lectures on the Bones, &c.

—— ee.

—<——_

a a ee a

‘

J
:
J
=
x

ABNORMAL CONDITION OF THE ANKLE-JOINT. 155

the ligaments are merely stretched ; but that a
greater effort produces a separation of the
lateral ligament from one or other of the mal-
leoli by laceration of its compact tissue, or of
the periosteum which covers it, while the liga-
ments themselves remain unbroken. Oppor-
tunities do not often occur of discovering
the effects of sprains on the joints by anato-
mical examination made at various periods
after the accident; but although Dupuytren’s
Opinion may be correct as to the majority of
cases, still others have found the lateral liga-
ments ruptured across, instead of having been
torn from the bone. Mr. Wilson found, in
a case where the patient died five days after
a severe sprain of the ankle-joint, that the del-
toid ligament binding the tibia to the foot was
lacerated, and that the synovial membrane of
the ankle-joint was also much torn. In older
cases he found evidences of chronic inflamma-
tion in the ligamentous structures around the
joint; that these structures were thickened
and vascular, and had lost much of their plia-
bility.

The pain and inability to walk, the sudden
effusion around the injured ankle, the ecchy-
mosis, tenderness of the skin and tension,
the signs of this injury expressed by the living
structures, are all accounted for by the lesions
which an anatomical examination of these in-
juries of the ankle-joint discovers. This also
explains what practical writers have noted of

’ sprains, viz. that sometimes the ankle-joint

which has been affected by this accident,
oy and perfectly recovers,—that, on the
other hand, it is not unfrequently so weakened
by the injury, as to become peculiarly suscep-
tible of a renewal of the sprain from slight
causes ; sometimes the articulation contracts a
rigidity, by which for a time, or even for life
itself, its proper functions are interfered with,
and a permanent edema of the soft parts
around the joint is too often in these cases
established.

Bones. — The bones which contribute to
form the ankle-joint are liable to fracture and
to luxation. These bones, we know, are the
tibia, fibula, and astragalus; for an account of
the accidents which affect the latter particularly,
we refer to the article Foor, and shall here,
as succinctly as we can, notice the various dis-
placements of the bones of the leg at the
ankle-joint, which have been observed to be
the result of a fracture through one or both
of the malleoli, or of an accidental rupture of
ad ligaments which tie these eminences to the

t.

When we reflect on the great strength of the
ligaments which connect the astragalus to the
tibia and fibula, and the support which the ar-
ticulation derives from the prolongation down-
wards of the malleoli, we can easily perceive
that a luxation of the foot must be the effect
only of some very violent cause, and that this
accident can very rarely (in a true sense) be a
simple one. Effusions of blood, rupture of all
the surrounding ligaments, fracture of the
external or even of both the malleoli, wounds
of the soft parts, and even protrusion of the

bones, are contingences which frequently render
the dislocation of the tibia at the ankle-joint
a very complex accident.

The most superficial view of the structure
of the ankle-joint will convince any one that
no lateral displacement of the bones of the
leg can occur, without its having been im-
mediately preceded by a fracture of either the
tibial or peronzal malleolus ; but such a view
would warrant the conjecture, that a luxation
in the direction forwards or backwards may
possibly take place, simply from the rupture
of the ligaments of the joint alone, and the
action of muscles. Such a luxation as this
last, when no fracture exists, should be best
entitled to the name of simple; yet those
luxations of this articulation (such is the
vagueness of surgical language), whether ac-
companied with fracture or not, are all called
simple, provided there be no wound through
the integuments communicating with the cavity
of the joint. In this latter case alone the
luxation is denominated compound, of which
it is not our intention here to treat.

We shall arrange the luxations of the bones
of the leg at the ankle-joint in the above sense
called simple luxations, into those which occur
in the direction inwards, outwards, forwards,
and backwards, and each of these, it is be-
lieved, may be a partial or a complete lux-
ation.

Luxation of the Tibia inwards.—This luxa-
tion may be complete or incomplete: we
shall first treat of the most common form of it
or that termed partial Dislocation of the Tibia
inwards from the Astragalus, or Pott’s luxation.
Mr. Pott, in describing this accident, observes,
“that the support of the body, and the due
and proper use and execution of the office of
the joint of the ankle, depend almost entirely
on the perpendicular bearing of the tibia upon
the astragalus, and on its firm connexion with
the fibula. If the former bone is forced from
its just and perpendicular position on the
astragalus ; or, if it be separated by violence
from its connexion with the latter, the joint of
the ankle will suffer a partial luxation inter-
nally: this is the case when, by leaping or
jumping, the fibula breaks in its weak part,
within two or three inches of its lower ex-
tremity. When this happens, the inferior frac-
tured end of the fibula falls inwards towards
the tibia, that extremity of the bone which
forms the outer ankle is turned somewhat out-
wards and upwards, and the tibia, having lost its
proper support, and not being of itself capable
of steadily preserving its true perpendicular
bearing, is forced off from the astragalus, in-
wards, by which the ligaments are torn, thus
producing a perfect fracture and a partial dis-
location.” *

If we are called to examine a patient who
has recently suffered this accident, we find that
the ankle-joint now possesses some degree
of lateral mobility. In the normal state of the
ankle-joint we know that the quadrilateral
cavity formed by the tibia and fibula for the

* Pott’s Works by Earle, vol. i. p. 327.

156 ABNORMAL CONDITION

reception of the astragalus, makes with the
latter a perfect mortise joint, which admits
of motions of flexion and extension, but
allows of no motion whatever laterally or
horizontally; for it must. be recollected that
those motions of inclination of the foot, known
under the names of adduction and abduction,
are not movements in the ankle-joint, but take
place in the joints of the tarsus: but the un-
natural mobility in question is very great when
the fibula is broken at its lower part; this is
shewn, when, after the surgeon has bent the limb
to relax the muscles, the leg is fixed by one
hand placed at its lower extremity, whilst the
other moves the foot from within outwards;
the foot is then seen to move in a transverse
line and to quit the axis of the leg; the mal-
leolus internus projects inwards, and the mal-
leolus externus is moved upwards and out-
wards, and all these appearances vanish, when
by a contrary movement we bring the foot to
its natural position.

When we leave the limb for a moment to
itself, we notice that there is a remarkable
change in the point of incidence of the axis
of the leg upon the foot. The tibia and upper
fragment of the fibula, although really remain-
ing in their natural position, appear driven in-
wards, while the foot is rotated outwards.

The changes of direction of the leg and foot
are such, that if the axis of the leg were pro-
longed inferiorly, instead of falling on the
astragalus, it would leave this bone, and con-
sequently the whole foot, more or less on its
outer side; hence the impossibility patients
experience of bearing upon the foot , which
only presents its inner edge to the ground.

Fig. 51.

LL

LLL
LL

Partial luxation of the Tibia inwards, or Pott’s
luxation.

OF THE ANKLE-JOINT.

This change is a necessary and constant effect
of the displacement of the foot, when the-
fibula ceases to support it on the outer side,
and when the peronei muscles begin to con-
tract. The foot and external malleolus which
make part of one system, move in one direc-
tion; the tibia and upper fragment of the fibula
move, or, to speak perhaps more correctly,
remain, in another. The centre of this new
motion is no longer in the articulation, but, >
in an oblique line, passing through the joint, ;
and extending from the malleolus internus to
the point of fracture of the fibula: this line is
well expressed in fig. 51, representing the frac-
ture of the fibula, and taken from the engray-
ing which accompanies the work of Pott.

The retiring angle seen (fig.51, 52, a) in this
partial luxation of the tibia inwards, on the
outer part of the articulation, and the pro-
jecting one (6) existing at the inner, consti-
tute the most striking features of the accident ;
these angles correspond exactly to the extremi-
ties of the line above-mentioned, in the direc-
tion of which the weight of the body acts, when
the foot being turned outwards this line may
be seen to traverse the leg obliquely from the
lower part of the upper fragment of the broken
fibula to the malleolus internus.

We cannot omit to notice also, that there is
in all these cases a remarkable rotation of the
whole foot on its long axis, in such a direction
that the upper surface of the astragalus looks |
obliquely upwards and inwards, (fig.52,¢, ) the
inner edge of the foot is turned downwards,
the sole inclined outwards, the outer edge
raised, and the dorsum turned directly upwards.
The extent of this rotatory motion is besides
always proportioned to the displacement out-
wards; both are attributable to the same causes,
viz. the weight of the body, and the action of
the peronzi muscles, when the patient has at-
tempted to walk after the fracture has occurred.

It is on these combined movements when
not corrected by a proper mode of treatment,
that the deformity of the foot, and all the
consequent difficulties in walking, depend.

Complete luxation of the tibia inwards from
the astragalus, complicated with a simple frac-
.ture of the fibula—This is a very severe, and,
fortunately, a very rare accident. In alluding
to it, Dupuytren says,* that “ the foot is not
only susceptible of being carried outwards, but
also upwards at the same time; a double
displacement, which he had observed to occur
only once in 200 cases of fractures of the
fibula treated in the Hotel Dieu for fifteen
years, “ but the case was so marked,” he says,
“ that in future it cannot be mistaken or passed
over in silence.” It cannot occur unless the
fibula is fractured ; for this condition is indis- —
pensable to any displacement of the foot in-
wards or outwards; it requires besides a com-
plete laceration of the short thick ligaments —
placed between the tibia and fibula, the strength
of which is such that, in most experiments on

* Sur la Fract. de ’Extremité inferieure du Pe-
roné, in Annuaire Med. Chir. des Hopitaux de
Paris, 1809, 4to. and folio. , j

ABNORMAL CONDITION OF THE ANKLE-JOINT.

the dead subject, they resist more powerfully
than the structure of the bones themselves.

It was as a consequence of the fracture of
the fibula and a rupture of these ligaments,
that, in the case alluded to, the astragalus was
seen dislocated outwards, and then drawn up
on the outer side of the tibia. In short, the
astragalus, the malleolus externus, and the foot,
which formed but one system ef parts firmly
connected, were drawn first to the outer side of
oe leg, and then two inches upwards on the
tibia.

A carpenter, aged fifty-four years, was ad-
mitted into the Hotel Dieu, in February, 1816.
His right leg presented all the signs of fracture
of the fibula at its inferior part, such as devia-
tion and rotation of the foot outwards, promi-
nence of the tibia, and of the inte:nal malleolus
inwards, depression and crepitation above the
outer ankle; but that which most attracted the
attention was, 1st, the shortening of the limb,
and, 2dly, the enormous increase in breadth of
the space which should naturally intervene be-
tween the two malleoli. The sinking down of
the lowest part of the tibia, even to the level of
the sole of the foot, where the projection of the
internal malleolus could be felt, the elevation of
the astragalus, of the peroneal malleolus, and the
whole of the foot along the external surface of
the tibia, even to two inches, were all symp-
toms quite unusual in fracture of the fibula,
and left no doubt that the ligaments which
stretched inferiorly from this bone to the tibia
had been lacerated, and that the foot, yielding

|
mn

ill

Complete luxation of the
tibia inwards or of the foot
outwards and upwards,—

Dissection of a case of
the same class as fig. 53,
from the museum of St.

to a violent effort from within outwards, and
from below upwards, had been luxated in these

directions, and had carried with it the peroneal
malleolus. This then is evidently a case of
complete dislocation of the tibia inwards, or,
as the French writers would call it, a luxation
of the foot outwards and upwards.

Although this species of luxation has not
been specially described in any of our English
works, I doubt not but such an accident has
been observed, although it is possible that its
nature was not always clearly understood. Sir
A. Cooper, in his valuable work on Disloca-
tions and Fractures, states that the foot has also
been known to be thrown upwards, between
the tibia and fibula, by the giving way of the
ligament which unites these bones; but he
adds that this accident is only an aggravated
form of an internal dislocation.

We find but little difficulty in comprehend-
ing how the accident described by Dupuytren
may occur, because, the fibula having been
first fractured, the broken bone and ruptured
ligaments permit the foot to yield to the
powerful action of the muscles on the back
“ and outside of the leg, which draw it at

rst outwards, and then upwards ; but on the
contrary, it is not easy to imagine any force
capable of overcoming the resistance of the
many inter-osseous ligaments which exist, and
of the fascize and annular membranes which
surround the bones of the leg: a force must be
great indeed which can overcome the muscles
also, and cause a divarication of the bones of the
leg sufficient to permit the astragalus and rest

( Dupuytren, ) Thomas’s Hospital.

of the foot to be thrown upwards between the
tibia and fibula. Supposing this last case pos-
sible, the shortening of the limb and its newly-
acquired breadth between the malleoli might
lead to error, and the two cases here alluded to
be at first sight confounded; but in Dupuy-
tren’s case, the fracture of the fibula, the over-
lapping of its fragments, and above all the
ascent of the external malleolus, so much above
the level of the internal, will always constitute
such characteristic marks, that when such an
accident presents itself, we conceive it cannot
be confounded with any other injury of this
articulation.

What are the anatomical characters of this
complete luxation of the tibia inwards, with
displacement of the foot and outer malleolus
upwards and outwards? It is evident that
there must be very extensive injury done in
such cases to the ligaments and bones ; the fibula
must be fractured near the ankle, and it is
probable that some fragments of the tibia may
be carried off with the fibula, for such is the
strength of the ligaments between the lower part
of the tibia and fibula, where these unite for
the reception of the astragalus (vid. fig. 61), that
there is reason to believe that the bone itself
would break before the ligaments would yield.
If a portion of the tibia, however, is not broken
off and carried with the fibula, these transverse
fibrous bands must be torn, as well as those

158

_ oblique ‘ligaments which pass before and be-
hind from the fibula to the tibia. The proper
interosseous membrane itself must be detached
from between the bones to allow the astragalus
to ascend along the outside of the tibia. While
the ligaments which connect the outer malleolus
to the tibia must be torn, those which unite it
to the foot remain entire, the deltoid or internal
lateral ligament must be completely torn across,
as well as the synovial sac of the articula-
tion ; nor should it be forgotten that the annu-
lar ligaments and strong fascie at the lower
part of the leg, must, in so severe and ex-
tensive an injury, be lacerated; the tendons,
muscles, and other structures may escape injury,
the astragalus and outer malleolus are dragged
up (fig. 54, a, 6), their ascent being only limited
by the lower point of the upper fragment of
the fibula (c), which remains in its natural
relation to the tibia, except that it must be
somewhat approximated to it; the lowest point
of the superior fragment of the broken fibula
rest upon the summit of the articular pulley of
the astragalus, as is well seen in a preparation
preserved in the collection of St. Thomas's
Hospital Museum, the delineation of which we
have borrowed from Sir A. Cooper’s work. The
preservation of this specimen, which in our
mind is a true example of the complete dislo-
cation of the tibia inwards, and of the external
malleolus astragalus and foot upwards and
outwards, is a new proof of the truth of the
observation we have above made, that this
severe accident had not altogether escaped the
notice of English surgeons, although the
“ Annuaire” contains the first accurate account
of the external signs by which it may be recog-
nized in the living subject.

Luxation of the tibia outwards, complicated
with simple fracture of one or both of the mal-
leoli.—This, it is said, is one of the most dan-
gerous of the dislocations to which the ankle is
liable, for its production has been noticed to
be attended with greater violence, and to be
accompanied by more contusion of the integu-
ments, more laceration of ligaments, and greater
injury to bone, than we have occasion to ob-
serve in the production of the other luxations
of this joint.

Theastragalus in thisaccident is carried towards
and helowthe external malleolus (fig. 55), whilst
the outer edge of the foot is turned downwards,
its inner edge upwards, and the sole inwards,
the tibial malleolus disappears, and is hidden
at the bottom of a retiring angle formed by the
inner side of the leg and foot, and the peroneal
malleolus forms, with the astragalus, a salient
angle rounded off on the outside. Looking
only to the change of form, situation, and rela-
tive position of the leg and foot, we might sup-
pose the case one of congenital club-foot.* The
luxation of the tibia outwards, with inversion
of the sole of the foot, is one of the most rare
and most difficult cases to explain. Its pro-
duction must be the result, we suppose, of co-
incidences rare and unusual. There may be a
certain obliquity in the line of direction of the

* Dupuytren, Annuaire.

ABNORMAL CONDITION OF THE ANKLE-JOINT.

Fig. 55.

Dissection of the luxa-
tion outwards ( Museum
of St. Thomas’s Hospi-
tal). [Fig. 55.]

Luxation outwards of the
tibia and fibula with ob-
lique fracture of the tibia.

fracture coinciding with a considerable degree
of resistance in the lower fragment of the fibula:
thus, if we can suppose that a fracture shall
traverse the tibia obliquely from above down-
wards, and from within outwards, so that the
point of the upper fragment be directed down-
wards and outwards, and the lower fragment point
upwards and inwards, and if to this obliquity
we suppose added a certain resistance on the
side of the lower fragment of the fibula, it is
plain that the foot being unable to turn out-
wards, must be carried inwards by the action
of the muscles, and with this inversion, &c.
some little shortening of the limb, at least
when measured on its inner side, may be ex-
pected.

If this accident be neglected, the cure which
nature attempts is very imperfect, the ankle-joint
becomes stiff and rigid (fig. 56:), the interval be-
tween the internal and external malleolus is
much increased, the latter presses heavily

against the integuments, which, when the limb

is much exercised, have a strong tendency to
inflame and suppurate, the outer edge of the
foot throughout its whole line presses the
ground, whether the patient be standing or
walking, while the inner edge is somewhat
elevated and curved inwards. In the dissec-
tion of this accident, it will be found that the

ABNORMAL CONDITION OF THE ANKLE-JOINT.

malleolus internus is fractured, and in general,
we suppose, with the obliquity from above
downwards, and within outwards, above de-
scribed. The deltoid ligament remains un-
broken, the capsular membrane is torn in front,
the fibula has been found obliquely fractured,
as well as the tibia, or the three ligaments
which connect it to the tarsus have given way ;
none of the tendons suffer, and hemorrhage to
any extent in these cases seldom or never occurs,
as the large arteries generally escape injury.

Luxation of the tibia and fibula forwards,
and also luxation of these bones backwards from
the articular pulley of the astragalus, without
Jracture—In the simple and complete luxa-
tion of the bones of the leg forwards at the
ankle-joint, (without fracture,) the articular
pulley of the astragalus is placed behind the

_ inferior extremity of the tibia, which last rests
partly on the superior surface of the neck of
the astragalus, and partly on the os naviculare.

Tn the simple and complete luxation of the
tibia backwards, (without fracture,) the inferior
extremity of the tibia is placed behind the arti-
cular pulley of the astragalus, and corresponds
to the posterior part of the superior surface of
the os calcis. In both these luxations, the na-
tural connexion with each other of the bones of
the leg remains undisturbed, and the two mal-
leoli advance or recede together, according to
the direction in which the displacement has
occurred. In both, the capsular membrane and
the posterior and lateral ligaments must be ex-
tensively lacerated, and most of the flexor and
extensor tendons, in some degree, put upon the
stretch.

The luxation of the bones of the leg forwards
cannot take place, but in a forced and sudden
extension of the leg on the foot, when the latter
being retained by some obstacle, and solidly
supported, we fall backwards.

e luxation of the tibia backwards, on the
contrary, cannot happen unless when the foot
is strongly flexed, the toes being elevated and
retained in this position, we fall forwards.

Authors have seldom failed to notice these
simple luxations forwards and backwards of
the bones of the leg, yet for our part, no mat-
ter to what source we apply for information,
we cannot satisfy our minds that we can adduce
a single well-marked example of luxation of
the bones of the leg at the ankle-joint, unac-
companied by a fracture of one or both of the
malleoli ; we would not, however, be under-
stood to deny the possibility of such an occur-
rence, but merely to state our conviction that
such an accident must be exceedingly rare.

We have now to consider luxations of the
tibia from the astragalus, forwards and back-
wards, when complicated with a simple frac-
ture of the fibula or tibia close to the articula-
tion: these may be complete or partial.

Complete luxation of the tibia forwards from
the articular part of the astragalus compli-
cated with a simple fracture of the fibula—
This accident may arise from the same causes
nearly as those which may be supposed to
influence the more simple luxation in the same
direction; and as we know that when the

159

fibula is fractured near its malleolus, the pe-
ronei muscles may under certain circumstances
effect a luxation of the tibia inwards, so that
displacement which we are now considering
may be the result of the action of the gastro-
cnemius and soleus. These acting on the foot,
which in consequence of the fracture is no
longer fixed by the malleolus externus, cause
the astragalus to slip from before backwards,
and the lower end of the tibia forwards, and
move the lower fragment of the fibula in such
a manner that its malleolar extremity is carried
backwards, and the upper part forwards. This
action of these muscles, however, only pro-
duces a very incomplete dislocation whenever
the internal malleolus is uninjured, or the foot
in this case being carried outwards and back-
wards at the same time; but when, as often
happens, either the internal malleolus or del-
toid ligament is broken, this displacement may
be as complete and direct as the simple dis-
location forwards of the tibia. We then find the
foot lengthened behind and shortened in front ;
a semicircular excavation occurs in the former
direction, and an osseous tumour raises the
tendons and ligaments on the front of the
ankle, but it is to be particularly remarked
that, whilst in the simplest form of luxation
of the tibia, i.e. where there is no fracture,
the external malleolus follows the tibia and
fibula, and forms a projection corresponding
to that of the internal, it is in this case
dragged backwards with the foot to which it
is attached by the lateral ligaments, and no
longer has the same direction as the bones of
the leg.

In the dislocation forwards of the tibia
(whether simple or complicated with a frac-
ture of the fibula) from the astragalus, the
articular pulley of this bone is placed behind
the inferior articular cavity formed for it in the
tibia; but this latter bone at the same time,
it will be recollected, must now rest on the dor-
sum of the tarsus, where it is formed by the upper
part of the neck of the astragalus and os navi-
culare. When the tibia has thus once advanced
before the articular pulley of the astragalus, the
luxation forwards is as complete as it well can
be; in our opinion, to imagine any more com-
plete luxation of the tibia forwards, we should
be obliged to presume that this bone in its
advance on the dorsum of the foot had com-
pletely cleared the astragalus, and then rested
“on the os naviculare and os cuneiforme in-
ternum,”* which last form part of the anterior

* The weight that so justly attaches to any ob-
servations from Sir A. Cooper, ‘induced us to con-
sider well the account he gives of the dissection of
this complete luxation of the tibia forwards, in his
work on Dislocations and Fractures; and we find
that we cannot reconcile it with onr ideas of the
anatomy of the injury. We are sorry in this in-
stance to be obliged to differ from an authority,
to which we feel indebted for many observations
copied into these pages; but we think there must
be error in the following passage taken from the
valuable work to which we allude, page 178, 8th
edition.

«< On dissection, the tibia is found to rest upon
the upper surface of the os naviculare and os cunel-

160

range of the tarsus, a situation which the tibia
could not well occupy, without a previous
lesion of the tendons of the tibialis anticus,
and stretching of the other extensors: from
such a relative position of the bones of the leg
and foot would result a shortening of the dorsum
of the foot and an elongation of the heel to an
extent which, we believe, has never been no-
ticed.

Partial luxation of the tibia forwards, with
simple fracture of one or both of the malleoli.
—The complete luxation forwards of the tibia
from the astragalus, which we have described
_in the preceding section, all writers look upon
as the more common form of dislocation for-
wards ; while the partial luxation in this di-
rection is considered a rare accident. My
opinion upon this subject is quite different ;
for some experience in these accidents leads
me to say, that a complete luxation of the tibia
forwards from the articular pulley of the astra-
galus is rare, but that a partial luxation in this
direction accompanied with a simple fracture
of one or both of the malleoli, is an accident
by no means uncommon.

The signs of this partial luxation of the tibia
forwards are nearly the same as those we have
stated to belong to the complete luxation in
this direction ; they are, however, as might be
expected, more faintly marked, and, conse-
quently, may more easily be neglected; but,
after all, these signs are so evident, that it is
wonderful how with common attention they
can be overlooked. It may not be amiss to
subjoin the following case as illustrative of the
common partial luxation forwards :—

A man, aged twenty-two years, was ad-
mitted into Jervis - Street Hospital, at three
o'clock, a.m. of the 26th of December, 1833.
He stated that he and a friend had been
drinking together in a public house, that in
the middle of the night they quarrelled, that
he was knocked down, and was unable to rise,
in consequence of his having received a severe
injury of his left ankle: his friend then pro-
cured some assistance and carried him to the
hospital; at my visit, I found him in bed,
complaining of much pain, his leg extended
and resting on its outer side; the heel was re-
tracted, and between it and the calf of the leg,
instead of the ordinary line which marks the
course of the tendo Achillis, there was a
conspicuous semicircular curve, (fig. 57, a, 6);
in a word, the heel was lengthened, and the
dorsum of the foot seemed much shortened ;
in the situation of the ankle-joint in front,
there was a remarkably hard, prominent, trans-

forme internum, quitting all the articulatory sur-
face of the astragalus, excepting a small portion on
its fore part, against which the tibia is applied.”
Now, a single glance at the skeleton of a foot will
shew us, that a portion, however small, of the ar-
ticulatory surface of the astragalus, together with,
secondly, the upper part of the neck of this bone ;
thirdly, the os naviculare; and, fourthly, the os
cuneiforme internum, nearly form a space equiva-
lent to a third of the length of the whole foot,
an extent of surface, which, manifestly, the arti-
culating portion of the dislocated tibia could not
occupy.

ABNORMAL CONDITION OF TIE ANKLE-JOINT.

verse ridge made by the advance of the lower 4
extremity of the tibia and extensor muscles of
the toes, while beneath this there was a marked _
depression, where the skin and annular liga-_
ment seemed, as it were, pinched in, drawn

under the lower edge of the articular part of

the tibia; the foot was pointed downwards,

no movement of flexion or extension could be
communicated to the ankle-joint, but it ad- 3
mitted of some little motion in a horizontal, .
and also ina lateral, direction, when the leg

was firmly grasped with one hand and the foot
moved with the other. .

It was remarkable that, although the man
had no power whatever over the motions of
the joint, he could, while he lay in bed, move
his whole limb about with much freedom, and
(as there was probably a locking of the bones .
with each other) these voluntary movements . .
were not accompanied by any increase of

in.

The fibula could be felt to be fractured
about an inch and a half above the lowest
point of the outer malleolus, “ the foot, the
outer malleolus, and short portion of the
broken fibula, formed one system of parts,”
and were carried for the length of an inch or
more horizontally backwards, while there was
a projection forwards, of the lower articular
part of the tibia, and the internal malleolus
itself was advanced in the same proportion :
it is to be observed, that there was no crepitus,
because it was the deltoid ligament only which
was torn; the tibia was not broken, and
the ends of the fractured fibula were evidently
far separated from each other. _ When the
luxation was reduced, which was effected with-
out much difficulty, crepitus could be felt,
proving the restoration to its place of the
lower fragment of the fibula.

This is a species of fracture and luxation,
which can, by proper management, be readily
redressed, and no deformity remains, if time
be not lost after the accident has occur-
red; but if the fibula become solidly united
in its new situation, the motions of the ankle-
joint are for ever lost, and the patient is doomed
to lameness for life.

In the month of September 1833, a woman,
aged fifty-three years, was admitted into Jervis-
street Hlospital, whose left ankle-joint presented
all the characters above assigned to the partial
dislocation forwards of the tibia, combined with
a simple fracture of the fibula; she stated that —
she had, two months previously, broken her
leg close to the ankle joint, and had been at-
tended at her own house, from a dispensary, by
a pupil, who applied pads and lateral splints,
but when after a time all the splints were re-
moved, she found that her limb was deformed, —
her ankle stiff, her foot rigidly extended, and
pointed downwards, so as to be nearly useless —
to her; as two months had elapsed since the —
accident, before she applied, no promise of
relief could be held out to her. She there-
fore left the hospital, but not before I was
enabled, through the kindness of Mr. Sutton, —
to obtain a cast of the leg and foot, from
which figures 57 and 58 are copied. As I ~

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ABNORMAL CONDITION OF THE ANKLE-JOINT.

Partial luxation forwards of the tibia at
the external ankle, with fracture of the fibula
near the malleolus.

Fig. 57.

Viewed on the external side.

Fig. 58.

Viewed on the internal side.

a, b, semicircular excavation posteriorly, and
ase a of the heel backwards; ¢ prominence
ormed by the tibia projected on the dorsum of the
foot; d displacement of the external malleolus
backwards along with the foot.

was anxious, before these pages went to press,
again to examine this case, I requested Mr. S.
to make inquiry about her; he learned that
the woman died dropsical a few days before,
and with much difficulty procured for me an
Opportunity to examine the limb, which on
careful dissection presented the following ap-
pearances :—the whole extremity was somewhat
wasted, the skin on the sole of the foot was
smooth and fine, shewing that she had been
able to walk but little since the accident; the
foot was in a position of almost rigid extension,
the toes were directed downwards, the range of
motion of flexion and extension did not exceed
one inch, in short, all the usual characters

Si to the partial dislocation forwards of
the tibia and displacement of the foot back-
wards were seen; when the skin was re-
moved from the fascia of the leg and foot,
the intervening cellular membrane was found
infiltrated with serum, the skin was adherent
to the inner malleolus, the vena saphena
and the nerve of the same name were thick-

ened and firmly connected together, the ex-
VOL. I.

161

tensor tendons were stretched over the tibia,
and were somewhat flattened, and the grooves
which transmit the tendons that play behind
the inner and outer malleolus were deepened.
We now directed our attention to the state of
the bones; we found that the tibia was dis-
placed forwards, that its anterior edge was ad-
vanced more than one inch beyond its natural
situation, and that it much overhung the os
naviculare, but such was the direction and state
of obliquity of the tibia with respect to the
foot, that it could not be said to rest upon that
bone; between the os naviculare and the infe-
rior articular extremity of the tibia there inter-
vened much fat of a yellow hue and fibrous
texture, like intervertebral substance ; the inter-
nal malleolus itself had not escaped injury, the
deltoid ligament had not in this instance as in the
former given way ; the internal malleolus itself
had been broken, and a small portion of the back
part of the edge of the articular cavity of the tibia
was detached, and both malleoli were retracted,
or carried backwards with the foot; the fibula
above the fractured portion was directed down-
wards and a little forwards, and was somewhat
parallel to the tibia, yet more than naturally
approximated to it, a circumstance which ac-
counted for the contracted rounded form the
middle of the leg possessed ; the lower frag-

Fig. 59.

Fig. 60,

Viewed on the internal side.

Skeleton preparations of fig. 57 and 58,
M

162

ment of the fibula was directed from below
upwards, a little inwards, and very much for-
wards, so as to make with its shaft a remark-
able angle salient anteriorly; this bone had
been traversed by the fracture obliquely, from
above downwards and from before backwards.
The external malleolus was placed about
one inch and a quarter behind its usual situa-
tion, and was consequently dislocated at its
tibio-fibular articulation, having burst those
strong ligaments which connect these bones
theether, and which are so seldom found to
yield.

Luxation of the bones of the leg backwards
at the ankle-joint —A luxation of one or both
bones of the leg at the ankle-joint backwards,
whether the accident be what has been called
complete or incomplete, whether accompanied
with a fracture of the fibula, or merely with a
rupture of the ligaments, is a displacement
which must be considered exceedingly rare.
Boyer, in his valuable work, gives no case of
it from his own observation ; and in alluding
to such an accident, states that no author, to
his knowledge, has given a single example of
it. Sir A, Cooper evidently has not seen it;
for he says, “ 1 have seen the tibia dislocated
in three different directions, inwards, forwards,
and outwards; and a fourth species of disloca-
tion is said sometimes to occur, viz. back-
wards.” Baron Dupuytren states that he has
never seen this accident.*

Mr. Colles has given me the notes of one
case, and it is the only one he can, in his exten-
sive experience, recollect to have met with, of
a partial dislocation of the lower part of the
tibia and fibula backwards, and has also shewn
me the cast he had taken of the leg. In this
case the tibia seemed thrown partially back-
wards, from the articular pulley of the astraga-
lus; the fibula was unbroken, and was also
carried backwards with the tibia; the foot,
measured from the instep upon its dorsum, was
longer than that of the opposite side, the heel
was shorter and less pointed, the space in front
of the tendo Achillis, near to the os calcis,
was partially filled up, and a hard swelling oc-
cupied the lower and back part of the tibia,
which was evidently formed by a quantity of
callus, which had cemented together the frag-
ments of a fracture of the lowest part of the
na the leg was shorter than the opposite
imb.

It would have been interesting to have learned
the precise manner in which this accident had
occurred; but as to this, or the immediate
symptoms which followed the injury, I could
get no satisfactory information. The man did
not apply to Stevens’s Hospital until the bones
were united in their new and faulty position.
Besides the partial dislocation backwards of the
tibia, this bone with the outer malleolus of the
fibula was inclined somewhat outwards; and
the man walked lame and most awkwardly on

* Je n’ai jamais vu de luxation du pied en avant,
dans les fractures du peroné et de l’extrémité du
tibia.—Annuaire Médico-Chirurgical, 1819, Paris,
p. 159,

ABNORMAL CONDITION OF THE ANKLE-JOINT.

the outer edge of the heel and foot, the inner
side of which was somewhat curved inwards,

I have had occasion to notice a displace-
ment of the tibia backwards on the os calcis,
in a case where the astragalus sloughed in con-
sequence of a compound injury to the external
malleolus and ankle-joint; but such a case is
different from that now under our considera-
tion, although the possibility of such an occur-
rence should not be lost sight of.

2. Morbid anatomy. a. Acute inflammation
of the synovial membrane of the ankle-joint
produces changes in the synovial fluid of the
articulation both in quantity and quality, and
alterations very generally in the appearance and
structure of themembrane; I say very generally,
for I have known an exception to the rule, in a
case * of acute synovitis of the ankle-joint which
caused the death of the patient in fifty hours
from its first onset; during the whole of the
time the patient never slept nor ceased to com-
plain of the agonizing pain of the ankle-joint.
At the post-mortem examination, before the
skin was removed, the extensors of the toes were
observed to be displaced by the fluid which
distended the synovial sac of the articulation,
and fluctuation was now, as during life, to be
felt in two tumours which existed in front of
the two malleoli; the interior of the joint was
occupied by a turbid oily synovial fluid; no
false membrane existed, and if there had been
increased vascularity during life, no trace of it
was discoverable at the time of examination :
increased quantity with altered quality of the
synovial fluid were the only deviations from
the normal condition which could be noticed.
Portions of the synovial membrane are, how-
ever, occasionally found covered with false
membrane. Pus has also been found in
the joint, sometimes laudable, sometimes
fetid, and of a brownish red colour; the
membrane has been found thickened, and has
afforded evidence of increased vascularity, and
even in some points has presented a villous ap-
pearance. In very young subjects I have known
acute inflammation of the ankle-joint in a few
days extend itself to the epiphysis, and produce
separation of it from the shaft of the tibia; and in
such cases a displacement of the shaft inwards,
and of the epiphysis and foot outwards, occurs
from the action of the muscles, as in Pott’s luxa-
tion. Acute inflammation commencing in the
synovial membrane of the ankle-joint sometimes
extends farther than this: there have been cases
in the Richmond Hospital, and the specimens
have been preserved in the museum, of acute
synovitis of the ankle in which the inflammation
extended through the vascular junction of the
epiphysis and shaft of the tibia, and having
occupied the cellular junction of the periosteum
with the anterior and inner surface of the tibia,
soon ended in the formation of pus and lymph,
which detached from the bone its immediate
covering, and produced effects which termi-
nated in the death of the patient. Ihave seen

this detachment of the lower epiphysis of the

tibia in an infant six days old, the result of acute

* See Dublin Journal, vol. iv. p. 1.

ABNORMAL CONDITION OF THE ANKLE-JOINT,

synovitis, with purulent deposition in the joint,
and in a young man aged twenty, but have not
observed it ever to occur in older subjects ; and
conclude that it is one of the consequences
synovitis of the ankle-joint, which is only to be
noticed at an age when the epiphyses are not
yet consolidated with the shaft of the tibia.

In these very acute attacks of inflamma-
tion, its ravages are seldom confined to the
structure which seemed to be the ‘point du
départ’ of the disease; the cartilages are in
some cases removed from the tibia, fibula, and
upper surface of the astragalus with astonishing
rapidity; the porous surface of the bones has
also been found exposed, and their substance
to afford evidence of its having been in a state
of inflammation. Surgeons should ever bear
in mind, that the synovial membrane of the
ankle-joint passes very far forwards on the
upper surface of the astragalus, even as far as
within a few lines of the junction of this bone
with the os naviculare, so that an accidental
wound high upon the instep might very readily
give rise to a fatal synovitis of the ankle-joint.
Moreover, by an experiment on the dead sub-
ject, it may be shown that a very slight direc-
tion too much upwards of the edge of the knife
when the operation of partial amputation, ac-
cording to Clones, is performed, may wound
the most anterior part of the synovial sac of the
ankle-joint, and the consequences of such a
mishap might prove fatal, or at all events
greatly aggravate the ills which even without
such cause too frequently follow Chopart’s
operation.

Again, the synovial membrane extends very
low down, even to the lowest point of the inner
side of the peroneal malleolus, along the outer
or fibular surface of the astragalus (fig. 61, «).

It has very frequently happened to the wri-
ter’s knowledge, that inflammation commencing
in the body of the os calcis, or in the fibrous or
synovial tissue of the articulation between the
0s calcis and under surface of the astragalus, has
crept up to the ankle-joint by this route between
the fibula and astragalus ; when, therefore, opera-
tionsand cauterizations are performed by surgeons
to cure the carious state of the os calcis, the close
contiguity of such an important articulation as
that of the ankle should be recollected. The
great proximity of the ankle-joint to that be-
tween the under surface of the astragalus and
os calcis can only be estimated by making a
vertical section of the tibia, fibula, astragalus,
and os calcis, passing transversely across these
bones and through the malleoli, as may be seen
in fig. 61; and if a subject be selected in which
the epiphysis has not been consolidated with
the rest of the bone, a useful view may be had
illustrating many of the preceding practical
observations, and explaining clearly how in-
flammation, traumatic or idiopathic, once esta-
blished in the ankle-joint, can pass through the
epiphysis to the periosteum of the tibia; and ori-
ginating either in the body of the os calcis, or in
some of the structures composing the articulation
between this bone and the under surface of the
astragalus, can be propagated to the ankle-joint :
such a viewas this will shew thenecessity of con-

163
Fig. 61.

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sidering, in connexion, the normal and abnor-
mal state of these important articulations.

b. Chronic disease.—The effects of chronic
diseases on the tissues composing the ankle-
joint are next to be considered ; these are vari-
ous, and may be referred to the influence of
specific diseases, such as gout, syphilis, struma,
rheumatism, &c.; but the effects of most of these
on this particular articulation need not here be
discussed, as they will be sufficiently dwelt on
elsewhere in this work (see Jornt): we deem it,
however, right to enter somewhat into detail in
the description of those morbid appearances of
the ankle-joint which are supposed to be of a
scrophulous origin, and which are denominated
white swelling of the ankle-joint. The external
characters of the affection are pretty much those
in common with the same melancholy disease,
in whatever articulation of the extremity it is
situated; the swelling, at first soft, and appear-
ing in front of each malleolus, seems divided
into two by the extensor tendons; after a time
it becomes more solid, and assumes somewhat of
a globular form ; here as elsewhere, however, it
does not completely surround the joint. The
limb above is wasted and the heel is retracted ;
the foot is edematous, and the toes are pointed
downwards, no motion of flexion or extension
can be communicated to the foot ; but when the
bones are moved laterally, an unnatural motion
is communicated to the foot, and a grating of
rough and carious surfaces in advanced cases
can be felt: the sides of the swelling are
studded over with numerous fistulous orifices,
from which even now a thin sanious matter can
be pressed ; a probe introduced passes either
directly through one or other of the malleoli,
or by a circuitous route into the interior of
the joint through the sinuses, which are, as

M 2

164

it were, the excretory ducts leading from the
interior, and conducting out the sanious and
sabulous matter which proceed from the dege-
nerated cartilages, synovial membranes, and
bones of the diseased joint. The skin is thin,
soft, and shining, and moveable on the sur-
face, except where the fistulous orifices exist.

The anatomical characters of this disease in
its advanced stage affecting this articulation we
have many opportunities of observing. When
the superficial coverings of the swelling are
removed, the fat is remarked to be consistent
and yellow, the cellular tissue interposed be-
tween the ligaments, tendons, and muscles is
infiltrated with a viscid, semi-fluid, spongy,
homogeneous mass; sometimes this tissue be-
comes so thick, and is so connected with the
lateral ligaments of the ankle-joint, and so in-
terposed among their softened fibres, as to render
a clean dissection of these last impracticable ; so
that the ligamentous and cellular structures
around the joint appear to have undergone a
species of fibro-cartilaginous degeneration ; the
viscid glairy matter infiltrated around the joint
with the tumefied ligaments are the parts which
cause the principal swelling, and give to the fingers
examining it that deceptive feeling of fluctuation
which characterises the white swelling wherever
situated.

The few muscular fibres to be found near this
joint are pale and of a gelatinous appearance,
being infiltrated with the same matter as that
which pervades the more superficial structures.
The tendons, nevertheless, preserve their natural
colour and consistence. ‘The periosteum will
be found much thickened and easily detached
from the bone.

The bones of the joint, and those in its vici-
nity, are very usually more or less atrophied,
and have undergone a process of degeneration ;
notwithstanding, however, what has been said
on high authority to the contrary, these bones
are occasionally enlarged and expanded ; they
have lost much of their specific gravity, their
spongy tissue is softened, yellowish, and easily
penetrated by a knife, and filled with a matter
pare bhing adipocere, or a yellow semi-fluid
at.

The heel it has been noticed is elongated,
and the foot measured from the tibia to the
toes on the dorsum is shortened very generally,
and pointed downwards. Dissection discovers
the cause ofthis frequent phenomenon in a par-
tial dislocation of the tibia forwards on the
astragalus, the softened ligaments allowing the
action of the gastrocnemii and solei to drag
the whole foot backwards. In the interior of
the articulation, a more or less considerable
quantity of a sanious matter is found; while
the cartilages covering the end of the tibia
and fibula, and surfaces of the astragalus, are
softened, adhere but slightly to the bones, and
have been partially removed, leaving exposed
the porous structure of the latter.

The arteries, veins, and capillaries present no
eculiarity, except that the naturally white
igamentous tissue is more freely supplied than

usual with red vessels. The neurilema of the
posterior tibial nerve is evidently much thick-

ANNELIDA.

ened, so as to give it an appearance of enlarge-
ment; the small nerves around the joint seem.

also hypertrophied. ;
ibe (.R. Adams.)

ANNELIDA, (a generally adopted, but
barbarous latinization of the French term
‘ Annélides,’ from ‘ Annellus,’ a little ring;
ought rather to be written ‘ Annulata’or ‘ An-
nellata.’)—The natural group of Annelida
comprehends all the invertebrated animals
which have a soft body divided into transverse
segments or rings; a distinct central nervous
system disposed in the form of a longitudinal
gangliated chord, blood coloured (generally
red), and contained in a system of appropriate
and very distinct vessels; and, lastly, organs of
locomotion, consisting either of fleshy appen-
dages provided with bristles, or of bristles only ; :
or of a prehensile cavity situated at each ex-
tremity of the body; but never of articulated
members, as in the Arachnida, Crustacea, and
Insecta.

The establishment of this class is due to
Cuvier. Prior to him, Pallas, Miiller, and
Otho Fabricius, had made observations of great
interest on the animals of which it is com-
posed; and we find in the writings of the
author of the Miscellanea Zoologica the most
happy ideas respecting the natural relations
which these animals bear to one another.
Nevertheless, these works had at first but little
influence on the classification of the Inverte-
brata, and fora long time naturalists persisted in
following the method of Linnzus, who united
under the term Vermes, the Mollusca, Zoophyta,
and Annelida, and dispersed the latter in three
different sections of that great class; confound-
ing some with the Entozoa (intestinal worms),
others with the Acephalous Mollusca, and others
again with the Testacea.

It was in the work entitled “Tableau Ele-
mentaire de l’Histoire Naturelle des Animaux,”
published in the years 1797-8, that M. Cuvier
laid the first foundation of a natural distribution
of invertebrated animals. He collected together
in the class Vermes the species which more lately
have constituted the groups of Annelida and
Entozoa, and established in it the two divisions
corresponding to those which are generally
adopted at the present day. Having subse-
quently determined the presence of red blood
in the leech, and having investigated the circu-
lating apparatus in these animals, Cuvier sepa-
rated the “ red-blooded” from the “ intestinal”
worms, and constituted for the former a distinct
class, to which Lamarck afterwards gave the
name of “ Annélides,” which has been gene-—
rally adopted, and is used at the present day
by most naturalists.*

This classification being based essentially on —
anatomical structure, has been atop by |
Lamarck, Dumeril, Savigny, Leach, Latreille,

3

* See Cuvier, Bulletin des Sciences par la Société _
Philomathique, an vii. etx. Lamarck, Discours —
d’ouverture du cours des Animaux sans Vertébres —
prononcé en Mai 1806, et Histoire des Animaux sans ~

Vertébres.

EYL eM » Ait te f ~

ANNELIDA. 165

-&c., but is not received by all zoologists of the

present day. M. De Blainville, in his metho-
dical distribution of the animal kingdom, has
adopted another plan. Taking the exterior
organs for the base of his system, this naturalist
divides the articulate animals, which he terms
“ Entomozoaires,” into seven classes, of which
the penultimate, viz., the “ chétopodes,” com-
prehends the Annelidans provided with loco-
motive bristles, and of which the last, viz, the
“‘apodes,” is composed of the Annelidans des-

titute of those organs, together with the planarie
and intestinal worms.*

The general plan of organization exhibited
in the animals which are grouped together by
Cuvier under the name of “ vers intestinaux,”
and the numerous affinities which connect the
planariz and several helmintha to the Annelida,
sppett to us fully to justify a partial adoption
of the innovations introduced by M. De Blain-
ville, and to indicate that the natural position
of the white-blooded worms is by the side of
those with red blood, at the bottom of the sub-
kingdom of articulate animals; whilst in the
system of Cuvier the Annelida are placed at
the head of that great division of the animal
kingdom, and the entozoa are left among the
zoophytes. But, on the other hand, similar
reasons appear to us to oppose the adoption of the
divisions which M. De Blainville has proposed
for the articulate animals. That zoologist, in
fact, establishes a distinction between his che-
topoda and apoda as wide as between the former
and the insecta, arachnida and crustacea, and
thus separates from the setiferous annelidans to
place among the intestinal worms the hirudines,
which approximate to the former and deviate
from the latter in many of the most important
points of their organization ; for example, in the
existence of a gangliated nervous system.

This arrangement does not appear to us to
accord with the spirit of a natural classification,
in which the several divisions ought to be in-
dicative of the different degrees of importance
which the modifications of the animal organiza-
tion present.

In the present state of science the class An-
nelida ought in our opinion to be preserved
nearly as it was established by Cuvier, but
should be joined with the entozoa and rotifera,
to form a great division. of the sub-kingdom
articulata, distinct from the natural group, con-
sisting of insecta, myriapoda, arachnida, and
crustacea. The affinities, indeed, between the
Setiferous annelidans and the hirudines are too
close to admit of their being arranged in sepa-
rate classes ; and, on the other hand, every day
discloses new facts of a nature which demon-
Strate that the vermiform animals pass from
one to another by almost insensible gradations.
Thus the researches of M. Dugeés on the
planarie show how closely their structure ap-
proaches that of certain red-blooded worms, and
the distinction founded on the colour of the
nutritious fluid no longer suffices to separate

* See the Bulletin de la Soc. Philomathique,
1818 ; De l’Organization des Animaux par M. de
Blainville, tom. i. table 7; and the article ‘ Vers’ of
the Dictionnaire des Sciences Naturelles, tom. lvii.

them ; for on the one hand it is proved that

the colour of the blood is yellow and not red

in some of the annelidans properly so called;
while on the other hand I have recently ob-
served on the shores of the Mediterranean an
animal which differs from the genus prostoma
only in the possession of red blood. We now
know intestinal worms which have a circulation
and a vascular system as well formed as that of
the annelida, which they already resemble so
much by their outward form. The absence of
a rudimentary nervous system in the entozoa is
called m question by skilful anatomists. Lastly,
the excellent works of Ehrenberg on the in-
fusoria of the class rotifera prove the analogy
that exists between these minute beings and the
articulate animals generally, but more espe-
cially to the annelida.

The differences which the annelida present
among themselves have necessitated their di-
vision into many secondary groups or orders.
In the latest work* that has been published on
the classification of these animals, they have
been divided into four orders, under the names
of Annelida errantia, Annelida tubicola, Anne-
lida terricola,and Annelida suctoria (suceuses).
This classification is based on the combination
of the modifications which exist in the struc-
ture of these beings, and does not materially
differ from that proposed by M. Cuvier in the
Régne Animal, and by M. Savigny in the
great work on Egypt.

The following is a table of the principal
characters which distinguish these groups.

First Order—ANNELIDA ERRANTIA.

Body, with soft appendages (cirri, branchie,
or antenne), generally disposed over the
whole length of the animal, and not collected
towards the cephalic extremity.

Feet generally very distinct, armed with sete or
bristles, which have very rarely the form of
hooks.

Head generally distinct, and provided with eyes,
antenne, and a retractile proboscis, often
with jaws.

(This order, which nearly corresponds to that

of the Annelida dorsibranchiata of Cuvier, com-

prehends the genera Aphrodita, Polynoé, Polyo-
dontes, Acoetes, Sigalion, Palmyra, Amphinome,

Chloeia, Euphrosyne, Hipponoe, Eunice, Onu-

phis, Diopatra, Lysidice, Lombrinereis, Aglaura,

(Enone, Nereis, Syllis, Hesione, Alciope, Myri-

ana, Phyllodoce, Nephtys, Goninada, Glycera,

Aricia, Aonis, Ophelia, Cirrhatulis, Peripatus,

Chetopterus, Arenicola.)

Second Order.—ANNELIDA TUBICOLA.
Body, with soft appendages, for the most part
collected together at the cephalic extremity.
Feet, almost always of two kinds, generally de-

prived of cirri, and armed with hooked bristles.

Head not distinct, without eyes, antenne, pro
tractile proboscis, or jaws. .

(This order corresponds to that established by

Cuvier under the same name, and includes the

* See Classification des Annelides et description
des espéces qui habitent les cétes de la France,
par MM. Audouin et Milne Edwards, tom. ii.
des Recherches pour servir al’Hist. Nat. du littoral
de la France.

166:

. genera Serpula, Sabella, Terebella, Amphitrite,
Hermella, and Siphostoma.) - |
Third Order.—ANNELIDA TERRICOLA,
Body, completely destitute of soft appendages.
Feet, scarcely or not at all distinguishable, and

represented only by some bristles.

Head not distinct, without eyes, antenne, or
jaws.

This order comprehends the genera Clymena,
Lumbricus, Nais, &c.

In the classification of M. Cuvier it is united
to the Hirudinida to form the order Anne-
lides abranches.

Fourth Order—ANNELIDA SUCTORIA.

- Body destitute of bristles for locomotion, com-
pletely apodous, and without soft appen-
dages. A prehensile cavity in the form of a
sucker at each extremity of the body.

Head, not distinct, but generally provided with
eyes and jaws.

This order is composed of the family of Hiru-

dinida, and of the genus Branchellion.

External conformation.—The Annelida have
always an elongated, generally cylindrical, and
vermicular form; sometimes, however, they
are flat or more or less oval. The body is com-
posed, as we have already observed, of a series
of rings, not of a horny or calcareous texture as
in the majority of insects and crustacea, but
membranous and separated from each other
only by a transverse fold of the integument; as is
seen in certain larve. The number of these rings
is occasionally very considerable (some nereida
have more than 500), and in many annelida it
varies considerably in different individuals of
the same species, and seems to increase with age.
In some instances these segments are sub-
divided into two or more transverse bands by
furrows.

In general each ring supports a pair of mem-
bers, and when an apparently single segment
gives origin to a greater number of these or-
gans, it is easy to perceive that it results from
the union of many rings blended together.
The two extremities of the body are sometimes
dilated in the form of suckers (in the sucterious
annelidans), but in general nothing of the kind
exists, and the anterior extremity either resem-
bles the rest of the body, or it terminates in a
head more or less distinct (as in the nereida,
see fig. 62), often supporting eyes (a), and fili-

Fig. 62.

ANNELIDA.

form appendages called antennz, (b,c), the num-
ber of which is generally three, four, or five. _

~ The mouth is situated at the extremity of the
body, and in the acephalous annelida is di-
rected forwards, but in the cephalous species
this opening is situated below the base of the
head. The anus is placed at the opposite ex-
tremity, and is almost always found on the
dorsal aspect of the body. A certain number
of Annelida are completely apodous, and do
not present the least trace of an appendage on
any of the segments of the body (the hirudinide).
Others exhibit on either side many rows of
bristles, which fulfil the office of feet (the terri-

cole). In others, again, the bristles of which

we have spoken are supported on a fleshy
tubercle more or less prominent, and more or
less complicated in structure, and to these
organs the name of feet is applied.

The feet of the Annelida, when they present
the maximum of development of which they
are susceptible in that class of animals, are com-
posed each of two very distinct portions, placed
one above the other, and appertaining the one te
the dorsal, the other to the ventral arch of the
ring. (See fig. 63,which represents one of the feet

of anamphinome.) M. Savigny, who was the
first to study with due care the zoological cha-
racters furnished by these appendages of the
annelida, gave to these portions of the feet the
names of dorsal oar (a) and ventral oar (b) (rame
dorsal et rame ventral). Sometimes these oars
are pretty distant from one another, (fig. 63.)
sometimes they are separated only by a shallow
fissure (fig. 64. which represents the foot of a
nereid), and occasionally they are so intimately
blended together that they can hardly be dis-

ANNELIDA.

tinguished, and form, as it were, but a single
organ ; lastly, there are cases in which only
one of the oars would seem to be developed.
If one were disposed to compare the loco-
motive system of the annelida with that of the
other articulate classes, the ventral oar should be
regarded as analogous to the members which in
the Crustacea, Insects, &c. are variously modified
to constitute the legs, the jaws, or the antenne :
and the dorsal oar ought to be considered as
representing the appendages, which, though
wanting in the greater number of articulate
animals, yet acquire a considerable develop-
ment on the last two rings of the thoracic
segment of most insects and constitute the
wings. In this particular the annelida afford
an example of the greatest uniformity in the
development of the appendicular system in the
articulate division of the animal kingdom.

Each oar is essentially composed of a fleshy
tubercle more or less prominent, which sup-
ports different productions of the integument,
mcloses the bristles (c), and which is more
especially designated by the name of foot.
Towards the base of the setiferous tubercle
there is generally a membranous appendage,
sometimes filiform, sometimes lamelliform,
called the cirrus (d, e); lastly, it is also above
the margin and near the base of these organs
that the branchie ( f') take their origin, but in
general it is only the dorsal oar that supports
them. All the above parts may exist simul-
taneously, but it often happens that one or
more are atrophied to a greater or less degree,
or are altogether deficient; and this either
along the entire body or on certain segments
only. Thus in the terricolous annelida there
are no cirri; in the hermelle they are pre-
sent on the ventral, but not on the dorsal oar ;
while in the cirrhatule the reverse obtains.

Tn most of the annelida errantia the setiferous
tubercle of both oars is wanting on the first
rings which follow the head, whilst the cirri
assume a very great development, and form the
appendages termed by systematic authors ten-
tacular cirri. ¢ Fig. 62, d.)

A similar modification may be frequently
remarked in the compositiou of the appen-
dicular system of the last ring of the body, and
thence results a certain number of filiform pro-
ductions called styles. Lastly, the antenne of
the annelida, which must not be confounded
with the antennz of insects and crustacea, may
also be considered as representing the cirri of
the dorsal oar of those rings, the union of which
constitutes the head.*

The annelida pass in general a somewhat
Stationary life, and a great number among
them remain constantly buried in the earth or

* For further details regarding the external struc-
ture of the annelida the reader may consult the
excellent work of M. Savigny, intitled “ Systéme
des Annelides,” principally of those found on the
coasts of Egypt and Syria; the article ‘ Vers’ of
the Dictionnaire des Sciences Naturelles, tom. lvii.
by M. De Blainville; and a more recent publica-
tion on the same subject inserted in the Annales
des Sciences Naturelles, tom. xxviii, xxix, and XXX,
and im the second volume of the + Recherches pour
servir a l’Hist. Nat. du littoral de la France, par
MM. Audouin et Milne Edwards.’

167

enclosed in tubes formed by the mucus which

is secreted by the skin, and which, while hard-

ening, commonly agglutinates together frag-

ments of shells and sand. The formation of
these sheaths is very quick. I have seen them

fabricated in the course of a few hours. Some-

times they are of extreme tenuity, occasionally

they are as tough as thick leather, and there

are some which possess very considerable

hardness and are composed in great proportion

of carbonate of lime, like the shells of mol-

lusca. In the greater part of these animals

locomotion is produced by general undulations

of the body determined by contractions of a,
layer of muscular fibres extending from one

ring to another, and fixed to the inner surface

of the skin. But in other species the change

of place is effected by the action of the feet,

of which we have spoken; or by the contrac-
tion of the tentacule which surround the

mouth, as in the terebelle, and which, by

shortening themselves, drag on the body of
the animal in the same manner as the arms of
the cephalopods: lastly, by the action of the

suckers with which the extremities of the body

are furnished.

The bristles ( fig. 63 and 64, c,) with which
the feet of the annelida are provided, do not serve
merely as little levers to facilitate their move-
ments, but are also offensive arms, and their
Structure is very curious. They differ con-
siderably from the hairs of other articulate
animals, which are nothing more than small
tubular prolongations of the epidermic layer.
By their mode of connexion with the integu-
ments and their mode of formation they ap-
pear to approach the hair of mammalia, but
their disposition is of a more complicated na-
ture. They are inclosed in sheaths provided
with muscular fibres, by the aid of which the
animal can protrude and retract them again:
in general, also, they are not merely simple
conical filaments, but their extremity is often
shaped like a harpoon, a lance, or a barbed
arrow, and the annelidan uses it to inflict a
wound upon its enemies.*

Sensation.—Tactile sensibility is considerable
in these animals, and it seems to reside prin-
cipally im the antenne, the cirri, and the
tentacula. They do not appear to possess a
sense of hearing, and there are many among
them which do not manifest any sign of sen-
sibility to light ; but in others, eyes (fig. 62, a,)
exist, the number of which is sometimes very
considerable, but the structure very simple.
They are coloured points, (generally black,) and
situated on the dorsal aspect of the head or on
the cephalic sucker. In the setiferous anne-
lida there are never more than two pairs, but
in the hirudinide or leeches their number
often increases to eight or ten. The anatomy
of these eyes has recently been studied by
Professor Miller of Berlin, and according to
his researches it would seem that these organs
do not contain a crystalline lens, or a trans-
parent body analogous to the vitreous cones of

* See Observations sur les Poils des Annelides
considerés comme moyen de Defense, par MM.
Audouin et Milne Edwards, op. cit. tom. il. p. 31.

168

the crustacea and insecta, but consist simply of
a terminal ganglion of the optic nerve covered
by a layer of black pigment and placed imme-
diately beneath the integument, which is thin and
transparent at that part.*

Nervous system.—In like manner the ner-
vous system of the annelida
is very simple. It occupies
the middle line of the ventral
aspect of the body, and con-
sists of a double series of mi-
nute ganglions of medullary
matter, more or less inti-
mately united or even
blended together, and equal
in number to the number
of rings. (See fig. 65. repre-
senting the nervous system
of the aphrodita aculeata).
The ganglions give origin
to lateral branches, and
are connected together by
two chords of communi-
cation, sometimes separate,
sometimes united into a sin-
gle trunk, so as to constitute a
longitudinal chain extended
through the entire length of
the body. The first of these
ganglions (a) is lodged in the
head, or at least at the ante-
rior extremity of the animal,
in front of or above the di-
gestive tube; the rest are
placed below that canal;
whence it results that the two
nervous chords which form
the media of communi-
cation between the cephalic
ganglion and the first of the
sub-cesophageal series pass
along the sides of the cso-
phagus, and form around that
canal a species of collar or
ring; a character which is common to all the
articulate animals.+

Organs of digestion.—The alimentary canal
in the annelida extends from one end of the
body to the other, and has an external com-
munication at both extremities. The mouth is
generally provided with a projectile proboscis,
which is formed by the anterior portion of the
digestive canal, which can be inverted and pro-
truded like the finger of a glove, and possesses
muscles for the express object of effecting these
movements (see fig. 66, which represents the

s Fig. 66.

Fig. 65.

* See Annales des Sciences Nat. tom. xxii.

+t See Cuvier, Anat. Comparée, tom.i.; Trevi-
ranus, tiber der stachlichten Aphrodite, Zeitschrift
fiir Physiologie, 3 Band; Moquin Tandon, ‘‘ Mo-
nograph. des Hirudinés,” Morrem, ‘* Sur le Lom-
bric,”’ &e,

ANNELIDA.

proboscis of a phyllodoce, and fig. 67, that of a j
nereis). The surface is frequently beset with ;
small papille, and its extremity armed with

Fig. 67.

horny jaws (m), the disposition of which varies
in different genera. It is to be observed that
these jaws are almost always placed laterally
like the mandibles of other articulate animals,
and cannot act upon one another in the direc-
tion of the axis of the body, as in the vertebrata,
but are not to be regarded as analogous to the
mandibles and maxille of insects and crustacea.
In their structure, the jaws of the annelida ap-
proximate rather to the solid plates with which
the interior of the stomach in some crustacea is
provided, and to the hooks which arm the
mouth of certain gasteropodous molluses. This
conformation of the oral apparatus is met
with only in the annelida errantia; in the
annelida terricola there is scarcely a vestige of
a proboscis, and never any teeth or jaws. In
the annelida suctoria, the mouth, which is
placed at the bottom of the cephalic sucker, is
also occasionally protruded in the form ofa
small tubular proboscis, and in other species
its margins are armed with little horny jaws ;
lastly, in the annelida tubicola, nothing of the
kind is to be seen, but in general the superior
border of the mouth forms a sort of projecting
lip, which is provided with long tentacles,
sometimes simple and filiform, sometimes pec-
tinated and resembling tufts. In certain erratic
annelida, the Agliope, for example, there are
also found around the mouth small tentacula,
which are quite distinct from the tentacular
cirri, and which appear to be analogous to the
appendages of which we have just made
mention.

The csophagus which succeeds the pro-
boscis or mouth presents nothing worthy of
notice, but it is in general quite distinct from
the stomach. The conformation of the latter
organ varies much. Sometimes the stomach is
a simple enteroid tube (as in the nereida and
terebelle); sometimes it is composed of two —
pouches, of which the first is membranous —
and may be compared to a crop, while the —
second is muscular and is analogous to a
gizzard, as, for example, in the dumbrici,
thalasseme. In other cases the stomach pre- a
sents on either side a succession of enlarge-
ments which have in general the form of
rounded cells, but which sometimes consti- —
tute saes or vast and much elongated ccecums,
(as in some hirudines, figs. 68 and 69.) Lastly, —

——EEEeE—E—E——e

a
:
|

-ANNELIDA.

we may observe that these coecums are replaced
by blind canals, either simple or ramified ;
thus in the arenicola, or sand worm, we find
that there communicate with the second sto-
mach two ceecums terminated by a soft point,
with thick parietes of a yellow colour; and in
the aphrodite the stomach opens on either side
into a score of membranous appendages, which
commence of very contracted diameter, but
afterwards insensibly become dilated and di-
vide into many branches: (see fig. 70, a, the
retracted probos-
Fig. 70. cis, 6 b, the ap-
ay pendages.) This
a pe of structure
leads tothat which
is manifested in
the planarie, and
also approximates
to what one sees
in the parasitic
arachnida.

The intestine
which succeeds
the stomach is
generally narrow,
and in the majo-
rity of the anne-
lida extends in a
direct line to the

anus. In some
species, as the
amphitrites, it
presents a greater
or less number
of convolutions.
There does not
exist in these
animals a gland
which can be re-
garded as a liver,

. Ke

>
f
\

~e

QsN

169

properly so called: the appendages which are
grouped around the stomach in the arenicole
may, indeed, be biliary vessels analogous to
those of insects rather than true ceca; but in
the earthworms and many other annelides the
bile would seem to be secreted by a peculiar
organ of a yellow colour and pulpy texture,
which surrounds like a sheath a great part of the
digestive canal. Lastly, in certain annelida, as,
for example, the thalassemez, there exists on
either side of the esophagus a small organ,
which would seem to have a secretory office,
and may very probably be a salivary gland.*

Circulation.—The blood in almost all the
annelida differs from that of every other in-
vertebrate animal by its red colour; some-
times, however, this fluid has scarcely a tinge.
According to M. De Blainville the blood of
the aphrodite is yellow, and MM. Mayor and
Gosse, of Geneva, assert that the circulating
fluid of the genus clepsina, one of the hirudi-
nide or leech-tribe, is even altogether white.
When the blood of an annelide is examined
with the microscope it is seen to contain circu-
lar globules, but of a much larger size, and in
far less number than in human blood: it coa-
gulates after rest like the blood of the higher
animals, but it appears to contain a very small
proportion of fibrine.

he blood circulates, as we have already
stated, in peculiar vessels, which its red colour
renders easily distinguishable.

The vascular system has been best studied
in the earthworm: above the alimentary canal
there runs along the entire length of the body
a contractile vessel (fig. 71, a,) which is con-
sequently dorsal, and in which
the blood passes, generally
from behind forwards, some-
times in large waves, some-
times by small quantities pro-
pelled by the successive con-
tractions of the divisions which
this vessel forms through its
entire extent. A portion of the
circulating fluid then passes
into another vessel (c), which
originates at the anterior ex-
tremity of the one above-
mentioned, and which runs
backwards along the ventral
surface of the body below the
nervous column, from which
circumstance it has been cal-
led the sub-nerval vessel by
Dugeés. But the greater part
of the blood which is con-
tained in the dorsal vessel, in-
stead of following this chan-
nel, passes into seven or eight
pairs of large lateral branches
composed each of a series of
dilatations or rounded ve-

Fig. 71.

* See Willis, “De Anima Brutorum;’ Pallas,
‘ Miscellanea Zoologica ;’ Cuvier, ‘ Anat. Comp.’
Treviranus, op. cit. Moquin Tandon, op. cit. 5;
Dugés, op. cit.; Home, ‘ Lectures on Comp,
Anat.” ~

170 ANNELIDA.

sicles , which are highly contractile. These
* moniliform vessels’ are placed in a situation
corresponding to the ovaries: they are directed
downwards and open into a ventral vessel (6),
which occupies the middle line of the inferior
aspect of the animal, following the same track
as the sub-nerval vessel, but situated less
superficially. Its parietes are contractile, and
it may be seen alternately dilating and con-
tracting simultaneously at every part along
the whole of its extent. The blood flows
into this ventral vessel from before backwards,
and leaves it to re-enter the dorsal vessel
by passing through the branches (e) which
ascend perpendicularly to join the latter, on
either side of the alimentary canal, which they
thus embrace, and to which they furnish a great
number of ramifications. The blood con-
tained in the sub-nerval vessel flows equally
from before backwards, and ascends to re-enter
the dorsal vessel by lateral channels (f), ana-
logous to the anastomosing vessels which we have
just described, but situated more superficially
than those. These superficial transverse or
dorso-abdominal vessels, as they are termed by
M. Dugés, severally receive a large branch
from their corresponding deep-seated dorso-
abdominal vessel, and distribute to the skin a
number of ramifications which appear to be
specially destined to bring the blood into
contact with the oxygen necessary for respi-
ration.*

In the genus nats the moniliform vessels,
which in the earthworm perform in some degree
the office of a composite heart, seem to be re-
placed by a single pair of wide veins, which are
contractile and analogous to a divided heart, and
both the superficial and deep-seated transverse
vessels by which the blood ascends to the
dorsal trunk seem to rise from one and the same
ventral trunk; so that the circulatory appa-
ratus is more simple in these annelida than
in the earthworms. The same plan pervades the
sanguiferous system in the other setiferous an-
nelidans, in which the branchiz are distributed
throughout the entire length of the body; but
when these organs are collected together at a
determinate point of the anterior extremity
of the body it is a little different. Thus in
the terebelle the ventral vessel is seen to
bifurcate and to form two lateral branches
which have the form of an arch, and which,
after having passed over the sides of the
cesophagus, re-unite above that tube to form a
single trunk. This trunk reaches the anterior
extremity and gives origin to three pairs of
primary branches, which descend to the vesi-
cular receptacles at the base of the branchie,
and distribute the blood to these organs.

In the leech-tribe the vascular system, on
the contrary, is more complicated, for the san-
guiferous circle is composed of four longitu-
dinal trunks, and the branches which bring
them into communication with each other.
Of the four longitudinal vessels two occupy
the dorsal and ventral aspects of the mesial

* See Dugés, ‘ Recherches sur les Annelides
abranches,’ Annales des Sciences Nat. t. xv.

line, and two the sides of the body. The
dorsal and ventral trunks communicate toge-
ther by dorso-abdominal branches correspond-
ing to each segment of the body. The lateral
trunks also render to the dorsal trunk a series
of dorso-lateral branches, and, moreover, mu-
tually communicate by a series of abdomino-
lateral branches which glide transversely be-
neath the nervous chords. The dorsal and
ventral vessels are evidently analogous to those
which we have designated by the same names
in the earthworm and nais; and the lateral
vessels may be compared to the sub-nerval
trunk of the earthworm, except that, instead
of being single and situated in the mesial line,
they form a circle in which the blood undu-
lates sometimes in one direction, sometimes in
another, but always pursuing an opposite
course in the two canals. Lastly, in addition
to the above ‘ general circulation,’ there is
Observed in the leech-tribe something ana-
logous to the ‘lesser circulation,’ (fig. 72):

Fig. 72.
z

this is effected in the branches (6, e) of the dorso-
lateral vessels (a), which are for the purpose of
bringing the blood into contact with the aerated
water contained in the small membranous
vesicles (f) situated at the sides of each seg-
ment of the animal, and opening externally
upon the inferior aspect.*

Respiration.—F rom what has been said of
the mechanism of the circulation in the annelida,
it will be seen that respiration must be effected
either in the vesicles above mentioned, or on the
surface of the body. Such in fact is the case;
the skin is in general the seat of that function;
but in the greater number of instances, the
integument, instead of maintaining the same
texture throughout, and acting upon the air in
the same manner at every point of its extent,
presents at particular spots peculiar modi-
fications, and thus gives rise to special organs
of respiration called ‘ branchie.’ :

The branchiz of the annelida are almost
universally membranous appendages, highly
vascular, fixed to a certain number of the feet

of the animal, or inserted upon the back near —

the base of these organs.

In the nereida and some other congeneric
annelida, the appendages which are designated
branchiz, and which in fact seem to be in an

“

* See Moquin Tandon, op. cit. ‘Dugés, op. cit.

Se

Eee

ANNELIDA.

especial manner subservient to respiration, are
simply a kind of papillz or laminated cutane-
ous productions very little or not at all sub-
divided, attached either to the extremity or
base of the feet and distributed in an almost
uniform manner over the entire length of the
body, (fig. 64, f,f;,f)) In the eunice, and other
allied genera, their position is the same, but
they assume the form of an elongated filament,
furnished with a series of prolongations of a
similar filiform shape, disposed like the teeth
of a comb, and traversed longitudinally by a
canal filled with red blood, (fig. 73,f-) In
the amphinomian family,
as in the former groups,
these branchiz are placed
on almost every segment
of the body, so that these
organs form along the whole
extent of the back a double
row; but here their struc-
ture is more complicated, for
the filaments are extremely
subdivided, (fig. 63, f.)
In the arenicola, the form
of the branchie is almost
the same as in the amphinomes, but they are
limited in their position to the middle seg-
ments of the y. In the genus terebella
the branchie are also highly ramified vascular
appendages to the integument, but their num-
ber is inconsiderable, and they are all inserted
near the cephalic extremity of the back. In
the serpule, the membrane which forms a
sort of thoracic disc near the cephalic ex-
tremity of the body, ought to be regarded as
an organ of respiration, and it is probable that
the tentacles surrounding the mouth like a
crown of plumes are subservient to the same
function.* In the hirudine respiration is in
part effected by the external skin, but there
exists in these annelida a series of small mem-
branous sacs, which communicate externally
each by a minute orifice situated on the ven-
tral aspect of the body: these sacs derive from
the numerous vessels which ramify upon their

ietes a considerable quantity of blood.

ater penetrates into these organs and seems
to subserve a true respiratory purpose. These
sacs are commonly denominated ‘ pulmonary
sacs,’ and some authors think that they receive
into their interior atmospheric air in a gaseous
form. Their number varies from fifteen to
twenty, and it may be observed, when a living
leech is irritated after being recently removed
from water, that a small quantity of liquid

s from their apertures.

In the lumbrici terrestres there is in like
manner found in each segment and on eitherside
of the digestive tube, an enteroid vessel folded
upon itself, containing a liquid and opening
outwardly by a particular pore. These sacs

Fig. 73.

are less vascular than in the leeches; never-

theless there is reason to believe that they fulfil
am analogous office, and perform a more or less

_* See, for additional details, the works already
cited of Savigny, De Blainville, and Audouin and
Milne Edwards. Sia eh

171

important part in respiration, Lastly, it has
been proved that in the annelida there are
other pores, placed on the back, which tra-
verse directly the dermo-muscular envelope,
and communicate with a cavity intermediate to
the muscles and intestines, and imperfectly
divided by transverse septa, into which air or
water can penetrate. his structure may,
indeed, belong to the respiratory apparatus,

but science does not yet possess sufficient data

to solve that question. An analogous dis-
position has been observed in the nais.*

Generation.— The generative apparatus is
only very imperfectly understood in the anne-
lida. It appears that all these animals are
hermaphrodite, but that they cannot fecundate
themselves ; the intercourse of two individuals
being necessary for the accomplishment of the
act of generation. It is in the earthworm and
leech that this part of their anatomy and phy-
siology has been most completely studied.

In the leeches the sexual apertures are placed
at the inferior surface of the body towards the
anterior third, and separated from one another
by the intervention of five segments. The
anterior aperture belongs to the male organs,
and at the season of reproduction a filiform
and highly contractile penis is observed to be
protruded from that part, (fig. 74, 75, a.)

This communicates in-
ternally with a narrow
cylindrical canal (6),
which in its turn opens
into a kind of whitish
vesicle of a pyriform
shape (c) commonly cal-
led the vesicula semi-
nalis. On each side
of this vesicle there
is an oval whitish body
(d) composed of con-
torted tubes filled with a whitish liquid: each
of these organs is a testicle; and they seve-
rally give origin to a slender vas deferens
(fig. 75, e) of the same colour, which opens
into the vesicula seminalis. Lastly, from the
posterior extremity of the testicle, another fili-
form duct (f) is continued,which passes back-
wards on each side of the nervous cord, and
gives origin to a series of pedunculated vesicles
filled with a whitish fluid similar to that which

* For the structure of the pulmonary sacs, see
Willis, op. cit. Thomas, ‘ Mémoires pour servir
a VHistoire Naturelle des Sangsues.” Home ‘ Lec-
tures on Comp. Anatomy,’ Moquin Tandon, op. cit.
Morren de Lumbric. terrest. . Dugés, op. cit.

172

is contained in the rest of the apparatus.
These organs (fig.74, g) are generally regarded
as accessory vesicles, and they vary both in
number and form in different species.

The female apparatus is of much less mag-
nitude, but also presents a sufficiently com-
plicated structure: it is situated between the
two canals leading to the accessory vesicles of
the male apparatus, and is a little posterior to
the penis. ‘The external orifice, of which we
have already spoken, communicates with a short
canal (fig. 74 and 76, h), of a greyish colour,
which leads to a sort of
pouch (i). This, accord-
ing to some authors,
is analogous to an ute-
rus, but in the opi-
nion of other natura-
lists is merely a copu-
lative vesicle for the pur-
pose of retaining the
fecundating liquid which
is there deposited by
the male in the act of
copulation. This sac is bent upon itself, and
a duct (j) may be observed to be continued
from the anterior extremity which leads to the
ovaries (k): these are small whitish bodies two
in number, and in close approximation to one
another.

In the earthworm, the only parts that can be
regarded as male organs are some sacs or
vesicles varying in number from two to seven,
and situated in a longitudinal series on either
side of the ventral aspect of the body towards
its anterior extremity. Each of these vesicles
adheres to the parietes of the splanchnic cavity,
by a small canal opening directly outwards by
pores placed on the posterior and inferior part
of the corresponding ring: there is farther a
canal of communication, which is continued
directly from one vesicle to another of the
same lateral series; and at the season of co-
pulation there is found in the interior of these
organs a viscid liquid abounding with seminal
microscopic animalcules. The outlets of the
female apparatus occupy the sixteenth segment
of the body, and are continuous internally
with two narrow canals directed forwards, and
Situated on the internal side of the above
mentioned vesicles. Having reached the ova-
ries, each of these canals (fig. 77, a) divides
into two branches (6),
which bend inwards and
terminate by a globular
enlargement (c). This is
seen with the assistance of
the microscope to be itself
formed by a continuation
of the canal puckered u
into numerous folds,which
are enveloped in a com-
mon membrane. To each
of these enlargements are
appended a pair of ova-
ries, the entire number
of which is consequently eight, four on either
side. The colour of these ovaries is whitish,
their texture pulpy, and their interior is beset

ANNELIDA.

with numerous minute vesicles, which are the
ova. At the period of copulation the ovaries
are filled with a whitish fluid, which is pro-
bably the spermatic secretion, but it is not
easy to comprehend how the male apparatus
can introduce it into that part.* According
to Redi, the ova, after being detached from the
oviduct, pass along the whole extent of the
body towards the vicinity of the anus, whence
they are expelled by two orifices stated to be
near the termination of the alimentary canal
or to open in its interior. According to Mon-
tegre it is the foetus and not the ovum which
traverses the body to escape by the above
passages, and the lumbrici according to this
view are viviparous. This statement has been
adopted by many authors without perhaps
sufficient examination; but, according to recent
observations by Dugés, it would seem not to
be correct, and that what have been regarded
as the young of the earthworm are in fact a
species of intestinal worm.

In the nais the male organs are less nume-
rous than in the lumbrici, but differ very little
in other respects. They consist of a single
pair of vesicles opening externally by a wind-
ing canal, which terminates by a small fissure
on the eleventh segment of the body. The
ovaries are disposed in four principal masses,
between which there winds a long oviduct,
of which the extremity can be protruded out-
wardly like a penis.+

In some annelida, as the clepsina carena,
the ova are developed and hatched before
exclusion, so that the young are born alive;
but most of the class are oviparous, and what
is very remarkable, the same ovum sometimes
incloses the germs of many embryos: this is
the case in the earthworm, each ovum of which
produces two individuals, and in the leech the
ova contain severally as many as eighteen
embryos. One might at first view suppose
that the same circumstances obtained in the
nais; but what appears to be an ovum with
multiplied germs is in reality nothing more
than anaggregate of simple ova.

Reproduction.—Some annelida not only per-
petuate the race by the ordinary modes of gene-
ration, but enjoy the singular faculty of pro-
ducing new individuals by a transverse division
of the body. A nais or an earthworm cut in
two and placed under favourable circum-
stances, will continue to live, and each moiety
will become, in appearance at least, a perfect
animal. This fact, which was first determined
by Reaumur and Bonnet, has since heen veri-
fied by M. Duges, Sangiovanni, and many
other observers: the anterior portion of the
animal reproduces a new tail, and the posterior
portion developes a head.

That faculty which the two portions of the
earthworm’s body possess of manifesting the
vital properties independently of one ano-
ther, and even after having been separated,

may be explained to a certain degree by —

the known structure of these animals and

* See Willis, Dugés, &c.
t See Dugés, op. cit.

ANUS.

the general laws of physiology. With the
exception indeed of the generative organs
which are concentrated in a peculiar part of
the body, it is easy to observe that each seg-
ment of the body is almost the exact repe-
tition of all the rest: they all possess the same
organs, and, however the total number of rings
may vary, there results no change of any im-
eee in the general structure of the animal.

ow it may be laid down as a law in phy-
siology, that a parity of organization neces-
sitates a similitude of action; and it results
that as in depriving an earthworm of a given
number of segments no organ is removed of
which it does not still retain the analogue, no
function is completely destroyed ; and conse-
quently that if sucha mutilation should weaken
the vital action, it does not change its nature.
This holds good for both the segments of the
animal: each continues to possess all the
organs essential to individual existence, and
consequently if their resisting energy be suf-
ficiently great, there can be no reason why they
should not continue to live independently of
one another, and become two distinct worms.*
But if the anterior moiety thus becomes a
perfect animal, it is probable that this may
not happen to the posterior portion, but that
the new individual formed by this part will
always continue deprived of generative organs.
For the anterior moiety retains exclusively the
reproductive organs of the original individual,
and there is nothing which authorizes the belief
that the earthworm possesses the power from
being simply mutilated, of reproducing the
whole apparatus on any part of the posterior
moiety. ‘This, however, is a circumstance which
it would be easy to determine.

From the sketch that we have given of the
organization of the annelida, it will be seen
that there exists in this branch of zoology many
hiatuses. Anatomists, in fact, have hardly
paid attention to any but the leech, the earth-
worm, and the nais, and we possess only a
vague notion of the internal structure and
physiology of the erratic and tubicolar species;

eir comparative study would form an interest-
ing subject of research.

BIBLIOGRAPHY.—Cuvier, Anat. Comparée, t. i.
—Bulletin des Sciences par la Société Philoma-
thique, an vii. et x. Lamarck, Discours d’ouver-
ture du cours des animaux sans vertébres, pro-
noncé en Mai 1806, et Histoire des animaux sans
vertébres. Bainville, De organization des ani-
Maux, t. i. tab. 7.—Dictionnaire des Sciences
Naturelles, art. Vers, t. lvii. Audouin & Milne
Edwards, Recherches pour servir a |’histoire natu-
relle du littoral de la France, t.ii. Muguin Tandon,
Monograph. des Hirudinés, 4to. Montp. 1827.
Morrem, De lumbrici terrest. hist. nat. 4to. Bruss.
1829. Pallas, Miscellanea Zoologica, 4to. Lugd.
Bat. 1775. Home, Lectures on Comp. Anat. Duges,
Annales des Sc. Nat. t. xv. Thomas, Mémoires
ro servir a l’histoire nat. des sangsues, 8vo. Paris,

806. Miiller, Vermium terrestrium et fluviatilium,
&c. historia, 2 parts, 8vo. Copenhag. and Lips.
1773-74; Ejus, Von Wiirmern des siissen und
salzigen Wassers, 4to. Kopenhag. 1771; Ej. Zoo-

+ See the article Organisation of the ‘ Dictionaire
Classique d’Histoire Naturelle,’ and the Intro-
duction to my ‘ Elemens de Zoologie.’

173

logia Danica, fol. Copenh. 1788-1806. Schweigger,
Handb. d. Naturgeschichte d. skeletlosen ungeglie-
derten Thieren, 8vo. Leipz. 1820. Weller, Circa
animalium quedam classium inferiorum' incremen-
tum et vitam, 8vo. Halle, 1817. Klein, Descript.
Tubulorum marinorum, 4to. Danz. 1777. Otto, De
Sternapside et Liphostomate diplochaito, vermibus
duobus marinis, 4to. Bresl. 1820. Leo, De struc.
tura lumbrici terrestris, 4to. Regiom. 1820. Clesius,
Beschreibung d. medicinischen Blutigels, 8vo.
Hadamar, 1812. Kuntzmann, Anat.-Physiol. un-
tersuchung tiber d. Blutigel, 8vo. Berl. 1817. Knolz,
Naturhist. Abhandlung uber d. Blutegel, 8vo. Wien.
1820. Johnson, A treatise on the medicinal leech,
8vo. Lond. 1816—Further Obs. on the leech, 8vo.
Lond. 1820. Poupart, Anat. Hist. of the leech from
Journ. des Sgavans 1697, Phil. Trans. 1697. Mo-
rand, Anatomie de la Sangsue: Mem. de Paris,
1739. Bebiena, De Hirudine sermones quinque :
Comment. Bonon. t. 7. Cuvier, Sur les vaissaux
Sanguins des sang-sues: Soc. Philom. An 7,
Wichmann, Vom Girtel des Regenwurms : Beschaft.
der Gesells. Naturforsch. Bd 3. Chamisso, De ani-
malibus e classe Vermium in circumnavig. terrz
observatis, 4to. Berol. 1819. Delle Chiaje, Mem.
sulla storia degli animali senza vertebre del regno
di Napoli, 4 vol. 4to. Nap. 1823-29. Derheims, Hist.
Nat. des Sangsues, 8vo. Paris, 1825. Nicolai, Diss.
de structura lumbrici terrestris, 4to. Berl. 1820.
Olivi, Zoologia Adriatica, 4to. Bassano, 1792. Sorg,
Circa respirationem insectorum et vermium, ]2mo.
Rudolst. 1805. Savigny, Mém. sur les animaux
sans vertébres, 8vo. Paris, 1816; Kjus, Systéme
des annelides, dans le grand ouvr. sur |’Egypte,

fol. Paris.
(H. Milne Edwards. )

ANUS, (in anatomy,) from Anus vel An-
nus, a round, a circle, (syn. ostium recti,
poder, culus. Gr. mgwxros. Fr. anus. Germ.
After. Ital. ano.) is a term commonly applied
to the lower extremity of the rectum : properly
speaking, it is the inferior orifice of the
alimentary tube, through which, in the higher
orders of animals, the excrementitious portion
of the food, as also the excretions from the di-
gestive apparatus, are discharged ; for obvious
reasons it is endowed with powers to assist in
expelling, as also with the faculty of retain-
ing these for a considerable time : such oppo-
site but important qualities would infer the
existence of a somewhat complicated muscular
apparatus, more or less under the influence of
the will, as also a structure in other respects
worthy of attention.

The presence of an anus indicates a complex
system of digestive organs ; hence in many of
the inferior or simpler classes of the invertebrate
division of animals it is absent, and in many
of the superior of this division, as well as in
several of the vertebrata, it presents considerable
variety as to structure, function, and position.
In some of the zoophytes, such as the in-
fusory animalcules there is no central digestive
cavity, and of course no distinct outlet. In them
absorption takes place by imbibition through
pores into cells, in a manner somewhat similar
to a sponge ; and most probably excretion (if any
occurs) takes place through the same orifices.
In others of this class, such as the acalephe,
where a rudimental cavity appears in the body
of the animal, a single orifice admits the food
necessary for its support, and the excremen-
titious portion (if any) is ejected through the
same opening. In the actiniz, also, where a

~~

174

distinct stomach exists, and where the retained
matter obviously undergoes certain changes,
the one orifice serves the two-fold purpose
of admission to the food, as well as of exit to
its residuum. Even in some of the echino-
dermata, as the asteriz, in which the digestive
apparatus is more developed, the central cavity
becoming more complex, the latter is still but
a cul de sac, which can be protruded at the
mouth, the only orifice it presents. In other
species, however, of this m the anus ap-
pears; thus in the English echinus, where the
masticating apparatus is so remarkable, this
Opening exists on the surface of the animal,
Opposite to the mouth.*

In the sipunculi the anus opens near the
mouth, and in the holothuriz near the respira-
tory organ.+

In the several families of the articulata, viz.
Insecta, crustacea, and vermes, the anus exists,
and is always found at that end of the animal
opposite to the mouth, and most generally on
its inferior surface.

In the mollusca it is also present, but it
holds situations singularly differing in the
different orders and genera of this class; thus
in the cephalopoda, as the cuttle-fish, the
rectum opens into a sort of cloaca, which is
situated before the neck, and which also re-
ceives the semen and ova, as well as the
secretion from the ink-bag. In the gastero-
poda, as the slug, it is generally found near
the pulmonary cavity. In the patella or
limpet, however, it opens on the head, and
in the doris on the back, surrounded by a
delicate fringe, a sort of branchial tuft. In
most of the acephala, except the oyster, the
rectum extends along the back of the animal,
beneath the hinge, and above the respiratory
organs; it then passes through the heart, and
opens above the posterior muscle of the shells,
into the cavity of the maulle, or between its
edges, the anal opening presenting the appear-
ance of a fleshy disc or sphincter. |

Among fishes the anus varies, in the osseous
and cartilaginous divisions of this class ; in the
former it usually presents the appearance of
a round opening leading into a longitudinal
groove ; itis placed in front of the anal fin, and
of the urinary and genital aperture, contrary
to what occurs in all other vertebral animals.
In the cartilaginous fish, as the ray and shark,
this groove is deeper, and has the appearance
of a true cloaca, through which are discharged,
as in the sepi and in birds, not only the alvine,
but also the urinal and seminal excretions.

In reptiles the anus serves as the opening
of a cloaca, or common receptacle of the re-
siduum of the food, as well as of the urine,
semen, or ova; in the batrachia, as the frog,
it is situated at the end of the back, and there-
fore above the body of the animal. In the
chelonia, as the tortoise, it is under the tail.
In the sauria and ophidia it is a transverse cleft,
but in the salamander it is a longitudinal fissure
with two prominent lips.

* Home’s Lect. on Comp, Anat. vol. ii. p. 76.
+ Cnvier’s Comp. Anat, t. iv. p. 143.

ANUS.

In birds the rectum expands above the anus
into the cloaca, which also receives the ter-
minations of the ureters, the ends of the vasa
deferentia, and the penis (when the latter
exists); also the openings of the oviducts, and
of the bursa Fabricii. In all the mammalia
the rectum terminates in a distinct anal open-
ing, which is placed at the posterior or in-
ferior extremity of the trunk, directly under
the origin of the tail, and usually in a direc-
tion opposite to the mouth, and in all it is
placed behind, and not, as in fish, before the
urinary and sexual orifice ; in some few of the
quadrumana, as the mandril, it is directed
upwards. In almost all mammalia it is a dis-
tinct orifice, giving passage to the feces only ;
in the beaver and sloth, however, the rectum
and urethra have a common termination. The
monotrematous animals also, such as _ the
echidni and ornithorhynci, form a complete ex-
ception to this statement; in these singular
and anomalous creatures a single opening gives
exit to the fecal and urinary secretions, and
also subserves sexual purposes. (See InrEs-
TINAL CANAL.)

ANUS (in human anatomy). In the present
article we propose to examine not merely the
structures which immediately bound this open-
ing in man, in their normal and healthy state, as
well as in their abnormal and diseased condi-
tions, but we shall also examine the parts which
enclose and surround it, and which can exert an
influence, direct or indirect, on its functions ;
that is, we shall consider the anatomy, normal
and abnormal, of the parts contained in the
Anal Region.

The Anal Region is synonymous with the
posterior portion of the perinzeum ; its triangular
area is denoted by the following outlines: the
apex, which is posterior and superior, is marked
by the extremity of the os coccygis; its base,
which is before and below the latter, is defined
by an imaginary line extending transversely
from one tuber ischii to the other, and each
side is denoted by aline drawn from the last
named process to the point of the coccyx:
these lateral boundaries correspond to the mar-
gins of the glutei maximi muscles, which over-
lap the inferior or the great sacro-sciatic liga-
ments; the base or the transverse line before
mentioned, separates the anal from the anterior
perineal or urethral region: in the adult male
this line will be found to be about three inches,
or nearly three inches and a quarter in length ;
in the female it is about half an inch longer,
and more certainly so if the individual ex-
amined have borne children; great variety, how-
ever, has been found to exist in this measure-
ment, the extremes of which may be stated at
two and four inches. In children under twelve
years of age this transverse diameter of the
perineum is considerably less, in consequence
of the extreme narrowness of the pelvis prior to

uberty.

The anal region contains the lower portion
of the intestinum rectum, several muscles, and
fasci, some nerves and vessels of importance,
and an abundance of adipose substance. The

ANUS.

quantity and consistence of the adipose substance
found in this region vary considerably in dif-
ferent individuals at the several periods of life,
and under various conditions of health ; a fact
most important for the surgeon to bear in mind,
inasmuch as this diversity causes corresponding
differences in the physical characters which this
region presents under these particular circum-
stances. In children, and in the female, in youth
and middle age, as also in the robust and
healthy male, this region will be found plump,
or convex around the anus, whereas in the ema-
ciated, the sickly, or the old, it gig presents ape
very opposite appearances; and a proportiona
diference may ie observed in the depth of the
perineum, or in the distance between the neck
of the bladder and the surface: the greatest
extremes of this difference have been found
between two and four inches, a circumstance
which bears materially on the lateral operation
of lithotomy.

So much of the Rectum as lies beneath the
cul de sac of the peritoneum, may be consi-
dered as appertaining to the anal region, and
must, therefore, be noticed at present; below
the reflection of that membrane, this intestine
descends obliquely forwards between the sacrum
and bladder, in the male as far as the prostate
gland, and in the female as far as the vagina;
it is there on a level with the inferior extremity
of the coccyx, and then it bends downwards
and backwards, and ends in the anal opening ;
the perineal portion of the Rectum, therefore,
is convex forwards and concave towards the
coecyx ; hence in introducing into this intestine
the bougie, enema pipe, or even the finger, it
should be directed at first upwards, and for-
wards, and then upwards and backwards: in
the child, however, this precaution is not ne-
cessary, as the course of this intestine ts not so
much curved, the name of Rectum being then
more correctly applied than in the adult.

_ In order to examine the several parts con-
tained in the anal region, the thighs should be
fully separated, flexed, and fixed on the pelvis ;
the first object which attracts attention is the
Anus.

_ This opening is situated in the median line,
at the bottom as it were of a deep excavation,
which is bounded on either side by the tube-
rosity of the ischium, with the superincumbent
muscular and adipose substance ; in the erect
position it appears at a great depth from the
Surface, in consequence of the approximation
of the nates. In the adult the anus is from one
inch to an inch and a half distant from the

‘point of the coccyx, and three inches from the

arch of the pubis; it is in some measure, but
not perfectly, fixed in its situation, anteriorly
by an indirect attachment to the interosseous
or triangular ligament of the urethra, and pos-
teriorly by a dense fibrous tissue, which forms
a sort of raphé between it and the coccyx, and
to which the muscles and integuments adhere.
In the natural and healthy state, the anus pre-
sents the a ce of a small rounded, or
rather elliptical orifice, whose border is thrown
into numerous small plaits, or ruge, which
during the extended state of the opening are

175

effaced ; these rugz are occasionally so deep as
to admit of the escape of a small quantity of
fluid. As the skin approaches the margin of
this opening it becomes very fine and delicate,
is gathered into those several radiated folds or
plaits, which sink into it, and in the same man-
ner as at the other outlets of the body, it be-
comes continuous with the lining mucous mem-
brane of the intestine, there being no exact line
of demarcation, except that of an increased
vascularity, to distinguish the one from the other.
This plaited condition of the skin which lines
this opening arises from the close contraction
of the subjacent muscle, and is doubtless de-
signed to admit of the more easy dilatability
of the anus during defcecation; this opening,
however, is never equal to the diameter of the
rectum at a little distance above it. In the
child the integument surrounding the anus is
smooth and red, in the adult it is of a dee
brown colour and studded with several fine
hairs, which, however, are usually absent in the
female. In this situation also the cutaneous
follicles are very distinct and numerous, but
not so prominent as in the scrotum ; they secrete
a mucous or sebaceous matter which gives to
the skin a shining or oily appearance, and
adapts it to the functions of the part: from the
absence or from the vitiated condition of this
secretion, painful and troublesome excoriations
not unfrequently ensue. In the healthly state
the margin of the anus feels firm and resisting,
and together with the surrounding muscles
forms a floor or support to the inferior part of
the pelvis, in the centre of which floor the
rectum and its contents are maintained, and
on either side a mass of cellular and adipose
substance.

Muscles.—The muscular apparatus connected
with the lower extremity of the rectum consists
of the superficial and the deep sphincters of
the anus, also the right and left levatores ani,
to which may be added the two transversi
perin@i, and the two coccygai muscles.

The first two, namely, the sphincter muscles,
surround the anus, and may be regarded as a
modification, or as a particular development of
the general circular muscular tunic, which is
continued around the whole alimentary tube
from the mouth to the anus, and which in dif-
ferent situations exhibits a considerable increase
in colour and consistence, for example, in the
lips, around the fauces, the csophagus, the
pylorus, &c. The name of these muscles in-
dicates their principal function, while the other
muscles which have been alluded to proceed from
certain fixed points to be inserted into the lower
extremity of the rectum, and must, therefore,
rather serve to retain the anus in its situation
or to restore it to its natural condition, when
in the exercise of its functions it has been con-
siderably dilated, or slightly displaced by the
expulsive efforts of the diaphragm and abdo-.
minal muscles. We shall first examine the
descriptive anatomy of these individual muscles,
and then consider their several powers or pur-
poses in the economy of the surrounding organs.
Although there are two sphincter muscles of the
anus, yet this name is generally applied to the -

176

more superficial of these; we shall distinguish
these muscles by the names of sphincter ani
cutaneus vel ellipticus, and sphincter ani pro-
Jundus vel orbicularis.

Sphincter ani cutaneus (eQvyyw, constringo,)
coccygeo-anal, sphincter externus, constrictor
ani) is the first muscle which meets the eye of
the anatomist in the dissection of this region.
It may be exposed by dividing the integuments
from the coccyx to near the back part of the
anus, and thence extending an incision on each
side, and about half an inch distant from the
edge of this opening to its forepart, whence it
should be continued indefinitely along the me-
dian line of the perineum; the integument
should then be carefully dissected off from either
side of this elliptical incision.

The muscle thus exposed is thin and flat, of
an elongated and elliptical form, and cleft in the
centre to embrace the opening of the anus; it
arises posteriorly fleshy and cellular from the
point of the coccyx, and from a tense fibrous
or cellular tissue, called the recto-coccygeal liga-
ment, which extends from the coccyx to the
back part of the anus, where it divides and is
lost in the cellular tissue on either side. From
this origin the fibres of the sphincter collect
into a rounded fasciculus, which proceeds for-
wards and downwards, increasing in size, and at
the back of the anus divides into two bands
which pass one on either side of this opening,
each spreading out till it is an inch or even
more in breadth ; again converging in front of
the anus, these bands unite into a fasciculus,
which in the male is very long and passes for-
wards and upwards between the skin and the
acceleratores urine muscles, to be partly in-
serted into the median line of the superficial
fascia of the perineum, and partly confounded
and interlaced with the transversi perinei, and
with the muscles which cover the bulb of the

urethra; through the medium of these last
it is even attached to the common cellulo-
tendinous central point of the perineum, be-
tween the rectum and the bulb, whereby it
is enabled to act on this part of the urinary
canal. This anterior insertion is very variable
in different persons ; in some it stops abruptly
at the bulb, while in others it continues to run
forwards between the skin and the acceleratores
as far as the dartos, in which it terminates. In
the female this anterior fasciculus is much
shorter, and ends in the sphincter or con-
strictor vagine ; in the male its attachment to
the muscles of the bulb is often deficient, so
that in the course of the dissection, when the
superficial fascia has been removed, this ex-
tremity of the muscle will be found detached
and its insertion isolated. The entire of the
inferior surface of this muscle is in contact with
the integuments, its superior surface is related
to the levatores ani, acceleratores urine, and
transversi perinei muscles; in front of the
anus it is confounded with the two latter, and
immediately behind it with the formerly named
muscles ; its external border is of uncertain ex-
tent, and is imbedded in adeps, while its inter-
nal edge is in close relation with the delicate
inflected anal skin, being separated only bya

ANUS.

fine cellular tissue. This muscle is composed
entirely of fleshy fibres, occasionally intersected
by cellular and imperfect tendinous bands;
these fibres are placed in concentric arches,
those of opposite sides unite at acute angles,
and sometimes interlace before and behind the
anus ; the fasciculi are frequently separated by
considerable intervals, so that they appear like
different muscles ; some of the internal fibres
assume a circular arrangement; in the female
this muscle is shorter, broader, and more
rounded, particularly in front. In structure
and appearance this muscle presents great
diversity ; in some it is red, strong, and large,
in others, so pale and weak as to be difficult of
perfect demonstration ; it is also probable that
during life great differences exist as to its
power of contraction.

The use of this muscle is obviously to close
the anus, the skin of which it throws into small
ruge ; hence when the sphincter is paralysed,
there is incontinence of the contents of the rec-
tum ; the most internal fibres will tend to close
the opening more perfectly than the external or
elliptical, which will reduce it rather to a cleft
or fissure; this muscle can also raise the anus
somewhat, and at the same time draw back and
compress the bulb of the urethra; it will also
express the secretion from the anal glands and
follicles. The sphincter ani may be properly
said to belong to the class of mixed muscles,
both as relates to its structure and function ; as
to the former, its paleness, scattered fibres,
connection with the commencement of the mu-
cous surface, and absence of true tendon ally it
to the muscular system of organic life; while on
the other hand the parallel direction of its fas-
ciculi, and the arrangement of many of the
latter in the surrounding adeps, assimilate it to
the muscles of voluntary motion. In its functions
also it appears to border on the province of each
division of the muscular system; thus without
the efforts of the will, or even without any in-
ternal cognizance, it continues in a state of al-
most permanent contraction, and as uncon-
sciously relaxes when the functions of the part
impress upon its sensibility the necessity of so
doing ; while on the other hand the will can
exert a considerable control over its powers,
and can cause it to contract with considerable
and continued energy, as well as throw it into.
a state of atony and relaxation. Although this
muscle belongs to the same class with the other
sphincters, the orbiculares oris and palpebra-
rum, yet it manifests a considerable difference in:
its vitality. The natural and, therefore, the usual —
condition of these other sphincters is relaxation ;
hence the mouth continues open, and partly
from the same cause too, the eyelids are apart; —
whereas the natural condition of the sphincter —
ani when at rest is contraction, and hence the —
anal opening is always closed, although the —
muscle is still capable of contracting with con-
siderably more energy when any of the contents —
of the rectum suddenly approach the orifice, —
or when any irritation exists in its vicinity. -

The Sphincter ani internus vel orbicularis’
(Sphincter intestinale, Winsl.) is of much less —

extent than the former, and is situated more

ANUS.

deeply ; it is closely connected to the mucous
membrane, or the fine lining integument, and
appears a particular development of the circular
fibres of the intestine, like those which surround
the pyloric extremity of the stomach. This cir-
cular muscular ring consists of several fine and
pale fasciculi of fibres, which are closely con-
nected together, and when contracted form a
thick ring around the intestine immediately with-
inthe anus; this muscle may be exposed either
by detaching the lining membrane which is but
loosely attached to it, or removing the rectum
from the subject, everting and distending it.
The mucous membrane being then detached,
the muscle will be distinct ; its upper border
is continuous with the circular fibres of the
rectum, and a distinct cellular line separates it
from the cutaneous sphincter; anteriorly it is
connected with the levatores ani muscles.

The action of this muscle must be to assist
the former sphincter in closing the lower ex-
tremity of the rectum and supporting its con-
tents; in the process of defecation it assists in
the expulsion of the residual portions of the
fecal matter, by the sudden or almost spas-
modic action which succeeds its relaxation ;
moreover, it strongly opposes the entrance of
any foreign body by the anus; so that from
its power of resisting the ingress or egress of any
substance, it may be considered as constituting
a perfect pylorus.

The subcutaneous adipose tissue in perineo
is very abundant in some situations; close to
the anus, or between the sphincter and the
skin, there is but very little; hence abscesses
but seldom form there, except of very limited
size, such as small furunculi, or as the result of
circumscribed inflammation in some of the fol-
licles around the opening; whereas at either
side of the anus and rectum there always exists
a considerable quantity of cellular and adipose
matter, the former remarkable for the large
size of its cells, which are intersected by irre-
gular bands or fibres from the perinzal fascia,
_ and which give the whole some degree of
elasticity ; the adipose substance is abundant,
very soft, loose, sometimes reddish, and fills
those large spaces which exist on either side of
_ the rectum. In no part of the body do ab-

_ Scesses so frequently form as in these ischio-
rectal i and as such abscesses are very
|‘ generally attended with consequences tedious,

_ troublesome, and dangerous, it may be right
_ to make a few remarks on the anatomy of
_ these regions.

__ Each Ischio-rectal space is a deep triangular
hollow, the base being situated towards the
_ integuments, the apex towards the cavity of
_ the pelvis; the outer side is formed by the
_ ischium, and the inner by the rectum with
' its muscles; this intestine, together with the

_ attachments of the levatores ani behind and
oe » Separates the two on from each
‘ other, but the cellular membrane of one side
_ €ommunicates with that of the opposite, and
. hence in cases of diffused or extensive suppu-
_ fations, the fluid is occasionally observed to
* _ from one side to the other; anteriorly
_ the transversus perinei, and posteriorly the
| VOL. I.

177

coccygeus muscles bound this hollow. Each
of these triangular recesses is lined on all sides,.
except towards the skin, by fascie, a view of
which may be obtained by dissecting out of
either all the contained adeps. There may

then be observed near the apex, or the deepest

part of the recess, a strong and tense aponeu-

rotic line, which is the inferior folded surface

of the pelvic fascia, which in this situation

sends off its inferior or descending layer;

this latter immediately divides into two lamina,

an internal and an external; the latter is called

the obturator, the former the ischio-rectal fascia ;

the former is very strong and distinct, the latter

very thin and cellular.

The obturator fascia descends a little ob-
liquely outwards and is inserted into the falci-
form process of the great sacro-sciatic liga-
ment, and into the tuberosity and ramus of the
ischium. It is very dense, being composed of
strong aponeurotic fibres, and it conceals and
separates from the perineum the obturator in-
ternus muscle, and the internal pudic nerves
and vessels, the perineal and hemorrhoidal
branches of which pierce it as they proceed
to their destination. The internal layer, or the
Ishio-rectal fascia, is much weaker and more
cellular than the last; from the before-men-
tioned aponeurotic line it descends obliquely
inwards along the lower and outer surface
of the levator ani as far as the sphincter, when
it becomes thin and cellular, and is lost in the
surrounding adipose tissue. Thus, by the
unfolding or division of the inferior layer of
the pelvic fascia into these two lamine, the
obturator and ischio-rectal fascie, these re-
cesses are completely lined, and by the gradual
degeneration of the last named aponeurosis
into cellular and fibrous bands, which inter-
lace in every direction, the large mass of adi-
pose substance is enclosed and supported, whilst
a general firmness and elasticity is imparted
to the whole region. Towards the posterior
part of each of these regions a cul de sac is
enclosed between these fascize and overlapped
by the gluteus maximus, on the surface of
which the fascize become extended, and ulti-
mately lost. A somewhat similar but smaller
cul de sac exists anteriorly behind each trans-
versus perinei muscle. An inspection of the
Ischio-rectal spaces will serve to explain not
only the great size to which abscesses here
attain, but also the difficulty in effecting a cure
when they have been of long standing and of
considerable magnitude ; the constantly-vary-
ing form of the rectum on one side, the im-
moveable surface of the pelvis on the opposite,
a muscle above, and the integuments below,
all tend to prevent the possibility of effecting
any permanent apposition between the sides of
the cavity, while very generally the state of the
constitution is equally unfavourable to any
healthy action in the part. These several facts
have impressed surgeons with the propriety of
opening all such abscesses in a very early
stage, otherwise a large cavity will be formed,
the rectum denuded, and very frequently
opened by ulceration. . 4

Transversi perinei muscles ( Ischio-peri-

N

178

neul).—This pair of small muscles extends
in a direction nearly parallel to the ante-
rior border of the anal region; each arises
from the inside of the tuber ischii, passes
inwards, forwards, and downwards to join its
fellow in the median line of the perineum,
where it is also partially attached to the cuta-
neous sphincter of the anus, and to the acce-
leratores urine muscles, or in the female to the
constrictor vagine. These muscles are very
unequal in appearance in different subjects ;
in some they are feeble and indistinct, in others
very strong, and sometimes divided into two
on one or both sides, the additional or minor
muscle being superior and anterior. In the
female these muscles are often found more dis-
tinct than in the male, but even here much
variety exists; in many subjects they appear
to be simply composed of some of the anterior
and partially detached fibres of the middle
portions of the levatores ani muscles. The
transversi perinei muscles form the bases of
the two lateral triangular regions contained in
the anterior or urethral perineum, and one
of them, the left, is necessarily divided in
the lateral operation for lithotomy; they are
surrounded by much adipose matter ; two arte-
ries, both branches of the internal pudic, take
a course parallel to them, — viz., the super-
ficial transverse perineal, and the deep trans-
verse, or the artery of the bulb. These muscles
are enveloped between the layers of the perinzal
fascie. The superficial layer, which is continu-
ous with the Ischio-rectal, covers them in their
course forwards to the urethral muscles, and
the deep layer, or the triangular ligament of
the urethra, which is continuous with the ex-
ternal or Ischiatic layer or obturator fascia, lies
between them and the pelvis. These muscles,
therefore, will have the effect of making tense
the different perineal aponeuroses, and thus
they can support, strengthen, and compress
generally the parts in the perineum ; they can
also compress, and thus assist in clearing the
orifice of the anus, at the same time that they
draw back and raise this part, somewhat in
the same manner as the levatores ani muscles.
According to some anatomists these muscles
are considered as dilators of the bulb of the
urethra, as well as of the vagina ; but it is more
than doubtful whether they can exert any such
action. When these muscles are divided, the
base of the deep perinzal fascia, or triangular
ligament of the urethra, is exposed. This will
be observed to have some influence in main-
taining the rectum and anus in their situation ;
its posterior border, being attached to the
levatores ani muscles, and to the bulb of the
urethra, serves to maintain a close connection
between these parts, which is still further ef-
fected by the interlacement of the muscles of
the anus with those which cover the bulb.
(See PERIN£UM.)

Levatores ani (sous-pubio-coccygien ). —This
pair of broad, thin, flat, and nearly square
muscles form a septum somewhat broader
above than below, between the pelvis and
perineum, which, together with the aponeu-
roses covering its upper and lower surfaces,

ANUS.

and with the coccygeal muscles and the trian-
gular ligament of the urethra, completely in-
tercepts all communication between these two
regions except through the natural passages
for the urethra, vagina, and rectum. Although
these muscles are described as two, there ap-
pears no good reason for the division, for the
fibres of opposite sides have a common in-
sertion, partly into the circumference of the
rectum and partly into a middle cellulo-ten-
dinous raphé before and behind that intestine.
lt appears more correct to consider these muscles
as one circular muscular septum extended across
and within the lower opening of the pelvis,
concave towards this cavity, and convex to-
wards the perineum. ‘The fibres attached by
their circumference to the interior of the pelvis,
and converging thence towards the median line
of the perineum, are inserted into and around
the rectum ; in fact the muscle resembles the
diaphragm in form, in the circumference being
its origin or fixed attachment, and the central
portion being its insertion, also in its being
perforated for the transmission of certain parts ; |
the analogy only fails in the absence of a
central tendon, and in the fibres being prin- .
cipally inserted into the parts passing through
it. The fact, however, of there being an inter- :
ruption in the origin of this muscle in the :
middle line both before and behind, in which
respect again there is a resemblance to the
sternal and vertebral deficiences in the dia- ?
phragm, is the cause of its being described as"
consisting of a right and left muscle, which dis-
tinction, it should be observed, is only an
artificial one, for during life the fibres of both ;
sides act together, and in all respects constitute
but a single muscle.

The origin of the levator ani muscle may be
exposed by tearing the peritoneum from the
parietes of the pelvis, together with a con-
siderable quantity of loose cellulo-adipose
membrane. The recto-vesical layer of the pel-
vic fascia should then be divided near to the
neck and sides of the bladder, and carefully
raised towards the wall of the pelvis. The
muscle will then be seen to arise on each side
by three attachments, which, however, form one
continuous semicircular line extending from
the pubis to the spine of the Ischium; its
anterior portion is attached to the back part of
the pubis, a little above its arch, and imme-
diately below the anterior vesical ligaments by
short aponeurotic fibres commencing a little
distance from the symphysis, and extending
outwards as far as the notch in the thyroid —
hole ; its second or middle attachment is to
a strong tendinous arch, which extends from _
the pubis to the spine of the Ischium, and”
which is formed at the separation or junction
of the pelvic fascia into its superior or recto-
vesical layer, and its inferior or perineal layer;
its third or posterior attachment is to the spinous
process of the ischium. All the fibres pass
downwards and towards the median line te
their insertion; the inferior border of —
muscle is shorter but thicker than the superior.
The fibres of the first, or pubal portion, des-
cend a little obliquely backwards on each side

ANUS.

of the prostate gland and membranous portion
of the urethra, and converging beneath the
latter are inserted in common between the bulb
and the fore-part of the rectum into the central
point of the perineum ; these portions in their
descent present a well-defined edge inwards or
towards the median line. ‘The middle, or
aponeurotic portion, is broad and thin above,
the vesical fascia adhering so closely to it as to
render its separation difficult. As it descends
it increases in thickness, expands close to the
rectum, and is inserted into the coats of that
intestine, intermingling with its longitudinal
fibres, and with the sphincter ani; in the female
it is intimately attached to the vagina also.
The posterior or Ischiatic portion passes al-
most transversely inwards, and is inserted into
the coccyx, and into the cellulo-tendinous line
which extends from the latter to the rectum;
some fleshy fibres are continuous from one
muscle to the other. This portion of the le-
vator ani is more aponeurotic than the pre-
ceding, and its posterior border is connected to
the Ischio-coccygeeus muscle. The external or
inferior surface of this muscle is inclined down-
wards, and is more or less related to the obtu-
rator and ischio-rectal fascie, to the gluteus
maximus and transverse perineal muscles and
vessels, and to the mass of anal fat. The
internal or concave surface looks upwards, and
is closely covered by the vesical fascia, below
which it is in contact with the rectum, bladder,
prostate gland, and urethra, or with the uterus
and vagina. This muscle is disposed on the
rectum in the same manner in the female
as it is in the male; the fibres are also inti-
mately connected to the vagina.

_ The action of the levator ani muscles is
two-fold, and not confined to the mere ele-
vation of the anus, as its name would im-
ply. First, they act as a moveable floor to
the abdomen and pelvis, which can antago-
nize the diaphragm ; these two fleshy planes
being eppeed to each other, can, by a slight
action of one or both, materially alter the
perpendicular axis of the abdomen, which
extends between them. This axis is at its great-
est length during the state of expiration, and is
most diminished when both these muscles are
forcibly contracting. The levatores ani, how-
ever, have less influence in effecting this change
than the diaphragm; they serve chiefly to
support the lower region of the pelvis and the
several viscera this cavity contains against the
combined protruding forces of the diaphragm
and abdominal muscles in violent exertions of
the body, or in forcible efforts of respiration,
or in the evacuation of the contents of the rec-
tum and bladder; and, secondly, they not
only raise, but dilate the anus, by drawing out
its circumference so as to overcome the sphinc-
ters; at the same time they compress and
assist in emptying the rectum, particularly the
dilated pouch, which is a little above the anus;
they also resist the prolapsus of the mucous
coat of the intestine, and raise it after it has
been to a certain extent protruded by the action
of the abdominal muscles. They raise and draw

forward the coccyx after it has been forced back .

179
by abdominal pressure in parturition, or in the
ordinary evacuation of the bowels, and further,
by raising and compressing the trigone of the
bladder, they assist in expelling its contents,
and for the same reason they can also empty the
vesiculz seminales of their fluid. The anterior
portions of these muscles are intimately con-
nected to the membranous part of the urethra,
and are variously modified in different indi-
viduals and in different animals; we consider
those muscular fasciculi which have been de-
scribed differently by anatomical writers under
different names, compressores urethra, &c., as
parts of or appendages to these muscles: these
urethral portions of the levatores ani can cer-
tainly compress the membranous part of the
urethra and empty its canal; they can even
interrupt or suddenly stop the stream of urine,
and thus they may occasionally aid the neck of
the bladder in retaining the contents of that
organ.

The Ischio-coccyg@i muscles are situated at
the posterior inferior part of the pelvis; they
are thin, flat, and triangular, composed ofa mix-
ture of fleshy and tendinous fibres. The apex
or origin of each is attached to the spine of the
Ischium, and its base is inserted into all the side
of the coccyx, and a small portion of the
sacrum ; they are partly covered by the great
sciatic ligaments. The superior and posterior
border is connected to the lesser sciatic liga-
ment, and the anterior border is in part con-
tinuous with the levator ani muscle; the an-
terior or pelvic surface is connected to the
rectum and the surrounding adipose substance.
This pair of muscles appear as a prolongation
of the levatores ani, and are of use in com-
pleting the inferior boundary of the pelvis;
they thus support the rectum and the pelvic
viscera, and they also serve to retain the coccyx
and restore it to its situation when protruded by
thediaphragm and abdominal muscles in the pro-
cess of parturition, and in the act of defecation,
or when drawn too much forward by the levatores
ani muscles. If the several muscles in this
region be now partially removed on one side,
the lower extremity of the rectum will become
more distinct, and will be found surrounded by
a quantity of loose, fatty, cellular tissue, sepa-
rating it from the surrounding muscles and
bones; this contains many nervous filaments
and numerous bloodvessels, particularly veins.
(See Inrestinat Cana.) Anteriorly in the
male subject a small triangular space, the
bulbo-rectal hollow, will now become distinct;
this is situated between the anus and mem-
branous portion of the urethra; the base of it
is at the skin of the perineum; the apex at
the prostate: to the last the rectum will be
seen rather intimately connected. The bulb and
the membranous portion of the urethra bound
this space in front, and the rectum behind.
(See Perinzum and Urerura.)

Rectum.—- In addition to the several muscles
which have now been severally noticed, and
which thus serve not only to retain and support
the rectum and anus, but which even enter into
the structure of the former, we have further to
consider the parts more immediately composing
N 2

180° ANUS.

the parietes of the lower extremity of the in--
testine; these are the longitudinal muscular
fibres,—the mucous membrane, and the sub-
mucous cellular tissue. The longitudinal fibres
of the alimentary tube exist through its whole
extent, but like the circular are differently mo-
dified in different situations; thus along the ceso-
phagus they are very fully developed, also along
the arches of the stomach ; in both these situa-
tions the fibres are strong and somewhat red ;
whereas on the parietes of the small intestines
they are very indistinct and pale; on the cecum
and colon they are still pale, but very distinct,
being collected into three flat fasciculi or bands.
On the rectum, as on the cesophagus, they are
again fully developed as to thickness and num-
ber ; their colour is still rather pale. In the
two superior thirds of this intestine, or as low
down as the prostate gland, they predominate
over the circular fibres, which are internal,
whereas in the lower third the latter prevail ;
the former terminate, some by becoming con-
tinuous or intermingled with the fibres of the
levatores ani, others with the cutaneous sphinc-
ter so low as the border of the anus, and some
are inserted into the submucous tissue of the
intestine ; these fibres are continuous superiorly
with those of the colon; they serve to continue
that successive series of contractions or shorten-
ings of the intestine, which essentially assist in
the process of defecation. As the longitudinal
fibres of the rectum resemble those of the ceso-
phagus, so the inferior circular fasciculi or the
sphincters are like the muscles of the pharynx,
not merely in their increased strength and colour,
but also in their vital power. Over the lon-
gitudinal fibres the will has no control, whereas
the inferior circular are to a certain extent under
its influence. Here, then, as in the organs of
deglutition, we perceive the animal and organic
powers still distinct as to their elementary na-
ture, but becoming intimately, nay inseparably
associated for wise and obvious purposes.

In the act of defecation the offices of the se-
veral muscles connected with the anus may be
summed up as follows:—When the contents
of the rectum, particularly if of a solid con-
sistence, are being expelled, the whole rectum
descends, and the perineum becomes promi-
nent in consequence of the viscera being forced
against it by the contraction of the diaphragm
and abdominal muscles. The presence of the
feces irritates the muscular fibres of the rectum;
the longitudinal fibres shorten the intestine,
while the successive actions of the circular
urge down the fecal mass; these two orders
of muscular fibres are the true antagonists to
the sphincters. During this stage, however,
the sphincters are relaxed, and the anus be-
comes dilated, partly by the contents of the rec-
tum distending it, and partly by the levatores
ani muscles, which are nevertheless in a suffi-
ciently relaxed condition to allow the protru-
sion of the rectum and anus, while they still
support the latter to a certain extent, and thus
exert a sort of check against its forcible de-
scent; they also tend to open the orifice of
the anus. During this forcible expulsion, a
small portion of the mucous lining is frequently

protruded. The expulsion of the last portion
of feculent matter is then effected by the sub-

sequent strong and gradual contraction of the

levatores ani compressing the rectal pouch, and
raising the rectum and anus to their former

position, and lastly, the sudden action of the
sphincters clears and closes the orifice.

The mucous membrane lining the rectum is”

in every respect highly organized, it is thrown
into several folds, and is larger and looser
than the other coats, hence portions can be
easily removed by operation, and are not
unfrequently detached by gangrene. As it
approaches the anus, it is very red, soft, and
fungous, being highly vascular, presenting the
orifices of several glands, follicles, or lacune.
It is here very loosely connected to the muscu-
lar fibres, and is frequently found thrown into
irregular folds; these are protruded somewhat
during defecation, and when morbidly enlarged
or thickened, are not unfrequently the source
of considerable pain and inconvenience. As the
mucous membrane is not contractile, these folds
are necessarily increased when the longitudinal
fibres of the rectum contract and shorten the

intestine; they are then protruded together

with the fecal matter. Immediately above the
plaited margin of the anus the skin and mu-
cous membrane become continuous ; the ter-
mination of the cuticle appears rather abrupt,
just within the internal sphincter. Some de-
scribe it as continued higher up, and gradually
lost on the surface.
exhibit it satisfactorily higher than the point
indicated, nor does it appear to me that it

extends through this orifice by any means to”

the same extent as through the other outlets
of the body, the mouth, nose, urethra, or va-
gina. In the latter passage in particular it

is very distinct, even in health ; and in disease,

as in cases of prolapsus uteri, its develop-
ment becomes considerable; whereas in pro-
lapsus ani, that is, a protrusion of the mucous
lining of the rectum, at a little distance above

the anus, I have not found the protruded

mass to become covered with cuticle: I have
seen cases of long standing in which the surface
presented the same soft, vascular tissue as it
does at first. It does not controvert this state-
ment to find tumours about the margin of the
anus (hemorrhoids or polypi) covered with a
thickened or developed cuticle; for in such
cases the cutaneous covering is derived from
the elongation of the surrounding skin, which
has increased in density from exposure to the
air, and from continued irritation. The same
remark will apply to cases of artificial anus,

no matter in what situation: in all these the

villous surface, which protrudes during the
peristaltic action, retains its mucous charac-
ters, and does not become covered with cu-
ticle. From these facts it may be inferred
that cuticle is never developed in any situation
in which it did not originally exist, but that

circumstances favour the increase or more full

development of it in those situations where it
naturally occurs, even though its normal con-
dition be extremely delicate and fine.

Nerves and vessels.—The submucous tissue

I have not been able to’

ast oY eee ee |

a -

a ee

ANUS.

in the vicinity of the anus is very loose, and the
seat of nervous and vascular plexuses ; in the
latter the venous system predominates.
A consideration of the functions of the rec-
tum and of its surrounding muscles, its re-
markable irritability and sensibility in health,
as well as its sympathies in disease, would lead
us to infer what dissection proves to exist,
namely, that this organ is largely supplied with
nerves ; numerous branches are furnished to it
from the sacral plexus, which is formed by the
union of the inferior spinal nerves, also from
the hypogastric plexus, which is chiefly com-
posed of filaments of the sympathetic. The
sacral plexus of spinal nerves furnishes, in
addition to many others, the hemorrhoidal,
- vesical, and pudic branches; the hemorrhoidal
nerves are directed principally towards the in-
ferior part of the rectum, some ascend to the
colon, others descend even to the sphincter
ani: they divide into numerous filaments,
which are chiefly distributed to the muscular
fibres of the rectum and the adjacent muscles ;
the vesical nerves in their course to the bladder
give some filaments to the rectum, and the in-
ferior or perineal division of the pudic nerves
also send several branches to the levator and
sphincter ani muscles. The hypogastric plexus
of nerves is composed of filaments from the
sacral plexus, which interlace with some from
the inferior mesenteric plexus, and with nume-
rous branches from the sacral ganglions of the
sympathetic nerves. This plexus supplies the
rectum, as also the other pelvic viscera; the
branches accompany the bloodvessels, and are
distributed principally to the mucous and sub-
mucous tissue. e cellular tissue, also, about
the coccyx, and the adjacent muscular fibres
receive some filaments from the coccygeal plexus
of the sympathetic. This supply of nerves
from these two very different sources, the one
presiding over voluntary, the other over in-
voluntary motion, corresponds with the well-
known functions of this organ, and causes its
muscles to be classed by the physiologist under
the head of mixed muscles, that is, partaking
of the common characters of the animal or
voluntary, and the organic or involuntary sys-
tems. Its supply of spinal nerves serves to
explain not only the influence which the will can
exert over its functions, but also the impaired
or altered state of its powers in case of disease
or injury of the brain or spinal cord ; thus irrita-
tion of the latter may cause morbid irritability
and contraction of the rectum, and, necessarily,
constipation of the bowels; or, again, paralysis
of the spinal cord from injury-or compression
may lead to perfect atony of the sphincters, and
to the involuntary discharge of the contents of
the rectum. The general distribution of the
branches of the sacral and hypogastric plexuses
to the several pelvic viscera, and to the muscles,
&c. in the perineum, associates these different
organs with each other, which is so necessary to
their functions, and with the urinary and genera-
tive organs, connecting more particularly the
muscles of the anus with the muscular coat of
the urinary bladder and with the parts about

181
its cervix. This interlacement and subsequent
general distribution of these nerves serve also
to establish those several sympathies which are
found to exist in acute and chronic diseases of
the rectum and anus, between this intestine and
the other pelvic viscera. In some the uterus
and vagina partake of the irritation, in others
the urinary bladder is almost incessantly irri-
tated to expel its contents; or, on the other
hand, when the sympathetic irritation engages
its cervix and the parts in its vicinity, ‘the
most painful retention of urine is endured.
Chronic disease of this intestine is also very
generally attended with occasional attacks of
pain and irritation in different portions of the
alimentary canal, as also with pain in the
sacrum and loins, and in various. other direc-
tions, which may in most cases be explained by
referring them to nervous irritation extending in
the course of some of the nervous communica-
tions which are found to exist in such num-
bers in the pelvis.

The rectum, like the rest of the alimentary
canal, is freely supplied with blood. Its arte-
ries are named hemorrhoidal, and are derived
from three sources, viz., the abdominal aorta,
the internal iliac, and the internal pudic arte-
ries. The superior hemorrhoidal is the con-
tinuation of the inferior mesenteric, a branch of
the aorta; the middle hemorrhoidal is derived
either from the internal iliac or from some of
its branches; and the inferior or external he-
morrhoidal branches from the perineal division
of the pudic. The latter are destined directly
to the confines of the anus, and are lodged in
the subcutaneous adeps. The two former be-
long properly to the rectum, and are above the
levatores ani muscles. These arteries divide
into several sma!l branches, which anastomose
together, and form a continued chain of inos-
culations along this intestine, somewhat similar
to that which is continued along the whole of
the alimentary tube. They form a complicated
vascular net-work between and within the mus-
cular fibres, and are largely distributed to the
mucous and submucous tissues. Some branches
of considerable size not unfrequently descend
so low even as the sphincter, particularly at its
posterior parts. These are liable to be divided
in operations for the cure of fistule, and some-
times give rise to a hemorrhage, troublesome
and difficult to restrain. In such operations the
external hemorrhoidal arteries also are. very
commonly opened, and bleed smartly ; they can.
be secured, however, with much less difficulty
than the divided extremities of the superior or
middle hemorrhoidal vessels.

The whole of the rectum, particularly its
lower portion, is encompassed by numerous
veins, which in some persons are very large
and plexiform. In the perineum, also, many
venous plexuses are found in the subcutaneous
adeps. The external hemorrhoidal arteries
have their external vene comites, which run
outwardly to end in the internal pudic veins
(branches of the internal iliac). Some of their
branches ramify around the anus, and in some
cases form a plexus, in which hemorrhoidal

183

tumours are frequently developed; the mid-
dle hemorrhoidal veins are uncertain as to
number, size, and situation, but the superior
are very large and numerous; their branches
form repeated anastomoses in the submucous
tissue around the intestine, and frequently
present all the appearance of erectile tissue,
particularly in front, communicating below
with the perineal veins, before with a plexus
of vaginal or prostatic veins, and above with
the trunk of the inferior mesenteric which
leads to the vena porte. This latter communi-
cation, as also the absence of valves in the
portal system, has laid the foundation of the
practice of applying leeches to the anal region
in chronic inflammatory affections of the liver
and bowels. The same facts also have been
adduced to explain the frequency of hemor-
rhoids, varices, and vascular congestion about
the anus and rectum in cases of diseased and
hardened liver, which, under such circum-
Stances, is supposed to obstruct the circulation
by impeding the returning blood through the
vene porte.

ABNORMAL CONDITION OF THE ANUS AND

NEIGHBOURING PARTS.

Congenital malformations.—The lower ex-
tremity of the rectum and anus not unfre-
quently present in the new-born fetus con-
genital malformations, some of which are in-
compatible with continued existence, while
others admit of protracted suffering, with great
inconvenience and imminent danger to life;
while, again, some may be relieved by the in-
terference of art. Hence it is necessary to con-
sider these anomalous appearances with a view
to discriminate those which are curable from
those in which all remedial attempts are totally
useless. The following congenital malforma-
tions have been noticed by surgical writers,
some of which have come under our own ob-
servation.

1. The anus has appeared at first view to be
natural, but on a more accurate examination
no canal has been found above it; and after
death it was discovered that the rectum was
absent, that the left colon ended in a cul de
sac, and that a dense fatty substance occupied
the situation of the rest of the canal. It is plain
that no operative interference could avail in
such a case. In some cases of this want of
rectum the anus has been absent also.*

2. The anus and rectum have appeared
natural, but after death it has been found that
the latter was interrupted in one part of its
course, and that the intestine had ended above
that in a cul de sac. This state of parts must
lead to the same practical conclusion as that
last mentioned. In these and in such like cases
of unhappy malformation, some have suggested,
as a “ dernier resort,” the propriety of opening
the intestinal canal at some point in the abdo-
men, So as to evacuate its contents and establish
permanently an artificial anus. The proposal
was first made by Littre,+ of opening the

* See Dict. des Sciences Med. t. xxiv. p. 129,
+ Mem. de l’Academ. des Sciences, 1720,

ANUS.

sigmoid flexure of the colon in the left iliae
region. A successful case of this operation is —
recorded as having been performed by Duset*
on a boy twenty-four hours after birth: the
child was reported, at twelve years of age, to
be in good health, with an artificial anus esta-
blished in the left iliac fossa.+ ’

3. No anus, but the rectum has opened into,
and its contents escaped either by the urethra
in the male, or by the vagina in the female.
This condition is an approximation to the
cloaca of birds, and of some fishes. Life may
continue under such an arrangement, particu-
larly in the female, when the intestine opens
into the vagina, with great inconvenience no
doubt; but in the male the prognosis cannot
even be so favourable, as the urethra can
scarcely suffice to give exit to the feces after
some time; and as the bladder and organs in
its vicinity will be subject to constant irrita-
tion. Cases are, however, recorded of life
being protracted for several months; and in
one case, a boy, who lived for eight months,
on examination after death it was found that a .
cherry-stone had blocked up the passage of
communication between the rectum and ure- }
thra. In such a state of parts it has been ad-
vised to cut through the perineum in the situa=
tion of the anus, and endeavour to open the |
extremity of the rectum. The bladder should 5
be previously emptied of urine, and a sound
or staff be retained in it, as a guide to the
operator to protect it from injury. In the A
other somewhat parallel condition of these ;
parts in the female, the exit for the alvine mat- 4
ters is usually more free ; and several cases are ;
on record of life being continued for several 4
years. ‘These cases offer more encouragement
for operative interference than the former. A
curved probe may be passed from the orifice
in the vagina into the rectum, and then directed
towards the perineum to the situation of the
anus. An incision is to be then made upon
it; and when the canal of the rectum is thus
opened to the surface, the channel is to be kept
carefully dilated, in order to oppose the natural
tendency in the parts to close.

4. The anus may be open, but the con-
tents of the intestine retained, in consequence
of a congenital contraction of the rectum at
some distance above, owing either to a mem-
branous septum extending across it, or to a
circular thickening and contraction. Such cases
may be overlooked, and their cause remain
unknown until after death: in cases, therefore,
of obstinate constipation at this early age, this
part should be particularly examined. Petit f
describes this condition, and mentions a case —
in which he detected such an obstruction in the
rectum, about an inch above the anus. This —
he divided by a pharyngotome, with success.
The division may be effected by a bistoury, if —
situated low down; or by a trochar, if at a
considerable distance from the anus. as.

* Recueil Periodique de la Société de Méd. de
Paris, t. iv. p, 45. ib a
+ Dict. des Sciences Méd. t. xxiv. p. 126. — 1a
t Mem. de l’Acad. de Chirurg. t. i. p. 385. 0

ANUS.

5. No anus, but the rectum is continued
pervious as far as the integuments, which in
some cases are then prominent, and of a violet
colour, from the meconium appearing through
in the situation which the anal opening should
occupy. In other cases the skin is thick and hard,
and gives no indication of the situation of the
rectum. In such circumstances the surgeon must
divide the integuments, either by a crucial or by
a transverse and longitudinal incision, and then
proceed cautiously until he exposes the dis-
tended rectum. When the skin only inter-
venes, the prognosis as to the result of this
operation may be favourable, as the sphincters
are probably perfect; but when the cul-de-sac
of the rectum is deep-seated, then experience
affords but little encouragement to hope for
success. Death is inevitable in such cases,
unless relief can be afforded, and but very few
cases of successful operations are on record.*

6. The anus and the continuous portion of
the rectum are so contracted as scarcely to
admit of any fluid discharge: we have even seen
it scarcely pervious to air, so that on forcing in
a grooved director, a considerable burst of flatus
has oe This contraction may exist be-
low, and yet the rectum be perfectly natural
above. ‘This contraction is sometimes not
sufficiently noticed for several days or perhaps
weeks after birth, because occasionally there is
a small discharge of fecal matter; it ultimately,
however, excites attention from the great diffi-
culty, straining, pain, and crying manifested
at each evacuation. This condition of the

rts sometimes admits of relief, by simple
dilatation, by introducing a soft bougie, or
some prepared sponge, which should be re-
placed after each evacuation, and secured, if
— by adhesive plaster and a bandage.

hould these means fail, an effectual cure may
be obtained, as we have seen, by a division of
the circumference. This may be done by intro-
ducing into the rectum a button-pointed bis-
toury for about an inch on a director, and
dividing the wall of the intestine transversely,
towards the ischium, first on one side, and then
on the other, to the depth of about one quarter
ofaninch. The part must be carefully dressed,
and the edges of each wound kept separate by
lint. The success of the operation greatly de-
pends on the care in the after treatment, par-
ticularly in renewing the dressing whenever it
has been displaced.

The anus is occasionally found much con-
tracted in new-born children who are con-
taminated by syphilis, and may be mistaken for
a congenital malformation, especially of the kind
last noticed, though not one in the strict sense
of the expression; yet as it generally occurs
at birth, it deserves the consideration of the
practitioner in midwifery, whose attention is
often first called to it by the same symptoms
that attend the congenital malformation of this
opening, namely, pain, difficulty, and straining
at each evacuation, and a peculiarly sma!l aper-
ture. On examination, however, there are

* See some observations by Petit, Mem. de
PAcad. de Chirurg. t. i. p. 378.

*

183

other appearances which will assist in explain-"
ing the real nature of the case, such as brown -
or dark discolouration of the surrounding parts, ~
also considerable moisture, frequently excoria-
tion, and even superficial ulceration in the adja-
cent structures. Small fissures in the anus, also,
are observable, discharging tenacious matter.
Similar appearances may exist about the com-
missures of the lips; some soft granulations or
condylomata are also often present in the im-
mediate vicinity of the anus ; these frequently
extend into the canal for a very little way.
Other constitutional symptoms also are usually
present, such as copper-coloured blotches on
the skin, a tendency to cracking and excoriation
of the skin about the hands and feet, and but-
tocks, an imperfect development of, or a ten-
dency to a separation of the nails, general
emaciation, suspicious appearances about the
mouth and tongue, and a remarkable and
peculiar hoarseness in crying. Many, if not
most of these symptoms, aided sometimes by
the history of the parents, will lead the prac-
titioner to distinguish this contraction of the
anus from the congenital malformation before
described. The distinction is important, as the
treatment in both is totally different; the syphi-
litic contraction invariably yields to gentle

‘courses of mercury, administered in such form

and dose as the circumstance of the case shall
denote to be necessary. The local complaint
disappears as the constitution is restored to
health. Soothing, emollient applications are
the best topical remedies ; should there be any
ulceration or excoriation about the part, the
surface should be slightly stimulated daily,
either by caustic or by the ordinary mercurial
lotions.

Morbid conditions—The anus is the seat of
several morbid affections, some of which pro-
ceed from a specific cause; others are merely
local. The specific diseases are syphilis and
cancer; and the most common hac derange-
ments to which the anus is subject are, super-
ficial ulcerations, excoriations, fissures, with or
without contraction of the orifice from exces-
sive irritability of the sphincter muscle, pro-
lapsus ani, hemorrhoids, fistula in ano, polypi,
&c. Some of these last mentioned affections
must, strictly speaking, be considered as ap-
pertaining to the rectum, under which head
the reader will find them noticed. As, how-
ever, the anus is more or less engaged in these
diseases, we shall make some observations on
each. The anus is also subject to laceration in
parturition, and from other causes.

Syphilis affects the anus at all ages; its ap
pearances in the infant have been already
noticed. In the adult it may present the primary
venereal ulcer, which will have the same cha-
racter here as elsewhere, only somewhat modi-
fied by the position and function of the part.
The primary ulcer may be produced either by
the d.rect; application of the virus, or by ex-
tension of ulceration from the neighbouring
organs, as not unfrequently occurs in the
female. When the chancre is confined to the
anus, which is very seldom the case, it may be
difticult to discriminate betweer it and ulcera-

184

tions from other causes. Ulcers in this region
are very generally difficult and slow to heal,
owing to the irritation to which they are exposed
from the passage of the feces, and from the
motion, pressure, and changes of form to which
the parts are necessarily subject. Syphilis
frequently appears here in the form of fissures,
clefts, rhagades: these are very distinct, and
different from the fissures attending the irri-
table anus. The syphilitic fissure is chiefly in
the integuments; it seldom extends to any
distance within the anus: the edges are some-
what elevated and thickened, and the surface
secretes an adhesive pus, which forms crusts
or scabs. Although in some instances these
fissures or rhagades are attended with pain in de-
fecation, yet we have met many cases in which
they caused very little uneasiness, and thus
contrasted remarkably with the simple or the
irritable fissure. Warts, condylomata, or ex-
crescences about the anus are also frequent
effects of syphilis in this region. These are
generally on the cutaneous side of the anus,
and very rarely, I believe, extend within it:
they are not, therefore, difficult to distinguish
from those vascular excrescences which are of
mucous origin, and which so commonly pro-
trude at the anus. Syphilitic warts and con-
dylomata have generally a broad base; their
surface is flattened by pressure against the op-
posite nates, soft and moistened with an offen-
sive sero-purulent fluid. In these cases the
surrounding skin is often excoriated, and clefts
and superficial ulcers frequently exist in the
vicinity of the anus.

Cancer is a disease to which the rectum is
very liable, and may attack any part of the
intestine, but usually exists at some inches
above the anus. This opening, however, may
become implicated by the extension of the dis-
ease. We occasionally see that form of cutaneous
cancer called “cancer scrote” extend along the
perineum and involve the circumference of the
anus. Its parietes may, however, be prima-
rily affected by cancer, in which case the
disease will commence by a chap or fissure,
or more frequently by a tubercle, which, gra-
dually increasing in size and in breadth, at
length ulcerates and shoots out a cauliflower
mass of granulations which protrude through the
opening, causing great uneasiness, pain, and dif-
ficulty in defecation: the surrounding parts in
time become involved, ulceration extends, and
a bleeding surface, very unhealthy, sloughy in
some parts, and fungoid in others, discharging
sanious and unhealthy matter, is an almost in-
cessant source of pain and irritation, which in
time wastes the health and strength of the
patient. As no local application or consti-
tutional treatment has yet been able to arrest
this disease, it has been proposed to extirpate
the anus and the lower end of the rectum when
in this condition. Unfavourable as this opera-
tion may appear, and rarely as it has been

-undertaken in this country, it has been fre-
quently performed in France, and with some
success.*

* See Velpeau, Med. Oper. t. iii. p. 1033.

ANUS.

The anus is often affected with warty ex-
crescences, which by a superficial observer might
be condemned as cancerous, yet these are not
of a malignant character, and may be cured by
local remedies and due attention to the gene-
ral health. I have seen a warty tubercular
appearance about the anus, extending through
it, and even involving the mucous surface for
some height, and contracting the orifice so
much as to cause great pain and difficulty in
defecation, and also materially impairing
the general health by continual irritation; yet
this state of parts is not malignant, nor is it
prone to ulceration. Attention to the consti-
tution, to the functions of the bowels, with
local applications, will effect a cure. The anus
is also frequently affected, and even incon-
venienced by the growth of common warts ;
these, however, can be speedily removed either
by the scissors or by caustic.

Excrescences frequently protrude through the
anal opening, which are not warty or cutaneous
growths, but elongations of the mucous mem-
brane from a little distance above the anus.
The anatomical disposition of these parts, before
alluded to, together with a very relaxed state
of the mucous membrane, accounts for the fre-
quency of this occurrence. ‘In some these pro-
trusions only appear during defecation, in others
they are permanent, but much increased in
volume during that act; and, indeed, in some
they are so large and fill up so much of the
canal, that they must be extruded before the
feeces can escape. These excrescences are soft,
and very vascular; they often appear without
any assignable cause, though frequently they are
attributed to hemorrhoids, to constipation of
the bowels, to violent straining efforts in de-
feecation, to fistula, or to long-continued irrita-
tion from any cause.

Prolapsus ani, or procidentia ani, although
a term in somewhat common use, is rather an
incorrect one, as the anus itself is too well
maintained in its situation to descend, at least to
any appreciable distance; the term rather implies
a protrusion of a considerable portion of the
relaxed mucous membrane of the rectum, ora
portion of the large intestine itself, which must
have become “ invaginated or introsuscepted,”
and then protruded through the anus; in these
conditions the anus is rather dilated, the mu-
cous membrane sometimes remains protruded
after defecation, but in others it returns after
this proeess, or it can be returned by the gentle
pressure of the hand: this is not uncommon
in children and in elderly persons. This disease
has been ascribed toa relaxation of the sphincter ;
a circumstance which, however, does not seem
to be proved, for in paraplegia and in paralysis
of the sphincter, we do not find that the mem-
brane protrudes, although the anus is often in
these cases very dilatable; the condition referred
to ought perhaps rather to be considered as one

of the effects, than as the cause of the disease; _

moreover in some other instances the sphincter

appears rather irritable, and painfully and dan- —

gerously constricts the protruded mass, which
must then, in order to save the intestine from

_ gangrene, be reduced by pressure properly

%

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.
.
k
.
3

ANUS.

applied, and by attention to posture. In the
procidentia of old persons, Mr. Hey conceives
that the relaxed state of the lower part of the
intestine and of its surrounding cellular tissue,

are in fault, and that hence the folds or ex- —

crescences about the anus remain, even when
the parts have been returned ; he therefore sug-
gests the removal of these flaps from the cir-
cumference of the opening, and relates some
well-marked cases in support of this practice,
in which the operation had been successfully
performed.
. The margin of the anus, like that of the
mouth, is subject to fissures, chaps, and super-
ficial excoriations, sometimes caused by lace-
ration induced by the passage of large and
hardened feces, but sometimes arising spon-
taneously, and sometimes connected with a
peculiarly irritable and contractile condition of
the sphincter ani. This disease must not be
confounded with hemorrhoids; on examin-
ation it is not easily seen, but little is appa-
rent, the anus is much contracted, the orifice
somewhat redder than natural, slightly tender
on pressure, but exquisitely so on dilating it
by introducing the finger; this must be done
cautiously and slowly, a cleft will then be
observed just where the skin and mucous
membrane join, generally on one side extending
a little way, from half an inch to an inch and
a half, longitudinally up the intestine; on di-
lating the part still more, the surface of the
fissure will be seen slightly ulcerated, and
when touched it is exquisitely painful; the
surrounding muscle is in a state of rigid con-
traction. It is doubtful whether the contrac-
tion is the cause of the fissure, or whether the
latter is the cause of the irritable and con-
tracted condition of the muscle. Both expla-
nations may be occasionally correct; but it is
most probable that the irmtable state of the
muscle induces the ulcerated fissure, inasmuch
as this muscular contraction occasionally exists
without any fissure, and is then equally pain-
ful; and fissures frequently exist, as in syphilis,
without inducing any spasmodic constriction
of the muscle, and accordingly are attended
with little or no pain.

Contraction of the anus also frequently ex-
ists without any fissure; sometimes it is con-
genital, sometimes it appears in the adult; the
pain and other symptoms are nearly analogous,
and as severe as in the case of fissure; the
examination by the finger however does not
detect one part to be more painful than another,
as is the case in that disease; and this is almost
the only symptom distinguishing these two
-affections.

The term hemorrhoid has been applied by
writers, practitioners, and invalids to any con-
dition of the rectum and anus in which a
discharge of blood takes place. It is, how-
ever, more correctly applied to the small tu-
-mours which are frequently seen at and very
_close to the inner border of the anus or even
occupying the very aperture, also to somewhat
. similar productions situated within the rectum,
at the distance of one, two, or even three
_inehes above the anus. From such tumours

185

occupying these different positions, they have
been arranged by all writers into erternal and
internal hemorrhoids; the latter are very im-
portant and demand the close attention of the
surgeon, both as to their pathology and sym-

-_ptoms, as being frequently obscure and liable

to be mistaken not merely for the ordinary
diseases of the anus, such as fissure, blind
internal fistula, &c., but also to be confounded
with a varicose condition of the veins of the
rectum, which is by no means an uncommon
condition, or with those vascular tumours
which are productions of the mucous mem-
brane occasionally protruding at the anus,
that have been already noticed, and are
of a wholly different character from -true he-
morrhoidal tumours, or with the protrusions
of the mucous membrane itself, the effect of
the relaxation of its cellular connections. As
the full consideration of this important branch
of pathology belongs to the article on the mor-
bid anatomy of the rectum, we shall here con-
fine ourselves to a few observations on external
hemorrhoids and analogous tumours.

External hemorrhoids appear at the border
of the anus as small bluish tumours, the
colour however varying according to the con-
dition of the tumours, being sometimes of a
dark and deep red or black, at others pale and
almost white; in size they vary from a grain
of small shot to a large cherry; they are some-
times full and almost bursting, at others they
are soft like a flaccid nipple, empty or with-
ered; they are covered on the anal side by the
delicate cuticle which is smooth and glossy,
and on the outer side by the common integu-
ment; when small, they are moveable and can
be distinctly felt to be in the subcutaneous
cellular tissue ; when large and tense, they ap-
pear more connected with the skin itself;
an attentive examination can always distinguish
between these and the several excrescences,
vegetations, or condylomata, which have been
already mentioned as the effects of syphilis,
as also the folds or crests of integument and
mucous membrane which are found so fre-
quently prolonged from the border of the
anus. These tumours remain in many persons
for years free from pain, and productive of
little, if of any, inconvenience ; occasionally,
however, and periodically in some, they en-
large, inflame, and interfere with the functions
of the anus, and by sympathy engage the ad-
jacent organs, and are relieved either by a
copious discharge of blood, or by suppuration,
or by the interference of art.

The liability of the veins immediately about
the anus to varicose enlargement appears in
some measure founded in anatomical structure.
If we inject the intestinal veins in the adult
with wax injection, we shall often find a little
above the anus, just where the skin and mu-
cous membrane unite, a sort of constriction on
the vessels; the veins appear larger imme-
diately above it, and again below it, and
many of the branches in the venous plexus
around the anus appear to be enlarged, while

in the very spot or circular line alluded to,

the vessels appear to be compressed. It may

186

occur, then, that hardened feces impacted in
the rectal pouch, which is above this point, may
assist in obstructing the more free flow of
blood, and thus encourage the enlargement
of these anal veins, and the same effect may
be still further induced by the muscular pres-
sure employed in defecation; in support of
this view we find that children are almost free
from this varicose condition of these veins,
unless under peculiar circumstances ; and in
the adult it usually occurs in those of con-
stipated habit of bowels; it is also relieved or
removed by attention to their functions. The
true hemorrhoidal tumours, external as well as
internal, must be regarded as essentially dif-
ferent from a varicose condition of the anal
veins, although they are often connected with
the latter, and it must be admitted that un
some cases they may owe their origin in a great
measure to venous dilatation. Varices of the
anal veins are simple dilatations either of a
trunk or of some of the branches of these
vessels ; their cavity is continuous with that of
the vein, and freely communicates with it,
and pressure on the varix empties it of its
contents ; its tunics are the venous coats and
the membrane of the intestine; whereas hzemor-
rhoidal tumours are wholly distinct from the
veins, and are either simple cysts, lined by
a smooth membrane, or they are composed
of a spongy cellular texture, not unlike the
erectile tissue. This latter is usually the con-
dition of recently formed hemorrhoids, whereas
in those of long standing the single or divided
cyst is the ordinary structure; this cyst will be
found to contain a little blood, partly fluid
and partly coagulated ; and when the internal
surface is minutely examined, one or more
fine pores will be visible, the orifices of ca-
pillary vessels, through which warm water,
if steadily injected by the inferior mesenteric
artery, will exude on the surface. In the cellular
or more recent hemorrhoids the texture ap-
pears very vascular, soft, and spongy, as also
the surface of the tumour, from which blood or
serum will sometimes exude during life.
These cellular hemorrhoids in time become
circumscribed, the cellular texture becomes
more or less perfectly absorbed, and the cyst-
like structure becomes more developed ; how-
ever a very recently formed hemorrhoid may,
and sometimes does, present a distinct cyst or
cavity, as may be readily conceived when we
consider the process whereby these tumours
come to be developed, which, as far as our
observation extends, is as follows: from con-
tinued irritation from any exciting cause, such
as disease of the intestine or anus, worms, or
from a local plethoric condition, spontaneous,
as far as we can know, the capillary circulation
is increased in the loose submucous tissue in
this region, a small quantity of blood, or
lymph, or serum, is effused into it, perhaps
from the rupture of some small vessels, or
exhaled from their dilated extremities. A
slight degree of inflammation attends this con-
dition: the part affected, that is, the cellular
tissue, becomes more highly organized, thick-
ened, vascular, and spongy. After some time,

AN US. ;

this increased vascular action subsides, and in
process of time the whole may nearly dis-
appear, but in general a part of this more
highly organized spongy tissue remains, it
being fully supplied with nourishment; the
absorbents in due course modify its appear-
ance; the surrounding thickening is removed,
as also some portion of the cellular mass,
and thus the formation of the hemorrhoidal
cyst is completed. A structure like this, con-
nected with the capillary system, must be
influenced by the same causes as can affect
the latter ; thus irritation local or general, me-
chanical injury, or general or local plethora
are all capable of exciting increased action in it,
and of inducing all those symptoms and changes
which are so well known to attend during
hemorrhoidal inflammation.

Fistula in ano is a disease of such very fre-
quent occurrence, and so well understood and
described by every surgical writer, that it is .
scarcely necessary to do more than allude to
it in this place: strictly speaking it is nota
disease of the anus, as that opening is in
general totally unaffected, except as regards its
functions: it should rather be regarded asa
disease of the anal region. There is one form
of fistula in ano, however, which is seated on
the very confines of this opening; it is trou- d
blesome and distressing, attended with heat,
itching, and excoriation, pain during defeca-
tion, and constant purulent or sero-purulent
discharge: without due attention it may be
overlooked by the surgeon, as the orifice is so ;
close to the anus as to, be concealed by the |
natural ruge, and so small as only to admit a |
lachrymal probe; the sinus is not more than
an inch or half an inch long; its internal
opening is on the very edge of the anus, the
whole is immediately under the skin, and does
not involve any other structure; it is not pre-
ceded by regular abscess, neither does it or the

ee eee en ee

treatment necessary for its cure involve the S
sphincter or any other structure, except the F
fine integuments; it most probably originates
in irritation of some of the anal sebaceous 7

follicles, and sometimes two or three of such
fistulee may exist at the same time.

The true or deep fistula in ano has its origin
in deep-seated abscess commencing close to
the rectum, or in the centre of the ischio-rectal
space of either side: when in the former,
some mechanical irritant or some disease of
the intestine may have been the cause or
origin of the abscess; when in the latter, it
often arises without any obvious reason, but
frequently appears to have been connected
with some peculiar delicate or morbid con-
dition of the constitution. All abscesses in
this situation do not necessarily end in fistula;
if they have been small, superficial, opened —
early, and treated judiciously, they may be —
healed as perfectly as abscesses in any other —
situation; but when deap-seated, of slow —
growth, and long continuance, and when de- —
pending on some deep-seated mechanical irri- —
tant or on constitutional causes, then the ab- —
scess usually attains considerable size,’ and —
having opened either into the rectum or through —

AORTA.

the integuments, or in both these directions,
it continues to secrete and to discharge a con-
siderable quantity, and shews no disposition to
alter its action or to heal. We have already
detailed all the local peculiarities of the ischio-
rectal region (the seat of this abscess) which
can satisfactorily explain the difficulty or the
impossibility of keeping at rest or retaining in
apposition the sides of the cavity, a condition
almost essential to the healing of an abscess in
any situation, and hence the necessity of sur-
gical interference. Abscess in this region
frequently originates close to the rectum in
consequence of irritation and ulceration in this
intestine; this irritation may be caused by
disease, such as cancer or stricture of the
rectum, or by some foreign body becoming
impacted in one of the lacune. Above the
sphincter is the rectal pouch, and an irre-
gularly shaped or sharp substance, such as a
pin, a fish-bone, or one of the small bones of
a fowl, &c. brought into this in the feecal mass,
may catch in its villous or rugous surface, the
muscular powers of the intestine are excited
by this irritation to increased and repeated
efforts of expulsion ; these only serve to im-
pact more closely the foreign body in the
parietes of the intestine ; the submucous tissue,
which may now contain the whole or part of
this substance, becomes inflamed, suppuration
follows, an abscess is formed close to the intes-
tine; in some time the matter is discharged
either through the rectum and anus, or coming
to the surface of the nates it receives exit by
puncture. In this case of abscess, which we
suppose to have been caused by a foreign body
impacted in the intestine, the matter is usu-
ally discharged by the rectum, at least at first,
although this exit will not always prevent it
still tending towards the cutaneous surface :
in cases of fistula, however, arising from such
a cause, we are most likely to meet with the
blind internal fistula, at least in the early
period; whereas, when abscess forms spon-
taneously in this region, and opens on the
surface, the intestine is often at first and for
some time wholly disengaged from the disease,
even after the abscess has opened, notwith-
Standing which it is productive of great in-
convenience and more or less of pain during
defecation ; in this state, when the fistula or
abscess remains discharging through the skin
only, it constitutes what is termed a blind
external fistula; by degrees the rectum be-
comes denuded, and ultimately ulceration
‘opens it by one, and sometimes, but rarely,
by more orifices; this opening is usually about
half an inch above the edge of the anus, and
between the two sphincters. I have observed
it to hold this situation in a great number of
eases, which I have examined both in the
living and the dead; in a few instances, how-
ever, I have found it opening at a higher point.
When the abscess arises from irritation in the
rectum, then I have observed the internal
opening to be higher, that is, in the dilated
pouch of the rectum, which during life will
appear to be from an inch and a half to two
i from the anus; but when the abscess

187

has commenced spontaneously in the anal
adeps, and opened on the surface first, I have
then in general found the rectal opening less
than an inch distant from the anal orifice, and
in a groove or recess between the two sphinc-
ters. When the abscess discharges by two
openings, that is, through the skin and through
the rectum, a perfect or complete fistula is then
said to exist. .

Fistule occasionally appear in the anal region
which have their source at a much greater dis-
tance; thus, any diseases of the uterus or
vagina in the female, of the prostate or urethra
in the male, which end in suppuration, may
cause collections of pus which will burrow
under the fascie and skin to the vicinity of
the anus, and open near it or even into the
rectum. Psoas and lumbar abscesses also may
descend into the pelvis and approach the sur-
face, either in front or at one side of the anus.
In morbus coxe also chronic abscesses which
form about the nates not unfrequently open in
the same situation.

Polypus is seldom a disease of the anus; it
most usually grows from the rectum, and pro-
trudes occasionally only at the anus.

(Robert Harrison. )

For the Bibliography of this article see that
of InrestrnaL Canat.

AORTA* (human anatomy).—( Arteria
magna. Fr. aorte. Germ. Aorta, die grosse
Schlagader. Gr. aogr’.) Hippocrates applied
the term awogras to the lower part of the bronchi.
Aristotle called the great trunk of the arterial
system OAs) aoeri.

The aorta, one of the two great arteries
which spring from the heart, is the trunk of the
arterial system of the general circulation; it
arises from the extreme right part of the base
of the left ventricle of the heart, which, from
this circumstance, is sometimes called the
aortic ventricle. There is a ring of tendinous
structure surrounding the aortic opening of the
ventricle, which in the stag and some others of
the ruminantia is more or less partially ossified ;
into this ring the muscular fibres of the heart
are inserted. The middle tunic of the aorta
is divided at its commencement into three
semicircular flaps by an equal number of angu-
lar notches, forming thus a festooned edge
which is bordered throughout its whole extent
by a marginal tendinous cord. These three
semicircular flaps touch the aortic opening of

* The etymology of this term is by no means
clear. The following extract from Spigelius (de
corp. hum. fabrica) gives a not improbable origin
fer it.—‘‘Veteribus Gracis aoprny dictam fuisse
vaginam cultrorum Macedonibus familiarem, quo~
rum mannbrium nonnihil incurvatum erat, ad quam
sane figuram quam proxime accedere videtur arte-
riz magne truncus, qua parte ex corde originem
suam ducit.”” Cloquet suggests the theme, aoprsopsat,
suspendor, “ parceque l’aorte considerée dans sa
totalité parait comme suspendue au cour. Aris-
totle, by whom the term seems to have been first
employed, generally denominated it prey tharray,
in reference to the vena cava, which he considered
the greater vein.—R. B. T.

-188

the ventricle at three equidistant points by the
centres of their convex edges, where the fibres
of their marginal cord become intimately
blended with those of the tendinous ring of the
aortic opening of the ventricle; between these
points are three triangular intervals, each of
which is occupied by a thin tendinous expansion
of considerable strength, having one of its sides
continuous with the tendon which encircles
the aortic opening of the ventricle, and the
other two continuous with the marginal ten-
dinous cord of the festooned commencement
of the middle tunic of the aorta.

The convex margins of the sigmoid valves of
the aorta are attached to the margins of the
semilunar flaps, and are composed of thin ex-
-pansions sent off from their marginal tendinous
cord, covered by a reflexion of the lining mem-
-brane common to the heart and arteries. Hence
it follows that the fibres of the middle tunic
of the aorta are not continuous with the
muscular fibres of the ventricle, being sepa-
rated from them by the tendinous structure
above described ; this tendinous connexion is
strengthened and supported externally by a
layer of dense cellular membrane, which may
be regarded as the commencement of the
cellular or external tunic of the arterial
system. The lining membrane of the heart,
after being reflected over the sigmoid valves,
extends itself into the aorta, and becomes
continuous with the lining membrane of that
vessel. The muscular substance of the heart
rises in form of a swollen annular border
around the commencement of the aorta for a
little distance, and is connected to it by dense
cellular membrane. The serous layer of the
pericardium passes loosely from the surface
of the heart over the aorta; a quantity of
soft adipose substance, which is absent in the
foetus during the earlier months, begins to
collect under the serous membrane in this
situation, sometimes before, sometimes after
birth, and, increasing as life advances, is found
in considerable quantity in old age. The fore-
going description of the connexion of the aorta
with the heart has been determined by my own
dissections repeatedly performed, and agrees, in
its leading particulars, with the account given
‘of it by M. Beclard.*

The aorta, arising from the left ventricle
of the heart opposite the left side of the body
of the fourth thoracic vertebra, ascends at first
obliquely forwards, and to the right behind the
middle bone of the sternum, until it arrives
at the right side opposite the second intercostal
space, and behind the sternal articulation of
the cartilage of the second rib; it then stretches
backwards and to the left, opposite the junction
of the upper and middle portions of the ster-
num, on a level with the body of the second
thoracic vertebra, and curving downwards it
reaches the left side of the body of the third
thoracic vertebra, on which there is a slight
depression for lodging it; from this point it
descends through the posterior mediastinum,

* Dict. de Médecine, art. Aortee Elemens
d’Anat. Générale, par Beclard. Paris, 1823.

“AORTA.

advancing in its course downwards from the
left side to the front of the bodies of the ver-
tebre ; it passes through the aortic opening of
the diaphragm, enters the abdomen, and on the
body of the fourth abdominal vertebra gives
off the two primitive iliac arteries, in which it
seems at first view to terminate; the aorta,
however, does not end here, but is continued,

although greatly reduced in size, under the

name of the middle sacral artery, as far as
the extremity of the os coccygis.

The aorta is usually divided by anatomists
into three portions; the curved portion from
the heart to the third thoracic vertebra is called
the Arch of the aorta; the remaining portion
of the vessel, to which the name of descending
aorta has been sometimes given, is called
Thoracic aorta above the diaphragm, and Ab-
dominal aorta below that muscle.

The Arch of the aorta is divided into three
portions, for the purpose of describing its nu-
merous important relations to surrounding parts
with greater accuracy; these are, first, the
ascending or anterior limb; second, the trans-
verse portion; and, thirdly, the descending or
posterior limb. The commencement of the ~
aorta is covered anteriorly and to the left by
the pulmonary artery, on the right by the right
auricular appendage, the tip of which overlaps
it in front, and behind it rests on the sinus
of the left auricle. The ascending limb of the
arch lies first in front of the right pulmonary
artery, as that vessel crosses behind it in its
course to the right lung, and then it gets in front
of the right bronchus, and the cluster of bron-
chial glands which fill up the angle formed by
the bifurcation of the trachea; it is bounded
on the right side by the superior vena cava,
and on the left by the pulmonary artery ; an-
teriorly it is separated from the sternum by the
anterior margins of both lungs, which here
approximate, and by the narrowest part of the
anterior mediastinum, where the attached sur-
faces of the opposite pleure touch. This
portion of the aorta is contained within the bag
of the pericardium, the serous layer of which
invests it in every part except where it lies
in contact with the pulmonary artery.

The transverse portion of the arch is shorter
than the ascending limb. The three great arte-
ries of the head and upper extremities arise
from its superior sides ; inferiorly it rests on the
left bronchial tube ; in front it has the cellular
membrane of the anterior mediastinum, the
thymus gland, and the inferior part of the vena
innominata; behind it rests on the trachea a
little above its bifurcation, and on the left re-
current nerve. The posterior limb is the shortest
portion of the arch; it lies immediately behind
the division of the pulmonary artery, which
is connected to it by a ligament, the remains of
the ductus arteriosus ; and it is crossed by the
left par vagum; on the right side it is in con-
tact with the cesophagus, thoracic duct, and
left side of the body of the third thoracic ver- —
tebra; the rest of the circumference of the
thoracic aorta is covered by the left pleura, and
is in contact with the internal surface of the
left lung.

In the generality of adults having —

~

TRS

AORTA.

the chest well formed, and the heart and the
arch of the aorta free from disease, the origin
of the aorta is opposite the sternal articulation
of the cartilage of the fourth rib of the left
side in the male, and the intercostal space
above it in the female; the ascending limb of
the arch, which is behind the middle bone
of the sternum in the greater part of its length,
may be felt pulsating on the right side of the
sternum in the second intercostal space; the
highest part of the transverse portion of the
arch is on a plane with the centre of the sternal
extremities of the first pair of ribs, and about
an inch below the upper margin of the ster-
num: the arch of the aorta terminates oppo-
site the lower edge of the cartilage of the
second rib of the left side.

The thoracic aorta descends in the posterior
mediastinum, and advances from the left side
to the front of the thoracic portion of the spine,
crossing in its course the left intercostal veins,
and the left vena azygos when that vein exists ; in
front it is covered by the left bronchus, the pos-
terior surface of the pericardium, the lower ex-
tremity of the esophagus, and the left stomachic
cord of the par vagum ; on the right side it is
bounded by the cesophagus, thoracic duct, and
vena azygos ; on the left side it is covered by
the pleura, and in contact with the internal
surface of the left lung, and at its lower extremity
the left splanchnic nerve comes into contact
with it, and most frequently accompanies it
through the diaphragm.

The abdominal aorta, which enters the abdo-
men between the crura of the diaphragm, des-
cends along the front of the abdominal ver-
tebrz and the left lumbar veins; it is covered
in front by the solar plexus of nerves, the
stomach, pancreas, transverse portion of the
duodenum, the splenic and left renal veins, the
small intestine, and the root of the mesentery ;
on the right side it is bounded by the abdomi-
nal vena cava, and the commencement of the
thoracic duct, and on the left it is covered by
the peritoneum going to form the left layer
of the mesentery. ‘The termination of the aorta
in the common iliacs and the middle sacral
arteries is a little below the level of the um-
bilicus.

A remarkable deviation from the cylindrical
form, which is one of the general characteristics
of the arterial system, is observable in two parts
of the arch of the aorta; the first of these occurs at
the commencement of this vessel in form of three
dilatations corresponding to the semilunar flaps
already described ; they were first pointed out
by Valsalva, and have received the name of the
lesser sinuses of the aorta; they exist at all
periods of life, and increase in size with years ;

the other deviation from the cylindrical form is.

a dilatation on the right side of the ascending
limb of the arch at its junction with the trans-
verse portion ; this dilatation, which does not
exist in the foetus, grows larger as life advances,
and sepa to be produced by the impulse
of the blood striking against this part of the
aorta at each successive systole of the left
ventricle. The aorta in the succeeding part of

its course gradually grows smaller in-a degree:

189

proportionate to the size of the branches it
gives off.

The thickness of the aorta is proportionally
less than that of its branches; it is thinner at its
commencement than in the arch, in which part,
according to Haller, it is thicker by an eighth
on the convex than on the concave side; it
gradually diminishes in thickness as it descends
through the thorax and abdomen, but its power
of resisting distention instead of being dimi-
nished in an equal degree was found by Win-
tringham to be greater at its lower part than
near the heart.*

The structure of the aorta is the same as
that of the rest of the arterial system in general ;
its external tunic, however, is slighter than that
of all other arteries except those of the brain,
it is weaker the nearer it is examined to the
origin of the aorta ; it is strengthened near the
heart by the covering which the serous layer of
the pericardium gives to the aorta, and by an
expansion from the fibrous layer of that mem-
brane, which is lost on the transverse portion of

_thearch. The cellular sheath of the aorta in

which the soft fat around its origin is deposited,
becomes so fine where the vessel is passing out
of the pericardium as to lead some anatomists
to deny its existence in this situation ; it becomes
more evident in the course of the descending
aorta through the mediastinum, and is still
more considerable around the abdominal aorta,
where it is usually loaded with a considerable
quantity of adipose substance.

The branches which arise immediately from
the aorta may be divided into orders, according
to the degree of remoteness or the relative size
and importance of the parts which they supply
with blood ; first, the branches which convey
blood to the two extremities of the trunk and
the limbs attached to them; these arteries,
which are of considerable size, are the arteria
innominata, the leftc arotid and left subclavian,
which, arising from the transverse portion of
the arch, are distributed to the head, neck, and
upper extremities, and the primitive iliac arte-
ries which arise from the lower part of the
abdominal aorta supplying the pelvis and the
lower extremities. 2nd order.—Branches some-
what smaller going to the thoracic and abdomi-
nal viscera and the parietes of the chest and
abdomen ; the coronary arteries which supply
the heart arise from the aorta immediately after
its origin; the bronchial arteries which supply
the substance of the lungs, and the intercostal
arteries supplying the parietes of the chest
arise from the thoracic aorta; the cceliac, su-
perior and inferior mesenteric, which supply
the digestive organs; the renal arteries which
supply the kidnies; the spermatic going to the
organs of generation, the inferior phrenic sup-
plying the diaphragm, and the lumbar arteries
going to the parietes of the abdomen and lum-
bar region of the spine, are the vessels of this
order which arise from the abdominal portion
of the aorta. 3rd order.—Branches of much
smaller size are sent from the aorta to se-

* Experimental Inquiry on some parts of the
Animal Structure. London, 1740,

190

condary parts which lie in its vicinity, as the
thymus, the pericardium, the esophagus, the
renal capsules, ureters, &c. 4th order.—Small
arterial twigs lost in the neighbouring cellular
substance, lymphatic glands, and in the coats
of the aorta itself.

Development. — The aorta appears to be
formed in the feetus prior to the heart and sub-
sequently to the system of the vena porta, with
which, according to Baer, Rathke, and Meckel,
it is connected by a small dilatation described by
Dr. Allen Thomson* as a curved tube, which is
the rudiment of the heart. (SeeOvum.) Whilst
the heart has but a single ventricle, the aorta and
the pulmonary artery form a common trunk,
which afterwards becomes divided by the de-
delopment of the contiguous portions of the
circumference of both vessels; during the
remaining periods of intra-uterine life, and

for a short time after birth, the pulmonary.

artery communicates with the aorta by the duc-
tus arteriosus, which appears as a continuation
of the trunk of the pulmonary artery opening
into the concavity of the arch of the aorta at its
termination. The ductus arteriosus becomes
impervious soon after birth, and having under-
gone a process of complete obliteration, is finally
concerted into a ligamentous cord. The size
of the arch of the aorta is less in proportion in
the foetus than in the adult, whilst the thoracic
aorta is larger, being increased in size below
the ductus arteriosus. The arch lies closer to
the spine in the foetus in consequence of the tra-
chea and bronchi behind it being so much less
developed than in the adult, and the thymus
which is between it and the sternum being
so much larger during fcetal life. In old age
the curvature of the arch of the aorta is much
greater in consequence of the great sinus having
increased considerably in size. '

Anomalies——The aorta presents occasional
varieties or anomalies in the mode of its origin,
its course, termination, and the number and
situation of its branches. It is an interesting
fact, that almost every irregularity hitherto
observed in the course and branching of the
aorta in the human subject, represents the dis-
position which that vessel constantly exhibits
in some of the inferior animals. The anomaly
of the aorta arising from both ventricles, and
causing that condition called cyanosis, will be
more properly considered in the article Heart.
The following anomalies of the course of the
aorta have been recorded by anatomists :—

ist. The aorta sometimes divides imme-
diately after its origin into a right and left
trunk, which, after having each given off the
arteries of one side of the head and one upper
extremity, join to form the descending aorta.
Malacarnet has described a remarkable case
of this anomaly; the aorta was of an oval
form at its origin, its greater diameter being
to its lesser in the proportion of three to two,
it had five sigmoid valves in its interior, it
divided immediately after its origin into a right

'* Vide Edinburgh New Philosophical Journal,
by Dr. Jameson, for October, 1830.
“¢ Osservazioni in Chirurgia. Torino, 1784.

AORTA.

and left trunk, from each of which arose a_
subclavian, an external and an internal carotid:
after the two trunks had run for a space of
four inches distinct, they joined to form the
descending aorta. Hommel, a Norwegian ana- —
tomist,* relates a case in which the transverse
portion of the arch of the aorta divided into
two trunks, one of which passed before and
the other behind the trachea, after which they
joined to form the descending aorta, having
encircled the trachea with a sort of ring: this
anomalous division of the arch of the aorta is
the more remarkable as it approaches the con-
dition of the vessel which is constant in all
known reptiles. 2d. The arch of the aorta is
sometimes absent, in consequence of the vessel
dividing, immediately after its origin, into two
great trunks, one of which gives off the arte-
ries of the head and upper extremities, whilst
the other becomes the descending aorta.t This
distribution is similar to that in the horse,
rhinoceros, and other pachydermata, in the
ruminantia, and some of the rodentia. 3rd.
Varieties in the course of the arch sometimes,
although rarely, occur, as, for instance, when
the arch of the aorta, instead of crossing to the
left in the usual manner, curves over the right
bronchus, and gets to the right side of the
spine, whence it either immediately crosses
behind the trachea and esophagus to the left,
or continues its course along the right side of
the spine to the lower part of the thorax;
in cases of complete transposition of the vis-
cera, where the heart is in the right side of the
chest, the arch of the aorta is also reversed,
in which case its thoracic portion descends
along the right side of the spine.{ Instances
are recorded in which the descending aorta,
a little below its arch, was very much con-
tracted in its area or even completely obliterated
for a certain distance, below which it resumed
its full size: the circulation in these cases was
carried on by the anastomosing of large col-
lateral branches arising above and below the
constricted or obliterated part.§
Anomalies of the branches of the aorta are
more frequent: according to Meckel the
branches arising from the arch deviate from
the normal condition in one person out of
every eight.|| The branches arising from the
arch of the aorta present three kinds of ano-
maly, which, as to their frequency, occur in the
following order: ist, an increase in their num-
ber; 2d, a diminution; and 3d, an anomaly
in the identity or order of the branches arising
from this part without any increase or diminu-
tion of their number. In anomalies of the first

~~ 2.

* Comm. Noric. ann. 1737.
+ Vide Abhandlungen des Josephinischen Medi-
cinisch-Chirurgischen Akademie. Band, i. S. 271.
Taf. 6. Wien. 1787. a
¢ Meckel Handbuch der Menschlichen Anatomie. _
Band iii, Halle and Berlin, 1817, Abernethy in
Phil. Trans. 1793. fae
§ Desault in Journal de Chirurgie, tom. i
Dr. Goodison in Dublin Hosp. Reports. Brasdor
Recueil Periodique de la Société de Médecine. —
Paris, tom. iii. +
Handbuch der Menschlichen Anatomie. —
Band iii, Halle and Berlin, 1817. .

s

AORTA.

kind, the number of branches is most fre-
quently increased to four, by the left vertebral
arising from the arch between the left carotid
and left subclavian, as in the phoca vitulina ;
next to this in frequency is the instance of the
inferior thyroid arising from the arch between
the innominata and left carotid, then the in-
ternal mammary, and, lastly, the most un-
usual is the thymic artery : it is more unusual
to find the number of branches coming from
the arch increased to four, in consequence of
the innominata being absent, the right carotid
and right subclavian arising separately ; in such
a distribution the right subclavian’ most fre-
quently arises from the left extremity of the
arch after the left subclavian; it may, how-
ever, be the first branch of the arch to the right,
or it may arise between the two carotids, or,
as more rarely happens, between the left
carotid and left subclavian. The number of
branches arising from the arch will be in-
creased to five or upwards, when two or more
of the above-mentioned anomalous branches
arise from it at the same time. Of the second
kind of anomaly, or that by diminution of the
number of branches, the most frequent is
where these are reduced to two, of which
there occur the following varieties: a. the in-
nominata sometimes gives off the left carotid
as an additional branch, and the left subcla-
vian arises separately, as in many quadrumana,
several of the carnivora, as the lion, cat, dog,
weazel, several rodentia, &c.; 6. sometimes there
are two arterie innominate, each dividing in
a symmetrical manner into the subclavian and
carotid of its own side, as in cheiroptera and
the dolphin; c. sometimes when the arch gives
off but two trunks, one of them divides into
the two carotids, and the other into the sub-
clavians; d. the right subclavian may arise
distinct, and a common trunk give off the two
carotids and left subclavian; the origin of a
single trunk from the arch of the aorta sup-
plying the arteries of the head and upper
extremities is equivalent to a division of the
aorta into an ascending and descending trunk,
already noticed. The third kind of anomaly
partakes of the characters of the two pre-
ceding, although the number of branches is
the same as in the normal state: its varieties
are, a, the left vertebral arising from the arch,
whilst the left carotid comes from the inno-
Minata; 6, the two carotids may arise from a
common trunk between the origins of the right
and left subclavians, as in the elephant; c,
the right subclavian and right carotid may
arise as distinct branches, whilst the left carotid
and left subclavian come from a common
trunk, forming a complete inversion of the
usual order; d, the left carotid may arise from
the innominata, whilst the right carotid comes
from the part of the arch in the situation usu-
ally occupied by the origin of the left carotid.
Anomalies of the branches of the descending
aorta are less frequent; the following are among
the more remarkable: a, the celiac and dia-
phragmatic may arise above the diaphragm ;
one or both of the diaphragmatics may be
given off by the celiac; sometimes the cceliac

191

and superior mesenteric arise by a common
trunk as in the tortoise; sometimes there are
two or more renal arteries on one or both sides,
and sometimes the primitive iliacs are given
off much higher than usual, in which case they
are sometimes connected by a cross branch
before they divide into the external and in-
ternal iliacs: it sometimes happens, when the
iliacs are given off higher than usual, that the
inferior mesenteric arises from the left of
them.

The diseased conditions of the aorta are
described in the articles ArTERY and Heart.
The aorta, as Beclard remarks,* is more sub-
ject than any other artery to the ovoid dila-
tation in its ascending, and the lateral dila-
tation in its descending portion ; it is also very
subject to osseous or calcareous deposits, to
fissures and ulcerations, to tubercles and small
abscesses in its parietes, and to aneurism.
Wounds of the aorta are constantly mortal.
Laennec has observed a particular lesion of
this vessel; it was a fissure of the internal
and middle coats, from which the external tunic
was extensively separated by a quantity of
blood which had been effused between it and
the middle tunic. The late Mr. Shekelton has
described, in the Dublin Hospital Reports,
a form of aneurism of the lower part of the
abdominal aorta, in which the blood forced its
way through the internal and middle coats,
dissected the middle from the external for the
space of four inches, and then burst into a lower
part of the canal of the artery, forming a new
channel which eventually superseded the
old one, which the pressure of the tumour
obliterated.

Granular excrescences are sometimes formed
on the valves of the aorta, which Corvisart
conjectured to be of venereal origin. The in-
ternal tunic of the aorta sometimes presents a
red appearance, not peculiar, however, to this
vessel, and occurring in certain forms of fever.
Obliteration or constriction of the aorta is a
condition rarely met with; its existence may
be traced either to pressure on the vessel from
without, morbid thickening of its coats, or the
formation of coagula internally; this latter
occurrence being most usually a consequence
of the spontaneous cure of aneurism.

Aneurisms of the aorta produce various
effects on surrounding parts; thus the heart,
lungs, trachea, cesophagus, pulmonary artery,
large veins, thoracic duct, and the various
organs in the abdomen placed in their vicinity,
may suffer derangement of their functions,
displacement, atrophy or partial destruction,
according to the degree of pressure to which
they are subjected.

Aneurisms occurring in the ascending por-
tion of the aorta, which is within the pericar-
dium, are often attended during life by many
symptoms very similar to those of disease of the
heart itself, while their pressure may produce
a diminution of the calibre of the pulmonary
artery, obstruct the free passage of the blood
through the vena cava superior, and even in-

* Dictionnaire de Médecine, art. Aorte.

192. ¢ AORTA. -

terfere with the full distension of the auricles.
Aneurisms of the transverse portion of the
aorta, when directed forwards, usually project
at the right side of the sternum about the
second intercostal space: when the sac extends
upwards towards the neck, it frequently be-
comes a matter of extreme difficulty to dis
tinguish an aneurism of the aorta from an
aneurism of the innominata or some other
large arterial trunk in the neighbourhood ;
cases are on record, where the pressure of such
aneurisms of the aorta caused obliteration of
the subclavian and common carotid. When
aneurisms extend backwards, they produce a
variety of effects, interfering with respiration
and deglutition from their pressure on the
trachea and cesophagus, sometimes producing
obliteration of the thoracic duct. The pres-
sure produced by aneurisms of the thoracic
and abdominal aorta occasionally cause ab-
sorption of the bodies of the vertebra, and give
rise to an appearance not very dissimilar to
- that produced by caries.

Aneurisms of the arch of the aorta do not
so often terminate fatally by making their way
through the anterior parietes of the chest, and
opening externally as by bursting internally :
when they occur in that part of the arch of the
aorta covered by the pericardium, they most
usually burst into the sac of that membrane;
cases are recorded in which aneurisms of the
aorta have burst into the pulmonary artery,*
or, taking a direction backwards, have opened
into the trachea, esophagus, or the substance
of the lungs. Aneurisms of the thoracic por-
tion of the aorta sometimes burst into the left
pleura, sometimes into the posterior medi-
astinum: they have been known to point at the
left side of the spine, after having caused ab-
sorption of the heads of the ribs and sides
of the bodies of the vertebre. In two cases
observed by Laennec and Mr. Chandler, aneu-
rism of the thoracic aorta burst into the spinal
canal. Aneurisms of the abdominal aorta
most usually burst into the cellular tissue of
the lumbar regions behind the peritoneum,
seldom into the sac of that membrane. An
aneurism of the abdominal aorta has been
observed to make its way backwards by the
side of the spine, and point in such a situation
as to have been at first mistaken for lumbar
abscess.

Branches of the aorta. 1. Branches arising
Srom the arch—F¥rom the arch of the aorta
five branches are given off; two from its com-
mencement, the coronary arteries, and three
vessels of considerable size (fig. 78 a bc ), from
the upper part of its transverse portion to
supply the head and the upper extremities.
The coronary arteries of the heart or the car-
diac arteries arise from the aorta close to its
origin, and immediately above the free borders
of the sigmoid valves; they are usually two in
number, one for each ventricle.

The right, anterior or inferior coronary
artery is often larger, seldom smaller than the

* Dr. Wells in Trans. of a Society for Improve-
ment of Medical and Surgical Knowledge, vol. iii.

A B, arch of the aorta.

-C, thoracic aorta.

D, abdominal aorta.

E, common iliac artery.

g, middle sacral artery.
left; it arises from the anterior side of the’
aorta above the anterior sigmoid valve, coming
out from between the roots of the aorta and
pulmonary artery, it passes downwards and to
the right side in the groove between the right
auricle and ventricle, turns round the right edge
of the heart until it reaches the groove of the
septum on the inferior surface of that organ,
when it changes its direction, coursing along
that groove until it arrives at the apex of the
heart, where it anastomoses with the left coro-
nary artery; in its course it gives off to the
right and left many tortuous branches arising
nearly at right angles, the right branches are
smaller and go to the right auricle, the left are
larger and belong to the right ventricle, which
they traverse in a longitudinal direction to-
wards its apex. From the origin of the right
coronary artery two small branches are given
off, one to the commencement of the pul-
monary artery and the surrounding fat, which
anastomoses behind the pulmonary artery
with a branch of the left coronary; the se-
cond branch anastomoses with the bronchial
arteries.

The left posterior or superior coronary —
artery arises between the left auricle and the —
posterior surface of the pulmonary artery, de- ._

a aT st

AORTA.

scending to the left between the left auricle
and pulmonary artery, and, having reached the
groove at the base of the heart, dividing into
two or three branches; one anterior longitu-
dinal descends along the anterior groove of the
septum to the apex of the heart, where it anas-
tomoses with the termination of the right
coronary artery, with which it holds frequent
communication by branches which it sends
___ over the anterior surface of the right ventricle,
___ while it sends some large branches to the left
ventricle; this branch at its commencement
gives small twigs to the aorta and pulmonary
artery. The second branch of the left coronary
__ artery covered by the great coronary vein passes
from right to left in the groove between the
left auricle and ventricle, to both of which it
_ gives many branches, turns round the left
rder of the heart, changes its direction, and
descends by the side of the right coronary
artery to the apex; the third branch sinks into
the substance of the septum and continues its
course to the apex; this branch sometimes
arises directly from the aorta ; in this latter case,
of course, there will be three coronary arteries
arising from the aorta; Meckel has once seen
four; the supernumerary coronary artery does
not arise above any particular valve, but usually
close to the origin of one of the normal
branches. It is rare to find but one coronary
artery in the human subject, which corresponds,
according to Camper, with the normal con-
formation in the elephant. The three large
branches arising from the transverse portion
_ of the arch of the aorta and sent to the head
and upper extremities, will be described in a
separate article.
. I. Branches of the thoracic aorta.—These
tay be divided into anterior and lateral. The
anterior branches are, the bronchial, esophageal,
_ and posterior mediastinal. The lateral are the
_ _tferior or aortic intercostal arteries. The
bronchial arteries are usually two in number,
one for each lung; sometimes, however, there
are two for each lung, and sometimes the right
and left bronchial arise from a common trunk,

Se ees ee?) a, oO!

' which usually springs from the first aortic in-
tercostal of the right side.
The right bronchial artery most usually arises
from the first aortic intercostal artery of the
_ tight side, which supplies it after having arrived
at the right side of the spinal column behind
___ the esophagus, sometimes it comes direct from
_ the aorta; it proceeds in a tortuous course under
___ the right bronchus, to the root of the right lung,
as having given small branches to the ceso-
_ phagus, the pleura, the back part of the peri-
__ ¢ardium and the bronchial glands.
___ The left bronchial artery arises immediately
_ from the aorta and passes in front of the cso-
__ PAagus to the left bronchus, to the posterior
_ side of which it attaches itself. Both bronchial

egg are similarly distributed through the

dividing with the bronchi, along each
branch of which they send two or Gee tarins
_ us twigs. The relation of the bronchial arte-
_ fies to the other vessels of the lungs will be
‘More particularly noticed in the article Lune.

The esophageal arteries vary in number from
VOL. 1,

193

two to seven: they are inferior to the bronchial
in size: they arise from the front of the thoracic
aorta, and are distributed to the esophagus, on
which they anastomose freely with descending
branches of the inferior thyroid from above, in
the middle of the esophagus with the bronchial,
and below with branches of the phrenic and
coronary artery of the stomach.

The posterior mediastinal arteries are nume-
rous and small; they send branches to the
cesophagus, thoracic aorta, thoracic duct, ab-
sorbents, and cellular membrane of the pos-
terior mediastinum, anastomosing with the
bronchial, cesophageal, and some branches of
the right thoracic intercostal arteries.

Inferior or aortic intercostal arteries—Of
the eleven intercostal spaces the two superior are
mostly supplied with arteries from the superior
intercostal branch of the subclavian; and as the
first aortic intercostal artery frequently supplies
the third and fourth intercostal spaces, we often
meet with but eight pairs of intercostal arieries
coming immediately from the aorta (fiy.78, d ).
The first right aortic intercostal is usually the
largest of the series in consequence of giving
origin to the right bronchial ; the size of the inter-
costal arteries diminishes in general from above
downwards. All the intercostal arteries arise
rather from the posterior part of the aorta, those
of opposite sides arising very near each other,
and sometimes springing from a common trunk.
At first they descend obliquely on the vertebral
column, at an acute angle to the trunk of the
aorta. The right intercostal arteries are longer
than the left, in consequence of the position of
the thoracic aorta on the left side of the spine.
Each artery is lodged at first in a groove on
the side of the body of each vertebra, enters the
intercostal space passing behind the ganglia of
the sympathetic nerve, and immediately divides
into two branches, one posterior or dorsal, the
other anterior or intercostal. The posterior
branch passes backwards through a space above
the neck of each rib and below the tranverse
process of the superior of the two vertebre, with
which the head of the rib is articulated ; it
gives some branches to the bodies of the ver-
tebre, and in passing the intervertebral hole
it sends branches inwards to the spinal cord,
which anastomose with the spinal arteries. The
continuation of the vessel is distributed to the
longissimus dorsi, sacro-lumbalis, and other
muscles along the side of the spine, as well as
to the integuments of the back. The ante-
rior or proper intercostal branch is usually
larger than the posterior, and traverses the
intercostal space. At first it is situated be-
tween the pleura and external intercostal
muscle, it dhoniy divides into two smaller
branches, a superior and an inferior, which get
between the two layers of intercostal muscles.
The inferior branch, usually the smaller, runs
forwards along the superior border of the in-
ferior rib, and passes obliquely over its surface
to the periosteum covering it. The superior
branch, larger than the former, enters a groove
in the lower edge of the superior rib, about its
angle, in company with the intercostal nerve,

and passes forwards between the two layers of
)

194

intercostal muscles, towards the junction of the
rib with its cartilage, where it descends from
the rib towards the middle of the intercostal
space, and there anastomoses with the anterior
intercostal arteries sent off from the internal
mammary. Besides supplying the intercostal
muscles, pleura, and ribs, the intercostal arteries
give several branches, which pierce the external
layer of intercostal muscles, and carry blood
to the muscles and integuments covering the
thorax. The lower intercostalsalso send branches
_to the abdominal muscles, diaphragm, and
quadratus lumborum, which freely anastomose
with the internal mammary, epigastric, phrenic,
lumbar, and circumflex iliac arteries.

Anastomoses.—The intercostal arteries have
a chain of anastomoses with each other by
communicating branches which cross the heads
of the ribs. By this means the superior freely
communicate with the subclavian by its inter-
costal artery. Inferiorly, their anastomosis
with the phrenic, circumflex ilii, and lumbar
arteries, is equally free; internally they anasto-
mose with the arteries of the spinal cord, and
in front with the internal mammary and epi-
gastric.

III. Branches of the abdominal aorta.—
They may be divided into anterior and lateral.
The anterior branches are, the inferior phrenic,
celiac, superior and inferior mesenteric.

Phrenic arteries. —The phrenic arteries are
two in number; they arise from the aorta im-
mediately after its entrance into the abdomen,
generally distinct, sometimes from a common
trunk, and occasionally one or both arise from
the cceliac artery, or one of its branches. Each
phrenic artery passes outwards in front of the
crus of the diaphragm, and along the upper
edge of the renal capsule of its own side. The
right artery passes behind the vena cava, and
the left behind the esophagus. They run on
the abdominal surface of the diaphragm, and
at the posterior edge of the cordiform tendon
each vessel divides into an external and an
anterior branch. The external branch supplies
the fleshy substance of the ala ofthe diaphragm,
and sends several branches towards the external
attachments of that muscle which anastomose
with the lower intercostal and lumbar arteries ;
while the anterior branch, coursing round the
margin of the cordiform tendon, supplies the
anterior part of the diaphragm, and anastomoses
with its fellow of the opposite side, behind the
ensiform cartilage, sending forwards branches
to anastomose with the internal mammary.

Minute branches are given off by the phrenic
arteries near their origins to the semilunar
ganglia and renal capsules: a small twig from
the right phrenic ascends along the vena cava
through the diaphragm to anastomose with the
comes nervi phrenici of the internal mammary.
Another similar twig, given to the esophagus
by the left phrenic, while passing behind. that
tube, anastomoses with the middle cesophageal
arteries.

_ The celiac artery, called, also, celiac axis,
is one of the largest and shortest of the vessels
given off by the abdominal aorta. It generally
arises from the aorta, between the crura of the

AORTA.

diaphragm opposite the junction of the last
dorsal and first abdominal vertebra, having the =
renal capsules and semilunar ganglia on either =
side of it, with the lobulus Spigelii to the right,
the cardiac orifice of the stomach to the left,
the superior border of the pancreas inferiorly,
and the stomach and lesser omentum in front >
it is closely embraced by branches of the solar
plexus.

The cceliac artery, which is often scarcely
half an inch in length, immediately divides into
three branches, the gastric or coronaria superior
ventriculi, the hepatic, and the splenic, which.
constitute the tripod of Haller. Sometimes the
celiac axis gives off the phrenic and superior
capsular.

Coronary artery of the stomach.—The coro-
nary artery is the smallest of the three branches
furnished by the trunk of the celiac; it some-
times arises from the aorta itself. Passing
upwards, forwards, and to the left, it arrives
at the cardiac orifice of the stomach, from
which it proceeds forwards and to the right,
following the direction of the lesser arch of
the stomach until it arrives near the pylorus,
where it anastomoses with the pyloric branch
of the hepatic. When the coronary artery has
arrived at the cardiac orifice of the stomach, it
sends one or more branches upwards along the
cesophagus which supply that part with blood,
and anastomose with the cesophageal arteries
from the thoracic aorta: it then sends branches
round the cardiac orifice, which nearly encircle
that part, and ramify over the great extremity of
the stomach, where they anastomose with the vasa
brevia of the splenic. In its course along the
lesser arch of the stomach the coronary sends
many branches over both surfaces of that viscus,
which anastomose with each other and with
the right and left gastro-epiploic. The ter-
minal branch of the coronary which ends at
the pylorus is sometimes called superior pyloric.
Sometimes the coronary artery gives off the
right hepatic immediately before reaching the
cardiac orifice of the stomach.

The hepatic artery passes forwards and to
the right under the lobulus Spigelii to the neck
of the gall-bladder. In this part of its course
it gives a few twigs to the gastro-hepatic omen-
tum and the inferior surface of the liver; when
it reaches the pylorus, it gives two considerable
branches called the pyloric and the right gastro-
epiploic. The pyloric passes from right to left
along the lesser arch of the stomach, where it
meets the coronary with which it anastomoses, —
sending several branches over the anterior and —
posterior surfaces of the stomach to anastomose ~
with the right gastro-epiploic artery. The right
gastro-epiploic artery, much larger than the
pyloric, arises after that vessel ; it passes down-
wards behind the pylorus, and arrives at the
greater arch of the stomach, along which It
courses from right to left and anastomoses
with the left gastro-epiploic. While passing
behind the pylorus, it gives several branches te
the pancreas and duodenum, one of which,
somewhat larger than the rest, called pancreatico:
duodenalis, lies concealed between the duo-
denum and head of the pancreas, and anas

ca

Fk im oH

:

AORTA.

moses with the branches which the pancreas
receives from the superior mesenteric. As the
gastro-epiploic artery courses along the greater
arch of the stomach, it gives off numerous
branches, some of which ascend on the anterior
and posterior surfaces of the stomach, and
anastomose with the coronary and pyloric;
others descend in the anterior layer of the great
omentum: some branches from these ascend
in the posterior layer of this fold of membrane
until they reach the arch of the colon, where
they anastomose with the colic branches of the
superior mesenteric.

After having given off these branches, the
hepatic artery ascends towards the right within
the capsule of Glisson, in front of the vena
porta, and to the left of the ductus communis
choledochus. Having reached the transverse
fissure of the liver, it divides into the right and
ft hepatic arteries which enter the liver by

ivisions corresponding to those of the vena
porta, the right branch having previously given
off the cystic artery, which arises opposite the
junction of the cystic and common hepatic
ducts, attaches itself to the neck of the gall-
bladder, and soon divides into two branches,
one of which ramifies over the inferior surface
of that reservoir, while the other sinks between
the liver and the gall-bladder. For further
a relating to the hepatic artery vide

IVER.

The splenic is the largest of the three branches
of the celiac. Immediately after its origin it
oti with numerous contortions to the left,

hind the stomach and along the superior
border of the pancreas to the fissure of the
spleen. In this course if gives off pancreatic
branches (pancreatice magne et parve ), which
anastomose with the pancreatic branches of
the right gastro-epiploic. It gives a large
branch, the left gastro-epiploic, which some-
times arises from one of the branches in which
the splenic terminates. This branch passes
onwards to the left until it reaches the greater
arch of the stomach, along which it descends,
passes to the right until it meets the right
gastro-epiploic, with which it anastomoses.
In its course it gives off, like the right gastro-
epiploic, superior branches, which pass over
the anterior and posterior surfaces of the sto-
mach to anastomose with the branches of the
coronary and inferior branches which descend
in the great omentum, where they have a simi-
lar distribution with the descending branches
of the right gastro-epiploic : near the fissure of
the spleen, the splenic artery divides into five
or six branches, which anastomose by arches,
and enter the substance of that organ. Before
entering the substance of the spleen these
branches give off large vessels, called vasa
brevia, which bend to the right, and are dis-
tributed to the great extremity of the stomach,
Spreading over its anterior and posterior sur-
faces, where they anastomose with branches of
the coronary and right gastro-epiploic.

The superior mesenteric artery, often larger
than the ceeliac, arises from the aorta imme-
diately after the celiac ; sometimes from a trunk
common to both vessels, as in the tortoise. This

195.

artery is at first concealed by the pancreas, it
descends perpendicularly behind that gland
and crossing the termination of the duodenum
arrives at the root of the mesentery, between
the two layers of which it descends. In the
middle of this fold of the peritoneum it forms
a considerable curve, the convexity of which is to
the left, and directs its course towards the ter-
mination of the small intestine im the right iliac
region, forming near its termination a second
curve, the concavity of which is to the left.
Near its origin this artery gives some branches
to the duodenum and pancreas, by means of
which it anastomoses with the branches of the
hepatic and splenic sent to these organs: in the
mesentery it sends off from its left side the
arteries of the small intestines, and from its
right the arteries which it supplies to the great
intestine.

Arteries of the small intestines.—These arise
from the left side of the superior mesenteric,
varying in number from fifteen to twenty ; the
superior are longer and larger, those which
succeed them appear to diminish progressively
in length and size, they all advance between
the two layers of the mesentery to the concave
side of the intestine; at a certain distance from
their origin they divide into secondary branches
which diverge from each other at acute angles ;
these secondary branches subdivide into still
smaller branches, which, diverging in a similar
manner, form arches of anastomoses with cor-
responding branches of the adjoining arteries ;
the .convexities of these arches are all turned
towards the intestine, and from them numerous
branches arise, which, by dividing and anasto-
mosing like the larger trunks, form a second
series of smaller arches ; other branches arising
from the convexities of these arches divide and
anastomose to form still smaller and more
numerous arches; thus we have three, some-
times four, and occasionally five series of
arches, formed by the subdivisions of these
arteries before they reach the intestine, and
presenting in the mesentery a network with
large meshes. From the convexities of the
extreme arches which form the outer border of
this network, thousands of small arteries pass
in a straight direction to the tube of the intes-
tine ; these form two series, an anterior and a
posterior, which apply themselves to the oppo-
site surfaces of the intestine, and anastomose
with each other on its convex border. The
detailed description of their further distribution
will come under consideration in the article
InTEsTINAL CANAL.

Colic arteries.——-The superior mesenteric
sends off three, sometimes only two, branches
from its concavity, called right colic arteries, dis-
tinguished as superior or colica media, middle or
colica dextra, and inferior or ileo-colic ; when
there are but two, the superior and middle form
but a single trunk; the inferior is generally
distinct.

The right superior colic or colica media arises
a few inches distant from the origin of the supe-
rior mesenteric; it passes forwards between the
layers of the meso-colon towards the middle of
the transverse colon, and divides into a right

oO 2

196

and left branch; the right follows the right
part of the transverse colon, and anastomoses
with the superior branch of the colica dextra ;
the left branch follows the left portion of the
transverse colon, and communicates with the
left colic branch of the inferior mesenteric
artery.

The colica dextra or middle right colic artery
arises close to the colica media, sometimes from
a trunk common to both, and sometimes from
the ileo-colic. After its origin it passes for-
wards, upwards, and to the right in the meso-
colon towards the ascending colon, and divides
into two branches ;. one superior ascends to
anastomose with the right branch of the colica
media, the other descends along the concavity
of the ascending colon, and communicates with
the ascending branch of the ileo-colic.

The ileo-colic, cecal, or inferior right colic
passes downwards, and to the right towards the
cecum, and then divides into three branches ;
the first ascends in the meso-colon, and anas-
tomoses with the descending branch of the
colica dextra; the second communicates in the
mesentery with the termination of the superior
mesenteric; and the third, arising in the angle
between the two preceding, passes behind the
junction of the ileum with the cecum : at this
place it gives off a branch which forms a small
arch in the mesentery of the vermiform appen-
dix, and then divides into two branches, one
of which passes upwards on the colon, and the
other descends on the cecum. The colic arte-
ries, by their anastomoses with each other,
form arches, from the convexities of which,
turned towards the intestine, numerous branches
arise ; each of these again divides into two,
which with the contiguous vessels form smaller
arches, and straight branches finally arise from
the ultimate arches, which, passing on either
side of the intestine, include it between them,
and anastomose on its convex edge.

In the foetus we have the omphalo-mesen-
teric artery arising from the superior mesen-
teric ; this vessel, which passes along the um-
bilical cord to the vesicula alba, becomes
obliterated towards the end of the second
month of gestation.

The inferior mesenteric artery arises from the
front of the aorta to its left side, at about an
inch or an inch and a half above the origins of
the primitive iliacs ; it sometimes arises from the
left primitive iliac, especially when the aorta
has divided higher than usual ; instances of the
absence of this artery are very rare, but interest-
ing as presenting an example of the normal
condition in birds and reptiles, in which the
inferior mesenteric artery is much reduced in
size or entirely absent.

The inferior mesenteric artery runs obliquely
downwards and to the left, and gets between
the layers of the left iliac meso-colon, where it
divides into many branches, distributed to the
left portion, and sigmoid flexure of the colon
and the rectum; the superior branches are dis-
tributed to the descending portion and sigmoid
flexure of the colon, and are called left colic
arteries, while the lower branches go to the
rectum under the name of superior hemor-

AORTA.

rhoidal arteries. The left colic arteries are
three in number, the superior, middle, and in-

JSerior. The superior left colic is the largest

of the three; it arises from the inferior mesen-
teric immediately after its origin, passes trans-
versely to the left, and divides near the left
lumbar colon into two branches, one of which
ascends to the transverse meso-colon, and
anastomoses with the colica media of the supe-
rior mesenteric; the other branch descends
towards the left iliac meso-colon, where it
anastomoses with the ascending branch of the
middle left colic.

The middle left colic is sometimes a branch
of the preceding. It divides into two branches;
one ascends along the left colon, and anas-
tomoses with the descending branch of the left
superior colic; the other, inferior, smaller com-
municates with the ascending branch of the left
inferior colic.

The inferior left colic goes to the sigmoid
flexure of the colon, and soon divides into two
branches; one superior anastomoses by an arch
with the descending branch of the preceding,
and the other inferior meets a branch of the
hemorrhoidal in the meso-rectum. They are
distributed to the intestine in a similar manner
with the branches of the right colic arteries, as
already described.

When the inferior mesenteric has given off
the colic arteries, it diminishes, takes a perpen- |
dicular direction, and reaches the posteror sur- i
face of the rectum lodged between the layersofthe
meso-rectum, here it takes the name of superior
hemorrhoidal artery. It soon divides into two
branches, a right and left, which apply them-
selves to the sides of the rectum, sending
branches backwards and forwards round that
intestine, by which they communicate with each
other, and anastomose below with the middle q
and inferior hemorrhoidal arteries; some
branches anastomose with the lateral sacral of
the internal iliac.

The lateral branches of the abdominal aorta
consist of the capsular, renal or emulgent,
spermatic arteries, small twigs to the ureters
and adipose substance in the vicinity of the
aorta, and the four pairs of lumbar arteries. For
an account of the capsular, emulgent, and sper-
matic arteries we must refer to the articles
Rena Capsu ces, Kipney, and TEsticie.

The lumbar arteries are four in number on
each side (fig. 78, f.); they arise from the lateral
and posterior part of the aorta nearly at right
angles, they pass outwards across the middle of
the bodies of the four superior lumbar or abdo-
minal vertebre to the roots of their transverse
processes, covered by the psoas muscle and the
crura of the diaphragm. When the lumbar —
arteries have reached the roots of the transverse _
processes of the lumbar vertebra, they divide
each into two branches, one posterior and the
other anterior. i

The posterior or dorsal branches are smaller
and pass backwards between the transverse —

rocesses of the lumbar vertebra, opposite the —
intervertebral foramina, where they each send a
branch inwards to the spinal cord and cauda
equina ; they then plunge into the substance of —

AORTA. 197

the great sacro-lumbar mass of muscles, in which
they are lost, anastomosing frequently with each
other, and with the dorsal branches of the low-
est intercostal and ileo-lumbar arteries. The
continuations or anterior divisions of the lum-
bar arteries pass outwards between the psoas
and quadratus lumborum muscles, to which they
give small branches, as well as to the diaphragm,
kidney, renal capsule, and surrounding cellular
membrane; they then continue their course
forwards between the layers of the abdominal
muscles, in company with branches of the lum-
bar nerves, and anastomose with the lower in-
tercostals, mammary, epigastric, and circum-
flexa ilii.
The middle sacral artery arises from the back
of the abdominal aorta, immediately above
the origins of the primitive iliacs, from one of
which it arises in some rare cases, it descends
exactly over the middle ofthe anterior surface of
the bodies of the last abdominal vertebra, false
vertebre of the sacrum and os coccygis, lying
close on the surfaces of those bones; the
branches which it gives off are distributed in
a lateral direction; the first is the largest and not
unfrequently is the fifth lumbar artery, the size of
which sometimes exceeds that of the continuation
ot the trunk of the middle sacral itself. This
branch divides into an anterior and a posterior,
the distribution of which is similar to that of
the superior lumbar arteries. Two transverse
branches usually arise from the middle sacral
on the body of each false vertebra ; these pass-
ing outwards give branches to the periosteum
and the substance of the sacrum, anastomose
with branches of the lateral sacral arteries,
and enter the anterior sacral foramina, where
they give some branches to the origins of the
sacral nerves, and emerging from the posterior
sacral foramina are lost in the muscles arising
from the back part of the sacrum; finally, the
middle sacral terminates at the extremity of the
coccyx in small branches, which it sends to the

‘rectum and surrounding fat.

The middle sacral artery is sometimes found
double; in the foetus this artery is propor-
tionally larger than in the adult, especially in

the earlier periods of gestation. In some ani-
_Mals, the size of the middle sacral artery is

scarcely inferior to that of the aorta itself, as
in the cetacea and fishes. In all animals fur-
nished with tails, the size of this artery bears
a constant relation to the size of that member.
Aneurism rarely affects any of the branches
of the aorta above described ; it, however, occa-
sionally occurs in the coeliac or mesenteric arte-
ries, or some of their branches. An interesting
case of aneurism of the hepatic artery unat-
tended by pulsation during life, and which
produced jaundice by pressing on the ductus
communis choledochus, is reported by Dr. Wil-
liam Stokes, in the Dublin Journal of Medical
and Chemical Science, for July 1834. We
once witnessed the dissection of a female aged
forty, under the care of the late Professor Todd,
in the Surgical Hospital of the House of Indus-
uy in Dublin, in whom three distinct aneurisms
large size were found in the epigastric region ;
one of the hepatic artery, which communicated

with that vessel by a longitudinal fissure, and
which had opened into the cavity of the gall-
bladder ; one of the trunk of the coronary artery
of the stomach, and a third of the splenic
artery. A remarkable feature in this case, and
that of Dr. Stokes, was the absence of pulsa-
tion during life, in consequence of which the
nature of the disease was not discovered until
the post-mortem examination ; the above cir-
cumstance may be attributed to the want of
resistance in the surrounding parts, and it is
one which frequently obscures the diagnosis
of abdominal aneurisms.

BIBLIOGRAPHY.—Dict. de Medecine, art. Aorte.
Beclard, Elémens d’anatomie générale, 8vo. Paris,
1823. Wéintringham, Exper. inquiry on some parts
of the animal structure, 8vo. Lond. 1740. A.
Thomson, in Jameson’s New Philosophical Journal
for Oct. 1830. Malacarne, Osserv. in Cirurgia,
2 pte, 8vo. Torino, 1784. Hommel, in Com. Noric.
An 1737. Klintz, in Abhand. d. Joseph. Med.
Chirurg. Akademie, Bd i. 4to. Wien. 1787. Meckel,
Hanbd. d. menschlichen anatomie, 3 Bde 8vo.
Halle and Berl. 1817. ~Abernethy, Phil. Trans.
1793. Desault, in Journal de Chirurgie, t. ii.
Goodison, in Dub. Hosp. Repts. Brasdor, in Ree.
period. de la Société de Médecine, t. iii. 8vo. Paris.
Stokes, in Dublin Journal of Med. and Chem.
Science, 8vo. * * * * Bayer, Pres. Tiedemann,
Diss. de ramis ex arcu aorte prodeuntibus, 4to.
Salzb. 1817. Varieties in the number and origin
of the principal branches of the aorta are signalized
by Tiedemann, (Tabule arteriarum corporis hu-
mani fol. mag. Carolirh. 1827,) in great numbers ;
also by Hunauld (Mem. de Paris 1737 and 1740) ;
Neubauer (De Art. thyrodea ima); Meckel, ( Epist.
ad Haller, iii.) ; Walter (Mem. de Berlin, 1785) .
J. F. Meckel (Tab. anat. pathol. fase. ii. fol. Lips.
1817-26); Haller (Elementa Physiologie, t. ii.) ;
Meckel (Pathol. znatomie, 3 Th. 8vo. Leipz. 1812,
and in Archiv. Bd. vi.); Huber (Acta Helvet.
viii.) ; Loder (Progr. de nonnul. variet. arteriarum,
4to. Jene, 1781); Herold (Diss. exh. obs. quasd.
ad corp. hum. partium struct. Marburge, 1812);
Nevin (Edinb. Med. Comment. Dec. 2, vol. 9);
Ryan (De quarundum arteriar. in corp. hum. dis-
tributione, 8vo. Edinb. 1812); Schoen (De nonnul.
arteriar. ortu et decursu abnormi, 8vo. Hal. 1823) r
Schmiedel (De varietatibus vasor. pler. magni mo-
menti, 4to. Erlang. 1745); Ludwig (Obs. qued.
angiolog. 4to. Lips. 1764) ; Sandifort (De notabil.
vasor. aberrationibus, in Obs. anat.pathol. 4to. Lugd.
Batav. 1774); Koberwein (De vasorum decursu
abnormi ejusque vi, &c. 4to. Viteberg. 1810);
Barkow (Disq. circa originem et decursum arteri-
arum, 4to. Lips. 1829); Otto (Seltene Beobach-
tungen; ii Sammlungen, 4to. Berl. 1816-24; Ejus
Handbuch. d. patholog. anatomie, 8vo. Berl.
1830—Englished by J. South, 8vo. Lond. 1831,
where there are copious references) ; Boehmer ae
4to et Sto ramo ex arcu aorte prod. in Haller.
Disp. Anat. Collect. t. ii.) ; Petsche (Sylloge Obs.
Anat. Halew, 1736); Penada (Saggio di Osserv.
pathol. anatomiche, Padova, 1801); Burns (Obs.
on the diseases of the heart, 8vo. Edinb. 1809) ;
Nicolai (De directione vasorum); Biumi (Obs.
anatomice) ; Bertin (Maladies du ceur, 8vo. Paris,
1824); Bernhard (Diss. de arter. e corde pro-
deunt. aberrationibus, 4to. Berol. 1818); in the
various systems of anatomy, particnlarly those by
Heister, Winslow, and Hildebrandt, by Weber.
in Morgagni, (Epist. &c. De Sinubus arteria magne
Com. Bonon. t. i.) Hunauld, (Obs. Anat. sur une
conformation singul. de l’aorte, Mem. de Paris,
1735); Fiorati, (Osserv. sopra un insolita positione
dell’aorta, e stravagante origine de suoi primi rain},
in Saggi de Padova, t. i.); Murray, (Sonderbane
Stellung einiger grosseren Pulsader-stamme, Ab»
hand. der Schwed. Akad. Jahr 1768), Vicg d’Azyr,

198 ARACHNIDA.

(Manque de l’anastomose qui reunit les deux arteres
mesenteriques, Mem. de Paris, 1776), Du Verney,
fSay les vaissaux omphalo-mesenteriques, Mem. de

aris, 1700) ; Chaussier, Se les vaissaux ompha-
lo-mesenteriques ; Nouv. Mem. de Dijon, A. 1782.
Societ. Philomath. anl1); and Tyson,( Unusual con-
formation of the emulgents, Philos. Trans. 1678.)

(J. Hart.)

ARACHNIDA; agayyn, aranea; Eng.
arachnidans ; Fr. arachnides ; Germ. Spinne ;
Ital. Ragni.

This class of animals was for a long time
confounded with that of insects, but it has been
distinguished therefrom by many modern natu-
ralists, and more especially by Lamarck, who
has applied to it the term ‘ arachnides,’ now
universally adopted.

The characters indeed which the arachnidaris
present are perfectly distinct, and prevent them
from being confounded either with crustaceans
or insects, although one cannot avoid perceiving
that they have numerous relations with the
animals of these two classes, and they are con-
sequently placed in natural arrangements be-
tween the crustaceans and insects.

Zoologists have assigned the following cha-
seg as peculiar to and distinguishing this
class.

Body divided into thorax and abdomen;
apterous. Legs, eight in the adult state. Head
continuous with the chest. Eyes smooth. Sezr-

Class.
ARACHNIDA.

ual orifices situated either on the thorax or base

of the abdomen.

To these external characters may be added
others derived from the anatomical conditions
of different organs. Thus all arachnidans pos-
sess exclusively an aerial respiration, either
effected by a sort of lungs, or by means of
tracheal tubes, as in insects. This difference
in the respiratory organs is accompanied with
one not less marked in those of circulation ;
for example, all the pulmonary arachnidans
possess vessels which carry blood, while, on
the contrary, all those which have trachee are
deprived of bloodvessels. Lastly, the latter
species (or trachearies) alone undergo metamor-
phoses analogous, in some respects, to those of
insects; while the former (or pulmonaries)
suffer only changes of integument. We shall
treat further on these peculiarities hereafter.

Our object here not being to treat of classifi-
cation, we shall refer the reader for this subject
to the works of Cuvier, Leach, Latreille,
Walcknaer, Dugés, and limit ourselves at pre-
sent to a tabular exposition of the principal
divisions and subdivisions admitted in this
class down to the genera with which it is most
essential to be acquainted.

Latreille, whose method is that most gene-
rally adopted by zoologists of every country,
divides the arachnidans into two great orders,
as follows :—

Orders.

Pulmonary sacs for respiration, 6 to 12 ocelli. .....+s+e04 PULMONABIA.
Trachee for respiration, not more than 4 ocelli. ........+. TRACHEARIA.

The same author establishes in the first order two families, which are characterized as follows :

1st Order. a moveable and perforated

poisonous liquid ....+...

( Palpi simple, pediform; mandibule armed with

Families.

eeeeeee@ ARANEIDZ:

claw, emitting a

ARACHNIDA Abdomen inarticulate, terminated by spinnarets
y sp

PuULMONARIA.

M. Walcknaer, who has made a special
study of the family of araneide or spinning
arachnida, and who has published many works
on their methodical distribution and their habits

Palpi produced, cheliform, or shaped like pin-

cers eet@eeeeeeeee eeee? Ge
Mandibule provided with a moveable digit ..
| Abdomen articulate, without spinnarets ......

ctessoccd LDIF ALES

of life, has very recently considered them with
the express view of arriving at a natural arrange-
ment of them; the result of his labour may be
seen in the following

a )

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200

ARACHNIDA.

Of the external covering or tegumentary
system.—Although the external covering of the
arachnidans varies in consistence, according to
the part of the body which is examined,
yet it may be said in general to be more or
less soft, rarely acquiring the solidity of the
integument of certain insects, and still less
the hardness of that of many crustaceans.*
Where it is of the greatest consistency it is
elastic, of a deep brown colour, and has an
aspect analogous to horn. In chemical com-
position, however, it is always widely different,
as has been proved by the researches of M.
August Odier, and some other chemists. It
contains, in fact, a substance sui generis,
called ‘ chitine,’ which is insoluble in potassa,
but, on the contrary, is soluble in warm sul-
phuric acid, does not turn yellow with nitric
acid, and does not curl up when burnt, but
leaves an ash, which, if the part experimented
on is sufficiently thick, preserves the form of
the organ.

The solidity of the outer covering is gene-
rally greater on the thorax than on the abdo-
men. The genera scorpio, phrynus, theli-
phonus, and phalangium, afford an exception
to this rule, the rings of the abdomen being
distinct and solid, especially on the dorsal

ect.

In the spiders properly so called, (aranea, )
and in the greater number of the mites (acari ),
the skin of the abdomen is very soft, coria-
ceous, papiraceous, or even membranous,
transparent, and susceptible sometimes of be-
ing greatly extended. It is on this account
that the abdominal segment of the body shrinks
and loses its form after death, and from the
transparency of the integuments the same
arachnidans present during lifetime the various
markings and lively colours which depend on
a kind of pigment situated in the interior of
the body.

The head, as we have remarked in our ex-
position of the characters of the class, is always
consolidated with the thorax; this is readily
ascertained to be the fact in scorpions and
Spiders, and in order. to express this dispo-
sition, which obtains also in many of the
crustacea, the two united segments are termed
* cephalo-thorax ;’ the term abdomen is applied
to the part properly so called, and thus the
body of the arachnidans may be divided into
two The abdomen may be either sessile
or pediculate, i.e. it may either inclose at its
anterior margin the posterior part of the thorax,
as in the scorpions, or it may adhere to the
thorax by a very circumscribed part of that
Margin, as in the spiders properly so called.
Anatomically speaking, the abdomen has a
very simple structure: it is formed of annular
segments sometimes distinct and hard, as in
the scorpions; sometimes blended together
and soft, as in the spiders and mites.

The other division of the body or cephalo-
thorax is not so simple. To facilitate the study

* This composition being precisely analogous to
that of the integuments of insects, we shall treat
of it in the article relating to these animals.

201

of this part it.is necessary to consider the
cephalic portion separately from the thoracic
division. This it is easy to do, where, as in
many cases, the junction of the two parts is
perfectly distinct, and made obvious by the ex-
istence of a furrow along all the whole superior
part of the line of union, (see the traces of it
in the thorax of a pholque, pholcus rivulatus,
Jig.79.) But in every case the head (a) is recog-
Fig. 79. nizable by constant
a characters: it supports
the eyes and all the
pieces belonging to
the oral apparatus,
while the thorax (6),
on the contrary, gives
insertion to the four
pairs of legs, which
on account of their ex-
treme length are repre-
Ly sented in the figure as
Pholcus rivulatus. truncated.

The head is often as narrow as the chest,
abruptly truncated anteriorly, and terminated
by a point posteriorly, so that it appears by its
backward prolongation to separate the right
from the left side of the thorax, and to be
placed between them like a wedge, (as in
the pholcus.) The suture is very close, and
sometimes so far effaced that it is no longer
possible to decide where the head ter-
minates and the chest commences. We
have already observed that the head sup-
ports the eyes on its upper part, and has the
oral instruments attached to its lower surface.
These consist, first, of a pair of mandibles or
forciples; secondly, of a pair of mazille ;
thirdly, of a sternal labium.

The number of annuli or segments which
enter into the composition of the head of an
arachnidan may yet be determined at some
future period: we have made some attempts
to unravel this subject, but our observations
are not yet sufficiently matured to permit us
to decide so difficult a question.

Our researches on the thorax of articulate
animals have led to more decisive results,
which we shall now expound, but for the
complete understanding of which we must
refer the reader to the article Insgcra,
where a more general theory of the thorax,
and a description of all the pieces that enter
into its composition will be given. In the
arachnidans many of these pieces are entirely
wanting; and their thorax is consequently
more simple than that of insects: it is even
more simple than the thorax of crustaceans,
to which, however, it bears a great resemblance
in many points. If, for example, we take a
large spider, as a mygale avicularia, and stri
off the hairs which clothe the thorax, we shall
easily perceive a plate, or plastron, interme-
diate to the right and left series of legs. This
plastron is the sternum, or, to speak more cor-
rectly, the union of several sternums, which,
were it not for this union, would manifest
themselves as four distinct pieces; that is to
say, corresponding in number to the pairs of
legs which arise from them. This sternal plas-

202

tron is distinctly shewn in fig. 100, e, which
represents the inferior surface of the body of
the house-spider, (¢egenaria domestica.)

On the upper surface of the chest we find
another plate much more extended than the
sternum, and joined anteriorly with the head
by means of a fissure or triangular V-shaped
notch which receives it. This plate or dorsal
shield exhibits divisions or rather lines of
suture which the eye readily distinguishes.
They represent arcs of circles arising from the
base of the legs and all ending in the centre
of the thorax, where there is a depression
varying as to extent and depth according to
the individual. In other arachnidans this
structure is not so clearly shewn on account
of the close union of the different pieces; but
it is easy to detect or at least explain the un-
important modifications which obtain in these
cases. In the tigure, which we have taken
from Savigny, of the pholcus rivulatus, the
traces of the division may be readily followed,
(fig. 79, b.) Continued comparative researches
have convinced me that this dorsal plate of the
thorax of the araneide is formed, not of the
dorsal pieces of the thorax of insects, but only
of the lateral pieces. or those of the flancs.
For the arachnidans being deprived of wings,
the intermediate thoracic element or tergum,
so largely developed on account of the pre-
sence of those organs in the thorax of insects,
being no longer necessary, has completely dis-
appeared. How has this taken place? The
flancs (pleure.) which in insects were diva-
ricated and pushed to the sides by the tergum,
when that obstacle was removed, have mutu-
ally approximated and become united toge-
ther in the middle line, precisely at the place
where the little depression exists which we
have already mentioned.

We believe that we have placed these facts
beyond all doubt in our ‘ Researches on the
Thorax of Articulate Animals,’ presented to
the Academy of Sciences of Paris in 1820.*
Now it is worthy of remark that what has hap-
pened to the arachnidans, being animals de-
prived of wings, is also found in the crusta-
ceans, which are equally destitute of these
organs. Only that there exists in some of the
latter, as the decapods, a vast carapace which
occurs independently of the flancs, and covers
them. For if the carapace is raised in a crab,
the flancs or pleurz are seen beneath, extending
obliquely towards one another as in the thorax
of a mygale, with this single difference, that
in the cancer, where the carapace covers the
flanes and protects them as well as the internal
soft parts, the pleure or side pieces remain
divaricated and are not joined at their apices
as in the mygale.t+

* See the Report by Cuvier, in the Analysis of
the Works of the Roya] Academy of Sciences for
the year 1820.

+ We must again refer to the articles CRUSTACEA
and INsecTA for the full comprehension of the facts
which presuppose an anatomical knowledge of the
external covering of the animals of these two
classes. To those who already possess that infor-
mation } shall observe that a single piece of the

ARACHNIDA.

Digestive system.—The arachnidans, whose
habits have been made the subject of obser-
vation, feed for the most part on animal matter,
not in a state of decomposition or even re-
cently dead, but in the living state. They
either boldly seize their prey, which consists
of insects of greater or less size, or they
attach themselves to animals much larger
than themselves, and live parasitically upon
their blood or some other nutritious fluid.
The latter species are generally very minute :
many of them, as the mites (acari), require
our best optical instruments for their detection.
The above differences in habits of life are
accompanied with important modifications in
the organs of nutrition, and especially in the
oral apparatus, which we proceed to de-
scribe.

In the non-parasitic species, as the pulmo-
nary and part of the tracheary arachnidans,
the mouth consists essentially, first, of two
mandibule or forciples (fig. 80, a) in close ap-

Fig. 80.

position, endowed with little lateral motion,
but rather acting vertically and provided each
with a hooked claw (6), which, near its point,
is perforated, and emits a poisonous fluid,
secreted by a gland, hereafter to be described.
In other arachnidans of the same order the
mandibul@ are a species of pincers, one nipper
of which is alone moveable, as in the scor-
pions. Secondly, of two maville (cc), each
in the form of a more or less flattened and
villous lobe, provided with a palp or jointed
appendage (d) projecting more or less from the
mouth, and terminated sometimes by pincers
as in the scorpions, sometimes by a simple

filancs of insects (epimera) forms the back-part of

the thorax of spiders; the other piece (episternum) _

already in a rudimentary state in the ciustaceans,
has completely disappeared from the thorax of the
arachnidans, each segment of which consequently
consists only of two pieces, the sternum below, the
epimera above. :

ARACHNIDA. 203

claw, as in the spiders, at least the females,
for in the males this palp is frequently the seat
of a singular apparatus (e), hereafter to be
described. Thirdly, of a sternal labium (f),
which, as its name implies, is inserted into the
sternum, and dves not give origin to any arti-
culated appendage or palp. With respect to
the composition of the mouth in the parasitic
species, such as most of the mites, and we
may take as an example an argas, although
it is concealed under the form of a beak,
sometimes with a sharp
point, yet it is essentially
the same. The principal
difference consists in the
dart-shaped mandibles
(a a), being joined toge-
ther so as to form a kind
of lancet, the sides of
which are sometimes
denticulated, so as to
cause them to adhere
firmly to the flesh which
they have penetrated.
The maville with their

‘ palp (6) and the inferior
Head of a mite( Argas-) (abium (c) are here more

or less intimately blended together, so as to
form a case or sheath. In some instances the
maxillary palp remains free, as in the argas.
Savigny admits that in the interior of the
mouth of arachnidans there exist three pharyn-
geal orifices, and not a single one as in crus-
taceans and insects. These three orifices,
which are of almost imperceptible minuteness,
are situated at some distance from one another,
and disposed in a triangular form. He has
observed this structure in spiders, scorpions,
and phalangians: but he represents only two

Fig. 81.

orifices in a genus allied to galeodes. Latreille

denies the fact, and Treviranus, in his anato-
mical description of arachnidans, mentions
only one pharyngeal orifice.

However this may be, Savigny confines the
assumption of food in spiders to a true suction :
“« The mandibles,” says he, “ do not serve for
bruising the food, but for seizing it, and for
piercing and retaining it in firm contact with
the maxille ; these subject it to alternate pres-
sure, and express the juices which afterwards
pass into the pharynx.”* This is a matter
of daily observation when a spider seizes an
insect.

The intestinal canal of the arachnidans is
always short, and is never disposed in convo-

lutions as in certain herbivorous insects. This
disposition is in accordance with their preda-

ceous habits, and confirms the general rule,
(but which to our knowledge is not without

_ Many exceptions,) that the intestinal canal is

longer in herbivorous than carnivorous animals.
_ In the spiders, (aranee,) and we may take
the common species (tegenaria domestica) as

* See Description of Egypt, Arachnidans, pl. 8,
7, E, y y- Savigny at first admitted but two
geal openings, (Mémoir sur les Animaux

sans Vertebres, p. 57); but subsequently admitted

Tegenaria domestica.

an example, the alimentary canal (fig. 82.) com-
municates with the mouth between the maxille
(a a) by an cesophagus, rather short and of a de-
licate texture (b). This terminates in four sacs
(c), which M. Treviranus calls “ stomach,” but
which, in our opinion, merit rather the name of
gizzards; the digestive tube then continues,
as a straight narrow canal (d) of moderate
length, which dilates (e) and adheres, by its
parietes, to a kind of epiploon filled with adi-

ose granules (f). Posteriorly the dilated part
fctnes stronger in texture, insensibly con-
tracts(g), then undergoes a second dilatation (A)
before it opens into the rectum (7). It is near
the latter part, in a kind of pouch, that the
slender vessels open which M. Treviranus calls
biliary vessels, and which he is, with reason,
surprised to see terminating in so extraordinary
a position. These vessels, in fact, which cha-
racterize so well by their presence the chilific
stomach of insects, and are situated in these
animals more or less anteriorly, always pre-
ceding the small intestines which have a greater
or less length, terminate in the spiders in the
rectum itself, and close to the anus.

204

Now if the observations of M. Treviranus
are correct, and the four vessels which he de-
scribes are really analogous to the biliary tubes
of insects, we do not hesitate to. consider all
the part which precedes and is intermediate to
them and the four sacs, as the stomach, or
chilific cavity. It would thus result, that the
tegenaria domestica would be deprived of an
intestine ang so called, and would pos-
sess no part destined to transmit along a greater
or less extent the residua of the digestive pro-
cess. And, indeed, such residua must neces-
sarily be very inconsiderable in an animal
which is sustained by juices, and these already
animalized. We are, indeed, led to this con-
clusion by the structure presented by the he-
mipterous insects which are nourished, like the
spiders, by suction, and which also have’ the
intestines, properly so called, so short that the
biliary vessels, which always accompany the
posterior extremity of the stomach, are found
close to the anus. We may form an idea of
this disposition by casting an eye over the
beautiful figures which our friend M. Leon Du-
four has just published in his “ Anatomical and
Physiological Researches on the Hemiptera.”

In the alimen-
bs, tary canal of the
eg scorpions _ the
biliary vessels
dd are inserted
; much higher up,
‘ but this is not
| athe only pecu-

liarity = which
the anatomy of
these animals
presents. Their
digestive tube
extends without

any marked di-

latation straight
from the mouth

(a) to the anus

which opens at

the extremity of
Sejy” © the tail. It pre-
sents in this
course a very
singular struc-
ture: five small
canals (b) go off
at right angles
from either side,
above the place
of communica-
tion of the bili-
ary vessels, and
terminate by
ramifying in
the fatty masses
which make a
sort of epiploon
(c.) This tru-
ly remarkable
structure is not,
however, so an-
omalous as
might be sup-
pase eimeully

ARACHNIDA.

ae

if we regard as ccecums these kind of lateral ves-
sels. For the alimentary canal presents a still
more ramified condition in some crustaceans,—
we would cite as an example the argulus studied
by Jurine;* and in another animal of the same
class which M. Milne Edwards and myself+
have made known under the name of Nicothoe,
the intestinal canal sends out considerable
lateral prolongations. In the leech, and es-
pecially the Clepsina, there exist numerous
cecums. Lastly, certain minute arachnidans
(acaride) are remarkable for analogous lateral
dilatations. It is to be observed that all these
beings are sustained by animal juices, and the
great part, for the better gorging of the same, are
fixed either momentarily or during their whole
life upon the body of their victim.

We now come to speak of the epiploon and
the fatty globules which it contains. The fat,
or the substance which appears as such, is ex-
tremely abundant in the bodies of insects and
arachnidans. In the latter it assumes the form
of granular masses or globules of various co-
lours, and sometimes these are united together
by a thin membrane. In the aranez the fat is
especially abundant in the abdomen, of which,
indeed, it determines the form. The use of
this fatty apparatus cannot be mistaken, and it
has been placed beyond doubt by experiment,
that it supplies the place of nourishment to the
animal, either when the latter passes the winter
in a state of torpidity, like the hibernating ani-
mals, or when in particular seasons circum-
stances are not favourable for catching prey.

Respiratory system.—The division which has
been established in the class Arachnida of Pul-
monaries and T'rachearies indicates that there __
are in these animals two very different modes |
of respiration. In both cases the atmosphere
penetrates to the interior of the body by orifices
situated on different points of the body, and ;

:
cL

———.

EE Ss

called stigmata. The stigmata of the Pulmo-
nary Arachnidans, and especially those of scor-
pions, are very conspicuous; they occupy the
inferior part of the abdomen, and are four in
number on either side, (1, 2, 3, 4, fig. 84.)
They are in the form of narrow fissures, sur-
rounded as in insects with a circle of more
solid substance than the rest of the integument,
and to which we have given the name of pe-
ritrema.

In the spiders (aranee) not only do they
differ in form but in number and _ position.
Treviranus counts four pairs in the thorax
above the insertion of the legs, four pairs on
the upper part of the abdomen, and one pair
on the lower surface; the latter is the most
constant and important, (fig. 100, d.)

The stigmata of the T'racheary Arachnidans —
are less easy to be distinguished, more espe-
cially on account of the small size of the
species constituting a part of that group.
We have here carefully figured them in an
Acaroid species ( I’vodes Erinacei ), where they
are situated below the sides and on we er
part of the abdomen, (fig.85, a,) in shape like
a spherical tubercle, fie 86, a,) perforated by

* Annales du Muséum, tom. viii. p. 431. 4
+ Annales de. Sciences Naturelles, first serie
tom. ix. pl, 49,

alll

ARACHNIDA. 205

Fig. 84,
.
~ \/ Py. ;
: ogee ;
\ se || VE
AGU
be ts

ay i te

an infinite num-
ber of small
holes, between
which in the
centre we may
remark a larger
circular _ plate
(b.) Each little
aperture is as it
were stellated at
. the margins (c,)
/ sah by which the
; air penetrates

SSES8 the body and
"Se gets into the
; i, trachee. These

: RA "a
fon RO} 3 trachez are ana-
a AN ee logous in struc-

DN See ture and posi-
WSS tion to those of
insects ;they are

5 | :
a ay elastic, ramify

after the man-

___ her of vessels in the interior of the body, and

penetrate to even the minutest organs.
With regard to the internal respiratory organs
of the Pulmonary Arachnidans they have a
very different character; presenting the ap-
pearance of membranous sacs formed by la-
mellz applied to one another like the leaves of
a book, each of these little receptacles opens
a common cavity, the hiebeacus mar-

gins of which adhere to the horny circle or
peritrema of the stigma before described.

We here subjoin figures copied from those

of Professor Miiller of Berlin, which represent
these parts in a scorpion. Fig. 87 shows one of

Fig. 87.

Fig. 88.

C.au

the pulmonary branchiz entire, seen in profile:
a is the edge by which it adheres to the circum-
ference of the stigma; b the simple membrane
without folds; c the folds or leaves. Fig. 88
shows a portion of the same pulmonary branchia

' laid open: a is the horny margin of the stigma,

or peritrema, to which the simple membrane 6
adheres ; c the common cavity into which each
of the spaces opens which are formed by the
lamine.

These organs resemble closely in their struc-
ture the branchial lamine, and hence Trevi-
ranus and Meckel compare them to branchie.
Miiller on the other hand maintains that they
are lungs, because, he says, they can be dis-
tended with air. The name of pulmonary
branchiz, which we have given them, seems to
reconcile the two contending opinions, although
we believe that the distinction between lungs
and gills is in itself of very slight importance
when applied to articulate animals. It is, for
example, quite impossible to establish such a
distinction in certain crustaceans, as the Onis-
cus, the Asellus, the Cymothoa, which are all
provided with organs of an analogous structure,
although some live in water, and others in air
more or less humid. Moreover, certain crabs,
as the terrestrial species called Cancer Uca,
Ruricola, &c., of Linnzus, possess branchie
which are much better adapted for respiration
in air than in water. The Cancer Menas, so
common on our coasts, is almost in the same
case, since it passes a great part of its life out
of the sea, and it is well known that lobsters
and shrimps can live a long time out of water,
provided that the air in which they are kept is
humid. M. Milne Edwards and myself have
demonstrated, by decisive experiments, the
conditions in which the branchie in these
animals act as lungs.

Circulating system.—-The function of cir-
culation, which is always so intimately con-
nected with that of respiration, presents, as
might be supposed, two different conditions
in the arachnidans. Those which breathe by
means of trachee have not an apparent circu-
lation; and in this respect they resemble in-
sects :—we attribute to them simply a dorsal
vessel without any ramifications. Those, on
the contrary, which possess branchial lungs,

206

have an apparatus for circulation pretty well
developed. It consists of an elongated vessel
placed immediately beneath the integument
along the middle line of the dorsal aspect of
the back, on which account it has received the
name of dorsal vessel (fe: 89). It is kept in
its situation by small ligaments or muscles,
(a a), which in insects are called ale cordis.
The texture of the dorsal vessel is membranous,
and pretty firm; it contains a colourless fluid.
This heart is in communication with numerous
vessels, but hitherto it has not been discovered
which of these terminate in, or which arise from
the organ, or, in other words, it is not known
by what route the blood arrives at, or proceeds
from the heart. We believe that we are able
to dissipate the doubts which still exist as to
this subject, but before we state our opinions
we shall speak of the anatomical disposition of
the apparatus. Treviranus has described it
vaguely in the scorpions, but has well elucidated
its structure in the spiders (arane@ ), more par-
ticularly in Clubione atrox and Tegenaria do-
mestica, Fig.89. In both these species nu-
b merous vessels are
pra observed to arise
| Wie------------- r from the heart, es-
AE pecially from its
| = nigel part (cc.)
hese proceed to
e---------- @ Yamify indefinitely,
distributing them-
- e Selves over every
aie a organ; and we
,bave no doubt
e With respect to
ho... g their true arterial
“= nature. But in ad-
‘Nii @ dition to these ves-
| sels there exist two
iew~z-- a others of larger
RSS". , size (d d,) which
= communicate in
= —s- “ one: direction with
Ste AER athe heart, in an-
Wy... g other, by very fine
; ramifications, with
WS the ulmonar
vs begin In Chi-
bione atrox these
b two vessels do not
Tegenaria domestica. give out any
branches in their course. No doubt remains
in our mind but that these vessels maintain a
direct communication between the heart and
respiratory organs. The subjoined figure
(fig. 89) will facilitate the understanding of
these facts. It represents the heart and its
appendages in the house-spider, ( Tegenaria
domestica,) and shows the two canals which
communicate with the heart and receive the
stall vessels (ee ee) that come from the pul-
monary branchie. Treviranus, to whom we
owe these observations, has not, however, at-
tempted to explain the manner in which the
circulation takes place in the arachnidans, and
indeed this is to be determined by physiolo-
gical experiment and not by the dissection of
the organs merely. The experiments which I

ARACHNIDA.

have made, in conjunction with my friend M.
Milne Edwards, on the circulation of the crus-
taceans, enable me to give a satisfactory and
doubtless true explanation of that of the arachni-
dans. The organs which exist in these animals,
and we admit the precision of the anatomical facts
detailed by Treviranus, are essentially the same
as in the crustaceans. We find a heart, of the
nature of which no one can entertain a doubt :
then there are arteries proceeding from the
heart and ramifying over every part of the
body; lastly, the heart receives on each side
vessels which bring it into communication with
the respiratory organs. These latter vessels are
the analogues of the branchio-cardiac vessels
of crustaceans. With respect to veins, of which
the latter animals are destitute, they are equally
wanting in the arachnidans, and are doubtless
replaced by cavities of an irregular form which
exist between all the organs of the body. . Tre-
viranus, indeed, has remarked in the abdomen
of Tegenaria domestica two small intervals
which are discoverable through the integument,
and in which he says the blood may be ob-
served to be collected. These reservoirs are
perhaps the analogues of the venous sinuses of
the Crustacea.

The nature of the vessels being thus deter-
mined, it becomes easy to conceive how the
circulation takes place in the arachnidans—
the blood, leaving the heart, is distributed
through all the arteries to the different organs
for their nutrition: this being effected, and the
nutrient fluid being thereby converted into ve-
nous blood, it begins to circulate through the
sinuses before mentioned, and arrives by an
insensible course at the pulmonary branchie.
There it is changed by contact with air into
arterial blood, and returns to the heart by
means of the branchio-cardiac vessels (ed) to be
finally again propelled through the arteries (c.)

Thus the ascertained anatomical facts, few
as they are, permit us already to appreciate the
mode of circulation in the arachnidans; and we
repeat that it is in every respect analogous to
the circulation in the crustaceans.

Nervous system.—The nervous system is
gangliated, as in all the articulate animals;
but it presents considerable differences of dis-
position in the different arachnidans: the
scorpions in this respect vary much from the
spiders.

In the Scorpionide we find the following
structure (fig. 90):—the first ganglion, which
is commonly called the brain (a), and which
supplies the nerves to the parts of the mouth (6,c)
is intimately blended with the nervous mass
giving origin to the nerves of the legs (d). The
succeeding ganglia are distinct from one an-

other, and are seven in number: the first three
(1 2 3) are situated in the abdomen proper; —

they have this peculiarity, that they are united —
together and with the ganglion, which may be ~
termed cerebro-thoracic, by three instead of ©
two chords of communication (e), which is the —

number found in all other articulate animals; _
the four remaining ganglions (4 5 6 7) occupy —
the entire length of the post-abdomen, or that —
contracted portion of the body which is incor- —

‘
es

is
7
:

_ the body in which they are seated.

ere A

ARACHNIDA. 207

rectly termed the

tail.
In the Aran-
' “ide the ganglions
are fewer than in
the Scorpionide :
\\ dthe first pair, or
that which consti-
\lc a tutes the brain,
(fig. 91, a,) is quite
distinct from the
. thoracic ; these are
yyy Jour innumber (6d)
but have — under-
gone a remarkable
|. g degree of centrali-
Lai zation, being inti-
f \\ mately connected
I \ together so as in-
| deed to form a
\ mass in which all
traces of junction

eta :

we enw = EEE

are lost, except at

Ber Soe. 3 the sides, which
/ have remained free
and in the form of
smallconoid bodies
directed outwardly
so as to resemble,
in the aggregate,
the figure of a star.
From the apex of
each of these small
cones the nerve is
given off to each
leg. In the abdo-
5 men there does not
exist any ganglion,
but only a double
longitudinal ner-
vous cord(c),which
£8 swells out at its ter-
mination. From
this swelling (d) a

nerves (ee) pass off,
which x0 ious
buted to all the
organs contained
in the abdominal
cavity.

Organs of sense.
—We have no-
thing particular to
observe with re-
s to the smell or hearing of the arachnidans,

r we are ignorant of the existence of these
senses in the class, or at least of the parts of
ith re-
gard to taste, the choice which the arachnidans
make of their food sufficiently indicates that it
exists in variable degree; the organ is situated

bly at the entrance of the pharynx.
ith regard to touch, the delicacy of that sense
is in the ratio of the tenuity of the integument;

_ but the extremities of the legs, and more
especially of the maxillary palps seem to

be expressly destined to bring the individual

great number of -

into relation with sur-
rounding objects. The
sense of sight is the
only one respecting
which no doubt can
exist; particularly in
the species which are
the most perfect of the
class, such as the spi-
ders, scorpions, &c.
--c The eyes belong to
that kind which are
termed simple, in op-
position to those de-
nominated compound,
and which are found
exclusively in insects
and crustaceans.

These simple eyes
(ocelli ) in arachnidans
are two, four, sia, or
eight in number ; they
are situated on the an-
terior part of the body
either superiorly or la-
terally. With respect
to size they differ not
only in different spe-
cies, but in the same
individual, as in the
Platyscelum, (fig. 92,) and especially in the
Attus.

In the Scorpions (fig. 93) there are two
eyes (a «) situated on the dorsal aspect of the

Fig. 93.

cephalo-thorax, and closely approximated to
the mesial line: these are of much larger size
than the minute simple eyes (6 6), which are
placed on the sides and near the outer margins
of the same segment. The two mesial eyes,
on account of their size, have been selected by
Miiller for the subject of his researches, which
he published at Leipsic, and which have been
translated by extract in the 17th volume of the
first series of the “ Annales des Sciences Natu-
relles.”. The following are the principal re-

208 ARACHNIDA.

sults of the labours of this accomplished na-
turalist.

He finds that each of these simple eyes is
composed, ist, of a cornea; 2dly, of a crys-
talline lens; 3dly, of a vitreous body; Athly,
of a kind of chamber; 5thly, of a choroid;
6thly, of a retina.

The cornea, as is shewn in fig. 94, which
represents a vertical section of the eye, is
smooth and con-
vex externally (a,)
its superficies pre-
ssennanscosen- a senting none of
those divisions
which characte-
rize the cornea of
t. the compound
‘we eyes of insects.
The internal sur-
face is deeply
concave, and in
the hollow he-
misphere thus
formed is lodged the anterior part of the crys-
talline lens. This body (b) is of a spherical
figure, of a hard and transparent texture, resem-
bling in these respects the crystalline lens of
Fishes. Posteriorly it rests upon but does not
penetrate the vitreous humour. The vitreous
humour (c) is composed of a granular, soft
material, is larger than the chrystalline, plano-
convex anteriorly, wholly convex behind. As
the crystalline lens rests upon without sinking
into the vitreous humour, there remains a cir-
cular channel or space filled with an aqueous
humour, to which the term chamber may be
appropriately given, and which may be com-
pared to the posterior chamber of the eye of
some of the vertebrata.

The retina (e) is applied to the back part of
the vitreous humour, and is in some degree an
expansion of the optic nerve (g). It is lined by
a choroid, or membrane saturated with a co-
loured matter, or kind of pigmentum (f'), which
is afterwards reflected over the anterior margin
of the plano-convex surface of the vitreous
humour so as to form there a sort of pupil, the
aperture of which exceeds the diameter of the
crystalline, but is less than that of the vitreous
humour. Such is the somewhat complicated
structure of one of the large eyes of a scorpion,
by the knowledge of which physiologists are
now enabled better to understand the mode in
which vision is effected in the arachnidans.

Organs of secretion.—We designate thus the
organs that emit outwardly a matter which is
sometimes liquid, and sometimes becomes con-
crete by contact with the atmosphere. The
position of these organs varies; in one case
they occupy the anterior part of the body, in
another they are observed at the opposite extre-
mity. The nature and properties of the matter
secreted is not less variable ; in some instances
it is an irritating or poisonous liquid which the
animal introduces by means of a more or less
sharp pointed hook into the interior of the body
to which it may be applied; in other instances,
again, it is a substance which is at first in
a liquid state, but soon becomes solid in its

Fig. 94.

passage through a sort of sieve, or, if I may be
permitted the comparison, a cullender pierced
with excessively minute holes. We shall treat
separately of these two kinds of apparatus.

Of the apparatus for secreting the irritating
or poisonous liquid.—Every
quickly a fly that has been bitten by a spider
expires: the effect is instantaneous. It is by
means of the mandibule or forciples that the
spider has inflicted the wound. These mandi-
bule are each armed with a moveable and ex
tremely sharp claw, (fig. 95, a,) near to the

point of which is a minute orifice (b), from

which there escapes a dro
of poisonous liquid, whic

Fig 95.
- ~.) spreads itself over the whole

inflicted. This orifice, which
from its minuteness is very
E ...-¢ Aifficult to be perceived even
with a high magnifying pow-
er, communicates with a fine
or narrow excretory canal (c),
Mj, situated in the interior of the
)\-—----- ad mandible and given off from
Yy the true secreting organ. This
gland is lodged in the inter-
space of the muscles of the
thorax; it is in the form of
an elongated and _ slightly
curved vesicle, the parietes
of which have a_ singular
structure. Treviranus describes it as consisting
of filaments adhering together and united by a
membrane so as to resemble a spirally disposed
band. This structure presents, he thinks, some
analogy to that of the trachea of insects. Ly-
onnet, in his posthumous work, has described
this part somewhat differently: he considers
each little band as being composed of two sub-
stances, one fleshy, which contracts upon drying,
the other squamous, which is disposed likea
watch-spring, or rather like Archimedes’ screw,
and which always remains in the same state.
He supposes that these fibres, upon contracting,
force the poisonous liquid into the excretory
canal. Such a construction is not, however,
necessary, since it may be readily conceived
that that vesicle, being placed in the midst of
very powerful muscles, it is sufficient that they
contract in order to its compression and the
consequent propulsion of the fluid contained
in its interior, which probably the parietes have
secreted.

This apparatus appears to us to correspond,
by its position, to that which is termed, in in-
sects, the salivary apparatus, and in silk-worms
the silk-glands: it is even possible that the
poisonous fluid itself, mingling with the ani-
mal juices which the spider introduces
suction into its stomach, serves to facilitate
digestion.

Spiders are not the only animals of their —
class that are provided with this kind of organs.
Scorpions have also a poison-apparatus, but in —
It is not placed in

a very different position.
the mandibles, but at the posterior part of the

body, in the last segment of the tail-like abdo- _

men. Every one is familiar with that pyriform

one knows how

wound the instant that it is

.
kc

dilatation which the scorpions carry at the end
of the tail; it is terminated by a little sharp
hook generally curved backwards. Near its
termination there may be observed, as in the
mandibulous hook of spiders, a very minute
orifice, or, according to some authors, two dis-
tinct fissures. It is from this part that a lim-
pid fluid, having strongly-marked poisonous
qualities, exudes; and, corresponding to the fo-
ramen within, there is the neck of a little blad-
_ der which is the true secretory organ. Little is
known respecting its structure: according to
the observations of Treviranus it is surrounded
by a horny substance and provided with a
muscle, which most probably has for its func-
tion the compression of the vesicle. and the
consequent expulsion of the poison.
Apparatus for secreting the fluid which con-
cretes in the air—This apparatus is peculiar to
certain arachnidans: it does not exist in the
___- Scorpions nor in many other genera; but when
present it is always situated at the posterior
part of the body. The threads by which the
__ spiders suspend themselves, and of which they
_ Spin their webs, are emitted from the extre-
mity of the abdomen. There we find, in -the
vicinity of the anal aperture, several small
appendages, which it is important not to con-
_ found with one another, (fig. 96.) Of these
__ there are two which are small articulated hairy
Fig. 96. and filiform processes
(6 6;)* the others are
spinnarets, or the or-
gans by which the
:..¢ silky threads are emit-
ted. Of the latter,
~ @ four may generally be
, counted, (cd.) Their
structure 1s very re-
markable; it has been
. @ described by many
_ anatomists, and among others by Lyonnet in
his posthumous Memoirs. This patient anato-
mist has discovered that the surface of each of
| the spinnarets is pierced by an infinite number
| of minute holes, from each of which there
escapes as many little drops of a liquid, which,
_ becoming dry the moment it is in contact with
the air, forms so many delicate threads. Im-
mediately after the filaments have passed out
of the pores of the spinnaret, they unite first
_ together, and then with those of the neighbouring
_ Spmnnarets to form a common thread ; so that the
_ thread of the spider, as it is empioyed in the
_ manufacture of the web, or such as the creature
_ Suspends itself by when hanging from one’s
,° - * Mr. Blackwall, who has published some inter-
estin ations on the structure and functions
of ers in the third report of the British Asso-
Te ae 1833), and more at length ina recent volume
§ 0 the Li Transactions, considers these pro-
__ eesses to be also spinnarets. They are provided
_ with tubes, which, arranged along the under side of
_ the terminal joint, present the appearance of fine
_ hairs projecting from it at right angles; if examined,
when in operation, by a poweriul magnifier, the
function of these tubes may be ascertained without
‘difficulty, as the fine lines of silk proceeding from
em will be distinctly perceived. Mr. B.’s
_ Obse: s were made on Agelena labyrinthica
— (Walck.)—Ep.
Sei geor. 1.

weeee

‘40°. 24:47 ©

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4
{

— =

ARACHNIDA.

dividuals.

20%
finger, is composed of an immense number of
minute filaments, perhaps many thousands, of
such extreme tenuity that the eye cannot detect
them, until they are all twisted together into
the working thread. Lyonnet has made a still
more curious observation: he detected in Tege-
naria civilis (Walck.) a different anatomical
structure of the four spinnarets. The pair
which is above and a little longer than the
other, presents on its surface a multitude of
small perforations, (fig. 97,) the edges of
which do not project, and which, therefore,
‘ig. OT. resemble a sieve. This
ZB structure has _ also
300 0 been welldescribedb

Leuwenhoeck, Roe-
sel, Treviranus, &c.
The other pair, shorter
and lower than the
preceding, differs still
further by having pro-
jecting or mamillary
tubes independent of

the perforations which also exist and are analo-
gous to those above de-cribed. The tubes are
hollow,and perforated at the extremity (fig. 98, a).
Lyonnet supposes that agglutinating threads
issue from these tubes, while those which are

Fig. 98.

emitted from the per-
forations do not poss-
ess that property. We
may observe, indeed,
upon throwing a lit-
tle dust on a_ spi-
der’s web, such as the
circular one of aranea
diadema, that it ad-
heres to the threads
whicharespirally dis-
posed, but not to those that radiate from the
centre to the circumference; the latter are also
stronger than the others.

Fig. 99.

a a

Internally there
exists in the abdo-
men of spiders a
special secretory ap-
paratus, which con-
sists of intestiniform
canals, united toge-
ther, and variable in
number and extent
6 according to the
species. In Clu-
bione atrox, they
consist, according
to Treviranus, of
four vessels, two
large (fig. 99, aa)
and two small (bb);
near their base, and
not far from the
point where they open into the spinnarets, a
number of small supplementary canals (cc)
may be observed. ( Fug. 96 represents the spin-
narets in the same species.)

Generative system.—In the arachnidans the
sexes are placed, as in insects, in different in-
It is not always an easy matter to

distinguish outwardly the male from the female ;
P

210

but in some cases there exists a well-marked
character. The greater part of the aranee of
the male sex have, at the extremity of their
maxillary palp, a swelling containing a compli-
cated structure, which is not found in the
female. Until lately this protuberance was
considered, notwithstanding its anomalous po-
sition, as the penis of the male; and even now
this opinion is maintained by many naturalists.
All observers indeed, both ancient and mo-
dern, agree in stating that copulation takes place
by means of this part. They have repeatedly
observed the fact, and have described the pro-
cess with all the details that can inspire con-
fidence in their observations. Nevertheless
it appears to us certain, if the anatomical facts
we are about to disclose are accurate, that there
is some mistake on their part, and that what
they have taken for the act of copulation was
in reality only a prelude to it. It is indeed
true that the male spiders are distinguished
from the females by the swelling at the extre-
mity of the maxillary palp, and that that swel-
ling presents a very complicated structure.
Treviranus, Savigny, and, earlier than these,
Lyonnet, have given detailed figures of it, which
may be consulted with advantage: our descri
tion will be after that of Treviranus, and from
observations made on the common spider, ‘'e-
genaria domestica.

The male of this species, when arrived at the
adult state, presents a considerable dilatation at
the extremity of its maxillary palp (fig. 100, a).
On carefully observing this swelling, it is per-

ceived to arise from the
penultimate joint (6),
which is enlarged and
spiny. The swelling it-
self, or what has been
termed penis, (fig. 100
and fig.101, a,) isa con-
cave body from which
a membranous, © vesi-
cular, and glandiform
body (c) protrudes, ter-
minated by _ several
horny pieces (d), which
a are curved and pro-
NAH ne «ject but slightly in
hs this species, but ac-
quire, in others, a con-
siderable development,
and protrude in the form
of long hooks having a
much greater complication of structure.
Fig. 101. In order that this
Li part should be a
penis, as has been
supposed, and as
many __ naturalists
still believe, it ought
to be perforated for
the emission of
the prolific liquor.
Now, Treviranus is
certain that it is not
perforated by any
foramen, and also that there does not exist in
the interior of the palp any excretory duct

ARACHNIDA.

which could have brought to this pe the secre _
tion of the testicles. Lastly, and this proof is —
still more conclusive, on examining carefully
the under surface of the abdomen of a male, he
discovered at its base, i. e. at the point where it
is inserted into the thorax, between the aper-
tures of respiration, and at the part correspond-
ing to the vulvary opening of the female, two
very small orifices, placed in a transverse fissure,
which he ascertained to be the true outlets
of the male apparatus. He found in the inte-
rior of the abdomen two cylindrical dilated
vessels, which he determined to be the testes.
( Fig. 102, b, b.) These two organs open into
_ two long, slender, tortuous,
excretory canals (c), which
terminate at the two orifices
of which we have spoken
(a), but without theappear-
ance of any superaddition of
a firm or horny part that can
be compared to a penis.
From this description it is
certain that what has beer
- regarded as the act of copu-
lation, has been only preli-
minary, and that the intro-
duction of the extremity of
the maxillary palp of the
male into the vaginal aper-
tures of the female was forthe
mere purpose of opening the
oviducts in order that the ac-
tual coitus should be effect-
ed with facility and with-
out doubt instantaneously ;
which explains why no ob-
server has hitherto witness-
ed the act.*

The remarkable sexual
differences which obtain in
the aranee are not found in
other arachnidans. Thus
in the scorpions the maxil-
lary palps have a similar organization in both
sexes, being terminated by pincers, both in the
male and female, (fig. 84, 6.)

The external aperture of the male apparatus
is placed behind the thorax, and manifests itself
by the presence of a valve formed by two semi-~
circular pieces (fig. 84, c..) The internal struc-
ture of these organs is but imperfectly known.
Treviranus believes that he could distinguish
the testicles which terminated at the extremity
in a kind of horny penis. Leon Dufour has
given a more detailed description of these or-
gans, together with a figure which represents
each testis, as being a large network of three
meshes formed by cylindrical tubes. |

The male, like the female scorpion, presents —
at the inferior part of the body on either side of

Fig. 102.

ee a ee

* Mr. Blackwall denies the accuracy of Trevi-—
ranus’s opinion, and supports that of Lister and t
older observers, as to the sexual function of t
maxillary palp, founding his remarks on obser
tions made on various individuals of the genera
Epeira, Theridion, and Agelena. We must refe:
for the details to the memoir before quoted from the —
Transactions of the Linnean Society.—ED. .

ARACHNIDA.

the valve certain organs of a singular structure
which are called combs, pectines, (fig. 84, d, )
on account of the disposition of a series of
small appendages of which they are formed,
and which are arranged on the lower surface
one beside the other, like the teeth of a comb.
Many speculations have been offered respecting
their uses. Many naturalists believe that they
render some assistance in the act of impregna-
tion. Some suppose that they are extended
during progression, and prevent the abdomen
of the scorpion from trailing on the ground :
others, again, regard them as hygrometrical
organs, by means of which the animal judges of
the humidity of the atmosphere. These are,
however, all mere gratuitous hypotheses un-
supported by any observation ; and the fact is
that we have yet to learn the use of these pec-
tinated appendages.

Of the female generative system.—It has
been long known that the orifices of the gene-
rative organs in female spiders are situated at
the base of the abdomen. We observe on that
part of the body two distinct cavities, (fig. 103,
a, a,) which are closed by opercular pieces of

Fig. 103.
2 =
NICE
(cso ° a c oe x j
t a= Bf ==
ae sie . b
(a ,

a more or less solid texture, and it is at this
part that the oviducts terminate. In the tege-
naria domestica, these oviducts (6, b) are con-
tinued internally in an insensible manner with
the ovaries, which consist of a kind of bags
(c, c) situated on each side of the intestinal
canal, and to whose parietes the ova are attach-
edinaracemose manner. In the epeira diadema
the ovaries are divided by two longitudinal
membranous septa, and each is again subdivided
by a transverse septum. The longitudinal sep-
tum has no orifice, but the transverse one is
perforated. There is, therefore, no communi-
cation between the principal chambers of each
of these ovaries, but there is a passage from the
anterior to the posterior division, and the ova
which are in the former must pass into the lat-
ter before being extruded. This structure ex-
lains how it happens that the epeira diadema
Ys its eggs at two distinct periods. Another
Spider (theridion quadripunctatum, Walck.)
presents a very analogous organization.
The female generative apparatus of scorpions
has not hitherto been studied with that degree
of care which it deserves; and there is a consi-

211

derable difference among authors with respect ©
to this subject; it therefore requires farther ex-
amination. Treviranus and Leon Dufour have
described these organs as consisting of three
elongated tubes; of these, two are lateral and
mutually communicate at their apices, the third
is mesial and communicates with the lateral by
three branches which we observe on either side.
All of them, lastly, terminate at the vaginal
orifice which is concealed by a more or less
rounded plate, and is situated on the middle
line of the body anterior to the pectines and ~
between the coxe of the fourth pair of legs, at
the same point where the penis is placed in the
male (fig. 84, c.)

Copulation, oviposition, and development of
theova. Metamorphosis, and reproduction of the’
extremities—Natural observers have hitherto
given but very few details respecting the man-
ner in which the male spider approaches the
female, in accomplishing the sexual act: and
wehave already observed that they have been de-
ceived in considering a preliminary step as the
entire process. The preliminaries are accom-
panied with very curious circumstances, the
account of which may be found in all. the me-
moirs and works which treat of the animals of
this class. It will be there seen with what
precaution and fear the male makes his ap-
proaches to the female, who is always ready to
attack and devour him, whether before or after
copulation. The majority of the arachnidans
deposit their eggs in great nuinbers. The
female guards them with the utmost care, some-
times carries them about with her, and always
prepares a silken nest for them which is fre-
quently covered with a solid exterior. Some
arachnidans, as the scorpions for example, are
Ovo-viviparous; the ova are developed in the
interior of the body of the female who brings
forth her young possessing the faculty of loco-
motion; but they rest for a certain time at-
tached to the back of the mother, who guards
and feeds them, and gives them a kind of edu-
cation.

The changes which occur in the ova of
spiders (aranez) have been studied with much
care. We are indebted to M. Heroldt for
highly interesting observations on this subject,
published in the work entitled “ Exercita-
tiones de animalium vertebris carentium in
ovo formatione,” folio, Marburg, 1824, from
which an extract is given in the Annales
des Sciences Naturelles, first series, vol. xiii.
p- 250. From the importance of these re-
searches we here present an analysis of them.

The exterior covering of the ovum is formed
by a very delicate and transparent membrane,
in the composition of which no pore or fibre
can be distinguished on microscopical in-
spection.

Within this membrane there is a liquid
matter in which Heroldt has distinguished
several essential parts, which in relation to
their functions appear to us to correspond to
the vitellus, the albumen, and the cicatricula
of the egg in birds. An idea of the disposi-
tion and size of these parts may be formed
by inspecting the subjoined figure ¢ ‘fig. 104),

: P

representing a vertical
section of a fecundated
ovum at the moment
ofexclusion,and before
any organ has been de-
veloped. The vitellus
or yolk (@) forms the
| greatest part of the
contained liquid mat-
ter, and the egg is
almost entirely filled by it: its colour is gene-
rally that of yellow ochre, and sometimes has
a saffron tinge. In some species the yolk is
grey, white, or reddish brown; and in each
case the colour of this part determines the ge-
neral tint of the egg. If the yolk be consi-
derably magnified, it isseen to be composed of
an infinite number of minute globules of various
sizes, swimming in the albumen, or surrounded
by it, and resembling so many small yolks.
The albumen (b) is a transparent crystalline
liquid, without distinct organical parts, and
consequently not presenting any globules, sur-
rounding the vitellus as far as the cicatricula,
and intermediate in bulk or quantity to these.
If an ovum be opened, and the liquid which
it contains be poured out upon glass, the albu-
men is seen to surround the globules of the
vitellus and cicatricula exactly as the serum
of the blood envelopes the crassamentum.
In the interior of the egg the albumen is
situated, like the cicatricula, externally to the
yolk, and fills the interspace between the yolk
and the exterior membrane of the egg. It is
in this interspace that the first lineaments of
the embryo appear, and here the head, thorax,
members, integuments, and their appendages,
and all the internal organs, without excepting
the intestines, are successively developed.
_ The cicatricula or germ (c) is the smallest
and most important part of the ovum. It is
situated immediately beneath the exterior co-
vering, and at the centre of the circumference
of the egg. It is distinguished by the naked
eye in the form of a little white point. If it
be examined with more care, we perceive that
it is of a lenticular figure, and is composed
ofan innumerable quantity of whitish granules.
Under the microscope these granules are seen
to be of a globular figure, somewhat similar in
this respect to those of the yolk, but more opake,
and of a smaller diameter. When segregated
and diffused they present a striking analogy
to the grains of pollen, but with this difference,
that the pollen of vegetables is composed of
vesicles filled with organic molecules, whilst
each of these globules of the cicatricula must
be regarded as simple. The cicatricula or
germ is the centre of radiation of all the
changes which take place in the ovum. All
the parts which it contains seem subordinate
to it, as we shall see by carefully tracing their
development. A remarkable fact observed by
Heroldt in the ova of some undetermined
species of spiders is this, that in place of a
single cicatricula, there appear to be several
spread over different points of the surface of
the ovum; but these small germs rapidly
coalesce into one mass, which soon assumes

i

MI
Hl
|

\

a

ARACHNIDA.

i in

the ordinary form of the single cicatricula.
The component parts of the ovum being known, J
we proceed to the metamorphoses which they
undergo up to the time when the young spider
breaks through the shell.

First period.—The im-
pregnated ovum being de-
posited, and the temperature
being favourable, develop-
“i@), ment commences. The
wo changes always begin at
¥ the margins of the cica-
tricula, which appear to be
resolved into granules,which
extend into the albumen and
vitellus. The centre of the germ remains the
same, the only appreciable difference is the
enlargement of its circumference: (A, gives
the natural size of the ovum.)

Second period.—The germ is much larger,
its margins are dispersed in numerous granules ;
the centre is not yet affected by this tendency
to molecular dispersion, but has undergone
a notable modification. It changes its situation
and begins to move towards the extremity of
the ovum, leaving in the place which it for-
merly occupied a train of globules; it now,
to compare small things with great, bears some
resemblance to a comet, the nucleus of which is
represented by the centre of the germ; the tail,

_— Tv

————

‘which is formed by the dispersion of the globules,

is transparent, and the vitellus which it covers
may be as distinctly seen through it as the fixed
stars through the tail of a comet.

Third period.—The nucleus of the germ é
(fig. 106, a), which has continued to change its .

Fig. 106. place, is arrived near the
AG extremity of the ovum, but
has not quite reached it.
The tract which it has
traversed is marked by an
infinity of granules, which
are then so much dissemi-
nated that they extend al-
most to the opposite extre-
ees mity of the ovum. It is
then that the kind of comet which it represents
is seen at its greatest development, and with all
the characters that have been indicated. The
movement of the nucleus of the cicatricula
authorizes the supposition that that body has
not, at least at the earlier periods, a very
intimate connexion with the vitellus.

Fourth period.—The nucleus of the germ
has not gone beyond the point which it had
attained, but it presents a new change. The
molecules are disseminated into an infinity of
granules; nothing remains of the comet but
the tail, which is still more extended; but
we see then that the granules dispersed in
the albumen have a tendency to reassemble at
the point where the germ was originally situated.

Fifth period.—The germ of the ovum, which —
appears to be disseminated in the albumen, —
has undergone a very curious transformation. —
Its nucleus has disappeared, all its granules”
are decomposed into almost imperceptible mo- _
lecules, which, in destroying the limpidity of —
the albumen, have given it a clouded appear- —

ARACHNIDA.

ance, through which, however, the globules
of the vitellus may be distinguished. A single
point remains perfectly transparent, and this is
observed at the extremity of the egg (fig. 107,
a,) opposite to that which the germ occupied

Fig. 107.

after its displacement.
Heroldtcalls this clouded
albumencolliquamentum.
Up to this period the
vitellus seems not to un-
dergo any change; all
that has been hitherto
observed takes place in
the albumen and in the
- circular space between
the yolk and the shell.
Sixth period. — The colliquamentum, or
clouded albumen, which was extended over
the yolk so as to conceal it, is now concen-
trated upon the point last occupied by the
nucleus of the germ, and has assumed a pearly
colour (fig. 108). Its consistence is pretty
Fig. 108. solid ; it is opake, so that

: the globules of the yolk

*can no longer be distin-
guished through it, al-
-4_» though they are elsewhere
more conspicuous on ac-
count of the retreat of the
clouded albumen towards
this single point; from
see this moment the colliqua-
mentum, which seems to have changed its
nature, receives a new name, and is designated
by Heroldt the cambium. Thecambium covers
more than a fourth part of the circumference of
the yolk; its form is already pretty well marked,
and two parts may be distinguished in it;
one large (6), the other small (a), which are
Separated by a kind of contraction. The form
of the larger division is elliptical, and it is in
its substance that the thorax, the legs, and the
essential internal parts of the foetus will soon be
perceived to develope themselves. The smaller
division is of a rounded form, and seems, as it
were, an appendage to the preceding; it is
destined 1o give origin to the head, the or-
gans of sense, and the appendages of those of
mastication. So much being premised, we
may call, with Heroldt, the larger division
cambium thoracicum, the lesser one cambium
cephalicum. We may also, for the better
comprehension of the changes which are about
to succeed each other, divide the supertficies
of the ovum into four regions. That which
contains the cambium may be called the pectoral
region, the opposite portion may be called the
dorsal, and the two intermediate parts the
lateral regions. We may observe that in other
> of aranee where the ova are spherical,
germ is at once converted into colliqua-
mentum, and then into cambium, without a
change of situation. The Aranea diadema offers
an example of this circumstance; in other re-
spectsthereis no important difference observable.
Seventh period—The two portions of the
cambium, the cephalic and thoracic, have
as yet presented only the appearance of an
opake and homogeneous mass, but now we

213
may distinguish traces of rings, four in number
on either side; these are the rudiments of the
legs. ( Fig. 109, 1, 2, 3,4.) They occupy the
lateral aspects of the
anterior part of the
ovum; they are also
visible on the pectoral
region, towards which
they are prolonged in-
feriorly. The extre-
mity of the first leg is
contiguous to that of
the opposite side; but
the three others, though
of greater length, yet
do not reach so low down, but leavea triangular
interspace between them, which is filled with
a cloudy and somewhat transparent matter,
through which the vitelline globules are visible.
This triangular space, which is subsequently
to be covered by the legs, seems to give origin
to the trunk and to many parts contained in
the abdomen. In tracing the two portions
of the cambium through the changes which
they have undergone, we find that the thoracic
portion is represented by the legs and their
intermediate space, and that the cephalic por-
tion is anterior to this. The alterations of the
latter part are not less remarkable; instead
of being rounded anteriorly it is truncated, and
we may perceive a ring at the sides, which is not
divided on the inferior middle line of the body,
and which represents the maxillary palps (0).
One may even distinguish, as if through a
cloud, the rudiments of the mandibles. It
is probable that all the parts which appertain,
to the head, as the eyes, the mandibular
hooks, and the maxillw, have their limits well
defined from this period. With respect to the
head, (a) it is neatly separated from the chest ;
and this fact it is of importance to dwell on,
since in all the full-grown spiders the conflu-
ence of the two parts is most intimate, and their
original separation only indicated by a groove
of greater or less depth. The ovum, also,
now presents some other new appearances ;
these are a kind of furrows or arched folds
(c c), which are seen on the vitellus behind
the legs; and which deserve attention, since
they indicate the formation of the common
teguments of the fetus. And we must here
observe that the parts which are already de-
veloped have an intimate connection with the
vitellus. Thus if an ovum be opened with
all the precautions requisite for so delicate an
operation, and if the matter of it be extended on
a piece of glass, we see that the parts formed
in the cambium preserve their general figure,
and that the internal layer of the mucous and
whitish matter of which it consists is in intimate
communication with thevitellus. It is implanted
upon the yolk just as fungi and other parasitic
plants are attached to the trunk ofa tree: the
yolk, then, is subservient to the nutrition of
the most exterior parts of the body.

Eighth period.—The exterior parts which are
developed in the cambium, viz. the feet, the
mandibles, and the head, are more neatly de-
fined. The ovum (fig. 110) now presents a.

t
*

214

very important pecu-

liarity, but which was

in some measure in-
dicated in the pre-
ceding period. Its

size is slightly di-

minished anteriorly,

and the vitellus con-
sequently is divided
- into two portions.
The smaller and an-
terior part (a) is rea-
dily distinguishable
from the dorsal part
of the foetus, and occupies the place which sub-
sequently becomes that of the corslet; M.
Heroldt consequently terms it the thoracic re-
gion. The other part is the abdominal region,
which is very conspicuous, occupies more than
one-half the bulk of the ovum, and seems to
constitute the greatest portion of the abdomen.
If the inferior surface of the abdominal region be
examined, there will be seen, in addition to a
spot which ornaments that part, some addi-
tional oblique and curved folds, which indicate
the formation of the integuments; another and
a more important change has now taken place
on the middle line of the superior surface; viz.
an obscure straight band (b.) which commences
at the thoracic-abdominal constriction, and
reaches to the extremity of the ovum, becoming
gradually narrower in that direction. This
band, which does not give off lateral processes
in any part of its course, is to be considered as
the rudiment of the heart or dorsal vessel. The
fluid which it doubtless contains in its interior
is motionless. Heroldt thinks that the forma-
tion of the fluid is anterior to that of the
parietes in which it is enclosed : he also be-
lieves that it is the albumen which gives origin
to the circulatory apparatus, and further attri-
butes to it the origin of all the integuments.
These are, doubtless, important questions to
solve, but as they are the result of speculation
rather than direct observation, we have deemed
it proper to omit the theories by which they are
supported, and confine ourselves to a simple
enunciation of the facts The eyes (d) are
now distinguishable.

Ninth period.—The ovum presents a more
sensible diminution anteriorly, and is more dis-
tinctly divisible into two parts. The anterior
and narrow portion constitutes the smaller ex-
tremity, and includes the head, the thorax, and
their appendages ; the other portion, which is
spherical and of much larger size, constitutes
the greater extremity and corresponds to the
abdomen. At the same time that these modi-
fications take place the ovum becomes slightly
elongated, and a!l the parts which can be dis-
tinguished therein have proceeded towards
their perfection. The legs new present slight
traces of a division into joints, and they have
increased so far in length that they cover almost
the whole of the lower surface of the thorax.

Tenth period.—The small extremity, which
is still more elongated, is now found to be dis-
tinguished from the large one by a true con-
striction, dividing the ovum into the parts de-

Fig. 110.

ARACHNIDA.

nominated in the perfect spider ¢ thorax’ and
‘abdomen.’ The visible parts of the thorax
are the mandibles, the palpi, and the legs;
these latter appendages are folded upon the
chest, and have grown so long as to cross the
middle line of the body; they are locked in the
interspaces of each other, like the fingers when
the hands are clasped together. The abdomen
presents nothing remarkable, except the elon-
gated opake streak which exists along the middle
of the inferior surface from the feet to the term1-
nation of the abdomen, and which was already
visible at the preceding periods. ( Fig. 110, e.)
Heroldt imagines this streak to be an indication
of the development of the internal parts of the
abdomen, viz. the intestinal canal, the secreting
vessels of the web, and the genital organs, &c.
In proportion as the foetus increases, the ex-
ternal membrane or covering of the egg is ap-
plied more exactly to its body, and seems to
represent an exterior skin, of which the young.
spider soon divests itself, almost in the same
manner as the caterpillar sheds the skin in
which it is enveloped.

Eleventh period.—By the progressive in-
crease of the foetus the membrane of the egg
becomes so much stretched, and is applied so
exactly to the surface of the body of the animal
that the different parts can be distinctly seen
through it, like the nymph or chrysalis of certain
coleopterous insects. The essential parts of the
thorax are the head and the feet. The head is of
a white colour, and is surmounted by eight
brown streaks ; the legs, which are also white,
are closely applied to the chest, with their extre-
mities alternating with each other. One may dis-
tinguish in each a hip,a thigh, a leg, and a tarsus.
The articulations of the palps and mandibles
are also visible through the general envelope of
the egg. The inferior streak of the abdomen
is much more extended, and seems to be divi-
ded into two parts, one large and elliptical in
figure, the other small and rounded; the latter
corresponds to the anal aperture; at this last
stage of the development, the foetus or the im-
prisoned young spider, as it may be called,
gives no sign of motion.

Exclusion or hatching of the spider.—At
length the spider bursts the egg by tearing
through the exterior membrane. De-Geer* has
described this phenomenon. The outer mem-
brane or pellicle of the ovum becomes fissured
along the corslet, and the spider protrudes by
this aperture, first the head, the mandibles, the
thorax, and abdomen, after which there remains
the more difficult operation of extracting the
legs and maxillary palps from that part of the
outer membrane with which these parts are, as it
were, enveloped. This is.at length effected,
though slowly, by alternately dilating and con-
tracting the body and legs, upon which the —
animal is liberated, and capable of progression. —
In proportion as the parts are disengaged from —
the pellicle, it is pushed towards the extremity
of the legs, and is reduced toa little white bag”
which is all that remains. Sometimes the pel-—
licle is found still slightly adherent to the ab-—

es SO

aoe

* Mém. sur les Insectes, t. vil. p. 195.

_— ="

ARACHNIDA. 215

domen, but the spider soon entirely frees itself
from it. This is the mode in which the young
spiders of every species disembarrass themselves
of the egg-covering, and the operation is analo-
gous to that of moulting. This is, however,
only the first birth : all the parts of the spider,
the head, the jaws, the legs, the abdomen, are
still enveloped by a membrane which furnishes
to each a sort of sheath. The spider is embar-
rassed in all its movements; it changes its
situation with apparent pain, and is unable to
construct a web and seize its prey: it seems in-
deed to be stupified and indisposed to action.
To this end, and in order to be fit for locomo-
tion, it is necessary that it should free itself of
this other covering ; and it is only then that it can
be said to see the light. This last operation,
or as it may be termed the first moult, takes
place after a period, varying according to the de-
grees of atmospheric heat and moisture. Some-
times it is observed within the first week, at
others it is not effected before the end of several
weeks. In every instance the moult takes
place in the woolly nest or general envelope of
all the eggs, and the young spider does not
quit this common nest, except in fine weather,
generally in the months of May and June.
Before arriving at the adult state the spider
changes its skin many times, and even after that
period it is still subject to moults, which occur
every year in the spring, and after the exclusion
of the eggs. Up to the present time it has
been admitted that the Arachnidans, from the
moment of their exclusion to their adult state,
undergo no metamorphosis, but are subject
only to the moultings of which we have just
spoken. This circumstance has even been em-
ployed by zoologists as a character distinguish-
ing the arachnidans from the class of insects,
which generally undergo metamorphoses in pas-
sing through the conditions of the larva and
chrysalis. The observation holds good for the
greater part of the Arachnidans, but there are
many of this class, which, in passing to their

adult condition, undergo changes which cannot

but be compared with the metamorphoses of
insects. Such, for example, are many of the
acaride, wpon which M. Dugés has recently
fixed the attention of naturalists.*

We cannot conclude the present article,
without briefly noticing a very curious phy-
siological phenomenon which has been ob-
served in the Arachnidans, and which has
long been noticed in the class Crustacea :
we allude to the faculty which these animals
—— of reproducing their limbs when these

ave been accidentally lost. This property,
which belongs to the spiders, (aranee,) was
generally doubted, until a distinguished natu-
ralist, M. Lepelletier, published the result of
his experiments; the fact is of too much im-
portance in science not to be dwelt upon with
some detail. Spiders which have lost a limb,
according to this observer,} are always found

* See his interesting Memoir in the Annales des
Sciences, Nouv. Serie, tom i. and ii., 1834,

t+ See Bulletin de la Societé Philomathique,
Paris, Avril, 1813, ~

to have lost it entirely, that is, the femur, tibia,
and tarsus, are all wanting. A portion ofa leg is
never found detached at one of its joints, nor bro-
ken off between twojoints, nor the femur remain-
ing adherent to the body by itself, or with the tibia,
the rest of the leg being lost. If by accident a
spider should be met with in any of these con-
ditions, it is either dying or dead. But M.
Lepelletier remarks that those which have lost
one or more entire legs, are not less lively on
that account.

To explain these circumstances our author
commenced a series of experiments on spiders,
in the year 1792, with the following results: —

The smallest wound in the thorax or abdo-
men of a spider is mortal, and that in a very
short time, on account of the loss of the internal
nutrient fluid, which cannot be staunched.

If a‘leg of a spider be cut off with a sharp
instrument either at one of its joints, or in the
interval of two, leaving a part of the limb ad-
hering to the body, the spider appears to suffer
considerably ; it endeavours to tear off the rest
of the leg; if it succeeds, it again acquires its
powers of moving, and the hemorrhage soon
ceases; in the contrary case it perishes in
twenty-four hours.

The luxation of one of the joints, or the frac-
ture of the femur or tibia in the middle are
equally mortal, if the spider does not soon dis-
embarrass itself of the leg which has received
the injury.

It is necessary here to make a remark upon
the anatomy of the legs of spiders and crusta-
ceans ; they have the first joint short, which
connects the leg to the thorax; M. Lepelletier
calls this the haunch, cora. If a spider be
seized by the extremity of one of its legs, and
is left at liberty to make its efforts to escape,
the leg will be separated from the body at the
junction of the femur with the cora; and the
same thing takes place when the body of the
spider is held fast, and the leg is pulled off. In
both these cases the spider seems not to suffer
pain ; it experiences only a very little loss of the
internal fluid, and does not die in consequence ;
it spins, seizes its prey, and oviposits in the or-
dinary manner.

The preceding facts are applicable to all
spiders, (aranee@,) and M. Lepelletier has ob-
served them repeatedly in many of the common
species. The following experiments have been
made only on the domestic spider, ( Tegenaria
domestica, Walck.) because it can be preserved
in a lively condition, and for many years in a
glass vessel.

We have successively observed a great num-
ber of individuals of this species which were
mutilated of one or more legs. It was not
without surprize that the author of this article
observed the first spider that was experimented
upon, and which wanted a leg, change its skin,
and after that operation reappear with eight
legs. The like occurrence was frequently ob-
served ; the new leg was two or three lines in
length when it first appeared, that of the oppo-
site side being less than an inch: each of the
joints of the former continued to grow during
the whole of the year.

216

-

The general result of these observations, and
of many others of the same kind, is, 1st, that
the legs of spiders can be reproduced when
they have been torn off; 2d, that this repro-
duction can only take place when the limb has
been detached as high as the moveable base ;
for otherwise an hemorrhage supervenes which
kills the animal; 3d, that the reproduction
takes place only at the time of the moult, and
that the new leg is at first slender, but with all
its parts or joints, each of which increases pro-
gressively, until the whole has acquired its

natural relative size.*

BIBLIOGRAPHY.—Lister & Way, Obs. concerning
the darting of spiders, Phil. Trans. 1669 and 1670.
Homberg, Sur les araignées, Mem. de Paris, 1707.
Clerck, Vom fangen und Ernahren der Spinnen Abh.
d. Schwed, Akad. J. 1761. Boissier de Sawvages
Obs. sur une araigné, Mem. de Paris, 1758. Ha-
gedorn, De Araneis, Miscel. Acad. Nat. cur. Dec.
II. an 3, 1684. Valentini, Curiosa in araneis ob-
servata, ib. Dec. ii. an 7, 1688. Dorthes, Obs. on
the structure and economy of some Curious species
of aranea; Trans. of Linn. Soc. vol. ii. Paullini,
De aranea rara, Misc. Ac. Nat. cur. Dec. iii. an 3,
1695. Garmann, Aranea aere nutriantur ib. Dec. i.
an 1, 1670. Wurmb, Beschryving van te groote
tuin-spin van t’Eiland Java; Verhand. v. h. Bataaf.
Genoot. Deel 3. Latreille, Sur la famille des
araignées mineuses, Soc. Philomathique, an 7.
Prevost, Sur les araignées mineuses: Mem. de la
Soc. d’Hist. Nat. de Paris, Cah.i. Martyn, Aranei;
or, a natural history of spiders, 4to. Lond. 1793.
Hahn, Monographie der Spinnen, 4to. Nurnb.
1820-22. Ej. die Arachniden liv. 1—10. Clerck,
Aranei Suecici, 4to. Upsal. 1757. Muel/er, Hydra-
rache quas in aquis Danie, &c. 4to. Lips. 1781.
Lister, Hist. Animal. Anglia, 4to. Lond. 1678;
Germanice cum add. a Martini et Goeze, 8vo.
Quedlingb. 1778. Meyer, Ueber ein. Spinnen d.
Gotting. Gegend. 8vo. Gotting. 1790. Treviranus,
Ueber den innern Bau der Arachniden, 4to. Nurn-
berg, 1812. Heroldt, Exercit. de animal. verteb.
carent. formatione in Ovo Pars prima: De genera-
lione aranearum, fol. Marb. 1824. Walckenuer,
Faune Parisienne, 2 tom. 8vo. Paris, 1802; Ej.
Tableau des Aranéides, 8vo. ib. 1805; Ej. Hist.
des Aranéides, Fasc. 5, 12mo.; Ej. et de Blainville,
&c. Aranéides de France. Lyonnet, Rech. sur
Vanatomie et les metamorphoses de differentes és-
poces d’insectes, 4to. Paris, 1832. Roesel, Insecten-
Belustigungen, 4 tom. 4to. Niirnberg, 1746.

(Victor Audouin. )
ARM. (Surgical anatomy.) (The arm, Gr.
Beayswy. Lat. Bruchium. Fr. Bras. Germ.

Oberarm. Ital. Braccio.) The ancients ap-
plied this term to the whole of the upper
or thoracic extremity collectively, as most
persons do in ordinary discourse, at the
present day; but in anatomical language the
term is restricted to that section of the upper
limb included between the shoulder and the
elbow. The arm taken in this limited sense
is somewhat cylindrical, a little flattened,
however, on its internal and external surfaces,
particularly towards its middle; it varies

* Mr. Blackwall, in the paper already referred to,
has related an accidental discovery of the power of
some spiders to abstract respirable air from water.
Several individuals have preserved an active state
of existence under water for six, fourteen, or twenty-
eight days, spinning their lines and exercising their
functions as if in air, while others have not sur-
vived for a single hour.— Ep.

2

ARM.

much in its proportions as to length and
volume: it is more rounded in fat persons,
and especially in females, in whom it assumes
more or less of a conoid form, ing to-
wards its lower part. (See fig. 1 and 2, p.3.)
The arm is composed of a single bone, the
humerus, several muscles, bloodvessels, ab-
sorbents, and nerves connected together by
cellular tissue, and inclosed in an aponeurosis,
which lies immediately beneath the common _
integuments. Viewing the arm extended, the
hand being placed in a state of supination,
we observe at its superior and external part
a prominence of a triangular form, the base ;
of which is superior; this is formed by the
deltoid muscle, and is bounded before and
behind by two slight grooves, which unite d
below in a depression called deltoid fossa, :
situated immediately over the insertion of the E
deltoid muscle; this deltoid fossa is the most
eligible part of the arm for the insertion of
issues, as it contains a considerable quantity
of cellular tissue, affording a favourable bed
for the reception of peas or other bodies in-
serted for the purpose of exciting suppuration,
while it possesses this additional advantage,
that no muscular fibres extend across it, whose
contractions might have the effect of deranging
the surface of the ulcer or the dressings neces-
sary to be applied to it, and thus causing an
unnecessary degree of pain. From the deltoid
fossa a superficial depression extends along the
outer edge of the arm, and terminates in the
triangular fossa in front of the bend of the
elbow: along the course of this depression
blisters are frequently applied by the Parisian
and other continental physicians in inflam-
matory affections of the thoracic viscera,
a mode of treatment not generally employed
in such cases by the physicians of this
country. Another depression extends along
the inner side of the arm from the axilla to
the hollow in front of the elbow, where it joins
the external depression. Between these two
depressions there is an oblong prominence an-
teriorly, formed by the biceps muscle, and a
more flattened prominence intervenes poste-
riorly, formed by the triceps which occupies the
whole of the posterior surface of the arm.

Skin and subcutaneous tissue. — The skin
covering the arm is soft and delicate; sebaceous
glands and hairs are not very evident on it,
especially in front; it is thicker and stronger,
however, on the posterior surface. The basilic
vein is generally visible at the lower part of
the internal brachial depression, and the pul-
sations of the brachial artery may be felt along
the whole of its course: the cephalic vein is
sometimes visible, especially in thin persons, —
along the course of the external brachial de- —
pression. As the skin of the arm is loosely —
connected to the subjacent parts, the edges of —
simple incised wounds in this region are ea
retained in contact. The subcutaneous
of cellular tissue or superficial fascia conta
more or less adipose substance, in ter abu
dance in women and children than in
and in greater quantity in the depressions
over the muscular prominences ; the filan

—_—s

Ys

ARM.

of the cutaneous nerves of the arm and the
superficial veins and absorbents lie imbedded
in it: thus the cephalic vein and twigs of the
external cutaneous nerve appear along the
outer edge of the arm, and along the inner
edge are found the internal cutaneous nerve,
the brachial branches of the second and third
intercostal nerves, the cutaneous nerve which
arises from the ulnar high in the axilla, the
basilic vein, and a few lymphatie glands,
which lie at from one to three inches above
the internal condyle.

Aponeurosis. — Beneath the subcutaneous
layer of cellular tissue lies the aponeurosis or
fascia, which invests the muscles and the deep-
seated vessels and nerves of the arm: this
fascia commences above at the superior attach-
ment of the deltoid muscle; externally and
internally it is continuous with the fascia,
which extends over the axillary space; descend-
ing along the arm it is strengthened hy ex-
pansions which it receives from the tendons
of the deltoid, pectoralis major, and coraco-
brachialis in front; and behind it derives an
accession of strength from the aponeurosis
which covers the infra-spinatus and teres minor,
and from the tendons of the latissimus dorsi
and teres major. Atthe lower part of the arm
the fascia is attached to the condyles of the
humerus ; laterally and posteriorly it is at-
tached to the olecranon, on either side of
which it is continuous with the fascia on the
posterior surface of the fore-arm. In front of
the elbow this fascia receives a fasciculus of
fibres from the tendon of the biceps, and
becomes continuous with the fascia covering
the anterior surface of the fore-arm. The
fascia of the arm varies in strength in different
parts; it is very indistinct over the deltoid,
thin but very fibrous on the posterior surface
of the arm where it covers the triceps; it is
much stronger over the biceps, and the thickest
portion of it is found along the inner edge of the
arm, where it covers the brachial artery and its
accompanying veins and nerves. A strong
aponeurotic septum passes in from the fascia
of the arm to each of the lateral ridges of the
humerus; these septa are called intermuscular
ligaments, and, together with the humerus,
divide the space included within the general
fascia into an anterior and a posterior sheath ;
the external intermuscular ligament extends
from the insertion of the deltoid to the external
condyle; the internal extends from the inser-
tion of the coraco-brachialis to the internal
condyle. Both intermuscular ligaments are
narrowest above, and grow broader as they
approach the condyles: their surfaces give at-
tachment to fibres of the triceps posteriorly
and to the brachieus anticus, supinator radii
longus, and extensor carpi radialis anteriorly.
The posterior sheath;formed as above described,
is chiefly occupied by the triceps muscle, be-
_ neath which, in the spiral groove on the pos-
terior surface of the humerus, lie the musculo-
spiral or radial nerve and the superior pro-
funda artery: this nerve and the anterior or
musculo-spiral branch of the superior pro-
funda artery perforate the external inter-
muscular ligament and enter the anterior

217

sheath of the arm to get between the brachiaus
anticus and supinator radii longus, while the
posterior branch of the profunda descends
within the posterior sheath to the back part
of the external condyle; the ulnar nerve and
the inferior protunda artery enter this posterior
sheath together at its internal side, about the
middle of the arm, and descend within it to
the back of the internal condyle. A considerable
branch of the brachial artery, the ramus anas-
tomoticus, perforates the internal intermuscular
ligament above the internal condyle, and enters
the lower part of the posterior brachial sheath.
The anterior sheath of the arm contains the
biceps, coraco-brachialis, brachizus anticus, and
the origins of the long supinator and long
radial extensor muscles; the external cutane-
ous nerve traverses this sheath, perforating the
coraco-brachialis above, and descending ob-
liquely outwards between the brachizus anticus
and the biceps it gets to the outer side of the
latter, between the tendon of which and the
supinator radii longus it pursues its course to
the fore-arm ; the radial nerve and the branch
of the superior profunda artery accompanying
it are to be found in the lower and external
part of the anterior sheath, which they enter
as above described: these lie deep between
the brachizus anticus and supinator longus.
Along the internal side of this anterior sheath,
through its whole extent, run the brachial
artery, and its two vene comites included in a
sheath proper to them, and accompanied by
the median nerve, which has very important
relations to these vessels: this nerve is external
to the artery above, crosses it in the middle
of the arm, and lies internal to it below.
Superiorly the ulnar nerve lies to the inner
side of the brachial artery, from which it se-
parates to enter the posterior sheath, as already
noticed; the internal cutaneous nerve, the
cutaneous twig of the ulnar nerve, and the
basilic vein for a short part of its course
before it enters the brachial vein, also lie within
this sheath; and deeply situated in its lower
part is the ramus anastomoticus magnus of the
brachial artery.

Developement.—In the progressive deve-
lopement of the upper extremity in the fetus,
the arm is formed subsequently to the hand
and fore-arm, and at an earlier period than the
shoulder. In men the deltoid is fuller, and the
biceps in front and the triceps behind are more
prominent than in women: the greater fulness
of these two latter muscles, with the smaller
quantity of subcutaneous fat, give to the male
arm a greater diameter from before backwards
than in the transverse direction; while the
more slender character of the muscles and the
greater abundance of subcutaneous fat laterally
cause the arm of the female to assume a more
rounded form. In the course of the brachial
artery two trunks are often found to exist, in
consequence of a high branching of that vessel,
which sometimes occurs even at the lower
border of the axilla: the supernumerary branch
in such cases is most frequently the radial;
in some instances it is the ulnar and less fre-
quently the interosseous or median artery of
the fore-arm. When this irregularity occurs, the

218 ARM.

brachial artery usually preserves its ordinary
relations to the surrounding parts, while the
supernumerary trunk lies to its internal side
and takes a more superficial course, some-
times getting above the fascia of the arm, as
we have witnessed in a few rare cases. It
occasionally happens that the brachial artery
divides at its commencement into two trunks,
which again unite at its lower part. It is ob-
vious that the surgeon, in performing operations
on this artery, should constantly bear in mind
that it is subject to the above-mentioned irre-
gularities, and that he should cautiously guard
against committing the error of including the
wrong vessel in his ligature.

The internal side of the arm in the middle
of its length is the most eligible place for
making compression on the brachial artery ;
here this vessel is superficial, so that its pul-
sation can be felt at once, whilst it has nothing
interposed between it and the bone but the
tendinous insertion of the coraco-brachialis
muscle. It happens, however, that the median
nerve lies immediately over the artery in this
situation, a circumstance which causes com-
pression of the latter to be attended with con-
siderable pain, and productive of injury to the
nerve if maintained for too great a length of time.

As the trunk of the brachial artery and
several large nerves traverse this part of the
arm, it is obvious that wounds in this region
are liable to be attended with more serious
consequences than those of any other part of
the arm. A wound in the posterior region of
the arm may be attended with considerable
hemorrhage, if it should happen to penetrate so
deep as to divide the profunda artery, or it may
cause paralysis of the extensor muscles of the
hand and fingers by dividing the radial nerve.

When the humerus is fractured, the con-
sequent derangement of the fragments varies
according to the part at which the bone hap-
pens to be broken; when fracture occurs im-
mediately above the insertions of the pectoralis
major and latissimus dorsi, the lower fragment
is brought inward towards the axilla by the
action of these muscles, and drawn upwards
by the action of the deltoid, biceps, coraco-
brachialis, and long head of the triceps, whilst
the extremity of the upper fragment is rether
turned outwards by the supra-spinatus. In
cases where the humerus is fractured imme-
diately above the insertion of the deltoid and
below the attachments of the latissimus dorsi
and pectoralis major, the deltoid will draw the
lower fragment upwards and outwards, whilst
the upper fragment will be drawn inwards
towards the axilla by the pectoralis major and
latissimus dorsi. If the bone be broken im-
mediately below the insertion of the deltoid,
little or no displacement of the fragments may
ensue, as the opposing forces exercised on the
superior fragment by the deltoid on the ex-
ternal side, and the pectoralis major and latis-
simus dorsi on the internal, pretty nearly
counterbalance each other; it more generally
happens, however, that the upper fragment is
turned outwards by the preponderating action
of the deltoid upon it, whilst the lower frag-
ment is drawn upwards by the action of the

biceps, coraco-brachialis, and triceps. Frac-
tures of that portion of the humerus which is
covered by the brachizus anticus in front and
the triceps behind, are often unattended by
any very obvious displacement, in consequence
of these muscles being inserted into both frag-
ments; fractures near the elbow are occa-
sionally followed by deformities presenting
some of the characters of dislocations of the
elbow, of which more notice will be taken in
the article ELpow.

General inflammatory enlargement of the
arm is rare; it sometimes appears as a con-
comitant affection with inflammation of the
veins of the arm consequent on the operation
of phlebotomy, in which case it not unfre-
quently happens that abscesses form along the
course of the sheath of the brachial artery ;
red streaks along the course of the lymphatics
and enlargement of the lymphatic glands are
sometimes present in consequence of disease
or inflammation affecting the hand or fore-arm.

Amputation of the arm below the insertion
of the deltoid may be performed either by the
circular incision or the double flap; when the
latter method is practised, the flaps should be
formed on the external and internal sides, by
which the more important vessels and nerves
will be included in the internal flap.

When circumstances require the performance
of amputation above the insertion of the del-
toid, the circular operation should never be
practised, for the following reason ;—in order
to obtain a sufficiency of covering for the bone,
the pectoralis major, latissimus dorsi, and teres
major would all be detached from their inser-
tions, a consequence of which would be that the
contractions of these muscles in opposite di-
rections, by drawing asunder the edges of the
wound, would not only render complete appo-
sition difficult in the first instance, but more-
over their continued action would have the
effect of converting the wound into an ulcer,
which it would be extremely difficult if not
impossible to heal; therefore, whenever we
have to amputate so high up, it is the more
judicious mode of proceeding to make a flap
including so much of the deltoid muscle as
will form a sufficient covering for the stump.
The importance of attending to the foregoing
circumstances was first pointed out by Louis,
the learned secretary to the French Academy
of Surgery.*

The arteries which require to be tied after
amputation of the arm below the insertion of
the deltoid are the brachial and inferior pro-
funda on the internal side ; on the external side
there are often two branches of the superior
profunda requiring a ligature, one of which
accompanies the musculo-spiral nerve, and the
other runs in the substance of the triceps.

When it becomes necessary to tie the bra-

chial artery on account of a wound or aneu-
rism, the varieties of its relation to the median
nerve should be carefully borne in mind; at
the upper part of the arm this artery has the
median nerve external to it, and the ulnar
nerve to its inner side; in the middle of the

* Mémoires de l’Academie de Chirurgie, tom. v. ‘

ARM, MUSCLES OF THE.

arm the median nerve crosses the artery in
general superficial to it, but sometimes under-
neath it, while in the lower part of the arm this
nerve is invariably on its inner side.

When called upon to expose the brachial
artery for the purpose of tying it, the surgeon
should recollect that the course of the artery
may be readily determined by a line drawn
from the coracoid process to a point midway
between the condyles of the humerus on the
anterior surface of the elbow; hence his in-
cision for the purpose of exposing the brachial
artery should = always Hic along the course
of this line and perpendicular to the axis of
the os humeri. (See BracuraL ARTERY.)

For BIBLIOGRAPHY, see ANATOMY (INTRO-

DUCTION, )
(John Hart.)

ARM, MUSCLES OF THE.—The mus-
cles which clothe the os humeri are part of the
deltoid, the biceps, coraco-brachialis, brachieus
anticus, the origin of the supinator longus in
front, and the triceps behind.

The deltoid belongs to the shoulder, and
will be described with the other muscles of
that part. (See Scaputar Recon.)

1. Coraco-brachialis (coraco-humeral ). —
The coraco-brachialis arises from the point
of the coracoid process, in common with the
short head of the biceps, tendinous in front and
fleshy behind ; it separates from the biceps at
its middle third, passes inwards, and is in-
serted tendinous into the internal surface of the
humerus a little above its middle between the
triceps and brachizus anticus.

This muscle has in front of it the deltoid
and pectoralis major, which cover and conceal
from view its upper part; behind it the tendon
of the subscapularis, the tendons of the latissi-

‘mus dorsi and teres major, the axillary artery,

the median and the external cutaneous nerves.
The latter nerve perforates the muscle about
its middle, and passes through its substance
to reach the outer side of the arm; hence the
epithet perforatus has been applied to this
muscle. The coraco-brachialis can carry the
arm forwards and inwards; when the humerus
is fixed, it can act upon the scapula, and by
depressing its coracoid angle, elevate the in-
ferior angle and separate it from the ribs.

2. Biceps flexor cubiti (scapulo-coraco-ra-
dial ).—This is a long muscle swollen in the
centre, divided above into two portions called
heads, one internal short, the other external
long. The internal or short head arises from
the coracoid process of the scapula in common
with the coraco-brachialis. The long head is
attached by a long slender flattened tendon to
the upper part of the margin of the glenoid
cavity, and is united by a dense cellular tissue
to the glenoid ligament. This tendon passes
over the head of the humerus, and enters
the groove between the two tuberosities in
which it is bound down by the fibres of the
capsular ligament of the shoulder-joint ; a pro-
longation of the synovial membrane also lines
the groove, and forms a synovial sheath for

_ the tendon ; the tendon terminates in a fleshy:

belly which unites with the short head to form

219
the large belly of the biceps; the muscle ter

minates below in a tendon, which, passing
over the brachizus anticus and the front
of the elbow-joint, sinks into a triangular
hollow between the pronator teres and supina-
tor longus to be inserted into the back part
of the tubercle of the radius ; but before it sinks
into this triangular space, it sends off from its
internal side an aponeurosis (the semilunar
fascia of the biceps), which is inserted into the
internal condyle, and the fascia which covers the
muscle at the inner side of the bend of the elbow.
The biceps is covered by the deltoid, the
pectoralis major, the fascia of the arm and
integuments in front; behind it lies on the
humerus, coraco-brachialis, brachieus anticus,
and the external cutaneous nerve; internal to
it lie the coraco-brachialis and brachial artery.
It bends the elbow and makes tense the fascia
of the fore-arm; it is also a very powerful
supinator of the hand by virtue of its insertion
into the radius. Ifthe fore-arm be extended and
fixed, it will depress thescapula on the humerus.
3. Brachieaus anticus ( B. internus, hume-
rocubital )—When the biceps has been raised
from its situation, we observe the brachizus
anticus deeply situated on the front of the arm ;
it arises by two fleshy tongues, one on each
side of the insertion of the deltoid; from the
whole of the anterior surface of the humerus,
and the internal intermuscular ligament which
separates it from the triceps, its fleshy fibres
pass downwards in front of the elbow, and
end in a broad tendon which is inserted into a
triangular roughness on the anterior surface
of the coronoid process of the ulna. This
muscle is covered in front by the biceps, supi-
nator longus, the fascia of the arm and integu-
ments, the musculo-cutaneous and median
nerves, the brachial artery, and the pronator
teres; behind it covers the front of the lower
part of the humerus and the elbow-joint. This
muscle is the most powerful flexor of the fore-
arm uponthearm. As Bichat remarks, flexion
of the fore-arm takes place directly if the bra-
chieus combines its action with that of the
biceps ; if either acts alone, the flexion isin the
direction inwards or outwards; inwards whenthe
biceps acts alone, outwards when the brachizus.
4. Triceps extensor cubiti (brachieus posti-
cus, tri-scapulo-humero-olecranien. )—The tri-
ceps muscle of the arm is situated on the poste-
rior surface of the humerus, and, as its name
implies, has its origin by three heads. The long
head arises by a short, flat, thick tendon from
a rough portion of the inferior costa of the
scapula, immediately below the glenoid cavity,
and passing downwards in front of the inser-
tion of the teres minor, and behind the teres
major it forms a large belly, which covers the
posterior surface of the os humeri. The se-
cond or short head arises from the outer and
back part of the os humeri, beginning by a
pointed origin immediately below the insertion
of the teres minor; it continues to arise from
the external ridge of the humerus as low down
as the external condyle; from the surface of
the bone behind this ridge, and from the back
art of the external intermuscular ligament,
e third head, which is the shortest, called

220 ARTERY.

brachieaus externus, arises by an acute point
from the internal ridge of the os humeri, be-
ginning immediately below the insertion of
the teres major; it also arises from the internal
ridge as far down as the internal condyle, from
the surface of the humerus behind this ridge,
and from the posterior surface of the internal in-
termuscular ligament. The three heads unite
above the middle of the os humeri, and cover the
whole of the back part of that bone; they form
a thick broad tendon, which is inserted into
the rough surface on the superior part of the
olecranon process of the ulna, adhering closely
to the ligamentous fibres covering the posterior
surface of the synovial membrane. of the
elbow-joint; the lowest fibres of the second
and third heads of this muscle, which arise
from the back of the condyles, run nearly
horizontally into the tendon.

The triceps is covered posteriorly by the
teres minor, deltoid, fascia of the arm and in-
teguments; in front it is in contact with the
posterior surface of the humerus, the inter-
muscular ligaments, and the back part of the
capsule of the elbow-joint. This muscle ex-
tends the elbow ; when the long head contracts,
it draws the scapula towards the humerus,
and, if the scapula be fixed, it draws the
humerus backwards.

For BIBLIOGRAPHY, see MUSCLE, and ANATOMY
(INTRODUCTION).
(J. Hart.)

ARTERY, (normal anatomy): HeTnea, a IFO
Tou Tov weea Tyee, ab aere servando. Fr. ar-
tere. Germ. Pulsader, Schlagader. Ital. arteria.
The arteries are the vessels which carry the
blood from the heart, and distribute that fluid
throughout the body. The trachea was ori-
ginally called artery from the circumstance of
its containing the air which it transmits to the
lungs. The term artery was exclusively ap-
plied to the trachea by Hippocrates and his
cotemporaries, by whom the vessels now called
arteries were described as pulsating veins.
Aristotle restricted the term artery to the tra-
chea, and described the aorta as the lesser
vein. We find these vessels called arteries
in the writings of Areteus, Pliny, and Hero-
philus, probably on account of the adoption of
the opinion of Erasistratus, who taught that they
contained a vapour or spirit. The vessels now
known as arteries, however, were more dis-
tinctly so designated by Galen, who affirmed
that they were full of blood, and described the
arteries and veins as forming each a tree, whose
roots implanted in the lungs, and whose
branches distributed through the body, were
united by a common trunk in the heart.

There are two great arterial trunks—the
aorta, which arises from the left ventricle of
the heart, and the pulmonary artery, which
arises from the right ventricle of that organ.
Each of these vessels has an origin, a trunk,
and branches, which divide and subdivide in
an arborescent form, until they are reduced in
size to the most delicate degree of minuteness,
terminating in the capillary vessels, which can
be traced entering into all structures except
cartilage, hairs, and epidermoid parts. Striking

as the contrast is between the size of the primi-
tive arterial trunks and that of the almost in-
visible capillary vessels, comparatively few
divisions intervene between the two extremes
of the arterial system, their number hardly
exceeding twenty, as Haller ascertained by
counting the divisions of the arteries of the
mesentery between the place of their origins

‘from the aorta, and their termination in the

capillaries of the intestines.*

That the arteries in general are circular
tubes is evident from an inspection of their
orifices when cut across, even in the dead
body. The walls of the larger arteries, when
empty, collapse, so as to present, on a trans-
verse section, an aperture more or less ellipti-
cal: when distended, however, either by the
blood during life, or by injection in the dead
body, these also are circular; so that the
circular form may be considered as universal
in all parts of the animal system except at the
origins of the aorta and pulmonary artery,
where the circumference of each of these ves-
sels is distended into three sacculated pouches
of equal size, called the lesser sinuses; and in
the ascending portion of the arch of the aorta,
which has a dilatation on its right side, in-
creasing with years, called the greater sinus.

The arteries in general become smaller in
their course in proportion to the number of
branches arising from them. To this, however,
there are exceptions, of which the aorta pre-
sents a remarkable example, being of as great
a capacity near the origins of the primitive iliac
arteries as it is in its thoracic portion, and the

‘vertebral arteries are as large where they enter

the foramen magnum of the occipital bone as
where they arise from the trunks of the sub-
clavians, notwithstanding that they have given
off many branches in the intermediate part of
their course.

Wherever an artery runs for some distance
without giving off branches, it appears to suffer
no perceptible diminution in its size, as has
been ascertained by the experiments referred to
by Baron Haller,t and repeated by Mr. Hunter,t
in which the common carotids were found as
capacious near the place of their division into
the external and internal carotids as at their
origins; and the same remark being considered
as equally applicable to all other arteries simi-
larly circumstanced, it has been stated in
general terms that the arteries and their branches
are cylindrical, and that the whole of the
arterial system is a series of cylindrical tubes.

Although the cylindrical form is pretty
general throughout the arterial system, it is by
no means accurately preserved. Several arteries
increase in size in the progress of their course ;
of this we have examples in the umbilical
arteries, which expand ~as they approach the
placenta, and the spermatic arteries, especially
in the bull and wild boar, which enlarge con-

siderably as they proceed to their destination. 4

Moreover, Haller§ and Martinus have shown

* Haller, Elementa Physiologie, t. i. sect. 1.§17.
+ Elementa Physiologia, t.i.s.1,§3.

+ Treatise on the Blood, &c., p. 168 et seq.
d4to edit. Lond. 1794. t
§ Elementa, t. i. s. 3, §3..

‘
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eS oe

>"
= Er

-

ARTERY.

by experiments, that in every instance where an
artery divides in the human body, it undergoes
a dilatation immediately before such division ;
and this fact derives confirmation from the
experiments of Mr. Hunter on the carotid arte-
ries: it is much more unusual for an artery to
diminish in size in its course unless it has
furnished branches. Santorini* states, how-
ever, that he observed the carotid artery of an
ostrich (Struthio camelus) to have become nar-
rower in a portion of its course of six inches in
length, for which space no branch had been
given off.

The arteries become smaller and more nu-
merous by repeated divisions: the combined
area of the branches of each artery, however,
exceeds the area of the trunk from which they
are given off, in every instance, in consequence
of which the capacity of the arterial system, as
a whole, is increased in proportion to the
number of its divisions. It is from this cir-
cumstance that the arteries have been said to
represent a cone, the apex of which is at the
heart, and the base in the capillaries.

_ When an artery divides into several branches
of unequal size, the largest usually continues
its course in the direction of the original trunk.

The branches of the arteries are for the most
part given off at acute angles; some few, as
the superior aortic intercostals, go off at obtuse
angles, and the lumbar arteries arise from the
aorta at right angles.

The arteries appear in general to take the
shortest course to the parts they supply ; hence

the tendency they have to run in straight lines.

In many situations the arteries are remark-
able for having a tortuous course, as is par-
ticularly evident in the arteries of the stomach,
intestines, bladder, uterus, lips, iris, &c., where
this disposition appears to be a provision to
obviate any interruption to the circulation
which might result from the great or sudden
changes of volume, form, or situation to which
those organs are subject in the performance of
their functions: in other instances the arteries
appear to be contorted for the purpose of
breaking the impulse of the systole of the ven-
tricle on the blood, and thereby moderating the
force with which that fluid is propelled into
vessels partaking of the delicacy of structure
of certain organs to which they are distributed,
as the arteries of the brain, spleen, testicle, &c.

The smaller arteries, running among loose
structures, are rendered tortuous during each
systole of the ventricle of the heart, a pheno-
menon which we have frequently witnessed
where such vessels were exposed for a few
inches of their course during surgical operations.

Anastomoses.—The several. parts of the arte-

tial System communicate freely with each other;

and these communications, known by the name
of anastomoses,+ are more frequent between the
arteries in proportion to the remoteness of these
vessels from the heart. Three kinds of anas-
tomosis have been distinguished by anatomists:
first, two vessels of nearly equal size approach
and join so as to form an arch in such a man-

* Observationes Anatom. c. 7. n. 6.
t From ava, per, croum, 03.

221

ner as to render it impossible to determine the
exact point of their union: this arch gives off
smaller vessels. Of this kind is the anasto-
mosis which takes place between the arteries of
the intestines and the arteries in the neigh-
bourhood of joints. Secondly, two arteries are
sometimes connected by a transverse branch,
as the two anterior cerebral in the arterial circle
at the base of the brain. We find this kind of
communication, also, between the two um-
bilical arteries as they approach the placenta.
Thirdly, two arteries join at an acute angle, so
as to form a single trunk: thus the two verte-
bral arteries form the basilar, the two anterior
arteries of the spinal cord unite in a single
trunk ; and in the foetus the ductus arteriosus
joins the thoracic aorta in a similar manner.
Besides these more obvious communications
between vessels of a larger size, the anastomoses
of the capillaries are so frequent as to give to
those vessels, when successfully injected, the
appearance of a fine net-work.

It is by means of the anastomoses that
the circulation is carried on in a limb after the
trunk of its chief artery has been obliterated
by disease, injury, or a surgical operation ; and
the well-known efficiency of the anastomosis of
arteries in re-establishing the circulation in
parts from which the direct supply of blood
through the principal artery has been cut off,
has led to the performance of some of the most
brilliant operations by which modern surgery
has been raised to the exalted rank it holds at
the present day.

The larger trunks of arteries are inclosed
within the cavities of the body, or run their
course on the sides of the limbs least exposed
to external injuries, being in general deeply
situated in the intervals between the muscles,
so as to be protected against wounds or other
external injuries, to which they are therefore
less exposed than if they had been more super-
ficially situated.

The arteries and their branches are every
where surrounded by a layer of cellular tissue,
called the arterial sheath, connected more or
less intimately with the neighbouring struc-
tures, but having so loose an attachment to the
arteries as to allow them to glide freely on its
inner surface in all their motions, by which
means they frequently escape being injured
when penetrating wounds traverse parts con-
tiguous to them ; and it is owing to the loose-
ness of the attachment of the arteries to their
sheath that they retract so remarkably within it
when cut across. The sheath is generally
strongest around the arteries most exposed to
external injury: thus it is particularly strong
where it surrounds the arteries of the limbs; it
is less distinct on the arteries within the thorax
and abdomen, many of which receive coverings
from the serous membranes; and it is so ex-
tremely delicate around the arteries of the
encephalon as to have its existence in this
situation questioned by some anatomists.

Structure of arteries.—The arteries are of a
pale buff colour when empty. The absolute
thickness of their parietes is greatest in the
larger trunks, but more considerable in pro-
portion to their calibre in the smaller branches.

222 ARTERY.

The parietes of arteries are divisible into three
tunics, known by the names of external, mid-
dle, and internal.

The external tunic, called the cellular coat,
(tunica cellulosa propria of Haller,) is of a
whitish colour, thin, dense, and firm: it is
formed of condensed cellular tissue, containing
fibres closely interwoven and crossing each
other at obtuse angles to the length of the
vessels. The structure of this tunic is loose
on its external surface, and connected by deli-
cate lamine with the arterial sheath : its internal
surface is very closely attached to the external
surface of the middle tunic.

The middle tunic of the arteries (the tunica
musculosa of Haller) is dense, firm, of a red-
dish yellow colour, and composed of fibres,
which, on a superficial view, seem to run
transversely: when this tunic is submitted to
a closer examination, we find that none of its
fibres are sufficiently long to form perfect rings
encircling the whole of the circumference of
the vessels; they are all short and straight,
with a slight degree of obliquity in their direc-
tion, and their extremities are lost among the
neighbouring fibres. The middle tunic may
be divided into several layers by the knife of
the anatomist, and these are found to increase
in density from the external to the internal
surface. There are no longitudinal fibres in
this structure.

As Haller has remarked, the middle tunic
of the arteries is not continuous with the mus-
cular substance of the heart. For the descrip-
tion of the manner in which the middle tunic
of the arteries is connected with the heart, and
of the fibrous structure interposed between
the muscular texture of that organ and the
middle tunic of the arteries, we refer to the
article Aorta. The continuity of the middle
tunic through all parts of the arterial system
is uninterrupted. Although the absolute thick-
ness of this tunic is greatest in the aorta and
larger trunks, its thickness in proportion to
the area of the vessels manifestly increases as
these diminish in size; wherever an artery is
curved, it is thicker on the convex than on the
concave side, and in all the angles formed by
the divisions of arteries its thickness is more
considerable than in other situations. The
colour of the middle tunic is yellower in the
larger trunks and more of a reddish tint in the
smaller branches. The middle tunic of the
arteries has a degree of firmness sufficient to
preserve the circular form of the artery even
in its empty state, and after the other tunics
have been removed. This tunic possesses a
slight degree of strength and elasticity in the
longitudinal direction; im the circular direc-
tion it exhibits both these properties in a more
marked degree. The strength and elasticity
of this tunic diminish progressively from the
larger to the smaller arteries. There is so
close a resemblance between the substance of
this tunic and the yellow elastic fibrous tissue
of the ligamenta subflava connecting the crura
of the vertebra, as well in its yellow colour
and the firmness of its fibres, as in its elastic
property, that many anatomists regard both these
structures as being nearly if not perfectly

identical. Mr. Hunter instituted a variety of
experiments to prove that this tunic possessed
a power of contraction similar to that of mus-
cular structure in addition to its elasticity ;
but, notwithstanding the results of the re-
searches of this great anatomist and physio-
logist, by which he showed, in the clearest
manner, that the arteries were endowed with
a power of contraction totally distinct from
their yee of elasticity, he never demon-
strated, in a positive and unequivocal manner,
the presence of muscular fibres in it, nor has
any other anatomist, who, since his time, may
have investigated the subject of the structure
of this tunic, been more successful in dis-
covering in it any decided trace of muscular
fibres. Beclard* considers it to be a pecu-
liar elastic tissue having an intermediate charac-
ter between muscular and ligamentous fibre.
From carefully examining this structure, it
appears to differ both from the yellow elastic
fibrous tissue and from the muscular tissue ;
possessed of the elasticity of the former, but
differing from it in being composed of fibres
of a softer consistence and more easily torn ;
from the latter it differs not only in the colour
and consistence of its fibres, but moreover in
the slow and gradual mode of its contraction
under the influence of mechanical or chemical

stimuli; unlike the muscular fibre, it retains its.

power of resistance as perfectly in the dead as
in the living body.

Bichatt asserted that there was a total ab-
sence of cellular tissue in the structure of the
middle tunic of arteries. Meckel, who ranks
higher as an authority for matters of fact in
anatomy, has admitted this assertion as if it
were an established fact: neither of these
authors, however, has advanced a single valid
argument or brought forward a well-founded
proof in support of the correctness of this
statement; wherefore we feel the less reluc-
tance in registering our dissent from such high
authorities on this point, which we found on the
consideration of the following circumstances :-—

First, there is no analogous instance of an
organized structure receiving bloodvessels and
nerves into which cellular tissue does not also
enter as a component part.

Secondly, we have the authority of the
accurate and learned Haller, in testimony of
the fact of the fibres of the middle tunic of
the arteries having cellular tissue interposed
between them, being, as he expresses himself,
“ cellulositate paucissima separate.” Beclard
entertains a similar opinion founded on the
circumstance that when a portion of an artery
is stripped of its external tunic, granulations
will shoot up from the exposed surface of the
middle tunic.

Thirdly, we have frequently observed that,
when a portion of an artery stripped of its
external tunic, is divided longitudinally and
macerated in water for several days, the mid-
dle tunic increases in thickness, and its fibres

become more distinct and are more easily ~
separated from each other; by continuing the —

* Anatomie Générale, p. 325.
+ Anatomie Générale, tom. iii.

a SS Oo ee ee lL ee

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ARTERY.

maceration, the intervals between the fibres
become greater, and as the putrefactive pro-
cess sets in and advances, the whole substance
of the middle tunic takes on the form of a
spongy mass, and ultimately the fibres cease
to be any longer discernible, having been re-
duced to the state of a soft pulp, while the
cellular structure is rendered more evident.
The following appears to us to be the rationale
of the phenomena above described: the in-
crease in thickness which the middle tunic at
first undergoes is owing to the cellular tissue
interposed between the fibres imbibing the
water in which it has been immersed, in virtue
of its hygrometric property; and the spongy
appearance observable after the maceration
has been continued for a length of time, is the
result of the cellular tissue having the property
of resisting decomposition by putrefaction
much longer than the fibrous tissue.

The internal tunic (intima of Haller) is the
thinnest of the three; it is continuous with
the lining membrane of the heart, in extending
from which into the arteries it forms a dupli-
cature, contributing to the composition of the
semilunar valves: in the larger arteries, when
empty, it sometimes forms longitudinal folds ;
in some arteries, such as the popliteal, and the
brachial at the bend of the elbow, it presents
transverse folds or wrinkles; it also forms
transverse wrinkles in arteries which have re-
tracted after amputation: its internal surface,
which is in contact with the blood in the living
body, is smooth, polished, and bedewed with
a fine exhalation; its external surface adheres
to the internal surface of the middle tunics in
the larger trunks of the arteries; this tunic
may be divided into two layers, the internal
of which is thin and transparent, while the
external is whitish and opaque, having its struc-
ture blended with that of the middle tunic;
it is the tunica cellulosa interior of Haller,
and is the seat of the calcareous, steatomatous,
and atheromatous deposits, which so frequently
occur as morbid appearances in the coats of
the arteries. We do not perceive fibres nor
any other signs Of organization in the inner
layer of this tunic in its healthy state; it is
almost completely inelastic and very brittle ;
it tears with equal facility in every direction ;
compared with other structures it bears the
closest resemblance to the arachnoid mem-
brane of the brain; the smooth and _ highly
polished condition of the free surface of this
tunic is an admirable provision, whereby the
effect of friction in diminishing the velocity
of the passage of the blood through the arte-
ries is reduced to the smallest possible amount.

The following mechanical contrivance ob-
servable in the interior of the arteries would
appear to be a provision for facilitating the
distribution of the blood through the divisions
of the arterialsystem. As the branches of the
arteries mostly arise from the trunks at acute
angles, the portion of the circumference of
their orifices on the side next the heart is
smooth and depressed, forming a sort of chan-
nel sloping gently from the trunk into the
branch, while the opposite side, or that more
remote from the heart, is bordered by a ridge

223

of a semilunar valve-like form, composed of @
duplicature of the lining membrane in which
there is included a portion of the middle
tunic ; the more acute the angle at which the
branch arises, the greater is the prominence of
this ridge; it is altogether absent where branches
arise at right angles, as in the case of the emul-
gent arteries, and where branches arise at ob-
tuse angles to the trunk, it is found at their
orifices on the side next the heart.

The aorta and pulmonary artery are each
provided with three valves at their origins from
the ventricles; these valves, called sigmoid or
semilunar from their semicircular form, are
attached by their inferior borders, which are
convex, to the margins of the semicircular
flaps or festoons, into which the edge of the
commencement of the middle tunic of the
artery is divided; the superior edges of each
of these valves, which are free and floating,
form two concave lines, separated by a
projection in the centre, in which is con-
tained a small cartilaginous body, called
tubercle, globulus Arantit or corpus sesa-
moideum. The portions of the walls of the
artery corresponding to the valves are dilated
in the form of pouches, more marked in the
aorta than in the pulmonary artery; these are
the sinuses of Valsalva. The semilunar valves
are composed of a duplicature of the lining
membrane of the artery, including within it a
thin but strong fibrous expansion, continuous
with the fibrous structure, which connects the
middle tunic of the artery with the tendinous
ring encircling the arterial opening of the ventri-
cle; the free border of each valve contains a small
fibrous cord, as described by Beclard, having
the globulus Arantii attached to it in its centre.

An increase or diminution in the number of
the sigmoid valves is of rare occurrence, more
frequently presented in the pulmonary artery
than in the aorta, and oftener consists in the
number of valves being increased to four than
diminished to two.*

The mechanism of these valves is such as to
prevent the blood flowing in a direction con-
trary to its regular course ; for when that fluid
is propelled towards the ventricle, they are
separated from the parietes of the artery, and
being distended by the column of blood pres-
sing against their superior surfaces, they are
laid across the area of the vessel, which they
completely fill up by their edges being thus
brought into perfect contact and the globuli
Arantii meeting in the centre. There are no
valves in the arteries in any other situation.

The arteries, like other organized struc-
tures, are furnished with proper nutritious
arteries and veins called vasa vasorum. The
aorta and pulmonary artery at their commence-
ment receive some branches from the coronary
vessels of the heart; in all other situations the
vasa vasorum are supplied by the neighbouring
bloodvessels ; the vasa vasorum are very eVi-
dent in the external tunic of the arteries, they
can be traced until they penetrate the sub-
stance of the middle tunic, but not farther ;

* Meckel, Handbuch der menschlichen Anato-
mie. Band, i.

224 ARTERY.

they are more numerous and larger in young
than in adult and old subjects.

Absorbents are not visible on the coats of
any arteries except the larger trunks; however,
the removal of coagula formed in the interior
of all arteries after the application of ligatures
may be regarded as proving the existence of
absorbents in every part of the arterial system.

The arteries are plentifully supplied with
nerves, of which the aortic system receives more
in proportion than the pulmonary artery, and
the smaller arteries more than the larger trunks.
The trunk of the aorta, the pulmonary artery,
and the arteries of the head, neck, thorax, ab-
domen, and those of the genital organs, receive
their supply from the nerves of organic life.
These form a very intricate plexus -on their
surface. The arteries of the extremities receive
their supply of nerves from those of animal
life in their neighbourhood. Two sets of nerves
have been described as being furnished to the
arteries; one set, consisting of softer nerves, of
a flattened form, are said to be lost in the cel-
lular or external tunic, nervi molles ; the other
set, more firm and round, penetrate the middle
tunic, in which they form a thin membraniform
expansion, containing distinct fibres. Meckel*
justly considers the internal nerves as subdivi-
sions of the larger flattened external branches.
No nerves have yet been discovered on the
umbilical arteries, and the arteries of the brain
are supposed to be without any. The nerves
of the arteries become less apparent in old age.

The. specific gravity of the arteries exceeds
that of distilled water in the proportion of
106 to 100. They are proportionally lighter
and less dense than the veins; while the veins
possess more power of resistance, and are not
so easily ruptured as the arteries.

Physical properties.—Of the physical pro-
perties of the arteries the most remarkable are
the firmness of their parietes, their power of
resistance, and their elasticity. It is owing
to the firmness, which principally resides in
their middle tunic; that they preserve their
circular form in the empty state.

Their power of resistance has been made the
subject of experiment by Wintringham,t and,
more recently, by Beclard,{ from which the
following results have been obtained.

Their power of resisting rupture is very great,
and is generally in proportion to their thickness,
being greater in the aorta than in the pulmonary
artery. As the arteries diminish in size, their
absolute resistance diminishes ; however, as their
relative thickness and softness increase, their
extensibility and relative resistance undergo a
proportionate augmentation. The resistance of
all arteries of equal volume is not the same:
for instance, that of the iliac artery is greater
than that of the carotid. It is in the external
tunic that the power of resistance in the longi-
tudinal direction resides; the resistance in the
circular direction is much greater, and is owing
to the middle and external tunics conjointly ;
the internal tunic has very little power of re-

= Op. cit. .

+t Experimental Inquiry on some parts of the
Animal Structure. Lond. 1740.

¢ Anatomie Générale, p. 373.

gility as the external is for its toughness and
great power of resistance ; hence it is, that when
a ligature is tightened on an artery, the two
former are divided, while the latter remains

unbroken, as proved by the experiments of -

Dr. Jones.*

The successful employment of torsion of the

arteries as a means of suppressing hemorrhage
is in like manner owing to the greater power of
resistance possessed by the external tunic as
compared with the other two. The process by
which arteries are obliterated by torsion is thus
explained by M. Amussat,+ to whom belongs the
merit of having been the first to propose and
practise it. The divided extremity of an artery
is seized between the blades of a forceps, and
drawn out beyond the surface of the wound :
the vessel is then taken hold of with a second
pair of forceps a few lines higher, and held
firmly while the operator commences to twist
the forceps with which he holds the extremity
of the vessel in the direction of its axis, making
from five to nine or ten turns, according to the
size of the vessel operated upon. On examin-
ing an artery which has undergone this process,
it will be found that the middle and internal

tunics of the twisted portion have been broken

in several places by the external tunic, which,
remaining unbroken, is formed by the twisting
process into a sort of spiral ligature, so tightly
applied round the inner tunics as to set at
defiance every attempt to unravel it by twisting
the vessel in the opposite direction.

The arteries are highly elastic; they admit of

considerable distension in the longitudinal di-
rection, and quickly contract to their original
length on the cessation of the distending force.
In the transverse direction they yield less, and
after distension resume their previous state with
greater force. When a fluid is injected with
some force into the arteries in the dead body,
they become distended and elongated ; and if,
when they are in this state, the force with
which the injection was propelled be removed,
they will contract to their previous state, or
nearly so, expelling a portion of the fluid which
had been thrown into them. During life the
arteries are in a state of elastic tension, so that,
when divided, their cut extremities retract with-
in their sheath.

The arteries are endowed with the power of
contracting in a gradual manner, which they
exhibit under the following circumstances ;:—
when the passage of the blood is stopped in the
principal artery of a limb, the vessel gradually
contracts, its cavity is reduced in size, and
ultimately becomes obliterated by degenerating

into a filamentous band of cellular tissue ; while
the collateral branches, taking up its function

of conveying blood to the distant parts, are
proportionally enlarged, rendered more tortuous,
and increased in length.

diminishes, and one or more vessels of in-
creased size become as it were promoted to

* Treatise on Hemorrhage. Lond. 1805,
+ Archives Générales de Médecine, t. xx. Aoit,

1829, p. 606.

sistance in either direction. The middle and —
internal tunics are as remarkable for their fra-

In process of time
the number of enlarged collateral branches

the station which the principal trunk had held
in the circulation while in its normal condition.
Several distinguished anatomists and physiolo-
gists have considered the property of elasticity
of the arteries sutlicient to account for all the
phenomena of the circulation of the blood
through these vessels. ‘This opinion has been
} principally insisted on by Haller, Bichat,Nysten,
. and, at the present day, by Magendie; elasticity,
however, can only account for contractions
_ taking place in consequence of previous dis-
tension, and is equally evident after death as
during life: but observation and experiments
have shewn that, in the living body, the arteries
possess an additional power of contraction, by
which their calibre may be diminished in various
‘degrees; in some instances even almost to
obliteration. And this power of contraction
has been considered by many anatomists to
indicate the existence of a property of irritability
in the arteries, similar to, if not identical with
muscularity. The existence of irritability in
the arteries was denied by Haller in conse-
quence of his not having succeeded in render-
ing it evident by the application of chemical or
mechanical stimuli. Bichat, Nysten, and Ma-
gendie, embraced a similar opinion, on the
strength of the following facts :—mechanical or
chemical stimuli, even the galvanic fluid, ap-
plied to the surfaces of the arteries, produce no
motions; when the fibres of the middle tunic
are dissected off in successive layers in living
animals, they are not observed to display that
‘quivering motion visible among the fibres of
muscles similarly treated. When cut longi-
tudinally, the inner surface of the arteries does
not become everted like that of canals, such as
the intestines, which have a decidedly muscular
_ tunic: they do not contract when separated
_ from the heart. The finger introduced into a
__ living artery is not constricted; stimuli applied
to the nerves of particular arteries, or to the
nervous system generally, do not produce con-
tractions ; strong acids applied to arteries pro-
- duce a corrugation or crisping of their struc-
| ture, not a contraction, like that of muscular
_ Structure.
The contrary opinion as to the existence of
_ irritability in the arteries has been maintained
__ by some of the most distinguished and accurate
_ anatomists and physiologists, among whom are
Hunter, Semmerring, and Verschuir. It may be
stated in a general manner, as an objection to
the arguments of Bichat, founded on the circum-
Stance of the arteries not having contracted
_ when stimuli were applied to them in some
_ €xperiments which he performed, that other
irritable parts, even the muscles themselves, do
not at all times contract on the application of
_ stimuli. In fact, most of the experiments de-
tailed by Bichat, as proving the absence of
irritability in arteries, have been performed by

Hunter, Verschuir, and Hastings, and with
results directly contrary to those obtained by
_ that very distinguished anatomist. Verschuir*

_ found that the arteries contracted when stimu-

il
,

___* Dissertatio de arteriarum et venarum vi irrita~
bili. Gronigen 1766.
pik VOL. 1.

ARTERY.

225

lated by the mineral acids, by electricity, and
the application of the point of a scalpel. Dr.
Thomson* also saw them contract on the ap-
plication of ammonia, and when punctured
with the point of a fine needle in the living
body. Irritating the nerves by the galvanic
fluid or by, caustic alkalies has been fol-
lowed by contraction of the arteries Mr.
Hunter} found that the exposure of arteries to
the air was followed by their contraction to
such an extent as to produce their obliteration.
An instance of this we have twice witnessed
in the brachial artery when exposed during the
progress of an operation for traumatic aneurism
at the bend of the elbow. The contraction
of divided arteries is well known to be an
efficient means of arresting hemorrhage, in op-
position to the force with which the blood
is propelled through them by the heart’s
action. iy

In conclusion, we may observe that the
arteries are proved to be both elastic and
irritable; that elasticity predominates in thie
large trunks, and irritability in the smaller
branches ; that their irritability, like that of
muscles, is under the influence of the nervous
system, and obeys the immediate application
of chemical and mechanical stimuli, the effects
of which must, however, be very much modified
by the influence of the elasticity with which
they are endowed. (See Crrcuxation.)

In men the arteries are said to have their
tunics thicker, and to possess greater density
and a higher specific gravity than in women.
The arteries are larger, more numerous, and
their coats are softer in young persons: they
become more fragile, and their elasticity di-
minishes, in advanced life.

In the progressive development of parts the
arteries appear before the heart; but in the
chick, during its evolution, the veins of the yolk
precede them in their development, as ascer-
tained by the researches of Malpighi,§ Haller,||
Wolff, Pander,** and Rolando.tt+

BIBLLOGRAPHY. — Hebenstreit, Progr. de arte-
riarum corp. human. confiniis, 4to. Lips. 1739
(Ree. in Haller’s Coll. Disp. Anat. vol. ii.) ; Ejus,
Progr. de vaginis vasorum, 4to. Lips. 1740 (Rec. in
Haller, &c. vol. ii.); Ejus, Progr. de flexu arteri-
arum, 4to. Lips. 1741 (Rec. in Haller, &c. vol. ii.)
Monro, on the coats of arteries and their diseases, in
Ej. Works, 4to. Edinb. De la Sone, Sur la structure
des artéres in Mém. de Paris, 1756 and 1762.
Van Swieten, De arterie fabrica et efficacia incorp.
human. 4to. Lugd. Bat. 1725. Albinus, De arterize
membranis et vasis in Ej, annotat. academic, lib. iv.

* Lectures on Inflammation.
p. 75-89.

+ Vide a paper by Sir E. Home on the Influence
of the nerves upon the action of arteries, Philoso-
phical Transactions for 1814. —

¢ Treatise on the Blood, p. 114.

| De formatione pulli in ovo.

Edinburgh, 1813.

Opera Minora, t. ii.
Theoria Generationis.

** Journal de Progrés des Sciences et des In-
stitut. Médicales, t. v. and Journal de Physique,
t. Ixviii. also his Beitriige zur Entwickelungsges-
chichte des Hiinchens im Eie. ‘Wiirtzburg, 1817.

++ Journal Complémentaire du Dict. des Sc.
Méd., t. xi. p. 323, et t. xii. p. 34.

Q

226

Haller, De arteriarum et venarum fabrica in Ej.
Op. minor. vol. i. Hunter, on the blood, &c. 4to.
Lond. 1794. Letierce, Essai, &c. sur la membrane
interne des artéres, Thes. de Paris, 1829, and in
Archiv. Gen. de Méd. Nov. 1829. Haller resp.
Berklemann, De nervorum in arterias imperio, 4to.
Gotting. 1744, and in Halleri Op. Min. t.i.
Wrisberg, De nervis arterias venasque comitantibus,
in Ej. Comment. vol. i. 8vo. Gotting. 1800. Luce,
Obs. Anat. circa nervos arterias adeuntes et comi-
tantes, 4to. Frft. a M. 1810, Germ. in Reil’s
Archiv. Bd. ix. Ribes, in Mém. de la Soc. Méd,
d’Emulation, t. viii. 1817, and in Meckel’s Archiv.
Bd. v. Verschuir, De Arteriarum et Ven. vi irri-
tabili, &c. 4to. Groning. 1786. Parry, of the pulse,
&c. 8vo. Lond. 1816; Ej. Additional experiments
on the arteries, 8vo. Lond. 1819. Jaeger, De ar-
teriarum pulsu, 8vo. Viceb. 1820. Hastings, De
vi contractili vasorum, 8vo. Edinb. 1818; Ejus,
on inflammation of the mucous membrane of the
lungs, and inquiry respecting the contractile power
of the bloodvessels, &c. 8vo. Lond. 1820. Meckel,
Verlauf der Arterien und Venen, in EHjus Archiv.
B. i. 285 and 450. Ehrmann, Structure des ar-
teres, &c. 4to. Strasb. 1822. Belmas, Structure
des arteres, &c. 4to. Strasb. 1822. Oppenheim,
Experimenta circa vitam arteriarum, 4to. Mannh.
1822. Wreden, Arteriologische Tabellen. fol.
Hannov. 1721. Chirol, Tab. de toutes les artéres
du corps humain, fol. Paris. Murray, Descriptio
. arteriarum corp. human. in tab. redacta Diss. i.-iv.
Ato. Upsal, 1780-83; 8vo. Lips. 1794; Anglice a
A. Scott, 8vo. Edinb. 1801. Barclay, Description
of the arteries of the human body, 12ma. Edinb.
1812. Harrison, Surg. anat. of the arteries of the
human body, 2 vol. 12mo. Dubl. 1824-25. Der-
mott, Locality and distribution of the arteries,
12mo. Lond. 1827; Kj. THustr. of the arteries, fol.
Lond. 1825. Haller, Icones anatomice, fasc. i.-
vii. fol. Gotting. 1743-56. Bell, Engravings of
the arteries, 8vo. Lond. 1811, 1824. Manec,
Traité de la ligature des arteres, fol. Par. 1832,
Tiedemann, Tab. Arteriarum corp. humani, fol.
Caroliruhe, 1822. Froriep, Chirurg. Anat. der
Ligaturstellen am mensch. Korper, fol.. Weimar,
1830. Richerand, Moyens de determiner exacte-
ment la situat. et le trajet des arteres: Societ.
Philomat An 13. Blizard, Lect. on the situation
of the large bloodvessels, 8vo. Lond. 1798. * * * *
The comparative anatomy of the arteries generally
is treated of in the Introd. of Blumenbach, the
Legons of Cuvier, the systems of Carus, Mechel,
Ucelli, Grant, &c. Particular subjects are dis-
cussed by the following writers :—Cazrlisle, Pecu-
liarity in the distribution of the arteries sent to
the limbs of slow-moving animals, in Phil. Trans,
1800. Rapp, Ueber das Wundernetz, in Meckel’s
Archiv. 1827. Barkow, Eigenthimlichkeiten
im Verlaufe der Schlagadern der Fischotter, in
Meck. Archiv. 1829, and in Ej. Disquisit. circa
orig. et decurs. Arteriarum, 4to. Lips. 1829. Bauer,
Nonnul. Avium systema arteriosum, 4to. Berol.
1825. Nitsch, De avium arteria carotide communi,
Hale, 1829. Barkow, Schlagadersystem der Vogel,
in Meck. Archiv, Jahr 1829. Meckel, in Ej. Ar-
chiv, Jahr 1826. Schlemm, Blutgefasssystem der
Schlangen, in Tiedem. u. Treviran. Zeitschr. f.
Physiologie, 2ter Bd. Tiedemann, Anat. der
Fischherzens, 4to. Landshut. 1809. Rathke, Herz-
kammer der Fische, in Meck. Arch. 1826. Cuvier
Valenciennes, Hist. nat. des Poissons, t. i. Paris,
1828. Owen, on the Nautilus Pompilius, 4to. Lond.

1832.
(J. Hart.)

ARTERY, PATHOLOGICAL CONDI-
TIONS OF.—Notwithstanding the brilliant
success that has attended the labours of British
surgeons in the department of their profession
having reference to the arteries,a success that has
deprived hemorrhage of its terrors,and aneurism

ARTERY, PATHOLOGICAL CONDITIONS OF.

of half its danger, the pathology of the arterial sys-
tem is still far from being perfectly understood.
Doubtless, the appearances of disease in its more
advanced and destructive forms have been ac-
curately described as they have been carefull
observed, but that invaluable information which
enables a practitioner to detect its early and
silent approach, to trace its progress by con-
necting each symptom with the morbid change
that is going forward, and to predict with accu-
racy the time and the manner of its termination,
is as yet but very imperfect. Many cireum-
stances have unavoidably contributed to this.
It is quite possible that arteries may be in an
unhealthy condition without presenting any in-
dication of disease during life, which is, therefore,
in the subsequent examination overlooked. Itis
more than questionable whether arteritis occa-
sions pain, for it has been observed in situations
in which the patient never complained, and as
persons do not die from inflammation of the
arteries, the intensity of the disease has time to
subside, and its effects only remain for obser-
vation in alterations in the coats of the vessels,
or in an aneurism. Many able and intelligent
practitioners who have met with aneurisms
without number, have yet not seen an example
of acute arteritis, and are disposed to consider
the red colour of the internal membrane of the
vessel observed in cases presumed to be so by
others as a staining by the blood after death.
These facts prove the imperfection of our know-
ledge of the pathology of the arterial system ;
and years of patient investigation must still
be passed both by the bed-side and in the
dissecting-room before the dreams of hypo-
thesis give place to the certainty of scientific
demonstration.

In prosecuting this inquiry, that source of
information so valuable in the elucidation of
other subjects in physiology, the experimenting
on animais, is wholly closed; the artery of the
animal bearing no analogy whatever to that of
man, either in susceptibility of disease or in the
powers of reparation after injury. It appears,
from Dr. Jones’s* experiments, that the artery
of a dog, if wounded only to a moderate ex-
tent, is capable of re-uniting and of healing so
completely that after a certain time the cicatri-
zation cannot be discovered, either on its inter-
nal or external surface ; whilst it is nearly certain
that in man the wound of an artery can only
be healed by the complete obliteration of the
vessel at the spot where it has been injured.
It is difficult if not impossible to bleed an —
animal to death by opening a moderately sized —
artery, whilst few surgeons would be willing to
entrust a wound of a branch of the temporal in
man to the resources of naturealone. The facts,
too, that aneurism is a disease unknown among
inferior animals,—that it cannot, by any inge=—
nuity of contrivance, be artificially produced, and
that the earthy depositions so commonly met
with in the arteries of aged persons are peculiat
to the human species, would tend to shew tha
some difference of structure existed, some pé
culiarity favourable to the production of

~~ TS

* Jones on Hemorrhage, pp. 107 to 111 inel.

5 tee

ARTERY, PATHOLOGICAL CONDITIONS OF.

ease in the artery of the latter. Indeed, in
examining and comparing the artery of a sheep
or a dog with that of man, some very obvious
differences are apparent: the former is firmer
if not actually thicker in its coats ; it maintains
its circular form more completely, and seems to
possess the quality of elasticity in a greater
degree of perfection. These circumstances,
however, are insufficient to account for that
comparative freedom from disease ; and pro-
bably the greater susceptibility of man may be
traced to the indulgence of certain habits and
propensities from which the animal is debarred,
and which, in many other instances as well as
in this, seem to be the predisposing causes
of disease in the human race.

The surgical pathology of the arteries presents
itself in two different though equally interesting
points of view, one having reference to the
effects ofa wound or other injury to a healthy
vessel, embracing a consideration of the pro-
cess by which such injury is remedied or re-
paired by the efforts of nature alone or by the
assistance of art, and the circumstances that
influence its success or failure ; the other refer-
ring to the appearances and consequences of
disease, either as it commences idiopathically
within the vessel itself, or is propagated from
adjacent parts or structures to it. A lesion
of the structure of an artery is of but slight
importance provided its function is unimpaired,
that is, as long as the blood it was destined to
circulate passes through it or is conveyed by
some other channel in the natural course of the
circulation : even the aorta has been obliterated
without any serious inconvenience to the indi-
vidual in whom it occurred. But when the
lesion is of such a nature as to interfere with
this function, when the blood is allowed to
escape either externally as from an open wound,
or internally as in the different species of aneu-
tism, results of a most formidable nature
ensue, greatly modified, however, in their cha-
racter and consequences by a number of cir-
cumstances highly deserving of attention.

Wounds and injuries of arteries. — It
cannot have escaped observation that the
nature of the wound or rather of the substance
that occasioned it exerts a striking influence
on the phenomena both of hemorrhage and of
the process by which it is restrained. Lacerated
wounds seldom bleed, although the torn artery
may be left hanging out an inch or more be-
yond the adjacent surface. Gun-shot wounds,
also, if the artery is completely divided, are
not often followed by hemorrhage, although
Some instances to the contrary occasionally
happen; but if the vessel is only notched or

ally cut, the bleeding is as profuse as from

_ any other cause. Ifan artery is wounded by a
_ Cuttimg instrument or by puncture, however, the

is poured out most freely; yet even here

_ there are varieties, according to the size and

importance of the vessel, the extent and direc-
tion of the accompanying wound, and the cir-

progress of the case will exhibit con-
variety, and demonstrate the fallacious

227

views of those who, grounding their opinions on
experiment, would limit the process of recovery
to one operation, and regard the efforts of
nature as alike in all, whereas, as has been
remarked by Mr. Guthrie, this process essen-
tially depends on the size and variation of
structure of the artery; it is not the same in
large as in small arteries; and it is not even
quite the same in the upper and lower ends of
the same artery.

When a limb has been torn off by a cannon-
shot, by the fall of a tree on it, or by any simi-
lar violence, the arteries do not bleed: very
frequently the main trunk is seen hanging an
inch or more from the wound, pulsating, or at
least receiving an impulse from the sound
portion of the vessel, though (as far as I have
observed) not containing blood within it. It
hangs white, bloodless, and flaccid in the
wound, not very unlike a piece of narrow
wetted tape, and is smaller at its extremity
than at any other part. This narrow point,
which, according to Mr. Guthrie, is formed by
the contraction of the artery, is also in his
opinion the only barrier to the escape of the
blood ; for in a case of this description he cut
off the end of the artery at less than an eighth
of an inch from the extremity, when it bled
with the usual vigour. The extraordinary op-
portunities this gentleman has enjoyed, and
the accuracy of observation which his writings
evince, entitle his opinions to be received with
great deference, although ina physiological point
of view it is difficult to conceive how an artery
subjected to such a lacerating force should not
have its vital properties so much impaired as
to prevent its contracting at all, more par-
ticularly at the spot where it was torn across,
and where, therefore, the greatest injury was
sustained. At the same time there is no other
mode of explaining the case. All that portion
of the artery that is pendulous from the wound
appears to be smaller in diameter than in its
healthy state; there is cellular tissue at its torn
extremity, but it is not injected with blood,
and the coagulum, if any, within the vessel, is
so small as to be incapable by its mechanical
resistance of preventing the escape of the blood.
As there are scarcely any two accidents at-
tended by exactly the same degree of injury,
it is probable that nature in such cases possesses
different resources. In one case where the leg
had been torn off by the falling of a tree, and
left attached merely by a portion of the skin
over the gastrocnemius muscle, the posterior
tibial artery hung nearly three inches from the
wound. As the man had been carried a dis-
tance of eleven miles, and seemed much ex-
hausted, it was not deemed right to attempt
more at the moment than merely to relieve him
of the annoyance of the pendulous portion of
the limb by cutting through the skin. This
was performed incautiously, for no inconve-
nience was apprehended ; about an inch of the
extremity of the artery was removed, and it
bled just asin Mr. Guthrie’s case. In another
instance where the arm was shattered by a
steam-engine with such violence that some of

the muscles torn from their attachments re-
az

228

mained upon the wheel, the artery, divided in
the subsequent amputation more than two
inches above the wound, did not pour out one
drop of blood. In others, still, the cellular
sheath of the artery has been seen injected
with blood in a state of coagulation, the pres-
sure of which on its orifice seemed to be
sufficient to prevent bleeding.

Weare told that the observation made by
Amussat,* that in gun-shot wounds where all
the parts were lacerated, the extremities of
even the larger vessels did not bleed, suggested
to him the application of the phenomenon
to practical surgery, and led to the practice
of the torsion of arteries. This operation con-
sists in laying bare a portion of the divided
artery, and carefully detaching it from the sur-
rounding cellular membrane until its own cel-
lular tunic is distinctly to be seen; it is then
seized with a forceps, not unlike the common
artery-forceps of Bell, and twisted on its axis
until the extremity engaged between the blades
is completely detached by the torsion. This
forms something like a knot or knuckle at the
end of the vessel, which mechanically blocks
it up; a coagulum is formed within, and the
remainder of the process is said nearly to re-
semble that which succeeds the application of
a ligature. Not having practised torsion on
a vessel of any considerable size in the human
subject, nor had an opportunity of examining
after death a case thus treated, I am unable to
comprehend, with sufficient precision, the exact
process that is established. In experimenting
on the femoral arteries of dogs, I have always
found that the immediate obstacle to the flow
of blood was a coagulum situated at the orifice,
and apparently entangled in the lacerated cel-
lular coat; but for the reasons already men-
tioned, little confidence can be placed in such
investigations.

Hitherto we have been considering those
wounds of arteries, which, however important
in other respects, are not attended by hemor-
rhage, and although ignorant of the operations of
nature in effecting this result, it is of the less con-
sequence, inasmuch as it is not likely we shall
attempt to imitate them, or entrust a large-
sized vessel to torsion alone. The wounds of
arteries, accompanied by loss of blood, present
themselves under very different circumstances ;
there is always anxiety, agitation, and dismay on
the part of the sufferer, and it may be that
promptness and decision in the practitioner
shall be required to preserve life. In any of
these awful situations, coolness and self-pos-
session can alone ensure a freedom from em-
barrassment, and these qualities cannot be ex-
pected in any individual who has neglected to
' make himself acquainted with the nature of
the mischief that has occurred, and the means
‘by which it may be remedied.

The phenomena attendant on arterial he-
morrhage occasioned by incised and punctured
wounds exhibit remarkable varieties, according
to the size, and of course to the structure of
the vessel; to the circumstance of its having

* Dictionaire de Chirurgie de Rust, tom. ii.

—

ARTERY, PATILOLOGICAL CONDITIONS OF.

been fairly divided, or only notched, or punc-
tured; to the wound being so large and patu-
lous as freely to permit the escape of all the
blood externally, or so small or oblique that
the fluid, though withdrawn from the circula-
tion, is still retained within the limb. There is
still another condition of wounded artery in ~
which the blood that escapes from it is poured
into an adjacent vein, and continues to circulate,
though not in its proper vessel. However,
these latter cases are usually considered and
described as forms of aneurism, and will,
therefore, not be noticed until there is an op-
portunity of comparing the different species of
that disease one with another.

When a large artery is divided in an open
wound, it may happen that the patient dies
almost instantaneously, not from the absolute
quantity of blood lost, but from its being with-
drawn too suddenly from the circulation, just
as syncope is often produced by the rapid
abstraction of blood in the common operation
of phlebotomy. However, this is not uniformly
the case, and experience has proved that vessels
of such size and importance as the carotid and
femoral arteries may be divided, and yet suffi-_
cient time allowed for the successful interposi-
tion of art. Mr. Guthrie states, that when the
femoral artery is cut across in the upper part of
the thigh, the patient does not always bleed
to death, although frequently lost; while if the
division takes place in the middle or lower half
of the thigh, the bleeding will probably cease
of itself. When, however, an artery of still
smaller size is divided, the powers of nature
are almost always competent to restrain the
hemorrhage, and consequently it is from an
examination of vessels of this class under such
circumstances that a knowledge can be ob-
tained of the nature and extent of these
powers.

When a vessel of moderate size is divided,
the blood is poured forth in jerks from its
open mouth in a large and full stream; soon,
however, this stream is seen to become dimi-
nished in size, and most probably it ceases to
flow per saltum. If the patient faints, the
bleeding perhaps ceases altogether, nor will it
be renewed unless accident or indiscretion gives
to the blood an impetus sufficient to overcome
the obstacle that opposes its exit, whatever that
may be. When the artery is divided, its middle
coat retracts immediately that its natural state
of tension is removed, withdrawing with it the
lining membrane, but leaving the cellular, to
which it is but loosely attached, hanging out —
beyond it. It contracts, too, in diameter, as is —
evidenced by the diminished stream of blood. —
The power by which this contraction and re- —
traction are performed is a vital property inhe-—
rent in the artery itself; it has been called
muscularity, and endless arguments have thus
been raised about a name, as if no tissue in the
body but muscle could be capable of contrac-
tion. But it operates in a manner very differen
from the rapid and decided contraction of mus
it is slow, gradual, and continued, and, »
fore, is longer in bringing the large vessel
a state favourable for the suppression of he’

Hy
‘CA

ARTERY, PATHOLOGICAL CONDITIONS OF.

rhage than the small one. The next step is
the entanglement of blood in the cellular coat
of the vessel and its consequent coagulation
when it comes to press in the most advantageous
direction on its open mouth, and the hemor-
rhage is stopped.

Thus the immediate agent of nature, in the
suppression of hemorrhage, is pressure effected
by the clot of blood, whilst the vessel is placed
by its own properties in the condition most fa-
vorable to the operation ; and it is curious to ob-
serve how universally the principle has been
acted on, though probably first suggested by
accident.er empiricism. The burning iron of
the older surgeons produced the pressure of an
eschar ; agaric and sponge entangled the blood
and retained a coagulum on the spot; even the
more modern invention of the ligature is in the
first instance only pressure, but with the mani-
fest advantages of being applied directly and
immediately, of being firm and not likely to slip,
and independent of rest, position, and bandage,
which are indispensable when other modes of
compression are had recourse to.

But the permanent suppression of arterial
hemorrhage can only be effected by the actual
obliteration of the vessel at the spot where it
had been opened or divided, a process that is
the result of inflammation of the lining mem-
brane, and of the coagulating lymph thereby
nig out, or of the artery ceasing to transmit

lood through it, and thus becoming as it were
useless in the economy. Both these influences
are exemplified in the permanent cure of a
wounded artery, for in an incredibly short space
of time after the external coagulum has been
formed, lymph is effused from the wound in
the vessel : and internally, between this lymph
and the nearest collateral branch, another coa-
gulum of blood is formed, to which a consi-
derable degree of importance has been attached,
though probably without sufficient reason. It
cannot be very instrumental in controlling he-
morrhage, because it does not occupy the entire
capacity of the artery: its shape is conical, the
base lying on the lymph poured out from the
wound, from which it gradually tapers to the
next branch, and it seems to be formed of a small
quantity of the blood, which, being pushed into
that branch, remains there, is placed out of the
current of the circulation, and must coagulate.
The transmission of blood to the limb below
is now to be effected through the medium of the
anastomosing vessels, which for this purpose
become proportionably enlarged. This quality
possessed by arteries of increasing their own
diameters, or in other words of accommodating
themselves to their contents, is curious and
interesting, and although not admitting of ex-
etc, cannot for a moment be doubted.

0 fact has been more satisfactori!y proved by

e. dissection, and like the contractility of the artery

already noticed, the effects of this power exhibit
themselves gradually and slowly. The circu-
lation of the limb seems scarcely to be inter-
_ rupted, for in a few minutes the arteries below
; pan as has been observed by Dupuytren,
_ like soft cords under the finger, evidently filled
_ with blood, but totally devoid of pulsation. It

229

is a long time before this latter proof of a re-
stored activity in the circulation comes to be
perceptible, and perhaps is never again equal
to what it had been before the occurrence of
the accident. The external wound, of course,
heals like any other of a similar nature, and it
is rare that the limb experiences any incon-
venience subsequently. The internal coagulum
is soon absorbed, and in process of time the
vessel, from the point of division to the next
branch above and below, degenerates into an
sy Sak aang ligamentous cord.

uch is the progress of events when the
efforts of Nature are sufficient to arrest the
bleeding; but after all it is a fortunate case
that ends thus, and experience teaches that
there is little wisdom in leaving a moderately
sized artery to her resources alone. What more
frequently happens is this: the artery retracts
and contracts it is true, and a coagulum forms,
which, as the patient becomes faint or weak, is
allowed to become consolidated, and for that
time is sufficient to save him. But he recovers,
or perhaps he uses some stimulus or some ex-
citement, and the renewed circulation gradually
loosens the clot, and a fresh gush of blood takes
place. This recurs frequently, and an hemor-
thagic disposition is formed; the patient be-
comes pale and exsanguineous, anxious, and in
continual agitation, and without the interven-
tion of art has but a slender chance of sur-
viving. In these cases, art adopts the principle
of the natural cure, only regulating its force,
and ensuring its continued operation for the
requisite period. The first object to be at-
tained is the application of a- sufficient degree
of pressure to control the bleeding: the second
to maintain that pressure for a length of time
to ensure the obliteration of the vessel. This
is not the place to discuss the various methods
that have been adopted for the accomplishment
of these ends ; suffice it that the superiority of
the ligature has been so far. proved by expe-
rience, that few surgeons of the present day
would feel satisfied in entrusting a large or im-
portant vessel to a less powerful or enduring
compression. But the ligature is in itself not
unfrequently a cause of great and frightful mis-
chief, and, therefore, it will be necessary to
examine into all the circumstances connected
with this part of the subject.

In practice, a ligature is applied around an
artery under two different circumstances; one,
in the case of the wounded and bleeding artery,
it is placed on the open orifice of the vessel ;
the other, in the treatment of aneurism, the
artery is taken up and tied at a part where it
is supposed to be sound and uninjured. When,
in either of these cases, an artery is tied, the
first effect is obviously to bring its opposite
sides into apposition, and to arrest the flow of
blood through it. At the same time that the
internal and tibrous coats being shorter and less
tough yield under its pressure and are divided
completely, leaving the cellular coat entire,
still sustaining the ligature in its place. The
consequences of this division of the internal
coats are very similar to those already explained }
as following the complete section of the artery ;

230

there is the same effusion of lymph, the for-
mation of internal coagulum of the same conical
shape and to the same extent, the diversion of
the circulation through the collateral branches,
and if the case proceeds favorably, the ultimate
obliteration of the tube between the place
occupied by the ligature and the next anasto-
mosing branch. But the ligature is still to be
attended to. The portion of the cellular coat
included within its noose sloughs and dies,
and is to be detached from the remainder
by the absorption of the adjacent sound part.
This process takes place at different periods of
time according to the size of the vessel; it
separates from the subclavian about the twenty-
second day after the operation, from the femoral
about the sixteenth, and from the brachial so
early as the twelfth or fourteenth. Unfor-
tunately matters do not always proceed thus
favorably, and the separation of the ligature is
the commencement of a series of evils to the
patient and of embarrassment to the surgeon,
that can scarcely be paralleled in the practice
of surgery. It has been found, however, by
experience, that a ligature placed on an artery
that has been fairly divided, is move rarely
followed by those ill consequences that fre-
quently ensue when its continuous tube is tied,
and as this latter operation is so intimately
connected with the subject of aneurism, and as
it will be necessary to become acquainted with
the phenomena of inflammation in these struc-
tures, in order to understand those of secon-
dary or consecutive hemorrhage, this part of
the subject cannot at present be so favorably
discussed.

Morbid states of arteries. Aneurism.—
Aneurism (avevgicpos, vel avevevopos,) is a
term of such extensive application as to pre-
clude the possibility of an accurate definition.
It has been employed by Corvisart and others
to designate certain affections of the heart, but
is now most generally used to express a disease
produced by a dilatation of an artery, or by
solution of continuity“in one or all of its coats.
It is also applied to any distended condition of a
part of the vascular system, such as occurs when
an unnatural communication is formed between
an artery and vein, constituting the diseases of
aneurismal varix and varicose aneurism. The
name of aneurism by anastomosis has also
been given to those bloody tumours, which, at
first appearing only as marks or stains occa-
sioned by a congeries of vessels, increase either
with the growth of the individual, or according
as the vascular system may be accidentally ex-
cited, until finally they produce results of a
most formidable description.

_ Aneurisms have been classed, first, as to the
condition of the coats of the artery, a dilata-
tion of them being considered as the true aneu-
rism, whilst a rupture or ulceration of them
constitutes the false: and, secondly, as to the
condition of the effused blood, which, if it is
contained within a sac or bag, constitutes the
circumscribed \form of the disease, or if it has
been poured out throughout the circumjacent
cellular tissue, forms the diffused aneurism.
The nature of aneurism, however, will be better

ARTERY, PATHOLOGICAL CONDITIONS OF.

understood by considering it to consist of such
a lesion of an artery as will permit the B pen
of a portion of the blood out of the usual course
of the circulation, though not out of the vicinity
of the injured or diseased vessel, and according
to the different circumstances under which this
can occur, the disease will be found to arrange
itself under the following distinct species. In
the first four of these the effused blood is either
partially or entirely withdrawn from the circu-
lation, and becomes coagulated in its new
situation : in the others it passes from the usual
course of the circulation, but is not withdrawn
entirely from it, and consequently does not
coagulate.

1. Where by rupture or ulceration of the
internal and middle coats of the vessel, the
blood is propelled against the external cellular
coat, which becomes thus distended into a pouch
containing within it the extravasated blood, in
a more or less perfect state of coagulation,
which pouch is termed the aneurismal sac.
This is circumscribed false aneurism.

2. The true aneurism is when all the coats
of an artery, in one particular part of its cir-
cumference, are so far deprived of their elastic
properties as to yield, become distended, and
form a pouch, in which the contained blood is
similarly circumstanced.

3. It is not difficult to conceive that the sac
of a true aneurism, as just described, will not
long endure its state of unnatural distension
before its internal and fibrous coats either ulce-
rate or rupture, and then an aneurismal sac is
formed, consisting in one part of all the coats
of the dilated vessel, and in the other of the
cellular tunic alone. This is obviously a mixed
form of aneurism.

4. When there is a wound, rupture, or
ulceration of all the coats of an artery, in such
wise as to permit the escape of the blood into
the adjacent cellular tissue, a diffused aneurism
is formed. This, for reasons that need not
explanation, will be most frequently observed
to succeed to wounds or punctures of vessels,
but it may also be the consequence of an acci-
dental rupture of the sac of a circumscribed
aneurism allowing the blood to pass through
it, and spread itself (as it generally does) in
every direction throughout the loose cellular
tissue of the entire limb.

5. A direct and immediate communication
may be established between an artery and a
vein lying close upon it, as by the passage of a
lancet transfixing one vessel and entering the
other. This is the aneurismal varix, obviously
occurring with greater frequency as the result
of a wound, but nevertheless occasionally seen
as the product of disease. __

6. A small circumscribed aneurismal sac
has been found situated between an artery and
vein so transfixed, communicating with both, _
and permitting a transmission of blood from —
one vessel into the other. ‘This variety has
been named the varicose aneurism. AG

7. A portion of blood may be contained —
within a new and diseased formation of cellu- —
lar structure, the precise nature of which is —
not understood. ‘The trunks of the arteries in

ARTERY, PATHOLOGICAL CONDITIONS OF.

the neighbourhood are neither distended nor
ruptured, and the blood within it passes through
the general circulation, and of course does not
coagulate. It is difficult to class this disease
with aneurism in any form, yet is it termed the
aneurism by anastomosis.

No part of the natural history of any disease
can be more interesting than that which has
reference to its causes, whether predisposing
and remote, or immediately exciting. Cer-
tainly, when an aneurism has been formed, a
knowledge of the circumstances that occa-
sioned it will not be very useful in contributing
to its removal, although it may often assist in
forming a prognosis as to the result of an
operation ;: yet if it can be made available in
the prevention of the disease, it must prove of
no inconsiderable value. It is admitted that
aneurism frequently appears suddenly as the
result of a blow, a strain, or some violent exer-
tion, the patient being conscious of something
having torn or given way within him. With
still greater frequency it occurs without any
such consciousness on the part of the sufferer,
and persons have borne this formidable disease
about them for months, and even for years,
not only without being themselves aware of its
existence, but, if situated internally, without
its being recognized by their professional at-
tendants ;* and it often happens that a patient
complains of the crookening of the fingers or
the numbness of the foot, unmindful of the
tumour under the clavicle or in the popliteal
space. Without denying that an artery, in a
perfectly healthy condition, can become the
seat of aneurism, because there are too many
facts apparently in support of such an opinion,
it may be remarked that if such was generally
or even frequently the case, the disease ought to
be much more common amongst the labouring
poor, and also that it should prevail amongst
some particular trades. These considerations
lead to a belief, that previous to the occurrence
of spontaneous aneurism, the artery has under-
gone some change predisposing to it, although
it may not be so easy to point out the nature
of that change, or the causes that lead to its
production.

It is observed that aneurism is of far less
frequent occurrence in woman than in man;
a comparison between the numbers of internal
cases proving this fact in a remarkable manner,
and in cases of external aneurism still more so.
It is very rare to meet with a popliteal aneu-
rism in a female. Certainly, the more labo-
rious habits and constant exposure to accident
in the one sex may in some respects serve to
account for this circumstance, but to those
who know that in many places women are
obliged to undergo at least as much hardship
and fatigue, the explanation will be far from
satisfactory. Again, it has been stated that
certain pursuits of life predispose to aneurism,
inasmuch as it prevails amongst coachmen and
postilions, but there never has been even a
plausible reason offered to explain this greater

_ ™ A very curious case of this description is related
in the Dublin Hospital Reports, vol. v. p. 167.

231

liability of particular callings. It cannot be
the bent positions of the limbs of such per-
sons, because many other classes, studious
persons for instance, maintain similar postures
for a longer time and with greater frequency,
is not aneurism common amongst them.

either will the sudden stretching of the limb
by pressing the foot against the stirrup or foot-
board in managing the horses throw any light
upon the subject, for it is found by experiment
that no force will rupture a healthy artery short
of what would also tear asunder the ligaments
of the adjacent joints. Allowing, therefore,
the accuracy and truth of these observations,
their explanation 1s still to be sought for.

Some have supposed that old age, and the
deposit of earthy material which is formed in
the arteries at that period, are predisposing
causes of aneurism; yet, if this was the case,
the disease should be very prevalent indeed
among those advanced in life, whereas it is
in reality almost as rare as in infancy or early
youth. Of fifteen cases of large aneurism
operated on, only two had exceeded the age
of forty years, the average of all being but
thirty-one and a half; and if a larger number
of cases (inclusive of the internal forms of the
disease) were collected and compared, it would
probably be shewn to be considerably less.
With respect to the earthy deposit alluded to,
it is found between the fibrous and internal
coats closely adhering to the latter, from which
it can scarcely be separated: it is disposed in
thin lamine or plates of different sizes, the
largest being seldom greater than a spangle,
and these earthy spots are distinct and separate,
not running into or connected with each other,
and never ‘encircling the vessel with an un-
interrupted bony ring. They are supposed to
render an artery friable and brittle, and there-
fore to predispose to aneurism, and have been
considered by some to be the products of
arterial inflammation. Unfortunately the origin
and progress of this earthy degeneration have
not yet been satisfactorily traced. Scarpa*
seems to regard it as arising from the same
cause that produces the steatomatous deposit,
and states that it cannot be said to be proper
to old age, as it is sometimes met with in
patients who are not much advanced in life. I
have seen these earthy depositions in the aorta
of a female not twenty-five years of age, which
was also highly inflamed and covered with
spots of soft steatomatous deposit, but still
that is far from proof of its being the product
of active inflammation, or of its rendering the
artery weak or disposed to aneurism.

Of any number of subjects above the age
of sixty brought into a dissecting-room, three-
fourths will be found with this earthy dege-
neration in some of the arteries, yet the in-
frequency of aneurism amongst old patients
has been already remarked. Again, this de-
posit has been seen in the sac of a true aneu-
rism, a circumstance that would shew it did
not greatly interfere with the distensibility of
the arterial tunics or render them more friable,

* On Aneurism, page 90.

232

and, lastly, a large and important vessel in
this condition has been tied without its being
crushed or broken down short, and being fol-
lowed by consecutive hemorrhage. From
these observations some reasonable doubt may
be entertained of these deposits being the
result of inflammation, more particularly as,
at the period of life alluded to, there is an
evident disposition to the formation of earthy
deposits in many structures and organs as well
as in the arteries.

When a large aneurism runs its course with
great rapidity, an opportunity is frequently
afforded of observing a condition of the vessel
most favourable to the production of the dis-
- ease, and which therefore may be considered
as one of its direct or immediate causes. The
vessel in this case, on being slit up, exhibits
its internal lining membrane less smooth and
polished than in its natural state; its colour is
changed to a deep roseate carmine, and it sepa-
rates from the subjacent fibrous coat with com-
parative facility. This latter structure is also
changed in colour, but not to so bright a red
as the other. Between these coats, but more
closely attached to the internal, (for they peel
off with it,) are numerous specks of a soft
steatomatous material of a white or pale grey
colour, presenting, on a superficial inspection,
somewhat of the appearance of the calcareous
deposit already spoken of. An artery in this
condition has lost more or less of its elastic
properties; it is distended, and its calibre
increased equally around. As the arteries are
always full, the impulse of every new wave
of blood driven on the greater quantity con-
tained within the distended vessel increases its
apparent pulsation, for it is in the diastole or
expanded condition of the artery that the pulse
is felt. This loss of elasticity must obviously
weaken the vessel, and cause it to be less re-
sisting: a fact that can be proved by expe-
riment after death, when an artery so circum-
stanced will be found to yield and tear under
a distending force that would have little effect
on it if in health, and will explain how an
apparently trifling exertion may produce aneu-
rism in one man, whilst numbers of others
exposed to similar or even greater violence
escape safe and unharmed.

If arteritis can be justly considered as an
immediate cause of aneurism, it follows that
any thing tending to produce this condition of
the vessel will predispose to the disease. An
investigation of the natural history of this
affection would, therefore, prove equally useful
and interesting, but as yet a sufficient num-
ber of facts have not been collected from which
any useful practical induction can be drawn.
The experience of an individual cannot be
sufficient to establish a fixed and general posi-
tion, but may be valuable if it induces others
to a similar line of investigation, in order to its
being verified or contradicted; and from a
minute attention to the previous history of
several cases, I have frequently been able to
connect intemperance, particularly in the use
of spirituous liquors and repeated or ill-con-
conducted courses of mercury, with the pro-

ARTERY, PATHOLOGICAL CONDITIONS OF. |

ject to exposure, and too often of reckless and

duction of arteritis. How far these can explain
the comparative infrequency of the disease in
females and its prevalence amongst men sub- _

ee

%

dissolute habits, must be determined by future
observation ; but, in corroboration of latter

part of this opinion, it may be remarked, that __
few old persons are subjected toa course of
mercury that do not perish shortly after by the
bursting of a bloodvessel,—of apoplexy, or
hemoptoe most frequently.

When arteritis has proceeded to the extent
of producing these steatomatous deposits, if
aneurism is not inevitable, it is certainly very
likely to ensue. In some instances the loss of
elasticity is so great as to cause all the coats
of the vessel to yield and become distended
into the sac of a true aneurism: in others,
(and far more frequently) the process of ulce-
ration commences, the lining membrane cover-
ing one of these spots first becoming soft,
then exhibiting a distinct ulcer which proceeds
from within, eroding the middle coat either
through its entire thickness to the cellular,
which is then easily distended into the aneu-
rismal sac ; or so far as that it shall be likely
to give way and tear under a trifling shock,
even under the impulse of the circulation.
In the pathological collection of the medical
school of Park-street, Dublin, there are pre-
parations exhibiting these forms of aneurism
and the different stages of dilatation, of soft-
ening, and of ulceration in the most satisfactory
manner.

Circumscribed false aneurism.— When a
person experiences a sensation as if something
had given way or been torn within his limb,
or even without such previous warning, per-
ceives a small hard, pulsating tumour situated
somewhere immediately on the course of a large
or leading artery, it is to be suspected that an
aneurism has formed. And this suspicion is
confirmed, if the tumour becomes larger or
smaller, according to the diastole or systole
of the artery, or is diminished by pressure, or
almost disappears if the patient should happen
to faint. If pressure be applied on the trunk
of the artery between the tumour and the
heart, its pulsation ceases, its size is sensibly
diminished, and it becomes soft and flaccid ;
if on the farther or distal side of the tumour,
its size is increased, and its throbbing rendered
far more evident. The pulsation is said to
become more faint in proportion to the growth
of the tumour, and this, though generally true, —
is not so universally, for this symptom will
presently be found to be influenced by a num-
ber of circumstances, such as the blood within
the sac being fluid or coagulated, the situation —
and depth of the tumour within the limb, and
the coverings of fascia it may possess. In
most instances there is a peculiar whizzing —
sound, plainly perceptible on applying the ear
or a stethoscope to the tumour, termed by th
French the “ bruit de soufflet;”’ but its 7
sence or absence is by no means pathogno.
monic, foi it may be artificially produ y
pressure on the trunk of any large artery.

On examining a circumscribed ag

—e Ji

On

ARTERY, PATHOLOGICAL CONDITIONS OF.

after death or the removal of the limb, the
artery should, if possible, be always slit up
on the side opposite to that from which the
tumour springs. The appearances of inflam-
mation will probably depend on whether the
aneurism be recent or of long standing, and
obviously on whether it has been the result of
accident or disease. Also, if it be recent, the
aperture leading into the sac is generally well
defined, circular, and circumscribed, its edges
- remarkably thin and fine: if, on the contrary,
it is old, the aperture is large, smooth, and so
even as to present an appearance as if the
lining membrane had been prolonged from the
artery into the sac. On cutting ito the sac
some fluid blood is usually found, and always
a quantity in a state of coagulation. Besides,
there is always more or less of fibrine, the
remains of former coagula deposited in irre-
gular lamine, and varying in colour from a
pale red or grey. The most external layers
are closely fastened to the internal wall of the
sac by means of large depositions of flaky
lymph, from which, however, they can be
separated by careful washing or maceration.
This lymph thickens the walls of the sac, and
imparts to them considerable firmness and
resistance. The sac, itself, is most generally
of an oval form, but to this there are some
exceptions, amongst which the occasional oc-
currence of a dissecting aneurism is the most
curious. This happens when the internal and
middle coats having ulcerated or given way,
the blood insinuates itself between the fibrous
and cellular coats, detaching them from each
other to a considerable extent, whence the dis-
ease has derived its name.* Such is an outline
of the appearances on dissection, but they will
avail little in explaining the nature of aneu-
rism, unless combined and compared with the
phenomena of the disease during life.

And, in the first instance, it must be recol-
lected that the tumour is pulsatile, a quality
that proves the entrance of a quantity of fluid
blood, and its return back again into the artery
by the resistance or reaction of the sac. It was
this circumstance that principally led Fer-
nelius to believe and to teach that aneurism
consisted in a dilatation of all the coats of the
artery, inasmuch as he could not understand
how pulsation occurred if the tumour did not

ssess an elastic covering, and moreover
imagined that if the blood was driven into a
sac otherwise constituted, it must of neces-
sity remain there and become coagulated.
It is, however, unnecessary now to discuss the
question as to whether the sac of an aneurism
possesses elasticity or not, when it is daily
observed that any tumour (an enlarged gland
for instance) situated on an artery, and re-
ceiving an impulse from the heart, may com-
municate the sensation of pulsation, provided
the skin and other elastic tissues covering it
are sound. Nay, farther, it may be remarked
that the pulsation of an artery, even with its
elastic coat uninjured, is much more apparent

* See Dissections of Aneurism, by John Shekel-
ton, Dub. Hosp. Rep. vol. iii.

233

than real, and when felt ab externo, is greatly
influenced by the skin and its other coverings.
It is a fact too well known to every operating
surgeon to be for a moment controverted, that
an artery when exposed exhibits nothing like
the force. of pulsation that it did before the
skin was divided ; sometimes it is difficult to
ascertain it satisfactorily at all. The late Pro-
fessor Todd has strongly pointed out this
circumstance in his case of axillary aneurism,
published in the third volume of the Dublin
Hospital Reports, where he says, “‘ For some
time I could not be convinced that the feebly
pulsating vessel, to which the point of my
finger was applied, was really an artery of such
magnitude as the subclavian ;” and similar
observations could be adduced, if necessary,
from other sources.

It is of little consequence, then, whether the
aneurismal sac possesses an elastic covering
proper to itself or not, the resistance of the
external structures being sufficient to explain
the phenomenon of pulsation, and the impor-
tance of the integrity of these structures in the
progress and termination of the case is ex-
tremely interesting. If even a small quantity
of blood was thrown at each pulsation of the
heart into a yielding, unresisting bag, it must
of necessity remain there, and in a very short
space of time the accumulation would be
enormous; but if there is a re-acting force
capable of returning a portion of this blood
and restoring it to the circulation, the accumula-
tion and consequent growth of the tumour will
be measured by the quantity of blood thus left
behind. The volume of blood sent into an
aneurismal sac must be proportioned to the
aperture through which it has to pass, while
the actual quantity lost must depend not so
much on this as on the non-resistance of it and
its coverings, and their incapability of return-
ing the fluid back into the circulation. Hence
the growth of external aneurisms is in general
rapid or slow according as they have existed a
greater or less length of time; for in old aneu-
risms the aperture into the sac is generally
large, and the elasticity of the external coverings
is weakened by over-distension.

The pathology of aneurism arranges itself
under two distinct orders, one having relation
to the open and bleeding artery, the other con-
sequent on the hemorrhage being internal.
This latter circumstance is interesting to the
surgeon, because the presence of the blood in the
limb, the position it occupies, and the pressure
exercised by it on the adjacent structures and
organs, very often form the most prominent and
important features of the disease, and nearly
as frequently cause the destruction of the patient
as the bursting and bleeding of the tumous.
But the consideration of this part of the sub-
ject does not immediately belong to the patho-
logy of the arterial system, to which these re-
marks are more particularly directed. To re-
turn, then, to the open or ruptured artery. The
condition of the vessel is scarcely different
from that of one wounded by a knife. It is a
bleeding artery, and the same principle that is
applicable to hemorrhage under any other

234

circumstances is also available here, for if a
wound of this species of vessel cannot heal
whilst its calibre remains open, neither can an

aneurism be cured until the artery from which.

it springs is completely obliterated at the spot
where the aperture into the sac exists. ‘The
complete closure of the vessel is to be accom-
plished by placing its opposite walls in contact
and under the influence of such pressure as
will occasion inflammation and the effusion of
coagulating lymph,—a pressure that can be
applied either ab externo by means of com-
press and bandage, or from within, by placing
the blood in the sac in a condition that will
admit of its perfect and complete coagulation.

_ Pressure on the tumour, if it could be ex-
actly applied and firmly maintained, ought to
succeed, and, in truth, has often been success-
ful, particularly when the disease is consequent
on a wound ; but there are so many difficulties
to be surmounted and dangers to be encoun-
tered in its use, that few entertain much confi-
dence in it, and perhaps it never would be
resorted to but from a dread of consecutive
hemorrhage after a ligature. A bandage, if
applied with sufficient firmness to operate with
rapidity, occasions such excruciating pain that
it can scarcely be endured ; and if loosely, it is
liable to slip ; and if even it does finally work a
cure, the progress of the case is so protracted
that many patients become wearied with the
trial. Again, the large trunks of arteries
throughout the extremities are generally accom-
panied by nerves and veins in such close
apposition with them, that a compress can
scarcely be applied to one without interfering
with the other; and instances have occurred of
dreadful mischief having been occasioned by
interruption of the venous circulation in such
cases, even in the course of one night. Finally,
pressure has very frequently caused the rupture
of the sac, and the aneurism, from being cir-
cumscribed, has suddenly become diffused ;
and if there was no other source of apprehension
but the possibility of this latter occurrence, it
should make a surgeon pause before he adopted
so hazardous a mode of treatment.

Pressure from within is effected by re-
moving the impulse of the heart from the
blood within the sac for a sufficient time to
permit of the sac becoming perfectly filled with
blood, and for that blood to become coagulated.
This object will be accomplished by interrupt-
ing the flow of blood under the impulse of the
heart through the leading trunk of the vessel
for a given time: in cases of small aneurisms
forty-eight hours being sufficient, but the larger
and older requiring a longer period. A ligature
placed around the vessel between the tumour
and the heart effects this purpose; but it does
more than is requisite, for it divides its in-
ternal and middle coats, occasions the effusion
of lymph and the obliteration of the artery
there, and involves the risk of consecutive
hemorrhage afterwards on its final separation.
To avoid these inconveniences, the presse artere
of Deschamps and a number of other con-
trivances for arresting the flow of blood through
an artery, and admitting of easy removal after

ARTERY, PATHOLOGICAL CONDITIONS OF.

the object has been accomplished, have been
proposed and tried, but success has not been
sO great as to warrant their general adoption,
and the operation by ligature is still very
generally preferred. It may be applied either
at the cardiac side of the tumour, when it acts
in the manner above stated, or between the
aneurism and the capillary circulation, in which
case the principle of its operation is somewhat
different.

In the former instance, when a ligature is
applied to the trunk of an artery, the supply
of blood to the limb below it is interrupted for
a few moments; the aneurism loses its pulsa-
tion, and sinks and diminishes in size more or
less according as its contents had been fluid or
coagulated. Soon the blood begins to flow
through the collateral branches, and enters the
aneurismal sac also, but it passes into it slowly
and without impetus, and no part of it is again
forced back into the circulation. It coagulates
and comes to press upon and close the ruptured
vessel, which is soon obliterated by lymph, and
in process of time becomes degenerated into
little more than a ligamentous cord. A beau-
tiful illustration of this entire process was seen
in Mr. Crampton’s case* of ligature of the com-
mon iliac artery. The patient had two aneu-
risms, one of very large size at the groin, the
other in the popliteal space of the same limb,
firmer, and of much smaller dimension. A liga-
ture of catgut was placed round the common
iliac, which either rotted or by some accident
became detached on the sixth day: the pulsa-
tion returned in the larger tumour, which soon
afterwards burst, and the patient perished. The
sac of the popliteal aneurism being so much
smaller had time to become perfectly filled with
blood, which was there coagulated and firm.
The ligature had accomplished all that was
necessary for it, and the cure would have
been complete even although the ligature had
loosened—whilst the opposite was the fact with
reference to the larger tumour.

Sometimes, soon after the ligature has been
applied, pulsation reappears in the tumour.
This must always be considered as an untoward
circumstance, but does not necessarily involve
the failure of the operation; for it may take
place under two different conditions of the
parts. 1. In aneurisms of very long standing,
in situations where there is a free and extensive
collateral circulation, probably increased by the
pressure of the tumour. In these the pulsation
does not return for some time after the vessel
has been tied, and is never so strong as before
the operation. It may continue for several
days, but gradually diminishes in force, and at
last ceases. The progress of the case then
resembles that of the ordinary forms of the dis-
ease, except that in this the cure is much
more protracted. Apparently, such was Sir
A. Cooper’s first successful case + of ligature of
the common carotid artery, as also the case of
carotid aneurism published in the fifth volume
of the Dublin Hospital Reports.{ It is not un-

* -Medico-Chirurg. Transactions, vol. xvi.

+ Medico-Chirurg. Transactions, vol. i.
¢ Page 208.

ARTERY, PATHOLOGICAL CONDITIONS OF. 235

likely that Mr. Turner’s case of aneurism in
the fore-arm, in which he secured both radial
and ulnar arteries, was of a similar description
also. 2. Where by an irregular distribution
there exist two trunks in the limb, both con-
veying blood to the aneurismal tumour. Sir C.
Bell had a case of popliteal aneurism in the
Middlesex Hospital, in which, just below the
origin of the profunda, the femoral artery
divided into two branches of nearly equal size,
which ran parallel to each other until they
arrived at the spot where the artery perforates
the tendon of the triceps muscle, and there they
united again. Only one of these was tied, and
although the pulsation in the tumour ceased
for a moment, yet it soon returned, and never
disappeared until the patient’s death, which
happened a few days afterwards, from erysipelas.
A preparation of a similar distribution is pre-
served in the Museum of the Royal College of
Surgeons in Dublin;* and it is quite clear that
where such exists in an aneurismatic limb, the
securing of one of the trunks could produce no
benefit.

It has been already stated that one of the
effects of the ligature on an artery is the eventual
obliteration of the entire calibre of the vessel
between it and the nearest collateral branch at
each side, and, therefore, it might be supposed
that if it be tied immediately close beyond an
aneurismal sac in such wise that no branch
shall intervene between the cord and it, the
whole of the canal to the next branch, in-
cluding the spot where the rupture had taken
place, ought to become obliterated, and the
aneurism thus be cured. ‘This is the principle
that led to the performance of the operation of
tying the artery at the distal side of the aneu-
rism. It was (I believe) originally proposed by
Delpech, and put in practice by Desault, but
the termination of the case gave little en-
couragement for future trials, and it fell into
disuse until of late years, when it has again been
tried in England, and still subsequently by
Mott, in New York, but not with a success to
justify its general adoption. There is but one
artery in the body (the common carotid) so
circumstanced as to answer the design of the
operation ; and even in this, if the smallest and
most trifling branch happened to intervene be-
tween the aneurism and the ligature, it must
defeat the principle of the operation altogether,
and perhaps tend to aggravate the disease.

rue aneurism.—Two different pathological
conditions of an artery have been regarded as
constituting this disease; one in which the
entire circumference of the vessel is distended,
forming a tumour of an oval shape, pulsating
strongly during life, and not containing coagu-
lated blood: the other is where all the coats of
an artery at one particular spot are dilated in
such wise as to form a sac springing from the
side of the vessel, and containing blood with-
drawn from the circulation, and in a state of
coagulation. Perhaps it would be more cor-
rect to regard the former of these as a state of

* There is a similar preparation in the Museum
of St. Bartholomew’s Hospital.—Ep.

vessel predisposing to the formation of a false
aneurism, whilst the latter, presenting during life
the same phenomena, and curable on the same
principles that have been already laid down,
must be considered as offering truly a specimen
of the disease.

When in consequence of arteritis, or from
any other cause, the elasticity of the arterial
structure becomes impaired or weakened, a
dilatation of the vessel at the spot so debilitated
ought to be the result; and this probably takes
place in all arteries previous to the formation
of idiopathic aneurism. But the circumstances
that determine an artery to become dilated
rather than to ulcerate are very obscure, for
the same morbid appearances in the vessel are
observed to precede both. In the eleventh
number of the Dublin Journal of Medical
Science there is an account of two cases of
internal aneurism, one formed by ulceration of
the internal and middle coats of the artery,
which burst into the csophagus; the other,
evidently by dilatation, which destroyed the
patient by pressure on the trachea: and in
both the aorta exhibited the same appearances
of inflammation and steatomatous deposit be-
neath the lining membrane. The preparations
are preserved in the collection of the school in
Park-street, and as showing this pathological
fact are extremely satisfactory. Again, it is
not easy to say what dilatations should be con-
sidered aneurismal or not. The aorta, in a great
proportion of subjects above the age of forty,
is dilated; yet such dilatation is not regarded
asananeurism. Other arteries presenta similar
appearance occasionally; and a case occurred
not very long since in the Meath Hospital, in
which all the arteries of the inferior extremities
in an aged man were dilated to more than
twice their natural calibre. These vessels were
found after death filled with coagulated blood,
yet as the fluid seemed to circulate through
them during life, and the patient never ex-
perienced any inconvenience, it is difficult to
admit them as specimens of true aneurism.
On the other hand, nearly at the same time, a
man died in another hospital who for years
had a small aneurism of the femoral artery,
with every observable symptom of the disease
except that the growth of the tumour was un-
usually slow; and on dissection this appeared
to have been a species of true aneurism, caused
by an equal dilatation of the entire circum-
ference of the vessel, and did not contain coa-
gulated blood. It would seem, then, impos-
sible to pronounce during life on the reat
nature of an aneurismal tumour, nor is it always.
easy to demonstrate it after death.

In most instances of aneurism, particularly
those of long standing, the edges of the aperture
into the sac are smooth and even, and the lining
membrane seems to be prolonged into it. The
internal wall of the sac is so thickened, and all
the parts so matted together and confused by
depositions of lymph and fibrine, that the
appearances altogether become so deceptive as
almost to countenance the old opinion as to the
pathology of the disease. Professor Scarpa,
who principally opposed the doctrine of aneu-

236 ARTERY, PATHOLOGICAL CONDITIONS OF.

rism by dilatation, was obliged to support his
opinions more by argument than by facts de-
monstrable by dissection ; and although later in-
vestigations, particularly those of Mr. Hodgson
and Mr. Guthrie, have satisfactorily proved the
occasional existence of both true and false
aneurism, yet it must be a favourable case and
patient examination that will enable the morbid
anatomist to exhibit its nature and structure
without possibility of error. When cases of
inflamed or diseased artery are seen, compli-
cated with aneurism, and the same depositions
are observed in the artery and in the sac, it
proves beyond doubt the identity of structure
in both. Thus, if an aorta be found studded
over with specks of a soft steatomatous deposit
situated between its internal and middle coats,
and if on one side of it an aneurism is placed,
in the sac of which, throughout its entire ex-
tent, the same appearances and the same de-
posit are observed, it follows that the same
structures must exist in both, and that one is
a prolongation of the other. One of the cases
already noticed as being a true aneurism, that
destroyed the patient by pressure on the trachea,
exhibited such evidence of its nature: and a
similar one, but still more satisfactory, occurred
in the person of a gentleman, who died some
years since. This patient had laboured under
some anomalous cerebral symptoms, and on
inspecting the brain a small aneurismal tumour
was seen at the bifurcation of the basilar artery,
in the sac of which were found the same kind
of earthy depositions that pervaded all the
arteries of the body-——the same so generally
observed in the arteries of aged persons. These
examples are sufficient to prove that aneurism
by dilatation may exist, and perhaps its occur-
rence in the aorta and larger vessels is more
frequent than has been supposed.

During the past spring two opportunities
occurred of examining into the nature and
condition of aneurism, both in its early stage
and long after it had been apparently cured by
operation. They were, probably, both ex-
amples of what has been termed true aneu-
rism, although unquestionably all the coats of
the artery were not engaged: and as the mor-
bid appearances have not been hitherto de-
scribed, it may be useful to take notice of
them here.

A man was admitted into the Meath Hos-
pital, with popliteal aneurism in each ham:
one of these had existed for several weeks ;
the other was of very recent occurrence. The
limb in which the older and larger one was
situated was first made the subject of opera-
tion, the femoral artery was tied, but the
patient died on the sixteenth day afterwards,
of venous inflammation, the ligature on the
vessel still remaining firm and undetached.
On examining the aneurismal tumour exter-
nally it appeared of an oval shape, and to have
been formed by the gradual expansion of all
the coats of the vessel. On being cut into,
however, it was found that the lining mem-
brane was wanting throughout the entire extent
of the sac, the edge of it terminating sharply
and abruptly, above and below, at the junc-

tions of the tumour with the more healthy

rts of the vessel, and being as accurately

efined as if made by a careful dissection.
The fibrous coat was evidently continued into
the tumour, which seemed to be formed of au
expansion of it and the cellular. It was, 3
moreover, otherwise diseased, being thickened,
greatly softened and thrown into irregalar rugee
or folds, the interstices between which were
filled with coagula of lymph or fibrine. As
the sac of this aneurism was in a state of sup-
puration, the deficiency of the lining mem-
brane was attributed to that circumstance until
the other aneurism came to be examined when
the same appearances were observed. The
second tumour was not so large as a walnut
and evidently formed by the gradual expan-
sion of the fibrous coat, for the abrupt ter-
minations of the lining membrane at the
healthy extremities of the artery were sti!l more
exactly defined.

The other case is even more interesting, be-
cause it exhibits a cure of aneurism after
operation in a manner that has not been de-
scribed, the principle of which it is not easy
to understand. A man was operated on by
Mr. Collis, in the Meath Hospital for popliteal
aneurism on the 22d of January, 1831. The
ligature came away on the seventeenth day, the
tumour diminished ; in short, every thing went
on well and the patient left the hospital per-
fectly cured. So far as the aneurism was con-
cerned, he remained healthy and free from
inconvenience until his death, which hap-
pened in March 1835, from fever, and such an
opportunity for pathological inquiry was not
neglected. The tumour which had been origi-
nally of the size of a turkey’s egg, was found
to have diminished to little more than that of a
walnut: externally it felt hard and as if com-
pletely solidified: on being cut into, however,
neither artery nor sac was obliterated, the latter
being occupied by a coagulum of a deep red
colour, through the centre of which was a canal
of a sufficient size to allow the blood from the
portion of the artery above the tumour to flow
freely into that below it. It seemed as if the
current of blood through the sac had never
been interrupted, the only effect of the former
ligature having been the removal of the im-
pulse of the heart from it. This aneurism
appeared to have been a true one, so far as the.
fibrous and cellular coats were concerned, but.
the fact could not be so satisfactorily demon-
strated as to admit of no dispute ; however,
the absence of the lining membrane and its
sharp and abrupt terminations at the healthy
portions of the vessel were sufficiently ob-
vious.

If it be difficult to demonstrate the nature
and constitution of the small and recent aneu-
rism, it becomes impossible when the tumour
has attained to a considerable size. It seems
probable, however, that the arterial structures.
will not long endure this state of unnatural
distension, and they either uicerate or tear in
their internal and middle coats. A mixed
aneurism will thus be formed, having its sac at
first composed of all the structures of the artery,

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ARTERY, PATHOLOGICAL CONDITIONS OF. 237

and subsequently in the largest portion of its
circumference, of the cellular coat alone. ‘The
long continuance and gradual increase of some
aneurisms, as contrasted with their sudden and
rapid growth afterwards, have been explained
on this supposition.

Diffused aneurism.—An aneurism is termed
diffused when the blood, removed from the
circulation, is not confined within a pouch or
sac, and therefore passes in every direction
throughout the cellular tissue of the limb.
This may be occasioned by the rupture or
ulceration of an aneurismal sac, but far more
frequently by some violence applied to the artery
itself in such a manner as to open its cellular
as well as its other coats. Thusa spicula of a
fractured bone, or a pointed sequestrum, in
coming from a puat limb, may produce the
disease ; but the most common examples that
fall under a surgeon’s observation are furnished
by awkward or ignorant persons in their at-
tempts to perform the operation of phlebotomy.
In the latter case there is an external wound
communicating with the injured vessel, and
then it also presents a familiar illustration of
traumatic aneurism.

When the blood is thus diffused throughout
the cellular tissue, there is always the greatest
danger ; not so much from the loss of a large
quantity to the circulation as from the rapidity
with which a limb so circumstanced runs into
a gangrene,—a rapidity so great that the mor-
tification either is not or seems not to be pre-
ceded by inflammation, and its occurrence is
often the first notice a surgeon receives of the
extent and nature of the accident. When the
injured artery lies deep and is covered by a
dense and resisting fascia (as in the instance
of the posterior tibial artery being ruptured by
a blow), it may bleed for some time without
affording any indication beyond the pain and
tension complained of by the patient, and a
slight tumefaction of the limb. When, how-
ever, the fascia has yielded or sloughed and per-
mitted a more extended diffusion of the blood,
the part becomes swollen, glassy, and cedema-
tous, pale if the blood did not occupy the
cellular tissue underneath, but of a livid colour,
like that of a bruise, if it does. The joints
in the neighbourhood are kept flexed, and any
attempt at motion gives intolerable pain. Ina
very short space of time circumscribed spots
of gangrene appear, which, on separating, per-
mit masses of very dark coagula to protrude,
accompanied by an oozing, or perhaps, a flow
of arterial blood, under which a patient will
very soon sink. And it may be, the real nature
of the case has not been suspected until this
blood has made its appearance. Doubtless, if
a diffused aneurism has been occasioned by a
wound, the rush of blood at the moment, its
colour, and the difficulty of controlling the he-
morrhage will point out what has happened ;
or if there had been a circumscribed aneurism
that on a sudden lost its defined character
while the limb began to enlarge above and below
it, there would be good grounds for suspicion ;
but in any other case it is so difficult to sepa-
rate the pain and tension and the other symp-

toms from those which might naturally super-
vene on a severe injury, that the appearance of
a tendency to gangrene is too often the first
circumstance to create alarm. There are many
symptoms in which the diffused aneurism
differs from the circumscribed, that render
the diagnosis of the former particularly difti-
cult. It has been already stated that the
* bruit de soufflet” is, even when present, not a
pathognomonic symptom, and if the vessel lies
deep it is not to be heard at all. Pulsation of
the tumour, the most satisfactory symptom of
an aneurism, is generally absent, and when
otherwise, is very weak, fluctuating, and indis-
tinct. To those who reflect that the effused
blood is thrown out amongst inelastic and
unresisting structures, that no portion of it is
returned to the circulation, but that it lies
a coagulated mass amongst the surrounding
cellular tissue, the absence of these symptoms
will not require explanation.

Traumatic aneurism.—But if, as very fre-
quently happens, the accident that caused the
aneurism has also created an external wound
communicating with the injured vessel, and
permitting the escape of a portion of the blood
through it, although still a diffused aneurism,
the leading circumstances of the case are
essentially altered. This is the form of disease
termed by the French traumatic aneurism,
the name having reference not so much to
the fact of its having been produced by
violence, as to the co-existence with it of a
solution of continuity in the skin and other
structures external to the vessel. Thus, although
an aneurism may be caused by the prick of a
lancet in the bend of the arm, or by a bayonet-
wound in the thigh, yet if the external wound
is healed, or, being unhealed, if it is so oblique
or devious that the blood flowing from the
artery does not escape from the limb, it may
not be called traumatic, whilst a common pop-
liteal aneurism that had arisen spontaneously,
if it is accidentally opened, assumes the cha-
racter just designated. The chief peculiarity
of this case, then, is the external wound, and if
it be conceded that it is the resistance of the
unyielding structures that presses the coagu-
lum against the vessel, and thus accomplishes
the cure of those forms of aneurism already
described, it will be seen that a material part
of the process must be deficient, and, therefore,
that the principles applicable to the former
cannot be made available here.

In order to the proper understanding of this
part of the subject, it will be necessary to take
a familiar case for illustration. A person in
attempting to open a vein in the arm strikes
his lancet into the artery, and is, perhaps,
unconscious of the extent of the mischief he
has occasioned. The arm is tied up, but it
swells and becomes intolerably painful. When
the bandage is removed, the wound is found
not to have united, and a coagulum is pro-
bably seen plugging it up, which loosens occa-
sionally and allows the escape of a considerable
quantity of red and florid blood. In the
meantime the diffusion throughout the limb
is extending in every direction, and the hemor-

238

rhages from the external aperture are more
frequent. If this case is treated by ligature
at a distance from the situation of the aneu-
rism, although the patient may appear relieved
at the moment, that relief is but delusive. The
blood may coagulate, but being unsupported
by any external resistance, it cannot make suf-
ficient pressure on the orifice of the bleeding
vessel. Fresh blood is carried round by the
collateral circulation, and as it constantly oozes
from the punctured artery, it disturbs the coagu-
lum in the neighbourhood, and bursts out into
new and repeated hemorrhages until the sur-
geon is obliged to end where he ought to have
begun, by cutting down (if he has still the
opportunity) directly on the injured part of the
vessel, and tying it above and beléw the aper-
ture. The great difference between the trau-
matic aneurism and the other forms of the dis-
ease is, that in it the hemorrhage is external as
well as internal, and that the coagulum within
the limb being unsupported may press out-
wards through the wound more freely than
inwards upon the vessel. The coagulum,
therefore, is not available in the cure, and
the treatment must have reference to the
wounded artery alone. If the radial artery
was opened and bleeding freely from the ex-
ternal orifice, few surgeons would think of
taking up the brachial high in the arm, know-
ing that the inosculating branches would still
supply abundance of blood to the wound,
and although the pathology of traumatic aneu-
rism is somewhat different, inasmuch as a
portion of the blood lost still remains within
the limb, yet the principle of treatment is
unchanged.

It may be objected that in very many in-
stances of traumatic aneurism success has at-
tended the application of a ligature on a dis-
tant part of the artery ; but every one of these
cases will require to be accurately examined
before the treatment here laid down can be
impeached. The definition of traumatic aneu-
rism must be borne in mind, and that it im-
plies not only the existence of a wound, but of
one through which coagulated blood may pro-
trude and fluid blood may trickle. The only
case in which such practice could succeed is,
where, after the ligature had been tied, a suffi-
cient degree of pressure ab externo could be
maintained to lay the opposite sides of the
wounded artery together, and produce sufficient
inflammation to procure its complete oblitera-
tion,—in short that it shall effect that which
the resistance of the skin and fascia and
other superincumbent structures would have
accomplished in a limb less injured. Such
pressure as this must occasion intolerable suf-
fering; and experience has proved, in nume-
rous instances, how little reliance can be

laced on it.

Secondary hemorrhage.—Hitherto the ap-
plication of a ligature has been noticed only
as a curative process, its advantages have been
discussed, and the manner in which it may be
supposed to operate explained ; but it has been
also stated that “the ligature is in itself not
infrequently a cause of great and fearful mis-

ARTERY, PATHOLOGICAL CONDITIONS OF.

chief,” and as the consideration of the different —
cases that might require the operation has been —
just concluded, perhaps this may be a fit op-
portunity for examining into the nature of these
unfavourable cases. Secondary or consecutive
hemorrhage occurs, as its name implies, at
some period subsequent to the application of
the ligature, and the blood flows from the place
where the vessel has been tied. In many
instances the patient has a kind of presenti-
ment. of that which is about to happen, and
becomes restless, uneasy, and agitated; in
other instances there is not the slightest warn-
ing, and the first notification of the mischief is
the appearance of the dressings soaked in blood.
In general it has been stated that it is on the
Separation of the ligature that this bleeding
takes place, but this is not the fact, for com-
monly it happens whilst the cord is fixed and
firm, and three or four days before its fall
ought to be expected. The longer the ligature
remains, provided no nerve or fascia had been
included with the vessel, the safer the patient is,
and it must be rare to meet with secondary he-
morrhage after the cord has become detached and j
been quietly withdrawn. It isremarkable thatthe
blood comes from the inferior portion of the
artery; it wells up abundantly from the bottom
of the wound, and never flows with a gush or
per saltum; it is easily restrained by pressure
on the bleeding orifice; and if such pressure is
accurately applied, and can be maintained

uring a very few days, the cure is permanent, :
and the patient would be safe but for a number 7
of collateral circumstances, which, however :
important in the management of the case, form, }
properly speaking, no portion of the pathology
of arteries.

Various causes have been assigned as pro-
ducing secondary hemorrhage, the chief of which
is the too extensive detachment of the vessel
from its surrounding connexions during the
operation, an opinion that I cannot think is borne
out by observation. If it is supposed that this
dissection of an artery is injurious by depriving
it of its vascularity, and diminishing its supply
of nutrient blood, the result should be analo-
gous if not exactly likethat which takes place
when the vessel is deprived of its cellular coat
from any other cause, that is, a slough should
form on it, on the separation of which the
hemorrhage should occur violently and with
a gush. An illustration of this is familiarly
observed in the phagedenic ulceration of buboes
in the groin, where the artery for a time appears
to resist the destructive process, and lies de-
nuded like a white cord at the bottom of the
sore; but oneor more black spots form upon it,
which are really specks of mortification, on the
detachment of which the bleeding commences
with awful violence. Perhaps consecutive
hemorrhage does occasionally occur from the
burrowing of an abscess along the coats of an
artery, an example of which is on record in —
Mott’s case of ligature of the imnominata, in
which the bleeding occurred ten days after its
removal, was so violent from the first as to
be with much difficulty restrained, and de-
stroyed the patient on the day but one after-

ARTERY, PATHOLOGICAL CONDITIONS OF.

wards. But it may be observed that the phe-
nomena attendant on these cases are different
from those already described as characteristic
of the common forms of the accident—that
they usually occur at a later period, even long
after the separation of the ligature might have
inspired confidence in the result, and they are
evidently more hopeless, for neither pressure
nor ligature can here be of the slightest avail.
Farther, to appeal to experience, the best and
surest foundation of every scientific principle,
is it not a matter of daily observation that this
much-dreaded insulation of the artery can have
but little effect on the ultimate termination
of the case, as operations performed in this
respect in the most bungling and clumsy man-
ner occasionally end well, whilst the utmost
caution in not exposing more of the artery than
will barely permit the passage of the ligature
cannot ensure the patient from secondary he-
morrhage ?

When the bleeding is occasioned by any
defect in the operation, such as tying the cord
too loosely, including adjacent structures, &c.
it usually appears so early as from the third to
the fifth day after the operation, and there is
another form of early consecutive hemorrhage
that occurs in consequence of the artery itself
being inflamed or otherwise diseased at the
time of the operation. An example of this is too
often met, when, as a means of controlling con-
secutive hemorrhage, a fresh ligature has been
tied on the trunk somewhere higher up or
nearer to the heart. It has been remarked by
Dupuytren, that an artery under such circum-
stances is in a most unfavourable condition for
an operation ; it is surrounded by cellular tissue
in a state of inflammation, in which it par-
ticipates ; its coats are rendered so brittle that
they break down immediately under the liga-
ture, and the hemorrhage returns in a few
hours.* It is worthy of remark that in this
case also the bleeding comes from the orifice
of the vessel below the ligature; indeed, in all
cases of divided artery, whether by a cutting
instrument or by a cord, the remedial process
seems to be different in the two fragments,
being far more perfect in the upper. On this
point the statements of Mr. Guthrie are most
valuable because founded on extensive ob-
servation, and he remarks in the case of an
artery, the bleeding from which had ceased of
itself, that if it recurs it is more likely to
proceed from the lower than the upper portion.
This latter fact is the more important as it bears
upon another supposed cause of secondary
hemorrhage, namely, the state of tension in
which an artery inclosed in a ligature is ne-
cessarily placed.

Many years ago it occurred to Mr. Aber-
nethy that, “as large arteries do not ulcerate
when they are tied upon the surface of a stump
after amputation, it would be right to tie them
in cases of aneurism as nearly as possible in
the same manner and under the same circum-
stances.” It is familiarly known that he re-
commended for this purpose the application

* Legons Orales, tom, iv. p. 573.

239

of two ligatures with the division of the arte

between them; and he argues that the divided
portions would be like the large vessels on the
surface of the stump in possession of all their
surrounding connexions, whilst they are left in
a lax state in consequence of their division.
But the cases after all are not analogous, be-
cause in the stump there is no inferior portion
of vessel from which it has been seen the
chief cause of apprehension arises—it has been
cut away, and only the superior remains, from
which it is rare to meet with hemorrhage
under ordinary circumstances. In Mr. Aber-
nethy’s operation it is only the upper division
of the vessel that bears analogy with the artery
of the stump, and the insufficiency of the
removal of*the tension in preventing hemor-
rhage from the inferior is proved, first, by the
fact that consecutive hemorrhage occurs in
cases that have been thus treated proportion-
ally as often as in others; and, secondly, by
Mr. Guthrie’s observation that in the case of
a wound there is no tension: the artery has
been fairly divided, and its surrounding con-
nexions are undisturbed; yet the bleeding,
having ceased spontaneously, or, in other words,
having been controlled by the power of nature ~
alone, may recur, and when it does the blood

’ flows from the lower orifice.

Others have believed that the accidental
position of a collateral branch near to the
ligature might be a cause of consecutive
hemorrhage by interfering with the formation
of the internal coagulum. I have already
stated that the importance attached to this
coagulum was greater than it deserved; and it
will be only necessary here to add, that I have
tied the common carotid artery within an
eighth of an inch of its origin from the inno-
minata without the slightest ill consequence
from that circumstance.

It has been pretty generally believed that in
those cases which have ended favourably,a mi!d,
healthy, and mitigated process of inflammation
had been established which terminated in the
effusion of lymph and the obliteration of the
vessel, whilst in the unfavourable the inflam-
mation was more violent and ran into ulce-
ration. Nothing is more familiar than to hear
of the ulceration of an artery in connexion
with and as the cause of secondary hemor-
rhage, yet the existence of such ulceration is
very questionable. Arteries are not prone to
ulcerate. It has been shewn that in the midst
of phagedenic destruction, the artery escapes
for a length of time, and when it is attacked,
it is rather by mortification: and the appear-
ance of arteries traversing in safety the cavities
of tubercular abscesses in the lungs, where
they have lain for weeks or months bathed in
purulent matter, should make us hesitate in
speaking so boldly of ulceration in these struc-
tures. The fact, as observed on dissection,
appears to be quite otherwise, and the hemor-
rhage to be occasioned not by a hyper-activity
of inflammation tending to ulceration, but by
an absence or failure of the process altogether.

As persons, the subjects of consecutive he-
morrhage, seldom die (at least in this country)

240

of actual loss of blood, it is not easy to pro-
cure a dissection which can satisfactorily shew
the condition of the vessel at the moment it
begins to bleed, and no subsequent examination
can be relied on, because the pressure or other
means used to stop the bleeding may in the
course of a very few days alter the appearances
completely. 1 have availed myself of every
opportunity that occurred, and state the results,
not with the presumptive hope of being able
to establish any general principle, but to excite
others to inform themselves on every case fa-
vourable to the further prosecution of the in-
quiry, and, perhaps, in some respects to justify
the opinions I have formed. It is worthy of re-
mark, that secondary hemorrhage occurs much
more frequently in the arteries of thé lower than
of the superior extremities or of the neck, and
all the specimens I have examined were of the
femoral that had been tied from half an inch
to an inch and half below the profunda. In
all, the portion of the artery above the ligature
gave indications of inflammation extending
nearly as high as the common iliac; the lining
membrane more or less vascular; the portion
of the vessel between the ligature and profunda
of its natural size or slightly diminished ; its
cavity occupied by the remains of a coagu-
lum. Above that point the calibre of the
trunk was evidently increased, and the texture
of its coats less resisting. The inferior por-
tion resembled a vessel simply cut across,
its calibre diminished, its internal -coat dis-
coloured, its divided edge smooth and even,
not rough, jagged, or irregular, as would pro-
bably be the case if it had been the seat of
ulceration.

When a ligature is tied tightly round an
artery, every thing included within its noose
is killed, but this is only a very small ring of
the cellular coat, the internal and middle being
as completely divided as if it had been done
with a knife. When the absorbents have de-
tached the connection of this ring with the
remainder of the cellular coat, there is nothing
(so far as the vessel is concerned) to retain it
farther, nor is it of use in preventing hemor-
rhage: it might be withdrawn, only that being
entangled in lymph or granulations from the
adjacent parts, such a proceeding would dis-
turb the divided vessel before the curative
process was complete. This process is in some
instances, perhaps, never attempted in the
inferior portion, although such a deviation
from the usual course is probably not frequent ;
when it does happen, the cure is more tedious
and longer of accomplishment, and when inter-
terrupted prematurely, of course it is from this
portion that the blood is poured out.

Whatever the process is by which the ex-
tremities of the two segments are closed, it is
certainly not the same in both. This fact I
was enabled to verify in one of the cases al-
-ready alluded to,—namely, that of the man who
died on the sixteenth day after the operation
for popliteal aneurism, and whilst the ligature
still remained undetached from the artery.
The vessel was carefully removed from the
body, and on being slit up, the lining mem-

ARTERY, PATHOLOGICAL CONDITIONS OF.

brane of the portion at the cardiac side of the —
ligature was of a pale yellow colour and nearly
of its natural appearance, with the exception
of one or two broad spots of a very light pink
colour. A large coagulum extended upwards
from the seat of the ligature, the base of which —
was attached to the lymph situated there. The
ligature was still firm, but on attempting to
tear it away, the lower portion of the vessel
easily separated from it, leaving it still fixed —
firmly on the upper section: a circumstance
which explained a fact I had frequently wit-
nessed, that of secondary hemorrhage occur-
ring before the final separation of the cord.
Below the spot where it had been tied the
vessel appeared to be of a deep pink colour
approaching to carmine, the seat of which
colouring matter was in the cellular tissue
between the fibrous and internal coats. This
cellular substance seemed to be hypertrophied
and largely congested with blood, whilst it
caused the lining membrane to be thrown into
transverse rugz or folds. On pulling off this
membrane, it was pale, transparent, and colour-
less—devoid of any proper vascularity: and
on looking along the slit-side of the vessel the
fibrous coat and the internal membrane were
seen like white lines with the congested cellu-
lar tissue between them. There was not a
particle of coagulum either of blood or lymph
wn any portion of the vessels below the liga-
ture.

It may be objected that in this very dissec-
tion, the appearances would warrant a belief
that a more active form of inflammation was
present in the distal portion of the vessel,
because of the deeper tint of colour and the
superior thickness of the cellular tissue there
observed. Such, however, was not the im-
pression of those who witnessed the dissection.
There was no result of inflammation visible
after seventeen days, neither adhesion, nor sup-
puration, nor ulceration: there was merely a
congested condition of the part—a condition
not found in other structures or situations to
lead to any of the usual products of inflam-
mation.

An artery, the coats of which have been
divided by a ligature, is subject to the same
conditions as if it had been severed with a
knife: its cavity must be obliterated from the |
wounded spot to the next collateral branch
above and below. Now, the constitutional
causes that can delay or impede this oblite-
ration, if any, are not sufficiently known; but
it is obvious that any local interference may
(as ina case of open hemorrhage) prove sin-
gularly perilous. During the first few days,
whilst the continuity of the cellular coat is
still unbroken, there is no cause for apprehen-
sion; but afterwards, any irregularity of diet,
any excitement of the circulation, any unwary
motion, any injudicious meddling with the
ligature ; in short, any one circumstance that
can interfere with or disturb the operations of —
nature within the part before they are perfect —
and complete, will have a much more intimate _
connexion with the production of secondary
hemorrhage than any of the causes hitherto —

aa « ai 2 —

a wr pe eS ee

ARTERY, PATHOLOGICAL CONDITIONS OF.

advanced. fence it is, that the bleeding
occurs some two or three days earlier than the
period at which the ligature naturally separates
and comes from the wound.

When the bleeding has commenced, it is a
case of hemorrhage from an open wound, and
must be managed on similar principles, that is,
pressure to a sufficient extent must be applied
directly on the orifice of the vessel. i ave
never seen a second ligature applied on the
mouth of the vessel, either in consequence of
the difficulty of finding the artery in a wound
swollen and matted up with lymph and gra-
nulations, or from an apprehension of the ex-
istence of such a diseased condition of its coats
as would cause it again to break down under
the cord. But I have frequently witnessed
the effective operation of direct pressure, par-
ticularly in three cases, which occurred within
the last few months, two of which were
patients in the Meath Hospital, and all of
whom recovered. In the application of this
Agere however, much caution is required.

t should not be greater than is absolutely
necessary to command the hemorrhage; it
ought to be maintained by means of some me-
chanical contrivance, and be independent of all
bandages which are liable to stretch, to loosen,
or to slip, and it should be removed the very
moment this can be done with safety. If the
bleeding has been perfectly restrained during
three or four days, it is probable it never will
return. The sequelae of secondary hemor-
rhage ought always to have been regarded as
more important and more perilous than the
bleeding itself. I have invariably found the
wound to become the seat of unhealthy sup-
puration: very frequently abscesses form in
different parts of the limb, and occasionally
gangrene supervenes. It is sometimes diffi-
cult to connect any of these occurrences with
a lesion of any structure within the limb ; but
too frequently the mischief can be evidently
traced to the pressure being directed on the
vein, and being either too forcible or too long
continued.

Having thus, however imperfectly, sketched
the pathology of the arterial system in con-
nexion with the use of the ligature, it will be
necessary to revert to other forms of disease,
which have hitherto been postponed, in order
to permit the introduction of the subject of
secondary hemorrhage, and that the practical
arrangement of aneurism and its consequences,
both fortunate and otherwise, might be as un-
interrupted as possible.

Aneurismal varix.—In the year 1761, Dr.
William Hunter* directed the attention of the
profession to a disease that had not been before
observed, one not indeed very formidable in
its consequences, but exceedingly curious as to
its exciting cause and subsequent progress.
When an artery and vein lying in close con-
tact are transfixed by a cutting instrument in
such a manner that the aperture in one shall
exactly correspond with that of the other; and

* Medical Observations and Inquiries, vol. i.
and ii.
VOL. Me

241

when subsequent inflammation has so glued
and fastened these apertures together, that,
whilst a mutual transmission of blood between
the vessels is freely permitted, not a drop will
be allowed to escape in any other direction,
a disease is formed, to which the discoverer
gave the name of aneurismal varix. All and
each of these several conditions are absolutely
indispensable, and there are so many chances
of their not being fulfilled im a case of
wounded artery, that the infrequency of the
disease may be easily explained. It does,
however, occasionally occur, and for obvious
reasons will most generally be found in the
arm as a consequence of phlebotomy.

Soon after the infliction of the injury that
has been the cause of the disease, a small
tumefaction is observed in the vein; its ap-
pearance is irregular and knotted, but it is soft,
yielding, and disappears on pressure. On
laying the finger on it, a peculiar thrilling sen-
sation is perceptible, and on applying the ear,
a whizzing noise is heard, very much re-
sembling that occasioned by a fly inclosed in
a small paper bag. These phenomena dis-
appear on either current of blood being in-
terrupted by pressure on the artery above or
on the vein below: at the same time that the
tumour subsides a little, (though it soon regains
its original size) and the peculiar noise is no
longer heard. If the disease is allowed to
advance uninterruptedly, the calibre of the
artery above the point of communication be-
comes enlarged, but it is diminished below: the
vein also enlarges chiefly in the direction of
the current of its blood, rarely in the opposite,
and then but very slowly. Another interesting
circumstance is, that the peculiar thrill is
heard and felt all over the dilated portion of
the vein, at a distance from, as well as in the
immediate neighbourhood of, the point of
communication between the two vessels. It
seldom produces any inconvenience that can-
not be remedied by the use of a moderately
tight bandage, and if thus managed in time
never requires a severer treatment.

From the circumstance of pressure, either
on the artery or vein, diminishing the size of
the tumour and removing the thrilling sen-
sation it imparted, it may be fairly inferred
that both these phenomena are produced by
the meeting of the two currents of blood, and
their mutual resistance to the escape of either
from its proper vessel. And further, it is ob-
vious that if the disease should by any chance
prove troublesome or alarming to the patient,
its growth might be checked and its progress
altogether stopped by permanently obliterating
the canal of either the artery above or the vein
below: but no operation that a surgeon would
be justified in undertaking can remove the
tumour, inasmuch as the blood still will con-
tinue to flow into and through the enlarged
vein. The dangers of secondary hemorrhage
after an artery is tied, or of venous inflam-
mation if the other vessel is tampered with,
ought to inculcate the greatest caution, and it
may be easily understood why in such cases
Dr. Hunter thought it advisable not to interfere.

R

7"
Sh ate

242 ARTERY, PATHOLOGICAL CONDITIONS OF.

_ This disease must, in the great majority of
instances, be the result of accident, and its
ceipaan situation has been already pointed out,

ut it is also possible that it may appear as
an idiopathic affection without any previous
violence. Some years since a young female
applied at the Meath BS as an out-

atient, in whom aneurismal varices existed

etween every artery and vein in the body that
lay in a state of approximation to each other.
In the neck, in several parts of the arms, the
thighs, &c. the peculiar thrill and sound were
remarkably distinct and plain. She did not
seem to experience much uneasiness, nor could
any probable exciting cause be assigned for
such a singular form of disease. She had pre-
viously suffered from syphilis and been sub-
jected to irregular mercurial treatment, but it
would be scarcely fair to assume as the cause
of a solitary specimen of disease in one indi-
vidual, influences that operate so very differ-
ently on others.

Varicose aneurism.—W hen a vein and artery
communicate with each other in a manner
similar to that already described, excepting that
an aneurismal sac formed of condensed cellular
tissue and containing some coagulated blood is
interposed between their orifices, the disease is
termed a varicose aneurism. As this disease is
generally the result of some accident in bleed-
ing, as it occupies the same situation at the
bend of the arm, and as the sac in that case never
attains to any considerable size, it is difficult
and frequently impossible to distinguish during
life between the two affections: nor is the
diagnosis of much importance, for as the patho-
logical changes in the artery and vein, and the
phenomena produced by them, are exactly the
same, so will be the rationale of the treatment.

Some few years since, a patient was admitted
into the Charitable Infirmary with a popliteal
aneurism of the size of a child’s head, and
with all- the veins of the limb, particularly of
the thigh, enormously distended so as to appear
like ropes twisted and knotted under the in-
teguments. In every one of these veins the
peculiar thrill and sound of aneurismal varix
could be distinctly perceived. The account
he gave of himself was this: he had a pulsating
tumour in the ham for fourteen years previ-
ously, which gradually increased to its present
size, until the veins began to swell, when the
large tumour becaine stationary. He expe-
rienced but little inconvenience, and said he
was able to walk eleven or twelve miles a day.
He was frequently permitted to leave the hos-
pital, and exhibited himself to several profes-
sional men for money. As he refused to sub-
mit to any treatment, and indeed no operation
held out a prospect of much benefit, he was
soon discharged. This man (I believe) still
lives, and as he resides in a distant part of the
country, perhaps the true pathological nature
of a case so very interesting may never be
ascertained. Could it have been that this was
originally a case of popliteal aneurism that had
burst into the popliteal vein? The position of
this vein, and its very intimate connexion with
the artery, cause it to appear to be a part of the

‘ *t ftp By
sae of every popliteal aneurism, and it is no
difficult to conceive that the tumour mis Aye:
given way in this particular situation, | ny a

Pee

~*~

communication been thus established bie.
the artery and vein through the medium of
aneurismal sac. ca

It may not be unimportant to observe, that
rare as these latter forms of disease areacknow-
ledged to be, they are still more so in reality
than is generally imagined. It often happens
that a congeries of knotted and contorted veins”
forms a tumour strongly resembling the aneu-—
rismal varix in its external characters, and im-
parte similar sensations of thrill and sound.

f one of these happens to occupy a situation
favourable to the production of aneurismal varix,
it might easily occasion a mistake, and perhaps it
would be very difficult to point out a satisfactory
diagnostic. I have seen two of these tumours
dissected, which during the lives of the patients
were supposed to have been aneurismal varices,
in neither of which could the slightest commu-
nication with any neighbouring artery be dis-
covered.

Aneurism by anastomosis.—The disease which
was so named by John Bell, and by him first
placed in the class of aneurismal tamours, has
no title to such a position, unless that it forms
a reservoir of blood, and occasionally exhibits
the phenomenon of pulsation. But it mate-
rially differs in that the blood contained within
it is fluid, is not withdrawn from the circulation,
and therefore does notcoagulate. The circum-
stances, however, of these tumours being in-
creased or diminished in size by those influ-
ences which excite or depress the activity of
the circulation, and of the leading trunks of
the vessels supplying them having, however
erroneously, been made the subjects of opera-
tion for their cure, serve to connect them in :
some respects with the pathology of arteries, and
justify a passing notice of the subjecthere. This
kind of tumour has also been called the nevus
maternus or mother mark, because it so often
appears from birth or at a very early age, and
its shape, colour, size, or situation is explained
by the mother on the supposition of some sub-
stance having been thrown at her, or from other
causes of affright. It may, however, appear
for the first time in more advanced life, in the
form of a speck or pimple, which gradually
enlarges until it constitutes a disease of a most
important and sometimes dangerous nature.

The external characters of aneurism by anas- ~
tomosis are somewhat varied, and have admitted —
of its classification under three forms apparently
distinct from each other: 1. Where the mark —
or stain is merely cutaneous, does not increase —
in size, and is never pulsatile. These marks”
may be of different colours, sometimes
sometimes of a brassy yellow, or perhaps brown;
and as they occasion no inconvenience beyond
the unsightliness of their size and situatio
they can scarcely bé considered as diseas
Indeed, if the common mole be admitted w
der this class of nevi, in many instances
seems to constitute a beauty rather than a
2. Where the disease is situated in b
skin and sub-cutaneous cellular tissue. —

‘ be i

ah Ble ll Mit As Le be AP

Fd
>
>

ARTERY, PATHOLOGICAL CONDITIONS OF.

appears as a patch, slightly elevated, of a red
or purple colour, being generally of a brighter
hue on the face or breast, and darker on those
parts usually kept covered. The colour of the
nevus also seems to depend on the quality of
the blood with which it is altogether or prin-
cipally snpelied as sometimes tumours are met
with which might be termed venous aneurisms
of this description, consisting evidently of
veins indurated, knotted, and contorted on
each other, increasing gradually, and never pul-
satile; these frequently occur in different parts
of the body of thesame individual,and are always
attended more or less with pain. The arterial
nevus is, however, most intimately connected
with the present subject. It sometimes pre-
sents an appearance as if irregularly granulated ;
more frequently is itsmooth and velvety. The
deep stain possesses a sharp and circumscribed
edge, yet a net-work of minute vessels may be
seen like an areola around it, conveying blood
to nourish the tumour, and therefore forming
an important part of the diseased structure.
The tumour is increased in size and intensity of
colour by every thing that accelerates the circu-
lation—by exercise, intemperance, paroxysms
of passion, and even by an elevation of tem-
perature, and hence the supposed marks of
currants and other fruits are said to grow red
and ripen at the proper season. Its feel is
doughy, and communicates a sensation as if it
contained a jelly. It sinks, and is diminished
by pressure on its surface, but immediately the
ressure is removed it recovers its former level.
t may be stationary for years, but the contrary
is generally observed ; ‘its growth, however, is
always irregular, being more rapid at one period
than another. 3. The distinguishing charac-
teristic of the third form of nevus is its pulsa-
tility. It beats synchronously with the heart
and arteries. When wounded, blood of a
bright red colour flows from it, often in such
abundance as to occasion syncope or even more
dangerous consequences. As it grows larger,
the skin gradually becomes thin ; it bursts and
bleeds ; masses of coagula lie upon its surface,
putrefying and occasioning the most unsightly
appearance and most offensive odour. This
is a condition that cannot endure long, the
patient soon becomes irritable and weak, and
falls a victim to that irregular, ill-formed hectic
which is seen in every disease accompanied by
extensive hemorrhages. Itis manifest that the
distinctions between these latter forms of nevi
are merely artificial ; the second can be made
to pulsate and to increase by heat or intem-
rance,'the third can often be restrained by cold,
y abstinence, and other means that debilitate
the circulation.
The external appearances, however, yield no

information as to the condition of the parts
_ within, or the nature of this newly-formed struc-
_ ture; and on this subject anatomical investiga-
tion affords but little satisfactory knowledge.

When a nevus is extirpated, it seems to consist
of a mass of cellular tissue, collapsed and
id, which cannot be unravelled, and seems

to bear no proportion in size to that of the

243.

tumour before removal. If it be cut away
close to its defined edge, and without the ex-
tirpation of the zone of small vessels already
described, the bleeding is frightful, and in very
young children may be fatal, evidently shewing
that these vessels are not endowed with con-
tractility, and are a diseased and a new forma-
tion. Ifa nevus is injected, it only affords a
swollen and unshapely mass of whatever ma-
terial had been used, and throws no light what-
ever on the real pathology of the disease. Here,
then, in the absence of demonstration, theory
and conjecture are permitted, and all that is
known, or supposed to be known, is only the
fruit of speculation.

Bell supposed the tumour to consist of a
congeries of cells, into each of which an artery
and vein opened; that these cells imcreased
both in number and in size with the growth of
the patient, until they became immense reser-
voirs of blood; and, finally, that they became
so distended as to burst and destroy life, as any
other aneurism would, by a profuse discharge
of blood. But still this explanation is defec-
tive,as showing nothing of the nature of the
cells themselves, or why blood poured out into
them should not coagulate as it would in any
other cellular structure. It remained for Du-
puytren to offer an ingenious and extremely
probable hypothesis relative to these points,
and he conceived the aneurism by anastomosis
to be a “tissu erectile,” analogous to that
naturally found in many parts of the body.*

In the penis of man, and in the clitoris
and mamella of woman, there is a particular
structure, capable of receiving, retaining in a
fluid state, and afterwards returning a given
quantity of blood. ‘These organs are provided
with strong fibrous sheaths, that prevent their
distension beyond a certain size, and are fur-
nished with a number of nerves that preside
over the circulation through them, and deter-
mine their conditions of erection and col-
lapse. The abnormal “ tissu erectile” consists
of a cellulated structure, in itself of the same
ora similar structure, but not being invested
by a fibrous sheath or capsule, its growth is
unrestrained, and the size to which it may
attain has no limit; and as it has not a similar
distribution of nerves, there is nothing to occa-
sion either unwonted distension or collapse, and
it is left solely under the influence of those
causes that act upon the circulation. (See

* The late Mr. Shekelton of Dublin injected one
of these tumours with wax from a large artery in
its vicinity, and corroded away the animal matter
by immersing it in a weak acid solution, by which
it was shewn to consist of a congeries of vessels
arranged in a retiform menner, dilated at some
points and contracted at others. An able and in-
teresting paper was read on this subject, and on
the tortuosity of arteries generally, to the medical
section of the British Association, which lately
met at Dublin. The great attainments of its author
(Mr. Adams) in pathological science lead us to
look, not without some degree of impatience, for
the full publication of the paper, of which but an
imperfect report has appeared in the Dublin Medical
Journal for September 1835.— Eb. 5

R

244

EReEcTILE lena? Thus an aneurism by
anastomosis is made to increase by heat, by
sion, or by excess of any description, and
y the removal of these, or by the application
of opposite influences, its growth may be
checked, or its pulsation stopped. But when
once formed, it remains for ever, unless re-
moved by spontaneous ulceration, by adhesive
inflammation of the cells, or by operation; for
although, if the general circulation be depressed,
that in the tumour will be less active also, yet
the structure is there still unaltered and ready
to receive the blood and to exhibit all its
wonted phenomena whenever the requisite sti-
mulus is applied.

BIBLIOGRAPHY. — Cowper, on ossifications or
ent aoe of the coats of arteries; Phil. Trans.
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Paris, 1819; Hjus, Engravings to illustrate some
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ARTICULATA.

Annali ~universali, 1821. Dalbant, De Varterite
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Journ. de Progres. Gendrin, Hist. anat. des in-
flammations, tom. Paris, 1826. Dezeimeris,

Memoire, &c. Apergu rapide des découvertes en
anatomie pathologique, 8vo. Paris, 1829. * * * *
Turner, on the sudden spontancous obstruction of
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Journ. vol. xxix. 1828. * * * * Manzoni,
Consid. sugli anevrismi; Mem. della Societa Ita-
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Vanevrysme spontané, 8vo. Paris, 1825. Mayer,
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Schonberg, Sul ristabilmento della circolazione
nella legatura, &c. dei tronchi delle arterie, Napoli,
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vulnerate et ligate fuerint, 4to. Giesse, 1826.
The papers of Lawrence and Travers on the ligature
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Med.-Chir. Trans. Zhuber, Neue Versuchen an
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Bertin, Hope, Bouillaud, and Otto’s Compend. of
pathological anatomy, by South,

(W. H. Porter.)

ARTICULATA (articulus, a joint,) a pri-
mary division of the animal kingdom founded
by Cuvier,* and characterized by him as follows:
“ Body jointed externally, corresponding to the
divisions of the nervous system internally: a
very small brain placed above the cesophagus
gives off two filaments which extend along the
abdomen and unite together from distance to
distance by means of ganglions, which resem-
ble as many small brains, from which nerves
are given off. The muscular system is disposed
on the inside of the rings or segments of the
body so as to separate and approximate these
segments ; when there are articulated mem-
bers, the muscles of these parts are also placed
within the hard parts. The divisibility of the
body, and the power which the fragments
possess of retaining a kind of independent

* This division was virtually established by Cuvier

in his earliest work, the ‘‘ Tableau Elémentaire de

VHistoire Naturelle des Animaux,”’ although it was 1
not defined with that clearness, nor its characters
so fully developed as in the Régne Animal. In the

‘“Tableau Elémentaire ” the second section of
* white-blooded animals,’ including the Insecta and

part of the Vermes of Linneus, corresponds pre- —
cisely with Lamarck’s division of invertebrate —

animals, which he first denominated ‘ Articulosa.’

Mite 3 Nat. des Animaux sans Vertebr. tom. i. p.

——

oe eS eee

ARTICULATA. | : 245

vitality corresponds to the distribution of the
nervous system into as many centres as there
are corporeal segments.””* ith respect to the
agreement between the number of segments of
the body and the ganglions of the nervous sys-
tem, it must be observed that in the higher
crustaceans, arachnidans, and insects, the gan-
glions, though originally as numerous as the
segments, subsequently become concentrated
by progressive development into masses which
are fewer in number, and that also in some of the
lowest annelidans, as the leech-tribe, the ex-
ternal segments are more numerous than the
internal ganglions.

In many of the molluscous class two nervous
cords proceed backwards from the supraceso-
ore ganglion or brain, and are afterwards

rought into communication by ganglionic
masses on the ventral aspect of the body ; but
in the Articulata the uniting ganglions are

_ always confined to the mesial line of the body,

are perfectly symmetrical in their arrangement,
and are accompanied by a symmetrical or bila-
teral form of the whole bedy. It is this homo-
gangliate disposition of the nervous system
which essentially distinguishes the Articulate
from the Molluscous and other divisions of the
Animal Kingdom, and it is an infallible guide
to the true affinities of the classes possessing
it. The Cirripeda present a striking example
of this fact: these animals, on account of their
inarticulate body enveloped in a fleshy mantle
and protected by a multivalve shell, were for

a long time classed with the mollusca: but

the views of those naturalists who considered
that they had closer relations to the Arti-
culata, although that opinion was founded on
a knowledge of their nervous system only, has
since been corroborated by every additional
fact which has been discovered respecting
them. Latreille, in his “ Familles Naturelles
du Reégne Animal,” first placed the cirripeds in
the Articulate series, but being guided by their
adult organization, and supposing that they
were deficient in visual organs, and underwent
no metamorphosis, he joined them with the an-
nelidans, to form a division of Articulate ani-
mals, “ Elminthoida,” distinct from the “ Con-
dylopeda,” which include the insects, arach-
nidans, and crustaceans, or the Articulata with
jointed feet. The later researches of Mr. I. V.
Thompson and Dr. Burmeistert have proved
that in the immature state the Cirripeds un-
dergo repeated metamorphoses or moults ; that
they move freely in the water by means of
setiferous articulated members, and during this
period guide their wanderings by the aid of
distinctly developed, though simple eyes.
Besides the cirripeds the higher organized
infusoria and intestinal worms have been
proposed by some naturalists to be added to
the articulate division of Animals: but as they
are neither articulated nor possess articulate

" See his celebrated memoir, “ Sur un nouveau
rapprochement 4 etablir entre les classes qui com-
posent le régne animal.” ** Annales du Muséum
@ Histoire Naturelle, 4to, tom. xix. p. 73. }

t Beitrige zur Naturgeschichte der Rankenfuesser,
Ato. Berlin, 1834.

members, and as thei nervous cords are sim-
ple and not brought into communication by a
regular series of ganglions, we prefer to leave
the Rotifera and Ceelelmintha with the Entozoa
and Echinodermata, as a separate and higher
subdivision of Cuvier’s Radiata, and thus pre-
serve the Articulata as a distinct and well de-
fined subkingdom, characterized by a dispersion
of the nervous system in a series of ganglions,
symmetrically arranged and brought into com-
munication by a double nervous cord ; by an
articulate or jointed structure of the body or its
appendages, by the lateral position and hori-
zontal movements of the jaws, when these are
present, and by the presence of distinct respi-
ratory organs. The subdivisions of this sub-
kingdom are not founded on the modifications
of any single system, but principally rest on
the conditions of the sanguiferous and respira-
tory organs, in connexion with exterior form,
modes of locomotion and generation.

I. The Cirripeds, (cirripedia, cirripeda, cir-
rhopoda) ; oceanic animals called barnacles
and acorn shells: they are characterized by
their fixed condition, being either sessile, or
attached to foreign bodies by means of a
ewan te their generation is, consequently,

rmaphrodite, without the intercourse of se-
parate individuals, but the male and female
organs are distinctly developed in each animal.
The blood is colourless and is propelled by a
dorsal vasiform heart, but the venous system is
diffused. The branchiz are internal. The cir-
ripeds undergo metamorphoses, but are ulti-
mately inclosed in an inarticulate defensive
covering of shelly pieces varying in number,
form, and size.

Il. The Annelidans, ( Annelida, red-blooded
worms, ) are always locomotive; and, conse-
quently, although hermaphrodites, they enjoy the
intercourse of the sexes, and reciprocally fecun-
date each other. Their blood, which is gene-
rally red, like that of the vertebrate animals,
circulates in a closed system of arteries and
veins, which sometimes has appended to it
several well-marked propulsive cavities or
hearts ; they respire by means of organs some-
times developed externally, sometimes remain-
ing on the surface of the integument, or lodged
in its interior. Their body, which is of an
elongated form, and covered with a soft skin,
is always divided into numerous transverse
segments, of which the first, called the head,
scarcely differs from ‘the others, except by
the presence of the mouth and of the principal
organs of the senses. Many possess branchie,
arranged the whole length of the body, or situ-
ated at the middle; others, which for the most
part inhabit tubes, have the branchiz collected
at the anterior part of the body; in others,
again, the respiratory organs are in the form of
internal air sacs. The annelidans never possess
articulated limbs, but many have, instead thereof,
stiff bristles, or hooks, frequently inclosed in
tubular prolongations of the integument.

The other urticulate classes, viz., insects,
arachnidans, and crustaceans, differ from the
preceding classes in the possession of arti-
culated limbs, terminated by claws; and in

246

‘connexion with the superior powers of loco-
‘motion afforded by these appendages, the sexes
are separate, and the organs of vision are
well developed, and often highly complicated.
‘With the exception of some genera, as the
myriapoda, in which the body is divided into
a number of nearly equal segments, and of
the arachnida and many crustacea, in which
the head and thorax are blended together, the
body of the condylopes of Latreille is divided
into three principal parts, viz., the head, which
bears the antenne, the eyes, and the mouth;
the thorax, which supports the feet and the
wings, when the latter are present; and the
abdomen, which contains the principal viscera.

These segments present different degrees of
hardness in the different classes of condylopes,
being most flexible in the arachnidans, firmer
in the insects, and calcareous in most of the
crustaceans. The origin of the insections or
articulations of the body which form so marked
an external character of these animals, is as
follows :—

The integument is composed of two layers or
pellicles, viz., the epidermis and the corium,
and is originally of equable consistence, and
presents an uninterrupted continuity, save by
some slight transverse superficial wrinkles.
The epidermis subsequently becomes solidi-
fied, in arachnidans and insects, by the super-
addition of a peculiar substance termed chitine,
and in crustaceans by a calcareous deposition,
so as to be divided into bands or rings. As the
external development proceeds, these epidermic
pieces are detached posteriorly from the inferior
pellicle, or corium; and the intervals of the
segments remaining membranous, and presery-
ing their flexibility, yield readily to the various
movements and inflections of the body.

The [11d class of articulate animals or In-
sects ( Insecta ), are either myriapod or hexapod.
Most of the latterare furnished with wings, which
they acquire at a certain age, after undergoing
metamorphoses varying in kind and degree. In
every state they respire by trachee, or elastic
vessels which receive the air by stigmata, situ-
ated along the sides of the body. A dorsal
vessel propels the circulating fluid, which is
afterwards diffused throughout the cellular
tissue of the body. They have conglomerate or
compound eyes, and antenne.

IV. The Arachnidans ( Arachnida, Spiders,
Scorpions, &c.), are octopod and apterous;
they have no antenne, and have simple eyes.
Their circulation is effected by a dorsal vasi-
form heart which transmits arterial branches,
and receives the returning blood from veins.
Their organs of respiration vary, some pos-
sessing true pulmonary sacs which open upon
the sides of the abdomen, others receiving the
air by trachez, like insects. In both cases,
however, the air is respired by lateral orifices
or true stigmata.

V. The Crustaceans ( Crustacea.) have never
less than ten feet; they have two compound
eyes, and also antenne, which are generally
four in number; their blood, which is white,
is circulated by means of a muscular ventricle
situated on the back, They respire by means.

ARTICULATION.
of gills, and have no stigmata, or sp

‘such variations in it as are, in each case, de-

the surface of the skin. “ay erp

In the Articulate sub-kingdom, as in the
tebrate, there may be traced one general ple
of structure pervading all the classes, but wi

manded by the particular exigencies of the —
individual to which it is applied; but these
variations are of such a nature, that a gradation —
of complexity or perfection may be followed
through all the organic systems. With regard
to locomotion, we commence with a class (the
Cirripeds) as fixed and immoveable as the
polypes and sponges of the Acrite sub-king-
dom; and afterwards trace a series of forms
adapted first to slow and tortuous reptation ;
next to swifter progression, as creeping, run-
ning, or leaping; and, lastly, to a rapid flight —
through aerial space. ’

Generation, in like manner, is effected, inthe
lowest class, without the intercourse of separate
individuals; afterwards by the reciprocal im- —
pregnation of co-equal hermaphrodites, and,
lastly, as in the vertebrate division, by indi-
viduals of distinct sexes.

The perfection of the nervous system results
from the approximation of many separate gan-
glions into fewer masses of nervous matter. The
organs of the senses also augment in number
and complexity. .

The Articulata present, in the organs of the
vital functions, as strongly marked differences
as are met with in the vertebrate animals.
With respect to the sanguiferous system, a
gradation may be traced from a circulation
in closed vessels to a diffused condition of
the nutritious fluid ; and a corresponding pas-
sage from the articulata which respire by
means of circumscribed branchie, to those
in which indefinitely ramified trachee carry
the air to all the parts of the body. The ©
amount of respiration thus produced occasions
the same effects here, as in the Vertebrate
sub-kingdom, and the Insects thus constitute,
as it were, the Birds of the Articulate division
of animals.

( Richard Owen. )

ARTICULATION (in anatomy), synony-
mous with joint. (Gr. appv. Lat. articulus,
arthrosis, junctura. Fr. articulation. Germ.
Articulation, Gelenk. Ital. articolo ). :

The power of motion, to an extent however
limited, seems to be inseparable from our idea —
of an animal, and in looking through the animal
series we find none which do not appear to be ~
endowed with this power whether for the pur-
pose of progression, or simply of altering the po- —
sition or condition of some part of their bodies
with respect to the others. The organic struct
which is the immediate agent in this moti
power (the muscular fibre), is one and the sam
throughout the whole chain of animal:
riously modified according to the degre
force of the motions necessary for the p:
individual. The mechanism by wh
structure acts upon the different pe
body varies considerably, and in
complexity as the forms of the animals

ah
2° ia

ARTICULATION.

selves become more complex. In the lowest
grade of animals the structure is so soft and
pliant that nothing more is required to produce
motion than this contractile tissue, which acts
in obedience to certain stimuli. But when
hard parts are superadded to the structure
of the animal, we then find a peculiar me-
chanism to allow of the motion of these hard

ts on each other without the risk of injury.
It is obvious that such motion could not take
place were these hard parts united in one piece.
Hence we find that they are subdivided into
segments, and these segments are joined to
each other through the medium of some struc-
ture_more flexible than that of the segments
themselves, or by an apparatus of such a con-
struction as to admit of the motion of one
segment upon the other. It is to these join-
ings of different segments of an animal body
that the term articulations or joints has been
applied.

An articulation may, therefore, be defined to
be the union of any two segments of an animal
body through the intervention of a structure or
structures different from both.

The most perfect and elaborate forms of
articulations are those which are seen in ani-
mals that possess a fully developed internal
bony skeleton, and in none may they be studied
with more advantage thaninman. We propose
to treat of the forms and structure of the ar-
ticulations in man, and at the same time to in-
quire what modes of mechanism are employed
for analogous purposes in the lower classes.
In the human subject and in the vertebrated ani-
mals generally, we shall, indeed, have particular
occasion to admire the articulations, as mira-
biles commissuras, et ad stabilitatem aptas, et
ad artus finiendos accommodatas, et ad mo-
tum et ad omnem corporis actionem.*

It will be observed that the definition here
given of articulation is of the most compre-
hensive nature. In most instances, in man, two
parts articulated together are joined by their
solid portions, which are never in immediate
apposition with each other, but have some
elastic structure interposed which may or may
not form a bond of union; and it is obvious
that the fact of the intervening substance being,
or not being also a bond of union will greatly in-
fluence the extent of motion of which the joint
is capable. Before inquiring into the variety
of forms of joints, we shall first examine briefly
the various structures which enter into their
composition, and which essentially contribute
to the perfection of their mechanism.

These parts may be enumerated as follows,
and we propose to observe the same order in
treating of them:—41. Bone. 2. Cartilage.
3. Fibro-cartilage. 4. Ligament. 5 Synovial
membrane. )

1. Bone.— The osseous or an analogous
Structure constitutes the fundamental portion
of an articulation in all the vertebrated animals,
in the mollusca, and in some of the articulated
classes. In the human subject and all ver-
tebrated animals we find that certain parts of

* Cicer. de Nat. Deor, 1. ii. c. 35.

247

the bones have surfaces marked upon them
in correspondence with similar surfaces on
others with which they are connected, or
that, as in the long bones, the extremities
are expanded or enlarged, and present sur-
faces which are adapted to similar surfaces
on contiguous bones. In this way are formed
the articular portions of the bones, and we
observe that these portions present considerable
varieties in their characters according to the
nature of the articulation which they con-
tribute to form. In fact, in examining these
articular portions of the bones we cannot fail
to notice the diversity of their form, so that
some are adapted to each other in such a
manner as evidently to favour motion, and
Others are so framed as to limit and restrict it.
The articular surfaces in dry bones are ge-
nerally characterised by a peculiar smooth-
ness, indicative of the existence on them of
a cartilaginous incrustation in the recent con-
dition. The expansion of the extremities of
the long bones on which the articular surfaces
are formed is to be attributed to the accu-
mulation there of a considerable quantity
of the reticular texture, covered by a thin
lamina of compact tissue, whereby a large
surface is obtained without the inconvenient
increase of weight which would necessarily
result did that portion of the -bone contain
compact tissue to any extent. In the neigh-
bourhood of the articular portions of the bones
we find certain eminences, depressions, or rough-
nesses, which indicate the points of attach-
ment of those bonds of union by which the
joints are secured and strengthened. In ge-
neral it may be observed that the long bones
are articulated with each other by joints which
poet a considerable extent of motion; the flat
ones, again, have articulations very limited in
their mobility, and this is likewise the case
with the irregular bones.

2. Cartilage —Pure cartilage enters into the
composition of almost all joints, but more
particularly of those which are very moveable,
and indeed the chief purpose for which it is
employed in the economy of adult animals is
as an important and valuable element in these
moveable joints. Articulur cartilage, there-
fore, constitutes a primary subdivision of this
texture by systematic writers. Its hardness,
its elasticity, and the limited degree of or-
ganization which it possesses, peculiarly adapt
it for the purposes to which it is applied in the
mechanism of the articulations.

Although cartilage is chiefly employed in
those joints which possess considerable mo-
bility, it nevertheless also exists in joints which
are limited in their motions, and as it possesses
peculiar characters according as it belongs to
one or other of these classes of articulations,
we may very conveniently subdivide it into—
a, cartilage of moveable articulations, or ar-
ticular cartilage properly so called, or diar-
throdial cartilage; 6, cartilage of articula-
tions very limited in their motions, or cartilage
of sutures, or synarthrodial cartilage. Under
these heads we propose to treat of articular
cartilage,

248

a. Diarthrodial cartilage. — The general
characters of this class of articular cartilage
may be best examined on the articulating ex-
tremities of the long bones. Here we observe
it moulded exactly to the forms of those sur-
faces, insomuch that, after a little maceration,
the cartilage may, by careful dissection, be
removed from the bone, to which it adheres
with great firmness, and will be found to ex-
hibit an exact mould of the articular ex-
tremity ; hence these cartilages have been called
“cartilages of incrustation.” ‘This cartilage
is perfectly distinct at the early periods of life
from the temporary cartilage which forms the
nidus of the future bone, and cannot be re-
garded as a portion of that cartilage left un-
ossified ; this may easily be seen by examining
a vertical section of a femur or tibia at this
period ; and the peculiar arrangement of the
fibres of the articular cartilage, hereafter to be
noticed, constitutes an additional proof that it
is completely distinct from that which is after-
wards transformed into bone.

The physical properties and general charac-
ters of this form of cartilage do not differ from
those of the others; it possesses the same
pearly whiteness—the same apparent homoge-
neousness of structure—the same elasticity—the
same absence of vessels carrying red blood. It
is not covered by a perichondrium ; the surface
towards the joint is peculiarly smooth and glis-
tening, and is generally supposed to owe these
properties to its being lined by a layer of the
synovial sac of the joint; this point, however,
has been controverted, as we shall notice in a
subsequent part of the article. The first and
the most complete investigation of the true
anatomical construction of articular cartilage
was that announced by Dr. William Hunter so
long ago as 1743.* His paper still deserves
the most attentive perusal, not only for the
actual information it affords on its professed
subject, but as a specimen of the careful and
original method of observation pursued by its
distinguished author. To examine the structure
of articular cartilages, it is necessary to subject
them to boiling or along-continued maceration.t

“ When an articulating cartilage is well pre-
pared,” says Dr. Hunter, “ it feels soft, yields
to the touch, but restores itself to its former
equality of surface when the pressure is taken
off. This surface, when viewed through a
glass, appears like a piece of velvet. If we
endeavour to peel the cartilage off in lamelle,
we find it impracticable, but if we use a certain
degree of force, it separates from the bone in
small parcels, and we never find the edge of
the remaining part oblique, but always perpen-
dicular to the subjacent surface of the bone.
If we view this edge through a glass, it appears
like the edge of velvet, a mass of short and
nearly parallel fibres rising from the bone, and
terminating at the external surface of the carti-
lage: and the bone itself is planned out into

* Of the Structure and Diseases of Articular
Cartilage, Phil. Trans. vol. xlii.

+ The articular cartilage on the patella may be
selected as very inwnuante for this purpose. See
the plate annexed to W. Hunter’s paper.

ARTICULATION

small circular dimples where the little bundles
of the cartilaginous fibres were fixed. Thus
we may compare the texture of a cartilage to
the pile of velvet, its fibres rising up from the
bone, as the silky threads of that rise from the
woven cloth or basis. In both substances the -
short threads sink, and bend in waves upon
being compressed, but by the power of elasti-
city recover their perpendicular bearing as
soon as they are no longer subjected to a
compressing force. If another comparison
was necessary, we might instance the flower
of any corymbiferous plant, where the flosculi
and stamina represent the little bundles of
cartilaginous fibres, and the calyx, upon which
they are planted, bears analogy to the bone.” *
The total absence of vessels capable of car-
rying red blood in articular eartilage is proved
by the failure of even the minutest injections to
pass into the cartilage, and a further confirma-
tion of this opinion is derived from the fact
that madder taken into the system of a young
animal does not stain them. The attempts of
anatomists to trace lymphatics and nerves into
this structure have been equally unavailing.

The design of articular cartilages, as means
to break the violence of shocks, is well illus-
trated by comparing the different arrangement
of the cartilaginous incrustation on convex arti-
cular surfaces from that on concave. In the
former, we observe the layer of cartilage to be |
very thin at the circumference of the articular
surface, its thickest portion being in the centre,
while the opposite arrangement obtains on con-
cave surfaces: there the thinnest portion of the
cartilage is in the centre, and the layer increases
in thickness as it approaches the circumference.

“ The articulating cartilages are most hap-
pily contrived to all purposes of motion in
those parts. By their uniform surface they
move upon one another with ease: by their
soft, smooth, and slippery surface mutual abra-
sion is prevented : by their flexibility, the con- o
tiguous surfaces are constantly adapted to each ps
other, and the friction diffused equally over the
whole: by their elasticity, the violence of any
shock, which may happen in running, jumping,
&c. is broken and gradually spent; which
must have been extremely pernicious, if the
hard surfaces of bones had been immediately
contiguous. As the course of the cartilaginous
fibres appears calculated chiefly for this last
advantage, to illustrate it, we need only reflect
on the soft undulatory motion of coaches, which
mechanics want to procure by springs, or upon
the difference betwixt riding a chamber-horse
and a real one.” +

* Loc. cit. p. 516,

t+ Hunter, in loco citato. Hunter’s account of
articular cartilage is completely confirmed by M.
De Lasone in a paper in the Mém. de ]’Academie ‘
Royale des Sciences, An 1752. He describes the
cartilage as ‘‘ une multitude des petits filets adossés a
et liés les uns aux autres tous perpendiculaires au
plan de l’os, en un mot parfaitement semblables
par leur structure, ou par leur position alasubstance
emaillée des dents, laquelle n’est composée, comme
on sait, que de filets osseux, posés perpendiculaire-
ment sur le corps de la dent: la comparaison est
des plus exactes.”

ARTICULATION.

b. Synarthrodial cartilage —The cartilages
of synarthrodial articulations are destined in
some degree -to act as bonds of union, as well
as means of separation and for the prevention
of the effects of concussion. They are simply
cartilaginous lamine interposed between the
osseous articular surfaces, very adherent to both,
and adherent likewise by their margins to the
periosteum or ligamentous expansions which
may pass from one bone to another. We find
instances of these cartilages in the sacro-iliac
symphysis, or synchondrosis, as it has been
called from the junction of the bones by carti-
lages;* also in the sutures, where there are
very thin cartilaginous lamine interposed be-
tween the osseous margins. These lamine
will be found to be triangular in their section,
the thin edge or apex being internal, which, as
Meckel observes, may in some degree account
for the earlier obliteration of the sutures on the
internal than on the external surface of the
cranium. ‘These cartilages of sutures are not
strictly permanent ; they disappear with age:
and according to Beclard, hold the midway, as
to frequency of ossification, between permanent
and temporary cartilages.+

The cartilages of the ribs perform in some
degree the office of articular cartilage ; they are
situated between two osseous surfaces; they
form bonds of union, and their elasticity is
eminently essential to the full performance of
the movements of the thorax.

In fishes most of the moveable articulations
are provided with elastic cartilages, which serve
the double purpose of forming bonds of union
as well as of permitting motion by their elasticity.

3. Fibro-cartilage—This remarkable struc-
ture, called by the older anatomists ligamentous
cartilage or cartilaginiform ligament, is made
much use of in the articulations; and it is well
adapted for a means of union, by reason of its
great strength, which it owes to its ligamentous
part, and of its elasticity, for which it is indebted
to its cartilaginous portion. We find fibro-
cartilage to be connected with the joints under
three forms :

a. In the form of laminz, free on both sur-
faces to a greater or less extent, and lined to
the same extent by the synovial membrane re-
flected upon them.{ These are the interarti-

* No one can have failed to notice the peculiar
yellow appearance of the cartilage in the sacro-
iliac articulation. Does that arise from an admix-
ture of the yellow elastic tissue with the pure carti-
lage, by which the elasticity of the latter is in-
creased ?

¢ It is doubted by some whether these cartilagi-
nous laminz can be admitted into the class of arti-
cular cartilages; they being regarded as forming a
nidus for the extension of the fiat cranial bones,

and the sutures being supposed to be useful only for —

_ this purpose, viz. to admit of the growth of these
bones at their margins in a manner analogous to
that of long bones at their extremities. See Soem-
merring de Corp. Hum. Fab. t. i. p. 212, and Gibson
on the use of sutures in the skulls of animals,
Manchester Memoirs, 2d series, vol. i.

t This point, however, is liable to the same
objections as that of the continuity of the synovial
membrane over diarthrodial articular cartilages,

which will be considered in a subsequent part of the
article.

249

cular cartilages or menésci of authors. They
are found in the temporo-maxillary, sterno-
clavicular, and tibio-femoral articulations, some-
times in the acromio-clavicular, between the
bodies of the cervical vertebre in birds, and in
general in those joints where there 1s constant
and extensive motion, and consequently where
the articular surfaces are exposed to consider-
able friction. The principal use of these fibro-
cartilaginous laminz must unquestionably be
to guard against any bad consequences likely
to arise from this continued friction; this is
particularly obvious in the sterno-clavicular
articulation. To increase the depth of an arti-
cular excavation is another object, as appears
from the semilunar cartilages of the knee-joint ;
and moreover, in conjunction with the attain-
ment of these two objects, to ensure in all the
motions of the joint a perfect adaptation of the
articular surfaces to one another, as will appear
obvious to any one who carefully considers the
construction of the temporo-maxillary or even
of the knee-joint.

It will be observed, that I do not include in
the class of interarticular fibro-cartilages, the
lamina which is commonly known by the name
of the triangular cartilage of the wrist joint, as is
done by all the systematic writers I have looked
into ; for, first, it does not appear to me to be
fibro-cartilaginous in its structure; it is purely
cartilaginous ; and, secondly, it is not interar-
ticular, in the sense in which we here use that
term, viz.,as lying between two articular surfaces.
This lamina seems to be merely an extension of
the cartilaginous incrustation of the inferior ex-
tremity of the radius, which completes the ar-
ticular surface for the reception of the first row
of carpal bones. The scaphoides and lunare are
provided for by the radius; but as the ulna
could not be brought into the composition of
the wrist-joint without interfering with the
motions of the inferior radio-ulnar articulation, a
structure such as the triangular cartilage, was
necessary—one which would present a sufficient
opposing surface to the articular portion of the
os cuneiforme, and which would not impede or
obstruct the necessary motions of the joint
between the radius and ulna.

In the cases of the temporo-maxillary and
sterno-clavicular articulations, these fibro-carti-
lages form, in general, complete septa between
two portions of the joint: so that there are then
two synovial sacs; but sometimes there is a per-
foration in the centre of the fibro-cartilage.

b. The second class of articular fibro-carti-
lages consists of those which Meckel designates
jibro-cartilages of circumference, or cylindrical
Sibro-cartilages. They form fibro-cartilaginous
brims to certain articular excavations; they are
triangular in their section, attached by their
basis to the osseous margin of the articular
cavity, and free at their apices, lined by synovial
membrane on the whole of one side, and a
great part of the other. They are to be found
only in two joints, namely, on the margin of
the acetabulum in the hip-joint, and on the
edge of the glenoid cavity in the articulation of
the shoulder ; in the former, this fibro-cartilage
is much larger and stronger, and is evidently

250

intended to obviate the ill consequences which
must have resulted from the violent application
of the neck of the femur against the bony
margin of the acetabulum: for, where the
margin of that cavity is ligamentous, viz., at
the notch on its inner side, this fibro-cartilage
does not exist.

c. The most remarkable and beautiful variety
of this structure belongs to the third class. It
consists of fibro-cartilaginous lamine, generally
of considerable thickness, which intervene be-
tween two bones and adhere intimately to each.
Examples of it are to be found between the
bodies of the vertebrae, (intervertebral sub-
stance)—between the pieces of the sacrum in
early life—between the sacrum and coccyx,
and between the pieces of the latter—also, be-
tween the ossa pubis at the joint called the
symphysis pubis. In this class of fibro-car-
tilages too, we may place that which is situ-
ated between the scaphoid and lunar bones in
the carpus.

It is evident that these fibro-cartilages are
useful, not only as very powerful bonds of
union, but also as elastic cushions placed be-
tween the bones to prevent the concussion
which must necessarily result, did the unyield-
ing bony surfaces come together with any de-
gree of force... No where is this so beautifully
exhibited as in that chain of bones which
forms the spinal column in the mammiferous
vertebrata, the strength and flexibility of
which result from the fibro-cartilaginous dises,
which, placed between the bodies of the ver-
tebre, are commonly called intervertebral car-
tilages.

As to the structure of articular fibro-cartilage,
we can distinctly observe, without any process
of dissection, that it is compounded of fibrous
tissue as well as of cartilage. As these fibro-
cartilages generally assume more or less of the
circular form, we find that the fibrous tissue is
most abundant towards the circumference, and
that the cartilage is most manifest at the centre.
In the intervertebral substance, the fibrous
tissue is arranged in concentric lamine, placed
vertically behind one another. Each lamina is
composed of a series of interlacing fibres, which
have intervals between them; these intervals,
as well as those between the lamina, are filled
by cartilaginous tissue; towards the centre the
fibrous lamine diminish in number, the inter-
vals become large, and at length the fibrous
tissue disappears in toto; hence the gradually
diminishing density towards the centre, which
characterises the intervertebral substance. In
fishes, there is such a diminution of density,
that the central part is fluid, but here the sur-
faces of the vertebra are excavated, not plane
as in the mammiferous vertebrata, and the cha-
racter of the articulation is thereby materially
altered. The incompressible central fluid forms
a ball, round which the cup-like excavations of
the vertebre play, while the fibro-cartilage at
the circumference is made available in the la-
teral motions of the spine.

Of the three varieties of fibro-cartilage above
enumerated, the menisci possess the most car-
tilage in their structure, and the circumferential

ARTICULATION. Ca

7
mP

fibro-cartilages the greatest quantity of fibrous —
tissue. an SE

‘ -
_

It may be questioned whether that peculiar
structure which intervenes between the base of
the skull and the condyle of the lower jaw in
the whalebone whale, ( balena mysticetus ) be-
longs to the class of fibro-cartilages, although
it seems to bear a nearer resemblance to that =
than to any of the other structures employed in
the composition of joints. The following is
Sir Everard Home’s description of it.* “ Be- —
tween the condyles of the lower jaw and the
basis of the skull is interposed a thick sub-
stance, made up of a network of ligamentous
fibres, the interstices of which are filled with
oil, so that the parts move readily on each other.
The condyles have neither a smooth surface
nor a cartilaginous covering, but are firmly
attached to the intermediate substance, which
in this animal is a substitute for the double
joint met with in the quadruped, and is cer-
tainly a substitute of the most simple kind.”

4. Ligament.—The term ligament, as it is
used by systematic writers on descriptive ana-
tomy, is by no means confined to portions of
the “ fibrous system” of Bichat, although all
the articular ligaments (properly so called) be-
long to that system. Weitbrecht comprehends
under this term all fibrous structures in and
about joints, including the fibrous sheaths of
tendons, and also all membranous folds, which
are in any way concerned in maintaining soft
parts or viscera in proprio situ. I apprehend,
however, that a better definition of articular
ligament could not be given than the following,
which is that of Weitbrecht, the words printed
in italics being added,—“ Ligamentum est par-
ticula corporis, plerumque albicans, interdum
Jlava, ex fibris flexilibus, interdum elasticis,
plerumque parallele concretis, in substantiam
tenacem fibrosam, ruptioni fortiter resistentem,
et solidam compacta, eum in finem creata ut
due pluresve partes que alias divulse per se
subsisterent, adunentur atque in situ respectivo
determinentur.”+ Most of the articular liga-
ments are employed to unite the bones which
compose a joint; theyalso will be found uniting
some of the interarticular cartilages within
joints, or passing from one part of a bone to
another (forming the “‘ mixed” class of liga-
ments of Beclard); and such is the vagueness
with which names are applied in descriptive
anatomy, that folds of the synovial membrane
often receive this appellation without the least
title to it.

Articular ligaments are divisible as regards —
their forms into two species, the capsular and
the funicular or fascicular.{

Capsular ligaments are generally cylindrical —
in shape, or rather barrel-shaped, being wider —
in the centre than at the extremes. Each ex- —
tremity envelopes one of the bones that enters
into the formation of the joint, so that the arti-—
cular cavity is completely surrounded by and
enclosed within the ligamentous capsule. Liga-—

* Comp. Anat. vol. i. p. 83.
+ Syndesmologia, § 5.
t Beclard, Anat. Gen.

ARTICULATION.

ments of this kind are composed of fibres
which are closely interwoven with each other,
and they sometimes receive accessions from
bundles of ligamentous fibres coming from
neighbouring bony prominences (these fibres
being generally called accessory ligaments. )
Capsular ligaments are not calculated to re-
strict the extent or direction of motion be-
tween the bones which they surround, and
we consequently find them only in that
kind of joint which admits of motion in all
directions, viz. the enarthrosis or ball-and-
socket joint, of which the only examples in
the human subject are to be met with in the
hip and shoulder. The internal or articular
surface of capsular ligaments is to a great
extent lined by one lamina of the synovial
membrane, which is reflected upon it from the
articular portion of the most moveable of the
bones which form the joint.

Funicular ligaments are found in the form of
rounded cords or flattened bands: they exist
generally on the exterior of joints, very rarely
on the interior, and always externally to the sac
of the synovial membrane. They pass from
bone to bone, adherent sometimes to the syno-
vial membrane of the articulation, sometimes to
the intervening fibro-cartilage. In ginglymoid
joints they are always placed on the sides, and
are called dateral ligaments ; sometimes they
cross or decussate with each other, whence the
appellation crucial, and sometimes a ligament
of this class assumes a nearly circular course,
and forms a greater or smaller portion of the
circumference of a circle, the remainder of the
round being completed by the bone into which
the extremities of the ligament are fixed; a
ring is in this way produced within which the
head, or a special process of another bone, is
enclosed, as is seen to be the case particularly
with the head of the radius in the superior
radio-ulnar articulation, and with the processus
dentatus in the joint between the axis and
atlas: the ligament in such instances is called
coronary. When a ligament is concealed in
the interior of a joint, although situated exter-
nally to the synovial sac, or, to speak more
correctly, in the space between the articular
surfaces, it is called an internal ligament, e. g.
the ligamentum teres of the hip-joint, the mu-
cous ligament of the knee, or the transverse
ligament of the same articulation.

Elastic ligament—Hitherto we have been
examining ligamentous structure, one of whose
most prominent characteristics is the want of
elasticity ; but we now come to a kind of liga-
ment which forms a most valuable constituent
in the mechanism of some joints, and is emi-
nently distinguished for the great elasticity which
it possesses. It differs from ordinary ligament
by its yellow colour, (whence the French ap-
pellation ¢issw jaune, ) as well as by its elasti-
city. We find it in the human subject most
developed in the ligamenta subflava of the
vertebre. In joints, as elsewhere, this tissue
is employed to restore to the position of quie-
scence, parts which have been previously acted
upon by muscular contraction. John Hunter

251

fully appreciated the value and utility of this
structure in supplying the place of muscle, with
less expense of exertion to the economy, and
assigned it a place in the arrangement of his
museum.* The thyro-hyoid and crico-thyroid
ligaments in man are formed of this struc-
ture.

5. Synovial membrane.—The articular syno-
vial inembranes, (by the older anatomists called,
and confounded with, the capsular ligaments,)
like all others, possess in common with serous
membranes the form of a sac shut in all points ;
they line the whole interior of the joints, and
secrete from their internal surface a peculiar
fluid, obviously destined for the lubrication of
the articular surfaces. These membranes are
remarkable for their great tenuity; they are
transparent; in a state of inflammation, their
vascularity, which is imperceptible during
health, becomes very apparent by the general
redness which the membrane assumes; and
their internal or secreting surface is easily dis-
tinguished from the external, by contrasting the
smooth and glistening appearance of the former
with the roughness which the latter receives
from the cellular tissue and ligamentous fibres
which adhere to it. The internal surface of
the membrane is sometimes thrown into folds
with fringe-like margins, which project into
its cavity or sac. These folds contain more
or less of cellular tissue and a number of
pellets of fat, which being supplied with ves-
sels, the margin of the synovial fringe is some-
times tinged red. These folds are compared,
and certainly with much justice, to the epi-
ed folds of the abdominal serous mem-

ranes, more especially to the appendices
epiploice of the great intestine. Beclard sup-
poses that these fringes are specially the seat of
the synovial secretion, which being perspiratory
likewise takes place, though less abundantly
and manifestly, from the rest of the synovial
surface. The best examples of these folds
occur in the knee and hip-joints, in the former
of which they have been absurdly called alar
ligaments.

Some idea may be formed of the manner in
which the synovial membrane is related to the
other articular structures by examining the an-
nexed figure, (fig. 111,) representing a vertical
section of the knee-joint. The cut margin of
the synovial membrane is indicated by a, which
after lining the posterior surface of the patella
and ligamentum patellz, is reflected upon the
condyles of the femur, whence it is carried in
front of the crucial ligaments to line the arti-
cular surface of the head of the tibia, and from
that is again reflected upwards, and is con-
tinuous with the portion lining the posterior car-
tilaginous surface of the patella. This descrip-
tion is founded on the opinion, which I believe
to be correct, that the analogy between serous
and synovial membranes is accurate, in so far
as their possessing in common the form of
shut sacs is concerned. On this subject, how-

Vide Home’s Lect. on Comp. Anat. Lect. i.
vol. i.

252 ARTICULATION.

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ever, anatomists are by no means likely ever
to be unanimous, because of the difficulty or
impossibility of tracing by the ordinary me-
thods of dissection the synovial membrane
over the articular cartilages. The continuity of
this membrane over the cartilage was first
distinctly announced and described by Dr.
W. Hunter, in the paper to which we have
already referred in the Philosophical Trans-
actions: after him Soemmerring described it,
and still later Bichat, who insisted more par-
ticularly on its analogy with serous mem-
branes. Bichat’s description has been followed
by Meckel, Beclard, and most of the anato-
mists of modern times; but its accuracy has
been called in question by Cruveilhier,*
Gordon,t+ Magendie,{ Blandin,§ and more re-
cently by Gendrin|| and Velpeau.{

The advocates for the continuity of the syno-
vial membranes over the diarthrodial cartilages,
found their opinion on the following facts :—
1. Synovial membranes elsewhere, lining ten-
dinous sheaths or bursze mucose, are distinctly
and obviously shut sacs. 2. We do not find

* Observations sur les Cartilages diarthrodiaux.
Arch. Gen, de Méd. tom. iv. p. 161.

+ Gordon says, ‘‘ the continuation of the syno-
vial membranes over the surface of articulating
cartilages is, I am convinced from a number of ex~-
periments, altogether an anatomical refinement.” —
System of Human Anatomy, p. 261.

¢ Compend. of Physiology, y Milligan, p. 450.

§ Additions 4 Bichat, par Beclard et Blandin,

. 345.
F Hist. Anat. des Inflam. t. i. P: 60.
Anat. Chir. ed. 2de, t. i, p. 176.

cartilage to present the smooth and polished
aspect exhibited by the articular surfaces, ex-
cepting where it is connected with synovial
membrane, as it evidently is to at least a cer-
tain extent in the moveable articulations. 3. If
by an oblique cut we raise a slice from an arti-
cular cartilage, and turn it back so as to rupture
it at its base, we shall find it still retained in
connexion with the rest of the cartilage by a
thin pellicle, which seems to have all the cha-
racters of synovial membrane. A similar mem-
brane may be seen by sawing a bone vertically
down to the cartilage, and then breaking the
cartilage by forcibly separating the segments.
4. Some observers state that they have seen the
redness of inflammation affecting the synovial
membranes prolonged over the cartilage,* but
becoming gradually less marked towards the
centre—(this,I must confess, I have never seen).
5. Bands of adhesion are also said to have been
met with in some cases of chronic inflammation
of the synovial membrane, passing from the ar-
ticular surfaces, as well as from other parts of
the interior of the joint. 6. In that peculiar
disease of the synovial membrane described by
Brodie, the pulpy substance has been seen on the
articular cartilages, as well as on the menisci.

On the other hand, the opponents of this
Opinion deny: 1, that the membrane demon-
strable by slicing the cartilage in the way above
described, is any thing else than a very thin
lamina of cartilage; 2, they say that by even
the most successful injection the fluid cannot
be made to pass beyond the margin of the car-
tilage; 3, they assert that inflammation always
stops abruptly at the circumference of the car-
tilage ; 4, and that if a synovial membrane did
exist on the free surface of the cartilage, there
would take place a continual exhalation of sy-
novia from the articular surface, contrary to what
was found to be the case in an experiment tried
by Cruveilhier: synovia was freely exhaled from
the membrane lining the ligaments, and after
having been wiped off reappeared with rapidity ;
but not so over the articular cartilage, the sur-
face of which became quite dry. {

Cruveilhier, however, relates a case which in
some degree invalidates his own conclusions ;
it was one in which fungous granulations sprang
from the articular surfaces of the femur and
tibia in the knee-joint, and by their adhesion
produced anchylosis of the joint: this fact Cru-
veilhier § very candidly expresses his inability

* I am uncertain whether the fourth case related
by Sir B. Brodie in the last edition of his work on
the joints, may not be regarded as affording an in-
stance of this. In the account of the post-mortem
examination it is said, ‘‘ The synovial membrane
was everywhere of a red colour, asif stained by
the secretion,” p. 15. Beclard, whose powers
and accuracy of observation few will be disposed
to question, speaks with the confidence of one who
had seen this extension of the vessels over the car-
tilage.—Anat. Gen. p. 214.

+ Vide the 17th, 18th, 19th, 21st, and 22d cases
recorded in Sir B. Brodie’s work.

¢ Cruveilhier, loc cit.

§ He confesses, ‘‘ ma conviction n’est pas cepen-
dant pleine et entiére.”

wre Ae .
Ee

i.

ARTICULATION.

to explain without admitting either the exist-
ence of the synovial membrane, or the organi-
zation* of the cartilages. Velpeau,t too, al-
though he asserts that the synovial membrane
“< terminates at the circumference of the carti-
lages,” furnishes us with an argument in oppo-
sition to his own views: namely, that no appre-
ciable line of demarcation can be detected
indicating where the synovial membrane
ceases. ‘ Viewed in this way,” he says, “ the
synovial apparatus consists of surfaces, mem-
branes, and glandular folds, between which
there exists not the least interruption, and
the use of which is to isolate the interior of
the joint from the tissues which surround it.”

It will appear then sufficiently evident that
the weight ofa argument preponderates in favour
of the doctrine that the synovial membranes
line the articular surface of the cartilages, and
that maintains their analogy with the serous
membranes, an analogy which receives the
strongest support from the physical properties
of the synovial membrane, from its obvious
functions during health, and from the diseases
with which it is affected; and I apprehend,
that nothing tends more fully to establish iden-
tity or similarity in the nature of two mem-
branes, than the fact of a close resemblance
between their morbid conditions. We ma
add, what was long ago remarked by W.
Hunter, that this question as to the continuity
of the synovial membrane on the cartilages is
very similar to that as to the continuity of
the conjunctiva over the cornea of the eye;
the affirmation of which latter question, Gordon
considers equally an anatomical refinement as
that of the former.

Velpeau { ascribes much importance to the
dense and fine cellular tissue which is sub-
jacent to the synovial membrane and is ana-
logous to the subserous cellular tissue else-
where. This would appear to be the seat of
the vessels which in a state of inflammation
give rise to the red colour of the synovial mem-
brane. He particularly alludes to it as afford-
ing a clue by which the formation of loose
cartilaginous bodies in joints can be explained ;
these he supposes to originate in sanguineous
effusions into this tissue, which subsequently
become indurated and cartilaginous, and push
the synovial membrane before them into the
cavity of the joint. It will be remembered by
many readers that this opinion is very similar
to that of John Hunter regarding the origin of
these bodies. §

Allusion has already been made to the fatt
bodies which are found in connexion wit

* This is a bad word ; we cannot deny the orga-
nization of cartilages, however we may deny that
they are supplied with red blood. It has been said,
I know not with what authenticity, that cartilages
have become yellow in jaundice.

t Loc. cit. pp. 172 and 174. He expresses his
opinion much more decidedly in the art. ARTICU-
LATIONS, MALADIEs DES. Dict. de Med.

t Loc. cit. v. i. p. 173.

§ See Home’s Paper, in Trans. of a Soc. for the
nen of Med. and Chirurg. Knowledge,
vel. f

253

most of the joints, and in general lying behind
the synovial fringes formerly described. These
fatty pellets were supposed by Clopton Havers*
to be the agents of the synovial secretion, and,
in consequence, have obtained much celebrity
under the title of Haversian glands.+ The
opinion of Havers and his followers as to their
glandular nature was successfully combated by
Bichat, who proved that they were merely
composed of adipose substance, and in no
way concerned in the function of synovial
secretion : for Ist, the secretion of synovia takes
place where no such bodies exist, as in almost
all the burs mucosz, and tendinous sheaths;
and 2d, these bodies have no trace of glan
dular structure, nor are they provided with any
thing resembling an excretory duct; whilst, on
the other hand, they possess all the properties
of fat.

The synovial sac is lubricated by the sy-
novia, also called unguen articulare, arungia
articularis. How is this secreted? We believe
it to be a perspiratory secretion precisely similar
to that of the serum from serous membranes.
Its formation cannot be imputed to a com-
bination of the serosity of the blood with the
fat, nor to the transudation of the marrow through
the extremities of the bones, nor, with Desault,
to a sweating from all the parts which enter
into the composition of the articulation, inas-
much as the chemical analysis of synovia
proves that it is essentially different from any
oily fluid, and does not contain a trace either
of elaine and stearine.

In addition to the structures already named
as entering intrinsically into the formation of
joints, we find that the tendons and muscles,
which lie in the immediate vicinity of or which
surround the joints, contribute much to their
Strength and security. In joints of the hinge
kind we generally see the anterior and poste-
rior parts protected more or less by the tendons
of muscles, and even by muscles themselves
passing from one segment of a limb to an-
other, and here it frequently happens that the
tendon is bound down on the bones which form
the member, by a fibrous expansion of great
strength, lined by a synovial membrane of the
same characters as the articular, but adapted in
its form to the osseo-fibrous canal in which the
tendon is placed, e.g. the tendons of the fingers.
The protection and strength afforded by mus-
cles is particularly evinced in the case of
the shoulder-joint, where the capsular ligament
is closely embraced by four muscles, whose
tendons become identified with the fibrous
capsule as they go to be inserted into the bone.
A muscular capsule, as it were, is thus provided
for this joint, by which the bones are main-
tained much more firmly and powerfully in
apposition than were they kept together by
an uncontractile ligamentous capsule alone ;
hence the elongation of the arm which ap-

* Osteologia Nova: Lond. 1691.

+ Weitbrecht called these fatty bodies, “ Adi-
poso-glandulos#;” and Cowper, ‘‘ mucilaginous
glands.” See them figured in Monro’s work on the
Bursz, Tab. viii.

254

pears as a consequence of paralysis, and hence
also the greater liability to luxation which
exists in a debilitated state of the system.
Articular or capsular muscles thus placed, have
also the effect, as it is said, of preventing
the pinching of the capsule or synovial mem-
brane between the articular extremities of the
bones in the different motions of the joint.

The joints are very generally copiously sup-
plied with blood, and are remarkable for the
arterial anastomoses which take place around
them. The best examples of these are met with
in each of the joints of the extremities. ‘The
parts supplied with blood are the synovial
membranes, the ligaments, the fat, and the extre-
mities of the bones; but the cartilages cer-
tainly do not receive vessels carrying red
blood: [ believe there is no fact in anatomy,
more generally admitted or better determined
than this. The vascular ramifications which
proceed from these vessels may be seen, par-
ticularly in young subjects, advancing in the
subsynovial cellular tissue, and forming a vas-
cular net-work there, as far as the margin of the
articular cartilage where they stop abruptly ;
this is what W. Hunter described under the
name of circulus articuli vasculosus.

Of the forms and classification of the arti-
culations—It is not difficult, by passing in
review the various motions which take place
between any two segments of a limb, to form
an idea, @ priori, as to the kinds and shapes
of the articulations by which these segments
will be united; it is only necessary not to lose
sight of the fact, that in the construction of a
joint regard is had not to its mobility alone,
but to its security, its durability, and the safety
of the neighbouring parts. We may expect
to find joints varying in the degree of motion,
from the slightest perceptible quantity, to the
freest that is compatible with the maintenance
of the segments in their proper relation with
each other, and also in ertent of motion, from
that which is so slight as to admit of almost
no appreciable change in the position of the
parts, to that which allows of the most ample
variety of relation between the segments,
consistent with the integrity of the articula-
tion.

It will appear, then, that the most simple
kind of articulation is that by which two parts
are so united as that the slightest appreciable
degree of motion only shall exist between them.
This constitutes the first great division of joints
—the Synarthrosis (ovr, cum, and aeQeoy, urti-
culus )—where the parts are continuous, 7. e.
not separated from each other by an intervening
synovial cavity. Some anatomists consider all
synarthrodial joints to be immoveable; which,
although not far from the truth, cannot be said
to be strictly accurate. Had immobility been
the object to be obtained, I imagine that that
might have been more effectually accomplished
by the fusion of the extremities of the segments
together, as in anchylosis.

In the second class of joints, motion is
enjoyed freely and fully: this class is designated
by the term Diarthrosis (dsa, per, and aebgov):

ARTICULATION, |
the segments are interrupted completely in —

their continuity; the extremities of the bones
can only be said to be contiguous. ut

Synarthrosis.—The general characters of the
articulations belonging to this class are, 1.

=

that they are very limited in their motion,

insomuch as to be considered by some as im-
moveable; 2. that their surfaces are continuous,
i.e. without the intervention of a synovial
cavity, but with that of some structure different
from bone. The following varieties may be
noticed among synarthrodial articulations.

a. Suture (Germ. Nath or Naht. Com-
missura cranii, Vesal.).—When the margins of
two bones exhibit a series of processes and
indentations (dovetailing) which are received
and receive reciprocally, with a very thin car-
tilaginous lamina interposed, this is the ordi-
nary kind of suture, sufura vera, of which
three kinds are distinguished : swtura dentata,
where the processes are long and dentiform, as
in the interparietal suture of the human skull;
sutura serrata, when the indentations and
processes are small and fine like the teeth
of a saw, as in the suture between the two por-
tions of the frontal bone; sutura limbosa, when
there is along with the dentated margins a
degree of bevelling of one, so that one bone
rests on the other, as in the occipito-parietal
suture.

When two bones are in juxta-position by
plane but rough surfaces, the articulation is
likewise said to be by suture, and this is the
false suture, sutura notha, of which there are
two kinds: sutura squamosa, where the be-
velled edge of one bone overlaps and rests
upon the other, as in the temporo-parietal
suture, and harmonia (agw, adapto), where
there is simple apposition: this last kind of
articulation is met with, as Bichat* observes,
wherever the mechanism of the parts is alone
sufficient to maintain them in their proper
situation, as may be seen in the union of most
of the bones of the face.

It is in the,articulation of the bones of the
skull and face of animals, as has been already
noticed, that we see the best examples of su-
tures. In the chelonian reptiles, as the tortoise,
the bodies, laminz, and spinous processes of the
vertebre are united by suture, and the same
mode of articulation unites the elements of
the sternum of the land-tortoise to each other.
The bones of the head of birds and fishes
are united chiefly by the harmonic and squamous
sutures. In the lateral parts of the heads of
fishes, and in the opercula of their gills, as
between the opercular and subopercular bones,
there is a species of articulation, most re-
sembling the squamous suture, but differing
from it in admitting a considerable latitude of
motion by which these bones can glide on

one another.{ To descend still lower in_ the

scale, we may observe a mode of joining very

similar to suture, between the tubercular and

* Anat. Gen. t. iii. p. 63.

+ See Grant’s Comp. Anat. p. 83, fig. 48.

¢ Cuvier, Lecons d’Anat. Comp t.. i. p. 125,

ae. *

T!
“iS

ARTICULATION.

ambulacral plates which form the shell-like
covering of the echinida.*

The sutures have the peculiarity of a con-
siderable tendency to become obliterated by
age, the intervening cartilage being ossified ;
it rarely happens that the sutures are all ma-
nifest in a human skull past fifty years of age,
and sometimes the obliteration takes place at
a much earlier period. The frontal suture is
by no means permanent; it is not often found
at puberty. In birds and fishes this tendency
to the obliteration of the sutures is particularly
manifest.

b. Schindylesis (cxvdvanoss, fissio, ox slu,
diffindo ).—This form of articulation is where
a thin plate of bone is received into a space
or cleft formed by the separation of two lamin
of another, as is seen in the insertion of the
azygos process of the sphenoid bone into the fis-
sure on the superior margin of the vomer ; and
in the articulation of the lacrymal bone with the
ascending process of the superior maxillary.

c. Gomphosis (youdos, clavus. Clavatio,
conclavatio)—When a bone is inserted into
a cavity in another, as a nail is driven into a
board, or as a tree is inserted into the earth
by its roots, the articulation is by gomphosis.
The only example we have of it in the human
subject or in quadrupeds is in the insertion
of the teeth into the alveoli. In the weapon
of offence of the saw-fish we find also an
example in the manner in which the strong
osseous spines are inserted like teeth into its
lateral edges. Cuvier mentions a variety of
gomphosis, the only modification of the above:
it is where a bony process grows from the
bottom of the recipient cavity, and is inserted

into a cavity in the base of the received bone

“fills up the cavity of the nail.

or hard part. This is the mode of articulation
of the nails with the ungueal phalanges in
animals of the cat kind; the nail is received
into an osseous sheath, from the bottom of
which the body of the phalanx projects and
A similar pivot
grows from the bottom of the alveoli, into
which the long canine teeth of the walrus are
inserted.

d. Amphiarthrosis (auQs, utrinque, aebeov,
articulus, i.e. a mixed form of- articulation.
Articulatio dubia, Bartholin. Synarthrosis diar-
throdica ).—This is a form of articulation where

two plane or mutually adapted surfaces are held
together by a cartilaginous or fibro-cartilaginous
lamina of considerable thickness, as well as

‘by external ligaments. In virtue of the elasti-
city of the interposed cartilaginous or fibro-
cartilaginous lamina, the amphiarthrosis pos-
sesses a manifest, although certainly a very

limited degree of motion, and hence most

systematic writers class it with the diarthrodial
articulations. To me it appears much more
consistent to place it among the synarthrodial
joints, for, 1. its anatomical characters agree
precisely with those of synarthrosis; 2. the

surfaces in amphiarthrosis being continuous, it

would make an exception in diarthrosis were

* Meckel, Anat. Comp. (Fr. transl.) t. ii. p. 43,

255

we to place it there; and, 3. its degree of
motion is greater than that of suture, only
because of the greater development of the in-
terosseous substance. These points of similarity
led some anatomists to call it Diarthrosis syn-
arthrodica ; for the reasons above stated, as
well as because it has one point of resemblance
to diarthrosis in its greater latitude of motion,
I propose the appellation Synarthrosis diar-
throdica.

The examples of this form of joint in the
human body are the articulation between the
bodies of the vertebre, that between the two
ossa pubis at what is called the symphysis, and
that between the ilium and sacrum. We
may also, I think, place here the articulation
of the ribs with the sternum by means of the
costal cartilages.* The bodies of the vertebra
in most of the mammalia are articulated in
the same way; so are they in fishes also; but
in these last there is a peculiarity already re-
ferred to, which increases the degree of motion
of which the joint is susceptible.t Like the
sutures, the amphiarthrosis is liable to become
obliterated by age, and from the same cause,
namely, the ossification of the interosseous la-
mina. ‘This is very common in the costo-sternal
joints, less so in the interpubic, and still more
rare in the inter-vertebral and sacro-iliac.

Diarthrosis.—Evident mobility is the dis-
tinguishing characteristic of this class of joints;
the articular surfaces are contiguous, each co-
vered by a lamina of cartilage (diarthrodial
cartilage), having a synovial sac, and in
some cases two synovial sacs interposed,
which are separated by a meniscus. The in-
tegrity of the articulation is maintained by liga-
ments which pass from the one bone to the
other. Their mechanism is much more com-
plicated than that of synarthrodial joints, being
intended not only for security, but also to give
a certain direction to the motions of which
they are the centre.

Before proceeding to the enumeration of the
varieties of joints that come under this head, it
will not be amiss to describe briefly the various
motions which may take place between any two
segments of a limb, and which it is the object
of these joints to admit of. It is obvious that
the most simple kind of motion which can exist
between two plane or contiguous surfaces, is that
of gliding: one surface glides over the other,
limited by the ligaments which extend be-
tween the bones. This motion, however, is not
confined to plane surfaces, it may exist evidently
between contiguous surfaces whatever their form.
When two segments of a limb, placed in a
direct line or nearly so, can be brought to form

* It may be objected to this arrangement that
at the sternal extremity of each cartilage there is
a synovial membrane between it and the sternal
depression. All anatomists agree in denying its
existence at the articulation of the first cartilage,
and all admit the great difficulty of fully demon-
strating its existence in the others. For my own
part I do not believe that it exists in any.

+ The articulation of the lower jaw in the whale-
bone whale, above referred to, is a joint of this
kind,

256 ARTICULATION.

an angle with each other, the motion 1s that of
flexion, the restoration to the direct line is ev-
tension. These two motions belong to what
Bichat calls limited opposition ; the flexion and
extension of the fore-arm on the arm illustrate
it. Sometimes a motion of this kind takes
place in four directions, indicated by two lines
which cut at right angles. This is best under-
stood by a reference to the motions which take
place at the hip-joint: there it will be seen
that the thigh-bone may be brought forward so
as to form an angle with the trunk, flerion—or
it may be restored, extension ; it may be sepa-
rated from the middle line of the body so as to
form an angle with the lateral surface of the
trunk, abduction—or it may be restored and
made to approximate the middle line, adduc-
tion. Bichat terms this “ opposition vague.” It
is evident that a joint, which is_ suscepti-
ble of these four motions, may also move in
directions intermediate to them. When these
motions are performed rapidly, one after the
other, it appears as one continuous motion, in
which the distal extremity of the bone describes
a circle indicating the base of a cone whose
apex is the articular extremity moving in the
joint ; this motion is called circumduction.

Rotation is simply the revolving of a bone
round its axis. It is important to bear this
definition in mind : through losing sight of it
many anatomists have attributed rotation to a
joint which really does not possess it.

The varieties of the diarthrodial joint are as
follows :

a. Arthrodia (articulatio plana or plani-
JSormis.)—In this species the surfaces are plane
or one is slightly concave, and the other slightly
convex: the motion is that of gliding, limited in
extent and direction only by the ligaments of
the joint or by some process or processes con-
nected with the bones. The examples in man
are, the articular processes of the vertebra, the
radio-carpal, carpal, carpo-metacarpal, infe-
rior radio-ulnar, superior tibio-fibular, tarsal
and tarso-metatarsal, temporo-maxillary, acro-
mio-clavicular and _ sterno-clavicular joints.
This last articulation and the wrist-joint possess
a greater latitude of motion than the others ;
the former, in consequence of the shape of its
articular surfaces: each surface is convex in
one diameter and concave in the other, so that
the gliding that takes place in this joint is in
the direction of the long and short diameters,
which intersect each other at right angles. It
is capable, therefore, of vague opposition in
those lines, but certainly not in the interme-
diate directions, the nature of the surfaces being
calculated to prevent this. The wrist owes
its mobility to the laxity of its ligaments, which
permit it to move as well in its transverse as in
its antero-posterior diameters, as also in the in-
termediate directions; it consequently admits
of vague opposition and circumduction. The
articulation of the metacarpal bone of the thumb
with the trapezium, is also an arthrodia very
similar to the sterno-clavicular, but with a
greater degree of motion. Arthrodial joints are
generally provided with ligaments, placed at the

extremities of the lines in the direction of
which the gliding motion takes place.

b. Enarthrosis( diarthrosis orbicularis—ball-
and-socket joint. )—This is a highly developed
arthrodia. The convex surface assumes a glo-
bular shape, and the concavity is so much
deepened as to be cup-like, hence the appella-
tion ball and socket. The ball is kept in appo-
sition with the socket by means of a capsular
ligament, which is sometimes strengthened by
accessory fibres at certain parts that are likely
to be much pressed upon. The-best example
of enarthrosis is the hip-joint, and next to it the
shoulder: in the latter the cavity is but imper-
fectly developed. All the quadrupeds have
their shoulder and hip joints on this construc-
tion, and the same common_plan is observed in
the vertebrata generally whose extremities are
developed. In birds and reptiles the bodies, of
the vertebree are articulated by enarthrosis, and
the solid calcareous spines on the external
surface of the shells of echinida are adapted to
round tubercles on which they move, thus ex-
hibiting a very complete form of enarthrosis.*

This species of joint is capable of motion of
all kinds, opposition and circumduction being
the most perfect, but rotation limited. Indeed
what is called rotation at the hip-joint, is
effected by a gliding of the head of the femur
from before backwards, and vice versa in the
acetabulum ; it is not a rotation of the head
and neck, but of the shaft of the femur.

c. Ginglymus (yyyAvpos, cardo, articulatio
cardiniformis, articulation en charniere, en ge-
nou, hinge~joint.)—The articular surfaces in
the hinge-joint are marked with elevations
and depressions which exactly fit into each
other, so as to restrict motion in all but one
line of direction. They are always provided
with strong lateral ligaments, which are the
chief bonds of union of the articular surfaces.

The elbow and ankle joints in man are per-
fect ginglymi; the knee also belongs to this
class, but is by no means a perfect specimen,
for in a certain position of the bones of this
joint, the ligaments are so relaxed as to allow a
slight rotation to take place. The phalangeal
articulations, both of the fingers and toes, are
ginglymi. This form of joint is most exten-
sively employed among the lower animals. In
quadrupeds, most of the joints of the extremi-
ties come under this head. In amphibia and
reptiles, too, there are many examples of the
hinge-joint. The bivalve shells of conchiferous
mollusca are united by a very perfect hinge,
and a great number of the joints of crustacea
and insects are of this form.

The true ginglymus is only susceptible of
limited opposition: hence the knee-joint can-
not be regarded as a perfect example ; in fact,
in the perfect ginglymus there is every possible
provision against lateral motion. _

d. Diarthrosis rotatorius (commissura tro-
choides. )—A pivot and a ring constitute the
mechanism of this form of joimt. The ring is

* Vide fig. 9 in Grant’s Comp, Anat. p.21. See
also the article ECHINODERMATA.,

ra
¥
i

— <=.

ASPHYXIA.

generally formed partly of bone and partly of
ligament, and sometimes moves on the pivot,
sometimes the pivot moves in it. The motion
is evidently confined to rotation, the axis of
which is the axis of the pivot.

In the human subject the best example of
this articulation is that between the atlas and
odontoid process of the axis or vertebra dentata.
The ring is formed by a portion of the anterior
arch of the atlas, completed behind by a trans-
verse ligament. Here the atlas rotates round
the odontoid process, which is the axis of mo-
tion. Another example is the superior radio-
ulnar articulation : here the ring is formed one-
fourth by bone, namely the lesser sigmoid cavity
of the ulna, and the remaining three-fourths by
the round ligament called the coronary ligament
of the radius. In this case there is rotation as
perfect as in that just mentioned, but the head
of the radius rolls in the ring, and the axis of
motion is the axis of the head and neck of the
bone. Some anatomists consider this joint a
species of ginglymus, which they designate
lateral.

The terms Symphysis, Synchondrosis, Syn-
neurosis, Syssarcosis, Meningosis, have been
employed by anatomists to designate certain
kinds of articulation, chiefly in reference to the
nature of the connecting media. Symphysis,
although originally employed with great extent
of meaning, seems to have been in later days
applied exclusively to denote the articulations
of the pelvis, which we have classed under
Amphiarthrosis. I pass over the other terms,
because they ought to be discarded from use,
as only tending to encumber a vocabulary
already too much crowded with difficult and
unnecessary terms. :

The descriptive anatomy of the several joints
will be found under the heads—Awnxtz, Cra-
NtumM, Exsow, Face, Foor, Hann, Hip,
Kner, Petvis, Rapio-utnar, SHoucper,
Spine, Temroro-MaxiLiary, T1510- FrBvu-
Lar, Wrist, and the morbid anatomy under
the head Jornr.

BIBLIOGRAPHY.—Havers, Osteologia nova, 8vo.
Lond.1691. Saltzmann, De Articulationibus Artuum,
Argent. 1712. Walther, De Articulis, Ligamentis,
&c. 4to. Lips. 1728. Neumann, Lehre von d.
Articulationen d. mensch. Koerpers, Freiberg, 1745.
Isenflamm, Diss. de Ginglymo, 4to. Erlang. 1785.
Bonn, De Suturarum co:p. hum. fab. et usu, Lips.
1763. Haase, De unguine articulari ejusque vitiis,
4to, Lips. 1774; E). De fabrica cartilaginum, 4to.
Lips. 1767. Petschel, De Axungia articulari, Lips.
1740 (Recus. in Halleri Diss. Anat. select.). Weit-
brecht, Syndesmologia, 4to. Petrop. 1742 (decidedly
the best work extant on the descriptive anatomy of
the ligaments). Hunter, W. on the structure and
diseases of articulating cartilages, Philos. Trans.
1743. Schaarschmidt, Syndesmologische Tabellen,
8vo. Lange. 1782. Monro on the Burse mucose,
fol. Edinb. 1788. Heysigers, Diss. Phys. Anat.
de fabrica intima articulationum, 8vo. Traj. ad
Rhen. 1803. Loschge, Die Knochen, &c. des
mensch. Koerp. fol. Erlang. 1804. Bichat, Mem.
sur la membrane synoviale des articulations, Mem.
de la Soc. Philom. An. 6. Dickinson, A syndes-
mological chart, 8vo. Lond. 1821. Cooper, B. on
the ligaments, 4to. Lond. 1825. Crwveilhier, Sur
les cartilages diarthrodiaux, Arch. Gen. de Med.
Fevrier, 1824. Bichat, Anatomie générale. Beclard,
Anatomie générale. (The older and likewise the

VOL. I.

257

newer systems of anatomy are mostly deficient in
syndesmology; the works of Bichat and Boyer,
however, form exceptions, and are well deserving
of a careful perusal: the descriptions in the Traité
des Maladies Chirurgicales, t. iv. of the latter, are
also very excellent ; and one of the most minute
and accurate accounts we have of the ligaments is
contained in the magnificent work of Messrs.
Bourgery and Jacob, now in the course of publica-
tion: Traité complet de V’anatomie de homme;
Anglice, The whole anatomy of the human body,
by R. Willis, fol. Paris and Lond.)
(R. B. Todd.)

ASPHYXIA. (Gr. AcQvgia. Fr. Asphizie.
Ger. Scheintod, Asphyxie. Ital. Asfissia.) The
word Asphyxia, according to its derivation
(from « and c@vén, pulsus,) ought to signify
what is usually expressed by the term Syncope,
i. e. failure of the heart’s action; but it is now
always used to express failure of the process
of respiration.

It is hardly necessary to say, that there is
no more general law of vital action, in all
classes of organized beings, than its dependence
on oxygen, 1.e. On a certain chemical action
taking place between the nourishing fluids of
that living body (whether animal or vegetable)
and the oxygen of the atmosphere. This law
is, indeed, as general as the dependence of
vital action on heat, and in like manner asa
certain elevation of temperature (short of what
acts chemically on the organized textures) is
destructive to life, so a certain concentration
of oxygen in the air inhaled, at least by the
higher orders of animals, affects them as a
poison.*

Many organized substances, as the seeds,
roots, and stems of vegetables, the pup of
insects, eggs, even perfect animals of some of
the lower classes, may retain their vitality,
as is commonly said, 1. e. remain susceptible of
vital action, for very various periods of time,
at low temperatures, without exercising any
action on the oxygen of the atmosphere; but
whenever the phenomena indicating vital ac-
tion take place in them, exposure to oxygen,
and a certain alteration of the air surrounding
them, very soon become necessary conditions
of the continuance of vitality.

The alterations which take place in the air
in contact with different living bodies are some-
what various. Water is exhaled probably in
every instance. In the case of some animals,
particularly fishes, there is certainly an absorp-
tion of azote; and in that of vegetables growing
under the influence of light, there is a decided
absorption of carbon from the carbonic acid
of the atmosphere, and an evolution of pure
oxygen. But it is now generally agreed, that,
in all cases, the action between the atmosphere
and the nourishing fluid which is essential to
the motion and vivifying power of the latter,
is that which is denoted by the disappearance
of part of the oxygen from the air that comes
in contact with that fluid, and the substitution
of a quantity of carbonic acid.

Some time since it was the prevalent opinion,
that the nature of that action was merely an

* See Broughton in Journal of Science, 1830.
s

258

excretion of carbon, which immediately on its
being evolved from the nourishing fluid, en-
tered into combination with the oxygen of the
air; and was carried off; and the chief reason
for this opinion was, that the volume of oxy-
gen which disappeared in the process, was
believed to be just equal, in all cases, to that of
the carbonic acid that appeared. As it is

known that the volume of any quantity of

carbonic acid is just the same as that of the
oxygen contained in that quantity of acid, if
the fact had been as above stated, the coinci-
dence could hardly have been accidental, and
the inference would have been nearly inevitable,
that the oxygen of the atmosphere did not enter
the nourishing fluids, but merely dissolved and
carried off the excreted carbon.

But the numerous experiments of Dr. Ed-
wards* and of M. Du Long,t seem to have
nearly established the proposition, that in the
respiration of by far the greater number of
animals, the volume of oxygen that disappears
from, is somewhat greater than that of the
carbonic acid that appears in, the air employed:
the same result was obtained in experiments
by Allen and Pepys on birds ;{ and if this be
so, it is certain that the respiration of these
animals is attended with an actual absorption
of oxygen, at least to a certain extent.

This conclusion authorizes us to inquire far-
ther, whether it is not more probable, that the
whole of the oxygen which disappears from air
im contact with the nourishing fluid of living
beings, is absorbed into that fluid, and that the
carbonic acid which appears is exhaled, ready
formed, in its place. And several facts shew
that this is by far the more probable suppo-
sition; and that oxygen is essential to vital
action, not merely as a means of carrying off
superfluous carbon, which has become noxious;
but as itself an ingredient in the nourishing
Sluids, necessary for the maintenance of their
motion and vivifying power.

But without entering at length into this
question, which will be more fully discussed
under the head of Respiration, it is obvious
from what has been said, that provision must
be made, in the economy of all living beings,
for the exposure of their fluids to the air of the
atmosphere, in circumstances admitting of ex-
halation and absorption ; and it may be. farther
stated, that, in the different classes of animals,
the amount of this mutual action for which
provision has to be made, must be proportioned
to the energy and activity of vital action
which each animal is destined to exhibit, these
qualities being very generally found to be
greater, as the consumption and vitiation of the
air are more rapid.§ ;

These principles explain the intention of
-many different contrivances’ and arrangements,
afterwards to be described, which are em-

* De l’Influence des Agens Physiques sur la Vie,
p- 410, et seq.

t Journal de Physiologie, t. iv. .

t+ See Hodgkin’s Translation of Edwards, p. 486.

§ See Cuvier, La Régne Animale, t. i. p. 56;
also Marshall Hall, Philosophical ‘Transactions,
1832, p. 339.

‘ments and greater power over all functions of the

-ASPHYXIA.

ployed in different classes of animals for the =
performance of the function of respiration; and
the variations of which may be said, in a gene-
ral view, to be determined by two conditions,
first by the medium in which each animal is
destined to exist, and secondly, by the inten-
sity and variety of vital actions which it is to
be capable of performing. ong

The importance, to all living beings, of the
action of oxygen on their fluids is most un-
equivocally shewn by the nature of the fatal
changes which ensue, when that action is in
any way obstructed; i.e. by the nature of the
changes which take place in death by asphyvia.
The study of these has long been held to be
of the highest importance, not only as a car-
dinal point in physiology, but as affording the
only precise information in regard to the fatal
tendency of many and various diseases.

It is chiefly in animals of the highest orders,
i. e. in warm-blooded animals, that these phe-
nomena have been studied; and it is to be
remembered, that in them the subject is ren-
dered more complex by the higher endow-

body,which the nervous system there possesses.
When we trace the connection, in these animals,
of the different changes that precede the fatal
event, it is right to bear in mind, that the in-
terruption of the process by which their fluids
are exposed to the air is equally fatal, not only
to those animals in which no action of the ner-
vous system is concerned in that process, but
also in vegetables, where no nervous system
exists.

The phenomena of asphyxia in the higher
animals are very nearly the same, in whatever
manner the accessof air to the organs of respi-
ration is prevented. This may be done, in the
case of animals that breathe by lungs, ina
great variety of ways; by strangulation or suf-
focation, i.e. by any mechanical means pro-
hibiting the ingress of air by the trachea and
bronchi; by submersion in water or any other
fluid; by confinement in vacuo or in such
gases as contain no oxygen, but are not them-
selves poisonous, such as azote and hydrogen ;
by forcible compression of the thorax, prevent-
ing its dilatation; or by the admission of air
into free contact with the surface of the lungs
on both sides of the chest, so as to prevent
their distension, as in the celebrated experiment
of Dr. Hooke ; or by the section, either of all
the separate nerves which move the muscles
concerned in the dilatation of the thorax in
inspiration, or of the spinal cord in the upper
part of the neck, above the origin of the
phrenics, by which the whole of these nerves —
are simultaneously palsied, as in many ex- —
periments of Galen, Cruikshank, Le Gallois,
and others.* . eat:

In the case of fishes or other animals that

* These last are the lesions of the nervous
tem which cause sudden death by asphyxia. _
tion of the par vagum, the sentient nerve of
lungs, produces death by asphyxia also,
slowly, and through the intervention of disease
disorganization of the lungs, to be afterwards
ticed, r

| .

¥ - ~j —.
oe be = ba

atm, U £ 4 , st

ASPHYXIA.

breathe ‘by gills, where several of the methods
above enumerated are inapplicable, asphyxia is
produced, either by confinement in air, or in
distilled water, or water impregnated with any
gas that does not contain oxygen ; for no ani-
mal has the power of decomposing water by
its organs of respiration, to obtain oxygen,
and all aquatic animals are dependent, either
on the occasional respiration of atmospheric
air by lungs, or on the more constant respira-
tion of the air contained in water by gills or
analogous organs.

In the case of fishes breathing by gills, as
the motion of these organs is dependent on
nerves arising as high as the medulla oblongata,
injury of the nervous system must be as high
as that part, in order to produce asphyxia;
and on the other hand, in the case of birds,
where the expansion of the thorax in inspira-
tion is effected almost entirely by the motion
of the ribs, asphyxia may be produced by
section of the spinal cord in any part of the
neck.*

We exclude here entirely the cases, often
described under the name of asphyxia, in which
gases positively noxious (such as carbonic acid,
carburetted hydrogen, &c.) have been breathed,
because accurate observation shows that these
are in fact cases of poisoning, where the poison
has been introduced by the lungs, and not
simply cases of asphyxia.

The phenomena of asphyxia, in all the cases
above-mentioned, (as occurring especially in
the warm-blooded animals,) may be divided
into three stages. The first is characterized by
the intensity of the sensation which prompts to
acts of inspiration, and the consequently violent
and laborious, though ineffectual attempts to
appease that sensation by the action of all
_ the muscles of inspiration; and in some in-
Stances by other actions, voluntary or instinc-
tive, but still under the guidance of sensibility.
Lividity of the surface takes place before the
end even of this stage. The next is distinguished
by insensibility, rapidly increasing, and attend-
ed with irregular spasms or convulsions; and
the last by cessation of all effort, and of all
outward signs of life, while the heart’s action
and circulation are known still to go on fora
short time.

In the case of a warm-blooded animal (ex-
cluding the cetacea, and animals that habitually
dive) in the full possession of its vital powers,
exposed to complete and sudden obstruction of
the access of air to the lungs, it may be stated,
that the two first of these stages are very generally
Over within three minutes, seldom extending to
five, and that the circulation through the heart
has very generally ceased within less than ten
minutes from the commencement of the ob-
struction. The time during which the priva-
tion of air can be borne may be somewhat ex-
tended by habit; and there are instances of
men trained to diving in India who have re-
mained under water three, four, or even five

minutes without loss of sensibility or subse-
quent injury.

: ere in Annales d’Histoire Naturelle,

259

In cases of disease, terminating in death by
asphyxia, all these stages may often be observed
to be distinctly gone through, although in a
very gradual and somewhat irregular manner ;
the dyspnoea and lividity being succeeded by
delirium, often by spasms, and ultimately by
coma, and the respiration coming to a stand
in general a little before the action of the
heart.

The most characteristic appearance which is
seen after death by asphyxia, is simply the
great accumulation of blood in the vessels of
the lungs, in the pulmonary artery, right side
of the heart, and great veins, and the compara-
tively empty state of the left side of the heart,
the larger pulmonary veins, and the aorta. The
left ventricle is not found empty after death,
but seldom contains half as much blood as the
right; and it is in this part of the heart that the
contractions are soonest observed to cease.
The accumulation of blood in the lungs and
right side of the heart is greatest in cases where
the asphyxia has been gradual, the access of
air to the blood not having been absolutely
obstructed.*

Besides this appearance of congestion of
blood in the thorax, the liver, the spleen, and
the whole venous system in the abdomen, are
generally observed to be unusually congested
in such cases, especially those parts which are
depending after death; and even ecchymosis
on the mucous membrane of the stomach,
after strangulation, has been observed by; Dr.
Yelloly and others. This congestion of blood
in the liver, and in the veins of the abdo-
men, is remarkably observed, and leads to
important consequences, in various chronic
diseases of the thorax, threatening death by
asphyxia.

The blood after this, as after other kinds
of sudden or violent death, is usually found
fluid, and very imperfectly coagulated ; and in
connection with this state of the blood there
are frequently livid marks resembling ecchy-
mosis, (though not depending on extravasation
of blood,) in various parts of the surface of the
body, and not exclusively in depending parts,
This appearance is, of course, most remarkable
in the face and neck after strangulation, and is
much less observed on any part of the surface
after drowning.

After strangulation, if the body is soon ex-
amined, congestion of blood in the vessels of
the brain and pia mater may often be remarked,
but there is seldom any morbid effusion. After
drowning, a frothy fluid, in consequence of the
introduction of a small quantity of water, and
of efforts at respiration, is generally found in
the trachea and bronchi.

The successive steps by which physiolo-
gists have been led to what we may regard as
a satisfactory account of the phenomena now
described, and of the death by asphyxia, may
be recapitulated, as curious in themselves, and
as affording the clearest view of the evidence
on which the doctrine, which now appears to
he we.l founded, is supported.

* Bichat, Recherches Physiologiques, &c. (4th
edit.) p. 333.
$2

260

1. The first opinion on this subject, which
need be noticed here, is that which was sup-
othaty by the great Haller, viz. that the cireu-

ation, and with it all other functions of the
body are brought to a stand, because when the
movements of respiration cease, and the lungs
are no longer dilated and contracted, there is a
mechanical difficulty to the propulsion of the
blood through the pulmonary capillaries, by
which the fatal stagnation in these vessels, ob-
vious on ‘dissection, is produced.

This doctrine was satisfactorily refuted by
Goodwyn, in his treatise on the Connection of
Life with Respiration, who shewed that the
air-cells of the lungs are not necessarily con-
tracted at the time of asphyxia, and that after
having once admitted air, these cells never are
so much emptied of it again, or contracted on
themselves, as to offer any considerable impe-
diment to the free motion of blood in their
parietes. Besides, we know that the same
Stagnation in the lungs takes place in the case
of an animal confined in a gas which does not
contain free oxygen, as in the case of drowning
or strangulation, although in the former case,
any impediment to the mechanical acts of re-
Spiration that can occur, must be the conse-
quence, not the cause, of the fatal changes
within the chest.*

2. The well-known theory of Goodwyn him-
self on this subject was, that the venous blood
is not an adequate stimulus to the left side of
the heart, which in the natural state circulates
arterial blood only, and which fails to contract
upon or propel blood which has passed un-
changed through the lungs.+

This doctrine was, in its turn, refuted by
Bichat, who showed by experiment that in the
case of strangulation the venous blood does
penetrate the lungs and left side of the heart,
and is delivered from the carotid arteries if
these are punctured; that the appearance of
venous blood in these arteries is contemporane-
ous with what was described as the second
stage of asphyxia, viz. the insensibility and
spasms; and further, his experiments have
been generally admitted as affording satisfac-
tory evidence, that the circulation of venous
blood through the brain is a sufficient cause for
these symptoms, and produces them when the
venous blood from the heart of one dog is sent
to the brain of another.{ He also found by
experiment, that venous blood could be in-

jected artificially into the left cavities of the -

heart, with the effect of exciting, not suppress-
ing their action.§

3. Bichat ascribed the cessation of the circu-
lation in asphyxia, however, not to the penetra-
tion of the brain by venous blood, and the
consequent insensibility (which is now well
known to be compatible with the maintenance
of circulation for many hours, provided the

* This point has been further elucidated by some
experiments, of which an account was read, by
the author of this article, to the Medical Sections
of the British Association.

+ Connexion of Life with Respiration, p. 82.

¢ Recherches Physiolo pte &c. Art. vii.

$ Recherches, &c. p. 39 .

ASPHYXIA.

blood can be arterialized,) but to the peste
tion of the muscular substance of the heart by

venous blood, sent to it by the coronary arte-_
ries, and which he held to be equally (although

less rapidly) fatal to the vital action of this

organ, as of the brain or nerves. ;

4. Later experiments and observations have,
however, shewn that this explanation likewise
is, in some measure, incorrect. In fact, while
the free flow of venous blood in the carotid
arteries of an asphyxiated animal was urged
with perfect fairness by Bichat, as a refutation
of the theory of Goodwyn, it was with equal
justice argued by Goodwyn,* in opposition to
Bichat, that if the heart’s actions ceased in
asphyxia, only because its substance is pene-
trated by venous blood from the coronary arte-
ries, these actions could not be restored by
blowing air into the dungs and arterializing the
blood there.

Bichat, indeed, foreseeing this objection,
maintained that the artificial respiration never
is successful in restoring the circulation, unless
employed in the interval which, as was already
stated, always exists between the occurrence of
insensibility and the final cessation of the circu-
lation. But subsequent and careful observa-
tions (e.g. those of Roesler, Edinburgh Journal,
vol. xxiii) show that life has been restored, by
this means, after warm-blooded animals have
lain from twelve to seventeen minutes after
their immersion in water, i. e. until a time when
all observations made by laying open the chests
of similar animals show that their circulation
must have ceased. The records both of the
Humane Society in London and of a similar
institution in Paris, seem sufficiently to show
that resuscitation has occasionally taken place
in the human body after fifteen minutes’ im-
mersion.t And we are therefore well assured
that the arterialization of the blood at the lungs
may, in some instances, restore the natural state
of the heart’s action after the circulation has
come to a stand.

Farther, although there is a laboured attempt,
by Bichat,{ to explain the accumulation of
blood on the right side of the heart, and the
comparative emptiness of the left side, im as-
phyxia, consistently with his own explanation
of the failure of the circulation ; yet it seems
obvious, that if that explanation were correct,
the left side of the heart, receiving the venous
blood and contracting on it until it loses its
power from the penetration of its own fibres,
should be found after death distended with that
blood; and that the accumulation of blood
taking place in the lungs and right side of the
heart, indicates that the capillaries of the lungs
are the main seat of the cause which ultimately
stops the circulation. . cb a

That this is really the fact has been more —
unequivocally shown, first, by the experiments
by Dr. Williams, and afterwards by those of

SEE ee———eE— ee CCl hel _—— lll ll eS ee

* In a paper, not published till after his death,
but contained in the Edin. Med. and Surg. Journal,
July 1830. + ae

+t See Cyclopedia of Practical Medicine, art.
Asphyxia.

t Recherches, &c. art. 6.

ASPHYXIA. 261

Dr. Kay,* which we know to have been care-
fully performed, and sufficiently repeated, and
which appear to solve satisfactorily all the diffi-
culties that have been stated. Bichat had not
adverted to the length of time during which the
circulation of venous blood by the left sideof the

is carried on in asphyxia; but the experi-
ments of both Dr. Williams and Dr. Kay prove,
that this time is very short,and that before this side
of the heart has lost its contractile power, the
pulmonary veins have ceased to deliver the blood
to it, in such quantity as to maintain any effec-
tive action. A short quotation from Dr. Kay’s
paper will show the evidence for this propo-
sition.

“ Experiment 1. The trachea of a large
rabbit was tied, the abdomen and chest opened,
and at the end of the second minute from the
commencement of the experiment, the external
iliac artery was divided; a considerable
quantity of dark blood flowed, but at the
third minute it had almost ceased to escape.
The heart continued contracting vigorously ;
very small quantities of dark blood collected
slowly every twenty seconds at the extremity
of theartery. In five minutes all flow of blood
had entirely ceased. The left heart contracted
eens jor a very considerable period

nger. I repeated this experiment with simi-
far results.”+ Again, one of the variations of
the experiment was as follows: “ Experiment 3.
A rabbit was asphyxiated by tying the trachea.
The chest was opened. At the end of three
minutes and a half no pulse could be discovered
in the aorta. The left auricle was then opened,
the blood contained escaped, and for a period
of from one to three minutes, blood occasionally
collected in very minute quantities, as though
it gradually drained from the larger vessels of
the lungs, but never, as often as the experiment
was repeated, collected in quantity. The heart
continued vigorous the usual period.”

“Tn general,” says Dr. Kay, “the pheno-
mena of the cessation of motion in the left heart
in asphyxia are these. A smaller quantity of
blood is received into its cavities, and expelled
for“a time vigorously into the arteries. The
ventricle meanwhile diminishes in size, as the
quantity of blood supplied becomes less, until
at length, although spontaneous contractions
still occur in its fibres, no blood issues from a
divided artery, and the ventricle, by contrac-
tion, has obliterated its cavity. After this,
blood slowly accumulates in the auricle from
the large vessels of the lungs; and its con-
tractility continues for a very considerable
period.’’f

Farther experiments by Dr. Kay show, that
after the aorta of an animal has been tied, and
after the muscles of its lower extremities have,
in consequence, gradually lost all contractile
power, that power is restored for a time by the
ei of venous blood into the lower portion
of the aorta ;§ and from these, and from some

* Edinburgh Medical and Surgical Journal, vol.
xix. and xxix. :

+ Edinburgh Journal, vol. xxix. p. 42.
t Ibid, p. 46.
§ Ibid, p. 53 and 54,

experiments by Dr. Edwards,* we learn, that
the venous blood, though less powerful than
arterial in maintaining the vital power of mus-
cles, is by no means rapidly destructive to it.

The changes in asphyxia, in the warm-blooded
animals, have, therefore, of late been generally
thought to be as follows :—that the venous blood,
though more or less noxious to all parts of the
body which it fully penetrates, is nevertheless
transmitted through thelungs in the first instance,
in sufficient quantity to stimulate the left side of
the heart, and is sent from thence in sufficient
quantity to penetrate the brain;—that by its
action there it destroys the sensibility, but that
it passes more and more slowly through the
pulmonary vessels, and after a few minutes is
no longer delivered to the left side of the heart
in such quantity as to keep up regular and
efficient contractions there; and that thus,
while the animal life is suddenly extinguished
by the noxious influence of venous blood on
the brain, the organic life is more gradually
brought to a stand by its noxious influence in
the lungs, and the consequent failure in the
supply of blood to the left side of the heart.

is explanation is consistent with all the
phenomena, and particularly with the very
rapid restoration of the flow of blood by the
admission of air to the lungs of half-asphyxiated
animals, stated by Bichat himself as a difficulty
in his view of the subject.

The more recent experiments by Dr. Kay
had, however, led him to question the validity,
even of that part of Bichat’s doctrine, which
has been most generally admitted, viz. the ra-
pidly noxious effect of venous blood on the
brain and nerves. He found, in various cases,
that large quantities of blood from the veins of
one rabbit could be injected (slowly and cau-
tiously, so as to avoid all injury of the cerebral
matter) into the carotid arteries of another, with-
out causing more than muscular debility and
lassitude; so that he considers venous blood to
be only a weaker stimulus to the brain than
arterial, not a direct poison to it; and thinks
the sudden insensibility of asphyxia is to be
explained by the rapid diminution of the quan-
tity, not by the change of quality, of the blood
sent to the brain from the heart.t

And when we bear in mind the fact stated
in the outset of this inquiry, that the motion
and vivifying power of the nutritious fluid is
dependent on its exposure to oxygen, not only
in the higher anima!s, but even in the lowest
tribes, and in vegetables, where neither heart
nor nervous system exists ; it appears reasonable
to suppose, that the chief impediment to the
blood’s motion, from the failure of the supply of
oxygen, will be in the lungs themselves, where the
venous blood isaccumulated in the greatest quan-
tity, and where all the minute vessels carrying it
must be most completely exposed to its acticn,

But before we can be completely satisfied
upon this subject, it will be necessary to carry
the inquiry one step further, and to ascertain
in what manner the change from venous to

* De l’Influence, &c. p. i. ch. i. and p. iv. ch. 4
+ Treatise on Asphyxia, p. 193 et seq.

262 ASPHYXIA.
tion, although applied at the extremity of the —

arterial blood so greatly promotes the flow of
blood through the capillaries of the lungs, and
how the presence of venous blood in the begin-
nings of the pulmonary veins can so effectually
retard it, that the action of the right ventricle of
the heart, though continuing vigorous for a
time thereafter, fails of its wonted effect, and the
blood stagnates in those capillaries.

The common expression employed on this
subject is, that arterial blood is a stimulus
peculiarly adapted to excite the capillaries of
the lungs and pulmonary veins; and _ that
venous blood stagnates in those capillaries for
want of power to excite them. But it must
be remembered that we have no distinct evi-
dence of the existence of ccats, still less of
irritable coats in the minute capillaries of the
lungs ;* that although the circulation there has
been often examined with the microscope, no
contraction of the vessels has ever been ob-
served ; that the only vital power of contrac-
tion which experiments authorize us to ascribe to
any arteries, is a power of permanent or tonic
contraction on their contents, which, when
called into action, lasts for some time, and
while it lasts must obviously impede the flow
of fluids through these vessels ; that on these
grounds Magendie and other eminent physio-
logists believe the only power, which arteries
can exercise over their contents, to be simply a
power of either relaxing, so as to give them a free
passage, or contracting so as to lessen and re-
tard their flow;+ and that, conformably with
these views, it was found by Wedemeyer, that
when he injected stimulating liquids into the
arteries of living animals, they were much
longer of making their way into the veins, than
mild liquids were.{

These considerations evidently point to the
conclusion, that, if the difference depend on any
vital action of vessels, venous blood,which makes
its way so slowly through the capillaries of the
lungs, must be the stronger stimulus to them, and
that arterial blood, which is transmitted so readily,
must act as a sedative, to the only vital action
of which these vessels are susceptible. But
this conclusion is again strongly opposed by
the fact, that in all other instances, in relation
to muscular contraction, to the functions of
the nervous system, and of secreting organs,
arterial blood, and the oxygenated fluids in
general, manifestly possess the stimulating
power, and venous blood or carbonized fluids
the sedative.

In this difficulty it is important to remember,
that we have many facts to indicate the exist-
ence of powers which move the blood and
other organized fluids in living animals, inde-
pendently of any contractions of moving solids.
It would appear that the power by which any
texture is nourished, or secretion or excretion is
formed from the blood, in any part of the circu-
lation, is, to a certain degree, a cause of move-
ment of the blood towards that part,and that any
stimulus given to such act of nutrition or secre-

* See Marshall Hall on the Circulation, p. 47.

+ Physiology, translated by Milligan, p. 409-10.
Mayo’s Outlines, (2nd edit.) p. 87 et seq.

} Edinburgh Medical Journal, July 1829, p. 90,

ae

capillaries, produces an effect on the circulation
which, as Sir C. Bell expresses it, is retrograde
along the branches of the arteries. Thus, the flow
of blood to the mucous membrane of the stomach
and bowels during digestion, to the uterus during
gestation, to the mamme during lactation, to
any part of the body during inflammation, sup-
puration, or the growth of a tumour, is excited
by causes acting at the extremities of the arte-
ries of these parts; although there is the same
difficulty in all these cases, as in the case of the
lungs, in understanding how a cause acting
there, and exciting the only vital power which
arteries can be shewn to possess, should in-
crease the flow of blood through them.

It is always to be remembered, that pre-
cisely analogous phenomena are observed from
the application of heat, or other stimuli, to
single branches, or roots, of vegetables, where
there is no evidence of the existence, either
of a structure or of a contractile power, m
the vessels or cells through which the fluids
pass, capable of giving them a determinate
direction towards the parts, which are thus
stimulated ; and where the movement of fluids
that can be seen, (in the case of those plants
that have milky juices,) is not only unattended
with any visible contraction of solids, but is
of a kind, (as the recent observations of
Schultze, Amici, Raspail, and others indicate,)
which no contractions of solids appear capa-
ble of producing.

It is farther to be observed, that when venous
blood becomes arterial, it acquires an increase
of fibrin,* and that its tendency to coagulation
is decidedly increased ,+ which implies such an
increase of an attraction of aggregation in the
particles of the fibrin, as may be held to
be strictly vital. And on the other hand,
when arterial blood becomes venous, according
to the microscopical observations of Kalten-
brunner, its globules seem to separate some-
what from one another, and its whole bulk ap-
pears somewhat increased.f

Lastly, it is to be remembered, that when a
vessel is opened in a living animal, and the
blood exposed to the air, the consequence is,
a movement of derivation of the blood, in all
directions, towards the aperture ; which is cer-
tainly altogether independent of the heart’s
action, and which the elaborate investigations

of Haller led him (and apparently with good

reason) to think inexplicable likewise by any
contraction of vessels.$

The consideration of all these facts may
lead us strongly to suspect, that the stimulus
to the circulation which is given by the arte-
rialization of the blood, and which we have
found to act chiefly in the capillaries of the
lungs, is of the nature of an attraction of the

venous blood towards the part where it isto

* Prevost and Dumas, An. de Chimie, t. xxiii,
+ See particularly Schroeder Van der Kolk, Com. —

de Sanguine Coagulante.
& 357.

seq.

¢ Experimenta circa Statum Sanguinis, &c. § 281 4

§ Mem. sur le Mouvement du Sang, p. 336 eta

:

ee ee ee

ASPHYXIA. 263

undergo this change, and towards the arterial
blood in advance of it in the vessels; not of
the nature of an increased contraction of the
vessels themsleves; and that it is in conse-
quence of the failure of this auxiliary power
in the circulation, that the stagnation of the
blood in the lungs in asphyxia, and the extinc-
tion of the organic life, are effected.

What has been said of the manner in which
death is produced in asphyxia, enables us to
understand in what circumstances it can ha
pen, that life may be retained, even by a
warm-blooded animal, for an unusual length
of time, without respiration. As the stop to
the circulation is the immediate cause of death,
it is obvious that an animal which can exist for
a time, in a lowered state of vitality, with
little or no circulation, will during that time
require no exposure of its blood to air, to
maintain that grade of vitality; and farther
that in such an animal, as the brain will not
suffer from the afflux of venous blood, and as
the lungs will not be hurtfully congested, these
organs will retain a condition much better
adapted for the recovery of their functions,
than they will in those cases where asphyxia
is produced at atime when the circulation is
vigorous.

Hence we can easily understand, that per-
sons who are ina state of syncope, (from a
temporary cause,) in whom the circulation is
nearly at a stand before the access of air to
their lungs is obstructed, may survive a longer
suspension of the acts of respiration than per-
sons in health. This has been stated, by Des
Granges and Foderé, as the explanation of
some cases in which it appears certain, that
recovery has taken place after fifteen minutes
or more of submersion in water.*

The case of hybernating animals was, until
lately, considered to be of this nature, i.e. it
was supposed that circulation is gradually sus-
pended in those animals, simultaneously with
respiration, and therefore that such animals,
although consuming little or no air, did not
suffer the noxious influence of venous blood
on their solids, and remained susceptible even
of sensation. But the experiments of Dr.
Marshall Hall+ appear to have established that
in warm-blooded hybernating animals in the
complete state of torpor, when respiration is
quite at a stand for many hours, circulation,

although slow and feeble, still goes on regu-
larly; so that we must suppose the essential

peculiarity of these animals, during the state

of lowered vitality, to which they are reduced
by cold, to be this, that the venous blood has

little of the noxious effect, in any part of the

system, which it has, on them as on other

animals, during the state of activity; it has
neither the same difficulty of making its way

through the lungs, nor the same destructive
influence on the brain.}

* Foderé, Med. Legale, § 613.

+ Phil. Transactions, 1832,

¢ Dr. M. Hall considers the essential peculiarity
of these animals to be, that the left side of the
heart in them, is irritable by venous blood; but as
it appears from the facts above stated, that the

The nearest approach to this mode of vita-
lity in the human body, is in the case of the
new-born child, which has never felt the in-
fluence of perfectly arterial blood, and which
has been known to live, although its natural
respiration was not established for nearly an
hour after birth.

The study of the fatal changes in asphyxia
is also of peculiar importance as illustrating
the manner in which the circulation, and the
organic functions maintained by it, are con-
nected with the nervous system. It will be
observed, that as the vitality of hybernating
animals, during the state of torpor, is inde- |
pendent of respiration, so it is also, in a great
measure at least, independent of the larger
masses of the nervous system; and Dr. M.
Hall found, by experiment in a hedgehog in
this state, that the circulation went on regu-
larly for ten hours afier the gradual but com-
plete destruction of the brain and spinal cord.

Indeed, the maintenance of the circulation
after the head of an animal has been cut off,
by the artificial respiration, i. e. by inflating
its. lungs in a manner resembling its natural
breathing, (which has been so often practised
by Fontana, Cruikshanks, Bichat, Brodie, Le
Gallois, Wilson Philip, and others,) is in it-
self a clear proof that the circulation, and
other functions of organic life* in animals,
are necessarily and immediately dependent on
the animal life, only inasmuch as the natural
respiration of animals, and the arterialization of
their blood, are dependent on sensation. And ac-
cordingly we know, that in that stage of animal
existence, where the supply of sufficiently
arterialized blood is provided for without the
intervention of sensation, i.e, in the fetus in
utero, the whole organic life is altogether in-
dependent of the animal, and goes on perfectly,
not only before sensation is felt, but even in
cases where the essential organs of sensation
and of voluntary motion, the brain and spinal
cord, do not exist. It is not until the moment
of birth, when the arterialization of the blood
is put in dependence on sensation,—that the
brain and spinal cord become essential for the
maintenance of organic life; or that we possess
any proof of influence being exercised by the
nervous system, over that part of the animal
ceconomy.

It seems probable, that if we possessed the
means of making the artificial respiration ex-
actly similar to the natural, and neither injuring
the structure of the lungs, nor introducing
more air into them than is useful, in practising
it, the circulation, and perhaps all the func-
tions of organic life, might be maintained, after
the head of an animal is cut off, until nearly
the time when it must fail for want of nourish-
ment; but it must also be remembered, that
in the adult animal, as the experiments of Le

stop to the circulation in asphyxia is at the lungs,
the chief peculiarity of these animals must lie
there also.

* By organic life, we mean those vital acts which
take place without the intervention or consciousness
of the mind ; by animal life, those in which some
mental act is an essential constituent.

264

Gallois, Dr. Wilson Philip, Flourens, and
others have shewn, injuries of the brain and
spinal cord, (particularly injuries suddenly in-
flicted on any large portions of these organs,)
may directly influence, or even wholly sup-
press, vital actions belonging to the head of
organic life, for the performance of which we
have no evidence of their furnishing any ne-
cessary condition.

As the function of respiration thus appears
to be the only link by which the organic life
is immediately and necessarily connected with
animal life, it is naturally to be expected that
the extinction of animal life should affect the
organic functions just in the same way as the
suspension of respiration does, and therefore
that in the case of death beginning at the
brain, as Bichat expressed it, (2. e. of death
consequent on the extinction of sensation and
voluntary motion,) the circulation and other
organic functions should be brought to a stand
just in the same manner as in death by as-
phyxia. And in what is strictly called death by
coma, thisis really the case ; the sensations being
gradually more and more impaired, the sense
of anxiety in the chest, which prompts to the
acts of respiration, is ultimately extinguished ;
but even after the last breath has been drawn,
the pulsations of the heart still continue, and
the blood then gradually stagnates in the lungs,
the circulation comes to a stand, and the blood
is found after death congested on the right side
of the heart, just as in the case of asphyxia
already described.

That this is truly the mode of fatal termina-
tion in cases where death takes place strictly
in the way of coma, was first unequivocally
proved by Sir B. Brodie,* who found, by experi-
ment, that animals poisoned by opium or
other narcotics, and in which the acts of re-
spiration had ceased, in consequence of the
impression made on the brain and the gradu-
ally increasing insensibility, might be recovered
by the artificial respiration, just as asphyxiated
animals may be. Indeed the same expedient
had been previously employed with success
(although not suggested by an equally accurate
view of its mode of action) by Mr. Whately.+

The reason why the same expedient cannot
be expected to avail in cases of disease termi-
nating by coma is simply that in these cases
the cause of the coma is not temporary, like
the effect of a narcotic poison, but permanent.
It seems possible that it may yet be found
successful in some cases of insensibility with
convulsion, in children, unconnected with or-
ganic lesion.

In so far, therefore, as the extinction of the
organic life is concerned, the death by coma,
or beginning at the brain, resolves itself into the
death by asphyxia, or beginning at the lungs,
the difference lying merely in the mode in
which the arterialization of the blood is ar-
rested.

But although this is strictly true as to cases

* Phil. Transactions, 1812.
i London Medical Observations and Inquiries,
vo . vi.

ASPHYXIA. Oi eae ae

of violent death, produced experimentally in
such a way that a single cause only is allowed =
to operate ; and although we occasionally meet
with cases of equal simplicity in disease, and
ought always to keep i view the principles
which these simple cases illustrate in the treat-
ment of disease, yet it ought not to be sup-
posed that either the death by asphyxia, that
by coma, or that by syncope, often present
themselves to the observation of the medical
practitioner in the same simplicity as to the
experimental physiologist. We can state from
frequent observation, that it is only in a certain
number of cases of disease, strictly belonging
to the head, such as apoplexy or hydrocephalus,
that death takes place exactly in the way of
coma, as above described, or that the function
of circulation can be observed to survive that
of respiration; and on the other hand there
are many instances of disease of the lungs,
particularly of phthisis, in which the ultimate
extinction of life is rather in the way of syncope
than of asphyxia. The simple principle, that
the circulation, though not dependent on any
action of the nervous system, is liable to be
influenced in various ways by causes acting
on the nervous system, enables us to under-
stand that death may often take place, in the
course of diseases, in a way different from that
which the seat of the disease may lead us to
anticipate.

Nevertheless it may often be of real and
practical importance, with the view of ac-
quiring clear and precise ideas of the modes
of fatal termination which are to be expected
in the course of diseases, and particularly of
such diseases as fever—where the symptoms
immediately preceding death, and the causes
evidently inducing death, are remarkably various
in different individual cases,—to study atten-
tively the phenomena, and causes, of the
fatal termination, in the simpler cases of violent
death, such as those which have been here
considered.

BIBLIOGRAPHY.— Testa, Della morte apparente,
8vo. Firenz. 1780. Coste, Mem. sur les asphyxies,
8vo. Philad. 1780. Previnaire, Traité sur les as-
phyxies, 8vo. Paris, 1788. Kite, Essay on the
recovery of the apparently dead, 8vo. Lond. 1788.
Goodwyn, The connexion of life with respiration,
8vo. Lond. 1789. Portal, Obs. sur les effets des
vapeurs mephitiques dans homme, &c. 8vo. Paris,
1791. Coleman, A dissertation on suspended respi-
ration, 8vo. Lond. 1791. Curry on apparent
death, 8vo. Lond. 1792. Fothergill, Preservative
plan; or, hints, &c. 8vo. Lond. 1998, Graf, Dis.
sur l’asphyxie, Strasb. 1803. Bichat, Sur la vie et
la mort, Paris, 1805. Guillebout, Indic. des affec-
tions qui produisent subitement la mort, &c. 4to.
Paris, 1812. Colorini, Sulle varie morti apparenti,
8vo. Pavia, 1813. Lebel, Consid. sur la maniére
dont la mort arrive dans quelques maladies des
organes de la respiration, 4to. Paris, 1815. Orfila, —
Secours a donner aux personnes empoisonnées ou
asphyxiées, 12mo. Paris, 1818. White, A disser- ~~
tation on death and suspended animation, 8vo. —
Lond. 1819. Gummer, De causa mortis submer- —
sorum, Groning. 1761. Recus. in Sandif. Thes,
vol. i. Champeaux et Faisole, Exper. sur la cause
de la mort des noyés, 8vo. Lyon. 1768. DuChemin
d@’Etang, Mem. sur la cause de la mort des noyés : ?
reponse a MM. Champeaux et Faisole, 8vo. Paris,

wi

AVES.

1770. Fothergill, New inquiry into the suspension
of vital action, &c. 8vo. Lond. 1795. Caillau,
Mem, sur |’asphyxie par submersion, 8vo. Bordeaux,
1799. Fine, De la submersion, 4to. Paris, 1805.
Berger, Essai sur la cause de l’asphyxie par sub-
mersion, 4to. Paris, 1805. Ploucquet, Animadvers.
in statum ac therap. submersorum, 4to. Tubing.
1799. Hunter, Animal economy, 4to. Leroy,
Recherches sur les asphyxies, 8vo. Paris, 1829.
Devergie, Dict. de Med. et Chir. Prat., art. As-
phyxie. Roget, in Cyclopedia of Practical Medi-
cine, art. Asphyzia. Kay, on asphyxia, 8vo. Lond.
1834 ( the most complete and able work on this subj. ct
in the English language ). Edwards, Sur influence
des agens physiques, Englished by Drs. Hodgkin
and Lister, Appendix, p. 463.

(W. P. Alison.)

AVES, birds; (Gr. Ogubes; Fr. Oiseauz ;
Germ. V ogeln; Ital. Uccelli:) a class of ovi-
parous vertebrate animals, with warm blood,
a double circulation, and a covering of feathers.

Birds are organized for flight, and as this,
the most vigorous kind of locomotion, demands
the greatest energy in the contractility of the
muscular fibre, so the respiratory function finds
its highest development in the present class.
Not only the ramifications of the pulmonary
artery, but many of the capillaries of the sys-
temic circulation, from the singular extension
of the air-cells through the body, are sub-
mitted to the influence of the atmosphere, and
hence birds may be said to enjoy a double re-
spiration.

Although the heart resembles in some parti-
culars that of the Reptilia, the four cavities are
as distinct as in the Mammalia, but they are
relatively stronger, their valvular mechanism is
more perfect, and the contractions of this organ
are more forcible and frequent in Birds in ac-
cordance with their more extended respiration
and their more energetic muscular actions.

As Birds exceed Mammals in the activity
of those functions on which the waste and
renovation of the general system more imme-
diately depend, so they possess a higher stan-
dard of animal heat: their ordinary tempera-
ture is 103° and 104°, and according to Cam-
per is occasionally as high as 107° Fahr.

The modification of the tegumentary cover-
ing characteristic of the present class is to be
regarded rather as dependent upon, than oc-
casioning, this high degree of internal tem-
perature, which requires for its due mainte-
nance against the agency of external cold an
adequate protection of the surface of the body
by means of non-conducting down and imbri-
cated feathers ; and this warm clothing is more
especially required to meet the sudden vari-
ations of temperature to which the bird is
exposed during its rapid and extensive flights.

e generative sacs is always excluded
from the oviduct in an undeveloped state, in-
closed, in a liquid form, within a calcareous
case or shell. The female organs are, therefore,
developed only on the left side of the body.
The ovum is subsequently perfected by means
of incubation, for which action the bird is es-
polly adapted by its high degree of animal

t.

Birds form the best characterized, most dis-

265 |

tinct, and natural class in the whole animal
kingdom, perhaps even in organic nature
They present a constancy in their mode of
generation and in their tegumentary covering,
which is not met with in any other of the
vertebrate classes. No species of Bird ever
deviates, like the Cetacea among Mammals,
the Serpents among Reptiles, and the Eels
among Fishes, from the tetrapodous type of
formation which so peculiarly characterizes the
vertebrate division of animals.

The anterior extremities are invariably con-
structed according to that plan which best adapts
them for the actions of flight ; and although, in
some few instances, the development of the
wings proceeds not so far as to enable them to
act upon the surrounding atmosphere with suffi-
cient power to overcome the counteracting
force of gravity ; yet, in these cases they assist,
by analogous motions, the posterior extremities ;
either, as in the Ostrich, by. beating the air
while the body is carried swiftly forward by the
action of the powerful legs; or, as in the Pen-
guin, by striking the water after the manner of
fins, and by the resistance of the denser me-
dium carrying the body through the water in a
manner analogous to that by which the birds
of flight are borne through the air. Ina few
exceptions only are the wings reduced to mere
weapons of offence, as in the Cassowary and in
the singular Apteryx of New Zealand, in which
they are represented by a single spur. In no
instance do the anterior extremities take any
share in stationary support or in prehension.

Birds are therefore biped, and the ope-
rations of taking the food, cleansing the
plumage, &c. are almost exclusively performed
by means of the mouth, which consists of two
unlabiate and edentate mandibles, sheathed
with horn. To facilitate the prehensile and
other actions thus transferred to the head, the
neck is elongated, and the body generally in-
clined forwards and downwards from the hip-
joints. The thighs are accordingly extended
forwards at an acute angle from the pelvis to-
wards the centre of the trunk, and the toes are
lengthened and spread out to form an adequate
base of support. The actions of perching,
walking, running, scratching, burrowing, wa-
ding, and swimming, require for their perfect
performance different modifications of the pos-
terior extremities. The mandibles, again, present
as many varieties of form, each corresponding to
the nature of the food, and in some degree in-
dicative of the organization necessary for its
due assimilation. Ornithologists have, there-
fore, founded their divisions of the class chiefly
on the modifications of the bill and feet. Since,
however, Birds in general are associated to-
gether by characters so peculiar, definite, and
unvarying, it becomes in consequence more
difficult to separate them into subordinate
groups, and these are necessarily more arbi-
trary and artificial than are those of the other
vertebrate classes.

A binary division of the class may be found-
ed on the condition of the newly-hatched
young, which in some orders are able to run
about and provide food for themselves the mo- ~

266

ment they quit the shell (Aves precoces) ;
while in others the young are excluded feeble,
naked, and blind, and dependent on their pa-
rents for support (Aves altrices ).

_ Scoproui, in his ‘ Introduction to Natural
History,’ published in 1777, proposed a dicho-
tomous systematic distribution of Birds, found-
ed on the form of the scales covering the
tarsus. The species which have these scales
small and polygonal are the Retepedes of this
author; those which have the legs covered
anteriorly with unequal semicircular plates are
the Scutipedes.

Nritzscu,* the celebrated professor of natural
history at Halle, has synthetically grouped to-
gether the feathered tribes under ¢hree grand
orders, according to the great divisions of the
terraqueous globe which form the principal
theatres of their actions.t The first order con-
sists of the birds of the air par excellence, Aves
aeree (Luft-végeln); the second order em-
braces the birds of the earth, Aves terrestres
(Erd-vogeln) ; the third great division includes
the birds which frequent the waters, Aves aqua-
tice (Wasser-vogeln). The Eagle and the
Sparrow may be named as examples of the first ;
the Ostrich and the common fowl of the
second; the Heron and the Gull of the third
of these extensive divisions.

A more definite arrangement of Birds, in
which a similar principle may be traced, has
been proposed by a distinguished naturalist of
ourown country, Mr. Vicors. He divides the
class Aves into five orders. The first includes
the birds which soar in the upper regions of the
air, which build their nests and rear their
young on the highest rocks and loftiest trees,
and which may be regarded as the typical
species of Nitzsch’s Aerial Birds ; this order is
termed Raptores, from the rapacious habits
and animal food of the species so grouped to-
gether.

The second order affects the lower regions of
the air; the birds composing it are peculiarly
arboreal in their habits, and are therefore térm-
ed Perchers or Insessores.

The third order corresponds to Nitzsch’s
Aves terrestres, and is denominated Rasores,
from the general habit which these granivorous
species present of scratching up the soil to
obtain their food.

By dividing the aquatic birds of Nitzsch into
those which frequent the fresh waters, and are
limited to wading into rivers, lakes, &c. in
search of their food, and those which possess the
power of swimming in the great ocean, we ob-
tain the two remaining orders of the quinary
arrangement of Mr. Vigors, viz. the Grallatores,
or Waders, and the Natatores, or Swimmers.
The merit of this system is not, however,
confined to the defining of the different groups
in as clear and readily appreciable a manner as
the subject will admit; but it also aims at

* See Schoepfs, in Meckel’s Archiv fiir Physio-
logie, B. 12, p. 73. =

+ Blumenbach more vaguely proposes a Binary
arrangement of Birds on the same principe ; he
divides the class into Land- Birds and Water- Birds,
In Lawrence’s Blumenbach, Comp, Anat, p. xxxili.

AVES.

displaying the natural affinities by which the =) a
several orders and families are connected with
and pass into one another. In the ornitholo- =
gical systems of other naturalists, who have
made this branch of zoology their particular
study, we find the greatest discrepancy both as
to the number and value of the primary divi-
sions of the class.

Sandewall has four orders or cohorts.

Vieillot, like Vigors, has five orders.

Linneus, Cuvier, Carus, and Dumeril have

six orders.

Illiger has seven. ‘it

Scopoli, Latham, Meyer, Wolf and Blain-

ville have nine.

Temminck (1820) has sixteen.

Scheeffer has seventeen.

Brisson has twenty-eight, and

Lacepede has thirty-eight orders.

Where so many masters of the science differ,
it is difficult for one less profoundly versed in
ornithology to select the most unexceptionable
system of arrangement, and as Kirsy* ob-
serves, ‘ the choice perplexes.’ We have here
adopted the arrangement proposed by ‘that dis-
tinguished naturalist as being the one which
facilitates the expression of the leading ana-
tomical differences which obtain in the class of
Birds, and which may therefore be considered
as the most natural.

OrpERS.
I. Raprores, Vig. Syn. Accipitres, Linn.
Cuv. Birds of Prey or Raveners.t
II. Insessores, Vig. Passeres, Linn. Cuv.
Perchers.

III. Scansores, [llig. Cuv. Climbers.
IV. Rasorss, Llig. Galline, Cuv. Scratchers.
V. Cursores, Illig. Brevipennes, Cuv.
Coursers.
VI. Gratratores, Illig. Gralle, Linn. Cuv.
Waders. = Ck ee
VII. Naratores, Illig. Palmipedes, Cuv.;

Anseres, Linn. Swimmers.
The following are the characters of these orders.
Class Aves ( Birds. )
Animal vertebrated, oviparous, biped.
Anterior extremities organized for flight.
Integument plumose.
Blood, red, warm.
Respiration and circulation double.
Lungs fixed, perforated.
Negative characters, no auricles, lips, teeth,
epiglottis, diaphragm, fornix, corpus callosum,
scrotum.

Order I. RAPTORES.

Body, very muscular.

Beak, strong, cur-
ved, sharp-edged and
sharp-pointed, often
armed with a lateral
tooth; upper man-
dible the longest.

(Fig 112.)

Fig. 112.

* Bridgewater Treatise, vol. ii. p. 444. a
+ This word is proposed by Mr. Kirby as the ©
English for Raptores ; it is the substantive of rave-
nous, from the verb to raven, - oa

_ have a prompt,

‘struction of their nests.

AVES. 467

~ Legs, ‘robust,
short, with three
toes before, and
one behind; all
armed with long,
Strong, crooked
talons. Fig.113.

All the Birds
of Prey feed on
the flesh of living
or recently killed
animals. They

powerful, and rapid flight. They are mono-
gamous; the female exceeds the male in size.
They nidificate in lofty situations and rarely
lay more than four eggs: the young are ex-
cluded in a blind and feeble state.

The Birds of Prey are either diurnal or noc-
turnal.

The Diurnal Raptores have their eyes di-
tected laterally, and are divided into the fol-
lowing families— Valconide, Eaglesand Hawks ;
Vulturide, Vultures ; and Gypogeranide, which
includes the Secretary vulture. In the first two
divisions the characters of the order are most
strongly marked ; in the third the legs deviate
from the ordinal character and are remarkably
elongated, adapting it to an inferior kind of
prey, viz. noxious reptiles, serpents, &c.

The Nocturnal Raptoreshave the eyes directed
forwards, and include the Strigide or owl-tribe.

Order II. INSESSORES.

Legs slender, short, with three toes before
and one behind, the two external toes united
by a very short membrane.*

The Perchers form by far the most nume-
rous order of birds, but are the least easily
recognizable by distinctive characters common
to the whole group. Their feet, being more
especially adapted to the delicate labours of
nidification, have neither the webbed struc-
ture of those of the Swimmers, nor the
robust strength and destructive talons which
characterise the feet of the Bird of Rapine,
nor yet the extended toes which enable the
Wader to walk safely over marshy soils. and
tread lightly on the float-
ing leaves of aquatic
plants; but the toes are
slender, flexible, and
moderately elongated
with long, pointed and
slightly curved claws.
( Fig.114.)

The perchers in general have the females
smaller and less brilliant in their plumage than
the males; they always live in pairs, build in
trees, and display the greatest art in the con-
The young are ex-
eluded in a blind and naked state, and wholly
dependent for subsistence during a certain

* The genus Ceyr, Lacép. (Alcedo tridactyla,
Pall.) affords an exception, the inner toe being
deficient; and the two other anterior ones being
united as in the other Syndactyles, it appears’ as
if there was but one toe in front opposed to one

behind.

period on parental care. The brain arrives in
this order at its greatest proportional size; the
organ of voice here attains its utmost com-
plexity, and all the characteristics of the bird,
as power of flight, melody of voice, and
beauty of plumage are enjoyed in the highest
perfection by one or other of the groups of this
extensive and varied order.

The beak of the Insessores varies in form
according to the nature of their food, which
may be small or young birds, carrion, insects,
fruit, seeds, vegetable juices, or of a mixed
kind. The modifications of the rostrum
have therefore afforded convenient characters
for the tribes or subdivisions of the order ;
these are termed, 1, Dentirostres ; 2, Coniros-
tres; 3, Tenuirostres; 4, Fissirostres.

The Dentirostres, (fig. 115)
characterized by their insect
food, and the notch near the
extremity of the upper man-
dible, include the families
termed Laniade or Shrikes ;
Merulide, Thrushes; Sylvi- Rostrum ofa Shrike
ade, Warblers; Pipride, Tits; and Muscica-
pide, Fly-catchers. —-

The Conirostres (fig. 116) include the two

ss inn
Rostrum of a Crow.
orders of M.Temminck, termed Omnivores and
Granivores ; and are characterized by a strong
and conical beak, the margin of which is gene-
rally entire; the greater part are omnivorous,
the rest granivorous; these latter are the Hard-
billed Birds of Ray. The families of the tribe
are the following: Sturnide, Starlings; Cor-
vide, Crows; Buceride, Hornbills; Loxriade,
Cross-bills ; Fringillide, Finches, Larks.
The Tenuirostres
(fig. 117) or suctorial
birds form, Mr.Vigors
observes, “ the most
interesting group, per-
haps, of the animal Rostrumof theOrthorhynchus,
world. Deriving their or Straeght-billed Humming
subsistence for the most Bird.
part from the nectar of flowers,* we never fail to
associate them in idea with that more beautiful
and perfect part of the vegetable creation, with
which in their delicacy and fragility of form,
their variety and brilliancy of hues, not less than
by their extracting their nourishment from
vegetable juices, they appear to have so many
relations. As the tribe is confined exclusively
to the torrid zone and southern hemisphere,
the naturalists of our northern latitudes have
little opportunity of observing their manners
or of inspecting their internal construction.” +

Fig. 117.

* In the Humming-Birds which we have dis-
sected, we have found the remains of minute insects
in the gizzard, :

+ We have selected the skeleton of the Humming-
bird, one of this tribe, as a striking illustration of the

268

This distinguished ornithologist proposes to
divide the Tenuirostres into the following
families: Cinnyrid@, Sugar-eaters ; Trochilide,
Humming-birds ;—in which families the beak
and feet are more remarkable for their tenuity
and length: and Promeropide, Hoopoes; Me-
liphagide, Honey-suckers ; Nectariniade, Nec-
tar-birds ;—in which the slenderness of the beak
and feet is less remarkable.

Fie. 118. The Fissirostres, (fig.
geiens 118 ), like the Tenuirostres,
it oN are distinguished by a habit

of feeding on the wing, but
as their food, instead of
Rostrum of the vegetable juices, consists of
Caprimulgus. living insects, the form of
the beak is modified accordingly, and is re-
markable for its shortness and the wideness
of its gape, especially in the typical families.
In these the mode of catching the prey 1s con-
formable to their distinguishing characters ; they
receive it in full flight into the cavity of their
mouths, which remain open for that purpose, and
where a viscous exudation within and a strong
fence of vibrisse on the exterior, assist in secur-
ing the victim. The longer-billed Fissirostres,
on the other hand, seize their food by their bills.
The following are the families of the Fissirostral
tribe: Hirundinide, Swallows; Caprimulgide,
Goat-suckers; these are characterized by the

short, wide, and weak bill. Todide, Todies ;
Halcyonide, King-fishers ; Meropida, Bee-
eaters; these latter fa- Fig. 119.

miliesare characterized
by their stronger and
longer bill, and fur-
ther differ from the
preceding in having
the external toe nearly
as long as the middle
one to which it is
united as far as the
penultimate joint; they
are therefore termed
Syndactyles by Cuvier.
Fig.119 represents the
foot of the King-fisher.

Order III. SCANSORES.

Feet with two
toes before and one
behind. (¢ Fig. 120.)
The disposition of
the toes which re-
sults from the ex-
ternal one being
turned back like the
thumb, gives the
Scansores great fa-
cility in climbing
the branches. of
trees, but proporti-
onally impedes their
progression along
levelground.* Their

Foot of the Woodpecker.

adaptation of the vertebrate skeleton to powers of
flight.

* There are peculiar exceptions to the general
character in this as in most other orders of birds.

AVES.

nests are less skilfully constructed than those
of the Insessores, and are generally made in
the hollows of old trees ; one family, indeed,
is remarkable for depositing its eggs in the
nests of other birds. Their powers of flight
are moderate ;* their food consists of insects -
and fruit. The scansorial families are the
Psittacide, Parrots; Picide, Woodpeckers,
Wry-necks; Cuculide, Cuckoos; Rhamphas-
tide, Toucans.

Order IV. RASORES.

Upper mandible, vaulted; nostrils, pierced
in a membranous space at their base, covered
by a cartilaginous scale. Legs, strong, mus-
cular; three toes before united at their base by
a short membrane, and one behind, higher
than the rest, furnished with short, blunt, and
robust nails, for the purpose of scratching up
the food. Tuil-fea-
thers 14—18.

The food of the
Scratchers, or gal-
linaceous birds, be-
ing vegetable sub-
stances, as grains and
seeds, they have a
large crop and ex- Mes
tremel muscular ;
pera They most- Beak 0f Sit ee
ly deposit and hatch their eggs on the ground
in a rudely constructed nest of straw. Each
male has ordinarily many females, he takes no
part in nidification or in rearing the young;
and these are generally numerous and able to
run about and provide for themselves the mo-
ment they quit the shell.

The families of the Rasores are the Colum-
bide, or Dove-tribe ; Cracide, Curassow-birds ;
Phasianide, Pheasant, common Fowl; Yetra-
onide, Grouse, Partridge.

Order V. CURSORES.

Wings very short, not used for flying; legs
robust; Sternum without a keel.

This order includes the Brevipennes, which
constitute a tribe of Waders (Grallz) in the
Cuvierian system ; and form in the system of
Mr. Vigors, a family of Rasores under the
term Struthionide. They differ remarkably
from one another, both in the form of the beak
and feet, and each known species forms the
type of either a separate genus or family.

Among the Cuculide, the ‘ Traveller’s Friend,* of
South America,’ and among the Psittacide, the
* ground parrots’ of New South Wales, are remark-
able for their preference of the ground, for progres-
sion along which their elongated naked tarsus, and

slender toes, of which one of the hind ones can be ©
brought forward to the front row, favourably adapt
them. ~"*
* The Trichoglossi of New Holland afford as re- —
markable an exception in respect of powers of Aight 5 ‘
for instead of the usual short rounded wings of the
parrot tribe, they have them elongated te pointed
like those of a hawk, and dart through the forests
with inconceivable rapidity. bes nh

AVES.

The Coursers with
a depressed beak have
the longest and strong-
est legs, and run with
remarkable velocity ;
these include

The Ostrich ( Stru-
thio Camelus) which
has only ¢wo toes. QAgC it~
( Fig. 122.) Rh ath

The Rhea (Rhea Ame-» Foot of the Ostrich.
ricana. ) .
which have three
The Cassowary (Cas- toes, all turned for-
suarius galeatus. ) waid
The Emeu ( Dromaius 5
ater. )

Of these four giants of the class the first
inhabits the continent of Africa, the second
South America, the third Java, and the fourth
Australia.

The Coursers, with a compressed beak, are
represented by a single and now extinct genus,
the Dodo, ( Didus ineptus, Linn.)

This bird is known from a description given
by one of the early Dutch navigators, and
preserved in Clusius ( Evoticorum libri de-
cem descr. 1605, pp. 99 and 100); by an oil-
painting of the same period, copied by Ed-
wards (Gleanings, plate 294); from a de-
scription and figure in Herbert’s Some Years
Travels in Africa, Asia, &c. 1677; and from
the Historia Naturalis et Medica, of Jacob
Bontius, 1658.

A foot of the Dodo is preserved in the British
Museum, and a head in the Ashmolean col-
lection at Oxford. The beak resembles that of
the Penguin or Albatross rather than that of
a Vulture, to which it has been compared.
The foot would resemble that of the Apteno-
dytes, if it were webbed, which however it is
not nor has been. It is very similar to, but

roportionally stronger than, the foot of the
ieee. We have examined carefully the
foot in the British Museum, and also the head
of the Dodo at the Ashmolean Museum, and
derived a conviction that they are the remains
of a bird sui generis.

A third form of beak among the Brevipennes
or Cursores is presented by the Apteryx Aus-
tralis ; a bird inhabiting and apparently pecu-
liar to the island of New Zealand. The man-
dibles are elongated and slender, the upper
one is marked on either side by a longitudinal
furrow. The toes are, as in the Dodo, four in
number; but the fourth, or posterior one, is
smaller, being reduced almost to a spur, and
the three anterior ones have the lateral skin,
notched as in the Phaleropes. The wings are
shorter than in any other known bird, are quite
concealed by the feathers, and terminate in a
sharp spine or claw. The feathers are narrow
like those of the Cassowary.

Ordo VI. GRALLATORES.

Legs with the tibia, and especially the me-
tatarsus very long, stretched out behind in
flight; the distal end of the tibia unfeathered ;
toes elongated, straight. Wings long. Body
slender; neck and beak long.

269

Head and leg of the Ibis.

The Waders,—or Gralla, as they were termed
by Linneus from being raised on their long
legs, as on stilts,—frequent for the most part
the banks of lakes and rivers, marshes, and
the shores of estuaries, and derive their food,
some exclusively from the waters, feeding on
small fishes, aquatic mollusks, worms, small
reptiles, and insects, as well as their spawn,
while others are of more terrestrial habits and
food. Of the latter kind are the Gruide, or
Stork tribe, which are chiefly vegetable feeders,
and resemble the land birds in their bill and
feet; the former being more obtuse than in
the typical waders, and the latter shorter. Then
follow the Ardeide, or Heron tribe; the Scolo-
pacide, Snipe, Woodcock ; the Rallide, Rail,
Coot; and the Charadriade, Plover, Sander-
ling, &e.

The Waders are remarkable for their power
of preserving a motionless position upon one
leg for a considerable length of time; the
mechanism by which this is effected will be
afterwards described. During flight they
stretch out their long legs behind to counter-
balance their long neck, and the tail is always
extremely short, its function as a rudder being
transferred to the legs. They mostly make or
choose their nests on the ground, and the young
are enabled to run about as soon as hatched,
excepting in those Waders which live in pairs,

Ordo VII. NATATORES.

Body closely covered with feathers, and
coated with a thick down next the skin. Legs
short, placed behind the point of equilibrium.
Toes united by a membrane or web, which is
sometimes divided.
A The Swimmers, or

We } Palmipedes, are of all
the orders of birds the
most easily recogniza-
ble by the structure and
position of their oar-
like feet: this peculi-
arity which occasionsan
awkward gait on land,.
is extremely favourable
to those birds ‘ whose
business is in the great
waters.” Their body
is boat-shaped, and ge-
nerally elongated, as is

Foot of the Pelican,

270

also their neck. Their dense plumage is oiled
and lubricated by the secretion of the coccy-

geal glands, which are remarkably developed —

for that purpose. In general the males have
many females, and in harmony with this spe-
ciality the young are hatched in a condition
which renders the cooperation of both parents
for their support unnecessary, being able to
take to the water and swim about in search
of food the instant that they are liberated from
the egg-coverings. The families of Swimmers
are the Anatide, Swan, Goose, Duck; Co-
lymbide, Divers; Alcade, Auks; Pelecanide,
Pelican, Cormorant, Gannet ; Laride, Gulls.

1. Osteology.—The skeleton of Birds is re-
markable for the rapidity of its development
and the light and elegant mechanism displayed
in the adaptation of its several parts. The
osseous substance is compact, and exhibits
more of the laminated and less of the fibrous
texture than in the other vertebrate classes.
This is more especially the case in those parts
of the skeleton which are permeated by the air.
The bones which present this singular modifi-
cation havea greater proportion of the phosphate
of lime in their composition than is found in
the osseous system of the mammalia, and they
are whiter than the bones of any other animal.
In the bones where the medulla is not dis-
placed or dessicated by the extension of the
air-cells into their interior, the colour is of a
duller white. In the Silk or Negro-fowl of
the Cape de Verd Islands (Gallus Morio,
Temminck) the periosteal covering of the
bones is of a dark brown, and in some parts
almost black colour; but this ought to be re-
garded as a peculiarity of the cellular rather
than of the osseous texture, which does not
differ in colour from that of other birds;
indeed the thin aponeurosis covering the lateral
tendons of the gizzard of the Silk-fowl is
observed to have the same dark hue as the
membrane which invests the bones.

Although in the disposition of the parts of
the osseous system of birds the plan which
pervades the vertebrate type of structure is
nowhere absolutely violated, yet the variations
from that plan required by the peculiar exigen-
cies of the class are of the most striking and
interesting kind. We shall successively con-
sider the relations of these modifications to
the powers and habits of the bird as they
present themselves in the vertebral axis, in the
bones of the head and thorax, and in those
of the anterior and posterior extremities.

AVES.

The vertebral axis or spine is divisible into a

cervical (fig. 125, a), dorsal (b), sacral (c), and :

caudal (d) region; the vertebrae im

succeeding those which bear ribs havea lateral

anchylosis with the iliac bones, and therefore
there is no part of the spine which possesses
the characters of the lumbar vertebre of mam-
malia and reptiles.

The vertebre are the first parts of the osseous
system which make their appearance in the
development of the embryo, and they are of
all parts of the skeleton the most constant in
their existence and general characters. |

The dorsal or costal vertebre in birds rarely
form more than a fourth part of the entire
vertebral column, and in some of the long-
necked Grallatores, as the Stork, form only
an eighth part of the spine; they have not
been observed to be fewer than six nor more
than eleven in number throughout the class:
the latter obtains in the Swans ( Cygnus canorus
et olor) and Sheldrake; the most common
numbers are seven or eight.

The dorsal vertebre are short, as compared
with the cervical: they appear broad when
viewed superiorly, in consequence of the great
development of the transverse processes; but
their bodies are much compressed in the lateral
direction, so as to be reduced almost to the
form of vertical lamin towards the sacral
region. This is especially observable in the
Penguins (Aptenodytes, Catarrhactes); but
in the Ostrich the bodies of the dorsal ver-
tebre retain their breadth throughout.

The bodies are not united by intervertebral
substances, but by capsular ligaments and
synovial membranes; the anterior articular
cartilaginous surface is convex in the vertical
direction, and concave in the transverse; the
posterior surface is the reverse. The Penguins,
however, present a remarkable exception to
this rule. The posterior surface of the third
dorsal vertebra’ is uniformly concave, to which
the opposed end of the fourth vertebra presents
a corresponding convexity: the ball and socket
joint is continued between the several ver-
tebre to the last dorsal, which is anchy-
losed to the sacrum. This is an interesting
affinity to the Reptilia, inaddition to numerous
others displayed in the construction of these
singular birds. In most birds the bodies of
some of the middle dorsal vertebre are an-
chylosed together; and in general those which
are nearest the sacrum. In the Flamingo we
have observed this anchylosis extending from
the second to the fifth
dorsal vertebra. In the
Sparrow-hawk the second,
third, fourth, and fifth
dorsal vertebree are conso-
lidated into one piece,

while the sixth enjoys con-
siderable lateral motion
both upon the fifth and —
seventh, which last isan- —
chylosed to the sacrum; —
so that the body can be ©

rapidly and extensively in-
flected towards either side ~

AVES.

during the pursuit of prey. This structure
and its uses were first pointed out by Mr.

H. Earle.

The bodies of the anterior dorsal vertebre
send down processes from their inferior or
ventral surfaces for the advantageous origin
of the recti antict majores muscles of the neck.
These processes differ from the inferior spines
of the tail in not being perforated for the
passage of an artery. This part of the spine
is further strengthened by the extension of
osseous splints from the transverse processes,
which unite those of contiguous vertebre to-
gether, and also by the anchylosis of the
spinous processes. But where a similar ne-
cessity for the fixation of the trunk does not
exist, as in the Struthious birds and Penguins,
which cannot fly, all the dorsal vertebre are
moveable upon each other. When it is con-
sidered that the head, posterior extremities,
and viscera are suspended in flight from this
central portion of the trunk, and that it has
almost exclusively to sustain the shock of the
violent contractions of the principal muscles
of the wings, the necessity for the mechanism
consolidating the dorsal vertebre will be readily
appreciated.

_Immobility and strength are still more ob-
viously required in that part of the spine by
~which the weight of a horizontal body is to
be transferred to a single pair of extremities
articulated to the trunk behind the centre
of gravity. The anchylosis of the bodies of
the vertebra, which already begins to appear
in the last dorsal, is, therefore, continued
. through all the sacral vertebra as far as the
caudal region; and this consolidated mass
(6 toc) is united laterally to the iliac bones.
Hence it is always difficult to determine the
number of vertebra of which it is composed.
We have made sections of the sacrums of many
different birds with a view to determine this
fact, and have generally found the number
greater than that which is indicated in the
tables of Cuvier. Thus the Stork has twelve,
instead of eleven sacral vertebre; the Coot
thirteen, instead of seven; the Kingfisher
eleven, instead of eight: while the Ostrich, on
the other hand, has but seventeen, instead of
twenty bones of the sacrum. The bodies of
the sacral vertebra are broad, but shallow, and
towards the tail the floor of the vertebral canal
is formed by a mere lamina of bone : the canal
is remarkably dilated in this part of the spine
for the enlargement of the cord which gives
off the nerves to the posterior extremity. It
is a curious fact that the roots of these nerves
pass out of the osseous canal by separate
orifices, the ganglion on the posterior root
-and the union of the two being external to the
spine. The aspect of all these orifices is la-
teral, in the intervals of the transverse pro-
cesses of the different vertebre, which are not
united together as in the mammalia. The first
four or five sacral vertebre give off two sets
of transverse processes, one ventral, the other
dorsal ; the ventral ones are wanting in the
succeeding four, and then suddenly reappear
to abut against the symphysis of the ilium and

271

ischium, and are so continued double to the
end. The spinous processes which are prin-
cipally developed from the anterior sacral ver-
tebre, give off from their extremities lateral
expansions, which anchylose with the iliac
bones, and form an osseous roof, arching over
and concealing the transverse processes.

The coccygeal vertebre of birds, though never
prolonged into a conspicuous caudal appen-
dage, are in general moveable upon each other,
and are frequently nine in number. With the
exception of the last, they are broad and short
and perforated for the lodgement of the spinal
marrow. With the exception of the last also
they have spines on both the dorsal and ventral
aspects ; and the anterior vertebre have also
transverse processes. ‘The last caudal vertebra
(d, fig. 125) is so singularly shaped, that were
it found alone in a fossil state it would hardly
be recognized as a bone of the spine. It has
no medullary canal and no processes ; but is
compressed laterally and terminates above and
often also below in a sharp edge ; its posterior
extremity is obtuse. It supports the coccygeal
oil-gland, and affords a firm basis to the tail
feathers, which, from their use in guiding the
motions of the bird through the air, Linneus
termed the rectrices.*

In the Toucan the three last caudal vertebree
are anchylosed together; the six anterior ones
are articulated by ball and socket joints, the
ball and the socket being most distinct in
the two last of these joints; that between the
sixth and seventh vertebre is provided with a
capsule and synovial fluid, the others have
a yielding ligamentous mode of connexion.
The spinous processes of these vertebra, both
superior and inferior, are of moderate size, but
smallest in the sixth, where the greatest degree
of motion takes place; the transverse pro-
cesses on the contrary are large and broad
so as almost to preclude lateral motion. We
have given a more particular description of
these vertebree because of the singular move-
ments observable in the tail of the Toucan ;
it can be inflected dorsad till the superior
spines of the vertebrae are brought in contact
with the sacrum; and in the performance of
this motion the lateral muscles, which at first
tend rather to oppose the elevators, become, at
a certain point of inflection dorsad of the centre
of motion, elevators themselves, and thus com-
bining with the elevators jerk the tail upon the
back; it is thus that the tail turns as if ona
hinge operated upon by a spring.

As the prehensile functions of the hand are
transferred to the beak, so those of the arm
are performed by the neck of the bird; this
portion of the spine is therefore composed of
numerous, elongated, and freely moveable ver-
tebre, and is never so short or so rigid but that
it can be made to apply the beak to the coccy-
geal oil-gland, and to every part of the body
for the purpose of oiling and cleansing the
plumage. In birds that seek their food in

* In the tail-less variety of the common Fowl
the coccygeal vertebra have degenerated into a
single unshapely knotty process,

272 AVES.

water it is in genera) remarkably elongated,
whether they support themselves on the surface
by means of short and strong natatory feet, as
in the Swan, or wade into rivers and marshes
on elevated stilts, as in the Crane, &c.

The articular surfaces of the bodies of the
cervical vertebre, like those of the dorsal series
above mentioned, are concave in one direction
and convex in the other, so as to lock into each
other, and in such a manner that the superior
vertebrae move more freely forwards, the middle
ones backwards, while the inferior ones again
bend forwards ; producing the ordinary sigmoid
curve observable in the neck of the bird.

This mechanism is most readily seen in the
long-necked waders which live on fish and
seize their prey by darting the bill with sudden
velocity into the water. In the common Heron,

for example, ( Ardea cinerea.) the head can be.

bent forward on the atlas or first vertebra, the
first upon the second in the same direction,
and so on to the sixth, between which and
the fifth the forward inflection is the greatest ;
while in the opposite direction these vertebra
can only be brought into a straight line. From
the sixth cervical vertebra to the thirteenth the
neck can only be bent backwards; while in
the opposite direction it is also arrested at a
straight line. From the fourteenth to the
eighteenth the articular surfaces again allow
of the forward inflection, but also limit the
Opposite motion to the straight line.

Two transverse processes are ordinarily con-
tinued from the anterior part of the bodies of
the cervical vertebre : the inter-space of these
is filled up externally to the vertebral artery
by a rudimentary styliform rib, which is sepa-
rated in the young bird, but afterwards anchy-
losed, and directed backwards parallel to the
body of the vertebre. These processes give
attachment to numerous muscles of the neck,
and being, with the transverse processes, more
strongly developed in the rapacious birds, give
a greater breadth to the cervical region in that
order.

The superior spinous processes are but
feebly developed ; they are most distinct on
the vertebre at the two extremities of the
cervical portion of the spine. Inferior spinous
processes are also found on the vertebre at
the commencement and termination of the
neck, but are wanting im a great proportion of
the intermediate cervical vertebre.

The atlas is a simple ring. In general it
is articulated with the occipital tubercle by
a single concave facet on the body; but in
the Penguin and Ostrich there are two other
facets, continuous with the middle one, but
corresponding with the anterior articulating pro-
cesses of the rest of the vertebra and applied to
the condyloid portions of the occipital bone,
while the middle facet is articulated to the ba-
silar portion as in other birds. The body of
the dentata is joined to the atlas by a single
synovial capsule, its odontoid process is tied
down by a strong transverse ligament stretched
above it, and by a longitudinal one extending
from its extremity to the posterior part of the
occipital condyle. In the articulations of the

bodies of the remaining cervical vertebra

moveable inter-articular cartilage is found in-

closed between reduplications of the synovial
membrane, as in the joint of the lower jaw in
mammalia. The articulations of the oblique
processes have no peculiarities worthy of no-
tice.

A remarkable difference is found in the
diameter of the spinal canal contained in the
cervical vertebre. If, e.g. the sixth cervical
vertebra of a Stork be sawed down verti-
cally, the antero-posterior diameter is greatest
in the middle, least at the ends; but if it be
sawed lengthwise horizontally, the transverse
diameter is the reverse, being narrowest at
the centre and widest at the ends. In the
Ostrich, the Swan, and many other birds the
spinal canal is widened in every direction at
the extremities of the vertebre; and on the dor-
sal or posterior aspect of the spine, the canal
remains open for some extent in the intervals of
the vertebre, the cord being there protected
only by membrane and the elastic ligaments
which connect the roots of the spinous pro-
cesses together. The final purpose of this
structure has been ably illustrated by Mr. Earle
in the Philosophical Transactions, (1822, p.
276.) where he shews that it is adapted to pre-
vent a compression of the spinal cord during
the varied and extensive inilections of the neck.

The vertebre of the different regions of the
spine bear a different proportion to each other
in respect to number among birds, from what
we observe in the mammalia and reptilia. The
cervical portion in this class is generally com-
posed of a much greater number of vertebre
than any of the other divisions of the spine;
in this respect the fossil reptilian genus called
Plesiosaurus alone resembles the bird. This
singular animal was an inhabitant of the
waters, and it is interesting to observe that
the peculiarity which distinguishes it, viz. the
great length of neck, is chiefly characteristic
of the Aves aquatice of Nitzsch. In the Gral-
latores the length of the neck is determined by
the height of the legs : in the Natatores it is
necessary for the purpose of obtaining their
food while swimming the waters. The dorsal
vertebree are usually less numerous than in
mammalia. The caudal vertebre are subject
to few variations; they never project in the
form of a tail, but are most numerous in those
birds which make the greatest use of the tail-
feathers, as in the Swallows, to direct their
rapid flight, and in the Woodpeckers, where
they serve as a prop or climbing pole.

The following table, which, with some cor-
rections, is extracted from Cuvier’s Legons
d’Anatomie Comparée, exhibits the variety
that exists with respect to the number of ver-
tebre in different species of birds.

Table of the number of vertebre in birds.

Order. Raprores Vertebre.
Species.
Vulture ...... 13 7 11 7
RBagle 505. 0a) 8 8 11. 8
Osprey ...... 14 8 11 7
Sparrow-hawk.. 11 8 11 8

4

Sheers 2d >

Cervical. Dorsal. Sacral. Caudal. 4

AVES.

5 Cervical. Dorsal. Sacral. Caudal.
Bagzard «1000 h4 7 10 8
Rite oi. tiseias 12 8 11 8
Great Horned
Owl 1.38 te ceaas 7 12 8
Hawk-owl .... 11 8 11 8
Order. INsEssores.
Flycatcher .... 10 8 10 8
Black-bird .... 11 8 10 7
Tanager ,..... 10 8 9 8
MO cake. 13 8 13 7
PGGC cise. 18 8 13 8
Ae © 7 11 8
Starling ...... 10 ni 1g 9
Gross-beak.... 10 7 12 7
etna inn. 6 11 6
parrow...... 9 9 10 7
Goldfinch .... 11 8 11 8
Titmouse .... 11 8 11 7
SE & | 9 10 7
Redbreast .... 10 8 10 8
Swallow...... 11 8 11 9
Night-jar .... 11 8 11 8
Humming-bird 14 9 10 8
Hoopoe..,... 12 7 8 7
King-fisher .... 12 7 11 7
Order. Scansores.
Woodpecker .. 12 8 10 9
Toucan (Ariel) 12 8 12 9*
PaO aewsccx>s 21 9 11 8
Order. Rasonres.
Pigeon :..... 13 7 13 7
Peacock...... 14 7 12 8
Pheasant...... 13 7 15 5
Turkey ...... (15 7 10> '-8
Crested Curas-
Sow ieeesscs 15 8 10 7
Order. Cursores.
MIME \a'cscee,, 18 10 17 9
Cassowary.... 16 10 19 7
GR inns es. 14 9 4 2
Emeu........ 19 9 19 9
Order. GRALLATORES.
PM wc ascee 18 7 10 x
POPE, ap escee , 19 4, 12 8
Crane......,. .19 9 12 7
Shaipasnes . 24 a 13 fi
Spoon-bill.... 17 7 14 8
PUNE Ca serc, 14 9 10 8
PUNO vce cs... 45 8 10 7
Lapwing...... 14 ee 40
Wood-cock.... 18 7 13 8
Curlew ...... 13 8 10 8
Oyster-catcher.. 12 9 15 7
Bad 6-aetek 3 8 13 8
COO Sale e as 10 13 Biri
ween a 8 13 7
Flamingo .... 18 ts a A

* Cuvier says “‘ plus de 7: ” we have ascertained
the above number in a dissection of a recent spe-
cimen of this singular genus ( Rhamphastos Ariel,
Vigors) Zool. Proceedings, vol. 11. p. 42.

+ This part of the spine is singularly modified
and interrupted bya natural atrophy of many of
the vertebra.

VOL. I.

273

Species. Cervical. Dorsal. Sacral. Caudal
Order. Naratores.
Pelican ...... 16 7 14 z.
Cormorant.... 16 9 14 8
fe ee rae, F 8 10 8
ae anedae 202 8 11 8
je Serene neta ¥ 9 13 9
Catarrhactes ... 13 9 13 8
SWORciwedanees sie 11 14 8
RUGS 16 a'ntasatvass eal 10 14 7
Barnacle. .....-.18 10 14 9
Ae eee eee, P 8 15 8
Sheldrake .... . 16 11 11 9
POORER et cits wes sh 9 14 7
Merganser.... 15 ‘8 13 7
Grebe...e0.... 14 10 13 7

The skull in all the Vertebrated Classes is -
composed of a considerable number of osseous
pieces, which, in the Mammalia, unite in defi-
nite numbers and proportions, so as to form
the bones termed occipital, temporal, sphenoidal,
&e. In the cold-blooded Vertebrata the com-
ponent parts of these bones generally remain
separated throughout life, giving an appear-
ance of great complexity to the skull, and occa-
sioning much difficulty in tracing their cor-
respondence with the cranial bones of the
higher classes. Equal difficulty is experi-
enced in determining the component parts of
the head in Birds, but from a very different
cause. In the cold-blooded Crocodile, and
Fish, this difficulty is caused by the tardiness
of ossification, which prevents the coalition of
the several elements of the cranial bones into
their determinate groups; while, in Birds, the

Fig. 126.

Skull of a young Ostrich.

274

energetic respiratory and circulating functions
Occasion so rapid an evolution of the osseous
system, that the bones of the cranium become
at an early period anchylosed into one pits,
with a total obliteration of the original har-
monix; it is necessary, therefore, to examine
the skull of the Bird at an early period of ex-
istence, and to compare it with the foetal con-
dition of the skull of the Mammal, when it will
be found to be ossified from analogous centres,
which, in their expansion and subsequent
union, obey the same laws of, as it were,
elective attraction.

The occipital bone is originally composed
of four pieces: the basilar, below, (a, fig. 126,)
the two condylovid, laterally, (b, b,) and the
expanded spinous process, or supra-occipital

iece above (c). These fulfil the usual
fanetions of the occipital bone, protecting the
cerebellum and medulla oblongata, and form-
ing the medium of connection between the
cranial and cervical vertebrae.

The head is articulated to the spine by
means of a single hemispherical tubercle (z,
Jig. 126,) which plays in a corresponding
cavity of theatlas. In most birds the tubercle
is formed exclusively by the basilar piece of
the occipital bone, but in the Ostrich and
Penguin the condyloid portions also contribute
to its formation, which is an approximation to
the structure of the occipital condyle in the
Chelonian reptiles. In all birds, however, the
articulation is such as to allow of a much greater
extent and freedom of motion to the head than
exists in the Mammalia.

The temporal bone consists of the petrous por-
tion, the squamous portion, (d, d, fig. 126, 127)
and the tympanic bone, or os quadratum (e. )
The petrous bone includes the complex parts
of the internal ear, and is soon anchylosed to
the condyloid portions of the occipital bone,
which fulfil the functions of the mastoid pro-
cesses. ‘The squamous, or, as it may be termed,
the zygomatic portion of the temporal bone (ad)
remains for a longer time separate; it forms
the lateral boundary of the cranial cavity, as in
quadrupeds, and the tympanic element is move-
ably articulated to its inferior part.

The parietal bones (f, f, fig. 127) retain
their separated condition till after the union of
the occipital pieces, they then unite and protect
the posterior part of the cerebral hemispheres.

The sphenoid bone is composed of a basilar
portion, (g, fig. 126,) two orbital plates, (h, Jeg.
127,) forming the floor and part of the septum
of the orbits, and which rapidly anchylose with
the preceding; two cranial portions, or ale ma-
jores, (g, fig. 127, 128,) which remain longer
separate, and form the posterior part of the or-
bits, and two pterygoid portions (‘interarticular’
or ‘omoid’ bones), (i, i, fig. 126,) which, in
birds, abut against the tympanic or quadrate
bones. The great ale of the sphenoid join the
parietal, and separate the temporal from the
frontal bones.

The frontal bone (k, fig. 127) continues for
a longer period than the parietal to be sepa-
rated into two lateral halves by the continuation
of the sagittal suture through its whole length.

AVES.

The ant-orbital

processes (13,

Jig. 127) are

elongated and
}d pointed, ex-
tending for
wards to join
the lachrymal
bones, (0, 0,
Jig. 127,) con-
siderably
yond the ori-
gins of thenasal
bones, and are
separated from
each other by
these and by a
process of the
ethmoid bone,
The post-orbi-
tal processes
are most de-
veloped in the
Parrots and
Maccaws, in
the latter of

ST which they join
Skull of a young Ostrich. the lachrymal
bones, and complete the bony circumference
of the orbits, (fg. 128.) In the Emeu they
remain for a long time distinct bones, as in the
reptiles. The frontal bone thus forms the
whole of the superior, and, more or less, of the
outer boundary of the orbits, and protects the
anterior part of the cerebrum. It supports
the horn-like prominences which are seen upon
the heads of the Cassowary, Pintado, and Cu-
rassow, the bony bases of which commence by
distinct ossifications.*

A small part of the ethmoidal bone (4,
Jig. 127) is seen, in the Ostrich, on the ex-
terior of the cranium lodged between the
ant-orbital processes and nasal bones (n, n.)
The ethmoid separates, as usual, the orbits from
the cavity of the nose, and forms a great part of
the inter-orbital septum where this exists, as
in the parrots, (m, fig. 128.)

In the mature bird the whole of the prece-
ding bones, with the exception of the tym-
panic elements of the temporal bone, are
usually found anchylosed into one piece.

The internal surface of the cranium exhibits
a well-marked transverse ridge, which divides
the cavity into two principal depressions.
In the anterior division the hemispheres of

* « A most remarkable sexual difference appears
in the skull of the crested Hens: in these the frontal
portion of the cranium is dilated into an immense
cavity, on which the crest of feathers is placed.
This degeneracy of the formative impulse, which
is propagated to the offspring, is quite unparalleled
in the whole animal kingdom: I have ately ex-
amined several heads of such hens in a fresh state,
and have found that this peculiar dilatation of the
cranium is filled by the hemispheres of the cere-
brum, and is separated from the posterior part
which holds the cerebellum, as in the common
hen, by an intermediate contracted portion,’—Law-
rence’s Blumenbach’s Comp. Anat. p. 61.

}
rs
j
Al
pA

=e

AVES.

the cerebrum are lodged, the rest of the brain
is contained in the posterior division. The
relative proportion of these divisions varies in
the different orders; in the Insessores and Ac-
cipitres the anterior superior depression is the
largest; in the Rasores, the posterior inferior
depression equals, and in some species, ex-
ceeds the former in size. The orbits form two
slight projections in the anterior fossa of the
cranium, which is partially divided longitu-
dinally by a ridge corresponding to the inter-
ae of the cerebral hemispheres. This is
leveloped in the Gallinaceous birds into a
thin falciform osseous crest, which is especi-
ally remarkable in the Partridge, Turkey, and
Capercailzie. It is also well developed in the
Parrot tribe. The sella turcica in all birds is
a deep round cell, lodging the pituitary gland,
as in the Mammalia.

The foramen magnum (1, fig. 126) is formed,
as usual, by the union of the four pieces of the
occipital bone: its size is considerable, having
relation to the mobility of the cranium upon
the spine. The foramen lacerum posterius
(2, 2, fig. 126) is situated immediately below
the membrana tympani (8, 8, fig.126.) There
is no fissure analogous to the foramen lacerum
medius. The carotid foramina (3, 3, fig. 126)
are transversely oblong, and situated on the
body of the sphenoid; the same bone, in the
Ostrich, is perforated immediately anterior to
the carotid canal by the Eustachian tube, (4, 4.)
The posterior palatine foramina are wide spaces,
(5, 5,) separated from each other by the vomer
(4% fig. 126). Anterior to these, in the base
of the skull, are seen the still wider posterior
apertures of the nostrils (6, 6). In the inside
of the cranium the internal auditory foramina
are distinctly seen. ‘The foramen lacerum an-
terius is divided into several distinct foramina.
The optic foramina, on the contrary, are closely
approximated, and frequently blended into one.

e olfactory nerves escape each by a single
foramen, and are continued to the nose either
along a deep groove on the upper part of the
orbital septum, or, as in the Toucan, pass
through a complete osseous canal.

‘The bones of the face correspond in number
and relative position with those of the Mam-
malia, but differ considerably in their forms
and proportions; they bear most resemblance
to the facial bones of the Rodentia. They are

always moveably connected with the bones of
the cranium, and retain much longer than
these their separate condition.

Fig.

The nasal
bones (n, n,
fig. 127, 128)
are a_ large
and elongated
pair, extend
ing from the
inner side of
the ant-orbital

processes of
Skull of a Parrot. the frontal to

the outer side of the ascending processes of the
intermaxillary bones, expanding as they ad-
vance forwards, and giving off from their outer

128.

275

sides a process which curves downwards to
join the superior maxillary bone, to which it
has erroneously been considered to belong.
The nasal bones soon anchylose with the
frontal, ethmoidal, inter-maxillary, and superior
maxillary bones.

The lachrymal or ungueal bones (0, 0, fig. 127,
128, 1, fig. 125) are also of considerable propor-
tionate size. They are more exposed than in mam-
malia, and are usually moveably articulated by
their mesial or anterior edge to a varying number
of the bones of the skull. These are commonly
the frontal, nasal, and malar bones; but in the
ostrich the lachrymal articulate with the palatine
bones; in the Parrot they extend backwards
beneath the orbit to the post-orbitals, and thus
complete the bony circumference of that
cavity, while in the Owls they do not at all
articulate with the frontal bone. They are
smallest in the Rasores and Natatores,and attain
their greatest development in the diurnal Rap-
tores. In these the separated supra-orbital
bones give additional protection to the eye,
over which they form, in conjunction with the
lachrymal, the projecting arch so characteristic of
the physiognomy of the bird of prey.

The palatine bones ( p, p, fig. 126,) are of great
proportional size: each is of an elongated,
slender, depressed figure, becoming narrower
anteriorly, forming the posterior part of the pa-
latine arch, and completing with the vomer the
boundary of the posterior nostrils. In the Rap-
tores the palatine bones are united together
only by a small part of their anterior extre-
mities. In the Owls the posterior extremities
are widely separated from each other. In
the Insessores they are not united together in
any part of their extent, except in the Gross-
beak, ( Lovia Coccothraustes,) at the anterior
extremity. In this bird and in the Parrots, the
palatine bones have not a horizontal but a ver-
tical position, contrary to what they are in
most other birds. They are least developed
in the Rasores.

Thevomer (q, fig. 126) is rapidly anchylosed
in the Ostrich with the sphenoid, appear-
ing asa long, moderately compressed, pointed
process, extending forward from the spine of
the sphenoid in the interval of the palatine
bones, and dividing the posterior aperture of
the nose into two lateral halves. In most other
birds it remains distinct from the spine of the
sphenoid, as it is also in the ostrich at a very
early period.

The intermazillary bone (m, fig. 125, r, 7,
Jig. 126, 127, 128) determines the form, and
constitutes the greater part, of the upper man-
dible. It consequently presents considerable
variety in its figure and proportions, and also
in its mode of articulation, in different birds ;
but in every species it is of considerable size.
When completely ossified, which it is at
a very early period, the intermaxillary bone
consists of three processes which diverge from,
or unite to form, the extremity of the upper
mandible: the superior mesial process or nasal
plate is lamellate, depressed or flattened hori-
zontally, extends backwards between and above
the lower ends of the nasal bones, and becoming

T2

276

wedged, as it were, between their upper ends, is
articulated in general by an anchylosis to them
and the ethmoid bone. This union, however,
always allows of a certain elastic or yielding
motion to pressure from below. In the Parrots,
where the upper mandible is an important in-
strument in their climbing habits, the nasal plate
of the intermaxillary bone is joined to the cra-
nium bya ligamentous substance (11, fig. 128).
The two lateral or mandibular processes (1, 7,
Jig. 127) of the intermaxillary bones diverge and
extend backwards, external and superior to the
superior maxillary bones ; and, in the Ostrich,
they articulate with the anterior extremities of
the malar or zygomatic bones. Throughout
their whole course the mandibular processes
are in close contact with, and soon become an-
chylosed to the superior maxillary bones. The
ossification of the intermaxillary bone obeys the
ordinary law of centripetal development. The
lateral moieties are still separate in the chick
at the conclusion of incubation; and in the
duckling they do not anchylose until six weeks
after that period. The union commences at
the anterior extremity, while at the opposite
or cranial end of the nasal process, traces of the
original separation may frequently be observed
in the full-grown bird; these are very con-
spicuous in the Gulls, ( Laride ).

The superior mazillary bones (s, 8, fig: 126,
127) are very seldom united together in birds.
They are comparatively of small size. Each
may be said to commence mesiad of the ori-
gin of the mandibular processes of the in-
termaxillary bone; it then expands as it pro-
ceeds backwards, and, opposite the anterior
end of the palatine bone, divides into two
processes. The mesial or palatine process ex-
tends along the outside of the palatine bone,
and soon becomes anchylosed to it; the ex-
ternal or malar process is articulated obliquely
to the under part of the anterior moiety of the
zygomatic bone. At the origin of this process
a small projection meets the descending pro-
cess of the nasal bone. In most Gallinaceous
birds, the body, or part anterior to the palatine
and zygomatic processes, is wanting; but in
the common fowl it extends towards the
mesial line, and unites with the vomer, so as
to divide the palatal fissure into an anterior
and posterior cavity. In the Ostrich, where
the body of the upper maxillary extends for-
wards to the symphysis of the intermaxillary
bone, a process is also given off at the origins
of the palatine and zygomatic bones, which
passes inwards to the vomer, and completes,
in the adult, the boundary of the anterior pa-
latal fissure.

The movement of the bony framework of
the upper mandible resulting from the union
of the intermaxillary, superior maxillary, and
palatal bones, is immediately effected by the
elongated malar or zygomatic bone, (9, fig. 125,
t, t, fig. 126, 127, 128,) which transfers to
the zygomatic process of the superior maxil-
‘lary the movements of the tympanic bone,
being so placed as to form the medium of
communication between these parts. It ex-
tends in a straight line from one to the other,

AVES.

this being the form best adapted to resist the
pressure upon its two extremities. With the
superior maxillary bone it is soon anchylosed, —
but with the tympanic bone it is in most Birds

articulated by a moveable ball and socket-joint,
the articular surfaces being connected by a_
fibro-cartilaginous substance; in the Capri-

mulgi, however, it is anchylosed at both ex-

tremities. The malar bone is commonly of a

compressed or vertically flattened form, but

sometimes, as in the Ostrich, it is cylindrical.

It is originally composed of two pieces placed
in a parallel line, one above the other > the

superior being pointed at both extremities,

and much smaller than the other.

The tympanic, pedicellate, or quadrate bone
(i, fig. 125, e, fig. 126, 128,) is never anchy-
losed with the other elements of the temporal
bone, but is freely moveable as in most of the
cold-blooded ovipara; and it is interesting to
observe that in the rodent quadrupeds, which
exhibit many other affinities to birds, the tym-
panic element remains for a long period a de-
tached bone, but is situated altogether posterior
to the maxillary articulation. In birds, where
the base of the cranium is remarkably shortened
in the antero-posterior diameter, the tympanic
bone is, as it were, thrust forward and wedged
in between the inferior maxillary bone and the
zygomatic process of the temporal, thus inter-
cepting, and articulating with, both the lower
jaw and cheek-bones. The membrana tympant
continues, however, to be attached by about half
its circumference to the posterior part of the os
quadratum, and for the remainder of its extent
to the occipital and sphenoidalt bones.

The upper end of the tympanic bone is
articulated by two distinct transverse condyles
with the zygomatic portion of the temporal
bone; below these it is contracted, and then
expands as it descends, giving off a strong
process from the middle of its anterior surface,
which projects into the orbit, then a smaller
process from its posterior surface extending
backwards, and lastly, sending off at its lower
extremity an external process for the malar
bone, and an internal one for the pterygoid,
between which processes are two oblique oblong
convexities for the articulation of the lower jaw.

Having an immediate connection with the mo-
tions of the whole beak, it necessarily presents
varieties of form in different birds, without,
however, losing the characteristic figure which
has been described. By whatever cause the
tympanic bone is carried forwards, whether
by the action of the pterygoid muscles in-
serted into its orbitar process, or by the pres-
sure of the lower jaw upon its inferior surface,
that motion is communicated to the pterygoid
and malar bones, which transfer it, the one
to the palatine, the other to the superior max-
illary bones, and thus the upper mandible
is elevated at the same time that the lower
one is depressed. The elasticity of the union
of the nasal process of the intermaxillary
bone with the cranium restores the upper
jaw on the cessation of the pressure fro
below, to the position from which the move-
ment of the tympanic bones had displaced it.

Ee eE—EEE——E——EE——

eC

AVES. 277

These movements are freely allowed in most
birds from the nature of the articulation of
the tympanic bone; but in the Struthious birds
they are more restrained, from the connection
of the bone with the descending zygomatic
process of the temporal bone; the extent of
this attachment is greatest in the Emeu, where
it almost produces a complete fixation of the
tympanic bone.

e inferior maxillary bone (p, fig. 125, v,
Jigs. 126, 128,) is originally composed of twelve
distinct pieces, each lateral moiety being made
up of six. The anterior symphyseal or dental
portion of each ramus first unites with its
fellow at the symphysis; the two portions
which form the condyle (v, fig. 126) next an-
chylose; the angular (v, fig. 126), supra-
angular and opercular, or splenial pieces are
consolidated at a later period. The anterior
extremities of the angular and supra-angular
pieces are wedged into corresponding grooves
of the symphyseal element; and the opercular
portion is extended like a splint along the
inner side of the gomphosis, by which the
preceding portions are united.

The traces of the original separation of these
bones long remain in the semi-aquatic and aqua-
tic birds ( Grallatores and Natatores ), which,
as the lowest of the class, manifest their affinity
in this respect to the cold-blooded Ovipara,
where this complex structure of the lower jaw
continues throughout life.

As the lower jaw, thus constituted, forms
with the upper jaw the principal organ of pre-
hension in birds, it presents many variations
of form and magnitude, which immediately
relate to, and are consequently indicative of
their mode of life, food, &c. These general
modifications will be treated of in relation to
the digestive function, but some of the less
conspicuous characters of the lower jaw may be
more appropriately considered in this place.

rami are in general completely anchylosed
at the symphysis, the extent of the united por-
tions varying considerably in different birds,
but occupying in most cases only a small pro-
portion of the jaw. In the Pelicans the rami
are united by the mere extremities, appearing as
if bent upon each other at the symphysis, and
supporting the dilatable sac which fills up the
intermediate space, like the hoop of the fisher-
man’s landing-net. The symphysis is also of
very small extent in most other Palmipeds.
It is small in the Rasores and Cursores. In the
Storks and Cranes it extends along a third part
of the entire jaw. In the Flamingo, where the
anterior part of the jaw is bent down at an
obtuse angle, nearly half of the rami are
united. In the Skimmers ( Rhyncops ), Horn-
bills, and Toucans, two-thirds. In the Curlew
the two rami are in apposition for two-thirds
of their anterior extent, but are not anchy-
losed, and form, in this respect, the only
known exception to the rule.

In diurnal Birds of Prey, in many of the
Parrot-tribe, in the Herons and Swans, each
ramus of the lower jaw forms an entire bony
plate. In the rest of the class a membranous
unossified space is left at the place of union

of the symphyseal with the angular, supra-
angular, and splenial elements. This defi-
ciency is of a longitudinal form, and is always
situated behind the middle of the ramus.
In the Bustards, Woodcocks, Curlews, Gulls,
Skimmers, Guillemots, Petrels, and Pen-
guins, there is a second foramen, of a rounder
figure, posterior to the preceding, and resulting
from a defective union of the angular, supra-
angular, and condyloid pieces. In the Casso-
wary this space is subdivided into several
small foramina. In the Emeu ( Dromaius.) and
Ostrich ( Struthio) there is a single small fora-
men at the corresponding part.

At the posterior part of each ramus the fol-
lowing processes are developed in various
degrees in different birds. The suprangular
piece ascends in a greater or less degree in
the form of a thin lamina with a gently rounded
Outline, representing the coronoid process.
From the inner side of the condyloid piece
there extends a more marked process, which
may be called the internal angular ; and from
the posterior part of the ramus a third process
is continued, which may be termed the posterior
angular process.

The coronoid process is most developed in the
Parrots, Gulls, Herons, and Cross-bills ( Lozia ),
in some of which, as the Lowia coccothraustes,
cardinalis, and pulverulentus, the lower jaw
presents the following peculiarity. A large
sesamoid bone of a triangular form, but
rounded and transverse, with the base directed
outwards and the apex inwards, is situated
at the posterior and internal aspect of the
articular ligament of the lower jaw. It com-
pletes the maxillary articulation posteriorly, and
corresponds by its anterior articular surface to
the posterior part of the outer condyle. Thear-
ticular surface of the lower jaw of the Parrots
is a simple narrow longitudinal furrow, open at
the two extremities. That of the Toucans is
almost equally simple, but of a rounder figure.
In most other birds the articular surface is
divided into two distinct portions, of which
the internal is an oblique concavity, the exter-
nal also oblique, but terminating in a convex
eminence behind.

In the Rasorial birds the coronoid process is
feebly developed, but the internal and angular
processes are of large size. The latter is very
remarkable in the great Cock of the woods,
( Tetrao urogallus,) where it extends upwards
and backwards in a curved form for the extent
of an inch, affording attachment to the power-
ful muscles required to produce the wide ex-
paneer of the mandibles necessary to seize the
arge fir-cones which constitute its food. In
the lamellirostral Palmipedes not only are the
internal, and the posterior angular processes of
large size, but there are also two eminences for
muscular attachment on the outer side of each
ramus anterior to the articular surface. In the
Gulls an oblique ridge is continued from a
single eminence similarly situated.

The articular capsule of the lower jaw is
strengthened by ligamentous fibres arising
from the lower extremity of the Re ei
bone, and passing backwards to be inserted into

278 AVES.

the outer side of the internal angular process.
This ligament assumes a fibro-cartilaginous
structure at its anterior part: it is attenuated
internally, and is situated between the two
bones in the outer part of the capsular ligament.
At the posterior part of the joint a strong
fibrous band extends from the end of the mas-
toid process to the internal angular process of
the lower jaw, so as to restrain the forward
movement of the jaw.

The skull presents fewer varieties of form in
birds than in any other class of vertebrate ani-
mals. With the exception of a few species, in
which the beak assumes what may almost be
termed a monstrous development, it has the
form of a pretty regular five-sided pyramid, of
which the occiput forms the base, and the an-
terior extremity of the beak the apex.

The posterior facet or base of the pyramid
is formed by the upper and larger portion of
the occiput, together with part of the temporal
bones. It is the smallest facet of the head,
and is larger in the transverse than the vertical
diameter. It presents the vertical prominence
corresponding to the narrow cerebellum, which
is separated by a venous foramen and furrow
(8, fig. 126) from a broad muscular depression
on either side; below these are the large occi-
pital foramen, (1, fig. 126); the hemispheric
tubercle, which unites the head to the atlas ;
and on either side of this tubercle a smaller
muscular depression, separated by a transverse
ridge from the larger one above, and _per-
forated by the pneumogastric and hypoglossal
nerves; these depressions are bounded laterally
by the mastoid processes. (10, 10, fig. 126.)

The inferior facet or base of the skull joins

.the posterior and lateral facets almost at a
right angle. It is bounded anteriorly and at
the sides by the lower jaw, which, on account
of the compressed form and divarication of the
rami, scarcely intercepts any part of the view
of this very complicated surface. The occipital
condyle, with the muscular depressions on
either side and the mastoid processes, may be
considered in some, and more especially in the
Struthious birds, as forming part of the base of
the skull. Anterior to the basilar portion of
the occiput comes the body of the sphenoid,
which in the Struthionide sends outwards and
forwards two rounded processes (jj, fig. 126)
to abut against the flattened pterygoid bones.
Between the origins of these, and anchylosed
to the spine of the sphenoid, the vomer extends
forwards to a distance varying in different birds.
The tympanic bones are seen on either side of
the body of the sphenoid, and external to these
the zygomatic processes of the temporal ; the
space circumscribed by these bones, with the
mastoid processes behind, forms the expanded
external passage of the ear, which is closed in
the recent state by the large convex membrana
tympani, (8, 8, fig. 126.) Anterior to the
tympanic bones the pterygoid processes (3 i,
Jig. 126) extend forwards and inwards to join
the palatine bones; which are then continued
forwards to the superior maxillary, leaving
between them the large posterior nasal fissure
divided longitudinally by the vomer. These

fissures are commonly continuous with the
anterior palatal fissure, (7,7, fig. 126,) but in
the full grown Struthious and some Gallinaceous
birds, the palatine and maxillary bones unite
with the vomer and separate the two fissures,
thus increasing the bony floor of the nasal
cavities. External to the rami of the lower
jaw, the malar or zygomatic bones may in ge-
neral be seen converging from the tympanic to
the superior maxillary bones, the elongated
triangular space between these bones and the
pterygoid and palatine leads directly from below
into the large orbits.

The two lateral facets present posteriorly the
tympanic or auditory cavity, (8, fig. 128,) ante-
rior to which is the tympanic bone, with the
malar and inferior maxillary bones extending
forwards from its lower extremity. Above the
tympanic bone is the zygomatic process of the
temporal, (d, fig. 128,) arching over it in the
Struthious and Psittaceous birds, as if to effect
its normal connection with the malar bone.
Between the zygomatic and post-orbital pro-
cesses is the crotaphyte depression, (g, fig.128,)
always well-marked, but bounded by ridges
more or less developed in different birds. At
the lower part of this depression may be per-
ceived the large foramen common to the supe-
rior and inferior maxillary divisions of the trifa-
cial nerve. Then come the spacious rounded
orbits, bounded above by the supra-orbital
lamella, behind by the sphenoid and frontal ex-
pansions, which form, at the same time, the an-
terior walls of the cranium; separated from each
other, but always more or less incompletely, by
the thin sphenoidal and ethmoidal plates, the
deficiencies of which are supplied in the recent
state by aponeurotic membranes, and defended
anteriorly by the largely developed lachrymal
bones and the ethmoidal ale, between which
there are always present apertures varying in
size. The pterygoid and palatine bones, with
the styliform malar bone, form a very incom-
plete floor of the orbit.

Anterior to the orbits the sides of the skull
become gradually narrower to the end of the
beak ; between the lachrymal and the superior
maxillary bones a large triangular or rounded
space is left, (11, fig. 128,) which conducts to
the nasal cavity. A second vacancy occurs,
anterior to this, bounded by the nasal, superior
maxillary, and intermaxillary bones, forming
the osseous boundary of the wide external
nostrils. (12, figs. 127, 128.)

The superior surface of the cranium is gene-
rally convex in relation to and indicative
of the development of the brain; it is round-
ed posteriorly, where it is generally widest.
Here on each side is seen the temporal de-
yapsd the interorbital space in the Gulls,

etrels, Albatrosses, Penguins, and other sea-
birds, presents also two depressions, scarcely
less marked, of a semilunar form, the convexi-
ties meeting in the mesial line, and lodging a
gland, whose secretion is carried into the nose
to lubricate the pituitary membrane. Slight
traces of these glandular depressions may be
seen at 13, fig. 127, in the Ostrich. In other
birds the interorbital space is moderately con-

.

‘of ossification.

AVES. 279

cave or flattened. Anterior to this part the
cranium in the Parrot presents the moveable
junction of the upper mandible, but in other
birds a continued osseous surface converges
more or less gradually to the end of the beak,
only interrupted by the anterior orifices of the
nasal cavity.

The skull in the Raptores, especially in the
nocturnal division, is short, broad, and high, in
peryetion to its length, and the cranium is
arge compared with the face. The posterior
facet is convex, and remarkably extended up-
wards and laterally, and is continued insensibly
at an obtuse angle with the upper surface.
The occipital foramen is almost horizontal.
The temporal fossez are not very deep, and do
not meet above at the middle line. The cere-
bral convexities are not strongly marked ; the
frontal region is flat. A longitudinal furrow
extends arenes the whole upper surface of the
cranium, and is especially remarkable in the
Owls. The cranium and face are separated by
a sudden contraction. The orbits are very
complete, on account of the development and
complete junction of the frontal, ethmoidal,
ungueal, and palatine boundaries.

The cranium of the Warblers presents a
more regular sphericity, but the interorbital
space is very concave. The anterior parietes
of the orbits are large and very complete from
the size of the lachrymal bone and of the trans-
verse lamina of the ethmoid; the internal and
posterior bony parietes are, on the other hand,
remarkably defective; the optic foramina are
indeed commonly blended into one, and con-
tinuous with the larger fissures above.

The distinctive characters of the skull of the
Scansores are the most remarkable, especially
in the Parrots and Toucans. In the former
the upper surface of the cranium is flattened or
slightly convex, and greatly extended in breadth
between the orbits. These cavities are very
complete ; and the nasal inlets on the sides of
the skull are much limited in size by the extent
However, the breadth of the
posterior part of the base of the cranium and
the large size of the pterygoid bones occasion
a very considerable interval between these and
the body of the sphenoid.

In the Toucans the cranium slightly in-
creases in breadth to the anterior part where it
is joined to the enormous bill. Its superior
surface presents au equable convexity. The
temporal fosse, like those of the parrots, are
small, and wholly confined to the lateral
aspects of the cranium. The posterior sur-
face, which is absolutely concave in the Mac-
caws, from the backward extension of the
mastoid processes, is slightly convex in the
Toucans, where it is separated from the upper
surface by a regularly arched ridge. The
cerebellic prominence extends over the occi-
oka foramen, the plane of which inclines
orwards and downwards from the horizontal
line at an angle of 45°. The circumference
of the orbit is uninclosed by bone at the pos-
terior part, the postorbital processes of the
frontal not being developed as in the parrots.
The zygomatic process of the temporal, with

the ligament extending between it and the
malar bone, forms here the posterior boundary
of the orbit. The septum of the orbits is very
incomplete. The ungueo-maxillary fissure and
the external nasal apertures are very small,
and situated on nearly the same perpendicular
line, the nostrils open on the posterior part
of the upper mandible, and the remainder of
the lateral facet is, therefore, a smooth entire
osseous surface formed by the thin parietes of
the dilated cellular mandibles.

In the Hornbills the skull presents the same
characters as in the Toucans, with the exception
of that extraordinary species the Helmeted
Hornbill ( Buceros Galeatus..) In this bird the
whole outer surface of the skull is sculptured
with irregular furrows and risings, a character
which it presents in no other bird, and which
can only be compared to the surface of the
skull in the Crocodiles. The posterior surface
is concave, and separated by a strongly deve-
loped ridge from the temporal furrows, which
almost meet at the vertex. The bony rim of
the orbit is completed by the extension of the
zygomatic process of the temporal to that of
the malar ie. which, however, are not an-
chylosed, but joined by a ligamentous union.
The bony septum of the orbits is complete, and
formed by two strong plates, separated by an
intermediate cellular diploé, except at the pos-
terior part. The optic foramen is directed
transversely outwards. In all the Hornbills
the malar bone is moveably connected with the
maxillary as well as the tympanic bones, as in
other birds.

In the Wood-peckers the cranium is round-
ed, the temporal fosse shallow, the internal
wall or septum of the orbits incomplete, but
the anterior boundary is well developed. The
posterior facet of the cranium is raised. The
superior surface is traversed by a wide furrow
extending longitudinally forwards, generally to
the right, but sometimes also to the left, as far
as the lachrymal bone. It is in this furrow
that the elongated cornua of the os hyoides are
lodged, which relate to a peculiar mechanism
hereafter to be described. In some of the
larger species of Wood-pecker, as the Picus
major, L. the cranial furrow is more symme-
trical. In the Humming-birds it is double, the
hyoidean furrows being separated at first by the
cerebellic protuberance, and afterwards by a
mesial longitudinal ridge.

The skull in the Rasorial birds is narrow,
but slightly raised, and without ridges. In
the Capercailzie ( Tetrao Urogallus) it is
almost square, flattened on the posterior and
superior surfaces, and impressed with a con-
siderable longitudinal furrow anteriorly. The
orbit is very incomplete, the anterior pa-
rietes being almost entirely wanting, and the
ungueo-maxillary vacancy being consequently
continuous with the orbit. In the Bustards
the posterior boundary of the ungueo-maxillary
fissure is complete, but in other respects the
cranium resembles that of the Rasores.

The skull is remarkable for its length in the
majority of the Waders. In the Herons and
Bitterns the occipital region is low, and inclines

280 AVES.

from below upwards and forwards; it is sepa-
rated. from the upper and lateral regions by a
well developed, sharp, lambdoidal crest; and it
is divided into two lateral moieties by a slight
Jongitudinal ridge. The temporal fosse are
deeper and wider than in any of the preceding
orders; and they now extend upwards, as in
many of the carnivorous mammalia, to the sa-
gittal line, along which an osseous crest is
developed to extend the surface of attachment
of the temporal muscles. The cranium is ex-
panded, anteriorly to the above fossz, as if to
allow of a compensating space for the develop-
ment of the cerebral hemispheres, the interspace
of which is indicated by a deep longitudinal
furrow, almost peculiar to these genera of
birds. The roof of the orbits is expanded late-
rally, which gives great breadth to this part of
the head, but the posterior orbital walls are
very imperfect, and the internal walls or septum
almost wholly wanting. The optic foramina
are blended with each other and with the
smaller foramina, which in other birds represent
the foramen lacerum orbitale. The anterior
boundary of the orbits is also very imperfectly
completed, the ungueo-naso-maxillary and an-
terior nasal fissures aré not remarkable for their
extent.

Woodcocks, Snipes, Curlews, and Lapwings,
resemble Herons in their defective bony orbits;
but they want the extended superior parietes
of those cavities, and differ much in the al-
most spherical form of the cranium, which is
smooth and devoid of the muscular ridges
characteristic of the fish-feeding Gralle. In
this order the intermaxillary bones present
some of their most eccentric forms. They are
narrow, elongated, and curved downwards in
the Ibises and Curlews ; bent upwards in the
contrary direction in the Avosets; extended ina
straight line in the Snipes; singularly widened,
and hollowed out in the Boat-bill ( Cancroma );
widened, flattened, and dilated at the ex-
tremity in the Spoon-bill; thickened, rounded,
and bent downwards at an obtuse angle in the
Flamingo.

Among the Natatores, the sea-birds, as
the Divers, ( Colymbus ), Grebes, ( Podiceps ),
and Cormorants (Carbo), are characterized
for the defective condition of the bony orbits,
and of the anterior parietes of the cranium;
the septum of the orbits is almost entirely
wanting; in place of the posterior parietes
there are two lacune leading directly into the
cranial cavity, one superior, of large size,
and one inferior, smaller; they are, in
general, separated by a narrow. osseous bar,
but in the Coulterneb, ( Fratercula arctica )
this is also wanting, so that all the anterior
cerebral nerves escape by a common open-
ing. But in this species it must be observed,
that the vertical lamina of the ethmoid is
ossified at its posterior part. In the Petrels
and Albatrosses, the internal and_ posterior
walls of the orbits are more complete. In
the Diomedea exulans the optic foramina are
separated both from each other, and from
the neighbouring outlet. The occipital re-
gion is low, and divided into a superior and an

inferior facet, the latter being coricave from side

to side. The plane of the occipital foramen is

almost vertical. The occipital or lambdoidal
crista is well-marked, and the temporal fosse
nearly approximate in the middle line. In
these sea-birds and in the Gulls, the lateral
lacune in the bony parietes of the face are
very considerable.

A most remarkable characteristic of the cra~
nium of both the Brachypterous and Macro-
pterous Sea-birds is the presence of the two
deep, elongated, semilunar glandulardepressions
before mentioned, extending along the roof the
orbits. In thefaquatic birds which frequent the

marshes and fresh waters, as the Anatide or

Lamellirostres, these glandular pits are want-
ing, or very feebly marked, as in the Swans.
They are, however, again met with of large
size, though shallow, in the Curlews ( Nume-
nius) and Avosets ( Recurvirostra); and are
also found, though of smaller size, in the
Flamingo.

Of the thorar.—In every part of the skele-
ton of Birds, we may observe that there is
a close adherence to the oviparous modification
of the vertebrate type of structure. This is
manifested in the forms and connections of the
several vertebrae, and of the cranial bones.
It is no less conspicuous in the structure of
the thorax.

The ribs are apparently in moderate num-
ber, but when their analogues are closely
sought for, they are found to extend, as in
the Crocodile, along the greater part of the
cervical region. In fact the small styliform
processes -which point backwards from the
lateral projections on the anterior parts of the
bodies of these vertebre remain separate after
the true elements of the vertebree have coalesced.
Inan Ostrich which had attained half its growth,
we have found these spurious ribs still moveable.
They anchylose, however, with the transverse
processes in general long before the growth of
the individual is completed, excepting towards
the caudal extremity of the cervical region,
where comparative anatomists, from this cir-
cumstance, have always found a difficulty in
determining the commencement of the dorsal
vertebre. If the moveable ribs had com-
menced, as in Mammalia, by extending to the
sternum, the determination of their number
would have been easy; but they begin, some-
times by a gradual and at others by a sudden
elongation,* opposite the furculum, from which
point, either one, or two, as in the Humming-
bird, (see p, fig. 125,) terminate by extremities
imbedded in muscle, and unconnected with
any corresponding portion extending from the
sternum.

Meckel considers the true number of ribs
in the Diurnal Raptores to be nine pairs,
of the Nocturnal eight; in the Insessores seven
or eight; in the Scansores nine, except the
Cuckoo, which has seven or eight; in the

* This is remarkably the case in the Wood-
Grouse ( Tetrao Urogallus), where the penultimate
and last cervical ribs, instead of gradually enlarg-
ing, diminish in size, so that the determination of
the first thoracic rib is easy. = bg

4

a

AVES.

Rasores seven or eight; in the Struthiones the
number of ribs varies; in the Ostrich (Stru-
thio) we find ten pairs, of which the 3d, 4th,
5th, and 6th, are articulated with the sternum ;
in the Nandou ( Rhea) there are nine pairs,
of which only the 3d, 4th, 5th, and 6th, are
completed by sternal portions; in the Emeu
( Dromaius) there are nine pairs, the 3d, 4th,
5th, 6th, and 7th, being joined to the sternum;
in the Cassowary (Casuarius) there are ten
pairs, and of these the 4th, 5th, 6th, 7th, 8th,
and 9th, have sternal portions. The last pair
of ribs in Struthio and Rhea are extremely
short, and abut against the expanded iliac bones.
Among the Grallatores we find seven pairs of
ribs in the Herons (Ardea), and Gigantic
Stork (Ciconia Argula) while the Cranes
( Grus) have nine, and the Coots and Water-
Hens have ten pairs. In the Natatores, which
vary so much in their locomotive powers and
habits of life, we find a corresponding variety
in the number of ribs; in the Willock ( Uria
troile ) there are twelve pairs, and in the Guil-
lemots and allied sea-birds eleven; in the
Swans eleven; in the Penguins nine, of which
Six are articulated with the sternum.

The true ribs are not joined to the sternum

by elastic cartilages, but by straight osseous

portions, called sternal ribs, (9, fig. 125,
h, fig. 129,) which are moveably connected at
both their extremities. These are the centres
upon which the respiratory motions hinge ; the
angle between the vertebral and sternal ribs,
and between these and the sternum becoming
more open in inspiration, and the contrary
when the sternum is approximated to the dorsal
‘region in expiration.

As the ribs are traced backwards, their
vertebral extremities are seen to become gra-
dually double or bifurcated from the in-
creasing development of the part answering
to the cervix and head of the mb in Mam-
malia. The spurious cervical ribs, may be
plainly seen to be articulated, like the pos-
terior spurious ribs of the Cetacea, by the
tubercle only; and, as they increase in length
in the proximity of the thorax, the head of the
rib is then seen to be thrown downwards to
join a distinct tubercle on the side of the body
of the vertebra close to its anterior margin,
but without encroaching on the intervertebral
space. ‘The comparative immobility of the
dorsal vertebree allows of this mode of articu-
lation; but it is an interesting circumstance
that in the Ostrich, where the costal vertebre
preserve their mobility, the heads of the ribs,
at least of those of the anterior ones, evidently
pass forwards to the intervertebral space. The
tubercle of the rib has thus less the character
of a subordinate process than in the ribs of
mammalia; it is supported on a pedicle, and
is articulated by a was synovial joint with
the transverse process of the corresponding ver-
tebra. The ribs, below the union of the two
articular processes, are thick and strong, but
they gradually become flattened, and increase
in breadth as they descend towards the sternum.
This is especially remarkable in the second,
third, and fourth ribs of the Woodpecker.

281

The dorsal ribs are not only connected together
by muscles and aponeurotic membranes, but
cooperate with the anchylosed dorsal vertebra,
in giving stability to the trunk by means of
small osseous splints, detached from the pos-
terior margin of each true mb, and directed
backwards and upwards to the next in suc-
cession, to both of which they are united by
means of oblique fibrous ligaments. .In birds
of powerful flight these connecting pieces are,
as might be expected, most developed. In
the Raptores they extend beyond and overlap
the succeeding posterior rib, and in this order
they are anchylosed.

In some of the Struthious birds, as the
Ostrich and Rhea, they exist from the third to
the fifth rib, while in the Emeu and Cassowary
there are only rudimentary traces of them.
In the Penguins these accessory processes are
remarkable for their breadth, but they are
never anchylosed to the ribs, and consequently
are apt to be lost if care be not taken in pre-
paring the skeleton.

The sternal ribs (h, h, fig. 129) are of a less
flattened form than the vertebral ; they increase
in length as they are situated further back ;
their costal extremity is simply rounded, while
their sternal extremity is extended transversely
and divided into two smooth surfaces moveably
articulated by two synovial capsules with cor-
responding cavities in the sides of the sternum.
The first sternal rib is, however, joined by
fibro-cartilaginous substance only, while one
or two of the posterior pieces are anchylosed
with the rib immediately preceding them, and
do not reach the sternum. In the Ostrich
the last rib abuts against the ilium, to which it
is anchylosed.

In the Peacock, Pintado, and common Fowl,
the vertebral and sternal portions of the last
pair of ribs are unconnected with each other ;
the latter thus representing the ossified ten-
dinous intersections of the rectus abdominis
muscle, as in the Crocodile. This analogy is
still more striking in the Herons, Storks, and
Curlews, and in many of the Natatores, in
which the sternal portions alone exist, and are
remarkably elongated.

The part of the skeleton which has undergone
the most remarkable modifications in relation
to the powers and functions of the anterior ex-
tremities is the sternum, (r,s, fig. 125 and 129,)
which gives origin to their principal muscles.
It is so developed, both in length and breadth,
as to extend over the whole of the anterior or
ventral aspect of the thoracic and of a great
part of the abdominal cavities, reaching in
some birds of great powers of flight even to
the pubic bones, so as to require removal be-
fore the abdominal cavity can be examined.

In order to afford origin to the accumulated
fasciculi of the pectoral muscles, which other-
wise would become blended together over
the middle of the sternum, an osseous crest
(s, fig. 125, a, fig. 130) is, extended down-
wards, analogous to the cranial crest which
intervenes to the temporal muscles in the
carnivorous mammalia; and as this crest in-
dicates in these the powers of the jaw, so the

282 AVES.

sternal keel bespeaks the strength of the ante-
rior extremity in the bird.

Besides the difference of form and deve-
lopment of the mesial crest or keel, the ex-
tended sternum presents many other varieties
in the different orders and families of birds.
A zoological arrangement of the class has even
been founded on the modifications of this cha-
racteristic and important part of the skeleton.
In every species the sternum is more or less

Fig. 129.

7
‘

i
‘

‘
/

Sternum, coracoids, and clavicles of a Woodpecker.

quadrilateral, more or less convex outwardly,
and each of its margins affords distinctive
characters. The anterior margin presents two
grooves (b, b, figs. 129, 130) extending along
the greater part of either side, and affording a
secure articulation to the coracoid bones; and
in many birds it sends forward a process from
the middle part where the two grooves meet,
as in the Woodpecker and Penguin (e, fig.
129). This mesial process we shall term the
manubrial process, since it is analogous to that
which extends from the manubrium or first
sternal bone of the seal, mole, &c.

The lateral margins are straight and excavated
anteriorly, to a greater or less extent, for the
lodgement of the sternal ribs. In some birds
a process (d, figs. 129, 130) is given off at
each angle of the union of the lateral with the
anterior margin: as this process seems to
supply the sternal portions of the anterior
floating ribs, it may be termed the costal
process.

The posterior margin is most varied in its
contour, and is in general interrupted by fis-
sures, (f, f, figs. 129, 130.) which are always
symmetrical in their position, but vary in
number and depth, so that this margin is some-
times represented by the extremities of three
or five long processes.

In the Diurnal Raptores the sternum is a
large elongated parallelogram, convex both in

the direction of its length and breadth, but
especially in the latter sense. The manubrial
process is thick, the contour of the keel
convex, and its margin extended laterally.

In the Eagles and Secretary-bird the ster-
num is entire, but in the Vultures and Hawks
it is pierced on either side by a small round
aperture situated near the posterior margin.
Ossification sometimes extends along the apo-
neurotic membrane stretched over this aperture
so as to divide it into two, as has been ob-
served in the Buzzard; or so as to obliterate it on
one side only, as seen by Meckel in the Kite.

In the Nocturnal Raptores the sternum is
short, convex as in the preceding tribe, but
weaker: there isno manubrial process. The
keel is less developed, its margin less convex,
and not thickened. The posterior margin is
concave and presents two fissures, separated
by a middle process, except in the common
Barn Owl (Strix flammea _) where it is wanting,
and a large but shallow fissure is found in-
stead.

The greater part of the Insessorial Birds are
characterized by the following form of sternum.
It is large, a little longer than broad, and
pinched in, as it were, at the sides, just behind
the costal margin. The keel is prominent and
convex. along its inferior margin ; its anterior
margin is slightly excavated, and terminates
below in a slightly projecting angle. The ma-
nubrial process is compressed, prominent, and
curved upwards ; the costal processes are mo-
derately developed. The posterior margin pre-
sents a single deep fissure on either side, and
a single lateral process, the extremity of which
is constantly dilated. The lateral margins are
slightly excavated.

In the Corvide the keel is more excavated
at its anterior margin; the manubrial process
is stronger, and is bifurcated at the extremity ;
the posterior fissures are shallower ; the angular
processes directed outwardly and not dilated
at the extremity. In the Swallows ( Hirun-
do) the sternum is large and the keel greatly
developed ; there are two posterior fissures,
but they are still shallower than in the Crowst;
the angular processes are not dilated at the
extremities. In the Swifts (Cypselus) the
sternum is entire, and corresponds in its pro-
portional magnitude with the superior length
and power of wing which characterizes this
genus. The manubrial process is wanting, but
the costal processes are moderately long and
pointed.

In the Humming-birds, which sustain them-
selves on the wing during the greater part of
the day, and hover above the plant while ex-
tracting its juices, the sternum (r, s, fig. 125,)
is still further developed as compared with the
body ; it approaches to a triangular form, ex-
panding posteriorly, where the margin is entire,
and rounded. The depth of the keel exceeds
that of the entire breadth of the stenum. The
coracoid depressions are deep and approxi-
mated ; the manubrial process is sm if but
evident, and directed upwards ; the costal pro-
cesses are also present, but of small size.

In the Creepers (Certhia) and Hoopoes

AVES.

(Upupa), the sternum again becomes dimi-
nished in size, and presents the two fissures on
the posterior margin; the keel is moderately
developed ; the manubrial process is produced
anteriorly; it is of a compressed form in the
Hloopoe, but thick, and bifurcate in the
Creepers; there are no costal processes.

In the Wood-peckers the keel of the ster-
num is more feebly developed, its inferior
margin is straight, and the angle formed by its
union with the anterior margin truncate. The
manubrial process enlarges as it advances
forwards, and is bifureate at the extremity.
The costal processes are also long, and curved
forwards; the posterior margin has four deep
notches (ff, fig. 129 ).

In the Trogons, Kollers ( Coracias ), King-
fishers, Bee-eaters ( Merops), Toucans, and
Touracos, the sternum is characterized by two
fissures on either side at the posterior margin.

In the Parrot tribe the sternum again singu-
larly resembles in its integrity that of the higher
Raptores, being in somespecies simply perforated
on either side near the posterior margin, and in
others wholly ossified. It is, however, narrower
in proportion to its breadth. The keel is well
developed, its inferior margin concave, its an-
terior one describing a siginoid flexure ; their
angle of union rounded. The costal depres-
sions occupy almost the entire lateral margins
of the sternum. The manubrial process is
slightly developed, trihedral, and truncate at
the extremity.

In the Pigeons, which unite the In-
sessorial to the Gallinaceous order, the ster-
num is narrow, but the keel is deep, with its
inferior border convex, and the anterior one
curved forwards, thin and trenchant; the ma-
nubrial process is strong and bifurcated; the
costal processes short. The posterior margin
is cleft by two fissures on either side of the
mesial plane, the lateral and superior fissures
being the deepest ; the mesial ones are occasion-
ally converted into a foramen. The costal surface
of the lateral margin is, as in the Gallinaceous
birds, of very little extent. In the Crown
Pigeon the superior fissures are so deep and
wide as to convert the rest of the lateral margin
into a mere flattened process, which is dilated
at the extremity.

In the true Rasores the four posterior fis-
sures of the sternum are so deep and wide
from its defective ossification, as to give to the
- lateral parts of this bone, or hypo-sternal
elements, the appearance of a bifurcated pro-
cess extending backwards from the costal
margin. ‘The mesial fissures are here the
deepest, extending as far as the anterior
border of the keel. This part is short, straight,
or very slightly convex inferiorly ; concave at
the anterior margin, which is formed by two
tidges which converge to it from the anterior
margin of the sternum. This margin is con-
vex laterally, and largely excavated for the
coracoid bones ; the depressions are continuous
with each other, and the compressed manubrial
process, arching over the canal, converts it into
a foramen. The costal processes are prolonged
upwards and forwards; the posterior lateral

283

processes pass backwards exterior to the ribs,
supporting them in the Capercailzie, like a
semi-hoop ; these processes are dilated at their
extremities.

In the Grallatores or Waders the sternum
corresponds in size to the shortness of the
thoracic-abdominal cavity. In the Ardeide
the grooves of the anterior surface pass reci-
procally beyond the middle line, increasing the
surface of attachment for the expanded lower
and posterior extremities of the coracoid bone.
In most of the genera the posterior margin pre-
sents a single fissure on either side; these in
the Storks and Herons are wider at the com-
mencement than at the termination. In the Plo-
vers, Woodcocks, Avosets, and Oyster-catchers,
it occupies the whole breadth of the sternum.
In the Curlews, Ibises, and Spoonbills, there
are two fissures on either side, In the Coots
and Water-hens the single fissures on either
side of the keel are long and narrow, and the
lateral portions of the sternum extend back-
wards beyond the middle, and become larger
towards their extremities.

Among the Natatores, the Albatrosses,
Petrels, Pelicans, and Cormorants present a
strong wide convex sternum, similar to the
Storks and Herons; the keel is moderately
developed, but prolonged anteriorly ; the pos-
terior margin presents a single slight fissure
on either side. In the Penguins, these fissures
are of considerable extent (f, f, fig. 130,); but
the keel of the sternum is well developed,
even in the Aptenodytes ; its inferior border is
straight. In the Gulls and Sea-swallows the
sternum is of large size, wide, and convex ;
it presents posteriorly two small and shallow
fissures on either side, of which the lateral and
superior are sometimes converted into foramina.
The keel extends along the whole of the ster-
num, but is of moderate depth, and convex
inferiorly.

In the Anatide or Lamellirostral tribe the
sternum is thin, but of large size, very convex
transversely, and much elongated. The keel
is of moderate depth, and of a triangular form,
its inferior margin being straight ; there is only
one fissure on either side posteriorly.*

In the Divers (Colymbus) the portion of
sternum intermediate to the two fissures is pro-
longed beyond the lateral pieces, and the ma-
nubrial process is strongly developed, and of a
rounded form; the whole bone is remarkable
for its length. In the Grebes the sternum is
characterized by a third mesial fissure of a
chevron figure intermediate to the two ordinary
fissures of the posterior margin.

The sternum of the Cursorial Birds pre-
sents few aftinities of structure to that of the
rest of the class, resembling rather the ex-
pamhlct plastron or abdominal plate of the

ortoises. It has neither a keel, nor manu-
brial, nor costal processes, and may be com-
pared to a square shield. It is most convex
in the Rhea, and least so in the Ostrich;

* The modifications of the sternum in relation to
the folded trachea will be treated of in the article
on the Organs of Voice.

284

in the latter there may be observed slight indi-
cations of the two ordinary posterior fissures.

_ The ossification of the perfect sternum of
the Bird commences from five centres, —a
middle one which supports the keel, termed by
by Geoffroy St. Hilaire the entosternal (a, fig.
129); two anterior lateral pieces, the hyoster-
nals (b, b, fig. 129), and two posterior lateral
pieces, the hyposternals (cc, fig. 129). The
posterior cartilaginous appendages he terms
viphi-sternals (g g, fig. 129, 130). If to these
be added the two portions or episternals of
which he supposes the manubrial process to
be composed, then nine elements may be
reckoned to enter into the composition of the

Fig.

sternum; but, hitherto, we have only met
with a single ossific centre in the manubrial
process. Where the keel is absent, as in the
Cursores, the entosternal piece appears to be
wanting, and the ossification of the sternum
here radiates from lateral centres only.

Of the anterior extremity—The bones of
the anterior extremity do not present that ex-
traordinary development in the bird that might
be expected from the powers of the member
of which they are the basis. The great expanse
of the wing is here gained at the expense of the
epidermoid system, and not exclusively pro-
duced by folds of the skin requiring elongated
bones to support them, as in the Bats, Dragons,
and Flying-fish. The wing-bones are, however,
both in their forms and modes of articulation,
highly characteristic of the powers and appli-
cation of the muscular apparatus requisite for
their due actions in flight.

The bones of the shoulder consist, on each
side, of a scapula (h, fig. 130), a coracoid
bone (i), and a clavicle (k),—the clavicles
being mostly anchylosed together at their mesial
extremities, constitute a single bone, which, from
its peculiar form, is termed the os furcatorium
or furculum. In the Ostrich the two clavicles
are distinct from each other, but are severally
anchylosed with the coracoid and scapula, so as
to form one bone on either side. In almost
every other species of bird the scapula, coracoid,
and clavicle remain separate or moveably articu-
lated throughout life. In the American Ostrich
(Rhea) and Java Cassowary ( Casuarius )
the acromial element or clavicle is anchylosed
with, or rather is a continuous ossification from,
the scapula; but the coracoid bone is free ;
and this condition is worthy of notice as it
is precisely that which the bones of the shoul-
der present in the Chelonian Reptiles; where

AVES. f
the coracoid element has been err neously re= oa
garded as the clavicle, in consequence of its

being moveably articulated with the scapular
piece. In the Emeu ( Dromaius ) it is interesting
to observe that the clavicle commences by a dis-
tinct ossification, and long continues oe

it does not reach the sternum, but holds the ©

same relative situation as the continuous acro-

mial or clavicular process of the scapula in the ~

other Struthious birds.

The scapula (t, fig. 125, h, fig. 130) is
most readily recognised as such, in the Pen-
guins of the genus Aptenodytes, where it is
broader and flatter than in any other bird: in
these, however, it is of considerable length in

130.

proportion to its breadth, and does not exhibit
any trace of spinous process. In the rest of the
class it is a simple narrow elongated bony
lamina, increasing in thickness as it approaches
the joint of the shoulder; there it is extended
in the transverse direction, forming externally
the posterior half of the glenoid cavity,and being
internally more or less produced to meet the
clavicle, while it is strongly attached in the re-
mainder of its anterior surface to the coracoid
bone. The position of the scapula is longitudi-
nal,being extended backwards from theshoulder,
parallel to the vertebral column, towards which,
however, it, in general, presents a slight convex-

ity. In birds of strong powers of flight, as in the -

Swift, ( Cypselus,) it reaches to the last rib,

while in the Emeu, on the contrary, it extends _

over two ribs only. In the Humming-bird
( Trochilus ) its posterior third is bent down-
wards at a slight angle.

The coracoid (u, fig.125,i, figs. 129, 130), or
posterior clavicle, is always the strongest of
the bones composing the scapular arch: its ex-
panded extremity is securely lodged helow
in the transverse groove at the anterior part of
the sternum, from which it extends upwards,
outwards, and forwards, but frequently al-
most in the vertical position to the shoulder-
joint, where it is united at an acute with
the scapula and clavicle. It thus

.

a —

eT
er

AVES.

main support to the wing, and the great point
of resistance to the humeri during the down-
ward stroke of this aerial oar. ‘The superior or
humeral end of this bone is commonly bifur-
cate ; the outer process is the strongest, and
completes the glenoid cavity anteriorly, (J,
Jig.130,) above which it rises, to a greater or less
extent, and affords, on its inner side, an arti-
cular surface for part of the acromial end of the
clavicle: the inner process is short and com-
pressed, and is also joined by ligament to the
acromial end of the clavicle. Just below the
origins of these processes an articular surface
extends transversely across the posterior part of
the coracoid bone by which it is firmly united
by fibro-cartilaginous substance to the scapula.
The glenoid cavity resulting from the union of
these two bones is not, however, always equal
to the reception of the entire head of the hu-
merus. In the birds, which Mr. Vigors re-
gards as composing the typical orders of the
class, viz. the Raptores and Insessores, (the
aves aeree of Nitzsch,) a small but distinct bone
extends between the scapula and coracoideum
along the superior part of the articular cavity for
the humerus, which it thus completes. Nitzsch,
the discoverer of this element of the scapular
apparatus, denominates it the capsular bone,
( Schulterkapselbeine ) ; by Meckel it is called
the Os humero-scapulare, and is regarded as
the analogue of the scapula inferior of reptiles.
In the Aberrant orders of birds, as the Rasores,
Grallatores, and Natatores, there is, in place
of this bone, a strong elastic ligament or fibro-
cartilage extended between the scapula and
coracoideum, against which that part of the
head of the humerus rests, which is not in con-
tact with the glenoid cavity.

The clavicles (v, fig. 125, 6, fig. 130) in
birfls, as inthe mammalia, are the most variable
elements of the scapular apparatus. In the
Ground Parrots of Australia ( Pezophorus, Il-
liger) they are rudimentary or wholly deficient ;*
they are represented by short processes in the
Emeu, Rhea,and Cassowary; they do not come
in contact inferiorly in the Ostrich, although
they reach the sternum. In the Toucans they are
separate, and do not reach the sternum. In the
Hornbills and Screech Owl (Strix ulula) they
are united at their inferior extremities by carti-
lage. In the rest of the class they are anchylosed
together inferiorly, and so constitute one bone,
the furculum, or merrythought. From the point
of union a compressed process extends down-
wards in the Diurnal Raptores, the Coniros-
iral Insessores, the Rasores, most of the Gral-
latores, and Natatores, in which a ligament
extends from its extremity to the ento-sternum.
The process itself reaches the sternum, and is an-
chylosed therewith in the Pelicans, Cormorants,
Grebes, Petrels, and Tropic-bird; also in the
Gigantic Crane, and Storks in general. In
the Humming-birds, where the sternum is so
disproportionately developed, the furculum ter-
minates almost opposite the commencement of
the keel, but at some distance before it; in

* Mr. Vigors has noticed the absence of the os
furcatorium in Psittacus mitratus, Platycercus eximius,
and Psittacula Galgula,

285

those species in which we have examined it, be-
longing to the genus Trochilus, Lacep. it is of
equal length with the coracoideum, and not
shorter, as Meckel asserts. As the principal
use of this elastic bony arch is to oppose the
forces which tend to press the humeri inwards
towards the mesial plane, during the downward
stroke of the wing, and restore them to their
former position, the clavicles composing it are
stronger, and the angle of their univun is
more open, as the powers of flight are enjoyed
in greater perfection; of this adjustment the
Swifts, Goat-suckers, and Diurnal Birds of
Prey afford the best examples.

Notwithstanding the anterior extremity is
limited to one function, and the motions of its
parts are confined to simple folding and exten-
sion, it contains the same number of joints as
the arm of the Monkey, or of Man himself. We
shall now successively consider the bones of the
Brachium, Antibrachium, Carpus, Metacarpus,
and Digits.

The brachium, or humerus (w, fig. 125,
m, fig. 130) is principally characterized by
the forms of its extremities. The head, or
proximal extremity, is transversely oblong to
play in the articular cavity formed by the union
of the scapula and coracoid bone. It is further
enlarged by two lateral crests: of these the
superior, or external, which is angular, with the
thin margin turned forward, affords an adequate
attachment to the great pectoral muscle: the
opposite process has its margin rounded and
curved backwards, and it is beneath the arch
thus formed that the orifices are situated, by
which the air penetrates to the cavity of the
bone. There is always a deep depression at
this part, even in birds which have no air in
the humerus, as in the Penguins and Ostrich.
The distal end of the humerus is not less cha-
racteristic of the bird, and different from that
of other vertebrate animals. The articular hinge
is divided into two parts, one internal, which is
the largest, for the ulna, of an almost spherical
form, and one external, for the radius, of an
elongated figure, extending for some distance
along the anterior surface of the humerus.
The radius is thus made to describe in the act
of bending a greater portion~of a circle than
the ulna, and the whole fore-arm moves ina
plane which is not perpendicular to the anterior
surface of the humerus.

The humerus is not always developed in
length in proportion to the powers of flight;
for although it is shortest in the Struthious
Birds and Penguins, it is also very short in the
Swiftsand Humming-birds. In the latter, how-
ever, it is characterized by its thickness and
strength, the size of its muscular processes,
and the consequent transverse extension of its
extremities; while in the Cursores it is as
attenuated as it is short, and in the Penguins
is reduced to a mere lamina of bone resembling
the corresponding part in the paddle of the
turtle. In the Rasores it rarely equals half
the length of the body; in most other birds it
is about two-thirds that length; it attains its
greatest length in the Albatross. In this and
other sea-birds, as the Gulls, Awks, and Petrels,

286 } AVES.

the humerus presents a notable process at the
outer side, near its lower extremity; and in
the Puffin ( Fratercula arctica) an ossiculum
is moveably articulated to this process.
Another ossiculum may here be noticed, al-
though it belongs rather to the udna, being
essentially the separated olecranon of that bone.
This detached sesamoid bone is found attached
(like the patella of the knee-joint) to the capsular
ligament and the tendons of the extensor mus-
cles, in many of the Raptores, and in the Swifts.
In the Penguins it is double (n, n, fig. 130.)
Of the two bones of the antibrachium
(y; fig. 125) the ulnar (0, fig. 130) is always
the strongest, and especially so in the Stru-
thiones: both this and the radius (p, fig. 130)
are in general slender and straight bones,
slightly enlarged at their extremities, placed
not by the side of, but one in front of the other,
and so articulated together, and with the hu-
merus, as to admit of scarcely any degree of
ronation or supination, which, as Meckel
justly remarks, adds to that firmness and resist-
ing power in the anterior member which are
so necessary during the actions of flight. In
the Penguins, the bones of the fore-arm present
the same modifications as the humerus in re-
lation to the corresponding action in the denser
element, or that of swimming: they are flat-
tened, and are articulated with the anterior
edge, and not the extremity of the humerus.
The bones of the hand are extended in
length, but restricted in lateral development.
The carpus consists of two bones only, (4, fig.
130,) so wedged in between the antibrachium
and metacarpus, as to“limit the motions of the
hand to those of abduction and adduction
necessary for the folding up and expansion of
the wing; the hand is thus fixed in a state of

Pelvis and bones of the leg of the Diver, or Loon.—Colymbus glacialis.

pronation ; all power of flexion, extension, or of
rotation, is removed from the wrist-joint, so that
the wing strikes firmly, and with the full force of
the contraction of the depressor muscles, upon
the resisting air.

The metacarpus is principally formed of two

bones, anchylosed together at both extremities
(r,7r, fig. 130); of these, the one which cor-
oe to the radius is always the largest,
and supports the finger which has the greatest
number of phalanges: a third small rudi-
mental bone is in most birds found an-
chylosed to the outer-side of its proximal
extremity, and this supports the single phalanx
of what is usually called the thumb. The
longest or radial finger is generally composed
of two phalanges (s,s, fig. 130) of moderate
length ; to which, in some birds, a third smaller
phalanx is added. The ulnar finger consists of
a single phalanx only (t, fig. 130). These are
strongly bound together by ligaments and in-
tegument, so that the wing loses nothing of its
force, while it preserves in these separated
bones its analogy with the anterior extremities
in the other vertebrated classes. In Zoology
the large feathers that are attached to the ulnar
side of the hand, are termed Primarié or pri-
mary feathers; those which are attached to thé
fore-arm Secundaria, or secundaries, and Tec-
trices, or wing-coverts ; those which lie over
the humerus are called Scapularia, or scapu-
laries; and those which are attached to the
thumb, Spurie@, or bastard feathers. In some
birds the wing is armed with a spur attached
to a phalanx at the radial side of the so-called
thumb, which, as Nitzsch observes, would
therefore seem analogous to the index finger.

The bones of the leg or posterior extremity
(fig. 131,) do not exactly correspond, in their
divisions or principal
groups, to those of the
wing, the segment corre--
sponding to the carpus
being invariably blended
with the one that suc-
ceeds.

The pelvic bones present
a remarkable contrast to
those of the shoulder,
being always anchylosed
on either side into one
piece, but being with
one ‘exception; never
joined in the mesial line,
whilethis is the only place
where the elements of the
scapular apparatus are in
general united by bone.
In the young bird the
os innominatum is seen
to be formed by the usual
three bones, viz. the zliwm,
ischium, and pubis, corre-
sponding respectively to
the scapula, coracoid, and
clavicle, of the anterior
extremity.

The ilium (0, fig. 125,

a, fig. 131.) 18 the only

AVES.

bone of the pelvis which comes in con-
tact with the vertebral column, and it ex-
tends from the posterior dorsal vertebre along
the whole of the sacrum, to which it is early
united by anchylosis. At its posterior extre-
mity it is expanded laterally and becomes
anchylosed with the ischium (c, fig. 131) pos-
terior to the ischiadic notch (e, fig.131) which
is thus converted into a foramen.

The ilium is of a considerable size, of an
elongated form, expanded at its extremities and
contracted in the middle; the anterior expan-
sion is concave externally, the posterior on the
contrary convex. Besides being anchylosed
with the ischium and sacrum, the spinous and
transverse processes of one or two posterior
dorsal vertebrae are commonly joined to it by
bony union. In the Penguins, however, where
the posterior extremities are ill adapted for
supporting the body in progressive motion
on land, the ilium appears at no time to be
anchylosed with any part of the vertebral co-
lamn. :

The os pubis (@, fig. 125, b b, fig. 131) does
not extend to meet its fellow on the mesial
line, but is commonly directed backwards like
a long bent styliform process (3, fig. 134),
adapted to allow a safe passage to the large
and fragile eggs. In general it unites with the
ischium so as to complete the obturator fora-
men (f, fig. 131), behind which another fo-
ramen is occasionally formed by a second
union with the ischium, as is seen in the Ilum-
ming-bird ; while in other Birds, as the Stork,
it is only united to the ischium at the cotyloid
foramen, and the obturator hole communicates
with a long fissure and is completed posteri-
orly by ligament only. The cotyloid cavity for
the head of the thigh-bone is always incomplete
at its posterior or internal part, which is closed
in the recent state by a strong aponeurosis.

The ischium (c, fig. 131) is a small elon-
gated bone, slightly convex externally, ex-
tending from the acetabulum backwards, pa-
rallel with the ilium.

In the Struthious Birds the pelvis is pro-
portionally very long, but narrow; the ossa
innominata cover the whole of the sacrum,
meeting and joining above that part like the
roof of a dwelling. In the Rhea, or Ame-
rican Ostrich, the ischiadic bones meet below
the sacrum, where they are united for a con-
siderable extent by a symphysis, so that the
sacrum is closely surrounded, and in fact its
place is almost supplied by the ossa inno-
minata, for the development of the included
vertebrae is in consequence so much impeded,
that they can scarcely be detected at this
part; beyond which, however, the coccygeal
vertebra suddenly resume their ordinary mag-
nitude. This union of the ischia does not
take place in the other Struthious birds; but
the Ostrich presents the remarkable exception,
among Birds, of the completion of the pelvic
circle by the anchyloses of the pubic bones at
their inferior extremities.

The femur (6, fig. 125, g, fig. 131) is a short
cylindrical bone, deviating from the straight line

287

by a very slight anterior convexity. The head
is a small hemisphere; joined, without the in-
tervention of a neck, at a right angle, to the
shaft of the bone: it presents at its upper part,
a considerable depression for the attachment of
the round ligament. The single large trochan-
ter generally rises above the articular eminence,
and is continuous with the outer side of the
shaft. The orifice for the admission of air
into the bone is situated anterior to this ca-
vity. The femur is most readily characterised
by the form of its lower extremity: this pre-
sents as usual two condyles, the inner one cor-
responding to the tibia, the outer one, which
is the largest and the longest, resting both upon
the tibia and fibula; upon this condyle a semi-
circular rounded eminence is observed extend-
ing from the front to the back part, and being
lost in a depression at both extremities; the
result of this structure is to put the external
lateral ligament upon the stretch when the
fibula is passing over the middle of the condyle,
and that ligament, being elastic, pulls the
fibula into the cavity in which the ridge termi-
nates, with a jerk—whether the motion be that
of flexion or extension, in either of which con-
ditions the leg is by this structure the more
firmly locked to the thigh. It has been denied
that the spring-joint ever exists at the knee, and
it is probable that all birds do not possess the
requisite structure in the same perfection ; but
@ common indigenous species, the Water-hen,
( Gallinula Chloropus ) affords a good example
of the beautiful mechanism in question. The
femur attains its greatest development in the
Ostrich ; but in this species it is short in com-
parison to the other bones of the leg, the length
of which in the Stilt-bird and other Waders is
attained solely by the elongation of the tibia
and metatarsus.

The tibia (4, fig.125, hh, fig.131) is the prin-
cipal bone of the leg—the fibula (x, fig. 125, #,
fig. 131) appearing as a mere styliform process
tapering to a point below, and anchylosed for a
greater or less extent to the tibia. The tibia is
of a triangular form, especially at its enlarged
superior extremity, the articular surface of which
is unequal, being flat internally, convex at the
centre, and concave externally and in front.
The inferior articular surface of the tibia forms
a considerable transverse trochlea, above which
anteriorly there is a deep depression. In ge-
neral an osseous bridge extends transversely
across this depression, converting it into a
foramen through which the tendon of the Exten-
sor communis digitorum passes.

In the Divers, Grebes, Guillemots, and
Albatrosses the middle and internal crests of the
tibia unite superiorly and are extended up-
wards into a long pointed process (k, fig. 131)
directed inwards and forwards, anterior to, but
not supplying the place of, the patella, (/, fig.
131) which will be always found as a distinct
bone behind this process. The process is most
developed in the genus Colymbus, and affords
extensive attachments by way of insertion to
the extensors of the tibia, and by way of origin
to the extensors of the metatarsus; by means

288

of the latter disposition the power of the back
stroke of the foot is increased.

The Tarsus can only be recognized as a
distinct segment of the leg when the bones
of a very young Bird are examined. But

in the Ostrich, even when it has attained

a third of its natural size, the Astragalus re-
mains ununited to the metatarsus. It is a
flattened transversely oval bone, convex in the
middle of its upper surface, and irregularly
flattened below, where it is adapted to the
three still partially separated bones of the
metatarsus. A rudiment of the os calcis may
be observed in the detached bone which is
found in the tendons of the extensors of the
foot near their insertion. The Capercailzie
( Tetrao urogallus) affords a good example of
this structure. The process (m, fig. 131) in
which the above tendons are inserted, and
which is very prominent in the Rasores, Gral-
latores, and Natatores, must also be regarded
as appertaining to the tarsal series, since it com-
mences by a separate ossification.

In most birds, however, the tendo Achillis
has no sesamoid bone to add to its leverage, and
in all birds the astragalus is soon anchylosed to
the metatarsus, constituting with it one elongated
tarso-metatarsal bone (A, fig.125, n, fig. 131).
Traces of the number of laterally anchylosed
pieces of which the metatarsus is composed
are always more or less indicated by longitu-
dinal grooves. In the Penguins, indeed, the
anchylosis of the three metatarsal bones takes
place at their extremities only, and they are
consequently separated from each other in the
greater part of their extent. They are also
disproportionately short, and bent forwards
upon the tibia, so as to increase the surface of
support required by these birds when standing
in their usually erect position. Inthe Gralla-
tores and Struthiones, on the contrary, the
tarso-metatarsal bone is remarkably elongated,
the extraordinary length of leg in these birds
depending chiefly upon the extent of this seg-
ment of the limb.

In the Stork and congeneric birds, which
sleep on one leg, the ankle-joint presents a
mechanism analogous to that which we have
above described in the knee-joint. Here, how-
ever, the projection which causes the extension
of the elastic ligaments in the motion of the
joint is in the inferior bone. Dr. Macartney
thus describes the mechanism: “ There arises,
from the fore-part of the head of the metatarsal
bone, a round eminence, which passes up be-
tween the projections of the pulley on the an-
terior part of the end of the tibia. This emi-
nence affords a sufficient degree of resistance
to the flexion of the leg to counteract the effect
of the oscillations of the body, and would
prove an insurmountable obstruction to the
motion of the joint, if there were not a socket
within the upper part of the pulley of the
tibia to receive it when the leg is in a bent
position. The lower edge of the socket is
prominent and sharp, and presents a sort of
barrier to the admission of the eminence that
requires a voluntary muscular exertion of the

AVES.

bird to overcome, which being accomplished
it slips in with some force like the end of a
dislocated bone.”* It must be added, that the
elastic lateral ligaments contribute also to jerk
the metatarsal tubercle into the tibial cavities,
and to resist its displacement.

The lower extremity of the metatarsus is
divided into three articular eminences, corres- .
ponding to the ordinary number of anterior
toes. ‘These eminences are convex from before
backwards, and the middle one, which is the
longest, is converted into a pulley by a mesial
groove which traverses it in the same direction. |
The lateral surfaces are simply convex, and
very narrow ; of these the internal is the short-_
est, except in the raptorial birds. At the extre-
mities of the grooves which indicate the lateral
juxtaposition of the metatarsal pieces, there are _
ordinarily foramina extending from before back-
wards through the bone.

A fourth articular surface is observable in
most birds on the inner and posterior side of
the metatarsal bone; this is situated on an ac-
cessory piece which always commences by a
separate ossification, although in some birds it
afterwards becomes anchylosed with the inner-
most of the other juxtaposed components of
the metatarsus. When this does not take place,
the metatarsus presents a rough, more or less
irregular, oval surface, for the firm ligamentous
attachment of the accessory bone which sup- .
ports the back toe, usually termed the hallux or
posterior thumb. This articulating surface is
important as affording a good distinctive cha-
racter for identifying the bones of birds ina
fossil state, and the more so as its position is
indicative of the powers of grasping or perching
—being placed low down, on a level with the
anterior toes, in those birds which enjoy the
insessorial power in the greatest perfection, and _
being gradually removed higher and higher in
the Waders, until it is at length wholly lost, as
in the genus Cursorius, the Bustards, and the
Struthious family. In the Petrel, however,
this accessory metatarsal bone is wanting, al-
though the hallux is present, the two bones of
which are therefore united to the principal me-
tatarsal bone by long ligaments. The tarso-
metatarsal bone is further characterized by
sharp longitudinal ridges of bone on the pos-
terior surface, which afford attachment to the
aponeurotic thece confining the tendons which
glide along the metatarsus to the toes.

In birds, as in mammalia, the number of
toes is subject to great variety; if the spur of
the Gallinaceous tribe be regarded as one, we
may then reckon the ordinary number of five
in these birds, while in the Ostrich the toes are
reduced to two. Birds are, however, the only
class of animals in which the toes, whatever be
their number or relative size, always differ in
the number of their phalanges, yet at the same
time preserve a constancy in that variation.

The following is a tabular view of the nume-
rical relation in the osseous parts of the feet of

* See Transactions of the Royal Irish Academy,
vol. xiii. p. 20, pe

AVES.

birds according to the researches of Cuvier,
the discoverer of this remarkable peculiarity in
the anatomy of birds.

Table of the number of toe phalanges in
Birds.
Number of Phalanges in the

Second,
com-

Fifth or
outer-
Fourth.|most,or
little
toe.

First or
inner- | monl
most | calle
toe or the
Calcar. | Hallux.

Third.

1 Cock foe:
lus), Phea-
sants ( Pha-
sianus ), Tur-
keys, Pea-

cocks hla

and Lopho-
OP ba 2 3 4 5

cide, Tetrao-
nid@e,and the
rest of the
class, except, 2t 3t 4§ 5||
3 The Genera,
Rhea, Dro-
maius, Casu-
arius, Otis,
Cursorius,
Charadrius,
Hematopus,
Arenaria,
Falcinelia,
Himant ‘4
alcdiche,
Diomedea . 3 4 5
4 The Ostrich
(Struthio) . 4 5

The above table shows what are the toes
which are deficient in those birds that do not
possess the ordinary number.

The phalanges are expanded at their extre-
mities, especially at the posterior ; the articular
surfaces are concave at this end, but divided
longitudinally by a narrow convex line, to which
a corresponding unequal surface at the anterior

* This is wanting in the Argus Pheasant; the
Pavo bicalearatus, on the contrary, has two spurs
on each metatarsal bone.

t In the single genus Ceyx among the Insessores,
and Hemipodius among the Rasores, this toe is
wanting. In all the rest, with the exception of
the Swifts ( Cypselus ) it is directed backwards.

¢ In the Dentirostral Insessores this toe is united
by one or two phalanges to the fourth.

§$ According to Cuvier this toe and the fifth in
the Swift ( ) have only three phalanges like
the third. In the Goat-suckers ( Caprimulgus ) and
Herons (Ardea) the claw of this toe is provided
with dentations similar to a comb on its inner side.

|| This toe is stated by Cuvier to have only four
phalanges in the Goat-suckers, and we have ascer-
tained the correctness of the exception, and that
it also obtains inthe Rhea. This toe is united
to the fourth toe as far as the penultimate joint
in the Bee-eaters ( Merops), the Motmots ( Prio-
nites), the King-fishers (Alcedo), the ‘Todies
( Todus ), and the Hornbills ( Buceros ), which form
im consequence the family Syndactyli of Cuvier.
In the Scansores this toe is turned backwards,
and assists the Hallux in opposing the other toes.
The Owls have the power of turning back the
outer toe at pleasure.

VOL. I.

289

end of the preceding phalanx is adapted, con-
stituting a ginglymoid articulation. The ulti-
mate or ungueal phalanges are characterised by
their anterior pointed terminations, which cor-
respond in form, in some degree, to the nature
of the claw.

Foot of the Goat-sucker.

Of the fossil bones of birds.—Birds differ
from each other in a much less degree than qua-
drupeds, less, perhaps, than any other class.
The Penguin and the Ostrich have, indeed,
but a remote external resemblance with the
Eagle or the Swallow, but yet they have never
been regarded as other than birds. The Por-
pesse and the Whale, on the other hand, al-
though their real affinities were pointed out
by Aristotle, have been placed by many sub-
sequent Zoologists in a very different class
from the Lion or the Ape, and in the older
systems of Natural History they always ob-
tained their position among the true fishes.

Osteological characters of the same value
with those which serve to distinguish the
genera, and for the most part the species of
Mammalia, are, therefore, with difficulty found
in the Class of Birds. Cuvier has declared
that the differences in the skeleton of two
species of an ornithological genus are some-
times wholly inappreciable, and that the oste-
ological characters of Genera can rarely be
detected in any other part than in the bones
of the mandibles, which do not always con-
form in a sufficiently characteristic manner
with the modifications of the horny bill.

The determination of the fossil bones of this
class is, therefore, conjectural, or, at least, it
wants much of that demonstrative character
which the bones of quadrupeds afford.

The fossil bones of birds described by Cu-
vier are considered by him to appertain toa
species of Buzzard, Owl, Quail, Woodcock,
Ibis, Sea-lark, and Cormorant; and, although
not remarkable for their number or for their
zoological interest, yet they demonstrate that
the species which existed at that remote period,
when the Anoplotheriums and other extinct
quadrupeds trod the face of the earth, had the
same proportion of parts, the same length of
wings and legs, the same articulations of the
toes, the same form and numerical proportions
of the vertebre; in short, that their whole
organization was regulated by the same general

U

290

laws of co-existence and all that relates to the
nature of the organs and their essential func-
tions, as at the present day. They afford no
evidence, not even a trace of any part having
been lengthened or curtailed, or otherwise pro-
gressively modified, either by the operation of
5 ay causes or by internal voluntary im-
ulse.

. Myology.—The muscular system of Birds
is remarkable for the distinctness and density
of the carneous fibres, their deep red colour,
and their marked separation from the ten-
dons, which are of a brilliant shining colour,
and have a peculiar tendency to ossification.
This high degree of development results from
the rapid circulation of very warm blood,
which is highly oxygenated in consequence of
the activity and extent of the respiratory func-
tion. The energy of the muscular contraction
in this class is in the ratio of the activity of
the vital functions, but its permanent irrita-
bility is proportionally low, as Carus has justly
observed.

Muscles of a Sparrow-hawk.

roperties are mani-
egree in the muscles
of those families of the Insessores which take

These characteristic
fested in the greatest

AVES.

their food on the wing, as the Hirundinide and
Lrochilide (Swallows and Humming-birds) ;
in the Diurnal Raptores and in the long-
winged Palmipedes, as the Albatross, Tropic
Bird, &c. In the more heavy and slow-
moving Herbivorous families, and in the short-
winged Swimmers, as the Penguins, &c. the
muscles resemble those of the Reptilia in their
softness and pale-colour.

The mechanical disposition of the muscular
system is admirably adapted to the aerial loco-
motion of this class; the principal masses
being collected below the centre of gravity,
beneath the sternum, beneath the pelvis, and
upon the thighs, they act like the ballast of a
vessel and assist in maintaining the steadiness
of the body during flight, while at the same
time the extremities require only long and thin
tendons for the communication of the muscu-
lar influence to them and are thereby rendered
light and slender.

Muscles of the trunk.—The muscles of the

_cervical region are the most developed, as might

be expected from the size and mobility of this
part of the spine; the muscles which are situ-
ated on the dorsal and lumbar regions are, on
the other hand, very indistinct, feeble, and but
slightly carneous; they are not, however,
entirely wanting.

The Semi-spinalis dorsi or Opisthotenar, is
easily recognizable, occupying the space be-
tween the spinous and transverse processes,
arising from the anterior margin of the ilium
and the transverse processes of the sacrum,
and attached by means of long tendons to the
transverse processes of the costal vertebra.
It is most developed in those birds which have
the greatest mobility in this part of the spine,
as in the Penguins, in which the external venter
of the muscle is well developed, inserted into
the vertebral ends of the ribs, and adapted to
support the body in the erect position which
these birds assume while standing.

On the mesial aspect of this muscle and
somewhat covered by it, the Spinalis dorsi may
be distinctly traced, passing from the spinous
processes behind, to those at the anterior part
of the trunk and beginning of the neck.

The Cervicalis ascendens (1, fig. 133) is the
chief extensor of the neck: it rises from the
spines of the anterior dorsal vertebre, and is
inserted by long and separate fasciculi into the
posterior articular processes of the second,
third, and fourth cervical vertebre. In this
course it receives descending slips of muscle
from the spines of the inferior cervical vertebra,
and ascending fasciculi, which furnish tendons
to the fifth and sixth vertebra, and to the atlas,
so that it is enabled to extend the neck even
while the head is raised.

Muscles corresponding to the Intertrans-
versales (2) are continued on the neck from
the external belly of the Opisthotenar ; these
slips extend from the articular processes of the
dorsal vertebre to those of the inferior cervical.
Posterior to the Intertransversales, the Semispi-
nalis colli (3) is seen passing from the trans-
verse to the spinous processes. =

The Longus colli arises from the anterior

AVES.

spinous processes of the dorsal vertebra and
from the anterior part of the cervical vertebre,
and these slips diverge to be inserted into the
transverse processes, and their appended styles
or spurious mbs.

A superadded muscle, which may be re-

garded as a continuation of the preceding, and
which corresponds to the increased number of
the vertebrae of the neck, passes from the
transverse processes: of the five superior ver-
tebre to the anterior spines of the vertebre
immediately anterior—a portion of this muscle
is shown at 5.
- No. 6 indicates one of the most remarkable
muscles in the cervical region of Birds; it
is analogous to the Biventer cervicis of mam-
mals, but has a much longer and more
distinct middle tendon, a. 6. Its lower or pos-
terior venter, 5..6, arises by a tendon, most com-
monly from the short spinous processes of the
lowest cervical vertebre, the anterior fleshy
part c is inserted into the squamous spine of
the occiput. This muscle is well developed
in the Ostrich, where it arises as low down as
from the last lumbar vertebra, by a long ten-
don, which is continued to the cervical region
before it joins the fleshy portion, the whole
muscle affording a striking example of the
peculiar development of the tendinous over
the carneous part which characterizes the mus-
cular system of Birds. In the Parrots and
Raptorial birds, however, the carneous exceeds
the tendinous part of this muscle.

The Complexus (7) arises from the articular
and transverse processes of a variable number
of the superior cervical vertebra, and passes
obliquely backwards to be inserted into the
occiput, crossing exteriorly the upper belly of
the preceding muscle.

The Trachelo-mastoideus (8) arises from the
articular processes of the cervical vertebrae from
the second to the sixth, and is inserted into
the posterior part of the basis cranii.

Anterior to the preceding muscle a portion
of the Rectus capitis anticus major may be
seen at 4. This muscle is largely developed,
arising from the anterior part. of the sixth,
seventh, and eighth vertebree, and inserted into
the basis cranii. There are also muscles ana-
logous to the Rectus capitis anticus minor, the
Recti postici majores et minores, the Obliquus
externus or superior, and in the Penguin, a
strong tendon is given off from the Trachelo-
mastoideus which represents the obliquus in-
Jerior of the neck.

When it is remembered that the cervical re-
gion of the spine in Birds is subservient and
essential to all the movements and functions
of the bill, as a prehensile instrument, and a
cleanser of the plumage, we cannot sufficient]
admire the endowments of length, flexibility,
and muscularity, by which it is enabled to
fulfil the important functions of an additional
extremity.

In the caudal region of the spine the fol-
lowing muscles present themselves. On the
dorsal aspect, the Levator coccygis (10) ex-
tends from the transverse processes and lower

291

extremity of the sacrum to the superior spines
of the coccyx and the base of the last or
plough-share vertebra. This muscle may be
regarded as a continuation of the spinalis dorsi.
Beneath it are found strong Interspinales mus-
cles.

The Quadratus coccygis (11) arises from the
transverse processes of the coccygeal vertebre
and is inserted into the shafts of the rectrices
or tail-quills, which it separates and raises.
On the lateral aspect we find the Pubo-coccy-
geus (12) arising from the posterior margin of
the pubis, and inserted also into the shafts of
the exterior rectrices; it is by means of these
muscles in conjunction with the two preceding
that the Peacock spreads its gorgeous tail.

The Ilio-coccygeus (13) extends from the
posterior margin of the ilium to the last coccy-
geal vertebra, and to the small inferior tail-
feathers.

On the ventral or inferior aspect of the tail,
the muscles are in general more feebly developed
than on the opposite side, except in the Wood-
peckers, where the tail, by means of its stiff and
pointed quill-feathers, serves as a prop to sup-
port the bird on the perpendicular trunks of trees
on which it seeks its food. In these the Ischio-
coccygeus (14) is of large size, extending from
the lower edge of the ischiadic tuberosity, and
from the transverse processes of the anterior
coccygeal vertebre to the inferior spines of the
posterior coccygeal vertebrae, and to the sides
of the last compressed or plough-share bone.

The Depressor coccygis (15) extends from
the ventral aspect of the bodies of the anterior
coccygeal vertebre to the inferior spines of the
posterior and to the base of the last vertebra.

Of the Muscles of the head those which are
attached to it for its general motions have
already been described; the remaining mus-
cles of this part are devoted to the movements
of the jaws, the tongue, the eye, and the ear.
The cutaneous muscles of the face are usually
described as being entirely deficient, and the
only ones that can be regarded as belonging
to this series are the slips of panniculus car-
nosus, analogous to an occipito-frontalis (16),
which are chiefly developed in order to elevate
the crest-feathers in those birds which possess
that ornament; there are also cutaneous slips
which belong more properly to the organs of
hearing, and which raise the auricular circle of
feathers in the Owls, Bustards, &c.

The muscles of the jaws are chiefly mo-
dified in relation to the moveable condition
of the upper mandible and tympanic bone,
and the subserviency of the latter to the actions
of these parts.

The Temporalis (17) fills the temporal fossa,
which consequently indicates the bulk of that
muscle in the dry skull. It arises from a
greater or less extent of the temporal and
parietal bones, and, as it passes within the
zygoma, becomes closely blended with the
Masseter ; the united muscles derive an acces-
sion of fibres from the lower part of the
orbit, and are inserted into the raised superior

margin, representing the coronoid process ;
U2

292 AVES. -

and into the sides of the lower jaw from the
articulation as far forward as the commence-
ment of the horny bill.

In the Cormorant there projects backwards
from the spine or squamous element of the
occipital bone, an osseous style about an inch
in length, of a trihedral figure and tapering to
a point. It is not anchylosed as a process of
the occiput, but is moveably articulated to it ;
and its description has been referred to this
section because it does not constitute a regular
part of the skeleton, not representing any
essential element of the bony fabric, but is to
be regarded like the bony tendons of the legs
as an ossification of the intermuscular aponeu-
rosis of the temporal muscles to which it
affords a more extensive and firmer origin,
This, indeed, is its essential use,* for the mus-
cles of the upper part of the neck are inserted
into the occipital bone, and glide beneath the
posterior or superadded fasciculi of the tem-
poral muscle. Analogous parts appended to
the true spinous processes of the vertebra are
met with abundantly in the inferior vertebrate
classes, especially in fishes, where they extend
frequently above the spines of the whole ver-
tebral column, increasing the surface of origin
of the lateral series of muscles.

The muscle analogous to the Biventer
maxille (18) arises by two portions, the one
from the lateral depression of the occiput, the
other from the depression behind and below
the external meatus auditorius; they are in-
serted into the back part and angle of
the lower jaw. A similar disposition of
the digastricus is met with in many of the
mammalia; even in the Orang-utan (Simia
Satyrus) it is equally devoid of a central
tendon, and is unconnected with the os hyoides.

The openers and closers of the mandibles
present very slight differences of bulk in rela-
tion to the development of the parts they are
destined to move; their disproportion to the
bill is, on the contrary, truly remarkable in the
Horn-bills, Toucans, and Pelican, and the bill
is but weakly closed in these in comparison
with the shorter-billed birds.

The upper mandible is moved by three
muscles on either side. The first is ofa radiated
form, arises from the septum of the orbits, and
converges to be inserted into the external and
posterior end of the pterygoid bone, just where
this is articulated to the tympanic bone. It
draws forward the pterygoid bone, which pushes
against and raises the upper jaw.

The second muscle analogous to the External
Pierygoid arises from the space between the
posterior part of the orbit and external meatus
auditorius, and is inserted into the internal
process and contiguous surface of the tympanic
bone; it affects the pterygoid process, and con-
sequently the upper mandible in the same
way as the preceding muscles, and assists in
opening the bill.

The Pterygoideus Internus is a long and

* See Yarrell < On the Anatomy of the Cormo-
ant,’ Zool. Trans, v. iv, p. 235,

slender muscle; it arises from the pterygoid
process and body of the sphenoid, and is in-
serted principally into the inner side of the
lower jaw and tympanic bone; it also sends
off a small tendon to the membrane of the
palate. This muscle draws forward the lower
jaw and depresses the upper one.

In the Cross-bill ( Lovia curvirostra) there |

is a remarkable want of symmetry in the
muscles of the jaws on the two sides of the
head corresponding to their peculiar position.
Those of the side towards which the lower
jaw is drawn in a state of rest (which varies
in different individuals) are most developed,
and act upon the mandibles with a force that
enables the bird to dislodge the seeds of the
fir-cones, which constitute its food.

The articulation of the lower jaw is strength-
ened and its movements restrained by two
strong ligaments, one of these (a) is extended
from the ligament completing the lower part
of the orbit, or from the zygomatic process of
the temporal bone, and is inserted at the outer
protuberance near the joint of the lower jaw,
and must prevent the bill from being too
widely opened. ‘The second ligament extends
from the zygomatic process of the temporal bone
directly backwards to the posterior part of the
articular depression of the lower jaw, and is
designed to guard against the backward dislo-
cation of the lower jaw.

The museles of the ribs.—The levatores
costurum arise from the posterior part of the
extremities of the transverse processes, and
converge to be inserted into the anterior
margin of the succeeding posterior rib. Those
of the first and second ribs represent the
Scaleni, and are of larger size, arising from
the last and penultimate cervical vertebree.

The Intercostales externi appear to be con-
tinuations of the Levatores costarum, and are
usually divided into an anterior and posterior
moiety corresponding to the marked separation
and moveable articulation between the vertebral
and sternal portions of the ribs ; the anterior
division arises from the costal appendage and
extends to the anterior extremity of the rib ;
to afford a more advantageous origin to this
inspiratory muscle would appear, therefore, to
be one of the uses of the costal appendages,
as well as to strengthen the connection of the
ribs to each other.

The Internal intercostals commence at the
sternal extremities of the ribs, as in mammalia,
but extend backwards no farther than the costal

appendages; their fibres run in an opposite

direction to the external intercostals, and are
shorter, the insertion into the posterior suc-
ceeding rib being by a thin but wide aponeu-

rosis: in the Penguin they are, however,

wholly muscular. Two other layers of inter-
costal muscles, corresponding to the triangu-
laris sterni, and having the same direction
of fibres, are extended from before backwards
and outwards to the four anterior sternal por-
tions of the ribs; arising from the superior and
external angle of the sternum. _ .

The muscles of the abdomen are small and

‘
i

AVES.

Weak, in consequence of the protection which the
extended sternum affords to the viscera of that
cavity.

The External oblique (19) is chiefly remarka-
ble for the transverse arrangement of its fibres ;
these arise anteriorly by short fleshy digitations
from the inferior ribs, and by a large but very
thin tendon from the posterior ribs and the edge
of the ilium and pubis; they are inserted by
aponeurosis into the anterior margin of the pubis,
and join the aponeurosis of the opposite
muscle in front of the thin and tendinous
rectus abdominis. This muscle, by drawing
downwards and backwards the posterior part
of the sternum and sternal ribs, opens the
angle between these and the vertebral ribs,
depresses, in consequence, the anterior part
of the sternum, and thus dilates the thorax,
and becomes a muscle of inspiration.

The Internal oblique comes off fleshy from
the anterior moiety of the edge of the pubis,
and tendinous from the posterior moiety of the
same bone; it is much smaller than the pre-
ceding, and is directed forwards and inwards
to the last rib, which it draws backwards, and
thus assists the preceding in the compression
of the abdomen and abdominal air-cells, and
in the dilatation of the thorax.

The Transversalis is a muscle of greater
extent; it arises from the whole anterior margin
of the pubic bones by carneous fibres, and by
digitations from the three posterior ribs; its
tendon unites with that of its fellow in the
mesial line, extends immediately over the pe-
ritoneum over the whole abdomen as far as
the posterior margin of the sternum to which
it is attached.

The Rectus abdominis is not intersected by
tendinous digitations ; its origin is by a broad
thin tendon from the lower and posterior half
of the pubis; at about the middle third
of the abdomen it becomes carneous, and
is inserted into the posterior margin of the
sternum. A mesial tendon or linea alba sepa-
rates the fleshy portions of the two muscles.

The Diaphragm arises by fleshy digitations
from the sternal ribs; in the Ostrich these
digitations are five in number on either side :
the carneous fasciculi do not, however, extend
so far upon the central aponeurosis as even
to be united laterally to one another, and
consequently this muscle has frequently been
denied to birds. From the lungs being con-
fined to the back part of the thorax, the dia-
phragmatic aponeurosis attached to their inferior
surface is not extended as a transverse sep-
tum between the chest and abdomen, but allows
the heart to encroach upon the interspace of
the lobes of the liver, as in reptiles. The
contraction of the muscle tends directly to dilate
the lungs, but is less perfect as an inspiratory
action from the aponeurosis or central tendon
being perforated by large cribriform apertures
for the passage of the air into the abdominal
air-cells,

The Wing-Muscles—The muscles of the
anterior extremity, especially those inserted into
the humerus, are prodigiously developed, and

293

form the most characteristic muscles of the
bird. The muscles of the shoulder, however,
are but small, and those of the distal segments
of the wing still more feeble.

The Trapezius (20), the lower half of which
seems only to be present in birds, arises from
the spines of the lower cervical, and a varying
number of the contiguous dorsal vertebra, and
is inserted into the dorsal margin of the sca-
pula and the corresponding extremity of the
clavicle ; the clavicular portion can commonly
be separated from the scapular.

The Rhomboideus lies immediately beneath
the preceding, and is always single; it passes
in a direction contrary to the trapezius from the
spines of the anterior dorsal vertebra to the
dorsal edge of the scapula.

The Levator scapule arises by digitations
from the transverse process of the last cervical
vertebra, and from the first two ribs; it is inserted
into the posterior part of the dorsal edge of the
scapula, which it raises and pulls forwards.

The Serratus magnus anticus (21) is most
developed in birds of prey; it arises by large
digitations from three or four of the middle
ribs, and converges to be inserted into the ex-
tremity of the scapula.

The Serratus parvus anticus or Pectoralis
minor, as it is termed in Man, arises by digita-
tions from the first and second ribs, and is in-
serted into the commencement of the inferior
margin of the scapula. This is the largest of
the muscles of the scapula in the Penguins.

A muscle, which may be regarded either as
a portion of the Pectoralis minor or as the ana-
logue of the Subclavius muscle, arises from the
anterior angle of the sternum, and is inserted
into the external margin of the sternal extremity
of the coracoid bone.

The Supra-spinatus (22) arises from the ante-
rior part of the outer surface of the scapula, and
is inserted behind the largely developed inter-
nal tuberosity of the humerus.

The muscle which seems to represent both
the Infra-spinatus and Teres major (23) has a
more extensive origin from the outer margin of
the scapula to its extremity, and is inserted
into the internal tuberosity of the humerus.

The Subscapularis arises from the anterior
part of the inner surface of the scapula, and is
inserted into the humeral tuberosity. It is
divided into two portions by the Pectoralis
minor.

The Latissimus dorsi (24, 24,) is but a feeble
muscle in this class, and is constantly divided
into two very distinct slips. The anterior por-
tion arises, more superficial than the trapezius,
from the spines of the four or five anterior
dorsal vertebré, and is inserted near the tendon
of the deltoid into the outer side of the humerus.
The posterior slip comes from the spines of the
dorsal vertebrae above the origin of the gluteus
magnus, and sometimes from the anterior mar-
gin of the same muscle, and is inserted by a
broad and thin tendon immediately in front of
the preceding portion.

The Deltoides (26) is comparatively a small
muscle; it arises from the anterior part of the

294

scapula, and is inserted along the middle of the
- outer side of the humerus; it brings the wing
upward and backward.

Birds have the Pectoralis muscle divided, as
in many of the mammalia, into three portions,
which are so distinct as to be regarded as sepa-
rate muscles ; they all arise from the enormous
sternum, and act upon the proximal extremity
of the humerus.

The first or great Pectoral muscle (25) is ex-
traordinarily developed, and is in general the
largest muscle of the body. In birds of flight it
often equals in weight all the other muscles
of the body put together. It arises from the
anterior part of the outer surface of the clavicle
or furculum, from the keel of the sternum and
from the posterior and external part. of the
lower surface of that bone ; it is inserted by an
extended fleshy margin into the inner side of
the anterior crest of the humerus. It forcibly
depresses the humerus, and consequently forms
the principal instrument in flight.

This muscle is very longand widein the Nata-
tores generally, but in many of these birds, as
the Penguin, its origin is limited to the external
margin of the subjacent pectoral muscle, which
is here remarkably developed. The great pec-
toral is very long, but not very thick in the
Rasores. In the Herons it is shorter, but
much stronger and thicker. Its size is most
remarkable in the Humming-birds, Swallows,
and diurnal Birds of Prey, where it is attached
to almost the whole outer surface of the sternum
and its crest, and has an extended insertion into
the humerus.

In the Ostrich its origin is limited to the an-
terior and external eighth part of the sternum,
and it is inserted by a feeble tendon into the
commencement of the crest of the humerus, to
which it gives a strong rotatory motion for-
wards.

The second Pectoral muscle is situated be-
neath the preceding; it has the form of an
elongated triangle: it arises from the base of
the crest of the sternum and from the mesial
part of the inferior surface of that bone; it in-
creases in size as it ascends, then again be-
comes suddenly contracted, passes upwards
and backwards round the coracoideum, between
that bone and the clavicle, then turns down-
wards and outwards, and is inserted, fleshy,
above and in front of the great pectoral, into
the upper extremity of the humeral crest.

The interspace between the clavicle, cora-
coid, and scapula, through which its tendon
passes, serves as a pulley, by means of which
the direction of the force of the carneous fibres
is changed, and although these fibres ascend
from below towards their insertion, yet they
forcibly raise the humerus, and thus a levator
of the wing is placed without inconvenience
on the lower part of the trunk, and the centre
of gravity proportionally depressed.

In the Penguins, Guillemots, and Gulls,
this muscle is almost the largest of the three,
occupying the whole length of the sternum.
It is remarkable for the length and strength
of its tendon, which is inserted so as to draw

AVES.

forwards the humerus with great force. It is
proportionally the smallest in the Raptores;
and is very small and slender in the Struthious
birds.

We have already alluded to the use which
the Penguin makes of its diminutive anterior
extremities as -water-wings, or fins; to raise

these after. making the down-stroke obvi-

ously requires a greater effort in water than a
bird of flight makes in raising its wings in air:
hence the necessity for a stronger development
of the second pectoral muscle in this and other
Diving Birds, in all of which the wings are
the chief organs of locomotion, in that action,
and consequently require as powerful a deve-
lopment of the pectoral muscles as the gene-
rality of Birds of Flight.

The third Pectoral muscle, which is in ge-
neral the smallest of the three, arises from the
anterior part of the inferior surface of the ster-
num, and also by a more extended origin, from
the posterior moiety of the inferior surface of
the coracoid; it is directed forwards, and is
inserted by a short and strong tendon into the
internal tuberosity of the humerus, which it
depresses.

It is proportionally large in the Penguins
and Gulls, but attains its greatest development
in the Gallinaceous order.

Above the preceding muscle there is another
longer and more slender one, analogous to the
Coraco-brachialis, which arises from the middle
of the posterior surface of the coracoid; its
direction upwards is less vertical than that of
the third pectoral, along the outer side of
which it is attached to the anterior tuberosity
of the humerus. This muscle is wanting in
the Struthionide, is of small size in the
Heron and Goose, is much more developed
in the Raptores and many Natatores, espe-
cially the Penguins, and attains its greatest
relative size in the Rasores, where it arises
from almost the whole of the coracoideum.

Birds in general possess two flexors and one
extensor (27) of the fore-arm, analogous to those
which are found in the mammalia. They have
also the muscles corresponding to the pronators
and supinators of this higher class, but their
action is limited in the feathered tribes to in-

flexion and extension of the fore-arm, and to

adduction and abduction of the hand.

A remarkable muscle, partly analogous in its
origin to the clavicular portion of the deltoid,
but differently inserted, is called by Carus
Extensor plice alaris (30, a b) and forms
one of the most powerful flexors of the
cubit. It is divided into two portions, of
which the anterior and shorter arises from
the internal tuberosity of the humerus; the
posterior and longer from the clavicular ex-
tremity of the coracoid bone. In the Ostrich
and Rhea, however, both portions arise from
the coracoid. The posterior muscle (6) sends
down a long and thin tendon which runs pa-
rallel with the humerus, and is inserted, gene-
rally by a bifurcate extremity, into both the
radius and-ulna. The anterior muscle («)
terminates in a small tendon, which runs

— le

AVES.

along the edge of the aponeurotic expansion
of the wing. In this situation it acquires
exactly the structure and elasticity of the liga-
mentum subflavum or ligamentum nuche ; it
then resumes its ordinary tendinous structure,
passes over the end of the radius, and is in-
serted into the style of the metacarpal bone.
It combines with the preceding muscle in
bending the fore-arm; and further, in conse-
quence of the elasticity of its tendon, puckers
up the soft of the fold of the wing. (See
48, fig. 133.) An analogous structure is met
with in the wing of the bat.

A lesser flexor of the fore-arm, and stretcher
of the alar membrane (31) arises, as a portion
of the serratus magnus from the ribs, and ter-
minates in an aponeurosis inserted into the alar
membrane and fascia of the fore-arm; it is re-
presented in the figure as turned aside.

The Extensor metacarpi radialis longus (32)
is the first muscle which detaches itself from
the external condyle of the humerus (e), and it
forms the radial border of the muscular mass of
the fore-arm ; it terminates in a large tendon
about the middle of the fore-arm, and this
tendon passes along a groove of the radius, over
the carpus, to the phalanx of the so called
thumb, or spurious wing, into the radial margin
of which it is inserted. It raises the hand,
draws it forwards towards the radial margin of
the fore-arm, and retains it in the same plane.
Inthe Penguin this muscle is extremely feeble,
and the tendon is lost in that of the tensor plice
alaris.

The Extensor metacarpi radialis brevis (33)
arises below the preceding from the ulnar edge
of the radius, and is inserted into the phalanx
of the thumb immediately beyond the tendon
of the preceding muscle. The two tendons are
te istinct from one another in the Birds of

rey, the Ostrich and Parrots, but unite at
the lower end of the fore-arm in the Anatide,
Phasianide, and Gruide.

The muscle analogous to the Extensor carpi
ulnaris (34) comes off from the inferior extre-
mity of the outer condyle of the humerus,
passes along the middle of the exterior surface
of the fore-arm, and its tendon, after passing
through a pulley at the distal end of the ulna,
is inserted into the ulnar phalanx. It draws
the hand towards the ulnar edge of the fore-
arm, and is the principal abductor or folder of
the pinion. _

e Flexor metacarpi radialis (35) is a short
and weak muscle, which arises from the inferior
part of the ulna, descends along the internal
side of that bone, winds round its lower extre-
mity and the radial edge of the carpus, passes
beneath the tendon of the radial extensors, and
is inserted, external to the latter, high up into
the dorsal aspect of the radial phalanx of the

metacarpus. In the Ostrich it arises from the
lower third of the ulna. Inthe Penguin it is
wanting.

The Flexor metacarpi ulnaris (36) arises
beneath the fore-arm from the internal pulley
of the ulna, continues fleshy to the pinion, and
is inserted, first into the ulnar carpal bone, then

295

into the ulnar phalanx. The latter insertion is
wanting both in the Ostrich and Penguin.

The muscles of the pinion or hand are few,
and very distinct from one another; the thumb
or spurious wing is moved by four small mus-
cles, viz. two extensors, an abductor, which
draws the thumb forwards, and an adductor.
The second digit receives three short muscles,
two of which are extensors, and the third an
abductor, in this action it is aided by one and
opposed by another of the extensors. The
lesser digit receives an abductor, which comes
from the ulnar edge of the preceding phalanx.

Muscles of the lower extremity.—Notwith-
standing the simplicity of the motions of the
lower or posterior extremity, the muscles of
this part are numerous, and present several
peculiarities in birds. The femur can be moved
freely forward and backward, but its rotation is
limited by a strong ligamentum teres, and the
structure of the hip-joint does not permit it to
be carried under the body, or far outwards.

In consequence of the form of the pelvis,
the psoas magnus and parvus, the obturator
externus and the guadratus lumborum do not
exist in birds.

A large muscle, regarded by Cuvier as the
Obturator internus, takes its origin from the
internal surface of the ischio-pubic bone, it is
directed from behind forwards, and gives off a
strong and long tendon which passes through
the small opening at the anterior part of the
obturator foramen, which is situated between
the pubis and ischium, (f, fig. 131.) In this
situation a muscle, arising from the external
border of the opening, attaches itself to
the preceding, and is inserted conjointly with
it into the posterior and outer aspect of the
trochanter. Meckel compares this muscle with
the pectineus, especially as it exists in the Sau-
rian Reptiles, but observes that as it arises
from both the internal and external surfaces of
the circumference of the obturator foramen, it
may represent both the internal and external
obturator muscles. It is of an extraordinary
size in the Ostrich.

The femur is raised by three muscles.

The most superficial and highest of these
elevators (37) arises bya broad and thin aponeu-
rosis from the anterior and external surface of
the ilium, it is of a square form, descends al-
most in a straight line, and is inserted into the
posterior part of the trochanter. Meckel re-
gards it as analogous to the Gluteus medius:
Carus calls it the Gluteus maximus. But the
latter, according to Meckel, is represented by
the posterior part of what Carus terms the
Rectus femoris latissimus (40).

Anterior to the Gluteus medius of Meckel,
there is a much smaller muscle, which extends
from the anterior margin of the ilium to the
trochanter, where it is inserted in front of the
preceding. It is of an elongated quadrilateral
form, and it represents the Gluteus minor of
quadrupeds. It is wanting in many of the
Natatores, and arrives at its greatest degree of
development in the Raptorial Order.

A third muscle, still smaller and longer than

296

the preceding and situated beneath it, which
arises from the outer margin of the ilium, and
is inserted into that part of the femur which
corresponds to the lesser trochanter, is regarded
by Meckel as the Iliacus internus, which Cu-
vier states to be wanting in Birds. It is, how-
ever, present in most, and is seen highly deve-
loped in the Ostrich.

The muscles analogous to the Pyramidalis
and Gemellus superior exist in Birds.

There are most commonly three adductors of
the thigh. The inferior, external, and posterior
one arises from the middle of the external sur-
face of the anterior margin of the ischio-pubic
bone, and is inserted into the greater part of
the lower half of the femur at 38.

The second and third adductors are situated.

internally to the preceding; the latter of these
may be compared to the Pectineus.

The Sartorius (39) arises from the anterior
point of the ilium, and passes down to be
attached to the head of the tibia; it is an ex-
tensor of the leg upon the thigh.

The Rectus femoris (40) arises by a thin
but wide aponeurosis from the spines of the
sacrum, after a short course it joins the Cruraus
and Vasti (42), and is inserted into the head of
the fibula. It corresponds according to Meckel
with the Tensor vagine femoris and the Gluteus
magnus. .

The Gracilis (41) arises from the superior
part of the pubis, descends along the inner
side of the thigh, and towards the lower extre-
mity of this part, is continued into a long and
strong tendon, which passes in front of the
knee-joint, and over the extensor tendon of the
leg to the outer side of the fibula, whence it pro-
ceeds inwards, anterior to the tendon of the pero-
neal flexor, to become united to the outer origin
of the flexor perforatus of the toes. Meckel con-
siders that the muscle now described represents
the Rectus femoris of mammalia, and regards
as the Gracilis a small and thin muscle, whose
origin has been transferred lower down, from the
pubis to the femur, from the internal side of
which it passes to the internal and superior part
of the tibia. Be this as it may, the disposition
of the former muscle is such, passing, viz. first,
over the convexity of the knee-joint, and after-
wards over the projection of the heel, that from
its connection with a flexor of the toes, these
must necessarily be bent simultaneously with
every inflection of the joints of the knee and
ankle. As these inflections naturally take
place when the lower extremities yield to the
superincumbent weight of the body, birds
are thus enabled to grasp the twigs on which
they rest whilst sleeping, without making any
muscular exertion.

There are three flevors of the leg: one (43)
which, although single, is from its insertion
into the back of the fibula, analogous to the
Biceps flexor cruris of the human subject : ano-
ther on the inside is attached to the tendon of
the extensors of the foot as well as the tibia;
this muscle might be called the Semimembranosus
(44): the third flexor is in the middle (45),
it comes from the ischium, and as it descends

AVES.

it receives a broad fleshy slip from the back of
the femur. It is inserted on the back of the
tibia, the tendon covering those of the extensors
of the heel. :

The muscles of the feet present in Birds
essential resemblances to the same parts in
Reptiles. They are divided into muscles of
the tarsus, of the metatarsus, and of the toes,
the latter being subdivided into long and short.
The principal points in which they differ from
the same muscles in Reptiles and the Mammalia
are the following: their origins and carneous
portions are not situated on the foot but higher
up on the tibia and even on the femur. The
great length of the metatarsus occasions the
smaller muscles to be of a greater proportional
length than in other animals. The muscular
portions are most developed in the Raptores,
Scansores, and Natatores; the Insessores and
Rasores present an intermediate proportion ;
the Cursores and Grallatores have the longest
tendons.

The Gastrocnemius (46) has three distinct
origins: two of these are superficial, one from
the outer, the other from the inner condyle of
the femur; the third origin is lower down from
the inner side of the tibia and fibula (47).
They unite to terminate in a thin and broad
aponeurosis, which after becoming closely con-
nected with a fibro-cartilage appertaining to the
Jlexor digitorum, proceeds to be inserted into
both the outer and inner margins of the tarso-
metatarsal bone.

The Tibialis anticus (48) arises from the an-
terior part of the upper extremity of the tibia,
below which its tendon passes through an
aponeurotic loop extended from the outer to
the inner margin of the tibia. It has also a
second origin, by means of a slender tendon,
from the anterior part of the external condyle
of the femur. It is generally inserted pretty
high up into the tarso-metatarsal bone between
the outer and inner margins; but in the Psié-
tacide it is attached lower down to the internal
border, so as to turn the foot inwards as well as
raise it, a disposition which is extremely favor-
able for the act of climbing.

The Peroneus (49) is amuch smaller muscle ;
it extends from the lower region of the fibula,
and the outer and anterior edge of the tibia to
the tarso-metatarsal bone, into the outer side of
the base of which it is inserted.

The Flexor perforatus seu longus digitorum
(50) forms the superficial and external mus-
cular mass of the leg: it arises by one mass
from the posterior part of the external side of
the femur, immediately in front of the outer
head of the gastrocnemius; another portion
arises from the outside of the lower extremity
of the femur; these two heads unite below the
middle of the leg and constitute one fleshy belly
which gives off three tendons ; these proceed to
the proximal phalanges of the three outer toes
where they bifurcate to give passage to the ten-
dons of the fleror perforans.

The Flexor pollicis (51) arises, by its anterior
head, from the anterior and upper part of the
tibia, and by its posterior head from the ex-

AVES. 297

ternal condyle of the femur; when it has
reached the region of the calcaneum, it passes
backwards through a synovial capsule, and
is inserted into the proximal phalanx of the
thumb, where it is perforated by the tendon
of the perforans muscle.

The Flexor profundus perforans (52) arises
as two distinct muscles, the one from the back
of the femur and the other from the back
of the tibia and fibula; the tendons of these
two portions unite behind the metatarsal bone,
and send off tendons to the last phalanges of
the toes, which perforate those of the flexor
sublimis.

The Extensor longus communis digitorum
arises above from the anterior side of the tibia,
below the tibialis anticus, passes beneath a
strong restraining ligament, then lower down
beneath an osseous bridge, and lastly across
a strong ligament situated at the inferior ex-
tremity of the tarso-metatarsal bone. Below
this part its tendon divides into three slips
which are inserted into the distal phalanges
of the thiee outer toes (53).

There are six long muscles lying on the

metatarsal bone; they are largest and best

marked in those birds which walk most, as
the Aves terrestres. Two of these muscles
are on the posterior surface; one goes to the
base of the external toe, which it abducts ;
the other is inserted into the root of the back
toe, which it bends. The other four muscles are
on the anterior part of the metatarsus : the first
extends the back toe; the second goes to the
base of the first toe, and abducts it; the
third is spread on the root of the middle toe,
which it extends; the fourth lies along the out-
side of the metatarsus, perforates the end of
the bone, and is implanted into the inside of
the external toe, and abducts it.

Progression on land is generally effected in
birds by the alternate advancement of the two
feet; but sometimes they proceed by leaping
or hopping, rather than walking ; both feet are
then firmly fixed on the ground, and the body
is propelled forwards by a sudden extension
of all the joints of the legs. Birds which have
sharp claws, as the Accipitres, §c., retract them
when they hop, to prevent their being blunted.
The Cat tribe, among mammalia, have a me-
chanism effecting a similar purpose. Some
birds derive assistance in terrestrial progression
by the flapping of the wings, and this is
especially the case with the Ostrich, which
runs by the alternate advancement of its legs.

The act of climbing is performed by means
of a peculiar disposition of the toes, aided by
prehension with the beak, as in the Maccaws
and Parrots, or by the prop formed by the stiff
tail-feathers, as in the Mokdposvers.

The act of swimming is rendered eas
to birds by the specific levity of their body,
arising from the extension of the air-cells ;
by the shape of the chest, which resembles
the bottom of a boat; and by the conversion
of the hinder extremities into oars in con-
sequence of the membranes uniting the toes
together. The effect of these web-feet in
water is further assisted by the toes, having their

membranes lying close together when carried
forwards, whilst, on the contrary, they are ex-
panded in striking backwards. The oar-like
action of the hinder legs is still further favoured
by their backward position; and by the meta-
tarsus and toes being placed almost on the same
perpendicular or vertical line with the tibia, an
arrangement, however, which is unfavourable
for walking.

Sailing. —Some birds, as the Swan, partially
expand their wings to the wind while swimming,
and thus move along the waters by means of
sails as well as oars.

The act of diving is performed by the rapid
and forcible action of the wings, beating the
water as in flight, by the feet striking the waters
backwards and upwards, and assisted probably
by the compression of the air-cells.

Flight, the most important and characteristic
mode of locomotion in birds, results principally
from the construction and form of the anterior
extremities, which have already been described.

The form of the body has also especial
reference to this power, the trunk being an
oval with the large end forwards. The spine
being short and inflexible, the muscles act
to great advantage, and the centre of gravity
is more easily changed from above the feet
as in the stationary position, to between the
wings as during flight. The head of the bird
is generally small, and the beak pointed, which
is a commodious form for dividing the air.
The long and flexible neck compensates for the
want of hands and the rigidity of the trunk,
and contributes to change the centre of gravity,
according to the required mode of progression,
by simply projecting the head forwards, or
drawing it back. The position of the great
pectoral muscles, as before observed, always
tends to keep the centre of gravity at the in-
ferior part of the body. The power which
birds enjoy of raising and supporting them-
selves in the air is undoubtedly aided by the
lightness of the body. The large cavities in
the bones diminish their weight without taking
away from their strength,—a hollow cylinder
being stronger than a solid one of the same
weight and length. But the specific levity
principally depends on the great air-cells, which
occupy almost every part of the body, and
which are all in communication with the
lungs. The air which birds inspire distends
these cells, being expanded by the great heat
of the body. Lastly, the feathers, and especi-
ally the quills, from their lightness and elastic
firmness, contribute powerfully to the act of
flying by the great extent which they give to the
wings, the length and breadth of which are fur-
ther increased by the expanded integument
situated in the bend of the arm and in the
axilla.

When a bird commences its flight it springs
into the air, either leaping from the ground, or
precipitating itself from some elevated point.
During this action it raises the humerus, and
with it the entire wing, as yet unfolded ; it next
spreads it horizontally by an extension or ad-
duction of the fore-arm and hand ; the greatest
extent of surface of the wing being thus acquired,

298

itis rapidly and forcibly depressed; the resistance
of the air thus suddenly struck occasions a
reaction on the body of the bird, which is
thereby raised in the same manner as in leap-
ing from the ground. The impulse being once
given, the bird folds the wings by bending the
different joints, and raises it preparatory to
another stroke.

Velocity of flight depends upon the rapidity
with which the strokes of the wings suc-
ceed each other. A simple downward stroke
would only tend to raise the bird in the air;
to carry it forwards the wings require to
be moved in an oblique plane, so as to strike
backwards as well as downwards. The turn-
ing in flight to the right or to the left is prin-
cipally effected by an inequality in the vibra-
tions of the wings. To wheel to the right the
left wing must be plied with greater frequency
or force, and vice versa.

The outspread tail contributes to sustain
the posterior part of the body ; when depressed
during a rapid forward flight, the anterior part
of the body is raised, and flight retarded ;
when the tail is raised the anterior part of the
body is lowered. Some birds bend the tail to
one side, using it as a rudder when the hori-
zontal course of flight is required to be changed.

The first launch of the bird into the air is pro-
duced by an ordinary leap from the ground,
and depends, in some degree, on the length
of the legs. Those birds which have ye
short legs and very long wings, as the Swallows,
&e., cannot leap high enough to gain the
requisite space for the expansion of their wings,
and consequently have much difficulty in raising
themselves from the ground, and generally pre-
fer throwing themselves from some high point.
The manner of flight varies exceedingly in
different birds, some dart forward by jerks,
closing their wings every three or four strokes ;
the Woodpeckers, Wagtails, and most of the
small Insessores. are characterized by this kind
of undulatory motion : other birds, as the Swal-
low, Crow, &c. fly smooth and even: the Kite
and Kestrel Hawk and the great Albatross some-
times appear to buoy themselves in the air with-
out any perceptible motion of the wings.

The rapidity with which a strong Bird of Prey
flies in pursuit of his quarry is inconceivably
great. The anecdote of the Falcon belonging to
Henry IV. King of France, which flew in one
day from Fontainbleau to Malta, a distance of
1350 miles, is well known, and many similar
instances are on record. The flight of a Hawk,
when its powers are fully exerted, is calculated
at one hundred and fifty miles an hour. The
Kider-Duck’s usual flight has been ascertained
to be at the rate of ninety miles an hour.

The famous Race-horse Eclipse is said to
have gone at the rate of a mile in a minute for
a very short distance; but this speed, if it
could be continued, would not be half so
great as that which many birds put in practice
during their long journeys of migration.

Of the Nervous System.—There is a remark-
able uniformity in the form and structure of the
brain (fig. 134,.a,b,c,d) and medulla spinalis
(e,e) in the different orders of birds. These great

; AVES.

‘Spinal axis are always

longer characteristic of the

divisions of the cerebro-

readily distinguishable
from one another by the
greater breadth and glo-
bular form of the brain,
which is proportionally
much larger than in the
other oviparous verte-
brata. The high degree
of development which
the spinal cord and
cerebellum present, as
compared with the cold-
blooded Reptilia, has
an. evident relation to
the extraordinary loco-
motive powers with which
the feathered class is en-
dowed.

In a Pigeon weighing
eight ounces with, and
seven ounces without its
feathers, or three thou-
sand three hundred and
sixty grains, the cerebro-
Spinal axis weighs forty-
eight grains, the weight
of the spinal cord be-
ing eleven, and that of
the brain thirty-seven
grains.

Of the Brain.—The
brain of the bird differs
from that of the reptile
in the superior size of
the cerebrum, and the
more complex structure~ ;
of the cerebellum; it ‘
differs from the brain of
a mammal in the smaller
size of the cerebellum,
resulting from the want
of the lateral lobes, and
in the absence or rudi-
mentary condition of the
fornix; and it differs
from the brain of every
other vertebrate class in
the lateral and inferior
position of the optic lobes
or bigeminal bodies.*

It cannot be at once
distinguished, as Cu-
vier asserts, by being
composers of six out-
ward and visible masses,
Since the two hemi-
spheres, (a, a,) the two |
optic lobes, (6, b,) the }
cerebellum, (c,) andj
medulla oblongata, (d, ) i ,

ht Aiasis} Hues

* We have lately as-
certained that the corpus
callosum is wanting in some

of the marsupial animals;
its presence is therefore no

class mammalia.

Brain and Spinal Cord
of a Goose,

——

AVES. 299

are equally obvious in the brains of reptiles.
They are, however, differently disposed in birds;
the optic lobes, which in reptiles intervene and
are visible between the cerebrum and cerebel-
lum, being in birds displaced, as it were, by
the hemisphere and cerebellum coming into
close contact, so that the optic lobes are pushed
downwards and to one side. The transverse
convolutions of the cerebellum at once distin-
guish, however, the brain of a bird from that
of any reptile and most fishes; but it is a curi-
ous fact that the cerebellum in the sharks is
similarly composed of a vermiform process only,
transversely folded or convoluted.

The cerebral hemispheres sometimes present

the form of a flattened oval, as in the Parrot
tribe, but in general are of a convex cordiform
shape, with the apex directed forward.
Fig. 135. The optic lobes (6,
tee WEEP , Jig. 135) are rounded
tubercles, situated be-
low and behind the
hemispheres, in the la-
teral interspace between
these and the cerebel-
lum. ~

The cerebellum is

Base of the brain of a composed of the middle
Pisteen. lobe only, and is of a
compressed arched form.

The medulla oblongata presents neither a
tuber annulare nor corpora olivaria or pyrami-
dalia, but is a large uniform tract situated be-
tween and behind the optic lobes.

On the lower part of the side of each cere-
bral hemisphere there is a depression which
corresponds to the fissura magna Sylvii, and is
the only appearance which the hemispheres
present of a division into lobes. Elsewhere
there are no traces of convolutions, the cere-
brum in this respect resembling that of Rep-
tiles and Fishes, and some of the least intel-
ligent orders of Mammalia, as the Rodentia,
Marsupiata, and Edentata. The optic lobes
are also devoid of the transverse fissure which
bisects the optic lobes of mammalia.

The cerebellum is marked by close and
transverse anfractuosities, such as characterize
the corresponding portion of the cerebellum in
mammalia, called the vermiform process.

Fig. 136. When the cerebral
Py xy hemispheres are divari-
, cated from each other,
NL (fig. 136,) they are
yt seen to be disunited
» through the whole of
their vertical - extent,
> and to be joined only
ts * by the round anterior
commissure of the

Brain of a Pigeon. brain (k, fig. 136.) In
fact both the corpus callosum and fornix are
wanting ; or at most a rudiment only of the
latter part can be perceived in the brains of
some birds, as the Eagles, Vultures, and Parrots.
The mesial surfaces of the hemispheres, which
are in contact with each other, present a few
strie which diverge from the commissure.
These surfaces are composed of an extremely

thin layer of medullary substance, (g, ) forming
the internal parietes. of the ventricle, and ex-
tended outwardly over the corpus striatum ( i. )
This body is of very great size in birds, consti-
tuting of itself almost the entire substance of
the hemisphere, projecting into the ventricle,
(Ah, ) not only from below, but from the anterior
and outer sides of the cavity, and being covered
by a smooth layer or fold of medullary matter,
(f;) which increases in thickness anteriorly.
The ventricle does not extend below the corpus
striatum to form an inferior horn; and, as in
most mammalia there is no extension of the
cavity backwards to form a_ posterior horn,
there is consequently no cornu ammonis. The
vessel forming the plexus choroides penetrates
the ventricle beneath the posterior part of the
thin internal wall, and the lateral ventricles
communicate together there, and with the third
ventricle. They are continued anteriorly to the
root of the olfactory nerve, which is itself a
continuation of the apex of the hemisphere.

Just above the orifice of communication there
is a smooth flattened projection, rounded exter-
nally, which advances into the ventricle from the
internal wall; this is a rudiment of the fornix.

The round anterior commissure (k) is pro-
longed on either side into the substance of the
hemispheres, as in man and quadrupeds.

The optic thalami (/) are of small size, and
not united by a soft commissure: between them
is the cavity called third ventricle (m); and
above and behind they give off the peduncles
of the pineal gland. This body does not hang
freely suspended by the pedicles, but seems to
fori a rounded and thickened anterior border
of the valvula Vieussenii or lamelliform commis-
sure of the optic lobes. Carus describes the
pineal gland as adhering firmly to the conflu-
ence of the great veins situated at the anterior
orifice of the aqueduct of Sylvius. In Pigeons
he states that it is composed of many segments,
but that in general it is of a simple and conical
form; the figure which he gives of it, from the
Turkey, exhibits a pyriform shape.* The valve
which closes the upper part of the passage
from the third to the fourth ventricle, is a thin
lamella of great width, in consequence of the
distance to which the optic lobes are sepa-
rated from one another. Anteriorly the third
ventricle communicates with the infundibulum.

The fourth ventricle (7) resembles that in
the brain in mammalia, but is of less width;
its floor is indented with the longitudinal fissure
called calamus scriptorius.

Besides the cavities or ventricles above men-
tioned, there are also two others situated in the
optic lobes (0), or bigeminal bodies, each of
which, when laid open, is seen to be occupied
by a convex body (p) projecting from the
posterior and internal side of the lobe; these
ventricles communicate with the others in the
aqueduct of Sylvius.

As there is no transverse furrow in the optic
lobes, they cannot be distinguished into the
protuberances called ‘ nates’ and ‘ testes’ in

* Anat. Comparée, nouv. ed. i. p. 88, pl. xv.
fig. 6.

300 AVES:

the human brain; they have most resemblance,
however, to the latter bodies.

With respect to the substance of which the
brain of birds is composed, we may observe
that the bodies analogous to the corpora striata
do not merit that name, as there are no alterna-
ting strie of grey and white matter. In this
respect the bird’s brain resembles that of the
cold-blooded ovipara and of the human feetus.
The substance of the cerebellum does present
the admixture of the two substances, or arbor
vite (q ), but in a less complicated degree than
in mammalia.

The brain in birds is invested with the same
membranes as are described in Mammalia.

Medulla spinalis——The spinal cord is con-
tinued from the foramen magnum to the canal
formed by the coccygeal vertebre, where, how-
ever, it becomes extremely attenuated, and
corresponds in extent to the shortness of that
division of the vertebral column, terminating
in a mere filament which expends itself in
distributing a few pairs of nerves through the
coccygeal foramina. As in the Mammalia, it
appears externally to be composed of the white
or medullary matter, but contains a small pro-
portion of grey substance internally. It is of
a cylindrical figure, and as in the cold-blooded
Ovipara, it is of great length in proportion to
the brain. An anterior and posterior fissure
may be distinguished, and also a narrow canal
which extends through its entire length. Two
enlargements occur in the conrse of the spinal
cord, one corresponding to the wings, the
other to the legs; and from these swellings
the nerves of the brachial and sacral plexuses
come off respectively. As might be expected,
therefore, these enlargements present differ-
ences of relative size corresponding to the dif-
ferent relative development and powers of the
anterior and posterior extremities. In general
the posterior enlargement is greater than the
anterior; and this difference is very remarkable
in the Struthious birds in which the whole
business of progression falls upon the posterior
extremities.

Besides the difference in size, the spinal
enlargements or ganglions, as they may be
termed, differ also in structure; at the anterior,
alar, or thoracic enlargement (7, fig. 134) the
spinal cord merely receives an accession of
grey and white medullary substance; but at
the beginning of the sacral swelling (s, fig. 134)
the canal of the cord enlarges in a remark-
able manner, so that the lateral cords separate
from one another posteriorly or above, pre-
cisely as they do to form the fourth cerebral
ventricle: the cavity or spinal ventricle (s,
Sig. 134) thus formed, is filled with a serous
fluid inclosed in a pia mater. From the figure
of this cavity it has been termed the ‘ Sinus
rhomboidalis.’

Of the Nerves.—The cerebral nerves cor-
respond in number to those of the Mammalia.
The principal difference of form and structure
is presented in the olfactory or first pair
(1, jig. 135.) These nerves are of a cylin-
drical figure and small extent, being continued
from the anterior extremity or apex of the

hemispheres. Instead of separating into fila~
ments to pass out of the skull by a cribriform
lamella, each nerve is continued along an
osseous canal, accompanied by a venous trunk,
as far as the pituitary membrane of the supe-
rior spongy bone upon which its filaments are
distributed in a radiated manner. .

The optic nerves (2, figs. 135, 137,) are in
general of remarkable size ; they arise from the
whole of the outer surface of the optic lobes,
and form in front of the infundibulum, a perfect
union, or chiasma, (2*, fig. 137,) in which, on
making a horizontal section, some transverse
strie may be perceived, apparently resulting
from the decussating fibrils of the nerves.

The distribution of the third, (3, figs. 135,
137,) fourth, (4, figs. 135, 137,) and sixth
cerebral nerves, (6, figs. 135, 137,) is almost
the same as in Mammalia. The course of the
fourth pair, immediately above the supra-
orbital branch of the fifth pair is shown at
4*, fig. 137, as far as its termination in the
superior oblique muscle to which it is, as in
other vertebrata, exclusively distributed.

The fifth or trigeminal nerve (5, figs. 135,
137) has nearly the same distribution as in
Mammalia.

The first or ophthalmic division (5*, fig. 137)
passes out of the cranium by a peculiar canal
situated externally to the optic foramen. It is of
large size, and describes in its passage through
the orbit a curve corresponding to the roof of
that cavity; it generally penetrates the substance
of the facial bones above the nasal fosse. It
divides into three branches ; the first or supe-
rior is the smallest and is lost upon the pitui-
tary membrane; the second branch is the
largest of the three and the longest; it is re-
ceived into an osseous canal, passes over the
nasal organs, and terminates at the extremity
of the beak in a great number of divisions;
the third branch of the ophthalmic nerve is
entirely distributed to the skin which covers
the circumference of the external nestrils.

The second division, or supérior maxillary
nerve passes out of the same foramen as the in-
Jerior one (at 5”, fig. 137,) immediately above
the tympanic bone or os quadratum ; it passes
forwards along the floor of the orbit, and in
this part of its course gives off two filaments,
of which one joins the ramifications of the
ophthalmic nerve, the other ascends, penetrates
the substance of the pterygoid muscles and
the maxillary bone, to be lost on the lateral
parts of the bill. In those birds, as the
Anatide and other Water-fowl, where the upper
mandible is notched on the edge, each denticu-
lation receives four or five nervous filaments,
and the nerve is proportionally of large size.

The inferior maxillary nerve separates from
the superior, and proceeds obliquely down-
wards, dispensing branches to the pterygoid
and quadrangular muscles of the jaws; the
trunk proceeds outwards to the lower jaw
where it divides into two branches an internal
and an external. The internal, which is a con-
tinuation of the trunk, penetrates the maxillary
canal, and is continued to the anterior end of
that mandible. In the Anatide it gives off

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AVES,

nerves to the dentations along the edge of the
mandible. The external branch recedes from
the internal, perforates the jaw, and is dis-
tributed on its external surface beneath the
tegumentary or horny substance which sheaths
the extremity of the mandible. It supplies no
gustatory branch to the tongue, which is an cr-
gan of prehension, not of taste, in Birds.

‘The facial nerve, or portio dura, exists in
Birds, but it is extremely small, its offices
being hardly required, in consequence of the
structure of the parts of the face in this class.
However, a few branches may, with difficulty
indeed, be traced, and the trunk of the nerve is
constantly present.

The auditory nerve, or portio mollis, is large,
very soft and pulpy, and of reddish colour ;
it 1s received into a deep depression on the
internal surface of the cranium (at 7, fig. 137),
whence it penetrates by several small foramina
to the labyrinth.

The pneumogastric nerve, or nervus vagus,
generally passes out of the cranium in two or
three filaments, which afterwards rejoin. On
leaving the skull, this nerve communicates
with the lingual and glosso-pharyngeal nerves.
and is situated between them, the lingual being
placed in front. Each nerve of the par vagum
passes as a distinct strong cord along the neck
in company with the jugular vein, and de-
scending into the chest forms the cardiac and
pulmonary plexuses, as in Mammalia. The
two nerves unite behind the heart, and proceed
along the esophagus to terminate in anasto-
moses with the great sympathetic nerve.

The glosso-pharyngeal nerve of the eighth
pair passes out of the cranium through the
foramen behind the ear, which corresponds to
the foramen lacerum posterius, by two filaments,
which immediately unite to form an elongated
quadrangular ganglion ; this sends off a small
internal branch in front of the muscles of the
neck; a small posterior twig which unites with
the par vagum, and a large inferior branch to
the anterior part of the neck. The latter is a
continuation of the nerve itself; it descends
along the cesophagus and divides into two prin-
cipal branches, of which one passes upwards
to the muscles of the os hyoides, between
which it is included, and this branch is re-
markably tortuous in the Woodpecker in order
to be accommodated to the extensile motions of
the tongue. The other branch descends along
the lateral parietes of the csophagus, and
sends off a twig to join the lingual nerve.
The termination of the glosso-pharyngeal is
expanded upon the esophagus.

The hypoglossal nerve (9th pair) escapes
from the cranium posterior to the nervus vagus
by the condyloid foramen. It is very slender
at its origin; passes to the front of the nervus
vagus, partly uniting with, as it crosses over this
nerve, and in that situation it detaches a small
filament analogous to the descendens noni,
which accompanies the jugular vein to the
chest. The trunk of the hypoglossal next
crosses the glosso-pharyngeal nerve, then passes
beneath the cornu of the os hyoides, and ad-
‘vances towards the superior larynx, where it

301

terminates by dividing into two principal
branches, which are distributed, the one to the
anterior and inferior, the other to the superior
and internal parts, of the tongue.

Spinal nerves,—These correspond in number
to the vertebre of the spine. ‘They arise, as in
the other vertebrata by two roots, the ganglion
on the posterior of which is proportionally very
large. Inthe sacral region of the spine, the
anterior and posterior roots escape by distinct
foramina, and can be separately divided with-
out laying open the bony canal, but they are
deeply seated and well protected by the anchy-
losed processes of the sacrum and the extended
iliac bones.

The cervical nerves vary considerably in
number, the known extremes being from ten
to twenty-three, corresponding to the number of
vertebre. They are proportionally larger than in
man, are tortuous in their course, to be accom-
modated to the extensive motions of the neck,
and are principally lost in the integument.
Only the last, or last two, pairs (w’ wv’, fig. 134)
of cervical nerves concur in the formation of
the brachial plexus, which is completed by the
first two pairs of dorsal or thoracic nerves (v ).

The dorsal nerves do not present any notable
differences from those of mammalia.

The sacral nerves have no other peculiarity
than their mode of passing out of the spinal
canal: they form exclusively the plexus ana-
logous to the lumbar and sacral (w, fig. 134).

The nerve analogous to the phrenic nerve is
wanting in Birds, in correspondence with the
rudimentary condition of the diaphragm.

The brachial plexus, formed by the two last
cervical and one or two first dorsal nerves, soon
becomes blended into a single fasciculus whence
all the nerves of the wing are derived. Accord-
ing to Cuvier, the first four that are given off
are of large size, and are distributed to the
great and middle pectoral and subclavian mus-
cles. A small filament is then detached which
supplies the muscles surrounding the head of
the humerus and capsule of the joint; this re-
presents the articular nerve. The rest of the
plexus divides into two large nerves, which
supply the wing.

Macartney describes the course of the nerves
of the wing in a somewhat different manner,
and observes that they more nearly resemble
those of the superior extremity in mammalia,
than Cuvier has represented. The brachial
plexus, according to this author, gives rise to
three nerves which are distributed in the follow-
ing manner :—“ The first isa very fine filament,
which runs down on the inside of the arm, and
is lost about the internal part of the elbow.
This is analogous to the internal cutaneous
nerve. The second is a large cord; it gives
off a very large branch, which divides into
many others, for the supply of the pectoral
muscles ; it.sends several smaller branches to
the muscles under the clavicle and about the
joint, and then proceeds to the inner edge of
the biceps muscle, along which it descends to
the fold of the arm, after giving some large
muscular branches. Before it reaches the
joint, it divides into two branches; one of

302

which is analogous to the ulnar nerve, and the
other soon divides again into nerves which are
similar to the median and musculo-cutaneous.
The median dips down amongst the muscles on
the middle of the fore-arm, to which it gives
branches, and afterwards runs along the inter-
osseous space, passes under the annular ligament
of the carpus, and is distributed to the short
muscles of the digiti. The branch analogous to
the musculo-cutaneous nerve, is expanded upon
the muscles on the upper edge of the radius.

“¢ The ulnar nerve, although it appears to be
incorporated with the median on the upper arm,
can be easily separated from it, and traced to its
proper origin in the brachial plexus. After this
nerve leaves the median, it turns over the end
of the foramen to get upon the edge of the
ulna. It gives filaments to the muscles in this
situation; but its chief branch runs down
superficially upon the ligaments of the quills in
company with a vein, and goes ultimately to
be lost upon the ulnar edge of the hand.

“ The third cord furnished by the brachial
lexus, supplies the place of the radial nerve.
t detaches several filaments to the muscles on

the inside and back of the scapula. It gives
off also the articular nerve, and then winds
round the humerus between the extensor mus-
cles, to which it furnishes some large filaments.
On coming to the outside of the humerus, it
sends a branch between the integuments of the
fold of the wing. ‘The nerve now turns round
the neck of the radius, beneath the muscles,
and forms two branches ; of which one passes
under the muscles to the outer side of the ulna,
along which it runs superficially to the hand ;
the other branch passes on the radial side, but
more deeply amongst the muscles, goes under
the annular ligament of the carpus, proceeds
between the branches of the metacarpus, and is
finally lost on the back of the digiti.” Thesame
anatomist describes the course of the nerves of the
posterior extremities as follows.

“« Although Cuvier has given a more accurate
description of the nerves of the lower extremity
than those of the wing, it nevertheless needs
correction in several particulars.

“The obturator and femoral nerves arise
from the same plexus which is formed by the
two last lumbar nerves, by a communicating
branch from the first sacral pair. The obtu-
rator nerve passes through the upper part of the
foramen ovale, and is distributed to the muscles
around the hip-joint, especially the adductor.
The femoral nerve passes out of the pelvis in
company with the artery, over the upper edge
of the ilium. It divides into three branches,
which are dispersed among the muscles and
integuments on the anterior and inner part of
the thigh. Some of these filaments are long,
and descend superficially for a considerable
way upon the limb.

“ The ischiatic nerve is composed of the five
superior sacral nerves; and as soon as it de-
parts from the plexus, even within the pelvis,
is easily separable into its primary branches.
Immediately after it passes through the ischi-
adic foramen, it sends filaments to the muscles
on the outer part of the thigh ; it then proceeds

AVES.

under the biceps muscle, along the back of the
thigh, about the middle of which it becomes
divided into the tibial and the peroneal nerves.

“The tibial nerve, even before it arrives in
the ham, separates into several branches, which
pass on each side of the bloodvessels, and are
chiefly distributed to the muscles on the back
of the leg. Two of these branches, however,
are differently disposed of; the one accom-
panies the posterior tibial artery down the leg,
passes over the internal part of the pulley, and
is lost in small filaments and anastomoses, with
a branch of the peroneal nerve on the inner side
of the metatarsus; the other branch runs down
on the peroneal side of the leg, along the deep-
seated flexors of the toes, passes in a sheath
formed for it on the outer edge of the moveable
pulley of the heel, and proceeds under the
flexor tendons along the metatarsal bone, to be
distributed to the internal part of the two ex-
ternal toes.

“ The peroneal nerve is directed to the outer
part of the leg; it dips above the gastrocnemit
muscles, and runs through the same liga-
mentous pulley that transmits the tendon of the
biceps muscle; it then detaches some large
filaments to the muscles on the anterior part
of the leg, under which it divides into two
branches, which proceed close together, in com-
pany with the anterior tibial artery to the fore
part of the ankle-joint, at which place they
separate; one passes superficially over the
outer part of the joint, the other goes first
under the transverse ligament which binds
down the tendon of the tibialis anticus muscle
on the tibia, and then over the inner part of the
joint, below which it divides into two branches,
the one is distributed to the inner side of the
metatarsus and the tibial side of the pollex,
and to the next toe; the other turns towards
the centre of the metatarsal bone, and pene-
trates the tendon of the tibialis anticus just
at its insertion, and then rejoins the branch
of the peroneal nerve it accompanied down the
leg. They continue their course together again
in the anterior furrow of the metatarsal bone ;
and at the root of the toes, separate once more,
and proceed to the interspaces of the three
anterior toes, and each divides into two fila-
ments, which run along the sides of the toes to
the nail.” — Rees’ Cyclopedia, Art. Birds.

The great sympathetic nerve of birds resem-
bles, in many particulars, that of mammals.
It enters the cranium by the same orifice as
that by which the nervus vagus and the glosso-
pharyngeal make their exit; it there unites
with the fifth and sixth pair of nerves. At the
base of the cranium the first ganglion, or su-
perior cervical, is of a lenticular form, and
communicates at once with the ninth and eighth

airs of nerves, so as to seem as if it were

lended with them. The remainder of the
chain of cervical ganglions are very remarkably
situated, being lodged on either side in the
canal of the vertebral artery formed by the trans-
verse processes ; into which it passes, or from
which it escapes above, at the third cervical
vertebra, while below the sympathetic again
becomes conspicuous at the commencement of

AVES.

the thorax, where it sends a considerable branch
from the first thoracic ganglion to join the pul-
monary plexus formed by the par vagum.
This ganglion also distributes seven other fila-
ments, one of which goes to join the brachial
plexus; a second is lost in the cardiac plexus of
the par vagum ; three other filaments proceed
inwardly to the projection formed by the bodies
of the vertebree to produce the commencement
of the splanchnic nerve ; lastly, the sixth and
seventh serve to unite the first ganglion with
the second, one passing above, the other below
the head of the rib, which they thus include in
a lozenge-shaped space. Each of the succeed-
ing ganglions forms, in like manner, a centre of
nervous radiations, which are five, six, or seven
in number, of which four, two anterior and two
posterior, serve to bring the contiguous ganglia
into communication with each other; one or
two contribute to the formation of the splanch-
nic nerve, and one joins the dorsal spinal nerve
situated immediately behind the ganglion.

The splanchnic nerves, formed by all the in-
ternal thoracic branches of the great intercostal,
accompany on either side the trunk of the
aorta. When it has arrived at the cceliac axis,
they surround it and form one, two, or three
ganglions from which an immense number of
filaments are thrown off, which surround the
different arteries of the abdomen. These gang-
lions are evidently the analogues of the semi-
lunar ganglions of man, and the filaments pro-
ceeding from them correspond to the solar
plexus. The trunk of the sympathetic con-
tinues along the bodies of the vertebrae, but
the ganglions become less marked after the ribs
cease to be given off; two or three filaments
are given off from each of these small swell-
ings, which, by uniting with the filaments of
the opposite side, form a plexus around the
aorta. The termination of the sympathetic may
be readily traced along the coccyx, where four
pairs of ganglions are observable in the Swan,
the last of which join to form a ganglion impar.

Cerebral nerves, eyes, Sc. in situ of a Goose.

303

Organs of Vision.—The eye in Birds pre-
sents many peculiarities, which chiefly relate to
the extraordinary powers of locomotion in this
class, tending to accommodate vision to a rapid
change of distance in the objects viewed, and
to facilitate their distinct perception through a
rare medium.

There is no species of bird in which the eyes
are wanting, or are rudimentary, as occurs in
the other vertebrate classes.

The eyes of Birds are, in the first place, re-
markable for their great size, both as compared
with the brain and with the entire head, (fig.
137,) being analogous, in this respect, to the
eyes of some of the flying insects. Their form
is admirably adapted to promote the objects
above named. ‘The anterior segment of the
eye is more prominent than in any other class
of animals, and is in many birds prolonged into
a tubular form, terminated by a very convex
cornea (¢, fig. 137.) Dr. Macartney observes
that * the owl furnishes the most striking ex-
ample of the disproportion between the anterior
and posterior spheres of the eye, the axis of the
anterior portion being twice as great as that of
the other. The obvious consequence of this
figure of the globe of the eye is to allow room
for a greater proportion of aqueous fluid, and
for the removal of the chrystalline lens from the
seat of the sensation, and thus produce a greater
convergence of the rays of light, by which the
animal is enabled to discern the objects placed
near it, and to see with a weaker light; and
hence ow/s, which require this sort of vision so
much, possess the structure fitted to effect it in
so remarkable a degree.”

The anterior division of the eye is least con-
vex in the swimming birds. The sclerotic
coat is divisible into three layers. It is thin,
flexible, and somewhat elastic posteriorly, where
it presents a bluish shining appearance, without
any distinct fibres, but anteriorly its form ismain-
tained by a circle of osseous plates or scales (f,
JSig.137) interposed between the exteriorand mid-
dle layers. These plates vary from thirteen to
twenty in number, and are situated immedi-
ately behind the cornea, with their edges over-
lapping each other. They are in general thin,
and of an oblong quadrate figure, becoming
elongated from before backwards in proportion
as the bird possesses the power of changing the
convexity of the cornea. In the nocturnal
Raptores the bony plates are strong and thick,
and extend from the cornea over the whole of
the anterior projecting division of the eye to the
avengiatd hemisphere, which they also contri-

ute to form. The figure of the eye is thus
maintained, notwithstanding its want of sphe-
ricity; and in other classes, as Reptiles and
Fishes, where the eye recedes from the spherical
figure from an opposite cause, viz. the extreme
flattening of the cornea, that form is also pre-
served by the introduction of an osseous struc-
ture in the sclerotic.

The bony plates are capable of a degree of
motion upon each other, which is, however,
restrained within certain limits by the attach-
ments of their anterior and posteriof edges to
the sclerotic coat; and by their being bound

304 AVES.

together with a tough ligamentous substance,
which seems to be the continuation of the scle-
rotic between the edges that overlap each other.

The cornea possesses the same structure as
in mammalia, but differs with respect to form.
When the posterior part of the eye is com-
pressed by the muscles, the humours are urged
forwards and distend the cornea ; which, at that
time, becomes much more prominent in most
birds than it is ever observed in mammalia ;
and under such circumstances, the eye is in a
state for perceiving near objects. When the
muscles are quite relaxed, the contents of the
eye-ball retire to the posterior part, and the
cornea becomes flat or even depressed: this is
the condition in which we always find the eye
of a dead bird, but we can have no opportunity
of perceiving it during life. It is only prac-
tised for the purpose of rendering objects visi-
ble that are placed at an extreme distance.
From the well-known effects of form upon re-
fracting media, it must be presumed, that the
cornea possesses very little, if any, convexity,
when a bird which is soaring in the higher re-
gions of the air, and invisible to us, discerns its
prey upon the earth, and descends with uner-
ring flight to the spot, as is customary with
many of the rapacious tribe.

The degree of convexity of the cornea is also
changed in birds by the action of muscular
fibres especially appropriated to its motions.
These were discovered by Crampton ; are dis-
posed around the circumference of the cornea,
and are attached to its internal layer; they
draw back the cornea, in a manner analogous
to the action of the muscles of the diaphragm
upon its tendinous centre.

The choroid coat re-
sembles in its structure
that of mammalia; it
is copiously covered
with a black pigment,
similar to that in the
human eye. Opposite
the bony circle the
choroid separates into
two layers; the exter-
nal layer is the thin-
nest, and adheres at first firmly to the sclerotica,
after which it is produced freely inwards to
form, or be continuous with, the iris.

The iris (e, fig. 138) is delicate in its texture,
which under the lens appears composed of a fine
net-work of interlacing fibres, but itis remarkable
for the activity and extent of its movements,
which seem in many birds to be voluntary. The
contraction and dilatation of the pupil, inde-
pendent of any change in the quantity of light
to which the eye is exposed, is most conspicu-
ous and remarkable in the Parrot tribe, but we

have observed it also in the Cassowary and
some other birds.

The colour of the iris is subject to many

varieties, which frequently display great bril-
liancy, and afford zoologists distinguishing spe-
cific characters of birds; although these cannot
always be implicitly relied upon.

The breadth of the iris varies in different
species, but is greatest in Birds which take

their food in the gloom of evening, as the.
Owls and Night-jar, in order that the pupil
may be praporyonayy enlarged to admit as
much light as possible to the retina. Carus
observes that in the eye of the Owl is exhibited
with peculiar distinctness the remarkable dis-
tribution of the ciliary nerves and vessels, which,.
rnnning in the form of single trunks between
the choroid and sclerotica, terminate anteriorly in
several ring-shaped plexuses for the supply of
the iris and of the muscular circle of the cornea.
The pupil is usually round: in the Goose and
Dove it is elongated transversely, and in the
Owls is vertically oval.

The inner layer of the choroid is thicker than
the external, and is disposed in numerous
thickly set plice radiating towards the anterior
part of the chrystalline lens, where they termi-
nate in slightly projecting ciliary processes, (d,
Jig.138,) the extremities of whichadhere firmly to
the capsule of the chrystalline. These processes
are the most numerous, close set, and delicate in
the Owl; they are proportionally larger and
looser in the Ostrich.

The chief peculiarity in the eye of the Bird
is the marsupium or pecten, (f, fig. 138,) which
is a plicated vascular membrane analogous in
structure to the choroid, and equally blackened
by the pigmentum; situated in the vitreous
humour anterior to the retina, and extending
from the point where the optic nerve penetrates
the eye to a greater or less distance forwards,
being in many birds attached to the posterior
part of the capsule of the chrystalline. As its
posterior point of attachment is not to the
choroid but to the termination of the optic.
nerve, this requires to be first described.

When the optic nerve arrives at the sclerotic,
it tapers into a long conical extremity, which
glides into a sheath of a corresponding figure,
excavated in the substance of that membrane,
and directed downwards and obliquely forwards.
The central or inner layer of this sheath is split
longitudinally, and the substance of the nerves
passes through this fissure. A similar but
longer fissure exists in the corresponding part
of the choroid: so that the extremity of the
optic nerve presents in the interior of the eye,
instead of a round disc, as in mammalia, a
white narrow streak, from the extremities and
sides of which the retina is continued. Branches
of the ophthalmic artery, which are quite dis-
tinct from the vessels of the choroid, and ana-
logous to the arteria centralis retine, enter the
eye between the lamine of the retina, along the
whole extent of the oblique slit above men-
tioned, and immediately enter or compose the
folds of the marsupial membrane, upon which
they form most delicate and beautiful arbore-
scent ramifications.

The marsupium is lodged like a wedge in
the substance of the vitreous humour, in a
vertical plane, directed obliquely forwards. In
those species in which the marsupium is widest,
the angle next the cornea reaches the inferior
edge of the capsule of the chrystalline; but
where it is narrow, the whole anterior surface
is in contact with the same point. This con-
tact is so close in some birds, as the Vulture,

Ail Ks 5 “bbw, i UM SSL Phy

AVES.

Parrot, Turkey, Cassowary, Stork, Goose, and
Swan, that the marsupium seems absolutely to
adhere to the capsule of the lens; but in many
other birds, on the contrary, it does not extend
further than two thirds of the distance from
the back part of the eye, and is attached at its
anterior extremity to some of the numerous
lamine of the hyaloid membrane which form
the cells for the lodgment of the vitreous hu-
mour. In these cases the marsupium can
have no influence on the movements of the
lens, unless it be endowed with an erectile
roperty, and be so far extended as to push
orward the lens. The researches of Bauer*
have shewn that there is no muscular structure
in the marsupium, and its changes of form,
if such occur in the living bird, must be
effected by changes in the condition of the
vessels of which it is almost exclusively com-
posed.

The form of the marsupium varies in differ-
ent birds ; it is broader than it is long in the
Stork, Heron, Turkey, and Swan; and of the
contrary dimensions in the Owl, Ostrich, and
Cassowary. The plice of the membrane are
perpendicular to the terminal line of the optic
nerve; they are of a rounded figure in most
species, but in the Ostrich and Cassowary they
are compressed, and so far inclined from the
plane of the membrane, that their convergence
towards its extremity gives ita resemblance toa
close-drawn purse.t ‘The folds vary in num-
ber, being four in the Cassowary, seven in the
Great Horned Owl, eight in the Goose, from
ten to twelve in the Duck and Vulture, fifteen
in the Ostrich, sixteen in the Stork, and still
more numerous in the Insessorial Birds,

amounting to twenty-eight, according to Soem-
merring, in the Fieldfare.

The exact functions of the marsupial mem-
brane are still involved in obscurity. Its po-
sition is such that some of the rays of light
proceeding from objects laterally situated with
respect to the eye must fall upon and be
absorbed by it; and Petit accordingly supposed
that it contributed to render more distinct the
|. in of objects placed in front of the eye.

e theory originally proposed by Sir Everard
Home,} which attributed to the marsupium the
office of retracting the lens for the purpose of
distant vision by its muscular contraction, is
opposed by the numerous examples in which

* Philosophical Transactions, 1822, p. 76.

+ The Parisian Academicians, who took their de-
scription of this part from the Ostrich, first applied
to it the name of M ium or Bourse. The origi-
nal description is as follows:—‘* De cét entonnoir
(the termination of the optic nerve) sortoit une
membrane plissée, faisant comme une bourse qui abou-
tissoit en pointe vers le bord du Christallin le plus
prochain de !’entrée du nerf optique. Cette bourse,
= estoit large de six lignes par le bas, a la sortie

u nerf optique, et qui alloit en pointe vers le hant,
estoit attachée par sa pointe au bord du Chrystallin,
par le moyen de la membrane qui le couvroit du
costé de Vhumeur vitrée, et qui couvroit aussi toute
la bourse qui estoit noir mais d’un autre noir que
n’est celuy de la choroide.”—-Duvernoy, in ‘ Mé-
meee pour servir a ]’Hist. Nat. des Animaux,’
t Croonian Lecture, Phil. Trans. 1796,

VOL. I.

305

it does not extend to the chrystalline, and by
the manner of its attachment in those cases in
which it does; since, as in these the mar-
supium adheres to the side of the chrystalline,
it can only move it obliquely.

Some physiologists have supposed that this
black membrane was extended towards thecentre
of the eye, where the luminous rays are most
powerfully concentrated in order to absorb the
excess of intense light to which birds are ex-
posed in soaring aloft against the blazing sun.
Others have considered it as the gland of the
vitreous humour, and that, as this fluid must
be rapidly consumed during the frequent and
energetic use made of the visual organ by
Birds, it therefore might require a superadded
vascular structure for its reproduction.

We are inclined to consider the marsupium
as an erectile organ, adapted to receive a vary-
ing quantity of blood, and to occupy a variable
space in the vitreous humour; when fully in-
jected, therefore, it will tend to push forward
the lens, either directly or through the medium
of the vitreous humour, which must be dis-
placed in a degree corresponding to the in-
creased size of the marsupium ; the contrary
effects will ensue when the vascular action is
diminished. From the analogy of other struc-
tures introduced by Supreme Wisdom into the
mechanism of organized bodies, it may reason-
ably be supposed that the marsupium is not
limited to a single function.

The retina is continued from the circumference
of the base of the marsupium, and after forming
a few slight folds expands into a smooth layer
of medullary matter, which seems to terminate
at the periphery of the corpus ciliare. In the
Owls, as Haller has observed, not more than
half the globe of the eye is lined by the retina;
it ceases in fact where the eye loses the sphe-
rical form at the base of the anterior cylindrical
portion.

The humours of the eye no less correspond
to the peculiar vision of the bird, and the rare
medium through which it is destined to move,
than the shape of the globe and the texture of
its coats.

The aqueous humour is extremely abundant,
owing to the extent of the anterior chamber
gained by the convexity of the cornea, and
its refractive power must be considerable in the
higher regions of the atmosphere. The mem-
brane inclosing it can be more readily demon-
strated in birds than in most mammals, espe-
cially where it adheres to the free edge of the
iris.. The large size of the ciliary processes
may have the same relation to the repro-
duction of the aqueous, as the marsupium is
supposed to have with reference to the vitreous
humour.

The chrystalline lens is remarkable for its flat-
tened form, especially in the high-soaring
Birds of Prey; it is also of a soft texture, and
is without any hard nucleus, as in the eyes
of Fishes and Reptiles. In the Cormorant
and other birds which seek their food in
water, the chrystalline is of a rounder figure,
and this is peculiarly the case in the near-
sighted Owls which hunt for prey in obscure

x

306

light. It is inclosed, as in Mammalia, in a
distinct capsule, which adheres very firmly to
the depression in the anterior part of the
vitreous humour; the capsule is itself lodged
between two layers of the membrana hyaloidea,
which, as they recede from each other to pass—
the one in front and the other behind the lens,
—leave round its circumference the sacculated
canal of Petit.

The vessels of the lens are derived from
those of the marsupium, which, as we have
before observed, are ramifications of the analogue
of the arteria centralis retinee. With respect to
this vessel we may here observe, that it is not
continued as a simple branch from its origin to
the marsupium,—such a course would be in-
consistent with the important functions it is
destined to fulfil in the present Class. Imme-
diately before penetrating the coats of the eye
it breaks into numerous subdivisions, the aggre-
gate of which is much greater than the trunk
whence they proceed, and these again unite,
forming a plexus (e, fig. 139) close to the ex-
ternal side of the optic nerve. The artery of
the marsupium proceeds from this plexus, and
runs along the base of the folds, giving off at
right angles a branch to each fold, which in
like manner sends off smaller ramuli. The
plexus at the origin of the marsupial artery
serves as a reservoir for supplying the blood
required for the occasional full injection of the
marsupium ; and a similar but larger plexus
(4, fig. 139) is formed at the origins of the
ciliary arteries which supply the erectile tissue
of the ciliary processes and iris. These plexuses
are described by Barkow, from whose Memoir®
the subjoined figure is taken, but their relation
to the erectile powers of the parts they supply
appears to have escaped his notice.

The vitreous humour presents few peculia-
rities worthy of note ; compared with the aque-
ous humour, it is proportionally less in quan-
tity than in the eyes of Mammalia. The outer
capsule formed by the hyaloid membrane is
stronger, and can be more easily separated
from the humour.

The Eye-ball
is moved in Birds
by four straight
and two oblique
muscles. The
Recti muscles a-
rise from the cir-
cumference of the
optic foramenand
expand, as they
pass forward, to
be inserted into
the soft middle
part of the scle- Muscles of the eye.
rotic. We have not been able to trace their
insertion distinctly to the osseous circle;
their aponeurosis cannot be reflected for-
wards from the sclerotica without lacerating
that membrane.

The Obliqui both arise very near together
from the anterior parietes of the orbit, and go

* Meckel’s Archiven, B. xii, pl. x.

AVES.

to be inserted, the one into the upper, the other
into the lower part of the globe of the eye; the.
superior obliquus does not pass through a
pulley, as in Mammalia. Be

All the muscles are proportionally short in
this class, but especially so in the Owls, in
which the eye, from its large size and close
adaptation to the orbit, can enjoy but very little
motion. ;

In the subjoined figure and in fig. 140,
a’ is the rectus superior or attollens; b’ the
rectus inferior or deprimens; c’ the rectus ex-
ternus or abducens; d’ the rectus internus or
adducens ; e the obliquus superior ; i. the ob-
liquus inferior ; g’ the quadratus ; fh’ the pyra-
midalis.

The accessory pee of the eye in Birds are
similar to those of the higher Reptiles. There
are three eye-lids, two of which move vertically,
and have a horizontal commissure, while the
third, which is deeper-seated, sweeps over the
eye-ball horizontally, from the inner to the
outer side of the globe. The vertical, or upper
and lower eye-lids, are composed of the com-
mon integument, of a layer of conjunctiva, and
between these of a ligamentous aponeurosis,
which is continued into the orbit, and lines the
whole of that cavity. The lower eye-lid is the
one which generally moves in closing the eye in
sleep, and it is further strengthened. by means
of a smooth oval cartilaginous plate, which is
situated between the ligamentous and con-
junctive layers.

The orbicularis muscle is so disposed as by
means of this plate to act more powerfully in
raising the lower than in depressing the upper
eye-lid. In the latter it is continued imme-
diately along the margin: in the lower eye-lid
the tarsal cartilage intervenes between the mus-
cle and the ciliary margin.

The levator palpebre superioris arises from
the roof of the orbit, and is inserted near the
external angle of the lid.

There is also an express muscle for depress-
ing the lower eye-lid, as in the Crocodile.

In the Owls and Night-jar ( Caprimulgus )
the eye-lids are closed principally by the depres-
sion of the upper one. There are but few birds
that possess eye-lashes ; of these the Ostrich is
an example, as also the Horn-bills and the Owls,
in which they are arranged in a double series ;
but in these they are rather to be considered as
feathers with short barbs, than true eye-lashes.

The third eye-lid, or membrana nictitans, is
a thin membrane, transparent in some birds,
in others of a pearly white colour, which,
when not in action, lies folded back by virtue
of its own elasticity on the inner or nasal side
of the globe of the eye, with which it is in close
contact.

Two muscles are especially provided to effect
its movements, but are so placed as to cause
no obstruction to the admission of light to the
eye during their actions. One of these is
called the Quadratus nictitantis, (g, fig. 139 3)
it arises from the sclerotica at the upper and
back part of the globe of the eye, and its fibres
slightly converge as they descend towards the
optic nerve, above which they terminate in a

~

AVES.

semilunar tendinous sheath, having no express
or fixed insertion. The second muscle, called
Pyramidalis nictitantis, (h, fig. 139,) arises
from the sclerotica from the lower and
nasal side of the eye-ball; its fibres con-
verge as they pass to the upper side of the
optic nerve, and there terminate in a small
round tendon, which glides through the pulley
at the free margin of the quadratus, and wind-
ing round the optic nerve, passes along a cellu-
Jar sheath at the lower part of the sclerotica,
and is inserted into the lower part of the mar-
gin of the third eye-lid, along which it is
S tinraga for some distance, and is gradually
ost.

By the simultaneous action of the two mus-
cles, the membrana nictitans is drawn forcibly
outwards and with an oblique inclination down-
wards over the anterior part of the eye.* The
tendon of the pyramidalis gains the due direc-
tion for that action by winding round the optic
nerve, and it is restrained from pressing upon
that nerve during the action of the pyramidalis
muscle by the counteracting force of the qua-
dratus, which thus augments the power of the
antagonist muscle, while it obviates any incon-
venience from pressure on the optic nerve,
which its peculiar dispositicn in relation to that
part would otherwise occasion.

To examine this singular and beautiful me-
chanism, it is necessary to remove the muscles
of the eye-ball, especially the recti.

Lachrymal Organs.—‘There are two glands
which secrete a fluid to lubricate the ball of
the eye, and facilitate the movements of the
eye-lids ; one of these relates more especially to
the movements of the nictitating membrane,
and is called from its discoverer the Harderian
Gland ; the other corresponds to the ordinary
Glandula lachrymalis.

* This oblique motion is most remarkable in the
Owls, in which the nictitating membrane is ac-
companied by the- upper eye-lid in its sweeping
movement across the eyeball:

307
The Glandula Harderiana (i, fig. 140)
is a conglomeration of mucous follicles, which
compensates for the absence of Meibomian
glands in Birds; it is generally of large size,
situated at the internal angle of the eye,
and pours out a thick viscid secretion by a
small duct which opens beneath the nictitating
membrane. The surface of the gland is di-
vided into many small lobules, which, when
injected with mercury, are seen to be com-
posed of still smaller vesicles.

It is interesting’ to find that some of the
Rodentia, which manifest so many affinities
to the Class of Birds, have a corresponding
gland; in the Hare, for example, it is of large
size and bipartite, situated at the internal angle
of the orbit, and opening beneath the internal
eye-lid.

The true lachrymal gland is situated at the
external angle of the eye. In the Goose it is
of a flattened form, about the size of a pea,
Opening upon the inside of the outer angle of
the eye-lids by a short and wide duct. Its
secretion is less viscid than that of the Har-
derian gland: but this is not uniformly the
case.

The lachrymal duct consists of a wide mem-:
branous canal commencing by two apertures at
the nasal canthus of the eye, and terminating
below and a little before the middle or great
turbinated cartilage. In the Ostrich there is
a glandular prominence at the commencement
of each of the lachrymal canals; these seem
analogous to the caruncula lachrymalis. In
other birds this structure is wanting.

Nasal gland. (k, fig. 140.)— Besides the
lachrymal glands, or those which furnish a
fluid for the purpose of lubricating, defending,
and facilitating the movements of the eye-ball,
‘there exists another gland, which, from its
position within or near the orbit, seems at first
sight to appertain to the preceding series, but
the secretion of which is exclusively emploYed
in lubricating the pituitary membrane of the
nose. This gland, which corresponds to the
nasal glands of serpents, and those described
by Jacobson* in Mammalia, is situated in
many aquatic and marsh birds above the
supra-orbital ridge in a depression noticed in
the description of the skull, (p. 278.) In
most birds it is lodged within the orbit itself;
in some it is found under the nasal bone, or
in the cavity analogous to the maxillary sinus.
In the Woodpeckers it is found in the sub-
ocular air-cell. It appears to be present in
every order of Aves.

In the Anserine Birds this gland is so situ-
ated as to complete the superior margin of the
orbit, (k’, fig. 140,) and is inclosed in an ex-
tremely dense fibrous membrane. Its duct
(1, fig. 140) is long, and ae to the nose
along an osseous groove, behind the lachrymal
bone. Its structure is simple, like that of the
salivary glands in the same class, being com-
posed of ramified follicles from which the

* Nouv. Bullet. des Sc, par la Soc. Philomath,
iii. an 6. p. 267. -
+ Nitzsch, Meckel’s Archiv. vi. p. 234.
x 2

308

acini of the cells proceed. In the Albatross
and Penguin we have traced two or three
distinct ducts leading from this gland to the
nose.

Organ of Hearing —The structure of the
organs of hearing in Birds resembles most closely
that in the higher Reptiles, especially the
Crocodile. There is no concha, or projecting

Fig. 141.

~] We,
4
LG

Organ of hearing, Oul.

auricle in this class, for collecting and con-
densing the rays of sound; but to compen-
sate for this deficiency, the labyrinth, and
especially the semicircular canals, are of large
size in proportion to the cranium. In those
Birds, however, which enjoy the locomotive
or visual faculties in a less perfect degree
than in the rest of the class, there is found
a peculiar arrangement of the feathers around
the external meatus. auditorius, which serves
in some degree the office of an external ear.
The Ostrich and Bustard (d, fig. 155) are so
provided, and these birds can raise the auditory
circle of plumes to catch distinctly any distant
sound that may alarm them. The Owls, again,
are furnished with a large crescentic mem-
brahous flap, or valve; and the membrana
tympani is situated at the bottom of a cavity
(a, fig. 141), the lining membrane of which
is disposed in folds analogous to those of the
human auricle. The opercular flap is largely
developed in our common Barn-owl (Strix
flammea). This species is also remarkable in
having the membrana tympani attached ex-
clusively to the bony meatus (b, fig. 141), and
not to the tympanic bone or os quadratum.

The bony framework of the membrana tym-
pani is sunk below the surface of the head,
and rarely projects so far from the tympanum
as to deserve the name of a meatus or canal:
it is deficient anteriorly, where it is bounded
by the tympanic bone, to which, with the ex-
ception above mentioned, the membrana tym-
pani is attached fora greater or less extent of
its anterior circumference.

The drum of the ear (c, fig. 141) is more
or less of an oval shape; it has the same
structure as in Mammals, but is extremely
delicate; it is convex externally, as in the
Reptiles, not concave, as in most Mammals.

The cavity of the tympanum is widest at its
outer part, and very irregular in the rest of its
extent. It communicates by the usual fora-

AVES.

mina with the internal ear, and is cter
with the fauces by means of the Eustachian
tube. It also communicates by three other
apertures with the cells of the bones of the
cranium. “ These,” Macartney observes, “ are
widened into something like canals, where
the holes open into them. The largest of
the foramina is in the back of the tympa-
num, and leads to the posterior cells, and
communicates above the foramen magnum
with the cellular canal of the other side. The
second opening is placed at the anterior part
of the tympanum, and conducts to the cells on
the lower and anterior part of the cranium.
The third foramen is continued amongst the
cells which surround the labyrinth. Thus
each tympanum has a communication with
the interior of all parts of the cranium, and
with each other, from which they might be
reckoned as making only one cavity. The
end of the tympanic bone, also, where it
contributes to form the parietes of the tym-
panum, has a foramen by which it derives its
supply of air. The auditory cells of the cra-
nium of birds are analogous to the mastoid of
the human subject ; but from their extent they
multiply sound much more. They are of the
greatest magnitude in the nocturnal birds of
prey; the Night-jar ( Caprimulgus ) has them
also very large: they diminish in size in other
birds, in which the posterior canals have no
direct communication with each other; they
are little observable in the Struthious Birds,
and are wanting in the Parrots, but in their
place the cavity of the tympanum is enlarged
posteriorly.”

The Eustachian tube (e, e, fig. 141) is very
large in birds; it is an osseous canal, and ter-
minates by a small aperture close to the one
of the other side, within the fissure of the
posterior nares. In the Swan the Eustachian
passages, after having reached the base of
the skull, pass forwards for about half an
inch and then unite to form one common
tube, which gradually expands until it termi-
nates just behind the posterior apertures of the
nose.

The foramina, which lead from the tym-
panum into the labyrinth, are situated within
a fossa. They do not merit the distinctions of
foramen ovale and foramen rotundum, being
both oval, and only separated by a small bony
process.

The ossicula auditis are supplied by a sin-
gle bone, analogous to the stapes, and some
cartilaginous processes representing the rudi-
ments of a malleus and incus. The ossiculum
consists of a stalk or pedicle, crowned by an
oval plate, which is applied to the foramen
that leads into the vestibule of the labyrinth.
At the other extremity it is united to two or
three cartilaginous processes, which form a tri-
angle that is attached to the membrana tym-
pani.

The elongated stapes, or tympanic ossicle, is
moved by one muscle (f, fig. 141), which
comes from the occiput and penetrating the
cavity, is affixed to the triangle that is con-
nected to the membrana tympani. This muscle,

AVES.

in consequence of the connections of the ossi-
culum, is a tensor, and draws the membrana
tympani outwards. It is counteracted by two
small tendinous cords that are extended to the
internal parietes of the tympanum.

The labyrinth of the ear of birds consists
of the vestibule, the three semicircular canals,
and the rudiment of the cochlea. These parts
are included within the bones of the cranium,
which form a dense vibratile case (d) around
the whole internal ear.

The vestibule is small in proportion to the
other parts, but is more elongated than in the
cold-blooded Reptilia.

The semicircular canals have been termed
by Scarpa, from their gradation in bulk,
canales major, minor, and minimus. The
largest is most superior, and has a vertical
position* (h, fig. 141). The smallest is situ-
ated horizontally (k,k). The canalis minor
or second canal (2) is vertical, it ascends upon
the horizontal canal, and opens into its side
at m. They contain corresponding tubes of
vascular membrane, and they also possess en-
larged ampulle (/), on which the nerves are
distributed in the same manner as in mam-
malia.

The place of the cochlea is supplied bya
short obtuse osseous conical tube (n, fig. 141),
as in the Crocodile, very slightly bent, with
the concavity directed backwards. Its interior
is occupied by two small cylinders of fine car-
tilage, each a little twisted, and united by a thin
membrane at their origin and termination. They
proceed from the osseous bar, which separates
the two foramina, corresponding to the foramen
ovale and rotundum. The sulcus, which is left
between the cartilages, is dilated near the point,
and accommodates the same branch of the
auditory nerve, which is sent to the cochlea in
mammalia. This nerve spreads in fine fila-
ments upon the united extremity of the carti-
laginous cylinders. The tube is divided by
the presence of the cartilages into two scala,
the anterior of which communicates with the
vestibule and is not closed; the posterior scala
is shorter, and communicates with the tym-
panum by the foramen rotundum, which is
closed by a membrane. Besides these parts the
cochlea still contains a trace of the cretaceous
substance which forms so conspicuous a part
of the organization of the internal ear in
Fishes.

The Struthious birds manifest their close
relation to the pepe by having the tube
corresponding to the cochlea, very small in
proportion to the other parts.

e seventh cerebral nerve is received into
a fossa, and there divides into five branches ;
one is the facial, or portio dura, and the others
are sent to the semicircular canals and the tube.
The facial nerve receives a filament from the
par vagum, which traverses the ear, and is
afterwards distributed to the palate.

Comparetti has described two canals leading

* In the Insessores this canal is generally the
smallest of the three.

309

from the labyrinth of birds, which correspond
with the aqueducts of the mammalia.*

Organ of Smell.—The close affinity subsist-
ing between the cold and warm-blooded ovipara
is no where more strongly manifested than in
the olfactory organs. The external nostrils are
simple perforations, having no moveable car-
tilages or muscles provided for dilating or con-
tracting their apertures, as in mammalia. The
extent of surface of the pituitary membrane
is not increased by any large accessory cavities,
but simply by the projections and folds of the
turbinated bones. The olfactory nerve is sim-
ple, as in the Tortoise, and passes out of
the skull, as before observed, by a single fo-
ramen.

The external nostrils vary remarkably both
in shape and position, and serve on that ac-
count as zoological characters. They are placed
at the sides of the upper mandible in the
majority of birds, but in some species are
situated at or above the base of the bill; the
latter is the case in the Toucans; in the Ap-
teryx Australis they are found at the extremity
of the long upper mandible.

In general they are wide and freely open to
facilitate the inhalation of air during the rapid
motions of the bird, but sometimes they are
so narrow that, as in the Herons, they will
scarcely admit the point of a pin; and in the
Gannet they have been supposed, but erro-
neously, to be wanting altogether,+ ,

In the Rasores the nostrils are partially
defended by a scale. In the Corvide they
are protected by a bunch of stiff feathers
directed forwards. In the Petrels the nostrils
are produced in a tubular form, parallel to one
another for a short distance along the upper
part of the mandible, with the orifices turned
forwards (a, fig. 142.)

The septum narium is, in general, complete,
and is partly osseous, partly cartilaginous. It
is perforated in the Swan just opposite the
external nostrils. The surface of the septum
is very irregular in this bird, and the pituitary
membrane which covers it is highly vascular.

The outer side of each of the nasal passages
gives attachment to three turbinated lamine.
The inferior one is a simple fold adhering to
the septum narium as well as to the side of the
nose; the middle one is cartilaginous and is
the largest. It is of an infundibular figure,
and adheres by its base to the septum of the
nose, and externally to the cartilaginous ala or
side of the nostril. It is convoluted with two
turns and a half in the Anserine Birds, but
in the Grallatores it is compressed and forms
only one turn anda half. The superior tur-
binated lamina (m m, fig. 140) generally
presents the form of a bell; it is also cartila-
ginous, and adheres to the ethmoidal and
lachrymal bones. It is hollow, and divided
into two compartments, which are prolonged
in a tubular form; the internal one extends to

* See Cuvier, Legons d’Anat. Comp. tom. ii.,
and Macartney in Rees’ Cyclopedia, Art. Birds.
+t See Montague’s Ornithological Dictionary.

310

the orbit, the external terminates behind the
middle turbinated lamina in a cul-de-sac.
These olfactory lamine differ in regard to tex-
ture. In the Cassowary and Albatross they
are said to be membranous. ‘Cuvier states that
they ig eee to him to be bony in the Horn-
bill and Toucan. We have found this to be the
case in the recent Toucan. The organ of smell in
this singular species is confined to the base of its
enormous beak, (d, e, fig. 150.) The canal, which
is traversed by the air and odorous particles in
inspiration, forms a sigmoid curve in the vertical
direction. The external orifice is on precisely
the same perpendicular line as the internal,
Or, as it is generally termed, the posterior nasal
aperture. The external nostril (d, fig. 150)
being situated on the posterior surface of the
upper mandible, where it is raised above the
Jevel of the cranium, is consequently directed
backwards, secure from all injury to which it
might be exposed while the bill was used in
penetrating dense and interwoven foliage.
The olfactory canal is at its commencement
of a cylindrical form, and about two lines in
diameter. It passes forwards for about half an
inch, receiving the projection of the first spongy
bone, then bends downwards and backwards,
and is dilated to admit the projections of the
two other spongy bones. From this point it
descends vertically to the palate, at first con-
tracted and afterwards dilating to form the in-
ternal or posterior orifice, (e, fig. 150.) The
first or outermost spongy bone is almost hori-
zontal, and has its convexity directed outwards.
The second is nearly vertically placed, with its
convexity directed backwards: it terminates in
a narrow point below. The superior spongy
bone is about the size and shape of a pea.
All these bones are processes from the inner
and posterior parietes of the nasal passage ;
they are cellular, and air is continued into
them from the cranial diploé ; but the parietes
of the nasal passage are entire and smooth,
and lined by a delicate pituitary membrane, so
that there is no direct communication between
the cells, the turbinated bones, or of the man-
dible and the nasal passages.

In most birds the nasal cavities communicate
with the pharynx by two distinct but closely
approximated apertures. In the Cormorant,
however, these join into one before their termi-
nation posteriorly, which is consequently by a
single aperture. ‘The olfactory nerves are dis-
tributed exclusively to the pituitary membrane
covering the septum narium and the superior
spongy bone. The pituitary membrane is of
the most delicate structure, and is most vas-
cular, where it covers the superior turbinated
Jamina, and becomes thicker and more villous
-as it descends upon the middle one. It every-
where displays numerous pores of muciparous
glands, which bedew it with a lubricating
secretion.

According to Scarpa the acuteness of smell
is exactly in proportion to the development of
the superior turbinated lamina, to which the
size of the olfactory nerve corresponds. The
following is the order in which, according to

AVES.

his experiments, birds enjoy the sense of smell,
beginning with those in which it is most acute:
Grallatores, Natatores, Raptores, Scansores,
Insessores, Rasores. . .

There is still, however, much obscurity
with reference to the extent to which Birds
make use of their olfactory organs. It has
been generally asserted that birds of prey are
gifted with a highly acute sense of smell, and
that they can discover by means of it the
carcass of a dead animal at great distances ;
but those who have witnessed the rapidity with
which the Vu'tures descend from invisible
heights of the atmosphere to the carcass of an
animal, too recently killed to attract them by
Rianne exhalations, have generally been
ed to consider them as being directed to their
quarry by sight. “ That this is the case,” Dr.
Roget observes, “appears to be now suffi-
ciently established by the observations and
experiments of Mr. Audubon, which show that
these birds in reality possess the sense of smell
in a degree very inferior to carnivorous quadru-
peds, and that so far from guiding them to
their prey from any distance, it affords them no
indication of its presence even when close athand.
The following experiments appear to be perfect-
ly conclusive on this subject. Having pro-
cured the skin of a deer, Mr. Audubon stuffed
it full of hay; after the whole had become
perfectly dry and hard, he placed it in the mid-
dle of an open field, laying it down on its back
in the attitude of a dead animal. In the
course of a few minutes afterwards he observed
a vulture flying towards and alighting near it.
Quite unsuspicious of the deception, the bird
immediately proceeded to attack it as usual in
the most vulnerable points. Failing in this
object, he next with much exertion tore open
the seams of the skin where it had been stitched
together, and appeared earnestly intent on get-
ting at the flesh, which he expected to find
within, and of the absence of which not one
of his senses was able to inform him. Find-
ing that his efforts, which were long reiterated,
led to no other result than the pulling out large
quantities of hay, he at length, though with
evident reluctance, gave up the attempt, and
took flight in pursuit of other game to which
he was led by the sight alone, and which he
was not long in discovering and securing.

“‘ Another experiment, the converse of the
first, was next tried. <A large dead hog was
concealed in a narrow and winding ravine,
about twenty feet deeper than the surface of
the earth around it, and filled with briers and
high cane. This was done in the month of
July, in a tropical climate, where putrefaction
takes place with great rapidity; yet, although
many vultures were seen from time to time
sailing in all directions over the spot where the
putrid carcass was lying, covered only with
twigs of cane, none ever discovered it; but in
the meanwhile several dogs had found their

way to it and had devoured large quantities of —

the flesh.”*

* See Roget, Bridgewater Treatise, vol. ii. p. 406

AVES.

Organ of Tuste—The gustatory sense is very
imperfectly enjoyed in birds, which, having no
manducatory organs, swallow the food almost
as soon as seized. The tongue is organized
chiefly to serve as a prehensile instrument, and
its principal modifications will be treated of
under the head of the Digestive Organs. It is
generally sheathed at the anterior part with
horn (h, fig. 152), and is destitute of papille
except at its base (0, fig. 152) near the aper-
ture of the larynx; these papille are not, how-
ever, supplied by a true gustatory nerve, but by
filaments of the glossopharyngeal. No branch
of the fifth pair goes to the tongue.

The tongue is proportionally largest and
most fleshy in the Parrot tribe, and the food
is detained in the mouth longer in these than
in other birds. It is triturated and commi-
nuted by the mandibles certainly, and turned
about by the tongue, which here seems to ex-
ercise a gustatory faculty, since indigestible
pt as the coat of kernels, &c. are rejected.

n the Lories the extremity of the tongue is
provided with numerous long and delicate pa-
pill or filaments projecting forwards.

Organs of Touch.—W ith respect to the tactile
instruments, but few observations can be made
in the class of Birds. The anterior extremities
have their digital extremities undivided and
entirely unfitted for the exercise of this sense,
and the posterior extremities are but little better
organized for the purpose. The integument
covering the toes is very sparingly supplied
with nerves, and is of a texture scarcely fitted
for ascertaining the superficial qualities of
bodies. However, the villion the under sur-
face of the toes are observed to be remarkably
long in the Capercailzie ( Tetrao urogallus),
but this is probably for the purpose of enabling
them to grasp with more security the frosted
branches of the Norwegian pine-trees. The
Parrots seem to use their feet more like instru-
ments of touch, but in them the action may
be merely prehensile.

The only organ of touch respecting which
_ there can be no doubt is the bill. Even where
this is covered with a hard sheath of horn, some
filaments of the fifth pair (c, fig. 150) may be
traced terminating in small papille ; but in the
Lamelli-rostral water-birds the bill is covered
by a softer substance, and is plentifully supplied
by branches of the fifth pair of nerves. (See
Nerves.) In the Woodcocks and Snipes the
long bill is so organized that it is used as a
probe in marshes and soft ground to feel for
row small worms and slugs that constitute their

The cire in the Falconide, the wattles of
the Wattle-birds (Philedon carunculatus and
Glaucopis cinerea) and of the Cock, the ca-
runcles of the King-Vulture and Turkey, may
also be regarded in some degree as organs of
touch.

Organs of Digestion —The digestive function
in birds is necessarily extremely powerful and
rapid in order to supply the waste occasioned
by their extensive, frequent, and energetic mo-
tions, and in accordance with the rapidity of

3il

their circulation and their high state of irrita-
bility. *

The parts to be considered with reference to
this function are the rostrum or beak, the
tongue, the cesophagus, the stomach which is
always divided into a glandular and muscular
portion, the intestines, and the cloaca.

The glandular organs of the digestive system
are the salivary glands, the proventricular fol-
licles, the liver, pancreas, and spleen.

The beak consists of the maxillary and inter-
maxillary bones, which in place of teeth are
provided with a sheath of horny fibrous mate-
rial, exactly similar to that of which the claws
are composed: this sheath is moulded to the
shape of the osseous mandibles, being formed by
a softvascular substance covering these parts, and
its margins are frequently previded with horny
processes or laminz secreted by distinct pulps,
and analogous in this respect to the whalebone
lamine of the Whale: M. Geoffroy St. Hilaire
has described a structure in the bill of birds
which presents a closer approach toa dentary
system. Ina foetus ofa Perroquet nearly ready
for hatching, he found that the margins of the
bill were beset with tubercles arranged in a re-
gular order and having all the exterior appear-
ances of teeth: these tubercles were not, indeed,
implanted in the jaw-bones, but formed part
and parcel of the exterior sheath of the bill.
Under each tubercle, however, there was a ge-
latinous pulp, analogous to the pulps which
secrete teeth, but resting on the edge of the
maxillary bones, and every pulp was supplied
by vessels and nerves traversing a canal in the
substance of the bone. These tubercles form
the first margins of the mandibles, and their
remains are indicated by canals in the horny
sheath subsequently formed, which contain a
softer material, and which commence from
small foramina in the margin of the bone.

The different degrees of hardness and varieties
of form.of the beak exercise, Cuvier observes,
as much influence upon the nature of birds as
the number and figure of the teeth do upon
that of Mammals.

The beak is hardest in those birds which
tear their prey, as in Eagles and Falcons; or
in those which bruise hard seeds and fruits, as
Parrots and Gros-beaks; or in those which pierce
the bark of trees, as Woodpeckers, in the larger
species of which the beak absolutely acquires
the density of ivory.

The hardness of the covering of the beak
gradually diminishes in those birds which take
less solid nourishment, or which swallow their
food entire; and it changes at last to a soft skin
in those which feed on tender substances, or
which have occasion to probe for their food in
muddy or sandy soils, or at the bottom of the
water, as Ducks, Snipes, Woodcocks, &c.

Cateris paribus, a short beak must he stronger
than a long one, a thick one than a thin one, a
solid one than one which is flexible ; but the

* The Cormorant readily devours six or eight
pounds of fish daily. y
+ Anatomie Comparée, tom. ii. p. 192.

general form produces infinite variety in the
application of the force.

A compressed beak with sharp edges and a
hooked extremity characterizes both the Birds
of Prey properly so called, which destroy the
smaller iabrnpeds and birds (fig. 112); and
also the carnivorous species of a different order
that live on fish, as the Petrels (fig. 142), Al-

Fig. 142.

Z oe: ——-
Cs =A

Bill of the Petrel.

batrosses, Frigate-bird, and Tropic-bird. But
in the Raptores it is comparatively shorter and
stronger, and in some genera a tooth-like pro-
cess on either side adds considerably to its
destructive powers: hence the Falcons which
possess this armature are reckoned the more
‘noble’ and courageous Birds of Prey.

The Insessorial Shrikes which have their bill
similarly armed do not yield in courage to the
Hawks, notwithstanding their small size, and
the comparative feebleness of their wings and
feet: (fig. 115.)

As the bill becomes narrower and straighter,
it characterizes birds of a voracious habit, but
less daring in their attacks on other birds,
such as the Crows, Magpies, &c., (fig. 116) ;
and the compressed knife-shaped bill is asso-
ciated with similar habits in the Water-birds,
as the Gulls, Grebes, Dabchicks, &c.

Another kind of strong

of being as deep as it is long), and the Skimmer
(Rhyncops ), in which the still more singular
structure obtains of an inequality in the length
of the two mandibles, the upper one being con-
siderably the shortest; so that this bird can
only get its food, which consists of floating
marine animals, by pushing them before it
as it skims along the surface of the water.

(a Fig. 144.
f=
—— J

Bill‘of the Skimmer.

Lastly, there are trenchant bills which
are depressed or flattened horizontally; they
serve to seize fishes and reptiles, and other
large objects; the Boat-bill ( Cancroma )
exhibits a bill of this kind ‘( fig. 145), which
is also ser- Fig. 145.

catcher and
Tody have

Of the blunt-edged bills we may first notice
those which are flattened horizontally. When

rated at the

Cems
this form of
a bill of this description is long and strong, as

edges. Some
speciesof F'ly-

beak on a Mite
in the Pelecan (fig. 146), it serves to seize a
large but feebly resisting prey, as fishes.

Fig. 146.

and trenchant bill, which

is more elongated and
without a hook, serves to
cut and break, but not

to tear: this form of bill
characterizes the Waders
which frequent the water
and prey upon animals
that make resistance in
that element, as reptiles,
fishes, &c. In the He-
rons and Bitterns the.
bill is straight; in the Ib's it is curved down-

wards ( fig. 123); in the Jabiru (fig. 143) it
is curved in the contrary direction.

Fig. 143.

Bul of the Jabiru.

Some trenchant or sharp-edged bills are
so compressed as to resemble the blade of
a knife, and can only serve to seize small ob-
jects, which are immediately swallowed : such
is the form of the beak in the Auks, Puffins,
Coulterneb, (where it has the further peculiarity

Bill of the Pelecan.
When it is long and weak, as in the Spoon-
bill, which derives its name from the dilated
extremity of the mandibles, it is only available

to seize amid sand, mud, or water, very small
Crustaceans, Mollusks, &c. (fig. 147.)

Fig. 147.

ee
Bill of the Spoonbill.
The more or less flattened bills of Ducks, the

more conical ones of Geese and Swans, and
that of the Flamingo,* of which the extremities

* It is singular that it should ever have been
sgpponed that the upper mandible was alone move-
able, and the lower mandible perfectly immoveable,
in the Flamingo, since precisely the contrary is the

OO Oe ee ee eee

AVES, 313

of the mandibles are bent downwards abruptly
(fig. 148), have all transverse horny lamine

Bill of the Flamingo.

arranged along their edges, which, when the
bird has seized any object in the water, serve,
like the whalebone laminz of the Whale, to give

assage to the superfluous fluid. The aquatic
habits of all these birds are in harmony with
this structure. In the Goosanders ( Mergus ),

Fig.

which are nearly allied to the Anatide, the la-
teral laminze are developed into small conical
tooth-like processes, which serve to hold fast
the fishes, which the Goosander destroys in
great numbers.

Fig. 149.

ZK Renna AMAA ANAARHA <<

—
Bill of the Goosander.

The bills of the Toucans and Hornbills are
remarkable for their enormous size, which is
sometimes equal to that of the whole bird.
The substance of the beak in these cases is
extremely light and delicately cellular, without
which the equilibrium necessary for flight
would have been destroyed. The singularity
of the structure of these bills demands a more
particular consideration.

The osseous portions of the mandibles of
the Toucan (fig. 150) are adapted to com-

150.

Bill of the Toucan.

bine, with great bulk, a due degree of

strength and remarkable lightness, and their
structure is consequently of a most beautiful
and delicate kind. The external parietes are
extremely thin, especially in the upper beak :
they are elastic, and yield in a slight degree to
moderate pressure, but present considerable
resistance if the force be increased for the pur-
pose of crushing the beak. At the points of
the mandibles the outer walls are nearly a line
in thickness; at other parts in the upper beak

case. In the specimen which we dissected (see
Proceedings of the Zoological Society, Part ii.
p- 141) the upper mandible was so firmly fixed to
the craninm as only to be moved with that part,
while the lower mandible was freely moveable
when the head was fixed, The Flamingo is remark-
able for applying the upper mandible to the soil,
are it shovels backwards in searching for its
ood.

they are much thinner, varying from one-
thirtieth to one-fiftieth part of an inch, and in
the lower beak are from one-twentieth to one-
thirtieth of an inch in thickness.

On making a longitudinal section of the upper
mandible (a, fig.150) in the Rhamphastos Touco,
its base is seen to include a conical cavity about
two inches in length and one inch in diameter,
with the apex directed forwards. The walls of
this cone consist of a most beautiful osseous
net-work, intercepting irregular angular spaces,
varying in diameter from half a line to two
lines. From the parietes of the cone a net-
work of bony fibres is continued to the outer
parietes of the mandible, the fibres which imme-
diately support the latter being almost invariably
at right angles to the part in which they are in-
serted. The whole of the mandible anterior to
the cone is occupied with a similar net-work, the
meshes of which are largest in the centre of

314

the beak, in consequence of the union which
takes place between different small fibres as
they pass from the circumference inwards. It
is worthy of observation that the principle of
the cylinder is introduced into this elaborate
structure: the smallest of the supporting pillars
of the mandibles are seen to be hollow or
tubular when examined with the microscope.
The structure is the same in the lower man-
dible (m, fig. 150), but the fibres composing
the net-work are in general stronger than those
of the upper mandible.

The medullary membrane lining these cavi-
ties appears to have but a small degree of
vascularity. Processes of the membrane, ac-
companying vessels and nerves, decussate the
conical cavity at the base of the beak. The air is
admitted to the interior of the upper mandible
from a cavity (6, fig. 150) situated anterior to
the orbit, which communicates at its posterior
part with the air-cell continued into the orbit,
and at its anterior part with the maxillary
cavity. The nasal cavity is closed at every
part except at its external and internal aper-
tures by the pituitary membrane, and has
no communication with the interior of the
mandible. *

The horny sheath of the mandibles in the
Hornbills and Toucans is so thin that it often
becomes irregularly notched at the edge from
use. The Hornbills have, besides, upon their
enormous beak, horn-like prominences of the
same structure and of different forms, the use
of which is not known.

The Trogons, Touracos, Buccos, &c. exhibit
forms of the bill which are intermediate to that
of the large but feeble bill of the Toucans, and
the short, but hard, strong, and broad bill of
the Parrot-tribe, which is also hooked, so as
to assist in climbing, like a third foot: (fig.
128.)

The short, conical, and vaulted beak of the
Rasores ( fig. 121) serves to pick up with due
rapidity the vegetable seeds and grains which
constitute their food, as well as small insects,
as ants, &c. with which the young are frequently
nourished.

The bills of the small Insessorial or Pas-
serine birds present every gradation of the
conical form, from the broad-based cone of the
Hawfinch to the almost filamentous cone of the
Humming-birds (fig. 117, 125), and each of
these forms influences the habits of the species
in the same manner as in the larger birds. The
short and strong-billed Insessores live on seeds
and grains; those with a long and slender bill
on insects or vegetable juices. If the slender
bill be short, flat, and the gape very wide, as
in Swallows, the bird takes the insects while
on the wing (fig. 118) ; if the bill be elongated
and endowed with sufficient strength, as in the
Hoopoes, it serves to penetrate the soil and

ick out worms, &c.

Of ail bills, the most extraordinary is that of
the Cross-bill, in which the extremities of the
mandibles curve towards opposite sides and

* See Anatomical Appendix to Gould’s Mono-
graph on the Ramphastide, fol.

AVES.

cross each other at a considerable angle—a dis-
position which at first sight seems directly
opposed to the natural intention of a bill.
With this singular disposition, the Cross-bill,
however, possesses the power of bringing the
points of the mandibles into contact with each
other ; and Mr. Yarrell, in his excellent pee
on the Anatomy of the Beak of this bird, ob-
serves that, notwithstanding M. Buffon’s asser-
tion to the contrary, it can pick up the smallest
seeds, and shell or husk hemp and similar
seeds like other birds. He further shows that
the disposition and power of the muscles is such
that the bill gains by its very apparent defect
the requisite power for breaking up the pine-
cones that constitute its natural food. In a
pair of Cross-bills which were kept for some
time in captivity, one of their principal occu-
pations, Mr. Yarrell observes, “ was twisting
out the ends of the wires of their prison, which
they accomplished with equalease and dexterity.
A short flat-headed nail that confined some
strong net-work was a favourite object upon
which they tried their strength, and the male,
who was usually pioneer in every new exploit,
succeeded, by long-continued efforts, in draw-
ing this nail out of the wood, though not
without breaking off the point of his beak in
the experiment. Their unceasing destruction
of cages at length brought upon them sentence
of banishment.” Te concludes his memoir by
observing that “ the remarks of Buffon on the
beak of this bird, which he characterizes as
‘an error and defect of nature, and a useless
deformity,’ exhibit, to say the least of them,
an erroneous and hasty conclusion, unworthy
of the spirit of the science he cultivated.
During a series of observations on the habits
and structure of British Birds, 1 have never
met with a more interesting or beautiful ex-
ample of the adaptation of means to an end
than is to be found in the tongue, the beak,
and its muscles, in the Cross-bill.” *

The tongue, as has been already observed,
can hardly be considered as an organ of taste
in Birds, since, like the mandibles, it is gene-
rally sheathed with horn. It is principally
adapted to fulfil the offices of a prehensile
organ in association with the beak, and it pre-
sents almost as many varieties of form. Orni-
thologists have not yet perhaps derived all the
advantages which a study of the modifications
of the tongue might afford in determining the
natural affinities of birds.

The os hyoides very much resembles that of
Reptiles. Its parts have been minutely studied
by Geoffroy St. Hilaire, who has bestowed
upon them separate names: (a, fig. 151) is the
glosso-hyal, b the basi-hyal, dd the apo-hyals,
e e the cerato-hyals, ¢ the uro-hyal. The
body, or basi-hyal element, is more thickened
than the rest: in some birds it is cylindrical.
The length of the tongue depends chiefly on that
of the lingual process or glosso-hyal element.
In most birds it is lengthened out by a carti-
lage a‘ appended to its extremity. This is re-
markable in the Swan and other Lamelli-rostres.

* Zool. Journal, vol. iv. p. 464.

ee EEE

L
;
|
,
i
j

oS ae a ee

In the Humming-bird, and especially in

the Toucan and Woodpecker, the horny sheath
of the glosso-hyal presents singular pecu-
liarities. In the Humming-bird it is divided
at its extremity into a pencil of fine hairs,
well fitted for imbibing the nectar and farina
of flowers. In the Toucan’s tongue (fig. 152)
the sheath gives off from the lateral margins
stiff bristle-like processes which project for-
wards ; this structure is continued to the apex,

315

A %

Os hyoides and larynx 2
Swan.

and the tongue so provided becomes an in-
strument for testing the softness and ripe-
ness of fruit, and the fitness of other objects
for food, thereby acting as a kind of antenna
or feeler. A similar but less developed struc-
ture is found in the tongue of the frugivorous
Touraco.

In the Woodpeckers the apex of the
horny sheath (a, fig. 153, 154) gives off at, the
sides short-pointed processes directed back-
wards, which thus convert it into a barbed
instrument, fitted for holding fast the insects
which its sharp point has transfixed, after the
strong beak has dislodged them from their
hiding places. The cornua of the os hyoides
in the Woodpecker extend backwards to the
vertebral column, wind round the back of the
head, and converge as they pass forwards to be
inserted in a canal generally on the right side of
the upper mandible (d, e, fig. 153, 154.)

Fig. 153.

re et
Cranium and tongue of a Woodpecker.

One of the most remarkable structures which
the tongue presents in this class is met with in
the Flamingo, where it is remarkable both for its
size, texture, and singulararmature. The tongue
is almost cylindrical, slightly flattened above,
and obliquely truncate anteriorly, so as to cor-
respond with the form of the inferior mandible.
The pointed extremity of the truncated part is
supported beneath by a small horny plate.
Along the middle of the upper surface there is
a moderately deep and wide longitudinal
furrow; on either side of which there are
from twenty to twenty-five recurved spines,
from one to three lines in length. ese
spines are arranged in an irregular alternate
series : the outer ones being the smallest, which

SSS
Tongue of the Toucan.

may almost be considered as a distinct row.
At the posterior part of the tongue there are
two groups of smaller recumbent spines di-
rected towards the glottis. The substance of
the tongue is not muscular, but is chiefly
composed of an abundant elastic cellular sub-
stance, permeated by an oily fat.

In the Raptores the tongue is of a mode-
rate length,—broad, and somewhat thick, and
has a slight division at the tip. In the Vultures
its sides can be voluntarily approximated so
as to form a canal, and its margins are pro-
vided with retroverted spines. In the Raven
it is bifid at the apex.

In the Struthious birds, in many of the
Waders, and in the Pelecanida, the tongue is
remarkably short.

In the Parrots it is thick and fleshy, serves
admirably to keep steady the nut or seed upon
which the strength of the mandibles is exerted,
and is applied to the kernel so extracted, as if
to ascertain its sapid qualities.

The following are the muscles of the tongue
in birds.

Ist. The Genio-hyoideus of Vicq d’Azyr,
or the Mylo-hyoideus according to Cuvier.
This is a thin layer of fibres attached to the
lower and inner border of the lower jaw, and
running transversely to a mesial tendon which
separates them, and extends to the uro-hyal.
It raises the tongue towards the palate.

2d. The Stylo-hyoideus arises from the upper
and back part of the lower jaw, and divides into
three or more portions: the posterior descends
obliquely forwards, and is inserted into the
tendinous commissure of the preceding mus-
cle; the middle portion is inserted into the
‘ uro-hyal :’ the anterior fasciculus is inserted
into the side of the basi-hyal above the trans-
verse hyo-glossus. The actions of these dif-
ferent portions vary according to their insertion ;
the first and second depress the apex of the
tongue by raising its posterior appendage,
(uro-hyal,) the third raises the tongue and
os hyoides, and draws it to one side when it
acts singly. -

3d. The Genio-hyoideus arises by two fleshy

316 AVES.

bands from the lower and internal edge of the
lower jaw; these unite and surround the cerato-
hyals or cornua of the os hyoides ; and as they
draw forward the os hyoides, protrude the
tongue from the beak.

4th. The Cerato-hyoideus passes from the
cerato-hyal to the uro-hyal, and is therefore
subservient to the lateral movements of the
tongue.

5th. The Sterno-hyoidei are replaced by a
slip of muscle which extends from the anterior
surface of the upper larynx to be attached to
the base of the glosso-hyal.

6th. A small and short muscle is single or
azygos ; it passes from the basi-hyal to the
under part of the glosso-hyal; it depresses the
tip of the tongue and elevates its base.

7th. A short muscle which arises from the |

junction of the basi-hyal with the cerato- and
uro-hyals, and is inserted into the upper and
outer angle of the base of the glosso-hyal.

All these muscles are remarkably large in
the Woodpecker, in which there is a singular
pair of muscles that may be termed Cerato-
tracheales, (h, fig. 154.) They arise from the
trachea about eight lines from the upper larynx,
twist four,times spirally round the trachea, and
then pass forward to be inserted into the base
of the cerato-hyals. This is the principal re-
tractor of the singular tongue in this species.

Salivary glands.—The salivary organs, being
in general developed in a degree corresponding
to the extent of the changes which the food
undergoes in the mouth, and the length of
time during which it is there detained, are by
no means so conspicuous a part of the diges-
tive system in Birds as in Mammals. Glands
which pour out their secretion upon the food
prior to deglutition are, however, met with in
every bird, but vary in number, position, and
complexity of structure.

In some species, as the Crow, they are of
the simplest structure, consisting of a series
of unbranched, cone-shaped follicles or tubules,
Opening separately upon the mucous mem-
brane of the mouth, along the sides of which
cavity they are situated. They pour out a
viscid mucus, and are the only traces of a
salivary system met with in this bird.

In many other birds, and especially in the
Scratching, Wading, and Swimming Orders,
glands of the conglomerate structure are found
beneath the lower jaw, analogous to the sub-
maxillary glands of quadrupeds.

In the Goose they occupy the whole of the
anterior part of the space included by the rami
of the lower jaw, being of an elongated form,
flattened and closely united together at the
middle line. On either side of this line the mu-
cous membrane of the mouth presents inter-
nally a series of pores, each of which is the
terminal orifice of a distinct gland or aggre-
gate of ramified ducts.

A third and higher form of salivary gland,
in which the secretion of the conglomerate
mass is conveyed into the mouth by a single
duct, is found in the Woodpeckers and some
species of the Rapacious Order. In the latter
birds these glands are termed, from their situ-

Fig. 154. ad |

Tongue and salivary glands, Woodpecker.
ation, anterior palatine: in the Pice they
correspond to the parotid and sublingual of
Quadrupeds.

The sublingual glands of the Woodpecker
are of extraordinary size, extending from the
angle to the symphysis of the lower jaw. The
single ducts of each gland unite just before
their termination, which is a simple orifice at
the apex of the mouth. The structure of these
glands is shown at i, k, fig. 154.

Besides the preceding, which may be con-
sidered as the true salivary glands, there are
numerous accessory follicles in ce
of the oral apparatus of birds. In the Water-
hen ( Gallinula chloropus) there is a series of
cecal glandular tubes along each side of the
tongue ; and it is interesting to note that glan-

—— ee dine oue’

AVES.

dular follicles are found abundantly developed
on the tongues of the Chelonian and Saurian
reptiles. Similar elongated follicles are situated
along the margin of the lower jaw, resembling
in their parallel pectinated disposition the bran-
chiz of Fishes. In the Goose the corresponding
follicles are longer and wider, and are situated
near the sides of the tongue. In the Raven these
mucous follicles are narrower but longer.

The food, after being embued with the secre-
tion of the preceding glands, is poised upon
the tongue and swallowed partly by means
of the pressure of the tongue against the palate,

artly by a sudden upward jerk of the head.

he posterior apertures of the nostrils being
generally in the form of narrow fissures are
undefended by a soft palate or uvula ; and the
laryngeal aperture, which is of a similar form,
is in like manner unprovided with an epi-
glottis, but is defended by the retroverted
oe at the base of the tongue. In many

irds, indeed, as the Albatross and Coot, there
is a small cartilage in the usual place of an
epiglottis, but insufficient to cover more than
avery small part of the laryngeal aperture.
Nitzsch has devoted a treatise to these rudimen-
tary epiglottides in Birds.*

With respect to the fauces the remarkable
instance of a dilatation of these parts in the
Pelecan must not be forgotten. The exten-
sibility of the membrane between the rami of
the lower jaw admits of its formation into a
bag (a, fig. 146), which is calculated to contain
ten quarts of water, and serves as a receptacle for
fishes, making in that state a conspicuous appen-
dage to the huge bill; when empty it can be
contracted so as to be hardly visible. By means
of this mechanism a quantity of food can be
transported to the young ; and, as in disgorging
the bleeding fishes the parent presses the
bottom of the sac against her breast, this
action has probably given rise to the fable
of her wounding herself to nourish the young
with her own blood.

A remarkable provision of an analogous na-
ture is met with in the Bustard as a sexual pecu-
liarity(fig.155). In Fig. 155.
the male there is a ATA
membranous sac
extending for some
way down the an-
terior part of the
neck capable of
holding several
quarts of water ;
it communicates
with the mouth by
an aperture be-
neath the tongue.
It is not found ex-
cept in the mature
bird. It is su
posed to serve the
purpose of provid-
ing the female and
young during the
breeding season

\\ Pe UT :
ps
y wats

Faucial bag of the Bustard.
* See Meckel’s Archiven, 1826, p. 613.

817

with water, and hence may not be developed to
its full extent except at that period.

The Swift presents an analogous dilatation of
the membrane of the fauces at the base of the
lower jaw and upper part of the throat: it is
most developed at the period of rearing the
young, when it is generally found distended
with insects in the old birds that are shot while
on the wing. This receptacle is of a rounded
form, and communicates with the fauces by
a wider opening than that of the Bustard ; it is
also proportionally of less extent. A similar
structure obtains in the Rook and probably in
other Insectivorous birds.

The csophagus (H, fig. 171: a, fig. 156,
158), like the neck, is usually very long in birds :
as it passes down, it generally inclines towards
the right side; it is partially covered by the tra-
chea (G, fig. 171), and connected to the sur-
rounding parts by a loose cellular tissue. It is
wide and dilatable, corresponding to the im-
perfection of the oral instruments as comminu-
tors of the food. Inthe rapacious and especially
in the piscivorous birds it is of great capacity,
enabling the latter to swallow the fishes entire,
and serving also in many Waders and Swim-
mers as a temporary repository of food.

When the Cormorant has by accident swal-
lowed a large fish, which sticks in the gullet,
it has the power of inflating that part to its
utmost, Pe while in that state the head and
neck are shaken violently, in order to promote
its passage. In the Gannet the cesophagus is ex-
tremely capacious, and, as the skin which covers
it is equally dilatable, five or six herrings may be
contained therein. In both these species it
forms one continued canal with the stomach.

In the Flamingo, on the contrary, the dia-
meter of the gullet does not exceed halfan inch,
being suited to the smallness of the objects
which constitute the food of this species.

Besides deglutition the cesophagus is fre-
quently concerned in regurgitation; and in
the Birds in which this phenomenon occurs,
the muscular coat of the gullet is well deve-
loped, as in the Ruminant Mammalia. The
Raptores, for example, habitually regurgi-
tate the bones, feathers, and other indiges-
tible parts of their prey, which, in the lan-
guage of the falconer, are called ‘ castings.’
A Toucan, which was preserved some years
alive in this country, was frequently observed
to regurgitate partially digested food, and after
submitting it to a rude kind of mastication by
its enormous beak, again to swallow it.

The cesophagus possesses an external cel-
lular covering, a muscular coat, an internal
vascular tunic, and a cuticular lining. The
muscular coat consists of two layers of
fibres ; in the external stratum they are trans-
verse (a, fig. 159), in the internal longitudinal
(b, fig. 159); the reverse of the arrangement
observed in the human subject.

Ingluvies—In those birds which are om-
nivorous, as the Toucans and Horn-bills, in
the frugivorous and insectivorous birds, and in
most of the Grallatores, which find their food
in tolerable abundance, and take it in small
quantities without any considerable _inter-

318

mission, it passes at once to the stomach to be
there successively digested, and the gullet pre-
sents no partial dilatations to serve as a tem-
porary reservoir or macerating receptacle. But
in the larger Raptorial Birds, as the Eagles
and Vultures, which gorge themselves at un-
certain intervals from the carcasses of bulky
prey, the esophagus does not preserve a uni-
form width, but undergoes a lateral dilatation
anterior to the furculum at the lower part of
the neck. This pouch is termed the ingluvies

or crop (b, fig. 156).

Digestive canal of an Eagle.

In those birds, again, the food of which is
exclusively of the vegetable kind, as grains
and seeds, and of which consequently a great
quantity must be taken to produce the ade-
quate supply of nutriment, and where the
cavity of the gizzard is very much diminished
by the enormous thickness of its muscular
coat, the crop is more developed, and takes a
more important share in the digestive process.
Instead of a gradual cylindrical lateral dila-
tation of the gullet, it assumes the form of a

globular or oval receptacle appended to that /
tube, and rests upon the elastic fascia which ‘
connects the clavicles or two branches of the ;\

furculum together. &
In the common Fowl the crop is of large
size and single (b, fig.157: I, fig. 171), but in
iA

AVES.

the Pigeon it is double, consisting of two lateral
oval cavities (6 c, fig. 158).

The dilatation of the esophagus to form
the crop is more gradual in the Ducks
than in the Gallinaceous birds. The crop is”
wanting in the Swans and Geese. ;

The disposition of the muscular fibres of the
crop is the same as in the cesophagus, but the
muciparous follicles of the lining membrane are —
larger and more numerous. ‘This difference is
most conspicuous in the ingluvies of the grani-
vorous birds, where it is not merely a temporary
reservoir, but in which the food is mixed with
the abundant secretion of the glands, and be-
comes softened and macerated, and prepared for
the triturating action of the gizzard and the sol-
vent power of the gastric secretion.

The change which the food undergoes in
the crop is well known to bird-fanciers. If
a Pigeon be allowed to swallow a great quan-
tity of peas, they will swell to such an extent
as almost to suffocate it. .

The time during which the food remains
in the crop depends upon its nature. In a
common Fowl animal food will be detained
about eight hours, while half the quantity
of vegetable substances will remain from six-
teen to twenty hours, which is one among
many proofs of the greater facility with

which animal substances are digested. Mr.
Hunter made many interesting observations
on the crop of Pigeons, which takes on a

Su
i td

Fig. 158.

z
AAMT
f N i <

SARA
BONS

aS

Crop of a Pigeon.

secreting function during the breeding season,
for the purpose of supplying the young pi-
geons in the callow state with a diet suitable
to their tender condition.* An abundant se-
cretion of a milky fluid of an ash-grey colour, —
which coagulates with acids and forms curd,
is poured out into. the crop and mixed with

* Animal Economy, p. 235.

Se ee ee ee ee ee a

AVES. 319

the macerating grains. This peared is
the nearest approach in the class of Birds to
the great characteristic function, the presence of
whose special apparatus, the mammz, has af-
forded the universally recognized title of the
higher division of warm-blooded Vertebrata ;
and the analogy of the ‘ Pigeon’s milk’ to the lac-
teal secretion of the mammalia has not escaped

popular notice. In the subjoined figure one side _

of the crop(b), shows the ordinary structure of the
parts, the other (e), the state of the cavity during
the period of rearing the young /fig. 158).

e canal which is continued from the in-
gluvies to the stomach was called by Hunter
the second or lower esophagus; at its com-
mencement it is narrower and more vascular
than that part of the gullet which precedes
the crop, but gradually dilates into the first
or glandular division of the stomach, which
is termed the ‘ proventriculus’ (ventriculus
succenturiatus, bulbus glandulosus, echinus,
infundibulum, the ‘ cardiac cavity’ of Home),
(c, fig. 156, 157, 166).

In birds with a wide esophagus (a, fig.165),
as the omnivorous and _piscivorous tribes, the
commencement of the proventriculus (e, fig.
165), is not indicated by any change in the di-
rection or diameter of the tube, but only by
its greater vascularity, by the difference in the
structure of the lining membrane, and by
the stratum of glands which open upon its
inner surface, and which are its essential cha-
racteristic (c. fig.
159). Hence it is
by some compara-
tive anatomists re-
garded as a part of
the cesophagus.

The proventri-
culus varies, how-
ever, in form and
magnitude in dif-
ferent birds. In
the Rasores it is
larger than the ceso-
phagus, but much
smaller than the
gizzard. In the
Psittacide and Ardeida (Parrot and Stork
tribe) it is larger than the gizzard and of a
different form. In the Ostrich the proventri-
culus is four or five times larger than the
triturating division of the stomach, being con-
tinued down below the liver, and then bent up
upon itself towards the right side before it termi-
nates in the gizzard, which is placed on the right
and anterior part of this dilatation.

The experiments of Reaumur, Spallanzani,
and Hunter, and those of Tiedemann and
Gmelin, prove that the secretion of the pro-
ventricular or gastric glands is analogous to the
gastric juice in man and mammalia.

In the majority of birds the gastric follicles
are simple, having no internal cells, dilated
fundus, or contracted neck; but from their
external blind extremity proceed with an
uniform diameter to their internal orifice. This
form obtains in the zoophagous and omnivorous
birds. In the Dove-tribe the follicles are of

a conical shape.. In the Swan they are tubuli-
form; in the Goose and Turkey they present
internal loculi; in the Ostrich and Rhea these
loculi are so developed that each gland forms
a racemose group of follicles, terminating by
a common aperture in the proventriculus.

The subjoined figures from Home’s Com-
parative Anatomy (vol. ii. pl. lvi.) show the
different forms of the solvent or proventricular
glands in different birds.

Fig. 160.

3 i Gly Eagle.

E 4 Lb ; Gannet.

& b Wbible Sea-gull.
( 66860 Pigeon.

Swan.

Goose.

Fowl.

Turkey.

Por vegetable food.

Rhea.

Ostrich.

The gastric glands are variously arranged.
Among the Raptores, we find them in the
Golden Eagle disposed in the form of a broad
compact belt; in the Sparrow-Hawk this belt
is slightly divided into four distinct portions.
In the Insessores the glands are generally
arranged in a continuous zone around the pro-
ventriculus; but in some of the Syndactyli,
as the Hornbill, the circle is composed of the
blending together of two large oval groups.
Among the Scansores the Parrots have the
gastric glands disposed in a continuous white
circle, which is at some distance from the small
gizzard. In the Woodpeckers the glands are
arranged in a triangular form, with the apex
towards the gizzard. In the Toucan they are
dispersed over the whole proventriculus, but
are more closely aggregated near the gizzard ;
the lining membrane of the cavity is reticulate,
and the orifices of the glands are in the inter-
spaces of the meshes. ;
Among the Rusores the Pigeon shows its
affinity to the Passerine Birds in having the gas-
tric glands of a simple structure, and arranged

320 AVES.

in a zonular form : they are chiefly remarkable
for their large cavity and wide orifice. In the
Common Fowl and Turkey the glands are more
complex, and form a complete circle.

In the Cursores the arrangement of the glands
is different in almost every genus.

In the Ostrich they are of an extremely
complicated structure, and are extended in
unusual numbers over an oval space on the
left side of the proventriculus, which reaches
from the top to the bottom of the cavity, and
is about four inches broad.

The Rhea differs from the other Struthious
birds in having the solvent glands aggregated
into a single circular patch, which occupies
the posterior side of the proventricular cavity.

In the Emeu the gastric glands are scattered
over the whole inner surface of the proven-
triculus, and are of large size; they terminate
towards the gizzard in two oblique lines.

In the Cassowary the glands are dispersed
over the proventriculus with a similar degree
of uniformity ; but they are smaller, and their
lower boundary is transverse.

Among the Grallatores, the Marabou, or
Gigantic Crane, (Ciconia Argala and Ma-
rabou,) has the nearest affinity to the Rhea
in the structure and disposition of the gastric
glands; they are each composed of an aggre-
gate of five or six follicles, terminating in the
proventriculus by a common aperture; and
they are disposed in two compact oval masses,
one on the anterior, the other on the posterior
surface of the cavity. In the Heron (Ardea
cineria) the solvent glands are of more sim-
ple structure, and are more dispersed over the
proventriculus; but still they are most nume-
rous on the anterior and posterior surfaces.
In the Flamingo the gastric glands are short
and simple follicles, arranged in two large oval
groups, which blend together at their edges.

The Natatores present considerable differ-
ences among themselves in the disposition of
the solvent glands. In the Cormorant ( Pha-
lacrocorax carbo) they ave arranged in two
circular spots, the one anterior and the other
posterior; while in the closely allied. genus
the Sula, or Gannet, they form a complete belt
of great width, and consequently are extremely
numerous. In this respect the Gannet, or
Solan Goose, has a nearer affinity to the
Pelecan, with which both birds were generically
associated by Linneus.

In the Sea-Gulls the gastric glands form a
continuous zone ; and in the Little Auk ( Alca
Alle ) they are spread, according to Sir Everard
Home, over a greater proportional extent of
surface than in any other bird that lives on
animal food, and the form of the digestive
organs is peculiar to itself. The cardiac cavity
or proventriculus appears to be a direct con-
tinuation of the cesophagus, distinguished from
it by the termination of the cuticular lining and
the appearance of the solvent glands. The cavity
is continued down with very gradual enlarge-
ment below the liver, and is then bent up to
the right side, and terminates in the gizzard.
The solvent glands are situated at the an-
terior or upper part of the cavity every where

surrounding it, but lower down thay tieipeine
ere

cipally upon the posterior surface, and w

it is bent upwards towards the right side they

are entirely wanting. In the graminivorous
lamellirostral Water-birds, as the Swan, Goose,
&c. the gastric glands have a simple elongated

exterior form, but have an irregular or cellular

internal surface: they are closely arranged so
as to form a complete zone.

Tn general the muscular or pyloric division
of the stomach immediately succeeds the glan-
dular or cardiac division; but in some Birds,
as the Auk and Parrots, there is an intervening
portion without glands. Itis always widely dif-
ferent in structure, and hence has received a dis-

tinct name, the‘ gizzard’ (gigerium, ventriculus ~
’ g B's ?

bulbosus ).

The gizzard is situated below or sacrad of
the liver, on the left side and dorsal aspect of
the abdomen, generally resting on the mass
of intestines; although, according to Blumen-
bach, the Nutcracker and Toucan, as well as
the Cuckoo, differ in having the gizzard situated
on the abdominal part of the cavity. Hence
this peculiarity not being restricted to the Cuc-
koo affords no explanation, as has been sup-
posed, why it should not incubate. In the Owl,
also, the gizzard adheres to the membrane cover-
ing the internal surface of the abdominal muscles.

In all birds the gizzard forms a more or less
lengthened sac, having at its upper part two
apertures ; one of these is of large size, com-
municating with the proventriculus (a, fig. 161,
162), the second is in close proximity with,
and to the right side of the preceding, leading
to the duodenum (6, fig. 161); below these
apertures the cavity extends to form a cul-de-
sac (c, fig. 161, 162.) At the middle of the
anterior and posterior parts. of the cul-de-sac
there is a tendon (e, fig. 156, 157) from which
the muscular fibres radiate.

Fig. 161.

oO

AVES.

The differences in the structure of the gizzard
resolve themselves into the greater or less extent
of the tendons, and the greater or less thick-
ness of the muscular coat, and of the lining
membrane.

In the Raptores the gizzard (d, fig. 156)
assumes the form of a mere membranous cavity,
in accordance with the animal and easily di-
gestible nature of their food. The muscular
coat is extremely thin; the fibres principally
radiate from small tendons (e, fig. 156), and
there are some longitudinal fibres beneath the
radiating or external layer.

In the Rasores and lamellirostral Natatores
it exhibits the structure to which the term giz-

_zard can be more appropriately applied. The
muscular fibres are distinguished by their
unparalleled density of texture and deep
colour, and are arranged in four masses; two
are of a hemispherical form, and their closely-
packed fibres run transversely to be connected
to very strong anterior and posterior tendons
(e, fig. 157, 162); they constitute the sides
of the gizzard, and are termed the digastric
muscles or ‘ musculi laterales’ (d, fig. 161,
162): between these, at the end of the gizzard,
are the two smaller and thinner muscles called
‘ musculi intermedii’ ( f, fig. 162). There are
likewise irregular bands placed about the cir-
cumference of the gizzard.

Fig. 161 shows the relative thickness of the
musculi laterales in the gizzard of a Swan, and
Jig. 162 that of the musculi intermedii and
tendon. —

Fig. 162.

— iT mg Wy
ne /

Gizzard of a Swan.

The internal coat of the gizzard (c, h, fig. 162)
is extremely hard and thick, and being of a
horny or cuticular nature, it is liable to be
increased by pressure and friction, and as it is
most subject to these influences at the parts of
the gizzard opposite the musculi laterales, two
callous buttons are there formed, (g, g, fig. 162).
It is here that the fibrous structure of the lining
membrane can be most plainly seen :—and it
is worthy of observation that the fibres are not
perpendicular to the plane of the muscles but

VOL. I.

321

oblique, and in opposite directions, on the two
sides. Elsewhere the cuticular lining is dis-
posed in ridges and prominences (h, fig. 161,
162), which vary in different birds, but are

retty constant in the same species. Carus*

as recently figured the gizzard of a Petrel
(Procellaria glacialis), the lining membrane
of which is disposed in a pavement of small
square tubercles, like the gastric teeth of some
Mollusca.

The cavity of the gizzard is so encroached
upon by the grinding apparatus, that it is
necessarily very small, the two horny callosities
having their internal flat surfaces opposed to
one another, like ‘ millstones.’ A crop is as
essential an appendage to this structure as the
‘hopper’ to the mill; it receives the fuod as
it is swallowed, and supplies it the gizzard in
small successive quantities as it is wanted.

Between the stomach of the carnivorous
Eagle, and that of the graminivorous Swan,
there are numerous intermediate structures, but
it is necessary to observe that the animal or
vegetable nature of the food cannotalways be pre-
dicated of from the different degrees of strength
in the gizzard. Hard-coated coleopterous in-
sects, for example, require thicker parictes for
their due comminution than pulpy succulent
fruits.

In the subgenus Euphones, among the Tana-
gers, the muscular or pyloric division of the
stomach is remarkably small and not sepa-
rated from the duodenum by a narrow pylorus.{

The parietes of the gizzard, like those of other
muscular cavities, become thickened when
stimulated to contract on their contents with
greater force than usual. In the Hunterian
collection this fact is well illustrated by pre-
parations of the gizzard of the Sea-gull in the
natural state, and that of another Sea-gull which
had been brought to feed on barley. The
digastric muscles in the latter are more than
double the thickness of those in the Sea-gull
which had lived on fish.§

The immediate agents in triturating the food
are hard foreign bodies, as sand, gravel, or peb-
bles. The well-known habit in the granivorous
birds of swallowing stones with their food has
been very differently explained. Blumenbach
observes that ‘ Ceesalpinus considered it rather

\\ as a medicine than as a common assistance to

digestion; Boerhaave, as an absorbent for the

) acid of the stomach; Redi, as a substitute for

teeth; Whytt, as a mechanical irritation, adapt-
ed to the callous and insensible nature of the
coats of the stomach.’ Spallanzani rejected all
supposition of design or object, and hazarded
the stupid observation that the stones were
swallowed from mere stupidity.

* Tabule Anatomiam Comparativam illustrantes,
fol. pars iv. 1835. ;

+ Thus we find in Parrots, where the gizzard is
remarkably small, that a crop is present. A like
receptacle exists also in the Flamingo, in which the
gizzard is small but strong.

¢ Carus ut supra, tab. vi. fig. iv. _

§ See Home, Comp. Anatomy, vol. i. p. 271, and
Hunter, Animal Giconomy, p. 221, where it is re-
lated that a similar change was effected by c!.anging
the food of a tame Kite.

Y

322

Pigeons, however, are known to carry gravel
to their young. Gallinaceous birds grow lean
if deprived of pebbles; and no wonder, since
experiment* shows that unless the grains of
corn are bruised, and deprived of their vitality,
the gastric juice will not act upon or dissolve
them. The observations and experiments of
Hunter have completely established the rationa-
lity and truth of Redi’s opinion, that the peb-
bles perform the vicarious office of teeth.

Hunter inferred from the form of hair-balls
occasionally found in the stomach of Cuckoos,t
that the action of the great lateral muscles of
the gizzard was rotatory. Harvey appears to
have first investigated, by means of the ear, as
it were in anticipation of the art of auscultation,
the actions which are going on in the interior of
an animal body, in reference to the motions. of
the gizzard. He observes, ( De Generatione
Animalium, in Opera Omnia, 4to. p. 208,) “ Fal-
conibus, aquilis, aliisque avibus ex preda viven-
tibus, si aurem prope admoveris dum ventricu-
lus jejunus est, manifestos intus strepitus,
lapillorum illuc ingestorum, invicemque colli-
sorum percipias.” And Hunter observes,
(Animal Ciconomy, p. 198,) “ the extent of
motion in grindstones need not be the tenth of
an inch, if their motion is alternate and in con-
trary directions. But although the motion of
the gizzard is hardly visible, yet we may be
made very sensible of its action by putting the
ear to the sides of a fowl while it 1s grinding
its food, when the stones can be heard moving
upon one another.”

Tiedemann believes that the muscles of the
gizzard are in some degree voluntary, having
observed that when he placed his hand oppo-
site the gizzard, its motions suddenly stopped.

The pyloric orifice of the gizzard is guarded by
a valve in many birds, especially in those which
swallow the largest stones. This valve in the
Ostrich is formed by a rising of the cuticle
divided into six or seven ridges, which close
the pylorus like a grating, and allow only stones
of small size to pass through. In the Touraco
the pylorus projects into the duodenum in a
tubular form. There is a double valve at the
pyloric orifice in the Gannet, and a single large
valvular ridge at the same part in the Gigantic
Crane. In this species and some other Waders,
as the Heron and Bittern; also in the Pelecan,
and, according to Cuvier, in the Penguin and

* Grains of barley, inclosed in strong perforated
tubes, pass through the alimentary canal unchanged.
Dead meat, similarly introduced into the gizzard,
is dissolved.

+ The hairs of caterpillars devoured by this bird
are sometimes pressed or stuck into the horny lining
of the gizzard, instead of being collected into a loose
ball. They are then neatly pressed down in a regular
spiral direction, like the nap of a hat, and have
often been mistaken for the natural structure of the
gizzard. One of these specimens exhibited as such
to the Zoological Society was sent to me for exami-
nation, when, upon placing some of the supposed
gastric hairs under the microscope, they exhibited
the peculiar complex structure of the hairs of the
larva of the Tiger-moth (Arctia Caja), and the
broken surface of the extremity which was stuck
into the cuticular lining was aint discernible.
See Proceedings of Zool. Soc, 1834, p. 9.

AVES.

Grebe, there is a small but distinct cavity inter-
posed between the gizzard and intestine. An
analogous structure is found in the Crocodile.

The intestines reach from the stomach to the

cloaca ; in relative length they are much shorter
than in the mammalia. In the Toucan, for
example, the whole intestinal canal scarcely
equals twice the length of the body, in-
cluding the bill. The canal is divided into
small and large intestines, sometimes by an
internal valve, sometimes by the insertion of a
single cecum, but most generally by those of two
ceeca, which are always opposite to one another.
In a few instances there is no such distinction.
The small intestines and ceca are longest in
the vegetable feeders. The large intestine is,

with one or two exceptions, very short and
straight in all birds.

The course of the small intestine varies
somewhat in the different orders of Birds;
it is always characterized by the elongated fold
or loop made by the duodenum, (ff; fig. 163,)

Fig. 163.

Abdominal viscera of a Pigeon.

which fold receives the pancreas (q g) in its
concavity.

In the Raptores the intestines are generally
disposed as follows :—

The duodenum forms a long and broad
fold, the lower part of which is commonly
bent or doubled upon itself: the intestine then
passes backwards on the right side of the ab-
domen, crosses to the left, and is disposed in
deep folds upon the edge of a scolloped mesen-
tery ; towards its termination the ileum passes
up behind the stomach and adheres to it, having
here but a narrow mesentery; then passing down
the posterior part of the abdomen the ileum
makes another loose fold and ends in the rec-
tum, which is continued straight to the cloaca.*
In the Owls the last fold of the ileum is nearly

as long as the duodenal fold, and the ceca

adhere to each side of the fold.
In the Diurnal Raptores the intestinal canal

7 a
according to their natural arrangement.

Jig. 156 the intestines are not represented ~

al A a ee, i i ee

AVES. 323

is only twice the length of the body, except in
the fish-eating Osprey, in which the intestines
are very narrow, and are to the length of the
bird itself as eight to one.

~ In the Insessores the scolloped folds of the
small intestine are narrower and longer than in
the Raptores, and the ileum generally adheres
to the duodenal mesentery and pancreas in-
stead of to the stomach, prior to passing down
to form its last fold and to terminate in the
rectum. In the Raven the small intestines are
oh sed at their commencement in concentric
olds.

Among the Scansores the Cuckoo presents
the following disposition of the intestinal
canal: after the usual long and narrow duo-
denal fold, the ileum* makes a fold which is
widened at the end, ‘it then forms a close fold
upon itself, at the termination of which the
rectum commences. In the Maccaw the
course of the small intestine is somewhat
peculiar: after forming the duodenal fold,
it is disposed in three distinct packets of
folds : the intestine, after forming the first two,
passes alternately from one to the other, de-
scribing shorter folds upon each ; it then forms
the third distinct fold, which is a long one,
at the termination of which the ileum adheres
closely to the right side of the gizzard, and then
passes backwards and dilates into the rectum.

In the Rasores the Dove-tribe have the
small intestines disposed in three principal

’ folds ; the first is the duodenal fold (ff, fig.

163); the second is along and narrow fold,
coiled and doubled upon itself, with the turns
closely connected together, (k, fig. 163); the
third is also a long fold, which is bent or
twisted, (k’, fig. 163.) In the common Fowl
the duodenum is disposed in a long simple
loop; the ileum passes towards the left, and is
disposed in loose folds on the right and lower
edge of the mesentery; the ileum before its
termination passes up behind the preceding

folds, and is accompanied as far as the root

of the mesentery by the two ceca, which
there open into the commencement of the large

intestine.

The Ostrich presents the most complicated
course of the intestinal canal in the whole
class of birds. The duodenal fold is about
a foot in length, and the returning part makes
a bend upon itself before it reaches the py-

lorus ; the intestine then turns down again

behind the duodenal folds and gradually ac-
quires a wider mesentery. The ileum after a
few folds ascends towards the left side, accom-

panied by the two long caca, and becomes
‘again connected with the posterior part of the

duodenal mesentery; beyond which the coca

enter the intestine behind the root of the me-

sentery, and the large intestine commences.
This part differs from the rectum in other

binds im its great extent, being nearly double

the length of the small intestines, and being
disposed in folds upon a wide mesentery. It
terminates by an oblique valvular aperture in
a large urinary receptacle. In the Bustard the

* There is seldom any part of the small intestine
empty so as to merit the name of jejunum.

rectum is a foot in length, which is the nearest
approach to the Ostrich which the rest of the
class make in this respect.

The small intestines in the Gradlatores are
characterized by their small diameter and long
and narrow folds; these are sometimes ex-
tended parailel to one another, as in the Crane
and Coot; or folded concentrically in a mass,
as in the Curlew and Flamingo. In the latter
species the duodenal fold is four inches in
length; then the small intestines are disposed
in twenty-one elliptical spiral convolutions,
eleven descending towards the rectum and ten
returning towards the gizzard in the interspaces
of the former.

Many of the Natatores present a concentric
disposition of the folds of the small intestines
similar to the Flamingo. Home* has given
figures of this structure in the intestines of the
Sea-mew (pl. cviii.); the Gannet or Solan
Goose (pl. cvi.); and the Goose (pl. cxi.).
It likewise obtains in the Pelecan and Cor-
morant.

The arrangement of the muscular fibres of
the intestine is the same as in the esophagus,
the external layer being transverse, the internal
longitudinal.

The villi of the lining membrane manifest an
analogy with the covering of the outer skin,
being generally much elongated, so as to pre-
sent a downy appearance when viewed under
water. There are, however, great varieties in the
shape and length of the villi. In the Emeu
they consist of small lamelle of the lining
membrane folded like the frill of a shirt. In
the Ostrich the lamelle are thin, long, and nu-
merous. In the Flamingo they are short and
arranged in parallel longitudinal zig-zag lines.

In many birds a small diverticulum is ob-
served in the small intestine, which indicates
the place of attachment of the pedicle of the
yolk-bag in the embryo (m, fig. 157). We
have found this process half an inch in length
in the Gallinule, and situated seventeen inches
from the pylorus. In the Bay Ibis ( Ibis falci-
nella) the vitelline ccecum is an inch in length.

The birds in which the caca coli have been
found wanting are comparatively few, though
such examples occur inall the orders. These
exceptions are most frequent among the Scan-
sores, in which the cceca are absent in the Wry-
necks, the Toucans, theTouracos, the Parrot tribe,
and according to Cuvier in the Woodpeckers.t
In the Insessores the coeca are deficient in the
Hornbill and the Lark. Among the Grai-
latores, we have found them wanting in a Spoon-
bill. In the Natatores they are absent in the
Cormorant. The Herons, Bitterns, and, occa-
sionally, the Grebes afford the rare examples of
a single ccecum, which is also remarkably short.

In the Raptores the diurnal and nocturnal
tribes differ remarkably in the length of the
ceca. They are each less than half an inch in
length in the Eagles and Vultures, but are occa-
sionally wanting in the latter. Cuvier states

* Comparative Anatomy, vol. ii.
¢ In the Poppinjay ( Picus viridis, Linn.) we have
found two small cceca, so closely adhering to the
intestine as easily to be overlooked. .
¥

324

that the ¢coeca are deficient in the greater part
of the Diurnal Raptores, but we have observed
them in the Halietus Albicilla, Aquila Chry-
saetos, Astur palumbarius, and Buteo nisus.
They seldom exceed the length above-men-
tioned (g, fig. 156), and in the Secretary Vul-
ture they form mere tubercles. In the Barn
Owl the coca severally measure nearly two
inches in length, and are dilated at their blind
extremities; they are proportionally developed
in the larger Strigida.

In the Insessores they are invariably very
short where present. Among the Scansoriad
Genera which possess the ceca, these parts
are found to vary in length, measuring in the
Cuckoo and Wattle-bird (Glaueopis ), each
half an inch; while in the Scythrops, or New-
Holland Toucan, the ceca are each two inches
tong, and moderately wide.

In the Rasores the cceca present considerable
varieties. In the Pigeons (g, fig. 163) they are
as short as in the Insessorial order, and are
sometimes wanting altogether, as in the Crown-
pigeon. In the Guan ( Penelope cristata ) each
ccecum is about three inches in length; while in
the Grouse each coecum measures a yard long,
being thus upwards of three times the length
of the entire body. The internal surface of
these extraordinary appendages to the alimen-
tary canal is further increased in the Grouse by
being disposed in eight longitudinal folds,
which extend from their blind extremities to
within five inches of their termination in the
rectum. We have always found the ceca in
this species filled with a homogeneous pulta-
ceous matter without any trace of the heather
buds, the remains of which are abundant in the
feecal matter contained in the ordinary tract of
the intestines.

In the Peacock the ceca measure each
about one foot in length; in the Partridge
about four inches; in the common Fowl and
other Phasianide the ceca are each about one-
third the length of the body; they commence
by a narrow pedicle, which extends about half
their length, and then’they begin to dilate into
reservoirs for the chyme (g, fig. 157).

In the Cursores the ceca again present very
different degrees of development. In the
Emeu they are narrow and short. In the Cas-
sowary they are wholly deficient; while in the
Ostrich they are wide and upwards of two feet
in length, and their secreting and absorbing
parietes are further increased by being pro-
duced into a spiral valve, analogous to that
which exists in the long cecum of the Hare
and Rabbit.

In the Grallatores the two ceca are gene-
rally short where present; they attain their
greatest development in this order in the De-
moiselle, where the length of each ceecum is
five inches; and they are also large in the Fla-
mingo, where they each measure nearly four
inches, and are dilated at their extremities,
presenting with the gizzard, crop, lamellated
beak, and webbed feet, the nearest approach
to the Andtide of the following order.

In the Natatores the ceca, where they are
present, vary in length according to the nature
of the food, being very short in the fish-eating

AVES. |
Penguin, Pelecan, en ang long in the

Duck, Goose, and other vegetable feeding

Lamellirostres. ;

In the crested Grebe ( Podiceps cristatus ),
Yarrell detected two ceca, each measuring
3-16ths of an inch in length. In the Canada
Goose the same indefatigable observer found
the cceca each nine inches in length, and in
the White-fronted Goose the same mea-
sured severally thirteen inches. ey have
the same length in the Black Swan. In the

Wild Swan the coeca measure each ten inches -

in length, while in the tame species they are
each fifteen inches long.

As digestion may be supposed to-go on less.

actively in the somnolent, night-flying Owls,
than in the high-soaring Diurnal Birds of Prey,
an additional complexity of the alimentary
canal for the purpose of retaining the chyme
somewhat longer in its passage, might naturally
be expected; and the enlarged ceca of the
Nocturnal Raptores afford the requisite adjust-
ment in thiscase. For, although the nature
of the food is the same in the Owl* as in the
Hawk, yet the differences of habit of life call
for corresponding differences in the mechanism
for its assimilation.

In the Rasorial Order, where the nature of
the food differs so widely from that of the
Birds of Prey, the principal modification of
the digestive apparatus obtains in the more
complex structure of the crop, proventriculus,
and above all the gizzard; but with respect to
the coeca, as great differences obtain in their
development as in the Raptores.
differences are explicable on the same prin-
ciple as has just been applied towards the
elucidation of the differences in the size of the
ceca in the Ruptores. Where the difference
in the locomotive powers is so great in the
Dove-tribe and the common Fowl; where the
circulating and respiratory systems must be so
actively exercised to enable the Pigeon to take
its daily flights and in some species their an-
nual migrations—a less complicated intestinal
canal may naturally be supposed with such
increased energy in the animal and vital fune-
tions to do the business of digestion, than in
the more sluggish and terrestrial vegetable
feeders; and accordingly we find that the
requisite complexity of the intestinal canal is
obtained by an increased development of the
ceecal processes in them, while in the Colum-
bide the ceca remain as little developed as
in the Insessores, which they resemble in powers
of flight. If we regard the cceca as excretive
organs, their differences in the above orders may
be in like manner explained by their relations
to the locomotive and respiratory functions.

In the Cursores the development of coca
seems to have reference to the quantity of food,
and the ease with which it may be obtained,
according to the geographical position of the
species. In the Cassowary, which is a native

* The indigestible parts of the prey of the Owl
do not pass into the intestine, but are regularl;
east or regurgitated from the stomach ; the fengih
of the ceeca cannot, therefore, be accounted for on
Macartney’s supposition of their being receivers of
those parts.

Now these .

SS ee

AVES.

of the fertile districts of a tropical country, ve-
getable food of a more easily digestible nature
may be selected, and it need not be detained un-
necessarily long, where a fresh supply can be
so readily procured. But in the Ostrich, which
dwells amidst arid sands and barren deserts,
every contrivance has been adopted in the struc-
ture of the digestive apparatus to extract the
whole of the nutritious matter of the food which
is swallowed.

In the Grallatores, where no material dif-
ferences of locomotive powers or means of
obtaining food exist, the ceca present in their
development a direct relation to the nature of the
food, and are most developed in the Gruide.
The same holds good in the Natatores.

Why the increased extent of intestinal sur-
face in the above different cases should be
chiefly obtained by the elongation of the ceca,
will appear from the following considerations.
In consequence of the stones and other foreign
bodies which birds swallow, it is necessary that
there should be a free passage for these through
the intestinal canal, which is therefore generally
short and of pretty uniform diameter. In the
Omnivorous birds of the tropics,as the Hornbills,
Toucans, Touracos, and Parrots, which dwell!
among ever-bearing fruit-trees, the rapid pas-
sage of the food is not inconsistent with the
extraction of a due supply of nourishment, but
is compensated by the unfailing abundance of
the supply. Butwhere a greater quantity of the
chyle isto be extracted from the food, and where,
from the nature of the latter, a greater proportion
of foreign substances is required for its tritura-
tion,—while the advantages of a short intestinal
tract are obtained, the chyme is at the same
time prevented from being prematurely expelled
by the superaddition of the two cecal bags
which communicate with the intestines by
orifices that are too smal! to. admit pebbles or
undigested seeds, but which allow the chyme to

‘in. Here, therefore, it is detained, and |

chylification assisted by the secretion of the
ewcal parietes, and the due proportion of nutri-
ment extracted.

The large intestine is seldom more than a
tenth part of the length of the body, and,
except in the Ostrich and Bustard, is continued
straight from the coca to the cloaca; it may
therefore be termed the rectum rather than the
colon. It is usually wider than the small in-
testine, and its villi are coarser, shorter, and
less numerous. The rectum (a, fig. 164)
terminates by a valvular circular orifice (6),
in a more or less dilated cavity, which is the
remains of the allantois, and now forms a
rudimental urinary bladder, (c d). The ureters
{4 h), and efferent parts of the generative ap-
paratus (f, g,) open into a transverse groove
at the lower part of the urinary dilatation,
and beyond this is the extemal cavity which
lodges, as in the Reptiles and Marsupial and
Monotrematous Quadrupeds, the anal glands
and the exciting organs of generation. The anal
follicles in Birds are lodged in a conical glan-
dular cavity, which communicates with the pos-
terior part of the outer compartmentof the cloaca,
and has obtained from its discoverer the name of

325

Bursa Fabricii (k). Berthold considers this
ore as a subdivision of the urinary bladder in

irds, and Geoffroy St. Hilaire as the analogue
of Cowper’s glands.

Cloaca of the Condor.

Digestive glands. — The liver is large in
Birds, and proportionally larger in the Aquatic
species than in Birds of Prey. In the former

Fig. 165.

CAA

Aan NOY nn Ana

Posterior view of the biliary and pancreatic due
in the Hornbill.

326

it bears a proportion of one-tenth, in some of
the latter of one-twenty-ninth part of the entire

body.

The liver (m m, fig. 163, 165) is situated
a little above the middle of the thoracic-abdo-
minal cavity, with its convex surface towards
the abdominal parietes, and its concavity turned
towards the subjacent viscera: the right lobe
covers the duodenum, pancreas, and part of the
small intestines; the left lobe covers the pro-
ventriculus and part of the gizzard; and the
apex of the heart is received between the upper
ends of these principal lobes. The liver is, as
it were, moulded upon all these parts, and pre-
sents corresponding depressions where it comes
in contact with them.

It is generally divided into two nearly
equal lobes, which are often separated ‘for
a short extent, and connected together by a
narrow isthmus of the glandular substance.
In some birds, however, as in the Pigeon,
Cormorant, Swan, and Goose, there is a third,
smaller lobe, situated at the back of the liver
between the lateral lobes, which from its situ-
ation appears analogous to the lobulus Spigelii
of Mammalia. In the Common Fow! the left
lobe is occasionally cleft so deeply as to form
two lobes on that side. In some species the
right lobe exceeds the left in size ;; this is most
remarkable in the Bustard, in which the right
lobe extends into the pelvis. In the Eagle,
however, the left lobe has been observed to be
the largest. Each lobe is invested by a double
membranous tunic, one embracing it closely,
the other surrounding it loosely, like the peri-
cardium of the heart. They are formed by
lamine of the peritoneum, which seems to
split at the exterior thin edge of the liver into
four layers, two being continued upon the
anterior and posterior surfaces adhering to them,
the other two forming the loose exterior cap-
sule.

The principal ligament of the liver is formed
by a large and strong duplicature of the peri-
toneum, which divides the abdomen longitu-
dinally like the thoracic mediastinum in Mam-
malia. It is reflected from the linea alba and
middle line of the sternum upon the pericar-
dium, and passes deeply into the interspace of
the lobes of the liver; it is attached to these
lobes through their whole extent, and connects
them: below to the gizzard on one side and to the
duodenal fold on the other: the lateral and
posterior parts of the liver are attached to the
contiguous air-cells; and the whole viscus is
thus kept steady in its situation during the
rapid and violent movements of the bird. The
ligament first described is analogous to the fal-
ciform ligament of Mammalia; and, although
there is no free margin inclosing a round liga-
ment, yet the remains of the umbilical vein
may be traced within the duplicature of the
membranes forming the septum. As the mus-
cular septum between the thorax and abdomen
is wanting, there is consequently no coronary
ligament; but the numerous membranous pro-
cesses which pass from the liver to the sur-
rounding parts amply compensate for its ab-
sence.

AVES.

The liver is of a lighter colour enter a
flight than in the heavier Water-fowl.
lobe has its hepatic artery and vena porte.
The hepatic arteries are proportionally small,
but the portal veins are of great size, being
formed not only by the veins of the intestinal —
canal, pancreas, and spleen, but also by the
inferior emulgent and sacral veins. The blood,
which has circulated in the liver, is returned
to the inferior cava by two vene hepatice.
There are occasionally some smaller hepatic
veins in addition to the two principal ones.
The coats of the portal and hepatic veins ap-
pear to be equally attached to the substance
of the liver.

The biliary secretion is carried out of the liver
by two and sometimes three ducts; one of these
terminates directly in the intestine, and is a ‘he-
patic duct’ (n,n, fig. 165); the other enters the.
gall-bladder, and isa ‘ cyst-hepatic duct’ (0’, fig.
165); the cystic bile is conveyed to the duo-
denum by a ‘ cystic duct’ (0, fig. 165). Where,
as in a few instances, the gall-bladder does not
exist, both hepatic ducts terminate separately
in the duodenum (n,n, fig. 163); but in no
case is there a single ductus communis cho-
ledochus as in Mammalia.

The gall-bladder (p, fig. 165) is situated
near the mesial edge of the concave or under.
side of the right lobe, and is commonly lodged
in a shallow depression of the liver; but some-
times, as in the Eagle, Bustard, and Cormorant,
only a very small part of the bag is attached to the
liver. It has the same structure asin Mamma-
lia, manifesting no visible muscular tunic, and
having its inner surface delicately reticulated.

The gall-bladder is present in all the Rap-
tores, Insessores, and Natatores. It is want-
ing in a great proportion of the Scansores, as
in the Genus Rhamphastos and in the whole
of the Psittacide and Cuculide. Among the
Rasores the gall-bladder is constantly deficient
in the Columbide or Dove-tribe alone, in which
the cceca are shorter than in any other vege-
table feeder: (n n, fig. 163, are the two he-
patic ducts terminating apart from one another
in the Pigeon.) The gall-bladder is occasion-
ally absent, according to the French Acade-
micians, in the Guinea-fowl; and they also
found it wanting in two out of six Demoi-
selles ( Anthropoides Virgo). The gall-blad-
der is small and sometimes absent in the.
Bittern: it is always wanting in the Ostrich. _

The bile, as before observed, passes directly
into the gall-bladder, and not by regurgitation
from a ductus choledochus ; the cyst-hepatice
duct arises from the right lobe, and is con-
tinued in some birds along that side of the
bag which is in contact with the liver, where it
penetrates the coats of the cyst and terminates
about one-third from the lower or posterior end.
In the Horn-bill we found it passing over the
upper end of the bladder to the anterior or free
surface, and the cystic duct continued from
the point where the cyst-hepatic duct opened
into the bladder; so that the cystic duct had
a communicaton both with the reservoir and _
the cyst-hepatic duct; being somewhat ana-_
logous to the ductus communis choledochus; ©

AVES.

{see fig. 165, where x represents the orifice by
which the bile passes both in and out of the
gall-bladder.)

In the Goose the cyst-hepatic duct termi-
nates by a very small orifice, surrounded
by a smooth projection of the inner mem-
brane, which, aided by the obliquity of the
duct, acts as a valve and prevents any re-
gurgitation towards the liver. The cystic duct
here passes abruptly from the posterior ex-
tremity of the gall-bladder, which is not pro-
longed into aneck. The duct makes a turn
round the end of the bag, and is so closely ap-
plied to it, as to require a careful examination to
determine the true place of its commencement.

The hepatic duct (n, fig. 165) arises by two
branches from the large lateral lobes of the
liver, which unite in the fissure or ‘ gates’ of
the gland. Two hepatic ducts have been found
in the Curassow; but these and the cystic
duct terminate separately in the duodenum.

The place of termination of the cystic and
hepatic duct is generally, as shown in fig. 163
and 165, pretty close together at the end of
the fold of the duodenum ; but in the Ostrich
one of the hepatic ducts, which is. very large
and short, terminates in the commencement of
the duodenum about an inch from the pylorus;
while the other enters with the pancreatic duct
at the termination of the duodenum.

Both the cystic and hepatic ducts undergo
a slight thickening in their coats just before
their termination; and it is remarkable that,
in some of the Marsupiata, as the Kangaroo,
the termination of the ductus choledochus is si-
milarly thickened and glandular. The passage
of the bile-ducts in birds through the coats
of the intestine is oblique, as in the Mam-
malia, and they terminate upon a valvular
prominence of the lining membrane of the gut.

The Pancreas (q, 9, fig. 163, 165) consists
of two and sometimes of three distinct por-
tions in Birds; but these are so closely a
plied together at some point of their surface
as to appear like one continuous gland. It
is of a narrow, elongated, trihedral form, lodged
in the interspace of the duodenal fold, and
generally folded upon itself like the duodenum,
as in the Hornbill (fig. 165).

The structure of the pancreas is conglome-
rate, like that of the salivary glands, but the
ultimate follicles are differently disposed. In
the saliv glands these are irregularly
branched, while those of the pancreas in Birds
diverge in the same plane from digitated and
pinnatifid groups.*

The ducts (r r, fig. 163,165) formed by
the reiterated union of the efferent branches
from the component follicles of the pancreas
are in general two in number, which terminate
separately in close proximity to the hepatic
and cystic ducts; but occasionally there are
three pancreatic ducts, as in the common Fowl,
Pigeon, Raven, and Horn-bill; in which case
the third duct commonly terminates at a dis-
tance from the other two: in the Horn-bill
it proceeds from an enlarged lobe of the pan-

* Miller de Gland. Struct. Pen, fol. p. 66,

327

creas at the end of the duodenal fold, and
entering that part, as at 7’, fig. 165.

The Spleen (s, s, fig. 163, 165) is compara-
tively of small size in Birds; it is generally of
a round or oval figure, but sometimes presents
an elongated and vermiform shape, as in the
Sea-Gull, or is broad and flat as in the Cor-
morant. It is situated beneath the liver,
on the right side of the proventriculus. It
is, however, somewhat loosely connected to
the surrounding parts, so that its position has
been differently described by different authors.
We have generally been able to trace a pro-
cess of the pancreas passing into close contact
with it, and connected to it by a continuation
of vessels, as in the Horn-bill (fig. 165, q, s),
where it has been turned aside to show the

hepatic and pancreatic ducts. The texture of

the spleen is much closer in Birds than in
Mammalia; but a minute examination proves
that the blood of the splenic artery is ulti-
mately deposited in cells, from which the
splenic veins arise. These veins in the Swan
and some other Lamellirostres form a network
on the exterior surface of the spleen, as in the
Chelonian Reptiles.

Absorbents—The presumed absence of ab-
sorbent vessels in the Oviparous Vertebrata was
cited by the supporters of the theory of venous
absorption in the time of William Hunter as
strong evidence in favour of their views; and
the same assertion has again been repeated in
the present day by Majendie,* who, in sub-
sequently admitting} the existence of lympha-
tics in Birds, still contends against their being
the exclusive instruments of the function of
absorption.

Traces of the lymphatic system in the pre-
sent class appear to have been observed by
Swammerdam{ as early as 1676, who sent
his preparation ‘ Lymphaticum peculiare ex ab-
domine Galline’ to the Royal Society of Lon-
don; the lacteals were afterwards noticed in
the Stork by Jacobeus§ in 1677, and traces
of lymphatics are described by Lang|| in 1704,
and by Martin Lister{[ in 1711. Lymphatic
vessels and glands, however, considered as
such, according to the Hunterian doctrine of
absorption, were first undoubtedly seen by John
Hunter in the neck of a Swan, and the lac-
teals of Birds were afterwards re-discovered by
Hewson, who made the first attempt to give
a detailed account of the absorbent system in
Birds. Our knowledge of this system has
since been greatly enlarged by the labours
of Tiedemann,** Fohmann,t+ Lauth,{{ and
Panizza.§§

* Journal de Physiol. tom. i. p. 47.
t Annales des Sciences Nat. iii. p. 410.
t Birch, Hist. of the Royal Society, iii. p. 312.
Anat. Ciconie in Acta Hafn. v. p. 247.
Serene Lips. fol. p. 99.
Dissertatio de Humoribus, 1711, 8vo. p. 228.
** Anat. und Naturgeschichte der Vogel, tom. i.

: tt Anat, Untersuchungen tiber die Verbindung
der Saugadern mit den Venen, 1821, p. 136.
tt Annales des Sciences Nat. iii. p. 381.

$$ Osservazione Antropo-Zootomico Fisiologiche,
fol. Pavia, 1830.

328 AVES.

The species in which the absorbent system
has been investigated are the Buzzard,
pecker, Turkey, Common Fowl, Bittern, He-
ron, Stork, Duck, Swan, Wild and Tame
Goose, but especially in the latter.

The absorbents of Birds difler from those
of Mammals in having fewer valves, which
are also less perfect, being so loose as fre-
quently to permit for a certain extent a retro-
grade passage of the injected fluid. The lacteals,
lymphatics, and thoracic ducts have very thin
parietes, so as easily to be ruptured, but they
are composed, as in Mammals, of two tunies,
of which the internal is the weakest.

The lymph resembles that of Mammals,
but the chyle differs essentially in its trans-
et and want of colour. The lacteals

ave, however, been observed to contain an
opake white fluid in a Woodpecker that had
been killed after swallowing a quantity of ants.

With respect to the disposition of the ab-
sorbents, they do not form in Birds two strata,
as in Mammals; at least those only have been
observed which correspond to the deep-seated
absorbents which accompany the large vessels.

The lymphatic glands or ganglions are also
much less numerous in Birds than Mammals,
being in the former generally restricted in their
position to the anterior part of the chest or the
root of the neck. In the Penguin, however, a
femoral and two axillary absorbent glands have
recently been described.* They have the same
structure asin Man, butare softer. In other parts
of the body the absorbent glands are replaced
by plexuses of lymphatic vessels surrounding
the principal bloodvessels. It frequently hap-
pens, as in Mammalia, that two large absor-
bents form by their union a trunk, which is
of smaller diameter than either of the vessels
composing it.

The absorbents of Birds terminate principally
by two thoracie ducts, one on either side, which
enter the: jugular veins by several orifices. But
besides these communications, Tiedemann,
Fohman, Lauth, and Lippi state that the lym-
phatic plexuses of the posterior part of the
body communicate with the contiguous sacral
and renal veins. And Lauth describes several
intercommunications in other parts of the body;
these, however, are denied by Panizza, whose
careful and elaborate researches seem to prove
that the passage of the lymph into the venous
system takes place in Birds only in two places
in the pelvic region in addition to those by the
two thoracic ducts in the neck.

The lymphatics of the foot unite to form
the vessels which are found running along the
sides of each toe (1, 1, fg. 166). In the Pal-
mipedes there are anastomosing branches which
pass from the lateral vessel of one toe to that
of the adjoining toe, forming arches in the
uniting web (2). These branches form a small
plexus (3) at the anterior part of the digito-
metatarsal joint, from which three or four
lymphatics are continued. The anterior and
internal branches (4) accompany the blood-
vessels, and form a network around them;
the posterior and external branches (5) receive

* Reid, in Proceedings of Zool. Soc, Sept. 1835.

ood-.

_Absorbents of a Goose.*

the lymphatics of the sole of the foot, then
ascend along the metatarsus, and form at its
proximal articulation a close network (6); all
the vessels then ascend the tibia, forming a
plexus (7) around it as far as the middle of the

leg; then they unite into two branches, of

which the smaller passes along the anterior
part of the depression between the tibia and
fibula as far as the knee-joint, where it joins
the other branch which accompanies the blood-

vessels. The trunk formed by the union of

the two preceding branches accompanies the

femoral vessels, forming plexuses in its course”

* From Lauth’s Monograph, Annales des Sciences
Nat. t. iii. pls. 23 and 25,

AVES.

(8), which receive tributary absorbents from the
surrounding muscles, and a large branch (9)
corresponding to the deep-seated femoral vessels.

The iliac trunk (10) accompanies the great
femoral vein into the abdomen, which it enters
anterior to the origin of the pubis; it there
receives branches from the lateral parts of
the pelvis (11) and afterwards separates into
two divisions.

The posterior division receives some lym-
phatics Si the anterior lobes of the kidneys,
and those of the ovary or testicles; it com-
municates anteriorly with a branch from the
absorbents which surround the great.mesenteric
artery, and posteriorly with large vesicular
plexuses or receptacles (12, 13) surrounding
the aorta and its branches, and which receives
the lymphatics from the renal plexus, and those
accompanying the arteria sacra media (14).

The sacral or pelvic plexiform vesicles of
the lymph are described by Panizza in the
Goose as being two in number, situated in the

sterior region of the body, in the angle
setween the tail and the thigh. Fach vesicle
is little more than half an inch long and a
quarter of an inch broad, and is shaped some-
what like a kidney-bean. Panizza laid them
bare in several living Geese and punctured
them, upon which the lymph issued in con-
siderable quantity, and coagulated into a jelly
like the lymph from ordinary lymphatics.
Fluids thrown into the lymphatics leading to
the vesicles not only filled these cavities, but
passed from them into the veins. There are
analogous vesicles in the Reptiles, which are
endowed with a pulsatile power, and propel
their contents into the pelvic veins per saltum ;
but the recent researches of Miller (Archiv.
fiir Physiol. 1834, p. 300) show that the pelvic
lymphatic vesicles of Birds are not endowed
with a power of motion like that belonging to
those of Reptiles, he having satisfied himself,
by repeated examination of the living Goose,
that the alternate contraction and dilatation of
these vesicles in this animal, which Panizza
conceived to depend on an automatic power
within them, corresponds exactly with the
motions of respiration, and no longer continues
when they are interrupted.*

The anterior division of the femoral lym-
phatic trunk (16) accompanies the aorta, upon
which it forms a plexus with the branch of
the opposite side, and with the intestinal ab-
sorbents (15).

These vessels, which from the transparency
of their contents can scarcely be termed with

ropriety ‘ lacteals,’ commence from a plexi-
orm continuous network situated between the
mucous and muscular coats of the intestine;
they are larger here than when they quit the
intestine to pass upon the mesentery. They
accompany the branches of the superior mesen-
teric artery, there being many absorbents for
one artery, which by their anastomoses form
plexuses surrounding the bloodvessels. Before
reaching the aorta, these absorbents commu-
nicate with the inferior or posterior division of

* See Allen Thompson, in Edinb. Med. and
Surg. Journ. No. 125.

329

the femoral trunk, and with the absorbents of
the ovary or testicles, after which they pass
upon the aorta (16, 17), where they receive
the lymphatics of the pancreas and duodenum,
and terminate by uniting around the cceliac
axis (18) with the lymphatics of the liver, the
proventriculus (c), the gizzard, and the spleen,
forming a considerable plexus, from which,
according to Lauth, it 1s by no means rare
to see branches passing to terminate in the
surrounding veins.

The aortic plexus (19), which may be
regarded as analogous to the receptaculum
ehyli, always gives origin to two thoracic
ducts (20, 20) of varying calibre, but often,
as in the Goose, exceeding a line in diameter.
They are situated at their origin behind the ceso-
phagus (a) and in front of the aorta (6); they
advance forwards, diverging slightly from each
other, pass over the lungs (ww), from whieh they
receive some lymphatics, and terminate seve-
rally, after being joined by the lymphatics of
the wing, in the jugular vein of the same side.
The left thoracic duct, before entering the vein,
receives the trunk of the lymphatics of the left
side of the neck; the right thoracic duct re-
ceives only a branch of those of the same side.

The lymphatics. of the wing follow the
course of the brachial artery, forming a plexus
around it, especially at the elbow-joint. Their
pesca trunk, to which all the collateral

ranches are united about the upper third of
the humerus, is here of large size, but its di-
ameter soon begins to be diminished, and it is
very small at the head of the humerus. When
it reaches the parietes of the chest, it receives
two or three large lymphatics from the pectoral
muscles, and a branch which accompanies the
brachial plexus. Soon after a small lym-
phatic gland is sometimes formed on the trunk,
which lastly unites with the thoracic duct of
its own side.

The lymphatics of the head accompany. the
branches of the jugular vein, and are readily dis-
cerned upon those whichare situated between the
rami of thelower jaw. They form, by uniting with
the cervical absorbents, two lateral branches on
each side, which accompany the corresponding
jugular vein, being situated, one in front, the
other behind that vessel. These lymphatics
communicate together, at the anterior and pos-
terior parts of the neck, by transverse or ob-
lique branches. They receive in their progress
absorbents from the muscles, and from the
peculiar glands which are seen beneath the
skin of the neck. The internal branch on the
left side receives also a considerable absorbent
from the cesophagus. At the lower part of the
neck both branches receive a notable branch
which accompanies the carotid arteries, and
a little further on they form on each side a
lymphatic gland situated on the jugular vein.
On the right side the trunk of the cervical
lymphatics terminates in the jugular vein, after
having furnished a communicating branch with
the thoracic canal of that side; on the left side
it terminates at once in the corresponding tho-
racic duct.

Vascular system. — Heart.—The heart in
Birds is divided, as in Mammals, into four

330

distinct cavities, which have the same relations
to each other, and impress the same course
on the circulating fluid.*

The form of this viscus is always that of a
cone, sometimes wide and short, as in the
Ostrich and Crane; sometimes more elongated,
as in the Emeu (fig. 167) and Vulture; or
still more acute, as in the Curlew, Common
Fowl, &c.

Its situation is more anterior and mesial than
in Mammalia, and its axis is always parallel
with the axis of the trunk. It is not contained
with the lungs in an especial cavity, but its
apex is lodged between the lobes of the liver ;
the diaphragm not being so far developed as
to separate the chest from the abdomen.

As the lungs are confined to the dorsal part

of the chest, the whole of the anterior surface .

of the pericardium is exposed when tke sternum
of the bird is removed. The pericardium is thin,
but of a firm texture, and adheres by its ex-
ternal surface to the surrounding air-cells. It
is of considerable size, and commonly prolonged
for some way between the lobes of the liver.
The auricles of the heart in Birds have not
externally such distinct appendices as in Mam-
mals. The right auricle is much larger than
the left; it is more distinctly divided internally
into a sinus (d, fig. 167) and auricle proper

Fig. 167.

\ }
ng

Heart of the Emeu.

than in Mammals, and these parts are separated
by a more complete valvular structure; in which
respect Birds bear a closer analogy to Reptiles.

Three veins terminate in the sinus, there
being in Birds always two superior cave,
as in Reptiles. The right superior cava (a),
which returns the blood from the right wing
and right side of the neck, terminates in
the upper and anterior part of the sinus; the
left superior cava (b, b) winds round the pos-
terior part of the left auricle to open into the

* The blood of Birds differs from that of the
other Vertebrate classes in the greater number of
globules, and from that of Mammalia in their
form, which is oval instead of round. Sce BLoop.

AVES.

lower part of the sinus; just beforeits termination
it receives the coronary vein, so that this does
not open separately into the auricle as in most
Mammalia.* The inferior cava (c) terminates
in the sinus just above the orifice of the left su-
perior cava, and a semilunar valvular fold (h),
analogous to that of the coronary vein in man,
is extended forwards between these orifices so
as to separate them, and afford a protection to
the mouth of the left superior cava, in addition
to that which it derives in common with the
other veins from the larger valves at the mouth
of the sinus.

The disposition of the valves between the
sinus and auricle seems more especially des
tined to prevent regurgitation into the sinus,
when the pulmonary circulation may be im-
peded, rather than to impress any definite
course on the current of blood flowing through
the auricle, as Cuvier supposes. A sirong
oblique semilunar muscular fold (g) commences
in the Emeu by a band of muscular fibres
running along the upper part of the auricle,
and expanding into a valvular form extends
along the posterior and left side of the sinus,
terminating at the lower part of the fossa ovalis
(z). A second semilunar muscular valve (/),
of equal size, extends parallel with the preceding
along the anterior border of the orifice of the
sinus, its lower extremity being fixed to the
smooth floor of the auricle, its upper extremity
being continued into a strong muscular column
running parallel to the one first mentioned
across the upper and anterior part of the
auricle, and giving off from its sides the greater
part of the musculi pectinati. From this strue-
ture it results that the more powerfully the
musculi pectinati act in overcoming the ob-
stacle to the passage of the blood from the
auricle to the ventricle, the closer will the valves
be drawn together, and the stronger will be
the resistance made by them to the regurgitation
of the blood from the auricle into the sinus.
The parietes of the auricle in the interspaces of
the muscular fasciculi are thin and transparent,
consisting in many parts only of the lining mem-
brane of the cavity and the reflected layer of the

ericardium blended together. The fossa ovalis

t) is a deep depression situated behind the pos-
terior semilunar valve, which, we may observe,
bears nearly the same relation to the fossa as
the annulus ovalis in the human heart. The
membranous septum closing the foramen ovale
is complete and strong, but thin and semi-
transparent. The appendix auricule (x) is the
most muscular part of the cavity; it does not
project freely in front of the great vessels
arising from the ventricles, but is tightly tied
down to them by the reflected layer of the

ericardium. The auriculo-ventricular orifice
is an oblique slit (k, fig. 169; a bristle is passed
through it in fig. 167). The manner in which re-

* In those Mammalia which approach nearest to
the oviparous vertebrata, as the Monotremata and
Marsupiata, there are always two superior cave, as
in Birds and Reptiles; a similar structure obtains
in some of the Rodentia, as the Porcupine; and
also occurs in the Elephant. In all these cases we
have found that the coronary vein terminates in
the left superior cava.

AVES.

gurgitation by this orifice is prevented is one
of the chief peculiarities in the heart of Birds.

Ventricles of the heart of a Swan.

The right ventricle (k, fig. 168) is a narrow trian-
gular cavity, applied as it were to the right and
anterior side of the left ventricle, but not ex-
tending to the apex of the heart. The parietes
are smooth, and, except at the septum ventri-
culorum, they are of pretty uniform thickness,
but weaker in comparison to those of the left
ventricle than in Mammalia. A number of
short fleshy columns extend from the septum
to the free parietes of the ventricle at the angle
of union of these two parts, leaving deep cells be-
tween them ; a strong fleshy column (m, fig. 169)
also extends from the right side of the base of
the pulmonary artery to the upper extremity of
the auriculo-ventricular valve; but these are
the only columne carnee in the right ventricle ;
there being none of a pyramidal form pro-
jecting into the cavity, nor any chord@ ten-
dineg. The principal valve which guards the
auricular aperture is a strong muscular fold
(/, fig. 167, 168, 169), nearly as thick as the
walls of the ventricle itself, extending from the
fleshy column above mentioned obliquely down-
wards and backwards to the angle formed be-
tween the septum cordis and the wall of the
ventricle at the lower and posterior part of the
cavity. The free rounded edge of this muscular
valve is turned towards the convex projection
made by the septum, and must be forcibly ap-
plied to this part during the systole of the
ventricles, so that, while all reflux into the
auricle is prevented, additional impulse is given
to the flow of blood through the pulmonary
artery; the muscular parietes of the ventricle
being thus complete at every part except at the
orifice of the artery.

The small muscular column (m, fig. 169) at
the upper part of the auricular orifice is analo-
gous in its position to the single valve which
guards the corresponding orifice in Reptiles ;
in which class the Crocodiles alone present a

33t
second muscular valve, which, though small, is

Fig. 169.

Section of the ventricles, Pelecan.

analogous in its position, and evidently a rudi-
mental form of the large muscular valve in
Birds. .

The right ventricle is remarkable for the
smoothness and evenness of its inner surface.
The pulmonary artery is provided at its origin
with three semicircular valves (n, fig. 169). It
divides, as usual, into two branches (7, n, fig.
168), one for each lung ; the right branch passes
under the arch of the aorta.

The aerated blood is returned from the lungs
by two veins which open into the back part
of the left auricle; a strong semilunar ridge,
which is hardly sufficiently produced to be
called a valve, divides the cavity of the auricle
in which the veins terminate from the mus-
cular part or appendix. The fleshy columns
are very numerous and complicated in this part
of the auricle, which is closely tied down to
the ventricle by the serous layer of the pericar-
dium and dense cellular tissue.

The left ventricle (0, fig. 168, 169) is an elon-
gated conical cavity, the parietes of which are
three times as thick as those of the right ventricle,
and exhibit strong fleshy columns extending from
the apex towards the base; two of the largest
of these columns present in the Emeu a short
convex eminence towards the auriculo-ventri-
cular orifice (r, fig.169), and give off short thick
tendons to the margin and ventricular surface
of two membranous folds, (p, q, fig. 168, 169)
which correspond to the mitral valve in Mam-
malia. Of these valves, the one next the aorta(q)
corresponds to the single valve which guards
the auricular opening in the heart of Reptiles,
and is most developed in Birds; the oppo-
site valve is of much less size. In many Birds
the chorde tendinee pass from the valves at
once to the parietes of the ventricle, and are
not attached to columne carnee. The surface
of the ventricle formed by the septum is smooth
from the orifice of the aorta down to the apex
of the heart. The aorta is provided, as in Mam-
malia, with three semicircular valves. In Rep-
tiles, even in the Crocodile, the great arteries
arising from the ventricles are each provided
with two valves only.

We have observed that in general the valves
at the base of the pulmonary artery were
thicker and stronger than those at the origin
of the aorta, and our lamented and talented
friend Mr. Home Clift discovered some years

332

ago that the extremities of the semilunar valves
in Birds were connected to small, firm, and
sometimes ossified styles imbedded in the fibrous
coat of the vessels.

The arrangement of the muscular fibres of the
ventricle in Birds is such that the right ventricle
appears to be formed by a partial secession of
the outer from the inner layers of the parietes
of the left ventricle at the anterior and right
side of that cavity. See the transverse section,
(fig. 169.)

Arteries—The distribution of the arterial
system has been described in a general man-
ner by Cuvier, Tiedemann, and Nitzsch, and
has subsequently been very completely elu-
cidated by Barkow in the 12th Volume of
Meckel’s Archives of Physiology ; where the
different varieties which various species of birds
present in the course of individual arteries
are laboriously pointed out. In our own dis-
sections we have been guided by the excellent
description long ago given by Dr. Macartney,
(Art. Birds, Rees’ Cyclopedia) which we shall
here give verbatim, with some general remarks
and additional particulars afforded by the re-
searches of Barkow and our own dissections.
The description will be aided by the subjoined.
beautiful figure taken from Barkow’s Mono-
graph (fig. 170).

The arterial system in Birds is essentially
distinguished from that of Mammals by the
following differences :—

1st.. The: division of the aorta into three
principal branches, almost immediately at its
origin.

2d. The course of the. arch. of the: aorta over
the right instead of the left bronchus, to: become
the descending aorta.

3d. The origin. of the arteries of the posterior
extremities, which do not come off from a single
branch analogous to the external iliac of Mam-
malia, but from two arteries which are detached
successively from the aorta at a great distance
from. each other, and pass.from the pelvis by
two separate apertures.

The arteries of the systemic circulation
proceed, Macartney observes, “from a single
trunk, which arises from the left ventricle of
the heart. This. trunk, the aorta, (1, fig. 170)
is so short that it is concealed by the other
pots on the: basis of the heart, and is only

rought into view after the reflections of the
pericardium. and the adjoining vessels are de-
tached by dissection. It is from thence that
as the parts are commonly beheld, there appear
to be.three great arteries issuing together from.
the middle of the heart, which are the primary
branches into which the aorta is divided. The
first branch is to the left side, and after it is
sent off, the trunk affects to turn over the au-
ricle before it gives the branch of the right
side; these two branches in a curved
manner from the heart towards the axilla in
the form of horns, and each is analogous to
the arteria innominata of the human subject,
so that instead of one there may be reckoned
two arterie innominate in Birds (¢ t, fig. 167,
168). After these branches are parted with, the
arterial trunk (s, fig. 167, 168, 2, fig. 170) is
continued over the auricles,” and the right bron-

AVES.

Fig. 170.
E
13
12
F
10
ll YZ ll
if
G-- 4
8 ae
7
4
5
5 -84
? -S15
7 16 %
4 3
44
i9-F . 1
2 Z o -17
4 18
17
20
21
22 (
23 y N
26 - 29
)
\ 25 = 30
18 \ # 18
as | { 31
32
Sauna, j

»

Arteries of the Trunk, Grebe.

chus, “and, on reaching the back part of the
heart, becomes the descending aorta.

“The arteria innominata (3) first sends off
the common trunk of the carotid and vertebral
arteries (4), which before its divisien gives, off
one or two small branches ; one of these runs
down upon the lungs in company with the par
vagum, and appears to supply branches to the
aponeurosis of the lungs, and the air-cells at
the upper part of the thorax; the other branch,
after supplying the lymphatic gland of the
neck with several small arteries, ascends upon
the.side of the esophagus, to which, and the
inferior larynx, the divisions of the trachea,
and to the parts and integuments of the side of
the neck, its branches are distributed, anasto-
mosing with the superior csophageal and tra-
cheal arteries. This branch is often not sent
off until the trunk divides into the vertebral and
carotid, in which ease it comes from the latter
artery. Sometimes in the Duck, the supra-
scapular artery, which is usually divided from
the vertebral, is a branch of the common trunk.”

The carotid arteries (4, 4, fig. 170, w u, fig.
167) are frequently of unequal size; in the Dab-
chick the left is by much the largest; in the
Emeu we found it the smallest. “In the Com-
mon Fowl, each carotid, after parting from the
vertebral artery (6), proceeds to the middle of the
neck and soon disappears ; becoming covered by
the muscles of the anterior part of the neck, and
entering the canal formed by. the inferior spinous

AVES.

processes of the cervical vertebra, within which
it lies hidden, and in close contact with its fellow
of the other side, to very near the head.” In
the Bittern the two carotids are situated one
behind the other, and adhere so intimately to-
gether in this situation that they have been
erroneously described as a single trunk.

“ The carotid artery emerges from between
the muscles of the neck, at about the third or
fourth vertebra from the head (9); and after
giving a branch (10,11), Arterie cutanee colli
laterales, downwards, to the lateral muscles and
integuments of the neck, it runs along the outer
edge of the rectus major anticus muscleto behind
the angle of the jaw, where it divides into its
several branches.

“ An artery (arteria oceipitalis) first goes off
posteriorly, which passes a little forwards under
the branch of the os hyoides, and after sending
some blood to the muscles of the neck, makes
a turn backwards, enters the foramen in the
transverse process of the second vertebra, and
terminates by a singular anastomosis in the
vertebral artery.*

“ The next branch is analogous to the internal
carotid; it goes forward also under the os
hyoides, and passes behind the muscles of the
jaws close upon the lower part of the skull, at
which place it sends a branch upwards, which
appears to penetrate the bones on the outside
of the ear, and supply the organ of hearing,
sends a branch into the skull and another
through the articulation of the jaw, to unite
with the ophthalmic, and contribute to the
plexus at the back of the orbit (Rete oph-
thalmicum of Barkow). The internal carotid
then enters an osseous canal, which runs
along the basis of the cranium, between the
tables of the bone; and at the lower and
back part of the orbit, the artery receives a
remarkable anastomosing branch of the inter-
nal maxillary, which almost equals in size the
carotid itself, and these two vessels produce
by their union one which passes almost directly
into the cranium at the usual place for the
entrance of the carotid artery. This vessel
forms within the skull an anastomosis similar
to the circle of Willis; but the branch which
oceupies the place of the basilar artery is very
pane and appears to be furnished entirely
from the anastomosis of the carotids, and de-
signed only to supply the medulla oblongata
and spinal marrow. The branches of the in-
ternal carotid are thickly spread in an arborescent
form upon the surfaces of the brain; some on
the outside and others on the internal super-
ficies of the ventricles, and the fissure between
the two hemis -” Theorbital plexus formed
by the carotid sends off the inferior palpebral,
ethmoidal, lachrymal, and ophthalmic arteries.
The ophthalmic artery forms two remarkable
plexuses at the posterior part of the globe of the

* Dr. Barkow has subsequently established the
accuracy of this observation, having found this
singular anastomosis of the occipital with the ver-
tebral artery in all the birds which he has injected.
Tiedemann is therefore inaccurate in saying that the
vertebral artery has the same termination in birds
as in man.

333

eye; the first is situated close beside the inner
side of the optic nerve, and is formed by am
artery analogous to the arteria centralis retine,
and gives off the artery to the base of the
marsupial membrane; the second plexus is
situated more exteriorly, and gives off the ciliary
arteries.

* After the trunk of the carotid has sent off the
internal carotid, it passes for a little way down-
wards and forwards behind the angle of the jaw,
and divides at once into different branches, cor-
responding to those of the external carotid in
mammalia; the first of which might be called
the cesophageal or laryngeal artery. This vessel
sends a branch to the muscles upon the horn
of the os hyoides, and then turns downwards
and divides into two branches, one to the
trachea (G, fig. 170), and the other to the ceso-
phagus, upon the side of which parts they
descend to near the thorax,” forming a series of
arches (11, 11), and ultimately inosculate with
the tracheal and cesophageal branches of the
common trunk of the carotid and vertebral
arteries.

‘“‘ The external maxillary artery (12) dips in
between the pterygoid muscle and that which is
situated at the back of the lower jaw for open-
ing the mouth; it then passes behind the
tympanic bone, and gives twigs upwards to the
muscles of the jaws, and to the plexus at the
back of the orbit: upon emerging from behind
the tympanic bone, it lies under the zygo-
matic or jugal bone, and sends an artery up-
wards, which is distributed to the temporal
and masseter muscles, and proceeding under
the triangular tendon that comes from the
inferior margin of the orbit to the lower jaw,
it divides into two principal branches; one of
these passes along the side of the upper jaw,
gives a branch upwards to the fore part of the
orbit which unites with the ophthalmic artery,
and is lost at the top of the head. This branch
is very large in birds with combs, as in con-
junction with the ophthalmic, it furnishes
numerous vessels to these vascular parts. The
artery then goes on and supplies branches to
the sides of the head before the orbits, and to
the integuments and substance of the upper
mandible, inosculating with the palatine branches
of the internal maxillary artery. The second
portion of the external maxillary proceeds to
the lower jaw, to which, and the lower part of
the masseter muscle, it is distributed. The
external maxillary supplies the place of the
temporal, labial, angular, nasal, and mental
arteries of mammalia.

“ The Jaryngeal or posterior palatine artery is
a little branch of the external carotid, which
is sent off posteriorly opposite to the external
maxillary artery. Its branches are exhausted
upon the back part of the fauces, the mus-
cles for moving the upper jaw, and posterior
nares.

“ The lingual or submaxillary artery (13)
passes under the muscles which connect the os
hyoides to the lower jaw, and close upon the back
of the membrane of the lower part of the mouth,
it sends a branch to the cesophagus and trachea,
supplies the musc'es of the os hyoides ( F'),

334

the tongue (H, fig.170), the lower surface
of the mouth, and furnishes the artery which
enters the substance of the lower jaw.

~ © Just at the origin of the submaxillary arter
there is another little branch of the cunt
which is lost upon the muscles of the os
hyoides.

“ The internal mavillary artery is, as usual,
the continuation of the trunk of the external ca-
rotid; it runs forwards between the pterygoid
muscle, and the lining of the mouth, upon the
side of the long muscle for moving the upper
jaw, and divides into two principal branches ;
one of them proceeds under the tendon of the
long muscle to get upon the palate, where it
forms two branches, of which one runs along
the external side of the palate, between the
membrane and the bone of the mandible to
the extremity of the bill, where it becomes
united to the same branch of the opposite side,
as also to the middle artery of the palate. The
other branch lies also superficially under the
membrane which lines the mouth. It passes
onwards to meet its corresponding vessel of
the opposite side, with which it becomes ac-
tually incorporated, and by their union a single
artery is generated, which runs along the mid-
dle line of the palate to the end of the mandi-
ble, where it unites with the lateral branches,
as already mentioned. At the junction of the
vessel of each side to form the middle pala-
tine artery, two branches go off, which are lost
upon the lining of the mouth, and the interior
of the organ of smell.

“ The other branch of the internal maxillary
artery is reflected upwards towards the orbit,
below which it divides and unites again, form-
ing a triangle, through which the vein passes :
at this place it produces a remarkable plexus
of vessels, like the rete mirabile of the carotid
artery of quadrupeds, which is increased by
branches from the ophthalmic and the palatine
arteries, and from which the back part of the
organ of smell receives its supply of blood.

“The internal maxillary artery then runs direct-
ly backwards below the orbit, passes between the
radiated or fan-shaped muscle which moves
the upper jaw and the pterygoid process; and
turning inwards round the basis of the cranium,
becomes incorporated with the internal carotid
artery just as it enters the bony canal which
conducts it to the brain.*

“The vertebral artery (6), soon after it parts
from the carotid, sends off a branch backwards,
which passes over the neck of the scapula and
is lost among the muscles on the posterior part
of the shoulder, inosculating with the articular
and other arteries about the joint: this branch
might be called the supra-scapular (5). In the
duck we have observed it, before it makes the turn
over the scapula, to send an artery upwards
along the muscles of the neck. The trunk of
the vertebral artery proceeds obliquely upwards,

* Barkow describes the internal maxillary artery
as wanting in birds, and its place being supplied by
branches of both the external and internal carotids
and the facial artery, all of which sometimes unite
to form the maxillary plexus of vessels, which is
very conspicuous in the Goose and Duck.

AVES.

and having entered the foramen in the transverse
process of the second cervical vertebra, gives off
a large branch downwards, which is distributed
between the vertebrae, and to the spinal canal,
in the manner of the intercostal arteries, with
which it anastomoses upon arriving in the
thorax. The remainder of the vertebral artery
is continued upwards in the canal formed in
the transverse processes of the cervical vertebra,
diminishing gradually in consequence of the
branches it sends off between each vertebra to
the spinal marrow and the muscles of the neck.
Near the head the artery is found considerably
reduced, and within the last foramen in the
transverse processes terminates entirely by
inosculation with the reflected occipital branch
of the carotid, as before noticed.

“ The extraordinary anastomoses and the
plexuses which are to be observed in the arte-
ries of the head in birds are not easily ac-
counted for. It seems possible that they may
be required in consequence of the great length
of the neck in these animals, it being well
known that frequent communication amongst
the vessels, although it diminishes the impetus
of the circulation, ensures a free and uninter-
rupted motion of the blood. ;

“< After the common trunk of the carotid and
vertebral is detached from the arteria innominata,
this vessel may assume the name of the sub-
clavian (14). While passing under the clavicle
it sends off some important branches: the first
might be called the pectoral artery ; it proceeds
upwards upon the internal surface of the pec-
toralis minimus muscle, which it supplies, and
then dividing into two branches, one passes
over the anterior edge of the clavicle, and under
the pectoralis medius, between which and the
sternum it runs, detaching its branches to the
muscle; the other sends first along the under
side of the clavicle a branch which is again
subdivided and distributed to the outside of
the shoulder-joint and to the deltoid muscle;
in which it inosculates with the articular artery.
The vessel then passes between the clavicle
and the fork-shaped bone, and ona ligament
which connects the head of the clavicle to that
of the scapula, and disperses its branches
upon the upper part of the shoulder-joint, form-
ing anastomoses with the neighbouring arteries.

“The next branch of the subclavian is the
humeral artery (15); it arises from the upper
side of the vessel, and makes a slight curve
to reach its situation on the inside of the arm
in order to disperse its branches in the manner
hereafter described.

“ The internal mammary artery (24, fig. 171)
is given off just as the subclavian leaves the
chest. It divides into three branches; one
ramifies upon the inner surface of the sternum,
another upon the sternal ribs and the inter-
costal muscles, and the third runs along the
anterior extremities of the vertebral ribs, sup-
plying the intercostal muscles, &c.

* The chief peculiarity of the arteries of the
superior extremities in birds consists in the
great magnitude of the vessels which supply
the pectoral muscles; these, instead of being
inconsiderable branches of the axillary artery,

AVES.

are the continuations of the trunk of the sub-
clavian, of which the humeral is only a branch.

“ The great pectoral or thoracic artery passes
out of the chest over the first rib and close to
the sternum, and immediately divides into two
branches. One of them (16) ramifies in the
superior part of the pectoralis major, and the
other (17) is exhausted in the lower part of the
muscle, and sends off a branch analogous to
the long thoracic artery of mammalia.” Nos. 16
and 17 show the distribution of these arteries to
the skin after perforating the pectoralis muscle.

“The humeral artery, while within the axilla,
gives a small branch backwards to the muscles
under the scapula, and upon reaching the
inside of the arm produces an artery that soon
divides into the articular and the profunda
humeri. The articular artery passes round the
head of the humerus, underneath the extensors ;
its branches penetrate the deltoid muscle, and
anastomose with the other small arteries around
the joint.

“ The profunda humeri, as usual, turns under
the extensor muscles to reach the back of the
bone, at which place, in birds, it separates into
two branches, of which one descends upon the
inside, and the other upon the outside of the
articulation of the humerus with the radius and
ulna, and there inosculate with the recurrent
branches of the arteries of the fore-arm.

“ After the humeral artery has sent off the pro-
funda, it descends along the inner edge of the
biceps muscle, detaching some branches to the
neighbouring parts: upon arriving at the fold
of the wing, it divides into two branches; one
of these is analogous to the ulnar artery, and
the other from its position deserves to be called
rather the interosseous than the radial artery.

“ At the place where the humeral produces
the two arteries of the fore-arm, a small branch is
sent off, which is lost upon the fore-part of the
joint, and in anastomoses with the recurrent of
the ulna and profunda humeri.

“ The ulnar artery is the principal division of
the humeral ; it proceeds superficially over the
muscles which are analogous’ to the pronator,
sends a large recurrent branch under the flexor
ulnaris to the back of the joint, upon which it
ramifies and forms anastomoses with the pro-
funda humeri. The artery then proceeds along
the imner edge of the ulnar muscles, to which
it distributes branches. Jt is afterwards seen
passing over the carpal bone of the ulnar side,
and under the annular ligament, at which place
it sends off some branches which spread upon
the joint and inosculate with the similar ones
of the interosseous artery. Very soon after the
ulnar artery gets upon the metacarpus, it dips
in between the bones, and re-appears upon the
opposite side, lying under the roots of the
quills, to each of which it sends an artery ; it
preserves this situation to the end of the meta-
carpal bones, where it passes between the style
analogous to the little bogus and the principal
or fore-finger, and pursues its course along the
edge of the latter, to the extremity of the wing,
supplying each of the true quills with an artery,
and sending at each joint of the finger a cross

335

branch to communicate with the anastomosing
branches on the opposite side.

“The interosseous artery detaches firsta branch
of some size to the membrane which is spread in
the fold of the wing, upon which it forms several
ramitications. (See 0, fig. 171.) After this the
artery dips down behind the pronator muscles to
get into the space between the ulna and radius.
It here gives a branch backwards to communi-
cate with the others about the joint, and pro-
ceeds in the interosseous space as far as the
carpal joint, during which course they become
much diminished from giving off several
branches which are distributed to the integu-
ments and the quills placed upon the outside
of the ulna. The remainder of the interosseous
artery is expended in small branches upon the
back of the carpal joint, the bastard quills, and
along the radial edge of the metacarpus and
bones: of the fore-finger, where it forms com-
munications with the cross branches of the
ulnar artery already mentioned.

“From this description it will be perceived
that no artery exists in birds strictly analogous
to the radial; that there are no palmar arches ;
and that the size of the interosseous artery, and
the course of the ulnar, along the outside of the
metacarpus, are peculiarities which arise from
the necessity of affording a large supply of
blood to the quills during their growth.

“ The descending aorta (19, fig. 170) makes
a curve round the right auricle and right
bronchus, in order to get upon the posterior
surface of the heart, after which its course
is close along the spine, in which situation it
is bound down by cellular substance, and the
strong membrane or aponeurosis, which covers
the lungs on their anterior part. The first
branches which this vessel appears to send off
are bronchial arteries ; they arise from the fore
part of the aorta, just when it arrives upon the
spine; and having entered the lungs, their ra-
mifications accompany those of the pulmonary
arteries. They appear also to send branches to
the spine and the spaces between the ribs.

“The intercostal arteries do not take their
origin from the aorta in numerous and regular
branches as in mammalia, but consist originally
of but few vessels, which are multiplied by
anastomoses with each other, and with the
arteries which come out of the spinal canal.
An arterial plexus is thus formed round the
heads of the ribs, from which a vessel is sent
to each of the intercostal spaces. Many of
these branches, besides supplying the intercos-
tal muscles and ribs, are continued into the
muscles upon the outside of the body and the
integuments. The anastomosis of the inter-
costal arteries round the ribs is very similar to
the plexus, which is produced by the great
sympathetic nerve in the same situation.

“ The aorta produces no branch which de-
serves the name of the phrenic artery, as birds
do not possess that muscular septum of the
body to which the artery of this name is dis-
tributed in other animals.

“The caliac artery (20, fig. 170) isa very large
single trunk, and arises from the fore part of the

936 AVES.

aorta, even higher than the zone of the gastric
glands. It descends obliquely for a short way,
and then gives off a branch which soon divides
into two or three others that are spread upon
the lower part of the cesophagus, and the side
of the zone of the gastric glands, uniting with
the other arteries of the esophagus above, and
extending downwards upon the posterior side
of the ventricle, and anastomosing with the an-
terior gastric artery. The trunk of the cceliac
now divides into two very large branches,
which from their distribution we have chosen
to call the posterior and the anterior gastric
arteries.

“The posterior gastric artery, almost as soon
as it is formed, detaches the splenic ‘artery ;
and very soon after it furnishes from the poste-
rior side of the vessel the right hepatic artery,
This branch proceeds to the right lobe of the
liver, which it enters on the side of the hepatic
duct; after having divided into two or three
minute arteries on its way to the liver, it su
plies the hepatic duct with a branch which
accompanies the duct to the intestine, and is
there lost. The posterior gastric artery then
runs down upon the back of the gizzard, and
opposite to the origin of the first intestine it
sends offan artery, which proceeds directly to one
of the cceca (in the Fowl), upon whichand the side
of the next intestine it is.expended, inosculating
at the end of the coecum with branches of the
mesenteric artery, which are distributed to the
adjoining portion of the small intestine. The
posterior gastric then furnishes a large vessel
which runs upon the gizzard, and divides into
two chief branches, which penetrate the sub-
stance of the digastric muscle, in which they
are lost.

“The next branch of the posterior gastric
artery is the pancreatic. It runs between the
two pancreatic glands, dispensing branches to
each and to the duodenum. After this the
trunk of the posterior gastric divides into two
branches, which furnish twigs to the muscular
parietes of the ventricle, and run along the
margins of the upper and lower portions of the
digastric muscle. Supplying them with nume-
rous twigs, and anastomosing with the ramifi-
cations of the other gastric arteries.

“ The anterior gastric artery descends to the
angle formed by the bulbus glandulosus and
the gizzard, and there sends off a small branch
which spreads upon the zone of the gastric
glands, and inosculates with the first ramifica-
tions of the celiac, and immediately afterwards
it detaches a large artery, which runs round the
superior margin of the digastric muscle, which
it furnishes with many twigs, and communi-
cates freely with the corresponding branch of
the posterior gastric artery.

“ Three small hepatic arteries take their
origin from this branch of the anterior gastric,
just as it passes over the highest part of the
margin of the gizzard; these vessels enter the
fissure in the left lobe of the liver. The ante-
rior gastric artery now proceeds along the fore
part of the gizzard, sending one or two branches
into the muscular substance, and near the ten-

don it terminates in two large one of
which is distributed upon the left side of the
digastric muscle, and the other passes a little
over the tendon, and then divides into two
arteries, which produce several branches that
disappear in the substance of the gizzard, and
between the digastric muscles and the parietes
of the ventricle, anastomosing with the vessels
of the posterior side.

“The superior mesenteric artery (21, fig. 170)
takes its origin from the fore part of the aorta, a
little below the cceliac, and proceeds for some
way without detaching any branches; after
which it experiences the same kind of division
and subdivision that takes place in mammalia,;
and the numerous arteries which are thus ulti-
mately produced are spent upon the small intes-
tines. One of the first and largest branches of
the superior mesenteric, however, is allotted to
supply one of the ceeca, and to establish a com-
munication with the inferior mesenteric and
gastric arteries. This branch, soon after it
leaves the trunk of the superior mesenteric,
divides into two. -One descends upon the rec-
tum, where it meets with the inferior mesenteric
artery, with which it produces a very remark-
able anastomosis, similar to the mesenteric arch
in the human subject; this united artery sup-
plies the rectum and origin of the ceca. The
second portion of this branch of the superior
mesenteric runs in the space between the last
part of the small intestine and the cecum of
one side, sending numerous branches to each,
and at the end of the cecum communicates in
a palpable manner with another branch of the
superior mesenteric artery, which runs upon the
adjoining part of the small intestine.

“A branch (22, Arteria spermatica) arises
from the anterior part of the aorta, just below
the lungs; it is designed for the nutrition of
the organs of generation, and except in the
season for propagation, it is so small as to
be discovered with difficulty; but when the
testicles become enlarged, it is considerably
increased in size in the male bird, and much
more so in the female, when the ovary and
oviduct are developed for producing eggs. It
nearly equals the superior mesenteric artery
during the period of laying, in which state we
shall describe it. It is a single artery, like the
celiac and mesenteric, proceeds at a right angle
from the aorta, and soon sends off a branch,
which goes into the kidney of the left side, to
which it, gives some twigs, and afterwards
emerging from the kidney, it runs in the mem-
brane of the oviduct, upon which jit is distri-
buted. After this branch is detached, the
artery projects a little farther forwards into
the cavity, and divides into two branches; one
of these goes to the ovary, in which it ramifies,
and furnishes an artery of some size to each of
the cysts containing the ova. The other is dis-
tributed in numerous branches to the mem-
brane and superior parts of the oviduct, and
inosculates with the other arteries of the
oviduct. It deserves to be remarked, that this
and all the other arteries which are furnished
to the oviduct have a tortuous or undulating

—,

AVES.

course, in the same manner as the vessels of
the uterus of the human subject. ee

“‘ There are no regular emulgent arteries in
birds; the kidneys deriving their blood from
various sources, which will be pointed out as
they occur

“ The inferior extremity is supplied with two
arteries, which have a separate origin from the
aorta. One corresponds with the femoral ar-
tery, and the other deserves the name of ischia-
dic artery.

“The femoral artery (23, fig. 170, 171) isa
small trunk, which takes its origin from the side
of the aorta, opposite to the notch in the bones of
the pelvis immediately under the last rib. This
notch is formed into a round hole in the recent
subject by a ligament which is extended from it
to the rib; and it is through this hole that the
femoral artery makes its exit from the pelvis; just
before it passes out upon the thigh, it sends off a
long branch (25), which runs backwards the
whole length of the margin of the pelvis, dis-
pensing arteries to the abdominal muscles on one
side, and the obturator internus on the other.
This branch also appears to supply one to the
oviduct. The femoral artery, immediately after
leaving the pelvis, separates into two branches ;
one goes upwards and outwards, ramifying
amongst the muscles in that situation; the
other turns downwards, and is distributed to
the flexors of the limb and round the joint, and
sends an artery to the edge of the vastus inter-
nus, which can be traced as far as the knee.
The kidneys appear to derive some irregular
inconsiderable branches from the femoral artery
while it is within the pelvis.

“The ischiadic artery (26, fig. 166, 170)
is the principal trunk of the lower extremities,
exceeding very much in size the femoral. When
it is produced by the aorta, it appears to be the
continuation of that trunk ; the remaining part
of the aorta becomes so much and so suddenly
diminished, and seems, as it were, to proceed as
a branch from the back part of the vessel.

“ The ischiadic artery, while in the pelvis, is
concealed by the kidneys, in which situation it
gives a branch from its lower side, which di-
vides into three others that are distributed to
the substance of the kidneys; one of these on
the left side is continued out of the kidney to
be lost upon the oviduct. The artery leaves
the pelvis by the ischiadic foramen in company
with the great nerve, while, within the foramen,
it gives a branch obliquely downwards under
the biceps to the muscles lying in the pelvis ;
and as it over the adductor it sends off
another along the lower edge of that muscle,
which is chiefly lost in the semi-membranosus.
It then detaches several small branches to the
muscles on the outer and fore part of the
thigh, some of which anastomose round the
joint with the branches of the femoral artery.
Just as the ischiadic arrives in the ham, it
furnishes a very large branch downwards,
which divides into two; one goes under the
gastrocnemius, to which and the deep-seated
flexors its branches are distributed as far as the
heel ; the other is analogous to the peroneal
artery ; it goes to the outside of the leg, sup-

VOL, I.

337

plies the peroneal muscles posteriorly, and
passes along the outer edge of the flexors of
the toes to the heel, above which, and behind
the flexor tendon, it divides, running on each
side of the heel, and forming several articular
arteries around the joint, and communicating
with the other branch, and with the anterior
tibial, and the metatarsal branch of the plantar
artery.

“« The articular arteries go off next from the
artery in the ham ; the two principal ones are
deep-seated. One proceeds under the vastus
internus to the external part of the joint; the
other is large, and situated upon the inside.
It forms two vessels: one is the true articular
artery, and spreads upon the ligaments of the
joint; the other is distributed in the substance
of the flexor of the heel, which is placed upon
the inside and fore part of the leg, and comes
out upon the edge of this muscle to be lost in
the integuments.

“ The posterior tibial artery (28, fig. 171)
is extremely small; it only supplies muscular
branches to the internal head of the gastrocne-
mius, and some of the flexors of the toes ; it
is lost on the inside of the heel in anastomoses
with the peroneal artery, and other small
superficial branches.

“ The trunk of the artery of the leg now gets
upon the posterior surface of the tibia, and
sends off, through the deficiency left between
the tibia and fibula at the superior part, a
branch which is distributed to all the muscles
upon the fore part of the leg. The artery then
creeps along the back of the bones for some
way, and passing between them above, where
the fibula is anchylosed with the tibia, it re-
appears on the anterior part of the leg in the
situation of the anterior tibial artery; at this
place it detaches some very small branches,
which frequently divide and unite again, to
produce a most singular reticulation or plexus
of vessels, which closely adheres to the trunk
of the artery, and is continued with it as far as
the articulation of the tibia with the metatarsal
bone, where it disappears without seeming to
answer any useful design. This plexus resem-
bles in appearance exactly the division of the
arteries of the extremities, which has been
described by Mr. Carlisle in the tardigrade
quadrupeds, but differs from it in this cir-
cumstance, that the trunk of the artery is pre-
served behind it, without suffering any material
diminution of its size.

“ The anterior tibial artery furnishes no
branch of any importance during the time it is
proceeding along the fore part of the leg. It
passes under the strong ligament which binds
down the tendons of the anterior muscles of
the leg, and over the fore part of the joint on
the inside of the tendon of the tibialis anticus,
at which places it distributes some branches
which inosculate with the other arteries round
the joint; it then pursues its course in the
groove along the anterior surface of the meta-
tarsal bone, and covered by the tendon of the
flexor digitorum. On coming near the foot it
sends off an artery, which divides, behind the
joint of the internal toe, into two branches ;

Z

338

one goes between the internal and middle toes,
ramifies upon both their joints, and unites with
the artery in the sole of the foot; the other is
distributed between the internal toe, and the
pollex or toe which occupies the place of the
great toe; the main artery now passes to the
sole of the foot through a hole in the meta-
tarsal bone, left for the purpose, when the
original parts of this bone were united by ossi-
fication. In this situation the artery might
receive the name of the plantar. It has
scarcely passed through the bone, when it di-
vides into six branches; three of these are
distributed to the tendons and ligaments, &c.
on the outside of the foot and the back of the
metatarsus, anastomosing with the descending
branches of the peroneal artery; the fourth
branch supplies the pollex, and also sends a
branch from the metatarsus. The remaining
branches are designed for the three principal
toes; one dips in between the internal and
middle toe, unites with the anterior branch of
the metatarsal artery, and is distributed to the
sides of these toes as far as their extremity.
The other divides, between the external and
middle toe, into two branches, which run upon
the opposite side of each of these toes to the
end.

“ When the feet are webbed, the digital ar-
teries send off numerous branches, which, ra-
mifying in the membrane between the toes,
establish a communication with each other.
The present description has been taken from
birds which possess three principal toes, and
the back toe or pollex; but no material diffe-
rence can be expected in those with a greater
number of toes.

“* After the trunk of the aorta has detached
the ischiadic arteries, it is continued along the
spine as the arteria sacra media (29, fig. 170),
sending off small branches analogous to the
lumbar arteries, one of which ascends upon
the rectum, supplies the place of the inferior
mesenteric (30, fig. 170), and unites with the
superior mesenteric as already mentioned. The
aorta separates above the coccygeal vertebra
into three branches; two of these, (the hypo-
gastric arteries, 31, fig. 170,) proceed laterally,
and are distributed to the neighbouring parts,
and to the kidneys and oviduct; the third
branch (the coccygeal artery, 32, fig. 170) de-
scends to the very point of the tail, upon the
muscles and quills of which its branches are
exhausted.

“ The arterial system of birds, besides the
distinguishing characters above-mentioned, dif-
fers from that of mammals chiefly in the fre-
quent anastomoses, which exist more especially
amongst the arteries of the head and the
viscera. Similar communications occur between
the veins, which are even in some instances
more singular and unaccountable, as will be
perceived by the following description, which
has been taken principally from the Goose,
Duck, and Common Fowl.”

Besides the remarkable arterial plexuses men-
tioned in the general description, as the orbital,
the temporal, the spermatic plexuses, &c., that
which Barkow has described under the name of

AVES.

the plexus of the organ. of incubation ( Brit-
organe) deservese special notice. It is repre-
sented at 17, 18, fig. 170, and is composed
of branches coming from the posterior thoracic,
abdominal, cutaneous, and ischiadic arteries,
which ramify beneath the integument of the
abdomen, and form, by their unions, a rich net-
work of vessels which becomes truly extraordi-
nary in the time of hatching. At this period
many birds pluck off the feathers from the seat
of incubation, probably thereto impelled by the
great degree of heat caused by the influx of
blood into the incubating plexus.

Fig. 171.

EU/ZN

a. wa

~ 7, ee -
OT $

fh

Veins of a Fowl.

““ Veins—The venous system returns the
blood to the heart by means of three trunks; two
of these, for the convenience of description, we
shall call the subclavian veins (a a, fig. 166),
although they do not correspond in every respect
with the veins of this name in mammalia; the
other trunk is analogous to the inferior vena cava.

“ The subclavian vein (a, fig. 171) is com-
posed of the jugular and vertebral, and the
veins which belong to the superior extremity or
wing.

“ The vertebral vein is lodged in the same
canal with the vertebral artery; it anastomoses
between the vertebre with the veins upon the

AVES.

sheath of the medulla spinalis, which are the
continuation of the sinuses of the brain; in
conjunction with these, therefore, the vertebral
vein may be considered as answering the pur-
pose of the internal jugular of mammalia. It
appears also to form at the basis of the cranium
a free communication with the jugular vein,
and to receive, by occasional branches, blood
from the muscles of the neck.

“ The jugular vein (b) is a single trunk in
birds, and does not admit of the distinction
into external and internal; it proceeds super-
ficially along the side of the neck in company
with the vagum nerve. The vein of the
right side exceeds the other in size; it is often
twice as large. The jugular vein receives several
lateral branches from the muscles and integu-
ments of the neck (d), the esophagus, &c. (the
veins from the crop joining the jugular are
shewn at c): one of these near the head is
much longer than the rest (e); it lies deep
amongst the muscles, and appears to com-
municate with the vertebral vein. There is a
branch of the jugular which goes to the supe-
rior larynx amongst the muscles of the tongue
and of the os hyoides, and another for the
muscles within the jaws and the integuments
in the back of the mouth; these might be
called the lingual, thyroid, and submazillary
veins (g h i).

“« The jugular veins form a most remarkable
communication with each other immediately
below the cranium, by means of a cross
branch, generally of an equal size with the
trunks themselves. From each side of the
arch thus formed there issues a large vessel,
which is made up of the veins of the external
| of the head; one of these passes round

e articular bone, and apparently penetrates
the joint of that bone with the lower jaw; it
appears in several branches upon the side of
the cheek, and spreading from the ear in the
manner of the portio dura nerve of the human
subject, and contributes to form a plexus of
veins below the posterior part of the orbit (A),
similar to the arterial plexus already described in
thatsituation. The principal branch of the veins of
the head passes obliquely round the interarticular
(or pterygoid) bone, and below the orbit divides
into several large vessels, one of which belongs
to the back part of the palate ; another ascends
on the orbit, and unites with the ophthalmic
vein ; and a third is distributed to the interior
of the organ of smell, the palate, and the
external parts of the upper and lower jaws.
These branches produce plexuses along the

base of the orbit and the external edge of the —

palate, which correspond to those of the arte-
ries before described. .

“ Tn all the subjects we dissected for the veins,
we failed to discover any direct communication
between the jugular vein and’ the sinuses of
the brain; and in every instance the external
veins of the head appeared to be sufficiently
large of themselves to produce the trunk of
the jugular. It may, therefore, be presumed
that if any branch analogous to the internal
jugular vein passes through the posterior fora-
men lacerum, it is very inconsiderable, and

339

incapable of transmitting the blood of the
brain.

“ The sinuses of the brain seem to discharge
their contents principally into some veins
which lie in the membrane forming the sheath
of the spinal canal, and these appear to dispose
of their blood gradually, as they descend in
the neck by means of lateral communication
with the vertebral veins. The sinuses, which
immediately open into the spinal veins, are
situated upon the back of the cerebellum, and
produce, by anastomoses with each other, with
the superior longitudinal sinus, and with others
along the side of the brain, an union of vessels
of a diamond shape.

“« The sinuses of the brain in birds generally
are irregular in their form, and consist of flat-
tened canals; and not only the sinuses on the
back of the cerebellum, but the spinal veins
appear so like extravasation, that accurate and
repeated observations are necessary to discover
them to be real vessels.

“ The principal sinuses, besides those upon
the cerebellum, are the superior longitudinal,
and one which runs along the lower edge of each
hemisphere of the cerebrum; there appears to
be also one upon the side of the cerebellum,
corresponding to the lateral sinus. All these
sinuses communicate with each other on the
back of the cerebellum as already mentioned.
The superior longitudinal sinus is continued at
its anterior part under the frontal and nasal
bones, and anastomoses with the ophthalmic
and nasal veins. There are other sinuses in
the several duplicatures of the dura mater,
which are too small to be easily traced or to
deserve much regard.

“The veins of the wings, or superior ex-
tremity, have a less curious distribution than
those of the head. The branches which are
derived from the parts within the chest, the
muscles about the scapula, and the pectoral
muscles, accompany the arteries of the same
parts so regularly that their course does not
require description.

“The axillary vein (1) lies considerably
lower in the axilla than the artery, but still
continues to receive corresponding branches;
(m indicates the great pectoral vein). The
trunk of the vein descends in the course of the
humeral artery, but more superficially ; in this
situation it may be called basilic, or more pro-
perly the humeral, vein (n). There is no vein
in birds which deserves the name of the ce-
phalic ; there are branches of the humeral vein,
accompanying the articular and profunda arte-
ries, and at the middle of the humerus a large
branch of the vein enters the bone; there are
also two very small branches which lie in close
contact with the humeral artery, which they
accompany nearly its whole length.

“ The principal vein of the wing divides into
two, opposite to the joint of the humerus with
the fore-arm. One of these branches (0) belongs
to the sides of the radius; it receives blood
from the muscles and skin on the upper part
of the fore-arm, but its chief vessels lie be-
tween the integuments of the fold of the wing.
The other branch of the humeral vein (p) crosses

Z2

340

the fore-arm, just below the articulation in
company with the nerve, and running along
the inferior edge of the ulna, receives a branch
from between the basis of each quill, is con-
tinued along the ligament which sustains the
rest of the quills to the extremity of the wing,
receiving many veins of the joints from the
Opposite side of the fingers. Besides these
large superficial veins of the fore-arm, there
appears to be one, and sometimes two, small
accompanying veins to the ulnar and interos-
seous arteries (¢).

“ The inferior vena cava (k), before it enters
the auricle (a), receives as usual the hepatic
veins (s); these are numerous, and open into
the cava as it passes behind the liver, or more
frequently within the substance of that viscus
in the back part. We have reckoned in the
Cock two large and two small hepatic veins
from the right lobe, and one large branch from
the left lobe, besides six minute veins, which
came indifferently from both lobes.

“ The trunk of the vena cava is very short
in the abdomen; it separates into two great
branches analogous to the primary éliac veins (t),
opposite to the renal capsules; these turn to
each side, and experience a very singular dis-
tribution. On coming near the edge of the
pelvis. each of these two veins forms two
branches; one of which collects the blood of
the lower extremity, as hereafter described ; the
other passes. straight downwards imbedded in
the substance of the kidney, and admits the
several emulgent. veins, which are very large,
and are seen to pass. for some way obliquely
in the kidney before their termination. Some-
times the emulgent veins are double, as in the
figure, (w). The descending branch of the iliac
also receives the ovarian veins, and when arrived
at the lower end of the kidney, divides into three
branches; one transmits the blood of the muscles
of the tail and parts adjacent; another accom-
panies the ureter to the side of the rectum, and
is distributed about the anus and parts of gene-
ration, answering to the hemorrhoidal veins;
the third (v, v) passes inwards to the middle line
between the kidneys, and there unites with the
corresponding branch of the opposite side.*
The vessel which is in this manner produced
(2) receives all the blood of the rectum from the
anus to the origin of the ceca, anastomosing
below with the branches of the hemorrhoidal
veins ; and at the upper part of the rectum,
it becomes continuous with the trunk of the
veins of the small intestines (x), forming the most
remarkable anastomosis in the body, both on
account of its consequences and the size of the
vessels by which it is effected. By means of
this communication, the blood of the viscera
and the external parts of the body flows al-
most indifferently into the vena cava and vena
porte (w); for the anastomosing vessels are suf-
ficiently large to admit the ready passage of a
considerable column of blood in proportion to
the whole mass which circulates in the body

* It is these branches which Professor Jacobson
supposes to carry venous blood into the kidneys,
for the purpose of supplying material for the uri-
nary secretion.

AVES.

of the bird; for instance, in the Goose the com-
municating veins of the pelvis are equal in
size to a goose-quill, and in the Ostrich and
Cassowary they are as thick as a finger. The
advantage which appears to result from this
remarkable union of vessels, is the prevention
of congestion, or the overloading either the
heart or liver with blood, as the one organ has
the power of relieving the other. It would
seem from this, as well as several other pro-
visions of the same kind, that the circulation
would be more liable to obstruction in birds
than other animals.* It is difficult to say, how-
ever, to what cause such an effect ought to be
ascribed. Is it from the compression sus-
tained by the heart and other viscera, by
means of the air-cells during respiration? or,
is the mode of progression by flight capable of
impeding the motion of the blood ?

“ The anastomosis of the pelvic veins, in
being the means of conveying common venous
blood into the liver, goes to prove that the
blood of the vena porte does not require any
peculiar preparation by circulation in the spleen
or other viscera, which has been conceived as
necessary by some physiologists to fit it for the
secretion of bile.

“‘ The vena porte (w) belongs almost exclu-
sively to the right or principal lobe of the liver.
It is formed by three branches. The splenic vein
is the smallest, and is added to the vena porte,
just as it penetrates the liver on the side of the
hepatic duct. The next is made of two
branches; of which one returns the blood of
the posterior gastric. artery, and therefore may
be called the posterior gastric vein ; and the
other is furnished by the pancreas and duode-
num, and therefore is the pancreatic vein.

The third and largest branch of the vena

porte is the mesenteric vein (a), which not only
collects the blood from all the small intestines,
but likewise receives the inferior mesenteric (z),
or vein of the rectum, which forms the com-
munication that has been described with the
pelvic veins.

“‘ The veins of the left lobe of the liver are
furnished in the goose by those which accom-
pany the anterior gastric artery, and some

ranches from the head of the duodenum.

“« The anterior gastric veins produce two small
trunks, which enter at the two extremities of
the fissure, in the concave surface of the left
lobe of the liver, as it lies upon the edge of
the gizzard; the veins from the head of the
duodenum furnish a small vessel which passes
backwards to penetrate the posterior part of
the fissure in the left lobe.

“ In the cock the veins that the left lobe of the
liver derives from the anterior gastric, are more
numerous than in the goose. |

“‘ The veins of the zone of gastric glands, and
of the lower portion of the esophagus, do not

* Besides their anastomoses the principal vis-
ceral veins are remarkable for their large size in
the Diving Birds. Cuvier (Legons d’ Anat. Comp.
iv. p- 274) has especially noticed the dilatation of
the inferior cava of the Grebes ( Colymbus ), which
reservoir he compares with that formed by the
hepatic veins in the Seal.

» SO

AVES. 341

contribute to the secretory vessels of the liver,
but proceed to the superior part of that viscus,
to terminate in the vena cava, as does also the
umbilical vein.

“The vein which returns the blood of the
inferior extremities is divided in the pelvis
into two branches, which correspond with the
femoral and ischiadic arteries; the one passes
through the ischiadie foramen, and the other
through the hole upon the anterior margin of
the pelvis; but the proportion they bear to
each other in magnitude is the very reverse of
what occurs in the arteries; for the anterior
vein is the principal one, whilst the other is
not a very considerable vessel, and receives its
supply of blood from the muscles at the pos-
spre ae of the joint.

“ The femoral vein (a a), immediately without
the pelvis, gives branches on both sides, which
receive the blood of the extensor and adductor
muscles at their superior part: the trunk passes
obliquely under the accessory muscle of the
flexor digitorum, and over the os femoris,
where it liessuperficially ; itthen winds under the
adductor muscles, and gets into the ham (b b),
where it receives many muscular branches,
and comes into company with the artery and
nerve. It here divides into the tibial (c c) and
peroneal veins. The first is joined by some
branches from the surface of the joint answer-
ing to the articular arteries; it also receives the
anterior tibial vein which accompanies the
artery of the same name. The tibial vein pro-
ceeds down the leg along with the artery on
the inside of the deep-seated flexors of the
heel: it turns over the fore part of the articu-
lation of the tibia with the metatarsal bone,
in order to get upon the inner side of the me-
tatarsus; above the origin of the pollex, it
receives a communicating branch from the

roneal vein, and immediately after two
branches from the toes: one of them comes
from the inside of the internal toe; the other
arises from the inside of the external and mid-
dle toes, unites at the root of the toes in the
sole of the foot, and is joined by a branch from
the pollex, before its termination in the internal
vein of the metatarsus.

“The peroneal vein derives its principal
branches along with those of the peroneal
artery, from the muscles on the outside of the
leg. The trunk of the vein comes out from
the peroneal muscles, and passes superficially
over the joint at the heel, and along the outside
of the metatarsus; near the pollex, or great toe,
it sends a branch round the back of the leg,
to communicate with the tibial vein; after
which it is continued upon the outside of the
external toe to the extremity, receiving anas-
tomosing branches from the tibial vein.

“ Where the veins run superficially upon the
upper and lower extremities, they seem to
supply the place of the branches of the cepha-
lic, basilic, and the two saphene; but the
analogy is lost upon the upper arm and thigh,
these branches forming deep-seated trunks ;
this constitutes the greatest peculiarity in the
distribution of the veins in the extremities of
birds.”

Respiratory organs.—In the course of this

article we have frequently had occasion to allude
to the extent and activity of the respiratory func-
tion in the Class of Birds ;* nevertheless the
organs subservient to this function manifest
more of the peculiarities of the Reptilian than
of the Mammalian type of formation.

The lungs are confined, as in the Tortoise,
to the back part of the thoracic-abdominal
cavity, being firmly attached to the ribs and
their interspaces; and, as in the Serpent, they
communicate with large membranous cells
which extend into the abdomen and serve as
reservoirs of air. ;

In those aquatic Birds, which are deprived
of the power of flight, as the Penguins, the air
receptacles are confined to the abdomen; but
in the rest of the class they extend along the
sides of the neck, and, escaping at the chest and
pelvis, accompany the muscles of the extre-
mities. They also penetrate the medullary
cavities and diploé of the bones, extending in
different species through different proportions of
the osseous system, until in some birds, as
the Horn-bill, every bone of the skeleton is
permeated by air. ' ;

There is, indeed, no class of Animals which
are so thoroughly penetrated by the me-
dium in which they live and move as that of
Birds. Fig. 172.

The lungs (w, fig.172)
are two in number, of a
lengthened, flattened,oval
shape, extending along
each side of the spine
from the second dorsal
vertebra to the kidneys,
and laterally to the junc-
tion of the vertebral with
the sternal ribs. They f
are not suspended freely }
as in Mammalia, but are {
confined to the back part!
of the chest by cellular}
membrane, and the pleura Wi
is reflected over thesternal {\\\ J
surface only, to which the
strong aponeurosis of the 6“
diaphragmatic muscles is
attached. They are con-
sequently smooth and al
even on the anterior ight lung of a Goose.
surface, but posteriorly are accurately moulded to
the inequalities of the ribs and intercostal spaces.

The lungs in general are of a bright red
colour, and of a loose spongy texture. The
bronchi (u, fig. 163; a, fig. 172) penetrate their
mesial and anterior surfaces about one-third
from the upper extremities; they divide into
four, five, or six branches, which diverge as
they run along the anterior surface ; some in-
complete cartilaginous rings are found through
their entire extent.

The orifices of the air-cells of the lungs (cc,
Jig. 172) open upon the posterior parietes of
the bronchial tubes, while the extremities of
these tubes terminate by wide openings (0 6,
Jig. 172) in the thoracic and abdominal air-
receptacles. These orifices are oblique, and

* According to Lavoisier, two Sparrows consume
as much oxygen in a given time as one Guinea-pig,

342

are partially covered by a slight projection of
membrane. :

The pulmonary artery divides, almost im-
mediately after its origin, into two branches,
one to each lung; the ramifications of each
artery form plexuses upon the air-cells, and
freely anastomose with the pulmonary veins;
these leave the lung by a single trunk, and
the two pulmonary veins unite into one before
terminating in the left auricle.

The thoracic-abdominal cavity is subdivided
and intersected by a number of membranes ;
the greater part of the cells thus formed are
filled with air. The texture of their parietes
possesses considerable firmness in the larger
birds, as the Ostrich and Cassowary, in which
they were described by the French Academi-
cians as so many distinct bags.

The innermost layer of the air-receptacles
can be separated from the outer layer, and is a
continuation of the lining membrane of the
bronchial tube; the outer layer is a serous
membrane, and appears to form the cells by a
series of reflections of what may be regarded
as the pleura or peritoneum.

These large membranous receptacles into
which the extremities of the bronchial tubes
open are disposed with sufficient general regu-
larity to admit of a definite description and
nomenclature.

Fig. 173.

7
By,
CZ

Ait-receptacles of a Swan.

AVES.

The first or inter-clavicular air-cell (a, fig.
173) extends from the anterior part of each
lung, forwards to the i of the fur-—
culum, anterior to which it dilates in the
Gannet and many other birds into a large
globular receptacle. In the Vultures it is di-
vided into two lateral receptacles, between
which the large crop is situated. A thin fan-
shaped muscle is extended from the anterior
edge of the furculum, over the interclavicular
air-cell in these and some other birds.

The anterior thoracic cell (b) contains the
lower larynx and bronchi, and the great vessels
with their primary branches to the head and
wings. It is traversed by numerous mem-
branous septa, which connect the different
vessels together, and maintain them in their
situations. The air passes into the posterior
part of this receptacle by two openings at the
anterior part of the lungs. The deep-seated
air-cells of the neck are continued from it
anteriorly.

The lateral thoracic cells(d) are continued on
each side from a foramen on the inner edge of
the lung, situated just opposite the base of the
heart; they are covered by the anterior tho-
racic air-cell, and from them the air passes
into the avillary and subscapular cells, into
those of the wing, and into the humerus (e).
They also communicate with the cellula cordis
posterior (c), behind the heart and bronchi,
which cell is often subdivided into several
small ones.

The cellule hepatice are of much larger
size; they are two in number, of a pyramidal
figure, with their bases applied to the lateral
thoracic cells, and their apices reaching to the
pelvis: they cover the lower portions of the
lungs and the lobes of the liver; they receive
air from several foramina situated near and at
the external edge of the lungs. ?

The cellule abdominales commence be-
neath the cellule hepatice at the inferior ex-
tremity of the lungs, where the longest branches
of the bronchize open freely into them. (A
bristle is passed through one of these openings
in the figure.) They are distinguished into
right (f.) and left (h); the former is gene-
rally the largest receptacle in the body; it ex-
tends from the last ribs to the anus, and covers
the greater part of the small intestines, the
supra-renal gland, and kidney of the same
side. The left abdominal cell (A) contains the
intestines of its own side, and is attached to
the gizzard. In some large Birds, as the
Gannet, it is separated from the right recep-
tacle by a mediastinal membrane (g) which is
continued from the gizzard to the anus.

Both the abdominal receptacles transmit
air to the pelvic cells (i, kK) of their res
tive sides, and to several small and extremely’
delicate cells between and behind the coils of
intestine. One of these is continued round the
fold of the duodenum and pancreas to the
—_ and has been termed the duodenal
cell.

From the inguinal cell are continued the in- —
termuscular gluteal and femoral cells, which
surround the head of the femur, and commu-
cate with that bone by an aperture (/) situated

AVES.

immediately anterior to the great trochanter,
except in those Birds in which the femur
retains its medulla.

The cervical air-cells are continued from the
large clavicular cell, and form in the Argala a
singular appendage or pouch, contained in a
loose fold of integument, which the bird can
inflate at pleasure. °

In the Pelecan and Gannet extensive air-
cells are situated beneath almost the whole of
the integument of the body, which is united to
the subjacent muscles only here and there by
the septa of the cells and the vessels and nerves
which are supported by the septa in their pas-
sage to the skin. The large pectoral muscles
and those of the thigh present a singular ap-
pearance, being, as it were, cleanly dissected
on every side, having the air-cavities above and
beneath them. The axillary vessels and nerves
are also seen passing bare and unsupported by
any surrounding substance through these cavi-
ties. Numerous strips of panniculus carnosus
pass from various parts of the surface of the
muscles to be firmly attached to the skin; a
beautiful fan-shaped muscle is spread over the
inter-clavicular or furcular air-cell. The use
of these muscles appears to be to produce a
rapid collapse of the superficial air-cells, and
an expulsion of the air, when the bird is about
to descend, in order to increase its specific
gravity, and enable it to dart with rapidity upon
a living prey.

The air-receptacles of the thoracic-abdominal
cavity present varieties in their relative sizes
and modes of attachment in different birds. In
the Raptores they are principally attached pos-
teriorly to the ribs, the diaphragmatic aponeu-
rosis covering the lungs, and to the kidneys;
while in the Grallatores they have anterior
attachments to the intestines in many places.

The singular extension of the respiratory
into the osseous system was discovered almost
simultaneously by Hunter and Camper, and
ably investigated by them through the whole
class of Birds. The air-cells and lungs can
be inflated from the bones, and Mr. Hunter
injected the medullary cavities of the bones
from the trachea. It is stated that if the femur
into which the air is admitted be broken, the
bird shall not be able to raise itself in flight.
It is certain that if the trachea be tied, and an
opening be made into the humerus, the bird
will respire by that opening for a short period,
and may be killed by inhaling noxious gases
through it.* If an air-bone of a living bird,
similarly A emma be held in water, bubbles
will rise from it, and a motion of the contained

™ «T cut the wing through the os humeri in a
Fowl, and tying up the trachea found that the air
agg to and from the lungs by the canal in this

ne. The same experiment was made with the
os femoris of a young Hawk, and was attended with
a similar result. But the passage of air through
the divided parts, in both these experiments, espe-
cially in the last, was attended with more difficulty
than in the former one; it was indeed so great, as
to render it impossible for the animal to live longer
than evidently to prove that it breathed through
the cut bone.” — Hunter’s Animal (Economy, p. 94.

343

air will be exhibited, synchronous with the
motions of inspiration and expiration.

The proportion in which the skeleton is.
permeated by air varies in different Birds. In
the Penguin ( Aptenodytes), which we have
examined for this purpose, air is not admitted
into any of thebones. Its chief progression being
in water, the specific levity of the body gained
by the substitution of air for marrow would be
rather a detriment than an advantage. The
condition of the osseous system, therefore, which
all birds present at the early periods of exist-
ence, is here retained through life.

In the large Struthious Birds, which are re-
markable forthe rapidity of their course, the
thigh-bones and bones of the pelvis, the ver-
tebral column, ribs, sternum and scapular
arch, the cranium and lower jaw, have all air
admitted into their cavities or cancellous struc-
ture. The humeri and other bones of the
wings, the tibie and distal bones of the legs,
retain their marrow.

With the exception of the Woodcock, all
Birds of Flight have air admitted to the
humerus.

The Pigeon tribe, with the exception of the
Crown Pigeon, have no air in the femur, which
retains its marrow. In the Owls also the femur
is filled with marrow; but in the Diurnal Birds
of Prey, as in almost all other Birds of Flight,
the femur is filled with air.

In the Pelecan and Gannet the air enters all
the bones with the exception of the phalanges
of the toes. In the Hornbill even these are
permeated by air.

Mr. Hunter* has given the following cha-
racters as distinguishing the hones which receive
air. They may be known—“ first, by their
less specific gravity; secondly, by their retain-
ing little or no oil, and, consequently, being
more easily cleaned, and when cleaned, ap-
pearing much whiter than common bones:
thirdly, by having no marrow, or even any
bloody pulpy substance in their cells ; fourthly,
by not being in general so hard and firm as
other bones; and, fifthly, by the passage that
allows the air to enter the bones, which can
easily be perceived.”

We have reserved for this section the de-
scription of the foramina by which the air
penetrates the different bones. ‘These openings
may be readily distinguished in the recent
bone, since they are not filled up by blood-
vessels or nerves, but have their external edges
rounded off.

In the dorsal vertebre the air-orifices are
small, numerous, and irregular ; situated along
the sides of the bodies, and the roots of the
spinous processes, the air passes into them
directly from the lungs. In the two or three
lower cervical vertebre the air-holes are in the
same situation, but receive the air from the
lower cervical or clavicular air-cells: in the
remainder of these vertebre the air-holes are
situated within the canal lodging the vertebral
artery, and communicate with the lateral air-
cells of the neck.

* Animal Gconomy, p. 91.

344 AVES.

The air-holes of the vertebral ribs.are situated
at the internal surface of their vertebral extre-
mities, and appear like tnose of the contiguous
vertebre to have an immediate communication
with the lungs. The sternal ribs, or ossified costal
cartilages, have also internal cavities which
receive air from the lateral thoracic cells by
_ means of orifices placed at their sternal ex-
tremities.

The orifices by which air is admitted to the
sternum are exceedingly numerous, but are
principally situated along the mesial line of the
internal surface, opposite the origin of the
keel, forming a reticulation at that part; the
largest foramen is near the anterior part of
the bone; some smaller ones occur at the
costal margins. All these orifices commu-
nicate with the thoracic air-receptacles.

The scapula is perforated by several holes
at the articular extremity, which admit air
into its cancellous structure from the axillary
cell.

The coracoid has small air-holes at both ex-
tremities ; the largest is situated on its inner
surface, where it is connected with the clavicle
or furculum.

The furculum receives air principally by a
small hole in the inner side of each of its
scapular extremities, which communicates with
the clavicular air-cell-

The air-hole of the humerus is of large size,
and situated at the back part of the head of
the bone, below the curved inferior process.
It communicates with the axillary air-cell, and
transmits the air to the cavity of the bone by
several cribriform foramina.

The air-holes of the pelvic bones are situated
irregularly on the inner surface upon which the
kidneys rest, and must therefore receive air
from continuations of the abdominal receptacles
around the kidneys.

The air-hole, or rather air-depression of the
femur, is situated at the anterior part of the
base of the trochanter; it receives air from the
gluteal cell, and transmits it by several small
foramina into the interior of the bone. In
the Ostrich, the air-holes are situated at the
posterior part of the bone at both of its extre.
muties.

The cavities of the long bones into which
air is thus admitted are proportionally larger
than in the corresponding bones of Mammalia,
and are characterized by small transverse
osseous columns which cross in different di-
rections from side to side, and are more nu-
merous near the extremities of the bone; they
abut against and strengthen, like cross-beams,
the parietes of the bone. .

We have sometimes succeeded in filling with
fine size-injection the minute arteries which
ramify on the membrane lining these cavities,
but the vascularity of this membrane is by no
means very remarkable.

The lower jaw receives its air by means of
an orifice situated upon each ramus behind the
tympano-maxillary articulation. Mr. Hunter
was in doubt as to whether the lower jaw
derived its supply of air from the Eustachian
tube or the trachea where it passes along the

neck.* In a Pelecan which we dissected for
the purpose we found it to be supplied by an
air-cell which surrounded the joint, and was con-
tinuous with the upper cervical air-cells. The

bones of the cranium and upper jaw have com-
munications with the Eustachian tube, but not

with the nasal passages, which are every where
lined with an impervious pituitary membrane.

Various explanations have been given of the
final intention of the condition of the respiratory
system above described.

The extension of this system by means o
continuous air-receptacles throughout the body
is subservient to the function of respiration,
not only by a change in the blood of the
pulmonary circulation effected by the air of the
cells on its re-passage through the bronchial
tubes, but also, and more especially, by the
change which the blood undergoes in the ca-
pillaries of the systemic circulation, which are
in contact with the air-receptacles. The free
outlet to the air by the bronchial tubes does
not, therefore, afford an argument against the
use of the air-cells as subsidiary respiratory
organs, but rather supports that opinion, since
the inlet of atmospheric oxygenated air to be
diffused over the body must be equally free.

A second use may be ascribed to the air-
cells as aiding mechanically the actions of
respiration in Birds. During the act of inspi-
ration the sternum is depressed, the angle
between the vertebral and sternal ribs made
less acute, and the thoracic cavity proportion-
ally enlarged; the air then rushes into the
lungs and into the thoracic receptacles, while
those of the abdomen become flaccid: when
the sternum is raised or approximated towards
the spine, part of the air is expelled from the
lungs and thoracic cells by the trachea, and
part driven into the abdominal receptacles,
which are thus alternately enlarged and dimi-
nished with those of the thorax. Hence the
lungs, notwithstanding their fixed condition,
are subject to due compression through the
medium of the contiguous air-receptacles, and
are affected equally and regularly by every
motion of the sternum and ribs.

A third use, and perhaps the one which is
most closely related to the peculiar exigences
of the bird, is that of rendering the whole
body specifically lighter; this must necessarily
follow from the dessication of the marrow and
other fluids in those spaces which are occupied
by the air-cells, and by the rarefaction of the
contained air from the heat of the body.

Agreeably to this view of the function of the
air-cells, it is found that the quantity of air
admitted into the system is in proportion to the
rapidity and continuance of the bird’s motion;
and that the air is especially distributed to those
members whieh are most employed in loco-
motion; thus the air is admitted into the wing-
bones of the Owl, but not into the femur;
while in the Ostrich the air penetrates the
femur, but not the humerus or other bones of
the wing.

A fourth use of the air-receptacles, which
has not hitherto been saapenaete relates to the

* Loc. cit. p. 93,

phat De ee

ree =U

AVES.

mechanical assistance which they afford to the
muscles of the wings. This was first suggested
to us by observing that an inflation of the air-
cells in a Gigantic Crane ( Ciconia Argala )
was followed by an extension of the wings, as
the air found its way along the brachial and
anti-brachial cells.* In large birds, therefore,
which, like the Argala, hover with a sailing
motion for a long-continved period in the
» ase regions of the air, the muscular exertion
of keeping the wings outstretched will be les-
sened by the tendency of the distended air-cells
to maintain that condition. It is not meant to
advance this as any other than a secondary
and probably partial use of the air-cells. In
the same light may be regarded the use as-
signed to them by Hunter, of contributing to
sustain the song of Birds, and to impart to it
tone and strength. Itis no argument against this
function that the air-cells exist in birds which
are not provided with the mechanism necessary
to produce tuneful notes; since it was not pre-
tended by Hunter that this was the exclusive
and only office of the air-cells. The latest
writer on this subject has indeed proposed this
suggestion of Mr. Hunter as a novel idea.+

Air-passages.—The air-passages in birds
commence by a simple superior larynx, from
which a long trachea extends to the anterior
aperture of the thorax, where it divides into
the two bronchi, one to each lung. At the
place of its division there exists, in most birds,
a complicated mechanism of bones and carti-
lages moved by appropriate muscles, and
constituting the true organ of voice: this part
is termed the inferior larynz.

The tendency to ossification, which is ex-
emplified in the bony condition of the costal
cartilages and tendons of the muscles, is again
manifested in the framework of the larynx and
the rings of the trachea, which, instead of
being cartilaginous, as in Reptiles and Mam-
mals, are in most birds of a bony texture.

The superior larynx (fig. 151, 174, 175,)
is situated behind the root of the tongue, and
rests upon the uro-hyal element of the os hy-
oides, to which it is attached by dense cellular
texture.

It is composed of several bony and cartila-
ginous pieces, varying in number from four to
ten. The largest of these pieces constitutes
the anterior part of the larynx. It is of
an oval or triangular form, according as its
superior termination is more or less pointed :
it is regarded by Cuvier as analogous to
the anterior part of the cricoid cartilage,
(Lecons d’Anat. Comp. iv. p. 489,) but by
Carus it is considered as representing the
thyroid cartilage (f, fig. 151). The cricoid
cartilage in birds consists of the three osseous
pieces, which are situated at the posterior

* Onrelating this fact to Mr. Clift, he suggested
another use of the air-cells which is more generally
applicable, namely, that of assisting the actions of
the muscles by compressing and bracing them, ina
manner analogous to the action of the fasciz of the
extremities in Man.

t Jacquemin, Mémoire sur la pneumaticité des
oiseaux, 1835.

345

and inferior part of the upper larynx; the
middle one (g, fig. 151) is of an oblong form,
and varies in size, being larger than the lateral
ones in the Anatide, but smaller in the In-
sessores. The lateral pieces are connected at
one extremity with the thyroid piece, and at
the other to the middle oblong piece above
described, which completes the circle of the
laryngeal frame-work posteriorly. Carus re-
gards the first two incomplete tracheal rings
(gg) as the anterior part of the cricoid. The
arytenoid bones (/) rest upon the middle ob-
long portion of the ericoid, and extend for-
wards, being connected at their outer edge by
means of elastic cellular substance to the thy-
roid bone, and attached by their anterior ex-
tremities to the uro-hyal bone by means of
two small ligaments :* they form, by their inner
margins, the rima glottidis or laryngeal fissure.
This fissure (2, fig. 152) being thus bounded
by inflexible rigid substances is only susceptible
of having its lateral diameter varied according
to the degrees of separation or approximation to
which the arytenoid bones are subject. These
different states are produced by {appropriate
muscles, one pair of which may be regarded
as analogous to the T’hyreo-arytendidei, and the
other may be termed Constrictores glottidis.
The former of these muscles (k k, fig. 174,)
arise from the sides and posterior surface of
; the thyroid bone, and are

Fig. 174. inserted into the whole
length of the inner edge

of the arytenoid cartilages,
which they draw out-
wards, and consequently
open the laryngeal fissure.
The constrictores glottidis
in the Gigantic Crane arise
from the middle of the in-
ternal or posterior surface
of the thyroid bone, and are
inserted into the extremi-
ties of the arytenoid pieces.
According to Mr. Yarrell,
from whose Memoir the subjoined figures are
taken, the constrictors of the glottis (/, fig.175)
“ pass from the upper portion of the cricoid
(thyroid) cartilage along the crura of the ary-
tenoid cartilages, upon each outer edge of
which they are inserted.’’+
In either case these muscles
are enabled to close the la-
ryngeal opening with con-
siderable force, and with
such accuracy as to super-
sede the necessity of an
epiglottis. From the sim-
plicity of the structure just
described, from the situation
of the superior larynx with
relation to the rictus or gape
of the bill, and from the
absence of lips by which
this might be partially or

i,

| =\

a7

* Linn. Trans. vol. xvi. p. c06, pl. 17, figs.
3 and 4,

+ This description is taken from the Gigantic
Crane.—Ciconia Argala.

346 A AVES.

entirely closed, it is plain that it cannot be
considered as influencing the voice, otherwise
than by dividing or articulating the notes
after they are formed by the lower larynx.
The superior larynx presents, indeed, but few
varieties in the different species of Birds ; and
these relate chiefly to certain tubercles which
are observed in its anterior, but which vary in
number, and do not exist at all in some spe-
cies, as the singing birds; being chiefly pre-
sent in those birds which have a rough un-
musical voice. In the Pelecan, the Gigantic
Crane, and most of the Rasores, a process ex-
tends backwards into the cavity of the upper
larynx from the middle of the posterior surface
of the thyroid cartilage, and seems destined
to give additional protection to the air-passage.

The trachea CG, Jig. 170, 171) in Birds is
proportionally longer, in consequence of the
length of the neck, than in any other class of
animals, its length being further increased in
many species by convolutions varying in extent
and complexity. A species of Sloth ( Bradypus
tridactylus ) among Mammalia, and a species of
Crocodile ( Crocodilus acutus,) among Reptiles,
present an analogous folding of the trachea.

The trachea is composed in Birds of a
series of bony, and sometimes, as in the
Ostrich, of cartilaginous rings, included be-
tween two membranes. In those cases in
which they are of a bony structure, the ossi-
fication is observed to commence at the anterior
part of each ring, and gradually to extend on
both sides to the opposite part.

The tracheal rings, whether bony or cartila-
ginous, are, with the exception of the two
uppermost, always complete, and not, as in
most quadrupeds, where the windpipe bears a
different relation to the organ of voice, defi-
cient posteriorly. They differ in shape, being
sometimes more or less compressed. They
are generally of uniform breadth, but in some
species are alternately narrower at certain parts
of their circumference and broader at others,
and in these cases the rings are generally
closely approximated together, and, as it were,
locked into one ancther. This structure is
most common in the Grallatores, where the
rings are broadest alternately on the right and
left sides : the French Academicians have given
a good illustration of this structure from the
trachea of the Demoiselle Crane.

With respect to the diameter of the tracheal
rings, this may sometimes be pretty uniform
throughout, and the trachea will consequently
be cylindrical, asin the Insessores, the Gralla-
tores which have a shrill voice, the females of
the Natatores, and most Raptores and Ra-
sores: or the rings may gradually decrease in
diameter, forming a conical trachea, as in the
Turkey, the Heron, the Buzzard, the Eagle,
the Cormorant, and the Gannet; or they may
become wider by degrees to the middle of the
trachea, and afterwards contract again to the
inferior larynx; or, lastly, they may experience
sudden dilatations for a short extent of the
trachea ;—the Golden-eye (Anas clangula ), the
Velvet-duck (Anas fusca), and the Mergan-
ser ( Mergus serrator,), present a single en-

largement of this kind, in which the bony
rings are entire, and of the same texture as in
the rest of the tube. In the Golden-Eye the
trachea is four times larger at the dilatation
than at any other part. In the Goosander
( Mergus merganser_), the trachea presents two
sudden dilatations of a similar structure to that
above described. The trachea of the Emeu
(Dromaius ater) is also remarkable for a sud-
den dilatation, but in this instance the cartila-
ginous rings do not preserve their integrity at the
dilated part, but are wanting posteriorly, where
the tube is completed by the membranes only.

The bronchi (v, fig. 163) are straight, com-
pressed, delicate, and easily lacerable tubes ;
their rings, in most Birds,* form only a small
segment of a circle, and are situated at the
outer side of the tube, which is convex; the
inner side is completed by a membrane (mem-
brana tympaniformis) extended between the
extremities of the defective rings, and is flat.
The bronchial rings are weak and thin; in
Birds without true muscles of voice, they are
either of uniform thickness, or become gradually
thinner to their termination: in many Birds
which have the vocal muscles they grow sud-
denly thinner below the insertion of those
muscles: this is remarkable in Owls.

The muscles of the trachea are generally a
single pair, the sterno-tracheales, to which, in
some cases, a second pair is added, the cleido-
tracheales. The sterno-tracheales, which are
analogous to the sterno-thyroidei of mammalia,
arise from the costal processes of the sternum,
and ascend along the sides of the trachea, as
far in general as the superior larynx. The
cleido-tracheales (ypsilo-trachéens of Cuvier)
arise from the furculum or conjoined clavicles,
and pass along the sides of the trachea parallel
to the preceding.

Many birds possess only the tracheal and
superior laryngeal muscles, and have no proper
muscles of the inferior larynx. Cuviert divides
such birds into those which have the lower
larynx simple or without dilatations, as the
Rasores, and into those which have lateral
bony cavities at that part, as the males of the
Genus Anas, Cuy. and Mergus.

His next division in the order of complexity
of the vocal organs includes those birds which
have one pair of vocal or inferior laryngeal
muscles, the Broncho-tracheales ; these arise
from the sides of the lower part of the trachea,
and are inserted in one of the half-rings of the
bronchi at a less or greater distance from the
lower larynx in different birds; as, for exam
ple, in the first half-ring in the Genus Falco,
in most of the Grallatores, in the Genus
Larus (Gull), and Phalacrocorar (Cormo-
rant); in the third half-ring in the King-fisher
(Alcedo), and Goat-sucker ( Caprimulgus );
in the fifth half-ring in the Genus Ardea, Cuv.
in the Cuckoo and the Eagle-Owl ( Bubo
maximus); in the seventh half-ring in the

* In the Vultures, which have no true vocal
muscles, but only the sterno-tracheales, the first four
bronchial rings: are entire.

+ Anat. Comparée, tom. iv. p. 400.

a

AVES.

Barn-Owl (Strix flammea) and Horn-Owl
( Otus aurita ). The influence of these muscles
upon the voice must obviously be in proportion
as they shorten the bronchi and depress the
lower larynx, according to the different inser-
tions above mentioned.

A further degree of complexity in the organ
of voice is presented by the Psittacide or Par-
rot-tribe, which, according to Cuvier, have three
pairs of inferior laryngeal muscles.

-The Insessores, lastly, present five pairs of
muscles appertaining to the lower larynx, and the
organ of voice consequently attains its greatest
perfection in this order.

The peculiar structure of the lower larynx,
and the modifications of the trachea in relation
to its functions, will be treated of under the
article Organs of Voice.

Urinary Organs.—These consist in birds of
the kidneys, ureters, and a urinary receptacle,
which is more or less developed in all birds.

The kidney of the oviparous vertebrate ani-
mal is distinguished from that of the mammi-
ferous by the homogeneity of its substance,
which is not divided into a cortical and medul-
lary part, and by the tubuli uriniferi extending
to the surface of the gland there to form by
reiterated unions the ureter, and not terminating
in a cavity or pelvis in the interior of the kidney,
from which the ureter commences.

The kidneys (x x, fig. 182) of birds manifest
all the essential characters of the oviparous type
of structure. They are two in number, of an elon-
gated form, commencing immediately below the
lungs, and extending along the sides of the spine
as far as the termination of the rectum ; in which
course they are impacted in, and as it were
moulded to the cavities and depressions of the
pelvis. From this fixed condition it results that
they are generally symmetrical in position, not
placed one higher than the other, as in the mam-
malia. The posterior surface of the kidney pre-
sents inequalities corresponding to the risings
and depressions of the pelvis; the anterior sur-
face is smoothly convex or flattened ; but rising
into a series of prominences which correspond,
not to the eminences, but to the cavities of the
bones on which they rest : their inner or mesial
side is generally pretty regular and straight, but
the external edge is more or less notched.

From the nature of the integuments about to
be described, and the small amount of cutane-
ous transpiration in birds, the office of removing
from the system the superfluous watery part of
the circulating fluids devolves almost exclu-
sively upon the kidneys, and they are conse-
quently relatively larger than in the terrestrial
mammalia.

The kidneys vary in size in different birds,
being for example smaller in most of the
Grallatores, as the Bustard and Heron, where
the pelvis is short, than in the Rasorial
Order, in which it is of great extent. Where
they are short they are in general more promi-
nent, and this is so remarkable in some birds,
as the Owls, that in them they resemble some-
what in their superficial position the kidneys of
mammalia.

347

As might be expected from their relations
to the pelvis, the kidneys in birds present as
many varieties of outward configuration as
there are differences in the part of the skeleton
to which they are moulded. In some aquatic
birds, as the Grebe ( Podiceps and the Coot
(Fulica), the kidneys are more or less
blended together at their lower extremities, as
in most fishes. In the rest of the class they are
distinct from one another. ‘

In the Tern they are each divided by fissures
into seven or eight square-shaped lobes. In
the Eagle they each present four divisions; but
in these cases there are not distinct ureters to
each lobe as in the subdivided kidneys of mam-
malia.

The principal lobes are in general three in
number, the anterior or highest one being, in
some cases, the largest; while in others, as
the Pelecan, the contrary obtains, the lowest
division being most developed in this bird.

In the Emeu ( Dromaius ater) the kidney
presents only two lobes; the superior or anterior
one is the broadest and most prominent, being
of a rounded figure, and constituting one-third
of the whole ; the lower division is flattened,
and gradually tapers to a point. In the speci-
men we dissected we found the left kidney half
an inch longer than the right.

Each kidney is invested by its proper capsule,
a thin membrane, which also extends into the
substance of the gland, between its divisions: a
delicate layer of peritoneum is reflected over
their anterior surfaces.

The texture of the kidneys is much more frail
than in mammalia, readily yielding under the
pressure of the finger, to which they give a granu-
lar sensation as their substance is torn asunder,

In colour they resemble the human spleen.
Besides being divided into lobes, the surface of
the kidneys may be observed to be composed of
innumerable small lobules, separated by conti-
nuous gyrations like the convolutions of the
cerebral substance. The ultimate divisions of
the lobules and their intimate structure can
only be distinguished by observations on the
embryo, unless when the component follicles
are filled, as they occasionally are seen to be
after death, with the white salts of the urinary
secretion. The tubuli uriniferi, as Miiller ob-
serves,” may then be seen under the microscope
originating from every part of the internal sub-
stance of the lobules, extending to the gyrations,
uniting in the pinnatifid form, and coursing to
the margins of the lobules, all the inflexions of
which they follow. The pinnatifid ramification
of the uriniferous tubules 1s sometimes opposite,
sometimes alternate. Sometimes the branches
are simple, sometimes dichotomously divided :
but these ramuli appear scarcely smaller than
the branches from which they spring, and never
intercommunicate. They have been successfully
injected with size and vermilion, without any
of this material escaping into the secerning
vessels, which are much more minute. The
uriniferous ducts, when thus traced from the

* De Glandularum Structura, p. 92.

348
trunks to the branches, are seen to become con-
joined in pyramids, which adhere to the
branches of the ureter, are sent out in the gyri
_ of the lobules, and are outspread in a pinnatifid
figure on the surface, one next another, and
ultimately terminate in blind, rounded, but not
dilated extremities. The branches from the
convoluted lobules unite dichotomously, and
ultimately escape by a single duct—the ureter.

The arteries and veins of the kidneys have
already been described ; a difference of opinion,
however, prevails as to the course of the blood
in the veins which pass from the lower end of the
kidneys (at v, fig. 171) to the hypogastric vein
(z). Jacobson considers that the venous blood
is carried into the kidney by these veins, for the
purpose of affording the material for the urinary
secretion, analogous to the portal vein in the
liver; but Cuvier regards these veins as having
the same function as those which come from
the upper ends of the kidneys, and that they
return the blood from the lower ends of the
kidneys to aid in the formation of the portal
vein. Nicolai* also opposes the doctrine of a
venous circulation in the kidneys of Birds.
In favour of Jacobson’s theory is the small
size of the renal arteries, in consequence of
which the kidneys are not more coloured
than the liver, when the arterial system is in-
jected from the aorta, and the disproportionate
size of the veins, together with the analogy of
the cold-blooded ovipara, in which the exist-
ence of a secreting system of veins in the kid-
heys is now generally admitted.

The ureter (y, fig. 163, 182; h, h, fig. 176)
has the same structure as in themammalia. It
is continued down along the anterior surface of
the kidney towards the mesial side; here and
there imbedded in its substance, forming a
series of dilatations corresponding to the prin-
cipal lobes or enlargements of the gland, and
receiving the branches of the tubuli uriniferi as
it passes along. But these slight reservoirs do
not present any parts corresponding to the
mammille and their infundibula of mam-
malia. Below the kidney the ureters pass be-
hind the rectum, becoming connected to, and
after a short distance involved in its coats;
they ultimately terminate upon valvular emi-
nences, in a depression at the lower part of the
urinary sac; the terminal papille of the ureters
are situated with the orifices of the genital
ducts, in the same segment of the cloaca,
which is therefore termed the urethro-sexual
cavity (e, fig. 176).

The space intervening between the urethro-
sexual cavity and the valvular termination of
the rectum (c, fig. 176) forms a cavity more or
less developed in different birds, but always
distinct in the smoothness of its lining mem-
brane from the rectum, which has a more vas-
cular and villous internal tunic. The birds in
which this rudimental urinary bladder presents
the largest capacity are the Owls, many of the
aquatic birds, as the Pelecan, Willock, Grebe,
Swan, &c.; some of the Wading Order, as the

* Oken’s Isis, 1826, p. 414.

AVES.

Bittern and Bustard, but more especially the
Ostrich, among the Cursores, in which the
urinary receptacle is represented as laid open

(d, fig. 176).

Cloaca of the Ostrich.*

The Supra-renal Glands, Renal capsules,
Glandule succenturiate (d, d, fig. 182) are
small bodies, usually of a bright yellow colour,
situated on the mesial or inner side of the su-
perior extremities of the kidneys; closely at-
tached to the coats of the contiguous large veins
and in contact with the testes in the male 3; and
the left one adhering to the ovary in the female.
They vary in shape, being sometimes of a
round, flattened, oval, or irregularly triangular
figure. They are proportionally smaller than
in mammalia, being in the Goose each about
the size of a pea. |

They present, like the kidneys, a homoge-
neous texture throughout, and do not exhibit
the alternate strata of different-coloured sub-
stances as in mammalia. In the Gigantic Crane
we found the texture of the supra-renal glands
to be coarsely fibrous; in the Hornbill they
were granular, similar to the kidney; in the
Pelecan they were of a granular but more
pulpy texture.

There is no cavity in the supra-renal glands.
The veins which return the blood from them
are of proportionally large size, as in all the

arenchymatous bodies without excretory ducts.

he supra-renal glands have been found to
present a slight enlargement corresponding with
the increased development of the sexual organs ;
and it has been conjectured that their function
is related to that of the generative system.

Thyroid Glands. In many birds, as the
Vultures, Falcons, Starling, Magpie, Heron,
Bustard, and in most Aquatic birds, two glands
are found, one on each side of the trachea, ver
near the lower larynx and frequently attached
to the jugular veins. They are regarded as the
analogues of the thyroid glands. In addition
to these there are two small glands, in the Gan-
net, attached to the upper part of the commence-
ment of each bronchus.

* From Memoires du Muséum, tom. xv. pl. 2, fig. 1.

AVES.

Peculiar Secretions.—The unctuous fluid
with which Birds lubricate their feathers is
secreted by a gland which is situated above the
coccyx or uropygium, This gland consists of
two lateral moieties conjoined. As might be
expected, it is largest in the birds which frequent
the water. In the Swan it is an inch and a
half in length, and has a central cavity, which
serves as a receptacle for the accumulated secre-
tion; but this cavity has not been observed in
other species. Each lateral portion is of a
pyriform shape, and they are conjoined at the
apices, which are directed backwards and are
perforated by numerous orifices. The longitu-
dinal central cavities also present internally nu-
merous angular openings, in which there are
still smaller orifices. The surrounding glandu-
lar substance consists of close-set almost paral-
lel straight tubules,and is not irregularly cellular.
The tubules extend to the superficies of the
gland, without ramifying or intercommunicating,
and preserve an equable diameter to their blind
extremities. The tubules are longest at the
thickest part of the gland, and become shorter
and shorter towards the apex.

Tegumentary system.—This is composed, as
in Mammalia and Reptilia, of the corium or
derm, epiderm, and its appendages, and an
intermediate layer of unhardened epiderm with
colouring matter, called rete mucosum.

The corium, or true skin, is very thin, as in
the cold-blooded Ovipara. It adheres to the
subcutaneous muscles by cellular tissue, which
is frequently the seat of accumulation of dense
yellow fat; and it is moved by muscles which
at the same time raise and ruffle the plumage
which it supports.

The rete mucosum rarely contains any co-
louring matter where the feathers grow; at
this part the skin is of a pale, greyish colour,
or pink, from the colour of the blood which
circulates in it. But in the naked parts of
the integument, as the cire, the lore, the
comb, the wattles, the naked parts of the head
and neck in some birds, and the tarsi and
toes, the rete mucosum frequently glows with
the richest crimson, orange, purple, green,
black, and a variety of other tints, of which
the planches coloriés and the different zoological
monographs of families of birds afford nu-
merous examples.

The epidermis is in some places continued
as a simple layer over the corium, following
its wrinkles and folds, as around the naked necks
of some Vultures. It is moulded upon the
bony mandibles to form the beak, and in some
birds adheres to osseous protuberances on the
cranium, where it forms a species of horn; and
it is remarkable that these instances occur chiefly
in those orders of birds, the Cursores and
Rasores, which are most analogous to the Ru-
minantia among quadrupeds: the Cassowary
and Helmeted Curassow are examples. The
cuticle is sometimes developed into spines or
spurs, as upon the wing of the Secretary-bird,

assowary, the Apteryx, and the Palamedea ;
and upon the tarsi of the Gallinaceous Birds.
The claws which sheath the ungueal phalanges
of the feet assume various forms adapted to

849

the habits and manner of life of the different
orders. A remarkable artificial ‘form is given
to the claw of the middle toe in certain birds ;
the inner edge being produced and divided
into small parallel processes like the close-set
teeth of a comb (fig. 132.) These teeth are not
reflected or recurved, as they might be expected
to be, if they had been intended to serve as
holders ofa slippery prey, but are either placed
at right angles to the claw or are inclined to-
wards its point. The Common Barn-Owl ( Strix
Jlammea ), the Goat-sucker genus ( Caprimul-
gus), the Heron and Bittern kind ( Ardeide,
Vig.), afford examples of this structure; and
as each species of bird appears to be infested
by its peculiar louse (Nzrmus ), the solution
of the final intention of so singular a con-
trivance, which is limited to so few species,
and these of such different habits, may yet
be afforded by the entomologist. At least
it would be worth while to examine the pa-
rasitic animals of the species so provided, with
the view of determining whether they pos-
sessed superior powers of adhesion which
might require the application of a comb in the
birds infested by them.*

With respect to the scales which defend
the naked parts of the legs of birds, they do
not differ from those of Reptiles. Their form
and disposition, as has been already observed,
have afforded distinctive characters to the zoo-
logist. In most of the Raptores, the Psitta-
cide, the Rasores, the Grallatores, and the
Natatores, the scales are polygonal, small,
and disposed in a reticulate form ; the birds
so characterized formed the Retipedes of Sco-
poli. In the rest of the class the tarsi are
covered anteriorly with unequal semi-annular
scales, ending on each side in a longitudinal
furrow, and these birds were termed the ‘ Scw-.
tipedes.’+

The four classes of vertebrate animals have
each their characteristic external covering: the
cold-blooded Ovipara are naked, or their ex-
ternal surface is defended only by hard scales
or plates (squameé and scute); but the warm-
blooded classes require to be invested by an
integument better adapted to maintain the high
degree of temperature peculiar to them: hence
quadrupeds are clothed with fur and hair, and
birds with down and feathers.

Feathers are the most complicated of all
the modifications of the epidermic system,
and are quite peculiar to the class of birds.
The eloquent Paley well observes that “ every

* Mr. Swainson objects to the theory which
ascribes to the serrated claw the function of freeing
the plumage from vermin, because its presence is
partial in the class of Birds. ‘‘ To suppose,” says
he, ‘* that nature has given to one or two families
of birds the exclusive power of freeing themselves
from an enemy which in like manner infests all
birds, is preposterous.” The assertion that the
different species of Nirmi infest all birds in like
manner is much easier than the proof.

+ In one section of the Tyranni, Cuv. the scute
surround the tarsi as complete rings. Where the
carneous parts of the muscles are continued low
down upon the legs, as in the Owls, a covering of
feathers is co-extended to preserve their tempera-
ture,

350

feather is a mechanical wonder ;” “ their dis-
position, all ‘inclined backward, the down
about the stem, the overlapping of their tips,
their different configuration in different parts,
not to mention the variety of their colours,
constitute a vestment for the body, so beau-
tiful, and so appropriate to the life which
the animal is to lead, as that, I think, we
should have had no conception of any thing
equally perfect, if we had never seen it, or
can now imagine any thing more so.”
Notwithstand-
ing the varieties
of size, consis-

tence,and colour, *iudy
all feathers are Sy I,
composed of a 5 4
guill or barrel Ly i
(a, fig. 177), a Ly
shaft (b b), and Af),
a vane or beard hip /;
(cc); the vane A by
consists of barbs Zh
(e e, fig. 178) te
and barbules(ff, J,
fig. 178). 4
The gull, by Vy
which the feather as:
is attached to the Wy
skin, is larger WQQ\\\ oJ
and shorter than Wy
the shaft, is near- fy

ly cylindrical in
form and. semi-
transparent; it
possesses in an
eminent degree
the opposite qua-
lities of strength
andlightness. It
terminates below
in a more or less
obtuse extremity,
which is pierced
by an_ orifice
termed the lower
umbilicus (e, fig. 5
177); a second @-¢
orifice, leading into the interior of the quill,
is situated at the opposite end, at the point at
which the two lateral series of barbs meet and
unite; this is termed the upper umbilicus (f,
Jig. 177). The cavity of the quill contains a series
of conical capsules fitted one upon the other, and
united together by a central pedicle.

The shaft is more or less quadrilateral, and
gradually diminishes in size from the upper
umbilicus to its distal extremity. It is always
slightly bent, and the concave side is divided
into two surfaces by a middle longitudinal
line continued from the upper umbilicus ; this
is the internal surface (c, fig. 178). The
opposite, or external surface (b, fig. 178), is
smooth, and slightly rounded; both sides are
covered with a horny material similar to that

* This figure and fig. 179, 180, 181, are copied
from the Monograph of F.Cuvier, ‘‘ Surle developpe-
ment des Plumes,” Mémoires du Muséum, tom. xiii.

AVES.

of which the quill is formed, and they inclose
a peculiar white, soft, elastic substance, called

|
{|
Wil |
|
| |
1] WH
Wi
ii} WT
Hi
{| | H
WHI |
| |
WD
| }
HTH
HW

Section of the Shaft and Vane magnified.

The barbs are attached to the sides of the
shaft near the external surface, and consist of
lamine, varying as to thickness, breadth, and
length. They are arranged with their flat sides
towards each other, and their margins in the
direction of the external and internal sides of
the feather; consequently they present a con-
siderable resistance to being bent out of their
plane, although readily yielding to any force
acting upon them in the line of the stem: ¢ ¢,
fig. 178, are the bases of the barbs of a
feather magnified. The barbules (f f, fig.
178) are given off from either side of the barbs,
and are sometimes similarly barbed themselves,
as may be seen in the barbules of the great
feathers of the Peacock’s tail.

Sometimes, as in these feathers and in the
plumes of the Ostrich, the barbules are long
and loose; but more commonly they are short
and close-set, and by their form and disposition
constitute the mechanism by which the barbs
are united together. The barbules arising from
the upper side of the barb, or that next the
extremity of the feather, are curved downwards
or towards the internal surface of the shaft ;
those which arise from the under side of the
barb are curved in the contrary direction: so that
the two adjoining series of hooked barbules lock
into one another in a manner which the Pari-
sian dissectors compare to the fastening of a
latch of a door into the catch of the door-post.

But besides the parts which constitute the
perfect feather, there is also an appendage
attached to the upper umbilicus of the quill
which requires to be noticed. This is termed
the accessory plume. It is usually a small
downy tuft, but varies both in different species,
and even in the feathers of different parts of
the body of the same bird. In the quill-
feathers of the wings and tail, it usually
remains in the rudimentary state of a small
tuft of down; but in the body-feathers of
Hawks, Grouse, Ducks, Gulls, &c. it is to
be found of all sizes, acquiring in some species
a size equal to that of the feather from which
it is produced.

* Perrault, Hist. Nat. des Animaux, p. 336.

AVES.

In the Ostrich the feathers have no accessory
plume: in the Rhea it is represented by a tuft
of down; in the Emeu, on the contrary, the
accessory plume equals the original feather, so
that the quill supports two shafts; and in the
Cassowary, besides the double feather, there
is also a second accessory plume, so that
the quill supports three distinct shafts and
vanes.

The feathers vary in form in different parts
of the bird according to their functions, and
afford zoological characters for the distinction
of species; they have, therefore, received in
Ornithology distinct names. Those which
surround or cover the external opening of the
ear are termed ‘ auriculars.’ ose which
lie above the scapula and humerus are
called the ‘ scapulars.’ The small feathers
which lie in several rows upon the bones of
the antibrachium are called the ‘lesser coverts’
(tectrices prime). Those which line the under
or inner side of the wings are the ‘ under
coverts.’ The feathers which lie immediately
over the quill-feathers are the ‘ greater coverts’
(tectrices secunde ). The largest quill-feathers
of the wing, which arise from the bones of
the hand, are termed ‘ primaries’ (primores ).
Those which rise from the ulna, towards its
distal end, are the ‘ secondaries’ (secondarie ).
Those which are attached to its proximal ex-
tremity are the ‘ tertiaries’ (tertiarie). These
in some birds, as the Woodcock and Snipe,
are so long as to give them the appearance,
when flying, of having four wings. The
quill-feathers which grow from the phalanx,
representing the thumb, form what is termed
the bastard wing (alula spuria ).

In considering the structures which deter-
mine the powers of flight in different birds,
it is necessary to take into account the structure,
forms, and proportions of the wing-feathers,
as well as the development of the bones and
muscles which support and move them; as
much depends upon the mechanical advantages
resulting from the shape and texture of the
expanded wing. When the primary quill-
feathers gradually increase in length as they
are situated nearer the extremity of the pinion,
they give rise to the acuminated form of wing,
as in the true Falcons, in which the second
primary is the longest. In the Hawks the
wing is of a less advantageous form, in con-
sequence of the fourth primary being the
longest ; when the primaries gradually decrease
in length towards the end of the pinion, they
give rise to a short rounded form of wing,
such as characterizes the Gallinaceous Order;
in which, although the pectoral muscles are
immensely developed in order to counteract
the disadvantage resulting from the disposition
of the primaries, yet they are only able, in
consequence of the form of the wing, to carry
the bird rapidly forward for a short distance,
and that with an exertion and vibratory noise
well known to every sportsman.

The texture of the quill-feathers has also a
material effect on the powers of flight. In
the Falcons each primary quill-feather is
elongated, narrow, and gradually tapers to a
point; the webs are entire, and the barbs

351

closely and firmly connected together.* In
the Owls the plumage is.loose and soft, and
the outer edge of the primaries is serrated ;
so that, while they are debarred from a rapid
flight, which would be dangerous in the gloom
in which they go abroad, they are enabled, by
the same mechanism, to wing their way without
noise, and steal unheard upon their ee

Development of feathers —The first covering
of the bird is a partial and temporary one,
consisting of fasciculi of long filaments of
down, which on their first appearance are en-
veloped in a thin sheath, but this soon crumbles
away after being exposed to the atmosphere.
The down-fasciculi, which diverge each from
a small quill, are succeeded by the fea-.
thers, which they guide, as it were, through
the skin: and after the first plumage, at each
succeeding moult, the old feathers serve as
the gubernacula to those which are to follow.
It is to be observed that feathers do not grow
equally from every part of a surface of a bird ;
they are not developed, for example, at those
parts which are subject to friction from the
movements of the wings and legs. They
first appear in clumps upon those parts of the
skin which is least affected by the pressure of
superincumbent parts, or the movement of the
parts beneath, as upon the head, along the
Spine, upon the exterior surface of the extre-
mities, at the intervals of the joints on either
side the projecting sternum, and at the sides
of the abdomen.

The matrix, or organ by
which the perfect feather is
produced, has the form of an
elongated cylindrical cone,
and consists of a capsule, a
bulb, and intermediate mem-
branes which mould the secre-
tion of the bulb into its ap-
propriate form. The matrix
is at firstan extremely minute
cone, attached by a filamen-
tary process to a follicle or Wai
papilla of the skin; but it is Wa
not a development of that NA
part, being of a different |i YING |
structure and adhering to it | TN
by asmall part only of ts | ‘A

Fig..179.

"

ii

|

circumference. The matrix
piogronively increases in
ength ; its base sinking deep-
ly into the corium, and ac-
quiring a more extended con-
nection by enlarged vessels
and nerves, while its apex
protrudes to a greater or less
extent from the surface of the
integument, when the cap-
sule drops off to give passage
to the feather which it incloses, ing Feather, with
and the formation of which the Capsule laid
has, in the meanwhile, been open.

=e

4

|
|
il
i
i
|

|

Mt

|

}
Ht
Hit
iH

|

|

1

Matrix of a grow-

* Of so much consequence are the quill-feathers
to the Falcons, that when any of them are broken
the flight is injured and the falconers find it ne-
cessary to repair them ; for this purpose they are
always provided with perfect pinion and tail fea-
thers, regularly numbered, :

352

dually proceeding from the apex downwards.

e capsule of the matrix (aa, fig. 179) is
composed of several layers, the outermost of
which is of the nature of epidermis ; the inner
ones are more compact, but have no appear-
ance of organization. The sides of the cap-
sule which correspond to the outer and inner
sides of the growing feather within are indi-
cated by a white longitudinal line.

The axis of the capsule is occupied by a
medulla or bulb, (e, fig. 179,) also of a cy-
lindrical form, and of a soft fibrous texture,
adhering by its base to the parts beneath, and
there receiving numerous bloodvessels and a
nerve.

Between the medulla and the capsule
there are two parallel membranes, one in-
ternal (d, fig. 179); the other external,
(b, fig. 179); from the latter membrane a
number of close-set parallel laminz extend
obliquely from one of the white longitudinal
lines above mentioned to the other on the
opposite side of the cylinder. The two mem-
branes seem to be united together by the
oblique septa. In the long and narrow spaces
between these septe, the matter of the vane
(c. fig. 179) is deposited, and formed into
barbs and barbules, nearly in the same way as
the enamel of the teeth is formed between the
external membrane of the pulp, and the in-
ternal membrane of the capsule. The depo-
sition of the material of the barbs commences
at the apex of the bulb, and the stem is next
formed in the following manner.

The external longitudinal line from which
the oblique laminz are continued, receives and
moulds on the inner surface of the external
capsule the horny covering of the back of the
feather, or that longitudinal band, to the two
sides of which the barbs are attached ; and on
the opposite surface of the internal membrane
are formed the pith or substance of the shaft,
and the horny pellicle which incloses it on the
inner surface. The internal longitudinal line
has no other use than to establish a solution
of continuity between the extremities of the
barbs of one side and those of the other, which
meet at that part, and thus curve round and
completely inclose the formative bulb. In
fig. 180, the capsule of the matrix of a grow-
ing feather has been laid open, and the nascent
barbs (c) which surrounded the bulb have been
unfolded, exposing that part at a 6. A portion
of the barbs and stem have been completed
and protruded, and the bulb is beginning to
undergo a process of absorption at that part,
which will hereafter be described. The shaft
and harbs at the apex of the cylinder are the
first parts which acquire consistence, and the
molecules composing the remainder are less
compactly aggregated as they are situated
nearer the base of the matrix. As the gela-
tinous medulla increases at the base, the first-
formed shaft and barbs are protruded through
. the extremity of the capsule, the bulb con-
tinuing to furnish the secretion whichis moulded
between the two striated membranes until the
entire feather is completed. If the striated
membrane inclosing the bulb be attempted to

AVES.

Fig. 180.

Structure of the Bulb.

be reflected from below upwards, it will be
found to be connected with a series of mem-
branous cones (a 6 cd e, fig. 181,) ranged one
upon the other throughout the whole length of
the bulb, and connected together by a tube
running through its centre. In this figure
(181) the pulpy matter which occupied the
interspaces of the cones has been removed to
shew their central connecting tube.

As the development of the feather advances,
the pulpy matter disappears from the summit
of the medulla, and only the membranous
funnel-shaped caps remain, which are pro-
truded from the theca and the centre of the
new-formed barbs, and fall off as these ex-
pand. The theca which incloses the whole
is of a firm texture where the new moulded
barbs are yet pulpy and tender, but it be-
comes thinner as these acquire consistency,
and lastly, dries and crumbles away after it
has been exposed to the action of the atmos-
phere. The bulb itself, when examined in a
half-formed quill-feather,* is composed of two
parts corresponding to the external and in-
ternal aspects of the feather. The internal
part represents a semi-cylinder or case, in-

* The following description is taken from such a
feather in the goose. 4 ;

To. &

ee

AVES. 353

closing the external part, which is of a conical
form ; the latter extends from the base of the
bulb, and gradually diminishes to a point
where the shaft is completed and the barbs
begin to expand. Its office is to deposit the
pith within the shaft, and it is absorbed in
proportion as this is effected. The internal
part or case also commences at the base of the
bulb, and adheres closely to the cone, with
which, indeed, its substance is continuous; it
increases in thickness as the cone diminishes,
its margins are beautifully scolloped or crenate,
and the crenations are lodged in the interspaces
of the oblique lamine or moulds, and deposit
in them the material of the vane. The horny
sides of the shaft are lodged and formed in the
grooves between the external and internal parts
of the bulb, and correspond in degree of
formation to the depths of those grooves, and
being progressively brought into contact from
above downwards, the shaft is thus completed,
leaving the longitudinal line at the internal
side. When all the grooves, (wherein are
formed the barbs, and the portion of the shaft
which carries them) are filled by the horny
matter, and the barbed part of the feather is
finished, this horny matter lastly expands uni-
formly around the medulla, and forms the quill
of the feather.

When the quill of the feather has acquired

the due consistence, the internal medulla be-

comes dried up, and is resolved, as before, into
membranous cones arranged one upon the
other ; but these latter never pass out, for the
quill, which is now hardened and closed by
the shaft at the opposite extremity to the lower
umbilicus, will not permit their egress ; they
remain, therefore, inclosed, and constitute the
light dry pith which is found in the interior of
the quill. The last remains of the bulb are seen
in the ligament which passes from the pith
through the lower opening of the quill and
attaches it to the skin.

Cuvier has justly observed that notwith-
standing the complexity of the process just de-
scribed, the formation of a feather differs only
from that of a tooth in the nature of the substance
which is deposited between the two tunics
which constitute its mould; but a tooth takes
many years to be perfected, and there are but
two series produced in one part of the jaw, and
only one in the other, in any warm-blooded
animal, Feathers, on the other hand, are de-
veloped in the course of some days; they
attain a length of from one to two feet or more
in many birds, and they are almost all re-
newed every year,—in many species even twice
a year. It may be conceived, then, how much
vital energy the organization of birds must
exercise, and how many dangers must accom-
a so critical a period as that of the moult.

_ The plumage is commonly changed several
times before it attains that state which is re-
egr as characteristic of the adult bird.

e time required for this varies from one to
five years, and several birds rear a progeny
before they acquire the plumage of maturity.

When the male bird assumes a vestment
VOL. I.

differing in colour from the female, the young
birds of both sexes resemble the latter in their
first plumage ; but when the adult male and
female are of the same colour, the young have
then a plumage peculiar to themselves. Mr.
Yarrell states a third law in addition to the
preceding, viz. that whenever adult birds as-
sume a plumage during the breeding season
decidedly different in colour from that which
they bear in winter, the young birds have a
plumage intermediate in the general tone of its
colour compared with the two periodical states
of the parent birds, and bearing also indica-
tions of the colours to be afterwards attained
at either period.

“There are three modes,” the same author
observes, “ by which changes in the appearance
of the plumage of birds are produced :—

‘« By the feather itself becoming altered in
colour.

“¢ By the bird’s obtaining a certain number
of new feathers without shedding any of the
old ones ; and

“¢ By an entire or partial moulting, at which
old feathers are thrown off and new ones pro-
duced in their places.

“ The first two of these changes are ob-
served in adult birds at the end of spring, in-
dicating the approach of the breeding season ;
the third change is partial in spring and entire
in autumn.

“¢ A fourth mode may be noticed, though
its effects are limited. It is observable in
spring, as the breeding season approaches, by
the wearing off of the lengthened lighter-
coloured tips of the barbs of the feathers on
the body, by which the brighter tints of the
plumage underneath are exposed, as was no-
ticed by Sir William Jardine and Mr. Blyth.
The effect is most conspicuous in the Buntings,
Finches, and Warblers.”*

The experiments detailed in the Memoir
above quoted, some of which we witnessed,
prove incontestably, that notwithstanding the
extravascular nature of feathers, they are
subject to influences, apparently of a vital
nature, which occasion a change of colour in
them after they are completely formed. In
yearling birds the winter plumage which suc-
ceeds the autumnal moult gradually assumes
the brighter tints characteristic of the adult
without a change of feather. The new colour
commences generally at that part of the web
nearest the body of the bird, and gradually
extends outwards till it pervades the whole
feather.

Organs of generation.— The few varieties
of structure which these organs present in the
Class of Birds, are principally met with in
those of the male, which we shall first de-
scribe.

The male organs of generation exhibit all
the essential characteristics of the oviparous
type of structure. The testes are situated high
up in the abdomen, whence they never descend
into an external scrotum. The intromittent

* Yarrell, Zool. Trans. i. p. 13.
2A

354

organ is either double, as in Serpents, when,
however, each penis is extremely small; or it
is single, but in this case, to whatever extent
it may be developed, it always consists of a
uniform ligamentous and vascular elastic sub-
stance, and, as in the Tortoise, is simply
grooved along the upper surface or dorsum for
the passage of the fecundating fluid. —

As there is no true urethral canal, so neither
are the glands of Cowper or the prostatic
glands present.

The testes (2, fig. 166,
a, a, fig. 182) are two in
number; in form more or
less oval, situated above
the upper extremities of
the kidneys. They vary
remarkably in colour in
different birds; we may
mention, as examples,
that they are white in
the Peregrine Falcon and
and Dove; pale yellow
in the Horn-Owl, and
Gallinule ; of a brighter
yellow in the Magpie,
Bay Ibis, Ruff, and Oys-
ter-catcher ; of a black
colour in the Chough,
Partridge, Heron, Sea-
gull, but whitish towards
the lower end in the last
two. They are invested
with a strong and dense
albuginean tunic. Their
structure is evidently tu-
bular, the contorted tu-
bules are very slender,
scarcely exceeding in di-
ameter the seminal tu- Urinary and male organs
bules of mammalia: they of a Cock.
are separated into packets by delicate and mem-
branous septa, continued from the inner surface
of the tunica albuginea.

The arteries spread in an arborescent form
beneath that capsule. The vas deferens (c c)
is continued from the posterior and internal
part of the gland.

The periodical variations of size which the
testicles undergo are very remarkable in the
Class of Birds; and the limited period during
which their function is in activity is compen-
sated by the frequency and energy with which
it is exercised.

The proportional size which the testes ac-
quire at the breeding season is immense, as may
be seen in the subjoined figures (183) of the
testes of the House-Sparrow ;* which commences
with the glands as they appear in January,
when they are no bigger than pins’ heads, and
ends with their full development in April.

It rarely happens that both testes are deve-
loped in exactly the same degree, but the
increase of size is not limited to the one on
the left side. The right testis is as often the

* See John Hunter, in the Animal (Economy,
plate vii.

AVES.

—

. January.

2. Middle of February.

ee)

. Beginning of March.

4. Latter end of March.

5. Middle of April. —

Testes of the House-Sparrow.

largest, and we have seen an example, in a
Rook, where it alone had taken on the action
of sexual increase, and had acquired a bulk
compensating for the want of development in
the left testis.

In most Birds, the only appearance of an
epididymis is a remnant of the Wolffian body
or primordial matrix of the genital and urmary
organs (6, fig. 182). This part frequently pre-
sents a colour strikingly different from that
of the testes: thus it has been observed in
the Bustard and Curassow to be black; in the
Cassowary, yellow; and in the Anthropoides
Virgo to be of a green colour. —

In the Ostrich the epididymis is folded upon
itself at the side of the testis.

The vas deferens commonly passes down
to the cloaca by the side of the ureters
without undergoing any remarkable convo-
lution ; but in the common Cock it is bent
upon itself in short transverse folds from side
to side almost from its commencement; the
folds gradually but slightly increase as they
approach the cloaca, both in extent and in the
diameter of the tube composing them, and
they are so closely compacted as to present in
a longitudinal section the appearance of a
series of cells, which are capable of retaining,
as in a vesicula seminalis, a quantity of the
seminal secretion.

Each vas deferens in the Common Cock
terminates on a separate rudimentary penis or
papilla, situated in the urethro-sexual division
of the cloaca at a little distance from each

other, and anterior to, or sternad of the inser-

tions of the ureters.

remarkable plexus of arteries and veins (
Jig. 171) which serve as an erectile organ

The base of each bs par is surrounded ee E
* M,

the venereal orgasm, when the turgid papillz are

4

—— ae

>

= §

+ ee

AVES.

everted, and the semen brought into contact with
the similarly everted orifice of the oviduct in the
female, along which the fecundating fluid is
impelled by the vibrations of the cilia of the
mucous surface through all the windings of
that tube to its ultimate destination.

In the Natatores which copulate in water
there is an obvious necessity for a more effici-
ent coitus than a simple contact of everted
cloace, and consequently in these birds, as the
Swan, Gander, Drake, &c. a long, single penis
is developed.

Fig. 184.

Mr

trem

ae

; 8
Lf
i
a
2
CI
s
Z
»
“li
-
=
=
ss
bs]
=
\
=
~~
=
=
jis
a
=
i‘
=
‘i
z
| ee
2
g

Penis of a Drake.

This body arises from the front part of the
outer compartment of the cloaca (a, a, fig. 184)
immediately below the urethro-sexual cavity ;

355

it is in the unexcited state coiled up like a
screw from the elasticity of the internal liga-
mentous structure. The external coat is a pro-
duction of the membrane lining the outer
cavity, and gives off a number of small pointed
processes, which in the Gander are arranged in
transverse rows on either side the urethral
groove, and near the extremity of the penis are
inclined backwards. The body (0 b, fig. 184,
where it has been cut open) is composed of a
white elastic ligamentous substance, and a
vascular pulp, but without any of the cellular
structure which characterizes a corpus caver-
nosum. A groove (dd), commencing widely
at the base is continued along the side of the
ligamentous substance, and follows all the
spiral turns of the penis to its extremity.
The vasa deferentia terminate in papille at
the base of this groove, along which the semen
is transmitted to the vagina of the female.*

The penis of the Ostrich is also single, and
the urethra is represented by a dorsal groove ;
it is disposed in a slight spiral bend when in a
retracted state. It arises by two strong liga-
mentous crura from the cartilage uniting the
bones of the pubis, and descends into the
external or preputial compartment of the
cloaca. There are four muscles to the penis
of the Ostrich : two arise from the inside of the
os sacrum, and descending along the preputial
cavity, are inserted into the base of the penis:
two other muscles pass from the internal part
of the iliac bones, to be attached to the sides
of the penis.

The Guan (Penelope cristata) presents a
singular exception to the other Rasorial Birds
in having a single linguiform pointed penis
developed, the sides of which are provided
with retroverted papille, as in the Anserine
Birds. In the Gallinule, which seeks its food
in water, there is no penis ; it, therefore, most
probably copulates on land.

The tumid margin of the preputial cavity
of the penis is well provided with large mu-
cous follicles which secrete a sebaceous lubri-
cating substance ; of these there are twelve in
the Gander, arranged six on each side. These
may be regarded as analogous to the glandule
odorifere ; but there is no vestige either of
prostatic or other urethral glands.

Female organs of generation.—An ovarium
or productive organ, (a, b, c, d, fig. 185,) with
an oviduct or efferent tube (e, f, g, k, /,) are
present in all birds, and a clitoris or organ of

* We cannot account for the error into which
Sir Everard Home has fallen, in describing the
urethra of the drake as a complete canal, and the
penis as being enclosed within a prepuce. (Phil.
Trans. 1802, pp. 361, 363.) Repeated dissections
of different specics of Anas, Cuv. have satisfied
us of the accuracy of Mr. Hunter’s statement,
that “‘ birds have no urethra, some having merely
a groove, as the Drake and Gander, and many
being even without a groove, as the common Fowl.”
Animal GEconomy, p. 40. The letter ¢, in Sir
Everard Home’s figure, (fig. 184,) points to the
orifices of mucous glands or cut vessels, and not to
the papille, on which the vasa deferentia termi-

nate.
a 2

356

excitement is found in those species of which
the males have a penis.

Birds differ from ali the other oviparous
vertebrata in having the canal which completes
and carries out the ovum single, and in this
respect they manifest an analogy to many
mammalia. When, however, the whole of the
circumstances from which this condition re-
sults come to be investigated, the nature of the
_part in the two classes will be found to be
widely different.

In the Mammalia the single efferent canal
results from a blending together of the vaginz
and uteri of the two sides of the body fora
greater or less extent along the mesial line;
which junction is continued from the external
outlet towards the ovaria, but never extends
beyond the uteri, the Fallopian tubes always
remaining distinct. And in proportion as the
generation approximates the oviparous mode,
the efferent tubes remain separate for a greater
extent. Thus, among the Rodentia, we find
the uterus completely divided into two lateral
tubes, as in the Rabbit; and in the Marsupiata
the division is continued through the whole
extent of the true vagina.

In the true Oviparous classes the oviducts
are always double and open separately into the
cloaca, and the exception in the class of Birds
to this rule is only apparent.

At an early period of existence the two
oviducts exist of equal size, but the left one
alone attains that state of development which
qualifies it for the exercise of the sexual func-
tions. Hitherto no exception has been found

* This figure, and those numbered 133, 134, 135,
136, 138, 151, 153, 163, 182, are copied from the
plates of the second edition of Carus’s ‘ Verglei-
chenden Zootomie.’

Soma

"EY oe

gf eh

4 ani
yy

AVES.

to this rule, and the uniformity in the condition
of the excluded ovum in Birds corresponds with
the sameness which prevails in the structure of
the organs concerned in its evolution. 4

The ovarium is in general single like the
oviduct, and developed only on the left side,
as in the Rasores. But two ovaria have been
observed in many of the Raptores. In the
Falcons Nirzscn found the right ovary more
developed than the left, and also in some
species of Eagle and Owl. In the Sparrow-
Hawk the same distinguished anatomist found
two ovaries equally well developed.

In the Common Fowl] the ovary first makes
its appearance as a membrane beset with small
pellucid vesicles adhering to and apparently
developed from the coats of the vena cava.
The substance of the ovary is invested by a
thin and extensible capsula propria, covered
by a reflection of peritoneum. The ova are
imbedded in a stroma of delicate and yielding
cellular substance, and consist each of a mi-
nute pellucid vesicle, surrounded by the yolk,
which at this period is as clear as the fluid of
the vesicle itself, and both are inclosed ina
distinct transparent capsule. |

When the ovum has attained the diameter
of a line, the vitelline liquid presents a turbid
whitish appearance. When it is about the size
of a pea the yolk begins to assume a slight
straw-coloured tint, and the seat of this colour-
ing matter may be observed to be certain glo-
bules of oil now superadded to the albuminous
and serous fluid. As the oily material prevails,
the yolk gradually assumes a more viscid and
tenaceous consistency, and a deeper and deeper
tint, until it presents the rich orange colour
characteristic of the mature ovarian ovum.

If one of these ova be transversely divided
after being hard-boiled, the cut surfaces of the
yolk will present three concentric strata of diffe-
rent colours; the external one is of a pale straw
colour, the middle one of a deeper yellow,
and the internal one is again light-coloured,
and surrounds a substance of a whitish colour
and more fluid consistency, from which a canal
surrounded by a similar substance is continued
to the cicatricula. The central substance and
continuous canal are composed of albuminous
fluid containing white granules, similar to the
colliquamentum of the cicatricula.

The primitive vesicle of the ovum around
which the material of the yolk is accumulated, |
by no means grows with the growth of the
ovum; it is not more than one-half larger in
the largest ovarian ovum, than it was when
the ovum exhibited its smallest dimensions,
and when the vesicle formed its most con-
siderable part. Throughout the whole of this
period it is, however, the most important
of the ovarian ovum; forming the essential —
element of the cicatricula, and the centre from —
which all subsequent development radiates.

Purkingé, the discoverer of the ‘ germinative —
vesicle,’ states that it is most easily detected —
in the ova of the common Fowl, when they —
have attained the size of from four to six lines. —
The vesicle is at this period lodged in a mam-

AVES.

millary pile (cumulus) of white granular sub-
stance, which is surrounded by a whitish zone,
and is continuous with the granular stratum
applied to the internal surface of the membrana
vitelli, but not adherent to that membrane.

e€ common envelope of the germinal vesi-
cle, cicratricula, and yolk, is called the mem-
brana vitelli. It is extremely delicate and
transparent, without any perceptible organi-
zation, and forms an entire or shut sac. It is
at first scarcely distinguishable from the stra-
tum of granules forming the periphery of the
yolk, and at this period the germinal vesicle
closely adheres to it. Subsequently, however,
@ separation is effected by an interposed stra-
tum of granules. The external membranes of
the ova are thick in proportion to the vitelline
membrane, and can with difficulty be detached
from without lacerating it.

The part of the ovary in which the ovum is
lodged is termed the calyx (a, d, fig. 185).
It consists of two membranes; the external
one is highly vascular; the internal one is
somewhat smooth and pellucid, and is beset
with equidistant, minute, and apparently glan-
dular bodies.

As the ovarian ovum advances to maturity,
a pedicle is developed from which the calyx
with its contained ovum depends, and which
permits it to be brought in contact with the
infundibular orifice of the oviduct (e, fig. 185).

The external vascular tunic of the calyx
then becomes covered with a rich profusion
of vascular twigs (6, fig. 185) distributed in a
pectinated manner, and converging towards a
white transverse line, called the stigma (c,
Jig. 185). This stigma begins to appear when
the ova have attained the diameter of an inch,
in the form of a whitish streak, which con-
tinues to increase in breadth, and the
membranes at that part to be thinned by
absorption until they readily yield, and are
rent by the compressing force of the infun-
dibular opening of the oviduct, when the
Ovarian Ovum escapes, and is received into the
efferent passage.

The membrana vitelli is at this period
sufficiently strong and ductile to permit the
ovum bemg compressed into an_ elliptical
form to facilitate its passage through the con-
tracted part of the oviduct (/)), but during
this process Purkingé conjectures that the
germinal vesicle of the cicatricula is ruptured
and its pellucid contents diffused. It is
certain at least that it can no longer be de-
tected either in the cicatricula of the ovum of
the oviduct, or in that of the excluded egg.
The further changes which take place in the
generative product, now no longer forming a

rt of the maternal system, will be described
in the article Generation; and we resume
the consideration of the female organs.

The calyx of the ovum, when emptied of its
contents (d, fig. 185) collapses, shrinks, and is
ultimately absorbed, not forming a permanent
se luteum, as in Mammalia.

’ In Birds that have but few young at a brood,
as the Eagles or Doves, the number of enlarged

357

yolks is ‘asi a sporpen ss small; but in the more
prolific species, as the Common Fowl, they are
more numerous. The number of young pro-
duced may be, by this means, in some degree
inferred, if the female of a rare species happen
to be killed during the breeding season.

The oviduct commences by the infundibular
orifice, where its parietes are very thin; as it
descends, these increase in thickness, and the
efferent tube gradually acquires the texture and
form of an intestine. Like this, it is attached
to and supported by a duplicature of perito-
neum called the mesometrium, but which also
includes muscular fibres, to be presently de-
scribed.

The oviduct in the quiescent state is generally
straight, but at the period of sexual excitement
it is augmented in length as well as capacity,
and describes three principal convolutions be-
fore reaching the cloaca. The lining membrane
presents a different character in different parts
of the oviduct; at the infundibular extremity it
is something like the mucous coat of the intes-
tine, then it becomes rugous, and afterwards,
at the part where the egg is detained and the
chorion calcified, it presents a number of long
close-set villi (k, fig. 185). This part is by
some anatomists termed the uterus, but by a
loose analogy, as the ovum is developed out
of the body of the parent. The rest of the
canal, which, pari modo, is termed vagina,
opens into the urethro-sexual segment of the
cloaca, anterior to the termination of the left
ureter, and its termination (f, fig. 164, 176)
is provided with a sphincter.

e mesometry (m, fig. 185) differs most
from the mesentery when the female organs are
in full sexual action. It presents at that period
a true muscular structure. It is divided into
two parts, one superior, the other inferior.
The inferior mesometry has its point of attach-
ment at the lower part of the uterine portion
of the oviduct, and forms a somewhat dense
and cruciform plexus of muscular fibres ra-
diating from that part. The transverse fasci-
culi are spread out on either side and around
the uterus. The lower fasciculus surrounds
the vagina more laxly, and contributes to the
expulsion of the ovum. The upper fasciculus
spreads out like a fan upon the oviduct from
its insertion into the uterine portion to the com-
mencement of the infundibulum.

The superior mesometry commences by a
firm elastic ligament, which is attached to the
root of the penultimate rib of the left side,
whence the muscular fibres are continued to
the upper part of the oviduct, upon which
they form a delicate muscular tunic, whose
fibres embrace the oviduct for the most part
in the transverse or circular direction, except
at the infundibular aperture, where they affect
the longitudinal direction, which enables them
to dilate that orifice. Longitudinal muscular
fibres begin again to be distinctly seen in the
uterine portion of the oviduct, whence they are
continued along the so-called vagina. An in-
ternal stratum of circular fibres is also situ-

ated immediately behind the calcifying mem-

358

brane of the uterus. In the vagina the circular
fibres are concentrated at its termination to
form the sphincter above mentioned.*

The clitoris in the Ostrich is continued from
the anterior margin of the preputial cavity of
the cloaca, and is grooved like the penis of the
male; it has also the same muscles inserted
in it. A corresponding projection, as before
observed, is met with in those birds of which
the males have a well developed intromittent

organ.

BIBLIOGRAPHY.—Perrault, Description Anato-
mique de six oiseaux appellés Demoiselles de
Numidie, Mém. de Paris, t.i. et t. iii. Duverney,
Observation Anatomique sur le perroquet arras,
sur la cigogne, sur le casuel, Mém. de Paris, t. i.
Vicg-d’Azyr, Mémoires pour servir a l’anatomie
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Tiedemann, Zoologie, 2ter u. 3tter Bd. Anat. und
Naturgeschichte d. Vogel, 8vo. Landsh. 1808-14.
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Vogel, 8vo. Leipz. 1811. * * * * Herissant,
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De Reaumur, Sur la digestion des oiseaux, Mém,
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Untersuchungen tiber das Schlagadersystem d.Vogel,
Meckel’s Archiv. Jahrg. 1828. Monro, State of
facts, &c. and on the lymphatic vessels of oviparous
animals, Edin. 1770. Hunter on the absorbents
of Birds, in Phil. Trans. 1768. Hewson on the
absorbents of Birds, Phil. Trans. 1769. Lauth,
Mém. sur les vaissaux lymphatiques des oiseaux,
Ann. des Sciences Nat. 1825. * * * * Daubenton,
Observations sur la disposition de la trachée-
artere de differentes espéces.d’oiseaux, Mém. de
Paris, A. 1781. Latham, Essay on the trachee,
or windpipes, of various kinds of birds, Linn,
Trans. v.iv. Fuld, De organis quibus aves spiritus
ducunt, 4to. Wirceb. 1816. Yarrell on the trachea
of Birds, in Linn. Trans, 1827. Hunter, An
account of certain receptacles of air, in birds, which
communicate with the lungs, and are lodged both
among the fleshy parts and in the hollow bones of
these animals, Phil. Trans. Y. 1774. * * * *
Haller, De cerebro avium et piscium, Verh. van
het Maatsch. te Haarlem, Deel 10. Malacarne,
Esposizione anatomica delle parti relative all’en-
cefalo degli uccelli, Mem. de Verona, t. i, ii. iii. iv.
vi. vii. Nwman, De medulla spinali avium, &c.
Svo. Halle, 1811. Frank, De avium encephali
anatome, 8vo. Berl. 1812, et in Reil’s Archiv.
Bxi. * * * * Vicgq-d’Azyr, De la structure de
l’organe de l’ouie des oiseaux, Mem. de Paris, A.
1778. * * * * Mery, Observation sur le cercle
osseux autour de la cornée de l’eil de l’aigle, du
corbeau, et sur la sclerotique de V’autruche, Mém.
de Paris, t. ii. p. 24. Tamnnenberg, De partibus
genitalibus masculis avium, 4to. Gotting. 1789;
Germanice auct, 4to. Gotting. 1810. Spangenberg,
Disq. circa gas foemineas genitales avium, 4to.
jane 1813. Cuvier, Lecons d’Anat, Comparée,
5 vol. 8vo. passim.

Rees’s Cyclopedia, art. BIRDS,
by Macariney,

( Richard Owen.)

* Purkinjé, Symbole ad Ovi Avium Historiam,
4to. 10. fig. 19.

AXILLA.

AXILLA (surgical anatomy)—(Fr. Aisselle,
Ger. Achselgrube.) Syn. region aaillaire, Velp.
is the Latin name for the armpit, and is used
by anatomists to designate an important.region
situated between the upper extremity and the
thorax.

The axilla in man is the séat of so many
diseases and accidents; it contains so large a
number of nerves, arteries, and lymphatic
glands; and is so frequently interested in sur-
gical operations, that a pretty full description
of it is allowable on the present occasion.

When the arm is separated a little from the
side, we observe, in the angle between them, a
hollow space, which, in the adult, is always
covered with hair. This is, in popular lan-
guage, the armpit; but to the anatomist the
term axilla conveys a very different notion.
By him it is understood to mean a large region,
bounded anteriorly by the greater and lesser
pectoral muscles, posteriorly by the subsca-
pular, the teres major, and a part of the latis-
simus dorsi, and internally by the ribs, the
intercostal muscles, and the serratus magnus.
It presents a basis below, formed of skin and
fascia, and an apex above, which opens into the
cervical region between the clavicle, scapula,
and first rib. Its walls form, therefore, a kind
of triangular pyramid, very unequal in their
extent, very irregular, and continually under-
going alterations in size and shape. Its height
is greater in the male than in the female, but
its other dimensions are neatly equal. It is
to be found in all animals which have an upper
extremity, and its uses are subservient to the
motions of that limb.

In the following description the adult male
axilla is always supposed to be meant unless
otherwise specified,

When the arm is raised to the horizontal —
position, we see the floor of this region, the
base of our pyramid. This floor is triangular,
having its truncated apex at the humerus, its
base at the side of the thorax, and its sides
formed by the folds of the axilla, that is, the
great pectoral in front, the teres major and
latissimus behind. It is concave, the concavity
looking downwards and outwards. The skin
is fine, covered with hair at its upper part from
the time of puberty, and secreting, by numerous
follicles, a fluid of a peculiar odour,

By raising the elbow higher than the head we
convert the concave into a convex, the folds of
the axilla are removed, the skin made tense,
and the head of the humerus by descending is
made to touch the floor of this region. Press-
ing the arm close to the side lowers the
floor, shortens the margins, and relaxes all the
parts composing the axilla. When the elbow
is drawn a few inches from the side, the
axillary artery and nerves may be felt along
the humerus, and the head of this bone may —
be distinguished. In searching for disease in
the axilla the arm must be placed in all these
positions, but we are most likely to detect any
abnormal condition of the parts when the elbow —
is drawn a few inches from the side, and sup-
ported without any effort of the patient.

>

AXILLA.

Immediately under the skin we find some
cellular substance, containing a small quantit
of fat; and next a fascia of considerable thick-
ness, which gradually loses itself on the side of
the thorax, in the general superficial fascia of
the trunk. It will be found extremely variable
in different subjects, according to the embon-
point of the individual, sometimes loaded with
fat, at other times thin, firm, and somewhat
aponeurotic, with its principal bands stretched
across from the anterior to the posterior wall of
the axilla. In raising it, layer after layer may
be removed, until it opens up into that ex-
tremely lax cellular tissue which attaches itself
to the walls of the axilla, loosely supporting
glands, vessels, and nerves, and permitting all
the motions of which this part is capable. It is
obviously cellular membrane. When enlarged
glands, or abscesses, or tumours of any kind,
form under it, it readily yields, and stretches
before the distending force, never exerting any
painful pressure on them. The cellular tissue
under it is very loose. Numerous vessels ra-
mify through it which are chiefly derived from
the thoracica alaris artery. These vessels are
occasionally ruptured, when extensive ecchy-
moses ensue. Matter formed here passes
easily from one part to another, and gives rise
to obstinate sinuses, not easily remedied on
account of their length and tortuous course.

On carefully removing the dense cellular
membrane of the floor, and that more loose
tissue which it conceals, the edges of the
axillary folds will be seen. Close to the an-
terior of them we observe the thoracica longior
artery, with its accompanying veins and several
lymphatic glands, and, under cover of the
posterior, the subscapular vessels and nerves ;
whilst a great bundle of arteries, veins, and
nerves, with the biceps and coraco-brachialis
muscles, stretch along the humerus. To this
view of the parts the operating surgeon will
look with peculiar interest. It is from below
that we generally operate on the axilla, and the
three sets of vessels just now mentioned con-
Stitute the most important subjects for consi-
deration when the scalpel is to be used. It is
obvious that free incisions may be practised in
the centre of this space or upon its thoracic
side, but that all its other boundaries are beset
with dangers.

_ To follow up the anatomy of this region with
advantage, each of its walls must be examined
in detail. The anterior wall consists of the
pectoralis major and minor muscles. The
pectoralis major is a large flat muscle, of a tri-
angular shape, extending over the front of the
thorax, from the clavicle and sternum to the
humerus. ;

The origin of this muscle is curved, its con-
vexity being directed upwards and inwards; this
may be called its base. ‘The insertion or apex
is outwards and downwards. One surface
looks outwards and forwards, the other back-
wards and inwards. The inferior margin extends
from the seventh rib to the humerusand is nearly
horizontal, folded on itself and free. The outer
edge is nearly vertical, at first about an inch dis-

359

tant from the deltoid, but soon coming into con-
tact with it, and so continuing to its msertion.

The triangular space between the deltoid
and pectoral may be seen even in the living
person when the shoulders are shrugged up,
especially if the individual be thin. It is in this
situation that the axillary artery commences, and
might be cut down upon without dividing any
muscular fibres except those of the platysma ;
it is however protected by the costocoracoid
ligament, and by the edge of the pectoral mus-
cle. In this interval we see the cephalic vein
and a small artery, the thoracica humeraria,
which is the descending branch of the thoracica
acromialis. The cephalic vein is derived from
a plexus on the outer and back part of the
hand. After various communications in its
superficial course it gets between the deltoid
and pectoral muscles, and on arriving at the
triangular interval above mentioned, it dips in
under the edge of the great pectoral and just
above the lesser, to empty itself into the axillary
vein.

When the pectoralis major has been raised,
we bring into view a stratum of cellular tissue,
in which several branches of the thoracica
suprema artery and some nervous filaments
ramify before they enter the muscles. Under-
neath this tissue lies the pectoralis minor, still
concealing the cavity of the axilla.

The posterior surface of the great pectoral is
not nearly so extensive as the anterior ; its fibres
arise from the cartilages of the ribs, and, there-
fore, the extreme limit of the axilla in front is not
to be estimated by the superficial dimensions of
the muscle. A line drawn oblique’ y downwards
and outwards, beginning one inch outside the
sterno-clavicular articulation, and ending an inch
outside the nipple, will nearly mark the junction
of the anterior and internal walls.

This muscle is sometimes torn across by ex-
ternal violence. We have seen this occasioned
by the passage of a railway carriage over it,
and marked by a deep depression, but without
any laceration of the integuments.

The pectoralis minor is shaped like the major,
but it is considerably smaller. Its base is ap-
plied to the ribs, its apex to the coracoid pro-
cess of the scapula. One surface is, turned
outwards and forwards to the greater pectoral,
the other back to the axilla. Attached on the
one hand to the upper edge and the external
surface of the third, fourth, and fifth, and some-
times the second, true ribs, near their cartilages,
by-so many distinct slips, (hence its occasional
name serratus minor anticus,) and an aponeu-
rosis which covers the intercostal muscles, it
terminates in a flat tendon which is inserted into
the inner border of the coracoid process near its
apex. In this situation it is intimately con-
nected with the coraco-brachialis and short head
of the biceps, sometimes sending fibres to be
continuous with the triangular or coraco-acromial
ligament, and in some rare instances the entire
tendon runs across the coracoid process, and
through this ligament to join the capsular liga-

ment of the shoulder-joint. The tendon is
about an inch broad ; very short on the posterior

360

surface, longer on the anterior, and longer still
at the lower edge. The surface now exposed
was covered by cellular tissue, and concealed
by the pectoralis major every where except a
small part of its lowest digitation, which is
generally to be seen below it, in contact with
the integuments.

The upper edge of this muscle is nearly hori-
zontal, and placed about an inch below the
clavicle. In the space between, when some
fat is carefully removed, and some absorbent
glands, we see the axillary artery running down-
wards and outwards, internal and anterior to
which is the axillary vein, and behind it the
nerves. The cephalic vein is observed passing
upwards and inwards from the edge of the del-
toid muscle to the axillary vein, and the tho-
racica suprema artery standing forwards from
the axillary artery and resting on this edge of
the pectoral. The thoracica acromialis artery
runs in this space out towards the acromion
process, and is often a branch of the suprema,
Here, too, we see the lower surface of the sub-
clavius muscle, turned forwards, and covered
by a pretty strong fascia which terminates in
the costo-coracoid ligament.

The costo-coracoid ligament is very thin, but
strong. It extends from the cartilage of the
first rib, just below the origin of the subclavius
muscle, to the coracoid process of the scapula,
in an arch across the vessels and nerves. It is
concave inferiorly, and appears to be only the
thickened edge of the fascia which covers the
subclavius and descends a little below that
muscle. This view of its true mode of forma-
tion is favoured by the fact that it has an at-
tachment also to the clavicle, and consequently
may be called costo-cleido-coracoid. The name
ligamentum bicorne is sometimes applied to in-
dicate its horn-shaped extremities; Blandin
denominates it fascia clavicularis, and Gerdy,
ligament suspenseur de Vaisselle.. As a ligament
it has little power, but as an aponeurosis it pro-
tects the vessels, and sends down a thin process
upon them.

Below the lesser pectoral the vessels and
nerves again come into view, and the thoracica
longior or external mammary artery is seen
passing downwards and forwards along its
loweredge. Fora fuller description ot the pre-
ceding muscles, see THorax, MuscLes oF THE.

The inner wall of the axilla exhibits the ribs,
intercostal muscles, and serratus magnus, with
some vessels and nerves. One of these last is
remarkable for its length and vertical direction ;
it lies on the serratus magnus, and appears as
if flattened against the side of the thorax. It
arises generally by two branches from the back
of the anterior division of the fifth and sixth
cervical nerves (counting eight in the neck). It
communicates with the phrenic, descends be-
hind the brachia! plexus, under the clavicle and
trapezius, appears upon the serratus magnus,
on which it runs a great distance and enters its
lowest division by many filaments. It is classed
among therespiratory nerves by Sir Charles Bell,
by whom it has been named the inferior ex-
ternal respiratory nerve of the trunk, its function

AXILLA. .

being, according to his views, to associate the
muscle to which it is distributed with the ge-
neral respiratory movements. It was known to
antecedent anatomists as the posterior thoracic
branch of the brachial plexus.* ;

Crossing the axilla from the thorax to the
arm, we see two nerves, frequently called nerves
of Wrisberg, ‘They are the external branches,
or costo-humeral, of the second and third inter-
costal nerves. They pierce the external layer
of intercostal muscles opposite the origin of the
serratus magnus, between the second and third
and the third and fourth ribs, and pass out ob-
liquely to the arm, where they are lost in the in-
teguments on the inner and back part of the arm
and elbow, The superior of them is the larger.

The great vessels and nerves are seen pass-
ing from the first rib. to the lower border of the
teres major muscle, forming an arch whose con-
cavity is downwards. By raising the arm to
the horizontal position we obliterate the arch,
and by supinating the hand strongly we bring
them more into view. In the upper third of
this curve the order of the parts, proceeding
outwards, is, the axillary vein, axillary artery,
and plexus of nerves. In the middle the vein
is situated as before, and then the nerves sur-
rounding and hiding the artery; and in the
inferior third we first meet the vein, then the
nerves, and lastly the artery.

The axillary vein is about three inches in
length, commencing a little above the edge of
the teres major; thence it runs upwards, in-
wards, and forwards to the second rib, which
it touches, as also some fibres of the serratus
magnus there arising ; next it gets on the first
intercostal muscles, after which it becomes the
subclavian vein, crosses over the first rib, under
the clavicle, before the scalenus anticus muscle,
and then enters the thorax. It is formed by
the confluence of three veins, viz. the basilic
and the two vene comites which convey their
fluid from the fore-arm, and it is afterwards en-
larged by the accession of those veins which
accompany, usually in pairs, the subscapular,
the thoracie, and the circumflex arteries. It
also receives the cephalic a little higher up, as
before described.

The avillary artery traverses this region
from above downwards in a course doubly ob-
lique, from within outwards, and from before
backwards ; at its upper part it rests on the
chest separated by the serratus magnus muscle,
and lies close under the anterior wall of the
axilla, whilst below it rests on the subscapularis
muscle (posterior wall), and is very near the
arm. Its complicated relations with the nerves,
veins, glands, &c. come more properly under
consideration in the next article (AxILLARY
ARTERY), to which we refer.

* One or two cases of paralysis of the serratus
magnus muscle from injury to this nerve have been

recorded. Velpeau mentions one, which resulted
from a blow inflicted on the inner wall of the axilla:

a permanent projection of the posterior edge of
the scapula backwards, and inability to bring that
bone into close apposition with the thorax, were the
signs on which he founded his diagnosis. Ree Cy-
clop. of Pract. Med. art. PARALYLSIS.)—Ep.

— SS 2

AXILLA.

It is plain from this view of the parts that a
wound in the axilla, near the clavicle, might
penetrate both the artery and vein, and be fol-
lowed by aneurismal varix, but that no such
consequence could follow a puncture of these
vessels lower down. We see too that there
would be much difficulty in compressing the
axillary artery through the anterior wall of the
axilla, (formed as it is of the two pectorals,) ex-
cept in the triangular interval between the
great pectoral and deltoid muscles close to the
clavicle, and that the subclavius muscle and
the ligamentum bicorne would bear off pres-
sure even there to agreat extent. In this place
the vein and artery lie closer to each other than
they do above the clavicle, a circumstance to
be remembered in attempting to command the
circulation of the limb. Collections of pus are
often met with in the cellular tissue under the
great pectoral muscle. In children they will
frequently be found to have been occasioned
by laceration which the tissue has suffered in
the act of raising them up by the arm. These
abscesses elevate the muscle considerably, and
do not always point in the lower part of the
axilla‘'as might be expected. They approach
the surface directly in front in some cases. But
if an early opening were not made, it is pro-
bable they would oftener extend themselves all
through the axilla.

The nerves in the axilla are large, numerous,

and complicated. The principal ones are ina
bundle, at first behind the axillary artery and
then surrounding it. They arise in the cervical
region, interlace in a remarkable way to form
the axillary or brachial plexus, give off some
branches in the neck, abe on reaching the axilla
separate to supply the arm, forearm, and hand.
(For a particular description of this plexus
we refer to the article Cervicat NERVES.)
The nerves we meet with in the axilla, besides
the costo-humeral, are, three thoracic branches,
three subscapular, and six others of much
greater size, viz. the erternal cutaneous, median,
internal cutaneous, ulnar, musculo-spiral, and
circumflex.
_ The thoracic branches are most commonly
three in number ; the anterior, arising from the
seventh cervical, runs in front of the great ves-
sels and is lost in the pectoralis major and
pectoralis minor muscles; the middle, very
small, passes under the vessels and is lost in
the lesser pectoral ; the posterior, the largest,
is the respiratory, and has been already de-
scribed.

The subscapular branches are also three in
number generally; they come from different
points at the upper and back part of the plexus:
the smallest quickly enters the subscapular
muscle: the other two sometimes arise by a
common trunk, or one of them comes from the
circumflex, both run along with the sub-
scapular artery, the larger pierces the teres
major and is lost in the latissimus dorsi, the
smaller is distributed to the subscapularis, teres
major and teres minor.

The external cutaneous, or perforans Casserii,
comes from the external part of the plexus,

361

chiefly from the fifth and sixth cervical branches,
and leaves the axilla by running downwards and
outwards. It is superficial and external to the
axillary artery.

The median arises from the front of the
plexus by two roots, one of which is placed on
each side of the artery; they soon unite, the
nerve then lies on the artery, and inclining a
little outwards escapes from the axilla, being
destined principally for the hand.

The internal cutaneous issues from the inter-
nal and inferior part of the plexus, lies very su-
perficially along the inner side of the artery,
and quits the axilla where the basilic vein is
entering.

The ulnar, arising from the internal and pos-
terior part of the plexus, inclines backwards,
separating itself slowly from the inner side of
the artery.

The musculo-spiral arises still farther back,
and is concealed from view by the other
nerves.

The circumflex nerve arises above and be-
hind all the others, and completely concealed
by them ; it descends before the subscapular
muscle for a little, then turns backwards and
outwards, close to the capsular lizament of the
shoulder-joint, and in company with the pos-
terior circumflex artery ; then it appears on the
outside of the neck of the humerus, between
the long head of the triceps, the bone, and the
teres major and minor muscles, and soon enters
the deltoid in two branches. The situation of
this nerve accounts for the paralysis of the del-
toid muscle which sometimes follows dislo-
cation of the head of the humerus into the
axilla.

Lymphatic glands are found in great num-
bers in the axilla; some are scattered over
the internal wall, but there the majority of them
will be found in a chain along with the external
mammary, or thoracica longior artery. On the
posterior wall they form a chain also, in the
course of the subscapular vessels. Some will
be seen above the lesser pectoral, and several
along the axillary vein. Round this last vein
we see numerous lymphatic vessels twining.

When the clavicle has been detached from
its connexion with the trunk, and along with
the scapula raised from the side, the serratus
mugnus may be seen to form the greater part of
the internal wall, but extending far below it.
This is a flat irregularly quadrilateral muscle ;
one surface of it is in contact with the side of the
thorax ; the other, looking externally, touches
the subscapular muscle, the axillary vessels and
nerves, the two pectorals, the latissimus dorsi,
and the integuments. The anterior edge pre-
sents a convexity forwards, and consists of digi-
tations or fleshy slips which arise from the first
eight or nine ribs. The fibres all run back to
the posterior margin of the scapula, along the
whole of which they are indented

The thoracic surface of the muscle, which
may be seen by cutting through the trapezius
and rhomboid muscles, and pulling out the
base of the scapula from the ribs, rests on
loose cellular tissue, which connects it with

362 * AXILLA.

the ribs, intercostal muscles, and serratus pos-
ticus superior.

_ The posterior wall of the axilla is formed by
the subscapular muscle, the teres major and
the latissimus dorsi, to which the long head of
the triceps may be added. Along the inferior
margin of the subscapular muscle, the subsca-
pulararteryruns. This is a vessel of considerable
size, and deserves the attention of the surgeon.
Itarises from the axillary artery at the tendon of

the subscapular muscle, and passes all along

the inferior or anterior edge of this muscle to
the inferior angle of the scapula, where it ter-
minates by branches which supply the muscles
connected with that point. The teres major is a
long, flat muscle, strap-shaped, one inch and
a half or two inches in breadth, extending from
the inferior angle of the scapula, to the poste-
rior margin of the bicipital groove of the hu-
merus. Its lower edge is in part covered
by the latissimus dorsi and then by the inte-
guments, and forms, principally, the ee
rior fold of the axilla. The posterior surface is
covered by the latissimus, nearer the arm by
the integuments, and then by the long head of
the triceps and the humerus. Its anterior sur-
face corresponds to the subscapular, latissimus,
coraco-brachialis, biceps, and the axillary ves-
sels and nerves.

The latissimus dorsi forms a very small part
of the axilla ; we see it passing over the inferior
angle of the scapula and twisting round the
teres major, so that its posterior surface be-
comes anterior, and the tendon in which it
ends gets internal to that of the teres. Its
edge does not go quite so low as that of the teres
major, but, except there, it prevents that muscle
from touching the axillary vessels. It is some-
times connected to the great pectoral by a fleshy
slip which passes across the axilla.

The axilla has all the conditions which ex-
pose a part to frequent disease; a position
which puts it in the way of many external
injuries; an important joint closely related
to it; bones, liable to fracture ; arteries, veins,
and nerves of great size; numerous lymphatic
glands, connected with the most delicate parts
of the body, lying in it; and then a quantity
of cellular tissue, loose, vascular, and con-
stantly undergoing alterations,

To the observations made on these points
in the course of the present article, we shall
now make a few additions,

Wounds penetrating into the axilla endanger
the nerves, artery, and vein, if inflicted near
the humerus below, or close to the clavicle
above. In the latter situation, as mentioned
before, they may give rise to aneurismal varix.
At the lower margin of the anterior wall the
external mammary artery may be injured, and
along the inferior border of the posterior wall
the subscapular vessels lie exposed.

The shoulder-joint is more liable to disloca-
tion than any other in the body, and in most
cases the head of the humerus comes into the
axilla. The great vessels and nerves are dis-
placed inwards, the circumflex vessels and
nerve often torn. The head of the humerus

lies just below the subscapular muscle, and
forms a tumour in ‘the axilla easily felt from
below. (See SuouLper, ARTICULATIONS OF
THE.

Tie neck of the humerus is often broken
above the insertion of the arm-pit muscles.
The lower fragment is drawn inwards by them
and upwards by the deltoid, whilst the supra-
spinatus directs the upper fragment out. In
this state of things the rough extremity of the
lower piece irritates, perhaps lacerates the ves-
sels and nerves, and if not properly managed
leaves a permanent osseous tumour in the axilla.

Collections of matter are very frequently
met with in the axilla. These occur either
about inflamed glands, or in the cellular tissve
connected with these glands, or they may have
found their way into this region, their focus
being somewhere else. The abundance of cel-
lular membrane here, its vascularity, its in-
cessant movements, and the dragging and
stretching to which it is exposed, render it
very liable to formations of pus. Irritation
of the delicate integuments may occasion them,
and they may be formed in the neck and pass
into this region through the opening at its
apex. The looseness of the texture is such
as to allow suppurations to go on to a great
extent, whilst the movement of the walls pre-
disposes to their termination in sinuses.

The absorbent glands, however, are the or-
gans which most frequently take on disease
in this place. These may become inflamed
and enlarged from sympathy with disease or
injury in any part of the corresponding limb,
the back, the surface of the thorax, or the upper
part of the abdomen. When inflamed, they
often run on to suppuration, or resolution may
follow on the removal of the exciting cause.
Slight lesions of the skin of the parts men-
tioned may determine the formation of ab-
scesses, as a scratch on the finger, a blister on
the chest, &c. Paronychia is not an unusual
exciting cause.

Formidable inflammations of these glands,
often attended with fatal consequences, follow
the absorption of poisons. The cases most
familiar to us in this country arise from wounds
received in dissecting. The glands seem to
arrest the poison in its progress to the circu-
lation. They become excited and congested.
The cellular tissue surrounding, imbedding,
and partly forming them, inflames; a puffy
swelling marks the effusion of serum into the
cellular membrane, which may or may not be
followed by suppuration.

The glands frequently take on the disease
under which the neighbouring mamma labours,
as cancer, fungus hematodes, &e. These
must be removed if the breast be amputated.
They are generally in the course of the external
mammary artery, and no other vessel is in-
terested in their removal, yet the looseness of
the tissue in which they lie renders it unsafe to
cut the little vessels derived from this incon-
siderable artery. Surgeons usually twist or
tear away the glands, or else apply a ligature

to the vessel before they cut it.

Se

EO —— —

:

AXILLARY ARTERY. 363

‘In almost every disease in the axilla the arm
swells on account of the pressure exerted on
the absorbents and veins.

For the BIBLIOGRAPHY see that of ANATOMY

(INTRODUCTION).
(Charles Benson.)

AXILLARY ARTERY (arteria azillaris ).
This artery, which is the continuation of the
subclavian trunk, commences at the outer
border of the first rib, beneath the lower mar-
gin of the subclavius muscle: lying at first on

e external surface of the superior part of the
thorax, it traverses the axillary space, applies
itself to the internal side of the upper extre-
mity, and terminates at the lower edge of the
tendon of the teres major muscle. The ave-
rage length of this vessel is about six inches ;
when the arm hangs by the side it describes a
curve in its course, the concavity of which is
downwards and inwards, but it is brought to a
nearly horizontal right line by raising the arm
to a right angle with the trunk, and it may be
made to describe a curve, the concavity of
which is turned upwards, by raising the arm to
the greatest possible extent of elevation.

The depth of this artery from the surface is

greatest at its commencement, whence to its

se oination it gradually becomes more superfi-
cial.

Relations.—Anteriorly the axillary artery is
covered by the following parts; on first emer-
ging from under the margin of the subclavius
muscle, itis covered by the costo-coracoid li-
gament, beneath which the anterior thoracic
nerves coming from the brachial plexus cross
it in their course to the pectoral muscles, the
vessel then passes under the pectoralis minor
muscle, from the lower edge of which to its
termination the coraco-brachialis lies in front
of it. Posteriorly it rests at its commence-
ment on the first intercostal muscle, then,
with the interposition of a considerable quan-
tity of cellular tissue, on the first digitation
of the serratus magnus, which separates it
from the external surface of the second rib,
it next crosses the tendon of the subsca-
pularis muscle, from the lower edge of which
to its termination it lies on the anterior sur-
face of the tendon of the teres major. Ex-
ternally it is bounded by the lowest cord of
the brachial plexus, until it arrives at the supe-
rior edge of the subscapularis, and for the re-
maining part of its course by the commence-
ment of the external cutaneous nerve. Inter-
nally it is bounded by the axillary vein, which
is in contact with it in the whole of its course,
except while crossing the subscapularis, where
the internal root of the median and the ulnar
nerve separate the vein from the artery.

The lesser press) muscle, in crossing the
axilla at the lower part of the upper third of
that region, divides the axillary artery into three
stages. The first extends from the clavicle to
the upper edge of the lesser pectoral; in this
stage the most important relation which the
artery has, is to the vein, which lies upon its
inner side and upon a plane anterior to it, so
that in a state of distension the vein would

overlap the artery. All the nerves are behind
and external to it. In the second stage, which
is that concealed by the lesser pectoral, the
vein, still on the thoracic side and more an-
terior, is separated from the artery by the
nerves, which, forming the axillary plexus, are so
closely applied to it, behind and on each side,
as to form, as Velpeau remarks, a complete
nervous sheath. In the third stage, which is
below the lesser pectoral and in immediate
connexion with the subscapularis muscle, the
artery is still in the midst of nerves, having on
each side a root of the median, together with
the external cutaneous nerve on the outside
and the internal cutaneous and. ulnar on the
inside, the circumflex and musculo-spiral being
posterior to it. In this stage the vein is in-
ternal and superficial to the artery, but sepa-
rated from it by the nerves which lie on its
internal side.

A ligature cannot be placed on the axillary
artery in any stage of its course without endan-
gering parts of great importance; in the second
stage, however, the connexion of the artery
with the axillary plexus is so intimate as com-
pletely to preclude the possibility of tying it
there without incurring the greatest risk of
serious injury. Hence there are but two situ-
ations in which it can be deemed prudent to
expose this artery. Of these the operation in
the third stage may be accomplished with
greater facility, because the artery is here much
more superficial, and although its relations are
numerous, and in some degree complicated,
they admit of being separated from the artery
to such a distance as will guard them from
injury. To tie the artery in the first stage,
however, is much more difficult, chiefly in
consequence of the great depth at which it
lies, the necessity there is for cutting through
large muscles, and the almost certainty of
troublesome and unavoidable venous hemor-
rhage. The principal part which the surgeon
has to avoid in applying the ligature needle is
the vein.

Branches.—The axillary artery usually gives
off six branches, viz.; 1. the acromial; 2. the
superior thoracic; 3. the inferior or long tho-
racic or external mammary; 4. the subscapu-
lar; 5. the posterior circumflex; 6. the ante-
rior circumflex.

1. The acromial artery (thoracica acromia-
lis) arises from the anterior side of the axillary
artery above the edge of the lesser pectoral
muscle, and after having given off some
branches to the subclavius, serratus magnus,
and first intercostal, it passes obliquely down-
wards and outwards, piercing the expansion of
the costo-coracoid ligament, and arrives at the
posterior surface of the deltoid muscle, where
it divides into a superior and an inferior
branch.

The superior branch mounts by a tortuous
course towards the clavicle; this branch, which
is more particularly designated by the term
acromial, after having given off one or more
branches to the deltoid muscle and the integu-
ments, runs along the anterior border of the
clavicle, behind the origin of the deltoid, until

364 AZYGOS.

it arrives at the acromial end of that bone,
where it is expended in a number of branches
which go to supply the scapulo-clavicular and
scapulo-humeral articulations, and also the
Supra-spinatus and deltoid muscles. This ar-
tery anastomoses with the supra-scapular and
posterior circumflex in the vicinity of the acro-
mion process. The inferior or cephalic branch
descends in company with the cephalic vein in
the cellular interval between the deltoid and
pectoralis major muscles, and is distributed to
these muscles and the integuments.

2. The superior thoracic ( thoracica suprema,
Sem.) is very irregular as to the place of its
origin, coming as frequently from the acromial
as from the trunk of the axillary; it passes ob-
liquely forwards between the greater and lesser
eg muscles, and divides into several

ranches, which are distributed to these two
muscles, the integuments, and more deeply to
the serratus magnus and the two or three supe-
rior intercostal muscles, anastomosing with the
intercostal and internal mammary arteries.

3. Lhe inferior thoracic (thoracica longior
or mammaria externa) is subject to the same
variety of origin as the superior thoracic; it
sometimes arises from the subscapular. This
artery descends on the surface of the serratus
magnus muscle along the inferior border of the
pectoralis major; its .branches are distributed
to the glands and cellular tissue of the axilla,
to the serratus magnus, and pectoralis major
and minor, and the intercostal muscles; it also
supplies the mammary gland and the integu-
ments ; it anastomoses with the intercostal, in-
ternal mammary, superior thoracic, and sub-
scapular arteries.

Scemmerring describes a fourth thoracic ar-
tery, under the name of alaris sive axillaris
glandulosa,* which is distributed principally to
the axillary lympathic glands; this artery is
very irregular in its origin, sometimes coming
from the trunk of the axillary artery, and as
often arising from the thoracica longior or the
subscapularis. Instead of a single artery going
to the glands of the axilla, these parts are more
usually supplied by several small twigs which
arise from the arteries in their vicinity.

4. The subscapular artery is generally the
largest branch of the axillary ; it arises at the
lower edge of the subscapularis muscle, lying
at its origin behind the brachial plexus; it gives
three or four branches to the glands and cellular
tissue of the axilla and to the subscapularis
muscle, after which it divides into two branches,
one inferior, the smaller, the other, larger, called
the external scapular. The inferior branch de-
scends along the inferior border of the subsca-
pularis muscle and the inferior costa of the
scapula between the latissimus dorsi and the
serratus magnus, to which muscles, the
teres major, and the integuments it is finally
distributed, anastomosing with the posterior
scapular artery at the inferior angle of the
scapula. The external branch, circumflerus
scapule of Scmmering, passes backwards
through a triangular space formed by the sub-

* De Hum. Corp. Fab. t. v. p. 189.

scapularis above, the teres major inferiorly, and.
the tendon of the long head of the triceps ex-
ternally, and after having given several branches
to these muscles, it divides into two branches,
a superficial and a deep-seated ; the superficial
branch is distributed to the teres major, teres
minor, infra-spinatus, latissimus dorsi, and the

integuments; the deep-seated branch winds.

round the neck of the scapula under the teres

major, and entering the fossa infra-spinata,

supplies the infra-spimatus muscle, the scapula,
and the scapulo-humeral articulation. This
branch anastomoses freely with the branch of
the supra-scapular, which descends under the
root of the acromion process.

5. The posterior circumflex, next to the sub-
scapular, is the largest branch of the axillary
artery, from the posterior side of which it arises;
frequently it comes from the infra-scapular. It
passes backwards through a quadrilateral space,
bounded in front by the neck of the humerus,
behind by the long head of the triceps, above
by the subscapularis, and below by the teres
major; coursing round the neck of the humerus,
it passes below the inferior edge of the teres
minor, and attaching itself to the under surface
of the deltoid, is principally distributed to that
muscle, giving branches in its course to the
capsular ligament of the shoulder-joint, the
subscapularis, teres major and minor, infra-
spinatus, and triceps; it anastomoses with the
supra-scapularand acromial thoracic by branches
which it sends to the acromion, and with the
anterior circumflex by the branches which it
gives to the articulation of the shoulder.

6. The anterior circumflex is a very small
vessel, arising either from the axillary or the
posterior circumflex; it passes forwards round
the neck of the humerus under the coraco-bra-
chialis and short head of the triceps, to both of
which muscles it gives branches; arriving at the
bicipital groove, it sends off several branches,
some of which descend along that groove, and
others spread over the surface of the head and
neck of the humerus, supplying that part of
the bone and the tendons which are inserted
into its tuberosities; while the continuation of
the vessel entering the bicipital groove ascends
by the side of the tendon of the long head of
the biceps, passes under the capsular ligament,
to which and the other parts entering into the
formation of the shoulder-joint it is ultimately
distributed. This artery anastomoses with the
posterior circumflex and ascending branches of
the superior profunda of the brachial artery.

For the Bibliography see that of ANATOMY
(INTRODUCTION) and of ARTERY.
(J. Hart.)

AZYGOS, (a, Cuyos, jugum.) The term
azygos is applied by anatomical writers to cer-
tain parts of the human body, which, being
situated in or near the mesial line, appear
singly, and not symmetrically or in pairs:
thus we read of the azygos process of the
sphenoid bone, of the azygos uvule muscle,
of the azygos artery, vein, &c. This term,
however, (strictly speaking,) is seldom very
correctly applied, for in the cases of the bony

awa

;
:
;
qi

-AZYGOS.

process and muscle quoted, each is composed
of parts that were originally double or sym-
metrical, which have coalesced in the middle
line so completely as to appear single; as to
the vessel, the description of which will form
the subject of the present article, there is very
frequently an analogous trunk, only somewhat
smaller, on the opposite side of the spine.

Azycos vEIN, Posterior thoracic, Prelum-
bo-thoracique, Vena sine pari, Azygos major.
This vein exists in the posterior part of the
cavity of the thorax, on the right side of the
bodies of the dorsal vertebre; it serves to
receive the blood from most of the intercostal
spaces, from the phrenic, bronchial, and medi-
astinal veins, as also from the vertebre and
vertebral sinuses, and to convey it into the
superior vena cava; it also establishes a com-
munication between this last-named vessel and
the inferior cava through some of its lumbar
branches, and thus connects the veins of the
upper and lower segments of the body, in the
same manner as the internal mammary and
epigastric, and several others of the thoracic
and abdominal arteries inosculate.

In the present article we shall consider not
only the greater and lesser vena azygos, but
also the principal branches which each receives
—namely, the intercostal and bronchial veins.
The right or great vena azygos presents many
varieties as to the size and number of its
branches, as well as in its exact origin; it
usually commences very small opposite the
first or second lumbar vertebra, on the upper
extremity of the right psoas muscle from the
confluence of several minute veins, which com-
municate with branches from the superior
lumbar, capsular, renal, and spermatic veins,
and thus indirectly with the abdominal cava;
it not unfrequently, however, arises by a branch
from the cava itself, in which case it appears
even in this region asa vesse! of considerable
size. Theabdominal portion of the vena azygos
is but short, ascends obliquely inwards, crosses
the right crus of the diaphragm, and enters the
posterior mediastinum between the crura of
this muscle in company with, and to the right
side of the thoracic duct and aorta; it is here
surrounded by so much cellular and adipose
tissue as to be frequently very indistinct; it
sometimes enters the chest along with the right
splanchnic nerve through an opening in the
right crus itself, or external to the latter, between
the attachments of the diaphragm to the body
and transverse process of the first lumbar
vertebra. The thoracic portion of the vena
azygos ascends along the right side of the
vertebral column in front of the right inter-
costal arteries, and covered by the right pleura,
to which it is closely connected, being, in
fact, contained in the subserous cellular
tissue ; the aorta is to its left, and in the in-
tervening adipose matter the thoracic duct is
placed ; the right splanchnic nerve is external
to it or on its right side. Opposite to about
the fourth dorsal vertebra the vein leaves the
Spine, increases very much in size, arches
forwards and to the right, around and above

365
the right pulmonary artery and bronchial tube,
and opens into the back part of the superior
vena cava, immediately above the reflection of
the serous layer of the pericardium on that
vessel, A small fold of the linimg membrane
of the azygos vein, a mere rudiment of a valve,
exists at its junction with the cava; sometimes,
however, this fold is well developed, it is even
observed to be double. Similar folds or valves
are occasionally found lower down in the vena
azygos, but generally it is destitute of valves.

e vena azygos has been seen by Cheselden
to open into the vena cava within the pericar-
dium close to the right auricle; it also occa-
sionally opens into the cava at a point higher
than that which has been stated as its regular
termination, and it now and then joins the right
or even the left vena innominata.

The vena azygos receives several veins; in
the abdomen and in its passage through the
diaphragm it is joined by one or two of the
superior Inmbars, and by small branches from
the diaphragm; in the thorax it receives the
intercostals; the seven or eight inferior inter-
costals of the right side enter it distinctly ; the
corresponding number of the left side some-
times join it ina similar manner, but most com-
monly they first unite into a trunk, called the
left or minor azygos, of which we shall speak
presently. The three or four superior inter-
costal veins of the right side unite into one or
two branches which end in the convexity at the
upper extremity of the azygos major, which
also receives the right bronchial veins in the
same situation, and at a lower point the ceso-
phageal; the latter, like the arteries of the
same name, are irregular in number and in
situation.

The left vena azygos, azygos minor, semi-
azygos, is smaller, but in other respects similar
to the right; it commences by small branches
from the superior left lumbar, capsular, and
renal veins, which unite into a delicate vessel
that sometimes communicates with the right
azygos, and sometimes with the inferior cava ;
it then passes through the aortic opening in
the diaphragm, or through or external to its
left crus in company with the left splanchnic
nerve, and ascends along the anterior and left
side of the dorsal vertebre as high as the
seventh or eighth; it then crosses the spine
behind the aorta, cesophagus, and _ thoracic
duct, to join the right or great vena azygos.
The azygos minor receives the six or seven
inferior left intercostal veins, and as it is
passing across the spine it is generally joined
by a large descending branch which is formed
by the confluence of some of the superior of
these vessels; the azygos minor also receives
the left bronchial veins as well as some branches
from the diaphragm, cesophagus, and medias-
tinum. In some subjects this vein is wanting;
in such cases the left intercostals join the proper
azygos either individually, or by two or three
uniting into a large branch.

The intercostal veins are eleven or twelve in
number on each side; in their course and dis-
tribution they correspond to the intercostal

366

arteries ; they commence each by the union of
small branches near the sternum, which anas-
tomose with the internal mammary veins; they
then accompany the intercostal arteries along
the groove in the lower border of each rib;
near the spine they increase in size, being
joined by several veins from the exterior mus-
cles of the spine, which pass through the
internal part of each intercostal space along
with the posterior branches of the intercostal
arteries ; in this situation also they receive veins
from the vertebral canal, communicating with
the vertebral sinuses on the posterior surface
of the bodies of the vertebra, and passing
through the intervertebral holes along with the
spinal nerves. All the intercostal veins com-
municate with each other over the heads of the
ribs, either by many small or by a few larger
branches; the veins of the opposite sides also
communicate by transverse branches, so as to
give to the anterior surface of the dorsal ver-
tebree, in a successful injection of the venous
system, an appearance somewhat analogous
to the vertebral sinuses on their posterior sur-
face. The first intercostal vein of the right
side generally ascends over the neck of the first
rib, and over the first dorsal ganglion of the
sympathetic nerve, and joins the subclavian
vein or some of its deep cervical branches ;
the second intercostal frequently joins the first,
and sometimes the third also terminates in a
similar manner, but usually the fourth, third,
and often the second open into the arch of the
azygos by one or two branches: these superior
intercostal veins always communicate with each
other and with the azygos below, as well as
with the subclavian above. The remaining
intercostal veins of the right side enter the
azygos separately, or two or three occasionally
unite and end by a common opening; the infe-
rior ascend, the middle take a transverse course,
and the superior descend ; near the spine they
all anastomose freely with each other, so that
the heads of the ribs support a chain or net-
work of these vascular inosculations, as is well
represented in Breschet’s plates of the venous
system. )
The superior intercostal vein of the left side
always joins the left subclavian or some of its
large branches, the internal mammary in parti-
cular; it is usually a large vein, but it presents
great varieties; in some it appears as a third
vena azygos, and might be named the left
superior azygos; in such cases it communicates
below with the inferior azygos about the sixth
dorsal vertebra and above with the left subcla-
vian ; in the intermediate space it receives the
corresponding intercostal veins, also the ceso-
phagzal, mediastinal, and left bronchial; this
vein sometimes also communicates directly
with the right azygos. The remaining left
intercostal veins enter the lesser azygos, or if
this vessel be absent, they cross the spine
behind the csophagus, aorta, and thoracic
duct, and enter the great azygos separately, or
two or three conjoined. The superior and in-
ferior azygos veins of the left side are some-
times continuous, and enter the left subclavian,

AZYGOS.

thus taking a parallel and very similar course
to the vein on the right side, particularly when
the latter opens so high as into either of the
vene innominate. . ,

The bronchial veins arise in the cellular tissue
of the lungs from the extremities of the bron-
chial arteries ; as the branches unite into larger
vessels, these are found to accompany very
closely the divisions of the bronchial tube ;
they leave the root of each lung two or three in
number ; on the right side one joins the arch of
the azygos or the superior vena cava, the others
open into the azygos lower down, or into some
of the mediastinal or intercostal branches.
The left bronchial veins arise in a similar
manner, escape from the root of the left lung,
and open either into some of the superior in-
tercostal veins, or into the superior or inferior
azygos minor. In minute injections of the
lungs these veins are found to inosculate with
the capillary terminations of the pulmonary
arteries. Both the right and left vena azygos
receive numerous branches from the posterior
mediastinum, from the coats of the aorta,
pericardium, esophagus, bronchial glands,
trachea, &c. &c.; these veins pursue no regular
course; they receive names either from the
arteries they accompany, or from the organs
whence they are derived; they require no par-
ticular description.

The vena azygos is the principal vein apper-
taining to the parietes of the chest; it not
only serves to receive the several branches
which have been mentioned, but also maintains
numerous communications between different
portions of the venous system, which must
prove of essential service in case of obstruction
to the circulation in any of the principal
trunks: thus, its abdominal portion communi-
cates either directly with the inferior vena cava,
or indirectly through the medium of the lumbar,
phrenic, renal, or spermatic veins, while its
thoracic end joins the superior cava, and at the
same time anastomoses on either side with
the subclavian vein or some of its branches.
On both sides of the thorax again it inoscu-
lates by its intercostal communications not
only with the internal mammary, but also with
the thoracic branches of the axillary veins, and
along the vertebre it communicates with the
vertebral sinuses, opposite each foramen of
conjunction. This vein, consequently, ap-
gw not only as one of the roots of the cava,

ut also as a loop or second channel between
the two cave, which, in case of the obstruction
of either, more particularly of the inferior, would
convey the blood to the heart, and thus obviate
any impediment to the venous circulation of
the lower segment of the body. Cases have
even occurred in which the inferior cava has
been obstructed or nearly obliterated by the
pressure of a tumour or of a diseased liver,
and in these this anastomosis, and indeed the
whole vena azygos have been found greatly
increased in size. The vena azygos appears
moreover to have been formed as a convenient
means for receiving numerous venous branches
which could not reach any of the large vessels

2 Pee ee ae

BACK.

without some more complicated provision :
thus the inferior intercostal veins could not join
the inferior cava, where the latter is imbedded
in the liver, without perforating the diaphragm ;
neither could the middle and superior inter-
costal, the mediastinal, and the bronchial
veins arrive at the superior cava or at the right
auricle of the heart without a much more
complex disposition of all these parts than
we observe.

For the BIBLIOGRAPHY see that of VENOUS
SYSTEM.
(Robert Harrison. )

BACK, REGION OF THE (surgical
anatomy). Under this denomination, which is
of Saxon origin, it is intended to describe the
posterior regions of the body situated between
the head and the pelvis, including a cervical,
a dorsal, and a lumbar region, varying in breadth
in these different portions, and corresponding
in length to that of the spine. The skeleton
of this extensive region consists of the spinal
column, and a portion of the ribs, and to the
former of these it is chiefly indebted for its
longitudinal curvatures. Thus we find it con-
cave in the cervical and lumbar portions,
convex in the dorsal. (See Sprne.)

In its whole course from the os occipitis to
the base of the sacrum, we observe a central
depression occasioned by the prominence of
muscular masses on each side. In weak and
emaciated subjects a rugged ridge takes the
place of this depression ; the ridge is the series
of spinous processes which have little or no
muscular covering, and are hid when the mus-
cles on each side are much developed. At the
junction of the cervical and dorsal portion,
however, the ridge is scarcely ever obscured,
because there the spines are very long and the
muscles thin; and again, the depression at the
top of the neck is only rendered deeper by
emaciation.

The length of the cervical region is well de-
fined by the external tuberosity of the os occi-

itis above, and by the prominent spine of the

t cervical vertebra below. Its breadth, at the
upper part, extends from one mastoid process
to the other; in the middle it becomes nar-
rower, and inferiorly it again spreads out
almost to the acromio-clavicular articulations.
Its length and breadth vary in different indi-
viduals. In general it is broader, propor-
tionally, in the male than in the female, espe-
cially at the upper part, where, according to
Gall, it may be considered a measure of ama-
tiveness. At the top of this region we see a
remarkable depression, called the suboccipital

fossa, or cervical fossa ; its existence depends
on the absence of a spinous process in the
atlas, while the muscles on either side, chiefly
the complexi, stand out boldly. In fat persons
a quantity of adipose substance fills up this
hollow and nearly obliterates it. The upper
third of the neck, and in some persons much
more, is covered with hair. This part is tech-
nically called nucha, a term of Arabian origin.
Its common appellation is nape of the neck.

(See fig. 2.)

307

The dorsal region corresponds in length to the
twelve dorsal vertebra, with their intervertebral
substances, and in this dimension it is well de-
fined, but its breadth is not so settled ; anato-
mists bound it by the angles of the ribs on
either side, while surgical writers extend it
somewhat farther. This region is convex from
above downwards, and from side to side also,
if we overlook the slight central depression.

The lumbar region extends from the last
dorsal vertebra to the base of the sacrum, and
on each side to the outer margin of the sacro-
lumbalis muscle. These bounderies can gene-
rally be seen and felt without difficulty. Itisa
little concave from above downwards, convex, or
nearly plane, from side to side, with the central
depression slightly marked.

Lnteguments.—The integuments of the back
are every where strong and coarse. They are
particularly so over the spinous processes,
where an imperfectly marked raphe exists ;
they are also more fixed along that line than
elsewhere, on account of the density of the
cellular tissue which connects them to the su-
pra-spinal ligament, and in many subjects the
raphe is hairy.

The sensibility of the skin is much less on the
posterior than on theanterior surface of the body ;
the nerves and vessels are not so numerous, nor
is its organization so high. Hence its resistance
to the action of vesicatories and rubefacients,
which must be stronger, or applied for a
longer period to produce the required effect.
The skin is also very unyielding, so that col-
lections of matter do not readily make their
way to the surface, and if not opened early may
spread under it extensively.

Subcutaneous cellular tissue—On raising the
integuments a layer of cellular substance is
observed, not containing much fat. It is strong,
coarse, and filamentous, and adheres to the
skin more than to the muscles. In passing a
Seton in the neck we pinch it up with the skin,
and transfix it without touching the muscles,
which could not be wounded with impunity.
Along the middle line this fascia is more con-
nected to the deeper parts than it is on either
side, and especially in the dorsal region.

This cellular tissue is frequently the seat of
post-mortem congestions and effusions arising
from the gravitation of the fluids to so depen-
dent a position; hence we generally find it
either very vascular or infiltrated with fluid,
in a state quite resembling anasarca.

A very fine layer of cellular tissue, under-
neath this again, closely adheres to the mus-
cular fibre, and a good deal of motion may take
place between these two layers.

The arteries which supply the skin and fascia
in the neck are branches of the occipital, the
cervicalis profunda, and the transversalis colli,
to which the vertebral and transversalis humeri
may contribute a little. In the dorsal region
the posterior scapular and the dorsal branches
of the intercostals principally supply these
parts; and in the lumbar region we have the

osterior branches~ of the lumbar arteries,
one of these approach the skin in their undi-
vided state, so that superficial wounds here can

368

never be followed by troublesome hemorrhage.
In the fascia we generally find a vein, described
by Godman of Philadelphia under the name
of the dorsal azygos. It arises at the lower
part of the back by irregular roots, runs up
single for some time along the middle line,
and then divides into two branches, one of
which pierces each trapezius, and enters into
the transversalis colli vein. It is small and of
little importance. The other veins are not of
sufficient size to deserve particular notice ;
they are found in company with the arteries.

Nerves.—The nerves of this region are the
posterior branches of all the spinal nerves. The
cervical and brachial plexuses also send some
filaments ; but its nervous supply is, like its
vascular, very scanty.

Lymphatics.—The lymphatics, too, are not
so numerous as elsewhere. We trace them
running to the cervical, axillary, and inguinal
glands, according to their proximity to these.
With the exception of two or three on the cer-
vical portion of the trapezius, lymphatic glands
are not met with here.

The back is peculiarly subject to anthrax in
debilitated constitutions, and in some cases the
tumour acquires great magnitude. It some-
times happens that several anthraxes occur in
succession, until a large portion of the integu-
ments and fascia is destroyed, and the patient
sinks under the disease. Pressure is frequently
the exciting cause. By pressure the vessels are
so obstructed that the vitality of the part is
impaired, and its organization is too low to
enable it to recover from the deadening effects,
especially if the constitution be previously in-
jured. Here too we often meet with furunculi :
they are most common in the nape of the neck.
Fistula in the lumbar region, depending on
diseased kidney, sometimes present themselves.
There is no peculiarity in the cutaneous or
other diseases to which it is liable in common
with other regions.

BACK, MUSCLES OF THE.—The mus-
cles of the back are very numerous and complex.
There is much variety in their origins and inser-
tions in different subjects, and in many cases it is
not easy to decide with which of two adjoining
muscles we are to connect certain bundles of
fibres ; a distinct impression, therefore, is not
always obtained from an examination of the
part, nor will a repetition of the dissection pre-
sent us with the same view in another subject.
Hence it happens that anatomists differ as to
the number of muscles to be met with, some
dividing into two or more muscles what others
consider as one; this proves another source of
difficulty. The names and the enumeration of
them, as given by Albinus, we shall follow
pretty closely: we esteem them the best on
the whole, and they have the advantage of being
generally adopted in these countries: viz. the
trapezius or cucullaris, latissmus dorsi, rhom-
boideus major, rhomboideus minor, levator an-
guli pn serratus posticus superior, serratus
posticus inferior, splenius capitis, splenius colli,
sacro-lumbalis, longissimus dorsi, spinalis dorsi,
semi-spinalis dorsi, cervicalis descendens, trans-

BACK.
versalis colli, trachelo-mastoideus, complerus,

spinalis colli, multifidus spine, inter-spinales,
inter-transversales, rectus capitis posticus major,
rectus capitis posticus minor, obliquus capitis in-
Jerior, and obliquus capitis superior. These
muscles are placed in pairs, one on each side
of the median line; none of them can be said
to be exactly in the middle. We shall examine
them in the order they present themselves to
us in dissecting. .

We find these muscles disposed in layers,
and each layer differing from the others in the
shape or use of the pieces which compose it.
Six such layers may be enumerated. The first
consists of the trapezius and latissimus dorsi,
muscles somewhat triangular in form, and
destined to act principally on the upper extre-
mity. The secund consists of the rhomboidei
and levator anguli scapula. These are qua-
drangular, approaching a square shape, and act
on the scapule. The ¢hird layer is formed of
the serrati, of similar shape, but acting on the
ribs. The fourth consists of the splenii; these,
more elongated than the last, rotate and erect
the head and neck. The fifth layer is com-
posed of very long muscles, acting chiefly as
erectors of the spine and head, viz. the sacro-
lumbalis, longissimus dorsi, spinalis, and semi-
spinalis dorsi, cervicalis descendens, transver-
salis colli, trachelo-mastoideus and complexus.
The sixth layer, again, is formed of short mus-
cles, rotating and erecting the head or minute
portions of the spinal column; these are the
recti and obliqui of the head, the spinalis colli,
inter-spinales, inter-transversales,and multifidus
spine.

First layer—The trapezius and latissimus
dorsi, which form the first layer, almost com-
pletely conceal all the other muscles of this
region, and in superficial extent are scarcely
succeeded by any two muscles in the body.

The trapezius is thin, triangular, and very
extensive. One of its surfaces is turned to the
integuments, and covered by the superficial
fascia, and by a fine layer of cellular tissue
which closely adheres to it. The trapezius
arises from the internal third of the superior
oblique ridge of the os occipitis, from the liga-
mentum nuche, and from the spinous pro-
cesses of the last cervical and of all the dorsal
vertebre. The superior fibres run downwards,
outwards, and a little forwards, the middle
transversely, and the inferior upwards and out-
wards; all converge, and are inserted into the
external third of the posterior border of the
clavicle, the acromio-clavicular ligament, the
acromion process, the upper edge of the spine
of the scapula, and the tubercle which termi-
nates this spine at the base.

The origin of this muscle is by tendinous
fibres which are from half an inch to an inch
long in the occipital portion; in the cervical

they are very short until we come down to the

sixth cervical vertebra, where they begin to
lengthen; at the first dorsal they are an inch
and a half in length, again they diminish, and at
the fourth dorsal spine they are scarcely to be
seen; but at the tenth they again increase in
length, and form a triangular tendon. It some-

Nee fe
- ' Di a

f.

- ferior

BACK.

_ times happens that this muscle has no connexion

with the eleventh and twelfth dorsal vertebre.
The long tendinous fibres of the two trapezii,
at the junction of the cervical and dorsal re-
gions, form an oval aponeurosis of considerable
size, called the cervical aponeurosis, which is
supposed to give greater strength to this part.
All the spinal origin has its fibres blended with
those of the opposite muscle, and supraspinal
ligament. The insertion is by a mixture of
tendinous and fleshy slips, except at the extre-
mity of the spine of the scapula, where a little
tendon is formed which glides over a small
triangular surface to be inserted into the top of
the tubercle. The plane which this muscle
forms is curved on the side of the neck, and its
fibres are there a little twisted. Instead of three
sides this muscle has actually five: 1st, a
superior; 2nd, an internal—these are its ori-
gins; 3rd, an external, which is its insertion,
and two others which are unconnected, viz.
4th, an inferior external, and 5th, a superior
external. Of these the first is so short that it
attracts no notice; the other four are of un-
equal lengths—hence the name trapezius. But
the third and fourth sides are so nearly in one
continuous line that the whole muscle appears
triangular.

The trapezius covers the complexus, the
splenii, the levator anguli scapule, the serratus
posticus superior, the rhomboidei, the supra-
spinatus, a small portion of the infra-spinatus,
the latissimus dorsi, the sacro-lumbalis and
longissimus dorsi. It touches all these mus-
cles, and glides on them by means of a fine
cellular tissue, which contains little or no fat
except over the supra-spinatus. The anterior
superior edge forms the posterior boundary of
the great lateral triangle of the neck, and at its
upper extremity is often connected with the
sterno-mastoid. The two trapezii have some
resemblance to the monk’s cowl hanging over
the neck, hence the name cucullares often given
to them.

By its superior fibres this muscle raises the
clavicle and scapula; by its middle it draws
the scapula towards the vertebral column, and
by its inferior it pulls the tubercle of the spine
of the scapula downwards. If all the fibres act
together, it will cause, the scapula to rotate on
the thorax, so as to elevate the shoulder-joint,
and im this it is powerfully assisted by the in-
portion of the serratus magnus, as in
carrying heavy burthens on the shoulder. It
serves to keep the head from falling forwards,
and will, by its superior fibres, draw the head
to the shoulder and turn the face to the other
side. We use it in shrugging up the shoulders.
It becomes a muscle of inspiration by raising
and fixing the clavicle and scapula, so that the
subclavius, the lesser pectoral, part of the ser-
ratus magnus, &c. may elevate the ribs. The
Spinal accessory nerve (the superior external
respiratory of the trunk) terminates in this
muscle, and, according to Sir Charles Bell,
associates it with the other respiratory muscles.

The ligamentum nuche, from which the chief

of the cervical portion of the muscle arises,

is a line of dense cellular tissue, extending from
VOL. I.

369

the external tuberosity of the os occipitis to the
spine of the seventh cervical vertebra. It’ is
interposed between the two trapezii. A thin
septum extends from it to the spines of all the
cervical vertebrae. In no part does it deserve
the name of ligament in the human subject.
In quadrupeds, however, especially where the
neck is long or the head very heavy, as in the
horse, stag, elephant, &c. it isa powerful elastic
ligament, resembling in structure the ligamenta
subflava of the spine, and is of great impor-
tance by supporting the head without much
muscular effort. In man it is quite rudimental.

The trapezius presents much variety in differ-
ent animals. In the carnivora and rodentia the
clavicular portion joins with the masto-humeral,
(a muscle not found in man,) and is separated
from the scapular portion by the levator anguli
scapule. In the horse the only part of the muscle
developed is that which corresponds to the as-
cending fibres in man, and which are inserted into
the tubercle at the extremity of the spinous pro-
cesses. In the dolphin it is thin, covers all the
scapula, and is inserted into that bone near its
neck. In the mole a fleshy bundle coming
from the loins replaces it. In birds it consists
of two portions, one for the furca, the other for
the scapula. In reptiles there is no trapezius.

Latissimus dorsi.—This muscle is also thin,
triangular, and very extensive, covering the
lumbar region, a part of the dorsal and of the
side of the thorax, and contributing to form the
posterior boundary of the axilla. It is exposed
by raising the integuments, superficial fascia,
and lower angle of the trapezius. Then we
find it arising from the tops of the spinous pro-
cesses of six, (sometimes of four or five, some-
times of seven or eight,) of the inferior dorsal
vertebrae, of all the lumbar vertebre and from
the supraspinal ligament, from the spines and
other eminences of the sacrum, from nearly the
whole posterior half of the crest of the ilium, and
from the three or four lowest false ribs. The
fibres all converge, the uppermost running
transversely, the lowest vertically. It is in-
serted into the posterior edge of the bicipital
groove of the humerus.

The costal origin of this muscle is fleshy, all
the rest is tendinous. The tendinous fibres on
the vertebre are blended with those of the
opposite muscle, and on the sacrum and ilium
with the gluteus maximus. They form a tendon
of great extent, narrow on the sacrum, very
broad on the lumbar region, and again becoming
narrow as weascend tothe dorsal. It is to this
tendinous expansion that the name of lumbar
fascia is given; its fibres are for the most part in
the direction of the fleshy fibres which succeed,
but they are crossed irregularly by some others.
This fascia covers and binds down the lumbar
muscles, giving great strength to the loins; it
is intimately connected with the tendon of the
serratus posticus inferior, the internal oblique
of the abdomen, and the posterior tendon of
the transversalis, all of which are inseparably
connected with its anterior surface. The costal
origin is by fleshy slips which indigitate with
similar slips of the obliquus externus abdominis ;
these are so disposed that the inferior almost

2B

370

conceals the one above it, and so on. The
-muscle on its way to the humerus glides over
the inferior angle of the scapula, from which it
receives a small fasciculus of fleshy fibres; then
it bends under the teres major, forms a tendon
about an inch broad and an inch long, which
is connected at first by cellular tissue, and after-
wards by a bursa mucosa to the front of the
teres major; and is inserted into the inner or
posterior edge of the bicipital groove. Some
fibres of this tendon line the groove, a few pass
up along its edge to the lesser tuberosity. The
axillary vessels and nerves, the biceps and the
coraco-brachialis, are in contact with its tendon.

The upper edge of the latissimus is nearly
horizontal, slightly curved—its concavity up-
wards and free. The anterior edge is nearly
vertical, and for the most part free also. The

posterior or inner edge is connected throughout,”

and takes an extensive irregular sweep. On
- raising the muscle, we shall find that it was in
contact with the serratus posticus inferior, the
sacro-lumbalis and longissimus dorsi, the inter-
nal oblique and transversalis of the abdomen,
the inferior rhomboid, the serratus magnus, the
inferior angle of the scapula, the infra-spinatus
and teres major, also with some of the ribs and
intercostal muscles.

We sometimes meet a fasciculus of muscular
fibres passing from the latissimus dorsi to the
pectoralis major across the axillary vessels and
nerves. In the Edinburgh Medical and Sur-
gical Journal, vol. viii. Dr. Ramsay states
that it is found in one subject out of every
thirty, and may prove inconvenient to the axil-
lary artery, vein, and nerves.

The latissimus dorsi depresses the arm, draws
it backwards and inwards, rotates the humerus
so as to turn the palm of the hand first in-
wards, then backwards. It serves to keep the
lower angle of the scapula in its place. . When
the arm is raised and fixed, it draws the body
up, as in climbing, or elevates the ribs, as in
difficult respiration. In using crutches the
arm is fixed by grasping the handle of the
crutch, then the pectoralis major and latis-
simus pull up the body on the cross-bar to-
wards their insertions; and when the body is
so raised, it is impelled forwards by the action
of this muscle, aided by the feet and by the
body’s own gravity.

In quadrupeds it is a muscle of progression,
pulling the trunk forwards to the fore-leg, which
was previously fixed. The panniculus carno-
sus, which is inserted close to it into the hu-
merus, assists in this action. In birds it is
small, and consists of two portions.

Second layer.—This layer consists of the
rhomboidei and levator anguli scapule. They
are seen on raising the trapezius.

The rhomboidei form a broad thin plane,
separated only by a line of cellular tissue into
the minor and major, extending from the spine
to the scapula, and nearly concealed by the
trapezius.

The rhomboideus minor arises from about
half an.inch of the ligamentum nuche and
' from the spine of the seventh cervical vertebra ;
its fibres run downwards and outwards to be

BACK.

inserted into the base of the map rsync
little above the commencement of the spinous
process of that bone. The rhomboideus major,
three or four times as broad, arises from the
four or five uppermost dorsal spines, runs
downwards and outwards, and is inserted
below the last into the base of the scapula
from its spinous process to its inferior angle.
These two muscles are of the same length,
thickness, and appearance in every respect,
differing only in breadth. Their fibres are
parallel to each other, being tendinous at their
origin, where they are blended with those of
the trapezius, and are inserted between the
serratus magnus and the supra- and infra- —
spinati. The insertion of the major is peculiar;
a tendinous band runs along the base of the
scapula from its spine to its inferior angle, and
it is into this, not into the bone, that the mus-
cular fibres are inserted, nearly at right angles.
This band is attached only at its two extremi-
ties; it is not seen till we cut a few of the
posterior fleshy fibres which do reach the bone.
This arrangement is supposed to allow of
greater freedom of anastomosis between the
scapular vessels. The minor is overlapped at
its insertion by the levator anguli scapule,
in the rest of its extent by the trapezius. The
major is covered by the trapezius principally ;
a very small part of its inferior angle is covered
by the latissimus, and between these it is
separated from the integuments only by the
superficial fascia. The rhomboids get their
name from their shape. Their opposite, but
not their adjacent sides and angles are nearly
equal. Their internal and external edges
are attached; their superior and inferior are
free. The inferior edge of the major is a little
longer than any other. The deeper surface of
these muscles touches the splenii, the serratus
posticus superior, sacro-lumbalis and longis-
simus dorsi, some ribs and intercostal muscles.

These muscles draw the base of the scapula
towards the spine, acting with most effect on
the inferior angle, and thereby depressing the
point of the shoulder. With the trapezius they
draw the shoulders upwards and backwards.

In the simiz the rhomboids extend to the oc-
ciput. In carnivora the levator major scapule
seems to be their occipital portion. In the
horse the levator proprius scapule is the ante-
rior part of the rhomboid, arising from the
ligamentum nuche.

The levator anguli scapule is a long strap-
shaped muscle, situated on the side of the
neck, and extending from the superior cervical
vertebree to the upper angle of the scapula.
Its dragin is by four (sometimes three) ten- —
dinous bundles from the posterior tubercles —
of the transverse processes of the four superior
cervical vertebre ; that which arises from the —
atlas is the largest; they are intimately con- —
nected with the splenius colli behind, and ~
with the scaleni before. The fleshy fibres pro- —
ceeding from them unite, and passing down-—
wards, outwards, and backwards, are inserted
into the inner surface and posterior margin of —
the scapula, from its superior angle to near its —
spine. Here it overlaps a little of the lesser —

B 4 last muscle, but a little broader an

BACK.

rhomboid, and is so united with the serratus
magnus that Dumeril considers it a portion of
this muscle. The dissection of it in some
quadrupeds favours this opinion, but in man
it appears rather in connexion with the rhom-
boid.

This muscle is covered by the sterno-mastoid
at its upper part, then by the integuments, and
afterwards by the trapezius. It rests on the
splenius colli, cervicalis descendens, transver-
salis colli, serratus posticus superior, and lesser
rhomboid.

This muscle pulls the superior angle of the
scapula upwards and forwards, and by rotating
that bone on the thorax becomes a depressor
of the shoulder-joint. The rhomboids act with
it m depressing the joint; but the inferior
portion of the serratus magnus is its direct
antagonist. When the trapezius acts with this
muscle, the scapula is drawn directly upwards.
If the scapula be fixed, this muscle will incline
the neck to its own side.

This muscle undergoes many modifications
in the different families of the mammalia. In
simi it is inserted into the spine of the sca-
pula, not into its angle. In carnivora and
rodentia it separates the two portions of the
mca and is inserted near the acromial
end of the spine of the scapula. In the cat it
arises from the basilar process of the os occi-
pitis and from only one of the cervical vertebre,
the atlas. In the horse it does not exist at all.
In the dolphin it forms a thin tendon which
spreads over the scapula. As to birds and rep-
tiles, it is replaced in them by other muscles.

Vhird layer —Two very thin muscles, the
serratus posticus superior and serratus posticus
inferior, constitute the layer.
| The serratus posticus superior is quadrilateral.
It arises by a thin tendon from the lowest part
of the ligamentum nuche, from the last cervi-
cal and the first two or three dorsal spines.
The fleshy fibres which succeed form a thin
plane, pass downwards and outwards, and are
inserted by four digitations into the superior
border and external surface of the second, third,
fourth, and fifth ribs, a little external to their

gles.
his muscle is covered by the rhomboid,
the eh and, when the shoulder is drawn
back, by the serratus magnus. Its origin is
united to the two former. It covers the splenii,
the longissimus dorsi, transversalis colli, sacro-
Jumbalis and cervicalis descendens; while on
these it is tendinous; then it becomes fleshy
and covers the ribs and intercostal muscles,
Sometimes it has only three points of insertion.

; _ Occasionally we find a bundle of fibres passing
_ from the upper part of this. muscle along the
_ levator anguli scapule to be inserted into the

transverse process of the atlas.
This muscle elevates the ribs and expands

_ the thorax as in inspiration. It binds down
_ the muscles on which it lies, enabling them to
act with more effect.

like the
thinner.
It arises from the last two dorsal and first three

lumbar spines by a thin tendinous expansion,

The serratus posticus inferior is ve

371

which is intimately connected with the tendon
of the latissimus dorsi, and often destroyed in
removing the latter. The fleshy fibres which
succeed pass upwards and outwards to be
inserted by digitations into the four lowest
false ribs. The uppermost digitation is the
largest, and is attached to the rib near its angle ;
the others become smaller as we descend, and
their insertions are more remote from the angles.
The lowest is connected with the cartilage of
the last rib. This muscle covers the longissimus
dorsi and sacro-lumbalis, the ribs and inter-
costals. It also covers the posterior tendon of
the transversalis abdominis, to which it is in-
separably united.

This muscle draws down the ribs as in ex-
piration, and binds down the deep lumbar
muscles.

A thin semitransparent fibrous layer, called
the vertebral aponeurosis, covers the spinal
muscles in the interval between the two ser-
rati. It is continuous with their adjacent edges,
and assists them in binding down the long
muscles of this region. The fibres of which
it is composed pass for the most part trans-
versely, from the spinous processes to the an-
gles of the ribs.

These muscles are generally present in the
inferior animals, when ribs exist, and have no
peculiarity worthy of being noticed here.

The splenii form the fourth layer. They
appear as one muscle, extending from the lower
cervical and upper dorsal spines obliquely
upwards, outwards, and forwards, to the head
and to the transverse processes of the superior
cervical vertebre. Covered below by the
rhomboid and serratus posticus superior, higher
up by the trapezius and levator anguli scapule,
and higher still by the sterno-mastoid, it is
only about the middle of their course that they
become distinct from each other, for they arise
as one.

The splenius colli (or splenius cervicis) is
the inferior portion, not so thick or broad as
the superior, but of greater length. It arises
from the spines of the third, fourth, fifth, and
sixth dorsal vertebrae, and from the interspinal
ligaments, by tendinous fibres which are long,
and form an acute angle below. The flat band
of fleshy substance which proceeds from this
tendon passes upwards, outwards, and for-
wards, then divides into two or three fasciculi,
which are inserted tendinous into the trans-
verse processes of the two or three superior
cervical vertebrae, blended with the attach-
ments of the levator anguli scapule and the
transversalis colli.

The splenius capitis, the superior portion,
arises from the spines of the two superior
dorsal vertebre and of the seventh cervical,
and from the ligamentum nuche as high as the
fourth cervical. At the origin it is tendinous ;
it soon becomes fleshy, passes upwards, out-
wards, avd forwards, to be inserted into the
back part of the mastoid process of the tem-
poral bone, and into the external part of the
depression on the occipital, between the supe-
rior and inferior transverse ridges.

These two portions ought not to be con-

2B 2

372

sidered distinct muscles. They are inseparable
below; their structure, directién, and uses are
alike; and they are inserted similarly—the one
into transverse processes, the other into a part
of the cranium perfectly analogous.

The splenii cover the longissimus dorsi,
the complexus, the transversalis colli, and the
trachelo-mastoideus. The splenii of opposite
sides pass off from each other as they ascend,
leaving a triangular space at the upper part of
the neck, in which the complexi appear.

The action of these muscles is to incline the
head to one side, and rotate it. If the sterno-
mastoideus of the same side act with them, the
head is inclined directly to the shoulder. If
the splenii of opposite sides act together, the
head and ‘neck are kept erect, and in this they
are assisted by the complexus and trapezius.
They strap down the deeper muscles. Their
name is said to be derived from some resem-
blance to the spleen! ( Turton’s Glossary.)

The splenw are generally better marked in
other mammalia than in man. In the mole
they are particularly strong. In carnivora
there is no splenius colli. In the horse the
splenius capitis is inserted into the mastoid
process by a tendon common to it and to the
trachelo-mastoideus. Birds have no splenius.
Reptiles have analogous muscles; but fish
have not.

Fifth layer-——On removing the splenii and
all those previously described, we expose the
Sifth layer of muscles, consisting of the sacro-
lumbalis, longissimus dorsi, spinalis and semi-
spinalis dorsi, cervicalis descendens, trans-
versalis colli, trachelo-mastoideus, and com-
plexus. These, excepting the last, are long
and slender, quite different from those hitherto
described. They are also less distinct from
each other. The first four of them fill up the
vertebral groove from the sacrum to the neck,
and might well be considered as one muscle—
the erector spine.

The sacro-lumbalis, placed most externally,
arises from the posterior surface of the sacrum,
from the margin of the ilium where the latter
overlaps the former, from the sacro-iliac liga-
ments, and from the extremities of the trans-
verse processes of the lumbar vertebre; pas-
sing upwards, and tapering in form, it is in-
serted by tendinous slips into the angles of all
the ribs. It is reinforced in its ascent by acces-
sory fibres (musculi accessorii_), which arise at
the upper margins of the five or six lowest true
ribs, internal to their angles, run upwards and
outwards over one or two intercostal spaces
under cover of the longer fibres, and are in-
serted with them into the angles of the ribs.
These accessory fibres constitute almost the
entire of the muscle at its upper part.

The longissimus dorsi, placed along its inner
side, arises from the spinous and transverse
processes of the lumbar vertebre, and from the
spines of the sacrum and its posterior surface
down to its apex. It forms a thick, somewhat
square, mass in the loins; on the dorsum it
becomes flat and tapering, and ends in a point
at the top of the thorax. It is inserted by two
rows of tendinous and fleshy slips—one row

BACK.

into the transverse processes of all the dorsal
vertebrae, the other row, externally, into the
lower edge of the ribs near their articulations
with those processes. The costal slips are
seldom inserted into all the ribs, the first two
or three and the last two or three being often
without them.

The posterior surface of these two muscles
consists below of a strong tendinous layer, from
which a great part of their fleshy fibres arises ;
it is common to the two as far as the middle
of the lumbar region; there it terminates on
the sacro-lumbalis, but ascends much higher on
the longissimus dorsi, separating into several
distinct bands, between which vessels and
nerves come out.

This tendon is not to be confounded with
the fascia lumborum, which is much thinner
and adheres to its posterior surface.

The spinalis dorsi* lies close along the spi-
nous ridge, arising from the two superior lum-
bar, and three inferior dorsal spines. It forms
a thin muscle and is inserted into the nine
superior dorsal spines. Below it is in contact
with the longissimus; above it is separated
from it by the next muscle.

The semi-spinalis dorsi arises from the trans-
verse processes of the dorsal vertebra from the
eleventh to the sixth inclusive by so many
distinct tendinous fasciculi which pass up, be-
come fleshy, unite and are inserted into the
spines of the four or five superior dorsal and
two inferior cervical vertebre. The name of
this muscle is intended to denote its attachment
to the transverse as well as to the spinous pro-
cesses. It is at first concealed by the longis-
simus dorsi, then lies along the inner side of
that muscle and the outer side of the spinalis
dorsi, with which last it is often united in
description.

These four muscles elevate the spine, and
give it an inclination to their own side.
The sacro-lumbalis will also depress the ribs
slightly.

The cervicalis descendens looks like a con-
tinuation of the sacrolumbalis, between which
and the longissimus dorsi it arises. Its origin
is by tendinous slips from the angles of the
second, third, fourth, fifth, and sixth ribs.
These are at first blended with those of the
sacro-lumbalis ; then they unite and form a
slender muscle, which runs upwards, out-
wards, and forwards, to be inserted into the
transverse processes of the third, fourth, fifth,
and sixth cervical vertebre, between the trans-
versalis colli and the levator anguli scapulz.

This muscle may elevate the ribs or extend
the neck, turning it to one side. It is often
considered as a portion of the sacro-lumbalis, —
and sometimes called musculus accessorius, —
or cervicalis ascendens. The name cervicalis —
descendens, that by which it is best known, was
given to it by Diemerbroéck, who described

*

* Under the denominations transversaire
which may be latinized transversus spine, Bichat
and some other continental anatomists include the
spinalis dorsi i-spinalis dorsi, spinalis colli, and
multifidus spine.— D. ; . 3

BACK.

it as descending from the neck to act on the ribs
and elevate them.

The transversalis colli appears like a con-
tinuation of the longissimus dorsi, and as such
is often described. It arises along its internal
side by tendinous and fleshy slips from the
transverse processes of the second, third,
fourth, fifth, and sixth dorsal vertebrae. These
unite, form a flat fleshy belly, which passes
upwards, outwards, and forwards, to be in-
serted by similar slips into the transverse pro-
cesses of the cervical vertebre from the sixth
to the second inclusive, between the cervicalis
descendens and the complexus. The origin
and insertion of this muscle are connected only
to transverse processes—hence the name.

This muscle elevates the neck and inclines
it to one side.

The trachelo-mastoideus lies to the inner side
of the transversalis colli, by which it is in
great measure concealed. It arises by ten-
dinous slips from the transverse processes of
two or three superior dorsal, and of three or
four cervical vertebre. The slender muscle
enlarges as it ascends, passes a little outwards,
and is inserted into: the posterior border of the
mastoid process, underneath the splenius ca-
pitis. Its inner side rests on the complexus,
then it covers the obliquus capitis inferior and
Superior, and the origin of the digastric, also
the occipital artery. It is by some called the
complexus minor, from the resemblance it
bears to the complexus in its structure. Some
anatomists consider it as the cranial portion of
the longissimus dorsi and transversalis colli.
The origin of its name is obvious.

When in action, this muscle extends the
neck, drawing the head back and to its own
‘side.

The complexus is thicker and broader than
the muscles we have been now describing in
the cervical region. It arises from the trans-
verse and articulating processes of the four or
five superior dorsal vertebre, and from the
transverse processes of the four inferior cervical,
by tendinous slips: these are followed by
fleshy and tendinous bundles. The muscle
thus formed passes upwards and inwards, to be
inserted into the os occipitis between its supe-
rior and inferior oblique ridges. The complexi
are close to each other above, separated only
by cellular tissue which is connected with the
ligamentum nuche; lower down, however,
there is some space between them. This mus-
cle is covered by the trapezius above, by the
splenii in the middle, and by the trachelo-
mastoideus and longissimus dorsi at its lowest
part. It rests on the spinalis colli, the obliqui
and recti capitis. The name is derived from
the complicated intermixture of tendinous and
fleshy fibres of which it is composed. A su-
perficial portion of it is described by Albinus
as the biventer cervicis, but it does not usually
admit of subdivision.

This muscle draws the head back on the
spinal column.

In the muscles of this layer there are no
very striking differences to be observed in the

373

other mammalia, nor in birds. Reptiles and
fishes differ too widely to allow of a com-
parison.

Sixth layer.—On raising the complexus and
trachelo-mastoideus we observe a_ beautiful
series of muscles for moving the head, viz.
the inferior oblique, the superior oblique, the
rectus capitis posticus major and minor. These,
with the spinalis colli, form a stxth layer.

The spinalis, or rather semi-spinalis colli,
arises by four or five fasciculi from the trans-
verse processes of as many superior dorsal
vertebre ; these unite, pass upwards and in-
wards, to be inserted into the second, third,
fourth, and fifth cervical spines, forming a
thicker muscle than the spinalis or semi-spinalis
dorsi.

This muscle commences between the longis-
simus and semi-spinalis dorsi, then it lies be-
tween this last and the complexus. It is
almost concealed by the complexus. It ex-
tends the cervical vertebre and inclines them
to its own side.

The obliquus capitis inferior arises from the
spine of the second vertebra, passes outwards
and a little upwards and forwards, to be in-
serted into the transverse process of the first.
Its origin is connected with that of the rectus
posticus major, and the insertion of the spi-
nalis colli. Its insertion is blended with the
origin of the obliquus superior. It is fusi-
form in shape, the largest of the four muscles
to be met with here, and is often called obli-
guus major. It covers the vertebral artery and
the lamina of the second vertebra, and is itself
covered by the complexus and trachelo-mas-
toideus, and by the posterior branch of the first
cervical nerve.

It rotates the first vertebra on the second,
thus turning the face to its own side.

The obliquus capitis superior (or minor) has
a pointed origin from the transverse process
of the atlas; runs upwards, inwards, and back-
wards, becoming broader, and is inserted into
the os occipitis between its transverse ridges,
just above the insertion of the rectus posticus
major. This muscle is covered by the splenius
capitis, trachelo-mastoideus and complexus.
It covers the vertebral artery and the interval
between the atlas and occiput.

Its action is to extend the head, giving it
some inclination to its own side.

The rectus capitis posticus major is triangu-
lar; its apex arises from the spine of the den-
tata; it passes upwards and a little outwards, to
be inserted by its base into the inferior transverse
ridge of the os occipitis. This muscle and its
fellow arise close together; passing up they
separate. The insertion is overlapped by that
of the superior obhque. The complexus covers
the greater part of it.

This muscle draws back the head, turning
the face a little to its own side.

The two obliqui, with this last muscle, en-
close a triangular space, in which we see the
posterior branch of the sub-occipital nerve
enveloped in adipose tissue, the vertebral
artery, the posterior half ring of the atlas, and

374

the thin ligament which connects this last with
the edge of the foramen magnum. Here we
find the nerve dividing into three branches for
these three muscles.

On removing some cellular tissue from
between the recti majores, we observe the
Rectus posticus minor, shaped like the last,
but much smaller. It arises close to its fellow
from a little tubercle on the back of the atlas,
passes upwards, outwards, and backwards,
to be inserted into the os occipitis between the
inferior oblique ridge and the foramen mag-

num. It is partly concealed by the rectus
major. This muscle can draw the head back-
wards.

In quadrupeds these four muscles are pro-
portionally larger than in man. ‘The inferior
oblique and the rectus major are considerably
larger. Birds have three recti, and only one
oblique—the inferior. Reptiles and_ fishes
may be said to want them, as the analogy is
very remote.

On removing the spinalis colli and all the
museles of the fifth layer, we observe nume-
rous fasciculi of muscular fibres, which are
named inter-spinalis, inter-transversalis, and
multifidus spine. These might be considered
a seventh layer; but they are very analogous
to the small muscles just described, and nearly
on the same plane.

The inter-spinales are short bundles of fleshy
fibres placed between the spinous processes of
contiguous vertebre. ‘They are in pairs in the
neck, where the spine consists of two lamine.
Here also they are well marked. In the dorsal
region they are scarcely visible, and in the
loins they are not easily distinguished from an
interspinal ligament. They are analogous to
the recti postici. ‘They extend the spine.

On the lips of the spinous processes of the
neck some fibres may be shown, to which the
/ name supra-spinal muscles has been given.
They extend farther than from one vertebra to
the next.

The inter-transversales are similar fibres,
scarcely to be demonstrated except in the neck,
where they are in pairs, corresponding to the
divided transverse processes.

The multifidus spine consists of separate
bundles of fibres, extending from each trans-
verse process obliquely upwards and inwards
to the spinous process of the vertebra next above,
or sometimes to the second above. The first
bundle runs from the side or transverse process
of the sacrum to the spine of the last lumbar
vertebra; the last from the transverse process
of the third cervical to the spine of the second.
They are smaller as we ascend, and are not
easily separated from the spinales and semi-
spinales. ‘They support the spine, and rotate
one vertebra on the other slightly.

In the article Spine, the practical utility of a
knowledge of the muscles of this extensive
region will be demonstrated.

For the BIBLIOGRAPHY of this article see that
of ANATOMY (INTRODUCTION).

(Charles Benson.)

BILE.

BILE. Syn. Gall. (Gr. x0%m 53 Lat. bilis 5
Fr. bile ; Ger. die Gulle ; Ital. ele. )—This im-
ator secretiow has been laboriously examined

y several modern chemists of eminence, among
whom we may especially enumerate Thenard,*
Berzelius,+ Soir aa and Gmelin,{ and
Frommherz and Gugert.§ Their results, how-
ever, are so much at variance, that it is impos-
sible to draw any general conclusions from
them respecting the real nature and chemical
components of the bile; these discrepancies
seem partly to arise from the extreme facility
with which chemical agents react upon this
secretion, so that many of the supposed educts
or component parts which have been enume-
rated, are probably products of the different
operations to which it has been submitted, or
at all events modifications of its true proximate
elements: it has been therefore well observed
by Berzelius, that our present chemical know-
ledge of the nature of bile can ouly be consi-
dered as a foundation for the more extended
and satisfactory researches of future experimen-
talists. We shall here endeavour to select
some of the least disputable and most import-
ant facts respecting the chemical properties of
the bile, remarking at the outset to those who
may be inclined to repeat the experiments
which we shall cite, that the indications of re- ;
agents upon different specimens of bile are apt
to vary, and that their action is often much ;
modified by temperature, quantity, and the
mode in which they are used.

Tiere always appears to be mixed with bile .
a variable proportion of mucus, probably deri-
ved from the gall-bladder and its ducts, and
not, therefore, a true component of the secre-
tion: this gives the bile its viseidity, and often
seems in some way to modify its other charac-
ters: in general, however, (ox-gall,) it is a
green liquid, varying much in tint, of a pecu-
liar odour, a bitter and nauseous taste, and a
specific gravity fluctuating between 1.020 and
1.030. It does not coagulate when heated, and
although it may possibly contain albumen, or
something very like it, it is not immediately coa-
gulated by alcohol or by dilute acids. The rela-
tive proportion of solid matter obtained by evapo-
ration is between eight and ten per cent. By
means of acetic acid, the mucus which is mixed
with the bile may to a great extent be separated.
In the mammalia, generally, the bile exhibits
nearly the same characters; and in birds and ~
fishes its components seem to be the same, but
rather more dilute in the former and more con-
centrated in the latter: it is always alcaline, from
the presence of soda, apparently in the same
state of combination as it exists in the serum
of the blood. When bile is evaporated very care-
fully to about half its bulk, and alcohol added,
(in the proportion of about four parts to one of
the evaporated bile,) a coagulated matter is —

thrown down, which has some of the proper- —

* Thenard, Mémoires d’Arcueil, i. aS
+ Lehrbuch der Thierchemie. Dresden, 1831 5 a
and Medico-Chirurgical Transactions, iii. a
{ Uber die Verdauung (Essay on Digestion). =~
§ Schweigger’s Journal, v. 1. , 3

BILE.

ties of albumen; yet neither solution of corro-
Sive sublimate, nor of ferrocyanate of potassa,
which are such delicate tests of that proximate
animal principle in other cases, enables us to
detect it in the original bile. When alcohol is
added to bile which has been evaporated nearly
to dryness, it acquires, when filtered off, a
brownish green colour and bitter taste ; when
evaporated, it leaves a residue which is almost
totally soluble in water; and in this aqueous
solution, dilute sulphuric acid slowly throws
down a grey substance, which appears to be a
compound of the acid and the bitter principle
of the bile; when it has been washed with
water (in which it is not soluble), it dissolves
in alcohol, and if the sulphuric acid be then
separated from it by carbonate of baryta and
filtration, the filtered solution leaves on evapo-
ration a green, transparent, bitter residue,
which appears to be the characteristic princi-
ple of the bile, and which Berzelius calls Gal-
lenstoff. As thus obtained, it is not quite free
from foreign matters, and ether digested upon
it takes up a little fatty matter ; indeed when
bile, concentrated by evaporation, is agitated
with ether, and the latter, after having separated
upon the surface, is poured off and evaporated,
it always leaves traces of a fatty substance,
probably identical with cholesterine. The pu-
tified bitter residue, to which we have just
adverted, is apparently the picromel of Thenard ,
it has a bitter, pungent, and sweetish taste, 1s
inflammable, deliquescent, soluble in water
and alcohol, but insoluble in ether; its solu-
tion is precipitated by many acids, (not by
acetic or phosphoric,) and the precipitate is
nearly insoluble in water, of a greenish colour,
resinous appearance, and fusible at 212°. This
precipitate (consisting of picromel combined
with the acid used to throw it down) dissolves
in alcohol, and is again thrown down by water:
it dissolves in solution of acetate of potash, the
aleali of which combines with the acid of the

_ precipitate, whilst the acetic acid unites to the

picromel to form a soluble acetate. Picromel
dissolves in weak alcaline solutions apparently
without decomposition.

It will be seen from many of the above cha-
racters, that picromel (by which we mean Ber-
zelius’s Gallenstoff) has probably been mistaken
for albumen, and that it is not improbable that
the only true albuminous part of the bile may
be in that equivocal state which is often called
mucus, and which is especially distinguished
by being precipitable by acetic acid. Berze-
lius has suggested an ana!ogy between picromel
and the peculiar saccharine matter which is
contained in liquorice-root; and in many re-
spects their chemical properties are identical.

In the preceding statement, drawn princi-

pally from Berzelius, we have endeavoured to

give the simplest view of the analysis of the
bile; namely, the separation of its muco-albu-
men by acetic acid or alcohol, and of its picromel,
by precipitation with acids and subsequent
decomposition of the precipitate by carbonated
baryte or alcali; its saline contents appear
closely to resemble those of the serum of the
blood ; like which it has an alcaline reaction,

375.

due to soda. We have also selected such ex-
riments, as, with us, have invariably suc-
ceeded: the following results, therefore, of the
analysis of the bile, as given by Berzelius, will
now be intelligible.
Waters isis evi dives les GOAL
Picromel, (Gallenstoff,) inclu-

ding Rtas Soe 8.00
Mucus of the gall-bladde 0.30
Extractive, common salt, and

-lactate of soda .....- at 0.74
Sedan ies Cie dets i eevee. TO AL
Phosphate of sodaand lime and

traces of a substance insolu-

ble‘in alcohol) s05 02.03 2 OOM

100.

The details of the other analyses of the bile
as given by the authorities to which we have
referred above, would be unintelligible if
abridged, and are too voluminous, and too ex-
clusively chemical, to be inserted here; and
moreover, we have generally failed in arriving
at satisfactory conclusions in our endeavours at
a repetition of the various analytical operations
which are described; we must therefore rest
satisfied with giving, in a condensed form, a
general statement of their results. According
to Thenard, human bile contains, water 90.90 ;

ellow bitter resin 3.73; yellow matter gene-
rally diffused through the bile (mucusand colour-
ing matter?) 0.18 to 0.90; albumen 3.82 ; soda,
by which the resin is dissolved, 0.51; phos-
phate, sulphate, and muriate of soda, phosphate
of lime, and oxide of iron, 0.41. Tiedemann
and Gmelin give the following as the compo-
nents of human bile: 1. fat; 2. brown resin ;
3. sweet principle of bile; 4. salivary matter ;
5. mucus; 6. gall-brown (colouring matter?) ;
7. oleic acid, salts, and minute quantities of
other substances. Frommbherz and ‘cugert* have
arrived at yet more complicated results: namely,
1. fat; 2. resin; 3.sweet principle; 4. osma-
zome; 5. salivary matter (Speichelstoff); 6. ca-
seum ; 7. mucus; 8. margaric and other fatty
acids, with phosphate, muriate, and sulphate of
soda and potash; and carbonate, phosphate,
and sulphate of lime. The above, and other
chemists, have published analyses of bile, taken
after death in various diseases, but they present
nothing very important. Tiedemann and Gme-
lin’s elaborate analysis of ox-gall deserves the
perusal of all chemists concerned in such in-
quiries ; it contains, according to L. Gmelin,t
a substance not to be found in any other bile,
and which he has called Laurin or Gallenaspa-
ragin: it may be obtained as follows :—add
muriatic acid to ox-gall and filter; after a few
days a fatty matter appears, which is separated
by filtration; the filtered liquid is evaporated
to a small bulk, when it separates into two
parts, a resinous mass and a sour fluid: the
latter, upon further evaporation, yields more
resinous matter, and at length crystals of com-

* M. Schweigger’s Journal, vol. 1. p. 8.
+ L. Gmelin, Handbuch der Theoretischen Che-
mie, ii. 1012. Frankfurt, 1829.

376

mon salt and taurtn, which are to be separated,
and the latter purified a second by crystalli-
sation. Taurin, when purified, is in prismatic
crystals, neither acid nor alkaline, not altered
by exposure to air, inodorous, of a peculiar
taste: soluble in about fifteen parts of cold wa-
ter, and nearly insoluble in absolute alcohol :
it is fusible, and not decomposed by nitric acid.

In concluding this subject, we must again
express our conviction that many of the sup-
posed proximate components of bile are pro-
ducts of the various operations and re-agents to
which it has been submitted, and that the ana-
lysis of Berzelius, which is the simplest, is
probably the most eorrect: from the uncertain
operation of various precipitants upon bile, and
from the facility with which the results vary,
apparently in consequence of very trifling causes,
there seems to be a peculiar tendency in its
component parts to undergo hitherto unex-
plained modifications.

Bruiary caLcuLi, or gall-stones—These
concretions have been especially examined by
Gren, Thenard, Fourcroy, and as to the fatty
matter which they contain, by Chevreul.*
Human gall-stones are, for the most
part, composed of a crystalline aggregate of a
species of adipocere, or as it has been termed
by Chevreul, cholesterine, (from yon, bile, and
oregeos, solid, ) with more or less colouring
matter, muco-albumen, and inspissated bile ;
they are accordingly of various colours and
textures, but generally brittle and _ friable.
Those which are chiefly cholesterine, or as it
should more properly be termed cholestearine,
are white and crystalline, and lighter than
water; the others are more tough, coloured,
and dense; their specific gravities, therefore,
vary from 0.803 to 1.06. Their chemical ex-
amination may be conducted as follows: they
may be powdered, and digested in water to
separate the inspissated bile: then boiled in
alcohol, and the solution filtered whilst hot ;
as it cools it deposits the cholesterme, and
often retains common fat and its acids in solu-
tion. The portion which resists the action of
alcohol may be digested in a weak solution of
caustic potash, which takes up colouring matter
and muco-albumen: the solution, supersatura-
ted by acetic acid, deposits these, and the co-
louring matter may afterwards be removed by
alcohol. Any common albumen may be de-
tected by ferrocyanate of potash added to the
acetic solution.

Cholesterine separates in white pearly scales
from its hot alcoholic or etherial solution during
cooling; it fuses at about 280°, and when
heated to about 400°, it sublimes: im the open
air it burns like wax. Its ultimate components
are 85 carbon, 12 hydrogen, 3 oxygen. It is
the most carbonaceous of all the varieties of fat.

The gall-stones of the ox frequently consist
chiefly of the yellow colouring matter of the
bile, which is occasionally used by painters on
account of its brightness and durability : it is in-
soluble in water and alcohol, but readily solu-
ble in weak solution of potash, from which it

* Annales de Chimie, xev. 5.

BLADDER, NORMAL ANATOMY.

is thrown down in green flocks by muriatic
acid: nitric acid cautiously dropped into a
solution of this colouring matter gives it various
shades of green, blue, and red.

BIBLIOGRAPHY.—Bianchi, Historia hepatica, 2
vol. 4to. Genev. 1725, Raderer, Experimenta circa
bilis nat. 4to, Argent. 1767. Cadet, Exper. sur
la bile des hommes et des animaux: Mém. de
l’Acad. de Paris, 1767. Bordenave, Analyse de
la bile, ibid, (Savans etrangers, t. vii,) Maclurg,
Experiments upon the human bile, 8vo, Lond.
1772, Goldwitz, Neue Versuche zu ein wahren
Physiologie der Galle, 8vo. Bamb. 1782. Ploucquet,
Exper. circa vim bilis chyliferam, 4to. Tubing.
1792. Thenard, Deux mém. sur la bile: Mém,.
d’Arcueil, t. i. Saunders, A treatise on the struc-
ture, &c. of the liver, 8vo. Lond. 1793. John,
Chemische Tabsllen: Tableaux chimiques, 4to.
Paris, 1816. Chevreul, Note sur la presence de
cholesterine dans la bile de homme: Journ. de
Chim. Med. t. i. and Ann. de Chimie, No. xcv.
Bracconnot, Rech. sur la bile: Ann. de Phys. et
de Chimie, Oct. 1829. Orfila, Elem. de chimie,
2 vol. 8vo. Berzelius, Traité de chimie: Raspail,

Nouv. systéme de chimie organique, 8vo. Paris,

1833; Anglice a Henderson, 8vo. Lond. 1834,
( W. T. Brande. )

BLADDER, (in anatomy.) (Gr. xvotss.
Lat. vesica, vesicula. Fr. vessie, vesicule. Germ.
Blase. Ital. vescica ).—This term is employed

‘to denote a membranous sac, more or less

complicated in its structure, with one or more
orifices, and destined as a reservoir for parti-
cular fluids. We have, for instance, in most
animals provided with a liver, a gall-bladder
or reservoir for the bile; in fishes we havea
swimming-bladder, vesica natatoria; and in
the females of several insects, mollusca and
crustaceans, a bladder, recently described by
Audouin, Milne Edwards, Des Hayes, and
others, the function of which is to receive,
during copulation, the prolific fluid from the
male, and which has, therefore, been called
vesicule copulatrice. In fine, in a great num-
ber of the animals provided witha urinary ap-
paratus we have a urinary bladder, vesica
urinaria. For a particular description of the
first three varieties of bladder we refer to the
articles Liver, Pisces, and Insecra ;—that
of the urinary bladder forms the subject of the
succeeding article.

(R. B. Todd.)

BLADDER OF URINE (normal anato-
my).—(Kvorss ovpodoyos, vesica urinaria.
Germ. Harnblase. Commonly known as the
Bladder.) The urinary, like the biliary appa-
ratus, consists of four principal organs, each
accomplishing a different purpose, yet all con-
tributing to the same end, namely, the sepa-
ration from the circulating medium of a consi-
derable portion of aqueous and saline matter :
these are, first, the kidney or kidneys, which
are the principal, indeed the sole agents in
this function ; secondly, the wreters, the excre-
tory ducts, whose office it is to convey the
fluid secreted, drop by drop, as fast as it is
formed, which is by a slow and gradual pr
cess, to, thirdly, the urinary bladder, which
serves merely as a temporary receptacle for it ;
and, fourthly, the w:ethra, or terminating ex-

7.

a 5

=a

BLADDER, NORMAL ANATOMY. 37T

eretory tube, whereby this fluid is wholly
discharged from the system.

A urinary bladder has not been ascertained
to exist in any of the invertebrate division of
animals, and in the vertebrate there is a great
diversity with respect to it: thus in the class
Pisces, this organ is absent im all the osseous
family, in most of whom, however, the two
ureters unite below, and form a slight heart-
shaped dilatation which opens externally be-
hind the anus in common with the sexual
organs: this vesicle, though somewhat analogous
to, cannot be considered as a perfect reservoir.
In most of the cartilaginous fishes it is absent
also, as in the ray and shark, in whom the
ureters Open as in birds into a cloaca, or reser-
voir common to the renal, sexual, and intes-
tinal discharges; in some, however, of this
family it is present, as in the cyclopterus or
lump-fish, the lophius piscatorius, &c.; in the
latter it is very capacious, and its coats are so
thin as to be transparent; it receives the ureters
anteriorly, and opens, as is usual in fish, behind
the anus, in common with the genital ducts.

In Reptilia, the bladder is present in some,
as the Batrachia and Chelonia ; it is absent in all
the Ophidia, and in many of the Sauria, as
the crocodile, the gecko, and the lizard ; while
again it exists in many of the same division, as
the iguana, chameleon, draco, &c. In the
Batrachia, as the frog and the toad, it is situated
in front of the rectum or cloaca, into which
it opens; the ureters open into the latter poste-
riorly, from whence the urine is directed into
the bladder by the muscular contraction of the
cloaca and of the sphincters of the anus. In
the frog its cavity is large, parietes thin, and
its fundus divided into two cornua. In the
Chelonia, as the tortoise, it is very large, and
the ureters open into the urethra anterior to its
cervix, the urine must therefore return or reas-
cend to enter the bladder. In the Ophidia or
the Serpent tribe, each ureter dilates inferiorly
into a small vesicle, which then opens into the
cloaca, and there is no other approximation to
a bladder; in such of the Sauria as this organ
exists, it opens into the cloaca.

In Aves the bladder is always absent; in
the whole of this extensive class, the ureters
open into the cloaca, and the urine, which is so
earthy as to appear almost solid, is there min-
gled with the feces, in common with which it
is discharged at short and repeated intervals.
In the Ostrich and Cassowary the cloaca is
very dilatable, and its muscular structure is so
organized as to be enabled to retain within it,
and to discharge occasionally a considerable
quantity of urine; hence in these animals a
vesica urinaria has been by some erroneously
supposed to exist.

In all mammalia this organ exists, and in

member of this class the ureters enter it
obliquely at a little distance behind the cervix,
with the exception of the ornithoryncus and
monotrematous animals generally ; in these the
ureters open into the urethra a little beyond or
anterior to the cervix of the bladder, so that
the urine must return or ascend, in order to

enter its cavity; this curious arrangement is

similar to that adopted in the chelonia, and
would appear to indicate, as Carus ingeniously
suggests, that in these strangely formed animals,
in the same manner as in reptiles and in birds,
the allantois (the remains of the urachus of

‘which form the bladder in mammalia) arises

from the expansion of the rectum or the cloaca,
whilst in other quadrupeds it is solely connected
to the genital passages. In all mammalia this
organ presents a tolerably uniform appearance
both as to structure and shape, but great diver-
sity as to capacity or size; the latter appears to
be in an inverse ratio to its muscularity : hence
in Carnivora, the bladder being more muscular,
appears smaller in proportion to the size of the
animal than in some of the Herbivora, where
its coats are thinner, and therefore more dila-
table; in others, however, of the latter order,
in whom it is very muscular, its capacity is
inferior to that of some even of the carnivora :
in the Rodentia it is muscular and small, par-
ticularly if contrasted with the genital appa-
ratus. In quadrupeds the bladder is usually
more covered by the peritoneum, and hence it
appears more loose and free in the abdomen
than in the human subject; its figure is usually
rounded, pyriform, or oval; and it may be re-
marked (and the remark will even apply to the
human child and embryo) that the younger the
animal the more elongated is the bladder, a
fact which is indicative of its derivation from,
or original continuity with the urachus and
allantois.

THE URINARY BLADDER IN MAN is deeply
seated in the anterior inferior part of the pelvis :
it is composed of different tissues, membranous
and muscular, both calculated to yield and
to expand to a slightly distending force, so as
to form a recipient reservoir, while the latter is
fitted by its contractile power to obliterate the
cavity of the organ, and forcibly to eject its
contents. This musculo-membranous viscus
demands the particular attention of the surgical
anatomist, not merely as to its structure, but
as regards its situation and connections, as it
is the seat of many very severe and often fatal
morbid affections, several of which admit of a
perfect cure, and most of considerable relief,
from operation and from various kinds of local
treatment, the safe performance and judicious
application of which greatly depend on a cor-
rect knowledge of the structure and relations
of the organ. We propose first to consider
the form and structure of the bladder in the
normal state, and afterwards to describe its
situation and connections.

Shape.—The figure of the bladder must
vary according to its state of contraction or
distention, in reference to which it is usual
to consider it under three conditions, viz.
the empty or contracted, the full or ordina-
rily distended, and the over-distended. Its
figure in these different states also varies ac-
cording to the sex and age of the individual,
the bladder of the infant differing materially
from that of the adult, and that of the adult
female from that of the male; the bladder of
the embryo also differs from that of the fully
developed fetus. The younger the animal, the

378 BLADDER, NORMAL ANATOMY.

more dyes its form resemble that of inferior
animals, and it is an organ very fully developed
in the young of all animals who possess it.
This organ, in the adult male, when empty or
contracted, is a flattened triangle, the transverse

and yertical axes being considerably greater

than the antero-posterior one; in this con-
dition the bladder is buried deep in the pelvis,
behind and partly below the symphysis pubis;
the base of the triangle is in front of but not
very closely applied to the rectum, unless the
cavity of the latter be fully distended. When
the bladder is expanded in the adult male to
that moderate degree which in perfect health
usually excites a slight feeling or desire to void
the urine, and when the quantity accumulated
may amount to half a pint or upwards, its
figure is then somewhat oval, its vertical axis
being considerably greater than either the
transverse or the antero-posterior, the two latter
being then nearly equal. The larger end of
this ovoid sac rests inferiorly and posteriorly
on the rectum, and is of an irregular form ; the
smaller end, which is more regularly sphe-
roidal, is directed upwards towards the abdo-
men, and somewhat forwards, and occasionall
also a little towards the left side. When the
bladder is over-distended from any cause, it
becomes considerably increased in every dia-
meter ; it first expands in its lower and middle
portions, until the pelvic parietes resist;
it then enlarges superiorly to an indefinite
degree, and at the same time the whole organ
rotates a little forwards by its superior, and a
little backwards by its inferior fundus. Its
figure in this over-distended condition is not
merely enlarged, but it also presents a totally
different, or rather a reversed shape: the larger
extremity of the oval is now superior, occu-
pying the hypogastric region, which it ren-
ders prominent and tense in a degree propor-
tioned to its distension. These observations as
to the form of the bladder will not apply in
every instance, as occasionally this viscus pre-
sents irregularities both in size and shape, as
well as in the density and delicacy of its tunics.
The bladder in the female child does not differ
from that of the male of the same age, but in
the adult of each sex it presents peculiarities.
In the contracted state it is nearly similar in
each, only somewhat flatter in the female.
When distended, in the latter it presents a more
triangular form, the sides somewhat rounded,
than it does in the male, where the ovoid form
prevails; in the female its lower fundus admits
of greater lateral extension in conformity with
the shape of the pelvis, and its transverse axis
is longer in proportion than in the male; hence
it assumes the triangular more than the oval
figure. ‘This character is more remarkable in
the female who has borne children than in the
virgin; in the former the bladder, when dis-
tended, appears to exhibit the effects of the
pressure of the uterus posteriorly, and of the
pubes anteriorly, being flattened in each of
these aspects: in some instances it resembles a
small barrel placed tranversely..

In the foetus and infant of a year old the
bladder in figure more resembles that of a qua-

_at each extremity.

druped ; when distended, it is pyriform, like a
bottle or a flask reversed, the larger end, or the
superior fundus being in the abdomen, and
the smaller extremity tapering into the urethra.
This is the only portion in the pelvis; at this
age its vertical axis greatly exceeds its other
diameters, and even when empty the greater
portion of it is in the abdomen. As the child
Increases in years and size, its pelvis expands,
the bladder gradually descends into this region,
and in the same proportion its lower fundus
enlarges, so that at about six or seven years of
age it presents a more oval form, both extremi-
ties being nearly equal, and very little of it
rising above the pubis, unless when distended.
From this period it continues to acquire gra-
dually the adult figure; that is, its inferior
fundus and body enlarge, while the superior re-
mains stationary ; hence it becomes shorter in its
proportions, and broader below, so as to assume
the triangular shape when empty, and the ovoid
when distended. About two months before birth
the bladder is very much elongated, its upper
extremity being somewhat pointed, and ap-
proaching the umbilicus in the direction of the
urachus. When distended, it presents some-
what the appearance of a cylinder contracted
Soon afier birth the upper
fundus becomes rounder, and then it acquires
the pyriform figure, which in the course of a
few years undergoes the gradual alterations that
have been already noticed.

The capacity of the bladder in the adult
cannot be accurately ascertained, as it varies
from a number of circumstances, such as age
and sex, health and disease: thus irritation
general or local, ischuria renalis, cholera, &c.,
will cause it to contract, while retention of
urine, paralysis, fever, &c., will allow it to
enlarge. Custom or habit will also affect it,
likewise the position of the body, pregnancy,
the nature or peculiar quality of diet, the tem-
perainent of the individual, the temperature of
the atmosphere, the state of society, &c. In
the same individual it will at one time contract
so as to retain only a few drops, and at another
it will dilate so as to centain one, two, and
even three pints. Generally it is more capa-
cious in women, particularly in those who have
borne children, than in men.

In children the bladder, although very dis-
tensible under certain circumstances, is usually
less capacious in proportion than in the adult
or old, probably because it is more muscular
and irritable; and hence, too, the more fre-
quent desire to contract and empty its contents.

When the bladder is moderately distended,
anatomists and pathologists have been in the
custom of dividing it into four regions for the
purpose of more accurate description ; viz., the
superior part or the upper fundus, the middle
part or body, the inferior part or the lower
fundus, and the cervix or neck. This arrange-

ment is not very correct, for it can only apply —

to this organ when distended; the term su-

perior fundus also is obviously objectionable, —

and was probably derived from examining this
viscus in other animals, or in the human fetus
where the lower fundus does not exist; neither

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BLADDER, NORMAL ANATOMY.

can any exact distinction, or even an approxima-
tion to such, be made between these several
compartments. A more accurate knowledge of
this organ may be obtained by examining both
internally and externally its several aspects,
which are six in number, and which may be
regarded as distinct regions; viz., an anterior
and posterior, two lateral, and a superior and
inferior. We shall examine each of these ex-
ternally, and defer any remarks on their in-
ternal aspect until we come to speak of the
lining membrane or the mucous coat of the
bladder.

The anterior region, in consequence of the
obliquity of the pelvis, looks also downwards.
When the bladder is contracted, this region is
behind and in contact (cellular tissue only in-
tervening) with the lower half or three fourths
of the symphysis pubis, and with the pubic and
triangular or interosseous ligaments ; when dis-
tended, it rises above the bone, and is connected
by an abundance of cellular and adipose tissue
to the lower portion of the recti and transversi
muscles ; padine no peritoneum is there inter-
posed, this part can be punctured with safety
during life. At the lower border of this region
is the neck of the bladder, the upper surface of
which is firmly attached to the lower edge of
the symphysis pubis by two horizontally placed
fibrous cords, which are named the anterior
ligaments of the bladder, and which will be
more particularly noticed presently. Between
and beneath these, some veins also run upon
this surface of the bladder. The whole of this
region is deprived of any peritoneal or serous
covering.

The posterior region has an aspect upwards
also; it is smooth and covered throughout with
peritoneum. When the bladder is contracted,
this small region in the male pelvis is in con-
tact with the fore-part of the rectum, or with
such of the floating abdominal viscera as may
chance to intervene; in the female with the
fore-part of the uterus. When this region is
distended, it presents a broad smooth convex
surface, which presses more against the rectum
and supports the convolutions of the small in-
testines.

The lateral regions, when the bladder is
contracted, are little more than margins or
edges, and present nothing worthy of notice;
but when distended, each becomes a broad
surface, somewhat triangular, the base below
and the apex above, the posterior portion, nearly
the half, is covered by peritoneum, the anterior
portion is connected by cellular tissue to the
patietes of the pelvis: the obliterated umbilical
artery ascends along its superior posterior por-
tion, and the vas deferens, which crosses to the
inside of the latter, runs along this region in an
oblique direction downwards and backwards,
and marks the anterior limit of the peritoneum.
From this region the broad lateral fold of this
membrane extends to the iliac fossa, and at its
inferior border is that reflection of the vesical
fascia which is named the true lateral ligament
of the bladder.

The superior region, by some called the
superior fundus, is, when the bladder is empty,

379

little more than a point prolonged into the
urachus; but when distended, it presents its
large and convex surface upwards and forwards ;
to it is attached the superior ligament of the
bladder, which consists of three fibrous cords,
the urachus and the obliterated umbilical arte-
ries ; behind these this region is covered by
peritoneum, but anterior to them it is not.
The former portion is in contact with the con-
volutions of the small intestines, the latter with
the recti muscles.

The inferior region, or the inferior fundus,
or the base of some authors, always exists
as a distinct surface, whether this organ be
contracted or distended, but of course larger in
the latter condition. It is rather more exten-
size in a transverse direction than from before
backwards, and is larger and more distinct in
the male than in the female: its lateral por-
tions in each sex are in contact with the leva-
tores ani muscles, and correspond to the spaces
between the anus and the tuberosities of the
ischium. In the female its middle portion is
in contact with the vagina, in the male with the
rectum in the middle line, and with the vasa
deferentia and vesicule seminales on either side ;
to the latter it is closely connected. ‘The cel-
lular and adipose tissue on and around this
region in the adult is very abundant, and con-
tains numerous veins.» This region is covered
posteriorly by peritoneum, which extends to a
transverse line connecting the centre of each
vesicu!a seminalis. This line corresponds to
the convexity of the cul-de-sac formed by the
reflection of this membrane from the bladder to
the rectum. In front of this line this region
is covered in the middle only by a fascia and
by some cellular tissue as far as the base of the
prostate gland, which extends for some dis-
tance along its anterior portion, and on either
side are the vasa deferentia and the anterior
terminations of the vesicule seminales. When
the bladder is distended in the adult, this surface
is enlarged, not only in superficial extent, but it
also swells backwards and downwards towards
the rectum, and even presses against and into
that intestine, so as in some rare cases to admit
of being felt by the finger introduced per anum.
To this portion the name of ‘bas fond’ is com-
monly applied. In the adult this bas fond, that
is, the posterior part of this region, is the lowest
portion of the bladder, and hence cannot be
evacuated except by the contraction of the
organ or by surrounding pressure. In man, in
advanced life, it is often found dilated into a
sort of pouch, which is behind and quite below
the level of the anterior part of this region, as
well as of the neck of the bladder, forming in
some instances of debility a sort of permanent
reservoir, and one in which calculi are not un-
frequently contained. In the foetus this pouch
or fundus does not at all exist, the cervix or the
urethral opening being then the most depend-
ing part, which circumstance offers another
reason for the power of retention of urine being
less at that age than ata later period of life. Some
writers limit the inferior region to so much of
this aspect of the bladder as is uncovered by
peritoneum, and therefore consider the posterior

380 BLADDER, NORMAL ANATOMY.

part of it as appertaining to the posterior region.
_ Anatomically we consider this incorrect, as the
vesicule seminales are acknowledged by all to
be situated on the inferior region, and the cul-
de-sac of the peritoneum certainly descends
between these bodies to within nearly one-half
or three-fourths of an inch from the prostate
gland. Ina practical point of view it is most
essential to keep this in mind, because in the
operation of recto-vesical paracentesis this mem-
brane is endangered, and would certainly be
perforated if the trochar were passed through
the posterior portion of this region. The sur-
face of the bladder which can be opened from the
rectum in that operation is comparatively small;
it is of a triangular form, nearly equilateral,
situated on the anterior part of this region. The
base is behind marked by the convex border of
the peritoneal cul-de-sac: the apex is at the
notch in the base of the prostate gland, and the
sides are the vasa deferentia and vesicule
seminales. While all these parts are in situ,
this space is but small; when, however, the
bladder has been removed from the subject,
distended, and dissected, this space appears
much more ample, because the peritoneum
recedes from it in proportion as the attach-
ments of the former have been loosened.

The bladder presents to our notice three
diameters, viz. the transverse, antero-posterior,
and the vertical; the latter is also called its
axis. In the contracted state the antero-pos-
terior can scarcely be considered as existing ;
but when distended, this and the transverse
diameters are nearly equal. In all states, at
least in the male, the vertical diameter or axis
is the longest ; this line leads in the adult from
the centre of the upper region to that of the
lower region or fundus : in the foetus and infant
it leads from the urachus to the orifice of the
urethra; if this line be contrasted with the
axis of the trunk or abdomen, and with that
of the pelvis, it will be found to correspond
very nearly with the direction of the latter, and
to pass very obliquely with respect to the
former. The axis of the trunk may be regarded
as nearly a vertical line, descending through the
thorax and abdomen to the pubis, whereas the
axis of the pelvis, or rather of its superior
orifice, will pass obliquely downwards and
backwards, and if produced at either end, it
will pierce the recti muscles between the um-
bilicus and pubis anteriorly, and the lower end
of the sacrum posteriorly. The vertical axis
of the bladder in the adult is on a lower plane,
but nearly parallel to that line ; in the foetus it
is more parallel to that of the trunk, the blad-
der at that age being placed more in the ab-
domen, and in a more vertical direction than
in the adult.

The bladder is composed of several mem-
branous lamine, called coats or tunics: these
are essentially three in number, a serous, a
muscular, and a mucous. They are connected
together by cellular tissue, the lamin of which
being two in number are also considered coats ;
so that the whole number of tunics is stated
by most writers as five. First, the serous or

peritoneal is but a partial coat; it covers those

portions only which come in contact with some
of the abdominal or pelvic viscera, namely, all
the posterior region, and the posterior portions
of the lateral, and of the superior and inferior
regions ; consequently it is deficient on all
the anterior region, and on the anterior part of
the superior, and of the lateral and inferior
regions. The course of the vasa deferentia
marks the extent or the limits of this mem-
brane on the bladder; all that portion which is
behind and between these tubes is covered by
it, except the small triangular area already
noticed on the inferior region; all that which is
anterior to these vessels is uncovered by this
membrane. The peritoneum arrives at this
viscus from the fore-part of the rectum in the
male, and from that of the uterus in the female,
and is continued from its lateral regions to the
iliac fossee, and from its superior fundus to the
inside of the recti muscles. This membrane is
not very closely attached to the subjacent
coat ; it can be easily separated from it; it is
much stronger and more elastic on this organ
than on any of the chylopoietic viscera. When
the bladder is distended, there is more in pro-
portion covered by peritoneum than when it is
contracted. The female bladder has more of the
peritoneum on its upper fundus, and less on its
lower fundus than the male bladder, and in the
foetus and infant it is still more extensively
covered by this membrane, which then extends
over the whole of the upper region and over a
small portion of the anterior. As the peritoneum
passes from the sides of the bladder to the
iliac fosse, it forms folds, improperly called the
lateral ligaments, and in passing from the back
of the bladder to the rectum or uterus, a similar
fold on each side, called the posterior ligaments
of the bladder. Between these the cul-de-sac
of the peritoneum descends; this in the male
subject is the lowest portion of the peritoneal
cavity, it extends to within about three inches
and a half of the anus: in ascites it has been
known to be somewhat lower, and has even
been tapped in this situation from the rectum.

2dly. The external or first cellular coat con-
nects the serous to the muscular tissue; it also
covers those regions of the bladder where the
serous membrane is deficient. In the lateral
regions it is more distinct and thick, and is
particularly abundant anteriorly between it and
the pubes, where it is also very lax, to allow
this organ when distended to move freely as it
rises out of the pelvis into the abdomen. It
contains some but not much adipose matter ;
towards the inferior and lateral parts it con-
tains many bloodvessels, chiefly venous, and a
great number of nerves, which can be distinctly
traced from thence in all directions over the
bladder. Towards the vesicule it is dense and
white, and supports a number of veins; this
coat is strong, resisting, and elastic; it binds
together, supports, and assists the muscular
fibres.

The third coat of the bladder is the muscular :
this is composed of fasciculi running in dif-
ferent directions, and which, though they ap
pale and feeble when contrasted with the volun-
tary muscles, are yet much stronger and redder

,

7
q
3
+

BLADDER, NORMAL ANATOMY.

than those in the corresponding coat in most
of the other hollow viscera, being intermediate
in these respects to those of the stomach and
cesophagus ; this tunic, however, presents great
diversity as to colour and density in different
individuals. In the contracted state of the
bladder, it of course appears more dense than
in the distended ; in the latter, but particularly
in the over-distended state, it appears thin and
imperfect in some places, in consequence of
the fasciculi being separated from each other.
In the young, ceteris paribus, it is stronger
than in the old, and in the female than in the
male ; but long-continued irritation at any age
and in either sex has the effect of thickening it,
as also any disease which causes obstruction to
the flow of urine. If the bladder be removed
from the body, slightly distended and sub-
jected to maceration for a few hours, this tunic
will admit of more distinct examination ; its
fibres will then be seen to take such different
directions as to admit of a tolerably easy,
though not a perfectly natural separation into
distinct laminze, the fibres in the first or super-
ficial of which have a longitudinal course ; be-
neath this is a second stratum, whose fibres
are transverse or circular; and in some situa-
tions even a third lamina can be distinctly
seen, the fibres of which are by some des-
cribed under the name of oblique, but the
term reticular would appear more correct: in
general these three lamine can be made dis-
tinct,. particularly on the anterior part of the
bladder. The first or longitudinal lamina con-
sists of the longest, strongest, and most nu-
merous fasciculi; many of these are connected
superiorly to the urachus, thence they descend

incipally on the fore and back part of the

ladder, a few only along the sides ; inferiorly
they terminate about the neck. These fibres are
very parallel, and much stronger on the an-
terior and posterior aspects than upon the sides,
where they run more obliquely or irregularly,
and decussate with one another. The inferior
attachment of these fibres in the male subject
may be ascertained by careful dissection to be
as follows :—those on the fore part of the bladder
are connected chiefly to the anterior ligaments,
or to. the reflections of the fascia from the pubis
on this organ ; these appear as shining and dis-
tinct as tendons, and have been by some con-
sidered as such to these muscular bands. Above
this insertion these longitudinal fibres appear
very numerous, and those on the right and
left of the median line distinctly decussate or
interlace. Several here also take a transverse or
an arched or semicircular course; some of these
are very distinct and are inserted laterally ;
they must serve to strengthen and to bind
down the longitudinal fasciculi. The latter
in this situation can be divided into layers,
the superficial of which only are inserted,
as has been described, into the anterior
ligaments of the bladder, and through these
into the pubis. The deeper set are inserted,
some into the dense cellular tissue about the
upper surface of the prostate, and some pass
deeper, and intermingle with that circular mus-
eulo-cellular tissue which surrounds the cervix,

381

and which constitutes the true sphincter. Some
of those longitudinal fibres, particularly more
laterally, pass so deep in this situation as to
be very distinctly seen, when the bladder is
opened, through the mucous lining of the orifice
of the urethra. This disposition of the longitu-
dinal fibres we consider as important, as it must
enable them during their contraction to draw
out or expand the sphincter, so as to allow of
the escape of the urine. Laterally these longi-
tudinal fibres are attached, a few of them to
the margin of the prostate, while others expand
over the lateral lobes of this gland, and are in-
serted into the fascia which covers it. Poste-
riorly these fibres are very distinct, particularly
near the inferior surface of the bladder between
the two ureters ; to these last-named tubes seve-
ral of these fibres are connected: some ascend
upon them in arches concave upwards; these
we have traced several inches along the ureters ;.
while others descend in the same course with
them, and are inserted into the trigone of the
bladder. The longitudinal fibres collect into a
strong flat band between and beneath the two
vesicule, over which however no fibres pass
as they do over the prostate, which circum-
stance clearly separates these vesicles from,
while the contrary disposition rather connects
the prostate with, the urinary excretion. This
band of fibres can be followed near to the base
of the prostate; some of its fibres are then in-
serted into the submucous fibrous tissue in this
situation, others into the base of the gland itself;
and very generally one long delicate but distinct
band enters the notch in the base of the gland,
passes beneath the uvula and middle lobe of
the prostate, into which it is sometimes insert-
ed, but it can frequently be traced nearly an
inch further forward to be inserted by a delicate
tendon beneath the seminal caruncle or the
verumontanum, which is partially covered over
by a fold of mucous membrane or by a sort of
prepuce. The effect of this band of the longitu-
dinal fibres must be to depress the uvula, and
thus to open the orifice of the urethra, and also
to depress and to draw the seminal caruncle (a
sort of organized glans) downwards and back-
wards within the prepuce or sinus pocularis,
which covers it, and thus protects it from the
irritation of the urine. In the female the lon-
gitudinal fibres are inserted anteriorly and late-
rally into the cellular, glandular, and vascular
tissue which surrounds the neck of the bladder,
and posteriorly into a more dense tissue which
connects the urethra to the vagina; some fibres
also pass in deep, as in the male, to be attached
to the sphincter. This muscular lamina is de-
scribed by the older authors as a distinct mus-
ele, the ‘ detrusor uring, arising from and
around the urachus by numerous fibres, which
thence descend and expand over the whole
surface, and again concentrate towards the neck
of the bladder to be inserted by one or two
tendons into the ossa pubis. This account,
however, is by no means eigend correct ; for
on attentively examining this muscular lamina,
we frequently find strong transverse fasciculi
crossing superficially to the longitudinal fibres,
most frequently on the anterior region, but also

.382 BLADDER, NORMAL ANATOMY.

near the neck. Occasionally some of the longi-
tudinal fibres alter their direction gradually or
‘\abruptly, as may be particularly noticed about
the ureters and also on the lateral regions.
Great diversity exists as to the arrangement of
this tunic in the lower animals: thus in the
dog this plane consists of strong and regularly
parallel fibres, whereas in the ox they assume a
reticular and irregular course: in man they re-
semble the arrangement of the carnivorous more
than that of the graminivorous animals. This
tunic must have the effect of compressing the
bladder towards the ossa pubis, and of course
urging the contents of the cavity in that direc-
tion, while at the same time some of its fibres
will expand the orifice of the urethra by draw-
ing out the sphincter above and on either side,
and below by depressing the uvula and the
verumontanum. This stratum of muscular
fibres can be raised with a little careful dissec-
tion ; a few fibres must be divided, which now
and then change their direction, and join some
of the deeper orders: this separation is difficult
and can be but imperfectly made on the lateral
regions, but on the anterior and posterior it can
be fully accomplished. The second order of
muscular fibres is circular or transverse; they
are paler, weaker, and more scattered than the
former, particularly towards the superior part
of the bladder, where they are often indistinct.
As they descend they increase in thickness, par-
ticularly near the cervix, where they are so
close and distinct as to have induced many to
consider them as a sphincter to the bladder,—a
term, however, to which they do not appear to
have been entitled, for there is no distinction
between the fibres in this situation and those
which have a parallel course at a greater dis-
tance ; and inasmuch as the latter are obviously
designed to contract the organ and to expel its
contents, it is most probable that the former
must contribute to the same effect, and forcibly
expel the last drops which it contains: indeed
it is impossible to draw such a line of distinc-
tion in this lamina as could denote the limit
between the expelling and the retaining or
sphincter fibres. In addition to this plane of
circular fibres, several others may also be ob-
served taking a parallel direction ; thus we oc-
casionally find transverse bands superficial to
the longitudinal plane, both on the anterior and
posterior regions in different situations. We very
generally also find them near the superior fun-
dus, and constantly on the anterior and lateral
parts of the neck, where they cover the decus-
sation of the longitudinal fibres. In the inter-
val between the ureters, these transverse fibres
are very distinct, particularly above, where they
usually form a very distinct cord, arched a little
upwards: this semilunar band or projection
may be better seen when the bladder is opened ;
it corresponds to the base of the trigone, ex-
tends from one ureter to the other, and is im-
mediately in front of the pouch or bas fond of
the bladder, which is so well marked in the
adult and old. Throughout the rest of the
trigone the circular fibres are by no means so
distinct or strong as they are behind it, or as
they are towards the anterior and lateral parts

of the cervix. This circular plane of fibres may —

next be raised; it is almost impossible to do
this completely, because many of them deviate
from that course, and join into the next or third
lamina, taking a totally different course; the
separation, however, can be accomplished suffi-
ciently to demonstrate the peculiar ariange-
ment of the third plane of fibres, not all over
the bladder, but only in particular situations,
namely, in the greater part of the anterior
and posterior regions, but ouly very imper-
fectly on the superior fundus, and on the
sides, and not at all on the trigone. Wherever
this third layer is exposed, the fasciculi appear
very large and thick, and present a very remark-
able appearance and course, not unlike the
inner surface of the cavities of the heart. Large
fleshy bundles, bearing some resemblance to
the carnee columne, separate, unite again, and
again subdivide, the fibres taking various direc-
tions, and inclosing interstices of the mucous
surface of various size and form: several of the
fibres also join those of the circular plane. It
is owing to this reticularly arranged stratum of
muscular fibres that the bladder, when opened,
presents its peculiar irregular surface, which in
some cases, particularly if the bladder have
been hardened in aleohol, resembles a honey-
comb surface. If the bladder which has been
opened be everted, then carefully closed and
distended, this reticular coat will become very
distinct when the mucous membrane has been
removed. Its action during life must obviously
be to contract the capacity of the bladder in
every direction. When the internal surface of
the bladder, even in the healthy state, is in-
spected, the different orders of muscular fibres
become very apparent; and when this coat has
become thickened from any of those causes which
are well known to produce thickening, some
of the fasciculi often project into the bladder:
such a condition of the organ is named a co-
lumnar state of the bladder. In cases of irritable
bladder, when calculous symptoms have been
present, and the bladder has been sounded in
consequence, these fleshy projections meeting
the extremity of the sound, have in some in-
stances deceived the surgeon into the idea of
the existence of a calculus, and this is still more
likely to occur should there be any gritty mat-
ter adhering to their surface. Some of those
recorded cases of the operation for lithotomy,
in which no stone could be detected, although
the symptoms of the disease previously existed,
may admit of explanation by a knowledge of
this fact. In the bladder of some persons the
muscular fibres do not perfectly cover the mu-

cous surface, particularly if the organ be very

capacious. In such cases the mucous membrane
may be pushed through some of the cells or
meshes of the muscular fibres, and thus a hernia
of the mucous coat be produced ; that is, a small

pouch or purse of this membrane will protrude — :
between the muscular fasciculi, and will be

covered only by peritoneum or by cellular

tissue. This pouch may continue to increase a

in size, because it possesses no power of empty-
ing itself, and the muscular fibres around its
orifice can only contract the latter without

:
,

BLADDER, NORMAL ANATOMY.

affecting the sac itself; hence a process of this
sort may enlarge indefinitely, and has been
known in some cases to have formed a part of
the contents of an inguinal hernia. Pouches of
this nature, for there may be several in the
same individual, sometimes contain calculi, the
latter having probably been the cause of the
former, inasmuch as the muscular coat having
been excited by the irritation of the stone to
increased action, has forcibly pressed the latter
into one of the cells of the mucous membrane,
which has then become enlarged and protruded,
So as to contain the calculus impacted in it.
The consequence of this occurrence to the indi-
vidual, however, is often a fortunate remission
of suffering, because the stone being now fixed
in a cell, ceases to excite pain or irritation: it is
by occurrences of this nature that the boasted
and sometimes fortunate efficacy of certain
lithontriptic medicines as cures for stone is to
be explained.

The exact arrangement of the muscular fibres
at the neck of the bladder has not been very
accurately explained ; some describe them as
arranged circularly so as to constitute a true
sphincter: this opinion is maintained by John
Bell, System of Anatomy, vol. iv. p. 159; also
by Palfin, Anat. tom. i. p.163; by Meckel,
Anat. vol. iii. p. 564;~- by Bayle and others.
Sir Charles Bell also describes a sphincter
vesicz to exist, but places it in a different situa-
tion from that usually assigned. His description
of this muscle is as follows :—* to exhibit it, cut
off all the appendages to the bladder except
the prostate gland, make an incision into’ the
fundus and invert it, dissect off the inner mem-
brane from around the orifice of the urethra ;
a set of fibres will be discovered on the lower
half of the orifice running in a semicircular
form round the urethra ; these make a band of
about half an inch in breadth, particularly
strong on the lower part of the opening, and
having mounted a little above the orifice on
each side, they disperse a portion of their fibres
in the substance of the bladder; a smaller and
weaker set will be seen to complete their course
surrounding the orifice on the upper part, to
_ these sphincter fibres’a bridle is joined which
comes from the union of the muscles of the
ureters ; this is the most posterior part of all
the muscles which embrace the urethra, it re-
sembles the sphincters of the other hollow vis-
cera; forexample, that of the pyloricorifice of the
stomach.”* The great advantage of the sphincter
as thus described must be, as Sir C. Bell says,
to prevent the fluids from the seminal vessels
and from the ducts of the prostate gland, falling
back into the bladder, as also to protect the ori-
fices of these ducts from exposure to the urine
when the bladder is closed, and that without
this arrangement it would be inconceivable how
the contents of the vesicule seminales could be
discharged forwards, or how the urine could be
retained while the seminal discharge was being
made, We must remark, that after frequent
examinations of this region, we cannot satisfy
ourselves of the existence of this particular ar-

_ ™ Treatise on Diseases of the Urethra, &e. p. 14,

383

rangement, although we are convinced that the
orifice is furnished with a sphincter such as we
shall presently describe. Moreover, we believe
that the prostatic secretion is more or less ex-
pressed at each evacuation of the urine, inas-
much as the longitudinal, the principal detrusor
fibres of the bladder, are fixed into, expand
upon, and must compress this gland, especially
at the commencement of the process, although
they obviously can have no effect on the vesi-
culz seminales, vasa deferentia, or their contents.

The existence of a true muscular sphincter
is denied by Sabatier, Anat. tom. ii. p. 403;
Marjolin, tom. ii. p. 473; also by Bichat,
Anat. desc. tom. v. p. 147; by Boyer, Anat.
tom. iv. p. 490; by Cloquet, Anat. tom. ii. p
1050; by Portal, Anat. tom. v. p. 401; the
latter, however, describes the urethral orifice as
surrounded by oblique muscular fasciculi.
Winslow also, Anat. tom. ii. p. 210, denies a
true sphincter, but ascribes the office of such
to the muscular fasciculi which pass from the
pubis to the bladder. Wilson (Lectures on the
Urinary and Genital Organs, p. 57,) denies
the existence of any regular sphincter, but
thinks, from the distribution of some fibres
at the beginning of the urethra, and which pass
round it semicircularly from the forepart and
meet the descending fibres behind, that the
contraction of these, assisted by those of the
urethra nearer the penis (compressores urethra),
may be considered as sufficient to prevent the
urine passing from the bladder into the urethra.
Several of the foregoing writers who deny a
muscular sphincter to the bladder, consider,
nevertheless, that its orifice is closed by a pe-
culiar tissue which resists the ordinary tendency
of the muscular coat to expel its contents, but
which is capable of yielding to the increased
force which is exerted in the ordinary evacua-
tion. Thus Bichat describes, as placed between
the mucous lining and the external cellular
tissue, a dense white fibrous substance, con-
tinuous with the muscular fibres which are in-
serted into it, a small process of this prolonged
posteriorly to the uvula, and another anteriorly
to the verumontanum. This substance is
not muscular, and presents a passive organic
resistance. Cloquet, Boyer, and Marjolin con-
cur in the same account; it is difficult, how-
ever, to reconcile with such a condition of parts
the phenomena which not unfrequently occur
in disease, such as paralysis and incontinence
of urine in cases of injury of the spine, or of the
nervous system; or again, retention of urine
from irritation in this situation caused either by
local inflammation, or through sympathy with
some adjacent diseased organ, or by some pe-
culiar acrimony in the urine. A muscular struc-
ture is more reconcilable with these, and with
many other pathological facts, than an elastic,
or fibrous, or resisting tissue, such as this part is
stated to be furnished with. The result of our
examination convinces us that the organization
of this part is very peculiar, and that the neck
of the bladder is closed by a power more than
thatof a mere elastic tissue. Elasticity no doubt
resides in this structure,and we admit to a con-
siderable extent, as it does in almost every ani-

384

mal tissue, except perhaps mucous membranes:
elasticity exists at the pylorus and at the anus,
although true muscular and sphincter fibres are
evident at both these outlets. When this region
is carefully examined in the male subject, we
shall find that immediately behind the pubis, on
the anterior and lateral reflections of the pelvic
fascia, to these ligaments numerous muscular
fibres of the bladder are attached ; these are
chiefly longitudinal, but there are also several
transverse arched or semilunar, some upon, and
others underneath the longitudinal fibres, and
with which many of them are continuous. None
of these arched fibres pass around or behind the
prostate so as to encircle this region. The longi-
tudinal, the transverse and decussating or inter-
lacing fibres in this situation, are in greater
abundance, and may be raised in successive
lamin. Veins and nerves are very manifest in
and between these; several of the longitudinal
fibres of the deeper laminz pass in so deeply as
to approach the mucous surface. When the
several strata of longitudinal fibres have been
raised from the front and lateral parts of this
region, the circular fibres of the bladder become
distinct, but do not appear so proportionably
imcreased as were the longitudinal; but on de-
taching more completely the longitudinal strata
down to the circumference of the very opening
of the urethra, a distinctly fibrous, that is, mus-
cular tissue, is evident, bounding this opening
laterally and superiorly, but not below. This
muscular fasciculus is not intimately connected
to the general circular coat ; it appears redder,
and of a closer texture, and will be found to be
attached to the fibrous or tendinous substance
forming the anterior part of the trigone on each
side of the uvula, behind which it does not
pass. The longitudinal fibres are inserted partly
mto this semicircular muscle, much in the same
manner as the levatores ani are inserted into the
circumference of the anus. ‘This structure we
consider to be partly elastic, but essentially
muscular; it bounds the urethral opening late-
rally and above, but not below; the slight pro-
jection of the uvula in the latter situation, and
the elasticity and gentle state of contraction
natural to all the sphincter muscles, will pre-
serve this opening in a constantly closed state
during the quiescent and normal condition of
the parts. This arrangement is on a level with
the uvula, and, of course, behind the orifices of
the prostate ducts, although the base of that
gland extends further back than this sphincter.
We have repeatedly examined beneath the
uvula for muscular fibres, but have found none
in a transverse direction ; there is, therefore, no
portion of a sphincter in that spot, and hence
one advantage of the slight elevation caused by
the uvula and by that portion of the prostate
gland denominated its middle lobe, which cor-
responds to it: indeed sphincter fibres in this
spot would be not only useless, but injurious, as
they could scarcely exist without interfering
with the ejaculatory ducts. We conceive, then,
that the urine is retained in the bladder partly
by tie relaxed or passive state in which its
muscular coats usually remain until they are
excited by the sense of distension, partly also

BLADDER, NORMAL ANATOMY.
_by the urine, when only ina moderate quantity,

gravitating, not towards the neck, but distending
the inferior fundus, which lies on a level lower
than that of the former, and principally by the
dense muscular, elastic, vascular, and nervous
tissue which surrounds three-fourths of the
orifice of the bladder. The gentle contraction of ©
the latter raises the uvula into the calibre of the
opening, while the remaining sides are pressed
into contact with it, and thus the bladder is
closed. When distension excites the usual feel-
ing, the muscular coat contracts, the sphincter
relaxes, phenomena exactly corresponding to
those which take place under similar cireum-
stances in the rectum and anus; and as the
levatores ani expand the anal opening by draw-
ing the sphincter fibres outwards at the time
the expulsive powers of the rectum are dis-
charging its contents, so the longitudinal fibres
of the bladder draw out from the axis of the
urethral opening the relaxed sphincter which
encompasses three-fourths of it, while the
middle band of the posterior longitudinal will
plainly depress the uvula and expand the orifice
in that aspect, and will even retract and depress
the verumontanum, thereby freeing the passage
into the urethra, and retracting that sentient
caruncle from the irritating influence of the
urinary stream.

The next coat of the bladder, the fourth of
some anatomists, or the second common of
others, is the deep cellular, or more properly
the submucous cellular coat, by some also de-
nominated the nervous tunic. This coat invests
the whole organ and connects the muscular and
mucous tissues intimately yet loosely ; it con-
tains no adipose matter, but is very filamentous,
extensible, and elastic: in it are found those
vessels and nerves which are to supply the in-
ternal surface of the bladder, and which, except
in some situations, are not very numerous when
compared with those in the other hollow vis-
cera. This coat, though essentially cellular, pre-
sents very many fibrous threads through it, on
which much of its strength appears to depend,
particularly in those places where the muscular
coat is deficient. When the bladder is fully
distended, if we dissect off the muscular fibres
carefully without injuring this tissue, the mu-
cous membrane still remains supported ; but
as soon as a portion of this coat is detached,
the mucous membrane projects in an unsup-
ported sacculated manner. This coat corre-
sponds with that elastic tissue in the parietes
of the small intestines in some animals, out of
which the substance, commonly termed catgut,
is formed.

The third proper coat is the mucous or lining
membrane, to expose which the bladder must
be opened by a perpendicular incision along
its anterior region. This tunic is but a portion
of the genito-urinary mucous membrane, and is
continuous with that lining the ureters above,
and the urethra below. The vesical portion of this
membrane is very thin, has a soft and smooth feel
caused by the mucous fluid which lubricates it ;
its colour is very pale in the natural condition,
although in catarrh or in chronic inflammation
it presents a general vascular appearance; but

'

BLADDER, NORMAL ANATOMY.

in health the mucous surfaces of the intestinal
tube and of this organ form a strong contrast,
more particularly if the vessels of Loth have
been injected with coloured size; the former will
then assume the colour of the injection, the lat-
ter will continue pale, although numerous ves-
sels become apparent in the submucous tissue.
The mucous lining of the bladder in the healthy
“state does not present any distinct follicles or
crypte except near the cervix, which become
very distinct in chronic disease. A cuticular or
epidermoid covering cannot be detected in
health, although in certain states of disease a
substance very similar to cuticle is occasionally
discharged in shreds and flakes. When the blad-
der is empty and contracted, the mucous mem-
brane is thrown into numerous ruge, existing
chiefly in a transverse direction, which are most
distinct if a very recently contracted bladder be
examined. When the organ is distended, these
ruge disappear, so that their existence may be
considened as evincing a want of elasticity in
this tissue. This membrane presents some pecu-
liarities throughout the extent of a small region
named the ‘ trigone’ or the ‘ velum’ of the
bladder: this term is applied to a small triangular
space, nearly equilateral, situated about the
middle of the inferior region, and leading to the
neck of the bladder. The base of this space is a
lunated line ‘leading from the orifice of one
ureter to the other; the sides are marked by
lines which converge forwards from these open-
ings to a slight projection at the neck of the blad-
der named the ‘ uvula,’ which is immediately
behind or rather in the orifice of the urethra.
Throughout the area of this space the mucous
membrane is very smooth and free from ruge
or folds, as it adheres closely to the fibrous or
compact cellular substance beneath: it is also
more vascular, being generally ofa delicate rose
colour, or variegated with fine vessels, and when
minutely examined with a magnifying lens
numerous fine villican be discerned. On the
whole this surface appears to be delicately and
catemegied organized, and no doubt possesses
igher sensibility than the remainder of the in-
ternal surface of the organ. The posterior part
of the trigone is thinner than the anterior ; the
line which marks its base is a thickened band of
the circular or transverse muscular fibres, behind
which the inferior fundus of the bladder is fre-
quently dilated into a pouch which presses
against the rectum, and where a calculus some-
times rests,so as to elude the search of the
sound unless the finger be introduced into the
rectum: in old persons this pouch sometimes

_ remains constantly full of urine, the muscular

coat of the bladder not being able to contract
it. The lines which form the sides of the tri-
gone, and which extend from the orifices of
each ureter to the uvula, are composed of a
slight projection of the mucous membrane, be-
neath which is some cellular tissue, and in
some cases a few pale muscular fibres are dis-
tinetly seen. These lateral lines are not in
tm very distinct, at least in the healthy

der; their distinctness is owing to little

_™ore than being the borders of this space. In

VOL. I.

335

some cases, particularly when the prostate has
been enlarged or the urethra obstructed, they
are found very distinct, the muscular fibres
they contain being thickened even in a greater
degree than the other portions of the muscular
coat of the bladder. These lateral fasciculi
appear to be little more than some of the lon-
gitudinal muscular fibres of the bladder con-
verging towards its cervix. Sir C. Bell,
however, has attached a particular importance
to these muscles, which he denominates the
“muscles of the ureters:” his description of
their attachments and use is as follows, in his
own words :—* The use of these muscles is to
assist in the contraction of the bladder, and at
the same time to close and support the mouths
of the ureters.” “They guard the orifices of
the ureters by preserving the obliquity of the
passage, and by pulling down the extremities of
the ureters according to the degree of the con-
traction of the bladder generally.” *

It appears very questionable how far this
statement as to the structure of these lines is
generally correct, and it is still farther doubtful
whether the use assigned is correctly ascribed
or not; for it may be remarked that these lines
are often very faintly traced, that the muscular
structure within them is sometimes very in-
distinct, that in females it is scarcely observable,
in very young children also of either sex it is
not well developed ; whereas if such an import-
ant office as that of guarding the ureters de-
pended on these muscular fibres, it is most
probable, and indeed is even certain that their
presence would be constant and their deve-
lopment more uniform. Again, the fact of the
dead bladder when fully distended with fluid, or
even with air when the urethra is tied, and the
contents not escaping through the ureters, is a
strong proof that the oblique or valvular direc-
tion of the latter is the true cause of the non-
regurgitation, and that it does not depend on
the contraction of any particular muscular
fibres. Again too, in animals this structure, as
described by Sir C. Bell, is not at all obvious
although the ureters have the same oblique
course as in man ; it would rather appear that
these muscular bands, which are occasionally
very distinct along the sides of the trigone, are
only portions of the longitudinal fibres, and
that their action will be to shorten the trigone,
to draw its base forward, and thus to assist in
emptying the bladder. They may doubtless assist
in fixing the orifice of the ureters and moving
these in proportion as the surrounding parts are
affected, but the opinion that the preservation
of the valvular or oblique course is depending
upon them appears to be invalidated by the fore-
going remarks, as well as by the following expe-
riment. The healthy bladder of an adult male,
recently dead, was opened to a small extent on
its fore-part, and the sides of the trigone were
cut by a sharp-pointed bistoury passed beneath
each of them ; the urethra was then tied,and the
bladder carefully closed: its cavity was next
fully distended with water, and the fluid was

* Medico-Chir. Trans. vol. iii. p. 178.
2¢

386

retained for a considerable time although it was
subjected to pressure, and was afterwards eva-
cuated through the urethra when the ligature on
the latter was removed. No alteration whatever
from the ordinary appearances was observed
either during the distension or the subsequent
emptying of its cavity, nor did any regurgi-
tation take place into the ureters in either
state. The same experiment with air instead
of water was repeated and with the same effect.
It may be further observed that the ductus
communis choledochus enters the duodenum in
a similar oblique way, that no regurgitation
from the intestine ever occurs into it, and yet
there is no peculiar muscular fasciculus attached
to its orifice which could execute the office
ascribed to these lateral boundaries of the tri-
gone. To these muscles Sir C. Bell also
attributes the projection into the bladder of the
third lobe of the prostate gland, usually called
the middle or Home’s lobe, when this part is in
a state of enlargeinent. There are, however, such
plain and simple reasons for this tumour be-
coming prominent in this direction rather than
in any other, that it is unnecessary to search for
an explanation in the action of these muscles,
the undoubted development of which in such
cases may with a much greater degree of pro-
bability be considered as one of the effects and
not as the cause of this projection.

The uvula or apex of the trigone varies very
much in its appearance in different persons.
In the normal state it is very small, and is
most distinctly seen by making only a small
opening in the upper region of the bladder
when in situ, and looking down towards the
cervix ; it then appears as a small projection
in the middle line of the orifice of the urethra,
which opening it thus assists to close or to fill.
It is much effaced by opening the bladder from
the urethra after its removal from the subject,
the mucous membrane being then easily ex-
tended. This projection is only a slight full-
ness or prominence of the mucous membrane
with an increase in the submucous tissue, in
which small follicles or crypte may be dis-
cerned. This part appears rather vascular, and
probably possesses some peculiar organization ;
the situation also which it holds, as well as its
structure, appear to indicate it to be the seat of
a proper sensibility, which, when affected, ex-
cites the irritability of the whole organ. Many
facts which manifest themselves in the treat-
ment of urinary diseases seem to corroborate
this idea: thus, when a calculus is pressed
against this part of the mucous membrane, the
pain is insupportable, whereas when it falls or
is directed into the inferior fundus, the pain is
comparatively trifling; also when a bougie or
catheter is being passed into the bladder, a
peculiarly acute sensation is experienced as the
Instrument comes in contact with this par-
ticular prominence. The uvula in the child is
the most depending part of the bladder, at
least in the erect posture; this is not the case
in the adult; hence probably we have in part
the reason why calculus is more painful in the
former than in the latter.

BLADDER, NORMAL ANATOMY.

The trigone in the female bladder comprises
asmaller area, but is broader in pr i
than in the male; it is not so distinct or firm
in the former as in the latter, where it issup-
ported not only by a dense substratum, but
also by the vasa deferentia, vesicule seminales,
and prostate gland. This portion of the
bladder is so firm and incompressible that it is
probable the cavity corresponding to it can
never be wholly obliterated, so that in the most
contracted bladder a few drops of fluid are
still retained; The uvula, like other similar
portions. of the mucous membrane, is subject
to infiltration and increase of size in acute in-
flammatory affections, as also to chronic and
permanent enlargement; and as it lies nearly
over, but a little anterior to the middle lobe
of the prostate gland, it is therefore difficult,
and in most cases impossible to distinguish
affections of the latter from those of the former.
The uvula is smaller in the female than in the
male; hence the opening from the bladder into
the urethra is larger in the former than in the latter.

Organization of the bladder.—a. Arteries.—
In the normal state the bladder is not very
vascular; we have already mentioned that its
inner surface is pale and free from any red
vessels. The arteries, however, of the bladder
are very conspicuous when they have been in-
jected; they are long and tortuous, and are
distributed chiefly along the sides, inferior
region, and cervix. They are derived from
various sources. The internal iliac or hypo-
gastric on each side, just before its ligamen-
tous termination, sends off one or two vesical
branches, which ramify on the superior and
lateral regions ; the middle hemorrhoidal and
internal pubic also very generally send some
considerable branches to its inferior region and
cervix; the obturator and epigastric vessels
also very frequently send small arteries to it
anteriorly. When the bladder is distended, all
these vessels are seen very distinctly, and in
the muscular coat much more than in the sub-
mucous tissue, contrary to what may be ob- ~
served in the other hollow viscera; this, how-
ever, is accounted for by recollecting that the
mucous coat of the bladder does not in its
normal and healthy condition possess, nor does
it indeed require any high degree of organi-
zation, as it is simply a reservoir, and has no
important function to execute further than to
secrete a fine mucous fluid which lubricates its
surface and defends it from the irritation of the
urine. This secretion mingles with the urine,
the properties of which it alters in a remark-
able manner whenever it is increased in quan-
tity, as occasionally occurs in chronic disease —
of this organ. The muscular coat of the blad-
der is the essential agent in expelling its con- —
tents, and is therefore more fully supplied with
vessels than any other of its tunics. rt

b. Veins—The veins of the bladder a
large and numerous inferiorly, and in old per-
sons in particular. There are but few on th
superior and lateral regions except towards the
inferior part of the latter. In the child the
veins are very inconsiderable: this difference —

CS lee

vertical direction than in the adult.

BLADDER, NORMAL ANATOMY. 387

depends on this circumstance, that the veins
which are seen at the inferior region of the
bladder, and which return the blood from its
tunics, do not belong exclusively to this organ,
but are principally derived from the dorsal
veins of the penis; they also receive several
branches from the vesicule and the prostate,
also from the rectum and intervening adipose
substance. In the adult and old these latter
veins are very numerous, indeed they may be
said to form a perfect ‘ venous plexus’ on each
side, extending from the termination of the
ureter to the prostate gland. All these veins
are considerably less developed in children,
inasmuch as the organs, at least those of gene-
ration, from which they are principally de-
rived, are comparatively small. The vesical
veins ultimately discharge their blood into the
internal iliac or hypogastric veins.

c. Lymphatics—The lymphatic vessels are
tolerably distinct, more particularly inferiorly
and about the cervix. They intermingle with
the lymphatics of the rectum and of the neigh-
bouring organs, and ultimately lead to the
internal iliac or hypogastric glands. Indepen-
dent of dissection, the existence of absorbents
in the bladder is proved by its functions, or
by the changes which the urine undergoes
when long retained in this cavity,—a portion
of its water is absorbed, and the residue be-
comes pungent, high-coloured, and acrid.

d. Nerves.—The nerves of the bladder are
derived from the hypogastric plexus, which is
constituted of two orders of nerves, viz. some
from the sacral plexus of the spinal system,
and others from the sympathetic or ganglionic
system. This two-fold supply of nerves accords
with the functions of this organ, and entitles it
to be placed, as far as relates to the properties
of its muscular coat, among the mixed muscles,
being in part voluntary and in part involuntary :
the former endowment will, of course, depend
on its share of spinal nerves, the latter on the
sympathetic. It may also be observed that the
branches of the latter are principally distri-
buted about the cervix and inferior region,
while those of the former are seen distinctly
on the sides and superior regions; but in all
these situations these nerves are more or less
intermingled.

The cervix of the bladder is of a com-
pressed conical form, longer below and on the
sides than above. It is surrounded in the male
by the prostate gland ; only a small portion of

is is upon its upper surface: in the adult the
neck is placed nearly horizontally below the

bis and behind the triangular ligament.

n the female the cervix vesice is closely sur-
rounded by a whitish compact follicular tex-
ture, not possessing any perfect capsule, and
therefore without the accurate form of or any

_ resemblance to the prostate gland in the male.

The cervix in the child is more distinctly
conical, and is placed in a more oblique or
The term
cervix is not very definitive, as there. is no

_ exact limit, at least in the human subject, to

mark this region as in quadrupeds ; according

to most writers on human anatomy, it is syno-
nymous with the prostatic portion of the
urethra, and the full description of it is given
by such in connexion with the anatomy of the
urethra. We consider the neck of the bladder
to be that contracted portion of the viscus
which is embraced by the base only of the
prostate gland, and which contains internally
and below the slight elevation named the
uvula of the bladder, and laterally and above
the peculiar structure which fulfils the office
of a sphincter.

Having particularly noticed the situation of
the bladder, and the slight change of position
it admits of in consequence of its change in
form, we shall next consider its attachments,
or the media by which it is retained in its posi-
tion, for it may be considered as nearly a fixed
viscus. The bladder is held in its position
principally by three connexions; first, by the
peritoneum ; secondly, by the reflections of the
pelvie fascia; and, thirdly, by the continuity
of its cervix with the urethra, the commence-
ment of the latter being fixed by ligamentous
connexions to the arch and rami of the pubes.
First, the bladder is connected by certain folds
of the peritoneum to the parietes of the pelvis
and abdomen; these folds are named the
*¢ false ligaments” of the bladder, and are five
in number, two lateral, two posterior, and one
superior. Each of the lateral ligaments or
folds extends from the lateral region of the
bladder to the iliac fossa, and contains in its
duplicature the vasa deferentia in the male, and
the round ligament of the uterus in the female.

The posterior folds or ligaments are also two
in number; they lead from the fore-part of
the rectum to the back part of the bladder.
Each of these folds is of a semilunar form,
(the concavity looking forwards and upwards,)
and contains the ureter posteriorly, and the
obliterated hypogastric artery anteriorly. When
the bladder is distended, these posterior folds
are very short; but when it is contracted, they
are distinct and long. Between them the pelvic
cul-de-sac of the peritoneum descends, which
in the empty state of the bladder and rectum
appears deep, narrow, and distinct, but in the
distended condition of these organs, particu-
larly of the former, it is of much less extent
and depth, as the bladder in becoming dis-
tended rises upwards and draws with it the
cul-de-sac of the peritoneum: hence in the
distended state of this organ the triangular
portion of its inferior region which is uncovered
by peritoneum is increased in extent, and is
larger than when the organ is contracted.
Between the two posterior ligaments one or
two semilunar folds of the peritoneum may
be generally observed on the posterior surface
of the bladder, provided the latter be in a con-
tracted state; these folds are expanded as the
bladder enlarges, and thus they serve to ac-
commodate the serous membrane to the varying
conditions of the bladder without stretching or
extending the former—a purpose which perito-
neal folds or ligaments in general are intended

to answer. ;
; a

388

The superior fold or ligament extends from
the summit of the bladder to the posterior
surface of the recti muscles, and is partially
reflected over the remains of the urachus and
hypogastric arteries. This fold rather consists
of three folds which diverge below and con-
verge towards the umbilicus; they present a
falciform appearance towards the abdomen,
eoany when the bladder is contracted.

n the foetus these superior folds, particularly
the lateral, are very distinct, as they each con-
tain the umbilical artery. The urachus, which
is in the centre, is also at that age very distinct
though shorter; its vesical end is often pervious
for about an inch: it is always closed before it
arrives at the umbilicus, it then becomes fila-
mentous, and is soon lost on the umbilical
arteries.

The second medium of connexion between
the bladder and the parietes of the pelvis is
the vesical fascia, the reflections of which con-
stitute the true ligaments of the bladder. The
vesical is the internal lamina of the pelvic
fascia reflected from the latter at the upper
border of the levatores ani muscles: it covers
the internal surface of this muscle on each side,
and descends as low as a line drawn from the
inferior border of the symphysis pubis to the
spinous processes of the ischia, On this level
it is reflected on the prostate gland and on
the sides of the bladder, and posterior to this
organ on the rectum and on several of the
pelvic vessels and nerves. The anterior or
vesical portion of this fascia is distinct and
strong, and forms a pouch on each side of the
bladder which assists in closing the pelvis;
posteriorly this fascia is thin and cellular, being
perforated by several vessels. Its anterior
reflections constitute the true anterior liga-
ments of the bladder, which are described as
arising from the lower margin of the pubis on
either side of the symphysis, then passing back-
wards and upwards on the upper surface of
the prostate gland, and expanding on the an-
terior region of the bladder; many of their
fibres become continuous with the muscular
fibres of the bladder.. A depression exists
between these two ligaments, along which the
dorsal veins of the penis run from beneath the
arch of the pubis to the side of the bladder
in their course to the internal iliac veins, in
which they terminate. The fascia, however,
is not deficient in this depression between these
ligaments, but is continued from one to the
other so as to line this hollow and to cover the
upper surface of these veins. The anterior
ligaments present a smooth concavity towards
the abdomen or pelvis; their perineal or infe-
rior aspect is convex, and has inserted into it
the posterior lamina of the inter-osseous or
triangular ligament of the urethra.

The true lateral ligaments of the bladder are
also two in number, one on each side; each is
continuous with the anterior, and is formed by
the reflection of the vesical fascia from the
internal surface of the levator ani muscle to
the side of the prostate gland, and of the
bladder immediately above and outside the

BLADDER, NORMAL ANATOMY.

vesicule seminales. The pelvic ‘and vesical
fascize will be more particularly noticed in the
article Penvis. .

Lastly, the bladder is retained in situ by
the attachments of the cervix; these take place
not only directly by the ligaments which have ;
been just described, but also indirectly through *
its connexion to the urethra and of the latter %
to the pubes through the medium of the trian- 5
cular ligament of the urethra. This ligament,
for a fuller description of which we refer to 4
the article PERINEUM, is a strong aponeurosis :
intimately connected to the rami of the pubes
and ischia, and there continuous with the obtu-
rator fascia of each side. It is strong, tense,
and unyielding, and closes all the anterior
portion of the inferior orifice of the pelvis; it
is perforated by a small opening, through whieh
the urethra passes about an inch inferior to the
bony edge of the pubes; the edges of this
opening are continued on the urethra both to-
wards the perineum and towards the pelvis.

The process which extends in the former or
inferior direction is lost on the bulb of the
urethra, while that which extends in the pos-
terior or superior direction, and which is more
distinct and strong, encompasses the mem-
branous part of the urethra, (which, while in

situ, is very short,) and is then inserted or
becomes continued into that reflected portion

of the vesical fascia which forms the true
anterior and lateral ligaments of the bladder ;

thus the commencement of the’ urethra, the
prostate gland, and the neck of the bladder, |
which must be nearly synonymous with the |
prostatic portion of the urethra, are all retained

in a nearly fixed position, and the continuity |
of the different aponoreuses in this region |
serves to afford mutual strength and general
security.

The bladder, notwithstanding the foregoing
connexions, is subject to displacement. In the
male this occurrence seldom happens, although
in some cases of very large inguinal or scrotal
hernie this viscus has been gradually drawn
into the sac, in consequence, most probably,
of adhesion between it and the omentum or
some other of the protruded parts. We have
already mentioned how a portion of the lining
membrane may become protruded between the
muscular fasciculi and form a sac which may
increase to a considerable size, and extend into
some new and even remote situation. In the
female the bladder is very liable to partial
pressure as well as to displacement, owing to
different conditions of the uterus, such as
retroversion, inversion, and prolapsus.

BIBLIOGRAPHY. — Mangetus, Ureterum et ve-—
sice urinarie hist. ex variis in Bib. Anat. v. 1.
Vogelmann resp. Janson, Diss. sist. fab. &e. renum
et vesice urinarix, 4to. Mogunt. 1732. Parsons, —
Description of the human urinary bladder, &e. 8vo. _
Lond.1742. Beudt, De fabrica et usu viscerum urop
eticorum, 4to. Lugd. Bat. 1744 (Ree. in Hal
Disp. Anat. vol, iii.). Walther, De collo vi
vesice, 4to. Lips. 1745 (Rec. in Haller, Coll. ¢
Anat. vol. v.). Léeutaud, Obs. anat. sur la structur
de la vessie, Mém. de l’Acad. de Paris, 1753.
Weitbrecht, De figura ct situ vesice urinariz, Com. —

3)

BLADDER, ABNORMAL ANATOMY.

Petrop. vol. v. Noot, De structura et usu vesice
urinarie atque ureterum, 4to. Lugd. Bat. 1767.
Boeckhoven de Wind, De ureteribus et ves. urin.
4to. Lugd. Bat. 1784. Richerand, Mém. sur |’ap-
pareil urinaire, in Mém. de la Soc. Méd. d’Emulat.
An viii. Bell on the muscles of the ureters, Med.
Chir. Trans. vy. iii. Wilson, Lectures on the struc-

BLADDER, ABNORMAL ANATOMY
OF THE URINARY.—Under this deno-
mination it is proposed to include all variations
from the natural condition of the organ, whe-
ther the particular variety be a congenital vice
of conformation or a consequence of extra-
uterine disease.

Numerical . .

{Congenital . .

Changes . . <

| Acquired . . she

To some persons, the introduction of two
functional diseases, paralysis and spasm, in
an article on pathological anatomy, may appear
objectionable ; but as they are sometimes con-

i Sequences of structural change, we hold that
] we have a perfect justification for their ap-
pearance.
CONGENITAL CONDITIONS.
_ Numerical changes.—Absence—Among the
single organs of the body, one degree of nu-
merical diminution only is possible, namely,
their absence. Such an anomaly, if we except
true cases of monstrosity, should be extremely
rare, and indeed it is so; for as all unique
portions of the organization are called upon
to perform functions, to which they are more or
less exclusively devoted, it is rately that any
other can supply their place, and in conse-
quence, when the organ is wanting, the func-
tion is also wanting.
_ There are upon record a certain number of
instances of absence of the urinary bladder ;
in some of these cases the ureters have been
found to terminate directly in the urethra, in
__ others they have been inserted into the rectum,
_ in others they have communicated with the
hy vagina. Of the first species we have the fol-
ng examples: Lieutaud * mentions the
case of a man, aged thirty-five, in whom the
ureters, the capacity of which was much aug-

% * Hist. Anat. Med, Liber primus. Obs. 1361.

Of conformation

~ Of conformation

Of position

Of structure ....

_Of function . .

389

ture and physiology of the male urinary organs, &c.
8vo. Lond. 1821. See also the different systems
of anatomy, the Tabulx Septendecim of Santorini
and his Observationes anatomice, and the recent
Memoir of Mr. Guthrie on the anatomy and diseases
of the neck of the bladder, &c. 8vo. 1834.

( R. Harrison.)

In the following synopsis may be seen the
several affections included, as well as the order
in which they will be described in the present
article.

Absence.
we } Plurality.
Septa.
ae ; Extrophy or extroversion.
Persistance of the urachus.
Sacculi or cysts.
ar increase of.
see decrease of.
Introversion.
Hernie, inguinal.
Semoral.
io ; perineal,
vaginal.
(Inflammation with its consequences..
Idiopathic softening,
Rupture.
Fistule.
Hemorrhage.
Fungoid tumours.
Varices.
_ Scirrhus.
§ Paralysis.
" * USpasm.

mented, terminated immediately below the
pubis near the orifice of the urethra. Binnin-
ger* describes the case of Abraham Clef, in
whom there was no urinary bladder, and the
ureters opened upon the urethra. A stylet,
introduced into the urethra, passed alternately
into the one and the other ureter; the ureters
were afterwards separated from the kidneys,
and the stylet, introduced in the opposite di-
rection, met with no obstacle to its passage into
the urethra.

Of the second species we have, in the se-
venth volume of the Philosophical Trans-
actions, the history, given by Richardson, of a
lad residing in Yorkshire, who lived to the age
of seventeen, without ever having passed urine
through the urethra, and who had still enjoyed
good health. The only inconvenience he suf-
fered was a consequence of the passage of the
urine into the rectum, by which a troublesome
diarrhea was kept up. Camperft speaks of
five similar cases, one of which was that of
a female. Klein{ also speaks of a case. In
the Noy. Acta Acad. Nat. cur. ann. i. obs. 38,
there is another in which “ ureter in rectum
intestinum insertus fuit.’” And in the Hist.
de l’Acad. ann. 1752, n.4, there is one de-.

* Obs. Med. 24, cent. 2.

+ In Mem. pour le Prix, &c. 8vo. edit. tome v.
p- 9.
¢ Rachit. congenit. Nov. Eph. Ac, Nat. Cur.
vol, i. obs, 38,

A

390

scribed under the head; “ Uretra in intestinum
patens.”’

Of the third species, cases are cited by
Haller* and by Schrader.+ In these cases there
was no other malformation. In the foregoing
enumeration we have purposely avoided the
introduction of cases of general monstrosity in
which the urinary bladder was absent.

Plurality.—There are upon record a certain
number of cases in which two or more urinary
bladders are said to have existed. Of these
some appear to me to have been cases in which
the plurality was maintained merely because
the organ was divided into compartments,
either as a consequence of arrested develop-
ment or of the formation of pouches, by the
protrusion, or hernia of the mucous membrane
of the organ. The following case related by
Blasius belongs, I apprehend, to the former
species. A person died phthisical, having a
** double bladder.” When the external sur-
face was examined, it appeared to be an unique
organ, but upon being opened a membranous
septum was discovered, by which the organ
was divided into two distinct cavities. The
narrator adds, that by dissection he separated
the one from the other, so that the longitudinal
septum was formed by the parietes of the two
bladders, which were in contact, and had
become united the one to the other. There is
a case of a similar nature described by Brom-
field; and many more are recorded by Mor-
gagni and others.

We know of no instance in the human sub-
ject, with the exception of that related by
Molinetti,{ in which a plurality of urinary blad-
ders distinct from each other existed. In this
case there does not appear to have been any
thing abnormal in the organisation except in
so far as concerned the urinary organs. “A
woman had five urinary bladders, as many
kidneys, and six ureters, two of which were
inserted into a bladder which was much
larger than the others!! the remaining four
ureters terminated in as many small bladders,
which poured their urine by particular canals
into the larger bladder.” Another but less
carefully described case of the same kind is
mentioned by Fantoni, in his Anat. Corp. Hum.
diss. 7; and in the Acta Physico-Medica
Academiz Cesaree Nat. Curios. vol. i. obs.

* Element. Physiologiz, vol. vii. p. 297.

t Nov. Ephem. Acad. cur. Nat. vol. i. obs. 38,
et die 42, obs. 68. [The Editor has in his posses-
sion the preparation of a female foetus which lived
some days, where the ureters opened through the
abdominal parietes on each side of the pubic region
in the form of little pouches or sacs, in which was
a continuation of their lining membrane. The
urine, as it distilled from the kidney, accumulated
in each of these sacs (in very small quantity, as
they were incapable of containing more than a
drop or two,) prior to its oozing out upon the raw
cutaneous surface. This latter was deficient of
cuticle for a surface about an inch and a half in
diameter ; the pubic bones and the inferior fourth
of the recti and tendinous expansions of the obliqui
were absent. There was also only about an inch
of large intestine (coecum ).—ED. ]

Dissert. Anat. Pathol. lib. vi. cap. 7.

BLADDER, ABNORMAL ANATOMY.

83, may be found a well-marked case of
duplicity of the urinary bladder described by
Zuinger, whose account is accompanied by a
late, which perfectly confirms the description ;
but this case occurred in an ox. : ;
Septa.—Occasionally, within the cavity of
the bladder, more or less perfect septa are
found, by which that organ is divided into two
or more compartments. This condition is met
with or occurs under two very different cireum-
stances: in one it is a congenital affection,
and this it is our business to consider in this
section; in the other it is produced by and is
not an uncommon consequence of retention of -
urine during extra-uterine life. In the de- ;
scription of these two very dissimilar affections
much confusion has occurred, in consequence
of an almost universal impression that they
were similar the one to the other. If the
theory of the eccentric development of organs,
proposed by Geoffroy St. Hilaire, and extended
by M. Serres, be admitted, all difficulty in
explaining this seemingly singular congenital
phenomenon vanishes. M. Serres conceives
that he has triumphantly established the fact,
that the hollow organs, which are single and
placed on the median line, are composed of
two moieties, primitively distinct and sepa-
rate; so that according to him, at a certain
period of uterine life, there exist two aortas,
two basilar arteries, two superior cave, and
so on. Now if there exist two vagine, two
bladders, two uteri, at a certain epoch of
embryotic life, the evolution of these organs
should necessarily present three successive
periods: a first, characterised by their du-
plicity and their complete isolation; a second,
by their mutual approach and union upon the
median line; a third, by their complete fusion,
which constitutes their permanent condition
in man and the mammalia. We can therefore
conceive that at the moment of the second
period, when the two primitive organs are
united, the parietes of both being entire and
in contact on the median line, there will be
a perfect septum separating the one organ
from the other. At the commencement of
the third period in the process of develop-
ment, the septum is destined to disappear,
the two cavities merge into one, and the
work of development in the organ is com-
plete. Now, in the evolution of all the organs,
development may be arrested at any period of
its progress: it may be arrested before the
organs come into contact, in which case there
would be two bladders; it may be arrested
after they have formed a junction, in which
case a complete septum would exist, as in the
case described by Blasius; or the check may __
not occur until a greater or less portion of the
septum shall have disappeared. ;
To distinguish the congenital affection which
is a consequence of arrested development, —
from the acquired affection which is an extra-
uterine disease, and is commonly an effect of
retention of urine, is not difficult. In the
former we shall always find that the entire
of each pouch is invested by a layer of mus-
cular fibres ; in the latter, it will be found that

—) held) gp -

BLADDER, ABNORMAL ANATOMY.

in one of the two compartments no such mus-
cular investment is present.

Extrophy or extroversion—Extrophy of the
bladder was, up to a comparatively late period,
almost universally regarded as a hernia of
that organ; and it was not until about the
middle of the last century, and after Tenon
had dissected two such cases, that this opinion
was shown to be erroneous.* Tenon dis-
covered that there was a complete “ absence”
or destruction of the whole of the anterior
parietes of the bladder; and that the tumour
which is found at the hypogastrium is only
the posterior parietes of this sac, with the
“ trigone” pushed forward by the abdominal
viscera, as if for the purpose of blocking up
the opening caused by the deficiency of sub-
stance below the umbilicus. On the surface
of the tumour which is there presented, and at
its inferior part, we see the urine almost con-
tinually exuding through two holes, pierced in
the centre of two small nipple-like eminences,
which are the orifices of the ureters. The
insertion of these conduits of the urine at the
inferior part of the tumour indicates that the
portion of the bladder, which appears upon
the exterior, is precisely that which, in the
natural state, is found most deeply situated in
the pelvic cavity, the internal surface of the
a and inferior portion of the organ.

e researches of anatomists have most posi-
tively confirmed these indications, by shewing
that in extroversion of the bladder the anterior
part of this organ is more or less completely
wanting, and that the posterior part is pushed
from behind forwards, through the large open-
ing which results from this absence, causing
a “hernia,” either between the two pubes
and the two recti muscles, or, which is very
rare, only between the latter, the mucous mem-
brane being presented externally. By this
displacement the external posterior surface of
the bladder forms a concavity in which some
portions of the intestinal tube may be impacted,
as in a true herniary sac, especially when the
abdominal muscles and the diaphragm are
strongly contracted. The volume of the tu-
mour is on this account variable, not only as
between one subject and another, but in the
same subject at different ages. Thus in new-
born infants onlya slight projection is presented:
the tumour may not occupy a larger space
than from half an inch to an inch. In adults
it May project to the extent of two or more
inches and present a transverse diameter of
four or five. The tumour is then smooth and
frequently appears divided into two lobes.

hen extroversion of the bladder exists, the
umbilicus commonly is, as in the embryo and
the young fetus, not far removed from the
symphysis pubis, nor consequently from the
vesical tumour. The umbilicus is almost
always found immediately above the tumour.
Sometimes, however, the superior extremity of
the latter is observed beyond the umbilicus,
which is then entirely concealed ; and in con-

aa des Sciences, 1761, tom. cxiv, in 12mo.
p- *

391

sequence of this circumstance, some author
have believed that the umbilicus was not pre-
sent in infants affected with extrophy, and they
have drawn from this fancied absence phy-
siological consequences as erroneous as the
— upon which they were based are ground-
ess.

This affection was until recently supposed
to occur only very rarely in the female; this
opinion, however, is incorrect. In many of
the cases on record the sex is not specified,
and it is not improbable that many women
may from a sense of shame be desirous of
concealing such a disgusting deformity. Even
with these reasons why the cases should be less
numerous, we have been enabled to -collect
twenty-one examples. In women the affection
does not produce so much derangement in the
sexual functions as when it exists in- man,
by whom, the penis being almost constantly
deprived of urethra, fecundation must be al-
most impossible. In the other sex, on the
contrary, the vagina being ordinarily free,
though more or less contracted, coitus may
have place, as in a well conformed female,
and fecundation may follow, as in the case
detailed by Drs. Huxham and Oliver and Mr.
Bonnet, of a woman who lived at Lantglasse
near Fowey ;* and that of Thiebault, in which
the delivery occurred through the perineum.
Among the anatomical varieties by which it is
accompanied, none are more singular than that
mentioned by Bartholin,t in which there was
neither anus nor penis, all the ingesta return-
ing from the mouth during forty years.

It has been over and over again maintained
that this affection was incompatible with long
life. The child of which Highmore speaks}
was ten years old, and in good health; the
case of which Montagne speaks$ was at the
time a person of thirty; that of Flajani]|
was seventy. Baillie,{] Mowatt,** Innes,++
and Labourdette,{{ all describe the cases of
adults. Quatrefages§§ describes the cases of
a person of forty-nine and of another of forty-
Six.

Most authors who have written on this sub-
ject have strenuously maintained the constancy
of the separation of the bones of the pubis.
Duncan, even in spite of the case of Mr.
Coates, with the details of which he was fami-
liar, retained that opinion apparently unshaken.
We are in possession of the particulars of
cases in which no such separation existed, re-
corded by Coates,|||| Denman, Roose,{/]

* Phil. Transact. vol. xxiii. 1723, p. 408, 413,
and vol. xxxiii. p. 142.
t Hist. Anat. cent. iv. hist. 30, p. 293.
¢ Disquis. Anat. part iv. cap. 7.
Fe des Sciences, tome cxiv.
|| Malattie Spettanti alla Chirurg. 1786.
{| Morbid Anat. p. 309.
** Mem. de Desgranges.
tt Arch. Génér. vol. ii. p. 286.
¢ Journal de Sedillot.
i Theses de Strasbourg, 4to. 1832.
|

in 12mo.

Edinburgh Med. and Surg. Journal, vol. i.
De nativo vesice urimarie invers. &c,

p- 19.

3892

‘Walther, and one of Quatrefages;* and there
are still one or two others, about which some
doubt exists. What proportion these cases
would bear to those in which the separation
‘was demonstrated, it is almost impossible to
determine, because there can be no doubt that,
of the numerous recorded cases, many of the
descriptions appertained to the same indivi-
dual, the total number of cases being in my
opinion much less than is supposed. It is
easy to explain how this source of error has
been introduced. The unfortunate persons
who are subjected to this infirmity are often
objects of general curiosity. They wander
from town to town for the purpose of obtaining
a livelihood by exhibiting themselves to me-
dical societies and to private individuals, and
the history of a single person may thus be
found repeated in the different periodicals of
the same and even of different countries. ,

To determine the mode in which this vice of
conformation is effected is very difficult. We
cannot admit that Duncan’st explanation of the
mode of its formation is correct, because it is
opposed to every principle which we are ac-
customed to recognize as presiding over the
developement of our organs. He attempted
to prove that an obstacle to the expulsion of
urine affords a satisfactory explanation of this
phenomenon, and he believed that the bladder,
by its distention, removes the bones of the
pubis from each other, ruptures the hypogas-
trium, and then disorganises itself. - We should
have conceived thata very little reflexion would
have removed from his mind so singular an
opinion. The disease is almost always. conge-
nital, although during intra-uterine life the
feetus can have but little urine to void, and
cannot, consequently, have a distended blad-
der. Duncan himself, howéver, strangely
enough states the case of a little boy who was
affected by the disease, although the urethra,
placed in front of the root of the penis,
strongly curved towards the anus, allowed of
the easy passage of the renal secretion. And
there are cases on record well authenticated,
where no separation of the pubis existed.
Isenflamm also states that the disease was
manifested, in his experience, ten weeks after
birth. The opinion of Duncan, therefore,
cannot, it is apprehended, be sustained.

Those persons who believe this disease to be
a primitive monstrosity are divided into two
classes. The one suppose it to be merely an
organic deviation, in which the urethra is
placed above instead of gliding beneath the
pubis. This, however, is not the prevailing
doctrine; that which has obtained the most
general currency is based upon the theory of
arrested development. Supposing that the
two moieties of the body do not, until late,
meet upon the median line anteriorly, they
say, if, by any cause, the sides of the hypo-
gastric parietes cease to advance, the one to-
wards the other, during their allotted time,
the bladder will pass between them, and will

* Theses de Strasbourg, 1832. °
'+ Edinburgh Med. and Surg. Journal for 1805.

BLADDER, ABNORMAL ANATOMY.

soon lose its anterior moiety, su

powerful are the authorities by which this mode :

moiety to be already formed, from whence the
fungous state which it offers after birth. So

of explaining the phenomena is supported, so.
completely is it said by the ardent supporters
of teratology to be in consonance with its
principles, that it would appear to be almost _
heretical to support a somewhat different view
of the subject taken by M. Velpeau. He be-
lieves that extrophy of the bladder is not
simply owing to an arrested development,
first, because in the normal state the bladder
is neither split nor open, neither anteriorly nor
posteriorly; secondly, because the pubic circle
is completely formed before the bladder is per-
ceptible; thirdly, because the aspect of the
fissure that the urinary sac should present
never exists; and, fourthly, because the theory
in question has for its support only such ana-
logies as do not appear to us to have been :
completely established. If an hypothesis be
required, it appears to be more in conso-
nance with observation to assume that this ;
vice depends upon an alteration of the abdo-
men, either pathological or purely mechanical,
contracted during embryo life. The parietes
of the abdomen are extremely attenuated and
fragile up to between the second and third
months, and for some time beyond this the
parietes do not acquire any thing like the
density below that they do above the umbilicus.
At this time the space is so small between the ;
umbilicus and the sexual organs, that the
smallest fissure may become the origin of a
large ulceration, and such lesions are seen at 4
all degrees. Indeed it is scarcely possible to
set forth the variety of lesions to which the
young fceetus is subject: foetuses have been
seen in which the parietes of the abdomen
were alone destroyed. In one of three months
the bladder was already comprised in such a
perforation, and the borders of the whole weie
so jagged, thin, and unequal, that it could be
referred to nothing else than a laceration. It
is held in this place, therefore, that extrophy is
frequently a disease, or the effect of a diseases,
but not a monstrosity; an ulceration, a perfo-
ration of the penis or of the hypogastrium,
being the common point of origin. The
bladder is only secondarily altered. If the
foetus continues to live, the borders of the de-
stroyed bladder are united to the circumference
of the abdominal opening, or, at least, to the
posterior surface of the remaining portion of
the hypogastrium. The cicatrisation once ef-
fected, the rest is explained by the mucous
nature of the organic septum, which occupies
the place of the pelvic or abdominal parietes. —
The umbilicus may or may not be implicated ©
in the loss of substance; the pubes, which are —
commonly destroyed, and not simply sepa-_
rated as has been believed, may be also pre- —
served ; and the vesical tumour may in some
cases only occupy a space of a few lines,
whilst in others it may implicate a great por- —
tion of the hypogastrium. — a
Those organs which are normally in relation
with the pubis present certain anomalies in —

“te 2 it i el

_ times even to adult age.

BLADDER, ABNORMAL ANATOMY. 393

extroversion of the bladder, which should be
mentioned in this place. The ureters, of
course, open immediately upon the surface of
the body; the urethra no longer serves for the
emission of urine, and is often incomplete.
Commonly in woman it opens above the cli-
toris, in man above the penis. Occasionally
the testicles do not descend. Meckel has
remarked that there is commonly a separation
of the two lateral moieties of the external
genital organs, like that of the abdominal
muscles and the pubis. It has been remarked
by Duncan (loc. cit.) that this infirmity more
commonly happens to the male than the female.
Meckel doubts this proposition, and adds many
cases to those cited by Duncan, in which the
disease affected the female. Isidore Geoffroy
St. Hilaire, who has carefully examined the
recorded cases, which are now very numerous,
supports the conclusion of Duncan: he says
that of these one-fourth appertain to females,

‘nearly two-thirds to males, and in the re-

mainder the sex was undetermined. Ex-
trophy of the bladder is a very serious af-
fliction, because of the incontinence of urine
which is its inevitable consequence, and the
deformity of the genital organs by which it is
constantly accompanied, and which, in man
especially, very commonly occasions impo-
tence. It constitutes a more serious disease in
the male than in the female, for in the latter
the external genital organs, except the want of
projection of the pubic eminence, commonly
suffer only slight modifications of form: the
ovaries, the uterus, and their appendages may
not even present any anomalies.*

Persistance of the urachus.—The last of
the congenital malformations to which I shall
allude is the persistance of the urachus some-
For a considerable
time much doubt was expressed whether the
urachus was ever a canal, pervious from the
bladder to the umbilicus ; and it was not gene-
tally admitted until the fact had been re-
peng demonstrated by Haller and his pupil

oreen. In January, 1787, Boyer exhibited
a bladder taken from a man aged thirty-six, in
which the urachus formed a canal an inch and
a half long, and containing twelve urinary
calculi, each of the size of a millet-seed; and
it was demonstrated that this canal was nota
vesical sac or a prolongation of the mucous
membrane. But these cases of persistance of
the cavity of the urachus in adult or even in
infant life are unquestionably extremely rare ;

* For more minute details of this affection the
reader may consult Blasius, part iv. obs. 6. Stal-
Vanderwiel, vol. ii. p. 56. Bartholin, cent.
li. hist. 65, the Edinburgh Essays, vol. iii. p. 257,
the Journal Encyclopedique, August, 1756, the
Journal de Médecine of Paris, t. v. p- 108, et t.
xxvii. p. 26, the Memoirs of the Academy of Sci-
ences of Paris, 1761, where we find an observation
of Lemery made in 1741, and three facts observed
by Tenon, also the second volume of Medical
ommentaries by a Society of medical men at
Edinburgh, p. 437, and the Memoirs of Duncan
(Edinb. Med, and Surg. Journ. 1805), and Velpeau
(Mem de l’Acad. Royale de Méd. tom. iii.)

and it is certain that a protrusion of the mu-
cous tunic in the form of a canal at this
point has been mistaken for the canal of the
urachus; it is even probable that generally
where the urine is prevented from escaping by
the urethra, and where it escapes by the umbi-
licus, it results from the rupture of the species of
hernia formed near the situation of the urachus
by the mucous tunic of the bladder, and not
from the dilatation of this membranous cord.

When this canal remains pervious only ina
part of its extent, the anomaly is not indicated
externally. When its cavity is preserved even
from the bladder to the umbilicus, nothing
marks its existence at the exterior if the urinary
passages are unobstructed; in the opposite
condition a very remarkable physiological ano-
maly accompanies it, and reveals the presence
of the anatomical anomaly; it is the total or
partial excretion of urine by the umbilicus,
either constantly and from the moment of
birth, which is the case when a vice of confor-
mation or a disease prevents the urine from
passing by its natural channel ;* or tempo-
rarily, when the course of the urine, which
was at first by the urethra, comes to be inter-
rupted by any cause.

Sigismund Konigt relates the case of a
woman in whom the urine, usually excreted
by the urethra, passed by the umbilicus during
some days in consequence of a severe labour ;
but this example and others which might be
mentioned do not appear to possess the authen-
ticity which is required to establish that this
infirmity may be acquired. It is probable
that many of these cases were simply a hernia
of the mucous membrane of the bladder, such
as occurred in the case detailed by Portal.}

ACQUIRED CHANGES.

Sacculi or cysts.—A sacculated or encysted
condition of the bladder is never a congenital
vice of conformation of that organ, but an
effect of disease. Sacculi may be produced
by any thing which can oppose itself to the
excretion of urine, or which may enfeeble the
muscular tunic of the organ. In this way the
urine becomes collected in the bladder, the
parietes are distended, the internal tunic is
forcibly applied upon the muscular coat, and
if at any point this tunic be weakened, less
resistance is offered, a separation between some
of its fasciculi takes place to a sufficient dis-
tance to admit of the mucous membrane pass-
ing between them, and in this way sacculi
may be formed.

This, however, is not the only way by which
this state may be produced ; in some bladders
the muscular tunic is so developed, probably
by irritation, that its fasciculi are grouped and
a columnar aspect is produced, not very unlike
to the appearance of the interior of the ven-
tricles of the heart.

* Littre, Mém. de l|’Acad. des Sciences, 1701, p.
23. Sabatier, Traité d’Anat. t. ii. p. 402, et t. ill.
p- 498.—Cabrol, Alphabet Anat. obs. 20. This
case occurred at Beaucaire in 1550.

+ Phil. Trans. v. 16.

t Mém. de l’Acad. des Sciences, 1769.

394

Certain portions of the parietes of the organ
are in such cases unprovided with the muscular
fibre necessary to enable them to offer the
usual resistance, and a similar effect is pro-
duced to that which I have already described,
the mechanism being somewhat different.

These sacs may attain great size, even supe-
rior to that of the bladder itself; commonly
the point by which communication with the
bladder is maintained is only a narrow neck,
and in consequence of this circumstance the
organ has occasionally been described as dou-
ble, triple, and so on. It is always easy to
determine whether it be really so or not, first,
by examining the parietes of each, and,
secondly, by ascertaining the points at which
the ureters are implanted. In the first case we
shall find only one of these compartments
invested by a muscular tunic; in the second
an ureter has never yet been known to pene-
trate directly the adventitious cavity.

There is scarcely any point of the surface of
the bladder in which such a state may not be
produced, but there are certain regions where
the affection is much more frequently met with
than others. They are most commonly formed
at the lateral parts, or at the summit, near
the insertion of the urachus. Occasionally
many of these sacculi are found in the same
bladder.*

A species of sacculi or appendices may,
however, be produced by an extension, at a
given point, of the whole of the vesical tunics ;
and even*these may be a consequence of re-
tention of urine, but more frequently of the
sojourn of a stone, which forms a cell.
Some examples of this species are given by
Morgagni.t A woman, two years before her
death, introduced into the urethra “ a long hair
pin ;” this instrument slipped from her grasp
and passed into the bladder, where it became
arranged transversely, so that whilst the point
rested upon the left, its head rested on the
right side of the organ. The head became
incrusted with calcareous matter; a stone of
the size of a nut was thus formed, which was
contained in a quadrilateral sac produced by
the extension of the whole of the tunics of the
bladder.

Cells or cysts may be otherwise formed at
the expense of the vesical parietes. Calculous
concretions may be formed in the kidney, and
may pass unobstructed through the ureter into
the bladder; but if the magnitude of the stone
be disproportioned to the capacity of the canal
of the ureter, it may sojourn at any point of the
continuity of this canal, or at the point where
it terminates in the bladder. If also the cal-
culous matter be abundant in the urine, it will
be deposited upon this nucleus, which will more
or less rapidly augment in volume, and will
be impacted at or near the point where it may
have acquired this augmentation. The first
author who speaks in a clear and precise man-
ner of this affection is the celebrated Pierre

* Heister.
+t De Sed. &e. ep. xlii. art. 18.

BLADDER, ABNORMAL ANATOMY.

Franco.* Since Franco, it has been des od by
by many others, particular] y by ‘Alexander MOE ee

rot and Houstet.t Theexistence of this affection _ ~*~

is certainly not frequent, but its occasional occur-

rence is amply proved: formed in the =

have described, these calculi occasionally glide _
between the mucous and muscular tunicsof the __
organ by means of an opening which they form
at the point where the ureter obliquely pierces
the bladder, instead of entering the bladder by
the natural channel. The volume of these cysts
is never very considerable, for such calculi do
not acquire anything like the volume of those
which are commonly found moving freely in the
cavity of the bladder. The reason of this is ob-
vious; they are not exposed to the action of any
considerable quantity of urine, and they cannot
consequently receive a large accession of calcu-
lous matter. Covillard§ and Garengeot|| have
seen them of the size of a hen’s egg, but such
cases are rare. Commonly they are very little
removed from the insertion of the ureters. The —
reason of this is not, however, that which was.
assumed by Littre,{{ because the contraction of
the muscular fibres is made towards the fundus,
and that in consequence the calculus would be
forced towards that region, but by reason of the
resistance offered by the membrane of the cyst
by which they are surrounded.
CHANGES OF CAPACITY.

The bladder may suffer certain modifications
of capacity as consequences of disease. It may
become so distended as to contain nie pounds
of urine (in puella pro hydropica habita,
Kenig)** novem chopines ab ischuria, La
Motte ;)++ or even twelve pounds, Felix Pascal:
or it may become so diminished that its volume
shall not exceed that of a small walnut. In
1764, M. Portal found at Montpellier, in the
dead body of a woman aged sixty, the bladder
so small that its volume did not exceed that of
a hazel-nut.

Decrease.—In persons who pass urine fre-
quently, the bladder is small; still more so in
those whose kidneys do not perform their fune-
tions properly. It is small in those cases of
irritation by which frequent contractions are
excited. Lithotomists have frequently remarked
that in calculous patients the bladder closely
embraced the stone. Morgagni, {{ in opening
the body of a girl of fourteen, found the bladder
adherent to the parietes of the abdomen imme-
diately above the pubis, and so contracted
around a needle, which had been introduced
sixteen months before her death, that this viscus
could scarcely have contained anything more.

* Traité des hernies, chap. xxxi. p. 107, Lyon,
1561.
+t Essays and Observations of the Medical So-
ciety of Edinburgh, vol. vi. p. 257. “a
ia Mém. de 1’Acad, des Sciences de Paris, ann.
02. » "9

Obs. 11.
ie de l’ Acad. de Chir., t. i. p. 411.
Mém. de ]’Acad. des Sciences, an 1702.
** Lith. spec. Epist. 11.
+t Traité des Accouchmens, Obs, 44. 5
tt De Sed. ep. xlii, art. 20. if

BLADDER, ABNORMAL ANATOMY.

The bladder is also very small in cases of
incontinence of urine and in vesical fistule,

Increase.-—The volume of the bladder aug-
ments when the whole or a great portion of
the urine is retained in its cavity, and under the
opposite conditions to those which have just
been named. To such an extent may this in-
crease proceed, that it may be mistaken for
ascites.* Inflammation of the bladder com-
monly accompanies its excessive dilatation,
but many circumstances related by Morgagni
and others prove that this viscus may be con-
siderably distended by urine without becoming
inflamed. It may, however, lose its contractile
power, and the assistance of art may be neces-
sary for the evacuation of the urine. A fact
stated by Mauchart+ shews that a man had
ischuria, which had commenced four days before
he was sounded. Some days after this he died;
the bladder was found inflamed in different
points. It was entirely empty and yet very
voluminous, without being contracted as it is
commonly after death.

Introversion—Among the acquired changes
of conformation of the urinary bladder, there
is one which may be termed introversion. In
this affection, which is rare, the superior por-
tion of the organ is so depressed as to be brought
near to its neck, to project into the urethra,
and in woman to make its appearance at the
external orifice of that canal. Chopart { relates
from Percy the following observation :—The
patient was an abbess aged fifty-two, in whom
the fundus of the bladder was impacted in the
neck, having also passed along the urethra,
and forming at its external orifice a tumour of
the volume of the eye of a pigeon, red, fleshy,
unequally tumefied, which, when pressed upon
with the finger, returned into the canal and
reappeared without any violent exertion. An
analogous case occurred to Foubert.§ The
patient died, the body was examined after
death, and it was found that the posterior and
Superior region of the bladder was depressed
into the form of a cone whose apex had pene-
trated the neck of the bladder, a portion of
ileum about six inches long being lodged in
this depression.

When, in the female, the summit of the
bladder is engaged in the neck, the simple
nes a of the tumour, its increase after
walking or in consequence of a fit of coughing,
its disappearance with compression, are sym-
ptoms sufficient to enable us to recognize the
disease. Those aged persons whose bladders
are very Capacious, and who are become feeble,
are most subject to this affection, which is
produced by the pressure which the other
viscera exercise on this organ.

Hernia.—The absence of information in old
authors on the subject of hernial displacement
of the urinary bladder induced an opinion
which was current for very many years, that the

* Chopart, Smellie, Black.

t Ephemerides Acad. Nat. Cur., cent. ix. obs. 41.

¢ Traité des Maladies des Voies Urinaires, t. i.
v. 399. Edit. 1830.

§ Mém, de l’Acad. de Chir., t. ii. p. 36.

395

affection we are about to consider was of ex-
tremely unfrequent occurrence. This, however,
is an erroneous opinion, for the experience of
modern times has demonstrated, that though
less frequent than hernia of the intestines or of
the epiploon, cystocele is not an unfrequent
disease.*

The inguinal ring, the crural arch, the peri-
neum, and the anterior walls of the vagina
may become the seat of a hernia of the blad-
der. At whichever of these points the disease
may be manifested, the bladder, fixed deep in
the pelvis and hidden behind the pubes, is
never completely displaced ; only prolongations
of the organ can pass these several points. It
must be at once evident that besides the dila-
tation of the opening through which it passes,
there must be a great increase in the capacity
of the organ itself, and a great relaxation of
its parietes, occasioned most commonly by
retention of urine, or by-a habit of only rarely
attending to a desire for its evacuation. Whe-
ther the protrusion occur at the one or the other
of the several regions I have named, there are
certain general characters by which it may be
more or less readily detected. We shall find
a soft tumour, accompanied by a fluctuation
which is as much more sensible, and which
acquires a volume as much more considerable
as the time which may have elapsed without
an evacuation of urine is greater. This tumour
may be easily lessened by compression, but
the reduction is immediately followed by an
urgent desire to pass the urine. +

This species of hernia is only partially co-
vered by peritoneum. Dominique Sala is,
according to Bartholin,+ the first person who
mentioned this peculiarity. The reason of this
circumstance is obvious: when the bladder is
distended, it is raised to the level of the crural
arch and of the inguinal ring; it pushes before
it the peritoneum, and insinuates.itself between
the peritoneum and the abdominal muscles.
If at this time a violent effort determine the
escape of the corresponding part of the organ
by one or other of these openings, it is the
anterior, superior, and. lateral part of the
organ which will be presented, and this is the
portion which is without a peritoneal invest-
ment; so that at this time the hernize we have
described are completely deprived of a sac.
It usually happens, however, that the posterior
portion of the organ soon follows, dragging
with it the peritoneum by which it is covered ;
this portion in turn drags down that which is
in the vicinity of the ring; and in this way a
hernial sac is formed, ready for the reception of
the intestine or the omentum. This is the
reason why a hernia of the bladder is so fre-
quently accompanied by an intestinal or omen-

tal hernia.

* For a confirmation of this opinion, see Blegny,
Traité des Hernies, 1688; Mery, Mém. de l’Acad,
des Sciences, 1713; Petit, méme ouvrage, 1717;
Le Dran, Garengeot, and La Faye. Heister and
Platner, Instit. Chir. J. G. Gunzii, Obs. an. Chir.
de Hernia, Lipsie, 1744; Monro, Levret, Sharp,
Pott, Scarpa, Lawrence, and others.

+ Hist, Anat., cent. xviii.

396

It does not appear to be well established
whether a primitive hernia of the bladder
occurs in the direction of the inguinal canal,
or whether it escapes directly through the
iponeurotic opening of the external abdominal
muscle, though the latter opinion is the most
probable. It has been remarked in some cases
that the spermatic vessels were external to the
hernia.

In consecutive vesical hernia an intestinal
hernia primarily exists; the intestine pushes
before it the peritoneum which surrounded the
ring, and in proportion as the hernia increases
in volume, does the sac augment, the peri-
toneum in the neighbourhood of the ring is
drawn down, and, as a consequence, that which
invests the posterior surface of the bladder, which
in its turn is also drawn down, if, on the one
hand, the adherence of the peritoneum to the
bladder be sufficiently strong, and if, on the
other, the latter organ be voluminous and sus-
ceptible of displacement. The primitive peri-
neal and vaginal hernie are similarly situated
as to the non-existence of a hernial sac, and of
the existence of consecutive hernia in these
situations we have no record.

The species of vesical hernia which is most
commonly seen is the inguinal; the tumour is
usually confined to the groin, but it may
descend into the scrotum, gliding along the
spermatic cord.*

Hernia of the bladder at the crural ring is
very rare. It presents the same characters and
is subject to the same complications as that
which occurs at the inguinal ring. Its form
and its seat only are different; it is developed
at the same pointas a merocele, and like it
takes a globular form.

Vesical hernia at the perineum is an ex-
tremely rare disease, and for some time was
supposed to occur exclusively in pregnant
women, but the observation of Pipelet is con-
clusive as to the possibility of its existence in
man. In these cases a portion of the bladder
passes between the fibres of the levator ani
muscle, and it is presented in the form of an
ovoid tumour placed at the side of the anus.
In each of the three species of hernia which
we have described, the bladder suffers certain
changes of form: it is contracted at the level of
the opening through which it passes, and is again
dilated below this point. This circumstance
has been observed by Keate, Pott, and Ber-
trandi. Sometimes even calculi have been
found in the displaced portion of the blad-
der.t

Few occasions have occurred of observing
hernia of the bladder through the vagina. In
this affection the fundus of the bladder de-
presses the anterior parietes of the vagina, and
forms a round projection, which is frequently
visible externally when it passes the level of

the orifice of the vulva. The disease is usually .

developed during pregnancy when pressure is
made by the distended uterus upon the neigh-
bouring organs; but cases have occurred at an

* Pott’s Surgical Works, vol. i. case 26.
+ Pott, loc. cit.

BLADDER, ABNORMAL ANATOMY.

advanced period of life. Of all the species of
hernia of the bladder, that by the vagina a :
sions the most pressing symptoms, and these
symptoms are principally owing to the devia-
tion which is produced in the canal of the —
urethra, which is drawn downwards and for-
ward by the fundus of the organ, so as to
prevent the passage of the urine along it. In _
this way a complete retention of urine is pro- __
duced, together with tension, pain and aug-
mentation of volume in the abdomen, agitation,
sleeplessness, sympathetic irritation of the
heart and the brain.

Considerable doubt has usually been ex-
pressed, whether hernia of the bladder is sus-
ceptible of true. strangulation; whether the
sensibility of this organ is of the same na-
ture as that of the intestines, and whether its
constriction might give rise to similar sym-
ptoms. In the case described by Plater,*
strangulation does, however, appear to hare
occurred, but the symptoms abich he detailed
were not well marked. The symptoms given
by J. L. Petit+ do not appear sufficient to
enable us to distinguish strangulation where
the bladder is implicated from that in which
the intestine suffers. Hiccup, says Petit, pre-
cedes vomiting in hernia of the bladder, while
in intestinal hernia the latter precedes the
former symptom. If strangulation should
occur, the method of relief proposed by Du-
rand, viz. to empty the tumour by puncture
with a trocar, appears rational.

Inflammation.—Inflammation of the blad-
der may be produced by a variety of causes:
among them we may mention external violence,
incised wounds of the organ, contusions on
the hypogastric or perineal region, concus-
sions of various kinds, the bladder being dis-
tended, the compression consequent upon
pregnancy, upon a laborious accouchement,
upon the use of the forceps, upon the pre-
sence of a pessary ora hernial displacement ;
the presence within the organ of foreign bodies,
whether introduced from without, generated
within, or derived from the kidneys, distention
consequent upon retention, and the use of
cantharides and certain other diuretic me-
dicines. It may also be communicated to the
bladder by neighbouring organs, such as the
kidneys, the urethra, the prostate, the uterus,
and the rectum. It may be developed during
the progress of acute gastro-enteritis, may
succeed to certain articular inflammations, to
certain cutaneous affections, and tothe sup-
pression of a hemorrhoidal or menstrual
flux.

The affection is more common in menthan _
in women, and at the approach of age than at —
any other period of life. Boisseau describes
the disease in a male child of two years old ;
Lesaive in a female child of two years and a —
half. Acute inflammation commonly affects —
at the same time more than one of the vesical _
tunics; there are, however, on record two cases —
in which acute inflammation was limited to

* Obs. lib. iii. p. 830. : - ae

+ Traité des Mal. Chir. tome ii. p. 368. ;

ee ee

BLADDER, ABNORMAL ANATOMY.

the peritoneal tunic of the organ.* Dr. Bail-
lie suggests, as a reason for such limitation to
this particular tunic, the quantity of cellular
tissue interposed between the serous and mus-
cular tunic, and the laxity of their connection
the one with the other. Chronic inflammation
is frequently confined solely to the mucous
tunic of the organ.

Acute cystitis may terminate by complete
resolution ; it may cause a secretion of pus,
which is either diffused in points over the
greater part or even the whole of the surface
of the organ, or circumscribed under the form
of abscess ; may produce ulceration, may ter-
minate in gangrene, or it may assume a chronic
form.

If death supervene during the intensity of
acute inflammation, we find the mucous mem-
brane strongly injected, patches being pre-
sented of a brownish colour, commonly in the
vicinity of the neck and fundus of the organ ;
nor does it appear that the occurrence of such
patches in these situations can be attributed to
the irritation occasioned by the prolonged con-
tact of acrid urine. At other times the mucous
membrane is thickened, and the veins much
dilated ; pus is disseminated over the surface,
or collected into foci; patches of false mem-
brane are extended over portions of the organ
or floating in the contained fluid, and gan-
grenous points are presented ; these points may
only affect the mucous tunic, or they may
affect the entire thickness; it is sometimes
studded with small ulcerations, which are more
or less concealed by folds of the membrane,
and not unfrequently it is softened. Usually
the organ is very much contracted, so much so
as to present only a very small cavity. This
effect is induced by the contraction of the
muscular fibres which is excited by the exten-
sion of the irritation from the mucous mem-
brane.

When the disease terminates by resolution,
ordinarily, in a short time, all trace of the
existence of the affection disappears. In cer-
tain cases, however, where it has existed long,
the parietes of the bladder have been found
slightly thickened; one or more branches of
veins have become varicose and consequently
more apparent. If the disease have had a still
longer existence, we may find the mucous
membrane thickened; but this effect is more
frequently manifested in the muscular tunic.

When a purulent secretion is produced, pus
is found diffused through the substance of the
parietes, more particularly, however, in the
cellular and muscular layers, and an appear-

-ance of hypertrophy is here produced ; or it is

poured out upon the surface of the mucous
tunic. Occasionally, but unfrequently, abscesses
are formed between the tunics, but these are
commonly a consequence of wounds or con-
tusions of this organ, or of the operation for
stone. In such cases the abscess may open
itself on the external surface of the bladder,
or upon the interior. Sometimes it is pre-

* See Baillie, Wardrop’s edition, vol. ii. p. 259,
and Nauche, Maladies des Voies Urinaires, p. 27.

397

sented upon the sides of the rectum, but
according to Chopart it is usually in the
neighbourhood of the neck of the organ that
suppuration commences. When an abscess
opens upon the internal surface of the bladder,
the pus passes out, mixed with the urine ; in
such cases we discover after death more or less
extensive and profound fistulous openings,
which are sometimes surrounded by varicose
veins, sometimes covered by dark grumous
blood, exfravasated from the small vessels
which ramify on them: they all exhale a
fetid odour.

Ulceration of the bladder as a consequence
of acute inflammation is unfrequent ; indeed,
of this affection there are only a very small
number of cases on record. When it occurs,
it is commonly caused by the opening of a
purulent collection upon the mucous surface
of the organ. A case, detailed by Marechal
in the 28th vol. of the Recueil Périodique des
Travaux de la Société de Médecine de Paris,
is the best marked case of the affection with
which we are acquainted. It was that of a
hussar, in whom the affection appeared to be
brought about by a violent attack of gonor-
rhea: the patient died on the fifth day. Upon
an examination of the organ after death, it was
found rather contracted; though not filled
with urine, its parietes sustained themselves ;
it contained eight ounces of a greyish thick
matter: the mucous membrane was extremely
thick, and covered by a glutinous stratum.
It presented, however, many ulcerations of
varied extent; the parietes of the organ were
six lines in thickness.

Occasionally it happens that inflammation
of the mucous membrane of the bladder pro-
ceeds to gangrene, which is characterised by a
change in the volume of the hypogastric tu-
mour, supposing the organ to be distended,
the cessation of pain, the sudden prostration
of the vital powers, the complete suppression
of the flow of urine, the excessive distention
of the bladder and the ureters, and sometimes
by the escape of urine by the umbilicus ;*
more frequently, however, by the rupture of
the organ and the-extravasation of its contents
into the abdominal or pelvic cavity. In cases
which are a consequence of retention, the gan-
grenous points may be presented either at the
fundus or at the summit of the organ ;+ but
most commonly the affection is a consequence
of the irritation or pressure made upon the
bladder by a foreign body, and in these the
point implicated is that upon which the body
has directly exercised its influence. When
we examine the mucous surface of an organ
so affected, we discover that the disease exists
under two distinct forms, the diffuse and the
circumscribed ; but the latter of the two forms
is not often witnessed except as a consequence
of local violence. Dr. Carswell, however, bears
testimony to its occasional existence ; he states
that the congestion is extreme, and often ac-
companied by hemorrhage, which gives to the

* Walther, loc. cit.
+ See Hunter, Hey, and others.

398

membrane a uniform deep red colour. More-
over, dark brown or black patches are found
to occupy portions of various extent of the
mucous membrane, which, as well as the
submucous tissue, is easily torn, and other

rtions of this membrane are seen partially

etached, and converted into a soft spongy

substance having a strong gangrenous odour.
In the circumscribed form of gangrene, we
sometimes see a number of black eschars,
which are soft and nearly putrid : sometimes
greyish pulpy points are presented, which
appear to implicate only the mucous tunic,
but in the greater number of cases we see the
different stages of their progress; they are at
first whitish, they then become yellowish, grey,
slate colour or brown, and blackish ; but these
changes are much more marked when the organ
has been subjected for a short time to the
action of the atmosphere. Where the whole
of the parietes are involved, the eschar is
characterised by a greyish slaty tint. These
eschars are frequently confounded with the
violet or brown portions or patches by which
they are surrounded ; these latter are simply
extreme congestion, bordering, it is true, upon
gangrene, but susceptible of being restored to
a healthy state, whilst the death of the other
points is inevitable.

When acute inflammation affects the mus-
cular tunic of the bladder, the organ usually
becomes strongly contracted, and the parietes
present an appearance of considerable thicken-
Ing; at the same time pus is commonly in-
filtrated through the tissue, or it is circum-
scribed into the form of abscess; the tunic is
then of a dark red colour and strongly in-
jected. In acase which was seen by Gendrin,
where the patient refused to submit to the
operation for stone, the internal tunic was
ulcerated and of a red-brown colour; the mus-
cular tunic was more than half an inch in
thickness, and contained two abscesses, each
of the size of a small nut. Velpeau saw ina
patient who had died of a diarrhea, the blad-
der reduced to the size of a small fist; it was
hard and elastic; its parietes were more than
an inch thick. In the cases described by
Martin Ripaux, Molat, Maret, and Berard,*
the mucous membrane was not in any way
implicated, the hypertrophy being entirely
limited to the muscular tunic. In these cases
the bladder was reduced to very small dimen-
sions, and the mucous coat made many pro-
jections into the cavity; the summit of these
projections was red and vascular. It is not
unlikely but that it may be owing to the excess
of extent of the mucous over the contracted
muscular tissue in such cases, that the former
so easily becomes engaged in the formation of
appendices. The muscular tunic may be
much increased in thickness in the absence of
acute or even chronic inflammation of the
organ ; any irritation by which a frequent con-
traction of the organ may be excited will most
probably produce a great increase of thickness
of this tunic. Among these causes we may

* Vide Transact. de la Société Anatomique.

BLADDER, ABNORMAL ANATOMY,

range the existence of fistula or calculi in the
organ. Sometimes the thickening is limited
to the mucous tunic.
the bladder of an old man, the parietes of the
organ being eight or nine lines in thickness,
found the internal tunic like cartilage, and
that this was the only tunic which had acquired

an increase of substance; the peritoneal tunic

was in its natural state, the muscular scarcely
apparent. Chopart made a similar remark
with regard to the bladder of an adult. Mor-
gagni meutions a like case.*

Instead of either of the modifications which
have been described, acute cystitis may dege-
nerate into a chronic form of the disease.
This form of the affection does not commonly
succeed toa single and simple attack of the
acute affection ; almost always there will have
been sundry recurrences of the acute form
before this degeneration takes place. Most
frequently chronic cystitis occurs without hav-
ing the acute disease as a precursor, and it is
upon chronic inflammation that extensive dis-
organisations of the various tissues of the eco-
nomy are mainly dependent; and the altera-
tions of texture in the parietes of the bladder
are, therefore, most commonly produced by its
agency.

In such cases we may see the mucous mem-
brane of an uniformly dark violet colour, thick-
ened and unyielding, the organ so contracted
as to present only a very small undilatable
cavity, incapable of containing more than a
few drams of fluid. Fungous excrescences
are sometimes developed upon its internal
surface, especially in the vicinity of the neck.
In some cases ulcerations will be found to
have destroyed the muscular tunic and pene-
trated to the peritoneum; in others, the
mucous follicles present a most exaggerated
development, communicating to the membrane
a considerable increase of thickness, but with-
out change of colour. In other cases, the
muscular tunic having acted with increased
energy, its fibres have become more volumi-
nous and project into the interior of the
organ in the form of columns, between which
the mucous membrane sometimes forms what
is termed ‘ hernia.’ But the more ordinary
consequence of chronic inflammation of this
organ consists in the thickening and more or
less uniform induration of the vesical pa-
rietes. The tissue of the bladder is then con-
verted into a homogeneous, lardaceous sub-
stance, similar in appearance to that of the un-
impregnated uterus; the vessels which surround
the organ are dilated, varicose, and form on
the external surface considerable plexuses,
which attest the long existence of its excitation,
and the continuance of the afflux of blood of
which it has been the seat.

Ulceration as a consequence of chronic in-
flammation of the mucous membrane of this
organ is unfrequent, but as an effect of the —
presence of a calculus is less so.

by Baillie, of a case in which the mucous ~

* Ep. 41, art. 6.

M. Portal, in examining

Of the first —
species a description, with a fine plate, is given

a ‘

BLADDER, ABNORMAL ANATOMY.

membane covering the posterior and superior
surface of the bladder was destroyed ; a simi-
lar case is given also, with a plate, by Walter ;
another is described by Paré.* A case is
described by Jalon,t in which the whole of
the muscular tunic was as well displayed as if it
had been prepared by dissection. There are
several well-marked cases on record in which
this species of ulceration, consequent upon
chronic inflammation, had extended to the
whole of the tunics and caused an extrava-
sation of urine. These ulcerations are some-
times very numerous, almost like erosions, and
they are often concealed between the folds
of the relaxed mucous membrane, so that they
are not discovered until the membrane is
stretched out. Under the influence of either
acute or chronic inflammation, pseudo-mem-
branes are now and then generated upon the
surface of the mucous tunic of the organ,
usually during the suppurating period of the
affection. These membranes are either ad-
herent or free, and they are sometimes ex-
pew through the urethra: this circumstance
as induced a belief in an often repeated error,
that the mucous tunic of the bladder may be
entirely detached and expelled with the urine;
among those who have perpetuated this error
are Ruysch and Morgagni.}

Under the influence of chronic, and much
more rarely of subacute inflammation, the
mucous membrane of the bladder furnishes in
large quantity a species of muco-purulent
fluid. ‘This affection was termed by Lieu-
taud § catarrh of the bladder. When the
affection presents the subacute form, it is fre-
quently extended to the other tunics of the
organ; and if we examine it after death, we
shall find similar appearances to those which
have been Aésinibes in speaking of acute in-
flammation. When the disease is chronic, it
often lasts for years, and we then discover
little change of colour in the membrane, but
we find it often prodigiously thickened, the
vessels varicose, and the cavity much con-
tracted.

Idiopathic softening —During the progress

of some acute and many chronic diseases, :

the mucous membranes of the body not un-
frequently become softened, in the absence
of inflammatory action in their tissues: in the
bladder, however, this state has been only very
rarely witnessed. ‘This fact is important, espe-
cially when we reflect upon the functions of
the organ and the great variations to which the
ae of which it is the reservoir is exposed.

- Louis,|| in a very careful examination of
five hundred bodies, found this idiopathic
softening in only two cases. In these the
mucous membrane in a great portion of the

* Lib. xvii. ch. 59,

t Eph. Nat. Cur. D. 11. an 11. obs. 129.

¢ A case of the kind is detailed by M. Destrées
in a Journal Général de Médecine, tome Ixviii.
p. 206.

§ Méd. Prat. tom. i.

Il Repertoire Général, tome iv. part i. Faits
relatifs aux lésions de la membrane muqueuse de
la vessie.

399

fundus of the organ was reduced imto a
“ mucilage” possessing a consistence little if -
at all superior to that of mucous pseudo-mem-
branes. The membrane thus altered was pale,
even at the limits of the softening ; there was
no injection or vascular congestion at any point
of the bladder, nor in any of the vessels which
existed on the exterior of the organ; neither
was there at the interior any erosion or other
product of inflammation. It is probable that
it is in such cases that even a careful intro-
duction of the sound has occasioned a per-
foration of the bladder; it may be as well to
mention that no true friability of the mucous
membrane, so commonly found in inflam-
mation, existed in these two cases; the tunic
was soft, as if formed of a viscid jelly, but it
did not present either the redness, the infil-
tration or the induration by which inflam-
mation is characterised. So general is the
opinion that softening is uniformly a conse-
quence of inflammation, that in taking an
Opposite opinion it appears to be incum-
bent upon us to state our reasons for doing
so. Although the differences which may be
remarked between softening of this tissue
and its inflammatory condition appear to be
very great, yet able observers have still be-
lieved themselves justified in regarding all
softening as the result of inflammation. It is
so important to have correct ideas on this

oint, that we ought here to refute the reason-
ing by which that opinion is supported. It is
stated that softening of mucous tunics is, in
the greater number of cases, united to evi-
dently inflammatory alterations; such as a
more or less vivid redness of the softened
parts, together with an injection and tume-
faction. This assertion is gratuitous; for in
all cases where the condition has been well
observed, softening in the first degree has
scarcely ever been united to unequivocal in-
flammatory alterations. In the second degree
of softening, the existence of inflammation is
frequently demonstrable.

It is especially by studying the anatomical
characters of the early stage of softening
that we shall be enabled to establish the
non-existence of inflammation; we may go
farther, and say that the characteristics of sof-
tening are directly opposed to those of in-
flammation. In the latter we find injection
and vascular congestion; in the former the
capillaries have disappeared ;—in inflammation,
thickening, and at first augmentation of density
in the membrane, which becomes rugous to
the touch; in softening we find thinning and
diminution in the density of the tunic, with
loss of its tenacity, and it is soft to the touch ;
—in inflammation we observe specific inflam-
matory products at the surface and in the sub-
stance of the tissue; in softening a diminu-
tion and absence, then a total extinction of this
secretion, which is not only not augmented at
the commencement of the disease, as in the
first stage of inflammation, but is immediately
diminished.

Inflamed tissues at a certain epoch do, it is
said, become soft and friable; why should it

400

not be so in mucous or villous tissues ?
Although this reasoning proves nothing,—for
we cannot judge from analogy in a graphic
science like pathological anatomy,—yet it is
the simple expression of the truth, because it
is certain that mucous tunics are softened by
inflammation, but this softening does not re-
semble in any thing the idiopathic softening.

Rupture.— Rupture of the bladder is a
more frequent occurrence than that of the
cesophagus, the stomach, or the intestines ; it
occurs sometimes without external violence,
simply by a distention of the organ, from a
prolonged retention of urine; most commonly,
however, it is produced by a violent blow, or
the passage of the wheel of a carriage over the
hypogastrium, or the violent efforts to which
a woman is subject during the pains of labour,
the bladder being in a state of plenitude. In
the first case, the rupture usually occurs near
the insertion of the ureters or the neck of the
bladder, because it is at these points that the
distended organ usually begins to thin and tear.
In the second case it is usually at the inferior
fundus of the organ that the rupture is found.

We have already pointed out the circum-
stances under the influence of which the blad-
der may be ruptured, and we have stated that
the extravasation of urine by which it is fol-
lowed is commonly productive of fatal con-
sequences.

In a certain but small number of cases,
the patient is able to resist the inflammatory
symptoms which are developed, urinary ab-
scesses are formed, which may open either in
the vicinity of the umbilicus, at the hypo-
gastrium, in the inguinal region, in the vagina,
at the perineum, or in the rectum, and a fistu-
lous canal is organised.

Fistule. — Fistulous communications. be-
tween the bladder and the vagina or in-
testines are commonly the result of purely
mechanical causes, such as the action of a
calculus which may destroy the recto-vesical
septum, the action of a foreign body introduced
into the anus and penetrating the bladder,
the lateralised or recto-vesical operation for
stone, the operation of lithotrity, or as a con-
sequence of the pressure produced by the
head of the child in parturition. Vesico-in-
testinal fistule sometimes establish a com-
munication between the bladder and the ileum
or colon,* and then the summit of the bladder
is usually the seat of injury. When the com-
munication is established between the bladder
and the rectum, the posterior surface of the
bladder is commonly implicated; the neck of
the bladder may, however, be similarly affected,
and then it is commonly owing to the action
of a calculus or other foreign body directed
upon this portion of the vesical parietes. At
other times the lesion succeeds to chronic in-
flammation, or to a cancerous ulcer which has
extended from the rectum to the bladder; and
then the perforation almost always exists near
the neck of the latter. The communication of

* London Med. Journal for 1784, part 2; Edin-
burgh Medical Commentaries, vol. ii, part 2,

BLADDER, ABNORMAL ANATOMY.

the intestine with the bladder is sométimes
established without abscess, without external
inflammation. Sometimes the urine does not
escape by the rectum, while fecal matter and
flatus pass from the rectum into the bladder. —
Ordinarily, however, the urine passes into
the rectum and often causes diarrhea; the
bladder, distended by intestinal gas, forms a __
sonorous and painful tumour at the hypo-
gastrium. :
Vesico-vaginal fistule are sometimes though
rarely occasioned by the action of a foreign —
body introduced into the vagina; sometimes
they are the result of the progress of a uterine
cancer; but in general the cause by which
they are produced is a laborious accouchement,
during which the head of the infant has re-
mained long in the passage, and has by its
pressure determined gangrene of the vesico~
vaginal septum. The accident may be pro- :
duced by the imprudent use of instruments ;
but this is a rare occurrence, perhaps for the
reason that instruments are comparatively un-
frequently employed. _in a few days the
eschars which are the result of that gangrene
are thrown off, and the consequent loss of sub-
stance may then be demonstrated. We find
that these fistule have not always the same
form, the same direction, nor the same extent.
In some cases they are longitudinal, at other
times transverse; in others their form is irre-
gular. The extent of the loss of substance is
also very variable: sometimes the fundus of
the bladder is extensively destroyed, so much
so as to allow of the opposite parietes of the
organ being implicated in the opening, and
forming a true vesico-vaginal hernia. When the
disease is a vesico-umbilical fistula, the com-
munication is with the summit of the bladder,
and is commonly caused by a dilatation of the
urachus or by the prolongation of the mucous
membrane of the bladder, which is directed
along the cord produced by the conversion of
the urachus and the vessels by which it is
accompanied into a cellular structure.* In
either case the disease is almost invariably a
consequence of the existence of some ob-
stacle to the passage of urine along the
urethra.
The pubic and inguinal fistule succeed to
an accidental opening of the bladder, which,
having formed a tumour in those regions,
has been taken for an abscess, a hernia, or an
encysted tumour; to wounds, to ruptures,
puncture, or incision of the organ; to its per-
foration in consequence of a purulent focus
being in contact with its parietes, or by a suppu-
ration in these parietes themselves. All fistulae
of the bladder have this in common, that the
urine escapes from their orifice drop by drop, -
almost continually, often without contraction —
of the bladder, and without the patient having
wished to urine; sometimes it escapes in —
greater quantity during those motions of the —
body which excite the pressure of the abdo- —
minal muscles. In consequence of the hab
which the bladder has acquired of remaining

) ot
re

* See Van-der-Wiel, Littre, Tenon, and Roux. —

—E———— ee

— OO ee ee,

by “8
cme |

——————<—

+
r
yo
e
i<

BLADDER, ABNORMAL ANATOMY.

empty, it almost always becomes contracted ;
in all cases its capacity is considerably di-
minished.

Hemorrhage from the bladder—Instead of
the mucus which is furnished by the mucous
membrane of the bladder when in the state of
health, it may be the seat of a sanguineous
exhalation. When a sanguineous fluid is
excreted from the bladder, it does not of neces-
sity follow that it has proceeded from the
mucous membrane of that organ; it may be
brought by the ureters from the kidneys.
When the fluid is produced within the vesical
cavity, the mode of production is not uniform :
it may be a simple exhalation from the mu-
cous membrane, or it may be a consequence
of the destruction of the mucous membrane
by gravel, by a calculus, or by a foreign body
introduced from without; or it may be a con-
sequence of the rupture of varicosed vessels.
Blood is, however, rarely exhaled at the in-
ternal surface of the bladder, unless the mu-
cous membrane be in a state of structural
disease: yet this exhalation is occasionally
manifested as a result of intemperance, or the
use of certain irritating diuretic medicines,
concussions of the pelvis; in woman the sud-
den suppression of the menstrual evacuations,
and in man of a hemorrhoidal discharge.

It is very difficult, and sometimes even al-
most impossible to determine whether the
fluid be derived from the kidney or from the
bladder; and to arrive at any thing like a sound
Opinion, it is necessary to consider carefully all
the circumstances of the case. Much as it has
been relied on, we cannot consider as a sym-
ptom peculiar to vesical hemorrhage, the mix-
ture of blood with the urine, and the sensation
of burning and weight behind the pubis, at the

rineum, and at the extremity of the penis;

r these symptoms occur in some cases where
there is no effusion of blood, and in others
where the blood has arrived from the kidneys.

It is also very difficult to decide as to what
is the exact state of the bladder, even when
we are convinced that the blood discharged
from the urethra is derived from that organ.
Chopart found the vesical mucous membrane,

More particularly at the fundus, studded with

red points in an old man subject to hematuria ;
these points appeared to him to be vascular
orifices.* In other persons who have suffered
from a similar affection, different kinds of

_ fungus have been discovered on this mem-

brane. A man, aged seventy-three, had hama-

_ turia, but there was no stone in the bladder.

As there was no appearance of disease about
the kidneys, it was attributed to the rupture of
Some varicose vessels in the neighbourhood
of the neck of the organ. After death the

__ bladder was found of great size, and within the

trigone was a fungous rounded ulceration, six

_ lines in diameter, surrounded with varicose
_ veins and small fungous excrescences. Ordi-

narily, however, gravel or calculi appear to be

_ the exciting causes of this disease.

* Loc. cit. tome ii. p. 52,
VOL. I.

401

Fungous tumours.—The information which
we possess on the subject of fungous tumours
or excrescences of the bladder is not sufficiently
precise to enable us to attempt to arrange
them according to their variety in structure or
development. The tumours which we pro-
pose to describe are those which do not im-
plicate the whole of the parietes of the organ,
but project into its cavity under the form of
more or less perfectly pediculated excrescences.
We are, therefore, under the necessity of con-
sidering simultaneously all those tumours,
however variable in structure, which come
under the definition which we have given.
Many eminent pathologists have expressed an
opinion that these tumours are always directly
connected with the prostate; but their occa-
sional existence in the female sufficiently
proves that this opinion is incorrect. In 1750
Mr. Warner removed from the bladder of a
woman a fungous tumour of the shape and
size of a turkey’s egg. Walter* details the
case of a young woman in whose bladder he
discovered what he calls a polypus, which ex-
tended itself nearly to the external orifice of the
urethra. It is true that these morbid products are
more commonly seen at the fundus of the blad-
der than at any other point of its surface, and it
is equally true that a large number of those
affections which are described as fungous tu-
mours of the bladder, were really morbid
products arising from the prostate, which will
be described in the article on the Prostate
Guanp.

The circumstances necessary for the develop-
ment of these tumours are unknown, but it would
appear that the larger number occur under the
influence of irritation produced by calculus.
Ordinarily only one of these tumours is found,
and then occasionally it attains a considerable
volume. Fabricius Hildanust describes one
of the size of a hen’s egg, and weighing two
ounces. Zacutus Lusitanus{ found one of
these polypi of the size of a goose’s egg, and
so hard that he could not cut it with scissars.
There are, however, many examples in which
a greater number existed, but in these cases
the tumours are usually small. Chopart§ de-
scribes a case which he examined at the Hotel
Dieu, in which there were found three tumours,
the largest being nearly as large as a cherry.
Ludwig describes a case in which he found
two of small size in the bladder of a man of
sixty-three. Desault once saw the whole of
the cavity of the bladder studded with small
“ fungous tubercles.” Lobstein|| has seen
three, and Bartholin§ two. This affection is
rarely seen before adult age. Morgagni** has
never seen them in infants or in young persons.

* Einige Krankheiten d. Nieren und Harnblase,
4to. Berlin, 1800, tab. iii.

+ Cent. ii. obs. 65.
t Prax. Med. Ader. lib. ii. obs. 71.
’ Loc. cit. tome ii, p. 77.
| Dis. de Dysuria.

Anat. cent. ii. Hist. 52. p. 243.
** De Sed. ep. Ixvi. art. 12.

2D

402

Deschamps, in 1791, whilst removing a cal-
culus from’ the bladder of a boy of twelve
years, discovered; on the anterior and lateral
parietes of this organ, a small fungous tumour
of the size of a cherry, which projected to the
distance of half an inch from the surface.
Baiilie, in his Morbid Anatomy, has given a
plate of a polypus of the bladder which he
found in a child, and which not only occupied
the whole of the cavity of the organ, but sent
prolongations into the urethra.

The structure of these tumours is very va-
rious ; the greater number appear to possess a
fibrous structure, others present a white homo-
geneous, lardaceous texture at their base, whilst
their free surface may be red, vascular, or even
carcinomatous; sometimes they are hard and
almost cartilaginous in their whole thickness ;
at others they present calcareous concretions.

Around the points from which these tumours
arise the bladder is ordinarily thickened and
indurated : this is, we apprehend, a consequence
of the continued irritation which has attended
their development.

Varices. — The arteries and veins of ‘the
bladder present numerous ramifications in
the cellular stratum, which separates the
muscular from the mucous tunic of this
organ ; and in the neighbourhood of its neck
they form an immediately apparent plexus.
This vascular structure in inflammation be-
comes so marked that the mucous membrane
appears to be entirely formed of these vessels.
Though it might be expected that during the
existence of inflammation these vessels would
become more dilated and manifest, yet it
cannot be regarded as atrue varicose condi-
tion, there being neither partial dilatations
nor projecting indurations like those which
characterize varices situated in other parts of
the body. Bonnet describes the case of a
man, who during life had suffered from the
ordinary symptoms of stone, but in whose
bladder no stone was discovered after death.
The veins around the neck of the bladder
were varicose and very much distended
with blood.* Morgagni discovered in the
body of a man aged sixty, in which the
tunics of the bladder were very thick, large
vessels creeping along its internal surface
around its neck. They were so distended with
blood, that at first he almost believed they
were hemorrhoids rather than parallel vessels.+
A similar case is described by Chopart, in a
calculous patient. There cannot, therefore,
be any doubt that sucha disease may exist.
It appears to occur principally when the
parietes of the bladder are thickened, when it
contains calculi or fungi, or when its neck or
the prostate are tumefied. It is not unfrequent
in old men and in inhabitants of warm
countries. The disease has much analogy
with hemorrhoids, and appears to increase
under similar sources of irritation. It may
contract the neck of the bladder and so cause

* Sepul. lib. iii. sect. 25, p. 263.
+ De Sed. ep. 63 art. 13.

i,

BLADDER, ABNORMAL ANATOMY.

retention, These veins may become inflamed
and produce divers alterations in the mucous
tissue. This membrane may be thinned, take
a fungous appearance, give rise to hemor-
rhage, in fact assume somewhat of an erectile
character.

Scirrhus and Cancer.—Cancer primitively
affecting the membranes of the bladder is an
extremely rare disease. Chopart relates only
one example of the kind.* Desault describes
another; Lallemand another.{ Soemmering
appears to doubt whether the disease ever
exists. In each case to which I have alluded
the disease occurred in man, and I know of
no case on record in which the disease has
primarily existed in the bladder in woman.
In the whole of the cases the disease was
characterized by lancinating pains behind the
pubis, and by the emission of particles of de-
composed animal matter ; these were the only
symptoms which were calculated to excite
suspicion as to the nature of the disease. In
every one of them the scirrhus was situated in
the fundus of the bladder and near its neck.
The whole of the membranes at that point
were transformed into a scirrhous lardaceous
substance, varying in thickness from two to
four inches, and in two cases the tumours were
somewhat funnel-shaped, the internal surface
of which was unequal, bristling with very
projecting vegetations of a cauliflower cha-
racter. Most commonly the affection is the
result of the extension of a similar disease
from the uterus or the rectum, and the symp-
toms by which the affection might be announced
are confounded with those of the affection of
the uterus or of the rectum. This affection
may exist with dilatation or centraction of the
cavity of the organ, with or without ulceration,
with or without hypertrophy of the muscular ~
tunic. When derived from the uterus, the —
affection is manifested at the fundus of the —
organ, and a communication is usually soon
brought about between it and the vagina, and
as a consequence the urine flows involuntarily
from the vulva. When derived from’the rec-
tum, the fundus is commonly affected ; and in
either case these productions are manifested
within the vesical cavity under the form of
fungous vegetations.

Paralysis.—The bladder is not an excep-
tion to the rule, that “ all parts of the body
may become unfit for the functions which they —
are destined to perform ;” it may lose the fa-
culty of contractility, which is indispensable to
the accomplishment of excretion. Under many —
circumstances it may contract with too much
force; ina still greater number its contracti-
lity is enfeebled and ultimately destroyed.
Apoplexy, hemiplegia, paraplegia, concussion,

if

* Traité des Maladies des voies urinaires, tome i.
p- 466, Edit. de 1821. “Theg
‘ # sc des Maladies des voies urinaires, 3d edit.
p- e
¢{ Obs. sur les maladies des organes ge
urinaires, p. 8. us
_§ Traité des Mal. de la vessic et de l’urétre, trad.
de H. Hollard, 1824.

i-

BLADDER, ABNORMAL ANATOMY.

and inflammation of the brain and its meninges,
extravasations within the cranium, and still
more concussion and inflammation of the spinal
marrow and its membranes, and extrayasations
within the spinal canal, consequences of con-
tusions of this part; the excessive distention of
the bladder by the accumulation of urine
within its cavity, either in consequence of
neglecting to attend to the desire of excretion,
or because the want has been resisted by false
delicacy, or because an obstacle exists at the
neck of the bladder or in the urethra; inflam-

mation of the mucous membrane, especially.

when it affects the neighbourhood of the neck
of the organ ; the sudden cessation of articular
pains, inflammations of the skin or of the
sata organs ; exasperated gastro-enteritic af-
ections which are accompanied by affections

_of the brain and the spinal marrow ; abuse of

the sexual organs ;—these are among the cir-
cumstances under the influence of which the
bladder loses partially or completely its con-
tractility.

We must not therefore regard all cases of
paralysis of the bladder as evidence of feeble-
ness, nor confound the inability to contract,
with those mechanical obstacles which, acting
on the bladder or the urethra, oppose the ex-
cretion of urme. We should always endeavour
to ascertain whether there be a real paralysis of
the bladder in cases where the brain or the
spinal marrow is injured, and where there is

etected abuse of the sexual organs. When
retention is primitively the effect of inattention
to the desire to pass urine, there is only exces-
Sive distention of the muscular fibres, but that
distention is formidable in its effects; for no
fact is better established than this, that when
we submit muscular fibre to excessive distention
or contusion, it loses the faculty of contracting.
Again, in cases of inflammation of the bladder,
there is less of paralysis than a suspension of
contraction in the muscular tunic, in conse-
quence of the proximity of the mucous tunic,
which by reason of its inflammatory state be-
comes still more painful when its tissue is

_tufiled by contraction. There may, however,

De atony or even a real paralysis of the mus-
cular tunic during the existence of inflammation
of the mucous tissue.

It is important to distinguish the case where
paralysis is simple from those in which it is
complicated by inflammation of the mucous
membrane of bladder or that of any other
organ, and for that purpose it is necessary to
analyse with care the symptoms. We must
also bear in mind that from simple, complete,
and primitive paralysis of the muscular tunic
to inflammation of its mucous tunic, the inter-
val is only very short, in consequence of the
irritating impression which is exercised by the
accumulated urine which has become much
deteriorated in its qualities by its prolonged
retention. From the time when paralysis is
fairly established, the bladder is quite insensi-
ble to the stimulus of the urine—it is merely
an inorganic sac, which may become enor-
mously distended. Haller found in a drunkard

403

the bladder so dilated that it was capable of
containing twenty pounds of water.* Frank+
saw a similar bladder which simulated ascites;
he evacuated from it at one time twelve pounds
of urine without removing all that it contained.
William Hunter, in his Anatomy of the
Gravid Uterus, plate 26, has given a fine repre-
sentation of a bladder which extended as far
as the xiphoid cartilage of the sternum.

This affection may, according to Baillie,f
exist during two distinct states, one when the
muscular tunic of the bladder has lost its
contractile power, the other while that power
is still retained. He adds, that after death
these two cases cannot be distinguished the
one from the other, but that by an attentive
examination of the symptoms the existence of
each may be recognised during life. It may
be complicated with inflammation of the organ,
and in this case rupture of the bladder may
occur,§ to which may be added the case of
the celebrated Tycho Brahe.|| Zuber { dis-
tinguishes this affection into that of the neck
and that of the body, and this distinction is
important, for the second being sometimes
accompanied by a species of spasm or want of
consent in the neck, a retention of urine must
be the result, whilst the former occasions
incontinence of that fluid.

Spasm.—Spasm of the bladder is an affec-
tion of frequent occurrence ; it accompanies the
various forms of cystitis, calculus, and often in-
flammation of the urethra. In fact it may be ex-
cited by any kind of irritation of the bladder or
urethra, or by certain affections of the kidneys
and of the rectum. It is not our purpose to con-
sider in this place any other than what may be
termed the idiopathic species of this affection.
Hoffmann describes the case of a man who
sank under the numerous and violent attacks
of this disease, and in whom, after death,
except in one particular, the bladder was found
perfectly healthy; this was in the thickening
and dilatation of its vessels, in which there
was still much blood. Of course, although no
anatomical lesion was found in this case, some
irritation capable of exciting the spasm must
have existed.

BIBLIOGRAPHY.— Rutty, A treatise on the urinary
passages, &c. 4to. Lond. 1726. Zuber, Diss. de
vesice urinarie morbis, 4to. Argent. 1771. Adams
on stone and gravel, diseases of the bladder, &c.
8vo. Lond. 1772. Lentin, Krankheiten der Harn-
blase der Alten, in Ej. Beytrage iii. Bd. 1780.
Troja, Mali della vesica orinaria, 2 vol. 8vo. Nap.
1785-88. Frank, J. P. Orat. de vesica urinaria
ex vicinia morbosa zgrotante, 8vo. Ticin, 1786, in
Ej. opusc. No. 4, Malacarne, Osserv. anat. e
pathol. sugli organi uropoetici, in Mem. della Soc.
Ital. vol. iii. et vol. v. 1780. Chopart, Des ma-

* Elementa Physiologie, art. Vesica.

¢ Oratio de signis morborum ex corporis situ,
partiumque positione patendis, Ticini, 1788.

¢t Path. Anat. chap. xiii.

§ See cases related by Ploucquet, Bibl. Med.
Pract. ‘ ;

|| Petri Gassendi Tychonis Brahei vita, Paris,
1654, in 4to. p. 206.

4] Diss. de Morbis vesice.

2D 2

404

ladies des voies urinaires, 8vo. Paris, 1791. Mac-
beath on affections of the urinary organs among ne-
groes. in Edinb. Med. Comment. Dec. 2, vol. x. 1798.
Desault, Des maladies des voies urinaires (4 Bichat
Ed.) 8vo. Paris, 1799. Sherwen on diseased and
contracted urinary bladder, 8vo. Lond.1799. Walter,
Einige Krankheiten der Nieren und Harnblase un-
tersucht, 4to. Berl. 1800. Bell, Engravings of
morbid parts, fol. Lond. 1803. Schmidt, Ueber der).
Krank. der Harnblase, &c. 8vo. Wien. 1806. Soem-
mering, Ueber todtlichen Krankheiten der Harn-
blase, 4to. Frft. a M. 1809. Nauche, Des mal.
de la vessie, &c. 8vo. Paris, 1810. Wadd, Cases
of diseased bladder, Lond. 1815. Howship on the
diseases of the urinary organs, 8vo. Lond. 1816.
Coquin du Martel, Vice de conformation des
voles urinaires, &c., in Bullet. de la Soc. Méd.
d’Emulat. Juin 1824. Lallemand, Sur les malad.
des organes genito-urinaires, 8vo. Paris, 1824.
Brodie, Lectures on the diseases of the urinary
organs, &c. 8vo. Lond. 1834. * * * * De.
tharding, De hemorrhoid. vesice, ‘Rost. 1754
(Rec. in Haller Disp. Pathol. t. vii.). et
De ischuria ex tumoribus vesice, 4to. Lips. 1767,
in Kj. Advers. Med, vol. ii. * * * * Salzmann,
De hernia vesicz urinariz, Argent. 1732 (Rec. in
Haller Disp. Chir. t. iii.) Camper, De vesice
herniis, in Ej. Demonst. Anat. Pathol. lib. ii.
Sandifort, De hernia vesice, in Ej. Obs. Anat.
Pathol. lib. i. Roose, De nativo vesice urin.
inverse prolapsu, 4to. Gotting. 1793. Baillie,
Remarkable deviation from the natural structure
in the urinary bladder, &c., Transactions of a
Society for the Improvement of Medical and Chi-
rurgical Knowledge, vol. i. Goeckel, De vesica
spongiosa extra abdomen posita, Miscel. Acad. Nat.
Curios. Dec. 2, A.5. Raiffer, Diss. sur la cysto-
cele ou hernie de la vessie urinaire, 4to. Paris,
1805, Beugin, Diss. sur la cystocele, 4to. Paris.
1805. — Isenflamm, Beschreibung, &c. angebornen,
vorgefallenen, ungestiilpten Harnblase, &c. 8vo.
Dorpat. 1806. Fuchs, Hist. anat. prolapsus nativi
vesice urinarie inverse, 4to. Jenz, 1813. * * * *
Cases of double bladder, by Bordenave, in Mem.
de Chirurg. t.ii.; by Lebenwaldt, in Miscell. Acad.
Nat. Curios. Dec.2, A. 8, 1689; by Tenon, in
Mém. de Paris, A. 1768; by Bussiere, in Phil.
Trans. 1701. * * * * Cases of absence of the bladder,
by Preuss, in Miscel. Ac. Nat. Cur. Dec. 2, An. 7;
by Rengger, in Museum der Heilkunde, B, 2; by
Labourdeite, in Sedillot’s Rec. Period. t. xxxii.
Cases of rupture of the bladder, by J. Johnstone,
in Mem. of the Med. Soc. of London, vol. iil. ;
by Kundmann, in Acta Acad, Nat. Curios. vol. vii. ;
by Montagu, in Med, Communications, vol. ii.; by
Zuinger, in Ephem. Nat. Curios. Cent. 7 et 8; by
Berchelmann, in Acta Hassica, A. 1771 ; by Berner,
in Ephem. Nat. Curios. Cent. 9 et 10; by Schlich-
tung, in Acta Ac. Nat, Curios. vol. vi.; by Hey,
in Med. Obs. by a Soc. of Phys. vol. iv.; by Lynn,
in the same work, vol. iv.; by Sedillot, in Rec,
warlod. t. i.; and by Cusack, in Dub. Hosp. Rep.
vol. ii,

( Benjamin Phillips. )

BLOOD, (Gr. aiva. Lat. sanguis. Fr. sang.
Germ. Blut. Ital. sangue). This is the title
given.to the peculiar fluid which carries into
the living tissues of animals the materials
necessary to the nutritive processes going on
within them.

The physical qualities of this fluid vary
extremely ; anaong almost all the lower animals
it is\so far from resembling what we are accus-
tomed to regard as essential to the blood in
man and the vertebrata generally, that its
nature is at first sight apt to be mistaken, and
we cannot be surprised that the inferiontribes

BLOOD.

of creation should have been long suppos

to be without blood. In the mammalia, bird

reptiles, fishes, and several of the annelida,
the blood is ofared colour ; among the whole of
the invertebrata, a few of the annelida excepted,
it is, on the contrary, nearly colourless ; fre-
quently it has a decidedly blue tint, and in
many instances it is bluish, greenish, or yel-
lowish. A celebrated chemist (Berzelius) has
lately stated that the common fly (one of the
insecta) had red blood in the head, and colour-
less blood in the other parts of its body. It
is true, indeed; that if the head of one of these
insects be crushed, a reddish fluid is forced
out; but this is not blood; it proceeds from
the eyes of the insect, whose blood, in the head
as elsewhere, and among all the other species
of the genus, as well as among the arach-
nida, crustacea, and mollusca, is almost co-
lourless. .

From these differences in the appearance
of the nutrient fluid, the animal kingdom has
been divided into animals having red blood
and animals having white blood. But these
modifications of colour are not perhaps of so
much consequence as has commonly been be-
lieved, for they are met with among animals
having in all other respects the most striking
analogy one with another, as has already been
seen in our particular article on the Anng-
LIDA.

The blood is an opaque, thickish fluid, of a
specific gravity greater than that of water. In
man its density varies from 1,052 to 1,057.
It has a saline and rather sickly taste, and
it diffuses a peculiar odour, which varies
somewhat in different tribes, and occasionally
in the different sexes of the same species,
In all the vertebrata, it is, as we have said,
red; but the shade of this colour varies in
different animals, as it is familiarly known to
do in the same animal, according as it is ex-
amined in its course to the tissues which it is
destined to supply with nourishment, or after it
has already traversed these, and is returning to
the centre of the circulation ; the colour, how-
ever, may be stated to be generally deep.

Examined by the naked eye, the blood ap-
pears to be perfectly fluid and homogeneous ;
but if it be spread in a very thin stratum upon
the object plate of a microscope, and viewed
under a lens having a magnifying power of
between 200 and 300, it will be seen to con-
sist of two distinct and heterogeneous parts,
viz. a transparent yellowish watery fluid, and
a number of solid corpuscles, of extreme mi-
nuteness, suspended in this fluid. To the —
fluid portion, the name serum is given; the —
minute corpuscles are spoken of as the globules —
of the blood. ve

The discovery of the globules of the blood —
is almost contemporaneous with that of the —
microscope; it is due to Malpighi and to
Leuwenhoeck. A considerable number of ob=
servers have since engaged in the micro-
scopical study of the blood; but it is to Hew-—
son and to the Messrs. Prevost and Dumas that —
science is indebted for the most important facts —

BLOOD.

and the best connected series of inquiries into
the composition and qualities of this fluid.*

The form of the globules of the blood varies
in different animals, but appears to be at all
times essentially the same in individuals of
the same species; this at least is the case if we
except the first periods of their embryotic
existence ; for in the embryo the globules have
been found to be different before the formation
of the liver, from what they are after the deve-
lopment of this organ.

The globules of the blood of all the mam-
malia that have been examined are of a circu-
lar shape, whilst in birds, reptiles, and fishes,
they are elliptical; in the invertebrate animals,
however, they are again circular.

The whole of the microscopical observers of
modern times are agreed in the above points; but
they differ in opinion with regard to the nature
of these bodies. This discrepancy, however,
does not appear to us to be owing so much to
any optical illusion to which the microscope
exposes those who use it, as to the choice of
objects made by the different observers. Too
many of them have been satisfied with the
study of the human blood, the globules of which
are extremely small and always seen with great
difficulty, whilst, had they made use of the
blood of certain animals, as of the frog, or, bet-
ter still, of the water-newt (Salamandra cris-
tata), they would have escaped much of the
uncertainty that surrounds their conclusions.

The globules of all animals having red blood
are more or less flattened, and in the greater
number of cases they resemble a small circular
or elliptical dise. Leuwenhoeck was aware of
this fact in reference to birds, reptiles, and
fishes, but he believed that in the human sub-
ject and the other mammalia these bodies were
spherical.t This error, which was sanctioned
by Fontana and various others of the older
observers, and has even very recently been

adopted by Sir E. Home and M. Bauer,t
was, however, completely refuted by Hewson,
Prevost and Dumas, Hodgkin and Lister,
Miiller, &.; my own observations also con-
firm the conclusions of these physiologists,
and even go to prove that the globules of the
blood in the invertebrata have the general form
of flattened vesicles.

The greater number of observers appear to
think that the whole of the globules of the
blood of any animal are of the same dimen-
sions. When blood in which these globules
are very minute is examined, and a low mag-
nifying power is employed, it is quite true
that no perceptible difference in point of size
ean be detected; but by estimating the mag-
nitudes of a great number of these globules com-
Beery and under a powerful microscope,

have satisfied myself that they differed in size

* Vide Hewson on the Blood, and Prevost and
Dumas, Examen du Sang et de son action dans les
diverses phenomenes de la Vie, in Biblioth.
Univers. de Geneve, t, xvii.

+ Philos. Trans. No. 165, 1684, p. 788.

t Ibid. 1818.

405

in the same individual. Among the lower
animals, the river-crab (astacus fluviatilis ) for
instance, it is by no means difficult in the same
drop of blood to perceive globules of very dif-
ferent dimensions ; and although this inequality
is much less remarkable among the higher ani-
mals, I may affirm that it exists. Thus, in the
same drop of a frog’s blood, I have seen globules
that differed from one another in the proportion
of 39 to 45, without my being able to ascribe
these variations of diameter te any circumstance
connected with my mode of observing, or to
any optical illusion: the globules were spread
in a single layer upon the object plate, and so
close together as to be exactly within the focus
of the instrument. Their apparent diameters,
I may state, were estimated by tracing, with
the assistance of the camera lucida, the out-
lines of their images, upon a board eight
inches distant from the eye-piece. I found
corresponding differences of dimension among
the globules of the human blood ; in the same
drop 1 have measured several which were to
each other in the ratio of 112 to 140: in ge-
neral, however, the differences are scarcely
appreciable.

The globules of the blood appear to be
identical in every part of the circulating sys-
tem, and hitherto no difference in their size or
shape has been detected in individuals of the
same species, though of different ages and
Sexes.

It was long found a matter of considerable
difficulty to determine the precise diameter of
the globules of the blood; we consequently
find marked discrepancies in the conclusions
come to by different microscopists. At the
present day, however, and since our means of
observation have been improved, the estimates
have become gradually less and less discordant,
and therefore may be held worthy of the
greater confidence.

From a very great number of measurements
taken by means of the process of M. Amici
(with the camera lucida), and under a mag-
nifying power of 900, I have obtained as the
mean term of the diameter of the globules of
the human blood 5}, of a line (English,) or in
decimal fractions 0,00030 of aline. But as I
have already said, I have found considerable
variety in the sizes of the globules; some,
and these were the largest, were 35 ten thou-
sandth parts of a line, and others, the smallest,
no more than 28 ten thousandths of a line in
diameter.

These estimates accord very nearly with the
last admeasurements published by M. Dumas,
and taken bya different method. He gives
31 ten thousandths ofa line as the mean dia-
meter of a globule of the human blood accord-
ing to his latest observations.*

The conclusions come to by Dr. Hodgkin
and Mr. Lister are also very nearly the same,
these observers estimating the diameter of the

* Annales des Sciences Naturelles, tom. xii.
p. 59

406

globule of the human blood at 33 ten thou-
sandths ofa line. These dimensions exceed,
it is true, the mean of the measurements I
have taken, but they are still within the limits
of the individual variations which I have en-
countered among these corpuscles; and as
the physiologists quoted do not say whether
their estimate was made from the mean of a
number of observations, or from the measure-
ment of only a few globules more apparent
than the rest, it is impossible for me to deter-
mine whence this discrepancy in our conclu-
sions arises, whether from actual varieties,
from the manner of proceeding in determining
the magnifying power of the microscope, or
from an error in taking the limits of the image
projected by the camera lucida.*

The observations made some twelve years
ago by Messrs. Prevost and Dumas do not
differ from the measurements already given.
The diameters they then assigned to the glo-
bules of the blood, amounted to 33 ten thou-
sandths ofa line (44, of a millimetre); but the
magnifying powers they at that time employed
did not exceed 300, and consequently the
difference between the diameter of a globule
315rgG90ths of a line and one 367y¢,5,ths of
a line might fail to be detected; further, the
errors which arise from the determination,
always somewhat arbitrary, of the limits
of the image, are sufficient to explain such
slight differences as occur in the results of
these very delicate observations. We must also
add that Messrs. Prevost and Dumas at this
time made use of a method, much less
accurate than the camera lucida, for taking
the apparent diameters of objects under the
microscope, causing the image seen in the
instrument with the right eye to coincide with
the divisions of a scale placed laterally under
the left eye. We therefore believe our-
selves justified in the preference we accord
to the more recent observations of these gentle-
men.

The late Captain Kater, at the request of
Sir E, Home, also made some observations
with a view to determine the diameter of the
globules of human blood, taking his measure-
ments in the manner formerly employed by
Messrs. Prevost and Dumas, but making use
of a power not higher than 200, by which the
chances of erroneous conclusions were greatly
increased. His first observation, nevertheless,
comes extremely near what we are inclined to
regard as the truth (22;/,,ths of a line); a se-
cond observation, however, gives a much smaller
diameter (13;d5ths of a line), but itis possible
that in this case the observer may have taken
his measurements from a globule divested of
its colouring matter, or perhaps from one of the
albuminous globules which abound in the

* Vide, Some microscopical Observations on the
Blood, &c. in Philos. Mag. Aug, 1827.

BLOOD.

¥
“ay9

serum, and which are in fact very nearly of
the dimensions indicated.* Bs AY

Mr. Bauer and Sir E. Home had pre-
viously assigned 58;4,;ths of a line as the di-
ameter of these globules; but their obser-
vations having been made with the oe
micrometer are necessarily defective, inasmuch
as the globules placed upon this instrument,
and the divisions drawn on its surface, can
never be simultaneously in the focus of the
object glass.+

Dr. Wollaston held that the globules of the
human blood did not exceed 20,4,,ths of a line
in diameter, which is considerably different
from our mean; and Dr. Young did not esti-
mate them at more than 16 ths of a line.f
It is also possible that both of these eminent
individuals have measured the central nuclei of
globules divested of their vesicular envelope.
The results just specified having, farther, been
come to by the aid of the eriometer, an in-
strument which we have searched for in vain
through all the instrument-makers and col-
lections of philosophical apparatus in Paris,
and as we are altogether ignorant of the
degree in which its indications may be relied
on, we cannot discuss these conclusions with
an adequate knowledge of the elements from
which they are derived. As to the measure-
ments published long ago by Jurine, they are
so discordant that no confidence can be placed
in them ; the first diameter he assigned to the
globules of the blood was 19y,4,,ths, the se-
cond 51yphaaths of a line.

From all that has gone before, then, and
particularly from those researches which have
been conducted under circumstances the most
favourable to accurate conclusions, we may
assume the mean diameter of the globules of
the human blood to be about the 31;)),5ths,
or in vulgar fractions the ,};th part of a line.

Messrs. Prevost and Dumas have given the
dimensions of the globules of the blood of a
great number of other vertebrate animals; in
these observations they employed the same
means of estimating the diameters as in their
earliest researches on the size of the globules
of the human blood, so that to me their valu-
ations appear to fall somewhat short of the
truth. This slight presumed inaccuracy, how-
ever, scarcely detracts from the interest of the
general results; for the measurements being
all taken by the same means and therefore
comparable one with another, are adequate to —
show in the clearest light the differences that
occur in the dimensions of these corpuscles in
different animals. The following is the table
of admeasurements given by the physiologists —
quoted. a

«
a a ae
, v

* Vide Additions to the Croonian Lecture,
Philos. Trans. 1818. =

+ Loc. cit. =

¢ Young, Elem. of Med. Literature, 8vo.
Lond. 1818.

BLOOD. 407

NAMES OF THE ANIMALS.

Diameter of the globules
in vulgar fractions of an

Diameter of the globules in
decimal fractions of an =
nglish line. | English line.

MAMMALIA.
Man . . | eee
Canis familiaris, L.
(SIE Rae Sean er
SS ee a eee
Mus avellanus, L. . Se i ate
Lepus cuniculus, L. ee 20 5
Erinaceus Europeus, LL. . . . . . «J
Simia Sabea,
TS ETE a re mer
caw acy ve }
_ Mus musculus . . OF re
Equus caballus, L.
Equus hybridus, L.
Bos taurus, L. . .
Ovisaries, L. . . .
Antelope rupicapra, L. ae in lace
NU Be ki ape igence }
Cervus elaphus, L. sapere

AVES.
Miric flammea, DL. . . .... i
Columba domestica, L. . . . .

Didus ineptu, L. . .....
Anas boschas, do om ¢ hee .
Phasianus gallus, L. .

SS Se ree
ES gee
Corvus coraz, DL. .) one ees a]
Fringilla carduelis, L. §
Fringilla domestica

Parus major, L.

REPTILIA.
Testudo terrestris, L.. ,
enere eS
mepramuis, DL. . .
Co 2 eile .
erta grisea, L. . . . .
Salamandra cincta, L. . . .
Salamandra cristata, L.
Rana bufo, L.. .
Rana esculenta, L. .
Rana temporaria, L. .

PISCES.
Gadus lota, L. . . .

Cyprinus phoscinus, L.
bitis barbatula, L.
Murena anguilla, L.

abs 0,000231

53 0,000328

mW 0,000335

is 0,000220

308 0,000196

343 0,000181

15 0,000104

Great diam. |Smalldiam,} Greatdiam. | Small diam.

aby sho 0,000526 | 0,000231
my id. 0,000500 id.
305 id. 0,000488 id.
oh: id. 0,000463 id.
ite id. 0,000458 id.
ake id. 0,000316 id.
ws on 0,000757 | 0,000512
io ae 0,000657 | 0,000316
= ule 0,000598 | 0,000342
as a fe 0,000658 | 0,000316
thy he 0,000598 | 0,000354
ds a 0,001132 | 0,000704
th 150 0,000877 | 0,000526
1 as -0,000526 | 0,000319

From my own observations I am inclined
to think that the globules of the blood of the
frog have a mean long diameter of about
I6rshe5ths of aline; but the individual differences
observable among the several globules ranged
between 87y5}55 and 100,,1,,ths of a line. In the
blood of the water-newt ( Sulantandird cristata)
I have obtained in my measurements of the
long diameters of the globules the following ex-

treme individual varieties: minimum 106y54,,ths
of a line, maximum 127;5),;ths.

The outline of the globules in all the verte-
brate animals is extremely well defined ; but
they are readily deformed or put out of shape.
Even during life their pressure mutually, or
the pressure they experience between the cur-
rents in which they move and the parietes of
the vessels against which they are driven, suf-

408

fices to alter their form; they are then fre-
quently seen to become elongated, to bend,
in a word, to alter their figure considerably ;
but they are extremely elastic, and readily and
soon resume their pristine state.

Among the invertebrate animals the globules
of the blood are much less regular in their
forms. Their surface is uneven and tubercu-
lated, like that of a raspberry; their contour
is extremely variable; they change their figure
with the greatest facility, and their size
is considerable. In the blood of the river
crab for example (astacus fluviatilis) I have
found their mean diameter to be 70;),,ths
of a line. Several, however, were measured
which were no more than 67y51,,ths of a line
across, and others which were as much as
72pbssths. In the oyster I have detected still
wider differences in the size of the globules of
the blood. In the same drop of this creature’s
blood I found some globules 60;,4,ths, others
only 54y4,ths, and some no more than
AO;A;9ths of a line in diameter.

It is well ascertained that the blood differs
during the earlier periods of embryotic existence
from what it is in after life. Messrs. Prevost
and Dumas have shown that the globules of
the blood in the chick in ovo are circular at
first, and only become elliptical at the period
when the liver is developed.* And M. Prevost
found that in the fetus of the goat these
corpuscles were at first the double in diameter
of those in the adult animal.t

The structure of the globules of the blood,
as well as their magnitude, has been a subject
of great variety of opinion. The differences
in the conclusions, however, appear to me to
depend principally on the circumstances in
the mode of experimenting. Della Torre and
Styles believed that the globules of the blood
were perforated in the centre and fashioned
like rings. When they are examined with
lenses of low magnifying power, they look like
small black points; when viewed under an
instrument rather more powerful, they assume
the appearance of a white circle with a black
point in its middle; this is evidently what has
given rise to the opinion we have quoted ; but
the appearance in question by no means de-
pends on the existence of a central hole in the
globules; it is merely the effect of the light;
for by using a magnifying power of 300 or 400,
the central point assumes the appearance of a
luminous spot, and by varying the position of
the globule, as well as the direction of the
rays of light, the observer may easily convince
himself that the globules are entire. Hewson,
to whom we are indebted for so many good
observations on the blood, was the first who
arrived at accurate conclusions in regard to its
globules. He considered them as flattened
vesicles, in the interior of which there is a
central corpuscle or nucleus. The accuracy of
this opinion, which has been maintained in our

* Mem. sur le developpement du Ceur, &c,
Annales des Sciences Nat. | Serie., t. iii.
+ Ann. des Sciences Nat. t. iv.

BLOOD.

own day by Messrs. Prevost and Dumas and —
others, es en called in question by Dr. Hodg-
kin and Mr. Lister; nevertheless to me it ap-
pees to be founded on unquestionable data.
n studying the blood of the Reptilia, in which
the globules are of very considerable magni-
tude, Messrs. Prevost and Dumas have even
seen the outer envelope of these corpuscles
tear, and expose the central nucleus naked. In
1826 I myself observed that by acting with
a little weak acetic acid on the globules of the
blood, previously placed on the object-plate
of a microscope, they are very speedily stripped
of their envelope, and their central nucleus is
obtained isolated.* ‘Professor Miiller,+ who
does not appear to have been acquainted with
this observation of mine, has lately arrived at
the same conclusions, and has varied his ex-
periments in such wise as to place the results
that follow from them in the clearest possible
light. I shall only further add that at the
moment of writing this article I have again
assured myself of the facts as stated, by sub-
jecting the blood of the river-crab and that of
the frog to renewed examination.

The existence of a solid, white, central
nucleus in the globules of the blood conse-
quently appears to me to be completely de-
monstrated ; and there is, further, every reason
to believe that the peripheries of these cor-
puscles are membranous vesicles formed of
the matter which gives the blood its peculiar
colour, or rather that they enclose this colour-
ing matter between their inner surfaces and the
central nuclei. This vesicular part of the glo-
bule is very elastic: whilst engaged in examin-
ing the capillary circulation in the lungs of
the water-newt, Messrs. Prevost and Dumas
frequently saw the globules change their figure
under the pressure of the moving column of
fluid, and mould themselves in some sort
upon the parts that opposed their advance,
but they resumed their original form the instant
they escaped from the influence of the unequal
pressure.{ In general the tegumentary vesicle
is collapsed upon the central corpuscle, and
thus forms a kind of disc of different degrees of
thinness near the edges, but plump or filled out
towards the middle. By observing the globules
of the blood of the frog and water-newt in diffe-
rent positions, the existence of this central tumi-
dity may be so positively ascertained as to be be-
yond the reach of farther doubt ; but in the hu-
man blood, the globules of which are extremely
small and almost entirely occupied by the
central nucleus, it is more difficult to be satis-
fied of its occurrence; and Dr. Young has
even been led to think that these globules
are discs concave on both sides, an opinion
which has been revived and advocated anew
by Dr. Hodgkin and Mr. Lister. The ap-

* Mem. sur les tissus: Ann. des Sciences Natur.
take ea
+ Observations sur l’analyse de la Lymphe du —
Sang, &c. Annales des Sciences N aturelles, ¢ Sana 5
Zoologie, t. i. p. 559. on
${ Vide Magendie, Physiologie, t. ii.

BLOOD. 409

pearance or disposition of the globules in
question, when it occurs, seems to me to
depend on an alteration of these corpuscles.
In examining the blood of frogs diluted with
thin syrup, the globules occasionally appeared
to me to become turgid, but not to be
distended equally in every part; the exterior
vesicle then remained attached to the centre of
the internal nucleus, whilst it became puffed
all around. I haveseen a globule thus altered
in its form, presenting three very distinct en-
largements in the course of its long diameter,
the two lateral of which exceeded the median
one in extent. I should therefore be led to
imagine that by the effect of an endosmosis
these vesicles may occasionally absorb the
water of the serum, and that this fluid, accu-
mulating around the central nucleus, without,
however, separating this corpuscle from its
envelope, gives to the globule in general the
form of a biconcave disc, as described by Dr.
Young. This appearance, which is very com-
mon in the human blood, agrees extremely
well with the description of Dr. Hodgkin and
Mr. Lister, but we do not imagine that this is the
normal condition, and we are persuaded that
if these very scrupulous observers would but
extend their inquiries to the blood of those
animals in which the globules are most easily
studied, they would return to and espouse
the opinions of Hewson and of Prevost and
Dumas in regard to the particular point at
issue.

In the normal state, the membranous vesicle
of the globules of the blood appears perfectly
smooth among vertebrate animals ; butamong the
invertebrata its surface is uneven and nodulated
like that of a raspberry, as we have already
said. Hewson, however, observed that when
the blood of the vertebrata began to putrefy,
the globules then presented an appearance
analogous to what we have remarked in those of
the crustacea and mollusca. In the mammalia
the central nucleus is circular and depressed,
and in all this class of animals it appears to be
similar in size. In the oviparous vertebrata, it
is on the contrary elliptical in figure, though,
according to Messrs. Prevost and Dumas, it
acquires this figure in consequence of a par-
ticular substance being fixed around it, itself
being in reality circular, as among the mam-
malia.

It frequently happens that other smaller
corpuscles than the globules of which we have
treated hitherto are observed swimming in the
serum. These are of a whitish colour and simi-
lar to the molecules that occur in almost all
the fluids of the animal economy. The resem-
blance that exists between these corpuscles and
the central nuclei of the proper globules of
the blood might lead to the belief that they
were nothing more than the central nuclei
divested of their coloured envelope; but in
several of the inferior tribes, as the river-crab
and certain mollusca, in the blood of which
they occur in very considerable numbers, the
central nuclei of the globules are much larger,
and it is impossible to confound the two toge-

ther. These then are to be regarded, not as
globules of the blood, properly so called,
altered in any way, but as globules of albumen
or fibrine. These substances, in fact, have
always the appearance of being made up of
circular corpuscles of extreme minuteness when
by any means they are brought into the solid
state; and we are led to believe that even
when dissolved or suspended in water they
still preserve this peculiar disposition, and only
escape detection under the microscope by their
dissemination and transparency.

To recapitulate, then, we find :—

ist. That the globules of the blood are mem-
branous sacs inclosing a solid flattened nu-
cleus in the form of a disc, in their interior.

2d. That their form and their dimensions
vary among animals of different species, but
that in the same animal they all bear the
strongest resemblance to one another.

3d. That in the mammalia these corpuscles
are circular and smaller than in any other class
of animals.

4th. That in birds the globules of the blood
are elliptical and larger than in the mammalia ;
their dimensions vary slightly in different
genera, but this variety does not seem to ex-
tend further than to the admeasurements of
their long diameters.

5th. That in vertebrate animals with cold
blood the globules are also elliptical, but that
their dimensions are much greater and vary
more extensively in different classes ; reptiles,
more especially the batrachia, are of all animals
those in which the globules of the blood are
the largest.

6th. That in the invertebrata the globules of
the blood are more or less regularly circular in
shape, and are also of very considerable dimen-
sions.

It appears to be especially owing to the
presence of the globules, the common physical
properties of which we have thus far studied,
that the blood owes its power of arousing and
keeping up vital motion in the animal economy.
We observe, in fact, that if an animal be bled
till it falls into a state of syncope, and the
further loss of blood is not prevented, all
muscular motion quickly ceases, respiration is
suspended, the heart pauses from its action,
life is no longer manifested by any outward
sign, and death soon becomes inevitable; but
if, in this state, the blood of another animal
of the same species be injected into the veins
of the one to all appearance dead, we see with
amazement this inanimate body return to life,
gaining accessions of vitality with each new
quantity of blood that is introduced, by-and-
bye beginning to breathe freely, moving with
ease, and finally walking as it was wont to do,
and recovering completely. This operation,
which is known under the name of transfusion,
proves better than all that can be said the
importance of the action of the globules of the
blood upon the living tissues; for if, instead of
blood, serum only, deprived of globules, be
employed in the same manner, no other or
further effect is produced than follows the in-

410

jection of so much pure water, and death is
no less an inevitable consequence of the he-
morrhage.

A variety of other experiments upon trans-
fusion, for which we are equally indebted to
Messrs. Prevost and Dumas, show the influence
which the form and volume of the globules of
the blood exert upon its physiological proper-
ties. If the blood introduced into the veins
of a living animal differs merely in the size,
not in the form of its globules, a disturbance
or derangement of the whole economy more or
less remarkable supervenes. The pulse is in-
creased in frequency, the temperature falls
rapidly, the alvine evacuations become slimy
and sanguinolent, and death in fine generally
happens after the lapse of a few days. The
effects produced by the injection of blood
having circular globules into the veins of an
animal the globules of whose blood are ellip-
tical, (or vice versa,) are still more remarkable ;
death then usually takes place amidst nervous
symptoms of extreme violence, and comparable
in their rapidity to those that follow the intro-
duction of the most energetic poisons.

We know by observation and experiment
that it is the blood that supplies the living
tissues with the materials which they assimilate
to repair their losses resulting from the vari-
ous processes of which they are the seat, as
well as to add to their masses during the period
of their growth; thus, when by mechanical
means we lessen ina notable and permanent
manner the quantity of this fluid received by
any organ, we soon find it declining in size,
and often shrinking almost to nothing; whilst
on the other hand we see that the more blood
any part receives, the more does it tend to in-
crease in size. It has also been demonstrated
that it is at the expense of the blood that the
different glands prepare the fluids they are
destined to secrete, for the ligature of the ves-
sels which run to one of these organs is followed
by the immediate cessation of its secreting
function. From this it became an interesting
question to determine whether or not the blood
contains, ready formed, the various substances
of which these tissues and these secreted fluids
are composed, and if the organs it traverses
do anything more than merely separate these
from its mass, or whether the general nutrient
fluid only supplies to the different parts of the
economy the primary elements necessary to the
formation of the substances of which we have
spoken, which would then be originated by
the tissues or glands in which they are encoun-
tered. To resolve this question, it became
necessary to contrast the chemical composition
of the tissues and fluids of the economy with
that of the blood, and to ascertain whether the
last-named fluid contained all the variety of
substances which are met with elsewhere in the
animal organization.

This very important part of organic chemistry
is not yet sufficiently advanced to enable us com-
pletely to answer the question: all we know,
however, goes to prove that the component
parts of the tissues and secreted fluids exist

BLOOD. | a
in the blood ready formed, and are only sepa-

cartilages, tendons, ligaments, &c. and which

rated from its general mass by the organs which
at first sight seem to produce them. In the
blood we discover—ist, water, an element
which enters in large proportion into the com-
position of all the fluids, and even forms a
considerable item in the constitution of all the
tissues; 2d, fibrine, which forms the basis
of the muscles: 3d, albumen, which is met
with in variable but still considerable quantities
in the brain, cellular substance, membranes
generally, and in the greater number of the
secreted fluids which are not excrementitious :
4th, a fatty phosporated matter, which enters
into the composition of the nervous system:
5th, a peculiar colouring matter of a yellow
hue, which, slightly modified, is perchance the
same as the pigmentum nigrum of the choroid
coat of the eye, and of melanosis: 6th, phos-
phate of lime and phosphate of magnesia,
salts which form the inorganic basis of the
bones: 7th, alkaline salts, which are met
with in almost all the fluids of the body : 8th,
cholesterine, a peculiar fatty matter existing
very abundantly in the bile: 9th, urea, a
Substance characteristic of the urine: lastly,
various other matters more or less accurately
defined.

Under ordinary circumstances our means of
analysis are inadequate to demonstrate the
presence of urea in the blood ; but if the ac-
tion of the organs destined to separate this
substance from its current in proportion as it is
formed, be arrested, the amount contained
goes On increasing continually, so that before
long it becomes easy to distinguish it. Messrs.
Prevost and Dumas have shown that, after the
extirpation of the kidneys, the blood always
contains urea in appreciable quantity.* This
experiment, the results of which have been
confirmed by Messrs. Vauquelin and Sega-
las, is of the highest importance, and shows
that if we have hitherto failed to discover
uric acid, caseum, and the other compo-
nent elements of the principal fluids in
the blood, we are not, therefore, to conclude
that they do not exist there; analogy would
even lead us to infer that they are actually
present, and that if we were to interrupt
the different glands in the performance of
their functions, they would be discovered
in appreciable quantity. Experiments con-
ducted in this view would be extremely in-
teresting. Another subject of inquiry, too, not
less important, would be to discover the source
of the gelatine which forms the basis of the

does not appear to exist in the blood.

The most complete analysis of the human
blood we possess is that published lately by —
M. Lecanu, a chemist of Paris.+ The careful —
examination of the blood of two strong and —
healthy men afforded the following results.

* Bibl. Univers. de Geneve, and An. de Chemie, _
2de Serie, t. xxiii. ce.
+ Journal de Pharm. No. ix. and x., 1831, 0

PS S|, 2 ~~ —_ =o

;
a
j
;
le

BLOOD. 411

ist Analysis. | 2d Analysis.

Water .
Fibrine .
Albumen .
Colouring matter .
Fatty chrystallizable
matter. . . .-
Oily matter .
Extractive matters
soluble in alcohol
and in water .
Albumen combined
with soda. . .
Chloruret of po- 7)
tassium ae
Chloruret of sodium
Alkaline sub-carbo- >
ame
Alkaline phosphates
Alkaline suiphates . |
Sub - carbonate of °)
lime. eo
Sub - carbonate of
magnesia. . .
Phosphate of lime. >
Phosphate of mag-
DOR.»
Phosphate of iron .
Peroxide of iron . |
Loss

Total

780.145
2.100
65.090
133.000

785.590
3.565
69.415
119.626

2.430
1.310

4.300
2.270

1.790 1.920

1.265 2.010

8.370 7.304

2.100 1.414

2.586

1000.000

2.400

1000.000

Since the publication of the preceding ana-
lysis, M. Boudet has discovered a new substance
in the serum of the blood, which he denomi-
nates seroline. This is a white slightly opa-
lescent substance, fusible at 36 cent., (about
94° Fahr.), not forming an emulsion with
water, soluble in alcohol, not saponifiable,
and appearing to contain azote. This chemist
has also shown that the oily matter mentioned
by M. Lecanu is a mixture of cholesterine and
an alkaline soap, similar to that which is met
with in the bile; lastly, he has determined the
identity of the fatty chrystallizable phosporated
matter contained in the blood with that dis-
covered by Vauquelin in the brain (cere-
brine ).*

The study of the colouring matter of the
blood has engrossed a large share of the atten-
tion of chemists; nevertheless its nature is
still very imperfectly known. It is very com-
monly designated under the name of hemato-
zine or hematine, and can be readily shown to
have the greatest analogy to albumen, from

* Ann. de Chimie, 2de Serie, t. lii.

which it is indeed always separated with great
difficulty. This matter is soluble in pure
water, insoluble in serum and in water impreg-
nated with salt or sugar, coagulable by heat,
capable of absorbing oxygen, carbonic acid,
and various other gases which modify its colour.
According to M. Lecanu the hematine of
chemists is a combination of albumen and the
pure colouring matter of the blood, which he
proposes to designate globuline.* But his
researches into this delicate subject do not
seem to us altogether satisfactory, and we have
reason to believe that his globuline is neither
more nor less than some of the globules of the
blood which have escaped the action of the sub-
acetate of lead employed to precipitate the un-
combined albumen. However this may be,
the colouring matter of the blood after incine-
ration leaves a large quantity of ashes, in
which a considerable proportion of oxide of iron
can be demonstrated, to the presence of which
several chemists have ascribed the red colour
of the blood; such an opinion, however, does
not seem tenable at the present day.

The experiments of Berzelius have shown
that the serum of the blood of the ox does not
differ essentially from that of the blood of man.+
But we are still without comparative analyses
of the nutrient fluids of the different classes of
animals. This desideratum has been partially
supplied in regard to the vertebrata by Messrs.
Prevost and Dumas, they having carefully
determined the proportions of water, and of
albumen contained in the serum, and those of
the fibrine, and other solid parts which swim
suspended in this fluid. From these expe-
riments we learn that the composition of the
serum varies in the same animal at different
times, and that it differs still more widely in
different animals, without its being possible to
connect such changes with the physiological
state of the individual. The case is otherwise,
however, as concerns the globules; in the
majority of cases there exists a remarkable
relation between the quantity of these cor-
puscles and the degree of heat developed by
the vital actions. Of this we may be easily
convinced by inspecting the following table, in
which Messrs. Prevost and Dumas have pre-
sented us with the comparative weights of the
solid particles (globules and fibrine) contained
in 1000 parts of blood, with the habitual
temperature of different animals, taken in the
rectum, the number of pulsations of the heart
per minute, and the number of inspirations
made in the same interval of time.

* Ann. de Chimie, 2de Serie, t. xlv.
t On animal fluids, in Med. Chirurg. Trans.
vol. iii.

412 BLOOD.
. N Ne
Names of the Animals. [so ee g ee ans Mean temperature, Bat pv Pe: of
n 1000 parts minute. {i2Spirations
blood. Albumen. Water. per minute.
' Brrps. ;
We, Stone 15.57 55 945 42° cemtigr. | 136 34
Common fowl . 15.71 75 925 41.5 140 30
EER ORS itp week ar ris 15.01 99 901 42.5 110 21
SOE ae Ne oe asc tS 14.66 66 934 ar on eC
Heron 13.26 68 932 41 200 22
MamMaLia.
Monkey 14.61 92 908 35.5 90 30
Man .. 12.92 100 900 39 i2 18
Guinea-pig 12.80 100 900 38 140 36
Dog 12.38 , 74 926 37.4 90 28
Cat . 12.04 96 904 38.5 100 24
Goat 10.20 93 907 39.2 84 24
Calf. 9.12 99 901 = as ve
Rabbit . 9.38 109 891 38 120 36
Horse 9.20 99 901 36.8 56 16
Sheep 9.00 ee ee 38 ee ee
Repti Lia.
Frog 6.90 50 950 9. in water. és 20
Tortoise .. , 15.06 96 904 7.5 that of the air. a 3
FIsHEs.
Trout 6.38 77 923 s ae ‘%
RAGE he eh cet 1s 4.81 69 931 * o% ie
Pe. co}, toe 6.00 100 900 3 ce a

From these experiments it follows that of all
animals birds are those whose blood is richest
in globules and in fibrine, as they are those
also whose temperature is highest and whose
respiration is most active. The blood of the
mammalia contains rather less, and there is a
difference to be noted in this respect between
the carnivorous or omnivorous tribes, and the
herbivorous, the proportion of solid particles
being larger in the two former than it is in the
latter. We see, indeed, that in man, the dog, and
the cat, they enter in the proportion of twelve
or thirteen per 1000, whilst in the horse, sheep,
calf, and rabbit, they form no more than from the
seventh to the ninth per 1000 of the general
weight of the blood. But the number of species
hitherto examined is not so considerable as to
enable us to say that the circumstance, now
announced, is to be regarded in the light of a
physiological law. Among the cold-blooded
vertebrate animals the blood becomes much
poorer in solid particles; the tortoise, indeed,
seems, from the results in the table, to form
an exception to this fact, but the circumstances
under which the estimates were made in regard
to it, and which it would be too long to enter
upon here, explain the anomaly.*

€ proportion of serum and of solid parti-

cles also presents considerable varieties in the
blood of different individuals of the same
species. From the investigations of M. Lecanu
we observe that the proportion of water in the
human blood varies from 853 to 778 in 1000,
and that of the solid particles from 148 to 68.
The differences of sex have also a certain

* Ann. de Chimie, t. xxiii,

influence on the composition of the blood: M.

Lecanu found in regard to

The blood of man (in 1000 parts.)

Maximum

Minimum
Mean .

Maximum
Minimum
Mean .

The quantity of albumen did not appear to
differ in the blood of the two sexes.

The richness of the blood also varies ac-
cording to the temperament of individuals,
as may be seen by the following table.

Solid particles. Water.
148 805
115 778
132 791
The blood of woman.

129 853

68 790

99 821

Maximum
Minimum
Mean

Maximum
Minimum
Mean

Men.
Sanguine tempe- {| Lymphatic tempe-
rament. rament.

Solid particles] Water||Solid particles} Water —
148 801 117 805
121 778 115 795
136 786 116 800

Women. |
129 796 129 827
121 790 92 790
126 | 793 117 802

———

BLOOD, 413

Lastly, the composition of the blood may
also vary in the same individual according to
a variety of circumstances. Prolonged absti-
nence from diluents, for example, tends to di-
minish the proportion of the watery particles
of the blood, and, consequently, to render it
richer in nutrient elements. Bloodletting pro-
duces the contrary effect; not only is the mass
of circulating fluid by this means diminished,
but it is also rendered poorer. Messrs. Prevost
and Dumas having bled a cat largely, found
its blood to consist of 791 of water, 87 of
albumen, and 118 of globules. Two minutes
afterwards they repeated the bleeding, and now
only found 116 of globules, and 74 of albu-
men to 809 of water; after an interval of five
minutes more the bleeding was repeated for
the third time, and they found the blood to
consist of 829 of water, 93 of solid particles,
and 77 of albumen. M. Lecanu obtained
similar results from the analysis of human
blood taken from patients who had been bled
several times in quick succession, or who were
labouring under hemorrhagic affections ;* and
the circumstance is readily explained, by sup-
posing that the diminution of the mass of

lood tends to accelerate absorption, the first
effect of which must needs be to introduce a
much larger proportion of water than of solid
particles into the torrent of the circulation.

In its ordinary state the blood is always
fluid, and consists, as we have seen, of a
watery part, holding solid globules in suspen-
sion; butundercertain circumstances its physical
properties change completely: this happens
whenever it is withdrawn from the vessels in
which it is contained in the bodies of living
animals, or in the event of an animal ceasing
to exist. The blood left to itself changes within
a few minutes into a mass of a gelatinous con-
sistence, which gradually separates into two
okey one fluid, transparent, and of a yel-
owish colour, formed by the serum; another
solid, quite opaque, and of a red colour, to
which the name of cruor, crassamentum, or
clot is given.

The mode in which this phenomenon hap-
pens, and the cause that occasions it, have
engaged the attention of a great many physio-
logists. The experiments of Hunter and of
many others show that the coagulation of the
blood depends mainly on the cessation of the
motion to which it is constantly subjected in
the course of the circulation ; for this condition
alone suffices to make it coagulate even in the
interior of the vascular system, and we are of
opinion that the great physiologist just quoted
erred in attributing vital properties to the blood.
Rest, then, cessation from motion, is that
which contributes most generally and most
essentially to cause coagulation of the blood ;
other circumstances, however, such as_ its
cooling, its being brought into contact with
the air, &c. may also contribute to accelerate
this phenomenon, which appears, from the
experiments of Dr. John Davy, to be unac-
companied with any evolution of caloric.

* Journal de Pharmacie, 1831.

If a clot of blood be gently kneaded and
wancaty under a stream of water, it gradually

ecomes , paler, and finally loses its red colour
entirely, the colouring matter being washed
away; what remains in the hand is a mass of
whitish and very elastic filaments composed of
fibrine. Or otherwise, if, instead of being left
at rest, a quantity of freshly drawn blood be
quickly stirred with a bundle of rods, a stringy
mass of fibrine will be found adhering to these
after a time, and the blood thus treated will
not coagulate. This experiment shows that it
is to the fibrine that the blood owes its pro-
perty of coagulating.

The filaments of fibrine studied under the
microscope are found to be formed by the
aggregation of a multitude of white globules,
bearing the greatest resemblance to the central
nuclei of the proper globules of the blood.
It was, therefore, natural to suppose that the
formation of the coagulum depended on the
spontaneous decomposition of these globules
and the aggregation of their internal corpuscles.
And such, indeed, is the theory which Messrs.
Prevost and Dumas have given, and which
has been adopted by the greater number of the
physiologists of the present day. “ The at-
traction,” say they, “ which keeps the red
matter fixed around the white globules having
ceased along with the motion of the fluid, these
globules are left at liberty to obey the force
which tends to make them combine and form
a net-work, in the meshes or amid the plates
of which the colouring matter is included along
with a great quantity of particles which have
escaped this spontaneous decomposition.’’*

It would appear, however, that this is not
an exact explanation of the phenomenon, for
Professor Miller, of Berlin, has succeeded in
demonstrating that the coagulation of the blood
is altogether independent of the globules, and
that the fibrine which determines the pheno-
menon exists dissolved in the serum. By filter-
ing with great care the blood of frogs, diluted
with sugar-water, he separated the globules
completely from the serum before coagulation
took place: the fluid part of the blood alone
passed the filter, the solid particles remained
upon it; nevertheless, a coagulum formed
within the fluid after the lapse of a few mi-
nutes; this, of course, was colourless instead
of red, as it is when the red globules are en-
tangled in the mass. This curious and in-
teresting experiment does not succeed so well
when human blood is employed, inasmuch
as the globules, being much smaller than those
of the blood of the frog, pass along with the
serum through almost any filter that can be
used. Still Professor Miller has succeeded
in proving the existence of fibrine in the serum
by means of the following procedure. If toa
little blood contained in a watch-glass a few
drops of a highly concentrated solution of sub-
carbonate of potash be added, the coagulation
of the fluid is so much retarded, that the glo-
bules have time to sink to the bottom before it
occurs. When coagulation takes place at

* Anm. de Chimie, t. 23, p. Sl.

414
length, the clot extends as usual through the

whole mass, but it is colourless on its upper.

part, and only red in the part into which the
globules have subsided. Professor Miiller
believes that the fibrine exists in a state of
solution in the serum, an opinion which to us
appears hardly reconcilable with the known che-
mical properties of this substance ; we are more
inclined to suppose that, like the proper glo-
bules, it is merely suspended in the mass of
the blood in a state of extreme subdivision,
and possessed of transparency too perfect to
admit of its being distinguished amidst the sur-
rounding fluid.

There are circumstances under which the
blood only coagulates with difficulty, or in
which it even loses this property entirely. In
cases of poisoning with hydrocyanic acid, for
instance, the blood remains fluid and _ thick
after death ; the same thing also occurs after
death from fever of a typhoid type, from
lightning, &c.

Another phenomenon presented by the
blood which is of very common occurrence,
and depends on the manner in which it coagu-
lates, consists in the formation of what is
called an inflammatory crust or buffy coat:
the coagulum, instead of being uniformly red,
then appears covered with a greyish or yel-
lowish viscid and very tough pellicle of
various degrees of thickness. The pheno-
menon in question is principally observed in
individuals labouring under acute inflammatory
affections of the serous or synovial membranes,
of the substance of the lungs, &c. but also
occurs among persons in good health, although
plethoric. The experiments of M. Ratier go
to prove that various circumstances, altogether
independent of the physiological state of the
individual, may also exert great influence on
the formation of the buffy coat: thus, ceteris
paribus, it is more readily produced if the
blood withdrawn be received in a deep and
narrow vessel, and if the opening in the vein
be large, and the jet be free. The cause of
the buffy coat has been very satisfactorily ex-
plained; it depends on the more rapid subsi-
dence than usual of the red globules, in con-
sequence of which the more superficial parts
of the coagulum contain none. From the ex-
periments of Professor Miiller it would also
appear that this subsidence of the globules
takes place more quickly if a thick solution of
gum be added to the blood, so as to increase
its density, whilst, when it is deprived of its
fibrine by stirring with rods, these bodies
remain for a very long time suspended. Now
it follows, from the investigations of Sir C.
Scudamore, that buffy blood contains a larger

roportion of fibrine than usual, a state to
which the more rapid deposition of the glo-
bules, and the formation of the inflammatory
crust, which is its consequence, may be at-
tributed.

Thus far we have only spoken of the blood
in a general manner, and without respect to
the part of the system in which this fluid is
examined ; it is, however, very far from being
identical in every part, and there are wide

BLOOD.

differences between the physical and physio-

taacal properties of arterial and of venous
ood. ee

The blood which is tending to the several

_ of the body is in the first place ofa
right vermilion red colour (arterial blood);

whilst that which has already passed through

the different tissues, and is on its way back

from them, is of a dusky or blackish red of

various degrees of intensity (venous blood).

Arterial blood also coagulates more quickly :

than venous blood, and, from the researches

of Dr. John Davy, appears to have rather a

less capacity for caloric,* and a somewhat in-

ferior specific gravity (1,049: 1,051); we are,

however, led to think that in the normal state

the contrary of the latter proposition will be

found to obtain, for Messrs. Prevost and Du-

mas have shown that in this case arterial blood

contains a larger proportion of globules than

venous blood.t+

When the physiological action of arterial
and of venous blood is investigated, still more
striking differences are discovered; the first
maintains vital excitation in the economy, and
the second is insufficient to support life.
Physiologists have even gone so far as to
regard the influence of the venous blood upon 4
the brain as deleterious;{ but more recent
experiments show that though inadequate to
keep up life, it is far from being a poison;
on the contrary, it rather tends to prolong
existence, for frogs whose vascular system is
filled with this liquid die less speedily than
those placed under similar circumstances, but
which have lost almost the whole of their blood
by hemorrhage.§

The blood thus modified by the: influence
of the organs it permeates, is still susceptible
of resuming its primary colour, and of ac-
quiring at the same time its vivifying pro-
perties: it is enough to expose it to the con-
tact of oxygen, to give it back all its peculiar
qualities. We find, in fact, that if venous
blood be agitated with atmospheric air,
or better still with oxygen gas, it speedily
assumes the vermilion tint that characterizes
arterial blood, and if the air thus employed
be afterwards analysed, a certain quantity of
oxygen will be found to have disappeared, and
its place to be occupied with a corresponding
measure of carbonic acid. Now that which
happens here under the influence of mere
chemical affinity, also takes place in the ani-
mal economy, and it is even thus that venous
blood in being exposed to the contact of
atmospheric air in the respiratory apparatus,
whatever its nature, changes into arterial blood
and again becomes fit to minister to life. (See
Respiration.) On the other hand, if ver- —
milion-coloured blood be subjected to the —
action of carbonic acid, it speedily acquiresa —

* Philos. Trans. 1815. tam
+ Ann. de Chimie, t. xxiii. p. 67. <a
t Bichat, sur la Vie et la Mort. See also the —
article ASPHYXIA. ake
§ M. Edwards, Influence des Agens Physiques
sur la Vie, translated by Dr. Hodgkin, a

BLOOD, MORBID CONDITIONS OF THE 415

deep or blackish hue, and then resembles
venous blood in its appearance and pro-
perties.

It now became a question of the very
highest importance in the theory of respiration
to ascertain whether the oxygen acting upon
the blood in the manner specified, produced
the carbonic acid disengaged, by combining
directly with carbon supplied by the colouring
matter or some other element of the blood,
or whether the oxygen was simply dis-
solved by the blood and in dissolving ex-
pelled the carbonic acid which existed in it
ready formed.

Various experiments satisfy us that venous
blood contains carbonic acid already formed.
My brother, Dr. W. F. Edwards, has shown
that those animals which possess the greatest
sidugge of resisting asphyxia continue for a
ong time to disengage carbonic acid when
kept in vessels filled with pure azote or hy-
drogen, circumstances under which it is im-
possible that the carbonic acid evolved can
proceed from the direct combination of in-
spired oxygen with the carbon of the blood.

By placing venous blood under the receiver
of an air-pump, several inquirers had indeed
already found that bubbles of carbonic acid
gas were disengaged from it, when the pres-
sure of the atmosphere was withdrawn. This
fact, first observed by Vogel,* has been verified
by Messrs. Brande, Bauer,t and others. The
quantity of carbonic acid disengaged in this
way, however, is very small, and altogether
inadequate to explain the phenomena accom-
panying respiration; but if, after having freed
a quantity of blood as completely as_ possible
from its carbonic acid by means of the air-
pump, it be agitated with hydrogen or any
other gas, this will be absorbed, and a fresh
and corresponding disengagement of carbonic
acid will be determined. On the other hand
there is an experiment of Girtanner, mentioned
by Hassenfratz,§ which goes to prove that
arterial blood contains a portion of free oxygen
in its constitution ; but this conclusion appears
to require confirmation.

The bright vermilion or dusky red colour of
the blood, however, does not depend solely
on the nature of the gas it holds in solution,
or with which its colouring matter is in com-
bination. The recent experiments of Dr.
Hoffmann shew that the presence of the saline
matters it contains is necessary to the phe-
nomena im question. Blood freed from these
saline seusidione is black, and cannot be
brought to the vermilion red tint as usual b
the action of oxygen. The same physiologist
also ascertained that the presence of an over-
dose of saline matter in blood charged with
carbonic acid, equally prevented the ordinary
action of oxygen in changing its colour.

The blood does not invariably exhibit the
properties and the mode of composition which

* Schweigger’s Journal, Bd. xi.

+ Home, Croonian Lecture, Philos. Trans. 1818.
{ Hoffmann, Lond. Med. Journ. May, 1828.

§ Ann. de Chimie, liere Serie, t. ix.

we have just ascribed to it in the normal state.
There was a time when physicians ascribed
the greater number of internal maladies to
alterations of this fluid; the general errone-
ousness of this opinion, however, was at
length detected, and at the present day patho-
logists have probably fallen into the opposite
extreme, namely, that of neglecting the study
of the changes which the blood does actually
undergo, although these are sufficiently striking
in many cases, and undoubtedly exert an im-
mense influence upon the animal economy.
A careful examination of their kinds and effects
were undoubtedly fraught with results of equal
importance in a medical as in a physiological

point of view.
( H. Milne Edwards. )

BLOOD, MORBID CONDITIONS OF
THE.—tThe nature and properties of blood in
its normal condition having been considered in
the foregoing article, we proceed to notice those
changes to which it is liable in a state of
disease.

That a fluid which is destined to receive and
convey materials for the formation, increase, and
repair of every structure in the animal frame,
which carries away whatever is useless, and is
brought into perpetual contact with the external
atmosphere, should itself be subject to morbid
alterations, is a notion so natural, so entirely in
accordance with what might @ priori be ex-
pected, that, independently of all reasoning, and
antecedently to all proof, it has existed in the
common belief of every age and of every
nation.

To preserve a healthy state of the blood has
accordingly ever been considered an object of
primary importance. The greatest pains have
been taken to maintain its purity, as well in the
individual as the species ; not only in man, but
in all those animals which he has domesticated
for his use; and there is no belief more generally
received than that which attributes the origin
of many of the cutaneous eruptions, and of
most of the cachectic diseases, to the degene-
racy and poverty of this vital streain.

When from this general and popular notion
we advance to the more especial assumption
that the origin of all diseases is to be found in
the blood and other fluids; when we classify
these into hot and cold, moist and dry, or into
blood, bile, black bile and phlegm, and attribute
morbid changes and even natural dispositions to
the prevalence of one or other of these supposed
humours, we quit the belief of the people to
follow theories far less tenable, invented at a
period when authoritative assertions had the
weight of proof, and when the dogmata of a
philosopher were preferred to facts plainly re-
corded in the book of nature.

It would be out of place here to enter into a
discussion of the merits of the humoral pa-
thology as compared with the various doctrines
which have supplanted it, and to which it is
not unlikely that in an improved form it may
again succeed. |

Under the triple relation of vital phenomena,
intimate structure, and chemical composition, as

416

Andral* justly remarks, we can draw no definite
line of demarcation between the blood and the
solids. Physiologically speaking, we cannot
conceive that of these two facts which form a
single whole, the one can be modified without
affecting the other. Since the blood nourishes
the solids, they must necessarily be influenced
by its state; and since the solids furnish ma-
terials from which the blood is formed, and
abstract materials by which it is decomposed,
apy alteration in the nature or quantity of these
must necessarily have its influence on this fluid.
Suffice it then to observe that the further we
extend our knowledge of pathology, the less
shall we feel inclined to admit the exclusive
claims either of fluidism or solidism, and the
more shall we strengthen our belief that the
animal structure is composed of parts, every
one of which may not only partake of disease,
but, under certain circumstances, become its
cause.

Quitting, therefore, all unprofitable specu-
lations on this subject, we proceed at once to a
detail of facts, and to such observations in elu-
cidation of them as occasion may suggest.

Blood may be excessive in quantity, thus
constituting a state of plethora in which the
circulating system is supplied more abundantly
than is needed for the due performance of the
functions of nutrition and secretion. A ten-
dency to accumulation in the capillaries and in
the different internal organs is induced, and con-
gestion with its consequences, or actual rupture
of the bloodvessels, is the result. Drowsiness,
vertigo, headache, epilepsy, apoplexy, mark this
State as existing in the head; dyspneea, and a
livid or purple hue of the skin, as affecting the
lungs; palpitation and irregular action with
Syncope mark the ineffectual struggle of the
heart to propel its contents. Hemorrhages from
the mucous membranes of the nose, the lungs,
or the intestines, are often the consequence of
congestion in the vessels which ramify on their
surface; while indigestion, torpor, and biliary
redundancy, are connected with a plethoric
condition of the abdominal viscera. Although
the existence of such a state, as deducible from
the symptoms just enumerated, as well as from
the effect which depletion has in removing them,
admits of no doubt, it has, nevertheless, not
been made the subject of direct proof. The
proportion which the circulating blood, even in
a healthy animal, bears to its total weight has
not been, and, perhaps, cannot be ascertained
with precision. Haller collects together many
authorities at variance with each other on this
point, and at length comes to the conclusion,
** Neque dissimulandum est, obiter hee et vage
definiri. Intinita enim procul dubio in ratione
sanguinis ad reliquam corporis molem varietas
est.” +

Fat men and animals have less blood than
lean, old than young; and yet plethora is
oftener found in the former than the latter,
obviously on account of the mechanical im-

* Précis d’Anatomie Pathologique, P 526. -
t Elementa Physiologie, tom. ii. p. 5.

BLOOD, MORBID CONDITIONS OF THE.

pediment which the encumbered tissue or the
rigid fibre offers to the circulation. — .

The state of anemia, or a deficiency in the
quantity of circulating blood, whether induced
by natural or artificial causes, is no less detri-
mental to health than its excess. Its symptoms
are general pallor, weak circulation, languor,
syncope with palpitations, oppressed respi-
ration, flatulency, general cedema, and, in
extreme cases, effusion into all the serous
cavities. :

Neither plethora nor anemia necessarily
imply, though they are generally complicated
with some morbid change in the blood itself.
We therefore pass them over with this slight
notice, referring for further information to the
excellent observations of Andral, in his work on
Pathological Anatomy.

The circulating blood consists essentially of
a homogeneous fluid and red particles, and the
former, when removed from the body or from
the circulation, separates into a fluid and a solid
portion. The solid, when washed and freed
from the serum and red particles which are
mechanically entangled in its substance, consti-
tutes the proximate animal principle called
fibrine. The fluid contains water, albumen,
oil, animal extractive, and salts, alkaline, earthy,
and metallic.

With the exception of the oil and fatty
matter, which, in a healthy state of the blood,
do not amount to four parts in a thousand, its
constituents are all heavier than water, and
something is to be learned by ascertaining
its specific gravity. In the information thus
gained, however, we are limited to the al-
ternative, either that some one or more of these
constituents is in a state of excess or of de-
ficiency, the proportion of water remaining
normal, or that the water itself is either su-
perabundant or deficient.

The specific gravity of healthy blood has
been variously stated by different authors.
Haller makes it on the average 1,052; Blu-
menbach, 1,054; Berzelius, from 1,0527 to
1.057; Denis, 1,059; but none of these au-
thors note the temperature at which it was
taken, although, from their manner of ascertain-
ing it, there must have been considerable
variety in this respect. By experiments which
I have often repeated with an accurate specific
gravity bottle holding 1,000 grains of distilled
water, I find that with that fluid four degrees
of Fahrenheit’s thermometer corresponds with
a difference of :001 of specific weight, water
being 1,000. Consequently, if one author
states the specific gravity of blood at its cireu-
lating temperature 98° Fahrenheit, while an-
other states it at 60° Fahrenheit, the usual
standard, the former will make it ‘0095 lighter
than the latter.

The heaviest blood of which I find a record
among my own observations was that of.a man
suffering under diabetes mellitus. At a tempe-
rature of 87° Fahrenheit it was of specific gra-
vity 1:0615, while that of the serum was under
the average standard of health, namely, 1°027
at 60° Fahrenheit, and of the medium propor-
tion to the crassamentum, being, after twelve

BLOOD, MORBID CONDITIONS OF

hours’ rest, as 1000 to 1323. The specific gra-
vity of the crassamentum was 1-088.

The lightest blood which I have met with
was of specific gravity 1:031, at 90° Fahren-
heit. It was taken from the arm of a female,
aged 22, who was bled on account of headach,
and had a full pulse of 117.

The red particles being the heaviest of all
the constituents of the blood, their relative
quantity must greatly affect its specific gravity ;
and as Messrs. Prevost and Dumas have shewn
that they bear a general proportion to the de-
gree of animal heat, we might reasonably su
pose that, ceteris paribus, the heaviest blood
would be found in those diseases which are
marked by high action and increased tempera-
ment. Ina fluid so complicated, however, in
which every constituent is liable to such variety
in quantity, it is difficult to estimate the precise
influence of each. I am not aware that any
experiments have been made on this subject.

Blood diminishes in specific gravity in pro-
portion to its frequent abstraction, for the red
particles and the fibrine are reproduced with
more difficulty than the serum or the salts. The
serum also becomes lighter from a gradual di-
minution of its solid contents. A recent paper
by Mr. Andrews, in the fifteenth- volume of the
Medical Gazette, p.592, proves these facts very
Satisfactorily by experiments made on calves.
Tae have, however, been long known.

_ the specific gravity of morhid blood, says

_ Thackrah, differs little from that of healthy

blood ; but this observation is only true of an
average deduced from numerous specimens of
blood examined under different forms of dis-
ease. It would be equally true, perhaps,
according to the same mode of obtaining a
result, were we to affirm that the temperature
of the body or the state of the pulse differed
little in health and disease, since there might
be as many instances of deficiency as of ex-
cess in heat or action. The assertion is not
applicable to particular cases, and is, therefore,
without value. Blood may be morbid from
an undue proportion of any of its constituents,
and it will be heavier or lighter than healthy
blood according to the preponderance of the
heavier or lighter principles. Where the spe-
cifie weight is increased, it is generally owing
to a deficiency in the proportion of water, as in
the blood of cholera and diabetes; sometimes
to an increase of fibrine and red particles, as in
plethora, gout, and rheumatism.

The following table, containing the specific
gravities of blood under several forms of dis-
ease, is compiled from a few cases of my own
which were recorded for another purpose.
Though short, it will be sufficient to shew that
considerable variety occurs, and may collaterally
suggest that in determining the propriety of de-
pletion, it may in some cases become impor-
tant thus to ascertain the proportion of solid
matter existing in the circulation. A specific
gravity bottle, holding 1000 grains of distilled
water, was employed in all the experiments, so
that the bcs a of serum to clot was not
influenced by variation in the shape or material
of the receiver.

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418 BLOOD, MORBID CONDITIONS OF THE.

The specific gravity of morbid serum has
been much oftener ascertained than that of
morbid blood, and it leads to more precise
information. The normal proportion of salts
does not raise the specific gravity of serum
above that of distilled water more than five parts
in 1000.* The excess beyond this increase is
owing to the presence of albumen. The quan-
tity of other animal matter is too small to be
worth taking into the account. Hence the spe-
cific gravity of serum indicates with tolerable
accuracy the quantity of albumen it contains.

In some states of disease, where albumen is
rapidly carried out of the system, as in dis~
eased kidneys, in dropsies, and in profuse
hemorrhages, the specific gravity of serum has
been observed as low as 1:013,+ whilst in other
states, where water and even salts are removed,
as in cholera, it is found as high as 1°041.f

Neither the specific gravity of fibrine nor of
red particles has been hitherto stated by authors.
The former, by immersion in solution of salt, I
find to be 1:079 at 60° Fahrenheit. Some of
the latter will fall to the bottom of a solution
of specific gravity 1°129, and when agitated
with a solution of even specific gravity 1°207,
which is the point of saturation, will not rise
to the top; but the experiment is not con-
clusive, for the red particles certainly undergo
some change by the addition of salt in solution.

The temperature of the blood is materially
influenced by disease. In fevers it is generally
though rot always above the healthy standard.
In the cold stage of an intermittent the tempe-
rature of the skin has, according to Dr. Wilson
Philip, been observed as low as 74° Fahren-
heit, while in its hot stage it has increased to
105°. A corresponding diminution or increase
in the temperature of the blood in all probability
occurred in these cases. Haller cites authorities
to prove that in pleurisy and yellow fever the
temperature of the blood has been known to rise
to 102° and 104°, in intermittent fever to 106°
and 108°, and in continued fever to 109°. Mor-
gagni devotes several pages to the history of a
woman, as related in the journal of a cotempo-
rary, Media Via, whose blood flowed in an
icy cold state from the arm. The serum of
this blood was in small proportion and of a
yellow colour; the crassamentum black and
viscid. This person seems to have undergone
repeated venesection.
similar phenomenon.

Whatever theory may be adopted respecting
the generation of animat heat, it is a fact which is
generally admitted, that it is effected through
the medium of the blood, that it is, ceteris
paribus, increased in proportion to the velocity,
freedom, and force of the circulation, and that it
is mainly dependent for its development upon
the presence of the red particles. Wherever
these are deficient, either from natural disease
or artificial depletion, animal heat is deficient
likewise. Chlorotic females and those who are
subject to habituat losses of blood usually

* Med.-Chir. Trans. vol. xvi. part i. p. 57.
+ Bright’s Reports, vol. i. p. 85.
t O’Shaughnessy’s Report on Cholera, p. 29.

Thackrah witnessed a.

suffer from coldness of the extremities. The
henomenon of fainting is always accompanied
te diminished temperature ; and whenever we
cut off the supply of blood from a limb, it loses
its natural warmth as an immediate conse-
quence. Plethoric subjects, on the contrary,
provided their circulation be unimpeded at its
capillary extremities, or in the ee of the
pulmonary ventilation, are lia
natural heat of the surface and profuse perspi-
ration. As an actual diminution or increase in
the quantity of the red te produces a
corresponding increase or diminution of animal
heat, notwithstanding the natural change of
venous to arterial blood, so likewise any cause
which impedes that change, although the red
particles be not deficient in quantity,will produce
a like effect. Thus, in diseases of the heart, in
pulmonary obstructions, especially of a spas-
modic character, in the cold fit of ague, and in
Asiatic cholera, there is a diminution of the
natural warmth, although there is no reason to
suppose that the red particles are actually less
abundant than in health. .

Fibrine may undergo alterations in quality
during disease. In the healthy state it is com-
posed of definite quantities of oxygen, hydrogen,
azote, and carbon ; and it is quite possible that
some variety in the proportion of these consti-
tuents may give rise in disease to morbid states
of that principle. Huxham observes that in
malignant petechial fevers the ‘crasis is so
broken as to deposit a sooty powder at the
bottom of the vessel, the upper part being either
a livid gore, or a dark green, and exceedingly
soft jelly. De Haen saw the blood in a dis-
solved state, and in the plague the blood is
said not to coagulate.

In some persons there exists a state of con-
stitution, bordering no doubt upon passive hz-
morrhagic disease, in which the blood is ob-
served either to coagulate very imperfectly or
not at all. Alarming hemorrhages from the
slightest wounds are the consequence of such a
diathesis, and the most powerful styptics will
not always succeed in preventing their fatal
termination. Dr. Wardrop, in a small work
just published, has collected together several
interesting cases of this kind, and from some of
these it is demonstrated that such a condition
may exist in many members of the same family,
and even sometimes become hereditary.

In the dead body blood is sometimes found
in a liquid state, resembling water, holding in
suspension a red, brown, or black colouring
matter. In this case, according to M. Andral,
it has been demonstrated chemically that it
still contains fibrine, but altered in its character,
so as to be no longer coagulable. This dis-
solved state of blood observable after death is
probably the same as that which exists in sea-
scurvy, in putrid and typhous fevers, and in
the latter stages of fatally terminating diseases
characterized by defective nervous energy. It
is matter of more common observation, how-
ever, that fibrine alters materially in its relative
quantity. We often find that the clot is large
in proportion to the serum, which may indeed

arise from its being loose and defective in con- —

le to preter- —

aes

———————=—————<«_ = —-— -—:~—”— -~.~~~+«o Ft

- ™

BLOOD, MORBID CONDITIONS OF THE. 419

tractility, so as to contain a large portion of
fluid, or from its holding entangled among its
meshes an unusual number of red particles;
but it will often also arise from there being a
more than ordinary quantity of fibrine present,
in which case it will be firm and contractile as
well as voluminous. Blood thus cireumstanced
is said to be rich and thick, and is generally
met with in those whose complaints are con-
nected with a plethoric habit.

A deficiency in the proportion of fibrine is
likewise not unfrequent among those who suffer
from complaints of debility, or who have lost
much blood by natural or artificial depletions.
In this case the clot is small, and has but little
contractile power.

It is, I conceive, a possible case, that the
fibrine may separate imperfectly or not at all,
in consequence of an augmented proportion of
salts, which out of the body we know to be
capable of suspending coagulation altogether.
The continued use of alkaline remedies will
probably tend to produce a like effect.

Fibrine coagulates the more speedily in
porportion as the circulating and nervous sys-
tems become more feeble. The experiment
has been repeatedly made with animals that
are killed by tiseding, and the last por-
tions of blood invariably coagulate soonest.
“The principle of the blood’s speedy con-
cretion in debility is important in a curative
point of view. The first natural check to he-
morrhage is known to be the formation of a clot
on the mouth of the vessel. Ifthe longer the
hemorrhage the less had been the disposition to
form such a clot, the wounded on the field of
battle, and those injured by common accidents,
who cannot promptly procure the aid of a
Surgeon, must inevitably have perished.’’*

One of the most remarkable and frequent de-
viations from the normal condition of blood
removed from the body by venesection, is the
oceurrence of the buffy coat, which is a layer of
fibrine occupying the surface of the crassa-
mentum. e blood, whilst circulating within
its vessels, consists, as I have already remarked,
of a fluid which I have elsewhere ventured to
call liquor sanguinis, and of insoluble red_par-
ticles. These being in constant motion are
uniformly diffused throughout this liguor ; but
their feng gravity being much greater than
that of the medium in which they are sus-
pended, they have a tendency to gravitate when-
ever that motion ceases. In healthy blood the
fibrine coagulates so quickly that the red par-
ticles have not time to subside, so as to leave
any portion of the liquor entirely free from
them. By protracted fluidity this result is
effected ; the red particles do then gravitate to a
greater or less depth before the liguor separates
into two A general coagulation of the
fibrine at length occurs, and a clot is formed.
That part of it through which the red particles
had fallen becomes a layer of fibrine from
colour, and merely having some serum mecha-
nically retained in its meshes, while the sub-
jacent portion is of intense depth of shade,

* Thackrah, P- 188.

especially at the bottom, and of less than ordi-
nary cohesion. In extreme cases, such an
abundance of red particles reaches the bottom
of the vessel that they are there found in a
state of fluidity. The buffed layer sometimes
assumes a cupped form, which is clearly owing
to unequal contraction. The upper surface
being freer from intervening red particles, con-
tracts more powerfully than the under, and a
concavity of the surface is the necessary con-
sequence. Where, however, the contraction is
weaker, the weight of the subjacent red clot,
which is one and the same mass with the upper
colourless portion, weighs this down, and keeps
it in a horizontal position.

The crassamentum of arterial as well as of
venous blood has frequently been observed to
exhibit a buffy coat. It is rarely seen in blood
extracted by cupping-glasses, and never in that
pressed from leeches. It occurs in the lower
animals, and is observed as frequently in the
horse as in the human subject; indeed, from
the quantity of blood usually drawn from that
animal, it is still more strikingly apparent, being
occasionally several inches thick. It has been
denied that the cupped appearance is ever met
with in the blood of the horse; but if this be
received into a sufficiently small vessel, it will
be in some instances as complete as in blood
taken from the human subject. There are va-
rieties in the appearance of the buffed coat
which it is worth while to notice. It is gene-
rally of a firm uniform consistence, and of a
light yellow or buff colour, whence its name.
Sometimes, however, it is of a more spongy
texture, and of a white or bluish, and more
transparent hue. Two layers of buff are occa-
sionally seen ; the upper soft or friable, the in-
ferior more compact. “There is a difference,”
says Sir Gilbert Blane, “in the appearance of
the blood when sizy, perhaps not sufficiently
insisted on by practical writers; for though
there should even be a very thick buff, yet if
the surface is flat, and the crassamentum tender,
no great inflammation is indicated in com-
parison of that state of the blood wherein the
surface is cupped, the crassamentum contracted
so as to form the appearance of a large pro-
portion of serum, and where it feels firm and
tenacious, though perhaps but thinly covered
with buff.’””*

From the examination of several specimens
of buffed blood, I was at one time led to be-
lieve that its serum was always deficient in
its due proportion of albumen; but this I have
since found not to be the case, having met
with blood thickly buffed, the serum of which
at 60° Fahr. had a specific gravity of only
1°024, and with another specimen where the
layer of fibrine was equally thick, of which,
at the same temperature, the serum had a spe-
cific gravity of 1-040. Dr. John Davy examined
the specific gravity of buffed blood in eleven
cases. In five of them in which the buffy
coat was slight, the specific gravities were 1-047,
1°051, 1:054, 1°055, 1°054; in five others in
which the buffy coat was moderately thick, the

my Blane on the Diseases of Seamen, note.to page

2 Bee

420

Specifie gravities were 1°:044, 1:038, 1:052,
1:056; and in one instance in which it was
thick, the specific gravity was 1057. Taking
the mean gravity of healthy blood at 1:044,
which I believe will be found correct, it would
thus appear that the buffy coat is more frequent
in blood above than below the mean weight;
but it is also clear that it may exist in either
state, and the number of experiments is not
sufficient to lead to any conclusive result.

De Haen, Hewson, and others have met with
cavities in the crassamentum of buffed blood
containing clear fluid (liquor sanguinis), which,
on being evacuated several hours afterwards,
separated into fibrine and serum. This fact is
analogous to that of fluid blood having been
found by Hewson in the heart of a dog thirteen
hours after death, which blood, on being re-
moved, coagulated soon after exposure to the
air. A similar coagulation will occasionally
take place in fluid blood taken from the human
heart several houis after the extinction of life.

The remote cause on which the occurrence
of the buffy coat depends appears to be an
increased action in the circulating system, de-
pendent on increased nervous energy, and this
is capable of being very speedily excited. Thus
it has happened* that blood from the same
orifice drawn into four cups has exhibited this
appearance in the second or the third cup,
and not in the first or last, the difference being
plainly owing to a faintness felt at the com-
mencement and termination of the venesection.
Thus also the blood of healthy horses drawn
immediately after a smart gallop while the cir-
culation is powerful and rapid, will exhibit a
buffy coat, while that previously abstracted
will of course shew no such appearance.
Scudamore, it is true, arrived at an opposite
result in the case of a young man whom he
bled, and after causing him to run two miles;
bled again. Neither before nor after the race
was the blood buffed, but it is obvious that such
severe exercise after depletion would exhaust
rather than augment the powers of the nervous
and circulating systems. Accordingly he found
the proportion of fibrine diminished in the blood
last drawn, while the specific gravity of the
serum was increased from 1°030 to 1:035, thus
shewing how large a quantity of moisture must
have been carried off by perspiration.

The buffy coat, as might be anticipated from
its cause, is usually found in connexion with
those diseases and even conditions of health
in which vascular action is _preternaturally
increased—in the active stages of peripneu-
mony, in pleurisy, in inflammatory fever, scar-
latina and the eruptive diseases generally, and
very uniformly in acute rheumatism. It is
also occasionally but not always met with in
the blood of pregnant women, in persons of
sanguine temperament and full habit, and those
who resort to frequent bloodletting ; in chronic
rheumatism, gout, enlargement of the heart,
and other affections where no inflammation
exists. On the other hand, it may be absent
even in the most intense inflammation; for the

* See Hewson on the blood, vol. i. p. 82 et seq.

BLOOD, MORBID CONDITIONS OF THE.

- by humerous authorities, that these have be

circulation may be so overcharged — i.
actually pr nee or the he Boe ( me a
oppressed, that the requisite degree of propul-
sie force is not sansa by the thea: AB ee
arteries, nor the vital energy on which slow
coagulation depends imparted to the blood.
In such instances the buffed coat generally
appears on a second or third repetition of
venesection. Se

Louis found the blood covered by a firm
thick buff at each bleeding in nineteen cases
of fatal peripneumony out of twenty-four. In
two-fifths it was cupped. In fifty-one out of
fifty-seven cases of recovery the blood was
buffed, and in twenty-three cupped. In nine
tenths of rheumatic patients the buff was firm
and thick.

The form of the receiving vessel, the degree
of motion to which it is subjected, and the
size of the orifice in the vein, materially in-
fluence the phenomenon. M. Belhomme, the
experimenter under M. Recamier, has made
about one hundredand fifty experiments on blood
drawn in health and disease. He has come to
the conclusion that a medium orifice one line in
the vein, a strong, rapid, and continuous jet in
the form of an arch, and a narrow vessel for
the reception of the blood, are the external
circumstances most favourable for producing
the buffy coat.*

Fibrine is more abundant in buffed than in
healthy blood. Dr. Davy, from his observa-
tions, infers that there is no constant relation
between the appearance of this covering and the
proportion of fibrine in the crassamentum, yet
his own tabular report contradicts him. “ From
all the examinations we have made,” says
Thackrah, who has made many experiments to
determine this point, “ I infer without hesita-
tion that buffed blood contains a considerabl
greater proportion of fibrine than healthy
blood.” This is a fact of much interest and
importance, for as very slight aud sudden causes
may give rise to the formation of a buffed coat,
we are thence led to infer that the quantity of
insoluble matter which separates from liquor
sanguinis by coagulation is variable, and that
there is so far reason to believe that fibrine and
albumen are principles convertible into each
other. é
In connection with the appearances depen-
dent upon the slow coagulation of fibrine, I
may here notice the occurrence of what have
been termed polypi, or more recently and cor-
rectly, false polypi in the heart and larger ves-
sels. These are so common, that, as Haller ob-
serves, scarcely a body is met with in which —
they do not exist. They are found in both
auricles and both ventricles and in the larger
arteries and veins, as well of the trunk as of th
extremities. They consist essentially of fibri
and partake of all the varieties that are o
vable in the fibrinous coat of buffed blo
Haller affirms, as usual, supporting his opir

known to exist even during life, not onl;

a

. res
* See also Med.-Chir. Trans. vol. xvi. p. 296,
note. fs eee v ery

_ often occurs.

BLOOD, MORBID CONDITIONS OF THE.

man but in the larger warm-blooded animals,
and adverts to a disease, la gourme, common
among horses, which arises from a coagulation
of the blood in the large arteries and veins and
in the heart. Thackrah is of the same opinion,
and Dr. George Burrows, who has made the
changes which take place in the blood when

its circulation is stopped in the living body,

the subject of the Croonian Lectures of the
present year, states that “there can be but
little doubt that in some cases the blood coa-
gulates in the heart during life. The firmness
of the clots found in its cavities after death—
their close adhesion to the lining of the heart—
the presence of various fluids in the centre of
these clots—the occasional organization of the
coagulated masses, and their partial conversion
into structures which are similar to new growths
in other parts of the body—are facts which
lead us to the conviction that the blood often
coagulates in the heart long prior to death.”
That such coagulation may take place during
life I am willing to admit, but I am by no
means led to the conviction that such an event
To the formation of a firm coa-
gulum I am persuaded that rest is absolutely
necessary, and I must consider it as a very rare
occurrence that the contents of the cavities'of the
heart should be at rest during life. The usual
appearance of false polypi is such as would
take place in blood that coagulated very slowly,
whether in or out of the body. Mr. Thackrah
has proved that the blood when at rest coagu-
lates much more slowly in living vessels,
among which his experiments include vessels
recently removed from living animals,* than in
those that are dead; and I conceive that the
human body, long after the heart has ceased to
beat, and when it is, in the common accepta-
tion of the term, dead, is still endowed, like
the vessel just separated from the living animal,
with a sufficient share of vitality to keep the
blood which is in the heart and larger vessels
in a fluid state, and thus to permit its coagula-
tion to take place at length far more slowly
than under ordinary circumstances. The fol-
lowing fact will perhaps be considered to have
some interest as bearing on this point. I was
engaged in the post-mortem examination of a
gentleman who had died apoplectic from soft-
ening of the brain, which had given rise to effu-
sion into the ventricles and under the pia mater;
and being desirous of examining the fluid thus
effused, I collected it with a clean sponge, by
successively dipping this into the ventricles, and
Squeezing the fluid into a small cup. With a
view to increase the quantity, I used the sponge
also in soaking up some of the same fluid
which had been caught in the calvaria, but
Was somewhat tinged with red particles. The
cup was set apart till the conclusion of the ex-
amination, which lasted an hour and a half,
when, on proceeding to transfer its contents to
‘2 Po I was not a little surprised to find that
a bulky clot of a rose colour and perfectly dis-
tinct was formed in the fluid. The examina-
tion in question took place twenty-two. hours

* Thackrah on the Blood, p. 85, expt. lii. & liii.

421

after death. As long as galvanism will stimu-
late the muscular structures to convulsive
movement, so long at least may we conceive
such a portion of vitality to remain as will in-
fluence the state of the blood. The fluid thus
circumstanced exhibits the same phenomena,
though in a more marked degree, which we ob-
serve in buffed blood out of the body. The
red particles subside and leave the liquor san-
guinis free from colour. In due time this
separates into fibrine and serum: the coagula-
tion takes place uniformly and universally, and
in the larger cavities and vessels a colourless
clot is left, which is moulded into their exact
shape. The serum drains off, and washes away
the red particles into the more depending and
distant vessels. Thus it is that where we find
polypi in the heart, we often find the descend-
ing aorta and the vena cava inferior filled with
fluid, in which there is no fibrine at all. The
firmness of a polypus affords no proof that it
existed during life, or rather before respiration
and circulation had ceased; for what can be
firmer than the buffed coat which we often see
formed out of the body? Its close adhesion to
the lining of the heart is generally in appearance
only, and is occasioned by the exactness with
which it has adapted itself to every cavity and
sinus, and enveloped every column, and the
force with which the heart itself has contracted
upon it. The presence of fluid in the centre,
however difficult to account for, is also occa-
sionally met with in the crassamentum of blood
abstracted from the arm;* and even purulent
matter, said to be found in false polypi, is oc-
casionally formed out of the body. “ In some
rare cases I have seen the fibrine,” says Andral,
“assume a different aspect. The blood had
no clot, and instead of it we ubserved at the
bottom of the basin a kind of homogeneous
purulent matter of a deep brown or dirty grey
colour, and rather resembling sanies than
blood.”

With regard to the existence of organization,
it seems to me that sufficient distinction has
not usually been made between those cases
where the lining membrane of the cavities of
the heart or vessels has been ruptured, and
which in so far are of the character of aneu-
rism, and those where that membrane has re-
mained entire. I am willing to admit that
where there is a lesion of surface, adventitious
growths will readily spring from it; but their
substance is furnished from the structure be-
neath, and not from the circulating fluid. As
an instance, I may mention the case of a youth
who, being in perfect health, received a sudden
shock from the unexpected discharge of a pistol
close to his ear. He immediately felt conscious
that something had given way in his heart, and
from that hour suffered from palpitation, occa-
sional syncope, with the usual symptoms of
obstructed circulation, and died of general
dropsy at the end of eighteen months. On ex~
amination after death the mitral valve was
found to be obstructed by a fringe of excre-
scences, originating no doubt from a rupture of

* See Hewson, p. 69 and 70.

422

the valve itself, which had taken place at the
time of the sudden surprise. is kind of
growth, as well as that which is formed on the
inflamed surface in endocarditis, has a suffi-
ciently evident origin. We can also readily
account for organized structures arising from
aneurisms of the heart or arteries, accidental
wounds of the latter vessels, ruptures of their
inner membrane by ligatures, or its destruction
by inflammation. I can, however, imagine
nothing more unlikely than that an insulated
mass of fibrine owing its origin to the mere
coagulation of the blood from rest, and there-
fore only by gravitation brought in contact with
the sides of the vessel which may contain it,
should assume an organized structure, and that,
too, ata time when the powers of life are so
much enfeebled that the heart itself ceases to
perform its office. I have looked carefully for
unequivocal signs of vitality in these false
‘polypi, and I confess that I have never been
able to satisfy myself of its existence.

The albumen has not been demonstrated to
be subject to alteration in quality. Its distin-
guishing characteristic of coagulating by heat is
preserved even after it has become in the high-
est degree offensive from putridity.* It may
be excessive or defective in proportion, and M.
Gendrin has shewn that under inflammation
of the system, the serum contains twice as much
albumen as in the healthy state. Andral affirms
that even by the touch, we may, from its vis-
Cidity, recognise serum that is surcharged with
albumen. Its specific gravity, however, of
which the French writers seem to take little
note, would be a far better guide, and would
indicate alike the defect as the excess of this
principle. M. Gendrin has occasionally ob-
served a mucous layer either at the bottom of
the serum, or suspended in it. This is, in
all probability, a minute portion of fibrine se-
parating in the form of a flocculent cloud ; for
serum is capable of holding a certain portion of
fibrine in solution, which after a time separates
from it. This was first proved by Dr. Dowler,+
who, on pressing the buffed coat of blood, ex-
tracted from it a liquid serum, which, on being
allowed to rest for some time, exhibited signs
of coagulation. With regard to the relative
proportions of the serumand the clot, I have
proved elsewhere} that this depends much on
the vessel into which the blood is received. I
shall show experimentally, however, in treating
of diseased kidney, that an opposite state to
that above alluded to as occurring, according to
M. Gendrin, in inflammation, takes place under
certain forms of disease where albumen is
passing out of the system by the urinary pas-
sages. Thackrah lays it down as a law, to
which he has found no exception, that in all
cases in which the proportion of fibrine is con-
siderably above the normal standard, the solid
matter in the serum is below it. He cites ten
examples in proof of his assertion, and puts it

* See a paper by M. Vauquelin, in the 16th
vol. of the Ann. de Chimie, new series, p. 363.

+ See Med.-Chir. Trans. vol. xii. p. 8d,

¢ Med.-Chir, Trans. vol. xvi. p. 296.

charge of blood by vomit and stool ; another of

BLOOD, MORBID CONDITIONS OF THE.

pose that the albumen is taken from the serum
for the formation of fibrine? The fact itself,
however, requires confirmation, being in direct
Opposition to M. Gendrin’s statement, that the
proportion of albumen is greatly increased in an ‘
inflammatory condition of the system, which is
precisely that condition when in general we
find buffed blood, and therefore, according to
Thackrah, an increase in the proportion of
fibrine. \. *
The hematosine is the least destructible of :
)
|

as a question whether we may not hence sup-

all the elements of the blood, retaining its quali-
ties in that fluid after having been kept for
several years. It is liable to much variety in
its proportion, and in all those diseases and
States of system in which hemorrhages occur, it
gradually diminishes, at least to a certain point,
in proportion to their extent and duration.
In what part of the system the red particles
are elaborated remains for the present a mys-
tery. That they are reproduced slowly is
manifested by the fact that those who have suf-
fered large losses of blood, remain exsanguine
for many months or even years afterwards.
The same conclusion may also be deduced
from the circumstance that women have a ,
smaller proportion of red particles than men, s
the difference having been shewn by M. Le-

canu to be attributable to the monthly loss

which they habitually experience. Besides

change of colour,to which the red particles are

liable during disease, and which, among other

Causes, may arise from an altered proportion in

the saline matters contained in the blood, they

also appear to undergo structural alterations.

Tn fevers, in malignant diseases, in sea-scurvy, in

cases of poisoning, and of asphyxia from light-

ning, a permanently liquid state of the blood

occurs, wherein the colouring matter of the

globules appears to have lost its character of

insolubility in the serum, and to be capable of

percolating those tissues which are otherwise

destined to contain it. Passive hemorrhages,

petechie, and ecchymoses, are the results during

life; and, after death, a stained condition of the

lining membrane of the heart, the arteries, and

veins, which has often been mistaken for vas-

cular congestion of these parts.

The oil or unctuous soft solid which is now
ascertained to be one of the constituents of
healthy blood,* is liable to morbid increase
under various forms of disease. Morgagni cites
two cases of malignant fever in which the serum _
was milky. Hewson, besides enumerating in-
stances to be met with in authors, gives three
cases sent him by medical friends: one of
amenorrhea with dyspepsia and vicarious dis-

violent and continued epistaxis, and a third of —
dyspepsia with slight asthma. In all three cases _
there were symptoms of plethora; but milky
serum is by no means necessarily con 14
with this state. The most marked instance that —
I have met with was in a case of diabetes, where
bleeding was several times repeated at long in- _
tervals, and on each occasion the same morbid 5

Ao

* Med,-Chir. Trans. vol. xvi. p. 46.

t

BLOOD, MORBID CONDITIONS OF THE. 423

condition of serum was observed. This was quite
Opaque, and nearly as white as milk; and on
Standing for a few hours, a film of mattter re-
sembling cream covered the surface. The clot
could not be seen when it was scarcely a tenth
of an inch beneath the surface. It had a
firm, very thick, white coat of fibrine, and the
red particles were almost diffluent beneath.
The patient, a female, could not be called ple-
thoric, having been the subject of her emaci-
ating complaint more than a year and a half.
Milky serum, though of a far less marked cha-
racter, having occurred in persons who have
been bled shortly after making a hearty meal,
the notion has been entertained that it is owing
to the passage of liquid chyle into the circu-
lation. This was Haller’s opinion, while others
have attributed its appearance to admixture of
fat. To the former notion it may be objected,
that whereas it is certain that the milky appear-
ance of serum is owing to the presence of oily
particles, it is very doubtful, from the discord-
ant opinions of eminent chemists, whether the
chyle contains more oily matter than the blood
itself. Berzelius, indeed, makes its solid part
to consist of more than twenty-one per cent. of
fat, and Raspail considers it as differing little
from milk. Prout, however, whose analysis is
adopted by Turner, only admits an unappre-
ciable trace of oily matter in chyle, and makes
its composition differ little from blood ex-
cept as respects the absence of red particles.
In milky serum the oil exists in superabun-
dance at the expense of the albumen, which, in
all the specimens I have examined, has been
remarkably deficient in proportion, its specific
gravity varying from 1:019 to 1:024. This cir-
cumstance naturally leads to a question whether
this oil may not owe its origin to some chemical
change in the albumen itself, of which it seems
to supply the place. The ‘remarkable blood’
described by M. Caventou,* and alluded to by
M. Raspail,+ which was evidently nothing
more than blood with milky serum, affords ad-
ditional ground for supposing that such a
change takes place. “ This blood issuing from
the vein was turbid, of a pale dirty red colour,
and became marled and of a whitish red as it
cooled in the basin, and some drops which fell
on the floor assumed this colour in a few
seconds, and looked like drops of chocolate
made with milk. After half an hour a coagulum
of moderate size was formed in it, which floated
in a large quantity of a white opaque fluid ex-
actly like milk.” Raspail, who had evidently
never seen a marked example of milky blood,
gives the following fanciful explanation of the
appearance. “ Under the influence, or in the
nce of one of the causes which together
— the circulation, an acid had been
med, which, saturating the alkaline men-
struum of the albumen, had caused it to coagu-
late. Now this irregular coagulation could not
take place without disguising the colour of the
blood and rendering it rose-coloured, while it
would give the serum the appearance of milk.”
If the albumen had really been coagulated by

* Annales de Chimie, vol. xxxix. p. 288.
t Sect, 941,

an acid,a distinct clot would not have been
formed by it, but a curdled precipitate; nor
would the serum have borne any resemblance
to milk. But what is important as confirming
my view respecting the conversion mentioned
above, M. Caventou, to his great astonishment,
could not find any albumen in the milky serum
here described. The probability of this change
is heightened. by the consideration that some-
thing analogous must necessarily occur in the
formation of true milk, the oil of which, when
separated as butter and melted to clarify it
from curd, remarkably resembles the oil of
milky serum.

The attention of pathologists to the salts of
the blood, which, considering the visible effects
they produce on this fluid, had been strangely
neglected, has of late years been roused by the
observations of Dr. Stevens, who certainly may
claim the merit of having advanced our know-
ledge of facts on this subject. It appears that
in the last stages of tropical fevers the saline
ingredients of the blood are so much diminished
that they are no longer capable of giving a red
colour to the hematosine. The black blood
that is found in the heart after death from
either the climate fever or the African typhus,
remains black even in an atmosphere of pure
oxygen, but it instantly changes colour when we
add it toa clear fluid that contains even a small
portion of any neutral salt. Nor is it in fever
alone that this deficiency of salts is observed.
Dr. O’Shaughnessy has shewn that it likewise
exists in malignant cholera, and it is probable
that in sea-scurvy, and in those analogous dis-
eases produced by want and unwholesome
nourishment, a similar state occurs.

The saline matters may be in excess as well
as in defect, and this is marked by excitement
of the circulating system, and either local de-
terminations or general febrile disturbance. The
stimulant effect of saline springs has been known
time out of mind, while the thirst and heat pro-
duced by the too copious use of common salt
is in every body’s experience. If we couple
these facts with the certainty that the neutral
salts will pass unchanged through the circu-
lation so as to admit of detection in the urine,
we may infer that their superabundance in the
bood is not only a possible, but, in all proba-
bility, a frequent occurrence. They are occa-
sionally found after death deposited in a crys-
talized form, as was observed by Sir Everard
Home, who, in dissecting an aneurismal tumour,
found a mass of crystals, which were analyzed
by Mr. Faraday, and are stated to have been
salts usually met with in the blood.

Having thus concluded such remarks as the
present state of our knowledge has enabled me
to offer respecting the morbid changes which
take place in the separate constituents of the
blood, I now proceed to notice some of the
more important diseases in which those changes
have been observed to occur.

Inflammation.—The usual appearances of
blood in inflammatory diseases have already
been described in treating of the buffed coat.
The crassamentum is commonly supposed to
be increased in bulk, but this is somewhat
doubtful; and indeed itso much depends upon

424

extraneous circumstances, such as the form of
the vessel in which the blood is received, the
time allowed for the contraction of the clot,
which it is well known goes on for many hours,
and even the quantity abstracted, that no accu-
rate deduction can be drawn from its appear-
ance. The collection of the fibrine itself is
easily effected, and it will thus be perceived
that, under inflammation, it is more abundant
than in the normal state. Scudamore has made
numerous experiments on the relative quantity of
fibrine contained in healthy and diseased cras-
samentum, and the following short list selected
from them satisfactorily establishes this fact.
In 1000 grs. of clot as deduced from

eight specimens of healthy blood,

average of dry fibrine.......... 3°53 grs.
Maximum 4°43, minimuin 2°37

Slight pleurisy, blood slightly buffed 7-05
Pain in the side, dittos seo" IP3F
COUR CON od Rate CI ee Rowen he ee
Acute gout, blood not buffed, firm

SOKCUTE | ie ee ess welteeceess) OOO
Disease not named, clot compact,

buffed, and cupped .......... 12°41
BINDS oS eo PSE Wire oe wa Plame eed Naren
BHT 6b Pi die SHEN Sake et Oe

Mr. Jennings, in his report on the blood in
the Transactions of the Provincial Medical As-
sociation for 1834, likewise gives a table, the
result of which is, that in eight cases of in-
flammation, the proportion of fibrine in the
blood was increased from 2°1, which is Le-
canu’s standard of health, to 9, 8, 11, 6, 5°3,
7, 6°9, 7; average 7°525, and that the alkaline
salts were diminished from 8°37, the healthy
standard, to 4°9, 4°8, 5°1, 4°3, 4°2, 4:4, 4, 5°6;
average 4°61.

Among all the varieties of inflammation it is
in acute rheumatism where we find the blood
most decidedly loaded with fibrine. Owing to
the powerful action of the heart and arteries, it
is intensely arterial in character, and sometimes
issues from the vein with a distinct pulsation.

Fever.—In those. fevers which arise from
marsh miasmata or from contagion, it is an
opinion held by Dr. Stevens, and supported at
great length in his work on the blood, that a
diseased condition of that fluid is the first in
the train of symptoms which occur, and the
immediate cause of those which follow. The
blood itself, says Dr. Stevens, is both black
and diseased even before the attack. During
the cold stage it is very dark. When first
drawn it has a peculiar smell, and coagulates
almost invariably without any crust. There are
black spots on the surface of the crassamentum,
the coagulum is so soft that it can easily be
separated by the fingers, and during its forma-
tion a large quantity of the black colouring
matter falls to the bottom of the cup. In the
hot stage it becomes more red, and, in some
cases, it is even florid for a time, but during the
remission it is darker in colour than the blood
of health, and decidedly diseased in all its
properties. In milder cases, the blood which
is drawn may coagulate without a crust on the
surface ; but in the more severe forms of this
fever, when the blood was drawn at an advanced
period of the disease, a part of the albumen

BLOOD, MORBID CONDITIONS OF THE.

coagulated on the surface of the fib:
formed a diseased mass, which in appe
had a greater resemblance to oatmeal ¢
than to blood drawn from a healthy pers
The serum which separated was also disea
it had a brownish colour, and in some case
an oily appearance, which is never met with
in the clear serum of healthy blood. In
the climate or seasoning fever of the West —
Indies, which is not considered contagious, but
a fever of excitement, the blood drawn in the
first stage flows from the vein with great force,
but is neither cupped nor buffed. It is so florid,
being charged with salts which ought to have
been removed by the organs of secretion, that
it resembles arterial blood. The fibrine coagu-
lates firmly, and in some cases the serum which
separates from it has a bright arterial colour,
the colouring matter being not merely diffused
through, but combined with the serum. During
the progress of this kind of fever the blood loses
a large proportion of its fibrine and albumen,
and becomes so thin that it oozes from the mu-
cous membranes without any abrasion of sur-
face, and in the last stage turns quite black from
a diminution in the proportion of its salts.

Such are the appearances which the blood
presents in the more severe fevers of hot cli-
mates. In this country, at the commencement
or stage of depression the blood is dark and
tarry, coagulates quickly, and forms a large
clot with but little serum. As the stage of
excitement advances, the blood becomes thinner
and more florid, and flows more freely. Coa-
gulation takes place more slowly, and a buffy
crust is frequently formed on the surface of the
clot. In the latter stage, when the powers
are giving way, the blood becomes thinner,
darker, and more dissolved. It scarcely coa-
gulates at all, and is deficient in saline matter,
and probably also in fibrine, thus nearly re-
sembling menstrual blood, or the fluid mixture
of serum and red particles, already mentioned
as often found in the larger vessels after death.
Such are the alterations which the blood usually
undergoes in the different stages of simple con-
tinued fever, but in its more malignant forms, as
in typhus, the blood is generally very watery,
even from the commencement. As the disease
advances, it gradually loses its power of coagu-
lation, and in the last stage seems almost en-
tirely deprived of fibrine.

Magendie has artificially produced an analo-
gous state of blood by injecting putrid liquids
into the veins of animals, and the speedily fatal
disease which he thus caused had a strong ana-
logy with typhous fever.* ne

To Dr. Stevens belongs the merit of having
especially directed general attention to the cir-
cumstance that the saline matter of the blood ~
gradually disappears in the progress of fever,
and is almost entirely lost in its last stage.
This he ascertained by direct experiment,f —
and his facts have since been confirmed by —
Jennings, who in the interesting report already
alluded to, gives an analysis of the oes 9a
in six cases of continued fever, in which the

Tang <i
oe

a
‘on?

* Sournal de Physiologie, tom. iii. p. 83.
t On the Blood, &c. page 209,

BLOOD, MORBID CONDITIONS OF THE.

alkaline salts were found diminished in the fol-.

lowing proportions :—
In healthy serum, according to Lecanu,
In the serum of a male, aged 31, first day
of fever, salts ...+...- eeeeee
Ditto ditto aged 34, first day
Of fever, Salts... .ssc,sceesee cveees O
Ditto female, aged 14, fourth
day of fever, salts . we vewecses 42
Average of three other cases .... 4:4
Scurvy.—It seems to be the universal opi-
nion of those who have seen and written on
seurvy, that it owes its origin to a morbid
_ change in the fluids, and especially in the
blood; and even those who have been the most
strenuous opposers of the humoral pathology
in general, among the most celebrated of whom
we may reckon Willis, Hoffmann, Boerhaave,
Cullen, and Sir John Pringle, have made an
exception in favour of this disease. Notwith-
standing this general belief there has been no
attempt up to the present time at any chemical
examination of the properties of scorbutic
blood, and we have only the general obser-
vation made by the surgeons of Lord Anson’s
expedition, (Messrs. Ettrick and Allen,) that in
the beginning of the disease it flows from the
arm in different shades of light and dark
streaks ; that as this advances, it runs thin and
black, and after standing turns thick and of a
dark muddy colour, the surface in many places
being of a greenish hue, without any regular
separation of its parts; that m the third de-
gree of the disease it is as black as ink, ‘and
though kept stirring in the vessel for many
hours, its fibrous parts have only the appear-
ance of wool or hair floating in a muddy sub-
stance; and that in dissected bodies the blood
in the veins is so fluid that by cutting any con-
siderable branch, the part to which it belongs
may be emptied of its black and yellow liquor,
the extravasated blood being precisely of the
same kind. The prevalence of scurvy where
there has been a long-continued use of salted
provisions has given rise to the supposition*
that the salt itself actually finds its way into
the circulation, and acts as it is known to act
on blood out of the body by preventing its
coagulation. This, however, is very evidently
not the case, first, because salt provisions are
not necessary to its production, since scurvy
has often made its appearance where no salt
rovisions were used; as, for instance, in the
ilbank Penitentiary in 1619, where the diet
consisted of pease, barley soup, and brown
bread ; and, secondly, because the appearance
of the blood, especially as the disease ad-
vances, is exactly the reverse of what it would
be on the addition of salt, which, instead of
making it black, and causing it on standing
to become thick, muddy, and of a greenish
hue, would impart to it a fine scarlet tint that
would remain permanent until it began to
putrefy. Since the modern advances in ani-
mal chemistry, opportunities for examining the
blood in true scurvy have been very rare; and

eseserveoeeoeeeeeeeerene ee 8°10

4

eeeeee

* Jennins’s Report,

425

it is therefore the more to be regretted that
Drs. Latham and Roget, philosophers every way
so competent to determine the precise morbid
changes which it undergoes, did not, when they
had it in their power, make a particular ex-
amination of it. Venesection, it seems, was
practised at the Penitentiary in a few cases,
but nothing is stated respecting the appearance
which the blood assumed.* The description
of Lord Anson’s surgeons does not by any
means apply to the blood which is found in
purpura hemorrhagica, a complaint that was,
prior to the appearance of Dr. Bateman’s work
on diseases of the skin, generally considered
closely allied to scurvy. In two cases of pur-
pura related by Dr. Parry,+ of Bath, blood
drawn. from the arm exhibited a tenacious
contracted coagulum covered with a thick coat
of lymph ; and in one instance which occurred
under my care, where the patient, a man of
forty-five years of age, had most of the sym-
ptoms of sea-scurvy, such as general cachexia,
with anasarca of the lower limbs, great depres-
sion of spirits and prostration of strength, ex-
tensive ecchymosis on the trunk and the ex-
tremities, fetid breath and extravasations of
blood from the gums, the stomach, and the
bowels, as well as from a large foul ulcer on
the leg; a copious venesection demonstrated
that the blood had not in any degree lost its
crasis, the crassamentum being covered with a
thick buffy coat, and having as much firmness
as is usual under the existence of such a state.
It is proper to observe that Lind’s description
of the blood in scurvy differs from that of Lord
Anson’s surgeons, as he found it generally either
natural or buffed.

Jaundice.— In jaundice the blood, both
arterial and venous, is tinged with bile, and
this is apparent not only in the serum,
but still more strikingly in the crassamentum,
peeeaes it be covered with a buffed surface.

f this be removed and dried in a state
of tension, it exhibits a deep yellow hue,
particularly when viewed. by transmitted light.
Although the bile is thus rendered very
visible in jaundiced blood, yet, owing to its
combination with albumen, which defends it
from the action of acids, it is difficult of de-
tection by chemical re-agents, so that many
chemists of eminence have sought in vain to
ascertain its presence. Lassaigne, however,
succeeded in demonstrating that the colouring
matter of the bile is really to be found in the
circulation, and Berzelius tells us that Collard
and Martigny pretend to have discovered even
the resin of bile in jaundiced blood. M. Le-
canu has more recently confirmed these facts,
and Mr. Kane has verified his results.¢ To
the medical inquirer who does not follow the

“minutie of animal chemistry, the identity of
the colouring matter in the serum of jaundiced

* Account of the Disease lately prevalent at the
Soeorhl Penitentiary, by P.M, Latham,M.D. 1823,
p. 39.

+ Edinburgh Medical and Surgical Journal,
vol. v. p. 7.

{ Lind on Scurvy, page 512.

§ Dublin Journal, vol. ii. p. 346.

426

blood with that of the bile itself will be ren-
dered sufficiently evident by adding to it an
equal quantity of sulphuric acid diluted with
twice its bulk of water. Tle serum will thus
- change its yellow hue for the characteristic
green colour of acid bile. Experimentalists
have failed in producing this effect, being pro-
bably misled by having found that the small
proportion of acid which is required to strike
a green colour with urine charged with bile,
produces no such effect when added to jaun-
diced serum.

Disease of the kidney—tIn those organic
diseases of the kidney which are characterized
by anasarca and the passing of urine coagu-
lable by heat and acids, the albumen of the
blood is more or less deficient in proportion;
and this is marked by a corresponding dimi-
nution in the specific gravity of the serum.
. In a letter to Dr. Bright, published in the first
volume of that author’s Reports of Medical
Cases, page 83, Dr. Bostock states, in re-
ference to the blood in these diseases, that
the crassamentum was for the most part co-
vered with a thick buffy coat, and was gene-
rally of a firm consistence. The appearance
of the serum was more varied. It was occa-
sionally turbid, and upon standing for twenty-
four hours a white creamy substance rose to
the surface; but no proper oily matter could
be detected in it. On exposing it to heat, it
coagulated in the ordinary manner, except that
the coagulum seemed to contain an unusual
number of cells, and that a greater quantity
of serosity separated from it. ‘I think I may
venture to say,” adds the writer, “ that the
serum generally in these cases contained less
albumen than in health, although I am not
able to state precisely the amount of this dif-
ference. The serosity which drained from the
coagulated albumen on being evaporated was
found to consist in part of an animal matter
possessing peculiar properties which seemed
to approach to those of urea; it was partially
soluble in alcohol, and was acted upon ina
somewhat similar manner by nitric acid.”

The above remarks were made on specimens
of blood furnished from time to time by Dr.
Bright. The number is not stated, nor was the
specific gravity of the serum taken. Dr. Bos-
tock gives a case, however, (page 85,) where,
after stating that the crassamentum was re-
markably buffed and cupped, he adds, “ The
serum was also worthy of attention, as taken
in connexion with the state of the other fluids.
Its specific gravity was almost exactly the same
with that of the urine, being no more than
1:013, which I believe to be lower than had
ever occurred to me in the numerous expe-
riments which I have made upon this sub-
stance. We have here, therefore, an example
of blood exhibiting a very great deficiency of
albumen, at the same time that we observe the
mode in which it passes off from the system
by means of the kidney, while this organ has
its appropriate office of secreting urea nearly
suspended. I regret that I did not attend
particularly to the specific gravity of the other

specimens of dropsical serum which you sent

BLOOD, MORBID CONDITIONS OF THE.

me. From sortie incidental erm
notes, I suspect that its specific gravity c
have been found lower than ordinary; but it
is a circumstance which I shall be anxious to
ascertain when any opportunity occurs.” This
suspicion is completely confirmed by other
cases that have occurred to myself, in which
the fact was also established beyond doubt, —
that the animal matter found by Dr. Bostock
in the serosity was not merely an approach to
urea, but that principle itself possessing all its
usual characters. ‘The following may serve as
an example of light serum.

William Squires, aged 54, labouring under or-
ganic disease of the kidneys and chronic bron-
chites with anasarca, had for many months
voided urine which coagulated on the appli-
cation of heat or the addition of nitric acid.

The specific gravity of his blood at

88 Fahr. was 1°041

Do. Serum at 68 1021
healthy standard 1-030.

This blood contained in 1000 parts,

3°845 fibrine :
healthy standard 2°1 to 3°56
55°000 albumen :
healthy standard 65 to 69
In this case 100 grains of urine contained 6-666
albumen. There was consequently nearly one
eighth as much albumen in the urine as in the
blood, and the patient lost as much of that con-
stituent daily, as if he had been bled to the
extent of four ounces.

The following cases are from notes with which
I have been favoured by Dr. G. H. Barlow,
who has devoted much attention to the exami-
nation of the blood and urine in this disease. -

No.1. A patient affected with general ana-
sarca—Urine copious, clear, pale, coagulable
by heat and nitri¢ acid : specific gravity 1-011.
Blood cupped and buffed, serum milky: spe-
cific gravity 1:019.

No. 2. Man aged 48, anasarcous—Urine
dingy brown, natural in quantity, acid, coagula-
ble; specific gravity 1017, contained 41 per
cent. of albumen. Serum of the blood, specific
gravity 1°013.

No. 3. A man who was found on post-mor-
tem examination to have granulated kidneys.
Urine reddish brown, very scanty, coagulable ;
specific gravity 1:008. Blood cupped and buf-
fed ; specific gravity (of the whole blood) 1:037.

In my paper on the blood in the Medico-
Chirurgical Transactions, vol. xvi. I have stated
the case of a woman forty-eight years of age, who
for ten weeks had complained of pains in her
loins, anasarcous swelling of her legs, and. ge-
neral debility, and who passed urine which was
in a high degree coagulable. I examined her
blood, and found it to contain 0°43 percent. of
fibrine, and only 1:61 per cent. of albumen.
The specific gravity of the serum was 1°020 —
at 60° Fahr. In that paper I have also ©
observed that in several cases marked
coagulable urine, I have examined the specific —
gravity of serum with which Dr: Bright has fur-
nished me, and have always found it much
below the healthy standard.

It is not, however, in this complaint ex-

;
]

a ee

i

\

oJ

BLOOD, MORBID CONDITIONS OF THE. 427

clusively that the albumen of the blood will
be found deficient in proportion. In other
dropsical affections it will sometimes happen
that a proportion of albumen more than equi-
valent to the fibrine effused will disappear
from the circulation. Eleven days after tap-
ping a young woman, in whom ascites had
supervened upon rheumatic affection of the
heart, she was observed to be filling again very
fast. A few ounces of blood were taken from
the arm, and this blood was found to contain

0°319 per cent. of fibrine, and only 3°51 per
cent.of albumen. Her serum had a specific
gravity of 1-023.

_ The experiments of MM. Prevost and Dumas
(Annales de Chimie, vol. xxiii.) which have
since been repeated by Gmelin and Tiedemann
(Poggendorff’s Annalen), prove satisfactorily
that urea exists in the blood after the kidneys
have been extirpated, and consequently that it
is not formed, but merely abstracted by those
organs. So long, however, as the kidneys act,
we cannot expect to find it, since it is removed
from the circulation as fast as it is formed, and
never exists in any considerable quantity.

In these cases of diseased kidney a result
analogous to that which follows extirpation
occurs, for while that organ is permitting albu-
men to pass through it unchanged, the urea
which it should separate is very generally if not
always found in the blood. This I have proved
in repeated instances, and it is now so generally
admitted from the experiments of Prout, Chris-
tison, and others, that it is scarcely worth while
to cite cases. Dr. Bright, vol. ii. p. 447, al-
ludes to several specimens of serum from
patients under this disease, which he had sent
me for examination, in some of which I did,
and in others I could not detect urea. In one
very remarkable instance of a young woman, the
albuminous state of whose urine constantly
existed for above three years, the urine con-
tained less than one-third of the normal pro-
portion of urea, while about one per cent. of
albumen supplied the deficiency. The serum
of the blood was, as I have already remarked to
be usual in this disease, of very low specific
gravity, being only 1°021. The quantity of al-
bumen in 1000 grains amounted, after careful
drying, to only 50 grains instead of 78 (Le-
canu’s healthy standard), and it contained fully
as much urea as the urine itself, the 1000 grains
yielding nearly 15 grains of that principle.

It may not be out of place here to observe,
that in this disease not only does the blood it-
self contain urea, but all those effusions also
which are formed from it, and which take place
in the different serous cavities. I have repeat-
edly detected urea in these cases in the serous
effusion into the ventricles of the brain; and
Dr. Barlow found it in one case, 1st, in abun-
dance in the ventricles of the brain; 2dly,
scantily in the effusion into the pleura and peri-
cardium ; and 3dly, in jabundance in the peri-
toneum. Ina second case ofa similar nature
urea was obtained in abundance from the fluid
of the pericardium. In a third the effusion
collected after death from the pleura of a man
who had suffered from general dropsy and mot-

tled kidney, yielded a very satisfactory specimen
of urea.

I have dwelt at some length on this subject,
as it is only of late years that the attention of
the medical world has been drawn to it through
the writings of Dr. Bright, and still more re-
cently that the morbid changes presented in the
blood have been investigated.

Diabetes.—In this complaint the blood un-
questionably undergoes some material change,
although its nature has not hitherto been very
successfully investigated. This may be inferred
from the great length of time during which it is
capable of resisting putrefaction, a circumstance
first noticed by Rollo, and which, though
doubted by some authors, I have had oppor-
tunities of confirming in several instances.
Nicolas and Gieudeville* have observed that it
contains an increase of serum and very little
fibrine, but this is not borne out by my own.
experience as deduced from many specimens of
diabetic blood which I have examined ; neither
can its antiseptic qualities be attributed to any
deficiency in the proportion of azote, for Dr.
Prout, who has made accurate experiments to
determine this point, has found it not to differ
in this respect from the standard of health.
The most eminent chemists both abroad and in
this country have endeavoured in vain to de-
tect sugar in diabetic blood. Dr. Wollaston
ascertained that the smallest portion of saccha-
rine matter added to serum previously to its
coagulation by heat, prevents the subsequent
crystallization of the salts it contains, yet that
in diabetic serum those salts crystallized with
the same facility as in that procured from a
person in health. The same reasoning as that
which has been adduced to prove that urea may
be formed in the blood, although it is not to be
detected there while the kidneys perform their
office, will also apply to the existence of sugar
in the blood of those affected with this disease.
I am not aware that the arterial blood has been
made the subject of experiment, and yet it is
possible that it might exist in the arteries alone,
for we have only to suppose it to enter the cir-
culation with the chyle, and after having been
carried through the lungs, the left cavities of the
heart, and the aorta, to be again withdrawn from
the circulation by the kidneys. I do not pre-
tend, however, that this supposition carries with
it any degree of probability.

Cholera.—There is no disease in which the
blood undergoes more remarkable changes than
in malignant cholera; not indeed in the in-
cipient stage, as affirmed by Dr. Stevens, but in
direct proportion to the intensity and duration
of the collapse. In appearance it is thick and
dark, bearing a strong resemblance to treacle or
tar. It is of high specific gravity, the serum
varying from 1:040 to 1:045 at 60 Fahr.; and
according to M. Lecanu, the solid matter which
it contains is sometimes double that of the
healthy proportion. Most of its physical cha-
racters are satisfactorily accounted for by its
analysis, which has been accurately made by
several eminent chemists, among whom we may

* Annales de Chimie, vol. xliv. p. 69.

428

mention Dr. Turner, M. Lecanu, and Dr.
O'Shaughnessy. Cholera blood, according to
these authorities, contains less water and more
albumen and hzmatosine than healthy blood,
and its salts are in unusually small quantity, or
almost entirely wanting. Dr. O’Shaughnessy,
who has detected urea in cholera blood, states
that the summary of his experiments denotes a
great but variable deficiency of water in the
blood of four malignant cholera cases; a total
absence of carbonate of soda in two ; its occur-
rence in an almost infinitessimally small propor-
tion in one; and a remarkable diminution of
the other saline ingredients: lastly, the micro-
scopic structure of the blood and its capability
of aeration are shewn to be preserved. The
cause of the dark colour of the blood in cholera
is a point which we are told by Dr. Turner is
by no means decided. Dr. Thomson and Dr.
O'Shaughnessy are at variance on the question
of its susceptibility of arterialization. Dr.
Stevens rather unphilosophically makes its
dark colour to depend primarily on the poi-
sonous cause of contagion, yet attributes it also
to a deficiency in the proportion of saline
matter. It is probably not owing to either of
these causes, but to a defective circulation
through the lungs, from which the blue livid
tint frequently observed over the surface of the
limbs likewise originates. The corresponding
diminution of animal heat gives countenance to
this supposition.

Chlorosis——Among other changes which: oc-
cur in the progress of chlorosis, there is none
more constant than an impoverished condition
of the blood, which is thin, light-coloured, and
weakly coagulable, being deficient in fibrine, and
still more so in the proportion of the red par-
ticles. To the latter cause is to be attributed
the diminished temperature of the surface, to-
gether with the universal pallor and waxy ap-
pearance which those who are the subjects of
this disease generally exhibit. The deficiency
of colour in the catamenia, and the pale stain
which hemorrhages from the nose leave on
linen, are also referable to the same cause.
In aggravated cases, if blood be drawn from the
arm, the crassamentum is observed to be of a
pale rose colour, and small in proportion to the
serum. We have to regret that in this, as in
most other cases of morbid blood, pathologists
have contented themselves with a general ob-
servation of facts without attempting to inves-
tigate them with that degree of precision which
can alone lead to a further advancement of our
knowledge respecting their causes. The only
analyses of chlorotic blood of which I can find
a record are given by Mr. Jenkins in two well-
marked cases of chlorosis ; the one of a girl
aged fifteen, the other of a young woman aged
twenty-one. In these the blood contained 871
and 852 parts in a thousand, of water, respec-
tively, instead of 780, the healthy standard ; and
the colouring matter amounted to 48°7 and 52,
instead of 133. The albumen and salts were in
the usual proportions.

Melanosis.—A\though it would be foreign to
my present object to treat of the various morbid
products which may be supposed to have their

result of an accidental change in that fluid,
it must not be passed over without a bri
notice. The similarity of chemical eee
in the blood and in the matter of melanosis is)
such as to leave little doubt that the material
of which the latter is composed has its origin —
in the circulation, and is afterwards deposited
in the various parts in which it is found. The
different analyses of melanosis, says Andral,
all concur in one important point. They all
shew that the accidental production called
melanosis is formed of the different elements
of blood, and especially of a colouring matter
which more or less resembles that of the blood,
but which is, nevertheless, not identical with
it. M. Foy, in his analysis, calls this altered
cruor. Dr. Carswell, to whom we owe the
most detailed and best account of melanosis
which we possess, states that he has fixed its.
seat in the blood, not only because it is seen
there, but because his anatomical researches
shew that it is there formed. He makes a
grand division of melanosis into true and
spurious; the former of which occasionally
makes its appearance in the circulating system,
a fact which is well established, while the
latter is more decidedly the result of chemical
action. Whenever healthy blood comes in
contact with an acid, whether in or out of the
body, its colour changes from red to brown or
black, in proportion to the strength and abund-
ance of the acid employed. It is to this cause
that we are to attribute the appearance of brown
or black ramifications, patches, or points, as ob-
served after death in the stomach and intestines.
To this cause also are owing the accumulations,
during life, of black pitchy matters in the ali-
mentary canal, and it is by the acidity of the
black vomit and its power of reddening litmus
paper, as we learn from Dr. Stevens, that it
can alone be distinguished from blood rendered
black by defective decarbonization or the ab-
sence of saline ingredients. Where a hemor-
rhage occurs, whether by the rupture of a large
vessel or by a general oozing from the mucous
membrane into the stomach or bowels, we shall
find the fluid ejected assume the appearance of
red blood or of brown or black matter, accord-
ing to the presence or absence of the gastric
juice in an acid state. Upon this almost acci-
dental circumstance, then, will it depend whether
we are to designate the disease heematemesis or
melena, there being in reality no essential dif-
ference between the two diseases. The black
discolouration of blood which occurs whenever
it becomes stagnant from retarded or interrupted
circulation, will, by those who follow the views
of Dr. Stevens, be attributed to a similar cause.
According to that author it is the presence of ©

re

carbonic acid which acts like other acids in ren-
dering venous blood dark, and it is its abstrac-
tion by oxygen which, combined with the action _
of the saline matters it contains, restores it to
its scarlet hue. ee

The foregoing are among the more pro- —
minent diseases in which the blood has been
observed to undergo changes either directly

“ 2

BLOOD, MORBID CONDITIONS OF THE. 429

cognizable by our senses, or discoverable b
those chemical and mechanical means which
we are enabled to call to our assistance. There
are, however, other morbid conditions the ex-
istence of which is equally certain, although
their essence is of such a doubtful nature that
it defies detection by the coarse instruments
and the limited skill which man, in the present
state of his knowledge, is enabled to employ.
In the exanthematous diseases the blood par-
takes of the general disorder of the system. Dr.
Home of Edinburgh* succeeded in reproducing
measles by inoculation with blood drawn from
a superficial vein in one of the patches of
es gee which cover the skin in that disorder ;
and though others have failed in this experi-
ment, it has been successfully and often re-
peated by Professor Speranza of Mantua.
Pregnant females affected with small-pox, or
even exposed to its virus, though they may
have had the disease, have often imparted it to
the fetus in utero,t and syphilis has been
communicated in the same manner. Professor
Coleman has proved by experiment that the
blood of a glandered horse will impart glan-
ders if infused into the veins of a healthy
animal. Dupuy and Leuret have thus pro-
duced malignant pustule; transfusion of the
blood of a mangy dog has produced mange in
another; and, according to Dr. Hertwich of
Berlin, the blood of a rabid animal will by inocu-
lation communicate the disease. A remarkable
instance is related by Duhamel, in which a
butcher became affected with a malignant pus-
tular disease in consequence of having put into
his mouth the knife with which he had slaugh-
tered an over-driven ox. Another individual
lost his life from sphacelus of the arm in con-
sequence of a wound in the palm of his hand,
accidentally inflicted by a bone of the same
animal; and in two women who received some
drops of its blood, the one on her hand, the
other on her check, inflammations ensued which
rapidly terminated in gangrene.

_ Although in all these instances there can be

~no doubt that the blood was in a poisonous

State, there is no reason to suppose that this
could have been foretold by any thing remark-
able in its appearance or sensible qualities.

ly more successful in general has been
the search for extraneous poisons, which never-
theless have appeared from collateral circum-
stances to have entered the circulation, or have
even been purposely introduced into it. Dr.Chris-
tisont has cited a sufficient number of cases
where poisons swallowed have been afterwards
found in the blood, to shew that we must not
infer their absence from our inability in most
cases to abstract them in a separate form; and
he further demonstrates how erroneous such an
inference might be by stating that Dr. Coindet
and himself, after destroying a dog in thirty
seconds by injecting 83 grains of oxalic acid
into the femoral vein, endeavoured in vain to

* Duncan’s Medical Commentaries, vol. xix.
p- 213. ;

+ Edinb. Med. and Surg. Journ. for April 1807.
Med.-Chir. Trans. vol. i. p. 272.

¢ Christison on Poisons, p. 14.

detect any portion of it in the blood of the itiac
vein and vena cava collected immediately after
death, although it is highly improbable that it
could have passed off by any of the secretions
in so short a time.

The chief obstacles by which we are opposed
in such researches are minuteness of quantity.
and decomposition. When only a few grains
of a poison are absorbed, and thence diffused
not only through the whole mass of circulating
blood, but likewise among all the various
tissues and solids of the body, being moreover
carried off by the kidneys, perhaps nearly as
fast as they enter by the circulation, it cannot
be matter of surprise, however delicate our
tests may be, that they are seldom to be met
with even where still retaining their chemical
characters. When we consider, however, that
reagents which produce a change of properties
in those bodies with which they are brought in
contact do probably themselves undergo a cor-
responding change, we shall readily perceive
that our difficulties will be still further in-
creased on this account.

The products of diseased action, and espe-
cially pus, have been often met with, as well in
the arteries and veins, as in the cavities of the
heart ; but it yet remains a matter of doubt
whether these are actually formed in the blood,
or whether, as seems to me more probable,
they are not rather carried into the circulation
from other parts in a degenerate or diseased
State, or are the products of inflammation in
the lining membrane of the bloodvessels them-
selves.

With respect to those cases where worms
and insects are said to have appeared in the
blood, whereof many are recorded, some are
referrible to the head of false polypi, the shape
of which has misled the observer, others to
deception or the accidental presence of insects
or their ova in the receiving vessel ; and though
we cannot deny the possibility that parasitical
animals may exist in the fluids as well as in the
closed cavities and solids of the body, yet we
require better evidence than has yet been ad-
duced to confirm our belief in the existence of
entozoa in the circulating current. In a recent
case brought forward by Mr. Bushnan,* and
learnedly illustrated by that gentleman, it
would, I confess, have carried more conviction
to my mind, had he himself watched the blood
from the moment of its quitting the vein until
the larvee which he describes were seen swim-
ming in itsserum. In such extraordinary cases
the mind is not satisfied with anything short
of moral certainty.

From what has been set forth in the fore-
going pages, it will be perceived that our
knowledge on the subject discussed in them
yet remains extremely defective. We learn,
indeed, that under the existence of disease
the different constituents of the blood are
liable to morbid increase or diminution as well
as to certain alterations in their sensible qua-
lities, hitherto less accurately examined ; that

* History of a case in which animals were found
in blood, &c.

430 BONE, NORMAL ANATOMY.

there are instances in which principles not
usually met with in the healthy circulation may
be detected in it, and others where those which
are always present in a state of health do nearly
if not altogether disappear. But that which
still remains unknown, and to which it is of
the highest interest and importance that our
investigations should be directed, is the con-
nexion that these morbid changes have with the
diseases which they accompany ; the position
which they occupy in the relation between cause
and effect. Perhaps our present information
is not sufficiently minute to give fair expecta-
tions of any considerable advances being made
in this line of inquiry ; for when we contemplate
the variety of materials for the formation and
removal of morbid as well as of healthy secre-
tions and structures, which are stealing unper-
ceived along the vital current, we are forced to
confess how small is the sum of all we know
compared with that of which we are still igno-
rant, and how ample is the harvest which yet
remains to be gathered by future labourers in
this field of research.

BiBLIOGRAPHY.—( The following comprehends the
most esteemed writings on the blood in its healthy as
well as its morbid states.)—R. Boyle, Mem. for a
nat. hist. of human blood, 8vo. Lond. 1684, and
Analytical observ. on milk found in veins instead
of blood, Phil, Trans. 1665. Albinus, De Masse
Sanguinis corpusculis, 4to. 1688 (Recus. in Haller
Disp. Anat. t. ii.) ; Ejus, De Pravitate Sanguinis,
4to. Franc. 1689. De Sandris, De naturali et preter-
naturali sanguinis statu, 4to. Bon. 1696. De Haen,
De sanguine humana, in Ej. Ratione medendi.
N. Davies, Exper. to promote the analysis of the
blood, 8vo. Lond. 1760. Fontana, Nuove osserv.
sopra i globetti rossi del sangue, 8vo. Lucca, 1768.
Hewson, Exper. inquiry into the properties of the
blood, 8vo. Lond. 1771-78. Spallanzani, Fenomeni
della circolazione, 8vo. Moden, 1773; Anglice by
Hall, Lond. 1801. Haller, El. Physiol. t. ii.
Bordeu, Analyse Med, du sang, Par. 1771. Thou-
venel, Mém. sur le méchanisme et les produits de la
sanguification, Mém. de l’Acad. de St. Petersbourg,
an. 1776. Della Torre, Oss. microscopiche, 4to.
Neap, 1776. Hey, Observations on the blood, 8vo.
Lond. 1779. Blumenbach, De vi vitali sanguinis
deneganda, 4to. Gotting. 1788. Deyeur & Par-
mentier, Mém. sur les alterations du sang, 4to. Par.
1797. Hunter on the blood, &c. 1794. Wells on
the colour of the blood, Phil. Trans, 1797. Kreysig,
De sanguine vita destituto, Prag. 4to. 1798. Tollard,
Diss. sur la fibrine, 4to. Strasb. 1803. Le Gallois,
Le sang est il identique dans tous les vaisseaux,
8vo. Par. 1805. Henke, Uber die vitalitat des
Blutes, 8vo. Berl. 1806. Bostock, Med.-Chir. Trans.
vol.i. Dowler on the products of inflammation, Med.
Chir, Trans, vol. xii. Thackrah on the properties
of the blood, 8vo. Lond. 1819. Wilson, Lectures
on the blood, &c. Lond. 1819. Kolk, Sanguinis
coagulantis historia, &c, Diss. Inaug. Groning.
1820. Cotte, Sur les diff. caractéres du sang dans
Vetat de santé et de maladie, 8vo. Aix, 1821. Davy
on the buffy coat, Phil. Trans. 1822. Krimer,
Versuch einer Physiol. des Blutes, 8vo, Leipz. 1823.
Stoker, in Pathological Observations, Dublin, 1823.
Scudamore, Essay on the blood, Lond. 1824. Mi-
chaelis, De partibus constitutivis sing. partium sang,
art. et ven. 8vo. Berol. 1827. Babington on fatty
matter in the blood, Med.-Chir. Trans. vol. xvi.
Christison in Ed. Med. and Surg. Journal, No. ciii.
Velpeau, Recherches sur les altérations du sang,
8vo. Par. 1826. Trousseaux, in Arch. Gén. de
Méd. t. xiv. Segalas, in ibid, t. xii. Gendrin,
Recherches sur les fiévres, and Hist. anat, des
inflammations, Andral, Pathological anatomy,

by Townsend. Denis, Rech. exper. sur le
hum, 1830. Stevens on the pees 8vo. ae .

O’ Shaughnessy, Report on the chemical pathology
of Aa Lond. 1332. Prevost & Dumas, Examen
du sang, &c. Bibliothéq. Univ. de Genev. t. xvii.

See also Rudolphi, Blumenbach, Sprengel, Adelon,

&c. in their systems of physiology. i
( B. G. Babington.)

BONE, (general anatomy in the normal state.)
Gr. ogreov. Lat. os. Fr. os. Germ. der Knochen.
Ital. osso. The important offices fulfilled by
bone in the animal economy, and its almost
imperishable nature, could not but give it im-
portance in the eyes of the philosopher; whilst
every language bears testimony to the high
place it holds in popular estimation. We see
it forming a framework to give shape and sup-
port to the body, cases and cages to protect
the more delicate organs, levers by which loco-
motion is performed and force exerted. Again,
we find it, among the tombs, successfully resist-
ing those destructive agents which a century
before reduced the softer portions of the body
to dust; and we speak of laying our bones in
the grave as if they constituted the essential
element of our frame.

We propose to treat of the general anatomy
of bone under the following heads, viz.—1. its
physical properties and intimate structure in
man: 2. its periosteum and medulla, and its
organization as a part of the living system: 3.
its chemical composition: 4. its peculiarities
in other animals.

1. The physical properties and intimate
structure of bone in man.—The most remark-
able property in bone, and that which first
arrests attention, is its extreme hardness com-
pared with other parts of the system. It is,
indeed, the only substance in the body which
deserves to be called hard; all others are more
or less soft, and are consequently destitute of
that resistance and firmness by which bones
are so admirably adapted for the offices they
have to fulfil in the animal machine. The
hardness usually increases with age. It varies
a little in different situations, and depends, as
we shall see, on the earthy matter which enters
largely into the composition of the bones.

The colour of bone in the living person is
a pale-rose colour, inclining, in early life to
red, m old age to a yellowish white. Bones
assume a beautiful white when macerated and
deprived of the oily and sanguineous fluids
which pervade them. The specific gravity of
fresh bone is greater than that of any other
animal substance. Bone is opaque or only
slightly diaphanous. Bones are flexible and
elastic. We find that the ribs may be bent
and afterwards recover their form perfectly ;
every schoolboy, indeed, knows the value of
ahorse’s rib as a bow. This elasticity frequently
saves them from fractures, and lessens the shock
which would otherwise be communicated
to the nervous centres and delicate structures
they defend. It is possessed by every bone,
and may be demonstrated in the oldest and

most rigid by cutting them into thin slices.

Shape.—Bones assume every variety of shape,

as might be expected from the use made of

—— a os ~~~

—

BONE, NORMAL ANATOMY.

them in so complicated a piece of machinery
as the skeleton. These varieties have been
reduced by anatomists to four classes, viz. 1.
the long or cylindrical ; 2. the broad or flat ;
3. the short or thick ; and 4. the mixed or irre-
gular bones. The long bones are distinguished
by their length, which greatly exceeds their
other dimensions. They are to be found only
in the extremities, and are adapted for locomo-
tion and for supporting the weight of the body.
They are never exactly cylindrical, being al-
ways contracted in the middle or shaft, and
enlarged at each end; and their transverse sec-
tion is oval or. triangular, never round. The
broad or flat bones are thin, generally arched,
and fitted to protect delicate organs; we find
the best specimens of them in the cranium.
The short have nearly equal length, breadth,
and thickness; they are seen in the carpus and
tarsus. The mixed or irregular bones are
usually classed with the short, but it is more
convenient to separate them: the vertebre are
good examples of these. The ribs and bones
of the pelvis may also be ranged with them,
combining the characters of two of the pre-
ceding classes. Each of these divisions exhibits
certain peculiarities of structure to which we
shall allude hereafter.*

If we prepare bones by careful maceration
and drying, and then saw them through, or,
what is better, fracture them with a smart blow
of a hammer, we observe the density of texture

431

to differ very much in different portions. The
outer part is generally much more dense and
close than the interior, and is called the com-
pact, vitreous, or cortical substance. The inte-
rior, open and areolar in its appearance, is the
spongy, cancellated, or reticular substance.
These two are arranged in a peculiar manner
in each class of bone. In the dong there isa
considerable thickness of compact substance in
the shaft, surrounding a cavity, and but little
of the spongy, whilst towards the ends the
compact gradually becomes thin as paper, the
spongy increasing in quantity and filling up all
the interior, as if formed by the expansion of the
compact tissue (fig. 186, a). In the flat bones
the compact substance is formed into two plates
with a thin stratum of spongy substance called
the diploe between (fig. 186, b). In very thin
bones the diploe is often absent. The short
bones are spongy throughout, with a thin layer
of the compact tissue on the surface; they are
like the extremities of the long bones: and the
irregular, resembling in shape two or more of
the former classes, have a corresponding arrange-
ment of the two tissues.

A vertical section of three long bones is re-
presented at fig. 186, where A is the head and
neck of the femur, and B the upper extremities
of the tibia and fibula: a indicates the com-
pact tissue; 6 the reticular; at c it may be seen
how thin is the layer of compact tissue cover-
ing the head of the femur.

Fig. 186.

In the shaft of the long bones there exists a
cavity of considerable size filled with marrow,
and called the medullary cavity. This is widest
in the centre, gradually getting smaller towards

* See further particulars respecting foramina,
processes, epiphyses, &c. as connected with mecha-
nical contrivance, under the article SKELETON,

the extremities, where its place is occupied with
spongy substance. The interior of this cavity
is rough; bony processes project into it, and
form a kind of net-work resembling the spongy
substance at the ends, but with more open and
less regular cells. By some anatomists the
term spongy is confined to the cellular arrange-
ment at the ends, that in the middle being

432

denominated reticular or cancellated, Sucha
distinction is useless. There is no line of
demarcation between them.

At first view a great difference appears to
exist between the compact and the spongy
substance, but in reality this is not the case.
The degree of condensation is the only dis-
tinction. The spongy substance would become
compact were the sides of its cells pressed
together, and the compact would become spongy
or reticular were its texture loosened by en-
larging the minute cells which may be detected
even in it. Such changes actually occur by
the processes of absorption and deposition in
growing bones. In the perfect bone the cells
are compressed towards its middle to diminish
its bulk, and thereby to accommodate the bel-
lies of the muscles; and they are expanded at
its ends for the purpose of giving security to
the joints by a more extensive surface, and
allowing more room and power to tendons, &c.,
whilst the osseous matter in equal lengths of
bone, whether at centre or extremity, is of nearly
equal weight. The surface of bone in many
places presents a striated appearance; and small
holes or canals are seen on it especially near
the ends of long bones.

Simple inspection of dried and divided bone
carries us thus far in the knowledge of its
structure. But the question still arises, what
is the arrangement of the particles which com-
pose the compact and spongy tissues? Is
bone laminated, or fibrous, or cellular? or
does it partake of a texture in which these
three varieties of disposition are to be found ?
One might imagine there could be no great
difficulty in answering these questions, where
bone is so readily procured, so easily pre-
served, and admits of such varied modes of
examination. It can be viewed in the living
subject, or after death while fresh, or when
prepared by injection, or when all its moisture
is removed. It was long ago discovered to
consist of an earthy and an animal portion,
either of which can be removed, leaving the
other undisturbed in its original form. Yet,
with all these “ appliances and means to boot,”
anatomists have entertained opposite. opinions,
and are not yet quite agreed upon the subject.
Malpighi, the first author who deserves to be
mentioned, thought that bone consisted of
fibres and filaments with an intermediate os-
seous juice: “ constat igitur, ossa coagmentari
filamentis, et fibris per longum ductis in rete
implicitis, que affuso osseo succo. ferrumi-
nantur. in solidam densamque ossis naturam.”
(Op. Posth. p. 47. Lond. 1636.) He also
allowed the existence of lamella, though he
does not put forward its lamellar structure in a
prominent way.* Gagliardi adopted his no-

* We are told by an interesting writer that Mal-
pighi compared these lamellz to the leaves of @ book.
Could this writer have taken “ libri,” in the fol-
lowing passage, to mean book instead of bark, of
which last Malpighi had just been speaking?
‘« Pari incremento procedit natura in ossium aug-
mento. Feetis ossa, et cranium precipué, _fila-
mentorum progressum exhibent; hec non omnino
sibi parallela sunt, et hinc inde breves appendi-

BONE, NORMAL ANATOMY.

tions of a laminated structure, but made
additions, from which Malpighi, at a subse-
quent period, expressed his dissent. He exa-
mined bones long exposed to the weather, or
softened by boiling, and concluded that they
were formed of plates, (lamelle, squamule,
bractez,) held together by processes, in the
form of nails, the shape and direction of which
he minutely describes.* Clopton Havers found
bones composed of plates connected by an
Osseous juice, with pores which ran, some
transversely through the plates, others longitu-
dinally through the entire length of the bone.
Leuwenhoeck thought that the filaments of Mal-
pighi were hollow tubuli.{ Duhamel observed
concentric layers as in wood.§ Haller says, “ Fi-
brosum est (os) sive in laminas et fila divisum
que sulcis separantur.”|| And Monro lays it
down that “bones are composed of a great
many plates, each of which is made up of
fibres or strings united by smaller fibrils.’
About the close of the eighteenth century the
celebrated Scarpa published his work “ De
penitiori ossium structura,” in which he com-
bats former opinions, and asserts that bone is

in every part of a cellular or reticular texture. -
In the first place he shows that we have no-

proof of its /amellated structure ; the appear-
ances produced by calcination, the weather,
disease, &c. on which former anatomists relied,
proving nothing. Calcination is a rude pro-
cess, and acts with different power on the dif-
ferent parts ‘of the same bone as they vary in
density, and divides them irregularly as it
happens to overcome their force of cohesion.
The same thing may be said of the weather.
And exfoliation takes place in the skin, whose

culas filamentosas promunt, quibus invicem col-
ligata rete efformant parum a libri natura distans,
cujus potiores aree et tota fibrarum compages
exsudante osseo succo repletur et tumet.”
Here we have a tissue of fibres and filaments run-
ning in various directions, and forming a net-work
not unlike a book! ! From this quotation, indeed, it
might be thought that our author entirely denied
the existence of plates. However, in the next
sentence he speaks of plana, lamelle, and bractee:
*« Successivis incrementis nova fibrarum plana su-
perinducuntur, que preexistenti lamell@ osseo
agglutinata succo, debitam molem et firmitatem
excitant. Patent autem singula plana resolutione
facta per longum ossium maceratione; integra
namque_ ossez reticulares bractee evelluntur.
In abortibus verd in cranio inchoatum rete evi-
denter conspicitur.”—Anatome Plantarum. Op.
Omn. p. 19, Lond. 1686. :

* «* Natura prudens ossiculis eas transfixit.”
The nails were of four kinds for the outer plates,
viz. ** perpendiculares acuti, perpendiculares ca-
pitati, oblique situati, et inflexi angulum effor-
mantes.” The inner plates, forming the spongy
substance, differed from the outer, and were of
three kinds, the corrugated, the perforated or cri-
briform, and the reticulated. These had a system
of nails peculiar to them: “ alia sine cuspide,
plurima ramusculos rescissos efformant, nonnulla
breviora.”—Anatome Ossium. Lugd. Bat. 1723.

+ Observationes de Ossibus, Auctore Cloptone .

Havers. Amstel. 1731.
Opera Omnia, Lugd. Bat. 1722.

t my.
§ Mém. de l’Academie Roy. des Sciences, 1739, —

41, 42, 43.
Yo era Minora, tom. ii. Laus. 1767.
onro’s Works, Edin, 1781.

BLOOD, NORMAL ANATOMY. 433

cellular texture no one denies. In the next
place he endeavours to establish its reticular
texture; ist, by observations and experiments
on the bones of a chick, made during its
growth; 2d, by treating bones with dilute
muriatic acid, and then putting them in oil of
turpentine to render them transparent. In every
bone, he says, the net-work was conspicuous.
He observed the same in rickets, in exostosis,
and in callus; and still more remarkably in the
bones of the amphibia, reptiles, and fishes. The
conclusion at which Bichat arrived is not very
different: “Ces lames osseuses ne me paroissent
put exister dans la nature.” ‘ Considerons
e tissu compact comme un assemblage de
fibres rapprochées mais nullement separées
par couche.” Blumenbach and Meckel in-
cline to the lamellar arrangement. More re-
cently bone has been submitted to microscopic
examination by Mr. Howship, who agrees with

a that the ultimate texture of bone is not
lamellated but reticular. He coincides, too,
in opinion with Havers and Leuwenhoeck as to
the existence of minute longitudinal canals in
it; and he adds that the canals communicate

- freely with each other, and that a fine vascular

membrane lines them in the foetus, where they
may be seen projecting into the temporary car-
tilage during the growth of bone in the form
of fibres which are tubular.t Bostock says,
** the membrane of bone is composed of plates
very similar in their general form to those of
the cellular texture, and it is probable that the
earthy matter is inserted between these plates,
and thus is likewise disposed to assume the
laminated structure.” And again: “ As we
may presume that the earthy part of the bone
is moulded into its appropriate form by the
membrane into which it is deposited, we may
judge of the structure of the latter by that of
the former, which, from its firmer consistence,
it is more easy to ascertain. Now, whether we
examine bone during its formation in the feetal
state, or after it has had its membrane destroyed
by the action of fire, we find the earth to
assume the appearance of fibres, which, when
the bone is perfected, have a tendency to a
laminated arrangement.” {

It is plain, from the quotations we have
made from some of the most distinguished
writers on the structure of bone, that all before
the time of Scarpa considered it laminated, or
fibrous and laminated, while all, after his

ublication, looked upon it as cellular. In

former, however, we see some intimations
of a reticular texture; in the latter we hear of
a tendency or a disposition to a laminated ar-
rangement. If, with these opinions before us,
we come to examine for ourselves, I think we
shall have no hesitation in agreeing with Scarpa
that it is cellular. At the same time it must
be confessed that the sides of the cells are, in
the compact tissue, so pressed together that
the appearance of laminz is often very striking,

* Anat. Génér. tome iii. pp. 24-6. Par. 1812.
+t Medico-Chirurgical Trans. vols. vi. and‘vii.
J Bostock’s Elementary System of Physiology,
vol. i.
VOL. I.

and, again, that the sides of the cells have, in.
most places, the appearance of fibres. When
the earthy portion is removed by an acid, we
can teaze out the membranous portion with a
pin, and almost demonstrate the fibres. Buta
closer examination will show that we have torn
the cells and destroyed the true texture. The
laminated disposition supposed to be shown by
exfoliation, the weather, burning, &c. may all
be proved to be deceptive; and, indeed, there
seldom can be exhibited a plate, however small,
of equal thickness throughout, which has been
removed by any of these agents. There is,
however, an approach to the laminated ar-
rangement, and every cell is formed of parti-
cles which approach to the form of fibres. The
longitudinal canals of Havers, Leuwenhoeck,
and Howship, probably result from the flattened
cells, and may be deceptive nig eer in
the old bone, or the channels for bloodvessels,
&e.

2. The periosteum and medulla, and the
organization of bone us a part of the living
system.

A. The periosteum is a fibrous membrane
of a dull white colour. It covers bone on
every part of its circumference, except where
enamel takes its place as on the teeth, or car-
tilage as on the articular extremities, or fibro-
cartilage as where tendons play, or tendon as
on sesamoid bones. The fibres which compose
it run in different directions and form a tissue
of great strength. On the long bones the
greater number of fibres take a longitudinal
direction. The superficial ones extend fora
considerable length without interruption; the
deep are short. All interlace with the liga-
ments of the articulations, and become in-
separably united to them, but there is not,
as was formerly imagined, a continuity of
fibres from one bone to the other by means of
the ligaments; on the contrary, the direction
of the fibres in these two organs seldom co-
incides.

The external surface of the periosteum is in
contact with a great variety of parts: muscles,
synovial burse, mucous membranes, vessels
and nerves, rest on it immediately, or are
separated from it by cellular tissue, and thus
permitted to move freely on it. The other
surface is connected to the bone by vessels,
and by numerous prolongations which pass
into the osseous substance and are lost there.
This connexion is weak in early life, and espe-
cially in the centre of the long bones; but in
the more advanced periods the deeper sub-
stance of this membrane becomes identified
with that of the osseous tissue; thus its union
is rendered more intimate, its thickness di-
minished and its density increased. The union
is so close in old age and even in middle life,
that the inner fibres of the periosteum are sup-
posed. to be the seat of calcareous deposition,
and to be converted into bone.

The vascularity of the periosteum may be
easily shown by injection, especially in the
young. Its vessels freely anastomose with
those of the surrounding soft parts, and there
is no point of the external osseous surface

2F

434

which is not perforated with the communi-
cating branches. Some lymphatics have been
discovered in its tissue, but no nerves; how-
ever, the diseases to which it is subject,
the symptoms to which these give rise,
and the changes that follow, leave no doubt
of the existence of both. That cellular
substance enters into its formation is inferred
from some of its morbid phenomena, as gra-
nulation ; and independently of this argument,
on which we do not lay much stress, its exter-
nal fibres are evidently of a mixed nature, com-
bining common cellular membrane with its
own peculiar substance. The proper and
essential part is the dense, inelastic, and very
resisting fibre, by which it is associated with
other fibrous membranes. (See Fisrovus
Tissue.) The older anatomists believed that
the periosteum had its origin from the dura
mater, and might be traced as one continuous
membrane over every bone in the body. Boer-
haave asserts (Prelectiones Academice) that
if we could remove it without rupture, we
should have an exact mould of the skeleton
with all the joints. Its origin from the dura
mater was said to take place through the fora-
mina which transmitted the nerves ; there the
dura mater separated into two layers, one of
which enveloped the nerves as neurilema,
the other the bones as periosteum. But there
does not appear, on close inspection, to be any
actual identity between the dura mater and
periosteum, although they are most intimately
connected ; and there certainly is no continuity
of the latter membrane over the joints. It is
true that we may, at least in young subjects,
after boiling, tear off the articular ligaments
with the periosteum, but the tendons come off
with it too; and in both cases the fibres are
seen to be interlaced, not continuous.

Various uses have been assigned to the peri-
osteum, such as modelling the bone in its
growth and adding new layers to it, for the
further consideration of which we refer to the
article Osrroceny. It is, moreover, also said
to be useful for the purpose of protecting the
bone from the impression of surrounding
muscles, arteries, &c., and vice versa, shield-
ing them from the rough and unyielding
osseous substance ; permitting the soft parts to
move freely without injury; and serving as a
centre for the fibrous system in general. This
last is, in Bichat’s opinion, a most important
use; he considers its attachment to bone is
more for the purpose of affording a point
d’appui to the fibrous system than for any
office it can fulfil with regard to the osseous
system.*

B. Medulla or marrow.—When a longitu-
dinal section of along bone is made, we ob-
serve a large tubular cavity occupying the
shaft, becoming smaller as we recede from the
centre, and replaced in the extremities by the
spongy tissue. This tube is rounded, not
having exactly the triangular form so commonly
presented by the bone externally. Its surface
is rough, especially near the ends, as if it had

* Anat; Gén, tome iii. Par. 18]2.

where it divides into two branches, one for —

alan

BONE, NORMAL ANATOMY. 3 :

originally contained cells which were in some
way or other broken up. All this cavity is
filled with a peculiar, soft, adipose substance—
the medulla (quasi in medio), contained in a
membrane of extreme delicacy.

The medullary membrane, or internal peri-
osteum as it is often called, resembles the
pia mater in structure, being composed of
vessels ramifying minutely in fine cellular
tissue. Its tenuity is such that some anato- 2
mists have doubted its existence, but we have
only to look into any well-boiled marrowbone,
and we shall no longer doubt. It may be
shown too by roasting a bone, or macerating
it for some time in a diluted mineral acid.
This membrane sends numberless prolonga-
tions from its inner surface into the medulla
which it contains. It is to these processes
that the marrow is indebted for its consistence;
they form cells and areole which support and
maintain the vesicles in which the medullary
fat is lodged. They are exquisitely fine, and
almost invisible; we lacerate them with a
touch. The oily substance of the marrow is
not in immediate contact with these cells. It
is contained in distinct vesicles,which are beau-
tifully figured by Havers. The vesicles are
little bags which do not communicate with
each other, but look like a cluster of pearls,
as Monro observes. When bones have been
long buried or macerated, the marrow often
assumes a granular appearance depending on
this vesicular arrangement. A fine artery runs
to each, ramifies on it minutely, and is the
source of its secretion. This vessel may be
demonstrated. Each artery has its accompa-
nying vein, and, though we cannot see absor-
bents and nerves, their presence is inferred
from analogy and various phenomena. Mar-
row is merely a variety of adipose substance,
and to the article on that subject we refer for
the chemical properties and some generalities
respecting it.

Marrow is not confined to the medullary
canal. It is to be found in the cells of the ~
spongy extremities of the long bones, and in
the areole of the short. It exists in the diploe
of the flat bones, and even in the longitudinal
canals and pores of the compact tissue every
where. In all these situations a membrane
lines the osseous cell or pore, and secretes the
contents. The membrane is still finer than
that of the medullary canal, and the oil is less
consistent. The communication between the
membranous lining is kept up by vascular
prolongations, not by a continuity of cavity.
In the bones of the head we find certain cells,
called sinuses, which contain air, not marrow.
They are distinct from the cells of the diploe,
with which they have no communication.
There is a free anastomosis between the vessels —
of the medullary membrane and those of the
bone and periosteum everywhere. heme

Near the middle of the long bones a fora- —
men is observed by which an artery of con- —
siderable size passes in to the medullary cavity, —

either end. These extend to the extremities —
of the canal in a beautiful network on its lining —

BONE, NORMAL ANATOMY.

‘membrane. The artery is erroneously called

the nutritious vessel of the bone. It is ob-
viously intended for the marrow. A vein is
seen to accompany it ; and nerves may also be
demonstrated.

The medullary membrane is possessed of
sensibility. This was long ago shown by Du-
verney.* According to Bichat it enjoys a very
high degree of sensibility in the centre, but
much less towards the ends. Anatomists do
not with him in this observation, nor is
it found very sensible in any part. Patients
seldom complain of pain when, in amputations,
it is rudely lacerated by the teeth of the saw ;
but sometimes they do complain loudly, and
in those cases especially where the operation
is performed below the entrance of the nerve ;
in the opposite case the nerve is probably di-

vided with the soft parts, and the sensibility,

of course, destroyed.

The marrow and the medullary canal vary
much in different periods of life, and under
different circumstances. No medullary cavity
exists in the cartilage which precedes bone;
but Bichat asserts that the membrane is pre-
sent, filled with gelatine of the same ap-
pearance as the rest of the cartilage. An
assertion so improbable a priori, and so con-
trary to all observation, seemed to require some
proof to support it, yet he offers none. When
a cavity is formed at a later period, it is at first
occupied entirely by the artery; a membrane
soon shows itself which contains a reddish
watery substance, of a gelatinous appearance,
not fatty: it may be dried away before the
fire and will not stain paper. To this the true
marrow succeeds, more unctuous and more
abundant as the individual advances in years.
In subjects, however, which have been wasted
by slow disease, and in the very aged, the
Marrow again becomes watery, though not so

as in the foetus. In the cells of the verte-

there never is well-formed marrow. It
there remains through life sanguineous and
almost destitute of oil.

The use of the medullary membrane seems
to be to act as an internal periosteum, or a bed
in which the vessels may ramify before they
enter the osseous substance. Its destruction
to any extent is followed by the death of the
bone. But is the adeps contained in it of any
use? Doubtless it is to the general system a
store of nutriment, which is absorbed, in cases

_ of wasting or marasmus, for the general good ;
__ but to the bone itself perhaps it is of no more
use than so much of any other soft animal
_ substance would be—it fills a space which in the
_ Mechanism of the bone was not to be occupied
_ with calcareous matter.
than the heavy earth of bone, and could at
_ any time be used for the necessities of the
_ animal. We see young bones filled with a

Marrow was lighter

gelatinous fluid, and in birds air takes its
place—a proof that marrow is no wise essen-
tial to the existence of the osseous system.

Various other uses have been assigned ‘to the

marrow, which will not bear examination.

* Mémoires de l’Acad. des Sc. 1700.

435

Blumenbach, Haller, and their predecessors
conceived that it rendered bones more flexible;
but the bones of children, which have little or
no marrow, are much more flexible than those
of adults. Burning a bone renders it brittle,
and this was said to be owing to the destruc-
tion of its oily part; but it is occasioned,
clearly, by the destruction of all its animal
ingredients. Some were of opinion that it
contributed essentially to the growth and nu-
trition of bone and to its union when fractured,
but bones are far advanced in growth before
it appears at all, and they unite faster in
the young than in the old. They unite also
readily in birds. Others looked on it as the
source of synovia; but the very same objec-
tions hold to that supposition, and indeed the
two fluids are quite dissimilar.

According to the law of development, so
generally observed, we find fishes and amphi-
bia, like the human foetus, for the most part
destitute of a medullary canal. The crocodile
and other lizards are, however, exceptions.
Some of these have considerable cavities.
Birds, when young, have an imperfect medulla
in all their bones, but at a later period the
canal in many of them becomes remarkably
developed, and then no longer contains mar-
row ; air takes its place, and fulfils important
offices in the economy of the class. In mam-
malia the internal structure coincides with that
of the human bones, except in those species
which have fins. These approximate to fishes,
and either contain no cavity or a very small
one filled with fluid oil. The medulla of car-
nivorous animals generally is softer than that
of herbivorous.

Organization of bone as a part of the living
system.—The physical properties of bone are
so very peculiar that we cannot much wonder
at the mistakes of the ancient anatomists re-
specting its organization. Some classed it
it amongst the bloodless organs; others even
supposed it to be destitute of vitality; and
superficial observation might countenance the
supposition, for no pain is excited by sawing,
scraping, or cauterizing a bone; but experi-
ment and observation, analogy and disease,
all convince us that it possesses well-developed
systems of arteries, veins, nerves, and most
probably lymphatics, not differing essentially
from those of the soft parts. These are ob-
scured by the presence of calcareous matter,
not obliterated. “ Scrape a bone, and its ves-
sels bleed ; cut or bore a bone, and its granu-
lations sprout up; break a bone, and it will
heal ; or cut a piece away, and more bone will
readily be produced ; hurt it in any way, and it
inflames ; burn it, and it dies; take any proof
of sensibility but the mere feeling of pain,
and it will answer to the proof.” * Animal sen-
sibility was unnecessary, it would even be incon-
venient; it is, therefore, not to be found, ex-
cept in diseased bone, where it sometimes
exhibits itself too acutely.

The presence of bloodvessels may be shown
in various ways. ist. The colour of healthy

* Bell’s Anatomy.
2F 2

436

bone in the living animal is a pale pink, which
becomes much deeper in case of inflammation,
whilst a deadened portion puts on a yellowish
white appearance. When animals are drowned
or strangled, their bones assume a darker hue ;
and in cholera the colour is so deep, and so
thoroughly pervades the osseous tissue, that
no length of maceration will remove it. In all
these cases the colour obviously depends on
the blood contained in the osseous vessels.
2d. It was discovered accidentally by Belchier,

in 1736, that the bones of animals fed on food bj

tinged with madder very quickly become red ;
(a sensible @¢hange is produced in young ani-
mals in twenty-four hours ;) now, whether we
explain this, with most physiologists, by saying
that the earthy matter is coloured in the blood
before it is deposited, or, with Gibson, that it
receives its dye in the bone, the presence of
bloodvessels is equally necessary to account
for the phenomenon. (See OsTEOGENY.)
3d. The most satisfactory proof of vascularity
in bone is afforded by injection. A young
bone may be completely coloured in this way :
the vessels are seen to enter it, and if the
earthy part be removed by an acid, they may
be followed in their fine ramifications through
its tissue.

Arteries‘are found to enter bone under three
modifications. 1st. Numerous small vessels
fil the minute foramina, which may be seen
in the compact substance every where: 2d, a
larger set enter the holes which we see on the
short bones, and near the extremities of the
long ones: and 3d, about the centre of the
long bones considerable branches pass into the
medullary canal, and ramify on the medullary
membrane. These last have been called the
nutritious arteries, a name to which they have
no claim: they are destined for the marrow.
The two first sets are the true nutritious ves-
sels. All, however, freely anastomose with
each other.

The veins merit particular notice. They

Fig. 187.

BONE, NORMAL ANATOMY.

have been investigated by Dupuytren,* and
their course in some of the bones, espe-
cially the flat bones, splendidly figured by
Breschet.t In figs. 187, and 188, copied from
one of Breschet’s plates, a indicates these veins
in the diploe of the cranium: they may be
very easily exposed in the cranium by filing
away the external table with a coarse file.
The first two sets of arteries have no accom-
panying veins, but with the last there always
are veins of a corresponding size. These do
not appear large enough to return all the blood ;
we therefore have others leaving the bone by
foramina, which are proper to them, and
through which no artery passes. They arise in
the spongy tissue by numberless radicles, re-
ceive branches like other veins in their course,
and, after issuing from the compact tissue by
a constricted opening, empty themselves into
the vessels of the neighbouring soft parts.
The canals through which they pass have a
lining of compact substance continuous with
the external surface. The veins, while in the
bone, have only one ,coat, the internal, which
adheres closely to the osseous canal, and can
enjoy no change of size or form. They are,
notwithstanding, furnished with valves.
Nerves, doubtless, exist in bone, although
we cannot demonstrate them in the osseous
substance. But it is not to be supposed that
a part so highly vascular would be destitute
of nerves. Nerves are seen to enter with the
nutritious vessels, and minute filaments pass
into some bones, as the frontal. These nerves,
we may be sure, ramify through eve ;
The sensibility of an inflamed bone indeed
settles the question. | :
Lymphatics have not been found in the inte-
rior of the osseous substance; but they may
be seen on the surface.{ Ina tissue such as ~
that of bone it would be no easy matter to

* Propositions sur quelques points d’Anatomie,
be 2 et d’Anatomie Pathologique. Par.
+ Recherches Anat. sur le systéme veineux.
te ar. 1829,

¢t Beclard. Grainger.

BONE, NORMAL ANATOMY.

exhibit them, even if they existed in great
numbers. That they do so exist we have reason
to think from the phenomena of mollities,
exfoliation, and various other morbid actions,
as well as the changes which daily occur in
the growth of bone.

3. Chemical composition—When bone is
heated to redness in an open fire, some of its
ingredients are consumed, and a white friable
earth is left behind. Again, if bone be ex-

ed for some time to the action of an acid, it

mes soft and flexible. In both cases the
form and size of the original are retained, but
there is considerable loss of weight. These
facts were well known in the infancy of science ;
they were too obvious to escape notice; but it
does not ap that they were explained before
the time of Nesbit in 1736,* nor very satis-
factorily then. The existence of an earthy and
an animal matter was afterwards proved by
Herissant, who showed, by experiment, that
acids did not soften the osseous substance as a
whole, but removed from it the earthy portion;
and that the soft animal matter was always
present, but concealed by an earthy “ incrus-
tation” of its fibres.+ The action of fire on
the animal portion was easily explained. Some
time after this Gahn discovered that the earth
was principally a phosphate of lime ; and later
chemists, especially Berzelius, have minutely
investigated the nature and proportions of these
different ingredients. It is now ascertained
that bones contain several earthy salts, varying
a little in different animals; that the earthy
and the animal parts do not always bear the
same proportion to each other in the different
classes; and that even in the same individual
age and situation give rise to varieties.

It was long believed that fat formed an
essential part of bone, and that very important
properties depended on its mixture with the
osseous tissue; but this opinion was quite
erroneous. Fat is not always present, and
when it is, it invariably belongs to the medulla,
which may be looked upon as a distinct struc-
ture superadded to bone. It is, as it were,
an accidental deposit, and is not to be con-
sidered in the analysis.

On removing the fat and periosteum, if we
suspend a bone for some days in-diluted mu-
riatie acid, the earthy part is dissolved, whilst
nearly all the animal portion remains untouched.
This last is soft, translucent, and of a yellowish
white colour. It is called the cartilage of bone.
When washed and dried it contracts a little,
assumes a deeper colour, though still retaining
some translucency, becomes hard and tough,
and weighs about one-third of the original
bone. This substance yields, on being boiled,
a quantity of gelatine, which in young subjects
is very considerable, forming nearly all the
cartilage, but in the old a soft, white, elastic
substance still remains, possessing the figure of
the bone. According to Hatchet’s experiments

* Human Ostcogeny, by R. Nesbit, M.D. p.
31. Lond. 1736.

+ Mémoires de l’Academie Royale des Sciences,

1758.

407

this last has the properties of coagulated albu-
men.* Berzelius,t however, shows that all
the cartilage may be resolved by boiling into a
clear colourless gelatine, which leaves on the
filter only a very small quantity of fibrous sub-
stance, the débris of vessels. He does not
admit the existence of any albuminous nidus,
and even looks upon the gelatine as the pro-
duct of a decomposition effected by coction on
the peculiar cellular basis of bone.

The earth of bone is principally subphos-
hate of lime; it also contains carbonate of
ime and minute quantities of other salts. The
following is the analysis, as given by Berzelius,
of bone deprived of its oil, blood, and perios-

teum :—

Bones of man. Of the ox.

Cartilage completely solu-
ble in water ........ ‘ s217 ¢ 33°30

NOMIC. sain adieu ‘eamet Mis

Subphosphate of lime with
a little fluate of lime.... 53°04 57°35
Carbonate of lime ...... 11°30 3°85
Phosphate of magnesia -. 1°16 2°09

Soda, and a very little mu-
riate of soda.......... 1°20 3°45
100°00 100°00

The proportion of earthy and animal matter
is the same generally in man and the other
mammalia. In birds there is more of the
animal part which does not perfectly dissolve
than in mammalia. In reptiles and osseous fishes
the cartilage of bones approaches in its nature
to the substance which, in cartilaginous fishes,
is the substitute for bone. This substance is
of a peculiar nature; it yields neither gelatine
nor albumen, but is more analogous to inspis-
sated mucus than to any thing else.

The earthy salts are not always in the same
proportion to each other in different animals.
We have seen that they are not the same in
man and the ox. Barros gives the following
table :—

Phosphate of lime. Carbonate of lime.

Lion .. 950 wccccose 25
NEED < a's 95.540 BBO voci's sac 0193
Fowl) issc00 es O89" si. 05.2 10°4
BIO Ws o's ose OSD 25 dR 9-4
rae ° O19 5. eae 53

With respect to varieties depending on age
and situation, we have a table of the proportions
of animal matter and earth as found by Dr.
John Davy in several experiments, from which
it appears that old bones contain more earth
than young ones, and that the bones of the
head have a greater proportion than those of
the extremities.{

As to the exact nature of the earthy salts,
we have given the results obtained by Ber-
zelius as the latest and most accurate. But
it, may be right to state that differences of

* Philosophical Transactions, 1800.
+ Traité de Chimie, Par. 1833.

t See Monro’s Elements of Anatomy, vol. i.
Edinb. 1825.

438

opinion exist on this point. Even Berzelius
expresses a doubt whether magnesia is met
with as a phosphate ora carbonate. We find
iron mentioned by Fourcroy and Vauquelin as
present in bone. This, according to Berzelius,
depends on the red blood which its vessels
happen to contain. They also mention silica,
alumina, and phosphate but no fluate of am-
monia.

4. Its peculiarities in other animals.—In
the course of this article we have noted the
most striking of those peculiarities, so that
little need be said under the present head.

The Radiata, Articulata, and Mollusca
have coverings which somewhat resemble bone,
and are considered by some physiologists as the
osseous system of these classes. This opinion
will be examined in another place.

Fishes.— Cartilaginous fishes have very little
earthy matter in their skeleton, so that their
bones scarcely deserve the name. They are very
flexible, elastic, homogeneous, and semi-trans-
parent, and in chemical composition resemble
inspissated mucus. Osseous fishes have bones
properly so called. They are more flexible
than in the higher classes, have no medullary
cavity, little of the spongy tissue, and make
no approach to the laminated arrangement.

Amphibia have no appearance of lamine in
their bones, nor, with the exception of the
crocodile, a medullary cavity. In chemical
composition they resemble those of fishes.

Birds have firm, elastic, and thin bones,
shewing less of the cellular and more of the
laminated disposition than we meet with in the
other classes. They have large and well deve-
loped cavities, which contain air instead of
medulla.

Mammalia.—The bones of the cetacea are
coarse and fibrous externally. Within they are
spongy or cellular, but the cells assume a re-
markable tubular disposition. There is no
medullary canal. The bones of quadrupeds
do not differ much from those of man. In
general they are of a coarser texture, and in
some, as in those of the head of the elephant,
we find very extensive air-cells.

BIBLIOGRAPHY.—Leuwenhoeck, Microscop. Obs.
in Phil. Trans. 1674 and 1678. Malpighi, De
ossium structura, in Kj. Anat. Plantar. tol. Lond.
1675, et in Ej. Op. Posth. Venet. 1743, Lond. 1697.
Havers, Osteologia nova, 8vo. Lond. 1681. Gagli-
ardi, Anatome ossium, 8vo. Lugd. Bat. 1723.
De La Sine, Mém. i. et ii. sur l’organization des
Os. Mém. de Paris, 1751. Albinus, De construc-
tione ossium, in Annot. Acad. lib. vii. Scarpa,
De penitiori ossium structura Com. 4to. Lips. 1769;
4to. Paris, 1804; Ticin. 1827, s.t.: De anat. et
pathol. oss. Malacarne, Auct. ad osteologiam, &c.
Ludwigii et Scarpe, Padov. 1801. Caldani, Mem.
sulla struttura della ossa umana e bovina, 4to.
Padov. 1804. Howship, Microscopic observations
on the structure of bone, in Med. Chir. Trans.
vol. vii. Medici, Esperienze intorno alla tessitura
organ. delle ossa, in Opusc. Scientif. t. ii. Bologna,
1818. Speranza, Consid. sul. tessitura organ. delle
ossa, Bolog. 1819. Ilmoni, Physiol. syst. oss,
spec. i. et ii. 4to. Abow, 1825,-6. See also the
various systems of general and descriptive anatomy
and of physiology, and further in the Bibliography
of OssEOUS SysTeM and OSTEOGENY.

( Charles Benson. )

BONE, PATHOLOGICAL CONDITIONS OF.

BONE, PATHOLOGICAL CONDI-
TIONS OF .—tThe bones, as the foundations of
the animal system, as the passive organs of loco-
motion, required necessarily to be firm and com-
paratively inelastic and unyielding, qualities
which we have seen in the preceding article are
imparted to them by the addition to their original
animal elements of a saline or earthy substance,
consisting principally of eae sige of lime. —
It is obvious that this difference of structure. ,
and constitution must have considerable in-
fluence in modifying the diseases to which ;
they are liable, and in giving to the affections '
of these organs many of their distinguishing
peculiarities. In considering, therefore, the
phenomena exhibited in the various patholo-
gical conditions of the osseous system, not
only must the presence of this unorganized
earthy substance be constantly borne in mind,
but even its relative amount, its abundance or
deficiency must command attention. In early
life, when the animal material preponderates
in quantity, the bones are highly vascular, and
comparatively soft, flexible, and springy, and
though liable to many serious diseases, they
are very apt to escape the effects of injury:
fracture is uncommon in infancy; and in child-
hood the bones, bending rather than breaking,
often exhibit that partial fracture which has
been likened to a “ branch of a tree that
yields to an attempt to break it while it still
retains its sap.”* The powers of repair are
commensurate with the extent of vascular or-
ganization at this period; fracture is quickly
re-united, and its effects so regulated by the
subsequent growth of the bone that permanent
deformity is a very infrequent occurrence.

But this activity in the osseous system in
early life has its evils. The period of youth,
between absolute childhood and puberty, is
that in which disease is most easily and, there-
fore, most frequently developed, and although
extensive powers of reparation are constantly
exhibited in recovery after caries, in re-
production after necrosis &c., still are the
operations that lead to these results languid
and too often inefficient;—circumstances that
may be attributed partly to peculiarity of or-
ganization in the structure affected, but per-
haps with more propriety to the influence of
some general constitutional taint over which
medicine exerts but slender control.

The osseous system cannot be considered as
having attained maturity until a period sub-
sequent to the age of puberty, most commonly
somewhere between the twenty-seventh and
thirtieth years. At this time bone is calculated
most perfectly to answer its purposes in the
animal economy: it is then least liable to ~
disease ; and if fractures and other injuries —
are more frequent, it is only because indivi- —
duals are now more exposed to them. The —
effects of these injuries are in general repaired
sufficiently well, but if deformity has be
produced it will be permanent, because
bone has ceased to grow.

ca ate A Se ee eet

* See a paper on this subject by Dr. Hart, vol. re
Dublin Journal of Medical Science. =

BONE, PATHOLOGICAL CONDITIONS OF.

As life advances, the osseous system un-
dergoes many obvious alterations. The
shape of some bones is altered: the natural
curvatures of the long bones, for example, are
increased ; the direction of the processes and
parts of others is changed, the most remarkable
example of which occurs in the neck of the
thigh-bone ; and their powers of affording sup-
pe and resisting violence are obviously en-
eebled. This senile fragility has been gene-
rally supposed to arise from an increase in the
earthy material of the bones. The opinion,
however, has not been invariably borne out by
the results of chemical analysis of bones at
different periods of life, and has been objected
to by M. Ribes,* who, after extensive obser-
vation and enquiry, was led to believe “ that
the fragility of bones depended essentially on
a change of action being established within
them, and that all the parts entering into the
texture of bones are really in less quantity in
the aged than in younger individuals.” If
by “a change of action” in the above passage
is meant that gradual decrease of the vital
properties observed in every organ and in every
tissue as man declines into the vale of years,

DISEASES OF THE

439

we cordially agree in the opinion; being
satisfied that the results of chemical or me-
chanical enquiries, however true in themselves,
will always be insufficient to explain the ope-
rations carried on within a living body.

Having offered these preliminary remarks,
we proceed with an attempt at an arrangement
of the pathology of the osseous system, fully
aware, indeed, that every classification of dis-
ease must be more or less artificial, and, there-~
fore, open to objection. Perhaps it may be
advantageously considered under the three fol-
lowing heads. 1. Cases in which there is a
real or supposed derangement or imperfection
in the processes carried: on within the bone
itself in order to its maintenance in the -
normal or healthy condition. 2. Cases in
which there is inflammation of the bone,
whether produced by injury, appearing idio-
pathically, or connected with some specific
taint. The pathological conditions of the pe-
riosteum are so intimately connected with this
part of the subject, that some reference to its
diseases must of necessity be made. 3. Cases
in which there is alteration of the original struc-
ture or development of a new one; as thus:—

OSSEOUS SYSTEM.

Crass 1. Derangements of internal functions.
a. Deticiency of the calca-
reous deposit ......Rachitis.
b. Superabundance of the
calcareous deposit .. Fragility.
c. Absorption of the calca-
reous deposit ...... Mollities.
d. Absorption of both con-
stituents ..........Atrophy.
Crass 11. Inflammation.
a. Simple inflammation ..Adhesion ............e0++ee++. Union of fracture.
Suppuration. ..,..0....e+++.+++..Abscess in bone.
RINCCTBUION ry . o.d0 4 04 0a orale 50 $5 Caries.
Mortification ....6+..ee0+2- 2000+ Exfoliation.
Death with regeneration ,......... Necrosis.
b.. Specific inflammation , .Scrofula..........ee++ee++0e02«+Absorption of cancelli.

Syphilis .........5.

Crass 111. Structural diseases.

Deposit of a cheesy
substance.

Softening of the bone.

Abscess.

Caries.

«tne «+ .+es-Deposit of fluid between
the periosteum and
bone. Node.

Caries.

a. Spina ventosa ........Development of a new cavity within a
bone, with unnatural contents.

Exostosis ..........+..Growth of a tumour in or from a bone,

which may consist of .,........ Bone.

Cartilage.
Both structures mixed.

Osteo-sarcoma ........Alteration of structure with deposit of

a new material.

Cancer.+

Fungus hematodes.+

Bloody cellulated
mour within bone.

tu-

* We refer our readers for a summary of M. Ribes’ opinions, &c. to the Dictionnaire des Sciences

Médicales, vol. xxxviii. p. 456 et seq.

+ These discases are generally, if not alwavs, propagated from a ‘jacent -parts or structures.

440

Rickets—The consideration of this subject
has been too frequently mixed up with that of
the disease entitled mollities ossium (osteo-
malaxie ), or with that of the interstitial absorp-
tion of bone which occurs in aged persons.
Rachitis seems not to be so much a softening
of bone that had previously been solid and
perfect, as an interruption in the first instance
of the process of ossification. It is a disease
of early life, generally commencing, or at
least first observed about the period when the
infant should make its earliest attempts to walk,
and rarely appearing after the age of two years.
It would appear that the disease should be
considered as connected with inadequate nu-
trition throughout the body generally, rather
than as being confined to the osseous system ;
its effects are only most obviously marked on
that system; and it is quite certain that all
the bones of the skeleton are more or less af-
fected, although particular local causes com-
monly produce much greater deformity in one
than in another.

The early symptoms of rickets are invariably
those of imperfect or deranged nutrition, pale-
ness of skin, flaccidity of fibre, &e. Along
with these symptoms or shortly succeeding to
them the deformities appear which cause the
disease to be ranked amongst the affections of
the osseous system. In mild cases these ex-
tend no farther than to an increase in the cur-
vature of some of the long bones and an aug-
mented expansion of their extremities. Whether
from its supporting the whole weight of the body
or from the action of the strong museles behind
it, the tibia generally suffers in a remarkable
degree: the legs are not only bent forwards,
the curve being sharp and sudden about the
lower third of the bone, but they are twisted in
such a manner as to bring the internal ankle
below its proper level, deformities which, not-
withstanding a perfect recovery, are never com-
pletely removed afterwards. Rickets, consi-
dered alone, is not very dangerous to life: in
most instances it proceeds no farther than has
been already described—the visceral derange-
ments are either subdued or subside sponta-
neously, the healthy functions are re-estab-
lished, and amongst them that of ossification,
and the patient soon becomes enabled to per-
form the ordinary motions, while the deformit
in some slight degree disappears. But if the
disease is severe or protracted, or complicated
with a scrofulous taint, it generally leaves
tokens behind it which embitter the patient’s
future existence, or hurry him to a premature
grave. Sometimes the head becomes flattened,
or pushed so as to project backwards, or is
otherwise strangely deformed. More frequently
still the chest suffers in shape, either in the
ribs, the spine, or in both, and the compressed
and contracted thorax, or laterally curved spine,
with all their accompaniments and consequences
of deranged respiration, will be the result. But
of all the parts which suffer from this disease,
perhaps the pelvis is that which is most fre-
quently engaged. Placed between the spine
and the thighs, it is the fulcrum and centre on
which numerous motions-are performed ; it is

BONE, PATHOLOGICAL CONDITIONS OF.

OP V9 ah

surrounded by powerful muscles and subjected
to irregular and unequal pressure ; and it also
sustains the weight of the principal part of the
body. Hence arise the strangest and some-
times the most complicated distortions, and
woe to the female who at the age of woman- -
hood becomes pregnant under such cireum-
stances. The remote consequences of rickets
may, therefore, be far more formidable than
the immediate.

The actual condition of a bone with reference
to its structure is the next point to which we
must direct our attention. Isthere an absolute
deficiency in the quantity of ossific matter .
secreted, the place of which is supplied (espe-
cially about the epiphyses of the bones) by a |
soft substance which increases their bulk? or is :
the earthy material removed by absorption
previous to the deposition of this softer sub-
stance? The question is not easily answered,
for patients seldom die of rickets alone; and
when they perish, it 1s generally in consequence |
of some complication of scrofula producing |
hydrocephalus, tabes mesenterica, glandular q

abscesses, or, it may be, caries; and it is evi-
dent that the examination of a case so mixed
cannot afford a satisfactory demonstration of
the disease itself. It cannot, therefore, be a
matter of surprise if some difference of opinion :
has existed. The following is the description ’
of a ricketty bone as given by Boyer.* It is ;
lighter, of a red or brown colour, pierced by a
great number of dilated bloodvessels, porous
and spongy, soft and compressible, moistened
with a sort of sanies that may be pressed out
as from a sponge, or rather from leather that
has been soaked to maceration. The walls of
the medullary cylinder of the long bones of
the extremities are greatly thinned, whilst the
bones of the skull are increased in thickness
and become spongy, and, as it were, reticulated.
Both the one and the other, but especially the
long bones, have acquired a remarkable sup-
pleness, but when bent beyond a certain point
they break: and the fracture takes place more
easily if the inflexion is made rapidly. The
medullary cavity of the long bones contains,
instead of marrow, a reddish serosity, totally
devoid of that fat and oily character which
appertains to marrow in its natural state. The
result of Mr. Stanley’st experience is that the
consistence of a ricketty bone is but slightly
different from that of common cartilage, ‘an
Opinion more consonant with our notions of
the disease than Boyer’s exaggerated descrip-
tion is calculated to convey. We ourselves
have never met with that extreme degree of
softness which has been occasionally described,
or which would permit of the bone being di-
vided by aknife. Meckelf states that the bones
of ricketty patients are soft, spongy, flexible, —
and curved, both in situations where they are
subjected to muscular actions, and where they
have some weight to support. In the meantime —

a ae

is ned Traité des Maladies Chirurgicales, tom.
iii. p ,

+ Medico-Chirurgical Transactions, vol. vii.
+ Meckel, Manuel d’Anatomie, tom. i. p. 344.

BONE, PATHOLOGICAL CONDITIONS OF. 441

they receive more blood: The periosteum has
undergone analogous changes. The chemical
composition isnotthe same throughout. Thus,
on the one hand, thereis notalways the same rela-
tion between the respective proportions of phos-
phoric acid and lime—sometimes too much,
sometimes too little of the acid: on the other,
the proportion between the animal and earthy
substance varies considerably. Sometimes the
quantity of animal matter is greatly increased,
so that the relation is 74:26, or even 75,8: 24,2,
or so far as 79,54: 20,6. Often it is the same
as that met with in the healthy condition, or it is
even less, as 25,5 : 74,5,* although the bones are
spongy. These differences depend probably
on the intensity, and, more particularly, on the
period of the disease ; but they prove, at least,
that the essence of rickets does not consist in
an original deficiency of earthy material.

It is unnecessary to quote any farther autho-
rities to shew that no universality of opinion
prevails as to the pathology of this important
disease, and that it still requires careful and
accurate investigation. It seems, however, to
be agreed on, that when the patient begins to
recover, a great activity may be observed in the
deposition of the earthy material, and that it is
principally deposited where it is most wanted,
viz. on the concave surfaces of the curves.

Fragilitas—We have classed a brittle con-
dition of the bones under the head of a dispro-
portionate abundance of the earthy substance,
rather in compliance with a doctrine that was
once universally believed, and perhaps is still
pretty generally admitted, than as the statement
of a fact that may be supported by evidence.
It was supposed that the presence of a greater
quantity of phosphate of lime rendered the
bone short-grained and dry, and _ therefore
more liable to snap across ; and this condition
of bone, as peculiarly appertaining to old age,
has been placed by Boyer among the predis-

sing causes of fracture.t The opinions of

ibes on this subject, and the doubt cast by
chemical analysis on the ordinary explanations
of a softened condition of bone on the one
hand, and of its fragility on the other, have

been already noticed, and, notwithstanding some

attention to the subject, we are obliged to leave
it without even attempting a solution of the
difficulty ; the results even of several series of
experiments, which were instituted in the years
1831 and 1832, with a view to the elucidation
of this difficult question, scarcely deserve to be
stated, as they were in every respect unsatis-
factory. We compared the respective thick-
ness of the thigh-bone in the adult and the
aged, the section being made exactly in the
middle: we weighed equal. lengths of similar
bones—we softened equal lengths and equal
weights by means of dilute muriatic acid—
and we burned equal portions and weights
also, with a view of comparing them under
these different circumstances, but could never

* These chemical results are quoted by Meckel
from Monro’s Outlines of Anatomy.
nat Traité des Maladies Chirurgicales, tom. iii. p.

arrive at any fixed or certain conclusions. In
one remarkable instance the bone of a wo-
man, who must have been seventy or eighty
years of age, was thicker, stronger, and con-
tained more both of the animal and earthy
materials than any adult bone with which it
was compared. We were, therefore, obliged
to adopt M. Ribes’ theory of “ a change of
action,’ just as we see the muscle of an old
man incompetent to such a display of strength
as would be easy to that of a younger person,
although the latter may be smaller, and pos-
sessed apparently of less toughness of fibre.

Fragility seems to exist under two different
conditions, one derived from, or having rela-
tion to, some defect or imperfection in the
bone itself; the other being rather a symptom
of some other disease than a disease itself, and
arising from some vice or taint in the constitu-
tion. The former of these is exhibited in the
fragility occasionally observed in the bones of
some young persons, and more constantly in
those of the old; but it may be remarked that
the causes that produce this fragility (whatever
they are) do not interfere with the restorative
powers of the part. True, a fractured bone is
tedious in uniting, and is frequently followed
by unpleasant consequences in aged persons,
but in such all the vital powers exhibit evi-
dence of sluggishness and debility; whilst in
youth, so far from fragility interfering with the
process of union, fractured bones have been
observed to be consolidated in even less than
the usual period. But when any particular
condition of constitution or any disease seems
to be the exciting cause of fragility, it may
also be regarded as a cause of subsequent non-
union. Of these, cancer, fungus hematodes,
and sea-scurvy, seem to furnish the most nu-
merous and best authenticated instances ; sy-
philis has been added, probably from the fact
of some fractures remaining disunited until
the patients had been subjected to a course of
mercury; its influence, however, is question-
able, unless where it had previously produced
caries. A state of pregnancy or of lactation
has been mentioned as predisposing to fracture,
and impeding or delaying the process of re-
union; but however the observation might
have been occasioned by a few solitary cases,
it is not borne out by general experience.

In the fragility of early youth, and where
union would take place quickly and kindly, it
is not to be expected that the bone (if there
was an opportunity of examining it) should
present any morbid appearances unless the
evidences of its physical weakness in the small-
ness of its diameter and the thinness of its
walls should be so considered. In the aged,
as all persons are not afflicted with this fragility,
so are there some whose bones cannot be dis-
tinguished from those of the healthy adult.
As to the ordinary characters of the bones of
old persons, Mr. Wilson remarks they are
never found so friable and fragile as to crumble
like a calcined bone, but, on the contrary, they
contain a large quantity of oil; and when
dried after death, they are so greasy as to be
unfit to be preserved as preparations. Their

442

organized vascular partis diminished, but their
oily animal matter is increased.

Mollities ossium is a disease, the phenomena
of which are directly the reverse of those we
have just considered. In fragilitas the bone
snaps across from the most trifling causes: in
mollities it is flexible, bends in every direction,
and, of course, is useless for the purposes of
support or motion. The morbid condition
seems to arise from a want of accordance be-
tween the secreting and absorbing vessels of
the bones affected: if the earthy material is
not secreted at all or in insufficient quantity,
or if itis absorbed too rapidly, mollities wall
be the consequence, and we may presume that
there will be variety in the rate of its progress
and in the intensity of its symptoms, according
to the degree of derangement of function ex-
isting at different times. It may thus be easily
comprehended how fragility of bone may be
an early symptom of mollities, at a period
when the earthy material has been removed to
an extent which renders the bone completely
flexible.

Of the causes that produce this curious dis-
ease, or of the change of structure that occurs
at an early period, nothing is certainly known,
indeed, it is so rare an affection that little oppor-
tunity for anatomical or chemical examination
in any of its stages has occurred. Boyer
seems to regret our deficiency in this branch of
pathological knowledge, and doubts that there
are a sufficient number of authentic cases to
establish such a difference between the fragility
and the softness of bone as to authorize them
being considered distinct diseases. There can
be no doubt that in the cases of cancer, &c.
which have occasioned, or been attended by, a
softening of the bones, the symptom of fra-
gility has been observed at one period or
another, and perhaps there is no such thing as
a softening of the bones independent of some
malignant taint in the constitution. There
is scarcely any case,” observes the author just
quoted, “ of a pure and simple softening
(ramollissement) of the bones:” not one (we
believe) in which they have been found merely
deprived of their earthy constituent, leaving
the animal material healthy and unaltered,
like a bone that had been prepared by macera-
tion in muriatic acid ; whilst all the dissections
of mollities exhibit such decided alterations of
structure as to justify an opinion of the exis-
tence of some malignant disposition in the
entire system. This view of the case ought to
remove the disease from the position it holds
in our classification, and place it among the
derangements of structure, only that there is
some reason for supposing that the first and
early stages may be accompanied with the
absorption of the phosphate of lime, and it
must therefore signify little where we place an
affection, of the nature of which we are con-
fessedly so ignorant.

There is, however, a softness and _pliability
of bone (we use the word softness in opposi-
tion to softening) in which there is no malig-
nant tendency whatever. It is original and
congenital, that is, from birth the process of

BONE, PATHOLOGICAL CONDITIONS OF.

ossification is suspended in some part or limb. —
We have seen two instances of this: oe .
remarkable occurred in a poor man forty years”
of age, whose right arm was perfectly flexible, —
and of course powerless. He stated that he
had been so from birth, but in every other re-
spect had enjoyed the very besthealth; heearned =
his livelihood with the other arm, with which a
he had become wonderfully dextrous. On 4
the nature of the cause that could suspend a
particular process of nutrition in one limb, the
remainder of the body being perfectly healthy,
it would be useless to speculate at present.

The most extraordinary instance of mollities
ossium on record is that of Madame Supiot.
It may be found at length detailed by Brom-
field, to whom it was communicated by M.
Supe, surgeon to the hospital of La Charité.*

is woman appears to have been an in-
valid for fifteen years, during the first five of
which she suffered from great weakness in her
loins and lower extremities, accompanied by
great pain, which, however, did not prevent
her giving birth to two children within the
time. When M. Supe saw her, “ the trunk
was extremely shortened, and did not exceed
twenty-three inches in length. The thorax
was exceedingly ill-formed, and the bones of
the upper extremity were greatly distorted ;
those of the lower were very much bent; and
the thigh-bones became so extremely pliable
as to permit the legs to be turned upwards,
insomuch that her feet lay on each side of her
head. The softness of her bones daily in-
creased to the hour of her death.” It is unne-
cessary to dwell-on the symptoms under which
she laboured, as it must be obvious that no
one viscus could perform its function properly
in such an extraordinary mass of deformity as
she eventually became. On dissection, M.
Supe says, “the bones, one may truly say,
had arrived at the utmost degree of softness,
as we have not heard of any observations
similar to this case. In effect we have, now
and then, remarked that bones become mem-
branous and of the consistence of flesh, but I
believe there never was before seen an instance
of the osseous particles in the great bones of
the extremities being so totally dissolved, leav-
ing no more than the form of a cylinder by
the periosteum remaining unhurt.”

Mr. Goocht relates a case which lasted five
years, and which at an early period exhibited
the symptoms of fragility, the patient having
broken her leg as she was walking from the bed
to her chair and heard the bones snap. The
winter after breaking her leg,she hadsymptoms __
of scurvy, and bled much at the gums, and
throughout her illness her legs and thighs were __
cedematous, and subject to excoriate, discharg- _
ing a thin yellow ichor. From the commence-
ment of the attack the bones continued to
softer, and a year before her death “ sh
breathed with difficulty, and the thorax ap-
peared so much straitened as necessarily 1

* Bromfield’s Surgery, vol. iii. p. 30. ie s
+ The Chirurgical Works of Benjamin
vol, ii. p. 393,

BONE, PATHOLOGICAL CONDITIONS OF.

impede the expansion of the lungs: her spine
was much distorted, and any motion of the
vertebree of the loins excited extreme pain:
her legs and thighs being quite useless, she
was confined to her bed in a sitting posture :
the bones she rested upon, having lost their
solidity, were much spread, and the ends of
her fingers and thumbs, by frequent efforts to
raise herself, were become very broad, with a
curvature of their phalanges: she now mea-
sured but four feet, though before this disease
she was five feet and a half high and well
shaped.” After death she was found wanting
in her natural stature two feet and two inches.

“ All her bones except her teeth were more
or less affected, and scarcely any would resist
the knife: those of the head, thorax, spine,
and pelvis were nearly of the same degree of
softness; those of the lower extremities were
much more dissolved than those of the upper
or of any other part; they were changed into
a kind of parenchymatous substance like soft
dark-coloured liver without the least offensive
smell. I cut through the whole length without
turning the edge of the knife, and found less
resistance than firm muscular flesh would have
made, meeting only here and there with bony
lamine, thin as an egg-shell.

“ Those bones were most dissolved which
in their natural state are most compact, and
contain most marrow in their cavities. This
circumstance may appear more worthy of ob-
servation as it held throughout, and looks
as if the wonderful change they had undergone
was occasioned by the marrow having acquired
a dissolving quality; for it was evident the
dissolution began internally by the bony laminz
remaining here and there on the outside and
no where else, and the pain in the beginning
of the disease not being increased by external
pressure.”

Mr. Wilson* met with three cases, of one
of which he gives the dissection, which in
some respects resembles the preceding. As it
exhibited the symptom of fragility,—indeed the
Symptoms throughout were rather such as
should 2 ea to fragilitas than mollities,
for most of the bones of the skeleton had given
way, some of which were imperfectly united,
and many not at all,—as the bones were altered
into a substance not very unlike that described
by Gooch, and as the disease evidently com-
menced within, we subjoin an extract from
the dissection, which will be sufficient without
entering into the more minute details.

** All the bones were diseased. The ossa
brachiorum were so soft that I very readil
divided them with a common scalpel from their
heads until near the condyles. Immediately
at the condyles both bones were hard, and the
articulating cartilages had a natural healthy
appearance ; both bones had been fractured ;
in one the fracture had not united, and in the
other there were several fractures which had
united very imperfectly. The compact sub-
stance of the bone was in some places not

* Wilson’s Lectures on the Bones and Joints,
p- 253. |

443

thicker than an egg-shell: the cancelli were
totally destroyed, and the cavities in the mid-
dle of the bones were filled up with a substance
which seemed to have been originally extra-
vasated and coagulated blood, but which had
become vascular, and had much oil deposited
in the cells within it. These substances ap-
peared to have produced absorption of part of
the bone from their enlargement and internal
pressure, for in some places the external surface
of the bone was removed and tumours allowed
to extend through the openings.”

In confirmation of the opinion that this
disease is produced by some malignant taint in
the constitution, it may be proper to add that
hitherto it has baffled every mode of treatment.
It continues its progress without stop or inter-
ruption, and is inevitably fatal.

Inflammation—osteitis—The exact process
that is carried on within an inflamed part*.
seems not to be satisfactorily understood, al-
though the subject has exercised the ingenuity
and employed the research of many who have
distinguished themselves in the cultivation of
pathological science. If this position is true
with regard to the softer and more external
structures which are open to examination both
by the touch and eye, it must be still more so
with reference to the osseous system, the parts
of which are more or less deep-seated and
concealed from observation. We know, how-
ever, that the process of inflammation is greatly
modified by the structure of the part affected,
or perhaps more particularly by its vascular
organization, some powerfully resisting the
inroads of disease, and repairing its ravages
with wonderful activity, while others exhibit
as remarkable a want of energy, seem scarcely
capable of a struggle, and run at once into
mortification. But as the bones, besides their
animal ingredients, contain an earthy material
which must exert considerable influence on the
phenomena, the progress, and the results of
inflammation, it will be necessary to examine
the subject with reference to the nature of the
structure particularly affected.

A bone in its healthy condition is copiously
supplied with bloodvessels.+ When examined
on its external surface stripped of its perios-
teum, it exhibits a bluish-grey colour, evidently
produced by a quantity of blood contained
within it. When it is cut, or when the perios-
teum is torn from it, a number of bloody
specks are seen; and the cancellated structure
in which the marrow is lodged is always red,
particularly in young subjects. By Mr. How-
ship’s observations it appears that “ the small
space occupied by the bloodvessels of the
canals (within the bones) compared with that
which is found to be allotted to the secretions
and membranes of these cavities, distinctly
proves that the circulation must, under all
circumstances, enjoy as much freedom here as
elsewhere ; and the intimate connexion formed
by these canals between all parts of the bones

* Generally spoken of as the proximate cause of
inflammation. ; ‘

+ See Howship’s Papers in the Medico-Chirurgi-
cal Transactions. —

444

and the surrounding soft parts affords the
strongest grounds for believing that the minute
vascular and membranous organization of the
bones is as susceptible of impressions from
irritation or sympathy as the muscular, glandu-
lar, or other soft structures of the body.” The
bones in common with other parts are conse-
quently subject to inflammation with all its
consequences of adhesion, suppuration, granu-
lation, ulceration, &c. &c., but subject to the
following modifications which result from the
peculiarities of structure and material compo-
sition indicated, and the intimate connexion
just alluded to between them and the adjacent
soft parts.

1. The connexion between the bone and
periosteum is so complete that it is not easy to
conceive how inflammation of a bone can occur
without its membranes being more or less en-
gaged, and therefore it is difficult to meet with
a case of diseased bone unaccompanied by
periostitis.

2. The effects of inflammation on the mem-
brane and on the bone must be different. One
structure can swell, the other in the first in-
stance cannot; and hence the vessels of the
bone itself in a state of debility and compressed
by an unyielding substance are very liable to
die, whilst those of the periosteum tumefy and
exhibit a more mitigated form of disease.
Thus the periosteum in inflammation is gene-
rally found swollen or thickened, and detached
from the bone underneath, which is then usually
either carious or necrosed.

3. Those bones or parts of bones which are
hardest and firmest usually die soonest, whence
Mr. Wilson’s remark that “ they are the soonest
cured,” the process of exfoliation being set up
by the surrounding living parts in order to
remove that which is dead.

4. In the various processes of repair and re-
production the periosteum largely participates,
and if this latter membrane has been injured
or torn off, the vessels of the adjacent cellular
tissue seem to assume a new function in order
to supply its place. Thus, if a portion of the
scalp is torn down, leaving the cranium per-
fectly denuded, it by no means follows that
the bone must exfoliate if the flap has been
carefully laid down and _ still preserves its
vitality ; but perhaps the best illustration may
be drawn from some cases of necrosis succeed-
ing to injuries by which the periosteum had
been removed, in which the process of regene-
ration is commenced and completed notwith-
standing.

Thus far, then, we have seen that there is little
difference between the inflammatory process in
bone and in any other structure of similar or
equal vascular organization; the chief or cha-
racteristic peculiarities must therefore depend
on the presence of the earthy material, which
we shall find influencing the phenomena of
the disease, but perhaps more especially its
progress. Thus, whether the operation is sana-
tive or otherwise—whether adhesion is to be
accomplished, ulceration or granulation is to
be set up, ora > aR or dead portion of bone
is to be removed—the progress of the work is

BONE, PATHOLOGICAL CONDITIONS OF.

more sluggish, and its ultimate accomplishment
deferred to a much later period, than in any
other animal structure. When a bone is wound-
ed, coagulating lymph is thrown outas quickly
and with as much facility as from any other
tissue, but nothing can be more familiarly
known than that it will require a length of time
before consolidation is effected, and the solution
of continuity is repaired. |
The process of ulcerative absorption in any
structure is scarcely understood either as to the
stimulus which first determines the vessels to
this action or their modus operandi subse-
quently; still less can we comprehend how a
solid unorganized material like the earthy phos-
hate of bone comes to be thus removed.
hat this process is not performed with the
same facility as in softer structures of equal or
inferior vascularity is obvious from the tedious-
ness of its progress, a delay that is therefore
attributable to the presence of this earthy sub-
stance. The absorption of the earthy particles
takes place under two different conditions; one
without the secretion of purulent matter (dry
caries), examples of which may be seen in the
caries of bones compressed by aneurismal tu-
mours, and in some cases of angular curvature
of the spine. It is of importance to remark
this kind of caries, and to observe that its pro-
gress is equally or perhaps more rapid than
that in which purulent matter is secreted.
Many writers have assumed that pus possessed
a solvent quality, and by thus preparing the
ossific matter for absorption, materially assisted
in the process—an idea which the preceding
observation strongly militates against. In the
other there is a secretion of purulent matter,
and the case is analogous to suppuration and
ulceration in the softer tissues, except that the
process is still very slow, and in general the
odour of the matter is very offensive.
Adhesion.* Formation of callus.—The phe-
nomena attendant on this process are most
easily and familiarly observed in the re-union
of fractures. It is very remarkable, however,
that considering the number of celebrated men
who have directed their attention to this subject,
and the opportunities for observation that are
so constantly occurring, nothing has yet been
positively determined. We have theories in
abundance, apparently founded on and sup-
ported by experiment, but still so contradictory
that it is impossible not to entertain a suspicion
that the theories were in general formed in the
first instance, and the facts, if they did not
immediately apply, wrested a little in order to
support them afterwards. Hence this part of
our pathological studies consists of little more
than a history of opinions and doctrines neces-
sary to be known as constituting part of the
literature of the profession, but totally unavail-
able to any practical purpose. Ss
The most ancient explanation of the process
by which callus is formed is, that it was per-
fected by means of a viscous fluid poured out, —
around and between the fragments of a divided
bone, which were thus mechanically glued to-

* The adhesive ossific inflammation of Hunter. 4

¥
i.
4
,

BONE, PATHOLOGICAL CONDITIONS OF. 445

gether. This fluid, which was termed the osse-
Ous juice, was supposed to acquire the requi-
Site consistence afterwards, and thus became
the medium of a firm union. Nothing, how-
ever, was said of the time or manner in which
the consolidation was effected, nor of the
absorption of the superabundant part of this
fluid subsequently.

The first who doubted this theory of the
osseous juice, or rather who thought it insuffi-
cient, was Duhamel, a man of extraordinary
ingenuity, but unfortunately not a physician,
and therefore not qualified to examine or to
explain the results of vital actions. He adopted
his ideas as to the formation and growth of
bone analogically from trees and vegetables,
and supposing the periosteum to answer the
same purpose to bone that the bark did to the
wood, he conceived that ossification went for-
ward by the conversion of the internal layer of
periosteum into bone. It was natural, having
formed this theory as to the original conforma-
tion, to advance it still farther into an explana-
tion of the mode of re-union in fracture. He
said that the extremities of the torn periosteum
covering the fragments swelled ; that they met,
and uniting, formed a kind of brace or ferule
inside and outside of the fracture; sometimes,
in case of the external membrane being torn
off, the internal answered every purpose alone ;
sometimes the external periosteum was sufti-
cient, but in every case it was this that perfected
the operation. It is needless now to canvass
a theory that has long since been given up as
untenable, yet as if to show how little of
novelty can be expected in physiological rea-
soning, it will be found that an opinion not
very far removed from this in its bearings was
the one entertained by Dupuytren, so recently
lost to science.

The next opinion to be noticed is that of
Haller. This great physiologist, who was a
cotemporary of Duhamel,* quite dissatisfied
with the ideas entertained in his time on this
subject, endeavoured to develope the truth by
experiments, and conducted many, in conjunc-
tion with a pupil of his named Dethlef. The
result was, that the process of re-union ap-
peared to him to be the same as that of the
original ossification; 1st, that a gelatinous or
gluey substance is poured out around the ends
of the fragments; 2d, that this substance be-
comes converted into genuine cartilage; and
lastly, that an osseous deposit is laid down in
the cartilage, forms a ring of bone, and gra-
dually increases until the entire ossification is
completed. This theory is principally objec-
tionable in the regularity with which these
changes are said to take place, whereas it is
more than questionable whether this gelatinous
fluid, the origin of the callus, ever becomes car-
tilage atall. Doubtless it is altered in con-
sistence and becomes hard and firm, opaque
and elastic, and thus far resembles cartilage in
its sensible qualities ;+ but it is tinged of a red

* Haller was born a short time after Duhamel,
and died before him, this latter philosopher having
attained the age of 82.

+ Macdonald,

colour by feeding the animal with madder,
which is not the case with cartilage; and che-
mical analysis shews its nature to be osseous
and not cartilaginous. However, the experi-
ments of Haller and Dethlef are entitled to
great attention from the care with which they
were conducted, and with a little modification
their results are probably not very remote from
truth.

Hunter, so happy in the doctrine of adhe-
sion, endeavoured to extend it as widely as
possib!e, and has certainly simplified both our
notions with respect to divided parts and our
practice in procuring union, although his cor-
rectness in considering effused blood to be the
medium of that union has been frequently
doubted. According to him, the first effect of
fracture is, the effusion of blood from the
ruptured vessels of the bone and the adjacent
structures: this blood becomes organised by
vessels shooting into it; whilst in the mean
time the ends of the fragments inflame, and
this inflammation produces adhesion in the
surfaces that are even, and a disposition in the
scales or points of the broken edges that re-
main, to be removed by absorption. Pretty
nearly the same are the conclusions to which
Mr. Howship arrived after a series of expe-
riments conducted with great accuracy and
minuteness. ‘This paper is in the ninth volume
of the Medico-Chirurgical Transactions, in
which these experiments (performed on the
fractured bones of rabbits) are detailed and
illustrated with engravings. They refer to the
appearances observed on the third day, on the
fifth, the ninth, the fifteenth, the twenty-third,
and thirty-second days after the fracture. The
relation of these experiments singly would
occupy more space than can be appropriated to
this part of the subject, and we must therefore
confine ourselves to the conclusions as drawn
from them by the author himself. He concludes
that the first effect of fracture is extravasation
of blood into the surrounding cellular struc-
tures, principally that of the periosteum ; into
the medullary cavities of both fragments and
between their fractured extremities. This blood
soon coagulates ; after some further time its
colouring matter disappears; and the thick-
ened periosteum becoming more firm assumes
the sensible characters of cartilage. The de-
position of osseous matter takes place within
the coagulum, beginning at the part nearest the
fracture and extending gradually from this
point: it even commences in the clot situated
within the medullary cavity before the colour-
ing matter is removed; but under every cir-
cumstance and in every situation, we are to
understand that the coagulum of blood is the
nidus of ossification and the medium of union
between the fragments. Notwithstanding the
respect due to such high authority, there are
many who do not believe in the possibility of
effused blood becoming organised, and look
with doubt and suspicion on every experiment
and every observation by which such a doc-
trine is sought to be established. They reason,
that if, under any circumstances, blood became
the medium of union, we ought to leave the

446

surface of a stump or other wound covered
with clotted blood, and spare ourselves all the
labour and pains we employ in removing it
and placing the cut surfaces cleanly in appo-
sition with each other. And they also remark
that when a clot of blood is left behind, how
very commonly, instead of becoming organised,
it lies as a dead substance in the wound, im-
des the union, promotes suppuration, and
imparts to the discharge a putrid and offensive
odour. These pathologists suppose that in
many instances the fibrine of the blood has
been mistaken for coagulating lymph, which
is the natural product of the vessels in the
adhesive stage of inflammation, is capable of
becoming organised, and ought to be the legi-
timate seat of any deposit to be afterwards
laid down in completing the process of union.
We now pass to the theory of Bordenave,
Bichat, and Richerand, who make the union
of fractures analogous to that of the soft parts
by the second intention, or by means of !granu-
lation. Like other pathologists, they have
supported their opinions by observation and
experiment; and without entering into the
minuter circumstances connected with this hy-
pothesis, it will be necessary to mention some
very familiar facts that bear upon the case.
In necrosis, the surface of the new or grow-
ing bone is often seen covered with granu-
lations. In cases of amputation, when the
bone protrudes after eight or ten days, the cut
extremity is observed to be fungoid and granu-
lated. And in some cases of compound frac-
ture we can observe the process of granulation
going forward, and actually see that it is thus
the union is completed. It nevertheless ap-
pears very doubtful whether granulation has
any part in the process of uniting a fracture,
unless where a communication exists between
the broken ends of the fragments and the ex-
ternal air. In a compound fracture, or in the
case of a bone protruding from a stump, there
will be granulations, often to a degree of
excessive exuberance; and in them there will
be a deposit of osseous substance, because
new structures always assume to a certain
extent the nature of the parts from which they
are produced ; but in a case of simple fracture,
where there is no wound, no communication
with the atmosphere, and not a single drop
of purulent matter is formed, it is very doubt-
ful whether granulations could exist; at least
their existence has never been demonstrated.
Amongst modern pathologists, Meckel’s* opi-
nion is entitled to very great respect, although
we may not be disposed to accede implicitly
to his views. He ranks among those who
consider the process of consolidation in frac-
ture to be similar to that of original ossi-
fication, and states, that at first there is an
effusion of a gelatinous substance which gra-
dually becomes firmer and more solid in con-
sistence, and is converted into cartilage, in the
interior of which osseous nuclei appear that
join to each other and to the broken ends of
the bone, and also envelope any fragments that

* Manuel d’Anatomie, tom. i. p. 335,

BONE, PATHOLOGICAL CONDITIONS OF.

the spicule or scales become rounded off in —
order that the surrounding parts may not suffer
injury or irritation. It is not necessary to the
perfection of this union that the ends of the
fragments should be accurately in contact: —
it is sufficient if they lie against each other,
and then the union occurs by the same means,
and exactly on the principle of anchylosis
taking place between different bones. It must
be understood that this ossific deposit is laid
down both external to and within the bone;
that when union is complete, the bone is di-
vided into two cavities internally; and that,
for a length of time afterwards or for ever,
it may be known, by making a longitudinal
section, whether a bone had ever been broken
or not. He further states that the part sur-
rounded and joined by ossified callus is
stronger and firmer than any other, and to all
appearance this observation is correct, but it is
contrary to one of Mr. Howship’s experiments,
who saw the callus break down and crumble
away in an attempt to calcine it, and therefore
concluded that it was softer and more highly
animalized.

Hitherto we have noticed a number of the-
ories, all of which, with the exception of that
of Duhamel, bear a strong similarity to each
other, the principal points of difference being,
1. as to whether the soft gelatinous substance,
which all agree in having seen, was the fibrine
of the blood deprived of its colouring matter,
or genuine coagulating lymph effused by in-
flamed vessels: 2. whether this in process of
time was changed into real cartilage, or the
osseous deposition took place into this lymph 4

.

may have been detached. At the ees ee

,
b
‘

‘very much inspissated: and, 3. whether any-

thing like adhesion happened, or the conso-
lidation was perfected after the manner of
union by the second intention, namely, by
granulation. We now proceed to take a view
of a new theory bearing some resemblance to
that of Duhamel, and supported by the autho-
rity of Dupuytren. He supposes that there
are two distinct and different processes in the
union of bone. First, that there is a callus
formed like a brace or ferule round the frag-
ments externally, with a plug of the same
material within, the object of this provision
being, to hold the ends of the fracture in ap-
position whilst the union that is to be per-
manent is going forward: thus we are to
imagine a kind of natural splint placed around
and within the fractured: pieces in order to
preserve them in situ. This preliminary pro-
cess commences almost immediately after the
accident, and is completed in the space of
from four to six weeks. Matters remain thus,
while the ends of the bones are becoming per-
manently united, which they arein about eight
months, during the latter period of which time
the mass of new material is declining in size, —
and is eventually removed so as to leave the
bone of its natural extent and figure. The —
formation of this first callus, which he calls —
“ cal provisoire,” is attributed to the perios-
teum and occasionally to all the surrounding
structures, and in the centre of it he sup- —

BONE, PATHOLOGICAL CONDITIONS OF.

poses the fracture to remain for a considerable
time un-united, the limb being, of course,
weaker here, so that, in the event of the occur-
rence of a new fracture, this will be the spot
in which it will give way. The second or per-
manent callus, which he calls “ cal definitif,”
is the actual medium of union between the
fragments, and remains like the cicatrix of a
wound in the soft parts.

It must appear curious to the reader that no
positive conclusion should have been obtained
on a point which has occasioned so much
inquiry, and which apparently was so easy of
determination. It is open to experiment;
obvious to the senses; and there are few
sources of fallacy except such as might arise
from previously adopted views of the expe-
rimentalist, and perhaps from different periods
puring the progress of ossification being chosen
or making the observations, and the same
thing, of course, being seen under different
circumstances. We think it might have been
reasonably suspected from analogy, (and the
experiments of Breschet and Villermé have
confirmed the idea,) that nature, in the sim-
plicity of her operations, produced every where
similar effects from similar causes, and that,
in whatever manner the re-union of divided
soft parts was accomplished, the same would
hold good as to bone, only allowing a longer
time in order to admit of the consolidation of
the lymph by osseous deposition. And such
is probably the fact. In an incredibly short
Space of time after the receipt of a fracture,
the process of repair seems to be actively com-
menced : coagulating lymph is effused in con-
siderable quantity, probably mixed with blood,
as the coagulum is found to possess a more
than ordinary firmness and consistence. At
the end of the second day the torn edges of
the periosteum are evidently thickened, pulpy,
and vascular, easily receiving coloured in-
jections. At the end of the fourth day, we
have seen the sharp edge of the fracture be-
ginning to be rounded off. Where the surfaces
of the fragments are broad and thick, it is easy
to observe them coated with a deep layer of
lymph, which adheres to them tenaciously from
avery early period. If the fragments are in
apposition, the torn extremities of the peri-
osteum are united by the intervention of this
tyne the membrane appears greatly thick-
ened also, and seems to afford a kind of pro-
tection to the fracture; or, otherwise, an im-
mense and irregular mass of lymph is thrown
out around both fragments, filling up all the
space that has been occasioned by the dis-
Biosetcnt of the bones and the laceration of
the soft parts. In effecting this deposition, all
the vessels of the part, those of the bone,
eo, and adjacent structures, seem to

equally engaged. In process of time this
lymph becomes organised, assumes a Jigamen-
tous rather than a cartilaginous appearance,
although, strictly speaking, the new structure
“saree not the true characters of either, and

nally is converted into bone by the simul-
taneous establishment of numerous but irre-
gular specks. of ossification. This process

447

varies as to the time required for its com-

pletion according to a number of circum-
stances, such as the situation of the bone, the
part of it broken, the apposition of the frag-
ments, rest, and many others that need not be
enumerated here ; as well as the age and con-
stitution of the patient, which exert such
marked influence on all cases, that it is im-
possible to lay down certain rules for calcu-
lating the time that may be required for the
union of any given fracture.

The process of re-union, however, is some-
times very imperfectly performed; sometimes
it is suspended indefinitely, and occasionally
it is not performed at all. Of the causes that
occasion these deviations from the natural and
usual progress of ossific union we are in .ge-
neral ignorant, although there are many cases
in which former experience may enable us to
predict the occurrence of such an event. It
has been already stated that the diseases which
occasion a fragility of bone will be likely to
interfere with its subsequent union, and in
these cases little more is accomplished than the
removal of the sharp spiculated edges by ab-
sorption : the presence of such a constitutional
derangement as would occasion a bone to give
way in the effort to turn in bed will be suf-
ficient to explain its want of re-union. But
these are not the cases generally met with.
When there is an un-united fracture, or as it
has been termed, a false joint, the ends of the
fragments are not smooth and polished moving
on each other like articulated surfaces, but are
joined together by the intervention of a liga-
mento-cartilaginous substance, which, accord-
ing to its extent, is more or less flexible, and
of course incapacitates the bone from the per-
formance of its functions of support and mo-
tion. This imperfect union occurs in some
bones with wonderful regularity; we may, for
instance, calculate on such an event in frac-
tures of the neck of the thigh, and in the trans-
verse fracture of the olecranon and patella ;
but it happens at other times quite unexpect-
edly, in cases wherein we could suspect no
possible cause, in which there may have been
no neglect, no impropriety of treatment, to
lead to such aresult. We have lately seen
two cases of fractured femur remain un-united
at the end of five and six months in the per-
sons of fine and apparently healthy young
men, although the ends of the bones were kept
in apposition, and in every other respect the
treatment was correct.

The chief causes* to which this imperfect
union has been attributed are a removal, or
rather a withdrawing of the broken surface of
one fragment from the other, a want of vascu-
larity in one of the fragments, and the fracture
not being maintained in a state of uninter-
rupted repose.

The frequency of this occurrence in fractures
of the above-mentioned bones, in which the
fragments are always withdrawn from each
other, was too remarkable not to lead to the
connexion of the circumstances as cause and

* Sir A. Cooper on Dislocations and Fractures.

448

effect, the only objection being that thé result
is not uniform and universal. Fractures have
been submitted to each of the above con-
ditions, more especially to the maintenance of
exact co-aptation for months, yet has no
ossific union been produced ; and again a firm
consolidation has taken place between two
bones, the extremities of which had been
sawed off and the parts placed under circum-
stances that could not permit of the approxima-
tion of the divided surfaces. We have a case
published as having occurred in the hospital
of La Charité in Paris, in which the os calcis
was broken; and although the surfaces of the
fragments were never completely separated,
yet the usual kind of ligamentous connexion
took place; and for proof that a solid union
may occur under the circumstances above-
stated, we refer our readers to Mr. Crampton’s
second case of extirpation of the knee-joint.*

If we can subscribe to Larrey’s opinion that
only the vessels of the bone itself can minister
to osseous union, and that those of the peri-
osteum and adjacent structures are incom-
petent to such function, (an opinion in which
he is to a certain extent supported by Mr.
Liston,+) it is obvious that a union between
fragments at a distance from each other would
be difficult if not impossible. Here, however,
as well as in every other part of the history
of ossific union, it is only conjecture. We
have nothing like substantial definite proof,
and must only rest satisfied with a knowledge
of the fact without being able to explain it,
that the medium of union between fragments,
the faces of which are withdrawn from each
other, is in general not osseous.

Whatever may be the operation of this cause,
that of the other two is by no means so ob-
vious. The second { has been generally ad-
duced in explanation of the non-union of
fractures of the neck of the thigh-bone, but
perhaps without being entitled to the impor-
tance that has been attached to it. If a part
is only possessed of a degree of organisation
barely sufficient to preserve its vitality in ordi-
nary circumstances, but inadequate to accom-
plish any process of repair, it should follow
that any violence offered to it ought to cause
its death, or at least its removal by the ab-
sorbents, and in such case the caries or exfo-
liation of a fragment of bone might be easily
understood. But these are not the results of
fracture of the neck of the femur except in
very rare and anomalous cases; and,-on the
contrary, there is scarcely an example of exami-
nation after death that did not exhibit a conside-
rable display of reparative energy, although the
results were not such as to produce ossific union.
Professor Colles§ has published twelve cases
of post-mortem examinations of this accident,
in some of which he observed the appearance
of ivory-like patches on the surface of the
superior fragment, evidently proving the ex-

* Dublin Hospital Reports, vol. iv. p. 236.
t Elements of Surgery.

¢ Cooper’s Surgical Essays,

§ Dublin Hospital Reports, vol. ii. p. 334.

BONE, PATHOLOGICAL CONDITIONS OF.

istence of considerable ossifie powers in this
part. Besides, this condition of the head of
the bone has been assumed rather than proved.
On the most attentive examination, we have not
been able to observe any deficiency of vascu-
larity within it; and if there is any difference
between the head and neck and shaft, we are
rather disposed to believe the head to be pos-
sessed of the highest degree of organization.

The advantage of the most absolute rest to the
cure of fracture has been observed in all ages,
and yet is it doubtful how far its influence on
the question under consideration can be appre-
ciated. Few fractures can be kept in a more
perfect state of repose than those of the patella
or of the heel, yet the union in both these
cases is always ligamentous. It would appear
as if constant although very trifling motion
was more prejudicial than occasional shocks
however rude and productive of greater dis-
turbance, and this perhaps is the reason why
false joints so frequently occur after fractures
of the clavicle, even although the fragments
have never suffered displacement, as occurs
when the bone is broken near its acromial
extremity.

Suppuration may occur in the osseous tissue
under a variety of conditions, as to situation,
as to the character of the matter, and as to
whether it is produced by or connected with
any constitutional or specific taint. Pus is
occasionally, though not frequently contained
in a cyst or sac within a bone, as the result of
inflammation, and resembling the common ab-
scess in the soft parts. These collections are
never very large; they are usually situated in
the thick and spongy parts of the bones, and
have a strong tendency to burst into the neigh-
bouring joint. We have seen a case of abscess
in the head of the tibia, which appeared to
have opened into the knee-joint even after it
had burst externally. The disease had pre-
viously existed for months, the patient suf-
fering very little either locally or constitutionally
until the communication with the cavity of the
articulation was established, when the symp-
toms became so aggravated as to demand the
speedy removal of the limb. The symptoms
of suppuration within a bone are exceedingly
obscure, nor is there any certainty until the
abscess has burst and a probe can be passed
into the cavity, particularly if the inflammation
has not been attended with enlargement of the
bone. The pain is said to be agonizing, but
this is not universally true, and we may infer
that suppuration has taken place “ by the
violent symptoms of active inflammation les-
sening, by cold fits and shivering occurring,
by a remission of pain with an increased sense
of weight in the part; but all these are fal-
lacious, and no external marks of suppuration
are at first to be observed, the disease affecting
parts too deep to be seen with the eye or felt
with the finger.”* ,

Suppuration on the surface of a bone is of —
very common occurrence, and so constantly —
complicated with affections of the periosteum,

OS Eee

i ie) ae

* Wilson on the Bones and Joints.

BONE, PATHOLOGICAL CONDITIONS OF.

that it is difficult to say which structure is the
source of the purulent secretion; the disease,
indeed, is generally described under the name
of periostitis. We are disposed, however, to
regard it as inflammation of the bone in the
first instance, although the membrane comes
very soon to be engaged; because in many
cases the pain in the commencement is not ag-
gravated by external pressure, which it uni-
formly is when the periosteum is engaged,
and also because in very severe cases, such as
pe hep periostei, a portion of the bone

ecomes carious, and is lost even from the
earliest period. It is most frequently ob-
served in connexion with some constitutional
taint, such as scrofula or syphilis,* but it may
and very often does appear purely as an idio-
pathic disease. “ Inflammation of the pe-
riosteum, unconnected with any known con-
Stitutional disease, is an affection with which
practical surgeons are well acquainted. It is
remarkable, however, that a disease so impor-
tant in its consequences and of such frequent
occurrence, should not have been noticed in any
systematic work, nor have been made the sub-
ject of any separate inquiry.” +

Whether we consider this affection to belong
primarily and principally to the bone or pe-
riosteum, it is certain that the former structure
always is engaged, and shews the most evident
marks of activity in the disease, although this,
perhaps, may in part be explained by the
fibrous texture of the membrane and its defi-
cient organization. The bone is always in-
flamed. Even in the most chronic case that
leads only to a thickened condition of the pe-
riosteum, the bone is preternaturally vascular,
and so soft that it is often difficult in such
cases to distinguish the limits between the sof-
tened bone and the condensed periosteum.{
In the severer forms, the bone, unable to sus-
tain itself under the excitement, is always dead,
and must be gotten rid of by ulceration or
exfoliation: in these cases the periosteum is
detached, and a fluid, very generally thin,
ichorous, and fetid, is interposed between them.
Between these extremes there is every possible
variety, and, therefore, there will be vast dif-
ferences in the results of the inflammation,

* Of all the causes that produce these affections
of the bones, an irregular or protracted use of mer-
cuty seems to be the most efficacious. Many sur-
geons of the present day doubt whether a suppu-
rating node is a true or genuine venereal symptom.
We have learned from an experienced army surgeon,
who spent many years on the western coast of Africa,
where the venereal disease is not known, but where
mercury is profusely employed in the treatment of
liver complaints and other diseases incident to the
climate, that affections of the bones, resembling
those considered to be venereal, are of exceeding
frequency. It is a remark worthy of attention to
the curious in such matters, that nodes, &c. formed
no Spee of the symptoms of syphilis as first observed
and described, and that the first practitioner who
noticed them (John de Vigo, 1519,) is mentioned
by Astruc, (page 158,) as an eminent promoter of

mercurial method of cure, and as having by that
Mmeaus acquired great reputation and riches.

+ See a paper by Mr. Crampton, in the Dub,
Hosp. Reports, vol. i.

¢ Ibid.

VOL. I.

449

sometimes in the mere thickening of the pe-
riosteum, sometimes in the deposition of more
bony matter, or the apparent ossification of the
membrane (exostosis) ; occasionally in the ab-
sorption of the bone, and most frequently,
particularly in specific diseases, in that which
1S Our more immediate object, the deposition of
purulent matter.

A node is a swelling situated over a bone,
hard, firm, and exquisitely tender to the touch,
not round or circumscribed at its base, but
gradually subsiding to the level of the adjacent
parts, and not discoloured on the surface. It is
at all times painful (except in some scrofulous
cases), and when arising from a venereal cause,
is subject to nocturnal exacerbations of great
severity. The morbid anatomy of the disease
is not always the same even when examined
at the same period of duration, being modified
by a number of circumstances, such as the
age of the subject and consequent vascularity
of the bones; the structure of the bone en-
gaged being solid and firm or soft and spongy ;
but more particularly by the fact of the disease
being idiopathic, or produced by some consti-
tutional affection. The scrofulous diseases of
bones seldom or never exhibit the symptom of
nodes, although attended by suppuration, be-
cause they affect their substance rather than
their surfaces : idiopathic nodes, or those pro-
duced by injury, do not suppurate unless the
violence used is great; on the contrary, these
are cases which so frequently terminate in
thickening of the periosteum, &c., and often,
when cut into, scarcely afford any perceptible
discharge. The venereal or mercurial node
offers the best example of suppuration. At an
early period, if an opportunity occurs for exa-
mination, the periosteum round the margin of
the effusion shews a more than ordinary degree
of vascularity ; immediately covering the tu-
mour it is somewhat paler, more opaque and
thickened. The bone underneath is denuded
and soon runs into caries; between it and the
membrane the matter is deposited, thin in con-
sistence, dark-coloured, and sanious.

There are other forms of suppuration on the.
surface of a bone of too much interest and im-
portance to be omitted, such as those large de-
pots which occasionally occur after severe in-
juries or operations, as the accompaniments of
inflammation of the veins, or as the sequele
of acute fevers. In general, the matter is in
great quantity and of a good and healthy cha-
racter, though sometimes it is otherwise, and
particularly in that form which attacks a stump
after amputation. We have seen the entire
remnant of the bone up to the next articulation
denuded of its periosteum, while quantities of
green and fetid pus could be pressed from the
very depths of the wound. In these cases the
veins are generally inflamed, the divided ends
of the muscles pale, flaccid, and sloughy, and
the patient seldom or never recovers. Where
the deposition has taken place after fever, if
the patient is young and the constitution has
enabled him to combat the original disease, a
recovery very frequently takes place by the
process of necrosis. :

G

450

_ Caries from a scrofulous cause, generally, if
not always, commences in the cancellated
structure ; that from syphilis affects the firmer
and more external parts of the bone. The
former attacks the ends of the long bones and
the spongy and cuboid bones generally; the
latter, the centres of the long bones and the flat
ones. Veuereal nodes principally affect the
bones which are nearest to the surface of the
body, the skull, the tibia, or the sternum; it.
being rare to see the humerus or femur thus
diseased, whilst they are by no means exempt
from idiopathic or strumous inflammation.
But the most remarkable differences to be ob-
served between caries arising from a specific
cause, and that which occurs idivpathically or
from injury in a constitution otherwise good,
occur in the progress and termination of the
disease. The process seems to be analogous
to that of ulceration in the softer tissues, and
when recovery takes place, it is by granulation
and cicatrization in like manner. Thus, if we
suppose an abscess to occur on the surface of a
bone in a healthy man, when it is opened or
has burst, we find that a scale or shell has lost
its vitality and must be thrown off by exfo-
liation, and soon exuberant and florid granula-
tions are seen springing froin below as if to
force the offending substance off, and the dis-
charge from the cavity is healthy pus. On the
other hand, if a venereal node is upened on the
skull, the pericranium is here detached, the
table is carious and will exfoliate, but there is
(as long as the taiut remains) no effort at re-

-paration ; the discharge is thin, ichorous, and
unhealthy ; and if we may judge by the repre-
sentations we see of venereal caries, (for in
modern times mercury is not so wnsparingly
used and real specimens are not numerous,) the
disease would progress until the skull was
fairly corroded through. Again, the lymph
secreted in scrofulous inflammation is not
healthy, and there are seldom granulations;
whilst the matter is either of that whey-like
appearance so remarkable in such affections, or
else a foul and fetid sanies. Every one con-
versant with surgery must know how tedious
and obstinate a scrofulous caries is, and how

Peavently it involves the loss of limb or of

ife.

The true scrofulous affection of the bones
occurs so frequently in this country as to re-
quire particular attention; it constitutes the
vast majority of the diseases of the osseous
system that we are called upon to see and to
treat. It commences (as we have said) in the
cellular or cancellated structure. In the first
instance there is an increase of vascularity,
which, though not always apparent to the eye,
may easily be proved by injection. Next,
there is an absorption of the natural contents
of the cancelli, and in their room a substance
is deposited of a yellow or white colour that
has been described as resembling cheese in
consistence ; it is, however, most probably a
species of that flocculent unorganized lymph,
such as is seen coating the cysts of scrofulous
abscesses. The cancelli themselves are oc-
casional!y removed, and masses or patches of

BONE, PATHOLOGICAL CONDITIONS OF.

-gravation of symptoms, both local and

this unorganized material depx
stead, hence the bone becomes li
soft as to allow of being cut with a kr
is remarkable that the disease may have e
up to this period, when it is probably inc
ble, without much pain and without exte he
swelling to attract attention to the mischief
underneath. In the Museum of the School of
Anatowy, &c. of Park-street, Dublin, there is
a preparation to illustrate necrosis of the centre
of the shaft of the thigh-bone, for which the __
limb was amputated. The patient during life
never complained of the knee, neither was.
there the smallest enlargement of the articula-
tion; yet after removal the condyles of the
femur internally were completely softened, the
external shell of solid bone being reduced in
thickness nearly to that of parchment, the can-
cellated structure completely removed, and its
place occupied by this cheesy substance.

This condition of the bones is considered by
Mr. Lloyd* as constituting the first stage of
scrofulous disease, and he justly remarks that
it is quite uncertain how long they may con-
tinue in this state without further mischief
taking place. The next step is the erosion or
absorption of the cartilages, if the affection is
situated in the head of a bone, (see Jornt,) or
otherwise near an articulation, and probably
about the same period the external soft parts
sympathise, and lymph is extensively deposited
around the deep fibrous tissues in the neigh-
bourhood. This lymph is afterwards to be-
come the seat of abscesses, which always
communicate with the diseased bone, and very
generally with the cavity of the adjacent joint.
The limb or part is now swollen: the tume-
faction is round and well defined, tolerably
firm in consistence, and elastic to the touch ;
the colour of the skin is of a more than ordi-
nary paleness, and its surface is marked by
the meandering lines of numerous small blue
veins. The growth of the tumour seems to be
limited, for having reached a given size it
becomes stationary and never increases, al-
though the disease may appear at times even
more fully developed. Subsequently the pain
is very variable; that attending on scrofulous
diseases being generally described as dull and
heavy rather than acute, but this idea must be
received with some limitation, for occasionally
the very reverse is the truth. We have seen
some patients the victims of most intense irri-
tation and suffering throughout every stage of —
carious ulceration ; and even when it is other-
wise, they are always liable to severe exacer-
bations on any injudicious attempt at motion, —
any improper diet or other irregularity. In
all cases there seems to be a considerable ag-
OTL:
tutional, about the period when suppuration
established, and whilst the matter is progres
ing towards the surface. -*

It may be a long time before the tum
gives indications of being about to burst.
nally, partly perhaps from the imperfect
zation of the lymph by which the

* See Lloyd on Scrofula. if

<a CY

oo ey a em ve? Way” me

BONE, PATHOLOGICAL CONDITIONS OF.

secreted, and partly because it seldom takes
the shortest route to the surface, but proceeds
by devious and intricate windings. At length
the tumour, at one limited and almost circum-
scribed spot, becomes soft, then assumes a dark
red or purple colour, finally a small slough
forms on the surface and it bursts, giving exit
in general to a greater quantity of matter than
the size of the abscess would have led us to
anticipate. The abscess does not collapse, and
although the discharge may continue in pro-
fusion for months, the size of the tumefaction
is never proportionally diminished. After it
has burst, a small papilla of very red granu-
lation (a most unfailing symptom of the exis-
tence of a diseased bone underneath) is pushed
out through the aperture. From the centre of
this a sinall drop of matter can generally be
pressed, and through it the discharge flows ;
never for obvious reasons profusely at a time,
but still so constantly as to soil the dressings
and the bed-clothes extensively in a single
night. Whena probe is passed down to the
bottom of this ulcer, which it is not easy al-
ways to accomplish, the bone is felt completely
denuded, soft and rotten, and the instrument
sinks into it with very little resistance. Most
frequently the earthy material of the bone is
removed by the absorbents ; sometimes a sinall
portion of it thus detached is washed off by
the discharge, and is occasionally found block-
ing up the litle orifice, occasioning a good
deal of irritation and pain, and almost always
an access of fever. Sometimes the remains of
the bone come away in a larger mass, quite
dead, light, and porous, and, when dried, per-
fectly friable.

Previous to the formation of the matter,

however, the pathological state of the bone has

undergone a remarkable change. Hitherto we
have seen that an increase of vascularity oc-
curred at an early period, and preceded the
deposition of the soft and cheesy substance;
but in proportion as this deposit is increased in
quantity, the vascularity decreases, and with it
the vitality of the bone. “If a scrofulous
bone be injected at an early period,” says Mr.
Lloyd, “ or before the whole of its cancellous
Structure is altered, the injection very freely
enters its vessels; but if it be injected at a
more advanced period, there evidently appear
to be fewer vessels, though it is very probable
that a fine injection may be forced into vessels
which had previously ceased to carry blood.”
In the correctness of this observation Sir B.
Brodie coincides, as well as in the opinion
“that this diminution of the number of ves-
sels, and, consequently, of the supply of blood,
is probably the proximate cause of those exfo-
liations which sometimes occur, where the
disease has existed for a considerable length of
time, especially in the smaller bones.”*
Although carious ulceration, or, as it would
be more correctly termed, absorption of bone,
is so frequently attended by the formation of
matter and abscess, yet such is by no means a

* See Lloyd on Scrofula, p. 123, and Brodie on
the Joints, last edition, p, 195,

451

necessary consequence—at least, we have ex-
amples of the removal of large portions of
bones without any such unfortunate accompa-
niment. These principally appear under two
distinct forms : one, where such absorption is
the result of inflammatory action within the
bone itself, the most familiar illustration of
which is to be found in the caries of the spine
attending on some cases of angular curvature :
the other, where the absorption has been occa-
sioned by the pressure of an aneurism, an
abscess, or other tumour in the immediate
neighbourhood.

Mr. Pott, and others who have described
this caries of the spine, mention that, at first,
the bodies of the vertebree seem to spread so
as absolutely to become larger than in a state
of health; that the ligaments are loose and
detached, and the intervertebral cartilages sepa-
rated from the bone. The first part of this
description is certainly not correct, for in all
the subjects we have had opportunities of ex-
amining, nothing like an enlargementor swelling
of the bone appeared. It must be recollected
that dissections of this disease at an early
period are rarely met with—never unless the
patient had been accidentally seized by some
mortal affection soon after the spine had been
attacked. It may, therefore, be supposed that
these early descriptions were taken from ana-
logy with what other bones suffer in scrofulous
disease, and it is well known that, until a com-
paratively recent period, it was a universally
received opinion that the heads of bones be-
came actually enlarged under similar circum-
stances.

Sir B. Brodie, who has given the clearest as
well as the most succinct description of caries
of the spine we have met with, considers that
its pathological history may be arranged under
three heads.

1. “ It has its origin in that peculiar sof-
tened and otherwise altered condition of the
bodies of the vertebre, which seems to be
connected with what is called a scrofulous state
of constitution. In these cases ulceration may
begin on any part of the surface, or even in
the centre of the bone, but in general the first
effects of it are perceptible where the interver-
tebral cartilage is connected with it and in the
intervertebral cartilage itself.” *

As this is an instance of scrofulous caries,
such as has been already noticed, it should
perhaps have come more legitimately under
consideration in that part of our article. We
prefer, however, to take a distinct and separate
view of caries of the spine, because the locality
invests the disease with some peculiarities.
For instance, this scrofulous caries is almost
invariably attended by abscess, and we find
these collections to be much larger in quantity
of contents, and, if possible, more sluggish in
approach to the surface than when situated
elsewhere. Theirexistence, therefore, may not
only not be suspected, but the symptoms occa-
sioned by them during life may be attributed
to a totally different cause. They are least

* Brodie on the Joints, p. 243.
2G 2

452

frequently met with in the neck, but when so
Situated it is easy to conceive how they may
occasion dysphagia or difficult respiration.
We have seen a case where such an abscess
occasioned symptoms resembling those of com-
pression of the brain, and we have the notes of
one in which death was produced in a very
sudden and unexpected manner, the matter
having burst into the sheath of the spinal
marrow. They may also occur in connexion
with disease of the dorsal vertebre, and within
the chest give rise to symptoms resembling the
different forms of deranged respiration—tho-
racic aneurism—and, under peculiar circum-
stances, even of empyema. Such difficulties
are now not so likely to occur, as we have
auscultation to assist the diagnosis; but we
recollect to have seen more than one case
treated as a pulmonary affection, the real nature
of which was caries of the dorsal vertebra,
complicated with abscess pressing forward
within the posterior mediastinum. Abscess in
the loins connected with diseased vertebre is
too familiar an occurrence to require any
lengthened details.

As far as our own observation can guide us,
we believe the appearance of abscess as an
accompaniment of spinal disease to be almost
always a fatal symptom; and when, in the
course of a wasting and protracted discharge,
spicule of carious bone, or portions of a sub-
stance resembling ivory or enamel are seen to
come away, the aspect of the case is still
farther formidable—very few, if any, ever
recover under such circumstances.

2. “ In other cases the vertebre retain their
natural texture and hardness, and the first
indication of the disease is ulceration of one or
more of the intervertebral cartilages, and of
the surfaces of bone with which they are con-
nected.”*

“ There is still another order of cases, but
these are of more rare occurrence, in which
the bodies of the vertebre are affected with
chronic inflammation, of which ulceration of
the intervertebral cartilages is the consequence.”

We shall now proceed to detail the results
of our own observations, in order to see how
far they coincide with those of the learned and
accurate surgeon already quoted.

In two instances we have, in the dissecting
room, seen the intervertebral substance eroded
at the anterior edge, the bodies of the adjacent
bones remaining unaltered in shape or consis-
tence, and to every appearance in a perfectly
healthy condition. These were, at the time,
regarded as specimens of the very earliest and
incipient stage of the disease, and although no
clue could be obtained as to the history of the
cases, it is worthy of remark that not a trace of
scrofulous disease could be discovered in any
other parts of the bodies.

In general, however, it is otherwise. The
body of the bone seems to be seized with
scrofulous inflammation, and the peculiar ef-
fects of this morbid action are produced within
it. It becomes softer in consistence, in conse-

* Brodie, loc. citat.

BONE, PATHOLOGICAL CONDITIONS OF.

quence of the absorption of its osseous parti
cles, and a deposition of the cheesy lymph in
its stead. At this time, although so softasto
admit of being cut with a knife, the bone ap- |
pears unaltered as to size or shape, but its
absorbents begin to act upon the ligaments and .
intervertebral cartilages, and hence is it that
the separation and ulceration of these are
amongst the earliest appearances. In many
instances the connexion between the cartilage
and bone is so much impaired, that if we 3
wanted to separate them with a knife, the former
would come off in one entire flake. The
edges then begin to be eroded and ulcerated,
as if gnawed by a mouse; and at this period
also the ligaments are often found thickened
and softened, and matted up together into a
confused and indistinct mass. The body of
the bone then becomes carious, and the ulce-
ration commences at the anterior part of it:
very rarely is the posterior layer of firm bone,
that forms the front of the canal for the spinal
marrow, affected; and never does the caries
spread to the processes. Up to this period it
may be, and often is, a specimen of purely dry
caries, being unattended by the formation of a
single drop of purulent matter.

As the disease proceeds, and the bodies of
one or more vertebrae are removed, those which
remain approximate more or less above and
below: the spinous processes project, and a
bending of the body forward is produced.
The character of this curve is influenced by
the extent of the destruction that has been
accomplished within; it is sharper and more
angular when the body of one vertebra only has
been removed; it is more sweeping and gradual
when three or four have suffered. Never, we
believe, is the angle so sharp as to permit the
denuded surfaces of the vertebre above and
below to come into actual contact, the sound
condition of the bony parietes of the spinal :
sheath effectually preventing this; and hence, ;
when recovery takes place, it is not by the 4
adhesion of these surfaces, but by the forma-
tion of a quantity of new bone which fills up
the vacant space, producing a perfect example
of true anchylosis.

The developement of such a curative pro-
cess as this is scarcely to be expected in a
scrofulous system, yet is it satisfactory to know
that even under such circumstances the case is
not utterly hopeless. We have seen repeated
instances of angular curvature without the
occurrence of abscess, in patients apparently
deeply tainted with scrofula, one of which is
so very remarkable as to deserve particular
notice, because it illustrates a mode of union —
that frequectly occurs in scrofulous cases, and
because the preparation is in existence to de-
monstrate the fact. InJuly, 1830, a wretched a
young girl was brought into the Meath hospital _
with a very acute angular curvature of the
dorsal vertebre. Almost every joint in her
body was diseased, and the knees so extensiv
that the eroded condyles of the thigh-bones
exposed, from the surface of one of which the
mud of the street was wiped away after
her admission. It need scarcely be added —

Lee ee

ae

BONE, PATHOLOGICAL CONDITIONS OF.

that her sufferings were not of long duration,
and an opportunity was speedily afforded for
examining the pathological condition of the
back. It appeared that three of the vertebre
had been engaged, the spongy portion of one
of which had been completely removed. There
was nothing like a reproduction of osseous
materia!, although the caries had long ceased,
and the spine was sufficiently strong for every
ordinary purpose of support; but the space
that had been left by the absorption of the
bone was filled up bya ligamento-cartilaginous
substance, which, attached like a new and
adventitious ligament to the vertebre above
and below, held them with a sufficient tight-
ness to prevent the smallest motion, and gave
to the entire column a tolerable degree of firm-
ness. We have also seen examples of true
bony anchylosis in patients apparently scrofu-
lous, but it seems to occur generally in males
rather than in females, and more particularly
in patients about or approaching to the age of
puberty, a period at which it is generally sup-
posed some important change takes place in
the constitution of scrofulous subjects. Where
there is no such taint, or where, as Sir B.
Brodie expresses it, the bones retain their na-
tural texture and hardness, it may be easily
conceived that a cure is effected in less time
and with less difficulty.

There is another specimen of caries or ulce-
ration of bone without the formation of matter,
occasionally observed in the neck of the thigh-
bone of very old persons, the symptoms of
which have particular relation to the hip-joint ;
we shall therefore postpone our remarks on it
until we come to discuss the pathology of
joints.

Necrosis.—There are few subjects more in-
teresting either to the pathological inquirer or
to the practical surgeon than the death of a
portion of the osseous system, and the circum-
Stances connected with this event. Neither is
there any one with respect to which the ideas
of medical men generally are less definitively
settled. Thus also some confusion has crept
into our nomenclature, and necrosis and ex-

Joliation have been often indifferently used, as
if they applied to one and the same diseased
action ; or, perhaps, to speak more correctly,
the term necrosis has been made to extend to
every case in which a bone or a portion of a
bone is deprived of vitality, no matter how
the dead material is to be removed or replaced.
According to the etymology of the term such
is in fact its true meaning; nevertheless, we
are hardy enough to dissent from this applica-
tion of the word, and to confine its use to one
form of the death of a bone, exfoliation more
properly belonging to another. And we do so

more readily because not only do these two

__ affections present different pathological pheno-

mena, but there are such practical discrepancies
between them that it is essential to every sur-
eq to have a distinct and separate notion of
each.

Exfoliation, then, expresses the death of a

_ portion of bone which is either never replaced,

or replaced by a process which is set up after

453

its death, and is analogous to mortification in
the soft parts, where the slough is thrown off,
and the consequent ulcer subsequently heals by
granulation and cicatrization.

Necrosis is the death of a bone or part of a
bone accompanied by a process of regeneration
established at a time coeval or nearly coeval
with the inflammation or accident that deprives
it of vitality. In this point of view the disease
is singular, there being nothing like or ana-
logous to it in any affection of the soft parts.

Necrosis is rarely a disease of early and
never of advanced life, being, except in cases
where it attacks the lower jaw, almost exclu-
sively confined to the period between the ages
of ten and twenty-two: exfoliation may occur
at any time, but is more likely to appear in the
adult or the aged.

Necrosis, although it may succeed to acci-
dent, as in this manner compound fractures and
other injuries are not infrequently repaired, yet
is it more generally an idiopathie disease, or
may be the sequela of continued fever; whilst
exfoliation in the great majority of instances is
the consequence of injury.

According to the acceptation in which we
employ the term, it is extremely questionable
whether necrosis is ever a disease of the flat
bones; at least, except in the instance of the
lower jaw, we have never met with an example
of the death of one of these structures accom-
panied or even followed by a regenerative pro-
cess.

As necrosis, then, presents a solitary exam-
ple of the efforts of nature in counteracting, or
rather in providing against the ravages of dis-
ease, the process by which it is accomplished
becomes an exceedingly interesting subject of
inquiry. Different opinions are entertained
upon this subject. It seems to be agreed
upon all sides that the commencement of the
disease is marked by inflammation of the bone:
at this period it is red, vascular, and receives
the tinge of coloured injections. How this in-
flammation may be caused or why it is followed
by the formation of new bone, are points not so
easily determined. Troja introduced a sharp
instrument through a bone, by which he con-
trived to destroy the internal periosteum and
marrow, and thus produced a number of cases
of necrosis, which presented the same sym-
ptoms and ran the same course as if they had
been examples of idiopathic disease. Hence it
came to be believed that the death of the inter-
nal periosteum was a necessary prelude to
necrosis, until it was observed that the parts
surrounding a bone had assumed those actions
which end in the formation of a new one before
the absolute destruction of any part of the old
one whatsoever ; and therefore that, although
the injury inflicted on the internal periosteum
might cause necrosis, yet it was only one cause,
and acted by creating inflammation within the
substance of the bone. Thus we are obliged to
return to the point from which we set out: we
know that inflammation is established within
the bone, and, coeval with this or nearly so,
that nature commences the process of repro-
duction ; but why this latter is confined to a

454

limited period of our existence, or why even
amongst young persons it may occur in one
individual and not in another, form questions
to which, in the present state of our knowledge,
we can give no answer. We are not even
agreed on the different steps of the process or
on the structure principally engaged.

It has been observed that the portion of the
bone which is to die, and for some space above
and below it, is surrounded by a dense thick-
ened mass, of rather a gelatinous character ;
that this mass, after a very short time, becomes
opaque in detached spots, and that depositions
of osseous material are found within it, so that
a case of bone may be constructed around the
original one before it actually dies, and thus
the limb never be entirely deprived of support.*
As soon as the dead bone separates from this
surrounding mass, the internal surface of this
new material becomes, under some circum-
stances, covered with a layer of lymph, and
under others with regular ossific granulations,
which gradually increase until a new bone is
formed, nearly as serviceable, though not so
symmetrical or so beautiful as the old one. It
next becomes a question, what is this gelatinous
mass, and whence is it derived? It has been
supposed that it was the periosteum of the old
bone swelled and thickened, and at the same
time softened in consistence; and this opinion
has been strengthened by Dr. Macartney,+ the
present Professor of Anatomy in the University
of Dublin, who stated that he had opportunities
of watching the progress of the disease from its
earliest periods upwards. According to this
gentleman, “ the first and most important cir-
cumstance is the change that takes place in the
organization of the periosteum; this membrane
acquires the highest degree of vascularity, be-
comes considerably thickened, soft, spongy, and
loosely adherent to the bone; the cellular sub-
stance, also, which is immediately connected
with the periosteum, suffers a similar alteration :
it puts on the appearance of being inflamed, its
vessels enlarge, lymph is shed into its inter-
Stices, and it becomes consolidated with the
periosteum.” Next, “the newly organized pe-
riosteum, which, for the sake of distinction, one
might call the vascular sheath or investment,
separates entirely from the bone, after which it
begins to remove the latter by absorption, and
during the time that this process is carrying on,
the surface of the vascular investment, which is
applied to the bone, becomes covered with
little eminences, exactly similar to the granula-
tions of a common ulcer.” To this doctrine
Mr: Russell, of Edinburgh, strongly objected.
He stated that if the osseous matter was depo-
sited between the layers of periosteum, both the
external and internal surfaces of the new de-
posit ought to be perfectly smooth, whereas the
contrary is observed—they are rough, irregular,
and one of them is covered with granulations.
He instanced cases of fracture in which, one
fragment overlapping the other, and being thus

* See Russell on Necrosis.
+ See Crowther on White Swelling.

’ Edition
1808, p. 183.

BONE, PATHOLOGICAL CONDITIONS OF.

‘more advanced period, the periosteum is |

permanently entangled, the periosteum |
the two can have no share in the reproduction,
and yet the whole is united by a cylindrica
shell of bone, on the principle of reproducti
in necrosis. It is also known that compound
fractures, where the fragments have been exten-
sively stripped of periosteum, have united in —
the same way, and the regeneration of bone, in
these instances, could not be attributed to peri-
osteum, inasmuch as that had been destroyed.
It must be owned that this is a very unusual
occurrence in compound fractures, but one sin-
gle exainple will be sufficient to fae that the
reproduction can take place independently of
the periosteum. And again, in cases where
disease has caused the sloughing and destrue-
tion of the periosteum, as for instance in deeply
seated paronychia, still reproduction is some-
times accomplished by a process resembling
necrosis. These arguments seem to be very
decisive in overturning the doctrine of the sur-
rounding shell being furmed by the periosteum,
and accordingly Russell supposed thata depo-
sition takes place from all the surrounding ‘
structures ; that it is at first gelatinous ; that it
soon assumes the appearance of cartilage; and
that at the end of twenty-four days bony specks
may be discovered within it. The external
surface of this deposit is rough, and attached to
the surrounding parts: its thickness is quite
unequal, being greater in proportion to the du-
ration of the disease, and always more so than
the bone it is destined to replace. The internal
surface, or that next the old bone, is more
sinocth, and covered either with lymph or gra-
nulations. Boyer, Meckel, Weidmann, and
other coutinental surgeons, attribute the process
nearly altogether to the periosteum, and there-
fore their opinions need not be particularly dis-
cussed ; but it is proper to mention that all the
very accurate descriptions we read, of the pro-
gress from gelatine to cartilage and from carti-
lage to bone, ust be received with the utmost
caution. Itis by no means usual to meet with
cases exemplifying these descriptions; and
amongst a considerable number of dissections
of necrosis, it will perhaps be difficult to find
one in which the existence of cartilage can be
separately and distinctly shown.

Such is an outline of the chief opinions en-
tertained on this interesting subject, and it is
probable that, to a certain extent, they are all
correct. When the periosteum has not been
removed or spoiled, there can be no doubt that
itis deeply and even principally engaged in the
se of reproduction. In the museum at

ark-street, the specimens exhibiting the earliest
period of the disease show the periosteum as
slightly thickened, smooth on its internal, bt
more rough and flocculent on its external su
face, detached from the bone, the surface
which is smooth, and scarcely appears chan
from its natural and healthy condition. .

thicker, but is not softened ; on the cont
it has nearly the firmness of ligame
there are small osseous itions |
the bone then being rough and un¢
surface and evidently having lost

BONE, PATHOLOGICAL CONDITIONS OF.

But although we concede to the periosteum the
principal office in the process of reproduction,
we can also conceive that the adjacent tissues
are also more or less engaged, for the thicken-
ing of parts is found to extend on the outside
of this membrane, and Dr. Macartney himself
speaks of the cellular tissue external to the

riosteum becoming altered and condensed.

Ow, Supposing the periosteum to be destroyed,
these structures may be capable of supplying
its place and producing the secretion of gelati-
nous substance, which is afterwards to become
bone, just as we see that if the periosteum is
torn off a bone, the adjacent tissues laid down
upon it may prevent exfoliation, and answer
every purpose of nutrition and preservation
that the original membrane did. From what-
ever source derived, this deposition becins
while yet the original bone is in a state of in-
flammation, and the part that is to die still un-
detached. If tendons or muscles are inserted
into this 2 of the bone, they, being living and
organized substances, separate from that which
is dead: but the previous deposition has ex-
tended about them, and fastened them in their
situations, and hence not only is the limb capa-
ble of support during the progress of necrosis,
but unless in exceedingly rapid, acute, and un-
favourable cases, its motions may not be very
materially impaired.

Soon after the investing shell has been form-
ed, the dead portion of the bone separates from
its attachments, and lies within its osseous
case. It is now termed the sequestrum, and
presents some remarkable and peculiar charac-
ters that distinguish it from diseased bone
otherwise circumstanced. Its extremities are
always jagged, pointed, and uneven: its mar-
row and internal periosteum have disappeared :
its length and its diameter are always much
less than ought to be anticipated from consi-
dering the size of the bone that has died ; and
its surface is uneven and marked with slight
depressions, as if part of its substance had
been taken up by the absorbents. This ap-
pearance is more distinctly observable, and the
Sequestrum is always smaller where the surface
of the new shell is covered with granulation,
than when it is only smeared over with lymph.
And here, as in other cases, it may be observed
that the existence of granulation or of lymph
on the new bone seems greatly to depend on
the free admission of air to the cavity. Where
the bone is deep-seated, as in the thigh, and
there are but a few sinuous apertures that can
scarcely render the cavity analogous to an open
sore, the surface is covered by a layer of lymph;
but where it is more superficial, as when the
shaft of the tibia has come away and left the
new osseous deposit totally uncovered, its entire
surface is seen studded over with healthy gra-
nulations, which, on passing the handle of a
scalpel over them, are found to be gritty, and
give sensible indications of containing bony

_ Matter.

From the first formation of the new deposit,
_ small holes or perforations exist in it, the edges
_ of which are bevelled down and thin, and not-
- ding that the new bone may and

455
usually does become extremely thick and
spongy, these apertures stil! remain thin: it is
through them the matter makes its way to the
surface and forms the fistulous ulcers that
attend on this disease, and are to be described
hereafter. ‘These apertures remain as long as
there isa single spicula of sequestrum within to
keep up irritation and protract the Suppuration.
After the sequestrum has completely disap-
peared, the growth of osseous material still
continues internally until the new shaft appears
one solid mass devoid of any cancellated or
medullary cavity whatever. At this period the
ulcers are healed up, and the patient enjoys a
wonderful use of his swollen and deformed
limb, but the pathological condition of the bone
is still deserving of attention. At first it is a
mass of soft and spongy texture. After the
lapse of a few years, though still clumsy in
shape and undiminished in diameter, the bone
has become much more firm and solid, and in
these respects, at least, equals the original
structure. Ata more remote period the osseous
part is wonderfully solidified, heing, in some
Instances, as firm as ivory, and a new medul-
lary cavity, with an internal periosteum, 1s
formed. When a transverse section of a tibia
so circumstanced is made, the osseous walls
are found to be hard, thick, and very firm, the
medullary cavity much narrower than in the
healthy bone, being scarcely capable of admit-
ting more than a goose-quill, and it does not
seein to be cancellated or reticulated, but merely
to consist of one continuous cell. In this state
the bone possesses nearly three times the
weight of one in the natural condition, and
when dried is of a dirty Lrown colour, never
assuming the white tint or polished appearance
of the remainder of the skeleton.

Necrosis once formed is variable in its pro-
gress and indefinite as to the tirne that may be
necessary to its completion. Sometimes the
affection of the bone is exceedingly acute, ac-
companied by external inflammation resemb-
ling phlegmonoid erysipelas: in these cases
the bone soon dies, the sequestrum separates
and protrudes very rapidly, perhaps even before
the new deposit has attained strength to sup-
port the limb, so that it is necessary to preserve
it artificially as to shape and length until the

rocess is complete. Within the last year we
ee seen a case in which, through neglect of
this precaution, the tibia is bent nearly into the
shape of the letter C. In other instances the
disease is extremely tedious, requiring years
before the sequestrum is either removed or ab-
sorbed : we possess a preparation exhibiting a
specimen of necrosis of more than six years’
duration, in which the sequestrum is of a more
than ordinary size. Between these extremes of
great rapidity and as great tediousness there is
every possible variety, and perhaps these me-
dium cases are the most unfavourable, for the
very rapid are over before the constitution is
broken down, and the very slow produce their
effects on the system so gradually as not to
make any decided or severe impression ; whilst
those which exhibit the symptoms of abscess,
with an extraneous body working to gain the

456

surface and not able to accomplish it quickly,
occasion much suffering, and if there is ever
danger to life or limb from the disease, such
cases are most likely to produce it.

The sequestrum or dead bone is disposed of
either by presenting externally and permitting
of its removai by the process of ulceration or
by manual operation, or else it is never seen,
and is entirely carried off by the absorbent
vessels. Mr. Russell accounted for the disap-
pearance of the sequestrum in a very unsatis-
factory manner. He considered the dissolution
of the dead bone to be “ greatly accelerated by
the solvent power of the purulent matter,” a
property, the existence of which in pus both
observation and experiment render question-
able: and when thus macerated, he conceived
it to be prepared to be removed by absorption
or washed out by the discharge of the matter.
But, if the surfaces of a sequestrum are exa-
mined, that which is next to the granulations
of the new bone will be found to be irregularly
marked and indented, as if by the action of the
mouths of the absorbents, whilst the other is
comparatively smooth ; and as every part ex-
posed to the action of the fluid should suffer
equally if the removal of the osseous particles
was effected by maceration, there are strong
reasons for believing that the disappearance of
the sequestrum depends not on any power
chemical or mechanical, but on some vital pro-
cess, and therefore probably on the action of
the absorbents.

When the sequestrum presents externally,
either one end of the bone (almost always the
Superior one) protrudes through the soft parts
and remains there dry, hard, and dead fora
longer or shorter time, until it becomes de-
tached by the slow process of nature, or is
separated by a surgical operation; or else the
middle of it presents, and can be seen or felt
through an.aperture in the surrounding new
bone whilst its extremities are confined. In
either case the process of removal is extremely
tedious. When the end presents, it is gene-
rally moveable, and seems as if very little
force would be sufficient to detach it altogether ;
yet if an attempt is made to pull it away, it is
by no means easily accomplished, and a con-
siderable time elapses between the first pro-
trusion and its final and complete separation.
When the middle presents, the process is still
more protracted. All bones do not seem equally
liable to necrosis. Perhaps the tibia is as fre-
- quently attacked as all the other bones of the
skeleton taken together; next in frequency is
the humerus, the bones of the fore-arm, the
thigh, the clavicle, and lastly the lower jaw.

Thus far, it will be seen that we have con-
sidered necrosis as a disease, distinct and dif-
ferent from every other affection of the bones
whatever, and that its chief and most marked
characteristic is the process of regeneration.
Regarded in this point of view, it is as much
and even more an action of health than of dis-
ease, and it can easily be understood why the
constitution suffers so little, why the hectic
fever is of so mild and mitigated a form, and
why in a simple and uncomplicated case re-

BONE, PATHOLOGICAL CONDITIONS OF.

covery is nearly certain. It is also evid
this disease will not be ei to occur it
constitution contaminated with syphilis, se
fula, scurvy or any of those other vices whi ‘
the continental surgeons not only think itmay =
be united with, but which they adduce as its = ¢
occasional exciting causes. Doubtless, if the
death of a bone from any cause or under any _
circumstances—if caries, exfoliation, and other
such destructive maladies are to be included as
species under the generic name of necrosis,
such affections may not be inconsistent with
the existence of any poison or any taint; but
if the idea of a process of reproduction co-
existent with that of disease must be admitted
as appertaining to this affection, it will be im-
possible to recognise scrofula or syphilis as
connected with it in the remotest possible de-
gree, Perhaps we shall incur censure for thus
attempting to limit the signification of the
term, but it has been observed that the nomen- \
clature of surgical pathology is too loose and
undefined, and in no instance is the remark
more applicable than with reference to the dis- —
eases of the osseous system; and again, patho-
logy to be useful must be practical, and we can
by no means assimilate caries which is so des-
tructive of the limb or fatal to life—or exfo-
liation, which is always attended with loss of
substance—with necrosis, the essential cha-
racter of which is a process of reproduction,
and its natural termination recovery.

In attempting to describe, or even to arrange
the remaining diseases of the osseous system,
the pathologist has to encounter difficulties al-
most insurmountable. Some of these are na-
tural to and inseparable from the subject, as
1st, the depth at which a bone may be situated
will render it dificult to discover a change of
shape or size, much more to ascertain an altera-
tion of structure. 2d. The bones do not al-
ways exhibit a very active sensibility; when
attacked by chronic forms of disease, they do
not cause very great pain, and consequently
the evil may be well established and irreme-
diable before the patient is fully sensible of his
condition. 3d. These affections are not fatal
at an early period ; they run a long and tedious
course before they destroy life or render the
removal of the limb indispensible. And hence
in any individual case it may be difficult to
learn even the early history or commencing
symptoms, much more the nature of that pecu-
liarity of constitution that disposes to these
diseases, or the first changes that take place
from a healthy to a morbid structure. Little,
indeed, can be ascertained with certainty as —
to the nat_re of osseous tumours until the part —
has been removed, and then the information —
comes too late for any useful purpose. Anott
source of embarrassment exists in a want of a
cordance as to the nomenclature of these affec-
tions. One surgeon calls that exostosis which
another has named osteo-sarcoma, and a third
has designated as cellular exostosis an af
which he himself in another place has
spina ventosa. In order, in the prese
stance, to avoid similar confusion, we
endeavour to construct an arrangement

BONE, PATHOLOGICAL CONDITIONS OF.

shall give to each class of disease its own ge-
neric term; and although occasionally such
deviations from the usual operations of nature
will present themselves to the pathologist as to
baffle all his attempts at classification, still we
believe such a foundation as we allude to will
be eminently useful, whatever superstructure
may be raised upon it.

Spina ventosa.—In our museums of morbid
anatomy, there is no want of specimens exhi-
biting the separation, or rather expansion of
the solid walls of a bone, leaving one or more
cavities within it ; these cavities having during
the patient’s life been filled with a secretion that
presents considerable variety in different cases,
sometimes possessing a moderate degree of
firmness and consistency, but more frequently
consisting of a fluid of a serous character and
reddish colour. This is the disease to which
we apply the name of spina ventosa in contra-
distinction to abscess within a bone, from which
it differs in its extremely chronic nature and
tedious progress ; in its not containing purulent
matter; in its having no tendency to burst into
any contiguous joint; and (until at a very ad-
vanced period) in its not being complicated
with caries.* Boyer divides this disease into
two species, one of which is peculiar to chil-
dren, and continues to the age of puberty; the
other, the spina ventosa of adults, which ex-
hibits the characteristic features of the disease
more perfectly.

It is, indeed, ditficult to separate the first-
mentioned of these affections from our com-
monly-received notions of caries, and in the
various instances we have seen we have always
regarded them as such. Boyer attributes it to
the influence of a scrofulous taint within the
system, and says that it attacks the metacar-
pus, the metatarsus, and the phalanges. It
commences and continues for a length of time
either without pain or with very trivial suffer-
ing; the tumefaction of the parts is moderate,
their motions scarcely interfered with, and re-
covery finally takes place about the age of pu-
berty by a species of necrosis. Its course is
thus described: “ The progress of the disease
and the distension the soft parts undergo, cause
them to ulcerate at a spot always corresponding
to some aperture in the osseous cylinder, and

mitting the introduction of a probe within
its cavity. The external aperture becomes
fistulous, and for a Jong time discharges a
moderate quantity of ill-digested serous matter.
The part, however, remains indolent, the con-
stitution does not suffer, and if the patient can
thus attain that epoch of life at which nature
commonly can struggle with success against
scrofula, this form of spina ventosa may be
cured by necrosis of a part of the spoiled bone.
Then the sequestrum is detached, the re-
mainder of the osseous parts subside, resolu-
tion is established, and the disease ends by a
deep, adherent, and deformed cicatrix.” We
have not met with the affection as here described
—we have never seen any thing like the rege-

neration of a bone thus lost, nor can we con-

* Dict. des Sciences Médicales, tom. lii. p. 311.

457

ceive necrosis, which is essentially a reproduc-
tive process, to be in anywise allied to or con-
nected with scrofula; we therefore still regard
this disease, which after all is not very frequent
of occurrence in these countries, as a modifica-
tion of caries.

“The other species, fortunately more rare
but much more serious, most frequently attacks
adult persons, and affects the extremities of the
long and cylindrical bones of the limbs.” Its
exciting cause seems to be involved in utter
obscurity, nothing being known with certainty
concerning it. Very often the patient traces it
to the receipt of some injury, bnt it occurs so
frequently without any such provocation, that
it must be considered as an idiopathic disease.
It is found most frequently, as Boyer has re-
marked, in the long bones, where the medullary
cavity is best developed, but it is seen in the
flat bones also, and in so many instances in the
lower jaw as to render it an object of attention
with reference to this bone alone. Its com-
mencement has no characteristic by which it
can with certainty be known, and its progress
is equally variable, being generally slow, but
sometimes remarkably rapid. It commences
with pain, occasionally deep and dull, occa-
sionally severe to excess, either when its pro-
gress is rapid, or it presses on some sensible or
important part. This pain, with very few ex-
ceptions, precedes the swelling, and when the
disease attacks the lower jaw is almost con-
stantly mistaken for common tooth-ache—a
mistake that leads to the extraction of one or
more of the teeth and the consequent exacerba-
tion of morbid action. The tumour seems to
engage the entire circumference of the bone, if
it be a round one; if flat, the swelling is more
oval, and sometimes it is irregular and lobula-
ted. It is hard, firm, unyielding, and incom-
pressible: pressure on it does not occasion an
aggravation of pain, unless it shall have hap-
pened that the periosteum is inflamed, when
of course the smallest pressure will occasion
suffering. In the commencement it bears a
strong resemblance to necrosis of the long bone,
except in not being preceded or accompanied
by fever, and in not being so painful or so
rapid in its progress. In the flat bone it has a
greater likeness to osteo-sarcoma, from which
it is so difficult to distinguish it that many
cases of spina ventosa have been operated on
and removed as examples of the other disease.
Nevertheless at a more advanced period the
diagnosis is more easy, for spina ventosa does
not reach the great, or rather the illimitable size
to which osteo-sarcoma may attain.

In a pathological point of view, spina ven-
tosa should not be considered as a malignant
disease : it often endures for a length of time
or during life without engaging adjoining
Structures or contaminating the constitution,
and if removed by operation it does not recur
in another place or seize on some other bone.
It is, moreover, not infrequently capable of
relief or even of cure by the simple operation
of exposing the cavity and evacuating its con-
tents We have at this moment before us the
details of a case in which the patient referred a

458

spina ventosa of the lower jaw to a blow re-
ceived forty-one years previously, during the
last twelve of which the tumour had been
opened or given way spontaneously three seve-
ral times. In hospital it was punctured through
the mouth, and found to consist of three dis-
tinct cells, each containing its own collection
of a fluid of the consistence of oil, varying from
a straw colour to that of coffee, the darkest
being lodged within the largest cell. This
patient, though at the advanced age of sixty-
seven, was relieved by the operation, and left
the hospital convalescent. If, however, by the
term malignant is meant a disease that may
prove destructive of life or limb, spina ventosa
can occasionally lay claim to the title. For it
sometimes happens that small dark red or pur-
ple elevations appear on the surface of the skin,
which soon ulcerate and burst, discharging a
quantity at first of the material contained within
the bone, the character of which subsequently
alters into a brown, unhealthy, fetid, and often
putrid sanies. This ulceration is much more
likely to take place when the surface of the
tumour is uneven and lobulated, and at this
period the disease in appearance bears no very
faint resemblance to fungus hematodes. The
external sores next become fistulous and fun-
goid; they lead down to the cavity or cavities
within the bone, and the patient, worn and
wasted by an ill-formed irritative hectic fever,
sinks exhausted and dies.

Boyer* in his description recognizes these
two forms of spina ventosa. ‘ Sometimes,”
says this author, “ having attained a size dou-
ble or triple that of the natural dimension of
the bone, the tumour ceases to make further
progress: it no longer causes pain; it does not
interfere with the motions of the part, but re-
mains stationary, and continues thus during
life, without any alteration of the soft parts,
which accustom themselves by degrees to the
State of distension in which they are placed.
But much more commonly it continues to in-
crease, until it slowly arrives at an enormous
size, still preserving its inequalities of surface
or acquiring new ones.” Having proceeded to
the period of ulceration, the conclusion of the
case is thus delineated. “ Arrived at this
point, the local disease exercises a baneful in-
fluence on the constitution of the patient: the
edges of the fistulous apertures become de-
pressed and inverted towards the interior of the
tumour ; the discharge becomes every day more
copious and more fetid; the fever which ap-
pears commonly at the period of ulceration, but
which at first is intermittent and irregular,
comes at last to be continued, and assumes the
character of hectic: the pains are unceasing,
and sometimes intolerable; sleep and appetite
are deranged or lost; consumption cnanies
itself, and the patient dies exhausted and worn
out.” ©

Other authors, however, have considered
spina ventosa in all its forms as a malignant
disease. Such must have been the opinion of

* Loc. citat.

BONE, PATHOLOGICAL CONDITIONS OF.

a ie
- 4

Mr. B. Bell,* of Edinburgh, not only from his .
descriptions, but from the practice he incul-

cates. “ The treatment,” he says, “of spma
* . ~~ b a ¥
ventosa is very simple, as the surgeon, when he =
is insured of its existence, must at once have
recourse to the amputating knife. Ifthe dis-
ease is seated in the bones of the metacarpus
or metatarsus, as is generally the case in child-
hood, they should be removed at the articula-
tions. If it has attacked the tibia and fibula,
or radius and ulna, the amputation may be
performed either at the knee or elbow, or a short
way above these joints. The general rule to be
observed is, that the entire bone in which the
disease has its seat should be removed.”

The morbid anatomy of spina ventosa throws
but imperfect light on its pathology, principally
because the first and early changes induced
the disease are wholly unobserved, and there-
fore are we ignorant both of the peculiarity of
constitution that disposes to it, and of the local
alterations that are first developed. Even at a
more advanced period, when an opportunity is
afforded of examining the part after death or
removal, there is no striking uniformity of ap-
pearance. The bone itself, as Boyer remarks,
seldom seems to have suffered any actual loss
of substance: on the contrary, it often appears
rather to have gained in weight, the walls ex-
panding and becoming thinner in proportion as
the cavity within increases in size. As to the
number, size, and shape of these cells, there is
an infinite variety as well as in the appearance
of the surface, which may be smooth, irregular,
or lobulated, and in the character of the mem-
brane lining the cells and the material secreted
by it. There is in the museum of the Anato-
mical School, Park-street, Dublin, a very curi-
ous specimen, exhibiting a perfect bony cyst
developed within a spina ventosa of the supe-
rior maxilla, and completely contained within
the expanded walls of the bone. It is a very
remarkable circumstance conhected with these
alterations of structure, that although they usu-
ally commence near the extremities of the long
bones, they never attack the joints, and conse-
quently the motions of the adjacent articulation
may be but slightly impaired, even although
the size of the tumour may be such as to inter-
fere with the natural shape of the joint, and
render its usual appearance obscure and indis-
tinct.

Exostosis—We employ this term to indicate
certain tumours growing from the outer sur-
face, or rather the external structure of a bone,
in the production of which neither the medul-
lary substance within nor the periosteum with-
out have any participation. And although our
notions of the nature of the disease may not
be pee correct, and our descriptions lame _
and incomplete, we still prefer this arrange- —
ment in order to separate the disease under —
consideration from spina ventosa on the one
hand, and osteo-sarcoma on the other. It will
be necessary also to distinguish it from nodes —
and some other affections of the periosteum, in ~

eae

ee
oa

* Treatise on Diseases of the Bones, by Benjam: in 3 |
Bell, edit. 1828, aby Benieeee,

BONE, PATHOLOGICAL CONDITIONS OF.

which a deposit is found between it and the
bone, or between the lamine of this membrane.
Exostosis, then, may consist of different struc-
tures—of cartilage alone—of cartilage mixed
with some material resembling ligament—of
cartilage mixed with osseous structure, which is
by far most frequent of occurrence—of pure
bone—and lastly, of a much harder, firmer,
and closer substance, nearly resembling ivory.
It may attack any bone whether flat or round,
and may be found in more than one bone at a
time: perhaps the femur and the tibia are most
frequently engaged.

_ Like most other affections of the osseous
system, the causes that lead to the production
of this disease are involved in the greatest
obscurity. Unquestionably they sometimes
appear as the results of accident, but then,
when other and more severe injuries constantly
occur without inducing such a consequence,
the unavoidable conclusion must be that some
peculiarity of constitution predisposing to the
disease exists in the individuals who suffer
from it. .Exostosis has been seen, though not
frequently, at a very early period of life; it
has occurred idiopathically and attacked several
bones in the same individual at the same time ;
after complete removal it has grown again with
an inveterate pertinacity, and we have seen it
in two or more individuals of the same family.
Boyer* considers the venereal poison to be the
most common cause of exostosis, scrofula to
have but little connexion with it, and scurvy
still less. Other French writerst take a more
extensive range, and adduce as causes, accident,
cutaneous affections, scrofula, scurvy, cancer,
and venereal. We cannot coincide with any
of these opinions. Scrofula, when it attacks a
bone, produces a destructive caries, and not an
adventitious growth; scurvy, a softness or
brittleness of bone. If there is any idiopathic
disease of bone bearing the smallest resem-
blance to cancer, it is osteo-sarcoma, and vene-
real or even mercury we suspect to have a
closer connexion with caries than exostosis.

In every form of exostosis, no matter from
what cause proceeding, (and we have seen that
its exciting causes are sufficiently obscure,) the
surface of the bone and its substance to some
depth become altered into a structure nearly
resembling that of the morbid growth. Patho-
logists are not agreed as to whether this altera-
tion should be attributed in the first instance
to an inflammatory process within the perios-
teum or the bone itself. Mr.Crampton{ makes
the terminations (as they are technically called)
of chronic inflammation of the periosteum to
consist in cartilaginous thickening of the mem-
brane, absorption of the subjacent bone, or
the deposition of an undue quantity of bony
matter upon its surface, the first and last of
which are evidently forms of exostosis. How-
ever, leaving this part of the subject, which
after all is not of much practical importance,
still unsettled, it may be remarked that whether

* Traité des Maladies Chirurgicales, tom. iii. p.

+ Dict, des Sciences Médicales, art. Exostose.
t Dub. Hosp. Rep, vol. ii. p. 433

459

the morbid action commences in the bone or
not, this latter structure is always extensively
engaged. Exostosis is seldom to be met with
like a circumscribed tumour in the soft parts
connected by a narrow neck or bounded by a
well-defined base; on the contrary, the bone
forms a considerable portion of the swelling,
which generally seems to spring gradually from
an extended portion of its surface.

The symptoms of exostosis may be arranged
into those produced by the inflammatory or
other diseased action within the bone or perios-
teum, and those occasioned by the pressure of
the tumour on the adjacent organs. In general
it is said not to be very painful nor very sen-
sitive to the touch, but this opinion must be
received with great limitation. We have wit-
nessed the case of a young gentleman who had
exostosis on the front of both tibie. Here was
neither nerve to be compressed nor muscle to
be interfered with, yet the pain was so great
that he insisted on their removal. The part
was as hard and firm as ivory, and removed
by the mallet and chisel. His sufferings were
extreme: he was subsequently attacked with
erysipelas, and his life brought into extreme
danger, yet did he not regret his pain and the
risk he ran when considered as the price of the
relief he had obtained. The pain in this case
could not be regarded as the result of pressure
on any very sensible structure.

However, the situation of the tumour may
not only occasion a great aggravation of suffer-
ing, but be the cause of very formidable occur-
rences. We have seen a very small exostosis, not
larger than half a marble, prove the apparently
exciting cause of epilepsy, which for years
embittered the patient’s existence, and at length
brought it to a termination. Indeed, it can
scarcely be necessary to adduce instances in
order to prove that morbid growths from the
internal table of the skull may prove detrimen-
tal or even destructive in a variety of ways.
Such growths from the bottom of the orbit very
generally destroy vision by protruding the eye
from its socket; from the maxille they may
interfere with respiration or deglutition; and
in any situation where there are muscles, they
must more or less change their direction or
otherwise impair their motions. But beyond
this they cannot be considered as malignant—
they do not involve adjacent structures in a
disease similar to themselves, they do not
ulcerate, neither do they contaminate the sys-
tem through the medium of the absorbents.
The vascular organization of an exostosis seems
to be inferior to that of the bone from which
it springs, and to the healthy structures whether
bone or cartilage that it may appear to resem-
ble; its growth is therefore in general slow and
its size moderate ; but its increase is progressive,
and there is no limit to the size it may ulti-
mately attain, in this respect differing from the
node, which soon attains its proper dimensions
and does not increase subsequently. The same
deficiency of organization causes it to endure
an attack of inflammation but badly, and
therefore, when subjected to any irritation or
even exposed to the influence of the atmos-

460

phere by the ulceration of the superincumbent
tissues, it is prone to fall into mortification,
which is one of the methods by which a natural
cure may be accomplished. Not very long
since a man was operated on in the Meath
Hospital for the removal of an ivory-like exos-
tosis from the tibia, but the tumour was so
hard as to resist chisel and mallet and every
instrument that could be employed, and, finally,
the operation was abandoned; yet was the
case ultimately successful, for the exposed
tumour sloughed, exfoliated, and the patient
left the hospital perfectly well.

It is remarkable that if the exostosis has
heen removed by operation, the same degree of
certainty as to its not returning does not exist
as when it has thus sloughed away. On the
contrary, when the tumour has been completely
extirpated and only the sound part of the bone
left, a new growth is often formed with so
much certainty and rapidity as to justify the
expression we have already used, of its “ grow-
ing again with an inveterate pertinacity.”. On
this subject we recollect a story (told, we be-
lieve, by Bell) which might be considered as
ludicrous if it was not but too instructive. A
dancing-master had exostosis on both tibie ;
they gave him no inconvenience, but the de-
formity was intolerable to his eyes, and he
thought it interfered with his popularity and
therefore with his profits. He persuaded a
surgeon to lay them bare and scrape them
down to his ideas of genteel proportion, but
unfortunately the surgeon forgot that bones
could granulate and grow. They did so in
this case, and after a long confinement and
much suffering the last condition of the patient
was worse than the first—the deformity was
much increased.

We distinguish a node from a truly exostotic
growth by the rapidity of its formation, by its
becoming stationary when it has been formed,
whereas the increase of exostosis is progressive
and may be unlimited; by its being exquisitely
tender to the touch; its being subject to noc-
turnal exacerbations, and by its capability of
being relieved or removed by medicine in a
great number of instances. When composed
of osseous material alone, the almost stony
hardness of an exostosis will serve to distin-
guish it, and when of cartilage, it is lobulated
or nodulated on its surface, which is never the
case with respect to nodes.

There is a fungoid disease of the periosteum
which, under particular circumstances, may be
mistaken for exostosis, an error which we have
witnessed, and which might be attended with
serious consequences. It is fortunately of very
rare occurrence, and as far as we know has not
been hitherto described. In the four speci-
mens which have fallen within our observation,
its situation has been in the periosteum of the
tibia.

During life, when covered by a dense and
resisting fascia, the tumour is very hard, its
growth slow, and not attended with much pain;
neither is the use of the limb much impaired,
as we have known a patient with this disease
travel on foot a distance of six miles to the

BONE, PATHOLOGICAL CONDITIONS OF. :
hospital. When not so restrained, its growth

is more rapid: it is softer to the feel, and has
most of the external characters of mali

fungus. Frequently its surface is lobulated or
otherwise uneven, when it very much resembles
exostosis. When the skin gives way and ulce-
rates, or if the tumour is unfortunately cut into,
a bleeding fungus protrudes, that runs rapidly
into a gangrene, which involves the adjacent
parts; and if the limb is not speedily removed,
the patient dies.

When examined after death or removal, the
tumour is found to be situated within the
lamine of the periosteum. ‘There is a speci-
men in the museum of the school in Park-street,
in which the membrane may be seen as if split,
one layer passing in front of the diseased mass,
and another still more distinctly, behind, be-
tween it and the bone. The consistence of the
tumour is tolerably solid and firm, but not so
solid as cartilage; its colour is white or gray,
and its vascular organization apparently very
deficient. This latter circumstance is very re-
markable, for in some instances these tumours
exhibit a pulsatility scarcely inferior to that of
an aneurism, a symptom that may render dia-
gnosis extremely difficult, and which cannot be
explained by any post-mortem examination.
The substance of the bone beneath the tumour
is always removed by absorption to a consider-
able depth.

Osteo-sarcoma.—This disease, as its name im-
plies, is a degeneration of the bone into a sub-
stance of a softer consistence, not, however,
resembling flesh; or rather it is an alteration of
structure accompanied by a deposition of new
material, and therefore attended by tumefaction
to a greater or less extent. As such, it is evidently
irremediable except by the knife, and if there
is a disease of the osseous system to which the
term malignant can be applied, it certainly is
this. Its malignancy, however, has no resem-
blance to that of cancer or fungus hematodes,
although like the latter it very frequently attacks
persons in the earlier periods of life; but it
does not involve adjacent structures in a disease
similar to itself, neither does it contaminate the
system through the medium of absorption. The
most terrific feature in its character is its ten-
dency to recur after its removal from one situa-
tion, being in this respect more formidable than
cancer, which is, in many instances, at first but
a purely local disease, and may be extirpated
with complete success. This predisposition to
the disease is evidently constitutional, but as
we are totally ignorant of the circumstances
that conduce to it, and will probably remain
SO, it is wholly uncontrollable by medicine or
medical treatment.

This disease may possibly affect persons at

every period of life, although we have not seen — 4

it in the aged. In children, particularly about

the fingers, the wrists, the fore-arm, &c. nodu-—
lated swellings are frequently met with of a
large size and firm consistence, which go on —
progressively increasing until they arrive ata
destructive termination to be described here-
On examination a tumour is found, the _

after.
external surface of which is bone, as thin, it may

at ae * Se

>

| le Bi nh ind
4 y ‘

BONE, PATHOLOGICAL CONDITIONS OF.

be, as paper, and in some spots nearly entirely
absorbed evidently shewing that the morbid
action had commenced and increased from
within ; the substance of this newly-formed mass
being neither cartilage nor ligament, but per-
haps something between both, and yet not so
entirely so as to deserve the name of ligamento-
cartilaginous, or to be likened to any natural
animal product whatever. It has been de-
scribed by Bell as a substance much resembling
callus.* Again, in another specimen as it ap-
pears in the adult, (in the lower jaw for in-
stance,) the part of the bone in which the dis-
ease commenced is completely spoiled and
changed into a mass of this new material, assu-
ming a rotund tuberculated appearance. From
thence downwards, towards the spot where the
bone is not spoiled, there is an admixture of
this new material with gritty particles of bone
generally disposed in a radiated form; the en-
tire containing cells filled here and there with a
dark-coloured fluid, and traversed throughout
by a foul and fetid ulceration. But osteo-sar-
comatous tumours, although generally consist-
ing of this firm material, are by no means so
invariably. In one remarkable instance in
which the disease occupied the femur, a vertical
section of the inferior end, which was mon-
strously enlarged, exhibited a mass of much
softer consistence, and cellulated or porous.
Its colour was a mottled dark brown, and it re-
sembled nothing so much as a dirty sponge
that had been soaked in blood and matter.
Sometimes the tumour is so soft as almost to
resemble brain: sometimes there are cysts con-
taining fluid like blood: in the long bones there
is constantly a fracture in the centre of the tu-
mour, or if the swelling occupies the shaft, the
articulating surfaces are broken from it.¢ Very
often this fracture is, or seems to be, the com-
mencement of the disease.

We collect from these observations and dis-
sections that osteo-sarcoma, as we understand
the term, consists in a morbid alteration inte-
resting the entire structure of a bone; com-
mencing in its interior, and incapable of re-
medy or removal unless by amputation. We
have already stated that its chief malignancy
consisted in some constitutional predisposition
which originally led to its formation, and in-
duces a recurrence of it in some other situation
after removal, and we wish to examine into the
correctness of this opinion in order to separate
it from cancer and fungus hematodes, because
some diversity of opinion obtains on this part
of the subject, which after all is the only one of
practical importance. Boyer,{ who considers
malignancy as constituting the very essence of
the disease, nevertheless recognizes two species.
“ In one, the osteo-sarcoma is propagated by
the continuity of some cancerous affection,
which had commenced in the adjacent soft
parts, as is seen, for example, in the bones

* See Bell’s Principles of Surgery, 4to edition,
vol. iii. part 1.
+ We have taken the above descriptions entirely

from preparations in the school of Park-street,
Dublin.

+ Traité des Maladies Chirurgicales, tom. iii,

461

which form the walls of the nasal fosse, and
more particularly in the superior maxilla when
they become spoiled as the result of a hard
and cancerous polypus, which had previously
existed fora long time insulated, and without
any other local affection. In the second species
the bone is the original seat of the disease, its
own proper tissue is degenerated, and the sur-
rounding soft parts only partake of the same
species of alteration consecutively and in a
secondary manner.” Dupuytren,* in describ-
ing the disease as it attacks the lower jaw,
offers pretty nearly a similar opinion. If, says
he, the osteo-sarcoma is primitive, it remains a
long time confined to the bone, and may ac-
quire a very considerable volume before the
lips and cheeks are affected. It then presents
itself under two principal forms: in the one,
the disease consists in cancerous fungi, which
spring from the substance of the bone, within
which the disease is often superficial, that is, it
may only affect the alveolar edge or the surface,
the body of the bone remaining without any
enlargement, and particularly its base continu-
ing sound. The second form is that in which
the disease commences in the centre of the
bone, which becomes fleshy, and swells through-
out its entire thickness. Most tumours of this
description acquire a considerable size, and oc-
casion a most repulsive deformity. The teeth,
loosened and displaced, appear implanted here
and there in the substance of the bone. It is
impossible to close the jaws. The lips, dis-
tended, thinned, and closely applied to the
tumour, no longer retain the saliva, which
trickles off continually. It is, however, worthy
of remark that these tumours, or at least many
of them, are slow to ulcerate or pass into the
condition of cancer. Sir A. Coopert has evi-
dently made a similar division of osteo-sarco-
matous tumours, and described them with his
accustomed accuracy and clearness, but under
the names of cartilaginous and fungous exosto-
sis. Mr. Crampton,f in his paper on osteo-
sarcoma, also divides it into two species, the
“ mild and the malignant,” stating, at the same
time, that the nature of either previous to dis-
section after removal or after death is involved
in the greatest obscurity. He considers the
encysted condition of the tumour, its lying in
a bed of cellular tissue unconnected with the
surrounding parts, as indicative of mildness:
the characters of the malignant, as laid down
by him, are evidently those of genuine carci-
noma. ‘ The soft bleeding fungus, which
makes its way through the integuments before
the tumour has acquired any very considerable
size ; the profuse and peculiarly fetid discharge,
slightly tinged with the red particles of the
blood ; the tubercles of a purple colour on the
surrounding skin, which adheres firmly to the
subjacent tumour; the pain, and above all the
altered health, sufficiently point out the malig-
nant character of the disease.”

We have thus laid before our readers the

* Legons Orales, tom. iv. p. 636.
+ Cooper and Travers’s Surgical Essays.
¢{ Dub. Hosp. Reports, vol. iv.

462

opinions of the highest and most respectable
authorities, although we cannot coincide with
them in classing cancer as a species of osteo-
sarcoma. Pathologically they are distinct and
different diseases, appearing in patients of dif-
ferent ages, habits, and conditions of health,
and exhibiting totally different phenomena ;
and practically they are not alike, for it would
be as insane to attempt the removal of a bone
contaminated by an adjacent cancer, as it
would be cruel to refuse the chance of an ope-
ration to one afflicted with true osteo-sarcoma.
The disease is only malignant in its tendency
to re-appear, nor can it be previously ascer-
tained by the symptoms, or subsequently by
examination of the tumour, whether it is likely
to show this disposition or not. Those nodu-
lated tuinours that occur on the fingers and
wrists of children, and which are so admirably
described and delineated by Bell,* almost in-
variably reappear in some other situation after
removal. ‘This we have seen remarkably ex-
emplified im the case of a little girl who was
admitted into hospital with the two fore-fingers
and thumb affected with this disease: they
were amputated, but in nine weeks afterwards
both the radius and ulna were attacked, and
the arm was cut off. In seven weeks both
clavicles were engaged, and the little patient
was sent to the country, from which she never
returned. Besides the development at an early
age, a rapidity of growth, accompanied by in-
tensity of pain, is considered as indicative of a
most unfavourable disposition in the system.
Yet is the contrary no assurance of safety, for
we have seen a case in which the disease had
lasted for five years and without much suffer-
ing, return after removal, and destroy the pa-
tient in less than twelve months. In general,
however, the remark seems to be grounded on
experience. The presence of a deep and foul
ulceration within the tumour is rather unpro-
mising: in Mr. Cusack’s six cases of excision
of the lower jaw, the disease returned in one
only, and in that this kind of ulcer had pre-
viously existed. It may, too, be laid down as
an unvarying rule that the secondary appear-
ance of osteo-sarcoma is more painful and
more rapid in its progress than in its first and
original attack. It is uniformly fatal.

The first approaches of osteo-sarcoma are
usually insidious, and as it is in general not a
very painful affection, it may (particularly in
children) escape observation at its very earliest
periods. Any bone may be attacked by it, but
in the adult it is more frequently situated in
the spongy extremities of the long bones and in
the lower jaw, whilst the phalanges, carpal and
metacarpal bones, the radius, the ulna, and the
clavicle furnish the best and most frequent spe-
cimens in the younger subject. It occurs often
idiopathically, and on the other hand it occa-
sionally follows or seems to follow a fracture
or other injury, as if the disposition existed in
the system, and only required some stimulus
to direct it to any one situation. It commences
usually by a small, firm, immovable tubercular-

* Loc. citat.

BONE, PATHOLOGICAL CONDITIONS OF.

like tumour appearing to spring from some p
of the bone: soon after another of these a
make its appearance, but these, in the first 05 :
stance, are free from pain and insensible to
pressure. As it increases, the pain assumes a
dull and aching character, in the jaw frequently =
mistaken for tooth-ache, in other bones for
rheuinatism. The degree of suffering, however,
is not a very strong characteristic, for it wilk 9
depend on the rapidity of growth, the disten-
sion suffered, the sensibility of the parts com-
pressed, and a number of other circumstances
too obvious to require detail. In ordinary
cases, it has been remarked that the pain ob-
serves a more than progressive increase with the
size of the tumour, particularly if its growth has
been accelerated by any accidental injury. In
the advanced stages it is always severe, and
in some instances dreadful. In one of Bell’s
cases, it is stated that there was no hour of the
night or day in which the patient’s wild cries
could not be heard miles off. In most in-
stances the sufferer is completely deprived of
sleep, and in some he complains of nocturnal
exacerbations.

Once formed, it grows with greater or less
rapidity, often appearing stationary for some
time, and then suddenly and quickly increasing :
sometimes, on the contrary, it increases rapidly
from the commencement, and we have removed
an osteo-sarcoma of the lower jaw, which at-
tained to the enormous weight of 4 lbs. 1 oz.
avoirdupoise in the short space of eight months.
Whilst the tumour is comparatively small, the
skin is pale and glassy and stretched, and blue
veins are seen meandering on its surface: when
large, its colour is dark red, verging to purple,
and multitudes of these little veins appear upon
it. It is, generally, firm to the touch, solid
aud heavy; but occasionally an examination
with the fingers discovers the osseous covering
of the tumour to be very thin, and it yields on
pressure with a peculiar sensation of elasticity,
such as one might conceive parchment to con-
vey if not stretched very tightly. At length it
gives way, and a foul ulcer is formed, dis-
charging an unhealthy fetid pus, often mixed
with blood. The character usually attributed
to this ulceration is fungoid, but we have never
seen it thus. It commences generally in the
centre of the tumour by a slough, and gradually
inakes its way outwards to burst by two or
three apertures, and we have seen an immense
osteo-sarcoma of the lower jaw completely tra-
versed by ulceration, one opening being in the
mouth and the other at the inferior and most
depending part of the tumour. These ulcers —
are usually hollow, attended with loss of sub-—
stance, and we have not observed one that
could have been easily mistaken for fungus
hematodes. my

Independent of any malignancy inherent in
the tumour, it is evident that osteo-sarcoma may
destroy life by being so situated as to compres
some important or even vital organ, more ]
ticularly if such situation precludes the pe
lity of removal by a surgical operation. |
for instance, was Mr. Crampton’s case, in 1
the diseased growth sprung from the roof ¢

BONE, PATHOLOGICAL CONDITIONS OF.

- orbit, projecting forwards on the eye-ball and

backwards on the brain, both of which organs
it must have destructively compressed.* We
have seen an osteo-sarcoma of the lower jaw in
a young boy occasion death by suffocation ; and
another in a young female impede deglutition
so entirely that she died or seemed to have
died of actual starvation. This, however, was
at a period before an operation for the removal
of the jaw had been attempted, at least in this
country, and both were considered as specimens
of fungus hematodes.

When the tumour re-appears after operation,
it does so in a very short space of time, often
before the wound has cicatrized and healed;

‘and as its situation is in the immediate neigh-

bourhood of the former disease, the fungus
protrudes through the wound, and seeis to
grow from it. In these cases the progress to a
fatal termination, which is inevitable, is per-
haps, fortunately for the patient, extremely
rapid also. Indeed in all cases of relapse, the
wth of the tumour goes on much more
quickly than in the original disease, and the
patient’s sufferings are considerably augmented
also. We have seen cases in which the pain
was so intense and so unremitting, that, night
or day, not a muiment’s rest could be obtained,
even under the influence of the largest doses of
Opium that could be adininistered with safety.

Cancer. Fungus hematodes.—We have al-
ready more than expressed a doubt that either
of these diseases ever originated in the usseous
structure, or could be considered as properly
appertaining to it, although it must Le conceded
that, in a few insulated cases, a cancerous dis-
peau has seemed to produce a fragility of

ones, and that this loss of the power of resist-
ance has preceded the developiment of the dis-
ease in the softer structures. But with the
utmost diligence of research we have not been
able to discover one case in which a morbid
alteration of structure, analogous to those chan-
ges in the soft parts which we call cancer, and
which contaminate the system through the 1ne-
dium of the soft parts, has been found within
the bone itself, or indeed to have existence
therein, independent of some similar degenera-
tion in the adjacent structures. On this sub-
ject, however, our knowledge must be extremely
imited. We do not well know what cancer is,
or what is meant by a cancerous diathesis. We
know not how to define or even to describe it
as a generic form of disease. The dissection
of these tumours exhibits an almost infinite
diversity of structure, and during life, previous
to the actual contamination of the system, when
the information too frequently avails but little,
it is difficult to say whether any given tumour
_—* this quality of malignancy or not.

e therefore do not offer a very positive or de-
cided opinion on this subject.

But that the bones in the vicinity of can-
cerous disease often suffer from a malignant
and incurable species of caries, quite distinct
and separate from that absorption which might
be the result of pressure, and that this caries

* Dub. Hosp. Reports, vol, iy.

463

illustrates Mr. Hunter’s position of the exist-
ence of a cancerous disposition in parts ap-
parently sound, which will afterwards become
developed even though the cancer is removed
by operation, admits, we think, of most irre-
fragable proof. Several years since, we re-
moved a very large cancerous ulceration in-
volving most of the under lip, the angle of the
mouth, and part of the upper lip also. The
diseased parts were most unsparingly taken
away, aud a minute and careful examination
could not detect the smallest hardness in any
part of the extensive resulting wound. Never-
theless, in less than a year afterwards a tumour
appeared at the angle of the jaw, with a hard
and unyielding band striking from it deeply
into the neck. The tumour increased and
pressed deeply: an operation was altogether
out of the question, and the man died of open
cancerous ulceration. On dissection the bone
was found to be deeply and extensively eaten
away by caries: its entire structure was pre-
ternaturally softened, and on attempting to dry
it, as an anatomical preparation, its earthy
material crumbled away and was altogether
lost. At this moment we have another case
affording a similar example of cancer attacking
the lower jaw after being apparently removed
from the lip. The bone is swollen, hard,
nodulated, and extremely painful; but not-
withstanding the urgent entreaties of the poor
man, no operation can be performed, and he
too will die of open cancer. But the point is
too well understood by operating surgeons to
require further elucidation. Every one must
have met with cases of extirpation of the
breast where the ribs had been found softened
and diseased, although little indication might |
have previously existed of such an unfortunate
complication.

But with reference to fungus hematodes
the question is by no means so easily settled.
In very many cases of extirpation of the eye
in consequence of this disease, the bones of
the orbit, even at a very early period, have
been found softened, altered, and spoiled, new
and imore irritable growths have sprung from
their substance, and the affection has re-appeared
in a worse, because a more incurable form.
Operations about the upper jaw have too fre-
quently proved failures from a similar cause.
Again, although the immediate points of re-
ference have escaped our recollection, we have
read of cases of fungus hemotodes, the very
first and earliest symptom of which was a
fracture of the bone or bones of the member
in which the disease afterwards was extensively
developed. In our own note-book are two
such cases. One, a poor boy admitted into
the Meath Hospital in the year 1820, with the
most frightful enlargement of the thigh per-
haps ever witnessed, the circumference of the
limb being much larger than that of the body
of an ordinary man. He attributed the dis-
ease to the almost spontaneous breaking of the
thigh-bone whilst he was riding on an ass.
The tumour never ulcerated, but as an ope-
ration, even at the hip-joint, was decided on in
consultation to be practicable, he left the

464

hospital, went to the country, and was lost
sight of. A case nearly similar occurred
shortly afterwards in the shoulder of a young
woman, the first symptom of which seemed to
have been a fracture of the humerus. Both
these cases were at the time regarded as spe-
cimens of fungus hematodes, and as they were
not examined, the question must still remain
undetermined ; but from what we have since
observed, we should be disposed to think they
were osteo-sarcoma. It is, perhaps, right to
State that many surgeons of high attainments
and great experience do not separate these
diseases in their own minds, and still regard
the affection of the bone, which we would en-
title osteo-sarcoma, as a species of fungus he-
matodes.

It is, however, only in the first and middle
stages that these morbid growths can be easily
confounded one with the other. Both appear
small at first, but increase with great rapidity ;
and both attain a size not often observed in
other tumours, the fatty tumour alone ex-
cepted. The same purple colour, the same
meandering of blue veins, and the same in-
equality of surface are found on both; and
when the osteo-sarcoma is about to ulcerate, it
may be observed to be soft in some places and
firm in others, like fungus hematodes. But
here the resemblance ends. Throughout the
entire case the osteo-sarcoma is harder, firmer,
and more unyielding: it attains to a much
greater size previous to ulceration, and when
ulcerated’ it does not shoot out (at least in its
more common forms) a soft and spongy and
bleeding fungus; neither does it destroy its
victim with such rapidity.

In the Repertoire Générale d’Anatomie et
de Physiologie Pathologiques (4 trimestre de
1826), there is an account of a disease of the
tibia related by Lallemand and commented on
by Breschet, who considered it to be some
species of aneurismal tumour, more particu-
larly as it is stated to have been cured by the
application of a ligature on the femoral artery.
The precise nature of this tumour, however,
is only conjectural, as it was never demonstrated
by dissection ; neither is it right in the present
state of our knowledge to question the cor-
rectness of these authors’ opinions. Nature
sometimes makes extraordinary deviations from
the ordinary courses both of disease and re-
covery, and the circumstance of our inability
to explain the processes adopted by her is not
sufficient to warrant a denial of their existence.
It may, however, be remarked that if the case
alluded to was, as is said, an aneurism situ-
ated within a bony case and cured by the
operation already stated, such recovery must
have been based on principles totally different
from those on which an artery is tied in an
ordinary case of aneurism.

In the museum of the school in Park-street,
there is a preparation perhaps in some de-
gree illustrative of this cellulated aneurismal
disease. It exhibits a morbid expansion of
the walls of a humerus removed from a woman
in Stevens’s Hospital: the entire shaft of the
bone seems to have been engaged, and the

BONE, PATHOLOGICAL CONDITIONS OF.

transverse diameter of the tumour is about
five inches and a half. Within area number ~
of cells lined by a vascular membrane of an
exceedingly dark red colour, the deep tinge
of which has scarcely been weakened by the
immersion of the preparation in fluid for more
than seven years ; and it is known that during
life this enormous tumour imparted an in-
distinct sense of pulsation. It appears by no
means improbable that the commencement of
this disease was in the medullary membrane,
which gradually became altered and poured
out the material, whether blood or otherwise,
with which its cells were filled. In proportion
as this accumulated, the cells must have en-
larged and the bone swelled. In many places
the external parietes are seen thinned down to
the strength of parchment or paper, and had
the disease been allowed to progress, they
might have been removed by absorption.
Had such an event occurred, and the integu-
ments subsequently given way, it is easy to
conceive that a fungus might have sprung from
this vascular membrane, which, occasionally
pouring forth an abundant and incontrollable
flow of blood, would in every particular have
so far resembled fungus hematodes, that even
an experienced practitioner might have found
it dificult to distinguish between them.

Te

BIBLIOGRAPHY.—Jsenflamm, Anmerk. tber d.
Knochen, 8vo. Erlang. 1782. Bonn, Thess. oss.
morbos. 4to. Amst. 1783; Hjus, Tab. oss. morbos.
fol. Amst. 1785-87. Heckeren, De osteogenesi
preternat. 4to. Lugd. Bat. 1797. Boyer, Lecons
sur les maladies des os, par Richerand, 2 vol. 8vo.
Paris, 1803; Anglice by Farrell. Sandifort, Museum
anatomicum. Weidmann, De necrosi ossium, fol.
Frfti. a M. 1793. Augustin, De spina ventosa
ossium, 4to. Hale, 1797. Howship on the morbid
structure of bones, &c., in Med. Chir. Trans.
vol. viii.; Ejus, Experiments, &c. on fractured
bones; Op. cit. vol. ix. and Sequel to the pre-
ceding paper in Op. cit. vol. x. * * Glisson, De
rachitide, 12mo. Lond. 1651. Stanley, Obs. on
bones in rickets, Op. cit. vol. vii. ** Scarpa, De
anat. et pathol. ossium, 4to. Ticin. 1827. B. Bell,
on the diseases of the bones, 8vo. Edinb. 1828.

* * Miiller, Diss. de callo ossium, 4to. Norimb.
1707. Bohmer, Diss. de ossium callo, 4to. Lips. 7
1748. Troja, De novorum ossium, &c. regenera-
tione, 8vo. Lutet. Paris. 1775. Russel, Essay
on necrosis, 8vo. Edinb. 1794. Koehler, Ex-
per. circa regenerationem ossium, 8vo. Gotting.
1786. Bonn u. Marrigues, Abhand. uber die Natur
und Erzeugung d. Callus, &c. 8vo. Leipz. 1786.
Lebel, Refiex. sur la regénération des os, in Journ.
Complem. vol. v. Breschet, Rech. sur la formation
du Cal. 4to. Paris, 1819 (parmi les Théses du
Concours). Meding, Diss. de regeneratione ossium,
4to. Lips. 1823. Kortum, Exper. et obs, circa re-
generat. ossium, 4to. Berol. 1824.**** Spondli,
Diss. de sensibilitate ossium morbosa, 4to. Gotting.
1814. Observations more or less connected with
the subject of the foregoing article will also be —
found in the surgical works of Bromfield, Gooch, —
Pott, &c., in Meckel’s Handbuch d. anatomie or —
Manuel d’anatomie, in Wilson’s Lectures on the
bones and joints, Lloyd on scrofula, Cooper & Travers’s
Surgical essays, Crowther on white swelling, Cope-—
land on the spine, Brodie on the joints, besides the
various articles already referred to in the Dicti
naire des Sciences Médicales, papers in the Dul
hee Reports, Dublin Journal, Medico-Chi
gical Transactions, &c.

; ie: a"

THE BRACHIAL OR HUMERAL ARTERY.

BRACHIAL OR HUMERAL ARTERY
(arteria brachialis, humeraria. Germ. die Ar-
marterie.) This artery is the continuation of
the trunk of the axillary. It commences at the
inferior margin of the tendons of the teres ma-
jor and latissimus dorsi, whence it extends to
about an inch below the bend of the elbow,
where it usually divides into the radial and
ulnar arteries; but not unfrequently this divi-
sion takes place high in the arm.

The brachial artery lies on the internal side
of the arm above, but in its course downwards
it gradually advances in an oblique direction
until it gets completely to the anterior surface
of the limb, where it is found situated nearly
midway between the condyles of the humerus
in front of the elbow joint; it is superficial in
the whole line of its course, in every part of
which its pulsations can easily be felt, and
sometimes, in the arms of thin persons, are
distinctly visible.

Relations.—Anteriorly the brachial artery
is overlapped, for about its upper fourth, by the
coraco-brachialis muscle and the median nerve;
for the greater part of its course down the arm
it is covered by the brachial aponeurosis, to
which is added, where it crosses the elbow, the
falciform expansion sent off from the tendon of
the biceps to the internal condyle: the median
basilic vein also lies in front of it opposite the
bend of the elbow. Posteriorly, for about a
third of its length from its commencement it
lies in front of the triceps, from which it is se-
parated by a quantity of loose cellular tissue
which envelopes the musculo-spiral nerve; in
its inferior two-thirds it rests on the brachizus
anticus. Internally it is covered by the bra-
chial aponeurosis at its superior part, where the
ulnar nerve is also in contact with it. The me-
dian nerve which crosses it, sometimes super-
ficially, and at other times passing more deeply,
in the middle of the arm gets to its internal
side, and continues to hold this relation to it in
the remainder of its course. Externally it lies
at first on the internal side of the humerus, from
which it is separated as it descends by the thin
muscular expansion in which the coraco-brachi-
alis terminates at the lower part of its insertion ;
in the remainder of its course the inner edge of
the biceps bounds it. The fleshy belly of this
muscle also partially covers it in front, a little
below the middle of the arm, At the bend of
the elbow, the relations of the brachial artery
become more numerous and complicated ; here
it inclines obliquely outwards and backwards,
and sinks into a space which is bounded on the
inner side by the origins of the pronator and
flexor muscles of the forearm, and on the out-
side by those of the supinators and extensors,
the floor of which space is formed by the bra-
chizus anticus muscle, from which the artery is
separated by a layer of adipose cellular mem-
brane. The artery is accompanied in its passage
into this space by the tendon of the biceps and
the median nerve, the former being situated to
its radial side, the latter to its ulnar; and it is
at the bottom of this space, opposite the coro-
noid process of the ulna, that the subdivision

of the artery into radial and ulnar usually takes
VOL. I.

465
place. As it enters the space the artery is
crossed by the semilunar fascia of the biceps, by
which it is separated from the internal cutaneous
nerve and median basilic vein. (For further par-
ticulars on this stage of the artery, see ELzow,
REGION OF THE.) ,

Two ven comites accompany the brachial
artery : they are included in its sheath, and lie
one on either side of it, often communicating
by several transverse branches which cross the
artery in front.

So superficial is the position of this artery
from its origin till it enters the region of the
bend of the elbow, that it may be exposed during
life in any part of its course with facility, and,
if the operator use only common caution, with
safety. In all this course the artery may be felt,
and in the upper third the operator may avail
himself of the inner side of the coraco-brachialis
muscle as a guide, and in the middle third, of
the inner edge of the belly of the biceps. In
both situations the operator has to avoid in-
juring the cutaneous nerves, and the median
and ulnar nerves, as well as the basilic vein,
which sometimes passes up as high as the
axilla. He should also bear in mind the po-
sition of the inferior profunda artery, which
is sometimes of a large size; and from its
direction, as well as its relation to the ulnar
nerve, presents a considerable resemblance to
the brachial trunk.

Branches.—-The brachial artery furnishes a
variable number of branches from its external
side, none of which is of sufficient importance
to be distinguished by a name; they are dis-
tributed to the os humeri, the deltoid, coraco-
brachialis, biceps, and brachizus anticus muscles,
and to the integuments. From its internal side,
however, there usually arise, in addition to
several small twigs sent to the triceps, teres
major, latissimus dorsi, and the integuments,
three branches of more considerable size, and
which derive their principal importance from
being the leading channels of anastomosis be-
tween the brachial trunk and the arteries of the
forearm. These are, 1, the superior profunda,
2, the inferior profunda, 3, the anastomotica
magna.*

1. The superior profunda (profunda humeri,
Haller and Semm. collaterale externe, Boyer,
grand musculaire du bras, Chauss.) arises from
the posterior side of the brachial artery, close to
the border of the axilla. It sometimes comes
from the axillary artery by a trunk common to
it and the posterior circumflex, and occasionally
it arises from the subscapular. Immediately
after its origin the profunda superior gives
several branches to the coraco-brachialis, triceps,
latissimus dorsi, teres major, and deltoid mus-
cles. Some of these latter, ascending towards
the acromion process of the scapula, anastomose
with the thoracica acromialis, supra-scapular and
posterior circumflex; while the branches sent
to the latissimus dorsi and teres major anas-
tomose with the subscapular artery. ‘The supe-

* Sometimes the subscapular, and one or both
of the circumflex arteries, derive their origin from
the brachial.

2H

466

rior profunda s backwards between the os
humeri and the long head of the triceps, and in
company with the musculo-spiral nerve enters
the spiral groove on the posterior surface of
the bone, passing between the second and third
heads of the triceps. About the middle of the
arm it divides into two branches, the internal or
ulnar, and the external or radial. The ulnar
branch descends in the substance of the triceps
to the olecranon process, around which it anas-
tomoses with the posterior ulnar and inter-
Osseous recurrent arteries, having in its course
supplied the triceps with several branches. The
radial branch comes forward with the musculo-
spiral nerve as far as the external intermuscular
ligament, where it separates from the nerve
and taking a more superficial course, descends
along the outer margin of the humerus over the
supinator radii longus and the triceps, to which
and the integuments it gives several branches.
On arriving at the external condyle it gives
branches to the elbow-joint, and anastomoses
with the radial recurrent in front, and the recur-
rent of the interosseous artery posteriorly.

Below the origin of the superior profunda a
small artery, called nutritia humeri, frequently
arises either from the superior profunda or the
brachial trunk : it enters the nutritious foramen
of the humerus, and is distributed to the can-
cellated structure of that bone.

2. The inferior profunda (ramus alius pos-
terior humeri, Haller) arises from the internal
side of the brachial artery, generally about the
lower part of the insertion of the coraco-brachialis
into the os humeri ; passing backwards, it per-
forates the internal intermuscular ligament, be-
hind which it descends, having the ulnar nerve
internal to it until it arrives at the posterior side
of the internal condyle, in the grooved depres-
sion between which and the olecranon it lies
close on the periosteum, and is covered by
the ulnar nerve: here it divides into several
branches, some of which are distributed to the
elbow joint and the muscles attached to the
internal condyle and olecranon, and it anasto-
moses freely with the posterior ulnar recurrent
artery. Sometimes the inferior profunda is a
branch of the superior artery of that name; it
varies very much as to its size in different
subjects, being sometimes a very insignificant
twig, while in other instances it is so large
that it is liable to be mistaken by an ope-
rator for the brachial trunk. In reference to
this latter circumstance Professor Harrison ob-
serves,* “In the dissected arm, the inferior
profunda artery appears at some distance from
the brachial, but if the triceps be pressed for-
ward towards the biceps, so as to place these
muscles as nearly as possible in their natural
relations, those vessels will be found very close
to each other; so that, in cutting down upon
the brachial artery in the middle of the arm, in
the living subject, the inferior profunda, from
its situation, and from its being accompanied
by the ulnar nerve, may be mistaken for the
brachial. This error, however, may be avoided
by recollecting that the brachial artery is the

+ Surgical Anat. of the Arteries, vol. i. p. 176.

THE BRACHIAL OR HUMERAL ARTERY.

nearest to the triceps, and is a little covered by
that muscle: in general, also, there is a material
difference in size between the two vessels.”

The remarks contained in the foregoing quo-
tation do not apply to a merely hypothetical
case, but to one which has actually occurred in

ractice, the following instance of which I once

ad an opportunity of witnessing. A late emi-
nent surgeon undertook to tie the brachial artery
for the cure of an aneurism at the bend of the
elbow: the inferior profunda, which was un-
usually large, was exposed and tied on the
supposition of its being the brachial artery,
the pulsation in the tumour continuing un-
diminished pointed out the nature of the mis-
take which had been committed, and the patient
had to submit to a second operation at a sub-
sequent period, in which the brachial artery was
tied with a successful result as to the cure of the
aneurism.*

3. The anastomotica magna, (ramus anasto-
moticus, Haller, collaterale du coude, Ch.) arises
generally at nearly a right angle from the inner
side of the brachial, at a little distance above
the elbow-joint. Several similar vessels, but of
much smaller size, arise from the same source in
its vicinity: at first it passes inwards across the
brachizeus anticus, and perforates the internal
intermuscular ligament, giving branches to the
brachizus anticus, the triceps, the cellular tissue
and lymphatics above the internal condyle:
having got upon the triceps, it descends to the
back part of the internal condyle, where it
anastomoses with the inferior profunda and
posterior ulnar recutrent arteries. When the
inferior profunda happens to be very small, or
is absent, this vessel supplies its place by giving
branches to the articulation, to the muscles at-
tached to the internal condyle, and for- anasto-
mosis with the posterior ulnar recurrent. Where
the anastomotica magna is absent, small branches
from the brachial, inferior profunda, and ulnar
recurrent arteries, supply its place. When a
high division of the brachial artery occurs, the
branch which is to become the ulnar usually
gives off the two profunde, and the anasto-
motica magna: this last, however, sometimes
comes from the radial in such cases.+

* [Such a mistake as that alluded to in the text
may likewise occur where there has been a high
bifurcation of the brachial artery.—ED.

+ [The frequent occurrence of irregularity as to the
position at which the brachial trunk divides into its
terminal branches, the radial and ulnar, constitutes

a point of great interest in the anatomical history

of this artery. I believe it may be said that it never
happens that the bifurcation takes place below the
coronoid process of the ulna; on the contrary, the

division above that point is by no means uncommon, ~

occurring, according to the calculation of Professor
Harrison, once in'every four subjects. This bifur-
cation occurs at all points in the arm, and in some
cases the radial and ulnar arteries proceed at once
from the axillary. In general the anomalous artery
is the radial, and is subcutaneous in its course,
while the ulnar follows the normal course of the

brachial trunk. Sometimes the reverse is the case:
sometimes both radial and ulnar are subcutaneous,
and sometimes the radial is at its origin ulnad, ©

but afterwards crosses the ulnar artery at a very
acute angle, to get to the radial side.
cases the brachial artery is regular in its course,

In some rare _

q

) ne — es

BURSZ MUCOSE: 467

Anastomoses —The ascending branches of
the superior profunda anastomose in the sub-
stance of the deltoid muscle with the anterior
and posterior circumflex and the cephalic branch
of the acromial thoracic, and with the subsca-

ular and the axillary branches of the thoracica
ongior in the axilla. If the brachial artery be
obliterated by disease or the application of a
ligature above the origin of the superior pro-
funda, the blood will be carried by the circuitous
route of these anastomoses into the brachial
artery and all its branches from the superior
profunda downwards.

When the brachial artery is obliterated near
the elbow, the circulation is maintained in the
forearm and hand by the anastomoses of both
profunde and the anastomotica magna with the
recurrent branches of the radial, ulnar, and in-
terosseous arteries. The anastomosis kept up
between all the branches of the brachial artery
along the periosteum of the humerus, in the
substance of the muscles and in the integu-
ments of the arm, is so free as to be sufficient
to ensure the circulation in the limb even if the
brachial artery were obliterated throughout the
whole of its length.

For the BIBLIOGRAPHY, see that of ANATOMY
(INTRODUCTION) and of ARTERY.

(J. Hart.)

BRAIN. See Eyvxeruaton, and Nervous
System (Comp. Anat.)

BURSZ MUCOSE. (Fr. bourses synovi-
ales; Germ. die Shleimbeutel.)—This name was
first given by Albinus to small shut sacs, filled
with an unctuous fluid, which he found in
certain parts of the body, interposed between
the tendons and bones. The name, however,
is now much more extensively applied, for ana-
tomists have ascertained that those smooth
membranes, previously noticed by Winslow,
covering the tendons and lining the tendinous
sheaths about the wrists and ankles, are strictly
of the same nature as those described by the
Dutch anatomist. The number of burse known
to Albinus, and described by him in his “ His-
toria Musculorum,” was but sixteen pairs.
Monro, who first properly explained their ana-
tomy and uses in his excellent monograph upon
this subject, has made us acquainted with no
less than seventy pairs, all situated in the ex-
tremities: and since his day the number has
been further increased by the discoveries of
Beclard and others: so that anatomists are now
acquainted with upwards of one hundred pairs,
many of them situated in the head and trunk.

Burse mucosz, though of the same structure
and answering the same ends in every situation

but — off the interosseous high up, which has
all the appearance and many of the dangers of the
high bifurcation. Mr. Harrison mentions a case
in which the brachial divided into three branches,
two of which united to form the radial, which gave
off the anterior interosseous, the posterior being
derived from the third, the ulnar. Mr. Burns re-
marks, that when, as rarely happens, the ulnar
is the anomalous branch, the bi:urcation eneraily
takes place nearer the axilla, than when the radial
is the abnormal vessel.—ED.]

where they occur, may nevertheless be divided,
with advantage, into two great classes; viz.,
I. the subcutaneous burse, or those placed be-
tween the skin and fascia; and, II. the deep
burse, or those which lie beneath the latter
membrane.

I. The subcutaneous or superficial burse
were unknown not only to Albinus, but even to
Monro and Bichat; at least there is no mention
made of them in the works of any of these
authors. Beclard, in his “ Additions to the
General Anatomy of Bichat,” appears to be
the first anatomist who refers distinctly to
them. The most remarkable are,—1, a large
one placed between the skin and the liga-
mentum patelle ; 2, one between the skin and
fascia covering the great trochanter of the femur ;
3, one between the skin and fascia over the
olecranon. These are all extremely well marked.
There are others likewise, which, though less
perfectly developed, are, however, evidently
of the same nature; such as that between
the skin and fascia over the angle of the
lower jaw, and those found upon the dorsum of
the hand beneath the phalangeal and meta-
carpo-phalangeal articulations. These super-
ficial burse are not equally perfect in all im-
dividuals: they are best developed in those
whose limbs are actively and habitually exer-
cised. On cutting into their cavities we gene-
rally find them traversed by numerous fila-
ments: the appearance indeed is extremely
similar to that presented by the subcutaneous
cellular tissue in certain parts of the body,—in
the palpebra and penis, for example ; and this
no doubt is the reason why these burse were
not distinguished from cellular membrane by
Monro and others. That they are different
structures, however, or at least that they are
independent of the cellular system, is sufficiently
proved by the simple process of inflating their
cavities through asmall opening made into them ;
we then find that the air is circumscribed within
a definite boundary, and cannot, as in the
palpebra and penis, be made to pass into the
surrounding cellular membrane.

II. The deep bursa, or those placed beneath
the fascia, are much more numerous and much
better marked than the preceding. They are
almost uniformly found in connexion with ten-
dons, and, generally speaking, are interposed
between them and the bones over which they
play. Like the superficial ones, they too are
always shut sacs, in most instances of an ex-
tremely simple form, but in some cases much
more complex; and hence they may with pro-
priety be subdivided into two sets,—the vesi-
cular and the vaginal.

a. The deep vesicular burse, when fully dis-
tended, represent each a simple globular bag, one
of whose sides is in contact with the bone, and
the other with one side of the tendon, without,
however, enveloping it. (See fig. 111, 6.) On
opening into its cavity, it is found to con-
tain a viscid fluid, more or less abundant,
and this is sometimes traversed by fila-
ments passing from one wall of the sac
to the other. They generally occur in the
neighbourhood of the great articulations of

2H 2

:

468

the hip, shoulder, knee, and ankle, but are
not, as it was supposed until of late years, con-
fined to the extremities, for we shall presently
point out instances of their occurrence both in
the head and trunk. Amongst the most re-
markable in the inferior extremity we find, in
the neighbourhood of the hip-joint, a very large
one between the tendon of the psoas muscle
and the capsular ligament; a large one between
the great trochanter and gluteus maximus;
one between the gluteus maximus and vastus
externus; one between the gluteus medius and
trochanter; one between the gluteus minimus
and trochanter; one between the pectineus and
femur. These are all large and regular in their
existence ; but there are other smaller ones fre-
quently met with, particularly at the posterior
part of the joint connected with the small ten-
dons and muscles placed there. About the
knee-joint there are likewise several vesicular
burse : immediately above the articulation, be-
tween the extensors and front of the femur,
there is an extremely large one, oftentimes ex-
tending several inches upwards, and still more
remarkable in many instances for communi-
cating with the synovial membrane of the joint;
a fact which has been well appealed to by the
general anatomist in proof of the anatomical
identity of these two structures. There is a
large one, likewise, at the inner and lower part
of the articulation between the tibia and the
tendons of the sartorius, gracilis and semi-
tendinosus: posteriorly between the origins of
the gastrocnemii and the bone there is also
found a bursa; and a similar one between the
poplitens muscle and the joint. These, like
the large one in front, generally communicate
freely with the articular synovial membrane.
There is also a bursa generally found between
the semi-membranosus and the internal lateral
ligament. Around the ankle there are but few
vesicular burs: posteriorly, however, between
the tendo Achillis and os calcis, there is found a
very large one; and smaller ones are frequently
met with connected with the flexor pollicis
longus, and some of the other muscles in their
passage here. ‘ In the superior extremity we find,
likewise, several vesicular burse: around the
shoulder-joint there is a very large and regular
one placed between the deltoid muscle and the
capsular ligament; there is one between the
clavicle and coracoid process; one between
the scapula and subscapular muscle; one be-
tween the subscapular muscle and the capsule.
Lower down there is a bursa between the
humerus and the tendons of the teres major
and latissimus dorsi; and also a bursa fre-
quently between these two tendons, at a little
distance from their insertion. About the elbow-
joint there is a vesicular bursa between the
tendon of the triceps and the olecranon;
one in front, between the tendon of the biceps
and the tubercle of the radius: there is also
one between the head of the radius behind, and
the extensor muscles passing over it. Around
the wrist-joint there are no vesicular burse of
any size or importance. There is in the trunk
a large vesicular bursa, usually found between
the latissimus dorsi and scapula. In the head

BURSE MUCOSE.

are transmitted.

we often see a distinct bursa interposed between
the two divisions of the masseter muscle. —~

b. The deep vaginal burse are invariably
found connected with tendons and with the
fibrous sheaths through which these tendons
They are somewhat more
complex than the preceding, for instead of
representing a simple shut sac, they form, like.
serous membranes, by reflexion a double sac,
one of whose portions, corresponding, for ex-
ample, to the plura costalis, lines the interior
of the fibrous sheath, while the other, answering
to the plura pulmonalis, invests the surface of
the tendon. There is, however, this difference
between the pleure and the synovial sac, that in
the latter there is no longitudinal septum, no
mediastinum resulting from the reflexion of the
membrane ; for the reflexion occurs not along
the channel, but at either extremity of the
fibrous sheath: thus the bursa, if completely
detached from all surrounding structures, would
represent a large tube, containing within itself
a smaller one; these two being continuous by
their extremities alone.

The deep vaginal burse generally occur in
the neighbourhood of ginglymoid articulations,
and by far the largest and most interesting are
those connected with the flexor tendons of the
wrist and ankle. They are always of very great
size, not only passing a considerable way up-
wards upon the forearm and leg, but likewise
extending downwards into the palm of the hand
and sole of the foot, and branching out at their
distant extremity into several distinct sheaths
for the respective tendons belonging to the
different toes and fingers. Upon the phalanges
the synovial sheath is firmly bound down by
a dense unyielding fibrous membrane, a cir-
cumstance well worthy of remark; for, as we
shall presently see, it modifies in a very im-
portant degree the characters of inflammation
occurring here. Besides these, we have a re-
markable vaginal bursa connected with the long
head of the biceps muscle; and smaller ones
are found investing the tendons of the cireum-
flexus palati, obturator internus, &c.

Having thus considered the forms and rela-
tions of the different sorts of burse, we may
next proceed to offer a few remarks applicable
alike to all, upon their structure, contents, uses,
development, and diseases. Here, however, our
labour is much abridged by the fact already
alluded to, and now admitted upon all hands,
that the membrane forming the burse, and the
synovial membrane of joints, are anatomically
and physiologically the same. They are, in
fact, the same in form, being both shut sacs ;
the same in structure, being both essentially
composed of cellular membrane; the same in
function, for they are both designed to facilitate
the motion of contiguous organs; and, as we
shall presently see, they are both similarly af-
fected by disease. Were we to enter at length
into these particulars upon the present occasion, —
we should but anticipate details belonging pro-
perly to a more general head, that, namely, of
synovial membrane. ence the few remarks we _
are now about to offer must be receivedas merely _
supplementary to those found under that article.

ve ee ee eee

BURSZ MUCOS2Z.

1. Structure——The opinion of Haller, that
these membranes are ultimately composed of
cellular substance, though controverted by
Monro and others, is, however, now universally
admitted. They are, in fact, like all synovial
membranes, essentially composed of cellular
substance, entirely destitute of fibre, scantily
supplied with vessels, and remarkable for their
sohnens and flexibility. The vaginal burse
are, however, much more delicate than the
vesicular. The, fatty bundles, mistaken by
Havers for glands, are frequently found in their
substance. Rosenmiiller speaks of distinct
synovial follicles as likewise demonstrable, but

e existence of any such bodies appears to us
more than doubtful.

_ 2. Contents.—Experiments have been made
by Monro and others, to shew that the fluid
contained in bursz is similar to that contained

‘in synovial membranes. These, however, may

now be looked upon as superfluous, inasmuch as
this question has merged in the general one, viz ,
the identity of the two structures. Chemistry,
in fact, has proved that their fluid and that of
synovia] membranes are, if not completely, at
least essentially the same. In the subcutaneous
burse it is scanty and thin; in the larger and
deeper ones it is said to be somewhat more

’ viscid.

8. Function.—The use of burse is in all
cases the same; they ferve to isolate certain
parts and facilitate the motions performed by
them: hence they are found only in those
situations which are the seat of motion. Their
fluid, from its oily consistence, must of course
tend considerably to diminish the effects of fric-
tion.

4. Development.—Burse are developed at a
very early period, and are relatively more
pliant and perfect in the child than in the
adult, to facilitate, as it would appear, the

almost incessant movements natural to that

period of life. They become more dense and
unyielding in the adult, and in extreme old age

are said to become dry and rigid. This, no

doubt, is amongst the causes which render the

' movements of old age slow and laboured. A

curious fact connected with this subject is the
accidental development of burse in cases where
their Ag becomes necessary. When the
superficial bursa in front of the patella has
been removed by operation, its place is ulti-
mately supplied, as Sir Benjamin Brodie has
seen, by a newly formed one, similar in every
respect to the original sac. In cases of club-
foot a large subcutaneous bursa has been found
So upon that portion of the swelling
which has been the chief seat of pressure and
motion: and in cases of diseased spine, at-
tended with considerable angular curvature, a
bursa has become developed between the pro-
jecting spinous process and the skin.
ATHOLOGICAL CONDITIONS OF BURSE MU-
cosa.—Burse mucose, superficial as well as
deep, are not unfrequently the seat of inflamma-
tion, resulting either from external causes, such
as cold or local injury, or from constitutional
causes. In the majority of cases inflammation in
these structures assumes a chronic form, and its

469

ordinary effects are either to inerease the quan-
tity of the synovial fluid, to determine the
effusion of a turbid serum loaded with flakes of
lymph, or to end in the formation of matter.

The general phenomena of bursal inflamma-
tion may be studied with most advantage in the
large subcutaneous bursa in front of the knee-
joint: it is more frequently inflamed than any
other in the system. This, however, is not
owing to any peculiarity of structure predis-
posing it to disease, but merely to the accidental
circumstance of its situation, which exposes
it more than any other to external injury. In
those persons who continue for a long time
in the kneeling attitude, in devotional exer-
cises for example, and still more remarkably
in those whose occupation obliges them not
only to support the body but also to move
upon the knees (as carpenters, housemaids,
and others), inflammation of this bursa is very
frequently met with. In many instances it
occasions little general or local disturbance,
merely causing an increased effusion of the
proper synovial secretion, without producing
any change whatever in its natural properties.
In other cases the fluid is not only increased
in quantity, but becomes changed likewise in
quality ; it assumes the appearance of a turbid
serum, with numerous flakes of lymph floating
in it; or where the disease has been of long
standing, the fluid is frequently found loaded
with a number of loose bodies, almost of the
consistence of cartilage, and of a flattened oval
form. Sir Benjamin Brodie compares their
appearance not inaptly to that of melon-seeds,
and he considers them as portions of lymph
originally of an irregular shape, but which, by
the motions and pressure of the surrounding
parts, have had their angles worn off, and
assumed by degrees a firm consistence. They
have been found likewise in the smaller burse.
Monro has seen upwards of fifty extracted from
the small bursa of the flexor pollicis longus
tendon, where, by excessively distending the
surrounding parts, they had produced severe
pain. When the great vaginal burse of the
flexor tendons have become the seat of effusion,
a very remarkable appearance may present itself,
at once explicable, however, by referring to the
anatomy of the part. The fluid can by pressure
be forced downwards under the annular liga-
ment, and into the palm of the hand, and thence
upwards again into the forearm. Some authors
have deemed it proper to designate by a par-
ticular name this termination of the disease by
effusion, and the words ¢hygroma and ganglion
have been applied with a good deal of con-
fusion by different persons; but it appears to
us that there exists no necessity for a specific
name to refer to this accidental mode in which
inflammation terminates.

A much more important termination of the
disease is that in which, owing to local or con-
stitutional causes above alluded to, the inflam-
mation, having run a severer course, ends in
suppuration. Sir Benjamin Brodie has in this
case observed that the matter may take either
of two courses: it may come directly to the
surface ; or, without pointing forwards, it may

470
penetrate the side of the sac, and so become
extensively diffused through the surrounding
cellular membrane, involving the whole anterior
and lateral portions of the joint. In sucha
case the practitioner is very liable to be de-
ceived as to the true character of the abscess,
and to confound it with those which originate
in the cellular membrane.

There are certain cases in which acute inflam-
mation of a bursa becomes even a more serious
disease than that just alluded to. In the syno-
vial sheaths of the flexor tendons, for example,
the progress and termination of the inflamma~-
tion are often modified in a remarkable manner
by the anatomical peculiarities of that part. In
that form of the paronychia affecting the ante-
rior part of the finger, and seated in the synovial
sheath of its flexor tendon, the inflamed mem-
brane is closely bound down by a dense and
unyielding fibrous layer: hence not only death
of the contained tendon may be produced, but
even extension of the disease to the bone itself.

Such are the morbid changes usually met
with in the contents of inflamed burse; but if
the disease have been of long standing, changes
scarcely less remarkable are produced in the
structure of the bursa itself. Instead of the
delicate synovial membrane we have above
described, it is frequently found converted into
a firm gristly substance, sometimes half an
inch in thickness. In such cases no tact, how-
ever delicate and experienced, could, previously
to operation, have detected the presence of
matter.

Monro seems to regard, in certain cases at
least, the communication above alluded to be-
tween certain burse and the neighbouring joints
as the result of rupture or of friction: he even
considers it remarkable that in such instances
neither lameness nor pain had been complained
of during the lifetime of the individual. It ap-
pears to us, however, much more probable that
in those instances the synovial membrane of the
joint and that of the bursa have been ab initio
but different parts of one and the same structure ;
at least, in our dissections of the subcrureus
bursa in young subjects, we have more than
once observed it communicating freely with
the joint.

For Bibliography, see that of SYNOVIAL Mem-

BRANE.
(John E. Brenan.)

CARNIVORA (caro, carnis, and voro, ) an
interesting and highly important group of the
mammifera, constituting the typical order of
that great division of the class which feed
upon animal aliment. Whether the present
group can with propriety be considered as en-
titled by its organization to the ordinal rank
which we have assigned to it above, or whether
it does not rather form a subdivision of a great
order, answering nearly to the Carnassiers of
Cuvier, is a question which, as it is variously
viewed by different naturalists, may be safely
left undecided in a work like the present, in
which structure rather than arrangement is the
principal object of research, and in which the
nomenclature of a system is of little importance,

CARNIVORA.

compared with the devel nt of anatomical
and physiological truth. The Carnassiers of
Cuvier (excluding the Marsupiata, which may —
unhesitatingly be considered as a_ distinct
order,) includes a natural and tolerably well
defined assemblage of animals, to which the
term ZoopuaGa may with propriety be applied
as the classical equivalent to the French phrase
of that distinguished zoologist; but however
the stricter rules of zoological arrangement may
render it difficult to divide this group into the
three orders of Currroprera, INSECTIVORA,
and Carnivora, it has appeared to the
author of this essay as more convenient on
the present occasion to assign that designation
to each of these divisions, and to make the
structure of each the subject of a separate
article.

The characters of the Carnivora as distinct
from the rest of the digitate animals possessing
the three distinct classes of teeth, (which, be-
sides the other Zoophaga, include the Quadru-
mana and the Marsupiata,) are such as point
them out as especially formed for the pursuit
and destruction of vertebrate animals. They
possess in the upper and in the lower jaw six
incisive teeth, a large, strong, and pointed ca-
nine tooth on each side, and molar teeth which
partake in a greater or less degree of the charac-
ters distinctive of the class, according to the
habits of the different genera. These molars con-
sist of three distinct kinds: the anterior, which
immediately follow the canine, are more or less
pointed, and are termed false molars; the next
class, formed especially for cutting in pieces
the flesh on which the animals feed, are termed
by M. Frederick Cuvier Carnassiers; and the
posterior are tuberculated. The proportion
which these different classes of teeth bear to
each other in number or developement, accords
with the degree of the carnivorous propensity
in the animal.

In agreement with these characters of the
teeth, the feet are digitate, the toes furnished
with claws, which in some are retractile; the
stomach is simple, the intestines are short, and
the ccecum is either very small or altogether
wanting.

The animals of this order differ in the form.
and position of the posterior feet; in some,
hence termed plantigrade, the whole foot rests
on the ground; in others, called digitigrade,
the toes only touch the ground, the heel being
considerably raised. Of the former structure
the bears exhibit the type, and the cats of the
latter. A third and most remarkable form of
the extremities is shown in the Seal tribe, in
which the anterior as well as the posterior feet
are formed for swimming, being spread into fin-
like paddles.

The families of which this order is com-
posed are perhaps as follow :— s
1. Ursipa, typical genus Ursus, bear.

2. Musretipz, do. Mustela, marten.
3. Canipa, do. Canis, dog, wolf.
4. Frevipa, do. Felis, cat.

5. Puocipz, do. Phoca, seal.

Of these families the FeLrp& constitute the —
type of the order, possessing the carnivorous

CARNIVORA.

propensity and structure in a higher degree
than any of the others.

Skeleton.—The structure of the skeleton in
the cat tribe exhibits, in the greatest imaginable
degree, all the requisites of fleetness, activity,
and power, for the purpose of pursuing, sur-
prising, overpowering, and tearing the living

Fig.

configuration of the bones, in their articulation,
and in the developement of the different points
of muscular attachment, such a combination of
lightness of form with vast power, as must
strike every one as being exactly equivalent to
the natural requirements of the animal. The
Spine is flexile, yet of great strength, and the
extent and robustness of the lumbar portion of
the vertebral column seem at once adapted for the
exercise of that flexibility, and for the location
of powerful muscles. The ribs are narrow
and far asunder ; the limbs long, powerful, and
so constructed as to afford the greatest facility
and extent of motion, an object which is
greatly promoted by placing the point of rest

471

prey on which, in a state of nature, they
wholly subsist. In the less typical forms we
find these attributes possessed to a modified
extent, but still admirably adapted to their
respective habits.

s an example of the typical structure, the
skeleton of the lion (fig. 189) shews, in the

189.

at the extremity of the toes; the whole of the
feet, excepting that part, being thus made sub-

servient to the object in question. The cra-
nium is broad and short, and fitted for the
exercise of almost incalculable force in holding
and tearing their food.

In the weasel tribe the legs are shorter, the
vertebral column elongated and in the highest
degree slender and flexible, the lumbar region
being as long even as the dorsal, a structure
by which they are enabled to creep with almost
a serpentine motion in quest of the small and
sometimes subterraneous animals on which
they subsist.

In the bear tribe (fig. 190) there is a still

= Ss
~~ *.
—J Ke, “.
ee y Fi :
>
* ee

way
Wil yy.
“Whe A fo tha, pore"

472
greater aberration from the type, in the planti-
grade form of the foot, by which the animal is
enabled to walk with that solidity and firmness
which the less degree of mobility in the rest

of the skeleton renders necessary, or to climb
trees, or dig the ground, in pursuit of the

yi

ifs

MAREE

\

we?

other hand, the most
remarkable deviation x
from the typical struc- YN
ture is seen in the adaptation of
the limbs to the aquatic residence
and habits of the animals. The
posterior members are extended
backwards in a horizontal direc-
tion, forming two broad fins, by
which they swim with great facility
and strength. The anterior feet are
similarly constructed, but they serve
also in some measure for progres-
sion on land, though to a limited
extent. The cranium is thin and
round, and the teeth, sharp and
many-pointed, are formed for seiz-
ing, holding, and tearing fish, the activity of
whose motions, no less than their scaly surface
and even, rounded form, render such a structure
absolutely necessary.

_The cranium.—The peculiarities by which
the cranium of this order is distinguished have
reference, not to the form and developement of
the brain only, but particularly to the character
of the food, and the consequent necessity of
peculiar powers of mastication, and of the
other acts preparatory to the function of diges-
tion. We shall find, therefore, not only that
the general form of the skull in the whole of
the Carnivora is diffe-
rent from those of every
other group, but that the
families composing it
differ in minor points of
structure, with the same
relation to aliment and
habits. The cranium in
this order then is cha-
racterized, when com-
pared with that of most
other orders, especially
those which feed on
grain or other substances
requiring long and la-
borious trituration, by
great shortening of the

CARNIVORA.

various food from which the different genera of
this family derive their nutriment. The small
extent of the lumbar portion of the spine com~-
pared with the dorsal which we find in some
of this tribe, is equally characteristic. |

In the Phocidz or Seals, (fig. 191), on the

Peay

— =
PAPAS enemenate mem aeeenemermrner, oe

297223 GSE

bs

*

bones of the face. This is particularly con-
spicuous in the cats, (fig. 192,) the seals,

Fig. 1992.

—————E——————— CC or, Cl

- dual bones com

CARNIVORA. 473

peeetice aspect is generally small, directed
ackwards, and separated by a strong occipital
crest from the anterior parts of the skull. From
this, in many instances, a strong, elevated, me-
dian crest passes forwards, which is remarkably
short in the lion, the white bear, the hyena,
the badger, and many others. It is remarkable
that in many of the Phocidz this crest does not
exist, whilst in other species it attains a con-
siderable size. The orbit and the immense
temporal fossa are confounded in one great
excavation; the zygomatic arch is perfect and
of considerable size. The anterior opening of
the nares is large, and directed forwards, ex-
cepting in certain seals, in which it is placed

‘almost vertically, for the obvious purpose of

facilitating its exposure to the atmosphere when
these animals come to the surface to breathe.

A remarkable peculiarity exists in this order,
in the existence of a bony process arising from
the internal surface of the occipital and parietal
bones, and separating the lobes of the cerebrum
from the cerebellum. This process, of mode-
rate size in the dogs, is much larger in the seals,
and still more developed in the cats. In the
dogs it is considerable from before backwards,
but small from side to side; it is formed by
the parietal and the squamous portion of the
occipital. In the seals the parietal bone is not
concerned in its formation ; in the cats, on the
contrary, it entirely arises from this bone, not
being at all connected with the occipital. The
object of this bony tentorium is obviously to
support the different portions of the brain, and
prevent their pressing upon each other during
the sudden and violent movements of the ani-
mal, when springing upon its prey or leaping
with great violence.

With regard to the substance of the bones of
the cranium in this order, although it may be
observed generally that they are of a medium
degree of thickness and solidity, there are re-
markable exceptions in some of the seals, in
which tliey exhibit an extreme degree of tenuity,
the object of which, in reference to the medium
in which the seals reside, and the necessity of
often rising to the surface to breathe, is suffici-
ently obvious. fn the cats and other genera,
where extraordinary and sudden exertion is
frequently necessary, the bones altogether are

- found to be remarkably compact and solid.

A few details of the structure of the indivi-
sing the cranium will be
necessary, in order to shew how admirably
every portion is made to bear upon the general
objects of the whole organization.

The frontal bones, (fig. 192, 193, 194, e,)
which, as in most other instances, are separate,
have a considerable developement of the zygo-
matic or external angular process, especially in
those whose habits are preeminently carnivorous,
as in the cats, the mustelide, &c. Inthe ichneu-
mons it even extends so far as to meet the orbi-
tary process of the malar bone, and thus form
a complete orbitar circle ; the cats exhibit an
approach to such a formation, but in the other
tribes it is less and less marked, and in the seals

there is scarcely the vestige of this process to
be perceived.

The parietal bones (_f_) are of a quadrate form ;
they are early united in the mustele, the cats, the
hyenas, and the bears; in the dogs and in the
seals, &c. they remain more durably separated.
The interparietal bone, as it is called, (a large
os triquetrum,) which is found in many ani-
mals, particularly during the young state, is
considerable in the dogs, in which it remains
permanently distinct from the parietal and oc-
cipital. Its form in these is that of an elon-
gated triangle, which extends forwards, sepa-
rating the two parietal bones for more than half
their length. In this instance it proceeds from
a single point of ossification, whilst in many
of the rodentia it arises from two centres of
developement. The crest which is formed
along the median line of the cranium, at the
junction of the parietal bones, and which forms
a continuation forwards from the ridge of the
occipital, is greatly developed in the older cats
and others. The lion and tiger, the wolf and
the bear, the badger and many others, exhibit
it in an extraordinary degree. Its object is
evidently to afford a strong and extended sur- '
face of attachment to the powerful temporal
muscles, which are required to be enormously
developed for the purpose of cutting and tearing
in pieces the hard tendinous portions of the
animal’s prey.

The temporal bone (g_) is divided, as in the
other mammalia, into a cranial or squamous,
and a petrous or acoustic bone. The former
constitutes the posterior and superior portion
of the zygomatic arch, and beneath the root of
this process is situated the articular cavity for
the reception of the condyle of the lower jaw.
Its transverse form, and the depth of its ante-
rior and posterior boundaries, afford a stron
and secure hold of the condyle, which, whilst
it thus moves freely within its limited sphere
of action, is restricted from any other than
a simple hinge-like motion. This circum-
stance adds greatly to the power of this parti-
cular kind of mastication. The squamous
portion is but small, and is externally more or
less convex. The acoustic portion is greatly
developed in the cats, and still more so in the
seals, a circumstance which will be further
alluded to hereafter.

The occipital bone varies much in the car-
nivora. In the seals the superior or squamous
portion is large, obtusely triangular, and much
flattened, being in many species devoid of the
strong occipital ridge which is so prominent a
feature in all the other families of the order.
In the cats this process is very prominent and
strong, forming a solid attachment for those
powerful muscles which are necessary for the
forcible and even violent raising of the head in
tearing the prey to pieces. It is also strongly
marked in most of the Urside, particularly in
the white bear, the badger, the coati, &c.
The inferior portion, answering to the cuneiform
process, is in the seals remarkably broad and

thin, much more so than in any other of the

mammifera; and in this part there is in some
species of that family an oval hole of consi-
derable size, placed near the inferior margin of
the foramen magnum. This exists only in cer-

474

tain species, in Ph. vitulina for instance, and ap-
pears to harmonize with the tendency to scanty
deposition of bony matter, which characterizes
the whole cranium in this family. The con-
dyles in these animals are also very much
larger than in the other carnivora.

Lhe sphenoid bone has nothing very remark-
able in its structure, excepting the greater
developement of its ale in these than in most
others of the mammalia, and the small com-
pressed triangular form of the pterygoid pro-
cesses which in the cats are long and hooked
backwards.

The superior maxillary bone consists of the
true or posterior maxillary (c_) and the intermax-
illary (a) portions. For the sake of clearness
they may be described as distinct bones. The
body of the maxillary bone extends very high up
in the cats, andis remarkably strong and compact.
In the seals it is encroached upon by the nasal
Opening, so as to leave only a narrow neck be-
tween that opening and the orbit. The infra-
orbitar foramen is remarkably large in the cats
and in the seals, in which animals the long elastic
setaceous whiskers are so useful as feelers, and
are supplied with large filaments of the infra-or-
bitary branch of the fifth pair of nerves. The
length of the body of this bone depends on
the number and nature of the teeth which are
imbedded in it, and is shorter in proportion to
the predominance of the strictly carnivorous
appetite. The canine teeth and the molares
are those which occupy this bone, the incisores
being placed in the intermaxillary; and in the
cats the body of the bone is remarkably short,
being occupied only by four molar teeth, the
first of which is small and rudimentary, as
well as the posterior one, which is small and
tubercular ; the two middle ones are formed for
cutting asunder the flesh, and are exceedingly
strong. Inthe bears the teeth assume more of a
tubercular form, and are, in fact, adapted for mas-
ticating vegetable substances as well as animal
matters; the jaw-bone is, therefore, much longer
than in the cats. In the dogs, which hold an
intermediate place in this respect, the molar
teeth are six in number, and the two posterior
ones are more or less tubercular. The anterior
part of the jaw is enlarged and rounded for
the location of the large and powerful canine
teeth. Inthe Walrus (fig. 195,) the anterior
part of this bone is greatly enlarged for the
enormous canine teeth, which form powerful
weapons, with which the animal strikes directly
down with immense force.

The intermaxillary bones contain each three
small incisor teeth: these in the cats are
very small, excepting the external one, which
is somewhat larger than the others. In the
seals they are pointed. These bones are con-
siderably smaller in the carnivora than in most
other orders.

The nasal bones (b) are smaller in this order
than in many others. In the cats they are
rather broad anteriorly, but short; they are
longer in the dogs and bears, agreeably to the
greater length of the face generally. In the
seals they are much shortened, in order to allow
of the great expansion, in an upward direction,

CARNIVORA.

of the nasal aperture,
which, when a the neh)
they more readily raise
their nostrils to the atmo-
sphere for the purpose of
breathing.

forms a very important
office in the carnivorous
| group, as the zygoma re-

\ quires to be very exten-

sively developed for the
protection of the enormous masses of mus-
cle which are needed in tearing the food of
these animals, as well as for the attachment of
the masseter. ‘The zygomatic arch in this order
is convex upwards as well as curved outwards,
by which form a great increase of strength is
acquired in the direction of the muscular
force.

The lacrymal bone is said to be wanting in
the seals. I believe I have seen a trace of its
existence in a rather young cranium of Phoca
vitulinu. The remarkable vacancy which oc-
curs in some of this tribe in the orbito-temporal
fossa, between the frontal, the maxillary, and
the sphenoid bones, has been supposed by
Meckel to indicate the place which the lacry-
mal bone should occupy; but as this hiatus
does not exist in several species, in which the
absence of this bone is equally evident, this
supposition is probably not correct.

The inferior maxillary bone (7) follows of
course the general structure of the superior.
It is remarkably short in the typical forms of
the carnivora, and more elongated in the others,
lap capied in the bears. Indeed this bone,
ike the upper jaw, is shortened exactly in pro-
portion to the carnivorous propensity of the
animal. The ascending plate is also remarkably
developed, and offers a surface of great extent
for the insertion of the elevators of the lower

jaw.

The character of the vertebral column in
the Carnivora offers some interesting varieties
of form, depending principally on the degree
of exertion, of activity, or of flexibility re-
quired by the habits of the different genera.
The strength and size of the two first cervical
vertebre, the atlas and dentata or aris, have
already been alluded to. The first is exceed-
ingly broad and robust, with strong transverse

processes ; the second islong, with an enormous __

spinous process. The remainder of the cervi-
cal vertebre are generally rather elongated in
most of the genera, but in the seals they are short
and but little developed. In general, also, the
spinous processes are considerable, and either

em

The malar bone (h) per- ‘

_

CARNIVORA. 475

ndicular or directed rather forwards, par-
ticularly in the cats, the coatis, the badger, and
some others. In the dogs there are also small
inferior spinous processes. The dorsal region
varies much in its relative proportions with the
lumbar region and with the size of the animal ;
a point which will be more particularly alluded
to presently. The spinous processes are very
strong and strait, and directed backwards.
The number of the dorsal vertebra, and, con-
sequently, of the ribs, varies in the different
genera of the order, from thirteen, which is the
most common number, to sixteen, of which
we have an example in the Glutton (Gulo
articus).

The /umbar vertebre are remarkably strong in
almost all the Carnivora, though less so than in
some other orders. The spinous processes are
long and directed forwards, particularly in the
cats and dogs, The transverse processes are
also very large and strong; but the most im-
portant circumstance connected with the cha-
racter of these vertebre is the relative propor-
tions which exist between them and the dorsal
in different species, not so much with regard
to number, as to the proportional extent of the
two regions. In respecteven to number, the
variations of the lumbar vertebre are not in-
considerable; thus, the Ratel and the Hyena
have only four, whilst the cats and many others
have seven. But we find that in those species
which, from their habits, require great power
of springing, of rapid running, or of great
flexibility of motion, the relative extent of the
lumbar region is increased in proportion, Thus,
whilst in the Hyena the lumbar region bears
to the dorsal only the proportional length of
four and a half to fourteen, and in the Ratel of
three to eight and a half; in the Lion we find
it as fifteen to eighteen, and in the Panther, the
Wild Cat and the Civet, the extent of the two
regions is almost exactly equal. This is a con-
sideration of great importance, not in the
Carnivora only, but in the Ruminantia and
other orders, where the different groups are
found to vary much in their powers of spring-
ing and their general activity: for the propor-
tion of the lumbar to the dorsal regions will
invariably be found in exact accordance with
the extent of those powers.

The Sacrum is composed of several vertebra,
as in most other mammifera; in the present
order there are generally three or four, though
in the Brown Bear there are six (Cuvier says
five), and in the White Bear seven; in the
Coati there is but one, and in the Hyena only
two. The spinous processes of the Sacrum
are more developed in this order than in many
others. Cuvier observes that, in those animals
which, from their habits, occasionally rise upon
their hinder legs and hold themselves upright,
the Sacrum is broader than in others of the
same order, and he instances the Brown Bear
in the present order as an example.

The tail, consisting of the coccygeal vertebrae,
varies excessively amongst the Carnivora, and
this in many cases in the same family, and
with but little obvious relation to the habits of
the species. As a general rule it may be ob-

served that the most active, and those which
possess the most flexible spinal column, have
the greatest number of caudal vertebre. Thus,
while the Brown Bear has only about six, the
Lion has twenty-three, and the Panther twenty-
four.

In many of the Carnivora which have long
tails, the spinous processes are generally di-
rected from before backwards, but are always
very small, and exist only on the few anterior
vertebre of the tail. The middle and posterior
coccygeal vertebre are therefore more deve-
loped in length and become almost cylindrical,
excepting that they are thicker at each extre-
mity. As in other orders, the anterior portion
only of the tail conveys the spinal marrow,
the posterior being impervious. The most im-
perfect developement of this portion of the
vertebral column is found in the Seals, in
which generally it is only the first vertebra
which possesses even a trace of spinous and
transverse processes, the remainder being al-
most cylindrical, without even any enlargement
at each extremity.

- The ribs correspond in number with the
dorsal vertebre. Their curvature yaries con-
siderably both as regards the different portions
in the same species and the general form in
different groups. In many of the mammifera
the difference in this respect between the an-
terior and middle regions of the thorax is very
striking; this, however, is generally not so
much so in the present order, in which, as a
general rule, the anterior ribs are not less
arched than the others, The anterior ones,
however, are very much smaller and shorter
than the middle and posterior. The relative
number of true and false ribs would, a priori,
appear to have some relation to the degree of
rapidity or of flexibility in the animal’s move-
ments; and hence that those which leap or
swim would require greater mobility of the
thorax, and consequently a greater proportion
of false ribs. Now, although this is strikingly
the case with regard to some of the cetacea,
which have only from one to five fixed ribs,
and from ten to seventeen false, yet no such
rule is observable in the present order; the
Seal and the Lion having even a less propor-
tion of moveable ribs than the Bear and the
Glutton.

The sternum in the Carnivora does not vary
greatly in breadth in its different portions. It
is much more developed longitudinally in these
animals than in most others, and is scarcely
broader than it is deep. The anterior piece of
this bone in the Seals is remarkably long, and
is also moveable,

The shoulder, composed of the same ele-
ments as in the other mammifera, varies, how-
ever, considerably in the degree of develope-
ment of the bones of which itis formed. The
scapula is depressed and remarkably broad
from the anterior to the posterior margin, and
in some cases—as in the Badger especially,
and in some degree in the Bear—it assumes
almost a quadrate form. The spine of this
bone, which in the Seal is very small, is of
great size and strength in the bear tribe, par-

476
ticularly in the Badger. The acromion is small
and slight in all the true Carnivora, but in
those of the Insectivora which have true cla-
vicles, it is long and robust. The coracoid
process is generally present, but is wanting in
the seals. The clavicle in the whole of this
order is very slender, and must be considered
as merely rudimentary. In the Hyena and the
Dog it is extremely small; larger in the Mus-
telide, and still larger in the Cats. It is not
attached to the sternum or to the scapula, but
suspended, as it were, between these two bones,
generally occupying not much more than half
the space between them.

The humerus is in general rather slender,
long and nearly cylindrical when compared
with that of the Pachydermata, Ruminantia,
and some others. It is somewhat arched, and
the great tuberosity is very much developed ;
this bone is short and broad, the superior two-
thirds being widened from before backwards,
and the lower third from side to side.

The fore-arm is here, as in the other orders,
composed of the radius and the ulna. The
latter bone is generally placed immediately
behind the former, and they have but little
motion one on the other, excepting in the bear
tribe, whose habits require more freedom of
movement in thé anterior extremity. That
tendency to the expansion of the members into
instruments fitted for swimming, which is so
obvious in the Seals, is found to obtain in the
two bones in question, which in this family are
short, flattened, and very broad.

The carpus in this order offers a few pecu-
liarities which may be slightly glanced at. The
os scaphotdes and the os similunare form but
one bone, which is of considerable size. The
os pisiforme is much elongated, forming a little
spur or heel to the anterior feet, a peculiarity,
however, which is wanting in the seals. The
os trapezium is very small in the Hyena, in
which the thumb is but rudimentary.

The metacarpal bones in the digitigrade car-
nivora are much larger than in the plantigrade.
In the latter the shortness of these bones, with
the comparative length of the phalanges, gives
somewhat of a plantigrade character even to
the fore-feet, although the metacarpal bones do
not actually rest upon the ground: whilst in
the digitigrade families, and especially in the
cats, the metacarpals being much produced,
and the phalanges very short, the part which
rests upon the ground is greatly abbreviated.

The phalanges offer some very interesting
points of structure, particularly in the Felide, in
which the terminal phalanx is retractile, or, on
the other hand, can be thrust out and rendered
the basis of a most formidable weapon. This
character of the retractile claw is, in its
full developement, peculiar to the family just
named; and the ice may be selected as
offering, from its great size, the most conve-
nient opportunity for its examination. In all
the Carnivora the claw is fixed on the extremity
of the last phalanx (fig. 196, a, a), the hooked
form of this part of the bone being an accurate
model of the interior of the claw, and the base
of the claw is secured within a thin lamina or

CARNIVORA.

hood of bone which covers it on the sides and
above. In the animal just named this is par-
ticularly strong and large. It is considerable
also in the Badger, but less so in the Bears,
the Dogs, the Hyenas, &c., and in the Civets
it is very small. The penultimate phalanx is
of a peculiar form. Its transverse section
would be triangular, two of the sides being
lateral, and the third inferior. On the inner
face or side, there is a hollowing or twist of the
bone, which leaves an oblique excavation in
the middle. It is by the inferior portion of the
last phalanx that it is articulated to the penul-
timate, and beneath the joint a process of the
last phalanx extends downwards, for the at-
tachment of the muscles by which the toes are
flexed, and consequently the claw protruded.
When the claw is retracted or in a state of rest,
the last phalanx is brought upwards and thrown
completely hack on the inner side of the se-
cond phalanx, being partly lodged in the lateral
hollow before described. This is the condition
of repose, and the last phalanx is held in this
situation by the elasticity of the capsular liga-
ment, and particularly by two lateral ligaments
which arise from the second phalanx. ;

The posterior extremity.—The pelvis in the |
Carnivora is shorter than in many other orders, |
and the ossa ilii particularly are flattened and
rather broad. Their internal surface also is not
turned forwards as in most other orders, but |
for the most part directed towards the spine,
so that the ventral aspects of these two bones
face each other. In most of the seals the ilia are
short and small, compared with the other bones
of the pelvis. The posterior or descending
branch of the ischium, and the anterior portion
of the pubis are, in particular, much elongated
in this family.

The femur is strait, cylindrical, and mode-
rately long in most of the Carnivora. In the
Seals it is, however, extremely short, as may be
observed in fig.191. In this tribe this bone
does not assume the direct backward direction
of the leg-bones, but stands outwards and
downwards, by which a great extent of motion
is obtained for the hinder paddles.

The tibia and fibula,* (fig. 196, 1, m;
Jig. 197, i,k; fig. 198, l,m;) are detached in
most of the Carnivora; but in the Dog the
Jibula is attached to the back part of the tibia.
In the Phocide these bones are long, flattened,
directed backwards, and the tibia has a double
curvature. The tarsus consists of the same
bones in the Carnivora as in Man, (fig. 196,

Ss 8h, i, k, fig. 197, ¢, f, 8, h, fig. 198, f, g,h, k,)
the os calcis has a very long and robust tube-
rosity both in the digitigrade (fig. 196, k) and
plantigrade (fig. 197, h) forms. In the former —
there is also on the inferior surface a small
tubercle which is wanting in the others.

* The figures representing the hinder foot are }
selected for the purpose of shewing the three prin- 1a
cipal types of progression in the Carnivora. Fig.
196, that of the Lion, exhibits the digitigrade,
Jig. 197, that of the polar bear, the plantigrade;
and fig. 198, that of the seal ( Phoca vitulina,), the

natatory.

CARNIVORA.

The metatarsal bones (fig. 196, 197, 198, d)
are generally five. In the cats and the dogs,
indeed, the inner one is merely rudimentary,
a defect which is perfectly consonant with the
absence of a posterior thumb in these two
genera. Those of the seal tribe are remark-
ably longand slender. The first is the longest,
the fifth the next, then the second, the fourth,
and the middle one which is the shortest.

The toes consist of three phalanges (fig. 196,
197, 198, a, b, c,) and in most genera there are
five toes; the bears and other plantigrades
having the inner toe or thumb in the same
range as the others; in the mustelide it is a
little smaller, and in the cats and dogs it is
wholly wanting. The toes in the’seal tribe are
developed to considerable length, and being
much extended, and covered with an entire
skin which extends from one to the other, a
very perfect finlike paddle is thus furnished.

The types, then, of the three different varie-
ties of progression are here distinctly shewn.
_In the foot of the bear (fig. 197) we find that
_ every thing in its formation is made subser-
vient to the action of walking; the heel, the
tarsal and the metatarsal bones, and the pha-
langes all rest upon the ground, and these
bones are elongated for that purpose. In the
Lion (fig. 196) the last phalanges only rest on
the ground, the heel being drawn upwards, and
the whole of the foot, excepting that small
portion which is applied to the ground, is thus

made an additional lever for the increase of the

animal’s powers of leaping and bounding in
its course. In this form the limb consists of
three joints (the pelvis being the fixed point)
moveable in alternately different directions,
peepee of being all approximated to each

er, and then suddenly and simultaneously

477

extended with prodigious force. In the third
type, that of the Seal (fig. 198), the bones are
all much flattened, and, excepting the foot,
greatly shortened; the foot itself being de-
veloped both longitudinally and laterally into a
finlike expansion.

The Muscular System.—The general cha-
racter of the muscles in the Carnivora is that
of combined power and irritability. The ele
vators of the lower jaw, the masseters and the
temporals, are enormously large, for the pur-
pose of cutting and tearing the flesh and the
harder portions of their food. The muscles
of the face also, those of the lips, of the nose,
of the eyelids, and of the ears, are all of them
greatly developed and capable of the most
extensive and powerful motion. A moment's
reflexion upon the habits of these animals, and
particularly on those of the cats, will shew the
necessity of enormous power in the muscles
which raise the head upon the spine. A Lion,
it is said, can killa moderate-sized bullock, throw
it on his back by a toss of the head, and trot
off with it to his hiding-place. All the muscles,
therefore, which arise from the vertebre of the
neck and are inserted into the projecting ridge
of the occipital bone, are of prodigious strength.
The same remark holds good of all the muscles
of the limbs, particularly those of the anterior
extremity, but which do not require a par-
ticular description or demonstration. The mus-
cles of the tail, which are for the most part
similar in this order to those in the tailed Qua-
drumana and Ruminantia, will be described
in the articles devoted to the anatomy of those
animals.

The digestive organs.—The structure which
has been already detailed in the skeleton of the
Carnivora, and alluded to in their muscular

478

system, will be found altogether subservient to
the office of procuring that peculiar kind of
food to which these animals are restricted, and
the modifications of that structure which have
been described as appertaining to different
types of form in the order, are equally con-
sonant with the modified nature of their ali-
ment. Thus, whilst the powerful yet active
and flexible movements of the typical Carni>
vora are adapted only to the pursuit and de-
struction of living prey, the more sluggish habits
of most of the bear tribe, their peculiar mode
of progression, and the modified structure of
the skull, the teeth, and the limbs, are all
equally applicable to the mixed nature of their
food ; and the third principal type—that of the
amphibious carnivora, the Seals— exhibits an
arrangement of these organs not less admirably
fitted for the pursuit and capture of their
aquatic and scaly prey. The digestive organs
of each of these prominent groups are not less
perfectly formed for the digestion of their vari-
ous food, than the organs which have already
been described are for its capture. The teeth
have already been slightly alluded to, but they
deserve a more particular description. In the
cats, the character of the teeth is typically car-
nivorous. The incisores are very small, as
indeed they are throughout the whole order.
The canine teeth are, on the contrary, pre-
eminently strong, long and sharp, and are
evidently adapted for seizing and holding their
prey and afterwards tearing in pieces the flesh
and other soft parts of the animals. These
teeth are conical and very slightly curved,
a form which, united with their sharpness and
strength, is the best that can be imagined for
effecting this object. The cheek teeth, instead
of having flat grinding surfaces, have, for the
most part, only cutting edges; and those of
the lower jaw shut within the upper, passing
them so closely as to form an accurate instru-
ment either for shearing off pieces from the
flesh or for cutting into morsels the portions
which have been torn by the canine teeth.
‘On each of them are sharp triangular processes
which much facilitate the entrance of the tooth
into the flesh. The range of these teeth is
short, as is also the whole jaw, by which great

ower is gained in this particular direction.

he articulation of the lower jaw is also cir-
cumscribed to a perpendicular motion, the only
one which the structure of the teeth would
permit. The strong muscles of the lips also
enable the animal to raise them out of the way
of injury during this process. The animals of
the bear tribe, on the other hand, have an
elongated jaw, canine teeth, although very large
and strong, yet less so than in the cats, and
molares, the surfaces of which, instead of being
raised into cutting edges, are depressed, tuber-
cular, and require a certain degree of lateral
motion in the jaw to bring them into action.
In the seals a very different structure of the
teeth is observed. The canines are not par-
ticularly large and prominent ; and the molares,
neither adapted on the one hand for shearing
nor on the other for grinding their food, either
of which actions would be unavailable in their

CARNIVORA.

particular case, are numerous and furnished
with several angular points, which are fitted
for holding the slippery, scaly surface of fish,
and equally so for crushing them before they
are swallowed. The teeth of the Walruses,
however, are very different from those of man f
other of the Phocide. The tusks (fig. 195
which are enormous canine teeth of the upper
jaw, are directed downwards, and constitute
formidable weapons of defence, and the mo-
lares are formed rather for grinding than for
merely holding their prey.

The food then being thus variously prepared
by the different groups of this oral passes —
into the stomach more or less masticated.
The salivary glands in the meantime have been
performing their important office. The vari-
ations in form and situation of these glands
are slight and unimportant. The submaxillary
glands are generally as large as the parotid,
which in the dogs and cats are of a crescentic
form, embracing by their concave margin the
conch of the ear; and in the dogs the inferior
portion is distinct from the rest. The sub-
lingual are wanting in the cats.

The stomach in all the animals of this order
is perfectly simple, and its interior smooth,
with the exception of that of the Seal, which
has a villous coat. In the cats (that of the
Lion is shewn at fig. 199) it is elongated, and

eS. se ee ee

.

A

Payee oe ee

WB

Yyyf . pth lITTT Chap zy

Tae. a ee ee ee

the two openings are placed nearly at each end:
there is asmall pouch however at the cardiae re
extremity. In the Wild Cat it is somewhat
yriform, the pyloric portion being, as in the
Sms doubled upon the other part; and in the
Lynx the cardiac and pyloric openings are
more distant than perhaps in any other species.
In the other genera the form varies alittle.
It is nearly globular in the Racoon; thatofthe __
Hyena is large and short. In the seals it is”
elongated from before backwards, the pyloric
portion being turned forwards upon the other;
at the bend there is a pouch, at which pointa —
glandular layer is found between the internal —
coat and the cellular. 4
The intestinal canal is in these animals re-—
markably short, particularly in the cats; in the
Lion and in the Wild Cat the whole alimentary —
canal is but three times the length of the fs
In the Seal it is much longer. The distinction —
between the small and large intestines varies —
considerably In the Badger this distinction —
can scarcely be said to exist: in the Lion itis —
considerable, and still more so in the seals and —

a 5

CARNIVORA.

others. The cecum exists, but is very small
and short in the cats: (fig. 200 shews that of
the Lion.) In
the dogs it is spi-
ral. The whole
canal is almost
destitute of val-
vule conniventes,
nor is the large
intestine tucked
up into sacs as
in other orders.
The mustelide
generally have no cecum nor valvula coli.

A short comparative view of the structure
thus hastily sketched, with that of the digestive
system in the typical herbivora, the ruminant
animals, will not be uninteresting. The Car-
nivora feeding on aliment which requires but
little elaboration to convert it into nourish-
ment, the whole process of digestion appears to
be as rapid as possible, and we find that every
part of the organisation is admirably adapted
to this object. The strength of the jaws, the
form of the teeth, the structure of the maxillary
articulation are all contrived for preparing the
food by simple division. The stomach is sim-
ple and almost straight, the intestines short, and
without any structure to retard the passage of
the food. In the ruminantia, on the contrary,
the jaws are much elongated, the molar teeth
flat and formed for affording the greatest pos-
sible extent of triturating surface, the maxillary
joint allowing of the most extensive lateral mo-
tion, the stomach complicated, and a second
and more complete mastication is performed
after the food has been long macerated in the

unch. The intestines are exceedingly long,
fin the ram twenty-eight times the length of
the body,) very large, and tucked up into folds

sacs throughout their whole length. Here
every thing is arranged for the thorough com-
minution and maceration of the food, and for
the greatest possible retardation of its passage
through the body, as well as for an immense
extent of absorbing surface for the extraction
of every particle of nutritious matter.

The liver in the Carnivora is deeply divided
into lobes, which vary in number in different
species. Thus in many of the plantigrades
there are five, as the brown bear, the coati,
and the racoon; in the otter also, and in the
martens and generally in the dogs there are the
same number. The Badger has but four. The
cats generally have from five to seven, though
that of the jaguar has but-four, and that of the
lynx eight. This numerical variation appears,
therefore, to have no reference to any physio-
logical law, nor to any peculiarity of habit.

The hepatic ducts offer some peculiarities
worthy of notice. In the cats there are always
several, which correspond with the different
lobes of the liver. Before the ductus com-
munis opens into the duodenum after passing
the muscular coat of the intestine, it forms a
considerable enlargement, divided by an in-
ternal contraction into two cavities, into the
first of which the pancreatic duct opens. In
the dog the ductus communis enters the intes-

479

tine with one of the pancreatic ducts. In the
otter, the common duct forms a second reser-
voir near the duodenum.

The gall-bladder exists in all the Carnivora.
It varies in some measure in form, being py-
riform in most, elongated and almost cylin-
drical in many of the mustelide, and rounded
in the bear, the racoon, and some others. It
is of great size in several of the plantigrades.

The pancreas is similar in its general struc-
ture to that of the other mammifera. It varies
in form, but not in any way that can be sup-
posed to give it a peculiarity in function. The
pancreatic ducts vary also in number and in
the situation at which they open into the liver.
In some instances, as in the cats, the pan-
creatic and common biliary ducts are united
and enter the intestine at one orifice, though
this circumstance is not uniform in the genus,
nor even in all individuals of the same species.
As a general rule in this order the ducts of
these two important glands terminate together.

The spleen requires also to be merely glanced
at, as its characters and situation do not ma-
terially differ from those in the other orders
of the class. It is generally elongated and
narrow, and either flattened or somewhat pris-
matic.

The chyliferous system.—The chyle in the
Carnivora has always been remarked for its
whiteness and opacity, a circumstance which
greatly facilitates the tracing the course of the
lacteals in this order, and which in fact gave
rise to their discovery in these animals before
they were seen in man. The mesenteric glands
are united either into one large mass only,
as in most examples of the order, into two as
in mustela, or the larger substance is associated
with several smaller ones, as in the cats, the
otter, the seal, and some others. This glan-
dular mass has been termed Pancreas Asellii,
from its having been erroneously mistaken for
a pancreas by that anatomist.

The thoracic duct in the dog is double,
and in the Sea Otter it has been found by Sir
Everard Home that two ducts go from the
receptaculum chyli to form this duct, which in
its course sometimes divides into two, three, or
four, again uniting at intervals.

Organs of circulation.— The heart and blood-
vessels offer but few peculiarities in this order
worthy of particular notice. The heart varies
but little in form; its parietes are remarkably
strong in the larger cats, in the lion particularly.
The general structure of this viscus does not
differ materially from that of the other mam-
mifera. There is, however, a question of some
interest which has been often debated ; this is,
whether the foramen ovale and the ductus
arteriosus remain pervious in the seals and the
otter. The testimony of Cuvier and of Blumen-
bach goes to prove that, at least in many in-
stances, these openings are closed. Cuvier
states it to have been so in a seal, and Blumen-
bach says that this is its general condition.
On the other hand Sir Everard Home has
given two examples in which the foramen ovale
remained pervious in the sea otter; Blumen-
bach also states that he possesses the heart of

480

an adult seal, in which both these channels of
communication remained open; and the writer
of this article dissected a seal some years since
which was nearly full grown, in which the
foramen ovale was so open as to allow the
tip of the little finger to enter, and the ductus
arteriosus would admit with ease the bulb of a
common probe.

Upon the whole then it appears that, al-
though the pervious condition of these chan-
nels cannot be considered as general in the
adult state of these diving animals, as has
sometimes been supposed, it must be allowed
that this exception is far more frequent in them
than in any other mammiferous animals, and
that, as a general rule, these holes remain open
later in such animals than in others. There is,
however, in the otters and in the seals, a con-
siderable dilatable enlargement observed in the
inferior cava, which serves doubtless as a re-
servoir to retain part of the returning blood
during submersion, until the animal rises again
to breathe.

Organs of respiration.—The lungs are di-
vided into lobes varying but little in number
in the terrestrial families of the order. These
all have four lobes to the right lung, and either
two or three to the left. The seals have the
right lung divided into two lobes, and the left
undivided.

The cartilaginous portions of the rings of
which the trachea is composed vary in the
proportions which these bear to the whole
circle; in the genus Mustela and some others,
the cartilage forms about two-thirds of the
circle; in the bear, the coati, and the cats,
about three-fourths; and in the ichneumon as
much as four-fifths.

The nervous system.— On viewing the dif-
ferent orders of mammifera in the ascending
series, the brain of the Carnivora (fig. 201
being an upper and a lateral view of that of the
Lion) will be found to exhibit a higher degree

Fig. 201.

of developement than exists either in the
cetacea, in any of the forms of the herbivora,
or in the marsupiata; the hemispheres have
here a well-marked superiority of develope-
ment over the cerebellum and tubercula quadri-
gemina. On the other hand the brain of the
Carnivora is less developed anteriorly than in
the Quadrumana, the anterior lobes being some-
what narrowed and depressed, and the con-
volutions, (although deeper than in the orders

CARNIVORA.

ust mentioned,) instead of the labyrinthine
pipet ass which are observable in the Qua-
drumana and in man, are, generally speaking,
longitudinal in their direction, the aoe
being but two on each side of the median line,
crossed by a transverse anterior one. The
cerebellum is almost wholly uncovered as seen ;
from above, not more than one-fifth of it lying
under the posterior edges of the hemispheres.
The optic thalami, however, are concealed not
only from above but even ona lateral view,
by the hemispheres. Of the tubercula qua-
drigemina, the posterior are the larger.

The eye possesses but few peculiarities of
any importance. The relative proportions of
the different humours are here more nearly
equalized than in any order of the mammalia,
at least in some of the genera, as the following
comparative view will shew :—

Aqueous, Crystalline. Vitreous.

Dog ode a S Seg eee
Mae). es ss Pee
Oxs easly a as eae

The vitreous humour, therefore, is much less
than in either of the other cases, and the erys-
talline smaller in proportion than that of man.
The crystalline lens in the Seal fulfils the gene-
ral law which gives to it a degree of sphericity
in relation with the aquatic habits of the
animal. Thus the crystalline of fishes is ab-
solutely spherical, that of the cetacea nearly so,
and that of the seal and of the otter very much
less flattened than in those animals which re-
side and seek their food on land. In the seal
also the sclerotic is considerably thickened
anteriorly and still more dense at the posterior
part, whilst the middle zone is very thin and
flexible-— a structure which must offer great
facility for the action of the different muscles
which compress the globe, and alter the rela-
tive proportion of its diameter to its axis. The
form of the pupil differs in different groups.
In the diurnal carnivora, and even in some
nocturnal, it is permanently round ; but in the
cats it is perpendicular during its contracted
State, and in a very bright light it is almost
linear, but even in these it becomes perfectly
round in the dark, and the ellipse which it
forms in its contraction is more or less length-
ened or acute according to the degree of light.
The inner surface of the choroid is partially
lined with a brilliant greenish tapetum, similar
to that which is found in the ruminantia, and
occupying nearly the same situation.

The lachrymal gland exists throughout this
order, and the glandula Harderi is also found
in its members as well as in the ruminantia,
pachydermata, and some if not all the ro-
dentia. .
Lhe organ of hearing is developed to a very —
considerable degree in most of the Carnivora. —
The external ear varies much in size and form;
it is moderate in the cats, small in the bea
and rudimentary in the seals, but enormov
large in the Fennec, a species of the family —
Canide. There is in these, as well as in many —
other mammiferous animals, especially the ro- —
dentia, a remarkable hollow appendage to the —

i
4

CARNIVORA.

true tympanum, taking the place of the mastoid
process, and probably performing the same
office as the mastoid cells. This, in many,
forms a large rounded process beneath the
cranium. In the cats it is remarkably large
| and globose; in the bear, on the contrary, it is
: not visible externally. The object of this en-
larged cavity is doubtless to give additional
volume to the sounds which are brought to it,
a circumstance especially required by the noc-
turnal habits of those species in which it is
most largely developed. The Jenestra rotunda,
which is covered by a membrane stretched
across it, is believed by Cuvier to be intended
for the reception of the sounds produced by
the resonance of the bony case just described ;
an opinion which is perfectly consonant with
that of Scarpa, who considers the hole in
question, with its membrane, as a sort of se-
condary tympanum. The fenestra rotunda is
the larger of the two apertures of communi-
cation with the internal ear in the present order
generally; in some of the most nocturnal, the
cats and the civets, it is almost double the size
of the fenestra ovalis. The passage answering
to the Eustachian tube is remarkably short and
can scarcely be called tubular; in the cats and
civets it is nothing more than a narrow cleft in
the suture which unites the tympanum to the
true petrous bone.

The organ of smell is generally extensive in
the carnivorous animals, and in addition to the
principal apparatus of this sense, the different
sinuses which augment the nasal cavity, par-
ticularly the frontal, are of considerable extent,
especially in the canide. But the most re-
markably developed of the surfaces on which
the pituitary membrane is distributed, are
those of the superior and inferior turbinated
bones. ‘The inferior are very complicated in
their convolutions in the dogs, the bears, seve-
ral of the cats, and particularly in the otters

and the seals. This complication consists of
repeated and multifarious bifurcation ; and the
ultimate divisions of this bone, which all as-
sume a parallel direction, form a great number
of channels which the air traverses in the act
of inspiration, and which are all covered by
the pituitary membrane. The ethmoidal cells
_ and the superior turbinated bones are likewise
_ greatly developed in the Carnivora, and par-
ticularly in those in which the before-men-
tioned structure of the inferior turbinated
_ bones is most conspicuous—a remark which
_ also applies to the numerous foramina in the
cribriform plate of the ethmoid.

In the bear, and particularly in the coati,
the cartilages of the nose form a complete tube,
_ which is articulated moveably to the bony nos-
trils. The same structure is still more remark-
_able in the mole.

The organ of taste—The structure of the
surface of the tongue in the Felide is very
temarkable with regard to the characters of the
various papille with which it is furnished. The
_ edges are everywhere covered with small soft
_ conical papille, as well as with the papille
_ petiolate, such as are found in most other
: VOL. I. .

481

animals. The whole of the middle part is
covered with papilla of two kinds very dif-
ferent from each other, and these two kinds are
arranged in alternate rows in a quincuntial
order. Those of one kind are soft, rounded,
and appear to consist of bundles of filaments,
which are supposed by Cuvier to be the ulti-
timate extremities of the gustatory nerves,
though this opinion appears from the recent
observations of Breschet to be very doubtful.
The others are conical and pointed, and each
of them is covered by a sharp horny case
curved a little backwards. It is these horny
spines which render the tongue of the cats and
the civets so exceedingly rough as that their
continued licking would soon abrade the hu-
man skin. The tongue in all the other Carni-
vora scarcely differs in its structure from that
of the human subject.

Secretions.— The urine. The structure of
the kidney in some of the Carnivora is wor-
thy of notice. Instead of being a compact
and united mass as in man, it is subdivided
into numerous portions similar to those of the
human fetus. In the cats this division is
scarcely perceptible, the surface being only in-
terrupted by superficial fissures or sulci. But
in the bears, the otters, and the seals, the sepa-
ration is so deep as to resemble in some sort
a bunch of grapes. In the otter there are only
ten of these divisions in each kidney; in the
bear there are about fifty, and in the seal from
a hundred and twenty to a hundred and forty.
As this peculiarity of structure is found to
exist in a still more remarkable degree in the
cetacea, Cuvier has suggested whether it may
be connected with the occasional longer or
shorter suspension of respiration, as it obtains
in the cetacea, the seals, the otters, which
are often submerged, in the bears which re-
main torpid during the winter, and in the
human fetus which has never breathed. Its
existence, however, in the elephant, the ox,
and many other animals whose respiration is
never interrupted, renders this explanation,
as Cuvier himself observes, extremely unsatis-
factory.

The existence of follicles producing a pecu-
liar secretion is not an uncommon circumstance
in several orders of the mammifera, as well as
in many reptiles. In the Carnivora these fol-
licles are found in almost all the genera, and
in some attain toa large size. They are situ-
ated one on each side of the anus, and the
excretory duct opens near the termination of
the rectum. The substance usually secreted
by these glandular surfaces is strongly odor-
ous, and in some cases intolerably fetid. The
annexed engraving (fig. 202) is taken from
a specimen of Gallictis vittata, which I dis-
sected some time since, and is selected,
because it has not been before figured, and
because the glands are of large size and very
distinct. Each follicle is covered by a muscle
of no inconsiderable strength, the object of
which is to compress the follicle, and to
force out the secretion through the duct. One
of the follicles is represented covered by its

21

482

muscle; the other has had the muscle re-
moved.

Besides these follicles there is in several
species a pouch, somewhat resembling those
above described, but differently situated. It is
always single, and in the badger and hyena is
placed between the anus and the tail; in the
ichneumon it surrounds the anus, and in the
civet it is found between the anus and the
opening of the prepuce in the male, and be-
tween the anus and the vulva in the female.
The secretion of this sac in the latter animal is
well known as a scent of a most powerful
musk-like odour. The sac opens by a longi-
tudinal slit, and in the interior are seen two
cavities in which the substance is secreted, and
which are furnished with a muscular coat for
its expression.

Generative system.— Male organs. The
structure of the testes is similar to those of the
other mammiferous animals, but they vary con-
siderably in situation. In most of the genera,
as in the bears, the cats, the martens, the hy-
enas, the ichneumons, &c. they are perma-
nently suspended in a pendulous scrotum. In
the civets they are enclosed under the skin of
the perineum, and in the otter under that of the
groin. In the seals, in which a pendulous
scrotum would be exposed to continual danger
of injury or destruction, they remain con-
stantly within the abdomen, being retained in
their situation by a production of the peri-
toneum, resembling the broad ligaments of the
uterus.

The vesicule seminales do not exist in most
of the Carnivora. They are found in the
coatis, but not in their congeners. The pros-
tate gland, or at least a glandular body ap-
parently analogous to it, is found throughout
the order. It varies in form and exceedingly
in size; in the otter and the other mustelide@ it
consists of a thin layer only, whilst in the dogs
and cats it forms a large and conspicuous bulb
around the urethra.

Cowper’s glands also are found in many of
these animals, but are wanting in the planti-
grades, in the mustelide, the dogs, and the
seals. In the Felide (the cats and the civets)

CAROTID ARTERY.

and still more in the hyena, they are on the
other hand of great size, and the muscle which
envelopes them is of considerable thickness. _

The penis is found to vary but little in its
form and direction in this order. It is, in al-
most all, directed forwards, and contained
within a sheath formed of an extension of the
integuments of the abdomen. In the cats
the extremity, during its relaxed state, is turned
backwards, and the urine is consequently
voided in that direction, but during its erect
condition it assumes the same position as in
the other Carnivora. Almost the whole of the
carnivorous order possess a bone of the penis,
of various size and length. The hyena is a
remarkable exception, as in its congeners, the
dogs, &c., it is of considerable size. This is
the case also with the urside and the mustelide ;
but in the cats and the ichneumon it is small.
The anterior extremity of this bone is fixed in
the glans, and the posterior is attached to the
corpus cavernosum. In some genera, particu-
larly the dogs, the corpus spongiosum wnder-
goes a remarkable degree of tumefaction, which
retains the two sexes in coitu for a considerable
time.

The female organs.—The clitoris is found in
all the Carnivora. It is contained in a sort of
pouch within the vulva in the wolf, and at
some distance in front of this part in the civet.
In some of those species in which the penis
of the male is furnished with a bone, the clitoris
of the female has also a rudimentary one.
This, however, is not constant. It is not found
in the dogs or civets, but exists in the cats, the
bears, and the otter.

The uterus is two-horned, and resembles that
of most other mammifera.

The mammary glands are situated along the
sides of the belly, and the number of teats
varies greatly, without any general law as
regards the affinities of the species. Most of
the plantigrades have six; but the lion has
four, the cat eight, and the panther six; the
bitch, again, has from eight to ten.

The placenta consists, in the cat, the dog,
the marten, and others, of a perfect zone sur-
rounding the foetus, and attached by its whole
external surface to the uterus; in the polecat
it is formed of two rounded masses connected
together.

|
:
:

For the BIBLIOGRAPHY, see that of MAMMALIA.

(T. Bell.)
CAROTID ARTERY, (human anatomy,)

(arteria carotis; Gr. xagwtss; Fr. carotide; —
Germ. die Carotis, Kopfpulsader;) the great —
artery which on each side distributes blood to —
the different parts of the head. The term ~
carotid, derived from xapog, sopor, appears to —
have been first applied to the arteries of the —
head by the ancients from a supposition that a —
state of drowsiness or deep sleep depended
compression or some other affection of the
vessels exercising an influence over the circ
tion of the blood in its passage through
to the brain: in accordance with the sé

i.

CAROTID ARTERY.

opinion they
soporifere, B

_ The carotid arteries consist of—1st, the pri-
mitive carotids, of which the right arises from
the arteria innominata, while the left comes
directly from the arch of the aorta; 2d, the ex-
ternal carotid ; and, 3d, the internal carotid:
_these last two vessels on each side being pro-
duced by the bifurcation of the primitive ca-
rotid.

Both primitive carotids are of equal size
according to Bichat, Boyer, and Cloquet; uei-
ther Meckel nor Tiedemann make any remark
as to a difference in their size, while, according
to Soemmerring, the right is one-twenty-fifth
larger than the left in the majority of in-
stances.

The origin of the right carotid from the
arteria innominata is opposite the right sterno-
clavicular articulation. The left carotid arises
from the transverse portion of the arch of the
aorta behind the first bone of the sternum, on a
plane with the centre of the junction of the
cartilages of the first pair of ribs with that bone
in front, and corresponding with the superior
edge of the second thoracic vertebra posteriorly ;
Owing to this difference in their origins, the left
primitive carotid is from one inch to one inch
and a quarter longer than the right, and is con-
tained within the thorax in the commencement
of its course; it may therefore be divided into
a thoracic and a cervical portion.

The thoracic portion of the left primitive
carotid, by which I mean that portion which
extends from the origin of the artery to a point
ona level with the sterno-clavicular articulation,
has the following relations :—anteriorly it is
covered by the left vena innominata, the remains
of the thymus gland, some loose cellular tissue,
and occasionally a few lymphatic glands; in
front of these the origins of the sterno-thyroid
and sterno-hyoid muscles separate it from the
sternum ; posteriorly it rests on the cesophagus,
left recurrent nerve, the origin of the left sub-
clavian artery, the left par vagum, the thoracic
duct, and some loose cellular tissue, in addition
to which the longus colli is interposed between

have been also called arterie

itand the front of the spinal column; on its

right side it is bounded by the trachea, and on
its left by the peice nerve and the mediasti-
nal portion of the left pleura, which gives a

covering to a small portion of its surface,
against which the internal side of the apex of

the left lung is applied.

The right primitive carotid and the cervical

_ portion of the left are of equal length, and have
_ Similar relations: at first, in the lower part of
the neck these vessels of opposite sides are only
_ separated by the breadth of the trachea: as

_ they ascend, however, they diverge from each
_ other, and are separated by the larynx and

_ thyroid body : in their ascent they seem to pass

C
aa

wards, owing to the prominence of the

‘ shag forwards, but in reality they cannot re-

de, as they are closely applied to the front of

_ the spinal column; they are not contorted in

course, nor do they furnish any branch
until they arrive as high as the superior margin

483

of the larynx, where each bifureates by dividing
into the external and the internal carotids.

Relations of the trunk of the Primitive
Carotid.—Anteriorly the primitive carotid is
covered by the three following layers of mus-
cles from the sterno-clavicular articulation to
the level of the cricoid cartilage; 1st, the pla-
tysma myoides, beneath which lies the superfi-
cial layer of the cervical fascia; 2d, the sternal
portion of the sterno-cleido-mastoid ; and 3d,
by the sterno-hyoid, sterno-thyroid, and the
omo-hyoid, which latter muscle crosses the
sheath of the artery, having its internal edge
connected with the outer edge of the sterno-
thyroid by a dense fascia, a part of the deep
layer of the cervical fascia, which is firmly con-
nected to the posterior margin of the clavicle
inferiorly: between the lower part of the sterno-
mastoid and the front of the artery there is an
interval of about an inch on the left side, and
something less on the right, in consequence of
the origin of the right carotid being so much
more anterior on that side; this interval is
filled by cellular and adipose tissue, some large
Veins, one or more of the sub-clavicular branches
of the cervical plexus, and occasionally a few
lymphatic glands; at the level of the cricoid
cartilage the sterno-mastoid passes backward,
and the omo-hyoid coming from beneath, it
passes forwards to its insertion into the os
hyoides. Above the crossing of these two
muscles the carotid has no muscular covering,
except the platysma, from which it is separated
by cellular membrane, several veins from the
thyroid body and larynx, and some lymphatic
glands; the nervus descendens noni also lies in
front of the primitive carotid at its upper por-
tion, being found sometimes within, sometimes
outside, and occasionally embedded in the sub-
stance of the wall of its sheath; the thyroid
body also generally overlaps the carotid by its
outer edge.

Posteriorly the carotid is bounded by the
longus colli and rectus capitis anticus major,
which separate it from the anterior surface of
the spinal column; the cervical cord of the
sympathetic nerve and its superior and middle
cardiac branches are closely connected to the
posterior part of its sheath; the vertebral artery
and vein are behind it at its lower part; and
higher up it crosses the inferior thyroid artery
at a point corresponding to that at which it is
covered in front by the omo-hyoideus ; some-
times the inferior thyroid crosses over the ca-
rotid : the arteria cervicalis ascendens often lies
behind the carotid towards the upper part of
the neck; moreover, the recurrent nerve on the
right side, in its course from behind the sub-
clavian artery to the side of the trachea, passes
behind the origin of the right carotid. From
the relations of the primitive carotid posteriorly,
it is evident that it can be most effectually
compressed against the front vf the spinal co-
lumn, but to continue such pressure for any
length of time would obviously be followed by
injurious effects, from the lesion to which the
nerves behind the sheath of the vessel would

be thus subjected.
212

484

Externally the carotid artery is bounded by
the internal jugular vein and the pneumo-gas-
tric nerve, both of which are contained within
its sheath ; the vein when distended advances
1n front of it and partly conceals it ; the nerve
lies in the posterior part of the sheath, behind
and between the artery and vein, more closely
attached to the latter vessel; on the left side
the internal jugular vein lies closer to the ca-
rotid, in front of which it passes at the lower
part of the neck in its course to the vena inno-
minata; on the right side the jugular vein is
separated from the carotid inferiorly by a small
intervening space, principally occupied by cel-
lular tissue, in consequence of the vein of this
side descending to join the commencement of
the superior cava in a perpendicular course
further from the mesial line than the point at
which the carotid is given off from the arteria
innominata.

Internally the carotid is bounded by the
trachea at its lower part; higher up by the
thyroid body and the inferior constrictor of the
pharynx, by which it is separated from the
cricoid and thyroid cartilages; the recurrent
nerve also lies on its inner side, but separated
from it by a quantity of loose cellular tissue ;
in addition to the foregoing relations, the left
,carotid lies in contact with the cesophagus.

The varieties to which the origins of the
carotid arteries are subject are the following :
1. the right carotid sometimes arises separately
from the aorta ; this variety occurs when there
are four large trunks arising from the arch of
the aorta, of which the right carotid is the first,
and the right subclavian the last in order; 2.
sometimes the arteria innominata gives origin
to the left carotid, in addition to the right ca-
rotid and right subclavian, in which case the
left carotid has to cross in front of the lower
part of the trachea to enter upon its cervical
course; 3. the right and left carotids some-
times spring from a common trunk, which
arises from the arch of the aorta between the
right and left subclavian arteries; in this variety
as well as in the preceding, the situation of the
carotids in front of the trachea exposes them to
the danger of being wounded in the operation
of tracheotomy, in performing wnich the sur-
geon should always be prepared to meet with
the existence of such irregularities of distribu-
tion: 4. the left carotid sometimes arises from
a left arteria innominata, which also gives off
the left subclavian. (See Aorta.)

The bifurcation of the primitive carotid most
frequently occurs opposite the superior margin
of the thyroid cartilage, in front of the third
cervical vertebra; it may, however, take place
above or below that point. It sometimes bifur-
cates opposite the cornu of the os hyoides, or,
which rarely happens, behind the angle of the
lower jaw; in cases where the bifurcation is
higher than usual, the primitive carotid often
furnishes some of the branches ordinarily
arising from the external carotid. The high
bifurcation is an approximation to that condi-
tion of the carotid in which no bifurcation
takes place, but where the primitive carotid,

CAROTID ARTERY.

A ee

after having given all the branches which the _
external carotid usually supplies, enters the
cranium and becomes the internal carotid.

2. The primitive carotid sometimes bifurcates
lower down in the neck than usual. I have
seen such a bifurcation occurring on both sides —
in an old female subject, as low as the inferior

border of the thyroid body. ee

The bifurcation of the carotid has the same _ :
relation to the larynx at all periods of life: it
is more distant from the angle of the jaw in
the infant than in the adult; the depth of the
lower jaw in the former being much less, owing
to the non-development of the roots of the
teeth and alveolar processes: in old persons
who have lost their teeth, and whose alveolar

rocesses have been absorbed, the jaw being
in the edentulous condition, the angle of the
jaw is carried forward and thus removed farther
from the bifurcation of the carotid. By de-
pressing the head the angle of the jaw is
brought nearer to the bifurcation; while the
distance between these parts may be consi-
derably increased by throwing the head back-
wards.

The bifurcation of the primitive carotid gives
origin to the external and internal carotids ;
the former of these supplies the larynx, thyroid
body, pharynx, throat, face, and external parts
of the head; the latter is distributed to the
brain and the internal parts of the organs of
hearing and vision. These two vessels lie close
together at their origins. The internal is at
first more superficial and more external in
situation than the external, but becomes the
more deeply situated of the two as they ascend.
They are nearly of equal size in the adult when
the bifurcation occurs at the usual place; while
in the infant the internal is larger than the
external.

THE EXTERNAL CAROTID, (arteria carotis
externa, superficialis vel anterior, Samm. fa-
ciale of Chaussier,) extends from the bifurca-
tion of the primitive carotid to the neck of the |
condyle of the lower jaw, where it terminates
by dividing into the superficial temporal and
internal maxillary arteries. In this course it
describes a curve, the concavity of which is
outwards and a little backwards, as it ascends
between the ear and the ramus of the lower
jaw. At first it is superficial, merely covered
by the integuments, platysma and cervical
fascia; it then ascends under the ninth or
hypoglossal nerve and the posterior belly of the
digastric and stylo-hyoid muscles, and buries
itself in the substance of the parotid gland. In-
ternally it rests at first on the commencement of —
the internal carotid, then over the middle con- —
strictor of the pharynx, the stylo-pharyngeus
and stylo-glossus muscles, the glosso-pharyn- —
geal nerve and the styloid process of the tem=
poral bone; the superior and inferior pharyn- —
geal nerves coming from the par vagum also
pass under it in their course to the pharynge
plexus. The part of the parotid gland whiel
the external carotid first enters is the internal
surface of its lower extremity, consequently
the whole thickness of the gland covers it at —

CAROTID ARTERY.

that part; but in passing through the gland
the artery becomes more superficial as it ascends
and is covered only by a very thin layer of the
glandular substance at the place where it ter-
minates. The branches of the portio dura
forming the pes anserinus cross the course of
the carotid in the substance of the gland, being
superficial to it and separated from it by the
posterior facial vein and part of the glandular
substance.
Branches of the external carotid.*—The ex-
ternal carotid gives off eight principal branches;
three anteriorly, the superior thyroid, the lin-
gual, and the labial or facial; two posteriorly,
the occipital and posterior aural ; one internally,
the ascending pharyngeal ; and two superiorly,
the superficial temporal and internal maxillary,
besides several smaller branches, the number
and origins of which are subject to great
irregularity, and which are distributed to the
Sterno-mastoid muscle, the superior cervical
ganglion of the sympathetic nerve, the digastric,
Stylo-hyoid, stylo-pharyngeus, and stylo-glos-
Sus muscles, &e., to the parotid gland, the
external ear, and to the integuments.
ANTERIOR BRANCHES.—1st. The superior
thyroid artery (A. thyroidea superior) gene-
rally arises opposite the cornu of the os hyoides
a few lines above the bifurcation of the primi-
tive carotid ; in some rare cases it comes from
the trunk of the primitive carotid: it has been
also seen to arise from the lingual. It takes a
tortuous course downwards and forwards, and
passing under the omo-hyoid, sterno-thyroid,
and sterno-hyoid muscles, arrives at the supe-
rior and external part of the thyroid body to
which it is chiefly distributed: at first it is
superficial, being covered by the integuments,
platysma, cervical fascia, some lymphatic glands
and small veins coming from the superior part
of the larynx to join the internal jugular; it is
also crossed by the branch of the nervus de-
Scendens noni which is sent to the superior
belly of the omo-hyoid muscle, and the supe-
rior laryngeal and several filaments from the
Bee psnctic nerves to the larynx, &c. lie be-
neath it. In its course the superior thyroid
artery, besides furnishing a variable number of
ae branches, to the muscles and other
m its vicinity, generally gives off the
three following: a. The iiioidean ater which
runs along the inferior border of the os hyoides
between the hyo-thyroid muscle and the mem-
brane of the same name, to both which it gives
branches ; it inosculates with the corresponding
artery of the opposite side in the mesial line,
and with the lingual by a twig which passes up
on the front of the body of the os hyoides.
The hyoidean branch is often absent. 6. The
ners cial branch passes downwards and out-
wards over the sheath of the carotid artery to
the sterno-mastoid muscle, to which and the
neighbouring lymphatic glands and integu-
ments it is finally distributed, anastomosing

* In the arrangement of the branches of the
external carotid artery the writer follows that of
Meckel. See his Anatomie Descriptive, &c. trans-
lated into French by Breschet and Jourdan,

485

in the substance of the sterno-mastoid with
branches coming from the occipital above and
others from the thyroid axis inferiorly. c. The
laryngeal often arising from the external carotid,
an occurrence which, according to Meckel,
takes place in one case in eight, passes into
the larynx through the hyo-thyroid membrane,
sometimes through a hole in the thyroid carti-
lage; it usually accompanies the superior
laryngeal nerve: its branches are lost in the
internal muscles and mucous membrane of the
larynx and the epiglottis. Before it enters the
larynx it gives branches, some of which ascend
to anastomose with the hyoidean, others de-
scend to the thyroid body; one of these latter
is remarkable for running across the front of
the crico-thyroid membrane to anastomose with
a similar branch from the opposite side; it
generally lies in the situation in which laryn-
gotomy is performed. Having given off the
above-mentioned branches, and arrived at the
superior extremity of the thyroid body, the
thyroid artery divides into two branches, one
of which descends along its external edge,
sending off numerous branches which are lost
in its substance, anastomosing freely with the
inferior thyroid, the other branch descends
coursing along the superior border of that body
on which it expends its branches, and arriving
at the mesial line below the cricoid cartilage,
anastomoses with the corresponding artery from
the opposite side: occasionally this brarch
supplies the small artery which crosses the
crico-thyroid membrane.

2. The Lingual Artery (A. lingualis ) arises
after the thyroid, and sometimes, but rarely,
from a common trunk with the thyroid, comes
at other times and not unfrequently from the
facial. This artery forms in its course a con-
siderable curve, the convexity of which is
upwards ; it passes forwards and inwards above
the cornu of the os hyoides, between the mid-
dle constrictor of the pharynx and hyo-glossus,
and mounts up towards the base of the tongue,
between the hyo-glossus and sublingual gland
which lie to its outer side, and the genio-glossus
which is internal to it; then taking a horizonta!
direction, it passes forwards under the name of
ranine artery, in company with the hypo-glossal
nerve, coursing between the genio-glossus and
lingualis muscles, as far as the point of the
tongue where it anastomoses with its fellow of
the opposite side. After its origin and before
it passes under the posterior edge of the hyo-
glossus muscle, this artery runs superficially be-
neath the common coverings of the neck, lying
on the middle constrictor of the pharynx above
the cornu of the os hyoides; superior to it lie
the tendon of the digastric muscle, the stylo-
hyoid muscle and the hypo-glossal nerve,
which after sending a filament across it to the
hyo-thyroid muscle, continues its course for-
wards on the cutaneous surface of the hyo-
glossus muscle which separates the lingual
nerve and artery in this part of their course.

Branches.—Having given a few inconsi-
derable twigs to the middle constrictor, stylo-
glossus, digastric, and Zt Bie hae muscles,
and to the sublingual gland, &c.; the lingual

486

artery sends off the following branches. a,
The hyoidean branch, arising at the external
edge of the hyoglossus muscle, passes be-
tween the genio-hyoideus and genio-glossus,
and coming forward in the mesial line, de-
scends over the front of the body of the os
hyoides, and anastomoses with the hyoidean
branch of the thyroid artery, giving branches
to the muscles, in the vicinity of which it
passes and to the integuments. 6, The dorsalis
lingue, arising under cover of the hyoglossus,
passes upwards and outwards, crossing the
stylo-glossus and distributes its branches over
the posterior part of the dorsum of the tongue,
the tonsils, velum palati, and epiglottis, where
it anastomoses with the laryngeal branch of
the superior thyroid. At the internal edge
of the hyoglossus the lingual artery divides
into the sublingual and ranine. c, The sub-
lingual branch passes forwards between the
mylo-hyoid and genio-glossus muscles and
above the sublingual gland, to which it is
principally distributed, as well as to the
muscles of the tongue and the mucous mem-
brane of the mouth. Occasionally we find
the place of the sublingual artery supplied by
the submental, a branch of the facial. d, The
ranine artery, which is the continuation of the
trunk of the lingual, passes forward between the
genio-glossus and lingualis, and running along
the under surface of the tongue by the side
of the attachment of the frenum, sends nu-
merous branches into the substance of that
organ, and ends by anastomosing with the
ranine of the opposite side. It is this artery
which is endangered if the scissors be directed
too much upwards in dividing the frenum
lingue in children.

3. The labial artery, called also facial or
external maxillary, (a. facialis v. mazillaris
externa, ) varies very much in its origin, size,
and the extent of its distribution. It is usually
the largest of the three anterior branches of
the external carotid, and supplies the whole
of the anterior part of the face; sometimes,
however, it only extends as far as the angle
of the mouth, beyond which its place is
supplied by the temporal artery. There is,
perhaps, no other artery which presents so
many varieties, even on opposite sides of the
body in the same subject. From its origin
it proceeds, in a tortuous course, inwards
and forwards, towards the internal part of the
angle of the lower jaw, covered by the hypo-
glossal nerve, the digastric and stylo-hyoid
muscles: it then passes between the lower
jaw and submaxillary gland, lodged in a
groove in that gland; after which it turns
over the inferior border of the lower jaw, and
arrives on the external surface of that bone
a little in front of the anterior edge of the
masseter muscle: from this it ascends tor-
tuously towards the commissure of the lips,
covered by the skin and the platysma; thence
passing upwards and inwards under the zygo-
matic muscles, and over the buccinator and
levator anguli oris, it continues to ascend in
the groove between the cheek and the upper
lip and by the side of the nose, to the internal

CAROTID ARTERY.

canthus of the eye, where, very much dimi-
nished in size, it terminates by anastomosing
with the nasal branch of the ophthalmic artery. _
Branches.— The branches of the labial artery
are very numerous. a, The inferior palatine, _

of the carotid itself, it passes upwards between
the stylo-pharyngeus and stylo-glossus, to
which it gives branches: it then attaches itself
to the superior and lateral part of the pharynx,
supplying this region, the tongue, and the
tonsil. Having reached the velum palati, it
divides into many branches, which are dis-
tributed to the muscles, mucous membrane,
and glands of that organ, and to the Eustachian
tube. These branches anastomose with the
superior palatine branch of the internal max-
illary. The tonsillitic artery, (arteria tonsil-
laris of Soemmerring,) enumerated as a dis-
tinct branch of the labial by Professor Harrison,
is, more properly speaking, a branch of the
inferior palatine.

In passing through the sub-maxillary gland,
the labial artery gives off several branches to
this gland, the internal pterygoid muscle,
and the mucous membrane of the mouth: as
it is about to turn over the side of the lower
jaw, there arises from it a branch of more
considerable size, namely, b, the submental
branch. This artery passes forwards beneath
the base of the lower jaw, covered by the
platysma and anterior belly of the digastric,
between which and the mylo-hyoideus it takes 7
its course towards the symphysis of the chin,
distributing branches to supply the muscles
and integuments in this region and to anasto-
mose with the sublingual ; some of its branches
mount over the chin and communicate with
the arteries of the lower lip: the submental
artery sometimes furnishes the sublingual, and
at other times it is given off by this latter.

From the inferior border of the lower jaw
to the commissure of the lips, the labial gives
several branches, some of which are anterior
and some posterior: the posterior are com-
paratively insignificant branches distributed to
the masseter, platysma, buccinator, parotid
gland and duct, the cellular tissue and in-
teguments of the cheek, which communicate
with branches of the transverse facial. Besides
smaller branches given off anteriorly to the
lips, there are two considerable branches and
one of lesser size, which require a more par-
ticular description ; viz. c, the inferior labial ~
coronary arises about midway between the —
commissure of the lips and the base of the —
lower jaw, it passes under the triangularis oris”
muscle, to which, as well as to the quadratus, —
levator labii inferioris, and mucous membrane
of the mouth, it gives numerous branches and
anastomoses with its congener, and the mental
branch of the inferior dental. This artery i:
sometimes smaller on one side than on ft
other; it is sometimes absent on one s
when its place is supplied by the arter
the opposite side; sometimes it arises from —
the superior labial coronary; sometimes it is —
double. After having given off this branch,

7
.
i

CAROTID ARTERY.

the facial artery continues its course upwards
and inwards, and, opposite the commissure
of the lips, gives off d, the superior labial
coronary artery. This vessel passes inwards
among the fibres of the orbicularis oris, runs
above the free border of the upper lip nearer
to its mucous membrane than to its cutaneous
surface, gives branches to the various parts
composing the upper lip, and meets the co-
ronary of the opposite side, with which it
very freely anastomoses. The superior labial
coronary always sends off from the place
where it anastomoses with that of the opposite
side a branch, which ascends towards the
septum of the nose, and which is called the
artery of the septum of the nose, (arteria
septi nasi.) The place of this artery is some-
times occupied by two or more branches; it
divides, near the septum of the nose, into
at least two branches, which pass, one on either
side, along the inferior border of the septum
to the extremity of the nose, where it anasto-
moses with branches of the lateral nasal :
sometimes the superior coronary gives off a
branch (ramus pinnalis), as it passes the ala
of the nose, to which, and the external part
of the nostril, it is distributed.

After the origin of the superior labial the
facial artery is reduced to a very small size,
and its continuation is by some called the
external nasal, arteria nasalis externa com-
munis. It continues to pass obliquely up-
wards, forwards, and inwards under the levator
labii superioris, to which it gives branches:
after anastomosing with the infra-orbital artery
and giving off branches, which pass forward
on the lateral surface of the nose, namely, e,
laterales nasi, and_f, dorsales nasi, which freely
anastomose with each other, with the artery of
the septum, and those of the opposite side
on the dorsum of the nose, it emerges from
between the two heads of the levator labii
superioris, and becoming subcutaneous, ter-
minates at the inner canthus of the eye by
anastomosing with the termination of the nasal
branch of the ophthalmic, at which place it has
received the name of the angular artery.

Irregularities of the labial or fucial artery.
It sometimes happens that the facial artery is
smaller than usual, and terminates at the angle
of the mouth or even below the situation of
the usual origin of the inferior coronary; in
this case the transverse facial branch of the
temporal generally fnrnishes the branches which
the coronary has failed to produce; on the
other hand the labial artery is sometimes of a
larger size than usual, as happens when it
furnishes supernumerary branches, such as the
ranine or sublingual. The facial artery is the
principal source of communication between the
superficial and deep branches of the external
carotid by its anastomoses with the infra-orbital,
nasal and dental arteries; and of the external
carotid with the internal, by its anastomoses
with the ophthalmic.

Internal branch of the external carotid,
Inferior pharyngeal artery, (a. pharyngea in-
Ferior v. ascendens, ) arises commonly from the
internal side of the external carotid ¢lose to its

487

origin, sometimes from the bifurcation of the
primitive carotid, more rarely from the internal
carotid, and occasionally from the occipital ;
sometimes its place is supplied by the inferior
palatine or by branches from the trunk of the
facial; sometimes it is double, in which case
only one of its branches arises from the external
carotid, the other being furnished by one of
the smaller arteries already mentioned, or by
the internal carotid; this artery is always the
smallest branch of the external carotid; it
passes perpendicularly upwards internal to the
externa! carotid between the trunk of that
vessel and the pharynx, lying on the rectus
capitis anticus major muscle, and closely re-
lated to the superior cervical ganglion of the
sympathetic. Having furnished branches from
its inner side, both ascending and descending,
to the constrictors of the pharynx and other
muscles, which also supply the mucous mem-
brane, and from its external side to the deep
muscles of the neck, it terminates at the basis
cranii, near the petrous portion of the temporal
bone, by giving off its terminal branches, of
which one, the proper pharyngeal, is princi-
pally distributed to the parietes of the pharynx,
and communicates by anastomosis with the
inferior palatine from the superior thyroid; a
second, the posterior meningeal artery, enters
the cranium by the foramen lacerum posterius,
or by an opening in the vicinity of the condyle
of the occipital bone, and is distributed to the
dura mater lining the inferior occipital fossa :
and a third ascends to the basis cranii, and per-
forates the cartilaginous lamella, which fills up
the foramen lacerum posterius, to enter the
cranium and be distributed to the dura mater.
PosTERIOR BRANCHES OF THE EXTERNAL
cAROTID.—1st. The occipital artery (a. occi-
pitalis) arises from the posterior side of the
external carotid, opposite the lingual or the
facial ; it sometimes but rarely comes from the
internal carotid; it passes at first a little ob-
liquely backwards along the lower border of
the posterior belly of the digastric muscle
which overlaps it; it crosses over the ninth pair
of nerves which winds beneath it just at its
origin, the internal .carotid artery, internal
jugular vein, and spinal accessory nerve ; and
passing backwards between the transverse pro-
cess of the atlas and the mastoid process of
the temporal bone it is lodged in a groove in
this latter bone, which is internal to the inser-
tion of the posterior belly of the digastric ; it
crosses the outer border of the rectus capitis
lateralis muscle, and continuing its course
beneath the sterno-cleido-mastoid, trachelo-
mastoid, splenius capitis and trapezius, and
over the obliquus superior and complexus, it
ascends tortuously over the superior part of the
occipital bone, where it becomes cutaneous
and anastomoses with branches from the tem-
poral, posterior auris, and opposite occipital.
The first branches of the occipital are small,
and are distributed to the sterno-mastoid, di-
gastric, and stylo-hyoid muscles, and to the
lymphatic glands in the neighbourhood ; the
branches which enter the sterno-mastoid are
sometimes considerable, and anastomose freely

488
‘n the substance of that muscle with the branches
which it receives from the superior thyroid.
The sterno-mastoid muscle very frequently
receives a large branch at this part arising dis-
tinctly from the external carotid. This Professor
Harrison considers should be classed among
the regular branches of the external carotid,
and he has described it under the name of a.
sterno-mastoidea.*

While the occipital artery is covered by the
sterno-mastoid, trachelo-mastoid, and splenius,
it gives branches to these muscles, some of
which descending anastomose with branches of
the cervicalis profunda and the vertebral ;
those which ascend are distributed to the supe-
rior attachments of these muscles; amongst
them there is one branch occasionally found
which penetrates into the cranium by the mas-
toid hole, and is distributed to the dura mater,
under the name of posterior meningeal of the
occipital.

When the occipital artery comes out from
beneath the splenius muscle it divides into
those branches which are distributed over the
posterior surface of the occipital bone, sup-
plying the occipito-frontalis and the scalp, to-
gether with the pericranium, and anastomosing,
as already mentioned, with the opposite occi-
pital, posterior auris, and temporal. One of
these branches frequently enters the cranium
by the parietal hole, and spreads over the dura
mater.

The occipital artery sometimes gives small
twigs, which enter the cranium by the foramen
lacerum posterius and the anterior condyloid
foramen.

2d. A. posterior auris, v. auricularis pos-
terior, arises immediately after the occipital,
in the substance of the parotid gland; it is
generally a much smaller vessel than the latter,
from which it is mostly separated by the stylo-
hyoid muscle: sometimes it comes from the
occipital. It passes upwards and backwards
under the parotid gland between the mastoid
process of the temporal bone and the cartila-
ginous tube of the ear; it first sends branches
to the parotid gland, the stylo-hyoid muscle,
the posterior belly of the digastric and the
external ear; it then gives off the stylo-
mastoid artery, which, among other branches
to the external ear, gives off one to be dis-
tributed to the membrana tympani. Then
the stylo-mastoid traversing the aqueduct
of Fallopius finds its way into the cavity of
the tympanum, on the lining membrane of
which, and its prolongation into the mastoid
cells, its branches are expended, where it anas-
tomoses with a branch of the middle menin-
geal, which enters the hiatus Fallopii, and
arrives in the hae cpg along with the chorda
tympani nerve. Sometimes the stylo-mastoid
artery comes from the middle meningeal.

When the posterior auris gets to the front of
the mastoid process it divides into two branches,
one of which is anterior and the other pos-
terior; the former spreads its branches over all

* Surgical Anatomy of the Arteries of the Human
Body, vol. i.

CAROTID ARTERY.

arts of the internal surface of the ear
atter ascends in front of the mastoic
rior auris

and occipital arteries.* .
While traversing the parotid gland the ex- —
ternal carotid gives several small branches to
the masseter and pterygoid muscles, to the
substance of the gland itself, and a few to the
front of the external ear; occasionally it gives
origin to the transversalis faciei in this course.

Behind the neck of the condyle of the lower
jaw the external carotid divides into its two
superior and terminal branches, the temporal
and internal maxillary.

1. Temporal artery, (a. temporalis.) The
temporal artery ascends at first a little obliquely
outwards between the ramus of the jaw and
the tube of the ear, covered by the parotid
gland ; crossing the zygoma at its posterior
part, and passing under the anterior auris
muscle, it mounts up over the temporal apo-
neurosis, and becomes subcutaneous for the
remainder of its course.

Immediately after its origin the temporal
gives off anteriorly a very considerable
branch, which is called the ¢ransversalis Juciei :
this artery sometimes arises from the trunk of
the external carotid ; it passes forward over the
neck of the condyle of the lower jaw, and,
crossing the masseter muscle, runs superior to
the duct of Steno, which it accompanies across
the face; it anastomoses with the labial, buccal,
and infra-orbital arteries. The branches which
the transversalis faciei usually gives off are
distributed to the parotid gland and its duct,
the masseter, zygomatic, and orbicularis pal-
pebratum muscles, and the integuments. I
have seen an instance in which this artery arose
from the external carotid opposite the angle of
the jaw, beneath which it passed forwards, and
joined the labial at the anterior edge of the
masseter muscle.

When the temporal artery has arrived at the
zygoma, it gives a branch called middle tem-
poral, which pierces the temporal aponeurosis,
and ascends in the substance of the temporal
muscle, to which it is distributed, and which
anastomoses with the deep temporal arteries.

Having given off a few small branches to
the parotid gland, integuments, and external
ear, the temporal artery ascends on the temporal —
aponeurosis, and divides into two branches, ~
the anterior and posterior. The anterior branch —
ascends in a serpentine course towards the
forehead, and sends off many branches, which
are distributed to the occipito-frontalis, the
orbicularis palpebrarum, and integuments, and
which anastomose with the superciliary and

* [The surgical anatomist cannot fail to no
the relation of the posterior auris artery to the
dura nerve, as it lies superficial to and nea
mastoid process than that nerve, so as to be ¢
derably, although not necessarily, enda
the operator proceeds to divide the n
emergence from the stylo-mastoid foramen.

CAROTID ARTERY.

frontal branches of the ophthalmic and with
the opposite temporal. The posterior branch
passes upwards and backwards in a tortuous
course, and supplies the integuments, tem-
poral aponeurosis, pericranium, &c. These
branches anastomose with the anterior branch,
with the opposite temporal, the occipital, and
posterior auris.
_ 2. The internal mazillary artery, (a. maxil-
laris interna, ) is larger than the preceding; im-
mediately after its origin it passes downwards
and inwards under the neck of the condyle of
- the lower jaw; it then mounts forwards and in-
wards between the temporal and external ptery-
goid muscles, and usually passing between the
two origins of the latter, it enters the pterygo-
maxillary fossa, where it ascends as high as
the level of the inferior wall of the orbit, oppo-
site which it takes a horizontal direction. At
this place it divides into numerous branches,
which are distributed on one side inwards to-
wards the nose, and on the other side to the
external part of the face.

The branches of the internal maxillary are,
a. the middle meningeal, b. the inferior dental,
c. the posterior deep temporal, d. the masseteric,
e. pterygoid branches, f. the buccal, g. the an-
terior deep temporal, h. the alveolur, i. the
infra-orbital, 1. the superior palatine, m. the
vidian, n. the pterygo-palatine, and o. the
spheno-palatine: in addition to these the in-
ternal maxillary artery gives several branches to
the cellular tissue and other parts surrounding it.

a. Lhe middle meningeal artery (a.meningea
media, spinosa ) arises from the superior part of
the artery and passes directly upwards on the
inside of the external pterygoid muscle, to
which, to the superior constrictor of the pharynx
and muscles of the velum palati it sends
branches, and passing between the tensor
palati muscle and internal lateral ligament of
the temporo-maxillary articulation, enters the
cranium through the foramen spinale of the
sphenoid bone, and immediately gives off some
small branches, which pass through the hiatus
Fallopii to the cavity of the tympanum, where
they anastomose with the stylo-mastoid artery ;
other branches pass forwards towards the orbit
into which some of them occasionally enter by
the foramen lacerum. The meningeal artery
then divides into two branches, an anterior and
a posterior; the anterior, which is the larger,
might be considered as the continued trunk; it
mounts forwards towards the anterior inferior
angle of the — bone, where it is lodged in
a groove, and sometimes in a canal in the sub-
stance of that bone. This branch at first gives
twigs to the foramen lacerum, which anastomose
with the lachrymal ; after which it mounts on
the parietal bone, principally following the
course of the coronal suture, sending its bran-
ches upwards and backwards between the dura
mater and the inner surface of the parietal
bone. ‘The posterior branch passes backwards
in a curved direction on the inner surface of the
Squamous portion of the temporal bone, and
advancing towards the inferior border of the
a bone, is expended on the posterior and

teral part of the dura mater. The branches

489

of the middle meningeal artery spread over the
external surface of the dura mater, and occupy
the grooves which are disposed in an arbores-
cent form on the internal surface of the parietal
bone. The middle meningeal artery anasto-
moses with that of the opposite side and with
the other arteries of the dura mater.

b. The inferior maxillary or inferior dental
artery sometimes coming from the middle me-
ningeal, descends to the posterior dental hole
by which it enters the dental canal, passing be-
tween the inner surface of the ramus of the jaw
and the outer surfaces of the internal pterygoid
muscle and the internal lateral ligament of the
temporo-maxillary articulation, to which it gives
small twigs: before it enters the dental hole, it
gives off a small branch, which passing down-
wards and forwards in a groove on the inside
of the lower jaw, is distributed to the mylo-
hyoid muscle and mucous membrane of the
mouth. In the dental canal this artery passes
forwards beneath the alveoli of the molar teeth, -
sending upwards in its course several branches
which penetrate into the alveoli, and enter the
cavities of the teeth by the holes in their roots ;
having arrived opposite the mental hole, it
sends a branch which passes onwards beneath
the alveoli of the canine and incisor teeth, to
which it is distributed ; while the continuation
of the artery coming out through the mental
hole is distributed to the muscles of the lower
lip, where it anastomoses with the labial.

c. The posterior deep temporal artery arises
after the dental; it passes upwards between the
temporal and external pterygoid muscles, and
sinking into the substance of the former, divides
into a great number of branches, which spread
over the squamous portion of the temporal
bone, and are distributed to the temporal mus-
cle and pericranium. This artery anastomoses
with the anterior deep temporal, the middle,
and the superficial temporal.

d. The masseteric is a small branch often
arising from the posterior deep temporal; it
passes outwards between the posterior border
of the temporal muscle and the condyle of the
lower jaw, and enters the masseter muscle,
where it anastomoses with the transversalis
faciei.

e. The pterygoid arteries are irregular as to
number, size, and origin; they either come
from the trunk of the internal maxillary or the
posterior deep temporal, and are distributed to
the pterygoid muscles.

J. The buccal artery does not always arise
from the internal maxillary itself; it sometimes
comes from the anterior deep temporal, the
alveolar, or infra-orbital. It passes downwards
and forwards between the internal pterygoid
muscle and ramus of the lower jaw, and ad-
vances over the surface of the buccinator mus-
cle, to which it gives branches, as well as to the
zygomatic and other muscles of the lip: it
anastomoses with the labial, infra-orbital, and
transversalis faciei.

g- The anterior deep temporal arises from
the internal maxillary, near the outer wall of
the temporal fossa beneath the temporal mus-
cle, to which it is distributed ; some of its

490
branches enter the orbit through the malar
bone, and spread over the lachrymal gland,
communicating with the lachrymal artery.

h. The alveolar artery descends forwards
over the superior maxillary bone, very tortuous
in its course ; it gives two or three twigs, which
pass into the inferior and posterior dental fora-
mina to be distributed to the lining membrane
of the antrum maxillare and the molar teeth;
the other branches of the alveolar artery are
distributed to the gums, to the buccinator, to
the periosteum of the superior maxillary bone,
and to the cellular substance of the cheek:
they communicate with the infra-orbital, labial
and buccal.

t. The infra-orbital artery arises from the
internal maxillary at the superior part of the
pterygo-maxillary space; it enters the infra-
orbital canal, through which it passes forwards
and inwards, sending branches into the orbit
and maxillary sinus; passing out by the infra-
orbital hole it comes forward on the face
behind the levator labii superioris, and termi-
nates ina number of branches, which pass into
the muscles of the upper lip, and anastomose
with the labial, alveolar, buccal, and nasal
branch of the ophthalmic.

The remaining branches of the internal max-
illary are given off in the pterygo-maxillary
space; of these the first is

l. The superior palatine descends behind
the tuberosity of the superior maxillary bone
in the palato-maxillary canal : it usually gives
off two branches, which descend through holes
in the pterygoid process of the* palate bone,
and are distributed to the soft palate; while
the trunk of the superior palatine passing out
of the posterior palatine hole, directs itself for-
wards and inwards in a groove on the surface
of the hard palate, and divides into numerous
branches, which are distributed to the mucous
membrane and glands of the palate, to the
gums, and to the superior maxillary bone; one
of these branches sometimes passes up through
the foramen incisivum to the nasal fossz.

m. The vidian artery is an insignificant
branch which traverses the vidian canal from
before backwards, and coming out of its poste-
rior Opening is distributed to the Eustachian
tube and the roof of the pharynx: it anasto-
moses with the inferior pharyngeal.

nm. The pterygo-palatine or superior pha-
ryngeal is a small insignificant branch, which
passes through the pterygo-palatine hole, and
is distributed like the former to the roof of the
pharynx and Eustachian tube, sending some
branches to the sphenoid bone and the mem-
brane lining its sinuses.

0. The spheno-palatine artery may be con-
sidered the termination of the internal maxil-
lary ; it enters by the spheno-palatine hole into
the posterior part of the nasal fosse, and divides
into two principal branches ; an external and
an internal; the internal branch passing across
the roof of the nasal fossz arrives at the septum,
on which its branches are principally distri-
buted ; it also supplies branches to the roof of
the pharynx and the posterior ethmoidal cells;
the external branch descends on the lateral wall

CAROTID ARTERY.

of the nose, sending its branches over the
spongy bones and into the antrum maxillare ;
dhiewe ranches anastomose with the ethmoidal
branches of the ophthalmic artery. ian

THE INTERNAL CAROTID ARTERY, (carotis in-
terna seu cerebralis, Semm. cérébrale antérieure,
Chaussier.) This artery is larger than the external
carotid inthe foetus, but in the adultis only equal
in size to that vessel, aud sometimes even smaller.
At its origin it takes a curve outwards so as to
get external to the commencement of the ex-
ternal carotid; it then mounts upwards and
forwards in front of the three superior cervical
vertebra, and making a few contortions along
the side of the pharynx, enters the foramen
caroticum of the temporal bone, traversing the
carotid canal of that bone internal to the ca-
vernous sinus, perforates the dura mater internal
to the anterior clinoid process of the sphenoid
bone, where it divides into two large branches,
the anterior and middle cerebral.

The internal carotid artery has the following
relations from its origin to the place where it
enters the foramen caroticum: anteriorly it has
the external carotid and its branches in contact
with it at its origin, also the hypoglossal or lin-
gual nerve, and as it passes under the digastric
muscle it also slips beneath the following parts
which lie between it and the external carotid,
the styloid process, with the muscles attached
to it, part of the parotid gland, the glosso-
pharyngeal and inferior pharyngeal nerves.

Posteriorly it lies on the rectus capitis anti-
cus major, having the par vagum and superior
laryngeal nerve behind it, and higher up the
trunk of the hypo-glossal nerve coming from
between it and the internal jugular vein.

The internal jugular vein bounds it externally
at first, but passes to its posterior side above
where it gets to the internal side of the root of
the styloid process. Internally the carotid ar-
tery lies on the side of the pharynx to which it
is more closely applied towards its upper part,
lying on the stylo-glossus and the outer surface
of the superior constrictor muscles, which with
some cellular membrane and a venous plexus
separate it from the tonsil, external and poste-
rior to which it lies, at the distance of from six
to eight lines in the natural state of the parts;
but when that gland is enlarged in consequence
either of acute inflammation or chronic disease,
the distance between it and the artery is dimi-
nished so much as to expose the latter to some
risk of being wounded in opening abscesses in
the tonsil, an occurrence of which the records
of experience are not without examples. In
this stage of its course the internal carotid
seldom gives any branches; occasionally, how-
ever, the inferior pharyngeal or the occipital
arises from it. Having entered the carotid —
canal, the artery ascends vertically, then turns
forwards and inwards, and passing out of the —
canal opposite the posterior clinoid process, it
takes a second turn upwards, then forwards —
along the side of the sella turcica, between the
layers of the dura mater which include the ca-
vernous sinus, between which latter and the
bone the artery is situate. At the anterior
extremity of the side of the sella turcica it makes _

CAROTID ARTERY.

“rotic: on reaching the margin of the orbit, it

a third turn upwards under the anterior clinoid
process, and passing backwards and a little in-
wards it perforates the dura mater between the in-
ternal side of this process and the commissure of
the optic nerves. The only vessels which it gives
from its entrance into the foramen caroticum to
the place where it perforates the dura mater are
one or two small branches which perforate the
petrous portion of the temporal bone, and pass
to the cavity of the tympanum, and as it lies
beside the cavernous sinus, two or three little
twigs to the dura mater, pituitary gland, body
of the sphenoid bone, and to the third, fourth,
fifth, and sixth pairs of nerves which lie ex-
ternal to it and in contact with the outer or
inner wall of the cavernous sinus.

The ophthalmic artery arises from the an-
terior side of the carotid while that vessel is
passing into the dura mater, by the side of the
anterior clinoid process; it enters the foramen
Opticum at first external and inferior to the
optic nerve, over which it mounts obliquely
towards its internal side, passing between it and
the superior rectus muscle of the eye; it then
directs its course along the superior and internal
part of the orbit between the obliquus superior
and rectus internus, towards the inner canthus
of the eye where it terminates. Before entering
the orbit it gives off a few small twigs to the
dura mater and cavernous sinus, and within
the orbit it furnishes the following branches :—
1. the lachrymal; 2. the arteria centralis
retine; 3. the supra-orbital; 4. the ciliary; 5.
the muscular; 6. the ethmoidal; 7. the palpe-
bral; 8. the frontal; and 9. the nasal.

The order in which these arteries arise from
the ophthalmic presents many varieties; but
they are constant in their distribution.

1. The lachrymal artery is one of the largest
branches of the ophthalmic : it sometimes comes
from the middle meningeal, and enters the
orbit by the foramen lacerum orbitale of the sphe-
noid bone. It runs forwards between the ex-
ternal wall of the orbit and the rectus externus,
giving branches to that muscle, the periosteum,
levator palpebre superioris and sheath of the
optie nerve. One of its branches traverses the
malar bone, and entering the temporal fossa
anastomoses with the anterior deep temporal ;
another little branch frequently traversing this
bone Sa outwards through the same hole
with the nervus subcutaneus male, and anas-
tomoses with branches of the transversalis faciei.
The continuation of the artery then divides into
several branches which are distributed to the
lachrymal gland and the external part of the
upper eyelid, anastomosing with the palpebral
and the temporal arteries.

2. The central artery of the retina (arteria
centralis retiné,) penetrates the substance of
the optic nerve to enter a canal in its centre,
the porus opticus, in which it passes forwards,
and is distributed to the retina, the vascular
layer of which it forms by its ramifications.

3. The supra-orbital arises after the centralis
retinz, passes forwards along the superior wall
of the orbit above the levator palpebre supe-

rioris and superior rectus, giving branches to

these muscles, the periosteum, and the scle-

491

passes out through the superciliary foramen,
along with the frontal branch of the ophthalmic
nerve, giving in its passage a branch which
enters the substance of the frontal bone; this
artery then mounts beneath the corrugator su-
percilii and orbicularis palpebrarum muscles,
and is expended on these muscles, the occipito-
frontalis and the integuments; it anastomoses
with branches of the lachrymal and frontal.

4. The ciliary arteries sometimes amount in
number to thirty or forty; they consist of three
sets: the posterior or short, the long, and the
anterior. The posterior ciliary arteries are very
numerous, sometimes amounting in number to
thirty or forty: although mostly arising from
the ophthalmic, some of them come from the
inferior muscular, the supra-orbital, posterior
ethmoidal or lachrymal; they run along the
optic nerve very tortuous, and entangled with
the ciliary nerves, anastomosing freely with
each other.

The posterior or short ciliary arteries pierce
the sclerotic close to the entrance of the optic
nerve; some of their branches are distributed
to that membrane in which they anastomose
with branches from the muscular arteries;
while all the others advance nearly parallel,
dividing at very acute angles into numerous
smaller twigs; these branches are at first ex-
ternal to the choroid ; but in their course for-
wards they penetrate to the internal surface of
that membrane, and becoming more numerous
from having undergone new subdivisions, form
a network of anastomoses from which several
branches are sent to the ciliary margin of the
iris, where they anastomose with the anterior
ciliary, but.a greater number are given to the
ciliary processes in the centre of which they
form a very fine network, and finally end in a
circle of anastomoses surrounding the margin
of the circle in which these processes terminate
internally.

The long ciliary arteries are two in number,
one internal, the other external ; they are larger
than the short ciliary arteries among which they
arise, but pierce the sclerotic obliquely at a
greater distance from the optic nerve; they
pass forwards between the sclerotic and cho-
roid, and having arrived at the ciliary ligament,
they divide each into two long branches which
separate from each other at obtuse angles, and,
coursing along the ciliary margin of the iris,
form a circle around the greater circumference
of that membrane which receives branches of
anastomosis from the short ciliary arteries.
From the interior of this circle numerous
branches arise, each of which divides into two,
which diverge at obtuse angles, and, anastomo-
sing with each other and with the anterior
ciliary, form another arterial circle within the
former. Thus there are two arterial circles, one
within the other at the greater circumference of
the iris. From the concavity of this inner
circle the arteries of the iris arise. These arte-
ries are very numerous; they converge in ser-
pentine lines towards the papillary margin of
the iris, where they anastomose, in the manner
of the mesenteric arteries, to form the lesser

492 CAROTID ARTERY.

arterial circle of the iris. All these arteries,
however, do not contribute to form this lesser
arterial circle ; a great number pass beyond it,
-and, along with the branches which arise from
its concavity, advance towards the pupil. There
are thus three arterial circles in the iris, two
close together at its greater circumference or
te margin; the third much smaller, sur-
rounding its pupillary margin, and commu-
nicating with the preceding by a radiation of
branches situated on the anterior surface of the
iris.

The anterior ciliary arteries are two or three
in number; sometimes coming from the palpe-
bral or from the branches which go to the recti
muscles ; they pass forward to the anterior part
of the globe of the eye, where they each di-
vide into many branches, the smaller of which
are distributed to the conjunctiva and the scle-
rotica, the others pierce the sclerotica, near the
circumference of the cornea, pass through the
ciliary ligament, and join the arterial circles of
the greater circumference of the iris; some
passing beyond that circle go to the iris, and
others are distributed to the anterior part of the
choroid.

5. The muscular arteries generally consist of
two, an inferior and a superior. The inferior
muscular artery is a branch which is generally
present; it sometimes gives off the centralis
retin and one or more ciliary; it passes in-
wards to supply the inferior and internal recti
muscles, and sends some branches into the
nasal fossz.

The superior muscular is less regular than
the former; it passes forwards im mediately
under the superior wall of the orbit, and di-
vides into many branches, which are distributed
to the superior and internal recti, the superior
oblique, the levator palpebre superioris, the
periosteum, and the sclerotic.

6. The posterior ethmoidal artery sometimes
arises from the lachrymal or supra-orbital ; it
passes inwards between the superior oblique
and rectus internus, and enters the foramen
orbitarium internum posterius, giving branches
to the anterior ethmoidal cells and their lining
membrane ; it then enters the cranium, where
it is distributed to the dura mater, over the
cribriform plate, through the holes of which it
sends some branches to the pituitary mem-
brane, and anastomoses with the anterior
ethmoidal.

The anterior ethmoidal artery is given off
by the ophthalmic towards the anterior part of
the orbit; it passes through the foramen orbi-
tarium internum anterius with the nasal branch
of the ophthalmic nerve, and after giving
branches to the interior of the frontal sinus and
anterior ethmoidal cells, it enters the cranium
and divides into many branches, some of which
go to the dura mater, and others descend into
the nasal fosse by the holes in the cribriform
plate of the ethmoid bone, and are distributed
to the pituitary membrane.

7. The palpebral arteries sometimes arise by
a common trunk and sometimes separately.

The superior palpebral arises a little further
forward than the inferior; they are distributed

to the conjunctiva and to the eyelids, in whic

they spread out their branches between the
skin and the orbicularis muscle. They princi-
pally divide each into two branches, one of
which runs along the tarsal margin, supplying
the tarsal cartilage, Meibomian glands, and con-
junctiva, and the other nearer to the base of
the eyelids in an oblique course from within
outwards. .

The superior palpebral anastomoses with
the lachrymal, superciliary, frontal, and an-
terior branch of the temporal.

The inferior palpebral anastomoses with the
infra-orbital, the lachrymal, and nasal.

After the ophthalmic artery has given off
the palpebral, it divides into two branches, one
of which is the frontal and the other the nasal.

8. The frontal artery is usually the smaller
of the two; it passes out of the orbit at the
superior and internal part of the base of that
cavity, and divides almost immediately into
two or three branches, which ascend on the
forehead, over which they ramify, and are dis-
tributed to the orbicularis, corrugator super-
cilii, pyramidalis nasi, and occipito-frontalis
muscles, to the periosteum and common inte-
guments: these anastomose with the opposite
artery, the superciliary, and the temporal.

9. The nasal artery varies in size, being
sometimes only a very trifling branch, which
terminates at the root of the nose; sometimes
its size is considerable, as, when it descends
very low, contributing with the lateral nasal
branch of the facial to supply the place of the
dorsal artery of the nose, in which case it ex-
tends to the lower part of that organ; it always
anastomoses with the facial and inferior pal-
pebral, and gives branches to the integuments,
cartilages, and bones of the nose, to the la-
chrymal sac, to the corrugator supercilii, and
the internal part of the orbicularis palpebrarum.

The internal carotid, after it has furnished
the ophthalmic artery, is distributed entirely to
the brain, especially to its anterior part, the
posterior part of that organ receiving its prin-
cipal supply of blood from the vertebral.
Having pierced the dura mater at the external
side of the anterior clinoid process, and ex-
ternal to the optic nerve, the internal carotid
artery gives several minute branches to this
nerve, to the pituitary gland, the infundibulum,
and anterior part of the brain; shortly after
this it gives a branch which is very variable in
size, frequently differing in this respect on
opposite sides in the same subject; this is the
lateral or posterior communicating branch of
Willis, which passes backwards and a little
inwards, external to the commissure of the
optic nerves, infundibulum, tuber cinereum,
and the corpora mammullaria, and joins the

posterior artery of the cerebrum, which is a |

branch of the basilar: the motor oculi lies ex-
ternal to it.

plexus.

After having given off the communicating =
artery, the carotid sends a branch to thechoroid
plexus, the arteria choroidea ; the artery passes

In its course it gives small
branches to the corpora mammillaria, the crus
cerebri, the optic nerves, and the choroid

Ast

CAROTID ARTERY. 493

backwards and outwards, enters the tractus
opticus, supplies the en mater of the middle
lobe of the brain and the optic thalamus, and,
entering the inferior cornu of the lateral ven-
tricle, spreads out its branches in the choroid
plexus.

After having given off the choroid artery, the
internal carotid divides always at an obtuse
angle, and at the internal extremity of the fis-
sure of Sylvius, into two branches, the an-
terior and the middle cerebral, of which the
latter is much the larger vessel: sometimes
the lateral communicating artery arises at the
eh of this division, and forms with these

ranches a sort of tripod.

The anterior cerebri, also called the artery
of the corpus callosum, is always smaller than
the media cerebri; it passes upwards, forwards,
and inwards to the fissure which separates the
anterior lobes of the cerebrum, passing over
the optic nerves, and inferior to the internal
origin of the olfactory: on entering the above-
mentioned fissure, it approaches closely to the
corresponding branch of the opposite side,
with which it communicates by a large and
very short transverse branch, ca'led the anterior
communicating artery, by which the circle of
Willis is completed anteriorly: sometimes
this branch is double, and occasionally we find
it partially double, in consequence of a forking
of one of its extremities; its place is sometimes
supplied by a fasciculus of small branches ; it
gives off, especially when it is unusually long,
a number of small twigs, which pass upwards
and backwards to the septum lucidum, fornix,
and corpus callosum.

From the place of this communication the
trunk of the anterior cerebri passes forwards
under the corpus callosum, giving off consi-
derable branches to the inferior and internal
part of the anterior lobe of the cerebrum; it
then turns round to the anterior extremity of
the corpus callosum, mounts up on the internal
surface of the hemisphere of the cerebrum,
and divides into many branches, the anterior
and superior of which supply the convolutions
on their internal surface, while the posterior
take a lower course along the upper sur-
face of the corpus callosum, at the posterior
extremity of which they take an ascending
direction. All these branches extend to the
superior surface of the cerebrum, and anasto-
mose with those of the media cerebri and the
posterior cerebri, which is furnished by the ver-
tebral.

Besides these large branches into which the
arteria callosa divides superiorly, it gives off
from its inferior and concave side a vast number
of smaller branches, which penetrate the corpus
callosum. ;

Sometimes, instead of being connected by
the communicating branch, the anterior cerebral
arteries of opposite sides unite, forming a single
trunk, which runs forward for some little dis-
tance, and then divides into a right and left
branch ; this junction is the more remarkable,
on account of its analogy to the union of the
two vertebral arter‘es in forming the single
trunk of the basilar on the median line.

The media cerebri, from its greater size com-
pared with the anterior branch, appears, as it
were, the continuation of the trunk of the
carotid ; it passes outwards and backwards, in ~
the fissure of Sylvius, and divides into two
branches, the subdivisions of both of which
are distributed over the pia mater of the anterior
and middle lobes of the brain, anastomosing
in front with the anterior cerebri, and behind
with the posterior cerebri from the basilar:
this artery at first gives branches at the base of
the brain to the pia mater on the crus cerebri ;
one of these, larger than the others, enters the
inferior cornu of the lateral ventricle, where it
is lost in the choroid plexus.

The anterior and middle cerebral arteries are
not always similarly disposed on opposite
sides ; it not unfrequently happens, as Haller
has remarked, that the two large trunks of the
middle cerebral arteries are given off by the
right carotid, and the two anterior from the
left carotid, while the three others come from
the right: considering these anomalies with
that of the union of the two cerebral already
mentioned, we here find a very remarkable
repetition of many of the varieties exhibited by
the mode in which the trunks that spring from
the arch of the aorta take their origin.

For the BIBLIOGRAPHY, see that of ANATOMY
(INTRODUCTION), and of ARTERY,

(J. Hart.)

The following observations are to be regarded
as supplemental to the preceding article.

There is no fact more worthy of the atten-
tion of the practical surgeon, as regards the
anatomical history of the carotid artery, than
the free anastomosis which exists between the
external and internal carotids of both sides at
nearly all the stages of their course. This is
especially the case with the external carotid
arteries which anastomose at numerous short
intervals from their origin to their termination,
where they likewise communicate with some
small ramifications of the internal carotids.
Nor is the communication between the internal
carotids less free, although it is less frequent :
this communication is formed within the cra-
nium at the anterior segment of the circle of
Willis. Moreover, by means of the posterior
communicating artery the internal carotid anas-
tomoses with the posterior cerebral, and there-
by with the subclavian, through the medium of
the vertebral artery. And farther, by the anas-
tomoses of the superior thyroid artery with the
inferior, and of the occipital with the cervicalis
ascendens, profunda, and vertebral, a commu-
nication is established between the external
carotid artery and the subclavian.

From the knowledge of the communication
thus existing between these several portions of
the arterial system of the neck and head, we
may deduce some very useful inferences.

1. It is evident that the carotids of both
sides may be injected by even a coarse injec-
tion, from a pipe introduced into the artery of
one side. This is a fact well known to every
practical anatomist.

494

2. With the knowledge of this freedom of
communication between the carotids, no sur-
geon will look for uniform success after the
application of a ligature, in cases of wounds
of either carotid or of one of its branches,
if the ligature be applied only below the situ-
ation of the wound. Nevertheless, experience
tells us, that such a plan of treatment has been
successful in several instances; and it is wor-
thy of notice that in almost all the successful
cases the primitive carotid was tied very shortly
after the infliction of the wound, at a time
when the collateral branches could not have
become sufficiently enlarged to admit of the
full circulation in them; while, on the other
hand, in two unsuccessful cases, the primitive
carotid was not tied for some days after the
receipt of the wound, and secondary hemor-
rhage ensued in each case.

3. The free anastomosis of the two internal
carotids with each other and with the sub-
clavians through the vertebrals within the cra-
nium, sufficiently evinces that the circulation
of the brain after the obliteration of either
carotid, by ligature or otherwise, may be easily
maintained ; and experience fully confirms this
inference from anatomy. That a disturbance
of the cerebral circulation does occur occa-
sionally after the operation of tying the carotid
is fully proved ; but it would appear that it is
an occurrence much more rare than might,
a priori, be expected. Of seventy cases, col-
lected by Berard,* in which this operation was
performed, symptoms arising from cerebral
affection appeared only im a very few, and in
two only of these instances the patients died
from the effect produced upon the cerebral cir-
culation. One of these cases occurred in the
practice of Mr. Aston Key; the patient fell
into a deep sleep after a severe fit of coughing,
and died shortly afterwards without awaking.
On examination it was found that the carotid
of the opposite side was obliterated by a co-
agulum nearly as low as its origin from the
aorta, so that the cerebral circulation could
only have been maintained by the two vertebral
arteries, which in this case were smaller than
usual. In the second case, which was ope-
rated on by Langenbeck,+ immediately after
the application of the ligature the patient be-
came motionless, with closed eyes, without
speaking, except when addressed several times
in succession ; he sank gradually, and died in.
thirty-four hours after the operation.t

In three of the cases collected by Berard,
some disturbance or indistinctness of vision,
on the same side as that on which the artery
was tied, followed the operation; in one of
these the impairment of sight was accompanied
by syncope, and a sensation of cold affecting

* Dict. de Médécine, art. Carotide.

+ Arch. Gén. de Méd. t. xix. p. 118.

¢ Dr. Mussey, of New Hampshire, in America,
has recorded a case in which he tied both primitive
carotids within twelve days of each other, and
without any untoward result. The reader will find
the case quoted at length in Mr. Guthrie’s valuable
hgh on the Diseases and Injuries of Arteries,
Pp. .

CAROTID ARTERY. ;

the whole of _ side ve the face; in a second,
related by Mr. Mayo, the impaired vision was
only on "he vate sed the carotid of which
side had been tied, and the sense was y
restored in a few hours. In the third case one
eye was completely ee of sight, and the
sense of hearing greatly weakened in the ear
of the same side. Berard remarks that the loss
gr impairment of vision on one side is un-
avourable to the opinion that such an occur-
rence is to be attributed to disturbed cerebral
circulation ; it is sufficiently accounted for by
the fact that there is a considerable diminution
in the quantity of blood sent to the eye; for
that organ is supplied by a direct branch of the
internal carotid, viz. the ophthalmic, which
anastomoses at its termination with several of
the terminal branches of the arteries of the
face ; and it is not improbable that in the cases
above referred to, the branches which form this
anastomosis, as well as those forming the circle
of Willis at the base of the brain, were much
smaller than usual.

In other cases hemiplegia, more or less ge-
neral and perfect, followed the operations after
a longer or shorter period. In a case related
by Magendie, that of a young girl, in whom
the deft carotid was tied, there appeared on the
sixth day paralysis of the right arm, of the
pharynx and larynx, and numbness of the right
lower extremity. The paralysis gradually di-
minished, but the intellect was so far impaired
that the patient lost the power of reading.*
In Sir A. Cooper’s first case, the right arm and
leg were deprived of sensation and in part of
motion on the seventh day after the operation ;
and a man, in whom Mr. Vincent tied the right
carotid for aneurism, was attacked with com-
plete hemiplegia of the left side in half an hour
after the operation, and continued in that state
till his death on the seventh day. It is re-
markable that, in all these cases, the paralysis
was situated on the side opposite to that on
which the artery was tied; a fact which alone
would indicate that the cause of the paralysis
was seated in the brain.

Aneurisms do not occur so frequently in the
carotid arteries as in the aorta or in the large
arteries of the extremities. They are most
frequently found situated at the bifurcation of
the common carotid, where also calcareous
and atheromatous deposits are very often met
with. In the lower part of the common ca~
rotid an aneurism is, of course, a more for-
midable disease than if it were situated high
up, in consequence of the impossibility of
applying a ligature between the artery and the
heart. Sometimes an aneurism of the aorta
projects upwards into the neck, compressing ©
and obliterating the carotid, and simulating all
the characters of aneurism of its lower portion.
I am not aware that there is on record any
instance of aneurism of the internal carotid
artery in its cervical portion, although our mu- _
seums are not without specimens of aneurismal —
dilatations of it after it has entered the cranium,
and as it lies by the side of the sella Turcica.

a
7
-

* Journal de Physiol, April, 1827.

CARTILAGE.

We sometimes find the cervical portion of this
artery in a tortuous state, but we rarely see in
it those atheromatous and earthy deposits which
are met with in other parts of it.

In the dead body there is no difficulty in
exposing the common carotid artery in any
part of its course, but during life much em-
barrassment is occasioned by the alternate di-
latation and collapse of the internal jugular
vein, corresponding with expiration and inspi-
ration, and sometimes by some small veins
which lie in front of the artery. It may be
cut down upon either above or below the omo-
hyoid muscle, but in the former situation the
superficial position of the vessel and the less
complexity of its relations render it more easy
to be got at. In both situations the anterior
margin of the sternomastoid muscle forms a
useful guide to the artery; but much more
careful dissection is required when the
operation is done in the region below the
omohyoid muscle. Here great care is de-
manded in dissecting back the sternomastoid
muscle, and in drawing the sternothyroid
inwards; the thyroid body and, on the left,
the csophagus must be avoided, and in pas-
sing the ligature round the artery, the ope-
rator must take care to avoid not only the vein
and par vagum but also the inferior thyroid
artery, the recurrent and sympathetic nerves
and the cardiac branches of the latter, and on
the left side the thoracic duct. As anomalies
in the distribution of some of the arteries in
the neck are occasionally met with, the surgeon
should be on his guard against such an occur-
rence, especially in operating in the low region
where they are most likely to be met with. Two
arteries may be found here occupying pretty
nearly the situation of the carotid artery. One
of these will be the carotid itself, the other the
vertebral, which sometimes passes high up in the
neck in front of the rectus capitus anticus muscle,
before it enters the canal in the transverse pro-
cesses of the cervical vertebre. In a case related
by Mr. Allan Burns,* the vertebral artery en-
tered this canal only a few lines below the bifur-
cation of the carotid, and in its passage up the
neck, parallel to and behind the carotid, it was
separated from that vessel only by its sheath.
A low bifurcation of the carotid artery would be
equally likely to occasion embarrassment; and
the possibility of such a condition of the cer-
vical vessels as well as of the anomalous course
of the vertebral artery before alluded to are
strong arguments in favour of the recommenda-
tion of Mr. Burns, that, “ when the surgeon
has.reached the sheath of the vessels he ought
uniformly, before opening it, to press the carotid
between the finger and thumb. If the pulsa-
tion of the tumour be not in this way con-
trolled, he will do well to pause before he pass
a ligature round that vessel.”+ In fine we
sometimes find the inferior thyroid artery cros-
sing in front of the common carotid in the
inferior region.

* Surgical Anatomy of the Head and Neck,
p- 170.
t Loc, cit.

495

It is very easy in the dead body to find the
primitive carotid low down in the neck by
cutting in the cellular interval between the
clavicular and sternal portions of the sterno-
mastoid muscle, but it is not so easy to pass
a ligature round it; and this difficulty is greatly
magnified in the living subject, in consequence
of the necessarily limited space in which the
operator has to work; the difficulty too is
greatly increased by the contractions of the
sternomastoid muscle.

To expose the external carotid artery shortl
after its origin, it is only requisite to follow the
same steps as are necessary for cutting down
on the common carotid above the omohyoid
muscle. It is in general advisable to apply
the ligature below the point at which the di-
gastric muscle crosses the artery and below the
origin of the superior thyroid. Some embar-
rassment is likely to result from the plexus
of veins which in this region often lies in front
and on the sides of the artery. A ligature,
however, may be passed round this artery
above the digastric muscle, but it will be re-
quisite that the external incision shall com-
mence higher up. The needle must be passed
between the parotid gland and the digastric
tendon, the distances between these parts hay-
ing been previously increased by drawing down
the tendon of the muscle.

(R. B. Todd.)

CARTILAGE (Lat. cartilago, quasi car-
nilago ; Gr. xovdgog; Fr. cartilage; Germ. Knor-
pel; Ital. cartilagine) is a firm elastic sub-
stance, of pearly whiteness, and uniform or
homogeneous in its appearance. It bears a
considerable analogy to bone, and is to be
found in situations where less rigidity and more
elasticity are required than the osseous system
presents.

Several tissues, differing a good deal from
each other, were formerly comprehended under
this term. These have been variously classified
by modern anatomists ; but the division of them
into cartilages and fibro-cartilages, proposed by
Bichat,* is that which is now generally adopted.
Although Bichat was happy in the choice of
names for these tissues, yet, in arranging the
individual pieces under the two heads just
mentioned, he has not been found quite correct.
Some of the true cartilages are placed by him
amongst the fibro-cartilages, an error which
Meckel perceived and rectified.

Cartilages may be divided into the temporary,
the permanent, and the accidental.

A. The Temporary cartilages are substitutes
for bone in the earlier periods of life, and after
a certain time become ossified. We find them
at birth forming the extremities and larger emi-
nences of long bones, a great part of the short
bones, and the margins of the broad ones.
These gradually disappear, and at puberty cease
to exist. It is unnecessary to say more of
them here. (See OstroGENy.)

B. Permanent cartilages are met with under

Par. 1812,

* Anatomie Générale, tom. iii.
Par. 1825.

+ Manuel d’Anatomie, tom. i.

496

two forms: 1, the articular, attached to bone,
and entering into the formation of joints; 2, the
por echo cna forming canals more or less per-
ectly.

I. The articular cartilages are called diar-
throdial, obducent, or of incrustation, when
they belong to the moveable articulations;
synarthrodial when connected with those very
limited in their motions, or the immoveable
articulations of some authors. We think it
unnecessary to do more than refer to these
cartilages here, as their characters will be found
fully described in the article ARTICULATION.

II. The non-articular cartilages are usually
much more flexible than the articular. In some
cases they are attached to bones, and lengthen
them out, as the preceding class. Of this we
see examples in the nose, the auditory canal,
and the Eustachian tube. In other cases they
are insulated, forming the basis of distinct
organs, as the larynx, the trachea, the eyelids.
All the cartilages of this class have a well-
marked perichondrium.* Some of them, as
the epiglottis, the tarsal cartilages, and those of
the alz nasi, are so thin, so flexible, and assume
so much of a fibrous appearance from their
perichondrium, that Bichat placed them amongst
the fibro-cartilages ; but these last never have
perichondrium, and their fibrous texture is
distinctly independent of their investment, as
is easily seen without any preparation. (See
FIBRO-CARTILAGE.)

The structure of non-articular cartilage, like
the other forms, may, by protracted maceration,
be shown to be fibrous; but the arrangement
of its fibres is different; they interlace a good
deal more.

The physical properties of cartilages are such
as to fit them admirably for the functions which
they have to perform. They are solid, resisting,
and incapable of extension, that they may be
able to preserve the form of certain parts as
effectually as bone; and they are flexible and
elastic, to enable them to yield in some degree,
and immediately to resume their original shape.

Elasticity is the property most essential to
them, and on this their usefulness mainly de-
pends. Its existence is easily demonstrated.
if the blade of a knife be pressed into a diar-
throdial cartilage, the reaction of the displaced
fibres expels it with force ; and a piece of any
cartilage, if bent between the fingers, returns
with a spring to its former shape. The elastic
fibres of diarthrodial cartilage are so placed as
to receive impressions on their extremities ;
they yield a little to force, and only a little,
else the ligaments would be too much relaxed ;
but they yield enough to let the opposite sur-
faces accommodate themselves to each other,
and to deaden the shocks which would other-
wise have an injurious effect on the nervous
centre. In fact, these articular cartilages serve
as a series of springs between the ground and
the delicate organs which they support. The

* If we except the capsule of the lens and the
posterior layer of the cornea, supposing these
structures to belong to the cartilaginous system.
See EYE.

CARTILAGE.

elasticity of the costal cartilages is obvious
essential. They are subject to torsion in
act of inspiration, and by their reaction bec
an important agent in expiration. “a
Differences depending upon age—Cartilages
are soft, transparent, and like jelly in the very
young foetus. Gradually, as the individual
advances to maturity, they become opaque,
white, firm, and elastic; and in the adult these
qualities are in their greatest perfection. In
old age they lose again their elasticity and
flexibility ; a yellowish colour takes the place of
their beautiful pearly white; they become dry
and brittle, and shew a great tendency to ossify.
Organization. — Cartilage appears at first |
sight to be perfectly homogeneous throughout,
like a concrete jelly, not shewing any traces of
organization, nor exhibiting the least appear-
ance of vessels. But, as an attentive examina-
tion proved it to be fibrous, so we shall be able
to satisfy ourselves that it possesses an organi-
zation similar to other parts of the living sys-
tem. In healthy cartilage, it is true, no red
vessels can be demonstrated, neither can the
finest injection be made to penetrate it, nor -
will madder used in food colour it. But dis-
ease sometimes shows red vessels ramifying
through its substance ;* and several other phe-
nomena lead us to the conviction that it is at
all times permeated with vessels, though they
may be too fine to admit the red globules. For
instance, we find cartilage assume a yellow
tinge in jaundice. If we slice off a bit, the dry
surface is soon moistened with a serous fluid,
which, doubtless, comes from its colourless
vessels. Exposed cartilages have been known
to granulate, which implies the existence of
vessels, and perhaps of cellular substance. And
we know that in the old and laborious there is
often not the least sign of wear, although the |
enamel of the teeth be quite worn away. Where /
a perichondrium is present, we may suppose |
the vessels first ramify in it before they enter
the cartilage. Dr. William Hunter describes
the arrangement of the vessels which supply ‘
diarthrodial cartilage to be very peculiar. He
says, “ All around the neck of the bone there
are a great number of arteries and veins which
ramify into smaller branches, and communicate
with one another by frequent anastomoses, like
those of the mesentery. This might be called
the circulus articuli vasculosus, the vascular
border of the joint. The small branches divide
into still smaller ones upon the adjoining sur-
face, in their progress towards the centre of the
cartilage. We are seldom able to trace them
into its substance, because they terminate ab-
ruptly at the edge of the cartilage, like the ~
vessels of the albuginea oculi when they come ~
to the cornea.”’+ ! i
It does not appear that nerves or absorbents _
have ever been traced into cartilages; but
phenomena of disease, pain, ulceration, &c., —
convince us that they are supplied with both.
Even in their healthy condition, though their

* Brodie on Diseases of Joints, p. 183, third
edition. ; Fat
+ Phil. Trans. 1743.

e

, od, ae ee
a) > «

CARTILAGE,

animal sensibility is exceedingly low, scarcely
perceptible, yet it probably does exist, and
will manifest itself whenever any cause is
operating upon them which might destroy their
texture. We may, indeed, cut an exposed car-
tilage without pain, and the violent pressure it
undergoes in a sound joint is unheeded. But
the former is a kind of injury from which car-
tilage may be said to be totally exempted, and
the latter is that for which it is peculiarly
adapted. In either case sensibility would be
useless or inconvenient. Let but a foreign body
however get into a joint, between its cartilages,
such as might disorganize them, and then an
alarm is set up too great to be attributed to the
synovial membrane alone, and depending, we
may suppose, “in part at least, on the cartilage
itself.

C. AcciDENTAL CARTILAGE.—By this name
we designate the cartilaginous concretions which
are occasionally found in situations where they
do not ordinarily exist. They present them-
selves in several organs, under various forms,
and in different stages of development. Laennec
divides them into perfect and imperfect ;* but
it is not easy to point out any line of distinction
between these two classes; they differ only in
degree, the one passing gradually into the other
as its development becomes more complete.
We rarely, indeed, meet with accidental car-
tilage which deserves to be called perfect ; in
one part it is fibrous, or of a dense cellular
nature, in another it is cartilaginous, while a
third portion of the same piece is passing into
the osseous state.

The forms and situations in which they
occur, will permit an arrangement of them
under three heads :—

1. The insulated or loose cartilages, which are
found either (a) in joints or (b) in serous sacs.

a. Those of the joints are rounded or ovoid,
usually flattened, sometimes lobulated, always
smooth, polished, and lubricated with synovia,
frequently osseous in their centre. They vary
in magnitude from the size of a mustard-seed
to that of an almond; and in one instance Mr.
S. Cooper found in the knee a concretion of
this kind, which was as large as the patella.
They also vary considerably in numbers ; Haller
saw twenty in the articulations of the lower
jaw, and Morgagni met with twenty-five in a
knee-joint. Their most usual seat is in the
knee, but they have been found in the hip,
jaw, elbow, and wrist. They are commonly
“loose,” moving freely in the cavity, but some-
times connected to the synovial sac by slender
membranous attachments.

With respect to the origin of these bodies
various opinions have been entertained. Haller

and Reimarus supposed that they were frag-

ments of the original cartilage, accidentally de-
tached. Cruveilhier found fifteen of them in a

___ hip-joint some years after it had been injured,
___ and conceived that he saw an exact correspon-
_ dence between them and certain depressions in

i
©

- y
tc

the cartilages of that articulation. Bichat con-
jectured they might be altered portions of the

* Dict. des Sciences Méd.
VOL. I.

497

synovial membrane. According to John I{unter,
they may have had their origin in a coagulum
of blood poured into the joint from an injured
vessel, and there becoming organized. This
coagulum would, he thought, assume, as in all
other situations, the peculiar organization of the
parts in its immediate vicinity. Laennec and
Beclard were of opinion that they might be
formed outside the synovial membrane, and
push it before them so as to form a pedicle,
which in some cases remained, but more gene-
rally was ruptured. This opinion Laennec sup-
ported by observations made on similar sub-
stances in serous sacs, where he traced them
through all the degrees of their development,
from the incipient stage, in which they formed
a slight projection behind the membrane, to the
ashi when they became perfectly isolated

odies. Sir Benjamin Brodie, whose authority
on this subject is of so much weight, remarks,
“Jt is generally supposed that these loose
bodies have their origin in coagulated lymph
which has been effused from inflammation of
the inner surface of the synovial membrane,
and which has afterwards become vascular. In
the majority of cases, however, which I have
met with, no symptoms of inflammation pre-
ceded their formation; and hence it is probable
that, in some instances, they are generated like
other tumours, in consequence of some morbid
action ofa different nature. They appear to be
Situated originally either on the external sur-
face, or in the substance, of the synovial mem-
brane; since, before they have become de-
tached, a thin layer of this latter may be traced
to be reflected over them.”*

When inflammation is of long standing in a
bursa mucosa, it is not unusual to find in it a
number of loose bodies, of a flattened oval
form, and of a light brown colour, with smooth
surfaces, resembling small melon-seeds in ap-
pearance. There seems to be no doubt that
these bodies bave had their origin in the coagu-
lated lymph effused in the early stage of the
disease.t From the resemblance which these
concretions bear to loose cartilages, we might
infer that they both have had a similar origin ;
but, as there can be no doubt that loose car-
tilages sometimes begin to be formed outside
the synovial membrane, we must not conclude
that this is the only mode.

From the evidence before us, therefore, and
from observations made on the second species
of accidental cartilage, to be mentioned by-and-
bye, we are inclined to admit two distinct
sources from which these loose cartilages may
have commenced. One, a deposit in the cel-
lular tissue outside the synovial membrane; the
other a deposit within this membrane. The ori-
gin of both being lymph, which becomes cartila-
ginous, and often proceeds to an osseous state.

b. Insulated cartilages are sometimes found
in connexion with true serous cavities. They
are seldom larger than a pea, rounded, floating,
or attached by a pedicle to the inside of the

* Pathological and Surgical Discases of the
Joints. Lond. 1834.
t Idem.
2K

498

sac, and, in some instances, distinctly outside
it. Laennec often found them between the
tunica vaginalis testis and the tunica albuginea,
and on one occasion in the lining membrane
of the lateral ventricles of the brain. Andral
saw three of these bodies in the serous mem-
brane of the brain; one of them floated loose
and unattached in the sac of the arachnoid ;
the other two were attached to the choroid
plexus by a delicate cellulo-vascular prolonga-
tion. He also often found them in the peri-
toneum, sometimes perfectly isolated, at other
times appended to the serous membrane.* _

2. Accidental cartilages of incrustation,
occurring in plates, are very irregular in size
and shape. They are most frequently found in
fibro-serous membranes, as the dura mater, the
pericardium, and the immediate coverings of
the testis and spleen. Upon this last viscus
they are seen more frequently than in any other
situation whatsoever. Bichat supposed they
were altered portions of the fibrous membrane,
having so generally met with them where the
latter existed. The subserous cellular tissue is
the proper seat of them. We often find them
between the middle and internal coats of ar-
teries, in what may likewise be called a sub-
serous cellular tissue. (See ArTERY.)

It is exceedingly rare to meet with them
under mucous membranes. Andral saw one
solitary instance of a true cartilaginous mass
developed in the submucous cellular tissue of
the stomach. The subcutaneous cellular sub-
stance is likewise nearly exempt from them ;
but the same experienced pathologist relates,
that one of the lower extremities of a woman
who died in La Charité in the year 1820, was
affected with elephantiasis ; underneath the
skin, and occupying the place of the muscles,
which were reduced to a few pale fibres, was
found an enormous mass of condensed hard
cellular tissue, possessing, in many places, all
the physical characters of cartilage. In all
these instances there is every reason to believe,
from the closest examination, that the newly
formed substance is developed at the expense
of the cellular tissue alone, and that neither
the fibrous nor the serous membranes are al-
tered, nor indeed any adjoining texture. These
last seem to be replaced by the accidental for-
mation, but they are only absorbed to make
room for it, and not transformed into the new
substance. An exception must, perhaps, be
made in favour of mucous membrane, which
appears capable of undergoing this change.
Laennec relates the case of a child, in the
membranous portion of whose urethra he
found a large calculus. The mucous mem-
brane of the part presented several patches, of
the size and thickness of a man’s nail, which
appeared to him semi-cartilaginous, and were
incorporated with, and formed part of, the
mucous membrane. In like manner Beclard
found the mucous membrane of the vagina, in
a case of prolapsus uteri, studded over with
cartilaginous spots ; and he observed a similar

* Andral’s Pathological Anatomy, translated by
Townsend and West.

CARTILAGE.

ap ce on the p

What is the cause of these formations ?

Most probably they have their commencement |

in some obscure inflammatory action. It is
true we often find them where there is no other
appreciable lesion whatsoever, nor any trace of
inflammation in the neighbourhood ; but, on
the other hand, they seem to be but a step re-
moved, in structure, from coagulable lymph,
and are sometimes imbedded in it; and the
irritation and consequent inflammation o~
duced by foreign bodies must be allowed to
have occasioned them in the instances just
related from Bichat and Beclard.

3. The irregular or amorphous masses
which we sometimes see in the thyroid gland,
Ovaries, uterus, testes, brain, liver, lungs,
spleen, kidneys, and heart, are supposed to
differ from the preceding classes, not only in
form, but in connexions and origin. They
appear to be united by continuity of substance
with the tissues in which they are developed,
and, in fact, to be altered portions of them. But
it is by no means proved that cellular tissue
may not, even in these cases, be the nidus of
such concretions, and that the organs have not
rather been absorbed to make room for them,
than transformed into them.

In false articulations, old cicatrices of the liver,
lungs, &c., we find a substance resembling car-
tilage ; but its description belongs to “ Fibro-
cartilage,” to which we refer. _

Chemical composition.—On this subject there
is some difference among writers; Dr. Davy*
found diarthrodial cartilage to consist of

Albumen.....see.ee0- 445
Water ......ecsesseses OOO
Phosphate of lime ...... 00°5

100°0

Berzelius professes his ignorance of its com-
position. Neither diarthrodial nor non-articular
cartilage yielded gelatine, and he doubts ** whe-
ther the mass which constitutes them be of a
peculiar nature, or similar to what we find in
the fibrous coat of arteries.’+ By boiling
costal and synarthrodial cartilages, gelatine is
developed. He looks on them to be imperfectly
developed bone, and to have the composition of
its animal part, with the addition of 3°402 per
cent of earth in the false ribs of a man of
twenty.

In 100 parts of this earth he gives the fol-
lowing analysis from Frommherz and Gugert:

Carbonate of soda .... 35°068
Sulphate of soda...... 24°241

Muriate of soda ...... 8°231
Phosphate of soda .... 0°925
Sulphate of potass .... 1°200
Carbonate of lime .... 18372
Phosphate of lime .... 4056
Phosphate of magnesia . 6°908

Oxyde of iron, and loss. 0°999
100°000

* Monro’s Elements of mpeg vol i,
+ Traité de Chimie, tom. vii. . 1833.

ce of an old man, who _
had had phymosis from the time of birth. =

CARTILAGE.

Pathological conditions—Cartilages are not
subject to many diseases. Inflammation, ulce-
ration, and ossification are almost the only ones
to which they are liable; and of these the first
is very indistinctly marked; the last scarcely
deserves to be called disease. Cartilages are
supposed to owe this exemption from morbid
actions to their extremely low degree of vitality.
Destitute of red vessels, and supplied with no
more nervous influence than is barely sufficient
to constitute them a part of the living system,
they escape those changes to which highly
organized parts are exposed; and, were it
not for their connexion with more delicate
and excitable tissues, their exemption would
be still more complete. Some eminent pa-
thologists have gone so far as to consider
them ineapable of any morbid action; espe-
cially the diarthrodial cartilages. “ Les carti-
lages diarthrodiaux ne jouissent point de la
vie,” says Cruveilhier, who asserts that he
could not excite disease in them by any of his
experiments; and that he saw them perfectly
sound in the midst of every other diseased
structure. Mr. Key* also seems to allow them
very little vitality in health, and to consider
them very nearly passive in what are called
their diseases.

Inflammation is rarely to be met with. Its
characters are so slightly marked in diarthro-
dial cartilage, that we infer its existence, not so
much from the signs which are present, as from
observing that ulceration is a common occur-
rence—a state which we suppose to have been
preceded by inflammation. The only marks of
inflammation to be seen, even when most de-
veloped, are a softening of the cartilage, and in
two instances detailed by Sir B. Brodie, vessels
injected with red blood could be traced extend-
ing from the bones into the cartilages covering
them. Severe pain accompanies this disease ;
but, as in all the cases on record, ulceration, or
some other disease was also present, it cannot
be determined how much of the pain belonged
exclusively to it. The costal cartilages are
subject to painful affections which usually
occur in patients who have had syphilis, or to
whom mercury has been administered inju-
diciously. These depend on inflammation of
the perichondrium. They may terminate in
ulceration or in osseous deposition, and have a
close resemblance to periostitis.

Ulceration of cartilage is a very common
occurrence in joints, but is extremely rare in
other situations. It may be met with at any

iod of life, or in any articulation, but it is in
the hip and knee we most frequently find it,
and in persons who have passed the age of
puberty and are under thirty or thirty-five.
A striking peculiarity attends this affection,
namely, that the formation of pus is by no
means a constant accompaniment. The form
and situations of ulcers in diarthrodial cartilages
are very various. Sometimes they are small and
deep ; sometimes very superficial, like an abra-
sion—at one time attacking the free, at another
the attached surface; and may commence in

* Medico-Chirurgical Transactions, vol. xviii.

499

the centre or at the circumference. These ulcers
may be divided into primary and secondary, the
former arising independently of any disease in
the adjoining tissues, the latter being preceded
by a morbid state of the bone or synovial
membrane.

‘The primary ulcer commences towards the
centre of the cartilage, and always on its free
surface. It is accompanied with much pain,
but when exposed to view exhibits no sign of
inflammation. There is no vascularity to be
observed, no granulations, frequently no pus,
nor any unhealthy appearance of the synovial
membrane. Should the ulcer, however, have
extended itself quite through the cartilage to
the bone, the latter usually becomes carious,
pus is secreted abundantly, and the synovial
membrane sympathizes. The surface of the
ulcer differs very much in different cases ; in
some it appears smooth, and of the colour of
healthy cartilage, as if a portion were chiselled
out. In others, and more generally, it is a little
yellowish, dull looking, and slightly irregular.
The edges are often irregular, never elevated
nor undermined. The ulceration sometimes
spreads superficially over a large extent; at
other times it is small and deep, or it may
destroy all the cartilage and expose the bone,
which will also be found diseased. Most
generally the remaining cartilage, if any, retains
its healthy structure to the very edge of the ab-
sorbed portion.

Another appearance is often observed; a part
of the cartilage is reduced to a fibrous state, the
fibres being attached at one extremity to the
bone, while at the other they are free, and have
no jateral connexion. This condition of carti-
lage is said, by Sir B. Brodie, to be frequently,
but not constantly, the first stage of ulceration 5
and he conceives it may often exist where no
ulceration is ever to follow. Mr. Key looks on
it as “a disease of a peculiar character.” And
we have frequently found it in the dissecting
room, where there was not the slightest mark
externally or internally of any other morbid
action. The writer has observed it oftener on the
patella than elsewhere ; and as this is so seldom
the part first involved in the ulcerative process,
it probably depends on an action of a different
nature. The writer has also seen it oftener in
joints long dead than in the more recent, and has
therefore thought it might possibly be caused,
in some cases at least, by the action of the
synovial fluid, or by decomposition.

Secondary ulceration may commence in the
bone or in the synovial membrane. (a) When
the bone is previously diseased, that side of the
cartilage which was turned to it is first affected.
The adhesion of the two tissues is diminished ;
we find it more easy to separate them. After
some time a separation actually takes place, and
a vascular net-work, sometimes a layer of granu-
lations, occupies the interval. The surround-
ing cartilage is softened. The ulcer, with cha-
racters differing little from the primary form,
goes on more or less rapidly, until an opening
is made quite through into the cavity of the
joint. When this opening is effected, the mat-
ter, which in this form of ulcer is always pre-

500

sent, finds its way into the synovial sac, and ex-
cites inflammation there.

_ The disease of the bone commonly giving
rise to this ulcer is the slow strumous affection
of the spongy extremities, so accurately de-
scribed by Sir B. Brodie, the symptoms of
which are familiar to every surgeon. A more
acute inflammation of the osseous tissue is oc-
casionally to be seen, and may be followed by a
disease of the same nature, or differing only in
the quickness of the course it pursues.

(6) Secondary inflammation extending from
the synovial membrane is most apt to attack
the edges of the cartilages in the first instance.
These are thinned, as if abraded, and over-
lapped by the vascular or disorganized mem-
brane. The bone remains sound, as in the
primary ulceration. For further particulars on
the ulceration of cartilage, see Joint.

Does fractured cartilage ever unite by cartilage?
It probably never does. The costal cartilages,
when broken, unite by lymph, which soon after
is converted in bone, but never appears to form
true cartilage. When a fracture extends into a
joint, as we often see in the condyles of the
humerus and femur, the divided cartilage is
united by a cicatrix, which is not truly car-
tilaginous. Neither does it appear that car-
tilage is ever regenerated. Laennec believed it
was: “in examining a knee-joint, he found in
the centre of the articulating surfaces, in place
of the natural cartilage, a thin cartilaginous
lamina, semitransparent, adherent to the bone;
the old cartilage formed around it a projecting
border, as if fimbriated.””*

This observation certainly was not enough to
establish its power of regeneration. We often
find in cases of gout and rheumatism, and
especially in the disease designated morbus core
senilis, that the cartilage is removed, and in its
place a compact shining layer of osseous sub-
stance like ivory deposited. This is not owing to
an ossification of the cartilage, for the cartilage is
often found completely absorbed, and the rough
bone exposed, which, if seen at a later period,
would doubtless be covered with this deposit to
prevent the disintegration of its cancellated
structure.

BIBLIOGRAPHY.—Hunter on the structure and
diseases of articulating cartilages, Philos. Trans.
1743. Haase, De fabrica cartilaginum, 4to. Lips.
1767. Authenrieth, De- gravioribus quibusdam
cartilaginum mutationibus, 8vo. Tiibing. 1798.
Mayo, Acute form of ulceration of the cartilages
of joints, Medico-Chirurg. Trans. vol. xi. Cru-
veilhier, Obs. sur les cartilages diarthrodiaux, et
les maladies des articulations, Archives Gén. de
Méd. t. iv. 1824; Ej. Usure des cartilages articu-
laires, Nouv. Biblioth. Méd. t. i. Observations
on accidental or loose cartilages may be found, by
Cruikshank, in Med. and Philos. Comm. of Edinb.
vol. iv. ; by Coley, in Med.-Chir. Trans vol. Vez
by Horne, in Trans. of a Society for Improv. Med.
and Chirurg. Knowledge, vol. i.; by Desault, in
his Jonrn. de Chirurg. t. ii. ; by Abernethy, in his
Surg. Observations; by Laennec, in the art. Car-
tilages Accidentels of the Dict. des Sc. Méd. ; by
Cruveilhier, in Nouv. Bib. Méd. t. i. 1827; &c.
And remarks on special forms of disease affecting
the cartilages occur in the general treatises on dis-

. Op. cit. p. 240,

CAVITY.

eases of the joints, as those of - *
Schreger, Wilson, and Scott.—Vide Bibliography of

ARTICULATION.
(Charles Benson.)

CAVITY, in anatomy, (cavitas; Fr. cavité ;
Germ. Hohle ; Ital. cavita.)—This term is used,
in anatomy, to signify any excavation or even
depression of more than ordinary depth, which
may exist in or between solid parts. Hence
we find cavities existing in bones, or formed
by the junction of one or more bones, which, as
they are severally destined for articulation with
other bones, or for the reception or transmis-
sion of certain tendons, vessels, &c. are de-
signated articular or non-articular. (See Bone.)

But we have likewise large excavations whose
walls are of a more complicated arrangement,
and which are destined to receive and protect
those organs which are concerned in the func-
tions of innervation, respiration, and digestion,
and throughout a large proportion of the classes
composing the animal kingdom are three in
number, namely, the Cepnatic or CraNnian
cavity, containing the brain—the Tsoracic
cavity, containing the organs of respiration—
and the ABDOMINAL cavity, containing the
organs of digestion and of the secretion of
urine. To this last is appended, as a continua-
tion, the Pretvic cavity, which is chiefly de-
voted to the organs of generation, as well as to
some of those connected with the urinary ex-
cretion. We refer for particulars connected
with the other cavities to the articles Cranium,
Tuorax, and Petvis, and proceed to consider
succinctly the anatomy of the AspominaL
Cavity in its Normal as well as Abnormal
conditions.*

AxspominaL Cavity, (in human anatomy.)

The annexed woodcut exhibits a vertical
section of the body intended to show the tho-
racic and abdominal cavities, from which the
viscera have been removed. A simple reference
to it and to fig. 204 will sufficiently explain the
form and boundaries of the latter cavity, which
have been already fully described in the article
AxspomeNn. Our object in the present article i
is to examine the abdominal cavity as it is }
brought under the eye of the anatomist, when
its contents have been exposed by removing or
cutting through the abdominal parietes.

* Some anatomists object to the use of the term
cavity, because, say they, every hollow in the
animal body is full. Such an objection, on the
principle of nature’s abhorrence of a vacuum,
would go to discard the use of the term, even from
ordinary discourse. Considering the word in re-
ference to its etymology, it is synonymous with
excavation, which in no way implies emptiness,
and it is in this sense that we must employ it —
in anatomical description. I apprehend that con-
fusion has arisen from employing the same word to
denote the excavation bounded by bone or by bone _
and muscle, in which the viscus or viscera are
lodged, and to indicate the bag or sac of the pee "
membrane by which each of the three great cavi- —
ties is lined. In this latter sense, the term cavity ©
is certainly not appropniates at least it may be —
most advantageously laid aside; and we can use,
without the same risk of confusion, the expression —
bag or sac of the peritoneum, pleura, &c. ie

CAVITY. 501

It rarely happens that we meet with an in-
stance in which the abdominal viscera have

not been more or less disturbed after death

from their natural relations to one another.

“During life the contractile walls of the ab-

domen, ever active, maintain such a uniform
degree of pressure on the contained organs,
that displacements or alterations of positions

‘are very rare occurrences excepting through
‘some preternatural opening in the abdominal

parietes. It is advisable to study the positions
of the contents of the abdomen in a body re-
cently dead, and which has not experienced
any degree of disturbance.

When the anterior wall of the abdomen has

‘been removed or freely laid open by a crucial

incision, the contents of the cavity are brought

into view in the following order : —

In the right hypochondriac region the liver

rojects to a slight extent below the inferior

rder of the chest. This, however, is not to
be regarded as the position of the liver during
life; the descent of that organ from behind the
shelter of the ribs is attributable to its gravita-
tion in consequence of the removal of the
support which it obtained from the pressure of
the anterior abdominal wall. The liver will
thus be found to extend more or less into the

proper epigastric region, covering and con-
cealing the lesser curvature of the stomach
with the gastro-hepatic omentum and the ante-
rior, or more correctly, the antero-superior
surface of the stomach to a variable extent.
In this region we likewise see, corresponding
pretty nearly to the cartilage of the ninth rib,
the fundus of the gall-bladder in some in-
stances completely covered by the liver, in
others projecting beyond it or only covered by
a duplicature of serous membrane which fills
up a natural notch in the liver. In the epigas-

i] Li

trium more or less of the stomach is seen, its
greater curvature projecting forwards, having
pendent from it the middle portion of the great
omentum; and the left hypochondrium often
(especially when the stomach is full) seems to
be wholly occupied by the splenic extremity of
the stomach, immediately below which there
is a portion of the transverse colon, just where
it is forming an angle with the descending
colon. Sometimes the anterior margin of the
spleen projects before it, and sometimes a still
greater portion of the spleen is visible, if that
organ be in a state of turgescence. Along the

502 CAV

inferior boundary of the epigastric region, and
projecting partly into that region and partly
into the umbilical below, the transverse arch
of the colon runs with a slight curve concave
backwards and downwards. The position of
this important portion of the great intestine is
always lower in the abdomen of a subject thus
opened than it can possibly be during life. In
fact, when the abdominal wall is unimpaired
and the usual compression is maintained, the
stomach and colon must be in very close appo-
sition with each other, so that it must be diffi-
cult, if not impossible, to make pressure from
without on the one without affecting the other
nearly to the same degree. The arch of the
colon is loosely covered on its anterior surface
by two laminz of peritoneum, which descend
from the greater curvature of the stomach and
entering into the umbilical region are reflected
upwards after a descent as far as the lowest
part of that region, forming a curtain which
covers the convolutions of the small intestine
beneath the transverse arch of the colon. This
curtain is the great Omentum or Epiploon,
( Omentum majus,) which, in the natural con-
dition of the parts during life, there is every
reason to believe is closely applied to the an-
terior surface. of the small intestine; much
variety, however, may be observed as to the
extent of its relation to this portion of the
intestinal canal, and it is difficult to account for
this variety. Thus we sometimes find the in-
testine uniformly covered by this membrane
more or less loaded with fat, descending as
low as the upper outlet of the pelvis; this
may be regarded as the normal state in the
adult. But at other times we find the omentum
so crumpled up or contracted, that the small
intestine is completely exposed, and it is only
by pulling down the omentum from the arch
of the colon towards which it is folded up or
crumpled, that we can form an estimate of its
extent. Again, in other cases we observe that
it is only long enough to descend halfway or a
little lower over the surface of the small intes-
tine. It is said to have less extent in females
who have borne many children than in any
others; I cannot confirm this statement, inas-
much as I have not unfrequently seen it of its
full dimensions in such subjects. In the na-
tural state of the parts, then, the whole of the
central portion of the umbilical region is oc-
cupied by the omentum, forming a moveable
curtain over the anterior surface of the con-
volutions of the jejunum and ilium.

The iliac region of the right side is occupied
by the cecum or caput coli, and in the lumbar
region of the same side the ascending colon is
visible, sometimes when distended projecting
considerably, at other times so contracted as to
appear sunk towards the posterior wall of this
region, and to allow of being overlapped and
concealed from view by some of the convo-
lutions of the small intestine. In the corres-
ponding regions of the left side the remaining
portions of the colon are seen, and they too
are very frequently, if not generally, closely
applied to the posterior wall: in the lumbar
region the descending colon is much more

ITY.

frequently in a contracted than in a distended
state, and in the iliac region, not occupying it
to the same extent as its fellow is occupied by
the ceecum, we find the sigmoid flexure of the
colon winding its curved course over the psoas
muscle, and sinking into the pelvis to assume
the name of rectum. The lower convolutions
of the small intestine invariably fill up the
superior outlet of the pelvis, and are found to
a greater or less extent in that cavity, in pro-
portion as the bladder and rectum are empty
or the reverse.

Such being the position of the parts as they
appear when the anatomist lays open the ab-
domen in a recent subject, we proceed now to
examine what parts are found in each com-
partment of this cavity, and the relation which
they bear to each other. We may observe,
in passing, that there cannot be much difference
in the position of the abdominal organs during
life, even in the varied attitudes of the body,
from that which we find them to possess in a
body recently dead. Making allowance for
the pressure which is maintained upon them
by the abdominal parietes, it is obvious that
the position of each organ during life will be
higher in the abdomen than that which it occu-
pies in the dead body; all the organs are more
firmly applied to one another and to the pos-
terior wall of the abdomen.

It is not, however, unimportant to bear in
mind that such is the nature of the contents
of the hollow abdominal viscera, and such the
rapidity with which they become accumulated,
that changes of relation. may be rapidly
effected. Thus the stomach, or any part of the
intestinal canal, may by a rapid accumulation
of air or any other matter within it, occupy
a much more extensive portion of the abdo-
men than it usually does in the natural state.

This is allowed by the extraordinary com-
pressibility of the other viscera, a com-
pressibility which is every day exemplified in }
pregnancy, aud in cases of ovarian dropsy, .
of ascites, &c. |

1. The epigastric region.—The right extre-
mity of this region or the right hypochondrium
is occupied almost entirely by the liver, which
is connected with the diaphragm and anterior
wall of the abdomen by the folds of perito-
neum which form what are called the ligaments
of the liver. When the left lobe of the liver
is raised up, we see the lesser or gastro-hepatic
omentum extended between the lesser curvature
of the stomach and the transverse fissure of
the liver. A defined margin terminates the
gastro-hepatic omentum on the right side, just
adjoining the neck of the gall-bladder: if the
finger be pushed underneath this margin from
right to left, it passes through ‘an opening which
leads into the cavity of the omentum, and if
continued downwards behind the stomach will
separate the lamine of the great omentum.
This opening is commonly known under the
name of the Foramen of Winslow: the lesser
omentum bounds it in front, behind it lie the —
supra-renal capsule, the venacava ascendens,and —
the psoas muscle, covered by a lamina of perito- _
neum which ascends towards the diaphragm, ©

4

CAVITY. 503

after having partly covered the duodenum*
The lesser splanchnic nerve will also be found
in this situation lying on the quadratus lum-
borum muscle and on the psoas, and descend-
ing to throw itself into the renal plexus. On
a a posterior to the lesser omentum the
inferior surface of the liver is in contact with
the kidney, and with the angle of junction of
the ascending and transverse portions of the
colon, as is proved by the frequent adhesion of
this intestine to the liver. The situation of
the gall-bladder in this region demands atten-
tion ;—its fundus corresponds to the cartilage
of the ninth rib, beneath which it sometimes
projects to an extent proportionate to the de-
gree to which it is distended ; hence it is evi-
dent that an unusually distended gall-bladder
is not unlikely to form a tumour below the
margin of the ribs presenting all the characters
of an hepatic abscess.t The gall-bladder is, in
this region, in close connexion either by its neck
or body, with the duodenum or tranverse colon,
a fact which explains the evacuation of gall-
stones into either of those intestines. The left
lobe of the liver projects more or less into the
central portion of the epigastric region, or that
which is called the proper epigastrium. Here
it is in contact by its concave surface with the
anterior superior surface of the pyloric half or
third of the stomach. This latter viscus when
contracted lies very far back in the epigastric
excavation, and extends towards the left side,
so as to occupy the left hypochondrium to a
great extent. Its pyloric third or half is in
contact with the liver, the remaining or cardiac
bate is in contact with the diaphragm ;

ence it is always the displaced organ in dia-
phragmatic hernia. This close connexion of
the stomach and diaphragm likewise explains
the peculiar sonorousness which percussion
frequently elicits over the left hypochondrium
and even for some distance up the anterior
surface of the thorax, so that when the sto-
mach is large and flatulent, it is often very
difficult to ascertain whether the sound pro-
duced and heard in this region results from an

effusion of air and liquid into the thorax, or

from such a stomach filled partly with liquid
and partly with air. When the stomach is
full, the aspect of its superior surface is more
directly upwards and less forwards than in the
empty state ; but a considerable portion of the
anterior part of this surface, as well as of the
greater curvature, is in contact with the abdo-
minal parietes. The great curvature of the
stomach for three-fifths of its extent towards
the pylorus is closely connected with the upper

<.

* Blandin records a remarkable case of internal
Strangulation which took place by the introduction
of a considerable portion of the small intestine
through the foramen of Winslow into the cavity of
the omentum, from which it escaped through a
lacerated opening in the transverse mesocolon
which firmly constricted a knuckle of the intestine
and occasioned mortification of it.— Anat. Topog.
p- 442.

+ See cases recorded by Andral, Clin. Med. t. iv.
and Graves, Dublin Hosp. Rep. vol. iv.

surface of the transverse arch of the colon,
and with the two anterior lamine of the great
omentum which come in contact along the line
of that curvature, enclosing between them the
anastomosis of the gastro-epiploic arteries.
Hence we sometimes find that, in cases of per-
foration of the stomach, the opening is filled up
by the adhesion of the wall of the colon to the
serous coat of the former viscus, and the effusion
of its contents is thereby prevented ; and it has
been said that fluids may pass through an
ulcer of the great curvature and be effused
between the lamine of the omentum, so as to
point externally as an abscess.* The extent of
the relation of the stomach to the liver varies ;
in some instances it extends as far outwards as
the gall-bladder; and Cruveilhier mentions a
case in which gall-stones were discharged into
the stomach in consequence of an adhesion
formed by its anterior surface with the gall-
bladder. The stomach rests by its posterior
and inferior surface on the superior lamina of
the transverse mesocolon, which forms a natural
floor to the epigastric region, and separating it
from the umbilical region. Posteriorly the
same lamina of the transverse mesocolon sepa-
rates it from the inferior transverse portion of
the duodenum and from the head of the pan-
creas, which again are separated from the spine
by the aorta and crura of the diaphragm.
The lobulus Spigelii of the liver is seen behind,
and to the left of the lesser curvature of the
stomach, and when the latter is drawn down-
wards and the liver forwards, this lobe projects,
pushing the gastro-hepatic omentum before it ;
the lesser curvature has likewise among its
connections posteriorly the cceliac axis and
solar plexus, and like the great curvature has
an arterial anastomosis running along it formed
by the superior pyloric and gastric arteries.
The spleen is very intimately connected by the
gastro-splenic omentum to the left extremity or
great cul-de-sac of the stomach, and seems,
as it were, moulded upon it, following it in its
movements, and each accompanying the other
in its displacements: behind this portion of
the stomach are the tail of the pancreas, the
left kidney, and supra-renal capsule. The
point of entrance of the csophagus into the
cardiac extremity of the stomach is overlapped
by the left lobe of the liver and its left lateral
ligament, and it rests upon the decussating
muscular bundles of the diaphragm.t

In the epigastric region we likewise find the
first portion of the duodenum passing from
left to right slightly upwards and backwards,
terminating at the neck of the gall-bladder,
with which it often contracts preternatural
adhesions. Behind this superior portion of
the duodenum, a little to the left of its ter-
mination, the ductus communis choledochus

% Ledran, quoted by Velpeau, Anat. Chir. t. ii.
p- 165.

+ From the relations of the stomach to the abdo-
minal parietes we are not surprised to read of fistu-
lous communications being formed between that
viscus and various regions of the abdominal surface.

504

descends to enter the middle portion of this
intestine, the upper part of which is likewise
found in this region. Here, too, we have the
upper half of the head of the pancreas, the
‘right gastro-epiploic and the gastro-duodenalis
arteries.

In proceeding to remove the parts which
lie most superficially in the epigastric region,
we notice on the right side the vessels and
nerves enclosed between the lamine of the
lesser omentum, viz. the hepatic artery and
its terminal branches, the vena porte, and
the hepatic and cystic ducts, with the com-
mencement of the ductus communis chole-
dochus, and entwining its filaments chiefly
around the hepatic arteries is the hepatic
plexus of nerves; several lymphatic vessels
of considerable size are also found here, and
some lymphatic ganglions, the enlargement of
which latter, whether acute or chronic, may retard
the passage of the bile and give rise to jaundice.
All these parts are invested and connected to
each other by the dense cellular membrane
called the capsule of Glisson. Behind the
liver, and closely lodged in a groove, and
sometimes a canal in its posterior thick margin,
is the vena cava ascendens, which is still more
intimately connected with the liver through
the branches of the vena cava hepatica, which
open into that portion of the ascending vein
which is lodged in the groove. To the right
of the vein are the supra-renal capsule and
the upper part of the kidney, and to its left,
and closely connected with the supra-renal
capsule, is the semilunar ganglion. Here,
likewise, are the renal or emulgent vessels
and the renal plexus of nerves.

In the centre of the epigastric region, on
removing the stomach, we open into the lesser
cavity of the peritoneum, of which the stomach
forms, in part, the anterior and superior boun-
dary. This cavity is bounded inferiorly and
posteriorly by the descending layer of the trans-
verse meso-colon, which covers the upper part
of the pancreas; above this latter gland is the
celiac axis, surrounded by the solar plexus of
nerves, giving off its terminal branches, of which
the hepatic passes towards the right side, and
forwards to the transverse fissure of the liver,
while the splenic directs itself tortuously towards
the left side, along the upper margin of the
pancreas. The pancreas itself is to be counted
among the parts contained in this region ; here
it is covered by the superior layer of the trans-
verse mesocolon, which alone separates it
from the posterior surface of the stomach;
hence this gland has sometimes, by contracting
an adhesion with the stomach, served to fill
up a perforation byan ulcer. Behind the pan-
creas are the vena porte and the conflux of
the splenic and superior mesenteric veins, the
superior mesenteric artery, and the nervous
plexus of the same name; by all of which
the gland is separated from the aorta, which,
again, with the pillars of the diaphragm and
some lymphatic glands, separates the pancreas
from the spine. To the right of the aorta, and
intervening between it and the right crus, are

CAVITY.

the thoracic duct and the vena azygos, and
external to each crus of the diaphragm the
great splanchnic nerve is seen to connect itself
with the semilunar ganglion. :

On the left side the gastro-splenic omentum
contains the vasa brevia and splenic arteries,
the splenic plexus of nerves, and the com-
mencement of the left gastro-epiploic artery ;
the great cul-de-sac of the stomach, and the
spleen cover here the left supra-renal capsule,
the semilunar ganglion and great splanchnic
nerve, the upper part of the left kidney, and
the renal vessels and nerves.

From the vast number and importance of
the parts contained in the epigastric region, it
cannot be a matter of surprise that it is fre-
quently the seat of disease, and that the most
serious consequences will often ensue upon
strong pressure or violence inflicted upon it.
It is universally known that syncope may be
induced or even sudden death occasioned by
a blow upon the epigastrium, even in a healthy
individual; and it seems to be the favourite
opinion that such results arise from the influence
exerted upon the immense nervous plexus
which is found here. Sometimes, however,
one or more of the viscera have experienced
injury, and cases of rupture of the spleen,
liver, gall-bladder, or duodenum from violence
inflicted on this region are not uncommon.*
Every practitioner is familiar with the existence
of epigastric pulsations, which, as they arise
from a variety of causes, form a subject of
great interest. Dr. Copland thus enumerates
these causes, and, indeed, most of them may
be deduced @ priori from a knowledge of the
anatomy of the region: a, nervous suscepti-
bility; 6, inflammation of the aorta; c, aneu-
rism of the aorta; d, adhesion of the pericar-
dium to the heart; e, tumours at the root of
the mesentery ; f, tumours of the stomach or
scirrhus of the pylorus; g, enlargement of the
pancreas; A, hypertrophy of the heart, parti-
cularly of its right side; 7, enlargement of the
inferior vena cava; k, hepatisation of the lower
portion of the lungs; /, enlargement of, or
abscess in, the liver.

Umbilical region.—This region is distinetly
and naturally separated from the epigastrium
by the transverse arch of the colon and the
transverse mesocolon. It is almost entirely
occupied in. the centre by the small intestines,
and on each side by the colon, either ascending
or descending. Deep seated and at the upper
part of the region, we notice the inferior portion —
of the duodenum, which is covered by the infe-
rior lamina of the transverse mesocolon, and ter-
minates on the left side of the spine, just where —
the mesentery commences. The superior me- —
senteric artery crosses above and in front of —
the duodenum, a few lines to the right of its
termination, and when the body is laid on the —
back the intestine seems to suffer a constriction —
from the artery. Such a constriction can hardly —

* See an interesting paper by Dr. Hart, in the jj
Dub. Hosp. Reports, vol. v. a
+ Dict. Pract. Med. art. Epigastrium. om

CAVITY.

exist during life, when the viscera of the abdo-
men are under the influence of the action of
: its walls, for then the direction of the superior
mesenteric artery is so little downwards and so
much forwards that it cannot. be said to exert
any pressure upon the intestine; yet it is
remarkable that in many cases of ruptured
___ intestine, the seat of the rupture has been a
__-very short way below the continuation of the
duodenum into the jejunum. The inferior
portion of the duodenum rests upon the vena
cava and the aorta, and is in contact with
these vessels by its posterior wall. The
inferior margin of this intestine descends to
very near the bifurcation of the aorta, leaving
no more than from one-half to three-fourths of
‘an inch interval. We notice, moreover, in
this region the obliquity of the mesentery,
the arterial and venous, nervous and lacteal
ramifications existing between its lamine and
the mesenteric glands or ganglions connected
with the lacteals, which ganglions are often
very few and much atrophied in old subjects.
The convolutions of the small intestine are
-covered in front by the omentum, and are very
closely in apposition with each other: hence
they become ‘ matted together’ by the lymph
effused in peritonitis, and hence, too, in per-
forations, effusion of the intestinal contents
by no means necessarily takes place. The
looseness of the intestinal convolutions and of
the mesentery by which those convolutions are
tied to the spine, admits not only of their
being liable to frequent introsusception, but
also of being strangulated by the twisting of a
knuckle of intestine. For the same reason it
is that we find this intestine forming most
of the hernie which protrude from the various
regions of the abdomen. The small intestine
occupies the whole central umbilical region,
extending likewise on either side into the lum-
bar regions and downwards into the pelvis.
Thus it forms a considerable mass interposed
between the anterior and posterior abdominal
walls, and it is easy to conceive how, during
_ an irregularly distended state of the intestine,
_ violence applied to the abdomen in front can
- cause a rupture of a part of it without occa-
_ Sioning any solution of continuity in the wall
_ of the abdomen.
_ The lamine of the mesentery pass back-
_ wards and outwards along the sides of the
_ Spine, and entering the lumbar regions become
continuous with the right and left mesocolons.
By their divergence in front of the spine they
form a triangular enclosure, the basis of which
is formed by the bodies of the vertebre. In
_ this space we find the aorta, and lower down
the primitive iliac arteries, the commencement
_ of the thoracic duct, the receptaculum chyli,
and several tributary lymphatics and lacteals
with their ganglions, the vena cava ascendens,
and the left renal vein, the lumbar arteries and
veins, and many nervous ramifications from
the sympathetic, and more on the sides the
lumbar ganglia of the same nerve; here also
_ we notice the fibrous insertions of the crura
of the diaphragm, and the anterior common
ligament of the vertebra. Each lamina of the
a VOL, I.

Sprite ml lh ht ibe A i i ARS: ARE AES OS

NALA em

505

mesentery, as it passes outwards, crosses over
the ureter lying on the psoas muscle, and the
spermatic artery with the accompanying veins,
and some of the musculo-cutaneous branches
of the lumbar plexus, and having entered
the lumbar region, covers the right and left
colons, forming, at its reflections on and off
the intestine, the mesocolons. Each of these
portions of the colon lies very nearly con-
nected to the posterior wall of each lumbar
region, having only the lower portion of the
kidney, with its surrounding adeps, interposed
above. In some instances a mesocolon does
not exist, and the colon is bound down to the
posterior wall of the lumbar region, so that
the posterior surface of the intestine uncovered
by peritoneum is in direct contact with the
quadratus lumborum muscle or the kidney,
having only cellular membrane or fat inter-
vening, and this occurs much more frequently
at the left than at the right side: hence the
not uncommon occurrence of lumbar abscess,
or renal abscess, or calculi being discharged
into the colon, and so finding their way out by
stool. The proximity too of the portions of
the colon to the ureters serves, as Velpeau has
remarked, to explain how pins, or beans, or
pieces of lead find their way into the bladder
and become the nuclei of calculi there,
or being impeded in their progress through
the ureter, the calculous matter concretes
around them in that canal. In confirmation
of this explanation, he relates a case which
occurred at La Pitié. A pin, the head of
which was still found in the colon, in which
it had excited considerable ulceration, had
passed also into the ureter, so that a calculus,
of which the pin formed the axis, projected
partly within and existed partly without the
canal of the ureter.* Whether the mesocolons
exist or not, the right and left colons are in
general so fixed in situ, that they rarely form
the contents of a hernial sac.

Hypogastric region.—The central portion of
this region is occupied by the continued con-
volutions of the small intestine. The right iliac
region is in general entirely or almost entirely
occupied by the cecum, which sometimes has
a mesocecum and sometimes not. In the
latter case, a little reticular cellular membrane,
and the fascia iliaca, are all that separate the
intestine from the surface of the iliacus in-
ternus muscle. Beneath the fascia the ilio-
scrotal and the inguino-cutaneous nerves are
seen passing outwards to their destination. The
internal iliac artery and vein lie along the inner
margin of the psoas muscle, covered by a thin
fibrous expansion, which is a process from the
iliac fascia, and deeply seated between the
psoas and iliacus internus muscles is the ante-
rior crural nerve. The external iliac arteries
are crossed at their origin by the ureters, and
along their course a few glands may be found
either at the sides or in front. This region is
one of great interest to the pathologist, in con-
sequence of the frequent occurrence of disease

* Velpeau, Anat. Chir, t. ii. p. 175.
2.L

506

in it, whether originating in the wall or in the
coecum.

There is no part of the intestinal canal in
which accumulations are more likely to take
place than in the cecum ; and it is now pretty
well ascertained by the researches of various
observers that inflammation is often pro-
pagated from the cecum distended with har-
dened feces to the cellular tissue and muscles
of the iliac fossa, thus exciting abscess, which
may open either externally through the abdo-
minal parietes or internally into the ceecum.*
By careful manual examination of the anterior
abdominal wall corresponding to this fossa,
we are in general able to detect even a slight
distension of the cecum, and percussion em-
ployed here will often afford considerable
assistance in forming a diagnosis. The ver-
miform appendix of the cecum frequently
hangs down into the pelvic cavity connected to
the cecum by a fold of serous membrane ;
at other times it lies in the iliac fossa, being
folded up under cover of a projecting portion
of the cecum, sometimes as a natural result,
and at others as an effect of morbid adhe-
sions.

The left iliac fossa contains the sigmoid
flexure of the colon, which from its cylindrical
form, as well as from the circumstance of
its being in general much contracted, does not
occupy that region to the same extent as the
right side is filled by the cecum. The sig-
moid flexure is here connected by a mesocolon
similar to that of the descending colon, and
its relations to the other parts contained in the
iliac fossa are pretty much the same as those
of the cecum on the right side. In the centre
of the hypogastric region we observe that the
posterior wall is formed by the last lumbar
vertebra and the promontory of the sacrum,
and this region is open below, whereby it com-
municates with. the pelvis through the superior
outlet. Hence along the posterior wall we find
the rectum with its mesorectum,the middlesacral
artery, and the hypogastric plexus of nerves ;
and some of the pelvic viscera under particular
conditions pass forwards into this region, and
even admit of being examined during life
through the anterior wall. Thus the bladder
under distension comes forward, and, as the
distension increases, ascends, so as often to
occupy the whole of this region to the ex-
clusion of its natural contents; so also the
uterus. The vas deferens in the male and the
round ligaments of the uterus in the female,
and in both the obliterated umbilical arteries,
the urachus and the spermatic vessels, are also
among the parts belonging to the hypogastric
region.

The preceding account of the abdominal
cavity as it is found upon dissection, has re-
ference chiefly to the adult male subject; but
there are certain differences in the relations and
positions of parts, dependent on sex and age,
to which it is highly important to pay due

* See Dance in Rep. Gén, d’Anat. et de Phys.

t. iv. p. 74; Meniere, Arch. Gén. de Méd. t. xvii.;

and Ferrall, Ed. Med. and Surg. Journal. No. 108,

CAVITY.

verse measurement of which will be found to

attention. In the adult female, the chief dif
ference arises out of the great size of the pelvis
and the consequent increase in the magnitude
of the lower part of the abdomen, the trans-

exceed that of the epigastric region, more
especially where that region has been arti-
ficially compressed and consequently dimi-
nished in its capacity, by the custom of wear-
ing tight stays. During pregnancy, which,
as being a natural change, may be not inap-
propriately noticed here, the female abdomen
experiences a very considerable alteration in
its form, capacity, direction, the relations of its

organs, and the order of its circulation. .

“In the first month,” says Blandin, “ it
seems to contract, and its walls to fall in upon
themselves; but afterwards opposite changes
take place. By reason of the resistance offered
by the pelvis, when the uterus begins to in-
crease, and especially when it has acquired a
certain size, it makes, as it were, a protrusion
upwards, and is carried into the supra-pelvic
part of the abdominal cavity, which it dilates,
especially in front, in consequence of which
the obliquity of the axis of that cavity for-
wards is diminished. The dilated uterus is
placed entirely in front, behind the anterior
abdominal wall, and presses the small intestine
and omentum towards the spine: the omen-
tum, however, is sometimes, though rarely,
found in front of the uterus. The diaphragm
is also pushed upwards and raised as high as
the level of the sixth dorsal vertebra: all the
peritoneal folds of the uterus are obliterated ;
the peritoneum no longer descends into the
pelvic excavation, the bladder and the rectum
are strongly compressed, and are in some de-
gree impeded in performing their functions ;
the uterus itself is inclined to one side, in con-
sequence of the projection of the vertebral
column, and generally to the right side, which,
according to Chaussier, is attributable to the
greater shortness of the round ligament of the
right side. Notwithstanding all this enlarge-
ment of the abdominal cavity, the viscera are
compressed more strongly than usual, and can
become protruded with greater facility, when
the distended and attenuated walls have lost
much of their power of resistance. The nor-
mal irritation of which the uterus is the seat,
causes a greater afflux of blood into the whole
inferior part of the vascular system, and into
its own vessels in particular.” *

During the development and growth of the —
walls of the abdominal cavity some interesting
changes are observed to take place in its shape,
capacity, and in the positions of the containe 4
viscera. The most remarkable characteristic
the abdomen at the earliest period is its v
great capacity when compared with the ot
cavities; this arises from the greatdevelopme
its contained organs. This great size, howeve
is manifest entirely in the umbilical region, |
neither the epigastric nor the hyp ic
be said to exceed their proportional
in the adult. On the contrary,

magnitu
both ne

* Blandin, Anat. Topog. p. 431.

CAVITY.

regions are proportionally much smaller than
in the adult; the epigastric, in consequence of
the contracted diameters of the thorax, but more
particularly in consequence of the small size of
the vault which is formed by the diaphragm ;
and the hy tric by reason of the imper-
fectly developed state of the pelvis. Hence,
then, we find that most of the viscera extend
more or less into the middle or umbilical
region, which thus exhibits a very great en-
largement. The liver is the viscus which
exhibits the most remarkable degree of enlarge-
ment; its two lateral lobes present but little
difference in size, it extends laterally so as to
occupy nearly the whole epigastrium, leaving
but a small space at the left side for the
stomach and spleen; it passes considerably
beyond the inferior margin of the ribs, so that
a great portion of it is found in the umbilical
region, extending even to the hypogastrium.
This great extent of space occupied by the
liver necessarily causes corresponding altera-
tions in the positions of the neighbouring vis-
cera, and of none more than the.stomach. The
direction of this organ is nearly perpendi-
cular, its pyloric extremity is found a little
to the right in the umbilical region, while
the aspect of its splenic end is upwards and
to the left; its great curvature looks to the
left side and downwards, and its lesser cur-
vature to the right and upwards. The spleen
is not altogether contained in the left hy-
payee but also extends into the left
umbar region, and may be felt below the
false ribs. The duodenum does not change
its positive situation with reference to the
spine, but, in consequence of the position of
e stomach, its curves are more marked, the
Superior portion passes more decidedly up-
wards, and the whole duodenum is to a greater
extent covered by the stomach. The rest of the
small intestine is crowded backwards against
the spine, and in consequence of the non-deve-
lopment of the pelvis is found entirely in the
_ umbilical region; nor is it covered by the
| omentum, which as yet has attained but a very
small size. At this early period, moreover, the

_ bladder is an abdominal viscus; in general,
capacious and of a cylindrical form, it
extends out of the pelvis to within a very short
distance of the umbilicus, to which it is con-
nected by the urachus, so that it occupies a
considerable portion of the hypogastric and a
_ small part of theumbilical regions; consequently.
as Portal remarks, the shortest route by which
the bladder can be reached at this early age is
according to the method of the suprapubic
tion, and it is only a small portion of the
neck of the bladder which is at all in relation
with the perineum. A considerable portion of
_ the rectum, also, is found in the hypogastrium,
and in the female the uterus and ovaries and
the Fallopian tubes. Prior to the seventh or
_ eighth month of intra-uterine life, when the tes-
les enter the scrotum, they are found suc-
ssively as they. descend in different regions of
the abdominal cavity, at first in the lumbar
eee immediately beneath the kidneys, and
at different heights along the inner side of

507

the iliac fosse ; we also observe here that pro-
cess of peritoneum connected with the testicle,
and extending from it to the inguinal canal,
which is known by the name of the diverticu-
lum of Nuck: a similar process exists in a
much less developed condition in the female
connected with the round ligament. The prin-
cipal difference observable, as regards the large
intestine in the foetus at its full period, consists
in the great curvature of that portion of it that
is found in the left iliac region, occasioned by
the narrowness of the pelvis admitting but a
small part of the rectum.* In the progressive
development which takes place during intra-
uterine life, the position of this as well as of the
other portions of the intestinal canal presents dif-
ferences which it does not belong to the present
article to examine. (See InrestrnaL CaNaL.)

The capacity of the abdominal cavity and
the position of some of its contained organs,
as they thus exist in the feetus at its full period,
continue pretty nearly the same for some time
after birth. The enlargement, however, of the
vault of the diaphragm increases the capacity
of the epigastrium, while the gradual diminu-
tion of the liver affords room for the passage
of more organs from the umbilical region up-
wards, and the stomach is allowed to take a
more horizontal direction. These changes,
which are gradual in the periods of life prior
to puberty, become most manifest when the
arrival of that period gives rise to the enlarge-
ment of the pelvis; then the umbilical region
is as it were relieved from its overloaded state ;
the belly is less prominent, for the bladder
now occupies its proper place in the pelvic
cavity; the rectum, too, sinks into it, and many
of the convolutions of the small intestine are
found in it: thus, by the enlargement of the
hypochondria in the first instance, and subse-
quently by the development of the pelvis, the
three subdivisions of the abdominal cavity
assume those proportions in their respective
magnitudes which are characteristic of the
adult period.

In considering the probable amount of in-
jury inflicted by wounds which may have pene-
trated the abdominal cavity, we must take into
account the changes which the different atti-
tudes of the body occasion in the positions of
the viscera. These changes cannot be exten-
sive, and only regard the position of each
viscus with reference to the whole cavity, the
relations of that viscus to the neighbouring
ones being unaltered, or nearly so. They take
place in obedience to the law of gravitation,
and it is so easy, by a little reflection, to de-
duce what the changes must be, keeping in
mind the various means made use of to limit
and prevent displacement, that it seems unne-
cessary to do more here than allude to the fact
that the viscera are altered in position under
the influence of such a cause.

ABNORMAL CONDITIONS OF THE ABDOMI-
NAL CAviTy.—All the abnormal conditions of

* See on this subject Portal, Anat. Méd. tom. v.
Blandin, Anat. Topog. and Meckel, Anat. Gen.

Desc, et Path, tom, ii.
rR

508

the abdomen may be considered under two
heads: 1. as they regard the parietes of the
cavity; and, 2. as they refer to the positions of
the contained organs. We shall first examine
the abnormal conditions of the parietes.

Congenital malformations of the abdominal
parietes.—The first class of these malformations
which demands consideration is that which de-
pends on a defect in the development of the
structures which form the abdominal walls, and
these are by far the most numerous. In ex-
amining them it is to be borne in mind that
many of the abdominal viscera exist before the
walls of the cavity, which are formed around
the viscera, and that the anterior wall is later in
its formation than any of the others. The ca-
vity containing the viscera seems at first to be
a continuation of that of the umbilical cord,
its walls being continued from the sheath of
the cord. A distinct separation does not appear
to take place until the skin has become deve-
loped, when a line of demarcation is evident
between the skin of the abdomen and the
sheath of the cord.

The anterior wall may be deficient on
both sides to a greater or less extent, the
lateral and posterior being also more or less
involved. The maximum is when the defect
extends not only throughout the whole anterior
abdominal wall, but also to that of the thorax,
leaving all the viscera of both abdomen and
thorax visible, being covered only by a thin
membrane; and frequently congenital deficien-
cies of the lower part of the anterior wall of the
thorax are accompanied by a more or less ex-
tensive defect of the upper part of the same
wall of the abdomen, and the heart is included
with the abdominal viscera, which are rendered
visible, and which, in some instances, protrude
forwards. There may, however, be a con-
genital deficiency of, or fissure in the deeper
seated elements of the anterior abdominal and
thoracic wall, and yet the skin remain per-
fect and cover the protruded viscera.* But
the thoracic parietes may be perfect, and yet
there may exist an imperfect condition of the
abdominal parietes to a greater or less extent,
which imperfection evidently results from the
continuance of a greater or less portion of the
abdominal wall in that condition in which it
naturally exists in the early stages of fetal
development. In such cases the viscera are
covered by an expansion which is continuous
with the sheath of the umbilical cord. When
the deficiency of the abdominal wall exists to
a great extent, the tumour formed by the pro-
truding viscera is designated by the term even-
tration ; butif the defect be very limited, and
exist, as it generally does, at the base of the
umbilical cord, then the protrusion is an exvom-
phalos or congenital umbilical hernia. Both,
as Isidore Geoffroy St. Hilaire remarks, are
results of an arrest in the development of the
abdominal walls, with this difference, that in
the former the cessation of development takes

* See Geoffroy St. Hilaire’s description and plate
of an eh eee asad foetus : Monstruosités
Humaines, pp. 183 & seqq. plate 15.

CAVITY.

pasts an early period of foeta

the latter a6 late period. In

with the same laws, under the inf
which the arrest a develop pha
we find that, as in the progress of the nature
formation, the small intestine is the last to
enter the abdominal cavity, so a larger or
smaller portion of that intestine is g
found in the tumour of a congenital exom-
phalos. The nature of the contents of an
eventration depends evidently on the extent of —
the deficiency and the region of the abdomen —
which is most involved. ae

In some instances the peritoneum is deficient —
to an extent corresponding to that of the defi- —
ciency of the abdominal parietes. This isa —
rare occurrence, and is generally met with where
the defect of development is very extensive.*
There are cases, however, where, although the
defect was small, the peritoneum was absent
to a corresponding extent, and the intestines
protruded through the opening in a naked
state.t

The congenital inguinal hernia must likewise
be referred to an arrest in the development
of a very small portion of the anterior abdo-
minal wall. The canal of communication
which at one period exists between the peri-
toneal sac and the sac of the tunica vaginalis
remains pervious, the natural process by which
it is closed having been arrested. ‘This mode
of explaining the formation of congenital bubo-
nocele does not preclude the possibility of its
accidental occurrence, the material which closes
the canal having given way under the influence ~
of some force applied to it.

The superior wall of the abdomen sometimes
presents a defect of development, giving rise
to the congenital perforation of the diaphragm,
through which hernie take place into the
thorax. Such a perforation may exist on either
side, although it is much more frequently
found upon the left. (See DrapHracm.)

The malformation commonly known under
the name of ‘ extroversion of the bladder,’ has
also connected with it an imperfect state of the
anterior abdominal wall inferiorly, in conse-
quence of the separation of the ossa pubis and
of the recti abdominis muscles, and I be- —
lieve, in general, the absence of the pyrami- —
dales. (See BLapper, ABNORMAL ANATOMY.) ©
In these cases the umbilicus is generally situ-_
ated much lower than usual, and some writers —
have fallen into the absurd error of supposing —
that it was absent altogether, in consequence

aa

My
BT)

ra”

* See a case by Ruysch, (observat. Ixxii.}
in which the stomach, intestines, and spleen wer
situated externally to the cavity of the abdomet
Also one by Robinson, in which the defect «
tended from the abdomen to the umbilicus. An
Journal of Med. Sc. Feb. 1833, p. 346; and a‘
interesting and well-narrated one by my lear
friend Dr. Montgomery, in the Trans. Coll. P
Dub. vol.i. New Series. See also several othere
referred to in Meckel, Handbuch Der Pa
Anatomie, Band. i. p. 97—139.
+t See Fried, de fcetu intestinis plane n
abdomen propendentibus nato, in Sandifo
dissert. t. i. Also Howell, in London
Phys. Journal, vol. xlv. 1821,

a ee eS

er a
“

oe

CELLULAR TISSUE.

of its having escaped their notice by being
— and concealed by the protruded blad-
er.

A second class of congenital malformations
of the abdominal parietes arises from an excess
in the development of certain parts, as a nu-
merical increase in the muscles, vessels, or
nerves entering into the formation of the abdo-
minal parietes, or from the development of a
part of a second fetus in connexion with the
abdomen. Of the former it is extremely rare
to meet with instances among the muscles or
vessels of the abdomen; occasionally we do
find an unimportant increase in the number of
the costal attachments of one or more of the
muscles. As to the latter several cases are
recorded in which foetuses exhibited an arm or
leg, or even a portion of the trunk of another
implanted upon the abdominal wall, or, as is
a very rare occurrence, included in it; con-
Stituting a subdivision of that form of mon-
strosity which has been called Diplogenesis.
Werefer to the article Monsrrosiry for details
on this subject.

Morbid conditions of the abdominal parietes.
—These are such as are common to all parts
compounded of the same elements as enter into
the formation of the abdominal walls, which
it would be superfluous to particularise here.

Congenital malformations of the abdominal
cavity.—In many acephalous foetuses the ab-
dominal cavity is more or less curtailed of its
due proportions, the deficiency existing at its
saperior part. Where the inferior part of the
thorax or the pelvis is malformed, the abdo-
minal cavity will also be necessarily more or
less affected.

Under this head we may refer to the ano-
malies which arise from the congenital mal-
meyer of the viscera, which may extend to

whole contents of the abdomen, or may
affect only one or more viscera. Such are the
cases of complete transposition of the viscera,
where those which in the normal state are on the
right side are found upon the left, and vice versd;
thus the liver is found on the left, the pylorus
on the left, the cardiac extremity of the sto-
mach and the spleen on the right, &c. &e.
The aorta and vena cava too change places, and
the openings in the diaphragm alter their po-
sitions along with the parts which respectively
pass through them. The same transposition
ageeed extends also to the thoracic viscera.
n many of the instances in which this trans-
ition has been observed, the individuals have
ived to the adult period of life without ex-
hibiting any symptom indicative of the unusual
_ position of the internal organs.*
_ Single viscera are likewise often found trans-
posed or in unusual positions, occasioning
necessarily corresponding changes in the parts
which are connected with them. It is unne-
_ cessary to allude further to them here, as they

* See Metzger de Translocatione Viscerum,1779 ;

509

will be treated of in the articles appropriated
to those viscera.

The morbid conditions of the abdominal
cavity are the results of disease affecting its
lining membrane or its contained viscera and
other parts intimately connected with it. See
Perironeum and InrestinaL Canat.

For the Bibliography see that of ABDOMEN and

INTESTINAL CANAL,
(R. B. Todd.)

CELLULAR TISSUE. — Tela cellulosa,
textus mucosus, corpus, cribrosum, cellular mem-
brane, reticular membrane, filamentous, areolar,
laminar tissue, &e. (Fr. tissu celluleuxr ; Germ.
Zellgeweben..) The cellular tissue is the most
universally diffused element of organization,
and constitutes the basis of every animal body.
It consists of a soft, areolated, and elastic sub-
stance. A somewhat similar structure also
exists in vegetables, constituting their most
simple or elementary texture. ;

In systematic works the cellular tissue 1s
generally considered as a solid substance; but
as it really exists in the animal body, it is a
compound of solid and fluid materials; for in no
part of any animal is the cellular membrane
ever entirely devoid of fluid. This union of
fluid and solid parts is indeed indispensable to
organization, since there is no animal, or even
vegetable, in which it may not be demonstrated.
In the zoophyte the entire body appears to
consist of the cellular tissue, and even in man
it enters so largely into the formation of the
different organs, pervading equally the most
delicate and the most solid parts, that it con-
stitutes a species of mould of the whole body
and of its individual parts; indeed, if we ex-
cept the enamel of the teeth, and, as some
authorities contend, also the nails, the hairs,
and the epidermis, there is no solid in which it
may not be detected.

Many anatomists have included the adipose
tissue under the general denomination of cel-
lular membrane, but as the vesicles of the
former are distinct from the cells of the latter,
both as regards their formation and the nature
of their contents, we rather incline to adopt the
views of Malpighi, W. Hunter, Béclard, and
others, who contend that the adipose and cellu-
lar tissues are distinct and separate structures,
(See Aprpose TIssvuE.)

Arrangement.—The most striking and im-
portant fact relative to the cellular tissue is its
uninterrupted continuity throughout the whole
bedy, there being no part or region, however
insulated it may appear to be, in which this
communication may not be demonstrated.
Whilst we fully admit this general communica-
tion, it is yet necessary to state that the cellular
tissue may be appropriately divided into two
parts: the first division, called from its dis-
position the common or interstitial portion
(textus cellularis intermedius vel larus ), is that

also instances in Haller, Op. Minora, t. iii. ; and
several cases of modern date, of which one of the
“most complete is that published by Bryan in the
tions of the Irish College of Physicians,

which occupies the spaces left between the
various organs in all parts of the body; the
second division is distinguished by the name
of the special cellular membrane (¢. cellularés

4 vol, iv.

510

strictus, t. cellularis stipatus), because it is
et 28 to the several constituent parts of the

y, investing each of them, and penetrating
into their internal structure.

Of the common cellular membrane.—It is in
this division that the connection to which we
have just referred is most free. Thus in the
subcutaneous tissue placed between the skin
and the fascie of the muscles, there is an uni-
versal and evident communication. Again,
in the head, the cellular membrane of the exter-
nal parts communicates with that of the internal
through all the natural apertures—through the
foramina of the base and other regions of the
skull. From the face and cranium the con-
nexion may readily be traced to the neck,
whence, after having pervaded all its parts, it
passes in one direction behind the sternum
and upper ribs to the thoracic cavity; and in
another underneath the clavicle and scapula on
either side, to the arm-pit, which may be re-
garded as the common point of junction be-
tween the cellular substance of the neck, the
trunk, and upper extremity.

The cellular tissue of the thorax is continuous
with that of the abdomen through the openings
of the diaphragm, and particularly beneath the
sternum, around the aorta, the inferior vena
cava, and the cesophagus. Ina similar manner
the connexion may be followed from the abdo-
men to the pelvis; from the former of these
cavities under the crural arch to the inguinal
region, which constitutes the point of union
between the trunk and the lower extremity;
whilst from the pelvis the communication ex-
tends in one direction by the side of the rectum
and urethra to the perineum, scrotum, and
penis ; and in another by the obturator fora-
men and the ischiatic notch to the thigh.

Tn addition to these, which are the principal
connexions, the common cellular membrane is
united in every direction with the special di-
vision ; the details, however, of these commu-
nications belong to the descriptive anatomy of
the several regions, to the articles on which the
reader is referred.

The quantity of the interstitial tissue varies
according to the age and temperament of the
individual, and to the region of the body in
which it is examined; but, independently of
any original differences which exist, it is well
known that the mode of living and habits of the
individual have a great influence in this respect :
thus an habitual full diet, especially if con-
joined with indolence, causes a great accumu-
lation of the cellular substance; whilst, on the
contrary, a spare or moderate diet and exercise
will reduce it in a remarkable degree. These
differences depend, probably, more on the accu-
mulation of serous fluid and on the repletion of

‘the bloodvessels, than on the actual increase
of the proper filamentous tissue: we can in this
manner, and in no other, understand how, by
by what in England is called training, the bulk
of the body may he so rapidly diminished.

The proportion of this tissue varies also in
the different regions of the body; but as it is
in an especial manner subservient to the pro-
duction of free motion, it is principally accu-

CELLULAR TISSUE.

mulat ed in those . r which } : Pe iF mo |
able. It is on account that it ab

the face ially around the glob
and ‘about a chcaless and also on the fe
of the neck and of the trunk in general. |
limbs it is met with in considerable quanti
the flexures of the joints, in the axilla,
elbow, the wrist, and in the palm of the he
also in the groin, in the ham, in the front of the
ankle, and in the sole of the foot. The super-
ficial muscles, which are very moveable, are
separated from each other by thicker layers of ©
membrane than the deeper-seated and more
fixed. It may also be remarked that those —
important organs, which are most liable by their _
structure or connexions to rupture or other —
effects of external violence, are carefully pro-
tected by being lodged in a large quantity of —
cellular substance. It is thus that we find the
pancreas and the kidneys enveloped in this
tissue in the abdomen; the bladder and genital
organs in the pelvis; and the bloodvessels and
nerves in all parts of the body. &

Of the special cellular membrane. — Each
organ in the body is invested in a proper cover-
ing of the cellular tissue, and also receives into
its interior, processes which envelope and join
together its component parts.

The investing cellular membrane (¢. cellu-
laris strictus ) is united by one of its surfaces,
the external, with the general cellular tissue,
and by the other or internal with that entering
into the organ. It presents many peculiarities
as to the mode of its connexion; the solid
parts, for instance, as the glands, muscles, and
nerves, are entirely surrounded by cellular
envelopes; and a somewhat similar disposition
is observed around the bloodvessels, lympha-
tics, and excretory tubes. On the contrary,
the skin, the mucous and serous membranes,
having one surface free or unattached, are only
connected on one side with the cellular tissue,
which is distinguished according to its situation,
by the terms subcutaneous, submucous, and
subserous cellular tissue. The covering thus
afforded to each individual organ serves in a
certain degree to insulate and separate it from
the surrounding structures, and in this manner
it often tends to limit the progress of disease; —
but as we have just seen that this covering is
united both to the interstitial and to the pene-
trating cellular tissue, it would be equally con-
trary to reason and experience to expect that it
should constitute, as some authorities have con-
tended that it does, a species of atmosphere
around the various organs, confining their natu-
ral actions and morbid phenomena. Ae:

The penetrating cellular tissue (¢. cellular
stipatus ) constitutes so essential a part |
organized structures, that there is no organ”
which it may not be detected. It exists”
the substance of bone, cartilage, and ligam
although it is distinguished in these struct
with difficulty, in consequence of their g
density ; it penetrates between the most min
fibres of the muscles and nerves; be
coats of the bloodvessels and lym]
between the layers composing t
muegus membranes ; and lastly, |

CELLULAR TISSUE.

the substance of the absorbent and secreting
glands, investing their several component parts.

Structure and organization.—If a portion of
cellular tissue void of adipose substance be ex-
amined with the naked eye, and for this purpose
that which intervenes between very recent muscu-
lar fibres may be advantageously selected, it will
be seen that it is composed of an immense num-
ber of delicate and semi-transparent filaments,
having very much the appearance of the finest
threads of a spider’s web. These fibrils cross
each other in various directions, and in this
Manner intercept innumerable spaces, which
communicate one with another, and exhibit a
vast variety of figures. The small spaces or
areole which are thus produced constitute what
are called the ced/ls of this tissue; but as there
is nothing determinate either in their size or
shape, which evidently vary according to the
degree of traction exercised in separating the
filaments ; as they communicate together, and
consequently are not circumscribed; as they
are in fact simply the interstices left between
the fibres, the expression in common use is
calculated to convey an erroneous idea of the
real nature of these spaces.

If the investigation be prosecuted with the
aid of a powerful microscope, a very beautiful
appearance will be presented, of which it is
impossible to convey an adequate idea by any
description. We shall still observe fibres cross-
ing in all directions ; but although I have had
many favourable opportunities of making these
observations, I have never been able to detect
in the cellular fibre that linear arrangement of
globules described by Dr. Milne Edwards, and
which has of late years been very generally
Supposed to pervade all the elementary fibres of
the body. A number of globular particles may,
it is true, be seen at irregular distances, either
clustered together or dispersed in an isolated
Manner, but they do not enter into the forma-
tion of the fibre. The results, then, of careful
inspection disprove the ideas of former anato-
misis, some of whom, Ruysch and Mascagni
for example, supposed that the cellular fibre
‘was entirely vascular, whilst others imagined
it to be an expansion of the nerves: it is now
generally admitted that the basis of the cel-
lular substance is a solid and elementary fibre ;
and although to the naked eye it often presents
a membranous form, yet microscopical observa-
tion evinces that the plates of membrane are
distinctly composed of solid fibres. The in-
terstices or cells always contain in health a
very thin albuminous fluid, which has a great
resemblance to the secretion of the serous mem-
branes, and also to the serum of the blood;
and hence it is often termed the cellular serosity.
This fluid, which must be regarded as an in-
tegrant part of this tissue, has a great influence
on its properties, so that if it be entirely re-
moved, as by desiccation, the membrane be-
comes hard and brittle, and its elasticity is
almost lost ; or if it be accumulated in excess,
as we often see it in disease, the elastic force is
also destroyed.

Bloodvessels and lymphatics —An_ inquiry
into the relations which exist between the cel-

510

lular and vascular tissues, would lead to the
important question, how far vascularity is essen-
tial to organization? Without entering into
this investigation, it may be remarked that the
cellular substance is provided with blood-
vessels; and although the greater number of
these merely traverse the membrane in order to
reach other parts, yet the phenomena of nutri-
tion and absorption shew that a vascular appa-
ratus must exist in connexion with the cellular
tissue.

Nerves.—It is impossible to trace any ner-
vous filaments to the cellular fibres, although
such threads may be seen passing between them
to the neighbouring organs. The insensibility
in its healthy state also seems to indicate the
absence of nerves; but as pain is experienced
during inflammation, we must admit the ex-
istence of some communication with the senso-
rium. .

Chemical composition.—The cellular sub-
stance contains, like all the soft solids of the
body, a large quantity of water: when this is
evaporated, the fibres and cells adhere to each
other, and present a membranous appearance.
Analysis shews that albumen and gelatine com-
pose this substance ; the former predominating,
and being in a state of coagulation, bestows
on it the necessary degree of firmness and re-
sistance.

Properties—As we shall have occasion in
a future article (see MremsBrane) to consider
this subject more minutely, it will suffice if we
here remark that the most important property
of the cellular substance is a species of contrac-
tion which produces in all the soft parts a con-
stant state of tension or tone, which is one of
the most remarkable qualities of living bodies.
The cause of this peculiar condition, in what-
ever part it is evinced,—in the skin, in the
cellular tissue, in the muscles, in the vessels,
&c.—is the result of a property inherent in mem-
branous matter, which some authorities refer to
muscular contractility, and others to elasticity ;
whilst many eminent physiologists, denying
both these hypotheses, conceive that the con-
traction to which we are alluding is of a
character sui generis, and which they have
called tonicity, vis cellulosa, tonic contraction,
contractility of tissue, &c. I confess that none of
these theories have ever been to me satisfactory ;
because, as regards the first, there is no resem-
blance between the phenomena connected with
the contraction of membranous parts, and those
of muscular contraction ; whilst, as respects the
second, the resiliency by which the skin re-
covers itself after pressure has been made on
the external surface, and the retraction and
separation of the sides of an incision inflicted
on the integument, being observed only during
life, and never after death, prove that the results
of cellular contraction are, in some important
respects, different from those of common elas-
ticity. Those writers who, in consequence of

the difficulty of referring the phenomena under

consideration to either of the known causes of
contraction, viz., muscular contractility and
elasticity, have imagined the existence of a new
kind of contractile power, have, without ad-

512

ducing any sufficient proof in corroboration of
their views, had recourse to an expedient but
too frequently adopted by physiologists when
the real nature of any vital process escapes their
detection.

The only way in which the apparently con-
tradictory results of experiment and observation
can be reconciled, is by attending to a combina-
tion of vital and physical processes, that has
been too much neglected in investigating the
characters of living bodies; that is to say, it
must be recollected that “life,” to borrow the
philosophic expression of Dr. Arnott,* “is a
superstructure on physics and chemistry,” and
that those phenomena which are essentially de-
pendent on the ordinary laws of matter are
controlled and modified by the superior prin-
ciple of life. In the case of the cellular sub-
stance this remark is peculiarly applicable; and
from reflecting on all the facts relative to that
tissue both in a state of health and disease,
I have arrived at the conclusion that the phe-
nomena of its contractile force are the com-
bined results of one of the common proper-
ties of matter, viz., elasticity; and of a vital
process, viz., nutrition. It is a well-known
fact that the existence of elasticity in any inor-
ganic substance requires a particular state or
arrangement of its particles, and that if the
necessary condition be but partly fulfilled, or
be entirely wanting, that property is only
slightly displayed, or is totally absent. The
same principle strictly applies to the living
body; and in the cellular substance the required
condition is, a definite proportion between the
solid fibres and the interstitial fluids, which
state 1s maintained by the agents of the circu-
lation and secretion, namely, the bloodvessels
and lymphatics. Any thing which interferes
with this proportion, either the excess of fluids,
as in anasarca or phlegmonous erysipelas, or
the diminution of the humours, as in old age
and in many diseases, will impair or destroy the
phenomena observable in the sound state of the
cellular membrane, and will explain in the
former case, the pitting which is seen on making
pressure on the skin; and in the latter, that
flabbiness and wrinkling of the integument
about the face and other parts of the body, so
characteristic of those advanced in life or re-
duced by disease. We can in this manner
understand how a class of phenomena may be
dependent on a physical property, and yet
be modified by the condition of the vital powers,
so as to become impaired by disease, and
destroyed by death.

The exhalation and absorption of which the
cellular substance is the seat, have been sup-
er by many high authorities to be effected

y its elastic contractility; but it is probable
that these phenomena, although in part de-
pendent on that property, are principally pro-
duced by the power of imbibition, which, ac-
cording to the experiments of MM. Magendie
and Fodéra, exists in all the soft parts of the
body.

Functions.—The offices accomplished by

* Elem. of Physics, Introd. p. xxvi.

CELLULAR TISSUE.

this substance in the economy si m to
that of uniting together the various co

s of the body, and of keeping them in situ —
by its contractile force ; secondly, of facilitating

their movements by means of its lubricating _
fluid, and thus preventing the injurious effects —
of friction and concussion ; and lastly, of fur-
nishing an appropriate structure for their recep-
tion. It has also been supposed that, being a
bad conductor of caloric, it will tend to pre- _
serve the uniform temperature of the body.

Development.—The first trace of an organized
substance observed in the embryo consists of a
very soft and pulpy cellular tissue, which at
this early period is loaded with fluid; and
being homogeneous in its nature, it presents
neither fibres nor interstices, although it may
be readily permeated by air or liquids, so as to
produce small cells, and may likewise be drawn
out into glutinous filaments. In proportion as
the several organs become developed, it acquires
greater consistency, and is at the same time
diminished in quantity. At the period of birth
it is still, however, in a very soft and imperfect
state, and only acquires its proper density by
slow degrees; in old age, being deprived of a
large portion of its fluid, and perhaps otherwise
deteriorated, it loses much of its elastic force ;
and this circumstance, joined to its diminished
bulk, is a principal cause of that loss of rotun-
dity so conspicuous in the bodies of aged
persons, and of the flabbiness of the several
organs.

The power of reproduction is greater in this
than in any other tissue, so that it is not only
readily formed again within certain limits when
it has been destroyed, but it even appears to
supply the place of other and dissimilar struc-
tures which may have been lost by disease.

The cellular substance presents but few mo-
difications of importance when examined in
the different classes of animals, except, indeed,
that it is generally believed to constitute the
entire body in those species that are placed at
the bottom of the scale. The Porifera afford an
example of the simplest form of the cellular tex-
ture with which we are at present acquainted ;
the body of these animals consists of a soft
gelatinous substance composed of translucent
globules, which, however, are not perceptibly
joined together ; so that there is in this instance
nothing of that fibrous structure, which is the
great characteristic of the cellular membrane in
the human body and in the higher orders of ani- _
mals. In the semifluid and jelly-like body ofthe
Polypifera and of some of the Acalephe, there
is merely a pulpy substance, which, although it
may exhibit a distinct digestive cavity, and even —
tubes communicating with this, yet no mus-
cular tissue has hitherto been discovered. In
these animals, however, rapid movements are
seen in the cilia; and the tentacula, when pre-
sent, together with the entire body, are capable
of spontaneous motion ; it is evident, then, i
these and other instances, that if, as is g
rally supposed, there be an absence of m
the cellular tissue must be endowed with a pro-
perty totally wanting in that substance x
exists in the higher animals. When it is con-

CELLULAR TISSUE.

sidered how little is known testi the real
structure of the Infusoria, Zoophytes, &c., and
when the numerous discoveries which have of
late years been made in these and much higher
animals, of parts whose existence was formerly
doubted or denied, are recollected, we shall be
inclined to think that there are special organs of
motion provided ; for it would be in direct oppo-
sition to the simple but constant laws observed
in the animal creation, were the organic tis-
sue, entitled the cellular, to acquire in the lower
classes a power of contraction, which in the
higher it does not possess, and which property
is the endowment of a totally distinct system of
organs, namely, the muscles. Whichsoever of
these opinions be correct, there is no doubt that
in the least perfect animals, a soft and gelatinous
matter, analogous to the cellular tissue, and
loaded with fluids, greatly predominates. As
we advance in the scale, it is found that organ-
ized substances of a diversified character are
developed in the nidus afforded by this cellular
texture, the proportion of which to the other
structures becomes thus diminished.

Morsipd CONDITIONS OF THE CELLULAR
TIssurE.—As the cellular membrane is so in-
timately united with all other organs, it is very
liable to be involved in diseases commencing
in these parts; but morbid action also very
frequently arises primarily in this tissue. It
is subject to—1, inflammation, acute and chro-
nic, circumscribed and diffused; to the effects
of inflammation, thickening and induration,
suppuration, ulceration, and mortification; 2, in-
filtration of blood, serum, air, and occasionally
of other substances, as urine; 3, induration,
occurring in new-born infants; 4, morbid
growths, such as fibrous productions, cysts,
melanosis, scirrhus, vascular sarcoma ; 5, foreign
bodies; 6, preternatural increase or hypertro-
phy, and degeneration, or atrophy.

I. Inrtammartion.—This tissue is very fre-
quently affected by inflammation, which may
either present itself under the form of a distinct
affection, as when it attacks the subcutaneous
cellular membrane especially, or it may occur
as a part of some other disease, as when inflam-
mation of the parenchyma of the lungs, liver,
&e., spreads to the cellular tissue in which this
substance is universally involved.

a. Acute circumscribed inflammation, or phleg-
mon.—The anatomical characters of this form
of inflammation of the cellular substance are
essentially the same in whatever part of the
body it may arise, either in the subcutaneous
tissue, or in that part which penetrates into the
interior of the various organs ; it will, therefore,
be proper to trace the effects of it in a general
manner. |

1. Congestion of the bloodvessels—The ef-
fects of irritation on the capillary vessels, in
which the phenomena of inflammation are prin-
cipally observed, may be beautifully seen with
the aid of a sufficiently powerful microscope in
the transparent membrane of the frog’s foot.
After having familiarized the eye by watch-
ing the circulation for a short time, we shall
“find that the first effect produced by the appli-
cation of an irritant is a distinct and evident

513

acceleration of the blood’s motion. I have not
been able to satisfy myself of that diminution
of the calibre of the vessels which is said by
some observers to accompany this acceleration.
If the irritation be repeated, or if its power in
the first instance were considerable, it will be
seen after a certain time that the capillary ves-
sels become dilated, that the blood moves more
slowly, and often that it oscillates and circulates
apparently with difficulty ; its constituent parts
become less distinct, the particles being crowded
together. If the effects of the irritation now
subside, the dilated vessels contract and recover
their proper calibre, the blood again moves
more freely, and the circulation regains its
natural state; but, on the contrary, if the mor-
bid action still persists, the membrane begins
to grow opaque, either in consequence of the
engorgement of the vessels, or, as it has appeared
to me, from an extravasation of one or other of
the constituents of the blood; or, lastly, the
circulation altogether ceases, the vessels are
further enlarged, the blood is stagnant, and is
evidently deteriorated in quality, and the colour
becoming deeper and deeper, is at length per-
fectly brown, or even black. This is the order
in which the phenomena in the derangement of
the circulation occur ; and although they have
been more particularly studied in microscopical
observations on the lower animals, yet many of
them are daily to be observed in the human
hody during the progress of inflammation.
Whilst the inflammatory action is confined to
the first of the above stages, in which there is
merely a preternatural excitement of the circu-
lation, it may be arrested and put an end to
without any further morbid change; and this
may even happen in the second stage, where
the blood, although accumulated and retarded
in its motion, still circulates in its proper ves-
sels. This speedy termination of the disease
has been called by the French writers deli-
tescence.

2. Effusion—When the bloodvessels are
greatly congested and dilated, it usually hap-
pens that a part of their contents escapes, and the
cellular tissue becomes loaded with coagulable
lymph, more or less tinged with blood accord-
ing to the vascularity of the affected part, pro-
ducing that condition which has been called
red induration. ‘This substance, by agglutina-
ting together the fibres and layers, causes the
hardness which is so perceptible on pressing
the diseased part. At the same time that this
solid deposition takes place in the centre, it is
found that the circumference of the inflamed
part is soft and edematous, in consequence of
the cells being distended with a fluid which
appears to be the serum of the blood. Although
the cellular tissue is rendered more firm to the
touch by the effusion of lymph, yet, as happens
in the other organized structures of the body
when attacked by acute inflammation, the co-
hesion of its fibres is diminished, and it is, con-
sequently, more easily torn than in its natural
state, and its elasticity is also greatly impaired.
The preceding changes may be very beautifully
observed in the progress of pneumonia, when
the substance of the lungs is passing into that

514

condition which is called red hepatization. I
have in my possession a specimen of com-
mencing hepatization, taken from a lung in
another portion of which that change was quite
complete. In this preparation a portion of the
pulmonary tissue is of a reddish brown colour,
and evidently infiltrated with a solid substance,
consisting, it may be presumed, of fibrine
mixed with the colouring matter of the blood.
The manner in which this deposition took place
in the cellular tissue of the organ is distinctly
seen, the reddish colour being gradually shaded
off till it is lost in the healthy structure.

It sometimes happens that the morbid action
now ceases, and that by a process of absorption
the interstitial effused matter is removed, so as
slowly to restore the part to its proper condition :
this is the termination of inflammation to which
the term resolution is applied.

3. Suppuration.—It usually happens in acute
inflammation of the cellular tissue, that after
the lapse of a certain period, a softening takes

lace towards the centre of the circumscribed
hain in consequence of the diminution of
cohesion above described gradually increasing,
and of the deposition of purulent matter. It is
not certain how the pusis formed in the first in-
stance; several modern pathologists, especially
in France, imagine that the lymph and serum
which were previously effused experience a
change by which they are converted into pus,
a theory which is rendered probable by the
physical properties of pus so nearly resembling
those of the blood: according to other autho-
rities, pus is a proper secretion derived from
the neighbouring arteries. I believe that in the
beginning the purulent matter results from
changes in the effused matters; but that when
suppuration is fully established, the pus is
poured out or secreted from the bloodvessels.
In the commencement the pus is observed in
the cells of the tissue, under the form of whitish
spots; subsequently the walls of these inter-
stices are broken down by the softening alluded
to, and the purulent matter is collected together
so as to constitute an abscess, which is sur-
rounded by a rather dense layer of cellular
tissue, still retaining the characters of inflam-
mation. This layer constitutes the sac of the
abscess, and presents at first a rough and reddish
surface; but it soon happens that the walls
acquire a greater firmness, and that the surface
of the sac assumes very much the appearance
of a mucous membrane.

4. Ulceration.—When an abscess has thus
been formed, the cellular tissue intervening be-
tween it and the external surface of the body, is
removed by the action of the absorbents. This
process, which is always preceded by inflam-
mation, and accompanied by suppuration, is
distinguished from various other morbid actions
of the absorbents by the term of ulceration.
Other instances of ulceration occurring in the
cellular tissue might be adduced; ex. gr.
the separation of the slough in carbuncle, after
extravasation of urine, &c.

5. Mortification.—If the inflammatory action
be sufficiently intense, it causes the destruction
of the vitality of the part affected, and pro-

CELLULAR TISSUE.

Fete “Tn the most acute re of hyper-
emia,* the circulation of the blood is sus-
pended, and if this stagnation be prolonged so
as to become complete, the parts being gorged
with blood that is no longer renewed, and —
which, therefore, soon becomes unfitted to s
port nutrition and life, must necessarily peri
and in this manner gangrene is produced, as in _
the experiments performed by Dr. Hastings. —
In these cases the black colour announces the
stagnation of the blood, and this stagnation
being prolonged, must of necessity lead to
gangrene. Such, in my opinion, is the manner
in which the species of gangrene usually attri-
buted to excess of inflammation, is produced.”
M. Gendrin has ascertained by dissection that
some of the vessels are filled with coagulated
blood ; whilst others are actually ruptured, and
allow their contents to escape. The cessation
of the circulation has for a long time been
remarked as the most striking character of mor-
tification; in fact, that cessation, in whatever
manner it may have been induced, whether by
inflammation, by continued pressure, by the
application of tight bandages to a limb, &c., is
in the great majority of instances the imme-
diate cause of mortification. The consequence
of this loss of vital action is, that the natural
properties and appearance of the cellular tissue
are destroyed ; the affected part becomes dis-
coloured, usually assuming a black or ash-
coloured appearance; the proper texture is
lost, and the part is infiltrated with a dark
sanious fluid, and is subsequently converted
into a shapeless mass of pulpy substance, which
is cold to the touch, and extremely offensive
to the smell, owing to the gases which are
generated by putrefaction: in fact, the part is
dead, and presents the usual appearances caused
by the decomposition of animal matter, con-
joined with those which result from the pre-
vious effects produced in the circulation by the
inflammatory action, especially the engorge-
ment of the bloodvessels. These are the changes
induced in the cellular substance when it is
attacked by humid, or, as it has been called,
inflammatory gangrene. In dry gangrene, on
the contrary, the black and discoloured part
shrivels up, and does not undergo the same
changes which are produced by the decom
sition of a texture which is loaded with fluids.
b. Chronic inflammation.—As we find that
in phlegmon there is a great tendency to the
formation of pus, so in chronic inflammation
there is usually a deposition of solid matter,
which produces more or less of induration and
enlargement. This deposition seems almost in —
every instance to occur in the cellular tissue, —
either where it is interstitial, or where it pene-
trates into the interior of the several organs.
This is observed among other parts in chronic
* This is a generalterm employed by M. Andral
to designate the increased quantity of blood which
is contained in the capillary vessels of any ©
without any reference to the cause which pro:
the accumulation. In the passage above qu
se. which "es!

he is speaking of acute hyperemia,
nymous with acute inflammation. +

CELLULAR TISSUE.

inflammation of glands, as the testis, mamma,
liver, tonsil, &c.; in the lymphatic glands,
especially in scrofulous persons ; in various dis-

eases of the joints; in the hard swellings so often »

seen in scrofula, gout, and rheumatism; in
imperfectly cured erysipelas, pellagra, and ele-
phantiasis; in the callous edges of old ulcers ;
in the uterus, labia pudendi, and prepuce of
the penis ; and, according to Otto,* in that pe-
culiar induration of the cellular tissue which
occurs in new-born children. This distin-
guished pathologist, in common with many
other continental writers, attributes phlegma-
sia dolens to the same cause. ‘The incorrect-
ness of this opinion has been demonstrated by
the researches of Dance, Arnott, Lee,and others.
(See Vern.)

The great induration often induced by long-
continued chronic inflammation was called by
the older writers scirrhus; and even in the
present day most of the French pathologists
apply that term to the hardness thus induced,
as well as to the malignant disease, to indicate
which English practitioners restrict the word.

The substances that are effused into the cel-
lular tissue in chronic inflammation are various,
according to the part attacked, the circum-
stances of the disease, constitution, &c. It
generally consists of a whitish or greyish matter,
of a lardaceous, homogeneous appearance, caus-
ing whatis called by modern pathologists, white
induration ; and sometimes it is of a yellowish, or
even bluish colour. It is doubtful whether this
substance consists of the fibrine or albumen of
the blood, or of some newly formed material. In
scrofulous individuals the deposition consists of
the well-known caseous matter, so characteristic
of the strumous diathesis; lastly, this form of
inflammation, especially in strumous constitu-
tions, often leads to the formation of chronic
abscess, the contents of which, as Gendrin,
Mayo, and others have observed, do not, how-
ever, consist of true pus, but of serum generally
mixed with a flakey matter, or even tinged with
blood.

_ ¢. Spreading or diffuse inflammation.—The
cellular tissue, constituting in all parts of the
body an uninterrupted secreting surface, is sub-
ject to spreading inflammation, which, from the
extent of the parts implicated, the disorganiza-
tion induced, and the alarming character of the
attendant constitutional disturbance, must be
regarded as one of the most formidable diseases
to which the human hody is subject. In what-
ever manner this disease originates, whether
from poisoned wounds, from phlegmonous ery-
sipelas, from external injury, or from any other
cause, it progressively and rapidly attacks a
large extent of the cellular tissue, often invading
an entire limb, or even a considerable part of
the trunk. In examining parts thus affected
after death, they are found to be variously
altered, according to the duration of the dis-
ease and the order in which they became in-
volved ; in those which are most recently im-
plicated, the cellular substance is merely cede-

* Compend, of Pathol. Anat. by South, vol. i.
p- 91.

515

matous, containing a large quantity of limpid
or reddish-coloured serum, which readily flows
out on making an incision, and which after-
wards acquires more consistence, and becomes
more deeply coloured. In the subsequent
stages, pus, sometimes pure, sometimes dis-
coloured, is effused: the matter is at first con-
tained in the cells, which are gorged with a
whitish semifluid matter, but afterwards depéts
of matter take place in the disorganized tissue ;
there being, however, no proper cyst, owing to
the want of that barrier of lymph which is
effused in common phlegmon. These abscesses
are often numerous, but insulated and distinct
from each other: at other times they occupy a
great extent, and contain a large quantity of pus,
often mixed with shreds of mortified membrane.
In the more severe forms of this affection the
natural organization is in some places totally
destroyed, and the cellular substance, from the
effects of gangrene, is converted into a greyish
or dark-coloured slough.

These changes are not confined to the sub-
cutaneous membrane, in which, however, they
are principally observed, but are seen in the
cellular sheaths of the muscles, and even in the
processes which separate their different fasciculi.
The muscles themselves, under these circum-
stances, partake in the disorganization, and lose
their proper colour.

The progress of this formidable disease would
seem to shew that an acrid and irritating hu-
mour is effused into the cellular substance,
where it rapidly causes suppuration and slough-
ing, in the same manner as when urine is ex-
travasated into the perineum and scrotum.
That a vitiated state of the blood is often pro-
duced is a now well-known fact, and such a
condition appears to be induced in the disease
under consideration, either in consequence of
the introduction of a poison into the system, as
from the bite of a venomous serpent, or from a
deterioration of the constitution, as in draymen,
coal-porters, and others, who in large towns con-
sume enormous quantities of fermented liquors ;
or, lastly, from both these causes combined, as
from punctures received in dissection by indi-
viduals who at the time are in an indifferent
state of health.

II. Inrrirratron, or effusion.—The escape
of various fluids from their proper receptacles
into the cellular tissue is of extremely frequent
occurrence.

a. Blood.—This is effused either as a conse-
quence of external violence acting on the arte-
ries and veins, or from an internal cause, of
which the nature is more obscure. When the
hemorrhage is extensive, the surrounding tissue
is unable to resist the progress of the blood,
and the infiltration becomes of considerable ex-
tent. Itis by effusions of this kind that ecchy-
moses, false aneurisms, &c. are formed.

b. Serum.—A very common morbid change
is the infiltration of a thin watery fluid into
this tissue, consisting of an accumulation of
the serum naturally exhaled into its cells. The
effused fluid, apparently owing to its contain-
ing a larger proportion of albumen than usual,
is occasionally of a more viscid nature, so as

516

to escape but imperfectly on a puncture bein
made ; and in other cases, as in the diffused
swelling so often occurring in bad constitutions
after serious local injury, compound fractures,
poisoned wounds, &ec. the effused fluid is of
an acrid character. The effusion is often
restricted to a particular region, (@dema ;)
at other times it is more extensive, and
may even occur in all parts of the body
(anasarca). In all instances in which effusion
takes place, it ought to be regarded sag as
an effect, resulting from some previous change
in the vessels of the cellular tissue, which
stands in the relation of a cause. This change
consists, I believe, in the great majority of
cases, if not in all, in a preternatural con-
gestion of the bloodvessels, which may be
induced by inflammation, debility, mechanical
obstruction to the free return of the venous
blood, or the suspension of any of the great
secretions of the body.

c. Air.—Emphysema, in its usual form,
arises from an unnatural communication being
formed between some part of the air-passages
and the cellular tissue (traumatic emphysema ) :
it is thus an occasional consequence of fracture
of the ribs, in which the neighbouring portion
of the lung is lacerated ; of penetrating wounds
of the chest; of rupture of the air-cells by
violent exertions; of ulceration of the air-
cells ; of rupture of the membrane of the larynx,
and even of the lachrymal sac and windpipe,
and of fractures in the vicinity of the frontal
sinuses, causing a laceration of their mucous
membrane. Emphysema has been likewise
known to arise spontaneously, the air appear-
ing to be secreted from the bloodvessels ; and
it is also a frequent attendant on gangrene, in
which case the effused air is the result of the
decomposition of the fluids previously col-
lected.

d. Urine.—Effusion of urine may arise from
a wound or ulceration of any of the organs
through which the urine passes ; usually, how-
ever, it is a consequence of an injury of the
bladder or urethra. The accident particularly
demands notice on account of the destructive
effects which result from it. These effects are
extensive mortification of the cellular tissue,
and, in a somewhat less degree, of the skin,
followed by profuse suppuration, attended with
constitutional symptoms of so serious a nature
as often to cause the death of the patient.

III. Inpuration.—Induration occurs as a
special disease in new-born infants, and in a
large proportion of those who are attacked,
there is a fatal termination from the sixth
to the thirtieth day; in very severe cases,
and in infants prematurely born, death may
take place in two, three, or four days. Some
idea of the mortality in this disease may be
formed from the following facts: in the
Foundling Hospital in Paris, the mortality of
late years has been one in three ; out of twenty-
seven cases occurring in 1809, at La Charité
in Berlin, only two were saved; in fifteen
cases seen by Lobstein, four recovered.

The disease is very prevalent in the large
foundling hospitals on the continent, as many

CELLULAR TISSUE.

‘country, where, fortunately for humanity, no

as 240 cases occurring in one year in the Hos-
pice des Enfans Trouvés of Paris, out of |
5392 received into the institution. In this _

such establishments exist, and where conse-
quently new-born infants are but rarely deserted _
by the mother, the disease is very rare. Dr.
Copland states that he has not met with an
instance of it in the Queen’s Lying-in Hospital,
and that even in the Infirmary for Children,
such cases are very rarely presented. I have
made inquiries of several very extensive prac-
titioners of midwifery, some of whom are con-
nected with public institutions, and they have
very rarely or never seen the disease. .

The parts which are attacked, usually the
legs, hands, and face, are more or less swollen,
hard, and rigid to the touch; and the skin
assumes a red or violet colour in consequence
of the respiration being imperfectly performed.
The affection consists of an cedematous state of
the cellular tissue, the areole being loaded
with a concrete albuminous matter and a sero-
Sanguineous fluid, which oozes out when a
section is made and quickly coagulates ; it is
this infiltration that is the cause of the peculiar
hardness, for according to M. Billard, who has
carefully investigated the characters of the dis-
ease, the cellular fibres and layers preserve all
their flexibility, and present no signs of having
undergone any organic change. According to
M. Chevreul, in this disease the serum of the
blood contains an abundant quantity of a matter
distinct from fibrin, but which spontaneously
coagulates ; this substance is perfectly identical
with the material to which the cellular tissue
Owes its apparent induration.

The history of this disease, and the results
obtained by dissection, prove that venous con-
gestion is a very constant morbid appearance ;
and it is a question that has not hitherto been
decided, how far this congestion is the exciting
cause of the disease.

IV. Morsip crowrns. — These are of
very common occurrence and of very various
characters; some consisting of the trans-
formation of the cellular membrane into other
tissues, the fibrous and osseous for example;
whilst others are entirely new productions, and
occasionally prove of a malignant nature, such
as cysts, vascular sarcoma, scirrhus, melanosis,
&c. We do not often meet with bony or
fibrous formations in the common cellular
structure, although I have occasionally seen
growths with these characters. From an ex-
amination of many specimens, I am induced
to believe that the ossific deposits not unfre-
quently observed in connection with the fibrous
and serous membranes, as the dura mater,
pleura, &c. are formed in the cellular tissue of —
these structures. a

V.—ForEIGN BODIES are sometimes intro- —
duced into the cellular tissue from without,
such as bullets, needles, &c. Certain para-
sitic animals, the origin and characters of
which are very obscure, are also occasionally —
met with in the substance of the human body,
and especially in the cellular tissue. At the
present day it is generally admitted that hy-

=

CEPHALOPODA.

datids are bodies endowed with vitality, the
most common species of which is the acepha-
locyst ; another species is the cysticercus cel-
lulosus. The filaria medinensis, or guinea-
worm, is another parasitic animal which has
been seen in the human body.

Lastly, the cellular tissue may vary in the
degree of its consistence, colour, &c.; and
owing to some derangement in the function of
nutrition, it may present a preternatural in-
crease or a wasting of its substance: (hyper-
trophy or atrophy.)

BIBLIOGRAPHY. — Bordeu, Recherches sur le
tissu muq., in his works by Richerand. W. Hunter,
in Med. Obs. and Inq. vol. ii. p.17. Haller,
Elementa Physiolog. The systems of Portal,
Bichat, Meckel, Beclard, Craigie, and ;Grainger,
Blandin & Beclard, Add. a l’Anat. Gén. de Bichat.
Dict. de Méd. art. Cell. Tissue. M. Edwards,
Recherches microsc. sur la struct. intime des tiss.
organ, des anim. Hodgkin, Annals of Phil. Aug.
1827. The systems of physiology by Blumenbach,
Hajendie, Bostock, and Tiedemann. Fodéra, Journ.
de Phys. t. iii. p. 35. Lindley, Introd. to botany.
Roget, in Bridgwater Treat., Anim. and Veget.
Phys. Grant's Lectures, Lancet, 1833, 34, vol. ii.
Pp. 357. De Blainville, De Vorganis. des animaux.
flunter, Treatise on the blood, &c. Thomson’s
Lectures on inflammation. James, Observations
on inflammation. Portal, Cours d’anat. méd. t. ii.
t.v. Lawrence, Lectures on inflammation, in Lancet,
vol. i. 1829, 30. Hastings, Treatise on the lungs,
p. 57. Billard, Traité des mal. des enf. nouv.-nés,
p- 169. Gendrin, Hist. anat. des inflam. t.i. p. 14;
t. ii. 358. Andral, Précis d’anat. pathol. Otto, Com-

endium of pathological anatomy, by South. Cop-
Cds Dict. of Pract. Med. art. Cellular Tissue. Wells,
Transactions of a Society for Improvement of Medi-
cal and Chirurgical Knowledge, vol. iii. Breschet,
Recher. sur les hydrop. actives, &c. Paris, 1812.
Blackall, Obs. on dropsy, London, 1813. Aber-
crombie, in Edin. Med. and Sur. Journal, vol. xiv.
Ayre’s Researches into the nature and treatment of
dropsy, p. let seq. Cyclop. of Pract. Med. art.
Anasarca. Dict. de Méd. et de Chir. Prat. art.
Acephalocystes, Anasarque, Emphyséme, Entozoaires,
In, tion. Mayo, Outlines of human patho-
logy. Lobstein, Traité d’anat. pathol. p. 201.
Dunean, in Trans, of Med. Chir. Soc. Edin. vol. i.

(R. D. Grainger.)

CEPHALOPODA—(xsQaan, caput, sous,
pes); Eng. Cephalopods; Fr. Céphalopodes ;
Germ. Kopffusslern, Blackfische, Tinten-fische ;
Ital. Seppie, Polpi. Syn. Maraxia, Aristotle ;
Mollia, Pliny; the genera Nautilus, Argo-
nauta, and Sepia, Linné ; Octopodia, Schneider ;
Mollusca brachiata, Poli; Mollusca Cephalo-
poda, Cuvier; Cephalopoda, Lamarck, Leach ;
Brachiocephala, Céphalophores, De Blainville ;
Pterygia, Latreille, (including the Pteropoda
of Cuvier); Antliobrachionophora, Gray.

Definition.—A class of Molluscous Inver-
tebrate animals in which the head (A, figs.
206, 209,) is situated between the trunk (B)
and the feet (C), or principal organs of loco-
motion.

Characters of the Class —The trunk or body
is thick and soft; varying in form from a
sphere, to a flattened ellipse, or elongated
cylinder; sometimes protected by a shell,
sometimes naked; consisting of a membranous
or muscular sheath or mantle, with a transverse

517

anterior®™ aperture (a, figs. 206, et seq.) and
containing the respiratory, circulating, gene-
rative, and principal digestive viscera: the
mantle sometimes supports a pair of fins (6,
Jigs. 207, 208, 209,) and, in the naked species,
lodges in its substance the rudiments of a shell.

The head is distinct from the trunk, of large
size, and of a rounded figure ; it contains the
organs of sense, mastication,and deglutition, and
gives off from its anterior circumference or exter-
nal surface, a number of fleshy processes which
encircle and more or less conceal the mouth.

These processes, by some naturalists termed
the feet, but which we prefer to call, with Poli,
the arms, are either very numerous, short, and
hollow, containing each a long, slender retrac-
tile tentacle (figs. 205, 213); or they are eight
(figs. 206, 210), or ten (figs. 207, 208),
in number, solid, supporting on their internal
surface numerous suckers (antlia, acetabula ) ;
and being more or less elongated and flexible in
every direction, they act as powerful organs of
adhesion, prehension, and locomotion.

The eyes are a single pair, of large size,
varying in relative perfection of structure ac-
cording to the locomotive powers of the spe-
cies, and either pedunculated or sessile.

The mouth is anterior, and situated at the
bottom of the conical cavity formed by the
base of the feet ; it is provided with two horny
or calcareous jaws, shaped like the mandibles
of a Parrot, playing vertically on each other,
and inclosing a large fleshy tongue, which is
armed with recurved horny spines.

The branchi@ are concealed within the man-
tle, and are symmetrical in size, form, and posi-
tion. The systemic circulation is aided by a
muscular ventricle.

The infundibulum, (2, figs. 206, 208,) or pas-
sage through which the respiratory currents and
the excrements are discharged, is a muscular
tube, situated at the anterior part of the neck,
shaped like an inverted funnel, with the pipe
projecting from the visceral cavity, and directed
forwards.

The sexual organs are separate and exist in.
distinct individuals; but whether impregnation
takes place by copulation or after the ova are
excluded is not determined ; the former is most
probable.

All the species are aquatic and marine.

Division of the Class into Orders—The
type of organization which characterizes the
Cephalopods, and of which the preceding is a
general outline, presents two principal modi-
fications, according to which the class is di-
vided into two orders.

* Throughout the present article the terms of
aspect and position relate to that in which the
animal is represented in fig.206. The shell covers
the posterior part of the body, the arms are anterior
and directed forwards; the letters A, B, C, are
along the dorsal or upper surface, the letter i is
beneath the ventral or lower surface.

t A third order of Cephalopods (the Cellulacea
of De Blainville) has been proposed to include an
extensive series of minute polythalamous shells, of
exquisite beauty in their form and sculpture, which
differ from the camerated shells of our Tetrabran-
chiate order in the absence of a siphon, but which

518

In the first of these, which is most
closely allied to the Gasteropodous Mol-
lusks, the branchie are four in number,
and the order is therefore termed Tetra-
branchiata : in the higher division, which
approaches nearest to the Vertebrate ani-
mals, the branchie are two in number,
and the order is called Dibranchiata.

Order I. TETRABRANCHIATA.
Syn. Polythalamacés, Blainville; Sipho-
nifera, D’Orbigny ; minus the Spirulide
and Belemnitide.

The Tetrabranchiate Cephalopods, of
which the Pearly Nautilus (fig. 205)
may be regarded
as the type, are
provided with a
large external uni-
valve shell, sym-
metrical in form
like the body of
the animal which
it protects,
straight, or con-
voluted on a ver-
tical plane, and
divided by a se-
ries of partitions
(a, a) into nume-
rous chambers
(6,6), of which the
last-formed (b’) is
the largest, and alone contains the body of the
animal: a dilatable and contractile tube (c, c)
is continued from the posterior part of the

M. D’Orbigny believes to be constructed by mol-
luscous animals of a grade of organization which
entitles them to rank with the Cephalopodous class.
For this group of animals M. De Haan has pro-
posed the name of Asiphonoidea ; but M. D’Orbigny,
observing that the chambers of their shells com-
municate together by means of one or more fora-
mina, has substituted the positive term Foraminifera,
and they are placed by Cuvier at the end of the
Cephalopodous class under that denomination in
the last edition of the Régne Animal.

Strong evidence has, however, been recently ad-
duced to prove that these minute shells owe their
existence to animals which have no pretensions to
rank with the Cephalopods ; but before we give the
account of M. Dujardin, who is the author of this
view, we shall first quote M. D’Orbigny’s own
description of the animal of the shells, the struc-
ture of which he has so ably studied and so happily
demonstrated by means of enlarged models.

«< The Cephalopods of the Foraminiferous Order
have a bursiform body, in the posterior part of
which the shell is lodged; the body of the animal
sometimes presents a great size compared to that
of the head, to which it is occasionally subservient
as a means of protection, entirely surrounding it
in the anterior folds of the skin. The head is
small, scarcely, if at all, distinct from the body,
terminated by numerous tentacles forming many
rows around the mouth, which is central. The
animal seems to adhere very slightly to the shell;
it rapidly passes into a state of decomposition after
death, when the slightest touch is sufficient to
detach it from the shell, in which nothing is left
but a coloured liquid which fills all its chambers.
The food of these animals consists of different species
of Polyps.”

M, De Blainville, however, states, in the Ap-
pendix to his Manuel de Malacologie, page 649,
that the animal of one of the microscopic genera con-

CEPHALOPODA.

The Pearly Nautilus, Nautilus Pompilius, Linn. 4

o AWE
Q ii
l

\
"

animal through all the partitions and cham-
bers of the shell; but the attachment of
the shell to the body is effected by means of

tained in his order Cellulacea, viz. Miliola, has no
relation whatever in its structure to a Cephalopod,
or Cryptodibranche. And more recently M, Dujar-
din has read a memoir, entitled ‘ Sur les Symplee-
toméres, ou pretendus Cephalopodes microscopiques,’
in which the results of numerous and apparently
careful observations on the soft parts of different
genera of the animals in question are directly op-
posed to those of M. D’Orbigny.

M. Dujardin carefully studied the Miliole, Vortici-
aliz, Rotaliz, Truncatuline, Cristellarie, Mellonia,
&c. in the recent and living state; and found that
the shell*was not internal, and that the animal, which
is absolutely deprived of organs of locomotion and
even of respiration, is composed of a succession of
joints or lobes, which go on increasing successively,
and enveloping each other. The only period when
the soft parts of the animal are visible externally,
is when a new joint is produced which has not com-
pleted the formation of its chamber. On breakin
the shell, the composition of the animal is foun
to be as simple as in the Planarie or Hydre, or any
other animals of the Acrite sub-kingdom; and on
dissolving the shell by means of a mixture of
alcohol and very weak nitric acid, the entire body
is obtained, which is formed of a succession of
articulations, occupying all the chambers; and
presenting different aspects in different genera,
which accord with the peculiarities of the shell.

From these observations it necessarily follows —
that the Foraminifera of M. D’Orbigny cannot be
arranged with the Cephalopods, or even placed in
the Molluscous Series. M. Dujardin, therefore,
proposes to consider them as a distinct class of
Invertebrata, under the name of 85)
and until further and better evidence be adduced
to the contrary, we shall regard these minute ani- —
mals as having only, in the form and structure of —
their shells, a remote analogical relation to the
Cephalopods. ‘ae

—

CEPHALOPODA.

two strong lateral muscles (d*), which are in-
serted into the walls of the last chamber.
The numerous hollow arms (e, e) and retrac-
tile tentacles (f, f), mentioned in the general
characters of the class are peculiar to this order,
and the head is further provided with a large
ligamento-muscular plate, or flattened disc, (g,)
which, besides acting as a defence to the open-
ing of the shell, serves also, in all probability,
as an organ for creeping along the ground,
like the foot in the Gasteropods. There are no
fins or analogous organs for swimming.

The jaws of the Tetrabranchiata are strength-
ened by a dense, exterior, calcareous coating,
and have thick dentated margins.

The eyes are pedunculated (h, fig. 205) and
of a simple structure.

There is no organ of hearing.

The gills are four in number, and without
branchial hearts.

The circulating system is provided with but
one ventricle, which is systemic or propels
arterial blood.

There is no ink-bag.

The inferior parietes of the funnel (i, fig.
205) are divided longitudinally.

Order II. DIBRANCHIATA. Syn. Cryp-
todibranches, Blainv.; Acetabulifera, D’Orb. ;
plus the Spirulide and Belemnitide.

In the Dibranchiate Cephalopods one genus
alone ( Argonauta, fig. 206) has been hitherto
found in which the body is protected by an

(p=

The Paper Nautilus or Argonaut,
Argonauta Argo, Linn.

external shell (a); but this, though symme-
trical, and convoluted on a vertical plane,
consists of one simple chamber, or is ‘ mono-
thalamous,’ and does not adhere to the body
of its Cephalopodous occupant, either by a
hydraulic pipe or lateral muscles. All the
other genera of the Dibranchiate Order are
naked; but they are provided either with an
internal siphoniferous polythalamous shell,+ or
the remains of a shell are found in various stages

* The letter is placed on the portion of
broken shell which still adhered to one of the
lateral muscles in the specimen taken by Mr. Geo.
Bennett, in the New Hebrides Islands. See Pl. 1,
Memoir on the Pearly Nautilus, 4to. 1832.

+ This is the case in the Families Spirulide and
Belemnitide ; the terms Polythalamacea or Sipho-
nifera, therefore, do not distinguish the preceding

a fossil state, in

519

of degradation lodged in the substance of the
dorsal part of the mantle.

The arms of the Dibranchiata are, properly
speaking, eight in number, (c, 1, 2, 3, 4,
fiz.2065 to which, in many genera, two longer
tentacles (d, d, figs. 207, 208) are superadded.
Both kinds of prehensile organs are provided
with acetabula, or suctorious discs for adhesion ;
and hence the order has been termed Acetabu-
lifera.

The jaws are horny, and their margins tren-
chant.

The eyes are sessile, (e, e, fig. 207,) and of a
more perfect structure.

The organ of hearing is distinctly developed.

The gills never exceed two in number; but
the branchial circulation is aided by two mus-
cular ventricles, situated one at the base of each
gill; hence there are three distinct hearts in
this order.

There is an organ for secreting and expelling
an inky fluid, used as a means of concealment.

The parietes of the funnel are entire, (i,
figs. 206, 208.)

Subdivision of the Orders.—In the ancient
periods of the globe the Tetrabranchiate Cepha-
lopods appear to have abounded in every sea ; one
genus only, however, viz. the Nautilus, appears
to have escaped the influences which have ren-
dered extinct the rest of this once extensive order.
Their chambered shells are found, generally in
all the regions of the globe,

and at every elevation, charac-
terizing the strata of the se-
condary formation. In some
places they occur in such pro-
digious numbers that the rocks
appear to be composed almost
exclusively of their remains.

Some of these fossil shells
testify the immense size to
which their animal construc-
tors must have attained: the
shells called ‘ Cornua Am-
monis,’ which were formed by
Cephalopods resembling the
Nautilus, have been found
measuring four or five feet in
diameter; some of the straight
chambered shells, called ‘ Or-
thoceratites,’ exceed four feet
in length; other species again appear not to
have surpassed the size of a grain of rice.

As the consideration of these remains, of
which the Tetrabranchiate division of Cepha-
lopods is almost exclusively composed, would
necessarily oblige us to exceed the limits allot-
ted to this article, we shall here subjoin merely
the characters of the two families into which
they naturally resolve themselves, and to which
their distribution appears to be limited.

Fe 4

or Tetrabranchiate Order, nor indicate any cha-
racters peculiar to that group, or which are of ordi-
nal importance: and in other Molluscous classes
it may be observed that modifications of the shell
fail to afford indications of the primary divisions,
which are uniformly based, as inthe present arrange-
ment of Cephalopods, on the modifications of the
respiratory system.

520

Fam.1. NAUTILIDA, Nautilites.

Animal, organized as. described in the
character of the order.

Shell external; spiral, or straight; septa
smooth, and simple; the last chamber
the largest, and containing the animal:
siphon central, or marginal and in-
ternal.

Ex. Genera Nautilus, Lamarck; Cly-
menes, Munster; Campulites, Des-
hayes; Lituites, Breyn; Orthoceratites,
Breyn. .

Fam.2. AMMONITIDZ, Ammonites,

Snake-stones.

Animal unknown, presumed to resemble
the Nautilus.

Shell external; spiral or straight; septa
sinuous, and with lobated margins;
the last chamber the largest and lodg-
ing the animal: siphon central, or mar-
ginal and external.

Ev. Genera Baculites, Lamarck; Ha-
mites, Parkinson; Scaphites, Parkin-
son; Ammonites, Bruguitre; Turru-
lites, Lamarck.

The Dibranchiate Order of Cephalopods
also had its representatives in the seas of the
ancient world, as the shells called Belemnites,
or thunder-stones, the fossil shells of the Sepiz
discovered by Cuvier, and the horny rings of
the acetabula found by Buckland in the fossil
feeces of Ichthyosauri, sufficiently testify; but
our knowledge of this order is chiefly founded
on observation of existing species. These are
extremely numerous; they frequent the seas
of every clime, from the ice-bound shores of
Boothia Felix to the open main, and floating
Sargasso or gulf-weed of the Equator; theyseem,
however, to be most abundant in temperate lati-
tudes. Many species frequent the coasts, creep-
ing among the rocks and stones at the bottom ;
others are pelagic, swimming well, and are
found in the ocean at a great distance from
land.

The Dibranchiata present great variety of
size, and although the bulk of the gigantic
species has been undoubtedly exaggerated, yet
the organization of this order is favourable
to the attainment of dimensions beyond those
presented by the individuals of any other
group of Invertebrate animals. The remains
of the large Uncinated Calamary caught by
Banks and Solander in the Southern Ocean,
ati of which are still preserved in the

unterian Museum, and the fragment of the
Cephalopod weighing one hundred pounds,
taken by the French naturalists in the Atlantic
Ocean under the line, and preserved in the
Museum of the Garden of Plants at Paris,
afford indubitable testimony of the formidable
size to which some individuals of this order
attain.

The species included in the higher divi-
sion of Cephalopods very naturally resolve
themselves into those which possess the eight
ordinary arms, forming the tribe Octopoda ;
and into those which have the additional pair
of elongated tentacles, forming the tribe De-
capoda. :

CEPHALOPODA. — . : eS =

The Decapods are further characterized by
having a pair of fins attached to the mantle;
by having the funnel either adherent at the —
antero-lateral parts of its base, and withoutan =
internal valve, or articulated at the same part =
by two ball-and-socket joints to the mantle, and
previa with a valve internally at its apex ;

y having fleshy appendages to the branchial
hearts, and glandular appendages to the biliary
ducts; by having generally a single oviduct,
with detached superadded glands; and, lastly,
by the shell or its rudiment being single, mesial,
and dorsal.

The Decapodous tribe is that which is most
nearly allied to the Tetrabranchiate Order. This
affinity is not only indicated by the additional
number of external arms, and the frequent de-
velopment of an internal circular series of eight
short labial tentacles, but by several internal
characters; as the single oviduct and detached
glands for secreting the nidamentum ; the valve
of the funnel; the laminated rudiment of a
chambered shell in the Cuttle-fish, and the fully
developed chambered and siphoniferous shell
of the Belemnites and Spirula. The observa-
tions of Peron and Lamarck having proved
that the animal of the Spirula possesses eight
short arms and two long tentacles, all provided
with acetabula, like the Sepia, we regard it
as the type of the first family of the Decapo-
dous Tribe, or that which immediately succeeds
the Tetrabranchiata.

Tribe DECAPODA.

Fam. 1. SPIRULID.

Animal, corresponding in external form
to the Decapodous type; internal or-
ganization unknown, presumed to be
Dibranchiate.

Shell partly internal; cylindrical, multilo-
cular, discoid; the whorls separated ;
septa transverse, concave next the out-
let, and with regular intervals.

Siphon marginal and internal, uninter-
rupted.

Genus Sp1rvuxa, Lam.

The character of the family is also that of
the single genus of which it is at present
composed.

Ex. Spirula Australis, Lam.

Fam. 2. BELEMNITIDA, Belemnites,

Thunder-stones.

Animal unknown.*

Shell internal, composed of an external
calcareous sheath formed by a succes-
sion of hollow cones, the exterior being
the largest; of an internal horny sheath,
also of a conical form, containing at its
apex a chambered shell, the septa of

* As it is certain that the animals of this family _
of extinct Cephalopods possessed the ink-bag, they —
must consequently have been enveloped by a mus-
cular mantle ; and we may, therefore, infer that
they resembled the Dibranchiates in their locomo-
tive and respiratory organs, and consequently in
the general plan of their organization. In
structure and position of their siphoniferous c;
rated shell they are intermediate to Spirula
a 0 and as the animal of Spirula is proved
a Decapod, the probability is very strong
animal of the Belemnite was of the same type.

CEPHALOPODA. 521

which are concave externally and perfo-
rated by a marginal and ventral siphon.

Genus Betemnites, Lamarck.*

Fam. 3. SEPIADA, Cuttle-fishes.

Animal, body oblong, depressed, with two
narrow lateral fins extending its whole
length.

Shell internal, lodged in a sac in the back
part of the mantle, composed of an ex-
ternal calcareous apex or mucro, of a
succession of calcareous lamine with
intervening spaces filled with air, and
supported by columns, but not perfo-
rated by a siphon, and an internal horny
layer, corresponding to the anterior
horny sheath of the Belemnites.

Genus Sspra, Cuv.

The character of the family is also that of
the single genus at present composing
it; we may, however, add under this
head that the mantle is free at its an-
terior margin; and that the acetabula
are supported by horny hoops with the
margin entire, or very minutely denti-
culated.

Ex. Sepia officinalis, Linn. the common
Cuttle-fish. ¢ Fig. 207.)

Fig. 207.

Fam. 4. TEUTHIDZ,* Calamaries.

Animal, body sometimes oblong and de-
pressed, generally elongated and cylin-
drica! ; with a pair of fins varying in their
relative size and position, but generally
broad, shorter than the body,and terminal.

Shell internal, rudimental, in the form of
athin, straight, elongated, horny lamina;
encysted in the substance of the dorsal
aspect of the mantle.

A. Funnel with an internal valve, and arti-
culated at its base to two venrtro-lateral
cartilaginous prominences of the mantle.

Genus Sepioreutuis, Blainville.

Body oval, flattened, with narrow lateral
fins, extending its whole length; ante-
rior margin of the mantle unattached.
Horny hoops of the acetabula with den-
ticulated margins. Gladius, or rudi-
mental shell, long and wide.

Ex. Sepioteuthis loliginiformis, Ruppel.

Genus Loxico, Cuvier.

Body elongated, cylindrical, provided with
a pair of rhomboidal or triangular fins,
shorter than the body, and terminal,
their apices generally converging to a
point, and united to the end of the man-
tle; anterior margin of the mantle free.
Horny hoops of the acetabula denticu-
lated. Gladius long and narrow.

Ex. Loligo vulgaris, Cuv. the common
Calamary or Pen-fish. ( Fig. 208.)

Fig. 208.
oP

The Calamary, Loligo vulgaris, Cuv.

* From the term tev$o¢ applied by Aristotle to
the ten-armed Malakia with an internal horny
plate or gladius.

* Also the fossil genera, Actinocamaz, Miller ;
Pseudobelus, Blainvyille.

VOL, I. 2M

522

CEPHALOPODA.

Genus Onycuorevrutis, Lichtenstein.
Body and fins as in the genus Loligo ;
ventro-lateral cartilages of the mantle
long and narrow; horny hoops of the
tentacular, and sometimes of the bra-
chial, acetabula produced into the form
of hooks or claws. (Fig. 215.) Gla-
dius long, broadest in the middle.

Genus Rossta, Owen. Body short and
rounded ; cephalic margin of the mantle
free; fins advanced, short, circular, ses-
sile, distant and subdorsal. Gladius
short and narrow.

Ex. Rossia palpebrosa, Owen.

Genus Septota, Leach. Body rounded,
short; anterior margin of the mantle
adherent to the back of the head ; fins
advanced, circular, short, subpeduncu-
late, distant and subdorsal. Gladius
short and narrow.

Ex. Sepiola Rondeletii, Leach.

B. Funnel unprovided with an internal

Loligopsis Veranii.

valve, and adherent at the antero-lateral

parts of its base to the mantle. aah

Genus Louicopsis, Lamarck. ay

Body long and cylindrical, terminated bya
pairof conjoined largeround fins, forming
generally a circular disc ; anterior border
of the mantle adherent to the back part
of the head for a small extent. Tenta-
cula very long and slender, (frequently
mutilated.) Gladius long, narrowest in
the middle, dilated posteriorly.

Ex. Loligopsis Veranti, Férussac. ( Fig. —

209;
shell.)
Genus Crancuta, Leach. Body elon-
gated, sacciform; anterior margin of
the mantle adherent to the back of the
head. Fins short, rounded, subpedun-
culate, approximate, dorsal, and sub-
terminal. Gladius long and narrow.
Ex. Cranchia scabra, Leach.

the gladius or rudimental

Tribe OCTOPODA. The Dibranchiate
Fig. 209.

CEPHALOPODA. 523

2g sale besides wanting the long tentacula,
are also characterized by the absence of man-
tle-fins, and consequently are limited to retro-
grade progression while swimming ; their ace-
tabula are sessile and unarmed ; they have two
oviducts, but without detached glands for secre-
ting a nidamentum.
Family TESTACEA.

Body oblong, rounded; mantle adhering
posteriorly to the head ; first, or dorsal
pairs of arms dilated and membranous
at the extremity; (c, 1, jig. 206.)
Funnel without a valve, but articulated
at its base by two ball-and-socket joints
to the inner sides of the mantle. Bran-
chial hearts with fleshy appendages.
No internal horny or testaceous rudi-
ments; but an external monothalamous,
symmetrical shell, containing, but not
attached to, the body of the animal;
which also deposits its eggs in the cavity
of the shell.

Genus Anconavuta, Linneus. On the
supposition that the shell is parasitically
occupied by the Cephalopod, but formed
by some other mollusk, some natu-
ralists limit the above generic title to
the shell, and call the Cephalopod
Ocythoé.* We shall, however, con-

tinue to apply the term Argonauta to the
Cephalopod in question, asthe evidence,

Fig. 210.

* Shonld the above suspicion be proved to be
well founded, we conceive that it would be more
appropriate to retain the term Argonauta, in order

Genus Ocrorus, Leach.

The Poulp, Octopus culgaris, Cuv.

though strong, is not conclusive of its
arasitic nature. The character of the
ainily is also that of the Genus.

Ex. Argonauta Argo, Linn. (fig. 206.)
Genus Belerophon, founded on the fossil

remains of a shell resembling in family
characters that of the Argonauta.

Ex. Belerophon apertus, Sowerby.
Family NUDA.
Body generally rounded, mantle broadly

continuous with the back of the head.
Arms connected at the base by a broad
web : first pair elongated, and gradually
narrowing to a point. Funnel without
an internal valve or external joints;
branchial hearts without fleshy appen-
dages; biliary ducts without follicular
appendages. Shell represented by two
short rudimental styles, encysted in the
dorso-lateral parts of the mantle.

The arms pro-
vided with a double alternate series of
sessile acetabula.

Ex. Octopus vulgaris, Cuv. the Poulp or

Preke, (fig. 210, in which this species
is represented in the act of creeping on |
the shore ; its body being carried verti-
cally in the reverse position with the
head downwards; its back being turned
to the spectator, towards whom it is
supposed to be advancing.)

to designate the Cephalopod which navigates the
frail bark; and revert to the original name of
Cymbium for the shell, which was applied to it by

2m 2

524

Genus Etrepone, Leach. The arms pro-
vided with a single series of sessile
acetabula.

Ex. Eledone cirrosa, Leach.

Internal cartilaginous parts, or Endo-
skeleton.—In the Gasteropodous Mollusks the
cerebral or supra-cesophageal ganglions are pro-
tected by a dense membrane which has been
compared to a dura mater, hut which may be
regarded with more propriety as representing
the membranous condition of the skull in the
embryo of the vertebrate animal; and which,
in fact, assumes a cartilaginous texture in some
of the higher organized Pectinibranchiata,
forming in them the unquestionable rudiment
of a true internal skeleton.

In the present class a thick cranial cartilage
not only protects the cephalic masses of the
nervous system; but it is enlarged and extended
in different directions, so as to afford a basis of
attachment to the principal muscular masses of
the body: thus fulfilling the second important
function of an internal skeleton.

In the Nautilus it consists of one principal
eartilage, (fig. 211,) which is situated on the

: ventral aspect of the
cesophagus ; two pro-
cesses (a a) extend
from the posterior or
dorsal angles on each
side of the esophagus
as far as the optic gan-
glions. A deep semi-
circular groove (6)
extends along the an-
terior part of these
processes for the lodg-
ment of the optic
ganglions and the an-
terior nervous collar
surrounding the ceso-
phagus. Two other
processes (c c) arise
from the ventral angles
of the cartilage and
give support to the sides of the base of the
funnel. A middle process is extended some
way between the two great muscles which are
inserted into the shell. The central part or
body of the cartilage (d) is excavated for the
reception of the venous blood returned from
the head and funnel, and from this sinus the
great dorsal vein commences.

In the Dibranchiate Cephalopods the inter-
nal cartilaginous skeleton consists of a greater

Internal Cartilage or
Skeleton of the Nautilus.

Gualtieri, when he first separated it generically
from the Chambered Nautilus. In either case, as
the grounds for constituting the new family of Oc-
topoda now proposed are derived from important
organic differences, as manifested in the structure
of the funnel and the branchial hearts, the claims
of the Cephalopod to form the type of such a group
would not be destroyed by the proof of the shell
forming no part of its structure. We cannot, how-
ever, retain both the genera Argonauta and Ocy-
thoé, as in the Familles Naturelles du Régne Animal
-of Latreille, p. 168; since, if the shell in question
be not secreted by the Cephalopod, its analogy to
that of the Carinaria would indicate its real con-
stractor to bélong to the Heteropodous Mollusks.

CEPHALOPODA.

number of pieces, and has a more imp oe
share in the organization and functions of the _

animal. We shall describe it principally as it _
exists in the Cuttle-fish (Sepia Officinalis).

The cranial cartilage (A, fig. 212) is no |
longer limited in its position to the under side
of the esophagus, but completely surrounds —
that tube, which, together with the mferior sali-
vary ducts, and the cephalic branches of the
aorta, traverses a narrow passage in the centre.
It is expanded above into a cavity, which en-
closes and protects the brain; while, below the
cesophagus, the dense cartilage is excavated to
form the two vestibular cavities of the organ
of hearing; at the sides it is developed into
broad and thick concave processes, which form
the back part of the orbits.

In the subjoined figure A is the cranial car-
tilage as seen from above :—

a is the superior part which protects the brain.

b, 6, are the two large optic foramina.

c, c, the posterior and inferior thick ex-
panded orbital process. .

d, d, the thin and long anterior and inferior __
cartilage which supports the eye-ball, and is
analogous to the cartilaginous eye pedicle of
the Rays and Sharks: these processes are com-
pared by Meckel to the superior maxillz ; they
do not exist in the Octopods, and are compa-
ratively much smaller in the Calamaries than
in the Cuttle-fish.

e, the anterior aperture of the canal through
which the cesophagus passes.

J; a process, continued from the anterior
part of the cranial cartilage, which expands
into a broad transverse plate, witha slight con-
cavity directed forwards, and gives attachment
to the muscles of the arms: this cartilage
Meckel compares to the lower jaw, but the
analogy is not more satisfactory than in the
preceding instance.

The infundibular or nuchal cartilage (B),
which is a process of the cranial cartilage in
the Nautilus, is in the Dibranchiates, and es-
pecially the Cuttle-fish, a distinct piece, of
large size, and of a flattened triangular figure,
situated above the base of the funnel, with its
apex directed forwards and its posterior angles
turned backwards; it has a moderately deep
furrow along the middle of its upper surface.
In the Sagittated Calamary this important car-
tilage consists of three portions, a middle elon-
gated one, having on its dorsal surface a mesial
longitudinal! groove, and two lateral longitudinal
ridges which are adapted to a corresponding —
ridge and two grooves in the under part of the —
sheath of the gladius, which sheath here assumes —
a dense cartilaginous consistence: from the an=
terior extremity of the middle nuchal cartilage
two flattened cartilages extend outwards and
backwards, and then curve slightly inwe
These correspond to the dilated base of the ¢a
lage in the Sepia, protect the great lateral nerves
of the mantle, and give origin to the latera
muscles which are perforated by the nerves. —

On each side of the base of the funne
there is a smooth oblong articular cavity wl
is formed by a distinct cartilage (C); it is
adapted to receive a corresponding cartilagi.

was. se S/O

CEPHALOPODA. 525

Skeleton of the Cuttle-fish.

nous prominence arising from the inner sur-
face of the sides of the mantle. This pro-
minence in the Sepia is of an oval shape ; but
in the Teuthide it forms a narrow, elongated,
cartilaginous ridge, and is adapted to a cor-
responding groove at the sides of the funnel.
In the Calamary the ridge is of the same size
with the groove ; but in the Onychoteuthis the
ridge or antero-lateral cartilage commences at

_ the anterior margin of the mantle, and extends
_ downwards some way below the termination of

the infundibular groove. Rathké* discovered

in the corresponding part of the mantle of the

-* Mémoires de l’Acad. Imp. des Sciences de
Petersbourgh, tom. ii. pt. 1 et 2, p. 154,

Loligopsis, viz. on either side and towards
the ventral aspect, a thick, opaline, elongated
cartilage, extending longitudinally for more
than half the length of the mantle, and sup-
porting a series of wart-like processes. These
ateral tuberculated cartilages in Loligopsis we
regard as corresponding to the lateral ridges in
the Calamaries and Onychoteuthis above-men-
tioned ; but in the Loligopsis they are not arti-
culated with the sides of the funnel, which are
otherwise attached to the mantle. In all the
Decapods, however, this pair of cartilages on
the ventro-lateral aspects of the mantle is more
or less developed.

In the Sepia a longitudinal cartilage is
situated on the ventral aspect of the liver.
The long lateral fins are, in the same genus,
each supported by a narrow, flattened, elon-
gated, cartilaginous plate (D, D, fig. 212);
pointed at its anterior extremity, obliquely
truncate behind; smooth and gently concave
internally (g), but traversed by an_ irre-
gular longitudinal ridge (A) on its external
surface. These cartilages form the points of
attachment to the powerful muscles of the
lateral fins. From the dorsal ridge of each
cartilage a number of close-set fibro-cartila-
ginous lamine extend at right angles to the
cartilage to near the margin of the fin, with
their plane in the direction of the axis of the
body: they alternate with the strata of mus-
cular fibres, resembling the rays which support
the fins of fishes.

The analogy of this structure to the cartila-
ginous basis of the great pectoral fin of the Ray
is so close and satisfactory that we can scarcely
hesitate to acknowledge the locomotive appen-
dages of the mantle in the Decapodous Cepha-
lopods as representatives of the pectoral fins of
fishes, and consequently of the anterior extre-
mity of the vertebrated animal. As they are
not, however, fixed to a vertebral column, their
situation is not constant, being sometimes, as
in Rossia, situated towards the anterior part of
the body; sometimes, as in Loligo, placed at
the posterior extremity ; just as we perceive the
ventral fins of Fishes shifting their position, in
consequence of a similar want of connexion,
so as to occupy, in some species, a position
more anterior even than the pectoral fins, with-
out losing their essential character, as the ana-
logues of the posterior extremities.

The cartilages of the fins correspond in length
to the parts which they support, and are con-
daiienily much longer in the Cuttle-fish than
in the Calamaries; in the Octopods they are
entirely wanting.

Locomotive System.— The organs of loco-
motion in the Cephalopods are of two kinds,
one consisting of appendages developed from
the head ; the other of rudimental fin-like ex-
tremities developed from the trunk ; the latter
organs are confined, as we have seen, to the
Decapodous genera of the higher-or Dibran-
chiate Order.

The cephalic processes, which are called
digitations, arms, feet, tentacles, and pedun-
cles, have no real homology with the loco-
motive extremities of the Vertebrata; to these
they are analogous only, inasmuch as they

526

havea similarrelation of subserviency to the loco-
motive and prehensile faculties of the animal.

Among the Vertebrates traces of organs corre-
sponding to these cephalic feet are met with
principally in the class of Fishes, in the form
of tentacles developed from the lips; and
Schultze, a learned German Naturalist,* has
indicated the close affinity which the Cyclo-
stomous Fishes bear, in this respect, to the
Cephalopods; in one genus, viz. Gastro-
branchus, or Myzine, eight free filaments are
extended forwards from the circumference of
the funnel-shaped orifice of the mouth, repre-
senting the eight ordinary arms of the Cepha-
lopoda Dibranchiata, but arrested in their de-
velopment because of the pre-
ponderating size of the caudal
extremity of the body, which
now forms the sole locomotive
organ. The expanded sucker
anterior to the jaws of the
Lamprey may, in like manner,
be considered to represent the
united bases of the cephalic
feet of the class under consi-
deration.

In the Nautilus the cephalic
organs of prehension and loco-
motion consist of slender sub-
cylindrical annulated tentacles,
which are sheathed and retrac-
tile, (fig. 213,) like those of
some of theGasteropodousMol-
lusks, as Doris, Thethys, and
Tritonia. Here, however, they
astonish the observer by their
unexampled number, _ sur-
rounding the mouth in suc-
cessive series, and amounting
to little short of a hundred.
These tentaclesare divided into
three kinds, according to their
Situation, viz. ‘ brachial or
digital,’ § ophthalmic,’ and
‘ labial:’ the latter being
again subdivided into ‘ ex-
ternal’ and ¢ internal.’

The brachial tentacles are
forty in number, and are sup-
ported by short conical trihe-
dral hollow processes or digita-
tions, (e, e, fig. 205,) of which
the two superior or dorsal ones

Fig. 213.

CEPHALOPODA.

=:

Digitation and

i

are conjoined and dilated into
a muscular disk covering the

I ,
whole upper part of the head, Seika vllens
(CS; g, fig. 205;) the remaining pilius.

thirty-eight are disposed ir-

regularly, nineteen on either side, one over-
lapping another, and all directed forwards, con-
verging towards the orifice of the oral cavity,
in which the jaws and mouth are concealed.
Thelongest of these digitations, when its free
extremity only is measured, does not equal one
inch; but externally they appear longer, be-
cause they adhere for some way to the sides of
the head. The digitations present no trace of

sotartee Archiv. fiir Physiologie, B. iv. p. 338,

acetabula or suckers, but are at the
extremity by a canal (a, a, fig. 213,) which is
continued far into the substance of the head to
near the cerebral ring; the tentacle (b) which
is lodged in this canal, is consequently longer
than the digitation from which it is protruded.
The labial tentacles, forty-eight in number,
extend from orifices situated on the anterior
margins of four broad flattened processes,
arising from the inner surface of the oral
sheath opposite the base of the mandibles.
Two of these processes (a, a, fig. 219) are
superior, posterior, and external in situation ;
the other two, (6, 6, fig. 219,) which are smaller,
are inferior, anterior, and more immediately
embrace the jaws, and they are connected to-
gether bya lamellated organ (c, fig.219), after-
wards to be described. Each of these ‘labial’
processes is pierced by twelve canals contain-
ing the tentacles in question: they differ from
the digital tentacles only in relative size, and
in being of a softer and more delicate texture.
The ophthalmic tentacles seem more ex-
pressly designed as instruments of sensation ;
they do not possess the strength requisite for :
prehensile purposes, and are not situated con- .
veniently for locomotive actions; they are four
in number, and project laterally one before and
one behind each eye, involuntarily reminding
the observer of the antenne in Crustacea, &c. ‘
At first sight they seem annulated like the
brachial and labial tentacles ; but upon a closer |
:
3

examination, they are found to consist of a num-
ber of flattened circular disks closely packed
upon a lateral stem, a structure which is sin-
gularly analogous to that of the antenne of
the Lamellicorn Beetles. In this respect, how-
ever, the Pearly Nautilus does not stand alone
in the Molluscous series, the retractile tentacula
of the Doris present a very similar structure.

The fibres of the dense musculo-ligamentous
sheath (d, d, fig. 219), which incloses the man-
dibles and supports the eyes and digital pro-
cesses, arise from the whole of the anterior
and outer part of the cartilaginous skeleton
above described. They were so densely in-
terwoven in the specimen we dissected as to
preclude the possibility of ascertaining their
exact course or arrangement.

The large lateral muscles of the funnel come
off principally from the infundibular processes
of the internal cartilage. There are also two
small round and distinct muscles designed to
draw the funnel closer to the head, they pass
to their insertion through canals excavated in
the sides of the funnel.

The fleshy masses which proceed backwards —
from the posterior part of the skeleton are the —
two great muscles (b, b, fig. 231,) which attach —
the Nautilus to its shell. These are insertec
by obliquely truncated flattened extremities
into a layer of horny substance which is_
closely adherent to the inner surface of the
sides of the last chamber of the shell at a little
distance from the septum forming its base:
where, in recent specimens, these impressions —
are always to be plainly seen. The part which —
passes through the perforations of the septa 1s_
not a muscular or tendinous chord, as has been
conjectured, but a weak membranous tube,

“a

J
oi \
Be
S.
a
y

vr | 9 i
= i a

CEPHALOPODA.

which can lend but a feeble assistance in main-
taining the shell in its natural position.

The mantle of the Nautilus is very thin and
membranous, excepting at its free margin,
where it is provided with longitudinal mus-
cular fibres for its retraction, and a thin exter-
nal stratum of transverse fibres, for the closing
of its anterior aperture, during the expulsion
of the respiratory currents.

The large mandibles (a, 6, fig. 217; e, f,
Jig. 219,) are mperel upona fleshy substance
(g, fig. 217), and moved by appropriate mus-
cles. The fringed lip (c, fig. 217) which sur-
rounds them is provided with a longitudinal
stratum of fibres for its retraction, and an exte-
rior orbicular sphincter at its anterior margin.
The whole buccal apparatus is attached to the
cartilaginous skeleton by four strong retractor
muscles, two above (h, A, fig. 217, 219), and
two below (i, 2, fig. 217), and its base is sur-
rounded by a transverse stratum of muscular
fibres (i, fig. 219) continued from the external
labial processes, across the upper or dorsal
aspect of the jaws, which, by the contraction
of these, fibres, are protruded outwards.

The tongue (fig.236) is a large complex
muscular organ, the extremity of which is
retracted by two pair of long slender muscles
(d) arising from the dense membrane closing
the lower part of the mouth; a third pair of
muscles (b) given off from the posterior mar-
gins of the lower mandible are inserted into
the anterior extremity of the horny lingual
rasp hereafter to be described. Other internal
muscular parts will be mentioned in the de-
scription of the viscera to which they relate.

e muscular system of the Dibranchiate
Cephalopods, like their internal skeleton, is
much more elaborately developed than in the
inferior order of which the Nautilus is the
type: but the same plan may be observed to go-
vern the disposition of all the principal masses.

A hollow cone of muscular fibres is attached
by a truncated apex to the anterior margin of
the cephalic cartilage, or to processes deve-
loped therefrom, in order to afford these fibres
an increased surface of origin. The fibres are
interlaced, one with another, in a close and
compact manner as the cone expands to
form the cavity containing the fleshy mass
of mouth; and at the anterior extremity of

the mouth they are continued forwards and
Separate into eight distinct portions, which
form the arms.

These organs are developed in a kind of
inverse proportion to the body, being generally,
as Aristotle* twice takes occasion to observe,
longest in the short round-bodied Octopi or
Poulps, and shortest in the long-bodied Cala-
maries, Sepie, &c. in which the two elongated
retractile tentacles (d, fig. 207, 208, 209) are
superadded, by way of compensation. These
latter organs are rarely continued from the
muscular cone inclosing the apparatus of the
mouth, but arise from the cephalic cartilage,
close together, internal to the origins of the

* De Historia Animalium, (Ed, Schneider, Lip-
Siz,) libhiv. ©1.8&9, ©

527

ventral pair of brachia; they proceed at first
outwards to a large membranous cavity situated
anterior to the eyes, and thence emerge between
the third and fourth arms on either side.

The acetabula or suckers are disposed along
the whole extent of the inner surface of the
ordinary arms, but are generally confined to
the extremities of the tentacles, where they are
closely aggregated on the inner aspect.

Of the difference between the arms and
tentacles Aristotle was well aware, and ac-
cordingly, with his usual exactness, he applies
to them distinct epithets: médu¢ piv oby dura
fxet xal robtevg dinorUAcug mavTa MARY Byoc yévos
moruTadwy. “Ia Exovew al re onmiat xal al revdides
wat of 20001 dv0 mpoBoruidac peanpac Em” axpwy tpa-
xYtnta Eyoioas Dustvroy.* << All (mollia) have
eight feet, provided with a double series of
suckers, except in one genus of Polypi.t The
Sepie, Teuthides, and Teuthi,t have, besides,
two long proboscides, the extremities of which
are beset with a double series of suckers.”
Pliny gives, after the Stagyrite, the fol-
lowing notice of their functions, “ Sepie et
Loligini pedes duo ex his longissimi et asperi,
quibus ad ora admovent cibos, et in fluctibus
se, velut ancoris, stabiliunt.” German authors
generally term the ordinary feet, ‘arms,’ (arme, )
and the tentacles ‘ seizers,’ (fangarme. )

In the Cephalopods which have only the
eight normal feet, these present many vari-
ations; and, although they are generally re-
markable for their length, yet in some species,
as the Octopus brevipes, they are extremely
short, resembling the digital processes of the
Nautilus. In Octopus Eylais, the first or
dorsal pair is alone developed so as to serve
as a locomotive organ, and the animal mustcrawl
along the ground by means of this pair only.

In most Octopods the first pair of feet is the
longest. In Octopus Aranea, in which the
feet apparently present the maximum of de-
velopment, the dorsal feet are ten times, and
the ventral ones five times, the length of the
body. Besides their superior length the dorsal
feet present other peculiarities in this family
of Cephalopods. In the genus Argonauta
(fig. 206, ¢1,) they are provided with expanded
membranes, the fabled use of which has af-
forded a beautiful subject for poetic imagery
in all ages; but similar appendages occur in
Octopus violaceus, and in Octopus velifer, in
which both the first and second pairs of feet
support broad and thin membranes at their
extremities. Now neither of these species in-
habit a shell, in which the expanded mem-
branes could be used to waft the animal along
the surface of the ocean, as has been said or
sung of the Argonaut from Aristotle to Cuvier,
from Callimachus to Byron. The physiologist,
in contemplating the structure of the velated
arms, is compelled to disallow them the power
of being maintained erect and expanded to

* Ibid. lib. iv. c. 1. 4.

+ The genus Eledone of Aristotle, the eight feet of
which have only a single series of suckers uponeach,

¢ Species of Loligo or Calamaries, supposed to
be the Loligo vulgarts and Loligo media of modern
naturalists.

528

meet the breeze. What their real function
may be is still to be determined; but the re-
moval of the erroneous impressions entertained
on this subject is the first step towards the at-
tainment of the truth.

In our common Octopus, and most other
species of this genus, the feet are connected
together for some distance beyond the oral
sheath by membranes and museles which form
a circular fin. This is their sole locomotive
organ when swimming; and by its powerful
contraction they are driven through the water
with a quick retrograde motion. In a species
which we have recently described* (Octopus
semipalmatus ) the fin is extended only between
the four dorsal arms: a structure which must
occasion a characteristic difference in its mode
of swimming.

The disposition of the muscles of the web-
like fin is as follows. There are two transverse
layers of fibres, the external arises from a white
line extending along the back-part of each
foot; the internal from the sides of the same
feet between the attachments of the suckers.
These two strong muscular bands are con-
nected together as they pass from arm to arm
in the middle of the webs, and decussate one
another, so that the external become internal
and vice versa. Within these a thin layer of
longitudinal fibres extends to the free margin
of the webs; and there is also a layer of ob-
lique longitudinal fibres externally, which arise
from the white line at the middle of each foot:
these fibres are shown at (kK, k, fig. 216,) the
transverse fibres at /, 4.

In the Cephalopods which possess the re-
tractile peduncles, the ordinary arms are gene-
rally short, and the first or dorsal pair are
commonly exceeded in length by the second ;
sometimes, indeed, as in the species of Loli-
gopsis, of which the figure is subjoined,
(fig. 209,) they go on progressively increasing
in length to the ventral or fourth pair, which
here resembles in its great development the
arms of the Octopods. The peduncles are
always longer, and more slender than the arms;
they exhibit these characters in the highest
degree in the genus Loligopsis, in which they
are frequently mutilated and lost; but the
examination of the nerve proceeding to the
mutilated stump sufficiently attests, in such
cases, the importance of the organ of which
this animal has been accidentally deprived.
The tentacles serve to seize a prey which may
be beyond the reach of the ordinary feet, and
also to act as anchors to moor the Cepha-
lopod in safety during the agitations of a
stormy sea.

Each arm is perforated near the centre of its
axis for the lodgment of its nerve (a, fig. 214)
and artery (b); and upon making a transverse
section of the arm, these are seen to be lodged
in a quadrangular or rhomboidal space (c) of a
light colour and apparently soft homogeneous
texture, but in which a few radiating fibres may
be discerned. This part is surrounded by four

* See Proceedings of the Zoological Society for
March, 1836,

CEPHALOPODA.

Section of an Arm and Suckers of a Poulp.

groups of transverse striz forming as many seg-
ments of a circle, external to which there are
two thin circular strata of fibres. On making
a longitudinal section of the part the striated
segments are seen to consist of longitudinal
muscular fibres, and of the surrounding strata,
the fibres of the internal are longitudinal, and
those of the external transverse. It is easy to
conceive that, like the tongue in Mammalia,
the arms thus organized may be lengthened,
shortened, curved, and bent in all conceivable
directions.

The acetabula or suckers with which the in-
ternal surface of the arms of the Dibranchiates }
are provided, vary in relative position, in size, |
in structure, and in mode of attachment, not
only in different species, but in different arms
in the same individual, and sometimes in diffe-
rent parts of the same arm. ‘Thus in the pe-
dunclesof Loligopsis Veranii,the suckers on the
long cylindrical stem are sessile, while those on
the expanded extremity are supported on long
peduncles; and another remarkable instance
will presently be mentioned of suckers having
different structures for different functions in the
same arm.

In the Dibranchiate genera which are charac-
terized by a soft thin skin, as the Argonaut, ~
Octopus, and Eledone, the suckers are soft
and unarmed ; in those genera which have a
hard and thick skin, as the Calamary and
Onychoteuthis, cuticular appendages are deve-
loped in the cavities of the suckers. ~

An excellent description of the unarmed —
acetabulum as it exists in the genus Octopus, is
given by Dr. Roget. | —

The circumference of the disc is raised bya
soft and tumid margin (e, fig. 214); a series —
of long slender folds of membrane (f'), cover- —
ing corresponding fasciculi of muscular fibres
converge from the circumference towards
centre of the sucker, at a short distance fie
which they leave a circular aperture (g):
opens into a cavity (h), which widens
descends, and contains a cone of soft substa

See ee eS er ee.

’ CEPHALOPODA.

(i) rising from the bottom of the cavity, like
the piston of a syringe. When the sucker is
applied to a surface for the purpose of adhe-
sion, the piston, having previously been raised,
so as to fill the cavity, is retracted, and a
vacuum produced, which may be still further
increased by the retraction of the plicated cen-
tral portion of the dise. So perfect is the me-
chanism for effecting this mode of adhesion,
that in the living Cephalopod, “ while the mus-
cular fibres continue contracted, it is easier to
tear away the substance of the limb than to
release it from its attachments: and even in the
dead animal the suckers retain a considerable
power of adhesion.” *

Still there are circumstances in which even
this remarkable apparatus would be insufficient
to enable the Ceplalopod to fulfil all the offices
in the economy of nature for which it was
created; and in those species which have to
contend with the agile, slippery, and mucus-
clad fishes, more powerful organs of prehension
are superadded to the suckers.

In the Calamary the base of the piston is
inclosed by a horny hoop, the outer and ante-
rior margin of which is developed into a series
of sharp-pointed curved teeth. These can be
firmly pressed into the flesh of a struggling
prey by the contraction of the surrounding
transverse fibres; and can be withdrawn by the
action of the retractor fibres of the piston. Let
the reader picture to himself the projecting
margin of the horny hoop developed into a
long, curved, sharp-pointed claw, and these
weapons clustered at the expanded terminations
of the tentacles, and arranged in a double alter-
nate series along the whole internal surface of
the eight muscular feet, and he will have some
idea of the formidable nature of the carnivo-
rous Onychoteuthis.

Banks and Solander, in Cook’s first voyage,
found the dead carcase of a gigantic species
of this kind floating in the sea, between
Cape Horn and the Polynesian Islands, in
latitude 30° 44’ S. longitude 110° 33’ W.
It was surrounded by aquatic birds, which
were feeding on its remains. From the parts
of this specimen, which are still preserved in
the Hunterian Collection, and which have
always strongly excited the attention of natu-
ralists, it must have measured at least six feet
from the end of the tail to the end of the tenta-
cles. The natives of the Polynesian Islands,
who dive for shell-fish, have a well-founded
dread and abhorrence of these formidable
Cephalopods, and one cannot feel surprised that
their fears should have perhaps exaggerated
their dimensions and destructive attributes.

We cannot quit this part of our subject
without noticing a structure which adds greatly
to the prehensile powers of the uncinated
Calamaries: at the extremities of the long ten-
tacles, besides the uncinated acetabula, a cluster
of small simple unarmed suckers may be ob-
served at the base of the expanded part. When
these latter suckers are applied to one another,

* Roget, Bridgewater Treatise, i. p. 260. See

also Baker, An Account of the Sea-Polypus, Phi-
losoph. Trans. vol. 1. p. 777.

529

the tentacles are firmly locked together at that
part, and the united strength of both the elon-
gated peduncles can be applied to drag towards
the mouth any resisting object which has been
grappled by the terminal hooks. There is
no mechanical contrivance which surpasses
this structure: art has remotely imitated it in
the fabrication of the obstetrical forceps, in
which either blade can be used separately, or,
by the interlocking of a temporary joint, be
made to act in combination. (See fig. 215,
; where d marks
the stemsof the
peduncles, e
the parts joined
together by the
mutual apposi-
tion of the un-
armed suckers,
J the terminal
expanded por-
tions bearing
the hooks.)
The great
muscular coni-
cal basis which
gives origin to
the feet is at-
tached, as be-
fore mention-
ed, to the an-
terior part of
the annular
cephalic carti-
lage: it is also
provided with
distinct fasci-
culi of muscu-
lar fibres, which
connect it to
the mantle and
to other parts
of the body.
In the Octo-
pus a great pro-
portion of these
fibresarise from
the _ posterior
part ofthe man-
tle, and, di-
verging as they
pass forwards,
spread over the
posterior and
lateral parts of
the head, rece-
ding at the sides
to leave a space
for the eye;
they then di-
vide into five
bundles, each
of which again
subdivides into
two, which are
lastly inserted
into the sides
of the six dorsal and lateral feet. (See a, a,

fig. 216.)

Fig. 215.

Sy }
\ it

Arms and Tentacles of an
Onychoteuthis.

530

Muscles of the Poulp, Octopus Vulgaris.

Fasciculi of muscular fibres (6, b, 216,) are
continued from the ventral pair of feet and the
back part of the cranium, across the base of
the funnel to the muscular septum, which
divides longitudinally the branchial cavity.
Other fibres descend to join the muscular tunic
enveloping the liver and esophagus (d, d) ;
but the fibres of this part rise principally from
the posterior part of the cephalic cartilage.

The septum of the branchial chamber above-
mentioned is the strongest and most complete
in the genus Eledone, where, with the excep-
tion of a very small part of its posterior termi-
nation, it is muscular throughout.* In the
Poulp, in which this septum (c, fig. 216) is
well described by Cuvier as the “ bride ante-
rieure qui lie la bourse a la masse viscerale,”
a greater proportion of the posterior part is
membranous. In the Argonauta the muscular
part of the septum is reduced to two narrow
and delicate fasciculi, which arise from the
back part of the cranial cartilage, descend ob-
liquely forwards, iutercept the termination of
the rectum and ink-duct, to which they serve
as a sphincter, and then expand in the vertical
direction to be inserted along the middle line
of the inner surface of the anterior part of the
mantle. A membrane is continued from the
upper margin of the muscular septum to within

* See Carus’ original figure, Vergleich. Zooto-
mie, pl. iv. fig. 4, g, in Octopus ( Eledona) Mos-
chatus.

CEPHALOPODA. ‘

a short distance of the anterior margin of the
mantle, and another from the lower margin ex-
tends downwards, and terminates opposite the
base of the gills; the branchial chambers in-
tercommunicate both above and _ below this
septum. In Sepiola the muscles corresponding
to the “ bride anterieure” of the Octopus are
developed in the same degree as in the Argo-
naut, arising not from the back of the funnel,
but from the cranial cartilage; the septum is
completed below by membrane. In the Cuttle-
fishes and Calamaries these muscles and the

septum of the branchial chamber are wanting.
The muscular parietes of ‘the funnel are
formed by an external longitudinal (e) and an
internal transverse (f.) layer, strengthened by the
insertion of the extrinsic muscles of this part.
The principal of these are the lateral muscles
(g, fig. 216,) which in the Poulp take their
origin from the capsules of two small styles,
hereafter to be described, at the sides of the
mantle, and are inserted into the sides of the
funnel and the muscular tunic of the liver. In
the Cuttle-fishes and Caiamaries they are at-
tached to the cartilaginous articular cavity at :
the sides of the base of the funnel, as well as |
to its fleshy parietes. |
These muscles serve to retract and depress |
the funnel; it is raised and drawn forwards by
two pair of muscles (h) which descend from
the under and lateral parts of the head to be
inserted into its back part. But neither of
these muscles pass through a sheath, as do the
corresponding muscles in the Nautilus.
A pair of muscles, whose important charac- '
ter is only perceived by tracing them through
their successive stages of development to the
Nautilus, are those small fasciculi which Cuvier
terms “a bride laterale qui joint la bourse a
la masse viscerale.”. (7.) They arise in con-
4

—— a,

junction with the fibres of the fleshy tunic of
the liver, but soon quitting these, extend, as
distinct fasciculi, downwards and outwards,
being perforated in their course by the great ,
lateral nerve, and are inserted into the upper j
part of the capsule of the rudimental shell, F
which the styles above-mentioned represent. u
In the Sepia they are proportionally larger, ,
corresponding to the greater development of .
the shell. They are not inserted, in the Octo- 5
pus, into the cartilaginous substance of the in-
closed style; nor, in the Sepia, into the calca-
reous substance of the cuttle-bone; neither
are they attached to the calcareous matter of
the shell in the Nautilus, where they acquire
their maximum of development. They termi-
nate in this, as in the preceding genera, in the
epidermic capsule of the shell, which has a
much closer and more intimate adhesion to
the testaceous substance in the Nautilus than
to the internal rudiment of the same part in the
naked Cephalopods. —
It is well known that zoologists are divided
in opinion as to whether the shell called Argo-—
nauta is formed by the cephalopod which in-
habits it or not. Having traced out the mus-
cles in the naked Cephalopods which are ana~
logous to those of the shell in the Nautilus, we
next examined the Ocythoé, with the view of

as

44

Wy

= eel
i
Re Ca

CEPHALOPODA. 531

ascertaining if these muscles presented a corre-
sponding degree of development, but found
them proportionally smaller even than in the
naked Octopus. All trace of internal shell has
disappeared in the Ocythoé; yet there is no
muscular connexion between the body and the
external shell which contains it.

The fleshy fibres of the mantle being white
like the rest of the muscles, and very compact,
are extremely difficult to follow in dissection.
Cuvier* observes, that in the Octopus those
which are external are evidently longitudinal ;
those which are internal, transverse; and that
there are short fibres which pass through their
thickness from one surface to another.

In the Cuttle-fish the muscular fibres of the
se part of the mantle recede laterally to
eave a large space for the lodgement of the
sepium or cuttle-bone, which is covered exter-
nally by a thin and flaccid skin: the rest of the
mantle is formed by a thick muscular tissue, as
in the Poulp. The lateral fins are connected
not only by the skin, cellular tissue, and vessels,
as Cuvier describes, but by a distinct though
thin stratum of muscular fibres; these arise
from the lateral and dorsal aspects of the apo-
neurotic capsule of the rudimental shell, and
are inserted into the spinal ridge of the alar
cartilage (h, h, fig. 212); from this ridge pro-
ceed the fibro-cartilaginous lamine and inter-
mediate muscles, which are disposed perpen-
dicularly to the ridge, and extend to the mar-
gins of the fin.

In the Calamaries the muscles which con-
nect the terminal fins to the body are still
more distinct. By means of these fins they
are enabled to propel themselves forward in
the sea; and there is good reason for believing
that some of the small slender-bodied subu-
late species of this genus are enabled to strike
the water with such force as to raise them-
selves above the surface, and dart, like the
flying fish, for a short distance through the
air.t

Dicestive System.—The animals which we
have thus seen to be endowed with so various
and formidable means for seizing and over-
coming the struggles of a living prey are pro-
vided with adequate weapons for completing
its destruction, and preparing it for deglutition.
These consist of a pair of strong, sharp, hooked
mandibles, which are of a horny texture in the
Dibranchiate Cephalopod, (a, 6, fig. 218,)
where they are fitted for cutting and tearing the
softer animals which they are enabled to catch;
but are strengthened by a dense calcareous sub-
stance in the Nautilus, (a, b, fig. 217,) which,
from its more limited sphere of action, is pro-

* Mémoire sur le Poulpe, p. 11.

t See Proceedings of the Zool. Society, Pt. i,
1833, p.90. The faculty possessed by the Cala.
maries of darting through the atmosphere was not
unknown to the ancients, Pliny ( Hist. Nat. lib.
ix. tom. ii. p. 105, Cuvier’s Ed.) says, ‘* Loligo
etiam volitat, extra aquam se efferens, quod et
pectunculi faciunt sagitte modo ;” and so general
appears to have been this belief that Varro sup-
posed the name Loligo to be a corruption of Voligo.
*<Loligo dicta, quod subvolat, littera commutata,
primo Voligo.”— De Ling. Lat. lib. iv. p. 21.

bably restricted in regard to food to such crus-
taceous and testaceous animals as it may sur-
prise by stealth, and whose defensive armour it
is thus enabled to break up.*

The mandibles, which are hollow sheaths,
like the horny covering of the beak of a Bird
or Tortoise, are fixed upon a firm fleshy sub-
stance, (c, c, fig. 217,) which resembles the

Mandibles of the Nautilus.

animal part of bone after the earth has been
removed by means of an acid. At the base of
the mandibles the fibrous structure of this part
becomes apparent, and a strong stratum,
(g, fig. 217,) passing between the bases of the
mandibles, serves for their divarication; their
closure is effected by fasciculi of muscular
fibres, which surround them externally near
the reflection of the circular lip. When the
mouth is closed, the lower mandible (6) over-
laps the upper (a).

The oral aperture is in the centre of the
base of the feet, and appears in the form of a
small circular orifice, formed by the contracted
fleshy lip which surrounds and more or less
conceals the mandibles.

In the Nautilus the margin of the lip (c) is
beset with several rows of elongated papille,
irregularly disposed ; external to which are
the labial processes with their tentacles :
these, in the specimen we dissected, com-
pletely overlapped and concealed the oral ap-
paratus.

In the Calamaries the jaws are surrounded,
external to the fringed circular lip, by a thin
membrane, which is produced into short pyra-
midal processes, corresponding in number to
the eight feet, and supporting minute rudimen-
tal suckers ; thus imitating the external feet,
as the labial processes of the Nautilus repeat
the structure of the digital processes. In the
genus Sepioteuthis the circular lip immediate!y
surrounding the jaws is tumid and _ plicated,
but not papillose ; external to it are two cir-
cular ridges of membrane, then a thin mem-
brane with jagged margins, and lastly a mem-
brane with its margin produced into eight
angular processes, which are not, however,
free, as in Loligo, but are tied down in the
interspaces of the eight legs; small rudimental
suckers may be observed on these processes.

* The digestive canal of the Nautilus was found
filled exclusively with the remains of a species of
crab.

532

In Onychoteuthis the inner lip (@, fig. 218) is
tumid, and merely subplicated ; the angles of
the external labial membrane are extended
along the middle of each foot for a short dis-
tance. In Sepia the inner lip is fringed, as in
Nautilus. The outer lip is tied down by mus-
cular bands to the bases of the arms, but sends
forward eight short, conical, unarmed processes.
In Loligopsis and Cranchia the outer-lip sends
off a muscular band to the base of each arm,
but has no free processes. In Octopus the
suckers commence immediately round the mar-
gin of the oral aperture, which is so con-
tracted that the mandibles can seldom be seen
without dissection: the
inner-lip is fimbriated, as in
Sepia. In Ocythoé it 1s
tumid and entire, but pli-
cated both circularly and
transversely.

The tongue is alarge and
complicated organ, and is
constructed on the same
plan in both orders of
Cephalopods. In the Nau-
tilus it is supported by an
oblong horny transversely
striated substance, which
appears to represent the
body of an os hyoides (a,
Jig. 236.) The posterior ex-
tremity of this substance is
free, or connected only by a few filaments with
the parts above, but its anterior extremity is
embraced bya pair of retractor muscles (6),
which originate from the posterior margins of
the lower mandible. The fleshy substance of
the tongue, thus supported, is produced ante-
riorly, and forms three caruncles (c), very soft
in texture, and beset with numerous papille,
having all the characters of a perfect organ of
taste. The anterior or terminal caruncle is the
largest, and four delicate retractor or depressor
muscles (d) are inserted into it. Behind the
caruncles the dorsum of the tongue is encased
with a thin layer of horny matter, about five
lines in length, from which arise four longitu-
dinal rows of slender prickles (e), which are
from one to two lines in length, and are in-
curvated backwards. ‘The number of these
prickles is twelve in each row, singularly cor-
responding with the number of tentacles given
off from the labial processes.

It is unnecessary to allude to the obvious
utility of this structure in seizing the morsels
of food, and directing them towards the gullet,
after they have been broken up by the mandi-
bles. Behind this horny part the tongue again
becomes soft and papillose (f), but the papille
are coarser and larger than those on the anterior
portions. Two broad fleshy processes (g, g,)
project forwards from the sides of the fauces:
these also are papillose, and are perforated in
the middle of their inner surfaces by a small
aperture (A, h), which leads into a glandular
cavity, situated between the folds of the mem-
brane, and analogous to the superior pair of
salivary glands in the Poulp, Calamaries, &c.

In the Dibranchiate Cephalopods the tongue.

CEPHALOPODA.

Fig. 218.

Section of the Beak, with the Tongue of an Onychoteuthis.

is similarly composed of an anterior and pos-
terior papillose and a middle spiny portion.
In the specimen from which the figure oe
was taken, the anterior fleshy portion (e
was slightly divided into three parts, but was
retracted by a single round muscle, and the
papille were relatively fewer and coarser than
in the Nautilus: at its sides there were several
orifices of glandular follicles. The horny plate,
covering the middle part of the tongue, is bent
at right angles; the recurved hooks in the
Onychoteuthis are confined to the anterior and
vertical surface; they commence above or be-
hind in seven rows; but, as they descend, first
the two outer on each side blend together, and
then each united row joins the next, so that
there remain but three rows at the lower part
of the sheath. In the Cuttle-fish the seven
rows of lingual spines continue distinct.

In the Onychoteuthis the posterior portion
of the tongue (g) is inclosed, as in the Nau-
tilus, between two faucial or pharyngeal folds
of membrane (A, 4), but their inner surfaces,
instead of being merely papillose, are beset
with rows of small recurved spines, which
must greatly assist the act of deglutition.

The superior salivary glands (2) are not con-
fined to the outside of the buccal mass, as in
the Octopus, but extend between the layers of
membrane which form the pharyngeal fold,
forming here a flattened mass (2); their duct
Opens at the bottom of a longitudinal fissure on
the inner surface of the fold; styles are repre-
sented passing into the ducts of these glands
in the figure.

In most of the Dibranchiata a second and

generally larger pair of salivary glands are

eee esl

CEPHALOPODA. $33

found below the cartilaginous cranium, situ-
ated in the hepatic cavity, on either side of
the esophagus. <A single excretory duct is
continued from each gland, and the two unite
and form one, as they are passing through the
cranium. The common duct penetrates the
lower or central surface of the buccal mass,
and is continued along the concavity of the
lower mandible, through the tongue to the
lower part of the spiny plate, where it termin-
ates. In the Octopus these glands are very
large, and have a smooth surface (q, fig. 233) ;
but in many Cephalopods, as in Ocythoe,
Sepiola, and Rossia, they are relatively smaller,
and haveagranular surface. It is in the genus
Loligopsis alone that these glands have hither-
to been found wanting.

With respect to the ultimate structure of the
salivary glands of the Cephalopoda, Miiller*
observes that they are not composed of solid
acini or granules, but of hollow canals or cells.

Before the description of the abdominal
viscera is proceeded with, it is necessary to
make a few observations on their position and
connections.

In the ventricose and short-bodied species
of Cephalopoda the mantle-sac is almost wholly
filled with the viscera, but in those of an elon-
gated form they are more or less confined to
the lower part of the sac, and a vacant space
intervenes between the visceral mass and the
opening of the mantle, which is traversed by
the respiratory currents: the part of the mantle
unoccupied by the viscera is most remarkable
for its extent in the genus Loligopsis (fig. 223.)

If the mantle of the common Octopus or
Poulp be laid open longitudinally, and a little

to one side of the mesial line, a cavity will bes

exposed, separated by the longitudinal muscular
septum (c, fig. 216) from the corresponding one
of the opposite side; in these two cavities are
contained the branchie (7, fig. 216), the termi-
nations of the oviducts (p ), and the pericardial
apertures (¢ ). Below and behind the branchial
cavities, the peritoneum is seen enveloping the
rest of the viscera; but this great serous sac is
subdivided into many compartments. If the

int of the scissors be inserted into the project-
ing orifice internal to the root of the gill (i, fig.
226), and the cavity of which it is the outlet be
laid open, the branchial ventricle, the branchial
division of the vena cava, and its appended
follicles will be exposed; this cavity is sepa-
rated from a corresponding one on the opposite
side by the systemic heart and the great vessels,
which are contained in a distinct serous com-
partment. In the Nautilus the two lateral and
the middle cavities form one large pericardiac
chamber, appropriated to the heart and great
vessels, and the venous appendages.

Behind these cavities, the peritoneum is
disposed so as to form several compartments :
one, which commences at the cranial cartilage,
extends downwards as far as the middle of the
branchiz, and contains the esophagus, the
inferior salivary glands, the crop, and anterior
aorta: in front of this, but commencing a little

* De structura glandularum penitiori, fol. p. 54,

lower down, is a second, which includes the
liver and ink-bag. These two cavities are sur-
rounded by a common muscular tunic, of
which we have already spoken, and the lower
part, which resembles a diaphragm, is per-
forated by the gullet, the aorta, and the two
biliary ducts, each of which has a distinct
aperture. The receptacle which contains the
gizzard is situated immediately beneath the
cesophageal sac; that in which the spiral py-
loric appendage is lodged lies immediately
behind the left compartment of the pericar-
dium. The intestine is principally contained
in a serous cavity behind the right division of
the pericardium ; and the bottom of the sac is
occupied by the cavity containing the organs
of generation.

The digestive organs in the Tetrabranchiate
Cephalopods would appear to differ in a less
degree than other parts of their organization from
the structures observable in the higher order:
in the Nautilus they present the following con-
formation.

The pharynx (f, fig. 217) or commence-

Fig. 219.

Digestive Organs, Nautilus Pompilius.

ment of the gullet, has numerous longitudinal
ruge internally, and is evidently capable of con-
siderable dilatation. The csophagus, after
having passed beneath the brain, or commissure
of the optic ganglions, dilate into a capacious
pouch or crop (k, fig. 219) of a pyriform shape,
two inches and three lines in length, and an
inch in diameter at the broadest part. From
the bottom of this crop is continued a contracted
canal (/, fig. 219,) of about three lines in diame-
ter, and half an inch in length, which enters the

534
upper of. an oval gizzard (m, fig. 219)
situated at the bottom of the pallial sac.

Close to where this tube enters, the intestine
(n, fig.219) is continued from the gizzard,
and after a course of a few lines communicates
with a small round laminated pouch or ap-
pendage ig , fig. 219) analogous to the spiral
cecum of the Cuttlefish, into which the biliary
secretion is poured: from thence the intestine
is continued, twice bent upon itself, but with-
out varying materially in its dimensions, to its
termination (0, fig. 219). In this course it
first ascends for about an inch and a half,
then makes a sudden bend down to the bottom
of the sac, and returns as suddenly upon itself,
passing close to the pericardium, and terminat-
ing between the roots of the branchiz.

The alimentary canal is every where con-
nected to the parietes of the abdomen by
numerous filaments; the only trace of a me-
sentery exists between the two last portions
of the intestine, which are connected together
by membranes including the ramifications of
an artery and vein.*

The longitudinal ruge, into which the
lining membrane of the esophagus is
thrown, disappear at its entrance into the
crop. The muscular coat of the crop con-
sists of an exterior layer of close-set circu-
lar fibres and an inner layer of more
scattered longitudinal ones. The lining
membrane is thin but tough, with a
smooth surface : when the cavity is empty,
it is probably thrown into longitudinal
folds by the action of the circular fibres.

In the canal which leads to the gizzard,
the lining membrane puts on a villous
appearance and is disposed in distinct
close-set longitudinal ruge.

The gizzard is girt by two broad radiate

a, %

Alimentary Canal of the Poulp.t

* In the specimen of the Nautilus from which
the preceding account is derived, the whole alimen-
tary canal was filled with fragments of some species
of crab, among which portions of branchiz, claws,
and palpi, were distinctly recognizable. The crop
in particular was tensely filled with these substances,
and the capability o propelling such rude and
angular particles through a narrow canal in the
gizzard, without injury to the thin tunics of the

CEPHALOPODA.

LAX
<8

muscles, of the thickness of two lines, arising
from opposite tendons: it is lined by a thick
cuticular membrane, delicately furrowed and
adapted to numerous fine ridges which tra-
verse longitudinally the whole interior of the
cavity. This, as is commonly found in gizzards,
was detached from part of the parietes and
adhered very slightly to the remainder. Nel

The pyloric orifice is close to the cardiac,
and is guarded by a valve, to prevent a too
ready egress of matter from the gizzard.*

The globular cavity (p, fig. 219) which
communicates with the intestine at a little dis- :
tance from the pylorus, is occupied with broad
parallel lamin, which are puckered trans-
versely, so as to increase their surface for vas-
cular ramifications; their texture under the
lens is follicular and evidently fitted to secrete.

The bile enters this cavity at the extremity
furthest from the intestine by a duct large
enough to admit acommon probe. The two
lamine on each side the entrance of the duct
increase in breadth as they approach the in-
testine, and are continued in a curved form

i ee ee ee Se ee

Fig. 220.

f

preparatory cavity, is a remarkable example of the __
superior powers of living over dead matter. _—
The contents of this part of the alimentary _
canal were in smaller pieces than in the cro
but of the same nature; the fragments of shell we
comminuted apparently by mutual attrition, as th
were no particles of sand or pebbles present. _
+ From Férussac’s Monograph on the Cépha
Acetabuliféres.

CEPHALOPODA.

along that canal, being gradually lost in its
inner membrane, the lamina next the gizzard
is peculiarly enlarged, so as evidently to pre-
sent an obstacle to the regurgitation of bile
towards the gizzard. The inner surface of the
rest of the intestinal canal presents a few lon-
gitudinal ruge, with slightly marked transverse
puckerings.

In the Dibranchiate Cephalopods the gul-
let, in consequence of the position of the
stomach near the lower part of the visceral
sac, is of great length (a, a, fig. 221), but
varies in this respect according to the form
of the animal. e have seen that in the
Nautilus it is dilated into a pyriform crop;
a similar dilatation occurs in the genus Octo-
pus; but its position is reversed, the larger end
of the sac being uppermost, and probably as
the result of the habitually reversed position of
the animal with the head downwards, the crop
is extended into a large cul-de-sac above the
part where the esophagus opens into it (6,
Sig. 220). From this part the crop gradually
contracts to its termination.

In the Argonaut the crop commences by a

similar lateral dilatation, but is continued of

almost uniform breadth to the stomach.

In the Sepia, Sepiola, Rossia, Onychoteuthis,
Loligopsis; and Loligo, and probably in the
other Decapods, there is no crop, the gullet
being continued of uniform breadth to the
stomach (a, a, fig. 221).*

The stomach (c, figs. 220, 221,) in all the
Dibranchiate Cephalopods is a more or less
elongated sac, having its two orifices, the car-
dia (d) and pylorus (e), close together at the
anterior or upper part of the sac, as in the
ate of birds: the muscular fibres are simi-
arly disposed, and radiate from two opposite
tendons; they form a stratum of about the
same thickness as in the stomachs of omnivo-
rous birds. The epithelium, which is con-
tinued from the esophagus and crop (a’, U’,
fig. 220) acquires a greater thickness in the
gizzard, and is disposed in longitudinal ruge ;
it is readily detached from the muscular tunic.

The intestine, at a short distance from the
Nee communicates with a glandular and

minated sac, analogous to the pyloric ap-
pendages in Fish, but which in the Cephalo-
pods is always single.

In the Nautilus, we have shewn that this
rudimental pancreas (p, fig. 219) is of a sim-
ple globular form, as in the Doris and some
other Gasteropoda. It presents a similar form
in Rossia and Loligopsis, in the latter of which
it is of large size (g, fig. 223). In Argo-
nauta it is triangular; in some species of

* From this difference I conclude that Aristotle

took his description of the digestive viscera of the
Malakia from the Sepia or Teuthis: he says, Mera
BE rd ori Exouew oicopayoy paxpiy ual oreviv,
Sxcpeevoy 38 rovTou mpcAcRov paéyay ual dépipep
épwOi%n. ** After the mouth they havea long and
narrow esophagus, then a large round gizzard
similar to that of a bird.”— Hist. de Anim. lib. iv.
ce, 1.9. But it is evident that he also had dissected
the Octopus, as he afterwards notices the difference
in the position of the ink-bag, which occurs in this
genus as compared with the Sepia.

535

Loligo, as in the Loligo communis, it is ex-
tended into a long pyriform membranous bag,
but in the Loligo sagittata, Sepia, and Octopus,
it is elongated and twisted spirally, whence
it is compared by Aristotle to the shell of a
Whelk (f, figs. 220, 221). In each of these

Alimentary canal of the Sagittated Calamary.*

genera its cavity is occupied by glandular
lamine (g,g); the biliary ducts terminate be-
tween two of the largest folds, which make a
curve as they pass into the intestine, and are
continued, gradually diminishing in size, along
the canal, presenting at its commencement two
tumid projections, which tend to prevent a
regurgitation of bile towards the pylorus.

The intestine in the Nautilus makes a
loop, or narrow fold upon itself before
it is continued forwards to the base of the
funnel. In the Octopus it is characterized by
a similar fold, but in the Cuttle-fish and Cala-
mary the gut is continued in a straight line from
the stomach to the vent (i, ¢, fig. 221), and is
consequently very short and simple: in both
cases it maintains nearly a uniform diameter
to its termination.

The internal tunic of the intestine is dis-
posed in longitudinal folds, of which the two
at its commencement, above described (i, #,
fig. 220), are the most conspicuous. The lon-
gitudinal ruge in the Sepiotewthis and Cala-

* Home, Lectures on Comp. Anat, pl, Ixxxiii,

536

mary terminate abruptly where the duct of
the ink-bag enters the gut (k, fig. 221), which
for the small extent beyond this part is smooth
internally.

In the Octopods the intestine passes through
the muscular septum of the branchial cham-
ber, immediately above which it terminates.
In the Decapods the rectum and duct of the
ink-gland are surrounded by the muscular fibres
which connect the pillars of the funnel to one
another; in both cases the fibres serve as a
sphincter to the anus.

In many Dibran-
chiata, especially the
Decapods, the termi-
nation of the rectum
is provided with two
lateral fleshy appen-
dages; for which, as
far as we know, no use
has hitherto been as-
signed. In the Sepio-
teuthis these process-
es (a, a, fig.222) are
of a broad inequilate-
ral triangular form,
attached to the sides
of the transverse anal aperture (b) by their
acute angle, from which a ridge extended lon-
gitudinally to the middle of the base; when
the processes were folded down upon the vent
{as in A, fig.222), the ridge fitted into the aper-
ture, so as accurately to close it. In the
Cuttle-fish the corresponding processes are of a
rhomboidal form, with a thicker ridge onthe side
next the anal aperture, which they in like man-
ner are adapted to defend against the entrance
of foreign substances by the funnel. In other
genera they are not adapted to defend the anus
mechanically, being elongated and filiform;
but they probably serve to give warning
of the presence of foreign bodies, and excite
the necessary contraction of the constrictors
of the gut; Rathké compares them to antenne
in the Loligopsis, where the anal processes are
very long (11, fig. 223).

The apparatus for secreting the inky fluid,
formerly regarded as characteristic of the class
of Cephalopods, is wanting in the Nautilus,
which, as it has a large and strong shell to pro-
tect its body, stands less in need of such a
means of defence: the ink-bag is, however,
present in the Argonauta.

The ink-bag (J, fig. 221) varies in its re-
lative position in different Dibranchiata: in
the Cuttle-fish it is situated near the bottom
of the pallial sac, in front of the testicle or
ovary. In the Calamary it is raised close to
the termination of the intestine; we have found
it similarly situated in the Argonauta, Sepioteu-
this, and Rossia. In the Octopus it is buried
in the substance of the liver, a small part only
of its parietes appearing on the anterior sur-
face of that gland, from which its duct is con-
tinued forwards to terminate in this genus im-
mediately behind the anus.

. From this connection of the ink-bag with
the liver in the Poulp, Monro was led to sus-
pect it to be the gall-bladder. What its real

Anal valves, Sepioteuthis.

CEPHALOPODA.

nature may be still remains doubtful ; De Blain-
ville and Jacobson regard it as a rudimental
urinary apparatus :* Sir Everard Home + com-
pares it to the secreting sac which opens into
the rectum in Rays and Sharks, and this we
consider to be the true homology of the ink-
bag. It is interesting, indeed, to observe that
corresponding anal glandular cavities in the
Mammalia are in many instances modified to
serve by the odour of their secretion as a means
of defence, just as the part in question operates
in the Cephalopods by reason of the colour of
the ejected fluid.

When the ink-bag is laid open and well
cleansed of its contents, its inner surface is
seen to be composed of a fine cellular or
spongy glandular substance: its exterior coat
is of a tough white fibrous texture, and its
outer surface commonly exhibits a peculiar
glistening or silvery character.

The ink-bag probably attains its largest pro-
portional size in the genus Sepiola, where it
presents a trilobate form. It is of an oblong
pyriform shape in Sepia, Sepioteuthis, and
Loligo. It is relatively larger in Sepia than
in Octopus, and the quantity of water which
its contents will discolour is very surprising:
it behoves the anatomist, therefore, to be very
careful not to puncture this part during the
dissection of a Cephalopod.

In the living Cephalopods the inky fluid is
secreted with amazing rapidity ; we have seen
an Octopus, which had previously discoloured
the water for a considerable extent around it,
immediately after its capture continuing its
black ejections several times in quick succes-
sion, and ultimately expelling in convulsive jets
a colourless fluid, when the powers of secreting
the black pigment were exhausted.

In every species of Cephalopod which pos-
sesses this organ, the tint of the secretion cor-
responds, more or less, with the coloured spots
on the integument. The Italian pigment,
called ‘ Sepia,’ and the Chinese one, com-
monly called ‘ Indian Ink,’ both of which are
the inspissated contents of the organ above
described, afford examples of different shades
of this singular secretion. .

If the Cephalopods are enabled thus tocon-
ceal themselves during the day, they have also a
the power, by means of another secretion, to
render themselves conspicuous by night by
means of a phosphorescent exhalation.

Lhe Liver.—This gland is remarkable in the
Cephalopods, as in the other classes of the Mol-
luscous A abehinedne for its great proportional
size. In the Nautilus the liver (g, 9, fig. 219)
extends, on each side of the crop, from
the cesophagus to the gizzard. There is a
pimp of form, as will be afterwards seen,
etween this gland and the Respiratory organs,

Aa’
* Davy states that the secreted fluid is ‘¢ a car- —
bonaceous substance mixed with gelatine ;” but, —
according to Bizio, this secretion yields on analy
a substance sui generis, which he calls ‘ Melani
See Edinb. Philos. Journal, vol. xiv. p. 376. —
t Lectures on Comp. Anat. vol. i. p. 398.

ul
t See Oligerus Jacobeus de Sepizluce, in the —
Acta Hafniens, vol. v. p. 283. . ae

CEPHALOPODA.

for it is divided into four lobes, and these are
connected by a fifth portion, which passes
transversely below the fundus of the crop.
All these larger divisions are subdivided into
numerous lobules of an angular form, which
vary in size from three to five lines. These
lobules are immediately invested by a very
delicate capsule, and are more loosely sur-
rounded by a peritoneal covering common to
this gland and the crop.

The liver is supplied by large branches
which are given off from the aorta, (7, fig. 219,)
as that artery winds round the bottom of the
sac to gain the dorsal aspect of the crop. It is
from the arterial blood alone, in this, as in
other Mollusks, that the secretion of the bile
takes place, there being but one system of
veins in the liver, corresponding to the hepatic,
which returns the blood from that viscus, and
‘conveys it to the vena cava at its termination.
The colour of the liver isa dull red with a
violet shade ; its texture is pulpy and yielding.
When the capsule is removed by the forceps,
the surface Xa pi under the lens to be mi-
nutely granular or acinous, and these acini
are readily separable by the needle into clusters
hanging from branches of the bloodvessels and
duct. The branches of the duct arising from
the terminal groupes of the acini, form, by
repeated anastomoses, two main trunks, which
unite into one at a distance of about two lines
from the laminated or pancreatic cavity.

There appears to be one example in the
Dibranchiate Order where the liver is divided
into four lobes, as in the Nautilus; this occurs,
according to Dr. Grant, in the Loligopsis
guttata ; but in the figure which is given of
this structure the lobes are each distinct
from the rest, and divided at the middle
line; while in the Nautilus the four lobes are
united together. Rathké, on the contrary,
who has given an elaborate account of the
Anatomy of Loligopsis under the name of
Perothis,* describes and delineates the liver,
in the two species of that genus dissected by
him, as a simple undivided viscus, of an ellip-
soid figure, situated in the middle line of the
body (12, fig. 223). In Onychoteuthis Banksii
the liver is a single elongated laterally com-
pressed lobe, obtuse and undivided at both
extremities. In the Sagittated Calamary it is
single, elongated, and cylindrical. In Sepia
and Rossia it is divided into two lateral lobes,
both of which are notched at the upper extre-
mity. In the Argonaut the two lobes are
united for a considerable extent along the
mesial line, but are greatly produced laterally,
and advance forwards, narrowing towards a
point, so as partially to enclose the alimentary
canal. In Octopus the liver is a single oval
mass, flattened anteriorly. In Eledone it pre-
sents a spherical form, corresponding to the
ventricose form of the visceral sac. In the two
latter genera the ink-bag 1s enclosed within the

* TinpwOnc, mutilatus, a name applied to this
genus by Eschscholtz, in consequence or the gene-
rally mutilated condition of the tentacles. See
Mém. de l’Acad. Imp. de Petersbourg, tom. ii. pt.
1 & 2, p. 149, -

VOL. I.

537

capsule of the liver, but in the Argonaut and in.
all the Decapodous genera this is not the case.
The proper capsule of the liver is very delicate,
and apparently nothing more than the outer ter-
mination of the cellular tissue which connects
the lobules of its parenchyma. When this is

inflated from the biliary ducts, it is seen to be
Fig. 223.

composed of cells,
formed by the ulti-
mate ramifications of
the duct, with very
thin parietes, and re-
latively larger than
those of the liver of
the Snail. Thisisthe
structure observable
in the liver of the
Octopus, according
to Miuiller,* and
Rathké observed the
same structure in
the terminal ceeca of
the hepatic duct in
Loligopsis.

In the Octopo-
dous Dibranchiates,
which have a large
crop, and the lower
pair of — salivary
glands of corres-
pondingly large di-
mensions, the two
biliary ducts are
simple canals, which
are continued from
the lower end of the
liver, embracing the
origin of the intes-
tine, and uniting be-
low it to terminate
by a common orifice
in the pyloric ap-
pendage. Butinthe
Decapodous _ tribe
they continuetosend
' Viscera in situ, Loligopsis. Off branches, which

Lol. Eschscholtzit. subdivide and form
clusters of ccecal appendages, through a greater
or less proportion of their entire course. The
follicles thus appended to the biliary ducts
are larger than those which form the liver ; they
are figured by Monro in the Loligo sagittata
as the ovary, but were considered by Mr.
Hunter to represent the pancreas in the Cuttle-
fish, from which species he took the preparation
of these parts in his collection.t These folli-
cles are described with much care and detail
by Rathké in the genus Loligopsis, and, ac-
cording to him, in one species (10, fig. 223),
( Lol. Eschscholtzii,) they terminate, not in the
hepatic duct, but separately and directly in the
pyloric appendage. We have found these
cystic follicles appended to the hepatic duct in
Sepiola, Onychoteuthis, Sepioteuthis, and in
the genus Rossia, in which they present the
largest proportional development hitherto ob-

* De Glandularum Struct. Pen. p. 71.
+ See No. 775, Physiological Catalogue, Ato,
vol. i, p. 229. ;
2N

538
served in the class. Here the biliary ducts, as
soon as they emerge from the liver, branch out
into an arborescent mass of larger and more
elongated follicles than those constituting the
oo gg arenchyma; these ramifications extend
full half an inch from the hepatic duct, and
conceal the upper halves of both the stomach
and pyloric appendage.

Organs of Circulation.— Prior to the dis-
section of the Nautilus Pompilius the Ce-
phalopods were regarded as having three dis-
tinct hearts, a peculiarity which is not found in
the circulating system of any other class of
animals. In the Nautilus, however, there is
but one ventricle, which is systemic, as in the
inferior Mollusks; and the three hearts are,
therefore, characteristic only of the Dibran-
chiate or higher order of Cephalopods.

These differences in the circulating system of
thetwo orders areaccompanied with equally well
marked modifications of the respiratory organs;
and hence the primary divisions of the class
are each distinguished by characters of equal
value, and derived from modifications of those
organs which afford the most natural indica-
tions of the corresponding groups in the other
classes of the Molluscous division of Inverte-
brate animals.

In the Nautilus the veins which return the
blood from the labial and digital tentacles and
adjacent parts of the head and mouth, termi-
nate in the sinus excavated in the substance of

Circulating and Respiratory Organs, Nautilus Pompilius.

CEPHALOPODA.

the cephalic cartilage. From this sinus the great
anterior vena cava (a, fig. 224) is continued,
running in the interspace of the shell-muscles
on the ventral aspect of the abdominal cavity,
and terminating in a sinus (6) just within the
pericardium, where it receives the venous
trunks of the viscera. (These are indicated by
bristles in the figure.)

The structure of the vena cava is very remark-
able; itisofa flattened form, being included be-
tween a strong membrane on the lower or ventral
aspect, and a layer of transverse muscular fibres,
which decussate each other on the upperor dorsal
aspect; both the membrane and the muscle
pass across from the inferior margin of one
shell-muscle to the other; they consequently
increase in breadth as those muscles diverge,
and complete the parietes of the abdomen on
the ventral aspect. The vein, however, main-
tains a more uniform calibre by its proper
internal coat, leaving a space on either side
between the membrane and muscle. The ad-
hesion of the proper membrane to the muscular
fibres is very strong, and these, though ex-
trinsic to the vessel, form part of its parietes
on the dorsal aspect. There are several small
intervals left between the muscular fibres and
corresponding round apertures (a’) in the mem-
brane of the veinand contiguous peritoneum, by
which the latter membrane becomes continuous
with the lining membrane of the vein: from
this structure it would seem that the blood

CEPHALOPODA.

might flow into the peritoneal cavity, or the
fluid contents of that cavity be absorbed into
the vein.*

In the structure of the other veins of the
Nautilus nothing uncommon is_ observed:
their principal termination is in the sinus
above-mentioned, where the greater or systemic
circulation ceases, if we are to consider the
lesser circulation to commence where the blood
again begins to move from trunks to branches.

Four vessels, which, according to the above

view, are analogous to branchial arteries, (c, c, )
arise from the sides of the sinus, and proceed,
two on each side, to their respective gills. In
this course they have each appended to them
three clusters of short, pyriform, closely aggre-
gated, glandular follicles (d,d). The larger
cluster is situated on one side of the vessel,
and the two smaller on the opposite. Each of
these clusters is contained in a membranous
receptacle communicating with the pericar-
dium, and formed by partitions projecting from
its inner surface. In these partitions we ob-
served a fibrous texture, which conveyed an
impression that they were for the purpose of
compressing the follicles and of discharging
such fluids as might exude through their pa-
rietes into the pericardium, whence it might be
expelled by the papilliform apertures at the
base of the gills into the branchial cavity.t
The follicles, however, terminate by their pro-
per apertures in the interior of the dilated parts
of the vessels to which they are appended :
(these are shewn on the right side at d’,d’.) We
shall revert to these singular bodies in the de-
scription of the circulating organs of the Di-
branchiata.
_ The branchial arteries having reached the
roots of the gills become contracted in size,
and their area is here occupied by a valve which
Opposes the retrogression of the blood. Each
vessel, then, penetrates the fleshy stem of the
branchia (e), where it dilates into a wide
canal, which presents a double series of orifices
through which the blood is driven by the
contraction of the surrounding muscular sub-
stance, into the vessels which extend along the
concave margins of the branchial lamine.

The few, oo vein (f)) receives the aerated
blood from vessels extending along the convex
margins of the respiratory lamine, by a series
of alternate slits, and is continued down the
anterior or inner side of the gill. After quit-
ting the roots of the gills each vein crosses its
corresponding artery on the dorsal aspect, and
is continued, without forming a dilatation or
sinus, to the systemic ventricle, where regurgi-
tation is prevented by a single semilunar valve
at the termination of each vein.

The ventricle (g) is of a somewhat com-
pressed and transverse quadrate form: its mus-
cular parietes are nearly a line in thickness,
and present internally a decussated structure.

* For a further description of this structure, its
analogies, and probable uses, see ‘ Memoir on the
ag! Nautilus,’ p. 27 et seq.

+ We found the pericardium in the specimen
dissected filled with coagulated matter accurately
moulded to the different parts which contained it.

x

539

Two arteries arise from it ; one superior and
small (h), whose orifice is furnished with a
double valve; the other inferior and of large
size (2), coming off from near the left angle of
the ventricle, and furnished with a muscular
bulb about five lines long, at the termination
of which there is a single valve; and which
ought rather to be considered as a continuation
of the ventricle. The lesser aorta gives off a
branch to the great gland of the oviduct; a
second, which is continued down the membra-
nous siphuncle of the shell; and a third to the
fold of intestine (1). The larger aorta passes
downwards between the gizzard and ovary, and
renders vessels to both these viscera. It then
winds round the bottom of the pallial sac, sends
off large branches to the liver, and gains thedorsal
aspect of the crop, along which it is continued,
distributing branches on either side to the
great shell-muscles, to the cephalic cartilage,
where it divides into two equal branches,
which pass round the sides of the esophagus,
and furnish branches to the mouth, the sur-
rounding parts of the head and the funnel.

In the Dibranchiata the veins of each arm
form two principal branches, which descend
along the lateral and posterior parts of those
appendages; each lateral vein unites at the base
of the arm with the opposite vein of the adjoin-
ing arm; the united vessel is joined by another
similarly formed ; and the whole of the venous
blood is thus ultimately conveyed to an irre-
gular circular sinus, from the anterior part of
which, between the head and the funnel, the
great anterior cava is continued. In the Octo-
pus this vessel (a, fig. 226) is provided with
two semilunar valves, where it communicates
with the venous circle. A little below this
part it receives the veins of the funnel; then
those of the anterior part of the liver (6) and
of its muscular envelope. Upon its entrance
into the pericardium the vena cava divides
without forming a sinus as in the Nautilus ;

and sometimes before, sometimes after its divi-

sion it is joined by two large visceral veins
(c). Thus reinforced, each of the divisions
(d,d) proceeds downwards and outwards to
the lateral or branchial heart of its correspond-
ing side; but previous to opening into the
ventricle it dilates into a sinus (¢), which also
receives the venous blood from the sides of the
mantle and the fleshy and vascular stem of the
branchia, by the vein marked _/f.

Both the divisions of the vena cava and the two
visceral veins, after having entered the pericar-
diac or venous Cavity, are furnished with clusters
of spongy cellular bodies (g, g), which open
into the veins by conspicuous foramina, like the
venous follicles of the Nautilus above described.

In no species of Cephalopod which has hi-
therto been anatomized, have these appendages*
been found wanting; but they vary in form in
different genera. In the Genus Eledonet+ they

* From a consideration of the different particu-
lars given in Aristotle’s anatomical description of
the Cephalopods, Kohler supposes the part which
he calls putts, mytis, to have been the glandular
appendages of the veins above described. rs

+ Carus, Vergleich. Zootomie, tab. iv. fig. viil.
x, Eledone Moschata. BAP

N

540

& ‘

CEPHALOPODA.
Fig. 225.

SS EROS
*

See - _ - = ™

~S BAAS

<A wb Rt WV bivace

SS

}

Circulating and respiratory organs— Cuttle-fish.*

form thin colourless pyriform sacs, extending
nearly an inch from the vein. They are ar-
ranged in distinct clusters, and are relatively
shorter in Argonauta. In Sepioteuthis the
whole extent of the superior and inferior trunks
of the veins contained in the pericardium pre-
sent an uniform and continuous cellular en-
largement of their parietes. In Loligo the
coats of the corresponding veins in like man-
ner present only a spongy thickening. In
Sepia the cells are more elongated, but are
large, irregular, and flocculent (c,c, fig. 225),
and continued without interruption not only
upon the divisions of the vena cava (a), but
upon the visceral veins, two of which (6,b)
present remarkable dilatations.

In Loligopsis the venous follicles are in
distinct groups, as in Nautilus; and Rathké
describes them as presenting a laminated and
glandular structure.

With respect to the function of these bodies
nothing is as yet definitely known. They are
well supplied with blood from the neighbouring
arteries, and are undoubtedly glandular; but
the matter which they secrete has not yet been
subjected to chemical analysis. If the spongy
coats of the vena cava of a Calamary be
pressed, a whitish fluid escapes, which is al-

* From Home’s Comparative Anat. vol. iv. See
the original figure and description by Hunter, in
Descr. Catalogue of Mus. R. Coll. of Surgeons,
vol. ii. pl, xxil.

which circulates in the vein. The elongated
cells of the Poulp yield in like manner an
opake and yellow mucus. “Some physiologists
suppose that the secreted matter is not expelled
by the orifices of the sacs into the veins to be
mixed with the current of blood, but that the
venous blood passes into the cells by those
apertures, and that the matter secreted from it
exudes from the parietes of the cells or follicles
into the great serqus cavity surrounding them.
Mayer, considering that the urine is secreted
from venous blood in the lower vertebrate
animals, regards these venous appendages as
the renal organs of the Cephalopods; the serous
sacs (h, fig. 226), therefore, which Cuvier calls
the ‘ great venous cavities,’ and which we have
termed the ‘ pericardium,’ the German Physi-
Ologist calls the ‘ urinary bladder;’ and the
papillary orifices (i) leading into the branchial —
or excrementory chamber, which we have com=- —
pared with the orifices leading from the peri- —
cardium of the Ray and Sturgeon into the
peritoneal cavity of the abdomen,t Mayer calls —
the urethre. It must be observed, however,
that this Physiologist does not advance any
proof from chemical analysis in support of his
theory. Cuvier, on the other hand, believing that
the water of the branchial chamber might have
access by the orifices to the cavities contai
the appendages in question, supposes that

ways thicker and more turbid than the blood .
:
4
r

t Memoir on the Nautilus, p. 33.

CEPHALOPODA.
Fig. 226.

“ Viscera of Poulp.*

May serve as accessory respiratory organs. The
valvular structure of the orifices is opposed,
however, to this view; while it supports the
doctrine of their being excretory outlets.
_ The venous follicles may, therefore, serve as
emunctories, by means of which the blood is
freed of some principle that escapes from their
external pores; or they may alter the blood by

adding something thereto; or, like the spleen,
they may assist in converting arterial to venous
blood. As a secondary function they may
Serve as temporary reservoirs of the venous
blood whenever it accumulates in the vessels
either from a general expansion, or from a partial
impediment in its course through the respi-
ratory organs; and thus the cells or follicles,
which- are endowed with a motion of systole
and diastole, like the auricles of the heart, may
serve to regulate the quantity of blood trans-
mitted to the gills.

The branchial ventricles (d, d, fig. 225) are
appended to the roots of the gills: in the Octo-
poda they are simple pyriform muscular cavities

k, k, fig. 226,) generally of a blackish grey co-
our; in the Decapoda they are elliptical or trans-
versely oblong, of a light grey or pale red co-
lour, and have a white fleshy appendage (e, e,

Sig. 225,) hanging to their lower surface or
their external side. The connecting pedicle is
hollow, and communicates with a small cavity
in the substance of the appendix. Internally
these ventricles are deeply impressed with cells

* From Mayer, Analecten fiir Vergleichende
Anatomie, tab. v.

541

and decussating carnese
columne (k, fig. 226),
and where they com-
municate with the ve-
nous sinus two semi-
lunar valves (1) are
placed to prevent re-
gurgitation. Their func-
tion is to accelerate
the circulation through
the branchie ; and by
this simple addition to
the respiratory appa-
ratus, the two gills of
the Dibranchiata are
rendered equal to the
office of preparing the
blood to maintain the
increased muscular ex-
ertions, and_ repair
all the corresponding
waste which the vital
economy of this highly
organized group of
Molluscous animals
occasions.

The branchial veins
(m, m, figs. 225, 226)
return, as in the Nauti-
lus,along the internal or
unattached side of the
commissure of thebran-
chial lamine ; and, as
they approach the sys-
temic ventricle, generally dilate into a sinus (7)

Fig. 227.

Systemic Ventricle, Onychoteuthis.

542

on each side ; these sinuses are relatively larger
in the Sepia than the Octopus. In both species
the branchial vein resumes its ordinary dimen-
sions before terminating in the ventricle; but in
the Cuttlefish the sinus is placed closer to the
ventricle.

The systemic ventricle (0) is situated in the
mesial plane between the bifurcation of the
vena cava above, and the ovary or testis below.
In the Octopus and Eledone it presents a glo-
bular form, rather extended tranversely, and
with the branchial sinus entering at its superior
and lateral aspects. In the Loligo and the
Onychoteuthis (fig. 227) it is lozenge-shaped,
with the long axis in the axis of the body;
giving off the two aorte (c, d) by the anterior
and posterior angles, and receiving the bran-
chial veins (a, a, ) at the lateral angles. In the
Sepia, (0, fig. 225,) Sepioteuthis, and Rossia,
the systemic ventricle is a fusiform body, bent
upon itself at right angles. About one-half on
the right side lies in the axis of the body, the
remainder extends transversely to the left side ;
the extremity of this part receives the left bran-
chial vein, the other extremity gives off the an-
terior aorta (q, fig, 225). The bulb of the
posterior and generally the larger aorta (p, fig.
225) is continued from the middle of the
transverse portion; the right -branchial vein
enters the middle of the right side of the lon-
gitudinal portion of the ventricle.

In all the Dibranchiata the parietes of the
systemic heart, though thin, are firmer and more
muscular than those of the branchial hearts; and
its cavity is generally about three times greater
than that of either of the others: its inner
surface shows the regular interlacement and
decussation of the columne carne, none
of which, however, project into the cavity.
The termination of each branchial vein is
defended by a pair of membranous semi-
lunar valves (b, fig. 227). The origin of the
lesser aorta (p), arising from the anterior part
of the ventricle, is defended by a single valve
(e, fig. 227); that of the great aorta, (9’, fig.
226,) which, though posterior in its origin, is de-
stined to supply the head and anterior parts of
the body, is generally provided with a mus-
cular bulb, as in the Nautilus. In the Octopus
it is defended, according to Cuvier, by two
semilunar valves; but in the Calamary and
Onychoteuthis by a single valve (f, fig. 227).
In the Octopus there is also a third small
artery (7, fig. 225) given off directly from the
ventricle, which is distributed to the generative
organs, and presents considerable periodical
variations of size in relation to the functions
of those parts. In the same genus the small
aorta, which arises from the anterior part of
the ventricle, first gives off two long and slender
branches (s, s, fig. 226), which are distributed
to the venous follicles, whose arterial vascularity
we have before mentioned. The trunk then di-
vides into two arteries, of which the largest (¢)
ascends in front of the vena cava to be distri-
buted to the mantle; the other supplies the
folded intestine and surrounding peritoneum.
The large aorta first passes backwards and to
the right between the layers of peritoneum

CEPHALOPODA.

which separate the intestinal sac from that of
the pyloric appendage and that of the stomach;
winds round the latter, and passes, by a proper
opening, to the right of the cardia through the
muscular septum, and into the cavity behind
the liver, and ascends on the right side of the
dilated cesophagus to the cartilaginous cranium.
Here, after distributing branches to the sur-
rounding parts, it bifurcates and completely
encircles the gullet; and from this vascular
ring, which is strikingly analogous to the bran-
chial arches in Vertebrata, the head and all its
complex radiating appendages derive their nu-
triment.

ResprraTory Orcans.—The branchie pre-
sent the same general form and structure in both
orders of Cephalopods, but differ, as before ob-
served, in number, and also in their mode of
attachment to the mantle. They are always
entirely concealed and protected by the mantle,
which is extended forwards so as to form a
peculiar chamber for them anterior to the other
viscera, and into which the rectum and gene-
rative organs open. It is interesting to perceive
the respiratory cavity retaining, in the highest
organized Mollusks, that relation with the anal
extremity of the digestive canal which we trace
through the whole of this type of animal con-
formation, and which forms so well-marked a
line of distinction between the Molluscous and
Vertebrate divisions of the animal kingdom.

In the Nautilus the four branchiz are at-
tached by their bases only to the inner surface of
the mantle; but in the Dibranchiates a thin
fibrous membrane connects the fleshy stem of
each gill to the contiguous surface of the man-
tle. In the Nautilus the branchize are subject
to contortions from the want of this support;
and in the specimen which we dissected, we
found the gills on one side closely bent upon
themselves, with their apices turned down; this
circumstance does not probably impede a cir-
culation which flows, with an equable and con-
tinuous current through the gill; but where the
blood is driven in jerks by the contractions of
a powerful ventricle, a necessity then exists for

the provision of a free channel for the passage of _

the fluid; and accordingly we find that the
obstruction of the branchial artery by the
bending of the fleshy stem of the gill is obvia-
ted by the simple but effectual means above
described, viz. the superaddition of a connect-
ing membrane, which always preserves the gill
in a straight position.

In both orders of Cephalopoda the branchize
present an elongated pyramidal figure, with their
apices directed forwards: they are compressed
from before backwards in the Nautilus (2, m,
Sig. 224), and from side to side in the Cuttle-fish
(i, k, fig-225) and most other Dibranchiates.
They are composed of a number of triangular
vascular lamin extendingtransversely from each
side of a central fleshy stem (h, fig. 225), having
an alternate disposition : each lamina is com-
posed of smaller transverse lamine, which are
again similarly subdivided ; the entire gill thus
exhibiting the structure called by botanists ‘ tri-
pinnate,’ by which an extensive surface is afford-
ed for the minute division of the branchial vessels.

S

|
:

CEPHALOPODA.

In the Nautilus (fig. 224) there is a larger and
smaller branchia on each side; the larger and
external branchia (m_) presents forty-eight pairs
of lamine; the smaller branchia (7 ) thirty-six.

In the Dibranchiates the gills vary in the
relative size and number of laminz in different
genera; they are, perhaps, proportionally small-
est in the Loligopsis, where, according to
Rathké, the number of branchial laminz does
not exceed twenty-four pairs; and it is inte-
resting to observe in this genus that the mus-
cular structure of the mantle has a correspond-
ingly feeble development. In the Cuttle-fish
the branchie are each composed of thirty-six
pairs of triangular lamine: in the Sagittated
Cal: of sixty pairs of lamine.

As the branchiz of the Cephalopods are un-
provided with vibratile cilia, respiration is
effected by the alternate dilatation and contrac-
tion of the branchial chamber ; in the first ac-
tion the sea-water rushes in by the anterior aper-
ture of the mantle ; by the second it is expelled
through the cavity of the funnel. As in other
classes, respiration is performed more quickly
in the young than in the full-grown animals :
Dr. Coldstream witnessed an Eledone, which
measured one inch and a half in length, respire
eighteen times in a minute; while one of the
same species, which measured four inches in
length, respired ten times in a minute. The
proper direction of the respiratory currents is
insured by various mechanical contrivances ; in
the Nautilus, the funnel passes through a hole in
the substance of the mantle, which fits it so
closely, that at the moment when the funnel is
distended by the expiratory stream, no space is
left external to it by which the water can
escape ; and the greater the force by which the
water is driven into the funnel, the closer is it
girt bythe mantle. In the Poulp and Eledone,
where the funnel is connected to the fore part
of the neck, and the mantle passes across its
base, two large valvular folds (one of which is
shown at v, fig. 216) are extended from its sides ;
these are concave towards the respiratory sac;
they subside during inspiration, and the parietes
of the funnel at the same time are collapsed ;
the latter during expiration are dilated, while
the valves are raised and expanded, and thereby
prevent the ejected currents from passing out-
side the funnel. In the Argonaut, and in
all the Decapods, except the Loligopsis and
Cranchia, the sides of the funnel are articula-
ted to the opposite sides of the mantle by ball-
and-socket joints, which produce so close an
apposition of the anterior free margin of the
mantle with the parts it surrounds, that upon
its contraction, no other outlet, save the funnel,
is left for the expiratory currents. In the Ar-
gonaut the pallial eminence is a round tuber-
cle, below which is a small cavity, and these
are adapted to a cavity and tubercle of corre-
sponding form at the side of the funnel. In

pia, the articular tubercle is elongatéd in the
direction of the axis of the body, and is of an
oval form. In Loligo and Onychoteuthis it is
still more elongated and narrow, and the arti-
cular depression is conformable: in Loligopsis
the corresponding cartilage is no longer sub-

543

servient to an articulation with the funnel, but
is represented by a series of wart-like knobs.

TEGUMENTARY SysteM.—The skin of the
Cephalopods is thin and lubricous, and can
be more easily detached from the subjacent
muscles than in the inferior Molluscous classes.
In the Poulp, Eledone, Argonaut, Cuttle-fish,
and Sepiola, its texture is soft and tender, and
the whole mantle is semitransparent in some |
species, as the Octopus hyalinus; but in the
Calamaries and Onychoteuthides it is thicker,
harder, and more unyielding; it is interesting
to observe that it is in these latter genera that
the epidermoid system is most developed, as
is exemplified in the horny denticulations and
hooks upon the acetabula.

In the Cuttle-fish the suckers are provided
with simple unarmed horny rings. In the
Octopods the epidermis is reflected over the
interior of the suckers without being thickened
into a horny substance at that part. In the
body generally the epidermis is readily de-
tached by maceration, and forms a thick, white,
elastic, semitransparent, external layer.

The colorific stratum of the integument forms,
both in its structure and vital phenomena, one
of the most curious and interesting parts of the
organization of this singular class of animals ;
and the nature of which, when thoroughly un-
derstood, may be expected to elucidate the
mysterious operations of light in producing
and affecting the colours of animals.

This stratum, which is analogous to the
rete mucosum, consists of a very lax and
fine vascular and nervous cellular tissue, con-
taining an immense number of small closed
vesicles, which vary in relative sizes in different
species of Dibranchiata. These vesicles are of
a flattened oval or circular form, and contain a
fluid in which is suspended a denser colouring
matter. The colour is not always the same in
all the vesicles, but in general corresponds
more or less closely with the tint of the secre-
tion of the ink-bag. This, for example, is the
case in Sepiola, in which all the vesicles con-
tain material of the same colour. In Sepia, be-
sides the vesicles which correspond to the ink
in the colour of their contents, there is another
series of an ochre colour. In Loligo vulgaris
there are three kinds of coloured vesicles, yel-
low, rose-red, and brown. In Loligo sagittata
there are four kinds, saffron, rose-red, deep
blue, and light blue. In Octopus vulgaris there
are also four orders of vesicles, viz. saffron, red,
blackish, and blueish. The Argonauta Argo

ossesses vesicles of all the colours which have

een observed in other Cephalopods, and hence
the variety and change of colour which the
surface of its skin presents when exposed to
the light.

These vesicles have no visible communica-
tion either with the vascular or the nervous
systems, or with each other: yet they exhibit,
during the life-time of the animal, and long
after death, rapid alternating contractions and
expansions.* If, when the animal is in a state

* Conf. Dr. Coldstream in Edinb. Journal of
Natural and Geographical Science, yol. ii. p. 297.

544

of repose, and the vesicles are contracted and
invisible, the skin be slightly touched, the co-
Toured vesicles show themselves, and in an in-
stant, or sometimes with a more gradual mo-
tion, the colour will be accumulated like a
cloud or a blush upon the irritated surface. If
a portion of the skin be removed from the
body and immersed in sea-water, the lively
contractions of the vesicles continue; when
viewed in this state under the microscope by
means of transmitted light, the edges of the
vesicles are seen to be well defined, and to pass
in their dilatations and contractions over or
under one another. If the separated portion of
integument be placed in the dark, and exa-
mined after a lapse of ten or fifteen minutes,
all motion has ceased; but the vesicles, when
re-exposed to a moderately strong light, soon, in
obedience to that stimulus, reeommence their
motions. As the vibratile microscopic cilia
have been recently traced through the higher
classes of the animal kingdom, it is not an un-
reasonable conjecture that equally inexplicable
motions of the colouring parts of the integu-
ment may also be detected in other classes
than that in which we have just described them,
and thus a clue may be obtained towards the
explanation of the influence of geographical
position on the prevailing colours of the animal
kingdom.
Besides the colouring matter, another kind of
product is secreted between the corium and
cuticle, viz. the shell: this presents diffe-
rent degrees of development in different genera.
M. De Blainville in France, and Leach,
Broderip, Gray, and Sowerby, among the
able naturalists of our own country, maintain
that the Argonaut shell is not the product of
a Cephalopod, but of some inferior Mollusk,
allied to the Carinariz, whose shell Linneus
indeed placed in the same genus with the
Argonauta, in consequence of the close rela-
tionship subsisting between them, both in form
and structure. The principal grounds for this
opinion are the following. The Ocythoé has
no muscular or other attachment to the Argo-
naut shell. When captured, and placed alive
in a vessel of sea-water, it has been seen vo-
luntarily to quit the shell, and in one instance
without manifesting any disposition to return
to it. In this state, viz. without its shell,
it was described by Rafinesque as a new genus
of Cephalopod under the name of Ocythoée,
and De Blainville, who first recognized this
genus as being founded on an animal identical
with the Cephalopod of the Argonaut, or the
Nautilus primus of the ancients, retained the
name in orderto distinguish the supposed parasite
from the shell which it had, according to this
theory, adopted. Agreeably with the absence
of any natural connexion between the Ocythoé
and the shell in question, is the fact that this
animal is not found in any constant or regular
position in the shell. In most examples we
have found the funnel and ventral aspect of the
body turned towards the external wall of theshell,
as inthe figure (fig. 206). The Cranchian speci-
men figured by Mr. Sowerby was in the same
position, In the specimen which M, De Blain-

CEPHALOPODA.

. a
i

ville* has carefully delineated for bet
, the back of the Ocythoé is next the inv og
uted convexity of the shell, the funnel is ie
towards the opposite expanded concavity, but
turned out of the middle line, and separated
from the parietes of the shell by the retracted
feet. In the figure which illustrates Brode-
rip’s excellent Memoir,t the animal is repre-
sented with the funnel next the involuted crest
of theshell. Inanother specimen in the unique
collection of the same Naturalist, the Cephalo-
pod is retracted on a mass of ova, its arms hud-
dled together, and its funnel projecting from
the middle of one side of the shell; on the op-
posite side numerous suckers are seen expand-
ed and applied to the inner surface of the shell,
demonstrative of the abnormal mode of its ad-
hesion to that body.

Whatever be the position in which the
Ocythoé is found, the whole of the exterior
surface of its mantle is coloured as in the
naked Cephalopods, which seems to indicate
that it has not been permanently excluded from
light by an opake calcareous covering, such as
the Argonauta shell must have formed if it
had been applied to the body of the Ocythoe
ab ovo. What is more remarkable, and con-
trary to the analogy of true testacea, is, that
there is little or no correspondence between the
disposition of the colour of the Ocythoé and
that of the Argonaut shell. The external sur-
face of the skin of the Ocythoé has the same
entire epidermic covering as in the naked
Poulp, yet the Argonaut shell is furnished with
a delicate epidermis in its natural state.

All Mollusks which are naturally pro-
vided with external shells have them for pro-
tecting either a part or the whole of the body; _
and in the latter case the interior of the shell
is always kept clear, that the animal may retire
to it for safety; but this retraction into the hol-
low of the shell is impossible to the Ocythoe,
at least in those numerous cases in which the
shell is found more or less filled ‘with masses
of ova. Other Cephalopods, with external
shells, indubitably their own, as the Pearly
Nautilus, have adequate muscular attachments ;
and it may reasonably be asked does the Argo-
naut afford a valid exception to this rule?

Such an exception indeed it must form if
the shell be really secreted, as the Continuator
of Poli asserts, by the Cephalopod inhabi-
tant; and not only in this particular, but in
every principle which has been established in ~
reference to the relations of a shell to the body
and the reciprocal influences affecting them in ~
the Molluscous classes. \

The naturalists who maintain that the Ce-_
phalopod of the Argonaut and the shell are parts —
of one and the same animal, insist on this unde-—
niable fact, that from the time of Aristotle to thi
present day the Argonaut shell has never been
found with any other inhabitant than the
Ocythoé ; and, what is of more weight, that the
Ocythoé has never been found in au other shell
than the Argonauta. Whereas the Hermut-Crai

* Malacologie, tom. ii. p. 1,
+ Zoological Journal, vol. iv. —

4

CEPHALOPODA. ,

adopts different species as they happen to fall in
his way. And further, that the different species
of Argonauta, as the A. Argo, A. tuberculata,
and A.hians, have each different species of Ocy-
thoé. We may add that the light fragile tex-
ture of the Argonauta shell, like that of Ca-
rinaria, bespeaks a floating oceanic species,
and not a Mollusk that creeps at the bottom,
and therefore the probability is less that its real
inhabitant should have escaped the notice of
the Naturalist, supposing the Cephalopod to
be a parasite.

In the posthumous volume of Poli’s great

work on the Sicilian Testacea, it is stated that
that naturalist watched the daily development
of the ova of an Ocythoé contained in an Ar-
gonaut shell, and that, by means of the micro-
scope, he detected the rudiment of the shell
in the embryo: the completion of the experi-
ment was, however, accidentally interrupted ;
and the figure which the editor Della Chiaje
has published of the ovum, which it was
hoped would have determined the question,
seems to shew the yolk appended to the embryo
instead of the shell.
_ Mr. Gray,* on the other hand, has recently
stated that the nucleus of the Argonaut shell,
or that part which, from analogy, must have
been formed in the egg, is too large to have
been formed in the egg of the Ocythoé. The
arguments drawn from the microscopical exa-
mination of the ova of the Ocythoé before the
commencement of the development of the
embryo, are obviously inconclusive; since,
whatever the subsequent products of the egg
might be, at this period only the granular
and oily particles of the vitelline nidus could
be expected to be seen.

With respect to another argument against
the legitimate title of the Ocythoé to the shell,
founded on the supposed uniform occurrence
of a deposition of eggs in the same shell, we
can adduce three exceptions in which the
Argonaut shell was exclusively occupied by
the Cephalopod ; these specimens were taken
along with several others, by Captain P. P.
King, R.N., from the stomach of a Dolphin,
caught upwards of six hundred leagues from
land, and were kindly presented to us by that
gentleman. In these examples, as in others,

-we were struck with the exact correspondence

between the size of the shells and that of their
inhabitants, every trifling difference in the

' bulk of the latter being accompanied with

proportional differences in the shells which
they occupied. The consideration of all these
circumstances has prevented a satisfactory con-
clusion being formed with respect to this long-
agitated and nicely-balanced question, and we
are compelled to repeat after the Stagyrite, epi
3 yevérews nai cuvavEncews Tou botpanou axpiBas priv
ome Servet Observation of the development
of the Ocythoe until the period when it is ex-
cluded from the egg, would decide the point.

* See Proceedings of the Zoological Society,
September, 1834.

+ “ But as touching the generation and growth of

‘the shell nothing is as yet exactly determined,.”—

Hist. Anim. lib. ix.

545

But this must be done satisfactorily, and with
the requisite knowledge, care, and good faith
on the part of the observer.

Before, however, quitting this subject, we
will mention one example of a naked Ce-
Laieee ih nearly allied to Ocythoé, having
manifested a parasitic propensity similar to
that which is laid to the charge of that genus.
A medical gentleman, (Dr. Moffat, of the
Hon. East India Company’s Ship, Flora,) who
had collected objects in Natural History in
the East Indies, amongst other specimens
brought home an Octopus, which was caught in
the Madras roads in his presence, by means
of a baited hook and line, and, when drawn
out of the water, was found to have its ven-
tricose body firmly imbedded in a ghee-bowl,
(one of the small round pots in which the fluid
butteris brought on board ship,) which had been
thrown overboard. The Doctor disengaged the
Cephalopod from the bow! before placing it in
spirits, and when we related to him the interest
which the fact possessed in consequence of the
problematic nature of the Argonaut shell, of
which he was not before aware, he regretted
much that he had not preserved the Octopus
in the singular domicile which it had chosen.
Another instance of the parasitic appropriation
of a dwelling-place by a Poulp is related by
M. Desjardins, in the Report of the Natural
History Society of the Mauritius ; he found an
Octopus Arenarius in the shell of a Dolium.

The parasitic occupation of shells by the
Octopi for the purpose of depositing the ova in
them was not unknown to Aristotle. Kat
dmrorinres 6 padv TonuTous els TAG Darauac hi ele nepasesov
iT a Are xotrov Suoiov, &e. “ And the Polypus
oviposits in cavities or in shells, or some such
hollow places.” *

To return to the shells of the Dibranchiate
Cephalopods; these, then, with the doubtful
exception of the Ocythoé, are always internal,
and either camerated and siphoniferous, or
laminated and more or less rudimental,
and concealed within the substance of the
mantle.

In Octopus and Eledone the traces exist in
the form of two small amber-coloured styli-
form bodies, lodged loosely in capsules, (im-
bedded in the sides of the mantle,) and ex-
tending downwards from the insertion of the
shell muscles, close to the base of the bran-
chie. When the capsules are laid open, the
styles frequently fall out in pieces, being of a
friable texture. In the Octopus the styles are
straight and elliptical; in Eledone they are
largest at their upper extremities, and become
filiform as they pass in a curved direction
downwards.

In all the Decapoda in which the shell is
rudimental, it is represented by a single piece
lodged in the middle line of the dorsal region
of the mantle. It is of a horny texture in all
the genera except the Sepia, and has generally
more or less the form of a feather, as in the

Calamary (fig. 228), or of a straight three-
edged sword.

* Hist. Anim. v. c. 16.

546

According to Aristotle the hard dorsal body
of the Cuttle-fish was called by the Greeks
‘sepion,’ that of the Calamaries ‘ xiphos.’”*
In Sepiola and Rossia the gladius does not
reach half-way down the back, beginning at
the anterior margin of the mantle, which in
the latter genus is free. In Loligopsis, Cran-
chia, Onycoteuthis, and Loligo, it extends
the whole length of the posterior part of the
mantle. In Sepioteuthis it rivals in breadth
the Sepium or Cuttle-bone, but is horny and
elastic, as in the Calam In the latter the
gladius is multiplied by age, and several are
found packed closely one behind another in
old specimens.

Fig. 229.

Fig.228.

9)

Va
Gladius of the Rudimental Shell of the
Calamary. Cutile-fish.

The Sepium or Cuttle-bone (fig. 229) isa
well-known substance, and formerly figured in
the Materia Medica as an antacid. It is a
light cellular calcareous body, of a peculiar
form and structure; and, as it is confined ex-
clusively to the genus Sepia, its presence alone
serves to characterise that section of Cepha-
lopods. Its form is an elongated oval, de-

pressed, convex on the dorsal surface, partly.

convex and partly concave on the opposite
side: it terminates posteriorly in a very thin,

* SCOTS ply oby onwia, nal ry TevOid xal re TevOw
ivres Ect Ta crepes Ev Tie Mpaver TU wamatos, & xa-
rodeos +d pty camiov, TedE Lipos. Sub dorso firma

ars Sepie Loligini ac Lolio continetur ; illius sepium,
orum gladium vocant.— Hist. Animal., lib. iv., c.1.
12mo. Ed. Schneider.

CEPHALOPODA.

dilated, aliform margin (a, a), partly calca-.
reous and partly horny, which becomes nar-
rower as it advances forwards, and is gradually
lost in the sides of the shell. As this margin
is inclined towards the ventral aspect, it pro-
duces at the posterior and ventral side of the

shell a wide and shallow concavity, comparable _

to the chamber of the Nautilus shell which
protects the body of that species: if the free
margin of the sepium were in like manner
poe beyond the een deposited
ayers, it would advance from the posterior and
lateral aspects of the animal, and cover the
ventral surface, as in the Nautilus, leaving the
convexity produced by the chambered portion
projecting into the back. The thickened part
of the sepium (6) which retains that situation,
is in fact composed of a series of thin parallel
calcareous plates, successively deposited and
extending obliquely forwards from the ventral
to the dorsal surface : the last formed plate is
the most internal and the broadest, but not the
longest also, as in the Nautilus ; its develop-
ment being limited to the anterior part of the
shell, so that the previously deposited layers
appear successively behind it forming irregular
sinuous transverse strie (c). The intervals of
the plates are occupied by crystalline fibres,
passing perpendicularly from one layer to the
other: A is a magnified view of this structure.
At the posterior part of the sepium, a little
anterior to the thin margin, a pointed hooked
process projects backwards: this differs in size
and shape in different species of Sepia; but it is
always characteristic of the peculiar production
which has been described, and has served to
identify some doubtful fossils.

As our present observations are limited to
the recent species of Cephalopoda, we pass
over the Belemnites, which are fossil internal
shells of extinct animals of this order, to speak
of that of the Spirula. This is a small recent
Cephalopod, respecting the precise form and
organization of which nothing is yet satis-
factorily known. The only entire specimen
which has been brought to Europe was taken
by Péron, a French Naturalist, as it floated
dead in the Tropical Ocean, between the Mol-
luccas and the Isle of France; it has been de-
scribed and figured by Roissy, Péron, and
Lamarck ; but both the figures and descrip-
tions of these authors differ, and the specimen
now no longer exists to determine the accuracy
of either of the accounts.
ever, in stating that part of the shell was
concealed within the body of the animal; and
this fact is confirmed by a mutilated specimen
in our own possession, and by one in a similar
condition in the British Museum.

The shell of the Spirula (fig. 230) is about
an inch in diameter, .

symmetrical, con-
voluted om one
plane, with the

whorls disjoined :
it is composed of a
succession of small
regularly formed

‘

Shell of the Spiruta

chambers, separated by partitions (4, a), which !

All agree, how- |

a ee.

‘
a a ls

Ee

aa oe

= Sct Sra a Sees

CEPHALOPODA.

are concave towards the outlet of the shell,
and are perforated by a siphon (6), the mem-
branous tube of which is protected by a series
of funnel-shaped calcareous sheaths (c), which
are continued from the hole of one septum
into that of the next, throughout the shell.
The shell is white, lined with a nacrous layer
within, and partially covered bya straw-coloured
epidermis without. The organization of the
Spirula may be expected to be in some respects
intermediate to the Nautilus and Sepia, and an
opportunity of investigating its internal struc-
ture is therefore highly desirable. According
to Lamarck the animal is a Cephalopod with
eight feet and two tentacles, like a Cuttle-fish,
all provided with suckers; the body shaped
like a purse and terminated behind by two
lobes.

Although the siphoniferous shells are not
confined to the Tetrabranchiate Order, yet it is
in this division, as in the Pearly Nautilus for
example, that we find this singular testaceous

roduction to have arrived at the maximum of
its development: it is covered by an epidermis,
and, in the living animal, is also probably
partially overlapped by a reflected portion of
the thin and extensible mantle; but no part of
it is buried in the substance of the animal,
whose entire body, on the contrary, is inclosed
in the last large expanded chamber. The re-
lative position of the soft parts to this cham-
ber we had not the means of determining from
the specimen dissected by us, as this had been
removed from its shell by Mr. Bennett, its
fortunate captor, before it was placed in spirits.
According to this able naturalist’s statement,
however, the ventral surface of the body and
funnel was applied to the concavity of the
outer Sander wall of the chamber; and the
concavity behind the cephalic disk was adapted
to the involuted convexity of the shell, and
abutted against the ridge which rises from that
part.* The camerated portion of the shell,
according to Mr. Bennett, contained water or
a liquid; but the size, condition, and con-
tents of the membranous tube were not ob-
served by him. The external form of the soft
parts supported Mr. Bennett’s account of their
relative position to the shell; but some cir-
cumstances 4 oe to militate against the
fluid nature of the contents of the deserted
chambers. In the description of this spe-
cimen, we accordingly stated our belief that
the chambers are naturally filled by a gaseous

‘exhalation or secretion of the animal, and that

the liquid is contained in the dilatable siphon
which is extended from the posterior part of
the animal’s body, and passes through the

central apertures of the different septa of the

shell. From the communication which this
siphon has with the pericardial cavity, it can be
influenced, as to the quantity of fluid which it

* M. De Blainville, in a learned Memoir on the
Structure of the Shells of Spiruala and Nautilus,
States his opinion that the true position of the ani-
mul of the latter shell is the reverse of that de-
scribed above: this opinion has been adopted by

some Naturalists of this country, but the analogies
by which it is endeavoured to be supported are too

remote and vague to enforce conviction.

547

contains, by the actions of the Nautilus itself. A
pneumatic and hydraulic apparatus for effecting
the rising and sinking of the shell and its in-
habitant is thus established, and Dr. Hooke’s
ingenious conjecture of the use of the camerated
part of the shell is confirmed ;* but the relative
positions of the gas and water would, accord-
ing to the above opinion, be the reverse of what
Parkinsont supposed them to be. The full
development of the theory of chambered shells,
considered as hydrostatic instruments, is, how-
ever, in abler hands than ours; and the reader
wil! be gratified to learn that it forms the sub-
ject of a portion of the forthcoming Bridge-
water Treatise by Dr. Buckland.

Nervous System.—In tracing the develop-
ment of the Nervous System through the
Heterogangliate or Molluscous type of Orga-
nization, we find in the Gasteropodous genera
which approach nearest to the Cephalopodous
or highest division, that the ganglions which
are concentrated about the head, are arranged
in three groups: one, which is supracesopha-
geal, supplies the sentient organs, as the eyes
and feelers; a second, which is subesophageal
and anterior, supplies the buccal apparatus ;
a third, which is subcsophageal and pos-
terior, is the centre from which the sensitive,
motive, and plastic nerves of the trunk ori-
ginate. The anterior or buccal ganglions are
united together, and to the cerebral ganglions,
forming a nervous collar around the esophagus ;
a similar collar is formed by the corresponding
intercommunicating chords of the posterior
subcesophageal ganglia.

In the Cephalopods the nervous system is
disposed on the same general plan, but the
nervous substance is accumulated in a greater
degree at the different centres of radiation,
according to the superior development of the
parts that are to be supplied therefrom.

In the Tetrabranchiate Order the principal
parts superadded to the structure which we
observe in the Gasteropodous Mollusk are those
locomotive and prehensile organs which sur-
round the buccal apparatus; and the chief
modification of the nervous system is therefore
seen in the enlargement of the oral ganglia
and collar, and their close approximation to
the cerebral ganglion. ‘This part is compara-
tively little advanced, since the organs of
sense which it immediately supplies, retain
the same simple structure as in the inferior
class of Mollusks, and are only augmented
in bulk. The brain therefore is represented
by a thick round tranversely extended chord
(1, fig. 231), communicating at its extremi-
ties with the anterior and posterior cesopha-
geal collars (3, 4), and with the small
optic ganglions (2, 2), which supply the sim-
ple pedunculated eyes. Four small pairs of
nerves (5) also pass from the suprawsophageal
band to the fleshy mass ee the man-
dibles. The cranial cartilage seems in the
Nautilus to be principally developed with re-
ference to the strong muscular masses to which

* Philosophical Experiments and Observations,

p- 307.
+ Organic Remains, vol. iii. p 102.

584

Nervous System of the Pearly Nautilus.

it affords a fixed point of attachment, and is
not extended upwards so as to inclose the
brain: this part is defended by a strong mem-
brane which loosely surrounds it; but the ex-
tremities of the transverse band, the optic gan-
glions, and the anterior esophageal collars rest
in grooves of the cranial cartilage.

The nerves which arise from the anterior
collar are very numerous: the larger branches
(6, 6) enter respectively the roots of the ten-
tacles which are lodged in the digital pro-
cesses: the ophthalmic tentacles are also sup-
plied from this source (5*); no lateral con-
necting filaments are found between these
nerves, corresponding to those which associate
the corresponding nerves of the Poulp for the
simultaneous action of the parts they supply.
Below the digital nerves small nerves are
given off (12), which enter the external labial
processes, and penetrate in a similar manner
the roots of the tentacles which are there

CEPHALOPODA.
Fig. 231.

:

lodged. The internai labial processes are,’

however, supplied in a different manner: a
larger nerve (7, 7) comes off on each side near
the ventral extremity of the ganglion, and after
a course of half an inch swells out into a
flattened ganglion* (8, 8), from which nu-
merous filaments (9, 9) extend into the sub-
stance of the process, and are continued into
the tentacles as in the preceding case ; a larger
twig (10) inclines inwards and distributes fila-
ments to the olfactory lamine. The infundi-
bular nerves (11) come off near the lower part —
of the anterior collar. a

From the ganglions composing the posterior —
collar (4, 4) arise numerous nerves of a flat- —
tened form, (13, 13,) which pass in a radiated —
manner to the inner sides of the shell-muscles"

* These ganglions I believe, from subseqt
examination, to have been also connected with a
nervous twig from the fleshy mass of the mouth,
derived from the supra-cesophageal ganglion,

CEPHALOPODA.

which they perforate, but there are no columns
prolonged backwards from the lateral parts of
the brain to form pallial ganglia as in the
higher Cephalopods; the structure and func-
tions of the cloak to which these ganglia are
Subservient, not being enjoyed by the shell-
clad Nautilus. The nerves corresponding to
the large visceral nerves of the Dibranchiates
are, however, proportionally occa 3 for in
the organs of plastic life the Nautilus is upon
an equality with its naked congeners. These
nerves, which combine the functions of the
sympathetic and par vaguin, consist of a large
pair derived from the lower part of the pos-
terior cesophageal collar, and extending back-
wards on each side of the vena cava; and of
smaller twigs (17) coming off between the
origins of the preceding nerves, and forming a
lexus upon the ietes of the vein. The
arger chords swell into ganglions at the termi-
nation of the vena cava, (16, 16,) and send off
ramifications to the branchiz, (15, 15,) the
contents of the pericardium, and the viscera of
digestion and generation.
In the Dibranchiate Cephalopods which
possess instruments for varied and active loco-
motion, where the visual organ is of large size,
and attains a complexity of structure equal to
that of the Vertebrate animals, where a distinct
acoustic organ is developed, and where the
whole surface of the body is the seat of sensi-

Fig. 232.

Nervous system of the Cuttle.fish.

549

bility, the centre of nervous impression and
volition is proportionally developed, and exhi-
bits the highest conditions which the brain pre-
sents in the Invertebrate series of animals.

Except in some of the smaller species, as
the Sepiola, in which the surrounding sub-
stance still retains the consistency of a mem-
brane, the brain, together with the anterior
and posterior cesophageal collars, is entirely
surrounded by a thick cartilage. The portion
of esophagus which is thus enclosed is sepa-
rated from the surrounding medullary matter
by a thin layer of softer substance. e cere-
bral cavity is larger than the brain itself, and
the intervening space is filled with a gelatinous
fluid. In the Cuttle-fish the supra-cesophageal
mass is transversely shortened, as compared
with the Nautilus, and supports a smooth,
rounded, heart-shaped medullary mass, slightly
divided into two lateral lobes by a mesial lon-
gitudinal furrow (1, fig. 232); from the lower
and lateral parts of this body proceed the broad
bands of cerebral substance which afterwards
dilate into the large reniform optic ganglions
(2, 2); upon each of these bands is placed a
small spherical medullary body (k, k). These
bodies, which we first discovered in the Sepia,
we have since ascertained to exist in Loligo.

From the anterior apices of the cerebral
lobes small nerves are continued, which almost
immediately dilate into a round flattened gan-

glion (a, fig. 233); this is closely
applied to the back part of the fleshy
mass of the mouth above the pharynx;
it sends off nerves to the oral appa-
ratus (7,7, fig. 233), and two fila-
ments descend and form a pair of
small closely approximated ganglions
(8, 8, fig. 232) below the mouth,
analogous to the labial ganglions of
the Nautilus.

From the inferior, lateral, and an-
terior parts of the brain two large
chords (k, fig. 238) descend, and
unite and dilate below the cesopha-
gus to form the anterior subcso-
phageal ganglion, or pes anserinus of
Cuvier, from which the nerves of the
feet and tentacles arise. Two still
larger bands (J, fig. 233) descend
from the brain behind the preceding
to form, by a similar enlargement and
union, the posterior cesophageal gan-
glionic collar. From a comparison
of these with the corresponding gan-
glions of the Nautilus, it will be seen
that by their approximation in the
transverse direction the distinction
of the ganglions at the lower part
of the collar is lost; and a corre-
sponding approximation in the antero-
posterior direction, being accompa-
nied by an additional accumulation
of nervous substance, has produced
a blending together of the four gan-
glions into one large continuous sub-
cesophageal mass. The portions of
this mass corresponding to the four
ganglions and double cesophageal

550

collar of the Nautilus, are notwithstanding
indicated in a manner not to be mistaken,
by the origins of the nerves which it sends
off, and by the chords which bring it into
communication with the cerebral mass above.

We shall now briefly mention the points in
which the brain in other Dibranchiata differs
from what we have described, after careful
examination of this part in the Cuttle-fish. In
the Poulp, the brain or supra-cesophageal mass
is divided, according to Cuvier, into two parts,
an anterior (a, fig. 233), which is of a flatter
and squarer figure and of a whiter colour,
compared by Cuvier to the cerebrum, but
which seems to be the pharyngeal ganglion
more closely approximated to the brain than
in the Sepia: and a posterior globular mass
(b), of a grey colour, which he compares ‘to
the cerebellum ; the optic nerves (c) are much
smaller than in the Cuttle-fish, and do not
support the small spherical bodies which exist
in the Cuttlefish and Calamary.

Brain and nerves of the Octopus vulgaris.

The brain of the Argonauta does not present
a rounded form above, but when seen from this
aspect, is composed, as in the Octopus, of an
anterior white oblong band, flattened trans-
versely, and of a posterior raised convex semi-
lunar mass, which terminates behind in a semi-
lunar border, the extremities of which are con-
tinued directly to form the posterior collar of
the cesophagus.

The nerves of the arms proceed from the
anterior and inferior subcesophageal ganglions
(d, fig. 233), corresponding in number to the

-CEPHALOPODA.

s supply, viz. eight in the Octopodas
end fing ie Danigods But, according to
Rathké, the Loligopsis offers an exception, the
nerves of each lateral series of arms belie con-~
tinued for a short distance from the brain as a
single pair. In the Poulp, the eight nerves
(e, e, fig. 233) glide along the inner surface of
the basis of the feet, which they penetrate re-
spectively, running with the great artery in
their substance, and forming, as Cuvier has
described, a series of closely approximated
ganglions, corresponding to each pair of suck-
ers, and sending off radiated filaments. In the
Genus Eledone, where the arms are narrower,
and the suckers are arranged in a single series,
the ganglia are relatively smaller.

In the peduncles of the Decapoda the nerves
are continued of a simple structure as far as the
acetabuliferous extremities, where they become
enlarged and gangliated.

Before forming the ganglionic enlargements
in the ordinary arms, each brachial nerve gives
off two large chords, one to each side, which
traverse the fleshy substance of the base of the
feet to join the two corresponding branches of
the contiguous arms ; the eight nerves are thus
associated by a nervous circle (f, f, fig. 233),
which subdivides into two, and forms a small
loop at each chord.

nerves of the funnel, from the nervous sub-
stance that effects, as it were, the junction of the
two cesophageal collars below. Next arise the
large visceral nerves (14, fig.232,233), which,
after distributing filaments to the muscles of

_ the neck, descend parallel and close to one

another behind the vena cava, give off from
their inner sides the small filaments which con-
Stitute the plexus upon the vein; they then
diverge from each other towards the root of
each gill, where they divide into three princi-
pal branches: one of these dilates into an
elongated ganglion (c, fig. 232), and enters the
fleshy stem of the branchia; the second de-
scends to the bottom of the sac; the third
passes to the middle heart. The plexus pre-
viously formed upon the vena cava receives
additional filaments from the two latter bran-
ches; and a large sympathetic ganglion is
formed, which is attached to the parietes of the
stomach, near the pyloric orifice.*

The most important and interesting nerves are
the two large ones,(13, 13, figs. 232, 233,) which
arise from the posterior and lateral surface of
the subcesophageal mass, and extend outwards,
downwards, and backwards, perforating the
shell muscles, and forming upon the inner
parietes of the mantle the large stellated gan-
glion (d, d, fig. 232), from which the nerves of
the mantle are derived. In the Octopoda the

* See Brandt Medicin. Zoolog. a.a. 0. S. p.309,
tab. xxxii. fig. 23, who first described this ganglion
in the Sepia, and Jacob’s figures of the Anatomy of
the Octopus Vulgaris, pl. xv. fig. 7; pl. xiii. figs.

ys in Ferussac’s Monograph on Cephalopods,
ol.

St a

=
j=

TR OS =

2S

CEPHALOPODA.

nerve terminates in this ganglion, (v, v, fig.
226,) from which about twenty branches radiate
to the mantle; but in the Decapoda, in which
lateral fins are superadded to the trunk, it pre-
viously divides into two large branches. Of
these the external alone produces the ganglion
from which the sensitive nerves are distributed
in a radiated manner, as in the Poulp; the other
division (e, fig. 232), after having bet joined
by a branch (/') from the ganglion, pierces the
fleshy substance of the mantle, and ends ina
diverging series of twigs appropriated to the
muscles of the fin (g). In proportion as the
trunk of the Cephalopod is elongated, these
branches become more parallel in their course,
and dorsal in their position.

The anterior part of the mantle is supplied
by small nerves, having a distinct origin from
the posterior subcesophageal mass, above the
great moto-sensitive chords.

With respect to the parts of the central axis
of the nervous system of the Vertebrata which
are So antes by the structures above de-
scribed, we may reasonably infer from the fact
that the supracesophageal mass in the Dibran-
chiate Cotdnlopois, especially the posterior
division, is principally in communication with,
and owes its superior development chiefly in
relation to the complex organs of vision, that it
is analogous to the optic lobes or bigeminal
bodies. For if it be regarded, as Cuvier sup-
poses, as the cerebellum of the vertebrate brain,
we have then to reconcile the anomaly of this
ot being the seat of origin of the optic nerves.
‘The constancy, again, of the optic lobes in the
vertebrate series, and their priority of develo
‘ment to the cerebellum, leads naturally to the

ctation that these would form part of such
a brain as the highest invertebrate animal is
endowed with. The smaller portion of the
brain of the Poulp anterior to the optic lobes
appears to represent an olfactory lobe. With
respect to the inferior cesophageal mass, as it
gives origin to the auditory and respiratory
nerves, and those two large moto-sensitive co-
lumns, which evidently represent, by their
structure and position, the spinal cord of the
Vertebrata, we consider it as fulfilling the
function of the medulla oblongata, and to be
the part of the nervous centre which is most
intimately connected with the vital energies of
the animal.*

Orcans or Sensz.—The Cephalopodous
‘class is the only one in the Invertebrate series
in which distinct organs of sight, hearing, smell,

-and taste, have been detected, although the en-

—— of these senses is evidently byno means
limited to this class. Considerable differences,
however, present themselves in the relative
‘complexity, and even as to the existence of
the different Organs of Sense in the two orders
of Cephalopods: thus, of the senses which
relate to distant objects, the Organ of Hearing
. to be wanting in the Nautilus, and

the Organ of Vision is comparatively imperfect,

* See vol. iii. pt. 1, p. 187. Physiological Cata-
logue of the Museum of the Royal College of Sur-

-geons, 4to. 1835,

551

while those which take cognizance of proximate
objects are more distinctly and extensively
developed.

Organ of Sight-—In the Nautilus the eyes
are supported on short pedicles which project
outwardly from the sides of the head. They
are of a spherical form, slightly flattened ante-
riorly ; are large as compared with the
dunculated eyes of Gasteropods, but are of
small size as compared with the complex visual
organs of the Dibranchiates. They presented,
in Mr. Bennett’s specimen, the simplest con-
dition of an organ of vision, consisting only
of a darkened globular cavity or camera ob-
scura, into which light was admitted bya single
orifice, and a nerve expanded at the opposite
side to receive the impression; the mechanism
for regulating the admission of the impinging
rays was wanting, and every trace of that
which modifies their direction had disappeared.
The form of the eye was maintained by a tough
unyielding sclerotic coat (k, fig. 231), which
became thinner towards the anterior part of the
eye, where it was perforated by a circular aper-
ture less than a line in diameter(m). The nerves
continued from the small oval optic ganglion (2)
expand, and immediately line the sclerotic as far
as the middle of the globe, forming a strong re-
ticulate retina (0), which, together with the rest
of the cavity, is lined by a black pigment (n).
There was no appearance of vitreous humour
or crystalline lens; but both parts would no
doubt be found to exist in the recent state.

In the Dibranchiata the eyes are sessile,
but in some species project beyond the sur-
face of the head more than in others; their
complicated structure is truly one of the most
remarkable features of the organization of this
singular class.

The eyeball in the Cuttle-fish is inclosed in a
capsule consisting posteriorly of a thick carti-
lage (a, a, fig. 234), in its lateral circumference

Section of the Eye of the Cuttlefish.

of a strong white fibrous membrane (6, b), and
anteriorly of the cornea (0).

The whole of the inner surface of the cap
sule is lined by a thin serous membrane, as far

552.
as the margin of the thick posterior cartila-
ginous orbit, to which it is attached, and is
thence reflected forwards (c, c) upon the mus-
cles of the eye-ball, also upon the long narrow
anterior and inferior ocular cartilage (d,d), and
upon the exterior fibrous layer of the sclero-
tica; it is reflected inwards over the anterior
thickened margin of the sclerotica, where the
large anterior aperture of that membrane re-
mains unclosed by the cornea, and consequently
— along its inner surface like the. mem-

rane of the aqueous humour ; it seems to us,
however, not to pass over the anterior part of
the capsule of the crystalline lens, but into the
groove (p, p) which divides that body into two
parts. The serous layer above described can-
not be detached from the cornea, but ceases to
be demonstrable as a distinct membrane where
the external fibrous coat is attached to the
cornea. The space between the eye-ball and
its capsule, which is thus circumscribed, is
filled with a watery fluid, which is most abun-
dant in the Calamaries. The cornea is sepa-
rated by the same fluid from the eye-ball; but
its tension and slightly convex figure is main-
tained by it, as by the aqueous humour in the
eye of the vertebrate animal. The motions of
the eye-ball are facilitated by the secretion of
the serous sac, as the movements of the heart
in the pericardium, and in other instances in
which serous membranes are developed.

The membrane, of which we have just de-
scribed the reflections and extent, is regarded
by Cuvier as analogous to the tunica conjunc-
tiva, but a difficulty arises in this mode of
considering it, in consequence of the position
of the cornea (0), which, in its structure and
connection with the integument, bears a close
analogy to the cornea in Fishes. The charac-
teristic difference which the cornea presents in
the latter class, as compared with that of the
Cephalopoda, is its adhesion to the margins
of the anterior aperture of the sclerotica, by
which the anterior chamber of the eye is
limited to a very small space; while in the
Sepia it would seem as if the membrane circum-
scribing the anterior chamber had over-passed its
usual bounds in consequence of the absence of
any such adhesion between the cornea and sclero-
tica. When we consider the nature of the
membrane in question, and the relations of
the fluid it secretes to the cornea and crystal-
line, should we not be justified in considering
it, notwithstanding its excessive development,
as analogous rather to the membrane of the
aqueous humour, than to the conjunctiva,
the ratio of the development of which is as
that of the eye-lids or folds of membrane ex-
ternal to the cornea, and of which we have
only a slight rudiment in the Sepia? (v.)

The space between the cartilaginous orbit
and the posterior part of the eye is circum-
scribed by a membrane (e, e) which has the
character rather of a condensed layer of cellular
tissue than of a true serous membrane. In
this space is contained the optic ganglion (f),
its filaments (g), and the surrounding soft white
substance (h), by some considered of an adi-
pose, by others of a glandular nature. This

CEPHALOPODA.

cavity is proportionally larger in the Octopus.
than in the Sepia. BAR y

The eye-ball of the Cuttle-fish is an irregular
s harcite flattened in the direction of its axis.

e vertical diameter is less than the horizontal, —
but both exceed the diameter of the axis.. The
eye-ball is remarkable in all the Dibranchiata_
for its considerable development as compared
with the size of the body; it is proportionally
largest in the Calamaries, and smallest in the.
Octopods. .

The exterior membrane covering the ante-
rior part of the eye-ball (7) receives the inser-.
tions of the muscles of the eye, and seems as
if it were formed by their aponeurotic expan-.
sions ; it lies immediately beneath the reflected
layer of the serous covering, is of a soft texture, -
and has a pinkish colour with a glistening
silver lustre; in the Poulp it is spotted like
the skin. The entire eye-ball is surrounded
by a second layer of membrane (k, k), having
a similar texture and appearance; these are
analogous to the exterior or fibrous layers of
the sclerotica in the eyes of Fishes. We next
find a cartilaginous layer (J, /) corresponding to
the internal cartilaginous sclerotica of the Pla-
giostomous Fishes. This coat is very thin,
and almost membranous posteriorly, where the
fibrils of the optic ganglion penetrate it, and
where it presents a cribriform surface of consi-
derable extent, in which it may be observed
that the orifices of the sieve are of consi-
derable size, and not very close together.
Anterior to the cribriform surface the cartila-
ginous sclerotica increases in thickness, but
more so on the lower than the upper side
of the eye, and about the middle of the eye-
ball it terminates in a slightly thickened mar-
gin. <A layer of fibrous membrane (m, m)
is continued from this margin, along with
the external fibrous layer (/), and assists in
forming the. soft thick anterior part of the
sclerotica, which forms the circumference of the
pupillary aperture (7), or that by which light is
admitted to the cavity of the eye. The supe-
rior part of this aperture is encroached upon
by a bilobed curtain-like process, which we
have observed to present a semi-transparent
texture in the eyes of some Cuttle-fishes, as if it
were an abortive formation of a sclerotic cornea:
in position it resembles the curtain-like process
depending from the iris of the Ray. |

The inner surface of that part of the sclero
tica which lies anterior to the lens is lined with
a dark pigment.

The tunic which immediately lines the car-
tilaginous sclerotic is not, as in Fishes, a —
membrana argentea, or a vascular choroid,
but consists of an expansion of the ner-
vous fibres which are given off from the optic —
ganglion, connected together by a vascular
and cellular tissue (0, 0). The ganglion does
not resolve itself into these fibres uniformly
from the circumference to the centre, but sends
them off from its exterior surface only, so that,
on making a section of the part, the centre of
the ganglion presents a homogeneous pulpy
texture, separated by a distinct external layer
from the origins of the fibrils, as in the figure, f-

a

.

CEPHALOPODA.

The fibres, after perforating the cartilaginous
sclerotica, and expanding into the post-pig-
mental retina, extend towards the groove of the
crystalline, in a direction chiefly parallel to
one another, the tunic formed by them be-
coming thinner as they advance forwards ; this
is joined by a thin membrane, which extends
from the anterior margin of the cartilaginous
sclerotica, and forms, with that membrane, a
ciliary plicated zone (p,p, where it is repre-
sented as left entire,) which penetrates the
groove of the lens. The outer surface of this
thick nervous tunic is fibrous and fiocculent,
and connected to the sclerotica by a fine cel-
lular tissue: the anterior or internal surface is
perfectly smooth.

‘This surface of the nervous tunic is co-
vered by a tolerably consistent layer of a dark
gece pigment (g). Cuvier, who re-

s the preceding tunic as the only part
analogous to the retina in the eye of the Ce-
pres, expresses his surprise that this black
ayer is not an insurmountable obstacle to
vision ;* and different theories have been
15 he to account for the singular position

f the pigment on that supposition. In the

eyes of different Sepie which we had immersed
in alcohol preparatory to dissection, we have,
however, invariably found between the pig-
ment and the hyaloid coat a distinct layer of
Opaque white pulpy matter (7), of sufficient
consistence to be detached in large flakes, and
easily preserved and demonstrated in prepara-
tions. We confess, however, that we can
discover no connection between this layer and
the thick nervous expansion behind the pig-
ment; but, nevertheless, we cannot but regard
it as being composed of the fine pulpy matter
of the optic nerve, and as constituting a true
pre-pigmental retina.
_ The hyaloid coat, which is remarkably dis-
tinct in all the Cephalopods, completely sepa-
rates the vitreous humour from the internal
white layer above described. It is perfectly
transparent, and, though thin, is strong. The
vitreous humour does not lose its transparency
when preserved in alcohol.

The crystalline lens is of large size, and is
composed of two completely separated portions :
the anterior moiety is the segment of a larger

here, but forms the smaller part of the lens ;
the posterior is a segment of a smaller sphere,
and forms the larger part of the lens. Two
layers of transparent membrane are continued
from the ciliary body between these segments.
Each of the segments is composed, as in the
lens of higher animals, of concentric lamine,
which become denser towards the centre, where
the nucleus resists further unravelling of its
structure. It is of a brown colour, and pre-
serves its transparency in alcohol. The lamine
are ip of denticulated fibres; but the
minute description of their texture and arrange-
ment will be given in another place.

The white substance (h) which surrounds
‘the optic ganglion is divided into lobes, but

__* «On ne congoit pas comment elle n’est pas un
obstacle insurmontable a la vision.”—Mém. sur le

Poulpe, p. 39.

503

exhibits no distinguishable secerning structure ;
the bloodvessels of the eye ramify between
these masses ; the smaller twigs accompany the
nervous fibrils; the larger ones pass forwards
to the anterior soft margin of the sclerotica.
We regard this substance as analogous to the
so-called choroid gland in the eyes of Fishes.
Cuvier assigns to it the function of defending
the nervous ganglion and fibres from surround-
ing pressure ; and this is most probably the
true final intention of the substance, since it
intervenes between the ganglion and the mus-
cles of the eye-ball.

Of these we find three straight muscles and
one oblique. The inferior rectus of each eye
arises from a small transverse tendon which
adheres to the inferior and anterior border of
the cranial cartilage, to which it runs parallel,
and is attached at its two extremities to the
muscles above mentioned, and also to the base
or root of the anterior elongated cartilaginous
orbital plate. z

A second straight muscle arises from the
posterior margin of the elongated cartilage
above mentioned; its fibres run parallel to
those of the preceding, and are inserted into
the external sclerotica. Both these muscles are
thin, broad, and fleshy.

The oblique muscle arises from the inferior
and posterior margin of the external orbital car-
tilage, and expands, as it proceeds outwards
and forwards, to terminate in the external mem-
branous sclerotic. ‘These muscles are readily
exposed by dissecting away the orbital capsule
from the under part of the eye-ball.

A short and strong superior rectus, the ten-
don of which is continuous with that of the
opposite side, is inserted into the upper part of
the sclerotic.

A few observations remain to be made on the
structures defending the anterior part of the eye-
ball. The cornea of the Cuttle-fish is appa-
rently entire; it is thickest at its superior mar-
gin (¢), where it is implanted in a groove of
the integument; it becomes gradually thinner
towards the lower margin, where it is over-
lapped by the rudimental eyelid (v). This
consists of a narrow semilunar fold of inte-
gument, the concavity of which is directed
upwards and a little backwards.

In the small Cephalopod which Captain Ross
discovered in the Arctic Ocean, and which has
been named after that distinguished and scien-
tific navigator,* the cornea is defended by a
continuous circular fold of integument, which
can be completely closed by an orbicular
sphincter in front of the eye, a structure which
is probably required in this species in order to
protect the cornea against the spicule of ice
with which its native seas abound, especially
in. the summer or thawing season. In the
Calamary, on the other hand, there is no tegu-
mentary fold. Upon carefully inspecting the
cornea of the Cuttle-fish, a minute foramen
will be seen near the inner or anterior margin
of the cornea, covered by the upper extremity
ofthe fold ofintegument. The aperture leads ob-

* See Appendix to Sir John Ross’s Voyage, 4to,
p- xii, pl. B. Cc,
20

3
554
liquely downwards and backwards, and if air
be blown or fluid injected through it, the large
cavity surrounding the anterior part of the eye-
ball will be distended, and the cornea ren-
dered convex. In the Poulp the corresponding
aperture (0, fig. 216) is somewhat larger, and
situated more in the axis of vision : its inferior
and posterior margin is extended beneath the
opposite margin, so as to form a semi-transpa-
rent curtain behind the external opening. In
the common Calamary and the Onychoteuthis
the corneal perforation is still larger, vertically
oblong, and through it the capsule of the cry-
stalline lens, which projects through the scle-
rotic aperture, is immediately exposed to the
external medium.

Organ of Hearing.—This organ has hitherto
been found only in the Dibranchiate division
of the Cephalopods. It consists, as in the
Cyclostomous or lower organized cartilaginous
Fishes, of an acoustic vestibule, containing a
limpid fluid and a calcareous body or otolithe
suspended in a delicate sacculus to the filaments
of the auditory nerve, but without the semi-
circular canals, cochlea, or other parts which
progressively complicate the Organ of Hearing
in the higher animals.

- The vestibular cavities (a,
a, fig. 235) are situated, not
at the sides, but at the base
of the cranium in that thick
and dense part of the carti-
lage which supports the sub-
cesophageal cerebral masses.
In the Cuttle-fish the cavities
are of a sub-quadrate form,
separated only by a thin septum (c) ; and they
are every where closed, except at the entrance of
the nerve. From their inner surfaces project
several obtuse moderately elongated processes
(6, b, fig. 235), of a soft elastic texture, which
support the central sacculus (d) and otolithe
(e), and doubtless serve to convey to it the
vibrations which affect the body generally.
The sinuosities in the intervals of these pro-
cesses seem to be the first rudiments of those
which in the higher classes are extended in the
form of canals and spiral chambers within the
substance of the dense nidus of the labyrinth.
The otolithe in the Sepia officinalis is of an ir-
regular flattened quadrangular figure, with two
of the angles produced so as somewhat to re-
semble the human incus: the surface next the
parietes of the sacculus is convex and smooth,
the opposite one concave and broken: it is
white and transparent. (In fig.235, the oto-
lithe is seen as exposed in the sacculus on the
right side.)

In the Octopus vulgaris the vestibules are
nearly spherical, and their parietes are smooth ;
the otolithes are of an hemispherical figure at-
tached to the dorsal part of the membranous sac,
of a white colour on the adherent’surface, and
yellow on the opposite side: the rest of the
sacculus is filled with a transparent gelatinous
fluid. The auditory nerve divides into three
branches, which spread over the sacculus, and
convey to the sensorium the vibrations which
affect the-otolithe and its sac.

Cuttle-fish.

CEPHALOPODA.

Organ of Hearing,

In the Eledone cirrosa the otolithe is shaped =
like the shell of a limpet, with the apex led
and curved backwards; of a pink colour on the
sides, but of a white semitransparent texture
internally. oe

The otolithes in all the Dibranchiates effer-
vesce with acids, like other substances com- _
— of carbonate of lime; and in the Poulp,

ledone, and all the Decapods, except the
Cuttle-fish, they are the only earthy substances
which enter into the organization of these
animals.

Organ of Smell——The sense of smell has
been attributed to the Cephalopods by all natu-
ralists who have written on their habits ; from
Aristotle, — who mentions the strong-scented
herbs which the Greek fishermen attached in
his day to their baits, in order to prevent their
being destroyed by the Mollia,—down to
Cuvier, who expressly asserts that they are at-
tracted by the odour of different substances.
But no organ expressly appropriated to the ex-
ercise of the olfactory sense has been deter-
mined in the Dibranchiate Cephalopods.

In dissecting the Nautilus Pompilius, our
attention was directed to a series of soft mem-
branous lamine (A, fig. 231) compactly arran-
ged in a longitudinal direction, and forming a
circular body very closely resembling the lami-
nated olfactory organ in Fish. The position of
these laminz, as well as their form and arrange~
ment, supported the belief that they exercised
the functions of an olfactory organ; being
situated just before the entrance of the mouth,
between the internal labial processes : nerves
were also traced to them from the inferior labial
ganglions. From analogy we are inclined to
suppose that the external lips in the Dibranchi-
ate order may be the seat of the olfactory sense.

Organ of Taste-—From the elaborate strue-
ture which the tongue displays in both orders
of Cephalopods, there can be no doubt but that
these destructive creatures fully relish the prey
that they devour, and, in correspondence to their
particular tastes, are led to select those species
the limitation of whose increase is assigned to —
their charge.

The anterior soft papillose lobes of the
tongue of the Nautilus are shewn in the sub-
joined figure (fig. 236), in which they are

mF

4
le ee

il i ae

denoted by the letter c; e indicates the midd
spiny plate, f the posterior coarser papillos
surface, and g the faucial folds. The nerve:
of this part are derived from the brain itself, o
supra-cesophageal mass. fi

CEPHALOPODA. 555

Organ of Towch—With respect to the sense
of touch, the exposed part of the integument
of the Nautilus presents numerous oy carte
eminences ; and several of the naked Cepha-
lopods are remarkable for the irregular surface
of the skin, which seems designed to increase
its natural sensibility. Thus, in the Cranchia
scabra, flattened processes terminating in nu-
merous pointed denticulations, project from
the surface of the mantle; in the Sepia papil-
lata the integument is beset with branched
papille ; in Sepia mammillata with more sim-
ple obtuse eminences; in Sepia tuberculata,
with tubercles; in Octopus aculeatus, with
pointed tubercles, &c. That these projections
serve to warn the creature of the nature of the
surfaces which come in contact with its
body is highly probable; and itis not at all
uncommon to find in those species, which have
smooth skins over the body generally, that
there are tubercles in the immediate neigh-
bourhood of the eyes, as in the Octopus
vulgaris, Octopus Lichtenaultii, Octopus Wes-
terniensis, &e.

In the Nautilus, the more exposed pedun-
culate eyes are expressly provided with re-
tractile sensitive tentacles on each side, as has
been already mentioned.

With respect to the organs destined for the
active exercise of touch or exploration, we
must suppose that the numerous tentacles with
which the Nautilus is so remarkably provided,
from the softness of their texture, their an-
nulated surface, and liberal supply of nerves,
serve in this capacity as well as instruments of
prehension and locomotion. The less nu-

merous but more highly developed arms of

Fig. 237.

Male Organs, Poulp,

the Dibranchiates doubtless exercise the same
faculty, especially at their attenuated flexile
extremities.

The internal fringed circular lip surrounding
the mandibles, in both orders of Cephalopods,
presents another example of the dermal co-
vering so disposed as to be the seat of delicate
sensation.

Generative System.—tThe individuals of
the present class are, as before stated, of distinct
sexes, which in the Dibranchiate order are re-
cognizable by diversity of size, external form,
colour and shape of the internal rudimental
shell. In the common Calamary, for example,
the gladius of the male is one-fourth shorter,
but broader than that of the female.

As only the female organs are known in the
Tetrabranchiate order, we are limited in the
description of the male parts, to those which
exist in the Dibranchiate Cephalopods; but
from the close resemblance subsisting in the
two orders in the form of the organs of the
female sex, little difference can be expected to
exist in the structure of the male apparatus.

In the Poulp the male organs consist of a
testicle, a vas deferens, a kind of vesicula
seminalis, a gland compared by Cuvier to the
prostate, the sac containing the moveable fila-
ments which Needham’s description rendered
so celebrated, and lastly the penis.

The testicle is situated at the bottom of the
visceral sac, and is composed of a membra-
nous pouch (a, fig. 237), to one part of the
inner surface of which are attached a number
of branched elongated glandular filaments (6),
which swell at the breeding season, and dis-
charge an opake white fecundating fluid into
the sac. From this cavity the fuid escapes
by the orifice (c), and passes into the vas de-
ferens (d). This is a narrow tube, indefinitely
convoluted upon itself; it opens into another
larger canal (e), the interior of which is di-
vided by ridges and incomplete septa; its
texture seems to be muscular, so that it pro-
bably serves by its contractions to eject the
fluid carried into it by the vas deferens. From
the vesicula seminalis the semen next traverses
the extremity of an oblong gland (f), which
is of a compact granular structure, and, like the
prostatic or Cowperian glands, contributes some
necessary secretion to the fecundating fluid.

Next follows the muscular pouch (g) con-
taining the filaments or animalcules of Need-
ham (fh). When first exposed, they present
the appearance of white filaments, from six to
eight lines in length, packed closely and regu-
larly in parallel order, in three or four rows
one above another, from the fundus to the
aperture of the pouch; and they are kept in
that position by a spiral fold of the membrane
of the pouch, without, however, having the
slightest adhesion to that part. For a long
time after being removed from their position
they continue to exhibit, when moistened,
motions of inflection in different directions.
A short and narrow canal (7) leads from the
pouch to the root of the penis (/), which is
a short pyramidal body, hollow within, and
terminating by a small anterior aperture;

202

556

In the Sepiola the part corresponding to
that called the prostate by Cuvier exists, but
is relatively smaller, and the duct by which it
communicates with and is appended to the
vas deferens is relatively longer; the sac of the
filaments is relatively larger, exceeding doubly
the dimensions of the testis; the penis is much
shorter.

In the Onychoteuthis the penis is merely
grooved, as in the Pectinibranchiate Mollusks,
not perforated, and such may be expected to
be its structure in the Pearly Nautilus.

With respect to the act of impregnation in
the Cephalopods, Aristotle gives two accounts.
In the fifth book of the Historia Animalium
it is stated that the Octopus, Sepia, and Cala-
mary, all copulate in the same manner; the
male and female having their heads turned to-
wards one another, and their cephalic arms
being so co-adapted as to adhere by the mutual
apposition of the suckers. In this act the
Poulps are described as seeking the bottom, while
the Cuttles and Calamaries are stated to swim
freely in the water, the individual of one sex
moving forwards, the other backwards. Aris-
totle also observes that the ova are expelled by
the funnel, which the Greeks called physetera
(Quonrnex), and some, he adds, assert that the
coitus takes place through that part.

From the position of the oviduct at the base
of the funnel, and the inclination of the penis
to the same part, from the left side, the latter
supposition derives some probability, espe-
cially with respect to the Sepia and Sepioteu-
this, in which the penis is of large size, although
true intromission is physically impossible in
these, as in all other Cephalopods. There
may, however, be an imperfect connexion,
analogous to that of the Frog, Toad, &c. and
it is worthy of remark that the differences in the
situation where the coitus is said to take place,
in Aristotle’s remarkable account, corresponds
with the modifications of the locomotive powers
in the three genera treated of; it is only, for
example, in the Sepia and Loligo that the indi-
viduals are provided with posterior fins for
swimming forwards.

In the twelfth chapter of the sixth book of
the Historia Animalium, where the generation
of Fishes is treated of, the Stagyrite ob-
serves —‘ When they (fishes) bring forth,
the male following the female sprinkles the
ova with his semen :—the same thing happens
inthe Malakia; forin the genus Sepia, where the
female deposits the ova, the male follows and
impregnates them : this possibly happens in like
manner to other Malakia, but, hitherto, it has
been observed in the Sepie alone.’ It reflects,
perhaps, little credit on modern Naturalists,
that the knowledge of this part of the eco-
nomy of the Cephalopods should remain in the
same unsatisfactory and conjectural state as it
was two thousand years ago.

The female organs exhibit four principal
types of structure in the Cephalopods.

The ovary is single in all.

In the Nautilus there is one oviduct, and
one oer glandular appendage.

In the Sepia and many others, there is also

CEPHALOPODA.

Female Organs of the Nautilus.

one oviduct, but there are two separated ni-
damental glandular laminated organs which
open near its extremity.

In the Loligo sagittata there are two distinct
oviducts, and two separate nidamental glands.

In the Octopoda there are two distinct ovi-
ducts, each of which, as in the Ray and Shark,
passes through a glandular organ in its course
towards the base of the funnel, but there are
no detached glands.

In the Nautilus the ovary (a, fig. 238) is
situated, as in the higher Cephalopods, at the
posterior part of the visceral sac, in a distinct
compartment of the peritoneum; and the
gizzard, which here descends lower down than
in the Dibranchiata, is lodged by its side.
The ovary is of an oblong compressed form,
and in the specimen dissected, measured one
inch and a half in length and one inch in
breadth. It consists of a simple undivided
hollow sac, with thick and apparently glan-
dular parietes, rugose on the inner surface,
and having an anterior aperture (6) with puck-
ered margins, directed forwards.

The ovisacs (c, c) are numerous, of an oval
form, and attached by one extremity, in a
linear series, along the internal surface of the
ovarian sac on the dorsal aspect. In the
specimen here described they were collapsed,
and had evidently recently discharged their
ova; the rent orifices by which these had
escaped were still patent and conspicuous. The
tunics of the ovisacs, as in the Dibranchiata,
were glandular, but the internal plice did not
present the reticulate disposition characteristic
of the corresponding parts in the Sepia, &c. ©
The exterior thin membrane (d) of the ovary —
is continued forwards to form the oviduct:
the thick glandular tunics of this canal com-—
mence by a distinct aperture (€), just above
the outlet of the ovary, and continue incr
in thickness to the extremity of the oviduct,
where the glandular membrane is di
in numerous deep and close-set folds: the

OS a re -

‘
g-

7}

~Decapod

4
. °
;

CEPHALOPODA. 557

length of the glandular part of the oviduct is
one inch; its termination is at the base of the
funnel close to the anus, and immediately
behind an accessory glandular apparatus.

This body is analogous to the laminated
ovarian gland of the Pectinibranchiate Tes-
tacea, and, as in them, forms no part of the
oviduct; but in the Nautilus it is extended in
the transverse direction, and composed of two
lateral convex symmetrical masses, resem-
bling the corresponding separate symmetrical
glands in the c, aenaet but which are here
united by a third middle transverse series
of lamine. All the lamine are deep, pec-
tinated, and close-set, and are supplied by
a large artery. The lateral groups form
conspicuous projections on the external sur-
face of the ventral aspect of the Nautilus,
and are covered internally by a layer of thin
tough membrane; the middle lamine are
exposed.

e female organs of the Dibranchiate Ce-
phalopods present different structures, as be-
fore observed, in the Decapodous and Octo-
podous tribes. In the former the oviduct or
oviducts have laminated glandular termina-
tions, near to which are placed two detached
nidamental glands: in the latter there are al-
ways two distinct oviducts which pass through
laminated glands, but there are no detached
superadded glandular organs.

e Sepia, among the Decapodous Cephalo-
pods, manifests in its generative, as in its
prehensory and testaceous organs, a near affinity
to the Tetrabranchiate order, while the form
of the female apparatus in the Octopods more
closely corresponds, on the other hand, with
the same parts in the Oviparous Cartilaginous
Fishes. Ihe ovarium in both tribes is a single
organ, situated at the bottom of the pallial sac,
and consisting of a capsule and ovisacs di-
versely attached to its internal surface.

The ovisacs are proportionally larger in the
s than in the Octopods. In the
Cuttle-fish they are extremely numerous, and
are appended by long and slender pedicles to
a longitudinal fold of membrane extending
into the ovarian cavity, from the dorsal aspect
of the sac. The plice of the internal glan-
dular surface of the ovisacs or calyces are
disposed in a reticulate manner, forming cor-
responding light-coloured opake lines on the
external surface,which, being contrasted against
the dark-brown tint of the contained ovum
shining through the transparent areolar space,
occasions the beautiful and characteristic ex-
terior reticulate markings of the undischarged
ovisacs.

In the Genus Rossia, from which the sub-

| _ joined illustration of the Decapodous type

of the female organs is taken (fig. 239), the

a Ovisacs have the same structure and mode

of attachment as in Sepia, but they are rela-
tively of double the size and fewer in num-
In the specimen which we dissected,
we found the greater part of the ovisacs con-
taining the ovum in various stages of deve-
lopment, as at a,a. One was in the act of
shedding the ovum, as at 6, f; others were

Female generative Organs, Rossia palpebrosa.
( Natural size. )

discharged, collapsed, and shrivelled, and in
progress of absorption, as atc, c. The pa-
rietes of the ovarium consist of a thin and
almost transparent membrane, which is con-
tinued forwards to form the oviduct (d, d).
This canal commences in the Cuttle-fish by a
round aperture, about a third of an inch in
diameter, immediately beyond which it dilates,
and continues forwards of the same thin and
membranous structure to within an inch of its
extremity, where, as in the Nautilus, its pa-
rietes are suddenly thickened by the develop-
ment of a number of broad, ciose-set, glan-
dular lamine. The chief difference between
the Sepia and the Nautilus obtains in the greater
extent of the membranous part* of the oviduct
in the former.

In the Rossia the oviduct (d) differs only in
greater relative width: the terminal gland (e)
is composed of two lateral semioval groups
of transverse glandular lamellz, each group
being divided by a middle longitudinal groove ;
the oviduct was contracted immediately before
opening into the interspace of the glands, and
a deep but narrow groove, which is probably
dilated during the passage of the ova, was
continued between the two groups of lamellz
to the termination of the oviduct. This was
situated towards the left side and behind the
orifices of the nidamental glands.

The female organs of the Sepiola present the

* In the original description of the Nautilus, this
membranous part of the oviduct was regarded,
from its brief extent, and the sudden commence-
ment of the glandular tunic, as a connecting process
of the peritoneum ; it was accurately represented,
however, in the figure, (pl. viii. fig. 9.)

558

same structure as in Sepia and Rossia, but the
single oviduct is relatively wider than in the latter
genus, the ova being of remarkably large size.
In the Calamary the ovary is more elongated,
and the ovisacsand ova are relatively smaller than
in any of the above genera. In the common
species ( Loligo vulgaris ) the oviduct is single,
but narrower, and more elongated than in the
Sepia, and, like the vas deferens in the male,
it is disposed in convolutions; its terminal
gland is relatively larger and longer; and the
detached nidamental glands are correspond-
ingly restricted to a smaller development.

In the great Sagittated Calamary, which is
not uncommon on our north-western shores,
we found in a large specimen taken before the
beginning of the breeding season, that the
oviducts commenced by separate apertures
about two inches apart from the anterior sur-
face of the great ovarian bag, and were imme-
diately disposed in sixteen short transverse
folds, beyond which they continued straight
to the terminal ovarian gland. The whole
length of each oviduct was two inches; the
convoluted portion occupying one inch ;
the straight and glandular parts each half
an inch. Monro, in his anatomy of this
species of Loligo, conjectured that the glan-
dular appendages of the biliary ducts, of
which he gave a figure, were the ova: of
the oviducts and nidamental glands he had
no knowledge. The latter parts are situated
external to the terminations of the oviducts;
they are of a narrow, elongated, flattened form,
about one inch and a half in length, with a
wide cavity for moulding the secretion of the
two lateral series of glandular Jamine.

The ova which are contained in the mem-
branous part. of the oviduct of the Sepia,
consist of a deep yellow vitellus, inclosed,
first, in a very delicate vitelline membrane,
and, externally, in a thin, smooth, shining,
easily lacerable, cortical tunic, or chorion.
We have generally found them in great num-
bers, squeezed together in a mass, so that few
retained their true form.

The external tunic of the ova in Rossia is
stronger than in Sepia, and the form of the
ovum, which is elliptical, is consequently bet-
ter preserved: the oviduct, in the specimen
dissected by us, contained several ova detached
from one another, in progress of exclusion,
as represented in the figure at f,f. The ova
in Sepiola, as in the two preceding genera,
are devoid of any external reticulate markings,
which belong only to the ovisac or formative
calyx.

The delicate ova are defended by additional
layers of a horny substance deposited on their
external surface by the terminal gland, which
may be compared to the shell-secreting segment
of the oviduct in the Fowl. When the ova
quit the oviduct, they are connected together
by, and probably receive a further covering
from, the secretion of the two large super-
added glandular bodies (g, 8, fis. 239), the wide
ducts of which converge and open close to the
termination of the oviduct.

These bodies, in the Cuttle-fish, Sepiola,

CEPHALOPODA.

and Rossia, are of a pyriform shape with the
apices, converging and turned forwards; of large
size, especially at the reproductive season, situ-
ated on the ventral aspect of the abdomen,
but not attached, as in the Nautilus and in-
ferior Mollusks, to the mantle. They are each
composed of a double series of transverse,
parallel, close-set semi-oval lamine, the ;
straight margins of which are free and turned J
towards each other along the middle line of
the gland. When the gland is laid open, an
impacted layer of soft adhesive secreted sub-
stance is found occupying the interspace of
the two series of laminz; in which, in Rossia,
it is evidently moulded into a filamentary form,
whence it escapes by the anterior orifice above
mentioned. (See h, h, fig. 239.)

The lamine are attached by their convex
margins to the capsule of the gland, which is
thin, and probably contractile; it is com-
pletely closed at every part save the anterior
outlet, forming a shut sac posteriorly, and
having no communication with the oviduct or
oviducts, for which these glands have some-
times been mistaken.*

In the Cuttle-fish the extremities of the
ovarian glands rest upon a soft parenchymatous
body of a bright orange colour: the correspond-
ing part is rose-red in the Sepiola, and of a
bright colour in all the congeneric species. In
the Sepia this body is trilobate, consisting of two
lateral slightly compressed conical portions,
whose obtuse apices are directed forwards, and a
smaller middle portion connecting the lateral
ones at their posterior and internal angles.
The dorsal surface of the lateral lobes is flat-
tened, the opposite side excavated to receive
the superincumbent extremities of the ovarian
glands. ‘To these the substance in question is
closely attached by a tough connecting mem-
brane, but has no correspondency of structure
nor any excretory outlet. Its texture is dense
and granular, with minute cells, the largest of
which are in the centre of the body, and are
filled with a yellowish brown caseous substance.
In Sepiola the corresponding body is single,
and is similarly attached to the anterior extre-
mities of the two nidamental glands. In the

* In the description of the anatomy of the Loligop-
sis by Dr. Grant, contained in the first volume of the
Zoological Transactions, it is stated that “ the
usual large glands of the oviducts appear to be
wanting,” p.26; whence we are led to conclude
that the oviducts are double in that genus as in the
Octopods. Rathke, however, describes the oviduct
as being single, and states that it is continued
downwards to terminate at an aperture situated on
the ventral surface of the hinder extremity of the
body. This is so singular a deviation from the
Cephalopodons type of structure, and makes so
important a step towards the Vertebrate Organiza-
tion, that we have selected the figure ( (9; 273)
in which the learned author above quoted illustrates
this part of his observations on Loligopsis, where —
14 represents the ovary, 15 the oviduct, and 16 its —
posterior terminal apertiige. Further dissection ¢
this remarkable genus is, however, evidently re-
quired, in order to reconcile the discrepancies |
the accounts of the anatomy of these animals whi
have hitherto been publis ed, both as to the ge-
nerative system and in reference to other important
structures. ay

et in

:
:
M

CEPHALOPODA. 559°

Loligines and in Rossia it is double; each
portion (i, 2, fig. 239) in the latter genus is at-
tached by cellular tissue to the anterior part of its
corresponding nidamental gland, and 1s excava-
ted by a deep groove close to the aperture of the
gland : from this structure and their position it
would appear that they assisted in moulding
the nidamentum, and, perhaps, in applying it
to the ova. Considering the texture of these
singular bodies, their ordinarily bright colour,
and their relative position to the generative
apparatus, we believe ourselves justified in
regarding them as the analogues of the glan-
dul succenturiate or ‘ supra-renal bodies’ of
the Vertebrate animals.

In the Octopodous Dibranchiates the ovary is
a spherical sac with thick parietes (1, fig. 226).
The ovisacs (2) are racemose or connected in
bunches, and attached in the Poulp to a single
point of the ovarian capsule, but in the Eledone
to about twenty ayn stalks suspended from
the upper part of the ovary. The ova, when
detached from the ovisacs, escape by a single §
large aperture (3), leading from the anterior part
of the sac into a very short single passage,
which then divides to form the two oviducts.
These tubes, in the unexcited state of the ge-
nerative system, are membranous, straight, and 3
of an uniform narrow diameter, except where &
they perforate a glandular laminated enlarge- =
ment (4), situated about one-third from their Z
commencement; but, towards the period of ovi- ©
position, the parietes of the oviducts increase
in thickness and extent, forming longitudinal «2
folds internally.

The laminated glands doubtless serve to pro-
vide an exterior covering to the ova, and con- &
nect them together, thus performing the func-
tion of the accessory external glands in the Z
preceding tribe. The oviducts ascend behind
the lateral hearts and venous cavities, aud open 77
on each side of the mediastinal septum of the 7
branchial cavity opposite the middle of the /7
gills (5, 5). ,

A glandular body surrounds each oviduct in 7/Y,
Eledone, but is situated nearer the lower end 7
of the tubes, and is of a darker colour than in
Octopus. |

In Argonauta the oviducts are continued by
a short common passage from the ovary, and
form several convolutions before they ascend to
their termination, which is the same as in Oc-
topus; they differ, however, from both the
preceding genera in having no glandular lami-
nated bodies developed upon them: the minute
ova of this genus are, therefore, connected ’ §- 243.
together by the secretion of the lining mem- PHN
brane of the long and tortuous oviducts.

__ Incorrespondence with the striking differences
which the female organs present in the Cephalo-
pou. class, it is found that almost every genus

its own peculiar form and arrangement of
ova after their exclusion. Of these, therefore,
we proceed to give a short description of the
principal varieties.

The ova of the Argonaut are invariably found . Me
occupying a greater or less proportion of the Ova of the Calamary, Loligo Vulgaris.*
bottom of the shell; they are of an oval form, te
about half a line in length before the develop- * From Férussac, Monographie des Céphalopodes.

560

ment of the embryo has commenced, and are
connected together in clusters by long filamen-
tary processes.

In the figure subjoined, (fig. 240), A repre-
sents the ova of the natural size, B a group of
ova at an early stage of embryonic develop-
ment, magnified, C a single ovum, still more
highly magnified, showing the embryo a, the
rudimental feet b, and what would be regarded
as the vitellus c, in the ovum of any of the
naked Cephalopods, but which the continuator
of Poli states to be the germ of the shell.
With respect to the Poulp ( Octopus) Aristotle
states that the animals of this genus copulate
in winter and bring forth in spring: that the
female oviposits in a shell or some secure
cavity; that the ova adhere in clusters, like the
tendrils of the wild vine or the fruit of the
white poplar, to the internal parietes of the
cavity; that the young Poulps are hatched on
the fifteenth day, and are then seen creeping
about in prodigious numbers.*

The ova of the Calamary (fig. 241) are in-
closed in cylindrical gelatinous sheaths, mea-
suring from three to four inches in length, and
about a quarter of an inch in diameter at the
thickest part, narrowing to an obtuse point at
one end, and attached at the opposite extremity
by a filamentary process, varying from half an
inch to an inch in length, to some foreign body,
as floating wood, &c.; each sheath or nidamen-
tum contains from thirty to forty ova, of a
spherical figure, about a line and a half in
diameter when newly excluded. As the num-
ber of cylinders attached to one body some-
times exceed two hundred, the prolific nature
of the specits may be easily conceived.

Fig. 242 shows the first appearance of the
head and eyes a, at the stage prior to the
development of the arms and funnel ; 6 is the

Fig. 244.

Ova of the Cuttle-fish, Sepia Officinalis.
* Hist, Animal, lib. v. cap. 16.

CEPHALOPODA.

elongated body, c the yolk-bag. Fig. 243
is another ovum ata more advanced stage of
development: the pigmentum is now deposited
both in the rete mucosum and in the eye; the
arms are just beginning to shoot from the ante-
rior circumference of the head; and the little
funnel may be observed rising above the ventral
margin of the mantle. :

The ova of the Sepioteuthis are also spherical
and enveloped in cylindrical sheaths, but these
are much shorter than in the Loligo, and contain
much fewer ova, making an approach in this
respect, as in the general organization, to the
Sepiz, in which each ovum has its own nida-
mentum.

The eggs of the Cuttle-fish (fig. 244) are of
an oval form, attenuated at the extremities,
envelo in a flexible horny covering, of a —
blackish colour, which is prolonged into a pe-
dicle at one extremity, and twisted round some
foreign body. The length of ovum from the
point of its attachment is generally an inch,
and as a number of these ova are always found
attached close together, and sometimes to one
another, they resemble in this state a bunch
of grapes, as the name ‘ sea-grapes,’ com-
monly given to them by the fishermen, implies.

In the development of the Cephalopod the
most interesting circumstance, and one which
had not escaped the notice of Aristotte,* is the
point of attachment of the yolk-bag (¢, fig. 245),
which is suspended from the
head of the embryo, its pe-
dicle being surrounded by
the cephalic arms, and passing
down anterior to the mouth
to communicate with the
pharynx. The yolk is a trans-

arent gelatinous fluid of a
spherical form.

In the embryo of the Cuttle-fish all the
organs, the exercise of which is essential to its
future welfare, are adequately developed before
its exclusion. The gills are very distinct, and
the respiratory actions are vigorously performed
by the alternate dilatation and contraction of
the mantle and a corresponding elevation and
falling of the funnel (d), by which the little
streams are expired. Tlie ink-bag has already
pac eneey a store of secretion sufficient to

lacken a considerable extent of water, and
baffle any enemy which may be ready to remove
the little Cephalopod from the world into which
it is about to enter. The pigment of the rete
mucosum is developed in several large spots,
as in the Calamary (fig. 243).

Five concentric layers of the dorsal shell at
least are deposited ; these are, however, horny,
white, and transparent, except at the narrow
and thick end; and the ionermost layers are
marked with irregular opake spots. The lateral —
fins are broad, and the ventral arms are furnished
with a fin-like expansion, so that the young
animal is enabled to execute movements either —
retrograde or progressive ; and the eyes are well

Pig. 245.

*Tioormipune on yryvopdyn ontia Tots wole Kata T re

/ ~ ey
mpoxBiov. ‘ Adheret ovo Sepia nascens parte Su
priore.” De Generatione Animalium, lib. ili, ¢. 8. ~

CEPHALOPODA.

developed and proportionally large to direct its
evolutions.

BIBLIOGRAPHY (ANATOMICAL). Aristotle,
Historia de Animalibus, cur. Schneider, Lipsiz,
lib. iv. cap. 1, 2, & 4; lib. v. cap. 6 & 18; lib. vi.
cap. 13; lib. viii. cap. 2 & 30; lib. ix. cap. 36.
De Partibus Animalium, lib. iv. cap. 9.

In these several parts of his extraordinary work
Aristotle indicates nine different species of Cepha-
lopods, with so much precision and so happy a se-
lection of their distinctive characters, that modern
naturalists have been enabled to identify almost
all the species which were studied by the Stagyrite
two thousand years ayo.

Of these we may first mention the Nautilus
which adheres to its shell, and which we conceive
may have been the Nautilus Pompilius ; second, the
Nautilus which does not adhere to its shell, universally
allowed to be the Argonauta or Paper Nautilus of
the moderns; third, the Cuttle-fish (Sepia offici-
nalis ); fourth and fifth, the great and small Cala-
maries (Loligo vulgaris and Loligo media); sixth
and seventh, the great and small Poulps; the
former is regarded by Belon and Rondeletius to
have been the Sepia octopodia of Linneus ; but the
small species, which Aristotle states to have been
variegated,* has not yet been satisfactorily deter-
mined ; eighth, the Bolitena, a genus of Octopods
which Aristotle characterized by its peculiar odour ;
this is the Eledona moschata of Leach ; ninth, the
Eledone, characterized by the single series of suck-
ers, and to which the £ledona cirrosa of Leach
corresponds.

Respecting the living habits of the Cephalopods,
Aristotle is more rich in details then any other
zoological author, and Cuvier has justly observed
that his knowledge of this class, both zoological
and anatomical, is truly astonishing.

Swammerdam, Biblia Nature, seu Historia In-
sectorum, 1737, 1738, or ‘ The Book of Nature,’ &c.
translated by Thomas Flloyd and J. Hill, London,
1758, fol. Towards the end of this work there
is a letter from Swammerdam to Redi, in which
are given the first anatomical details, in addition
to those of Aristotle, which appeared after the
revival of literature: the external parts and struc-
ture of the tongue are carefully described; the
viscera and the nerves with less exactness; and
the organs of circulation erroneously.

Needhum, An account of some new microsco-
pical discoveries, 8vo. London, 1745. At page 22
we find the first description of the armed suckers
of the Calamaries: Chapter V. contains the curious
account of the seminal filaments of the male
Cephalopods. ;

Baker, An account of the Sea-Polypus; Philo-
sophical Transactions, vol.1. 1758. Bohadsch, Dis-
sertatio de veris Sepiarum ovis, 4to. Prage, 1752,
Josephus Theophilus Koelreuter, Polypi marini,
Russis Karakatiza recentioribus Grecis oxrumovs
dicti, descriptio. Nov. Comm. Acad. Petropol.
tom. vii. p. 321-343, 1759. Lamorier, Anatomie
de la Seche, et principalement des organes avec
lesquels elle lance sa liqueur noire; Mém. de la
Soc. de Montpellier, tom. i. p. 293-300, 4to. 1766.

John Hunter on the organ of hearing in fish ; Phi-
losophical Transactions, 1782. In this paper we
find the first announcement of the existence of an
organ of hearing in the class Cephalopoda. Nu-
merous preparations in his Collection attest Mr.
Hunter’s extensive knowledge of the rich and
singular organization of the Cephalopods: for his
accurate description and beautiful figures of the
circulating and respiratory organs, the reader is
referred to the second volume of the Descriptive
and Illustrated Catalogue to the Hunterian Collec-
tion, 4to. and to the first volume of the same work,
for the descriptions of his preparations of the hard
parts and digestive organs of the Cephalopods :

* "Ere DE adrAos peinpol, moinidor, of ode EoOiovres.

561

among the latter Mr. Hunter had placed the ‘ Pan-
creas of the Cuttle-fish.’”

Monro (Secundus). The structure and physiology
of fishes explained, &c. fol. Edinburgh, 1785. This
work contains (p. 62) the anatomy of the Sagittated
Calamary ( Loligo sagittata, which the author terms
the Sepia loligo), and from its organization he
ably deduces its true place in the natural system,
observing that ‘ by most authors it has been ranked
among Fishes ; by Linneus it has been placed among
the worms: but perhaps it may most justly be con-
sidered as a link connecting the two classes of
animals.” Monro confirms the discovery of Hunter
of the acoustic organ, and figures the otolithe of
the Calamary. He first published the true descrip-
tion of the three hearts, and rectified the errors of
Swammerdam on this part of the anatomy of the
class: he notices the absence of the vene porte,
and some of the peculiarities in the structure of
the eye; but his description of the generative
system, and his notice respecting some other particu-
lars, as the urinary and gall-bladder, are erroneous.

Scarpa, Anatomice disquisitiones de auditu et
olfactu, fol. 1789. The anatomical descriptions
relative to the Cephalopods are limited chiefly to
the organ of hearing, and the course of the nerves ;
the account of the latter is incomplete and in part
erroneous.

Tilesius, in the Beitrage fiir die Zergliederungs-
kuust von H. F, Isenflamm, B. 1. Heft. 2.

G. Cuvier, Lecons d’ Anat. Comparée, 1799 to 1805.
These five volumes contain the results of numerous
researches on the anatomy of the Cephalopoda, all
characterized by the author’s usual depth and
accuracy. They are collected together with addi-
tional details and beautiful figures in the celebrated
‘ Mémoire sur les Céphalopodes et leur Anatomie,’

ublished in 1817, in the Mémoires sur les Mol-
usques, 4to. The type of organization illustrated
by these researches is considered in the author’s
subsequent work (the Régne Animal), as charac-
teristic of the class Cephalopoda; but the chief pe-
culiarities are found only in the Dibranchiate Order.

De Blainville, De Vorganization des animaux, ou
principes d’anatomie comparée, tom. i. 8vo. 1822.
Contains observations on the skin and organs of
sense of the Cephalopods. Ejusdem, Manuel de la
Malacologie, 8vo. 1825.

Home (Sir Everard), Lectures on Comparative
Anatomy, 4to. 1814-1828. On the distinguishing
characters between the ova of the Sepia and those
of the Vermes testacea. Philos. Trans. cvii.

Leach, (W.E. M.D.) On the genus Ocythoé.
Phil. Trans. cvii. Appendix to Tuckey’s Voyage
tothe Congo. Zoological Miscellany, vol. iii.

Rathke, Ueber Perothis, &c. (on the anatomy of
the Loligopsis ); Mém. de l’Acad. Imp. de Peters-
bourg, tom. ii. parts 1 & 2, p. 169, 1833.

Roget (P.M. M.D.) kridgewater Treatise, on
Animal and Vegetable Physiology, 8vo. 1834,

Robert Grant, M.D. &c. Description of a new
species of Octopus ( Oct. ventricosus, Grant); Edinb.
Philos. Journal, vol. xvi. p. 309. On the structure
and characters of Loligopsis, &c. and on the anatom y
of the Sepiola vulgaris, Leach. ‘Transactions of
the Zoological Society, part i. 4to. 1833. Lectures,
Lancet, 1833-4. Outlines of comparative anatomy,
parts 1 & 2, 8vo. 1835.

Delle Chiaje, Memorie sulla storia degli animali
senza vertebre del regno di Napoli, 1823-1829,
4 vol. 4to.

San Giovanni, Giornale Encicl. di Napoli, 1824 ;
Annales des Sciences Naturelles, tom. xvi. p- 305.
(His memoirs on the structure and properties of the
colorific stratum of the skin of Cephalopoda are
contained in the above works. )

J. Coldstream, M.D. see Edinb. New Philosophi-
cal Journal, July, 1830, p. 240; and, On the deve-
lopment of the ova of Sepia officinalis, Proceedings
of the Zoological Society, part i. 1833, p. 86.

Mayer, Analekten fur Vergleichenden Anatomie,
Ato. 1835,

562

Férussac, M. le Baron, & A. D’Orbigny, Mono-
phie des ga tig Acétabuliféres, folio,
aris, 1835. This splendid work is published in
numbers, of which eleven have appeared. As yet
the letter~press extends only to the general intro-
duction. :
<eesg (W. J.) Observations on the animals
hitherto found in the shells of the genus Argonauta,
Zoological Journal, vol. iv. p. 57. ;
Richard Owen, Memoir on the Pearly Nautilus
( Nautilus Pompilius, Linn.) 4to. 8 plates, 1832.
This work contains, besides the description of the
structure which characterizes the lower or Tetra-
branchiate order of the class, some additional par-
ticulars on the structure of the infundibulum, and
of the brain, and on the function of the superadded
branchial hearts, in the Dibranchiate order of
Cephalopods. Descriptive and illustrated Catalogue
of the Physiological Series in the Museum of the
Royal College of Surgeons, Ato. vol. iiie contains
an account of the organs of sight and hearing in
the Cephalopods, 1835. Description of a new genus
of Cephalopoda (Rossia). Appendix to Sir John
Ross’s Voyage, 1835. Descriptions of some new
species ; and anatomical characters of the Orders,
Families, and Genera of the class Cephalopoda,
Proceedings of the Zoological Society, March, 1836.
( Richard Owen.)

CERUMEN, (Germ. Ohrenschmalz.)—This
secretion, formed by the glands of the ex-
ternal ear, has been examined by Fourcroy
and Vauquelin, and more in detail by Ber-
zelius.* According to Vauquelin it consists
of 0°625 of a brown butyraceous oil, soluble
in alcohol, and 0°375 of an albuminous sub-
stance, containing a peculiar bitter extrac-
tive matter. Berzelius observes, that, when
first secreted, cerumen appears as a yellow
milky fluid, which gradually acquires a brown-
ish colour and viscid consistency. Digested
in ether it imparts to it fatty matter, which re-
mains when the ethereal solution is distilled off
water; it has a soft consistence, is nearly co-
lourless, and contains stearin and elain sepa-
rable by alcohol; it is easily saponified, and
the soap which it forms has a rank unpleasant
smell and taste; and when decomposed by mu-
riatic acid, the fatty acids separate in the form
of a white powder, which rises with difficulty
to the surface, and fuses at about 105°. The
portion which remains after the action of ether
imparts a yellow colour to alcohol, and on its
evaporation there remains a yellew-brown ex-
tractive matter, soluble in water, and leaving
after the evaporation of its aqueous solution a
yellow, transparent, and shining varnish, which
is viscid and inodorous, but intensely bitter;
when burned, it exhales a strong animal odour,
and leaves an ash of carbonate of potash and
carbonate of lime, without any trace of a chlo-
ride. It is completely precipitated from its
aqueous solution by neutral acetate of lead.
That part of cerumen which is not soluble in
alcohol yields to water a small proportion of
pale yellow matter, which, when obtained by
evaporation, has a piquante taste; it is not
precipitable by salts of lead, corrosive subli-
mate, or infusion of galls, and contains no
traces of phosphoric or chlorine salts. The
residue of the cerumen, insoluble in water and

*®* Lehrbuch der Thierchemic.

CERUMEN—CETACEA.

alcohol, gelatinises in acetie acid, but is only —
partially dissolved by it; that which is n
up appears to be albumen; and the undis-
solved portion is brown, viscid, and
rent; digested in dilute caustic alkali it imparts
a yellow colour, but a small portion only is
dissolved ; and as nothing is thrown down by
supersaturation with acetic acid and ferrocy-
anate of potash, it is not albumen that is taken
up: the acid solution, however, is copiously
precipitated by infusion of galls, so that it
contains some peculiar principle. The residue
which resists the action of dilute alcali, when
boiled in concentrated solution of caustic pot-
ash, becomes brown, and smells like horns imi-
larly treated; a part of it seems to form a
compound with the alkali insoluble in the ley,
but soluble in water, in which respect it re-
sembles horn, but it differs from it in not
being precipitated from its solution by muriatic
acid, nor ferrocyanate of potash, and scarcely
by infusion of galls. It appears, therefore,
that cerumen is an emulsive combination of a
soft fat and albumen, together with a peculiar
substance, a yellow and very bitter matter
soluble in alcohol, and an extractive substance
soluble in water: its saline contents appear to
be lactate of lime and alkali, but it contains
no chlorides and no soluble phosphates. When
cerumen accumulates and hardens in the ear so
as to occasion deafness, it is easily softened by
filling the meatus with a mixture of olive oil
and oil of turpentine, by which its fatty matter

is dissolved.
(W. T. Brande.)
NERVES.

CERVICAL
NERVES.

See Spinan

CETACEA; Gr. xnrn, deadsvos, Aristotle ;
Eng. Whale tribe, Cetaceans; Fr. Cetacés ;
Germ. Wall-fische.

[An order of mammiferous animals, distin-
guished, as regards outward characters, by the
absence of hinder extremities, neck, hair, and
external ears; and by the presence of a large
horizontal caudal fin, and the fin-like form of
the anterior extremities, the bones of which are
shortened, flattened, and enveloped in a thick
unyielding smooth integument. With this con-
figuration the Cetaceans are fitted only for
aquatic life, and reside habitually in the waters
of the sea or of large rivers: their resemblance
to the true Fishes is so close that many natu-
ralists, since the revival of literature, and the
vulgar in all ages, have regarded them as mem-
bers of the same class. Aristotle, from his
anatomical knowledge, was aware of the essen-
tial differences between the Whalesand Fishes,
but it is not absolutely necessary to seek for
internal characters to establish the real distine-
tion which subsists between these different de-
nizens of the deep; the horizontal position of
the tail-fin at once distinguishes the cetacean
from the fish, in which that fin is vertical. This
difference relates to the different nature of
the respiration of the Whale, which is Mia! e
lungs, and consequently necessitates a frequent —
rising to the surface of the water to breathe the

ee =

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a
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F

et oe ae

:

CETACEA. 563

air, and a corresponding modification of the
chief organ of locomotion.

With the lungs are also associated the pre-
sence of warm blood, a double circulation, an
epiglottis, and a diaphragm, a true viviparous
generation, a nourishment of the young by a
mammary secretion, and in short all the essen-
tial parts of a mammiferous organization.

e order is subdivided as follows :

Tribe I. PHYTOPHAGA.

Char. Teeth of different kinds; molars
with flattened crowns, corresponding to
the vegetable nature of their food.
Mamma, two, pectoral. Lips provided
with stiff bristles. LErternal nostrils,
always two, situated at the extremity or
upper part of the rostrum, which is ob-
tuse.

Genus Mawnartus, Cuv.

Char. Incisors § (two superior, deciduous
in the foetus, not replaced). Molars 38,
grinding surface with tri-tuberculate
transverse ridges. Body with a few
scattered bristles. Anterior extremities
each provided with four nails. Tail-fin
oval.

Species 1. Manatus Americanus, Cuv.
Trichechus Manatus, Linn.: the Ma-
natee. Lamantin d’Amérique, Cuv.

2. Manatus Africanus, Lamantin du
Senegal, Cuv.

Genus Haticors, Cuv.

Char. Incisors 2. (In the young animal
the two superior permanent incisors are
preceded by two deciduous ones ; six
or eight deciduous incisors in the lower
jaw which have no permanent succes-
sors). Molars 33; (in the young ani-
mal $8); the grinding surface exhibits a
rim of enamel at the circumference and
a slightly excavated centre of ivory.
Body, with a few scattered bristles.
Upper lip with bristly mustaches. An-
terior extremities without nails. Tail-
fin very broad, crescentic.

Species 1. Halicore Indicus, Cuv. The
Indian Dugong, or, more properly,
Duyong.

2. Halicore Tabernaculi, Ruppel. Du-
gong of the Red Sea.

Genus Rytina, Illiger. Incisors none.
Molars 44, large, lamelliform, of a
fibrous structure, with the triturating
surface roughened by tortuous furrows.
Body, without hairs, but covered by a
rough and thick fibrous epidermis. An-
terior extremities terminated by an un-
guiform callosity. Cuudal-fin crescent-
shaped, each angle terminated by a
horny plate. :

Species. Rytina Stelleri, Le Stellére, Cuv.
This species inhabits the seas of Kamt-
schatka. It was discovered by the
Russian naturalist, Steller, after whom
it is named; and is described by him
with much zoological and anatomical
detail in the Nova Comment. Petrop.
t. li, p. 294, (1751,) under the name of
the Manati or Vacca marina.

Tribe Il. SOOPHAGA.

Char. Teeth of one kind or wanting, not
adapted for mastication. Mamme, two,
pudendal. External nostrils, double
or single, situated on the top of the
head.

A. with the head of moderate size.

Family DELPHINIDA. Teeth in both

jaws, all of simple structure, and gene-
rally conical form. No cecum.

Genus DeLeuinornyncnus. Rostrum
very long and narrow, continued not
abruptly from the forehead. Teeth very
small and numerous.

Ex. Delphinorhynchus micropterus. (Fred.
Cuvier, Cetacés, pl. viii. fig. 1.)

Genus De tpuinus. Rostrum narrow,
of moderate length, continued abruptly
from the forehead. Teeth conical,

.. _ Slightly recurved, numerous.

Ex. Delphinus Delphis, the common Dol-
phin; Delphinus Tursio, the Spouter
or small Bottle-nose Whale of Hunter.

For the other numerous species of this
genus consult F. Cuvier, Histoire des
Cetacés, p. 147 et seq.

Genus Inta. Rostrum, as in the genus
Delphinus. Teeth mammilliform.

Species. Inia Boliviensis ; (Fred. Cuvier,
Cetacés, pl. x, bis, and xi, cranium) ;
inhabits the great rivers of South Ame-
rica.

Genus, Puocana. Rostrum short, broad.
Teeth conical or compressed.

Ex. Phocena communis, the common
Porpoise; Phocena orca, the Grampus ;
Phocena globiceps, L’Epaulard, Cuv.
Phocena leucas, the Beluga,* &c.

The following genera seem to form the types
of as many distinct families of Zoophagous
Cetaceans.

Genus Monopon. Rostrum short and
broad. No other ¢eeth save two in the
upper jaw, in the form of tusks, situated
horizontally, and both of which continue
in the rudimental condition in the female,
while in the male one projects far be-
yond the jaws in the line of the axis of
the body.

Ex. Monodon monoceros, Linn. The
Narwhal.

Genus Hypreroopon. Rostrum of mo-
derate length, extending abruptly from
a very elevated cranium. Two small
teeth in the lower jaw; small callous
tubercles on the palate.

Ex. Hyperoodon Dalei ; the great Bottle-
nose Whale of Hunter.

Genus Pratanista. Rostrum very long
and compressed, enlarged at the extre-
mity. Teeth numerous; in both jaws
conical and recurved. Cranium enlar-
ged by osseous processes. A ccecum.

Ex. Plutanista Gangetica. The Gangetic
Dolphin.

* This species has no dorsal fin, and on that ac-
count has by some naturalists been regarded as
forming the type of a distinct genus, under the
name of Delphinapterus.

564

B. With the head o
equalling one-thir

body.

Family L CATODONTIDE. Teeth nu-
merous, conical, but developed only in
the lower jaw. External nostrils or
blow-holes confluent ; no cecum.

Genus Caropon. No dorsal fin.

Ex. Catodon macrocephalus ; Physeter
macrocephalus, Shaw. The great Sper-
maceti Whale.

Genus Puysrrer. A dorsal fin.

immoderate size,
the length of the

Ex. Physeter Tursio, Linn. The High- :

finned Cachalot, Shaw.

Family BALE NID. No teeth; their
place supplied by the plates of baleen
or whalebone attached to the upper jaw.
Blow-holes distinct ; a cecum.

Genus Batanoprera. <A _ dorsal fin;
pectoral integument plicated; baleen-
plates short. (See fig. 259.)

Species. Balenoptera Boops, Cuv.; the
Jubarte or great Rorqual.

Balenoptera rostrata, Lacép.; the Piked
Whale of Sibbald and Hunter, sus-
pected by Cuvier to be the young state
of the Balenoptera Boops.

Balenoptera Musculus, Cuv.; the Me-
diterranean Rorqual.

Balenoptera Antarctica, Cuv.; the South-
ern or Cape Rorqual.

Genus Batana. No dorsal fin; pectoral
integument smooth; baleen-plates long.

Species. Balena mysticetus, Linn. The
great Whalebone Whale of Hunter ;
great Mysticete.

Balena Australis,Cuv. TheCape Whale. ]

Orcans or Morion.—Swimming is the
ag mode of progression of the Cetaceans,

ut the Phytophagous species appear to have
the power, in order to feed upon marine plants,
of crawling and walking at the bottom of the
sea by means of their anterior members, which
in other Cetaceans are exclusively natatory
organs.

The head, in all, has so little mobility, that
its axis can be but slightly altered, without
that of the body altering also.

In the form and composition of the skull
the Cetaceans of both tribes present many im-
portant differences, as compared witth other
mammiferous animals. In the Herbivorous
genera the bones are dense and massive, and
where they are not anchylosed their connection
is of a loose kind. Inthe Dugong the skull is
more especially remarkable for the large size of
the intermaxillary bones (a, a, figs. 246, 247),
which extend backwards as far as the middle
of the temporal fosse, and are bent down ante-
riorly over the symphysis of the lower jaw, so
as to terminate nearly on a level with its infe-
rior margin. This extent and shape is required
in the Dugong for the lodgement of the perma-
nent incisors (b,b), which are developed to a
large size, one in each intermaxillary bone,
and consequently the nostrils are placed much
higher and further from the mouth than in the
Manatee, in which, in consequence of the small
deciduous incisors having no successors, the

-CETACEA.

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sas ne
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7

intermaxillary bones are of much smaller size. —
The form of the bony aperture of the nostrils
(c, fig. 247) inboth the Dugong and Manatee is _
a large oval, which in the Dugong, as in the
typical Cetaceans, is directed upwards. The

entire cranium, and especially the frontal bones —

CETACEA.

aN) b

Skull of the

(d,d), are consequently gg shorter
than in the Manatee. The processes of the
frontal bone, which form the superior boundary
of the orbits, are thinner and more rugose in
the Dugong; the portion of the superior max-
illary bone, which serves as the floor of the
orbit, is narrower; the malar bone (e, e, figs.
246, 247), which forms by its curvature the
anterior and inferior margins of the orbit, is
more compressed and descends lower down.
The lachrymal bone, which is situated at the
anterior angle of the orbit (/; fig. 246), is of
larger relative size than in the Manatee; but,
as in that species, it is imperforate. The zygo-
matic process of the temporal bone (g, figs.
246, 247), which, in the Manatee, is propor-
tionally thicker than in any other animal, is of
more ordinary dimensions in the Dugong, bein
more compressed, and extended further back-
wards. ‘The connexions of the bones of the
cranium are the same in both these herbivorous
species. The parietal bones (A, fig. 247) are
evelo in the foetus, as usual, each from a
distinct centre of ossification; but, what is
very remarkable, the ossification of the inter-
parietal bone also proceeds from two lateral
and symmetrical points: these four, originally
distinct bones, are, however, very early anchy-
losed together, and also to the superior occipi-
tal bone, which latter junction takes place be-
fore the three other elements of the occipital
bone have coalesced. The parietal criste are
widely separated from each other. The occiput
is narrower, and its crest is less marked than
in the Manatee. In the interior of the cranium
we may observe that there is no bony tento-
rium, and that the cribriform plate of the
ethmoid is reduced to two simple depressions,
widely separated from one another, and termi-
nating anteriorly in two or three small foramina.
There is no sella turcica for the pituitary gland.

565

The optic foramen presents the form of a long
and narrow canal.

The lower jaw (i, fig. 246) corresponds in
depth to the curvature and length of the inter-
maxillary bones, and is bent downwards at the
symphysis in a corresponding direction, pre-
senting on the anterior surface of this part three
or four rough and shallow alveoli, in two of
which Sir Everard Home* discovered a small
rudimental incisor.

The skull of the true or Zoophagous Ceta-
ceans is characterized by the great breadth and
elevation of the cranium, by the almost verti-
cal direction of the nasal passages, by the de-
pressed position of the orbits as compared with
the bony nostrils,—a character which is still
more marked in these than in the herbivorous
species; and, lastly, by the extreme prolonga-
tion of the oral or labial portions of the inter-
maxillary and maxillary bones. The superior
maxillaries (g, g, fig. 268) are also developed
posteriorly so as to rise anterior to the frontal
bones, over which they are expanded, extending
as far as the level of the nasal bones, which
form almost the summit of the cranium. Such
at least is the general configuration of the skull
in the Delphinide, which constitute the largest
family of the Zoophagous tribe.

In the Phocena globiceps, of which the skull
is represented in fig. 248, the cranium is very

Wy ii

LODO

Skull of the Roundheaded Porpesse ;
Y Paions globiceps.
convex behind; the occipital crest (a, a) sur-
rounds the upper part and descends on each
side to the middle of the temporal criste: the
posterior convexity is not formed by the oeci-
pital bone alone, but also by the interparietal
and parietal bones (b, 6), the whole being an-
chylosed together at a very early period. The
parietal bones descend, as in the human sub-
ject, between the temporal and the frontal (c,c ),
and reach the lateral ala of the posterior sphe-
noid. As the parietals terminate behind the

* See Pl. xiv. Philos. Trans. 1820.

566

transverse superior cranial or occipital ridge,
and the superior maxillary bones approach very
close to the same part, the frontal bone seems
to be represented by a very narrow osseous
band traversing the cranium from right to left,
and dilating at each extremity to form the roof
of the orbit (cc). But when the maxillary
bones which have extended over the whole
anterior part of the cranium are raised, the
frontal bone is then seen to be of much larger
size than the external appearances indicate.

The two nasal bones (d, d) are in the form
of oblong rounded tubercles, set deeply in
two depressions in the middle of the frontal
bone, and in front of which the nasal passages
(e, e) are continued vertically downwards.
The two intermaxillaries (f, f) form the exter-
nal and anterior margin of the nasal apertures.
The cribriform plate of the ethmoid consti-
tutes the posterior wall of the nasal passages;
and in this plate there are three or four small
perforations. The remainder of the circum-
ference of the bony nostrils is formed by the
maxillary bones, of which a small part appears
at g: their septum is the vomer, which is
ioined to the ethmoid as usual.

The malar bone is an irregular flattened bone,
which assists the frontal in forming the orbit,

and, like it, is covered by the maxillary bone: .

it sends backwards a long and slender process,
which articulates with the zygomatic process
of the temporal bone, and forms the only
bony boundary of the lower part of the orbit.
The zygomatic process of the temporal bone is
united to the post-orbital process of the frontal,
bounding the orbit posteriorly; and thus the
zygomatic arch is exclusively formed by the
temporal bone: this bone terminates at the
temporal ridge, having but a small extent of
development on the side of the cranium, and
not entering at all into the composition of the
posterior convex surface. At the base of the
cranium the basilar and the lateral occipitals
develop expanded plates, which join the ptery-
goideal ale of the sphenoid, and a lamina of
the temporal bone, to which the petrous and
tympanic bones have a ligamentous attach-
ment. The parietal bones also extend behind
the temporals, to aid in completing the basilar
walls of the cranial cavity, so that the temporal
bone is almost excluded from entering into the
composition of the cranium, serving merely to
close some small vacancies left by the parietals :
this structure is of great interest, as we perceive
in it the commencement of that displacement
of the temporal bones from the cranial parietes
which is characteristic of the small-brained and
cold-blooded classes of Vertebrata.

The differences between the Dugong and
Manatee in respect to the structure of the
cranium, we have seen to resolve themselves
almost entirely into the expansion and elonga-
tion of the intermaxillary bones in relation to
the tusks, which they are destined to support in
the former animal; and we shall find on a com-
parison of the skulls of the Delphinide toge-
ther, that they also differ from one another,
chiefly in the forms and proportions of their
maxillary and intermaxillary bones.

CETACEA.

The Delphinorhynchi are characterized, first,
by an extremely narrow rostrum, the h of
which is four times greater than that of the
cranium ; secondly, by the anterior curvature
of the ior extremities of the intermaxil-
laries, which, as it were, draw forwards in the
same direction the maxillary, the frontal, and
even the occipital bones ; thirdly, by the posi-
tion of the nasal bones, which are sunk in
between the frontals and _ intermaxillaries ;
fourthly, by the very diminutive size of the
temporal fossz.

The Delphini, properly so called, have also
a narrow rostrum, but its length is scarcely
three times that of the cranium ; the posterior

<
‘

extremities of the intermaxillary bones, toge-

ther with the maxillary and frontal bones, are
raised, but not bent forwards; the temporal
fosse in some species are as diminutive as in
the Delphinorhynchi, but in others gradually
recede from that character, and approach, by
their expansion, to the form which they exhibit
in the next generic type, viz. the Inia.

The cranium in this genus, besides the great
extent of the temporal fossa, and the strong
crista which forms its superior border, is also
characterized by the shortness of the orbital
fossa.

In the Phocene the rostrum is as remarkable
for its breadth as it is in the Delphini for its
narrowness ; this results from the great lateral
development of the intermaxillary and max-
illary bones; but the antero-posterior extension
of the bones is diminished, and the length of
the rostrum does not exceed that of the cranium.

The Narwhals ¢( Monodon) manifest their
affinity to the Porpesses ( Phocena) by the
breadth and shortness of the rostrum, but differ
from that and every other genus of Cetacea in
the development of horizontal tusks in the inter-
maxillary bones, of which the left in the male
and both in the female remain concealed in a
rudimental state within the maxillary bones.

The cranium in the genus Hyperoodon, which
includes the Great Bottle-noseWhale of Hunter,
is at once distinguishable by the remarkable
vertical crest which rises from the middle of
the maxillary bones, the contour of which pro-
cess descends suddenly behind, but extends
more gradually and obliquely downwards an-
teriorly. The lower jaw in this genus has two
rudimental teeth at its anterior part.

Lastly, in the Gangetic Dolphin ( Plata-
nista) the cranium presents a marked resem-
blance to that of the Delphinorhynchus in the
length and narrowness of the rostrum, and in
the elevation and anterior curvature of its base;
but on pursuing the comparison in detail, the
Structure and composition of this part of the
skeleton presents several fundamental diffe-
rences, which at the same time indicate an
affinity to the Cachalots (Physeter). The —
most striking character in the cranium of the —
Platanista is presented by the maxillary bones, —
which, after having covered, as in the other
Delphinide, the frontal bones as far as the
temporal criste, give off respectively a large ©
Osseous expansion, which arches forwards and —
forms.a capacious vault above the spouting

CETACEA.

apparatus of the nostrils. In order to consti-
tute this part, one of the processes inclines
towards the other, so as almost to come in
contact with it for the two anterior thirds ; but
posteriorly they recede from one another to give
passage to the blow-hole. The cavity beneath
this singular bony pent-house is occupied by
an interlacement of numerous osseous pro-
cesses, and by a close and hard fibrous sub-
stance.*

If we suppose the cranium of a Dolphin
to be proportionally very much shortened, the
margins of the rostrum to be greatly expanded
and raised, so as to render its superior
surface concave; the supra-frontal portions
of the maxillary bones to be much developed
and the margins extended upwards, thus form-
ing an immense basin, at the bottom of which
lie the external orifices of the bony nostrils ;
if also the occipital crest in the Dolphin were
raised behind the maxillaries so as to aid them
in the formation of the bony cavity, in the
basis of which the parietals are almost con-
cealed, we should then have the skull of a
Cachalot. The rostrum in the Catodontide, not-
withstanding its immense size, is formed prin-
cipally by the maxillary bones, as the inter-
- maxillaries and the vomer constitute a compa-
ratively small part of the intermediate portion.
The nasal passages extend obliquely from below
upwards and forwards, but are of very unequal
dimensions, the one on the right side not
having one-fourth the breadth of that on the
left. A corresponding want of symmetry is
shown in the nasal bones themselves, and the
cranium generally; and this circumstance, it
may be remarked, characterizes in a greater
or less degree the skull in all the Zoophagous
Cetacea.

The skull in the Whalebone-Whales ( Bale-
nid@ ) is, however, the most symmetrical in its
general form; it is characterized by the great
relative predominance of the facial over the
eranial portion, by the narrowness of the ros-
trum, and the curvature of the rami of the lower
jaw, which each extend outwards, in a convex
sweep, far beyond the sides of the upper max-

567

illa, and converge to the symphysis, but with-
out meeting to form.a bony union at their ante-
rior extremities.

In the Mysticete, or common Whalebone-
Whale (of which a side view of the skull is.
given at fig. 249) the immense maxillary bones
(a, a) are compressed, and disposed each like
an expanded arch along the outside of the in-
termaxillaries (6) and the vomer; their inferior
surface has two facets separated by an interme-
diate longitudinal ridge, to the sides of which
the plates of whalebone or baleen are attached
(6, fig. 259). The intermaxillary bones are also
laterally compressed, and diverge from each
other posteriorly to form the long elliptical
bony outlet of the nostrils; this orifice is com-
pleted behind by the nasal bones, which are of
very small size, and are partially covered by
the frontal bones, which project forwards above
them in the form of two small points. The
tranverse portions of the frontal (c) and max-
illary (a* ) bones, which contribute to form the
orbits, extend obliquely backwards: the tem-
poral bone (d) is of an irregular quadrate
form, and extends much further backwards
even than the occipital condyles. The occipital
bone (e) advances forwards so as to cover
almost all the upper part of the cranium,
where it presents a general convexity. Each
ramus of the lower jaw (f) is convex exter-
nally, compressed and somewhat trenchant
both at the upper and lower margins. The
coronoid process, on which the letter is placed,
is in the form of a slightly raised obtuse angle ;
the condyloid process (g ) forms the large tube-
rosity behind. It is articulated to the glenoid
cavity bya mass of ligamentous fibres, and not
by a capsular ligament surrounding a synovial
cavity.

The vertebral column of the Cetacea does not
differ from that of other mammalia except in the
modifications demanded by their peculiar mode -
of existence. The cervical vertebre, of the
normal number of seven, with the exception
of the Manatee, are in general extremely thin,
and though in some species, such as the
Manatee, the Dugong (k, fig. 246), and the

Fig. 249.

4 Fora detailed account of the structure of the
skull in this singular fresh-water Cetacean, see
Cuvier, Ossémens Fossiles, v. pt. i. p. 298.

Platanista, they are-found free; others, as the
Dolphins and Porpesses, have the first two
commonly anchylosed together. In the Bale-

568

noptere the dentata is anchylosed at its upper
part to the third cervical vertebra. In the
Cachalots they are the six last vertebre which
are thus found united to one another, and in
the Whales, properly so called, or Balene, all
the seven are anchylosed. (See fig. 250.)

Cervical vertebre of a Whale, Balena Australis.

The dorsal vertebre (1, fig. 246), the number
of which varies according to the species, are
characterized by having their spinous processes,
bent backwards, elongated from the first to the
last, and equalled in length by the transverse
processes. Moreover, their posterior articu-
lating processes disappear after the first ver-
tebra, and the anterior ones soon cease to per-
form the functions of parts concerned in the
union of the vertebra to one another.

In fig. 251, which represents the eleventh
dorsal vertebra of the Cape Whalebone Whale,
a is the spinous; b, b, the two transverse,
which begin to lengthen from this point in the
succeeding vertebre; c,c, the anterior articu-
lating processes.

Fig. 251.

Dorsal vertebra of a Whale.

The lumbar vertebre (m, jig. 246), the
posterior limit of which it is difficult to deter-
mine in animals devoid of pelvis, have their
spinous (a, fig. 252) and transverse processes
(6) very long. The first are straight and
slightly inclined backwards.

As it is essential that the Cetaceans should
have the posterior part of their vertebral co-
lumn left free, to allow of the vigorous in-
flexions of the tail required in the act of

CETACEA.

Lumbar vertebra of a Whale.

swimming, none of the vertebre are anchy-
losed together or encumbered by a union with
posterior extremities, and hence there are none
which can be properly termed sacral, unless
we regard the sacrum as represented by the
single vertebra, (n, jig. 246,) to which, in the
Dugong, the pelvic bones are suspended. The
caudal vertebre may then be considered to
commence from this point. Most of these
vertebre (0, fig. 246) are further charac-
terized by the chevron bones, (p, jigs. 246,
253,) which at first are strong and well deve-
loped, but together with the other processes
gradually diminish and disappear towards the
extremity of the vertebral column, where the
centres or bodies of the vertebrz alone appear,
and present a depressed flattened form cor-
responding to the horizontal position of the
caudal fin, which characterises these air-breath-
ing inhabitants of the ocean.

Fig. 253 represents one of the anterior
caudal vertebre of the Cape Whale: a is the
spinous; 6 the transverse; c, c, the represen-
tatives of the an-
terior oblique pro-
cesses; p the in-
feriorspinous pro-
cesses, or chevron
bones.

To bones so lit-
tle mobile, and so

Fig. 253.

Caudal vertebra of a Whale.

*

rudimental as the —

neck in Cetace- —
ans, muscles pro-
portionately de-

. SPO re ae

;
r
Aa
E
_
;
A

&

‘
5

CETACEA,

ness and thinness, principally in those at-
tached to the atlas and the axis, are extreme;
and although those which proceed from the
other cervical vertebree may be better charac-
terized, their action, nevertheless, is not much
more extensive. —

The muscles of the back present no other
important modifications than their great deve-
lopment and their prolongation even upon the
coccygeal vertebree. Thus the longissimus dorsi
and the sacro-lumbalis are attached anteriorly
to the skull, and posteriorly transmit their ten-
dons, the first to the end of the tail, the second
to all the transverse processes of this part of
the spine, associating in this way the move-
ments of the back with those of the tail. As
_to the muscles peculiar to the tail, besides those
which belong to this organ in all Mammals
where it exists as a moveable organ, there are
besides, in the Cetaceans, 1st, the antagonists
_ of the sacro-lumbalis below the transverse pro-
cesses; 2nd, a levator caude, which takes its
rise above the five or six dorsal vertebra, under
the longissimus dorsi, and often in this part
blends with it; it then extends freely as far as
the extremity of the tail, where the two muscles
unite together again by their tendons; 3rd, a
depressor caud@, of great thickness, which pro-
ceeds from the pectoral region, and spreads its
tendinous processes upon the ribs, distributes
them laterally to the transverse processes, and
below to be inserted into the chevron bones
along the two posterior thirds of the tail; 4th, a
muscle which comes from the rudimental bones
of the pelvis, and is inserted into the chevron
bones of the anterior portion of the tail; 5th,
the great recti muscles and the obligui ascen-
dentes, which, proceeding from the abdomen,
attach themselves behind to the sides of the
base of the tail.

It is in consequence of this great aggre-
gation of muscles, which are developed in
unexampled proportions as compared with
other ccs, that the tail of the Cetaceans
acquires the prodigious strength which it pos-
-sesses, and by means of which these gigantic
animals propel themselves with so much faci-
lity and impetuosity through the water, and
So readily ascend to the surface to respire,
and again seek protection in the deep abysses
of the ocean.

The sternum (q, fig. 246) is short and large.
Tn the Dugong it is composed of five pieces ;
in the Dolphin, the Porpesse, and the Pla-
tanist, it is generally composed of only three;
in the Whales it consists of but one. In the
subjoined figure (fig. 254) from the Bale-
noptera Boops, the
sternum is deepl
notched behind, and

Fig. 254.

its exterior or under
surface.

The ribs of the
Cetaceansarechiefly
remarkable for their
great curvature, but
differ in their rela-

/
_ tive length, thickness, and mode of connection.
P- VOL. 5.

has a large ridge on

569

Their thickness and the density of their tex-
ture is most remarkable in the Herbivorous
Species, especially in the Manatee. In the
Dugong, which has eighteen pairs of ribs
(r, r, fig. 246), only the first three have car-
tilages which join the sternum. In the Del-
phinide the first pair of ribs are articulated at
their sternal extremities to the anterior angles
of the first bone of the sternum; the second
pair join the sternum between the first and
second bones; the third between the second
and third, and the fourth, fifth, and in some
species the sixth pairs of ribs are joined to the
third bone of the sternum; the sternal portions
of these ribs are ossified. The anterior ribs
are articulated at first by a head to the ver-.
tebral centres, and by a tubercle to the trans-
verse processes ; but as they extend backwards
the head disappears, and the ribs are attached
only to the extremities of the transverse pro-
cesses.

In the Balenide the first pair of ribs are
remarkable for their great breadth, especially
at the sternal extremity, and these alone join
the sternum. In the Balena Capensis the two
first, as well as the four last pairs of ribs, are
joined only to the transverse processes of the
vertebre. .

The depressors and elevators of the ribs ap-
pear to possess nothing particular, and the
same may be said of the diaphragm and the
muscles of the abdomen ; but in regard to the
movements of these parts, we must remember
what M. Mayer says of the muscular fibres,
which encircle closely the lungs, and which
take part in the actions of inspiration and
expiration.

Mr. Hunter observes that, ‘* as the ribs in
this tribe do not completely form the cavity
of thé thorax, the diaphragm has not the same
attachments as in the Quadruped, but is con-
nected forwards to the abdominal muscles,
which are very strong, being a mixture of
muscular and tendinous parts. The position
of the diaphragm is less transverse than in the
Quadruped, passing more obliquely back-
ward and coming very low on the spine,
and high up before, which makes the chest
longest in the direction of the animal at the
back, and gives room for the lungs to be con-
tinued along the spine.” ]

The anterior members in the Cetaceans do
not essentially differ from those of the other
Mammalia, but they undergo, in these animals,
very great modifications.

In the shoulder they are entirely devoid
of clavicles. Their scapula is very large in
general, but varies in this respect according to
the species. In the Herbivorous Cetaceans, as
the Dugong (s, fig. 246), the anterior angle is
rounded, the posterior is extended backwards,
and the posterior margin or costa is concave.
The spine is prominent, and so placed as
to divide the dorsum of the scapula into a
supra-spinal and infra-spinal depression. The
acromion is pointed, but much less elongated
in the Dugong than in the Manatee. The
coracoid process is also more pointed in the
Dugong.

2P

570

In the Zoophagous Cetaceans the spine of
the scapula does not project much. The
supra-spinal fossa is reduced to a mere groove
in the common Dolphin, and entirely dis-
appears in the Gangetic species ( Platanista ) ;
the coracoid process does not exist in this last
dolphin; and the same absence is found in
the Balenida, whilst it is seen in the common
Dolphin and the Cachalot. Lastly, the acro-
mion appears always to exist, but with a
different development, in different species.
In the scapula of the Whalebone Whale (4,
Jig. 255) it is marked a. The articular or

Fig. 255.

Kan WWiiiaaaaes

!
a

\
iY

AN \

Bones of the anterior fin of a Whale,
Balena Mysticetus.

glenoid cavity (b) is proportionally larger in
this species than in the Spermaceti Whale.
The muscles of this part of the anterior mem-
ber present some remarkable modifications, but
with which we are only acquainted as they
exist in the common Dolphin. Thus the
serratus magnus does not extend as far as the
eervical vertebre, and ends at the ribs; the

CETACEA. | Boe —.
pectoralis minor, instead of descending on the —

ribs, is directed towards the anterior extremity
of the sternum. .

The rhomboideus (a, fig. 256) is not attached
to the ridge of the spine, but extends along the ;
superior edge of the scapula; the ¢rapezius
covers the scapula and has no clavicular pro- _
longation. 12h

The levator scapule (b, fig. 256) is attached
to the broad transverse process of the first
vertebra, and spreads itself over all the ex- .
ternal surface of the scapula. 7

The rest of the anterior member is com- ;
posed of the humerus, the radius, the carpus,
the metacarpus, and the phalanges.

In the Dugong the humerus (¢, fig. 246)
is much shorter and thicker than in the Ma-
natee, and the deltoid ridge is more prominent.
In the true Cetacea the humerus is always
very short. In the Whalebone Whale (B,
Jig. 255) its length is scarcely double its
breadth ; its head is hemispherical and almost
parallel to the axis of the bone. The lower
extremity is divided into two planes slightly
inclined for the ulna and radius.

The cubitus and the radius (v) are also very
short, and are anchylosed (u, fig. 246) together
at both extremities in the Manatee and the
Dugong, but they retain in these Cetaceans
the rounded form which is peculiar to them in
the other Mammalia. In the spouting Ceta-
ceans they are compressed, and are united by
means of fibro-cartilage with the humerus and
the carpus. The olecranon varies in size.
In the great Whale it rises in but a small de-
gree, while in the Spermaceti Whale it is de- .
veloped in the form of a hook. The radius ;
(C, fig. 255), which is broader than the ulna
(D, fig. 255), is dilated at its lower ex-
tremity.

The bones of the carpus are very much
flattened, and of an hexagonal form; they are
less in number than in Man, but the number
varies according to the species. The Manatee
has six, the pisiform being wanting. The
Dugong has four (w, fig. 246), of which two
are in the first row corresponding respectively
to the radius and ulna, and two in the second
row, the external one supporting the metacar-
pal bones of the pollexand index, the internal
bone supporting the medius and annularis;
the ulnar or little digit is supported by the
ulnar carpal bones of both the first and second
row. The pollex (2, fig. 246) is reduced, as
in the Manatee, to a small pointed meta-
carpal bone. The common Dolphin has only —
five metacarpal bones; the Whale has seven :
of these four are in the first row, and three in —
the second (E, fig. 255). The metacarpals-
(F, fig. 255) are five in number, Hat=
tened, and have the general form of phalang
The phalanges in the Zoophagous Cetacean:
partake of the flattened form of the bones ¢
the metacarpus. Their number increases
each finger, comparatively with the norm
number, sometimes very much so; and 1
many cases there are are
cartilaginous. The pollex (G 1, fig. 29
in the great Whale ibs two bones; the ind

jo om
J

CETACEA.

Muscles of the anterior fin of a Dolphin.

e. Sterno-mastoideus. = é
f Costo-humeralis or latissimus dorsi.
g- Portion of pectoral.

a. Rhomboideus.

6, Levator scapulz.

c. Infra-spinatus.

d, Humero-mastoideus.

(2) four, the digitus medius (3) five, the annu-
laris (4) four, and the digitus parvus (5) three
bones; all are terminated by a cartilaginous
dilatation: they form collectively a large and
short paddle, obliquely rounded.

The muscles which characterize the arm of
the Mammalia exist generally also in the
Dolphin, and doubtless in the other Cetaceans,
but with modifications which have not been so
satisfactorily described as could be wished.
The great pectoral muscle (a part of which is

h. Splenius.

seen at g, fig. 256) presents the sternal portion,

which is called the musculus communis, or mus-
cle common to the two arms. The Jatis-
simus dorsi (f, fig.256) is represented by a little
muscle, the digitations of which are attached
to the ribs; the supra-spinatus and infra-
spinatus are nearly of equal size, but the sub-
scapularis is very large. The coraco-brachialis
is very short. The muscles of the other parts
of the arm, that is, of the fore-arm and hand,
in a rudimental state, and seem to

exist less on account of the movements of the
to which they are attached, than to shew

e analogy of the anterior members of the
Cetaceans with those of other Mammalia.

[ In our dissections of the common Porpesse
we have found the supra-spinalis of small size,
corresponding to the size of the supra-spinal
fossa. It is covered by the deltoid muscle (7).

The infra-spinatus (c) is consequently of much

r size, but is a thinner muscle: behind
this muscle is seen the teres major (k) and
minor (1).] mre
_ As we have already said, the posterior extre-
_ mities are wanting ; all that remains of them are

the rudiments of a pelvis. These rudiments
are found in the Dugong to be composed of
two pairs of bones (y, fig. 246) united two
and two, and end to end by a cartilage, and

; 5714

attached by a carti-
lage also to one of
the vertebrae. In the
Dolphins they con-
sist of two little,
long, thin bones
which are lodged in
the flesh, one to the
right and the other
to the left of the
anus. Inthe Whales,
at the extremity of
each of these bones
(4,4, fig 257), which
are regarded as ilia,
a second (6) is found
articulated, smaller,
and curved ; thecon-
vexity of which is
external, and might
represent a pubis, or
an ischion; it seems
to correspond to the
second of these bones
in the Dugong.

We perceive that
the internal construc-
tion of the organs of
movementin the Ce-
taceans doesnot vary
in the different spe-
cies except by mo-
difications the im-
portance of which
we are not able to
appreciate. The dif-

Fig. 257.

ferences in __ their
exterior structure,
moreover, do not ap-

pear to exercise any
Influence over their
mode of living; for
the chief of these consists in the Manatee
having nails to the ends of its pectoral fin,
which correspond to the fingers, of which it
is in part composed ; and in its tail being oval
instead of being extended laterally into two
wings.

We have in no way considered as forming
part of the organs of movement, the protu-
berances which are seen upon the back of
some species of spouting Cetaceans, some-
times in the form of a hump, and sometimes
like a fin, more or less elevated. These pro-
tuberances, in fact, are nothing more than »
simple gibbosities, simple prolongations of the
skin, filled with dense cellular tissue and fat,
and resembling more or less a fin, but devoid
of any independent movement, and without any
direct connection either with the vertebre of
the back or with the muscular system.

Digestive organs. — The alimentary appa-
ratus is one of those, which, in many of its
parts, presents the most important modifica-
tions in the Cetaceous Order.

The three genera into which the Herbivorous
Cetaceans are divided, are characterized by
three systems of dentition fundamentally dif-
ferent. The Manatees have molares with dou- -
2P 2

Pelvis of the Mysticete
Whale.

572

ble or triple ridges, and with the
root distinct from the crown, pre-
senting a remarkable resemblance
to those of some of the Pachy-
derms, as the Hippopotamus. The
Dugongs have simple elliptical
molares, the crown of which, before
it is worn, presents two slight fur-
rows, which are entirely effaced
by age. They are without fangs,
properly so called; and in the up-
per jaw are found two long tusks,
of which the other Cetaceans of
this family are destitute. The
Rytine have no molares at all; these teeth
are replaced by a horny plate in the middle
of each jaw, a structure which seems to connect
these animals with the Whalebone Whales.

The tongue is short and but little susceptible
of movement.

The os hyoides is characterized in the Cetacea
chiefly by the slight degree or total absence
of connection with the larynx, resulting from
the elevated position of this organ required by
its peculiar relations with the posterior nares.

In the Herbivorous order the Dugong pre-
sents a simple form of the os hyoides; the
posterior cornua soon anchylose with the body,
but send no ligament to the thyroid cartilage.
The anterior cornua generally remain cartila-
ginous, and form the medium of union be-
tween the body or basi-hyal, and the large and
long styloid processes. In the Delphinide the
body and posterior cornua of the hyoid bone
are of a flattened form. In the Balenidg, as
the Piked Whale or Balenoptera, the body
(a, fig. 258) is a cylindrical bone, extended

transversely, and is slightly curved backwards
and upwards; its middle portion supports an-
teriorly two processes (b, b) resembling the
base of the anterior cornua in the Ruminants ;
besides these there are, in this genus, two
rounded tubercles on the posterior margin op-
posite these processes. The styloid bones
(c, c) are cylindrical and slightly curved in
two directions; they are joined by cartilage
on each side to the occipital protuberance
which represents the mastoid process.

The muscles which protrude and retract the
tongue are extremely simplified in the Ce-
taceans ; the retractors are represented by a
single pair, analogous to the stylo-hyoidei, the
fibres of which pass from the posterior margin
of the stylo-hyal bones to the body of the
hyoid. The stylo-glossi pass from the anterior
and superior margin of the styloid process to
their insertion. The hyoglossi arise from the
middle of the convexity of the os hyoides.

Tongue and Baleen-plates 0

CETACEA.

re a — eo on Ms

—— 7

the
Balenoptera Boops.*
The genio-glossi pass backwards and inwards -
from the anterior contour of the lower jaw.
The tongue itself corresponds to the form
of the space included by the rami of the lower
jaw, and is consequently of great size in the
Cachalots and Balenide, rising in the latter
like an immense cushion (a, fig. 259), into
the space between the lamine of baleen (6),
and affording a great quantity of the finest oil.
In the figure it is represented in the Piked
Whale, but probably preternaturally enlarged
and raised by the extrication of gas caused by
putrefaction. It is thick, and its free extremity
is generally short, but this is less remarkable
in the Phytophaga than in the Zoophaga. In
the Dugong (fig. 260) the upper surface of
the anterior part of the tongue (@) is beset with
cuticular spines, and on each side of its basis
there is a remarkable horny retroverted pointed
process (0, 6).

Fig. 260.

Tongue of ihe Dugong.

In the Porpesse the surface of the tongue is
soft and smooth, and very flat superiorly; the
anterior margin is fringed by a number of short
irregular processes (a, fig. 265).

The salivary glands are reduced to the most
rudimental condition. ;

In the Phytophagous Cetaceans the stomach ~
is separated into two portions (fig. 261); one, —
the cardiac (a), very large, the other, the
pyloric (6), of narrower calibre, by a contrac-

tion (c) giving origin to two prolongations —
(d, d), which are tubiform in the Dugongs, —
and of a pouch-like form in the Manatees.
In both species there is a gland at the
cardiac extremity of the stomach (c), which it
the Dugong, Sir Everard Home (from whose
memoir the figure subjoined is taken) describe
as “forming a round mass, as in the Beavel
The orifices of these glands are small, and

* From Fr. Cuvier, Cetacex, pl. 20. © ")

CETACEA.

Fig. 261.

Stomach of the Dugong.

covered over with a membranous bag, which
has only one large aperture. The glandular
mass is divided into two portions.”* Thus the
stomach of the Dugong presents peculiarities
which are met with singly in animals of the
Cetaceous, Pachydermatous, and Rodent Or-
ders. Like the stomach of the Whale it is
divided into distinct compartments ; like the
stomachs of the Hippopotamus and Peccary
_ it has coecal pouches superadded to and com-
municating with it; and like those of the Dor-
mouse and Beaver its cardiac compartment is
provided with a glandular apparatus: (fis the
esophagus, g the intestine.)

e cecum is simple and cordiform in the
_ Dugong (fig. 262), but is of more irregular

Fig. 262.

td Caecum of the Dugongq.

figure and bifurcated in the Manatee. The Ry-
tina appears also to possess a stomach divided
into two portions, of which the cardiac is also
larger than the pyloric; and it has a very large
cecum, divided on its internal surface into

* Phil, Trans. 1820, p.317.

573

numerous cells. A
gland,remarkable for
its size, is also found
in the first portion of
the stomach of this
species. No sub-
stances but fuct have
ever been found in
the alimentary canals
of these animals.

The Zoophagous
Cetaceans _ present
still greater differ-
ences in their alimen-
tary organs than the
Phytophaga. In the
Dolphins the teeth,
which are generally
simple and conical,
or compressed in
both jaws, vary con-
siderably in number,
and often remain concealed in a rudimen-
tary state in the gums. In the Cachalots
they are only found in the lower jaw; are
simple and oviform; and their number ap-
pears to be in no way certain. The Whales
have no true teeth, but at each side of their
palate grow, transversely, horny plates, named
baleen (the whalebone of commerce), pro-
vided on their inner edges with fringe-like
beards, amidst which, as in the meshes of a
net, the animals which form their food are
retained.

[The structure, forms, and disposition of the
teeth having beeri given in the characters of
the different genera of Cetacea, we have here
only to add a few words on the subject of the
baleen-plates which form their substitutes in
the family of Balenide. Each of these plates
consists of a central, coarse, fibrous, and two
exterior or lateral compact layers; the first
extends beyond the latter, so that the plate
terminates at its lower or free-extremity in a
fringe, and in looking upwards into the mouth
of a Whale when all the baleen-plates are in
situ, only their fringed extremities are seen.

The base of each baleen-plate has a conical
cavity, which is fixed ope a pulp of a cor-
responding form, buried deeply in the firm
vascular substance of the gum which covers
the under surface of the maxillary and inter-
maxillary bones; the sides of the base of the
baleen-plate are firmly attached to white horn
laminz of the gum, which are reflected from
one plate to another, and from which the ex-
ternal compact layers of the baleen are con-
tinued: the pulp appears to be subservient to
the secretion of the central coarse fibrous part
alone)

Nothing can differ more, or indeed be more
contradictory than the descriptions which have
been given of the stomachs of the Zoophagous
Cetaceans. In many of the species the struc-
ture of this part is unknown. It has been
more or less fully described in the Delphino-
rhynchus micropterus, the common Dolphin,
the Small Bottle-nose (Delphinus Tursio ),
the common Porpoise, the Grampus, the

574

Phocena globiceps, the carinated Porpoise,
the Béluga, the Platanist, the Narwhal, the
Great Bottle-nose or Hyperoodon, and the
Piked Whale ( Balenoptera). There is no doubt
that the stomachs of all these animals are very
complicated ; and although it may be more
than probable that they do not resemble each
other in their composition, it is to be presumed,
however, that it is to their complication we must
attribute the essentially different descriptions
which have been put forth on this subject.
What authorizes this supposition is the di-
versity of opinions which exists relative to
the number of the stomachs of the common
Dolphin and common Porpoise, some
counting only three, others four, others five,
and others six, &c. Now it is certain that
these differences of number proceed simply
from the manner in which this organ is viewed.
When it is only judged of by its exterior, and
its globulous parts alone are called stomach,
only three or four can be reckoned; and then
the more or less tubular passages, situated
amongst those more or less spherical cavities,
are considered as mere intercommunicating
canals. But if the interior of these stomachs
be studied, it is seen that several amongst them
have a special organization, and are separated
from one another by small openings, which do
not invariably establish a direct communica-
tion between them: hence the tubular parts
cannot be considered as simple passages, but
must necessarily be admitted as essential
parts of the stomach, which, like the others,
impress their peculiar action upon. the food.
It has also been the case that the dilated sac
into which the biliary and pancreatic juices
are poured, has not been admitted as belong-
ing to the stomach; but besides its not being
without example that in Mammalia the bile
may be poured immediately into the stomach,
the difference in the nature of the membranes
ought to suffice for deciding whether the part
which receives these secretions belongs or not
to the duodenum. Now in the Dolphins it is
evidently at the termination of the last stomach
that their duct opens. In this state of things
it is impossible to decide with precision in
what particulars the Zoophagous Cetaceans differ
from one another in the structure of the sto-
mach. It appears, however, that this organ
in the common Dolphin, the common Porpoise,
the Globiceps, and the Platanist, is formed upon
the same type, and is composed of five parts ;
and if they differ one from another, it is only
by modifications of secondary importance. If
to these facts we add what Meckel states re-
specting the Narwhal, in which he recognizes
five stomachs, and what Hunter says of the
Grampus and Piked Whale, in which he like-
wise found five, we have three species more
to add to the first. In fact, when we consider
that only three or four stomachs have been re-
cognized in the Carinated Porpesse and the
Beluga, which are true Phoceng, and that
Baussard saw three, and Hunter seven in the
Hyperoodon (Great Bottle-nose Whale), we
believe ourselves authorized in thinking that
these differences depend entirely upon the

CETACEA.

manner in which this organ is viewed, and we
consider it very probable that the number of
stomachs in these Cetaceans, as in the others,
is five. However, from this small number of
facts, and from all the conjectures with which
we have been obliged to approach the subject,
we shall draw no precise conclusion as to the —
structure which may be common to the Zoo-
phagous Cetaceans. But this undoubted great
complication of the stomach in animals which |
are nourished with the most animalized food,
isan anomaly the cause of which it would be
very important to investigate; for from the
ascertained facts which we have to reason from,
weare not led by any analogy to an explanation
of this subject.

In our examinations of the stomach of the
Porpesse (fig. 263), we have not been able to

Fig. 263.

Stomach of the Porpesse. ‘
distinguish more than four compartments. —
This complex digestive organ, besides the
structure of the internal surface, differs from —
that of the Ruminant Animals in the compara-
tively small size of the first cavity, and the mode ~
of inter-communication of the other compart-—
ments, which succeed one another, and are
not appended to the extremity of the cesopha~
gus: instead, therefore, of the cesophagus —
communicating with all the four cavities, it
opens only into the first, and consequently no —

CETACEA.

rumination can take place. The first cavity
is continued in the same line with the cesopha-
gus, having the same structure, and not being
divided from it by any sensible constriction ;
its commencement is indicated by the orifice
leading into the second stomach, beyond which
orifice it is continued in the form of a dilated
ovate cavity (a). It is lined with a cuticle,
and its inner surface is beset with small ruge.
A number of large irregular projections sur-
round the aperture leading to the second ca-
vity, and are calculated to prevent the passage
into the second of any substances save such
as are of very small size. Notwithstanding
the nature of the lining membrane the di-
gestive processes are considerably advanced
in this cavity, which does not act simply as a
reservoir. Itis probable that the secretion of
the second stomach, which is highly glandular,
regurgitates into the first and assists in pro-
ducing the dissolution of the carneous parts
of the fishes, the remains of which are
usually found in it. The thick cuticular
lining terminates abruptly at the small ori-
fice leading into the second stomach (6).
The interior of this cavity presents a series of
close-set thick longitudinal wavy ruge, laterally
indented into one another. The internal layer
is thick and of a peculiar structure: according
to Sir David Brewster, “ it seems, in its wet
state, to consist of tubes or fibres perpendicu-
lar to the two membranes which inclose them,
and the upper surface of one of the membranes
is covered with hollows or depressions corres-
ns with the extremities of the tubes or
bres. A more minute examination, conducted
in a different way, proves these perpendicular
portions to be tubes. In order to.dry it, 1
pressed it between folds of paper, and the effect
of the compression was to press together nearly
all the tubes, and make A,
mass, of a dark brown colour ; but when it be-
came dry and slightly indurated, I drew it
out as if it had been India-rubber, and the
tubes opened, and the mass became white.”
The membrane next the cavity of the sto-
mach is perfectly smooth; the one external
to the fibres is a vascular and cellular tunic,
and is inverted by the layer of muscular fibres
continued from the preceding cavity. The
communication with the third stomach is near
the lower end of this cavity. The third com-
partment is a small round vascular cavity, into
which the second opens obliquely : it is lined
by a smooth and simple villous tunic. It is
not visible exteriorly, and does not exceed an
inch in length in the Porpesse, but in the
Hyperoodon is about five inches long. The
fourth cavity (c,c) is long and narrow, and
in a serpentine course almost like an
intestine; the internal surface is smooth and
even, but villous. It opens on the right side
into the duodenum (d), which is much dilated,
and, as in the human subject, is without valvule
conniventes at its commencement. The pylo-
Tus is a smaller opening than that between the
third and fourth cavities. ]
Some authors s affirmatively of a con-
siderable bladder, which in the Rorquals, after

e whole one dense |

575

death, comes up into the mouth and forces the
two jaws asunder. Now what is the nature of
this vesicular mass, of which other authors say
nothing? To what organic system does it be-
long? This has never been made a subject of
enquiry. It has been considered as belonging
to the respiratory system, or as an air-bladder
analogous to that of fish. Is it not more proba-
bly a portion of the-stomach distended by the
gases formed there ?

In general the Spouting Whales have no
coeecum. However, a trace of this gut has
been found in an oval elevation in the Plata-
nist; a coecum exists also in the Piked Whale
and in the Whale-bone Whale. The variations
in form or affinity of the spleen and the liver
appear to have no essential relation with the
forms of the stomach.

Mr. Hunter observes that “ there is a con-
siderable degree of uniformity in the liver in
this tribe of animals. In shape it nearly re-
sembles the human, but is not so thick at its
base nor so sharp at the lower edge, and is
romney not so firm in its texture. The right
obe (e, fig. 263) is the largest and thickest,
its falciform ligament broad, and there is a
large fissure (g) between the two lobes, in which
the round ligament passes. ‘The liver towards
the left (f) is very much attached to the sto-
mach, the little epiploon being a thick sub-
stance. There is no gall-bladder.” “ The
reco is a very long, flat body, having its
eft end attached to the right side of the first
cavity of the stomach: it passes across the
spine at the root of the mesentery, and near to
the pylorus joins the hollow curve of the
duodenum, along which it is continued, and
adheres to the intestine, its duct entering that
of the liver near the termination of the gut.”-—
Phil. Trans. 1787, p. 410.

The structure of the biliary organs has a
closer resemblance to that of Quadrupeds
in the Herbivorous Cetacea, and differs from
that above described in the presence of a gall-
bladder, besides some minor points.

In the Dugong the liver is a transversely-
oblong viscus, divided into three lobes with a
fourth small process at the root of the left lobe,
representing the lobulus Spigelii. It is as
usual convex towards the diaphragm, but rather
flattened than concave towards the viscera, the
anterior margin thick and rounded. Of the
three larger lobes the middle one is the smallest,
of a square shape, projecting forward, and as
it were overhanging the gall-bladder, which
is lodged in the middle of the inferior surface.
The ligamentum suspensorium is continued
upon the middle lobe, immediately above the
gall-bladder, the anterior margin of this lobe
being notched to receive it, and the remains of

‘the umbilical vein entering the liver an inch

above the fundus of the gall-bladder. The
two lateral lobes are more than double the size
of the cystic lobe, and of these the left is the
largest. Both these lobes are concave to-
wards the small middle lobe, which they
thus surround and conceal. The lobulus
Spigelii is of a flattened and square shape,

‘measuring one inch and a quarter in length

576

and one inch in breadth. The gall-bladder
is of an elongated form, about an inch in
diameter at the broadest part. It does not
receive the bile by means of a communication
between the cystic and hepatic ducts as in most
animals, but that fluid is conveyed directly
into it by two distinct hepato-cystic canals in
the same manner and situation as the ureters
terminate in the urinary bladder. The two
orifices are half an inch apart. on the same
transverse line, and at a distance of three inches
from the fundus vesice they are large, readily
admitting a full-sized probe. The common
ducts, of which they are the terminations, are
half an inch in length, and branch off into the
lobes on either side. The inner membrane of
the gall-bladder is rugous; it has a longer
investment of peritoneum than in man. Where
it ends it is difficult to say, as it gradually
diminishes in size after the entry of the above
ducts, and does not appear to be separated
from the cystic duct by any marked contraction
or valvular structure. The cystic duct is about
six inches in length, and two lines in diameter ;
dilates a little before entering the duodenum,
and as it passes between the coats of that intes-
tine the canal is provided with a reticular
valvular structure of the inner membrane,
which may probably supply the deficiency of
this structure in the preceding parts of the
duct.

Three vene cave hepatice from the three
lobes of the liver join the vena cava inferior at
the upper and posterior edge of the liver, which
is not, however, perforated by it as in most
quadrupeds. The vena porte, formed in the
usual manner, but deriving a very small branch
from the spleen, enters the fissure below the
gall-bladder.

Sir Everard Home takes no notice of the

pancreas ; Sir Stamford Raffies merely observes |

that it lay ‘ below the duodenum.’ It is
situated below and behind the pyloric cavity
of the stomach. Its length in a Dugong six
feet long we found to be seven inches; it was
obtuse and thick at the splenic or left end,
where its diameter was two inches, and gradu-
ally growing smaller towards the duodenum,
it terminated in one uncommonly large duct,
which was three lines in diameter and of great
length. On laying open this canal the orifices
of from twenty to thirty tributary ducts were
observable, which were two lines in diameter;
the coats of these ducts thick, and terminating
in flattened lobules.

The spleen, as Sir S. Raffles observes, was
very small, of a rounded form; its length in
the larger specimen four inches and a half, its
breadth in the middle one inch and a half, from
which it tapered to either end; its structure
finely reticular.

In the Piked Whale the spleen is single and
of small proportional size; in the Porpesse
this organ is remarkable for its subdivision into
distinct portions, of which one is generally
about the size of a walnut (Ah, fig. 263); the
others, to the number of four, five, or six (é, 2),
are of much smaller size.

The Spouting Whales always feed upon

CETACEKA.

living food. The Dolphins and Cachalots pur-

sue or catch fish principally, and large Mollusks,
whilst Whales prey upon the numerous little
Molluscous and articulated animals and Vermes
which swarm, it is said, in the northern seas,

and in the number of which are reckoned
crustaceans, cuttle-fishes, clios, medusas, sea-
anemonies, &c ; but in this respect a difference
must be made between the Balznoptere and

the Whales, properly so called ( Balene ), for
we are assured that the first also feed upon
fish, and are capable of swallowing much
larger animals than the latter.

Orcans or Crrcutation.—The researches
of the anatomist on the circulating system of
the Cetaceans have not hitherto been extended
to many species. In its essential parts it is
similar to that in other Mammalia. But the
peculiar nature of Cetaceans, and the great
modifications of their organs of movement,
have necessarily produced in this system, not
only modifications analogous to those of these
organs, but vascular developments exclusively
characteristic of these animals.

It is not known whether the Manatee pre-
sents anything particular in regard to the organs
of circulation, but the heart of the Dugong
(fig. 264) and of the Rytina is cloven by the

Fig. 264.

Heart of the Dugong.

deep separation of the two ventricles, a cir-
cumstance which adds an important link of
affinity to those already subsisting between
these animals.

Us the heart of the Dugong, the ventricles,
as Sir Stamford Raffles has correctly described
them,* are not completely detached from one
another. The auricles are of equal size and
of a rounded form. In the right auricle (a),
which receives a single superior cava, the —
coronary vein, and the inferior cava, there is
on the auricular side of the orifice of the —
latter vein a fleshy Eustachian valve, of the
size and form which, in such cases, is com-
monly seen in the human subject. The valve
of the foramen ovale has a reticulate surface
at the upper margin, but is entire and wy
perforate. The right ventricle (6), in the Du-—

* Phil. Trans. 1820, p.174.

CETACEA.

gong previously mentioned, which was six feet
in length, was three inches and a half long
and three inches broad at the base; the thick-
ness of its parietes one line and a half; the
carnee columne are few, and resemble those
in man. The tricuspid and mitral valves are
of the usual form and structure, but the latter
are broader than in man, measuring each one
inch three lines across the base. The diameter
of the orifice of the pulmonary artery (c) is one
inch and a half. The capacity of this vessel
is very great, according with the impediments
to the transmission of blood through the lungs
which must arise from the submarine habits
of thisanimal. In the left auricle (d ) the trans-
verse pectinated muscular bands are equally
if not more developed than in the right. The
trace of the foramen ovale is more evident on
this side the septum auriculare than in the right
auricle; it appeared as an oblique slit directed
whe about three lines broad, but was com-
etely closed.
The parietes of the left ventricle (e) are
half an inch in thickness; there is nothing
unusual in the mitral valve or the carnee
column connected with it; the inner surface
of the ventricle was as usual smooth below the
origin of the aorta (f/f). The breadth of the
semilunar valves here was ten lines, the dia-
meter of the orifice being one-third less than
that of the pulmonary artery. The ductus ar-
teriosus was completely obliterated.
The heart in the Dolphins and Whales does
not el to have Ratiactes any remarkable

u
P

modifications; but their arterial system pre- |

sents a very important one in the infinite
circumyolutions of arteries, and the vast ple-
xuses of vessels, filled with oxygenated blood,
which are found particularly under the pleura
and between the ribs, on each side of the spine.

[Of this remarkable structure, which was
discovered by Hunter, we here subjoin the
original description.

“ The general structure of the arteries re-
sembles that of other animals; and where parts
are nearly similar, the distribution is likewise
similar. The aorta forms its usual curve,
and sends off the carotid and subclavian ar-
teries.

“ Animals of this (the Whale) tribe, as has
been observed, have a greater proportion of
blood than any other known, and there are
many arteries apparently intended as reservoirs,
where a larger quantity of arterial blood seemed
to be required in a part, and vascularity could
not be the only object. Thus we find, that the
intercostal arteries divide into a vast number
of branches, which run in a serpentine course
between the pleura, ribs, and their muscles,
making a thick substance somewhat similar to
that formed by the spermatic artery in the Bull.
Those vessels, every where lining the sides of
the thorax, pass in between the ribs near their
articulation, and also behind the ligamentous
attachment of the ribs, and anastomose with
each other. The medulla spinalis is surrounded
with a net-work of arteries in the same man-
ner, more especially where it comes out from
the brain, where a thick substance is formed

577

by their ramifications and convolutions ; and
these vessels most probably anastomose with
those of the thorax. |

“ The subclavian artery in the Piked Whale,
before it passes over the first rib, sends down
into the chest arteries which assist in forming
the plexus on the inside of the ribs; I am not
certain but the internal mammary arteries con-
tribute to form the anterior part of this plexus.
The motion of the blood in such cases must
be very slow; the use of which we do not
readily see. The descending aorta sends off
the intercostals, which are very large, and
gives branches to this plexus; and when it
has reached the abdomen it sends off, as in
the quadruped, the different branches to the
viscera and the lumbar arteries, which are
likewise very large, for the supply of that vast
mass of muscles which moves the tail.

* In our examination of particular parts,
the size of which is generally regulated by
that of the whole animal, if we have only
been accustomed to see them in those which
are small or middle-sized, we behold them
with astonishment in animals so far exceeding
the common bulk as the Whale. Thus the
heart and aorta of the Spermaceti Whale ap-
peared prodigious, being too large to be con-
tained in a wide tub, the aorta measuring a
foot in diameter. When we consider these as
applied to the circulation, and figure to our-
selves that probably ten or fifteen gallons of
blood are thrown out at one stroke, and moved
with an immense velocity through a tube of a
foot diameter, the whole idea fills the mind
with wonder.” *

It is to be presumed, as has been done, that
this singular complication of vessels is caused
by the necessity in which the Cetaceans are
often placed of suspending their respiration,
and consequently the oxygenation of their blood, -
during a considerable time. These numeerous
arteries form, therefore, a reservoir of oxyge-
nated blood, which, re-entering the circula-
tion, supports life throughout, where venous
blood would only produce death. But how
this blood is sent to this general system of arte-
ries, or what is the peculiar force which acts
upon it to this effect, is a point on which we
are still reduced to the most vague conjectures.

* Phil. Trans. 1787. p.415. It must be supposed
that M. Breschet, who has recently written on the
arterial plexuses of the Cetacea, could only have
known the preceding description by extract or refe-
rence, or he would not have stated that the structure
in question had been ‘observée par J. Hunter, mais
indiquées trop sommairement pour pouvoir étre des
lors comptés au nombre des faits acquis a la sci-
ence,’ for we do not find in M. Breschet’s paper
any essential addition to the original account given
by our celebrated anatomist, either with respect to
the observation of additional facts, to their clearer
description, or to the physiological inferences de-
duced from them, It is agreeable to find that M. V.
Baer, whose observations on the subdivision of
the brachial arteries, and on other parts of the
vascular system of the Porpesse, are real additions
to the anatomical history of the Cetacea, by no
means considers it necessary to depreciate the
value of the observations of his predecessors in
the same field of enquiry.

578

The disappearance of the posterior members
has occasioned that of the vessels which should
nourish those members; and as the tail has
attained a considerable development, the arte-
ries and veins which belong to this last part of
the trunk have been developed in the same
proportion. The abdominal aorta does not
send off any external iliacs, but is continued
underneath the tail in the canal of the inferior

rocesses, from whence its ramifications are dis-
tributed to the muscles which move this organ.
The modifications of the venous system are in
many respects analogous to those of the arteries.

Fig. 266.

Ras

Abdominal venous plexus and kidney of the Porpesse.

CETACEA.

The quantity of blood contained in the vascu-
lar system appears to be proportionally much
greater than in the other Mammalia.

A the Porpesse the veins are almost univer-
sally devoid of valves, so that they can be as
easily injected from trunks to branches, as in

the reverse direction. The plexiform disposi-—

tion which we have seen to characterize so
many parts of the arterial system is still more
strongly displayed in the venous. Thus in the
system of the anterior vena cava, with the ex-
ception of the trunk of that vein itself, and the
short jugular veins which join it, an internal
and an external jugular branch, and a pair of
large subcutaneous veins, all the other parts of
the system manifest the plexiform
disposition. This is most remark-
able in the large venous sinuses
surrounding the central axis of the
nervous system, which receives the
intercostal veins, and by means of
which the system of the anterior
cava is chiefly brought into com-
munication with that of the pos-
terior cava; for, as V. Baer has
observed, there is no intercommu-
nicating channel analogous to the
vena azygos of the higher Mam-
malia.

Of the venous plexuses belong-
ing to the system of the inferior
cava, that which is found at the
posterior parietes of the abdominal
cavity extending from below the
kidney to the lower boundary of
the abdomen is the most remark-
able, and we have selected in
illustration of this, the figure from
Baer’s excellent memoir on the vas-
cular system of the Cetacea.* In
this figure (fig. 266) the anterior
parietes of the abdomen are remo-
ved. The twoimmense lateral de-
pressor muscles of the tail are seen
at A, A, and B shows their point
of convergence to be inserted into
the inferior spinous processes, by
which the cavity of the abdomen is
contracted and defined posteriorly.
Just anterior to this commissure
is seen the termination of the rec-
tum H. C,C, are the two ischia.
D, D, the posterior parietes of the
chest projecting forwards over the
abdomen.
kidney and the peritoneum are re-

the oviduct and ovary K,

4

interspace of the two great dep
sors of the tail.
vena cava seems smaller

ke “ g

hys.

* Ueber das Gefass - s
Braunfisches, Nova Acta,

, i .
SS.

OO a ee re

On the right side the
moved; on the left side they are —
seen in situ, and also a part of the —

left cornu of the uterus G, with

At p is seen the inferior vena —
cava cut through, which lies in

The trunk of the

Leopold, Carol. tom. xvii. 1835.

CETACEA.

really is, on account of its deep position and
the overlapping of the kidney, HE. As it gets
beyond this part it is seen to dilate. Two veins,
corresponding to the vene iliace of Quadrupeds,
(m, m,) return the blood in part to the tail, and
join the vena cava near the kidneys. The vein
corresponding to the caudal or sacro-median of
Quadrupeds is not a simple vessel, but a
plexus, which is surrounded and protected by
the inferior spinous processes ; it is seen at f.
A venous plexus from the intestinal canal (g)
terminates in the right iliac vein, which is
larger than the left, and thus establishes a com-
munication between it and the portal system.
A shows a muscular vein, and i the termination
of a hypogastric plexus.

The more important plexuses which commu-
nicate with the iliac veins are, first, the perito-
neal plexus (/), which in older individuals, and
especially at the season of sexual excitement, is
much more considerable than is here repre-
sented; and secondly, the iliac or psoadic
plexus (k,k), which forms an immense reser-
voir of venous blood. It is situated between
the under surface of the depressors of the tail,
which represent the psoas muscles, and the
peritoneum, reaching from behind the lower
extremity of the kidney to the posterior end of
the abdomen, and forming a mass of closely
interwoven veins, of an inch or more in thick-
ness, and serving to bring the subcutaneous
veins of the posterior part of the body into
communication with the posterior vena cava.

This plexus is fed, if we may use the ex-
pression, by a, an inferior vein; ), a lateral ;
and c, a superior vein of the tail, which unite
to form an ischiadic sub-plexus, d. Laterally
the iliac plexus receives from five to seven
veins, which return the blood from the dorsal
and lateral parietes of the abdomen, and pierce
the lateral abdominal muscles to join the plexus
at e,e. On its internal or mesial edge the iliac
plexus communicates by many and wide aper-
tures with the iliac vein. At the anterior part
of the abdomen the inferior cava receives the
plexus phrenicus, 9, o.

The condition of the venous system above

described, while it is admirably adapted to the
mode and sphere of existence of the Cetaceans,
presents a beautiful instance of that co-ordinate
analogy to the condition of the veins in the
embryo of the higher Mammals, which is ex-
hibited in the general form of the animals
composing this the lowest order of the class. |

Orcans or Resprration.—The organs and
all the essential phenomena of respiration are
the same in the Cetaceans as in the other
Mammals. They have been made the subject
of but few observations.

[In the Dugong the lungs are of a very elon-
gated and flattened form, resembling those
which Daubenton has figured of the Manatee.
They are, as Sir Everard Home has observed,
one-fourth the length of the animal; those
from the animal, eight feet long, which he re-
ceived from Sir Stamford Raffles, measuring
two feet. They are convex posteriorly or on
the dorsal aspect, flattened on the opposite
side, and along this surface the principal

579

branches of the bronchi can be seen through
the serous covering. The upper end of each
lung is obtuse, thick, and narrow ; they gradu-
ally become flatter towards the lower extremity,
the margin of which is rounded.

The whole surface of these lungs presents an
appearance somewhat similar to that of the
Turtle ( Chelonia Mydas ), in consequence of
the large size of the superficial air-cells, which
are a line in diameter (a, a, fig. 268.) The
great extent of the lungs down the back, and
the high division of the trachea, and consequent
length of the bronchi, are further instances of
this resemblance.

Fig. 267.

Cartilages of the bronchus of the Dugong.

The cartilages of the bronchial tubes are
continued spirally into one another (fig. 267) :
the pulmonary artery lies to the outer side of
the bronchus and is deeper seated; the pulmo-
nary vein to the inner side, and is superficially
situated. The principal branch of the bron-
chus (6b, fig. 268) runs down near the inner
margin of the lung, and continues distinct to
within four inches of the end; it then divides
into smaller branches; the larger ramifications
are given off from its outer side, c,c. In all
the branches the cartilaginous rings continue
distinct and strong till their diameter is con-
tracted to one or two lines; the rings passing
irregularly into each other as in the main
trunks. The lining membrane of the air-
tubes is thrown into longitudinal ruge, in-
dicating their dilatability. We have before
mentioned the large size of the pulmonary
artery: in this respect, as well as in_ the
structure of the lung, the Dugong manifests
a greater similarity to the reptile than thie
Porpoise does. In this animal the air-cells in
no part of the lung exceed a sixth part of the
size of the superficial ones in the Dugong ; and

580

rai)

|)
Ha A

CETACEA.
Fig. 268.

Structure of the lung of the Dugong.

the pulmonary artery is proportionally smaller.
From the difference that exists in the locomo-
tive habits of the two animals arising from the
difference in the nature of the food, may be
deduced the circumstances which relate to the
difference in the respiratory organ. The Por-
poise, ever bounding and gambolling on the
surface, breathes as it were at will; whilst the
Dugong is compelled to prolonged submersion
in order to acquire its food, which from its
fixed attachment, and comparatively innutri-
tious nature, necessarily demands much time
in collecting. ]

It is said that, in the Dolphins, each lung
is surrounded by muscular fibres, which take
part also in the acts of inspiration and expi-
ration, and that the lobes communicate with
each other in such a manner that, air being
introduced through one of the bronchi alone,
they are all filled with it.

Fig. 269.

Vertical section, shewing the tongue, larynx, and nostrils of the Porpesse.

But though the diaphragm, the lungs, the
bronchi, and the trachea are only found
with modifications of a secondary order, the
nostrils, which serve intermediately for the
passage of the air, between the atmosphere
and the respiratory organ, present very im-
portant ones. It is especially upon these mo-
difications that the exterior distinction between
the Herbivorous and the Spouting Whales de-
pends. In the structure of the nostrils, the
mechanism by which the phenomenon of the
spouting is produced has necessarily caused
some changes, which, on the one hand, appear
to have necessitated the exclusion of the organ
of smell, and, on the other, to have led to the
formation of a new organ entirely peculiar to
this order of Mammalia.

We may be allowed to believe that this
organ is essentially the same in the Dolphins,
the Cachalots, and the Whales; it has only,

i
1
4
1
8
~)
.

CETACRA. | 581

however, been studied with any detail in the
Dolphins, and its principal parts consist in
the larynx, which ascends as far as the pos-
terior nares; in the disposition of the mus-
cles of the pharynx, which have the power
of binding the anterior part of the respiratory
organ; and in the membranous and fleshy bags
placed at the superior part of the nostrils.

The orifice of the spouting hole, which is
simple in the Dolphins, is situated towards
the summit of the head (f, fig. 269); in the
Cachalots it is equally simple, and situated
at the superior extremity of the snout; and in

_ the Whales it is double, and opens towards

the summit of the head, as in the Dolphins,
under the form of a crescent, the convexity of
which is sometimes forward and sometimes
backward.

In the Herbivorous Cetaceans, the orifice of
the nostrils is found, in the Manatee at the
anterior extremity, and in the Dugong at the
middle and upper part of the snout.

[ We here subjoin the detailed description of
the spouting apparatus of the Porpesse, from
the pen of Baron Cuvier. “ If we trace the
esophagus upwards, we find that when it
arrives opposite the pharynx (a, fig. 269), it
appears to divide into two passages, of which
one (b) is continued onwards to the mouth,
while the other (c) mounts to the nose:
this latter passage is surrounded with mucous
glands me fleshy fibres which constitute
several muscles. Some of these are longitu-
dinal, arising from the circumference of the
posterior orifice of the bony nostrils, and de-
scending along that canal to the pharynx and
its lateral parts; the others are annular and
seem to be a continuation of the proper mus-
cle of the pharynx; as the larynx rises into
this posses in the form of an obelisk or py-
ramid, these annular fibres have the power of
grasping it by their contractions.

“ All this part is provided with mucous fol-
licles which pour out their secretion by con-
spicuous excretory orifices. The lining mem-
brane of the nasal passage having reached the
vomer (d), assumes a peculiar texture; it be-
comes thin, smooth, and of a black colour,
is apparently destitute of vessels and nerves,
and is very dry.

“The two osseous nasal canals are closed at
the superior or external orifice by a fleshy
valve in the form of two semicircles, attached
to the anterior margin of that orifice, which it
closes by means of a very strong muscle lodged
above the intermaxillary bones. In order to
open it, some foreign body roust press against it
from below. When this valve is closed, it cuts
off all communication between the nasal pas-
sages and the cavities above them. These ca-
vities are two large membranous pouches (e, e),
formed by a dark-coloured mucous skin, much
wrinkled when they are empty ; but assuming,
when distended, an oval figure, which, in the
Porpesse, equals the capacity of a wine-glass.
These two pouches are lodged beneath the
integument, in front of the nostrils; they
communicate with an intermediate space im-
mediately above the nostrils, which open ex-

ternally by a transverse semilunar slit. Very
strong fleshy fibres form an expansion, which
covers all the upper surface of this apparatus ;
these fibres radiate from the entire circum-
ference of the cranium to unite above the two
pouches, and are adapted to compress them
forcibly. Let us suppose the Cetacean has
taken into its mouth some water which it
wishes to eject : it moves its tongue and jaws as
if it were about to swallow it; but, closing its
pharynx, it forces the water to mount into the
nasal passages, where its progress is accelerated
by annular fibres, until it raises the valve and
distends the membranous pouches above.
Once in the pouches, the water can be re-
tained there until the animal wishes to spout.
For that purpose, it closes the valve to prevent
the descent of the water into the nasal passages,
and it forcibly compresses the pouches by
means of the muscular expansions which cover
them: compelled then to escape by the nar-
row crescentic aperture, it is projected to a
height corresponding to the force of the pres-
sure.”

Urinary organs.—The Phytophagous Ceta-
ceans are not distinguished by a form and
structure of the kidney different from that in
the Zoophagous tribes; for, although in the
Dugong the kidney has an uniform unbroken
external surface, yet in the genus Rytina,
according to Steller, that organ is subdivided
into a great number of Iecbules, as in the Seal
and Sea-Otter, and consequently resembles in
this respect the typical or true Cetacea. Hun-
ter makes the same statement with respect to
the Manatee.*

In the Dugong the tubuli uriniferi terminate
by two lateral series of eleven mammille ina
single elongated pelvis, from which the ureter
is continued. In the Porpesse and Whale
there is no common pelvis, but the ureter com-
mences by more than two hundred branches
from as many distinct lobes or renules, of the
aggregate of which the entire kidney is formed
( E, fig. 266). Each renule is of a conical figure,
having its base towards the circumference, and
its apex towards the centre of the kidney ;
it is composed of a cortical and medullary
substance, the latter terminating in a single
mammilla at the apex, where it is surrounded
by a long infundibulum, wide at its com-
mencement, where it embraces the base of the
mammilla, and thence becoming smaller, and
uniting with others to form the common ex-
cretory duct.

Muller found that each of the lobules of
the kidney in the fetus of the Dolphin con-
sisted principally of the convoluted uriniferous
ducts extending from the apex to the periphery
of the lobule, the intertwinings of the tubuli
being greatest in the cortical part (fig. 270).

It is acurious fact that the supra-renal gland
in the Porpesse presents a certain resemblance
to the kidney in its lobulated exterior; but the
analogy extends no farther, for on making a

‘section of this part, it is seen to be composed

of the usual continuous compact substance. }

* In the paper on Whales, p. 412.

582 CETACEA.

To judge from the capaciousness of the
skull, the other species of this family of Cetacea
have not been less liberally gifted than the
common Dolphin. The brain of the Cachalots
and the Whales has not been made a subject
of study, or has been so only in a very super-
ficial way. To judge of it by the cranial —
cavity, one may conclude that in them this
organ is reduced to very small dimensions.

[The illustrations of the brain of the Cetacea |
(fig. 271, 272, 273) are taken from the ex-
cellent figures of the brain of the Dolphin 4
( Delphinus Delphis_), published by Tiedemann .
in the second volume of his Zevtschrift fur |
Physiologie, (pl. xii. p. 251.) The- following
description embodies the observations of the

The Nervous System.—The nervous systeM, same author on the brain of the Dolphin, and
like the greater part of the other organic sys- of Hunter on that of the Balenoptera (Piked
tems, has in many species of the Cetacea been Whale). In a young specimen of the Balena
the subject only of superficial observations. rostrata, which measured seventeen feet, Hunter
Formed on the plan of that of Mammalia in }
general, it has followed in its deve- Fig. 272.
lopment that of the other organs, in <EN]
all cases in which it was naturally de-
pendent on such modifications. ‘Thus
the lumbar and sacral nerves do not
give origin to those of abdominal
members, whilst, on the other hand,
the coccygeal nerves are found nume-
rous and powerful. The olfactory 7
nerves do not exist, unless, as some f/
authors say, it is in the form of almost |
imperceptible threads. What appears |i!
certain is, that in the common Dol- \\\\
phin, and in the common Porpesse
there are no traces of ethmoidal
openings; and if there are holes in
the ethmoid of the Whale, they are
in very small number, and nothing
proves that they give passage to

A section of one of the lobes or renules of the kidney
of a Dolphin.

™,. ARS
nerves.* In the common Dolphin mee WE _sfWF KR. lip
and Porpesse, the brain is found as fiz “itis
richly developed as in any Mammi-
ferous quadruped whatever.

Base of the brain of a Dolphin, Delphinus Delphis.

( found that the brain weighed four .
Fig. 271. pounds eight ounces. In a young
Sa), ee Balena mysticetus nineteen feet 7
long, Scoresby found the weight of i
the brain to be three pounds twelve ‘
ounces. From analogy we may
suppose that the brain had here
acquired nearly its full development,
which gives us, taking the weight
of the full grown whale at 11,200
pounds, the ratio of the weight of
the brain to that of the body as
somo: In the smaller Cetacea,
however, the brain is not dimi- —
nished to a proportionate size, but —
exhibits a development which may —
be said to be extraordinary, even ©
in the Dolphin of six feet in
length. /|
~ In tracing the brain according to
= / Tiedemann’s method from beloy

Brain of the Dolphin, Delphinus Delphis. upwards, we first observe th

* M. F. Cuvier seems here to have overlooked the ‘ In many of this (the Whale) tribe, there is no
fact that Hunter had established the existence of organ of smell at all; and in those which have
an organ of smell in the Balenide. He observes, such anorgan, it is not that of a Fish, theref

CETACEA.

spinal chord (a, fig. 272) gently expanding
| into the medulla oblongata, on the anterior
3 surface of which the corpora pyramidalia (b,
fig. 272) are seen well defined and prominent.
| At the point where they begin to rise above
the surface of the medulla, there is a manifest
decussation of their internal fibres; they pro-
: ceed through the pons Varoli (c), and are
; continued into the crura cerebri.

The a olivaria are situated near the
pieotiieha : they do not, however, project
from the surface as in the human brain, but
are distinguishable by the internal grey sub-
stance (corpus dentatum olive). Their medul-
lary fibres proceed through the pons and enter
the bigeminal bodies, in which they converge
and decussate each other.

The transverse medullary fibres, which are
seen in most Mammalia extending across the
under surface of the medulla oblongata imme-
diately behind the pons, and which Treviranus
has called the trapezium, are wanting in the
brain of the Dolphin, as in that of the Orang
Utan and the Human subject.

The two posterior columns of the spinal
chord are continued (according to Tiedemann)
as the corpora restiformia to the cerebellum.
Between these is situated the fourth ventricle,
from the floor of which the acoustic nerves
take their origin.

The very large size of the cerebellum in
proportion to the spinal chord and cerebrum,
which Hunter noticed in the Piked Whale, is
equally remarkable in the Dolphin. The cere-
bellum is deeply divided into lobes, of which
_ six may be distinguished on the upper surface
_ ofeach hemisphere. Of these, two small lobes
_ correspond to the posterior superior lobes of

the human cerebellum.

On the under surface we remark
the posterior inferior lobes (e), the
anterior inferior lobes (7), one lobe
corresponding to the amygdaloid
lobe of Reil (g), and the floccus

h). Each lobe is subdivided by

eep fissures into smaller lobes, and

these again by shallow anfractu-
_ sities into lamelle. The middle
_ or vermiform portion of the cere-
bellum (a, fig. 273) is not sym-
metrical, but inclined, like the cra-
nium itself, to the right side. The
internal medullary substance of the
cerebeilum resulting from the di-
vergent fibres of the crus, corpus
restiforme, and processus ad testes,
and the superadded commissural
fibres, has a well-marked internal
grey substance or corpus fimbri-

Py
:

;

iY

ly not calculated to smell water. It becomes
lt therefore to account for the manner in
_ which such animals smell the water ; and why the
poets should not have had such an organ, which
q to be peculiar to the large and small Whale-
> a bone Whales ( Balena mysticetus and B tera
rostrata ); the organ, in those which have it, is ex-
_ tremely small, when compared with that of other
; "animals » as well as the nerve, which is to receive

_ the impression.”—Phil. Trans. pp. 428, 430.

_

a)

en
x mt Nl a c
|

=

583

atum, and is covered by the usual external
layer of similar material. Between the columns
which extend from the cerebellum to the bige-
minal bodies, the medullary lamella called
valvula Vieussenii is situated. The pons or
commissure of the cerebellum (c, fig. 272) is of
large size, corresponding to the hemispheres of
the part which it seems to associate in action.

_ The cerebrum is extended backwards over
the cerebellum, but the posterior parts of the
hemispheres diverge from one another so as to
expose a part of the cerebellum. The most
striking feature of the cerebrum is its great
breadth, which exceeds its length, a disposition
of this organ peculiar among Mammalia to
the Cetaceous order. Each hemisphere is seen
at its inferior surface to be divided by the
Jissura magna (k, fig. 272) into an anterior
(2) and middle lobe (m), which latter is con-
tinued above the cerebellum into the posterior
lobe. The whole external surface of the he-
mispheres is divided by deep anfractuosities
into convolutions, which are proportionally
more numerous and narrower even than in the
human brain. This structure seems common
to all the Cetacea; besides the observations of
Tiedemann and Cuvier in the common Dol-
phin, the numerous convolutions have been
remarked by Tyson in the brain of the Por-
pesse, and by Scoresby in that of the Mysticete
Whale.

The crura cerebri (i, fig. 272) are of large size;
the eminentie mammillares (p) are as usual
situated between them, and anterior to these
are the infundibulum and pituitary gland (0).

The two hemispheres in the Dolphin’s brain
described by Tiedemann, measured each two
inches and eleven and a half lines in length,
and were united by a corpus callosum (6, fig.

Ma |

i

. .

‘)

}

| i
% )

! Hn
.
y

273,) of one inch and three lines in length. The
chief peculiarity of this part is its position,
which is not horizontal, but inclined down-
wards and forwards. The bigeminal bodies
are of considerable size ; the anterior ones are
rounded and lie closer together than the pos-
terior. These have an oval form, and are
separated by a depression which receives the

584

anterior part of the vermiform process of the
cerebellum.

The pineal gland is a small flattened body
about two lines in length, connected as usual
to the thalami optict. These appear in each
ventricle in the form of an oval flattened
body (7, fig. 273). They are joined together
posteriorly by the medullary commissure.
Tiedemann did not observe any soft commis-
sure. .

The third: ventricle is continued anteriorly
into the infundibulum.

The corpora striata (d) are proportionally of
small size, as Hunter observed in the brain
of the Whale. They are united anteriorly by
the anterior commissure.

The fornix is also of inconsiderable size.
The slender anterior pillars of the fornix proceed
to the mammillary bodies, and send forwards
two small triangular medullary lamelle to the
under surface of the anterior part of the corpus
striatum, from which the septum lucidum is
continued. The fornix then bends backwards
along the under surface of the corpus callosum
and above the thalami, and its hinder crura
sink down, diverging from each other to form
the cornua ammonis (g). These bodies are
small, thin, but broad, and exhibited no den-
ticulated folds. The tenia fimbriata (A) are
attached as usual to the external border of the
cornua.

The lateral ventricles are capacious though
short; they extend, as in the human brain,
into an anterior, a middle, and a posterior horn ;
the latter, however, is very small. In each
ventricle there is a large plexus choroides, which
is remarkable for the transverse parallel folds
of membrane which support the divisions of
the artery.

With respect to the cerebral nerves, Tiede-
mann states that, although in the Dolphin the
brain was removed with every precaution from
the skull, yet he could not perceive the slightest
trace of the olfactory pair. Hunter and Tyson
equally failed to detect them in the Porpesse.
Treviranus, however, believed that with the
aid of a magnifying glass he had detected very
delicate filaments in the situation of the olfac-
tory nerves in the Porpesse. But supposing
that there was no illusion here, which could
hardly have happened to so accurate and close
an observer, these fibres represent only a very
rudimental condition of the olfactory nerves ;
and we may observe that the shortness of the
anterior lobes of the brain, and the smallness
of the striated bodies are closely related to the
absence or imperfect development of the first
pair of nerves.

With respect to the other cerebral nerves,
they are relatively larger in proportion to the
brain than in man. The optic nerves (2, fig.
272) rise partly from the thalami, partly from
the anterior bigeminal bodies and the corpora
geniculata; they curve round the crura cerebri,
and unite as usual before the pituitary gland.
The angle at which the nerves diverge from
each other after the decussation is more open
than in other Mammalia.

The accessory nerves of the eye are of large

CETACEA.

size, as the third (3), the fourth (4), and the
sixth (6) pair. 4h Ss sgl

The fifth pair (5), which emerge from the
sides of the pons, but arise from the medulla
oblongata between the corpora restiformia and
olivaria, have a smaller proportional size than —
in man. |

The nerves concerned in the actions of
respiration, as the facial (7), the pneumogastric. —
(10), and the recurrent (11), are well deve-
loped, in relation to the large size of the
muscles which effect the respiratory movements
in the dense medium of water.

The glosso-pharyngeal nerve (9) and the
lingual (12) are also very large, corresponding
to the vigorous associated actions of the tongue
and pharynx, which must take place during
deglutition in the Cetacea.

But perhaps the most remarkable nerve for
its great relative size is the acoustic (8), which
certainly testifies to the delicate sense of hear-
ing in the Dolphins. |

The organs of the senses, with the exception
of that of smell, are composed, in all the
Cetaceans, of the parts which essentially con-
stitute them in terrestrial Mammalia, and are
only modified with reference to the habitually
aquatic life of the animals of this order. But
little inquiry has been made as to their utility
in these animals, the length of time they con-
tinue serviceable, and the characteristic diffe-
rences which might be drawn from them for
the distinction of the species.

Eye.—The eye of the Herbivorous Cetaceans
alone is provided with a lateral lid or membrana
nictitans ; that of the Spouting Whales is de-
void of lachrymal glands; but its lids are fur-
nished below with little glands which secrete a
mucous matter, adapted like the tears for
lubricating the sclerotica.

Hunter observes that “the eye in this
tribe of animals is constructed upon nearly
the same principle as that of quadrupeds, dif-
fering, however, in some circumstances; by
which it is probably better adapted to see in
the medium through which the light is to pass.
It is upon the whole small for the size of the
animal, which would lead to the supposition
that their locomotion is not great; for, I believe,
animals that swim are in this respect similar to
those that fly; and as this tribe come tothe
surface of the medium in which they live, they __
may be considered in the same view with birds
which soar; and we find, birds that fly to
great heights, and move through a considerable _
Space, in search of food, have their eyes larger
in proportion to their size. vd

“ The eyelids have but little motion, and —
do not consist of loose cellular membrane, as —
in quadrupeds, but rather of the commoi nn
adipose membrane of the body ; the connexion, ~
however, of their circumference with the com-
mon integuments is loose, the cellular mem-
brane being less loaded with oil, which allow
of a slight fold being made upon the sui
rounding parts in opening the eyelids. Th
is not to an equal degree in them all, bein
less so in the Porpoise than in the Pike
Whale. a

CETACEA. 585

Section of the eye of a Whale.

“ The tunica conjunctiva (g, g, fig. 274),
where it is reflected from the eyelid to the eye-
ball, is perforated all round by small orifices
of the ducts of a circle of glandular bodies
lying behind it.

“ The lachrymal gland* is small, its use
being supplied by those above-mentioned ; and
the secretion from them all, I believe to be
a mucus similar to what is found in the Turtle
and Crocodile. There are neither puncta nor
lachrymal duct (ductus ad nasum), so that the
secretion, whatever it be, is washed off into
the water.

“The muscles which open the eyelids are
very strong; they take their origin from the
head, round the optic nerve, which in some
requires their being very long, and are so
broad as almost to make one circular muscle
_ found the whole of the interior straight mus-
_ les of the eye itself. They may be divided

_ into four; a superior, an inferior, and one at

each angle; as they pass outwards to the eye-
lids, they diverge and become broader, and are
inserted into the inside of the eyelids almost
equally allround. They may be termed the
dilatores of the eyelids; and, before they
reach their insertion, give off the external
straight muscles, which are small, and inserted
into the sclerotic coat before the transverse axis
of the eye; these may be named the elevator,
depressor, adductor, and abductor, and may
be dissected away from the others as distinct
muscles. Besides these four going from the
muscles of the eyelid to the eye itself, there are
two which are larger, and enclose the optic
_ herve with the plexus. As these pass outwards
they become broad, may in some be divided
into four, and are inserted into the sclerotic
coat, almost all round the eye, rather behind
its transverse axis.
___ “ The two oblique muscles are very Iong ;
_ they pass through the muscles of the eyelids,
_ are continued on to the globe of the eye,
the two sets of straight muscles, and
at their insertions are very broad: a circum-

_* This is analogous rather to the Harderian
» being situated at the inner or nasal side of
eyeball.
VOL, I.

stance which gives great variation to the motion
of the eye.

“ The sclerotic coat (a, a, fig. 274) gives
shape to the eye, both externally and internally,
as in otheranimals; but the external shape and
that of the internal cavity are very dissimilar,
arising from the great difference in the thick-
ness of this coat in different parts. The external
figure is round, except that it is a little flat-
tened forwards; but that of the cavity is far
otherwise, being made up of sections of
various circles, being a little lengthened from
the inner side to the outer, a transverse section
making a short ellipsis.

** In the Piked Whale ( Balenoptera ros-
trata) the long axis is two inches and three
quarters, the short axis two inches and one-
eighth.

“‘ The posterior part of the cavity is a
tolerably regular curve, answering to the dif-
ference in the two axises; but forwards, near
the cornea, the sclerotic coat turns quickly in,
to meet the cornea, which makes this part of
the cavity extremely flat, and renders the
distance between the anterior part of the scle-
rotic coat and the bottom of the eye not above
an inch and a quarter.

“ In the Piked Whale the sclerotic coat, at
its posterior part, is very thick: near the ex-
treme of the short axis it was half an inch,
and at the long axis one-eight of an inch thick.
In the Bottle-nose Whale ( Hyperoodon ), the
extreme of the short axis was half an inch
thick, and the extremes of the long axis about
a quarter of an inch, or half the other.

“ The sclerotic coat becomes thinner as it
approaches to its union with the cornea, where
it is thin and soft. It is extremely firm in its
texture where thick, and from a transverse sec-
tion would seem to be composed of tendinous
fibres, intermixed with something like carti-
lage; in this section four passages for vessels
remain open. This firmness of texture pre-
cludes all effect of the straight muscles on the
globe of the eye by altering its shape, and
adapting its focus to different distances of
objects, as has been supposed to be the case in
the human eye.

“ The cornea (b, fig. 274) makes rather a
longer ellipsis than the ball of the eye; the side
of which are not equally curved, the pp
being most considerably so. It is a segmen.
of a circle somewhat smaller than that of the
eyeball, is soft and very flaccid.*

“ The tunica choroides resembles that of the
quadruped ; and its inner surface is of a silver
hue, without any nigrum pigmentum. The
pigmentum nigrum only covers the ciliary
eee (c, c), and lines the inside of the iris.

e retina (e) appears to be nearly similar to
that of the quadruped.

“« The arteries going to the coats of the eye
form a plexus passing round the optic nerve,
resembling in its appearance that of the sper-
matic artery in the Bull and some other ani-
mals.

* Its laminated texture is well displayed in the
Whale ; Leeuwenhoek counted twenty-two layers.
2 Q

586

« The crystalline humour (d) resembles that of
the quadruped ; but whether it is very convex
or flattened, I cannot determine; those I have
examined having been kept too long to pre-
serve their exact shape and size. The vitreous
humour adheres to the retina at the entrance
of the optic nerve. The optic nerve (/') is it
long in some species, owing to the vast widt
of the head.’*

The crystalline lens is of a spherical form,
but slightly flattened anteriorly : it is inclosed
in a strong and dense capsule, and is placed
at a very small distance from the cornea, so
that it diminishes the space for the aqueous
humour, while it increases that for the vitreous;
this exists in a greater degree than is shown in
the subjoined figure, as Soemmering, from
whose work * De oculorum sectione horizon-
tali’ the figure is taken, himself allows. From
the peculiar colour and eccentrie position of
the nucleus of the lens in the Whale’s eye, in
which it is of a dark colour, and placed in the
posterior half of the lens, we are led to suspect
that the section of the lens in Soemmering’s
plate is imaginary. |

Ear.—The ear is without any external con-
cha; no doubt a sphincter has the office of
closing the entrance of the auditory canal, to
preserve the tympanum, which some call fi-
brous, and others cartilaginous, from the
contact of the water. The Eustachian tube
exists according to some anatomists, others
deny it. The senses of sight and hearing, not-
withstanding their apparent imperfection, appear
to be endued with great delicacy. Whale-
catchers assert that Whales, Cachalots, &c. see
and hear at a great distance, and that, in order
to approach them, many precautions are neces-
sary; otherwise these animals would avoid
them bya sudden retreat, and it would become
necessary to recommence the long and labo-
rious chase. We ought, nevertheless, to add
that Scoresby, who speaks of the delicacy
of hearing of the Whales, states that they
remain insensible to the noise of the report of
a cannon.

[For the most accurate and philosophical
description of the Organ of Hearing in the
present tribe we again recur to Hunter’s ad-
mirable paper on the organization of the
Cetacea. He observes, that “ the ear is con-
structed much upon the same principle as
in the quadruped ; but as it differs in several
respects, which it is necessary to particularize,
to convey a perfect idea of it the whole should
be described. As this would exceed the limits
of this paper, I shall content myself with a
general description, taking notice of those ma-
terial points in which it differs from that of the
quadruped.

‘¢ This organ consists of the same parts as in
the quadruped ; an external opening, with a
membrana tympani, and Eustachian tube, a
tympanum with its processes, and the small
bones.

“‘ There is no external projection forming a
funnel, but merely an external opening. We

* Philos. Trans. 1787, p. 440,

CETACEA.

can easily assign a reason why there should be
no projecting ear, as it would interfere with
progressive motion; but the reason why it is
not formed as in birds, is not so evident; whe-
ther the percussions of water could be collected
into one point as air, I cannot say. The tym-
panum is constructed with irregularities, so
much like those of an external ear, that I could
suppose it to have a similar effect.

“ The external opening begins byasmall hole,
(a, fig. 275), scarcely perceptible, situated on

Fig. 275.

Organ of Hearing, Porpesse.

the side of the head a little behind the eye. It
is much longer than in other animals, in con-
sequence of the size of the head being so much
increased beyoud the cavity that contains the
brain, It passes in a serpentine course (6), at
first horizontally, then downwards, and afterwards
horizontally again, to the membrana tympani,
where it terminates. In its whole length it is
composed of different cartilages, which are irre-
gular and united together by cellular mem-
brane, so as to admit of motion, and probably —
of lengthening or shortening, as the animal is
more or less fat.
*« The bony part of the organ (c, c) is not so-
much inclosed in the bones of the skull as inthe —
quadruped, consisting commonly of a distinct —
bone or bones, closely attached to the sku
but in general readily to be separated from
yet in some it sends off, from the posteric
part, processes which unite with the skull. It_
varies in its shape, and is composed of the im-_

_ That

CETACEA.

mediate organ (or labyrinth) and the tym-
um.

“ The immediate organ is, in point of situa-
tion to.that of the tympanum, superior and in-
ternal, as in the quadruped. The tympanum
is open at the anterior end, where the Eusta-
chian tube begins.

“ The Eustachian tube opens on the outside
of the upper of the fauces: in some higher
in the nose than others ; highest, I believe, in

. the Porpoise. From the cavity of the tym-

pone where it is rather largest, it passes
rwards and inwards, and near its termination

a nea very much fasciculated, as if glan-
re ar. (A probe passes through the Eusta-

chian tube in the figure, showing its nasal ter- |

mination at d.)

“ The Eustachian tube and tympanum com-
municate with several sinuses, which passing
in various directions surround the bone of the
ear. Some of these are cellular, similar to the
cells of the mastoid process in the human sub-
ject, although not bony. There is a portion of
this cellular structure of a particular kind, being
white, ligamentous, and each part rather round-
ed than having flat sides.*

“ One of the sinuses passing out of the tympa-
num close to the membrana tympani, .goes a
little way in the same direction, and ‘commu-

| - nicates with a number of cells.

©The whole function of the Eustachian

_ tube is perhaps not known ; but it is evidently
a duct Boos

du the cavity of the ear, or a passage
for the mucus of these parts; the external
ing having a particular form would incline

us to believe, that something was conveyed to

.

_ the tympanum.
“The bony part of the organ is very hard

and brittle, rendering it even difficult to be cut
with a saw, without its chipping into pieces.
part which contains the immediate organ
is by much the hardest, and has a very small
portion of animal substance in it; for when
Steeped in an acid, what remains is very soft,
almost like a jelly, and laminated. The bone
is not only harder in its substance, but there is
on the whole more solid bone than in the cor-
Seeing parts of quadrupeds, it being thick
massy.
_ “The part containing the tympanum is a
thin bone, coiled upon itself, attached by one
end to the portion which contains the organ ;
and this attachment in some is by close contact
only, as in the Narwhale; in others, the bones
run into one another, as in the Bottle-nose and
Piked Whales ( Hyperoodon and Balenop-

_ tera)

“The concave side of the tympanum is
turned towards the organ, its two edges being
close to it; the outer is irregular, and in many

_ only in contact, as in the Porpoise: while in

others the union is by bony continuity, as in
the Bottle-nose Whale ( Hyperoodon ), leaving

_@ passage on which the membrana tympani is

* «<< These communications with the Eustachian
tube may be compared to a large bag on the bases
of the skull of the Horse and Ass, which is a lateral
Swell of the membranous part of the tube, and when

_ distended will contain nearly a quart.”

587

stretched, and another opening, which is the
communication with the sinuses.

** The surface of the bone containing the im-
mediate organ (the petrous bone, p, fig. 269)
opposite to the mouth of the tympanum is very
irregular, having a number of eminences and
cavities.”

According to the Baron Cuvier* the petrous
bone in the Delphinide is permanently lodged
between the temporal and contiguous parts of
the occipital bone; it forms the upper and
inner part ; the tympanum the lower and outer.
The petrous bone is brittle and very thick. It
has a larger portion, an irregular ellipsoid,
which gives attachment to the tympanum by
its outer surface, and which contains the three
semicircular canals; and another smaller por-
tion in the form of a quarter of a sphere, which
is separated from the first by a pretty deep de-
pression, and is occupied internally by the
cochlea. The acoustic nerves enter by fora-
mina at the bottom of the depression.

The tympanum is formed by a thick bony
plate folded longitudinally, so as to form a
canal, open anteriorly, whence is continued the
Eustachian tube. It is closed behind, where
it assumes a bilobate figure, and adheres above
this part to the outer and posterior part of the
petrous bone by a rough process, which is
firmly wedged in, but does not anchylose soon.
It adheres to it also by a part of the external
margin, and it is between these two points of
adhesion that we find the very irregular opening
of the tympanum. The internal margin leaves
a long interval between it and the petrous bone.
Beneath the bilobate portion of the tympanum
the styloid process passes, which is attached
immediately behind it by ligaments to the de-
scending plate, which represents the mastoid
process.

The bone of the ear of the Cachalot displays
great relations with that of the Dolphins,
only the tympanum is shorter and less lobated
behind.

The bone of the ear in the Bulenide differs
from that of the Delphinide by the enormous
thickness of the tympanum (a, fig. 276), espe-
cially at the inner side. This tympanum isa
little more closed anteriorly, but leaves between
it and the os petrosum (b) on the inner side a
proportionally shorter and wider interspace.
It is not bilobed posteriorly. __

The petrous bone is of a very irregular shape
and knotty surface ; it gives off two large rough
processes, of which one is situated behind and
a little above, and articulates with a corre-
sponding process of the tympanum, is wedged
between the temporal and lateral occipital
bones; and the other, situated anteriorly and
below, is articulated by a squamous suture
with the part of the temporal which descends
to furnish the articulation of the lower jaw.
This second process, which in the Bulene 1s as
large as the other, is very small in the Bale-
noptera ; nevertheless the ear-bone of the Ba-
lene is fixed more solidly to the cranium than
that of the Delphini.

* Oss. Foss. vol. v. pt. i. p- 300.
2Q2

5838

A comparison of the ear-bone of Balena
Australis with that of Balena Mysticetus cor-
roborates by differences, slight indeed, the dis-
tinction of species between them.

“The cavity of the tympanum (a, a, fig.
276) is lined with a membrane, which also
covers the small bones with their muscles, and
appears to have a thin cuticle. This membrane

_ renders the bones, museles, tendons, &e. v
obscure, which are seen distinetly when that is
removed. It appears to be a continuation of
the periosteum, and the only uniting substance
between the small bones. Besides the general
lining, there is a plexus of vessels, which is
thin and rather broad, and attached by one
edge, the rest being loose in the cavity of the
tympanum, somewhat like the plexus choroides
in the ventricles of the brain. The cavity, we
may suppose, intended to increase sound, pro-
bably by the vibration of the bone; and from
its particular formation we can easily conceive
that the vibrations are conducted, or reflected,
towards the immediate organ, it being in some
degree a substitute for the external ear.

“ The external opening being smaller than in
any animals of the same size, the membrana
tympani is nearly in the same proportion. In
the Bottle-nose Whale, the Grampus, and Por-
poise, it is smooth and concave externally ; but
of a particular construction on the inner sur-
face; for a tendinous process passes from it to-
wards the malleus, converging as it proceeds
from the membrane, and becoming thinner till
its insertion into that bone. I could not dis-
cover whether it had any muscular fibres which
eould affect the action of the malleus. In the
Piked Whale, the termination of the external
Opening, instead of being smooth and concave,
is projecting, and returns back into the meatus
for above an inch in length, is firm in texture,
with thick coats, is hollow on its inside, and
its mouth communicating with the tympanum ;
one side being fixed to the malleus, by a part
similar to the tendinous process which goes
from the inside of the membrana tympani in
the others.”*

In the figure (fig.276), which represents the
internal ear in the Balena Mysticetus, the let-
ters c, d, e indicate the extent of the membrana
tympani, the letter e being placed on the part
which forms a convex projection into the tym-
panic passage : f shows the triangular ligamen-
tous process which attaches the handle of the
malleus (g) to the membrana tympani. This
connection between the membrane and the
ossicles of the tympanum is denied by Sir
Everard Home, who wrote a paper and pub-
lished two plates in support of his opinion.+
After quoting Mr. Hunter’s description of the
attachments of the membrana tympani in the
Piked Whale, Sir Everard observes, “ the fact
is, that there is no connexion whatever between
the membrana tympani and the malleus, as
will be explained; but as that circumstance
forms the great peculiarity in the organ of this
species of Whale (Balena mysticetus, L.)

* Hunter in Philos. Trans. 1787, p. 432.
+ Philos. Trans, 1812, p. 88, pls. I. and IT,

CETACEA.

Internal ear of the Mysticete Whale.

I thought it right to quote what he had stated
on this subject.” So remarkable an anomaly
as an absence of any communication between
the membrana tympani and the ossicula audi-
tus, would of itself, independently of our inte-
rest for the character of Hunter as an accurate
observer, have induced us to spare no pains to
test the conflicting statements with the facts
themselves ; fortunately in this instance the
preparations figured by Sir Everard are pre-
served ; we have carefully examined them, and
find the following to be the true structure of —
the parts in question. The membrane marked
c in Sir Everard Home’s second figure is con-
tinuous at d, with e the convex projection of
the membrana tympani; whereas the edge of
the shadow is so strong in the figure as to
make it appear as if c and e were separate
membranes, as indeed Sir Everard de- —
scribes them to be: they are, on the contrary,
parts of the same membrana tympani, the at-
tachment of which is extended inwards beyond
the circumference of the termination of the
bony meatus auditorius. The triangular liga-
ment /,; which is common to all the Cetacea, is
attached not only to the plane portion of the
ear-drum, but to the whole of one side of the
convex portion which projects into the meatus, —
and is affected by every motion of that part.
It is a thick opaque aponeurosis, and not, as it
is represented in the plate, a semitransparent
membrane passing clear over the convex part of
the drum. ae
“ A little way within the membrana tym
pani, are placed the small bones, which are
three in number, as in the quadruped, mal-
leus (g), incus (h), and stapes (7); but -
the Bottle-nose Whale (Hyperoodon) there is
fourth, placed on the tendon of the staped
muscle. These bones are as it were suspend
between the bone of the tympanum, and t
of the immediate organ. ial
“« The malleus has two attachments, besi
that with the incus; one close to the bone <

CETACEA.

the tympanum, which, in the Porpoise, is
only by contact, but in others by a bony
union; the other attachment is formed by the
tendon, above described, being united to the
inner surface of the membrana tympani. Its
base articulates with the incus.

“ The incus is attached by a small process to
the tympanum, and is suspended between the
malleus and stapes. The process by which it
articulates with the stapes is bent towards that
bone.

“« The stapes stands on the vestibulum, by a
broad oval base. In many of this tribe, the
opening from side to side of the stapes is so
small as hardly to give the idea of a stirrup.

“The muscles which move these bones are
two in number, and tolerably strong. One
arises from that projecting part of the tym-
panum which goes to form the Eustachian
tube, and running backwards is inserted into a
small depression on the anterior part of the
malleus. The use of this muscle seems to be
to tighten the membrana tympani ; but in those
which have the malleus anchylosed with the
oe aa aay we can hardly conjecture its use.

‘he other (0) has its origin from the inner surface

of the tympanum, and passing backwards is
inserted into the stapes by a tendon, in which
I found a bone in the large Bottle-nose. This
muscle gives the stapes a lateral motion. What
particular use in hearing may be produced by
the action of these muscles I will not pretend
to say ; but we must suppose whatever motion
as given to the bones must terminate in the
movement of the stapes.
_ “ Theimmediate organ of hearing is contained
in around bony process, and consists of the
eochlea and semicircular canals, which some-
what resemble the quadruped ; but besides the
two spiral turns of the cochlea, there is a third,
which makes a ridge within that continued
from the forarnen rotundum and follows the
‘turns of the canal.

“ The cochlea (k, fig. 276) is much larger

when compared with the semicircular canals,
than in the human species and quadruped.”
_ Besides its greater relative size, the coch-
tea of the Delphinide differs from that of
the human subject in the greater pro-
portional extent, and especially the form and
disposition of the scala vestibuli, which, in-
stead of being one compartment of a single
tube divided in the direction of its axis, is a
complete conical tube. It also forms an oblique
sigmoid curve before commencing its spiral
turns, which are two and a half in number.

The semicircular canals have the same dis-
position as in Mammalia, but are relatively
smaller.

Cuvier, in correcting the error into which
Camper had fallen when he denied the
_ existence of the semicircular canals in the
_ Whale, appears to have overlooked the fact
_ that they had previously been discovered in

the Cetacea by Hunter. And it is simply be-

_ fause they do not possess any difference of

_ note as compared with other Mammalia, (ex-
_ cept in their relative volume to other parts of
_ #he labyrinth which Hunter is careful to point

589

out,) that they are not described by him with
the same minuteness and detail as the cochlea
and other parts of the organ. It may also be,
observed that the more extensive researches of
Hunter preserved him from the error into which
Cuvier has fallen of ascribing to the Cetacea a
structure of the cochlea which is peculiar to a
small part only of the order. The depression
of the gyrations of the cochlea to nearly the
same plane, and their limitation to one and a
half in number, is certainly not applicable to
the Delphinide, and it may be doubted how
far it can be with accuracy asserted of the
Balene.*

The canals which establish a communication
between the labyrinth and the interior of the
cranium, viz. the aqueductus vestibuli and
aqueductus cochlex, are very large in the Del-
phinide, especially the latter. |

Taste-—This sense probably exists in the
Herbivorous Cetaceans, whose tongue, although
but slightly moveable, has notwithstanding a
complicated and delicate structure. But has
this sense a special organ in the Spouting Ce-
taceans? Some doubts may be allowed to
exist on this subject. 'The tongue of the Dol-
phin and that of the Porpoise have neither
fossulate papille nor conical papille ; they only
present on their surface slight elevations, of
which the middle appears to be perforated, and
their edges are fringed, as if for multiplying
the sensations of touch.

‘ouch—The general organ of touch, the
skin, has formed, in the Spouting Cetaceans,
the subject of impertant researches, which have
given a more extended knowledge of this organ
in general than was before possessed.

According to the observations of MM.
Breschet and Roussel de Vauzéme, there may
be distinguished in the skin of the Cetaceans,
as in that of other Mammals, six principal
constituents which either penetrate or are
superimposed on ohe another, but which are
severally destined to fulfil a special function.

1. The derm or corium (le derme), a dense
fibrous cellular texture, which contains and
protects all the other parts of the skin. In
the Whale it is constantly white and opake,
and its peripheral surface presents a series of
papille, the intervals of which are occupied
by the epidermis, which forms for each a
sheath.

2. The papillary bodies (des corps papil-
laires) consist of papillae covered by the derm.
They have a nacrous lustre, and are several
lines in length in the Whale, but are much
shorter in the common Dolphin and Porpesse.
These papille are composed of fibres pene-
trated by vessels; they originate from the sub-
cutaneous nervous plexus and return back again
to the same; the derm serves merely as a
sheath to the papille, the extremities of which
exercise the sense of touch.

3. The sudorific apparatus (l’appareil sudo-
rifique,) consists of soft, elastic, spiral canals,
which extend through the entire thickness of

* See Ossem. Foss. vol. v. pt. i. p- 300, and
Lecons d’Anat. Comparée, vol. ii. p. 467.

590

the derm, and open in the intervals of the
papille by an orifice generally closed by a
small epidermic valve.

4. The inhalent apparatus (l’appareil d’in-
halation) is formed by extremely delicate
canals, which are smooth, straight, silvery,
branched, and very easily ruptured: they
originate in a plexus extended in the dermis
beneath the sudorific canals, anastomose to-
gether, and are provided with partitions. The
lymphatic vessels have no connection with
these canals, which communicate directly with
the arteries and veins. They are absorbing
canals.

5. The mucous apparatus (l'appareil blen-
nogene). This is composed. of secerning
glands and excretory ducts, which open be-
tween the papille like the orifices of the pre-
ceding canals. It is wholly contained in the
derm, and produces a mucous material, which
by desiccation (en se dessechant ) becomes the
cuticle. In the Whales this cuticle acquires
an extreme thickness: it is much thinner in
the Dolphins.

6. The colorific apparatus (l'appareil chro-
matogéne ) is likewise composed of secerning
glands and excretory ducts; it is situated in
the first superior (peripheral) layers of the
corium on the right and left sides of the outlet
of the excretory ducts of the preceding appa-
ratus, and it pours out the coloured product
at the same point where the mucous matter is
excreted, where it stains it.

[It may be questioned how far this expla-
nation satisfactorily accounts for the formation of
cuticle in animals living habitually under water,
The whole account is to be received with reserve,
and requires to be confirmed by further ob-
servations, especially as regards the reflexion
of the nervous fibrils and the sudorific and
inhalent apparatuses. |

We do not stop to examine how far this
analysis serves to explain the different phe-
nomena which the external teguments of the
Mammalia present. But admitting it as it is
presented to us, it results that the sensations
of touch must be lively and delicate in the
Cetacea: the great development of their pa-
pillary apparatus leads to this conclusion.
Nevertheless, the most generally received opi-
nion is that the common Dolphin, notwith-
standing the delicacy of its epidermis, has but
little tactile sensibility. But is this opinion
devoid of foundation? or is it explicable on
the ground of the deposition of fat, which
penetrates every part of the skin; and is accu-
mulated in a dense layer beneath it, so as to
enfeeble the sensibility of the surface, accord-
ing to the common belief. This is the opinion
to which we have arrived. With respect to
the Balenide no difficulty exists on account
of the thickness and horny texture of the epi-
dermis.

[According to Hunter’s views the reticular
network containing the blubber, which he de-
scribes as fine in the Porpoise, Spermaceti,
and large Whale-bone Whale ( Balena ), and
coarse in the Grampus and small Whale-bone
Whale ( Balenoptera), forms part of the skin;

CETACEA.

for he observes that “ the cutis seems to be
the termination of the cellular membrane of _
the body more closely united, having smaller
interstices and becoming more compact,” and
that the distinction between the skin and cel-
lular membrane is much less obvious in fat
than in lean animals; “ for the cells of both
membrane and skin being loaded with fat, the
whole has more the appearance of one uniform
substance. This uniformity of the adipose —
membrane and skin is most observable in the
Whale, Seal, Hog, and the Human Species.”*]

In the Balenoptere the integument covering
the ventral surface of the neck, thorax, and
anterior part of the abdomen, is disposed in
longitudinal folds, about five-eighths of an
inch in breadth in the contracted state. The
skin is very soft in the insterstices of the folds,
and covered there with a thinner cuticle: it
possesses great elasticity over the whole of the
aphee surface. A panniculus carnosus ad-

eres closely to this part of the skin, but is
separated by a loose cellular membrane from
the deep-seated muscles; in which space the
blubber is in smaller quantity than on the dorsal
and lateral parts of the body. |

Besides the adipose substance which is ac-
cumulated beneath the integument, another
secretion of a peculiar kind, called Sperma-
ceti, which is analogous in many of its pro-
perties to the adeps, is met with in certain ~
species of Cetacea, but more particularly in
the genera Catodon and Physeter, which are
hence termed Spermaceti Whales. Of this
substance Mr. Hunter gives the following
account from a dissection of a recent specimen
of one of these Whales.

[ “‘ What is called spermaceti is found every
where in the body in small quantity, mixed
with the common fat of the animal, bearing a
very small proportion to the other fat. In the
head it is the reverse, for there the quantity of
spermaceti is large when compared to that of
the oil, although they are mixed, as in the ~
other parts of the body.

“ As the spermaceti is found in the largest
quantity in the head, and in what would ap-
pear on a slight view to be the cavity of the
skull, from a peculiarity in the shape of that
bone, it has been imagined by some to be the
brain. =

“ These two kinds of fat in the head are con-
tained in cells, or cellular membrane, in the —
same manner as the fat in other animals; but —
besides the common cells there are larger ones,
or ligamentous partitions going across, the
better to support the vast load of oil, of
which the bulk of the head is principally
made up. | a

“There are two places in the head wher
this oil lies; these are situated along its
and lower part: between them pass’ the
trils, and a vast number of tendons going
the nose and different parts of the head.

“ The purest spermaceti is contained in
smallest and least ligamentous cells: it li
above the nostril, all along the upper part

a.

* Ibid, p. 395. —

CETACEA.

the head, immediately under the skin, and
common adipose membrane. These cells re-
semble those which contain the common fat in
the other parts of the body nearest the skin.
That which lies above the roof of the mouth,
or between it and the nostril, is more inter-
mixed with a ligamentous cellular membrane,
and lies in chambers whose partitions are per-
pendicular. These chambers are smaller the
nearer to the nose, becoming larger and larger
towards the back part of the head, where the
spermaceti is more pure.

“ This spermaceti, when extracted cold, has
a good deal the appearance of the internal
structure of a water melon, and is found in
rather solid lumps.

“ About the nose, or anterior part of the
nostril, I discovered a great many vessels,
having the appearance of a plexus of veins,
some as large as a finger. On examining them,
I found they were loaded with the spermaceti
and oil; and that some had corresponding
arteries, They were most probably lym-
phatics ; therefore I should suppose, that their
contents had been absorbed from the cells of
the head. We may the more readily suppose
this, from finding many of the cells, or cham-
bers, almost empty; and as we may reason-
ably believe that this animal had been some
time out of the seas in which it could procure
proper food, it had perhaps lived on the super-
abundance of oil.

“The solid masses are what are brought
home in casks for spermaceti.

“TI found, by boiling this substance, that
I could easily extract the spermaceti and oil
which floated on the top from the cellular
membrane. When [ skimmed off the oily
part, and let it stand to cool, I found that the
spermaceti crystallised, and the whole became
solid; and by laying this cake upon any
spongy substance, as chalk, or on a hollow
body, the oil drained all off, leaving the sper-
maceti pure and white. These crystals were
only attached to each other by edges, forming
a spongy mass; and by melting this pure
spermaceti, and allowing it to crystallise, it
was reduced in appearance to half its bulk,
the crystals being smaller and more blended,
get peed less distinct.
_ _“ The spermaceti mixes readily with other
oils, wh.le it is in a fluid state, but separates
or crystallises whenever it is cooled to a certain
degree ; lke two different salts being dissolved
in water, one of which will crystallise with a
less degree of evaporation than the other; or,
if the water is warm, and fully saturated, one
of the salts will crystallise sooner than the
other, while the solution is cooling. I wanted
to see whether spermaceti mixed equally well
with the expressed oils of vegetables whea
warm, and likewise separated and crystallised
when cold, and on trial there seemed to be
no difference. When very much diluted with
the oil, it is dissolved or melted by a much
: smaller degree of heat than when alone ; and
this is the reason, perhaps, that it is in a fluid
State in the living body.

“If the quantity of spermaceti is small in

591

proportion to the other oil, it is, perhaps, nearly
i that proportion longer in crystallising ; and
when it does crystallise, the crystals are much
smaller than those that are formed where the
proportion of spermaceti is greater. From the
slowness with which the spermaceti crystallises
when much diluted with its oil, from a con-
siderable quantity being to be obtained in that
way, and from its continuing for years to crys-
tallise, one would be induced to think, that
perhaps the oil itself is converted into sper-
maceti,

“ It is most likely, that if we could dis-
cover the exact form of the different crystals
of vils, we should thence be able to ascertain
both the different sorts of vegetable oils, much
better than by any other means; in the same
manner as we know salts by the forms into
which they shoot.” *]

Orcans or GENERATION.—The organs con-
cerned in the reproduction of the species do
not exhibit the same type of conformation in
the Phytophagous as ih the Zoophagous species.
In the former the mamme are pectoral, in the
latter inguinal or rather pudendal, since they
are situated on each side of the vulva: in both
orders their number never exceeds two. The
vulva, which resembles in its form that of the
Ruminvants, presents nothing peculiar in its
Structure.

The penis is attached to the rudimental
bones of the pelvis; in the Phytophaga the
glans is complicated, but in the Zoophaga it is
of a simple elongated fusiform shape; in all
the species it is provided with a prepuce,

[ According to Hunter, the parts of generation
in both sexes of this order of animals come
nearer in form to those of the Ruminants than
of any others; and this similarity is, perhaps,
more remarkable in the female than in the male;
for their situation in the male must vary on
account of the modification of the external
form of the body.

The testicles (a, a, figs. 277, 278) retain the
situation in which they were formed, as in
those quadrupeds in which they never come
down into the scrotum. ‘They are situated
near the lower part of the abdomen, one on
each side, upon the two great depressors of the
tail. At this part of the abdomen, the testicles
come in contact with the abdominal muscles
anteriorly.

The vasa deferentia (c, c) pass directly from
the epididymis (b, b) behind the bladder (d, d)
or between it and the rectum (e) into the
urethra (f); and there are no bags similar to
those called vesicule seminales in certain other
animals.

The structure of the penis is nearly the
same in them all, and formed much upon the
same principle as in the quadruped. It is
made up of two crura (g, g), uniting into one
corpus cavernosum, and the corpus spongiosum
seems first to enter the corpus cavernosum.
In the Porpoise, at least, the urethra is found
nearly in the centre of the corpus cavernosum ;
but towards the glans seems to separate or

- * Philos, Trans. 1787, p. 390.

592

Fig. 277.

Male Organs of a Porpesse.

emerge from it, and becoming a.distinct spongy
body, runs along its under surface, as in qua-
drupeds (h). Thecorpus cavernosum in some
is broader from the upper part to the lower
than from side to side; but in the Porpoise
(fig. 277) it has the appearance of being
round, becoming smaller forwards, so as to
terminate almost in a point some distance from
the end of the penis. The glans does not
spread out as in many quadrupeds, but seems
to be merely a plexus of veins covering the
anterior end of the penis, yet is extended a

Fig. 278.

Male Organs of a Dolphin.

CETACEA.

good way further on, and is in some not more |
than one vein deep. ¢

The crura penis are attached to two bones,
which are nearly in the same situation and in
the same part of the pelvis as those to which
the penis is attached in quadrupeds; but these
bones are only for the insertion of the crura, —
and not for the support of any other part, like
the pelvis in those animals which have poste-
rior extremities, neither do they meet at the
fore part, or join the vertebra of the back.

The erectores penis (g, g, fig. 277) are very
strong muscles, having an origin and insertion
similar to those of the human subject.

The prostatic portion of the urethra Cp Sig.
278) is surrounded by a muscle of prodigious
thickness (k, k), destined to compress and
forcibly expel the contents of that part of the
canal. ;

The acceleratores muscles (1) are likewise
very strong; and there isa pair of strong and
long muscles (m, fig. 277.) arising from the __
anus, and passing forwards to the bulb of the
penis, that run along the under surface of the
urethra, and are at last lost or inserted in the
corpus spongiosum. These muscles draw the
penis into the prepuce, and throw that part of }
the penis that is behind its insertion into a

.

serpentine form. These muscles are common
to most animals that draw back the penis into
what is called the sheath, and may be called
the retractores penis.

The female organs in the Phytophagous
Cetacea have been described by Steller as
they exist in the Rytina, and by Home in
the Dugong; the latter author has given a
figure of the uterus with part of the vagina:
(see fig. 279.) In both species the vagina (a)
is characterized by the longitudinal ruge of
its inner surface. The body of the uterus (c)
commences by a single os tince (6) in the

Fig. 279.

Uterus of the Dugong.

Dugong, and gives off the cornua uteri (d, d)
at right angles.* The structure of the Fallo-
pian tubes and ovaries is not described. Stel
states that in the Rytina they resemble those
the Mare. The vulva he describes as of a
angular form, with the clitoris, which is
gristly texture, and an inch and a half |

tee
Ps

* See Home, in Phil, Trans. 1820, p: 321.55 z

=i
a

' tubes,

- Opposite

CETACEA. ~ 593

situated at the anterior broad part of the open-
ing, which is eight inches anterior to the anus.

In all the females of the zoophagous tribe
of Cetacea which Hunter examined, the parts
of generation were very uniformly the same ;
consisting of the external opening, the vagina,
the body and two horns of the uterus, Fallopian
mbrie, and ovaria.

‘< The external opening is a longitudinal slit,
or oblong opening, whose edges meet in two
ints, and the sides are rounded off,

so as to form a kind of sulcus. The skin and

parts on each side of this sulcus are of a looser

texture than on the common surface of the
animal, not being loaded with oil, and allow-

ing of such motion of one part on another as

admits of dilatation and contraction. The va-
gina passes upwards and backwards towards

- the loins, so that its direction is diagonal re-

mR the cavity of the abdomen, and then
ivides into the two horns, one on each side of
the loins; these afterwards terminating in the
Fallopian tubes, to which the ovaria are at-
tached. From each ovarium there is a small
fold of the peritoneum, which passes up to-
wards the kidney of the same side, as in most

quadrupeds.

“ The inside of the vagina is smooth for about
one-half of its length, and then begins to form
something similar to valves projecting towards
the mouth of the vagina, each like an os tince :
these are about six, seven, eight, or nine in
number. Where they begin to be formed, they
hardly go quite round, but the last are com-

lete circles. At this part, too, the vagina
omes smaller, and gradually decreases in
width to its termination. From the last pro-
jecting part, the passage is continued up to the
opening of the two horns, and the inner sur-
face of this last part is thrown into longitudinal
ruge, which are continued into the horns.
Whether this last part is to be reckoned com-
mon uterus or vagina, and that the last val-
vular part is to be considered as os tince, I do
not know; but from its having the longitudinal
ruge, I am inclined to think it is uterus, this
structure appearing to be intended for dis-
tinction.

The horns are an equal division of this part;
they make a gentle turn outwards, and are of
considerable length. Their inner surface is
thrown into longitudinal ruge, without any
small protuberances for the cotyledons to form
upon, as in those of ruminating animals;
and where they terminate the Fallopian tubes

“ In the Bottle-nose Whale ( Delphinus Tur-
sio), where the Fallopian tubes opened into
the horns of the uterus, they were surrounded
by pendulous bodies hanging loose in the
horns.

“ The Fallopian tubes, at their termination in
the uterus, are remarkably small for some in-
ches, and then begin to dilate rather suddenly;
and the nearer to the mouth the more this dila-
tation increases, like the mouth of a French
horn, the termination of which is five or six
inches in diameter. They are very full of lon-
gitudinal ruge through their whole length.

“ The ovaria are oblong bodies, about five
inches in length; one end attached to the
mouth of the Fallopian tube, and the other
near to the horn of the uterus. They are irre-
gular on their external surface, resembling a
capsula renalis or pancreas. They have no
capsula but what is formed by the long Fallo-
pian tube.

‘“¢ How the male and female copulate I do not
know; but it is alleged that their position in
the water is erect. at that time, which I can
readily suppose may be true; for otherwise, if
the connexion is long, it would interfere with
the act of respiration, as in any other position
the upper surface of the heads of both could
not be at the surface of the water at the same
time. However, as in the parts of generation
they most resemble those of the ruminating
kind, it is possible they may likewise resemble
them in the duration of the act of copulation,
for I believe all the ruminants are quick in
this act.

“ Of their uterine gestation I as yet know
nothing, but it is very probable that they have
only a single one ata time, there being only
two nipples. This seemed to be the case with
the Bottle-nose Whale, caught near Berkeley,
which had been seen for some days with one
young one following it, and they were both
caught together.

“The glands for the secretion of milk are
two, one on each side of the middle line of the
belly at its lower part. The posterior ends,
from which go out the nipples, are on each
side of the opening of the vagina in small sulci.
They are-flat bodies lying between the external
layer of fat and abdominal muscles, and are of
considerable length, but only one-fourth of that
in breadth. They are thin, that they may not
vary the external shape of the animal, and have
a principal duct, running in the middle through
the whole length of the gland, and collecting
the smaller lateral ducts, which are made u
of those still smaller. Some of these lateral
branches enter the common trunk in the direc-
tion of the milk’s passage, others in the con-
trary direction, especially those nearest to the
termination of the trunk in the nipple. The
trunk is large, and appears to serve as a reser-
voir for the milk,* and terminates externally in
@ projection, which is the nipple. The lateral
portions of the sulcus which incloses the nipple
are composed of parts looser in texture than
the common adipose membrane, which is pro-
bably to admit of the elongation or projection
of the nipple. On the outside of this there is
another small fissure, which I imagine is like-
wise intended to give greater facility to the
movements of all these parts. The milk is
probably very rich; for in that caught near
Berkeley with its young one, the milk, which
was tasted by Mr. Jenner, and Mr. Ludlow,
surgeon, at Sodbury, was rich like cow’s milk
to which cream had been added.

“The mode in which these animals must

* The description of this structure has lately
been reproduced as a new discovery by Geofiro
St. Hilaire.

594
suck would appear to be very inconvenient for
respiration, as either the mother or young one
will be prevented from breathing at the time,
their nostrils being in opposite directions, there-
fore the nose of one must be under water, and
the time of sucking can only be between each
respiration. The act of sucking must likewise
be different from that of land animals; as in
them it is performed by the lungs drawing the
air from the mouth backwards into themselves,
which the fluid follows, by being forced into
the mouth from the pressure of the external air
on its surface; but in this tribe, the lungs
having no connexion with the mouth, sucking
must be performed by some action of the
mouth itself, and by its having the power of
expansion.”

Much stress has recently been laid on the
supposed existence which the muscles sur-
rounding the mammary gland. afford in the act
of suckling by compressing the gland and
ejaculating the milk accumulated in the dilated
receptacle above described ; but when we con-
sider how great the pressure of the surrounding
water must be upon the extended surface of the
mammary gland, we may readily conceive that
when the nipple is grasped by the mouth of the
young, and the pressure removed from it by
the retraction of the tongue, the milk will
be expelled in a copious stream by means of
the surrounding pressure alone, independently
of muscular aid.

The intimate structure of the mammary gland
in the Zoophagous Cetacea is essentially the
same as in the Ornithorhynchus, being compo-
sed of an innumerable quantity of small elon-
gated cecal tubes; these are, however, shorter
than in the Ornithorhynchus, and their glandu-
lar parietes are firmer; they are well shown in
the figure of the mammary gland of a young
Piked Whale, ( Balenoptera Rostrata,) given
by Miiller in his pl. xvil. fig. 2, and according
to that author present, after the Ornithorhyn-
chus, the simplest structure of the mammary
gland in the entire mammiferous series of ani-
mals. |

BIBLIOGRAPHY.—Aristotle, Historia de animali-
bus. Bartholinus, Cetorum genera, Historia anato-
mica, Cent. iv. p. 272-285; De oculo Balene et
Dentibus, in Acta Hafniens. vol. ii. p. 67-70; De
Unicornu observationes nove, 12mo. 1645, Achre-
lius, Cetographia, sive Disseitatio Historico-physica
de Cetis, Abox, 1683, 8vo. Ray, An account of
the dissection of a Porpesse, Philos. Trans. 1671,
vol. vi. p. 2274. Major, De Anatome Phocene,
vel Delphini Septentrionalium, Ephem. Acta Nat.
Cur. Dec. 1, Ann. 3, p. 22-32; De respiratione
Phocene, vel Tursionis, Ephem. Acad, Nat. Curios.
Dec. i. Ann. 8, p. 4,5. Tyson, Phocena, or the
anatomy of a Porpess, 4to. 1680. Sibbald, Pha-
lainologia nova, &c. Edinb. 1692, 4to. ; Scotia illus-
trata, fol. 1684. De la Motte, Anatome Phocene,
in Klein Hist. piscium naturalis, p. 24-32, Ticho-
nius, Monoceros piscis haud monoceros, Hafnia.
1706. Dudley, An essay on the natural history of
Whales ; with a particular account of the ambergris
found in the Spermaceti Whale, Phil. Trans, 1725.
Steller, De Bestiis marinis, Nouveaux Mémoires de
V’ Academie de Potent t.ii. 1751. Daubenton,
Descriptions des tétes de Lamantins et de Dugong,
Hist. Nat. de Buffon, t. xiii. 1765. Linneus,
Systema Nature, Ed. xii. 1766. Pennant, Brit.

CHEIROPTERA. ;

Zoology, 1776. Fabricius, ( Otho,) Fauna Gre

landica, 1780, Pallas, Spicilegia Zoologica, 1767 to
1780. Hunter, Observations on the structure and

ceconomy of Whales, Philos. Trans. 1787. Baussard,

Mémoire sur un Cétacé échoué prés de Honfleur, ’

Journal de Physique, 1789. Cuvier, Geo. Sur les

narines des Cétacés, Bulletin des Sciences par la j

Societé Philomathique, Juillet, 1797; Legons d’Ana- |

tomie Comparée, tom. i. v. 1799-1804; Recherches

sur les Ossémens Fossiles, 4to. 2d ed. t. v. pt. i.

1823; Régne Animal, &c. 1817, 2d ed. 1829.

Lacépede, Hist. Nat. des Cétacés, 1803. Scoresby, 4

Account of the Balena Mysticetus, &c., Wernerian

Transactions, vol. i. p. 578; An account of the

Arctic Regions, 1820. Home, Lectures on Compa-

rative Anatomy, 4to. 1814-1828. Albers, Icones ad

illustrandam Anatomen Comparatam, fol. Camper,

Observations Anatomiques, &c. sur plusieurs es- ~

péces de Cétacés, Paris, 1820. Rudolphi, Mémoires

de |’Academie de Berlin, 1820. Barclay on the

anatomy of the Beluga, Trans. Wernerian Society,

vol. iii. Eichwald, Observ. Anatom. sur un jeune

Marsouin, Mémoires de l"Acad. de Petersb. t. ix.

1824. Blainville, Note sur un Cétacé échoué au

Havre, Nouvean Bulletin des Sciences, Sept. 1625.

Jacob, Anatomy of the Delphini, Dublin Philo-

sophical Journal, 1826. Tiedemann, Hirn des

Delphins mit dem des Menschens vergleichen, in

Zeitschrift fur Physiologie, Band ii. Hefti. 1826.

Baer, Anatomie des Braunfisches, Oken’s Isis, 1826;

Uber das Gefass-system des Braunfisches, Nova

Acta Phys. Med. t. xvii. parsii. 1835. Rapp,

Natur Weissenschaft abhandlung, 1827; Beitrage

zur anatomie und physiologie des Wallsfisches, in

Meckel’s Archiv. ftir Physiologie, 1830. Haber,

Snr le soufflage des Cétacés, Isis, 1827. Schegel,

Mémoire sur le Baleinoptére de la Mer Arctique

échoué, 1826, &c., Mém. de 1’Institut Royal des

Pays-Bas, 1828. Rousseau, Moustache chez les

foetus de Dauphins et Marsouins, Annales des

Sciences Naturelles, 1830. D’Orbigny, Notice sur

un nouveau genre de Cétacés, Nouv. Annales du

Muséum, t. iii. 1834. Breschet & Roussel de Vauzéme,

Recherches anatomiques et physiologiques sur les

appareils tégumentaires des animaux, in Annales

des Sciences Nat. 1834, and subsequently collected

into 1 vil. 8vo. Nouvelles Recherches sur la Peau,

Paris, 1836. Owen, Description of the Hunterian

anatomical preparations of the Cetacea in the

‘ Descriptive and Illustrated Catalogue of the A

Physiological Series in the Museum of the College

of Surgeons, London,’ 1832-1835. Cuvier, Fr.

Histoire naturelle des Cétacés, 8vo. Paris, 1836.
The preceding article has been derived from the work
ast named in the Bibliography, with the addition of 2

the extracts from Mr. Hunter's papers und the other ::

passages included between brackets. ¥

(F. Cuvier.) se

CHEIROPTERA, (from yee, manus, wregoy,
ala, ) Bats, Fr. Chauvesouris,Germ. Fledermau-
ser, an order of mammiferous quadrupeds, «
consisting of such as have a generally in-
sectivorous type of dentition, with the extremi-
ties connected together by an aliform expansion
of the integuments, for the purpose of flight.
The question whether this group, as well as
that of the Carnivora and that of the Iy-
SECTIVORA, ought to be considered as forming
a single order according to the method of
Cuvier, has been already sufficiently adverted
to under the head Carnivora; and it needs —
only to be now observed that if there were —
sufficient ground for giving to the last-men- —
tioned group a separate consideration, either —
on account of expediency and convenience, —
or on that of natural arrangement, the same —

CHEIROPTERA.

reasons hold good, in the present case, in an
equal, if not a superior degree.

The distinctions by which the present order
is separated from all others are so marked,
and the general similarity in the organization of
its component groups is so striking, as greatly
to facilitate and shorten the necessary detail
of the organization.

There appears to be a great and obvious
objection to the usual location of the remark-
able genus Galeopithecus amongst the Cheiro-
ptera; there are so many important parts of
its organization in which it clearly resembles
the more insectivorous forms of the Quadru-
mana, not only in the peculiarities of its
osteology, but in many other not less essential
points, that I have preferred following the
change suggested by Blainville, and subse-
quently adopted by 'Temminck, to the arrange-
ment of Cuvier and of most other zoologists.
It may undoubtedly be considered as an oscu-
lent form, leading from the Quadrumanous
order, by the Makis, &c. to the present group ;
but it cannot but be acknowledged by any
one who has attentively marked its anatomical
structure, that the affinity of this genus to the
Quadrumana is more intimate than that by
which it approaches the Bats; though perhaps
it would be going too far to say, with
Temminck, that it bears the same relation
to the Quadrumana as Petaurista to the Mar-
supiata, or Pteromys to the Rodentia. Thre
latter genera are not even on the confines
of their respective orders, nor do they offer
any important aberration from the typical struc-
ture; but in the present case there are several
characters which indicate an interesting ap-
proach towards the order from which it has
very properly been removed.

Omitting, then, the genus Galeopithecus,
the Cheiroptera form, without perhaps a single
exception, the most distinctly circumscribed
and natural group to be found in the whole

595

class of the Mammifera. The characters by
which the order thus restricted is distinguished
are as follow :—

General form disposed for flight; an ex-
pansion of the integument stretched between
the four members, and the fingers of the an-
terior extremities, which are greatly elongated
for that purpose; the flying membrane naked,
or nearly so, on both sides. Mamme pectoral,
clavicles very robust; fore-arm incapable of
rotation, in consequence of the union of the
bones of which it is composed.

The Cheiroptera consist of two distinct
groups; of which the first, containing the
genera Pteropus and Cephalotes, is frugivorous,
and distinguished by the molar teeth being
obliquely truncated and longitudinally grooved,
and by the existence of a third phalanx, which
is in general provided with a little nail on the
index or second finger, and by the absence or
rudimentary condition of the tail. The second,
consisting of the insectivorous bats, ( Chauve-
souris vruies, Cuv. Vespertilionide, Gray,)
have the molares furnished with acute points,
similar to those of other insectivora.

Osteology.—The evident object in the general
structure of the skeleton of the Cheiroptera
(fig. 280) is to combine as great a degree
of lightness as possible with great extension
of the anterior extremities, for the purposes
of flight. The general form of the head differs
in the two grand divisions of the Cheiroptera
by the different lengths of the cranium; and
this diversity is exactly conformable with that
which exists in other families. The frugivorous
group (fig. 281, 282, 283) has a much more
elongated form than the insectivorous (fig.
284, 285, 286), arising principally, though
not wholly, from the form of the maxillary
and intermaxillary bones.

The cranium is generally rounded, and rather
broad. The posterior aspect more or less con-
vex in different groups ; in some overhanging

4,

~
~~ -==--”

=
“s.

ee,

Skeleton of Pteropus.

596 CHEIROPTERA.

the occipital foramen, in others not so. The
occipital crest is triangular, stronger in the
insectivorous than in the frugivorous form.
In many there is also a longitudinal crest.
The face is broad. The orbits are not com-
plete in either group, and the ¢emporal fossa
is large, but the zygoma in many very slender ;
in some it is horizontal, in others slightly
convex above. The nasal opening is very
considerable; and in many whole genera, as
in Rhinolophus, in Plecotus, and several others,
in consequence of the intermaxillary bones not
meeting each other, it is not closed at the
lower part. In the genus Pteropus, and some
others, as is seen in fig. 282, 283, though the
intermaxillary bones meet in front, yet, as the
arch is very small and narrow from before
backwards, the palatine foramina unite and
form a single large opening.

From the extreme thinness of the cranial
bones, the internal surface corresponds exactly
with the external, and there is no vestige of
a bony tentorium, which is so strong in many
of the Carnivora.

The frontal bone in the genus Pteropus
presents a prominent orbitar process; it re-
sembles that of Man, and of the Quadrumana,
in the circumstance of the two portions be-
coming early united. The parietals, also,
unlike those of the examples just named, form
but a single bone.

The temporal bone has a very extensive
development of its acoustic portion; a cha-
racter which is of the utmost importance to
their peculiar habits, as the organ of hearing

_ Cranium of Pteropus.

requires to be extensive in those animals which
prey by night, and especially in such as feed
upon insects and pursue them on the wing. |

The occipital bone is remarkable from the
narrowness of its body, the transverse direction
of the condyles, the short, thin, and convex

\) form of its squamous portion, and particularly
] from the unparalleled proportionate size of the

occipital foramen, which is nearly vertical and
rounded.

Fig. 284. Fig. 285.

Cranium of Phyllostoma.

The jugal bone is small in most of the bats
and very strait.

The superior maxillary bone is considerably
elongated in this order, particularly in the
frugivorous genera. ‘The difference in this
respect which exists between the frugivorous
and insectivorous forms is shewn in the cranium
of a Pteropus belonging to the former (fig.
281, 282, 283), and a Phyllostoma to the
latter group (fig. 284, 285, 286). In the
former case, the portion occupied by the teeth
fully equals in length the portion of the cranium
posterior to it; in the latter it is little more
than as two to three. The number of teeth con-
tained in this bone varies considerably. There
is, however, always a single canine tooth on
each side, which is tolerably robust and sharp.
The molares of the insectivorous Bats are
always shorter than those of the frugivorous,
and are furnished with sharp points, the latter
being truncated and longitudinally grooved.
They vary in number from 8 to 8, or §.

Theintermaxillary bones are always very small
and short; they contain small incisores, varying
in number according to the genera, from two
to four in the upper, and in the lower jaw from
two to six, there being always either the same
numberin the two jaws, or two more in the lower
than in the upper; thus there is always one
of the following formule—3 344. The articu-

lation of the lower jaw is transverse. The

ascending ramus, with its coronoid process, is
large and strong, rising very high above the
level of the condyle.

The vertebral column.—The cervical verte-

bre are in general very little raised, but they
are developed laterally, so as to
broadest portion of the whole vertebral column,

present the

»- - yas at ps6 @ a eae * — >
}r or

Al

CHEIROPTERA.

and the spinous processes are wanting from
the second to the sixth vertebra. The Aélas
is large, the dentata small, and its spinous
process inconsiderable. The dorsal vertebre
are of a very simple construction; they are
almost without spinous processes, which are
replaced by a small tubercle: the bodies are,
however, much compressed at the sides, so as
to form a sort of crest. The vertebral canal
is very large in this region. These vertebre
are twelve in number in both forms, excepting
in some species of the single genus Vespertilio,
in which they are only eleven. The lumbar
vertebre retain the peculiar characters which
have been mentioned as belonging to the
dorsal. They are elongated, and still almost
devoid of spinous processes; they are also
compressed into a sort of continuous crest.
The number of these vertebre is four in
Pteropus, five in Phyllostoma and Vespertilio,
six in Rhinolophus, seven in Noctula.

Lhe sacrum is particularly elongated and
narrow, and the spinous processes large. The
number of sacral vertebre varies much. In
Pteropus (fig. 280) there is but one. In the
other genera they are either three or four. In
Pceropus the sacrum is united at its extremity
to the tuberosities of the ischium.

The coccygeal vertebre are slender, elon-
gated, and nearly cylindrical; the tail being
always included within the flying membrane,
the only use of this part is to assist in sup-

rting the interfemoral portion of that mem-

rane. In most the tail reaches to its margin,
in some much beyond, in others only half-way,
and in Pteropus (fig. 280) there is not the least
appearance of a tail, there is not even a rudi-
ment of a coccygeal bone. The number of these
vertebre is but six in Noctula, twelve in Ves-
pertilio and some others.

The number of vertebre in the whole co-
lumn is said to be less in Péteropus than in any
other mammiferous animal, being only twenty-
four, namely, 7C+-12D-+-4 L+1S=24.

The ribs are the same in number as the dorsal
vertebre. The first rib is very short and
remarkably broad, and its cartilage, which is
ossified, is still more so. The rest of the ribs
follow the usual variations of form.

The Bats are remarkable for the extraordinary
proportional length of their ribs, in which they
probably exceed all other Mammifera.

The sternum is altogether greatly developed
in the whole of this order. Its length is con-
siderable, and this circumstance,with the length
of the ribs, tends to afford a great protection
to the thorax in the violent movements re-
quired by the act of flight. But the most re-
markable peculiarity exhibited in the structure
of this part, is the extraordinary lateral deve-
lopment of the anterior portion of this bone,
termed the manubrium. This expansion is
conspicuous in all the Bats, and appears to be
intended to afford the strongest possible attach-
ment for the clavicles,which are also very much
develo In the genus Rhinolophus (the
Horse-shoe Bat), this expansion seems to have
reached its maximum of development. Its
breadth is four times as great as its length, and

597

yet it is nearly as long as the whole remaining
portion of the sternum. ‘The inferior surface
of the manubrium is also furnished with a
crest, which is continued, though much smal-
ler, on the next piece of the sternum ; it varies
in size in the different genera. The remaining
bones composing the sternum are of nearly equal
size.

The anterior extremity is the part of the
skeleton which in the true Cheiroptera offers
the most remarkable deviation from the nor-
mal form, especially in the metacarpal and pha-
langeal bones.

The clavicle, from the extensive motion of
the anterior extremities, requires to be much
elongated in these animals; some of which in
fact exhibit proportionally a greater develop-
ment of this bone than is to be found in any
other order. It is always arched above and
intimately articulated both to the scapula and
to the sternum, and in some species is half as
long as the greatly elongated humerus. As far
as I have had an opportunity of observing,
the clavicle, as well as the other portions of
this extremity, is more developed in the in-
sectivorous than in the frugivorous Bats, for the
very Obvious reason that the former require
more extensive powers of flight in the pursuit
of their swift and active prey, than the latter
in merely flying from place to place, in search
of their stationary sod ;

The scapula is also developed to the greatest
extent, and particularly in the insectivorous
Bats. It is greatly elongated towards the base
and posterior angle, which in some species
reaches nearly to the last rib. The inner
surface is very concave, and the fosse above
and below the spine are deep, for the attach-
ment of the powerful muscles which are in-
serted to it.

The humerus is very long, slender, and cy-
lindrical, as may be observed in the skeleton
of Pteropus in fig.280. The head of the bone
is round and large. The whole anterior part
of the inferior articulation or elbow-joint cor-
responds to the head of the radius.

he fore-arm consists, as in the other mam-
mifera, of the radius and the ulna. The latter
bone is, however, in all the Cheiropiera ex-
ceedingly small, and in some merely rudimen-
tary. In several species of Vespertilio, for
instance, it forms nothing more than a flat
process, only partially separated from the
radius. In the example shewn at fig. 280
it is more considerable ; but even here it
presents nothing more than a small styliform
bone, united to the radius at the head, and
diminishing to a thin point, towards the
carpal extremity; the olecranon too is wholly
wanting.

The radius, like the other bones of the an-
terior extremity, is remarkably elongated, and
rather robust. The absence of rotation in the
forearm of these animals forms an admirable
adaptation to their habits. Not only would
the pronation and supination of the hand be
wholly useless to them, but at every impulse
of their flight such a motion would deprive
the whole limb of its resistance to the air, or

598

it would require the constant exertion of such
a degree of antagonizing muscular force to
prevent it, as would be incompatible with the
essential structure of these organs of flight.

The carpus is of a very peculiar structure.
The first series of bones consists but of two ;
one very large, on which the radius rests, and
which is probably formed of the three outer
bones, the scaphoid, the semilunar, and the
cuneiform bones; the other extremely small,
which is undoubtedly the pisiform, on the ulnar
side.

The second series consists of the four bones
of which it is usually constituted.

The metacarpal bones and phalanges of all
the fingers excepting the thumb are extremely
elongated. They extend outwards and down-
wards in a slightly curved direction to the
margin of the flying membrane, the second
finger being the shortest and extending to the
upper angle of the outer margin, the third,
fourth, and fifth to the inferior margin of the
membrane. There is a slight enlargement at
the articulation of the metacarpal bones with
the phalanges; but otherwise these bones are
extremely slender and cylindrical. The thumb
is of no extraordinary length, and the ultimate
phalanx is hooked and sustains a nail, by
which the animal is enabled to climb on any
rough perpendicular surface, or to suspend
itself from some projecting part.

The pelvis is remarkably strait, rather elon-
gated, somewhat wider inferiorly. The dia
are narrow and elongated ; the ischia in several
species, instead of receding from each other,
approach so that their tuberosities touch each
other, and in some instances come in contact
with the coccygeal bones. In some species of
Pteropus, the anterior portion of the ossa pubis,
instead of meeting at the median line, recede
more or less from each other, and the space is
filled by ligament. In some species there is a
sexual difference in this respect; the two pubic
bones being in contact in the male and sepa-
rated in the female.

The sacrum and the ilia are connected by
absolute bony union at an early period. The
Jemur is of moderate length, slender and cy-
lindrical. It is turned outwards and upwards,
so that the side which is usually anterior is
directed nearly backwards. The tibia offers
no peculiarity which requires particular notice.
The fibula is exceedingly small, slender,
pointed towards its femoral extremity, and has
this singular peculiarity, that it does not rise
to the head of the tibia. In other cases where
this bone is defective, it is at its inferior ex-
tremity, but in the present case it is the supe-
rior portion which is wanting. As the femora
are directed outwards, the leg-bones are in
some measure turned round, so that the fibule
are at the inner side of the ¢ibie and a little
behind them.

The foot of the Cheiroptera does not ex-
hibit the same deviation from the normal
structure which we have seenin the hand. On
the contrary, it is not extraordinarily developed,
and the different parts of which it is composed
are in the usual relative proportions.

CHEIROPTERA.

The tarsus is composed of the usual bones.
There is a peculiarity in the heel, however,
which is worthy of notice. There is a long,
slender, pointed, bony process from the pos-
terior part of the foot which is inclosed within
the folds of the margin of the interfemoral
membrane, and extends about half-way to the
tail. Whether this process is a portion of the

. os calcis, according to Cuvier, or a distinct

bone according to Daubenton, it is perhaps
difticult to decide; but the opinion of Meckel
is probably the correct one, that it is nothing
more than a development of the tuberosity of
that bone, remaining disunited from its body.

The metatarsal bones are rather short, slender,
and of nearly equal length.

The phalanges of the five toes are nearly
equal, the inner toe reaching almost to the
same length as the others, in consequence of
the greater elongation of its first phalanv.
The ultimate phalanges are furnished with
hooked nails, by which these animals constantly
suspend themselves when at rest with the head
downwards.

The whole of this structure is so perfectly
adapted to the peculiar habits of the animals,
as to require no comment. The great deve-
lopment of the ribs, sternum, and scapula, for
the attachment of strong muscles of flight, the
length and strength of the clavicle, the exten-
sion of all the bones of the anterior extremities,
all admirably tend to fulfil their obvious end.
The existence of a tail for the support and
extension of the interfemoral membrane, which
is found in the insectivorous Bats, compared
with its absence or comparative inefficiency in
many of the frugivorous, also points out an
interesting relation to the different habits of the
two groups, the former structure being calcu-
lated to afford a powerful and effective rudder
in guiding their rapid and varying evolutions
in the pursuit of their insect food.

The general nervous system in the Cheiro-
ptera does not exhibit any very remarkable
peculiarity, but some of the organs of sense
require a particular notice. .

Organs of the Senses— The organ of vision
is principally remarkable for its diminutive
size. The eye in many of the insectivorous
group, in which the external ear is very largely
developed, is placed within the margin of the
auricle and almost concealed by hair. In the
frugivorous group, on the other hand, it is
of the usual proportional size. I'he organ
of hearing, on the contrary, though in the
latter forms not more developed than in most
other quadrupeds, in the former seems to take
the place of the diminutive organ of vision,
being greatly extended both in its external and
internal organization. The external ear in
Pteropus is of the usual form and dimensions,
and the eminences are not in any respect extra-
ordinary: but in most of the insectivorous Bats —
the conch of the ear is enormously large; in
many species being considerably larger and —
longer than the head, and in the common long- —
eared Bat of this country, Plecotus auritus, it
is nearly as long as the body. The tragus is
proportionally larger than in any other animals ;

CHEIROPTERA.

in most species it is more or less lanceolate in
its form; in Vespertilio spasma it is forked,
and in the great Bat of Britain, Vespertilio
noctula, it is short, blunted, with a rounded
head, thickish, and I have observed it beset
with numerous minute glands, which do not
occur in those species having the thin lan-
ceolate form of this part. Its use is probably
to prevent the rush of air into the open ear
during flight; and where it does not exist,
as in the Horse-shoe Bats ( Rhinolophus ), its
place is supplied bya large rounded lobe which
is capable of still more effectually closing the
external meatus.

In the internal ear there is an equal diver-
sity of structure in the two groups in question.
The cochlea is particularly developed in the
insectivorous group; being much larger than
the semicircular canals; the circumference of
that of Rhinolophus is no less than four times
the circumference of the canals, and its cavity
exhibits ten times the diameter of one of them.
In Pteropus this disproportion is very much
less. The meatus is short and, as well as the
tympanic cavity, extremely large and open.

But it is in the sense of touch probably that
the most extraordinary and interesting pecu-

liarities are to be observed. Spallanzani hav-.

ing observed the power which these animals
possess of flying with perfect accuracy in the
dark, and of avoiding every obstacle that pre-
sents itself with the same unerring certainty as
in the light, instituted a series of experiments,
the results of which proved that bats when
deprived of sight by the extirpation of the
eyes, and, as far as possible, of hearing and
smell by the obliteration of the external pas-
sages of those senses, were still capable of
directing their flight with the same security
and accuracy as before, directing their course
through passages only just large enough to
admit them without coming into contact with
the sides, and even avoiding numerous small
threads which were stretched across the room
in various directions, the wings never, even
by accident, touching any of them. These
marvellous results led him to believe that these
animals are endowed with a sixth sense, the
immediate operation as well as the locality of
which is, of course, unknown to and unap-
preciable by us: but the sagacity of Cuvier*
removed the mystery without weakening the
interest of these curious facts, by referring to
the flying membrane as the seat of this extra-
ordinary faculty. According to this view of
the subject, the whole surface of the wings on
both sides may be considered as an enor-
mously expanded organ of touch, of the most
exquisite sensibility to the peculiar sensation
for which it is intended; and it is, therefore,
by the varied modification of the impulsion of
the atmosphere upon this surface, that the
knowledge of the propinquity of foreign bodies
is communicated. is membrane is every
where furnished with oblique or transverse
bands, consisting of lines of minute dots re-

* Legons d’Anatomie Comparée, t. ii. p 582.

599

sembling in some measure strings of very small
glands or cutaneous follicles. May there not
be some connexion between these peculiar
little bodies and the extraordinary function just
described ?

The tendency to an extraordinary develop-
ment of the dermal system is not confined to
the organs now mentioned, of the senses of
touch and of hearing. The organ of smell is
in many insectivorous Bats, as in the whole
family Rhinolophide, furnished with foli-
aceous appendages, formed of the integument
doubled, folded, and cut into the most curious
and grotesque forms. These nasal leaflets are
found principally or exclusively to belong to
a group, the habits of which are more com-
pletely lucifugous and retired than any others ;
they are found in the darkest penetralia of
caverns, and other places where there is not
even the imperfect light which the other genera
of Bats enjoy. It is probable that this deve-
lopment of skin around the nose is intended
to give increased power and delicacy to the
organ of smell, as well as to regulate the access
of the odoriferous particles, and thus to super-
sede the sense of vision, in situations where the
latter would be unavailable.

In the genus Nycteris a curious faculty is
observed, namely, the power of inflating the sub-
cutaneous tissue with air. The skin adheres
to the body only at certain points, where it is
connected by means of a loose cellular mem-
brane ; it is therefore susceptible of being raised
from the surface, on the back as well as on the
under parts. These large spaces are filled with
air at the will of the animal, by means of large
cheek pouches, which are pierced at the bottom,
and thus communicate with the subcutaneous
spaces just mentioned. When the animal
therefore wishes to inflate its skin, it inspires,
closes the nostrils, and then contracting the
cavity of the chest, the air is forced through
the openings in the cheek pouches under the
skin, from whence it is prevented from returnin
by means of a true sphincter, with which those
openings are furnished, and by large valves on
the neck and back. By this curious me-
chanism the bat has the power of so com-
pletely blowing up the spaces under the skin,
as to give the idea, as Geoffroy observes, “ of a
little balloon furnished with wings, a head, and
feet.”

The digestive organs of the Cheiroptera ex-
hibit as distinct a division into the two prin-
cipal groups before-mentioned, as any other
part of their anatomy. The teeth have been
already alluded to, and the characters of these
important organs, important as indicating, in
the most unerring manner, the nature of the
food, are well-marked in the two groups. The
flattened crowns of the molares, so similar to
those of the Quadrumana which are found to
belong to the frugivorous Bats, are strikingly
contrasted with the many-pointed tuberculous
teeth of the insect-feeders, and exhibit an in-
teresting affinity to the two important orders of
animals to which the Cheiroptera may be con-
sidered intermediate; the former division re-

600
ferring evidently to the Quadrumanous type in
the structure of the teeth, and the latter to the
type of the insectivora.
e tongue presents a peculiarity in the
genus Phyllostoma, which is worthy of being
icularly noted. It consists of a number
of wart-like elevations, so arranged as to form
a complete circular suctorial disk, when they
are brought into contact at their sides, which is
done by means of a set of muscular fibres,
having a tendon attached to each of the warts.
By means of this curious sucker, these bats
are enabled to suck the blood of animals and
the juice of succulent fruits. This power has
been attributed by mistake to some of the
genus Pteropus, merely because their tongue is
rough, and it was calculated that by means of
such a surface the skin may have been abraded.
The sLomach is no less indicative of the nature
of the aliment than the teeth; offering, in the Pte-
ropus (fig. 287), a very striking affinity to that

of many true vegetable feeders in some remote
orders, and in Plecotus (fig. 288), as complete

Fig. 288.

an identity with that of the carnivorous type.
In the former the cesophagus swells out before
it enters the general cavity, and that dilatation,
as Home observes, appears, from its structure,
to belong to the stomach. To the left of the
cesophagus there are two dilatations, the far-
thest of which has a smooth surface and thin
coats ; the other is furnished with several deep
longitudinal ruge, some of which are con-
tinued from similar ones in the cesophagus.
Four of the ruge are continued towards the
pylorus, giving a direction to the food in that
course; about one-third of the stomach to-
wards the pyloric extremity is turned back
neo itself, and the pylorus is consequently
placed externally close to the entrance of the
esophagus. At the pylorus is a very small
Opening into the intestine, which when con-
tracted seems scarcely pervious to air. Such
is the complicated form of the stomach in the
frugivorous division; whilst that of the insect-
feeders is as simple as possible, being only
divided into a cardiac and a pyloric portion
with scarcely the slightest contraction. The
intestines present a no less marked distinction.
In the Pteropus they are no less than seven
times the length of the body, whilst Vesper-

CHYLIFEROUS SYSTEM.

tilio noctula offers the shortest pr
length of the canal, it being only twice as long

_ asthe body. The latter is also wholly devoid

of a cecum.

The organs of generation.—The male organs
of the Bats bear a near relation to those of the
Quadrumana and of Man, in some striking
respects. The penis is pendulous, and the
proportions between the different organs are
not very dissimilar; but the testes do not
descend from the abdomen excepting during the
breeding season, when they are found on each
side of the anus, whilst the large epididymis is
seen just behind them, on each side of the
origin of the tail. The vestcule seminales are
of moderate size, and consist of two round
white sacs, which are perfectly simple, form-
ing each a single cavity with a secreting in-
ternal surface. They have a prostate gland,
which surrounds the whole circumference of
the urethra, and appears to be composed of
numerous small lobes. They have also Cow-
per’s glands. The penis is very similar to that
of the other more highly organized forms, the
Quadrumana and Man. It is of moderate
size, pendulous, and supported by ligaments,
as in the other cases. There is a small bone
of the penis. The muscular portion of the
urethra is rather long. The glans is in some
species enlarged by a small process or button
on each side; the urethra opens at the extreme
point.

The female organs offer nothing very par-
ticular. The vulva is round, and exhibits a
slight appearance of a clitoris near its edge;
the mouth of the uterus stands out into the
vagina. The uterus is two-horned and the
horns are very short.

There are but two teats, which are placed
on the breast. The additional ones said to
exist in the groin of the Rhinolophi are most
probably ordinary cutaneous glands, as Kuhl
could discover no trace of mammary glands
beneath them. They were first discovered by
Montagu in this country, and by Geoffroy in
France.

The Bats are among those animals in whom
we notice the remarkable phenomenon of Hy-
bernation, of which it is unnecessary to say
any thing here, as a distinct article is devoted
to the subject. (See HyBERNATION.)

For the Bibliography see that of MAMMALIA.
(T. Bell.)

CHYLIFEROUS SYSTEM (in Compa-
rative Anatomy) is that portion of the vascular
system of vertebrated animals which is destined _
to convey the nutritious part of the food, or the _
chyle, from the alimentary canal into the san=-
guiferous vessels. The function of these ve _
liferous vessels appears to be performed by the
veins in the invertebrated classes, where the
white colour of the blood causes them to re-
semble more closely the lacteals or chyliferous _
vessels of vertebrata. Several parts, however, —
of the invertebrated animals have been taken —

-

by anatomists for this lacteal system, as the —

Nike ATE ES ENC) A am al na
=_e* ‘ . _

CHYLIFEROUS SYSTEM.

nervous system of Mollusca by Poli, the biliary
tubuli of Insects by Sheldon, the mesenteric
vessels of Echinodermata by Monro, the radi-
ating prolongations from the stomach of Me-
duse by Carus. The chyle of vertebrata,
derived from the chyme of the digestive canal,
and much resembling the white blood of the
lower divisions of the Animal Kingdom, varies
in its physical properties and chemical com-
position in the different tribes of animals, and
in the same animal according to the kind of
food on which it subsists, (see CuyLE,) being
most allied to red blood in the highest animals
and those which subsist on the most nutritious
animal food, and being most remote from that
condition in the lowest fishes and the most
imperfect animals. The vessels which con-
vey, and still further elaborate, this fluid,. the
chyliferous system, like the other systems of

the body, present very different grades of de-

velopment in the different classes of vertebrata.

In fishes they consist of simple vessels in
which we cannot separate the two usual tunics ;
they are destitute of internal valves and me-
senteric glands, they form two strata of vessels
between the coats of the small intestine, and
they convey a limpid chyle to the receptaculum
chyli, from which it is sent by one or two
thoracic ducts to the branches of the su-
perior cava or the jugular veins. They com-
municate freely with the veins, they already
present numerous constrictions as rudimentary
valves, they present valvular orifices at their
entrances into the veins, and their numerous
convoluted plexuses supply the place of me-
senteric glands. -

.The chyliferous vessels are nearly in the
same condition of development in the amphi-
bia, where they form two layers on the parietes
of the alimentary, canal, are destitute of. con-
globate glands, form plexuses on the extended
mesentery, and terminate in two thoracic. ducts
which proceed forwards along the sides of the
vertebral column. (See Ampursia.)

_ In the class of. reptiles the lacteals pre-
sent a more advanced stage of formation,
chiefly in the development of the internal
valves in the trunks, and branches in all these
animals, and in the white milky condition of
their contents in the crocodilian family. (See
Repritia.) They are still without mesenteric
glands, their valves are less perfect than in
birds and quadrupeds, and the chyle is still
limpid and colourless in the serpents, lizards,
and tortoises. The coarse vegetable food of
the chelonia, and the great length of their small
intestine, give occasion for the numerous large
chyliferous vessels which cover their alimentary
canal and mesentery. The place of mesenteric
conglobate glands is yet supplied, as in the

_ inferior vertebrata, by numerous complicated

networks of lacteal vessels, formed in different
parts of their course; and, as in fishes, two or
more ducts are here observed. passing forwards

from a single wide receptaculum. The tho-

form numerous free anastomoses

seecnets.
with each other in their course forwards to the

. -neck, accompanying the left branch of the
_ aorta to the anterior part of the trunk, where

VOL. T.

these vessels.

601
they pour their contents into the jugular or
subclavian veins, or into the angle between
Before entering the veins these
ducts receive the lymphatic trunks, as in other
classes, from the head and arms. ‘The chyli-
ferous vessels of the chelonia coming from the
outer and inner layers spread on the small in-
testine, unite into considerable trunks, which
pass along the mesentery in close proximity to
the bloodvessels. The thoracic duct of the
tortoise surrounds and almost conceals the
trunk of the aorta by its numerous large anas-
tomosing branches.

The inferiority of the chyliferous system
of birds to that of quadrupeds is seen even’
in the properties of the chyle, which is still,
as in the lower tribes of vertebrata, a thin,
colourless, and limpid fluid. The lacteal ves-
sels are now, however, more obvious, and
more regular in their distribution, and are
spread in more crowded layers above the mu-
cous. and above the muscular coats of the in-
testine. They collect from the intestine and
form numerous anastomosing plexuses on the
mesentery, in place of the conglobate glands
of mammalia, and then proceed, with the lym-
phatics, to the receptaculum, which sends for-
ward two thoracic ducts to terminate, on each
side of the neck, at. the junction of the sub-
clavian with the jugular veins. (See Avzs.)
The coats of the lacteals are still very thin and
distensible in birds; their valves, which are
more abundant on the trunks and branches
than in reptiles, are still so incomplete as to
allow injections to pass easily against their
course, and although. conglobate glands are
not yet developed on the chyliferous system,
they are already perceptible on the lymphatics,
especially in the neck.

The chyliferous system of the mammalia,
though more developed than that of all the
inferior classes, is. still imperfect as a hy-
draulic apparatus when compared with the
sanguiferous system. The lacteal and lym-
phatic systems may still be regarded as mere
appendices of the venous, performing the func-
tions which are assigned to veins in the inver-
tebrated classes, and serving as inlets to the
materials which renovate the blood. No pul-
sating sacs have yet been detected in the lym-
phatic system of quadrupeds, nor any distinct
motion in the lacteals, the receptaculum, or
the thoracic duct. The chyliferous system of
this class presents a superiority of develop-
ment in the almost sanguineous characters of
the chyle, in the more perfect structure of the
vessels and their valves, in the development
of the conglobate mesenteric glands, in the
frequent unity or concentration of the thoracic
duct, and in the more isolated condition of this
system from the sanguiferous. . The mesenteric
glands are chiefly confined to the mesentery of
the small intestine ;. they are generally placed
apart from each other; sometimes they are
united into a pancreas Asellii ; they are firm in
texture, highly vascular, and composed of con-.
voluted lacteals, like more concentrated forms
of the plexuses of the lower vertebrata.

(R. E. Grant.)
2h

602

CHYLIFEROUS SYSTEM (Human Ana-
tomy). See Eacreat.

CICATRIX. (Fr. Cicatrice ; Germ. Narbe.)
When from accident or disease a portion of
any organ in the body has been destroyed,
‘a process is set up by Nature for the repair
of the breach, a new structure is generated,
which possesses many properties of conside-
rable interest and importance both in a phy-
siological and a pathological view. The new
formation constitutes what is termed a cicatrix,
and the process by which it is completed, the
process of cicatrization. We shall in this
article give a general view both of the mode of
of repair and of the product when completed.

The restorative process, when a part of the
skin has been destroyed, is extremely in-
teresting. The first stage varies according
as the part is removed at once, as by exci-
sion, or secondarily, as by sloughing. The
immediate effect of removing a portion of skin
is, that the surrounding integument, by its
inherent elasticity, retracts, and to a certain
extent, enlarges the breach made by the wound.
In a short time after the infliction of the injury
inflammation and suppuration take place.
As the next -step, fibrine is effused, which very
shortly becoming organized, constitutes those
red, soft, roundish elevations known by the
name of granulations. As these form, a con-
traction of them occurs, by which the edges

of the sore,which had at first retracted, are now .

brought back again towards their original si-
tuation.

John Hunter informs us that this contracting
tendency in the granulations is in some degree
proportioned to the general healing disposition
of the sore, and the looseness of the parts on
which the granulations are formed, for when
there is not a tendency to skin, the granulations
do not so readily contract.* The contraction
continues till the whole is healed over, but its
greatest effect is at the beginning; one cause

of which is that the resistance to it from the -

surrounding parts is then least.

While this is going on within the circum-
ference of the sore, and immediately pre-
ceding the commencement of actual cicatri-
zation, the surrounding old skin, close to the
granulations, becomes smooth and rounded
with a whitish cast, as if covered with some-
thing white, and the nearer to the cicatrizing
edge, the more white it is. At this moment
the process of cicatrization is actually begin-
ning, and the new cuticle may now be ob-
served to be spreading from the circumference
of the sore towards the centre, not uniformly,
but creeping irregularly over the granulations,
or rather formed irregularly from them, but
always, in recent sores, spreading in a con-
tinnous surface from the circumference. In
large and old ulcers, however, in which the
edges of the surrounding skin have but little
tendency to contract, or the cellular membrane
underneath to yield, the old skin also having
but little disposition to skinning in itself, the

* On the Blood, 8vo edit.

‘In question.

CICATRIX.

nearest granulations do not receive from it a
cicatrizing tendency. In such cases new skin
forms in different parts of the ulcer, standing
upon the surface of the granulations like little
islands. The rapidity with which the skinning
process takes place in this stage is but an un-
certain criterion whereby to judge of the time
that will be occupied in the cure. Generally
speaking, the latter stages of the process are
much slower than the earlier, particularly when
the breach of surface has been large.

And here a question arises: is the new skin
that is formed the result of an altered state of
the granulations themselves, or is it an entirely
new product from them? Bichat inclined to
the former opinion, holding that the granu-
lations having discharged their fluid contents,
collapsed, and uniting one to another, became
converted into the uniform smooth membrane
Hunter, on the contrary, con-
sidered the new cutis as a new product, the
secretion of the granulations. Our own ob-
servations lead us to adopt the opinion of
Bichat. It seems that, as soon as the surface
of a granulation is covered over with epidermis,
which is often the case before the least shrink-
ing or collapse of the granulation occurs, then
the secreting orifices of those numerous vessels
of the granulation which had hitherto been
eae out pus are now sealed up, and

aving no longer any use, the same change
takes place which occurs in other parts of
the system similarly circumstanced: an or-
gan no longer in use shrinks and the fluid
parts become absorbed, and the elevated soft
and spongy granulations shrink into the thin
and somewhat dense fibrous structure of the
cicatrix. We cannot agree with the opinion
of M. Dupuytren, that the chorion is formed
first, and the epidermis added subsequently,
since we have often detected the epidermis
creeping over granulations so little altered in
appearance that its presence could only be dis-
covered by placing the part in such a light
that its dry shining surface could be distin-
guished from the soft, villous appearance of the
neighbouring granulations. The process of
contraction, we believe, generally, if not always,
does not precede but follows the formation of
the cuticle, and consequently the cutis formed
by this contraction does in the order of time
follow the cuticle. The reason of this we can-
not explain, but of the fact we cannot doubt;
and this fact accounts for the very slow
formation of the cuticle in the first healing
of an ulcer where that membrane is formed from _
the granulations. The organization of these
bodies may be said to be much inferior to —
that of the cutis when completed; hence, when —
the cuticle of a cicatrix is abraded, it is ily
formed again, because it has now a more pel
organ to secrete it. oe

As the new cuticle covers the granulations,
then, these two striking changes immediatel;
take place in their state; the secretion of pt
is stopped, the surface becoming dry, and th
process of shrinking or contraction be
which we shall find to continue for a co
rable period after the whole sore is appare

CICATRIX. 603

healed. The contractile action takes place in
every direction, producing that depression of
the cicatrix which is observed to follow the
spreading of the cuticle over the granulations.

us those parts which were soft and spongy
now acquire firmness, and form a condensed
layer, which occupies the position, and per-
forms some of the functions of the original
cutis which had been destroyed.

It is an interesting question, why the cuticle
in covering an ulcer, though evidently formed
from the granulations, is arising not over the
whole surface of the ulcer at once, as it is

’ when abraded from the healthy skin, but creeps

from the circumference towards the centre, in
a slow, progressive manner? It seems that a
greater perfection of organization is necessary
for the production of cuticle than for the for-
mation of granulations capable of secreting
pus. If we examine the vascular structure of
these newly formed parts, we find that the
bloodvessels apparent on the granulations are
few and very irregular in their course, and
often in figure also, having an appearance re-
sembling a varicose or unequally dilated state ;
this we take to be an indication of a feeble
and incomplete state of organization. On the
contrary, the vessels in the immediate vicinity
of the new skin, are more regular in form and
direction, and may often be seen running on-
wards through the neighbouring granulations
towards the centre of the sore, having a good
deal the appearance of the vessels of the in-

flamed cornea; and where this is not remark-

ably apparent, the granulations in the imme-
diate neighbourhood of the parts in which the

skinning process is going on are more vascular

than the internal ones. Our observations
would lead us to believe that this more perfect
system of circulation commences by an anasto-
mosis newly set up from the vessels of the
edge of the healthy skin first, and by the action
of these newly formed vessels the cuticle is
secreted. From these, others are still sent on
over the surface of the sore, or immediately

under it, and thus by progressive steps the

necessary degree of perfection of structure is

acquired, and is immediately followed in its

oegare by the development of the cuticle.
is, be it remembered, is still a different state
of the granulations from the contracted un-
secreting layer which constitutes the new cho-
rion. If this description of the process is
consistent with Nature, it is reasonable to sup-

that the new vessels shooting from the
edges of the healthy skin would be more per-
fect, and more equal to the task required than
those which would pass through the granu-
lations from the subjacent cellular tissue; and

In the same way we may suppose that one part

being in the before-mentioned manner com-
pot, is better fitted to send on new vessels
the organization of the next portion of
ulations than the granulations themselves.

tis moreover to be expected that the power
of organizing its neighbouring parts must be
Superior in the healthy skin to that of any
newly formed structure, and that this power
will in an extensive sore gradually diminish

as the distance from the healthy parts in-
creases ; and this accords with the well-known
fact that the cicatrization goes on much more
slowly in the latter stages of healing than at
the commencement

Thus the external process of skinning is
completed, but the internal changes are not
yet finished. A slow but remarkable change
is going on for a considerable time longer, by
which the appearance and structure of the
cicatrix becomes modified. Froma red colour
it becomes gradually paler, till it is almost
white; this at least is the general rule, though
under circumstances, to be presently mentioned,
the result is different. The cicatrix also conti-
nues to contract in all its dimensions, thus not
only diminishing in extent, but sinking below
the level of the surrounding skin, and becoming
more dense and thin and more perfect in its
organization, till it has assumed the appearance
and character which it will retain through the
rest of life.

It is this power of contraction resident in the
new chorion of the cicatrix, that produces
those bridles which are such frequent causes of
deformity after the healing of extensive burns.
In these cases there does not seem any neces-
sity to have recourse to any peculiarity of
hypothesis in explaining the great degree of
shrinking that so commonly occurs. On the
contrary, we conceive that the phenomena at-
tending the healing up of burns are to be ac-
counted for by means of the usually recognized
causes of the shrinking in the cicatrices of
wounds in general.

We have now described the process of re-
pair in wounds in the skin, with loss of the
entire substance of the cutis. When the de-
struction has been more superficial, the process
of restoration is more rapid, and the result
more perfect, inasmuch as the part upon which
the burden of repair devolves, is the inner
layers of the original cutis, a part much more
highly organized and more equal to the task
than the cellular tissue.* In wounds which
are united by the first intention, the stage of
suppuration does not take place. The sub-
stance which would have formed suppurating
granulations here becomes an immediate means
of union, and the only portion of new skin
formed is.in the mere line where the divided
edges met, a line always visible by the white
colour before mentioned.

In the healing of ulcers in any of the mucous
membranes, the process would appear to go on
much in the same way as on the skin. Granu-
lations shoot up from the bottom of the ulcer;
the surrounding healthy membrane is drawn
inwards by their contractile power, and the
edges of the ulcer are turned in and become
continuous with the new membrane, which at
length covers the ulcer. When the destructive
process has merely gone through the mucous
membrane, the granulations shoot from the mus-
cular coat, and the contraction is of course ex-
ercised only upon the surrounding mucous coat;
but when the muscular tunic is destroyed, the

* See Hunter on the Bload, 8vo edit. p. 274,
2R2

i

604

granulations grow from the bottom of the wound,
that is, from the cellular tissue in contact with
_the peritoneum ; but the contraction of the sur-
rounding parts now diminishes the circumfe-
rence of the ulcer very considerably by puck-
ering up this thin layer of membrane, so as to
give it externally an appearance as if a small
portion of the intestine had been taken up by
the forceps and tied with a ligature on the in-
side.* hen the process of repair is com-
pleted, a fine web-like production from the
edges of the ulcer overspreads its base, and
forms fine wrinkles converging towards its
centre. This production is destitute of villi,
and slightly depressed. ‘When the ravages of
the disease have been very extensive, the cica-
trix is covered by puckered cellular tissue,
formed of white thread-like filaments, crossing
each other in all directions, and leaving pitted
interstices.t| When the ulcer was small, the
cicatrix has sometimes a considerable resem-
blance to the scar of small-pox.t{

That cicatrization takes place in the lungs
after tuberculous excavations, the observations
of Laennec§ and Andral|| among others, have
put beyond a doubt; and since these patholo-
gists have made public their observations of
the fact, and pointed out the signs by which it
may be known, most observers have borne tes-
timony to the accuracy of their statements.
According to Laennec there are three ways by
which this desirable object is accomplished ;
one, by the walls of the cavity becoming lined
with a membrane of a semicartilaginous struc-
ture and smooth polished surface, which
seems often continuous with the lining mem-
brane of those bronchial ramifications which
open abruptly into the cavity. This state of
the restorative process constitutes a sort of in-
ternal cicatrix, analogous to a fistula, and js in
many cases not more injurious to health than
the species of morbid affection just mentioned.
The second mode of cicatrization consists in
the obliteration of the morbid cavity by adhe-
sion of its sides. In the complete state they
exhibit, when cut into, a band of condensed cel-
lular substance or of fibro-cartilaginous struc-
ture. The bronchial tubes which run towards
this structure are obliterated as they reach it,
and there is generally an unusual! quantity of
the peculiar black matter of the lungs in the
paits bordering upon the cicatrix ; and where
this is the case, the structure of the lungs is
more flabby and less crepitous than natural.
These internal cicatrizations are indicated on
the surface of the lung by a depression of the
pleura, the depth of which corresponds with

* Dr. Latham on the Disease of the General
Penitentiary, p. 51.

+ Dr. Hope’s illustrations of Morbid Anatomy,
vol. i. p. 203. See also Billard’s Recherches
d’Anat. Pathol. p. 534.

¢ Bright’s Medical Reports, vol. i. p. 182, where
are some very interesting illustrations of this por-
tion of pathological anatomy. See also on this
subject a valuable paper by M. Troillet in the Jour-
nal Gén. de Médecine. Reported in the Med. Chir.
Rev. vol. v. p. 192. ;

On Mediate Auscultation, translation by Dr.
Forbes, 2d edit. p. 300. “a
|| Clinique Médicale, tom. iii. p. 382.

CICATRIX.

the size of the previous excavation, and is
sometimes so deep as to form a large over-
lapping oo of the neighbouring sound
parts. Here we have another instance of the
same contractile tendency in newly formed
structures, which is so striking in cicatrizations
of the skin; a tendency resulting from the gene- _
ral law by which the labour of restoration is, as
much as possible, spared to the animal system.

The third species of cicatrix in the lungs is
that formed by the fibro-cartilaginous walls in-
creasing in thickness till they fill up the cavity, .
thus leaving a blueish or greyish white mass, in |
which large bronchi terminate abruptly as in
the preceding case. Cicatrices of the two last
kinds are not uncommon.*

In the healing of common abscesses, whether
in the subcutaneous cellular tissue or in the
more deep-seated parts, the mode of cicatriza-
tion is much the same as in the second species 5
just described. As the fluid contents are re-
moved by evacuation, the cavity of the abscess
is diminished in extent partly by the contrac-
tion of the surrounding tissue and partly by the
granulations arising from the sides of the ca-
vity, and as the opposite sides are thus brought
in contact they adhere, and at length leave a
fibrous cicatrix, whitish and more dense than
the surrounding cellular tissue. It is remark-
able that few or no abscesses granulate till they
are exposed, and that after they are opened
there is one surface that is more disposed to
granulate than the others, which is the surface
next the centre of the body in which the sup-
puration took place. The surface next the |
skin hardly ever granulates, but on the contrary
has an ulcerative tendency The proximate |
cause of this remarkable difference is not evi-
dent, but the utility of it in the healing of the
abscess is clear and striking. 5

We have now considered the processes by
which nature repairs the breach in the healthy
structure ; let us in conclusion shortly examine
the characters which mark the cicatrix when
completed. This new formation, though in
many points it resembles and fulfils the func-
tions of the old and perfect skin, yet differs
from it in many material respects.

1. It occupies, as we have stated, a smaller
space, having by its contraction drawn the
surrounding skin inwards, and thus, by the
wise economy of nature, diminished the surface
requiring new skin tocoverit. Thisisof course
most strikingly seen in those parts where the
cellular texture is loose and yielding, as in the _
scrotum, where a large loss of skin is often
healed with only a very small cicatrix. On the —
contrary, parts that cannot so yield are heale
with a proportionately large cicatrix, as
wounds of the scalp, &c. 2. The texture of
the cicatrix is frequently harder and thieke
than the natural skin. This circumstance var
considerably, but we believe this variation v
be found to bear a pretty exact relation to t
degree of contraction, to the length of |
occupied in the cure, and to the iritation
_* See Hope’s Illustrations of Morbid An
vol... pi 34," = Sie ine = —
+ Hunter on the Blood, p. 593.

i
4

4
a
a
¥

— ae

CICATRIX.

which the ulcer was subjected in the process of
healing. When these have been considerable,
the hardness is correspondingly great, while, if
the cure has been expeditious and the part
been kept extended and irritation avoided, the
cicatrix remains soft, thin, and pliable, a point
of great importance in practice as applied to
the. healing of burns. E. The colour of the
new skin is different from the natural parts.
This arises from the want of rete mucosum,
which is not regenerated till long after the
other tissues, and sometimes not at all. For
this reason a cicatrix in a Black is as white as
that in an European; but after a considerable
lapse of time, this structure is sometimes
formed anew, and in some instances becomes
even of a darker colour than before. 4. ‘lhe
surface is perfectly dry from the want of ex-
halent pores, which are never found to be
restored even in the oldest cicatrices. Indeed,
in cases where the chorion has not been de-
stroyed through its entire thickness, the luss
of substance reaching only through its outer
layers, these pores are generally obliterated,
and the important exhalent function of the
skin is annihilated ; and even when the injury
has extended only through the external vas-
cular structure of the skin, as is the case in the
healing of a blister which has been long in-
flamed, we have observed a drier state of the
parts, and more polished than the surrounding
skin which had not been injured. From this pe-
culiarity in the cicatrix, when the whole body is
bathed in sweat these parts are dry and po-
lished. This state of dryness, however, partly
results from another anatomical deficiency,
ely. of the perspiratory glands, which are

stroyed in cases where the entire integument
has been injured, and these are of course never
regenerated. 5. The new tissue contains no
hairs, and if, after superficial wounds, a few
scattered hairs appear on the surface, they are
feeble and white. 6. After the healing of a
large ulcer of long standing, the new surface
is sometimes much lower than the surround-
ing skin. Nature seems, in these cases, to
have exhausted her energies in the long en-
deavour to heal the ulcer, and the granulations
never rise to the level of the surrounding skin,
as in recent cases. The new cuticle there-
fore commences upon those granulations which
shoot from the elevated edges of the ulcer, and
the cicatrizing process is thus led as it were
into the hollow of the ulcer, and spreads along
its surface, completing the cicatrix in an exca-
vated form. 7. The elasticity of the cellular
tissue under the new chorion is less than that
of the ordinary cellular web; nor does it allow
of distension to the same degree. This is
seen in edema and emphysema, where this
part will often remain depressed while the sur-

rounding parts are raised and distended ; it is

also seen in the impediments which large cica-
trices prove to the movements of the joints.
he same circumstance perhaps also gives a

reaso ason for there being no fat contained in these

ee This want of extensibility seems to be
but one consequence of the law which regu-

_ lates the products of inflammatory action. The

elastic power is materially diminished in the

605

natural cellular tissue by inflammation, a de-
gree of stiffness and difficulty of movement
remaining for a long time after; and as the
tissue of a cicatrix is, ab initio. the product of
inflammatory action, it is to be expected that it
should shew the same effects.

How far are the vascular and nervous func-
tions of the lost part restored in the cicatrix?
It is probable that the new structure receives
nerves, but in small number. Of those senses
which can be implicated in the destructive
process of ulceration, that of touch alone seems
to be restored. This is so ina marked though
still imperfect degree, the ‘sensation in these
parts being somewhat of that dull kind expe-
rienced after paralysis.

On the temperature of the cicatrix we have
not made sufficient observations to generalize,
but we have found that the actual temperature
of the bridle from a burn, while it retains its
hardness, is several degrees above that of the
healthy skin, while the power of retaining its
temperature, or of resisting the extremes of
heat and cold, is much inferior in the cicatrix to
that which the healthy skin possesses, although
the actual temperature, wader ordinary circum-
stances, is the same as the surrounding skin.
Almost every traveller to the Poles or to the
Tropics mentions the liability of old ulcers that
had been healed, to announce the extremes of
temperature by pain and inflammation.

The bloodvessels of the new structure are at
first numerous, as indicated by the redness and
the readiness with which it. bleeds, but after-
wards they diminish much in size and number,
so that, in an old cicatrix, it is often impos-
sible to force an injection into them. M. Du-
puytren tells us that in scars upon the face the
greatest heat from exercise, or the influence of
the mind in producing blushing, leaves this
part uncoloured amid the surrounding redness.*
Bichat assures us that even the new epidermis
itself is overrun with bloodvessels.t We have
certainly never been able to discover the least
trace of vascularity in it, nor have we found
that sensibility in this part which he describes.
It seems to be a matter of doubt at present how
far the function of secretion exists in the new
production. Dr. Bright seems to believe in its
restoration, since he says that the scar in one of
his observations appeared to be covered with a
true mucous membrane ; but it is right to state
that the proof he gives of this is rather equi-
vocal, namely, that the surface was quite con-
tinuous with the membrane lining the rest of
the canal; “ indeed,” he adds; “ when inspect-
ing the ulcer in the process of healing, we per-
ceive the vessels of the mucous membrane
running over the surface to be repaired.”{ M.
Troillet mentions in round terms that the cica-
trix had the thickness, consistence, and ap-
pearance of mucous membrane ;§ but neither
he nor Dr. Bright says any thing in particular
as to the villous structure, which we conceive to
be an essential characteristic of some forms of

* Lecons de Clinique Chir. tom. ii. p. 47.
+ General Anatomy, Trans]. vol. ii, p. 899.
¢ Med. Reports, vol. i. p. 182.

¥ Med. Chir. Rev. vol. v. p. 194.

C06
mucous membranes.* Dr. Hope’s and M. Bil-
lard’s cases were destitute of villi, and the
latter expresses a doubt whether it ever takes
place. Our own observations decidedly incline
us to the same opinion.

Like all adventitious organic products, cica-
trices are very readily irritated and are de-
stroyed by ulceration with amazing rapidity.
A few days and even a few hours are sometimes
sufficient to undo the restorative labours of
many months; but this destruction is often su-
perficial, and then the after-healing is as rapid
as the previous ulceration.

M. Dupuytrent informs us that the cicatrix
resulting from an entire destruction of the skin
is not liable to be affected by many exanthe-
matous diseases, such as scarlet fever, measles,
and small-pox; it remains pale in the midst of
the inflammation and eruption which covers
the neighbouring parts. ‘The contrary takes
place only in superficial cicatrices, under which
some layers of the original cutis exist, and
which participate in the properties as well as
in the inflammatory tendencies of the rest of
the skin.

In conclusion we may state, that it appears,
from the previous considerations, that in the
repairing of the injuries in question, beautiful
as is the process and useful as are the results,
yet nature’s great object does not consist so
much in an endeavour to restore the lost struc-
ture in all its functions and perfections of
organization, as merely to produce a covering
for those parts which remain uninjured, to act
as a defence to them from external irritations
and injuries, and possessed therefore only of
such a degree of vitality and of such properties
of structure as shall be sufficient for its own

preservation and repair.
(A. T. S. Dodd.)

CILIA,{ (in anatomy, Fr. Cils; Germ.
Wimperhaare.) This term is used to desig-
nate a peculiar sort of moving organs, re-
sembling small hairs, which are visible with
the microscope in many animals. These organs
are found on parts of the body which are
habitually in contact with water or other more
or less fluid matters, and produce motion in
these fluids, impelling them along the surface
of the parts. ‘The currents or other motions
thus produced serve various purposes in the
economy of the animals in which they occur.
In other circumstances the cilia serve as
organs of locomotion, some aquatic animals
propelling themselves through the water by
their means.

Cilia have now been ascertained to exist in
a great many invertebrated and in all verte-
brated animals, except Fishes ;§ having been
very recently discovered by Purkinje and Va-
lentin on the respiratory and uterine mucous

membranes of Mammalia, Birds, and Reptiles.

The terms “ vibratory motion” and “ ciliary
motion” have been employed to express the

* Med. Chir. Rev. vol. x. p. 324.

+ Op. cit. tome ii. p. 48.

¢ For another signification of this term, see the
articles EYE and LACHRYMAL APPARATUS.

§ Fishes are no longer an exception; see note
at page 632,

CILIA.

appearance produced by the moving cilia ;
fe latter +d are preferred, but it is used to
express the whole phenomenon as well as the
mere motion of the cilia. |

A considerable space has been allotted to
the present article, more perhaps than its re-
lative importance may seem to demand, chiefly —
for the reason that, with one exception, no
attempt has been hitherto made to collect and
describe under appropriate heads, the facts
known on the subject. The exception alluded
to isa work by Purkinje and Valentin,* which
appeared while this article was in progress, and
which contains not only an account of their own
discovery, but a history of all preceding obser-
vations. But the manner of treating the sub-
ject in the work alluded to is for the most part
so different from that which is here followed,
that its publication has not seemed to warrant
any material abridgement of the following
article, which, on the contrary, it has increased
by affording much new and important matter,
as will be acknowledged in its proper place.
Another ground on which indulgence may be
claimed for details which are, perhaps, greater
than may seem commensurate with the impor-
tance of the subject, is that many of the facts
are here described for the first time, and it was
felt desirable to state them in their full extent,
which could not be done intelligibly without
considerable length of description.

The article is divided into two parts; the
first comprehends the particular facts, or an
account of the phenomena as they occur in the
different tribes of animals considered in Zoo-
logical order, with the history of their dis-
covery; the second part consists of general
deductions from the first, and also treats of the
structure and mode of action of the cilia in
general. This method has been adopted as
appearing on the whole best suited to the pre-
sent state of knowledge on the subject.

PART I.
1. Infusoria.— Cilia exist very extensively
in the different tribes of Infusory Animalcules;
indeed they constitute the principal organs of
motion in these small animals. When a drop
of water containing Infusoria is brought under
the microscope, these creatures are seen swim-
ming rapidly through it in various directions ;
and as they move along, small particles of
foreign matter which happen to lie near their
path are thrown into agitation, obviously in-
dicating the existence of currents in the neigh-
bouring water. When the animals remain
steady in one place, these currents become
much more distinct, setting in particular di- —
rections, and causing the small particles to run
in a stream to and from the animal. If the
magnifying power be sufficiently strong, small
transparent filaments will be distinguished,
projecting from the surface of the animalcules
and moving in avery rapid manner. Thes¢
are the cilia; they serve like fins or paddle:
to carry on the animal in its progression throug
the water, and when it is stationary, they im
the water in a current along the surface,

* De
Wratisl.

Besnemegs motus vibratorii, &e.

CILIA. v07

is beset with them. They may be often
most distinctly seen when their motion be-
comes ra or impeded, as is the case
when the water round the animal is diminished
by evaporation to such a degree as not to afford
sco r their full and rapid play.

he cilia of the Infusoria in their arrange-
ment are either separate and independent, or
combined, forming in the latter case the rota-
tory or wheel-like organs of the rotiferous tribes
of animalcules.

In the first or simple form, which exists in
the Polygastric Infusoria (fig. 289), the cilia
are usually set round the
mouth or spread over the
body generally, in which
case they are often disposed
in regular rows. Their struc-
ture has been carefully in-
vestigated by Professor Ehren-
berg, who states that each is
furnished with a bulb at the
root, to which minute muscles
are attached. A slight degree
of rotation communicated to ‘yin!
the bulb causes a much more ="
extensive motion in the rest
of the organ, which in its re- Leucophrys
volution describes a cone. patula.
From time to time the animal sets its cilia in
motion, and then, if its body be free, the cilia,
acting like fins or oars, move it onwards through
the water, serving in this case as organs of lo-
comotion. If the body is fixed, the cilia com-
municate an impulse to the surrounding water
and excite a current init. This may always
be made evident by mixing with the water

Fig. 289.

GE

*
iy

iZ

x
FFLE

=
Zz,

L
IFES pit

(772 un tle
AN

CPFF.

ya

Sree
LZ

A

a,
—

some colouring matter, the particles of which

are hurried along by the current. Many of
these particles are conveyed towards the mouth,
where some are swallowed and the rest thrown
back, the cilia in this case serving the animal
as a means of seizing its food.

In their combined form the cilia constitute
the singular and well-known rotatory or wheel-
like organs of the Rotiferous Infusoria. These
are formed of one or more circles of cilia,

laced on the fore part of the animal, as in

hilodina (fig. 290), in which the organ is
double, consisting of two cir-
cles of cilia set on two short
processes, one on each side of
the mouth. This apparatus
can be retracted or pushed
out at the will of the ani-
mal. When in motion, the
circles of cilia have the ap-
pearance of toothed wheels
turned round on their axes,
first in one direction and then
in the opposite. Various ex-
planations of this apparent
revolution have been given.
According to Ehrenberg it is Philodina
an optical deception, which erythropthalma.
he thus explains: the individual cilia com-
posing the rotatory organ move in the same
Manner as the separate cilia above men-
tioned, that is, they each revolve in such a

Fig. 290.

way as to circumscribe a conical space. When
viewed sideways, in performing this revolution
they must necessarily pass at one moment a
little nearer, at another a little more distant
from the eye, or, in other words, become alter-
nately more and less distinct to the view at
short intervals; and this alternation occurring
over the whole circle gives rise to a seeming
change of place in every part of it, and a con-
sequent appearance of rotation. Perhaps it
would be an equally satisfactory and a more
simple explanation to consider the appearance
as occasioned by an undulatory motion of the
cilia, such as that produced by the wind ina
field of corn; the undulations following one
another in every part of the circle would give
the appearance of rotation. Such a waving
motion of the cilia undoubtedly occurs in
other animals. The Rotifera set in motion or
retract their ciliary organs apparently by a

- voluntary act; they use them for similar pur-

poses as other Infusoria use their simple cilia ;
when the body is free, the rotatory organ pro-
pels it through the water; at other times the
animal fixes itself by its tail, and setting in
motion its wheels, produces currents in the
water, by means of which it seizes its food.
These currents in most of the Rotifera have a
determinate and regular direction.

The cilia of the Infusoria, then, serve as
organs of locomotion; and in the greater
number of species they are the only visible
organs for this purpose; indeed it is not im-
probable that they may exist in others in
which from their smallness they have hitherto
eluded observation; as in such cases cur-
rents are observed which are most probably
produced by invisible cilia. Secondly, the
cilia are employed by the animals in catching
their food. Thirdly, it is extremely probable
that, by bringing successive portions of water
into contact with the surface of the animal,
they serve also for respiration.

Soon after the invention of the microscope,
the animalcula of infusions became a favourite
subject for its employment, and the cilia and
the motions which they produced did not
escape the notice of the earlier microscopic
observers. Leeuwenhoek observed them dis-
tinctly and recognised their use, and probably
he was the first that did so. He repeatedly
makes mention of them in his writings. At
one place* he describes them in an animalcule,
smhich seems to have been the volvor, as short
slender organs projecting a little from the body,
by means of which the animal produced a re-
volving motion and moved onwards. Again,t
in speaking of the animalcules which he ob-
tained from an infusion of pepper, he states
that these animals produced a great commotion
in the water by means of divers organs placed
on the fore part of the head, which organs also
the animals used in swimming. “ In this
way,” says he, “ they occasioned such a cir-
cular eddy in the water that not only several

* Continuatio Arcanorum Nature, 1719, p. 382,
Epist. 144. :

+ Continuatio Epistolarnm, 1715, p. 95, Epist.
17, Oct. 1687.

608

small bodies floating in the water were moved
in a cireular manner, but even many’ very
minute animalcules, though able to swim
vigorously, when they approached the larger
animalcules, were whiled about for some time
in a circular manner.” In announcing ‘his
discovery of the wheel animal,* he describes
its rotatory apparatus as two projectiig discs
set round with very slender elongated organs.
* Imagine,” says he, “two wheels set’ round
with points of needles, and moved very swiftly
round from west by the south to the éast.” He
adds that he cannot comprehend how such
motion takes place in a living body. Lastly,
in describing a small animal which he found
adhering to the water-lentil, (probably'a species
of vorticella,) and speaking of the currents
which it excites, and by which it attracts its
food, he adds the following reflection :+ “ More-
over it is necessary that these animals, and in
general all such as are fixed and cannot change
their place, should be provided with an appa-
ratus for stirring up motion in the water, by
which motion they obtain any matters that float
in the water, for their nourishment'and growth
and for covering their bodies.”

Baker,{ next to Leeuwenhoek, takes notice
of the cilia of animalcules. He observed them
in many species, and named them fins, or feet,
and sometimes fibrille. He distinctly recog-
nised the currents produced by them, and in-
ferred the existence of cilia as the cause of
visible currents in cases where the cilia them-
selves could not be seen.§ In particular, he
bestowed much pains in investigating the eco-
nomy of the wheel animal previously disco-
vered by Leeuwenhoek, and addressed a letter
‘to the Royal Society on the subject, in 1744.||
He there describes its rotatory apparatus as
“a couple of semicircular instruments round
the edges of which many little fibrille move
themselves very briskly, sometimes with a kind
of rotation, and sometimes in a trembling or
vibrating manner,” 4/———“ by this means a cur-
rent of water is brought from a great distance
to the very mouth of the creature, which thereby
is supplied with many little animalcules and va-
rious particles of matter.” ** Healso states that the
wheels are instruments of locomotion by which
the creature swims.tt Baker drew a distinc-
tion between the rotatory and vibratory motions
of the cilia, these organs being moved in some
animals in the one way, in some in the other,
while in others they seemed capable of being
used in both ways.j{{ It appears that he was
aware of the true structure of the so-called
wheels, and though he often speaks of their

* Continuatio Arcanorum Nature, 1719, p. 386,
Epist. 144.

+ Epistole Physiologice, 1719, p. 66. Epist. 7.

¢t 1 cite his work entitled ‘* Of Microscopes,
and the Discoveries made thereby,’”’ London, 1785,
although his observations were previously related
in separate memoirs of a much earlier date.
§ Of Microscopes, vol. i: p. 71, p. 80.

l Reprinted in op. cit. ii, p. 267.

| P. 271.

** P. 273.

tt P. 284.

$} P. 292.

CILIA.

the reality of the aj

describes them as small filaments or’points
‘agitated with a vibratory or oscillating motion.

being turned round, he was still doubtful of
parent rotation,” =

~ Spallanzani, in his curious and interestin

reséarches’ on the production’ atid econom

thé Infusoria, made observations similar to those

of Baker on the cilia and their motions.” He

He conceived them to be organs of locomotion
which the animals used in’ swimming,* and
that they also served to excite a vortex or Cur-
rent by means of which food was brought to
the mouth. “ The oscillating filaments cause
the vortex; the vortex draws the floating par-
ticles into the aperture or mouth of the animal-
cule, and the latter chooses for its aliment the
most delicate, or at least those which suit*it
best.”+ He afterwards describes the’ ciliary
apparatus of the vorticella in a similar man-
ner.$ In the account of his singular experi-
ments on the apparent resuscitation of the
Rotifer, he describes its wheel organs as two
circles of filaments, exactly like the vibrating
filaments of other Infusoria, which by their
continued motion give rise to the appearance
of two moving wheels; but he distinctly states
that the rotation is only apparent, not real.
These organs, he adds, serve the same purposes
as the’simple cilia.§ at ay
Needham,|| about the same time as Spallan-
zani, correctly observed the cilia, and recog-
nized their uses. Saussure] observed the cur-
rents, but did not perceive the cilia. © Pallas,**
in his systematic work on Zoophytes, describes
the eddies or currents produced by certain Roti-
fera, and notices their cilia, but far less clearly
than his predecessors. Wrisberg+t observed the
currents and eddies produced by the vorticellz; d
at least he saw smaller Infusoria and particles of
floating matter hurried on towards their mouths, ~~
but he seems not to have perceived the cilia.
Otto Frederick Miiller,{{ in his systematic
work on the Infusoria, described the appear-
ance and arrangement of the cilia in each
species, and represented them in figures. He
named them cilia and pili, and ascribed to
their action the currents and vortices which the
Infusoria excite. But while he assigns to them
the office of locomotive organs, he denies that
they are employed in seizing food; for, what
is singular, in his long-continued and elaborate
inquiries into the economy of these animals,
he could never perceive that foreign matters
drawn into the mouth were retained there as
nourishment, but believed that they were ~
always again thrown out. In this, however, —
he was undoubtedly mistaken. oe

* Opuscules de Physique, tom. i. p. 180.

+ P. 183. a “aT ee he

t P. 199. a
Tom. ii. p. 227. a

| Spallanzani, Nouvelles Recherches sur I
Decouvertes Microscopiques, &c. 1769, p. 161. —
] See Letter by Bonnet, in Spallanzani Opu
cules, tom. i. p. 176. © ht
** Elenchus Zoophytorum, 1766. a
++ Observationum de Animalculis Infusoriis sa
tura, 1765, p. 52, p. 63. :
¢t Vermium Terrestrium et Fluviatiliur
toria, 1773, and Animalcula Infusor.a, 1786

CILIA.

- Gleichen,* in 1778, described the currents
produced by the vorticelle. In an earlier
work he ascribed an agitation of small bodies,
which he had observed in the neighbour-
hood of one of the Infusoria, to an electric

or magnetic force, not having perceived the
Cilia tarsi Fe

Fontana{ described the rotatory apparatus

of the Rotifer and its use ; he conceived that its
apparent rotation was produced by the succes-
sive elevation and depression of the cilia which
encircle it.
_ Of the more recent writers who have inves-
tigated or described these phenomena in the
Infusoria, I may mention Dutrochet,§ Gruit-
huisen,|| Agardh,{/ Raspail,** and Ehren-
berg.t+ Raspail denies the existence of cilia,
attributing their appearance to an optical de-
ception, an opinion which is undoubtedly
erroneous. Ehrenberg, who, of all recent ob-
servers, has contributed most to the knowledge
of the economy and natural history of the
Infusoria, has particularly investigated the
structure and mode of action of their cilia.
The substance of his observations has been
already given.

The ciliary motion has been recently ob-
served in the embryoof Infusoria while enclosed
in the ovum.{t

2. Polypi and Sponges.—a. Fresh-water
polypi. The phenomena in question have not
been discovered in the Hydra, which is the
largest and best known of the Fresh-water
Polypi; but they have been seen and described
by many observers in another sort, viz. that
known by the names of the Polype a panache,
or Plumed Polype of Trembley, the Bell-
flower animal of, Baker, and Plumatella, Cris-
tatella, Alcyonella, &c. of other naturalists.
The Rolypes. of this kind are connected in

ups. on a common stock or stem, (4, a,

291, which represents the animal magnified,)
and, each is furnished with a tube (0, 6’),
into which it can wholly withdraw itself.
From time to time they. advance a little way
out of the tubes and display a double row
of. arms or tentacula (c,) ranged: round the
mouth in the figure of a horse-shoe. When
the arms. are spread out in this manner, cur-
rents appear in the surrounding water, which
are ae evident by the motion of any small
pacheies that may.accidentally or intentionally

suspended. in it. The currents pass along
the tentacula, the water being drawn towards

* Abhandlun
Thierchen, 1778.

+ See Miller, Infus. p. 87.

¢ Traité sur le venin de la Vipére, etc, 1781,
tom. i. p. 87. ;

‘§ Sur les Rotiféres, Ann. du Musée d’Hist.
Nat. 1812, tom. xix. et 1813, tom. xx.
ool Salzburg. Med. Chir. Zeitung, 1818, iv. p.

ueber -die Saamen -und Infusions

§| Ueber die Zauberkraft der Infusorien, Nov.
Act. Acad. Czs. Leop. tom. x. p. 127.

_ ** Hist. Nat. de l’Alcyonella Fluviatile, etc.
Mém, de la Soc, d’Hist. Nat. tom. iv. and Chimie
Organique, 1833.

‘ a Abhandl, d. Akad. der Wiss. zu Berlin fiir

tt Wagner, Isis, 1832, p. 383. =,

609

aN my :
Wi ZA.
Uo
\

|
\\
7

them from every side, and the main stream at _
last issues from the midst of them, appearing
as if it came out of the mouth, from which,
however, it really is not derived. The arms
are fringed on their two borders with a mul-
titude of-cilia, (see A, a single arm mag-
nified,) set close together, which vibrate in
regular succession, their motion appearing
like progressive undulations along the ten-
tacula. When. one of the arms is cut off, it
affects the water in the same way as when con-
nected with the animal, its cilia impelling the
fluid in a current, or carrying the separated
arm through it, according as it is fixed or free.
As to the use of these motions, it may be
stated that they serve undoubtedly for renew-
ing the water in respiration, and probably also
to convey food to the animal. Steinbuch,
however, remarked that the currents were most
lively in pure water, and that the extraneous
matters which they conveyed seemed rather to
incommode the animal, which endeavoured
to avoid them ; and from this he inferred that
the currents served chiefly if not solely for
respiration.
embley* and Baker+ observed the currents
produced by this polype, but both erroneously
conceived them to be caused by agitation of
the tentacula. Roesel{ correctly remarked
that, during the production of the currents, the
tentacula were motionless, but not perceiving
the cilia, nor being aware that the arms when
detached still produced motion in the water,
he supposed that the currents were occasioned
by a stream issuing from the mouth. At
length Steinbuch§ discovered that separated
tentacula retained the power of impelling the
water; he distinguished the cilia and their
motion as the cause of the impulsion, and

* Mém. pour servir a l’Hist. d’un genre de
Polype d’eau douce, 1744, p. 212.

+t Of Microscopes, ii. p. 309.

¢ Insecten Belustigungen, tom. iii. 1755, p.

§ Analecten neuer Beobachtungen und Unter-
suchungen fiir die Naturkunde, 1802, p. &9.

610

more correctly described the course of the cur-
rents: the foregoing description is in a great
measure taken from his memoir, Since then
several others* have made similar observations,
among whom we may mention Raspail as
more particularly deserving of notice, though
he here, as in other cases, denies the existence
of cilia.

b. Marine Polypi—The polypi of marine
Zoophytes, on which observations relating to
the present subject have been made, may for
our purpose be conveniently arranged under
three principal forms. ;

The first form of polype (fig. 292) is found
in Flustre and cellular
polypi generally; it ex-
ists also in some spe-
cies which have been
classed among the Ser-
tularie, and probably

revails very extensively
in different tribes of
Zoophytes. The body
(a, 6, c), which is gene-
rally contained in a cell,
is bent on itself, some-
what like the letter Y or
V; the one branch (a)
being the mouth and
throat, the other (6) the
rectum opening by an
anus, and the middle
part (c),which is of a dark
and often of a brown co-
lour, being the stomach probably with some
accessory organ. The mouth is surrounded
with a variable number of long straight ten-
tacula or arms, fringed on both of their lateral
margins with cilia. When the arms are ex-
anded, the cilia are thrown into rapid motion,
which has the appearance of undulations pro-
ceeding along the fringes, upwards on one side
of the arm or from its root to the point, and
downwards on the other. While the cilia are
thus moved, they produce currents in the water,
as described in the Fresh-water Polype, and
here also the currents in all probability serve
for respiration and the prehension of food,
Besides these motions in the water in the
neighbourhood of the tentacula, a revolving
motion of particles is observed within the
body: small particles of extraneous matter
which enter the throat are moved round
within it; and the contents of the stomach
and rectum undergo a very singular revolving
motion round the axis of the cavity. These
internal motions, Dr. Grant conjectured, might
be owing to internal cilia; and I have been
able to satisfy myself of the actual existence
of such internal cilia, by means of a Wollas-
ton’s doublet of one-thirtyfifth of an inch focus ;
they are very evident in the throat; in the
stomach they are most distinct in the part
adjoining the rectum (indicated by d in the

Fig. 292.

Polype of a Flusira
an its cell.

* Vaucher, Bull. de la Soc. Philom. An xii. ;
Raspail, Mém. de la Soc. d’Hist. Nat. de Paris,
ioe 1827; Meyen iiber Polypen, Isis 1828, p.
1225.

CILIA.

figure), and they are clearly to be seen on
the whole internal surface of the rectum (b). _

I have nowhere more clearly seen the above-
mentioned phenomena than in a zoophyte,
whose polype, though differing somewhat from
the first form, may yet be referred to it. This
zoophyte (fig. 293, A, B) has a creeping stem

Fig. 293.

(a, a), which adheres to shells, or twines round
the stems and branches of other zoophytes,
(as b in the figure); the polypes are supported
on soft pliable fleshy stalks (c), which the crea-
ture moves from time to time; their body (d,
and B more magnified) is bell-shaped and
consists of a transparent brownish skin or
envelope containing the mouth and throat (e),
the stomach (g), and rectum (2). The mouth,
or expanded aperture of the animal, is sur-
rounded by a prominent lip or border (j, 2),
to which the arms are attached. Cilia are
distinctly visible on the arms, and within the
mouth and stomach; they are moved very
briskly, and small extraneous particles indi-
cating currents in the water are hurried onwards a
towards the arms, as pointed out by the arrows '
at k,k; many of these particles descend along

the inner side of the arms to their base, as

shown by the dotted arrows 0, 0, e, and thence }
into the cavity of the mouth, from which, after E
being moved about for some time, the greater

number are thrown out. It would seem that N
the particles of food or other solid matter,

|
{
7
'

—_— i

after being conveyed to the inside of the arms,
take then a different course from the stream
of water. The latter passes inwards between
the arms, and issues from the middle of the
irregular circle which they form (as at m,m),
carrying with it such solid matters as are not
arrested on the arms; but the bodies which
enter the mouth are slowly carried along the
inside of the arms (as ato, 0), and in close
contact with them till they reach their base.
The motions of the contents of the stomach
and its cilia appeared as in the Flustra. —
I could perceive none in the rectum. Mr,
Lister has described the same phenomena ina —
zoophyte closely resembling this one in the —
structure of the polypi, but differing in the —
character of the stem.* i

* Phil. Trans. for 1834, p. 385.

CILIA. 6il
In the second form (fig. 294) the stem and
Fig. 294.

* Campanularia.
branches are formed externally of a tough
(generally horny) substance, and within this
of a transparent soft tissue, which is tu-
bular and contains a granular matter. The
polypi resemble hydre; each is lodged in
a horny cell (a, a), from which it partially
protrudes itself; one orifice surrounded with
tentacula serves both for receiving aliment
and discharging feces; this leads to a stomach
(6), which communicates through an opening
(c) at the bottom of the cell with the interior

of the tubular stem and branches, the attached

part or base of the poly being continuous
with the soft internal tube, of which the po-
pe might be regarded as a prolongation.
n this form of polype, which exists in most
true species of Sertularia, Campanularia, and
Plumularia, and in allied genera, the tentacula
or arms are destitute of cilia and incapable
of giving an impulsion to the water. But a
very remarkable motion has been observed by
Cavolini* and Mr. Lister¢ in the granular
matter contained in the stem and branches.
Although this motion has not been traced to
the agency of cilia, yet as it is connected with
our subject, I shall briefly notice it here.
When the stem and branches of the above-
named zoophytes are examined with a high
magnifying power, a current of granular par-
ticles is seen running along the axis of the
tube. The current, which is compared to the
running of sand in a sand-glass, after con-
tinuing one or two minutes in the same direc-
tion, changes and sets in the opposite one,
in which it continues about as long, and again
resumes the first, thus alternately flowing
along the stem to the extremities of the
branches, and back again. The change of
direction is sometimes immediate, but at other
times the particles are quiet for a while, or exhibit
a confused whirling motion for a few seconds
before the change takes place. Mr. Lister has
discovered that the currents extend into the
stomachs of the polypi, in which and in the

* Memorie per servire alla storia de’ Polypi
Marini, p. 121 and 197; p. 56 and 91 of the Ger-
man Translation.

+ Phil. trans. 1834, p. 369.

mouth a remarkable agitation of particles is
perceptible. When these particles are allowed
to- escape from a cut branch, they exhibit,
according to Mr. Lister, something very like
spontaneous motion. The immediate cause of

ese currents is not apparent ; it seems not to
be muscular contraction of the tube; perhaps,
like the agitation within the stomach, they
may be owing to internal cilia. As to their
use Mr. Lister supposes the circulating matter
“to be a great agent in absorption, and to
perform a prominent part in the obscure pro-
cesses of growth; and its flow into the stomach
of the polypi seems to indicate that in this
very simple family (the Sertularie) it acts also
as a solvent of the food.”—-Page 77. Perhaps
the polypi of the Pennatula and Virgularia
should be referred to this head. In these
Dr. Grant* discovered a constant vibratory
motion within the mouth, apparently pro-
duced by cilia placed round the entrance of
that passage, and he saw minute particles oc-
casionally propelled from the mouth. Their
tentacula, as in the zoophytes last referred to,
did not excite currents.

The third form of polype is found in
Tubularia. Fig. 295 represents a magnified
view of a common species,
the Tubularia indivisa. There
is a transparent horny tube
(a, a), containing a soft mat-
ter, which at the extremity of
the tube is continuous with
the stomach (6) and the mouth
(c). There are two rows of
tentacula or arms, one (d)
immediately surrounding the
orifice of the mouth, the
other (e) further back, be-
tween the mouth and stomach.
The arms are destitute of
cilia and excite no movement
in the water; but Mr. Listert
has discovered a remarkable
motion of particles within the
tube, which has some re-
semblance to the circulation
of globules observed in plants
of the genus Chara. These
particles moved in a current
within the tube, the general
course of the stream being

arallel to the slightly spiral
ines of spots on the tube,
and in the directions marked
by the arrows. On the greater
part of the side first viewed
(the one represented) it set as from the poly-
pus; but on the other side the flow was to-
wards the polypus, each current thus occupy-
ing half the circumference. The tube had a
granulated appearance between the lines of
spots, and beneath this the particles ran. Their
course was even and uniform without any
starting or dancing motion, such as is observed
in the Sertularia. At the nodous parts of the

Fig. 295.
_~j

Tubularia

indivisa.

* Edin. Phil. Journ.
t Phil. Trans. 1834, p. 366. _

612

tube (mm, n) were slight vortices in the current,
and ato near the end of the tube it came over
from the opposite side. Two currents were
continually going on in the mouth and
the stomach, one always flowing down the
sides in the direction e, e, and the opposite
one in the axis. Neither the cause of these
currents nor their use has been ascertained.

Such are the phenomena of the ciliary and
other apparently allied motions in the Marine
Polypi.

Spallanzani seems to have first noticed
them; he observed the currents produced
by the Flustre, but erroneously attributed
them to the agitation of the arms, the
cilia on which he had not perceived. Dr.
Fleming* described the current along the
tentacula in the Valkeria cuscuta (a genus
which he has separated from the Sertulariz,
among which it was previously included,) and
distinguished the cilia with their undulatory
motion. Dr. Grantt discovered the cilia on
the arms of the Flustre and described their
undulatory motion, to which he ascribed the
motion in the water. He also pointed out the
revolving motion of particles within the mouth,
stomach, and rectum, and conjectured that it
was owing to the action of internal cilia,
which conjecture I have been able to verify.
Dr. Grant also discovered the vibratory and
probably ciliary motion within the mouth of
the polype of the Pennatule. Loefling}
first observed the agitation of granular matter
within the stem and branches of the Sertu-
larie. Cavolini afterwards more correctly de-
scribed this as a current of fluid holding
granules in suspension; running first in one
direction and then in the other. Lastly, Mr.
Lister observed anew these internal currents
of the Sertularie, described them more mi-
nutely, and showed that they extended into
the stomach of the polypes. Mr. Lister has
also described the phenomena in the F lustre
previously observed by Dr. Grant. He dis-
covered the currents within the stem’ of the
Tubularia, which, as far as I know, had not
been previously noticed.

c. Sponges.—In the various species of
sponges, water, the element in which they
live and grow, passes in currents through
pores and canals in their substance, in a con-
tinuous manner, entering at one place and
issuing at another. This phenomenon has not
been directly traced to the agency of cilia; it
comes nevertheless to be considered here, as
such an agency is highly probable, and at
least the motion of the water is not owing to
any contraction of the canals in which it flows,
but. is obviously caused by some other kind of
impulsion communicated to it by the surface
along which it passes.

Inacommon sponge we see a number of
pretty large orifices on the surface, each opening
on the summit of a conical eminence or pa-
pilla (fig. 296, a). These openings are named

* Mem. of Wern. Soc. fol. p. v. p. 488.

+ On the Structure and Nature of Flustre. Ed.
New Phil. Journal, vol. iii. 1827.

¢ Schwedische Abhandlungen, 1752, p. 121.

CILIA.

by Dr. Grant the “ fecal orifices.” Innume-
rable small pores occupy the rest of the surface,
and give to it its peculiar character. These
pores penetrate to a certain depth, and lead
into canals (6), which, uniting together and
gradually growing larger, terminate in wide
tubes, which open at the fecal orifices. The
pores, excretory canals, and fecal orifices thus
form continuous passages through the sponge.
In the fresh state they are lined throughout with
a smooth gelatinous coating.

When a living sponge is examined atten-
tively in its native element, the water is per-
ceived entering at the pores and issuing from the
fecal orifices, its course being indicated by the
motion of any floating particles that may be
present. The issuing currents are stronger
than the entering, and are rendered con-
spicuous by excrementitious matters or some-
times ova, conveyed out at the fecal orifices.

When sections of the sponge, including a
greater or less extent of the internal canals,
are placed in water, the fluid, according to
Dr. Grant’s observations, is still evidently f
moved along the internal surface of the portions
of canals, although their continuity with
the rest is destroyed. Dr. Grant could not
detect cilia either in these canals or the pores
which lead to them, but he discovered these ;
organs on the ova of the sponge, which there- R
by execute remarkable spontaneous motions, 4
and he is inclined to attribute the currents in the a
adult sponge also to cilia, which he conceives F
may probably exist, though, from their small-
ness, he has not been able to perceive them. At
any rate he has shewn by most satisfactory
observations, that the current cannot be ascribed
to contractions in the canal, for in none of his
numerous experiments instituted for the pur-
pose, could he discover any sign of irritability,
at least any sign of contraction of the tissue
of the sponge on the application of stimuli.

Naturalists even of the earliest times, whose
attention was directed to the phenomena exhi- —
bited by the living sponge, have remarked that
water entered and passed out from its porous —
substance, but the true course of the fluid
seems to have been unknown, it having been
erroneously supposed to enter and issue by
same orifices. Dr. Grant,* to whose labo
we owe most of the correct information
tained respecting the structure and functions ©
the sponge, demonstrated that the current 1
continuous, and flows always in one directio
as above described, and proved that the

as a

* Edin. Phil. Journal, vols. xiii, xiv. KE
New Phil. Journal, vols. i. and ii. :

Ps

CILIA.

of the water was not produced by contraction
and dilatation of the tissue of the sponge,
which he showed to be destitute of irritability.
Dutrochet had made observations on the same
subject, which were published subsequently*
to those of Dr. Grant, and not anteriorly as he
supposes; he perceived the constant direction
of the current, and ascribed the phenomenon to
endosmosis and exosmosis.

3. Ciliary motion of the ova of Polypi and
Sponges.—The ova or gemmules of several of
these zoophytes execute independent move-
ments, rea produce currents in the surrounding
water. This singular fact was, it appears,
first noticed by Mr. Ellis in 1755,¢ in ex-
amining a species of Sertularia, the Campanu-
laria dichotoma ; but he described the ova or
embryos which he had seen in motion, as
young polypi, already somewhat advanced in
their formation. Cavyolini,{ in 1784 and 1785,
observed the same phenomenon in the ova of
the Gorgonia and Madrepore, and investigated
it more fully. He saw the egg-shaped gem-
mules or ova, on quitting the parent, rise to
the surface, and swim with their large end for-
wards, in a horizontal direction, till they fixed
themselves on some spot where they were deve-
loped. Dr. Grant,§ in 1825, discovered
similar motions in the ova of the sponge, and
detected the moving cilia. The cilia covered
the whole surface of the ovum, except the pos-
terior tapering extremity, and in its motions
the large end of the ovum was always directed
forwards. When an ovum fixed itself, its cilia
still continued to play, by which a current
along its surface was kept up for some time.
Dr. Grant also investigated the movements of
the ova of the Campanularia, previously seen
by Ellis, and of the Plumularia falcata. The
ova of both these zoophytes are contained
within transparent capsules, two or more being
in each capsule, surrounded by a clear fluid.
Dr. Grant distinctly perceived cilia vibrating
on the surface of the ova, and causing, while
within the capsule, an eddying motion of the
surrounding fluid, but propelling the. ova
through the water when extracted from their
capsule, as in the sponge. The ciliary.motion
has also been found in the ova of fresh-water
polypi, having been discovered by Meyen|] in
those of the Alcyonella stagnorum, which is
probably the same with, or at least nearly
allied to the Bell-flower Polype.

By means of the remarkable provision here de-
scribed, the ova of these fixed zoophytes are dis-
seminated, and conveyed to situations suitable
to become the abode of the future individuals.
The same provision undoubtedly serves also to
move the water along their surface for the pur-
pose of respiration. It exists, as will be after-

* L’agent immediat du mouvement vital devoilé,
ee p- 179, and Annales des Sciences Naturelles,
8, tom. xv. p. 205.

+ Hist. Nat. des Corallines, p. 116.
$¢ Memorie per servire alla storia de’ Polypi
Marini, Nap. 1785, p- 8, p. 48 of German trans-
lation.
Edin, New Phil. Journal, vol. i.
Isis, 1828, p. 1225, sqq.

4

. 150.-
{sis, 1830, p. 186.

613

wards shown, in the ova of many other ani-
mals.

4, Acalephe.—Many species of Meduse are
furnished with cilia, or at least with moving
organs bearing a close resemblance to the cilia
of other animals, though in the Meduse they
present several peculiarities. The cilia. are
found in all the Medusz belonging to the order
Ciliograda of Blainville, or Ctenophora of
Eschscholz, of which the genus Beroe is a
good example. Eschscholz* describes them as
small pectinated. or comb-like organs, ranged
in longitudinal rows or stripes on the external
surface of the body, with their flat surfaces in
apposition. Each comb-like organ consists of
many small, flattened, pointed filaments, united
together by a common base, the points being
directed towards the posterior extremity of the
body. They are moved like fins, being slowly
raised and suddenly struck. back, by which
means the body is carried through the water.
In the Beroé and others of similar form, the
cilia point towards the closed extremity of the
body, so that the opposite or open end _ is
carried forward. The animal seems to have
the power of moving more or fewer of these
organs as it may incline, by which means other
motions besides direct progression are per-
formed. The. cilia, when. separated .from
the body with a piece of skin, continue to
move briskly for some time. A longitudinal
vessel runs under each row of cilia, com-
municating with the rest of the vascular
system, and containing a fluid, in which yel-
lowish particles are suspended. Eschscholz
regards these vessels as arteries, and considers
the cilia as respiratory as well as locomotive
organs. Dr. Grant, in describing the cilia of
the Beroé pileus,+ represents the parallel fila-
ments of which the comb-like organs consist,
as united together by a membrane as far as
their points, like the rays in the fin of a fish.

Schweigger compares the vessels which run
underneath the rows of cilia, to the canals com-
municating with the tubular feet of the Sea-
urchin and Asterias; and Dr. Grant seems
also inclined to ascribe the motion of the cilia,
whose filaments he conceives to be tubular, to
their being alternately filled and emptied of
fluid derived from the longitudinal vessel, like
the tubular feet of the Echinodermata. This
view of their mode of action, however, is
scarcely reconcilable with the observed phe-
nomena, as will be afterwards shown in con-
sidering the structure of the cilia in general.
Audouin believed that in the Idya, a genus
nearly allied to the Beroe, the fluid of the
longitudinal vessel, which he supposes to be
water, is sent into the cilia; he therefore
regarded them as respiratory organs. If the
vessel under the cilia in this case, as, in the
Beroé, communicate with the rest of the vas-
cular system, and its contained fluid be re-
garded as blood, then the cilia of the Idya,
which, according to Audouin, are permeated
by the fluid, would bear a certain analogy to
the gills of fishes.

* System der Acalephen, p. 3.
+ Zoological Trans. vol. i. p. 9.

614
Cilia a also to exist in other tribes of
Medusz besides the Ciliograda, but they differ

in form and situation from those described,
and have not been investigated with equal
accuracy.

In Rhizostoma there are certain membranous
appendages attached to the arms or tentacula,
and bearing on their free edge a fringe of short
filaments which are constantly in motion, and
continue so for some time after the arm or
portion of membrane supporting them is de-
tached from the body. These filaments are
described and figured by Eysenhardt,* who
regards them as organs of generation ; they are
probably of the nature of cilia. Similar fila-
mentary organs seem also to exist within the
body in some Meduse. (See AcaLepua,

- 48.
‘ 5. Utisecule a paper published on the
present subject in 1830,+ I mentioned that I
had found the ciliary motion in the Actinia or
Sea-anemony, but gave no description of it. I
have since re-examined various species of
Actiniz with this view, and shall now describe
the appearances ; but to make the description
intelligible, it may not be improper to remind
the reader of some points in the anatomy of
these animals which require to be kept in
wiew.

The body of the Actinia, of which fig. 297

Fig. 297.

Actinia.

is a plan, consists entirely of a soft but tough
substance, exceedingly contractile and irritable.
It is usually cylindrical in shape, one end,
(a, a,) named the base or foot, serving to fix
the animal by adhering to rocks or other ob-
jects ; the other extremity is named the disc,
one-half of which is seen at 6, b, the other
half being removed by a section; it is sur-
rounded at its circumference by the arms or
tentacula (c, c,) in concentric rows, and in its
centre is the mouth (d), or opening of the
stomach, which serves both for the entrance of
food and discharge of undigested remains.

* Nova Acta Acad. Czws. Leop. vol. x. p. 404.
t Edin. Med, and Surg. Journal, vol. xxxiv.

* they continued along the arms as far as the

CILIA.

The stomach (e) is plaited longitudinally on
its inside; vertical membranous partitions
(g; 8, g', g’,) pass from its outer surface to the
inside of the parietes of the body, and to the
base, dividing the intermediate space into
humerous compartments or cells, which com-
municate with each other by openings, as at
&, g’, and also open into the tentacula, as at h.
The latter are conical muscular tubes, commu-
nicating at their base with the cells, and open-
ing at their point by a small orifice, surrounded
by a sphincter muscle. The cells seem also
to communicate with the cavity of the stomach,
and, according to Rapp,* they open in some
species by small orifices on the surface of the
body. The cells and tentacula contain sea-
water, with which the animal can distend the
whole body or any particular part of it. The
protrusion of the tentacula, as is well known,
is effected by their distension with water. The
stomach also is often partially everted and pro-
truded from the mouth by an accumulation of
water behind it. It has not, so far as I know,
been clearly shewn by which of the communi-
cating orifices the water enters. Though I
took considerable pains, I have not been able
satisfactorily to ascertain this point; I may
remark, however, that I have repeatedly no-
ticed water entering at the mouth.

The ovaries and oviducts (k, k,) are lodged
in the cells, and are consequently bathed in
water ; of these it is unnecessary here to say
more than that one part of them consists of a
waving membranous fold like a mesentery, at-
tached by one edge to the sides of the cell, and
at its free border supporting the oviduct,
which resembles a white opaque chord, termi-
nating, after numerous serpentine windings, in
the stomach.

In regard to the ciliary motion in the Actiniz,
T am led from my observations to conclude that
it exists to a greater extent in some species than
in others. In all cases I have found it on the sur-
face of the oviducts and their supporting mem--
branes, which is covered with cilia of very minute
size; also on the internal surface of the sto-
mach, which has similar cilia, and there the
currents follow the direction of the folds of the
membrane. Inonesmall but full-grown species
I found currents commencing near the centre
of the disc, and proceeding outwards in a :
radiating manner to its circumference, whence

points. On examining this species, which
was semitransparent, by transmitted light, I
distinctly perceived moving particles in the
water contained within the tentacula and be-
hind the protruded stomach. The motion of
these particles obviously indicated a current in
the water along the surfaces containing it,
which current, like that on the oviducts, it —
may be inferred was produced by cilia, for it
went on while there was no perceptible con-
traction taking place in any part of the ani:
mal. The particles indicating the currer

* Ueber die Polypen und die Actinien. Weimar,
1829, p. 47. oe
+ Some of these particles were no doubt the ova.

CILIA.

within the tentacula, were moved in two diffe-
rent directions, namely, from the base to the
point, and from the point to the base; and
(supposing the arm spread out_horizontally,)
the outward current was along the under part
of the tube, and the returning one along the
upper: (see 4.) I also observed these internal
currents of the tentacula in a young specimen of
Actinia senilis, which seemed to have been very
recently discharged from the parent; in it also
there were radiating currents on the disc, but
they stopped at the base of the tentacula.
Thus the external currents on the disc and ten-
tacula were found in one species, and they
occur on the disc in some other species in the
young state, but their occurrence in this situa-
tion is by no means general in adult Actinie.

The viveisoniens described are in all proba-
bility connected with the processes of nutri-
tion and respiration. They bear a striking
analogy to those I have observed in the Echino-
dermata.

The ova of the Actinis were observed by
Rathke to revolve round their axis, and occa-
sionally to move straightforwards in the
water. He could detect no cilia or other

moving organs.*

6. Siebecdernate:—The animals of this
class in which I have observed the ciliary
motion, are different species of the Sea-star
( Asterias ), and the Sea-urchin ( Echinus ). In
proceeding to describe the phenomena in the
Asterias, I must first take the liberty of ex-
plaining some points in the anatomy of that
animal, referring the reader for other details to
the proper sources, especially the monograph
of Tiedemann.t

A, Asterias viewed from above.

* Dorpater Jahrbiich. fiir Litt. Stat. und Kunst.
Bd. i. Heft. i. p. 84—86, quoted by Purkinje and
Valentin, p. 32. I have since seen the indepen-
dent motion of the ova when extracted from the
animal, It was shown to me by Mr. Graham

B, Cross section of a Ray.

615

On the under surface of the Asterias, (I
speak of the Asterias rubens in particular,
fe. 298, A, B, C, as it is a large species and
common on our shores,) we observe the mouth
in the centre, and the tubular feet (J, fig. B)
projecting in rows along the under part of the
rays. Nearly the whole surface of the animal
is beset with three kinds of eminences. First,
hard calcareous processes, (a, fig. C,) placed
like studs at some distance from each other.
Secondly, claw-like processes (b, 6); these sin-
gular organs are more thickly set ; they consist
of a solid stem of soft substance, bearing at the
extremity a sort of pincers or forceps of hard
calcareous matter, like the claw of a crab.
They resemble analogous organs found on the
Sea-urchin, only that the maxille or pincers in
the latter consist of three pieces; they were
named antenne or feelers by Monro, but Miil-
ler regarded them as parasitical animals. The
third sort of processes (c, c,) are named the
respiratory tubes, and are the most important
in regard to our present subject. They are
short, conical, membranous tubes, communi-
cating at their base with the internal cavity of
the body, and perforated at their point by an
orifice which can be very perfectly closed.
Most of them are placed in groups or patches,
and, corresponding with each group of tubes,
the fibrous membrane forming the wall of the
body presents on its inside a pit or shallow
depression (e), perforated with holes, through
which the tubes communicate with the general
cavity. Like the tentacula of the Actinie,
which they resemble in several other respects,
they can be distended with water and elon-
gated, or emptied, contracted, and shortened.

C, Part of the section at m, fig. A, magnified,

Dalyell, who had long before observed it. The cilia
could be distinctly perceived. .

+ Anatomie der Rohren Holothurie, &c. Land-
shut, 1816,

616

In the inside of the body the membranous
stomach (g) occupies the middle part, and
from it a pair of lobed ceeca (h, h,) (and 4, i, cut
short) pass into each ray. Within the rays also
we find inferiorly the rows of vesicles (k, k)
which form part of the feet (/,/), and the
ovaries. All the rays communicate through
the middle part, and the whole inside is lined
by a transparent membrane (n, n), which,
like a sort of peritoneum, covers the stomach
and ceeca, attaches each of the coeca by a me-
sentery (0, 0) to the roof of the ray, lines the
fibrous parietes of the body, and 1s probably
reflected over the vesicles of the feet and the
ovaries. Each mesentery encloses a space
(0, fig. B) between its sides, which opens into
the general cavity at the root of the ceca. The
lining membrane passes into the perforated
pits (e), by which the tubes (c) communicate
with the cavity, and sends prolongations through
the perforations into the tubes lining them to
their points. The space (s,s, fig. B) lined by
this membrane contains sea-water, which is
genera!ly described.as entering and issuing by
the respiratory tubes.*

I find the. ciliary motion in four situations,
namely, 1. on the external surface; 2. within
the cavity of the body, or in the space (s)
between its parietes and the viscera ; 3. within
the stomach and cceca; 4. within the’ feet.
In all these situations moving cilia are visible
with the microscope on the respective surfaces ;
they are every where comparatively small, in
some parts excessively so. Though I have not
traced them over the entire extent of each sur-
face, I have no doubt they exist at every point
where currents are produced.

1. On the external surface. The ciliary mo-
tion as indicated by the application of pow-
dered charcoal, occurs over nearly its entire
extent, but with different degrees of intensity.
The strongest currents pass along the outer
surface of the tubes from the base to the point,
as at c’; they are also pretty strong on the
claw-like processes ( 6’) and intermediate skin;
on the feet they are evident but less vigorous.

'2. Within the body the currents take place
on the lining membrane and its reflections. A
longitudinal current runs along the roof, and
another along the floor of each ray, forwards
or towards its point: (see the arrows in fig. A.
These advancing currents are-confined to the
median line and its immediate vicinity; two
retiring currents (7, r,) run backwards (one on
each side) at the place where the sides join the
floor of the ray. Two longitudinal currents also
exist on each of the cceca, an advancing one
(h') on the inferior surface, and a retiring one
superiorly (h, h, fig. A) in the space (0, fig. B)
inclosed within the mesentery, w’ ich, as already
mentioned, opens into the general cavity. The
longitudinal currents, except those within the
mesentery, are, -if for the sake. ofexplanation

* Without denying this mode of entrance, 1
may yet mention, that though I have often seen
the animal slowly distending itself with water, and
again partially emptying itself, 1 could never per-
ceive the fluid entering or issuing at the orifices
described.

CILIA.

(see the arrows in fig. B;) on the vesicles of the
feet the course of these cross currents is ° ied
by the curved surfaces, As the lining membr ne
of the cavity extends into the respiratory tubes,
so currents exist within these likewise, as at ¢.
fig.C. This is proved by injecting turbid
fluid into the ray, when particles are seen
moving within the tubes; and if a few of the
tubes with a portion of the skin be cut off and
placed under the microscope, the fluid which
will still be retained by some of them may be
seen to be in motion, the floating particles
moving from the base to the point and back —
again, as in the arms of the Actinie. —__

3. The motion is very distinct on the inner
surface of the stomach and cceca; the currents
within the ceca follow the same direction as on
their external surface, that is, an advancing
current runs inferiorly from the root to the
point and a returning one superiorly; and at
the sides currents run upwards, following the
ridges or folds of the internal membrane which
result from the lobulated structure of the
coeca.

4. The ciliary motion exists distinctly within
the feet, though the cilia are very small; these
became visible on viewing the edge of a folded
portion with Wollaston’s doublet of one-thirty-
fifth of an inch focus. she

The currents described, as far as 1 have been
able to perceive, preserve always the same
determinate direction. Even when portions of
the ciliated surface are detached, the motion
on them continues, and its direction is the
same as before their separation.

As to the use of these motions, it is most
probably connected chiefly with respiration;
and if such be the case, it would show that in
this animal a great extent and variety of parts
are concerned in that function. The ciliary
motion on the inner surface of the stomach and |
ceca is probably subservient also to the process
of digestion. It is conteivable that by means
of this provision the dissolved or digested food
might be introduced into the ceca, and spread
over their internal surface, there to be duly
mixed with secreted fluids ‘and subjected to
the process of absorption ; the returning cur-
rent serving to bring back the residue, or to
convey secreted fluids into the stomach. Or,
considered as subservient to respiration, the cili- __
ary motion, in diffusing the digested food over
the internal surface of the coeca, may at the —
same time expose it to the respiratory influence
of the water on their outside. 3

These phenomena in the Asterias seem not to
have been previously noticed. Tiedemann,* it
is true, had observed an eddying motion of the
water in the vicinity of the respiratory tube
while the animal was~ slowly -distendin;
emptying itself, but he conceived it to
nothing more than ‘the commotion necessari
produced by the passage of the water throug
the tubes. There can be little doubt that

ite
* f

* Anat, der Réhren Holothurie, ete. p- 40. re

eae) eee Ue ee ae eo

A

CILIA. . 617

phenomenon he saw was caused by the ciliary
motion on the external surface, though he was
not aware of this.

Having entered into these details respecting
the Asterias, I may describe more briefty the
phenomena in the Sea-urchin, the more so as
my opportunities of observing this animal have
been less frequent.

The species submitted to examination was
the common large Sea-urchin of our shores,
Echinus esculentus, described by Monro.*
Its body consists of a globular shell, containing
the viscera. The mouth is placed underneath,
the anus opposite on the upper surface. The
tubular feet are disposed in vertical rows from
the mouth to the anus, the intermediate part of
the shell being covered with moveable spines,
and the singular claw-like organs referred to in
describing the Asterias. As in the Asterias,
there are membranous respiratory tubes, but
they are comparatively few in number, forming
ten small bunches or groups, which are placed on
the under surface not far from the mouth, and
open internally in ten small perforated pits, like
those of the Asterias; they are supposed by
Tiedemann and others to be the channels by
which the sea-water gets into the interior of the
body, and fills the space between the inside of
the shell and the contained viscera. The ali-
mentary canal, commencing at the mouth, rises
through the curious dental apparatus named
Aristotle’s lantern, turns in a waving manner
twice round the inside of the shell, and termi-
nates above at the anus; it is supported by a
mesentery derived from a membrane which lines
the cavity of the shell, and which is reflected
over its contents like a peritoneum. Inside the
shell we also find the ovaries and the rows of
feet. The internal parts of the latter, instead of
being round vesicles as in the Asterias, are broad
laminz enclosing vessels, canals or branched
Cavities, which canals, like the vesicles of the
Asterias, communicate on the one hand with
the tubes of the feet, and on the other with a
common vessel which runs along the middle of
each double row of lamine. The vessels or

aces within the lamine are much branched ;

form a plexus surrounded by a principal
vessel at the border.

I have found the ciliary motion over nearly
the whole surface of the cavity of the body and
the contained parts, which surface, as mentioned
already, is covered by a lining membrane or
peritoneum. Two longitudinal currents run on
the intestine in the same direction, viz. one
along the line of attachment of the mesentery,
the other at the opposite part of the tube. On
the remaining circumference of the intestine
the impulsion is directed obliquely towards the
nearest longitudinal current. In regard to the
lamine of the feet, a current runs down the
middle of each of the double rows, following

course of the longitudinal vessel there
Situated, the direction being from the anus to-
wards the mouth. Lateral currents pass over
the surface of the lamin from their external

* Anatomy of Fishes, &c.
t Accurately described by Monro, 1. c.
VOL. I.

to their internal border, where they join the
middle current; they follow the irregular eleva-
tions on the surface of the lamin occasioned
by the canals or vessels in the latter; hence,
when charcoal powder is applied, the particles
follow winding paths in crossing from one edge
of the lamine to the other, and they are fre-
quently caught in a hollow between two cur-
rents, and whirled about for some time be‘ore
they resume their way. Currents were visible
also on the reflections of the lining membranes
which cover and pass between different parts of
the lantern, and at the internal openings of the
respiratory tubes. The cilia on the parts de-
scribed are excessively small, but distinctly per-
ceptible. The ciliary motion was not detected
on the external surface of the body nor within
the alimentary canal; but in regard to these
parts the observations could scarcely be consi-
dered as conclusive; nor could I determine whe-
ther, as in the Asterias, the phenomenon occurs
within the feet or within the spaces or vessels
of their membranous lamine, though from an
observation of Carus, who states that he saw
globules circulating within these lamin, its
existence in that situation is not improbable.*

This provision in the Echinus is probably, as
in the analogous cases already described, chiefly
subservient to respiration. Tiedemann, who
ascribed a respiratory office to the water within
the animal, expresses himself at a loss to con-
ceive by what mechanism it can be made to
enter and issue from a cavity with unyielding
sides incapable of being expanded and con-
tracted by muscular action ; perhaps the provi-
sion here described may be adequate for this
purpose. Since the above observations were
made, a fact has been mentioned by Ehrenberg,+
from which it appears that the ciliary motion
exists on the external surface of the Echinus on
the spines. The species observed by him was
the Echinus sexatilis. The observations of Carus
and Ehrenberg here referred to comprehend
the only facts hitherto published on the ciliary
motions of the Echinus which have come
under my notice.

7. Annelida.—In proceeding to describe the
ciliary motion in animals of this class, in
several of which it occurs, it seems advisable
to begin with the Aphrodita, as the phenomena
in this animal present a remarkable analogy
with those we have been considering in the
Echinodermata.

A great part of the body of the Aphrodita
aculeata, or Sea-mouse, (of which fig. 299, A,
represents a cross section,) is occupied by the
abdominal cavity, (a,a,a.) Along the superior
wall of this cavity a row of cells (6) is placed
on each side, which below open into the abdo-
men, but above, or exteriorly, project on the
dorsal surface as oblong transverse eminences.
Each alternate cell on the back bears a broad |
membranous scale (c,c), and each of the in-
termediate ones a small indented process. On
the back a covering of felt-like substance (d )
is stretched from side to side like a roof over

* Analecten zur Natur-wissenschaft, etc. Dres-

den, 1829, p. 152.
+ Miiller’s Archiy. Band 1, p. a
Ss

.

618

oy) rrr tt ce ——
Gr - sx

A. Cross section of the Aphrodita aculeata.

B. Alimentary canal and ceca, seen from above.

_ the cells and scales, inclosing them in a space
(e) to which the water has free access. Re-
turning to the abdomen, we find the nearly
straight alimentary canal, its anterior third
(f; fig. B) forming the stomach, the remaining
part or intestine (g, fig. A and B) being fur-
nished on each side with a number of long
ceca (h), whose branched extremities (i, 7)
are in part lodged in the before-mentioned
cells. The abdomen is lined with a de-
licate peritoneal membrane, which also lines
the cells, and is reflected over the viscera.

In the living Aphrodita the water freely
enters and issues from the space (e) beneath
the felty membrane, passing over the external
surface of the cells and their appendages. The
flow of the water in this passage is produced,
as I have repeatedly observed, by the elevation
and depression of the scales, and on no part
of the surface over which the fluid passes is
the ciliary motion to be observed. But the
water also enters the cavity of the abdomen,
though it is doubtful by what orifices this takes
place, for my endeavours to find those de-

CILIA.

scribed by Treviranus* in the alternate in-
tervals of the feet have never been successful. ’
In whatever way it may happen, however,
there can be no doubt of the fact that the :
water enters the abdomen, and consequently
fills the dorsal cells and surrounds the intestine
and its coeca, which last organs, according to
Sir Everard Home and Treviranus, exercise a
ry ened function, an opinion which derives
additional probability in considering the phe- :
nomena of the ciliary motion to be here de-
scribed. The ciliary motion exists in two ;
Situations, 1st, on the external surface of the
intestine and ceca and the internal surface of
the cells, which surfaces are in contact with
the contained water; 2dly, within the intes-
tine and ceca, or on their internal surface. The
motion as usual persists for some time in de-
tached parts, and the direction of the currents
is constant. On the intestine the currents pass
from the inferior surface round the sides to the
upper part (as marked by the arrows). On
the coeca the direction is outwards or towards
the cells, and the motion is very distinct at
their extremities. The direction on the inner
surface of the cells was not completely made
out, but it seemed to be chiefly downwards.
Nor was the direction of the impulsion satis-
factorily ascertained on the internal surface
of the intestine and ceca, though of the ex-
istence of the phenomenon in that situation
there could be no doubt.
From what has been stated, it appears then,
first, that in the Aphrodita the water finds
access to the outside of the cells, over which
it is conveyed by the elevation and depression
of the dorsal scales, and to the inside of the
cells, over which, as well as over the external
surface of the intestine and its ceecal appen-
dages, it is moved by the action of cilia. In
both situations the motion of the fluid is pro- ,
bably subservient to the respiratory function,
and if it really be so, we must reckon the
scales, the cells, the alimentary canal, and its :
appendages, as constituting the respiratory ap-
paratus. Secondly, that the ciliary motion
exists also on the internal surface of the in-
testine and ceeca, where it is likely connected
both with respiration and digestion. In all
this we cannot overlook the analogy which
subsists between the Aphrodita and Asterias.
In both the water is conveyed, though by a
different mechanism, over the external surface
of the body; in both it enters the cavity con-
taining the viscera; in both it is moved along
the parietes of the cavity and surface of the —
viscera in a determinate direction by the —
agency of cilia; and, lastly, in both the ciliary —
motion occurs on the internal surface of ‘the:
digestive organs. | ae
I first observed the ciliary motions in t 1€

‘Aphrodita aculeata in 1830, at the same time

with the late Mr. Cheek, who gave 1 otic
of the fact in the journal of which he we
conductor ;+ but most of the observations ¢

* Zeitschrift fiir Physiologie, Band iii. p. | 5 ’
+ Edin. Jour, of Nat, and Geog, Science, April,
1831, p- 246. . F r :

CILIA.

which the preceding account is founded, were
made more recently. There is no mention of
the existence of the phenomenon in the Aphro-
dita to be found in systematic works on com-
parative anatomy, nor in any of the special
memoirs on that animal which I have had an
opportunity of consulting.

e ciliary motion exists in several other
animals belonging to the class Annelida. It
is remarkably distinct, and easily observed, on
the branchie or gills of the Serpula. These
organs consist of two bunches of pinnated or
_ feather-like processes, which the animal pushes
__ forth from the calcareous tube in which it lives,
and spreads out in a radiating form. The
edges of the branchie, both of the stems and
of the leaflets, are fringed with cilia, which
exhibit their vibrating and undulating motions,
and cause a constant current of water over the
surface of the gills, serving here, no doubt, as
in analogous instances, at least chiefly for
respiration.

n a paper already referred to,* I mentioned
having observed the phenomena in question in
the Amphitrite. The animal meant was a com-
mon marine tubicolar worm (fig. 300), which

Fig. 300.

A. Dorsal surface, natural size.

B. Part before a, b, magnified.

C. A gill magnified.

D. One still more magnified, to show the spiral
ridges and cilia.

a “pgm to be the same with that figured by
Ellis (Corall. plate 36), and described by Cuvier
as the Amphitrite a ruche, with which figure it

s, except that it bears two rows of simple

ents on the back, which, for reasons that
will appear, I was led to regard as gills. But
if these are really gills, the animal must, it
seems, be arranged with the Dorsibranchiata,
probably as a Sabella. The currents in this
worm forwards along the back, be-
tween the rows of gills (as marked in fig. B),
and along the gills themselves (see C), whose
points are directed forwards. The conical fila-
ment of which each gill consists is marked on
one side by ridges (see C, D), crossing it
obliquely like segments of a spiral; and on
these ridges as well as on the point of the gill
the most conspicuous cilia are placed. e
cilia are comparatively large and curved,
their points being turned towards the summit
_ of the gill, which figure they retain when their
motion is stopped. The gills contain large

_ * Edin. Med. and Sur, Jour. vol. xxxiv.

3
;
7 4
a“
>
Ee
:
:
t
|
;
.

619

bloodvessels, which when distended give them
a bright red colour.

The ciliary motion occurs also on what seem
to be the branchiz of another tubicolar worm,
the name of which is unknown to me; the
organs in question are placed at the anterior
extremity of the animal, concealed by a pro-
fusion of long serpentine tentacula.

Lastly, Mr. Cheek* observed the ciliary
motion in the Sandworm (Arenicola piscato-
rum). It was seen on the inner surface of the
internal vesicles, which Sir Everard Home de-
scribes as livers. Nothing similar exists on the
tufts of filaments which form the gills.+

8. Mollusca.— The ciliary motion prevails
very extensively in this division of the animal
kingdom. It seems to exist generally in the
Gasteropodous and Acephalous Mbollusca.
There is some uncertainty as to its existence
in the Cephalopoda; I have repeatedly sought
for it in that class, but without success.

It occurs on the surface of the respiratory
organs, and often on other surfaces over which
the water has to pass in the act of respiration.
It also exists within the alimentary canal, at
least this has been ascertained in several spe-
cies of Gasteropoda and Acephala, and may
be presumed of the rest. Moreover, in some
of the Gasteropoda, it is very manifest on the.
horns or feelers, which suggests the possibility
of its aiding in these instances in the exercise
of the sense of touch or smelling. In all
cases the impulsion maintains a determinate
direction, which continues the same in parts
detached from the animal. In salt-water spe-
cies, the action of the cilia and impulsion. of
the fluid, are instantly stopped by putting the
parts into fresh water.

The ciliary motion also occurs in the embryo
of the Mollusca within the egg, which pheno-
menon will be considered in the next section.

A. Gasteropodous Mollusca.—Of this class
the phenomena have been observed by myself
and others in the orders of Nudibranchiata,
Cyclobranchiata, Pectinibranchiata, and the
aquatic Pulmonifera, in one or more species
of each.

a. Nudibranchiata.—In this order, in which
the gills are entirely exposed, the currents can
be very easily observed. .The Doris, a species
of which is represented in the adjoining figure
(301), may serve as an example. The arbo-
rescent gills (a, a) are ranged in a circle round
the anus, and their stems and branches are
covered with cilia. Currents pass over their
surface, the general direction being towards
the points; small portions detached still ex-
cite currents in the same direction, and, if free,
move through the water in the opposite one.
I have examined three species of Doris, and

* Edin. Journ. of Nat. and Geog. Science,
April, 1831, p. 245.

+ The ciliary motion has also been observed in
Planariz, on the surface of the body by Gruit-
huisen, (Salzb. Med. Chir. Zeit. 1818, vol. iv.)
and by Purkinje and Valentin Gruithuisen also
discovered it in the Nais proboscidea, in the pos-
terior part of the intestine, (Nov. Act, Acad. Cas,
Leop. xi. p. 238.) aks

s

620

in one of them, the D. cornuta, the ciliary
motion was very strong on the club-shaped
feelers; perhaps it may be the same in all.
I also examined the Tritonia and Eolis belong-
ing to this order, and found the ciliary motion
in corresponding parts.

b. Cyclobranchiata.—In the Patella or
Limpet (fig. 302, representing the under
surface), the gills form a series of simple

Fig. 302.

Patella.

B. Portion inclosed between the lines ¢ and d,
magnified to show a, a, the branchial la-
mine, and Bb, b, the circular border of the
mantle.

lamine (a, a) attached within the circular
border of the mantle (b, b). The currents pass
inwards from the edge of the mantle to the
gills, then over the surface and along the border
of each branchial lamina, from its outer or
lower to its inner or upper edge, as indicated
in the figure by the arrows. In the Limpet
the ciliary motion is also found on the inner
surface of the alimentary canal.

In the Chiton or Oscabrion (fig. 303), the
only other genus of this order, the gills are
situated as in the Limpet, but are of a more
complex structure. Each consists (at least in
the species examined by me) of a triangular
lamina, with a series of smaller lamine set

CILIA. Ree ,

on each side of it,
diminishing in size.
as they approach its
point. The currents
on each of the gills
are directed towards
its apex, and also
pass between the
secondary lamine
over their surface
and along their

edges: a, a, are the b ™

gills; b one of the

gills magnified,

showing its lamine ; Chiton.

c the same viewed

endwise. The atrows mark the direction of

the currents.
c. Pectinibranchiata— The common Buc-

cinum (fig. 304) may serve as an example of

Fig. 304.

MXN

(RY

——— ea

Buccinum Undatum.

this order. The gills, as accurately described
by Cuvier, are attached to the roof of a bran-
chial cavity or recess formed between the man=
tle (a, a) and upper part of the body (6) in the
last turn of the shell, and opening anteriorly
by a broad slit. At the left end of the slit the —
edge of the mantle is prolonged in the form —
of a groove (c), which prolongation is ts
the syphon, and is lodged in a corresponding
groove of the shell. On detaching the roof
of the branchial cavity at the left side, and
reflecting it (as represented in the figure), we
find attached to it, first, the gills, consistin
of a short double row (d) and a longer sin
row (e) of lamine, the latter being larg
secondly, to the right of the gills, the so-nan
mucous lamine (f,f); thirdly, still more
the right, the rectum (g). i
The water enters “by the syphon, and isst
at the right extremity of the branchial s
The ciliary motion and currents take place
the gills, mucous lamine, and rectum, and

CILIA.

the inner surface of the mantle, where it forms
the roof of the branchial cavity. Their situ-
ation and direction are indicated in the figures
by the arrows. B is an enlarged view of a
few lamine from the larger series, h the at-
tached border, i point, m left, and n right
border. Currents pass between these lamine
along the surface and border of each, as
shewn in B; C is a magnified view of the
lamine of the smaller set, on which the di-

621

rection of the currents is marked; the direc-
tion on other parts will be understood by re-
ferring to figure A.

The ciliary motion is very manifest within
the alimentary canal, in the gullet, stomach,
and intestine; the direction of impulsion is
from the mouth towards the anus.

The ciliary motion has been observed by
myself and others in the Paludina vivipara,
a fresh-water snail belonging to this order,

Fig. 305. A

in which also Purkinje and Valentin state
that they observed it within the alimentary
canal; and Gruithuisen* has described
the phenomenon as seen on the branchiz
of another fresh-water snail, which he
names Valvata branchiata. He saw moving
cilia, which caused an incessant agitation
in the water; but he does not state whether
the motion followed any constant direc-
tion, although we may infer that this was
the case. He rightly attributed to these
motions a respiratory function, but seems
not to have observed that similar pheno-
mena existed in other Mollusca.

d. Pulmonifera. The ciliary motion is
not confined to those Mollusca which
breathe by gills, for it occurs also in the
Lymnea and Planorbis, which, though
they live in water, breathe air by a pul-
monary sac. In these instances the impulsion of the water
takes place on the surface of the tentacula, which is covered
with cilia. If these parts are to be regarded as organs of
sensation alone, the ciliary motion observed upon them,
as well as that which occurs on the tentacula of bran-
chiferous species, must be considered as connected with
the function of sensation; but the tentacula, which in the
Lymnza are broad vascular lamine, might be conceived
also to perform the office of accessory organs of respiration,
in which case the pulmoniferous Mollusca here mentioned
would possess organs both of aerial and aquatic respiration.
In the Lymnea the motion has also been observed by
Purkinje and Valentin within the alimentary canal.

B. Conchiferous Acephela—The motion in question has
been found in several bivalve Mollusca, both of salt and
fresh water, and there can be little doubt that it exists in all.

The common Sea-mussel (fig. 305) will serve as an
example of the class. It will be recollected that the
gills of this animal (fig. A, c, c’, d,) have the form of

* Nova Acta Acad. Cas. Leop. x. p. 437,

ELTA

— >. ee =~

; an ag

| f _F. Portion of a bar of the gill, with
the cilia, highly magnified.

622

leaves, tliere being two on each side inclosed
between the lobes of the mantle (a, a, a’,
a"). Between the gills are interposed what
is called the foot (f) and the prominent part
of the abdomen, which separates the two
of the right side from those of the left.
Each gill or leaf consists of two layers, which
are made up of vessels set very close to one
another (fig. D,) like the teeth of a comb, or
like parallel bars, across the direction of the
gill, and perpendicular to the great vascular
trunks running along its base, with which they
communicate. The two layers composing each
gill are connected together at its edge, and by
a few points of their contiguous surfaces.
the base only one layer is fixed, the other ter-
minating at this part by a thick unattached
border (e, e), under which a probe may. be
passed into the interior space between the two
layers. This is further explained by jig. B,
which represents a section of the two gills of
one side cut parallel to the bars. The layers
(ec, fc,) are united at the edge of the gill (c),
but separated at the base, the one being fixed
at f, the other ending by a free margin, e.
£, 8, is the space between the layers; it com-
municates with the excretory orifice (A, fig. A).
Fig. C shews the upper part of the gill,
(c, A, fig. B,) viewed similarly, but magnified
eighteen diameters. Two bars, (ec, f c,) be-
longing to opposite layers, are seen; they are
shaped somewhat like the blade of a knife,
with a thick round external border (e), and a
thin internal edge (h) opposed to the corres-
ponding one of the other layer, with which it
is connected at a few places by cross slips,
i, t, fig. C, and k, k, fig. B, where they are
longer, the space at this part being wider.
. Fig. D is a small portion of one of the layers,
(t, t, fig. A,) magnified eighteen diameters.
The bars are connected laterally with the adja-
cent ones of the same layer at short intervals,
by round projections on their sides, (a, a, a, a,
in figs. D, C, and E,) in which last they are
still more magnified. Each of these projec-
tions adheres but slightly to the corresponding
one of the collateral bar, and its surface is
covered with small filaments resembling the
cilia in the other parts, only their motion is very
slow. Besides the gills, the mussel has four
triangular lamine (m, m, n, fig. A,) placed
round the mouth, which probably serve for
respiration ; they have been named labial ap-
pendages, tentacula, or accessory gills.

When a live mussel is placed in a vessel of
salt water, it is soon observed to open slightly
the two valves of its shell, and at the same
time a commotion is evident in the water in its
vicinity. This is occasioned by the water en-
tering at the posterior or large end of the
animal into the space between the lobes of the
mantle in which the gills are lodged, and issuing
near the same place by a separate orifice in a
continued stream, as represented by the arrows,
(g and A, fig. A), g being the entering and h
the issuing stream. The existence of this con-
tinuous current is well known, but the agency
by which the water is set in motion appears not
to have been, at least generally, understood. It

At -

CILIA.

can readily be shewn that here, as in the in- —
stances already described, the water receives its
20 Wee from the ciliated surface of the gills
and other parts over which it passes, and that
it is carried along these surfaces in a determi-
nate direction. The whole surface of the gills
and labial appendages or accessory gills, the —
inner surface of the cloak, and the surface of
some other roduce this effect, and the
combined action of the cilia over this extensive
surface gives rise to the main current which
enters and issues from the animal.

On removing one of the valves, turning down
the cloak, as represented at 0, and putting
moistened charcoal powder on the surface of
the gills, the finer part of the powder soon dis-
appears, having penetrated through the inter-
stices of the bars or vessels into the space
between the two layers of the gill. On arriving
there a part is often forced out again from
under the border of the unattached layer at the
base of the gill, but most of it is conveyed —
rapidly backwards between the two layers, and
is carried out at the excretory orifice with the
general current, its course being indicated by
the dotted arrows in the figure. The coarser
particles remain outside the gill, and are slowly
carried to its edge, following the direction of
the bars ; they then advance along the edge of
the gill towards the forepart of the animal, as
shewn by the entire arrows. It thus appears
that the water first passes in between the
lobes of the mantle to the external surface o.
the gills; it is then foreed into the space
inclosed between their layers, from whence it
is driven out at the excretory orifice, to which
the inclosed spaces of all the gills lead. As
this process continues to go on after the shell
and lobe of the mantle of one side are removed, __
it is evident that the motion of the water must |
be mainly produced by the cilia of the gills, to
be immediately described. By their agency
the fluid is forced into the space within the
gills, and this operation taking place over
the whole extent of the gills, must, by its
concentrated effect, give rise to a powerful
issuing stream at the excretory orifice, of which
the entering stream seems to be a necessary
result.

The cilia are found on the gills, the acces-
sory gills, the inside of the mantle, and the ~
foot. Only those on the gills require particular —
notice. Most of them are arranged along the ~
sides of the vessels or bars (a, a, fig. F), com-—
posing the gills, in two sets, one nearer the
surface consisting of longer and more opeaaa
cilia, (6, 6,) the other close to the first, but a
little deeper, and consisting of somewhat shorter
and nearly transparent cilia, (c, c.) Both
are in constant motion, but of this it is dif
to convey a correct idea by description. T
more opaque cilia, or those of the exter
range, appear and disappear by turns, as if t

were continually changing from a horizontal
a vertical* direction and back again.

* By vertical is here meant a direction perpe
cular to the plane of the gills, which directio:
vertical when the gills are spread out und
microscope. ; bee

motion of the other set consists in a succession
of undulations, which proceed in a uniform
manner along the sides of the bar from one
end to the other. It might be very easily
mistaken for the circulation of globules of a
fluid within a canal, more especially as the
course of the undulations is different on the
two sides of the bar, being directed on one
side towards the edge of the gill, and on the
other towards the base.- But besides that the
undulations continue for some time in small
pieces cut off from the gill, which is incon-
sistent with the progression of fluid in a canal,
the cilia are easily distinguished when the un-
dulatory motion becomes languid. When it
has entirely ceased, they remain in contact with
each other, so as to present the appearance of
a membrane, (d,d, fig. F.) Besides the two
rows of cilia just described on each side of the
bars, others are placed in a less regular manner
on their external and internal borders. The in-
ternal (h, fig. C) are exceedingly small ; they
extend upon the cross slips, (i, fig-C). Those
on the external borders are very numerous and
thick-set, and of considerable size, especially
on the extremity of the bar at the edge of the
gill (c, fig. C); their points are directed to-
wards the edge of the gill. It is probably by
the agency of these last-mentioned cilia that
the particles of food or other foreign matter
are conveyed along the surface of the gill to
its edge, and then onwards to the mouth,
while the others may serve principally to force
the water through the interstices of the bars
into the space inclosed between the layers,
and from thence out at the excretory orifice.

As in other instances, detached portions of
the ciliated parts excite currents in the same
direction as before their separation, or swim
through the water in the opposite direction.
It is very remarkable that when the parts are
immersed in fresh water, the currents and mo-
tion of the cilia are almost instantaneously
sto :

e ciliary motion is equally apparent on
the respiratory organs of the Oyster, River-mus-
sel, and other bivalve Mollusca which have
been submitted to examination. Purkinje and
Valentin pointed out its existence also in the
alimentary canal of the River-mussel, which
observation I have confirmed, and I have found
the same to be true of the Sea-mussel. The
impulsion apenas to me in both instances to
be chiefly directed onwards, that is, towards
the anus.

c. Tunicata ( Ascidie).—In the paper pre-
viously referred to, I stated that I had not.been
able to perceive the ciliary motion in the Ascidia,
but added that the observation seemed inconclu-
sive, as the specimens examined had been some
time out of the water. Since then I have seen
the phenomena as distinctly in the Ascidiz as
in other Mollusca. The observations were made
on a common species found adhering to rocks
in the Frith of Forth at low water-mark, and
as far as they go they agree with those lately
made by Mr. Lister,* on a small aggregated

* Phil. Trans. 1834, p. 378.

CILIA. 623

species, the substance of which being nearly
transparent enabled him to trace the currents
more completely. For this reason it seems
preferable to borrow his description.

The annexed figures (A and B) represent

Fig. 306.

one of these Ascidie on
its peduncle, with the
opening of the mouth (g)
and the funnel (f’) in
front. The outer covering
is a tough coat («), lined
internally with a soft sub-
stance or mantle (b). A
great part of the interior
is occupied with the
branchial sac (c), whose
cavity terminates upwards
at the oral opening, and
is closed at the ‘bottom.
It is united to the enve-
lope or to the mantle
above and behind; the
juncture (e, e,) beginning
in front of the oral open-
ing, extends backwards
on each side of it, and then downwards along
the middle of the back (a’, fig. A.) A vacant
space (f, f,) is left between the sac and mantle
at the sides and front, which ends in the
opening of the funnel. The sac opens infe-
riorly into the esophagus (h), which leads to
the stomach (7), the intestine passing forwards
and opening by the vent (k) into the funnel.
On its sides and front the branchial sac is per-
forated by four rows of narrow vertical slits or
spiracles (m, m), and through these the water,
which flows constantly in at the mouth when
its orifice is open, appears to be conveyed to
the vacant space (f) between the sac and
mantle, and it then escapes at the funnel.
The sac seems extremely thin between the
spiracles, but their edges are thickened, and
they are lined with closely set cilia, which, by
their motion, cause the current of water. When
they are in full activity, the effect upon the eye
is that of delicately toothed oval wheels, re-
volving continually in a direction ascending on

624

the right and descending on the left of each oval,

as viewed from without; but the cilia them-

selves are very much closer than the apparent

teeth, and the illusion seems to be caused by a

fanning motion given to them in regular and

quick succession, which will produce the ap-
earance of waves, and each wave answers
ere to a tooth.

Whatever little substances alive or inanimate
the current of water brings, if not ejected as
unsuitable, lodge somewhere on the surface of
the branchial sac, along which each particle
travels horizontally with a steady slow course
to the front of the cavity, where it reaches a
downward stream of similar materials (h') ;
and they proceed together, receiving accessions
from both sides, and enter at last, at the
bottom, the w@sophagus (h); this is a small
flattened tube which carries them, without any
effort of swallowing, towards the stomach.

Mr. Lister observed similar phenomena in a
species of Polyclinum, another form of com-
pound Ascidia, in which an excretory funnel is
common to several individuals. Mr. Lister,
p- 385, has adverted to the resemblance be-
tween the Ascidiz and a zoophyte of a similar
form to that here described at page 610. I may
here point out an analogy on the other side, no
less striking, between the Ascidiz and bivalve
Mollusca, in regard to the phenomena now
under consideration. In both cases the water
enters at one opening, and meeting with the
surface of the membranous gills, passes through
slits or interstices between their vessels into a
space on the other side of the gill, which space
terminates at another external opening, by which
the water issues. In both cases also the mar-
gins of the slits in the gills are fringed with
cilia which exhibit a waving motion, the waves
proceeding in opposite directions on the two
borders of the slit. Lastly, in both cases,
while the water and finer particles of matter
floating in it pass through the slits, the coarser
matters are conveyed along the first surface of
the gills towards the mouth. The difference
lies chiefly in the nature and form of the ex-
ternal covering and the form of the gills in
each; the membranous gills in the mussel
being folded into double leaves on each side,
and in the Ascidia being formed into a tubular
sac; the space between the lamine of each
leaf in the mussel corresponding with the
space (f) enclosed between the branchial sac
and mantle in the Ascidia, both these spaces
leading to the excretory orifice.

The remarkable appearances in the Mollusca
described above could not wholly escape the
notice of naturalists and microscopic observers.
Thus we find Ant.de Heide,* a Dutch physician
of the end of the seventeenth century, observing
the appearance produced by the ciliary motion
in the Sea-mussel; he names it “‘ motus radio-
sus,” or “ tremulus.” He found it m most parts
of the animal, but in none more evident than the
gills (cirri pectinati), in which it is most easily
examined. “I call the motion radiant,” says
he, “ because it proceeds from the whole sur-

* Anat. Mytuli, &c. 12mo. Amst, 1684,

CILIA.

face of the cirrus (gill) almost in the same way
as ait-bubbles issue from crabstones or metals
while undergoing solution ; it may be called
tremulous, because the parts affected by it
vibrate. is motion goes on not only in
the entire gill connected with the rest of the
mussel, but even in the smallest pieces cut off _
from it, which by their radiant motion swim
briskly through the sea-water.” wae

Leeuwenhoek likewise appears, from various
passages in his writings,* to have perceived the
moving cilia in the Oyster and Mussel; he
noticed also the existence of the motion in
detached portions. His observations, so far as
they go, are correct; but he takes no notice of
the currents in the water; nor does he seem to
have perceived the relation of the phenomenon
to the respiratory or other functions, or indeed
to have formed any opinion regarding its phy-
siological use.

Baker alludes to Leeuwenhoek’s discoveries,
and relates an appearance observed by himself
in the Fresh-water Mussel, which must have
been caused by the ciliary motion.+ He states
that “ on snipping off a piece of the transpa-
rent membrane (gill), and viewing it with the
microscope, the blood will be-seen passing
through numbers of veins and arteries, and if
the extremity of the membrane be viewed, the |
true circulation or the return of the blood from
the arteries through the veins will be shewn.”

Dr. Hales, in his Statical Essays, (vol. ii.

p- 93,) plainly alludes to the same phenomena.

Among more recent writers, Professor Ehrman

of Berlin, in a memoir on the blood of the

Mollusca, published in the Transactions of the

Royal Academy of Sciences of Berlin for

1816-17,{ has described an appearance no-
ticed by him in Mya, Anodonta, the Oyster,
and other Bivalves, which seems evidently to
have been produced by the ciliary motion. He
states that on viewing the inner side of the
labial appendages, accessory gills, or tentacula ;
of these Mollusca, while it was illuminated bya
strong light falling in a particular direction, he "
perceived a very rapid: and incessant motion d
along the transverse stripes or furrows obser-
vable on the surface of the part. The motion
proceeded along each stripe like a series of
oscillations. It continued for some time in
portions cut off from the organ. He next ob-
served that a number of round vesicular bodies
escaped from the furrows or rt at the bre
where they were cut, which bodies moved to
and fro and as it were spontaneously in the
water; and it seemed to him that in proportion
as these bodies escaped, the oscillatory motion
relaxed in intensity. From these facts he con= —
cluded that the motion appareut on the surface
of the part was produced by the agitation of —
these vesicles or animated molecules within |
the furrows ; that is, he supposed the furrows
to be covered by a membrane to which an

—=— = ee ae

* Epist. 83, in Opp. i. p. 463, 482. Anat. et
Contemp. p. 52 in Opp. ii. Ibid. p. 27. Contin.
Arcan. p. 17 in Opp. li. }

+ Of Microscopes, &c, vol.i p. 128.

¢ P. 214, seq.

CILIA.

oscillatory motion was communicated by the
agitation of the globules underneath it. He
ived the motion in question in no part
ut the labial appendages, and he imagined it
to be connected with the male generative func-
tion, of which he therefore conceived the parts
mentioned to be the organs. Itis obvious that
the ap seen by Ehrman was the undu-
lating motion of the cilia, which organs, how-
ever, he had not recognised. He makes no
mention of currents, and consequently could
not perceive the connexion of the phenomenon
with respiration, which was also less likely to
occur to him, as he supposed the motion to be
confined to the appendages mentioned.

The observations of Ehrman led Treviranus
to investigate the subject;* and he distin-
guished two different motions, the one a mus-
cular contraction, the other the peculiar motion
alluded to by Ehrman. The latter motion had
the appearance of a trembling or flickering
of innumerable points, and seemed at some
places as if suubuced by a moving fluid, and
at others by the agitation of oblong vibrating
organs. It was uliarly distinct alongside
each of the bars of the gills and appendages.
He farther perceived that the agitation on the
surface of these parts caused an eddying mo-
tion in the water in which they lay, and also
set in motion globules of blood which had
escaped from the vessels. On breaking down
the parts into small fragments, he found that
each retained its power of motion, by which
they moved in most manifold directions, the
larger masses at the same time contracting and
dilating themselves. From these observations
Treviranus concludes that the bivalve Mollusca
afford an example of a structure in which the
integrant parts possess an independent vitality.
Their independent vitality shews itself in the
persistence of their automatic motion after
solution of organic connexion with each other,
and this motion is intermediate in its nature
between the spontaneous movements of organic
molecules in infusions, the male semen, &c.
and the motion of muscular parts, which re-
quires the integrity of the texture and the
application of a stimulus. These reflections
on the relation of the phenomenon to the
general laws of organization are the sole infe-
rences which he draws from his observations.
He notices the motion of the water only as a
concomitant and subordinate circumstance, not
having been aware of its determinate direction,
its relation to the respiratory process, or, in
short, of its being the chief end and effect of
the motion of the cilia. :

The next researches on the subject are those
of Huschke, narrated in a paper in the Isis for
1826.+ Not having seen the original, we must
content ourselves with a brief notice of them to
be found in Burdach’s Physiologie.t It is there
stated that on detaching a portion of the gill
of the Fresh-water Mussel ( Unio pictorum),
Huschke found that the water “ moved up-

* Vermischte Schriften, Band iii. p. 234.
+ P.623. ,
¢ Band iv. p. 434,

625

wards on one side, and then in an eddying
manner back again.”

Raspail, in a memoir on a species of fresh-
water polype, published in 1828,* pointed out
the analogy between the phenomena exhibited
by the gills of Mollusca and those observed in
infusory animalcules and polypi.

Ciliary currents were now described by vari-
ous other writers of eminence, but their causes
were very commonly mistaken: among the
number may be quoted Poli,t Delle Chiaje,t
Carus,§ De Blainville,|| and Unger.{

Having observed currents produced in other
instances by an impelling power inherent in
the surfaces over which the fluid passed, I was
myself led to suspect that the respiratory cur-
rent in bivalve Mollusca was of the same kind,
or that it was caused by an impulsion commu-
nicated to the water by the surface of the gills
and other parts over which it was conveyed in
its passage, without being aware of any similar
view having been entertained by others. I
then observed the determinate direction of the
impulsion along the surface, together with the
arrangement and action of the cilia. These
observations were published at the time (1830)
in a paper already mentioned,** in which also
the respiratory currents of the bivalve Mollusca
are considered as a particular example of a
more generally prevailing phenomenon.

In a paper on the circulation of the blood,

“in Magendie’s Journal for 1831,++ there are

some remarks pertaining to the present subject,
from which it appears that the author, M.
Guillot, had observed the ciliary motion of the
gills of the Sea-mussel and Oyster. He has,
however, like Baker, mistaken the regular un-
dulations of the cilia for the circulation of a
fluid within vessels. He takes no notice of
any motion or current excited in the water.

Carus,{{ in a memoir on the development of
the River-mussel, states that he observed an
undulatory or oscillatory motion of the gills,
and that by this motion, which he conceives to
be in the substance of the gill, the water is
propelled, and the general respiratory current
through the branchial cavity produced. It is
obvious that what he calls an oscillation of the
substance of the gill, and which he erroneously
supposes has previously escaped attention, is
merely the undulatory motion of the cilia.

The last researches on this subject which we
have to notice are those of Purkinje and Va-
lentin.§§ As above stated, they discovered the
ciliary motion in the alimentary canal of the
Mollusca, having found it in the Lymnza, Pa-
ludina, and the Fresh-water mussel.

* Mémoires de la Soc. d’Hist. Nat. de Paris,
pe p- 131, seq. Chimie Organique, 1833,

+ Testacea utriusque Siciliz, t. i. 51.
_ ¥ Istituz. di Notom. e Fisiolog. comp. t. i. p. 278.
§ Lehrbuch der Zootomie.
Malacologie, 157.
Uber die Teichmuschel, p. 10.
** Edin. Med. and Surg. Journal, vol. xxxiv.
++ Tom. xi. p. 182.
tt Nova Acta Acad. Ces. Leop. xvi. p. 58, seq.
§§ Loc. cit.

626

Such isan outline of the observations hitherto
made relative to the ciliary motion in the
bivalve Mollusca. We may now shortly con-
sider those which refer to the other classes of
these animals.

Dr. Fleming,* in describing the cilia in
some species of Polypi, states that “ analo-
gous hairs” exist on the branchie of the Tri-
tonia, which may probably be considered as
forming part of the aerating organs. He
also mentions, in another place,+ that these
branchiz “ readily fall off, and, as if indepen-
dent, are capable of swimming about for a
short time in the water, by means of minute
hairs with which their surface is covered, and
which move rapidly, pushing forwards the
distal extremity.” Gruithuisen, as formerly
mentioned, observed the ciliary motion, and
recognised its true nature in the Valvata bran-
chiata, a species of fresh-water snail. Also
Raspail,t having seen the phenomena pro-
duced by the gills of the Fresh-water Mussel,
was led by analogy to discover the same in the
Lymneza and Paludina. Without being aware
of these previous researches, I observed the
ciliary motion in several different tribes of
marine Mollusca, and shewed that it prevailed
extensively among Mollusca generally. Mr.
Lister, as has been already stated, has subse-
quently discovered that it exists in the Ascidia ;
and since then I have also found it in that
animal, though in a different species.

9. Of the ciliary motion of the embryo of
Mollusca —The embryo of Mollusca exhibits,
while within the egg, a peculiar rotatory mo-
tion which belongs to the class of phenomena
we are here considering, and is referable to the
same cause. This motion has been observed
in the Gasteropodous and Bivalve Mollusca,
and may perhaps be found in others.

Gasteropoda.—_Swammerdam§ states that in -

examining the young of the viviparous water-
snail, while they were yet inclosed in the mem-
branes of the ovum, he observed the embryo
turning round in the contained fluid with con-
siderable rapidity, and, he adds, “ in a very
elegant manner.” He again mentions the fact
in another place.|| Baker observed the same
appearance in the ova of a fresh-water snail,
which appears to have been the common Lym-
nea. He says,§[ “ when the eggs are about a
week old, the embryo snail may be discerned
in its true shape, turning itself very frequently
within the fine fluid in which it lies.” These
brief notices of this remarkable fact by Swam-
merdam and Baker seem to have failed to ex-
cite the curiosity of succeeding naturalists, for
there would appear to be no account of any
subsequent researches on the subject till those
of Stiebel published in 1815,** who seems not

* Mem. of Wern. Soc. of Edin. iv. p. 488.
t Philosophy of Zoology, v. ii. p. 470.
t Loc. cit.
Biblia Nature, p. 142.
i Op. cit. p. 179.
_Of Microscopes, &c. vol. ii. p. 325, 329. -
** Diss. sist, Lymnei stagnalis anatomen, Goet-
ting, 1815, and Meckel’s Deutsches Archiv fiir die
Physiologie, Bd. i. p. 424, Bd, ii, p. 557.

CILIA.

to have been aware that the fact had been pre+
viously noticed. Stiebel’s observations were
made on the ova of the Lymnzus stagnalis.
They were followed by those of Hugi* in 1823,
and Carus in 1824,+ on the same species, to
which Carus afterwards} (in 1827) added cor-
responding observations on the Paludina vivi-
para. About the same time (1827) Dr. Grant
extended the inquiry to salt-water Gasteropoda,
both naked and testaceous, and, as far as I
know, was the first to point out the cilia, which
are very conspicuous in salt-water species, as
the agents which cause the rotation.

The eggs of the Lymnzus (or Lymnea) are
deposited in clusters, being imbedded in oblong
masses of gelatinous matter that are found ad-
hering to stones or Arpad gees Each egg
consists of an oval pellucid membrane, con-
taining within it the yolk surrounded by a con-
siderable quantity of limpid fluid. The yolk
is at first round, without any obvious distinc-
tion of parts, but in the progress of develop-
ment it changes its figure, and is gradually
converted into the embryo, of which the shell
and several principal organs can soon be dis-
tinguished. From the descriptions of the au-
thors above mentioned, as well as from some
observations made by myself, it appears that
the embryo is at first motionless, but that as
soon as the distinction can be perceived be-
tween the anterior or cephalic extremity and
the rest of the animal, its rotatory motion com-
mences. This invariably goes on in the man-
ner indicated by the larger arrows (c, ¢) in the
annexed figure, the head or anterior extremity

Fig. 307.

—

ij

Embryo of Lymnea.

continually receding. After a time the rota-
tion is combined with a progressive motion,
by which the embryo, while turning on its
axis, moves onwards at the same time along
the inside of the egg, performing a circuit like
a planet in its orbit. The path described by
a point on the surface is indicated by the spiral
line in the figure.

Stiebel, as well as the earlier observers men- —
tioned, is silent as to the cause of this curious —
phenomenon. Carus§ at first denominated it —
a primitive or cosmic motion, without clearly

* Isis, 1823, p. 213. “*
t+ Von den _aiissern Leben eeae der —
weiss-und kaltbltitigen Thiere. Leipz. 1824,
$ Nova Acta Acad. Cas. Leop. vol. xiii, p. 763.

§ Von den aiiss. Lebensb. p. al

CILIA.

explaining what he meant by the term. Havin
subsequently discovered that a current existe
in the fluid in an opposite direction to that
followed by the embryo, he ascribed the mo-
tion to an attraction and repulsion exerted by
the substance of the embryo on the surround-
ing fluid,* more especially at the region of the
body where the respiratory organ was afterwards
to be developed, and justly conceived that the
chief purpose served by it was to renew the
water on the respiring surface of the embryo.
The attraction and repulsion again he supposed
to be produced by an oscillatory motion which
he perceived on the surface of the embryo.
This oscillatory motion, although he describes
it as taking place in the substance of the animal,
seems to be. nothing else than the usual undu-
latory play of moving cilia, such as has been
already described in other instances,—indeed
he himself compares it to the undulation on
the armsof polypi. I have distinctly perceived
the cilia, though they are very small, in the
embryo of the small species of Lymnza com-
mon in this country. It is the one represented
in the figure, but considerably magnified. The
current takes place along the whole of the sur-
face indicated by the small arrows, which also
mark its direction, heing opposite to that in
which the embryo moves. The cilia, though
they probably exist over all this surface, were
distinctly seen only on the part inclosed be-
_ tween the dotted lines at a; it required a dou-
blet of one-thirty-fifth of an inch focus to make
them visible.

Appearances similar to those described were
discovered by Dr. Grant in the ova of Marine
Gasteropoda. In examining the embryos of
the Buccinum undatum and Purpura lapillus,
which are inclosed in groups within transparent
sacs, he was struck with a rapid and incessant

motion of the fluid in the sac towards the fore:

part of the embryo, and he cbserved that this
motion was produced by cilia placed around
two funnel-shaped projections on the fore part
of the young animal, which form the borders
of a cavity in which he perceived a constant
revolution of floating particles. He also ob-
served these circles of cilia in the young of
other testaceous Mollusca, as the Trochus,
Nerita, &c. in which the embryo was seen re-
volving round its axis. He met with the same
appearance in the naked Gasteropoda, as the
Doris, Eolis, &c. The embryo of these re-
volves round its centre, and swims rapidly
forward by means of its cilia, when it escapes
from the ovum. My own observations on the
ova of the Buccinum agree generally with those
of Dr. Grant. The larger cilia are placed
round the prominent border of a cavity on the
fore part of the body, but the surface of the
foot and other neighbouring parts is also ciliated,
though the cilia are there much smaller. Dr.
Grant assigns various uses to these motions ; it
seems not to have occurred to him that they
were connected with respiration, although there
can be little doubt that they are principally
subservient to that function.

* Nova Acta, xiii. p. 771.

627

Acephala.—The rotation of the embryo of
bivalves was discovered by Leeuwenhoek, and
described by him in one of his epistles, dated
October, 1695.* On examining the ova of a
species of Fresh-water Mussel with the micro-
scope, he observed the embryo turning slowly
round within the egg, like a sphere revolving
onits axis. This was at a time when the shell
could be distinctly perceived on the young
mussel ; he had failed in discovering the phe-
nomenon in some ova of the same species
which he had examined at an earlier period of
advancement.t He adds, that he was so much
delighted with the spectacle of the young Mus-
sels turning round within the egg, that he spent
two hours along with his daughter and his
draughtsman in contemplating it. Baster,}
who wrote in 1762, seems to have observed an
appearance of the same kind in the ova of the
Oyster, if we may judge from a reference by
Cavolini, for I have not been able to consult
the original. More recently (1827) Sir E.
Ifome and M. Bauer§ perceived the motion in
the embryo of the Fresh-water Mussel, as de-
scribed by Leeuwenhoek, but erroneously attri-
buted it to a small worm which pierces the
egg and preys on the young mussel, and which,
according to their view, by dragging on it pulls
it round in the manner described. Lastly,
Carus subjected the phenomenon to a more
careful investigation, in the course of his re-
searches on the development of the River Mus-
sel.|| According to his observations the em-
bryo, at the time the motion becomes percepti-
ble, has acquired a flattened triangular shape
(fig. 308), the two halves of the shell cover its
two surfaces, and are united
together by the hinge at the
base of the triangle. When
the ovum is placed under
the microscope, the embryo
is seen moving round in aho- ©
rizontal direction, as indica-
ted by the larger arrows, ap-
pearing as if it turned on the
centre of the lowermost shell.
When the embryo is extract-
ed from the egg, a current is perceived in the
water opposite that part where the current en-
ters and issues in the adult animal, (as shown
by the small arrow,) and Carus therefore attri-
butes its rotatory motion to an attraction and
repulsion exerted on the water by that part
of the embryo, which is afterwards to form
the respiratory organ. The attraction and re-
pulsion of the water he supposes to be pro-
duced by an oscillatory motion observable
in the substance of the animal at its surface, as
in the embryo of the snail, which motion, as we
have already seen, is in reality an undulatory
movement of minute cilia. As in the snail
also, he conceives the phenomenon to be con-
nected with respiration. Foran account of his

Embryo of Mussel.

* Ep. 95. Cont. Arc. Nat. 1697, p. 26, 27, in
Op. tom. ii.
+ Ibid. p. 20.
¢ Opuscula Subseciva, tom. ii. p. 146.
Phil. Trans. 1827, p. 39.
j Nov. Acta, xvi. p. 27, sqq,

628
observations on the velocity and direction of
the motion, and its supposed influence in de-
termining the figure of the animal, [ must refer
to the paper itself.

The analogy of these motions of the embryo
of the Mollusca with the phenomena exhibited
by the ova of Infusoria, Polypi, Sponges, and
Actiniw, already described, scarcely requires to
be pointed out. We shall afterwards see that
it extends to the ova of Batrachian Reptiles.*

11. Phenomena of the ciliary motion in the
Vertebrata.—tThe ciliary motion exists very ex-
tensively in vertebrated animals. Until lately
it had been found only in the larve of Batra-
chian Reptiles, but Purkinje and Valentint
have recently made the important discovery
that it exists also in adult Reptiles, Birds, and
Mammiferous animals; and it seems to prevail
generally throughout the three classes, having
been found by these naturalists in all the nume-
rous examples of each class examined by them
in the course of their investigations. It has
not been found in Fishes, though many species
have been submitted to examination.f

The parts of the body which exhibit the
ciliary motion in the Vertebrata are, the lining
membrane of the respiratory organs, and that of
the generative organs in the female. Besides
this general situation, it is found on the external
gills and surface of the body in the larve of
Batrachia, and on the surface of the embryo of
these reptiles while contained within the ovum.

A. Reptiles—The ciliary motion has been
discovered in all the orders of Reptiles. It has
been found in every species submitted to ex-
amination, and is therefore presumed to exist
in all.

Batrachian Reptiles. 1st. Larve and ova.
—The Batrachian Reptiles, while in the feetal
or larva state, breathe by means of gills or
branchiz, and it was on the gills of the young
Salamanderand Frog that the phenomenon under
consideration was first discovered as existing in
vertebrated animals. The gills of the young
Salamander might in appearance be compared
to feathers or pinnated leaves; there are three
on either side, each consisting of a main stem
bearing two rows of simple leaflets; they are

* In the preceding account of the ciliary motions
in the Invertebrata no mention has been made of
their existence in the class Crustacea: I think it
necessary to state that I have examined this class,
but without success; and since these pages have
been put into the printer’s hands I have re-exa-
mined the crab and lobster with the greatest care,
all the respiratory and alimentary surfaces, the
inner surface of bloodvessels, &c. with lenses of
all powers, but without finding the phenomenon. I
suspect the respiratory currents in Crustacea which
are produced by the motion of the branchie them-
selves, or of the plates or oars with which many
are provided in order to renew the water, have been
confounded with the currents produced by cilia,
more especially as many of the organs employed
for the purpose in the Crustacea are fringed with
long hairs; but I would scarcely reckon such mo-
tion as ciliary any more than those occasioned by
the gill-covers of a fish. 2 ;

+ Miiller’s Archiv. 1834. Edinb. New Philos.
Journal, xix. and Comm. Phys. de Phenomeno
motus vibratorii continui. Wratislav. 1835, 4to.

¢ See note at p. 29.

CILIA.

wholly external, projecting backwards and out-
wards from the side of the neck. The tadpole !
of the Frog (fig. 309) has at first gills resem-

Fig. 309.

bling those of the Salamander, but of a simpler
form; they are also three on each side, but have
each only five or six diverging branches. The
gills of the Salamander, although not perma-
nent, endure till the animal makes full use of
its lungs, but the external gills of the Frog are
of very short duration, being soon superseded
by internal gills, more resembling those of a
fish, with which the animal respires for the rest
of the larva state.

By means of the microscope the blood may
be seen circulating through the external gills of
the Frog and Salamander ; it passes outwards to
their extremities by the branchial arteries, and
returns in a contrary direction by the branchial
veins. The water also is moved continually
over these organs, for the purpose of respira-
tion, in a constant and determinate direction,
and this is effected by the peculiar impelling
power we are here considering, viz. the ciliary
motion on their surface.

Steinbuch,* a German naturalist already
mentioned, while examining the circulation of
the blood in the gills of the Salamander, ob-
served that small bodies floating in the water ;
were carried, as if by attraction, to the surface i
of the gill, and again repelled from it. He
also found that portions detached from the gill
moved themselves through the water, or if kept
fixed, continued as before to attract and repel
small objects in their vicinity. From these
and similar facts he was led to conclude that
the water was continually propelled over all
parts of the gill, that the current thus produced
served to renew the water in the process of re-
spiration, that the power producing the propul-
sion resided in the gill, and was exercised in-
dependently of the will of the animal; and
lastly, from the analogy of Infusoria and Polypi,
in which currents are produced by cilia, he im-
ferred that in this case also the water was pro-
bably impelled along the surface by the action
of cilia, though he could not actually perceive
any such organs. Steinbuch next examined —
the tadpole of the Frog, and found that its. ex-

ee ee ee ee ee eee

——

* Analekten neuer Beobachtungen und Untersuch- _
ungen fiir die Naturkunde, Furth, 1802. p- 46, e
$q4q- | :

CILIA.

ternal gills exhibited the same phenomena, but
he could discover nothing of the kind on the
internal gills.

Gruithuisen* observed in the tadpole of the
Green Frog that so soon as the circulation of the
blood began in any part of the gills, small ob-
jects were attracted and repelled from that spot,
and that the same took place a few days later
on the tail wherever vessels had been formed.
He conceived that the motion of the water was
for the purpose of exposing the blood to its in-
fluence, and compared it to the current pro-
duced by Infusoria by means of cilia. He does
not say, however, that he had seen cilia in the
tadpole.

uschket+ observed that the water in the

vicinity of the gills of the young Salamander
was thrown into a boiling-like motion, while it
flowed steadily at other parts of the body.

Without being aware of these previous disco-
veries, I was led in 1830, by an accidental ob-
servation of my own, to go over nearly the same
ground.t{ I had cut off one of the external
gills of the tadpole of the Frog, and placed it
with a drop of water under the microscope,
with the view of measuring the size of the glo-
bules of blood that might flow from it, and was
astonished to perceive that the globules, on
escaping from the cut part of the gill, moved
rapidly along its surface towards the points of
the branches in a constant and uniform manner.
On further inspection it soon became evident
that the blood-globules were entirely passive in
their motion, and that other light particles
brought near the gills were moved in a similar
manner; their motion being manifestly owing
toa current produced in the water along the
surface of the gill in a determinate direction.
A conclusive proof of this was afforded by put-
ting the gill which had been cut off, into a
watch-glass with a larger quantity of water. It
was then seen that when the gill happened to
be fixed by any obstacle, small bodies in its
vicinity were moved along it as before towards
the points of the branches, but when unim-
peded the gill itself advanced through the
water in a direction contrary to that in which
the particles were moved, the trunk being
turned forward; the tendency to produce a
current in one direction, thus causing the gill,
now no longer fixed, to move in the opposite
one. The current began at the root of the gill,
and ran along the branches, at the points of
which it did not continue its primitive direc-
tion, but turned off sideways, and immediately
ceased. (See fig.309, C).

I soon found that the gill was not the only

of the animal which excited motion in the

water. Nearly the whole surface of the body
produced the same effect. A general current
commenced on the fore part of the head, pro-
ceeded along the back and belly and the two

* Salzburg. Medicinisch-Chirurgische Zeitung,
1819, ii. p. 447.
+ Isis, 1826, p. 625, (cited in Burdach’s Physio-
logie, from which I quote, not having seen the ori-
inal.)
rr Edinb. Med, and Surg. Journal, xxxiv.

629

sides, to the tail, along which it continued to its
extremity. It was not so strong as that on the
gills, but agreed with it in other respects.

I continued for some time to observe the
phenomenon in the larva of the Frog, in order
to find out whether it underwent any alteration
in the progress of the developement of that
animal. It is known that after a.time the ex-
ternal gills become covered by a fold of the
skin, and inclosed in the same cavity with the
internal gills, when they gradually shrink and
at last disappear. On examining the animal
while this change was taking place, and for
some time after, it appeared that the external
gills after their inclosure still retained their
peculiar property, and continued to do so as
long as any portion of them remained; the
current on the body remained the same; on the
tail it acquired a twofold direction diverging
from the middle part or continuation of the
vertebral column, obliquely upwards and down-
wards towards the upper and lower edge. As
the animal a in growth, the currents
gradually disappeared over the greater part of
the surface, continuing longest at the posterior
part of the body; at length, when the pos-
terior extremities were so far advanced in
growth that the thigh, leg, and toes could be
discerned with a magnifying glass, which was
the latest period of observation, the current
existed only at the commencement of the tail,
and on a small part of the body near the hind
leg. The internal gills, though tried in various
stages of development, did not exhibit the
phenomenon.

I next sought for the same appearances in
the larva of the Newt or Water Salamander,
which was first examined a few days after its
exclusion from the egg when its gills are ve
simple. At this period the surface of the
animal produces currents agreeing in almost
every circumstance with those which take
place in the larva of the frog at a correspond-
ing stage of its development. Particles of
powder diffused in the water are carried alon
the surface of the body from before back-
wards; on the gills they are conveyed along
each of the trunks from the root to the ex-
tremity. The gills also, when cut off, move
through the water with the cut extremity for-
wards, in a direction contrary to the currents.
I have since found nearly the same phenomena
in the gills at a much later period.

It was evident that the purpose of these
currents was to effect a renewal of the water
on the respiratory surfaces; respiration in these
animals yeep | being performed not only by
means of the gills, but also by the general sur-
face of the body.

It appeared that the power of impelling the
water was wholly confined to the external sur-
face of the animal; a portion of the skin being
raised and ssothitied, floating bodies were
moved along its external surface only. Parts
cut off from the animal continued to excite
currents for several hours after their separation,
and the smallest portion produced that effect.
In these cases the current always moved in
the same direction relatively to the surface of

630.

the detached parts, as it had done previous to
their separation.

At the time of making these observations
I had not been able to detect Cilia in these
larve, although, from the analogy of the In-
vertebrata, I was led carefully to look for them.
Since then I have succeeded in perceiving
them with the aid of Wollaston’s doublet of
one-thirtyfifth of an inch focus, especially when
a jaa of the gill is compressed under a plate
of mica. They are to be distinguished chiefly
by their waving motion, which is so charac-
teristic as to remove all doubt of their ex-
istence; though here, as in other instances in
which they are very minute, it is not always
possible to demonstrate their existence by
actual observation on every spot of the sur-
face. eS

Ova of the Batrachia—In the course of
the above-mentioned observations, I was led
to enquire whether the phenomena in question
appeared at a still earlier stage. _With this
view I examined the ova of the Newt, which
for a considerable time may be procured in all
degrees of advancement, and found that the
ciliary motion presented itself in the embryo
a considerable time before its exclusion from
the egg. Since then I have observed the same
with regard to the embryo of the Frog.

In both cases the embryo is formed from
the yolk or opaque central part of the ovum,
by a series of changes sufficiently well known ;
it is surrounded by a clear fluid, which is
inclosed between it and the external pellucid
membrane of the egg. By means of a lens,
minute bodies may generally be perceived
floating in the fluid, which by their motion
serve to indicate the currents that take place
in it; but with a little care the embryo may
be extracted from the egg, and then the course
of the currents along its surface can be ren-
dered more evident by the usual means.
A (fig. 310) is an enlarged view of the embryo

Fig. 310.

Embryo of the Frog.

of the Frog at the earliest stage at which I have
detected the motion. The vertebral canal is
just closed, and at the fore part of the body
three ridges on each side indicate the com-
mencement of the gills. The arrows point out
the course of the currents. They proceeded
backwards along the dorsal surface, diverging
in a direction downwards and backwards on
the sides. They were visible but weaker on
the abdominal surface. B represents the em-
.bryo farther advanced, the currents have nearly
the same direction but are better marked, they
are strongest on the lateral eminences of the

CILIA. esas - ee

mon
head which correspond to the future gills.
In the embryo of the Newt, the phenomena
are in a great measure similar; the currents
seemed, however, to begin and to continue most
vigorous on the abdominal surface; they are
more particularly described in the paper re-
ferred to. ;
On extracting the embryo of the Frog, and
viewing its surface in profile with Wollaston’s:
doublet, moving cilia may be perceived on
various parts. They appear like a transparent
undulating line on the surface, and, though
very minute, are so distinct as to leave no doubt
of their existence. +
No one can fail to perceive the analogy
which subsists between the phenomena just
described, and those which occur in the ova
of Zoophytes and Mollusca. I have not been
able distinctly to perceive a rotation of the
embryo of the Batrachia, as observed in the
other instances, but Purkinje and Valentin
state that they have seen it, and Rusconi ob-
served that the embryo of the Frog, when
extracted from the ovum, turned round ina
certain direction, which motion he supposed
to be produced by water entering and issuing |
through pores in the skin.*
The phenomena in the Batrachian larve have :
since been observed by Miiller,t Raspail,{
and Purkinje and Valentin.§ The last men-
tioned naturalists also distinguished the cilia ’
and perceived the motion within the egg. q

fa, we
Sis ye a

i ate

Adult Batrachia.—The ciliary motion was
discovered in the adult Batrachia by Purkinje
and Valentin; indeed, it may not be improper
again to state that the discovery of the phe- 2
nomena in adu!t Reptiles generally, and in Birds
and Mammiferous animals, is due to these phy-
siologists.

According to their account, the ciliary mo-
tion in the Batrachia, as well as in all other
vertebrated animals in which they have dis-
covered it, occurs in two situations within
the body, viz. on the lining membrane of the
respiratory organs and on that of the genital
organs of the female. They state that it exists
over the whole internal surface of the lungs,
and in the nose, mouth, and pharynx, extend-
ing as far back in the throat as the glottis, but
no farther. They say nothing of the direction
of the impulsion. Again, in the female, they
discovered the motion on the internal surface
of the oviduct. The result of my own ex-
amination of the Newt, Frog, and Toad is
somewhat different. In all the three I found
the ciliary motion very distinct in the mouth,
throat, and gullet; in none could I perceive it —
in the lungs, notwithstanding very careful trials. —
In regard to the oviduct I have examined it ©
only in the Newt, and although I could per-—
ceive something like the motion on the edges
of its superior orifice, I could not detect it on
the internal surface of the tube.|| %

* Sur le Developpement de Ja Grenouille Com:

mune. Milan, 18 &. ee

+ Burdach’s Physiologie, Bd. iv. p. 434, —

t goes Organique, 1833, p. 250. if
Pp. cit. :

i Edin, New Phil. Journal, xix,

CILIA.

The ciliary motion in the mouth and throat
occurs all the way from the opening of the
mouth to the termination of the esophagus.
Its extent and the direction of the impulsion
are easily ascertained by means of powdered
charcoal; they are pointed out by the arrows
in the adjoining figures, A and B (fig. 311),

Fig. 311.

which are taken from the Newt, the ap-
pearances in the Frog and Toad being not ma-
terially different. a is the lower jaw detached
from the head, 6 the tongue, c the glottis,
d the esophagus cut off from the head (at g, g,
Jig. B), and laid open from above, e the sto-
mach, and f, f; the lungs. The general course
of the impulsion, or, if in this case we might
so express it, the currents, is longitudinal; they
begin at the symphysis of the lower jaw and
extend to the lower end of the cesophagus,
where they terminate abruptly at the entrance
of the stomach, thus differing from the de-
scription given by Purkinje and Valentin; but
it is worthy of notice that these observers de-
seribe the motion in the Tortoise and Serpent
as extending the whole length of the cesopha-

gus. At particular parts the impulsion fol-
lows the direction of the plaits of the lining
Membrane. Figure B represents the head and

the roof of the mouth, from which the lower
jaw has been separated. On this part of the
mouth also the general course is longitudinal,
from before backwards; at the nostrils h, A,
the particles are drawn in at one edge and issue
at the other, as indicated in the outline of
figure B.

As regards the use of the ciliary motion on
the internal membranes of the Batrachia, we
can scarcely doubt that one purpose is to
convey onwards the secretions of these mem-
branes in the direction indicated. It is not
impossible also that it may have some more
intimate connection with the respiratory pro-
cess; but on this point we have not as yet suf-
ficient grounds for forming a probable opinion.

Sauria, Ophidia, and Chelonia.—The authors
mentioned describe the appearances in these
reptiles as being similar to what they have

631

found in Batrachia. The ciliary motion oc-
curs in the oviduct and in the nose, mouth,
pharynx, Eustachian tube, and inner surface
of the lungs. In the Serpent and Tortoise they
state that it extends along the gullet to its
termination at the stomach, as we have seen to
be the case in the Batrachia. The motion of the
cilia is remarkably vivid in the mouth of the
Serpent, and in the Tortoise it endures for
several days after death, not ceasing till the
parts are destroyed by putrefaction. _

B. Birds— The same physiologists have
discovered the phenomena in thirteen species
of Birds, belonging to five different orders ;
and as they met with it in every species sub-
mitted to examination, they infer that it exists
in all.

In Birds, as in otherVertebrated animals, the
motion shows itself on the lining membrane
of the oviduct and that of the respiratory
organs. It was detected in the nasal cavities
and Eustachian tube, in the windpipe and its
divisions, even in the smallest branches capable
of investigation, and on the internal surface
of the large sacs or receptacles into which the
air penetrates. No trace of it could be found
in the mouth and pharynx. In regard. to the
direction of the impulsion, the authors state
that in the oviduct they had found it to be
from the internal towards the external extre-
mity of the tube, and in the windpipe from its
orifice towards its branches, or from without
inwards, at least they so observed it once in
the domestic Fowl. The phenomenon exists
in the foetus of the bird, having been distinctly
seen in the fcetal pigeon near the full period.

C. Mammalia.—<An accidental observation
led Purkinje and Valentin to discover the
ciliary motion in Mammalia, and they fol-
lowed out that discovery by extending their
inquiries to other vertebrated animals. While
examining the Fallopian tube of a rabbit that
had been recently impregnated, in order to
discover the ova, they chanced to observe
small portions of the mucous membrane of
the tube turning round, and moving briskly,
and recognized the appearance as an instance
of ciliary motion. The whole uterus and
organs of generation generally were then dili-
gently searched, and these motions were dis-
covered throughout their entire extent, though
bf very different degrees of intensity. in dif-
ferent places. They were particularly brisk in
the tubes, less so in the cornua of the uterus,
still less in the conjoined parts of the organ,
most lively of all on its swollen and dark red
lips, and of considerable strength in the vagina.
After finding the same appearances in the
oviduct of Birds and Reptiles, they succeeded
also in discovering it in the lining membrane
of the air-passages in all the three classes,
In Mammalia the ciliary motion of the re-
Spiratory organs occurs on the mucous mem-
brane of the nose and its sinuses, and that of
the Eustachian tube, also on the lining mem-
brane of the lower part of the larynx, the
trachea, and bronchial tubes, extending to
their smallest divisions capable of examination.
No trace of it can be found in the glottis, nor

632

in the mouth and pharynx. It was also sought
for unsuccessfully in the lachrymal passages.

The authors mentioned have now examined
it in twelve species of Mammalia, and have
found the same appearance in all of them;
they add that, although they have had no op-
onan of inspecting the parts in the human

dy so soon after death as to see the cilia in
motion, yet by covering the surfaces to be
examined with blood, which preserves the ap-
pearance longer than any other fluid, they
were able on examination, thirty hours after
death, satisfactorily to distinguish the cilia
both in the nose and windpipe.

I have seen the phenomena in the nose,
trachea, and Fallopian tubes of the Rabbit, and
in the trachea of the Dog.*

According to Purkinje and Valentin the
motion occurs in the uterine mucous mem-
brane, both in the impregnated and unimpreg-
nated state; but in gravid animals it appears
only on those parts of the uterus which are
not adherent to the chorion or external enve-
lope of the foetus. The direction of the impul-
sion they state to be from the internal ex-
tremity of the tube, towards the orifice of the
vagina. It seems wanting on the genital mem-
brane of young animals. On the other hand,
it occurs in the respiratory passages of the
foetus, it was detected in fetal calves and
lambs, and in fcetal pigs not more than two
inches long. The authors could not with cer-
tainty distinguish the direction of the im-
pulsion in the air-passages of Mammalia. In
some parts of the nose of the Rabbit, I have
been able to trace it clearly enough by means
of charcoal powder, the parts being placed in
tepid water. On the inferior turbinated bone
the grains of powder were slowly carried for-
wards, following the direction of the project-
ing lamine of the bone. On breaking open
the maxillary sinus and trying its lining mem-
brane in the same way, the impulsion seemed
to be directed towards the back part of the
cavity, where its opening is situated. By the
same means I traced the direction in the wind-
pipe of a young dog a few days old; the im-
pulsion was best marked on the posterior part
of the tube, and there it was obviously di-
rected towards the larynx, the direction being
thus different from what Purkinje and Valentin
observed in the domestic Fowl.

PART II.

1. Summary of the animals in which the
ciliary motion has been discovered.

From the foregoing facts it appears that the
ciliary motion is a phenomenon which prevails
most extensively in the animal kingdom, hav-
ing been found in the highest as well as the
lowest members of the Zoological scale.
Among Vertrebated Animals it has been dis-
covered in Mammalia, Birds, and Reptiles,
viz. the Batrachia, Sauria, Ophidia, and
Chelonia. Of the Invertebrata it has been
found in Mollusca, viz. Gasteropoda, Conchi-
Jferous acephala, and Tunicata ; in Aunelida,

* Edin. New Philos, Journal, xix.

CILIA.

viz. Aphrodita, Arenicola, and many Tubi-
colar worms, also in Planari@ and Naiades; in
Echinodermata, viz. the Asterias and Echinus ;
in Actinie ; in Meduse; in Polypi; in Sponges;
and in Infusoria. It is a remarkable fact tha
no trace of it has been observed in Fishes,
I at one time supposed that the pendent —
filaments of the gills of the foetal Skate and
Shark might probably be found to exhibit it;
but my friend, Dr. Allen Thomson, has care-
fully inspected those of the Skate without
being able to perceive any appearance of it.*
2. Organs or parts of the body in which the
ciliary motion has been ascertained to exist. ~
These may be referred to four heads, viz.
the skin or surface of the body, the respiratory,
alimentary, and reproductive systems. Its use
in all these cases, or the function in general of
the cilia, is to convey fluids or other matters
along the surface on which the cilia are placed,
or, as in the Infusoria, to carry the entire
animal through the fluid.
a. Surface of the body.—Cilia have been
found on different parts of the external surface,
in Batrachian larve, in Mollusca, Annelida,
Echinodermata, <Actinie, Meduse, Polypi,
and Infusoria. Their function in this situation
is various ; in most cases it is evidently respi-
ratory, but in many instances it is also locomo-
tive, as in Infusoria and Medusz, or prehensile,
as in Infusoria and Polypi; and perhaps it is
in some animals subservient to the sense of
touch or smelling, as may be conjectured with
regard to the cilia on the tentacula of some
Mollusca.
b. Respiratory system.—The ciliary motion
has been observed on the lining membrane of
the air-passages of Mammalia, Birds, and Rep-
tiles; and there, whatever may be its other
uses, it at least serves to convey the secretions
along the membranes, together with foreign }
matters, if any are present. It exists also on
the external gills of Batrachian larve, andon
the gills of Mollusca and Annelida. In other
Annelida, in Echinodermata and Actinic, it
is found on the external surface of the viscera
and on the parietes of the cavity containing
them, to which cavity the water has access.
The pores and canals of the Sponge are pro-
bably both respiratory and alimentary passages,
and under this head we must refer again to the
cilia on the external surface of Medusz, Polypi,
and Infusoria, as belonging partly to the respi-
ratory system. The use of the ciliary motion —
on the respiratory organs of animals with
aquatic respiration is obviously to renew the —
water on the respiring surface. oa
c. Alimentary system.—-The motion occurs —
in the mouth, throat, and gullet of Reptiles,
in the entire alimentary canal of Mollusca, on

* Since the above was written, a short not
has appeared in ‘‘1’Institut” of 16th Decembe:
1835, of the Transactions of the Leopoldine A‘
demy for 1834-35, from which it appears that F
kinje and Valentin have at last succeeded in dete
ing the phenomenon in Fishes, ‘They foun

the organ of smelling and the internal ¢
organs of the female. No further particulars
stated.

om i

CILIA.

the internal surface of the intestine and cecal
appendages of the Aphrodita, within the sto-
mach and ceca of the Asterias, in the stomach
of the Actinia, in the canals of the Sponge,
which no doubt belong partly to the alimentary
system, and in the mouth, throat, stomach, and
intestine of several Polypi. It is not easy to
see the purpose of the motion in all these
cases. In some it may merely convey secreted
matters along the surface of the lining mem-
brane; in Polypi it agitates the food within the
alimentary cavity, and in several instances it
seems almost to serve in place of ordinary
deglutition, to carry food into the stomach.

d. Reproductive organs.—The phenomenon
occurs on the mucous membrane of the Fallo-
pian tubes, uterus, and vagina of Mammalia,and
of the oviduct in Birds and Reptiles. From
the direction, of the impulsion being from
within outwards, it is difficult in the meantime
to assign any other office to the cilia in this
Situation than that of conveying outwards the
secretion of the membrane, unless we suppose
that it also brings down the ovum.

The phenomenon has been sought for in
other parts of the body, but hitherto without
success. Purkinje and Valentin state that on
examination they could not find it in the fol-
Jowing parts of vertebrated animals, viz. the
skin, serous membrane, the alimentary canal,
(except the mouth and gullet of Reptiles,) the
gall-bladder, the biliary and pancreatic ducts, the
urinary organs, the seminal vesicles and ducts,
Ahe conjunctiva, cornea, and iris, the internal

Surface of the bloodvessels, the globules of

the blood and lymph, the chorion, amnion,
allantois, and yolk-sac of Birds. I have also
wepeatedly examined the fatal membranes: of
athe common Fowl, and with the same result.
8. Of the ciliary motion in the embryo.—
According to Purkinje and Valentin the ciliary
motion of the genital mucous membrane does
mot appear in the feetus, nor until the animals
hhave made some approach to the adult state ;
that of the respiratory passages on the other

hand becomes apparent in the embryo long

hefore it attains maturity. The ciliary motion,
however, to which we would here refer is that
which occurs ata much earlier period on the
surface of the embryo of many animals, and
enerally causes it to perform a rotatory move-
‘ment within the ovum. It has now been ob-
served in the ova of Batrachia, Mollusca, Ac-
tinie, Polypi, Sponges, and Infusoria. While
the embryo is contained within the ovum, the
cilia produce a current in a certain direction
along its surface, or cause the whole embryo
to move in the opposite direction; hence the
‘very remarkable rotatory motion which eccurs
in many instances, and which is so well marked
an the Snail. When it has escaped from the
egg, the embryo moves about in the water by
a@™@eans of the cilia, as happens also with the

-maked gemmules of the Sponge after they are

1 from the parent. The ciliary mo-
‘tion jis subservient to the respiration of the
embryo, by renewing the contact of the water
or fluid contained .in the egg.on the respiring

‘Surface, and in some instances, the Mollusca

VOL, I.

633

for example, the motion is observed to be
especially strong at the part where the respira-
tory organ is afterwards developed. When the
embryo quits the egg, the cilia serve also for
locomotion, and by this provision the gem-
mules of fixed zoophytes are disseminated, and
conyeyed to situations suitable for their future
growth.

4. Figure, structure, and arrangement of
the cilia in general.—The cilia are best seen
when their motion slackens ; their shape, size,

arrangement, and manner of moving may then

be distinguished with tolerable accuracy, at
least in the larger sort. Their figure is in
general that of slender, conical, or sometimes
slightly flattened filaments, broader at the base
or root, and tapering gradually to the point.
Their size differs greatly on different parts even
of the same animal, but on corresponding
parts of different individuals of the same
species their size seems to be the same. The
largest I have measured are those on the point
or angle of the branchial lamine in the Buc-
cinum undatum; they are at least ;}, of an inch
long. I have not attempted to determine the
exact size of the smallest, but Purkinje and
Valentin state it at 0.000075 of an inch, while
they make the largest they have met with only
0.000908 in., which is considerably less than I
have found them; but they had no opportunity
of examining marine animals, in which, gene-
rally speaking, the largest cilia are met with.
In the Sea-mussel the darker-coloured cilia are ©
about 45) of an inch long, the others consider-
ably less.

The cilia are very generally arranged in re-
gular order. In some cases they are placed in
straight rows, as-on the gills of the Mussel; in
others they form circles or spiral lines, as in
many Infusoria; and Purkinje and Valentin
state that in animals of the higher orders the

. most prevalent mode of arrangement is in spiral

lines or ridges. They are generally set close
together in the same row; on the gills of the
Sea-mussel I find there are seven or eight of the
larger cilia in the length of 4),, of an inch, or
about seven or eight thousand io the length of
an inch, but in other cases there are many
more. In some instances they are erect, or at
right angles to the surface on which they are
planted, in others inclined, and then it would
seem that the inclination is in the direction of
the currents which they produce. In some
parts they are straight, in others curved, not
only when in action, but also when at rest, and
the points are bent in the same direction in
which the currents flow.

The substance of the cilia is transparent, and
for the most part colourless; in some, however,
it is coloured brown or yellowish brown. It
appears as if homogeneous, even when highly
magnified, and no fibres or globules are distin-
guishable init. It seems to vary somewhat in
consistency, for the cilia on some parts appear
extremely soft and pliant, and on others com-
paratively firm and elastic, though still abun-
dantly flexible. di

There is a peculiarity in the form of the cilia
in some animals, of which the Beroé end other

2T

‘634
‘Ciliograde Meduse afford a gootl example. In
these, in place of cilia of the usual form and
arrangement, there are rows of broad flattened
organs, each of which is made up of several
simple filaments joined together by a common
base, according to Eschscholz, or according to
Dr. Grant by a connecting membrane in their
whole length. The entire organ is raised or
depressed at once, so that the filaments are all
moved simultaneously, like the eye-lashes. The
compound cilia in some of the Rotatoria, de-
scribed by Ehrenberg, are probably of the same
nature.

5. Of the appearance of the cilia in motion.
—QOn examining these organs with a lens of
7; inch focus, when their motion is not very
rapid, the manner in which the individual cilia
move may be distinguished with tolerable cer-
tainty. Most commonly they have a fanning
or lashing motion, that is, the cilium is bent in
one direction and returns again to its original
state. The flexion takes place chiefly at the
base or root, but not wholly there, for. the
rest of the organ is obviously bent and altered
in’ figure; nay, the more elastic cilia, when
their motion abates in intensity, appear some-
times to bend only near the point, the base
and adjoining part remaining motionless.

When a number of cilia are affected in suc-
cession with this motion, the appearance of a
progressive wave is produced, and as in such a
case they are again and again moved in the
same way at very short intervals, successive
waves proceed along them in the same direc-
tion, which might be compared to those pro-
duced by the wind in a corn-field. Such at
least seems to be the true explanation of the
undulatory motion which so often occurs,
although it must be confessed that the motion
of the cilia individually cannot be distinctly
seen when the undulation is most perfect. The
undulations succeed one another along a range
of cilia with great regularity, and except in
the Rotifera, and perhaps some other Infusoria,
they seem always to maintain the same direc-
tion in the same parts.

Purkinje and Valentin describe the motion
of the individual! cilia as being more frequently
rotatory, or, as they term it, infundibuliform ;
and Ehrenberg states this to be the common
mode in the Infusoria; the cilium describing a
circle with its point, while the base is the centre
of motion. From my own observation, how-

_ever, I would be inclined to infer that this
motion is by no means the most common.

6. Duration of the ciliary motion after death
and in separated parts——The continuance of
the ciliary motion for some time after death,
and the perfect regularity with which it goes on
in parts separated from the rest of the body, are
facts which have been already repeatedly stated,
and sufficiently prove that the motion is quite
independent of the will of the animal, and also
that it is not immediately influenced by the
circulation of the blood, even in the respiratory
prgans. — .

The time -which it continues after death
differs in different species of animals, and also,
‘but in a much smaller degree, in different parts

CILIA.

.
&

of the same animal. Its duration is influenced —
also by the temperature of the air, and by the-
nature of the fluid in contact with the surface.
In Mammaliaand Birds the period varies from”
half an hour to four hours, being longer in
summer than in winter; but it is still further
pola when the parts are covered with

lood. In the gills of Batrachian larve I have ~
seen the motion continue six hours; but of all
vertebrated animals it is most enduring in the
Tortoise, in which animal Purkinje and Valen-
tin affirm they observed it fifteen days after
death, when putrefaction was far advanced ;
the irritability of the muscles remained in the
same animal for seven days. Among the in-
vertebrata the River-mussel affords an instance
of the great pertinacity of the motion, which
ceases only when putrefaction has advanced so
far as actually to destroy and dissolve the
tissues.

7. Effects of external agents on the ciliary
motion.— Steinbuch, Purkinje, and Valentin
allege that on touching the parts, or giving
them a gentle shock by merely striking against
the object plate of the microscope, the motion
is rendered brisker when it has become languid,
or is even renewed in parts where it has ceased.
They, however, attribute more importance to
this fact than it seems to deserve ; for it may be
doubted whether the concussion in renewing
the vivacity of the cilia does not act merely by
removing obstacles which impede their play.

Electricity and galvanism produce no visible
effect. A powerful discharge from a Leyden
jar was made to pass through the River-mussel
by Purkinje and Valentin without-causing any
change in the ciliary motion. Portions of the
external gills of the Tadpole were subjected by
myself to the same experiment and with a
similar result, except when the surface. was
abraded, which occasionally happened with a
strong discharge. I have exposed portions of
the gill of the River-mussel while viewed with’
the microscope, to the influence of a’galvanie
battery of twenty-five pairs of three-inch square
plates, charged with solution of salt, without
being able to perceive the slightest effect on the
motion of the cilia. The authors above men-
tioned obtained a similar result, both in the
Mussel and the domestic Fowl. :

The effect of. temperature is different in warm’
and cold-blooded animals. In the former, ac-
cording to Purkinje and Valentin, the motion’ —
stopped on exposure to a temperature of 43° F,
while it went on at 54° F. On the other hand
they found that in the Fresh-water Mussel it was
not affected at 32° F.; and I found the same ~
to be true of the Tadpole. A portion of the —
gills of the River-mussel, which [ kept for five
minutes in water at 969 F. shewed no change.’

Acids, saline solutions, and other substances
applied to the parts, differ in their effects ae:
cording to the kind of animals submitted
experiment. Thus, for example, fresh wai
instantly arrests the motion in the Marine M
lusca, and also in other marine animals”
which I have tried its effect, though as
rated solution of sea-salt destroys it botl
salt and fresh-water species. Purkinje

on

CILIA.

Valentin state the effects which they found to
result from the application of various sub-
stances, but erroneously conceiving, from some
preliminary trials, that the same substance
produced the same effect in all animals, they
confined their experiments to the Fresh-water
Mussel. According to their experiments,which
were made with a great many different sub-
stances, most of the common acid, alkaline,
and saline solutions, when concentrated, arrest
the motion instantaneously; dilution, to a
degree varying in different substances, pre-
vents this effect altogether, and a less degree
of dilution delays it. The same is the case
with alcohol, ether, aqua laurocerasi, sugar,
and empyreumatic oil. Kreosote, muriate of
baryta, sulphate of quinine, infusio pyrethri,
and muriate of veratria, act less intensely. Hy-
drocyanic acid and watery solutions or in-
fusions of belladonna, opium, capsicum, ca-
techu, aloes, musk, gum-arabic, acetate of
morphia, and nitrate of strychnia, produce no
effect whatever. They accordingly infer that
the substances affect the motion only in so far
as they act chemically on the tissue.

The result of my own experiments differs
from theirs in some points. In the River-mus-
sel I found that hydrocyanic acid, containing
ten per cent. of pure acid, invariably destroyed
the motion. Solution of muriate of morphia,
of medicinal strength, also arrested the motion
in the Mussel, but not in the Batrachian larve.
The motion on the gills of these larve also
continues unimpaired in water deprived of air
by boiling, or distilled, or impregnated with
carbonic acid; a sufficient proof, it may be
remarked, that it is independent of the che-
mical process of respiration.

In regard to the effect of animal fluids, the
authors already mentioned state that bile ar-
rests the motion, while blood has the property
of preserving it much beyond the time that it
lasts in other circumstances, at least in verte-
brated animals; thus it continued three days
in a portion of the windpipe of the Rabbit,
which had been kept in blood. But it is sin-
gular that blood or serum, whether of Quadru-
peds, Birds, or Reptiles, has quite the opposite
effect on the cilia of invertebrated animals,
arresting their motion almost instantaneously.
Albumen and milk also possess the conserva-
tive property, though in a less degree.

8. Effects of inflammation.— Purkinje and
Valentin excited inflammation artificially in
the nose and vagina of rabbits, and are in-
elined to conclude from their experiments,
which however are not numerous, that inflam-
mation arrests the motion.

9. Of the power by which the cilia are
moved.—It may next be inquired by what
means or by what power the cilia are moved ;
and, in particular, whether their motion, like
other visible movements in the animal body,
is effected by muscular action.

_ Dr. Grant,* reflecting that in the Berée a
vessel conveying water runs beneath each row

* Trans. of Zoological Society of London,
vol, i. p. ll.

635
of cilia, and that, according to M. Audouin,
in an allied genus of animals the water enters
the cilia, is disposed to liken the motion of
the cilia to that of the feet of the Echinoder-
mata. He seems accordingly to think it pro-
bable that the cilia are tubular organs, which
are distended and protruded by the injection
of water into them from elastic tubes running
along their base, in which the water is conveyed
by successive undulations. F

This view, however, seems scarcely recon-
cilable with the fact that the motion of the
cilia continues in parts separated from. their
connexion with the rest of the body, portions
so small that not more than two or three cilia.
are attached to them,.and in which the ope-
ration of the supposed undulating tubes can
scarcely be conceived. :

Ehrenberg states that in the Infusoria he
observed that the cilia were bulbous at. the
root, and that they were moved by small mus-
cles attached to the bulb. Purkinje and Va-
lentin also admit the existence of a bulb, and
they conceive it likely that the cilia are moved
either by muscular substance placed within.
the bulb, or by certain fibres which they be-
lieve they have discovered in the adjacent
tissue. ‘They describe these fibres as existing
in the substance of the membranes or other
parts supporting the cilia, being situated at
the surface, straight and parallel, and ap-.
pearing to be connected together by delicate
cellular tissue; and they think it highly pro-
bable that they are of a muscular nature.

The whole phenomena of the ciliary motion
seem to me most consistent with the notion
that it is produced by muscular action. I
must confess, however, that I have never seen
the muscular fibres described, nor the bulbs;
and perhaps the cilia are not moved merely
by muscular fibres attached to their base, like
the whiskers of the seal and cat, but may con-
tain muscular substance throughout a greater
or less portion of their length, by which. they
can be bent and extended; or perhaps they
may in some instances be bent by muscular
fibres, and resume their original shape and
position by virtue of their elasticity.

We need not hesitate to admit that the
ciliary motion is the result of muscular action
on account of the smallness of the muscular
apparatus necessary; for the researches of
Ehrenberg on the Infusoria have brought to
light examples of complex organization on as
minute a scale as any here required. Nor
need we hesitate on account of the great ra-

‘pidity of action; for there are familiar instances

of muscular motions of equal velocity. The.
continuance of the ciliary motion after death
and in parts detached from the rest of the
body, and its regularity in these circumstances,
are appearances, startling at first, but which,
though they differ in degree, may be fairly
compared with those produced in similar cir-
cumstances by involuntary muscular action,
and may be attributed to the same cause.
Thus the different parts of the heart, which
during life contract in a certain order inde-
pendently of the will, continue to act in the,
, aE 2 ea

636
same regular order for a time, and in some
animals for a long time, after death or sepa-
ration from the body; and it is remarkable,
although perhaps we are not warranted by ob-
Servation to lay it down as a general rule, that
there is a correspondence in the duration of the
ciliary motion after death and the persistence
of muscular irritability. In the Tortoise, for
instance, in which it is well known that the irri-
tability of the heart and other muscles endures
remarkably long after death, the ciliary motion
is also of extremely long continuance ; while
in Mammalia and Birds, the ciliary motion and
muscular irritability are both comparatively
‘soon extinguished.

On the whole, therefore, without laying any
Stress on the alleged discovery of a muscular
apparatus by Ehrenberg and the other authors
mentioned, we may venture to conclude that
the facts known respecting the motion of the
cilia are all reconcilable with the opinion that
it is produced by muscular contractility.

10. Strange as it may seem, after what has
been said, some observers maintain that the
cilia have no real existence, even in cases
where the appearance of them is the most
perfect, and that the whole is an optical de-
ception. [I allude particularly to Raspail ;
according to him the water which quits the
respiring surfaces has, in consequence of the
change produced in it by respiration, acquired
a different density, and consequently a dif-
ferent refractive power from the surrounding
fluid; it therefore produces the appearance
of lines or streaks at the surface of the parts,
which streaks are the supposed cilia. It is
scarcely necessary to repeat that the cilia are
seen when at rest, when all motion of the
water has ceased, and that they are evident in
circumstances in which no interchange of ma-
terials can take place between the tissue and
‘the water in contact with it; and indeed, after
the details already given, it is needless to say
more in refutation of this view.

11. Of the motion caused in fluids by the
cilia.—One of the most remarkable characters
‘of the motion produced in water and other
fluids by the ciliary action, is its definite di-
rection, which, except in some of the Infusoria,
‘appears to be always the same in the same
parts; at least I have never been able to per-
ceive any exception to this rule. dt pear
would rather lead to the belief that in the
Tnfusoria the motion of the cilia is under the
influence of the will, which would account for

this and other possible cases of exception.

We have hitherto taken it for granted that
the currents in the water are owing to the
mechanical effect of the moving cilia, without
formally adducing proofs in support of the
pinion; but at the same time the details
dicatly given must have served as such. The
currents cease when the motion of the cilia
stops, they are strong and rapid when it is
brisk, and feeble when it languishes; and
though there are modifying circumstances or
“perhaps exceptions, yet in general the mag-
nitude and velocity of the current seem to be

proportionate to the size and activity of the

CILIA.

cilia. It is true that while doubts remained
as to the existence of cilia in several well-
marked instances where the water unequivo-
cally received its motion from the surface over
which it flowed, and, independently of any
visible contractions of the animal tissue, there
was also considerable room to doubt whether,
even in the cases where cilia were manifest,
the effect of these organs was wholly mecha-
nical, and whether the motion of the water
was not rather due to some peculiar impulsive
power in the tissue, differing from mechanical
action. But more extended observation has
almost wholly removed these exceptions, while
it has considerably increased the number
of conforming instances, insomuch that there
seems at present no necessity for having re-
course to any other explanation of the motion
of the flnids than that it is produced by the
action of the cilia, and that their action is the
result of muscular contractility, a known pro-
perty of animal tissues.

The phenomena of the ciliaty motion séem
therefore of themselves to afford no counte-
nance to the notion of a peculiar impelling
power of the animal tissue, in Virtue of which
fluids are visibly moved along its surface, in-
dependently of impulse communicated to them
mechanically by cilia or by contraction of in-
closing solids; nor am I aware of other facts
which either alone, or viewed in connexion
with the former, warrant such a notion. But
as some physiologists believe in the existence
of such a power, and found their opinion, at
least partly, on alleged examples of visible
motions of fluids in organized bodies, pro-
duced without cilia and independent of con-
traction of the solids, it may not be amiss here
shortly to consider the principal facts which
have been adduced as instances of this kind.

First, Three cases have been already men-
tioned in which currents, more or less re-
sembling those produced by cilia, take place
on surfaces on which cilia have not been de-
tected; these are the currents in the Sponge,
those of the Tubularia indivisa, and those
within the stem and branches of Sertularie.
In regard to the Sponge, it is true that cilia have
been diligently sought for and without success;
still, considering the difficulty of the investi-
gation, it is not impossible they may exist in
some part of the passages through which the —
water runs, though not yet discovered, ape
cially as the ova possess evident cilia. With —
respect to the currents described by Mr. Lister
within the stem of the Tubularia, it will be —
seen, on referring to the account of these, that —
farther observations would be required to settle
the points here in question, viz. whether the
floating particles receive their impulse from the
surface over which they move independent
of any contraction of the stem, and whether or
not that surface is covered with cilia. To de-
cide these points satisfactorily it would 1
necessary to lay open the tube and make tr
of detached portions of the tissue as in ot
instances. The same remark is in a
measure applicable to the currents in the sfem
and branches of Sertularie, Indeed both

= Sy

CILIA.

instances have been described above only be-
cause of their seeming analogy with the rest,
but further investigation is still required to
determine their true nature. Neither these,
therefore, nor the Sponge afford uneqnivocal
examples of the peculiar motion of fluids al-
Inded to taking place independently of cilia.
Of course we may pass over without notice
the cases in which the appearance of the
‘moving cilia has been mistaken for a circu-

y, It is well known that in cold-
blooded animals the blood continues to move
in the capillary vessels for some time after the
heart has been cut out. This motion for the
_- most part goes on at first steadily from the
smaller to the larger vessels in the arteries
as well as the veins, and afterwards becomes
oscillatory. fHlaller, who particularly investi-
gated the phenomenon, was of opinion that it
could not be attributed to contraction of the
large vessels, to gravitation, nor to capillarity;
he therefore attributed it to some unknown
power which he conceived to be exerted by the
solid tissues on the blood and also by the glo-
bules of blood on each other, and to this
er, until farther investigation should eluci-
te its nature, he gave the name of attraction.
The same opinion or a modification of it has
been taken up by succeeding physiologists ;
accordingly many maintain the existence of a
peculiar propulsive power in the coats of the
ipillary vessels different from contractility, or
tbat the poboles of blood are possessed of the
wer of spontaneous motion. Among others,
- Alison has adopted and extended this view
in so far as he regards the motion of the blood
in the capillaries as one of the effects produced
by what he calls vital attraction and repulsion,
wers which he conceives to be general attri-
_ butes of living matter, or at least to manifest
_ themselves in other processes of the living
_ economy besides the capillary circulation.
| The motion in question has certainly not
_ been as yet satisfactorily accounted for by re-
ferring it to the operation of known causes.
At the same time we can scarcely admit that
the influence of such causes has been wholly
avoided in the experiments in which the phe-
nomenon has heen observed. It is not im-
_ possible, for example, that a certain degree of
_ agitation may be occasioned in the blood by
the elastic resilience of the vessels reacting on
_ it, after the distending force of the heart has been
withdrawn. The necessity of the case there-
fore, though great, seems scarcely such as alone
to warrant the assumption of a peculiar attrac
__ tive or repulsive power acting on the blood at
_gensible distances, of whose existence in the
animal! economy we have as yet no other evi-
dence. It may be remarked, finally, in regard
to the phenomenon alluded to, that it cannot
erly be termed a continuance of the circu-
con or the blood does not necessarily pre-

* As by Baker, Guillot, and others,

+4
é
=
Ss
.-
|

637

serve its original course, nor indeed any con-
stant direction. (See CrxcuLation.)

Thirdly, In several plants motions have been
observed in the fluids which are contained in
their cells or vesse!s in determinate directions,
and seemingly independent of any contraction
of the parietes of the containing cavities.. ‘Fhe
best known example of this is in the Chara.
Its jointed stem consists of a series of elon-
gated cells, which contain a clear fluid with
globules suspended in it. The globules are
moved up one side of the cel! and down the
other in continual circuit. No contraction can
be perceived in the parietes of the ce!!s, which
are indeed of a rigid texture, and this myste-
rious movement has therefore been ascribed to
some unknown and invisible impelling power.
It is doubtful, however, whether the motion
can go on unless the cell is entire, the experi-
ments of different observers on tuis point being
contradictory, and it certainly has never been
shewn that separated portions of the tissue
continue to excite the motion. In this state of
knowledge on the subject we can scarcely
admit this or similar motions of vegetable
juices as unequivocal examples of the opera-
tion of an impulsive power of the kind referred
to; and even on the contrary supposition it
does not follow that such a power exists in
animals.

On the whole therefore, from what has been
said regarding the several examples adduced,
we may conclude that they do not afford une-
quivocal evidence of visible motions being
produced in fluids in the animal body, inde-
pendently of contractions of containing solids
or of the action of cilia; and, consequently,
that viewed in reference to the ciliary motion,
they form no adequate reason for doubting that
the fluid is moved mechanically by cilia.

I may conclude this article by observing,
that though the general existence of the ciliary
motion in the Animal Kingdom is already suffi-
ciently established, yet many particular in-
stances of it must still remain to be found out,
especially in invertebrated animals ; and who-
ever has opportunities and inclination to cul-
tivate this field of inquiry will find his labour
rewarded by much curious and interesting
discovery.

BIBLIOGRAPHY.—( The works more especially de-
serving of attention are marked with an asterisk. )—
* Ant. de Heide, Anatome mytuli, &c. 8vo. Amst,
1684. Swammerdam, Biblia Nature, fol. Leide,
1737. *Leeuwenhoek, Opera, 4to. Delph. et Lugd.
Bat. 1695-1719. *Baker, Of microscopes, &c.
8vo. Lond. 1785. Hales, Haemastaticks, 3d edit.
8vo. Lond. 1769 LEliis, Hist. Nat. des Corallines,
4to. La Haye, 1756, (a translation from the Eng.
lish, with the'author’s additions). Rogsel. Insecten-
belustigungen, vol. iii. 4to. Niirnberg, 1755. *Spal-
lanzani, Opuscules de Physique, 8vo. Pavie, 1787,
*0O. F. Miiller, Hist. vermium terrestrium et filuvia-
tilium, 4to, Hafniz, 1773, and, Animalcula Iniu-
soria, 4to, Hafniz, 1786. *Cuvolini, Memorie per
servire alla storia dei polipi marini, 4to. Napoli,
1785; translated into German by W. Sprengel,
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fol, Parme, 1792. Stiebel, Lymnzi Stagnalis
anatome, 4to. Gott. 1815, and in Meckel’s Deutsches
Archiy, fiiy die Physiologie, Bd i. andii, Ehrman,

638

in Abhandl. der konigl. Akad. der Wissensch. zu
Berlin fiir 1816-1817. *Gruithuisen, in Salzb. Med.
Chir. Zeitung, 1818, Bd iv.; Nov. Act. Acad.
Ces. Leop. vol. x. G.R. Treviranus, Vermischte
Schriften, 4to. Bd iii. Bremen, 1820. Hugi, in
“Tsis for 1823. *Carus, Von den aussern Lebens-
bedingungen der weiss-und kaltbluetigen Thiere,
~4to. Leipz. 1824; Nov. Act. Ac. Cxs. Leop.
vols. xiii. and xvi. Fleming, in Mem. of Wer-
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1826. *R. Grant, in Edin. Phil. Journal, Edin.
. New Phil. Journ., Edin. Journal of Science, and
Trans. of Zoological Society. Sir E. Home, Phil.
Trans. 1827. * il, Mém. de la Soc. d’Hist.
Nat. de Paris, 4to. vol. iv. 1827; Chimie Or-
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E. H. Weber, in Meckel’s Archiv. 1828. Fr. Esch-
scholz, System der Acalephen, 4to. Berlin, 1829.
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*W. Sharpey, in Edin. Med. and Surg. Journal,
vol. xxxiv. July, 1830. Gwillot, in Magendie
Journal de Physiologie, xi. 1831. *Ehrenberg,
Ueber Infnsorien, in Abhandl. der k. Acad. der
Wissensch. zu Berlin fiir 1830 and 1831, Miiller’s
Archiv. i. 1834. R. Wagner, Isis for 1832. Jo.
Miiller, Handbuch der Physiologie, Bd i. 8vo.
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Bd i. 1833. *Jos. J. Lister, in Phil. Trans. 1834.
*J. E. Purkinje & G. Valentin, in Miiller’s Archiv.
Bd i. translated in Dublin Journ. of Med. and
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1835, (the only systematic treatise on the subject. )

( W. Sharpey.)
CIRCULATION (in Physiology), ( Circu-

latio, Circulus, Circuitus Sanguinis ; Fr. Cir-
culation du Sang; Germ. Blutlauf'; Ital. Cir-
colazione del Sangue;) designates in its more
extensive signification the course through or-
ganised beings of their nutritious fluid; as
limited to man and the higher orders of ani-
mals, the course of the blood from the heart
to the most minute vessels, and from these back
to the heart.

By modern writers on physiology the circu-
Jation of the blood is generally included under
the nutritive functions, because one of the most
important purposes served by the motion of
this fluid through the various textures and
organs of the body is the supply of those new
ingredients which are necessary to carry on the
process of growth and the changes of nu-
trition. A very slight acquaintance with ani-
mal physiology teaches us, however, that the
function of circulation has another very im-
portant and immediate use, viz, the support
of that condition of the textures and organs
which is necessary to enable them to exercise
their vital properties. It was on account of
the 2 see necessity of a constant supply of
blood for the support of the animal powers,
that Galen placed circulation, along with re-
Spiration, among the vital functions.

In the following article it is intended to de-
- scribe more particularly the course of the
blood in the human body and the powers by
which it is moved, and also to state the general
facts ascertained regarding the function of cir-
culation in other animals.

For the sake of clearness it will be neces-
gary to divide the subject into several de

CIRCULATION.

Dea The first of these will compre-
end a description of the course of the blood
in man; the second of its course in animals.
In the third will be considered the phenomena

presented by the blood during its motion, the

properties of the organs in which it circulates,
and the powers by which it is propelled ; and
in the fourth will be mentioned the more im-
portant circumstances connected with the other
functions which modify the circulation. .

The term circulation applied by its cele-
brated discoverer, Harvey, to the motion of the
blood, is sufficiently expressive of the general fact
that this fluid, or the greater part of it at least,
in being carried through the body, moves ina
circular course, or, that in performing its jour-
ney through the body, the blood always re-
turns to the same place from which it set out.
The term is equally applicable to the func-
tion by which a supply of nutritious fluids is
kept up in the lowest animals, in which a pro-
gressive motion of a fiuid of the nature of
blood takes place, as well as in the highest ; for
in nearly the whole of them there is a central
part of the circulatory organs, which forms the
rallying point, as it were, of the rest,-from
which the blood begins its course and to which
it is brought back, in a longer or shorter period
of time, after having passed through the dif-
ferent organized parts.

—-— = ee

I. CounSE OF THE BLOOD IN MAN.

The organs of circulation consist of the heart,
arteries, veins, and capillary vessels. We refer the
reader to the articles on thesedifferentorgansfor
all details relative to their anatomical structure.

In man and warm-blooded animals there
are two passages through the interior of the
heart, through each of which a stream of blood
is propelled at the same time, so that the heart
is alternately receiving and giving out a certain
quantity of blood upon each side.

The two auricles serve as receiving cavities
for the blood which is constantly flowing into
the heart from the veins or those vessels which _
have the office of returning blood to the centre
of the circulation. By the contraction of the
muscular parietes of the auricles, the blood is
propelled from these cavities into the ventricles,
which, in their turn, contract with force and
thus propel their contents into the arteries, or
those vessels which serve to transmit blood ~
outwards from the centre of the circulatory
organs. The auricles and ventricles of the
opposite sides acting simultaneously, and the —
size of these cavities on the right and left sides
of the heart being nearly equal, the quantity
of blood which is made to pass through each
of them at one and the same time must also b
nearly equal. i 2

The cavities on the left side of the heart
adapted to propel the blood into those artet
which are subservient to the nutrition of
body, while those on the right side of the ]
send the blood to the lungs for the purp
of respiration. The construction of the f
and the connection of its parts with tl
ries and veins are such that the whole.

CIRCULATION.

blood which has served the purposes of nu-
_trition, and the other uses for which the blood
_is destined throughout the body, on being re-
_turned to the heart, is directed by the cavities
_ on the right side of that organ to the lungs, and
made to through them before returning
to the left side of the heart to repeat its course
‘through the nutritive vessels of the body.

..In all those animals in which there exists a
_ disposition of the heart and bloodvessels such
_as that described, the circulation is said to be
double, because the blood is moved in two
circles at once, and the respiration is said to
be complete, because the whole of that blood
which has passed through the nutritive vessels
of the bee is subjected to the respiratory

action of air in the lungs.

_ The blood returned from the lungs of a
‘bright red colour, or arterial blood, on being
_ expelled from the left ventricle (fig. 312, H)

Fig. 312.*

-
--"

aon?
=
-

Pc heleialaieaietataetett oe
..
2 een

Circulation in Man.

_* In all the figures relating to the circulation in
different animals the same leiters indicate corres-
ponding parts as follows :
H, the heart or the common ventricle; h, the
- common auricle ;
_ A, the aorta or trunk of the systemic arteries ;
__ @, its branches ; a™, the carotids.
' V, the great systemic veins or vena cava infe-
4 tior; v, its branches; v*, the vena cava
: superior; c, the capillary vessels ;
_P, the pulmonary artery; p, the pulmonary
vein ;
B, the branchial artery; b, the branchial vein;
' D, the ductus arteriosus; d, ductus venosus ;
- f, foramen ovale ;
~ U, umbilical arteries ; u, umbilical vein ;

mn 4 4

639

by the muscular contraction of that cavity,
passes into the aorta or great artery of the
system (A), and is distributed in various pro-

ortions to all parts of the body by the

ranches of the aortic trunk (a) and their in-
finitely minute ramifications. The smallest
arteries lead, by an intermediate set of minute
tubes to which the name of capillary vessels is
given, into the systemic veins (v), all of which
(the veins of the intestinal canal excepted) join-
ing gradually together into larger and fewer
branches, form at last the great trunks of the
superior and inferior vene cave (V, v*), which
carry back to the centre of the circulation the
whole of the blood that had passed from the
left ventricle into the aorta.

In passing from the arteries to the veins
through the capillary vessels, the properties of
the arterial blood are changed; its colour is
altered from bright scarlet to dark purple,
it expends some of its substance in the nou-”
rishment of the textures, and a considerable
quantity of its thinner part transudes through
the small vessels, constituting the lymph that
is taken up by the absorbent vessels. The
venous or dark blood, as it approaches the
heart upon its return, has its composition fur-
ther changed by its admixture with the chyle
or imperfectly formed blood, which is the pro-
duct of digestion, and which is poured along
with the lymph from the thoracic duct into
the great veins of the head and superior ex-.
tremities.

By the changes thus produced in its com-
position, &c., the venous blood which returns
to the heart is rendered unfit for nutrition,
until it has been acted upon by the atmos-
pheric air in the lungs, which restores to it its
bright red colour and arterial composition and
properties.

The great systemic veins are therefore con-
nected with the right side of the heart (H’),
and the stream of venous blood brought by
them to the right auricle (h’), next issues from
the heart by the pulmonary artery (P), into
which it is propelled by the contraction of the
right ventricle ( H’) as it passes through that
cavity. The minute branches of the pulmo-
nary arteries and veins ( P, p), and the capil-
lary vessels by which they communicate with
one another, are wholly distributed on the
membrane lining the air-cells of the lungs.
In passing through these vessels then, the
venous blood is exposed to the action of the at-
mospheric air contained in the pulmonary cells ;
and, after having acquired arterial properties,
is returned to the centre of the circulation by

I, arteries of the intestine or alimentary canal ;
i, the ceeliac artery ;

L, vena porte; 1, hepatic vein, /*, hepatic

artery ;

K, advehent renal veins; hk, renal veins; *,

renal artery.

In those instances in which the parts are double,
those on the right sid2 are distinguished by the
accentuation of the letters indicating them, thus
P’ right pulmonary artery, P le!t ditto.

We beg to remind the reader that most of these
figures are merely plans, and that strict anatomical
accuracy is not to be looked for in them.

640

the pulmonary veins (p). The left auricle (A)
receives the newly arterialized blood from the
pulmonary veins, and transmits it to the left
ventricle (H), from which it is ready to start
again, when the ventricle contracts, on the
same course as has just been described.

In this double circulation, the path which
the blood traverses in passing from the left to
the right side of the heart through the aortic
arteries and the corresponding veins, has been
called the greater or systemic Circulation: and
the route of the blood from the right to the left
side of the heart through the pulmonary arte-
ries and veins has been termed the lesser or
pulmonic circulation. The names of pulmonic
and systemic, indicating the parts of the body
in which each of these circulations respectively
occurs, are on the whole preferable to the cor-
responding terms of lesser and greater.

There is still one part of the course of the
blood to be mentioned, viz. that of the venous
blood of the principal abdominal viscera
through the liver, or what bas been termed the
system of the vena porte.

The blood supplied by the eceliac and me-
senteric arteries (I, 7) to the abdominal viscera
is not returned directly to the heart by their
corresponding veins, as occurs in other parts
of the body. The veins of the stomach and
intestinal canal, of the spleen, pancreas, me-
sentery, omenta, and gall-bladder, unite to-
gether below the liver into one large vessel
(L), the trunk of the vena porte, which
branches out again and distributes to the liver
by its ramifications the whole of the venous
blood coming from the above-mentioned organs.
The blood of the vena porte, being joined in
the minute branches by that of the hepatic
artery (/*), passes into the smallest ramifica-
tions of the hepatic veins, by the principal
trunks of which (/), the venous and arterial
blood circulated through the liver is carried to
the inferior vena cava, and thus reaches at last
the right side of the heart.

Proofs of the circulation —After this brief
outline of the course which the blood takes
through the circulatory organs in man and
warm-blooded animals, itmay be proper to
introduce an enumeration of those circum-
stances which are generally adduced as af-
fording the most satisfactory “ proofs of the
circulation” or evidence that the blood pursues
the paths above detailed.

As proofs of the circulation, besides those
derived from the connection of the different
orders of great vessels with the cavities of the
heart to which they are respectively attached,
may be mentioned—

ist. The structure and disposition of the
auriculo-ventricular valves of the heart, and
semilunar valves of the aorta and pulmonary
artery, which admit of the passage of blood
from the auricles to the ventricles, and from
the latter cavities to the great arteries, but not
in a revérse direction.

2nd. The mechanism of the valves of the
systemic veins which allow of the motion of
fluid only in the direction towards the heart. _

8rd. The fact that when a ligature is applied

CIRCULATION.

to ah artéry, or any othet impe iment opposed _
to the free passage of siooe theeugh t, the
véssél becomes dilated on the side hext the
heart, while ots aap of a ligature to the
trunk of a vein is followed by 4 turgeséetice of
the vessel beyond the place where the obstrue-
tion occurs. a

4th. That onopening orieof the larger arteries,
blood issués in a jet from the énd next to the
heart at the time of évety contraction of that
organ, and that in general no blood flows from
the orifice of the remote part of the artery:
and that on opening a vein the converse is ob-
served, the blood issuing freely in a continued
stream from the remote part, but none proceed-
ing from the part of the vein adjoining the
heart.

5th. That the passage of thé blood from the
arteries to the veins in the small or éapillary
vessels has been observed by means of thé
microscope in transparent parts of animals,
and, though it has not been seen in man, we are
entitled from the general analogy in the struc-
ture of the organs of circulation to infer that
the same passage occurs in the human body.

6th. That, by mechanical arrangements,
fluids may easily be made to pass in the dead
body through the whole course of the double
circulation, but not in a direction different
from that which the blood has been stated to
pursue.

7th. That by the operation of transfusion,
the blood of one animal may be made to ciren-
late through the heart and vessels of another,
by connecting together the bloodvessels (whe-
ther arteries or veins) of the two animals, in
such a manner that the course in which the
blood is directed by the action of the heart of q
the animal from which the blood is derived is
that of the natural circulation in the animal into

PS.

which it is introduced.

8th. The phenomena presented by the circu-
lation of the blood in various diseased condi- :
tions of the heart and bloodvessels may be ad- i

duced as affording additional illustration of the
natural course of the blood, by pointing out the
effect of morbid obstructions and other varieties
in different parts of the circulatory organs.

Course of the blood in the fetus before birth.
—The double circulation just described is the
course performed by the blood from the time
of birth during the whole of life.

The circulation of the blood, however, begins
at a very early period of feetal life; but the
difference in the mode in which respiration is
effected in the child so long as it is contained
in the uterus, induces a modification in the —
course of the blood to which we shall now
advert.

There being no inhalation of air into the
lungs of the foetus, the blood is sent only in
small quantity to these organs, and does not
undergo in them any change of properties.
considerable portion of the blood of the feet
passes out of its body through the umbilieal
cord (fig. 313, U, u) into the placenta of the
uterus. ‘The minutely divided feetal vessels:
bathed by the blood of the mother containec
the placental sinuses, and, though no ¢

CIRCULATION.

Feetal circulation seen from behind.

continuity of tube exists between the maternal
and feetal vessels, the blood of the child seems
to undergo a respiratory alteration, or a certain
degree of arterialization, in being brought into
near proximity with the maternal blood.

The blood of the foetus, after passing through
the minute ramifications of the umbilical arte-
ries ( U’, U) in the placenta, returns by the
umbilical vein (w) into its body.

The umbilical vein carries part of its blood
directly by the ductus venosus (d) to the vena
cava inferior, and part is distributed by the
branches of the vena porte (L), with which
the umbilical vein unites, through the sub-
stance of the liver, and is then conveyed by
means of the hepatic veins (/) into the general
current of the returning blood.

The right auricle of the heart (h’), therefore,
receives not only the blood which has circu-
lated through the body of the fetus, but also
that which has passed through the placenta,
consequently a mixture of venous and arterial
blood ;—the blood in the superior vena cava
(v*) being entirely venous, that in the inferior
vena cava ( V_) being mixed. The blood which
is brought to the right auricle is in much
greater quantity in the fcetus before birth than
in the child which has breathed air; a part of
this blood passes from the right into the left
auricle (A) by the foramen ovale (f') in the sep-
tuth auricularum, and it would appear that it is
chiefly the blood from the inferior vena cava
which takes that course.

The rest of the blood entering the right
furiclé takes the same route as in the adult,
Viz. into the right ventricle (H’), and thence
into the pulmonary artery, but, as very little
blood is sent to the collapsed lungs, a passage

641

of communication is established in the foetus
from the pulmonary artery into the descending
aorta through the ductus arteriosus ( D ), and
thus the greater mass of the blood, which in
the adult would have proceeded to the lungs, is
in the foetus immediately transmitted to the
aorta ( A).

From the disposition of the Eustachian valve,
it is believed that nearly the whole of the blood
of the inferior vena cava passes from the right
to the left auricle through the foramen ovale,
while the blood brought from the head and
superior extremities (parts which are compara-
tively large in the foetal condition) passes
through the right side of the heart. The as-
cending aorta, rising from the left ventricle,
delivers almost all the blood expelled by the
contraction of that cavity into the carotid and
subclavian arteries, while the ductus arteriosus
passing between the trunk of the pulmonary
artery and the descending aorta directs the
blood which passes through the right ventricle
to the lower regions of the body. In this
manner the upper regions of the body are su
ee with the most arterialized part of the

lood from the left side of the heart and aorta,
while the purely venous blood is propelled
from the right ventricle through the pulmonary
artery and ductus arteriosus into the descends
ing aorta, and consequently into the lower part
of the body, and by the umbilical vessels to the
placenta.

The foramen ovale in the septum of the au-
ricles, the ductus arteriosus passing from the
pulmonary artery to the aorta, the ductus ve-
nosus leading from the umbilical vein to the
vena cava inferior, and the umbilical vein and
arteries are the structural peculiarities of the
fetal circulating organs. These passages are all
closed up, and the umbilical vessels obliterated
at the navel after aerial or pulmonic respiration
is established at birth.*

II. Coursk CF THE BLOOD IN VARIOUS
ANIMALS,

We now leave for the present the history of
the circulation in man, in order to give a brief
sketch of the varieties of this function in other
animals, the study of which is calculated to
throw considerable light upon some of the pro-
cesses of the human economy, and to illustrate
the anatomical and physiological relations of
the circulatory and respiratory organs.

It has been shewn that a regular and pro-
gressive circulation of the nutritive fluids occurs
in those animals only in which the aeration of
the blood is performed by a separate and dis-

* Sabatier, Mém. de |’Acad. An 8. Kilian,
Kreislauf im Kinde, &c. Karlshruhe, 1826. Bar-
dach’s Physiologie, &c. vol. ii. Jeffray, Pecu-
liarities of the Foetal Circulation. Glasgow, 1834.

t+ In the following view of the comparative phy-
siology of the circulation, besides the different
works referred to under the separate heads, we have
been guided chiefly by the following, viz. the works
of Cuvier, Home, Meckel, Blumenbach, Trevira-
nus, Carus, and R. Wagner; Roget’s Bridgewater
Treatise, and the excellent chapter upon this sub-
ject by J. Miiller in Burdach’s Physiologie, vol. iv.
and in his Handbuch der Physiologie, vol. i.

642

‘tinct respiratory apparatus; and that, amid the
. immense varieties of form which the circulatory
“organs present in different animals, the course
» of the blood bears a more close relation in all
‘to the form of their respiratory apparatus than
‘to any other part of their organization. This
general law of the relation between circulation
and respiration, satisfactorily established by the
extended researches of modern comparative
anatomists, receives farther confirmation from
_Many facts connected with the performance of
‘these functions in the adult human body, and
is illustrated in a peculiar manner by the re-
markable changes which take place in the cir-
culatory and respiratory organs of the child
_ before and after birth.

In treating of the varieties in the course of
‘the blood in different animals, we are at once
freed from any embarrassment regarding the
order proper to be pursued, by the circumstance
that the form. of the circulatory organs consti-
‘tutes one of the principal bases upon which the
-modern classification of animals is founded ;

so that,. in following the zoological arrange-
ment, we take the order best adapted for our
present purpose. As our object in giving this
sketch is principally to illustrate the structure
and functions of the human organs of circula-
tion, we shall begin with the consideration of
. the course of the blood in those animals which
most nearly resemble man; and trace the varie-
ties in this function, as far as our knowledge
permits, through the descending series of the
. animal chain.

1. Course of the blood in warm-blooded
animals.—In Mammalia and Birds, the form
of the organs of circulation and the course of
the blood are essentially the same as in Man,
for in all of these animals the heart contains
four distinct cavities,—two auricles and two
ventricles, and there is consequently a double
circulation and a complete respiration.

Some considerable varieties in the form of
the circulatory organs, which seem to have a
relation to peculiarities in habits or mode of
life, occur in certain mammiferous animals,
such as the Cetacea, Amphibious Carnivora,
the Sloths, Hybernating Animals, &c.; but we

‘shall not at present enter upon the considera-
tion of these varieties, because they do not
amount to any deviation from the type or
general plan of construction of the human
organs of circulation, and consequently are not
accompanied by any material difference in the
course of the blood, but seem rather to have
the effect merely of modifying the quantity of
blood sent to particular organs, or of influen-
cing its velocity and force.*

In the organs of circulation of the various
tribes of Birds, we observe the same remarka-
ble uniformity of structure which pervades the
rest of their internal organization.

It may be remarked that, as in Birds a cer-

~ tain respiratory action takes place in the large
air-cells distributed over the trunk of the body,
and as the pulmonary vessels seem in most
birds. not to extend to these cells, but to be

Pi gt

Boe 67,

CIRCULATION.

_ and Surg. Journ, vol. xix. p.

confined to the thoracic lungs, the blood con-
tained in the small branches of the systemic
arteries and veins, ramifying upon the lining |
membrane of the air-cells, must be made to
undergo some respiratory alteration of its com-
position; but we have not as yet obtained the
means of judging accurately of the extent to
which such a respiratory change may be effect-
ed in the vessels of the systemic circulation,
nor how far the minute branches of the pulmo-
nary vessels may in some instances be pro-
longed from the lungs into the air-cells.*

Very frequent anastomoses take place among
the veins of Birds. We may here mention one
of these which induces an important modifica-
tion in the portal circulation. By means of a
communicating branch which passes from the
united caudal, hemorrhoidal, and iliac veins to
the vena porte, the blood of the viscera of the
abdomen and of the posterior part of the body
may flow indifferently either into the vena cava
inferior or the vena porte, a disposition which
may have for its object to prevent congestion of
blood in the parts from which these veins pro-
ceed.t

|

A still more remarkable modification of the
venous circulation in Birds was supposed to ;
exist by Professor Jacobson of Copenhagen, |
consisting in the distribution of branches of the

vena cava inferior to the interior of the kidneys
and their subdivision in these organs, in the
same manner as the vena porte subdivides in
the liver. Such veins transmitting venous
blood to the kidneys, in the manner of a vena
porte, have been ascertained by Professor
Jacobson,{ and are admitted by others making
subsequent researches, to exist in Reptiles and
Fishes ; but Nicolai§ has shewn that the lower
veins, described by Jacobson in Birds as vene
advehentes of the kidney, do not differ from the
other branches of the vena cava, and serve to
carry away from these organs, like the superior
renal veins of Birds and the renal veins of
Quadrupeds, the venous blood derived from
the arteries.
Course of the blood in cold-blooded vertebra- 5
ted animals.—Of cold-blooded vertebrated ani-
mals, some, as the adult Batrachia, Chelonia,
Ophidia, and Sauria, breathe air by means of ‘9
lungs, while the rest, as the young Batrachia,
the Protean, and Siren-like Reptiles and Fishes,
are constant inhabitants of water, and breathe
the air contained in that medium by means of
gills or branchie. Of the aquatic cold-blooded
animals, Fishes breathe by gills only, while
the aquatic Reptiles or Amphibia are furnished
with lungs as well as gills during the greater
part of their aquatic life. ‘

>.%

* See the article Aves, p. 330.

+ It is a remarkable fact that there have been
found, between the hemorrhoidal veins in Man and
some branches of the vena porte, anastomoses by
small branches, which correspond in some respects —
with the disposition of the veins referred to above.
These anastomoses were known to Haller, and are —
lately described by Retzius. See his Researches in —

§ Isis, 1826, p. 414.

CIRCULATION.

' Reptiles—The structure and functions of
‘the circulatory organs in Reptiles form a sub-
ject of great interest on account of the nume-
rous varieties which they exhibit in different
orders and genera, for in this respect the class
of Reptiles may be said to present to us an
anatomical analysis of the circulatory and re-
- piratory organs, and to constitute a gradually
simplifying series of forms, the observation of

~ which enables us to trace in the most clear and -

interesting manner an analogy and correspon-
‘dence between the forms of these organs in

warm-blooded animals and in fishes, which, -

but for the study of their structure in reptiles,
must very probably ever have remained hidden

643

blood from. the’ system and the arterial blood
from the lungs. are received into. separate auri-

- cular compartments of the heart, and are sub-

sequently: mingled together ‘in the common

‘ventricular cavity. - In the Heart of the Croco-

dile of the Nile, Cuvier* has described three
compartments, one of which corresponds to the

deft, the other: two to the right ventricle,: the

septum between the right and left: sides. being
incomplete. The heart of the Crocodilus Lu-
cius is described by Hentz, Meckel,+ and
others as consisting of two ventricles, between
which the septum is quite complete,: so as to
permit of no direct passage of fluid from one
side to the other, possessing therefore in this

‘ from our view.
~ In Fishes the heart consists of one auricle
* and one ventricle, and a single current of blood
only passes through it. The structure of the
heart is very similar in some of the Batrachia
breathing by gills, but among other reptiles,

respect, the same structure as the heart of warm-
blooded animals. In those of the above-men-
tioned reptiles in which the septum is so nearly
complete as to divide the ventricle into two
separate compartments. communicating: by a
small orifice, the arterial and venous blood are

we find a gradual transition im the form and
structure of the heart from that just mentioned
as peculiar to animals with aquatic respiration,
to the double heart possessed by warm-blooded
and air-breathing animals.

Among the Reptiles provided with lungs and
- breathing air, some, as the Sauria, Ophidia, and
Chelonia, have the ventricular part of the heart
‘partially divided into two cavities (fig. 314,

Fig. 314.

Heart of Lacerta ocellata.

H, H') which correspond in structure, relative
situation, and connections to the right and left
ventricles of the heart of warm-blooded ver-
tebrata; the anterior or right compartment
if H’) giving off chiefly the pulmonary ( P_), the
left or posterior ( H ), the systemic arteries (A )/.
In the others, viz. the Batrachia and Protean
reptiles, the ventricle forms a single cavity
(figs. 317 and 318, H), and gives origin to
one large artery only (4), so that the pulmo-
nary and systemic arteries derive their blood
from the same trunk. In all of these, how-
* ever, the auricle is double,* so that the venous

’™ The auricle of the Batrachia was generally de-
scribed as single until the discovery of the left or
hyped auricle in the Frog and Toad by Dr.
John Davy. Mr. Owen has shewn this to be
the case also in the Newt and Protean Reptiles ;

believed to be kept separate from one: another
by a valvular apparatus. Among the rest of the
Saurian, Ophidian, and Chelonian Reptiles, in

Fig. 315.

Heart of Common Tortoise.

all of which the septum of the ventricular part
is less complete than in the Crocodile, there is
considerable variety in the extent to which the
division of the cavity is effected by the septum.
In a few of them the septum projects so little
into the ventricular cavity that it cannot be
supposed to divide to any extent, or to prevent
the complete mixture of the two kinds of blood
propelled from the opposite auricles.

In the Crocodile, and in those Reptiles in
which the ventricular septum is nearly com-
plete, the circulation, so far as regards the
heart at least, may be considered as almost
double, or the same as in warm-blooded ani-

Zool. Trans, 1834, p. 213. See also Martin St.
Ange’s Plate of the Circulation, and M. Weber,
Beitr. zur Anat. und Physiol. Bonn, 1832. ,° ~
* Legons, vol. iv. p. 221. .
+ Vergleich. Anatomie, vol. v. p. 231.

644

mals, that is to say, the arterial blood returning
from the lungs to the left auricle (fig. 314, A)
is directed entirely into the arteries of the
system (A) from the left com ent of the
ventricle ( Hf), and the venous blood brought
back to the right auricle (h') by the vene
cave (V wv) is directed wholly into the pul-
monary vessels al ) by the night ventricular
compartment (H’). _

Lacerta ocellata.

In all Reptiles, however, the descending aorta
is formed by the union of two branches, the
right and Jeftaortic arches (figs. 314, 315, 316,
and 317, A’, A); the right corresponds with the
systemic aorta of birds, and rises from the
left ventricular compartment, the left arch joins
the right on the back, and leads generally
from the right ventricular cavity into the
descending aorta. The arteries of the head
and upper extremities (fig. 314, a*), arising
from the right aorta (A’), which corres-
ponds with the aorta of birds, and is eon-

CIRCULATION.

nected with the left ventricular compartment,
are supplied with highly arterialized blood
proceeding directly from the lungs. The left
arch of the aorta (A), being connected on
the other hand with the rigbt ventricular com-
partment (H’), obtains, like the pulmonar
artery, venous blood from the right auricle; com
consequently the common trunk of the aorta,
formed by the union of the right and left aortic
arches, must carry to the posterior parts of the
body a mixture of arterial and venous blood.*
It may be remarked, however, that in the Turtle
and some Lizards the left aortic arch does not
ion the right upon the back until after it (the
elt) has given off the great celiac or rather
visceral artery, which supplies the whole of the
alimentary canal and digestive organs with ve-
nous blood (jig. 315, I). The left aorta is thus
much diminished in size before it sends its com-
paratively small communicating branch to the
right.¢ From this disposition of the parts, it ig
obvious that in these animals the abdominal
viscera must receive the greater part of the
venous blood brought from the right side of the
heart by the left aortic arch, while the right
aortic arch which gives the carotid, brachial, ver-
tebral, intercostal, and other arteries must carry
to the parts it supplies in the first part of its
course nearly pure arterial blood, and, after
it is joined by the left, blood which contains
a small proportion only of the dark or venous
kind. In the Turtle, some Lizards and Ser-
ents again, the arterial and venous blood must
e mixed in the ventricular cavity though par-
tially divided ; the two streams of blood pro-
pelled into the aortic and pulmonary vessels
must therefore be nearly of the same kind, and
thus a part only of the blood which is sent to
the lungs is made to undergo a respiratory
change. In some of the Chelonia, the exis-
tence of ductus arteriosi, leading from the pul-
monary artery on each side into the arch of the
aorta, insures a still more complete mixture of
the arterial and venous blood.j
In most of the adult Batrachia the ventricle
(fig. 317, H_), being single and giving rise to
one arterial trunk only (4), the pulmonary
arteries (P’, P) derive tneir blood from the
great systemic aortic trunk of which they are
branches; one coming off from each of the
aortic arches which unite to form the descend-
ing aorta. The venous blood returning from
the system (V v*) to the right auricle, is mixed
in the common cayity of the ventricle with the
arterial blood returning to the left auricle by
the pulmonary veins (p), and this mixed blood
being propelled into the aortic bulb is distri-
buted in part to the system and in part to the
lungs. In these animals then, only a small]
quantity of a mixed blood is. exposed to the
action of the air in the lungs, which, from the —
simplicity of their structure, offer only a con-

* In the Crocodile, the left branch coming from
the right ventricle is small and very short. a

+ See Bojanus’ beautiful Anat. Monography of —
the Tortoise. an

¢ In this respect, as well as in the mode Po ‘

origin of the left aortic arch, the Tortoise and Tur-
tle differ from one another. Tr

| CIRCULATION.

fined surface for the distribution of the pulmo-
nary capillary vessels.

In the aquatic Reptiles having gills, ‘such as
the larve of the Frogs and Salamanders in their
transitory conditions, and the Protean animals,

Fig. 318.

Proteus Mexicanus (Axolotl).

645

which are very similar to them, but do not un-
dergo, so far as is known, any further metamor-
phoses, the branchial organs are formed by an
extension or minute subdivision of branches of
the aortic trunk, supported upon the arches of
the hyoid bones. In all of these Reptiles, the
ventricle consists of a single cavity (fig. 318,
H), which propels its blood into the bulb or
commencement of the aortic trunk (A). The
aortic trunk divides into two branches, each of
which subdivides again into three or four ves-
sels upon each side of the neck. These vessels
( B), passing round the gullet or upper part of
the alimentary canal in the form of lateral
arches, unite again together behind, to form the
descending aorta. The branchial apparatus of
the animals now under consideration is formed
entirely upon these lateral arches of the aortic
trunk. In the larva of the Salamanders, in
the Proteus, Axolotl, Menobranchus, and
Siren,* the small branches of each gill are
formed by the minute subdivision of a loop of
vessel prolonged from the outer part of three of
the arches on each side into leafed processes of
the cuticular system attached to the hyoid ar-
ches ( B, 6).

The larva of the Frog has, in the earliest
stage of its existence, gills of the same kind as
those just described; but in its more advanced
‘condition these ‘external gills disappear, and
the larva of ‘the frog breathes by internal gills
more resembling those of fishes than the ex-
ternal branchize of the Newt or Proteus. The
gills of the tadpole of the Frog are covered
by the skin, and consist of a great number of
‘small leaflets, receiving the minutely ‘subdi-
vided loops of vessel given off for some way
along each of the four vascular arches as they
_ round the neck along the cartilaginous

oops of the hyoid bone. The vascular-arches
are double in that part of their course where
they are connected with the gill, ‘the blood
being transmitted from one branch to the other
in passing through the leaflets of the gill.

In the larve of the Batrachia, from a very early
period of their existence, as well as in the Pro-
tean Reptiles, there are lungs which seem to
be used as adjuvant respiratory organs, for they
are generally filled by the animal with air from
time to time. These lungs, more or less per-
fectly developed in different kinds of Protean
Reptiles, and at different stages of the existence
of the Batrachian larve, all receive a pulmo-
nary vessel from the vascular arch of the aorta
which is nearest the heart, whether this arch is
‘connected with a branchial apparatus or not.

In‘all'these animals the anatomical relations
and the mode of development of the blood-
vessels of the gills proves distinctly their re-
‘turning vessels to be, as much as those which
-conduct the blood into them, branches of the
‘arterial system; but the lungs on the other
hand, however rudimentary, are almost always
furnished with proper ‘pulmonary veins which
Yead to the auricle of the heart.

The following is the course which the blood
takes in this interesting class of animals. The

* We omit the consideration of the Amphiuma,
Menopoma, and Cecilia.

646.

heart (, H) receives the whole venous blood
of the body by the right auricle, and a small
quantity of arterial blood from the lungs by

e left. These two kinds of blood, mixed
together in the common ventricle, proceed
from thence into the aortic bulb and its

branches (.A, B, }). In the larva of the Sala-.

mander and Protean Reptiles, a part of the
blood is sent by pulmonary vessels to the
lungs, from which it is returned by the pul-
monary veins to the heart; a part passes di-
rectly round the arches, and gains the descend-
ing aorta; the greatest quantity passes out into
the gills, and after being arterialized returns to
be mixed with that in the aorta, so that a
mixed blood must permeate all the vessels of
the systemic circulation. In the Siren, accord-
ing to Cuvier and Owen, the whole blood goes
at once to the gills, from the want of any com-
municating twigs across the root of these
organs. It is interesting to remark that the
arteries of the head and upper extremities (a)
are not given off by the aortic arches until
after they are joined by the returning branchial
vessels, a disposition which is in some respect
similar to what we find in higher Reptiles, and
which seems to have for its object the supply
of a more pure arterial blood to the cerebral
organ.

In the larva of the Frog, the course of the.

blood is very similar. to that of Fishes. The
whole of the venous blood propelled through
the heart is sent into the gills, and is made to
pass through them before reaching any other
part. From the posterior parts of the first
arches are given off the vessels of the head, the
second form the right and left roots of the de-
scending aorta, and the fourth are continued
upon the lungs in the form of a pulmonary
artery. There is however also in the larva of
the Frog a short anastomosis between the out-
going and returning artery of each of the gills,
which allows of a direct passage of some blood
round the arches of the aorta.

In the Protean Reptiles and larva of the
Batrachia a greater quantity of blood is sent to
the respiratory organ than occurs in the adult
Frog or Salamander.

Portal circulation in Reptiles——In the clas
of Reptiles there are two lesser venous circula-
tions besides those already described; the one,
similar to the portal circulation of warm-blooded
animals, belongs to the liver; the other, which
does not appear to occur either in Birds or
Mammalia, belongs to the kidneys. According
to Jacobson, who was the first to point out the
existence of veins carrying blood to the kidneys
in the Amphibia, and the later researches of
Nicolai.and others, there are two principal ves-
sels which carry back blood from the posterior
parts of the body, viz. the anterior abdominal,
and the inferior renal veins. These two vessels
are formed by the union of the iliac, caudal,
posterior cutaneous, pelvic, visceral, abdominal,
and umbilical veins; and in most Reptiles, ex-
cepting the Ophidia, the renal and portal vessels
proceeding from the posterior parts of the body
arise together. In some Reptiles the whole of

‘the blood returning from the posterior parts of

CIRCULATION.

a
a)
2

the body is divided between the portal veins of
the liver, and the vene advehentes of the kidney ;
in others a part is also sent into the abdominal
vena cava. The inferior renal or advehent
veins of the kidneys (figs. 316, 317, and 318,
K) carry venous blood to these organs, and
distribute it minutely through their substance.
It is removed from thence and returned into
the great circulation by the revehent or superior
renal veins (k) which lead into the vena cava.*
The anterior abdominal vein (fig. 316, w) is the
same to which Bojanus has given the name of
umbilical in the Tortoise, in which class of ani-
mals it is of very large dimensions, and receives
not only the venous blood from the terior :
extremities and shell, but also some from the ;
anterior extremities. The persistence of those :
umbilical veins which proceed from the large q
urinary bladder in many of the adult reptiles is
a fact of some interest, because it points out a i
resemblance between the permanent distribu-
tion of the vessels in these reptiles and the
foetal condition which we find in the higher
animals, and likens the bladder of the scaly
Reptiles, as well as of the Batrachia in which
during fcetal life no allantoid membrane is ever
formed, rather to an allantoid receptacle than
to a proper urinary bladder.

Fishes.—In_ fishes there is no vestige of a
pulmonary organ, and the respiration is wholly
effected by means of the gills. The branchial
apparatus of fishes is internal or covered, like.
that of the larva of the frog; it is placed on.
the cervical part of the alimentary canal, and
is formed by the fine subdivisions of aortie.
arches (fig. 319, A, B, b), which are prolonged:
into the fringed or leafy processes of the hyoid
branchial arches. The respiratory organ is
thus placed in this class in the course of the
arterial circulation. The venous blood from
the body generally, and from the liver, enters
the single auricle (A) through the great sinus
(V), and is wholly propelled into the arterial
bulb by (A ) the single ventricular cavity ( H ).
No systemic arteries come from the aortic bulb,
but this vessel carries by the arches into. which
it divides (.B), the whole of the venous blood
into the gills. The number of these arches im
subdividing and ramifying in the gills varies c
in different fishes. In a few, as the Lophius, |
there are only three on each side. In most
osseous fishes there. are four. In the Skates
and Sharks there are five. In the Lampreys
there is the greatest number known, namely,
Six or seven. )

The blood, after having undergone arteria-_
lization in the gills, is not returned to the heart,
but proceeds directly through the branches of
the aorta (fig.319*, bb, A) to different organs.
The force of the heart acts therefore through the _
whole of the capillary system of the gills (bc), —
and continues to propel the arterialized blood —

* It must be remarked that Meckel, who appears
to have examined the distribution of the above mei
tioned vessels with great care, denies entirely
advehent function of the lower veins of the kidn
both in fishes and reptiles, considering all the veims
of the kidney as revehent. Vergleich. Anat. B.V.
S. 201 and 258. 6 ae as 't

CIRCULATION.

Fish.
through the branches of the aorta (A) in the

various parts of the systemic circulation. Dr.
Marshall Hall* and J. Miillert have observed a
dilated contractile part of the caudal vein in the
tail of the Eel, to which Dr. Hall has applied
the name of caudal heart, which may assist
in promoting the flow of blood in the caudal
branches of the vena cava.

The position and anatomical relation of the
heart of fishes with the bloodvessels as well
as other shew that it corresponds to
the whole heart of higher animals, and: that
the arterial vessel which receives the whole
of the fish’s blood from the ventricle may
strictly be considered as the commencement
of an aorta entirely destitute of any pul-
monary branches. Although there is no dis-
tinct right ventricle to propel the blood to
a pulmonary organ, and the whole of the
blood issuing from the heart is sent directly to
the gills, there is not on this account any suf-
ficient reason for considering, as some have
done, the heart of the fish as corresponding to

7 = Essa on the Circulation of the Blood, p. 170.
Lond. 1831.

+ Handbuch der Physiol. vol. i.

647.

the pulmonary or right ‘cavities of the heart in
warm-blooded animals, for we have seen that®
in some of the reptiles when they have gills, .
the blood is driven into these organs through.
the aorta or systemic trunk. The branchial’ -
arteries in fishes, as in reptiles, are therefore”
branches of the great aortic trunk, and the
returning vessels on the posterior side of the
arches, or branchial veins as they are called,
are as much of an arterial nature both in their’
structure and relations as the anterior vessels’
or branchial arteries are.. When these return--
ing vessels unite together on the back to form:
the descending aorta, it is not necessary there-»
fore to suppose them to undergo a change from
the venous to the arterial structure. So far
then as general structure and relative position’
are concerned, the heart of the fish corres=-
ponds to the whole heart of warm-blooded:
animals, and not to one or other set of its:
cavities. Nor does the contemplation of its:
function or uses in the circulation induce’ us >
to modify this view, for it is manifest that: the
heart of the fish, as it serves to propel the~
blood through the gills into the vessels of the:
system, and as the branchial vessels may be
considered as belonging to the aortic system,
acts at once as a branchial and a systemic
heart.*

We have abstained from entering at this
place into the detail of those remarkable
changes formerly alluded to, which the
circulatory and respiratory systems and the
systemic and branchial or pulmonary circu-
lations undergo during the development of the
young of animals, although these afford. the
most direct proofs of the justness of the view
now taken. Under the head of Ovum we
shall have a more fitting opportunity of ex-
plaining these fully. Suffice it for the present:
to say that the heart of the highest warm-
blooded animals passes, during the progress of
its development at different periods or stages,
through the same general outline of various
forms which that organ retains permanently in
the adults of fishes or different reptiles; and
that the aortic’ arches and a semblance of a
branchial apparatus connected with them is
not confined to those animals which necessarily
employ gills for a time as respiratory organs,
but are to be found also in the fcetus of the
scaly reptiles, birds, and mammalia in the
early stages of their existence. The ductus
arteriosus, double in birds and single in mam-

‘malia, is, we may remark, the last of those

transitory structures’ which remains in the
foetus. :

Portal circulation of fishes.—In fishes, as
in’ reptiles, both the liver and kidneys have
venous blood distributed to them by the sub-
division within’ these organs of veins (L.& K)
from the abdominal viscera and posterior parts
of the body. The vena porte of the liver
consists generally of veins from the stomach,
intestinal canal, spleen, pancreas, and somie-
times from the genital organs, swimming blad-

* Blainville, Sur la Degradation du Ceeur,..&¢s
Bull, de la Soc. Philomathique, 1818-9, ps 148.3

C48

der, and tail. There is, however, considerable
variety in regard to the distribution of the
posterior abdominal veins in fishes; and com-
— anatomists do not appear as yet to
ve connected these varieties with any general
view of their uses. In the Gadus the venous
blood from the tail and middle of the ab-
domen goes to the kidneys only by venz ad-
vehentes. In the Silurus the blood of the
posterior parts of the body is carried to both
the kidneys and liver; and in the carp, pike,
and perch, to the kidneys, liver, and vena
cava at once. The blood from the testicle,
ovary, swimming bladder, and kidneys, most
frequently goes to the venacava.*

Course of the blood in Invertebrate Animals.
—In investigating the course of the blood in
animals destitute of a vertebral column and
cerebro-spinal nervous system, we are no longer
guided by any such analogies of form, posi-
tion, and use, as those just attempted to be
traced in the circulatory organs of the Ver-
¢ebrata ; for each class of Invertebrate animals,
as Mollusca, Articulata, and Zoophyta, and
even their subordinate orders, differ so widely
from one another in their organization, that
we are at a loss to discover any general plan
‘or type to which their circulatory organs may
be referred.

In all of the Invertebrate animals im which
there is a regular progressive motion of the
mutritive fluids, there exists also a central con-
tractile organ to which the name of heart is
applied, from its functional rather than struc-
dural analogy to the central propelling organ
of the circulation in Vertebrate animals; and
in many of them, the outgoing and returning
vessels in which the circulation is performed
amay be distinguished into arteries and veins,
‘by a difference of structure as well as of office.
krom the same kind of analogy, the name of
auricle is given to the weaker part of the heart
of Invertebrate animals, which serves to re-
ceive the returning blood from the veins, when
such a-cavity exists, and we call ventricle the
stronger and more muscular part which propels
the blood into the arteries. The general form
of these parts, however, and their position
relatively to the other systems, render it ex-
tremely difficult, if not altogether impossible,
to trace any strict anatomical correspondence
between the heart and bloodvessels of Verte-
‘brate and Invertebrate animals. In the Inver-
tebrate.animals, the heart and principal artery
sare generally placed on the upper part of the
‘body, above the alimentary canal and largest

rtions of the nervous system; while in all

ertebrate animals the order is reversed, the
‘brain and spinal marrow being above, the
heart below ‘the alimentary canal.

Inthe Eavertebrata, asin thehigher animals,
the respiratory ‘change of the ‘blood is:the most
amportant function to which its course or cir-
culation ‘bears .a constant relation. In ‘the
Vertebrata the ‘blood ‘flows from the heart to

* See the papers of Jacobson and Nicolai al-
ready referred to, and the extended Researches of
Rathke, Meckel’s Archiv, 1826, and Annal. des
Sciences Nat. tom. ix.

CIRCULATION.

the respiratory organ, while in the Invertebrata
the blood very generally arrives at the heart
after having passed through the respiratory
organ, and is propelled from the heart into the
systemic circulation: the vessels, therefore, in
which respiration is effected in the lower ani-
mals may be considered as belonging in ge-
neral to the venous circulation only, while in
the higher classes of animals, arteries alone,
or arteries and veins together, conduct the
blood through the respiratory organ. Another
remarkable difference between the circulation |
of the nutritive fluids in Vertebrated animals
and that in the Invertebrate classes consists in
this, that in the first the digested food or chyle
and the lymph are taken up by a system of
vessels distinct from those circulating blood,
and are poured into the venous circulation.
at one or more determinate places; while in
the latter animals, the bloodvessels, so far at
least as we yet know, perform the office of
lacteal and lymphatic absorbent vessels as well
as of circulatory organs. In the Invertebrate
animals also, there is no vena porte, as in the
Vertebrata, and the liver is supplied with blood
only by a hepatic artery.

In investigating the structure of the circu-
latory organs in different classes of Inverte-
brate animals, we at once perceive that no
accurate correspondence can be traced between
the varieties of their forms and the places
assigned to the animals in a Zoological arrange-
ment; for we find among the Mollusca some
tribes having a highly developed and compli-
cated circulatory apparatus, and others with
heart and bloodvessels comparatively simply
organized. The same discrepancy occurs
among the Crustacea, Annelida, and Insects ;
and among the Entozoa and some other tribes
of Zoophytes, while some possess a simple
circulatory apparatus, in others we are not able
to discover any vestige of a vascular system.

There is a considerable number of the lower
animals in which no vascular system ‘has ‘yet
been discovered, and in which the nutritious
juices are supposed to pass from the alimentary
cavity by interstitial transudation through all the
parts of their bodies. The circulation has, how-
ever, been recently shewn to exist in animals
formerly believed to be without it, and the
farther progress of Comparative Anatomy may
diminish still more the number of animals
believed to be destitute of circulating organs:
in ‘the present state of our knowledge, it is
therefore as difficult to say with certainty in
what animals this function is deficient, as it is
‘to fix in which it is of the most simple or most
‘complicated kind.

Motlusca.—The ‘greater number of the Mol- —
lusca live in water and breathe by means of

gills, but many aquatic Mollusca, poe
a ‘branchial acnelina appear to have their
blood ‘aerated in other’parts of the body also. —
There is a strong muscular ‘heart in all-the ani-
mals belonging to this class, which when’single
is always systemic, (figs. 320, 321,and 322, H.)
In the Cephalopoda, besides the aortic or sys-
temic heart, which has only one cavity or
ventricle, each vessel (fig. 320, B)

CIRCULATION.

Ze} of,

crteahtre init :
Tn nbngheeeeeeatinice Ss

Wh Veg
mah Veale
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the gills has a dilated contractile portion (.B*),
which dilatations: may be considered as bran-
chial hearts, so that there are three separate
contractile portions of the circulatory system.
In the Gasteropoda and Pteropoda, there is
only one heart. This organ is strong and mus-
cular, provided with valves, and consisting of
an auricular and a ventricular cavity (figs. 321
and 322,4, H). In the Testaceous Acephala,
the heart is nearly of the same structure as in
loped. In most of them, as also in the Gas-
teropodous Mollusca, the rectum passes through
the ventricle. The auricle is occasionally
double. The Brachiopoda have two aortic
hearts, but of a very simple structure, not
being divided into auricular and ventricular
portions. The naked Acephala, such as the
_ Ascidie, have the simplest heart of all the
_ Mollusca, consisting of a thin membranous
ventricle apparently without valves.

_ In all these animals, the course of the blood
is generally considered to be the following:
_ Arterial blood only passes through the systemic
or aortic heart (or
_ double), and is carried to the system by the
_ branches of the systemic arteries (A, a). The
VOL. I.

the orders just mentioned, but less fully deve-

earts where this organ is:

649

altered blood, returning in the veins of the
system, is collected into one or more trunks
(V), and carried in the subdivided branches
of these (fig. 321, fig. 322, B) to the re-

Fig. 321.

hs. ;

(Kt Ai,

a itenee
att

Helix.

spiratory organ, which consists of branchial
plates or fringes in the greater number, but in
some of the Gasteropoda, as in the Garden-
Snail, of pulmonary sacs. In most cases, the
whole of the blood returning from the system
passes through the respiratory organ. In
others, especially in some Bivalves, the vena
cava or systemic veins send branches directly
to the auricle as well as to the gills.

In the compound Ascidie, Mr. Lister* has
recently discovered one of the most remarkable
modifications of the circulation with which we

* Philos. Trans. 1834, p. 378.
2uU

650

are acquainted. Mr. Lister finds that the dif-
ferent Ascidiz of a branched animal are not only
connected together by the polypiferous stem,
but have a common circulation. In each indi-
vidual there is a heart consisting of one cavity
only, and pulsating about thirty or forty times
ina minute. In the common stem, the mo-
tion of the globules of the blood indicates
distinctly two currents running in opposite
directions. One of the currents enters the
Ascidia by its peduncle and proceeds directly
to the heart ; the blood issuing from the heart
is propelled into the gills as well as the system
at once, and upon its return from thence the
returning current proceeds out of the animal
by its peduncle again into the common stem,
whence it goes to circulate through another of
the ascidiz attached to the stem. The direc-
tions of the currents appeared to be reversed
every two minutes or less. According to Mr.
Lister, when one of the ascidie is separated
from the common stem, its circulation goes on
in an independent manner; the blood return-
ing from the body being conducted into the
heart, but the alternation of the directions still
continues,—a circumstance which points out an
important difference between the compound
and the simple ascidiz, in which last the cir-
culating fluid is generally believed to pass from
the gills into the heart, and to hold continually
the same direction.

Articulata.—In this class of animals,
varied as the forms of the circulatory organs
appear, the position of their principal parts is
much more constant than in the Molluscous
animals. In some, as the Decapodous Crus-
tacea, there is a short and thick muscular heart
connected with the systemic arteries. In
others, the contractile part of the vascular
system is much more like a dilated artery than
a circumscribed heart, as occurs in some other
Crustacea, spiders, and insects; and in the
Annelida the greater part of the large vessels
seem to be endowed with a contractile power
by which they propel the blood.

Annelida.—Although the Annelida form the
highest division of the class Articulata in the
arrangement of Cuvier, their circulatory organs
may for the most part be regarded as more
simple than those of most of the others. ‘The
circulation is best known jn the Naides, the
Leech, Earthworm, and Sandworm. In all of
these, the blood, which is generally red, moves
gradually forwards in the vessels situated on
the upper surface of the animal, and backwards
in the vessels placed below or on the abdomi-
nal side. ‘There are also numerous cross vessels
which transmit the blood from one side to
another, or from above downwards, or from be-
low upwards, in each of the compartments or
joints of the animal. The upper vessels, being
generally the most contractile, are considered
as the arteries ; the lower vessels as veins.*

The organs of circulation appear to be sim-
plest in the Naides. In these animals, the
contractile part or heart is represented by an
artery above. This vessel turns round at the

* Sce the article Annelida, p. 169,

CIRCULATION.

head into the vein which is below. The a “sa
sends its blood partly into the gills, placed =
along the whole length of the bee from which
it again receives the returning blood, and by
numerous lateral branches, which may be re-
garded as the only capillary vessels, it sends
blood across the body of the animal into the
vein. The motion of the blood appears to be
partly progressive and partly oscillatory.
Lumbricus. —In the common earthworm,
there are two principal vessels, the one (fig.

323, a,) placed above and the other (v) below,
and extending the

whole length of
the body; these
two principal ves-
sels communicate
together by very
numerous small
cross branches (c), >
and, in the neigh-
bourhood of the
ovaries, by from
five to eight very
remarkable neck-
lace-shaped or
moniliform _ves-
sels (h, H). At
the place of junc-
tion of these mo-

_ te — = ° ~~ we, were hs

2
way

are also three other
longitudinal ves-
sels, much smaller
than the principal
or median ones,
which join with
the cross anas-
tomosing _ twigs.
The upper principal vessel pulsates in an un-
dulatory manner, the contraction taking place
first at the posterior part, and proceeding gra-
dually forwards. In these animals, however,
the course of the blood does not appear to be
very well known. It is believed to be from
behind forwards in the upper vessel and from
before backwards in the lower, but there must —
be also lateral motion. Both the upper and —
lower vessels are said to give off pulmonary —
branches.

Arenicola —In the sandworms also, besid
the principal upper and lower vessels, there at
two smaller ones, placed one on each side of t
abdominal nervous cord, and two others upon th
intestine; between these there is a very mim
net-work of smaller branches. The branc
arteries are derived from the upper longitudi
vessel, the branchial veins lead into the
The greater part of the blood poe
upper vessel into the gills by the brane

.
; niliform vessels |

i with the lower
cout longitudinal one,
— there are small di- f
= latations of that
= -c vessel, which are :
Suk Eo | believed to aid in
S11 = propelling the ;
a) § blood by their con- 7
sme tractions. There }

ree TT ec

nen UC
yl

CIRCULATION. 651

ries ; by the branchial veins it gains the lower
vessel. This vessel may be regarded as the
systemic artery, and sends the arterial blood,
by the numerous anastomosing branches, up-
wards across the intestine, and through the
other parts into the upper vessel. The upper
vessel communicates also with the lower ante-
riorly by the lateral dilatations named auricles,
which are supposed to furnish some blood to
the upper vessel. A part of the blood at the
anterior extremity of the lower vessel is said to
be propelled into the two subordinate vessels
aes along the sides of the nervous cord.
n this course which the blood is stated to
follow, it does not appear to be known whether
its motion is of a regular progressive kind or
only undulatory.
ech.—In the leech the principal and most
highly contractile longitudinal vessels are placed
one on each side (fig. 324, a, a), and there are
also two lesser longitu-
dinal vessels, one supe-
rior and the other inferior
(a*), all which commu-
nicate freely together by
small cross branches along
the whole body (c). It
isremarkablethat the lower
median vessel (a*) incloses
the ganglionic nervous
_ cord, so as to bathe it with
blood. Both pulmonary
arteries and veins are
branches of the lateral ves-
sels; a capillary network
between them distributing
the blood minutely over
the pulmonary sacs or
vesicles. The pulmonary
veins form veryremarkable
dilated and coiled por-
tions, which seem to be
endowed with a high de-
gree of contractility. Ac-
¢ cording to J. Miiller, for
a certain number of pul-
sations, the middle and the
lateral vessel of one side
contract together, and pro-
el the blood into the
teral vessel on the other
side, and then the order
is reversed, and the middle
vessel acts along with
the lateral vessel of the
other side, so that one lateral vessel is always
dilated while the median and opposite lateral
ones are contracted, and vice versa. According
to some there is thus only an alternate motion
of the blood from one side to the other, while
others believe that there is at the same time a
gradual progressive motion of the blood for-
wards in the upper vessel and backwards in
the lower one.*
The course of the blood in the principal

Fig. 324.

&

Hiretwinyw isl

Erpobdella or Leech.

* See a full account of most of the opinions of
observers on this subject, as well as original obser-
as by Rudolf Wagner, in the Isis for 1832,
p- *

parts of the circulatory organs is nearly the
same in the rest of the Articulata, viz. Crustacea,
Arachnida, and Insects, as in Annelida. In all
of them the central propelling organ, whether in
the form of a heart or consisting only of a dilated
arterial vessel, such as the dorsal vessel of .in-
sects, is situated on the upper surface of the
animal, above the alimentary canal, while the
returning vessels are situated on the lower sur-
face of the body, on each side of the nervous
ganglionic cord. The respiratory circulation,
when occurring in a distinct set of vessels,
forms a part of the venous system, and the
heart, which has no auricle, is systemic or
aortic.

Insects—All perfect Insects, whether inha-
bitants of air or water, breathe air alone. In
these animals there is not a separate and dis-
tinct respiratory organ in one part of the body
only, but the atmospheric air is carried by
minute elastic and tough tubes ramified to an
infinite degree of minuteness into every part of
their body.

The dorsal vessel of insects forms a long and
wide contractile artery, larger in general behind
than before, in which the contractions begin at
the posterior extremity, and proceed gradually
forwards with an undulatory motion. In the
greater number of perfect insects, we are not
acquainted with any other vessels or passages
in the body, through which the blood moves,
and this fluid seems in these insects to oscillate
backwards and forwards in the dorsal vessel
alone. ‘This state of the circulation in insects,
according to the ingenious views of Cuvier, is
related to the distribution of the respiratory
organ over the whole body, in consequence of
which the air is brought in contact with the
more perfect blood contained in the dorsal
vessel, and the nutritious fluids supposed to
pervade interstitially the rest of the body. The
recent discovery by Carus of a continuous cir-
culation of the blood through arteries and veins
in a few of the perfect insects, and more espe-
cially in some larve, must modify the above
views, which, ingenious as they must appear to
all, do not account so satisfactorily for the ab-
sence of a systemic as for the want of a pulmo-
nary circulation. The circulation of the blood
of Insects may be most easily seen in the
aquatic larve of Neuropterous Insects, as the
Agrion, Ephemera, Semblis, and Libellula,* in
which it was first discovered.

In these larve it may be described generally
as follows. The dorsal vessel (fig.325, H_) is
connected anteriorly and posteriorly by several
branches with the inferior or returning vessels
(v, v), which, running along the whole body,
receive the blood from the anterior extremity,
and carry it into the posterior extremity of the
dorsal vessel. The antenne and first joint of
the legs, as well as the fin-shaped caudal pro-
cesses, receive each a loop of vessel from the
abdominal current; and from the motion of the
globules in these transparent parts, the circula-
tion can be more easily seen in them than in

* We have ourselves seen the circulation in the
larye of two Neuropterous Insects.

Se UHe

652

Insects.

any other parts (fig. 325 **, a,v). A net-
work of vessels is also distributed over the
surface of the imperfectly formed wings. As
the metamorphosis from the larval to the
perfect state advances, and shortly after the
insect leaves the water to assume the aerial
condition, the circulation of the blood be-
comes gradually confined to a more and
more circumscribed space. The loops extend-
ing into the wings, limbs, caudal processes,
and antenne, become shorter; when the meta-
morphosis is complete, they become entirely
closed, and in general this change is followed
by the disappearance of the inferior lateral or
returning currents also. These remarkable
changes in the circulatory organs at once indi-
cate an interesting relation of their condition to
the changes in the mode of life of the insect,
In the aquatic state, the caudal and lateral
laminz, antenne, and wings may be considered
as serving the purposes of gills, for the blood
1s carried to them, and exposed upon their
surfaces to the action of the water. The larve
of the neuropterous insects generally feed
largely, but their life during the perfect condi-
tion, when the circulation has ceased, is of
short duration, and they either take very little
food, or live in absolute abstinence. It has
been also shewn that the dorsal vessel consists of
different compartments, between each of which
a valvular apparatus (fig. 325*, x) prevents the
passage of the blood in a retrograde direction.
There are lateral openings in the neighbourhood
of the valves, by which it would appear that

_

CIRCULATION. :

the blood is admitted into the dorsal vessel from
cross branches (fig. 325**, y) passing directly ~
from the lateral streams. It may be mentioned __
that the larger returning streams of blood, situ-
ated on the lower side of the body, are said by
Carus and Wagner, we cannot judge with what
reason, not to be inclosed within vascular pa-
rietes, but to run loose in the texture of the ©
insect. A complete circulation is not, how-
ever, confined to the larve of insects, having
been discovered by Carus and others in some
of the perfect insects. Carus saw it in the —
wings of the Semblis developed for flight. The
circulation has also been seen by Carus in the
larvee of Water-beetles, Hydrophilus, and Dy-
tiscus, and by Ehrenberg and Hemprich in the
Mantis, so that the circulation has now been
discovered in insects belonging to four orders,
viz. Coleoptera, Diptera, Orthoptera, and Neu-
roptera.

_ Crustacea.—In the Stomapoda, Isopoda, and |
Branchiopoda, or in the Squill, Oniscus, and
Monoculus or Daphnia, the circulation is ge-
nerally deseribed as being of the same simple ;
kind as that just stated to occur in the larva of 4
insects, with this exception, that the blood is
carried to gills for the purpose of undergoing
a respiratory change. In most of them the
venous blood which is sent to the gills comes |
directly from the systemic veins. From the
description given by Gruithuisen of the circu-
lation in the Daphnia,* it would appear, if his 1

|
‘

=

observations are correct, that the venous blood
is sent to the heart before going to the gills,—
a distribution very dissimilar from that which
exists in the rest of the articulated animals. In
this animal, Gruithuisen also describes an au-
ricle and ventricle in the heart.

The investigations of Messrs. Audouin and
Milne Edwards have pointed out very clearly
the structure of the circulatory organs and the ;
course of the blood in the larger Decapodous }
and some other Crustacea. The aortic heart 4
(fig. 326, H_), consisting of a single ventricuiar 7
cavity, and situated below the posterior margin
of the thoracic shield, gives off six systemic
arteries (A, a), which convey the arterial blood
to the various organs of the body and to the
liver (/*), The venous blood, returning thence
in the systemic veins (v, v), is collected on the
lower surface of the body into sinuses (V,V),
from which the branchial arteries (.B) take their
origin ; the branchial veins (6) return the blood
which has passed through the gills to the heart.

Arachnida.—In those of the Arachnida in
which the respiratory organ consists of tracher _
like that of insects, the circulation has been
supposed to be much the same as in these i
latter animals. The dorsal vessel, however, —
approaches to the form of a heart posteriorly
being there more dilated at one part than
the rest of its course, and considerable le
vessels are known to be given off from it”
either side. In others of the spiders, in whic
the respiratory organ consists of pulmonary ¢
vities admitting air, it is conjectured that
blood is distributed on the surface of the

ve

* Nova Acta Nat. Cur, xiv. p. 404. .

CIRCULATION. 653

Lobster.

within these sacs, as upon the gills or lungs of
other animals, but the exact course of the blood
does not appear as yet to have been satisfacto-
rily ascertained in these animals. Audouin*
believes it to be essentially the same as in the
Crustacea. The long-shaped dorsal vessel or
heart gives off arteries to both sides, and re-
ceives at one place branches from the gills.
The veins form only spaces or sinuses, and not
vessels on the abdominal side of the animal.
The blood propelled from the artery is passed
through the system, returning from which, it is
collected into the venous sinuses below, thence
it proceeds to the pulmonary organs, and after
passing through them, returns to the heart.

Zoophytes.— The general character of the
circulation in this class is exceedingly ob-
scure ; for while in some of the animals be-
longing to it, comparative anatomists have not
succeeded as yet in pointing out any distinct
vascular system; in others, they have been at a
loss to determine, among various vascular or-
gans, which of them forms the proper circula-
tory system corresponding with that of higher
animals.

Echinodermata.—Among the Zoophytes the

* See the article Arachnida, p. 206.

Echinodermata present the most fully deve-
loped vascular system with which we are ac-
quainted. According to the observations of
Tiedemann and Delle Chiaje, who have inves-
tigated the structure of these animals with great
success, there are two principal divisions of the
vascular system, described by the first of the
above-mentioned authors as distinct from one
ames by the other as communicating toge-
ther.

We do not feel inclined to consider, in ac-
cordance with the view of these authors, that
series of cavities which is employed in loco-
motion as a part of the nutritive circulatory
organs.

That part of the vasctlar system of these
animals again, which is situated in the neigh-
bourhood of the alimentary canal, very proba-
bly corresponds with the circulatory organs
which we bask been describing in other ani-
mals; since arteries and veins can be distin-
guished in it, and there is good reason to be-
lieve that a circulation of fluid takes place
through its vessels in all the kinds of Echino-
dermatous animals.

In the Holothuria, the principal artery or
heart is connected with a ring situated round
the commencement of the alimentary canal,
from which the systemic arteries are given off :
the systemic veins send branches to the gills,
and the returning vessels from these organs
transmit the circulating fluid through one large
trunk into the heart.

The intestinal vascular system of the Asterias
and Echinus is somewhat similar to that of the
Holothuria, consisting of annular vessels, from
which arteries and veins are given off, and con-
nected with a dilated contractile canal, consi-
dered as a heart.

Planaria:—Next to the Echinodermata in
respect of the degree of perfection of their cir-
culatory organs, may be mentioned the Plana-
riz, in which M. Duges* has pointed out a
very remarkable system of vessels which ap-
pear to constitute circulatory organs (fig. 327,
a,a). For some time previously to the disco-
very of these vessels, the sin-
gularly branched intestinal ca-
vity of the Planaria and some
Entozoa was believed to hold
the place of organs of circula-
tion, the same cavity in which
digestion occurs being believed
to carry by its ramifications the
nutritious fluids to different
parts of the body. But Duges
has shewn the existence in them
of asystem of vascular organs
resembling considerably those
of the Leech, to which animals
the Planaria bears, in other parts
of its organization also, astriking
analogy. The vascular system
of the Planaria consists of three
principal longitudinal trunks,
two lateral and one dorsal or median, which are
all united together by numerous minute anasto-

Planaria.

* Annal. des Sciences Natur. xv. p. 160.

654

mosing vessels. The larger parts of the longi-
tudinal vessels have been observed to contract
and dilate; but neither a regular progressive
circulation, nor a connection of the vascular
with any distinct respiratory system has as yet
been detected.

Entozoa.—In the Entozoa, organs of circu-
lation somewhat similar to those just mentioned
in the Planarie have been found by Bojanus
and Mehlis in the Distoma and Tristoma,
and by Nordmann* in those remarkable small
Entozoa inhabiting the aqueous chamber of
the eyes of some quadrupeds, the Diplosto-
mum, and in the Diplozoon. In the first of
these animals, the motion of fluid in the vas-
cular system is exceedingly obscure; but in
the Diplozoon (fig. 328), Nordmann saw, with

Fig. 328.

Diplozoon.

a high magnifying power, currents moving in
opposite directions in two sets of vessels (a, v)
placed on each side of both limbs of the ani-
mal. These vessels, termed external and in-
ternal, are said to terminate posteriorly in a
dilated bag, to which Nordmann gives the
name of receptacle of the chyle. The organs
of circulation of the Diplozoon differ, there-
fore, in this respect from those of the Planaxia,
to which otherwise they bear considerable si-
milarity; for, in the latter animal, the vascular
system appears to be entirely closed. Accord-
ing to Nordmann and Ehrenberg no contrac-
tions or dilatations of the vessels are visible.

Acalephe—In some of the Medusa tribe,
or Acalephe,. there appears to be no distinct
circulatory apparatus ; and we observe that in
these instances, the alimentary cavity is of
great extent and is often much ramified on the
surface of the animal.

In others there are distinct vessels with a

* Micographische Beitrage, p.69. Berlin, 1832.

CIRCULATION.

circulation of fluid within them. The distri-
bution of this very simple kind of vascular —
system was first discove Eschscholtz, who |
has described its form particularly in the Cestum
and Beroe. In the latter animal, it is stated
that eight arterial vessels and two veins unite
with a large annular vessel which surrounds the
mouth, and, according to Eschscholtz’s* conjec-
ture, another vascular ring, situated at the pos-
terior extremity of the body, forms the means
of communication between the arteries and
veins in that region. Branches pass from the
external or arterial vessels, and from the in-
ternal or venous vessels to the fins, which
organs seem to serve at once for respiration
and for locomotion. Although the motion of a
yellowish fluid containing globules has been
seen in these vessels, the complete circulation
does not appear to have been made out in
a satisfactory manner.

Infusoria.—Some kind of circulation is
stated to have been observed by Ehrenberg in
some of the Infusoria; but this is an observa-
tion which, with every confidence in the ac-
curacy of this celebrated microscopic observer,
we feel inclined to consider as liable to fallacy,
on account of the prevalence of various kinds
of ciliary currents in the interior of many of
these animals. |

Polypi.—We would extend the same remark
to the last kind of circulation to which we
shall allude, viz. those singular currents of
fluid, which were discovered by Cavolini and
recently observed by Mr. Lister in some of
the Polypiferous Zoophytes. According to
the latter observer, in each of the divisions
of the stem of the Tubularia indivisa, a cur-
rent of fluid carrying globules along with it
is seen proceeding up one side and down the
other. In various Sertularie, the direction of
the current becomes reversed from time to
time. Similar phenomena are to be observed
in Campanularie and Plumularie. The
striking analogy which these currents bear to
those occurring in the stems of some plants, as
Chara and Caulinia, seem to us to bring them
under another class of phenomena than those
of the vascular circulation of the higher ani-
mals. We do not, however, intend to enter
upon the consideration of this subject, as it
is already fully treated of under the article
Civta.

In concluding our notice of the simpler
forms of the circulatory organs, we would re-
mark that one of the great difficulties which
retards the acquisition of an accurate know- —
ledge of the function of circulation in the
lowest classes of animals, proceeds from our
inability to determine, whether currents moving
within enclosed spaces in these animals belon;
to the circulation of their blood and nutritious
fluids, or are connected with respiration, loec
motion, and other processes of their econom:
and this is an obstacle to the progress of |
investigation which from its nature we can
hope soon to see removed. oi

* System der Acalephen.

Berlin, 1829,
the article Acalephe,- p. 43. tae

j
,
:
|

which it is our intention to give.

from the obstructed vessel.

CIRCULATION. 655

In the Planaria, Medusa, some Entozoa,
and Polypi, the subdivided or ramified ceca
of the alimentary cavity (fig 328, I) must
obviously contribute to the effect of furnishing
a supply of digested matter to the different
regions of the body, and of thus rendering a
distinct vascular system in them to a certain
extent unnecessary. But in these simpler
kinds of animals, and even in those of them
in which distinct vessels have been discovered,

we cannot regard such scattered tubes as the

only principal means of distributing the nutri-

tious fluids to the different parts of the body.
‘They may assist in bringing this about; but it

is also necessary to suppose the oceurrence of

‘an interstitial movement or organic transuda-

tion of the fluids, in order to furnish to all
the parts the materials for assimilation.

II]. PHenoMeNna OF THE CIRCULATION AND
POWERS MOVING THE BLOOD.

In proceeding to the third division of our
subject, viz. the phenomena of the circulation
and the powers by which the blood is moved, we
would remark, that, however desirable it might
— in a systematic work of this kind to treat
of these two subjects under distinct heads, such
a separation would have the effect of detaching
inconyeniently the facts from the legitimate
conclusions which may be drawn from them.
We shall first state the phenomena and causes
of the motion of the blood which belong strictly
to the organs of circulation themselves, and
afterwards shall treat of various circumstances
connected with the other functions by which
the circulation is modified. In this view it is
our chief object that the facts adduced should
bear upon the explanation of the motion of the
blood in the human body, but from the nature
of the investigation the facts themselves must
be drawn chiefly from experiments made upon
the lower animals. Of course those experi-
ments and observations which have been made
on Mammiferous animals have most value in
relation to such a view of the function as that
The order
which we shall follow is founded on the course
which the blood pursues. We shall treat, 1,
of the passage of the blood through the heart ;
2, of its flow in the arteries; 3, of its. passage
from the arteries to the veins through the ca-
pillaries; and 4, of its flow in the veins.

1. Flow of the blood through the heart.—
That the muscular contraction of the heart is,
in man aud in all animals in which this organ
exists, the principal source of the power by
which the blood is propelled in its course,

seems to be satisfactorily proved by the facts,

that whenever the action of the heart ceases or
is impeded, the whole circulation ceases, and
that, when an obstruction prevents the action
of the heart from reaching the blood in any of
the bloodvessels, the flow of blood ceases almost
instantaneously in a!l the branches proceeding
The constant and
regular persistence of the contractions of this
muscular organ from the commencement of life
to its termination, the early period at which it
begins to act in the foetus, viz. before any re-

gular circulation of blood takes place, and the
existence of a heart or some similar contractile
organ in all those animals in which a regular
circulation of blood or nutritious fluids occurs,
are confirmatory of the view suggested by direct
observation and experiment. Under the article
Heart will be found a detailed account of the
structure and functions of this organ; in this
place we shail only state, in as few words as
we can, what seems to have been best ascer-
tained regarding its action, in so far as this
appears to have a reference to the force of im-
pulsion and direction which it communicates
to the blood.

The action of the heart may be observed by
opening the chest of a living animal, or for a
short time in one immediately after death, or
best of all in an animal deprived of sense and
motion by poison, and in which artificial respira-
tion is maintained ; it has also been seen in chil-
dren born with ectopia cordis, or in persons in
whom from accident a part of the heart has
been exposed to view. When observed under
one or other of these circumstances, the action
or contraction of the whole heart is seen to
consist of two motions, viz. 1, the contraction
or systole of the auricular part, and 2, that of
the ventricular part of the organ. The con-
traction of the auricle immediately precedes
that of the ventricle and seems to be continued
into it, and the systole of each cavity is imme-
diately followed by its diastole or relaxation.*
After the relaxation of the ventricle, there is a
period of repose, or a pause in the action of
the heart, during which motion seems to be
nearly suspended. At the moment when the
systole of the ventricle takes place, the heart
appears to be diminished in all its dimensions,
and exactly at the same instant of time, the
apex is seen to be moved towards the sternum,
in whatever position the animal is placed.
This tilting forwards of the apex gives the
heart a pulsation against the ribs that can be
felt externally. This pulsation probably de-
pends on the arrangement of the muscular
fibres of the heart, as the raising of the apex
occurs when the heart is removed from the
body and is empty of blood. At the time
of the systole the heart is thicker and more
conical in its figure than during the diastole;
when held in the hand it feels hard, and the
ventricles appear to have propelled the whole
of the blood out of their interior, as far as one
can judge from the great diminution in their
size. In the inferior animals, as Reptiles and
Fishes, its colour is lighter from the expulsion
of the blood. During the relaxation or dias-
tole, the heart appears to fall away from the

* In some of the lower animals, in the fetus
of the Bird at an early period, and in warm-
blooded animals when the action of the heart is
weakened, as at the approach of death, the con-
traction is seen to begin in the venous sinus of
the auricle, extend through it to the ventricle, and
from one part of the ventricle to another in a gra-
dual manner. In the Batrachia, the contraction
begins in the veins, and after passing through the
auricle and ventricle, extends into the commence-
ment of the aorta.

656
chest, its parietes become flaccid, and it as-
sumes a ned form. The pulse in the

arteries, which is in truth nothing more than
the communication of the impulse of the heart
along the blood in these vessels, corresponds,
at least in the larger arteries near the heart, very
exactly in time with the ventricular systole and
the beat on the walls of the chest. The action
of the heart is accompanied by two sounds,
that can be heard on applying the ear to the
cardiac region. The first of these sounds is
synchronous with the systole of the ventricles,
the second with their diastole; the second
follows the first immediately, and is succeeded
by an interval of silence. Of the space of
time in which a full action of the heart is
completed, the systole of the ventricle occu-
pies nearly a third, the systole of the auricle
less than a quarter; the dilatation of the ven-
tricle and repose taken together must be
effected in the remainder.

The heart, from its structure and action, may
justly be considered as a living or self-moving
double forcing-pump, which is continually
filled at one part and emptied at another.
During one-third of the time of a complete
action of the heart, the blood in the arteries is
impelled onwards by the direct impulse of the
ventricles at their systole. During the other
two-thirds of the time, while the ventricle is
inactive, the communication between its cavity
and the great arteries is stopped by the closure
of the semilunar valves, and the blood must,
herefore, at this time be propelled by the
elastic and other forces of the arteries them-
selves. But the heart continues to receive
blood from the veins during a longer time than
it gives out any of that fluid, for the auricles
offer a resistance to the entrance of blood du-
ring only a space of less than a quarter of the
time employed in a complete action of the
heart, and the blood is continually impelled
into the auricles as well as the ventricles du-
ring the whole time that these cavities are not
contracted, although more blood enters the
auricles immediately after their relaxation, and
more is propelled into the ventricles just be-
fore their contraction than in the rest of the
time.

During the systole of the ventricles, while the
stream of blood issues from their cavities into
the first adjoining parts of the large arteries,
the folds of the semilunar valves are laid close
to the inner side of these vessels. As soon as
the contractile force of the ventricles ceases,
the free edges of the semilunar valves are
brought towards the middle of the vessel, and
applied firmly against one another so as to
close the ventriculo-arterial orifices: this is
effected by the pressure of the column of
blood acted upon by the elastic coats of the
arteries, assisted perhaps by the elasticity of
the borders of tlie valves themselves and by
the change of position consequent on dilatation
of the ventricles.

During the systole of the ventricles, the
auriculo-ventricular or tricuspid and mitral
valves are closed, so as to prevent in a great
measure regurgitation of the blood from the

CIRCULATION.

ventricles into the auricles. When the ven-—
tricles are in the relaxed state, the valves
are opened by the stream of blood flowing
from the auricles. The circumstance that
the free margins of the mitral and tricuspid
valves are bound down to the inner walls
of the ventricles by the tendinous cords at-
tached to the fleshy pillars, and that, by the
contraction of these pillars, the free margins
of the valves mnst 5 pulled further down
into the ventricle than in the relaxed state,
has occasioned to some a difficulty in under-
standing their action, and led them to suppose ’
that the columne carnez must necessarily be
relaxed at the time of the ventricular systole, ;
and that by contracting while the ventricle is
in its diastole, the fleshy pillars contribute to
open the valves. The direct observation of
the contraction of the columnz carnez in the
heart of an animal taken from the body, and >
an attentive observation of the structure of .
these valves, from which it appears that the |
tendinous cords passing to opposite flaps of |
the valves frequently come from the same
columne carnee or point of attachment in the :

;

ventricular paries, sufficiently prove that these
fleshy pillars actually contract at the same mo-
ment as the rest of the parietes of the ven-
tricles, and that their contraction, besides
drawing the free margins of the valves down-
wards into the ventricles, must also tend to
make them approach one another more nearly ;
and we are therefore entitled to form the con-
clusion, that, while the tendons serve to fix
the valves, the action of the columne carnez is
to draw these down so as to allow the blood
to pass behind them, and to press them to-
gether and close them in the same manner as
the semilunar valves of the aorta and pulmo-
nary artery are shut. “
The apparently greater facility of the en- ‘
trance of blood into the heart at one time than j
at another, has given rise to the opinion enter- a
tained by some physiologists that the dilatation
of the heart is, like’ the contraction, accom-
panied with the production of a new force,
which draws the blood from the veins towards
the heart. Some who regard muscular elon-
gation asa source of new power have gone so
far as to suppose that this force is even greater
than that accompanying contraction, but it is
manifest that such a view is opposed by every
thing we know of muscular action, which leads
to the belief that the shortening of muscular
fibre ought alone to be considered as an active, —
and the subsequent elongation as entirely a
passive change. Others suppose the ventricles
of the heart to dilate in consequence of elas-
ticity, in the same manner as a bag of caout- _
chouc does after being compressed with some _
degree of force. Attempts have even been
made to measure the extent of the force pro- —
duced during the dilatation of the ventricle
by endeavouring to ascertain the weight whic
is displaced by this motion of the heart. W
would not wish to be understood to deny
possibility of the heart’s exerting some sli
force in this way during its dilatation, but
appears very clear that a measurement of the

a ee a

*
a

I
7
;
,

CIRCULATION. 657

kind referred to must be so difficult as to be
almost useless; indeed, it is very probable
that some have mistaken the contraction for
the dilatation, and we shall afterwards find
that the power of suction, exerted by the heart
on the blood, as measured by the force with
which the veins are emptied, is very small
indeed. It is clear that the blood driven on
from behind by a propelling power, or flowing
through parts which are pressed upon by
neighbouring organs, must enter the heart
more easily during the relaxation of the pa-
rietes of the ventricle than at any other period
during the heart’s action, so as to give rise
to an appearance of suction, but direct expe-
riments make it sufficiently obvious that the
force of impulsion from behind is almost the
sole cause of the entrance of the blood from

the trunks of the great veins into the cavities.

of the heart.

In order to form an estimate of the time in
which a given quantity of blood may pass
through the heart, or of the time in which the
whole quantity of blood contained in the body
would take to pass through the heart, several
data are required which are not yet furnished
by accurate experiments. In the first place,
we must know the average quantity of blood
contained in the body, and, in the next place,
the quantity which is evacuated from the heart
at each stroke or systole of the ventricles.

With regard to the first of these points,
a number of calculations have been made
which vary greatly in their results. Animals
have been bled to death by the section of the
larger bloodvessels, and the quantity of blood
lost has been measured. ‘The quantity of
blood lost in this way seems to have varied
from 1-10th to 1-30th of the weight of the
whole body, and Dr. Moulins, who formed
his estimates from experiments of this kind,
rated the quantity of blood in the human body
at eight or nine lbs. only, or 1-20th of the
weight of an average sized man, taken at 150
or160lbs. But it is obvious that when one of
the larger bloodvessels is opened, from the
suddenness of the flow, the animal faints or
dies before the whole or even a considerable
whey of the blood has been lost; and it

as been ascertained from numerous obser-
vations, that when the blood flows more gra-
dually and from small vessels, as occurs in
hemorrhages from the nose, stomach, rectum,
or uterus, a proportionally much greater quan-
tity of blood may be lost than occasions death
in animals experimented upon by the section
of the larger arteries or veins. Instances are
on record in which from ten to twenty Ibs.
and even greater quantities of blood have
flowed from the human body within twenty-
four hours.* We feel inclined on these
grounds to coincide with the estimate formed
by Haller, that the blood forms about a fifth of
the weight of the body, or equals from twenty-
five to thirty Ibs. in a man of the average
weight of 150 lbs. It is obvious that this

* See Haller’s Elementa, and Keil! on the An.
Econ,

must vary in different individuals from other
circumstances besides a difference of stature.
In the young, the quantity of blood is con-
sidered to be greatest. Of the whole of the
blood contained in the body, it is estimated by
Haller, and probably with accuracy, that four
parts are contained in the arterial and nine in
the venous system.

In endeavouring to estimate the quantity
of blood which passes through the heart in a
given time, we must find the capacity of the
cavities of the heart, we must ascertain whe-
ther the cavities on the two sides are of the same
size, and, as it is almost impossible to measure
the quantity of blood evacuated from the heart
at each stroke, we must find to what extent
the ventricles empty themselves during their
systole. It is obvious that, so long as the
circulation is uniform and no local accumu-
lation of blood takes place, the same quantity
of blood must pass out of the ventricles into
the larger arteries which enters by the veins,
and for the same reasons, that the quantity of
blood passing through the right and left cavi-
ties of the heart must be exactly equal. The
circumstance that an equal quantity of blood
passes out of the right and left cavities of the
heart during their systole does not entitle us
to conclude that the capacity of the different
auricles and ventricles is the same, because
any one of them during its systole may be
more or less completely emptied than the rest,
and a regurgitation obviously takes place from
some of them, so that the whole blood which
they contain is not propelled in its onward
course. According to some anatomists the au-
ricles are larger in capacity than the ventricles,
probably in the proportion of three or two and
a half to two, and the auricles are by no means
completely emptied during their systole. An
opinion has very generally prevailed that the
cavities on the right side of the heart are some-
what larger than those on the left. There is no
doubt that in making measurements of the re!a-
tive capacity of the two sides after death, it is
most frequently found so; but it is obvious that
some have very much overrated the difference,
and there is much reason to believe that the
greater capacity of the right auricle and ven-
tricle depends in part on the accumulation of
blood which generally takes place in most
kinds of slow death in the pulmonary arteries,
and in part also upon the greater thinness and
consequent distensibility of the right ventricle.
In men dying suddenly, and in animals killed
purposely, in which the pulmonary artery is
opened so as to allow of the free egress of the
blood from the right side of the heart, the
capacity of this ventricle is not greater than
that of the left, and the proportions of the
capacity of the two sides of the heart usually
found after slow death are sometimes reversed
when a ligature is placed on the aorta and the
pulmonary artery is opened.* Most authors
seem to have agreed to follow the estimate of
the capacity of the ventricles given by Hales
in his Medical Statics. This author esti-

Tis Sabatier.

658

mates the capacity of the left ventricle at
14 oz. fluid measure, and that of the right at
2 oz. The contemplation of the muscular
structure of the left ventricle, and the great
diminution in size it undergoes during its sys-
tole, would induce us to conclude that it must
be completely emptied during the contraction,
and that there cannot remain any blood even
among the columnez carnee. The right ven-
tricle does not appear from the quantity of its
muscular substance to be so well suited to be
emptied, but its position round the left must
assist considerably in the diminution of its
size during its systole. In some cases of sud-
den death in healthy persons, both ventricles
have been found completely empty.

The whole of the blood issuing from the
ventricles into the first parts of the great arte-
ries is retained within these arteries by the
action of the semilunar valves, and it would
appear that in the healthy condition the adap-
tation of these valves is such that very little
if any blood regurgitates or flows backwards
into the ventricles. At the time that the auri-
cles contract, a very different phenomenon
presents itself, for while a certain quantity of
the blood from the auricles passes onwards
into the ventricles, some is driven back into the
orifices of the great veins. This venous re-
gurgitation is particularly evident in the veins
connected with the right side of the heart, the
orifices of which have no valves or very im-
perfect ones ; and it gives rise to a pulsation in
their larger branches, synchronous with the
systole of the auricle, as may be seen in most
thin persons in the jugular vein at the lower
part of the neck. It would appear that upon
some occasions, even in the state of health,
a certain back stroke from the ventricles also
is perceptible in the veins, and Hales was of
opinion that some of the blood (half an ounce)
from the right ventricle flowed back into the
auricle during each systole of the ventricle.
It must be apparent that immediately after the
auricle has ceased to propel its contents into
the ventricle, and just when the systole of the
ventricle begins, the column of blood extend-
ing from the ventricle into the auricle through
the auriculo-ventricular orifice must be con-
tinuous, and the pressure of the ventricular
systole must thus be transmitted upwards until
the valves flap together and close that opening.
Accordingly, in some persons in health, a ve-
nous pulse, synchronous with the ventricular
systole, is occasionally seen or felt in the jugu-
lar veins, but this appearance is much more
commonly a sign of disease; for the venous
pulse which is synchronous with the ventri-
cular systole is much increased when an ob-
stacle presents itself to the free flow of blood
through the pulmonary artery, or when from
ossification or other morbid alteration, the auri-
culo-ventricular valves do not close accurately
the passage in which they are placed.

We may conclude, from the observations
above alluded to, that on an average each of the
ventricles of the heart gives out nearly one ounce
and a half at each stroke; and we may now
state the general calculation of the time that

CIRCULATION.

blood in the body at 28 lbs.; and let us sup-

the blood takes to move through the heart,
which is generally founded upon the above
data. Let us suppose the heart to beat seventy-
five times in a minute, which is nearly the ave-
rage number of pulsations in a healthy man in
the prime of life, and assume the quantity of

pose that 14 oz. of blood is expelled from each
ventricle into the great arteries connected with
them, then 1120z. or 7 lbs. of blood would
pass through each ventricle in a minute, and
28 lbs. in four minutes; or in three minutes,
if the quantity of blood passing through the
ventricles at each systole be estimated at two
ounces, i.e. a quantity of blood equal to that
which we conceive to be contained in the
whole body, would flow through the heart in
the short space of four minutes, and this quan-
tity would run the same course fifteen times in
an hour. We must guard against conceiving,
on the one hand, that this calculation affords
any accurate measure of the quantity of blood
which actually passes through the ventricles in
a given time, for there are innumerable circum-
stances which tend to cause this quantity to
vary to a considerable extent; and on the other
hand, it must at all times be borne in mind
that we can, from such calculations, estimate
only the velocity of the blood in the heart itself,
or the time which a certain quantity of blood
takes to pass through its cavities, but that we

are not furnished with any measure of the time
that the whole of the circulating quantity of 1
blood actually takes to pass through its course,

for the length of the courses through which the
blood has to pass in different parts of the vas-
cular system varies to such a degree, that in
some places, as for example in the bloodves-
sels of the heart itself, the return to the heart
must be effected in less than half the time
employed by that which is transmitted to the
extremities. On comparing the longest or
shortest calculations of this kind made by dif-
ferent authors, we shall find that the time of a
circulation is made to vary from six minutes
and a half to one minute.

We shall not at present enter upon the con-
sideration of the force with which the blood
issues from the left ventricle of the heart, as
the experiments by which this force is deter-
mined being made upon the arteries, come
more suitably to be treated of under the arte-
rial circulation.

2. Phenomena of the arterial circulation. —
In proceeding to consider the phenomena and
causes of the flow of blood through the arterial
system, we purpose to treat of, 1st, the velocity ;
2d, the force of the blood in the arteries; 3d,
the nature of the arterial pulse; 4th, the vital
properties of the arteries; and 5th, the influence —
exerted by this class of bloodvessels on the cir- —
culation. We shall find that, in this part of —
our subject, the difficulty of becoming ac-
quainted with the immense variety of circum-_
stances capable of modifying the flow of the
blood, has prevented the explanation of phe
mena which are in themselves sufficiently s
ple and apparent. In our remarks upon th
above-mentioned topics, we shall endeavour to

Se

oe,

=). = = Pe ee

CIRCULATION. 659

refer the phenomena of the circulation, as far
as we can, to hydraulic principles, which, when
correctly applied, must form the only sure
guide in conducting a physiological inquiry of
this nature.

The flow of the blood, as it is expelled from
the left ventricle, may be said to be intermit-
tent, for it moves only at the time of the ventri-
cular systole. Farther on in its course, in the
larger as well as the middle sized arteries, the
flow of blood is remittent, or is more rapid
after each beat of the heart, and by the time it
arrives at the capillary vessels and commence-
ment of the veins, the velocity is rendered per-
fectly uniform. The effect, therefore, produced
by the arterial tubes is to convert an intermittent,
first into aremittent, and afterwards into a uni-
form force. When an opening is made into
one of the larger arteries, the jet of blood which
issues is regularly increased in velocity at every
systole of the ventricle. In the very small ar-
teries, this acceleration of the stream becomes
less perceptible. We know that it has altoze-
ther disappeared in the smallest vessels or ca-
pillaries, from microscopic observation of the
flow of the blood in them, and the uniformity
of the velocity of the stream in the veins is
clearly shewn in all instances in which a vein
is opened, as in the common operation of
bleeding from the arm.

Various circumstances shew that in the living
body the blood forms an uninterrupted column
of fluid in the bloodvessels, and that the whole
vascular system is kept in a state of forced dis-
tension by the reiterated impulses communi-
cated to the blood by the ventricular contrac-
tions. Besides the general fulness of the blood-
vessels and their connection with the heart, we
may mention as proofs of the distended state of
the vascular system, the facts, 1st, that, on
opening any of the bloodvessels, the blood
issues with greater force at the first moment
than afterwards ; and 2d, that when we imitate
the propulsion of the blood through the arteries
and veins by artificial injection of fluids in a
dead animal, we observe that the jet from an
opened vessel continues to flow for some time
after we have ceased to drive the piston of the
syringe. The arteries being much stronger
than the veins, re-act with greater power than
they do against the distending force of the
heart. Were the arteries rigid tubes, it is ma-
nifest that in a given time just as much blood
would pass from their remote extremities into
the commencement of the veins, as enters them
by the mouth of the aorta; ‘but the arteries
must be fuller at one time than another, for the
quantity of blood expelled from the ventricle at
each systole, must pass suddenly into the first

tt of the aorta, while an equal quantity of

lood, which must necessarily pass from the
remote arteries into veins, as it moves uni-
formly, must employ the whole period of
time occupied by a complete action of the
heart in its passage; and consequently it is
manifest, that the arterial system must be fuller
just after than immediately before the contrac-
tion of the ventricle. The arteries are distensi-
ble and elastic, they yield a little to every suc-

cessive stroke of the ventricle, and during the
diastole they re-act by their elasticity, so as to
keep up the flow of blood. We have already
said, in speaking of the heart, that the muscular
contraction of that organ is the chief, if not the
only source of the power propelling the blood.
It is only in those arteries which are nearest to
the heart, however, that the blood can be said to .
be propelled by the direct impulse of the ven-
tricle, for in the rest of the arterial system, the
progression of the blood is immediately effected
by the elastic power of the arteries, called into
operation in consequence of their distension by
the action of the heart. In the experiments of
artificial injection of the bloodvessels in dead
animals already mentioned, as long as we con-
tinue to drive the piston of the syringe, and to
propel fluids through the arteries into the veins,
the arteries are kept in a state of forced disten-
sion; in consequence of this, the fluid issues
from an opened artery with a jet accelerated
after each successive stroke of the piston, and
continues to flow for some time after the pro-
pelling power has ceased to act. The unifor-
mity of the stream of fluid from the veins,
which occurs in the same experiment, is a proof
that the continued flow of blood in these tubes
may, in the living body, be owing to an impul-
sion from the heart, transmitted by the arteries,
and that it is caused by the elasticity of the
coats of the vessels themselves.

a. Velocity of the blood in different arteries.
The space of the aorta filled up by the blood
propelled from the ventricle at each systole,
divided by the time occupied in its propul-
sion, constitutes the velocity of the blood in
the first part of the aorta. The diameter of the
aperture of the aorta at the ventricle being taken
as On an average 1°12 of an inch,* its area would
be one square inch, and consequently 13 oz.
which equal 2°45 cubic inches of blood, would
occupy a little more than 2°5 inches of the aorta,
supposing its size to be for such an extent of a
uniform diameter. As it is satisfactorily ascer-
tained by actual measurement, that the blood
contained in the smaller vessels is in much
greater quantity than that in the larger trunks ;
or, in other words, as the capacity of the smaller
vessels taken together is greater than that of
the larger, it will at once be apparent, that the
velocity of the blood must diminish in passing
from the larger to the smaller vessels. The
arterial and venous vessels may in fact be re-
garded as two hollow cones, curved so as to be
joined at their apices to the heart, and at their
bases to one another. The veins, being more
numerous and wider than the arteries, must be
represented by a wider cone. The section of
these cones at any place is supposed to give
the combined area of the section of the vessels
at a corresponding distance from the heart.

The estimates made by different authors of
the relative velocity of the blood in the larger
and smaller vessels, differ in a great degree,

* The aperture of the aorta is somewhat less
than one inch in diameter in most persons; we
may, however, adopt the above estimate of its size,
as the sinus of the aorta is much wider than its
aperture,

660

and are exceedingly unsatisfactory. Haller,
who fully admitted the greater capacity of the
smaller arteries, and allowed that the flow of
the blood must therefore, from hydraulic prin-
ciples, become less rapid in passing from the
trunks to their branches,—a proposition which
he illustrates by comparing the stream of blood
_ in its passage to a river which enters a lake,—
was yet inclined, from the result of his actual
observations, to deny that the velocity is much
less in the smaller than in the larger arteries.
Spallanzani, although admitting more explicitly
still than Haller the necessity of such a retarda-
tion, seems to have met with the same difficulty
in reconciling theory with his attempts to mea-
sure the velocity of the blood in the small ves-
sels: and both these authors state, that although
the circulation was in general comparatively
slow in the web of the frog’s foot, still in many
instances in this situation, and more frequently
in the mesentery, they were unable to detect
any difference in the rapidity of the flow of the
blood in the larger and smaller arteries.*

Hales, again, states as the result of his ob-
servations and measurements, that the velocity
of the blood in the smallest capillaries of the
abdominal muscles of the frog, is so small as
one or one and a half inch in a minute; and,
from the attempts which we ourselves have
made at these measurements, we feel inclined
to agree with the statement of this able experi-
menter, having, upon several occasions, ascer-
tained that in those capillaries which admit
only two globules of blood, the velocity is not
greater than the hundredth part of an inch in a
second; but it seems doubtful whether in all
the capillaries the velocity is so small as in
those just alluded to, and in the larger capillary
vessels of the diameter of six globules, when
no unnatural obstruction to the circulation in
the limb occurred, independently of the diffi-
culty of fixing the eye upon any globule in such
a way as to trace its progress along the vessel,
the velocity has always appeared so great as to
prevent the possibility of measuring it; and we
are at a loss to conceive in what manner Haller
made the comparison he speaks of between the
velocity in the larger and smaller arteries. By
means of the microscope, it is easy to see that
the velocity is greater in the small arteriés than
in the corresponding veins, which are both
more numerous and considerably larger than
the arteries.

The results of actual observation of the flow
of the blood and of the measurement of the
relative capacities of different arteries, afford as
yet very unsatisfactory data upon which to
found an estimate of the relative velocity of the
blood in the trunks and branches of the arte-
ries. In the absence of more direct means of
calculation, an approximative estimate may be
made in another way, viz. by comparing the
quantity of blood which occupies a known
space of the larger vessels with the whole quan-
tity of blood contained in the body.

We have already seen that the whole blood

* Haller appears to mean here arteries of consi-
derable size.

CIRCULATION. ‘

junction with the heart; a very simple calcula-

in the body may be estimated at nearly thirty
pounds: now, let us suppose the aorta and
pulmonary arteries, together with their return-
ing veins, to form a continuous tube of the
length of the two courses of the blood, in the
systemic and pulmonic circulations, and of the
same diameter as these vessels at their point of

tion shews us that such a tube is capable of
holding only about six pounds and a quarter,
or less than a fourth part of the whole blood
of the body ; or in other words, were the aggre-
gate capacities of the small vessels no more
than equal to that of the larger, they would be
capable of holding only a fifth of the blood
contained in the body.

The velocity of the blood in the commence-
ment of the aorta may be considered as two-
and a half inches in a second, for this is the
Space occupied by all the blood which is pro-
pelled into the aorta from the left ventricle in
that time, and according to the arbitrary modes
of estimating the relative capacity of the aorta
and its branches here employed, the velocity
of the blood in the aortic capillaries generally,
might be considered as one-fourth of that in the
commencement of the aorta, or nearly half an
inch in a second, a result widely different from
that obtained by Hales.

Attempts have also been made to estimate
the velocity of the flow of blood, by ob-
serving the time which certain substances,
when introduced into one part of the vascular
system, take to pass to another. The most
remarkable series of experiments of this na-
ture with which we are acquainted were per-
formed by Hering.* This author states that
he has been able to detect prussiate of potassa,
which he had introduced into one of the jugu-
lar veins of a horse, in the blood drawn from
the opposite jugular vein in the space of from
twenty to thirty seconds; and he has formed 5
the conclusion from this experiment that the :
prussiate of potass, in order to gain the jugu- .
lar vein on the opposite side of the body, had
passed in this remarkably short space of time
through the whole course of the double cireu- 4
lation: that it was first carried to the heart, ~
then passed through the pulmonary arteries
and veins, and returned to the heart, from
which it must have been transmitted through
the ultimate ramifications of the systemic ar-
teries before being brought back by the veins,
in which it was found on the opposite side of
the body. Hering states, as the result of other
experiments of a similar nature made upon
different bloodvessels, that the prussiate of
potassa passed from the jugular vein to the —
saphena vein in twenty seconds; to the mas- —
seteric artery, in fifteen to twenty seconds; to
the external maxillary artery, in ten to twenty-
five seconds ; to the metatarsal artery, in twenty —
to forty seconds. j a

We consider these curious experiments as
important in many points of view, but do no
feel inclined to concur in the conclusion
duced from them by their author, that t

eee. ee

= a

CIRCULATION.

circulation of the blood, rapid as it may be,
takes place in this remarkably short space of
time, and we are disposed to suspect that the
experiments themselves are liable to several
sources of fallacy. The tendency of the prus-
Siate of potass to permeate the textures of the
body, more freely than any other substance
known, has been proved by many expe-
riments, and it is therefore necessary that
Hering’s experiments should be performed with
some other substances, before they can be re-
garded as a correct means of estimating the
rapidity of the circulation. |

The velocity of the blood is generally be-
lieved to be greater in the pulmonic than in
the systemic circulation,—an opinion founded
chiefly on the supposed less capacity of the
vessels belonging to the pulmonary trunks.
Actual measurements of the velocity of the
blood in the capillaries of the lungs of cold-
blooded animals by Hales, Spallanzani, and

others, would seem to give support to this

view, but it must at the same time be re-
collected that the course through which the
blood passes in the pulmonary or lesser circu-

. lation, is considerably shorter upon the whole

than that of the systemic or greater,—a circum-
stance which must diminish to a certain extent
the disproportion in the velocity.*

b. ) oe of the blood in the arteries and force
of the heart—Another interesting inquiry con-
nected with this subject relates to the force
with which the blood is impelled in the arte-
ries, and the calculations that have been made
of the power of the heart itself, from the ob-
servation of the force of the blood in the arte-
ries. The experiments made with a view to
discover these forces appear sufficiently simple
in their nature; but the calculations founded
upon the experiments have differed so widely,
as to have furnished a plausible pretext for
throwing ridicule on the application of physical
laws to the living animal functions.

As the arteries and other vessels are kept
distended with blood by the action of the
heart, it follows that were they rigid tubes,
the force of the heart would, in accordance
with the laws of propagation of pressure
through fluids, be transmitted without loss
through the whole column of blood in the
arteries at one and the same moment: but in
consequence of their yielding to distension,
the force of the heart operates upon the blood
only through the elastic reaction of the coats

_ of the arteries.

When an opening is made into one of the
larger arteries, the blood issues with force, and

spouts to some distance, but the height to

* In reference to the above calculations, it must
also be kept in mind, in the first place, that the
estimate of the velocity of the blood in the pul-
monic circulation in the frog can scarcely with
seuapentg be applied to man, seeing that in the
rog the pulmonary artery is only a branch of the
aorta; and, in the second place, that in animals
with a double circulation, although the quantity
of blood which leaves both sides of the heart at
each systole be equal, it does not necessarily follow
that the whole blood which circulates through the

system should in the same time pass. through the
lungs.

661

which the blood rises when allowed to escape
from a simple aperture in an artery varies from
many accidental circumstances, and cannot
therefore be taken as affording an accurate
measure of the force with which the blood
moves within the vessels.

Hales seems first to have investigated this
force in a more accurate and experimental
manner, by observing the weight which the
blood in one of the arteries of a living animal
is capable of sustaining within a tube adapted
to it. He remarked that the blood issuing
from a simple aperture in the carotid artery of
a horse and directed upwards did not rise
above three feet,* but that when the blood was
allowed to pass into a long glass tube adapted
to the same artery it rose very quickly toa
much greater height, as to nearly ten feet in
some of the experiments. Hales performed
similar experiments on the arterial flow in
sheep, oxen, dogs, and other animals, and
after observing for each the pressure which the
blood in the arteries is usually capable of ex-
erting, he endeavoured to compute the pres-
sure of the blood in the arteries of man, by
a comparison of the size of his whole body or
heart and bloodvessels with those of the other
animals. The pressure of the blood in the
aorta of the horse being considered as eleven
pounds, Hales estimates in the way above-
mentioned the force of the blood in the human
aorta at 4 lbs. 6 0z.; seven and a half feet
being the height to which he supposed that the
blood would rise in a tube connected with the
larger arteries of a man.

These experiments of Hales shewed in a
very clear manner, that the height to which
the blood rises in one of the larger arteries
affords us the means of ascertaining directly
the amount of pressure which the stream of
blood impelled by the heart through the arte-
ries is capable of exerting at any part of the
arterial system, or in other words it gives us a
measure of the statical force of the heart as it
operates through the arterial tubes.+

According to a well-known law of physics,
the heart must be pressed upon in every part
of its internal surface by the column of blood
which it has raised; so that by multiplying
the area of the internal surface of the ventricle
into the height of the column of blood sup-
ported in the tube connected with an artery,
we shall ascertain the pressure which acts
backwards on the inner surface of the heart.
Hales estimates the inner surface of the ven-
tricle of the human heart at fifteen square
inches, and multiplying the pressure of a co-

* This experiment we have repeated with Mr.
Dick’s assistance.

+ These experiments, as well as others subse-
quently performed, demonstrate the importance of
confining our researches in an inquiry of this nature
to the estimation of the statical force operating in
the organs of circulation, as the only useful ob-
ject of such calculations,—the propriety of which
is also sufficiently apparent from the extraordinary
results of the attempts to estimate the dynamical

ower of the heart or the whole force generated
in that organ by muscular contraction, by Borelli
and Bernouilli, the first of whom calculated this
force to equal 180,000, the second 3,000 Ibs.

662

lumn of blood of seven feet and a half high
into the area of the inner surface of the heart:
he hence calculates the pressure on the in-
ner surface of the human heart to be nearly
514 lbs. The pressure on the interior of the
horse’s heart he estimates at 113 lbs. upon
similar principles.

As pressure applied in any direction toa
fluid column is equally transmitted through all
its parts, and as the blood in the arteries forms
continuous columns which all branch off from
the aorta, it might a priori have been con-
cluded that the force of the blood must be the
same in all the arteries of any considerable
size. Hales, though he does not state this
proposition very explicitly, seems yet to have
taken it for granted; for, in estimating the
pressure of the heart, he takes into account
merely the height of the column without re-
ference to the size of the artery. We shall
find this proposition to be satisfactorily proved
to be correct by direct experiments subse-
quently performed.

The experiments of Hales were liable to two
principal objections: 1st, that the coagulation
of the blood in the long glass tube adapted to
the artery must have prevented its free motion ;
and, 2nd, that the length of the tube, besides
giving rise to the necessity of frequently re-
moving it and various other inconveniences,
must have occasioned a considerable loss of
blood in filling from the arteries of small ani-
mals. Both these sources of fallacy have been
provided against most successfully by M.
Poiseuille,* an ingenious ex-
perimenter of Paris, who, by
the adoption of a simple con-
trivance, has been enabled to
measure with great accuracy
the arterial pressure of the blood,
and has thus confirmed and
extended the interesting re-
searches of Hales.

The instrument employed by
Poiseuille, to which he gives
the name of Hemadynamome-
ter, (fig. 329,)
consists of a bent
glass tube of the
ti form here repre-
Bla sented, filled with mercury in
the lower bent part (a, d, e).
The horizontal part (b), provided
with a brass head, is fitted into
the artery, and a little of asolu-
tion of carbonate of soda is
- interposed between the mercury

~ 329.

Wop

peeeees

and the blood which is allowed
to enter the tube for the pur-
pose of preventing its coagula-
tion. hen the blood is al-
lowed to press upon the fluid
in the horizontal limb, the rise
of the mercury towards (c)
measured from the level to
which it has fallen towards (d)
gives the pressure under which
the blood moves.

* Magendie’s Journal, vols. viii. & ix. Breschet’s
Repert. d’Anat. et de Physiol. 1826.

PUOVUL MAT OOADUCUSUEIAGUUUONONNOLDLQDOQGOOUOQOQEUEQGOEOTAMGASUCLERIOO CLA TNLL

PPTL TTT

Poiseuille’s He-
madynamometer.

CIRCULATION.

One of the most important facts established —
by Poiseuille’s experiments is, that the pressure’
of the blood is within certain limits nearly the
same in arteries of very different calibre and
at different distances from the heart; as proved
by the rise of the mercury of the hemadyna-
mometer to nearly an equal height when this
instrument was connected with the iliac, caro-
tid, radial, facial, and other arteries in some
of the lower animals. It is hence apparent,
that, in order to ascertain the whole amount

of force with which the blood is propelled +

in the aorta, or the statical force of the
heart itself, it is sufficient to measure by
means of the tube the momentum of the
blood in any one of the arteries. Poiseuille
estimates the force with which the blood is
propelled in the commencement of the aorta
in man at 4 Ibs. 3 0z.,—a result which agrees
remarkably with that obtained by Hales.*

Poiseuille, however, considers the pressure
backwards within the heart to amount to 13 Ibs.
only, as he calculates this in a different way
from that followed by Hales, viz. by multi-
plying the pressure of the blood in the aorta
into the surface of a plane passed through the
base and apex of the left ventricle,—a mode
of calculation which it appears that Dr. Hales
had not lost sight of; for, at page 21 of the
work on Hemastatics, he proposes it as the
“‘ means of estimating the force of the blood ~
which the muscular fibres of the ventricle must
resist.”

Poiseuille estimates the force with which the
blood moves in the radial artery of man at four
drachms.

Hales had remarked that the blood in the
tube connected with an artery rose regularly a
little way at each systole of the ventricle, and
remained always somewhat higher during the
straining of the animal, that is, while the
muscles of expiration were in action. These
phenomena, known to Haller, were demon-
strated experimentally by Magendie, and re-
ceive a still more decided confirmation from
the experiments of Poiseuille made with the
hemadynamometer.t

We would here remark that, it having been
shewn by the above-mentioned experiments
that the force of the heart is sensibly the same
in the trunks and larger branches of the arte-
ries, it is manifest that the angles of rami-
fication and the friction of the blood against
the sides of the vessels can give rise to very little
if any diminution in the force of the heart
transmitted by the elasticity of the arterial
parietes. We shall afterwards see that the
case is very different in the smaller vessels.

We would also call the attention of the —
reader to an interesting application of the fact —
of the complete transmission of pressure throug
the fluid contained within the bloodvessels i
all directions, in the immense force which the

* The power of the heart has also been cale
lated from the force supposed necessary to ra
the foot of one of the legs thrown across the
in the pulsatory movement which is then s¢
occur,—one of the most inaccurate methods #
could be adopted. figs

t See Part IV. of this article.

CIRCULATION.

blood occasionally appears to exert within an
aneurismal tumour; giving rise to its peculiarly
hard pulsation on every side, and assisting the
ravages by absorption which are frequently the
consequence of the larger internal aneurisms.
The pressure in an aneurism is obviously to be
measured by the extent of its internal surface
multiplied into the force with which the blood
moves in the part of the artery where it opens
into the aneurismal sac.
ec. Arterial pulse.—The arterial pulse, or suc-
cession of beats felt by the finger placed over
an artery, depends upon the impulse of the
left ventricle being communicated along the
arterial tube and the column of blood which
it contains.
When a ligature is put upon an artery, no
ulse is felt beyond the place where the artery
is obstructed, but it is distinct up to that place.
This experiment at once shews the dependence
of the pulse on the systole of the ventricle,
and establishes that this phenomenon is not
dependent on the progressive motion of the
blood, since, in that part of the artery placed on
the side of the ligature next to the heart in which
the pulse is distinct, the blood is at rest. Nor
does the pulse appear in ordinary circumstances
to depend upon lateral distension of the arteries,
for such distension occurs to so small a degree
as is quite insufficient to account for the produc-
tion of the pulse. Arthaud,* a French surgeon,
was the first who sustained, in opposition to
the opinion prevalent at the time he wrote,
the view that the arteries are not laterally di-
lated at each systole of the heart, and that the
pulse is not to be explained by such dilatation.
Arthaud shewed that when an artery is laid
bare, no perceptible enlargement of its calibre
takes place at the time when the heart con-
tracts and the pulse is felt. We have already
Stated that the arterial system being fuller of
blood at one time than another must be dilated
to admit the blood propelled into the aorta
from the ventricle; and it seems to follow
from the observations of Arthaud, which have
been ably confirmed by the interesting expe-
riments of the late Dr. Parry,t that the en-
largement of the capacity of the arteries is
effected principally by their elongation. Ac-
cording to these experimenters, when one of
the larger arteries is laid bare, the eye does not
distinguish any lateral enlargement corres-
‘soma to the systole of the ventricle, and
arry measured with great care the artery
at the time of each pulse and between the
beats without being able to detect the slightest
differences in its size; but though not percep-
tibly distended laterally, the artery undergoes
acertain change of place, for at each systole
of the ventricle it is propelled in a direction
outwards from the heart, and during the di-
astole it returns to its former situation. This
locomotion of the artery, as it is called, is

- Dissert. sur la Dilatation des Artéres,
1770.

+ Dr. C, H. Parry’s Inquiry into the Nature of
the Arterial Pulse. Bath and Lond. 1816. Dr.
Chas. Henry Parry’s Additional Experiments.
Lond. 1819.

Paris,

663
obviously produced by the distension and
elongation of the larger arteries near the heart.
A considerable elongation of the arteries may
also easily be seen at all sudden incurvations of
these vessels. The bend of the curved part is
generally increased and projected further out-
wards during the systole; and we observe that a
straight part of an artery, if fixed at its opposite
ends, is bent at the time of the pulse in conse-
quence of its elongation. In many persons in
a state of health the arteries may be seen to
move under the skin, although not exposed.
This motion is generally perceived at places
where there is a sudden bend of an artery, or
where the artery lies upon an unyielding part,
as bone, &c., and in some individuals an ap-
pearance of dilatation or lateral enlargement
even may be perceived in some of the larger
arteries. Although these circumstances shew
that the pulse is not attributable to a lateral
dilatation of arteries, yet it would appear that
such an enlargement does occur in a small
degree, for it is occasionally perceptible to the
eye in the arteries when laid bare; and M.
Poiseuille,* by means of a small apparatus,
capable of being applied round a part of an
artery, has proved distinctly the occurrence of
lateral enlargement, and estimated its extent
in the larger arteries at 1-11th of their dia-
meter.

The finger laid upon an exposed artery does
not feel any pulse, unless the artery be com-
pressed, and when the arteries are in their na-
tural situation covered by the integuments, it is
only when they lie upon a hard part, as a bone,
and when the sides of the artery are brought
nearer to one another by pressure, that the
pulse is perceptible. Those instances in which
this does not appear to be the case, as well as
those in which the dilatation occasionally seems
to occur below the integuments, may in like
manner depend upon the artery being subjected
to pressure of superjacent parts at the place ob-
served. It is also sufficiently obvious that the
pulse does not depend upon any active change of
the artery itself, or upon any vital contraction
and dilatation of the vessels, for the exact appear-
ance of the living pulse may be produced in the
arteries of a dead animal by injecting water
into the arteries with a syringe, if care be taken
to imitate with the strokes of the piston the
beats of the left ventricle of the heart. A fur-
ther proof of this, and an excellent illustration
of the nature of the pulse, is obtained from the
Curious experiment performed by Bichat of
connecting the bloodvessels of a living animal
with those of a dead one, the result of which is
the production of a pulse in the vessels of the
dead animal connected with the arteries of the
living one. In those instances in which a
communication has been established between
an artery and a contiguous vein in consequence
of a wound, or in what is called Aneurismal
Varix, the vein pulsates exactly like an artery.

Many have remarked that the pulse in the

* Sur la dilatation des Artéres; Magendie’s
Journ, vol. ix. p. 44; and Breschet’s Repert,
1828.

664

arteries of the extremities is a little later than
the beat of the heart on the ribs and the pulse
in the arteries in the immediate neighbourhood
of the heart. This retardation has of late been
more distinctly pointed out by Dr. M‘Donnell
of Belfast,* and by Weber of Leipsig.+ It is
much more marked in some persons than in
others, and is always most perceptible when
the circulation is slowest. With a little atten-
tion we can thus observe a distinct succession
in the occurrence of the beat of the apex of the
heart at the ribs, the pulse in the carotid,
facial, radial, and posterior tibial arteries, the
interval between each of which, though very
small, being yet appreciable by the finger.
Weber states that the retardation of the pulse
in the foot after that of the beat of the heart
amounts to not more than one-seventh part of
a second. We have ourselves confirmed by
experiments on several individuals the most of
these facts relating to the later pulse in the
more remote arteries. ‘The cause of the retar-
dation is obviously the elasticity and yielding
of the arterial parietes; for were the arteries
rigid tubes, it is manifest that the impulse of
the heart would be felt at one aid the same in-
stant of time throughout the whole of the
branches ; but as these vessels yield to disten-
sion, that part of them to which the distending
force is immediately applied is first dilated,
and this dilatation does not reach immediately
the remote parts.

The pulse has been correctly compared to
the propagation of an undulation or wave on
the surface of water; for the successive im-
pulses of the heart are first given to the column
of blood in the commencement of the aorta;
this column communicates these impulses to
the arterial parietes and tends to distend them.
The parietes re-act against this distending force
and compress the adjoining part of the column
of blood, from which the impulse passes to the
next part of the aorta; and so the pulse, gradu-
ally passing on from the trunks to the smaller
branches, becomes less and less perceptible as
the force of the heart is equalized by the elastic
resistance of the coats of these vessels.{

The pulse is still perceptible in very small
arteries: Haller§$ states that he was unable to
perceive any in small arteries of one-sixth of a
{ine in diameter,—an observation which does
not, however, prove the flow of the blood to be
uniform or without jerks even in vessels of
this size, for Spallanzani|| observed pulsations
in arteries of this small size; and the microsco-
pic observation of the circulation in transparent
parts by Haller himself, Spallanzani, and
others, shews that the visible impulse of the

* At the Meeting of the British Scient. Associat.
in Dublin.

+ De pulsu in omnib. arter. plane non synchro-
nico. Annot. Academ. Leipzig, 1834.

¢ Young’s Croonian Lecture on the Functions of
the Heart and Arteries, in,his Introduction to Me-
dical Literature.

§ Mém. sur le Mouvement du Sang. Laus. 1756.
Translated.

|| Expér. sur la Circulation, in French, by Tour-
des. Paris, An8. In English, by Hall. Lond.
1801.

CIRCULATION.

heart is communicated to the blood in the
smallest of those vessels, which have distinctly
the characters of arteries. . 1 Oa
The pulse being nothing else than the beats
of the heart transmitted through the arteries,
the consideration of the variations in force or
frequency to which it is subject belongs more
properly to the subject of the functions of the
heart. In this place we shall only mention
the mean of the usual number of pulsations of
the arteries in the space of a minute as they
occur at different periods of life.
Child before birth ......140—150
Newly-born infant .....130—140
Child one year old ......120
Two years. . Jo. 66. see vea tee
Three years’... .8 3. ese
Seven years .....eecee.. 85
Age of puberty. ..-..0+.. 80
Manhood) iis .5/). se WE MS
Old age... cs. 20s ses 60-—50
d. Vital properties of the arteries —In the
view we have hitherto taken of the arterial circu-
lation we have considered the coats of the arte-
ries as endowed with physical powers only, and
we have alluded to no other phenomena of the
motion of the blood than those which appear
to be connected with their elasticity. We have
now to direct our attention to the more strictly
vital and contractile powers of the arteries,
which constitute them an independent source
of force, and to examine how far the operation
of such powers may modify the flow of the
blood. We shall here discuss more in detail
the questions whether the heart is to be regard-
ed as the only source of the power by which
the blood is impelled, and the bloodvessels
merely as thé modifiers or regulators of the 4
force generated by the heart’s contraction—or
whether the arteries do not, by their own inde-
pendent power, contribute to the propulsion of —
the blood.
Physiologists are very much divided in their
opinions upon these questions, some regarding
the heart as the sole moving power, some suppo-
sing the bloodvessels to be the principal, the
heart a subordinate cause of motion; and others
adopting various modifications of these oppo-
site views. Many who agree in considermg
the heart’s action as insufficient to propel the
blood through the smaller bloodvessels into the
veins, differ as to the cause of the additional
power supposed necessary for the maintenance
of the circulation ; the larger and middle sized
arteries being looked upon by some as highly
contractile, and in consequence of this, the —
agents of propulsion ; the capillaries being re- —
garded by others as the most efficient promoters —
of the flow of the blood within the bloodves-
sels. We must, for the present, confine our
remarks to the first of these, or the opinion that —
the larger arteries are mainly or in part the
agents of the propulsion of the blood. an
That the arteries have the power of changing
to a certain extent, the quantity of blood whic
passes through them, and of thus modifying the
circulation by their own independent powers,
there can be no doubt, from the occu of
unequal distributions of blood, or of local

ee ee ee ee

=Lic

CIRCULATION.

terminations of that fluid which take place in
blushing, infammation, and other states of the
economy in which particular parts of the vas-
cular system become more or less filled with
blood than usual; for such variations in the
distribution of the blood would be impossible,
were an alteration in the powers of the heart
alone the only means of modifying the circula-
tion. The questions, however, whether such

wers as are possessed by the arteries contri-

te upon the whole to the progressive motion
of the blood or modify only its distribution,
are quite distinct from one another.

In its anatomical structure the fibrous coat
of the arteries differs considerably from muscu-
lar substance, and appears to resemble more
nearly the yellow elastic ligamentous tissue.
Its fibres are less mixed with cellular substance
than those of muscles ; they are also more dry,
hard, and friable, less coloured, and, accord-
ing to Hodgkin and Lister,* are destitute of
those transverse striz or lines observed by the
microscope in ordinary muscular fibres. The
chemical constitution of the middle coat of the
arteries differs also from that of muscle, for it
is less soluble in acetic acid, and more easily
so in mineral acids, and it is believed by Ber-
zelius and Young not to contain the animal
principle, fibrine, peculiar to muscular flesh.
Although we fully admit the importance of
these observations as establishing anatomical
and chemical distinctions between muscular
substance and the texture of the middle coat of
the arteries, they do not appear to us to warrant
the conclusion too hastily deduced from them
by some, that this coat cannot be irritable, or
does not possess any of the same properties as
muscle, the existence or non-existence of which
must be ascertained principally by physiologi-
cal evidence. For the transverse stria cannot
be considered as characteristic of all muscular
fibres; and were we to reason in this way
from the result of anatomical observations
only, we should be necessitated to deny the
irritability of various other textures, the con-
tractility of which from stimulation or without
it, is universally admitted, although anatomists
have not yet detected muscular fibres in them.

The coats of the smaller arteries are generally
believed to be proportionally thicker than those
of the larger trunks, and John Hunter held the
opinion that the yellow fibrous tissue exists in
greatest quantity in the larger arteries ; while
the smaller vessels, considered more active, are
composed of a substance more nearly allied to
muscular fibre. The grounds upon which the
latter opinion rests are upon the whole not very
satisfactory; and it appears to be opposed by
those instances in which, after the closure by
ligature of the principal artery of a limb, the
smaller collateral vessels which maintain the
circulation, after undergoing a rapid enlarge-
ment, assume the structure and general appear-
ance of the large arteries.

The irritability of the smaller arteries, now
very generally admitted by physiologists, though

* Appendix to the Transl. of Edwards’s Work
on the Influence of Physical Agents, &c. p, 443.
VOL. I.

665
it seems by some to have been inferred from
analogy, and to have been rendered probable
by Dr. Wilson Philip’s observations on the
effect of chemical stimuli in removing the
dilated state of the capillaries in inflammation,
was first distinctly proved experimentally by Dr.
Thomson of Edinburgh,* who caused the arte-
ries in the web of the frog’s foot to contract
powerfully by the application of mechanical
irritation as well as by chemical stimuli. His
experiments shewed that the nature of the con-
traction produced by stimulation of one of the
smaller arteries varies considerably, occupying
sometimes a greater or less space of the vessel,
and being at other times confined to one place,
sudden, and frequently so great as completely
to stop the passage of blood. They also de-
monstrated the fact that the contraction of the
small arteries does not follow immediately the
application of the stimulus, as occurs in the
voluntary muscles, but that a period of from
one to three minutes elapses before the contrac-
tion begins, and that the vessel remains con-
stricted for some time, and then returns to its
original state, unless inflammation shall have
occurred, in which case it dilates to a greater
size than natural. The irritability of the small
vessels has been fully established by experi-
ments similar to those of Dr. Thomson, by Dr.
Wilson Philip,t Dr, Hastings,{ Kaltenbrun-
ner,§ and Wedemeyer,§ the last of whom suc-
ceeded in causing the small arteries to contract
by means of galvanic as well as of mechanical
irritation. The constriction which follows the
injection of styptic and irritating fluids into the
arteries, observed by Hales|| in animals recently
dead, and similar experiments by Wedemeyer,
may be adduced as another proof of their irrita-
bility. The stoppage of hemorrhage from cuts
of the small arteries and capillaries, assisted as
it is by cold or irritating applications, may be
regarded as the effect of the same property.

Contractions do not occur so readily or ob-
viously in the large as in the very small arte-
ries. Verschuir appears to have been the first
who observed, in a manner not liable to fallacy,
distinct contractions of the larger arteries to
occur after the direct application of a stimulus.
From an extended series of experiments upon
this subject, described in his Inaugural Disser-
tation De Vi Arteriarum Contractili, Verschuir
was led to adopt the opinion that the arteries
are possessed of irritability, or contract in the
same manner as muscles do from irritation; as
he observed very obvious and powerful con-
tractions to occur when, by means of a sharp
point or chemical stimuli, he irritated the coats
of the larger arteries of animals.

Haller, though considering the middle coat

* Lect. on Inflammation. Edin. 1813.

+ Introduct. to the second part of his work on
Fever. ,

{ Introduct. to his work on the Inflammation of
the Mucous Membrane, &c, :

§ Exper. circa statum Sang. et Vasor. ia Inflam-
matione. Munich, 1826.

|| Untersuch. tiber den Kreislauf des Blutes, &e.
Hannover, 1828. See also Koch in Meckel’s Archiv.
1832, p. 121.

4] Statical Essays, ii, p. 124. :

‘ x

,

666

of the arteries as of a muscular nature, was un-
successful in producing obvious contractions in
them. The repetition of the experiments of
Verschuir by many others has been attended
with very various results ; some confirming his
observations, others having entirely failed in
peg any obvious contraction, or not being

isposed to consider it of a muscular kind.
Among the last may be mentioned Nysten,
Bichat, Wedemeyer, and J. Miiller.

It must be obvious that, laying aside the
difference of opinion regarding the nature of
the contractions when they are admitted to
occur, in a question of this kind a positive re-
sult deserves more consideration than a nega-
tive one, provided the phenomena stated to
have been observed are such as to be appre-
ciable by all. Among the experiments favour-
able to the view that the large arteries are en-
dowed with irritability, may be mentioned those
described by Hastings,* and a series of unpub-
lished observations by Dr. Thomson, to which
we have access, which seem to prove in a very
satisfactory manner the frequent occurrence of
«contractions in the larger arteries after stimula-
tion; and to point out as a cause of the failure
of some at least of the previous experiments,
the long time which commonly elapses between
the application of the stimulus and the occur-
rence of the contraction ; together with the cir-
cumstances formerly remarked by Verschuir,
that the contraction is not an invariable conse-
quence of the stimulation, and that it occurs
much more readily in some animals than in
others.

According to Dr. Thomson the contraction
of the larger arteries is in general not percepti-
ble before from three to ten minutes after the
application of the stimulus. When galvanism
is used, the shocks need not be strong, but
must be frequently repeated in order to induce
eontraction.

Many have remarked the gradual or sudden
contraction of the trunks of arteries which have
been laid bare in Man as well as in the lower
animals. When exposed, an artery is some-
times equally contracted for some length along
its tube ; at other times its surface assumes a
waved appearance from the occurrence of irre-
gular contractions or alternate contractions and
dilatations, and not unfrequently the coat of
the artery is much constricted at one point
only, as if a tight cord had been passed round
it. Appearances of this kind, which seem to
indicate very distinctly the possession of the
property of irritability by the arteries, are well
known to many surgeons ; they were noted by
Drs. Jones and Thomson, in the experiments
upon which Dr. Jones’s work on Hemorrhage
was founded; and also by Dr. Parry, who
nevertheless refuses to consider them as wuri-
table contractions. At p. 74 of his work

on the Powers of the Arteries, Dr. Parry,

referring to Experiment 13th, says, “ thus a
very narrow ring of the carotid became, while
it was under examination, contracted as if a

* Inang. Dissertat. Edin. 1817, et loc. cit. See
also Hunter on the Muscularity of the Arteries,
Edin. Med. and Sarg. Journ, xxii. p. 256.

CIRCULATION.

small ligature had been half tightened around
it.” So also in Experiment 24th, he relates
that a = of the carotid artery of a ewe was
diminished by a third of its original diameter
under exposure, after having been half an hour
denuded, while the neighbouring parts had be-
come rather dilated, and that while he was pro-
ceeding to measure one of these dilated por-
tions, he “ saw it shrink to nearly the same
size as the constricted part.” It appears to us

manifest, that, whether these irregular diminu-

tions of the diameter of the artery, obviously

occasioned by a shortening of its fibres, are at-

tributed to the exposure of the artery to the air,

or the violence done during the dissection of it

by the scalpel, they must equally be regarded

as the consequence of stimulation of one kind

or other, and are therefore of the nature of mus-
cular contractions.

Hoffmann first noticed the contractions of
the arteries from the application of acrid che-
mical stimuli to their. coats; and it appears
from numerous subsequent experiments, that
contractions are more readily induced in this
than in any other way. Were there no other
proofs of the contractility of the arteries than
those derived from the effect of chemical
agents, we should not feel inclined to place
much reliance on them, on account of the pos-
sibility of there having been induced a perma-
nent alteration of the texture from chemical
action; but the results of such experiments
form an important confirmation of those which
are performed with mechanical and galvanic
irritation. We cannot, however, acquiesce in
the opinion of Wedemeyer* and others who
compare the distinct and well-marked contrac-
tions of particular parts of the arterial tubes,
such as those above alluded to, to the general
constriction of other textures, and more parti-
cularly to the shrinking of the skin which
occurs from the influence of cold, passions of
the mind, &c.

I’rom these considerations we are induced to
adopt the opinion that the contractions which
under certain circumstances occur in the ar-
teries resemble muscular contractions more
nearly than any other vital phenomenon. The
positive evidence of direct experiment obviously
proves that the contractions in general follow
the application of some stimulus to the artery ;
but these contractions differ from that of mus-
cular parts chiefly in the length of time which
elapses after the application of the stimulus
before the change of size begins, in the slow-
ness with which the contraction is succeeded
by relaxation, and in the want of obvious cor- —
respondence between the force of the stimulus —
and the extent of contractions which follow it. —

Besides the more marked contractions of
parts of their tubes, the arteries are subject in
various circumstances to undergo a slow au
gradual diminution of their diameter through
out their whole length, which is considered |
many physiologists to indicate the possessia
by them of a property of the nature of contrai
tility different from irritability in its

:
;
}
:
}
;
;
|

* Locicit.

CIRCULATION.

mena and the causes which call it into action.
A power of a similar kind, to which the name
of Tonicity is applied, is believed to reside in
the voluntary muscles.*

The experiments and observations generally
stated in proof of the tonic power of arteries
are the following :—

1. When a ligature is placed upon an artery
of a living animal, the part of the artery beyond
the ligature becomes gradually smaller, and is
emptied to a certain degree, if not completely,
of the blood it contained.

2. When a part of an artery in a living ani-
mal is isolated from other organs by means of
two ligatures and punctured, the blood issues
from the orifice, and the enclosed portion of
artery is nearly completely emptied of its con-
tents.

3. The empty condition of the arteries gene-
rally found after death is believed to be, in

at least, produced by a slow contraction
of the whole of the large arterial tubes; for it
has been observed, that some hours after death
the arteries are much diminished in size, and
this occasionally to such an extent as to be
rendered impervious, as was observed in the
umbilical arteries of the navel string by John
Hunter+ and others.

4. It has been shewn by Poiseuille{ that
when a portion of an artery from an animal
recently dead, and one from an animal that
has been dead for some days, are distended
with an equal force, the portion of the artery
from the recently dead animal becomes more
contracted after the distending force is removed
than the other one.

5. In the last place, when a large artery is
divided, the cut extremities frequently become
so completely constricted as wholly to prevent
the issue of blood, and this kind of contrac-
tion is well known to occur in a greater degree
after laceration of an artery than after division
by the knife: hence the less danger to be ap-
prehended from hemorrhage in lacerated than
im incised wounds; and thence the possibility
of producing the closure of one of the larger
arteries by the mere compression or torsion of
_ its cut end.

In the three last-mentioned proofs of to-
nicity the contraction of the artery followed
the application of some kind of irritation ; for
the exposed artery was dissected out by the
scalpel, and ligatures were tightened round it,
the coats of the artery were stimulated by dis-
tension in Poiseuille’s experiment, and in the
twisting or torsion as well as in the division of
an artery by laceration or cutting there is always
an irritation applied to the contracting part.
The tonicity or tonic contractility therefore was
in some of these instances first called into ope-
ration and in others increased by irritation, and
Ought not therefore to be distinguished from
irritability as regards its cause, but only as
relates to its phenomena.

The evacuation of the blood from arteries

* Parry, loc. citat.
_ + On the Blood and on Inflammation.
_ ¢ Magendie’s Journ. vol, viii.

667

beyond the place at which they have been tied
in the living body, and the contraction of ar-
teries which takes place in the dead body, as
well as the rigidity of muscles soon after death,
or their retraction when divided in the living
body, all seem to indicate a tendency in ir-
ritable parts to undergo a slow and continued
contraction during the persistance of their vital
powers. This tendency to contraction seems
to differ from the shortening and subsequent
relaxation which are the more or less imme-
diate effects of stimulation in truly irritable
parts, and it seems to be more dependent upon
the removal of the forces by which the parts in
which it occurs are kept in a state of distension
than upon any other cause.

It is obviously in consequence of this ten-
dency to contract when not distended by a
force from within, that the arteries are always
nearly accommodated to the quantity of blood
contained in them. But while we are con-
strained to admit the existence of the peculiar
slow contractile power in arteries appropri-
ately denominated tonicity, we would caution
the accurate physiologist against considering
as the effect of this property rather than of irri-
tability any of those contractions of the arterial
tubes which are induced or increased by me-
chanical, galvanic, or other stimuli.

e. Influence of the vital powers of the arte-
ries on the circulation.—Let us now inquire in
what manner the flow of the blood is influ-
enced by the irritability and tonicity of the
arteries.

Some of those who have regarded the arteries
as contributing by their active powers to propel
the blood have conceived it sufficient for them
to prove that there is a necessity for some
additional force in the circulation besides that
of the heart, in consequence of the total ex-
penditure of the heart’s force from the windings
of the small vessels, the friction of the blood
against the side, and other resistances to be
overcome in the capillary system. This expen-
diture of the heart’s power admitted by many
on insufficient grounds has been very generally
overrated. Although the causes just men-
tioned may diminish to a certain extent the
propelling power of the heart, there are various
very simple experiments which shew that the
heart’s action is propagated with a propelling
effect through the whole vascular system, so as
to act in the extreme vessels and veins.

In the first place, Haller, Spallanzani,
Thomson, and many others have observed in
the transparent parts of animals that the im-
pulse of the heart is transmitted to the very
ends of the small arteries, which may be less
than ;4,th part of an inch in diameter, and that
in some states of the circulation the impulse of
the heart is continued on through the capillary
vessels and into the commencements of the
veins. The fact that this generally occurs when
the action of the heart is weakened, and when
the vessels are consequently not sufficiently
distended by its impulse to react by their
elasticity and convert the remitting into a
uniform force, is a distinct proof that in the
natural state of the circulation a greater pro-

2x 2

668

portion of the force of the heart must be trans-
mitted through the blood to the capillaries,
and must act through them upon the column
of blood returning in the veins.

From the same experiments it has appeared
that in general the instant any obstruction pre-
vents the action of the heart from being pro-
pagated onwards in the arteries, the progressive
current of the blood in the small vessels be-
comes slower and soon ceases, any motion
which goes on afterwards being quite of a dif-
ferent kind from that occurring in the natural
circulation.

An experiment performed by M. Magendie,
and formerly referred to, also affords a very
satisfactory proof that the heart’s force acts in
propelling the blood through the whole vascular
system. M. Magendie dissected the femoral
artery and vein separate from the neighbouring
parts, and passing a ligature under them tight-
ened it round the whole limb, excepting the
two principal bloodvessels, through which the
blood was allowed to flow freely. He was thus
enabled to shew that the flow of blood from an
orifice in the vein was immediately dependent
on the force of the heart acting through the
artery, as it was suddenly diminished and soon
completely ceased the instant that the latter
vessel was obstructed, and became more or less
rapid according as it was more or less com-
pressed. We would further remark that the
experiments of Hales and Poiseuille, more par-
ticularly the latter, have shewn that there is
little if any difference in the force of the blood
in arteries of very different size.

On the other hand, it appears to us suffi-
ciently clear that the occurrence of any general
contraction of the coats of the arteries would
have the effect of opposing an obstacle to rather
than of assisting the progress of the blood in
the arteries, just in proportion to the degree of
the force of the heart, which would necessarily
be expended in dilating them to the required
size, im order to allow of the free transmission
of the blood by them; and as, according to the
commonly received opinion, the contractile
powers are greater in the smaller than in the
larger arteries, the operation of this contraction
would be much the same as the diminution of
the aperture through which blood flows from
an inorganic tube, and would thus cause a
still greater obstruction to the flow of blood
than a general contraction. It is only on the
supposition that the arteries undergo an undu-
latory or vermicular contraction, proceeding
from the larger to the smaller branches, that
this contractile force can be believed to con-
tribute to the progressive motion of the blood,
because then it might be conceived to assist
the elasticity of the arterial parietes in propa-
gating the force of the heart along the column
of contained blood, and even augment this
force by an additional power. But we would
remark that no such vermicular action has
been ascertained to occur by any observations
or experiments with which we are acquainted ;
that in artificial injection of fluids into the
Jarge arteries of dead animals a force of a few
pounds. is found to be sufficient to propel these

CIRCULATION.

fluids, when not of an irritating kind, from the
arteries into the veins; and that it follows from
the direct experiments of many, more particu-
larly those of I Hales, Poiseuille, and Magendie,
that the action of the heart, transmitted by the
elastic arteries, is the only cause operating in
the progressive propulsion of the blood in |
arteries of such a size as to admit of the force
of the blood being measured in them. ,
In asserting, however, that a general con-
traction of this kind, if it occurred in the vas-
cular system, would upon the whole obstruct or
retard rather than assist the progressive motion
of the blood in the arteries, we would not be
supposed to deny that the vital powers of the
arteries may modify very considerably the dis-
tribution of blood to different parts, for it is
manifest that an increased action occurring in
one part of an artery may hinder the blood
from being transmitted in its usual quantity
into a neighbouring part, while a dilated state
of an artery or its branches, or, if we please to
call it so, a diminished action or greater weak-
ness of resistance of the coats of the artery
considered relatively to the powers of propul-
sion operating through it, may occasion the .
flow of a greater quantity of blood to a part, |
as occurs in local inflammations. Among the
many indirect arguments adduced on hoth sides
of this question may be mentioned the follow-
ing. In the first place, the fact that in the
lowest classes of animals, as in Vermes and
Insects, which have no proper heart, the blood-
vessels propel the blood by their contractile
power, and that in some of the higher animals,
particularly Reptiles and Fishes, parts of the
vascular system, as the bulb of the aorta, a
considerable portion of this vessel, parts of the
veins, and so on, are distinctly contractile, and
assist the powers of the heart, are adduced as
proofs from analogy that the arteries in warm-
blooded animals may have the same power and
perform the same function. Now it may be
answered to this, that the circumstance of the
lowest classes of animals having no proper
heart is the final cause of or an obvious reason
for the greater contractility of these vessels ;
and in the second place, that no rythmic con-
traction is observed to occur in the arteries of
warm-blooded animals of the same nature as
that observed by Haller, Spallanzani, M. Hall,
and others in the bulb of the aorta and other
parts of the vascular system of cold-blooded
Vertebrata. For similar reasons we are not
inclined to attach much importance to the ar-
gument in favour of the independent powers of —
the arteries deduced from the alleged occur-
rence of circulation in acephalous fetuses, in”
all of which the proper muscular heart seems
to be wanting; for although the distribution «
the vessels in these foetuses has been suf
ciently accurately determined, the nature -
the circulation which occurs in them is a sul
ject involved in the greatest obscurity. Th
seems good reason to doubt that such foetus
have ever existed alone in the uterus, in whic
case their vessels may, as is known in ma
them to have occurred, have been connec
with those of a perfect fetus; and even:

ee a a So. oe

eo

—— Ve Oe

fi

CIRCULATION. 669

this not the case, the absence of the heart might
be attended in these malformed productions
with an unusual development of muscular
power.in parts of the vascular system.*

In conclusion, we may remark that the argu-
ment drawn from the occurrence of circula-
tion apparently little impaired through arteries
which have been completely ossified for a con-
siderable time, seems to be very much in favour
of the view we have taken that the heart alone
is the cause of the progressive flow of blood
through the arterial tubes.

3. Phenomena of the capillary circulation —

The phenomena of the passage of the blood

from the terminations of the arteries into the
commencement of the veins through the capil-
lary vessels, are highly interesting and mapetr
tant in many points of view, for the immediate
respiratory change which the venous blood
undergoes in the pulmonary vessels, and all
those alterations of composition which accom-
pany nutrition, growth, secretion, and other
organic processes connected with the systemic
vessels, occur in the smallest ramifications of
the pulmonic and systemic circulation, and the
morbid state of inflammation as well as the
various pathological changes which occur as its
consequences are intimately connected with an
al condition of the capillary system.

a. Structure and distribution of the capillary
vessels—The name of capillary is generally

given to all those minute vessels which form

€ means of communication between the
small ramifications of the arteries and veins;
but there is some difference in the opinion of
anatomists and physiologists as to how much
of the vascular system ought to be included

under the division of the capillary vessels.

Some, adhering to the strict meaning of the
term, apply it to all the small vessels whatso-
ever under a certain size; others hold that
between the extremities of the arteries and
veins there is always situated a series of minute
tubes of nearly equal size in their whole length,
and not ramifying like the arteries or veins,
which constitute a system of vessels distinct

from the others in their structure, distribution,

and properties, to which the name of capillary
ought to be restricted.t The last view appears
to us to be founded in a partial acquaintance
with the system of minute vessels, for though
it may be true that in some parts of animals
the capillaries have obviously the structure
above described, and seem to form a system of
vessels apart from the smaller arteries and
veins, yet this is by no means the case in other
textures ; and we think that the more extensive
observation of the structure of these vessels in
various parts will shew that in the greater
Dumber, as is well ascertained to exist in
many, the smaller arteries pass into veins
quite in a gradual manner, the ramifications
of each class of vessel becoming more and

* See the Researches of Elben, Tiedemann,
Breschet, and others on Acephalous Monsters.

+ Dr. Marshall Hall’s Essay on the Circulation
of the Blood, Lond. 1831. Dr. James Black’s
cant Inquiry into the Capillary Circulation, Lond.

more minute until they meet, the two kinds
of vessel presenting no difference of character
other than the change of direction assumed
by the moving blood, which enables us to
say with certainty where the artery termi-
nates, and at what point the vein begins,
and affording thus no reason to consider the
continuous tube by which they join as different
in structure from either the minute artery or
vein. While we acknowledge therefore the
importance of the observations which point
out the existence of capillary vessels of a uni-
form size in some textures, we think it necessary
to retain the name of capillary as applied to all
the minute vessels, both for the reason that the
communicating vessels are not every where of
the same kind, and that from the use already
made of the term by physiological writers its
meaning will thus be more easily understood.
The vessels which lead from arteries to veins
are of very various sizes, some admitting only
one globule at once, others being so large as to
allow of the passage of three, four, or even a
greater number of red globules together. In
tracing with the microscope the motion of the
minute streams of blood as they pass through
the capillary vessels, the eye is guided by the

Fig. 330.

670

motions of the red globules principally, for it
is very rarely indeed that the current of fluid
which carries the globules along can be recog-
nized in the ordinary modes of observation.
The capillary circulation is most easily seen
in cold-blooded and in young animals, both
on account of the large size of the red glo-
bules and the small number of the vessels.
Since the first discovery of the capillary circu-
lation by Malpighi, the transparent web be-
tween the toes of the hind feet of the frog has
been universally adopted as the most con-
venient situation for observing this beautiful
spectacle with transmitted light. The fins and
tail of fishes, the tail of the larva of the Frog
and Newt, the external gills of the same ani-
mals as well as of cartilaginous fishes, the
mesentery of the Frog or of small warm-
blooded animals, the wing of the Bat, the
lungs and urinary bladder of Reptiles, the
liver of the Frog and Newt, the membranes
of the incubated egg, the yolk of the Skate’s
egg, are all situations favourable for the ob-
servation of the capillary circulation. The
capillary circulation has been viewed in only
a small number of warm-blooded animals, and
.in very few of their textures; but the minute
injection with coloured fluids of all parts of
the bodies of Quadrupeds and of Man leaves
little doubt that in them also, whatever vari-
eties there may be in the size, number, and
distribution of the small vessels, the blood
passes in every organ from the small arteries
into the returning veins by minute continuous
tubes of the same nature as those more easily
observed in the situations above-mentioned.
Some are inclined to consider the minutest
or proper capillary vessels as destitute of vas-
cular parietes, and consisting of mere passages
through the texture of the organ in which they
exist without any lining membrane. This
opinion is founded on the impossibility of
seeing the coats of the vessels, the rapidity
with which new capillaries may be developed,
and some other circumstances. The extreme
degree of minuteness of the smallest capil-
lary vessels must render futile any attempts
to decide this question by direct observa-
tion. Besides the general analogy between
the larger and smaller vessels, there are
several circumstances known which seem to be
strongly in favour of the view that the capil-
laries do not differ in this respect from other
vessels. 1st, It is allowable to suppose that
the active properties of the capillary vessels
belong to parieties as in the larger vessels.
2d, In many transparent parts of animals in
which the terminal arteries and veins do not
diminish to a very small size, the coats of the
vessel may be seen with the microscope, as in
the external gills of the Amphibia, and in the
vascular rete of the ear of birds and reptiles,
in which tie capillary vessels may, after
having been injected, be separated from the
neighbouring soft texture. 3d, The conver-
sion of small into larger vessels with visible
coats in those instances in which the course
of blood through the vessels of a part has un-
dergone an alteration, is in favour of the pre-

CIRCULATION.

‘view. The argument in favour of the non-

vious existence of parietes in the smaller
vessels. And 4th, The constant and regular
distribution of the minutest vessels in many
parts of animals appears to support the same

existence of capillary parietes deduced from
the alleged facility with which the blood occa-_
sionally passes out of the regular vessels and
takes an irregular and indeterminate course
through the non-vascular parenchyma of an
organ, we believe to be founded, in some in-
stances, in peculiarities belonging to a few parts
only, and in others in inaccurate observation ; ;
for in almost all those situations in which the ;
capillary circulation may be seen with ease p
.
I

and distinctness, the constancy of the minute
passages which the blood permeates is un-
doubted.

From the more accurate means of making
minute anatomical researches that have been
introduced in modern times, the existence of |
serous, exhalent, and white vessels has become
a matter of great doubt, for vessels of this
description which do not admit the red glo-
bules and liquor sanguinis together cannot be
made obvious to the senses by the most de-
licate injections or dissections; and the ob-
servation of the capillary circulation in the
transparent parts of animals affords the most
convincing proof that the smaller arteries
have no visible terminations excepting in the
capillaries and small veins. In observing |
attentively the web of the frog’s foot and other

Fig. 331.
, © :
2 0,
Sz oN i332 ;
S
SS hy Y
Se
Ss Sy ry
+ ij 4
iy
ar (% St ;
9 )
Sy a
oe 4 a ) Q ;
5) a >. DSO .
A ras \" 0.
oye A
G j "a
: i S Cm :
Ay g AY : By ; \ , ‘ y
( ZF 5 5 ;
Ag
We Y 2 e " ~ ‘*
- " —- ..
SS
. ed ~<a

al

Capillaries in the web of the Frog’s foot magnified.
é

transparent parts in which the motion of the —
blood is easily seen, we occasionally see glo- —
bules of blood run into passages of the tissue
which we did not perceive before ; but a suf-—
ficient acquaintance with the structure and dis-
tribution of the smallest of the capillaries m
these situations will soon convince the carefu
observer that the vessels into which the bloo
was seen to pass, apparently for the first time,
existed fully formed before, that the fluid part
of the blood passed in part through them, and
that the stoppage of the red particles was to

CIRCULATION. 671

a great measure dependent on partial or local
impediments. The compression of one of the
small arteries, for instance, will frequently,
after causing oscillation of the globules of the
blood in the smallest capillaries, be followed
by the disappearance of some of them; but
im a very short time, or when the obstruction
is removed, the blood regains its former velo-
city and force, and flows into exactly the same
passages as before.

The notion that the smaller vessels are con-
tinuous with the smaller lymphatics, and more
especially with the excretory ducts of glands,
seems to be fully disproved by the accurate
researches of Malpighi, Mascagni, Panizza,
Miiller, and Weber, which have shewn that
the lymphatic vessels originate at all parts of
the body by a plexus of tubes every where
closed, and that the excretory ducts of secre-
tory organs begin always by shut ends.

We believe it to be satisfactorily shewn that
in the whitest of the textures (with the excep-
tion perhaps of the cornea and crystalline lens),
there is no necessity for the supposition of
vessels admitting the fluid parts only of the
blood, or of serous vessels, as they have been
termed; and that in all of them there exist
small bloodvessels which admit very fine rows
of globules in their accustomed proportion to
the fluid part of the blood: for many textures
which appear perfectly white or colourless, or
only slightly yellow when viewed with the
naked eye, are found, when examined with the
microscope, to have small vessels carrying blood
globules through them. Spallanzani and others
shewed that very small vessels taken singly or
seen in very thin layers have almost no per-
ceptible colour; and it is a well known fact
that, in what are called the red textures, the
colour (as of muscle for instance) is not ex-
clusively dependent upon the quantity of red
blood in them. It is difficult, indeed, to con-
ceive how the circulation of the blood could
be carried on at all, or how the red particles
of the blood could ever be returned to the
heart were the globules to be retained in the
larger vessels, and all the white textures to
admit only the fluid parts of the blood.

In adopting the opinion that the arteries
terminate always by direct continuity of tube
in the veins, and that no other visible passages
are connected with the minute vessels, we
must suppose. that the various interchanges of
materials occurring between the blood and the
organized textures or foreign matters, as in nu-
trition, secretion, respiration, transpiration, &c.
must take place by some process of organic
transudation through invisible apertures of the
minute vessels.

b. Properties of the capillary vessels and in-
Sluence on the circulation—¥rom the expe-
riments already referred to, it is apparent that
the smaller arteries, so long as they can be
distinguished from other vessels, are capable
of being excited to contraction by the appli-
cation of a stimulus; but we have no means
of shewing this with regard to the minutest
capillary vessels, because we can scarcely apply
any stimulation to them without affectin some

of the smaller arteries at the same time. When
it is said, for example, that the capillary ves-
sels are irritable, because the application of
ammonia or spirits of wine causes them to
become smaller, it is difficult to determine
how far this appearance of diminished size in
the capillaries depends on their receiving less
blood, in consequence of the contraction of the
small arteries leading to them or upon the less
size of these vessels themselves. In the expe-
riments of Dr. Thomson and others, however,
the application of salt and other stimuli ex-
citing inflammation have appeared to dilate
even the smallest capillary vessels, and such
a dilatation can scarcely be considered as in-
dicating any thing else than a less power of
resistance in these vessels ; and when the ap-
plication of ammonia or spirit of wine restores
such dilated capillaries to their natural con-
dition, we do not see that any other natural
inference can be drawn from this fact than that
the capillaries have been contracted by the
influence of these stimuli; for the contraction
of the small arteries alone, although it might
restore the lost velocity of the blood, would not
diminish the capillaries to their former size.
This general diminution of size ought how-
ever to be carefully distinguished from the
more marked and local contractions of true
arteries.

The velocity of the blood is quite uniform
in the capillaries of the adult animal in the
natural condition of the circulation. There is
reason to believe the capillary vessels to be
highly elastic, and to have the effect of com-
pleting the change which is begun by the
arteries, viz. that of equalizing the force of the
heart transmitted through the blood. We do
not, in observing attentively the capillary
vessels, ever perceive any motions of alter-
nate dilatation and contraction of their sides.
The blood flows through them as through
small glass tubes; and if they act by other
powers than by their elasticity alone, this
action must be of so slow a kind as not to be
perceptible. There can be no doubt that any
action of contraction occurring in the capillary
vessels, whether alternating with dilatation or
not, could have no effect excepting that of ob-
structing the passage of blood through them.
It would act upon the contents of the arterial
system much in the same way as the dimi-
nution of the aperture at the end of a rigid
tube would affect the flow of fluid through
it, that is, either a less quantity of blood would
pass through the capillary vessels in conse-
quence of their less size, or a greater portion
of the heart’s force would be expended in di-
lating these vessels to a sufficient extent.

The principal reasons which we feel inclined
to adduce for believing that the heart's action
is continued onwards through the capillaries,
and is sufficient to return the blood through
the veins back as far as the heart itself, are the
following :—1. That in an animal recently
killed a very small force only is requisite to
cause bland fluids to follow the course of the
blood, provided the injection be made before
the tonic contraction has had time.to constrict

672

the vessels. 2. The experiments of Hales and
Wedemeyer shewing that, according to the
more or less stimulating character of the fluids,
their passage through the vessels was more or
less easy. 3. The experiments shewing that,
in an animal which has been dead for some
time, steeping of the body in warm water, and
the injection of warm water into the vessels,
so as to clear the passage through them, puts
the vessels in such a condition that a force of a
few pounds is sufficient to effect the pro-
pulsion of fluids through them. 4. The ob-
servations of Haller, Spallanzani, Magendie,
and others, that all regular progressive motion
of blood in a vein, or the issue of blood from
an orifice in a vein, ceases very soon after
the heart’s action is suspended, or when any
obstacle prevents its force being communicated
to the blood in the veins. 5. The observations
of Spallanzani, Thomson, and others, that the
impulses of the heart are visibly continued on
through the small arteries and capillaries, and
even into the veins in some states of the circu-
lation. This phenomenon is most apparent at
the time when the action of the heart is weak,
and in such states of the circulation this re-
mittent flow of the blood may be converted
into a merely oscillatory movement without
any regular progression by the gradual increase
of the pressure applied to the artery which
supplies the blood to the capillary vessels
under observation; a fact which shews dis-
tinctly on the one hand that the force of the
heart is continued on through the capillaries,
and on the other that when a resistance 13 op-
posed to the progress of the action of the
heart through the arteries, no other force then
operates sufficient to cause a continued and
progressive motion of the blood.

But, although the small vessels do not con-
tribute by their active contraction to propel the
blood through them, or although they do not
as a whole assist the force of the heart, it is
yet very apparent that they have the power of
modifying in a remarkable manner the flow of
blood in particular parts. Among the circum-
stances which prove this power of the small
vessels to modify the circulatiun may be men-
tioned the various instances in which there
occur local determinations to particular parts,
unaccompanied by any change in the action of
the heart or in the general circulation. 1. The
act of blushing and erection, or the reverse
actions of paleness, collapse, &c. which seem
to depend, in most instances at least, on some
change in the terminal vessels 2. Inflam-
mations or hemorrhages confined to a parti-
cular part of the body. 3. The increase or
decrease of secretions from glands, periodical
or instantaneous. 4. The increased size of
the vessels of the uterus during pregnancy,
of the mamme after child-birth, &c. 5. The
enlargement of bloodvessels in new growths,
tumours, &c. 6. The enlargement of collateral
anastomosing vessels, after the closure of the
principal trunk ofa limb. And, 7. The unequal
growth or development of different parts of the
fetus. Although we do not understand the
nature of the change in the vessels which

CIRCULATION.

accompanies these partial rience 4
blood enero parts, they all suffi-
ciently demonstrate that while the heart’saction
remains the same, the quantity of blood sent to
particular parts must have been modified by
some action of the vessels themselves.

There are some physiologists, however, who
hold the opinion that the motion of the blood
is promoted in some way or other (they do not
sufficiently clearly explain how) by powers
acting on it during its passage through the
capillary vessels; ‘and there are a few who
have gone so far as to suppose that the
heart drives the blood only as far as the capil-
laries, from whence it is propelled onwards
into the veins by powers originating im the
small vessels themselves. These opinions have
been supported chiefly by arguments drawn
from the facts already mentioned as illustrating
the power of the small vessels to modify the
circulation or to cause local variations in the
distribution of the blood, as also on the fol-
lowing grounds, which are ably stated in a
supplement to his Outlines of Physiology,*
recently published by Professor Alison, of
Edinburgh, who is one of those who have
more lately adopted this opinion, and by Dr.
Black in an ingenious essay on the capillary
circulation.+

Besides the analogical argument drawn from
the lower animals having a circulation of fluids
without any heart, and the supposed unaided
Sears in acardiac foetuses, it is stated
that—

1. After the heart of the frog or such cold-
blooded animals has been cut out, or a liga-
ture passed round the aorta, some motion of
the blood still continues to occur for a few
minutes in the small vessels ; and it is farther
stated, that this motion is influenced by heat,
by certain applications to the web of the frog’s
foot, and the state of the nervous system.}

2. That while the circulation is going on
with its usual freedom, the direction and velo-
city of the flow of blood are subject to sud-
den or rapid changes which do not admit of
being accounted for simply by contractions of
the vessels.

3. That the blood when out of the vessels,
immediately after it has been drawn, or when
extravasated in the textures, performs motions
which seem to belong to itself or are spon-
taneous.§

4. That the passage of the blood through
the capillary vessels of the lungs is imme-
diately influenced by the chemical change of
the venous blood into arterial, for its velocity
is diminished as soon as this change does not
occur.|| a

5. That the remoteness of the capillaries of
the vena porte of the liver from the heart ren-—

* Outlines of Physiology, Supplement to 2d
slits: Maite. Iie? yap oe 2
+ London, 1825. i
¢ Haller, Guillot, Leuret and Wilson Philip,
Marshall Hall, and others. ;
§ Kielmeyer, Treviranus,
(Esterreicher, and Schultz.
|| Dr. Alison, loc. cit.

Carus, Czernm

CIRCULATION.

ders probable the existence in them of some
power capable of propelling the blood inde-
pendently of the heart’s action.

6. That in the production of new vessels
which occurs in adhesion or granulation, the
new blood executes oscillatory motions in the
rudimentary vessels while in the act of form-
ing, before these parts of vesse!s are connected
with the previously existing branches through
which the heart propels the blood ; and this is
said also to occur in the formation of new ves-
sels in natural growth.* .

7. That in the formation of the vascular
area of the incubated egg the blood moves in
part through the veins and small vessels before
it is impelled by the action of the heart.t+

We would remark, regarding the oscillatory
and irregular motions described by Haller and
others as occurring in the small vessels of the
web after removal of the heart or ligature of
the aorta, that we believe some of these to be
caused by the elasticity of both the arteries
and veins, and others to be occasioned by the
gradual or tonic contractions which take place
in the arteries after death :{ they occurred in all
Haller’s observations, but in Spallanzani’s only
when the apparatus of hooks constantly em-

loyed by Haller was applied; and so far as we

ave ourselves been able to observe them, we
havealways found them influenced by very slight
changes. When one of the small vessels is
obstructed they cease altogether, which ought
not to be the case were they dependent upon
powers belonging to the capillaries or the blood
in them. Some varieties in the velocity and di-
rection of the blood in the smaller vessels we
have reason, from our own observations, to
attribute to the same causes, and we think it
consonant with such a supposition that heat or
other agents influencing the contraction of
arteries should influence these irregular mo-
tions. The oscillations of blood in parts of
vessels which are in the process of formation
in adhesions and granulations, or in natural
growth, we have not yet been able to observe so
clearly as to be certain that we were not de-
ceived; but, even supposing them to have
been satisfactorily proved to occur, we should
be inclined to doubt the possibility of ascer-
taining with accuracy that these portions of
vessel are entirely shut off from all commu-
nication with other vessels, so as that no im-
pulse could be transmitted from the heart to
them. The necessity of some change in the
tissue of organs or of organizable lymph, in
which new vessels are about to be formed
before the propulsion of the blood into the
new loop of vessel seems sufficiently obvious,

* Dellinger, Journ. des Progrés, &c. vol. ix.
Kaltenbrunner, loc. cit. Baumgartner, Beobacht.
uber die Nerven und das Blut. Freiburg. 1830.

+ [Dr. Tanchose’ suggests as a cause for the mo-
tion of the blood in the capillaries, the ceaseless
removal of ae from the blood to supply ma-
terials to the various secretions, &c. a constant
tendency to a vacuum being thereby produced.
Acad. des Sciences, Séances d’ Avril, 1833.—Ep.]

$¢ See Marshall Hall’s Essay, p. 95; and also
Black’s Inquiry, for judicious remarks upon these
oscillations.

673

but it does not appear to be as yet satisfactorily
shewn that the motion of blood in the new

vessels is independent of a propulsion received
from the heart. Again we consider it as ascer-
tained that the heart of the chick acts just as
soon as any motion of fluids can be seen on
the vascular area of the yolk; and though it
may be admitted that a certain change of place
in the particles of the yolk is necessary in the
new combinations which occur during the de-
velopmentof the forming parts from its substance,
yet such a change or motion must be quite of
an insensible kind and not in any degree ana-
logous to the continued stream of circulating
blood through the vessels.

The stagnation of venous blood in the capil-
laries of the lungs is certainly a most remark-
able and inexplicable phenomenon, but if from
analogy any weight is to be attached to obser-
vations made upon the frog, it may be stated
that the flow of blood through the lungs seems
as immediately dependent on the heart’s action
as that through the system. The portal circu-
lation is not more remarkable in respect of its
isolation from the heart than the systemic cir-
culation of fishes, in which animals the capil-
laries of the gills intervene between the heart
and the systemic aorta; and without any dis-
tinct contraction of that vessel, the circulation
of the blood in the systemic capillaries as
well as in the gills is very manifestly main-
tained chiefly, if not solely, by the action of
the heart. We do not feel inclined to attach
any importance to the alleged motions of the
globules of the blood out of the vessels, for
we have never been able to see any such in-
dicating different powers from those which
produce currents in inorganic fluids, and some
of the observations upon which the statement
is founded have been shewn to be erroneous.

We think it unnecessary to do more than
merely to allude to some of the very many
attempts that have been made to account for
independent motion of blood in the capillaries,
or what have been termed the theories of the
capillary circulation.

All that we know of capillary attraction mi-
litates against the possibility of its being the
means of causing a progressive motion of fluids,
such as that which occurs in plants and ani-
mals. Those who have attributed the motions
of fluids in the living body to endosmosis or a
principle of organic transudation, have failed
in pointing out in the bloodvessels the condi-
tions necessary for the occurrence of a motion
proceeding from an action of this description.
The electrical theory is defective in this essen-
tial point, that no difference in the electrical
condition of the arterial and venous blood has
been shewn, and that the same cause to which
the motion of the capillaries of the systemic
arteries is ascribed ought to retard the passage
of blood in the pulmonary capillaries, the re-
lations of the two kinds of blood being there
reversed. The opinion that the motion of the
blood in the vessels is analogous to those cur-
rents of fluids which take place in contact with
the surfaces of various parts of animals, which
are almost always connected with ciliary mo-

674

tions, and are described under the head of
Cixta in this Cyclopedia, isdefective in so
far as neither cilia nor any power of exciting
currents has yet been shewn to exist in the
interior of the bloodvessels, and they have
been examined in circumstances in which we
conceive they would have been seen had they
been present. In fine we cannot see how any
wer of spontaneous motion belonging to the
lood itself could be a cause of progressive
motion of that fluid, unless the direction of the
motion were determined by the solid textures
containing the blood, and in this case the same
objections would apply to this explanation of
the cause of motion as to the one to which allu-
sion has just been made; and besides, the evi-
dence of spontaneous motions of the blood ap-
pears upon the whole of a very unsatisfactory
kind.

From these considerations we find ourselves
constrained to hold the opinion that, however
great the power which the capillary vessels
eeestip of modifying the distribution of the

lood, there is not reason to believe that they
contribute as a whole to its progressive motion.

4. Phenomena of the venous circulation.—In
the natural state of the circulation the flow of
the blood is nearly quite uniform in the veins,
as may be seen when a vein is opened in the
common operation of. venesection. In those
rare instances in which the flow from a vein is
accelerated after each beat of the heart, in the
same way as the arterial jet, it may be supposed
either that the intermitting impulses of the
heart are, from some circumstance or other,
transmitted more freely and to a greater dis-
tance than usual through the capillary vessels,
as is known occasionally to happen, or, what is
more probable, that the larger branch of the
vein receives the successive impulses directly
from neighbouring large arteries, which are
more than usually dilatable.

As the size of the veins is generally greater
than that of the corresponding arteries at the
same distance from the heart, and as they are
also more numerous, the velocity of blood is
less in these parts of the veins than of the arte-
ries; and as the whole venous system contains
considerably more blood than the arterial, the
velocity of the blood taken as a whole must be
less in the veins than in thearteries. The same
quantity of blood must be brought by the ven
cave to the right auricle as issues from the left
ventricle, (making allowance for the expendi-
ture by secretions, &c.) and consequently the
velocity of the blood entering and of that issuing
from the heart must be equal. Again, the ve-

locity of the blood must be gradually on the

increase in its progress from the small to the
larger veins, because the capacity of the vessels
into which it flows is gradually becoming less.

In the systemic veins, excepting the vene
porte, the direction of the flow of blood is de-
termined by the structure of the valves, which
permit of the return of blood from the extremi-
ties of the veins towards the heart, but oppose,
by the filling of their pouches and the apposi-
tion of their free edges, a complete obstacle to
the reflux of the blood in another direction.

CIRCULATION.

The principal cause of the progressive flow —
of the blood in the veins is unquestionably the —
force of impulsion of the heart continued
through the arteries and small vessels, as ap-
pears from the flow from the remote part of an
opened vein and the simple experiments of

ales, Magendie, and Poiseuille already re- —
ferred to. Hales ascertained, by introducing
tubes into the larger veins of the horse, that the q
pressure on the blood from behind, or vis a tergo,
is sufficient to raise the blood in the tube to a
considerable height above the level of the heart,
and is consequently more than sufficient to re-
turn the blood to the auricle of the heart. The
blood did not, in Hales’ experiments, in ge-
neral at first rise in the tube connected with
a vein more than six inches, but this he
shewed to proceed from the easy escape of
the blood by lateral communicating vessels,
for when the other large veins were tied, or
when they became fully distended with blood,
that fluid sometimes rose in the tube connected
with a large vein to a height of three or four
feet. M. Poiseuille* demonstrated, in a still
more satisfactory manner, the action of the
pressure of the heart on the blood in the veins
by means of the bent tube with which he mea-
sured the pressure of the arterial blood : and
this fact is proved in an equally convincing
manner by Magendie’s experiment of isolating
the principal artery and vein from the other
parts of the limb of an animal, in which it was
found that the flow of blood from the vein is
immediately stopped by pressure or ligature of
the artery. It is scarcely necessary, in order to
obtain a proof of this fact, to have recourse
to the vivisection of animals, for in common
bleeding from the arm, the flow of blood from
the vein will be found to be immediately influ-
enced by the state of the artery, and even with-
out the division of a vein, it is easy to observe
the action of this force of impulsion which
drives the blood onwards towards the heart in
any of the superficial veins of the arm by the
application of external pressure, a mode of
illustration successfully adopted by Harvey in
his explanation of the course of the blood.
These very simp!e experiments are looked upon
by some as quite sufficient to demonstrate the
proposition that the blood is moved in the
veins by an impulsion from behind, and that a
that impulsion is derived from the action of the ‘
heart; while others, not satisfied with this ex-
planation, have endeavoured to point out addi-
tional forces as contributing to the progressive
motion of the blood in the veins.

The larger veins are, like the arteries, highly
elastic, and they are generally regarded as
stronger proportionally to the thickness of their —
coats than the arteries. This elasticity belongs
chiefly to the external cellular coat, for a mid- —
dle fibrous coat is not apparent in most of the —
larger healthy veins, and in those rarer in
stances in which it is apparent, it is ¥
much thinner than in the arteries. The sme
or capillary veins appear also to be poss
of some degree of irritability, for they have bee

* Magendie’s Journ. vol. x.

CIRCULATION.

seen to contract on the application of a stimu-
lus in the web of the frog's foot by Drs. Thom-
son and Hastings. ‘This, however, occurs
much more rarely than the contraction of the
small arteries. It has-been remarked that in
some animals muscular fibres are prolonged
from the auricle upon the adjoining part of the
vena cava; and Spallanzani, M. Hall, Flourens,*
and others have recorded the fact of the rythmic
contraction of parts of the great veins adjoining
the auricles. But, excepting in these situations
and in the caudal heart, observed by M. Hall
in the Eel, muscularity of the veins cannot be
considered as having any effect in promoting
the flow of the blood in these vessels.

The progressive motion of the venous blood
takes place with little force, and is therefore
subject to considerable variations from external
pressure. Thus the flow of the blood may be
much accelerated by raising a limb, or retarded
by keeping it in the depending posture from
the mere effect of gravitation, and the common
practice of making a person who is bled in the
arm call the muscles of the arm into action
during the operation, is a sufficient proof that
the pressure of the muscles may be the means
of accelerating in a considerable degree the
venous circulation,—an effect obviously depen-
dent on the disposition of the valves. Gravita-
tion or muscular action are, however, only occa-
sional causes of the acceleration of the flow of
blood in the veins, and both, but particularly
gravitation, may in some instances offer an ob-
stacle to its progress.

There are some physiologists who believe
the blood to be drawn through the veins to-
wards the heart by a power of suction which
operates from the side of the heart or chest.

e remarks we have already made in treating
of the arterial and capillary circulations render
it unnecessary for us to revert in this place to
the arguments employed by those who have
supported the above view, merely on account
of their belief in the inadequacy of the heart’s
force to maintain the complete circulation ; we
shall only now state the direct experiments or
reasonings by which it has been attempted to
be proved that a vis a fronte or suction power
draws the blood towards the centre of the cir-
culation. We have already, in a former part
of this article, stated our reasons for believing
that the elastic power of the heart itself is not
attended with any production of an appreciable
force sufficient to draw the blood into its inte-
rior.

The facts which relate to the supposition
that the chest or lungs become, during their
motions in respiration, the source of a suction
power which acts on the venous blood may be
suitably considered under the first part of the
fourth division of this article, viz.

IV. THE RELATION OF THE CIRCULATION ~

TO OTHER FUNCTIONS.

1. Respiration—Of the opinions of those
who attribute the suction of the blood through
the veins to powers within the chest, there

* Annales des Sciences Natur. tom, xxviii. p. 65.

675

are chiefly two which have of late years at-
tracted attention,—those namely of Dr. Car-
son of Liverpool,* and of the late Sir David
Barry.t

According to Dr. Carson the lungs are of a
highly elastic nature, and are kept in a state of
forced distension by the pressure of the atmo-
sphere which enters them when the chest dilates.
The lungs would collapse or fall away from the
walls of the chest but for the force with which
they are distended, and there is thus a tendency
to the production of a vacuum within the chest
or to a diminution of the pressure on the exte-
rior of the heart, in consequence of which the
blood is forced or drawn into the heart and
chest on the same principle that fluid enters
the mouth in the act of sucking.

According to Sir D. Barry, at each inspira-
tion of air into the chest the lungs are not suffi-
ciently expanded to fill the whole of the chest,
or there is, in consequence of the expansion of
the walls of the chest, a less pressure within the
chest than on its exterior, and the blood is pro-
pelled through the veins communicating with
the heart by the external atmospheric pressure.

Neither Dr. Carson nor Sir D. Barry state,
in a sufficiently explicit manner, how much of
the force impelling the blood through the veins
they conceive to be of the nature of suction:
they both admit that the greatest part of this
force belongs to the heart or vis ad tergo, but
they yet state distinctly their belief that the
suction power is an important cause of the mo-
tion of the blood throughout the whole venous
system. The works of both these authors are
replete with interesting remarks on the circula-
tion in general, and more especially on the flow
of blood through the veins. The direct expe-
riments, however, in support of their opinions
are comparatively few and inconclusive. Dr.
Carson shewed that the lungs are always during
life in a state of forced expansion, and estimates
the pressure which the lungs of the sheep are
capable of sustaining, when in the expanded
condition, as equal to a column of seven
inches of water. Sir D. Barry observed, in
experiments made upon horses, that when
one end of a tube is introduced into the ju-
gular vein, and the other extremity rests in a
vessel containing water, the water rose during
each inspiration some length in the tube, and
sank again during expiration, distinctly indi-
cating the diminished pressure existing within
the chest at the time of the rise of the water,
and proving that the flow of the blood in some
parts of the veins may be accelerated during
inspiration from the same cause. Poiseuille,{ _
by the employment of the instrument for mea-
suring the pressure of the animal fluids, to which
allusion has already frequently been made, has
confirmed Sir D. Barry’s statement, that the di-
minished pressure within the chest, at the time
of inspiration, is such as to affect the flow of

* Inquiry into the Causes of the Motion of the
Blood, &c. Liverpool, 1815.

+ Experimental Researches on the Influence of
Atmospheric Pressure upon the Progression of the
Blood in the Veins, &c. Lond. 1826.

t Loc. citat.

676

blood in the jugular vein, and to draw it in
some degree towards the heart. In many persons,
particularly the young and those of a thin habit
of body, the jugular veins in the neck are fre-
quently very distinctly seen to become full
during expiration, and to be rapidly emptied
and collapsed during inspiration,—a fact which
shews clearly enough that the blood passing
through this vein enters the chest most easily
when that cavity is dilated. The position,
however, of the body has a very considerable
influence on this rapid evacuation of the jugular
veins in such instances. Again, there are
several direct experiments upon animals which
are much opposed to the views at present un-
der consideration.

Dr. Arnott* has shewn very successfully that
such a power as that supposed to aid the venous
circulation could have very little effect in pro-
moting the flow of fluids through soft tubes,
which collapse as easily as the larger veins do,
because not more than an inch of fluid at the
most can be drawn through one of them by a
syringe, without its sides being brought toge-
ther so as to close the mouth of the syringe,
and this objection is in no way removed by the
circumstance that the veins are kept open by
the vis ad tergo of the heart, because even al-
though they should be open, a force from be-
Jore, to adopt the incorrect expression frequently
applied to a suction power, if strong enough to
make any impression on the flow of the blood,
would act, to a certain amount, just in the
same way as if no force from behind existed ;
that is, it would tend to make the sides of the
vessel come together, and would thus offer an
obstacle to the further progress of the blood.

In repeating some of Barry’s experiments,
Mr. Ellerby+ found that when he introduced
a tube into the jugular vein of an ass for two
or three inches only, there was no suction ex-
erted through it, but that the fluid in which its
further extremity was immersed rose only when
the tube was thrust eight or nine inches into
the vein so as to reach the chest, in which case,
of course, the vein was held open by the rigid
tube, and the suction power was enabled to act
through it to an extent which does not take
place in the natural state of the jugular vein.
Messrs. Ellerby and Davies{ also found that
the venous circulation was for a short time not
materially impeded by opening the chest or
the introduction of tubes into it through the
parietes. It must be apparent to every one that
the suction power or vis ad fronte can exert lit-
tle, if any, force of traction on the blood in the
large or superficial veins of the limbs, for on
making pressure upon the trunks of one of
these, so as to prevent the action of the vis a
tergo, we find that if the limb is at rest the
motion of the blood in the part next the heart
is wholly arrested. But if, while we maintain
the pressure on the vein at one place we empty
the vein for some way towards the heart,
close the vein on the side next the heart, and
then remove the pressure from the remote

' * Elements of Physics, vol, i.
+ Lancet, vol. xi. meee
¢ Lancet, vol. xi. ‘

CIRCULATION.

situation, the blood is at once impelled through
the portion of the vein which had been emptied,
by the force of the heart alone. Messrs. Ellerby
and Davies have shewn that the same pheno-
mena, or the absence of a vis d,fronte and evi-
dence of a vis a tergo, attend the flow of blood
in the largest veins even, which are situated in
the immediate neighbourhood of the chest; for
after the application of a ligature upon the vena
cava inferior, it was found that the part of this
vein between the ligature and the chest was not
emptied towards the heart, and that when the
part of the vena cava in the immediate vicinity
of the chest was emptied, and pressure then
applied at the entrance of the vena cava into
the auricle, the blood rose to fill the emptied
portion of the vena cava, although no suction
power could in this place operate. It was also
found that no fluid rose in the remote extremity
of a tube introduced into the femoral vein.*
These experiments shew that a suction power,
whether produced in the way supposed by Dr.
Carson, or in that stated by Sir D. Barry, can
have very little effect in promoting the flow
of blood in the veins,—a conclusion which is
rendered still more certain from some other ge-
neral considerations, such as the following :

1. The whole of the vessels belonging to the
pulmonary circulation are placed within the
chest, and consequently the flow of blood in
the pulmonary veins must be independent of
any suction power connected with respiration.

2. In the foetus, as there is no pulmonary
respiration, both the pulmonary and systemic
venous circulations go on without any assist-
ance from a suction power. And

3. In the portal circulation of the higher
animals and in the venous circulation of fishes
breathing by gills, as well as of those reptiles
in which air is forced into the lungs by a process
of deglutition, there can be no aid derived from
a suction power. J

We have already, in our description of the
varieties of form im the circulatory organs of
animals, adverted to the intimate relation which
very generally subsists between the structure
and functions of the organs of circulation and
respiration. We shall now mention a few
other circumstances connected with the func-
tions of circulation in the adult human body, ‘
which seem to depend upon this relation of the
motion of the blood to the respiration.

The influence of the mechanical operations
of respiration is not confined to the venous cir-
culation, for it has been shewn by direct expe-
riment that the force of the blood in the arteries
varies also from the same cause, being greater
during expiration than during inspiration. This
greater force of the blood in the arteries —
expiration, known to Haller, Lamure, l
Lorry, was proved by the experiments of Hales, —
Poiseuille, and Magendie{ formerly mentioned.

* See also Macfadyen’s Remarks, Edin. Med.
and Surg. Journal, vol. xxii. p. 271; Carus in
Meckel’s Archiv. iv. p. 413; and Remarks in the
Edin. Journ. of Med. Science, vol. ii. p. 462. _

+ See the late Prof. Turner’s Essay on the Mo-
tions and Sounds of the Heart. Med. Chir. Trans.
of Edin. vol. iii. ;

t Journ. de Physiol, vol. i.

~~

CIRCULATION. 677

It is very probably occasioned in part by the
assistance which the ventricular systole receives
from the collapse of the parietes of the chest at
the time that the air is expelled from that ca-
vity, and in part by pressure of the parietes of
the chest upon its contents, and through them
upon the trunks of the larger arteries. During
inspiration the pressure must be, to a certain
amount, removed from the larger arteries, and
consequently the current of blood through them
at that period will be less forcible and less
rapid.

The well-known fact that rupture of aneu-
risms of the large arteries and effusion of blood
within the cranium in apoplexy are more liable
to occur during straining and other muscular
efforts associated with forcible expiration, is a
further illustration of the fact that the arterial
pressure is greatest at the time of the collapse
of the parietes of the chest.

The relation of the force and frequency of
the pulse to the activity of the respiration is an
interesting subject connected with the facts at
present under consideration.* In many per-
sons, in ordinary and tranquil respiration, the
force and frequency of the pulse vary percepti-
bly during inspiration and expiration, and in
these persons, when the respiration 1s more
forcible than natural, the pulse indicates very
distinctly by its changes the varying states of
the chest. During an unusually long and for-
cible inspiration the beats of the pulse are more
rapid and weaker, and during a succeeding
complete expiration, or even while the chest
is kept expanded, the pulse is more full,
Strong, and slow. Some individuals have the
power of occasioning an intermittent pulse, and
some of causing the action of the heart to cease
even by forcible exertion of the expiratory mus-
cles. We think it probable that it may have
been in this or some similar indirect manner
that the action of the heart was arrested in
Colonel Townsend’s case, described by Dr.
Cheyne in his work on the English malady,
and very often referred to as a proof of the pos-
session by Colonel Townsend of a voluntary
power of influencing directly the heart’s action.

There is in general a very constant propor-
tion in the ordinary state of the circulation be-
tween the number of the beats of the pulse and
the frequency of respiration. The average
number of respirations in a healthy person may
be considered as from 15 to 20 in a minute,
and taking the number of the pulse in the same
time at from 72 to 75, this makes one complete
respiratory motion for nearly four beats of the
heart. The force and frequency of the heart’s
action and consequent state of the pulse are
well known to be considerably influenced by
very slight muscular efforts, as well as by
changes of position of the body even; but it is
not observed that the respiration becomes inva-
riably more or less hurried in a corresponding
degree with an increased or diminished fre-
quency of the pulse. In very violent exercise,
it is true, and more particularly in rapid mo-

_* See an interesting Essay by Hering in Tiede-
mann’s Zeitschrift, vol. v.

tions which give rise to a great and immediate
increase of the frequency of the heart’s action,
the respiration becomes hurried and forcible, or
there is panting; but, on the other hand, it
does not appear that the gradual changes of the
pulse, which are liable to occur from one pe-
riod of the day to another, are accompanied by
corresponding variations in the frequency of
respiration; and again, when by a voluntary
effort we breathe very hurriedly, as for example,
from 80 to 100 times in a minute, the fre-
quency of the pulse is not increased by more
than 8 or 10 beats in a minute.*

Some physiologists hold the opinion that the
motion of the blood in the capillaries of the
lungs and the system is considerably influenced
by the chemical changes which the blood un-
dergoes in its passage through the minute pul-
monary and systemic vessels. We are not ac-
quainted with any facts or experiments which
shew that the systemic capillary circulation is
immediately dependent upon the change of the
arterial into venous blood: on the contrary,
such an opinion is much opposed by the facts
that a free circulation of imperfectly arterialized
blood takes place in the foetus before birth, as
well as in many children after birth affected with
malformations of the heart or greater vessels,
and that a completely venous blood circulates
through the system in hybernating animals
when in the state of deepest torpidity. There
are, however, several circumstances which appear
to justify the opinion that the motion of blood
through the pulmonary capillaries has a more
immediate dependence on the change of arte-
rialization.t In all those circumstances which
cause imperfect respiration and prevent the ac-
customed necessary arterialization of the blood,
or in approaching asphyxia, it seems to follow
from the experiments of Dr. Kay, Alison, and
Reid, that there occurs from the very first com-
mencement of the symptoms of impeded respi-
ration, a diminution of the quantity of blood
which passes through the pulmonary capillaries.
There is thus produced from the first com-
mencement of non-arterialization of the blood
an accumulation of venous blood in the pulmo-
nary capillaries and arteries, but it is equally
well proved that a certain quantity of venous
blcod does, as Bichat shewed, gain the left
side of the heart and permeate the arterial sys-
tem. As the symptoms, however, of suffocation
or asphyxia become more urgent, the accumu-
lation of blood in the pulmonary artery on the
right side of the heart and in the systemic veins
gradually increases, until by the time that the
imvoluntary motions of respiration have ceased,
there appears to be a complete stagnation in the
lungs, although the heart continues to beat a
little longer. During the occurrence of these
changes the action of the heart also is no doubt
gradually becoming weaker, a circumstance
which may very probably contribute to the stag-
nation of the blood in the lungs, but there is good

* See an account of the interesting experiments
by M. Roulin on the variations of the pulse at diffe-
rent heights. Magendie’s Journ. Jan. 1826.

+ See Dr, Alison’s Remarks, loe. cit.

678

reason to think that the motion of the blood
is first arrested in the pulmonary capillaries.

The state of our knowledge does not, it must
be confessed, yes us to offer a satisfactory
explanation of the cause of the above-men-
tioned phenomena. We have already stated
reasons against regarding the stagnation of the
blood in the lungs in asphyxia as attributable
to a loss of the supposed vital power of motion
belonging to the blood in the capillary vessels:
and we think it quite as just to regard the stag-
nation as the effect of over-stimulation and
constriction of the minute vessels of the lungs
by the dark blood, as to attribute it, in the
manner some have done, to the deficiency of
that stimulation which arterial blood, without
any good reason, is presumed by them to give
to the small vessels.

2. Circulation within the cranium.— The
limits of this essay do not permit us to do more
than allude very shortly to the nature of the
circulation within the cranium,—a subject, in
some respects, nearly related to the facts just
stated, and of great importance from the general
dependence of the state of the cerebral func-
tions upon the quantity and force of blood which
flows through the brain.

The bloodvessels within the cranium are dif-
ferently situated from those in other parts of
the body in this respect, that they are removed
from the influence of atmospheric pressure. In
consequence of the unyielding nature of the
skull, and its being closed on all sides, except-
ing at the places where the nerves and blood-
vessels pass through the bones, the cavity of the
skull must. necessarily be equally full at all
times ; and the spinal canal is in the same pre-
dicament.

The whole quantity of fluid or solid matter,
then, within the cavity of the cranium and
spinal canal must be always the same; or,
during the circulation just as much blood must
issue as enters it, and it is physically impossible
to increase or diminish the whole quantity con-
tained in the brain by increased pressure, by
opening of an artery or vein or any other means.
It was shewn by various well devised experi-
ments performed by the late Dr. Kellie,* that
in animals bled to death, while the rest of the
body was exsangueous, the brain retained its
usual appearance so long as the vault of the
cranium was entire, but that a perforation of the
skull, such as to allow the atmospheric pressure
to act upon the brain and bloodvessels of the
head, caused the evacuation of blood from the
head as from other parts of the body.

While the whole bulk of the contents of the
cranium, however, must necessarily remain the
same, yet the relative quantity of arterial and
venous blood may vary within a short space of
time, the pressure exerted by the blood in the
vessels may be greater or less according to cir-
cumstances; and there may occur within the
skull local determinations or partial distribu-
tions of the blood. When from rupture of a
bloodvessel, inflammation, suppuration, or other
causes, blood, serum, or pus are effused into

* Edin. Med, Chirurg. Trans, vol. i.

CIRCULATION.

the cavity of the cranium, the circulating blood
must be diminished in quantity ; when there is
any obstruction to the return of the blood by
the jugular veins, the pressure of the blood en-
tering by the carotid artery is proportionally
greater; and when the arteries which supply
blood to the brain are obstructed, or the heart’s
action is less forcible than usual, the pressure
on the brain must be diminished in a corre-
sponding degree..

In the natural state of the circulation the
pressure exerted by the blood circulating
through the cranium is subject to regular alter-
nations of increase and decrease from the effect
of the heart’s action and the motions of respira-
tion. When the brain of man or of animals is
exposed by the removal of'a part of the skull, it
is seen to be slightly raised at the exposed part
at each arterial pulsation, and more perceptibly
during each expiration. The brain falls again
during each succeeding inspiration, but does
not sink below the level of the skull. These
motions may also be perceived at the fontanelles
of the infant’s head, where the bony parietes of
the skull are deficient. In the closed state of
the skull, for the reasons previously mentioned,
it is obvious that there can be no motions simi-
lar to those observed in the brain when ex-
posed, but nevertheless the brain must be more
forcibly pressed upon by the blood at these
times than at others. Haller, who had observed
these motions, conceived the depression during
inspiration to be caused simply by the ease
with which the blood enters the chest at that
time, and attributed the swelling of the brain
during expiration to the obstacle then offered
to the descent of the blood through the jugu-
lar veins. It seems, however, probable that
the greater fulness of the arteries during
expiration may also contribute to raise the
brain at the time when the collapse of the
walls of the chest occurs: for Magendie ob-
served, that when a ligature was put upon the
jugular vein, the blood which issued from this
vein by an aperture above the ligature, flowed
with greater force during expiration, shewing
that increased arterial pressure during expira-
tion was continued through the capillaries into
the veins. Sign. Ravina, who made a very
extensive series of experiments upon these mo-
tions, found that when the brain has been de-
pressed during inspiration, it again swells,
although no expiration succeeds, but that when
raised during expiration, it does not again sink,
if inspiration does not follow.

3. Influence of varieties in the distribution
of arteries and veins upon the circulation—As
connected with some of the above-mentioned
facts, and exerting a considerable influence in
modifying the circulation of the blood in parti-
cular states of the animal economy, we may
here mention a few of the more remarkable

varieties in the distribution of the arteries and

considered under two heads; a, simple tor-
tuosity; and 6, sudden division into many
small branches. heey ys

ee ee ee ve ee

SO a

+

veins, together with the uses they have been —
supposed to serve in different animals. The —
varieties of form in the larger arteries may be —

i

CIRCULATION.

a. One of the best examples of the first of these
varieties, which are by no means uncommon in
animals, occurs in the spermatic arteries of the
bull. . Two reasons have been assigned for the
existence of this, viz. 1, to allow, by the greater
length of the vessel, for the stretching of parts,
as in the arteries of the lips; and 2, to dimi-
nish the velocity of the blood passing through
the tortuous vessel, from the longer course and
greater incurvation.* Increased friction, which
must be the consequence of greater length of
the artery, will diminish the velocity of the
blood through the whole vessel, and besides
this, a given particle of blood passing through
a tortuous vessel will arrive later at its destina-
tion, in consequence of the longer course it has
to run through; but if we regard the fluid in
the arteries as every where subjected to pres-
sure, it is very doubtful that the increased cur-
vature can be the source of any considerable
retardation by diminishing the force communi-
cated by the impulses of the heart.+

b. The sudden division of an artery into
many small branches may take place with or
without tortuosity or a plexiform arrangement ;
the primitive vessel disappearing or persisting,
but in most cases when present, diminished in
size. The most remarkable examples of this
peculiarity of the arterial system are the follow-
ing. 1. The intercostal and lumbar arteries of
the Cetacea in the posterior part of the chest,
and in the vertebral canal i 9 the caudal artery
of the same animals, which are tortuous and
plexiform. 2. The brachial artery of the Por-
poise, which divides at once into more than
forty plexiform branches. The primitive trunks
disappear, and five or more vessels emerge from
the distal end of the plexus. The uterine and
vesical arteries of the same animal are much
divided, but not plexiform.{ 3. The subdi-
vided brachial sy crural arteries of the Bra-
dypus tridactylus, Lemur tardigradus, L.
gracilis and L. tarsius; and the same arteries,
as well as the caudal arteries of the Myrme-
cophaga didactyla and M. tetradactyla. 4.
The arteries of the legs of the Swan, Goose,
and Turkey divide into several long branches,
which anastomose with one another.§ 5. The
rete mirabile of Galen on the internal carotid
of many quadrupeds, and the rete mirabile on
the common carotid of the Frog. 6. The rete
mirabile of Hovius on the ophthalmic artery of
some animals, the Seal for instance. 7. The
mesenteric arteries of the Sow at their com-
mencement. 8. The subcutaneous arteries of
the Hedgehog.

The uses of these very various forms of arte-
ries it must be confessed is very little known.
Some of them may, like other peculiarities in
animal structure, and more especially those be-
longing to the vascular system, be remains of
the feetal condition of the arteries in which

* J. Hunter.

+ Miiller’s Physiol, vol. i. p. 198.

¢ See the accounts of these varieties by J. Hun-
ter in the Phil. Trans. Sharpey, Meeting of
British Scient. Assoc. in Edin. Sept. 1534. Breschet,
Annal. des Scien. Natur. 1834, Baer, Nov. Act.
Nat. cur. 1835.

_ § Cuvier, Lecgons d’Anat, Comp. vol. iv.

679

they exist.* The most common opinion enter-
tained as to their effect on the circulation is
that they retard the velocity of the blood, and
render its flow more uniform, thus preventing
the parts supplied by them from being affected
by sudden changes.t Other secondary conse-
quences of the diminished velocity occasioned
by these peculiar structures have been imagined,
as for example, 1, diminished rapidity and
greater durability of muscular contraction, as
in the Sloths;{ 2, security against obstruction
of the circulation from pressure, as in climbing
animals which cling long and forcibly to branches
of trees; § 3, or these plexuses have been regard-
ed as intended to increase the capacity of the
arterial system, and to serve as reservoirs for
blood, as may be the case in the Cetacea.||_ In
some of the above-mentioned animals the tor-
tuosity or multiplied divisions of the arteries
are accompanied by a similar condition of the
veins, as in the Porpoise.

The most remarkable variety in the form of
the venous system, and the one to which a use
may be most easily assigned, is the large dila-
tation of the vena cava inferior in the neigh-
bourhood of the liver, which occurs in those
animals which from their mode of life are in the
habit of remaining long under water, such as
the Seal, Otter, and Diving Birds. The pur-
pose of the venous sinuses in these situations is
manifestly to allow of the accumulation of
venous blood in the vena cava without an un-
usual distension of the right side of the heart
and bloodvessels leading into it and from it,
which is the effect of long submersion or im-
peded respiration in animals unprovided with
this peculiarity of structure. The venous and
arterial plexuses of the Cetacea very probably
serve the same purpose. The muscularity of
these sinuses alleged by some must have the
effect of emptying them more easily than would
be accomplished by the vis a tergo.

4. Influence of the nervous system upon
the circulation—It is a very general opi-
nion among physiologists that a considerable
influence is exerted by various parts of the
nervous system upon the function of circu-
lation as a whole, and through it upon the
different processes of the economy concerned
with nutrition, as digestion, secretion, growth,
animal heat, &c. There is some difficulty,
however, in ascertaining the exact relation
which subsists between particular parts of the
nervous and circulatory systems. {t is mani-
fest that in many instances the circulation in
the bloodvessels is modified by a nervous in-
fluence which operates on the heart alone, while
in others it is affected by an alteration of the
vital powers of the bloodvessels themselves.
We refer the reader to the articles Contrac-
Tinity and Hearr for an account of the
modifications to which the circulation is liable
from the operation of nervous influence on

* Baer, loc. cit.
+ Barclay on the Arteries,
t Carlisle, Phil. Trans.
water Treatise.
Vrolik.
, J. Hunter, loc. cit.

. 36.
1800. Roget, Bridge-

680
the heart alone. We shall only remark in
this place that although the heart may be
excited to contraction by the direct stimu-
lation of its muscular substance, and although
the effect upon the heart’s action of bodily
exertion, of emotions of the mind, and of
severe injuries of the brain and spinal mar-
row, all of which can be supposed to act upon
the heart through the nerves only, are un-
doubted; yet it is well ascertained that the
heart cannot in general be excited to con-
traction by the direct stimulation of its nerves,
and that its action may be regarded as auto-
matic to a certain degree, and little dependent
upon the immediate transmission to it of any
nervous influence from the cerebro-spinal or
ganglionic nervous systems, since the rythmic
contraction of the heart continues to go on for
a time in some animals after the division of its
nerves, and in others even after its complete
separation from the body. It has also been
frequently found that after the complete de-
struction of the brain and spinal marrow of an
animal the circulation of the blood can be
maintained for some time by means of artificial
respiration,—an experiment which proves that
the motion of the blood in the vessels is not
immediately dependent upon nervous influ-
ence.*

Many circumstances, however, seem to shew
that the state of the vessels, and in consequence
of this the velocity and force of the blood, are
susceptible of very considerable modification
from local affections of the nerves belonging to
the part in which they may have been observed
to occur, or from general alterations of the
nervous powers of the system. It is probable
that nervous influence operates much more
powerfully in modifying the circulation through
the small than through the large vessels, indeed
we know of no direct satisfactory experiments
which demonstrate the effect of nervous in-
fluence upon the larger arteries exclusively.

The experiments which seem to prove most
satisfactorily the influence of the nervous system
on the circulation in the small vessels are those
performed on cold-blooded animals by Legal-
lois,t W. Philip,{ Flourens, and particularly
those of Marsha!1 Hall,§ the general result of
which may be stated as the following: that after
the destruction, whether sudden or gradual, of
the brain or spinal marrow, the flow of blood
in the remote parts becomes more languid
and is gradually more and more circumscribed,
while the action of the heart continues, and its
power seems not to be diminished in a propor-
tional degree. But in such experiments as those
just mentioned, performed in general in cold-
blooded anima!s, it must be at all times ex-
ceedingly difficult to find an accurate mode of
measuring the force of the heart, and conse-

* We refer here to the experiments of Haller,
Whytt, Fontana, Spallanzani, Legallois, W. Philip,
Clit, Flourens, and Miller; Humboldt, Fowler,
Brachet, Treviranus, Weinhold, &c.

+ Expér. sur le Principe de la Vie.

¢ Exper. Inquiry into the Laws of the Vital Func-
tions.

§ Loc, citat. p. 99.

CIRCULATION.

quently they cannot be regarded as affording

sufficient evidence that there did not occur

along with the languid state of the circulation

a certain diminution in the heart’s Basse

They do not at least entitle us to conclude that

the decreased velocity and stagnation of the

blood in the remote parts is caused mainly by

the loss of the vital powers of the capillary —
vessels, for these changes of the circulation
may ina great measure be the effect of other
causes, as the loss of power of the heart, and
that more permanent alteration of the textures
which very probably accompany the severe
injury done to the body. On the other hand
it may be remarked that the coldness and im-
paired nourishment common in palsied limbs,
the known increase or diminution of the various
secretions from mental emotions, and direct
or sympathetic affections of the nerves belong-
ing to the glands or other secreting organs,
the phenomena of blushing, erection, inflam-
mation, and the like are all very direct and
satisfactory proofs that the small vessels and
the capillary circulation may be influenced by
affections of the nerves. As a further confirma-
tion of this may be mentioned, 1, the inflamma-
tion and other consequences of the division of
the fifth pair of nerves which occur in the eye;
2, the statement of some, as Treviranus, that
the division of the nerves of the leg of a frog
impedes the circulation: 3, the assertion by
others, as Baumgartner, that after the division
of the nerves or the destruction of the spinal
marrow, the peculiar oscillations which he,
along with Doellinger and Kaltenbrunner, has
observed to precede the formation of new blood-
vessels do not occur; and 4, the observations
of Nasse, which are stated to shew that the
reunion of wounds is retarded or put a stop to
by the division of the nerves belonging to the
wounded part. Krimer,* whose experiments
on this subject are numerous and remark-
able, states that the circulation was always much
impaired by the abstraction of nervous influ-
ence from the division or ligature of the nerves;
that the jet from the femoral artery of a qua-
druped was much less strong after the division
of the crural nerve ; that the capillary circula-
tion of the frog’s web ceased soon after the
nerves were cut or tied; that the arterial blood
passed through the systemic capillaries without
undergoing its proper change into venous ;
and that salt did not produce the accustomed
effect of dilating the capillaries when the nerves
of the part were injured, but that these effects
were induced when galvanic irritation was
applied to the divided nerve.

In reference to these experiments it may be —
remarked that most of them are at variance
with experiments of a similar nature performed
by others, more especially those of Haller,
Spallanzani, Whytt, Fontana, Legallois, W.
Philip, Flourens, and M. Hall, none of who!
remarked so immediate and complete a stoppag
of the circulation from removal of the nervo
influence. Again, in palsied limbs the cire
lation is frequently little or not at all disturb

CIRCULATION. 661

and sometimes the secretions, natural growth
of parts, and reunion of wounds have been
found to be little impaired by injuries of the
nerves. We may therefore form the conclu-
sion, that although the circulation in the small
vessels is obviously liable to be modified by
the state of the nerves in their neighbourhood,
or perhaps by affections of the nervous system
in general, there is no reason to consider the
capillary circulation as more immediately de-
pendent on nervous influence than the action
of the heart.

BIBLIOGRAPHY.— We have deemed it advisable
to reserve our historical sketch of the discovery of
the circulation and the knowledge of that impor-
tant portion of physiology to this part of the article,
thereby consulting brevity in uniting it with the
literature of the subject.

The Chinese have been conceived to have enter-
tained correct notions of the circulation before they
had any intercourse with Europe,—a supposition,
the erroneousness of which is sufficiently demon-
strated by their description of the commencement
of the circulation of the radical humours and vital
heat at three o’clock in the morning, their passage
through the lungs in the course of the day, and
termination in the liver at the end of twenty-four
hours, as well as by the different manipulations
practised by them in the operation of venesection.

In the time of Hippocrates and Aristotle, al-
though the principal bloodvessels were described—
apparently from dissection of animals,—the course
of the blood appears to have been wholly un-
known.

Towards the end of the second century Galen
describes accurately the distribution of many of
the bloodvessels in the lower animals. He ap-
pears also to have known the anastomoses of the
arteries and veins, and the structure and uses of
the foramen ovale in the fcetus, but his works
afford no evidence of his having known the course

of the blood in either the pulmonic or the systemic

circulations. He described the arteries as arising
from the heart, the veins from the liver; and some
of those passages of his works in which it is
alleged that the circulation of the blood is pointed
out, are either inconsistent with one another, or
are believed to have been introduced at a later
time than Galen’s. Galen believed that the blood
poe through the septum of the ventricles; he
new that the arteries contained blood, but he
believed its motion to be of an oscillatory kind.
(De usu partium, |. iv., vi., & vii., and his trea-
tise on the question—an sanguis in arteriis naturd
continetur ?

The authors of a more recent date, in whose
works it has been supposed that the circulation was
described, are Servetus, Columbus, and Czsal-
pinus. After the revival of letters, the great ana-
tomist Vesalius of Brussels, in 1542, had examined
more minutely than his predecessors the connec-
tions of the arteries and veins: he mentions the
valves of the veins, the difference between the
veins and arteries, and describes the valves of the
heart. He seems to have known that the blood
was propelled into the arteries by the heart, and
demonstrated by a more direct experiment than
Galen’s, that the arterial pulse depends on the
systole of the heart. (De corporis humani fabrica,
fol, ; and Opera Omnia, cura Boerhaave.)

Servetus, the victim of religious persecution in
1553, is one of those in whose writings we find the
first dawn of part of the discovery of Harvey, for
he very distinctly at one place refers to the pulmo-
nary circulation. The vital spirit (blood) passes
by the arteries into the veins by their anastomoses.
The blood cannot pass from the right into the left
auricle on account of the closed nature of the sep-

VOL. I.

tum auricularum; in the adult it must go through
the lungs, where it is charged with the vital spirit

obtained from the atmospheric air, and then returns

to the heart. He further held that the pulmonary
artery and vein from their large size must have
some other use than the nourishment of the lungs
merely. De Trinitatis Erroribus. Basil, 1531.

Columbus, Professor at Padua and Rome, six
years after the publication of the work of Servetus,
published the discovery of the lesser circulation as
his own. He describes it more clearly than Ser-
vetus does, and held that the blood returning from
the lungs is not mixed with vital spirit, but is quite
pure. Libri xv. De re anatom. Venetiis, 1559.

Cesalpinus of Arezzo, Professor at Pisa, gave,
in 1583, a more detailed description of the pul-
monary circulation than any of those who preceded
him, and in two parts of his work expresses him-)
self in such a manner as to shew that he had some
idea of the systemic and doublecirculation. Other
passages in his works are, however, quite incon-
sistent with a correct knowledge of the course of
the blood, and, although we find this course more
nearly indicated in the writings of Czsalpinus
than in any others before the time of Harvey, he
does not seem to have added much, if any thing,
to the knowledge possessed by those who preceded
him, but rather to have applied, and without
acknowledgement, the observations of Vesalius,
Fallopius, Servetus, and Columbus, to the expla-
nation of the circulation.

The foetal circulation seems to have been ex-
amined with great attention by the anatomists of
the sixteenth century. Galen had already been
acquainted with the foramen ovale, and also knew,
though less perfectly, the ductus arteriosus. Fal-
lopius described the ductus arteriosus exactly,
so also did Vesalius and Aranzii; and after this
Botallus appropriated to himself the discovery of
both the foramen ovale and ductus arteriosus.
Vesalius discovered the ductus venosus which was
figured by Fabricius and Eustachius. Fabricius
ab Aquapendente made the discovery of the valves
of the veins and published it in 1603: it is sur-
prising that knowing their structure so perfectly as
he did, he should have continued ignorant of their
uses, and strictly attached to the older erroneous
opinions regarding the circulation.

Dr. William Harvey was born at Folkstone in Kent,
and studied under Fabricius at Padua from 1598
to 1602. Learning from his master the structure
of the valves of the veins, he engaged in experi-
mental researches after returning to England, with
the view of determining their uses, and in 1619,
according to his own statement, taught publicly for
the first time the doctrine of the double circulation
of the blood, which he had demonstrated by his
investigations. He did not publish any history of
this discovery until after the lapse of nine years,
during which he had carefully examined his doc-
trines and experiments. This appeared in the
Exercitatio Anatomica de Motu Cordis et Sanguinis
in Animalibus, first published at Frankfort in
1628.

Among the contemporaries of Harvey who sup-
ported his views, the following authors are re-
markable.

Werner Rolfink, Professor at Jena, one of the
first to adopt the new view, published two years
after the publication of Harvey’s work.

Des Cartes upon two occasions supported Harvey’s
views, viz. in 1637 and 1643, having been answered
by Plempius.

John Waleus, Professor at Leyden, may be
regarded as one of the most original of those who
adopted and defended the new view. In 1640 he
published two letters, addressed to Thomas Bar-
tholin.

Herman Conring of Hermstadt.

James de Back, Amsterdam, 1649.

John Trullius, 1651, Rome.

eg

682

George Ent of London.

Riolan was the only one of his opponents whose
‘objections Harvey thought it worth while to answer.
This he did in two additional Exercitationes, which
are 8 gt ali in the Leyden edition of his works,
1737. In a journey which Harvey made to Ger-
many, he endeavoured to demonstrate his views
to Hoffinan, bat without success. In 1652 Piem-
pius acceded the merit of discovery to Harvey, and
adopted his views of the circulation. Harvey died
at the advanced age of 79, in the year 1657, after
having had the satisfaction of seeing his views
generally adopted -by the best-informed anatomists
and physiologists, and after having enjoyed the
glory due to so great and valuable a discovery.—-
The best edition of Harvey’s treatise on the Circa-
lation is that tobe found in the edition of his works
published by the London College of Physicians,
in 4to.

About this time the experiment of transfusion,
proposed some time previously, se->ms to have been
‘tirst successfully performed by Dr. Timothy Clarke,
Boyle, and Henshaw, as also by the celebrated
Lower at Oxford, in 1660, affording additional
proof of the correctness of the views or Harvey.

Although the double course of the blood through
the pulmonic and systemic circulations was fully
demonstrated by these investigations, the direct
passage «f the blood from the smaller arteries into
the veins had not yet been observed.

After the introduction of the use of the mi-
croscope, this additional proof was supplied by
Malpighi, who discovered the capillary circulation
in the vessels on the lungs and mesentery of the
frog in 1661 (Epistola de pulmonibus).

Malpighi observed the passage of the globules
of t’e blood through the minute vessels, and thus
satisfactorily proved that there is an actual trans-
mission of the circulating blood ‘rom the arteries
to the veins in both the systemic and pulmonary
circulations.

Lenwenhoeck, in 1673, repeated the observations
of Malpighi on the capillary circulation, and
extended them to different animals, at the same
time adding to their value by the discovery of the
nature of the colouring particles or globules of
the blood (Philos. Trans. No. 102). ‘The structure
of the minute vessels in different parts of the
human body was shortly after this very fully shewn
by the fine injections of Ruysch, and the analogy
between the structure of the minute vessels in Man
and the lower animals thus fully established.

For the history of the discovery of the Circula-
tion, we would refer the reader to the following works.

Bostock’s Elementary system of physiology, vol. i.
p. 343. Haller’s Elementa, vol. i. p 340. Senac,
Traité du ccevr, Introduct. p. 68. Sabatier, Ana-
tomie, ii. p. 255. Portal, Hist. de Vanatomie et
de chirurgie, t. ii. p. 468. Sprengel’s History of
medicine, French, vol. iv. p. 85. Hecher’s
Gerschichte der Medezin, Hecker’s Lehre yom
Kreislauf von Harvey, Berlin, 1831. Barrellotti,
Dialogo sulla scoperta della circolazione del sangue
nel corpo umano, Pisa, 1831.

When the course of the blood in the double
circulation had been fully established by the above-
mentioned observers, and the views of Harvey
were universally adopted, the labours of anatomists
and physiologists were directed to the more minute
and detailed investigation of the different processes
of the circulatory tunction.

The works of Lower, Lieutaud, and Senac on
the heart, and of Hales, Haller, and Spallanzani
on the motion of the blood, were among the more
important of those which appeared during the last
century which contributed to advance the knowledge
of our subject, a. &

The second volume of Dr. Stephen Hales’s
Statical Essays, 1733, contains the history of the
numerous experiments made by that ingenious
philosopher, with a view to investigate the ‘hy-

CIRCULATION.

draulic phenomena of the circulation and the first
accurate measurements and calculations of the force
of the current of blood in the arteries and veins,
its velocity, the power of the heart, &e.

The works of Haller on the cirenlation consist, —

Ist, of the greater part of the first and second
volumes of the Elementa, containing a complete
history of the structure and functions of the organs
of circulation ; y<

2d, Deux mémoires sur le mouvement du sang,
&c. Lausaune, 1756: the first memoir containing
the results, the second a detailed account of the
experiments.

These Memoirs are also published in the Opera
Minora ; also, in English, Lond. 1757.

3d, Deux mém. sur la formation du cceur dans
le poulet, Laus. 1758.

The work of Spallanzani, entitled Experiments
upon the Circulation of the Blood, translated b
Tourdes into French, Paris, An viii., and by R. Hall,
M.D. into English, Lond.1801, contains a great body
of most accurate observations and experiments.

The first two Memoirs are on the circulation
throughout the vascular system.

The next two on the phenomena of the languid
circulation, on the motion of the blood independent
of the action of the heart, and the pulsation of
the arteries.

Circulation in general.— Young on the circulation,
Phil. Trans. 1809. Lund’s Results of modern
Pe Lee vivisections, 12mo. Copenhagen,

825, translated in the Journal Complement.
t. xxiv.-v. &c. Bourdon, Sur le mécanisme de la

circulation, 8vo. Paris, 1820. W. Philip, Phil.

Trans. 1832. MM. Hall, Reply to W. Philip, Med.

Gaz. x. 695. Physiol. of the circulation, Med.
Chir. Review, vol. iv. 1823-4, p. 38. F'lourens,
Mémoires de |’Institut. vol. x. Herbst, De san-
guinis quantitate, 1822. Schwenke, Hist. sanguinis.
J. Wilson, Essay on the blood and vascular system,
Lond. 1819. Kerr, Observations on the Harveian
doctrine of the circulation of the blood, Lond. 1819;
(doubts the Harvéian view.) Charles Bell, An
essay on the forces which circulate the blood,
Lond. 1819. O6esterreicher, Versuch einer Darstel-
lung der Lehre vom Kreislauf des Blutes, Nurnb.
1826. Wedemeyer, Untersuch. uber den Kreislauf
des Blutes insbesond. uber die Bewegung desselben
in den Arterien und Capillargefassen, &c. Hannover,
1828; also in English. Reichel, De sanguine
ejusque motu exper. Lips. 1767. Jaeckel, De
motu sanguinis comment. Vratisl. 1821. Surlan-
diére, Mem. sur la circulation du sang, &c. Paris,
1822. Jos. Swan, Essay on the connection between
the action of the heart and arteries and the fune-
tions of the nervous system, Lond. 1829. Rose,
Diss. de motu sang. naturali et praternaturali,
Helmstad. 1668. Maertens, Diss. de circulatione
sanguinis, Helmstadt. 1739. Araldi, Della forza
e dell’ influsso del cuore sul circolo del sangue,
Mem. della Soc. Ital. in Mod. 1804, vol. xi.

Heart.— Barry on the circulation through the
heart, &c. Annal. d. Se. Nat. xi. p. 113. Boreili,
De motu animalium, 1743. Passavant ( Bernouilli ),
De vi cordis, 1748. Hales’s Statical essays,
vol. ii. 1733. Poiseuille, Sur la foree du cour
aortique, Breschet’s Repert. vi. 1828, and Ma.
gendie’s Journ. Whytt on the heart, Works,
p- 16. Williams on the motive powers of the —
heart, Edin. Med. and Surg. Journ. xxi. 268.
Bartholin on the suction-power of the heart, Anat. —
8vo. p. 371. Senac, Traité du ceur, 1749. Wal-
degans on the same, 1772. A. Welson, Inquiry
into the moving powers employed in the circulation —
of the blood, 8vo. Lond. 1774. Jurin. De
tentia cordis, Phil. Trans. 1718 and 1719. Ja
Keill, Essays on several parts of the animal economy
4th ed. with a Diss. on the force of the heat
8vo. Lond. 1738. Prochaska, Opera Min. 18
Controv. physiol. . -« |

Arteries.—In addition to the works referred to

» 2

-

CIRRHOPODA.

in the Bibliography of ARTERY, the following are
deserving of notice :—Thomson’s Lect. on Inflam-
mation. Roulin on variations of the pulse at
different heights, Magendie’s Journ. Jan. 1826.
Poiseuille on the contractility of arteries, Magendie’s
Journ. vol. viii. On the dilatation of arteries,
ibid, vol. ix. 44. Weber, H. E. De pulsu in om-
nibus arteriis plane non synchronico, Annotat.
Academ. 1835. Jilich. Jager, Tract. anat. physiol,
de arteriarum: pulsu, Wirceb. 1820. Reinarz,
Diss. de arteriarum irritabilitate propria, Bonne,
So Kramp, De vi vitali arteriarum, Argentor.
_ Veins, and connection of respiration with circu-
lation.—-James Carson, Inquiry into the causes of
the motion of the blood, Liverpool, 1815. On the
empty state of the arteries after death, Med. Chir.
Trans. xi. Sir D. Barry, Experimental researches
on the influence of atmospheric pressure on the
flow of blood in the veins and on absorption, Lond.
1826. On the application of the barometer to the
study of the circulation, Annal. d. Sc. Nat. x.
Carus, Remarks on the above theories, Meckel’s
Archiv. iv. 1818, p. 415. llerby, Davies, and
Serle, Lancet, xi. p. 606, &c. Poiseuille, in Ma-
endie’s Journal, x. Arnott’s Physics. H. Marz,
iatribe anat. phys, de structura et vita venarum,
Carlsruh. 1819. Refutation of the theories of
Carson and Barry, Edin. Journ. of Med. Sc. ii.
462. Wedemeyer on the same, Edin. Med. and
Surg. Journ, xxxii. p. 86. Macfadyen on the cir-
culation, in same work, xxii. 271. Wilson Philip
on the effect of derivation in promoting the flow of
blood in the heart, Inquiry, p.9, &c. Lugenbiihler,
_ De motu sanguinis per venas, 1815. J. W. Tur-
_ mer’s Remarks on the same subject, Med. Chirurg.
_ Trans. of Edin. vol. iii. Magendie, Influence of
Respiration on the motion of the blood in the
arteries, Journal, t. i. Bourdon, Rech. sur le
mecanisme de la respiration et sur la circulation
du sang; Paris, 1820. Defermon on the mutual
dependence of respiration and circulation, Ann. d.
Sc. Nat. xiii. 425. Hales on the force of the blood
in the veins, Med. Statics, vol. ii. p.27 & 31.
Flowrens, Sur ja force de contraction des prin-
Cipales veines de la Grenouille, Ann. d. Sc. Nat.
xxviii. 65. Nic. Oudemann, De venarum, precipue
mesaraicarum fabrica et actione, Groning. 1794.
Kellie on the circulation in the head, Edin. Med.
Chirurg. Trans. vol.i. Carson on the same, Edin.
Med. and Surg. Journ. vol. xxi. p. 252.
Capillaries and small vessels.—- Doellinger, Munich
Transactions, vol. vii. and Journal des Progrés.
Do. Was is Absonderung, &c.? Wiirtzburg, 1819.
Gruithuysen, Beitrage zur Physiognosie und Eau-
tognosie, &c. Miinchen, 1812. Organozoonomie,
&c. Munchen, 1811, Kaltenbrunner, Experimenta
circa statum sanguinis in inflammatione, Stutt.
1826. Leuret, on the same, Journal des Progrés.
on the circulation in the small vessels,
Works, p. 211. Schultz, Journal Complément.
vol. 19; also Der Lebensprocess im Blute, &c.
Berlin, 1822. R. Wagner, Zur Vergleich. Phy-
siologie des Blutes, Leipzig, 1833. Bawmgartner,
‘Beobacht. tiber die Nerven und das Blut, &c.
_ Freiburg. 1833. Oesterreicher, Versuch einer Dar-
__ stellung der Lehre des Kreislaufs, Nurnberg. 1830.
_ Marshall Hall, Essay on the circulation of the blood,
_ 8vo. Lond. 1831. J. Miiller, capill. circul. in the
liver of the Salamander, Meckel’s Archiv, xvi.

1829, p. 182. Wedemey
“Meckel’s

er, Additions to his work,
Archiv, 1828, p. 337. J. W. Earle on
the irritability of the small vessels, Med. Gaz.
1834-35, No. 29, p. 70. Kaltenbrunner, Mazendie’s
_ Journ. viii. John Evelyn on the passage of blood
_ from arteries to veins in quadrupeds, Phil. Trans.
xxiii. 1702, p.1177. Molyneux in another volume
of the same. Jas. Black, Essay on the capillary
circulation, London, 1825. Alison’s Outlines of
Physiol. Appendix to 2nd edition, 1836. Hunter
on the blood and inflammation. Thomson’s Lec-
‘ ) ures on inflammation, Edin. 1813, Burns on

683

inflammation. Gendrin, Hist. anat. des inflam-
mations, Paris, 1825. Reuss, Klectrical theory of
the capill. circulation, Edin. Med. and Surg. Journ.
Meyen, De primis vite phenom. et de circulatione
Sanguinis in parenchymate, Berol. 1826. Kruger,
Diss. de theoria physic tubulorum capillar. ad corp.
human. applicatione, Hale Magd. 1742. BG

Influence of the nerves on the circulation.— Trevi-
ranus, Vermischte schriften, i. p. 99. Home,
Philos. Trans. 1814. Flowrens, Action of the spi-
nal marrow on the circulation, Ann. d. Sc. Nat.
viii, 271. | Krimer, Physiolog. Untersuchungen.
Leipzig. 1820. — Exper. sur le principe
de la vie, Paris, 1812. W. Philip, Laws of the
vital functions. Clift on the heart, Philos. Trans.
Brachet, Expér. sur les fonctions des nerfs sym-
pathiques, Paris. Milne Edwards & Vavasseur,
Ann. d. Sc. Nat. vol. ix. p.329. Influence of the
cervical ganglia and their nerves on the action of
the heart.

( Allen Thomson. )

CIRRHOPODA; Cirripedia; Cirripeds ;
(xseeos and gots, cirrus and pes, from the curl-
like form which the coiled feet or arms present.
Fr. Cirripedes. Ger. Rankenfuesser.) A class
of invertebrate animals, composed chiefly of
the barnacles and acorn-shells. They are re-
lated in some points of structure with the annu-
lated or diploneurose animals, particularly with
Crustacea ; in other points they resemble Ace-
phala (Conchifera). All are marine and fixed.
The soft parts are, for the most part, encased
in a multivalve shell. The body is somewhat
conical in form, tumid, and bent inwards at
the oral extremity, tapering towards the oppo-
site extremity, where it terminates in a long
pointed tube. Placed along the abdominal
surface, there are two rows of fleshy lobes,
(six on either side,) each having two long
horny processes, jointed and ciliated. In some
species, these constitute the chief bulk of the
whole animal. The head is indistinctly de-
fined, and has neither eyes nor tentacles;
mouth with lips, and three pairs of horny
jaws; anus at the base of the tubular process.
Respiration is effected by branchiz, which, in
some species, are filamentary, in others foli-
ated. Mantle membranous, sacculated, pro-
vided with a slit-like opening for the passage
of the arms, &c. Between each two pairs of
arms, the abdominal surface is evade by six
slight depressions, which may be regarded as
an approach towards complete articulation.

The animals thus characterized have had dif-
ferent places assigned to them in the various
systematic arrangements of modern zoologists.

uvier formed of them the sixth and last class
of his Mollusca. Lamarck was at one period
inclined to place them amongst the Crustacea,
but latterly he constituted for them a distinct
class, and placed it between Annelida ‘and
Conchifera ; still, however, regarding them as
more closely allied to Crustacea than to any
other class; ‘ for,’”” as he remarked, ‘“ they
have the nervous system of Crustacea, they
have jaws analogous to those of the animals
of that class, and their tentacle-like arms
resemble the antenne of the lobsters.”* Bur-

* An, sans Vertébres, vy. 377.
F.RZ

084

meister also —< them amongst the Crus-
tacea. De Blainville arranges them, under the

name of Nematopoda, as a class of his subtype

of the Mollusca — Mollusc-articulata ; the
other class of the subtype being formed of
the Chitons (Polyplakiphora). He regards

them as Crustaceous Mollusca, but admits
that they seem to form a transition seoup
uniting the Crustacea with the Annelida.
St. Ange,* however, would rather class them
with the Annelida, on account of the closer
resemblance which the arrangement of their
nervous system bears to that of these animals.
Professor Wagner does not doubt that they are
really articulated animals, but he would rather
lace them in a distinct class between the

ollusca and Articulata. Setting aside their
nervous system, M. Serres sees, in the other
parts of their structure, points enough to in-
duce him to arrange them with the Mollusca.
The same views are entertained by Wiegmann,
Goldfuss, and others. Dr. Leach regarded
them as truly annulose animals. Dr. Grant
(who calls them “ entomoid animals enclosed
in shells”) places them amongst the Articulata,
or diploneurose animals, between Rotifera and
Annelida, making of them a distinct class, but
admitting their great resemblance in many
points to the entomostracous Crustacea. Mr.
J.V. Thompson (whose admirable researches
on the development of the Cirripeds have
thrown a new interest around them) holds it as
proved by his observations that the Cirripeds
do not constitute a distinct class; but that they
are naturally and closely connected, on the one
hand, with the Decapod Crustacea, through
the Balanids, and, on the other, with the
Entomostraca, through the Lepads; further,
that they have no relation with the Testacea.

All the known Ciripeds may be naturally
grouped into two families, one pedunculated,
the other sessile. The former includes all the
barnacles, properly so called; the latter, the
acorn-shells. The barnacle family have had
the name of Campylosomata applied to them
by Dr. Leach, who calls the other family
Acamtosomata: but we shall use De Blain-
ville’s synonyms of Lepadicea and Balanidea.
The following are the names of the genera
generally used at present : —

I. Lepapicea.

1. Otion. 2. Cineras. 3. Anatifa. 4.
Pollicipes. 5. Scalpellum.
II. BavanipeEa.
1. Balanus. 2. Ochthosia. 3. Conia.
4. Creusia. 5. Clisia. 6. Pyrgoma.
7. Acasta. 8. Coronula. 9. Tubici-
nella. 10. Chelonobia.

External coverings and organs of support.—
There are three principal modifications of the
tegumentary organs in this class. The first is
that seen in Anatifa, in which it assumes the
form of calcareous plates, united by horny
ligament, and attached to a cartilaginous pe-
duncle. The second form is that common to
all the Balanids—a calcareous cone, composed
of separable pieces, sessile, and provided with

_™ Mém, sur les Cirripédes. Paris, 1835,

CIRRHOPODA.

an opercule of shelly plates. The third form
is a general cartilaginous covering, sometimes
strengthened by small calcareous plates. .
The shells of the Cirripeds are similar in
general appearance to those of many Acepha-
lous Mollusca. They are most fully devel (
in Anatifa, which has five separate plates, four
placed laterally in pairs, and. one median. 2
One pair is conside-
rably larger than the .
other (c, fig. 332); it .
covers all the anterior ‘
part of the animal, and 2
the greater part of the
internal organs. The
bases of these shells
are attached to the car-
tilaginous peduncle;
the lower halves of
their anterior edges
form part of the mar-
gin of the slit-like
opening through which
the arms are protruded
(fre, fig: 332). The
inferior pair of shells
(d) are of a triangular
form ; the smallest side .
completes the margin
of the brachial ori-
fice ; another side is united by ligament to the
upper valve; the third is connected with its
fellow by the common intervalvular ligament.
The median piece (e) covers the dorsal aspect .
of the animal. It has an elongated lanceolate
shape, curved and grooved internally. Its
upper point only is inserted into the peduncle.
Its margins are imbedded in the intervalvular
ligament. This piece may be compared to the
unpaired valve of the shell of Pholas: it oc-
cupies nearly the same situation. The surface
of these shells is generally denuded of epi-
dermis, excepting just around their margins,
All three are strongly and regularly marked
with lines of growth, from which it is seen
that the two pairs of lateral valves increase in
size, chiefly, by additions to their margins,
which look towards one another; so that the
parts first formed are, in the adult animal, re-
moved to the greatest possible distance from
one another. In the upper valve, the umbo or
centre of growth is situated in the anterior-
superior angle, close to the termination of the —
peduncle; in the lower, it is situated in the
anterior-inferior angle; and in the dorsal valve, —
in the point next to the peduncle. All the ©
shells are thin, diaphanous, of nearly the same
thickness throughout, yet much less fragile
than shells of Acephalous Mollusca whie
otherwise resemble them. It has been 1
marked by Burmeister that the shells of C
ripeds resemble those of crustaceous anim
more than those of Molluscs: to us it app
that they have a greater degree of density,
a more compact crystalline structure than
commonly met with in Crabs; and that th
well-marked lines of growth give them a ¢
resemblance to shells of acephalous me

———_—

i iw

CIRRHOPODA.

the five valves just described, there are other
eight smaller calcareous plates arranged around
the junction of the peduncle with the shells.
The shells of the Balanids present several
striking peculiarities of structure, and, in their
mode of growth, offer to the physiologist an
interesting subject for investigation.. They
form truncated cones, the bases of which,
without the intervention of peduncles, are fixed
to rocks, floating wood, integuments of marine
animals, &c. These cones are composed of
several pieces, closely cemented together so as
to admit of no motion between them, excepting
during the process of enlargement of the shell.
In the common acorn-shells (fig. 333), which
cover our litto-
ral rocks and
the bottoms of
ships, there are
seven of these
pieces, six form-
ing the walls,
and one dis-
coid, forming
the base. The
outer surface of
the parietal
valves is mark-
ed by the lines
of growth in
such a manner
as to give it the appearance of being com-
posed of twelve pieces. These may be termed
compartments. ey are all conical. Six of
them have their bases applied to the common
base of the shell, and the other six are inserted
between these, with their apices towards the
common base. The first six we shall refer to
under the name of the first series of compart-
ments (a, a, fig. 333); the other six constitute
the second series (b, b, fig. 333). The opening
in the summit of the cone is closed by an
opercule composed of four shelly pieces so
arranged as to leave a longitudinal fissure be-
tween them, through which the arms are pro-
truded (c, fig. 333). The two series of com-
partments differ much from one another in
their external aspect, owing to the differences
in the directions and appearances of the lines
of growth. The second series have a smoother
surface, and are marked with very delicate
lines, both longitudinal and transverse ; they
are also less prominent than the first series.
The lines on the first series are chiefly trans-
verse, and correspond with the outline of the
base. On the internal surface of the walls
there are six deep grooves, in the bottoms of
which are seen the openings into certain cham-
bers, constituting a sort of diploé of the valves,
hereafter to be described. These grooves run
from the summit to the base of the shell, and
are the internal edges of the sutures of the six
parietal valves. Around the internal margin
of the common base there is a series of holes
Opening into certain tubes that terminate on
_ the outer margin of the shell. When all the
_ yalves are separated at the sutures, it is found
that each of four of the six compartments
of the first series, as they appear externally,

cad

685

has attached to its dorsal margin one of the
second series, and that the union between these
two is exceedingly intimate, in fact that they
form one piece, notwithstanding. their apparent
division externally. Two of the second series
of compartments are attached to the anterior
valve, while the dorsal valve has none. The
anteal margins of the lateral valves and both
margins of the dorsal valve are marked by
transverse depressions corresponding to the
numerous partitions of the chambered com-
partments which are fitted into them; and,
externally, each has a projecting margin. To
the upper part of the inner surface of each valve
there is attached a laminated process, form-
ing part of a circle of calcareous plates which
gives support to some parts of the mantle.

The internal structure of these shells pre-
sents some peculiar features. They all contain
numerous tubes and cavities, regularly ar-
ranged, and forming a sort of diploé. The
suture-holes mentioned above open each into
a separate canal, chamber, or tube. Those
which occur in rows on the walls of the cone
lead to small chambers within the second series
of compartments, running parallel with the
general base, and separated from one another
by delicately-formed partitions, each of which
is deeply grooved on both sides. The par-
titions are placed at equal distances, and their
grooves are most regularly formed. The whole
presents one of the most beautiful and delicate
pieces of structure with which we are ac-
quainted in the whole range of extravascular
skeletons. These are from thirteen to fifteen
on either side of each partition. Fig.334 repre-
sents a perpendicular section
of a few of these grooved par-
titions considerably magnified.
Fig.335 represents a horizontal
section of one of the six valves.
The holes forming the sutures
are at a. ‘The grooved floor
of one of the chambers of the
piece is be-
tween a, d,
andc. d,c
is the outer
wall of the
compartment
of the se-
cond series. a, 6 isa section of that part of
the valve which appears outside as a compart-
ment of the first series. Its diploé is com-

sed of tubes, running from the apex to the
base, gradually enlarging below. Horizontal
sections of those tubes shew them to be of an
ovate form, tapering inwardly (fig. 336). They

are placed nearer
the outer wall than
the inner. The
spaces intervening
between the taper-
ing sides of the
tubes are marked with lines of growth, shew-
ing a gradual filling up of the tubes from
within outwards; and also the previous ex-
istence of furrows or grooves on the surfaces
of the partitions between the tubes. These

‘

686

grooves are very strongly marked in some spe-
cies, as in Balanus Spinosus (fig. 337), where
the tubes are large, and
Fig. 337. ‘the walls comparatively
thin. In all they run in

Tiser7 straight diverging lines
: from the apices of the
compartments to their bases. There they open
close to the margin of the general base. In
most species, however, their orifices are, in
part, filled up by an extension of the base (a,
Jig. 328). In some small species, the tubes of
which are wider than those of larger ones,
there is hardly any opening
discoverable externally, or at
most a very narrow fissure just
around the margin. Very near
their terminations on the mar-
gin, these tubes of the diploe
are joined by the very short
canals which proceed from
the inner circumference of the
hase (6, fig. 338), and it is at
their junction that the grooves
in the walls of the partitions are most obvious.
These two sets of tubes communicate freely all
around the margin with the diploé of the base.
All the Balanids—with the exception of the
Coronules—have calcareous bases. The struc-
ture of the base differs from that of the walls
in being composed internally of large oval
cells irregularly arranged. These cells seem
to communicate freely with one another and
with the tubes of the valves. The Coronules
have no base: their soft parts are in immediate
contact with the integuments of the living
animals in which they are generally imbedded.

The form and arrangement of the opercule
vary. There are generally four triangular
valves, two larger than the others, all deeply
grooved on their upper surfaces by the lines
of growth. These valves cover more or less
completely the soft parts beneath, to which
they are attached, so as to be very moveable
one upon the other, and to admit of the pas-
sage of the feet through the slit that exists be-
tween the two pairs. In some of the coronules,
the greater part of the opercule is soft. Coro-
nula diadema has two small shelly plates in its
opercule.

Keeping in view the complex but beautiful
structure just described, it is not difficult to
determine how the whole shell increases in
size. It is obvious that the parietal compart-
ments of the first series are enlarged by addi-
tions to their basilar edges and internal surface,
and that thus the whole cone is lengthened,
and consequently widened at its base; but,
in all the species, it is also widened above ;
and; as the summits of the first series of com-
partments are, evidently, not at all, or, at most,
very slightly, abraded by the friction of the
opercule, it is certain that the apices of these
compartments—originally very closely approx-
imated—must be moved outwards and sepa-
rated from one another by the gradual increase
in breadth of the intervening wedge-like com-
partments of the second series. This process
implies the insertion of soft parts endowed

CIRRHOPODA.

with vascular action between the valves so as
to admit of lateral additions being made to’
the second set of compartments. There can
be no question that these soft parts (foliated

processes of the mantle) pass into the sutures”
along their whole length, and -deposit the
shelly matter on the edges of the partitions —
forming the chambered structure of the se-

cond series of compartments; each valve, with

the exception of the dorsal one, is thus added.
to in breadth; and as the distance between

the original valves is enlarged, and the whole

shell lengthened, new chambers are formed

below. Of course, as the cone is lengthened,

its base is widened; and this is effected by

the excretion of shelly matter from such parts

of the mantle as can easily pass through the

numerous holes placed around the imner cir-

cumference of the base. The valves of the

opercule are imbedded in the margins of the

mantle between the epidermis and true skin,

and are increased by marginal additions in the

same way as the shells of molluscs.

The mode of growth of these shells engaged
the attention of Cuvier, who concluded that an
addition to the sides of the valves could take
place only in an early age; for it appeared to
him that they are, in a more advanced stage,
so firmly cemented together as not to admit
of separation. In large species, however, we
find that the valves are easily separated at the
sutures, and that the calcareous matter along
the sides of the sutures is loosely aggregated ;
so that, to us, there seems to be no impro-
bability in the supposition that in the living
animal the prolongations of the mantle pass
between the terminations of the minute tubu-
lar processes of the second series of compart-
ments, and the corresponding depressions in
the edges of the first series already noticed.
There is no indication, we think, of each of
the valves being “detached from its neighbour
only at certain times that it may receive addi-
tional calcareous matter along its sides,” as
Brugiéres and Cuvier imagined. The process:
of growth seems to be carried on in uniform
progression until adult age. So puzzling did
the problem of the mode of growth in these
shells appear to Dufresne, that he concluded
that, like crabs, the Balanid casts its old shell,
and forms a new one, as it increases in size.*
Cuvier remarked that, “ while the mode of
growth of the shells of the Mollusca resembles
that of simple teeth, the organization and in-
crease of the shells of balanids may be com-
pared to that of certain compound teeth, par- —
ticularly those of diodons and tetrodons.”

Tubicinella, a parasite of the Whale, differs”
much from the other balanids in the formation
of its shell. The widest part of its six-val
cone is superior; the whole surface is strong
ribbed, and marked with transverse lines ¢
growth; and it appears that the additi
the cone are made on the upper margin 5 th
margin is surrounded internally by a thick a
fleshy production of the mantle, which is nev
alogetsr covered by the opercule. The b

* Ann. du Mus. i. 467. © if a

of

CIRRHOPODA.

is open, and of little less diameter than the
upper part, which led Dufresne to conclude
that the animal does not form a shell until it
be considerably advanced in growth. This
seems to be very probable, as the base is im-
bedded deeply in the integument of the Whale,
and descends lower the more it increases in
size, so as to leave only the summit of the
shell visible. The imbedded portion is gene-
rally deeply coloured by the tegumentary pig-
ment of the Whale. In coronula, which also
inhabits the backs of Whales, but has the same
cone structure of shell as the majority of

lanids, the valves are deeply partitioned,
and provided with toothed processes, fitted to
fix the animal in its site.

The only other calcareous coverings that re-
main to be noticed are the rudimentary valves
in Otion and Cineras, animals that bear a
general resemblance in form to Anatifa, but
which are covered chiefly by a semicartila-
ginous tunic. There are two small valves in
Otion, which are attached to the anterior as-
pect just above the brachial orifice. In Cine-
ras they are five innumber, two in the same
Situation as those of Otion, two along the ter-
minal margin of the outer tunic, and one
ee along the dorsal aspect. These are
imbedded by their margins in the semi-carti-
laginous tunic, and seem to be formed by it ;
calcareous matter being added to their margins
in successive layers.

The ligamentous membrane, by which the
valves in Anatifa are connected one with the
other and with the peduncle, is strong but
_ pliant. It is an extension of the outer cover-
mg of the peduncle. At the brachial orifice,
it is reflected inwards to join the mantle. In
addition to this, each valve has a membrane
of its own, which closely invests its inner sur-
face, and is not continuous with those of the
other valves. The peduncle of this and the
allied genera may be considered as a kind of
developed ligament. If we regard the upper
pair of valves as analogous to the valves of
Acephalous Mollusca, the peduncle is found
to be attached to them at points corresponding
to the situation of the ligament in those shells.
This organ is sometimes of great size. In the
British seas it occasionally occurs two feet in
length. Its epidermis is generally rough,
wrinkled transversely, coriaceous, and elastic :
Otion, however, has it very smooth and stiff,
nearly cartilaginous, diaphanous. In some

ies it is so elastic as to admit of exten-
sive lateral motion, and much elongation and
contraction. These movements are effected by
a layer of strong muscular tissue beneath the
skin, within which there is a large organ,
granular in its structure, regarded by some
anatomists as the ovary. burmeister is of
opinion that the peduncle is merely an organ
of support: and he suggests that the granular
parenchymatous mass, which fills its interior,
is destined solely for its own nutrition, which he
seems to think is independent of the other parts
of the animal. In most species, it is by its epider-
mis that the peduncleadheres. The peduncle pre-

687
sents still other varieties than those just mention-
ed. Pollicipes villosus has itcovered partly with
imbricated scales, and partly with a hairy coat ;
and Pollicipes quadrivalvis has its valves wholly
encased in a large prolongation of the pe-
duncle, which, on its upper surface, bears
four valves arranged nearly in the same wa
as those of the opercule of the Balanids. The
base of Coronula is closed by a strong fibrous
membrane connected with the body of the
animal only by a process of the epidermis.
It is regarded by Burmeister as. the analogue
of the peduncle of the Lepads.

The cartilaginous tunic of QOtion Cuvieri,
at its summit, is enlarged into. two large auri-
form appendages, hollow, having a crescentic
orifice externally, and internally commu-
nicating with the visceral cavity of the animal ;
no organ is discoverable within them, but
their cavities receive the terminations of a duct,
which descends. on the dorsal. aspect of the
body, in the groove of the dorsal valve, from
the peduncle.

Of the mantle, as. one of the tegumentary
organs of the Cirripeds, little more need be
said, than that it is generally a very thin trans-
parent membranous sac, surrounding the vis-
ceral mass, open only at the brachial orifice,
where it joins the epidermis and intervalvular
ligament, and is reflected: so as to form an
inner lining for the visceral cavity. It has
neither fringes of filaments, nor foliated pro-
cesses. M. St. Ange describes another tunic
of the visceral mass, which, he says,. is con-
tinuous with the horny covering of the arms.

Locomotion.—Their base being permanently
fixed, the principal motions of the Cirripeds
are those of the arms, which seem to be sub-
servient at once to the respiratory and: to the
digestive functions. But, as has just been:
mentioned above, the peduncle of Anatifa and’
other allied genera is moved both laterally and:
in the way of contraction and extension, and:
the valves, in the same animals, are: so moved:
as to open and close the brachial orifice. The
motions of the arms are, in many species,
very rapid, and are performed with great re-
gularity; proving the existence of a complete
muscular apparatus. both at their bases and
within their numerous joints; but the parts are
too minute to admit of a satisfactory examina-
tion being made of their structure. The Lepads:
have a strong transverse adductor muscle placed
between their superior valves, just above the
brachial orifice (a, fig.340); this muscle seems:
to be every way analogous to the same organ
in Acephala. Its action closes the brachial
slit very accurately ; while its relaxation admits
of its being opened by the advance of the
arms grouped together into the form of a wedge.
This movement of the arms cannot be per-
formed without the whole body being carried
outwards; which is effected apparently by the
contraction of certain delicate muscular fibres
spread over the mantle, and attached around’
the margin of the orifice. Cuvier describes a_
similar set of fibres, “ attached to the mantle
apposite the insertion of the peduncle, by

the action of which the general mass of the
body is drawn deeply within the shell.”
This we have failed to observe in the a
which have come under our notice. hen
the arms are fully exserted, are separated
one from the other, fan-like. is motion is
robably produced by a muscular expansion,
escribed by M. St. Ange as covering the
visceral mass dorsally, the fibres of which are
grouped into six bundles on either side, cor-
responding to the arms. The same observer
describes also certain tendons which he found
crossing one another at the median line; these
are probably connected with another layer of
muscles, expanded over the dorsal surface of
the visceral mass, fitted to approximate the
arms of either side towards one another. The
muscles of the jaws cannot be satisfactorily
examined on account of their minuteness. In
the Balanids, the valvular opercule is moved
-by a set of muscles attached to the circle of
shelly plates that surround the opening of the
parietal cone. Its adductors, which close the
aperture with great force, are attached to the
extremities of the valves on either side. The
visceral mass is, in the Balanids, fixed to the
shell by three muscular bands, partly attached,
around the mouth, to a process of the epider-
mis, and partly spread over the mantle.
Motility and Sensation —The nervous sys-
tem of the Cirripeds consists essentially of two
nervous cords running along the abdominal
surface, and swelling out into distinctly formed
ganglions, at intervals corresponding to the
feet-bearing lobes. The first pair of ganglions
is situated above the csophagus (fig. 339).
They are united
by a very short
nervous cord. —
From this supra-
cesophageal gan-
glion and the u-
niting cord, there 4
arise anteriorly (¢
three or four —
nerves, which are
distributed to the
muscular tunics.
The principal ner-
vous cords, leav-
ing the first gan-
glion posteriorly,
descend to encir-
cle the csopha-
gus. In this
course, they give
off branches to
the salivary glands and other neighbouring
parts, and particularly, (as M. St. Ange has
pointed out,) a nerve of communication with
a small lateral ganglion (k, k, fig. 339) on either
side, situated near the stomach and below the
salivary organs. This is connected also with
the second pair of ganglions. From this se-
cond pair, several branches arise, some of
which go to the stomach, and two to the first
pair of arms. The other arms receive only
one branch each (i, 7), which is divided into

CIRRHOPODA.

two, one for each of the jointed —
In its course along the abdominal surface,
the double ganglionic cord—the centre of the
nervous system—lies immediately beneath the
skin, between the bases of the arms. The
fifth and the sixth pairs of ganglions have the
ra nae of being closely united. The tu-:
bular process, which terminates the anal ex-
tremity of the body receives two nerves, one
from each of those going to the sixth pair of
arms. Dr. Grant directs our attention to the
fact that all the anterior parts of this system
are very imperfectly developed compared with
the posterior parts, and with the same pai
in other articulated animals, which have their:
heads free, and organs of sense more com-
plete. i

The sense of touch is the only one enjoyed
by the Cirripeds, so far as we can discover.
The ciliated arms of some of the species are
acutely sensitive: they are withdrawn imme-
diately on being touched by any foreign body,
and when the surrounding fluid is unfit for
respiration. Some observers have also re-
‘marked that they shrink from a strong light
brought to shine upon them suddenly. In
the adult animals, there are certainly no
organs which can be regarded as eyes; but,
according to Mr. Thompson, what he be-
lieves to be the free-moving young have very
well developed eyes, like those of some crus-
tacea.

Some of the littoral Cirripeds, when left
dry at ebb-tide, seem to be sensible of certain
changes being produced in the state of the sur-
rounding air by the approach of a living being
to the place of their habitation. We have
frequently remarked, on drawing near a spot
densely peopled by the small acorn-shells that
so abundantly cover most of our rocks on the
sea-shore, a peculiar faint crackling noise, sud-
denly produced, gradually subsiding after the
lapse of a few seconds, and not repeated
until a movement was made towards another
spot; and, on searching for the cause of this
singular sound, we have satisfied ourselves
that it is uniformly produced by the sudden
closing of the opercules of the Balanids, which
seem generally to remain open in ordinary cir-
cumstances. We have seen this motion again
and again follow immediately the movement
of the hand towards particular spots, (not,
however, nearer the shells than twelve or four-
teen inches,) so that we could not but con-
clude that the animal was made sensible,
through the medium of the air, of the pre-
sence of some foreign body, and, fearing dan-
ger, closed its shell for self-protection ; just as
the limpet, warned of the approach of hurtful
agents by the slightest touch of its shell, fixes —
itself more securely to its rocky footing. —
What the nature of the sense is which is thus —
used by the Cirripeds, we have no means of ©
determining.

Digestion—The minute swimming Crus-
tacea appear to constitute the principal food
of the Cirripeds. Sometimes, however, the
shells of minute Mollusca are found in their

CIRRHOPODA.

stomachs, and Burmeister once found part of
an annelid of unknown species. The food is
carried towards the mouth by currents pro-
duced by the rapid motions of the arms,
which, in most of the
species, are constantly
spread out and drawn
in, scr en

t ity. e
oath iarsituated just
at the bottom of the
funnel-shaped cavity
formed by the spread
arms (b, fig. 340). In
the Lepads its position
is close to the trans-
verse adductor muscle.
Its jaws form a round
protuberance, which
presents itself very con-
spicuously immediate-
ly on separating the
arms. t might al-
most be regarded as a
head, so prominent is
it (fig. 341, b,b); but we find it
composed only of the lip and
jaws, with their muscles. The
lip over-arches the jaws; it is
horny, and furnished with minute
palpi. There are three pairs of
jaws. The first or outer pair are
thin horny plates of an oval form,
fringed along their opposing sides
with long stiff hairs. The other
two pairs are curved and deeply
serrated on their opposed surfaces.

The middle ae bears a small
palp on its lateral margin. In

some species, a small tongue has

been found. All these parts bear a close re-

semblance to the same organs in some of the
Crustacea. The cesophagus is short; its lining
membrane is somewhat horny, stiff enough
anently to distend the whole canal; be-

re entering the stomach, its diameter is con-
siderably enlarged. It receives the ducts of
two salivary glands. The stomach (c, fig. 341)
is capacious; externally, it presents an irre-
gular mamillated surface, studded with nu-
merous small prominences closely set, which
are the outer surfaces of hepatic cells, formed in
a layer of glandular tissue that closely in-
vests the walls of the stomach. These cells
communicate directly with its general cavity
(a, fig. 342). There is no other organ that can
be regarded as a liver.* Two cecal appen-

_™ Burmeister’s recent researches have led him
to conclude that both the Lepads and the Balanids
have large livers. He has satisfied himself that

organs, regarded by Cuvier as the ovaries,
and by more recent authorities as the testicles,
communicate by ducts with the upper part of the
intestinal canal, and not at all with the seminal
vessels. Hence he supposes that they are lobes
of the liver and not organs of reproduction. Our
own dissections lead us rather to agree with
Messrs. Wagner and St. Ange, who believe them
to be the testicles.

689

dages, also saccu-
lated internally, and
embossed outwardly,
are attached to the
stomach.

The intestine is
wide, nearly without
convolutions, and ta-
pering towards the
anus (d,e, fig. 341).
In the Lepads the
stomach is situated
in that part of the
visceral mass near-
est to the peduncle ;
from which point the
intestine runs on the dorsal aspect of the body,
and terminates in the anus just at the base of
the articulated tubular process. It is slightly
dilated near the anus. The walls of the in-
testine are perfectly smooth and free from folds
and duplications. The number of their tunics
cannot be satisfactorily determined. M. St.
Ange has described a singular piece of struc-
ture which he has found within the intestinal
canal of certain Anatife (c,c, fig. 342). It is
a kind of second intestine, which floats within
the cavity of the one just described. It is
nearly equal in length to the outer canal. Its
upper extremity is expanded, funnel-shaped,
with edges cut into fringed processes like the
mouths of the Fallopian tube in vertebrate
animals. These processes are lodged in the
cells of the walls of the stomach, and furnish
the only means of attachment to the outer
walls with which the organ is provided. It
thence tapers towards the anal extremity,
where it is pointed and closed. Its walls are
very thin and delicate. It is generally filled
with alimentary matter, which must pass from
its cavity by a kind of rumination, so as to
enter the stomach a second time.

Circulation.—The sanguiferous system of the
Cirripeds has not yet been fully investigated.
Only the vessels of the arms, and a central
canal, situated on the dorsal aspect of the body,
have been discovered. Poli asserted that he
saw a heart pulsating a little above the anus:
but it does not appear that any other observer
has made the same remark. Burmeister has
searched, in vain, for a heart, in the large Coro-
nula diadema. The vessels of the arms can be
distinctly seen through the transparent integu-
ments of the ciliated processes; there are, in
each process, two vessels, one of which runs
very superficially between the two rows of
hairs. ( Fig. 343.)

Cuvier regarded the anterior canal of the
peduncle in Anatifa as the nourishing vessel of
that organ.

Respiration.—The principal organs concern-
ed in respiration are, in the Lepads, certain
tapering filamentary processes attached to the
sides of the anterior part of the body, which
are regarded as the branchie (d, g, fig. 340):
in most of the Balanids, they assume the form
of two leaf-like membranes with fringed mar-
gins, and are attached to the inner surface of

a 690

the mantle. Professor Burmeister describes
the gills of Coronula diadema as broad mem-
branous expansions, of a semicircular form,
attached to the sides of the visceral mass by a
narrow pedicle. They are composed of two
tunics arranged in deep and narrow transverse
pie The number of the branchiz in the

pads varies from four to sixteen. They are
composed of soft cellular tissue, and have a
smooth surface.

The arms (/, h, fig. 340), which constitute
so large a portion of the general mass of all the
Cirripeds, and which form their most distine-
tive feature, must be regarded as subservient
chiefly to the function of respiration; although,
by producing currents in the water, which
bring food within reach of the jaws, they minis-
ter also to the digestive function. In all the
known species, both of Lepads and Balanids,
these arms are twelve in number, six on either
side, arranged symmetrically. Each arm is
composed of a short fleshy peduncle, having
three articulations, and two horny articulated
processes, compressed laterally, of equal length,
ciliated on their internal surfaces, and coiled
up in a spiral of one turn. On their internal
surface there 1s a coating of a black pigment in
spots. Each joint is provided with a double
row of hairs of different lengths. (ig. 343.)

Fig. 343.

A part of one of the arms considerably magnified.

In Anatifa, the first pair of arms is thicker and
stronger than the others; the sixth pair is the
longest. Dr. Grant says, “‘ the arms are not
only minutely jointed to their extreme points,
but, also, the innumerable fine cilia which pro-
ject inwards from their surface are themselves
minutely jointed, and by the aid of the micro-
scope, we can perceive that these jointed cilia
are also ciliated on their margins.”

When the animal is at rest, with the valves
of the shell closed, the arms are coiled up, and
lie close to one another; but, at other times,
circumstances being favourable to the perform-
ance of the function of respiration, they are ex-
tended simultaneously so as to project from the
shell,—radiate and plumose in their arrange-
ment. Many species extend and contract their
arms with considerable rapidity, as often as
forty or sixty times in a minute; the smaller
species more frequently than the larger.

Considering how extensive the surface is
which is exposed in the arms between the two
rows of cilia, and that a vessel seems to run
immediately beneath the delicate covering of
these organs in that situation, it appears proba-
ble that the arms are very efticient agents in the
function of respiration.

Secretion.— We have failed to ascertain satis-

CIRRHOPODA.

factorily the structure of the secreting apparatus
by which the shells of the Cirripeds are formed. -
In the Lepads, the organs must be imbedded
in the ligamentous membrane by which the
valves are united : and in the Balanids, they are
arranged in six rows along the outer surface of
the mantle, and around the base; but, as in
acephalous mollusca, they are too small to ad-
mit of their structure being particularly exa-
mined. The external surface of the mantle in
the Balanids has also the power of secreting
calcareous matter, with which to increase. the
thickness of the shell.

Reproduction.—It is not. yet accurately de-
termined what are the organs of reproduction
in these animals. That which was regarded by
Cuvier as the ovary in the Lepads, is supposed
by Professor Wagner and M. St. Ange to be

the testicle; while Professor Burmeister has

satisfied himself that it is the liver. The ex-
tent, structure, and relations of the ovary are
still doubtful. It is certain, however, that all
the known Cirripeds are hermaphrodite.

The testicle, according to Professor Wagner
and M. St. Ange, is a large granular organ
(y, fig. 344), expanded over the sides of the

visceral mass, and around the digestive canal,
from the stomach to the anus, passing even into
the bases of the arms, immediately beneath the
muscular tunics which cover the body on both
sides. It is composed of numerous minute
lobules, about ;,th of an inch in diameter in
the common Lepads, soft, white, grouped toge-
ther by branched ducts -(q, 9, fig. 344), which,
after uniting into three or four principal trunks,*
meet in a large central receptacle (7), some-
what analogous in relative function to the vas
deferens of vertebrate animals. The seminal
fluid passes from this central receptacle by a
short and straight duct into a large canal (1, #),
which may be compared to the seminal vesicle.
It pursues a tortuous course towards the base
of the tubular process, where (A) it is joined by
its fellow of the other side, and enters the canal

*

* This description does not accord with the result —
of Protessor Burmeister’s researches. Instead of ©
a regular series of branched vessels, he says that
he met with nothing but an irregularly arranged —
mesh of thready fibres lying between what he be-
lieved to be the liver (described above as the testi-

cle) and the intestinal canal. za

CIRRHOPODA.

of the process which forms. a kind of caudal
prolongation of the abdomen (¢’, ¢’). This
canal runs to the distal extremity, and opens
by a minute orifice fringed with very fine hairs.
In Otion Cuvieri the two canals are continued
distinct to the very point of the process, where
there are two openings.* ‘The walls of the
organ, which we have compared to the seminal
vesicle, have a glandular structure, which
Cuvier imagined to be the testicle. The re-
searches of Professor Burmeister have led him
to the same conclusion. He says it can be no-
thing but the testicle-+ Cuvier, as well as
Lamarck, regarded what we have called the
testicle as the ovary, and believed that the ova
were impregnated, in the course of their passage
along the oviducts, by the seminal fluid flowing
from the testicle investing these canals. The
granular lobules of the true testicle, which were
supposed to be immature ova, are found always
in the same state, and what are more distinctly
ova are found within the peduncle. :

The lengthened tubular process (?’, t’, fig.
344), through which the excretory duct of the
testicle passes, is articulated; the margin of
each joint is fringed with minute hairs. In
Otion and Coronula, Burmeister found large
canals closed at both extremities, within the
process, in addition to the ducts from the testi-
cle. This organ is generally found after death
bent upwards on the abdominal surface ; but,
during life, it is in continual motion. Its use
is, probably, to carry the seminal fluid back-
wards beyond the current caused by the move-
ments of the arms, in the event of there being
mutual impregnation between separate indivi-
duals; or towards the mouths of certain ducts
which communicate with the ovary within the
peduncle, in case of self-impregnation taking
place. In this view it must be regarded as
the penis; and it is so called by the most
recent authors on the subject—Wagner and
Burmeister. Mr. Thompson calls it an ovipo-
sitor ; and conjectures that, after their expul-
sion from the ovary, (understanding by this
what we regard as the testicle,) the eggs are
conveyed by it into the cellular texture of the

dicle. How they pass from this depository
mto the general cavity, where they afterwards
form two or three foliated groups, he confesses
himself unable to.explain.

The peduncle of the Lepads was formerly
regarded merely as an organ of support, and
even Cuvier discovered within it nothing but
what appeared to him to be a homogeneous
pulp, surrounded by muscular tissue. But, at
certain seasons of the year, at least, there are,
very distinctly developed, throughout the greater

t of the soft matter which constitutes the

ulk of the organ contained within the dense
cartilaginous and muscular tunics, certain oval
granules, regular, and uniform in shape, and
gradually increasing in size. Poli and Lamarck

* Burmeister, Beitrage, p. 46.

+ Op. cit. p. 44.

¢ Professor Wagner is satisfied that nothing but
the discovery of spermatic animalcules can assure
us against error in our attempts to determine what
is the testicle. .

691

were of opinion that these were truly eggs, but
held that they were originally formed in the
granular organ surrounding the intestine, (now
regarded as the testicle,) and merely deposited
here temporarily. But the recent researches of
Professor Wagner and M. St. Ange have ren-
dered it probable that it is the ovary which is
contained within the peduncle. The organ in
question seems to occupy the whole of the pe-
duncle within the layers of muscular tissue.
It is separated from the visceral cavity by a
fine membrane which lines that cavity, and is a
reflexion of the mantle. A transverse section
of the ovary shews the eggs most fully deve-
loped towards the outer margin, and scarcely
formed in the centre. There are also seen in
the same section two canals which run longitu-
dinally through the organ, one near that side
of the margin which corresponds to the anterior
aspect of the body of the animal, the other in a
similar situation on the dorsal aspect. Of these
canals, the anterior is the larger; and it alone
was described by Cuvier, who regarded it as
connected with the circulating system. The
other was first described by M. St. Ange, who
satisfied himself that it is a true oviduct. In
Anatifa, he traced it pursuing a straight course
through the ovary, and leaving it as a perfect
canal just at the posterior and inferior angle of
the organ, thence passing on the outer surface
of the lining of the visceral cavity, in the groove
of the dorsal valve, and terminating in an orifice
Opening into the visceral cavity not far from the
brachial slit.* We have found a structure
exactly resembling the above in Otion, where,
however, instead of opening into the general
cavity of the visceral sac, the duct is bifurcated
just between the two auriform appendages, into
each of which one of the branches of the duct
enters and opens. M. St. Ange found eggs
in progress through this duct; and they are
frequently found, arranged in groups or packets,
two or three in number, within the cavity of
the mantle. We have not yet seen them in the
duct; but the whole structure of the parts in
question seems to indicate their adaptation to
the function assigned to them by M. St. Ange.
This being the case with regard to Anatifa, it
appears to be very probable that the use of the
singular auriform appendages in Otion is to
afford a convenient lodging for the eggs before
the young are hatched. Their deep sinuosities
and folds seem to adapt them admirably to
this purpose. Packets of eggs, however, are
found within the cavity of the mantle in this
species as in others. According to Burmeister,
these packets are unattached, excepting in the
earliest stage of development; but Wagner has
generally found them fixed to a process of the
mantle, situated near the adductor muscle of

* Professor Wagner says, “‘ at the base of the
dorsal valve there exists a slit in the mantle which
leads into the canal that runs through the peduncle.
I presume that this canal serves as an oviduct, and
that the slit is analogous to the opening of the
branchial canal in the bivalves,’’ (in Archiv fur
Anat. Physiol. &e. von D. J. Miiller, 1834, No. 5,
quoted in Ann. des Sc. Nat. iv. n.s.) We are not
aware what specics was anatomized by Professor
Wagner. ,

692.

the shell ; which process is, at times, so much
elongated as to admit of the eggs hanging out
in groups from the brachial aperture, beyond
the extremities of the arms. Burmeister has
observed that, after the escape of the embryo,
the shells remain connected with the parent,
forming a loose net-work. This author seems
to regard these groups of eggs within the man-
tle, and the tissue in which they are imbedded,
as constituting the true ovary. In each of the
individuals of Anatifa striata which came under
his observation, he computed that there were
about 4000 eggs in the ovary. Mr. Thompson
calls these groups of ova conceptacles ; and
says that “each has a separate attachment at
the sides of the animal to the septum, which
divides the cavity occupied by the animal from
that of the pedicle.”* The retention of their
ova, grouped in separate packets on the surface
of their bodies, after their expulsion from the
ovary, constitutes another point of resemblance
between the Cirripeds and Crustaceous animals.

With regard to the anterior canal within the
ovary, little has yet been determined. We
have particularly examined it in Otion, and
find that, like its fellow of the dorsal aspect, it
leaves the ovary at its inferior edge, whence it
Opens into a small cavity situated between the
intervalvular ligament and the lining membrane
of the visceral cavity. We have not succeeded
in discovering any orifice in the walls of this
cavity, although, from the results of some of
our experiments we think it probable that there
exists a small one just above the brachial slit.
If so, is it not likely that this is the passage in-
tended for conveying the fecundating liquor
from the orifice of the tubular process connected
with the male organs to the ovary? When the
body is exserted through the Lrachial slit, the
point of the process can easily be brought into
contact with the outer surface of the cavity
above described.

The development of the egg and the young
of the Cirripeds has recently become an object
of interesting imquiry in consequence of the
novel results announced by Mr. J. V. Thomp-
son in his “ Zoological Researches,” (1830,
4th Memoir.) This gentleman has published
an account of observations made on what he
believed to be the young of Balanids, from
which he concludes that, on their first exclusion
from the egg, they closely resemble some of
the branchiopodous crustacea,—that they pos-
sess the power of free locomotion through the
water by means of setiferous arms projecting
from within a bivalve shell,—and that they
have very obvious pedunculated eyes. Minute
animals, bearing these characters, and having
some resemblance to species of the genus
Cypris, were placed by Mr. Thompson in a
glassful of sea-water. Soon after, on looking
for them, he could not find them in the water,
but he found in their room several very young
balanids, which, from the appearance they pre-
sented, he concluded to be really the same
animals that he had originally placed in the
water, changed by metamorphosis. Mr. Thomp-

* Phil. Trans. 1835, 356.

CIRRHOPODA.

son has not seen the change actually going on,
but he has satisfied himself that what he re-

gards as the free-moving embryo fixes itself by

a spot on its dorsal aspect between the two

shells, which spot can be seen during its free

state. When fixed, the base of adherence ap- -
pears to be broad like that of an Actinia: from —
this it rises in a conical form,. truncated. The
flat sides of this cone are coated with six shelly
plates, so arranged as to leave a large space in
the middle uncovered. This space is closed
by the old shells of the embryo state, which
are made to move up and down as the opercule
does in the adult animal, admitting of the
egress and ingress of the arms at the animal’s
pleasure. Through this shell two large black
spots like eyes can be distinguished. Mr.
Thompson found in the young of the Balanids,
six pairs of arms, cleft; each arm with’ two ar-
ticulations. The first casting of the shell, after
the animal has fixed itself, is followed by an
increase in the number of articulations in each
arm; and this number is further added to at
every succeeding shell-casting. Even the old
full-grown animals, according to Mr. Thomp-
son, cast their shells.

Very recently Mr. Thompson has made a
still more satisfactory series of observations on
the development of some of the Lepads, of the
genera Cineras, Otion, and Lepas. These he
obtained from the bottoms of vessels in the
harbour of Cork. They hatched eggs in large
numbers, and afforded him the means of ascer-
taining, entirely to his own satisfaction, that, at
its first exclusion from the egg, the Lepad, like
the Balanid, is a natatory crab. He found a
considerable difference between the larve of
the two classes. The newly-discovered one of
the Lepads he describes as “ a tailed monocu-
lus, with three pairs of members, the most an-
terior of which are simple, the others bifid,
having its back covered by an ample shield,
terminating anteriorly in two extended horns,
and posteriorly in a simple elongated spinous
process.”

The general appearance of this larva is not
unlike that of the Argulus armiger of La-
treille.*

Very recently Messrs. Audouin,t Wagner,{
and Burmeister,§ have corroborated the state-
ments and supported the views of Mr. Thomp-
son. Professor Burmeister has detailed the
results of his observations with great minute-
ness. It appears that they were made chiefly
on individuals of Anatifa striata, procured in
the North Atlantic Ocean, and preserved in
spirits ; partly also on Lepas anserifera. (Linn.)
The results of these observations have led Pro-
fessor B. to divide the development of the Cir-
ripeds into five stages or periods. The first of —
these is the state of egg; the second is that of

-
ry

* Phil. Trans. 1835, pt. ii. 355, “* Discovery of
the Metamorphosis in the second type of the Cirri-
peds,” &c. > a

+ Ann. des Sc. Nat. n. s, iii. 31. ae

t Miiller’s Archiv, No. 5, 1834, and Beitrage zur
vergleich. phys. des Blutes. Leipzig, 1833,

§ Beitrage zur Naturgesch. der Rankenfiisser. —
Berlin, 1834. =a t

CIRRHOPODA. 693

free locomotion ; the third is that in which the
young becomes encased in a shell, and fixes
itself; in the fourth stage, the young gradually
assumes the characters of the adult; the fifth
stage is that of perfect development.

First stage-—The egg. Its outer covering
is a very delicate membrane. The yolk is yel-
lowish-red, clouded, and marked with two
rows of small spots, globule-like, distinct at
one end, running together at the other. The
eggs in the central parts of the ovary are consi-
derably further advanced than those in the cir-
cumference. Through the transparent covering
of the egg the general form of the embryo can

seen.

Second stage.—In this stage the young Cir-
riped resembles the fry of Cyclops or Daphnia
in its external characters. It is provided with
two long antennz and three pairs of feet (arms?)
placed along its ventral surface.* Each foot
of the first pair is single, and is furnished with
bristles at its free extremity. Each of the other
pairs is divided into two members, also tipped
with bristles. The posterior part of the body
is tapering, compressed, and slightly bifurcated
at its extremity, where it is beset with bristles.
No eyes could be seen in this stage, but Pro-
fessor Burmeister nevertheless conjectures that
they really do exist. The appearance of two
rows of small globules on the surface of the
body continues to present itself, but here they
are more numerous, although not larger. The
middle part of the body is clear and transparent.

Third stage —Materials for the description
of this stage were obtained by Burmeister
from the examination of only one individual,
which was found attached to the frond of a
fucus hard by the bases of some adult indivi-
duals. The shell, in this the first stage of its
growth, is of leathery consistence, and formed
of one piece, placed dorsally. A fleshy protu-
berance serves as the peduncle. The organs by
which the young animal fixes itself are evi-
dently the long antenne situated near the
mouth. Behind these are placed the very large
eyes. Burmeister satisfied himself of the ex-

istence of a single transparent cornea, and saw

behind it a round black spot, but no lens. The
two eyes are very closely approximated by their
bases. Both the eyes and the brownish con-
tents of the alimentary canal can be distin-
guished through the translucent shell. In the
structure of the posterior part of the body there
is no great change from the former stage. Each
arm of the first pair is single, and consists of
three articulations, of which the basilar is the
greatest: the smallest and terminal one bears
four long stiff bristles. The arms of the follow-
ing pair are not single, but each is divided into
two small articulated processes. The little
globules of the two former stages are not dis-
cernible in this.

“The circumstance of there being a smaller
number of arms in the young than in the adult, re-
minds us of the same heise the case in several of
the Branchiopodous Crustacea; and the want of
the shell in young Cirripeds seems to point out a
closer analogy between them and Crustacea, than
between them and Mollusca, the young of which
are covered with shell in the egg.

Fourth stage.—This stage was observed
by Professor Burmeister in the Lepas anati-
Jera from the coasts of Chili. All the indi-
viduals examined were about three-fourths
of a line in length. Soon after the animal
fixes itself the old integuments are thrown
off. The eyes and the antenne are entirely
cast off along with these. After this process
had been completed, the space within the man-
tle was found to be filled with a granular pulta-
ceous mass, at first occupying the greater part
of the cavity of the shell, and covering all the
young animal. This appeared to M. Burmeis-
ter to be the same that is found in the pedicle
of the older animals, and to resemble closely
the matter contained within the cavities of the
shells of Coronule and other Balanids. It is
by a sack-formed process of the mantle filled
with this yellowish matter that the peduncle is
first formed. At the time of the animal’s fixing
itself the shell has no calcareous points, but. in
the course of this stage it becomes firm and
gradually more and more solid. There are
now six pairs of feet, each of three articulations,
and terminated by bristles. A small tail of
two articulations also appears, the rudiments of
which, however, can be detected in the former
stage. In the fifth stage the process of deve-
lopment is completed.

It must be admitted that the evidence in
favour of Mr. Thompson’s opinions on this
subject is by no means conclusive. There is
still wanting a series of minute and careful ob-
servations on the first appearance and motions
of the embryo immediately after its exclusion
from the egg; and nothing but the results of
such a series can settle the question as to whe-
ther there be a real metamorphosis or not.

Mr. Gray’s observations have led him to
conclude that no great changes of structure,
such as Mr. Thompson’s views presuppose,
actually take place ; although, in examining the
mature egg of Balanus Cranchii, he found the
appearance of the embryo nearly the same as is
described by Burmeister as being that of the
Lepads in the second stage of development.
The egg of this Balanid Mr. Gray ascertained
to be one-fiftieth of an inch in length. He de-
scribes the inclosed animal as being of an ovate
form, tapering at one extremity, truncated and
ciliated at the other; bearing a general resem-
blance to the adult animal, but furnished with
only three pairs of ciliated arms; the base of
each arm being two-jointed. He found only
one lengthened process attached to the lower
pair of arms; but, connected with the two
upper pairs, two fusiform, thick, articulated
and ciliated processes, similar to those of the
anterior part of the perfect animal, but less
prorat He saw no shelly covering.*

We have not yet had proper opportunities of
devoting attention to this interesting subject so
far as observations on the living animals are
concerned ; but we have no doubt of its very
soon meeting with a clear and satisfactory elu-
cidation ; meanwhile we may remark that the
structure of the embryo within the mature egg

' * Proceedings of Zool. Soc. Lond. 1833, -pt. i,
15.

694

(about which there can be no doubt) is such as
strongly to indicate its adaptation to free loco-
-motion ; and that, after a review of all the ob-
servations that have been published on the
subject, we are inclined to conclude in favour
of Mr. Thompson’s opinion that, in the early
stages of its development, the young Cirriped
really enjoys locomotive powers, and then un-
dergoes such changes of structure as are re-
quired to fit it for its altered circumstances in
adult age.

BIBLIOGRAPHY.—Leeuwwenhoek, Opera, iii. 472.
Lister, Exercit. anat. 1696, p. 96. Cuvier, Mém.
pour servir a l’histoire des Mollusques, 1817. La-
marck, Anim. sans vertébres, v.377. J.V. Thomp-
‘son, Zoological researches, 1830; Fourth Memoir ;
-and Phil. Trans. 1835, 355. Wagner, in Archiv
fiir anat. physiol. &c. von D. J. Miiller, 1834,
No. v. Burmeister, Beitrage zur Naturgeschichte
der Rankenfuesser, Berlin, 1834. Martin St. Ange,
Mémoire sur l’organization des Cirripédes et leurs
rapports naturels avec les animaux articulés, Paris,

1835.
(John Coldstream. )

CIRRONOSIS. | (Kiggos, fulvus ; vocog,
morbus.) Ina memoir published by M. Lob-
stein in the first volume of the Répertoire
d’ Anatomie and de Physiologie* for the year
1826, this term was applied to what that author
considers to be a disease affecting the foetus at
an early period of intra-uterine life. The
essential characteristic of the malady consists
in the serous or transparent membranes being
dyed of a_ beautiful deep golden yellow
colour. ‘ The disease is,” says M. Lobstein,
* an internal jaundice of the peritoneum, of
the pleura, of the pericardium, of the arachnoid,
differing from the ordinary jaundice, in that
it does not affect the parenchymatous cellular

tissue of organs, nor the subcutaneous tissue,

nor the skin, the usual seats of that disease.”

Lobstein published the first account of the
occurrence of these appearances in two five-
month fetuses, in his Rapports sur les travaux
executés a l’Amphithéatie d’Anatomie de
Strasbourg.t Since that time additional cases
were presented to his attention, from which he
ascertained that the yellow staining was not
confined to the serous membranes only, but
also was found in the nervous tissues, espe-
cially those of the spinal marrow and encepha-
lon. By the aid of the microscope he perceived
that the substance of the marrow seemed to
be composed, as it were, of small grains of a
lemon yellow colour, mixed with a white and
pulpy substance, as if a very fine gold-coloured
powder had been intimately mixed with a soft
and semi-transparent jelly. In these cases the
thoracic portion of the sympathetic also exhi-
bited a similar colour, and the ganglia were
somewhat swollen, and it was ascertained. by
the microscope that the stain was equally
inherent in the nervous substance of the ganglia
as in that of the spinal marrow,

It is impossible to remove the yellow stain

* Rep. d’Anat, et de Phys,, t. i. p. 141.
+ Page 26, ed. in 4to. ‘

CIRRONOSIS—CONCHIFERA.

from the structures in this condition either by
abiution or immersion for any length of time
in alcohol or water. The intensity of the
colour was not diminished in preparations
which had been preserved in spirits for seven-
teen years, neither was it affected by the action
of light.

The difficulty of accounting for the pheno-
mena which constitute this disease of the
embryo is much increased by the fact that
cirronosis has hitherto been observed only in
three or five month foetuses. As at this period
the biliary secretion has not begun to be formed
in the usual way, we cannot attribute the
occurrence of this disease to any of the causes
which give rise to ordinary jaundice, so com-
monly met with in the fetus at and shortly
after birth. There seems, however, to be no
reason to doubt that the elementary constituents
of the biliary secretion may already exist in
the blood at an early period of intra-uterine
life, and that from them the stain may have
been communicated to the serous membranes
and nervous tissues. But we cannot but
express our concurrence in the opinion of
Andral, that cirronosis differs only in situa-
tion from the ordinary icterus infantum or
neonatorum; there being this remarkable dis-
tinction also, that the tissues which are the seat
of the colour in cirronosis are rarely affected
in jaundice.

Although the observations of Lobstein were
first published ten years ago, I do not find
that they have been confirmed by any subse-
quent observer. The preceding account, there-
fore, of this disease rests entirely upon his
authority, and is drawn up chiefly from his
paper in the Répertoire already referred to.

(R. B. Todd.)

COLLOID. See Scirruvs.

CONCHIFERA. Fr. Conchiféres. When
we take a general view of the organization of
the extensive series of Mollusca, two prin-
cipal classes are readily distinguished, one of
which has been raised to the rank of the pri-
mordial division of the animal kingdom by
Lamarck ; this class, comprising the whole of
the Acephala of Cuvier, as well as the Bra-
chiopoda, has received the name of Concui-
FERA.

The mollusks included in the class of
Conchifera present peculiar characters which
prevent their being confounded in any point
of the series with the other classes of the same
sub-kingdom. They are all contained within
a bivalve shell, generally articulated after
the manner of a hinge; to this shell the
animal is attached by one or several muscles,
and the shell itself is secreted by a fleshy
envelope, generally thin, but having the edge
thickened, to which naturalists agree in giv- —
ing the name of mantle. The animal, of a —
structure more simple than other mollusks, has
no head; the mouth is pierced at the anterior
extremity and is the entrance to organs of di-
gestion, consisting of a stomach, an intestine
of different lengths, an anus, and an organ

CONCHIFERA.

for secreting bile. Circulation is performed
by means of a heart generally symmetrical,
the ventricle of which surrounds the rectum.
Respiration is effected by means of four bran-
chial leaflets, equal in size and symmetrical,
arranged on either side of the body. Gene-
ration is simple; the Conchifera are endowed
with hermaphrodism adequate to the continu-
ation of the species; every individual has an
ovary included among the general mass of the
viscera. The uervous system does not form a
ig ahd ring around the esophagus; ganglia
are found towards the anterior and posterior
parts of the animal, and lateral and very long
filaments form a ring within which the visceral
mnass is included.

Before entering upon the more particular
description of the organs which have just been
mentioned, it is essential as a preliminary to
institute some order among the members of
the class Conchifera, to throw them into a few
grand divisions by which the labour of de-
scription, in many particulars, will be very
much abridged.

Lamarck divided the Conchifera into two
grand orders, Dimyaria and Monomyaria,
We are of opinion that this division may be

- Order

{ First sub-class.
BRACHIOPODA,
or POLYMYARIA

1st.

Second sub-class.
DIMYARIA

se

Order 2nd.

CONCHIFERA.

disjoined

Third sub-class.
L re et d ond order: no

The organization of the Brachiopoda being
more simple than that of the other Conchifera,
renders it proper to place this order at the be-
ginning of the class. The Dimyaria having an
Organization somewhat less complex than the
Monomyaria constitute an intermediate order,
which is the most numerous of the three; the
Monomyaria terminate the series.

To facilitate the comprehension of the brief
descriptions which we shall give of the dif-
ferent parts of the Conchifera, it seems neces-
sary to state precisely the position in which
the animal must be placed in order to be suit-
ably observed. The animal, then, is supposed
to be walking before the observer, included
within six planes to which its different parts
are referred. The head or the oral aperture
indicates the anterior extremity of the creature.
_ This extremity is directed forwards, its pos-
terior extremity backwards. The back cor-
responds to the superior plane; the belly and
_ foot correspond to the inferior plane, and the

lobes of the mantle
more or less united

lobes of the mantle

695

preserved with some slight modifications ; and,
farther, that it is necessary to establish a third
order equal in importance to the two others,
and including the Brachiopoda. The ana-
tomical inquiries of Cuvier, and those, still
more recent in their date, of Mr. Owen into
the structure of the Brachiopoda will not allow
us any longer to regard these animals as per-
taining to the family of monomyary Conchi-
fers. These inquiries also prove that Cuvier,
in forming the Brachiopoda into a particular
class of Mollusca, disjoined them in too great
a degree from their congeners. It is from re-
garding both of these views as carried too far,
that we have been led to propose a new divi-
sion which to us appears to be called for, and
to be preferable to either of the others; this is
to restore the Brachiopoda to the type of pro-
per Conchifera, and to establish a third order
of this family for their especial reception, to
which the title of Polymyaria might be given.
Instead of placing this order at the end of the
Conchifera, however, it appears better to set it
at the head, especially if the analytic method
of Lamarck be adopted as the basis of the
classification. The Conchifera we should, then,
propose to arrange in the following order :

1st sub-order: valves articulated.

Cond sub-order: valves free.

¢ 1st sub-order: shell regular.

The ¢ 1st sub-order : shell regular.
2nd sub-order: shell irregular.
The

ona sub-order: shell irregular.

4 1st order: a foot.

foot.

flanks of the animal to the lateral planes, one
of which is to the right, the other to the left.
The two accompanying figures (fig. 345) will
suffice to give an idea of the relations of one
of these animals to the different planes within
which it is supposed to be included.

The organization of the Conchifera is simple
enough. The researches of anatomists have
shown that these animals are provided
digestion,
circulation,
respiration,
generation,
and (in the greater number)
of locomotion; with a skin
or envelope common to the whole of these
organs; and a nervous system bringing the
different systems into mutual relation with each
other.

Of the organs of digestion—In the Con-
chifera, as among other animals, these organs
begin at the oral aperture. This aperture

with organs of

696 CONCHIFERA.
Fig. 345. Sa hie

aeeene = f

Pe See Pe

on ete ewe nw a we nes See ew pn seme esosesce=

(a, fig. 346) placed at
the anterior part of the
animal is deeply hid-
den between the foot
(b, fig. 346), and the
anterior retractor mus-
cle (c) in the Dimyaria,
and under a kind of
cowl formed by the
mantle in the Mono-
myaria. The mouth is
in the form of a trans-
verse slit, comprised
between two lips, ge-
nerally thin and nar-
row, as in almost all
the Dimyaria, or lo-
bated and digitated,
as in some of the
Monomyaria, (a, fig.
348). The lips ex-
tend on either side in the form of two flat-
tened smaller appendages, more or less elon-
gated, occasionally truncated, streaked or
laminated on their internal surface, and to
which the title of labial palps has by general
consent been given, (d, fig. 346, c, fig. 348.)
The mouth in the Conchifera never presents
any oh that is hard. In the greater number
of these animals it terminates without any
intermediate passage in a stomach, the form
of which is subject to but little variety.
When there is an wsophagus (a, fig. 347), it
is variable both in point of length and capacity ;
it has nothing constant, relatively to the other
distinctive characters of the groups established
_among the conchifera generally: thus it either
occurs or is wanting indifferently among the
individual members of the dimyarian and mo-
nomyarian families.

; a v .

The stomach (b, fig. 347, d, fig. 34

membranous pouch, commonly pee -sl

a ei
ahs Sie a : - Poe ‘ ——- ~—

CONCHIFERA. 697

sometimes globular, rarely elongated and
narrow. When the esophagus exists, it opens
into the upper part of the stomach; but
when that canal is absent, the mouth termi-
nates directly in the stomach. Examined
internally, the stomach presents several de-

ressions irregularly dispersed over its surface,
by means of which the bile is brought into
its cavity; it is on this account that these
minute depressions have received the name
of the biliary crypts. The intestine (c, fig.
347, e, fig. 348) arises from the posterior
wall of the stomach, and a very singular ap-
paratus is occasionally found in its vicinity
(d, fig. 347), the use of which is not yet de-
termined. It consists of a small appendage
which may be compared to the vermiform
process of the cecum in the higher animals;
It communicates with the stomach, and is filled
by a horny process or stylet of different lengths
and thickness, according to the genera and
species examined. The anterior extremity of
this body is attached to the parietes of the
stomach by means of small extremely thin and
irregular auricular processes (oreillettes ). It is
to be presumed that quantities of the food may
fall during the act of digestion between the
parietes of the stomach and the horny body, by

it to be pressed or bruised in some particular

manner. Yet when those conchiferous ani-
mals which are furnished with the apparatus
just mentioned, are examined by dissection,
no particle of food is found in such a position.
We may therefore be allowed to conjecture
that this part accomplishes some other purpose
in the economy of the conchifera. Whatever
this may be, it must, we should imagine, be
connected with the function of digestion.

The intestinal canal in the conchiferous
Mollusca is generally slender, cylindrical, and
from one extremity to the other almost always
of the same diameter. After having made a
variable number of convolutions within the
substance of the liver and the ovary, the in-
testine comes into relation with the dorsal and
median Ime of the animal’s body. It con-
tinues in this direction to the posterior extre-
mity, there to terminate in the anus (e, fig. 347,
SF, fig. 348); the whole of this dorsal part of
the intestine is named rectum. The rectum is
generally longer in the Dimyaria than in the
Monomyaria, because the anus is found above
the superior adductor muscle in the former,
whilst in the Monomyaria the rectum twists
round behind the central muscle to terminate
in an anus which floats between the edges of
the mantle.

The liver (f, fig. 347, g, fig. 348) is a
bulky organ enveloping the stomach and part
of the intestine. It pours the product of its
secretion directly into the stomach by means
of the biliary crypts. The liver alone con-

_Stitutes a very large portion of the visceral

mass, and consequently of the body of the
animal; it consists of a great number of fol-
licles connected together by means of lax and
extremely delicate cellular membrane; this

‘Structure renders the organ very easily torn.

We shall see by-and-bye that it is traversed in
VOL. I. |

the greater number of mollusks by several
muscles belonging to other parts, an arrange-
ment which contributes to support and give it
greater strength.

The exposition which has now been given
of the structure of the organs of digestion,
affords a ready explanation of all that bears
upon this function in the conchiferous mol-
lusca. These animals not having the mouth
armed with any hard part are unable to seize
and swallow any kind of solid food, so that in
general nothing more is found in their sto-
machs than segregated particles, proceeding
without doubt from the decomposition of
aquatic animals and plants. The lips, and
unquestionably the labial palps also, are de-
stined to give the animal perception of the
aliment it takes. Once in the stomach, this
aliment, impregnated with bile and probably
also with a gastric juice secreted by the lining
membrane of this pouch, is subjected to a
first digestive elaboration; it next passes the
pylorus when it exists, and then traverses the
intestinal canal and supplies to the absorbent
system the elements necessary to the nutrition
of the animal.

- It does not appear that there is any par-

ticular system of absorbent vessels in the con-

chiferous Mollusca; the veins perform the

office of absorbents, and they transmit with-

out any intermedium, and kegsebin ice under-
Z

698

going any glandular elaboration, the fluids ab-
sorbed to the general current of the circulation.
After having thus had all the nutritious ele-
ments it contains abstracted, the alimentary
mass, having reached the rectum, there com-
monly presents itself under the form of minute
globules ; it is soon afterwards expelled through
the anus.

Organs of circulation——The organs of cir-
culation in the acephalous Mollusca consist
of two vascular systems forming together a
simple circuit, namely, a ventricle and an
arterial system, and a venous system and two
auricles. The ventricle in the majority of
acephalous mollusca is single, symmetrical,
situated in the dorsal median line of the body,
and rests upon the rectum, which it embraces
in its evolution (g, fig. 347, h, fig. 348) on
every side so closely, that the itestine appears
to pass through it. It is to be presumed,
however, that the intestine does not pass im-
mediately athwart the heart, but that this canal
is only embraced so intimately by the central
organ of the circulation, that it is impossible to
separate without tearing them. The ventricle,
which is regular and symmetrical in the greater
number of the genera (a, fig. 349) is irregular
and unsymmetrical in the Ostracean family, (a,
iz. 350). It is generally elongated and fusiform ;

Figs. 349 & 350.

ING
a

i)

its parietes are thin, formed of muscular fibres
variously interlaced, and often projecting in-
ternally. From either extremity issues one of
the two main arteries of the body, the one
superior giving branches to the whole of the
anterior parts of the animal; the other pos~
terior supplying branches to the principal vis-

CONCHIFERA.

cera,—the stomach, liver, intestinal canal, and
ov Many superficial branches penetrate
the mantle, and may be observed ramifying
more especially upon the thicker parts which ,
constitute its edges. .

When the back of the animal is very broad,
and as a necessary consequence of this struc- —
ture, the branchi of one side are at a consi-
derable distance from those of the other side,
we find, as among the Archide, that there are
then two ventricles (a, a, fig.351,) and two auri-
cles (b, b, fig. 351) to secure the perfect per-
formance of the important business of circula-
tion. This interesting modification of the organs
of circulation is of slight significance as
the mere results of the function, for it still con-
tinues no more than a simple circuit, exactly
as if it were effected by a single ventricle.

The auricles are two in number (8, |,
Jigs. 349 & 351, i, fig. 348) in the whole
of the genera of Conchifera except those of
the family of the Ostracea, in which there
is no more than a single irregular auricle
(6, fig. 350), just as there is but one ventricle.
The most general figure presented by the au-
ricles is the triangular. They communicate
with the ventricle by one of the angles of the
triangles, and they receive the blood of the
branchie by the most extensive of their three
sides. These organs are altogether membra-
nous; in their interior, however, we discover,
with the aid of the magnifier, a great number
of small fibrous fasciculi, by means of which
the regular contraction of the ventricles appears
to be effected.

The venous system is of very considerable
magnitude. In his magnificent work, Poli*
has given a very satisfactory account of its
anatomy. It is more particularly remarkable
in the Archide, the Pinna, &c. It is destined
to receive the blood of the general circulation ;
it is also destined to collect the whole of the
fluids absorbed, and to direct these towards
the branchial apparatus, in which the blood
with these added fluids undergoes a fresh
elaboration. It is after having traversed the
branchial vessels (c,¢,¢, c, fig. 349, 351, 7,
jig. 348) that the blood revivified is carried to-
wards the auricle by the pulmonary veins, from
whence it is sent to the ventricle, and by it foreed
anew to perform the round of the arterial cir-
culation,

The blood in the Conchiferous mollusks is
colourless, or of a bluish white, very different
from the hue it presents in the vertebrata ;_
it is but slightly viscid, and when it coagulates
exhibits but a very small quantity of crassa=
mentum or solid matter.

Circulation then is an extremely simple —
function in the Conchiferous mollusks: an
aortic ventricle gives the blood impulse enough —
to carry it through the two systems of vessels,
to expel it from the heart and to bring it ba
again to the auricle. In other branchiferous
animals, the auricle is sometimes adapted to
give the blood a new impulse when itis about
to pass through the branchiz ; here, on th

: : roe
* Testacea Utriusque Sicilia, fol. 3tom.

CONCHIFERA.

\
\

contrary, the auricles do not receive the blood
until it has been exposed to the revivifying
influence of the organs of respiration.

Of the organs of respiration— The whole

of the Conchiferous mollusks respire by

means of branchie (e, e, fig. 346). These or-
gans are variously sippones according to the
orm of the animal. They are symmetrical ;
and in almost all the genera there are two on
each side. The branchie generally present
the form of membranous leaflets, of a qua-
drangular shape, though often unequal. They
are broad and short when the animal is glo-
bular, elongated and narrow when the animal
is lengthened in its general form. In the

ter number of genera the branchie are
ormed of two membranous layers or lamine
(bs Jig. 352) within the substance of which

branchial vessels descend with great regu-
larity. In several genera, as the Archide and
Pecten, the branchial vessels, instead of being
_ connected parallel to one another within the
thickness of a common membrane, continue
unconnected through their entire length, and
_ they are thus formed of a great number of
extremely delicate filaments attached by the
_ base within a membranous pedicle, in which
the branchial veins pursue their way towards

699

Fig. 352.

is

the auricle. In a great many families and
genera the branchie of one side have no com-
munication with those of the opposite side ;
in some others however, as in the genus Unio,
the four branchial laminz meet under the foot,
and the whole of their vessels empty them-
selves into a venous sinus of considerable
size. .
222°

700

A remarkable phenomenon is observed in a
great many of the Conchiferous mollusks: the
eggs on escaping from the ovary, instead of
being cast out altogether, are deposited between
the two membranes of the branchial lamine,
and there undergo a kind of incubation,
during which they acquire a considerable size.
In some genera, such as the Unio, the shell
is even developed within the egg before this is
cast loose from the branchiz, and this cireum-
stance has led several anatomists to mistake
these small shells for parasites. As in all the
other animals having branchie, the organs of
respiration are destined to restore to the blood
the oxygen which it had lost in its circulation
through the body. This necessary element to
the maintenance of life is restored to it during
its passage through an organ contrived so as to
bring it almost into contact with the ambient
fluid in which a considerable quantity of atmo-
spheric air, and consequently of oxygen, is
found dissolved.

Organs of generation.—The organs of ge-
nération are of extreme simplicity in the Con-
chiferous mollusks, They consist of an ovary
included in the visceral mass. Nota trace of
any other organ of generation can be detected,
and the Conchifera must therefore be allowed to
possess what has been called sufficient herma-
phrodism, generation in them taking place
without coition. The ovary is a glandular
mass situated at the superior and posterior part
of the body; it is in connexion with the liver ;
and it often receives a portion of the intestine,
if it happens to be developed laterally between
the two fleshy laminz which form the walls of
the foot. In thesiphoniferous acephala having
the foot short and rudimentary, the ovary, in
its state of complete development, forms a very
great part of the abdominal mass, amid which
it is easily distinguished by its soft consistency
and yellowish white colour. In those acephala
in which the siphon is short and the foot well
developed, the ovary forms a mass less promi-
nent at the superior and posterior parts of the
viscera. In the Conchifera monomyaria the
ovary resting upon the central muscle is situated
in the upper and posterior part of the body,
and in its state of development constitutes a
whitish mass of considerable size, which is
readily seen in the Ostracea through the walls
of the mantle. This ovary occupies the whole
superior part of the animal, and it is seen de-
scending along the lateral and posterior parts
when the animal is exainined at the time of
jaying its eggs; a rent in the ovary allows a
fluid of a mjlk-white colour to escape. This
fluid under the microscope is seen to contain a
very great number of small whitish granules,
each of which is an egg capable of reproducing
an individual similar to that from which it de-
rives its origin,

There is a singular genus placed by the
generality of writers in alliance with the
Oyster, .and designated by the name of
Anomia, in which the ovary forms no part of
the common mass of the viscera, but extends
between the two walls of the mantle, which it

CONCHIFERA.

separates in proportion as it increasés in size.
This position of the ovary in the substance of
the skin is analogous to what is observed in the —
Terebratule, in which the ovary is divided into
four segments comprised within the substance

of the mantle and in the direction of the prin-
cipal branchial vessels.

Notwithstanding the minute dissections —
which have been made of the acephalous —
mollusks, there are a great many in which —
the oviduct remains unknown. In two of —
these animals in which it has been sought —
for in vain, it has yet been seen running to-
wards the middle and anterior part of the
branchiz, and opening to the right between the
folds of this side. It is not yet known whether
or not it be by this opening that the ova escape
after they have undergone incubation in the
branchie, or whether they escape by the edges
of these organs.

M. Prevost of Geneva has made some
important observations on the generation of
the Uniones, which appear to prove that
although coitus cannot take place between
the acephala, it is nevertheless necessary to
their propagation that a certain number of these
animals be found together near the same spot. _
From these experiments we may infer that a
fecundating fluid is diffused in the water and
absorbed by the ovary, which is thus fecun-
dated without the contact of two individuals.
This phenomenon is comparable to that which
we know takes place in the fecundation of the
ova of fishes ; these are deposited by the female,
and afterwards sprinkled by the male, who
places himself above them, with the prolific
fluid. Before adopting definitively the results
of M. Prevost’s experiments, however, it were
necessary to repeat them a great number of
times, in order to leave no doubts on this ques-
tion, so interesting to the naturalist as wellas
to the physiologist, touching the generation of
the hermaphrodite mollusca.

The number of eggs extruded by each in-
dividual is very great, and explains the rapidity
with which these animals are propagated in
certain seas, and the production by accumulated
generations of those extensive beds of shells
which are so frequently found covering the sur-
face of actually existing continents. J

Organs of motion ——The organs of motion —
are of two kinds: one is destined to move the —
two valves with which the animal is covered; —
the other is peculiar to a special organ, by
means of which the animal moves its whole —
body. The muscles may therefore be arrang .
into two classes: 1st, adductor muscles of the
valves; 2d, locomotory muscles, or muscles
proper to certain organs. Those fleshy and

fibrous fasciculi attached between the tw
shells, and which by their contraction approx
mate and close these two shells, are denom

ted the adductor muscles. In the greater nu
ber of the conchiferous mollusca, two of th
muscles can be demonstrated, the one ant
(c,fig. 346; h, fig. 347; a, fig. 362) situ
in front of the oral aperture, and the other
terior (f, fig. 246; i, fig. 347; b, fig.

CONCHIFERA. ‘

Lamarck has given the title of Dimyaires to all
the mollusca having two adductor muscles, a
character which he has invested with a consi-
derable degree of importance, because it is con-
stantly proclaimed by the interiors of shells,
upon which the impression left by these mus-
cles is very distinctly seen (a, b, fig. 367). One
of these muscles, the anterior, diminishes gra-
dually as we descend in the series of the Con-
chifera; in the family of Mytilacea it only
exists in a rudimentary state (a, fig. 353); and
after these it disappears entirely. In propor-
tion as the anterior muscle disappears, the pos-
terior one increases in size, and approaches
more nearly to the middle of the valves. When
no farther trace of anterior muscle can be dis-
covered, the posterior muscle continues singly
(k, fig. 348), and the mollusca having a single
muscle, very distinct from the former which
have two, have received the name of Mono-
myaires from M. Lamarck.

_ Poli, however, has shewn that the muscle of
the Monomyaria consists in reality of two por-
tions, readily separable from one another, and
even differing considerably in their appearance.
This leads us to presume, with every show of
reason, that the single muscle in the Mono-
myaria is the result of the approximation of the
two muscles, which are parted in the Dimyaria.
This fact would incline us to regard the num-
ber of the muscles as a matter of but small im-
portance in the classification of the conchiferous
mollusks, and we may suppose that it was with
Such inductions before him that Cuvier was
led to attach such slight significance to the
division of these animals proposed by La-
marck.

The organ denominated foot in the acepha-
lous mollusks is a part which presents very
different forms, and is destined to locomotion.
This part is particularly well developed among
the Dimyaria, and we shall pass in rapid re-
view its most general features.

The foot (b, fig. 346) is usually situated at
the anterior and middle part of the abdominal
mass, and is directed forwards. It is so placed
as to hide the mouth in a deep sinus between
its base and the anterior adductor muscle. In
those conchiferous mollusks in which the lobes
of the mantle are united through a great por-
tion of their circumference, the foot is com-
monly very small and merely rudimentary ; it
then forms a kind of little nipple projecting
from about the middle of the abdominal mass,
a form which is very distinctly seen in the
_ Mya, Saxicava, &c. In others of these mol-
_ lusks the foot, more anteriorly situated, is ex-
tremely short, broadly truncated, and similar to
_ acupping-glass; this configuration is observed
in the Pholadia. In proportion as the foot be-
- comes more free, the lobes of the mantle are
distinct from one another, the foot becomes
flattened and elongated in the form of the
human tongue, and is subservient to motion
by digging a hole or furrow in the sand into
which the animal sinks. This form of the
_ locomotory organ is met with more especially

in the Tellina, the Donata, and a very great

70 1,

number of other genera, the shells of which are
more or less flattened. Lamarck had attached
some consequence to the shape of the organ of
locomotion, and Goldfuss has proposed a clas-
sification based upon the modifications pre-
sented by this organ ; but the groups establish-
ed in accordance with such considerations are
in reality of no importance; the several forms
proper to the organ pass too insensibly one into
another to make it possible to say where one
terminates and another begins ; the boundary
between one family and another, with a few
rare exceptions, is altogether indefinite. In the
present day, consequently, naturalists no longer
admit into their methods of arrangement the
groups established by Lamarck under the
names of Tenuipeda, Crassipeda, &c.

The foot exists developed in a greater or less
degree in the whole of the Dimyaria. If in
some species it is found merely rudimentary, it
is yet never altogether wanting in any member
of this first division of the Conchifera. The
organ is also met with in a very considerable
number, but by no means in the whole of
the Monomyaria, and the presence or absence
of the foot might be taken as the basis of a
division of this great family into two series, in
the one of which the foot was rudimentary but
present, whilst in the other it was no longer to
be found.

Whatever the forin of the locomotory organ,
and whatever the degree of its development, it
is always organized in the same manner. It is
essentially composed of several planes of mus~
cular fibres (1, 2, 3, fig. 347), which by their
various courses and interlacements enable it to
perform a great variety of different motions,
either in part or as a whole. When the foot is
short or vermiform, its mass is entirely muscu-
lar from the apex to the base. It is at the base
that the fleshy fibres separate into two fasciculi
(4, 5, fig. 347), which, after having circum-
scribed the visceral mass, proceed backwards,
where they are attached to each valve of the
shell near the implantation of the posterior ad-
ductor muscle in the Dimyaria; and towards
the superior part of the valves, and occasion-
ally in the interior of the hook, or incurved
part of the shell in the Monomyaria.

In the Conchifera denominated Lamellipeds
and Crassipeds by. Lamarck, in a word, in
the whole of the Conchiferous mollusks in
which the foot constitutes a principal part
of the body, this organ presents remarkable
differences in its composition and its rela-
tions with the internal organs. It is then
formed of two lateral planes of fibres, uniting
and blending together near the free edge.
These two planes, more or less separate ac-
cording to the general form of the animal,
have between them an internal space, within
which is included a considerable portion of the
visceral mass. In the generality of conchife-
rous mollusks furnished with a large foot, it is
here that a portion of the liver is situated, the
greater part of the intestinal canal, and a
notable portion of the ovary. These organs are
bound down in the place they occupy, and the

702

parietes of the foot are preserved in immediate
communication by means of a great number of
small muscles, sometimes straight, sometimes
oblique, and variously interlaced, to which
Poli has given the name of funicular muscles
(j, Jj, fig. 347). They are particularly conspi-
cuous in the cylindrical foot of the Solens, in
the flattened foot of the Telline, and of the
Uniones, and they have a remarkable arrange-
ment in that of the Cardie. They appear to
be wanting in the foot of those Conchiferous
mollusks that attach themselves by means of a
byssus. In them the foot is reduced to the
functions of spinning (de filer) the threads of
the byssus, and it is not therefore surprising
that its organization should be found to be
peculiar. Reduced to a purely rudimentary
state, the foot in the Monomyaria (b, fig. 348)
appears rather as an appendage to the mass
of the viscera than as their defensive envelope.
The muscular fasciculi that terminate it pos-
teriorly are small; they pass through the vis-
ceral mass to be attached either to the superior
part of the central muscle, or within the in-
terior of the hooks or beaks of the shell.
Almost the whole of the Monomyaria furnished
with a foot, have a byssus also; to this rule
there are indeed a small number of exceptions,
among others the Lime.

Up to the present time the faculty of pro-
ducing a byssus is not known to belong to
any other class of animals, and it is limited
to a few only of the Conchiferous mollusks.
Among the Dimyaria the genus Byssomya may
be quoted as an example, also the members of
the family of the Mytilacea ; and, if the horny
plates of certain Arche be likened to the

Fig. 353.

CONCHIFERA.

byssus, it would also be necessary to include
this genus in the group of byssiferous Dimyaria. —
In the Monomyaria provided with a foot, the —
whole of the genera are byssiferous, with the
exception of those which attach themselves im-
mediately by their shell.

The byssus (b, fig. 353) is a bundle of horny
or silky filaments, of different degrees of fine-
ness and of different thicknesses, and flexible
in various measures, by means of which the
animal is, as it were, anchored to any solid
body sunk in the sea. The filaments, for the
most part distinct from one another, are, how-
ever, occasionally connected into a single mass
of a subcylindrical form, and terminated by a
broad expansion, which serves as the point
of attachment. This disposition is to be ob-
served in the Avicule, and leads to the belief
that the horny mass of certain Arche is a mere
modification of the byssus. In those species of
which a byssus is formed of separate filaments,
these are all seen to be detached from a com-
mon pedicle (c, fig. 353), situated at the infe-
rior base of the foot (d, fig. 353). If the
byssus be examined before any of the filaments
are torn, it is easy to perceive that these are
attached to submarine bodies by means of a
small disc-like expansion of their extremities,
of various extent according to the genus and
species (a, a, a, fig.354). Attentive examina-
tion of these filaments shews that they are of
equal thickness through their entire length, and
that they have nothing of the structure of the
hair of the higher animals.

Fig. 354.

wos

Y y))
\ ) ) pra

If the byssus and foot of a byssiferous mo
lusk be placed under a powerful lens, the I
filaments of the byssus are first seen to |
nearest to the base of the foot; and if the inf
rior edga of the foot be inspected, a fissure wil

— ee sa. —

Pa

eS fs hm es oe

CONCHIFERA. 703

be found running completely along it, at the
bottom of which a brownish and semi-corneous
filament is often to be perceived ; this is neither
more nor less than a filament of the byssus
prepared to be detached by the animal, in
order to which the animal stretches forth its
foot until it encounters the object upon which
the other fibres of the byssus are fixed ; to this
it applies the point of the foot, which then se-
cretes a small quantity of glutinous matter,
continuous with the silky filament lying along
the bottom of the furrow of which we have
spoken. When the pasty matter has acquired
sufficient consistency, and is firmly fixed to the
stone or other body at the bottom, the animal
retracts its foot, and in doing so detaches the
new fibre to the base of the pedicle. The
mode in which the filaments of the byssus are
formed, is consequently entirely different from
that in which hair or the horns of the higher
animals are evolved, and it is easily under-
stood when the intimate structure of the foot of
the byssiferous mollusks is known, when we
are aware that this organ consists in its centre
of a pretty considerable fasciculus of parallel
and longitudinal fibres. By a faculty peculiar
to the class of animals that now engages our
attention, the fibres situated at the bottom of
the groove of the foot: become horny, and are
detached in succession in the form of threads
as they become consolidated. Certain genera
are celebrated for the abundance and fineness
of the byssus; that of the Pinne, among others,
which was even known to the ancients, may be
spun into threads like silk or wool, and may be
used to manufacture tissues of an unchangeable
colour, and of great strength and durability.
With reference to form, the foot presents a
variety of interesting modifications. Some-
times it is short and truncated, as in the genus
Pholas; sometimes more elongated, but still

; : truncated at the summit,
Fig.355. Fig. 356. as in certain Razor-shells

(Solen), (a, fig. 355)
in which the edges of
the truncation are regu-
larly toothed. A few of
the acephalous mollusks
have the foot cylindrical
(a, fig. 356), as the So-
lenes ; when it presents
this form, the organ is
generally terminated by
a kind of glutinous point,
_or disc, which enables
the animal to fix itself at
different heights in the
deep cylindrical hole it
digs for itself in the
sand. The foot, which
‘is shaped like a tongue,
is named linguiform, as
in the Solen strigilatus ;
it is claviform when it
is thicker at its extremity
than at its base: it is
found of this shape in
certain other Solens. The

foot again is vermiform when it is very slender
and much elongated, as in the Loripes and
Lima. When it is thus formed, it appears
to us to be incapable of subserving motion.
In a considerable number of species the foot
is conical, as in the Cockle, (a, fig. 357);
and in this case it is generally folded into
two nearly equal portions, so that by its means

Fig. 357.

the animal can leap pretty actively. It is secu-
riform when its free edge is arched like the
cutting face of an axe, as in Petunculus,*(a,
Jig. 358). When it presents this form its edge

Fig. 358.

is generally divided into two lips, which, being
separated, present with some degree of ac-
curacy, although much contracted, the sem-
blance of the locomotive plane of certain Gas-
teropoda. When this structure occurs, the

Fig. 359.

foot is said to be bifid, as in Nucula, Trigonia.
It is said to be flattened when it is thin and
laterally depressed, as in Tellina and Donaz ;
to conclude, it is designated as bent when it
consists of two portions connected at an angle
with one another (b, fig. 359), of which the
genera Cardium, Nucula, and Trigonia present
examples. Various other modifications, of less
importance than those we have particularized,

704

also occur; these can be aptly enough alluded
to in the anatomical description.

From what has now been said it is easy to
understand the offices performed by the foot.
In the lithophagous and xilophagous Con-
chifera, the foot, reduced to its rudimen-
tary condition, is probably without any par-
ticular use, unless perhaps it be among the
Pholades, where, being in the form of a sucker,
it may enable the animal to fix itself to the
parietes of the cavity it inhabits. Among the
Conchiferous mollusks that live at large, the
chief use of the foot is to dig a furrow, into
which the animal forces itself partially, and
then advances slowly by making slight see-
saw or balancing motions, a circumstance which
has led Poli to designate the whole class of
acephala by the title of Mollusca subsilentia.
Several of these Mollusks not only make use
of the foot in the way we have just mentioned,
but also employ it as a means of executing
sudden and rapid motions, true leaps, by
which they are enabled to change their place
with great celerity. It is of course unneces-
sary to say that in those genera whose shell is
attached immediately to the bodies at the bot-
tom of the sea (Chama), the foot is of no use
as an organ of locomotion at all events. In
the byssiferous species, again, the organ, al-
though but slightly developed, is the agent in
spinning the filaments of this cable.

Nervous system.—Anatomists were long ig-
norant of the existence of a nervous system in
the Conchiferous mollusca. Poli first disco-
’ vered it in the course of his dissections, whilst
preparing subjects for the plates of his magni-
ficent work, entitled, T'estacea Utriusque Sici-
lie; but he mistook the nervous system, occa-
sionally of considerable magnitude, for one of
absorbent or lymphatic vessels, and spoke of it
under the name of /acteal vessels. In a very
interesting memoir, Mangili exposed the error
which Poli had committed, and rectified it by
assigning to the vasa luciea of his learned
countryman their true place as portions of the
nervous system.

The acephala have no brain properly so
ealled. The nervous system is symmetrical in
the Dimyaria, but loses this character in some
measure in the Monomyaria. ‘This diversity
in the nervous system, coinciding with the
number of the muscles, gives a higher value
to the character which is established on the
existence of one or two adductor muscles. In
the Dimyaria we find, on each side of the
mouth, a small ganglion above the cesophagus,
towards the base of the labial palps (1, 1,
Sig. 360). Each of these ganglions is of an
oval or sub-quadrangular shape, and the two
are connected by means of a transverse filament
(2, fig. 360) running across or over the cso-
pkagus. From the edges of the ganglions
many filaments arise, some of which on the
sides descend into the substance of the labial
pee (3, fig. 360); others anterior are distri-

uted to the edges of the mouth; and others
run to tlie lateral parts of the anterior adductor
muscle, gain the thick portion of the edge of

the nervous branches which follow the thick-—

CONCHIFERA.

Fig. 360. c
cs —
a \
ie FA =2 oe
ls AY SEA
fi if ~ -
} 1 SS
' ——
Lt 7
4
J
Shai
AN
fe 4
<= S \
* P= S2E2. il \ ——=
t a i

Nervous system of an Unio.

the mantle, and detach numerous branches.
From the posterior edges of these anterior
ganglions there is one, and occasionally there
are two nervous branches of considerable size
sent off (4, 4, fig. 360); these descend along
the body towards the base of the branchie,
concealed amidst the visceral mass, and give
off filaments in their course to the neighbour-
ing organs, first to the stomach, then to the
liver and heart, and next to the ovary and
branchiez. A considerable branch descends on
each side of the foot, and is expended upon
this organ. When the lateral filaments have
arrived opposite to the posterior adductor
muscle, they advance along its internal sur-
face, approach one another, and at their point
of junction give origin to one or two ganglions
of different sizes, but always larger than the
anterior ganglions. When the posterior gan-
glions are some way apart, a netvous filament
always connects them. It is from these pos-
terior ganglions that the nervous cords are
detached, the branches of which are distri-
buted to the whole posterior parts of the ani-
mal. Some run towards the anus, others to
the thin portion of the mantle, and a consi-
derable number to the thickened margin of the
same organ. When the lobes of the mantle
are conjoined posteriorly, and are continued
from this part by means of siphons, among —

ened edge of the mantle, one is distinguished
of larger size than the others, which termina
at the point of commissure in a small gangl

This little ganglion is not met with in th
Dimyaria w.thout a siphon; neither does”
appear in the Monomyaria. When the siphor
occur, however, a retractor muscle, peculiar t
them, is almost invariably found also, as w

have already seen. When these two part

CONCHIFERA.

exist, nervous branches are likewise discovered,
destined for them, one for each of the retractor
muscles, and one for each of the siphons.
The posterior part of the nervous system of
the Dimyaria is so considerable in comparison
with the anterior part, that some anatomists
have maintained that the title of brain should
be given to the posterior ganglions, conceiving
them to be of much greater consequence in
the organization of these animals, and of more
avail in regulating their functions than the
anterior ones.

In the Monomyaria the nervous system is in
general less perfectly developed than in the
Dimyaria. It is not quite symmetrical, and
the posterior are not larger than the anterior
ganglions. The nervous cords, too, are much
more slender, and not nearly so easy of de-
monstration as in the Dimyaria; it was not
without difficulty that we discovered them in
the common Oyster, the Peeten and the Spon-
dylus. Poli has said nothing upon the nervous
system of these genera. Our own researches
in quest of it were perfectly fruitless at first ;
but having bethought us that in the Dimyaria
the nervous cords of the labial palps were
always to be discovered without difficulty, we
sought for the same filaments in the Mono-
myaria, and were lucky enough to find them ;
these led us by-and-bye to the anterior gan-
- glions, and by degrees to the detection of the
entire nervous system. The anterior ganglions
in the Monomyaria are extremely small; they
send a principal filament to each of the palps;
a cord proceeds from them to the anterior part
of the mantle which covers the mouth ; another
runs from the ganglion of one side to that of
the other, passing above the cesophagus; and
from the posterior angle several branches are
detached to the liver, the stomach, and the
branchie. Among these there ig one, and
sometimes two, which, resting on the internal
aspect of the central muscle, bend obliquely
over its surface, and finaliy unite occasionally
to form a small posterior ganglion. This gan-
glion sends branches to the heart, to the ovary,
and to the posterior parts of the mantle. The
parallel cords traverse the thin part of the man-
tle, sometimes radiating in a slight degree, and
divide into numerous branches within its thick
margin and the tentacular ciliary processes that
fringe it. There is one among the monomyary
genera, the nervous system of which we have
not been able to study with due attention; this
is the genus Lima. From what we have seen
of it, however, it would appear that the ner-
vous system in this genus is every way as

erfectly symmetrical as in the Dimyaria. But

fore admitting this as a fact definitively, it
were necessary to have verified its accuracy at
least several times, which we have as yet had
no opportunity of doing.

- When we consider the great simplicity of
the nervous system of the acephalous mol-
lusca, we can only conceive these animals
endowed with sensibilities extremely obscure,
and with instincts extremely limited. No
especial organ of sense can be detected among

705

them, unless perhaps it be that of touch, which
appears to reside in every part of the body and
of the mantle, and probably also the sense of
taste, of which in all likelihood the maxillary
palps are the organ. The manner of existence
of these animals is in perfect accordance with
the great simplicity of their nervous system.
Many genera live attached to submarine ob-
jects, either by the shell immediately or by
means of a byssus, taking no pains to avoid or
to protect themselves from danger, and giving
no sign of existence but by opening and shut-
ting their shells: they shut them when any
foreign body comes in contact with their
mantle; and they open them to admit the
water which brings suspended in it the nutri-
tious particles which they seize upon for their
subsistence, and which is in itself necessary
for the purposes of respiration. Among the
acephalous mollusca which are not fixed in the
manner of those now mentioned, those which
have no siphon, or which have this part very
short, live at the bottom of the sea, in spots
covered with sand or mud, amidst which they
burrow by means of the foot, and support
themselves in an oblique position by resting
upon the half-open valves of their shell. The
acephalous mollusca again, which are furnished
with a siphon, almost all bury themselves more
or less deeply amid the sand or the mud of the
bottom, contenting themselves with an ascend-
ing or a descending motion, the latter sufficient
in the moment of danger to gain the limits of
their retreat, the former to enable them to
protrude the free extremity of their siphon
when they would establish the current of
water necessary to their nutrition and respi-
ration. It is easy to imagine that among ani-
mals whose functions of external relation are
so limited, the nervous system must continue
extremely simple, a fact which could in some
measure be predicated from observation of the
habits of the extensive class whose structure
and economy we are now engaged in consi-
dering.

Of the skin and its appendages.— The
mantle—The acephalous mollusca are enve-
loped by two very thin fleshy lamine, which
are seen covering or closely applied to the
whole of the inner surface of the shell; this is
the part to which the name of mantle has been
given (c, fig. 359; a, a, fig. 360). This name
has been very appropriately given to this cuta-
neous envelope, for it appears to be applied
over the back of the animal, and to be extended
over the lateral parts, to meet by its edges
along the anterior middle aspect of the body.
The mantle is composed of two parts generally
equal, or nearly equal, each of which has been
designated one of its lobes. In the natural
position of the animal, one of these lobes is in
relation with its right side, the other in relation
with its left side; they adhere intimately to the
superior and posterior part of the body; they
become free at the origin of the branchiz, and
form around the whole inferior part of the
animal a cavity of various dimensions, within
which the abdominal mass, the foot, and the

706

branchie are included. It is in this palleal
sac that the animal establishes a current of
water, destined to minister to the function of
respiration, and to carry towards the mouth the
alimentary particles with which it is fed. The
median parts of the lobes of the mantle are ex-
tremely thin and transparent, and a great
number of vessels (c, fig. 362), and a few
nervous filaments (7, 8, fig-360) are perceived
ramifying through their substance, and running
towards the anterior and inferior edges. These
edges, which extend as far as those of the shell,
are thickened, and it is at the point where the
thickening begins that the mantle adheres to the
shell by means of a great number of minute
muscles (J, /, fig.347; d, fig. 362), which leave
a linear impression upon it. The thickening of
the edges of the mantle is owing to the pre-
sence of a great quantity of muscular fibres, fre-
quently to several rows of contractile tentacular
cilia (m,m, fig. 347; e, fig. 361 & 362); and,
lastly, to that of an organ, which is the secerning
apparatus of the shell. The muscular fibres are

Contractile cilia magnified.

distributed some to the edges of the mantle,
and others to the tentacula with which it is
fringed. The whole of these parts are extremely
retractile, and are endowed with such sensi-
bility that the slightest contact is perceived, as
is evinced by their instantaneous contraction.
Zoologists have taken advantage of certain
modifications in the lobes of the mantle to
establish divisions in their methodical arrange-
ments of the conchifera. This artificial means
is sufficiently convenient, inasmuch as no
anatomical inquiries are necessary in order to
get at the distinguishing characters which these
modifications supply. __Latreille, in his ‘ Fa-
milles du Reégne Animal,’ as well as other
zoologists, have also made use of the conjunc-
tion or disunion of the lobes of the mantle to
establish the principal divisions of their classifi-
cation; but they have perhaps given too much
consequence to these characters, inasmuch as
they bear no relation to the number of the
muscles. Nevertheless, none of the Mono-
myaria has yet been found which presents
the lobes of the mantle conjoined, whilst the
Dimyaria exhibit the two modifications which
we have had occasion to mention, and which
gives an opportunity to divide them into two
grand series, the first comprising the whole of
the Dimyaria whose mantles are united, the
second all those whose mantles are open, or

CONCHIFERA.

unconnected one lobe with another. The con-
chiferous Dimyaria which exhibit the lobes o

the mantle united are modified in this r
in a remarkable manner, a circumstance which
induces us to enter somewhat in detail into
this part of the anatomy of the conchifera.

In making the series of acephalous mol-
lusca commence with those which have the
lobes of the mantle completely distinct, we
may place near them certain genera in which ~~
the branchiz, conjoined in their posterior parts,
form a kind of canal, within which the anus
Meares to terminate. This conjunction of the

ranchiz, extending as far as the edge of the
mantle, forms a kind of band towards the pos-
terior commissure; but, notwithstanding this,
it may still be said that these animals have the
lobes of the mantle altogether unconnected
(Unio) (fig. 360); in other genera which have
been held allied to this, the posterior band is
not found, and already the lobes of the mantle
appear united in the posterior part, to a very
small extent, leaving a particular perforation
for the anus. The mantle still continues open
in its circumference (Mytilus). By-and-by
neighbouring genera, and even particular spe-
cies of the same genus, instead of a single per-
foration, present two (f, g, fig. 362); the
second is destined to carry the water directly
upon the branchie. When these two perfo-
rations have the faculty of being projected
beyond the shell in the form of fleshy and con-
tractile tubes of various lengths, they have re-
ceived the special denomination of siphons;
and the term perforation has been reserved to
be applied to the holes of the mantle, which
never pass the edges of the shell.

When the two siphons begin to appear, the
lobes of the mantle still continue disjoined in a
portion of their circumference; and this opening
(b, b, fig. 356, h, fig. 362), is destined for the
passage of the foot.

Fig. 362.

In proportion as the foot is modified in its
form, in proportion as it becomes more rudi-
mentary, the two lobes of the mantle are ob- —
served in the succession of genera to become
more and more extensively united, and it hap-
pens at length that in certain genera (Mya, —
Saxicava, &e.) a very minute submedian or
anterior perforation, corresponding to the rudi-_
mentary foot, is all that remains of separation —

CONCHIFERA.

between them. It is a circumstance worthy of

remark that the siphons are observed to be-
come elongated and thickened in proportion
as the lobes of the mantle are more extensively
united. This circumstance, however, is only
true in a general way, for it would be easy to
quote many striking exceptions to it.

2. Siphons—We have already had occasion
to see the siphons commence in certain genera
by simple perforations ; they increase in length
in the succession of genera; and in a certain
number they always continue unconnected
through their entire extent (g, h, fig. 346; b,
c, fig. 355). In other genera, however, the
siphons are seen at first united towards their
base, then conjoined nearly to the middle, co-
hering almost to their ends, and finally blended
through their whole length, so as to form a
single elongated subcylindrical fleshy mass,
pierced through its entire length by the canals

_ of the two siphons, one of smaller size, situ-

ated superiorly for the anus, the other larger,
situated under the former, and destined to
transmit the water to the branchie. Whether
connected or not, the superior siphon is always
characterized as the anal, the inferior as the
branchial siphon.

The structure of the siphons is entirely mus-
cular, so that their free extremities are capable

of contracting and of being elongated to a ©

very considerable degree. They are beset
around their external orifices with a great
number of papille, (n, 0, fig. 347), occasionally
truncated at their extremities and of exquisite
sensibility. The water has to pass over these

pille before it can enter the mantle, and un-
doubtedly they apprise the animal of the pre-
sence of every foreign body that might injure
it. Ina few genera the siphons contract by
means of their component muscular fibres;
but in the greater number they have a parti-
cular retractor muscle running on each side of
the animal, and in relation, in point of mag-
nitude, &c. with the length and degree of con-
tractility possessed by the siphons (p, fig. 347).
The existence of this muscle, and consequently
of siphons, is manifested on the interior of the
shell by a posterior sinuous furrow of various
depth, and indicating upon a narrow line the
point of implantation of the retractor muscle of
the siphons.

In some of the acephalous mollusks the
siphons are too large to be received within
cover of the shell, in which case the retractor
muscle is generally small, inasmuch as it is
then of little use (Mya, Glycimeris); but in
those species in which the siphons are of mid-
dling size, or not so large as to be incapable
of entering the shell, the retractile muscle is
of considerable size and power (Tellina,
Psammobia).

3. The shell——The lobes of the mantle
appear to be the efficient parts in determining
the form of the shell, and it is by their thick
edges that this covering is in great part secreted.
The whole of the Conchiferous acephala,without
exception, are included within a bivalve shell,
the two parts of which are joined by a point in
their upper edge, to which the title of hinge

707

has been given by naturalists, and very pro-
perly, because it is in truth upon it that the
motions of the valves take place.

General structure-—When examined with
due attention, the shell is found to be composed
of two kinds of lamine very distinct from one
another (a, b, fig. 363); the one, secreted from
within outwards by the edges of the mantle,
present themselves under the form of greatly
elongated cones, the thick parts of which are
turned towards the outer surface (a, c, c,
fig. 363); the other, in parallel layers, secreted

by the central and posterior parts
. of the mantle, line the interior of
» the shell, and in many species at

7 length fill up the cavity of the
S hooks. These two layers of the
shell are frequently found in cer-
tain fossil species almost com-
pletely separated from one an-
other. At other times the inner
layer is seen to have been dissolv-
ed away, whilst the external one
continues without appearing to
have undergone any great change.
It is in the genera Chama, My-
tilus, Pinna, Spondylus, more es-
pecially that the two lamine of
which a bivalve shell is formed can
be studied to greatest advantage,
and this study is of importance
as leading to a more accurate knowledge of
certain fossil genera, in regard to the charac-
ter of which some uncertainty has always pre-
vailed, by reason of one of the constituent
portions of their shell always being found dis-
solved, as in Patillus. In some genera the ex-
ternal layer is very readily distinguished, from
having a fibrous structure (a, a, fig. 369), a
structure observed more especially in the
shells of the Pinna family and those of the
Malleacea. The two layers of the shell are in
the inverse ratio of one another in point of
thickness: the external layer, extremely thin
towards the hook, increases continually towards
the edges, whilst the inner layer, thick at the
hook, becomes thinner and thinner as it a
proaches the edges, around which it is usually
exceeded a little by the outer layer. A fact
well deserving of attention is this:—that the
muscular impressions and the whole articular
aspect of the hinge are formed in the substance
of the inner layer of the shell, and these parts,
of so much consequence, do not leave a trace
upon the external layer when this alone is pre-
served. Itis only from having neglected to study
the structure of the shell with sufficient attention
that naturalists have found themselves at a loss
to discover the true characters of certain fossil
genera, as Podopsis, Spherulites, which, in
consequence of their position in porous chalky
beds, never occur with more than the outer
layer of their shell in a good state of preser-
vation. hr

The hinge-—The part of the edge of a shell
by which the two valves are conjoined, is, as
we have already had occasion to state, deno-
minated the hinge. This part is entirely formed
by the inner layer of the shell. ‘The part of

708

the shell, of various length and thickness, upon
which the hinge occurs, is called its cardinal
edge. In the hinge two structures are appa-
rent: Ist, an elastic ligament, the position of
which is variable; 2d, projections and corres-
ate: cavities on either valve, destined un-

oubtedly to give additional strength to their
union.

1. The ligament.—The ligaments of bivalve
shells are distinguished into two kinds, accord-
ing to their structure and their position: they
are internal when they are completely hidden
by the cardinal edge of the shell; they are
external when they appear on the outside be-
yond this edge. The internal ligament is com-
posed of a great number of highly elastic
fibres, parallel to one another, and perpendi-
cular to the valves they connect. They are
secreted by a lamina of the mantle, projecting
upon the back of the animal, and penetrating
between the edges of the two shells. The
fibres of the ligament secreted when the shell
is partially open, are of too great length when
it is shut, so that when the valves are ap-
Seba aa to one another these fibres are
orcibly compressed, and their elasticity is
brought into play, by which it is only necessary
. for the animal to relax its adductor muscles in
order to have the fibres of the ligament, in-
their effort to regain their natural length, force
the valves apart from one another to a deter-
minate extent. When the ligament is external,
it rests upon the prominent parts of the cardinal
edge, parts to which the title of nymphe has
been given (a, a, fig. 365). When the ligament
is of this kind, it consists of two distinct
layers, one external, thin, and very strong,
composed of transverse fibres, which extend
from one nympha to the other, and are strongly
inserted within a groove hollowed out of the
base of each of them. The other portion of
the external ligament is of precisely the same
structure as that of internal ligiments, and is
comprised between the nymphe and the outer
layer, of which we have just made mention.
The action of this ligament is also precisely
the same: it forces the valves apart when the
animal ceases to maintain its adductor muscles
in a state of contraction.

In the extensive series of Conchiferous mol-
lusks, some modifications, as might have been
anticipated, are met with in the conformation
of the ligament, external as well as internal.
If many members of the family of the Dimy-
aria be examined, the ligament, very prominent
outwards, will be seen bearing upon nymphe
more prominent externally than the cardinal
edges, but contracting gradually under this
edge in proportion as the nymphe become
shorter, until in some species we find that,
still preserving the structure of the external
ligament, the whole of this apparatus is never-
theless entirely hidden under the superior edge
of the shell. This point attained, the external
ligament alters by insensible degrees into a
ligament completely internal; that is to say,
the exterior fibrous layer diminishes gradually,
and at length disappears entirely when the
ligament is much developed upon certain in-

CONCHIFERA.

ternal parts of the hinge. Our own opinion is,
that the ligament is internal when the nymphe,
having undergone certain modifications, have
been transferred to the interior, and have as-
sumed the form of acetabula. The ligament
is sub-internal when the nymphe, of less.
depth, still show a portion of the ligament
externally; finally the ligament is external
when the nymphe are situated towards the
upper edge of the shell. This disp!acement
of the ligament, and of the solid part which
gives it insertion, is very well seen in the
succession of the following genera: Solen,
Panopus, Thracia, Calcinella, Amphidesma,
Lutraria, Mactra, Mya, Crassatella.

In those shells in which the beaks or hooks are
of great size, and spirally turned to one side,
the ligament, in keeping pace with the growth
of the covering, bifurcates at its anterior part,
and this bifurcated part then becomes useless.
This circumstance is particulariy remarked in
the Isocardium and the Chama. The ligament
also presents a very remarkable peculiarity in
the three genera of the Arca family. The
superior surface of the hooks in these genera
(Arca, Pectunculus, Cucullea) is of greater
or less breadth, flattened, triangular, some-
times furrowed, and has a thin ligament, re-
sembling an elastic web, strongly attached
to it..

The ligament in the greater number of the
genera of the Monomyaria is situated within a
triangular groove or depression of a breadth
corresponding to its dimensions. In one fa-
mily, that, namely, of the Malleacea of La-
marck, several genera ( Perna, Crenatula ),
instead of having a single ligament, have a
regular series of fossicule, in each of which a
ligament is implanted.

Cardinal edge-—The cardinal edge presents
agreat number of modifications. Sometimes
it is simple, and of various degrees of thick-
ness, in which case the hinge is said not to be
articulated ; sometimes it presents projections
and reciprocal cavities, in which case the hinge
is said to be toothed or articulated upon the’
cardinal edge. These projections and hollows
are remarkably regular in their formation, and
every change in their appearance commonly
coincides with one of greater moment in the
organization of the animal. This remarkable
coincidence, to which only a very few exceptions
are yet known, has led conchologists to attach
great value to the characters derivable from the
hinge, and Lamarck, among others, has. grouped
several families and a great number of genera
after them. We believe, with this celebrated
naturalist, that the hinge supplies excellent
characters for the distinction both of families
and genera, but we have been led to this con-=
clusion by viewing the subject in a different
point of view from that taken by Lamarck.

Every conchologist knows the interesting —
genus denominated Pholas. In the interior of —
the valves of this genus there always exist
two kinds of large curved processes, extend
ing from the interior summit of the hoo
(a, fig. 364), and advancing nearly to
middle of the valves. According to our vie

CONCHIFERA.

Fig. 364. these appendages are the first

-)is one fact which deserves to

” be insisted on in connexion with

this genus; it is that there are

no ligaments found, and that
the cardinal edge, folded in
upon itself (rentré sur lui-
méme), is not flattened and
placed in the same manner as in
the other conchifera. Another
circumstance of equal impor-
tance to be mentioned is that
the processes, of which we have

just spoken, are buried in the
substance of the animal, and
% covered with a duplicature of
the mantle which accompanies

them as they plunge amid the
Petricola. visceral mass. Without leav-
ing the genus Pholas, the cuil-

lerons may be seen graduall
contracting in their breadths, be-
coming shorter, and approaching
© nearer and nearer to the edge.
But if other shells be examined,
which obviously form the links
of transition from the Pholada to
the Savicava, or Petricola, the
rocesses are found to turn upon the edge, to
‘ me coherent with it so as to form a salient
margin, and by their free extremity to produce
a projection (6, fig. 364). In our opinion the
toothings of the hinge of all the other bivalve
shells are produced in the same manner; but
with such modifications as rarely admit of those
relations being traced which are to our mind
obvious in those genera that have just been
particularly mentioned. With regard to the
shells of the genera in which the hinge is
complicated, of which the cardinal edge is
thickened, and the cavity of the hook partly
filled by the external layer of the shell, it is
difficult to imagine in what manner the suc-
cessive growth of the hinge has taken place,
and to make out its analogy in point of struc-
ture with that of the Petricola pholadiformis
and of the Pholada generally. To discover
this it is necessary to break a great number of
the shells, or to make various sections of the
edge, when the direction of the denticulations
with which it is furnished must be followed.
The teeth of the hinge will then be seen arising
from the summit of the hook (c, fig. 364),

Pholas.

surrounded and hidden by the matter of the
cardinal edge itself, and these arcs thus disen-
gaged will be found to present the strongest
analogy with those of the Pholada. It is from
viewing the hinge in this manner that we have
been induced to think that its structure was in
reality of sufficient importance to make it be
constantly appealed to for the distinguishing
characters of genera.
_ Naturalists have agreed to designate as the
cardinal teeth those solid projections which
_ arise on the edge of the hinge. These projec-
tions on the one valve are for the most part
accompanied with corresponding depressions

Sy parts of the cardinal teeth. There. depressions are called cardinal pits.

Sig. 365).

becoming developed, and forming a solid arc, Qias

709

on the other for their reception mutually. The
These
cavities and these projections present a great
variety of modifications which cannot be well!
understood without a long and careful study of
the conchiferous tribes generally. When the
teeth are collected under the hook, they pre-
serve the title of cardinal (b, fig. 365); when

Fig. 365.

one or two in number, and remote from the
centre of the hinge, they are named lateral
teeth. Of these lateral teeth one is an-
terior (c, fig. 365), the other posterior (d,
The anterior lateral tooth is com-
monly situated at the extremity of the lunule,
and the posterior lateral tooth at the extre-
mity of the ligament. The cardinal teeth,
properly so called, vary in number. When
there are but two, the one is anterior, the other
posterior ; when there are three or more, those
in the middle are entitled median teeth. If
the hinge be composed of a great number of
teeth, it is said to be serial (b, b, fig. 366).

Fig. 366.

Area,

710

The teeth are commonly simple and conical ;
occasionally they are flattened either lengthwise
or transversely. Ina considerable number of
species they are grooved to different depths on
their summits, and the teeth are then said to
be bifid (e, fig. 365).

There are other parts still which present
themselves upon the cardinal edge, and of
which it is important to have a sufficient know-
ledge,—namely, those destined for the implan-
tation of the ligament when it is external; to
these parts the name of nymphe is given.
These form two callosities more or less promi-
nent, which are seen along the posterior and
superior edge of the shell. When the ligament
is internal, it rests upon a cavity generally pro-
minent towards the interior of the valves, and
designated by the name of cuilleron or spoon-
shaped cavity. This cuilleron is generally
situated in the centre (c, d, fig. 367) of the

Fig. 367.

=

j

hinge ; sometimes, however, it becomes a little
oblique, elongated, narrower, and runs in the
direction of the posterior and superior edge.
When we direct our attention to the external
forms of the bivalve shells, we observe numerous
modifications, of the principal of which it is
necessary to take some notice. In a consi-
derable number of species the two valves are
alike, when the shell is said to be equivalved.
When one of the valves is larger than the other
it is of course ineguivalved ; to constitute it so
it is not necessary that the shell should be
irregular. A regular shell is that which at
liberty always presents the valves alike in all
the individuals of the species; am irregular
shell is not only inequivalved, but farther, the

CONCHIFERA.

whole of the individuals of the same spe

are not exactly of the same form, and want the

same peculiarities of external conformation

generally. The Oysters are inequivalve and irre-

gular shells ; the Corbules are inequivalve and

regular shells; the Venus and many others are

perfectly equivalved and regular ; the Placunes,

to choose a particular example, are in like ©

manner equivalved but irregular. The length

of a shell is always calculated from the summit

of the hooks to the inferior edge. All that are

of greater length than breadth are entitled

longitudinal, ( Mytilus, Pinna, &c. fig. 353) ;

and all that are of greater breadth than length

are named transversal: the breadth is estimated

by a line passing from the anterior to the

posterior extremity, and cutting the posterior

axis of the shell at a right angle, (Solen, Tel-

lina, &c. The number of transverse bivalve

shells is very great: fig. 367). If the position

of the hooks with relation to the transverse

and longitudinal lines be considered, the shell

is said to be symmetrical, when, the hooks

being in opposition, the anterior segment is

equal to the posterior, and of the same form

in consequence of this symmetry; a perfectly

symmetrical bivalve shell might in fact be

held to be composed of four similar parts ; but

this perfection of symmetry, which exists in

many Brachiopods, never appears among the

conchifera properly so called, even those

which are the most symmetrical in external

character, as certain Petuncula, fig. 358, would

be more correctly designated as swb-symme-

trical. When the hooks are inclined to one

side of the shell, and divide it into two equal

parts, it is said to be equilateral. But if the

hook be carried further forwards than back-,

wards, so that one of the sides of the shell

then becomes larger than the other, it is said to

be inequilateral. In the greater number of the

conchifera the two valves of which the shell

Consists join each other accurately around their

whole circumference, in which case the shell

is said to be shut or closed. When, on the

contrary, the two valves present a vacancy. |

between them in some part of their circum- i

ference, when they are approximated as nearly

as possible to one another, the shell is said

to be patulous. This open space is vari-

ously situated in different species, sometimes

in the anterior surface, rarely in the inferior

edge, but pretty frequently in the posterior

edge, especially in those species of the class

whose mantle is prolonged on this side into

one or two syphons. :
Surfaces of the valves.—Every bivalve shell

has two surfaces, an external surface and an

internal surface. Various parts are distin-

guished on the external surface,—the hooks,

the belly, the edges, the lunule, and the

corslet. e
External surface. 1. The hooks. — The —

protuberant opposed parts, often inclined to- —

wards the anterior side, and eer an

apex of various degrees of sharpness or b

ness, are thus. denominated. When these

hooks are very much inclined forwards, they

are styled Jateral. If they are particularly

CONCHIFERA.

ate they are said to be cordiform.
hen they are inclined towards one another,
so that their summits approximate, they are
said to be opposed. The hooks in no case in-
cline to the posterior side; but occasionally
they disappear almost entirely, and, as in the
Solens, exhibit no kind of prominence. In
other instances again they project a great way,
and form the most prominent part of the shell
(Mytilus, Pinna), in which case the hooks are
said to be terminal.

2. The belly of the shell comprises the
greatest part of the exterior surface. It is
bounded at the base of the hook, as also by
the lunule and the corslet. It is more or less
rounded or flattened according to the general
form of the shell, and we shall speak of the dif-
ferent points worthy of consideration con-
nected with it when we come to define the
various particulars of the external surface con-
sidered in a general manner.

Fig. 368 A.

pf

a, superior edge; 5, uncus; c, Innula; e, anterior
edge; f, inferior edge; g, posterior edge.

a, anterior edge; 6, inferior edge; c, posterior
edge; d, edges of the shield; /, ligament ;
f to h, nympha; h, other extremity of the liga-
ment; i, point of the uncus or hook; / ton,
lunula; J, anterior cardinal tooth; 7, median
cardinal tooth ; g, posterior cardinal tooth; m,
anterior lateral tooth; 0, anterior muscular im-
pression; p, posterior muscular impression ; 1,

- palleal impression; s, sinuosity of the palleal
impression.

7il

3. The edges. — These are indicated, pre-
serving the shell in the position which we
have mentioned ; they are anterior, posterior
inferior, and superior. The extent of these
edges is very various, and depends entirely
on the form of the shell and the position of its
hooks. Upon this particular the simple in-
spection of a collection of shells will give
much more information than we can hope to
do by the most laboured description; so that
we shall only say that the anterior edge cor-
responds to the head of the animal, the pos-
terior to its posterior extremity, the inferior to
its ventral aspect, and the superior to its back,
The edges in themselves, however, present a
few particulars which it were well to mention.
Sometimes they are thin and cutting ; very com-
monly too they are thick and continue simple.
In those species especially whose shells are
marked externally with longitudinal strie, they
are notched and toothed alternately, the pro-
jections of the one valve in almost all instances
being received into the cavities of the other.
When these projections and notches are very
fine, the shell is said to be crenate; if larger,
toothed ; when very large and few in number,
with their summits blunt, again, the edge is
undulating as in the Tridacna; on the con-
trary it is angular when the prominences con-
tinue sharp as they do in certain of the Ostree;
in the latter case the edge is also said to be
widely or deeply dentated.

4. The lunula does not occur in eve
genus of bivalve shell. It is met with, how-
ever, among the greater number of the Mono-
myaria; it is also met with among many Dy-
myaria, and is particularly conspicuous in the
Venus. It is a space comprised: on the ante-
rior surface immediately under the hooks, and
is generally circumscribed by a particular line
or depression. The lunula presents certain pe-
culiarities which it is often of consequence to
attend to, in order to distinguish certain spe-
cies otherwise apt to be confounded with one
another. Its form is various, sometimes cordi-
Jorm, a shape which almost peculiarly belongs
to inflated and subglobular species; sometimes
lanceolate, sometimes very narrow, especially
in species whose shells are flattened. The
lunula is very rarely prominent, unless it be
towards the centre. Sometimes it is super-
ficial, pretty frequently depressed, and there
are a few genera or species in which it is deeply
hollowed.

5. The corslet occupies a part of the su-.
perior and posterior edge of the shell. It is
only met with in the Dimyaria; it is not so
accurately bounded as the lunula; it is also
wanting in a great number of genera, in which
its presumed position is arbitrarily determined.
It is towards its upper part that the nymphe
are observed in those species whose ligament
is external.

In a very considerable number of Mono-
myarians the lunula and corslet are replaced
by certain projecting parts to which the name
of auricule or auricles has been given. These
occur more especially in the Pecten family—
the Pectinites of Lamarck; they are distin-

.

712

guished into anterior and posterior, and they
are frequently unequal.

If we now turn to the particulars of the
external surface of the shell of the conchi-
fera, we shall find many points worthy of
being attentively noted. fn’ a very great
number this surface is covered with a thin
and frequently deciduous lamina of a sub-
corneous and often filamentous substance, to
which the title of epidermis has been given.
This matter is secreted by the most external
edge of the mantle, but observers have not
yet stated in what manner the secretion takes
place, and what means the creature employs
to make this epidermis adhere so strongly to
its shell. The epidermis often occurs both of
considerable thickness and extent (Glycimeris,
Solemya), and thus constitutes an important
portion of the shell. In other genera the epi-
dermis appears to be wanting entirely, and in
others bears some resemblance to velvet of
thicker or thinner pile, and then consists of a
large quantity of short hair, standing erect,
and more or less closely set. In some species
these hairs become more scanty, but increase
greatly in length, as we perceive in certain
Archide and Bucarides. When it occurs in
certain species the successive growths of which
are manifested by irregular ridges, the epider-
mis is irregularly squamous. The epidermis
is insufficient to furnish any generic character
that can be depended on; for there are certain
extremely natural genera in which some species
are covered with it whilst others are entirely
naked.

The other particulars of the external surface
ef the shell are soon glanced at: they consist
of strie, ridges or ribs, and furrows, which,
according to their direction, are distinguished
into longitudinal when from the hook they run
towards the inferior margin, and transverse
when they fol:ow an opposite course, that is to
say, when they run from before backwards ;
they are oblique, again, when they follow a line
in any way inclined to the longitudinal or the
transverse. These siria, ridges, and furrows,
may cross one another, and the shell] is then
trellised. They may also severally present a
great variety of particular appearances, the de-
finitions of which may be found in the ordinary
elementary works on Conchology, but which may
all be learned much more rapidly from even a
very moderately attentive study of the shells
themselves than from any written description,
however minute and accurate.

Internal surfuce-—The inner surface of bi-
valve shells is commonly smooth and polished,
and often presents different colours which de-
pend on the secretion of that part of the man-
tle which produces the solid lamine of the
inner surface. The greater number of shells
are white within, and many of them are na-
creous or like mother-of-pearl. Mother-of-
pearl would appear to be the consequence
of a molecular arrangement of the calcareous
matter intimately united in a constant ratio
with the animal matter by the combination
of which the shell is formed. The pro-
_ portion of the two substances does not ap-

CONCHIFERA.

pear to be the same in the non-nacreous and
the nacreous shells; there are some which
afford a much larger proportion of calcareous,
and others which yield a much larger propor-
tion of animal matter when analysed than is
usual. Naturalists are now generally aware
of the experiments, an account of which is to
be found in the Philosophical Transactions,
from which it appears that the nacreous lustre
is owing to the decomposition of light by an
infinity of asperities of excessive minuteness
which beset the surface of the shell. It has,
indeed, been found possible by means of an
impression from a mother-of-pearl surface taken
in sealing-wax especially, to transfer the power
of exhibiting corresponding phenomena to the
surface of the wax.*

There is a variety of characters exhibited
by the interior of the valves which it is of con-
sequence to be familiar with. In shells which
have belonged to dimyary mollusks, two
muscular impressions of variable depth are
constantly to be found in the interior. Some-
times they are so superficial that they escape
an examination which might even be charac-
terized as minute. One of these impressions
is on the anterior side of the shell, the other
on the posterior. They are generally sub-
rotund ; sometimes, however, they are elon-
gated, which serves as an announcement that
the muscles were flattened. In some genera
these muscular impressions are of a particular
form, as may be observed in the Lucina for
example. It is a circumstance worthy of ob-
servation that the muscles of the animal shift
their place and come forward in the shell in
proportion as it grows, and it might have been
concluded, a priori, that this could not be
otherwise, when the mode of increment pecu-
liar to the class is taken into consideration.
On escaping from the ovum, a conchiferous
mollusk is already provided with its shell, of
course of very small size, and its two adductor
muscles; and the relations of these muscles to
the shell and the other internal organs are the
same as at every subsequent period. When
the animal has attained to some lines in length, _
and by the lapse of time to much larger di-
mensions, did not the muscles undergo a
gradual displacement the shell would be found
as thin at the summit as it was on escaping
from the egg, and the muscles prolonged into
the interior of the hook. Now, not only does
the shell go on increasing in thickness and the
hooks fill up, but observation shows that the —
adductor muscles always preserve the same
relations and the same proportions. To study —
in the best possible manner the successive dis- —
pisceeee) of the muscular impressions, the

est mode is to saw a fossil oyster-shell length-
wise in a line passing from the summit through
the centre of the muscular impression. rhe
impression will then be seen beginning toward

* [We have heard this point disputed. T
power which the sealing-wax had certainly gaine
In some instances of exhibiting the mother-
pearl lustre was afterwards shown to depend on t!
wax having detached a minute film from the su

face upon which it had been pressed.—ED.]

CONCHIFERA.

the summit and increasing gradually in’ its
dimensions, so as to form a long triangular
imprint, running obliquely through the thick-
ness of the shell. When, at a very early age,
the shell was extremely thin, the muscular im-
pression existed very near to the external sur-
face; but in proportion as the animal has
become older, and new layers of calcareous
matter have been successively added to the
| former, the muscular impression is found to
___ have become farther and farther removed from
_ the external surface. It is generally on the
surface of the muscular impressions, and in
_ the substance of the adductor muscles them-
selves, that those peculiar solid and highly
ate excrescences called pearls are produced.
se excrescences are engendered in a very
considerable number of genera, and it is to be
presumed that they may occasionally exist in
all; it is, however, among the Monomyaria
that pearls are most constantly formed.

Various causes have been assigned to explain
the formation of pearls. But it seems enough
to be aware in a general way of the manner in
which bivalve shells grow to understand how
pear!s are produced. Their production, it would
appear, may be assigned to some accident hap-

ing to the animal; sometimes a few grains
of sand getting between the mantle and the
shell prove nuclei for their formation, but still
more frequently they are consequences of per-
_ forations made by a species of Annelidan, to
_ the attacks of which bivalve-shelled animals
are obnoxious. In either case the animal, feel-
ing itself injured, deposits over the grain of
sand or the small orifice made by the Annel-
idan, a thin layer of nacreous matter, secreted
_ accidentally and superabundantly with re-
ference to its regular lamine of progressive
growth. In consequence of this, the shell at
the point where the grain of sand lodges or
where it is wounded acquires more than its
_ usual thickness. This thickening, from the
- mere fact of its presence, becomes a perma-
nent cause of excitement to the mantle of the
_ animal, so that this organ goes on secreting an
_ unusual quantity of calcareous matter, in con-
sequence of which there results an elevation
that increases with the age of the animal, so
much the more rapidly as the annoyance has
_been greater and more permanent. When the
mass has increased so much as to penetrate
somewhat deeply into the substance of the
organs, it is then apt to go on increasing by
depositions of nacreous matter upon one of its
extremities, by which we have pedunculated
and elongated a produced. Zoologists
have also asked how those pearls that are
found perfectly free in the interior of conchi-
ferous mollusks were formed. We shall first
_ observe that these pearls are met with more
especially in the substance of the adductor
muscles; now if it be remembered that these
muscles shift their place in proportion as the
animal prow it may readily enough be al-
lowe a pediculated pearl developed on
the surface of. the muscular impression itself,
ight be detached from its connexion with
the shell by the advance of the muscle, be-

VOL. I.

713

come free in the substance of this muscle, and
there continue to increase with more or less
rapidity. This explanation, which we advance
for the first time, appears to us sufficiently
pene peh but, before admitting it as an esta-

lished fact, it would be well to institute
some experiments in regard to the successive
changes of position undergone by the adductor
muscles of a conchiferous animal.

Fig. 369.

'
4

The mantle, as we have seen, is attached to
the shell by a determinate portion of its sur-
face. In the Dimyaria the part that is ad-
herent is not far from the thickened edge of the
mantle ; it adheres by means of the small
muscles which regulate its contractions, as well
as those of the tentaculary papille with which
it is commonly fringed. In the Monomyaria
the adhesion of the mantle is situated much
higher, and very nearly at the place where the
lobes of the mantle are detached from the
general mass of the body. From the adhe-
sion of the mantle to the shell there results a
linear impression, to which M. de Blainville
has given the name of palleal impression ; in
the Dimyaria it extends from before backwards,
from the anterior to the posterior adductor
muscular impression, following the circum-
ference of the edge. ‘This linear impression
is simple when it presents no inflexion in its
course. In a considerable number of the Di-
myaria it is observed to form a notch of dif-
ferent depths in different species, directed
towards the mantle. This notch appears to be

3A

714

produced, as we have already said, by the pro-
per retractor muscle of the siphons. |

Besides the muscular impressions of which
we have now spoken, several others of much
less importance have been particularized in the
greater number of the conchiferous mollusks.
All the species that have a foot have peculiar
muscles to move this organ, and these have
their fixed point of action on some point of
the interior of the shell. They are generally
divided into two principal fasciculi; the one
runs to be inserted within the hooks, the other
in the Dimyaria proceeds to be attached before
and above the posterior adductor muscular
impression. In the Monomyaria, the foot of
which is generally rudimentary and without
use, we observe nothing more on each side
of the body than a single small fibrous fas-
ciculus, the impression of which is found on
the inside of the hooks. In some genera of
Dimyaria, and particularly in the Unio, we
observe three and sometimes four muscular im-
pressions belonging obviously to the adductor
muscles of the valves, which are occasioned
by the anterior adductor muscle in particular
being divided into two fasciculi, often of un-
equal size, as in certain Uniones, and some-
times equal and of considerable magnitude, as
among the Iridines.

From the summary and concise view we
have taken of the principal facts in the organi-
zation of the Conchifera, very important con-
clusions may be drawn with reference to the
classification of these animals.

Taking the Conchifera, properly so called,
and looking narrowly into that which is of
most importance in their organization—the ner-
vous system, we find two principal modifica-
tions, coinciding in a very remarkable manner
with the number of the muscles. This num-
ber of the muscles, permanently proclaimed
by the impressions they leave on the shell,
presents an important character by means of
which, while we define their limits somewhat
more strictly, we feel authorized in retaining the
two grand orders of Lamarek,— the Conchi-
fera Dimyaria, and® the Conchifera Mono-
myaria. A fact of some importance, and
brought to light by the observations of Poli,
is that a small nervous ganglion exists at the
point of commissure in those acephalous mol-
lusks which have the lobes of the mantle con-
joined. This peculiarity gives new conse-
quence to the characters drawn. from the con-
joined or disunited state of the lobes of the
mantle. Unfortunately the circumstance is
not always indicated upon the shell; it is, in
fact, only obvious upon those inhabited by
siphoniferous animals; it is quite inapprecia-
ble upon those the inhabitants of which have
siphons so short as not to require a particular
retractor muscle to draw them within cover of
the shell. With regard to the other organic.
characters which furnish data available in clas-
sifying the Conchiferous mollusks, these are all
of so little permanency that they are only
useful in supplying secondary hints for the
arrangement of families and genera. Thus
neither the branchie nor the heart present any
character susceptible of generalization or of

CONCHIFERA.

contrast. Better data might perhaps be ob-
tained from the conformation of the organs of

. digestion; but these organs have hitherto been

examined in comparatively so small a number
of genera and species that they cannot be
brought forward usefully in supplying “cha-
racters for a general classification. If, as we
ourselves feel inclined to do, the hinge be
taken’as the point of starting in the Pholades,
this part may be made the means of giving
excellent characters in its principal modifica-
tions for the establishment of genera. It is,
indeed, very remarkable that we should find
the characters as indicated by the hinge
almost constantly in harmony with those af-—
forded by the rest of the organization; and
with a few exceptions, relative to several ex-
tremely natural families, that of the Unios for
example, all that is valuable in the generic cha-
racters generally may be preserved along with

the characters supplied by the hinge. Ano-
ther character which may be usefully employed

in classification is assumed from the regularity

or irregularity of the shell of the animal; in
generalizing upon this, like groups are obtained

in the two principal divisions of the Conchifera,

and the two principal divisions of the classi-
fication are referred to the simplicity or exact-
ness of the dichotomy, whilst natural groups

are preserved as much as may be in the linear
arrangement.

Method, it must ever be remembered, is an
artificial means of introducing order among a
series of observed facts, and of approximating,
according to the analogy of their organization,
the beings which nature has scattered over the
face of the earth; method is a human creation
altogether, and in this light must it be viewed.

To be all it ought, every known fact must be
included, and the greatest possible amount of
organic relationships between the individuals
of each great class must be indicated. In an
exposition of facts seriatim, and as they occur
in a book, every thing has to be arranged in
sequence, and therefore in the linear mode,
now so generally followed by naturalists. In
this way, however, it is impossible to express
the enchainment, the inosculation, so to speak,
of the different groups. To counterbalance this
inconvenience, we are of opinion that the clas-
sification ought to be made with lateral offsets,
now terminating abruptly, now divided once or
twice, sometimes inosculating variously, and
again, departing from a common trunk, dispo-
sed in one case in a right line, in another in a
curved line, and in a third in a circle. We
conceive that it is according to these new views
only that the acephalous mollusks can be pro- —
perly arranged; it is accordingly upon the
principles just announced that the following
table is constructed. . ie

Although in the present state of our know-—
ledge of these animals many important parti-
culars are still unquestionably wanting, this”
division of the molluscous tribes nevertheless
presents fewer gaps than any of the others, i-
asmuch as opportunities have occurred of ex-
amining some one or other of the animals be-
longing to the whole of the genera. = ae

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716

This tabular yiew of the classification exhibits
certain particulars, upon which we deem it
necessary to offer a few explanatory remarks.
As we said before, the series as a whole may
be regarded as a common trunk, from which
various branches spring, sometimes anastomo-
sing, sometimes ending abruptly. It is thus
that from the Clavigella we observe a lateral line
departing, formed of the genera Fistulana,
Galeomma, and those of Lamarck’s family
of Petricola. These genera descend parallel to
the common trunk of the classification, so as
to approximate in as great a degree as possible
the genus Venerupis to the genus Venus. The
genus Pandora has numerous analogies on one
side with the Corbula, but it has also many
with the members of the genus Osteodesma, on
which account it is made to depart laterally
from the Corbula, and to ascend towards the
Osteodesmata. The Lutraria are also variously
related to several genera of the Osteodesmata,
and this genus is joined to that of the Thracia
by means of the genus Anutinella, which we
place crosswise to connect the genera just men-
tioned. In the Mactracea, we pass without
any very great stride from the Lutraria to the
Mactra, from the Mactra to the Erycina
and to the Amphidesma. Farther, in order
not to interrupt this series of relation-
ships, we place upon a lateral line departing
from the Mactra the two genera Mesodesma
and Crassatella. Every naturalist knows how
great the resemblance is between the flat and
broad Solens ( Soletellina, De Blainv.) and the
Psammobie ; but we also know that the genus.
Psammobia has so many analogies with the
family of the Tellinida, that it is impossible to
detach it from this family in order to include it
within the family of the Solenacee. To avoid
interrupting the relations of this genus to those
of the Solen family, we have recourse to an
ascending line composed of the genera Svlen-
ertus, Panopea, Solen, Solemya, and Glyci-
meris, by which means we approximate, as
much as possible, these last genera to the fa-
milies Pholadia and Osteodesmata, with which
they have in fact unequivocal relationships in
point of organization. We consider the family
of the Lucinide as a lateral and truncated
branch of the Conchida, divaricating from the
genus Astarte. Withregard tothe Cyclada, we
place the genus Glaucoma of Mr. Gray laterally,
between the Cyrenas and the Venuses, so as to
establish the connexion between the two ge-
nera; whilst departing also from the genus
Cyrena we place our genus Cyrenella obliquely
in order to make it join that of Lucina,
this genus of Cyrenella being to Cyrena
and Lucina that precisely which the genus
Glaucoma is to Cyrena and Venus. To
us the family of the Chamacea is a lateral
offset from that of the Cardiacea, and although
the Etheri@ and the family of the Rudistes are
in reality among the number of those Conchife-
rous mollusca which have the lobes of the
mantle disjoined, still as they do not imme-
diately arrange themselves in any particular
part of this section, we have placed them to the
side in continuation of the family of the Cha-

CONTRACTILITY. a=

macea, but underneath them. The family of
the Ostracea we now believe to consist of the
single genus Ostrea, and we propose under the
name of Placunide a family containing the
three genera Placuna, Placunonomia, and Ano-
mia, which according to our views constitute a
descending and lateral line really intermediate
to the Conchifera and the Brachiopoda.

BIBLIOGRAPHY. — The following works and
essays may be referred to as still interesting
on the natural his of the Conchifera, Reau-
mur, De la formation et de _ Jl’accroissement
des coquilles, Acad. de Paris, An 1709 et An
1716; Ej. De la maniére dont plusieurs espéces
d’animaux de mer s’attachent au sable, aux pierres,
&c. ibid, An1711. Walch, Vom Wachsthum und
den Farben der Konchilienschaalen. Besch. der
Berlin. Naturforsch. Gesell. B. i. S. 230. Miiller,
Anmerk. ueber Walch, ibid, B. ii. S. 116. * * * *
Cuvier, Nouvelles Rech. sur les coquilles bivalves,
Société Philomath. A. 7, p. 83. Lister, Anatomy
of the Scallop, Philos. Trans. Year 1697. Ante
van der Heide, Anatome Mytuli, 12mo. Amst.
1684. Bojanus, Sendschreiben an G, Cuvier
iiber d, Athmen und Kreislaufswerkzeuge d. Zwei-
shaaligen Muscheln, 4to. Jena, 1820. Mangili,
Ricerche nuovi zootomiche sopra alcune specie di
Conchiglie Bivalvi, 8vo. Milano, 1804. Brach,
De ovis ostreorum, Misc. Ac. Nat. cur. Dec. 2,
An 8. Koehlreuter, Obs. anat. physiol. Mytili-
cygnei (Lin.) concernentes, Nov. Act. Petrop.

t. vi.
(G. P. Des Hayes.)

>, Cees | i _ —

CONTRACTILITY. — Since it has been
generally understood, that all the most striking
and conspicuous movements which take place
in living animals, depend on peculiar contrac- _
tions of certain of their solids, the circum-
stances of these contractions, the causes by
which they are excited, and the laws by which
they are regulated, have been justly regarded
as objects of the highest interest, and of fun-
damental importance, in physiology. The
term Irritability was employed by Haller and
his followers, to denote all such contractions
in living bodies, as they judged to be peculiar
to the living state; but more recent inquiries
have shewn the necessity of distinguishing
different species of these contractions; and the
more comprehensive term Contractility is now
pretty generally employed. To this the epithet
Vital, in physiological discussions, may usually
be understood as prefixed.

It is to be remembered, however, that several
of the animal textures are endowed with a pro
perty of contraction, in certain circumstances,
which is not peculiar to their living state, but
subsists as long as their structure remains unal-
tered after death; and the distinction between
the phenomena resulting from this cause, and
those which are strictly vital, has not always
been accurately observed. Thus many of the —
soft animal textures, muscles to a certain de-
gree, tendons and ligaments in a greater degree,
and arteries in a still greater degree, are ela
and liable to contractions from that cause when
stretched. The Contractilité de Tissu of Bicha'
is in most cases to be considered simply as
Elasticity, although in some cases (as when h
assigns this property as the reason of the re-
traction of the cut extremities of a living muscle

CONTRACTILITY.

or of the stiffening of limbs after death,) he
gives this name to contractions which are
strictly vital. Almost all animal substances
are liable to contraction from heat, and from
the application of various chemical agents
which affect them as astringents, to which
property Bichat gave the name of Contractilité
par racornissement ; and it is easy to perceive
that this property also, although persistent in
the perfectly dead body, and therefore inde-
giniienk of life, may give occasion to contrac~
tions which may sometimes be mistaken for
indications of the strictly vital contractility.

Confining our attention, however, to such
contractions of the solids of organized bodies,
as are exhibited by them only in their living
State, i.e. so long as they present that assem-
blage of phenomena, to which we give the
name of erie proceed to state the facts
which seem to be most important and best
ascertained, first, as to the modes in which
they are excited ; secondly, as to their pheno-
mena, and varieties; thirdly, as to the condi-
tions necessary to their manifestation; and,
lastly, as to the laws which regulate them.

I. It is universally known, that the most
striking examples of vital contractions are seen
in the effects produced by various stimuli
acting on muscles, particularly those of volun-

_ tary motion, and the heart. The essential cha-
_ Yacters of muscular fibres, their composition
nearly akin to the fibrin of the blood, their
arrangement in parallel fasciculi, which are
bound seautber’ by cellular membrane, their
soft texture, and slight elasticity are also ge-
nerally known. The change excited by sti-
muli acting on them is a contraction in the
direction of the visible fibres of the muscle,
which in the healthy state always rapidly
alternates with relaxation; and by these two
circumstances,— the excitation by stimulus,
and the quickly ensuing relaxation,—we dis-
tinguish that form of Vital Contractility, to
which the term Irritability is most correctly

lied.

Pine stimuli which produce this effect are
very various; and the experience of our own
jodies points out the obvious distinction of
these into physical and mental. Of the first
kind, air and water, especially if aided by heat,
act decidedly in. this way; but those which
have been chiefly used in experiments are, dis-
tension, especially in the case of the hollow
muscles, such as the heart or bladder,—che-
mical acrids, such as acids, alkalies, various
__ alkaline, earthy, or metallic salts,—and elec-
_ tricity or galvanism. The effect of all these
stimuli is much increased by their being sud-
denly applied.

_ It has also been long known, that many
muscles are excited to contraction by such sti-
muli, when applied to certain nerves, entering
their substance, or to certain parts of the spinal
cord or brain, even more effectually than by
lications to themselves; and likewise, that
it is only when those nerves are entire, up to
the brain, that those muscles which are natu-
) a, obedient to the mental stimulus of the

Will, ‘can be excited by voluntary efforts.

717

From these different modes of excitation of
the contractile power of muscular parts, diffe-
tent names have been given to the power
itself, as by Haller, who applied the term
Vis Tonica to the contraction from distension,
Vis Insita to the contraction from irritation of
the muscular fibres themselves, Vis Nervosa to
the contraction from irritation of a nerve, and
Vis Animalis to the contraction from volition,
acting at the brain and transmitted through a
nerve; or again by Bichat, who applied the
term Contractilité Organique Sensible to the
contractions excited by any kind of irritation,
acting on muscular fibres themselves, and the
term Contractilité Animale to those excited by
stimuli, whether mental or physical, acting on
the nerves, spinal cord, or brain. But it is
obviously more correct to distinguish the dif-
ferent varieties of the vital power according to
the phenomena, which the contracting part
presents, than according to the manner in
which the contractions are excited ; and there-
fore those terms have fallen much into disuse.
In most instances, it is the same vital power of
Irritability, as above defined, which is called
into action in these different ways,

It is only of late years, that it has been
fully ascertained, as to the excitement of vital
contractions through nerves: 1, that it is, almost
exclusively, in the case of muscles which are
naturally subject to the Will, that even physical
irritation, confined to the nerves, has power
to excite contraction; and 2, that these muscles
have nerves, or nervous filaments, from two
distinct sources, viz. from the anterior and
posterior columns of the spinal cord, and their
prolongations within the cranium; and that
it is by irritation of the first of these only,
(or almost exclusively,) that the muscular con-
tractions are excited.* From these facts, it
appears obvious, that the grand and eternal
law of separation, as Haller calls it, of the Vo-
luntary and Involuntary muscles, consists essen-
tially, not in different powers of the muscular
parts, but in different endowments of the ner-
vous filaments which enter them.

In regard to the excitation of muscular con-
traction through nerves, it is also to be ob-
served, that although the action of muscles in
obedience to the will is the most obvious and
striking example, in the living body, where
the intervention of a change in a nerve is known
to be an essential condition of the act, yet
there are many examples of movements, per-
formed by voluntary muscles, in obedience to
mental stimuli, but not to volitions,—to sensa-
tions, or other involuntary acts of mind, even
in opposition to efforts of the will. These con-
stitute a very important class of vital motions,
and are known to be equally excited through
the motor nerves of the muscles concerned in
them. Of this kind are not only the irregular
agitations of the limbs produced by tickling, or
the convulsive writhing of the body from pain,
but also, such regular and admirably precise
movements as shrinking when pain is excited

* See Mayo’s Outlines, 2d edit. p. 50 ct seq.
and Sir C. Bell, Phil. Trans. 1826.

718

on the surface, closing the eyelids when the
eyes are offended by bright light, swallowing,
breathing, coughing, sneezing, vomiting, ex-
pulsion of feces and urine, &c. consequent
on certain sensations of the fauces, lungs, air-
passages, nostrils, stomach, rectum, or blad-
der... Such muscular actions, excited by irri-
tation of distant parts, have been generally but
vaguely described as the effects of Sympathies
of one part of the living body with another.
It is well ascertained that they are effected
through the motor nerves (or certain of the
motor nerves) of the muscles concerned in
them; and their dependence on the Sensations,
and therefore on the sensitive nerves, of the
parts from the irritation of which they originate,
has been sufficiently illustrated by Haller,
Whytt, Monro, and others.*

It has also been observed, by Haller and
Whytt, but more frequently and carefully by
Legallois,t Flourens, and Mayo,t that in
many animals, (most remarkably in cold-
blooded, or young warm-blooded animals,)
even after the removal of the brain, as long
as the circulation can be maintained, move-
ments of the kind now in question go on,
or may be excited by irritation of the sur-
faces; and that if the spinal cord be divided
into several parts by transverse sections, such
movements may still be excited in the muscles
supplied from each part, by irritation of the
portion of the skin which has its nerves from
that part of the cord. These facts have (as is
believed) usually been thought to denote, that a
certain degree of Sensation remains under these
circumstances, in connection with the living
state of the spinal cord, or of portions of the
spinal cord, and medulla oblongata, indepen-
dent of the brain; and that it is still through
the intervention of sensation, that irritation
of the surface of the body excites any con-
traction of muscles. Dr. Marshall Hall has
lately described phenomena precisely of this
description, under the title of Excito-motor
phenomena, and as proofs of what he terms
the Reflex Function of the Spinal Chord §
—a power of exciting contraction in mus-
cular fibres connected with it, which he
supposes that organ to possess, equally inde-
pendently of sensation as of volition;|| and as
it seems hardly possible to be quite certain of
the existence of Sensation in the case of the
mutilated animal, this language is perhaps
philosophically correct ; but the probability of
the existence of Sensation in such circum-
stances must be allowed to be very great; and
at all events, that sensation is an essential part of

* It is obvious that such motions, excited di-
rectly by sensations, cannot be accurately distin-
guished from those voluntary actions which are
called Instinctive, as being prompted by the in-
stincts, distinct from strictly intellectual acts,
which are linked by nature with the sensations of
certain parts of the body.

+ Expériences sur le Principe de la Vie.

$ Outlines of Physiology, second edit.
and Anat. and Physiol. Comms,

Phil, Trans. 1833, p. 635.
See particularly p. 640.

p- 282,

CONTRACTILITY.

the connection between the irritation of distant
parts, and the excitement of involuntary mus-
cular contractions of voluntary muscles, for
useful purposes, in the entire and healthy
body,—may be held to be a point well esta-
blished by the observations of Haller, Whytt,
Monro, and others, on such sympatheticactions.
Accordingly, those actions, in the entire body, _
which Dr. M. Hall ascribes to the reflex func-
tion,* are the same, or similar to those, which __
have been fully treated by Dr.Whytt and others
as sympathetic actions, or actions of voluntary
muscles excited by sensations.

But Dr. Hall has fixed the attention of phy-
siologists on this class of facts, and has illus-
trated by experiments their independence of
the Brain, and dependence on the Spinal Cord
exclusively, and in this conclusion he is sup-
ape by many facts previously recorded by

e Gallois, Magendie, Flourens, and others.

It is further to be observed, that the contrac-
tions of voluntary muscles, which are supplied
by the nerves of the Symmetrical class of Sir
C. Bell, while they are excited through the one.
set of filaments comprising those nerves, are
made known to our consciousness by the others
or sensitive filaments, and constitute the im-
portant class of Muscular Sensations. Of the
movements of the strictly involuntary muscles,
the heart, stomach, and bowels, and even the
bladder, (supplied by irregular nerves,) we
have, in the perfectly healthy state, no intima-
tion, although they frequently become percepti-
ble to us in disease, or when over-excited. But
contractions of some of these involuntary mus-
cles also are pretty certainly excited by certain
Sensations, as, e.g. a certain degree of antipe-
ristaltic movement in the stomach by the feel-
ing of nausea, and a certain movement of the
pharynx and esophagus by the sensations in
the fauces, which prompt the act of deglutition ;
and in such cases, although not attended with
consciousness, they are in all probability excited
through the nerves of these muscular parts.
Accordingly, the pharynx and esophagus have
been observed by Mr. Mayo, and the stomach
by Breschet, Milne Edwards, and others, to
be exceptions to the general rule of involun
muscles being inexcitable by irritation of their
nerves. .

The old distinction of muscles into Volun-
tary, Involuntary, and Mixed, is very deficient
in precision, so far as the last classis concerned.
The true distinction is, of muscular contrac-
tions, into those excited in the natural state by —
Mental Stimuli, and through the intervention
of Nerves (qui soli in corpore mentis sunt mi
nistri)—and those excited by Physical Stim
acting on the muscles themselves, whereas the
intervention of nerves is a theory, not an esta-
blished fact. The first class admits obvio
from what has been stated, of a division
movements excited by the Will, which depen
on the Brain, and movements excited by invo-
luntary mental acts, especially by Sensatio
which depend only on the Spinal Cord a
medulla oblongata. The Will acts only

-
il,

* P. 653 et seq.

-Tauscles likewise, but

net ee in dS hi bP miack Ap aad as

e tA PALO eee

CONTRACTILITY. 719

muscles provided with sensitive nerves, by
which the mind is informed of the contractions,
and so enabled to regulate or guide them. The
Sensations act chiefly on this description of
rtly also on muscles
the nerves of which give no such distinct inti-
mation of their contractions, and which are
uniformly and strictly involuntary; and the

_chief excitants of this last class of muscles in

the Animal Economy are physical stimuli, ap-
oe themselves and to their lining mem-
es.

II. In regard to the vital power or property
of Irritability, as exhibited in any of these ways,
the following facts demand particular notice.

1. The minutest fibres, of which the mus-
cles, exhibiting this property, consist, or what
have been called by some authors the primary
Jilaments of muscular fibres, appear under the
microscope to consist of rows of globules, or
at least to be marked by transverse strie, at
equal distances.

2. When contraction takes place, these fila-

_ Ments, or rows of globules, are thrown into a

zigzag form; the angles being always at the
same points on each contraction, and being
generally obtuse, rarely and only on occasion
of very forcible contraction, acute.* At the
points where these angles are formed, the fila-
‘Ments are crossed, according to the observa-
tion of Prevost and Dumas, by nervous fibrils;
but it is important to remember, that this last
observation has been made only on muscles
of voluntary motion, and on them only in
cold-blooded animals, where they are somewhat
translucent.

3. According to the best observations, not
made on entire limbs or even entire muscles,
which involve various fallacies, but on small
= of muscles, removed from living

dies, it appears that no alteration of the
bulk of the filaments attends this alteration of
their form, so that neither the size nor distance
of the particles or globules appears to be
changed, but merely their position in regard
to one another.+
_ 4. When by any stimulus, applied to mus-
cular fibres, the filaments directly stimulated
are thrown into action, the contractions very
generally and rapidly extend to many others
in their neighbourhood, frequently even to the
whole muscle of which they form a part; but
the contractions of single fibres appear to be
of short duration, and the more enduring
efforts to be made by many short successive
contractions and relaxations or vibrations of
the individual fibres.

From these facts it would appear, that each
exertion of this property of Irritability essen-
tially consists in a greatly increased attraction
among the particles or globules constituting

_* This appearance, with slight variations, has
been repeatedly seen, both in warm-blooded and
cold-blooded animals, in the lower classes and
even in the infusory animals, under the micro-
+t See Prevost and Dumas, in Journal de Phy-
siologie, tom. iii.; and Mayo’s Outlines.

the muscular fibres, and alteration of the di-
rection in which this attraction acts,—rapidly
communicated from one particle to another,
both along the same fibre, and among adjacent
fibres,—and rapidly succeeded by repulsion,
or return to the previous state of the cohesive
attraction existing among these particles.

When a muscular mass, consisting of many
such fibres, is thrown into this kind of action,
it is easy to understand that its breadth and
thickness, and its rigidity or resistance to com-
pression will be increased ; that its extremities
will be approximated ; and that if it be dis-
posed around a cavity, containing a fluid and
provided with an outlet, that fluid will be
expelled. It is by such contractions, that all
the more conspicuous movements, even of the
organic life, of the higher animals, are per-
formed, and that their locomotive and vocal
powers are exerted; and it is worth while to
pause for a moment to consider the almost in-
conceivable amount of moving power, and ra-
pidity of motion, which various facts indicate
in muscles thus contracting, whether under the
influence of the will, or from other stimuli.

It seems well ascertained that the contrac-
tions of the left ventricle of the human heart,
in its ordinary unexcited state, are sufficient to
expel its fluid contents, in free space, a dis-
tance of 73 feet, and to balance a weight of
above 50 lbs.; and this power is exerted regu-
larly more than once in every second, and
often, even independently of disease, twice in
every second, during the whole of human life.
The ordinary action of the left ventricle of the
Whale’s heart suffices to expel, according to
Dr. Hunter’s statement, at each pulsation,
above ten gallons of blood, with a great velo-
city, through a tube of a foot in diameter.

Two instances given by Haller, and quite
within the limits of ordinary experience, suf-
ficiently exemplify the great power occasion-
ally exerted by voluntary muscles; and which
will appear the more extraordinary when it is
remembered, that the direction of muscular
fibres, as regards the line in which they are to
act,—the points of their insertion into the
bones they are to move,—and the line in
which they act, as regards the motion which
they give to these bones,—are all, very ge-
nerally, such as to render their action dis-
advantageous, and requite a greater amount
of moving power than might otherwise have
been necessary. The instances recorded are,
the case of a man, who could raise a weight
of 300 lbs. by the action of the elevator mus-
cles of his jaw; and that of a slender girl,
afflicted with tetanic spasm, in whom the ex-
tensor muscles of the back, in the state of
tonic contraction or opisthotonos, resisted a
weight of above 800 lbs., laid on the abdomen
with the absurd intention of straightening the
body. In some of the lowest classes of ani-
mals the intensity of the muscular power ap-

ears to be greater than in any of the largest.
Thus, a flea has been known to leap sixty times
its own length, and to move as many times
its own weight. -

720

Again, the rapidity of the changes of po-
sition of the component particles of muscular
fibres may be estimated, although it can
hardly be conceived, from various well-known
facts. The pulsations of the heart can some-
times be distinctly numbered in children at
more than 200 in the minute; and as each
pulsation of the ventricles occupies only one-
third of the time from the commencement of
one pulsation to the commencement of the
next, this implies that each contraction takes
place in gijth part of a minute, or that ten
times in each second, for many hours toge-
ther, the whole of the convoluted muscular
fibres of the ventricles must be thrown into
folds, and again smoothed out. Again, it is
certain that by the movements of the tongue
and other organs of speech, 1500 letters can
be distinctly pronounced by some persons in
a minute. Each of these distinguishable
sounds must require a separate contraction of
muscular fibres; and the production and ces-
sation of each of these sounds must imply,
that each separate contraction must be followed
by a relaxation of equal length. Each con-
traction must, therefore, have been effected in
goooth part of a minute, or in the 50th part of a
second. Haller calculated that in the limbs
of a dog at full speed, muscular contractions
must take place in less than the 200th part of
a second, for at least many minutes in suc-
cession.*

But the property of Irritability, which acts
throughout so great a portion of the animal
creation, as a-moving power of this extra-
ordinary efficiency, is not the only contractile
power, which certain organic textures possess,
or which the conditions of their existence re-
quire them to exert during the living state.
Even in muscular fibres themselves, in certain
organs, and still more in other textures of
animal bodies, contractions are ofteu observed,
peculiar to the living state, but differing essen-
tially from those which come under the defi-
nition of Irritability already given.

In all the different tribes of animals, indeed,
differences in the contractile power of the diffe-
rent living solids may be observed, exactly cor-
responding to their circumstances and wants.
The slow and languid movements of the bodies
of most of the Zoophyta, and the rapid vibra-
tions of the Ciliz with which parts of many
of these animals (particularly of the order
Infusoria) are provided, are examples, even
in the lowest class, of the great variety of
moving powers, with which the living solids
of different animals are endowed.

In the human body, and analogous animals,
it is obvious that the contractile power exerted
by the stomach and intestines in performing
their peristaltic movements, although of the
same general characters as that of the heart,—
the contraction of each portion of the tube
being followed by a relaxation of that portion
and a contraction of the portion next in ad-
vance,—is yet materially different; both con-

* See Haller’s Elem. Phys. tom. iv. p. 48).

CONTRACTILITY.

traction and relaxation in the peristaltic move-
ment being of longer and less definite du-
ration, and of more variable extent. In the
bladder and in the uterus, in the healthy state,
we see contractions excited by peculiar stimuli,
and repeatedly recurring as the actions de-
pendent on them proceed, but not alternating —
with any obvious elongation of the fibres, and
terminating in a much greater and more per=
manent shortening of the contracting fibres,
than is observed in other muscular organs.
Again, in the state of any voluntary muscle,
when the distance of its extremities is per-
manently shortened (as by an ill-united frac-
ture), in that of the sphincter muscles, or of an
artery when emptied of blood, we see a
permanent contraction, requiring no stimulus
to excite it, shewing itself whenever a dis- ;
tending or elongating power is withdrawn, and
relaxing only at the close of life. The nume-
rous experiments of Dr. Parry on the condition |
of arteries immediately after death (contained |
in his Treatise on the Arterial Pulse) afford the
most precise information that we have as to
this last property. .
From such facts it appears obvious that
three distinct modes of contraction, all strictly
vital, may be observed in different textures of
the body, or even in the same texture under
different circumstances: first, that already con-
sidered, to which the term Irritability is strictly
applied, and which is best exemplified in the
actions of the voluntary muscles and the heart ;
secondly, that which may be termed simple
Contractility, where contraction is induced by
a stimulus, but takes place more slowly, and
is nearly or quite permanent; and, thirdly, ‘
that which has been accurately described by
Dr. Parry and others under the title of Toni-
city, which requires no stimulus to call itinto
action, but takes effect whenever a distending 7
power is withdrawn, and continues until
life is extinguished. The second of these
forms is seen, not only in the bladder and
uterus, but in the arteries under certain irri-
tations, perhaps in other textures, and pro-
bably also (from certain stimuli) in the fibrin
of the blood during coagulation.* The last
is clearly, as Dr. Parry’s experiments have
shewn, the chief vital endowment of arteries ;
and notwithstanding the doubts expressed on
the subject by Dr. Bostock, several facts may
be stated to show, that it is also an endow-
ment of all muscular fibres. Thus, besides
the permanent retraction, already noticed, of
the fibres of a muscle the fixed extremities of
which are approximated,—the retraction of the
cut ends of a muscle divided during life,—the —
state of habitual preponderance of the flexor
muscles of the body and limbs (which are t
stronger) over the extensors during sleep,
the stiffening or “ roideur cadaverique ’ Le
muscles after death,—seem to be clear indica-
tions of a tendency to contraction answeri

* SeePrater’sExperimental Inquiries in Che ni -
Physiology.
+ See Richerand’s Physiology.

CONTRACTILITY.

to the definition of Tonicity, not of Irritability.
This last phenomenon, as it disappears before
putrefaction begins, and as it is variously in-
fluenced by causes affecting vital action, is
allowed to be a last exertion of vital power.

There are evidently slighter modifications or
varieties of the powers which we have thus
distinguished ; but the distinctions now stated
seem to be those which are sufficiently marked
to demand separate names. Besides the mus-
cular texture, some of the membranes, espe-
cially the skin, appear to be endowed with a
‘certain degree of vital contractile power, al-
though not with true Irritability. It is remark-
able, that the greatest degree of contraction
seen in muscular fibres, is in those which pos-
sess the property of simple Contractility rather
than Irritability, viz. in the bladder and uterus
more than in the intestines, and in these more
than the heart.

III. As to the conditions, necessary to the
maintenance of the contractile powers of living
parts, it is in the first place obvious, that they
are always dependent on the maintenance of
the organization of these parts themselves.
When the muscles waste, as from rheumatic
inflammation, or from the poison of lead, as in
colica pictonum, or when their texture is gra-
dually altered, as by inflammation or in cer-
fain organic diseases occasionally affecting
them, or more rapidly relaxed and injured by
over-distension, they lose their contractile
power more or less completely; and their
power is likewise gradually diminished in old
age, as their texture partakes of the gradually
increasing rigidity.

Like all other vital actions, the contractions
of moving parts are more immediately depen-
dent on the maintenance of a certain tempe-
rature, varying in the different tribes of ani-
mals,—in all the warm-blooded (in the state
of activity) probably confined within the de-
grees of 60 and 120 of Fahrenheit. They
are dependent also on the regular supply of
arterial Blood. The experiments of Stenon
and others have shewn, that the power of
muscles is rapidly extinguished when the ar-
teries supplying them are tied. It has gene-
rally been supposed, since the time of Bichat,
that venous blood, when it penetrates muscular
fibres, is equally or even more rapidly noxious
to them, than the denial of the supply of
arterial blood; but the experiments of Dr.Kay*
have shewn, that the contractile power of mus-
cles, when failing from this latter cause, may
be restored by the influx of venous blood, al-
though in a less degree than by arterial,—
and Dr. Marshall Hall has observed, that in
hybernating animals whose respiration is sus-
pended, the flow of venous blood through all
the textures continues, and keeps up a certain
degree of muscular power ; so that the venous
blood can only be regarded as less powerful in
maintaining the irritability of muscles than
arterial blood (probably because it is incapable

* Edin. Med. and Surg. Journal, vol. xxviii.
and Treatise on ‘ syhyxia, ch. tii.

721

of affording them nourishment), not as posi-
tively deleterious to them. The act of healthy
Nutrition, by arterial blood, is therefore the
main condition of the vital power of muscles,
as of all other living solids. And it is im-
portant to remember that this vivifying in-
fluence of the living blood on the solids is
evidently reciprocal; for when any of the
vessels containing blood lose their vitality, as
from injury, the blood then coagulates, as if
drawn from the body.

There is a remarkable difference which has
been long observed, in the different classes of
animals, aud even in the different states of the
same animals, as to the consumption of oxygen
by the blood on one hand, and the indications
of muscular power on the other. The activity
of muscular power (as indicated by the rapi-
dity of the circulation and the energy of vo-
luntary muscular exertions) appears to be, in
general, in direct proportion to the amount
of action between the air and the blood, being
greatest in birds, greater in the mammalia than
in reptiles or fishes; and greater in insects,
where air is freely admitted into the interior
of the body, and applied to the blood, than in
the Zoophyta, or even the Mollusca, where
there is less exposure of the blood to the air;
and again, being greater in perfect animals
than in eggs or pupe, and greater in animals
in a state of activity than in those in a state
of torpor or hybernation. But on the other
hand, the endurance of the muscular power,
or tenacity of life, in whatever manner the
vital principle is depressed or extinguished,
is generally in the inverse ratio of the activity
of muscular contractions, and of the amount
of mutual action between the air and the blood.
Thus the tenacity of life in reptiles and fishes
is well known to be greater than in mammalia
or birds,—in some of the lower classes, par-
ticularly the infusory animalcules, much greater
than in any of the higher; in very young ani-
mals greater than in adults; and in hyberna-
ting animals, in eggs, and pupe, greater than
in any perfect animals.

Dr. Marshall Hall has observed, that in
some of the lower classes of animals, such as
Reptiles, the degree of muscular contraction
induced by stimuli, as well as its duration,
is greater than in the warm-blooded animals ;
and he has hence been led to lay down as a
general principle the reverse of what has com-
monly been stated, viz. that the Irritability of
muscular fibres is inversely as the quantity of
Respiration. But this proposition seems to
be too generally, if not incorrectly, expressed.
It seems an unnecessary innovation in language,
to assert that the irritability of muscular fibres
is inversely as the activity of muscular con-
tractions, or that the irritability in insects,
where the blood is fully exposed to the air,
is less than in the Zoophyta, where there is
much less provision for respiration. In fact,
the vital powers of contractile parts vary so
much in different organs, even of the same
animal, that it may be doubted whether any
other general proposition can be laid down as

722
to its connexion with respiration, than that of
the greater activity of muscular action, on the
whole, in those animals where there is much
exposure of the blood to the air, and the
greater endurance or tenacity of life where there
is little.

The question, how far the Nervous System
furnishes one of the conditions necessary to
the maintenance of the contractile power of
muscles, has long engaged the attention of
physiologists, and been the occasion of much
erroneous medical theory; but in the present
state of the science, need not occupy much of
our attention.

The doctrine of Cullen and many other
systematic writers, that the muscles derive re-
gular supplies of Irritability or vital power,
through the nerves, from the larger masses of
the nervous system, seems to be now pretty
generally abandoned, although the terms Ner-
vous Influence or Energy are still suffered to
retain, in the language of many medical
writers, a vague and indefinite meaning,
derived from that apparently erroneous theory.
When we remember, that after the nerves
of a muscle are cut, the muscle continues
irritable under stimuli applied to itself, or to
the portions of nerves below the section,
as long as it retains its organization unim-
paired,—that section of the nerves leading to
the heart has in very numerous experiments
been found to produce little or no eflect on its
movements,—that these movements continue
for hours after the head has been cut off, or
even (as was first shewn by Dr.Wilson Philip)
after both brain and spinal cord have been
removed from the body, provided that the flow
of the blood through the lungs is maintained
by means of the artificial respiration,—that in
hybernating animals (as Dr. M. Hall* has
ascertained) when respiration is at a stand,
the regular movements of the heart may con-
tinue for nine hours after the gradual but com-
plete destruction of the whole brain and spinal
cord,—and that there are many instances on
record, of the human fetus having come to a
full size (implying long-continued and regular

action of the heart), where neither brain nor:

spinal cord existed,;—it seems impossible to
maintain the purely hypothetical proposition,
that the irritability of muscles is dependent
on an influence or energy continually flowing
to them from the brain or spinal cord;{ and

* Philosophical Transactions, 1832

+ See Brachet’s Recherches sur le Systéme Ner-
veaux, p. 36 & seq.

¢ Mr. J. W. Earle, in a ‘* New Exposition of the
Functions of the Nerves,” has attempted to revive
this theory. He trusts chiefly to an experiment,
in which the irritability of muscles, exhausted by
repeated irritation, was mot recovered after their
nerves had beencut. But this experiment is incon-
clusive, because the muscles had become inflamed
and disorganized.—(See p. 70 and 71 of his work. )
This experiment has been lately repeated in Edin-
burgh, with precautions to prevent the inflam-
mation of the muscles, and the result was the
reverse of that obtained by Mr. Earle.—See Trans.
actions of British Association, 1834,

CONTRACTILITY.

the only question that can remain is, whether

the irritation of muscles is always effected

through the medium of nerves, i. e. whether
every stimulus which excites contraction in a
muscle first acts on some of the nervous
fibrils which enter it, and by exciting them
throws the muscular fibres into action. An ex-—
periment of Brachet* has been thought to
furnish evidence of the dependence of the
heart’s actions on the cardiac plexus of nerves,
but is so liable to fallacy, and so much op-
posed to the experience of others, on the effect
of injuries of the cardiac nerves, that the in-
ference seems to have been generally dis-
trusted.

Without presuming to decide absolutely on
a question which still divides the opinions of
physiologists, and without entering on various
arguments which have been stated-as furnishing
probable evidence either on the one side or the
other, we may observe,—1. That the safe
logical rule in such cases, is “ Affirmantibus
incumbit probatio ;” and therefore it does not
appear philosophical to teach, that the con-
traction of all muscles, on stimuli being ap-
plied to themselves, is owing to the inter-
vention of nerves, until that intervention be
proved. 2. That if the contraction of all
muscles were excited through nerves, we might
expect to find all muscles supplied with nerves,
the mechanical irritation of which, in the li-
ving or newly killed animal, should excite
that contraction. But it has been already
observed, that in the case of the involuntary
muscles, physical irritation of the nerves en-
tering them (if strictly confined to the nerves)
has very generally been found quite ineffectual
for that purpose. This seems pretty clearly to
indicate, that the power of exciting muscular
fibres to contraction is an endowment peculiar
to the nerves of the voluntary muscles, or at
least enjoyed by them in a much greater de-
gree than by others, and designed, not to
render these muscles irritable, but merely to ;
subject their irritability to the dominion of the :
Will.

The observation of Fontana on this subject, ,
made as early as 1775, and in perfect accord- P
ance with the statements of Haller previously, ,
and of many other physiologists subsequently, ‘
may still be quoted as more conclusive than
any other which has since been brought for-
ward. ‘ If you open the chest of an animal,
(a cold-blooded one answers best for the ex-
periment) and stimulate as you please the
nerves going to the heart, that muscle will
neither accelerate its. movements if it be
moving, nor resume them if it be at rest,—
even although it be prone to immediate con- —
traction on its own fibres being touched. The
nerves of the heart, therefore, are in no sense —
the organs of the movement of this muscle, as —
they are of other muscles. This experiment is
certain, and the inference direct. It would be
a contradiction to assert that the movements of
the heart take place through the intervention of

* Loc. cit. p. 125.

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CONTRACTILITY. 723

nerves, when experiment shews that nerves
cannot excite these movements.”

IV. In regard to the laws, by which the
vital powers of contractile parts may be regu-
lated, we have probably much to learn; but
three sets of facts have been observed, which
may at present be regarded as general laws in
this de 1ent of physiology.

1. Notwithstanding what has been said of
the contractility of muscles being independent
of any influence continually flowing to them
from the brain or spinal cord, it is well ascer-
tained that in a living and entire animal, where
all the functions of the body are, for wise and
important purposes, made liable to change,
from changes in the nervous system, the con-
tractile power of various moving parts is sub-
ject to increase or diminution from physical
causes acting in these larger masses of the ner-
vous system, just as they are from various acts
and affections of Mind, the effects of which
may be said to be imitated by those physical
causes. Thus in the experiments of Le Gallois,
of Dr. Wilson Philip, of Flourens, and others,
suddenly crushing any large portion, either of
the brain or spinal cord, has been found uni-
formly to depress or even extinguish the power
of the heart ; the well-known fatal effect often ob-
served from sudden violent injury of the epi-
gastrium in the human body, has been ascribed
with probability to the injury of the great semi-
lunar ganglion; and the depression of the
heart’s action which attends Concussion, and
which is the immediate cause of death in the
most quickly fatal cases of that kind, is also
generally regarded as an impression, made ori-
ginally on the nervous system, and immediately
transmitted to the heart. On the other hand,
slighter and more continued physical irritations
of the nervous system appeared in many expe-
riments, especially of Dr. Wilson Philip, to
augment the irritability of the heart. It is true
that, in all these cases, some have supposed the
effects of the violence to be on the organs of
circulation directly, and not through the inter-
vention of the nerves; but when it is remem-
bered, that some of those injuries, which are
the most rapidly fatal to the heart’s actions,
(such as the pushing of a probe along the

Spinal canal,) do not necessarily imply any

great violence to the body at large; and further,
that precisely similar effects on the heart’s ac-
tion (both increase and diminution) often result
from mental emotions and passions, which cer-

tainly act first on the nervous system, the ac-

count which we give of the mode of action of

these causes appears to be sufficiently con-

firmed.

One cause, acting primarily on the nervous

‘system, which seems to have a peculiar de-

pressing effect on the heart’s action, is, sudden re-
moval of the pressure to which the brain had
previously been subjected. The effect of this
on the heart has been repeatedly seen in surgi-
cal operations ; and this seems to be an essen-
tial part of the pathology of several cases of
Syncope, particularly of that which results,
either from bloodletting in the erect posture,
or from tapping in ascites.

Itis very remarkable that the heart, which
is so strictly an involuntary muscle, and so
little liable to excitation by stimuli applied
to its nerves, is much more liable than the
voluntary muscles both to sudden increase
and to diminution, or even total loss, of vital
power from such causes as we have now
considered. But a little reflection will shew,
that the direct stimulation of a muscle, and the
increase or diminution of its irritability, are
perfectly distinct cases. And we may approxi-
mate, at least, to an explanation of the peculiar
liability of the heart (and probably of other
involuntary muscles) to the influence of such
causes acting through the nervous system, as
augment or depress the vital power, when we
remember two facts: 1. that the causes which
act in this way are very generally such as are
applied to large portions of the brain or spinal
cord ;* and 2. that the arrangements of the
ganglionic nerves are such as to place the heart
and other organs supplied from the ganglia, in
connexion with the whole extent of the cerebro-
spinal axis, and hardly with any individual part
of it more than another.

2. There are various external agents, by the
application of which the vital power of con-
tractile parts, and especially of the heart,—the
main agent in the circulation,—may be altered
or even destroyed. It is increased, not only
by moderate increase of the Temperature in
which living parts are kept, and of the quantity
of arterial blood sent to them, but also by Elec-
tricity applied in a low degree of intensity, and
by various articles of diet and medicinal agents,
such as the various preparations of Alcohol ;
and it is diminished, or even suddenly extin-
guished often by the same agents applied in
excess, (as in the case of Lightning when most
rapidly fatal,) and still more remarkably by
certain Poisons, suchasthe upas antiar, tobacco,
digitalis, arsenic, and hydrocyanic acid. It is
still doubtful through what medium these poi-
sons act on the vital power of the heart; but it
is certain that the effect which they produce on
that power is the immediate cause of the death
resulting from them.t+

In cases of the most sudden death produced
by such causes acting in the utmost inten-
sity, the contractile power in the voluntary
muscles, as well as in the heart, has been found
to be very much diminished or even nearly ex-
tinguished ; and it is very important to observe,
that in such cases the property of coagulation
in the blood is likewise lost; which seems
clearly to indicate (what various other facts
confirm) that this change in the blood is de-
pendent on the existence in that fluid of a
certain degree of the same vital properties, to
which, we give the name of Contractility as ex-
isting in the solids. ‘

3. The contractile power of living parts is
liable to much alteration from the degree in

* See Dr. Wilson Philip’s Experimental Inqui-
ries, &c. ch. ii. and iv. ;

+ The terms Stimulant and Sedative are applied
most correctly to those agents which thus exalt or
depress the vital actions of the circulating system.

724

which it is itself exercised. The immediate
effect of frequently repeated stimulation of a
voluntary muscle, wh by physical or mental
stimuli, in a living or newly killed animal, is
gradual diminution or ultimate extinction, or
what is usually called Exhaustion of its Irn-
tability; which is gradually restored when the
stimulation is discontinued and the muscle is
at rest.

But the theoretical conclusions which have
been drawn from this fact have greatly exceeded
the legitimate inferences. It is by no means
clear that such increased action of involuntary
muscles, as results from causes of the kinds
just mentioned, which exalt or increase their
contractile power, is necessarily followed by
any corresponding depression. On the con-
trary, in the case of violent exercise, In many
instances of mental agitation and excitement,
and in the course of certain febrile and inflam-
matory diseases, we see the heart’s action
greatly and permanently increased, without
evidence of any subsequent loss of power which
can reasonably be ascribed merely to the cir-
cumstance of increased action.

It is true that the effect of many stimulating
substances, such as alcohol, is first to excite,
and after atime to weaken or depress, the actions
of the heart and circulating system; but as we
know that an equal or greater degree of excite-
ment from exercise, from exciting passions of
mind, or from inflammatory disease, may exist
without producing any such subsequent de-
pression, we ought to regard the loss of power
which follows the excessive use of such sub-
stances, as an ulterior effect of these substances
themselves, rather than as the result of the mere
circumstance of previous increased action.*
Although, therefore, we consider all exertions
of the irritability of muscles as necessarily im-
plying intervals of relaxation, and are aware of
the exhaustion of irritability by excessive sti-
mulation, yet we do not see that the operation
of those agents which augment the vital power,
particularly of the involuntary muscles, is ne-
cessarily followed by a corresponding loss of
power.

Further, it has been often alleged that the
vital power of Irritability is not only expended
or exhausted by excessive action, but likewise
increased or accumulated by rest. But there is
no evidence whatever that rest does more
than merely restore the power that had been
lost by previous exertion. A muscle or set of
muscles which has been weakened by excessive
excitement, and regained its power by rest,
may remain quiescent for an indefinite time
thereafter, and will not only not continue to
gain power, but will gradually lose, after a
time, that which it had previously possessed.
The idea of the accumulation of Irritability by
long-continued inaction has been thought to be
supported by the fact, that the stimulating
effect of Heat on all vital action, is greatest
when it is applied after long-continued Cold.
But this seems manifestly to be owing to the

_ * See Gregory’s Conspectus, art. De Remediis
Stimulantibus.

CRANIUM.

principle that the stimulating effect of heat on:
vital action is proportioned, not merely to the
temperature that may be applied, but chiefly
to the degree of change of temperature under-
gone in a given time; of which point
illustrations might be given, and which neces-
sarily implies that the effect of Heat must be |
much increased by its being applied after Cold. .
Another law, which may be deduced from
observation of repeated exertion of living con-
tractile , is of great importance both in
physiology and pathology; viz. that the udti-
mate effect of such repeated exertion, with
sufficient intervals of repose, is to augment both
the bulk and strength of muscular fibres, and
facilitate the subsequent excitation of vital
action, whether in voluntary or involun
muscles. This is seen in the state of hyper-
trophy of the muscular fibres of the arms of
labourers, of the legs of dancers,—of the heart,
in those who have disease of the valves of the
aorta,—of the bladder, in those who have
disease of the prostate gland or stricture of the
urethra ; and is in fact only a part of a more
general law,—that the habitual exertion (within
limits consistent with health) of all vital
powers, is naturally attended with an increased
flow of blood to the organs exerting those
powers, and with an increase of their nutrition.
And the counterpart of this is seen in the ve
slow and gradual, but ultimately extreme dimi-
nution, not only of the vital properties, but of
the bulk and characteristic appearance, of mus-
cular parts which have been, from any cause,
kept very long in a state of absolute inaction.
According to the observation of Andral, the
structure of muscles may in these circum-
stances be so altered, that they become ulti-
mately hardly distinguishable from cellular
texture. The act of Nutrition, and therefore the
organization of muscular fibres, as well as of ’
other living parts, is manifestly intended by | —
nature to be, in a certain degree, dependent on
the exertion of their own vital power ; and one
effect of that exercise of vital power is to
solicit or attract the living fluid to the part
concerned in it, in a manner which the re-
searches of physiologists have not yet satisfac-

torily elucidated.
( W. P. Alison.)

CRANIUM (in anatomy) Gr. xgaviov; Fr.
Crane; Germ. Hirnschadel; Ital. Cranio.

The cranium is the protective investment of
the brain, on which it is moulded, and the
form of which, in warm-blooded animals, it
represents. It also incloses and protects the
organ of hearing.

In cold-blooded animals there is not this
adjustment of the surfaces of the brain and its _
case; but, although in them the parietes of the
cranium are expanded beyond the limits of the
brain,* the principle of formation is neverthe

=

i
= , hai

* Thus, according to Desmoulins the area of a
vertical section of the brain in the European tor-
toise is nearly one-third less than the area of
cranial cavity ; and in Fishes, whether osseous
cartilaginous, the disproportion is constantly s
greater.—ED. ree

CRANIUM.

less the same; and a glance at the several
classes of vertebrated animals will demonstrate
that security for the brain is the grand aim of
the contrivance, and that the modification it
Sustains in the case of Fishes and Reptiles is
for the purpose of carrying into effect some
additional design.

Considering the cranium as a capsule for the
brain, its form is necessarily determined by the
extent to which that organ is developed in the
several classes of animals; while, at the same
time, the nature of its organization is in harmo-
nious correspondence with their habits,and with
the external circumstances by which they are
surrounded. By pursuing this inquiry from the
lowest to the highest animals, it will be per-
ceived that, as respects both form and struc-
ture, additions are made in proportion as the
endowments are of a more and more exalted
character; and further, that these successive
changes of structure are the changes which the
human skull itself experiences in its progress
from a foetal to an adult condition.

The rudimentary part of the most elaborate
cranium is a sac consisting of two membranes
_ and an intervening gelatinous fluid; in the
next step of the formative process, this gelati-
nous fluid gives place to cartilage. A deposi-
tion of eels matter in this cartilaginous nidus
gives it firmness, but breaks up the sac into
isolated ununited patches. These. isolated
patches coalesce in definite numbers, and thus
establish a secondary and less numerous divi-
sion of ununited parts; these, in their turn,
approach and combine with each other, form-
ing a solid case of bone; and lastly, this solid
case resolves itself into two tables of different
structure, and a still further differing connect-
ing medium. In each and all of these states
through which the crania of the Mammalia
pass there is presented to us a type of the skull
in some lower animal.

In Fishes the cranium is little more than a
tubular continuation of the spine through the
head to contain a similar prolongation of the
medulla spinalis. These, however, are not in
contact. A mass of reticulated membrane,
holding in its cells a gelatinous fluid, forms the
real superior investment of the brain; while
the superjacent parietes are designed to afford
an extensive origin to the muscles of the body;
and as these muscles increase, so does the sur-
face of theirattachment. For this purpose it is
that the ossific deposits remain ununited, that, by
being simply in juxtaposition, or at most over-

ing each other, they may unfold them-
selves, and thereby admit of the head being
at all times in proportion to the rest of the

In Reptiles the skull is still further deve-
loped. It is charged more with earthy than
with animal matter; and this being loosely
distributed, tough spongy bones are the result.
The tardiness of their circulation does not
favour the combination of the individual por-
tions, and the bones are therefore for the most
part loose, although some of them unite by a

cies of anchylosis in the direction in which

efence is required.

725

In Birds the character both of form and
structure is greatly changed ; light, fragile, and
compact, it is (by reason of the high state of
vitality which prevails) so rapidly and com-
pletely ossified over its entire surface as to
afford no evidence, or but a very slight one, of
its original subdivision. In conformity with
the development of the brain, it extends itself
backwards, to each side, and upwards as well
as forwards, thus constituting a considerable
portion of the entire head.

In Mammiferous animals the skull is more
compact than that of Reptiles and more diffuse
than that of Birds. Its elementary portions
unite so as to form a determinate number of
bones which are either dovetailed together by
the interlacement of crooked processes with
which their edges are liberally studded, or flow
into each other so as to exhibit no trace of their
junction. Its structure is made up of two
osseous lamelle, called an inner and an outer
table, which are united by an areolar ossific
tissue, termed diploe, that adds greatly to the
defensive properties of the skull.

The Cranium (in human anatomy)is a hollow
bone of an ovoid figure; elongated from be-
hind forwards ; narrower before than behind ;
compressed on the anterior part of its sides ;
surmounting the face and spine, and projecting
considerably beyond the latter. It contains in its
parietes the organs of hearing, and contributes
to form the orbits, the nostrils, and the face.

The dome-like upper portion is termed the
calvaria, and the lower part is the base. The
former presents the synciput in front, the occiput
behind, the verter or bregma, (Bpexuc, from
Brees irrigo,) above, and the temples on the
sides.

Placed at the summit of the body and des-
tined to contain the brain, the skull is pierced
at its base by numerous foramina for the trans-
mission, ist, of the nerves which establish the -
communication between the brain and other
organs ; and 2dly, of the vessels which supply
the brain and its membranes.

From the inferior surface of the cranium, be-
tween its anterior and middle thirds, there de-
scend two columns which limit posteriorly the
boundaries of the face; so that it is anteriorly
to these columns that it contributes to form the
orbits and the nose, and consequently there the
bones which enter into the composition of the
face are fixed to it. Hence the surface of that
part is very irregular, presenting, in addition to
the foramina, depressions and elevations, sulci
and processes indicative of the articulation of
bones and the lodgement of other organs.
Posteriorly, between its middle and posterior
thirds, the base of the cranium overtops the
spine, and a great opening there establishes the
continuity of the vertebral canal with the inte-
rior of the skull; and the muscles which move
the head and maintain its equipoise being at-
tached around, but especially behind this open-
ing, the skull is strongly marked in that diree~
tion. The intermediate space or middle third
is above the pharynx, offering, centrally,a plain
surface to form the roof of that cavity, and,

726

laterally, rough surfaces and processes for the
attachment of muscles concerned in deglutition,
also some of the foramina already referred to,
for the transmission of the vessels and nerves
of the throat to and from the interior of the
skull, as well as the surfaces on which the
lower jaw moves.

The upper surface of the base conforming to
the base of the brain, there are larger depres-
sions on it for the anterior and middle lobes; a
deep pit or cavity for the cerebellum, and in
the centrea broad sulcus, which glides into that
pit, for the medulla oblongata, as well as strong
ridges and processes to afford attachment to the
membranous partitions which severally exist
between the cerebrum and cerebellum, the he-
mispheres of the former and the lobes of the
latter organ.

Thebonesinto which the cranium is separable
or of which it is immediately formed, are eight,
viz. the sphenoid, the frontal, the ethmoid, the
occipital, the two temporal, and the two parietal.
The first named bone is so placed as to be in
connexion with all the others, and to have
them grouped around it; so that the frontal
(F, fig. 370) and ethmoid are in its front, the

Fig. 370.

occipital (O, fig. 372) is behind it, the two
temporal (T, fig. 370) are on its sides, and
the two parietal (P, fig. 370) are above it.

The sphenoid bone (from oQny, cuneus, os
sphenoidale ; Germ. Sphenoidal-knochen, Keil-
knochen.) comprehends the quadrilateral mass
which forms the centre of the frame-work, the
anterior ribs which supportthe frontal and partly
the lateral domes, and the depending pillars
which form the boundaries of the face; it extends
to each temple, is behind and in part forms the
orbits and the nose, and is also behind but in
close connexion with the bones of the face.

The central portion is called the body, and
the diverging processes are named ale majores
and ale minores.

The body is of a quadrilateral figure, hollow
and divided by a partition into two chambers
(the sphenoidal cells, s, fig. 371), which open

CRANIUM.
through the medium of the posterior ethmoidal

cells into the superior meatus of the nose. On
its upper surface is a deep depression (ephip-
pium, sella turcica, fossa pituitaris ) for the lodge-
ment of the pituitary gland. The posterior bor-
der of this depression presents a crest, the corners
of which are slightly tumid, (posterior ephip-

pial, or clinoid processes, ) for the attachment of —

the tentorium, and this crest is prolonged down-
wards and backwards under the name of the
basilar process, to join the process of the same
name of the occipital bone; on each side
there is a depression (sulcus caroticus) for
the reception of the internal carotid artery,
and which also marks the situation of the
cavernous sinus. On its under surface may
be seen, on the median line, the processus
azygos (rostrum), which is wedged into the
base of the vomer, and on each side of it a line
indicating the articulation of the two plates of
which the vomer is formed. Still more out-
wardly there is a groove which is converted into
a canal by the application against it of the in-
ferior orbitary or sphenoidal process of the pala-
tine bone.

Fig. 371.

The anterior surface exhibits the openings of
the sphenoidal cells, having, between them, and
apparently a continuation of their septum, a
prominent ridge which articulates with the ver-
tical plate of the ethmoid, and, below them, the
triangular curved processes denominated the
turbinated processes of the sphenoid bone. Ex-

ternally to these foramina and turbinated pro- —

cesses on each side is a rough line for the arti-
culation, in its two superior thirds, of the
orbital plate of the ethmoid, and, in its inferior
third, of the orbitar process of the palatine bone.
To the outer side of this rough line is a smooth.
surface which contributes to the formation of
the orbit. fy

The posterior ce is rough, quadrilate

‘
+
“9

ne

and at an early age becomes indissolubly united —

to the basilar po of the occipital bon
(d, fig. 371); for which reason Scemmerrin

and Meckel have regarded as one, the occi-
ital and sphenoid bones, and as such have

escribed it under the name of os basilare.
This surface is bounded superiorly by the

basilar process before mentioned, which is

BULAN Ba} & dre os Vows

GOR be a Ra Lal A Bb oo Mi

tl I, Ll Sb eA MAIL ADM AAC LM Ai el) AM ea Atl Al LAA ae ir te peeeive me be Wrst

:4
r :
‘

-

CRANIUM. 727

placed with such a degree of obliquity, that it
may be questioned whether it be on the posterior
or superior surface of the body of the bone. It
is smooth, slightly concave, and on its edges
may often be seen the commencement of the
sulci basilares for the lodgement of the basilar
sinuses.

The ale majores are those large curved pro-
cesses, which, stretching outwards, forwards,
and upwards, contribute to form the middle
fossee of the skull, the orbits, and the temples.

The upper surface of each ala, that which in
part forms the middle fossa of the base of the
skull, is concave from side to side, and still
more so from behind forwards. Qn it are seen
(though not so distinctly) the digital impres-
sions which mark the lodgement of convo-
lutions of the brain on the cerebral surface of
the other bones of the skull. Close to the spot
where it departs from the body of the bone
there is a sulcus directed forwards, and ter-
minating in a round hole (foramen rotundum )
for the exit of the superior maxillary branch
of the par trigeminum or fifth pair of nerves.
More outwardly, and behind the plane of
the posterior edge of the body of the bone,
is a large oval opening (foramen ovale ), di-
rected downwards and slightly outwards for the
transmission of the inferior maxillary branch
of the par trigeminum and the entrance of the
ascending pharyngeal artery, which then be-
comes a meningeal vessel. Behind this fora-
men is another (the foramen spinale_), which is
very small, and affords entrance to the middle
meningeal artery.

On the inferior surface are seen the pterygoid
processes descending from the great wing where
it joins the body of the bone, to afford a resist-
ing surface against which the bones of the face
may be grouped. Anterior to these processes
is the termination of the foramen rotundum, the
opening of which is directed somewhat out-
wards, and from which there passes, outwards
and upwards, a groove (sulcus temporalis ) for
a deep temporal branch of the superior maxil-
lary nerve. Behind the pterygoid processes,
and extending from the base of the internal to
the extremity of the wing, is the sulcus Eusta-
chianus, which lodges part of the Eustachian
tube, and on the outer side of this sulcus are

- seen successively the foramen ovale and the

foramen spinale. Immediately behind the lat-
ter opening, and overhanging the Eustachian
tube, is the styloid process, to which the inter-
nal lateral ligament of the lower jaw is attached.
On the outer side of the pterygoid processes is
a plain surface forming part of the zygomatic
fossa, and bounded externally by a crest, which
marks the division between the zygomatic and
the temporal fosse, and which intervenes be-
tween the superior attachment of the external
pterygoid and the inferior attachment of the
temporal muscles.

e pterygoid processes consist of two
plates, with a triangular separation inferi-
orly, and they are called the erternal and the
internal pterygoid processes or plates. The
external is broader, thinner, and is directed

more outwardly than the internal; its outer
surface, which also looks a little forwards,
gives attachment to the external pterygoid, its
inner to the internal pterygoid muscles. The
internal is nearly vertical ; it is pierced longi-
tudinally at its base by the canalis Vidianus
for the passage of the vessel and nerve which
bear that name ; at its inferior extremity there
is a hook (the humular process), which acts
as a pulley for the tensor palati muscle, the
attachment of which to the outer side of the
internal pterygoid process is shewn by a sul-
cus which is most evident at the base (fossa
navicularis ) ; to its anterior edge is applied a
thin plate of the palatine bone, thus sepa-
rating it from the superior maxillary, and to
its posterior edge is affixed the aponeurotic
origin of the superior constrictor of the pha-
rynx. The concavity between the two pro-
cesses is the fossa pterygoidea which is occu-
pied by the internal pterygoid muscle, and
the notch at the lower part (the hiatus pala-
tinus ) is filled up by the pterygoid process of
the palatine bone.

The external surface of each ala is continu-
ous with the inferior; it is concave from before
to behind, and convex from above downwards ;
it contributes to the formation of the temporal
fossa, and the continuation of the sulcus tem-
ae is evident at its anterior part (S, fig.
373).

The anterior surface forms the major part of
the external wall of the orbit, is oblong, di-
rected forwards and inwards, and is narrower
at its extremities than in its middle.

The superior border of the great wing sepa-
rates the orbital from the cerebral surface ; it
presents a sharp smooth edge on its inner half,
and a rough irregular surface on its outer half;
it is convex, and its convexity is directed up-
wards, forwards, and inwards. The sharp
internal half concurs with the ale minores to
form the sphenoidal fissure, which will be de-
scribed with those processes. The external
rough half becomes broader as it passes out-
wards, so as to produce a triangular indented
surface, the outer edge of which is prolonged
at the expense of the inner table in such a
manner that it overlaps the frontal bone which
is affixed on it, and this prolongation is con-
tinued without the indented surface, so as to
grasp the anterior inferior spinous process of
the parietal bone.

The external border is nearly the reverse of
the former. It is concave, and looks outwards
and backwards, and it is articulated in its entire
extent to the squamous portion of the temporal
bone, by which it is overlapped in its anterior
third, and receiving and supporting it in its
two posterior thirds ; the former at the expense
of its outer table, the latter at that of the in-
ternal.

The posterior border is applied against the
outer side of the petrous portion of the tem-
poral bone, and extends from the body of the
sphenoid to the posterior extremity of the ex-
ternal border. e junction of these two bor-
ders forms the spinous process, which is received

728

into the angle of the petrous and squamous
portions of the temporal bone. The laxator
tympani muscle arises from this process, and
the styloid process before described descends
from it. The angle which exists where this
border departs from the body, in part forms the
Soramen lascheai anterius, an opening which,
in the recent skull, is closed by cartilage.

The anterior border consists of two portions
which join with each other at an angle. Of
these the upper is indented, separates the or-
bital from the temporal surface, and articulates
with the malar bone. The inferior portion is
smooth, and forms with the palatine and supe-
rior maxillary bone, the jfisswra lacera orbitalis
inferior.

The ale minores are on the upper and an-
terior part of the body of the bone; they ex-
tend outwards over the superior borders of ‘the
greater wings, and, gradually tapering, they at
last end in a point.

The upper surface of each ala minor is smooth,
and partly forms the anterior fosse of the skull.
The processus ethmoidalis is a thin lamina
somewhat triangular in form, prolonged for-
wards on the median line to articulate with the
cribriform plate of the ethmoid bone. Passin
backwards from this process, there is a slightly
elevated line separating the depressions which
on each side receive the olfactory nerves, and
terminated posteriorly by a tubercle (processus
olivaris) marking the decussation of the
optic nerves, and having upon it a transverse
depression for the lodgement of their com-
missure. This depression terminates on each
side in the foramen opticum for the passage of
the optic nerve and the ophthalmic artery, in
such a manner that the lesser ala appears to arise
by two roots, one above and the other below
the foramen. From the sides of the processus
ethmoidalis there pass the two transverse spi-
nous processes, being the anterior serrated mar-
gins of the wings; they are articulated to the
orbitar processes of the frontal bones, and
sometimes join by their extremities the great
wings; thereby, in such a case, converting the
superior orbital fissure into a foramen without
the aid of the frontal bone. The posterior
margins of the ale minores are smooth and
less sharp than the anterior; they are pro-
longed backwards and inwards, so as to form
on each side a short and thick triangular pro-
cess, the apex being directed backwards, called
the anterior ephippial (anterior clinoid ) pro-
cess, to which the cornua of the lunated margin
of the tentorium are attached.

The inferior surface of each ala minor forms
the posterior part of the orbit. On it is seen
the opening of the optic foramen, and under-
neath it, between the smaller and the greater
wings, the fissura lacera orbitalis superior.
This fissure is completed into a foramen by
the articulation of the frontal bone to the
sphenoid, when it appears as an elongated
triangular opening directed from below up-
wards and from within outwards. Thus is
formed the foramen lacerum orbitale superius,
which allows to emerge from the skull the

CRANIUM.

third, fourth, the ophthalmic division of the
fifth, and the sixth pair of nerves, and to
enter from the orbit the ophthalmic veins.

The articulations then of this bone are, to
the ethmoid, by the ethmoidal process and
the fore part of the body; to the frontal, by the
transverse spinous processes, and the summits
of the great wing; to the parietal, by the tips ;
to the temporal, by the external and posterior
borders, and to the malar, by the anterior bor-
ders of the same wings; to the occipital, by the
basilar process; to the palatine, by the ptery-
goid processes and adjacent part of the body ;
and to the vomer, by the azygos ess.

The sphenoid bone is developed by nu-
merous points of ossification, some of which
coalesce before the others appear; and during
the period of intra-uterine life the union of these
parts is so rapid, that, at birth, the bone con-
sists but of three parts, one central, compre-
hending the body and smaller wings, and two
lateral, each involving a great wing and its cor-
eS Mee pterygoid processes.

' So early as the third month there appear six
points,of ossification, two in the great wings,
two in the internal pterygoid processes, and
two in the smaller wings. During the fourth,
fifth, and sixth months six points are esta-
blished in the body, one on each side the
median line, afterwards another between these
and the corresponding greater wing, and ulti-
mately another between the optic foramen and
those already existing. During the sixth month
also a deposit appears between the optic fora-
men and the olivary process. In the course of
the seventh month the six points of ossification
in the body run into each other; in the next
month a coalition takes place between those
in the pterygoid processes and those in the
greater wings, and shortly afterwards a similar
union occurs between the point in the small .
wing and that near the optic foramen. To-
wards the termination of the ninth month the
two smaller wings are associated together,
which then become attached to the already
formed body, and thus constitute at birth the
three pieces which exist at that epoch.

In the early period of extra-uterine life these
three portions unite into one, the great
wings acquire a more determined curvature 4
than they at first possessed, the pterygoid pro-
cesses lose their striated appearance, and ex-
hibit more completely their fossa; but it is
not until after the lapse of years that the ab-
sorbing process, which, commencing in the
centre of the body, developes the sinuses, is _
terminated, so that during childhood there is
not only an absence of these sinuses, but of
the openings leading from them and of the tur- —
binated processes which are fixed to their front. —

2. The frontal bone ( 0s frontis, corona ; Germ. —
das Stirnbein,) (¥, fig. 370, 373,) is situated
at the anterior part of the cranium, forming
part of the vault and part of the base, but —
considerably more of the former than it does
of the latter. It comprises the two anterior
ovoidal domes and the anterior portion of the
longitudinal curved rib of the general frame-

work, which will be afterwards more fully ex-
plained. The convexity of these domes is turned
outwards and forwards in such manner that the
circumference may abut against the longitu-
dinal rib internally ; and, behind against the
anterior rib in the base and a portion of the
circumference of the lateral dome in the vault.
That portion which is in the base is, as it were,
pressed upwards to increase the space of the
orbit, but not so much so as, at first sight,
might appear; for on the external surface of
the junction of the two portions there is an
extraordinary development of the bone, which
projecting over the face destroys the uniformity
of surface and causes the orbitar portion to
appear more elevated than it is in reality, and
even to pass backwards at right angles with
the other.

Fig. 372.

The external surface of the frontal portion
in its upper two-thirds is smooth, of an equa-
ble convexity and directed backwards; its
inferior third is more vertical, and its convexity
is interrupted by prominences. On the me-
dian line it exhibits evidence of its original
division into two parts, and this generally by
a slight ridge, although in some instances there
is a linear depression of equal indistinctness.
Thisline is terminated by the nasal prominence,

which has immediately above it a smooth tri-
angular surface (glabella), and below it a
rough notch for the articulation of the nasal
and superior maxillary bones. From the
_ centre of this notch there is a projection (pro-
_ cessus nasalis), on the fore part of which are
. the nasal bones, and to its back part,
is grooved, the ethmoid bone is ap-
_ On either side of the median line there is,
at about the distance of an inch where the
_ middle joins with the lowest third of the bone,
the frontal eminence ( eminentia frontalis, pro-
ssus primi genii), which marks the centre
of ossification, and the prominence of which
| ipa as to the age of the subject. Be-
low this eminence, bounding the glabella, and
inclining downwards and inwards towards the
nasal prominence (with which, in fact, it is
te timately confounded), is a pyramidal protu-
_ berance, varying very much in distinctness in
VOL. I.

CRANIUM.

729

different individuals, (processus frontalis, )
more evident below than above, and indicating
the situation of the frontal sinus. There is a
slight depression underneath and to the outer
side of this process, and, finally, the super-
ciliary ridge terminates the frontal portion of
the bone. This ridge is more prominent at its
outer than at its inner side; its extreme points
are called externul and internal angular prc-
cesses, to the former of which the malar bone
is articulated, to the latter the os unguis; at
the junction of its inner and middle thirds
there is a hole (foramen supra orbitarium ),
or otherwise a notch, for the passage of the
frontal branch of the ophthalmic vessels and
of the ophthalmic division of the fifth pair of
nerves. Behind the external angular process
there is a depression (fossa temporalis) which
forms part of the temporal fossa ; a part of the
temporal muscle is attached to it, and it is
bounded above by a dine (linea temporalis )
which is continuous with the outer margin of
the external angular process, and to which is
attached the temporal aponeurosis.

Fig. 373.

The posterior or cerebral surface of the
frontal bone is concave, is marked by depres-
sions which correspond with the convolutions
of the brain, and by sulci for the lodgement of
the arteries of the dura mater, and is conti-
nuous inferiorly with the orbitar portion; cor-
responding to the eminentie frontales there are
two depressions, and on the median line there
is a sulcus (sulcus longitudinalis) for the re-
ception of the longitudinal sinus, on the edges
of which sulcus may sometimes be seen the
fossee Pacchionii for the glands of the same
name. This sulcus as it descends is generally
replaced by a dense crest, which projects con-
siderably into the cavity of the cranium ; to it
and to the edges of the sulcus, the falx cerebri
is attached ; and at its lowest point it is bifid,
so that, by its being applied against a similar
bifurcation of the processus cristatus of the
ethmoid bone, it contributes to form the fora-

men cecum.
3B

730

The orbitar portion by its wpper surface
supports the anterior lobes of the brain, and
its under surface forms the root of the orbits.
It is divided into two processes by a longitu-
dinal notch, which corresponds to the roof of
the nose.

The orbitar process of either side is convex
in both directions on its upper surface, and
the mammillary eminences and digital im-
pressions formed by the intergyral spaces and
convolutions of the brain are of a decided
character. On its under surface it is concave
and triangular, the base being directed for-
wards; at its anterior and outer part there is a
Fossa (fossa lachrymalis) for the lachrymal
gland, and which is overhung by the external
orbitar process; at its anterior and inner part,
near to the internal orbitar process, and be-
tween it and the foramen supra-orbitarium,
there is a small pit (fossa trochlearis ) to which
is fixed the cartilaginous pulley in which plays
the tendon of the superior oblique muscle of
the eye; at the middle of its inner edge there
is a notch, which, applied to a similar notch of
the ethmoid bone, constitutes the foramen
orbitarium internum anticum, through which
pass the ethmoidal twig of the ophthalmic
branch of the fifth pair of nerves, and the an-
terior ethmoidal branch of the ophthalmic
artery; and a little behind this there is another
notch, which by a like contrivance forms a hole
(the foramen orbitarium internum posticum )
for the passage of the posterior ethmoidal
branch of the ophthalmic artery and corres-
ponding vein.

The notch which is between the orbitar pro-
cesses is the hiatus ethmoidalis (incisura
ethmordalis ), and in the cranium it is filled up
by the cribriform plate of the ethmoid bone.
Its longitudinal is twice the length of its trans-.
verse diameter; anteriorly, it is bounded by
the notch which, in part, forms the foramen
cecum and the posterior surface of the nasal
process; posteriorly, it is open; and its sides
are bounded by the commutual edges of the
orbitar processes, the tables of which are sepa-
rated in such a manner as to communicate with
the ethmoidal cells and close them at the
upper part, and at the anterior part of the
notch to communicate also with the frontal
sinuses.

The frontal sinus is formed by the separation
of the two tables of which the bone is com-
posed, and by the absorption of the diploé ;
they are usually separated by a septum, and
they communicate .on each side with the mid-
dle meatus of the nose in the manner indi-
cated above.

The posterior and upper border of the bone
as far down as the posterior extremity of the
inferior margin of the fossa temporalis, is arti-
culated to the parietal bones; and it will be
remarked that rather more than the middle
third of it advances upon and secures those
bones at the expense of their outer table, while
the inferior portions of it are in their turn
grasped by each parietal bone respectively,
the outer table of the latter advancing, at this
part, upon the inner table of the former.

CRANIUM.

Behind the external angular process, be-
tween the temporal fossa on the one hand and
the orbitar process on the other, there is a
triangular rough surface which is implanted on —
a similarly-disposed surface of the great wing
of the sphenoid bone. The posterior margin
of this surface is in apposition with eed
of the thin extremity of the small wing ef the
sphenoid, to which also-is articulated the re-
maining portion of the posterior border of the
orbitar process; but with this difference, that,
while in the former instance the edges are plain
and simply applied to each other, in the latter
the margins are denticulated, the sphenoid
overlapping the frontal so as to render the
roof of the orbit secure.

Thus the frontal bone articulates by the pos-
terior borders of its two portions, with the
parietal and sphenoid; by the inner edges of
its orbitar processes, with the ethmoid ; by its
nasal process, with the nasal; by its internal
angular process, with the lachrymal; by the
surface between the nasal and internal angular
processes, with the superior maxillary ; and by
its external angular process, with the malar
bones.

This bone in the feetus, and for nearly two
years after birth, consists of two pieces, the
first deposit in eaeh being at the prominence
already indicated. From this point the ossific
matter radiates, and approaching that from the
opposite side, the two combine so as to form
on the median line a suture which is speedily
effaced. Nevertheless it occasionally happens
that complete union does not take place, and
then the suture persists through life.

The ethmoid bone (nOroesdns, nOuos, cribrum,
os ethmoideum; Germ. Ethmoidal-knochen_) com-
pletes that portion of the base of the cranium,
anterior to the sphenoid, which is not supplied
by the frontal. It is however devoted less to
the skull than to the face, with many of the
bones of which it is connected; and it con-
tributes greatly to form the nostrils and their
septum, as well as both of the orbits.

As an element of the cranium it is very
simple, being merely a plate connecting the
two orbitar processes of the frontal bone, and
having on its median line a ridge, which joins
the frontal spine before, to the body of the
sphenoid bone behind. This plate is the eri- —
briform plate or process; it is notched poste- ~
riorly where it reccives the ethmoidal process —
of the sphenoid bone, the apex of which pro- —
cess is applied to the posterior extremity of the
central ridge. Advancing forwards, this ridge —
quickly springs upwards as a pyramidal pro=
cess (the crista galli, or processus cristatus ),
to which the falx cerebri is attached; its pos-
terior edge is long and oblique, its anterior is
shorter, more vertical, and it terminates if
feriorly in two slightly divergent plates, so a:
to form by their articulation with the fron
bone the foramen cecum. On each side of th
crista galli, more especially towards the for
part, the cribriform plate is channelled for
reception of the olfactory nerves, and ea
channel is perforated by numerous foram
for the transmission of the ramific

Ee

of the olfactory nerves aang cribrosa ).
These openings are variable in their number,
and differ from each other in their size and
modes of termination; those nearest the crista
galli are the largest, and of them one or two
of the anterior ones are very considerable; the
smallest are situated on the outer edge of the
cribriform plate, and both of these sets are
the orifices of canals which terminate, the
former about the root and upon the sides of
the septum, the latter on the outer wall of the
nose ; those which are intermediate and in the
centre of the channel, are complete foramina,
and open on the opposite surface of the plate.
Immediately in front of the inner set of fora-
mina, there is, between the crista galli and
cribriform plate, a fissure which gives passage
to the ethmoidal nerve and vessels.

From the ufder surface of the cribriform
plate and at right angles with it, there descend,
on the median line, the nasal lamella, and,
on each side, a cellular mass which partly
forms the outer wall of the nostril and the inner
wall of the orbit.

The nasal lamella, or vertical plate, forms
the upper portion of the septum narium; it is
immediately underneath the crista galli, and
becomes gradually thinner as it descends; its

_. anterior border is rough, thicker above than
below, and articulates, first, with the nasal
process of the frontal bone, and, secondly,
with the nasal bonesthemselves ; its posterior
border is also rough and is articulated to the
crest on the fore part of the sphenoid bone;
its inferior border is, in its posterior half,
thin and inclined downwards and forwards to
be articulated to the vomer, and, in its anterior
half, somewhat thicker and rougher, and in-
clined downwards and backwards to be arti-
culated with the triangular cartilage of the
nose; its sides are plain, and exhibit sulci which
are continuous with the foramina that open on
its root.
On each side of this lamella and between it
| and the lateral masses there is a space which
is encroached upon in the. middle more than it
is above or below, and a portion of the cribri-
form plate forms its roof.
The lateral masses are delicate in their struc-
ture and complicated in their arrangement.
Each consists of a number of cells (cellule
ethmoidales ), which are divided ‘by a partition
into an anterior and a posterior set, with the
former of which the frontal sinus communi-
ates, and with the latter the sphenoidal. The
outer surface of each lateral mass is compact
‘and smooth, and constitutes the greater portion
of the inner wall of the orbit. This is the
orbitar process or os planum, which articulates
_ above with the frontal bone, below with the
_ Superior maxillary and palate bones, behind
with the sphenoid, and in front with the la-
On its upper border are seen the
‘© notches which assist the frontal in forming
ne anterior and posterior orbital foramina.
‘the inner surface of this cellular mass, that
Which looks towards the nasal lamella, is ren-
tered irregular by two curved processes (the
yerior and middle turbinated processes), of

CRANIUM.

731

which the upper one is smaller, delicate, re-
gular in its curve, and is seen only on the
posterior half of the wall; the other is larger,
more spongy, and extends the entire length of
the wall. Both of them are convex on the
side next the cavity of the nostril, and concave
on that which looks towards the cells ; but the
inferior is also at its lower edge again curled
in such a manner as to offer a convexity on both
of its surfaces. Between the two turbinated pro-
cesses there is a triangular space (the superior
meatus ) the apex of which is directed forwards,
and in which there is an opening commu-
nicating with the posterior ethmoidal cells.
Underneath the middle turbinated process, and
bounded by its concavity on the one hand and
the cells on the other, is the middle meatus ;
into which open the anterior ethmoidal cells,
and the tubular communication with the frontal
sinus, called infundibulum.

e connexions of this bone are, behind to
the sphenoid ; in front to the frontal and nasal
bones; laterally by its upper borders to the
orbitar processes of the frontal, by its under
borders to the same-named processes of the
superior maxillary and palate bones, and by
its anterior border to the lachrymal; by the
under edge of its middle vertical plate to the
vomer and triangular cartilage; and by the
anterior extremity of the outer surface of the
middle turbinated process to the inferior tur-
binated bone. !

The ethmoid is the most tardy in its deve-
lopment of all the bones of the cranium. The
lateral masses exhibit each of them an ossific
deposit about the middle period of intra-
uterine life, but neither the cells nor turbinated
processes are much developed at birth, at
which time also the central portion is carti-
laginous. The ossification of this part pro-
ceeds from above downwards, so that the
crista galli is completely formed while the
lower part of the nasal lamella is yet cartila-
ginous. During infancy the cribriform plate
becomes narrower, curved, and as it were
compressed ; the nasal lamella advances for-
wards; and the spaces between the septum
and outer walls are considerably increased.

The occipital bone (0s occipitis ; Germ. Occi-

pital-knochen, Hinterhaupts-knochen, ) is situ-

ated behind the sphenoid, and forms the pos-
terior part of the base of the cranium and the
contiguous projection of the occiput. Its
figure is that of a lozenge with its anterior
angle truncated, and is so curved as to be
generally concave on one surface and convex
on the other. The inferior and anterior half
of it is situated between the two temporal
bones; the superior and posterior half is be-
tween the posterior margins of the two pa-
rietal.

At its anterior part it is pierced by a large
elliptical foramen (the foramen magnum),
through which there pass, from the skull, the
medulla spinalis and its membranes, the sinus
venosus and the spinal arteries ; and, into the
skull, the vertebral arteries, the posterior me-
ningeal arteries, and the nervus accessorius.

On the cerebral surface the internal crucial

3B 2

732

spine divides it into four fosse, the two supe-
rior of which are the fosse cerebri for the pos-
terior lobes of the cerebrum, the two inferior,
the fosse cerebelli, for the hemispheres of the
cerebellum ; the former being marked by the
convolution of the brain, they are not so smooth
as those which lodge the cerebellum. The
lower limb of the crucial spine is prominent,
and arises by a bifid root from the margin of
the foramen magnum; the upper limb is
grooved for the reception of the longitudinal
sinus, and to its borders the septum cerebri is
attached ; this groove is mostly directed to one
side or the other, and generally to the right ;
to the lateral limbs the tentorium is fixed, and
the grooves which are on them contain the
lateral sinuses. At the point where the trans-
verse bisects the vertical portion of the crucial
spine, it is very prominent, is called the inter-
nal occipital protuberance, and marks the situ-
ation of the torcular Herophili.

In front of the foramen magnum, ascending
obliquely towards the sphenoid bone, and nar-
rowing in its ascent, is the upper surface of
the basilar process, which is concave from side
to side*for the lodgement of the pons Varolii
and medulla oblongata, and exhibits on each
margin a depression (the sulcus basilaris ) for
the basilar or inferior petrosal sinus.

On either side of the foramen magnum is a
groove which advances from without inwards,
and from behind forwards, and lodges the ter-
mination of the lateral sinus. The anterior
extremity of this groove turns downwards and
forms a large notch (the fossa jugularis ), which
is bounded on the outer side by a strong rough
process (the processus jugularis ), and on the
inner side by a smooth oval eminence which
is situated between it and the sulcus basilaris,
and below which is the orifice of the foramen
condyloideum anticum for the passage of the
motor linguz nerve.

The external convex surface, in that part
which is behind the foramen magnum, is di-
vided into an inferior rough, and a superior
smooth, triangular portion. The division be-
tween the two is marked by a curved line
(the superior occipital ridge), which abuts on
the petrous masses of the temporal bones,
and exhibits in its centre the tuberose process,
or the external occipital tubercle, to which the
ligamentum nuche is attached. From the
ridge next to the tubercle the occipito-frontalis
and trapezius muscles arise, and, still more
outwardly, the splenius capitis and the sterno-
cleido-mastoideus are attached. From the tu-
bercle to the foramen magnum extends a
longitudinal spine, which is bisected in its
middle by a second curved line (the inferior
occipital ridge), and constitutes, thereby, the
external crucial spine. On each side of the
spine and between the two ridges, there is a
considerable rough depression for the attach-
ment of the complexus, and, to the outer side
of it, one which is smoother, for the trachelo-
mastoideus. Between the inferior ridge and
the foramen magnum, there are on either side
of the longitudinal spine, indications of the
attachment, in succession, of the recti capitis

CRANIUM.

postici minores et majores and of the obliquus
capitis superior. On the outer side of this region
is the sulcus occipitalis, which runs backwards
and upwards between the surfaces of attach-
ment of the trachelo-mastoideus and the com-
plexus, and is formed by the occipital artery. —

Underneath the anterior half of the margin
of the foramen magnum are the condyloid pro-
cesses, two elongated articulating eminences,
convex in both directions, wider in the middle
than at either end, inclined from above down-
wards, from behind forwards, and from with-
out inwards, and having their internal edges
below the level of the external. On the inner
side of each process is a rough surface for the
attachment of the odontoid ligament; on the
outer side is a ridge (the processus lateralis )
which ends in the jugular process, and gives
insertion to the rectus capitis lateralis; ante-
riorly is the anterior orifice of the anterior
condyloid foramen; and_ posteriorly there is a
depression in which is sometimes seen a fora-
men (foramen condyloideum posticum ) through
which a vein of the scalp communicates with
the terminal portion of the lateral sinus.

In front of the foramen magnum is the
under surface of the basilar process, which,
by reason of the superior thickness of its an-
terior extremity, is not so oblique as it appears
on its upper surface. There is a slight tuber-
cle on the middle line to which is. fixed the
middle constrictor of the pharynx, and behind
it, on both sides, a transverse line for the su-
perior constrictor, between which and the
foramen are depressions caused by the recti
capitis antici majores et minores.

The superior angle of this bone is applied
on the junction of the two parietal, and the
serrated borders which extend from it to the
lateral angles are articulated to the posterior
borders of the same boues. The upper angle
itself and more than half of the borders pro-
ceeding from it, overlap the parietals, but in
the remainder of their extent the latter bones
overlap the occipital; in each case the arrange- ~
ment being the same as that which exists be-
tween the parietal and the frontal bones.

From the /ateral angles to the jugular pro-
cesses, a rough but not denticulated border
articulates it to the posterior border of the
mastoid portion of the temporal bone. Im-
mediately in front of the jugular process is the
fossa jugularis, which forms, in common with
the temporal bone, the foramen jugulare or
JSoramen lacerum posticum in basi cranii, —
through which emerge the jugular vein, the
pneumo-gastric, glosso-pharyngeal, and spinal
accessory nerves. The rest of the border from
the fossa jugularis to the anterior angle is in
apposition with the petrous portion of the
temporal bone, but the quantity of cartilage
between them is too large to admit of ther
being any fixed articulation at this part.

The anterior angle itself is truncated ar
presents a rough quadrilateral surface, whi
articulates, and, indeed, consolidates itself,
an early period of life, with the basilar proe
and body of the sphenoid bone. This un
is so complete and so similar to the uni

which takes place beween the several elements
of the bones of the cranium, that Soémmering
and Meckel have described the two as one
bone, under the name of os basilare or os spheno-
oceipitale.

he connexions of this bone are few and
simple, being, in its superior half, with the
parietals ; in its inferior half, with the tem-
porals; at its anterior extremity, with the
sphenoid; and, by its condyles, with the
atlas.

At birth this bone is separable into four dis-
tinct portions, one being in front, one behind,
and one on each side of the foramen magnum,
the border of which is, consequently, not then
completed. The anterior and two lateral por-
tions are formed by the extension of ossific
matter from one point of deposit in each; but
that posterior to the foramen is produced from
many points, in the number of which ana-
tomists are not agreed. The ossification com-
mences in the lower part, at some distance
from the foramen, by one point on each side
of the median line; and before they have
_ completely approached each other, two ana-
logous deposits appear in the upper part, which
coalesce before the upper and lower pieces are
joined. This occurs during the fourth month,
at which time the inferior and broad part dis-
plays on each side another point of ossification
on a level with the spot where the process
first commenced ; in the fifth month the whole
of these are consolidated into one piece. It
often happens, however, that other deposits
are formed, especially in the upper part ; and
_ frequently they refuse to merge into the others,
continuing then to be distinct through life as
separate small bones having their own serrated
_ whargins to articulate with the adjoining struc-
tures.

_ The lateral pieces (those which comprehend

_ the condyles, and lateral and jugular pro-
cesses) commence their formation about the
fourth month; and the anterior piece is the
last in the order of development.

‘The temporal bone (os temporum ; Germ. das
_ Schlafenbein.) One is situated on each side
_ of the sphenoid and lower half of the occipital
bone ; they complete the base of the cranium
and form the inferior part of the sides of the
_ vault.

__ For the purposes of description it is usually
_ divided into three portions; one, strong and
compact, in the base and between the middle
and posterior fosse, the petrous; a second,
-tumid and less dense, behind the ear, the

_ two, thin and scaly, situated in the temple,
the squamous.
_ The petrous portion is an elongated, pyra-
_ midal mass, of which two of the surfaces enter
into the formation of the cavity of the cranium,
_ and the third is underneath. It is situated on
_ aline which, if prolonged, would extend from
_ behind the ear to the opposite external angular
; of the frontal bone; but it is limited
_by the body of the sphenoid. It occupies the
_ Space between the posterior border of the ala
Major of the sphenoid and the basilar process

CRANIUM.

_ mastoid; and a third rising from the former.

733

of the occipital bone, in the angle of which its
free extremity is impacted. In its substance
is contained the labyrinth of the ear.

Of the two surfaces which are in the cra-
nium, one is superior, the cerebral; the other is
posterior, the cerebellar.

On the cerebral surface near its middle, is a
smooth, convex, and transverse elevation (the
processus semicircularis ), produced by the su-
perior semicircular canal of the labyrinth ;
immediately in front of this is a depression on
which the Gasserian ganglion lies; more out-
wardly and running lengthwise, is a faint
sulcus (the sulcus Vidianus ), which terminates
at a small opening (the hiatus Fullopit ) for the
entrance of the Vidian nerve into the aque-
ductus Fallopii.

On the cerebellar surface is seen the foramen
auditorium internum, the superior and posterior
part of the margin of which is more prominent
than the anterior, which, in fact, degenerates
into a sulcus. It is the commencement of a
canal (the meatus auditorius internus) into
which pass the acoustic and facial nerves, and
the bottom of which is divided by a ridge into
two unequal depressions; the upper one being
the fossula parva, in which is the orifice of the
aqueduct of Fallopius for the exit of the facial
nerve; the lower one being the fossula magna,
in which are several minute perforations for
the acoustic nerve. Behind the foramen audi-
torium is an indistinct slit, which is the ter-
mination of the aqueductus vestibuli; above
and rather anterior to this slit is a triangular
orifice for the entrance of vessels; and below it,
extending to the foramen lacerum posticum,
is a slight groove.

Between the cerebral and cerebellar surfaces
there is a sharp ridge on which there isa
groove (the sulcus petrosus ), more evident pos-
teriorly than anteriorly; to the ridge is attached
the tentorium ; the groove lodges the petrosal
sinus.

The under surface is divided into two parts
by a sharp, prominent ridge, which has on
either side of it a considerable fossa. That on
its outer side is the fossa parotidea for the
upper part of the parotid gland; that on its
inner side is a thimble-like depression (the
fossa jugularis ), which forms with the occipital
bone the foramen lacerum posterius. In this
bone, however, it is not so wide as it is in the
occipital; from which it results that the fora-
men is imperfectly divided into two parts—
the anterior for the nerves, the posterior for
the vein; and it is the latter organ which is
lodged in the fossa jugularis of the temporal
bone. The fossa parotidea is limited, above
and in front, by a fissure (the fissura Glasseri ),
which penetrates to the tympanum and gives.
exit to the chorda tympani and entrance to
the laxator tympani muscle; behind, by the
external auditory process. The margin of the
foramen auditorium externum, which is ellip-
tical, has its long diameter vertical, and is
the commencement of the meatus auditorius
externus; a tube which is curved a little
downwards, is more expanded at its extre-
mities than in its middle, and terminates at

734

the membrana tympani, in front, by a sulcus
which is situated on the border between the
cerebral and under surfaces, and passes back-
wards, between the petrous and squamous
portions as a canal (the canalis Eustachianus ),
which is divided by a lamina of bone, called
the processus cochleariformis, into two parts,
the inferior of which contains the Eustachian
tube, and the superior the tensor membrane
tympani muscle. Immediately behind the
fossa jugularis there is a rough surface, for the
articulation of the jugular process of the occi-
pital bone; and to the outer side of this sur-
face is the foramen stylo-mastoideum for the
exit of the facial nerve. In front of and close
to this foramen, and between it and the jugular
fossa, is the long pointed process (the styloid
process ) for the attachment of the stylo-maxil-
lary and stylo-hyoid ligaments, and the stylo-
pharyngeus, stylo-glossus and stylo-hyoideus
muscles; this process is embraced on the
outer side at its root by a portion of the ridge
separating the parotid and jugular fosse ; that
portion is called the vaginal process. In front
of the fossa jugularis are two foramina; one
very large, the foramen caroticum ; the other
very small, to the inner side of the former and
nearly on the margin between this and the
eerebellic surfaces, being the termination of the
aqueduct of the cochlea. The foramen caro-
ticum is the inferior opening of the canalis
caroticus, a canal which exists in the bone,
and consists of two parts that are at right
angles with each other—the inferior, short,
vertical, and extending upwards from the fo-
ramen caroticum into the substance of the
bone; the superior, horizontal, running length-
wise, and extending to the end of the petrous
process: in this canal there pass the carotid
artery to the cavity of the cranium, and a
filament of the nervus abducens, as well as
one of the Vidian, to the neck. A rough sur-
face is observed anterior to the foramen caro-
ticum for the attachment of the levator palati
and the tensor tympani muscles.

The outer and posterior extremity of the
petrous is confounded with the mastoid and
squamous portions; the inner and anterior is
open, and the bone is so much removed at its
upper part (to allow the carotid artery to pass
upon the body of the sphenoid) that it there
appears more like a deep groove than a tube.
This is filled up in the recent subject by a
plate of cartilage, but in the dried skull, when
this cartilage has been removed, there is found
an opening, between the sphenoid bone and
this extremity of the temporal, which is called
the foramen lacerum anticum.

The mastoid portion is situated at the outer
end of the petrous, and behind and below the
squamous. It is of a nipple-like shape, with
an upper horizontal denticulated border, with
which the posterior inferior angle of the pari-
etal bone articulates ; and with a posterior semi-
circular border which is joined to the occipital :
in both directions it is overlapped by the bones
to which it is joined, except at the lower part,
where it is applied to the occipital by a sort
of harmonic suture.

On its inner surface there is a deep, semi-
circular sulcus (the concavity looking back- —
wards) which traverses its entire length; it
receives the lateral sinus from the parietal bone
and transmits it to the lower part of the occi-
pital: there is generally observed in it a fo-
ramen (the foramen mastoideum), through:
which a vein of the scalp communicates with
the sinus.

Its outer surface is roughened and gives _
attachment to the sterno-cleido-mastoideus, .
and sometimes to the trachelo-mastoideus; it
terminates below in the mammillary eminence,
called the mastoid process, behind and to the
inner side of which are two grooves—the one __
nearest fo the process (the sulcus digastricus} _
very evident, for the attachment of the digas-
tricus ; the other nearly on the articulating edge
(sulcus occipitalis ), less distinct, for the occi-
pital artery. :

The squamous portion rises upwards from
the mastoid, and part of the outer border of
the petrous portions ; it has a semicircular mar-
gin which embraces the parietal and sphenoid

ones.

Its internal surface, which is concave, con-
tributes to form the middle fossa of the cra-
nium, and exhibits strongly the depressions
and elevations which correspond to the con-
volutions of the brain, and to the spaces
between them. At its anterior part, and com-
mencing at the angle between it and the pe-
trous process, there is a groove which runs
upwards and divides into other grooves, some
of which pass backwards; these are formed
by the middle meningeal artery and its branches.
The external plate of its border is prolonged
upwards, in such a manner that this surface is
surmounted by a rough articulating line, of
considerable breadth, which is applied on the
outside of the parietal and partly on the sphe-
noid bone.

The external surface is slightly convex, is
smooth, and there may be often seen indica-
tions of deep branches of the temporal artery
having passed over it. It forms in part the
temporal fossa, and the temporal muscle is
attached to it. At its lower part, a process
(the zygomatic process) passes transversely
outwards, and is then twisted on itself in a di-
rection forwards, after the fashion of the ribs at
their angles; so that the surface of the process
which would have been superior becomes
internal, and that which would have been in-
ferior becomes external. This process has
two roots, an anterior or transverse and a pos- —
terior or longitudinal. The former is a convex —
elongated eminence, situated transversely and —
in front of a fossa (the fossa articularis), im
which the condyle of the lower jaw is place
This root is the eminentia articularis, on which
the condyle, with its inter-articular cartilage, is"
thrown when the jaw is depressed. The pos-
terior root has itself two origins, which cit-
cumscribe the external auditory foramen’
and it flows into and joins the anterior, just
when that root is altering its direction. Be
tween the squamous process, and that part |
the zygomatic process which is between the

CRANIUM. ;

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CRANIUM. 735

two roots, there is a groove in which play
the posterior fibres of the temporal muscle.
The fossa articularis, which is between the
roots, is bounded behind by the Glasserian
fissure before mentioned; it forms, with the
adjoining fossa parotidea, the glenoid cavity.
The z atic process extends forwards about
an seuhaseie its anterior root ; being, therefore,
convex externally and concave internally. Its
upper border gives attachment to the temporal
fascia; its inferior (which is about half the
length of the superior) to the masseter muscle.
Its external surface is covered by the integu-
ment, and its internal forms the outer boun-
dary of the temporal fossa, in which is situ-
ated the temporal muscle. The extremity of
the zygomatic process forms a point, on account
of the under margin being bevelled and den-

‘ticulated to articulate with the malar bone.

The circumference of the squamous process
is sharp, in all that part which is above the
level of the zygomatic ee and denticu-
lated, at the expense of its outer table, in the
rest of its extent; so that it rests on the sphe-

noid bone.
The connexions of this bone and the me-

chanical effects which result from its position,

will be readily understood. Its petrous por-
tion being wedged between the basilar process
of the occipital bone, which serves it as a
fulcrum, and the ala major of the sphenoid,
which binds it against that fulcrum; the in-
ferior part of its squamous process resting on,
and being sustained by the sphenoid bone,
while its mastoid process is braced in by the
posterior inferior angle of the parietal, and by
the occipital bone—the fronting squamous
margin will effectually resist the lateral thrust
of the parietal; the more so that a limited
=e movement is allowed at the fulcrum.

e€ zygomatic process advancing forwards to
the malar bone, will, with its fellow of the
opposite side, give stability to the several
bones of the face; and, in common with the
pterygoid owtrmied of the sphenoid bone,
maintain the imtegrity of the various arches
which they form. It is also connected with
the lower jaw.

This bone is developed from six points of
ossification: viz. one for each of the three
great divisions, and one each for the zygomatic
and styloid processes and the auditory canal.
At birth it consists of four pieces, the squa-
mous (a), mastoid (c), petrous, and an in-

Fig, 374.

\

complete bony ring (d), to which the mem-
brane of the tympanum is attached. The
bony ring is the first to join, by its upper part,
the squamous; after which it is consolidated
with the petrous, and then extends itself out-
wards and backwards to form the meatus
auditorius externus, and all the four pieces are
then united. In infancy the bone sustains
great changes; the squamous process from
being straight becomes curved ; the zygomatic
process recedes from the squamous and in-
creases the space between them; the mastoid

rtion becomes more tumid, is developed
upwards and backwards, and sends forth the
nipple-like process which gives to it its name.
The eminentia articularis and fossa articularis
from an oblique assume a transverse direction,
and become, the one more concave, the other
more convex. The styloid process, though
ossified in its middle, is frequently, to an ad-
vanced age, connected with the bone by carti-
lage only.

The parietal bone (os parietale; Germ. die
Scheitelbeine oder Seitenbeine) (fig.372, 373 P)
constitutes with its fellow the greater portion
of the vault of the skull, and forms with it a
sort of bridge, the corners of which on each
side are fixed, the one on the great wing of
the sphenoid, the other on the mastoid process
of the temporal bone, the squamous process
of which braces in the intervening space.

The external surface offers in its centre a
prominence which marks the spot at which
ossification commenced; and it marks also
the widest part of the skull. Below this is a
semicircular line (the linea temporalis), to
which are attached the temporal fascia and
muscle; still more inferiorly is a plane surface
occupied by the temporal muscle; and_be-
tween it and the lower border, is a lunated
articular portion with cenverging strie, to- be
applied against the squamous portion of the
temporal bone. Near the posterior part of the
bone and a little removed from its upper border
is the foramen. parietale, for the passage of a
vein to the longitudinal sinus.

The inner surface exhibits the usual indi-
cations of the convolutions of the brain, and
also arborescent sulci, which mainly proceed
from the anterior inferior angle of the bone,
and are directed upwards and backwards to
the fossa parietalis, which answers to the pa-
rietal prominence on the outer surface; these
sulci lodge the branches of the middle menin-
geal artery.. Along the upper border is a de-
pression, which, with a similarly disposed edge
of the other bone, forms a groove for the
lodgement of the longitudinal sinus, and
hence is termed sulcus longitudinalis ; near to
it are sometimes seen small depressions (fosse
Pacchionii) for the granulations of the dura
mater, called glandule Pacchionii externe.

The borders are of various lengths; the
superior is the longest, the inferior is the
shortest, and the anterior is longer than the
posterior. The superior is united to the same
border of the opposite bone by the regular
interchange of serrations of the outer table ;

the anterior and posterior reverse the arrange-

736

ment which obtains in the frontal and occipital
bones; that is, they are overlapped in the
upper part, while in the lower they overlap
those bones ; the inferior is sharp, and merel
terminates the articular surface already al-
luded to.

The angles contained within these borders
are the frontal (which is nearly a right angle)
formed by the superior and anterior borders ;
the occipital (more obtuse) by the superior
and posterior borders; the mastoidal, truncated
and articulated with the mastoid process of the
temporal bone; and the spinous ae re-
ceived on the tip of the great wing of the
sphenoid, and intervening between the tem-
poral and frontal bones. The mastoidal angle
is, on its inner surface, traversed by a sulcus
(the sulcus lateralis) to lodge the lateral sinus
and to transmit it from the occipital to the
temporal bone. The spinous angle is deeply
grooved on its inner surface by the sulcus
x tao for the middle meningeal artery, or
the arteria spinalis dure matris; this groove
has its place frequently supplied by a canal,
then called canalis spinosus.

Its connexions are with its fellow above;
the temporal and sphenoid below; the frontal
before; and the occipital behind.

The parietal, like each half of the frontal
bone, is developed from the protuberance; and
from this point the ossific matter radiates to-
wards its several borders. While this process
is going on, the part above and the part below
the centre form a considerable angle with
each other; but this is much effaced when the
edges have arrived at their destination, espe-
cially when the squamous process of the tem-
poral quits its vertical for its curved position.

Articulation of the cranial bones.— These
several bones are locked together so as to form
the envelope of the brain, and the mode by
which their secure adherence to each other is
effected, differs in the summit, on the sides,
and in the base of the cranium.

In the calvaria they are united either by the
overlapping or by the dove-tailing of their
edges, or else by the two modes combined.
The inner table does not proceed so far as the
external, and the latter being jagged with pro-
cesses which have no definite form, but which
are either tortuous, or narrower at their fixed
than at their free extremity, the outer tables
are immovably joined by the fixation of the
processes of each side into the spaces of the
other. By this means the inner tables of the
two bones are brought nearly into contact,
a thin lamina only of cartilage intervening ;
so that on looking into the vault, but little
more than a plain line will be noticed. Here,
however, there is no overlapping of the outer
tables; but the only instance of it is in the
junction of the two parietals on the median
line, by which, in effect, they form but one
bone. On the sides of the skull there is a
mere overlapping of the descending by the
ascending portions, and to accomplish this,
and yet maintain uniformity of surface, those
parts of the outer tables which project beyond
the inner are pared off or thinned in opposite

CRANIUM.

directions. Thus the squamous p a
ope
sphenoid rise upwards from a fixed basisand =
form a wall which is bevelled off on the inner
edge of its outer plate, so as to receive the
parietal and frontal bones, the outside of
which sustains a corresponding bevelling, by
which arrangement they are prevented from
being thrust outwards. The articulation of
the anterior and the ior with the middle
portion of the calvaria, is a modification of
the two pepe that is, the outer table is

tly bevelled an wre denticulated. The
rontal and occipital bones are symmetrical
and single, while there are two parietal; and,
though these are well united by their mutual
interchange of denticulation, they are yet more
firmly consolidated by the extension of the
frontal and occipital bones on the frontal and
occipital angles of the parietals, and on their
borders to some distance from those angles ;
each symmetrical bone thereby forming a spe-
cies of cramp on the parietals. The edges,
however, of the outer tables are not pared to
a sharp ridge, but there is left sufficient to be
fashioned into processes to maintain the secu-
rity of the skull in a longitudinal direction.
The parietals being thus firmly secured above
and below, the intervening portion of their
edges is competent to act as girders themselves,
and, in fact, we find that the lower part of
their anterior and posterior borders overlap the
corresponding portions of the frontal and occi-
pital bones respectively.

In the base of the cranium the bones are
placed in simple contact, and are so disposed
that forces, descending from above, will neces-
sarily drive them closer to each other. To
understand this rightly, we must suppose the
sphenoid and occipital to form (which, in faet,
they do) but one bone at an early period of
life. The temporal bone is placed alongside
the occipital, in such a way that the petrous
process is wedged into the angle between the
basilar process of the occipital, and the great
wing of the sphenoid; while the latter, again,
is wedged into the angle between the petrous
and squamous processes of the temporal bone.
It has been said that on the upper surface of
the outer margin of the great wing, rests the
lower part of the squamous process ; in case
of force descending through the parietal bone
this will be the fulcrum, and the lever (the
squamous process) being directed outwards,
the mastoid and petrous processes will neces- _
sarily be a Bago 5 more forcibly against the —
occipital bone and its basilar process.

The peculiar appearance presented by the
articulations on the outer surface of the cal-_
varia, has procured for them the name of
sutures, a term which is applied frequently to
the joinings in the base, although they are
essentially different in appearance and in fact.
Those which are aaa in the calvaria, and
to which the name is more suitable, are the
coronal, lambdoidal, and sagittal sutures.

The coronal suture extends between the tv
great wings of the sphenoid bone across th
upper part of the skull, and connects the fron-—

CRANIUM.

tal to the two parietal bones (fig. 373, a).
The lambdoidal (0) consists of two diverging
lines formed by the articulation of the posterior
border of the two parietals with the superior
half of the occipital; and extends from the
superior to the lateral angles of that bone.
The sagittal is the line of union between the

ietals themselves, and runs longitudinally
fou the superior part of the lambdoidal to
the centre of the coronal suture. On each side
of the skull is the squamous suture (fig. 373,
é); it has none of the serrated characters of
the other sutures, but is an arched line ex-
tending from the great wing of the sphenoid
to the mastoid process of the temporal bone,
and traversing so much of the border of its
— process as embraces the parietal

The squamous suture and the lambdoidal
suture are connected by a short transverse line
formed by the articulation of the mastoid angle
of the parietal bone with the mastoid process
of the temporal, and which is called addita-
mentum suture squamose (fig. 373, g). From
the lateral angle of the occipital bone to its
jugular process, that is, from the termination
of the lambdoidal suture (where it is joined by
the before-mentioned supplement of the squa-
mous suture) to the jugular foramen, there is
a line formed by the posterior border of the
mastoid process and the occipital bone termed
additamentum suture lambdoidalis.

The transverse frontal suture (fig. 373, a)
is situated transversely, but forms several
angles in its course. It extends from one
external angular process of the frontal bone to
the other; commencing at either angle, after
uniting that angle to the malar bone, it enters
the orbit, and unites the frontal bone to the
great wing and to the small wing of the sphe-
noid ; it then passes out of the other side of
the orbit, joining the same bone to the eth-
moid, lachrymal, nasal process of the superior
maxillary and nasal bones themselves ; enters
the orbit of the opposite side and retires from
it, articulating the frontal to bones analogous
to those in the other orbit.

Other sutures are occasionally enumerated,
such as the sphenoidal, which entirely sur-
rounds the sphenoid bone; and the ethmoidal,
which a the cribriform plate of the eth-
moid bone. Both of these, so far as they
deserve the name of sutures, are comprehended
in the transverse frontal suture.

The articulations of the temporal with the
occipital, sphenoid, and parietal bones have
been designated as the petro-occipital, petro-
sphenoidal, spheno-temporal, and spheno-pari-
etal sutures; but, with the exception of the
last, (which is squamous, and truly a part of
that suture,) they are not sutures,

It ought further to be remarked that, while
the bones of the calvaria are much thinner
than those of the base, they are comparatively
thicker in their borders to allow of that serra-
tion from which the term suture is derived.

To study, in combination with each other,
the facts enumerated in the foregoing descri
tion, it is necessary to take a survey of the

737

external and internal surfaces of the skull
itself.

For this purpose the external surface may
be divided into four regions: the superior, the
inferior, and the two lateral.

The superior region extends from the nasal
process of the frontal bone to the occipital
i erat and is bounded on each side

y the linea temporalis; a curved line, which,
commencing at the external angular process
of the frontal bone, passes backwards, traverses
the parietal below its protuberance, and is re-
ceived on the extreme point of the root of the
zygomatic process of the temporal bone. To
iii from before to behind, there are, on

e median line, the nasal process and the
rough notch for the articulation of the nasal
bones; the nasal protuberance; the glabella
bounded laterally by the frontal processes; the
line indicating the junction of the two fetal
portions of the frontal bone; the centre of the
coronal suture; the whole length of the sa-
gittal suture, with the foramen parietale on
each side of it; the superior angle of the .
occipital bone; a part of the occipital bone
itself; and, lastly, the occipital protuberance.
Laterally, and on each side, there are the
frontal process, the superciliary ridge, the
depression between them, and the supra-or-
bitary foramen; the frontal protuberance ; the
coronal suture; the parietal protuberance; the
lambdoidal suture; and so much of the side
of the occipital bone as is above the transverse
ridge.

The inferior region extends from the pos-
terior part of the nasal process to the occipital
protuberance, and is circumscribed by a line,
continuous with the extremities of the supe-
rior curved ridge of the occipital bone, and
passing on the outside of the mastoid and in
the direction of the zygomatic process of the
temporal bone, to the crest which is on the
a har process of the great wing of the sphe-
noid. The facts to be here noticed are nu-
merous, and, to facilitate their enumeration,
this region may be divided into three parts,
one anterior to the pterygoid processes of the
sphenoid bone, one posterior to the articu-
lating processes of the occipital bone, and a
middle one between these two.

The anterior division contributes to form the
nose and the orbits. For the first, there may
be observed on the median line, the nasal
lamella of the ethmoid bone, articulated, in
front, to the nasal process of the frontal, and,
behind, to the crest in front of the body of the
sphenoid. On the same line, but below and
behind this, is the azygos process, and inferior
part of the body of the sphenoid, with the
channels to form, with the vomer, the palatine
canals. On either side of the nasal lamella is
the slit for the ethmoidal nerve and vessels ;
the cribriform plate and its foramina; and the
space which assists to form the nares. More
laterally, and still passing from before back-
wards, is the internal angular process of the
frontal bone, to unite with the lachrymal; the
cellular mass of the ethmoid, with its turbi-
nated processes on one of its sides, and the

738

orbitar plate on the other ; the junction of this
mass to the body of the sphenoid; the turbi-
nated process of the same bone, and, some-
times, the opening into its sinus; the articular
surface for the palate bone; and, lastly, the
base of the pterygoid process exhibiting the
anterior orifice of the Vidian canal.

Still more outwardly is the part which forms
the orbit, concave, and broader before than
behind. To the fore part there are, on the
outer side, the lachrymal fossa; on the inner
side the trochlear fossa, and, near to it, the
orbitar orifice of the supra-orbitary foramen.
Further back there is on the inner side a por-
tion of the transverse suture between the
frontal and ethmoidal bones, containing the
two internal orbitar foramina; and, te the
outer side, another portion of the same suture
between the frontal and sphenoid. A third,
shorter portion connects the two preceding,
and unites the frontal to the small wing of the
sphenoid. Behind this there are in succession
the foramen opticum; the foramen lacerum
orbitale superius; the foramen rotundum ;
and, lastly, the sulcus temporalis leading from
the last foramen, and being behind the orbitar
process of the sphenoid bone.

The middle division offers in its centre the
basilar process of the occipital bone, and the
line of its junction with the sphenoid. On it
are seen the indications of the attachment of
the pharyngeal and anterior recti muscles.
Its posterior edge forms a segment of a circle
to assist in forming the foramen magnum.
On either side, and from before backwards,
are the external and internal pterygoid pro-
cesses, with the fossa navicularis, fossa ptery-
goidea, and hiatus palatinus between the two
processes; the posterior orifice of the Vidian
canal; the foramen lacerum anterius; the
under surface of the petrous process of the
temporal bone, with, on one side, the line of
its junction with the basilar process, and, on
the other, the line of its junction with the
sphenoid bone, the Eustachian sulcus occu-
pying the latter; behind the foramen lacerum
anterius is the rough surface for the origin of
the levator palati and tensor tympani muscles ;
the inferior orifice of the carotid canal; the
opening of the aqueduct of the cochlea; and,
lastly, the foramen lacerum posterius. More
outwardly, and pursuing the same direction,
are the under surface of the great wing of the
sphenoid bone; its line of union with the
temporal ; the processus articularis ; the fossa
articularis; the Glasserian fissure; the fossa
parotidea ; and, lastly, the rough inferior bor-
der of the foramen auditorium externum. On
the inner edge of this plane, and to the outer
side of the sulcus Eustachianus, there are,
successively, the foramen ovale; the foramen
spinale; the styloid process; the spinous pro-
cess, which is wedged into the Glasserian fis-
sure; the crest between the fossa parotidea
and the foramen lacerum posterius ; the vagi-
nal process and the styloid process.

The posterior division exhibits, on the me-
dian line, the foramen magnum; the longi-
tudinal spine bisecting the inferior curved

CRANIUM.

ridge, and having, on each side, below that
ridge, rough depressions for the attachment
of the posterior reeti muscles, and above that
ridge, still stronger and larger marks of the
attachment of the complexus ; and, lastly, the
inferior aspect of the occipital protuberance.
To the extreme outside and passing from behind
forwards, there are the termination of the
superior occipital ridge; the additamentum —
suture lambdoidalis ; the posterior part of the
mastoid portion of the temporal bone dis-
playing the foramen mastoideum ; the sulcus
occipitalis on one hand, the mammillary pro-
cess of the mastoid portion of the temporal
bone on the other, and the sulcus digastricus
between the two; and, lastly, the foramen
stylo-mastoideum at the bottom of the sulcus
digastricus. Midway, and between the me-
dian and outer portions of this region, and still
passing from behind forwards, there are, the
Superior occipital ridge, the inferior occipital
ridge, and between them the marks of the
attachment of the splenius capitis and trachelo-
mastoideus; the oblique surface into which
the obliquus capitis superior is inserted ; the
posterior condyloid fossa, containing the pos-
terior condyloid foramen whenever it exists;
the condyle itself; the anterior condyloid fossa
and foramen; and, lastly, to the outside of the
condyle, the processus lateralis.

The lateral region (fig. 373) is oval, and its
boundaries have already been stated. Its sur-
face, lengthwise, is undulated, being convex
behind, where the temporal and parietal form it;
and concave in front, where the temporal and
sphenoidal enter into its composition. Pro-
ceeding from above downwards, and com-
mencing with the linea temporalis, we have
so much of the parietal and frontal bones as
are below that line, with the inferior extremity
of the coronal suture between them; next,
the sutura squamosa between the parietal and
temporal bones, and part of the transverse
suture between the frontal and sphenoid ;
below this, the squamous process of the tem-
poral bone, and, in front of it, the temporal
process of the sphenoid with the line of arti-
culation between them. These parts form the
fossa temporalis, which is limited inferiorly,
on the sphenoid by a crest which divides it
from the jugal fossa belonging to the face, and
on the temporal by a groove on the upper part
of the two roots of the zygomatic process, in
which play the posterior horizontal fibres of
the temporal muscle. Passing from behind
forwards, there will be observed at the lower
boundary of this region, the additamentum
Suture squamose; the base of the mastoid
process; the foramen auditorium externum ;
and, lastly, the zygomatic process of the tem-
poral bone articulating anteriorly with the
malar bone.

The interior of the cranium presents through-
Out its entire extent more or less evidence of
the adaptation of its surface to the convolutions
of the brain.

The base is bounded, in front by the fora-
men coecum; behind, by the centre of the
internal crucial spine; and, in its circumfe-

toa wr

LYSINE sc, il | Sa Ad in ch ANA i Ral al dh LEAs i dd dR. 3 BE oe Ow

CRANIUM. 739

rence, by a line passing on each side along
the outer border of the orbitar process of the
frontal bone, the junction of the parietal and
sphenoid; the parietal and temporal bones; and
the lateral limb of the internal crucial spine of
the occipital.

It is placed obliquely downwards and back-
wards, and consists of three principal divisions
or platforms—the posterior being the lowest,
the anterior the highest; and the middle, on a
plane between the two.

The anterior division is called the anterior

fosse@, and sustains the anterior lobes of the
brain. It is concave in the middle and con-
vex on each side; it is limited, anteriorly by
the merging of the orbitar processes into the
general mass of the frontal bone, and poste-
riorly by the posterior margin of the ale mi-
nores. On the median line, from before back-
wards, we encounter the foramen ceecum; the
crista galli; the ethmoidal process of the
sphenoid bone; and, lastly, the smooth sur-
face of that bone on which the olfactory nerves
repose. On either side of the crista galli is
the processus cribrosus, with its foramina, and
slit for the ethmoidal nerve and vessels ; more
outwardly, is the transverse suture uniting this
process to the frontal bone, and in it may be
seen the internal orifice of the anterior internal
orbitar foramen. From hence outwards, is the
orbitar process of the frontal bone, somewhat
arched, and displaying, more evidently than
in the rest of the skull, the digital impressions
of the brain; behind this is the transverse
suture uniting it to the small wings of the
sphenoid bone; and, lastly, there is the upper
surface of the small wings themselves.

The middle fosse consist of two large fossz
laterally, and one, which is smaller, centrally.
This latter is the pituitary fossa; in its front
is the olivary, and, behind it, is the basilar
process ; on its sides are the sulci carotici, and
its corners are bounded by the ephippial or
clinoid processes. In front of the olivary
process is the groove on which the optic nerves
decussate; and between it and the anterior
ephippial processes of each side is the foramen
opticum.

The lateral fossee are very deep and of an
iregular triangular figure, the base of which
is directed outwards. Anteriorly they are
bounded by the small wings of the npr
bone, and posteriorly by the ridge which se-
parates the cerebral from the cerebellar surface
of the petrous portion of the temporal bone.
Each is formed, anteriorly and internally, by
the great wing of the sphenoid ; posteriorly,
by the cerebral surface of the petrous process ;
and, externally, by the squamous process of
the temporal bone. In it are seen the lines of
junction between these parts, and the sulci
formed by the spinous artery of the dura mater.
At its anterior boundary there is the foramen
lacerum orbitale superius; and behind it,
inclining gradually outwards, there are in suc-
cession, the foramen rotundum, the foramen
ovale, the foramen spinale, the sulcus Vidi-
anus, the hiatus Fallopii, the depression for

the Gasserian ganglion, and the processus semi-
circularis. To the inner side of this range,
and ona level with the foramen ovale, is the
foramen lacerum anterius.

The posterior division extends from the
basilar process of the sphenoid bone to the
internal tubercle of the occiput. Its margin
is of a triangular figure, with its base curved
and directed backwards. The petrosal ridges
form the sides of the triangle, and the lateral
limbs of the internal crucial spine, its base.
On the median line and passing backwards
we observe the superior sulcated surface of the
basilar process, with a groove on each side for
the basilar sinus; the foramen magnum with
the anterior condyloid foramina near its ante-
rior part; and, lastly, the inferior limb of the
internal crucial spine, separating the two
great cerebellar fosse. Each of the latter is
bounded, above and to the outside, by a
broad groove for the lateral sinus, which
groove passes from the occipital bone to the
mastoid angle of the parietal, from thence to
the mastoid process of the temporal (where
the mastoid foramen opens into it), and, ulti-
mately, to the occipital bone again, where it
turns forwards to the foramen lacerum pos-
terius. In this groove is seen the termination of
the lambdoidal suture, and the additamentum
suture squamose and the additamentum su-
turee lambdoidalis cross it; the principal
portion of the latter being seen in the cere-
bellar fossa. Anteriorly, and above the fora-
men lacerum posterius, 1s the cerebellar surface
of the petrous process of the temporal bone ;
exhibiting the openings of the meatus audi-
torius internus and of the aqueduct of the
vestibule; and, on the ridge which separates
this from the cerebral surface, the groove for
the petrosal sinus.

The calvaria possesses in its centre a dense
curved rib, which extends through the roof
from the anterior to the posterior part of the
base, but which is more evident at its extre-
mities than in its middle, where it is generally
marked by a groove for the longitudinal sinus.
The frontal spine commences it, and its ter-
mination is the superior limb of the internal
crucial spine; the intermediate portion (where
it is masked) is the sagittal suture. On each
side, and from before backwards, we notice
in succession the frontal depression ; the coro-
nal suture; the parietal depression, and several
arterial sulci running towards it from below ;
part of the lambdoidal suture; and, lastly,
the cerebral fossa of the occipital bone. On
each side of the sagittal suture are the fossx
Pacchioni, and, near its back part, the foramen
parietale.

A comparison of the external and internal
surfaces of the cranium establishes the fact
that there is a general correspondence of the
two as far as regards those parts which are in
contact with the periphery of the brain. But,
between the several divisions of that organ,
there are developed on the inside of the skull
very large ribs and processes which destroy the
particular correspondence of the two surfaces.

740

Nevertheless, this does not impair our ability
to deduce the internal capacity of the cranium
from an examination of its exterior; since the
diploe between the two plates, in the spaces
intermediate to these ribs, seldom varies more
than one or two lines in its thickness.

In a skull of ordinary capacity, the length,
measuring from the frontal spine to the longi-
tudinal suleus, is five inches and a half; its
width, between the bases of the petrous pro-
cesses of the temporal bones, four inches and
a half; between the parietal fosse, five inches ;
and between the extremities of the ale mi-
nores, three inches and three quarters: its
depth, from the foramen magnum, four inches
and a half, from the ephippium three inches
and a quarter; and, from the front of the
olivary process, two inches and three quarters,
But observation proves to us that there is little
dependence to be placed on these measure-
ments ; scarcely any two skulls agree in their
diameters, for where one exceeds in a given
direction, it may fall short in some other. To
this conclusion we shall be led by the ex-
amination of skulls, not only ef members of
the same community but even of persons con-
nected by the closest ties of consanguinity,
While, however, there is any doubt about the
matter, it is not to mixed communities we
should have recourse in our search for facts ;
but rather to the well-authenticated skulls of
such tribes as inhabit parts of the globe re-
mote from each other, and whose manners and
customs have, to the best of our belief, re-
mained stationary from time immemorial; for
by this procedure we shall avoid the confusion
arising from a mixture of different races of
men whose respective dispositions have been
modified by intermarriage.

The skulls of a North American Indian and
a Hindoo will be good examples to shew how
the diameters will vary. By making a longi-
tudinal section of each, we shall find, by ap-
plying a line between a spot about five-eighths
of an inch above the root of the nose, and
another about three-eighths of an inch above
the superior angle of the occipital bone, that
there is considerably more space above the line
in the Hindoo than there is in the American
Indian, while the distance to the foramen
magnum is much greater in the latter than in
the former. Again, if we make the usual ho-
rizontal section, it will be manifest that in
breadth the Indian will exceed the Hindoo
by nearly, and, sometimes, more than an inch,
although the latter has the advantage in length.

In the Negro, which, in length, is equal to
the Hindoo, the space above the line in a
vertical section is not absolutely, much less
relatively, so great towards the frontal bone
as in the shorter skull of the Indian; while
towards the posterior part of the parietals it is
much greater, and in its breadth it falls but
little short of it.

These three aboriginal types will suffice to
shew the endless varieties which must prevail
in mixed communities, and to. satisfy us that
the forms of skulls are as numerous as the

CRANIUM.

diversified modifications of character with
which the Creator has endowed the human race.

Several naturalists have sought to establish
an analogy between the cranium and the ver-
tebre, and have imagined that they had dis-
covered in the one a type of the other; in
Other words, that the cranium is neither more
nor less than a gigantic vertebra which has been
submitted to some necessary modifications.

In this sense the ephippium and basilar por-
tion of the occipital bone represent the body
of a vertebra; the foramen magnum, the ver-
tebral foramen; the longitudinal spine of the
oncigaeet bone, the spinous process; the ex-
panded portion of the bone as far asthe mas-
toid portion of the temporals, the vertebral
plates ; the mastoid processes themselves, the
transverse processes; the eminence above the
anterior condyloid foramina and the condyles
themselves, the superior and inferior oblique
processes; and the notch behind the condyles
and the jugular notch, the notches which form
the conjugal foramina.*

Others again regard the cranium as com-
posed of several vertebree more or less com-
plete, which are so associated as to meet the
exigencies of the highly developed summit of
the medulla spinalis. The resemblance, how-
ever, of many of the parts to a vertebra is so
imperfect as to admit of the greatest license, .
as respects both the fixing of the number and
the apportioning of the parts which severally
belong to them. The alteration of position, .
too, to which they are necessarily subject to
enable them.to accord with the change in diree-
tion which the nervous matter sustains, casts
much confusion on the subject, and prevents
the mind from recognizing, at once, a similarity
which would be more apparent if they con-
tinued to be superimposed on each other as
they are in the spine instead of being arranged
at right angles with it.

The occipital bone certainly offers no dif-
ficulty to the detection of an analogy between
it and a vertebra; and we readily discern in it
a body; a foramen; two transverse, four arti-
cular, and one spinous process; and four
notches. These have already been pointed
out, and it is sufficient here to observe, that,
in this bone apart from the others, the basilar
process alone will represent the body, and the
lateral processes will be the type of the trans-
verse processes of the vertebra.

By removing the bones of the face and
taking the sphenoid in conjunction with the
frontal bone, we shall (if we place the body

'
a ee ee ene ee eee

* This was Dumeril’s theory.—See Consid. gén.
sur l’Analogie entre tous les os et les muscles du
tronc des animaux. ~- Magasin Encyclopédique,
1808, t. iii. |

+ The celebrated Goéthe was among the first to
adopt this idea. He admitted the existence of
three vertebre in the cranium, (Zur Naturwis- —
senschaft tiberhaupt, &c. Stuttg. 1817-24.) The —
further development of it occupied the oer
of O’Ken, Spix, Meckel, Geoffroy St. Hilaire, and —
Carus.—See Meckel, Anat. Desc. &c. t. i. p. 631, —
and Carus, Anat. Comp. par Jourdain, t. iii.
Taotroduction.—Ep.” : a

ppt SAL a ati ah A a) CES Al A MB A tl Pa hk eh Me en

Pee OT eee ey set etree) We Wee eT

CRANIUM. 741

of the sphenoid bone vertically) at once per-
ceive the same analogy to exist. If, when

_ they are thus placed, we look at the cerebral

surface, we shall recognize the body in that of
the sphenoid ; the vertebral plates in the small
wings of the sphenoid, and two halves of the
frontal bone; the foramen in the space cir-
cumscribed by these last; the transverse
processes in the two great wings of the sphe-
noid; and the notches in the lacerated orbitar
foramina, and the angles between the body of
the sphenoid and posterior margin of its great
wings. If we look at it in front, it will not
require any great stretch of the imagination
to recognize the four articulating processes in
the pterygoid processes of the sphenoid bone
and the external angular processes of the
frontal.

The temporal and the parietal bones toge-
ther represent another vertebra, situated be-
tween the former two. By looking at the
base of the skull held vertically, and abstract-
ing in the mind the occipital bone, we can
(under favour of the license allowed to, or
taken by anatomists) see in the two petrous
anlecey of the temporal ‘bones, if they were

rought into contact, a type of the body of a
vertebra; and in those parts of them which
contribute to form the anterior and posterior
lacerated foramina, we observe a resemblance
to those notches which form in the vertebre,
as they do here, conjugal foramina. The arti-
cular eminences of the temporal bones give
us no bad notion of the transverse processes,
while the zygomatic processes above (still
holding the skull vertically) and the part
which projects behind the mastoid processes
below, will indicate the four oblique or arti-
culating processes. Lastly, the squamous pro-
cesses of the temporal and the whole of the
parietal bones represent the vertebral plates,
and the space enclosed by them, the vertebral

foramen.

Development of the cranial bones.— The
progressive development of the bones of the
cranium has been pointed out in their separate
descriptions; but there are some general facts
which regard its formation as an entire organ
which merit further notice.

The cranium of the foetus presents, like all

other organs, a rude outline of the shape it is

destined to assume; and, at the earliest pe-
riod at which it is noticed, its walls are com-

pletely membranous, being formed by the dura
‘Mater and pericranium so united as to render

it impossible to separate them without injury.
Very early points of ossification are developed
in this membranous envelope, whence osseous
radii shoot out, so that the several points

enlarge towards each other, and ultimately
coalesce or are united by suture.

Unlike other bones of a similar character

the opposite surfaces are not of similar den-

sity. e surface secreted by the vessels of
the dura mater contains less animal matter
than that which is produced from the vessels
of the pericranium ; and it is, therefore, of a

more dense and brittle character; so much so,

that, when the contiguous bones approximate,
the edges of the inner table are simply in
Juxta-position, a slight layer of cartilage alone
separating them. Hence, in the interior of the
skull, the sutures are plain lines ; or, if at all
irregular, there is no interchange of substance
between them. Not so, however, with the
external. By reason of the greater quantity
of animal matter which it possesses, and the
more diffuse character of its texture, a prin-
ciple of toughness is conferred on it which
admits of its being dove-tailed with the same
table of other bones.

The base takes precedence of the calvaria
in the commencement and completion of its
ossification. With the exception of its most
prominent points, and the ethmoid bone, it is
completely ossified at birth; while, between
the bones of the calvaria, there are conside-
rable membranous interspaces, so as to allow
of these bones being squeezed together, or to
overlap each other, at the period of parturition.
The ossific matter departing from the pro-
tuberances of the frontal and parietal bones
(c,d, figs. 374,375)
and radiating to-
wards the circum-
ference of these
bones, it follows
that the angles
will be incomplete
when the rest of
the bone is formed.
On this account it
is that, at the four
angles of each pa-
rietal bone, there
is a membranous spot which the ossific matter
has not reached, when, in other parts, it is
joined to the surrounding bones. These
spaces are called fontanelles ; two of them are
situated on the median line and superiorly ;
and two others inferiorly and in each lateral
region. The posterior superior fontanelle is
triangular, and is found between the superior
angle of the occipital bone, and the occipital
angles of the two parietal. The anterior
superior fontanelle (a,
jig. 376), by reason of
the frontal bone being
formed in two parts, is
of a lozenge shape; and
it is between those two
parts and the frontal an- §) .
gles of the parietal bones ¥j\
that it occurs. These two Wi
fontanelles are conse-
quently at the extremities
of the sagittal suture.
The inferior fontanelles
are found, the anterior (a, fig. 375) between
the spinous angle of the parietal, and the great
wing of the sphenoid bone; the posterior
(b, fig. 375) between the mastoid angle of the
first-named bone and the mastoid process of
the temporal. These two fontanelles are,
therefore, situated at the extremities of the
Squamous suture.

742

Tn infancy the rela-
tive proportion of the
cranium to the face is
much greater than in
adult life; and this
causes the foramen
magnum to appear to be
situated much further
forward, in the infe-
rior region of the base,
than it is when the
face is niore expanded.
The lower part of the occiput is flattened, the
Superior is very projecting, and, altogether,
the cranium has a character of rotundity which
is speedily exchanged for the oval form which
prevails in the adolescent age.

When the sutures have become conjoined,
and the cranium is constituted a defensive in-
vestment of the brain in virtue of its mechan-
ism, the internal table (the tabula vitrea) is
secreted in greater abundance, and the diplde
between it and the outer table is rendered more
manifest. The spongy tissue of the sphenoid
bone is absorbed and the sinuses formed ; but
it is not until a period nearly coeval with
puberty, that those of the frontal bone are
developed.

It is not until the diplée is fully formed that
we can demonstrate those venous canals with
which that structure has been shown to abound
by the researches of Chaussier, Dupuytren,
and Breschet (figs. 187, 188, p. 436).

Mechanical adaptation of the cranium.—It
will now be noticed that the properties of the
cranium, those on which its defensive qualities
are founded, differ in the several periods of
life; but that, nevertheless, there is in each
as perfect an adaptation of it to these purposes
as seems consistent with the schemes of Provi-
dence in the creation of a finite being.

The pressure which the brain has to sustain
during the process of parturition, is directed
solely to that part which is not essential to life ;
the condition of the bones of the calvaria ad-
mits of the volume of the hemispheres being
diminished at the time the foetus is ushered
into the world. Not so the base; the parts
which it is destined to protect require to be
maintained in all their integrity, and the ex-
tent to which it has acquired solidity is such
as to forbid the encroachment of the parietes on
parts which are essential to the continuance of
life, and which are -highly intolerant of pres-
sure.

In infantile life, also, protection is afforded
on the same principle. The bones of the
calvaria are notoriously capable of sustaining
indentations, and afterwards, by their resili-
ency, of regaining their normal form. The
preponderance, too, of the organic over the
inorganic texture, blunts the force which may
be applied, and resists its transmission to the
parts below. But there is an addition even to
these provisions, a mechanical disposition of
the bones highly favourable to resistance. At
the back, on the sides, and in front—opposed
in every direction from which force may pro-

Fig. 377,

CRANIUM.

ceed—are the summits of ovoidal domes, and,
as the ossific matter radiates from these summits
to the circumference, the force will be received
on one extremity of a bundle of diverging
lines, and that which would sever the structure
if it fell on any other point, here falls compa~-
ratively innoxious. Hence it is that the cen-
ters of ossification are so much more projecting —
during infancy than in after life; for, although
the mechanical contrivance abides through the
whole term of existence, it is not, when asso-
ciated with other means, of that predominating
character which we observe in youth.

The manner in which the cranium (when
fully formed) defends the brain, differs widely
from the preceding. In proportion as its
several parts become consolidated, and the
relation between its animal and earthy consti-
tuents is reversed, so its power of deadening
or neutralizing the vibrations which pass through
it, is diminished. It is here on its general
shape and the disposition of its parts that its
protective properties depend.

It has been already stated that the bones of
the cranium are so fashioned as to concur in
the production of an egg-like cavity; and that
their margins are so arranged as to enable them
to bind and be bound by each other, in such
a manner that if one bone be taken away the
whole will have a tendency to separate. This
ovoid form ensures (much better than any
other which has no fixed basis or point of
resistance beyond itself) the transmission of
the vibrations which are distributed from any
spot on which force may be applied.

Assuming that the skull involved the pro-
perties of an arch, its defensive power has by
some been attributed to the circumstance of its
being of that figure. An arched form, how-
ever, would serve it only in the case of force
descending from above; it would not provide
resistance to those severe shocks which are
communicated from below, as in jumping,
nor protect it from blows that might arrive on
its sides.

But the cranium is not an arch, for there are
neither piers on which the extremities of that
arch could rest, nor abutments to resist their
lateral thrust. Supposing a barrel to be sawed
lengthwise, and the edges to be connected by
a base, if the centre be applied on a column,
(the proportion of which to the base is the
same as that of the spine to the width of the
skull,) it is manifest that, since the extremities
of the arch are received on the ends of two
long levers which have a common fulcrum, an
inconsiderable force would have a tendency to
sever them at their junction. On the other
hand, if the barrel were entire, force would be
transmitted through the parietes to a point
exactly opposite to that on which it impinged,
if it were not dissipated in its transit. Such
a degree of force however might be applied,
that its vibrations, distributed at the moment _

of its application, might pass through the entire a
walls, and, accumulating at one spot, by their %

intensity cause the fracture of the part. The —
natural mode of providing against this oceur-

ee

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wr le ei lll i a CER a ls lle AES ow lb oe lk a kts he ct Ea Lem

Peer rihiey ss. Pita wee | SE eet os

CRANIUM. 743

rence would be to strengthen the part in which
(from the situation of the organ) these vibra-
tions might, in general, be expected to concur ;
and this is the contrivance adopted in the cra-
nium, for in the centre of its base there is a qua-
drilateral portion (the body of the sphenoid
bone) of characteristic massiveness and strength.

It does not however augment uniformly in
its substance from above downwards. The
matter is accumulated in dense lines or ribs,
which pass to a common centre, and constitute
thereby a peculiar skeleton or frame-work of
surpassing strength, which admits of the intro-
duction of a lighter and more fragile structure
in the intervening spaces, and resists the shocks
that arrive through the spine, from behind or

‘from above.

_ This frame-work is situated almost entirely
in the base; the only part which is in the
calvarium being a longitudinal curved line,
formed by the ethmoidal process of the sphe-
noid bone, the crista galli of the ethmoid, the
spine of the frontal, the thickened commutual
margins of the parietals, and the superior limb
of the internal occipital spine. Independently
of this curved rib, the calvarium consists of
four ovoidal domes, two on each side; formed,
the anterior by the corresponding half of the
frontal bone, and the posterior by the parietal.
The summits of these domes are their centres
of ossification, and their bases abut, partly on
the longitudinal rib, and partly on the frame-
work in the base.

The part to which all the forces tend is the
body of thesphenoid bone. From its posterior
corners there pass backwards two ribs, (the
petrous processes of the temporal bones,)
which terminate on the extremities of an arch,
(the lateral limbs of the internal crucial spine
of the oceiput,) which is placed horizontally,
and the convexity of which is turned back-
wards.

This arch and the two ribs which connect it
to the centre are in the line in which the oc-
ciput would strike the ground in falling back-
wards; and they further form the brim of the
pit which contains the cerebellum, so that the
vibrations of force pass in the interstice between
that organ and the cerebrum.

From each side of the body of the sphenoid
bone there stretches forwards, outwards, and
re towards the temples, a curved rib,
{the anterior part of the great wing,) and, from
the anterior part of the body, a transverse rib
which overlays the former. These and the
posterior lateral ribs, all of which depart from
a common centre, constitute the frame-work of
the base which sustains the ovoidal domes of
the calvaria. The frontal dome is placed with
its summit (the frontal depression) looking
backwards, downwards, and inwards; its mar-
gin is received, inferiorly on the whole length
of the anterior transverse, and on the extremity
of the anterior lateral curved rib; towards the
middle line, on so much of the longitudinal
rib as extends to the parietal bones ; and supe-
riorly, it is applied against a portion of the
base of the parietal dome. It is against these
parts that it thrusts, whenever it receives a

shock on its summit. The parietal dome is
pare with its summit (the parietal depression)
ooking downwards and inwards. Below, it
is received on the extremities of the lateral
ribs; above, it thrusts against the remainder of
the longitudinal rib; behind, it falls on the
corresponding portion of the horizontal arch ;
and, in front, it antagonizes the frontal.

It is by the bases of these domes thus
thrusting against a solid frame-work, that the
cranium is endowed with the power of re-
sisting lateral shocks whether they approach
from before or behind ; and it is not, as some
allege, simply by the mobility of the head,
that it withstands blows, which, if it were
fixed, would fracture it.

There yet remains to be noticed an impor-
tant part of this skeleton or frame-work ; that
which bears upon the spine, and resists the
force transmitted through it. At the bottom of
the pit containing the cerebellum, there is an
elliptical opening (the foramen magnum), the
margin of which is very dense; this opening is
provided underneath with two tubercles (the
articulating processes), by which it rests on the
vertebral column; from these tubercles a curved
rib on each side (the lateral process of the oc-
cipital bone and the mastoid of the temporal)
extends upwards and outwards to the extremity
of the posterior lateral rib; the segment of the
margin of the opening which is anterior to the
tubercles, is prolonged upwards and forwards,
in the form of a broad pillar (the basilar pro-
cess), to the back part of the common centre;
the segment which is behind the tubercles
sends off, at its back part, a spine (the inferior
limb of the internal crucial spine), which ends
at the centre of the horizontal arch, at the point
where the superior longitudinal rib terminates ;
and this point of confluence of the forces from
below, from above, and from behind, is strength-
ened by a nodule (the internal occipital protu-
berance). The frame-work of the cerebellar
cavity is thus connected with that of the general
cavity; anteriorly, to the body of the sphenoid
bone; posteriorly, to the tubercle of the occi-
pital; and, laterally, to the extremities of the
petrous processes of the temporal bones. In
both of them it will be seen that they occupy
spaces between the grand divisions of the ner-
vous matter, which latter is, therefore, removed
from the chance of sustaining injury by shocks,
much more completely than it could have been
had the parietes been submitted to a progres-
sive augmentation of substance from above
downwards. As itis, the spaces in which the
nervous matter reposes are thin and frequently
diaphanous ; and, were they situated in un-
protected parts, would be perforated by the
slightest force.

During a considerable period of life the sus-
ject enjoys additional protection from the slight
yielding of the bones, and from the cartilage
which intervenes especially at the base. Pres-
sure applied on the vertex would tend to disjoin
the parietal bones from each other, and from
the frontal and occipital bones. This the pe-
culiar nature of the articulations forbids, and
the longitudinal rib chiefly, and the expanded

744
portion of the bones themselves in part, convey
the force downwards, the former forwards
through the median line of the ethmoid to the
front of the sphenoid, and backwards through
the superior and inferior limbs of the crucial
spine of the occiput, traversing the foramen
magnum, and passing through the basilar
process to the back of the sphenoid bone:
the latter forwards through the frontal bone
to the small and great wings, and, through
them, to the body of the sphenoid; and
backwards through the parietal and occipital
to the lateral limbs of the crucial spine.
The parietals convey it down the sides to
the great wing of the sphenoid and the mas-
toid process of the temporal bone, from which
it is transmitted to the common centre; and
the slight rotation which is permitted to the
temporal bone, (and which has already been
alluded to,) materially tends to break the force
in its transit. Nor is there any imperfection in
this apparent inclination of the parietals to an
outward divergence, for the squamous process
of the temporal bone which overlaps each be-
tween its two fixed points is strongly supported
On its outer side by the temporal muscle.

ABNORMAL CONDITIONS OF THE CRANIUM.

Most of the abnormal conditions of the cra-
nium are dependent on circumstances con-
nected with the evolution of the brain, and
are mostly acquired after birth; the only con-
genital variations being those in which there is
a total or a partial privation of its parietes.

There is no vestige of it, or, indeed, of the
head itself, in the true acephalous foetus; but,
whenever the medulla oblongata is present, the
base of the cranium is developed, and often-
times there are found rudimentary portions of
the other bones (false acephalia and anence-
phalia).

The parietal or occipital bones, and some-
times all of them are imperfect in that mal-
formation termed encephalocele, which, in
some cases, is analogous to spina bifida, and,
in others, to hernia cerebri. When serous fluid
constitutes the tumour, the deficiency of the
bones is considerable, owing to the arrestation
of the formative process; but when the brain
protrudes, their development continues in such
a way as to embrace the root of the tumour, and
then the calvaria, flattened and in contact with
the base, exhibits an opening through which
the hernia escaped.

The cranium is said to be, at times, insuffi-
ciently evolved; the evolution of its parts being
accelerated and their coalescence prematurely
effected, so that the ossific capsule is formed
before the brain has attained its full growth.
It is, however, most probable that in this as in
other cases it adapts itself to the brain, and
that it is on an imperfect development of that
organ that the smallness of the cranium is de-
pendent ; but varieties of this description which
are connected with deficiences of mental en-
dowment will scarcely admit of enumeration.

The parietes of the cranium may be preter-
naturally thin, without this being dependent on
disease; but they are most obviously in that

CRANIUM.

condition in hydrocephalus, in which affection,
however, there are two opposite states of the
skull. . sind -.

When the disease occurs in infancy, and
persists for any length of time, the bones of
the calvaria usually become thin and pellucid ;
the spaces between them are of great extent; _
and the deposition of the inorganic texture
is arrested in such a way that instead of
bones we have frequently litthe more than a
membrano - cartilaginous lamina, and some-
times not even that; for instances have been
known in which the upper part of the head
has been covered by membrane only. This
suspension of action, however, is in some
instances only temporary. The deposition of
ossific matter becomes then more rapid and
abundant than under ordinary circumstances ;
the points of deposit are more numerous. than
usual; and a skull of gigantic dimensions and
of peculiar and premature hardness is pro-
duced.

It has been sufficiently explained that the
several ossific elements of the cranium unite in
definite numbers to produce the bones which
we have been occupied in describing. Never-
theless, it not unusually happens that some of
these elements, or, otherwise, adventitious de-
posits of a similar character, which manifest
themselves, do not flow into and combine
with the other elements of the bone in which
they occur ; but, on the contrary, each in itself
forms the centre of an ossific process, and the
bone thus formed (be it large or small) articu-
lates by its circumference to the parts with
which it comes into contact. These adven-
titious pieces are commonly known under the
name of ossa Wormiana, because it is supposed
that they were first described by Wormius, a
physician at Copenhagen in the seventeenth
century ;* they are also called ossa triquetra,
triangularia, ossa suturarum, ossa supranume-
raria. They vary in situation, number, and
size. In general they are situated in the
lambdoidal suture; they are, however, met with
in the sagittal, occasionally in the coronal, and
(though rarely) in the squamous suture. One
of the most remarkable is that which sometimes |
replaces the superior angle of the occipital :
bone, called by Blasius os triangulare or epac-
tate. Bertin describes one in the situation of
the anterior fontanelle.

It is by a process analogous to the pre-
ceding that the occipital bone occasionally
presents a suture between the upper and under
halves of its posterior portion. The elements
of those two parts combine among themselves,
and the pieces resulting from their union ap-
proach, and, instead of forming the continuous
bone, as we usually see it, they are associated
by means of an additional suture.

An anomaly of not very unusual occurrence —
is the permanence of the suture uniting the —
two halves of the frontal bone, and which is —
seldom apparent beyond the second year of —
extra-uterine life. ah

>

4s

* Vid. Ol; Wormii-etvad. eam weetorent vienna
epistolx, t. i, Hafnie, 1728. a

CRANIUM.

There are but few skulls which are perfectly
symmetrical, although the variation of one side
from the other is generally so slight that the eye
does not at once detect it. In numerous cases,
however, the want of symmetry forcibly obtrudes
itself; sometimes one half is considerably larger
than the other; and in other cases it appears
to be thrown out of position, as though, during
the time that the parietes were soft, pressure
had been applied in front and behind, and, by
a sort of rotatory movement, it had been drawn
back on one side and pushed forward on the
opposite. There does not appear to be an
octane uniformity among the skulls of this
description saving that the projections are
always situated diagonally with respect to each
other ; that is, if it be twisted to the right, the
right half of the frontal bone will be in advance
of the left; while the posterior part of the left
parietal, and the corresponding side of the
occipital bone, will project behind the right.
This is by far the most prevalent variation, but,
occasionally, the left half of the frontal bone is
in advance, and, in such instances, the posterior
increase will be on the right side.

The change which takes place in advanced
age can scarcely be accounted ananomaly. At
that period the skull is much more an entire
bone than it is in the earlier epochs. The
sutures are to a certain extent effaced, and a
mere line indicates the former disjunction of
the bones. It is on the interior of the skull
that these sutures are first effaced, and on the
exterior the order of obliteration is from the
summit to the base. It has been affirmed that
the volume of the skull diminishes in old age,
and that it is susceptible of change, in different
directions, after the bones are locked together.
It is, however, certain that its external con-
figuration is somewhat altered, for the promi-
nences formed by the centres of ossification of
the parietal and frontal bones become flattened
and undistinguishable from the rest of the
parietes; which, as old age sets in, become
thinner than they were previously. This change,
however, is but temporary, for, in extreme old
age, the skull is thicker and more porous than
at any antecedent period of life. This hyper-
trophy is produced by the recession of the
inner from the outer table, and the conversion
of some part of the substance of each into a
thin spongy tissue; the diploe itself sustaining
an analogous alteration, by the enlargement of
its cells, and the thinning of the plates which
form their walls.

Occasional instances occur in which the
skull is of inordinate thickness, and this, appa-
rently, without its being connected with the
age ofthe subject. The late Mr. Joshua Brookes

some sections of a skull, found in a church-
yard in Lancashire, of nearly three quarters of
an inch in thickness; and specimens have been
seen of more than an inch. In some of them
the diploe is perfect, the augmentation being in
the two tables; in others, and indeed in the
majority of specimens, the two tables and _ the
diploe are confounded together in one thick
mass of matter, which is of an ivory hardness. It
is not improbable that we might justly refer this
VOL. I,

745

condition, as well as some other peculiarities of
the cranium, to inflammation of the bone itself,
or of its investing membranes. That exostosis
is the product of a limited periostitis admits of
but little dispute, and it is very likely that those
cases of hyperostosis in which there isa uniform
deposit of bone, only mark the effect of a more
diffused and general inflammation; the more
sO, since we meet with these local and general
deposits, as well on the inner, as on the outer
table of the skull, and for the existence of which
it would otherwise be impossible to account.

When they occur on the inner table, the func-
tions of the brain are usually more or less dis-
turbed, although it would appear that the mental
manifestations are not always implicated. In
the skull of an idiot of advanced age, examined
several years since by the writer of this article,
there was a uniform deposition to the extent of
nearly a quarter ofan inch ; and inarecent autopsy
ofa young girl, he found the entire syncipital
region very irregular in its surface, from being
studded with variously-sized nodules, the bases
of which flowed into and were lost in each other.
This girl was of feeble intellect, and the victim
of epilepsy. In the examination ofa body at
the Hotel Dieu, by Mr. King, that gentleman
discovered on the petrous portion of the tem-
poral bone a tumour which he had not been led
to expect by any indication of suffering which
appeared during life. This tumour had the
volume of a marble or pistol-bullet, was cel-
lular in its structure, and perfectly smooth on
its surface ; a depression exactly corresponding
to it was found on the under surface of the
middle lobe of the brain, but its substance and
membranes had their normal characters.

The cranium is oftentimes found in the oppo-
site state of atrophy, in which the balance be-
tween deposition and absorption seems to have
been disturbed, so much to the prejudice of
the former, that the walls are sometimes not
much thicker than a piece of paper. When-
ever the two textures maintain their usual pro-
portion, this atrophy may be regarded as a
natural abnormal state; but those cases in
which either the inorganic or animal element
preponderates, and a fragility or softening of
the bone is thereby established, must be referred
to some constitutional affection in which the
rest of the osseous system has participated,
and the influence of which it will not fail to
exhibit.

In addition to exostosis and hyperostosis, the
cranium sustains other pathological changes as
the effects of inflammation. '

Previously to the establishment of osteitis,
whether from a common or specific cause,
mercurial or syphilitic, there is found that stasis
of the blood which always precedes inflam-
mation. The sanguineous complexion of the
diploe in eases of erysipelas testifies that this
engorgement may be produced by increased
action in the neighbouring teguments.

It has already been stated that hypertrophy
of the cranium may be regarded as a termina-
tion of osteitis. When inflammation is limited
in its action and of long duration, it is probable
that the ossific element is poured into the cells

ZC

746

of the diplde so as to effect their obliteration ;
but when it is of a more vivid character, the
opposite effect of softening (the precursor of
ulceration) takes place, and both the outer and
inner tables are rendered friable. This fre-
quently occurs to a great extent in the mastoidal
cells, especially in children; and as, in them,
the posterior portion of the meatus auditorius
internus teen an unclosed fissure, the dis-
charge which is consequent on the destruction
of the cells is allowed an exit, before the mem-
brana tympani is destroyed ; although that, as
well as the whole of the internal ear, is fre-
quently involved in the ravages of the disease—
then, however, having passed into another ter-
mination of osteitis, viz. ulceration.

Adhesion can take place only where the cra-
nium has experienced a lesion froma mechani-
cal cause; and it is altogether prevented if the
solution of continuity be great. The edges ofa
wound, produced by a cutting instrument
penetrating more or less perpendicularly to the
surface of the bone, do not approximate; but
they are united by an interposing callus as in
the case of a common fracture, and the line
formed by it is always visible in the same
way as the cicatrix which persists after the ad-
hesion of soft parts.) When a piece of the
outer plate is elevated by a cutting instrument
passing very obliquely to the surface of the bone,
and the scalp is not detached, it will, on being
immediately re-applied, unite with the surface
from which it has been raised; and, if it be
altogether removed, the reparation will be
effected in the same way as in other parts, viz.
by the granulation and cicatrization of the cut
surface.

When there is loss of substance of the entire
thickness of the bone, whether that loss be pro-
duced by mechanical or pathological causes,
granulations spring up from the dura mater ;
the edge of the opening becomes very thin;

the surface cicatrizes and produces the appear- ~

ance of a dense fibrous membrane, the circum-
ference of which is attached to the margin of the
hole and the adjacent pericranium.

Caries, which is analogous to ulceration of
the soft parts, and is, in fact, an ulcerative ab-
sorption of bone, attacks the cranium in com-
mon with the rest of the osseous system ; but it
always first appears on one of the two tables,
and not on the diploe, although ultimately the
entire thickness is, in some cases, involved.
Indeed, when it commences on the inner table,
it is only by the extension of the ulcerative pro-
cess through the substance of the bone, that
the suppurative collection can be emancipated.

In this affection the pericranium is sometimes
enormously thickened and almost inseparably
attached to the rough biscuit-like surface of the
bone beneath. In other cases, especially in
those in which the ulcerative process has been
provoked by mercury, it is in irregular patches;
the pericranium is unattached and the denuded
surface is of a dark colour.

Necrosis, or mortification of the bone, is of
frequent occurrence ; but not in the way usually
implied by that term. Whether it be the sub-
stance of the bone, or merely its outer lamina

REGIONS AND MUSCLES OF THE CRANIUM.

Jrontal region.

which is deprived of its vitality, the reparation
is not by a fresh deposition of bone, nor is
it coeval with the separation of the necrosed.
part, as in the long bones; but it is a subse-
quent action (such as has been already pointed
out) which is established to supply the loss.
Considerable portions of the frontal and parietal
bones may thus be thrown off and the deficiency
provided for by the granulations of either the
subjacent diploe or the dura mater.

Medullary sarcoma sometimes manifests
itself in the cranium. It appears to commence
in the diploe by a deposition of tuberculous
matter, which softens, and which in that state
may be mistaken for pus; the inorganic ele-
ment is withdrawn; the accumulation con-
tinues and advances towards both tables, which
in turn submit to the same change of structure;
and, ultimately, a tumour is formed, the capsule
of which is constituted, on the one side by the
pericranium, and, on the other, by the dura
mater. In this tumour the knife detects spicule
of bone interspersed throughout its substance,
and the edge of the opening which is left in the
skull after maceration, is studded with irregular
projecting points.

7

For the Bibliography, see OSSEOUS SYSTEM.
(J. Malyn.)

CRANIUM, REGIONS AND MUSCLES
OF THE, (Surgical Anatomy.)—If a line be
drawn on the skull from the external angular
process of the frontal bone, backwards along
the rough line on that and the parietal bone,
which indicates the attachment of the temporal
fascia, be continued downwards and backwards
parallel and a little external to the occipito-
mastoid suture, and then be carried forwards
along the inferior surface of the occipital bone to
end just behind the foramen jugale, and a little
internal to the stylo-mastoid foramen,—this
line, with another similar one on the other side,
will include an oblong region which has very
natural limits both before and behind. Ante-
tiorly this region is limited on each side by the
anterior margins of the roof of the orbit, in
the centre by the line of articulation of the
frontal bone with the nasal and superior maxil-
lary, posteriorly by the superior curved line of
the occipital bone, and on each side by the
mastoid process. To this oblong region may
be appropriately given the designation occipito-

The line which thus limits laterally the region
just named circumscribes another region which
occupies nearly the whole lateral surface of the —
cranium, and which is called the temporo-
parietal region. This region passes into the
base of the cranium, and may be limited below
and within by a line from the styloid process
external to the glenoid cavity, as far as th
spheno-maxillary fissure.* a

* Blandin makes five cranial regions
frontal, temporal, auricular, mastoid, and the regic
of the base of the cranium: the last is quite ou
of the reach of the surgeon, and therefore
excluded from consideration in the present arti
Velpeau has three regions,—the frontal, tempo

Lee
OCCU
&

rl oO

REGIONS AND MUSCLES OF THE CRANIUM.

¥. Occipito-frontal region.—The anterior and
posterior boundaries of this region are suffi-
ciently obvious on the integuments, the eye-
brows forming the anterior, the posterior being
constituted by a line extending as far as the
mastoid process on each side of the occipital
protuberance corresponding to the insertion of
the superficial muscles of the back of the neck,

- which protuberance can be felt through the

integuments. The lateral limits, however, are
not so distinct; in the living subject, however,
when the temporal muscle is rendered tense, a
distinct line of demarcation is felt along the
upper margin of this muscle, extending down-
wards and backwards nearly as far as the mas-

- toid process.

e proceed to examine the several structures
which are presented to the anatomist as he
pursues the dissection of this region.

1. Integument.—It is in this region that we
can best examine the general characters of the
integument of the cranium, commonly known
under the name of scalp (Fr. cuir chevelu).
The greatest part of it is remarkable for the
more or less luxuriant growth of hair from it,*
the nature of which, it is hardly necessary to
observe, differs materially in the male and in
the female. In the natural state about two-
thirds or three-fourths of the scalp are covered
with hair, the anterior third or fourth,—namely,
the skin of the forehead,—being uncovered.
In front the hairs terminate abruptly on the
frontal region; behind they terminate less ab-
ruptly, and descend in general to a variable
distance on the posterior part of the neck,
becoming finer and more downlike as they
descend. The natural direction of the hairs
is at right angles with that portion of the scalp
from which they grow; consequently the dif-
ference of direction of the hairs depends upon
the differences in the aspects of those regions.
This is most obvious in that part of the head
which is called the crown, which in most per-
sons inclines downwards and backwards to a
greater or less extent. Such, however, is the

ietal, and occipito-mastoid. The advantages to

derived from the subdivision of the body into
so many small regions as is adopted by the French
anatomists, are byno means obvious. I decidedly
prefer a subdivision which is indicated by certain
naturally prominent points or landmarks, which
will, 1 think, in general be found to map out
regions not too limited nor too numerous, nor yet
too comprehensive.

* We cannot resist the temptation of transcribing
the following passage from Gerdy, which is not
devoid of some national characteristics. <* La
surface supérieure de la téte est arrondie et ovoide.
Elle est couverte par les cheveux qui en cachent
les formes, lui donnent, par la soupplesse et le
contraste de leur couleur, une sorte de beauté dif-
ficile 4 exprimer, et fournissent au gout delicat des
femmes l’ornement le plus gracieux et le plus se-
duisant par les masses legéres, les guirlandes flex-

- ueuses, les boucles arrondies qu’elles en composent,
et par les mille arrangemens que suggere a leur
imagination amour on V’art de plaire. Mais la
téte, se depouillant avec l’age, de la chevelure
qui l’embellisait, ne presente plus dans la vieillesse
qu’une surface nue et luisante, ou l’on entrevoit
— la trace des sutures frontales et parie-
tales.

747

influence of art in the arrangement of the hair,
that it is difficult to meet with “a head of
hair’”—to borrow the phrase from the hair-
dresser,—where the growth is perfectly na-
tural.

There is an obvious difference in the nature
of that portion of the scalp from which hairs
grow, and that which is naturally bald: the
former is much thicker and denser, owing, no
doubt, to a larger developement of the fibres
of the corion, and to the great magnitude of
the hairs which pierce it. It is at the posterior
part of the occipito-frontal region that the hairs
are strongest, and that portion of the scalp
very rarely becomes bald.

2. Subcutaneous tissue.—Subjacent to the
integument is a dense and lamellated_ cellular
tissue, with little fat, and such as does exist.
deposited in small pellets, much more nume-
rous in the posterior part of the region. This
cellular membrane is very intimately connected
with those parts of the scalp especially from
which hairs grow ; it is much more loose and
less adipose in the frontal region; it also ad-
heres pretty closely to the subjacent aponeurotic
expansion of the occipito-frontalis muscle.
The bulbs of the hairs are lodged in it. The
firm adhesion of this cellular membrane on
the one hand to the skin, and on the other to
the subjacent aponeurosis, is sufficient to ac-
count for the great pain and danger which at-
tend punctured wounds of the scalp, in conse-
quence of the non-extensibility of the membrane
and the tension which a very slight degree of
swelling consequently gives rise to.

3. Muscles.—IV the scalp and subcutaneous
tissue be divided by a transverse incision over
the vertex, and the flaps carefully dissected off,
—one as far as the eyebrows, the other to the
superior curved line of the occipital bone, the
occipito-frontalis muscle is brought into view.

_Anteriorly and inferiorly we find the few fibres

of the orbicularis palpebrarum muscle overlap-
ping the occipito-frontalis just above the mar-
gin of the orbit.

Occipito-frontalis (epicranius, Albin.: de-
scribed by some anatomists as two distinct
muscles, the frontal and occipital).

This is an expanded digastric muscle occu-
pying the whole of this region. The two bellies
of which the muscle is compoSed are united in
the centre by a broad aponeurotic expansion.
The anterior belly corresponds to a great part of
the frontal bone, and the posterior to a part of
the occipital. Very frequently the fibres are
weak and pale, so that the dissector finds it
difficult to trace out the extent and attachments
of the muscle; and, moreover, even in its most
developed state it is a thin muscle, so that great
care is required for the accurate dissection of it.

The anterior belly of this muscle, or that
which is by some called the frontal, consists
distinctly of two lateral portions united by a
narrow triangular slip of aponeurosis. Each
portion is connected inferiorly to the integu-
ment of the eyebrow through the intervention
of cellular membrane, and slightly overlapped
by the superior fibres of the orbicular muscle of
the eyelids, and commingled with Pa of. the

3.C

748

fibres of the last named muscle, as well as of
the corrugator supercilii. The aponeurotic
slip before alluded to, situated in the middle
line, forms the internal boundary of each la-
teral portion. On the outside the fibres gra-
dually shorten and extend a very short distance
into the temporal region, over the temporal
fascia. Each portion presents a convex margin
above, which is inserted into the thin tendinous
aponeurosis, which extends over the middle
portion of the occipito-frontal region, correspond-
ing to the posterior margin of the frontal bone,
the fronto-parietal suture, internal portions of
the parietal bones, the sagittal and lambdoidal
sutures and part of the occipital bones, but se-
parated from them by the pericranium and by
some fine cellular tissue which connected the
aponeurosis to the last-named membrane. This
aponeurosis is called the cranial or epicranial
aponeurosis : in some instances its fibrous cha-
racter is very distinct in all its extent ; but very
frequently it is most manifest in its posterior
third or half, the anterior part being little more
than condensed cellular membrane, excepting
near to the fleshy fibres of the frontal portion of
the muscles, where the aponeurotic structure
again becomes manifest. On the sides this
aponeurosis gradually degenerates into cellular
membrane without leaving any defined margin.
The aponeurosis in its whole extent adheres
closely to the superjacent subcutaneous cellular
tissue and to the subjacent pericranium through
the intervention of a fine cellular membrane
already referred to. Proceeding from before
backwards, we find that this aponeurosis ends
in affording insertion. to the fibres which form
the posterior belly of the muscle.

This portion of the muscle, also called the
occipital muscle, consists likewise of two lateral
portions which are attached inferiorly to the ex-
ternal part of the superior curved line of the
occipital bone, and to the mastoid portion of
the temporal. The fibres are parallel and
nearly vertical, inclining a little inwards, and
are inserted, as already described, into the pos-
terior margin of the epicranial aponeurosis.
The attachment of the muscle to the occipital
bone is immediately above that of the sterno-
mastoid and splenins muscles. On the sides
the fibres gradually disappear over the mastoid
portion of the temporal bone, and the fleshy
belly of the muscle lies immediately over the
pericranium, some cellular membrane only in-
tervening ; its adhesion to the skin, however, is
less intimate than that of the frontal portion.

This muscle is evidently destined to act upon
the integuments of the cranium: its influence
is most apparent upon the skin of the forehead
and eyebrows; it distinctly raises the latter,
and throws the former into transverse wrinkles.
Under its influence the whole scalp may be
made to move backwards and forwards, but the
occipital portion of the muscle cannot create, as
the frontal does, wrinkles in its corresponding
integument, owing to the less firm adhesion of
the muscle to it.

Subjacent to the anterior portion of the occi-
pito-frontalis is the corrugator supercilit muscle.
It lies on the inner half or third of the orbital

REGIONS AND MUSCLES OF THE CRANIUM.

margin of the frontal bone. By its inner extre-
mity it is attached to the internal angular pro-
cess of the frontal bone; the fibres thence
outwards, inclining a little up s, and are
inserted into the integument of the eyebrow,
being mixed with the orbicularis and occipito-
frontalis muscle. This muscle evidently can
depress the eyebrow, and acting in conjunction
with its fellow, throw the integuments ~into
vertical wrinkles, approximating the eyebrows,
and occasioning the act of frowning. This
muscle lies on the supra-orbital nerve and
vessels.

4. Nerves.—The anterior part of the occi-
pito-frontal region is freely supplied with nerves
from those branches of the ophthalmic portion
of the fifth which originate within the orbit. Of
these the supra-orbital is the largest: imme-
diately after its emergence from the supra-or-
bital foramen this nerve divides into a series of
branches which pass up on the forehead, some
adhering to the pericranium, others distributed
to the muscle, and others becoming subcu-
taneous. Here, too, we find ramifications of
the supra-trochleator or internal frontal nerve,
chiefly distributed in the internal portion of the
muscle. At the external part of this frontal
region we find some filaments of the portio
dura. In the posterior or occipital region the
principal nerves are derived from the cervical
plexus; the auricular and mastoid branches of
this plexus distribute their filaments here; and
we also find ramifications from the posterior
branch of the first cervical nerve, aecompany-
ing the subdivisions of the occipital artery.

5. Arteries-—In front we have ramifications
of the supra-orbital and superficial temporal
freely anastomosing with each other; and
deeper-seated, a few branches of the deep
temporal, distributed to the pericranium. In
the occipital region we have the occipital,
often of considerable size, and the posterior
auricular also sends some of its ramifications
to anastomose with the occipital branches.
Both in front and behind, the arteries of op
site sides inosculate with each other on the
middle line.

6. Veins.—Small veins accompany most of
the arteries; but the most remarkable vein is
one which is situated in the frontal region
nearly on the middle line; it is the frontal
vein, or vena preparata, sometimes replaced
by two or three. Velpeau advocates the re-
vival of the ancient practice of bleeding from
this vein in head affections. It carries the
blood, as he observes, from all the anterior part
of the head to the root of the nose, whence he
argues that venesection practised on this vessel —
would empty the whole of the scalp. How —
often in practice do we see manifest advantag
from cupping the temples or some region of
the scalp, when little or no benefit had bee
derived from other modes of practising the
detraction of blood !

7. Lymphatics—The lymphatics are very
few, and pass into the parotid ganglions, or
those behind the ear or in the superior part 0}
the neck. ’ a

8. Pericranium.—This fibrous tissue,

/ a. i a Bi

o> A
ee, ee ee

7
A

and the fascia.

REGIONS AND MUSCLES OF THE CRANIUM. 749

sessing the same properties as the periosteum
in other parts of the body, is, in a practical
point of view, not the least interesting structure
which is to be found in this region. It is
largely supplied with blood, more especially
in early life. We have already noticed its
adhesion to the superjacent aponeurosis ; it
adheres to the bone by cellular membrane, and
is easily raised from it by dissection in all
points except where there are sutures. This
membrane is not unfrequently the seat of peri-
ostitis and of nodes.

II. Temporo-parietal region.—The lateral
boundary of the occipito-frontal region consti-
tutes the superior limit of this region, and a
line drawn from the external angular process of
the os frontis backwards and a little down-
wards along the zygoma to the mastoid process
of the temporal bone, limits it inferiorly.

The integument and subcutaneous cellular
membrane of this region differ but little from
the same structures in the occipito-frontal re-
gion. The former is finer and not so thick as
in the middle and posterior parts of the last-
named region. The hairs are oblique, some
directed forwards, others backwards towards
the occiput, and others downwards overlap-
ping the ears. Here the hairs first begin to
Brow grey, whence the denomination tempora

as been applied to these regions, grey hairs
marking the inroads of time. The skin of this

_Tegion, however, is naturally bald for a consi-

derable portion in front of the ear, and for the
distance of about an inch immediately behind
and above it. 4

The subcutaneous cellular tissue is very
loose in front of the ear, but behind it in the
vicinity of the mastoid process, it is more
dense, and hence the scalp is much less move-
able over that process, and immediately be-
hind the ear. e epicranial aponeurosis is
confounded with this subcutaneous tissue in
the superior part of this region.

Temporal fascia.—Subjacent to the cellular
expansion is a fibrous membrane of consider-
able strength, which stretches from the zygoma
below to the curved line above and behind
which limits the temporal fossa on the frontal,
parietal, and temporal bones. It is very thick
and strong, composed of white interlacing fi-
bres, firmly attached to the points of bone
referred to, and giving attachment by the

ter part of its deep surface to the fibres of
he temporal muscle. In front and below,
however, for a short space, some adipose cel-
lular membrane intervenes between the muscle
Along the margin of the zy-
goma, especially in front, the fascia is divisible
into two lamine, which pass down, one in-
ternal, the other external to the bone, and
become incorporated with periosteum: by their
separation above the zygoma they leave a tri-
angular space which is in general filled with
cellular tissue more or less adipose.

Muscles—Some fibres of the occipito-
frontalis extend more or less into this region,
according to the state of developement of the
muscle. Tere too we find the three auricular

_ muscles immediately subjacent to the subcu-

taneous cellular tissue. (See Ear.) Under the
temporal fascia and adhering to its deep surface
is the fleshy portion of the temporal muscle,
attached to almost the whole of the fossa.
Behind, the mastoid process is enveloped by
the tendinous insertion of the sterno-mastoid
muscle. .

Nerves.—The nerves of this region are very
numerous. Thesubcutaneous ones are derived
from the portio dura and the superficial tem-
poral or auricular of the fifth, and posteriorly
from the mastoid and digastric branches of the
pene dura, as well as some from the ascending

ranches of the cervical plexus. The deep-
seated nerves in the temporal fossa are the deep
temporals from the inferior maxillary, and the
temporal filament of the orbitar branch of the
superior maxillary.

Arteries—The superficial arteries are nu-
merous and important. They are derived from
the trunk of the superficial temporal, which
enters this region by passing over the zygoma
in front of the tragus, crossed over by the
anterior auris muscle. After it has passed the
zygoma it inclines forwards, and is a little more
distant from the ear than when on the zygoma.
In all this course it may be felt distinctly,
although it is pretty firmly bound down by the
subcutaneous tissue and epicranial aponeurosis,
which are here conjoined. A little more than an
inch above the zygoma it divides, and we trace
its anterior branch forwards towards the frontal
region, which it enters and anastomoses with
the supra-orbital. The posterior branch passes
upwards and backwards, winding over the ear,
and anastomoses with ramifications from the
occipital artery. It is in one or other of these
branches that arteriotomy is generally performed,
in preference to opening the trunk of the artery.
The middle branch of the temporal artery pierces
the fascia, and enters the substance of the tem-
poral muscle, anastomosing with the deep
temporals. The posterior part of this region 1s
supplied from branches of the occipital and
posterior auris.

Veins.—Veins accompany almost all the
arteries; there are none worthy of any special
notice.

Lymphatics.—These vessels likewise accom-
pany the arteries, and enter the ganglions in
the neighbourhood of the ear, and those of the
neck,

Pericranium.—The pericranium does not
differ from that of the occipito-frontal region,
except perhaps in firmer adhesion to the squa-
mous portion of the temporal bone. It
affords insertion to the fibres of the temporal
muscle. This region presents more surgical
interest than the former one; it is more fre-
quently the seat of operation (arteriotomy, and
in its posterior part, that of opening the mastoid
cells); and in consequence of the number of its
arteries and nerves, and the great strength of
the temporal fascia, wounds in this region are
of a more dangerous kind. Fractures here are
also liable to be complicated with a wound of
the middle meningeal artery, part of the course

of which corresponds to this region.
(R. B. Todd.)

750

CRUSTACEA. Eng. Crustaceans; Germ.
Krustenthiere; Fr. Crustacés —This is the
name given to a class of articulated animals,
the type of which we have in the common crab
and lobster, and which is essentially distin-
guished by the conformation of the organs of
circulation, of respiration, and of locomotion.

The body of these animals is articulated ;
that is to say, it is divided into rings, for the
most part very distinct and partially move-
able; their integuments are of considerable
consistency, being either horny or calcareous,
and form a kind of external skeleton; their
extremities are also articulated, arranged in a
double series, and constitute antenne, jaws,
limbs, (ambulatory, natatory, or prehensile, the
most common number of which is five or seven
pairs,) and other appendages; their nervous
system is ganglionic, situated partly in front of
the alimentary canal, and partly behind and
below the intestine; their blood is colourless,
and put into motion by an aortie and dorsal
heart; their respiration is almost invariably
aquatic, and is accomplished by means of
branchiz, or the skin only; to conclude, the
sexes are distinct, and the organs of genera-
tion double.

Great and striking analogies occur between
the Crustacea, the Insecta, and the Arachnida;
so that it was long the custom to associate the
whole of the animals now comprised in these
three classes, under the single name of In-
secta, or Insects. Brisson and Lefranc
de Berkhey proposed, it is true, to separate
the Crustacea, but the classifications of these
writers not being based upon organic charac-
ters of sufficient consequence, did not receive
the general assent of naturalists, and it is only
since the beginning of the present century that
the necessity of separating the annulosa into
certain distinct classes has been universally
acknowledged. This result was mainly due
to the anatomical inquiries of Cuvier, and
this great naturalist was even the first who
established a class among the invertebrate
series of animals for the reception of those
having bloodvessels, a ganglionic spinal cord,
and articulated extremities, characters which,
at the present time, still suffice to distinguish
the Crustacea from the greater number of other
animals.

It is more especially in the general confor-
mation of the body, in the structure of the

CRUSTACEA.

extremities, and in the organization of the ner=
vous system, that the Crustacea resemble the
Insects and Arachnidans. The apparatus o
vegetative life in these different animals pre
sents numerous and important differences. ‘Thus
Insects, instead of breathing by means of bran-
chie, and possessing a vascular system like the
Crustacea, breathe by means of trachee, and
have no bloodvessels; and Arachnidans, which,
like the Crustacea, have a heart more or less
perfect, and distinct vessels for the circulation
of their blood, have an aerial respiration ef-—
fected either by the medium of trachee or of
pulmonary sacs.

The whole of the Crustacea are evidently
formed after one and the same general type;
still, numerous and extensive varieties of struc-
ture are observed among these animals; and
when compared one with another, their orga-
nization is found to become more and more
complicated in proportion as we rise in the series
comprised by the group; it is farther found
that the lower links of this kind of chain re-
present, to a certain extent, the different phases
through which the more perfect Crustaceans
pass during the period of their embryonic ex-
istence.

This diversity of organization affords the
grounds by which naturalists are guided in
their distribution of the Crustaceans into orders
and families.

The natural arrangements of these animals
that have been followed, are consequently ob-
served to vary with the extent of knowledge of
their structure possessed. It were tedious to
enter upon the consideration of the different sys-
tems which have been successively proposed for
their classification; in order to aid the mind in
the comprehension of the anatomical details
into which we shall have to enter in the course
of this article, it will be enough for us to pre-
sent at once those divisions which appear to
indicate most truly the differences and resem-
blances subsisting between the various mem-
bers of the class;* and to do this in the most
compendious manner, and to exhibit the clas-
sification which thence ensues, we shall present
them to the reader in the shape of a synoptical
table.

* See Histoire Naturelle des Crustacés, par M.
Milne Edwards, vol. i. p. 231.

751

CRUSTACEA.

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752

§ 1. Of the skin or tegumentary skeleton, and
of the organs of locomotion.

In the definition which has been given of
the Crustacea, one of the most important cha-
racters was derived from the nature and dispo-
sition of their tegumentary system. And it is
from this point that we shall start in laying
before our readers a detailed account of the
peculiarities of organization presented by this
class of animals. By pursuing this course all
the subsequent parts of the present article will
appear clearer, the disposition of the internal
organs, their forms, their mutual relations, &c.
being in a great number of instances readily
explicable by the various modes of confor-
Mation of the modified skin, which in this
class performs the important office of the in-
ternal skeleton among the Vertebrata.

In some Crustacea the skin always con-
tinues soft, but in the greater number it
presents a great degree of solidity, and forms
a solid casing, within which are included
the whole of the soft parts. This difference
in the condition of the tegumentary envelope
is generally found to coincide with the pre-
sence or absence of particular organs for the
purposes of respiration; and in fact it is easy
to understand that in those species in which
this important function is performed by the
surface of the body at large, the integument
required to be membranous, whilst in those in
which the covering is of stony hardness, a con-
dition which renders it incompetent to expose
the blood to the contact of the atmospheric
air dissolved in water, respiration can only be
performed by the medium of organs especially
contrived and set apart for the purpose.

When the tegumentary envelope of the Crus-
tacea is studied among the more elevated indi-
viduals of the class, it is found to possess a
somewhat complex structure; parts may be
distinguished in it comparable to those which
are known to constitute the integument of the
Vertebrata. Among the Brachyura, for in-
stance, the integument consists of a corium
and an epidermis with a pigmentary matter of
a peculiar nature destined to communicate to
the latter membrane the various colours with
which it is ornamented.

The corium or dermis, as among the Verte-
brata, isa thick, spongy, and very vascular mem-
brane; on its inner surface it is intimately con-
nected with a kind of serous membrane, which
lines the parietes of the cavities in the Crus-
tacea in the same manner as the serous mem-
branes line the internal cavities among the Ver-
tebrata ; these two membranes, divided in the
latter order by the interposition of muscular
and bony layers, which cover and protect the
great cavities, become closely united when
these layers disappear, as they do in the Crus-
tacea in consequence of the important changes
that take place in the conformation of the ap-
paratus of locomotion.

The corium, again, among the Crustacea, is
completely covered on its outer surface by a
membranous envelope unfurnished with blood-
vessels, and which must be held in all respects
as analogous to the epidermis of the higher

CRUSTACEA.

ee

animals. It is never found in the propeey
membranous state, save at the time of the Crus- ;
tacea casting their shell; at this period it is
interposed between the corium and the solid
covering, ready to be cast off, and has the
appearance of a pretty dense and consistent
membrane, in spite of its thinness. It forms,
as among animals higher in the scale, a kind of
inorganic lamina, applied to the surface of the
corium, from which it is an exudation. After d
the fall of the old shell, it becomes thicker and ‘
very considerably firmer, owing to the deposi-
tion or penetration of calcareous molecules
within its substance, as well as by the addition
of new layers to its inner surface. The degree
of hardness finally acquired, however, and the
amount of calcareous matter deposited within
it, vary considerably; in many members of the
class it remains semi-corneous, in a condition
very similar to that of the integuments of in- .
sects, with which, moreover, it corresponds
very closely in point of chemical composition ;

in the higher Crustaceans, again, its composi-

tion is very different: thus, whilst chitine in
combination with albumen is the principal
element in the tegumentary skeleton of some
species, this substance scarcely occurs in the
proportion of one or two-tenths in the carapace

of the Decapods, which, on the contrary, con-
tains sixty and even eighty per cent. of phos-
phate and carbonate of lime, the latter sub-
Stance particularly occurring in considerably
larger proportions than the former.*

With regard to the pigmentum, it is less a
membrane or reticulation than an amorphous
matter diffused through the outermost layer of
the superficial membrane, being secreted like
this by the corium. Alcohol, ether, the acids,
and water at 212° Fahr. change it to a red in
the greater number of species; but there are
some species in which it may be exposed to the
action of these different agents without under-
going any perceptible change. 4

The epidermic layer hardened in different
degrees is the part which mainly constitutes
the tegumentary skeleton of the Crustacea. In
its nature it is obviously altogether different
from that of the internal skeleton of the Verte-
brata; still its functions are the same, and this
physiological resemblance has led naturalists to
speak of these two pieces of organic mecha-
nism, so dissimilar in their anatomical rela-
tions, under the common name of skeleton.

The tegumentary skeleton of the Crustacea
consists, like the bony skeleton of the Verte-
brata, of a great number of distinct pieces,
connected together by means of portions of the
epidermic envelope which have not become
hardened, in the same way as among the
higher animals certain bones are connected by —
cartilages, the ossification of which is only —
accomplished in extreme old age. On the ©
varieties which these pieces present in their —

a

—~

* Chevreul and Geoffroy, Journal Complémen- —
taire du Diction. des Sciences Médicales, Avril
1820. Milne Edwards, Hist. Nat. des Crustacés, —
t. i. p. 10. a

174.

+ Lassaigne, Journal d, Pharmacie, t. vi. p.

wi
Ay

CRUSTACEA.

number, their form, their relations, &c. depend
the differences that occur in the conformation
of the solid frame-work, the anatomical study
of which is now about to engage our atten-
tion. —

The most prominent feature in the external
skeleton of the Crustacea is common to the
whole grand division of articulated animals, and
consists in the division of this envelope into a
series of segments or rings, connected in suc-
cession one with another, and supporting tu-
bular appendages, also divided into segments,
and arranged endwise. This peculiar structure
is met with among the whole of the Crustacea;
but when the frame-work of these animals is
examined more narrowly, variations are disco-
vered so extensive and so numerous, that the
mind is almost led to regard it as consisting of
elements essentially different. Yet this is not
so; and in pursuing the study, aided by the
means of investigation developed in the pro-
gress of the philosophy of the natural sciences,
very opposite results are elicited,—results which
are replete with interest and instruction in
regard to the mysteries of nature in her creative
energies.

Now these methods of investigation may be
reduced to two:—the first, which studies crea-
tures at their full growth, after having ar-
ranged them according to the natural order
which follows from the investigation of their
organization : the second, which studies each
creature, but the more perfect in preference, in
the series of successive evolutions which
constitute the different phases of the em-
bryonic state and of extra-uterine life; for it
is a demonstrated fact that these two series,
so distinct, so widely separated in appearance,
are in reality connected by links so inti-
mate, that the one is, in certain respects, the
permanent reproduction of the other, which is
the continual repetition of the first in one and
the same individual.

By studying in this relative or comparative
manner the skeleton of the Crustacea, we suc-
ceed in reducing to common principles the
mode of conformation, apparently so various,
of this apparatus, in the different groups formed
by these animals. A remarkable tendency to
uniformity of composition is every where re-
cognizable, and all the varieties are explicable
in a general way by the laws in conformity with
say the development of these animals takes

ace.

5 During the period of embryonic life the body
is seen becoming divided into rings more and
more numerous, and more and more unlike
one another. The same tendency to diversity
in the organization is also found in the types of
which the series of Crustaceans consists; and in
both instances the differences are readily seen to
depend on various modifications undergone by
parts originally similar. It is farther referable
to one of the most general laws of organiza-
tion, viz. the tendency which nature shows to
perfect functions by subdividing the work to be
done, and throwing it upon a greater number of
special organs. And we observe, in fact, among
the most inferior animals that the different seg-

753

ments into which the body is divided are so
completely repetitions of one another, that
they all act precisely in the same manner;
they severally include the elements necessary
to the display of the vitality distinctive of the
entire system to which they belong, so that
they may be dissevered without any function
whatsoever being therefore the less completely
performed in either of the detached portions.
Many Annelidans present instances of this
uniformity of composition. As we rise, how-
ever, in the scale of beings, the different seg-
ments of the body are found to become more
and more unlike, both as regards their func-
tions and their conformation.

This law is also visibly manifested among the
Crustaceans, whether they be studied at the
various epochs of their embryonic state or
compared together, examples being selected
from the different groups of which this portion
of the animal series consists. In either case a
well-marked tendency to subdivision of the
physiological operations is conspicuous; and
im proportion as the divers acts, the aggregate
of which constitutes the life of the individual,
become attached to a particular system or
place, the parts to which different functions
are apportioned, acquire forms more dissimilar
and more appropriate to their peculiar uses.
When we come to treat of the evolution of the
embryo of the Crustacea, we shall have occa-
sion to revert to this subject, but it is neces-
sary so far to hint at it in this place, inasmuch
as the conclusions which have been mentioned
will often supply us with means of explaining
those difficulties that are encountered when we
seek to render comparative the study of the
different constituent parts of the external ske-
leton of the articulated series of animals.

The frame-work or solid parts of the Crus-
tacea consist, as we have said, of a series of
rings.

The number of these rings may vary, but
this happens to a much less extent than on a
superficial view we might be led to conclude.
By calling in to our aid the principles of ob-
servation and of comparison pointed out above,
we have found that in every member of this
class of animals the normal number of seg-
ments of the body is twenty-one. But
avery few instances of a larger number oc-
curring are known, and it seldom happens
that the number falls short of that which has
been indicated. Occasionally, it is true, one
or more rings prove abortive, and are never
developed ; but in general their apparent ab-
sence depends entirely on their intimate union
one with another, and other obvious indica-
tions of their existence may be discovered.
By-and-by we shall find that in the embryo
these segments are formed in succession from
before backwards, so that, when their evolution
is checked, the later rather than the earlier
rings are those that are wanting; and in fact it
is generally easy to see in those specimens of
full-grown crustaceous animals whose bodies
present fewer than twenty segments, that the
anomaly depends on the absence of a certain
number of the most posterior rings of the body.

754

‘The Leemodipods, the Entomostraca, and the
Haustellate Crustacea present us with instances
of this condition, which calls to mind one of
the stages through which the einbryo of the
higher species, whose development is the most
complete, is known to pass.

Each segment of the body, when it attains its
normal condition, consists of two distinct ele-
ments : the central or annular portion, and cer-
tain appendices which it supports.

The central or annular portion of the seg-
ments of the tegumentary skeleton presents, in
its most simple state, the appearance of a com-
plete ring, but instead of a single piece it is
requisite to count in its composition no fewer
than eight, as has been demonstrated by the
inquiries of M. Audouin on the structure of the
thorax of insects,* inquiries the results of which
are immediately and almost wholly applicable
to the Crustacea so nearly allied to the insects
in their organization. Each ring is divided
first into two arcs, the one superior or dorsal,
the other inferior or ventral, and each arc may
present as many as four elementary pieces,
‘Two of these pieces by being united in the me-

Theoretical figure illustrating the composition of the
tegumentary skeleton of Crustacea.
D, Dorsal arc; t,t, tergal pieces; e, e, epimeral
pieces; V, ventral arc; s,s, sternal and episternal
pieces; P, insertion of the extremities.

dian line constitute the fergum (fig. 378, D) ;
the superior are is completed on either side by
two other pieces, known under the name of flancs
or epimeral pieces (fig. 378, e). The inferior
are presents in its composition an exact counter-
part of the superior. Two of the four pieces
into which it may be resolved constitute the
sternum, situated in the median line, and are
flanked by the two episternums. The two ares
thus composed, instead of cohering by their
edges, leave a space for the insertion of the
lateral appendages or extremities which corre-

Anterior partion of the body of an Amphipoda.
t, tergum of the fourth poet, ring ; e€, epimera
of the same ring.

spond with them. It is true, indeed, that we
have no instance of any single ring which exhi-
bits the whole of these pieces distinct from one
another ; in general several are anchylosed so

* Annales des Sc. Nat. tom. i.

CRUSTACEA.

as to a but one; | ; the comparative =
study of e apparatus in the different members ’
of the class at large, leaves no doubt of their

existence severally. ;
wes

Thorax of an Atelecyclus seen below.

a, sternal pieces of the second thoracic ring; 6,
episternal piece of the corresponding ring ; ¢, epi-
meral pieces; d, apodemata, which run from the
sternum to the epimera, and separate the inser-
tions of the extremities; e, antipenultimate ring
of the thorax presenting the orifices of the female
reproductive organs.

It frequently happens that the tegumentary
membrane is folded so as to penetrate more or
less deeply the interior of the ring among the
different organs which fill the cavity. These
folds, which may become solid lamine by
being impregnated with calcareous salts, have
received the name of apodemata, and always
proceed from the lines of conjunction of the
different pieces, or of the different rings with
one another. We shall have occasion to revert
to this part of our subject very shortly.

Fig. 381.

Qe

Thorax of the Maja Squinado, shewing the apode-
mata which form septa between the sternum and
the epimeral pieces of the thoracic rings.

;
The structure of the ring once investigated
;

in the manner we have done, let us now pro-
ceed to inquire in what manner the different
rings by the modifications they undergo, and
by the divers modes of union they present, give
rise to the variety of forms we observe among
the Crustaceans.

By general consent and usage, three regions
are recognized in the bodies of these animals,—
a head, a thorax, and an abdomen ; and from this
custom we shall not depart, although we must
avow that these denominations are only derived
from very clumsy views, and are calculated to
convey false impressions in regard to the nature —
and composition of the parts so named, by —
leading the mind to liken them to the grand —
divisions entitled head, thorax, and a nen
in the Vertebrata. Nevertheless, with the ex-
ception of the objectionable names, the division
of the body into three regions is not less a fact
as regards the organization of the Crustaceans;
and the one-and-twenty rings of which, as we
have said, their body consists in the type to
which every member of the class may be re-
ferred, are generally found divided into three

CRUSTACEA.

Talitra Saltator magnified.
a, head; 6, thorax composed of seven distinct
rings ; c, abdomen composed also of seven dis-
tinct rings.

equal series of seven, each of which may be
held as corresponding with one of the three
regions. This law of composition is observed
to obtain not only among the more simple
species, where the rings generally resem-
ble each other most closely, but its influence
may be remarked among the most complicated
also, and amidst exceptions and contradictions
in appearance the most obvious. The head or
cephalic region includes the principal organs
of sense as among the Vertebrata, the com-
mencement of the apparatus subservient to
digestion, and the appendages destined to seize
and masticate the food. The thorax, strictly
speaking, forms no cavity distinct from the pre-
ceding, but is its continuation; the part espe-
cially designated thorax, however, is that which
is included from front to back between the
head and the beginning of the abdomen, and is
formed by the rings to which the extremities
serving for locomotion are attached. This mid-
dle portion of the general cavity of the body
contains almost the whole of the viscera. As
to the abdomen, it succeeds the last of the
thoracic rings, distinguishable by the presence
in it of the orifices of the male organs of gene-
ration ; the appendices attached to it do not
commonly attain any considerable size, and do
not serve in a general way as organs of locomo-
tion ; to conclude, nothing is found in its inte-
rior save muscles and the terminal portion of the
‘intestinal canal, the anal orifice of which exists
in the last of the abdominal series of rings.
These three portions of the tegumentary ske-
leton are not always equally distinct, and their
respective limits may even vary, for we occa-
sionally observe two or three of the foremost
thoracic rings detaching themselves, as it were,
from this region to which they properly belong,
to join or blend with the cephalic rings ; and
the same thing may be said in regard to the
segments of which each of the remaining divi-
‘sions of the body consists; we in fact know of
no specimen of a Crustacean in which the whole
of the rings are moveable upon one another ; a
certain number of them always appear to be-
come consolidated, and this union is frequently
so intimate that all traces of its existence are
obliterated, so that the section of the body
which results from this aggregation of rings
appears to consist of no more than a single

755

piece, and on a cursory view might be held to
be constituted by a simple ring. The shape
and size of these compound rings varies also,
circumstances which evidently depend on the
unequal development of the different pieces of
which they severally consist.

This consolidation of the rings occurs with
increasing frequency as we rise in the scale of
Crustaceans, and approach those the organiza-
tion of which is most complex; yet there are a
considerable number of species which form ex-
ceptions to this rule. The consolidation of the
rings also shows a tendency to take place in
the same order in which the different segments
of the tegumentary skeleton appear in the em-
bryo, that is to say from before backwards:
thus it is generally complete as regards the
cephalic rings; it is more frequent as regards
the foremost than the hindmost thoracic rings ;
and it but rarely occurs among the abdominal
rings

The differences which present themselves in
the dimensions and forms of the different rings
of the tegumentary skeleton, and which concur
so essentially in producing varieties in the ge-
neral form of the Crustaceans, also show a ten-
dency to become greater and greater as we as-
cend in the series of these animals, and com-
monly influence the cephalic rings in a degree
greater than those of the divisions situated
more posteriorly.

To conclude, it is also among the most ele-
vated Crustaceans that the tegumentary skeleton
is complicated in the greatest degree by the
evolution of apodemata in the interior of the
rings ; and further, it is in the cephalo-thoracic
portion of the skeleton only that these laminz
are encountered.

A few examples will render these general
rules more readily appreciated.

In the earlier periods of evolution of the
embryo of the river-crab, the whole of the rings,
which are even then apparent, are of the same
form and dimensions, and the segments, which
only appear at a later date, are at first similar
to what these rings were in the beginning.
This state of uniformity in the composition
of the whole of the constituent rings of the
tegumentary skeleton, which is invariably tran-
sient in the embryo, is not observed as a
permanent feature in any perfectly developed
Crustacean ; still there are several of these ani-
mals which are but little removed from it. In
the Branchipods, for instance, the body consists
of a long series of rings, having, with the ex-
ception of the very first, as nearly as possible
thesame form and the same dimensions. In the
Amphipods (fig. 382) the want of resemblance
between the different rings of the body becomes
much more remarkable: the first seven become
so completely united that they form a single
piece, in which no trace even of the lines of
consolidation remains, and the conical segment
which constitutes the head grows much more
slowly than the rest of the body, so that the re-
lative dimensions become smaller and smaller
as regards the head in proportion as the animal
approaches the adult age. The seven rings of
the thorax, on the other hand, continue per-

756 CRUSTACEA.

fectly distinct, and differ but little from one
another; and the seven abdominal rings, in
like manner, remain moveable, and only differ
from those of the thorax as they do from one
another by a relatively inferior degree of deve-
lopment. In the majority of the Isopods the
structure of the tegumentary skeleton is essen-
tially the same as in the Amphipods ; but there
occurs a greater inequality of development be-
tween the thoracic and the abdominal rings,
most of the latter remaining more or less in a
rudimentary state.

In the Apus and the Nebalia we conti-
nue to find the rings of the thoracic and abdo-
minal portions of the tegumentary skeleton
nearly equal in size and similar in form; but
the cephalic section, instead of presenting the
same conformation as these two portions of the
body, constitutes superiorly an immense shield,
which extends over the rings of the thorax and
conceals them. This dorsal shield or buckler,
which is denominated Carapace by zoologists,
also occurs among the whole of the Podoph-
thalmians, and more than all besides conspires
to give to these animals their distinguishing
peculiarities of shape. Inquiries, of which it
would be tedious to give a detailed account in
this place, have led us to discover that the
carapace of these Crustaceans is neither more
nor less than the superior are of the third or
fourth cephalic ring, enormously developed,
and which in attaining its large dimensions
laps over and modifies the conformation of a
greater or smaller number of the neighbouring
rings.*

In the generality of the Stomapods the cara-
pace does not quite cover and conceal the two
first cephalic rings, which indeed continue dis-
tinct and moveable; but in the whole of the
Decapods these rings cohere with one ano-
ther and with the following ones, and unite
more and more intimately under the carapace,
which then covers the whole of the head as well
as the thorax. In the Macroura the anterior
extremity of the carapace only extends over the
ophthalmic or first cephalic ring; but in the
Brachyura it bends around this ring so as to
include it, and to go to unite underneath with
the next segment. As we ascend in the series
of Crustaceans, we observe the carapace en-
croaching more and more upon the thorax.
In the Squille the three last cephalic and three
first thoracic rings are nearly lost by becoming
blended with those to which the carapace be-
longs; they scarcely retain any mobility, and
protected above by this shield, unite intimately,
and remain imperfect in their tergal portions ;
the four last rings of the thorax continue, on the
contrary, free, and are in almost every particular
similar to those of the abdomen. In the Mysis
this union of the cephalic shield with the seg-
ments of the thoracic division of the tegumen-
tary skeleton is carried further, for there are
not more than two of these rings which remain
distinct. But it is in the Decapods that the
carapace attains its greatest development, and

* See my Hist. Nat, des Crustacés, t. i. p. 23.

that its influence upon the evolution of the
thoracic segments is carried the farthest.

In these animals the framework of the body
does not appear at first sight to consist of more
than two portions, the one anterior, formed by
the carapace, and representing the cephalic and
thoracic segments conjoined ; the other poste-_
rior, formed by the abdomen. In reality, the
first fourteen rings of the body are covered by
this enormous buckler, and are so intimately
conjoined as to have lost all their mobility ; the
whole of the thoracic segments thus hidden
below the carapace, are connected with it in
their superior part, they are only joined with
one another underneath and laterally ; and their
tergal parts having, in consequence of this, be-
come useless, are no longer to be found, being |
in some sort replaced by the great cephalic |

i

ee ee ae

buckler; thus the whole of these rings, in con-
formity with this arrangement, are imperfect
and open above.

Hitherto we have not been able to deter-
mine whether the carapace of the Podophthal-
mia is formed at the expense of the third or
of the fourth ring of the tegumentary skeleton ;
but we have the strongest reasons to conclude
that this buckler is neither more nor less than
the dorsal are of one or other of these cephalic
rings, and not of the two conjointly. In fact
we can here demonstrate a composition analo-
gous to that which we have already pointed
out as characteristic of every arc, whether supe-
rior or inferior, of the different rings in their
state of complete development, to wit, a tergal
portion and two lateral or epimeral pieces. In
following the embryo of the River-crab in its
progressive stages of development, Rathke*
observed the carapace to be formed of three
pieces, which at length became consolidated
so as to form but one. In many of the Deca-
pods it is even easy to perceive this structure
or composition in the carapace of adults, inas-
much as there exist lines marking the conjunc-
tion, and aceurately indicating the respective
limits of the different pieces of which this great
dorsal plate is composed. :

The general form of the carapace depends in
great measure on the relative development of
these different pieces; in the Macroura the
tergal portion of the carapace extends but a
short way backwards, whilst the lateral or
epimeral pieces reach as far as the begin-
ning of the abdomen, and being no longer
kept at a distance by the tergum, meet in the
median line of the back, and are there con-
joined. In the Brachyura, on the contrary, the
tergal portion is that which is especially deve-
loped, so that it constitutes the whole of the
upper part of the carapace, whilst the lateral
pieces, thrust outwards and underneath, only
form a narrow band above the bases of the ex-
tremities. os oa

It is also in consequence of modifications
analogous to those on which the existence of the
carapace depends, that in other Crustacea the

"

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krebses, &c. Tr. in Annales des Sciences Nat, t, 20. =

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CRUSTACEA. 757

tegumentary skeleton presents the most singular
forms: thus among the Limmadia and the
Cypris, the pieces which are analogous to the
epimeral or lateral pieces of this cephalic
buckler, acquire a great extension, whilst the
tergal portion of the are to which they belong
continues rudimentary or proves entirely abor-
tive, so that they constitute two large valves
covering the whole body of the animal, and
bearing considerable resemblance to the shells
of certain acephalous Mollusks. The dorsal
lamine which in the Pandarus form appendices
on the back similar to Flytra, and those which
in the Anthostomata form a kind of sheath
around the posterior part of the body, are also
formed by the anomalous development of cer-
tain parts of both the dorsal and ventral arcs of
the two posterior thoracic rings.

The inferior arcs of the thoracic rings of the
tegumentary skeleton of the Decapoda, by
their intimate union, form a kind of ventral
shield, named sternal plastrum, upon which
lines of conjunction indicate the respective
limits of the greater number of the seginents, as
well as of the sternal and episternal pieces of
which these are composed. In the Decapoda
Macroura and Anomoura, this plastrum is in
general very narrow, but in the Brachyura it is
expanded to such a degree as frequently to con-
stitute a great and nearly circular disc. In the
whole ofthese Crustaceans, the lateral pieces of
the thoracic rings are conjoined, like those of
the inferior are of the same segments, and form
on either side of the middle portion of the
body a septum which is covered by the cara-
pace, and which is known among anatomists
under the name of the vault of the flancs. In
the Macroura this septum is nearly vertical,
but in the Brachyura it is oblique, or even
almost horizontal.

Lateral portion of the thorax of a Decapod.

a, the epimeral pieces united to form the vault of
the flancs; 6, the sternum; c, the apodemata
rising from the sternum and separating the in-
sertions of the legs.

Tt is among those Crustaceans the thoracic
rings of whose tegumentary skeleton blend or
become consolidated in this manner, and ac-
quire dimensions so considerable, that the struc-
ture of this portion of the frame-work also exhi-
bits the utmost extent of complication, in con-
sequence of the existence of large apodemata in
their interior. These septa are of two kinds;
the one, styled sternal apodemata, arise from
the lines of consolidation of the thoracic sternal
pieces; the other, named epimeral apodemata,

Vertical section of a portion of the thorax of one of
the Brachyura.

a, sternum, with a sternal apodema rising from it;
b, epimera from the inner surface of which an
epimeral apodema descends to join the sternal

apodema,: and thus form a septum between the
thoracic cells.

arise in a similar manner from the epimeral
pieces of the same rings. They are met with
among the Macroura and Anomoura, as well as
among the Brachyura ; but it is among these last
that they acquire their highest development;
their direction, vertical to the internal planes of
the rings, and the unions of those that rise from
the inferior aspect or floor with those that des-
cend from the arched superior surface, give rise
to the most singular combinations and forms, too
multifarious to admit of description in an
article of the extent of that in which we are
engaged, but the final effect of which is the
establishment of cells, divided from one an-
other by vertical septa, and corresponding to
each ring, and further intersected in the direc-
tion of their height, in a certain number of
species, and divided into two stages by means
of horizontal reduplications. -

It is within these different cells that the
muscles and principal vessels of the thorax are
lodged in the Brachyura; holes left at the con-
junctions of these lamine admit of the com-
munication of the cells two and two, either
through the vertical septa or through the hori-
zontal floors which divide the superposed cells,
and it is by means of these holes of conjunc-
tion that the anastomoses of the vessels of one
ring take place with those of the neighbouring
ring, as we shall see presently.

In the Macroura, again, this structure does
not occur, in consequence of which other means
of communication between the vessels of the
different segments require to be established,
the nature of which we shall also have to inves-
tigate before long. Generally speaking, the
disposition of these cells and of the septa
which form them varies considerably in the
Brachyura and the Macroura. Certain pro-
longations from the superior and internal angle
of the sternal apodemata, by their union in the
median line, after bending from before back-
wards, even form a longitudinal canal, which
extends through almost the whole length of the
thorax. This is the sternal canal, destined to
lodge the ganglionic nervous cord, and to serve
as the chief venous reservoir.

It has long been admitted as an axiom in
animal physics, that when any particular part
of the body acquires a very high degree of de-
velopment, certain other parts stop short of
their ordinary state of evolution, as if the former
had obtained their unusual increment at the cost

758

Thorax of the Astacus Fluviatilis, showing the dis-
position of the apodemata and the thoracic cells.

of the latter. This rule, which has been dis-
cussed by M. Geoffroy St. Hilaire under the
title of la loi de balancement organique, or law

of organic equivalents, is found to apply in the 6 \

present instance; for the Crustacea in which
the cephalic portion of the tegumentary skele-
ton is developed in the greatest degree, (viz.

the Brachyura) present the abdominal portion /

of the body of very small dimensions; whilst,
on the other hand, in the Macroura, or those

species in which the abdominal portion of

the body arrives at its maximum of develop-
ment, and performs a very important office in
the business of locomotion, the cephalic por-
tion is relatively greatly inferior in size.

With regard to its disposition the abdomen
is simple enough; the rings of which it con-
sists are in general moveable upon one
another, and even when they are consolidated,
present no apodemata projecting from their
interior. It is also deserving of remark that
the elementary pieces of the different rings are
not very distinct, and sometimes even appear
to be partially wanting.

Let us now go on to examine the portion
of the tegumentary skeleton belonging to the
extremities or that portion of the external
skeleton of the Crustacea which may be re-
garded as an appendage to the more essen-
tial covering of the head, thorax, and ab-
domen.

The Crustacea present this invariable cha-
racter, that the whole of the appendages belong
exclusively to the inferior arc of their tegu-
mentary rings, a point in which they resemble
the Arachnidans, and differ like these from
Insects, in which one or two of the thoracic
rings generally present a pair of extremities
supported by the superior arcs, as in the An-
nelidans, in which the dorsal segment of each
of the rings almost always carries a pair of
extremities fashioned in the same manner as
those belonging to the ventral arcs.* We
have already said that a pair of appendages
ought to be found attached to each ring; but
it very frequently happens that many of the
pairs are completely checked in their develop-

* Vide Annelida, p. 167.

spoken.

CRUSTACEA.

ment, or that the forms they assume, in har-
mony with the uses they serve, render |
them liable to be mistaken. It is very dif-
ferent in the embryo; here, in fact, as among
the simplest forms of the series, the whole
of the extremities are at first similar; and
it is only in consequence of ulterior develop-
ments that each pair finally assumes diver-
sities of form and character in relation with
the various functions to which they are espe-
cially destined.

In its most perfect state of development,
the extremity in the Crustacean consists of three
principal parts ; the stem (a), which is the most

Fig. 386. _ |

essential and most constant part, formed of a
variable number of articulations ; the palp (6),
an appendage which is detached from one of the
three first articulations of the stem, but almost
always from the first; and the whip (fouet ) (c),
which is sent off above and to the outer side of
the palp. It but rarely happens, however, that
these three organs exist simultaneously ; occa-
sionally not more than one of them can be
demonstrated ; and sometimes the whole three
are altogether wanting.

EEE EE se

i Se ee ee eee ae.

First cephalic ring of the Squilla separated from
the rest of the head, and bearing one of the
ocular peduncles.

The first ring presents no appendages except
in the very highest Crustaceans, and even then
they are simple in their composition, and never
exhibit more than the stem, which arises from
a more remote check to their development
dating from about the commencement of their
embryonic evolution; these are the ocular pe-
duncles. veh;

The second and third pairs of extremities —
constitute the antenne. These are wanting in-
a certain number of the inferior species, and
even in those among which they occur, they
vary considerably in their structure: they may
for instance present one only, or two, or the
whole of the three elements of which we have

But as the three first pairs of ap-

CRUSTACEA.

Fig. 388.

a, second thoracic ring of the Squilla; b, one of
the small antennz.

ndages belong especially to the function of
terion. and Po ani | have to revert to
these at a later period, and give an ample de-
scription of their structure, we shall not enter
upon this subject farther at present.

Third and fourth cephalic rings of the Squilla:
_ @, carapace; 6b, one of the posterior antennz ;
e, one of the mandibles.

The eleven pairs of appendages which suc-
ceed are variously apportioned between the
ace of digestion and locomotion, to which
last five hindmost pairs are entirely dedi-
cated in the Decapods. In other Crustacea,
again, the first pair only is set apart in an
especial manner for the office of mastication,
all the others then serving for locomotion, and
this pair is in consequence very generally de-
scribed under the name of mandibles; very
commonly one and even two other pairs are

759

added to this first pair, and these are desig-
nated jaws or maville. In the majority of
instances, moreover, the three succeeding pairs
assist the three preceding; and as they are
frequently more especially apportioned to loco-
motion, the two last in particular, whilst in
some cases they serve for the two functions at
one and the same time, they have been de-
signated by anatomists and naturalists the
maxillary limbs (pieds-machoirs): these we
shall describe when we come to speak of the
apparatus of digestion.

As to the five pairs which we have already
mentioned as essentially ambulatory (see
Jig. 382), they present in the Brachyura no
more than a simple stem, composed of six
articulations ; whilst in the Astacus and allied
genera, we find a flabelliform appendage or
whip, dedicated especially to the purposes of
respiration, and in the Penee the three sorts
of appendages existing simultaneously. By-
and-by, when speaking of respiration, we shall
see how it happens that in a great number of
these animals the whip of the thoracic extremities
assumes a vesicular structure, and becomes
the organ of this important function.

The same peculiarity is observed in the
appendages of the abdominal extremities
of a great number of species; but among
the members of the most elevated tribes,
these appendages are but very slightly
developed, and appear to have no other
use than to attach the eggs along the in-
ferior surface of the abdomen.

Abdomen of the female Maja
Squinado.
a, the abdominal appen-
dages,

We shall not at present enter upon the con-
sideration of the forms of the thoracic and
abdominal extremities, having it in view to
take up the subject when we come to examine
these appendages as the organs of prehension,
and as fulfilling important offices in locomotion,

Before quitting the study of the tegumen-
tary skeleton, to go on to that of the extre-
mities considered especially as the organs of
locomotion, we think it necessary to say a few
words upon the moult or process by which the
tegumentary covering of the whole of the Crus-
tacean is cast off and renewed.

The necessity for this operation is a con-
sequence of the very nature of the envelope:
like every other epidermic covering, the pro-
duct of secretion, the shell of the Crustacea is
closed in on every side, and can only increase
in thickness, so that all growth would be pre-
vented in the body of these animals were they
denied the power of freeing themselves from
time to time of their prison. Accordingly they
have this power; and as might have been ex-
pected the shell is cast by so much the more
frequently as the animal is younger, inasmuch

700

as the growth is then most rapid; as many
as eight changes of the tegumentary envelope
have been observed to take place in the course
of seventeen days in the young Daphnia; whilst
in adult Crustacea the change is not in general
effected oftener than once a year.

Réaumur watched the phenomenon through
its whole course, and has noted it with all its
details as it occurs in the Astacus fluviatilis.*
It takes place in this species towards the end
of summer or beginning of autumn. A few
days of fasting and sickness precede it, during
which the carapace becomes loosened from the
corium to which it adhered, and which im-
mediately begins to secrete a new one, soft
and membranous at first, but soon becoming
harder and harder, and finally completely cal-
careous. In this way the animal before long
finds itself free from all connexion with its
old envelope, and it has only to make its
escape. This last operation is announced by
symptoms of inquietude. The creature rubs
its legs one against another, and then throwing
itself upon its back begins to shake itself,
puffs itself out, so as to tear the membrane
which connects the carapace with the abdo-
men, and to raise the carapace itself. After
sundry intervals of rest and agitation of longer
or shorter duration, the carapace is raised com-
pletely ; the animal extricates its head, its eyes,
and its antenne. The operation of freeing
its extremities appears to be the most difficult,
and would even be impossible did not the
solid covering of these parts split longitudi-
nally; but in spite of every assistance, it not
unfrequently happens that the animal leaves
one or two of its limbs impacted within the
old sheath, and occasionally even perishes
through inability to escape completely from its
shell. The abdomen is the last division of
the body which clears itself of the old enve-
lope. All the parts of the tegumentary ske-
leton which had only been separated from one
another, without however having undergone
any softening, or fracture, or separation, fall
one upon another in resuming their old posi-
tions, so as to represent the complete external
form of the creature with the whole of its
solid internal as well as external parts; even
the eyes, the antenne, and the thoracic cells
formed by the sternal and epimeral apodemata,
may be distinguished. The operation now
described does not in general occupy more
than half an hour in the performance; and
only two or three days, or even no more than
four-and-twenty hours are required to convert
the soft and membranous envelope with
which the corium or naked body of the
animal is surrounded, into a firm calcareous
covering similar to the one which has just been
got rid of. The new envelope presents the
same appendages as the former one, even the
same hairs; but these, instead of being con-
tained within the old ones, as Réaumur ima-
gined, exist ready formed in the new envelope,
but turned in towards the interior, like the
fingers of a glove turned in upon themselves.

* Mémoires de ’ Academie des Sciences, 1718.

CRUSTACEA.

There are some species, such as the Crabs
and the Brachyura generally, in which the
carapace presents a considerable expansion on
either side, forming two large compartments
in which the greater mass of the thoracic vis-
cera is contained. Under these circumstances
it would be impossible for the animal to escape
from its dorsal covering by the relatively in-
considerable opening which this part presents
on its inferior aspect. This renders it neces-
sary that the carapace, instead of being cast
off by simply rising in a_ single piece,
should give way and separate in some direction
or another, and this it does by splitting along
the curved lines, extending on either side from
the mouth to the origin of the abdomen, in the
course of which the epimeral pieces cohere
with the dorsal one.*

The time occupied in the business of throw-
ing off the shell varies considerably in dif-
ferent species; it is also dependent on at-
mospheric influences. It is the same also,
in regard to the number of days necessary to
give to the new epidermic layer the consistency
of the old tegumentary covering. A general
remark, however, and one which is applicable
to the whole of the species that have been
duly observed, especially those that are found
along the shores of France, is this,—that the
period which precedes as well as that which
follows the change of the shell is one of rest-
lessness and evident illness. The muscles of
these creatures are then flaccid, the flesh is soft
and watery, and as food they are rejected as
tasteless and held unwholesome. This would
not appear to be the case with the Land-crab,
however, according to the statements of several
travellers, who inform us that the flesh of this
species is never in greater perfection than during
the season of the moult.

A phenomenon, which has some analogy with
the renovation of the tegumentary skeleton,
but which is much more curious, is the repro-
duction of the legs of these animals. Most
Crustacea cast off their claws very easily and
without apparent pain; the separation always
takes place in a determinate point near the
basis of the member (in the second articula-
tion), and is soon followed by the formation
of a cicatrice, from the surface of which sprouts
out a small cylindrical appendage ; this shortly
after presents distinct articulations, and re-
sembles in miniature the organ it is destined
to form, but its growth is slow, and it does not
for some time attain its full size. If one of
the limbs be severed in any other part, the
wound continues to bleed, and no renovating
process begins unless the animal, by a violent
muscular contraction, succeeds in breaking off
the stump in the articulation above mentioned.

The kind of solid sheath formed by the
tegumentary skeleton of the Crustacea, and
which includes in its interior the whole of
the viscera and other soft parts of these ani-

mals required to be so constructed as not to —
oppose locomotion; consequently there exist, —

* Collinson, Phil. Trans. 1746 and 1751 ;
Nat. des Crustacés, t. i. p. 56.

Hist,

CRUSTACEA. 761

either between the different rings of the body
or the various constituent elements of the
limbs, articulations destined to admit of mo-
tion to a greater or less extent, between these
different pieces. The structure of these arti-
culations is of the most simple kind; the
moveable piece rests upon that which precedes
it by ba higge-tike joints situated at the two
extremities of a line perpendicular to the plane
in which the motion takes place. In the in-
ternal portion of the edge of the moveable
piece pe sang between the joints, there exists
a notch of greater or less depth, destined to
admit of flexion, whilst on the opposite or
external side, the same edge generally glides
under that of the preceding piece. This kind
of articulation, whilst it is the most favourable
to precision of movement and to strength, has
the disadvantage of admitting motion in one
plane only; therefore the whole of the rings
of the body, the axis of motion being entirely
rallel, cannot move save in a vertical plane ;
ut nature has introduced a kind of corrective
of this disadvantage in the structure of the
limbs, by changing the directions of the arti-
cular axes, whence ensues the possibility of
general motions being performed in every di-
rection. Between the two fixed points two
opposed empty spaces are observed, left by
rings severally, and destined to admit of
the occurrence of motions of flexion and ex-
tension. The tegumentary membrane which
fills it never becomes encrusted or calcareous,
but always continues soft and flexible.

The tegumentary skeleton, of which we
have thus taken a summary view, supplies the
apparatus of locomotion with fixed points of
action as well as with the levers necessary to
motion. The immediate or active organs of
this apparatus are the muscles, the colour of
which is white, and the structure of which
presents no peculiarity worthy of notice. They
are attached to the pieces which they are re-
quired to move either immediately, or by the
intermedium of horny or calcareous tendons,
which are implanted upon the edge of the
segment to which they belong. To the
fixed point they are most commonly at-
tached immediately. Their structure is sim-
ple, and each segment, in fact, as has al-
ready been said, being contrived to move
in one fixed and determinate plane, the mus-
eles which communicate motion to it, can
constitute no more than two systems anta-

‘gonists to each other, the one acting in the

sense of flexion, by which the segment moved
is approximated to that which precedes it,
the other in the sense of extension, by which
the segment is brought into the position most
remote from the centre of motion. The mus-
cles that produce these opposite effects, as
might have been concluded, are found im-
planted into the opposite arms of the lever
upon which their energy is expended.

- The motions in flexion tend universally to
bring the extremities and the different rings
towards the ventral aspect of the body; it is

_ consequently upon this aspect that the flexor

muscles are inserted, and these are in general
VOL. :

the more powerful. On the contrary, and in
accordance with the nature of the motion pro-
duced, it is upon the superior or dorsal aspect
of the segments that the extensor muscles are
attached. In the trunk the two orders of mus-
cles generally form two distinct layers, the one
superficial, the other deep; the former thin and
sometimes absent, the second, on the contrary,
very powerful wherever powerful motions are
required. The muscles generally extend from
the arc above to the one immediately below,
passing for the most part from the anterior
edge of the upper to the anterior edge of the
lower segment. The extent and the direction
of the flexion of which any segment is sus-
ceptible, depend on the size of the inter-
annular spaces above or below the ginglymoid
points; and as these spaces are in general of
considerable magnitude on the ventral aspect,
whilst the superior arcs are in contact and can
only ride one over another in a greater or less
degree, it is only downwards that the body can
be bent upon itself; while upwards, or in the
sense of extension, it can hardly in general be
brought into the horizontal line.

Thus far what has been said applies more
especially to the rings of the body, but the
extremities present nothing that is essentially
different either as regards the mode in which the
tubular segments are articulated to one another,
or as regards the mode in'which the muscles
are inserted. Each of these indeed having but
one kind of motion, and even that very limited
In its extent, nature has aided the deficiency,
as has been stated, by increasing the number
of articulations, by which extent of motion is
conferred, and in varying the direction of the
articular axes, an arrangement by which the
animal obtains the ability of moving in every
direction, but at the expense both of power, ra-
pidity, and precision in its motions. Each seg-
ment of a limb encloses the muscles destined
to move that segment which succeeds it, un-
less it be too short and weak for this end, in
which case the muscles themselves have their
origin at some point nearer to the median plane
of the body. As a general law the muscles
are observed to be more powerful in proportion
as they are nearer to the centre, which is to be
explained by the fact that each motion they
then communicate is transmitted to a larger
portion of a limb, to a lever longer in that
sense in which it is disadvantageous to the
power. Occasionally, however, the two last
segments of a member are converted into a
sort of hand, and in this case the penul-
timate segment sometimes includes a mus-
cular mass which may surpass in power the
same system in the whole of the limb besides.
Those muscles that put an extremity generally -
into motion, are attached to the sides of the
thoracic cavity, and the apodemata supply
them with surfaces of insertion of great extent
and very favourably situated as regards their
action. They occupy the double rank of cells
formed by these lamine; but they vary too
much in their mode of arrangement to admit
of our saying any thing general upon this head.
The motions of translation, or from place to

3D

762

place, the only kind upon which it seems neces-
sary to say anything here, are effected in two
modes, either by the alternate flexion and ex-
tension of the trunk, or by the play of the limbs.

In those Crustacea which are formed essen-
tially for swimming, the posterior part of the
body is the principal agent in enabling the
animal to change its place; but here the mo-
tions, instead of being lateral, are vertical ;
and instead of causing the creature to ad-
vance they cause it to recede: it is by bend-
ing the abdomen suddenly downwards, and
bringing it immediately under the sternum,
that it strikes the water, and consequently by
darting backwards that the animal makes its
way through that liquid. From what has now
been said it may be imagined that the Crustacea
whose conformation is the best adapted for
swimming, have the abdomen relatively largely
developed, and this is, in fact, what we always
observe; the Amphipoda and Decapoda ma-
croura are examples; whilst, in the walking
Crustacea, such as the Crabs, the Caprella,
the Oniscus, &c. this portion of the body
attains but very insignificant dimensions.

In the swimming Crustacea the appendages
of the penultimate segment of the abdomen
also become important organs of locomotion,
inasmuch as they for the most part terminate
in two broad horizontal plates, which, with
the last segment, also become lamelliform, con-
stitute an extensive caudal fin arranged in the
manner of a fan.

We have already said that the thoracic ex-
tremities alone constitute true ambulatory
limbs. When destined for swimming only,
their segments are lamelliform, and the palp,
as well as the stem, contributes to form the
kind of oar which each of them then con-
stitutes. The Copepoda supply us with in-
stances of thoracic extremities particularly
destined for swimming, and a correspondin
structure is observed in certain Podophthalmia,
such as the Mysis. (See fig. 386.)

To conclude, this stemmatous portion of the
thoracic extremities, whilst it still preserves
the general form which we have assigned it, is
modified in some cases to serve for walking
as well as swimming, or to aid the animal as
an instrument for burrowing with facility, and
making a cavity for shelter among the sand.
Thus in the Decapods that burrow, the last seg-
ment of the tarsus assumes a lanceolated form,
and in the swimming Braehyura, the same
segment, especially of the last pair of extre-
mities, appears entirely lamellar.

We have only further to add that in a great
number of species one or several pairs of the
thoracic extremities are modified so as to
become instruments of prehension; some-
times it is the last segment of the limb which,
acquiring more than usual mobility, bends in
such a manner as to form a hook with the
preceding segment ; sometimes it is this penul-
timate segment which extends below or by the
side of the last, so as to form a kind of im-
moveable finger with which it is placed in
opposition. in the first instance these instru-
ments are denominated subcheliform claws, in

CRUSTACEA.

the second chele simply, or cheliform claws.
We shall revert to these organs when we come
to treat of the apparatus of digestion.

§ 2. Apparatus of Sensation.
_ A. Nervous System.—When endeavouring
to form as accurate and complete an idea as
possible of the tegumentary skeleton of the
Crustacea, we began by studying it in its suc- —
cessive states of development in the embryo,
and then compared the various stages of
transition in which it met our observation,
with the permanent conditions in which it
finally remains in the organic series, classed
in conformity with the structural affinities of
the different genera. In the study of the
nervous system, upon which we are now about
to enter, the same mode of proceeding will
lead us to analogous results.

The deep situation of the nervous system,
and the transparency of the filaments and
various masses which compose it, are each
obstacles to its observation until it has arrived
at a somewhat advanced stage of development.

It was, in fact, only after the sternal canal had
begun to appear under the form of an enlarge-
ment, sieal by a double series of tubercles,
which prove to be the rudiments of the motor
muscles of the extremities, that Rathke* was
able to catch a sight of the earliest traces of the
nervous system in the Astacus fluviatilis, and
even this was no more than the portions be-
longing to the head and thorax. All that can
be seen then amounts to very little; in the part
behind the mouth, eleven pairs of whitish spots
are arranged in two longitudinal series perfectly
distinct from one another, and situated on either :
side of the mesial plane. It is otherwise easy
to perceive that a pair of these spots corres-
ponds to each ring, setting out from, but in-
cluding those of the mandibles. Neither the
cesophageal cords nor the cephalic ganglions
are then distinct.

At a later period these rudiments of the
nervous system undergo remarkable modifica-
tions. The six first ganglions of each series
approach those that are symmetrical with them
severally, so as to become united along the
median line, and, at length, to form a simple
chain of ganglions corresponding to the six
rings, whose appendages are the mandibles ;
and the five pairs of maxillary extremities.
The ganglions, on the contrary, which corres-
pond to the five posterior thoracic rings, continue
to form a double series. During this time the
sternal canal is evolved so as to surround the
nervous system with a firm and solid sheath.
At a period of the incubation still farther ad-
vanced, that is to say, during the time which
elapses from the birth of the young Crustacean
to that at which it attains its full growth, new
and important changes take place. First, the
four most anterior csophageal tubercles, in
other words, those which correspond to the
mandibles, to the jaws, and to the first pair of ©
maxillary limbs, become united, by approach-_
ing one another along the mesial line, so_

a a

e
* Untersuchungen tiber die Bildung des Fluss-
krebses. ) ae

G. den

4
a
4

CRUSTACEA. 763

as finally to constitute a single continuous
mass only. The same thing happens in re-
gard to the fifth and sixth, which soon form no
more than a single ganglion. As to the other
pairs they always remain completely distinct,
and some way from one another.

Thus the study of the gradual evolution of the
nervous system in the Astacus fluviatilis, al-
though by no means belonging to the type in
which this system is most completely developed,
yresents us with three distinct and successive
Sri which we shall find reproduced in the
most perfect manner in the natural series of
genera, and which will put us into a position
to give a satisfactory explanation of those very
striking variations in the organization which we
shall encounter.

These are, in the first place, the isolated for-
mation of the nervous centres, independently
one of another. We now acknowledge this
independence of the several organs at the
moment of their appearance, and their ulterior
conjunction is one of the most interesting and
important facts with which modern science has
been enriched ; it poston et cant a

petal development, as it has been established by
M. Serres.

In the second place a tendency to conjunc-
tion by a motion transversely.

Lastly, a second motion in the line of the
axis of the body, the effect of which is the
concentration definitively of a greater or smaller
number of nervous centres primarily indepen-
dent of one another.

The Talitrus exhibits in the Fig. 391. |
most striking manner the firstof wy ¢
the three dispositions which we cf F
have mentioned from the mo-
ment at which ~ ~ pe sys- |
tem a . In this genus, in
fact, ieaeninive on either side
of the median line a ganglionic |
chain, formed by the conjunc-
tion of the nervous centres,
extremely simple in their struc- &
ture, and flattened and some- ()
what lozenge-shaped in their
outline.* There are thirteen
pairs thus constituted, corres- |
ponding to the thirteen seg-
ments which enter into the com-
position of the whole body. The
two nuclei of each pair com-
municate together, in the same [
manner as each pair is con-
nected with that which succeeds, |
and with that which precedes it,
by means of medullary cords in Wy
the first instance, and longitu- je jj0"7 ee
dinal cords in the second. In | Soohalie cand
all essential particulars each pair gija; 4, me-
is a counterpart of any and dullary cords
every other pair, without even uniting the first
excepting the cephalic ganglion, apconeoms pair
and it is with difficulty that the °f $°"8!!-

* Vide Recherches Anatomiques snr le Systéme

Nerveux des Crustacés, par M M. Audouin et Milne
- ial Annales des Sciences Naturelles, tom.

thoracic pairs are seen to be in a slight degree
larger than the others. At a somewhat greater
distance forward from the cesophagus, too, than
usual, we observe the cephalic ganglion, which
sends branches to the antenne and eyes, and
the nervous cords by means of which it commu -
nicates with the ganglions-of the first thoracic
rings. These cords, having the cesophagus inter-
posed between them, are helda little farther apart
than the other branches, which, establish com-
munications between the different succeeding
pairs of ganglions in the longitudinal direction.

Already in the Oniscus asellus* and in the Cy-
amus cetit we find the ganglionic cord, double
in its middle portions, simplified at its opposite
extremities in such wise that the ganglions of
the first and of the last pairs are single. This
commencement of approximation coincides in
other respects with an incipient approximation
in the longitudinal direction, for, to the four-
teen segments of which the whole body consists,
we find no more than ten pairs of ganglions
apportioned.

is tendency to centralization is still more
conspicuous in the Phyllosoma.{ Here we
discover the two cephalic nuclei united by their
internal angle, without, however, their state of
doubleness being thereby obscured. It is the
same with the first pair of thoracic ganglions,
from which they are separated by the whole
length of the great oval lamina which supports
the cephalic appendages and is traversed
lengthwise by the nervous filaments which
embrace the esophagus. The ganglions of the
second pair, although rudimentary, are still
united immediately, as are those of the third
pair also. Those of the six suc-
ceeding pairs, on the contrary,
only communicate by means of
a transverse but thick and short
commissure, so that it gives to
the connexion established be-
twéen the nuclei of the several
pairs, the appearance of a more
immediate conjunction than ac-
tually exists. To conclude, the
abdominal ganglionsare perfectly
distinct, and those of the several
pairs are only connected by
means of extremely slender fila-
ments.

In the Cymothoa the union of
the medullary nuclei in the trans-
verse direction is complete, and
all we perceive is a single series
extended along the median line
through the whole length of the
body. This is similar to the
nervous system of the Talitrus of tiolymacdon.
conjoined longitudinally; with
this difference, that the longitudinal filaments
uniting the ganglion have continued distinct,
as if to testify, by their doubleness, to the
mode of formation of the single ganglionic cord.

* Cuvier, Legons d’Anatomie comparée, t. ii.
p- 314. . :
+ Treviranus, Vermischte Schrifteh anatomischer
und physiologischer inhalts, Band 2. Heft I.
¢ Audouin et Edwards, loc. cit.
3D 2

764

But it is more especially in the types which
still ask our attention, that we ule the
system of centralization pushed yet farther by the
actual conjunction of the nuclei, which we have
hitherto only seen approximated to one another,

Fig. 393.
b

4 \ ~ O ‘
or Ni
} ;

i

Nervous system of the Astacus Marinus, or Sphinx
Ligustri.

_ CRUSTACEA.

-of communication are entirely consolidated

_ origin to five pairs of nerves and to two cords,

in consequence of their gliding or encroaching,
as it were, upon the medianline. 2

- The Lobster ( Astacus marinus ) (fig.393) pre-
sents us with another step in the system of cen-
tralisation. Here, in fact, the longitudinal cords

along the median line through the whole of the
abdomen, although they are still to be found —
double in the thorax. Moreover, the first thoracie
ganglion (¢4), and the last of the abdominal __
series of ganglions (a5), are conspicuously
formed by the reunion of several distinct ner-
vous centres, in the way we have already indi-
cated as happening, although in a minor degree
and less perfectly, in the Amphipoda and the
Tsopoda. Before we pass, however, to the con-
sideration of more complicated systems, we shall
pause a moment to describe somewhat at length
the one which we have but just mentioned,
the more as it is among the number of those
which have been most attentively studied.

The cephalic ganglion (g', fig. 393), situated
above the base of the internal antennz, is of con-
siderable size, and appears to be simple ; it gives

which connect it with the rest of the ganglionic —
nervous system. The first of these pairs (0)arises

from its anterior edge: this is the optic pair,

which, after having penetrated the peduncles of

the eyes, increase in size, and traverse a mem-

branous diaphragm, which may be likened to

the sclerotic coat.

The second pair of nerves correspond to the
ocular motors; they run parallel to the pre-
ceding pair, and are distributed to the muscles
of the eyeball.

The third pair proceed to the internal anten-
ne (b); but before they enter these appendages
they send off a branch to the muscles which
move them. A like ramification is sent off
from the principal trunk to each of the rings of
which these antenne are composed, and the
nerve ends by becoming bifurcated, in order to
penetrate the two filaments in which the an-
tenne terminate.

The fourth pair of nerves (e) are distributed to
the tegumentary membranes of the anterior
extremity of the animal. Behind the fourth a
fifth pair is seen (d), which proceeds anteriorly to
the fourth pair almost immediately after its
origin, sends one branch to the cake-like organ
of doubtful function which covers the ear, a
second branch to the organ of hearing itself,
and finally terminates ina trunk of considerable —
size, which traverses the external or second —
antenna through its entire length. vi

A sixth pair is destined to establish con- —
nexions between the cephalic ganglion and the —
first of the thoracic ganglions, after having sur-
rounded the cesophagus; but instead of ap-
pearing as simple nervous cords through
whole length, as in types which we hai
hitherto studied, each of them presents :
enlargement in its middle, which is neithe
more nor less than a ganglion, from which thi
is sent off, first, a nerve that proceeds to ©
mandibles (/'); next, a gastric nerve (g), of lar
size, which gives many filaments to the coats
of the stomach, and finally anastomoses wit

4 F
3
4 4
+
as
a
3

ee Se a re ee

CRUSTACEA. 765

the corresponding cord of the opposite side ;
after this the two forma single nerve, which
by-and-by presents an enlargement having
the appearance of a small median ganglion,
and then remounts upon the dorsal aspect
of the stomach to ramify there, and ultimately
to lose itself upon the intestine(h). Behind
the stomach a transverse cord (7) is seen,
which connects the two nervous filaments, and
appears to be the cord of communication be-
tween the ganglion of which mention has just
been made, pushed backwards, in the same
way as the ganglions themselves have been
kept apart, to wit, by the resistance of the
cesophagus, interposed at the time when that
process is going on by which the pairs gene-
rally are approximated in the course of the
median line.

_ The first of the thoracic nervous masses (t')
1S oval-shaped, and gives origin to ten pairs of
nerves, five of which issue from the anterior
aspect. The first run to the mandibles and
to their muscles; the second to the auditory
apparatus ; the third to the first jaw, the fourth
to the second jaw; the fifth to the cells of the
flancs, to the muscles and neighbouring inte-
guments ; the sixth and seventh arise from the
inferior aspect of the nervous mass to proceed
to the maxillary feet; the nerves of the eighth
pair are extremely slender, and are distributed
to the muscles of the thorax; the two succeed-
ing pairs belong to the third pair of maxillary
extremities ; lastly, two cylindrical cords arise
from the posterior extremity of this nervous
centre, and connect it with the second thoracic
ganglion, giving origin themselves in their
passage to a pair of extremely minute filaments,
which run to be distributed to the muscles of
the thorax.

This first thoracic nervous mass represents,
therefore, the five pairs of ganglions which
follow the mandibular ring, and must be viewed
as resulting from the concentration of the five
pairs of medullary nuclei belonging to the five
rings which bear the accessory masticatory or-
gans. In the adult Lobster the different ele-
mentary constituents are not traceable, and the
whole mass appears to be composed of no more
than two ganglions closely connected in the
median plane ; but in a species very nearly allied,
namely, the River-crab (Astacus fluviatilis ),
very obvious traces of the existence of several
medullary nuclei can always be demonstrated
in its interior. The five pairs of ganglions
that follow (¢?—7°), and that belong to the five
last thoracic rings, have, on the contrary,
continued distinct; although simple, these
nervous centres still exhibit manifest indi-
cations of their composition severally by two
nuclei; from either half we have a cord of
communication sent off, similar to those

which we have already pointed out as exist-

ing between the first and second thoracic
ganglions; the whole of these inter-ganglionic
cords are in contact along the median line,
except the penultimate or antepenultimate

pairs, which are separated from one another

y the sternal artery, in the same manner as

those of the head are kept asunder for the pas-
sage of the cesophagus.

Each of these five thoracic ganglions sends
two pairs of nerves to the ambulatory extre-
mities which correspond to them severally.
Of these two nerves, the posterior and larger
sends branches to the basilar articulations of
the extremities; the anterior, again, distributes
twigs to the muscles of the flancs; the two
soon anastomose, and form a single trunk
before penetrating into the extremity itself,
which then traverses the whole limb, send-
ing a branch to the muscles of each arti-
culation.

The abdominal ganglions (a'—¢®) are smaller
than the preceding ones, and are connected by
simple longitudinal cords. They also supply
two pairs of nerves, the one destined to the
muscles of the abdomen, the other to the ap-
pendages of the ring with which it corresponds.
As in the thorax, nervous fibres, distributed to
the median and superior part of the abdomen,
are observed proceeding from the cords which
establish a communication between one gan-
glion and another.

The last ganglion (a@%), which appears
to be made up of the medullary nuclei be-
longing to the sixth and seventh segments of
the abdomen, gives origin to four pairs of
nerves, which run to the penultimate articu-
lation of the abdomen, and to the last, which
is of a flattened form, and along with the ap-
pendages of the former constitutes the kind of
horizontal oar which terminates this part of the
body.

Such is the nervous system in the Lobster.
If we study it in the Palemon, we shall find
precisely the same elements, but with a still
higher degree of centralization, for the ganglia »
of the three lowest thoracic rings are conso-
lidated into one, and situated much forwards,
so that the nerves to which they give origin
have to pursue a very oblique course, in order
to reach the parts to which they are distributed
respectively. The ganglion of the second pair
is isolated ; that of the first pair of ambulatory
extremities blends and is confounded with
that of the third pair of maxillary limbs. The
five anterior pairs of cesophageal ganglions, in
fine, are united into a single nervous centre.
There are consequently, properly speaking, no
more than four medullary masses in the whole
length of the cephalo-thoracic portion of the
Palemon; and even these are very close to
one another, and all but united, their longi-
tudinal commissures being thick and simple,
and bearing as close a resemblance to constric-
tions in a single nucleus as to bands of
communication between distinct nuclei. The
fourth of these four ganglions presents a longi-
tudinal cleft through its centre, a structure
which is easily explained by the presence at
this point of the sternal artery, which existed
there before the ganglia became conjoined in
the course of the median line, and necessarily
opposed a merely mechanical obstacle to their
entire union.

In the Palinurus the whole of the thoracic

766
ganglia, strictly speaking, are united
into a single mass of a greatly elon-
gated form, and presenting a little
way back, like the fourth ganglion of
the Palemon, a cleft for the trans-
mission of the sternal artery.

The transition
from the Deca-
poda Macroura
to the Brachyura
takes place by
the Homola, and
certain Anomou-
ra,* in which the
constantly §in-
creasing concen-
tration of the
thoracic nervous
centres coincides
with the almost
rudimentary state
of the abdominal
ganglionic sys-
tem, which is
here reduced, to
a kind of median
trunk without en-
largements.

This, too, is

‘ the disposition

Cephalo-thoracie r-

ne of the ATE AR presented by the

system of the Pali-nervous system
nurus Vulgaris. in the Carcinus
menas among

the Brachyura, with this difference
only, that the medullary nuclei are
rather closer to one another, and
more intimately connected.t+ The tho-
racic ganglion has the form of a ring, the cir-
cumference of which gives origin to the nerves of
the thoracic appendages. The single abdomi-
nal cord is in its rudimentary state, in obvious
relation with the abdomen itself, and therefore
reduced to very insignificant dimensions.

It is in the Maja,f in fine (fig. 395), that the
nervous system is found in its highest degree of
centralization; for the elements of which the
two masses there encountered are composed, are
so intimately conjoined, that no trace can be
found of their ever having existed indepen-
dently, although among neighbouring genera
several of them may still be discovered isolated-
ly. The cephalic ganglion (a) is a sufficiently
faithful counterpart of that of the Lobster.
The nervous cords (g) which connect this first
portion of the system with the thoracic portion
also present the same arrangement as in the Lob-
ster ; there are similar mandibular nerves, a like
gastric pair, the same transverse band (g’) behind
the esophagus, &e. But the thoracic ganglion
(2), instead of the ring which it presents in the

* Vide Rech. sur l’organiz. et la classific. des
Crustacés Decapodes par M. Milne Edwards; An-
nales des Sciences Naturelles, t. xv.

+ Cuvier, Legons d’Anatomie Comparée, t. ii. p.
314.

¢ Audouin et Edwards, loc. cit.

CRUSTACEA.

J s = ~ S
tS
ag — |

a E

L,'

7 rus a.

iy
Ye

uf)

———— Se

Nervous system of the Maja Squinado.

a, cephalic ganglion; 6, optic nerves; c, oculo-
motor nerves; d, nerves of the antennule; e,
fourth pair of nerves belonging tothe integuments 5
f, nerves of the exterior antenne; g, medullary
cords uniting the cephalic and thoracic ganglions ;
g, transverse cord; h, mandibular ganglion; /’,
small nerve belonging to the mascles of the
mandible; i, stomato-gastric nerve; hk, lateral
branches of the stomato-gastric nerves; J, tho-
racic ganglion; m, nerves of the maxilla; n,
nerves of the first pair of legs; 0, abdominal
nerve; p, cells of the flancs; q, arch of the
flancs, .

Carcinus meenas, here appears as a solid circu-
lar and flattened nucleus giving origin to the
whole of the nerves of the thorax and abdo-
men, which radiate from it to the number of
nine pairs, and one azygous nerve situated in the
median plane. There is nothing very remarkable
in the distribution of these nerves, unless it be
that several pairs,and among the number the first _
and second, are distributed simultaneously to —
several rings, which proclaims that in the
species which engages us the work of con-—
centration has extended from the ganglions to
the nervous cords. Let

Any farther detail in addition to what hi
now been said would contribute little to our
essential knowledge of the nervous system.
We have traced it from its commencement In

CRUSTACEA.

a series of independent centres, and we have
seen these becoming successively conjoined in
a greater and greater degree, as if in obedience
to a law of attraction, whose tendency was to
collect these various nuclei from every part of
the body towards a common centre. ‘This dis-
position to centralization has, in its turn, given
a satisfactory explanation of the most remark-
able differences observed in the disposition of
the ganglions and of the nervous cords
among the different types of the class, however
dissimilar these may be one from another.
We may, therefore, here conclude, as has been
done already in my work especially devoted to
this subject, that the nervous system of the
Crustacea consists uniformly of medullary
nuclei (ganglions), the normal number of
which is the same as that of the members or.
rings of the body, and that all the modifica-
tions encountered, whether at different periods
of the incubation, or in d'fferent species of the
series, de, especially on the approximation,
more or complete, of these nuclei, (an ap-
proximation which takes place from the sides
towards the median line as well as in the longi-
tudinal direction, ) and to an arrest of develop-
ment occurring in a variable number of the
nuclei.

In a paper upon the nervous system of the
Lobster recently published,* Mr. Newport
mentions an interesting fact hitherto overlooked
by anatomists. He found that the double
ganglionic chain of this Crustacean is composed
of two orders of fibres, forming distinct and
superposed fasciculi or columns, which the
author designates columns of sensation and of
motion, following the analogy which he be-
lieved he had traced between these fasciculi
and the anterior and posterior columns of the
spinal cord of the higher animals. The fas-
ciculi here indicated are but indistinct in the
interganglionic cords, but become extremely
apparent in the ganglions themselves, for these
enlargements belong exclusively to the inferior
or sensitive fasciculi, and the superior or motor
fasciculi pass over their dorsal surface without
penetrating their substance at all.

Before going on to the study of those organs
the object of which is the application, if we
may be allowed the expression, of the nervous
system to the perception of the existence of
outward objects, and of those in which the
reaction designated volition is immediately
effected, that is to say, the organs of the senses
and the muscles, it may be as well to saya
word upon the general functions of the nervous
system itself in its different parts. The
experiments made by M. Audouin and me,
with a view to solve the principal problems
which may be proposed on this subject, have
confirmed the inductions to which we had been
led by views arrived at a priori wholly from
anatomical researches, of which the preceding
may be regarded as the summary. Thus :—

* On the Nervous System of the Sphinx ligustri,
ee G. Newport, Philos. Transact. 1834, pt. il.
p- .

767

istly, The nervous is the system which en-
tirely presides over the sensations and motions.

2dly, The nervous cords are merely the
organs of transmission of the sensations and
of volition, and it is in the ganglions that the
power of perceiving the former and of pro-
ducing the latter resides. Every organ sepa-
rated from its nervous centre speedily loses all
motion and sensation,

3dly, The whole of the ganglions have
analogous properties : the faculty of determin-
ing motions and of receiving sensations exists in
each of these organs; and the action of each
is by so much the more independent as its
development is more isolated. When the
ganglionic chain is nearly uniform through its
whole length, it may be divided without the
action of the apparatus being destroyed in
either portion thus isolated,—always under-
stood, that both are of considerable size;
because when a very small portion only is
isolated from the rest of the system, this
appears too weak, as it were, to continue its
functions, so that sensibility and contractility
are alike speedily lost. But when one portion
of the ganglionic chain has attained a develop-
ment very superior to that of the rest, its
action becomes essential to the integrity of the
functions of the whole.

It must not be imagined, however, from
this that sensibility and the faculty of exciting
muscular contractions are ever completely con-
centrated in the cephalic ganglions, and it
seems to us calculated to convey a very
imaccurate idea of the nature and functions of
these ganglions to speak of them under the
name of brain, as the generality of writers have
been Jed to do, seduced by certain inconclu-
sive analogies in point of form and position.

It is nevertheless to be remarked that in these
animals an obscure tendency to the centra-
lization of the nervous functions is observable
in the anterior portion of the ganglionic chain ;
because if in the Lobster, for instance, it be
divided into two portions, as nearly equal as
possible, by severing the cords of communica-
tion between the ganglions belonging to the
first and second thoracic rings, sensibility, and
especially mobility, are much more quickly
lost in the posterior than in the anterior half;
and this disproportion is by so much the more
manifest as the division is performed more
posteriorly; still there is a great interval
between this first indication and the concen-
tration of the faculties of perception and of
will in a single organ—the brain, of which
every other portion of the nervous system then
becomes a mere dependency.

B.. Organs of the senses.—Do the five
senses exist, and to what degree of development
have they attained in the Crustacea? Such
is the question we have now to consider, and
which we shall sometimes find ourselves in a
condition to answer from the simple inspection
of the various organs of special application.

Thus we discover almost at once that the
sense of general touch is obtuse, and can
convey to the animal no other but confused

768

notions of the existence and of the resistance
of the bodies with which it finds itself in
immediate relationship by its external surface.
To be satisfied of this, it is enough to consider
for a moment the hard and unyielding nature
of the general tegumentary envelope over every
point of the body except the articulations,—
parts which on other grounds are obviously
inadequate to exercise any sense whatever.

Nevertheless, in front of the head there are
certain special organs which all the observa-
tions I have had an opportunity of making
upon the organization of these animals lead
me to regard as parts more particularly destined
to be the seat of the sense of touch. These
organs are the antenne,—those slender fila-
ments, possessed of a great degree of flexibility,
of motility, and of sensibility. M.de Blain-
ville was led to regard these organs as the
seat of the sense of smell; but direct and
conclusive experiment has satisfied us that the
destruction of the antenne has no influence
whatever on the exercise of the sense of
smell: and we are on the same grounds’ in-
duced to believe them destined to the exer-
cise of the sense of touch of considerable
delicacy, unless we would imagine them as
the instruments of some quite peculiar
sense the existence of which would be purely
hypothetical.

The number and disposition of these organs
varies extremely. Some of the Crustaceans
at the very bottom of the series are wholly
without antenne, or are furnished with them
in a merely rudimentary state. Some species
have no more than a single pair; the normal
number, however, is two pairs. In speaking
of the tegumentary skeleton, we have said to
which of the rings these appendages belong ;
we shall only say farther here, that they may
be inserted on the superior or on the inferior
surface of the head according to the respective
development of the different pieces of which
this segment is composed. They do not differ
less widely in their form and composition, and
under this double point of view present modi-
fications analogous to those which we have
specified as occurring in the extremities,

The Crustaceans, like almost all other animals,
make a selection of matters in especial relation-
ship with the state of their organs of nutrition ;
they must therefore be endowed with the
sense of taste. With reference to the seat
of this faculty, which perchance is the mo-
dification of sensibility the least remote from
the sense of touch, it appears to reside in the
Crustacea, as it does obviously in the majority
of animals, in that portion of the tegumen-
tary membrane which lines the interior of
the mouth and csophagus; but the dispo-
sition of the parts there presents no peculiarity
worthy of especial notice.

The Crustaceans perceive the existence of
bodies at a distance by the medium of odorous
particles emitted from these bodies. Many
of the known habits of these animals, and the
certainty with which they are attracted by
baits placed in close traps from which the

CRUSTACEA.

light is exeluded, do not allow us to entertain:
any doubts upon this point; but we are reduced
to conjecture when we are required to point
out the precise seat of the organ of smell.

The horny appendages named antenna are
certainly not it, as M. de Blainville imagined ;*
and the opinion of M. Rosenthal,+ who ascribes
the function to a cavity which he discovered

at the base of the first pair of antenne, requires
to be supported by direct experiment. |

Hearing, at least in a great number of
species, resides in a particular apparatus per-
fectly well known. It (fig. 396)
is found in the inferior surface
of the head, behind the an-
tenne of the second pair, or
upon the first basilar articu-
lation of these antenne them-
selvest (fig. 396, a). It con-
sists in the River-crab of a small:
bony tubercle pierced at its
summit by a circular opening, uyfon which is
stretched a thin elastic membrane, which
Scarpa has compared to that of the tym-
panum, or of the fenestra ovalis of the ves-
tibule in the higher animals. Behind this
membrane there is a membranous vesicle
filled with fluid, into which a branch of the
antennary nerve is observed to plunge. Above
this organ there is another of a glandular
appearance, the intimate relations of which
with the apparatus we have just described
might lead to the belief that it was not un-
connected with the sense of hearing. In the
Palinurus it communicates with an opening
which is pierced through the centre of the -
membrane that closes the auditory tubercle in
front.

The membrane in the greater number of the
Brachyura is replaced by a small moveable os-
seous dise, which in the Maja and some others
presents a pretty broad bony plate ( fig. 397) at

Fig. 397.

6

Auditory dise of the Maja Squinado separated from
the rest of the apparatus, ©

Fig. 396.

its posterior edge, detaching itself at right
angles and running upwards towards the glan-
dular organ already mentioned. Near its
base this lamellar prolongation is pierced ~
with a ‘large oval opening, over which there
is stretched a thin and elastic membrane
which might be named the internal auditory

a Principes d’anatomie comparée, t. i. p. 338 et
+ Reil’s Archiv. und Treviranus’s vermischte —
Schriften, 2ter Band. 2tes Heft. ae

$ Minasi, Dissertazioni di timpanetti del’udito
scoperti nel Granchio paguro. Scarpa, De structura
fenestre rotunde, &c. Anat. observ. 4to. Mutin
1772; Anat. Disq. de Auditu et Olfactu, fol. Ticin,
1789. Cuvier, Lecons d’anatomie comparée, t. ii.
Milne Edwards, Histoire naturelle des Crustacés,

a 1. p- 123, bs o

CRUSTACEA.

membrane, near to which the auditory nerve
appears to terminate. This small bony lamina,
which is moved by minute muscular fasciculi,
recals in some measure the stapes of the
human ear. Under the anterior edge of the
external opening of the ear which is closed
by this bony dise (fig. 398 ), is seen a small

Fig. 398.

Auditory ratus of the Maja in its natural position,
‘showed = removing the carapace and the vis-
cera.

lamina parallel to the internal auditory mem-
brane ; and when the anterior muscle of the
ossiculum contracts so as to bring, in a slight
measure, the whole of this little apparatus
forwards, the membrane of which mention has
just been made rests upon the bony prolonga-
tion, and is made tense in a continually in-
creasing degree; and from the experiments of
M. Savart we know that all increase in the
tension of thin membranes lessens their dispo-
_ sition to be thrown into vibration ;* consequently
in undergoing such a modification, the kind of
tympanum described must serve to moderate
sounds of too great intensity, in their passage
to the acoustic nerve. In other respects it
is evident that the mechanism described pre-
sents the most forcible analogies with what
we observe in the human ear, and that the
ossiculum auditus here stands in lieu of the
chain of small bones which exists in the organ
of hearing arrived at its highest point of de-
velopment.

_ The presence of the long rigid stem formed
by the antennz of the second pair, and its
immediate communication with the organ of
hearing cannot, it might have been presumed
@ priori, be unimportant as regards the per-
ception of sound; and this is found to be the
case in fact ;+ for from the beautiful experiments
of M. Savart we learn that the addition of a
rigid stem is sufficient to render certain vibra-
tions perceptible, which, without this kind of
conductor, are altogether inappreciable.

The auditory apparatus of the Crustacea eon-
‘Sequently consists. essentially of a cavity full
of fluid, to which a nerve adapted to perceive
sonorous impulses is distributed; which ele-
mentary and essential apparatus is assisted in

* Recherches sur les usages de la membrane du
tympan et de l’oreille externe, Journal de Physio-
logie de Magendie, t. iv.

+ Strauss - Driickheim, Considerations générales
sur l’anatomie des Crustacés, p. 419.

769

its functions by certain special organs, such as
elastic membranes and rigid stems, calculated
by their nature to vibrate under the action of
sonorous undulations.

We have still to speak of the organ of sight.
With the exception of certain parasitic species,
the faculty of perceiving the existence of ex-
ternal objects by the medium of light is pos-
sessed by the whole class of Crustacea, and is
found dependent on a particular organ of a con-
siderably complicated structure situated in the
head, towards its anterior aspect, superiorly
or on the sides. Even the exception which
has been made is merely accidental, as it were ;
for in the earliest periods of their existence
the parasitic Crustacea also possess eyes, and
it is only as an effect of the kind of meta-
morphosis which these animals experience that
the organs of vision disappear.

The eyes in insects are simple or compound ;
but this division is inadequate to give us any
proper idea of the various forms under which
these organs present themselves to our observa-
tion in the Crustacea, and into the study of
which we shall, therefore, enter with some
attention to detail.*

The least complex form under which the
eyes of the Crustacea occur is that which has
been designated under the name of Stemmata,
smooth eyes or simple eyes. The structure of
these does not differ essentially from that ob-
served among the higher animals. We distin-
guish, in the first place, a transparent cornea,
smooth and rounded, which is in fact nothing
more than the general tegumentary mem-
brane modified in a particular point. The
internal aspect of this cornea is in immediate
contact with a crystalline lens, generally of a
spherical form ; this, again, is in contact poste-
niorly with a gelatinous mass analogous to the
vitreous humour, and this mass in its turn is
in contact with the extremity of the optic
nerve. <A layer of pigmentum thick and
of a very deep colour, envelopes the
whole of these parts, lining the internal wall
of the globe of the eye up to tke point at
which the cornea begins to be formed by the
thinning of the tegumentary envelope become
transparent. This is what we observe in a
limited number of the Crustacea, among which
we may mention the Limuli, the Cyame, and
the Apus. The number of these simple eyes
never exceeds two or three.

A step in the complexity of the organ of
sight is presented to us in the eyes of the
Nebalia, Branchipus, and Daphnia. In these,
behind the cornea, which externally presents
no trace of divisions, a variable number of
small crystalline lenses and vitreous humours
are found, each included in a kind of sac or
pigmentary cell,~and terminating by coming

* On the structure of the eyes, vide Swammer-
dam, in the Collection Academique, partie étrangére,
t. ve p. 170. Cavolini, Memoria sulla generazione
dei Pesci et Dei Granchi. Strauss, op. cit.
J. Miuiller, Zur vergleichenden Physiologie des
Gesichtsinnes etc. Ann. des Sciences Naturelles,
t. 17. Milne Edwards, Hist. Nat. des Crustacés,
t. i. p. 114,

770

immediately into contact with the optic nerve.
These eyes are obviously made up by the con-
junction of several stemmata under a common
cornea. The Apus, besides its pair of simple
eyes, presents another compound pair, behind
and at some distance from these.

The Amphihoé Prevostii and some other
Edriophthalmians present the transition from
the form last described to that of truly com-
pound eyes, having distinct facets. The cornea
in these is formed of two transparent laminz,
the external of which is smooth and without
divisions, whilst the internal is divided into
a variable number of hexagonal facets, each
of which is a distinct cornea, superposed upon
such a conical crystalline lens, as we shall
have occasion immediately to describe when
speaking of compound eyes properly so called,
or eyes with simple facets.

In these the two membranes, external and
internal, the union of which constitutes the
cornea, present simultaneously the division
into facets, each of which forms anteriorly an
ocular compartment proper to it. These facets,
always hexagonal in insects, are of various
forms in the Crustacea: thus in the Astacus
fluviatilis, the Penez, the Galathee, and
the Scyllari, they are square (fig. 399), whilst
the Paguri, the Phyllosoma, the
Squille, the Gebize, the Calli-
anasse, and the Crabs, have them
hexagonal (fig. 400). The crys-
talline that succeeds them imme-
diately is of a conical form, and
is followed by a vitreous humour
. having the appearance of a gelati-
nous filament, adhering by its base
to the optic nerve. Each of the
columns thus formed is, more-
over, lodged within a pigmentary
cell, which likewise covers the
bulb of the optic nerve. But
the most remarkable circumstance is, that
the large cavity within which the whole of
these parallel columns, every one of which
is in itself a perfect eye, are contained, is
closed posteriorly by a membrane, which ap-
pears to be neither more nor less than the
middle tegumentary membrane, pierced for
the passage of the optic nerve; so that the
ocular chamber at large results from the sepa-
ration at a. point of the two external layers
of the general envelope.

Fig. 401.

Longitudinal section of the Eye of the Lobster.

The gelatinous or vitreous elongated pro-
cesses which succeed the conical crystallines
have been looked upon by several anatomists
as ramifications of the optic nerve; but we
do not imagine that they are so in reality.
In the Lobster, for instance, we have even
seen the surface of the bulb isolated from the
masses in question, divided into compartments

CRUSTACEA.

corresponding to those of the cornea itself,
and lined with a layer of pigmentum perfectly
distinct.

The most remarkable modification of facetted
eyes consists in the presence of a kind of sup-
plementary lens, of a circular shape and set
within the cornea in front of each proper
talline lens (fig. 402). These small lenticular
bodies exist independently, and
are perfectly distinct from the
small corneal facets. In some
cases they might be mistaken
(in the Idotee, for example,
where they may be perceived
singly, and with their distinct
circular forms), and the incau-
tious observer led to conclude that the cor-
neal facets are merely these lenticular bodies
so much enlarged that their hexagonal or
square forms result from their agglomeration
in a point; but there are Crustacea, such as
the Callianassz, in which these two elements
of the external cornea may be perfectly dis-
tinguished, the lenticular body being of insig-
nificant dimensions and occupying the centre
of the corneal facet only (fig. 402). In general,
however, the diameter of the lenticular body
is equal to that of the corneal facet itself, so
that their edges blend. Farther, the lenticular
bodies are most commonly evolved in the sub-
stance of the cornea; but there are cases in
which, under favourable circumstances, they
may be detached from it.

Although the existence of these different
modifications must not be understood as being
exclusive, inasmuch as there are certain Crus-
tacea which exhibit more than one of them at
the same time, for instance, stemmata and
compound eyes, the latter only are the species
of visual organ encountered in the great ma-
jority of cases. Their general number is two ;
but these are occasionally united, so as to
form a single mass, and make the animal
appear at first sight as if it had but a single
eye. This peculiarity of organization can even
be followed in the Daphniz, in the embryo
of which the eyes are first seen isolated; with
the progress of the development, however,
they are observed gradually to approach each
other, and finally to become united. Stemmata
are always immoveable and sessile; the com-
pound eyes with smooth cornez, however,
although in the majority of cases they present
the same disposition, now and then occur
moveable; sometimes they are supported by a
pedicle, moveable in like manner, and pro-
vided with special muscles. The eyes with

Fig. 402.

modifications, and even
supply important charac-

and _ sessile, WE (
eca

whilst in the

i a a i ii i a ek

facets present the same —

ters in classifying these —

animals: thus in the
Edriophthalmia the eyes
are always i

eae

i |
Bi
-
.
:

_ the cephalic

CRUSTACEA. 771

stems of very various lengths, and which every
consideration leads us to view as the limbs or
appendages of the first cephalic ring. It some-
times even happens (fig. 404) that in these
animals, between the outer edge of the cara-
pace and the base of the antenne, there occurs
a furrow or cavity within which the eyes may
be withdrawn or laid flat, so as to be out of
the way of injury; this groove or cavity is
eeeety spoken of under the name of the
orbit.

§ 3. Apparatus of Nutrition.

- In the study of this apparatus we shall have
to consider successively the organs of digestion,
of circulation, of respiration, and of secretion.

A. Apparatus of digestion.— The organs
concerned in the digestion of the food among
the Crustacea may be divided into three
orders, according to the functions they fulfil,
to wit, ist, the apparatus for the prehension
and mastication of the food; 2nd, the alimen-
tary canal; 3rd, the various secreting organs
associated with the intestine.

The Crustacea are divided into two grand
sections in conformity with their habits and
the nature of their food:—the masticators,
which generally live apart from their prey,
pursue it, and seize it in proportion as they
are admonished by their wants or appetite to
do so; and the suckers, considerably fewer in
number, and which in their state of perfect
growth live almost invariably attached to their
prey without executing any other motions than
such as are performed by the latter.

The masticating Crustacea being the highest
in point of organization, we shall commence
our description with them,* and we shall even
select for our particular consideration the spe-
cies among these which have the class of
organs about to be investigated of the most
complex structure, namely, the Decapoda
brachyura. In these animals the mouth is
constantly situated on the inferior surface of
rtion of the body. Two lips
close it anteriorly and posteriorly ; the upper
lip or labrum (a, fig. 405) is a median piece in
the form of a simple fold, and the lower lip
or languette (c) is for the most part bifid. Be-
tween these two pieces and on their sides are
the mandibles, (fig. 406,) appendices of the
fourth cephalic ring, modified so as to serve for
mastication. As in the whole tribe of articu-

* On this subject consult Sevigny Mémoires sur
les Animaux sans Vertébres, Ire fascicule; La-
treille, Hist. Nat. des Crustacés et Insectes, &c. ;
Cuvier, Régne Animal ; Desmarest, Considérations
sur les Crustacés; Milne Edwards, Hist. Nat. des
Crustacés, t. i, p. 61.

Masticatory Organs of the Phyllosoma.

a, upper lip; 6b, mandibles; c, lower lip;
d, maxillez.

lated animals, these organs act laterally, and not
upwards and downwards in the line of the axis
of the body as in the vertebrate series univer-
sally. They do not vary
much in point of form
among the Decapoda;
m almost every one of
these they are seen pos-
sessed of a principal
part terminated by a
cutting edge, or a sur-
face adapted for tritu-
ration; and an appendage which appears to
fasten the food and keep it steady during
the process of mastication. The mandible
itself, which is of extreme hardness, appears
to be neither more nor less than the basilar
piece of the member or appendage, of great
strength and toothed. The articulated pulp
which it supports, in this mode of viewing
the structure, would turn out to be a mere
continuation of the stem (tige), and not a
ibe palp, as its name seems to imply,

ut which it has only acquired from its resem-
blance to the appendage to which the term of
right belongs.

Such is the structure of the mouth among
a certain number of the inferior Crustacea; but
among those to which we now turn our atten-
tion, we remark an addition of as many as five
pairs of modified appendages situated behind
the under lip, and all subservient to the pre-
hension and the mastication of the food. The
two first (figs. 406 and 407) are the most con-
stant; and even when we get low in the series,
and they have lost their special functions, they
can still be traced, although of course only in
a rudimentary state. When well developed
they are without palps and are designated
by the name of jaws. The three other pairs,
again, soon cease to
appear as part of the
implements of digestion,
in order to show them-
selves among the instru-
ments of locomotion;
sometimes, however,
they seem to serve for
both kinds of function,
a circumstance which has

Fig. 407.

wll Wy

772

led to their ordinary denomination of mazil-
lary limbs or feet Cha

Fig. 408.

. 408, 409, 410.)

The forms and dimensions of
these organs vary considerably,
and are obviously in harmony
with their uses; they are by so
much the shorter and flatter as
they are more peculiarly appor-
tioned to the oral apparatus, a
disposition which is nowhere
more conspicuously displayed
than among the short-tailed De-
capods, in which they resemble
horny lamine, armed with teeth
or serre of various sizes, and
supporting an articulated palp (d,
Jig. 408) as wellas a flabelliform
or whip-shaped appendage (c),
which penetrates into the interior
of the branchial cavity. The last
pair of all (fig. 410) presents

a, carapace ;

itself under the
shape of two thin
and much expand-
ed lamine which
serve as a kind of
broad operculum to
cover the whole of
; the oral apparatus.
Starting from this complication of structure,
the greatest in the series, we shall see the ap-
paratus degenerating by successive degrees, at
the same time that in any given group its com-
position presents much less of constancy or
regularity. The Sergestes among the Decapods
have one pair of maxillary feet fewer than the
highest number; the Edriophthalmians have
no more than a single pair, whilst in the
Thysanopoda and the generality of the Sto-
mapoda the number of oral appendages

CRUSTACEA.

d, chelifera; e, f, g, h, i,j, legs, the basilar portions of which
surround the mouth and act as mandibles;
m, branchial or lamelliform appendages; mn, mouth.

amounts to three pairs, and in the Phyllo-
soma to two pairs only. = ye eS
To conclude, the Limuli, a group of Crusta-
ceans of the most singular conformation, are at
the bottom of the scale in this respect; for in
them (fig. 411) the anterior ambulatory extre-
mities themselves surround the mouth, and
their basilar articulations perform the office of
aws. 7 i
The organs of which we have just made
‘mention, are, according to the modifications
they undergo, adapted in a more or less espe-
cial manner to seize, to hold fast, and to
comminute the alimentary matters upon which
the animal lives. Moreover the thoracic ex-
tremities in many species are themselves calcu-
lated to accomplish one or all of these offices
with various degrees of success, according to
their form, their extent, and the mode in which

Fig. 411.

Limulus polyphemus, (ventral aspect. )

b, frontal portion of the carapace; c, thorax ;

1, under-lip ;

they are terminated. The most favourable
disposition to these ends is observed in the
lobsters, crabs, &c.; in a word in a very great
number both of the short and long-tailed De-
capods, in which the anterior thoracie extre-
mities terminate in pincers of greater or less
strength, armed with teeth and sharp hooks
which give them increased powers of pre-
hension. This form results mainly from the
state of extreme development in which the pe- —
nultimate articulation frequently occurs, and —
its assumption of the shape of a finger, by the —
prolongation of one of its inferior angles. —
Against the finger-like process thus produced,
which is of great strength and quite immove- —
able, the last articulation can be brought to
bear with immense force, as it is put into mo-
tion by a muscular mass of great size, and in
relation with the extraordinary size of the pe-

CRUSTACEA.
Fig. 414.

Fig. 412.

Fig. 413.

\

Fig. 412, Ventral aspect of the cephalo-thoracic portion of the
? i

chelestion.
a, trunk or sucker; 6, maxille.

Fig. 413, The trunk or sucker magnified.
a, the labrum; b, the mandibles.

Fig. 414 & 415, The maville.

nultimate articulation (the claws, pincers, or
_ cheliferous extremities ).

e extremity occasionally terminates in two
articulations presenting no kind of unusual
development, but the last of which, termi-
nated by a sharp point and armed with teeth
or serre, returns upon the preceding one, so
as to form a kind of hook or pincer, opening
in the opposite direction, (the sub-cheliform
extremities of the Squille and Creveitine ).
Lastly, these extremities frequently terminate
in a simple acute angle of which the animal
can make no use save in locomotion.

In the Sucking Crustacea, which live parasi-
tically on other animals and feed by sucking
their blood, the structure of the oral apparatus
is extremely different.* Certain pieces which
must be considered as analogous to the /abium
and languette, are elongated, so as to forma
trunk or cylindrical tube, of variable length,
adapted for sucking, and in the interior of
which are lodged the mandibles, now pro-
longed so much that they form two slender
and pointed processes the extremities of which
serve as a lancet. The appendages which in
the masticating Crustacea constitute the jaws,
here continue rudimentary, and the three pairs
of limbs which in the Decapoda complete the
oral apparatus, under the name of maxillary
extremities, are here transformed into organs
of prehension, of different forms, by means
of which the parasite attaches itself to its

victim.

_ In the whole of the Crustacea. the intestinal
canal presents two openings, the mouth and

* See our “‘ Recherches sur l’Organization de
la Bouche des Crustacés Suceurs,” Ann. des Sc.
Nat. t. 28; Burmeister’s Beschreibung einiger
neuen schmarotzer Krebse, in the Acta Acad,
Ces. Leop. Nat. Cur, vol. xvii. p. 1.

773

Fig. 415. the anus, always separated
from each other by the whole
length of the body.

The mouth is the mere an-
terior and outward expansion
of the csophagus; it is fur-
nished with nothing that can
properly be compared to a
tongue; the horny and la-
mellar organ which writers
have sometimes spoken of
under this name is nothing
more than the lower lip,
: which has already been de-

scribed.
The csophagus itself is
short ;-it rises vertically and
. Tuns to terminate directly in
the stomach. Its general
Structure, as well as that of
the stomach and whole of
the intestinal canal, bears a
very close resemblance to
what we observe among the
superior animals. They each
consist of two membranous
layers separated by one of
muscular fibres, always of
greatest thickness in those points in which the
most energetic contractions take place, and
especially at the entrance into and passage
out of the stomach.

The stomach is of a globular form, and of
very great capacity; it fills a considerable
extent of the cephalic cavity, and presents two
portions very distinct from one another; the
cardiac region, vertically surmounting the
mouth and cesuphagus, the axis of which is
lost in its own; and the pyloric region, situ-
ated behind the former, and forming a right
angle with it.

But the most remarkable feature presented
by the stomach of the Crustaceans is the very
complex masticatory apparatus it contains.
This consists of a considerable number of
pieces, the form and disposition of which vary,
and are always singularly in harmony with the
kind of food taken and the general habits of
these animals. The apparatus, as well from
the important office it fulfils, as from its
being no where else encountered in so perfect
a state of development, were worthy of a
description which would swell this article to
too large a size; we shall therefore be brief,
and merely state generally that it consists of a
great number of pieces, so connected as to
constitute a kind of solid frame armed in-
ternally with tubercles or sharper teeth situated
around the pylorus, and capable of being
moved so as to bruise or tear in pieces the
alimentary matters subjected to their action,
and as they are about to pass through this
opening.*

The different pieces composing this appa-
ratus vary considerably in the different genera,

* Vide Cuvier, Legons d’Anatomie Comparée,
t. iv. p. 126, and Milne Edwards, Hist. Nat. des
Crustacés, t. i. p. 67, for further details.

774

Digestive canal of the Maja.

a, Cardiac portion of the stomach.

6, b, Upper portion of the frame-work of the
stomach.

e, Pyloric portion of the stomach,

d The small intestine.

e, Termination of the biliary ducts.

f, Anterior appendages of the intestine.

g, Posterior appendages.

h, Rectum,

and even in the several species of the same
genus. Still every one of them may be de-
monstrated with a little care, in the whole of
the Brachyura and of the Macroura. They
are less numerous, and are singularly modified
in proportion as we recede from these types.
In the Squilla mere vestiges only of the ap-
paratus are found in two semicorneous pieces
covered with rounded projections; and _ its
functions are performed by a branch of each
mandible aS fyi even to the pyloric
orifice of the stomach.

The intestine extends from the pylorus to
the anus without curve or convolution in its
course ( fig.416,d,h). In the superior Crustacea

CRUSTACEA.

Fig. 417.

<<

\:
RS Ab
AL | ym
i Ups
f wy
Y

Liver of the Lobster.

a, stomach; b, intestine; c, left lobe of the liver
in its natural state; d, right lobe dissected, so
as to show its structure and the disposition of the
biliary ducts.

it may be distinguished into two portions, one of
which may be named the duodenum, the other
the rectum. 'These two portions where they
occur vary extremely both in their nature and
in their relative lengths. Sometimes they are
separated by a valve (Lobster) corresponding
internally to a cireular external elevation; but —

still more frequently their respective limits are
not obviously marked, and among the whole —
of the inferior members of the family the —
intestinal canal is entirely cylindrical, and per- _
fectly identical in its constitution through its
whole length. The anus is constantly seated
in the last ring, and is closed by certain mus:

cular fibres which perform the office of a
sphincter. ; ae

14
bi
a
A's
:
F
| :
4

CRUSTACEA.

The biliary apparatus of the Crustacea is of
very large size in the Decapoda. The liver is
symmetrical (fig.417), and consists of two
halves generally separate one from another,
and the whole organ is made up of an agglo-
meration of cecums, which by one of their
extremities empty themselves into excretory
ducts. These by their union form larger and
larger trunks, and the secreted fluid or bile is
finally poured by a double channel into the
a portion of the stomach. The liver is

und to undergo extensive modifications as it
is examined in individuals lower and lower in
the series; in the Edriophthalmians, finally,
we discover nothing except three pairs of bili-
ary vessels analogous to those of insects.

The liver is not the only secerning organ
whose product is poured into the intestine.
On each side of the pyloric portion of the
stomach, we observe two blind tubular cavi-
ties narrow and much elongated in their form,
which pour out a whitish fluid (fig. 416, f, f);
and at the point of conjunction of the two por-
tions of which the intestine frequently consists,
as has been said, there is a third tubular cavity
or vessel in all respects similar to these two
(fs. 416, g). These tubuli are all wanting in

e Astacus fluviatilis, and in the Astacus ma-
rinus the single posterior tubulus is the only
one found. Nothing positive is known with
regard to the uses of the fluid secreted in these
tubuli.

To conclude, there are two organs of a green
colour situated on either side of the cesopha-
gus, the structure of which is glandular, and
which appear to bear some analogy to the sali-
vary glands.

B. Of the blood and circulation —We are

Fig.

775

altogether without positive information as to
the mode in which the nutritious fluid, elabo-
rated by the process of digestion, passes from
the intestinal canal into the torrent of the cir-
culation. Hitherto no chyliferous vessels have
been detected, and we are therefore led to
believe that it is by imbibition that the trans-
ference takes place from the intestine to the
bloodvessels in the Crustacea.

The blood of the Crustacea is a colourless,
or slightly bluish coloured fluid, holding an
abundance of circular-shaped globules in sus-
pension. It is extremely coagulable. Its che-
mical composition has not been investigated.

This nutritious fluid is put into motion by a
heart, and circulates through a vascular system
of great complexness. Willis,* Swammer-
dam,+ Cuvier,{ Desmarest,§ and several others
have given a description of this system; but
there are still innumerable points upon which
Opinions remain different. The following are
the conclusions to which M. Audouin and
I have come from a careful study as well of
the anatomical disposition of the circulatory
apparatus of the Crustacea, as of the progress
of the blood through its interior.||

The circulation of the blood in these ani-
mals is accomplished in a manner very similar
to what takes place in the Mollusca. The
blood pushed forward by the heart is distri-
buted to every part of the body, from whence
it is returned into large sinuses situated at no
great distance from the base of the branchiz ;
from these sinuses it is sent on to the respi-
ratory apparatus which it traverses, and from
which it then finds its way to the heart, to
recommence the same circle anew. The heart
is consequently aortic and single.

418.

Viscera of the Cancer Pagurus, ‘
Ff, heart; a, ophthalmic artery; 0, abdominal artery; c, stomach; @é, skin;
g, branchie, inverted to show the efferent vessels; h, vault of the flancs ;
n, branchiz in their natural position ; m, flabellum; /, liver; 2, testicles.

* De anima brutorum, caput tertium, p. 16.

+ Collect. academique, partie étrangére, t. v.
p- 126.

¢ Legons d’Anatomie Comparée, t. iv. p. 407, et
Régne Animal, lre ed, t. ii. p. 512, et t. iii. p. 5.

Considerations sur les Crustacés, p. 57.

Recherches anatomiques et physiologiques sur
la Circulation dans les Crustacés, Ann. des Sc. ~
Nat. t. ll.

776

The heart is always found in the median
line of the body, and lying over the alimen-
tary canal near the dorsal aspect. Its form is
various ; in the Decapods it is nearly square,
and lies in the middle and superior part of the
thorax, being separated from the carapace by
tegumentary membranes only, and may be
seen in the space included between the two
vaults of the flancs. In structure it appears
to be composed by the interlacement of nu-
merous muscular fibres, fixed by their extremi-
ties to neighbouring parts and passing to some
distance over the aggregate at either end,
so that the whole organ brings to mind such
a figure as would be formed by the super-
position of a number of stars the rays of
which do not correspond. In the other orders
this general form of the heart varies conside-
rably, from the figure of an oblong square of
rather inconsiderable size, as it occurs in the
Decapoda (fig. 418, f), to that of a long cylin-
drical vessel extending through the whole
length of the body as it appears in the Stoma-
poda (fig. 419), and the Edriophthalmians.
In the former of these it gives origin to six
vascular trunks, three of which issue from the
anterior edge, and three from the posterior
surface ; each of the-six openings is closed by
a valvular apparatus which prevents the regur-
gitation of the blood.

The first of the three anterior vessels is
situated in the median line and is distributed
to the eyes, in consequence of which we have
entitled it the ophthalmic artery (a, fig. 418).
Lodged within the substance of the general te-
gumentary membrane, it continues its course
without undergoing any subdivision along the
median line through the whole length of the
thorax, until, arrived opposite the eyes, it sub-
divides and terminates in two branches which
penetrate the ocular peduncles.

On the two sides are the two antennary
arteries. They run obliquely towards the an-
tenne, sending off numerous branches to the
tegumentary membrane in which they are at
first lodged; they then plunge more deeply,
sending branches to the stomach and its mus-
cles and to the organs of generation, between
which they insinuate themselves by following
the folds of the same membrane which parts
them. Lastly, each of these vessels subdivides
into two branches, one of which proceeds to the
internal and the other to the external antenna.

Two hepatic arteries arise from the fore part
of the inferior surface of the heart, and pene-
trate the liver, there to be ramified; but they
are only found double and distinct from one
another so long as the liver is met with divided
into two lobes, as it is in the River-crab and
Lobster.

From the posterior part of the same surface of
the heart there proceeds a large trunk, which,
from its importance, might be compared with
the aorta. is is unquestionably the vessel
which many authors have spoken of as a great
vena cava: we have entitled it the sternal artery.
It bends forwards, giving origin to two abdo-
minal arteries (0, fig. 418), dips into the sternal
canal, distributing branches to the different

CRUSTACEA.

thoracic rings, as also to the five first |
rings, which it passes over in its course. Meet- —
ing with the esophagus it bifurcates, but still
sends branches to the mandibles and the whole
of the anterior and inferior parts of the head. —

The bulb presented by the sternal artery at

its origin, in the Macroura, is the part which

Willis characterized as the auricle of the heart.
As concerns the two abdominal arteries, which
may be distinguishedinto superior and inferior, —
and which arise from the kind of cross which —
it forms almost immediately after its exit, they
are in precise relationship in point of size with
the magnitude and importance of the abdo-
men itself. In the Brachyura they are mere
slender twigs; in the Macroura, on the con-
trary, they are capacious stems, and the inferior
of the two sends branches to the two posterior
pairs of thoracic extremities. . ’

The disposition of the three first vessels is
the same in the Stomapoda as in the preceding
species ; but the great vessel which represents
the heart being extended through the whole
length of the body, supplies immediately other
arterial branches in pairs, and in number equal
to those of the rings.

Arterial system of the Squilla.
b, heart; a, anterior artery.

Fig. 420.

Venous system of the Maja.

a, venous sinuses; 6b, branchie; c, vault. of t
flanes partly taken away; d, legs.

4
:
:
d
:
ny
ia

el ARTE DIB oe

CRUSTACEA. 777

The blood returns from the different parts of
the body by canals, or rather vacuities among
the tissues, (for they have no very evident
appropriate parietes,) which terminate in the
venous sinuses, situated close to the branchiz.

In the short-tailed Decapoda we find no
more than a double series of these sinuses,
included within the cells of the flancs above
the articulations of the extremities. They com-
municate with one another, and they appear to
have no parietes other than laminz of cellular
membrane of extreme tenuity which cever the
neighbouring parts. Each of them, neverthe-
less, receives several venous conduits, and
gives origin at its superior and external part te
a vessel which, traversing the walls of the
flancs at the base of the branchie, conducts
the blood to the latter organs. This is the
external or afferent vessel of the branchiz.

We find the same lateral venous sinuses in
the Macroura; but instead of communicating
with one another athwart the thoracic septa, as
is the case in the Brachyura, they all empty
themselves into.a great median vessel, which
is itself a venous sinus, and occupies the
sternal canal. In the Squilla this sinus is al-
most the only vessel which serves as a reservoir
to the venous blood.

The blood, after having been arterialized in
its passage through the capillaries of the
branchiz, is poured into the efferent vessel,
which, as we shall immediately have occasion
to see when treating of the respiratory process,
runs along the internal surface of each bran-
chia. It enters the thoracic cells in the same
manner as the afferent vessel passed out from
them, bends upwardly under the vault of the
flancs, and thus takes its course towards the
heart. It is to this portion of the canal that
we have given the name of branchio-cardiac
vessel.

The mode in which the blood enters the
heart is still a subject under discussion. Our in-
quiries lead us to believe that this uid, poured
by the branchio-cardiac canals into a sinus
Situated on each side of the heart, penetrates
this organ by means of certain openings situated
in those parts of its substance which are
directly opposite to the canals mentioned.
But Messrs. Lund and Strauss imagine that
the blood is effused as it were into the peri-
¢cardium (which is named auricle by the latter
anatomist) to penetrate from thence by open-
ings situated on the superior surface of the
heart.* These openings, Boece. we conceive
to be closed in the natural state by means of a
membrane, and it is also worthy of remark
that the writers just cited were unacquainted
with the lateral openings which establish a
much more direct communication with the
interior of the organ. We must also add that
the celebrated John Hunter, whose labours
upon this subject have hitherto remained un-
known to the world, but which have very re-
cently been given to the public by Mr. Owen,

- * Lund, Doutes sur l’existence du systeme circu-
latoire dans les crustacés, Isis 1825. auss, Anat.
comp. des Animaux articulés.

VOL. I.

had long ago ascertained the existence of the
venous sinuses and of the lateral openings of
the heart, although he seems to have thought
that the circulation was not complete in the
manner we have described it.*

In the most inferior groups of the class of
Crustaceans the apparatus of the circulation
becomes much less perfect, and even seems to
disappear entirely in the last of the Haustel-
late tribes. In the Argula, for instance, there
still exists a heart, but the arteries as well as the
veins appear to be nothing more than simple
lacune, formed in the interstices between the
different organs; and in the Nicothoa, &c. no
distinct trace of any portion of a circulatory
system has yet been discovered.

C. Of the respiration —The Crustacea, like
all the other tribes especially formed for living
under water, respire by means of certain parts
of their external covering modified in its struc-
ture in order to fit it for this function, and
known under the name of branchie. This
character is even so completely inherent in the
organic type proper to this class, that it is still
ae pee" in certain species which live on the
and and not in the water.

Nothing, however, can be conceived more
various than the form and disposition of the
organs of the branchial respiration among
these animals: in some the function is per-
formed by an extremely complex apparatus,
consisting in great part of organs created ex-
pressly for this end; in others it is delegated
to certain appendages which do not exist for
the office exclusively, but are rather turned
from their more ordinary and obvious uses to
subserve this important function. In others
still, we neither discover special organs of
respiration nor other parts whose structure fits
them evidently to supply the place of branchiz;
in these cases we can only suppose that the
oxygen held in solution by the water acts upon
the nutritious fluid of the animal by the inter-
medium of the entire tegumentary covering.

Let us first review the respiratory apparatus
in its state of greatest complexity, but com-
mencing with it in the embryo and following
it in its progressive development, in order that
we may be the better prepared to compare it
with those forms which will be presented to us
among species less elevated in the series of the
Crustaceans.

In the earliest periods of embryotic life of the
common Astacus fluviatilis, we discover no trace
of branchiz ; but at a somewhat more advanced
stage of the incubation, though still before the
formation of the heart, these organs begin to
appear. They are at first small lamellar appen-
dices of extreme simplicity, attached above the
three pairs of maxillary extremities, and repre-
senting the flabelliform portions of these limbs.
Soon these lamellar appendages elongate and
divide into two halves, one internal, lamel-
lar and triangular, the other external, small
and cylindrical; lastly, upon the surface of

* Catalogue of the Physiological Series of Com-
parative Anatomy, contained in the Museum of
the Royal College of Surgeons, vol. -

E

778

this, strize are observed to appear, which are
the rudiments of the branchial filaments.
During this interval the thoracic extremities
have become developed, and above their bases
other branchie have made their appearance,
presenting in the beginning the form of tuber-
cles, and subsequently that of stilets; smooth
and rounded on their surface, but by-and-by
becoming covered with a multitude of small
tuberculations, which by their elongation are
gradually converted into branchial filaments
similar to the preceding. During this period
of the development of the branchie these
organs are applied like the extremities to the
inferior surface of the embryo; but they sub-
sequently rise against the lateral parts of the
thorax, become lodged within a cavity situated
under the carapace, and thus are no longer
visible externally.

The cavity destined to protect in this manner
the branchial apparatus, is neither more nor
less than an internal fold of the common tegu-
mentary membrane. It shows itself first under
the guise of a narrow groove or furrow, which
runs along the lateral parts of the thorax below
the edge of the lateral piece of the carapace.
This longitudinal furrow is not long of expand-
ing, and becomes consolidated by its superior
edge with the internal surface of the carapace,
which, by being prolonged inferiorly, consti-
tutes the external wall of a cavity, the opening
of which, situated above the base of the
extremities, becomes more and more contracted,
and ends by being almost entirely closed. The
space in this way circumscribed encloses the
branchie, and constitutes what is called the
respiratory cavity of the Decapod Crustaceans.

From what has just been said, it would ap-
pear that the embryo of the Astacus fluviatilis
presents four principal periods with reference
to the state of the respiratory apparatus; istly,
that which precedes the appearance of this ap-
paratus; 2dly, that during which the branchie
are not distinguishable from the flabelliform ap-
pendages of the extremities, or in which it
consists of simple lamellar or stiliform pro-
cesses, which appear as mere processes of
other organs especially dedicated to locomotion
or to mastication; 3dly, that characterized by
the transformation of these extremely simple
appendages into organs of a complex structure,
entirely distinct from the extremities, but still
entirely external; 4thly and lastly, that during
which the branchize sink inwards and become
lodged in a cavity especially adapted for their
reception, and provided with a_ particular
apparatus destined to renew the water neces-
sary to the maintenance of respiration.

If we now turn to the examination of the
apparatus of respiration in the different groups
in which it exhibits important modifications,
we shall, in the series of Crustaceans, encounter
permanent states analogous to the various
phases through which we have just seen the
apparatus passing in the most elevated animals
of the class.

And, in fact, the first period which we have
particularized above in the embryonic life of the
Decapod is exhibited in the permanent condi-

CRUSTACEA.

‘to take

tion of some inferior Crustaceans, in which not
only is there no special organs for respiration,
but in which none of the appendices occur
with such modifications of structure as would
fit them to become substitutes for the branchie,
in which, consequently, the process of respira-
tion, that is the aeration of the blood, mes Ws

lace over the surface of the body at —
large. The greater number of the Haustellate
Crustacea, of the Entomostraca properly so
called, of the Copepoda, and even of the
Phyllosomata, appear to belong to this type
of organization.

A state analogous to that which characterizes
the second period in the development of the
embryo of the Decapod, is presented to us in
a large number of other Crustaceans, the orga-
nization of which is more perfect than that of
the animals of which mention has just been
made, we mean the Branchiopoda and. Edri-
ophthalmia, in which, although we do not yet
find branchie properly so called, that is to
say, organs peculiarly devoted to respiration,
we discover certain appendages of the extre-
mities which serve for this function. In the
Branchiopoda (fig. 421) the whole of the tho-
racic extremities present
a lamellar conformation,
and the two external
portions of the appen-
dages corresponding to
the palp and flabellum
(fouet ), form membra-
nous vesicles of a flat-
tened form, soft to the
touch, and highly vas-
cular, the structure of
which appears eminently calculated to facilitate
the action of the air upon the nutritious fluid.
(, c, fig. 421).

In the Amphipoda another step appears to
be taken in the elaboration of the respiratory
apparatus. Not only does the function of
respiration tend to become centred in certain
appendages, whose structure is modified for
this end, but this localization, if the term may
be allowed, becomes more complete; for the
two appendicular portions of the thoracic
extremities no longer concur indistinctly and

vicariously in the performance of the function;
the palp (6, fig. 422) has other uses apportioned
to it, and the flabellum (c) alone plays the part
of the branchiz. These appendages, in other re-
spects, do not present any thing peculiar in their

See ie

;
i)
7
1

CRUSTACEA. 779

conformation ; they appear like a vesicular or
foliaceous expansion, of an extremely soft tex-
ture, which is attached to the inner edge of
the base of the thoracic extremities; their
dimensions generally increase from before back-
wards, and the last pair of thoracic extremities
is not furnished with any: their total number
varies from eight to twelve. These organs,
aa a under the thorax, float in the
ambient fluid, and the water in contact with
their surface is incessantly renovated by means
of the motions performed by the abdominal
extremities of the animal, motions which occa-
sion a rapid current from behind forwards
along the ventral aspect of the body.

In the Leemodipoda, the parts which perform
the office of branchie are vesicular bodies
formed by the flabelliform appendage of a
certain number of the pairs of thoracic extre-
mities. In the Isopoda, finally, the locomotory
extremities no longer serve for respiration, the
function being committed to the five first pairs
of abdominal extremities which are entirely
devoted to it and cease to have any other uses.
These extremities, which are designated under
the name of false branchial limbs, consist of a
cylindrical articulation, supporting two folia-
ceous, soft membranous lamine, vascular in a
greater or less degree; frequently, too, we
perceive on their inner side a small appendage,
which may be regarded as analogous to the
femur or stem of the other extremities, whilst
the two lamine, of which mention has just
been made, appear to represent the palp and
the flabellum. In the greater number of Iso-
poda these organs are completely exterior, but
in several (such as the Idotea) the last ring

Fig. 423.

Fig. 424.

Respiratory apparatus of the Idotea.

of the abdomen supplies them with a cavity,
the entrance to which is closed by valves
which constitute the two appendages of the
same ring.

The Stomapoda which have already supplied
us with an instance of the absence of deter-
minate organs of respiration, also exhibit
something analogous to the transition state of
this apparatus during the second period of the
embryonic life of the Decapod. In the genus
Cynthia the branchie are represented by a
small membranous cylinder, attached by its
middle to a peduncle, itself implanted upon
the extremity of the basilar articulation of the
five first pairs of abdominal extremities.

The third type of the respiratory apparatus
specified above, is presented to us by other

Stomapods, known under the names of Squille
and 'Thysanopodz. In these creatures, in fact,

we discover branchie properly so called, the
structure of which is greatly complicated,
more so even than in the Crustaceans at the
very head of the series; still the respiratory
apparatus asa whole is much less complete,
for they are not included in a cavity, and float
freely in the water which bathes the entire sur-
face of the body of the animal. In the Squille
(fig.425) the branchiz are attached to the basilar
joint of the first five pairs of abdominal extremi-

Fig. 425.
NTN
2 \ i \?
One of the branchie
of the Squilla. a,
branchia fixed to the

abdominal extremity

(6).

ties, and each consists of a long cylindrical
tube, upon one of the sides of which proceeds
a series of small tubes disposed parallel to one
another like the pipes of an organ and. support-
ing in their turn a series of long cylindrical and
very numerous tubes.* In the Thysanopoda
the branchiz also resemble plumes, but in-
stead of being situated on the abdomen, they
are attached to the thoracic extremities.+

Finally, the last or highest term of develop-
ment which we have mentioned in the River-
crab, is also presented to us by the entire order
of Decapod Crustaceans. Not only is the func-
tion of respiration thrown upon particular
organs, created expressly for this purpose, in
the whole of these animals, but further, the
organs themselves are lodged and_ protected
within especial cavities, and the renewal of the
water necessary to their functions is secured by
the action of distinct appendages belonging
more particularly to the masticatory and loco-
motory apparatuses.

Let us now take a survey of the branchial
cavity. It occupies (fig. 426) the lateral part
of the thorax, and extends between the vault of
the flancs and the lateral portion of the cara-
pace, from the base of the extremities all the
way towards the dorsal aspect of the animal.
As we have already said, it is formed by an in-
ternal fold of the common tegumentary mem-
brane, which, after having formed the vault of
the flancs, re-descends towards the base of the
extremities to become continuous with the
carapace. The internal and inferior wall of
this cavity is consequently formed by the vault
of the flancs itself, and its external and superior
wall by a membranous septum, which in the
greater part of its extent is for the most part
connected with the corresponding portion of

* Cuvier, Lecons d’Anat. comp. t.iv.

+ Mém. sur une disposition particuliére de l’ap-
pareil branchial chez quelques Crustacés, par Milne
Edwards, Ann, des Sciences Nat. tom. xix,

3B 2

780

Branchial cavity of
the Maja Squinado
laid open.

a, branchie; 6, vault of the flancs; ¢, carapace ;
d, efferent duct; e, valve.

the carapace. This last part of the walls of the
branchial cavity presents an epidermic layer of
extreme thinness, but covering a thick and
shaggy membrane, the texture of which is
found to vary, as we shall see by-and-by.

The cavity thus formed communicates ex-
ternally by two passages, the one destined for
the entrance, the other for the exit of the water
necessary to respiration. The disposition of
the efferent opening varies but little; that of
the afferent orifice, on the contrary, presents
great varieties in the different groups of which
the class of Decapods is composed.

The efferent orifice always occupies the ante-
rior extremity of the’ branchial cavity, and is
‘continuous with a canal (d, fig. 426 and_f, fig.
428) the parietes of which are formed su-
periorly by the epimeral pieces of the last ce-
phalic rings, and inferiorly by the pterygo-
stomian portions of the carapace (6, fig. 427).

Head of the Maja Squinado.
a, afferent opening of the branchial cavity; 0b,
carapace; ¢, anterior extremities; d, posterior
maxillipedes.

This canal runs forwards, passes to the out-
side of the oral apparatus, and terminates in

front of the mouth (g,fig. 428). In its interior
there is a large valve, which is falling and rising
continually, as if it moved upon a pivot, and
which in this way occasions a rapid current

CRUSTACEA.

The same parts, the posterior maxillipedes and a por-
tion of the carapace having been removed.

a, afferent opening; d, portion of the posterior
maxillipedes ; e, commencement of the efferent
canal (f) g, the termination of the efferent
eanal; A, the valve.

from behind forwards in the water with which
the cavity is filled. This valvular apparatus is ;
neither more nor less than the flabelliform
appendage of the second pair of maxillipedes
which acquire dimensions in relation with the
importance of the new function they have here
to perform (h, fig. 428).

In the long-tailed Decapoda, and in the
greater number of Anomoura of the same
family, the respiratory cavity is open along ;
the whole extent of its inferior edge; the
carapace is not applied accurately to the
lower margin of the vault of the flanc, and
itis by the empty space thus left above the
base of all the extremities that the water makes
its way to the branchize. In the Brachyura
the afferent orifice of the branchial cavity is
more circumscribed, but varies in a still greater
degree. In nearly all the Crustacea it exists
almost immediately in front of the base of the
first pair of ambulatory extremities, and con-
sists of a kind of cleft, of considerable breadth,
which in this place occurs between the edge of
the carapace and the thorax (a, fig. 427), and
which is occupied by a prolongation of the ba-
silar joint of the external maxillary limb (d),
disposed in such a manner as to close it com-
pletely or to open it at the desire of the ani-
mal. In the genus Dorippus a slight variety
in the disposition of this opening is ob-
served; here at first view it appears to be
pierced directly in the pterygostomian portion
of the carapace; but it is in reality formed
by an empty space left between the edge of
the dorsal shield and the base of the external
maxillary limb; only here, this space, in-
stead of presenting itself immediately in front
of the base of the anterior extremities, is se-
parated from this by a prolongation of the —
carapace. In the genus Ranina the carapace
is jomed to the thorax above the whole of —

these limbs, so as to leave no opening in this —
situation for the passage of the water, and it
is at the origin of the abdomen that the affe
opening of the branchial cavity occurs. La
in the Leucosia, this cavity is in like manner
completely closed above the base of the extre-
mities, and it is by a conduit parallel to the
efferent canal, and opening outwardly likewise

CRUSTACEA.

in front of the mouth, that the water reaches
the interior of the branchial cavity.

The same, without the external or posterior max-

illipedes,

The branchie contained in the two cavities,
one on either side, whose conformation we have
now described, are disposed along the vaults of
the flancs. They are shaped like a quadran-
gular pyramid, the base being fixed by means
of a peduncle to the inferior part of this vault
or to the membrane which extends from its in-
ferior edge to the basilar articulation of the
corresponding limb; some of them are even
inserted into this articulation. Each of these
organs consists of two large longitudinal vessels
situated on the opposite
edges of a_ transverse
septum, which extends
from the base to the
apex of the branchia, and
presents on each side
a great number of lamel-
lar or cylindrical pro-
longations. Of these
two principal vessels
the external is the affe-
rent one, of which men-
tion has already been
made in treating of the
circulation and its organs; the internal again is
the efferent vessel; the capillaries by which
these two communicate run in the substance of
the branchial lamellez, situated on either side
of the median septum.

In the whole of the Decapoda brachyura and
anomoura, and in the greater number of the ma-
croura, the folds of the tegumentary membrane
which constitutes each branchia, are in the
form of very thin lamelle, directed perpendi-
cularly to the axis of the pyramid, and lying
one over another like the leaves of a book.
But in Crawfish, the Lobster, the Nethrops,
the Palinuri, the Scyllari, and the Gebiz,
these lamelle are replaced by a multitude of
small cylinders, attached by their base, and
closely packed side by side, like the bristles of
a brush.

The number of branchial pyramids varies

are arranged under the base of the precedin
and attached to the basilar articulation of the
second and third pairs of maxillary extremi-
ties.
the branchiz are often found arranged in several
ranks, and generally occur on the two last
thoracic segments, as well as upon those that
precede these (ji,

781

greatly, especially in the Macroura; at the-
most it 1s twenty-two, as is the case in the

Astacus and the most nearly allied species;

in other macroura the number is eighteen, as in

the Palinuri, Scyllari, Penez ; fifteen, as in

the Gebiz ; twelve, as in the Pandalus; ten, as

in the Calianassz ; eight, as in the Palemons;

and even seven only, as in the Crangons, Hip-

politi, Sergestes, &c. In the Anomoura the

number also varies very much. In the Bra-

chyura we can almost always reckon nine

branchie on each side of the body; two of
this number, however, being merely rudiment-
ary; sometimes two or one of these last is

entirely wanting; and there are even species

in which the branchia, which usually occu-

pies the antipenultimate ring of the thorax,

iS missing.

The mode in which these organs are placed
varies in a like degree: in the Brachyura (fig.
426) the whole, with the exception of two rudi-
mentary branchie, are arranged along one and
the same line, and rest parallel to one another
upon the vault of the flancs; the two last rings
of the thorax never support any, and of the two
rings which correspond to the second and third
pairs of extremities, each presents a single py-
ramid attached to a hole pierced in the
epimeral piece near to its inferior edge (fig.384).

he five branchiz, situated in front of these,
are attached above the edge of the vault of
the flancs, and with the exception of the
first are connected two and two upon com-
mon ne Lastly, the two rudimentary
branchie which complete the series anteriorly,

Fig. 431.

3)

In the Anomoura and the Macroura,

Wg. 431).
In the greater number of the Decapoda the

flabelliform appendages of the maxillary or of
the ambulatory extremities penetrate into the
respiratory cavity, and by their motions sweep,
as it were, or stroke the surface of the branchiz.
Some anatomists have even imagined that it was
by their action that the water necessary to respi-
ration was renewed in the interior of the branchial.
cavities ;* but this is a mistake ; these appen-

* Cuvier, Lecons, t. iv. p. 432.

782 CRUSTACEA.

dages have little or no influence upon the cur-
rent which is continually traversing the respi-
ratory antrum, and which is produced by the
motions of the great valvular lamina, already
described as belonging to the second pair of
the maxillipedes, and situated in the efferent
respiratory canal.

The very secondary part which the flabelli-
form appendages of the thoracic extremities
play in the interior of the respiratory cavities,
is of itself a sure indication of the indetermi-
nateness of their numbers and relations to
the branchial pyramids. Thus whilst in the
Lobster and the nearly allied genera, these ap-
pendages, to the number of five on either side,
belong to the four first pairs of ambulatory ex-
tremities and to the third of the maxillary
pairs, and run from below upwards between
the branchial fasciculi, we only find three pairs
in the Brachyura, belonging exclusively to the
maxillary extremities, and penetrating into the
branchial cavities horizontally, two on the outer
surface of the branchie and one between the
inner surface of these organs and the flancs.

We said in beginning this article that the
Crustacea, by their general conformation, were
evidently adapted to a purely aquatic life; this
proposition must only be understood as gene-
rally applicable to the class, because there are
genera which form exceptions to it, in regard to
which we have still a few words to add.

The Telphusiz and some other families
of Crustaceans have the power of emerging
from the water, and of entering it again
after a longer or shorter stay upon dry
land. But this fact is to be explained by the
smallness of the two openings by which each
of the branchial cavities communicates with
the exterior, by which means a very small
amount of evaporation only takes place from
them. The whole of the Crab tribe have, in a
greater or less degree, the faculty of: the par-
ticular species mentioned, provided the air by
which they are surrounded is saturated with
moisture; because if they die asphyxiated
when brought into the air under ordinary cir-
cumstances, it is principally because their bran-
chie having become dry are thereby unfitted to
accomplish their functions.

But there are other species which are re-
markable for the faculty they possess not
only of living habitually out of water, but be-
cause they are infallibly drowned by being
kept long immersed in that fluid—these are
the Gecarcini or land-crabs. Many hypotheses
were broached to afford an explanation of this
phenomenon, when a careful study of the diffe-
rent forms under which the organs of respira-
tion present themselves in these different genera,
Jed us to discover in the membrane which lines
the walls of the respiratory cavities, modifica-
tions analogous to those which are observed
among fishes of the family ofthe Acanthopterygia
pharyngee labyrinthiformes, &c. Sometimes
we found folds and lacune capable of serving
as reservoirs of a certain quantity of water ;
sometimes, as in the Birgus, a spongy mem-
brane equally well calculated to store up the
fluid necessary to keep the organs of respira-

tion in the state of humidity essentially neces-
sary to enable them to perform their functions.
It is well known, too, that the Land-crabs of
which we are now speaking, never remove far
from damp situations. Some naturalists are of
opinion that the tegumentary membrane with
which the branchial cavity is invested, is also
the seat of active respiration; M. Geoffroy St.
Hilaire even goes so far as to regard the growths
with which the surface of this membrane is
covered in the Birgus, as constituting a true
lung.

It would appear, consequently, that it is
owing to the activity of the function of aerial
respiration in the Gecarcini, that these ani-
mals are drowned when plunged under water,
although they be provided with branchiz ;
and it is owing to these organs being kept in
a suitable state of humidity that these creatures
owe, at least in part, their faculty of breathing
air.

We have said above that the principal cause
of the death of our ordinary Crustaceans exposed
to the air is the drying up of their branchiz ;
but this is not the sole cause of the asphyxia
they suffer; it would seem that the collapse of
the branchial lamelle which takes place when
these organs are not supported by the water,
and the greatly diminished extent of surface
thereby exposed to the oxygenated fluid, con-
tributes mainly to prevent aerial respiration
from proving adequate to maintain life among
the common aquatic Crustacea.

With regard to the modifications presented
by the respiratory organs of the Onisci, which
like the Gecarcini live far from water, nothing
certain is yet known. The opinion that the
abdominal false limbs, which serve as respi-
ratory organs among the Isopoda in general, are
here vesicular, and perform the office of lungs
internally, whilst their external surface acts
in the manner of gills, still requires to be
confirmed.

§ 6. Of Generation.

Sexual organs are readily demonstrated in
the whole class of Crustaceans, but those of
the two sexes never exist in the same indivi-
dual. The doubt which at one time pre-
vailed in regard to this fact, and which mainly
arose from no other than females of certain
species having ever been taken, is at once
put an end to by the circumstance of the con-
siderable dissimilarity in their external form,
which occurs between the males and females
of these species; this dissimilarity indeed is,
in some instances, so great that naturalists
were led into the error of regarding the male
and female of the same creature not only as be-
longing to different species, but even to diffe-
rent genera. Oviparous reproduction is also a
constant character of the class. -

Generally speaking, the reproductive appa-
ratus, whether in the male or in the female, is

perfectly distinct, especially at the period when — ;

the organs composing it are in a state of acti-
vity; and one of the most remarkable facts
which the careful study of this

part of the
structure of the class has afforded, is their com- —

_CRUSTACEA.

= state of doubleness ; on either side of the
y we find an organ perfectly distinct, and
often wholly independent of its fellow ; to such
an extent, indeed, is this carried, that among
the facts with which modern science has been
enriched in regard to the structure of the Crus-
tacea, one by no means the least interesting is
that in which an animal of this class was actu-
ally found presenting in either half of its body a
different sex, each apparatus complete in every
one of its conditions, and even with the whole
of its modifications.*

Another fact, not less striking, is that of the
analogy which exists, at least among the more

Crustaceans, between the male and the
emale reproductive organ. This similarity is
So great that the simple inspection of the organ
is not alone sufficient to inform us always of
its true nature, which in some instances can
only be ascertained by the most carefnl
examination.

The male apparatus consists essentially of an
organ the secreting instrument of the fecunda-
ting fluid, and of an excretory canal variously
modified. These two parts are contained within
the thorax along with nearly the whole mass of
other viscera, and never extend lower down
than the last ring of this region of the body.
They are not always very distinct from one
another, and it frequently happens that the
testis and the excretory canal are confounded
inextricably under the form of a single tube,
nearly identical in its structure from beginning
toend. The length of this canal is occasionally
very great and variously convoluted and con-
torted, so that its relations with the other tho-
racic viscera become excessively multiplied.
This peculiarity we observe very well in the
Maja and the Cancer pagurus (see fig. 418).
The canal, which throughout is single, is
capillary at its commencement, but increases
gradually in its dimensions to its termina-
tion.

In the Astacus fluviatilis, on the contrary,
the two portions of the male reproductive
apparatus are perfectly distinct, and severally
completely developed. The testis (a, fig. 432)
consists of capillary secerning vessels, which
are readily demonstrable, and presents three
lobes, two of which lie forwards upon the
sides of the stomach, and one backwards
underneath the heart. From these three lobes
two excretory canals (b) take their origin. In
the Edriophthalmia the male organ is com-
posed of two or three elongated vesicles, which
terminate in a common excretory canal.

It is in the Cancer pagurus perhaps that the
male organ of generation is most highly de-
veloped. It occupies of itself a large por-
tion of the thorax (fig.418). The testis pre-
sents the appearance of a kind of grape
cluster, formed of four principal lobes, which,
studied minutely, are found to be made
up of an infinity of extremely delicate ver-
‘micular canals, contorted so as to form great
numbers of pellets. This first portion of

* An account of an Hermaphrodite Lobster,
by Dr, Nichols, Philos. Trans, 1730, p. 290.

783

Male organs of the Astacus Fluviatilis.

a, testis; 6, excretory ducts; c, terminal portion
of these ducts; d, orifice; e, last pair of ambu-
latory legs.

the organ is situated in front of the thorax,
and terminates in a primary large convoluted
vessel lying on the side of the stomach ; be-
hind and in connexion with this we perceive
the vas deferens, properly so called; it is a
canal of considerable size, much convoluted,
and of a milky white colour; it traverses the
thorax, still twisting about, penetrates the cell
of the last pair of ambulatory extremities, and
opens outwardly on their basilar piece. This
indeed is the situation in which the copulatory
organs of the Crustacea generally appear.
Still, in many Brachyura of the Catometopa
family, the Ocypoda and Grapsus for ex-
ample, the external opening of the male gene-
rative organ is found on the sternal part of the
last thoracic ring; and there are even several
of these animals in which the efferent canal,
after having attained the external surface in the
basilar articulation of the last pair of ambu-
latory extremities, returns inwards, and pene-
trates by a small groove, which conceals it
until it has attained to that portion of the
sternum which is hidden by the abdomen;
an example of this occurs in the Gongplax.
In the ordinary state the excretory canal termi-
nates on the edges of the opening, but at the
instant of sexual intercourse the extremity of
the canal undergoes a kind of erection, and
by becoming folded upon itself like the finger
of a glove, projects externally, so as to forma
kind of penis adequate to the intromission of
the fecundating fluid. This latter circumstance
was long unknown to naturalists, who were

784

aecustomed to look upon the members of the
first and second abdominal vings as the ex-
ternal male instruments. These two pairs of
extremities, in fact, (fig. 433,) are distinguished

Members of the st and
second Sonia rings of
the Male Maja.

from the rest by their shape, which is styli-
form, and their structure, which is tubular,
being composed of two horny lamine econvo-
luted one upon another, the first ineluding
the second. But direct observation has de-
prived them of all claim to be considered as
fulfilling any office of so much consequenee in
the economy of the Crustacea as that of eon-
veying the fecundating fluid from the body of
the male into that of the female. At the most,
they can only be regarded as organs of excita-
tion, and which the animal may perhaps em-
ploy at the same time to guide the male into
the female organ.

The female reproductive apparatus of the
Crustacea, in its highest state of complication,
consists of an ovary, an oviduct, and copulatory
pouches.

Fig. 434.

Female organs of the Maja Squinado.

"The ovaries in the Decapoda brachyura resem-
ble four cylindrical tubes (a, b, fig. 434) placed
longitudinally in the thorax, and divided into
two symmetrical pairs, each opening into a
distinct oviduct, yet communicating with one
another by a transverse canal (a’), and by
the intimate union of the two posterior tubes
in a portion of their length (6°). The ovi-
ducts, as well as the ovaries, are of a whitish
eclour; they are short, and become united

CRUSTACEA.
in their course to a kind of sac (c), the neck

of which extends to the exterior of the ani-
mal’s) body (d); there is one of these on
each side, and they are known by the name’ of
the copulatory pouches. It is into these reser-
voirs that the male pours the fecundating fluid,
which is here stored up and applied to the
ova as they pass in succession along and out
of the oviducts. These after a course, which

is never long, terminateat the vulve, openings

formed in the sternal pieces of the segment
which supports the third pair of ambulatory
extremities.

The Anomoura and Macroura have no copu-
latory pouches, and their vulve are situated
on the basilar joint of the ambulatory ex-
tremities of the third pair. The mode im
which feeundation is aceomplished in these
genera is consequently much less apparent
than in the Braehyera. Many writers are
of opinion that this operation takes place in
the interior of the ovaries, a process that
appears by no means feasible on account
of the inequality of development of the ova,
which is such, that the last of them are not in
being even long after the first have been ex-
pelled. It would perhaps be more correct te
suppose that feeundation does not take place
till after the ova are laid, which we know to be
the case among the Batrachia and the greater
number of Fishes.

The female Crastacean does not abandon her
eggs after theirextrusion. Those of the Deca-

pods preserve them under their abdomen by
means of the abdominal extremities modified
Fig. 435.

in their structure (fig. 390 and
435); the Edriophthalmia,
again, keep them under their
thorax by means of the fla-
belliform appendages of the
extremities belonging to this
region (fig. 436); whilst the
inferior genera, such as the
Entomostraca, &c. have sus-
pended to the external orifices
either horny tubes or a

a Ventral he female
bein: st

\ \" p>» legs; f, flabetliform ap-

AS) ~=—s pendages which unite so
as to form a cavity des-
tined to contain the ova.

CRUSTACEA.

‘pair of membranous sacs which contain and
transport them from place to place. These
varieties in the accessory organs of gene-
ration, are m many cases sufficient to distin-
guish the sexes: thus, among the Decapoda
brachyura, the females are known at a glance
by their wider abdomen, which is sometimes
of such dimensions as to cover almost the
whole sternum. Sometimes these sexual diffe-
rences extend to the antenne and to various
other organs; sometimes it even influences the
“size, and occasionally, as we have said, the
general external conformation is modified to
such a degree, that the male and the female
of one and the same species have been taken
as types of two distinct genera. There are
some species of which the females only are as
yet known to naturalists.

The ovum appears to be formed in the walls
of the ovary, fom whence it is detached when
it has attained a certain size, and falls into the
cavity of the organ. We have already stated
in what manner it is expelled, and in what
mode fecundation is accomplished in its pas-
sage through the oviducts, or after its extru-
sion. The distinguished German naturalist,
Rathke, {has given particular attention to the
divers phases of the evolution of the egg of
the Astacus fluviatilis, as well before as after its
escape from the ovary and oviduct; and we
believe we cannot conclude this article more
satisfactorily than by presenting our readers
with a simple and brief analysis of his work.*

The first and earliest form under which the
ovum meets the eye in the ovary is that of a
transparent vesicle, its walls of extreme te-
nuity, and filled with a watery fluid. This is
the vesicle of Purkinje. By-and-by there is
another membranous and very thin envelope
formed all round this vesicle, and in the minute
interval that separates the two coverings there
is a second fluid deposited, transparent like
the other at first, but soon becoming opaque,
whitish, and viscid; this is the vitellus or
yolk. As this increases in size, the vesicle of
Purkinje, which still preserves its first dimen-
sions, quits the centre, and goes to be attached
to the circumference, which, at last, it almost
touches at one point. During this time the
vitellus or yolk is eontinually declining in
tran mcy, on account of the formation
of an infinity of globules, which, at length,
transform it into a viscid mass of a deep brown
colour.

During the last stage of its continuance in
tlie ovary the vesicle of Purkinje, disappears,
and the first rudiments of the germ are disco-
vered. This series of changes might induce
the belief that the germ is neither more nor
less than the liquid of the vesicle shed upon
the surface of the vitellus. Its form at first
resembles that of a slight whitish cloud, which,
by slow degrees, changes into an opaque white
spot, well defined, and covering nearly the
sixth part of the entire surface. ed wi

The egg is in the above state at the time it

* Untersuchungen ueber die Bildung und Ent-
wickelung des Flusskrebses, fol. Leipz. 1829.

785

is received into the oviducts. These canals
secrete an albuminous fluid, which surrounds
the vitellus and its envelope, and which itself
becomes covered with a membranous involu-
crum, called the chorion or dermoid envelope
of the ovum. Another membrane still is
thrown around the last, to serve as the means
of attaching the ovum to the false abdominal
extremities of the mother.

When the process of incubation begins
the surface of the yolk is first seen to be
come covered with star-like or serrated spots
whitish in the first instance, and then white,
which by-and-bye disappear entirely. The
germ at the same time is extended uniformly
over the whole surface of the yolk; but again
it seems to collect towards a point under the
form of a white spot, which is the blastoderma.
This spot, after undergoing certain variations
in its form and dimensions, ends by becom-
ing elliptical with a slight furrow in its mid-
dle, shaped like a horse-shoe. This furrow
soon extends; its extremities meet, and its
centre becomes depressed, so as to assume
the appearance of a sacculus of some depth.
The blastoderma enlarges at the same time,
and presents the appearance of a cordiform
spot. Itis at the bottom of the sacculus but
just mentioned, and in the nearest point of
the blastoderma, that the first rudiments of
organs make their appearance.

It is now that the orifice of the sacculus
begins to enlarge; the edges separate; its
bottom rises, so as at length to become pro-
minent, and a small nipple-like elevation ap-
pears upon it, hidden in some measure by the
edge of the sac, which turns out to be the
rudiments of the posterior portion of the body.
At the same epoch there are formed anteriorly,
on either side of the median line, two pairs of
small strap-like bodies, which are by-and-bye
discovered to have been the rudiments of the
antenne, and another pair, which are the ear-
liest vestiges of mandibles. Between the two
anterior antenne an azygous point presents
itself, which is the rudiment of the labrum,
and which, by the progressive development of
the neighbouring parts, shifts by slow degrees
to its final position between the second pair of
antenne.

By slow degrees the blastoderma, the pe-
ripheral portion of which is much thinner and
more transparent than the middle portion, is
seen to extend on the surface of the vitellus,
and at length to envelope it completely. Du-
ring this time the three pairs of spots which
represent the antenne and the mandibles are
growing larger, their edges becoming distinctly
defined, and their extremities are receding
from the surface of the blastoderma, under
the form of a little cylinder, the end of which
before long divides into two. After the an-
tenne have been seen, the peduncles of the eyes
make their appearance, and detach themselves
by degrees from the blastoderma, as the pre-
ceding appendages had done. The nipple-like
projection which we have seen formed at the
bottom of the small blastodermic sac enlarges
at the same time, and assumes the form of an

786

elongated lamina, the free end of which is
turned forwards, and before long advances
nearly to the labrum.

In the space included between the mandibles
and the fold formed by the abdominal lamina
of the embryo, of which we have just spoken,
we now perceive the rudiments of two pairs of
jaws and of the first pair of maxillary extremi-
ties, then of the second pair of these latter or-
gans, and soon afterwards of the third pair.
These appendages appear in the same man-
ner as the antenne, and in proportion as they
are evolved, the fold that marks the origin of
the caudal lamina of the embryo recedes from
the anterior part of the body; by little and little
the basilar portion of the lamina becomes
straightened, so as to gain the same plane as
the remainder of the blastoderma, whilst its
terminal portion continues bent underneath
against the former. The five pairs of ambula-
tory extremities make their appearance succes-
sively in the same manner as the antenne
and the oral appendages; the same may be
said with regard to the abdominal extremi-
ties ; and whilst this formation is going on, the
annular divisions of the abdominal portion of
the body are observed to be evolved. The
carapace at length begins to be formed in
the manner already indicated, and the ex-
tremities, as they sprout, alter their shapes,
and become more and more unlike one
another, as they approach the term of their
embryotic development.

The alimentary canal begins to be formed
by its two opposite extremities. The earliest
traces of the oral aperture are perceived nearly
at the same time as the labrum, under the form
of a small cavity, which becomes continually
deeper and deeper. Some short time after-
wards, and before the appearance of the jaws,
we distinguish towards the summit of the ab-
dominal tubercle, a slight depression which
grows rapidly deeper in order to form the anus.
About the same period a very delicate and
gelatinous-looking membrane begins to be
formed between the inner aspect of the middle
portion of the blastoderma and the vitellus ;
this increases rapidly, and sends prolongations
towards the mouth and anus, which soon be-
come hollowed out into a cavity, and are fi-
nally converted into two small perpendicular
canals. The one of these canals terminating
at the mouth is the commencement of the
cesophagus and stomach ; the other,with which
the anus is soon found to be in connexion, is
the rudiment of the intestine. The rest of the
membrane in question is observed to extend
rapidly and at length completely to envelope
the vitellus. At this epoch of the develop-
ment of the embryo, the sac thus formed
covers the blastoderma, incloses the yolk, and
towards its lower part presents two funnel-like
portions by which it is made to communicate
with the gastric and intestinal portions of the
digestive canal, the formation of which we
have just had occasion to speak of. These
two portions of the digestive canal as they
increase ,in size approach one another; the
rest of the sac folds inwards upon itself, and

CRUSTACEA.

diminishes more and more in size until it
disappears entirely, and the stomach and in-—
testine form one perfectly continuous tube.
At the point where the intestine is connected
with the sac inclosing the yolk, two small
thickenings are seen, which by-and-by acquire
the form of appendages and become covered
with little warty-looking enlargements; this is.
the liver beginning to be formed. The enlarge-
ments of which we have spoken constitute its
lobuli, and these slowly divide into a mul-
titude of long slender vessels. r

The heart begins to be developed about the
same time as the intestinal canal. It makes
its appearance towards the dorsal part of the
body, a short way above the commencement
of the abdomen, and shows itself at first under
the guise of a small pyriform cavity hollowed |
out of a membrane supplied by an inner la-
mina of the blastoderma. The arteries begin .
to show themselves towards the same period
in the substance of this same blastodermie
lamina, and in the beginning present neither
ramifications nor any communication with the
heart. |

We have already spoken of the develop-
ment of the apparatus of respiration and of |
that of the nervous system at such length as
to render it unnecessary to enter farther
upon these parts of the subject here.

The greater number of the Crustacea do not
escape from the membranes of the egg until they
have attained such a perfect state of develop-
ment, that they possess the whole of the organs
they will ever exhibit, and have attained a form
which differs but little from that which is to
distinguish them when arrived at maturity or
become adult. The case, however, is different
as regards some of these animals; these are
born in some sort prematurely, and only attain
their distinctive formation after their exit from
the egg. The changes which they undergo
between the term of their birth and that of
their perfect growth are sometimes so great that |
they are every way deserving of the name of .
metamorphoses.

These changes, whatever their amount, may
depend on the following circumstances :—1. the
continuation of the normal work of development,
which has not been completed in the ovum ;
2. the unequal growth of different parts of the
body; and, 3. the atrophy and complete ulti-
mate disappearance of certain parts.

It is among the lower Crustaceans that this
kind of premature birth takes place most fre-
quently : thus the sugient Crustaceans and the
Entomostraca quit the membranes of the ovum
at a stage of development which corresponds —
with one of the earlier of those under which
the Decapoda present themselves to our notice;
they are all of an oval figure, and only appear —
provided with a very limited number of styli- —
form extremities. The common Cyclops, for —
instance, does not show the posterior part of —
the body at the time of its exclusion from the —
ovum, although this subsequently forms an —
elongated tail; it is nearly spherical at first, <
is provided with no more than two antenna —
and four extremely short feet. It continues —

— —_— ee

a |
Se ee

CYST.

in this state till the fourteenth day, when a
small projection makes its appearance from the
hinder part of the body; on the twenty-second
day it acquires a third pair of extremities, and
on the twenty-eighth day it changes the tegu-
mentary covering of its body.* Several Edrioph-
thalmians are also born before they have ac-
quired the whole of their extremities ; but we
know of no instance of the appearance of one
or more pairs of extremities after exclusion
from the ovum among the superior Crustaceans.

The changes of form which take place in
parts already existing, and which depend on
the unequal rates of increase with which the
different parts of the animal approach their
final state of development, are often very con-
siderable, and commonly tend to occasion
peculiarities of conformation in the adult,
which distinguish it from allied species, and
imprint upon it the character proper to the
tribe, genus, species, and even sex to which
it belongs. These implicate one part in one,
another in another; here it is the thorax
which grows more rapidly than the abdomen
and greatly preponderates; there it is the
abdomen which, smaller at first than the
thorax, increases in dimensions, and finally
exceeds it in size: in other instances, again,
the phenomenon of extraordinary growth is
displayed in certain extremities, or even in
certain articulations of these extremities, which
follow differences in the proportions of the
body and in the forms of its different parts.
These differences contribute in general to in-
crease the dissimilarity which already exists
between the different segments of the body, and
_ may therefore be regarded as a sequence in the
general tendency of these animals to become
more complicated in their structure in propor-
tion as they rise in the series to which they
belong, or in the course they have to run in
order to attain their perfect state.

To conclude: the modifications depending
on the atrophy and the disappearance of certain
parts with which the embryo is provided, tend
also to individualize in a greater and greater
degree the animals which experience them.
As an instance of this phenomenon we may
quote the disappearance of the eyes in certain
Haustellate and certain Edriophthalmian Crus-
taceans, and that of the greater number of the
extremities in a great many of the Lernee.
The Dromiz, among the Decapod anomoura,
have also presented us with an instance of
changes, analogous in their nature and in their
consequences; for among the young animals
the abdomen terminates in a caudal, fan-
shaped fin, as among all the Macroura and
a great many of the Anomoura; but with the
advance of age, the lateral lamine of this
organ disappear, and the abdomen then termi-
nates very nearly as it does in the Brachyura.

It is among the Crustacea which are born in
the most imperfect state, and which conse-
quently have the greatest number of changes
to undergo, that the young animals bear the
greatest resemblance to one another. The
anomalies of conformation encountered among

* Jurine, Histoire des Monocles.

787

these Crustacea do not in general show them-
selves till the latter periods of their growth.

The length of this article (already, perhaps,
too great) does not allow of our pausing longer
on this subject, and we shall only add that the
evolution of the Crustacea is one of the points
in the history of these animals which appears
to promise the most interesting and important
series of facts to whoever will devote himself to
the comparative and extended investigation of
the subject.*

BIBLIOGRAPHY.—Besides the references at the
bottoms of the preceding columns, see Suckow, Anat.
physikalisch Untersuchung ueber Insekten und Crus-
tenthiere, 4to. Heidelb. 1818. Portius, De cancri
fluviatilis partibus genitalibus, Miscel. Acad. Natur.
Curios. Dec. 2, An 1687, p. 48. Gesecke, De
cancri astaci quibusdam partibus, 4to. Gotting.
1817. Kohler, Obs. nonnullas anatomicas, &c. et
in systema vacorum cancri astaci, 8Vvo. Tubing.
1811. Herbst, Naturgeschte der Krabben und
Krebse, 3 Th. 4to. Berl. 1782-1800. Miiller, En-
tomostraca seu insecta testacea, &c. 4to. Kopenh.
1785. Ramdohr, Beytrage zur Naturgeschichte
einiger deutschen Monoculusarten, 8vo. Halle,
1805. Hunter, Catalogue of the Hunterian Col-
lection in the Museum of the Royal College of
Surgeons—Comparative Anatomy and Physiology,

4to. 1831-5.
( H. Milne Edwards. )
CYST. Kystus, (xveris, bladder), Certain

membranous investments, of various forms,
though commonly spheroidal, being shut sacs,
and developed in the midst of other tissues,
have obtained the name of cysts.

Up to the present moment the study of cysts
is so little advanced that we can scarcely dis-
cover any researches which would appear to be
founded upou the observation of nature. Whilst
so much attention has been devoted to the in-
vestigation of many departments of patholo-
gical anatomy, it is difficult to understand why
this very interesting subject has been compara-
tively neglected. The singularity of the cir-
cumstance is not lessened by the reflection that
the rules of therapeutics ought to vary with the
character of these sacs, and that, consequently,
the anatomical study is of first-rate importance
in enabling us to proceed rationally in the treat-
ment of these extraordinary products of the ani-
mal economy.

In describing these organs, two modes have
commonly been employed; the one, to con-
sider them with reference to the product they
contain ; the other, with reference to their pro-
per structure. Itis not our intention to adopt
either of these methods of considering the sub-
ject, and for the following reasons :—it is de-
monstrable that cysts which are identical in
texture frequently envelope totally different
products, and also that the products and the
cysts are susceptible of transformation to an
almost indefinite extent ; and as neither method

* See on this subject the observations of Rathke
already quoted ; those of Thompson, ‘‘ the Meta~
morphoses of the Crustacea;” ourown ‘* Re-
cherches sur les changemens de forme que les
Crustacés subissent dans le jeune age.” (Annales
des Sciences Naturelles, tom. xxx. and 2ne serie,
tom. iii.) and the inquiries of Nordmann in his
Mikrographische Beitrage, &c. 2tes Heft.

788

affords us any facility in distinguishing one
kind of cyst from another, we hold them alike
inadequate to lead to correct views of the sub-
ject. The plan which we propose to follow
may not afford any increased facility in dia-
gnosis, but it is, we apprehend, founded upon
a more stable basis than either of those to
which allusion has been made. We mean to
consider cysts with reference to the mode of
their developement; and although we do not
pretend that this arrangement will afford much
greater facility than at present exists for the
diagnosis of the species, yet it appears to us to
be the most natural classification which, in the
present state of our knowledge, we are enabled
to offer. A considerable assistance in the dia-
gnosis of these organs may be obtained from
the adoption of the following principles, which,
though not unerring in their application, will
afford a very near approximation to the truth,
in the majority of cases. Those ¢ysts which
are external, subcutaneous, and exactly glo-
bular, with a thinning of the dermis, which
seems to adhere to their surface, commonly
contain sebaceous matter of a whitish colour,
friable and semi-concrete ; those which occupy
muscular interstices in the neck, the back, or
the extremities, have, commonly, thin parietes,
are cellulous, of irregular form, and contain
either serosity or albuminous pus, in which
are seen floating opaque flocculent particles ;
those which surround articulations and ten-
dinous sheaths—true appendices of synovial
tissues—are stréngthened externally by fibrous
laminz, lined by a serous tissue, and contain a
more or less pure synovial fluid; those which
ave developed under the anterior annular liga-
ment of the carpus sometimes contain small
whitish bodies, in appearance not unlike a
grain of boiled rice; those which occupy in-
ternal cavities, attaching particularly to the
liver, usually contain hydatids, and to the
ovary contain a variety of products, sometimes
serous, sometimes sanguinolent, sometimes
gelatinous.

Until a better method of diagnosis is pre-
sented, the situation of the organ will therefore
facilitate to some extent the knowledge of its
contents. No one, however, will rest satisfied
with this means, nor underrate the necessity of
pursuing the investigation of these organs, until
we are in a condition to state with more cer-
tainty the elements for their diagnosis.

We believe that all cysts may be ranged
under one of the three following categories. A
cyst may be a simple enlargement, or exagge-
rated developement, or other modification of
an existing organ. It may be produced by the
irritation excited by the presence of a foreign
body, whether that body be a shot or other
substance introduced from without, or a tu-
bercle or other abnormal product developed
within the body. It may be a new formation
not before existing in the economy, and pre-
existent to the matter which it may be after-
wards found to contain.

The last of these categories has not usually
constituted an element in the consideration of
the mode of formation of cysts, and the sub-
ject has in this way been divested of the

CYST.

difficulties which it must otherwise present.
Many accurate observers have expressed a
belief that cysts were a consequence of the
irritation occasioned by a foreign body; inthis
way a large proportion of these organs must
be entirely excluded from consideration, or
must be treated of under the term aeephalocyst. .
Another class of observers, admitting the exist-
ence of the foregoing, have added another
variety :-——they have assumed that the parietes

of an alveolus of cellular tissue are attacked by
some “morbid affection” by which all com-
munication with the adjoining cells is cut off;
that the parietes of this alveolus, under the in-
fluence of irritation, acquire the power of secret-
ing a product entirely different from that which
they furnish in their natural condition ; that the
accumulation of this morbid product causes
a progressive distention of this small cavity, and
a thickening of the cellular lamine in the midst
of which the tumour is developed: in other
words, that the tumour so produced acts in
the same manner as a shot or other body in-
troduced from without. In the opinion that
all cysts are so produced, they are fortified by
the belief that, by the process of maceration, of
inflammation, or of suppuration, it is possible
to reduce the parietes of these organs to their
“ original element, cellular tissue.” Such was
the opinion of Morgagni, Haller, Louis. The
opinion propagated by Bichat, that a certain
uniformity in structure obtains in all cysts,
that they are all analogous to serous mem-
branes, will, it is believed, be found incorrect ;
there are many cysts which in structure and
function are essentially different from serous
tissues, for instance, some are fibrous, cartila-
ginous, osseous, others are cutaneous, others
covered with hair.

Our first class contains the greater number
of those subcutaneous tumours which are so
commonly seen under the integuments of the
cranium, the face, and some other parts of the
body, and which contain meliceric, athero-
matous, steatomatous, or other matter. It has
been over and over again demonstrated that
those follicles which open upon the surface of
the body may have their aperture obliterated :
the secretion from the internal surface of the
organ may still proceed, and they occasionally
attain a considerable volume; in this way
“‘ steatomatous”’ tumours are produced. The
matter contained in these tumours has been
analysed by Thenard, who obtained the fol-
lowing results.

One hundred parts submitted to desiccation
were reduced to forty, which treated by alcohol
were, in fact, dissolved: the alcohol in cooling
deposited a fatty matter, which was easily
melted and was similar to adipocire. The —
residuum, which formed sixteen parts, was of
an albuminous nature; consequently there were _
twenty-four parts of adipocire. This adipocire —
did not crystallise like that of the biliary cal- —
culus in man; it was deposited in flakes like —
those of putrid animal matter dissolved i hy
alcohol: yet, in the matter of the cyst, it was
in the form of very brilliant micaceous la ne.
These cysts frequently appear very thick, but
this great thickness is a consequence of their —

ry
h
"a
{

CYST.

being almost constantly lined by an inorganic
coat, which is sometimes susceptible of being
divided into lamine; when this coat is re-
moved, there remains a very thin cellular mem-
brane. If the lining membrane be irritated,
the secretion as well as the membrane may be
modified ; and the variety of these subcuta-
neous tumours is thus explained.

Other cysts differently formed appear to ar-
range themselves most naturally in this class ;
of such are those which succeed to the ob-
struction of a salivary duct, ranula for instance ;
those which succeed to a fistulous canal, and
are produced by the obliteration of the orifices
of such canal; the mucous tissue by which
the canal was previously invested becomes
changed in its organization, and a serous cha-
racteris acquired :— those which are occasionally
produced in the lungs, by the obliteration of
the canal of communication between a tuber-
cular cavity and a bronchus; in this case
also a serous membrane is developed within
the cavity.

The second class.—Every foreign body, fluid
or solid, formed within or derived from with-
out the animal economy, induces in that eco-
nomy an effort at expulsion. Whether the
body be a shot, a bullet, or other projectile, or
whether it be extravasated blood, stone in the
bladder, the foetus in extra-uterine pregnancy,
acephalocysts, tubercle, or other heterologous
or analogous formation ; in all cases irritation
or inflammation is developed, for the purpose
of expelling or isolating the nocuous body.
If it be in its nature irritating, it excites in-
flammation, and is expelled with the pus which
has been secreted around it; if it have no
mechanically or chemically irritating property,
it may remain in the midst of the organ, some-
times passing from cell to cell, obedient al-
ways to a kind of eccentric movement; some-
times nature isolates it by organising around it
a cyst which is adherent by its external surface
to the surrounding tissues, but which is free
and smooth internally,—furnishing a fluid by
which many of these bodies may be broken
down, and as soon as they are removed, the
walls of the cyst become reduced into cellular
tissue by absorption.

Frequent opportunities are afforded for ex-
amining these structures in the cellular tissue.
When a certain quantity of a succulent fluid is
accumulated in this structure, if it cease to
increase, the parietes of the cavity which con-
tains it continues to be the seat of a chronic
inflammation by which the formation of a cyst
is determined. Until the organisation of this
cyst is perfected, the surrounding cellular tissue
continues red and indurated; but as soon as
the organ is completed, this redness and in-
duration are commonly in progress of dis-
Sipation ; in some cases, however, they remain,
and then it occasionally happens that the cyst
participates in the morbid action, and the in-
terior of the cyst may have a pseudo-membrane
developed on its surface. Cysts so developed
are at their commencement soft, not very con-
sistent, and may be easily detached from the
surrounding structure. The inflamed stratum,
between the cyst and the adjacent healthy

789

tissue, gradually acquires a greater density and
more power of resistance, at the same time
that it becomes thinner, and contracts a more
intimate union with the proper membrane of
the cyst. When the organisation of this spe-
cies of cyst is completed, the membrane is
whitish, opaque, more or less thick, and as a
point of comparison, denser, and thicker than
a serous membrane, and it presents a surface
somewhat similar to that membrane.

In making a third class, it must be obvious
that we incline to the opinion of Delpech,
“that certain cysts do not proceed from an
accidental and mechanical modification of the
cellular tissue,” but that they are so many new
organs, so many newly developed tissues,
which do not possess either the same degree or
even the same kind of vitality as the surround-
ing parts.

In this class we range those which contain
a serous or sero-mucous fluid, which are de-
veloped in various parts of the body. Their
parietes are sometimes transparent, at others
Opaque; upon their inner surface they usually
present a kind of tomentum or velvet-like tex-
ture, sometimes it presents hair. Their ex-
ternal surface is sometimes free on all sides
except that upon which the vascular commu-
nication obtains, sometimes they are com-
pletely adherent. ‘They are observed free and
almost floating in the cerebral cavities, in the
kidney, the liver, the lungs, and in all serous
cavities.

We also include in this class certain syno-
vial cysts, which are observed around the
articulations of the hand, of the foot, some-
times of the knee, and in the neighbourhood
of the sheaths of tendons. Some persons have
been disposed to refer the origin of these
organs to a displacement of the synovial mem-
brane which has yielded at this point; but ob-
servation has demonstrated that they are cysts
with dense and fibrous external, and serous
internal parietes, developed in the cellular
tissue surrounding the normal synovial sac.

In the same class we place a species of cyst
developed, so far as we yet know, under the
anterior annular ligament of the carpal articu-
lation,— more rarely in the vicinity of the
tibio-tarsal articulation, but always around sy-
novial sacs or tendons, and essentially con-
stituted of small white bodies, in appearance
similar to small grains of boiled rice.

Of the serous cysts, we may frequently find
some very small, and, as nearly as may be,
empty, the membrane being puckered and
plicated, and in contact with itself at points
where the plice meet. At a certain period of
their existence there is scarcely a particle of
fluid accumulated in them, and of course the
first exaggerated exhalation which has place
will be lodged without any obstacle in the
cavity, the plice will be effaced, and the pa-
rietes removed to a certain distance, the one
from the other. It is probable that this pro-
portion between the cyst and its contents is
maintained until some irritation shall acce-
lerate the exhalation, much as in the serous
cavities of the body. This exhalation is some-

imes so abundant and rapid that the parietes

790

become irritated and inflamed, and these tunics,
at first characterised by so much tenuity, may,
by the pure and simple effect of their rapid
development, or as a consequence of their
relation with very moveable organs, or by the
effect of accident, to which they are exposed,
become susceptible of almost unlimited trans-
formation.

We believe, therefore, that all the varieties
composing this class owe their existence to
irritation ; in the synovial the irritation is spe-
cific and caused by pressure,—in the serous,
we believe it to be of another kind,—in many
of them it is similar to that which presides
over the development of hydatids: the only
difference between certain of them, those, for
instance, which are so nearly isolated, having
merely a vascular communication, and an
hydatid, is perhaps simply, that their existence
has not been sufficiently prolonged to permit
with safety the rupture of this umbilical cord,
if I may so term it, by which they are con-
nected to the surrounding tissues. We must
now endeavour to explain the circumstances
‘under which these cysts are developed.

The experiments and observations of Cru-
veilhier shew, in the most convincing manner,
that humidity, abundance, and the bad or ve-
getable quality of the nourishment of an
animal, are unequivocal means of producing
acephalocysts. If by the concurrence of these
circumstances acephalocysts may be produced,
it must be evident that by the agency of the
same causes a modification of existing tissues,
— irritation, in fact, of a specific kind, has been
excited by which a state favourable to their
development has been produced. Admitting
then that by such means a particular kind of
irritation may be set up in certain tissues, we
must go further; that irritation must be suf-
ficient to cause the exhalation of a particle of
lymph, that lymph, as in the case of a pseudo-
membrane, becomes organised, acquires step
by step an individual existence, it will be the
minimum of organisation and independent
vitality, but still, when its separation is achieved,
it will be a living being. Supposing this idea
to be correct, it may follow that a variety of
modifications of such products, more or less
independent, may be in a similar manner pro-
duced.

It is certainly difficult to reconcile the mind
to the idea that the process of irritation or of
inflammation can, under any circumstance,
excite the development of an animal possess-
ing to a certain extent an independent ex-
istence, but this is not more difficult than to
conceive that molecules of a plastic living
substance may form organic membranes, and
yet this is demonstrable.

This has been clearly shewn in the article
ApuEsion; in fact, the more we study the
phenomena of organisation, the more we are
impelled to admit a proper vitality in certain
products of living bodies. The analogy which
exists between false membranes and hydatid
sacs appears to be especially calculated to
elucidate this subject. But whilst the false
membrane remains in vital communication with
the individual, the acephalocystic false mem-

CYST.

brane is detached and enjoys an independent
life; the false membrane acquires a vitality
rivalling that.of normal tissues.

We believe, therefore, that a cyst may be
developed, which, as far as general appearance
are concerned, shall be analogous to the ace-
phalocysts, wanting, however, the one great
attribute, independent existence, and having
a vascular communication with the tissue upon
which it is developed: are not those cysts
which are often seen upon the cortical sub-
stance of the kidney, and upon other organs;
of this class or character ?

Dr. Hodgkin* has inferred that those cysts
which are so often found on the surface of the
kidneys owe their existence to the obstruction
of an excretory canal; others have believed
that this fact was demonstrated, because it was
said that their contents had the odour of urine.
Without denying this position, I may state
that the smell of serum and that of limpid
urine are not very dissimilar. If they were a
consequence of the obstruction of an urinary
duct, it is evident, from the size they some-
times attain, that secretion has proceeded after
the obstruction has been developed ; why then
does it not go further? why do they not attain
considerable magnitude ?

In the earlier periods of their existence the
organisation of these bodies is simple, but in
their progress they may experience many mo-
difications. Their internal and external sur-
faces are essentially different; the internal is
usually smooth and polished like serous mem-
branes ; sometimes it is soft, flocculent, and
easily detached: the external is in contact with
cellular tissue, and partakes more or less of its
character, but frequently it acquires a density
which distinctly separates it from the surround-
ing tissue. There is scarcely any form of trans-
formation which may not occur in these organs.
The internal surface occasionally acquires a
very complicated organisation ; it may be co-
vered with hair proceeding from follicles de-
veloped in its parietes, and it may present
other anomalies. The external surface may
acquire a very considerable density, and may
present something like a fibrous appearance,
but upon further investigation we find that it
does not possess any fibre, neither does its
texture offer any linear or radiated arrange-
ment. When once organised, the tunic which
constitutes the cyst enjoys all the attributes
of living tissues, and is susceptible of similar
morbid modifications. It may become in-
flamed, it may degenerate into a cartilaginous
state,_-may become incrusted with phosphate
of lime, converted into erectile tissue,—may
become scirrhous, and so on; and the ex-
halation or secretion may be so changed that —
cysts of similar origin may contain the most
dissimilar products.

BIBLIOGRAPHY.—Cruveilhier, Essai sur Anat,
Path. t.i. p. 202 & seq. Gendrin, Hist. Anat.
des Inflam. t. ii. p. 531. Begin, Dict. de Méd., et

Chir. Path, art. Kyste.
( B. Phillips.) —

* 1 ‘

* Med. Chir. Transact. vol, xv. part 2. p. 270.

DEATH.

DEATH .—(Lat. mors; Gr. 0avaros; Germ.
Tod; Fr. mort; Ital. morte.) This word has
acquired a variety of meanings, which it will
be proper to enumerate, before explaining
the sense to be adopted in the following
article—Death sometimes expresses the time
when an organic body loses the characters
which distinguished it while living ; in which
signification it is the opposite, not of life,
but of birth, or the period when life began ;
this period being dated in the animal either
from the time when it left its ovum or its
parent, or from the very moment of con-
ception; and in the vegetable, either from
its emergence above the earth, or from the
first impulse of germination. In another
acceptation, Death is that altered condition
of an organic body in which it is no longer
the subject of certain processes which con-
stituted its life. Thirdly, it may signify that
series of changes which immediately precede
the cessation of life;—in this meaning, death
is the act or process of dying. Lastly, in the
human subject, the word is employed to express
the separation of the soul from the body. It
will be our object not so much to follow out
these several significations, which would lead
into a very wide if not a vague discussion, as
to consider the precise nature of that condition
of the animal body to which the term Death
in its physiological import is applicable, and
to enquire by what signs that state may be
known to be either impending, or actually
present.

Death in its most restricted sense may be
defined to be that condition which imme-
diately succeeds the abolition of all those ac-

tions or properties which distinguish living
from brute matter, a condition not merely
negative but privative. But death is likewise
applied to certain states of the organic system
in the higher animals, in which the abolition
of the functions is not universal. In the
former sense, an animal is not dead until
every vital action throughout the tissues has
been extinguished; while in the latter, dis-
solution is considered to have taken place
when the circulation and respiration have
ceased, because the cessation of the others
almost uniformly follows. We have here
then an obvious distinction of Death into two
kinds, which will be found to correspond
with a very natural division of the vital actions
into two classes; 1, those which transpire
between the particles of which living bodies
are composed (nutrition and contraction); and
2, those which occur between certain collec-
tions of organic particles, called organs, and
by virtue of which these organs constitute a
whole system—(respiration, circulation, inner-
vation, &c.) The extinction of the former of
these classes of functions we shall venture to
designate Molecular Death; of the latter,
Systemic Death.*

* We should have been glad to have avoided a
word so incorrectly formed as systemic, but its use
ha sbeen sanctioned by too many and too great au-
thorities for us to venture upon the substitution of

791

The following truths respecting the mutual
influence of these two kinds of death will be
illustrated in the course of the present article :
1st, That molecular does not necessarily in-
volve systemic death, unless the former is
universal. 2dly, That when partial, as in
mortification, the tendency of molecular to in-
duce systemic death depends on the import-
ance of the part to the whole. 3dly, That
molecular death in one part can only induce
the same change in another part, by means of
its interference with one of the systemic func-
tions. 4thly, That systemic death must neces-
sarily be followed sooner or later by molecular
death,—but that, 5thly, The reality of systemic
death can only be proved with certainty by
the occurrences pertaining to molecular death.

MOLECULAR DEATH.

Molecular life is constituted by two func-
tions, Nutrition and Contraction, for which
certain conditions are requisite. The former
demands a mechanism or tissue of pores or in-
finitely minute tubes, the ingress and egress
of fluid, and a certain quality of this fluid ;
the latter, a fibrous arrangement of particles,
in most animals and in all a peculiar property
called irritability or contractility. The viola-
tions of these conditions are necessarily fol-
lowed by molecular death. We shall consider
them in detail.

Destruction of the tissues—Itis all buta
truism to assert that the function of a tissue
must cease when its mechanism is broken up,
though mere integrity of the mechanism is
insufficient to maintain the function. The
changes which ensue are as follows. The sub-
stance is no longer capable of receiving and
transmitting fluid in the same manner as for-
merly ; the fluid which it contained is either
confused with the disorganized solid particles, or
is altogether eliminated ; the fibres are unfitted
for contraction ; and the nervous filaments are
paralysed. In this condition the part has ob-
viously no kind of connection with the rest of
the system, by the exchange either of fluid, or
of nervous influence; it is dead both abso-
lutely and relatively. If the other organs sur-
vive its death, certain processes commence in
its immediate vicinity, by means of which a
mechanical as well as a vital separation is
effected; while the mortified part, as it is
technically called, is abandoned to the play of
various chemical affinities among its particles,
and between these and surrounding agents.
According as these changes are less or more ad-
vanced, there is gangrene or sphacelus. It
may happen however that the other parts of
the frame may lose their vitality soon after the
local injury ; but their dissolution will depend
upon the violation of other conditions than
that which we are at present discussing.
Thus the part disorganized may be essential

a newly-created one. The writer is indebted to his
friend Dr. Prichard for the suggestion of somatic,
which is at once correct, and sufficiently characte-
ristic, but he has not had the courage to introduce
it into the text, though supported by an authorit
no less eminent in philology than in general sci-
ence,

792

to the distribution of blood throughout the
system, and the other parts may die from the
want of this supply, their mechanism remain-
ing entire. Or the injury, notwithstanding
that the part may not be thus functionally es-
sential to the circulation, may exert a no less
certain operation, either indirectly by an im-
pression made upon the central organs of in-
nervation, and reflected upon those of circu-
lation and respiration, or immediately by an
impression upon the latter. (See the remarks
upon Systemic Death.) The propagation
of the dissolution will depend much upon the
peculiar organization of the animal; but in
all cases, as we have already intimated, text-
ural death in one part has no immediate in-
fluence in producing the same kind of death
in other parts; the latter event will be found
attributable to the impediment offered by the
former to some important function of the
whole system. The textural lesion which we
have been considering may be caused either by
mechanical violence, or by chemical action,
such as that of corrosive substances and of
heat. It is possible that solid tissue may un-
dergo spontaneous decomposition, but we are
unable to ascertain the fact, because in ulti-
mate structure, where fluids and solids are so
intimately intermixed, we have no means of
distinguishing the priority of changes.

Arrest of the fluid of nutrition.—The access
of this fluid is variously provided for in the
different classes of animals. The capillary cir-
culation in the higher species resembles that
which suffices for the whole system in the
lower species, inasmuch as the blood in the
capillaries of a tissue bears the same relation
to that tissue, as the water in the stomach of
one of the Radiata to the whole animal. The
consequences of abstracting the fluid in the one
case, or of cutting off the supply of blood in
the other by obstructing its vessels, will be pre-
cisely analogous. The polype will desiccate,
lose its proper form, and decay; the medusa
will shrivel and putrefy; while in man the
tissue dies, and is decomposed, as in senile
gangrene, or in the sloughing of a hemorrhoid
to which a ligature has been applied. Sup-
pression of the action of the heart violates
throughout the body the condition of vitality
under discussion, and consequently all the
tissues die, but the phenomena which they
exhibit are not the same as in more partial
obstruction of the circulation, because the
chemical agencies are different, particularly
that of surrounding heat. A gangrenous spot
is under the influence of an atmosphere of 98°
at the lowest; while the dead or dying organs
of animals, which have been simultaneously
deprived of their circulation, are submitted
only to the temperature of the media in which
they may chance to be placed. The higher
this may be within certain limits, the more
closely will the putrefactive changes resemble
those of gangrene. It must be remembered,
however, that in the latter case other chemical
agents are probably presented in the fluids
effused by those contiguous parts which still
maintain their vitality.

DEATH.

Dependence upon the circulation differs in
different animals. The heart of a salamander
may be excised, and yet the animal will live
for several hours, or even a day or two after
the operation ;* its possession of life being in-
ferred from the exhibition, not merely of cer-
tain organic actions, but even of those of rela-
tion. It is plain, then, that in animals of this
tribe, the brain and spinal marrow and other
organs do not require so constant an inter-
course with the blood as in certain other species 5
and while we know with tolerable certainty
that they do not need it for calorific purposes,
it is not improbable that their textures are less
frequently repaired than those of the warm-
blooded classes. Dr. Edwards concludes that
life in the above instance is maintained by the
organs of innervation, whose function, as we
have remarked, continues unimpaired. We
should regard the integrity of their action
rather as a sign than as a cause of continued
vitality ; other signs being perceptible in the
persistence of the capillary actions, for which
the fluids still remaining in the tissues may be
sufficient.

Retention of fluid in the tissues.—Removal
of the effete fluid is provided for in the Porifera
by ejects; in the Polypifera by expulsion from
the central cavity and by transpiration; in the
Acalephe by anal apertures; and in vascular
animals by vessels especially appropriated to
the purpose, by transpiration, and by various
excretions.. This condition of molecular life
is less easily violated than those already spo-
ken of, because the modes of fulfilling it are
more numerous. This is equally true whether
we speak of the simple animal forms, or of the
tissues of the more complicated ; mortification
is less frequently the result of venous than of
arterial obstruction. Unquestionably turgescence
and inflammation may ensue from the former,
and may terminate in gangrene; but it is far
more common for the part to be relieved by
the excretion of various fluids, constituting
hemorrhage and dropsy, until new channels are
found for the returning blood. Hence it ap-
pears that a redundance of fluid is less dan-
gerous to organic structures than a deficiency.

Depravation of the fluid of nutrition —lt
is obvious that as the structures are elaborated
either from the blood in the higher animals, or __
from the fluids corresponding to it in the in- —
ferior classes, the assimilative processes must
be deranged and ultimately brought to a stop, —
if the liquids are wanting in the proper mate-
rials. Their quality may be deteriorated in
various modes; by imperfect respiration, by
bad or scanty alimentation, and by insufficient
or excessive excretion. Each of these causes —
is traced easily enough in the degenerated tex-
tures of some animals, but with more difficulty
in the simpler classes, because the functions —
just alluded to are not in the latter concen-—
trated within a space that admits of analysis so
well as in the former. The effect of obstructed |
aeration of the blood however is soon mani-

* Edwards, On the Influence of Physical Agents,
&e, translated by Drs. Hodgkin and Fisher.

DEATH. *.

fested even in the lowest grades. But we must
observe, that throughout the whole range of
animal existence we can more readily ascertain
the changes produced in molecular action by
diminished respiration, than by the entire sus-
pension of this function ; because, in the first
place, the arrest of the circulation so soon fol-
lows that of respiration, that the subsequent
events are assignable rather to the former than
- to the latter; and in the second place, it is.
impossible to cause one portion of the body
to receive unaerated, while the others are sup-
plied with aerated blood, since the function is
im some animals too concentrated to allow of an
operation calculated to act upon an isolated
part, and in other animals too diffuse to enable
us to interfere with it effectually in any given
Space. In the one case we run the risk of
cutting off the supply of blood from the whole
animal; in the other we should find it im-
ggg to prevent any one part from receiving
rom other parts a compensation for what it
loses by the obstruction of its own particular
allotment of the respiratory function. Nothing
however is more common than to witness the
degeneration of structure produced by blood
insufficiently arterialized, the imperfection of
the process depending either upon disorder in
the organs of respiration, or upon a vitiated
condition of the atmosphere. From facts of
this nature it is legitimate to infer that were it
possible for unarterialized blood to circulate,
the death of the tissues must sooner or later
ensue. Of the destructive tendency of blood
depraved by the other causes above enu-
merated we can likewise judge approxima-
tively; in other words, while there can be no
> sepa of the deterioration of structures under
he operation of those causes, we are not ac-
quainted with any instances in which we can
attribute solely to their agency the entire cessa-
tion of molecular actions. It almost always
epyens that other functions have previously ~
failed, and influenced the result in question.
Extinction of irritability.—Irritability might
at first seem rather the result of vitality than
‘one of its conditions ; but whether we look at
the textural motions in a complex animal, or at
their analogues in the entire systems of the
simpler forms,-we shall find irritability to be
essential to the continuance of those processes
in which living action consists. The alimen-
tary cavity which contracts upon the nutrient
fluid of the zoophyte is no less essential to the
existence of the latter, than a similar action of
capillary tubes in the tissues of mammalia. In
each case the action is requisite, in order to
bring the particles within the spheres of the
textural affinities. The extinction of irritability
is therefore necessarily productive of molecular
death. In this instance we are compelled to
atte of the privation of a property instead of
fining the actual change in the part, because
at present it is not ascertained what condition
of the part is capable of producing contraction.
Irritability is merely an expression of the fact
that the substance of which it is predicated,
undergoes contractions inexplicable on common

physical principles. We detect nothing in the
VOL. T, |

793

substance, the existence of which enables us

to pronounce with certainty that it may be the

subject of the actions alluded to. Some have
maintained that irritability ought to be ad-
mitted as an ultimate fact, of which we know
as much as of gravity. But we apprehend that
there is this great difference in our knowledge
of the two properties, viz. that although igno-
rant of the cause of the attraction of gravitation,
we are certain that the phenomena are co-
extensive with the essential properties of mat-
ter; but we are utterly unacquainted with that
collection of properties to which irritability
necessarily belongs. The muscle which has
ceased to quiver under the galvanic wire is,
for all that we can tell to the contrary, the
same in composition as that which is still ca-
pable of exhibiting the phenomenon. More-
over the action is observed in a great variety
of tissues, both in individual animals, and in
the whole series ; tissues which appear to have
little in common saving a fibrous arrangement
of their particles. But as the action in question
is stopped by causes which in no way affect
the fibre as such, it is plain that this is not the
only requisite. Moreover there are unequi-
vocal exhibitions of contractility in animals, in
which it is difficult to imagine that there can
be any shortening of fibres; we allude to the
Infusoria, Rotifera, Meduse, &c. Tiedemann
makes a separate species of this contractility,
under the designation of “ contractilité des
animaux gélatineux.”* There is reason to
suspect that ganglionic tissue is importantly
concerned in the action, partly because it is
almost universally distributed through irritable
substances, and partly because contraction is
prevented by causes which operate upon this
tissue. As long however as there are animals
which manifest contractions, but in which no
such tissue can be detected, it is impossible to
consider the latter an essential element in the
action generally; though it may be quite es-
sential in the animals in which it is found;
just as a heart, though by no means necessary

to the function of circulation in the abstract, is

indispensable in the animal of whose system it
forms a part.

Irritability may be destroyed by substances,
either applied directly to the part or acting
upon the general system. Thus, the fibres of
the heart may be paralysed by a solution of
opium injected into its cavities, or by essential
oil of tobacco given by the mouth. Light-
ning annihilates the property all over the body.
The motions of Infusoria may be arrested by a
shock of galvanism,t by solutions of opium
and camphor, and by the vapour of sulphur.
Arsenical preparations have a similar effect.
The contractions of capillary vessels in the
higher animals may be arrested by a certain
description of injuries of the brain and spinal
marrow.{ But it is needless to multiply ex-
amples.

* Traité complet de Physiologie de 1’ Homme, tra-
duit de l’Allemand par A. J. L. Jourdan, D.M.P.
2de partie, p. 782.

+ Tiedemann, p. 617. ;

+ See Wilson Philip on the Vital See

F

794 Z

Such then are the causes of molecular death.
For a rages | of its phenomena, when partial,
we must refer to the article Mortirication.
Tts characters when universal, that is, when the
consequence of systemic death, will be con-
sidered when we come to speak of the signs of
the reality of death.

SYSTEMIC DEATH.

Systemic life is constituted by those actions
which maintain the mutual dependence of the
several parts of the organic whole. Such are
the functions which provide new matter for
the blood, (digestive secretion and absorp-
tion)—that which effects a chemical change in
the blood, (respiration)—that which distri-
butes it through the organs and tissues, (cir-
culation cardiac, arterial, capillary, and venous)
—that which removes from the blood effete
matters, (excretive secretion)—and_ that which
is intimately connected with all these functions,
though we are ignorant of the mode of its
operation, viz. the function of nervous matter
or innervation. The cessation of these actions,
and the consequent solution of connection
between the various parts of the body, is sys-
temic death. With the cessation of the re-
maining functions, or those which maintain
certain relations between the organic body
and objects external to it, constituting the
animal life of Bichat, and the relative life of
others, we have nothing to do in this place.
(See Sizep.)

The obstruction of any one of the functions
above enumerated must in a longer or shorter
space of time bring the others to a termination.
But, as the arrest of the circulation acts upon
the other functions immediately, while the
latter affect one another merely by the inter-
vention of the former, we may very properly
consider the causes of systemic death under
the general head of Syncope.

1. Syncope by asphyxia.— We shall not
stop to inquire in what manner the suppres-
sion of respiration arrests the action of the
heart, as the question has been very fully and
satisfactorily considered in thearticle Aspayx1a.
For the same reason we shall waive the dis-
cussion of the accidental causes of this state,
viz. strangulation, submersion, &c. &c. The
diseases which are said to produce death by
asphyxia are those in which syncope would not
supervene when it does, but for the obstruc-
tion of the respiration. They are for the most
part affections either of the respiratory ap-
paratus itself, or of the brain and spinal mar-
row ; and it is almost superfluous to add that
they prevent the intercourse between the blood
and pure air, either by blocking up the air-
passages, or by stopping those muscular actions
which are essential to a change in the contents
of the pulmonary tubes and cells. Certain
organic diseases of the heart itself are said to
produce death by asphyxia. In these cases
there is an obstruction to the motion of the
blood through the left side of the heart; and
in the majority of them the asphyxial sym-
ptoms are not so much the direct effects of the
impediment in the heart, as of the intermediate
pulmonary affections, some of the most fre-

DEATH.

more particularly to various phenomena be-

quent of which are bronchitis, edema of the
lung, and pulmonary apoplery: When, how-
ever, a person dies denly, with asphyxial
symptoms resulting from an arrest of the circu-
lation at the left side of the heart, without any
intervening derangement in the organs of re.
spiration, the case ought not to be considere
an instance of genuine asphyxia. The <

pearances imitative of this state (we allude

longing to venous congestion) are not occa-
sioned as in true asphyxia by the stagnation
of blood in the extremities of the pulmonary
arteries, the consequence of its not _
arterialized, but by the obstacle presente

to the currents in the trunks of the pul-
monary veins by the lesion of the heart.
In_brief, the anatomical difference in the two
states is, that in the one the pulmonary arte-
ries only, in the other both these and the
pulmonary veins are the seats of congestion;
the physiological distinction is, that in the
former the obstruction is chemical, in the latter
mechanical.

2. Syncope by nervous lesions.—The various
parts of an animal body are bound together
by a reciprocity of action, over and above that
particular connection which exists between
certain organs, and which results from a mu-
tual subservience of function. In the latter,
the association is perceptible in the normal
condition of the body, as, for instance, be-
tween the organs of digestion and those of
secretion, or of digestion and sanguifaction,
or in the sympathetic actions of the respiratory
muscles ; but the other species of connection
is only or chiefly observed in morbid con-
ditions; in other words, it is only when dan-
ger is threatened to one organ that the others
give tokens of their intimacy and of their
interest in its well-being. But for our know-
ledge of the existence of this community of —
feeling (a phrase to be taken only in a me-
taphorical sense), it would be impossible to
throw any light upon the fatal consequences ~
of a great number of diseases and injuries.
There can be little doubt that in all states of
the system it contributes very materially tothe
production of that individuality which is one
of the grand characteristics of organic beings,
and which becomes more and more obvious as
our survey rises to the higher departments of
the animal kingdom. There is a manifest in-
equality in this respect, even among the su-
perior classes of animals. Many lesions that
would be fatal to birds and Mammalia, are
comparatively trivial to reptiles, not so much —
because the injured part is of less importance —
in the functional arrangements of the latter,
as because other parts have less sympathy —
with it. ball

There is no subject in the whole range of —
Physiology more beset with difficulties than the
inquiry into the causation of sympathy. Vas-
cular connection has been thought by some to
explain the secret sufficiently, by others the
contiguity or continuity of tissues. Som
have seen the media of communication in the
ganglionic nerves, others in the nerves called

DEATH.

respiratory. We cannot enter into the discus-
sion, and therefore refer to the article Sym-
PaTHy. But we beg to state that we have no
where seen the subject treated with more eru-
dition and acuteness, than in Dr. Fletcher’s
Rudiments of Physiolegy.*

But while there arf no question that all
the organs are more or less related in the man-
ner above indicated, it is not less evident that
the connection between some is of a far more
intimate nature than between others. It is
almost needless to instance the brain and the
stomach, the brain, spinal marrow, and the
heart, the heart and every part of the system,
&e. &c. By overlooking the sympathetic re-
lation between the brain and the heart, Bichat
fancied that when he had proved the functional
independence of the latter organ, he was com-

lled to search in some third for the link

ween the death of the one and that of the
other.+ It cannot be denied that in a large
eae of cases, the syncope which follows
esions of the cerebro-spinal system, is not a
direct consequence, and that there is an in-
termediate suppression of the function of the
lungs,—that in other words the syncope is the
effect of asphyxia.{ (See Aspuyxia.) It is
somewhat remarkable that the illustrious phy-
siologist just mentioned should have forgotten
certain pathological facts which afford con-
vincing evidence that cerebral injury may pro-
duce death without developing the phenomena
of asphyxia; the “ apoplexie foudroyante,”
for example, and the concussion of a blow or
a fall. Nor is it less surprising that in his
_ humerous experiments upon animals he should
not have noticed what was afterwards fully
demonstrated by Legallois and W. Philip, that
both the heart and the capillaries may be imme-
diately paralysed by violence done to the brain
and spinal marrow. It must be remembered,
however, that this result is much affected both
cag extent and by the nature of the injury.
Thus the brain may be sliced and the spinal
cord divided, with no other influence upon the
circulation than that which depends upon the
interference with the respiratory actions; but
laceration or crushing of the cerebral matter
is immediately felt by the heart and capil-
laries. In these cases the circulation ceases,
not because the cerebro-spinal axis takes any
part in that function, but because it is con-
nected with the heart in the same manner as
_we have stated that all the parts of the body
are more or less connected,— in bonds of
alliance though not of dependence. We have
_ reason, however, to believe that the intimacy
of the alliance between the brain and the heart

* Part ii. chap. vi.
Recherches sur la Vie et la Mort, art. xii. §2.
H We must not forget that even in many of these
cases there is no immediate communication of
mary from the part primarily affected to the organs
f respiration. ‘Thus, when a slight hemorrhage
in one of the hemispheres of the brain occasions
asphyxia, we are bound to believe that there is in
the first place a sympathetic communication of de-
rangement to the medulla oblongata, unless the
hemorrhage has been so considerable as to cause
compression of the whole encephalic mass.

795

is scarcely equalled by that of any other organs
in the system.

The anatomical characters of syncope by
nervous lesion are determined by the modus
operandi of the injury. If the latter arrests
the action of the heart only by obstructing the
respiratory movements, the appearances are
those of asphyxia, (see Aspuyxia.) But if
the operation be immediately upon the heart,
there will be a difference in the appear-
ances,——a_ difference which likewise be-
longs to all cases in which the circulation
ceases without previous obstruction of respi-
ration. The blood, instead of being accumu-
lated in the right cavities of the heart, and in
the pulmonary arteries, is more equally dis-
tributed between these and the left cavities,
and the pulmonary veins. There is generally
a perceptible difference in the colour of the
blood in the two sides of the heart, but some-
what less than might at first be expected. The
defect of arterial tint in the coagula of the
left side may be fairly attributed to the drain-
ing away of the serum, and consequently
with it of the saline particles upon the pre-
sence of which the red colour depends. Blood
is found in the aorta and in many of the ar-
teries. The signs produced by venous con-
gestion, such as engorgement of the liver and
spleen, turgescence of the cerebral veins and
of those of the mucous membranes, are want-
ing, as well as the tumefaction of the face,
the puffing of the lips, the projection of the
eyes, and the deep lividities characteristic of
that condition. e must remember that the
appearances are considerably modified if syn-
cope has taken place gradually. In such in-
stances the heart is generally found empty.
The cause of this condition is obvious. In
the first place, as the degree of the diastole
must be proportionate to the systole, it is
obvious that when the latter is enfeebled, less
blood will be received into the cavities; and,
secondly, as less blood is driven into the pul-
monary artery and the aorta, there will be less
to return in a given space of time, and con-
sequently there will be less impetus in the
returning currents. It is easy to perceive that
before the final and feeblest contraction, which
must be succeeded by a correspondently slight
dilatation, the current of blood pressing for
admission must be very trifling.

3. Syncope by injuries of the heart itself.—
This is of too obvious a nature to require
comment. .

4. Syncope by injuries of other organs and
tissues—When death follows quickly upona
lesion which does not necessarily implicate the
vital organs, properly so called, we say in ge-
neral terms that a shock has been given to the
nervous system, in consequence of the strong
probability that some portion of this system is
the agent of sympathy. If violent pain at-
tends the injury, and to this succeeds loss
of consciousness, and then cessation of the
heart’s action, it is fair to infer that the brain
was first operated upon through the nerves of
sensation, and that the derangement of this
organ affected the ee But there are

F 2

796 DEATH.

cases of injury in which syncope occurs with-
out any antecedence of pain or of leipothymia,
and in which there is no reason for supposing
any cerebral affection in the chain of events.
Of this kind are extensive mechanical injuries
of the extremities, burns, rupture or over-dis-
tention of the stomach, &c. Whether the
nerves which convey the morbid impression
belong to the ganglionic or to the respiratory
class, we do not profess to decide. ‘The im-
mediately fatal effect of a blow upon the epi-
gastrium or ofa draught of cold water when the
body is heated, has been attributed by some
to a shock given to the semilunar ganglion,
and the communication of the impression to
the heart; while others are of opinion that the
injury is fatal by “ paralysing the whole res-
piratory set of nerves from the violent shock
com municated to the phrenic, -and thus, shut-
ting up as it were the fountain of all the
sympathetic actions of the body.”* “ A blow
on the pit of the stomach,” says Sir Charles
Bell, “doubles up the bruiser and occasions
the gasping and crowing, which sufficiently
indicate the course of the injury—a little more
severe, and the blow is fatal. A man broken
on the wheel suffers dreadful blows, and his
bones are broken, but life endures—the coup-
de-grace is a blow on the stomach.”

5. Syncope by mental emotion.—Instances
of this occurrence must be familiar to every
one both by reading and by observation. In
some of them the cause in question has
operated either by aggravating some pre-exist-
ing malady, or by calling into action some
strong predisposition to disease; as in struc-
tural lesions of the heart on the one hand, and
in the apoplectic diathesis on the other. But
in other instances the mere violence of a pas-
sion has at once extinguished its subject with-
out the intervention of morbid tendency or of
actual disease. Such cases belong to the
Nervous Apoplexy of some authors; and cer-
tain it is that they present a complete annihi-
lation of sense and motion, but this condition
is only simultaneous with, or immediately suc-
ceeded by the failure of the circulation. We
have no doubt that the change in the organ of
the mind, corresponding to the emotion, ope-
rates upon other parts of the cerebro-spinal
axis, which in their turn affect the heart in the
same manner as other preternatural states of
that system. We are not acquainted with an
example in which either high intellectual ex-
citement unaccompanied by vehemence of pas-
sion, or mere intensity of external sensation,
has been the cause of sudden death; nor could
it be expected a priori, since in the normal
condition of the economy there is by no means
the same degree of connection between the
action of the heart and intellectual and sen-
sific conditions, as between the former and the
emotions and affections.

6. Syncope by hemorrhage.—The functions
of the brain are in man so dependent upon a
regular supply of blood to the organ, that a
sudden diminution of it is alone sufficient to

* Dr. Fletcher, op. cit. partii. chap. 6, p. 60,

it not for the important fact that hemorrhage

oceasion vertigo and: unconsciousness; and
this occurrence often takes place when the
action of the heart itself is little or not at all
affected. Every one is acquainted with the
effect of a change in the relative quantity of the
blood in the cerebral vessels, determined by
suddenly rising from the recumbent posture.

Now it has been often observed that vertigo in-

duced by other causes has been followed by

suspension of the circulation; that is to say,
the state of the brain, which was attended by
giddiness, arrested the motions of the heart.
It has therefore been inferred that loss of blood
operates indirectly upon the heart through the
affection of the brain. When two phenomena
follow each other in such quick succession as
to be all but simultaneous, it is difficult to
determine which is cause and which is effect,
or whether they may not be the common ef-
fects of some other event. Certain facts
would seem to indicate that the latter is the
true interpretation of the phenomena which
we are considering. Thus hemorrhage some-
times affects the nervous system in the manner
alluded to, without presenting any check to
the contractions of the heart; not to mention
that it appears more consistent with analogy to
conclude that the heart must be more directly
influenced by the loss of that which is its
natural stimulus, than by a change in a
remote organ. Again, there are cases in
which hemorrhage makes a decided impres-
sion upon the organs of circulation before the
brain has given signs of any material derange-
ment of its functions; but’in these the loss
of blood is more gradual than in the former
instances. “When hemorrhage is very gra-
dual,” says Dr. Alison, “ all the indications
of failure of the circulation may come on—the
feebleness of muscular action,—the paleness
and. collapse of the countenance,—the cold-
ness beginning at the extremities,—the cold
sweat beginning on the face,—and the pulse
may become imperceptible; without the
senses or the intellect being impaired, and a
slightly laborious or heaving respiration may
be almost the only indication of injury of the
nervous system up to the moment of death.” *
From facts of this description we should be
willing to decide at once that it is a superfluous
multiplication of causes to attribute the stop-
page of the circulation in any case of hemor-
rhage to the influence of cerebral changes, when
the direct operation of the cause upon the heart
itself is adequate to the explanation ;—were

4
tL

alone often fails to produce syncope tillsome —
circumstance has intervened, the operation of —
which is manifestly upon the nervous system. —
Thus nothing is more common in bloodletting —
than to find the heart unaffected by the with- —
drawal of a considerable quantity of its stimu-
lus, so long as the posture of the body i

horizontal ; but on raising the head, a ch
which for obvious reasons renders the bri

* Outlines of Physiology and Pathology, p. 3
This work contains a most valuable chapter
the causes of sudden death.

DEATH.

more sensible of the loss of blood, the nervous
symptoms, viz. vertigo and leipothymia, ap-
pear, and immediately afterwards the pulse
falls and becomes imperceptible. In corro-
boration of this fact we might at first be
inclined to mention that a diminution of the
yr of the blood, so far from depressing
the circulation, often appears to excite it
violently, as in what has been denominated
hemorrhagic reaction; but in such instances
analogous effects have been also witnessed in
the cerebral functions, namely, delirium and
extreme sensibility, &c. On the whole we
may conclude with regard to both these sys-
tems that the depressing effect of hemorrhage
depends rather upon the suddenness of the
change, than upon the absolute diminution
of the quantity of the fluid.

7. Syncope by poisons.—Some_ substances
depress the action of the heart in the man-
ner to which we had occasion to refer when
A agri of syncope by mechanical injuries of
the tissues generally. Of this kind are the
mineral acids, oxalic acid, and the pure
alkalies. They produce death, when taken
in certain quantities, by means of that de-
pression of the circulation which follows
the destruction of the parts to which they
are applied. In smaller quantities they may
be more remotely fatal by exciting disease,
gastro-enteritis for instance. One of the sub-
stances mentioned, viz. oxalic; acid, may in-
duce direct depression of the circulation, un-
attended by cerebral affection, even when its
chemical effect upon the stomach is prevented
by dilution. In this form it must be classed
- with a large collection of substances which in
certain doses subdue the moving powers of
the circulation, without any previous coma,
without any alteration of the tissues, and
without any gastric irritation; such are arse-
nic in large quantities, tobacco, digitalis, and
most of the animal poisons. To the same
class belong those malarious and contagious
poisons which occasionally induce fatal syn-
cope before any of their ordinary effects upon
the general functions; we scarcely need to
mention cholera, malignant typhus, plague,
scarlatina, &c. The narcotic substances mani-
festly act first upon the cerebro-spinal system ;
‘syncope follows either with ‘or without as-
phyxia. Those which act rapidly appear to
strike the circulation before asphyxia has had
time to transpire; we may instance hydro-
eyanic acid, essential oil of almonds, large doses
of opium and of alcohol, certain gases, par-
ticularly sulphuretted hydrogen and cyanogen.

8. Syncope by cold and lightning.—lIt is
not clear whether these outward agents arrest
the circulation through their influence upon
the nervous system, or by directly paralysing
the irritability of the fibres of the heart.

9. Syncope by inanition—In cases of this
description it is probable that the failure of the
heart’s action is a compound result of the
prostration of the nervous system, and of the
diminution of the proper stimulus of the
circulation.

10. Syncope by disease —All fatal maladies

707

must terminate in cessation of the heart’sa c-
tion, but we limit the present category to those
cases in which this event is unpreceded by
asphyxia. The others have been hinted at
under the head of syncope by asphyxia. The
diseases now under consideration may, we
think, be conveniently arranged as follows :—
I. Those which stop the motion of the heart
by obstructing its mechanism, e. g. collections
of fluid in the pericardium, lesions of the val-
vular apparatus ; accumulation of fat, &c.; or
by diminishing the contractility of the fibres,
e.g. atrophy, or degeneration of the muscular
substance ;* or by perturbing in some unex-
plained manner the nervous influence, e. g. the
functional form of angina pectoris. 2. Those
which are attended with hemorrhage, e. g.
aneurisms, and diseases of mucous surfaces.
3. Those which induce excessive and long-con-
tinued discharges. Thus fatal syncope has sud-
denly terminated a fit of diarrhoea ; but it must be
borne in mind that in such instances the power
of the circulation had previously been greatly
enfeebled either by deterioration of the blood,
or by causes acting on the innervation of the
heart, or by the existence of irritation in some
part of the system. 4. Diseases implicating
the cerebro-spinal organs. Some of these ope-
rate in the same manner as those accidental
injuries which produce concussion, and which
have been already adverted to. Thus in that
species of apoplexy which terminates instan-
taneously, (apoplerie foudroyante of French
authors,) the sanguineous extravasation appears
to have the same effect as a mechanical shock
to the whole nervous mass. The more common
form of apoplexy extinguishes life by impeding
the respiratory movements. We have more
than once known cases of structural disease of
the brain terminate by sudden syncope, but
have learned nothing from the necroscopy
capable of explaining why the fatal occurrence
took place at the precise time when it did,
rather than at any other moment in the period
during which the disease had existed; though
it was easy to conceive that a lesion of this
description must have been competent at any
time to produce such changes in the cere-
bral circulation as would induce the result
in question. 5. Diseases attended with what
has been vaguely called irritation, either short
and intense, or moderate but long-continued.
This irritation consists sometimes of inflam-
mation and its sequel, and sometimes of spe-

“cific structural alterations. A good illustration

of the former of these is afforded by peritonitis,
which frequently cuts off the patient by sub-
duing the action of the heart, long before this
effect could transpire from derangements of the
organs contiguous to the seat of disease. Still
more remarkable in this point of view are the
effects of acute inflammation of a synovial
capsule. -It is true that these affections are
accompanied by violent pain, which might be
said in common language to exhaust the
powers of the system, or in stricter phrase, to

* See Mr. Chevalier’s interesting cases of sudden
death in the Med. Ch, Trans. vol. i.

798

produce a change in the nervous system in-
compatible with the continuance of the action
of the heart; but mere pain will not account
for the fact in question, since in other diseases
it attains a more intense degree, and lasts
longer, as in neuralgia, without inducing fatal
consequences. The causation is probably
analogous to that of syncope from mechanical
injuries of tissues, to which we have already
devoted some remarks. But why an inflam-
matory condition of serous membranes should
exert a more depressing influence upon the
circulation than that of many other tissues that
might be named, is a subject wrapped in deep
obscurity ; yet it is scarcely darker than the
question, why such changes should in the first
instance excite and perturb the heart, or why a
similar excitement should ensue upon the soft-
ening of a cluster of tubercles, and tu a degree
inexplicable by the functional derangement
of the part in which the tubercles exist. Dis-
eases in which the powers of the system are
said to be worn out, are in reality such as have
gradually enfeebled the action of the heart,
partly perhaps through the intervention of
changes affecting the blood, the respiration and
the nervous system, but probably in a great
measure by as direct a relation between the
diseased part and the change in the circulation,
as between vivlent lesions of tissue and syn-
cope. Under the present head are included
a host of chronic maladies. 6. Diseases
caused by vitiation of the blood. Such are
scorbutus, certain forms of marasmus, the
cachexie revealed by dropsies, and certain
fevers of a malignant character. We might
also mention those depravations indicated by
morbid secretions, such as tubercle, carcinoma,

melanosis, &c. but that the solids are so much ©

involved in these diseases, that it becomes
difficult to determine whether the heart’s action
was weakened by the primary lesion of the
blood, or by the secondary one of the tissues,
7. Diseases which produce vitiation of the
blood. Such are that large class in which
there is disorder of the chylopoietic processes,
and that smaller group in which the convey-
ance of the chyle is impeded. Derangements
of the secernent and excernent organs must be
arranged in this division, and particularly
those of the liver, the skin, and the urinary
apparatus. Diabetes is a state of the system
in which the blood is probably deteriorated
both by defective assimilation, and by faulty
excretion. Upon the whole of this class of
diseases it must be remarked that we seldom
or never have opportunities of witnessing their
uncombined influence in depressing the organs
of circulation. ;

11. Syncope by old age.—We have, in a for-
mer article (AcE) endeavoured to trace the
principal events in senile decay. The death
which follows this gradual decline of the func-
tions, presents the strongest possible contrast
to that of sudden syncope. In the latter in-
stance the assault is made upon the very citadel
of life, the conquest of which secures an im-
mediate surrender of the minor bulwarks and
dependencies ; but in the former the fortress is

DEATH.

reduced only after a long series of defections in
the outworks, and a consequent loss of supplies,
or, to quote the words of an illustrious author,
“Voici donc la grande différence qui dis-
tingue la mort de vieillesse, d’avec celle qui
est l’effet d’un coup subit ; c’est que dans l’une,
la vie commence a s’éteindre dans toutes les
parties, et cesse ensuite dans le cur; la mort
exerce son empire de la circonférence au
centre. Dans l'autre, la vie s’éteint dans le
ceeur, et ensuite dans toutes les parties; c’est
du centre 4 la circonférence que la mort en- —
chaine ses phénoménes.”*
SIGNS OF APPROACHING DEATH.

It would be tedious and altogether beyond
the compass of this work to enumerate all the
phenomena presented by the dying system,
since they vary with the cause of death. We
shall aim rather at describing and accounting
for those which are common to most diseases
and to natural decay; reserving to ourselves
the liberty of noticing here and there some of
the more striking varieties.

We might rationally expect that the first
indications of dissolution would appear in the
relative functions ; hebetude of the senses, in-
action of the muscles, vacancy of the intellect,
extinction of the sentiments; and such is, in
fact, the course of events in natural death.
We have known the aged man remain feeling-
less, motionless, mindless, for many days be-

‘fore the cessation of the organic functions.

This kind of death is sometimes imitated by
apoplexy; but in the former the destruction of
the animal life does not, as in the latter, arise
from a lesion of the brain; its organs appear to
undergo a gradual process of enfeeblement. Tn
many febrile maladies there is the same priority
of failure on the part of the cerebral functions,
but they are generally preceded by more or less
actual disease of the organ. But in the termi-
nation of some disorders the functions alluded
to continue to the very last, almost surviving
the circulation itself. It will be found however
that the seat of such disorders was remote from
the encephalon, that it did not communicate with
the latter by any special sympathy, and that
the extinction of the cerebral functions was at-
tributable to the arrest of circulation in that
organ, in common with many others. The
cases in which the mind is said to continue
clear and vigorous amid the ruin of the body, ~
will be found to agree in the fact that the —
organ is correspondently unimpaired; they are
for the most part chronic diseases of the thorax,
abdomen, pelvis, and extremities. Certain
affections even of the cerebro-spinal system —
may not interfere with the understanding and
feelings until almost the last moments; but
they are such as do not involve those divisions
with which, thought is believed to be more
immediately connected: We may instance
tetanus. But although in these maladies we
do occasionally observe considerable intellec-
tual soundness till within a very slort period
of death, we have far more commonly been
able to detect some degree of delirium, an

DEATH.

exaltation of one part of the mental constitution
at the expense of the others. Excitement of
the imagination has,-we doubt not, been fre-
quently mistaken for general mental vigour.
We should place such instances, however, far
below those in which there remains sufficient
steadiness of the understanding to direct the
provisions of a will; though by many observers
such a condition of the intellect would be con-
sidered a far slighter evidence of the triumphs
of mind over matter, than the impassioned
expressions to which the dying man sometimes
gives utterance, when describing the visions of

his * encrenth

delirium of the dying is often of a most
interesting character, and resembles dreaming
more than any other form of derangement that
has fallen under our notice. The ideas are
derived less from present perceptions than in
insanity, and yet are more suggested by ex-
ternal circumstances than in the delirium of
fever and phrenitis. Thus the sight of a by-
stander often suggests the image of a friend
long departed, in which character the mori-
bund man addresses him, and talks earnestly
of persons, scenes, and events belonging to a
former period of his history as if still present.
The vivified conceptions are generally derived
from subjects which either in his speculative
pursuits, or in the business of life, have princi-
pally occupied his thoughts. The last words
of Dr. Armstrong were addressed to an ima-
ginary patient upon whom he was impressing
the necessity of attention to the state of the
digestive organs. We have heard that a great
legal officer not long deceased, having raised
himself for a moment from his couch, said
with his wonted dignity, “‘ Gentlemen of the
jury, you will find,”—and then fell back on his
pillow and expired. The visual conceptions
reproduced in some minds often appear to have
been derived from poetical reading. We re-
member hearing a young man, who had been
but little conversant with any but civic scenes,
discourse most eloquently a short time before
death, of “sylvan glen and bosky dell,” pur-
ling streams, and happy valleys ; “ babbling of
green fields,” as if his spirit had been already
recreating itself in the gardens of Elysium.
It not unfrequently happens that the spectra
owe their origin to contemplations of future
existence ; and consequently that the good man’s
last hours are cheered with beatific visions
and communion with heavenly visitors.

** Saw ye not even now a blessed troop
Invite me to a banquet, whose bright faces
Cast thousand beams upon me, like the sun?
They promised me eternal happiness,
And brought me garlands, Griffith, which I feel
I am not worthy yet to bear: I shall assuredly.”
King Henry VIII. Act iv. Sc. 2,

Dreadfully contrasted with such visions are
those which haunt the dying fancies of others.
The previous habits and conduct of the indi-
vidual have sometimes been such as to incline
spectators to. enquire whether in the mode of
his departure from existence he might not
already be receiving retribution; just as, in

799

other cases, celestial dreams and_ colloquies
have seemed fitting rewards for blameless lives
and religious meditation. It would be pre-
sumptuous, however, to hazard much upon the
final causes of the various modes of termina-
ting the career of life, not only for certain
obvious general reasons, but also because we
have known both the virtuous and the vicious
pass away in states of unconsciousness, to all
appearance precisely similar.

One of the most curious instances of de-
rangement that we have met with occurred in
a phthisical patient. It consisted in a morbid
association of ideas by mere similarity of ver-
bal sound, or in other words a propensity to
rhyme. Every person who came to the bed-
side was sure to receive a distich in honor of
his name; nor could any remark be made in
his presence without his seizing one of the
tile uttered and finding a rhyme for it, in
doing which he exhibited great ingenuity.
We were unable to ascertain whether he had
been addicted when in health to attempts at
metre. Recitations of poetry, appearing to recur
from a passive process of memory, with perfect
unconsciousness of what is passing around,
are frequent occurrences; and the passages
selected have often a singular coincidence with
events in the life of the moribund rehearser.
Sir W. Scott’s touching picture of the death
of Madge Wildfire has had many unfic-
titious counterparts.

Dementia or imbecility sometimes comes on
a short time before death. It is for the most
part manifested by an incapacity of concen-
trating the ideas upon any one subject, and by
an all but total failure of memory. The study
of the degree of this condition necessary for
invalidating a legal document is of great im-
portance to the medical jurist. The mental
weakness is in no respect so painfully exhi-
bited as in the facility with which the subject
of it derives pleasure from puerile amuse-
ments. “ Playing with flowers” is a token of
approaching dissolution enumerated by a dra-
matic author, one whose observation pervaded
human nature in all its phases. We remember
visiting a lady in the last stage of a uri-
nary disorder, during the progress of which
she had evinced both strength of mind and re-
finement of taste:—we found her arranging
with great care, and with demonstrations of
delight at her success, a garland of flowers
around a chamber utensil. A more humilia-
ting spectacle could scarcely be witnessed.
We augured that her decease was near athand,
and she died on the following day.

In the delirium under consideration, repro-
ductions of visual sensations bear a considera-
ble part; but in some cases the consciousness
is exclusively occupied by them ;—they are
mere ocular spectra. Thus with a vacant coun-
tenance, half-shut eyes, and gaping mouth,
and in a state of insensibility which no out-
ward impression can rouse, the victim of ty-
phus is seen catching at something in the air.
By the adjustment of the finger and thumb,
it is evident that the imaginary objects are
ofien minute; and it is not unlikely that they

800

produce a kind of ee ? like that of
musce volitantes, which the hand is instinc-
tively attempting to remove. Whether the

preduction of such spectra depends upon
changes in the retina, or upon changes in the

cerebral extremity of the optic nerve, is not

altogether certain; but we incline to the lat-
ter view, principally because other sensations
are often revived though the nerves in which
they originated have been paralysed or removed.

Renewals of perceptions of hearing are not
uncommon. Such are imaginary voices, and
sounds of tolling bells, &c.

No reason has been assigned for that sym-
ptom noted by the earliest observers—“ pick-
ing of the bed-clothes ;” or, in Dame Quickly’s

' phraseology, “ fumbling with the sheets.” But
we think it may be readily accounted for as
resulting from revivals of tactual sensations,
which produce corresponding movements, so
that the fingers grasp the bed-clothes in mis-
take for the imaginary substance. Something
analogous to this is witnessed in delirium
tremens, a disease in which visual conceptions
are particularly liable to vivifaction in the
form of animals, and in which also we have
witnessed the patient picking the ends of his
fingers as if to remove something disagreeably
adherent.

Whether consciousness of bodily sensations
continues till the very commencement of the
death-struggle, or agony,* as it is termed, is
an enquiry often put to the medical attendant
either by patients themselves, or by their anx-
ious relatives. The ideas entertained by per-
sons unaccustomed to physiological study re-
specting the pains of dying, have arisen partly
from their theoretical views of the nature of
the event itself, and partly from their obser-
vation of its preceding or accompanying phe-
nomena. When they imagined death to bea
kind of forcible severing of the spirit from the
body,—a separation so opposed to the incli-
nation of the former that some have fancied it
longing to return to the body,

——‘** iterumque ad tarda reverti
Corpora, que lucis miseris tam dira cupido:”

or like the shade of Hector,

Yogi Ox peléwr wrapévn "Aidic ds PeBaxes,
“Ov Titov yoowou, Armoio adeorira not nBny.
Iliad. XXII. 362.

‘or when they regarded the throes of death
as efforts of the confined inmate to escape
from its tenement; or when laying aside
their imaginings, they witnessed a heaving
respiration, cold dew on the face, and
convulsive agitations of the whole frame,
affections so often known to accompany in-
tense bodily suffering,—it is not wonderful
that the process of dying should have been
considered one of distress and anguish. But
the practitioner ought to be able to console

* The reader will scarcely need to be reminded
that this word is used in its etymological sense,
ayov, certamen, :

DEATH.

the friends of the dying by the assurance t
whatever may have been the previous te
it must be all over when once those char
begin in which death essentially consists. E
must explain to them how upon the failur
the circulation, the function of the brain’
cease by necessity ; that if the cessation ¢
former be gradual, that of the latter may ¢
often does precede it; that if the mortal pro-—
cess begins in the lungs, unconsciousness pre- _
cedes the arrest of the circulation; and if in —
the brain, that an injury of this organ sufficient —
to affect the lungs and the heart fatally is sure
to annihilate its own sensibility. The muscu- —
lar spasms, the slow, gasping, or gurgling —
breathing, the collapsed or distorted features,
though in some cases accompanied by feeling,
are altogether independent of it. Convulsion —
is not, as superficial observers often int

it, the sign of pain, or the result of an in-
stinctive effort of nature to get rid of the
cause of pain,—it is an affection of the moti-
fic not of the sensific part of the nervous sys-
tem.* The pangs of the disease may last till
within a short period of death, but it is a
great error to attribute them to the process
which brings them to an end. Such cases
however are rare; it is far more common for
the sensibility to be blunted, or for the cause
of pain to subside before the phenomena of
dying commence. A person poisoned by an —
irritant is said to die in great agony; a very
incorrect expression, since death in such cases

is ushered in by coma and by convulsions un-
attended with pain. ‘Temporary syncope and
asphyxia, the nearest approaches to actual
death, have nothing formidable in sensation if
we may judge from the reports of those who
have experienced them; so far from it indeed,
that some have described feelings of extreme
pleasure, connected with each of these con-—
ditions.

The relaxation and incapacity of the .
muscular system, though for the most part ex-
treme, has in some,cases been much less than
might have been expected; and even chronic
maladies, attended during their course with —
great emaciation and debility, have suddenly
terminated when the patients were in the act of
walking, or of performing some other exertion
disproportionate to the rest of the functions.
The condition of certain muscles in the last
stage of existence will be alluded to when we
come to speak of the general aspect and pos- ~
ture of the dying. oo

The voice is generally weak and low as —
death approaches, but sometimes has a shriller —
pitch than natural; sometimes it is husky and
thick, and not unfrequently it dwindles to a
mere whisper. These changes are caused prin=
cipally by the debility which the vocal share

* Dr. W. Philip has some excellent remark
upon this subject in his treatise on Sleep %
Death. . 1

+ See Principes de Physiologie Médicale, p
Isid. Bourdon, p. 319. [It was either Dr. E
or Dr. Cullen who told his attendant frienc
‘« he wished he could be at the trouble to te
how pleasant a thing it was to die.” ED.] —

DEATH. 2 801

with all the other muscles in the system. In-
terruptions of the voice are obviously often due
to the state of the respiration. It must not be
omitted that in some instances the voice has
remainéd firm to the last. .

Of the signs of death derived from the
organic functions, the first in importance are
those belonging to the circulation. The mode
in which the action of the heart declines is
extremely various, but has for the most part
some connexion with the nature of the dis-
order. In maladies of considerable duration,
and in which for a long time all the func-
tions have suffered in a greater or less degree,
the cessation of the heart’s motion is nearly
always gradual. The number of pulsations
may, within a brief period of decease, greatly
exceed the natural rate, but their energy is
impaired, and the quantity of blood expelled
at each systole is very small. In many
acute affections the failure is evidenced some-
times by increased frequency and diminished
vigour of the contractions, and sometimes by
their irregularity and frequency, the force being
but little altered. In such cases the cause of dis-
turbance is, without doubt, in some interruption
of the nervous connexions of the organ. In
other cases, the heart, before finally ceasing to
beat, contracts with great violence, and then
rapidly and suddenly comes to a stop. We
have frequently noticed this kind of action in
diseases of the brain, and have had reason to
think that the syncope was brought on by the
state of the respiration; the latter effect, how-
ever, being itself due in no slight measure to
the irregular action of the heart.

_ The increased frequency of the pulsations in
a debilitated state of the heart indicates.a greater
susceptibility to the stimulus of the blood, at
the same time that the resulting contractions
are less efficient. The period of repose be-
tween the diastole and the systole is briefer
than in the normal action, besides that less
time is occupied by the systole itself, in conse-
quence perhaps of the very slight shortening of
the fibres. In a vigorous heart the reverse of

this takes place; the irritability is not such as

to prevent a considerable pause after the dias-
tole, and the fibres undergo a much greater
degree of shortening. Why the irritability of
a part should increase toa certain extent with
increasing debility, is a problem yet to be
solved. But we have reason to think that it is
chiefly in acute diseases that the great rapidity
of the heart’s action is presented, and that in
chronic affections there is a more gradual ex-
haustion of irritability. Inequality of arte-
rial action, when amounting to a great degree,
is one of the most threatening symptoms that
can be witnessed. We allude particularly to
that extraordinary pulsation. of the carotids
which is sometimes observable, when the ra-
dial artery can scarcely be distinguished. It is
perhaps one of the strongest presumptions
that arteries possess a vital contractility, which
may be disturbed in them as in other parts of
the system.

The state of the respiration in a moribund
person is extremely various; sometimes hur-

ried and panting till within a few moments of
decease; sometimes ceasing gradually, in har-
mony with the languishing circulation; but
sometimes slow, laborious, and _ stertorous,
and, as Haller expresses it, “ dum anxietas
equidem cogit moliri, vetat debilitas.”* In
addition to those causes of struggling respira-
tion which belong to the nervous centres and
to the circulation in the lungs, the function is
often dreadfully embarrassed by the accumu-
lation of fluids, mucous, serous, or purulent,
in the bronchie. The quantity of these secre-
tions is often increased by a state of the bron-
chial membrane, analogous to what we shall
notice presently in the skin, designated by
Laennec “ the catarrh of the dying;” but the
mere accumulation of the natural quantity
from defect of those muscular actions which
usually remove it, whether in the fibres of
Reisseissen, or in the general respiratory appa-
ratus, is amply sufficient to cause exquisite
distress. Mediate or immediate auscultation
detects a loud guggling throughout the chest,
which is sometimes audible even at a little
distance, and the vibrations of which may be
felt by the hand. This sound must not be
confounded with the true“ death-rattle,” which
is produced not by struggles between air and
liquid in the bronchial ramifications, but by
the ejection of air from the lungs through the
fluid in the trachea. It is often followed by
a flow of spumous liquid through the mouth
and nostrils.

The loss of animal heat occurs first in the
extremities,—a fact easily explicable by the
smaller quantity of blood sent into them; but
it is probable that the state of the nervous
system, and the cessation of the nutritive and
other capillary actions, which perform so im-
portant a part in calorification, may participate
in the production of the result in question.
The recession of heat from the limbs was no-
ticed by Hippocrates, but his mode of stating
the fact in one remarkable passage, his last
aphorism, appears considerably affected by his
theoretical views of the use of this agent in
the economy.t

The secretions present nothing very charac-
teristic. If the disorder has been of short
duration, they may have undergone no consi-
derable change; but when the declension of
life has been more gradual, they are all more
or less altered. The bile and the urine are
often found in their proper receptacles, of a
perfectly healthy character, after a short illness ;
while in senile dissolution they are almost
always scanty and vitiated. The generation of
gas in large quantities, so as to produce tym-
panites, is a very common occurrence at the
termination of acute diseases.{ We have also
noticed loud borborygmi during the last few
hours of life, occasioned by large collections
of air, and by a preternatural excitement of
intestinal irritability, analogous to what we
have noticed in the heart and arteries. The

* Elementa Physiologia, lib. xxx. § 22.
+ Hippocr. Aph. § viii. 18.
¢ Hipp. Aph. §-viii. 17.

802

secretion of saliva is almost always suppressed,
and the mucus about the mouth and_ nasal
passages is so deficient, that the lips and
tongue require constant moistening when arti-
culation is attempted; not to mention the inex-
tinguishable thirst which is one of the most
painful forerunners of some forms of dissolu-
tion. The perspirable secretions are generally
rather profuse than scanty. The cutaneous
surface, particularly about the face, is bedewed
with a clammy exudation. It cannot be said
that the weakness of the circulation is the
immediate cause of this circumstance, because
it frequently happens ina very opposite state
of the function. It is true that the latter fact
has been explained by supposing a transuda-
tion of the thinner part of the blood through the
coats of the capillary vessels during their disten-
tion, while the former has been attributed to a
spasm of the same vessels, consequent on the
diminished force of the circulation, and said
to have the effect of squeezing out the same
serous liquid. In each case we must presume
the perspired fluid to be in a state of separa-
tion before the supposed agency can come into
operation. The hypothesis is supported by
little evidence ; but we are not sure that any
other interpretation can be found much more
conclusive. It seems probable, however, that
the fact in question results less from so mecha-
nical a process as has been hinted at, than
from a chemical alteration in the fluids, in-
duced perhaps by a change of innervation, in a
manner analogous to those extraordinary
changes which the secretions so frequently pre-
sent under the influence of mental emotion.

It remains for us to enumerate a few of the
signs of approaching dissolution, derived from
the general aspect of the body. Many of
these have been described by Hippocrates with
unrivalled accuracy. The sunken eyes, the
hollow temples, the sharpened nose, the fore-
head dry, tense, and harsh, the complexion
sallow, livid, or black, the lips cold, flaccid,
and pale, or of a leaden hue—compose the
celebrated fucies Hippocratica.* All these signs
admit of an easy rationale by the state of the
circulation and of the muscular system. They
are however in some measure due to the con-
dition of the cellular tissue, which, indepen-
dently of its loss of fat, is exhausted of that
interstitial fluid, which in health contributes so
much to the firmness and equality of the cu-
taneous surface. In proof of this we may men-
tion that all the appearances enumerated may
be produced merely by a violent illness of a
few hours; by cholera for instance, a disease
in which the serous fluid is rapidly drained
from the system into one channel. Excessive
fatigue and fasting will occasion appearances
very similar, and therefore the Father of Medi-
cine recommends us to ascertain whether such
causes have been in action, before we pro-
nounce the patient to be moribund. A partial
closure of the eyelids:and a gaping mouth

* These signs are not thus grouped together in
the original, but are individually mentioned in the
book ‘* Mpoyvwerrinov,” not the “ TMeps voicwy,””

DEATH.

are signs, when conjoined with the others, of
fearful import. There must be an extreme
depression of the nervous system when the
orbicularis is unable to bring the lower lid into
contact with the upper, which has drooped
from relaxation of the levator palpebre, and
when the masseter and temporal muscles resign _
the lower jaw to gravitation. A supine posi-
tion with fe limbs extended, and a tendency

to slide down to the lower part of the bed, are
indications of mortal prostration. In the pos-
ture alluded to there is little or no muscular
exertion; for the extension of the legs, when
the body lies upon the back, is not necessarily
maintained by the action of the extensor mus-
cles, since the mere support of the surface on
which they rest would keep them in that posi-
tion. The sliding down in the bed is owing to
the inability of the gluteal muscles to resist
the gravitation of the trunk down the inclined
plane, upon which this part of the body is
extended when the head and shoulders are
resting upon the pillow. When the prostration
is less extreme, it often happens that instead of
the extremities being carried forward by the
impulse alluded to, the thighs are raised, the
knees bent, the soles rest flat upon the bed,
and the heels afford a sufficient resistance to
the nates to prevent any further descent. It is
evident that this position of the legs and thighs,
though requiring a muscular effort for its pro-
duction, needs little or none for its mainte-
nance.

The moribund are often impatient of any
kind of covering. They throw off the bed-
clothes, and lie with the chest bare, the arms
abroad, and the neck as much exposed as
possible. These actions we believe to be
prompted by instinct, in order that neither
covering” nor even contact with the rest of the
body may prevent-the operation of the air
upon the skin. There are actions and re-ac-
tions between the air and the blood in the
skin, similar to those which occur in the
lungs, and hence in asphyxial disorders the
symptoms alluded to are very marked; but
the mere influence of the air upon the cuta-
neous nerves has been proved by Dr. Edwards
to be beneficial to the vital powers. Certain it
is that these symptoms are sometimes prominent
in cases where the respiration is very little in-
volved in the mortal struggle. Orfila, im one
of his cases of poisoning by sulphuric acid,
mentions that the subject of it made con-
stant efforts to remove even the lightest kind
of covering.

The appearance of the face is by no means
such as we have described it above, in all cases.
The kind of death must always havea great
influence on the expression. On fields of
battle the corpses of those who died of stabs
are easily distinguished by the countenance, —
from those who fell by gun-shot. In the for-_
mer an extremely painful impression must
have been transmitted to the brain, which pro-
duced the usual change in the nerves and —
muscles of expression; in the latter a con-
cussion was given to the whole system, para-_
lysing without any intermediate sensation, so _

be

= = ial _

S <6 ee Pe ae eee

—

AF

PEEPS PET SP er ae ae ee

DEATH. 803

that no expression remained more than that of
the repose of the muscles. The nature of the
disease also modifies the facial expression of
the dying. In some we observe the impress
of the previous suffering, as in peritonitis and
in cases of poisoning by irritants; in others
the character is derived from a peculiar affec-
tion of some part of the respiratory apparatus,
as of the diaphragm in pericarditis; or from
an affection of the facial muscles themselves,
as in tetanus and paralysis. But the condition
of the mind is perhaps more often concerned
in the expression than even the physical cir-
cumstances of the body. For, as some kind
of intelligence is frequently retained, and
strong emotions are experienced till within a
few moments of dissolution, the features may
be sealed by the hand of death in the last look
of rapture or of misery—of benignity or of
anger. Every poetical reader knows the pic-
ture of the traits of death (no less true than
beautiful) drawn by the author of the “Giaour.”
But such observations are not confined to
poets. Haller could trace in the dying coun-
tenance the smile which had been lighted by
the hope of a happier existence: “ Adful-
— Sugienti anime spei non rard in mori-
undis signa vidi, qui serenissimo vultu, non
sine blando subrisu, de vité excesserunt.” *
Watchers of the dead have often affirmed, and
we can ourselves testify to the fact, that a

smile has appeared upon the countenance some.

hours after death, though no such expression
had been witnessed at the time of the event ;
which is not difficult of interpretation if we
consider that an extremely slight muscular
action is sufficient to give any kind of expres-
sion, particularly that of complacency,—that
mortal rigidity is produced by a species of
contraction in muscular fibres, (to be discussed
more fully hereafter), and that this change
seldom takes place till several hours after
death.
SIGNS OF ACTUAL DEATH.

The discrimination of true from apparent
death is not a matter of mere physiological
interest. It is of great importance that the
medical practitioner should be able to decide
in doubtful cases whether the resources of art
may be dispensed with, or the rites of sepul-
ture be permitted, as well as to give evidence,
in certain medico-legal inquiries, of the pre-
cise period at which an individual expired.
We have not space to record the numerous
cases that may be met with in various authors,
proving that even the most sagacious and ex-
perienced observers have been at times de-
ceived as to the reality of death. In the works
of the ancients there are frequent allusions to
premature interments. Pliny has a chapter,
* De his qui elati revixerunt;” and among
other cases mentions that of a young man of
rank, who was revived by the heat of his
funeral pyre, but who perished before he could
be rescued from the flames. ‘“ Hee est con-
ditio mortalium,” is the reflection of the phi-
losopher, “ ad hasce ejusmodi occasiones for-

* Blem, Phys. lib. xxx. § 23.

tune gignimur, ut de homine ne morti quidem

debeat credi.” Celsus asks, “ si certa future

mortis indicia sunt, quomodo interdum de-

serti a medicis convalescant, quosdamque

fama prodiderit in ipsis funeribus revixisse ? ”

“ Complura fuerunt exempla,” says Lord

Bacon, “ hominum, tanquam mortuorum aut

expositorum a lecto, aut delatorum ad funus,

quinetiam nonnullorum in terra conditorum, -
qui nihilominus revixerunt.”*

In the writings of Winslow} and Bruhier f
will be found an ample collection of melan-
choly instances of premature interment, besides
those which are scattered through various sys-
tematic works upon forensic medicine. Un-
intentional vivisection, moreover, has befallen
other instances than the celebrated subject
of Vesalius. Few of our readers have not
shuddered at the tale of the dismal fate of
the Abbé Prevost, who, having been struck
with apoplexy in the forest of Chantilly, was
taken home for dead, but recovered his con-
sciousness under the scalpel, and died im-
mediately afterwards.. We must not recount
the marvellous recoveries recorded by French
authors, of Madame Mervache, the wife of a
jeweller at Poitiers, who was restored to life
in her grave, by the attempts of a robber to
despoil her of the rings with which she had
been buried; and of Francois Civille, a Nor-
man gentleman, whose custom it was to add
to the signature of his name, “ trois fois mort,
trois fois enterré, et trois fois par la grace de
Dieu ressuscité.” The English reader will
find an interesting selection of cases in the
Appendix to Dr. Smith’s Principles of Fo-
rensic Medicine, and in the article Premature
Interments in the Encyclopedia Britannica.
We shall only add that Bruhier collected fifty-
two cases of persons buried alive, four of per-
sons dissected prematurely, fifty-three of per-
sons who recovered without assistance after
they were laid in their coffins, and seventy-two
falsely reported dead.§

We shall arrange the indications of death
under three heads :—

1st. Signs of the extinction of vital functions
and properties.

2dly. Changes in the tissues.

3dly. Changes in the external appearance of
the body.

1. The arrest of the circulation and respi-
ration would at first appear to afford decisive
evidence that a person is no longer alive. But
this sign is liable to the two-fold objection that
we cannot distinguish with absolute certainty
the minimum of the functions mentioned,
from their complete annihilation, and that re-
coveries have taken place after their real or

* Hist. Vite et Mortis, § x.

+ Dissert. an mortis incerta sint indicia.

t Dissert. sur l’Incertitude des signes de la mort.

§ Louis in his Lettres sur la Certitude des signes
de la mort, insinuates that some of Bruhier’s cases
are apocryphal. A more recent and perhaps a
more authentic collection of cases will be found in
M. Julia de Fontenelle’s <‘ Recherches médico-
légales sur l’incertitude des signes de la mort,” &c.

1834,

804

> sob cessation. The case of Colonel
‘ownshend, related by Cheyne,* is too well
known to need recital here. Perhaps the most
unequivocal examples of their suspension are
certain cases on record of restoration after sub-
mersion for several minutes. In some of these
there is good reason to believe that there was
no genuine asphyxia, but that syncope took
place immediately, and consequently that there
was no stagnation of blood in the extremities
of the worst arteries. As to the alleged
cases of persons who have been said to lie
many hours and even days without pulse or
breathing, we do not hesitate to express a
belief that the observers were deceived, and
that in reality both these functions were per-
formed, but in so low a degree as to escape
detection, just as hybernating animals were
supposed to be, during their torpor, in the pre-
dicament alluded. to, until the researches of
Dr. M. Hall proved that these animals do
actually respire and maintain their circulation,
though in a much less degree than when
awake. It will be the duty of the practitioner
to adopt every method within his reach of
ascertaining the actual condition of these func-
tions; but he must remember that they are
often inefficient and even fallacious. Thus,
with regard to the common modes of trying
the respiration by a mirror, or by light downy
bodies placed near the mouth and nostrils,
it is obvious that the former may retain its
clearness, because the halitus is not in suf-
ficient quantity to stain it, or may be dimmed
by exhalations from the air-passages which are
not the products of respiration; and that the
downy substances may be stirred by currents
of air, or remain unmoved by the trivial ex-
change which takes place between the external
atmosphere and the air in the chest of the
person examined. Winslow’s test of a vessel
full of water placed on the lowest part of the
thorax is of little utility, since we know that
the diaphragm may be the only muscle em-
ployed in expanding the chest. As to the
circulation, it may continue though no pul-
sation can be felt over the arteries or the car-
diac region, and no sound be perceptible by
auscultation mediate or immediate. Few prac-
titioners would be willing to apply M. Fou-
bert’s test, to wit, that of making an incision
in One of the intercostal spaces, and feeling
the heart with the finger!

The loss of irritability in the muscular fibres
is of far greater consequence than either of the
foregoing signs. It may be present when re-
covery is out of the question, but its absence
is quite conclusive. Galvanism affords a cer-
tain and ready method of detecting this pro-
perty. According to the researches of Nystent
uritability is first extinguished in the left ven-
tricle ; after forty-five minutes it has left the
intestines and stomach ; a little later the blad-
der; after an hour the right ventricle; after an
hour and a half the cesophagus; after an hour

* English Malady, page 307.
t Recherches de Physiologie et de Chimie Pa-
thologique. ih

DEATH.

and three quarters the iris. It next takes leave
of the muscles of the trunk, then the lower
and upper extremities, and the right =
auricle. The duration of contractility is short-
ened by a warm and humid state of the at-
mosphere, by ammoniacal gas, carbonic acid,
and sulphuretted hydrogen. It is unaffected by
carburetted hydrogen, chlorine, and sulphur-
ous acid; nor is it found diminished in cases
of asphyxia by strangulation and immersion.
The annihilation of that particular kind of
contractility of tissue, which is equally dis-
tinct from muscular contractility, irritability,
and elasticity, is one of the surest signs of
death. We see it wanting in the collapsed
edges of a wound which has been inflicted on
the skin of a dead body, as contrasted with
the gaping appearance of a similar lesion made
during life.

The loss of animal heat, though an invariable
occurrence at some period after death, is not
unfrequently noticed in disease. Every prac-
titioner must have met with it in hysterical
cases; and it is a matter of notorious obser-
vation in cholera. On the other hand we have
known the heat of the body not only continue
but even return at a considerable period after
death has unequivocally taken place; a fact
attributable either to chemical actions of a
cadaveric description, or to the continuance of
the processes which developed calorie during
life. The mean time requisite for the com-
plete cooling of the body is fifteen or twenty
hours; but the process is modified by a great
variety of circumstances. It is slower after
acute than chronic maladies, but is very con-
siderably retarded in. asphyxial cases, except
those occasioned by submersion.

Calorification is not the only function that
may survive what is commonly called death ;
thus the rectum and bladder have been known
very frequently to discharge their contents
after death ; and, which is still more remark-
able, parturition has taken place under such
circumstances. The continuance of secretion,
absorption, and nutrition has been argued
from the exhalation of serous fluids in some
parts, their disappearance in others, and the
alleged growth of hair. Some of these facts
are more rationally explained on such physical
principles as are involved in transudation,
endosmose, penetration, &c. &c.; as to the
growth of hair, there is great reason to doubt
the accuracy of the testimonies to the fact.
Haller very justly observes that shrinking of
the skin would produce an apparent elongation
of the beard, which is the part upon which
the observation alluded to has been most fre-
quently made. ; .

2. The first alterations in the physical pro-
perties of the solids after death are softness
and flexibility, to which succeed sooner or later
the opposite conditions of firmness and rigi-
dity. The softness or want of elasticity may —

-

be owing partly to differences in the distri-
bution of the fluids in the tissues, and partly —
to changes in the tissue itself. The flattening
of those upon which the weight of the
body rests, the effect of deficient elasticity,

SES ep Pa ee Le eee eee

‘
:
:
,

tT

~

DEATH.

is considered by Blumenbach a valuable cri-
terion of the reality of death. The flexibility
of the joints obviously depends upon the re-
laxation of the muscles.

Rigidity is a change which has attracted
great attention from its importance as an evi-
dence of death. Its period of accession de-
pends principally upon the nature of the ma-
lady. After long and exhausting illnesses,
its appearance is early, but the duration is brief,
and the intensity trifling. The same remark
sppuee to the modifying influence of old age.

hen the individual has been cut off by sud-
den accidental causes or by acute diseases,
it comes on for the most part much later,*
lasts longer, and is more intense than in the
former instances. It may appear within half
an hour after death or may be delayed twenty
or thirty hours, according to the circumstances
just mentioned. The mean duration is from
twenty-four to thirty-six hours; but it may
last six or seven days according to Nysten,
whose researches upon this subject are very
valuable. We remember observing it once on
the eighth day after death in the body of a
criminal who had been executed by hanging,
but are not aware at what time it had com-
menced. The parts which first present this
change are the neck and trunk; it then appears
in the lower extremities, and lastly in the
upper. Its departure observes the same order.

_ It is yet to be proved that rigidity is not an
invariable consequence of death. .Nysten at-
tributes Bichat’s assertion of its non-appear-
ance in some cases of asphyxia, to the lateness
of its developement. If it could be wanting
in any case, it would probably be so in sub-
jects attenuated and of flabby fibre. Louis in
his Letters on the Certainty of the Signs of Death
declares that he never found it absent even in
the infirm and age-worn patients of Salpetriére,
and Foderé gives a similar testimony to its
universality .>

The seat of rigidity is the muscular sub-
stance. _Of this we may be assured by the
following facts. (1). It is observed in all those
animals (including many of the invertebrata)
which have a distinct muscular tissue. (2). Its
intensity is in a direct ratio with the develope-
ment of this tissue. (3). It is destroyed by
division of the muscles, a fact first noticed by
Nysten.{ (4). It remains when the cellular
membrane, skin, aponeurosis, and ligaments
are removed.§ (5). When very strong, it ren-
ders the muscles prominent as in voluntary
contraction, or in that spasm which is induced
by rammollissement of the brain and spinal
marrow. Ch. Louis makes a remark of this
kind in his admirable memoir upon some cases
of sudden death.||

In hemiplegiac subjects rigidity is observed

* We very recently however observed the phe-
nomenon only an hour and a half after the death
of a boy by acute peritonitis.

+ Méd. Lég, t. ii. p. 361.

t Rech. de Physiol, et Pathol. Chim.

§ Devergie, Dict. de Méd. et Chir. Prat, Art.
Mort.

|| Rech. Anat, Path. p.500.

805
to be no less strong in the paralysed limbs
than in those which were unaffected by the
disease. ‘The temperature of the body has been
said to influence it. Beclard* speaks of cooling
as being always antecedent to rigidity, and
Nysten has made a similar statement. But we
have had many opportunities of disproving this
observation. Ch. Louis noticed the pheno-
menon in some of the cases just adverted to,
while the bodies were quite warm. Its occur-
rence in cold-blooded animals is, we think, a
sufficient refutation of the idea that it bears
any necessary relation with the loss of heat.
Moreover Devergie has very properly pointed
out the inconsistency of this notion with the
fact that rigidity appears first upon the trunk,
the region which is the last to be deserted by
caloric.

The cause of rigidity is referred by most
authors to a sort of lingering vital contraction.
It is often spoken of as the last effort of life:
“11 semble que la vie,” says Nysten, “se
réfugie en dernier lieu dans ces organes, et
y détermine le spasme qui constitue le roi-
deur.” + This author not only refers it to con-
traction, but endeavours to explain how a very
low degree of the ordinary kind of contraction
may be sufficient to stiffen the muscles though
not to move the part with which they are con-
nected. Supposing that a muscular effort equal
to 20 would completely bend the elbow, one
equal to 10 would semiflex it; one equal to
5 would bend it a quarter of the distance;
while aforce equal to 1-20th only, would perhaps
produce no motion at all, nothing but rigidity !
Beclard alleges three causes; the last contrac-
tion of muscular fibres, the general cooling of
the body, and the coagulation of the fluids.
The second of these we have already disposed
of. Notwithstanding the high authorities in
favour of the opinion that rigidity is caused
by a vital contraction, we confess that to us it
appears a very untenable position. All mus-
cular contraction in its normal condition alter-
nates with relaxation; and although rigidity
might be supposed to bear some analogy to
the tonic spasm of tetanus, it differs widely
from the latter in one important respect, that
when overcome by violence it does not return.
When we consider that the continuance of
the phenomenon in question is long after
the cessation of any vital action; that the
usual time of its accession is precisely that
which we have every reason to consider the
most unfavourable for the occurrence of any
vital action, viz. when all animal heat is ex-
tinct, and when sanguineous congestions in the
depending parts of the body prove the capil-
laries to have lost their contractility; it is diffi-
cult to regard the process as of a vital cha-
racter. The mere fact that the rigidity comes
on and remains long after the muscles have
ceased to respond to the stimulus of galvanism,
reduces the hypothesis to the last degree of
improbability. Moreover we should scarcely
expect the last act of life to be performed in

* Anatomie Générale, p. 127.
+ Op. cit. Gv. art. 3, —

806
the extremities; we should naturally look for
it about the trunk, in conformity with the order
of disappearance observed by all other vital
actions; but as we have stated above, this phe-
nomenon both appears and declines first upon
the trunk; in other words, according to the
hypothesis, the muscles in this part expire
while those of the extremities are still alive.
Devergie is puzzled to reconcile the long
continuance and intensity of rigidity in cases
of asphyxia from carbonic acid, with the
fact that this agent is destructive to contrac-
tility. We are somewhat surprised that he
was not brought, by the mutual opposition of
these facts, to consider that rigidity and vital
contraction have nothing in common but the
tissue in which they are manifested.

The third cause enumerated by Beclard is
the coagulation of the blood. This is probably
nearer the truth than are the other explanations
of the phenomenon ; but it would be more
correct to say that rigidity and coagulation of
the blood are effects of the same causes, viz.
coagulation of fibrin. They occur about the
same time, and are impeded by the same
agents. It has been proved that the muscles
are the subjects of the rigidity, that they are
contracted, and that their contraction is not of
a vital nature. As this change must there-
fore be either mechanical or chemical, what
more probable cause (in the absence of actual
demonstration) can be imagined than the coa-
gulation of fibrin in the muscles?

The rigidity occasioned by certain diseases
may be mistaken by an unpractised observer
for mortal stiffness. This error is most likely
to be committed in cases of hysteria, for this
affection, not content with imitating almost
every other malady, has been often successful
in mimicking death itself. Tetanus is in-
stanced by some authors as a disease likely to
occasion mistakes of the kind alluded to. This
may be true of hysteric tetanus, but not of the
idiopathic or of the traumatic species, which
have characters too striking to be overlooked
by even the most inexperienced. Besides, if
the rigidity of any given case, supposed by one
to be cadaveric, were by another proved to be
tetanic, we are of opinion that the condition of
the subject would be not a whit less hopeless,
since the case implies that the respiration and
circulation are apparently extinct; and when
this is the case in tetanus, we may feel
quite certain that if the patient is not actually
dead, he is quite irrecoverable. Nysten de-
clares that the rigid spasm of disease may
be always distinguished from that of death by
the circumstance that it precedes the loss of
heat in the former case, while in the latter the
order of the events is just the reverse. This
test holds good in a very large proportion of
cases, but must not be implicitly relied upon,
because, as we have before observed, corpses
not unfrequeutly retain their caloric for some
time after rigidity has commenced. A better
criterion is that of overcoming the rigidity
by force; if it be cadaveric, the contraction
is completely annihilated; if morbid, it will
return when the force is withdrawn.

DEATH.

‘A species of rigidity more likely to be con-
founded with the cadaveric is that which is
sometimes found in the dead body, but which
is the product of disease. Of this description
is the spasmodic contraction which often con-
tinues after death by apoplexy and other cere- }
bral and spinal diseases; and the observation =
of which is as old as the time of Hippocrates. ;
M. Marc relates the case of a gentleman who
went to a theatre apparently in good health,
and after the representation was over, was
found by his friends sitting in the front of the ;
box, with his head resting upon his hands, and
his elbows on the ledge. He had died of apo-
plexy, and been retained in that position by
the tonic spasm of his muscles.* This con-
traction is unquestionably vital, but it ceases
after a few hours, and the flexibility is then
succeeded by true cadaveric rigidity. In
medico-legal cases it is of the utmost moment ;
to bear this distinction in mind, but it is one |
that has received much too little attention.
Many of the standard works upon forensic
medicine are altogether silent upon the subject.
Its importance was proved by a case which
occurred in France some years ago. The body
of a man named Courbon was found in a ditch,
with the trunk and limbs in such a relative
position as could only have been maintained
by the stiffness of the articulations. This
stiffmess, moreover, must have come on at
the very time when the body took the said
position, unless it could be imagined that the
body had been supported by the alleged mur-
derers until the joints were locked by cada-
veric stiffness, a supposition infinitely too im-
probable to be entertained for an instant. But
by regarding the rigidity as of a spasmodic
nature (resulting from apoplexy, of which there
were sufficient proofs in the necroscopy), the
difficulties of the case were altogether removed.
A full report of the case, and of the medico-
legal consultation upon it, will be found in the
seventh volume of the Annales d’ Hygiene. In
death by asphyxia there is often a spasmodic
contraction which may continue for some time
after decease. Orfila+ is of opinion that this
may be readily distinguished by the continu-
ance of animal heat, which he agrees with
Nysten in judging to be incompatible with
rigidity. While denying the universality of
this principle, we think it sufficiently extensive
to admit of a very useful application in a great
number of instances.

From what has been said, it can scarcely
be doubted that rigidity is a certain evidence —
of death. Prior to this there is no indication
derivable from changes in the tissues which
can be depended upon; but the flexibility that
follows it affords, if possible, still stronger
proof of the condition of the body. There is
no state with which it can be confounded if
we except the interval between spasmodic and
true post-mortem stiffness; but very little cau-
tion is requisite for avoiding a fallacy of this
description. , ;

* Annales d’ Hygiéne, &c. t.vii. p. 604.
+ Lecons de Méd. Lég. t. ii. p. 195.

DEATH.

The next remarkable change which takes
lace in the tissues is putrefaction, a process
in which the ultimate elements of the body,
operated upon by external causes, enter into
combinations incompatible with the existence
of those proximate principles of which the tex-
tural molecules are compounded. Some phy-
siologists conceive that even putrefaction is
not a necessary sign of death. Winslow,
however, pronounces it “unicum signum;”
and Bruhier expresses a similar opinion. Hal-
ler* says that it may commence in a living
person, but that death must be very near at

hand. He relates of one Vandenhoeck, his

bookseller, that when lying in the last stage of
a malignant fever, he prophesied his approach-
ing end, and that he grounded his prediction
upon his sense of smell. Orfila, one of the
greatest authorities upon this subject, considers
the commencement of putrefaction a less un-
equivocal sign than true rigidity ; his opinion
rests upon the fact that he has known persons
completely recovered, notwithtsanding the skin
was covered with violet spots, which exhaled
an infectious odour.t It is remarkable that so
acute an observer should have overlooked
what seems a very obvious consideration, viz.
that these violet spots being caused by extra-
vasated blood, perhaps in a state of decom-

sition, afford no Sehieative that putrefaction
has begun in the solids. Sphacelus, though
consisting in decomposition, need not be con-
founded with putrefaction. The latter change
begins always, according to the observation of
M. Devergie, either upon the abdomen or the
thorax, and has the appearance of a large
diffused patch of a green colour, which after-
‘wards becomes brown. The brown portion is
surrounded by a green areola indicating the
extension of the process. Into the history of
putrefaction we cannot enter, but must refer to
the valuable “ Exhumations Juridiques” of
MM. Orfila and Lesueur, and to some papers
‘by M. Devergie in the second volume of the
Ann. d’Hygiéne on the changes in the bodies
of persons drowned, and also to a controversy
upon the latter subject between this author and

. Orfila, in the fifth and sixth volumes of the
same work.}

After the decomposition has advanced toa
certain stage, but sometimes without any putre-
faction at all, the tissues, instead of being dissi-
pated by conversion into liquid and gaseous
substances, which is the essential part of the
‘putrefactive process, may be converted into
solid matters widely differing from the original
molecules. (See Aprpocere and Mummi-
FACTION.)

3. We have lastly to notice a few signs of
the reality of death gathered from the external
aspect of the body. ‘The appearance of the
face has been already described among the
signs of the moribund state. We have only
to mention in addition, that instead of the

* Op. et loc. citat.

t Op. cit. t. ii. p. 231.

t Devergie’s papers are embodied together with
more recent observations in the first volume of his
«‘ Médecine Légale,” published a few months ago.

807

paleness or lividity that were present at the
time of death, a rosy hue may appear upon
the cheeks, which has not unfrequently occa-
sioned a deceitful hope that life was not yet
extinct. The cause was very rationally as-
cribed by Mr. Chevalier to the action of at-
mospheric air upon the blood accumulated in
the capillaries. This phenomenon is more
likely to occur when syncope has followed
asphyxia. We remember it once very dis-
tinctly in a person who had died of acute
hepatitis, but in whose last hours there had
been considerable pulmonary congestion; it
made its appearance on the third day after
death. The state of the eyes has been much
insisted upon by some; particularly their dul-
ness, the shrinking of the cornea* from the
diminution of the aqueous humour, and the
viscid mucous secretion which forms what is
called the film of death; but these appearances
may be absent in real death, and present be-
fore life has terminated. Thus the eye is often
prominent and glittering after death by carbonic
acid, and by hydrocyanic acid.

The iris is generally represented to be ina
state of dilatation. Winslow} paid conside-
rable attention to it, and states that he gene-
rally found the pupil of a moderate size, often
much contracted but never much dilated.
Whytt{ makes the same observation. The
fact appears to differ with different animals.
Thus in the cat and pigeon the pupil dilates
after death, while in the rabbit it contracts.§
Our own observations upon the human sub-
ject incline us to report the pupil a few hours
after death as in a state midway between con-
traction and dilatation. It is difficult to speak
with precision upon the point, because that
which would be relative contraction in the
pupil of one person would be dilatation in
another, and vice vers. We have known ob-
servers confound immobility with dilatation,
and to this circumstance we attribute the
common statement that the pupil is dilated
at and after death. It is evident that if we
admit that the contraction and dilatation de-
pend upon predominant action of the lon-
gitudinal or of the circular fibres, we ought
to expect in the death of the part neither the
one condition nor the other; but as the con-
tractility of this as of other muscular parts
may survive the cessation of the central func-
tions, either set of fibres may prevail for a
time. It must be remembered however that con-
traction of the iris may depend upon a cause
altogether different from contraction of its
fibres, viz. congestion of blood in its tissue,
which is said to have some analogy to the
erectile. M. Renard states that in some ex-
periments upon dead bodies instituted for the
purpose of ascertaining the effects of com-
pression of the diaphragm upwards by the
development of gas in the abdomen, found

* Louis fancied that this sign was invariable.
t Op. cit. ;
¢ On the Vital and other Involuntary Motions of
Animals, p- 129. ‘
A Mayo’s Outlines of Physiology, p. 292, 3d
edit.

808,
that it occasioned “ refoulement vers la téte
de la portion fluide du sang qui est contenu
dans Voreillette droite, et par suite, réplétion,
tuméfaction des veines du cou, de la face,
de l’encéphale, suintement, exsudation séreuse
ou sanguinolente par les porosités, les extré-
mités des réseaux capillaires; quelquefois
aussi, par suite de ce reflux dans les réseaux
capillaires, resserrement de la pupille, réplé-
tion, distension, saillie des yeux, qui étaient
d’ abord ternes et relAchés, &e. &c.”* .

M. Villermé+ has described an appearance
of the hand which he considers characteristic
of death. He says that when dissolution has
taken place the fingers are brought together
and slightly bent, but that the thumb is co-
vered by them, being always found in the
hollow of the hand directed towards the root
of the little finger. The phalanges of. the
thumb are extended upon one another, but
the first is flexed upon the metacarpal bone.
Villermé states that he had often noticed this
appearance in dead bodies on fields of battle
and in hospitals, but that he had never at-
tached any importance to it as a sign of death,
till his attention was directed to its value by
M. Breschet. We have often confirmed the
truth of Villermé’s description by our own
observations, particularly in hospital cases,
before the bodies have been subjected to the
straightening processes of the attendants upon
the dead. When the appearance has been
wanting, we have had reason to suspect that it
had been removed by force.

The last sign to be spoken of is the altered
colour of the surface, presenting lividities of
various extent. They may occur in spots or in
circumscribed patches, but more frequently
they take the form of an irregular suffusion of
a pale violet, or a dull reddish hue. They
always occupy the depending parts, and are
most intense where the skin hangs loose, as in
the scrotum, the penis, and the labia. They
have also a direct ratio with the suddenness
of the death, the quantity of blood in the
system, and its tendency to continue fluid.
Their presence indicates that gravitation has
either subdued the capillary forces, or has come
into play after the cessation of the latter.. But
they may occur during life. We have often
noticed that the livor of the skin in bronchitic
affections is more intense in the back and
the sides, and is even confined to these parts.
There can be no doubt that congestions in the
parenchyma of the lungs are often dependent
upon position. The questions that arise out
of these appearances have more to do with the
cause of death than with the reality of this
occurrence. When circumscribed, they may be
confounded with ecchymoses resulting from
violence. To enter upon the discrimination of
these conditions would engage us in a dis-
cussion far too lengthened for this article,
which has already exceeded its limits; we

a Ansett sia azhe sur |’?Ouverture des Cadavres,
p- °
+ Ann. d’Hyg, t. iv. p. 420.

DEATH.

must content ourselves with referring to me-
dico-legal treatises and to an extremely valu-
able paper by Dr. Christison in the Edinburgh

Medical and Surgical Journal.*

We shall conclude with a brief abstract of
M. Devergie’s observations upon the know-
ledge which we may collect from the state of
the body respecting the time which has elapsed
since death. a

We may suspect that the body has been _
dead from two to twenty hours if there be
flexibility, elasticity, heat, and contractility ;
from ten hours to three days, if there be rigi-
dity of the joints, pitting of the soft parts,
the natural colour of the skin, loss of animal
heat, and no contraction under electric stimu-
lus; from three to eight days, if there be
flexibility (after rigidity) and no contractility ;
from five to twelve days, if the soft parts are
puffed, elastic, and shining. After the twelfth
day there is usually a separation of the epi-
dermis, as well as a green tint of the ab-
dominal integuments.+ But no certainty must
be attached to these statements; they are
merely approximative. The modifying in-
fluence of external media upon putrefaction is
all but unbounded. In summer as much
alteration may take place in five or six hours,
as in eight or even fifteen days of winter.

BIBLIOGRAPHY.— Hippocrates, Prenotionum Li-
ber, sect. i. Lord Bacon, Historia vite et mortis.
Lancisi, De subetaneis mortibus, 4to. Rom. 1707.
Winslow, Dissertatio an mortis incerta sint indicia.
4to. Paris, 1740. Bruhier, Dissertation sur l’incer-
titude des signes de la mort. 12mo. Paris, 1742.
Louis, Lettres sur la certitude des signes de la mort.
12mo. Paris, 1752. Sacht, Oratio qua senile fatum
inevitabile necessitate ex humani corp. mechanis-
mo scqui demonstratur. 4to. Ultraj. 1729. Van
Geuns, De morte corporea et causis moriendi. |
4to. Lugd. Batav. 1761. (Recus in Sandif. Thes.
vol. iii.) Lange, Facies Hippocratica levi penicillo
adumbrata. 8vo. Jen@, 1784. Ploucquet, Resp. F
Schmid. De unica vera causa mortis proxima.
4to. Tubing, 1786. C. Himly, Commentatio mor-
tis, historiam, causas, et signa sistens. 4to. Got-
ting. 1794. Awnschel, Thanatologia, sive in mortis
naturam, causas, genera ac species, et diagnosin
disq. 8vo. Gotting. 1795. Ontyd, De morte et
varia morendi ratione. 8vo. Lugd. Bat. 1797.
Bichat, R2cherches sur !a vie et la mort. 8vo. Paris,
an. viii. Ferriar, Medical histories and reflections.
Currie, on apparent death, 2d ed. 8vo. Lond. 1815.
Chaussier, Table des phénoménes cadavériques.
Adelon, Dict. de Méd. art. Mort. Beatty, Cyclo-
pedia of Pract. Med. art. Persons found dead.
Devergie, Dict. de Méd. et Chir. Prat. art. Mort.
R. B. Todd, Cyclop. of Pract. Med. art. Pseudo-
morbid appearances. W. Philip on the nature of
sleep and death. M. Julia de Fontenelle, Recher-
ches médico-légales sur l’incertitude des signes de
la mort, &c. 1834. The systematic works of —
Mahon, Foderé, Paris, Smith, Orfila, Devergie,
and Taylor, upon forensic medicine; and a chap-
ter on the causes of sudden death in Dr. Alison's —
Outlines of Physiology and Pathology. ‘a

(J. A. Symonds.) — j
: +e Ve

* Vol. xxxi. p. 248. See also an able article
upon Pseudo-morbid Appearances by Dr. R. B.Te

in the Cyclopedia of Practical Medicine.
/ + Op. cit.

ANALYTICAL INDEX

TO THE

FIRST VOLUME.

ABDOMEN (in anatomy generally) 1
Abdomen (human anatomy), 2

A

’

wails and regions of the, 2
structures composing the walls, 4
skin, 3* .
superficial fascia, $*
muscles and their aponeuroses, 4*
_ obliquus externus, 4*
obliquus internus, 6
cremaster, 6
transversalis abdominis, 7
rectus abdominis, 8
pyramidalis, 10
quadratus lumborum, 10
psoas magnus, 10
valk 11
iliacus internus, 11
- fascia transversalis, and
fascia iliaca, 11
sub-peritoneal cellular tissue, 13
fascia propria of the hernial sac, 13
septum crurale, 13
Peritoneum, 13
vessels and nerves of the abdominal walls, arteries, 14
veins, 15
lymphatics, 16
# r ; nerves, 16
a action of the abdominal parietes, 16
lominal cavity, 18 (see also Cavity)
,
escription of the absorbent system, 20 ‘
question of venous absorption considered, 24
mode in which the absorbents act, 28
cutaneous absorption, $1
specific uses of the different parts of the absorbent
system, and the relation which that system bears
to the other vital functions, 32
(class of invertebrate animals), 35
vision of the class, 36

respiration, 44

Acids,

animal, 47
Acrita (primary division of the animal kingdom), 47

Adhesion,

Adipocere, 55

Age, 64

pathological conditions of—inflammation, 61
hemorrhage, 62
excessive deposition, 62
extreme diminution, 62
adipose sarcoma, 63
steatoma, 63

lipoma, 63

melanosis, 64

growth, 65
maturity, 76
old age Tdecay )s 77

Albino, 83
Albumen, 88

VOL, I.

Amphibia (a class of vertebrate animals), 90

divisions, 91

osteology, 91

muscular beeen 95

organs of digestion, 95
lymphatic and lacteal system, 96
sanguiferous system, 96
respiration, 98

nervous system, 100

organ of vision, 101

organ of hearing, 101

organ of smell, 102

organ of taste, 102

dermal or tegumentary system, 102
transpiration and secretion, 104
restoration of lost parts, 104
reproduction, 105
metamorphosis, 106

Animal kingdom, 107

Divisions.— First sub- kingdom
1. Polygastrica, 108
2. Porifera, 108
3. Polypifera, 108
4. Acalephe, 108
5. Echinodermata, 109
Second sub-kingdom
6. Entozoa, 109
7. Rotifera, 109
8. Cirrhopoda, 110
g. Annelida, 110
10. Myriapoda, 110
11. Insecta, 110
12. Arachnida, 111
18. Crustacea, 111
Third sub- kingdom
14. Tunicata, 112
15. Conchifera, 112
16. Gasteropoda, 112
17. Pteropoda, 113
18. Cephalopoda, 114
19. Pisces, 114
20. Amphibia, 115
21. Reptilia, 115
22. Aves, 116
23. Mammalia, 117
summary, 117

Animal, 118

comparison of the organic and inorganic worlds, 118
physical qualities and elementary composition,
118

size, 118
chemical composition, 118
consistence, 119
elementary particles, 120
duration, 121
generation, 121 a3 :
actions of unorganized and of organized bodies, 121
origin, 122
preservation, 122
modifications (ages), 123
cessation of action (death), 193
comparison of vegetables and animals, 124 :
general physical qualities and material or chemi-
cal composition, 124
organic composition (textures), 125
vital manifestations or actions of vegetables and
animals (generally), 127
3G

810
Animal (continued.)

(particularly), origin, 129
nutrition, 190
digestion, 132
respiration, 132
circulation, 133
secretions, 135
heat, 136
light, 136
electricity, 137
motion and sensation, 137
comparison of animals with one another, 139
physical qualities and material constitution of
animals, 139
form, 139
structure, 140
actions of animals, 14!
absorption, 142
circulation, 143
assimilation, 144
sensibility, 144
locomotion, 145
reproduction, 145

Ankle, region of the, 147

skin, 147

subcutaneous cellular tissue, 148
fascia, 148

tendons, 149

muscles, 150

arteries, 150

veins, 151

lymphatics, 151

nerves, 151

Ankle, joint of the, 151

bones—tibia, 151
fibula, 151
astragalus, 152
ligaments, 152
synovial membrane, 153 at
mechanism and function of the ankle-joint, 153

Ankle-joint, abnormal condition of the, 154

accidents affecting the tendons, 154

ligaments, 154

bones, 155

luxation of the tibia inwards, 155_

complete luxation of the tibia inwards compli-
cated with a simple fracture of the fibula, 156

luxation of the tibia outwards, complicated with
simple fracture of one or both of the mal-
leoli, 158

luxation of the tibia and fibula forwards, and
also luxation of these bones backwards from
the articular pulley of the astragalus without
fracture, 159 7

complete luxation of the tibia forwards from the
articular part of the astragalus, complicated
with a simple fracture of the fibula, 159

partial luxation of the tibia forwards, with sim-
ple fracture of one or both of the malleoli, 160

partial luxation forwards of the tibia at the ex-
ternal ankle, with fracture of the fibula near
the malleolus, 161

luxation of the bones backwards at the ankle-joint,
162

morbid anatomy, 162
acute inflammation of the synovial membrane, 162
chronic disease, 163~

Annelida, (class of invertebrate animals), 164

divisions, 165

external conformation, 166
sensation, 167

nervous system, 168
organs of digestion, 168
circulation, 169
respiration, 170
generation, 171
reproduction, 172

Anus, 173

muscles and fasciz, 175
sphincter ani cutaneus, 176
sphincter ani internus, 176
ischio-rectal space, 177
obturator fascia, 177
transversi perinzi muscles, 177
levatores ani, 178
ischio-coccygei muscles, 179
rectum, 179 ,
abnormal condition of the anus and neighbouring
parts, 182
congenital malformations, 182
morbid conditions, 183
syphilis, 183
cancer, 184
excrescences, 184
rolapsus ani, 184
ssure, 185
contraction, 185
hemorrhoids, 185
fistula in ano, 186

Aorta, 187

arch of the, 188 gt
thoracic aorta, 189
abdominal aorta, 189

ANALYTICAL INDEX.

Aorta, (continued.) —
protien 190
anomalies, 190
diseased conditions, 191

branches of the aorta:—I. branches arising from the

arch, 192
He anterior or inferior coronary artery, 192
left superior or posterior coronary retry 192
II. branches of the thoracic aorta:—right
artery, 193
left bronchial artery, 193
cesophageal arteries, 193 __
posterior mediastinal arteries, 193
inferior or aortic intercostal arteries, 193
anastomoses, 194
III. branches of the abdominal aorta, 194
phrenic arteries, 194
-* “coeliac artery, 194
coronary artery of the stomach, 194
i tg artery, 194
splenic artery, 195
superior mesenteric artery, 195
arteries of the small intestines, 195
colic arteries, 195
a superior colic or colica media artery, 195
colica dextra or middle right colic artery, 196

ileo-colic, ccecal, or inferior right colic artery, 196

inferior mesenteric artery, 196
middle left colic artery, 196
inferior left colic, 196
superior hemorrhoidal artery, 196
lumbar arteries, 196
_ middle sacral artery, 197
Arachnida, (a class of invertebrate animals), 198
division of the class, 198
external covering or tegumentary system, 201
digestive system, 202
circulating system, 205
nervous system, 206
organs of secretion, 208

apparatus for secreting the irritating or poisonous

fluid, 208

apparatus for secreting the fluid that concretes in the

air, 209
generative system, 209
female generative system, 211

copulation, oviposition, and development of the
tuction of the

ova. Metamorphosis and rep
extremities, 211
exclusion or hatching of the spider, 214
4rm, (surgical anatomy of the,) 216
skin and subcutaneous tissue, 216
aponeurosis, 217
development, 217
Arm, (muscles of the,) 219
coraco-brachialis, 219
biceps flexor cubiti, 219
brachizus anticus, 219
triceps extensor cubiti, 219
Artery, (normal anatomy,) 220
anastomoses, 221
structure of arteries, 221
external tunic, 222
middle tunic, 222
internal tunic, 223 ‘
physical properties, 204
Artery, (pathological conditions of,) 226
wounds and injuries of arteries, 227
suppression of hemorrhage, 229
morbid state of arteries. Aneurism, 230
circumscribed false aneurism, 232
diffused aneurism, 237
traumatic aneurism, 237
secondary hemorrhage, 238
aneurismal varix, 241
varicose aneurism, 242
aneurism by anastomosis, 242
Articulata, (a division of the animal kingdom,) 244
(Subdivisions.)
Cirripeds, 245
Annelidans, 245
Insects, 246
Arachnidans, 246
Crustaceans, 246
Articulation, 246 +
(Structures entering into the composition of joints.)
bone, 247
cartilage, 247 :
(Various forms of articular cartilage,) 247
diarthrodial cartilage, 248
synarthrodial cartilage, 249
fibro-cartilage, 249
ligaments, 250°
capsular, 250
funicular, 251
elastic, 251
synovial membrane, 251
forms and classification of the articulations, 254
synarthrosis, 254
suture, 254
schindylesis, 255
gomphosis, 255
amphiarthrosis, 255

ronchial

ANALYTICAL INDEX. Bil

Articulation, (continued.)
dia is, 255
arthrodia, 256
enarthrosis, 256
inglymus, 256
iarthrosis rotatorius, 256

Aves, 265
divisions, 266
patie 270
table of the number of vertebra in birds, 272
table of the number of toe phalanges in birds, 259
fossil bones of birds, 289
myology, 290
pr n on land, 297
climbing, 297.
swimming, 297

297
diving, 297
flight, 297
nervous system, organ of vision, 303
lachrymal organs, 307
organ of hearing, 308
organ of taste, 311
organs of touch, 311
organs of digestion, 311
digestive glands, $25

absorben item, $27
orga Gicalation, vascular system, heart, 329

t sys

ns of

arteries, 332
respiratory organs, 341
araasporgens 3"

ans,

—, ee: 349
tegum 8 349

dewelupaicat of feathers, 351
organs of generation, male, 353
female organs of generation, 355

ay anatomy,) 358

Axilla, (;
A 2
mpypert Awl. 363

nches,

Back, region of the, surgical anatomy, 367
integu 367.
subcutaneous cellular tissue, 367
cttw 368
ymphatics, 368

» muscles of the, 368
rst layer, 369
second layer, 370
third layer, $71
fourth layer, 371
fifth layer, 372

Bile, 374
biliary calculi or gall-stones, 376
Bladder in anatomy, 376
Bladder of urine (normal anatomy), 376
urinary bladder in man, 377
shape, 377
organization of the bladder, 386
arteries, 386
veins, 386°
lymphatics, 387
nerves, $87 a
Bladder, abnormal anatomy of the urinary, 389
congenital conditions, 349
numerical changes, 389
absence, 389
plurality, 390
septa
extrophy or extroversion, 391
persistance of the urachus, 393
acquired changes, 393
sacculi or cysts, 393
changes of capacity, 394
decrease, 394
increase, 395
introversion, 395
hernia, 395
inflam mation, 396
idiopathic softening, 397
rupture, 398
fistulz, 398
hemorrhage from the bladder, 401
fungous tumours, 401
varices, 402
scirrhus and cancer, 402
paralysis, 402
' spasm, 403
Blood, 404
ee qualities, 404
globules, 404

table of the diameter of the globules of the blood, 407

chemical composition of the blood, 410
table of the solid and fluid parts of the blood, 412
in the human male, 412
female, 412
phenomena of coagulation, 413 :
analysis of the crassamentum (fibrine), 413
arterial blood, 414
venous blood, 414

Blood, morbid conditions of the, 415
excess in quantity, 416
deficiency, 416 ;
different relations of the solid and fluid parts to one
another, 416
specific Pravity, 416
table of specific gravities under several forms ©
disease, 417
poe gravity of the serum, 418
of the fibrine and red particles, 418 '
temperature, 418
alterations of the fibrine, 418
imperfect coagulation, 418
y coat, 419
polypi, 420
albumen, 422
hzmatosine, 422
oil, 422
saline constituents, 423
State of the, in inflammation, 423
in fever, 424
in scurvy, 425
in jaundice, 425
in disease of the kidney, 426
in diabetes, 427
in cholera, 497
in chlorosis, 428
in melanosis, 428
Bone, 430 :
physical properties and intimate structure of bone in
man, 430
shape, 430 ap ae f
periosteum and medulla and the organization 0
bone as part of the living system, 433
chemical composition, 437 ;
its peculiarities in other animals, 438
Fishes, 438
Amphibia, 438 a
Birds, 438
Mammalia, 438
Bone, pathological conditions of, 438
Class 1. Diseases of the osseous system, 439
rickets, 440
fragilitas, 441
mollities, 442
Class 2. Inflammation, 443
adhesion, 444
suppuration, 445
ulceration, 450
mortification, 453
necrosis, 453
scrofula, 454
syphilis, 454
Class 3. Structural diseases, 457
spina ventosa, 457
exostosis, 458
Ost€o-sarconia, 460
cancer, 463
fungus hematodes, 463
bloody cellulated tumour within bones, 464
Brachial or Humeral Artery, 465
relations, 465
branches, 465
superior profunda, 465
inferior profunda, 466
anastomotica magna, 466
anastomoses, 467
Brain, 467
Burse Mucose, 467
subcutaneous or superficial bursz, 467
deep burse, 467
deep vesicular burs, 467
deep vaginal burse, 468
structure, 469
contents, 469
function, 469
development, 469
pathological conditions of the bursz mucose, 469
Carnivora, skeleton, 47}
muscular system, 477
digestive organs, 477
chyliferous system, 479
organs of circulation, 479
organs of respiration, 480
nervous system, 480
organ of sight, 480
organ of hearing, 480
organ of smell, 481
organ of taste, 481
secretions. The urine, 481
generative system.
male organs, 482
female organs, 482
Carotid artery, 482
the primitive carotid, 483 aes = ;
relations of the trunk of the primitive carotid, 483
the external carotid, 484 .
branches of the external carotid, 485 - |
anterior branches of the external carotid, 435
posterior branches, 487
the internal carotid artery, 490
Cartilage, 495
temporary, 495

812

Cartilage, (continued.)
permanent, 495
organization, 496
accidental cartilage, 497
pathological conditions, 499
Sortie,
abdominal cavity, 500
cplgerizic region, 502
umbilical region, 504
hypogastric region, 505 f
abnormal conditions of the abdominal cavity, 507
congenital malformation of the abdominal pa-
rietes, 508
morbid conditions of the abdominal parietes, 509
congenital malformation of the abdominal cavity,

509
Cellular tisswe, 509
arrangement, 509
common cellular membrane, 510
special cellular membrane, 510
nerves of, 511
chemical composition, 511
properties, 511
morbid conditions of the cellular tissue, 513
inflammation, 518 ~
infiltration, 515
induration, 516
morbid growths, 516
foreign bodies, 516
Cephalopoda, (a class of invertebrate animals), 517
definition, 517
characters of the class, 517
division of the class into orders, 517
Order 1. Tetrabranchiata, 518”
Order II. Dibranchiata, 519
subdivision of the orders, 519
internal cartilaginous parts or endo-skeleton, 524
locomotive system, 525
digestive system, 531
organs of circulation, 538
respiratory organs, 542
nervous system, 547
organs of sense, 551
organ of sight, 551
organ of hearing, 554
‘ organ of smell, 554
organ of touch, 555
generative system, 555
Cerumen, 562
Cervical nerves, 562
Cetacea, (a class of the mammiferous vertebrate animals),
562
divisions, 563
organs of motion, 564
digestive organs, 571
organs of circulation, 576
organs of respiration, 579
urinary organs, 581
nervous system, 582
organ of sight, 584
organ of hearing, 586
organ of taste, 589
organ of touch, 589
organs of generation, 591
Cheiroptera, (a class of the mammiferous vertebrate ani-
mals), 594
osteology, 595
organs of the senses, 598
organ of vision, 598
organ of hearing, 598
organ of touch, 599
organ of smell, 599
digestive organs, 599
organs of generation, 600 ¢
Chyliferous system, (comparative anatomy), 600
Chyliferous system, (human anatomy,) See Lacteal, 602
Cicatrix, 602
Cilia, 606
in Infusoria, 606
in Polypi and Sponges, 609
ciliary motion of the ova of Polypi and Sponges, 613
in the Acalephe, 613
in the Actiniz, 614
in the Echinodermatata, 615
in the Annelida,
in the Mollusca, 619
of the ciliary motion of the embryo of the Mollusca,
626
phenomena of the ciliary motion in the Vertebrata,
628
Reptiles, 628
Birds, 631
Mammalia, 631
summary of the animals in which the ciliary motion
has been discovered, 632
organs or parts of the body in which the ciliary motion
has been ascertained to exist, 632
of the ciliary motion in the embryo, 633
figure, structure, and arrangement of the cilia in
general, 633
of the appearance of the cilia in motion, 634
duration of the ciliary motion after death and in
separated parts, 634

ANALYTICAL INDEX.

~~ effects of external agttits 68 ON <a et 634
effects of inflammation, 635 ee hye ;

of the power by which the cilia are moved, 635 —

of the motion caused in fluids by the cilia, 636

course of the blood in Man, 638

proofs of the circulation, 640

ete Shad.

course of the blood in the foetus, 640 <P

course of the blood in various animals, 641
in warm-blooded animals, 642 at eeitow tet
in cold-blooded vertebrated animals, 642 —
Reptiles, 643 *
portal circulation in Reptiles, 646
in Fishes, 646
rtal circulation in Fishes, 647
course of the blood in invertebrate animals, 648
Mollusca, 648
Articulata, 650
Annelida, 650
Insects, 651
Crustacea, 652
Arachnida, 652
Zoophytes, 653
Entozoa, 654
Acalephe, 654 -
- Infusoria, 654
Polypi, 654 F
phenomena of the circulation and powers moving the
blood, 655 ,
flow of the blood through the heart, 655
phenomena of the arterial circulation, 658
velocity of the blood in different arteries, 659
force of the blood in the arteries and force
of the heart, 661
arterial pulse, 663 ‘
vital properties of the arteries, 664 :
influence of the vital powers of the arteries
on the circulation, 667
phenomena of capillary circulation, 669
structure and distribution of the capillary vessels,
669 ir
properties of the capillary vessels, and their in-
fluence on the circulation, 671
phenomena of the venous circulation, 674
relation of the circulation to other functions,
1, to respiration, 675 t
2. circulation within the cranium, 678
3. influence of varieties in the distribution of
arteries and veins upon the circulation, 678
4. influence of the nervous system upon the circu-
lation, 679 :
Cirrhopoda, a class of invertebrate animals, 683
division, 684
external coverings and organs of support, 684
locomotion, 687
motility and sensation, 688
circulation, 689
respiration, 689
secretion, 690
reproduction, 690
development of the egg and young, 692
Cirronosis, 694
Colloid, see Scirrhus. "
Conchifera, (a class of invertebrate animals), 694
division, 695
organs of digestion, 695
organs of circulation, 698
organs of respiration, 699
organs of generation, 700
organs of motion, 700
nervous system, 704°
skin and its appendages, 705
siphons, 707
shell, 707
general structure, 707
hinge, 707
ligament, 708
cardinal edge, 708
surfaces of the valves, 710
classification of the conchifera, 714
Contractility, 716
I. irritability, 717 pte a
II. vital Fs eabed or-property of irritability, 719
i

1II. conditions necessary to the contractile powers,
721
1V. laws regulating the vital powers of contractile

parts, 723
Cranium, (comparative anatomy,) 724
human anatomy, 725
bones of the cranium, 726
sphenoid bone, 726
frontal bone, 728
Cranium, ethmoid bone, 730
occipital bone, 731
temporal bone, 733
parietal bone, 735 3
articulations of the cranial bones, (sutures,) 736
surfaces of the cranium (external surface), 737
internal surface, 738

-

correspondence of the external and internal sur-_

faces, 739 Hi
measurements of the cranium, 739
analogy between the cranium and a vertebra, 740

i> | eA ag

ANALYTICAL INDEX.

Cranium, (continued.)
and several vertebre, 740
development of the cranial bones, 741
mechanical adaptation of the cranium, 742
abnormal conditions of the cranium, 744
acephalia, 744
encephalocele, 744
insu t evolution, 744
thinness of the parietes (hydrocephalus,) 744
ossa Wormiana, 744
persistence of certain sutures, 744
want of symmetry, 744
obliteration of the sutures, 745
changes from age, 745
extraordinary thickening, 745
exostosis, 745
thinness, 745

extraordi
effects of inflammation, 745

sarcoma, 746
Cranium (regions and muscles of the), division into re-

.,, gions, 746

occipito-frontal region, 747
ntegument, 747
subcutaneous tissue, 747
muscles, 747

occipita-frontalis, 747
corrugator supercilii, 748

nerves, 748
arteries, 748
veins, 748
lymphatics, 749

t ietal region, 74

emporo-pari region, 749
temporal fascia, 749
muscles, 749
nerves, 749
arteries, 749
veins, 749
lymphatics, 749
pericranium, 749

50
table of the arrangement of the class, 751
$1. skin or tegumentary skeleton, and organs of loco-
motion, 752
moult or 1 ame of renovation of the tegumen-
tary skeleton, 759 |
reproduction of extremities, 760
§ 2. apparatus of sensation, A. nervous system, 762
B. organs of the senses,
767
touch, 767
taste, 768
smell, 768
hearing, 768
sight, 769

¢

813

Crustacea, (continued.)
$3. apparatus of nutrition, 771

A. apparatus of Caen 3 mouth,
_ and its appendages, 771
intestinal canal, 773
mouth, esophagus, stomach, 773
Pulaiy system, 775

B. blood and circulation, 775

; heart and arteries, 776
venous sinuses, 777

branchio-cardiac (efferent) vessel, 777
entrance of the blood into the heart, 777
respiration, 777
generation, 782
ovum, 785
incubation and development, 7385
Cyst, 787
first class of cysts, 788
second class, 789
Death, 791
molecular death, 791
destruction of the tissues, 791
arrest of the fluid of nutrition, 792
retention of fluid in the tissues, 792
depravation of the fluid of nutrition, 792
extinction of irritability, 793
systemic death, 794 |
syncope by asphyxia, 794
by nervous lesion, 794
by injuries of the heart itself, 795
of other organs, 795
by mental emotion, 796
by hemorrhage, 796
by poisons, 797
by cold and lightning, 797
by inanition, 797
by disease, 797
by old age, 798
signs of approaching death, 798
delirium, 799
death-struggle or agony, 800
relaxation of the muscles, 800
weakness of voice, 800
decline of the circulation, 801
state of the respiration, 801
loss of heat, 801
state of the secretion, 801
facies Hippocratica, &c. 802
signs of actual death, 803
of extinction of the vital functions, 803
changes in the tissues, 804
changes in the external appearance of the body,

807

END OF VOL. I.

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