€oQese ot ^tpsftcianä anb ^urgeonä
Ititirarp

MANUAL

OF

COMPARATIVE ANATOMY.

,1 . VX/L^ >

MANUAL

OF

COMPARATIVE ANATOMY,

r

i

TRANSLATED FROM THE GERMAN

y OF

/
/

J. R BLUMENBACH,

WITH ADDITIONAL NOTES,

By WILLIAM LAWRENCE, Esq. F.R.S.

SURGEON TO ST. BARTHOLOMEW'S HOSPITAL, TO BRIDEWELL,
AND BETHLEM HOSPITALS,

&C. &C. x'

n

SECOND EDITION, REVISED AND AUGMENTED,

By WILLIAM COULSON,

DEMONSTRATOR OF ANATOMY AT THE MEDICAL SCHOOL, ALDERSGATE STREET,
AND MEMBER OF THE ZOOLOGICAL SOCIETY.

LONDON:

PRINTED FOR W. SIMPKIN AND R. MARSHALL,

STATIONERS'-HALL COURT, LUDGATE STREET.

1827.

}

J. M'Creery, Tooks Court,
Chancery*lane, London»

'^m /^/y

/FX^

ADVERTISEMENT.

In submitting this work to the public, the Editor
deems it right to state briefly in what respects the
present edition of Mr. Lawrence's translation of
Blumenbach differs from the original edition of
1807. The difference consists partly in the addition
of new matter, and partly in a new, and, he trusts,
improved arrangement both of the text of the author,
and of the additional notes of the Translator.

With respect to the new disposition of the matter,
the notes of Blumenbach have been incorporated,
whereverithasbeenpracticabletoeffect such an union,
with the text ; an arrangement which is sanctioned, in
many instances, by the authority of the author him-
self in the later editions of his work; and which will
be found, it is hoped, to contribute not less to the pro-
fit, than to the convenience of the student. Frequent
annotations necessarily divert the attention of the rea-
der from the chain of reasoning, or the detail of facts
which the text may present to him ; and there is the
less reason for isolating the information contained in
the notes of Blumenbach, as it is for the most part

b

11 ADVERTISEMENT.

strictly relevant to the subject matter of the text.
The additional notes of Mr. Lawrence, which, in
the edition of 1807, were annexed en masse to the
end of each chapter, have, in this edition, been
printed in a distinct type at the end of each para-
graph of the text which they are designed to illus-
trate.

Of the new matter, part has been introduced by
the author in editions of this Manual, subsequent to
that translated in 1807, and part has been annexed
to, or incorporated with the notes of Mr. Lawrence
by the present editor.

The works of the more recent physiologists and
comparative anatomists, especially those of Cuvier,
Blainville, Rudolphi, Carus, Meckel, Tiede-
mann, and the Lectures of Sir E. Home, have been
diligently examined, with a view of supplying such in-
formation as the lapse of twenty years had rendered
necessary, in order to complete the plan of illustra-
tion adopted by the Translator. Many scarce and
valuable monographs have also been consulted for
that purpose. The information derived from these
sources is in some instances sufficiently distinguish-
ed, by the dates of the works cited, from former addi-
tions to this Manual, and, where there is no such dis-
tinction apparent on the face of the additional matter,
the Editor has not thought it necessary to point out
what has been added to the commentaries of Mr.

ADVERTISEMENT. 11!

Lawrence, preferring rather to place his own hum-
ble endeavours to increase the utility of the work
under the shelter afforded to them by the name of
the distinguished Translator.

To that eminent individual the Editor has now to
make his public acknowledgments for the mark of
friendship and confidence with which he has been
honoured, in being intrusted with the superintend-
ence of this publication. For the sake of the sci-
ence, indeed, he regrets that the numerous profes-
sional avocations of Mr. Lawrence have prevented
him from presenting the public with an improved
edition of this, one of his earliest literary produc-
tions; but he trusts, that as far as diligence and zeal
can supply the want of the Translator's superintend-
ing care, the confidence which has been reposed in
him has not been entirely misplaced. Mr. Law-
rence's translation of this work was produced at
the outset of his professional life, at a time when a
knowledge of the German language might be consi-
dered a rare acquisition in this country; and his il-
lustrations of the text, even at this early period of
his career, aflforded an earnest of that reputation
which he has since acquired by the splendour of
his physiological researches. Blumen bach has him-
self borne ample testimony to the merits of his com-
mentator ; indeed it is as gratifying to remark the spi-
rit of candour and cordial approbation with which

b 2

IV ADVERTISEMENT.

the labours of our distinguished countryman are
uniformly noticed by the continental writers, as it is
humiliating to reflect on the spirit of envy and ma-
lignity by which they have been assailed at home.
Envy and malignity, however, have done their
w^orst ; it may be said rather that they have had the
eifect of establishing the fame of Mr. Lawrence,
and of placing, beyond all competition, his claims
to the highest rank in his profession.

The Editor cannot conclude these observations
without expressing his acknowledgments to Mr.
Clift, the conservator of the Hunterian Museum, for
the great facilities he has afforded him in the prose-
cution of inquiries connected with this publication.
The value of the Hunterian Museum, with a view
to any practical advantage that can be derived from
it in physiological or pathological investigations, is
indeed greatly diminished by the want of a digested
catalogue of its contents. This want will, it is to
be hoped, be speedily supplied ; in the mean time
nothing is better calculated to diminish the incon-
veniences resulting from it, than the urbanity, and
the readiness to afford information, which are dis-
played on all occasions by the present conservator.

William Goulson.

59, Aldersgate Street,
Oct. 1, 1827.

THE AUTHOR'S PREFACE

TO

THE FOURTH EDITION.

I WAS first led, both by inclination and by the nature
of my professional pursuits, to devote the greater
portion of my time to the study of physiology, or the
foundation of medical science, as it has been termed
by Zimmermann, and to natural history, or the ma-
teria prima philosophice, as it has been called by Ba-
con. I soon became convinced, and experience has
confirmed my conviction, that Haller was right
when he said of comparative anatomy, that it had
thrown more light upon physiology than even the
dissection of the human subject; an opinion which
has been further sanctioned by the authority of Leib-
NiTz, who has declared comparative anatomy to be
the soul of that branch of knowledge which is de-
dicated to the history of the animal kingdom. If I

VI AUTHOR S PREFACE.

may venture to believe that I have not laboured in
vain in these two departments of science, the suc-
cess of my efforts is to be attributed to the collateral
assistance which 1 have derived from comparative
anatomy. As I may at least claim the merit of
having been the first to deliver lectures annually on
this subject, in Germany, and of having by these
means excited a taste for the science, and a zeal to
contribute to its advancement ; so I trust that this
edition of my Manual, the first work of the kind
which has ever appeared on comparative anatomy,
as applied to the whole animal kingdom, will fur-
ther facilitate the study, and render it more univer-
sally useful. I have the more reason to think that
my readers will approve the plan of this work, as it
is, in fact, the same vv^hich 1 have pursued in my
elementary treatises on physiology and natural his-
tory ; and which, from the various advantages it com-
bines, has been found best calculated to afford faci-
lities to students.

To give effect to such a plan it was necessary to
make a judicious selection from the vast mass of
materials which have been accumulated by the la-
bours of comparative anatomists. This I have en-
deavoured to accomplish, while at the same time I
have kept in view the application of the science to
physiology and natural history, and have occasion-
ally interspersed a few remarks illustrative of these

AUTHOR S PREFACE. Vll

branches of knowledge. It is evident that a minute
description of the muscles, vessels, nerves, &c.,
of the various classes of animals, could not be
comprised within the limits which I have prescribed
to myself. Comparative Osteology, however, de-
serves a more detailed examination, for the skele-
tons of red-blooded animals are not only intimately
connected with the rest of their anatomical struc-
ture, but also with their form, economy, and peculiar
habits.

To domestic animals, and to such as the sports of
the field bring most frequently under our notice, I
have paid particular attention ; partly, because such
animals are most easily procured for dissection, and
partly on account of the great interest which is
likely to be taken in a correct knowledge of their
structure. With regard to foreign animals, I have
uniformly adverted to their most striking peculiari-
ties.

I have carefully cited my authorities for such
facts as I have not myself had an opportunity of
verifying; availing myself, in such cases, partly of
the best engravings which have been published, and
partly of the best monographs, and papers which
have appeared on the subject of comparative anato-
my in periodical collections ; so that I have scarce-
ly omitted to notice a single author who has contri-
buted any thing of importance, and the notes to this

vm AUTHOR S PREFACE.

Manual furnish a complete synopsis of the literature
of the science.

I have devoted a large portion of the work to the
classes of vt^arm-blooded animals, as those in which
readers, whose time will not admit of extended in-
vestigation, will take the greatest interest. I have
not, however, neglected the classes of cold-blooded
animals, and the two last classes of the Linusean
system, having generally explained the comparative
anatomy of the invertebrated animals, by an exam-
ple or two taken from each class.

To such authorities as the large systematic works
of Blainville, Carus, Cuvier, Geoffroy, Meck-
el, RuDOLPHi, TiEDEMANN, and Treviranus, I
now, to avoid frequent repetition, refer once for all.
The same observation applies to the engravings
given by some of these writers, and especially by
CuviER and Carus, as well as to the masterly mo-
nographs of BOJANUS, CUVIER, HoME, SPIX,

TiEDEMANN, &c., and to the copious additional
notes with which the celebrated Lawrence has
enriched his translation of this Manual.*

I shall scarcely be expected to offer any apology

* Notwithstanding this observation, the author has very fre-
quently quoted Mr. Lawrence's notes ; but in this edition, where
the notes so cited immediately follow the text, references of this
kind are of course omitted. — Ed.

AUTHOR S PREFACE. IX

for not having translated many well known technical
Latin terms, the translation of which would, in fact,
have rendered the things signified less intelligible;
nor is it, I trust, necessary for me to enlarge on the
numerous additions and improvements by which
the utility of the work has been increased in this
edition.

J. F. Blumenbach.

Gottingen,
March 31, 1824.

INTRODUCTION.*

Anatomical structure is the natural foundation
on which a systematic arrangement of the different
classes and species which compose the animal king-
dom may be established. Aristotle has adopted
to a certain extent this basis of classification ; but it
is evident that no great advances could be made by
the ancients in a branch of knowledge, which pre-
supposes an intimate acquaintance with the struc-
ture and organization of animals. No attempt at
classification before the time of Linnaeus has any
pretensions to the name of a system affording accu-
rate criteria for distinguishing the different classes
of animals. The classification of Linnaeus, which
is adopted with some modifications by Blumenbach
in the following work, is founded on the observation

* This introduction is substantially the same as that given by
Mr. Lawrence in the original editio« of this work.

XU INTRODUCTION.

of differences of structure in the organs of circula-
tion in such animals as possess a cardiac system.

Mammalia, viviparous . ^Heart furnished with two

J ventricles, two auricles;
Birds, oviparous • • • ( blood warm and red.
Amphibia, respiring by y^ Heart furnished with one

lungs 1 ventricle and one au-

Fishes, breathing by j ricle; blood cold and

gills ...... v red.

Insects, furnished with "x

antennae .... f Sanies cold and colour-
Vermes, furnished with C less,
tentacula .... J

Animals may be divided into two great families;
the first family possessing vertebrae and red blood ;
the second without vertebrae, and most of them with
white blood. The former have always an internal
articulated skeleton, of which the chief connecting
part is the vertebral column. The anterior part of
this column supports the head ; the canal which
passes from one end of it to the other incloses the
common fasciculus of the nerves ; its posterior extre-
mity is most frequently prolonged, in order to form
the tail, and its sides are articulated with the ribs,
which are seldom wanting. None of this family of
animals has more than four limbs, some of them
have two only, and others have none.

INTRODUCTION. Xlll

The brain is inclosed in a particular osseous ca-
vity of the head, called the cranium. All the nerves
of the spine contribute filaments to form a nervous
cord, which has its origin in the nerves of the cra-
nium, and is distributed to the greater part of the
viscera.

The senses are always five in number. There are
always two ej^es, moveable at pleasure. The ear
has always at least three semicircular canals. The
sense of smell is always confined to particular cavi-
ties in the fore part of the head.

The circulation is always performed by one fleshy
ventricle at least; and where the ventricles are two
in number, they are always close together, forming a
single mass. The absorbent vessels are distinct from
the sanguiferous veins.

The two jaws are always placed horizontally, and
open from above downwards. The intestinal canal
is continued without interruption from the mouth to
the anus, which is always placed behind the pelvis,
that is, behind the circle of bones which affords a
fixed point for the posterior extremities. The in-
testines are enveloped within a membranous sac,
termed peritoneeum. There is always a liver and a
pancreas, which pour their secretions into the cavity
of the intestines; and there is always a spleen,
within which part of the blood undergoes some pre-
paratory change before it is sent to the liver.

XIV INTRODUCTION.

There are always two kidneys for the secretion of
urine, placed on the two sides of the spine, and
without the peritonaeum. The testicles also are
always two in number. There are always two bo-
dies called atrabiliary capsules, placed over the kid-
neys ; the use of them is unknown.

Animals with vertebrae are subdivided into two
classes, one of which is warm-blooded, and the
other cold-blooded.

Warm-blooded vertebrated animals have always
two ventricles and a double circulation. They re-^
spire by means of lungs, and cannot exist without
respiration. The brain almost always fills the cavity
of the cranium. The eyes are covered with eye-
lids. The tympanum of the ear is sunk within the
cranium; the different parts of the labyrinth are
completely inclosed within bone; and besides the
semicircular canals, the labyrinth contains the coch-
lea, with two scalie^ resembling the shell of the snail.
The nostrils always communicate with the throat,
and afford a passage for the air in respiration. The
trunk is furnished with ribs, and aUnost all the
species of this branch of animals have four limbs.

Cold-blooded vertebrated animals resemble one
another more by their negative than their positive
characters. Many of them are destitute of ribs;
some of them are totally destitute of limbs. The
brain never fills the whole cavity of the cranium.

INTRODUCTION. XV

The eyes seldom have moveable eyelids. The tym-
panum of the ear, when present, is always close to
the surface of the head ; it is often absent, as are
likewise the ossiculaauditus; the cochlea is always
wanting. The different parts of the ear are not
firmly attached to the cranium; they are often
loosely connected to it in the same cavity as the
brain.

Each of these two branches is subdivided into
two classes.

The two classes of warm-blooded animals are the
Mammalia and Birds.

The Mammalia are viviparous, and suckle their
young with milk secreted by the mammae. The fe-
males have consequently always the cavity termed
uterus with two cornua, and the males have always
a penis.

The head is supported on the first vertebra by
two eminences. The vertebrae of the neck are ne-
ver less than six, nor more than nine. The brain
has a more complicated structure than in other
animals, and contains many parts which are not to
be found in the other classes, such as the corpus
callosum, fornix, pons, &c.

The eyes have two eyelids only. The ear con-
tains four small bones, articulated together, and has
a spiral cochlea. The tongue is quite soft and
fleshy. The skin is covered entirely with hairs, iu

XVI INTRODUCTION.

the greatest number, and in all it is covered par-
tially.

The lungs fill the cavity of the chest, which is
separated from the abdomen by a fleshy diaphragm.

There is one larynx only, situated at the basis of
the tongue, and completely covered by the epiglottis,
when the animal swallows.

The lower jaw only is moveable; both jaws are
covered with lips.

The biliary and pancreatic ducts are inserted
into the intestinal canal at the same place. The
lacteal vessels convey a white milky chyle, and pass
through a number of conglobate glands, situated at
the mesentery. A membrane, called omentum, sus-
pended from the stomach and adjacent viscera, co-
vers the fore part of the intestines. The spleen is
always upon the left side, between the stomach,
ribs, and diaphragm.

Blumenbach establishes the following orders in
this class :*

Ordo I. BiMANUs. Two handed.
Genus. Homo.

JI. QuADRUMANA, four-haudcd animals : having a
separate thumb capable of being opposed to

* Vid. Gore's translation of Blumenbach's Natural History^
p. 32.

INTRODUCTION. XVll

the other fingers, both in their upper and lower
extremities, teeth like those of man, except that
the ciispidali are generally longer.

1. Simice, apes, monkeys, baboons.

2. Lemur, macauco.

III. Chiroptera.

The fingers of the fore ieei, the thumb excepted,
are, in these animals, longer than the whole body ;
and between them is stretched a thin membrane for
flying. Hence they are as little capable of walking
on the ground as apes, with their hands, or sloths,
with their hooked claws, which are calculated for
climbing.

1. Vespertilio, bat, calugo, &c.

IV. DiGITATA.

Mammifera, with separate toes on all four feet.
This order contains the greatest number of genera
and species, and is therefore conveniently divided,
according to the diflferences of the teeth, into three
families, glires,fera, and hruta.

(A) Glires.

With two chisel-shaped incisor teeth in each jaw,
for the purpose of gnawing without canine teeth.

1. Sciurus, squirrel,
c

XVlll INTRODUCTION.

2. Glis, dormouse [Myoxus, Lirm.)

3. Mus, mouse and rat.

4. Mat^mota, marmot.

5. Savia, guinea-pig.

6. Lepus, hare and rabbit.

7. Jaculus, jerboa.

8. Hystrix, porcupine.

(B) Fer^.

With pointed or angular front teeth, and mostly
with only a single canine tooth on each side, which
is generally, however, of remarkable size and
strength. The carnivorous animals, properly so
called, and some other genera with teeth of the
same kind, compose this family.

1. Erinaceus, hedgehog.

2. Sorex, shrew.

3. Talpa^ mole.

4. Didelphis marsupialis, opossum.

5. Viverrce, weasels, ferret, polecat, civet.

6. Mustela, stunk, stoat, &c.

7. Ursus, bear.

8. Canis, dog, wolf, jackall, fox, hyaena.

9. Felis, cat, lion, tiger, leopard, lynx, panther,

&c.

The three first genera belong to the insectivora of
CuviER ; their feet are short, and their power of mo-

INTRODUCTION. XIX

tion weak. They have no coecum, and walking they
rest the whole of the foot on the ground. They live
principally on insects, whence their name is derived.
The fourth genus belongs to the marsupialia of Cu-
viER ; the animals of this class have a pouch in the
abdomen which contains the mamm^, as well as
the young in their early state. The remaining ge-
nera, with the exception of the bear, belong to the
digitigrada of Cuvier.

(C) Bruta.

Without teeth, or at least without front teeth.

1. Sradypus, sloth.

2. Myrmecophaga, ant-eater.

3. Manis, scaly ant-eater.

4. Dasypus or Tatu, armadillo.

This order forms the edentata of Cuvier, the
tongue is long, slender, and projectile, for seizing
the insects on which the animals live. The armadillo,
manis, ant-eater, and ornithorhynchus, or duck-billed
animal, belong to this order.

V. SoLiDUNGULA (Solipeda, Cuv.).

A single toe on each foot, with an undivided
hoof. Large intestines, and particularly an enor-
mous coecum. Incisors in both jaws.
1. Equus, horse or ass.
c 2

XX INTRODUCTION.

VI. BisuLCA (Pecora).

These are the ruminantia ofCuviER, their hoof is
divided. INo incisors in the upper jaw. Stomach
consisting of four cavities. Rumination of the food.
Long intestines.

1. CameZw^, camel, dromedary, lama.

2. Capra, sheep, goat.

3. Antilope, antelope, chamois.

4. Bos, ox, buffalo.

5. Girqffci, giraffe, or camelopard.

6. Cervus, elk, deer kind.

7. Moschus, musk.

Vir. MuLTUNGULA (Belluae).

Animals of an unshapely form, and a tough and
thick hide ; whence they have been called by Cu-
viER pac/ii/dermata [from Trax^e thick, and ^tpjua skin).
They have more than two toes; incisors in both
jaws, and in some cases enormous tusks.

1. Sus, pig kind, pecari, babiroussa.

2. Tapir.
S. Elephas.

4. Rhinoceros.

5. Hippopotamus.

VIII. Palm ATA.
Mammifera with webbed feet, the genera being

INTRODUCTION. XXI

divided (as in the order Digitata) according to the
forms of the teeth into three families:

(A) Glires. (B) FercB. (C) Bruta.

(A) Glires.

With chisel-shaped gnawing teeth.
Castor, beaver.

(B) Fer^.

With the teeth of carnivorous animals.
Phoca, seal.

(C) Bruta.

Without teeth, or at least without front teeth.

Ornitiiorhynchus, duck-billed animal.
Trichechus, walrus.

The last genus of the order, together with the
])hoca, (seal) constitutes the amphibia of Cuvier.
These animals have short members adapted for
swimming.

IX. Cetacea.

' Whales living entirely in the sea, and formed like
fishes ; breathe by an opening at the top of the head,
called the hlowing-hole, through which they throw
out the water, which enters tlieir mouth with the food.

XXll INTRODUCTION.

Smooth skin covering a thick layer of oily fat. No
external ear. A complicated stomach. Multilobu-
lar kidneys; larynx of a pyramidal shape, opening
towards the blowing hole. Testes within the abdo-
men. Mammae at the sides of the vulva. Bones of
the anterior extremity concealed and united by the
skin, so as to form a kind of fin.

1. Monodon, narwhale, sea-unicorn.

2. Balana, proper whales.

3. Physeter, macrocephalus, white whale.

4. Delphinus, dolphin, porpoise.

Cuvier distributes the class mammalia into three
grand divisions :

1. Those which have claws or nails, (inammiftres ä
ongles) including the following orders : bimana,
quadrumana, chiroptera, plantigrada, Carnivora, pe-
dimana, rodentia, edentata, tardigrada.

2. Those which have hoofs {mammif. ä ongles) in-
cluding the pachydermata, ruminantia, and soli-
peda.

3. Those which have extremities adapted for
swimming {mammif. ä pieds en nageoire). Amphibia
and cetacea.

BIRDS.

Birds are oviparous. They have only one ova-
rium and one oviduct, in which they differ from other

INTRODUCTION. XXIU

oviparous animals. The head is supported on the
first vertebrae of the neck by a single eminence. The
vertebrae of the neck are very numerous^ and the
sternum very large. The anterior extremities are
used for flying, and the posterior for walking.

The eyes have three eyelids. There is no exter-
nal ear ; the tympanum contains only one bone, and
the cochlea is a cone slightly curved. The tongue
has a bone internally. The body is covered with
feathers. The lungs are attached to the ribs. The
air passes through the lungs in its way to the air-
bags, which are dispersed throughout the body.
There is no diaphragm. The trachea has a larynx
at each end, and the upper one has no epiglottis.
The upper mouth consists of a horny bill without
lips, teeth, or gums, and both mandibles are move-
able.

The pancreas and liver send out several excretory
ducts, which enter the intestines at different places.
The chyle is transparent, and there are no mesenteric
glands nor omentum. The spleen is in the centre
of the mesentery. The ureters terminate in a cavity
called the cloaca, which also affords an exit to the
solid excrement and to the eggs. There is no uri-
nary bladder.

This class cannot be distributed into orders so
clearly distinguished by anatomical characters as
the preceding one. Blumenbach divides them into
two leading divisions.

XXIV INTRODUCTION.

(A) Land Birds.

Order I. Accipitres. Birds of prey, almost all with
short strong feet, large sharp claws, and a strong
hooked beak, which for the most part termi-
nates above in two short cutting points, and is
commonly covered at the root with a fleshy
membrane. A membranous stomach, and short
coeca.

1. Vultw\ vultures.

2. Falco, falcon, eagle, hawk, kite.

3. StriXi owl.

4. JLanins^ shrike or butcher-bird.

II. Levirostres. Light-billed birds, having a large
hollow bill.

1. Psittacus, parrot kind.

2. Hamphastos, toucan.

3. JBuceroSy rhinoceros bird.

Iir. Fici. The birds of this order have short feet,
and commonly a straight bill.

1. Picus, woodpecker.

2. Jynx, wryneck.

3. Sitta^ nuthatch.

4. Alcedo, kingsfisher.

5. Merops, bee-eater.

6. Upupttj hoopoe.

INTRODUCTION. XXV

7. Certhio, creeper.

8. Trochilus, himiming birds, &c. &c.

IV. CoRACES. The birds of this order have short
feet with a strong bill, convex on the upper part,
and of moderate size.

1. JBuphagar, ox-pecker.

2. Crotophaga, razor-billed blackbird.

3. Corvus, crow, raven, jackdaw, magpie,

jay, &c.

4. Coracias, roller.

5. Gracula, minor grakle.

6. Pai^adisea, birds of paradise.

7. Cuculus, cuckoo.

8. Oriolus, oriole.

V. Passeres. Small singing birds, with short and

slender feet, and conical sharp-pointed bills of
various size and form.

1. Alauda, lark.

2. Sturnus, starling.

3. Turdus, thrush, blackbird.

4. Ampelis, chatterer.

5. Loxia, cross-billed tribe.

6. Emherizo, bunting.

7. Fringilla, finches, canary-bird, linnet,

sparrow.

8. Musicapa, fly-catcher.

XXVI INTRODUCTION.

9. Motacilla, nightingale, redbreast, wren.

10. Pipra, man akin.

11. Parus, titmouse.

12. Hirundo, swallow, martins, &c.

13. Caprimulgiis, goatsucker, &c.

VI. GallinjE. Gallinaceous birds, mostly domesti-
cated, have short legs with a convex bill, which
is covered with a fleshy membrane at its base,
and of which the upper half overlaps the lower
on each side. They possess a large crop.

1. Colmnha, pigeons.

2. Tetrao, grouse, quail, partridge.

3. Numida, guinea-fowl.

4. Phasianus, cock pheasant.

5. Crax, curesso.

6. Meleagris, turkey.

7. Pavo, peacock.

8. Otis, bustard.

VII. Struthiones. Struthious birds. The largest
of the class ; possess extremely small wings,
and are therefore incapable of flight ; but run
very swiftly.

1. Strut/no, ostrich, cassowary.

2. Didus, dodo.

INTRODUCTION. XXVÜ

(B) Aquatic Birds.

Order I. Grall^e. These birds have cylindrical
bills of various lengths ; long stilt-like legs ;
long neck, and short tail. They mostly live in
marshes, and feed on amphibia.

1. Phcenicopterus, flamingo.

2. Platalcea, spoonbill,

3. Palamedea, horned screamer.

4. Ardea, crane, stork, heron, bittern.

5. Tantalus, ibis, &c.

6. Scolopax, woodcock, snipe, curlew.

7. Tringa, lapwing, ruffs and reeves.

8. Charadrius, plover.

9. Hamatopus, sea-pie.

10 Fulica, water-hen, coot.

11. Parva, spur-winged water-hen.

12. Rallus, rail.

13. Psophia, trumpeter.

II. Anseres. Swimming birds; web-footed; the
upper mandible mostly ends in a little hook,
and, together with the lower, is in most instances
plentifully supplied with nerves.

1. Rhmcops, sea-crow.

2. Sterna, noddy, silver bird.

3. Colymbus, diver.

XXVIU INTRODUCTION.

4. Larus, gull.

. 5. Plolus, darter.

6. Phceton, tropic bird.

7. Procellaria, petrel.

8. Diomedea, albatross.

9. Pelecanus, pelican, cormorant.

10. Anas, swan, duck, goose.

11. Mergus, goosander.

12. Alca, auk, puffin.

13. Aptenodytes, penguin.

The two classes of cold-blooded vertebral animals
are the

AMPHIBIA AND FISHES.

The animals of the former class differ from one
another in many very essential particulars, and have
not so many characters in common as the other
classes. Some of the reptiles walk, some fly, some
swim, many can only creep. The organs of the
senses, and particularly the ear, differ almost as
much as the organs of motion ; none of the reptiles,
however, have a cochlea. The skin is either naked
or covered with scales. The brain is always very
small. The lungs are in the same cavity with the
other viscera; there are no air-bags beyond the
lungs, but the cells of these organs are very large.
There is but one larynx, and no epiglottis. Both
the jaws are moveable. There are neither mesente-

INTRODUCTION. XXIX

ric glands, nor omentum. The spleen is in the centre
of the mesentery. The female has always two Ova-
ria and two oviducts. There is a bladder.

The class of reptiles, in the arrangement of Cuvier,
corresponds to the orders of reptiles pedati, and ser-
pen tes apodes, belonging to the class of amphibia
in the Sy sterna Natur ce of Linnaeus.

Order I. Reptilia, having four feet, {quadrupeda
ovipard) the toes of which are, according to
their mode of life, either separate, (pedes digita-
ti) connected by membranes, [palmati] or con-
founded with one another in the form of a fin
(jpinnati).

1. Testudo, tortoise, turtle.

2. Rana, frog, toad.

3. Draco, dragon.

4. Lacerta, lizards, crocodiles, chameleon,

newt, salamander, iguana, &c.

II. Serpentia. No external organs of motion; body
of an elongated form, covered with scales,
plates, or rings. Their slender, and for the
most part cloven tongue serves them for tast-
ing. Many are provided with an active ve-
nom, contained in little bags on the front of the
upper jaw, secreted by particular glands, and
conveyed into the wound made in biting by

XXX INTRODUCTION.

means of isolated teeth, which are tubular, with
a longitudinal opening at the top. They are
oviparous, but the egg is sometimes hatched in
the oviduct. Both jaws moveable.

1. Crotalus^ rattle-snake.

2. Boa. Immense serpents of India and

Africa.

3. Coluber, viper.

4. Anguis, blind-worm.

5. Amphisbcena.

6. CcBcilia.

Fishes respire by means of organs in the shape of
combs, placed at the two sides of the neck, between
which they force water to pass. They have, conse-
quently, neither trachea, larynx, nor voice. The
body is formed for swimming. Besides the four
fiös, which correspond to the limbs, they have ver-
tical ones upon the back, under the tail, and at its
extremity ; but they are sometimes wanting.

The nostrils are not employed in respiration.
The ear is quite hid within the cranium. The skin
is naked, or covered with scales. The tongue
is osseous. Both jaws are moveable. There are
often coeca in place of the pancreas. There is a
bladder and two ovaria.*

* The class of Fishes include the Fishes and the Amphibia Nantes
of LmNä;us.

INTRODUCTION. XXXI

The animals destitute of vertebrae have less in
common, and form a less regular series than the ver-
tebrated animals. But, when they have hard parts,
these are generally placed on the outside of the
body, at least when articulated ; and the nervous
system has not its middle part inclosed within a ca-
nal of bone, but loosely situated in the same cavity
with the other viscera.

The brain is the only part of the nervous system
which is placed above the alimentary canal. It
sends out two branches, which encircle the oesopha-
gus like a necklace, and which afterwards unite and
form the common fasciculus of the nerves.

None of the animals without vertebrae respire by
cellular lungs, and none of them have a voice.
Their jaws are placed in all kinds of directions, and
many of them have only organs of suction. None
of them have kidneys, or secrete urine. Those
among them which have articulated members have
always six at least.

(A) Cartilaginous Fishes.

Order I. Chondropterygii ; have no branchial
operculum, and, in most, the mouth is placed
on the under side of the head.

1. Petromyzon, lamprey.

2. Gaslrohranchus^ hag-fish.

3. Raitty ray, skate, torpedo, stingray.

XXXll INTRODUCTION.

4. Squalus, shark, saw-fish.

5. Lophius, sea-devil, frog-fish.

6. SalisteSy file-fish.

7. ChimcEra, sea-ape.

If. Branchiostegi, with opercula to the gills.

1. Accipenser, sturgeon, beluga.

2. Ostracio7i, truuk-fish.

3. Tetrodon, globe-fish.

4. Diodon, porcupine-fish.

5. Cyclopterus^ liimpsucker.

6. Centriscus, snipe-fish.

7. Syngnathus, pipe-fish.

8. Pegasus, sea-dragon.

(B) Bony Fishes, divided according to the situa-
tion of their fins.

Order I. Apodes, without ventral fins.

1. MurcBna, eel-kind.

2. Gymnotus, electrical eel.

3. Trichiurus.

4. Anarrhichus^ sea-wolf.

5. Ammodites, launce.

6. Ophidium.

7. Stromateus.

8. Xiphias, sword-fish.

9. Leptocephalus.

INTRODUCTION. XXXÜJ

II. JuGULARES. Ventral fins in front of the thoracic.

1. Callionymus, dragonet.

2. IJranoscopus, star-gazer.
S. Trachinus, sting-fish.

4. Gadtis, haddock, cod^ whiting, ling.

5. Ulennius, eel-pout.

III. Thoraoici. Ventral fins directly under the
thoracic.

1. Cepola, ribbon-fish.

2. Echeneis, sucking fish.

3. Coryphcena, dorado.

4. Gobius, gudgeon.

5. Cottus, P<^og^'

6. Scorpcena,

7. Zeus, dory.

8. Pleuronectes, flounder, plaice, dab, hali-

but, sole, turbot.

9. Chcetodon.

10. Sparus, gilthead, sea-bream.

11. Zjübrus, ramhow-üsh.

12. Sci6en€B.

13. Perca, perch.

J 4. Gasterosteus, stickleback.

15. Scomber, mackerel, bonito, tunny.

16. MuUus, mullet.

17. Trigla, flying-fish.

d

XXXIV INTRODUCTION.

IV. Abdominales. Ventral fins behind the tho-
racic ; chiefly inhabit fresh water.

J. Cohitis, loach.

2. Silurus.

3. LiOncaria, harness-fish.

4. Salmo, salmon, trout, smelt.

5. Fistularia.

6. Esox, pike.

7. Polypterus.

8. Elops.

9. Argentina.

10. Atherina.

11. Mugil

12. Exoccetus.

13. Polynemus.

14. Clupea, herring, sprat, shad.

15. Cyprinus, carp, tench, gold-fish, minnow,

&c. &c.

The inveitebral animals were distributed by LiN-
N^us into two classes, insects and worms (vermes).
The anatomical structure of these animals was very
imperfectly known when the Swedish naturalist first
promulgated his arrangement. But the labours of
subsequent zoologists, and particularly those of Cu-
viER, have succeeded in establishing such striking
and important diflferences in their formation, that a
subdivision of the Linnaean classes becomes indispen-

INTRODUCTION. XXXV

sably necessary. The insects of Linn^us are di-
vided into Crustacea and insecta; and the vermes of
the same author form three classes, viz. mollusca,
vermes, and zoophyta.

The Insects form the third class.

In their perfect state they have, like the Crus-
tacea, articulated limbs and antennae. Most of them
have also membranous wings, which enable them to
fly. All these last pass through several metamor-
phoses, in one of which they are quite destitute of
the power of motion. All of them have a nervous
system similar to that of the Crustacea ; but insects
have neither heart nor blood-vessels, and respire by
tracheas. Not only the liver, but all the secreting
organs are wanting, and their place is supplied by
long vessels, which float loosely in the abdomen.
The form of the intestinal canal is often very differ-
ent in the same individual, in its three different
states.*

The animals which resemble the larvce of insects,
and have, like them, the medullary cord knotted,
may be placed in the same class with insects, though
they undergo no metamorphosis ; but there are some
of that number which have distinct sanguiferous

* The class of Insects corresponds to the same class in the Systema
Naturae, with the exception of the two genera separated from it, in
order to form the class of Crustacea.

d 2

XXXvi INTRODUCTION.

vessels, and which must be arranged in a separate
class, intermediate between the mollusca, Crustacea,
and insects. To this class belong earth-worms and
leeches.

Order I. Coleoptera. Having a hollow horny case,
under which the wings are folded.

1. ScarahcBus, beetles.

2. Lucanus, stag-beetle.

3. Dermestes.

4. Ptinus.

5. Histur.

6. Gyrinus.

7. l^yrrhus,

8. Silpha, carrion beetle.

9. Cassida, tortoise beetle.

10. Coccinella, ladybird.

11. Chrysomela.

12. Hispa.

13. ßruchus, seed-beetle.

14. Curculio, weevil.

15. Attelahus, nut-beetle.

16. Ceramhyx,

17. Leptura.

18. Necydalis.

19. Lampyris, glow-worm.

20. Cantharis.

21. Elater, skipper.

INTRODUCTION. XXXVÜ

22. Cicindela.

23. l^uprestis.

24. Dyticus, water-beetle.

25. Carabus.

26. Tenebrio, meal-worm beetle.

27. Meloe, Spanish fly.

28. Mordella.

29. Staphylinus.

30. Forficula, earwig.

II. Hemiptera. Four wings, either stretched
straight out, or resting across each other.
Some are provided with jaws, others with a
proboscis, bent towards the abdomen.

i. Blatta, cockroach.

2. Mantis.

3. Gryllus, locust, grasshopper*

4. Fulgora, lantern-fly.

5. Cicada.

6. Notonecta.

7. JSepa, water scorpion.

8. Cimex, bug.

9. Aphis, plant louse.

10. Chermes.

11. Coccus.

12. Thrips.

XXXVm INTRODUCTION.

III. Lepidoptera. Soft hairy body, and four ex-
panded wings, covered with coloured scales.

1. Papilio, butterfly.

2. Sphinx, hawk moth.

3. PhalcBna, moth.

IV. Neuroptera. Four reticulated wings, glitter-
ing with colours of every kind.

1. Lihellula, dragon-fly.

2. Ephemera, day-fly.

3. Phryganea, water-moth.

4. Hemerobius.

5. Myrmeleon, ant-lion.

V. Hymenoptera. Generally possessing a sting,
and having four membranous wings.

1. Cynips.

2. Tenthredo.

3. Sir ex.

4. Ichneumon.

6. Sphex.

6. Chrysis, golden fly.

7. Vespa, wasp, hornet.

8. Apis, bee.

9. Formica, ant.

10. Termes, white ant.

INTRODUCTION. XXXIX

VI. DiPTERA. Two-winged insects, having two small
balances placed on the thorax behind the wings,
and generally covered with a little scale.

1. CEstrus, gad-fly.

2. Tipula, crane fly.

3. JKuscUy common fly.

4. Tabanus, gnat,

5. Culex, gnat, mosquito.

6. Empis.

7. Conops.

8. AsiluSy hornet fly.

9. Hippohosca, horse-leech.

VII. Aptera. No wings.

1. Lepisma, sugar-mite.

2. Produra, springtail.

3. Pediculus, louse.

4. Pulex, flea.

5. Acarus, tick, mite.

6. Hydrachna.

7. Phalarigium, shepherd.

8. Aranea, spider.

9. Scorpio, scorpion.

10. Cancer, crab.

11. Monoculus, horse-shoe fisch.

12. Oniscus,

13. Scolopendra.

14. Julus, centipede.

Xl INTRODUCTION.

The Vermes may be divided into two orders ; the
intestmal, which inhabit the bodies of other animals ;
and the external .

The former are not of such a complicated organi-
zation as the latter; so that they are sometimes ar-
ranged auiong the zoo)3hytes. The external worms
have a nervous chord possessing ganglia, an elon-
gated body composed of rings ; and having no dis-
tinct head. There are no members. Circulating ves-
sels, but no heart. No nerves have been discovered
in the intestinal worms.

The class oi worms comprehends some of the ge-
nera arranged by LinnjEUs among the vermes intes-
tina, such as the lumhricus, gordius, thrudo ; some
of the genera placed by the same naturahst among
\\\e vermes moUusca, sucli as the ap/irodita, nereis, te-
rebella, and lastly some genera included in his order
oi vermes testacea, such as the serpula dentalium.

Order I. Intestina.

1. Gordius, hair-worm.

2. Ascaris, thread- worm, round- worm.

3. Tricliocephalus.

4. Echinorhynchus.

5. JLumbricus, earth-worm.

6. Fasciola, fluke.

7. Tcenia, tape-worm.

8. Hydalis, hydatid.

INTRODUCTION. xH

.0. Sipunculus.
10. Jlirucio, lc'(.(:}j.

Tli(i class of vnollusca comprehends the greater
])art oflln; animals which I.inn.i:u,s has arranged in
the two orders of molluscu and leslacea, in tlie class
of vermes ; such as the sepia, Umax, ascidia, helix, os-
irea, patella, pholas, lereilo, &;c.

The body of the mollusca is fleshy, soft, and with-
out articulated memh<Ms, though sometimes contain-
ing hard parts int<nnally, and sometimes covered
completely by hard sIhjIIs. I'liey have arterial and
venous vessels, witliin whicli the blood undergoes a
true circulation.

They respire by branciiia). I'he brain is a distinct
mass, from which the nerves and medulla oblongata
proceed. There are ganglia in different parts of the
body.

'V\ni internal senses vary as to their number.
Some of th<; nudlusca have the organs of sight and
hearing (piite distinct, while others seem to be con-
fined to the senses of touch and taste. Many of
them can masticate their food ; others have the power
of swallowing only.

They have a very large liver, which affords a great
quantity of bile. The organs of generation vary ex-
tremelv.

Xlii INTRODUCTION.

II. Mollusca.

1. JLimax, slug.

2. Aplysia.

3. Doris.

4. Glaucus.

5. Aphrodita, sea-mouse.

6. Amphitrite.

7. Nereis.

8. iVa?>.

9. Ascidia.

10. Actinia.

11. Te%5.

12. Holothuria.

13. Thalia.

14. Terehella.

15. Lerncea.

16. Scyllcea.

17. (7/20.

18. Sepia, cuttle-fish.

19. Medusa, sea- blubber.

III. Testacea. These animals very much resemble
the worms of the preceding order.

1. Chiton.

2. Lepas, acorn-shell.

3. Pholas, pierce-stone.

4. iH/^«, muscle.

5. Solen, razor-shell.

INTRODUCTION.

6. Teilina.

7. Cardium, cockle.

8. Mactra.

9. Donax.

10. Ve7ius.

11. Spondylus.

12. Chama.

13. Area, ark.

14. Ostrea, oyster.

15. Anomia.

16. Mytilus, muscle.

17. Pinna, sea-wing.

18. Argonauta, paper-sailor.

19. Nautilus.

20. Conus.

21. CyprcBa.

22. Bulla, flipper.

23. Voluta, rhomb-shell.

24. Muccinum, whelk.

25. Strombus, screw.

26. Murex, rock-shell.

27. Trochus, top-shell.

28. Turbo, whirl-wreath.

29. Helix, snail.

30. Merita.

31. Haliotis, seB.-eair.

32. Patella, limpet.

33. Dentalium, tooth-shell.

xliii

xliv INTRODUCTION.

34. Serpula, worm-shell.

35. Teredo.

IV. Crustacea.

The body is covered with a hard crust in separate
pieces. There are articulated limbs, which are often
very nunierous. The nervous system consists of a
long, knotted cord, from the ganglia of which pro-
ceed all the nerves.

The eyes are compound, hard, moveable. The
ears are very imperfect. For the sense of touch, the
Crustacea have antennse and palpi, like insects. They
have a heart, arterial and venous vessels, and bran-
chiae for respiration. The jaws are transverse, strong,
and numerous. The stomach has teeth within. The
numerous ccEca afford a brown liquor, which seems
to be in the place of bile. The penis is double, and
there are two ovaria.*

J. Echinus, sea-hedgehog.

2. Asterias, sea-stars.

3. Encrinus.

V. CORALLIA.

They inhabit certain immovable dwellings which,
in most cases, are of a stony consistence, and are
called corals.

* The Crustacea include the genus cancer and the genus monoculus

of LlNN^US.

INTRODUCTION. xlv

1 . Tubipora.

2. Madrepora.

3. Millepora,

4. Cellepora.

5. Isis.

6. Gorgonia.

7. Alcyonium, animal hydra.

8. Spongia.

9. Flustra.

10. Tuhularia.

1 1 . Corallina.

12. Sertularia.

13. Cellulai'ia.

VI. ZOOPHYTA.

The class of Zoophytes correspond to the Zoo-
phyta and lythopyta of Linnaeus, but also include
some of the vermes mollusca, such as the echinus^
asterias^ holothuria, actinia^ medusa^ together with
the genus sipunculus from the vermes intestina.

1. JPennatula.

2. Hydra.

3. Brachionus, blossom- polype.

4. Vorticella.

5. Furcularia, wheel-animal.

6. Vibrio.

7. Volvox.

8. Chaos.

Xlvi INTRODUCTION.

Outline of Cuvier's Classißcatio7i of Animals; with
Examples of Species helonging to each Division.

I. VERTEBRATA.

1. MAMMALIA.

Bimana, man.

Quadrumana, monkey, ape, lemur.

Cheiroptera, bat, colugo.

Insectivora, hedgehog, shrew, mole.

Plantigrada, bear, badger, glutton.

Digitigrada, dog, lion, cat, martin, weasel, otter.

Amphibia^ seal, walrus.

Marsupialia, opossum, kangaroo.

Rodentia, beaver, rat, squirrel, porcupine, horse.

Edentata, sloth, armadillo, ant-eater, pangolin.

Pachydermata, elephant, hog, rhinoceros, tapir,

horse.
Ruminantia, camel, musk, deer, giraffe, antelope,

goat, sheep, ox.
Cetacea, dolphin, whale.

2. AVES.

Accipitres, vulture, eagle, owl.

Passeres, thrush, swallow, lark, crow, sparrow, wren.
Scansores, woodpecker, cuckoo, toucan, parrot.
Gallince, peacock, pheasant, grouse, pigeon.
Grallce, plover, stork, snipe, ibis, flamingo.
Palmipedes, auk, grebe, gull, pelican, swan, duck.

INTRODUCTION. xlvÜ

3. REPTILIA.

Chelonia, tortoise, turtle.

Sauria, crocodile, lizard, chamelion.

Opiiidia, serpents, boa, viper.

Satrackia, frog, salamander, proteus, siren.

4. PISCES.

Chondropterygiiy lamprey, shark, ray, sturgeon.
Plectognathiy sun-fish, trunk-fish.
Lophohranchif pipe-fish, pegasus.
Malacopterygii, salmon, herring, pike, carp, silurus,

cod, sole, remora, eel.
Acanthopterygii, perch, mackerel, sword-fish.

II. MOLLUSCA.

Cephalopoda, sepia, nautilus.
Pteropoda, clio, hyalaea.
Gasteropoda, slug, snail, limpet.
Acephala, oyster, muscle, ascidia, pyrosoma.
Brachiopoda, lingula, terebratula.
Cirrhopoda, barnacle.

III. ARTICULATA.

1. ANNELIDES, Or VERMES.

TuhicolcB, serpula, sabella.
Dorsihranchi(B f nereis, aphrodite.
AbranchicE, earth-worm, leech.

xlviii INTRODUCTION.

2. CRUSTACEA.

Decapoda, crab, lobster, prawn.
Stomapoda, squill.
Amphipoda, gamniarus.
Isopoda, aselius.
Sranchiopoda, monoculus.

3. ARACHNIDA.

Pulmonalia, spider, scorpion.
Trachealia^ phalangium, mite.

4. IN SECT A.

Aptera, centipede, podura.
Coleoptera^ beetle, glow-worm.
Orthoptera, grasshopper, locust.
Hemiptera, fire-fly, aphis.
Neuroptera, dragon-fly, ephemera.
Hymenoptera, bee, wasp, ant.
Lepidoptera, butterfly, moth.
Hhipiptera, xenos, stylops.
Diptera, gnat, house-fly.

IV. ZOOPHYTA.

Echinodermata, starfish, echinus.

Entozoa, fluke, taenia, hydatid.

AcalephcB, actinia, medusa.

Polypi, hydra, coralline, pennatula, sponge.

Infusoria, brachionus, vibrio, proteus, monas.

TABLE OF CONTENTS.

COMPARATIVE OSTEOLOGY.
CHAP. I.

On the Bones of Animals in General ..... 1

CHAP. II.

On the Skeleton of Mammalia 7

CHAP. III.

On the Skeleton of Birds 56

CHAP. IV.

On the Skeleton of Amphibia 67

CHAP. V.

On the Skeleton of Fishes . 75

CHAP. VI.

On the CEsophagus and Stomach 79

In Mammalia 80

Birds 97

Amphibia 106

Fishes 107

Insects ib.

Vermes 110

e

CONTENTS.

CHAP. VII.

Page

On the Intestinal Canal 112

In Mammalia ..;..... ib.

Birds 117

Amphibia 118

Fishes 119

Insects 121

Vermes ib.

CHAP. VIII.

On the Liver, Spleen, and Omentum ..... 124

In MammaHa ib.

Birds 126

Amphibia 127

Fishes ib.

Insects 128

Vermes .............. 129

CHAP. IX.

On the Urinary Organs ......... 131

In Mammalia ib.

Birds 132

Amphibia ,,,... 133

Fishes ib.

CHAP. X.

On the External Integuments 134

In MammaUa 135

Birds . 139

Amphibia 140

Fishes 141

CHAP. XI.

On several peculiar Secretions ....... 144

In Mammalia -, ib.

CONTENTS. li

Page

In Birds 147

Amphibia 148

Fishes 150

Insects ib.

Vermes . 151

ON THE VITAL FUNCTIONS.

CHAP. XII.

On THE Heart and Blood-Vessels 155

In Mammalia . . ib.

Birds 158

Amphibia . . ib.

Fishes . ^ t • • 161

Insects . 162

Vermes ....,,.-' 163

CHAP. XIII.

On the Absorbing Vessels . . 171

In Mammalia . . ... . ...... . . . 172

Birds .173

Amphibia 174

Fishes . ... .... ib.

CHAP. XIV.

On the Organs of Respiration 175

In Mammalia ib.

Birds 176

Amphibia 180

Fishes 184

Insects 186

Vermes 188

Ei CONTENTS.

CHAP. XV.

Page

On the Organs of Voice ......... 190

In Mammalia ib.

Birds .............. 194

Amphibia 196

THE ANIMAL FUNCTIONS.

CHAP. XVI.

On the Brain and Nervous System in general . . 203

In Mammalia 210

Birds 2^7

Amphibia 236

Fishes • • • 242

Insects .... . . ... , . . . . 249

Vermes ib.

CHAP, XVII.

On the Organs of the Senses in general, and on

THAT OF the SeNSE OF ToUCH IN PARTICULAR . , . 258

In Mammalia 259

Birds 261

Amphibia 262

Fishes 263

Insects ... . . . . ib.

Vermes ib,

CHAP. XVIII.

On the Tongue ; 264

In Mammalia * . . . 265

Birds 267

Amphibia 268

Fishes 269

Insects 270

Vermes ib.

CONTENTS. liii

CHAP. XIX.

Page

On the Organ of Smelling 271

In Mammalia ib.

Birds 275

Amphibia 276

Fishes ib.

Insects ib.

Vermes . 277

CHAP, XX.

On the Organ of Hearing ......... 278

In Mammalia , ib.

Birds 283

Amphibia 284

Fishes 285

Insects 286

Vermes ib.

CHAP. XXI.

On the Eye • 287

In Mammalia 288

Birds 296

Amphibia 299

Fishes ib.

Insects 303

Vermes 305

CHAP. XXII.

On the Muscles 306

In Mammalia ib.

Birds , . i , 311

Amphibia , 312

Fishes 313

Insects ib.

Vermes 314

i^ CONTENTS.

THE GENERATIVE FUNCTIONS.
CHAP. XXIII.

Page

On THja Male Oi^gans of Generation 317

In IMamr-ialia . . . . , S22

Birds 328

Amphibia 329

Fishes 330

Insects 331

Vermes S32

CHAP. XXIV.

On the Female Organs of Generation .... 334!

In Mammalia 335

Birds . 349

Amphibia , . . . 353

Fishes ib.

Insects . 355

Vermes . ..... . • . • ib.

CHAP. XXV.

On the Fcetus of Mammalia, and the Organs with
WHICH it is connected 357

CHAP. XXVI.

On the Breasts and Teats of Mammalia . . . 365

CHAP. XXVII.

On the Incubated Egg 369

Explanation of the Plates ........ 375

COMPARATIVE OSTEOLOGY.

COMPARATIVE OSTEOLOGY.

CHAPTER I.

ON THE BONES OF ANIMALS IN GENERALi

§ 1. Red-blooded animals only possess a true skeleton ;* to
which their bones are connected, and on which the general
formjt as well as the greater or less flexibility of the body de-
pends. There are a few exceptions to the general rule, that all
the bones of an atiimal enter into the formation of its sJteletont
viz. the bone of the tongue, commonly called os hyoides ; the
bone of the penis in several mammalia ; the bony ring in the
sclerotica of birds ; the clavicular bones of some mammalia ;
to which instances may be added the whole anterior extre-
mity in such mammalia as possess no clavicles ; and the abdo-
minal fins of fishes, which correspond to the posterior extremi-
ties of other animals.

§ 2. The ordinary white:|: colour of the bones has several
gradations, which are sometimes observable in the different
parts of the same bone ; as in the grinding teeth of the ele-

* Parts of a really bony structure are found in a few insects and worms, viz. in
the stomach of the lobster, and other species of the g^enus cancer ; in the mouth of
the sea-hedgehog (echinus), &c These parts at least resemble true bones more
than that body, which is commonly called cuttlefish hone.

t See Galen's remarks on the resemblance between the ape and the human sub-
ject, in the 1st book of his Chef-d'oeuvre de Anatomicis Administrationibvs, tom. iv.
p. 26, Chartier's edition.

X The red tint, which the bones of animals receive in Consequence of madder
being mixed with the food, is observed by Ant. Misaud, in his Centurice Memora-
Iriliwn seu Arcantrrum omnia generis, p. 161. Cologne, 1572, 12mo, It is remark-
able that this well known experiment meets with very imperfect «uceess in cold-
blooded animals.

g ON THE BONES OF ANIMALS IN GENERAL.

phant ; a section of which, or of the tooth of any other
herbivorous animal, as the horse, ox, &c. shews that its sub-
stance contains parts differing considerably in appearance.
Besides the processes of enamel, which are intermingled
throughout with the bone, there are two kinds of osseous
structure of different colours. In some few genera the whole
bony structure is of a different colour ;* thus, in the garpike,
{esox belone) the bones are green ; and in some varieties of
the common fowl they approach to a black colour.t

§ 3. The structure of the bones is subject to still greater
variations ; which occur in the different bones of the same
skeleton, as well as in the whole skeleton of particular classes
and orders. Instances may be observed in the dry and brit-
tle texture of the air bones of birds ; in the long fibres which
appear on splitting the bones of the larger amphibia and
fishes ; in the peculiar tenacity and solidity of individual parts
in some cartilaginous fishes.

Ossification does not go on with equal rapidity in all animals, nor
in all the bones of the same animal. Thus, the ossification of the
internal ear of man, and other mammalia, is completed before any
other parts ; and the bone formed at this early period surpasses all
others in density, and in the proportional quantity of phosphate of
lime which it contains. In the cetacea, particularly the balcena and
physeier, (the black and white whales) this part acquires a density and
hardness equal to those of marble. Its section presents a homogene-
ous appearance, without the least vestige of fibres, cellular texture,
or vessels.

Bones are slow in their formation in proportion to the remoteness
of the period at which the growth of the animal is finished. The
skeleton remains constantly in a cartilaginous state in some animals ;
such as the shark, skate, sturgeon, and all those fishes which, from

* This has, however, been asserted without foundation of some animals : thus,
Nicholls, in his Compend. Anat, p. 7, says, that the amedabad finch (^fringilla
amandava) has yellow bones; and others have stated the same circumstance re-
specting the golden pheasant (phasianus pictus). I have dissected both these ani-
mals, and found the assertions to be incorrect.

t Abulfazel, the vizier of Akber the Great, has remarked this of the fowls at
Indore, and Neermul in Berar, in his classical work, Ayeen Ahbery, vol. ii. p. 72 ;
and Niebuhr has stated it of those at Persepolis. Travels, vol. ii, p. 12.

ON THE BONES OF ANIMALS IN GENERAL. S

this circumstance, have been denominated cartilaginous, or chon-
dropterygii. Although the bones of other fishes, of reptiles, and
serpents, acquire a greater hardness, they constantly remain more
flexible, and retain a larger proportion of gelatine in their structure,
than those of warm-blooded animals.

The bony texture of quadrupeds is not so fine and delicate as that
of man : it is particularly loose and coarse in the cetacea, where the
distinction of the fibres is very manifest, even on the external sur-
face. In the jaw and the ribs particularly, the fibres may be
loosened by maceration, and become very obvious.

The bones of birds consist of a thin, firm, elastic substance, formed
of layers apparently fastened on each other. They are almost uni-
versally hollow ; but their cavities, which never contain marrow, are
filled with air. This organization unites the advantages of lightness
and strength.

The bones of reptiles and fishes have a very homogeneous appear-
ance, the earthy matter and the gelatine appearing to be uniformly
mingled : this is more strikingly marked, as we approach to the car-
tilaginous fishes, where the gelatine predominates, and conceals the
earth.

Several animals have no medullary cavities even in their long
bones. This is the case with the celncea, the seal, and turtle.

The horn of the stag is a real bone, as appears both from its tex-
ture, and its component elements. Its outer part is hard, compact,
and fibrous ; the internal substance is reticulated, but very firm ;
and possesses neither cavities nor marrow. It is liable to precisely the
same diseases as other bones ; thus, we sometimes find exostoses
formed upon its surface by the extravasation of its calcareous mat-
ter, while in other instances, from a deficiency of this component
part, it is rendered light and porous.

The shells of the testaceous animals are formed of a calcareous
substance, which is sometimes laminated ; sometimes as hard and
dense as marble. This substance is mingled, as in other bones, with
a gelatinous matter, from which it may be separated by means of
acids. The earth is not disposed in fibres, or laminae, as in other
bones ; but is uniformly expanded through the animal substance.

The layers of the shell are formed successively, as the animal in-
creases in size. The exterior or smallest are formed first : others
are successively deposited on the inner surface of these ; each new
layer extending beyond the margin of the former one, so that the
shell, by every addition, increases in thickness and circumference.
Are these new layers formed by vessels existing in the shell itself, or
are they produced by exudation from the surface of the animal?
Reaumur broke the shell of snails, and found that no reproduction
took place, when he covered the exposed part of the animal's body ;
while the injury was quickly repaired, when no artificial obstacle im-
peded the effusion of fluids from the surface. This experiment
seem» to prove that the shell is formed by deposition from the body

B 2

4 ON THE BONES OF ANIMALS IN GENERAL.

of the animal ; but there is an argument equally strong in favour of
the existence of vessels in the shell itself. Between the two last
formed layers of the convex shell of the oyster, a considerable cavity
is found, filled with a fetid and bitter fluid, and communicating by a
particular opening with the internal parts of the body. — This must
be destroyed and reproduced whenever a new lamina is added ; and
we cannot understand how such processes can be effected without ar-
terial and absorbing vessels.

Crustaceous animals (crab, lobster, &c.) have a skeleton which sur-
rounds and contains their soft parts, and which serves at the same
time the purposes of a skin. When it has attained its perfect con-
sistence, it grows no more ; but as the soft parts still increase, the
shell separates, and is detached, being succeeded by a larger one.
This new covering is partly formed before the other separates ; it is
at first soft, sensible, and vascular ; but it speedily acquires a hard
consistence by the increased deposition of calcareous matter.

Some of the mollusca have hard parts in the interior of their body.
The common cuttlefish {sepia officinalis) has a white, firm, and calca-
reous mass, of an oval form, and slightly convex on its two surfaces,
commonly known by the name of the cuttlefish -bone, contained in the
substance of its body. It has no connexion with any soft part,
whence it appears completely as a foreign body : no vessel or nerve
can be perceived to enter it ; nor does it receive the attachment of
any tendon. In the calmar [sepia loligo) this body resembles horn
in its appearance ; it is transparent, hard, and brittle. Its form re-
sembles that of a leaf, except that it is larger ; and sometimes that of
a sword-blade. This structure must grow like shells, by the simple
addition of successive layers.

§ 4. Excepting the crown of the teeth, bones are univer-
sally covered with periosteum ; and for the most part they
contain marrow* internally ; which varies much in consistence,
being fluid in whales.

§ 5. Bones are formed by the ossification of original carti-
lages ; the teeth being again for the most part excepted.
Ossification commences earlier, and proceeds more rapidly in
viviparous, than in oviparous animals. This fact appears at
least from comparing the incubated bird with the foetus of
mammalia. It is well known, that the incubation of the chick
occupies twenty-one days. The commencement of ossifica-

* The erroneous opinion which Aristotle held, of the want of marrow in the
bones of the lion, does not require an express refutation. On that subject, as well
as on some other mistaken assertions, see R. Hener, Ajwlog, pro Vesalio adversm
Sylvium. Venet. 1555, 8vo. p. 27.

ON THE BONES OF ANIMALS IN GENERAL. 5

tion is not perceptible before the beginning of the ninth day ;
which corresponds with the seventeenth week of human preg-
nancy. In the human embryo the first points of ossification
may be discerned in the seventh or eighth week after concep-
tion, certainly not in the third or fourth week, as some anato-
mists have supposed. These facts shew how little confidence
can be placed in that remark of Haller's, which concludes his
otherwise masterly observations on the formation of the bones
in the incubated chick : Quce de pullorum ossibus demon-
stravimus, ea et'iam de aliis animantmm classibus vera erunt,
et de ipso demum homine : " What I have proved as to the
bones of the chick, will hold good with respect to those of
other classes of animals, and of man." Of the mammalia, it is
to be observed, that many points in the formation of the
bones are completed sooner in quadrupeds than in man. An
example occurs in the closure of the fontanelies. I have found
these openings of considerable size in young foetuses of the
J'erce and pecora, but could hardly discern any trace of them
at the time of birth ; nothing at least which could be com-
pared to their magnituc.e in a human foetus of nine months.
When we compare the pelvis, and the whole mechanism of
parturition in the woman, with those of the female quadruped,
the cause of this difference appears. We then discover why
the yielding and overlapping of the large bones of the cranium,
which is chiefly effected by the fontanelies, is only required to
facilitate the birth of the human foetvis.

Professor Florman, of Sund, however, denies altogether
the appearance of the fontanelies in the skulls of young ani-
mals, according to Weber s and Mohrs Natur-histor. Reise
durch einen Theil Schwedens, p. 35. But I have found them
in many of the digitata, as for instance in the new born lepus,
of very considerable size.

As chemical analysis has discovered some interesting differences
in the constituent ingredients of the hard parts of various animals,
it seems right to give a short account of them in the present place.

The bones and teeth of red-blooded animals consist chiefiy of
phosphate of lime, depo.sited in the interstices of an animal sub-
stance ; which, when freed from the earthy matter by the immersion

6 ON THE BONES OF ANIMALS IN GENERAL.

•of the bone in an acid, approaches in its consistence to cartilage.
This is completely dissolved by boiling in a close vessel, and is
thereby proved to consist of gelatine. A small quantity of carbonate
of lime is mixed with the phosphate ; and hence effervescence arises
when a bone or tooth is subjected to the action of acids.

The horn of the stag is bone, containing a large proportion of ge-
latine.

The bones of fishes contain phosphate of lime ; but the animal
substance exists in very large proportion, particularly in those which
are called cartilaginous, where it completely obscures the earthy
matter.

Carbonate and phosphate of lime, deposited on a cartilaginous
basis, which retains the form of the part, after the earthy matter has
been separated, constitute the external covering of the crustaceous
animals, (crab, lobster, &c.). The carbonate is in greatest quantity.

Carbonate of lime, with a small quantity of phosphate, forms the
earthy principle of the shell of the echinus.

The shells of the testacea are entirely composed of carbonate of
lime, united to a gelatinous substance. When immersed in acid, a
rapid effervescence ensues. Some of them, which are very hard in
their texture, and have an enamelled surface, contain so little animal
matter, that they are completely dissolved by acids, like the enamel
of the teeth. But others, which consist of what is called mother of
pearl, and are formed by successive strata, (e. g. the oyster, muscle,
&:c.) contain a much larger proportion. When these have been ma-
cerated in acid, a gelatinous substance remains, consisting of several
layers of membrane, arranged stratum super stratum.

It appears therefore, that phosphate of lime is the peculiar earth of
hone, and carbonate that of shell ; although no bone has been hitherto
discovered without a small admixture of the latter ingredient.
Hence, that singular production from the body of the cuttle-fish is
improperly called bone ; as it consists, like shells, of various mem-
branes, hardened by carbonate of lime, without any phosphate. See
*' Experiments and Observations on Shell and Bone," by C. Hatchett,
Esq. Philos. Trans. 1799.

The same excellent chemist has also found, that the zoophytes
consist of carbonate of lime joined in different instances to various
proportions of animal substance. Philos. Trans. 1800, Patt II.

CHAPTER IL

ON THE SKELETON OF MAMMALIA.

§ 6. The form of the different mammalia, particularly the
four-footed ones,* varies considerably ; and their skeletons
must be marked by corresponding differences. Yet these va-
rieties may be included, at least for the greatest part, under
the following peculiarities ; which serve to distinguish their
skeletons from those of birds.

The skeletons of mammaha Those of birds are distin-

possess ; guished by ;

1 . A skull with genuine su- 1 . A skull which has not
tures (at least with very few real sutures.;];

exceptions ; as perhaps the
elephant, and the duck-billed
animalj-f- ornithorhynchus).

2. Jaws furnished with 2. A bill without teeth,
teeth ; except the ant-eaters,

the manis, the duck-billed ani-
mal,§ the halcena (whale).

* Compare this chapter with Goethe's ingenious osteological view of the four-
footed animals, in the 1st vol. of his Morphologie, p. 165 ; and the instructive plates
of the skeletons of quadrupeds, of which I have given a sketch in my work on the
bones, to which may be also added what has most recently appeared on this subject in
Cuvier's Ossemens Fossiles, and the Treatise of Dr. Pander and Professor D'Alton.

t This is the case, at least, with my specimen : the cranium, destitute of sutures,
strikingly resembles that of a bird in this respect,

i This is meant to apply to adult birds ; for young individuals have at least sepa-
rate cranial bones, if they are not connected by real denticulated sutures. The bones
of the head in birds are joined either by the squamous kind of suture ; or by the
mere apposition of their margins, which species of union is termed harmonia ; but
they arc soon consolidated into a single piece.

§ The duck-billed animal has, however, according to Cuvier, two teeth situated
at the bottom of the moutli, without roots, with flat crowns, and composed like those
of the oricteropus, of small vertical tubes.

ON THE SKELETON OF MAMMALIA.

3. An immoveable upper
jaw.

4. An OS intermaxillare.
(For the probable excep-

tionSj see § 15.)

5. Two occipital condyles.

6. Seven cervical vertebrae ;
except the three-toed sloth,
and some cetacea,

7. Moveable dorsal verte-
bras.

8. A pelvis closed in front ;
except the ant-eaters; which
have it open ; and the cetacea,
which have none.

9. True clavicles in a few
genera only.

3. A moveable upper jaw :
There are some exceptions,

viz. the rhinoceros bird.

4. No OS intermaxillare.

5. A single occipital con-
dyle.

6. More than seven cervi-
cal vertebrae.

7. Dorsal vertebras little
moveable, and for the most
part motionless.

8. A pelvis open anteriorly.
Except the ostrich.

9. Clavicles constantly, and
almost as universally the fork-
like bone.*

§ 7. We shall first describe the cranium*f' of mammalia ;
since its structure most materially influences the whole animal
economy, from serving as a receptacle for the brain, most of
the organs of sense, and those of mastication J

* The rudiments of this bone are to be found in the cassowary and ostrich, see
§ 57.

t Compare the numerous plates of the skulls of many animals, of both warm-
blooded classes in the Atlas to Gall's and Spurzheira's Anat. du Syst. Nerveux, and in
Spix's CepJialogenesis, and the useful observations on the skull and other parts of the
skeleton in many quadrupeds in Dr. Neegaard's Beytr'dgen zur vergleichenden Ana-
tomie, &c. Gottingen, 1807-8, p. 91.

X J. P. Frank was perhaps the first to notice the analogy between the vertebrae
and skull, in the 11th volume of his Delectus Opusculorum Medicor. 1792, p. 8. In
ea semper opinione versatus sum quamcunque spinalis columncB vertebram pro parvo, eo-
demque iransverso, crmiio esse considerandum : " I have always been of opinion that
every vertebra of the spinal column is to be regarded as a small transverse cranium ;"
p,nd again, extrema et ex omnibus maxime conspicua, nohilissimaque vertebra, quam calva-

ON THE SKELETON OF MAMMALIA. 9

§ 8. The well known division of the bones of the head into
those of the cranium and of the face, is convenient for point-
ing out the remarkable proportions of relative magnitude in
the two divisions.* Compare, for instance, the skull of the
kangaroo (t/idelphis gigantea) with that of the opossum, (did.
marsupialis) or the skull of the dolphin {delphinus delphis)
with that of the white whale {physeter macrocephalus).

§ 9. The number of proper bones of the cranium is, on the
whole, the same as in the human subject. The os frontis,
however, in most of the horned animals, is composed of two
equal portions ; in many of these the two parietal bones are
consolidated into one, and in others they are united to the oc-
ciput. Some of the digitata have a peculiar flat bone situated
transvei'sely between the parietal and occipital bones. f

§ 10. As the forehead of man is peculiarly distinguished
by the beauty of its convex superficies, so is that of many of
the quadrumana, as the larger animals of the monkey tribe,
papio mormoji, &c. by the large flat triangular surface into
which it is compressed, and the sides of which converge from
the processus malares at the external angles of the orbits, ob-
liquely backwards, towards the crista occipitalis.^

riam appellamus; " the last and most conspicuous and moveable of all the vertebras,
isthat called the calvaria, or skull-cap." These views are further developed by Oleen
in his treatise Über die Bedeutung der Sch'ddelknocken, Jena, 1807 ; and Ulrich De
Sensu ac Signißcatione Ossium Capitis, speciatim de Capite Testudinis. Berlin, 1816.

* A profile view answers as well for this purpose as a view taken vertically. I
have explained the use of the latter, (which I call norma verticalis) in comparing the
national forms of human crania, in the 3rd edition of my work. De Generis humani
Varietate Kutivu, p. 203, and in -the 4th, Decas. Crani. divers. Gent. p. 12. See
also Wolt, H. Crull, de Cranio, ejusque ad Faciem ratione, Gronig. 1810, Spix ; and
Mr. Lawrence's excellent Lectures un Physiology, Lond. 1819.

t See IMerrem's anatomy of the domestic mouse, in his Miscellaneous Observations
oil Natural Histin-y, and Meyer's Prodromus Anat. Wlurium, who calls it os transver-
sum: particularly Gotthelf Fischer's treatise De Osse Epactali, sen Gothiano Palmi-
gradorum, W squa , 1811. Some excellent observations on the developement of this
bone, and on that of the os occipitis in many of the mammalia are to be found in
Meckel's Handbuch der Pathologische Anatomie, vol. i. p. 326.

t In the horrid-looking skull, which 1 possess in my collection, of a person
thirty years of age, and idiotic from birth, and which I have described in the
Ccrtmenlutifl de Aiw,iiat.is et vitiosis quibusdam Nisus Formaiivi Ab^rrationibus, Gott.

IX) Otf THE SKELETON OF MAMMALIA.

The sphenoid bone is often divided into two parts in the qimd-
rumana ; one of these forms the lesser alse, and anterior clinoid
processes ; the greater alse, the posterior clinoid processes, and ba-
silar fossa, are formed by the other portion.

The two parietal bones form a single piece in the bat- kind. The
same circmnstance occurs in the Carnivora, in the pig, tapir, hippopo-
tamus, and horse.

The frontal and parietal bones of the elephant become consoli-
dated, at an early period, with all the other parts of the cranium ;
so as to form a bony cavity, in which no trace of sutures can be dis-
cerned. The parietal, occipital, and temporal bones are likewise
joined at an early period into one piece in the cetacea.

The pig, hippopotamus, tapir, horse, seal, walrus, and the rodentia,
have the os frontis divided by a middle suture into two portions.

That portion of the os temporis, which contains the tympanum, is
separated from the rest of the bone by a suture, which is seldom
completely united in the dog, cat, and civet. The cavity of the
tympanum is also sepai'ated in the rodentia, and the os frontis re-
mains divided into two portions. In the cetacea the parietal bones
are joined at a very early period to the occipital and temporal, so
that the five bones form only one. The bone of the ear is always
separated, and is merely attached to the cranium by soft parts. In
the elephant this bone is also distinct and separated from the tempo-
ral.

The cranium of the mammalia possesses the same fossae at its basis,
as are found in the human subject : they are however much shal-
lower ; and the eminences which define them are much less strongly
marked than in man. This difference is very perceptible even in
the simicE, where the cavities which hold the cerebellum are nearly on
a level with the middle fossae of the basis cranii ; and the sella
turcica is more superficial. The same fact is more strongly
marked as we arrive at those animals, whose general structure de-
viates more considerably from that of man. Those mammalia, which
have the occipital foramen situated at the back of the head, must
have the fossce cerebelli moved upwards ; hence, that margin of the
fossEe, which is posterior in man, passes across the upper part of the
back of the head in these animals.

The optic foramina of the elephant commence from one canal,
which receives the two optic nerves.

The foramen rotundum is sometimes absent, its place being sup-
plied by the spheno-orbitar fissure, (foramen lacerum) e, g. in the
elephant and horse. The foramen ovale is also frequently wanting ;
being included perhaps in the space left between the petrous por-

1813, p. 4, the animal expression is particularly given to it by the shape of the
forehead. This is of a triangular shape, and so compressed, that the upper edges of
the plana semicircularia for the attachment of the temporal muscles are scarcely a
thumb's breadth from each other.

ON THE SKELETON OF MAMItfALIA. 11

tion of the temporal bone, and the body of the sphenoid. This
latter opening does not exist in the genus simia, nor in the carni-
vorons mavnnalin, nor in the ruminavtia. It is on the contrary very
large in the elephant, and in some -^dentia.

The carotid canal does not exist in the rodentla ; but the artery
enters at the opening between the sphenoid and temporal bones.

The structure of the cranium presents a very remarkable singula-
rity in the elephant. Its two tables are separated from each other to
a considerable extent by numerous bony processes ; between which
are formed a vast number of cells, communicating with the throat by
means of the eustachian tubes, and filled with air, instead of the
bloody or medullary substance which occupies the diplöe of ani-
mals. The use of this structure in increasing the surface for attach-
ment of those large muscles which belong to the lower jaw, pro-
boscis, and neck ; and in augmenting the mechanical power of these
muscles by removing their attachments to a greater distance from
the centre of motion, has been very ingeniously explained by Camper,
{CEitvres, tom. ii.). These advantages are attained by the cellular
structure which we have just described, without augmenting the
weight of the head, and this precaution is particularly necessary in
the present instance, as the head is on other accounts more heavy and
massy in this than in any other animal. The air cells of birds in ge-
neral, and particularly those which pervade the cranium in the
ostrich, eagle, and owl, present examples of a similar formation, at-
tended with the same uses, viz. those of increasing the bulk and
strength of the bone, and diminishing its weight.

§ 11 . A principal variation in the form of the cranium arises
from the size and direction of the crista occipitalis, which
bears a determinate proportion to the strength of the jaws.
It is wanting in most monkeys, but is very large in the baboon
of Borneo.* The longitudinal crista is very strongly express-
ed in the badger ; and the transverse ridge is remarkable in
the beaver, and both in the opossvm. Between the arched
sides of the upper part of the cranium in the elephant lies a
broad and deep impression, with a small longitudinal crista*)' at
its bottom.

There is a considerable difference in this respect between
the various races of dogs : as between the pug-dog and that
of Newfoundland.

The crista occipitalis is a sharp, bony ridge, projecting from the

• See G. Fischer's Naturhistorische Fragmente, vol. i. tab. 3, 4.

t See Camj)er Descript, Anatomique d'un Elephant male, tab. 13, fig. 6,

1^ ON THE SKELETON OF MAMMALIA.

upper and back part of the cranium in mammalia, chiefly for the
attachment of the temporal muscle.

The size of the temporal fossa depends upon the magnitude of the
muscle which it contains. Hence it is larger in the Carnivora than
in any other order ; not only occupying the whole sides and upper
part of the cranium, but being still further increased by prominent
bony cristce, growing from the frontal, parietal, and occipital bones.
The two temporal muscles are indeed separated in many of these
animals merely by the parietal ridge, which would completely cover
the cranium.

These ridges are not so strongly marked in any animals as in the
Carnivora; yet they are discernible in most of the simioe. They occur
also in animals of the pitr kind, and in the other pac/n/derinata ; the
occipital crista is found where the others do not exist ; as it serves
for the attachment of the muscles of the neck.

% 12. The situation and direction of the great occipital fo-
ramen are attended with remarkable variations in some in-
stances. Instead of being situated far more anteriorly, and for
the most part horizontally, as in the human subject,* (in which
indeed the anterior margin is sometimes higher than the poste-
rior) it is placed, in most quadrupeds, at the base of the cra-
nium, and obliquely, with the posterior border more or less
turned upwards. In some, indeed, its direction is completely
vertical ; and in the marmot of the Alps its upper margin is
turned more forwards than the lower.*!*

* In the skull to which I have before alluded, this opening for the spinal marrow
lies much further back than in any of the numerous apes and baboons with which I
have compared it.

t See Daubenton, on the different Situation of the great Occipital Foramen in Man
and Animals, in the M^m. de rAcad. des Sc. de Paris, 1764, p. 568, On the dif-
ference, which we are now considering, this excellent zootomist founded his occipi-
tal line, which has been employed in the comparison of different crania with each
other. He draws two lines, which intersect each other in the profile of the skull :
one passes from the posterior margin of the great foramen, (which, in almost all
mammalia, is also the superior one,) through the lower edge of the orbit ; the other
takes the direction of the opening itself, beginning at its posterior edge, and touch-
ing the articular suiface of the condyles. He determines according to the angle
formed by the junction of these two lines, the similarity or diversity of the form of
crania.

This angle is, however, but an imperfect criterion ; for its variations are included
between 80° and 90° in almost all quadrupeds, which differ very essentially in other
points; and small variations occur in the individuals of one and the same genus.

ON THE SKELETON OF MAMMALIA. 13

The variations in the situation of the occipital foramen are impor-
tant, when viewed in connexion with the ordinary position of the
animal's body. In man, who is designed to hold his body erect,
this opening is nearly equi-distant from the anterior and posterior
extremities of the skull. The head, therefore, is supported in a state
of equilibrium on the vertebral column. The angle, formed by the
two lines mentioned by Daubenton, is only of three degrees.

Quadrupeds have the occipital foramen and condyles situated
farther back, in proportion as the face is elongated. That opening,
instead of being nearly parallel to the horizon, forms a considerable
angle with it ; which, measured accoi'ding to Daubenton, is of 90
degrees in the horse. The weight of the head in these anim.als is not
therefore sustained by the spine ; but by a ligament of immense
strength, which is either entirely deficient, or so weak, as to have its
existence disputed in the human subject. This ligumentum nuckce, or
cervical ligament, arises from the spines of the dorsal and cervical
vertebrae, (which are remarkably long for that purpose,) and is fixed
to the naiddle and posterior part of the occipital bone. It is of
great size and strength in all quadrupeds, but most particularly in
the elephant ; where the vast weight of the head, so much increased
by the enormous size of the tusks, sufficiently accounts for its in-
creased magnitude. It is bony in the mole, probably on account of
the use which the animal makes of its head, in disengaging and
throwing up the earth.

Animals of the genus simia and leimir hold a middle rank between
man, who is constantly erect, and quadrupeds, whose body is sup-
ported by four extremities. Their structure is by no means calcu-
lated, like that of man, for the constant maintenance of the erect
posture ; but they can support it with greater facility and for a
longer time than other animals. Hence, in the orang-outang, the
occipital foramen is only twice as far from the jaws as from the back
of the head, so that Daubenton's angle is only 37°. It is somewhat
larger in the other species of simice ; and measures 47° in the lemur.

§ 1.3. The true sutures, which connect the individual bones
of the cranium, are generally less intricate, at least to outward
appearance, in quadrupeds than in man. Their indentations
are very strong and sharp in the hotted pecora, for obvious
reasons ; and the frontal bones are thick in the same animals.
In sheep, affected with the staggers, where the hydatid is large,
and situated at the surface of the brain, I have found this part
of the bone almost completely absorbed ; so that it yielded to
pressure, and appeared like a thin cartilaginous membrane.
The ossicula wormiana are seldom seen in the crania of ani-
mals, yet I have specimens of these in the harCi and a young

14 ON THE SKELETON OP MAMMALIA.

orang-outang ; the sutures of the latter are remarkably ele-
gant. The observation, therefore, which Eustachius makes
{Ossium Examen, p. 173), concerning the sutures of apes,
namely, that " they are always so obscure, as scarcely ever
to deserve the name of sutures," must be understood with
some limitations.

§ 14. The general form of the cranium is most materially
influenced by the direction, and the various degrees of promi-
nence of the facial bones. The projection is generally formed
by a prolongation of the upper jaw ; partly also, and in many
instances chiefly, by the os intermaxillare, which is inclosed
between the two upper jaw-bones. To determine this with
greater precision. Camper instituted ihe facial line, the appli-
cation of which is most minutely explained in his posthumous
work, " On the Natural Differences of the Features," &c.
Like Daubenton, he draws on the profile of the cranium two
straight lines, which intersect each other ; but in different di-
rections from those of the French anatomist. A horizontal
line passes through the external auditory passage, and the
bottom of the cavity of the nose ; this is intersected by a more
perpendicular one, proceeding from the convexity of the fore-
head, to the most prominent point of the upper jaw, or of the
intermaxillary bone. The latter is the ^xo^ev facial line ; and
the angle, which it forms with the horizontal line, determines,
according to Camper, the differences of the crania of animals,
as well as the national physiognomy of the various races of
mankind.

I have mentioned my objections to its application, in the
latter point of view, in my work. De Generis Humani Variet.
Nativ. 3d edit. p. 200. Concerning its use, as applied to the
crania of animals, the same observations which were made on
the hne of Daubenton will hold good, mutatis mutandis.
About three-fourths of all the species of quadrupeds, which
we are hitherto acquainted with, whose crania differ extremely
in other respects, have one and the same facial line.

The two organs which occupy most of the face, are those of smell-
ing and tasting, (including those of mastication, &c.). In proportion,

ON THE SKELETON OF MAMMALIA. 15

as these parts are more developed, the size of the face, compared to
that of the cranium, is augmented. On the contrary, when the brain
is large, the volume of the cranium is increased in proportion to that
of the face. A large cranium and small face indicate therefore a
large brain, with inconsiderable organs of smelling, tasting, masti-
cating, &c. ; while a small cranium, with a large face, shew that
these proportions are reversed.

The nature and character of each animal must depend considerably
on the relative energy of its different functions. The brain is the
common centre of the nervous system. All our perceptions are
conveyed to this part, as a sensoriu??i commune : and this is the organ
by which the mind combines and compares these perceptions, and
draws inferences from them ; by which, in short, it reflects and
thinks. We shall find that animals partake in a greater degree of
this latter faculty, in proportion as the mass of medullary substance,
forming their brain, exceeds that which constitutes the rest of the
nervous system; or, in other words, in proportion as the organ of
the mind exceeds those of the senses. Since then, the relative pro-
portions of the cranium and face indicate also those of the brain,
and the two principal external organs, we shall not be surprised to
find that they point out to us, in great measure, the general charac-
ter of animals, the degree of instinct and docility which they possess.
Man combines by far the largest cranium with the smallest face;
and animals deviate from these relations in proportion as they in-
crease in stupidity and ferocity.

One of the most simple methods (though sometimes indeed insuffi-
cient,) of expressing the relative proportions of these parts, is by
means of the facial line, which has been already described. This
angle is most open, or approaches most nearly to a right angle in
the human subject ; it becomes constantly more acute, as we descend
in the scale, from man ; and in several birds, reptiles, and fishes,
it is lost altogether, as the cranium and face are completely on a
level. The idea of stupidity is associated, even by the vulgar, with
the elongation of the snout : hence the stupidity of the crane and
snipe has become proverbial. On the contrary, when the facial
line is elevated by any cause which does not increase the capacity of
the cranium, as in the elephant and owl, by the cells which separate
the two tables, the animal acquires a particular air of intelligence,
and gains the credit of qualities which he does not in reality possess.
Hence the latter animal has been selected as the emblem of the
goddess of wisdom. The invaluable remains of Grecian art shew
that the ancients were well acquainted with these circumstances ;
they were aware that an elevated facial line formed one of the grand
characters of beauty, and indicated a noble and generous nature.
Hence they have extended the facial angle to 90° in the representa-
tion of men on whom they wished to bestow an august character,
and in the representations of their gods and heroes they have even
carried it beyond a right angle, and made it 100°.

It must, however, be allowed, that the facial angle is of chief

16 ON THE SKELETON OF MAMMALIA.

importance in its application to the cranium of the human subject,
and of the quadrumuna ; as various circumstances affect the conclu-
sions which would result from employing it in other classes of mam-
malia. Thus in the carnivorous, and some of the ru7ninating animals,
in the pig, and particularly in the elephant, the great size of the fron-
tal sinuses produces an undue elevation of the facial line. In many
of the rodent ia, as the hare, &c., the nose occupies so large a space,
that the cranium is thrown quite back, and presents no point on a
front view, from which this line can be drawn.

The following are the angles formed by drawing a line along the
floor of the nostrils, and intersecting it by another, which touches
the anterior margin of the upper alveoli, and the convexity of the
cranium (whether the latter point be concealed by the face or not).

European infant 90°

adult

85
70
67
65

Adult negro . , . *

Orang-outang . . i . .
Long-tailed monkeys . . . ,

Baboons 40 to 30

Pole-cat 31

Pug dog 35

Mastiff; the line passing along the outer

surface of the skull .... 41

Ditto, inner ditto . . . . 30

Leopard ; inner surface ... 28

" Hare 30

Ram 30

Horse .23

Porpoise . . . . . . 25

In the 3d and 4th tables of Cuvier's Tableau Elementaire de VHis-
toire Naturelle, the crania of several mammalia are represented in
profile ; so as to afford a sufficient general notion of the varieties in
the facial angle. A similar comparative view, in one plate, is given
by White, in his account of the Regular Gradation, Sic, from the
work of Camper.

The mode of comparison instituted by Cuvier shews the relative
proportions of the cranium and face much more satisfactorily than
that of Camper, This learned naturalist makes a vertical section
of the skulls of different races of men, and the various classes of
animals, and then compares the relative proportion of the cavity of
the cranium to that of the section of the face. In the European the
area of the section of the cranium is four times as large as that of
the face ; the lower jaw not being included. The proportion of the
face is somewhat larger in the negro ; and it increases again in the
orang-outang. The area of the cranium is about double that of the
face in the monkeys ; in the baboons, and in most of the carnivorous
mammalia, the two parts are nearly equal. The face exceeds the cra-
nium in most of the other classes. Among the rodentia, the hare and

ON THE SKELETON OF MAMMALIA. 17

marmoi have it one-third larger ; in the porcupine, and the ruminanlia,
the area of the face is about double that of the cranium ; nearly tri-
ple in the hippopotamus, and almost four times as large in the horse.
In reptiles and fishes, the cranium forms a very inconsiderable por-
tion of the section of the head ; although it is considerably larger
than the brain which it contains.

The outline of the face, when viewed in such a section as we have
just mentioned, forms in the human subject a triangle, the longest side
of which is the line of junction between the cranium and face. This
extends obliquely backwards and downwards, from the root of the
nose towards the foramen occipitale. The front of the face, or the
anterior line of the triangle, is the shortest of the three. The face is
so much elongated, even in the siinice, that the line of junction of the
cranium and face is the shortest side of the triangle ; and the ante-
rior one the longest. These proportions become still more consi-
derable in other mammalia.

§ 15. The upper jaw-bones of other mammalia do not, as
in man, touch each other under the nose, and contain all the
upper teeth ; but they are separated by a peculiar single or
double intermaxillary bone,^ which is in a manner locked be-
tween the former, and holds the incisor teeth ■!• of such animals
as are provided with these teeth. It exists also in the pecora^
which have no incisor teeth in the upper jaw ; as well as in
such genera as have no incisor teeth at all, viz. the duck-
billed animal, the Cape ant-eater, and the armadillo. It is
even found in those mammalia which are wholly destitute of
teeth, as the ant-eater and the proper whates.% It is joined
to the neighbouring bones by sutures, which run externally by
the side of the nose and snout, and which pass, towards the
palate, close to the foramina incisiva.§ Its form and magni-

* Gotth. Fischer on the different forms of the intermaxillary bone in different ani-
mals, with plates. Leipzig, 1800, 8VO.3 and Kool's Annotationes Anatomicce. Gronig.
1800, p. 5.

t Vesalius De c. h. fahrica, p. 46, fig. 1.

J On this account I prefer the term intermaxillary bone to that of os incisivum,
which is employed by Haller, Blair, in his excellent account of the anatomy of
the elephant, calls it os patati ; and Vitet os maiilluire Interieur.

§ In human crania, at least those of the foetus and young children, there is at
the same part a small transverse slit near the foramen incisivum, of which Fallopius
gave the following accurate account in the year 1561 : Reperio hanc divisionem vel
rimurn jiotiui esse, quam uUuram ; cum as ah osse non separet, neque in exierurribus ap-
jjuriul, vel cum oj cum osae non conjungat, quod suturarum murius est. " I find this tg

C

18 ON THE SKELETON OF MAMMALIA.

tude vary surprisingly in several orders and genera of mam-
malia. It is small in many ferae, as also in the walrus {tri-
chechus). In many of the glires* it is remarkably large, viz.
in the beaver and marmot. It is also large in the hippopo-
tamus, porpoise, and cachalot, {physeter macrocephalus) and
particularly projecting in the wombat. Its form is very re-
markable in the ornithorhynchus, where it consists of two
hook-like pieces, joined by a broad synchondrosis."}*

The want of the os intermaxillare has been regarded as a chief
characteristic of the human subject; as one of the leading circum-
stances which distinguish man from other mammalia. That this
bone is really wanting in man must be allowed, notwithstanding the
doubts of Vicq d'Azyr. The well-known transverse slit, behind
the alveoli of the incisors in the human foetus, would form a very
slight and remote analogy between the human structure and that of
animals ; and when we consider, that the superior or facial surface
of the maxillary bones, so far from being marked by any suture,

be rather a division or fissure than a suture, since it does not separate one bone from
the other, nor does it appear exteriorly, nor join two bones, which is the office of
sutures." Obs, Anat, How far the alveolar portion of the superior maxillary bones
marked by the fissure between them may be regarded as a rudiment of an inter-
maxillary bone, has been ably shewn by Göthe, in the 1st vol. of his Morphologie.
Compare Vicq d'Azyr. Mtm, de I'Acad. des Sc. 1780, and Const. Nicati de Labii
leporini congeniti Natura et Origine. Ultraj. p. 25.

In the celebrated dispute of the 16th century, whether Galen's osteology was de~
rived from the skeleton of man or the ape, Ingrassias argued for the latter side of
the question, from Galen's having ascribed an intermaxillary bone to the human
subject : and the same author, in his classical Commentarii in Galeni Librum de
Ossibus, Panorra, 1603, fol. particularly points out the parts " where Galen, led
astray by the dissection of apes, deviates from the true construction of the human
body.''

* Its great size in these animals is accounted fot by the magnitude of the incisor
teeth which it contains.

t I cannot repeat here what I have observed in my book De Generis Huma. Var.
Nat. on the subject of the intermaxillary bone ; of which, as is there stated, not the
least trace could be discovered in the crania of some apes and baboons, although the
individuals were young. It must be inferred, that in these instances, it was conso-
lidated to the neighbouring bones in their foetal state, when all the other sutures
were nevertheless in a state of perfection.

Fischer could discover no trace of this bone in several mammalia of other orders,
viz. the three-toed sloth, (bradypiis tridactylus) and the horse-shoe bat, (yespertilio fer-
rurn equinum). See his work above quoted, and Geoff. Hilaire, in his Description
de I'Egypte, who found no trace of the intermaxillary bone in the vespertilio per-
J'oratus.

ON THE SKELETON OF MAMMALIA. 19

does not even bear a slit like that of the inferior part, it must be put
entirely out of the question.

That all other mammalia possess this bone, is not quite so clear
as that it is wanting in man. The exceptions occur in the quadru-
mana. In addition to those which the author has stated, it may be
observed, that the head of an crang-oulang, in the Hunterian Museum,
which possesses all the other sutures, wants those which separate
the intermaxillary bone. Tyson did not find this bone in his spe-
cimen of the animal, which was very young, (see his Anatomy of the
Pigmy) and it did not exist in a cranium which was delineated by
Daubenton. I have also seen the crania of other monkeys, in whicli
the sutures were all perfect and distinct, although this bone was
wanting.

^16. The above-mentioned anterior palatine holes, or fora-
mina incisiva are double in most mammalia, as in man. They
are much larger in quadrupeds than in the human subject :
in the pecora and the hare they are remarkably long and
broad.*

§ 17. There are remarkable impressions on the outer side of
the upper jaw o^ most pecora, near to the nasal bones, arising
from the situation of the sinus sebacei. This part has a
reticular structure in the hare, which approximates in that,
as well as in many other points, to the formation of the rumi-
nant animals.

§ 18. In the zygoma we observe several important diffe-
rences, immediately derived from the organs of mastication.i*
In many quadrupeds (especially the digitata and palmata,)
the processus malaris of the superior maxillary bone runs in a
long narrow process towards one similar in shape coming
from the temporal, so that it occupies the situation of the
malar bone in man. This bone is wedged in as a middle
piece between these two processes, has nothing to do with
the frontal, and consequently does not contribute to the for-
mation of the orbits. The zygoma is straight, and almost of

• In many instances, as in the lion, the openings of these large foramina are
very visible in the palate during life. See J. Ridinger's Delineaiion of the tame
Lion, which was exhibited in Germany in 1760, fol.

t See Pinel, Redierchcssur une Nouvelle Methode de Classification des Quadrupedes,
in the 1st vol. of the Actes de la f'ocitHi d'llisloire Naturelle de Paris,

c 2

20 ON THE SKELETON OF MAMMALIA.

a thread-like slenderness in the mole. It is of immense
strength, and includes a large space towards the cranium, for
lodging the powerful muscles which move the lower jaw, in
several carnivorous miimals, as the tiger, and in some glires,
as the beaver. In the rat, and some others, it is convex
below ; in the weasel, above. It is remarkable in the sloth
for a large descending process, which comes from the os
malae.*

The zygoma is wanting in the ant-eater, in which the temporal and
malar bones have only a slight projection instead of the visual zygo-
matic process. This circumstance is sufficiently explained by the
want of teeth, and the consequent want of mastication. The zygo-
matic suture is so oblique in the Carnivora, that the temporal bone
forms the whole superior margin, and the os malce the inferior edge
of the zygoma.

The zygoma may be arched both in the vertical and horizontal
directions. A curvature of the latter kind indicates the existence of
a strong temporal muscle ; while one of the former description shews
that the masseter is large. Both these curvatures are considerable
in the Carnivora.

§ 19. The elephant possesses only a rudiment of the nasal
bones. In most apes, and even in the orang-outang, there is
a single, triangular, and very small nasal bone; in the rib-
faced baboon {papio mormon) it is exceedingly long and nar-
row, and sinks between the long nasal processes of the superior
maxillary bones. In the greater number of true quadrupeds,
there are two ossa nasi, frequently of very considerable mag-
nitude. This is the case in the pecora and hare ; also in the
horse, pig, Sec. In the rhinoceros, the ossa nasi, which sup-
port the horn, are very soon consolidated together.

^ 20. Of the lacrymal bones also, {ossa unguis) there is
merely a rudiment in the elephant. These bones are stri-
kingly developed in the bisulca, especially in the antelope,
and still more remarkably in the opossum [didelphis marsu'
pialis).-f

* The two hedge-hogs (erinaceus setosus and ecaudatus) have indeed no malar
bone, see Meckel's Beyträge zur vergleichenden Anatomie, I. B. I. Heft, p. 40.

t A peculiarity in the makis (the lemur tribe) is that in them the superior open-
ing of the lacrymal duct lies external to the orbit j see Fischer's Anatmnie der
iHuki, I. B. Frankf. 1804, iv. p. Ö.

ON THE SKELETON OF MAMMALIA. 21

% 21. The orbits differ very much in their direction, capa-
city, and depth. They have for the most part a lateral direc-
tion. In the simice they are directed forwards, as in man ;
but they lie much more closely together than in the human
subject. In the beaver they point upwards.

They are completely closed in the quadrumanous mammalia.
In the pecora and solidungula they have a circular margin in
front ; but the external wall is deficient behind. In most of
ihefef^es, and in several glires, the outer part of their margin is
also deficient. The depth of these cavities is equally various.
In many cases they are so superficial as scarcely to deserve the
name of orbit ; viz. in the mole and ant-eater. Haller's asser-
tion, that man possesses a larger bony orbit than any animal,
is erroneous. The orbit of the cat is comparatively larger, as
also that of several maJcis (lemures). See the delineation of
their crania in Fischer's valuable work above quoted, Anatomy
a/the Maki. Frankfort, 1804, 4to.

The interval between the orbits is always smaller in the simise than
in the human subject. In several of these, as in the monkeys, pro-
perly so called, the two orbits are separated at their posterior part by
a simple bony septum. In other mammalia these cavities are thrown
towards the side of the head, and to a great distance from each other,
by the ascending or nasal processes of the upper jaw-bones, which
are very large.

In those mammalia, which have the orbit open at its outer and
back part, so as to communicate with the temporal fossa (such as the
Carnivora, rodentia, edentata, and pachydermata) the os malae merely
contributes to the formation of the zygoma, without being connected
to the frontal or sphenoid bones. The superior maxilla merely forms
the anterior border of the cavity, without constituting the floor of the
orbit, which is indeed open below. The ossa palati, which are large,
form a considerable share of the inner part of the cavity ; the ethmoid
bone not contributing to it.

The ru?mnating animals, as well as the horse and ass, have the mar-
gin of the orbit completed at its outer part by a bony circle, although
tlie cavity is open behind to the temporal fossa.

The mole has not, properly speaking, an orbit. Its diminutive eyes,
tlie very existence of which was for a long time questioned, lie under
the integuments. Blumenbach 's Beschreibung der Knocken, p. 225,
note. Tlie same observation holds good of the myrmecophaga didac-
tyla. Ibid.

The organ of vision is present without exception, only in one class
of animals, namely, in birds. In the mammalia we have two instances

22 ON THE SKELETON OF MAMMALIA.

of complete blindness, namely, in the blind rat (spalax typhlus, Pall.
Mus tj/pklus, L.) and in a variety of the mole (chrysochlorus, sorex
aureus). In both these animals a hairy curtain, in which there is no
fissure, is continued over the shrivelled eyes. Rudolphi, Physiologie,
vol. ii. p. 154.

§ 22. In mammalia which have horns, these parts grow-
on particular processes of certain bones of the cranium. In the
one-horned rhinoceros they adhere to a rough, and slightly
elevated surface of the vast nasal bone. The front horn of the
two-horned species has a similar attachment ; the posterior
rests on the os frontis ;* as those of the horned pecora do.
Two kinds of structure are observed in the latter : there are
either proper horns, as in the genera of the ox, goat, and an-
telope, or bony productions, as in the genus cervus, which in-
cludes animals of the deer kind. In the former, the external
table of the frontal bones is elongated into one process, and in
the oms polycerata, into several. In the greater number of
these the frontal sinusses extend into the horny processes.
The antelopes have been in general excepted. But that this
exception does not hold good of all the species of this tribe,
appears from the horn of an antelope bubalis in my collection,
the bony process of which is hollow and connected with the
frontal sinusses. The external vascular surface of the pro-
cess secretes the horn, which covers it like a sheath. In
the stag kind (in the male only in most genera), the frontal
bone forms a short flattened prominence, from which the pro-
j)er antler immediately shoots forth. It is renewed every year,
and is covered, during the time of its growth, with a hairy and
very vascular skin. The little horns of the giraffe hold a
middle place between these two divisions. In their form,
structure, and permanent duration, they resemble the frontal
processes of the proper horns: in their hairy covering they
approach to the branches of the stag kind.*f-

* GeofFroy, in M6moires de la Sociitt d'Histoire Naturelle de Paris, an 7. cahier 1.

t Anomalous instances, in which the females have possessed horns, may be seen
in Stahl De Cornu Cervi deciduo, Hal. 1699. Leopold, Diss, de Alee, Bas. 1700.
Hoy in the Linnean Trans, vol. ii. p. 356.

ON THE SKELETON OF MAMMALIA. 23

I have collected about twenty instances, from the mid-
dle of the sixteenth century downwards, in which horned
hares are said to have been found, with small branches like
those of the roebuck, both in different parts of Europe,
and in the East Indies. Were this fact ascertained, it would
furnish another striking point in which these animals resem-
ble the pecora. The fact is suspicious, because I have not
yet been sufficiently satisfied of a single instance in which
the horns were on the hare's head, although every trouble has
been taken to procure information ; and they appear in the
drawings, which I possess, by far too large for a hare.

The annual reproduction of horns constitutes, in many points
of view, one of the most remarkable phenomena of animal phy-
siology. It affords a most striking proof, 1 st, of the power of
the nutritive process, and of the rapid growth which results
from this process in warm-blooded animals ; for the horn of a
stag, which may weigh a quarter of a cwt. is completely form-
ed in ten weeks : Sndly, of the remarkable power of absorption,
by which, towards the time of shedding the old horn, a com-
plete separation is effected of the substance, which was before
so firmly united with the frontal bone : Srdly, of a limited du-
ration of life in a part of an animal, entirely independent on
the life of the whole animal, which in the stag extends to about
thirty years : 4thly, of change of calibre in particular vessels ;
for the branches of the external carotid, which supply the
horn, are surprisingly dilated during its growth ; and recover
their former dimensions when that process has ceased : 5thly,
of a peculiar sympathy, which is manifested between the growth
of the horns and the generative functions ; for castration, or
any essential injury of the organs of generation, impedes the
growth, alters the form, or interrupts the renewal of the
horns.* It has also been asserted, but without a sufficient

• See Russell's experiments in his Economy of Nature in Acute and Chronical
Diseases of the Glands : Berlin Soc. of Inquirers into Nature, vol. iv. p. 360, and
Dr. Paris, in the Transac, of the Linnean Society, vol. x, part II. p. 211.

S4 ON THE SKELETON OF MAMMALIA.

proof hitherto, that injuries of the newly formed horn render
the stag impotent for some time.

The word horn, which is frequently applied in English to the ant-
lers oi the deer kind, as well as to the real horns of other genera,
would lead to very erroneous notions on this subject. The antler is
a real bone ; it is formed in the same manner, and consists of the same
elements as other bones ; its structure is also the same.

It adheres to the frontal bone by its basis ; and the substance of
the two parts being consolidated together, no distinction can be traced,
when the antler is completely organized. But the skin of the forehead
terminates at its basis, which is marked by an irregular projecting
bony circle ; and there is neither skin nor periosteum on the rest of
it. The time of its remaining on the head is one year : as the period
of its fall approaches, a reddish mark of separation is observed be-
tween the process of the frontal bone and the antler. This becomes
more and more distinctly marked, until the connexion is entirely de-
stroyed.

The skin of the forehead extends over the process of the frontal
bone, when the antler has fallen : at the period of its regeneration, a
tubercle arises froin this process, and takes the form of the future
antler, being still covered by a prolongation of the skin. The struc-
ture of the part at this time is soft and cartilaginous ; it is immedi-
ately invested by a true periosteum, containing large and numerous
vessels, which penetrate the cartilage in every direction, and by the
gradual deposition of ossific matter, convert it into a perfect bone.

The vessels pass through openings in the projecting bony circle at
the base of the antler ; the formation of this part, proceeding in the
same ratio with that of the rest, these openings are contracted, and
the vessels are thereby pressed, until a complete obstruction ensues.
The skin and periosteum then perish, become dry and fall off; the
surface of the antler remaining uncovered. At the stated period it
falls off, to be again produced, always increasing in size.

The horn is shed in the spring, and re-produced in the summer ;
during the interval the male and female abstain from copulation.
When the rutting season, which lasts three weeks, commences, large
troops of the males and females re -assemble, and continue together
during the winter.

§ 23. The skeleton of quadrupeds deviates more from that
of man in the form of the lower jaw-bone, than in any other
part. This difference consists chiefly in the want of a prominent
chin ; that peculiar characteristic of the human countenance,
which exists in every race of mankind, and is found in no other
instance whatever. Man has also the shortest lower jaw in
comparison with the cranium ; the elephant perhaps approach-

ON THE SKELETON OF MAMMALIA. 25

ing the nearest to him in this respect.* The same bone is fur-
ther distinguished by the peculiar form and direction of its
condyle. The articulation of these processes varies according
to the structure of the masticating organs. They are both si-
tuated in the same straight horizontal line in the ferm ; their
form is cylindrical ; and they are completely locked in an elon-
gated glenoid cavity, whose margins are so extended before
and behind the condyle, that all rotatory motions ai'e rendered
impossible, and hinge-like movements only allowed. This
structure is most strikingly exemplified in the badger, where
the cylindrical condyles are so closely embraced by the mar-
gins of the articular cavity, that the lower jaw (at least in the
adult animal), is still retained in its situation, after the soft
parts have been entirely removed by maceration. In many
herbivorous animals (in the most extensive sense of the term)
these condyles are really rounded eminences ; viz. in the ele-
phant and beaver. Their surface is flattened in the pecora,
which have also the lower jaw narrower than the upper, so
that the two sets of teeth do not meet together, when the
mouth is shut, but are brought into contact by the free
lateral motion, which takes place in rumination. The two con-
dyles lie parallel to each other in a longitudinal direction in
maxxy gUres ; viz. in the hare, where (as in the ant-eater) the
coronoid process is almost entirely wanting. This process is
on the contrary very conspicuous in the giraffe. The cetacea
have the articular surface of the lower jaw turned almost di-
rectly backwards.i*

There are, on the whole, few other bones in the skeleton of
mammaha, of such various forms as the lower jaw. The most
anomalous formation of this bone is the shovel-like surface of
its anterior part in the ducJc-billed animal : to which may be

* See Pinel Sur les Os de la Tete de VElephaiU in the Journal de Physique, torn,
xliii. p. 54.

t The singular, but very common error, of considering the halves of the lower
jaw of the whale as ribs has been already refuted by Rondelet, De Piscibvs, p. 53.

26 ON THE SKELETON OP MAMMALIA.

added the very strong hoviaontal processes on the under side
of the lower jaw in the wombat, and the strikingly large late-
ral portions of this bone in the Brazilian monlceys (cercopithe-
cus seniculus and Behebub) between which the bony cavity of
the larynx is situated, which enables them to emit a peculiar
deafening sound.

We have lastly to observe that the two halves of the lower
jaw are connected throughout life, in many mammalia, by a
mere synchondrosis ; which is easily separated by boiling or
maceration. This is the case in vuBxiyfercB, glires, and cetacea.
They are consolidated into one piece, as in the human subject,
at an early period, in the quadrumana, as also in the horsey
horned cattle^ pig, elephant, &c.

As the motions of the lower jaw must be materially influenced by
the form of its condyle, and by the manner in which that process is
connected to the articular cavity of the temporal bone ; we shall find,
as might have been expected, a close relation between these circum-
stances and the kind of food by which an animal is nourished. Thus
the lower jaw of the Carnivora can only move upwards and down-
wards, and is completely incapable of that horizontal motion which
constitutes genuine mastication. Hence these animals cut and tear
their food in a rude and coarse manner, and swallow it in large por-
tions, which are afterwards reduced by the solvent properties of the
gastric juice. Such mammalia, on the contrary, as live on vegeta-
bles, have, in addition to this motion, a power of moving the lower jaw
backwards and forwards, and to either side ; so as to produce a grind-
ing effect, which is necessary for bruising and triturating grass, and
for pulverising and comminuting grains. In all these, therefore, the
form of the condyle, and of its articular cavity, allows of free motion
in almost every direction. The teeth may be compared, in the
former case, to scissars ; in the latter, to the stones of a mill.

§ 24. The jaws of mammalia contain teeth* with a very few

* See J. G. Duverney, Lettre contenant plusieurs nouvelles Observations sur VOsteOf
logie, Paris, 1689, 4to.

J. J. Kober De Dentihus, eorumque Diversitate, Argent. 1774, 4to.

P. M. G. Broussonet, Comparaison entre les Dents de V Homme et Celles des Quad-
rupedes, in Mäm. de I' Acad, des Sc, de Paris, 1787.

Rob. Blake's Essay on the Structure and Formation of the Teeth in Man and va-
rious Animals, Dublin, 1801-8, and particularly Fr. Cuvier des Dents des Mammiferes,
Par. 1821-8.

ON THE SKELETON OF MAMMALIA. 27

exceptions: the proper whales, {balcence) the manis, (scaly
lizard) and the American ani-eaiers, are the only genera en-
thely destitute of these organs.

The substance and texture of the teeth are different from
those of all other bones. The enamel which covers the crown
of the tooth is characterized by its peculiar hardness (sparks
of fire may be produced by striking it against steel), as well as
by the want of animal matter, with which the bony part of the
crown as well as the fang of the tooth are copiously provided.
It seems to be wanting in the tusks of the elephant, as also in
those of the walrus, the narwhale, {mo7iodon, sea-unicorn) and in
the incisors of the African hog {sus Äthiopiens). Yet these
are all surrounded by an external thin coat of a different sub-
stance from the body of the tooth. These teeth have indeed
some peculiarity in their texture ; the ivory of the elephant's
tusks in particular is unlike any other substance. Not to mention
other peculiarities of ivory, which have induced some modern
naturalists to consider it as a species of horn, the difference
between its structure and that of the bone of teeth is evinced
in the remarkable pathological phenomenon, resulting from
balls, with which the animal has been shot when young, being
found on sawing through the tooth, imbedded in its substance
in a peculiar manner. Haller employed this fact, both to re-
fute Duhamel's opinion of the formation of bones by the pe-
riosteum, like that of wood by the bark of a tree ; as well as to
prove the constant renovation of the hard parts of the animal
machine. It is still more important, in explanation of that
" nutritio ultra vasa," which is particularly known through the
Petersburg prize dissertation. Instances of the fact above-
mentioned, in all which the balls were of iron, may be seen
in several writers.* I possess a similar specimen : but there
is a still more curious example in my collection, of a leaden
bullet contained in the tusk of an East Indian elephant, which

* Buffon, 4to. ed. torn, ii. p. 161, in Gallandat over de Olyphants Tanden in the
Verhandelingen der Genootfch, le Vlissingen, p. 352, torn. ix. ; and in Bonn's Descr.
ihetauri Hoiiani, p. 146. Goethe's Morphologie, vol. ii. p. 7 ; and Cuvier's Ossemens
Fossiles, torn. i. p. 48.

28 ON THE SKELETON OF MAMMALIA.

tusk must have been equal in size to a man's thigh, without
having been flattened. It lies close to the cavity of the tooth ;
its entrance from without is closed as it were by means of a
cicatrix ; and the ball itself is surrounded apparently by a pe-
culiar covering. The bony matter has been poured out on the
side of the cavity in a stalactitic form.

The organization of the molar teeth of the Cape ant-eaters
is perfectly anomalous ; they consist of vertical tubes. In some
animals the crowns of particular teeth are distinguished by
peculiar colours. The incisors of some glires, as the beaver^
marmot, and squirrel, are of a nut-brown colour on their ante-
rior surface, and the molar teeth of several bisulca, as well as
of the elephant, are covered by a very hard black substance
of a vitreous appearance. This black vitreous matter is some-
times covered with a crust of a metallic shining bronze colour;
particularly in the domesticated horned cattle, and sheep.*

The teeth of the human subject seem to be designed for the single
purpose of mastication ; and hence an erroneous conclusion might be
drawn, that they serve the same office in other animals. Many ex-
ceptions, however, must be made to this general rule. Some mam-
malia, which have teeth for the office of mastication, have others,
which can be only considered as weapons of offence and defence, as
the tusks in the elephant, liippopotamiis, toalrus, and manati. The large
and long canine teeth of the Carnivora, as the lion, tiger, dog, cat, &c.
not only serve as natural weapons to the animal, but enable it to seize
and hold its prey, and assist in the rude laceration which the food un-
dergoes previous to deglutition. The seal, the porpoise, and other
cetacea, as the cachalot [physeter 7}iacrocephalus) have all the teeth of
one and the same form ; and that obviously not calculated for masti-
cation. They can only assist in securing the prey, which forms the
animal's food.

Animals of the gen^is balcena (the proper whales') have, instead of
teeth, the peculiar substance called nhalebone, covering the palatine
surface of the upper jaw : this resembles in its composition, hair,
horn, and such substances.

The lower surface of the upper jaw forms two inclined planes,
which may be compared to the roof of a house reversed ; but the two
surfaces are concave. Both these are covered with plates of the
whalebone, placed across the jaws, and descending vertically into the
mouth. They are parallel to each other, and exist to the number of

* See Stobaeus De Inauratione spontanea, dentium quorundam animalium, in Act,
Liter. Suecic. vol, iii. p. 83, 1733.

ON THE SKELETON OF MAMMALIA. 29

two or three hundred on each of the surfaces. Tliey are connected to
the bone by the intervention of a white ligamentous substance, from
which they grow ; but their opposite edge, which is turned towards
the cavity of the mouth, has its texture loosened into a kind of fringe,
composed of long and slender fibres of the horny substance ; which
therefore covers the whole surface of the jaw. This structure proba-
bly serves the animal in retaining and confining the mollusca which
constitute its food.

The teeth of the ornithorhynchus paradoxus and hystrix deviate very
considerably from those of other mammalia. In the former animal
there is one on each side of the two jaws : it is oblong, flattened on
its surface, and consists of a horny substance adhering to the gum.
There are likewise two horny processes on the back of the tongue :
these point forwards, and are supposed by Sir Everard Home to pre-
vent the food from passing into the fauces, before it has been suffi-
ciently masticated. In the hystrix, there are six transverse rows of
pointed horny processes at the back of the palate ; and about twenty
similar horny teeth on the corresponding part of the tongue.

See Sir Everard Home in the Philos. Trans. 1800, part 2 ; 1802
parts 1 and 2.

The substance composing the tusks of the elephant, commonly
called ivory, is certainly different from the bone of other teeth. It is,
generally speaking, more hard and compact in its texture ; it is dis-
tinguished from all others by the curved lines which pass in different
directions from the centre of the tooth, and form, by their decussation,
a very regular arrangement of curvilinear lozenges. It soon turns
yellow from exposure to the air. The tusk of the hippopotamus is
harder and whiter ; and consequently preferred for the formation of
artificial teeth. In the walrus, the interior of the tooth is composed
of small round portions, placed irregularly in a substance of different
appearance, like the pebbles in the pudding stone ; and the molar
teeth have a similar structure.

The curious facts which Blumenbach has mentioned in this section
have been sometimes brought forward to prove the vascularity of the
teeth ; a doctrine which is refuted by every circumstance in the for-
mation, structui-e, and diseases of these organs. It may be first ob-
served, that the appearances exhibited by the teeth in question are
by no means what we should reasonably expect in such a case. When
a bullet has entered the substance of the body, the surrounding lace-
rated and contused parts do not grow to the metal, and become firmly
attached to its surface, but they inflame and suppurate in order to
get rid of the offending matter. If the ivory be vascular and sensi-
ble, why do not the same processes take place in it?

We can explain very satisfactorily how a bullet may enter the tusk
of an elephant, and become imbedded in the ivory without any open-
ing for its admission being perceptible. It will be hereafter shewn
that these tusks are constantly growing during the animal's life, by a
deposition of successive laminse within the cavity, while the outer
surface and the point arc gradually worn away ; and that the cavity

30 ON THE SKELETON OF MAMMALIA.

is filled for this purpose with a vascular pulp, similar to that on
which teeth are originally formed. If a ball penetrate the side of a
tuskj cross the cavity, and lodge in the slightest way on the opposite
side, it will become covered towards the cavity by the newly depo-
sited layers of ivory, while no opening will exist between it and the
surface, to account for its entrance. If it have only sufficient force to
enter, it will probably sink, by its own weight, between the pulp and
tooth, until it rests at the bottom of the cavity. It there becomes sur-
rounded by new layers of ivory ; and as the tusk is gradually worn
away, and supplied by new depositions, it will soon be found in the
centre of the solid part of the tooth, Lastly, a foreign body may
enter the tusk from above, as the plate of bone which forms its socket
is thin ; and if this descends to the lower part of the cavity, it may
become imbedded by the subsequent formations of ivory. This must
have happened in a case where a spear-head was found in an ele-
phant's tooth. The long axis of the foreign body corresponded to
that of the cavity. No opening for its admission could be discovered,
and it is very clear that no human strength could drive such a body
through the side of a tusk. Philos. Trans. 1801, part i.

§ 25. It is difficult to frame a classification of the teeth
which shall be generally applicable, and at the same time
intelligible. Their situation affords perhaps a more eligible
basis of arrangement than their form, since that is the same
throughout, in some instances, as in the cachalot and porpoise.
They may therefore be distributed into the three classes of
front teeth, corner teeth, and back teeth.

The front teeth are the incisores of Linnseus. The corner teeth
are the canini, laniarii, of Linnaeus; cuspidati of Hunter. The back
teeth are the molares. The term of tusks is applied to such teeth as
extend out of the cavity of the mouth.

§ 26. The front teeth in the upper jaw of quadrupeds and
dolphins are those which are implanted in the intermaxillary
bone; the front teeth in the lower jaw are such as correspond
to these, or to the anterior margin of the intermaxillary bone
in animals which have no upper incisors. Their number and
form vary considerably. In the glires their cutting edge is
formed like a chisel, particularly in the lower jaw, whence
Grew called them denies scalprarii. In some animals, as in
the leaver and the porcupine, the lower ones have remark-
ably long roots : in many, as in the marmot, the upper ones
also have long roots. In the hare there are two very small

ON THE SKELETON OF MAMMALIA. 31

teeth placed just behind the large ones. The crowns of the
front, as well as of the back teeth, form flat prominences in
the walrus. The front extremity of the lower jaw, with its
teeth, extends in the dolphin {delphiiius delpMs) much beyond
the corresponding part of the upper jaw, contrary to what
happens in other animals. The lower fore teeth of most mam-
malia have a more or less oblique position ; while in man they
are perpendicular. The orang-outang of Borneo is the only
animal which in this respect at all approaches to the human
subject.

The structure of the incisor teeth, in the rodentia, deserves atten-
tion on several accounts. They are covered by enamel only on their
anterior or convex surface, and the same circumstance holds good
with respect to the tusks of the hippopotamus. Hence, as the bone
wears down much faster than this harder covering, the end of the
tooth always constitutes a sharp cutting edge, which renders it very
deserving of the name of an incisor tooth.

This partial covering of enamel refutes, as Blake has observed
{Essay on the Structure, Sfc. of the Teeth, p. 212,) the opinion that the
enamel is formed by the process of crystallization.

The incisor teeth of these animals are used in cutting and gnawing
the harder vegetable substances ; for which their above-mentioned
sharp edge renders them particularly well adapted. Hence Cuvier
has arranged these animals in a particular order by the name of
rodentia, or the gnawers. As this employment subjects the teeth to
immense friction and mechanical attrition, they wear away very
rapidly, and would soori be consumed, if they did not possess a power
of growth, by which this loss is recompensed.

These teeth, which are very deeply imbedded in the jaw, are hol-
low internally, like a human tooth, which is not yet completely
formed. Their cavity is filled with a vascular pulp, similar to that
on which the bone of a tooth is formed ; this makes a constant
addition of new substance on the interior of the tooth, which ad-
vances to supply the part worn down. The covering of enamel
extends over that part of the tooth which is contained in the jaw, as
we might naturally expect : for this must be protruded at some
future period to supply the loss of the anterior portion. Although
these teeth are very deeply implanted in the maxillary bones, they
can hardly be said to possess a fang or root; for the form of the
part is the same throughout ; the covering of enamel is likewise
continued ; and that part, which at one period is contained in the
jaw, and would form the fang, is afterwards protruded to constitute
thr body of the tooth.

32 ON THE SKELETON OF MAMMALIA.

The constant growth of these teeth, therefore, proceeds in the same
manner, and is effected on the same principles as the original forma-
tion of any tooth, and can by no means furnish an argument for the
existence of vessels in the substance of the part.

We cannot help being struck with the great size of these teeth,
compared with the others of the saine animal, or even with the bulk
of the animal. Their length in the lower jaw nearly equals that of
the jaw itself, although a small proportion only of this length appears
through the gum. They represent the segment of a circle ; and are
contained in a canal of the bone, which descends under the sockets
of the grinders, and then mounts up, in some instances, to the root
of the eoronoid process : hence, although their anterior cutting edge
is in the front of the mouth, the posterior extremity is behind all the
grinding teeth. No animal exhibits this structure better than the
rat. The beaver also affords a good specimen of it on a larger
scale. It has been drawn in this animal by Blake, {Essay on the
Structure, Sfc. of the Teeth, tab. 9, fig. 3). The tooth does not extend
so far in the upper jaw ; it is there implanted in the intermaxillary
bone, and terminates over the first grinder.

The observations which have been made respecting the constant
growth of the incisor teeth of the gtires will apply also to the tusks of
the elephant. These are hollow internally, through the greater part
of their length, and the cavity contains a vascular pulp, which makes
constant additions of successive layers, as the tusk is worn down.
One of the elephants at Exeter Change is said to have nearly bled
to death from a fracture of the tusk, and consequent laceration of
the vessels of the pulp. The tusks of the hippopotamus, and pro-
bably all otlier teeth of this description, grow in the same manner.
Further and more accurate observation may hereafter shew, that the
same mode of growth obtains also in other classes of teeth when
they are exposed to great friction. Something similar may certainly
be observed in the grinders of the horse. The tooth is not finished
when it cuts the gum : the lower part of its body is completed while
the upper part is worn away by mastication, and the proper fang is
not added till long after. Hence we can never get one of these
teeth in a perfect state ; for if the part out of the gum is complete,
the rest of the body is imperfect, and there are no fangs : on the
contrary, when the fangs are formed, much of the body has been
worn away in mastication. Blake further asserts that this structure
is found in the grinders of the heaver, p. 99, tab. 9, fig. 4.

In the delphinus Gangeticus, of whicii there is a specimen in the
Hunterian collection, presented by bir J. Banks, the change that
takes place in the form of the tooth, as it wears away from long use,
is more remarkable than in most other teeth ; for the perfect tooth
has a tolerably sharp enamelled point, while the half-worn one has
a curved, blunted, cutting edge. See Sir Ev. Home's description of
the teeth of the delphinus Gangeticus, Phil. Trans. 1818, part 1,
p. 417.

ON THE SKELETON OF MAMMALIA. öö

§ 27. The corner teeth {canini) of the upper jaw lie close
to the intermaxillary bone ; hence the remarkable spiral tusk
of the narwliale^* and the tusks of the walrus belong to this
division. In many baboons, and most particularly in the larger
predacious mammalia, these teeth are of a terrific size : in the
latter animals, the whole profile of the anterior part of the
cranium forms a continuous line with these teeth, which is^
very visible in the tiger. The canine tusks of the babiroussa,
which are very long, and curved so as nearly to describe a
complete circle, present the most curious structure. Their
utility to the animal appears quite obscure, when their length,
direction, and smallness are considered. The small canine
teeth, which are situated just behind the larger ones, in all the
species of the deer and bear kind, are also remarkable. This
is the case in the brown bear of the Alps, of which I have
three crania ; in a black American ; in one whose country
is unknown, belonging to the national Museum at Paris ; and
in the Polar bear; of all which I possess excellent drawings,
through the kindness of Professor Cuvier. These small teeth
are wanting in the fossil remains of an ante-diluvian bear,
{ursus spelcsus) tov/ards the illustration of whose osteology I
have a large collection, from the four most celebrated caverns
in Germany, viz. that of Scharzfelder in the Harz, of Gailen-
reuter in the Fichtelberg, of Altensteiner in Thuringerwald,
and of Sunwicher in Iserlohn.

The narwhale is found so constantly with only one tusk, that it has
been called the sea-unicorn, and Linnaeus has even given it a similar
appellation, that of monodon. Yet there can be no doubt that it
possesses originally two of these ; one in either jaw-bone ; and that
which is wanting must have been lost by some accidental circum-
stance, as we can easily suppose, (Shaw's Zoology, vol. ii. p. 473).
These tusks often equal in length that of the animal's body ; which
may be eighteen feet or more ; yet they are always slender.

The result of Sir E. Home's examination of two specimens of the
male narwhale in the Hunterian collection, and of a female sent to
him by Mr. Scoresby, was, that the left tusk of this animal appears

• I must refer to tlie 5th part of my Delineations of Sulyects relating to Natvral
Hiftfry, for wliat is there said on the question, whetlier the iiurwhale has really one
or two of thes« teeth.

D

34 ON THE SKELETON OF MAMMALIA.

commonly long before the right one, and that the tusks in the tevriale
come much later than in the male, which facts explain the error of
Linnaeus, and that of the captains of the Greenland ships, who sup-
posed that the females had no tusks.

^ 28, The back teeth are the most universal ; since, when
mammalia have any teeth at all, they are of this description,
although the front and canine teeth may be wanting, as in the
armadillo and the ard-eater. The narwhale makes the only
exception, as it is perfectly toothless, if we except the long
tusk. The form, structure, and relative situation of the back
teeth vary very considerably. In many quadrumana and in
man the two front ones * are smaller in the crown, and more
simple in the fang than the posterior : whence J. Hunter calls
them bicuspides, and restricts the name of molares to the
latter.^

The molar teeth offeree and of man have the crown entirely
covered with enamel : this is the case also in the monstrous
fossile animal incognitum of the Ohio, (mammut Ohiotieum)
which has been called the carnivorous elephant.J In several
glires, (in some, as the marmot, the whole crown is covered
with enamel) in the solidungula, pecora,^ and most balcence,
bony substance may be seen at the extremity of the tooth,

* In some apes and baboons, the front bicuspis of the lower jaw has a peculiar for-
mation, being elevated into a sharp point, like those of the ferce. See the excellent
representation of the cranium of the mandril (simia maimon) in Cheselden's Osteo-
graphy,

t I find that the difference between the bicuspides and molares is noticed in
the first anatomical compendium, which was compiled from human bodies, viz, the
celebrated Anatomia partium Corp. Human., written by Mondini, in the first half of
the fourteenth century. For he enumerates in each jaw four maxillares, and six mo-
lares, besides the incisor and canine teeth, p. 370, of the classical edition, which is
accompanied with Berengar's Commentaries. I have also found, that this distinc-
tion of the two kinds of grinders is noticed in that famous volume of admirable
anatomical drawings, by the incomparable Leonardo da Vinci, which is preserved in
his majesty's library,

i See the 2nd part of Delineatio7is of Subjects relating to Natural History, tab, 19.

§ For the internal structure of the molar teeth of pecora, see Hollmann De Ossi-
bus Fossilibus, in the Commentar. Reg. Sac. Scient. Gotting. tom. ii. p. 263, and
Schteger, in Isenflamm's and Rosenmuller's Contributions towards Anatomy, vol. i,
part i. p. 5,

ON THE SKELETON OF MAMMALIA. 35

intermixed in a tortuous line with vertical productions of ena-
meL* In many animals which feed on grass, and do not
ruminate, as the solidungula and the elephant, the broad crowns
of the grinding teeth lie chiefly in a horizontal direction
towards each other. In most pecora, on the contrary, their
surface, which forms a zig-zag line, is oblique ; the outer mar-
gin of the upper teeth and the inner margin of the lower teeth
being the most prominent* In most predacious animals, par-
ticularly of the lion and dog kind, the crownS of the molar
teeth are compressed, and terminate in pointed processes, the
lower ones shutting within the upper ; so that in biting they
intersect each other, like the blades of a pair of scissars, in
consequence of the firm hinge-like articulation of the cylin-
drical condyle.

The distribution of the enamel and bony svxhstance varies in the
teeth of different animals, and even in the different orders of teeth
in the same animal.

All the teeth of the Carnivora, and the incisors of the ruminating
animals, have the crown only covered with enamel, as in the human
subject. The immense fossil grinders of the animal incognitum, or
mammoth, have a similar distribution of this substance.

The grinders of graminivorous quadrupeds, and the incisors also
of the horse, have processes of enamel descending into the substance
of the tooth. These organs have also in the last^-mentioned animals
a third component part, differing in appearance from both the others,
but resembling the bone more than the enamel. Blake has distin-
guished this by the name of crusta petrosn ; and Cuvier calls it cement.

The physiological explanation of this difference in structure is a
very easy and clear one. The food of the Carnivora requii'es very
little comminution before it enters the stomach : hence, the form of
their molar teeth is by no means calculated for grinding ; and, as the
articulation of the jaw admits no lateral motion, these teeth, of
which the lower are overlapped by the upper, can only act like the
incisors of other animals. The food of graminivorous quadrupeds is
subject to a long process of mastication, before it is exposed to the
action of the stomach. The teeth of the animals suffer great attri-
tion during this time, and would be worn down very rapidly but for
the enamel which is intermixed with their substance. As this part
is harder dian the other constituents of the teeth, it resists the attri-
tion longer, and presents the appearance of prominent ridges on the

• 'J'he specifically different forms of the layers of enamel, in the African and
Aiialic elfphant$, may be »eeji in the Delineation», &c. part ii. tab. 19.

D 2

36 ON THE SKELETON OF MAMMALIA.

worn surface, by which the grinding of the food is much facilitatecf.
The distinction of the three substances is seen better in the tooth
of the elephant than in any animal. The best method of displaying
it is by making a longitudinal vertical section, and polishing the cut
surface. The crusta petrosa will then be distinguished by a greater
yellowness and opacity in its colour ; and by an uniformity in its ap-
pearance, as no laminae or fibres can be distinguished.

The pulp of a grinding tooth of a graminivorous quadruped is di-
vided into certain conical processes, which are united at their bases.
These vary from two to six in the horse and cow. On these the
bone of the tooth is formed, as on the single pulp of the human sub-
ject, but it is here divided into as many separate shells as there are
processes of the pulp ; all of them, however, enclosed in a common
capsule. The ossification commences, as in all teeth, on the points
of the pulp, and extends towards the basis : when it has arrived
there, the shells unite together ; and they also join at their outer
margins. Between the processes of the pulp other productions de-
scend from the capsule in a contrary direction ; and deposit, on the
surface of the shells», enamel distinguishable by its crystalline ap-
pearance, and hence denominated by Blake cortex striatus. When
these membranous productions have formed their portions of enamel,
they secrete the crusta petrosa within the cavities left between them.
The outer surface of the bone of the tooth is covered by enamel,
which may be compared to that which invests the crown of a human
tooth, except that it is deposited in an irregular waving line, in order
to render the surface better calculated for grinding ; and the inequa-
lities of this surface of enamel are filled up by crusta petrosa. The
exterior enamel, and crusta petrosa, (which may be so named, by
way of distinguishing them from the processes within the tooth) are
formed by the surface of the capsule.

If, then, we make a transverse section of a grinding tooth of the
horse or coxv, the exterior surface will be found to consist of an irre-
gular layer of crusta petrosa : this is succeeded by a waving line of
enamel, within which is the proper bone of the tooth. But the sub-
stance of the latter is penetrated by two productions of enamel ; in
the interior of each of which is crusta petrosa.

The crusta petrosa, which fills these internal productions of
enamel, is sometimes not completely deposited before the tooth cuts
the gum : hence, cavities are left in the centre of the tooth, which
become filled with a dark substance composed of the animal's food,
and other foreign matters. This seldom happens to any considerable
extent in the grinders of the horse. In the cow and sheep these cavi-
ties are constantly filled with the dark adventitious matter; the
crusta petrosa being confined to the exterior surface of the tooth,
and not existing even there so plentifully as in the horse.

The lower grinders of the horse differ very much in their forma-
tion from those of the upper-jaw. Ossification commences in these
by four or five points, which increase into as many small shells ; yet
they unite without any processes of the capsule passing down between

ON THE SKELETON OF MAMMALIA. 37

to form internal productions of the enamel. This substance is l)OW-
ever deposited in a very convoluted manner on the bone of the
tooth, so that the same end is attained, as if productions of the
cortex striatus had existed in the centre of the part. The crusta pe-
trosa fills up the irregularities of this waving line of enamel. A ho-
rizontal section of such a tooth presents the three substances ar-
ranged within each other : the crusta petrosa is external ; then comes
the enamel, which includes nothing but the proper bone of the tooth.

The incisors of the horse have a production of enamel in their
centre ; but the cavity which this forms containing no crusta petrosa,
is merely filled by the particles of food, &c. As these processes
of enamel descend only to a certain extent in the tooth, they disap-
pear at last from the constant wear of the part in mastication ; and
this is improperly called the filling up of the teeth. Hence a crite-
rion arises of the horse's age.

The grinding teeth of the elephant contain the most complete in-
termixture of the three substances, and have a greater proportion of
crusta petrosa than those of any other animal. The pulp forms a
number of broad flat processes, lying parallel to each other, and
placed transversely between the inner and outer laminae of the
alveoli. The bone of the tooth is formed on these in separate shells
commencing at their loose extremities, and extending towards the
basis where they are connected together. The capsule sends an
equal number of membranous productions, which first cover the
bony shells with enamel, and then invest them with crusta petrosa ;
which latter substance unites and consolidates the different portions.
The bony shells vary in number from four to twenty-three, accord-
ing to the size of the tooth, and the age of the animal : they have
been described under the term of denticuli, and have been repre-
sented as separate teeth in the first instance. It must, however, be
remembered, that they are formed on processes of one single pulp.

When the crusta petrosa is completely deposited, the different den-
ticuli are consolidated together. The l)ony shells are united at their
base to the neighbouring ones ; the investments of enamel are joined
in like manner ; and the intervals are filled with the tliird substance,
which really deserves the name bestowed on it by Cuvier, of cement.
The pulp is then elongated for the purpose of forming the roots or
fangs of the tooth. From the peculiar mode of dentition of the ele-
phant, the front portion of the tooth has cut the gum, and is em-
ployed in mastication, before the back part is completely formed,
even before some of the posterior denticuli have been consolidated.
The back of the tooth does not appear in the mouth until the ante-
rior part has been worn down even to the fang.

A horizontal section of tlie elephant's tooth presents a series of
narrow bands of bone of the tooth, surrounded by corresponding
portions of enamel. Between these are portions of crusta petrosa ;
and the whole circumference of the section is composed of a thick
layer of the same substance.

A vertical section in the longitudinal direction exhibits the pro-

38 ON THE SKELETON OF MAMMALIA.

cesses of bone, upon the different denticuH, running up from the
fangs ; a vertical layer of enamel is placed before, and another be-
hind each of these. If the tooth is not yet worn by mastication the
two layers of enamel are continuous at the part where the bone ter--
minates in a point ; and the front layer of one denticulus is continu-
ous with the back layer of the succeeding one, at the root of the
tooth ; so that the enamel, ascending on the anterior, and descend-
ing on the posterior surface of each denticulus, forms a continued
line through the whole tooth. Critsia petrosa intervenes between
the ascending and descending portions of the enamel.

As the surface of the tooth is worn down in mastication, the pro-»
cesses of enamel, which are capable of making a resistance by their
superior hardness, form prominent ridges on the grinding surface,
which must adapt it excellently for bruising and comminuting any
hard substance.

The grinding bases, when worn sufficiently to expose the enamel,
present a very different appearance in the Asiatic and African ele-
phants. The processes of enamel in the former species represent
flattened ovals, placed across the tooth. In the latter they form a
series of lozenges, which touch each other in the middle of the
tooth.

It does not appear that crusta petrosa is an essential part in the
grinders of graminivorous animals. For those of the rhinoceros do
not possess it, although the enamel descends into their substance, and
forms a cavity, which is filled with the food, &c.

Home and Blake likewise state, that it does not exist in the hippo-!-
potannis, where there are internal productions of enamel : but Mr.
Macartney has found it in small quantity on the exterior surface of
the tooth near its root.*

§ 29. Certain classes of the teeth are entirely wanting in
some orders, classes, and genera of quadrupeds ; as the upper
front teeth in the pecora, the lower in the elephant, both in
the African rhinoceros, and the canine in the glires. In other
instances, the different descriptions of teeth, particularly the

* Mr. Corse's Observations on the different Species of Asiatic Elephants. Philos.
Trans. 1799, part ii.

Some Observations on the Teeth of graminivorous Quadrupeds, by E. Home, Esq.
Ibid. With Delineations of the Teeth of the Elephant, Horse, Cow, Sheep, Hippopota-
mus, and Rhinoceros,

Blake's Essay on the Structure and Formation of the Teeth in Man and various Ani-
mals, wit'a plates.

Tenon Sur une Methode particuliere d'etudier l' Anatomie, in the M6moires de Vln-
stitut National, torn. i. an 6.

Cuvier, L6gom d' Anatomie comparie, torn. iii.

ON THE SKELETON OF MAMMALIA.

ssi

canine and molar, are separated by considerable intervals ;
this happens in the horse and bear. There is no animal in
which these parts are of such equal height and such uniform
arrangement as in man.

All the three kinds of teeth are found in the quadnimana, the
Carnivora, the pachydermata, (excepting the izvo-horned rhinoceros and
elephant) the horse, and those ruminating animals which have no
horns.

Cuvier states, that the teeth of an animal whose bones are found
in a fossile state resemble those of man, in being arranged in a con-
tinued and unbroken series.

In the sitnicB, Carnivora, and all such as liave canine longer than
the other teeth, there is at least one vacancy in each jaw, for lodging
the cuspidutus of the opposite jaw. There is a vacancy behind each
canine in the bear.

The horned ruminating animals not only want entirely the upper
incisors, but they are also destitute of cuspidati, except the stag,
which has rudiments of these teeth ; and the 7nusk, (nioschus mosohifer')
in which they are very long, and curved in the upper jaw.

Between the incisors and grinders of the horse a very large vacancy
is left, in the middle of which a small canine tooth, termed the tush^
is found in the male animal, but very rarely in the female.

The elephant has grinders and two tusks in the upper jaw, but the
former only in the lower. The immense tusks belong properly to
the male animal ; as they are so small in the female, generally speak-
ing, as not to pass the margin of the lip. (Corse, in Phil. Trans.
1799, part 2, p. 208.)

The sloths have grinding and canine teeth, without incisors. The
dolphin and porpoise have small conical teeth, all of one size and
shape, arranged in a continued line throughout the alveolar margin
of both jaws. The cachalot [physeter macrocephalus) has these in the
lower jaw only. The teeth of the seal are all of one form, viz. that
of the canine kind, conical and pointed.

The narivhale has no other teeth than the two long tusks implanted
in its OS intermaxillare, of which one is so frequently wanting. A
head, in which there are two of these tusks, is delineated by Dr.
Shaw, in his Zoology, from a specimen in the Leverian Museum.
These tusks are remarkable for the spirally convoluted appearance
of their external surface. They are hollow internally, and probably
have a constant growth like the elephant's tusks. See § 27.

^ 30. The want of satisfactory observations* prevents us
from saying much on the change of the teeth, particularly in

* See the detailed description of the change of the teeth in tiie horse by Tenon,
Stir une Methode particulicre d'eludier L' Anatomie, in the M^in. de Clnstilut National,
torn. ii. p. 558 ; and J. W. Neergaard's Naturbeschreibung der Zahne den Pferdes mit
Rücksicht auf andre Thi^e, Kopenh. 1816.

40 ON THE SKELETON OF MAMMALIA.

wild animals. Among the digitata many of the glires, as
the marmot and rabbit, do not appear to change their teeth.*
Some erroneous opinions of former times, as, for instance, that
the domesticated pig changes its teeth, and that the wild ani-
mal does not, hardly require an express contradiction in the
present day.*!* During the time of change in the ferts, parti-
cularly in the dog and otter, the number of their canine teeth
often seems doubled, since the permanent ones cut the gum
before the deciduous have fallen out. Apes, like the human
subject, have no bicuspides among the deciduous teeth ; but
there are, instead of these, two proper molares on either side
of the jaw. J The change of the teeth takes place in the
elephant in a very remarkable manner.§ The new permanent
tooth comes out behind the milk tooth, the vertical layers of
which are gradually removed,|l as the formation of the latter
advances.? There is, however, perhaps no animal of this
class, in which the first appearance and subsequent removal
of the deciduous teeth takes place at so late a period of life as
in man.

The permanent teeth are generally formed in cavities near the
roots of the temporary ones, and they succeed to the vacancies left
by the discharge of the latter.

A different mode of succession obtains, however, in some instances.
The adult molares of the human subject are not formed near any of
the temporary teeth, but in the back of the two jaws ; from which
situation they advance successively towards the front, in proportion
as the maxillary bones are lengthened in that direction. A similar,
but much more remarkable species of succession is observed in the
grinders of the elephant, where it was ascertained by the labours of
Mr. Corse, who has explained and illustrated the subject in a series

* Le Galloi's Experiences sur le Principe de la Vie.
t See Home, Phil. Trans. 1801.

I In the skull of a young orang-outang of Borneo, which I possess through the
kindness of Mr. Van Marum, there are no bicuspides.

$ The progression of dentition in the molar teeth of the elephant has been most
accurately described by Cuvier, in vol. i. Recherches svr les Ossemens Fossiles, p. 38.

II See Prof. Brugman's remarks on this subject, in Van Maanen Diss, de Absorp-
tione Solldorum. Lugd. Bat. 1794.

^ I have given a drawing in the Petersburgh Prise Dissertation on Nutrition, 1789,
4to. of the peculiar formation of these vertical layers in the molar teeth of the ele-
phant, before they appear through the gum ; and particularly of the manner ip
which the enamel exudes from the bony substance in small processes.

ON THE SKELETON OF MAMMALIA. 41

of beautiful engravings. See Observations on the different Species of
Asiatic Elephants, and their Mode of Dentition. Phil. Trans. 1799,
part 2.

We never see more than one grinder and part of another through
the gum in this animal. The anterior one is gradually worn away
by mastication ; its fangs and alveolus are then absorbed : the pos-
terior tooth coming forwards to supply its place. As this goes
through the same stages as the preceding grinder, a third tooth,
which was contained in the back of the jaw, appears through the
gum, and advances in proportion as the destruction and absorption
of the other proceed. The same process is repeated at least eight
times, and each new grinder is larger than that which came before it.
The 1st, or milk grinder, is composed of four transverse plates or
denticuli, and cuts the gum soon after birth. The 2d, which has
eight or nine plates, has completely appeared at the age of two
years. The 3d, formed of twelve or thirteen, at six years. From
the 4th to the 8th grinder, the number of plates varies from fifteen
to twenty-three, which is the largest hitherto ascertained. The
exact age at which each of these is completed has not yet been
made out : but it appears that every new one takes at least a year
more for its formation than its predecessor.

From the gradual manner in which the tooth advances, it is mani-
fest that a small portion of it only can penetrate the gum at once.
A grinder, consisting of twelve or fourteen plates, has two or three
of these througli the gum, whilst the others are embedded in the jaw.
The formation of the tooth is complete therefore, first, at its anterior
part, which is employed in mastication, while the back part is very
incomplete ; as the succeeding laminae advance through the gum,
their formation is successively perfected. But the posterior layers
of the tooth are not employed in mastication, until the anterior ones
have been worn down to the very fang, which begins to be absorbed.
One of these grinders can never therefore be procured in a perfect
state ; for if its anterior part has not been at all worn, the back is not
completely formed, and the fangs in particular are wanting, while
the structure of the back of the tooth is not completed until the
anterior portion has disappeared.

A similar kind of succession, but to a less extent, has been ascer-
tained by Sir Everard Home, in the teeth of the sus Mthiopicus.

Observations on the Structure of the Teeth of Graminivorous Quadru-
peds; particularly those of the Elephant and sus Äthiopiens, Phil.
Trans. 1799, part 2.

The researches of the same gentleman have also proved it to exist
in the wild boar to a certain degree, and have rendered it probable
that it occurred likewise in the animal incogniiuin {mammoth).

Observations on the Structure and Mode of Groivth of the Wild Boar
and Animal Incogniturn. Phil. Trans. 1801, part 2.

§ 31. The crown of the tooth is gradually worn clown b)
the act of mastication, and receives from this cause a kind of

42 ON THE SKELETON OF MAMMALIA.

polished surface, which is especially observable in the canine
teeth of the pig and hippopotamus. The age of the horse is
determined by the appearance of the front teeth. It has been
observed in the glires, that when the upper or lower pair of
incisors is lost, the opposite teeth grow out to a monstrous
length. A similar growth takes place when these animals are
confined to soft food.*

§ 32. From the head of mammalia we proceed to consider
the trunk, according to its division into the three principal
parts of spine, pelvis, and chest. The former of these is the
most constant part of the skeleton, as it belongs to all red-
blooded animals without exception, and is not found in a single
white-blooded one.

§ 33. It is remarkable, that the animals of this class, at
least the four-footed ones, constantly agree in the number of
their cervical vertebrae. The giraffe or the horse have nei-
ther more nor fewer than the mole or ant-eater. In all there
are always seven, as in the human subject. An unexpected
irregularity has been discovered by Cuvier in the three-toed
sloth ,•']- it has nine vertebree of the neck. In some cetacea, on
the contrary, there are only six ; and, in these animals, four or
five are generally consolidated together. The atlas is distin-
guished in the ferce by its immense strength, and by the vast
size of its transverse processes.:|:

The number of cervical vertebrse is the same in the cetacea as in
other mammalia, according to Cuvier, but some of them are anchylosed.
Thus the two first are united in the dolphin and porpoise; and the six
last in the genus physeter. Legons d'Anat. comp. torn. i. p. 154.

It must be accounted a singular circumstance, that the number of
cervical vertebrse should be so constantly the same in animals, whose
neck differs so much in length, when the number of pieces in the
other regions of the spine varies greatly in the different genera. No
instance has been recorded, in which more than seven cervical ver-
tebrae have been found in the human subject, although the number

* See Morton's Natural History of Northamptonshire, p. 445 ; and Achard's
Chymico-Physical Writings, p. 161.

t Annales du Museum d'Histoire Naturelle, vol. v. p. 202.

t The connexion which this structure has with the teeth and jaws of these rapa-
cious animals is pointed out by Eustachius De Dentibus, p. 86 ; see also Vesling
in Severini Vipera Pythia, Patav, 1651, p. 232.

ON THE SKELETON OF MAMMALIA. 43

of those in the back and loins sometimes deviates from the natural
standard.

The transverse processes of the vertebrae, which are particularly
conspicuous in such carnivorous animals as have great strength in
their neck, afford attachment to the large and powerful muscles by
which the animal executes those strong and rapid motions of the
head, which are necessary in attacking its prey, or defending itself.
The badger, in this country, affords an excellent specimen of the
structure alluded to.

The mole and shrew have no spinous processes in the neck. The
vertebrie form simple rings, with considerable motion on each other.
These processes are either very short, or altogether deficient in the
long-necked animals, as the horse, camel, giraffe, &c. They woiüd
otherwise afford an obstacle to the bending of the neck backwards.

The six last vertebrae of the neck are anchylosed in the ant-eater
and manis.

S 34. The number of dorsal vertebrae is determined by that
of the ribs, which will be spoken of presently. In the long-
necked quadrupeds, as the horse, giraffe, camel, and other
pecora, as well as in those animals whose head is very heavy,
as the elephant, the spinous processes of the anterior dorsal
vertebrae are exceedingly long, for the attachment of the great
suspensory ligament of the neck (ligamentum nuchae).

§ ^b. The lumbar vertebrae vary much in number. The
elephant has only three ; the camel seven. Some quadrumana,
as the mandrill, have the latter number. The horse has six ;
the ass five. Mules have generally six, but sometimes only
five. Most quadrupeds have the processes of these vertebrae
turned forwards ; in the ape, they are in their ordinary posi-
tion, turned upwards.* The transverse processes are remark-
ably large in many ruminantia, as also in the hare.

§ 2ß. The form and proportions of the sacrum are still
more various. The number of its vertebrae, as they are called,
varies in the different species of the same genus. Thus, in
the common bat it consists of four pieces ; in mostt of the

* Galen, in his Osteology, describes the transverse processes as having this di-
rection ; from which circumstance, as well as from his description of the sacrum and
01 coccygis, and several other passages, Vesalius shewed that the work was drawn up
from the examination of apes, not of the human subject. See his Epistola nttionein
modwnque propinandi Radicis Chyiiai decucti pertractans, 1546, p. 49.

t Vesalius De Corp, Jlvm, Fahrica, p. 99.

44 ON THE SKELETON OF MAMMALIA.

sitnice it consists of three pieces ; in the orang-outang of four ;*
in the chhnpanse\ of five. This bone is distinguished in the
horse by large lateral processes at its anterior extremity ; and
in the mole by a thin sharp-edged plate, formed by the union
of its spinous processes.:]: A somewhat similar structure is
found in the armadillo, in which animal the whole pelvis has
a very anomalous formation. As the cetacea have no pelvis,
they cannot be said to possess a sacrum.

Most of the simice, and even some which very rauch resemble the
human subject, as the orang-outang, which Camper dissected, (simia
pygmoEus) have the sacrum formed of three pieces, which consequently
leave only two pairs of openings for tlie passage of the nerves. Now,
as Galen mentions these circumstances of the human sacrum in his
work on the bones, it must appear very clearly that the description
could not have been taken from the human subject, but was probably
derived, as Vesalius supposed, from the ape; although Silvius and
Eustachius have endeavoured to invalidate this conclusion. See
Vesal. Epist. de Rad. Chynce ; also his great work. De Corp. Hum.
Fabrica, p. 99.

The true orang-outang (simia satyrus) has a sacrum composed of
five pieces. The elephant has also five. See Blair, Osteogr. Ele-
phanfina, p. 29.

§ 37. The OS coccygis is prolonged, so as to form the tail
of quadrupeds ; and consists, therefore, in many cases, of a
great number of vertebrse. In the cercopilhecus morta there
are 22 ; in the cercopilhecus paniscus, 32 ; in the two-toed
ant-eater, 41. When an opossum or monkey loses a portion
of the tail, (an accident which has often led to confusion in
determining the species) a peculiar knotty excrescence, some-
times of a carious appearance, takes place at the truncated
extremity.

In monkeys, and even in such simice as have no tails, where the os
coccygis consists at most of three pieces only, this bone is perforated
by a continuation of the vertebral canal, and by openings for the
transmission of nerves. This structure is ascribed by Galen to the

* Camper states, that the sacrum of this animal has three pieces : in my speci-
men, however, there are manifestly four.

t Tyson's Anatomy of a Pigmy, edition of 1751, p. 89.

X Its skeleton, which is altogether very curious, is accurately described by
Wiedemann, in his Archives of Zoology and Zootomy, vol. i. p. 106. There is also a
delineation of the skeleton of an armadillo, prefixed to the 8th chapter of Chesel-
den's Osteography.

ON THE SKELETON OP MAMMALIA. ^fS

human coccyx ; and hence Vesalius has derived another argument,
to shew that Galen's Osteology was not drawn from the human
skeleton.

The orang-outang, like man, has a coccyx composed of five pieces,
not perforated. Tyson's Anot. of a Pigmy, p. 69.

Those vertebrae of the tail of mammalia, which are nearest to the
sacrum, are perforated by a continuation of the canal for the medulla
spinalis. The lower ones are solid. The want of a pelvis renders it
impossible for us to decide the number of sacral and coccygeal verte-
brae in the cetacea ; but the whole number of pieces in the spine of
the dolphin and porpoise is 66.

§ 38. The ossa innominata, together with the sacrum, con-
stitute the pelvis.* There is ground for affirming, although
the assertion may appear paradoxical, that no animal but man
has a pelvis ; for in no instance have the bones of this part that
bason-hke appearance, when united, which belongs to the hu-
man subject. Those apes, which most nearly resemble man,
have the ossa innominata much elongated ; and in the ele-
phant, horse, &c. the length of the symphysis pubis detracts
from the resemblance to a bason. In some instances, as in the
beaver and kangaroo, the ossa pubis are not united by syn-
chondrosis, but consolidated into one piece by a bony union.
They are, on the contrary, separate in the ant-eaters, in the
same manner as they are found in birds. The cavity of the
pelvis is so narrow in the mole, that it cannot hold the organs
of generation and neighbouring viscera, which lie therefore
externally to the ossa pubis. In the kangaroo,-^ and other mar-
supialt a7iimals, the superior, or rather the anterior margin
of the ossa pubis, is furnished with a peculiar pair of small
bones (ossa marsupialia, or cornua pelvis abdominalia) some-
what diverging from each other, and running towards the ab-
domen. They have an elongated and flattened form, and be-

• B. G. Schreger, Pelvis Anim. Brutorum cum Humana Comparatio. Lips. 1787,
4to. Autenrieth and Fischer Observatinnes de Pelui Mammalium. Tubing. 1798, 9.
Plates of the pelvis of the cow, accurately measured in G. Eberhard Over hel
Verlassen de-r Koe.ijen. Amst. 1798.

t E. Home On the Mode of Generation of the Kangaroo. Philos. Transact. 1795.

t Daubenton, vol. x. tab. 51. I refer here, and in other places, where a similar
quotation occurs, to the original 4to. edition of BufFon's work. It cannot, with pro-
priety, be quoted under the name of Buffon, since it is well known that the zooto •
mical part wa.1 furnished by Daubenton, and has been omitted in most of the subse-
quent edition«.

46 ON THE SKELETON OF MAMMALIA»

long exclusively to these animals. But in the Philos. TranS*
of 1802, it is stated by sir E. Home, that the ornithorhynchttS
has something of this kind. They support the abdominal
pouch in the female, but are also found in the male ; at least
in some species. Cetaceous animals have no hind feet, nor ossa
innominata, consequently no pelvis ; they have, however, a pair
of small bones at the lower part of the belly, which may be
compared to the ossa pubis.*

§ 39. The thorax in most, if not all animals, the marmot
perhaps excepted, of the class mammalia, is narrower, and
deeper from the spine to the sternum, than in man. The less
marked flexure of the ribs of animals, and the elongation of
their sternum give rise to this peculiarity. The long legged
animals, as the giraffe, and those of the stag kind, possess this
keel-like form of the chest {thorax carinatus) in the most strik-
ing degree.

I 40. In a very few mammalia, as some bats and armadil-
las, there is a pair of ribs less than in man ; but in the greater
number of this class there are more. Several quadrumanct
have 14 pairs; the horse, 18; the ornithorhynchus, 17; the ele-
^hant, 20;*^ the two-toed sloth, {bradypus didactylus) 23. The
two-toed ant-eater {myrmecophaga didactyla) has 16 pairs>
which are remarkably broad, so that the back and sides of the
skeleton, as low as the ossa innominata, appear like a coat of
mail.

The ornithorhynchus paradoxus and Mstrix have ribs of a very sin-
gular structure. Their true ribs, which are six in number, consist of
two pieces of bone ; a longer one joined to the spine, and a shorter
connected to the sternum. These are united by means of a piece of
cartilage ; so as to constitute a structure approaching to that of birds.
The false ribs, ten in number, terminate anteriorly in broad, flattened,
oval bony plates, connected together by elastic ligaments. Phil. Trans.
1602, part 1, plate 3. Meckel de ornithorhyncho paradoxe, 1826.

§ 41. The sternum in most of the mammalia is cylindrical,

* Rondelet De Piscibus, p. 461. Tyson's Anatmiy qfa Porpoise. London, 1680,
p. 28.

t There axe only nineteen in the skeleton of the Asiatic elephant at Cassel. Blair
found the same number in the individuals of which he has given so excellent an ac-
count ; and a manuscript Italian description of the elephant, which died at Florence
in 1657, confirms this statement.

ON THE SKELETON OF MAMMALIA. 47

and jointed. This structure occurs even in the quadrumana
and the bears, whose skeletons, in other respects, resemble the
human. The form of this hone is the most singular in the
mole ;* where its anterior extremity is prolonged into a pro-
cess, almost resembling a ploughshare, lying under the cervi-
cal vertebrae, and parallel with them.

This process may be compared to the keel-like projection of the
sternmTd of birds. "It serves for the origin of those strong muscles of
the anterior extremity, which assist the animal in digging its way un-
der ground.

§ 42. We proceed to speak of the extremities, as they are
called, which, although they vary considerably in the class of
mammalia, may, on the whole, be compared to those of man in
their chief component parts, and in the mode in which these
are connected together.

Some passages of Aristotlef have givein rise to the singular
mistake of supposing that the elbow and knee of quadrupeds
are bent in a direction exactly opposite to that of the human
subject. The error must have arisen from the shortness of
the thigh and arm bones, which lie close to the trunk, particu-
larly in long-legged quadrupeds, and do not project freely as
in man, the quadrumana, the bear, the elephant, &c. Hence
the different bones of the extremities in these animals have
been compared to such parts in the human body as do not in
reality correspond with them.:}:

We may assert, as a general observation, that the four component
parts of the upper extremity, viz. the shoulder, arm, fore-arm, and
hand, can be clearly shown to exist in the anterior extremities of all
mammalia ; however dissimilar they may appear to each other on a
superficial inspection, and however widely they may seem to deviate
from the human structure.

* It is hardly necessary to remind the readers, that the terms anterior, posterior,
superior, and inferior, are always applied to quadrupeds with reference to the hori-
zontal position of their body. Consequently the term anterior designates those parts,
which, in the erect position of the human body, are superior ; and so of the others,

t Aristot. Hist. Anim, 2. 1 ; and De hicessii Anitn. c. 11, Plin. ii. 102.

X See on this subject Fab. ab Aquapend. De motu lucaü Animaiium securidum
totum, in his Oper. Anat, p. 343, Albinus's ed. ; and Barthez Des Mouvemens Pro-
gressifs de I'Homme, in the Journal det S^avans, January, 1783, p. 34, of the Paris
4to. edit.

48 ON THE SKELETON OF MAMMALIA.

Whenever an animal of one class resembles those of a different
order in the form and use of any part, we iTiay be assured that this
resemblance is only in externals ; and that it does not affect the num-
ber and arrangement of the bones. Thus the bat has a kind of wings,
but an attentive examination will prove, that these are really hands,
with the phalanges of the fingers elongated. The dolphin, porpoise^
and other cetacea, seem to possess fins, consisting of a single piece.
But we find, under the integuments of the fin-like members, all the
bones of an anterior extremity, flattened in their form, and hardly
susceptible of any motion on each other. We can recognize very
clearly the scapula, humerus, bones of the fore-arm, and a hand con-
sisting of five fingers ; the same parts, in short, which form the ante-
rior extremity of other mammalia. See Tyson's Anatoiny of a Por-
poise, fig. 10 and 11 : also Blasii Anafumia Animalitim, tab. 51, fig.
3,4.

The fore-feet of the sea-otter, seal, walrus, and manati, form the con-
necting link between the anterior extremities of other mammalia,
and the pectoral fins of the whale kind. The bones are so covered
and connected by integuments, as to constitute a part, adapted for the
purposes of swimming ; but they are much more developed than in
the latter animals, and have free motion on each other.

The cold-blooded quadrupeds bear great analogy in the four com-
ponent parts, and in the general structure of their anterior extremi-
ties, to the warm-blooded ones. See Caldesi's Observations on the
Turtle, tab. 3, fig. 1, 4, 5.

The bones of the wing of birds have a considerable and Ainexpect-
ed resemblance to those of the fore-feet of the mammalia ; and the
fin-like anterior member of the penguin contains, within the integu-
ments, the same bones as the wings of other birds.

^ 43. The clavicle has been said, even by some excellent
modern zoologists, to be confined to Linnaeus's order primates
(in which he includes man, the quadrumanous animals, and
bats) ; but it exists in a great number of mammalia* besides
these ; particularly in such quadrupeds as make much use of
their fore-feet, either for holding objects, as the squirrel and
beaver ; or for digging, as the mole ; or for raking the ground,
as the ant-eater and hedgehog ,•+ or for climbing, as the sloth.
Many other animals have, in its place, an analogous small bone,

* J. G. Haase, Comparatio clavic. Anim. Brut, cum Humanis, Lips. 1 766, 4to,
Vicq d'Azyr Sur les Clavicules and Les Os Clavic. in Mem. de I'Acad. des Sciences,
1785.

t The use of the clavicles in some of the animals here enumerated is well pointed
out by Fab. Hildanus, in his Short Description of the Excellence of Anatomy, Benw
J 624-8, p. 219.

ON THE SKELETON OF MAMMALIA. 49

merely connected to the muscles,* and called by Vicq d' Azyr
OS claviculare to distinguish it from the more perfect clavicles.
This is the case with most of the fer(E,\ and some glires.
Lastly, the form and relative magnitude of the true articulated
clavicles are subject to great variety. They are excessively
long in the bat. Those of the orcmg-otitang have the great-
est resemblance to the human subject. In the two-toed ant-
eater their form is that of a rib : their figure is most anomalous
in the mole,% where they are nearly cubical. They are entirely
wanting in the long-legged quadrupeds with keel-shaped chest;
viz. the pecora and solidungula ; as well as in the cetacea.

The clavicle supports the anterior extremity, and maintains the
shoulder at its proper distance from the front of the trunk. It exists,
therefore, in all such animals as make much use of these members, whe«
ther for the purpose of climbing, digging, swimming, or flying. It
does not exist, on the contrary, in such as use their fore-feet merely for
the purpose of progression ; since these limbs must be brought more
forward on the chest, that they may support that part, by being
placed perpendicularly under it. In the genera, which hold an inter-
mediate rank between these, which do not possess so much power in
the fore-feet as the first division of animals, and are not so limited in
their employment as the second, the clavicular bones, or imperfect cla-
vicles, exist.

§ 44. The scapula exists in all red-blooded animals, which
have anterior extremities, or similar organs of motion : conse*
quently in both classes of warm-blooded animals without ex-
ception. The form of this bone varies much even in mamma-
lia ; and particularly the relation which its three sides bear to
each other. This depends on the position of the bone, which
is determined by the general form of the chest. The margin,
which is turned towards the spine, is the shortest in most of
the proper quadrupeds, particularly the long-legged ones with
narrow chest ; in which the scapulae lie on the sides of the
chest. In some, as the elephant, the chiroptera, most of the

• Hence, Serae compares it to the sesamoid bones. See his Opusc de Phijüca
Argumento. Naples, 1766, 4to. p. 84.

t Pallas Spicilegia Zoolo/rica, fascic. 14, p. 41.

} On this point, and the whole subject of the osteology of the mole, see Jacob's
Annlome taljia: Eurnpca. .Ten, 1816. -

E

50 ON THE SKELETON OF MAMMALIA.'

quadrumana, and especially in man, this margin is the longest,'
The scapula of the mole* has a completely anomalous figure^
almost resembling a cylindrical bone. The coracoid process
and acromion, the two chief projections of this bone, are strong-
est in such animals as have two long clavicles ; which might
have been inferred ä priori.

V 45. The remarkable varieties of the anterior extremities,
properly so called, may be most conveniently considered accord-
ing to the orders and genera of animals of this class. The bat
and the mole present the widest deviations from the ordinary
formation of these parts. The radius is deficient in the fore-
arm of the former; or at most there is only a slender sharp-
pointed rudimentt of this bone ; their thumb is short, and fur^
nished with a hook-like nail : the phalanges of the four fingers,
between which the membrane of the wing is expanded, are on
the contrary extremely long and thin, almost like the spines of
a fish, and have no nails.^ The flying squirrel has a peculiar
sharp-pointed bone at the outer edge of its carpus, connected
to that part by means of two small round bones, which ena-
bles it to spring from great heights. The form of the os hu-
meri in the mole is altogether unparalleled ; it is thin in the
middle, and surprisingly expanded at either extremity. The
shovel-like paw of this animal is provided with a peculiary*«/-»
ciform bone, lying at the end of the radius. The phalanges of
the fingers are furnished with numerous processes, and have
moreover sesamoid bones ; all which, by increasing the angle
of insertion of the tendons, contributes to facihtate muscidar
motion. The animals with divided claws and hoofs have some
peculiarities in the metacarpus and metatarsus. In the pig.

* On the wonderful structure of the scapula, and its connexion with the anoma-»-
lous clavicle and sternum of the ornithorhynchus, see Home, Phil. Trans. De Blainville,
Diss, sur la Place que la Familie des Ornithorynques et des Echidnas doit occuper dans
les Siries Naturelles. Paris, 1812 ; and JafF6 De Ornithorhyncho Paradoxa. Berol.'
1823.

t Weygand, Suppl. IV. to the Breslau Collection, p. 55.

X Lion. Da Vinci endeavours to prove from the structure and mechanism of the bat,
and not of birds, in what manner men might also be able to fly. y'lA. Amoretti
Vita a L. D. V. p. 145.

ON THE SKELETON OF MAMMALIA. 51

these parts consist of four cylindrical bones. In the seal the
large bones of the anterior extremities are not cylindrical, but
flattened ; by which structure they serve better the purpose
of rudders. In the ^ecora, before birth, there are two lying
close together ; but they are afterwards formed into one by
the absorption of the septum.* The horse has a single bone
{gamba, Vegetius ; in French, le canon ; in English, the can-
non bone, or shank bone), with a pair of much shorter and im-
moveable ones, attached to its posterior and lateral parts, and
firmly united to it, {les poinfons or os epineux, styloid ov splint
bones). The main bone only is articulated to the pastern,
which may be compared to the first phalanx of the human
finger; as the coffin bone resembles in some degree the third
phalanx, which supports the nail.t This last phalanx is very
various in its form, according to corresponding variations in
its horny coverings, which may consist of a flat nail or claw,
or hoof, &c.

The humerus becomes shorter, in proportion as the metacarpus is
elongated ; so that in animals which have what is called a cannon
bone, the os humeri hardly extends beyond the trunk. Hence the
mistakes, which are made in common language, by calling the carpus
of the horse his fore-knee, &c.

The radius forms the chief bone of the fore-arm in the mammalia,
generally speaking ; the ulna is a small slender bone, terminating
short of the wrist in a point, and often consolidated with the radius,
as in the horse and runwialing onimuls. A few genera, which have
great and free use of their anterior extremity, have the power of pro-
nation and supination. But this power diminishes, as the fore-feet
are used more for the purpose of supporting the body in standing,
and in progression. In this case, indeed, the extremity may be said
to be constantly in the prone position, as the back of the carpus and,
toes is turned forwards.

The lower end of the ulna is larger than that of the radius in
the elephant ; but this circumstance occurs in no other instance.

The radius and ulna exist in the seal, manati, and xvhales, but in a
flattened form.

• J. B. Covolo De Metumurphosi duorum Ossium Pedis in Qtiadniperlilnis aliquot.
Bonon. 1765, 4to. ; and Fougeroux in the M6m. de I'Acad. des Sc. 1772, p. 520.

t The effect of bad shoeing in disfiguring the natural texture of the hoof of the
horse, and the structure of the hoof itself, are well explained by Bracy Clarke in;
hit Seriei of original EiperitneTitf on the Foot of the living Home. Lond. 1S09.

E 2'

62

ON THE SKELETON OF MAMMALIA.

Several genera of mammalia possess a hand ; but it is much less
complete, and consequently less useful than that of the human sub-
ject, which well deserves the name bestowed on it by Aristotle, of the
organ of all organs. The great superiority of that most perfect in-
strument, the human hand, arises from the size and strength of the
thumb, which can be brought into a state of opposition to the fingers,
and is hence of the greatest use in grasping spherical bodies, in tak-
ing up any object in the hand, in giving us a firm hold on whatever
we seize ; in short, in a thousand offices, which occur every moment
of our lives, and which either could not be accomplished at all, if the
thumb were absent, or would require the concurrence of both hands,
instead of being done by one only. Hence it has been justly de-
scribed by Albinus as a second hand " ?na>ms parva majori acljulrix,"
De Sceltto, p. 465.

All the simics possess hands : but even in those, which may be most
justly styled anthropomorphous, the thumb is small, short, and weak ;
and the other fingers elongated and slender. In others, as some of
the cercopitheci, there is no thumb, or at least it is concealed under
the integuments ; but these animals have a kind of fore-paw, which
is of some use in seizing and carrying their food to the mouth, in
climbing, &c. like that of the s(juirrel. The genus lemur has also a
separate thumb. Other animals, which have fingers sufficiently long
and moveable for seizing and grasping objects, are obliged, by the
Want of a separate thumb, to hold them by means of the two fore-
paws ; as the squirrel, rat, opossum, &c. Those, which are moreover
obliged to rest their body on the fore-feet, as the dog and cat, can
only hold objects by fixing them between the paw and the ground.
Lastly, such as have the fingers united by the integuments, or en-
closed in hoofs, lose all power of prehension.

The simicE in general have nine bones in the carpus. Riolani An-
ihropographia and Osteolog. p. 908. Paris, 1626 ; but there are only
eight in the orang-outang, according to Tyson. There are five car-
pal bones in the fin of the whale, of a flattened form, and hexagonal.
The metacarpus is elongated in those animals, where the toe only
touches the ground in standing or walking ; and constitutes the
part, which is commonly called the fore-leg ; as the carpus is termed
the knee.

The number of metacarpal bones is the same with that of the fin-
gers or fore-toes : except in the ruminating animals. Even in thescj
as the author observes, there are two distinct metacarpal bones, lying
close together before birth : the opposed surfaces first become thin-
ner, then are perforated by several openings, and at last disappear ;
so that the adult animal has a single cannon bone, possessing a com-
mon medullary cavity internally, and marked on the outside with a
slight groove at the place of the original separation. There is there-
fore but one metacarpal bone in the adult for the two toes. The
structure of the metatarsus is the same.

In the horse on the contrary, if we allow the spliyit bones to belong

ON THE SKELETON OF MAMMALIA. 53

to the metacarpus, there will be three to a single toe. Daubenton con-
siders the common bone of this animal as supplying the place of the
three metacarpal bones of man ; he compares the outer splint bone to
the metacarpal bone of the little finger, and the inner to that of the
thumb. Stubbs views the cannon as the metacarpal of the middle
and ring fingers ; and the inner-splint as that of the fore-finger.
BufFon, Hist. Naturelle, 4to. ed. p. 362, vol. iv. Stubbs's Analomy of
the Horse.

The single finger or fore-toe of the horse is composed of the usual
three phalanges ; the first, which is articulated to the cannon, is call-
ed t\\e pastern; the 2nd is the coronet; and the 3rd, the os basis or
coffin bone ; on which the hoof rests. There are also two sesamoid
bones at the back of the pastern joint ; and an additional part, called
the shuttle-hone, connected to the coffin.

In those animals which have five toes, as the Carnivora, &c , that
which lies on the radial side of the extremity, and is therefore analo-
gous to the thumb, is parallel with the others ; and the animal conse-
quently has not the power of grasping any object. The last phalanx
in these supports the nail of the animal ; and sends a process into its
cavity. These parts are so connected that the nail is naturally turn-
ed upwards, and not towards the ground ; so that its point is not in-
jured in the motions of the animal. The phalanx must be bent in
order to point the nail forwards or downwards.

The order oi rodenlia have generally five toes ; that which corres-
ponds to the thumb being the shortest.

The elephant has five complete toes ; but they are almost concealed
by the thick skin.

The pig has four toes ; two larger ones, which touch the ground *,
and two smaller behind these, which do not reach so far. There is
also a bone, which seems to be the rudiment of a thumb.

The phalanges of the cetacea are flattened, not moveable, and join-
ed together in the fin.

§ 46. I have something to say respecting the posterior ex-
tremities. The femur of most quadrupeds is much shorter
than the tibia, and hence it hardly projects from the abdomen.
In some few, as the bear, the femur is longer ; this is also the
case in some apes, viz. the orang-outang, in which, as in se-
veral other apes and baboons, the bones of the arm and fore-
arm are surprisingly longer than those of the thigh and leg.
Some, as the elephant, have no ligamentum teres ; conse-
quently there is no impression made on the head of the thigh-
bone, while it is found in others, as the rhinoceros. The pe-
cora want the fibula almost universally. The peculiar form of
the astragalus, (talus) in the same order is generally known

o4! ON THE SKELETON OF MAMMALIA.

from the use which the ancients* made of the bone in their
celebrated game. In some quadrumana, as the orang-outang,
the two posterior phalanges of their toes are remarkably
curved in their shape ; a structure which enables them to hold
the branches of trees more firmly, and is in the same degree
unfavourable to the action of progression in an erect position.
Cetaceous animals have no bones in their tail fins, but they
have a bony compages in their thoracic fins, which completely
resembles the front extremities of the seal. This is also the
case with the manati, whose front extremities were formerly
taken for Sirens' hands.t

The length of the femur depends on that of the metatarsus ; and it
bears an inverse ratio to the length of that part.

Hence it is very short in the hurse, cow, &c. where the same mis-
takes are commonly committed in naming the parts, as in the anterior
extremity.

The proportions of the thigh and leg vary in different animals. The
latter part exceeds the former in the human subject ; and the same
remark may be made respecting the arm and fore-arm. These parts
are nearly of the same length in the orang-outang. Some persons
have affirmed that the negro forms a connecting link between the
European and the orang-outang in these respects. (White on the re-
gular Gradation in Man and Animals, &c.) In some other simiae the
leg and fore-arm exceed the thigh and arm. In other animals, although
there are some varieties, the leg is generally longer than the thigh.

The femur of the mammalia is not arched as in the human subject :
it possesses scarcely any neck ; and the great trochanter ascends be-
yond the head of the bone.

The fibula is behind the tibia in many animals, as the dog and the
rodentia. It is consolidated to that bone at its lower end in the mole
and 7'at. It only exists as a small styloid bone in the horse, and be*
comes anchylosed to the tibia in an old animal.

The structure of the metatarsus in the ruminating animals, and the
horse, is the same with that of the metacarpus.

The tarsus of the Iiorse is composed of six bones ; and is the part
known in common language by the name of the hock.

Animals of the genus simia and lemur, instead of having a great toe
placed parallel with the others, are furnished with a real thumb, i. e.

* Aristotle, Hist. Anim. 1. 2, c. 1 ; and Be partibus Animal. 1. 10, c. 4. For the
vaiious appellations of this well known bone in most of the European and Oriental
languages, and for its form in different animals, see Th. Hyde, Historia Talorum, in
the 2ad vol. of his Syntagma Dissertationum. Oxoa. 1767, 4to. p. 310.

t Bartholin. Hist. Anat. cent. 2, p. 188.

ON THE SKELETON OF MAMMALIA. 55

a part capable of being opposed to the other toes. Hence these ani-
mals can neither be called biped, nor quadruped, but are really quad-
rumanous or four-handed. They are not destined to go on either two
or four extremities, but to live in trees, since their four prehensile
members enable them to climb with the greatest facility ; so that Cu-
vier has denominated them " les grimpeurs par excellence." (Lefons
d'Anat. comp. vol. i. p. 493.) The prehensile tail of several species
is a further assistance in this way of life. The opossum, and others of
the genus didelphis, have a similar structure with the quadrumuna ;
and it answers the same purpose. Here however there is a separate
thumb on the posterior extremity only, whence Cuvier calls them pe-
dimanes.

Man is the only animal, in which the whole surface of the foot
rests on the ground ; and this circumstance arises from the erect sta-
ture which belongs exclusively to him. In the quadrumuna, in the
hear, hedgehog, and shreiv, (which are called by Cuvier plantigrades)
the OS calcis does not touch the ground.

The heel of a species of bear belonging to this country, viz. the
badger, {ursns meles) is covered with a long fur, which proves that this
part cannot rest on the ground ; although the structure both of the
bones and muscles of the lower extremity of this animal, approaches
considerably to that of man. The same fact is stated of the bear it-
self, properly so called, in the Description anatomique d'un Cameleon,
d'un Castor, d'un Ours, &c. Paris, 1669, 4to. ; the plate is contained
in Blasius's Collection, tab. 32.

In other animals the body is supported upon the phalanges of the
toes, as in the dog and cat ; in the horse and ruminating animals no
part touches the ground but the l?st phalanx. Here the elongation
of the metatarsus removes the os calcis to such a distance from the
toe, that it is placed midway between the trunk and hoof.

CHAPTER III.

ON THE SKELETON OF BIRDS.

§ 47. The skeleton* of birds has considerable uniformity in
the whole class ; and it exhibits, when compared with the va-
riously formed skeletons of mammalia, a very great and unex-
pected similarity to that of the human subject.t

§ 48. The skull of birds is distinguished by this peculiarity,
that the proper bones of the cranium,| at least in the adult
animal, are not joined by sutures, but are consolidated as it
were into a single piece.

A peculiarity, which seems to be confined to the cormorants^
must be here mentioned. There is a small sabre- shaped bone
at the back of its vertex, which is supposed to serve as a lever
in throwing back the head, when the animal tosses the fishes,
which it has taken, into the air, and catches them in its open
mouth. But the same motion is performed by some other
piscivorous birds, who are unprovided with this particular
bone.§

Birds have, without exception, only a single condyle, placed
at the anterior margin of the great occipital foramen.

There is also, in the whole class, a bone of a somewhat

* See Nitzch, Osteograßsche Beyt. zur N. G. der Vögel. Leips. 1811 ; and Tiede-
mann's Zoologie, torn. ii. and iii.

f As that excellent naturalist Belon has already shewn in his Histoire de la Na-
ture des Oiseaux avec leurs Naifs Portraits retirez du Naturel. Paris, 1555, fol.
p. 40.

t Consult on this subject Vine. Malacarne, Of the Parts relating to the Brain of
Birds^ in the Memoirs of the Italian Society, torn. i. and ii. ; and Geoff. St. Hilaire,
in the Annal. du Museum, torn. iii. cah. 58.

§ The whole skeleton of the cormorant is represented by Goiter in the 4th of his ex-
cellent plates, which are attached to his edition of the Lectiones Fallopii de partibus
similarihus, &c, Norib. 1575, folio.

ON THE SKELETON OF BIRDS. 57

square figure, (called by the French os carrt)* by which the
lower jaw is articulated with the Cranium on both sides, in the
neighbourhood of the ear.

The ossa unguis are common to birds with mammalia, but
appear to be more general in the former than in the latter :
they are of considerable size, and must be distinguished from
the superciliaryt bones which probably belong to the acci- .
pitres, or predacious birds, only.

The cranial bones of birds form, as might be expected, a link
between those of the amphibia and the mammalia. The number
of the separate bones on the sides and the base of the cranium is
greater in birds than in the mammalia. The principal difference be-
tween the head of birds and that of man and other mammalia is, that
the cranial bones of the former are less developed, whereas, on the
contrary, they are more completely separated and fully developed in
the latter. Hence all the bones of the skull in birds unite in one
piece, and lose their individuality. The large bones of the face and
of the beak project forward under the small skull. This enlargement
of the face is effected by several bones, which in man and mamma-
lia only exist on parts of the cranial bones ; for instance, the lesser
alae of the sphenoid bones in birds are separated from the skull, and
become facial or beak bones.

The single condyle placed at the anterior margin of the great oc-
cipital foramen, gives the head a great freedom of motion, particu-
larly in the horizontal direction. It enables the bird to place its bill
between the wings, when asleep ; a situation, in which none of the
mammalia can bring the snout.

The OS quadratum has a true articulation both with the lower man-
dible and with the cranium. Another small bone is connected to it,
and rests by its opposite end against the palate. Hence, when the
square bone is brought forwards, which it is by the depression of the
lower mandible, and in a greater degree by some particular muscles,
the second bone presses against the palate, so as to elevate the upper
jaw.

§ 49. The jaws are wholly destitute of teeth.J The supe-
rior maxilla, which is completely immoveable in mammalia,

• Herissant has given it this name in the Mem. de I'Acad. des Sc. 1748. But
Goiter has pointed it out in the work before quoted.

f See Merrem's Obiervnlions relating to Zoology, p. 120.

i In the upper jaw of some birds, modern zootomists have detected a rudiment of
the maxillary bone. See Fischer's Monograph, p. 115 j and Geoff. St. liilaire, in the
Annates du Museum, \xim, X, p. 3^7.

58 GN THE SKELETON OF BIRDS.

has, with a few exceptions, more or less motion in birds.* It
either constitutes a particular bone, distinct from the rest of
the cranium, to which it is articulated, as in the psittaci\
(birds of the parrot kind) ; or it is connected into one piece
with the cranium, by means of yielding and elastic bony plates ;
as is the case with birds in general. It is quite immoveable in
very few instances ; as in the rhinoceros bird (at least in that
which I possess in my collection).

Respecting the question which has been recently agitated,
whether in the flamingo the upper jaw only is moveable,
and on the contrary the lower one perfectly immoveable ; I
can state that in the skull of this bird which I have now be-
fore me, this is in no way the case4

The bill of birds may be considered, in some degree, as supplying
the place of teeth. It consists of a horny fibrous matter, similar to
that of the nail, or of proper horns ; and is moulded to the shape of
the bones, which constitute the two mandibles, being formed by a soft
vascular substance, covering these bones. Its form and structure are
as intimately connected with the habits and general character of the
animal, as those of the teeth are in the mammalia.

The bill is of extraordinary hardness in birds which tear their prey,
as in eagles, or in those which have to bruise hard fruits, as parrots^
or in those which penetrate the bark of trees, as the woodpecker, nut-
hatch, &c.

This hardness is gradually diminished in those which take less so-
lid nourishment, or which swallow their food whole ; and the bill be-
comes a portion of nearly soft skin in those which require a sense of
feeling in the part to enable them to obtain their food in mud, or
water, as in ducks, woodcocks, snipes, &c.

Many birds, especially birds of prey and the gallinaceous tribe, have
the base of the bill covered with a soft skin called cire, the use of
-which is not known.

As the bill of birds is at the same time the organ of prehension
and manducation, it has an important influence on their character
and habits. Cceteris paribus, there is greater strength in a short than
in a long bill, in a thick and solid, than in a thin or flexible one ;

* Herissant Sur Us Mouvemens du Bee des Oiseaux, in the Mem, de I' Acad, des
Sciences, 1748, p. 345, with excellent plates.

f Labillardiere says also of the upper mandible of the pelicanus varius, " Cette
mandibule est mobile, comme celle des perroquets." Relation du Voyage, &c. i. p.
210.

t BufFon, Hist. Nat. des Oiseaui, vol. xvi. p.'300, ed. in 12mo.

•ON THE SKELETON OF BTUDS. 59

but the general form produces infinite variety in the application of
force.

A bill hooked at the end with sharp edges characterises birds of
prey, whether those which prey on the smaller birds and quadrupeds,
or those which prey on fishes, as the albatross, the petrel, &c. The
former have a shorter beak, and proportionally greater strength. A
tooth-like process on each side adds greatly to the strength of such a
bill ; hence the birds which are provided with these processes are
considered more noble and courageous than the birds of prey which
want them. The shrike, which possesses them, scarcely yields in cou-
rage to the common birds of prey, notwithstanding its small size, and
the weakness of its wings and feet. When the hooked bill tapers to-
wards the end, it approximates to the knife-shaped bill, which is pe-
culiar to semi-predacious birds, birds of carrion, crows, pies, &c.
The knife-shaped bill indicates a character similar to that of aquatic
birds, such as the grebe, gull, &c.

Another species of strong sharp-edged bill, of an elongated shape,
but without a hook, serves to cut and break, but not to tear. This
is the form of the bill in birds which live upon animals which make
resistance in the water, as reptiles, fishes, &c. Some of these bills are
quite straight, as in the heron, the stork ; some are curved towards
the bottom, as in the tantalus, or towards the top, as in thejabiru.

Some sharp- edged bills have their sides approximatino-, like the
blade of a knife to its handle, and can only serve to seize small sub-
stances ; of this description is the bill of the penguin, the puffin (where
it has the further peculiarity of being as deep as it is long) and the
cut-water, in which another singular circumstance is observed, namely,
that the upper mandible is shorter than the lower, so that the bird can
only seize substances by pushing them before it, as it skims along the
water. Lastly, there are some sharp-edged bills, which are flattened
horizontally ; they serve to seize fishes, reptiles, and other large ob-
jects. The boat-bill has a bill of this description, which is also fur-
nished with tooth-like processes, ^ome fly -catchers and green todies
have a similar structure on a minute scale.

Of the bills, of which the edges ai'e not cutting, some are flattened
horizontally. When they are long and strong, they serve for swal-
lowing prey of large dimensions, but which makes little resistance.
When they are long and weak, as in the spoon-bill, in which the flat-
tened extremity of this part gives the name to the bird, they serve
only to imbibe small objects in the mud or water.

The bills of clucks, which are in some degree flattened, the more
conical ones of geese and swans, and that of the flamingo, of which
the upper mandible crosses the lower, have all transverse laminae
ranged along their edges, which, when the bird has seized any
thing in the water, give passage to the superfluous fluid. Thus aU
these birds are aquatic. In the goosanders, which in other respects
partake very much of the nature of ducks, these laminae become
small, conical, tooth-like processes, which are well adapted for hold-
ing fish, of which the goosanders destroy great numbers. Wholly

60 ON THE SKELETON OF BIRDS.

different from these are the long, thin, soft bills, peculiar to birds
•which derive their food from animals in mud or stagnant waters.
They are straight in the snipe, hooked towards the end in the curlew,
and towards the top in the avocette.

The bills of the toucan and the calao are remarkable for their
extraordinary size, which is sometimes equal to that of the whole
bird. The osseous substance of these bills is of an extremely light
cellular texture, without which they would be incapable of maintain-
ing an equilibrium in their flight. The horn which covers them is
so fine as to become irregularly indented on its edges, by the use
which the bird makes of it. In addition to their enormous bills, the
calaos have prominences upon them of the same substance, and of
various forms, the use of which is not known. The calao rhinoceros
is the most remarkable in this respect, as it appears to have two
enormous bills, one over the other.

The wood-peckers have a long, strong, prismatic bill, compressed
at the end, which enables them to penetrate the bark of trees. That
of the king-fisher is nearly similar ; but being much longer in pro-
portion to the size of the bird, it cannot serve the same purposes ;
besides, the tongue, which is of great importance in determining the
use of the bill, is altogether different.

The short, conical, arched bill of the gallince sei'ves only to take up
grain and similar substances, which they swallow so quickly that
small pebbles are frequently united with their food. These birds, in
an unconfined state, feed on insects as well as grain; indeed the
young ones, in many species, live for some time exclusively on insects.

The bills of the smaller birds (passeres) present all the varieties of
the conical form, from the broad-based cone of the hawfinch to the
-thread-like cone of the humming-bird. Such of them as have a
short strong bill live on grain ; those with a long, thin bill, on
insects. Where this weak bill is short, flat, opening very ante-
riorly, as in martins and swallows, the bird seizes flies and butterflies
in the air ; if it be long and curved, possessing some strength, as in
the hoopoe, it grubs up worms for its food. The tubulated tongue
of the humming-bird is capable of being elongated so as to enable it
to suck up honey from the calices of flowers.

Of all bills the most extraordinary is certainly that of the cross-bill,
in which the two mandibles cross each other at a considerable angle,
for this formation seems to be directly opposed to the natural pur-
poses of a bill. The bird, however, contrives to pick out the seeds
from the cones of the fir, and it is limited to that species of nourish-
ment.

^ 50. The proportionate magnitude of the bones of the
cranium and jaws varies much in this class. The former are
large in the owl; the latter are of vast magnitude in the rhi'
noceros bird. A most remarkable sexual difference appears

ON THE SKELETON OF BIRDS. 61

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 unpa-
ralleled in the whole animal kingdom.* I have lately examined
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 cerebrum ; and it is separated from the
posterior pai't which holds the cerebellum, as in the common
hen, by an intermediate contracted portion.

§ 51. One of the peculiar characteristic differences of the
cranium of birds when compared to each other,+ consists in
the mode of separation of the orbits, which are of great size
n the whole class. In some they are separated by a mem
branous partition only ; in others by a more or less complete
bony septum. The relation which the nasal and palatine
openings bear to the upper jaw varies much, even in the diffe-
rent species of the same genus. They are small in the stork,
and on the contrary, so large in the crane, that the longest
portion of the jaw appears to consist merely of three thin por-
tions of bone, placed far apart from each other, and converging
towards the point of the bill.

§ 52. The want of motion in the back of birds, (their dorsal
vertebrae have the spinous, and even the transverse processes,
often anchylosed) is compensated by a larger number, and
greater mobility of the cervical vertebrae ; of which, to quote
a few instances, the raven has 12, the cock 13, the ostrich 18,
the stork 1 9, and the swan 23.

§ 53. The trunk of birds has fewer cartilaginous parts than
the corresponding division of the skeleton in mammaha. That
part of the spine which belongs to the trunk is short and
rigid, and has no true lumbar vertebrae. Neither has any
bird an os coccygis prolonged into a true jointed tail. In the
frallus ecaudalus, in which the rump has been lost by de-
generation, there is nothing more to be seen of the coccyx
than an unshapely knotty process.

• See Pallas, fasc. 4, Act. Acad. I>etr(ypolil, 1780, part 2, p. f)7.
t See J. T. Klein, .Stemmata Amum, Lips. 1759, 4to.

62 ON THE SKELETON OF BIRDS.

The number of cervical vertebras in birds varies from ten to
twenty-three ; those of the back from seven to eleven. From hence
to the tail they are consolidated into one piece with the os innomi-
natum. The tail has from seven to nine pieces.

The length of the neck increases generally in proportion to that of
the legs ; but in aquatic birds in a much greater proportion, since
they have to seek their food below the surface of the water on which
they swim.

The cervical vertebrae are not articulated by plane surfaces, but by
cylindrical eminences, *vhich admit a more extensive motion, as they
constitute real joints, instead of synchondroses. Four or five of the
upper pieces only bend forwards, while the lower ones are confined
to flexion backwards. Hence the neck of a bird acquires that dou-
ble bend, which makes it resemble the letter S. It is by rendering
the two curvatures more convex, or more straight, that the neck is
shortened or elongated. The great mobility of the neck enables birds
to toucli every point of their own body with the bill, and thus to
supply the want of the prehensile faculty of the superior extremity.
The atlas has the form of a small ring, which articulates with the
head by only one surface. In proportion to the mobility of the neck
of birds is the fixed state of the dorsal vertebrae, which are connected
together by strong ligaments. The greater part of their spinous
processes are consolidated into a single piece, which runs like a ridge
along the whole back. The transverse processes terminate in two
points, one directed anteriorly, the other posteriorly ; they meet
those of the two other classes of vertebrae, sometimes anchylosing
with them, as the spinous processes do with each other. This struc-
ture is necessary to give steadiness to the trunk in the violent
motions required by the action of flying. Accordingly birds which
do not fly, as the ostrich and the cassowary, have a moveable spinal
column.

The vertebrae of the tail are most numerous in those birds which
move it with the greatest force, as the magfie and the swalloxv. They
have inferior as well as superior spinous processes, aiad the transverse
processes are long. The last is the largest, and has the shape of a
ploughshare, or flattened disk. The cassoixary, which has no visible
tail, has this last bone ; in the peacock, it has the shape of an oval
plate, situated horizontally.

§ 54. The pelvis of birds is chiefly formed by a broad and
simple OS innominatum ; the lateral portions of which are of
different figures in the several genera ; but, instead of uniting
below to constitute a symphisis pubis, they are quite distant
from each other. The ostrich alone forms a remarkable ex-
ception to this rule, inasmuch as its pelvis, like that of most
quadrupeds, is closed below by a complete junction of the
ossa pubis.

The pelvis of birds consists of the same bones as that of man. Tiie

ON THE SKELETON OF BIRDS, 63

length and breadth of the pelvis vary in different classes of birds ; it
is broadest and most developed posteriorly in the gallinaceous birds,
which seldom fly and generally go erect. The pelvis is small and
short in birds of prey ; that of the passeres, pici, and levirostres holds
a middle place between the pelves of the gallinaceous hirds and the
birds of prey. In the unseres, (hwimming birds) the pelvis is very
much elongated. It is particularly small and laterally compressed in
some of the gralloe, so that the ossa innominata and sacrum form a
kind of keel. In the ostrich and cassowary the pelvis is closed ante-
riorly, and resembles that of mammalia.

§ 55. Birds have fewer ribs than mammalia ; the number, I
believe, never exceeds ten pairs. The false ribs, i. e. those
which do not reach to the sternum, are directed forward ; the
true ones are joined to the margin of the sternum by means
of small intermediate boiies. The middle pairs are distin-
guished by a peculiar flat process, which is directed upwards
and backwards.

§ 56. The sternum of these animals is prolonged below into
a vertical process, {crista) for the attachment of the strong
pectoral muscles. In the male wild swan {anas cygnus) and
in some species of the genus ardea, as the crane, this part
forms a peculiar cavity for the reception of a considerable por-
tion of the trachea. The crista is entirely wanting in the
ostrich and cassowary ; where the sternum presents a plane
and uniformly arched surface. This peculiarity of structure
is accounted for by observing, that these birds have not the
power of flying. The wings, which are very small, assist in
balancing the body as they run.

§ 57. The wings are connected to the trunk by means of
three remarkable bones.* The clavicles, which are always
strong, constitute straight cylindrical bones. Their anterior
extremities are connected to the sternum by means of a bone
peculiar to birds ; viz. the fork-like bone, or, as it is more
commonly termed, the merry thought. {Furcula, or osjugale,
in Latin, la lunette, or fourchette, in French.) The ostrich

* FoT an account of several differences in their structure, see Vicq d'Azyr in his
Mimoiref pmr seri'ir a V Anatomie dff Oimnir, in thr. M^m. <Je VAcad. den Sc. 1772, p.
626.

64 ON THE SKELETON OF BIRDS.

and cassowart/ have indeed no seiparate furcula ; but on either
side of the front of the chest an elongated flat bone, consist-
ing of a rudiment of the furcula, with the clavicle and scapula
consolidated into one piece.*

The point of the fork-like bone is joined to the most prominent
part of the keel of the sternum ; and the extremities of its two
branches are tied to the humeral end of the clavicles and the front
of the scapulae, just where these bones join each other, and are
articulated with tlie humerus. Hence it serves to keep the wings
apart in the rapid motions of flying. " As a general observation it
may be stated, that the fork is strong and elastic, and its branches
wide, arched, and carried forwards upon the body, in proportion as
the bird possesses strength and rapidity of flight ; and accordingly
the slruthious birds, {ostrich and cassowary) which are incapable of
this mode of progression, have the fork very imperfectly formed.
The two branches are very short, and never united in the African
ostrich, but are anchylosed with the scapula and clavicle. The casso-
wary has mei'ely two little processes from the side of the clavicle,
which are the rudiments of the branches of the fork. In the New
Holland ostrich there are two very small thin bones, which are at-
tached to the anterior edge of the dorsal end of the clavicles by
ligament ; they are directed upwards towards the neck, where they
are fastened to each other by means of a ligament, and have no con-
nexion whatever with the sternum."

Macartney, in Rees's Cyclopaedia. Article Birds, Anatomy of.

§ 58. The bones of the wing may be compared on the whole
to those of the upper extremity in man, or the quadrumana ,•
and consist generally of an os humeri ; two bones of the fore-
arm ; two of the carpus ; two, which are generally consolidated
together, of the metacarpus ; one bone of the thumb; and
two fingers ; of which that which lies towards the thumb con-
sists of two phalanges, the other only of one. The most
remarkable deviation from this structure, in respect to the
number, as well as the formation and relative proportion of the
bones, is found in the fin-like wings of the penguin.f All
the bones are here of a very remarkable flattened form, as if
they had been pressed ; there are two supernumerary bones

* See De Fremery, Observ. Osteologica de Casuurio Novce Hollandite. Ultraject.
1819, p. 25.

t On the wing of the owl, see Heusinger, in Meckel's Deutsch, Archiv, vol. vii. p.
177.

ON THE SKELETON OF BIRDS. 65

at the elbow, and the bone of the thumb is entirely want-
ing.

§ 59. The bony structure of the lower extremities is more
simple in birds than in mammalia. In general it comprehends
only the following bones, viz. the femur, the tibia, (to which,
in some instances, is added a small, thin, closely adhering
pointed fibula), one metatarsal bone, and the toes. On the
metatarsal bone of the domestic cock and other birds of the
gallinaceous tribe, the spur is situated, a process covered with
horn, between which and the genital organs a peculiar sym-
pathy is supposed to exist.* The place of the patella is sup-
plied, in many cases, by a process of the tibia. As birds have
neither a true fibula, nor tarsus, their tibia is immediately ar-
ticulated with the metatarsus. There is, in most of this class,
a peculiar progressive increase in the number of phalanges of
the toes : the great toe has two ; the next, three ; the middle
one, four ; and the outer one, five.-j- The psittaci have, how-
ever, a peculiar cross-bone belonging to the great toe ; at
least I have found it in several skeletons of psittaci in my
collection. That in the psittacus erithacus resembles a short
cylindrical bone ; in the psittacus leucocephalus its formation
is rounder.

Birds certainly have a fibula, contrary to the general assertion of
the author ; but it is small, and soon anchylosed to the tibia.

The lower end of the bone, which answers to the tarsus and meta-
tarsus, forms as many processes as there are toes ; and eacli of these
has a pulley for articulation with its corresponding toe.

The vast length of the leg in the wading birds, (grallce) the ostrich
and cassowary, is produced by the tibia, and common bone of the
tarsus and metatarsus ; for the femur is comparatively short.

The stork, and some others of the grallcB, which sleep standing
on one foot, possess a curious mechanism for preserving the leg in a
state of extension, without any, or, at least, with little muscular
effort. There arises from the fore-part of the head of the metatarsal
bone a round eminence, which passes up between the projections of

• See Oslander, in Beckman's Beytrage zur Geschichte der Erfindungen, vol. v. s.
499.

+ Several excellent remarks on this, as well as other parts of the osteology of this
class, may be found in Professor Schneider's instructive work, Commentar. ad reliqua
JAbrorum Fredcrid 2ndi Itnperatoris, p. 30.

F

'.m

66i ON THE SKELETON OF BIRDS.

the pulley, on the anterior 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 the 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 bird to overcome, which being accomplished,
it slips in with some force, like the end of a dislocated bone.
Macartney, loco citato.

67

CHAPTER IV.

ON THE SKELETON OF AMPHIBIA.

§ 60. The general form of the body, and consequently the
structure of the skeleton, varies so much, in the first place, in
the two orders of this class, viz. the four-footed amphibia and
the serpents; and, secondly, in the three leading classes of
the first order, namely, the testudines, the frogs, and the
U%ards; that it will be best to arrange our observations on this
subject according to the natural divisions of the orders and
classes.

§ 61. The testudines, (turtles and tortoises) whose whole
skeleton,* and indeed whose whole body has a very peculiar
structure, are entirely toothless ; they have, however, a kind
of OS intermaxillare in the upper jaw. The horny covering of
the jaws, particularly the upper one, has some resemblance to
the horse's hoof, in the mode of its connexion with the jaw.
The cavity, containing the brain, is extremely small, in com-
parison with the size of the skull ; the greatest part of which,
in the turtle, is occupied by the large lateral foss«, holding
the eye and the powerful muscles that move the lower jaw.f

This circumstance is still more remarkable in the crocodile. The
cranium of an individual, measuring thirteen or fourteen feet, will
hardly admit the thumb ; and the area of its section does not consti-
tute the twentieth part of that of the whole head.

The chameleon affords another instance of the same structure : its
brain, according to the description of the Parisian dissectors, does

* Good representations of the whole skeleton may be found in Goiter, Cheselden,
and particularly in J. D, Meyer's Pastimes, with Considerations of curious Bepresenta.
tio,i, of all kinds of Animals, &c. vol. i. p. 29, vol. ii. p. 62. The individual parts
are represented in Giov. Caldesi's Anatomical Observations relating to Turtles. Florence
1687, 4to.

t A manerly delineation and description of the skull of the testudo is given by
Dr. Ulrich in his work before quoted.

V 9.

68 ON THE SKELETON OF AMPHIBIA.

not seem larger than a pea; and the whole head, which is of consi-
derable size, consists of the large maxillary bones, the orbits, and
immense temporal fossae, which, not being separated by any partition,
give the cranium a very singular appearance.

See the Description anatomique d'un Cameleon, &c. or Blasius's
Collection, tab. 14.

§ 62. The trunk is consolidated with the two great shells
of the animal; the dorsal vertebrae and ribs being attached to
the upper, the sternum being fixed in the lower or abdominal
shell. The upper bony covering, or that of the back, consists
of about fifty pieces, which are partly connected together by
real sutures.

§ Q>S. The same bones are found in the pelvis of these ani-
mals, as in the mammalia ; but the proportion of their relative
size is inverted. For instance, the ossa pubis are so deep and
broad, that they form the largest flat bones in the whole ske-
leton, while the ilia are the smallest.

§ 64. The form and position of the scapula and clavicle are
the most extraordinary. The former has a most anomalous
situation towards the under part of the animal, just behind
the abdominal shell ; the latter consists of two pieces, joined
at an acute angle, to which the humerus is articulated.

§ Q5. Frogs and toads* have no real teeth, though the mar-
gin of the jaws is denticulated. Their spine is short, and
terminates behind in a straight and single bone, which is re-
ceived into the piiddle of the somewhat fork-like os innomi-
natum.

§ 0)6, They have no ribs ; but the dorsal vertebrae are fur-
nished with broad transverse processes. The scapula, which
is thin and flat, and a pair of bones, corresponding to the
clavicle, are joined to the sternum.

* Skeletons of the frogs cuid toads of this country (Germany) may be seen in the
well known chef d'ceuvre of Roesel, De Ranis nostratibus. The singular skeleton
of the rana pipa, (Surinam toad) is accurately described and delineated in the first
fascic. of Professor Schneider's Histor. Amphibior. It is particularly distinguished by
the large lateral processes of the sacrum, and by a bony cavity (cista Schneid.^ of
unknown use, placed behind the sternum, and belonging exclusively, as it should
seem, to this animal. See Rudolphi, in F. G.Breyer's Obs.AnaU circa fabricam Rante
Pipo", Berol. 1812 ; also the Ranu Paradoxa, by Lorenz j ajid C. H. Merten's Obs.
in Ostenlogiam Batrachorum nostratium. Hal. 1820,

ON THE SKELETON OF AMPHlBlAi 69

§ 67. The bones of the fore-arm and of the leg have a
peculiarity of structure, in these animals, which deserves no-
tice. These bones consist of a single piece, which is solid
in the middle, without any medullary cavity, but divided at
either extremity into two conical portions, having manifest
medullary cavities.*

§ 68. Among the amphibia of the class of lizards, the cro-
codilef may be taken as an example,:^ on account of many
remarkable peculiarities in its structure. In no other animal
are the jaws of such immense size, in comparison with the ex-
tremely small cavity of the cranium. The anterior part of the
upper jaw consists of a large intermaxillary bone, and the
lateral portions of the lower maxilla are formed of several
pieces joined together. The lower jaw is articulated in a pe-
culiar manner in these animals, although the commencement
of this kind of articulation is seen in the jaw of the testudines :
it has an articular cavity, in which a condyle of the upper jaw
is received. The condyle resembles in some measure, the
pulley at the inferior extremity of the humerus, the trochlea,
or rotula of Albinus ; this, at least, is the case in the skull of
an alligator, which I have before me.

The old error of supposing that the upper jaw of the cro-
codile is moveable, and the lower, on the contrary, incapable
of motion, which has been adopted even by such anatomists
as VesaUus and Columbus, has perhaps arisen from this pecu-
liar mode of articulation. An examination of the cranium
shews, that if the lower jaw remains unmoved, the whole
remainder of the skull may be carried backwards and forwards
by means of this joint ; and such a motion is proportionally

* See Troja's Memoir concerning the singular Structure of the Tibia and Ulna in
Frogs and Toads, in his Experiments on the Regeneration of Bones, Naples, 1779, p.
250.

t The skeleton of the crocodile is represented in N. Grew's Museum Regalis Socic'
tatit. Lond. 1681 ; also in Faujas St. Fond, Histoire Naturelle de la Montague de
St. Pierre de Maestricht.

t The skeleton of the common green lizard may be seen in Coiter, pi. 4 ; Meyer,
torn. i. pi. 56 ; that of the salamander and water-newt are also given in Meyer ; that
of the chameleon is prefixed to Cheselden's 6th ch.

70 ON THE SKELETON OF AMPHIBIA.

easier in the present instance than in any other animal, both
on account of the very great relative size of the lower jaw, as
well as from its anomalous mode of articulation. There is,
however, no motion of the upper jaw-bone only, similar to that
which occurs in most birds, serpents, and fishes.

I 69. The numerous teeth of crocodiles have this peculiarity
of structure, that in order to facilitate their change, there are
always two, of which one is contained within the other.*

§ 70. But the most surprising singularity in the skeleton of
the crocodile consists in an abdominal sternum, which is quite
different from the thoracic sternum, and extends from the en-
siform cartilage to the pubis, apparently for the purpose of
supporting the abdominal viscera. In the skeletons of three
East Indian crocodiles which I have examined, there were
ten pairs of true, and two of false ribs. The former had
bony appendages ; and there was a third intermediate portion
between the chief piece of the rib and each appendix. The
abdominal sternum consisted of seven pairs of cartilaginous
arches connected together. The six front pairs were inter-
rupted by open intervals ; and the space between the last
pair and the pubis was filled by a broad piece of cartilage.+

§ 71. The serpents:]; have an upper jaw, unconnected with
the rest of the skull, and more or less moveable of itself.

§ 72. We find in their teeth the important and clearly de-
fined difference, which distinguishes the poisonous species of
serpents from the much more numerous innoxious tribes.

The latter have, in the upper jaw, four maxillary bones, be-
set with small teeth, which form two rows, separated by a
considerable interval from each other. One of these is placed
along the front edge of the jaw ; the other is found more in-
ternally, and is situated longitudinally on either side of the
palate.

* Sometimea three, according to Retzius, Animadvers. circa Crocod. 1797, 4to.

t A somewhat similar structure in the crocodile of the Nile is described by S. Ves-
lingius, in his Observ. Anat. p. 43; and in the alligator, by Plumier, in the Me-
n%oires de Trevoux, of' January, 1705, p. 127.

4: Skeletons of several snakes are contained in the work of Meyer^above quoted»

ON THE SKELETON OF AMPHIBIA. jfj

The external row is wanting in the poisonous species ;
which have, in their stead, much larger tubular fangs con-
nected with the poison bladder, and constituting, in reaKty,
bony excretory ducts, which convey the venom into the wound,
inflicted by the bite of the animal.*

§ 73. It appears, in general, that the number of vertebras in
red-blooded animals, is in an inverse proportion to the size
and strength of their external organs of motion. Serpents,
therefore, which entirely want these organs, have the most
numerous vertebrae ; sometimes more than 300.

The last vertebras of the tail, in the rattlesnake, are
broad, and covered by the first hollow pieces of the horny
rattle : the succeeding portions of this singular and mysteri-
ous organt are connected to each other in a most curious
way.

It raay be observed, in confirmation of the remark, with respect
to the relation between the vertebrae and the external organs of mo-
tion, that the number of vertebrae is very great in fishes of an elon-
gated form, viz. in the eel, which has above one hundred. The por-
poise, which has no organs of motion which deserve mentioning, has
between sixty and seventy.

Birds which have such vast power of locomotion by means of their
wings, have very few vertebrae, if we consider the anchylosed ones
as forming a single piece ; and the frog, with its immense hinder ex-
tremities, has a very short spine, consisting of still fewer pieces.

With regard to the peculiar organ of the rattle-snake above al-
luded to. Dr. Mead's supposition is by no means improbable, that it
may serve to bring birds, &c. within their reach, from the effects of
fear its sound produces, in the same manner that the horns of the ce-
rastes were formerly imagined, and probably not without justice, to
be employed. Major Gardner, a correct and faithful observer, who
had long Hved in East Florida, affirms, that the young Indians of
that country were accustomed to imitate the noise of this serpent, for

* Specimens are delineated, for the sake of comparison, in the 4th part of my De-
lineatioits, &c. tab. 37, where the heads of a rattlesnake {crotalus) and a boa, are re-
presented with their mouths open.

t For the probable use of this organ, which belongs so exclusively to the rattle-
tnake ; and for the assistance which it may aflTord to this inactive animal, by draw-
ing towards it the frightened birds, v^which, indeed, may have given rise to the
Btories concerning its supposed power of fascination) see Voigt's Magazine, vol. i. p.
37, On the fa$cinutmg Power of the Rattlesiiake, particularly with respect to a umk of
Dr. Barton's.

72 ON THE SKELETON OF AMPHIBIA.

the purpose of taking squirrels, &c. Vide Blumenbach's Manual of
Natural History, by Gore, p. 142.

§ 74. Of all animals, serpents possess by far the greatest
number of ribs ; which amount, in some, to 250 pairs. It is
necessary to mention here the costce scapulares of the cobra
di cabelo, [coluber naice) which enable the animal to inflate its
neck. This is also the case with other species of the coluber;
namely, the Egyptian coluber haje, which can dilate its neck
yery considerably when enraged.*

Serpents, with the exception of the unguis fragilis, {blind-
worm) are the only red-blooded animals which have no ster-
num.t

The occiput is connected to the atlas by a single condyle in the
crocodile and turtle ; in the lizard and tortoise there is a slight appear-
ance of division into two surfaces ; in the frog and toad there are
two condyles ; and in the serpents there are three articular surfaces
on a single tubercle.

The condyle of the turtle being deeply imbedded in the atlas, the
motions of the articulation must be limited : the protraction and re-
traction of the head in this animal are effected by the flexion and ex-
tension of the vertebrae of the neck.

The lower jaw is articulated with an eminence of the cranium in
the lizards, turtles, frogs, salamanders, blindworms, (unguis fragilis)
and amphishcEna ; besides the crocodile in which the author mentions
it. This bony eminence is compared by Cuvier to the os quadratum
of birds. The lower jaw only is moveable in these animals. Its ar-
ticulation in the turtle is by means of a ginglymus. In all the ve-
nomous serpents the upper jaw is moveable on the head, as in birds :
these animals require as extensive an opening of the mouth as possi-
ble, since they swallow others whole, which are actually larger than
their own body.

Sir Everard Home was led to the discovery of the aid afforded by the
ribs of the whole tribe of snakes in the progressive motion of those
animals by the following circumstances, A coluber of unusual size,
brought to London to be exhibited, was shewn to sir Joseph Bankes ;
the animal was lively, and moved along the carpet briskly ; while it
was doing so, sir Joseph thought he saw the ribs move forward in
succession, like the ribs of a caterpillar.

The fact was readily established, and Sir Everard felt the ribs with
his fingers as they were brought forward ; when a hand was laid flat

* See Home, Philos. Tram. 1804.

t On the part which the ribs perform in the progressive motion of snakes, see Sir
Everard Home, in the Philosophical Tramactions for 1812.

ON THE SKELETON OF AMPHIBIA. 73

under the snake, the ends of the ribs were distinctly felt upon the
palm, as the animal passed over it. This was an interesting disco-
very, as it tended to demonstrate a new species of progressive motion,
and one widely different from those already known.

In the draco volans the ribs form the skeleton of the wings, by
means of which the animal flies, the five posterior ribs being bent
backwards and elongated for that purpose, so that in that instance
the progressive motion is performed by the ribs, but those particular
ribs are superadded for this purpose, and make no part of the organs
of respiration, whereas, in the snake, the ribs are so constructed as to
perform their office with respect to the lungs, as well as progressive
motion.

That ribs are not essential to the breathing of all animals, whose
lungs are situated in the same manner as in snakes, is proved by
the syren having no ribs ; but as this animal has also gills, and can
breathe in water as well as in air, the lungs are not so constantly em-
ployed, and probably a less perfect supply of air to them may suffice.
In animals in general, the ribs are articulated to the back-bone by
means of a convex surface, which moves upon a slightly concave one
formed upon two of the vertebrae, partly on the one and partly on the
other, so that there is a rib situated between every two vertebrae of
the back ; but in the snake tribe, the head of the rib has two slightly
concave surfaces, which move upon a convex protuberance belong-
ing to each vertebrae, so that there is a rib to each of the vertebrae.

One advantage of this peculiarity is, that it prevents the ribs from
interfering with the motion of the vertebrae on one another. The ver-
tebrae are articulated together by ball and socket joints (the ball being
found upon the lower end and the socket on the upper one) and have
therefore much more extensive motion than in other animals. The
muscles, which bring the ribs forward, consist of five sets, one from
the transverse process of each vertebra, to the rib immediately be-
hind it, which rib is attached to the next vertebra. The next set
goes from the rib a little way from the spine, just beyond where the
former terminates ; it passes over two ribs, sending a slip to each, and
is inserted into the third ; there is a slip also connecting it with the
next muscle in succession. Under this is the third set, which arises
from the posterior side of each rib, passes over two ribs, sending a
lateral slip to the next muscle, and is inserted into the third rib be-
hind it.

The fourth set passes from one rib over the next, and is inserted
into the second rib. The fifth set goes from rib to rib. On the in-
side of the chest there is a strong set of muscles attached to the an-
terior surface of the vertebrae, and passing obliquely forwards over
four ribs to be inserted into the fifth rib, nearly at the middle part
between the two extremities. From this part of each rib a strong flat
muscle comes forward on each side over the viscera, forming the
abdominal muscles, and uniting in a beautiful middle tendon, so that
the lower half of each rib, which is beyond the origin of this muscle,
and which is only laterally connected to it by loose cellular mem-

74 ON THE SKELETON OF AMFHIBIA.

brane, is external to the belly of the animal for the purpose of pro-
gressive motion, and that half of each rib next the spine, as far as the
lungs extend, is employed in respiration.

At the termination of each rib is a small cartilage, in shape cor-
responding to the rib, only tapering to the point. Those of the op-
posite ribs have no connexion, and when the ribs are drawn outwards
by the muscles, are separated to some distance, and rest through their
whole length on the inner surface of the abdominal scuta, to which
they are connected by a set of short muscles ; they have also a con-
nexion with those of the neighbouring ribs by a set of short straight
muscles.

These observations apply to snakes in general ; but they have been
particularly examined in a boa constrictor, three feet nine inches
long, preserved in the Hunterian museum. In all snakes, the ribs are
continued to the anus, while the lungs seldom occupy more than one-
half of the extent of the cavity covered by the ribs. These lower ribs
can only be employed for the purpose of progressive motion, and
therefore correspond in that respect with the ribs in the draco volmis
superadded to form the wings.

75

CHAPTER V.

ON THE SKELETON OF FISHES.

§ 75. We should naturally conclude, from observing the great
diversity in the general form of fishes, that the structure of
their skeleton must be equally various.* They agree together,
however, on the whole, in having a spine, which extends from
the cranium to the tail-fin ; and in having the other fins, par-
ticularly those of the thorax and abdomen, articulated with
peculiar bones destined to that purpose. They have in gene-
ral many more bones unconnected with the rest of the skele-
ton, than the animals of the preceding classes.-f'

§ 76. The cranium in several cartilaginous fishes (in the
sJcate for instance) has a very simple structure, consisting
chiefly of one large piece. In the bony fishes, on the contrary,
its component parts are very numerous ; amounting to 80 in
the head of the perch. Most of the latter have a more or less
moveable under-jaw.

§ 77. Great variety in the structure of the teeth is observed
in this class. Some genera, as the sturgeon, are toothless.

* Delineations of the skeleton of most marine fishes are still wanting. A beauti-
ful view of the skate is given by Cheseldeu, in the beginning of his work ; those of
the hream and herring are well delineated and described in Rosenthal's Icthyotomis-
chen Tafeln, pi. 1. Berl. 1812. See Fischer's Zoognosia, vol. i. Mos. 1813. On
the uranoscopus scaber (star-gazer). Meyer has represented the skeletons of twenty-
five fresh- water fishes in the two first volumes of his book, which has been fre-
quently quoted. That of the carp may be seen in Duhamel, Tratte des Peches, (a
part of the great work, entitled Description des Arts and Metiers,) pi. 2, sect. 1, tab. 3.

t There are some excellent remarks on the skeleton of fishes in general, by Prof.
Autenrieth, in Wiedemann's Archives, vol. i. p. 2 ; and by Rosenthal, in Reil's and
Autenrieth's Archiv. Jur die Physiol, vol. x.

On the skeletons of particular orders of fishes, see Vicq d'Azyr, in tlie 7th vol. of
the Memoires jrresentes ä I' Acad, des Sciences. It is translated into German, with re-
marks and additions by Professor Schneider, in his Sammlung von Anatomisch^en
Aufsätzen, und Bemerkungen sur Außdärung der Fisrhhunde. Leiptig, 1795, 8vo.

76 ON THE SKELETON OF FISHES.

Their jaws, which are distinct from the cranium, form a move-
able part, capable of being thrust forwards from the mouth,
and again retracted.

§ 78. Those fishes which possess teeth, differ very much in
the form, number, and position of these organs. Some species
of bream (as the spartfs probato-cephalus) have front teeth
almost like those of man :* they are provided with fangs,
which are contained in alveoli. In many genera of fishes the
teeth are formed by processes of the jaw-bones covered with a
crust of enamel. In most of the sharks, the mouth is furnished
with very numerous teeth for the supply of such as may be
lost. The white shark has more than two hundred, lying on
each other in rows, almost like the leaves of an artichoke.
Those only, which form the front row, have a perpendicular
direction, and are completely uncovered. Those of the sub-
sequent rows are, on the contrary, smaller, have their points
turned backwards, and are covered with a kind of gum. These
come through the covering substance, and pass forward when
any teeth of the front row are lost."!* It will be understood from
this description that the teeth in question cannot have any
fangs.

The saw-fish only {squalus pristis) has teeth implanted in
the bone on both sides of the sword-shaped organ with which
its head is armed.

In some fishes the palate, in others the bone of the tongue
(as in the frog-ßsh), in others (as in several of the rayrkind)
the aperture of the mouth forms a continuous surface of tooth.
One of the most surprising formations about the mouth occurs
in a West Indian species of skate {raia ßagellum) : it is de-
scribed and delineated by Sloane,:]: as the tongue of the ani-
mal. The specimen, which I possess, consists of a flat bone,
about five inches long, two broad, and of the thickness of the

* Augustin Scilla De Corporibus Marinis lapidescentibus. Rome, 1759, 4to.
tab. 2.

t See Herissant in the Mem. de I' Acad, des Sc. de Paris, 1749, p. 155. And W.
Andre, in the Philos. Trans, vol. Ixxiv. p. 274.

I Philos. Trans, vol. xix. p. 674.

ON THE SKELETON OF FISHES. 77

thumb. It is composed of 15 curved portions, connected to-
gether hkewise ; and each of these arches is covered above
with 60 small teeth, which lie close together.

Many fishes have simple teeth of a bony substance, covered by ena-
mel, and probably formed as in the mammalia. These are the most
common, and may be seen in the pike. When the crown has com-
pletely appeared, the root becomes anchylosed to the jaw.

In other cases they adhere to the gum only, or at least to a firm
cartilaginous substance which covers the jaw. This is exemplified
in the shark. These teeth seem not to be formed, as those of the
mammalia are, by the deposition of successive layers one within the
other ; but in a manner more nearly resembling the formation of
bone. They are at first soft and cartilaginous, and pass by succes-
sive gradations into a state of hardness and density not inferior to
that of ivory.

A third kind of teeth consists of an assemblage of tubes, covered
externally by enamel, and connected to the jaw by a softer substance,
which probably sends processes or vessels into those bony tubes.
This is the case with the pavement, as we may call it, of teeth, that
covers the jaws of the skate.

A similar structure is observed in the anarrichas lupus; where the
teeth, composed of bony tubes, are connected to spongy eminences
of the jaws, which may be compared to epiphyses; and on their se-
paration leave a surface like that from w'hich the antler of the deer
falls off.

Besides the two jaws, fishes have teeth implanted in the bones of
the palate ; in that which corresponds to the vomer ; in the os hy-
oides ; in the bones which support the branchiae ; and in those which
are placed at the top of the pharynx. The salmon and pike have
them in all these situations.

§ 79. In the long-shaped fishes with short fins, the spine
consists of a proportionally greater number of vertebrae ; of
which the eel, for instance, has more than 100, and some
sharks even more than 200. The main piece, or body, as it is
called, of these vertebrae, is of a cylindrical figure, with a fun-
nel-shaped depression on both surfaces, and concentric rings,
. which are said to vary in number according to the age of the
animal. The spinal marrow passes above these, in a canal
formed at the roots of the spinous processes.

The ribs are articulated with what are called the dorsal ver-
tebrae in most of the spinous fishes; but in some they are
without this connexion, and in the cartilaginous fishes proper
ribs c.nnnot be said to exist.

78 ON THE SKELETON OF FISHES.

§ 80. Of the peculiar bones which serve as a basis for the
fins, that of the pectoral fin may be compared to the scapula,
and that of the abdominal in some measure to the os inno-
minatum.

I possess a specimen of the singular bone,* relating to this
subject, which for a long time has been considered a very
obscure one. It is thick, of a roundish flat form, and nearly re-
sembling a smooth chestnut in shape and size. It forms on one
side a bony point ; and on the other is articulated, by means of
a very remarkable ginglymus, with two small bones of different
magnitude, and resembhng the point of an arrow. It belongs
most probably to an East Indian cJicetodon (probably to the
chcetodon arthriticus of Schneider); the larger piece being the
basis of the back fin, and the smaller constituting the first ra-
dii of that fin.f

I 81. Lastly, many fishes are furnished with merely muscu-
lar bones {pssicula musculorum of Artedi) which are sometimes
bifurcated, are always situated among the muscles, and facili-
tate their motion.

* It has been represented in the Museum Wormianum, in the Museum, Regium of
Jacobaeus, and in Olearius, Gottolf. Kunsikammer.

+ See W. Bell's Description of a Chatodon, called by the Malays, Ecan Banna, in
the Philos. Trans. 1793.

79

CHAPTER VI.

ON THE (ESOPHAGUS AND STOMACH.

§ 82. After the comparative view which we have now taken
of the skeleton, as influencing the general form of the red-
blooded animals, we proceed to consider the other parts of the
animal structure, and their functions, according to the natural
order and series of those functions. The particular classes of
animals will be considered in the subdivision of each chapter,
according to the arrangement most usually followed in teach-
ing zoology.

§ 83. The natural functions, as they are called, which in-
clude, in their most extensive sense, the whole process of nu-
trition, very properly take the lead on this occasion. In the
first place, they exist in all classes of animals without excep-
tion, though under various modifications ; they are indeed
common to plants and animals : secondly, the peculiar mode
in which they are performed constitutes the most distinguish-
ing character of animals. For they seek their food by volun-
tary motion, and convey it into the stomach through a mouth.
Partial exceptions to this general rule may be drawn, 1st,
from those animals in which no mouth has hitherto been dis-
covered ; for instance, some animalcula infusoria, and in a
certain sense some medusce, which, instead of possessing a sim-
ple opening, take in their nourishment through many apertures ;
secondly, from those, in which no manifest voluntary motion^
has been hitherto observed, as in several real hydatids. Phy-
siologists have gone further, and have declared certain organ-
ized bodies, in which neither of the above-mentioned charac-
ters, neither a mouth nor voluntary motion, could be discover-
ed, to be animals. Such, for example, are the dropsical blad-
ders occasionally found in the abdomen of persons who have
laboured under ascites, (rarely in any animal except man,)
in vast numbers, and of various sizes, from that of a goose's

80 ON THE CESOPHAGUS AND STOMACH.

egg, to the head of the smallest needle. I have examined a
great number of these, which were found in a dropsical old
man, whose disease and dissolution are related by Richter, in
Loder's Surgical Journal, vol. iii. p. 415. These differ in
their whole structure, and particularly in the formation of their
membranes, much more from the true hydatids than from some
simple morbid watery cysts, which are met with not unfrequently
in warm-blooded animals, and consist so indisputably of a mere
unnatural formation of vessels and membranes, that no person
could think of ascribing to them an independent animal exist-
ence. I have now before me similar cysts from a hen, the lar-
gest of which (about the size of a small hen's egg), like those
of the above-mentioned patient, were quite unattached ; the
rest appeared, on the first examination, from their connexion
with the ovarium, to be nothing else but calices, containing
from a morbid cause, lymph instead of yolk.

I have, however, lately dissected a simia cynomolgus,
whose lungs, liver, and omentum were beset with an abundance
of watery cysts of various sizes. The fluid of these cysts con-
tained an innumerable quantity of microscopical bodies, which
were found, by the employment of strong magnifying powers,
to be hydatids, with a well-formed circle of hooks and mouth»
and consequently must be considered as true independent ani-
mals.

MAMMALIA.

§ 84. We have already shewn, in the second chapter, the
most important circumstances relating to the mouth. Many
species of the genus simia, as well as the hamster, {marmota
cricetus) and some similar species of the marmot, are provided
with cheeJc-pouches, in which the former, who live on trees,
place small quantities of food as a reiServe : the latter employ
these bags to convey their winter provision to their bur-
rows.*

* An accurate description and delineation of these bags may be found in Sulzer's
Versuch der Naturgeschichte des Hamsters, pp. 41, 58, tab. 3, fig. 1: one of the
most masterly zoological and zootomical monographs that has ever been published.

ON THE OESOPHAGUS AND STOMACH. 81

A clieek -pouch exists also in the omilhorhynchus paradoxus. Phil.
Trans. 1800, part 1, tab. 2, fig. 2.

The salivary glands of the mammalia exhibit very few variations in
structure. They are small in the Carnivora, as mastication, properly
so called, can hardly be said to take place in them. On the contrary,
the ruminantia and solipeda have them very large. The size of the
sub-maxillary gland, in particular, is remarkable in the cow and
sheep : it extends along the side of the larynx, quite to the back of
the pharynx.

The parotid and sublingual glands do not exist in the amphibiovs
mammalia, as the seal : the teeth of that animal are only adapted for
seizing their prey, and must be utterly incapable of mastication. The
same remark may be made on the cetacea, where the salivary system
seems to be altogether deficient.

The mucous glands, which constitute the labiales and bvccales of
man, are larger and more distinct in some animals. There is a row
of these opposite to the molar teeth of the dog and cat, penetrating the
membrane of the mouth by several small openings. There is also a
considerable gland in the dog, under the zygoma, and covered by the
masseter. Its duct, equal in size to that of the parotid, or sub max-
illary glands, opens at the posterior extremity of the alveolar margin
of the upper jaw. The molar glands and their openings are very
conspicuous in the pig. The cow and sheep have an assemblage of
similar glands in the zygomatic fossa : their excretory ducts open be-
hind the last superior molar tooth.

§ 85. The peculiar glandular and moveable bag, (bursa fan-
ciumj which is placed behind the palate, has hitherto been
only observed in the camels of the old world : and it pro-
bably serves to lubricate the throat of these animals in their
abode in the dry sandy desarts which they inhabit.*

No mammalia possess an uvula, except ?nan and the simice. As the
cetacea possess no nostrils, they have not of course any velum pa-
lati.

The parts about the pharynx in the cetacea exhibit a very singular
structure. The larynx is elongated, so as to form a pyramidal pro-
jection, on the apex of which its opening is found. The pro-
jection of this part will divide the pharynx ; and the food must
pass on either side of the pyramid. A muscular canal extends from
the pharynx to the blowing holes, and is attached to the margin of
those apertures. The circular fibres of this tube form a sphincter
muscle ; which, by contracting round the pyramid, cuts off the com-
munication between the blowing holes and the mouth and pharynx.

* See Home's Life of J. Hunter, prefixed to the posthiimous work of the latter,
on the blood, iiiflammntion, &c, p. 41.

8^ ON THE (ESOPHAGUS AND STOMACH.

I 86. The oesophagus of quadrupeds is distinguished from
that of the human subject by possessing two I'ows of mus-
cular fibres, which pursue a spiral course and decussate each
other. In those carnivorous animals which swallow voraci-
ously, as the wolf, it is very large ; on the contrary, in many
of the larger herhivora, and particularly in such as ruminate,
its coats are proportionally stronger.*

The opening of the oesophagus into the stomach is marked
by some differences, both with regard to its size, and to the
mode of termination. We understand, from observing these
points, why some animals, as the dog, vomit very easily, while
others, as the horse, are scarcely susceptible of this process,-!*
except in extremely rare instances.

It seems extraordinary, on the first consideration, that the
ruminating animals, in whom the passage of the food from the
first stomach into the oesophagus is very easy, should not be
excited to vomit without such difficulty.

I possess a hair-ball which was discharged by vomiting from
the stomach of a cow, which laboured under an aiFection of •
the digestive powers. The substance in question was dis-
<;harged with violence, after the employment of some white
hellebore placed under the integuments of the breast. J

§ 87. The form, structure, and functions of the stomach,
are subject to great variety in this class of animals.§ In most
carnivorous quadrupeds, || particularly those of a rapacious na-
ture, it bears a considerable resemblance, on the whole, to that
of the human subject ; its form, however, differs in some cases,
as in the seal, (phoca vitulina) where the oesophagus enters

- * Grew may be consulted respecting the oesophagus, as well as the whole ali-
mentary canal of several animals of the different classes. See his Museum Regalis
Societatis.

f See Professor Nebel De Nosologia Brutorum cum Hominum Morbis comparata.
■Giess. 1798.

• X -A. niore detailed account will be found in Voigt's Magazin fur den Neuesten
Zustand der Naturkunde, vol. ii. p. 637,

- § See Neergard's Vergleichende Anatomie der Verdauungswerkzeuge der SoMgetkiere
mud Vögel. Berl. 1806; and SirE. Mome's Lectures on comparative Anatomy.

II H. C. Schroeder De Digestione Animalium Camivororum. Goett. 1755, 4to,

6KN THE CESOPHAGUS AND STOMACH. 83

directly at the left extremity, so that there is no blind sac
formed in the stomach. In some animals, as in the lion, hear,
8cc., it is divided by a slight contraction in its middle, into
two portions. Its coats, particularly the muscvdar one, are
very strong in the Carnivora. We must not, however, trust
implicitly to Roederer, when he says that " the bear has two
stomachs, the first and largest of which is formed like that of
a carnivorous animal, the second and smaller like that of birds
which feed on hard seeds."

The truly carnivorous stomach, as well as the human, which in its
structure is closely allied to it, is according to Sir E. Home, capable
of dividing its cavity into two distinct portions by a transverse con-
traction of its coats, in which state the cardiac portion is, in length,
two thirds of the whole, but, in capacity, much greater, and in se-
veral instances, where the opportunity was afforded of examining the
part immediately after death, the stomach has been found in this form
both in the human body and other animals. This appearance corres-
ponds with the permanent form of the stomach of many other animals.
It is not frequently met with, the fibres of the stomach being readily
relaxed very soon after death by the motion of the liquid commonly
retained in its cavity, and the air which is let loose ; so that such
contraction is only to be expected where opportunities occur of a
very early inspection of the stomach after death. But this appear-
ance in the stomachs of women has been attributed by Soemmering
to the eflPect of the pressure occasioned by the central bone of their
stays.

§ 88. In some herbivora the stomach has an uniform ap-
pearance externally ; but it is divided into two portions inter-
nally, either by a remarkable difference in the two halves of
its internal coat,* as in the horse, or by a valvular elongation
of this membrane, as in several animals of the mouse kind.
This is also the case in the hare and rabbit, where also the
food in the two halves of the stomach differs very much in ap-

• On the whole internal surface of the horse's stomach there are found, in vast
abundance', particularly in spring, the larvaj of two species of oestrus, viz, the
D^ilrm equi (which finnajus called ccsti-us bovis), and the cestnis hermorrlwidaiis, the
true history of which has been elucidated, for the first time in modern days, by that
excellent veterinary surgeon, Mr, Bracy Clark, in the Transactions of the Linnaan So-
ciety, vol. iii. Figures of the oestrus e<iui and its larvas are given in my Ahbildnvfreu
Kdtnrhintm-, Geßeiixtiinili', tab, 47, fig. 3, 4, 5,

84 ON THE OESOPHAGUS AND STOMACH.

pearance, particularly if the animal has been fed about two

hours before death.

In the animals alluded to in this paragraph the left half of the sto-
mach is covered with cuticle, while the other portion has the usual
villous and secreting surface. The cuticular covering forms a more
or less prominent ridge at its termination. The left portion of the
cavity may be regarded as a reservoir, from which the food is trans-
mitted to the true digestive organ ; and the different states in which
the food is found in the two parts of the cavity justify the supposi-
tion. Hence these stomachs form a connecting link between those
of ruminating animals on one side, and such as have the whole sur-
face villous on the other.

The larvae of the cestrus €qui (the large horse-boi) attach themselves
to every part of the stomach, but are in general most numerous about
the pylorus, and are sometimes, but much less frequently, found in
the intestines. They hang, most commonly, in clusters, being fixed
by the small end to the inner membrane of the stomach, where they
adhere by means of two small hooks, or tentacula. When removed
from the stomach they will attach themselves to any loose membrane,
and even to the skin of the hand ; for this purpose they draw back
their hooks almost entirely within the skin, till the two points of these
hooks come close to each other ; they then present them to the mem-
brane, and keeping them parallel till it is pierced through, they ex-
pand them in a lateral direction, and afterwards, by bringing the
points downwards, or towards themselves, they include a sufficient
piece of the membrane with each hook, and thus remain firmly fixed,
for any length of time, without any further exertion of the animal.
They attain their full growth about the latter end of May, and
are coming from the horse from this time to the latter end of June.
On dropping to the ground they soon change to the chrysalis, and in
six or seven weeks the fly appears. This bot is larger and whiter
than that of the oestrus hceiiiorrhoidaHs, which has a reddish cast, but
in its structure, and situation in the animal, resembles the former.
It is found, however, to hang about the rectum previously to quitting
it, which the large horse-bot never does.

Veterinary practitioners do not seem to have decided hitherto,
whether these animals are prejudicial to the horse, nor even whether
they may not be actually beneficial. Their almost universal exist-
ence, at a certain season, even in animals perfectly healthy, shews
that they produce no marked ill effect ; yet the holes which they
leave, where they were attached to the stomach, could hardly be
made without causing some injurious irritation.

For the mode in which these bots get into the stomach, as also for
a most interesting general account of their history and structure, see
Rees's Cyclopaedia, art. Bots, which was furnished by Mr. Clarke,
and from which the preceding account is borrowed.

I 89. In some other mammalia, particularly the herbivorous

ON THE OESOPHAGUS AND STQMACH. 8.5

ones, this organ consists of two or more portions manifestly
distinct externally, and forming as many stomachs. There
are two of these in the hamster* three in the kangaroo^ and
iaja^u,X four in the sloths.^

The carnivorous cetacea have also a complicated stomach,
consisting in some species of three, in others of four, and even
of five subdivisions.il

§ 90. The most complicated and artificial arrangement, both
with respect to structure and mechanism, is found in the well
known four stomachs of the ruminating animals with divided
hoofs ; of this we shall take as examples, the cow and sheep.*^
The first stomach, or paunch, {rumen, penula, magnus ven-
ter, ingluvies ; Fr. le double, Therhier, la panse) is by far the
largest in the adult animal ; not so, however, in the recently
born calf or lamb. It is divided externally into two saccular

* This is excellently described by Sulzer, in his work above quoted,
f Voyage a la Recherche de la Perouse, torn. i. p. 134. Cuvier, Legons d^ Anatomie
com-paree, torn. v. tab. 37 ; and Sir E. Home's Lectures on comparative Anatomy, vol.
i. 4to. p. 155.

i Tyson in the Philos. Trans, vol. xiii. p. 364.

$ Daubenton, vol. xiii. p. 54 and 63 ; and Wiedemann's Archives, vol. i.
II Tyson's Anatomy of a Porpoise. London, 1680, 4to. Hunter in Schnsider's
Beytriigen zur Naturgeschicte der Wallfishlmrten, 1 th. p. 51. Cuvier, Lemons d'Anat.
comp. tab. 38, fig. 2 ; and Home, in the Phil. Trans, for 1807, p. 93.

IT From the multitude of writers who have treated on the stomach of ruminating
animals and its functions, I refer to the following only, on account of the plates
which they have given, particularly such as exhibit the vast increase of size in the
first stomach compared with the fourth, in the early periods of life.
Observ, Anat. Collegii privati Amstelodamensis, pi. 1, p. 12.
Perrault, Essais de Physique, vol. iii. p. 211.
J. C. Peyer, Merycologia. Basil. 1685, 4to.
J. J. Harder! Apiarium, ib. 1687, 4to. p. 16.
Daubenton, torn. iv. tab. 15 — 18.

P. Camper, Lessen over de. thins Zweevende Viestertefte. Leeuward, 1769.
H. Vink, Lessen over de Herkunwing der Runderen, Rotterd. 1770.
J. Burgogne, in the Mem. de I' Acad, de Turin, Sc. Phys. torn. iv. pp. 1 and 309,
1809.

G. Malacarne, in the Memorie di Fis. della Soc, Italiana, tom. xvii. 1815.
Russel's Natural History of Aleppo, vol. ii. p. 425, 1794.

To whicli may be added Sir E. Home's observations on tlie camel's stomach ;
whicli are illustrated by two excellent views of the cow's stomach by Mr. Clift, be-
sides those of the camel. Philos. Trans. 1806, pi. 15, 16.

'gB ON THE CESOPHAGUS AND STOMACH.

appendices at its extremity, and it is slightly separated into
four parts on the inside. Its internal coat is beset with innu-
merable flattened papillae. It is generally in this first stomach,
seldom in the second, that morbid concretions are formed, of
a globular, or elongated, but yet rounded figure. They are
composed of three kinds of substances : viz., of hairs, of the
undigested fibrous parts of plants, or of stony matters.

The hair-balls, particularly in the cow, are formed of the
animal's own hair, which is licked off) and gradually accumu-
lated in the stomach. These either retain a hairy appearance
externally, or they are covered with a dark polished substance,
similar to that which accumulates round their molar teeth.
(See § 24.)

The balls of the chamois, (cegagropilce) consisting of vege-
table matters, particularly of the macerated fibres of the csthu-
sa meum, are found in the animals from which they derive
their name, and are generally of a fine spongy texture, covered
externally with a smooth black coat.

Of the stony concretions which constitute the be%oars, the
oriental ones are derived from the wild goats ; the western
come from the South American species of camel. The latter
are of a yellow-grey colour ; the former of a greenish-black,
with concentrical strata, and generally containing for a nucleus
a small bit of rice-straw.

In a large oriental bezoar, which I sawed through, the nu-
cleus consists of a red-brown, fine but compact spongy sub-
stance, like that of the vegetable balls.

The second stomach, Jioneycomh bag, bonnet, or Icing' s-Jiood,
(reticulum arsineum, ollula ; Fr. le bonnet, le reseau) may be
regarded as a globular appendage of the paunch ; and is dis-
tinguished from the latter part by the elegant arrangement of
its internal coat, which forms polygonal and acute-angled cells,
or superficial cavities.

The third stomach, which is the smallest, is called the ma-
nyplus, which is a corruption of manyplies {echinus, conclave^
centipellio, omasum; Fr.le feuillet, le pseautier); it is distin-
guished from the two former, both by its form, which has been
compared to that of a hedge-hog when rolled up, and by its

ON THE (ESOPHAGUS AND STOMACH. 87

internal structure. Its cavity is much contracted by numerous
and broad duplicatures of the internal coat, which lie length-
wise, vary in breadth in a regular alternate order, and amount
to about forty in the sheep, and one hundred in the cow.

The fourth, or the red, {abomasum, faliscus, ventriculus in-
testinalis ; Fr. la caillette) is next in size to the paunch, of an
elongated pyriform shape, with an internal villous coat like
that of the human stomach, with large longitudinal folds.

§91. The three first stomachs are connected with each
other, and with a groove-like continuation of the oesophagus,
in a very remarkable way. The latter tube enters just where
the three first stomachs approach each other ; it is then con-
tinued with the groove, which ends in the third stomach.
This groove is therefore open to the first stomachs, which lie
to its right and left. But the thick prominent lips, which
form the margin of the groove, admit of being drawn together
so as to form a complete canal, which then constitutes a direct
continuation of the oesophagus into the third stomach.

§ 92. The functions of this very singular part will vary,
according as we consider it in the state of a groove, or of ä
closed canal. In the first case, the grass, &c. is passed, after a
very slight degree of mastication, into the paunch, as into a
reservoir. Thence it goes in small portions into the second
stomach, from which, after a further maceration, it is pro-
pelled, by a kind of antiperistaltic motion, into the oesopha-
gus, and thus returns into the mouth. It is here ruminated,
and again swallowed, when the groove is shut, and the morsel
of food, after this second mastication, is thereby conducted
directly into the third stomach.* During the short time
which it probably stays in this situation between the folds of
the internal coat, it is still further prepared for digestion,
which process is completed in the fourth, or true digestive
stomach.

The process of rumination supposes a power of voluntary

* These fads were understood by Severino, who says, in his instructive Zootemia
Democritea, " A penuia et ollula media revomitur ad os, hinc ruminatum ad con-
clave descendit, et hinc pogtremo ad ventriculuin proprie dictum."

38 ON THE CESOPHAGUS AND STOMACH.

motion in the oesophagus ; and indeed the influence of the
will throughout the whole process is incontestable. It is not
confined to any particular time, since the animal can delay it
according to circumstances, when the paunch is quite full. It
has been expressly stated of some men who have had the
power of ruminating, (instances of which are not very rare,)
that it was quite voluntary with them. I have known four
men who ruminated their vegetable food : they assured me
that they had a real enjoyment in doing this, which has also
been observed of others : and two of them had the power of
doing or abstaining from it at their pleasure. I have already,
on another occasion, observed that the final purpose of rumi-
nation, as applicable to all the animals in which it takes place,
and the chief utility of this wonderfully complicated function
in the animal economy, are still completely unknown ; what
has been already suggested on these points is quite unsatis-
factory.

Fabricius ab Aquapendente has sufficiently refuted the
visionary notion of Aristotle and Galen, namely, that rumination
supplies the place of incisor teeth, the materials of which are
applied, in these animals, to the formation of horns. Perrault
and others supposed that it contributed to the security of
these animals, which are at once voracious and timid, by shew-
ing the necessity of their remaining long employed in chewing
in an open pasture. But the Indian buffalo ruminates, al-
though it does not fly even from a lion, but rather attacks, and
often vanquishes that animal; and the wild goat dwells in
Alpine countries, which are inaccessible to beasts of prey.

The food of carnivorous animals approaching in its constituent
elements more nearly to those of the animal than that of the herbi-
vorous tribes, is more easily reduced into the state which is required
for the nourishment of the body in the former than in the latter case.
Hence arises a leading distinction between the stomachs of these
classes. In the latter animals, the oesophagus opens considerably to
the right of the great extremity, so as to leave a large cul de sac on
the left side of the stomach ; and the small intestine commences near
the cardia, leaving a similar blind bag on the right. The food must
be detained for a long time in such a stomach, as the passage from
the oesophagus to the pylorus is indirect and highly unfavourable to
gpeedy transmission. Animals of thß mouse kind and the rodentia

ON THE OESOPHAGUS AND STOMACH. 89

shew this structure very well ; it is very remarkable in the mus quer-
cinus, (Cuvier, Lemons d' Anatomie coniparee, torn. v. pi. 36, fig. 11).
In the Carnivora, the stomach, which is of a cylindrical form, has no
cul de sac ; the oesophagus opens at its anterior extremity, and the
intestine commences from the posterior ; so that every thing favours
a quick passage of the food. Animals of the weasel kind, which are
strictly carnivorous, exhibit this structure the most completely. The
seal and the lion also exemplify it. (Cuvier, pi. 36, fig. 7.)

§ 93. There are still two peculiarities in the stomachs of
some mammalia, which must be mentioned here, before we
proceed to consider that of birds.

In the opossum, the two openings of the stomach are placed
as near, or even nearer together than in many birds, contrary
to the usual rule in this class of animals.

There is a peculiar glandular body at the upper orifice of
the heavers stomach, about the size of a shilling, full of cavi-
ties that secrete mucus. It resembles, on the whole, the
bulbus glandtilosus of birds, and assists in the digestion and
animalization of the dry food which this curious animal takes,
consisting chiefly of the bark and chips of trees, &c.

The stomach of the pangolin (rnanis pentadactyla) is almost
as thick and muscular as that of the gallinaceous fowls, and
contains, like that of granivorous birds, small stones and gra-
vel, which are probably swallowed, for the same purpose, as
in the case of those birds : that is to say, they are not swal-
lowed, as Burt* supposed, to afford nourishment; but in
order to kill and bruise the insects, &c. which form the ordi-
nary food of the animal, and which might otherwise, by means
of their vitality, resist the chemical action of the gastric juice ;
as the intestinal worms and water-newts, which have been
swallowed, do in man and other mammalia.

According to Cuvier, there is a gland, as large as the head of a
man, situated between the coats of the stomach in the nianati {tri-
chec/ius manatvs borealis). It is placed near the oesophagus, and dis-
charges, on pressure, a fluid like that of the pancreas by numerous
small openings.

Lemons d'Anat. comp. torn. iii. p. 401.

Sir E. Home is of opinion that a glandular structure exists in the

* Aiiatic Retearches, vol. ii.

90 ON THE (ESOPHAGUS AND STOMACH.

stomacli of the sea-otter near the pylorus ; Philos. Trans. 1796^ pi. 2 ;
and Mr. Macartney has discovered an arrangement of glandular bo-
dies in the dormouse, round the oesophagus just before its termination,
similar in situation and appearance to the gastric glands of birds.

The stomach of the ornilhorhynchus hystrix is covered w^ith cuticle,
and possesses sharp, horny papillae near the pylorus. The animal
swallows sand, which may probably assist in the reduction of the
ipod., as, the gravel does which is swallowed by the gallinaceous
birds. Sir E. Home, in the Phil. Trans. 1802, p. 2.

The peculiar structure of the stomachs of the kangaroo, camel, and
lama, which is scarcely noticed in the text, deserves a detailed exa-
mination. The stomach of the kangaroo differs in many particulars
from that of any other known animal, and bears a greater resem-
blance to the human ccecum and colon than to any stomach. The
oesophagus enters the stomach very near its left extremity, which,
unlike the corresponding part in other animals, is very small and
bifid. From the entrance of the Oesophagus the cavity extends to-
wards the right side of the body, then passes upwards, makes a turn
upon itself, crosses over to the left side before the oesophagus, and
again crosses the abdomen towards the right, making a complete
circle round the portion into which the oesophagus enters, and termi-
nates by a contracted orifice at the pylorus.

Its cavity gradually enlarges from the left extremity through its
whole course, till it approaches the pylorus ; it then contracts and dilates
again into a rounded cavity with two lateral processes : beyond this
is the pylorus, the orifice of which is very small. On the anterior
and posterior side of the stomach there is a longitudinal band, similar
to those of the human colon, beginning faintly at the left termination,
and extending as far as the enlargement near the pylorus ; these
bands being shorter than the coats of the stomach, the latter are
consequently puckered, forming sacculi, as in the human colon.

When the cavity of the stomach is laid open, the cuticular lining
of the oesophagus is found to be continued over the portion imme-*
diately below it, and extends to the termination of the smallest pro-
cess at the left extremity, and nearly to the same distance in the
opposite direction ; the cuticular covering is very thin, and extremely
smooth.

The lining of the larger process at the left extremity is thick and
glandular, and in the living body probably receives no part of the
food, but is to be considered as a glandular appendage.

On the right of the oesophagus the cuticle does not end by a trans«
verse line, but terminates first upon the middle of the great curva-
ture, where a villous surface begins by a point, and gradually
increases in breadth till it extends all round the cavity ; its origin,
therefore, is in the form of an acute angle. The villous surface is
continued over the remaining cavity as far as the longitudinal bands
extend ; and that half of it next the pylorus has three rows of clusters
of glands : one row is situated along the great curvature, and con-
sists of fifteen in number ; the other two rows are close to the two

ON THE CESOPHAGUS AND STOMACH. 91

longitudinal bands, and consist only of nine. Besides these there
are two large clusters of an oblong form, situated transversely, where
the longitudinal bands terminate. The internal surface of the rounded
cavity next the pylorus has a different structure, putting on a tesse-
lated appearance, formed by a corrugated state of the membrane.
Immediately beyond the pylorus is a ring of a glandular structure
surroimding the inner surface of the duodenum.

The stomach of the kangaroo, in the peculiarities of its structure,
forms an intermediate link between the stomachs of animals which
occasionally ruminate ; those which have a cuticular reservoir ; and
those with processes or pouches at their cardiac extremity, the inter-
nal membrane of which is more or less glandular. The kangaroo is
found to ruminate when fed on hard food. This was observed by
Sir Joseph Banks, who had several of these animals in his possession,
and frequently amused himself in observing their habits. It is not,
however, their constant practice, since those kept in Exeter Change
have not been detected in that act. This occasional rumination con-
nects the kangaroo with the ruminant. The stomach having a
portion of its surface covered by cuticle, renders it similar to those
with cuticular reservoirs; and the small process from the cardia
gives it the third distinctive character ; indeed it is so small, that it
would appear as if it were placed there for no other purpose.

The kangaroo's stomach is occasionally divided into a greater
number of portions than any other, since every part of it, like a por-
tion of intestine, can be contracted separately ; and when its length
and the thinness of its coats are considered, this action becomes
necessary to propel the food from one extremity to the other.

Such a structure of stomach makes regurgitation of its contents
into the mouth very easily performed. The food in the stomach
goes through several preparatory processes ; it is macerated in the
cuticular portions ; it has the secretion from the pouch in the cardia
mixed with it, and is occasionally ruminated. Thus prepared, it is
acted on by the secretion of the gastric glands, which probably are
those met with in clusters in the course of the longitudinal bands,
and afterwards converted by the secretions near the pylorus into
chyle. —See Sir E. Home's Lectures on co?nparative Anatomy, vol. i.
p. 155, 4to. edit, to which work we are also indebted for the follow-
ing excellent account of the structure of the stomach of the cameL
The structure of this part in the lama, according to the account
which Cuvier has given of it in the examination of a foetus, {Le<^ons
d'Anat. comparee, tom. iii. p. 397,) does not differ essentially from
that of the camel.

Opportunities of examining the camel rarely occur in this coun-
try. One of these, however, was met with thirty years ago, and the
late Mr. Hunter availed himself of it, and made several preparations
to illustrate the different parts of its structure, which are now in the
collection at the College of Surgeons. As the stomach was blown
up, and preserved in a dry state, many peculiarities were left unex-
amined, particularly those respecting the power which the animal

92 ON THE CESOPHAGUS AND STOMACH.

has of carrying a provision of water as a supply when traversing the
deserts.

Sir E. Home was led by many circumstances to be very desirous
of investigating this subject, and in the year 1805, a favourable op-
portunity presented itself; a camel in a dying state having been pur-
chased by the board of curators of the College of Surgeons, with a
view of illustrating the anatomy of that animal.

As Professor of Comparative Anatomy, Sir E. Home was directed
to examine the peculiarities of the stomach, and to make a report on
that subject.

The camel, the subject of the following observations, was a female,
brought from Arabia, twenty-eight years old, and said to have been
twenty years in England, and twelve years in the possession of the
person from whom the Board of Curators purchased it. Its height
was seven feet from the ground to the tip of the anterior hump.

In December, 1805, when it was purchased by the college, it was
so weak, as hardly to be able to stand : it got up with difficulty, and
almost immediately kneeled down again.

By being kept warm, and well fed, it recovered so as to be able to
walk, but was exceedingly infirm on its feet, and moved with a very
slow pace.

It drank regularly every second day six gallons of water, and
occasionally seven and a half, but refused to drink in the intervening
period. It took the water by large mouthfuls, and slowly, till it had
done. The quantity of food it daily consumed, was one peck of
pats, one of chaff, and one-third of a truss of hay.

In the beginning of February, 1806, it began to shed its coat.
Towards the end of March the wind became extremely cold, and the
animal suffered so much from it, that it lost its strength, refused its
food, and drank only a small quantity of water at a time.

In this state it was thought advisable to put an end to so mise-
rable an existence, and it suggested itself to the committee appointed
for the purposes of this investigation, that if this was done soon after
the animal had drunk a quantity of water, the real state of the sto-
mach might be ascertained.

On the second day of April, by giving the animal hay mixed with
a little salt, it was induced to drink, in the course of two hours, three
gallons of water, not having taken any the three preceding days, or
shewn the least disposition to do so.

Three hours after this, its head was fixed to a beam to prevent
the body from falling to the ground after it was dead ; and in this
situation it was pithed by Mr. Cline, junior, assisted by Mr. Brodie
and Mr. Clift.

This operation was performed with a narrow, double-edged po-
niard passed in between the skull and first vertebra of the neck ; in
this way the medulla oblongata was divided, and the animal imme-
diately deprived of sensibility.

In the common mode of pithing cattle, the medulla spinalis only is
cut through, and the head remains alive, which renders it the most
cruel mode of killing animals that could be devised.

ON THE CESOPIIAGUS AND STOMACH. 93

The animal was kept suspended, that the viscera might remain in
their natural state, and in two hours the cavities of the chest and
abdomen were laid open.

The first stomach was the only part of the contents of the abdo-
men which appeared in view. The smooth portion of the paunch
was on the left side, and on the right towards the chest was a cellular
structure, in which it was evident to the feeling that there was air ;
but no part of the solid food with which the general cavity was dis-
tended. On the lower posterior part, towards the pelvis, there was
another portion made up of cells, larger and more extensive than
that which was anterior. On pressing on this part, a fluctuation of
its contents could be distinctly perceived. A trochar with the canula
was plunged into the most prominent of the cells, and on withdraw-
ing it, there passed through the canula twelve ounces of water of a
yellow colour, but unmixed with any solid matter.

This fact having been ascertained, the first cavity was laid open on
the left side, at a distance from the cellular structure, and the solid
contents were all removed.

While this was doing, some water flowed out of the cells, and some
out of the second cavity, but the greater part was retained.

That in the second cavity was found nearly pure, while the other
was muddy, and of a yellow colour, tinged by the solid contents of
the first cavity.

On examining the cellular structure, no part of the solid food had
entered it, nor was there any in the second cavity ; those cavities
having their orifices so constructed as to prevent the solid food from
entering even when empty.

On measuring the capacities of these different reservoirs in the
dead body, they were as follows : The anterior cells of the first ca-
vity were capable of containing one quart of water when poured into
them. The posterior cells three quarts. One of the largest cells
held two ounces and a half, and the cells of the second cavity four
quarts. This, however, must be considered as much short of what
those cavities can contain in the living animal, since there are large
muscles covering the bottom of the cellular structure, to force out
the water, which must have been contracted immediately after death,
and by that means had diminished the cavities.

By this examination it was proved, in the most satisfactory man-
ner, that the camel, when it drinks, conducts the water in a pure
state, into the second cavity ; that part of it is retained there, and the
rest runs over into the cellular structure of the first, acquiring a yel-
low colour in its course.

This confirms the account given by M. Buffbn, in his examination
of the earners stomach, as well as that of travellers, who state that
when the camel dies in the desert, they open the stomach and take
out the water which is contained in it to quench their thirst.

That the second cavity in the camel contained water had been ge-
nerally asserted, but by what means the water was kept separated
from the food, had never been explained, nor had any other part

m> ON THE CESOPIIAGÜS AND STOMACH.

been discovered by which the common offices of a second cavity
could be performed. On these grounds Mr. Hunter did not give
credit to the assertion, but considered the second cavity of the cnmel
to correspond in its use with that of other ruminants, as appears from
his observations on the subject, stated by Dr. Rüssel in his history of
Aleppo.

The difference of opinion on this subject led Sir Everard to exa-
inine accurately the structure of the stomach of the camel, and of
those ruminants which have horns ; so as to determine, if possible,
the peculiar offices belonging to their different cavities.

The cameVs stomach anteriorly forms one large bag, but when laid
open, this is found to be divided into two compartments, on its poste-
rior part by a strong ridge, which passes down from the right side of
the orifice of the oesophagus, in a longitudinal direction. This ridge
forms one side of a groove that leads to the orifice of the second ca-
vity, and is continued on beyond that part, becoming one boundary
to the cellular structure met within that situation. From this ridge,
eight strong muscular bands go off at right angles, and afterwards
form cvirved lines, till they are insensibly lost in the coats of the sto-
mach. These are at equal distances from each other, and, being in-
tersected in a regular way by transverse muscular septa, form the
cells.

This cellular structure is in the left conapartraent of the first ca-
vity, and there is another of a more superficial kind on the right,
placed in exactly the opposite direction, made up of twenty-one
rows of smaller cells, but entirely unconnected with the great ridge.

On the left side of the termination of the oesophagus, a broad mus-
cular band has its origin from the coats of the first cavity, and passes
down in the form of a fold parallel to the great ridge, till it enters thie
orifice of the second, where it takes another direction. It is continued
along the upper edge of that cavity, and terminates within the orifice
of a small bag, which may be termed the third cavity.

This band on one side, and a great ridge on the other, form a canal
which leads from the oesophagus down to the cellular structure in the
lower part of the first cavity.

The orifice of the second cavity, when this muscle is not in action,
is nearly shut ; it is at right angles to the side of the first. The second
cavity forms a pendulous bag, in which there are twelve rows of cells,
formed by as many strong muscular bands, passing in a transverse
direction, and intersected by weaker muscular bands, so as to form the
orifices of the cells. Above these cells, between them and the muscle
which passes along the upper part of this cavity, is a smooth surface
extending from the orifice of this cavity to the termination in the
third.

From this account it is evident, that the second cavity neither re-
ceives the solid food in the first instance, as in the ruminantia, nor
does the food afterwards pass into the cavity or cellular struc-
ture.

The food first passes into the first compartment of the first cavity,

GN THE OSSOPHAGUS AND STOMACH. 95

and that portion of it which h'es in the recess, immediately below the
entrance of the oesophagus, under which the cells are situated, is kept
moist, and is readily returned into the mouth along the groove form-
ed for that purpose, by the action of the strong muscle, which sur-
rounds this part of the stomach, so that the cellular portion of the
first cavity in the cawe/ performs the same office as the second in the
ruminants with horns.

While the camel is drinking, the action of the muscular band opens
the orifice of the second cavity at the same time that it directs the
water into it; and when the cells ofthat cavity are full, the rest runs
off into the cellular structure of the first cavity immediately below,
and afterwards into the general cavity. It would appear that camels,
when accustomed to go journeys, in which they are kept for an un-
usual number of days without water, acquire the power of dilating
the cells, so as to make them contain a more than ordinary quantity
as a supply for their journey ; at least such is the account given by
those who have been in Egypt.

When the cud has been chewed, it has to pass along the upper part
of the second cavity, before it can reach the third. How this is ef-
fected without its falling into the cellular portion, could not, from any
inspection of dried specimens, be ascertained ; but when the recent
stomach is accurately examined, the mode in which this is managed
becomes very obvious.

At the time that the cud is to pass from the mouth, the muscular
band contracts with so much force, that it not only opens the orifice
of the second cavity, but acting on the mouth of the third, brings it
forward into the second, by which means the muscular ridges that
separate the rows of cells are brought close together, so as to exclude
these cavities from the canal through which the cud passes.

It is this beautiful and very curious mechanism which forms the
peculiar character of the stomach of the camel, dromedary, and lama,
fitting them to live in the sandy desarts, where the supplies of water
are very precarious.

The first and second cavities of the camel, as well as those of the
ruminantia, are lined with a cuticle.

The third cavity in the camel is so small, that were it not for the
distinctness of its orifices, it might be overlooked. It is nearly sphe-
rical, four inches in diameter, is not like the third of the ruminantia,
lined with a cuticle, nor has it any septa projecting into it. The cu-
ticle, continued from the second cavity, terminates immediately within
the orifice of the third, the surface of which has a faint appearance af
honey-combed structure ; but this is so slight as to require a close in-
spection to ascertain it.

This cavity can answer no other purpose in the occonomy of the
animal, than that of retarding the progress of the food, and making it
pass by small portions into the fourth cavity ; so that the process,
whatever it is, which the food undergoes in the third cavity of other
ruminants, would appear to be wanting in the caniel, and consequently
not required.

86 ON THE CESOPHAGUS AND STOMACH.

The fourth cavity lies to the right of the first, and has for a great
part of its length the appearance of an intestine ; it then contracts
partially, and the lower portion has a near resemblance in its shape to
the human stomach. Its whole length is four feet four inches ; when
laid open, the internal membrane of the upper portion is thrown into
longitudinal narrow folds, which are continued for about three feet of
its length ; these terminate in a welted appearance ; the ridges are
as large as in the bullock, but not so prominent nor so serpentine in
their course, and for the last nine inches the membrane has a villous
appearance, as in the human stomach. Close to the pylorus there is a
glandular substance of a conical form, which projects into the cavity,
the blunt end of it resting upon the orifice of the pylorus. This is
similar to what is met with in the bullock, but still more conspi-
cuous.

The fourth cavity of the camel corresponds with that of the bul-
lock in all the general characters, and resembles it in most particu-
lars. It exceeds it in length ; but the plicae are so much smaller,
that the extent of the intei^nal surface must be very nearly the same
in both. It differs from it in having a contraction in a transverse di-
rection, immediately below the termination of the plicated part, which
has led both Daubenton and Cuvier to consider these two portions as
separate cavities.

On a comparative view of the stomach of the bullock and camel, \t
appears that in the bullock there are three cavities formed for the pre-
paration of the food, and one for digestion. In the camel, there is one
cavity fitted to answer the purposes of two in the bullock; a. second
employed as a reservoir for water, having nothing to do with tlie
preparation of the food ; a third so small and simple in its structure,
that it is not easy to ascertain its particular office. It cannot be
compared to any of the preparatory cavities of the ruminantia, as all
of them have a cuticular lining, which this has not ; we must there-
fore consider it as a cavity peculiar to ruminants without horns, and
that the fourth is the cavity in which the process of digestion is car-
ried on.

In the stomachs of ruminating animals, the processes which the
food undergoes before it is converted into chyle, are more complex
than in any others. It is cropped from the ground by the fore-teeth,
then passes into the paunch, where it is mixed with the food in that
caxnty ; and it is deserving of remark, that a certain portion is always
retained there ; for although a bullock is frequently kept without food
several days before it is killed, the paunch is always found more than
half full ; and as the motion in that cavity is known to be rotatory,
by the hair bdls found there being all spherical or oval, with the hairs
laid in the same direction, the contents must be intimately mixed to-
gether. The food is also acted upon by the secretions belonging to
the first and second cavities ; for although they are lined with a cu-
ticle, they have secretions peculiar to them. In the second cavity
these appear to be conveyed through the papillae, which in the deer
are conical ; and v^hen examined in a lens, whose focus is half an

ON THE (ESOPHAGUS AND STOMACH. 97

inch, they are found to have three distinct orifices, and that part of
each papilla next the point is semi-transparent. These secretions are
ascertained by Dr. Stevens's experiments to have a solvent power in a
slight degree, since vegetable substances contained in tubes were dis-
solved in the paunch of a sheep.*

The food thus mixed is returned into the mouth, where it is masti-
cated by the grinding teeth ; it is then conveyed into the third ca-
vity, in which a gas is emitted. This was examined by Sir Humphrey
Davy and Mr. William Brande, and was found to be inflammable, and
not to contain carbonic acid, which establishes a difference between
this process and fermentation ; the food is then received into the up-
per portion of the fourth cavity.

The changes which are produced on the food in the three first ca-
vities, are only such as are preparatory to digestion ; and it is in the
fourth ak)ne that that process is carried on. In the plicated portion
the food is acted on by the secretion of the gastric glands ; in that
portion of the fourth cavity of the deers stomach, small orifices are
seen in the internal membrane leading to the cavities, which appear
to be the openings of these glands.

In the lower portion the formation of chyle is completed.

BIRDS.

§ 94. As we have spoken above of the clieelc-pouches of
some mammaha, we must here take notice of the throat sac,
which is found in the male bustard, under the integuments of
the front of the neck, and opens by a wide aperture under the
tongue : its use has not been hitherto discovered.i*

A very remarkable dilatation of the fauces occurs in the pelican.
An immense pouch, capable of holding several quarts of water, lies
between the branches of the lower mandible, and constitutes a reser-
voir for the food, which consists of fishes. By means also of this
bag, the animal feeds its young until they are of sufficient strength
to provide for themselves.

§ 95. The oesophagus, which generally descends on the
right of the trachea, as well as its opening into the stomach,
is of immense size in many carnivorous birds ; considerably
larger indeed than the intestinal canal. The capaciousness of

• Dissertatio Physiologica inauguralis de Alimentonim concoctione, Auctore Edwardo
Stevens. Edinb. 1777.

t Edwards'» Natural History of Birda, torn. ii. tal}. 73 ; and Schneider, Comment.
ad reliqun LUrrnrum, Freder. 2ridi, torn. ii. p. 0.

H

98 ON THE CESOPHAGUS AND STOMACH.

this tube (enables it to hold for a time the entire fish, and
large bones which these birds swallow, and which öannot be
contained in the stomach ; and facilitates the discharge, by
vomiting, of the indigestible remains of the food, which form
balls of hair, feathers, and bony matter. A sea-gull, which I
kept alive for some years, could swallow bones of three or four
inches in length, so that the lower end only reached the sto-
mach, and was digested, whilst the rest projected into the
cesophagus, and descended gradually, in proportion as the
former was dissolved.*

Proper salivary glands, such as secrete that clear and limpid fluid
constituting the saliva, do not exist in birds. For mastication, or
the comminution of the food, and its reduction into a soft paste, to
which function these glands are entirely subservient, is not performed
in the mouth of these animals, but in their gizzard. Birds, how-
ever, have a very copious apparatus of those mucous follicles, which
form the glandules labiales, buccales, linguales, &c. of the human sub-
ject. The sides of the tongue, the under surface of that organ, and
the entrance of the oesophagus, are beset with numerous openings of
these glands, which furnish an abundant supply of viscid mucus to
defend the tender lining of these parts from the hard bodies which
constitute the food of several birds. These apertures are very con-r
spicuous in the gallinse. The ostrich, in particular, has two flattened
bodies at the upper and back part of the palate, which may be com-
pared in some respects to tonsils. The surface of these is covered
with innumerable foramina, from which a tenacious mucus may be
expressed. The soft palate is entirely deficient in birds : the nostrils
open on the bony palate by longitudinal slits, the sides of which
are guarded by soft pointed papillse.

§ 96. The oesophagus expands just before the sternum into
the crop, {ingluvies, prolobus ; Fr. le jabot) which is furnished
with numerous mucous, or salivary glands, disposed in many
cases in regular rows. In such birds as nourish their young
from the crop, the glands swell t remarkably at that time, and
secrete a greater quantity of fluid.J This takes place in an
inverse ratio to the age of the young pigeon, as long as the

* See Morton's Natural History of Northamptonshire, p. 353 ; and Dr. Persfion,
in Yoigt's Neuen Magasin, vol. i. p. 56.

t Hunter on the Animal Economy, p. 193 ; and Neergaard, tab. S, %..2 and 3.
I See Viridet du bon Chyle, pour la Proditction du Sang, torn. i. p. 78.

ON THE CESOPÖAGUS AND STOMACH. 99

old birds keep their food in the crop. This part is found in
land birds only, but not in all of these ; it exists in all the
gallince, and in some birds of prey.*

The crop of the cotnmon fowl, and of the other galUnce, is of a
globular form, and placed just in front of the chest. The oesophagus,
which opens at its upper part, commences again about the middle of
the bag, so that the crop itself forms a md de sac, or bag, out of the
regular course of communication between the two openings of the
oesophagus. In the pigeon there is a spherical bag formed on both
sides of the oesophagus, which tube itself is very large in the pouting
pigeon, and admits of being distended with air, so as to cause the
appearance from which the name of the bird is derived. In the
birds which we have now mentioned, the crop must be considered
as an organ for macerating the dry and hard vegetable substances
which constitute the food of these animals. The accipitres also have
this dilatation ; but it must be regarded in them merely as a reservoir
for the food which does not require any previous softening. It is
wanting in the piscivorous birds ; but its place is supplied by the
great size of the oesophagus, in which entire fishes are held until they
can pass into the stomach. The heron, cormorant, &c. are examples
of this peculiarity.

§ 97. There is another glandular and secretory organ, much
more common than the crop, belonging indeed very generally,
though it is wanting in some birds, as the kings-ßsher, to the
whole class ; this is the bulbus glandulosus, {echinus, infundi-
bulum, proventriculus, corpus tubulosum) which is situated
before the entrance of the oesophagus into the proper sto-
mach, and whose form and structure vary considerably in the
different genera and species. In the ostrich, for example, its
magnitude and form give it the appearance of a second sto-
mach.-)- In some other birds, as the psittaci, ardece, {crane^
stork, &c.) its appearance is different in form from that of the
proper stomach, and its size is larger ; while, on the contrary,
in gallinaceous birds, it is much smaller.^

* See Wolf, in Voigt's Magazine, vol. i. p. 72.

t Hence, Valisnieri calls it in this animal, the first stomach ; see his Notomia dello
Strutzo, 1713, p. 159 ; and Cuvier's Anat. comparee, tab. 40, fig. 3.

i For an account of several other variations in the structure of this part, in dif-
ferent birds, see the Parisian M^moires pour sermr a VHislnire Naturelle den Ani-

100 ON THE CESOPHAGUS AND STOMACH.

The term bulbus glandulqsus {ventricule succenttirie, Cuvier) is ap-
plied to a small portion of the oesophagus, just before its termination
in the stomach. This part is obviously rather larger and thicker in
its coats than the rest of the tube. Its structure may be most clearly
discerned in the gallinaceous genera. The oesophagus consists, as
in other parts, of its two coats, the muscular and villous ; but a vast
number of glandular bodies, cylindrical in form, and arranged in
close apposition to each other, are interposed between these tunics,
and entirely surround the tube, constituting the " zone of gastric-
glands" of Mr. Macartney, (Rees's Cyclopedia, Art. Birds). These
bodies are hollow internally, and open into the cavity of the bul-
bus. The fluid secreted by them, which, from their number and
size, must be furnished in great abundance, passes into the gizzard,
and mixes with the food in proportion as it is triturated by that
organ. These glands are much less distinct in those birds which
live on animal food, as the accipitres and the piscivorous genera ; but
they exist universally, and their openings can always be discerned.
The ostrich affords an opportunity of examining them to great advan-
tage. In the African species the oesophagus is dilated into an im-
mense bag, capable of holding several pints of water, and is five or
six times larger than the gizzard itself, which is placed on the right
and anterior part of this dilatation. The glands do not surround the
tube, so that the term zone would be here inapplicable. They
form a long but narrow band, commencing at the termination of the
oesophagus, and running along the front of the bag towards the giz-
zard. This band measures about twelve inches in length, and not
more than three at its greatest breadth. The size of the individual
glands varies: they are largest in the middle, and decrease towards
either margin of the band. Some of them equal a large pea, and
their openings are of a proportional size. They are arranged in close
apposition to each other, and the inner surface of the pouch is covered
by a continuation of the insensible lining of the gizzard, which sepa-
rates very easily from the surface.

The solvent glands in birds are larger, and more distinct from the
other parts of the digestive organs than in the mammalia. The solvent
glands in the whole of the extensive genus/a/co of Linnaeus are cy-
lindrical bodies, with very small canals, a villous internal surface, and
thick coats, open at one end, closed and rounded off at the other ;
they are placed on the outside of the membrane which lines the
cardiac cavity, they lie parallel to one another, and nearly at right
angles to the membrane through which they open, the closed end
being slightly turned upwards, so as to make the orifice the most de-
pending part. In the golden eagle (the falco chrysaetos, L.) and the
sea eagle, (falco ossifragus) they form altogether a broad compact
belt ; but in the haivk (fatco nisus) this belt is slightly divided into
four distinct portions ; immediately below these glands the cavity
becomes wider, and is inclosed in a digastric muscle of weak power,
with a flat tendon on each side The infernal surface of this cavity^
which is the gizzard, is soft and vascular.

ON THE OESOPHAGUS AND STOMACH. 101

In all animals that live on animal food the solvent glands appear
to have a similar structure to that which has been just described,
only differing in size and situation. In the solan goose (pelecanus
hassanus) these glands are rather larger than in the eagle, but are
placed in the dilated part of the cavity of the gizzard, forming a
complete belt of great breadth, consequently are extremely nu-
merous.

In the heron [ardea cinerea) they are in the same situation as in the
solan goose; they are thinly scattered, and do not form a complete
belt, being more numerous on the anterior and posterior surfaces. A
ball offish-bones, held together by mucus, was found in the cavity of
the gizzard.

In the cormorant (^pelecanus carbo) the situation of the solvent
glands is the same as in the solan goose ; but they only form two
circular spots, one anterior, the other posterior.

In all these birds the inner membrane of the gizzard is soft and
smooth, but that portion which covers the solvent glands has a more
spongy or villous appearance ; and this part secretes a mucus which
the other parts do not. This fact appears to be ascertained by the
following circumstances : on examining the gizzard of a cormorant
that died in consequence of an inflammation in the oesophagus, which
had been communicated to the internal membrane of the gizzard, a
viscid mucus was found upon the surface covering the solvent glands,
and this was not met with in any other part ; so that the mucus had
been evidently secreted there, and was afterwards coagulated by the
liquor of the solvent glands poured upon it, coagulation being the
first process wliich takes place in the act of digestion. This ex-i
plains the circumstance of ascarides being frequently found enve-
loped in mucus in this part of the cormorant's gizzard, the mucus on
which they feed being secreted in consequence of the irritation they
produce on the membrane. In the same manner the flakes in the bi-
liary ducts of the sheep increase the secretion of the bile by ir-
ritating these canals, and then feed on it.

In birds that live upon fish and sea insects with crustaneous
coverings, as the sea-gull, (larus canus) the gizzard has a horny cu-
ticular lining, and the solvent glands are in the same situation as in
the genus falco.

In those birds that live on land insects, some of whose coverings
are soft, others hard, there is a diflerence in the structure of the di-
gestive organs from what has been described. The solvent glands
are placed in a triangular form in the cardiac cavity, and immediately
under it is a small gizzard with a horny lining. Of this kind is the
ivood-pecker (picus minor).

There is still another variety in the structure of these organs. In
the little auk (the ulea alle) the solvent glands are spread over a
greater 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 appears to be a direct continuation of the oesophagus,
distinguished from it by the termination of the cuticular lining, and

102 ON THE CESOPHAGUS AND STOMACH.

the appearance of the solvent glands. The cavity is continued down
with very gradual enlargement below the liver, and is then bent up
to the right side, and terminates in a gizzard ; when the cavity ia
laid open, the solvent glands are seen at its upper part, every where
surrounding it, but lower down they lie principally upon the poste-
rior surface, and where it is bent upwards, towards the right side,
they are entirely wanting. The gizzard has a portion of its anterior
and posterior surfaces opposite each other, covered with a horny cu-
ticle.

In birds that live principally on vegetable food, the solvent
■ glands have a different structure, according to the substances the
birds are intended to feed upon, and vary in situation according to
the habits of life.

In the pigeon (columba domestica) their situation is the same as in
the genus falco, but their size is small, the external orifices large,
and the coats thin, so that they resemble the glands in the English
heron, having however larger cavities.

In the sivan (anas cygnus) the solvent glands appear to be cylinders,
as in the genus falco, but are not straight, bending upon one another
in a direction obhquely upwards ; their internal surface is not villous,
but rather broken and irregular.

In the goose [anas anser) they have the same situation, but when
laid open, the sides are found to be cellular.

In the common fotvl (phasianus gallus) these glands are made up
of four small short processes uniting in a middle tube, which opens
externally by one orifice.

In the turkey {pieleagris gallopavo) they consist of four small pror
cesses, which diverge from each other in opposite directions.

In many large birds that only walk and run, their wings being too
small to enable them to fly, the digestive organs are formed in many
respects differently from those of other birds.

In the cassowary (cassuarius emu) the solvent glands are situated
between the crop and gizzard, as in many other birds, but this part
is dilated into a large cavity, and separated from the gizzard by an
oblique muscular valve ; in this cavity the food may be retained for
some time, but cannot be triturated there, since the stones and other
hard bodies swallowed will readily force a passage into the gizzard.

In the American ostrich {rhea Americana) the solvent glands are
fewer in number than in other birds. They only occupy a small
portion of a circular form on the posterior side of the cardiac cavity ;
this however is compensated by the complex structure of which they
are composed. To each gland there is one common orifice ; when
the cavity to which it leads is laid open, three smaller orifices are ex-
posed, each of which communicates with five or six processes like
the fingers of a glove. The structure is similar to that of the solvent
glands of the heaver among quadrupeds. The cardiac cavity in
which the glands are situated is dilated to a large size, as in the cas-
sowary, and there is a similar muscular valve, separating it from the
gizzard. The digastric muscle is weak, but the fibres of which it is

ON THE (ESOPHAGUS AND STOMACH, 103

composed, and tendons between the two bellies of the muscle, are
beautifully distinct.

. In the African ostrich (struthio camelus) the isolvent glands are un-
usually numerous ; the space in which they are situated is not only
dilated into a cavity, but is continued down below the liver, and
then bent up upon itself towards the right side, where it terminates
in a strong gizzard nearly at the same height as the beginning of the
cardiac cavity. The gizzard is unusually small, the grinding sur-
faces do not admit of being separated to a great distance from one
another ; and on one side there are two grooves, and two corres-
ponding ridges on the other. Beyond the cavity of the gizzard is an
oval aperture, with six ridges, covered with cuticle, to prevent any
thing passing out of the gizzard till it is reduced to a small form.
The cardiac cavity of one of these birds was found to contain stones
of various sizes, pieces of iron, and halfpence ; but, between the
grinding surfaces of the gizzard, there were only broken glass-beads,
of different colours, and hard gravel mixed with the food. The
cassowary and American ostrich differ from birds that fly, in having
the solvent glands placed in a cavity of unusual size, and the muscu-
lar structure of the gizzard uncommonly weak ; their mode of pro-
gression, which is a kind of run, producing so much agitation be-
tween the stones and the food, as to render a strong muscular action
unnecessary.

In the ardea argala, a native of Bengal, which feeds upon carrion,
and is exceedingly voracious, the solvent glands are differently
formed from those of any other bird ; each gland is made up of five
or six cells, and these open into one common excretory duct. The
glands are disposed in two circular masses, one on the anterior, the
other on the posterior surface of the cardiac cavity, putting on a si-
milar appearance to those of the cormorant, but differing both in
structure and situation. The gizzard is lined with a horny cuticle,
nearly of the same general appearance as that of the crow, and the
digastric muscle is of similar strength.

In the parrot tribes, which feed principally on seeds and fruits,
there is a different formation of the digestive organs. There is a
crop on the right side, as in the fowl, but the cardiac portion is
unusually large, and the gastric glands are spread over a consider-
able portion of its surface, but are wanting at the lower part, and
immediately below there is a regularly formed gizzard of a very di-
minutive size. In this respect the parrot accords very nearly in its
digestive organs to the wood-peckers among those birds that live
upon animal food, having a cavity in which the soft substances may
be acted upon by the gastric liquor, and also a gizzard, in which any
harder substances may be broken down, and by that means rendered
fit to be acted upon by the secretion of the gastric glands.

In examining the gastric glands of the Java swallow Sir E. Home
thought that he saw an obvious difference between the appearance
of the orifices, by which the secretion is forced into the gizzard of
this bird, and that of the common swallow. But Mr. Clift, who saw

104 ON THE (ESOPHAGUS ATSfD STOMACH.

the preparation to which Sir Everard alludes, has assuied the editor
that he could not perceive the difference which Sir Everard mentions,
Sir E. Home concludes, from a comparison of the peculiarities in
the structure of the digestive organs in birds generally, and particu-
larly of the solvent glands, gizzards, and intestines in the cassuarius
emu, a native of Japan, the ihea A>/iericana, a native of South Ame-
rica, and the struthio cumelus of Africa, that the gizzard becomes
more and more fitted to economize the food as the country to which
the bird belongs becomes less fertile, and that the extension of the
lower intestines and cceca warrants us in believing that the processes
carried on in them render the undigested food subservient to the ani-
mal's support. See Phil. Trans. 1813.

§ 98. In most birds, the stomach lies at the upper* part of
the abdomen, that is, close to the spine, and rests in a manner
on a stratum of intestines ; in the cuckoo, however, it lies be-
low. This peculiarity does not belong exclusively to that cu-
rious bird,"!- for I have found it in the ramphastos, and the
corvus caryocatactes {the nut-cracker).

% 99. The structure of the stomach differs most widely in
the different orders and genera of this class. It appears
merely as a thin membranous bag in several of those which
feed on flesh and insects, when compared with the thick, mus-
cular globes of the granivorous genera. But there are both
many intermediate links J between these extremes, and at the
same time considerable analogies in the structures, which are
apparently the most opposite. This is particularly observable
in the course of the muscular fibres, § and in the callous struc-
ture and appearance of the internal coat,|| in which points many
membranous stomachs have a great resemblance to those of
the gallince.

§ 100. Both parts, but particularly the muscular, are very

* See § 41, note.

t Herissant thought this circumstance peculiar to the cuckoo ; and supposed that
it furnished an explanation why that bird does not incubate. Mem. de I'Acad. des Sc.
1755.

:j: Haller has collected a number of these in his Element. Physiohg. torn. vii.
p. 115.

§ Duverney, CEuvres Anatomiques, tom. ii. p. 447.

II Wepfer, Cicutie AquaticcE Historia et Noxce, p. 174. This is, on the whole, a
jjiost instructive work.

ON THE (ESOPHAGUS AND STOMACH. 105

strong in the gizzard (ventriculus bulbosus) of granivorous
birds.* We find here, instead of a muscular coat, four im-
mensely thick and powerful muscles ; viz., a large hemisphe-
rical pair at the sides, {laterales) and two smaller ones {inter-
medii) at the two ends of the cavity ; all the four are distin-
guished, both by the unparalleled firmness of their texturej-f-
and by their peculiar colour, from all the other muscles of the
body.

The internal callous coat must be considered as a true epi-
dermis, since, like that part, it becomes gradually thicker from
pressure and rubbing.:{: It forms folds and depressions to-
wards the cavity of the stomach, and these irregularities are
adapted to each other on the opposed surfaces. The cavity
of this curious stomach is comparatively small and narrow ; its
lower orifice is placed very near the upper. Every part of
the organ is, indeed, calculated for producing very powerful
trituration. The numerous experiments which Reaumur per-
formed, in order to determine the extent of this triturative
power, are universally known. There are two curious ob-
servations on this subject less generally known. Felix Plater
found an onyx, which had been swallowed by a hen, to be
diminished by one-fourth in four days ; and a louis d'or lost
in this way sixteen grains of its weight. § The end and
use of swallowing stones with the food, the well-known in-
stinctive practice of granivorous birds, have been very dif-
ferently explained. Caesalpinus considered it rather as a
medicine than as a common assistance to digestion ; Boer-
haave, as an absorbent for the acid of the stomach ; Redi,
as a substitute for teeth. According to Whytt, it is a me-
chanical irritation, adapted to the callous and insensible na-
ture of the coats of the stomach. Spallanzani rejected all

• J. C. Peyer, Anatome Ventriculi Gallinacei, in his Exercit. de Glandulis Intesti-
nor. Scafhaus. 1677, 8.

t W. G.Muys De Carnis Musculosm Structura. Ltid. 1741, 4to. tab. 1.
I Monro's Essay mi Comparative Anatomy.
$ See Swammerdam, Biblia Natura:, p. 168.

106 ON THE OESOPHAGUS AND STOMACH.

supposition of design or object, and thought that the stones
were swallowed from mere stupidity. I think there is not
much sagacity to be discovered in this opinion, when we con-
sider that these stones are so essential to the due digestion of
the corn, that birds grow lean without them, although they
may be most copiously supplied with food. This paradoxical
opinion has, however, been already refuted by Hunter and
Fordyce.* The use of swallowing these stones seems to me to
consist in this, that they kill the grain, and deprive it of its vi-
tality, which otherwise resists the action of the digestive pow-
ers. Thus it has been found, that if the oats and barley given
to horses, are previously killed by heating, the animal only re-
quires half the quantity, and yet thrives equally.

AMPHIBIA.

§ 101. The capacious oesophagus of the turtle has a very
striking peculiarity in its structure ; its internal coat is beset
with innumerable large, firm, and pointed processes + of a
white colour. Their points are all directed towards the sto-
mach, and they probably serve to prevent the return of the
food, which can only enter the stomach gradually.

§ 102. The oesophagus of the crocodile is of the funnel
shape ; the stomach of the animal resembles, although not very
closely, that of the granivorous birds, in the nearness of its
two apertures and the thickness of its coats.

§ 103. The stomach of serpents can hardly be distinguished
from the oesophagus, except that it is somewhat larger. It is
very short when compared with the great length of that tube.

Reptiles resemble birds in having their nostrils terminated by two
longitudinal slits on the palate, and in the want of the velum palati
and epiglottis.

The oesophagus of the serpent kind is of immense magnitude ; for
these reptiles swallow animals larger than themselves, which are re-
tained for a considerable time in the tube and descend into the sto-

* See J. Hunter's Animal Economy, p. 155 ; and G. Fordyce an Digestion, p. 23.
t Ruysch, Thesaurus Anatomicus, 8vo. tab. 2.

ON THE OESOPHAGUS AND STOMACH. 107

mach by degrees, where they are slowly subjected to the action of
the gastric juice. The whole process sometimes occupies many days,
or even weeks.

FISHES.

§ 104. The oesophagus is short in most fishes; but this
character is not universal, as Aristotle supposed ; * nor is a
long oesophagus peculiar to fishes of an elongated form. The
large stomach of the tetrodon hispidus is particularly worthy
of notice, for the animal can fill it in case of necessity with air,
and change its naturally long form into a spherical one.'f

From the peculiar formation of the nose of fishes, and from their
respiring by means of gills, their fauces have no connexion with any
nasal cavity, or glottis.

The oesophagus is pf great width in fishes, and is distinguished
with difficulty in many cases from the stomach. These animals
swallow their food whole, without subjecting it to any mastication ;
and, if the stomach will not hold the whole, a part remains in the
oesophagus, until that which has descended lower is digested. The
alimentary canal is generally very short ; sometimes extending
straight from the mouth to the anus with very little dilatation, as in
the lamprey {fetromyzon marinus).

§ 105. The size and form of the stomach vary J very consi-
derably in this class. Its coats are thin in most fishes, but in
some they are very thick and muscular,§ and have a callous
internal covering ; still, however, the resemblance between
these and the stomachs of granivorous birds is very remote.

INSECTS.

§ 106. I have already observed, on another occasion, [[ that
the business of nutrition in insects does not seem to have for
its object the mere preservation of the individual, as in most

* See Fabricius ab Aquapendente, p. 101 of the edition quoted above.

♦ S. Geoffrey St. Hilalre, in his Descr. de I'Egypte Hist. Naturelle.

X Representations of the stomach of several fishes may be seen in the 2d vol. of
Collins's System of Anatomy. Lend. 1685 ; and in the M6 moires present^ ä I' Acad, des
Se. by Vicq d'Azyr.

$ Rondelet, p. 70.
In the Handbuch der Natxirgesohichte, (Manual of Natural History) p. 298 ; or
p. 1 72 of Mr. Gore's excellent translation of this work.

108 ON THE CESOPHAGUS AND STOMACH.

red-blooded animals ; but chiefly the consumption of organ-
ized matter ; which will appear clearly, from considering the
structure of their alimentary canal.* In most of those which
are subject to a metamorphosis, the stomach, in the larva state,
is of a great size, in comparison with the short intestinal canal :
while those, on the contrary, which take little or no nourish-
ment in their perfect state, have this organ remarkably dimi-
nished, and as it were contracted.*!^

§ 107. Our limits will allow us to take but little notice here
of the endless varieties and peculiarities of internal structure,
which occur in the different genera and species of this multi-
form class of animals. We shall therefore only bestow two
words on those of the oesophagus and stomach. In several
cases the commencement and termination of the alimentary
canal, the oesophagus, and rectum, are surrounded by an annu-
lar portion of the spinal marrow. J

In the earwig (forficula auricularia) the upper orifice of
the stomach is furnished with two rows of teeth .§

In some of the grylli (grasshoppers) the stomach itself is
small, but the oesophagus much larger.

In some species of that genus, particularly in the gryllus
gryUotalpa, the stomach consists of three or four vesicular

* "RzviiAohT Über die Verdauungswerkzeuge der Insecten. Halle, 181 1.

t Compare, for instance, the stomach of the larva of the papilio urticce with that
of the perfect butterfly, in Swammerdam, BibUa Naturee, tab. 34, fig. 4, and tab.
36, fig. 1 ; and particularly the whole series of changes which takes place in the
pass, hrasdcce, in Herold's Entwickelungsgechichte Geschichte der Schmetterlinge. Marb.
1815, 4, tab. 3, fig. 1-12.

^ There are several delineations of the stomach in the different orders of this class,
viz. that of the scarabcsus nasicornis, in Swammerdam, tab. 27. Of the earth-beetle,
in Rösel, vol. ii. tab. 8. Of the stag-beetle, (lucanus cervus) ibid. tab. 9. Of the
earwig, in C. F. Posselt, Tentamina circa Anatomiam forficulcB auricularicE. Jen.
1800, 4to. fig. 26. Of the gryllus veirucivorus, in Rösel, vol. ii. tab. 9. Of the
silkworm, in Malpighi, De Bombyce, 1669, 4to. ; in Rösel, vol. iii. tab. 9 ; and
Bibiena, in the Comment. Instit. Bonon. tom. v. part 1, tab. 2 and 3. Of the cossus,
in Lyonet's chef d'oeuvre, Anatomie de la Chenille, &c. Of the ephemera horaria,
in Swammerdam, tab. 15. Of the larva of the musca chamceleon, ibid. tab. 41>
Of the musca putris, ibid. tab. 43. Of the louse, ibid. tab. 2.

§ Fosselt, in the work above quoted, p. 27, fig. 27.

ON THE OESOPHAGUS AND STOMACH. 109

portions,* which have been compared with the stomachs of
the ruminating mammaUa.t

We have already (§ 1) mentioned the stomach of the lobster ,
and some other species of the genus cancer :% which is pro-
vided with several portions of bone. It contains also three
teeth, which, together with the stomach itself, are annually re-
produced, at least in the craw-fish {cancer astacus).

The Crustacea, and some insects, are furnished with organs of mas-
tication of similar structure. Their mouth is formed of two or more
pairs of jaws placed laterally. These move from without inwards,
and vice versa, whereas those of red-blooded animals move from
above downwards, and back again. The parts, which are termed the
lips of insects, are two bodies ; of which one is placed above or in
front of the jaws, and the other below or behind them. The palpi or
feelers are articulated to the jaws. All insects, which have jaws, pos-
sess the power of masticating hard animal and vegetable substances ;
for these parts are of a firm horny texture, and in many cases are
very large, when compared with the size of the animal.

The locusts, {grylli) the dragon-fly, {Jibellula) the beetles, and parti-
cularly the lucanus cervus, or stag beetle, and the staphylinus inaxillo-
sus, are examples in which the jaws are very large and manifest, and
often possess denticulated edges. All the genera of the following or-
ders have jaws; viz. the coleoptera, orthoptera, neuroptera, and hyine-
noptera. The insects of the remaining orders derive their nourish-
ment chiefly from liquids ; which they get either from animal or ve-
getable substances by means of a spiral and tubular tongue, or a soft
proboscis, (as in the lepidoptera) with a broad opening, admitting of
extension and retraction, (the hemiptera) or a horny pointed tube,
containing sharp bristly bodies internally (the diptera and aptera).

The stomacli of the bee is a transparent membranous bag, in which
the nectar of the flowers is elaborated and converted into honey.
The animal vomits it up from this reservoir, and deposits it in the
hive.

The stomach of the crab and lobster is a very singular organ. It
is formed on a bony apparatus, in short a species of skeleton ; and
does not therefore collapse when empty. To certain parts of this
bony structure, round the pylorus, the teeth are affixed. Their sub-
stance is extremely hard, and their margin is serrated or denticulated :
as they surround the tube, near the pylorus, nothing can pass that

• Cuvier, in the Mömoires de la Societe d'Hist, Nat. de Paris, an 7, tab. 4.

t Swammcrdam, Algem, Verltandel. van de Bloedeloose Dierkcns. Utrecht,, 1769,
4to. ; and G. H. Velschii, Hecatostea Ohs. Aug. Vind. 1675, 410. p. 71.

X See Rösel, vol. iii. tab. .58 ; anrl Fr. Succon. Myolofrice insectonim Specimen,
ir.idelb. 1813.

IIÖ ON THE CESOPHAGÜS AND STOMACH*

opening, without being perfectly comminuted. These bones and teeth
are moved by peculiar muscles.

VERMES.

§ 108. We can only select a few instances,* as examples of
this class, which includes a great number of creatures, differ-
ing widely from each other.

The aphrodite aculeata, (sea-mouse) which is well-known
on account of its beautiful colours, possesses a very remarka-
ble stomach. The form and size of the viscus resemble those
of a date, while in strength and compactness of texture it ap-
proaches to that of granivorous birds. t

The oesophagus is expanded into a crop in many testacea,
particularly among the bivalves ; and it is covered internally
with numerous small teeth. J

The powerful stomach of the bulla lignaria contains three
hard calcareous shells, by which the animal is enabled to bruise
and masticate the other testacea, on which it feeds.^ This
stomach was lately taken by some naturalists for a peculiar
genus, of an entirely new order of three-shelled testacea.

* The following zootomists have given us representations of the stomach, in the
different orders of vermes, viz. Tyson, of the round worm, (lumbricus teres, ascaris
lumbricoides) in the Phitos, Trans, vol. xiii. No. 147 ; which may be compared with
Werner, Vermium Iiitestin. Expositio. Lips. 1782, tab. 7. Willis, of the earth-
worm, tab. 4; also Vandelli, Diss, de Aponi Thermis, &c. Patav. 1758, 8vo.
Morand, of the leech, in the M^m. de I' Acad, des Sc. an 1739. As well as
Bibiena,. in the Comm. Tnstit, Bonon, torn. vii. p. 102. Johnson on the medicinal
leech. Lond, 1816, p. 124; and Home's Lectures on comparative Anatomy, tab. 70.
Of the slug, Swammerdam, tab. 9. Of the cuttle-fish, ibid. tab. 51. Also Monro,
On tlie Physiology of Fishes, tab. 31. Of the different species of mollusca. Cuvier,
MSnwires sur les Mollusques. Paris, 1817. Leue Dc Pleurobranchaa nono Molluscorum
genere, Hal. 1813. Poli, of several testacea, in his Testacea ut^'iusque Sicilite, viz.
the pholas dactylus, torn. i. tab. 7 ; the tellina planata, tom. i. p. 14. Mactra Nea-
politana, tom. ii. tab. 19 ; the venus chione, tab. 20. Of the snails. Wohnlich De
Heiice pomatia. Wirceb. 1813. Stiebal, Limnei Stagnalis Anatome, Götting. 1815.
Feider De Halyotidum structura. Hal. 1814.

t See Pallas, Miscellanea Zoologica, tab. 7.

I For instance, in the chiton cinereus, see Poli, tom. i. tab. 3. Compare also the
oesophagus of the cuttle-fish, which is furnished with teeth in the same manner. See
Turberville Needhara's Nouvelles Observations Microscopiques, tab. iii.

§ Humphrey in the Trans, of the Linncean Society, vol. ii. p. 15. Draparnaud in
the Journal de Physique, tom. vii. p. 146.

ON THE OESOPHAGUS AND STOMACH. Ill

In most of the proper mollusca, the stomach is of a simple
membranous structure, and of very different comparative mag-
nitudes. I have found it very large in the scyllaa pelagicum.
It occupies the greatest part of the body in the leech, and is
divided internally by means of ten imperfect fleshy partitions,
into somewhat sepai*ate portions.

Lastly the armed polypes Qtydrce) and other similar ssoo-
phytes, can hardly be considered as any thing more than a
mere stomach, having its openings furnished with tentacula.

In those mollusca, which possess jaws, these parts are fixed in the
flesh of the animal, as there is no head to which they can be articu-
lated. They are two in number in the cuttle-fish, are composed of a
horny substance, and resemble exactly the bill of a parrot. They are.
placed in the centre of the lower part of the body, and are surround-
ed by the tentacula, which enable the animal to attach itself to any
objects. By means of these parts, the shell-fish, which are taken for
food are completely triturated. The common snail and slug have a
single jaw, semilunar in its form, and denticulated. The tritonia has
two jaws, which act like the blades of a pair of scissars. The other
mollusca posse^ss no organs of this kind ; but have, in some instances,
a sort of proboscis ; as the huccimtm, murex, voiuta, doris, scyllaa,
&c.

In the worms, properly so called, there are sometimes hard parts
forming a kind of jaws or teeth. Thus in the nereis, the mouth pos-
sesses several calcareous pieces. The aphrodite {sea-mouse) has a
proboscis, furnished with four teeth, which it can extend and retract
at pleasure. Within the mouth of the leech are three semi-circular
projecting bodies, with a sharp denticulated edge ; by this apparatus
the animal inflicts its wound of the well-known peculiar form in the
skin.

The teeth of the echinus (sea-hedgehog) are of a very singular ar-
rangement ; a round opening is left in the shell for the entrance of
the food ; a bony structure, on which five teeth are placed, fills up
this aperture ; and as these parts are moved by numerous muscles,
they form a very complete organ of mastication.

The stomach of the vermes is, in general, a membranous bag ; but
in some cases its structure is more complicated. In addition to the
instances mentioned by the author, we may observe that the helix stag-
nalis, and the onchidia have gizzards. The aplysia has three strong
muscular stomachs, provided with pyramidal bony processes. This
structure, together with that of the bulla lignuria, and of the lobster
and crah, presents a new analogy, as Cuvier has observed, between
the membranes of the intestines, and the integuments of the body.
This is particularly strengthened by the annual shedding of the lob-
ster's teeth, when its crustaceous covering falls off".

lis
CHAPTER VII.

ON THE INTESTINAL CANAL.

MAMMALIA.

§ 109. 1 HE intestinal canal (which is the most common part
in the whole animal kingdom after the stomach), is distin-
guished in this class by two peculiarities, which depend on
the mode of nutrition. It is comparatively shorter in carnivo-
rous animals f and there is also in these less difference to
external appearance between the small and the large intestine,
than in the herbivora. Yet these rules are not without their
exceptions. For the seal has very long, and the sloth very
short intestines ; the badger, which is not a proper carnivo-
rous animal, and several true herbivora, as, for instance, the
rell-mouse, (glis esculentus) have no distinction between the
large and small intestine-
It is worthy of notice how the calibre of the intestines and
the strength or thickness of their tunic bear no definite pro-
portions to each other. Hence the small intestines of a full
grown seal, which are very long, and of the size of the little
finger in thickness, have much stronger tunics than those of
the opossum, the calibre of which is equal to the size of the
thumb.*

In considering the proportionate lengths of the intestinal canal,
and the relation which these bear to the kind of food on which the
animal subsists, many circumstances must be taken into the account,
besides the mere measure of the intestine. Valvular projections of
the internal mennbrane, dilatations of particular parts of the canal,
and a large general diameter, compensate for shortness of the intes-
tine, and vice versa. The structure of the stomach must also be
considered ; as, whether it is formed of more than one cavity ; whe-
ther the oesophagus and intestine communicate with it in such a
manner as to favour a speedy transmission of the food ; or, whether

* Vide Pallas, Novcc Species quadrupedum e GUrium ordiite. Erlang, 1778-4.

ON THE INTESTINAL CANAL. 113

there are cub de sac, which retain the aliment for a long time in the
cavity. The formation of the jaws and teeth, and the more or less
perfect trituration and comminution which the food experiences in
the mouth, must likewise be viewed in connexion with the length and
structure of the alimentary canal.

The whole length of the canal is greater in the mammalia than in
the other classes. It diminishes successively, as we trace it in birds,
reptiles, and ßshes, being shorter than the body in some of the latter
animals, which is never the case in the three first classes.

In omnivorous animals, the length of the canal holds a middle
rank between those which feed on flesh, and such as take vegetable
food. Thus, in the ral, its proportion to the body is as eight to one ;
in ihepig thirteen to one ; in ?nan six or seven to one. The diminution
in length, in the latter case, is compensated by other circumstances,
viz. the numerous valvulae conniventes, and the preparation which
the food midergoes by the art of cookery.

In carnivorous animals every circumstance concurs to accelerate
the passage of the alimentary matter. It receives no mastication ; it
is retained for a very short time in the stomach ; the intestine has no
folds or valves ; it is small in diameter ; and the whole canal, when
compared to the body, is extremely short, being three or five to one.

The ruminating animals present the opposite structure. The food
undergoes a double mastication, and passes through the various ca-
vities of a complicated stomach. The intestines are very long ; twenty-
seven times the length of the body in the ram. Hence the large intes-
tines are not dilated, or cellular ; nor is there a ccecum. The soHpeda
have not such a length of canal, nor is their stomach complicated ;
but the large intestines are enormous, and dilated into sacculi : and
the ccecum is of a vast size; equal, indeed, to the stomach. The
Todentia, which live on vegetables, have a very large ccecum, and a
canal twelve or sixteen times as long as the body. In the rat,
which can take animal as well as vegetable food, the canal is shorter
than in the other rodentia.

There are some exceptions to the rule which we have just men-
tioned respecting the length of the canal in carnivorous and herbi-
vorous animals. The seal, which takes animal food, has very long
intestines : the sea-otter resembles it in this respect, and differs
therein most remarkably from the common otter, which resembles
other carnivorous animals in the shortness of its intestinal tube.
The length of canal in the former is twelve times that of the animal ;
and only three times and a quarter in the latter. (Home, in the
Fhilos. Truns. 17Ü9, part 2.) Whales have likewise a longer canal
than other carnivorous mammalia; their stomach is complicated,
and the intestine has longitudinal folds. It seems, therefore, that a
considerable length of intestinal canal is found in all mammalia
which live much in the water, although they are carnivorous.

The plantigrade animals, which have carnivorous teeth, but feed
equally well on vegetables, have a long canal ; but it is very narrow,
and possesses no cnccum, nor distinction of large intestine.

1

114 ON THE INTESTINAL CANAL.

A species of bat {vespertilio noctula), seems to have the shortest
intestinal canal of any mammalia : it is only twice the length of the
animal's body. On the contrary, the roussette (vesp. vmnpyrus, Linn. v.
caninusi Blmiai.) which lives entirely on vegetables, has it seven times
as long.

A remarkable difference is observed in the length of the canal be-
tween the wild and domesticated breeds of the same species. In the
tvild boar the intestines are to the body as nine to one ; in the tame
animal these proportions are as thirteen to one. In the domestic
cat, five to one ; in the ivild cat, three to one. In the bull, twenty-
two to one ; in the buffalo, twelve to one. They are, on the con-
trary, longer in the wild than in the tame rabbit ; the proportions in
the former being eleven, and in the latter nine to one.

The proportion of the intestinal canal to the length of the body in
birds, is as two, three, four, or five to one. It is not always longest
and largest in the graminivorous species, as many piscivorous birds
have it equally long.

It is hardly twice the length of the body in many reptiles ; and not
60 much in the frog, although it is nine times as long as the space
between the mouth and the anus in the tadpole.

The alimentary canal of some fishes is continued straight from the
mouth to the anus, and does not therefore equal the length of the
body. The lamprey, skate, and shark, are thus circumstanced.

§ 110. The valvulse conniventes of the small intestine are
more faintly marked in most mammalia than in man ; in some,
indeed, they do not exist at all, and this happens both in car-
nivorous and herbivorous animals. In the cetacea, on the
contrary, the internal surface of the intestines has longitudinal
folds of a zig-zag appearance.

The possession of a villous coat for the absorption of the
chyle constantly distinguishes the small from the large intes-
tine, which seems to be merely destined for the reception of
the faeces. The villi are remarkably long and numerous in
the bear.*

The Fallopian valve (^alvula coli) is wanting in a few ani-
mals only of this class, as, for instance, in the hedgeliogfy
ornithorhynchus, and racoon.

* On the structure of this coat in several species of the four classes of red-
blooded animals, see Roun. Ad. Hedwig, Disquisitio ampullulanium Lieberkiihii.
Lips. 1797-4; Rudolphi's Anatomische physiologische Abhandlungen ; and Meckel's-
Archiv V. B. 1819.

t Roederer gives an accurate description of this valve in our domestic animals,
De Valvula coli. Argent. 1768, 4to. p. 46.

ON THE INTESTINAL CANAL. 115

§111. There is great variety with respect to the coecum in
this order, even in the different species of the same genus.
Many, particularly of the Carnivora, have none; it is also
wanting in some herbivora, as the rell-mouse. In others of the
latter description it is often of enormous size. Thus in the
hare and rabbit it is longer than the whole animal, and fur-
nished internally with a peculiar spiral valve. The marmot
of the cape, (Jiyrax capensls) has first a large ccecum, and
then, further on, two other conical blind appendices.*

The appendicula vermiformis is wanting in many mammalia;
even in some of the simice, as the silvanus, &c.

Most of the animals which have a vertebral column, have the
intestine divided into two parts ; viz. the large and small. The lat-
ter is commonly the longest, smallest in its diameter, and villous on
its internal surface. The former is often thicker in its coats, and
very rarely villous. In those mammalia which have this distinction,
the separation is marked by one or more appendages, which have
the name of cceami when large, of vermiform appendix when slender.
Man, the orang-outang, and the phascolome, (a species of rat having
an abdominal pouch, from New Holland) are the only animals
which have both coecum and appendix. The ornitJiorhynchus hystrix
has an appendix only; and most other mammalia have only a coecum.
All the siviüs, except the orang-outang, have a ccecum, like that of
man, but want the appendix vermiformis.

Several possess neither ccecum nor appendix, as the edentata,
(except the proper ant-eaters) ; the tardigrada, the bats, the planti-
gradfi, except the ichneumon, the mustelw, and the myoxi (^dormice) ;
and the cttacea.

A taliula coli shews the distinction between the large and small
intestine, where the ccecum is wanting ; as in the sloth and armadillo.
When this distinction does not exist, the large intestine is charac-
terized by the want of villi, by a greater thickness of its coats, and
particularly by a strong layer of longitudinal muscular fibres.

In animals, which have a ccecum, this part appears to be merely a
prolongation of the large intestine below the termination of the small.
Yet in some cases, the large intestine retains only for a short space
the same structure which the ccecum possessed, as in the flying"
lemur, {ijaleo]>itliecus) the oposauni, most of the rodentiu and ruminantiu.
In the herbivorous mammalia the ccecum is generally large and cel-
lular; and it is even so in omnivorous animals, as in jnan, in the
genus sivii/i, and lemur. In the rundnanlia, where the stomach is
very complicated, the ccecum is of a moderate size, and uniform. It

* Pallas, Spicilegia Zoobgica, torn. ii. tab. 3, fig. 7, 8.

I 2

116 ON THE INTESTINAL CANAL.

is large and cellular in the flying lemur and opossum, which are sup-
posed to live much on animal substances.

The ccecum of the true carnivorous mammalia is constantly small,
and uniform in its cavity ; and the rest of the large intestine has the
same characters. The large intestine of the herbivora is cellular,
excepting the ruminantia and some of the rodentia.

It may therefore be stated as a general rule, that the existence of
a large coecum shews that the animal feeds on vegetables ; and that
carnivorous mammalia have either none, or a very small one

The ornithorhynclms paradoxus and hystrix have the end of the
rectum forming a cloaca, as in birds. The urinary bladder opens
into this part. The penis of the male is contained within it ; and
the horns of the uterus open into it in the female. Home in the
Philos. Trans. 1802, pt. 1, of the omithorhynchus paradoxus, pt. 2, of
the omithorhynchus hystrix.

§ \12. In most herbivorous animals of this class, the colon
is large, long, and divided into cellular compartments. This
is remarkably the case in the elephant and horse. The large
intestine of the latter is twenty-four feet long ; while, on the
contrary, in a moderate sized dog it is about six or eight inches.
The rectum of the latter has strong transverse folds which con-
tract it, and render the evacuation of the faeces difficult.

In a few instances, as in the beaver and sloth, but most re-
markably in the omithorhynchus ^ the rectum and urethra have
a common termination, which may be compared to the cloaca
of birds.

As we have spoken above of the be^oars and other concre-
tions formed in the stomach, we must here take notice of the
Intestinal stones which occasionally occur in horses, and of
the valuable faecal concretions of the pike-headed whale "or
cachalot {physeter macrocephalus).

The former are commonly of a yellowish grey colour ; of a
globular form, shining externally, but of a dead and earthy ap-
pearance; when broken, not very hard; and in their ave-
rage size about equal to a billiard ball, although they have been
found as large as a man's head : all these external characters
vary indeed considerably. The most remarkable circumstance
relating to them is their composition ; according to Fourcroy's
and Klaproth's Analysis, they consist in the proportion of one
half of phosphate of magnesia. They are often found in

ON THE INTESTINAL CANAL.

117

millers' horses, which have been fed for a long time with bran
and mill-dust ; there is usually only one, but sometimes more ;
they are most frequent in the colon, and have very seldom
been found in the stomach. They are not discovered in ge-
neral until the death of the animal; but I find an instance, in
the Epistolcs de Re Numismatica ad Z. Goezium, of a horse,
which voided a stone of the above-mentioned kind, as large as
a hen's egg, every month with his faeces.

A species of globular concretions, very different from
these intestinal stones, is occasionally found in the colon and
coecum of the horse. It is composed of fine vegetable fibres,
and resembles, on the first view, the balls of the chamois.
Hence Lafosse, who has described and delineated them, calls
them cegagropilce, by way of distinction from the true intes-
tinal stones, which he terms hezoar equinum.^ Like the balls
of the chamois, they are much lighter than intestinal stones ;
and two of them are not unfrequently found together, one
being inclosed within the other.

The faecal indurations of the cachalot form the valuable
substance known by the name of ambergris, which was for-
merly considered as an animal excrement, but has been sup-
posed latterly by some to be a fossile substance, by others to
be a vegetable resin : its animal origin is now placed beyond
all doubt. Sir Joseph Banks informed me, that according to
what he could learn from the English South-Sea whalers, the
faeces of the cachalot, which are nearly fluid in a healthy
state, are hardened into this ambergris by a kind of constipa-
tion ; hence it is only found in weak and exhausted animals,
and the firmest and most valuable comes from such as seem to
have died of the complaint which it has occasioned.

BIRDS.

^113. The alimentary canal in birds is much shorter than
in the mammaha ; it is also generally shorter in carnivorous

• See his Coun d'Hippiatrique, p. 158, tab. 51.

lis ON THE INTESTINAL CANAL.

birds than in such as derive their food from the vegetable
kingdom. There is hardly any perceptible external difference
between the large and small intestine ; indeed, the commence-
ment of the canal is often larger than the termination.

§ 114, Most birds have two coeca, which are of considerable
length in some species of the gallinaceous and aquatic tribes.
They are characterized in the ostrich,*^ by a remarkable spi-
ral valve. Some few aquatic birds have only a single ccecum ;
and some, particularly among the birds of prey, want it en-
tirely.

§ 115. The rectum ends in a part called the cloaca, which is
an expanded portion, containing the termination of the ureters,
the genital organs, and the bursa Fabricii. This latter part
varies in form in the different species, being oval or elongated,
&c. ; it is largest in young birds, and is so contracted in older
ones, that it will hardly hold a millet-seed in an old cock.f In
the ostrich the cloaca forms a large spherical bladder ; a si-
milar structure is observed in the goshawk and in the grey
heron.

The bursa Fabricii is an oval membranows bag, situated at the up-
per or back part of the cloaca, into which it opens by a slit-shaped
aperture. Its size is proportionate to that of the animal ; being one
inch and a quarter long in the goose, and half an inch broad ; and
about a quarter of an inch long in the sparrow. According to the
accurate observations of Mr. Macartney, its coats contain numerous
glandular bodies which furnish a mucous secretion. (Article Birds
in Rees's Cyclopedia.)

AMPHIBIA.

I 116. We shall take only one species of each of the two
chief divisions of this class by way of examples.

The intestinal canal of the hawks-bill turile (testudo caretta)
is five times as long as the whole animal ; the small intestine
is larger than the short portion of large intestine. Both por-
tions have longitudinal folds internally, and are covered with
an abundance of mucus, which is the case in the whole dass^.

* See Valisnieri Notomia dello Struzzo, tab. 2, fig. 1, 2.
t S, Collins's System of Anatomy, vol. ii. tab. 73.

ON THE INTESTINAL CANAL. 119

I found these folds so large and numerous in the rectum, that
a transverse section of the gut presented the appearance of a
broad radiated ring.

That portion of the small intestine which corresponds to
the jejunum was beset, in the animal which I dissected, with
innumerable small processes, like the appendiculce einploicce^
which are occasionally found in some mammalia.

I 117. In the ringed-snake, {coluber natrix) the whole
length of the intestinal canal does not equal that of the ani-
mal. The small intestine forms a very considerable ya^/opm^z
valve, by a prolongation at its entrance into the large. The
termination of the small, as well as the large intestine, the sto-
mach, and the oesophagus (which is one third of the length of
ihe whole animal) have longitudinal folds * internally.

FISHES.

^118. The intestinal canal of this class, with a very few ex-
ceptions, is extremely short. In some, as the torpedo,-\ it is only
half as long as the stomach. However, the passage of the
chyle, and afterwards of the faeces, through the intestine, is
lengthened in this, and some other cartilaginous fishes, by a
spiral valve. J

In the structure and formation of the coats of the intestinal canal
there are not many differences in the inammalia. True valvidce conni»
ventes seem peculiar to ?}ian and the monkeys. But the internal sur-
face of the intestine is always villous, and generally deserves that
appellation more than in the human subject. Some of the Carnivora, as
the dog, have very long villi, and this class has, in general, more
muscular intestines. A considerable number of mucous glands is
found near their coecum, when they have one. But the seal has these
glands in greatest number, and most distinct. They form, in that
animal, a regular and unbroken series through the whole length of

• See Charas, Nouvelles Ei-periences mr la Viptre. Par. 1672, 8vo.; and Tj'son's
Anatomy of a Rattlesnake. Philos. Trans, vol. xiii. No. 144.

t Lorenzini, Ouervazioni inlarno alia Torpedhte. Fior. 1678, 4to. tab. 2.

t It is delineated from another species of ray by Swammerdam, in the 4th edi-
tion of Bartholin's Anatomy. Lugd. Bat. 1673, p. 297 ; whicii contains much va-
luable information in zootomy. Perrault has represented it in a shark, Essais de
I'hyiiqne, vol. iii.

120 ON THE INTESTINAL CANAL/

the lower portion of the small intestine, and are very visible on ac-
count of their colour.

The villous coat of the intestine forms numerous oblong processes
in the rhinoceros. (Philos. Trans. 1801, pt. 1.)

The viUi in the small intestine of birds are remarkably long, nu-
merous, and elegant. They are most distinct and clearly developed
in the graminivorous birds. In the ostrich they are rather flat thin
laminae than villi, but at the same time long and numerous, so as to
present a very elegant structure. The large intestine of birds is uni-
form on its surface, but the ostrich presents a very remarkable devia-
tion, for its large intestines, which are very long, have numerous
transverse folds like the valvulse conniventes of man.

The intestine of the turtle is covered with innumerable thin longi-
tudinal processes, lying close together, and increasing the surface of
the gut to a vast extent. These are most numerous in the upper
part of the intestine, and gradually diminish in number below, until
they cease altogether. In this respect they resemble the valvulse
conniventes of man, and the villi of all animals. For these structures
are always most distinct at the commencement of the canal, where
absorption of the chyle goes on to the greatest extent. As the ali-
mentary matter becomes deprived more and more of its nutritious
parts, as it descends in the intestine, a less complicated apparatus for
absorption exists in the lower part of the canal, and is sufficient for
taking up the small remains of really nutritious parts. This circum-
stance is illustrated in the longitudinal folds of the cetaceous animals.
At the commencement of the intestine there are four or five of these ;
at different distances we meet with four, three, two, one, and lastly
the surface is completely uniform.

§ 119. The appendices pyloricce (which are found in all
fishes, with a very few exceptions, as the pike) sometimes open
at the lower orifice of the stomach, but generally at the com-
mencement of the intestinal canal, and secrete a fluid, which
seems to have considerable influence on the business of diges-
tion and chylification, * which is performed in these animals in
a very short time. They have generally the appearance of
small blind appendices,i- and their number varies in the differ-
ent species, from one to several hundred. In some cartilagi-
nous fishes they are as it were consolidated into a glandular

* The leading work on this subject is very rare, Fan altera Observ. Anat. Colle-
gii privati. Amstelod. ; which was produced almost entirely by Swammerdam.

t In some, as the burbot, they appear almost like a finger. Hence, the part has
been called the burbot's hand or foot. See Chr. Encelius De Re Metallica^
Francof. 1551, p. 241 ; which contains, I believe, the first delineation of the part.

ON THE INTESTINAL CANAL. 121

body, * which has been compared to the pancreas of warm-
blooded animals.

INSECTS.

§ 120. Similar blind appendices {vasa varicosa of Swam-
merdam) are found on the short alimentary canal of several
insects, which is particularly distinguished from that of red-
blooded animals by the want of mesentery, f Some zootomists
have considered these appendices as small intestines, others
as biUary ducts, and others as lacteal vessels.

VERMES.

§ 121. Several mollusca have these appendices on both sides
of their short intestinal tube, as the aphrodite aculeata.
Those testacea which remain fixed in one situation, have a
shorter and more simple intestinal canal than those which have
the power of locomotion. The rectum, according to Poli,
passes directly through the heart in most of the bivalves. In
the slug, {Umax) as well as in the similar animal, which inha-
bits a shell, {helix) the rectum opens on the front of the lim~
bus, close to the air-hole. The leech can hardly be said to
possess an intestine ; yet it has an anus at the end of the tail,
from which some little faecal matter is discharged, most of this
being evacuated by the mouth. The armed polypes have no
opening of this kind.

As the part of his work which the author has devoted to the ali-
mentary canal of the lower orders of animals is very short, and as the
subject is interesting in many points of view, it seems right to sub-
join a somewhat more ample account.

The simple globular hydatid, which is frequently found in the dif-
ferent viscera both of man and quadrupeds, has been supposed by
some to be an animal consisting entirely of a stomach. Doubts, how-

* The consequences which may be drawn from this circumstance towards the elu-
cidation of the business of secretion, have been already pointed out in my Instit.
Physiol, p. 401, edit. 4.

t On this subject, as well as on several of the following chapters, the references
contained in the notes to the 107th and 108th paragraphs may be consulted. See
also Ramdohr, über die Vardauungiwerkzeuge der Insecten.

122 ON THE INTESTINAL CANAL.

ever, have lately been raised, whether this be really an anim^.
The reader, who wishes to see the arguments on both sides of the
question, may consult the " Observations on the Manner in ivhich Hy-
datids grow and multiply in the Human Body," by John Hunter, M. D.
in the 1st vol. of the Transactions of a Society for tlie improvement of
Medical and Chirurgical Knotoledge ; and the note to the 83d para-
graph of this work. Even if it were allowed that these bags are ani-
mals, it does not follow that their cavity is a stomach ; and the at-
tachment of the young to the sides would rather justify us in consi-
dering it as the organ of generation.

The hydatid, which is more frequently found in animals, which
possesses a head and mouth like the taenia, enabling it to attach itself
to parts, and which can be seen to move when placed in warm water,
is generally allowed to possess an independent vitality. But whether
the bags of water, which form its body, be a stomach, is certainly
doubtful.

The most simple form of an alimentary cavity exists in the com-
mon fresh- water polype (hydra). It appears to be excavated in the
substance of the body, and has a single opening, situated in the cen-
tre of the space surrounded by the tentacula. The nutritive matter
soaks immediately into the body, and imparts its colour to the
animal.

The large masses of gelatine, called medusce, which resemble in
form mushrooms, and are found floating in the sea, have a somewhat
similar structure. A stomach is hollowed out in the pedicle, and
vessels, commencing from its cavity, convey the nutritious fluid over
the body. Sometimes the stomach has a simple opening ; in other
cases there are branching tentacula, on which canals commence by
open orifices : these unite together to form larger tubes, and the suc-
cessive union of these vessels forms at last four trunks, which open
into the stomach, and convey the food into that cavity. This very
singular structure constitutes a remarkable analogy to the roots of
trees ; and Cuvier has formed a new genus under an appellation de-
rived from this comparison ; viz., the rhizostoma, from |t^a, a root,
and errofji.cc a mouth.

The star-fish (asterias) has a membranous cavity in the centre of
its body, communicating externally by a single opening. Two ea^
nals extend from this into each of the branches, or as they are some-
times called the fingers of the animal, where they suihdivide, and form
numerous blind processes.

The tape-worm [tcenia] has a small canal running on each side of
its body ; the two tubes are joined together by transverse productions
at each joint.

The ascaris lumbricoides (round- worm) has a simple canal running
from one extremity of the body to the other.

The leech (Jiirudo sanguisuga, or medicina lis) has a short oesophagus
and a very large stomach, divided by numerous membranous septa,
which are perforated in the centre. Jt has been generally supposed
that this animal has no anus ; but Cuvier says that it possesses a

ON THE INTESTINAL CANAL. 123

very small one. (Legons d' Anat. comp. torn. iv. p. 141 ; Dumeril,
on the contrary, denies its existence. Zoologie Anatomique, p. 298.)

The common earth -luonn {lumbricus terreslris) has a long canal di-
vided by several partitions.

The aphrodile aculeata has an intestine running according to the
length of the body, and sending off on each side several blind pro-
cesses which enlarge at their termination.

In the proper inollvsca, besides the stomach, which has been al-
ready noticed, there is an intestine, seldom of considerable length,
making some turns in its course ; it passes, in all the acephalous mol-
hisca, through the heart.

The intestinal canal of insects varies very much in the different
genera and species. It may be stated on the whole, that a long and
complicated intestinal tube denotes that the insect feeds on vegetables ;
while the contrary characters indicate animal food.

Great difference is found, in some instances, between the kirva and
the perfect insect. The voracious larva of beetles {scarabcei) and
butterflies have intestines ten times as large as the winged insects,
which are produced from them.

In the dragon-fly, {libcllula) which is very carnivorous, the intes-
tine is not longer than the body. There is a small but muscular sto-
mach.

The orthopiera (which class contains the locusts, &c., well known
for their destructive powers) have a long and complicated alimentary
apparatus. I'hey have first a membranous stomach. This is sjic-
ceeded by another cavity covered internally with scales or teeth, and
possessing a very thick muscular coat ; in short, a true gizzard.
Round the end of this the coecal processes are attached. There is,
lastly, an intestinal canal differing in length and diameter.

The alimentary canal runs straight along the body in the cntsiacea,
and is uniform in its dimensions, excepting tlie stomach.

124

CHAPTER VIII.

ON THE LIVER, SPLEEN, AND OMENTUM.

§ 122. We may conveniently collect together, in this chap-
ter, whatever is to be said concerning the liver, spleen, and
omentum ; since these parts are connected with each other in
their functions.

The spleen and omentum seem to be less constantly found
in the animal kingdom than the liver, and to be in a manner
subservient to the latter viscus ; which, on the contrary, exists
in every class and order of animals that is provided with a
heart and circulating system.*

MAMMALIA.

§ 123. Besides the less important variations in size, colour,
division into lobes. Sec., the liver of these animals is distin-
guished by two chief differences ; first, in some genera and
species it transmits all the bile immediately into the duodenum.
Secondly, in several others a part of this fluid is previously
collected in the gall bladder. Animals of the horse -f and goat
kind, and some of the cetacea, afford instances of the want of
this receptacle.

On the contrary, in some of those which have it, there are
Jtepatico-cystic ducts, which convey the bile immediately from

* On the liver, in the different classes of animals, see N. Mulder De functione
hepatis, in disquisitione illius visceris nixa. Leyd. 1818 ; also F. Ebeling De pulmo-
num cum hepate Antagonismo. Getting. 1806. On the spleen, see Wilbrand, in
Oken's Ms, 1821, vol. vi, p. 543.

+ An enumeration of the mammalia, which have no gall-bladder, will be found in
P. Trott De vesiculcB fellece defectu. Erlang. 1822, 4to. Some have considered
the large hepatic duct of the horse as a gall-bladder. See Sir Thomas Brown's
Pseudodoxia Epidemica, p. 119, ed. of 1672. This might with more truth be said of
the elephant, where the hepatic duct has a considerable expansion just at its entrance
into the intestine. (Euvres de Pierre Camper, torn, ii» ch. 4, § 3.

ON THE LIVER, SPLEEN, AMD OMENTUM. 125

the liver into this bladder, as in the horned cattle. It deserves
to be remarked here, as a peculiarity of the liver of some four-
footed mammalia, which live in or about the sea, namely, the
polar bear and some seals, that it seems to possess some poi-
sonous or noxious qualities v^^hen employed for food. Heems-
kerk's companions experienced this in the former instance at
Nova Zembla ; and Lord Anson's squadron in the latter, on
the coast of Patagonia.

In the ox and sheep the spleen is distinguished by a pecu-
liar cellular* structure from the merely vascular texture which
it possesses in other animals of this class. Perhaps this differ-
ence in texture may lead to the discovery of the true functions
of this viscus, the use of which is at present unknown. +

Mammalia\ alone possess a true and proper omentum ; and
the part which has been called a spleen in other animals is
very different in its structure, connexions, &c. from the same
viscus as it exists in this class. I quote only a single instance
of the peculiar appearances of the omentum in particular spe-
cies ; viz. that of the racoon, (ursus lotor) which has a very
remarkable structure. It is comparatively large, and consists
of innumerable stripes of fat, disposed in a reticular form, and
connected by an extremely delicate membrane, resembling a
spider's web, I have also found it particularly large in an old
lioness.

The liver of mammalia is in general divided into more numerous

* Stukeley on the Spleen, tab. 3 and 4.

The hepatico-cystic ducts, and the cellular stracture of the spleen, are the mope
worthy of mention, as they have given rise to errors in physiology.

t On the singular pustular eruption, which sometimes appears on the spleen of
hydrophobic animals, as the dog, fox, and cat, see Locher, Magnum lienis in hy-
drophobia Momentum. Gott. 1822. A similar conformation has been discovered by
Neergaard in the Racoon. See his Vergleichende Anat. der Verdauungsiverkzeuge,
§ 6. fig. 4.

} See A. G. Stosch De omentis Mammalium, partibusque Ulis similibua aliorum
Animalium. Berol. 1807. A description of the spleen in many birds, amphibia, and
fishes, will be found in Moreschi della Milza in tutti gli Animali vertebrali. Milan,
I8f)3 ; also C. F. Heusingpf, über den Ban ttnd die Verrichtung der Milz. Thionv,

iai7.

i^ ON THE LIVER, SPLEEN, AND OMENTUM.

iobes, and the divisions are cai'ried deeper into its substance, than in
the human subject. This is particularly the case in the Carnivora,
where the divisions of the lobes extend through the whole mass.
But the utility which Monro has assigned to this structure ; viz. that
of its allowing the parts to yield and glide on each other in the rapid
motions of the animal, carries very little plausibility with it. {Essay
on comparative Anatomy, p. 11.)

In many animals of this class, as the horse, the ruminantia, the pa-
chyJermata, and whales, the liver is not more divided than in man.

The ductus choledochus forms a pouch between the coats of the in-
testine, for receiving the pancreatic duct, in the cat and elephant.

All the quadrumana, Carnivora, and edentata have a gall-bladder.

Many rodentia, particularly among the rats, want it. The tardi-
grada ; the elephant and rhinoceros, among the pachydermata ; the
genus cervus arid camelus among the ruminating animals ; the so-
lipeda ; the trichecus and porpoise also want this part. It does not
exist in the ostrich and parrot, but is found in all the reptiles. Cu-
vier thinks that it belongs particularly to carnivorous animals ; that
it is connected with their habit of long fasting, and serves as a reser-
voir for the bile.

All the mammalia which want it, except the porpoise, are vegetable
eaters ; and most reptiles, which universally possess it, live on animal
food. {Legons d'Anat. comp. torn. iv. p. 37.)

The valvular transverse folds of the cystic duct belong only to the
simicE, besides the human subject.

The spleen of the oi-nithurynckus hystrix is composed of two lobes ;
the anterior somewhat long and thick, the posterior broader and thin-
ner. Both run obliquely towards the right side to meet at an acute
angle in the left hypochondrium. The texture is loose and spongy.
See.Meckel De Omithorhyncho parudoxo, p. 46, Lips. 1826.

BIRDS,

§ 124. The liver is much larger in domesticated than in
wild birds. * It is well-known that the gall-bladder is want-
ing in many species of this class, (for instance in the pigeon^
parrot, &c.) and sometimes in particular individuals of a spe-
cies, which commonly has it, as in the common fowl.

A roundish lump of fat, which covers the intestines of some
aquatic birds, has been considered as an omentum.

The liver of birds is divided into two equal lobes. The hepatic
duct opens separately from the cystic, and its termination is generally,

* B. Robinson On the Food and Discharges of Human Bodies. London, 1748-8,
p. 97.

ON THE LIVER, SPLEEN, AND OMENTUM. 137

but not always, preceded by one or more pancreatic ducts, and fol-
lowed by that of the cystic duct.

The fundus of the gall-bladder receives branches from the hepatic
duct, but that tube sometimes unites with the cystic, as in the
duck.

AMPHIBIA.

§ 125. The liver, in these animals, is universally of consi-
derable size ; and in some instances, as the salamander, of im-
mense magnitude. I know no species in which the gall-bladder
is wanting.

The yellow appendices {ductus adiposi, appendices lutece)
which are found in theyro^, on either side of the spine, above
the kidneys, and sometimes form one mass, sometimes are di-
vided into several smaller portions, were considered by Mal-
pighi as a kind of omentum.* That this resemblance ijS very
remote, appears from several circumstances ; and particularly
from the constant and remarkable variations of size which oc-
cur in these parts at the pairing season.

In the tortoise the liver has a peculiar conformation. It is divided
into two round ii-regular masses, of which one occupies the right hy-
pochondrium, and the other rests on the small curvature of the sto-
mach. Both are connected by two narrow branches of the same
structure, into which the principal vessels run. In the green lizard,
in the geckos, dragons, iguanas, it forms only a single mass, flat or
convex below, and concave above. Its free edge in the dragons has
two fossae, which divide into three lobes, of which the right is pro-
longed into a sort of tail. In the geckos it has only one fossa, and
the right side is also longer than the left. In the common iguana it
extends into a long appendix. In the crocodiles and chameleons the
liver has two distinct lobes. In the latter it has also a long appendix.
It has but one lobe in the serpent tribe, in which it is long and cylin-
drical. There is but one also in the salamanders, but there are two
in the frog genus.

FISHES.

§ 120. In many animals of this class, the short intestinal
canal is surrounded, and as it were consolidated with a long
liver. Some fishes, which are almost destitute of fat in the

• De Omenta el Adiposis Ductibtis, Opcr. torn, ii. p. 35, &c.

128

ON THE LIVER, SPLEEN, AND OMENTUM.

rest of their body, have an abundance of oil in the liver ; as,
for instance, the sJcate and cod. It is wanting in some few
species.

The spleen gradually diminishes in size from the mammalia to
fishes. In the porpoise there are several small spleens ; supplied
from the arleries of the first stomach. It is always attached to the
first, when there are several stomachs.

In birds it is always near the bulbus glandulosus ; but does not
lie constantly very close to the stomach in reptiles ; as it is found in
the mesentery of the frog. Neither is it very uniformly situated in
fishes.

The size of the liver is generally very considerable ; its colour is
frequently yellower than in reptiles, and its divisions are as uncertain
as in the three preceding classes, so that they frequently vary, even
in the different species of the same genus. Its consistence is also
less compact than in the three classes ; hence its parenchymatous
texture readily dissolves in spirits of wine, and leaves the vessels of
the liver exposed. In general its divisions are few ; very frequently
it only forms one mass, sometimes however it has two lobes, occa-
sionally three, but very seldom more.

It rarely happens that the different branches of the hepatic ca-
nals unite in one duct, they open successively into the gall-bladder
or its canal, whence the whole of the bile is conveyed into the intes-
tine. The diameter of the cystic duct is always much larger than
that of the hepatic, but its size does not increase after its junction
with the other ducts. In the rays the gall-bladder receives several
very fine hepatic canals; afterwards the hepatic canal furnishes a
principal branch, which comes from the middle lobe of the liver,
and joins the cystic duct at a short distance from its origin. The
different branches of the hepatic canal unite in the syngnathus pelagi-
cus into one trunk, which joins the cystic duct. In the ietrodons, the
hepatic canals have three principal branches, the first of which joins
the gall-bladder, a little on one side of its neck, and the second and
third open into the cystic duct, a little beyond its origin.

INSECTS.

§ 127. An organ secreting bile, and which may therefore
be regarded as a liver, is found in such animals only of this
class as have a heart and system of vessels, viz. in the genus
cancer.* We have already observed, that the blind appen-
dices found in several others, have been considered as biliarv
organs.

* Willis De Anima Brutorum, tab. 3. Rösel, vol. iii. tab. 58 and 59.

ON THE LIVER, SPLEEN, AND OMENTUM, 129

The large adipose substance which occupies the greatest
part of the body of larvae, and of several insects, has appeared
to some zootomists to resemble the omentum.*

VERMES.

§ 128. The organs which secrete and contain the fluid of
the cuttle-fish have been regarded as of a biliary nature.
Thus, the mytis has been called the liver, and the ink-bag
the gall-bladder.i-

Several testacea, particularly among the bivalves, have a
liver surrounding their stomach, and pouring its bile into the
cavityif: of that organ. In many snails it occupies the upper
turns of the shell. §

A liver exists in all the molliisca, and is very large ; but this class
has no gall- bladder. The liver is supplied with blood from the aorta,
and there is consequently no vena portarum.

It is a completely mistaken notion, that the black fluid of the
cuttle-fish is its bile. The ink-bag is indeed found between the two
lobes of the liver in the sepia octopus ; and in front of them in the
calmar ; but in the common cuttle-fish, (sepia officinalis) it is at a
considerable distance from this organ.

The real bile is poured, as usual, into the alimentary canal.

In the gasteropodous mollusca, as the snail, the liver is very large,
and consists of several lobes, having each an excretory duct. They
surround the stomach and intestine, and open by several mouths into
its cavity. The aplysia, onchidium, doris, &c. have a similar struc-
ture.

In the acephalous division of this class, it surrounds the stomach,
and pours its secreted liquor into that cavity by many openings ; the
oyster and muscle exemplify this.

The proper worms, {vermes of Cuvier) the echinodermata and
zoophytes have nothing analogous to this gland.

The author has entirely omitted speaking of the pancreas in this
part of his work ; probably because there are no remarks of much

* Lyonet, Anatomie de la Chenille, &c. tab. 5 and 13 ; and Treviranus, über den
inaern Bau der Arachniden, tab. 1, fig. 8.

t Compare the representations which have been given by Swammerdam, Turber-
ville, Needham, and Monro; and Tilesius De i-espiratione Sepice nfficinulis, tab. 1,
fig. 1.

X See Poli, vol. i. where he represents this fact in several of the testacea.

§ Swammerdam, tab. 5 of the helix pomalia; and Sal. Stiebel, Limnei amnalis
Uagiuilis Anatome, Gotting. 1815.

K

130 ON THE LIVER, SPLEEN, AND OMENTUM*

importance or interest to be made on the subject. The structure of
this gland in the mammalia, in birds, and in reptiles, is the same, on
the whole, as in the human subject : its form and size, its colour and
consistence, and its division into lobules, exhibit some slight and
unimportant variations.

The termination of its duct or ducts is distinct in birds from that
of the ductus choledockus. In the mammalia they generally open to-
gether, or there is a branch terminating in the ductus cHoledochus,
and another opening into the intestine, as in the dog and elephant, or
they may be quite distinct, as in the hare, porcupine, and marmot.
They may be separate or distinct in different individuals of the same
species, as in the monkeys.

The skate and shark have a pancreas similar to that of the three
|irst classes of red-blooded animals. In other fishes the situation of
this organ is occupied by the c<£cal appendices or pyloric caeca ; which
afford a copious secretion, analogous, no doubt, to the pancreatic
liquor. (These are mentioned in § 119.) The internal surface of
these tubes becomes very red on injection, and possesses a glandular
^.nd secreting appearance.

The appendices, which form separate tubes in most fishes, are
collected in the sturgeon into one mass, which is surrounded by mus-
cular fibres. In this body, which has a very manifest glandular
structure, the tubes join together, and open into the intestines by
three large orifices.

131

CHAPTER IX.

ON THE URINARY ORGANS.

§ 129. These emunctory organs do not exist in several ani-
mals which have a biliary apparatus. They are confined to
the red-blooded classes; all of which have kidneys, while
some orders and genera have not an urinary bladder.

MAMMALIA.

I 130. In some animals of this class, as the bears,* the kid-
ney resembles a bunch of grapes, being composed of several +
small and distinct portions, which are connected by means of
their blood-vessels and ureters with the common trunks of
those vessels. In many of the palmata, as the seal and the
otter, the renal veins form a kind of network, the reticulations
of which intersect the furrows between the mammary pro-
cesses on the outer surface of the kidneys. The suprarenal
glands, {glandulcB suprarenales) as their name implies, are
intimately connected with the kidneys ; but their functions, as
well as those of the thyroid and thoracic glands, still remain
unknown. They appear, from the latest anatomical re-
searches, to have a great sympathy with the sexual organs.:^
The urinary bladder is more loose § in the abdomen of most
quadrupeds than in the human subject. It is comparatively
much smaller in carnivorous than in herbivorous animals ; and
is particularly large in the ruminating bisulca and the hare.

■ Eustachi! Tab. Anat. tab. 4.

t la the bear tliere are fifty or more, see H. F. Fleming, Deutscher Jäger,
J^ipzig. 1719, p. 126.

t See J. F. Meckel's Abdandluiigen aus der menschlichen luid vergleichenden Ana-
tomie. Halle, 1806.

^ \' e.%3.\ü. Analomicarum Fallnjni Obscrvulionum Examen, p. 126. Kiolani Anthro-
pngraphia, p. 241.

K 2

132 ON THE URINARY ORGANS.

Urinary stones, often of very considerable size, are found
not unfrequently in horses, whose intestinal concretions have
been already noticed. Their composition differs considerably,
according to the investigations of Fourcroy and Vauquelin,
from the urinary stones of man ; since they contain neither
phosphoric nor lithic, but carbonic acid.

The structure of the kidney in mammalia displays two very oppo-
site varieties, which may be called the siinple and the conglomerate
kidneys. In the former there is a single papilla, which is surrounded
by an exterior crust of the cortical substance. This is the case in all
the fera ; and in some other animals, as many rodentia. The other
kind of kidney consists of an aggregation of small kidneys, connected
by cellular substance. It appears that this form of the gland is found
in all those mammalia which either live in, or frequent the water.
I have observed it in the seal and porpoise, where the small kidneys
are extremely numerous, and send branches to the ureter without
forming a pelvis, Mr. Hunter states that it belongs to all the
whales. (Phi/os. Trans. 1807, pt. 2.) The otter has the same struc-
ture ; but its small kidneys are not so numerous as in the animals
above-mentioned. (Home, of the sea-oiter, {lutra marina). Philos.
Trans. 1796, pt. 2.) It is remarkable that the brown bear, {ursus
arctos) which lives on land, should have this structure as well as the
white polar bear, {ursus maritimus) which inhabiting the coasts and
floating ice of the northern regions, spends much of its time in the
water. Mr. Hunter {loco citato) concludes, that it is because Nature
wishes to preserve an vmiformity in the structure of similar animals.
But the badger, (ursus meles) which is a very similar animal, has the
uni-lobular kidney. The number of small kidneys in the bear is 50
or 60 ; and it appears that each consists of two papillae. (See the
account of the dissection of a bear, by the French Academicians;
which is also given in Blasius's Collection. Axiatom. Animal, tab. 32,
fig. 2, 3,4.)

BIRDS.

§ 131. The kidneys* of this class (with a few exceptions,
as the cormorant, &c.) form a double row of distinct but con-
nected glandular bodies, placed on both sides of the lumbar
vertebrae, in cavities of the ossa innominata; one of the most
instructive examples of the remarkable analogy between the
structure of the secreting viscera, properly so called, and the

Aloys. Galvani in the Comment. Instit. Bonmiem, torn. v. p. 9, pL508.

ON THE URINARY ORGANS. 133

conglomerate glands.* The urinary bladder is wanting in
the whole class, and the ureters open into the cloaca.i'

AMPHIBIA,

§ 13^. Animals of the genus testudo and rana have an uri-
nary bladder, which is double in many of the frogs, properly
so called. The crocodile, on the contrary, and several true
lizards have none. The same remark applies to the serpents,
in whom the ureters open into the cloaca.:]:

The two large bags, which the author, and also Cuvier {Leqons
(TAnat. comp. tom. v. p. 237) represent as urinary bladders of the
frog and toad, are stated by Townson to have no connexion with the
ureter. Indeed it is very clear that the ureters open at the posterior
part of the rectum, while these two receptacles terminate on the front
of that intestine. (See his Tracts and Observations, p. 66, tab. 3.)
He states that the fluid contained in these reservoirs is a pure water^
The size of these bags, which exceeds all ordinary proportion to the
bulk of the kidney, renders it likewise probable that they are not
receptacles of urine. Either of the bags is at least twenty or thirty
times as large as the kidney.

FISHED.

I 133. The glandulas suprarenales are wanting in this class;
and they seem therefore to be confined to such animals as
breathe with lungs. Although we cannot perceive of what
use an urinary bladder can be to fishes, and animals which
live in water, several genera and species have one.

* See Blumenbach's Elements of Physiology, by Dr. EUiotson, § 470 and 471.

t See Fink De amphibiorum systemate Uropoetico. Hal. 1817. J. Davy, in the
Phil. Trans. 1818, pt. 2, p. 303.

i See Schreiber in Gilbert's Annalen, 1813 ; and J. Davy, in the Phil. Trans,
1821.

134

CHAPTER X.

ON THE EXTERNAL INTEGUMENTS.

^ 134. Among the various objects and functions of the com-
mon integuments, as they are called, one of the most import-
ant, and most general, in red-blooded animals, is the office
which they perform as emunctory organs. Hence we may in-
troduce here with propriety what we have to say on the sub-
ject.

^ 135. The basis of all the other coverings consists in the
proper skin, {cutis vera) which is common to the four classes
of red-blooded animals, and may be regarded as the condensed
external surface of the cellular substance, with nerves, blood-
vessels, and absorbents interwoven in its texture. This is
covered externally by the cuticle, which is very uniform in its
structure, at least in such animals as breathe by means of
lungs. The rete mucosum lies between these; but it can
only be shewn, as a distinct layer of the skin, in warm blooded
animals. Lastly, the cuticle is furnished in the different
classes with peculiar organs for the formation and excre-
tion of particular matters, viz. hairs in mammalm, feathers in
birds.*

The epidermis of the cetacea is quite smooth ; and marked with
none of those lines which are so often seen in the other mammalia.

It is detached from the surface, in the form of small scales, in all
the mammalia, except the whales ; and in some this happens chiefly
at the season when their hair is shed. It gives the skin a branny ap-
pearance.

It is in the rete mucosum that the colour of the skin resides ; but

* See De Blainville Be V Organisation, dei Animaux, ou Prinoipes d' Anatomie com-
par6e, torn. i. Paris, 1822.

ON THE EXTERNAL INTEGUMENTS. 135

this part possesses, in very few instances, any brilliancy of colour
in the mammalia. It is of a beautiful red and violet on the nose and
buttocks of some baboons ; and silvery white on the abdomen of the
celacea. It is remarkably thick on these animals ; being about the
sixteenth of an inch on the back, and such parts as are of a black co-
lour.

The vascular net-work, says De Blainville, in the work referred to
by Blumenbach, which is situated immediately over the cutis, occu-
pying its whole surface, is in general of an exceedingly thin texture ;
it is formed entirely of arterial, venous, and lymphatic vessels, which
undergo many complex ramifications and anastomoses ; this net- work
is spread over the projections situated on the surface of the cutis. The
pigmenium does not perhaps exist in all animals ; it forms at the sur-
face of the vascular net-work a layer more or less defined, of slight
consistence, semi-fluid, and in effect composed entirely of very mi-
nute grains, agglutinated to each other, without any organic conti-
nuity between their own particles or with the other portions of the
skin ; it is a sort of artificial membrane or depository, which is va-
riously coloured, and which seems to be exhaled by the parietes of
the veins. This pigmenium and the vascular net- work are both crossed
by the nervous extremities which meet at the surface of the skin, some-
times under the form of papillae. These two parts of the skin are
those, which, since the time of Malpighi, have been known by the
name of Malpighi's net-work, corpus reticulare, reticulum mucosum, on
account of the sort of net-work which they form for the passage, not
only of the nervous papillae, but also of the accessory parts. They
are both in my opinion, says De Blainville, the source of the colour-
ing matter, and the pigmentum is the depository of that matter.

The colour of the skin is different in the inhabitants of different
countries; in some it is white, in others brown, yellow, red, and
black. This variety depends on something peculiar in the constitu^
tion, and in no way on climate ; it arises just from the same cause as
the difference in the colour of plants and animals. This is proved
by the fact of the Negro and American children being born with the
colour peculiar to the respective races, as well as by the peculiar
organization of the skin. Humboldt says, that the children in Peru,
Quito, on the coast of the Caraccas, on the banks of the Orinoco,
and in Mexico, are never white at the time of birth ; and the Indian
caciques, who are well provided for, and live in houses, are of a
reddish brown, or copper colour, all over the body, with the excep^-
tion of the palm of the hand and sole of the foot. Vid. Rudolphi s
Physiology, by Dunbar Howe, § 43.

MAMMALIA.

§ 136. The cutis of this class varies infinitely in thickness.
It is extremely thin and delicate in the wing of the bat, and on
the contrary exceedingly thick in the rhinoceros, elephant, &c.

136 ON THE EXTERNAL INTEGUMENTS.

also in the web-footed animals, particularly the walrus.* The
form of the papillae on its external sm-face is very various in
the different animals of this class, as, indeed, in different parts
of the same animal. They are sometimes threadlike, as on the
paws of the hear, and are very elegant on the teats of the true
whale [balcBna mysticetus). I have also observed this in se-
veral macacos (simia cynomolgus) and mandrils (papio mai-
mon).

The colour of the rete mucosum varies, even in individuals
of the same species, as in the different races of mankind. It is
thickest in some cetacea.

I have had an opportunity of examining the skin of the ce-
tacea in a halcena boops, and in a dolphin {delpMnus del/phis).
In both the rete mucosum was very thick ; but by no means
equal to the breadth of a finger,^ as is represented in a whale of
uncertain species in the Museum Gaubianum.t

In some spotted domestic animals, particularly the sheep,
rabbit, and dog, there is a remarkable connexion between the
colour of the palate, and even sometimes of the iris, and that
of the skin ; for spots of similar descriptions are found in
both parts4

The cuticle is often of very unequal thickness in particular
parts, from the different purposes to which it is destined.
Thus it is very thin on the points of the fingers in apes and
baboons, when compared with its great thickness where it co-
vers the callosities on which they sit. In various multungida,
particularly the elephant, it forms a kind of horny processes,!
lying close together in several parts of the body. But diffe-

* Hence, the old Normans used to make their almost imperishable cables from the
skin of this animal. See J. Spelman, Vita Mlfridi magni Anglorum Regis, p. 205.
Oxon.

+ See Mus. Gaubian. 1783, p. 14.

t See among other works, Schneider's additions to his German translation of
Monro's Physiology of Fishes,

§ These processes, as I observed them on the proboscis of the elephant, appeared
very similar to the warty cuticle of the two English porcupine-men, whom I saw se-
veral years ago, and which has been well described by W. G. Tilesius, in his Mono-
graph über die beiden sogenanten Stachelsehweinmenschen aus der Familie Lambert.
Altenb.1802.

ON THE EXTERNAL INTEGUMENTSS. 137

reiices of this kind are too numerous to admit of their being all
noticed in this work.

Villi, or papillas of the skin are found on those parts which corres-
pond to the toes and fingers of man. They exist also on the trunk of
the elephant, and on the snout of the mole and pig.

The cutis of mammalia is much thicker on the back than on the
belly.

§ 137. Hairs, at least single ones, are found in all adult
mammalia, even without excepting the cetacea. In various
states of thickness and strength they constitute every inter-
mediate substance, from the finest vv^ool to the strongest quills
of the porcupine. Thick bristles, and hairs, as they are found
for instance in the tail of the elephant and other animals, re-
semble horn, or fish-bones in texture ; while, on the other
hand, both these substances may be easily split into a kind of
bristles. Hairs are commonly cylindrical ; some, however, are
broad with two sharp edges ; as in the toes of the ornithorhyn-
chus and the common porcupine. Others, as the whiskers of
the seal,* are also flat, but have rounded and denticulated
margins, so that they have a kind of knotty, or jointed appear-
ance. Something similar may be observed in the hair of some
cloven-hoofedf animals, and most remarkably in that which
covers the scent-bag of the musk {moschus moschiferus). These
are at the same time filled with a very loose medullary tex-
ture, and consequently very brittle. Some are thick and firm,
but perforated by a narrow tube, which runs through their axis,
as the long stiff whiskers of the phoca ursina. The hairs on
the tau of some species of porcupine are entirely hollow, like
the quill of a feather.

The hair is the most incorruptible part of the body, and

* Albini Annotat. Academ. lib. 3, p. 66.

t In consequence of a degeneration of the formative impulse, which seems to re-
side chiefly in an unnatural formation of the skin, the hair of the human subject
may assume an unusual appearance, similar to that of some quadrupeds, particu-
larly of the goat and deer kind. This was the case with a woman from Triers, who
■wai shewn here, as well as in many parts of Europe, in her seventeenth year. See
Lavater's Physiognom. Fragmente, part 4, p. 68. And the supplement to Buffon,
vol. iv. p. 571.

138 ON THE EXTERNAL INTEGUMENTS.

possesses in great perfection both kinds of reproductive
power; viz. the natural, which takes place in a healthy state,
and the extraordinary, which is exerted after an accidental
loss.* It is electrical in some species, and serves in those ani-
mals which possess much of it, as a mode of excreting super-
fluous phosphoric acid.+

There are secretions from the integuments in some species
of mammalia, manifesting themselves by peculiar smells, which
constitute specific characters in some of the horse and dog-
kind, as completely as the national smell of certain varieties of
the human XB.ce.%

The skin secretes a matter of peculiar odour in some races. " The
Peruvian Indians," says Humboldt, {Political Essay, i. 245) " who in
the middle of the night distinguish the different races by their quick
sense of smell, have found three words to express the odour of the
European, the Indian American, and the Negro ; they call the first
pezuna, the second posco, and the third graco." He adds, " that the
casts of Indian or African blood preserve the odour peculiar to the
cutaneous transpiration of these primitive races."

The following quotation from the 2d chapter of the author's Ma-
nual of Natural History {Handbuch der Naturgeschichte) explains the
terms made use of in the foregoing paragraph, represents the sub-
ject in an interesting point of view, and contains the result of some
curious experiments.

In speaking of the growth of organized bodies, we must notice
their power of reproduction — that wonderful property of restoring
or renewing parts that have been mutilated or entirely lost. This is
one of the wisest provisions of nature for guarding animals and plants
against the numerous dangers by which they are surrounded. HencCj
when viewed in connexion with the system of growth altogether, it
constitutes one of those grand characters which distinguish the ma-
chines that proceed from the hand of the Creator, from all the pro--
ductions of human skill. The springs and wheels of mechanical in-
struments have no power of repairing themselves when injured or
worn ; but such a power, in different degrees, is imparted to every
animal and plant.

At different periods of the year several organized beings lose by a
spontaneous and natural process certain parts of their body, which

* Blumenbach's-MamiaZ of Natural History, by Gore, p» 27.
t FovLVCToy, Systeme. des Connoissances Chirurgiques, vol. ix. p. 270.
X I hava. said more on this subject in the third edition of, my work De Generis
Humani Varietate Nativa, p. 163.

ON THE EXTERNAL INTEGUMENTS. 139

are subsequently renewed. Examples of this occur in the fall of the
stag's horns ; in the moulting of birds ; in the renewal of the cuticle
of serpents, and of the larvae of insects, and that of the shell of the
Crustacea ; the fall of the leaves of trees, &c. This may be called
ordinary or natural reproduction.

The second, or extraordinary kind of reproductive power is that
by which wounds, fractures, or any accidental mutilation or loss of
parts of an organized body are remedied or restored. Man indeed,
and such animals as are nearly allied to him, possess this property in
a very limited degree, while its strength and perfection are truly asto-
nishing in several cold-blooded animals, as the water-newt, the crab
and lobster, snails, earth-worms, (lumhricus terrestris) sea-anemones,
{actinia) the starfish, (asterias) fresh-water polypes, [hydra) &c.

Some experiments on this reproductive power require a hand ex-
ercised in such employments, together with various precautions, and
a favourable combination of circumstances, for their success. Hence
persons must be cautious in concluding against the truth of any state-
ment, because their own experiments do not succeed. After several
fruitless attempts on this subject, I have lately succeeded in observing
the reproduction of the whole head of the snail, (helix pomatia) with its
four horns ; which occupied about six months.

I preserve in spirits a large water- newt, (lacerta palustris) from
■which I extirpated nearly the whole eye several years ago. All the
humours were discharged, and then four-fifths of the emptied coats
were cut away. In the course of ten months an entirely new eye-ball
was formed ; with cornea, iris, crystalline lens, &c. ; and this is only
distinguished from the same organ on the opposite side by being
smaller. See the Gottingen Literary Notices for 1787, pp. 28, 30.

BIRDS.

% 138. The integuments of birds have the same three parts
with those of mammalia. Some are furnished with hair in
particular situations ; as the mdtur barhatus, the raven, and
the turJiey. Others, as the cassowary, have long spines like
fish-bones in their wings, which approach in the tubular struc-
ture of their roots, to the formation of feathers ; the universal
and peculiar covering of this class of animals. The particular
differences in the formation of the feathers are innumerable.*
Among the most remarkable are the small scale-like feathers
{squamulce ciliatce) of the penguin's wing ; and the horny, flat,
and pointed processes on the tip of the neck, and wing-feathers
of the common fowl in its wild state ; and on those of the Bo-

* See Nitzsch's Pterographische Fragmente, in Voigt's Neu. Magazin, ü, p. 393,

140 ON THE EXTERNAL INTEGUMENTS.

hemian chatterer {ampelis garrulus). Several birds in differ-
ent orders have two or more feathers arising from a common
quill.

In a young ostrich, which had just quitted the egg, and which
now lies before me, there are as many as twenty feathers on the
back, proceeding from a single barrel.

In the encysted tumours of the ovaries, large collections of
hair are not unfrequently found, and in the thoracic and abdo-
minal viscera of tame geese and ducks preternatural formations
of feathers, covered over with a kind of fat, are also met with.*

The periodical renewing of the feathery covering, at what
is called the moulting season, takes place in a short space of
time, and comes therefore more under our observation than
the change of the hair in mammalia. This process has afford-
ed a very interesting physiological remark, which has been
often made in several species of those birds in which the male
and female have different plumage; viz. that as the latter
ceases in her old age to lay eggs, she obtains the male plu-
mage.

Lastly, the integuments of birds serve the office of emunc-
tory organs, which is proved even by the process of moulting,
as well as by the separation of peculiar matters from the skin.
Thus the cockatoo, {psittacus cristatus) as well as some other
species of psiitaci, and several birds of different orders, have
a large quantity of white mealy dust discharged from their skin;
particularly at the pairing time.

AMPHIBIA.

§ 139. The very various integuments which are found in
the different orders and genera of this class, consisting of
shields, rings, scales, or simple skin, are covered externally
with cuticle, which is frequently separated in many of these
animals, as in the snake, forming what is called snakes-shirt
{leberis, senecta) and water-newt.

* Similar cases are mentioned in Harrow's Seltenheiten, b. i. s. 255. Penada
Osservaz. e memorie Anatomi Pad, 1800 ; and Otto Seltenen Beobachtungen zur Ana-
tomie. Bresl. 1816.

ON THE EXTERNAL INTEGUMENTS. 14t

The process of separation is repeated every week for some
time in the latter animal, particularly in spring and autumn.
Some, which have small fine scales, as the chameleon, or a sim-
ple skin, as some /"rog-*, change their colour occasionally, either
from difference in the light or warmth, or from the effect of
their passions.

The skin of the frog and toad does not adhere to the subjacent
parts, as in other animals, but is attached to them only at a few
points, and is tinconnected elsewhere ; so that it may be compared to '
a bag containing the animal.

The reflection of coloured objects on the glittering scales of the
chameleon, probably gave origin to the fable that its colour is regu-
lated by that of the bodies near which it is placed.

FISHES.

§ 140. AH fishes, without exception, are covered with
scales, which are bare in those which inhabit the open sea,
but on the contrary are covered with a mucous membrane in
those which live on coasts, or in fresh water. It is remark-
able that the colour of the skin in some fishes, as for instance,
the mullet, {mullus barbatus) depends on that of the liver.*
The scales are not changed like hair and feathers, but are pe-
rennial ; and are said to receive yearly an additional layer to
their laminated texture, from the number of which the age of
the animal may consequently be determined.

The lower orders possess in general an epidermis. In the testacea
it usually covers the surface of the shell, and obscures the brilliancy
of that part until it is removed. It may be seen by plunging a snail-
shell into boiling water. It is very thick and villous in some species,
as in the urea pilosa.

Crustacea have it ; also insects, both in their perfect and larva
states. It is shed in the lattei several times before the change to the
state of chrysalis ; seven times in most of the butteifiies and bom-
hyces.

It is very distinct in the vermes, as in the common earthworm and
leech, which often shed it. In the sipunculus saccatus it is loose and
not adherent to the surface.

Hairs are formed in small bulbous bodies implanted in the true
skin, and grow from their base.

• Santorini Ob(. Anatom. Venet. 1724, vol. iv. p. 4.

142 ON THE EXTERNAL INTEGUMENTS,

If one of the large hairs, which grow on particular parts of some
animals be examined with glasses, its surface appears grooved, as if
it were composed of several filaments ; and one or two canals are
discovered in the substance of the hair, containing a kind of fluid,
which has been called the medulla.

In the hedgehog, porcupine, &c. these filaments are covered with a
layer of horny substance ; and the cavity is filled with a white spongy
matter.

The colour of the hair is influenced in great measure by that of the
rete mucosum, and this circumstance is particularly observable in the
human subject. Its texture is much modified by climate and mode
of life. The dog in Siberia, and the sheep in Iceland, are covered
with a kind of long and stiff" hairs, while the same animals, in very
hot countries, as in Guinea, lose this covering altogether. A species
of goat furnishes the long and silky hair which is manufactured into
the valuable shawls of Cashmere. The cat, rabbit, and goat, are co-
vered with a very long and peculiar kind of hair in Angora, a small
district of Asia Minor, and the superior qualities of the Spanish wool
are well known.

This seems to be the proper place for considering, in a cursory
manner, the other insensible parts, which are found on the surface of
the body.

The horns of the mammalia are generally formed on processes of
the frontal bone, which they cover in the manner of a sheath, as a
glove does the finger. They consist of a solid, insensible, and elastic
substance, which in many cases has a fibrous appearance, as if it were
composed of an aggregation of hairs. This structure is most parti-
cularly remarkable in the rhinoceros, where the horn is solid, and
situated over the nasal bone. The fibres analogous to hairs are very
distinct, and are observable at the base of the horn, detached from
its substance in the form of bristles. The mass of the horn is entirely
pervaded by innumerable pores.

In those animals which have a long process within the horn, the os
frontis begins to form a tubercle, about the seventh month of concep-
tion. This being gradually elongated, elevates the integuments, which
become callous, and harden as the horn is lengthened. Between the
bone and the latter part a soft vascular substance is interposed, from
which the horn is produced by means of successive additions to its
base and internal surface.

The nails and claivs of animals are formed just like horns, they co-
ver a process of the last phalanx, which is analogous to the frontal
process of the horn, and grow from the root or base, to which the in-
teguments are attached, while they wear away at the loose edge.

The hoof of the horse, ass, &c. is a horny covering of the last pha-
lanx ; similar, in its structure and formation, to the parts just men-
tioned, but including the whole of the bone. Its internal surface, in
the horse, is formed into avast number of thin plates, which are
placed alternately with corresponding laminae of the vascular sub-
stance, and constitute a most close connexion between the two parts.

ON THE EXTERNAL INTEGUMENTS. 143

This union is so firm, that, when the inferior portion of the hoof has
been removed, a horse may be trotted roughly without the foot being
separated from the upper part of the hoof.

The body of a bird which has just quitted the egg is covered with
hair instead of feathers. Fasciculi of hairs are produced from one
common bulb, which is the rudiment of the future feather. In a few
days a black cylinder appears, which opens at its extremity, and
gives passage to the feather. The opposite end receives those blood-
vessels, which supply the vascular substance in the barrel of the fea-
ther ; when the stalk of the feather has received its complete growth
this vascular body is dried up, and presents the well-known appear-
ance in the barrel of quills.

The parts which have just been described, as well as the epidermis,
and the scales, or rather hard coverings of reptiles and fishes, possess
neither vessels nor nerves ; and therefore the whole superficies of an
animal's body is really insensible, and constitutes a dead medium,
through which impressions are conveyed to the subjacent living parts.

^

144

CHAPTER XL

ON SEVERAL PECULIAR SECRETIONS.

§ 141. It is necessary that we should take notice of some
organs destined for the secretion of peculiar fluids, the use of
which is not hitherto sufficiently determined. These occur
in particular classes, or in certain genera and species of ani-
mals, and may be most conveniently considered here, at the
end of that division which treats of the natural functions.*

MAMMALIA.

§ 142. Besides the well-known salivary glands, there is an-
other, which has been described by Nuck in the orbit, par-
ticularly of the dog, and some other predacious animals, which
has an excretory duct opening near the last tooth of the up-
per jaw.-j- Professor Jacobson J has described a remarkable
secreting gland, which is situated in man and in many other
mammalia, and probably in all birds, on the external side of
the nostrils, the excretory duct of which opens at the anterior
extremity of the lower concha. He names this organ after its
illustrious discoverer, la glande nasale de Stenonis. §

§ 143. Both sexes of both species of the elephant, viz.
the African and Indian, have a considerable gland j| at the
temple, between the eye and meatus auditorius, secreting in the
rutting season a brownish juice, which is discharged through
an opening in the skin.?

* See Tiedemann, in Meckel's Archives, vol. ii. p. 112.

t Nuck, Sialogi-aphia, tab. 3 and 6.

X Bulletiti des Sciences de la Socitte philomatique, for April, 1813.

§ Stenonis Observat. Anatomie, 1662, vol. xii. p. 105. Analyse des travaiuc de
la Sociitä Veterinaire de Copenhague, 2 Report, 1815, 4; and Nitzsch, in Meckel's
Archives, vol. vi. p. 234-269.

11 See the Histoire des Animaux of the Parisian academicians, part 3, p. 138 ; and
Camper's plates on the anatomy of the elephant, tab. 10, 11.

% This circumstance has been remarked of old, and has been noticed in the

ON SEVERAL PECULIAR SECRETIONS. 145

As far as regards the structure of the organ, this secretion
resembles most that of the gland placed at the back of the
Mexican musk-hog, or pecari (sus tajafu).

This remarkable gland is found on the back of the animal, over
the sacrum. It is of a considerable size, (between two and three
inches long, and above an inch broad) and is composed of several
lobules, whose ducts join into one canal, which penetrates the skin.
It furnishes a secretion of a very pleasant musk-like odour, from
which Tyson denominated the animal aper moschiferus. The opening
of this part on the back has been described by many authors as the
navel. (Bartholin. Cent. 2, Hist. Med. 96.)

Tyson in the Philos. Trans. No. 153, or in his works, London, 4to.
1751, with a good delineation of the gland.

§ 144. Several ruminating bisulca, and the hare, have on
the outer side of the upper jaw, near the ossa nasi, sebaceous
sinuses, which have received that name from the adipose and
viscous substance which is separated there in great abun-
dance in some animals, and which is well known in the stagj
where it is supposed to be of a lacrymal nature.*

§ 145. In most of the ruminating animals, and in the haret
there are cavities in the groins, near the genitals, called by
Pallas antra inguinalia, and containing a strong-scented seba-
ceous substance secreted from glands which lie under the in-
teguments.t

§ 146. Some other mammalia have pouches on the abdo-
men, covered internally with a fine hair, and containing fatty
secretions of peculiar odours. Of this kind are the bags near
the anus of the badger,% and that which contains the teats of
the female marsupial animals.§

Indian Mythology. See Wilford, in the Asiatic Researches, vol. iii. p. 443 ; it is
noticed also in Strabo. Compare Beaulieu, Voyage mix Indes OrientaleS) p. 105, (in
the collection of Thevenot the elder, vol. ii.), Jv W. Heydt's Ostind. Schauplati ;
and particularly A. W. Schlegel's Indische Bibliothek, p. 165.

* Vide Ph. Seifert Spicilegia Adenologica. Berol. 1823, 4, p. 13, tab. 3.

Y. Y. Wepfer, in E. N. C. Dec. 11, a. b. Obs. 118.

Chabert and Heron, in the Journal de l'Agricultui-e, &c. May, 1778, p. 87.

f Wepfer in the same collection, Dec. I. A. 3, Ohs. 167.

I J. Gottl. Walter, in the M^moires de I' Ac, des Sc. de Berlin, 1792.

^ The yellow matter contained in this pouch was compared by Tyson with that
which in secreted in the axilla of the human subject. Phil. Trans, vol. xx. p. 120.

L

146 ON SEVERAL PECULIAR SECRETIONS.

§ 147. There are also, in the badger and the opossum, as
well as in several other carnivorous animals, (both among the
digitata and palmata,) pecuUar glands and bags at the end of
the rectum, secreting a yellow substance of a strong and disa-
greeable smell in its recent state, and which frequently gives
to their excrement a kind of musk-like odour.*

These anal bags are of a spherical form, and have a small round
opening just at the margin of the anus. They seem to belong parti-
cularly to the carnivorous animals. They may be seen very well in
the cat. Their secretion possesses that strong disagreeable odour
which characterizes so remarkably many animals of this order, as the
fox and all the weasel tribe, and which has even made the polecat
proverbial in common language, and has bestowed on it its scientific
name, mustela putorius. Some American species exceed the fetor
even of the polecat. This is the case with the viverra mephitica and
coasse (the skunk and squash). They pour out the fetid matter when
pursued ; and are thereby effectually defended, as neither man nor
animal can approach them.

These parts are not, however, confined to the Carnivora, as several
rodentia possess them,

§ 148. These anal glands must be distinguished from ano-
ther kind of similar glands and bags, which also secrete
strong-scented matters, but seem to be rather connected with
the genitals.-f- These are found in some of the same carnivo-
rous animals which possess the anal glands, as the lion, the
civette, &c. ; also in many herbivora, which want the latter or-
gans ; in some of whom they exist in both sexes, as in the
beaver,% the ondatra,^ {mus ssibethicus) &c. ; in others they
are peculiar to the male, as in the musk animal, |j whose pouch
is found in the prepuce near the navel.

* See Grew, Museum Regalis Societ. tab. 23, where he represents these bags in the
polecat, weasel, fox, and cat, Daubenton, torn, ix, tab. 4, in the lion, tab. 16, in
the panther, tab. 33, in the civette, torn. yii. tab. 13, in the otter. Mitchell, in the
American Museum, vol. v. p. 487. t

t Tyson, who first carefully examined the different kinds of what he calls scent
bags, has not distinguished them from each other. See Plot's Natural History of
Oxfordshire, p. 305; and the Phil. Trans, vol. xiii. and xx. ; also Haller, Elem.
Physiol, torn. vii. p. 147, &c.

t Daubenton, tom. viii. tab. 41, 42.

$ Sarrazin, in the Me'm. de VAcad. des Sei. 1725, tab. 12, 13.

\\ Vsil&SiSpicileg.. Zoolog. \d, tab. 6.

ON SEVERAL PECULIAR SECRETIONS. 147

It is from these glands, and not from the testicles, as naturalists
have absm'dly supposed, that the substance called castoreum is pro-
duced. A delineation of the parts, from the dissection of the Pari-
sian academicians, may be seen in the collection of Blasius. Anatom.
Animalium. tab. 13.

That valuable article of the materia medica, musk, is produced
from similar glands in the moschus ?noschifer, (the musk) an animal
found in the mountains of Thibet, and the southern parts of Si-
-beria.

§ 149. We must also mention here the glandular cavities,
covered internally with hair, which ai"e found in the feet of
several ruminating bisidca, and particularly in the sheep.
They have an excretory duct opening at the junction of the
toes ;*" and the obstruction of this, pai'ticularly from a long
continuation of wet weather, occasions troublesome symptoms.

BIRDS.

§ 150. Although birds do not masticate their food, several
of them, particularly among the pici, have considerable sali-
vary glands f at the sides of the lower mandible. The secre-
tion of these glands serves to facilitate the numerous and
strong motions performed by the tongue in deglutition.

The pancreas is of considerable size, particularly in those
birds of prey which do not drink; its form and structure
vary considerably.

It has been already stated that salivary glands, in the proper
sense of the term, do not exist in birds, and that the parts which
the author mentions here must be regarded in a different point of
view.

§ 151. The glands which secrete the oil, on the upper part
of the tail, are largest in aquatic birds ; in some of which, as
the anas moschata, the secreted substance has a musk-like
odour. In that race of the common-fowl, which has no tail,
{the gallus ecaudatus) this organ no longer exists.;]!

* R. Livingstone, in the 2d vol. of the Society nf New York, p. 140. J. F.
Neimann, in his Taschenbuch für Hauslhierürzte, vol. ii. s. 87.
t V. A. Huber T)e Lingua J'ici viridis,
t Reaumur, Art de faire (.dorre les Oiseaux Domesti^nes, torn, ii. p. 332.

148 ON SEVERAL PECULIAR SECRETIONS.

AMPHIBIA.

§ 152. I do not think it probable that the part which has
often been considered as a pancreas in this and the following
classes of animals, really deserves that name. Zootomists
have not been able to agree on this point ; Charas took that to
be the pancras of serpents, which Tyson with the ancients
called the spleen.

Anal glands, which disseminate a strong specific odour at
certain times are found in some animals of this class; for
instance in the cayman, (lacerta alligator) and the rattle-
shake.*

§ 153. An acrid fluid exudes through numerous pores of
the skin in some reptiles, when they are irritated ; as in the
salamander and in toads. It is said that the gecko secretes a
really venomous fluid between its toes. But there is a much
more dangerous kind of poison formed in some serpents,
which are distinguished from the innocent ones by the organs
pointed out in a former part of this work.t

There is found in the crocodile, on each side of the lower jaw,
and just under the skin, a gland, whose duct opens externally. It
secretes a substance smelling like musk.

There are situated on the heads of most serpents five pairs of
glands ; the first is a small, long, round, and very hard gland, si-
tuated at a very little distance from the skin, close behind the ante-
rior extremity of the lower surface of the mouth. These may un-
doubtedly be compared to the sub-lingual glands of other animals.
Cuvier has found them in the amphisbcence, where they are in propor-
tion the largest ; but neither he nor any other author mentions their
existence in the other species, although with the exception of the
typhlops, I found them in all the species which I examined.

The second is situated more behind, and to the inner side of the
eye : in general it is of a considerable size, and of a white soft colour.
Meckel found them in the aniphisbasna alba and fuliginosa ; also in
the eryxjaculus, tortrix ocytale, elaps, they are very considerable. They
are generally situated without and behind the orbit, particularly in

* Tyson, in the Philos, Trans, vol. xiii. p. 38.

+ On the peculiar poison-glands in the coluber (trigonocephalus) mutus and berus,
see Seifert, p. 3, tab. 1, fig. 1, 4; on the salivary glands of serpents, see Tiede-
mann, in the Denkschriften den' Akad. der W. zu München für, 1813 j and on some
other secreting organ in the orbitar region of many poisonous serpents, see P. Rüssel
and Home in the Phil. Trans, for 1804.

ON SEVERAL PECULIAR SECRETIONS. 149

the coluber, tortrix, and eryx, but in the boa, python, and poisonous
serpents, part of the gland Hes within the orbit.

The third, which is not so common as the two preceding, is a
gland of some length, and situated close to the rami of the lower
jaw ; there are numerous excretory ducts, which open externally
through the teeth of the lower jaw, in a simple longitudinal row.
Cuvier has described them in the coluber and boa ; afterwards Tiede-
mann and Cloquet gave delineations of them as they are found in the
coluber natrix, and Rudolphi as they are found in the vipera vera ;
they have since been found in several other species of serpents. They
correspond in their form, structure, and situation, 'to the buccal and
labial glands of mammalia.

The fourth is situated externally, close to each side of the upper
jaw. In the vipera dubia Meckel found a small gland at the corner
of the mouth ; Tiedemann found them in the unguis, although Meckel
who examined three fine specimens was not able to detect them. In
the coluber, a?nphisbcEna, tortrix, and eryx, this gland is very consider-
able ; in the pytlion, crotalus, vipera vera, they are of moderate size ; in
the elaps they are extraordinarily small, and intimately connected
with the excretory ducts of the poisonous glands situated beneath them.

The fifth are the poison-glands : these are the most remarkable,
and it is difficult to conceive how they could have been overlooked
by the earlier anatomists. They are situated above the upper jaw,
behind and below the eyes ; they are surrounded by a very strong
muscle, and in fact embedded in it, so that they cannot be seen until
the muscle has been divided. They are of some length, and have a
laminated texture ; internally they have a considerable cavity, and
are distinguished from all the other glands by a very long excretory
duct which takes its course along the outer surface of the upper jaw,
and opens above and before the poison teeth in such a manner into
the sheath, that the poison flows into the upper opening of the tooth.

Meckel has come to the following conclusions on the number and
proportional size of the glands of serpents.

1. Several poisonous serpents, viz, the crotalus, naja, vipera vera,
elaps lemniscatvs, possess the greatest number of glands ; for, in ad-
dition to the poison and salivary ones, they also have five pairs.

2. Four pairs only exist : 1, in the vipera dubia, for besides the
poison glands, they have merely the lachrymal and lingual, and a
slight rudiment of the labial at the angle of the mouth ; and 2, in the
coluber python, amphisbana, there are also only four pairs.

3. The anguis fragilis has four pairs, the upper labial glands only
being wanting ; but in the trigonocephalus both pairs of the labial
glands are wanting.

4. Lastly, in the typhlops crocotalus, all or nearly all are wanting.

5. Those serpents which have no poison glands possess all the
others in a greater state of development. Both the poison and other
glands have excretory ducts. Vid. Meckel's Archiv, fur Physiologie,
Lip. 182G.

150 ON SEVERAL PECULIAR SECRETIOKS.

FISHES. . .

§ 154. The most universal secretion in this class, which
comes under the present chapter, is that of the mucus, which
besmears their skin and scales, and which is formed in canals*
lying near the lateral lines, and in the same direction with
them ; one or more of these canals running on each side from
the head to the tail-fin. In some fishes the mucus is poured
out in the intervals of the scales ; but in others those parts
are perforated by regular openings for its discharge.-f-

Cuvier represents the tubes which open in the course of the linea,
lateralis of fishes, as the excretory ducts of two glands placed above
the orbits. {Legons (VAnat. comparee, torn. v. p. 260.)

In the skate the openings are not confined to any particular part,
but are scattered over the surface. The tubes radiate from one
point, just above the angle of the jaw ; and the third branch of the
fifth pair of nerves is distributed at that part ; its filaments accom-
panying the tubes.

For an account of the electrical organs of fishes, which must be
considered as parts secreting the electrical matter, see § 218 ; and
for their swimming bladder, in which a secretion of air is effected,
§187.

INSECTS.

§ 155. There are no true conglomerate glands, nor analo-
gous parts in insects ; but their different secretions are per-
formed by loose vessels.:]: Besides the different secretions
of peculiar matters, which belong exclusively to single species,
as the vapour, which some carabi (carabus crepitans, margi-
natus, &c.) discharge, and the strong odours with which seve-
ral of the bug-kind defend themselves in case of necessity,

* Professor Jacobson, after a careful examination, is of opinion, that these ducts
in the cartilaginous fishes may be regarded as organs of a peculiar sense, Nouveau
Bulletin des Sciences pour la Soc. Philomatique, 1813.

On the curious structure of the numerous canals on the head of several species
of the ray and shark, see Stenon, who has the merit of having discovered them, in his
classical M'ork, De Musculis et Glandulis, p. 42 ; and Elementor. Myolog. Specimen,
p. 72 ; also the recent work of Lorenzini, sulle Torpedini, pp. 7 and 21.

t A. Q. Rivinus, in the Leipsic Acta Eruditorum, 1687, p. 161 ; and Perrault
Essais de Physique, tom. iii. tab. 20.

t Cuvier, in the MSmoires de la Soci^te d'Hist, Nat. de Paris, an 7, p. 40.

ON SEVERAL PECULIAR SECRETIONS. 151

two kinds of secreted fluid deserve to be particularly remarked
in this class : the silk which is formed by the larvae of pha-
lenae* (moths) and by spiders ;*t' and the poison with which
several hymenopterous | and apterous § insects are armed.

The wax, which is prepared by the honey-bees, and by the
Indian coccus mellißcus, deserves to be enumerated among the
secretions which are peculiar to animals of this class.

Almost all the larvae or caterpillars spin for themselves some kind
of covering before their metamorphosis ; but it is the silkworm only
(bombyx mori) that furnishes the materials of our various silk manu-
factures, as the thread which it forms is very pliant and abundant,
and can be easily unrolled.

The secretory organs, which furnish this matter of silk, are the
same in all larvae. They consist of two long tubes, at first small
and tortuous, but growing gradually larger to form a kind of reser-
voir, and terminating in a single very small tube, which opens under
tlae lower lip. It is by moving its head from side to side that the
animal draws out the silk.

In those insects which possess stings, the irritating or poisonous
fluid is formed in a peculiar bag, which sends a duct to the sting.
The latter part is hollow, and its tube opens externally. It is con-
tained in a sheath, and barbed at the sides of its point, so that it
usually remains in the wound which it inflicts. A delineation of these
parts in a magnified view may be seen in Swammerdam, tab. 27 of
the English translation.

VERMES.

§ 156. The most remarkable secretions in this class take
place in the testacea. There is one of these common to the
whole class ; viz. the formation of the calcareous matter of
their shells, 1| which takes place in a peculiar viscus lying near
the heart (sacculus calcarius, Swammerd. glandula testaceay
Poli). The celebrated purple 5[ colour is formed in some ma-

* See Lyoaet, tab 5 and 14.

t Rösel, torn. iv. tab. 29.

X See Swammerdam's plates of the organ in the bee, tab. 18 and 19.

$ Rich. Mead Oj)era. Medica, torn. ii. tab. 3.

II Swammerdam, tab. 5, of the Helix Pomatia. Poli, torn. ii. tab. 20, of the
Venus Chione ; tab. 26, of the Area Pilosa. Dr. Wohnlich De lielice Pomatia.
Wirceb. 1813, p. 23 ; and Prof. Jacobson, in Meckel's Archives, vol. vi. s. 370.

f See Ström, of the Buccinum Lajnllus, in the Ilth vol. of Kiobenh. Selsk,
Shrifter, p. 30,

152 ON SEVERAL PECULIAR SECRETIONS.

rine genera; as the buccinum lapillus and echinophorunii
murex brandaris and trunculus, helix ianthina, area nucletis,
&c. Lastly, some bivalves, under extraordinary circumstances,
form pearls * on the inner surface of their shell.

Several acephalous mollusca produce a kind of silk, similar to that
of the larvae of insects. It is sometimes called the beard ; and is
employed by the animal in order to attach itself to rocks, &c. It is
formed by a conglomerate gland, placed near the foot, which latter
part draws out the silk from the excretory duct, and moulds it in a
groove on its surface. The sea muscle, {?nyt/lus) the pinna, and
perna, exemplify this structure. The pinna produces it in such
quantity, and of such quality, as to admit of its being manufactured
into gloves, which is done at Messina and Palermo. (Blumenb.
Handbuch der Naturgeschichte, ed. 6, p. 438.)

The black inky fluid of the cuttle-fish, which has often been sup-
posed to be the bile, is a very singular secretion, that must be noticed
in this place. The bag in which it is contained has a fine callous
internal surface, and its excretory duct opens near the anus. The
fluid itself is thick, but miscible with water to such a degree, that a
very small quantity will colour a vast bulk of water ; and the animal
employs it in this way to elude the pursuit of its enemies. Accord-
ing to Cuvier, the Indian ink, which comes from China, is made of
this fluid. (Legons d'Anat. comp. tom. v. p. 262.)

* Poli, tom, i. IntroductioD, p. 19.

THE VITAL FUNCTIONS.

THE VITAL FUNCTIONS.

CHAPTER XII.

ON THE HEART AND BLOOD-VESSELS.

§ 157. A PERFECT circulating system, to which on the one
hand fluids are brought by the absorbents, to be converted
into blood ; and from which, on the other hand, various juices
are separated in glands, and viscera of a glandular strueturCj
appears to belong universally and exclusively to red-blooded
animals. A pericardium exists in all these animals. Parts of
such a system, particularly a heart, and certain vessels con-
nected with it, are found in some genera of the two white-
blooded classes. It is surprising that so many good anato-
mists, among whom are Blasius, Peyer, Harder, and Tozzetti,
should have denied the existence of a pericardium in the
hedgehog. The membrane is indeed very delicate in this
animal, and it requires some care to avoid tearing it in opening
the chest.

MAMMALIA.

§ 158. The internal structure of the heart is the same as in
man ; but its situation in quadrupeds and cetacea differs from
that which it has in the human subject. It is in the former
situated more longitudinally with respect to the body, resting
rather on the sternum than on the diaphragm. Hence the
pericardium of these animals, with a few exceptions, is not
connected with the diaphragm* as in the human subject; the

* See Morgagni, in his E^U Anat. p. 302, edit. 1764.

156 ON THE HEART AND BLOOD-VESSELS.

portion of the inferior vena cava within the chest is propor-

tionably longer.

t
The heart of the orang-outang is placed obliquely, like that of the
human subject ; but in other simicß the apex only is a little inclined
to the left, and just touches the diaphragm.

§ 159. The larger adult hisulca and the pig have two small
flat bones, (which have been called, particularly in the stag,
bones of the heart) where the aorta arises from the left ven-
tricle. The common notion, that they serve as a support to
the valves,* does not much elucidate the subject.

The right auricle receives in the porcupine and elephant two ante-
rior venae cavae ; the left of which opens near the communication
with the ventricle.

§ 160. It has been supposed that the amphibious animals
of this class and the cetacea have an open foramen ovale, like
that of the foetus, in their septum auricularum. And the ne-
cessity of such an opening has been inferred from their way
of life ; since they often pass a considerable time under water
without breathing. This supposition has been fully refuted
by the repeated dissection of adult animals of this kind, which
has shewn that an exception from the general rule very rarely
occurs.

I possess a very singular heart of an adult seal, the foramen
ovale and ductus arteriosus of which are completely open.
Both the arterial trunks, and particularly the aorta, form
large, and as it were aneurismatic expansions.-f"

In several genera and species of web-footed mammalia, and
cetacea (that is, in the common and sea otters, in the dolphin,
&c.) particular vessels have been observed to be considerably
and constantly enlarged, and tortuous. This structure has
been principally remarked in the inferior vena cava ; where

* C. I. Kench&n, De Ossiculia e Cordibus Animalium. Groning. 1772, 4. Luthii
Observ. Zootomiee, Tubing. 1814. Jaeger, in Meckel's Archives, s. 113 ; and
Leuckart, vol. vi. s. 136.

t The same fact was observed by Seger, in the latter vessel in the seal, of which
he has given an account in the Epftem. Nat. Curios, Dec. 1, an 9, p. 252,

ON THE HEART AND BLOOD-VESSELS. 157

there can be no doubt that it serves, while the animal is under
water, to receive a part of the returning blood, and to retain
it until respiration can be again performed, and the lesser*
circulation be thereby again put in action.

The question, whether or no the foramen ovale be open in such
animals as have the power of diving, and remaining for some time
under vi^ater, seems to be as yet not completely decided. In addition
to the affirmation of the author the evidence of Cuvier may be
quoted ; he states that in several porpoises, in a dolphin and a seal,
he found this opening closed. {Leqons d'Anat. camp. torn. iv. p. 201.)
The Parisian dissectors also found it closed in a beaver. {Description
Anatom, d'tin castor, &c. p. 68.) It has been found perfectly shut in
a porpo/ss and young seal; and according to Sir Everard Home,
(Phil. Trans. 1802) it is closed in the omithorhynchus. On the other
side of the question, besides the fact mentioned by Blumenbach,
which is very striking, we may adduce Sir Everard Home's authority
for the existence of the foramen ovale in an open state in the sea
otter. He found it so in two instances, one of which was in an adult
animal; but the ductus arteriosus was closed. {Philos. Trans. 1786,
pt. 2.) This may perhaps be nothing more than a casual occur-
rence ; as a small opening is not unfrequently found in the human
subject, where no symptom of disease, or defect in the circulating
system has existed,

§ 161. There are some remarkable circumstances in the dis-
tribution of particular arteries in certain animals of this class.
We may notice, as the most singular of these, the rete mirabile,
formed by the internal carotid at its entrance into the cranium,
in several ruminating bisulca f and carnivorous animals ; and
that division of the arterial trunks of the extremities, which
has been observed by Sir A. Carlisle J in the slow-moving ani-
mals, viz. the sloths and lemur tardigradus. The arteries of
the arm and thigh in these cases divide, as they leave the
trunk, into numerous parallel branches, which are united again
towards the elbow and knee. The most curious and elegant
distribution of veins occurs in the foot of the horse ; where
these vessels run in innumerable parallel branches on the an-

* Kalmus, in the Acta Acad. Natur. Curios, torn. i. p. 25.

t It is represented by Monro in the slink mlf. Ohs. nn the Xervon$ S}jstem, tab.
I.

I In the Fhitof. Trans, for 1800, p. 98.

158 ON THE HEART AND BLOOD-VESSELS.

tenor surface of the coffin bone, and form a reticular plexus
of anastomoses on the under part which completely covers the
surface of the bone.

Plexuses or convolutions of the arteries are found in some parts of
the cetacea ; as in the intercostal arteries, in the branches which go
from the subclavian to the chest, and in those which supply the me-
dulla spinalis and the eye. Hunter in the Philos. Trans. 1789, pt. 2.

BIRDS.

§ 162. The whole of this class, without exception, possess
a very remarkable peculiarity in the structure of the heart.
The right ventricle, instead of having a membranous valve,
(such as is found in both ventricles of mammalia, and also in
the left of birds) is provided with a strong, tense, and nearly
triangular muscle. This singular structure assists in driving
the blood with greater force from the right side of the heart
into the lungs : since the expansion of the latter organs by
respiration, which facilitates the transmission of the carbo-
nated blood in mammalia, does not take place in birds, on
account of the connexion which their lungs have with the nu-
merous air-cells, which will be afterwards described.*

§ 168. To this class, and also to those of amphibia and
fishes. Professor Jacobson ascribes a peculiar venous system,
by which the blood is carried from the posterior extremities
and from the sexual organs, not, as in mammalia, to the pos-
terior vena cava, but to the kidneys, or to the kidneys and
liver, for the purpose, as it should seem, of secreting the urine
in these three classes.'|-

AMPHIBIA.

§ 164. The frogs, lizards, and serpents, of this country at
least, (Germany) have a simple heart, consisting of a single

* I have entered more largely into this subject, in the Comment. Reg, Soc. Scient.
Getting, vol. ix. where there is also a representation of the muscle in the heron, p.
128.

t See the Bulletin de la Soc. Philom. 1813. Meckel's Archives, vol. iii. s. 147 ;
and De Systemate venoso pecuUari. Hafn. 1821.

ON THE HEART AND BLOOD-VESSELS. 159

ventricle and auricle.* In others, as for instance crocodiles
and lizards, properly so called, and serpents, the heart con-
sists of one ventricle with two auricles.

The account which Cuvier gives of the anatomy of the heart in the
amphibia, does not exactly accord with that of the author. Cuvier
describes and deHneates the heart of the crocodile as being formed
nearly like that of the turtle (tom. 5, pi. 45) ; he says that the iguana
has a similar structure, and that it obtains likewise in the serpents
(tom. V. p. 221-225). He does not mention the more simple form as
existing in any lizard or serpent.

§ 165. The structure of this part is very different in the
turtle ; and has given rise to more controversy than that of
any order of animals. The heart of this animal possesses two
auricles, which are separated by a complete septum, like those
of warm-blooded animals, and receive their blood in the same
manner as in those animals ; viz, the two vense cavas terminate
in the right auricle, the pulmonary veins in the left. Each
pours its blood into the corresponding ventricle, of which ca-
vities there are two ; thus the structure of the heart hitherto
resembles that of mammalia.

A remarkable difference exists in the structure of the auri-
cles between the testudo caretta and mydas, both of whose
hearts now lie before me. The auricles of the former are thin,
like those of warm-blooded animals ; in the latter they are
very firm, and have almost as thick and strong parietes as the
ventricles.

The characteristic peculiarities which distinguish the heart
of these animals consist in three circumstances. First, the
two ventricles (and in some species of turtles^ the cavities of
the auricles) are extremely small and narrow, but the fleshy
walls of this viscus are of a thick and spongy texture, so that
the heart has the appearance not so much of a double visceral
sac, as of a sponge soaked with blood. Secondly, both the
ventricles communicate with each other ; there is a muscular,
and as it were tubular valve, going from the left to the right

* RwamiDcrdam gives the clearest representatic n of the heart of the frog, ;ind of
tlic vpftsels wliich are most immodiately connected with it, tab. 49.

160 ON THE HEART AND BLOOD-VESSELS.

cavity, by means of which the former opens into the latter.
Thirdly, the large arterial trunks arise all together from the
right ventricle only ; no vessel coming from the left. The
aorta, with its three principal branches,* is situated towards
the right side and the upper part; the pulmonary artery
comes as it were from a particular dilatation of the right ven-
tricle,t which is not situated nearly in the middle of the basis
of the heart ; (it must be understood, as we have already ob-
served, that we apply these terms according to the horizontal
position of the animal).

We can now comprehend how this wonderful and anoma-
lous structure, by which all the blood is propelled from the
right ventricle only, is accommodated to the peculiar way of
life of the animal, which subjects it frequently to remaining
for a long time under water. For the greater circulation is
so far independent of that which goes through the lungs, that
it can proceed while the animal is under water, and thereby
prevented from respiring, although the latter is impeded. In
warm-blooded animals, on the contrary, no blood can enter
the aorta, which has not previously passed through the lungs
into the left ventricle; and hence an obstruction of respiration
most immediately influences the greater circulation.

The best and most intelligible delineations of the turtle's
heart are those given by Mery ;J although he made an errone-

* Two of these go to the abdomen ; the right is the proper aorta abdominalis ; the
left is the ductus communicativus of Mery, who compared it to the ductus arteriosus
of the foetus.

f Mery and Morgagni considered this dilatation as a third ventricle, ventriculus
intermedins ; hence it has happened, that some zootomists have ascribed to the turtle
a single ventricle, (on account of the communication) ; some two, and others three.

i Mtm. de I' Acad, des Sc. 1703. See also Morgagni's excellent account of the
heart of the tortoise, in his Advei-s. Anat. V. A7nmalium, from which he draws the
following correct inferences. Qu(b cum ita sijit. agnovi facile, sanguinem turn ab
universo corpore, tum a pulmonibus redeuntem, ilium quidem per auriculam dexteram
immediate, hunc vero per sinistrum, subjectumque sinistrum ventriculum, omnem deni-
que in dextrum compelli, ut ab hoc, et communicante intermedio turn in cmyus Univer-
sum, tum in pulmones propellatur. ' From these circumstances I ascertained that the
blood which returns from the whole body, as well as that which returns from tiie
lungs (the former immediately by the right auricle, and the latter by the left auri-

ON THE HEART AND BLOOD-VESSELS. 161

GUS application of them to the course which he supposed the
blood to take in the heart of the human foetus. I conclude
from a comparison with my own preparations, that his draw-
ings were taken from the testudo caretta.

The natural structure of the hearts of these animals has a
striking analogy with the unnatural condition of this organ in
persons born with the morbus cceruleus. This phenomenon
with many others tends to shew that certain organs of the human
embryo, as well as the whole of its earliest formation, are sub-
jected to a kind of metamorphosis, the embryo first resembling
the structure of the lower classes of animals, before it reaches
the perfection of the human type. If during this change the
completion of any organ should be interrupted by any acci-
dental disturbance of the formative impulse, it remains in a
state which has a greater or less resemblance to that of an in-
ferior organization. Hence in many persons affected with the
blue complaint, the ventricles communicate with each other
by an opening in the septum, and both arteries arise from the
right, and none from the left.*

FISHES.

I 166. The heart in this class of animals is extremely small
in proportion to the body. Its structure is very simple, as it
consists of a single auricle and ventricle, which correspond
with the right side of the heart in warm-blooded animals.t The
ventricle gives rise to a single arterial trunk (which is expand-
ed in most fishes into a kind of bulb as it leaves the heart), going
straight forwards to the hranchtce, or organs of respiration.
The blood passes from these into a large artery, analogous to

cle, and the left ventricle beneath it) was driven to the right ventricle, to be pro-
pelled from it, and the intermediate one communicating with it to the whole body,
as well as to the lungs.

* At>ernethy's Surgical and Physiological Essays, part ii. p. 158.

Jo. Conr. Tobler De Morho Cceruleo. Gotting, 1812, 4.

J. C. Hein De istis Cordis Deformationibus qua sanguinem venosum cum arterioso
misceri permittunt. Gott. 1816, 4.

i See Tiidemian' 6 Armtomie des Fischherzens. Landshut, 1809.

M

162 ON THE HEART AND BLOOD-VESSELS.

the aorta, which goes along the spine and suppUes the body
of the animal ; it is then returned by the venae cavae into the
auricle;* a proof, among many others, of the power which
the arteries possess of returning the blood, independently of
the action of the heart.

§ 167. Most cold-blooded animals, as fishes, and the am-
phibia of this country, (Germany) have a much smaller pro-
portion of blood, and fewer blood-vessels than those with
warm blood. On the contrary, they have a much greater
number of colourless vessels arising from the arterial system.

INSECTS.

§ 168. A true heart, and system of vessels connected with
it, are found in a very few of what are called white-blooded ani-
mals. In this class they seem to belong only to some genera
of insects, which have no wings ; as the genus cancer, *f' and
monoculus. It has been proved by the excellent investigations
of Herold, J that the long dorsal vessel of the larvae, &c. com-
municating an undulating pulsation, and carrying a kind of
ichor, is protected on each side by a flat triangular muscle,
and that it is an organ analogous to the heart. In the genera
which we have mentioned, there seems to be no passage of
the arterial extremities into the origins of veins, and conse-
quently no true circulation.

It appears that insects possess neither blood-vessels nor absorbents.
Cuvier has examined, by means of the microscope, all those organs
in this class, which in red-blooded animals are most vascular, without
discovering the least appearance of a blood-vessel ; although ex-

* Representations of the heart of a fish are given by Perraul t, in the Essais de
Physique, torn. iv. tab. 19 ; by Duverney, in his posthumous CEuvres Anatomiques,
torn. ii. tab. 9; by Gouan, Historia Piscium, tab. 4, (all these however call the
trunk of the branchial artery, the aorta) ; and by Monro, in his Structure and Phy-
siology of Fishes ; and above all Tiedemann, in the work above cited.

t Willis De Anima Brutoi'um, tab. 3, fig. 1. Hösel's Insectenbelastigungen, vol.
iii. tab. 58 ; and Treviranus über den Innern Bau der Arachniden, s. 16.

t Über das Ruckeiigefass der Insecten, in the Abhandl. d. Naturforsch, Ges. iu
Marburg, b. i.

ON THE HEART AND BLOOD-VESSELS. 163

tremely minute ramifications of the tracheae are obvious in every part.
And Lyonet has traced and delineated in the caterpillar parts infi-
nitely smaller than the chief blood-vessels must be, if any such ex-
isted. Anatomie de la Chenille, &c.

Yet insects, both in their perfect and in their larva state, have a
memhrancus tube running along the back, in which alternate dilatations
and contractions may be discerned. From this circumstance it has
been supposed to be the heart ; but it is closed at both ends, and no
vessels can be perceived to originate from it.

It is obvious from these data, that the functions of nutrition and
secretion must be performed in the animals which we are now consi-
dering, in a very different manner from that which obtains in the
more perfect classes. Cuvier expresses the mode, in which he sup-
poses growth and nutrition to be effected, by the term " imbibition."
And he explains from this circumstance, the peculiar kind of respi-
ration which insects enjoy. Since the nutritive fluids have not been
exposed to the atmosphere, before they arrive at the parts for whose
nourishment they are destined ; this exposure is effected in the parts
themselves by means of the air-vessels, which ramify most minutely
over the whole body. " En un mot, le sang ne pouvant aller cher-
cher I'air, c'est Fair qui va chercher le sang." (Legons d'Anat. comp.
1. xxiii. sect. 2, art. 5.)

The heart of the crustacea, according to Cuvier, has no auricle,
and it is what he calls an aortic heart. For it expels the blood into
the arteries of the body, and this fluid passes through the gills previ-
ously to its reaching the heart again. The different parts of the sys-
tem are here found under a mode of connexion exactly the reverse
of what we observe in fishes, where the blood is sent into the gills,
and passes subsequently into the aorta. The circulating organ in
that class is therefore a pulmonary heart.

VERMES.

^ 169. In many genera of this class, particularly among the
mollusca* and testacea,f there is a very manifest heart,;|:

• See Swammerdam, of the Limax Maximus, tab, 9, of the Sepia Officinalis, tab.
52. Monro, On Fishes, tab. .'51. Cuvier, Tableau El^mentaire de I'Histoirc Natu-
relle des Animaux, tab. 8, fig. 1. Home, Phil. Trans. 1817 ; and of the Aplysi«
Fasciata. Cuvier, Mollusques, tab. ii, fig, 3.

f See Poll, Tesiacea tUriusqw SicilicB, vol. i. and ii. for a representation of this in
eeveral testacea. Willis, in the work above quoted, tab. 2, of the Oyster^ Swam-
Btterdam, tab. .5, of the Helix Pomatia. Stlebel, of the Helix Stagnulis.

t Cuvier divides the wiiole class of vermes, according as they are furnished with a
heart and vascular Bystem, or are destitute of these organs, into two families ; the
former l»e calls ■m«Uu$ca, the latter zoophyta,

M 2

164 ON THE HEART AND BLOOD-VESSELS.

which is sometimes of a singular structure. It consists, for in-
stance, in the cuttle-ßsh, of one ventricle, and two auricles,
which lie at some distance from the ventricle, near the gills.
Some bivalves are said by Poli to have two auricles, and some
even four. But in all these crustaceous animals, there has been
no connexion hitherto discovered between the arteries and
veins ;* while on the other hand some genera in other orders
of this class have a connected system of vessels without a
heart ;'f' and the proper zoophytes cannot be said to possess
either; as their nutrition seems to be effected by an imme-
diate derivation of the nutritive fluid from their abdominal ca-
vity into the gelatinous parenchyma of their body.

Baker, Fontana, Muller, and several other excellent natu-
ralists, have considered the dark portion in the body of the
wheel animal (vorticella rotatoria) to be a heart ; although it
has voluntary motion, which is influenced by that of the radii,
and they have employed this circumstance by a curious petitio
principii, to prove that there are animals which have a volun-
tary power of setting their heart in motion, or leaving it at rest.
I have shewn twenty-three years ago:]: that this remarkable or-
gan can by no means be looked upon as a heart, but is really
an alimentary canal.

According to Cuvier, the cuttle-fish has three hearts, neither of
which possesses an auricle. Two of these organs are placed at the
root of the two branchice ; they receive the blood from the body (the
vena cava dividing into two branches, one for each lateral heart) and
propel it into the branchiae. The returning veins open into the mid-
dle heart ; from which the aorta proceeds.

The other mollusca have a simple heart, consisting of one auricle
and ventricle. The vena cava assumes the office of an artery, and
carries the returning blood to the gills ; whence it passes to the auri-

* See Poli, torn. ii. tab. 25, of the Area Norn, and tab. 27, of the Ostrea Jacobtsa,
also torn. i. introduction, p. 39.

f B. F. Bening De Hirudinibus, Hal-derov. 1776, 4to. a very excellent mono-
graph; The medusa also have no heart, but a manifest circulating system of arte-
ries and veins. See Mitchell, in Albers's Americanischen Annalen, p. 121.

I The author completed his seventy-third year in the month of Sept. 1826 ; when
many of the most distinguished physiologists and men of letters in Germany came
to Göttingen for the purpose of celebrating a sort of philosophical jubilee in honour
of their distinguished countryman.

ON THE HEART AND BLOOD-VESSELS. 165

cle, and is subsequently expelled into the aorta. Here therefore, as in
the Crustacea, the heart is a 'pulmonary one.

The vermes of Cuvier have circulating vessels, in which contraction
and dilatation are perceptible ; without any heart. They can be seen
very plainly in the lumbricus marinus. The leech, naias, nereis, aphro-
dite, &c. are further examples of the same structure. This anatomist
is of opinion that the mollusca, Crustacea, and vermes, possess no ab-
sorbing vessels ; and he thinks that the veins absorb, as he finds
them to have communication with the general cavity of the body,
particularly in the cuttle-fish. Hence the above-mentioned classes
will hold an intermediate rank between the vertebral animals which
possess both blood-vessels and absorbents, and the insects which
have neither. (Legons, &c. 1. 23, sect. 2, art. 4.)
I The comparison of the circulating system in different classes of ani-
mals constitutes one of the most interesting and important branches
of investigation in the study of comparative anatomy ; and the stu-
dent should bear in mind that it was in the course of his inquiries into
the structure of the lower animals, that the immortal Harvey was led
to the discovery of the circulation of the blood. Much valuable in-
formation on this subject will be found in the lectures of Sir E.
Home, from which work we extract the following observations.

In animals that have no vascular system, consisting solely of a
membranous bag, there is much reason to believe no waste of mate-
rials takes place while in a quiescent state ; indeed the facts which
Mr. Bauer has published in the Philos. Trans., respecting the worms
that form the disease in wheat called by farmers the purples, of which
Sir E. Home has taken notice in the first volume of his Comparative
Anatomy upon the Digestive Organs of Worms and Insects, completely
establishes this fact. Mr. Bauer has preserved some of these worms
in a dried state, and has found, that although they have been kept so
for six years, and even longer, when moisture is applied to them,
and they are placed in the field of the microscope, they revive in five
or six hours, and move with great agility.

The animals next in order to these worms, are other genera of
vermes, in which there is a circulation, but no heart : of this kind
are all caterpillars and insects. In them the blood does not circu-
late, and probably remains at rest at those times in which the animal
is in a quiescent state ; but during the period of locomotion, or when
feeding, or using other muscular exertion, the blood undulates from
one end to the other of a large tube situated upon the back, at such
times supplying the different organs, and becomes aerated by the
air-vessels which pervade every part of the body.

Were animals classed according to the different modes of aerating
the blood, one great class might be formed of those animals, in which
the air circulates through the body, and the blood is confined to a re-
servoir ; another, when the blood circulates through the body, and the
air is only applied to a particular portion of it.

166 ON THE HEART AND BLOOD-VESSELS.

The heart will therefore be found to be of less importance than it
has been generally considered, and only to be an organ met with in
some of the higher orders of animals.

When we consider the aeration of the blood in insects, it must be
greater than in other animals ; and there is this curious circumstance,
arising out of the bodies being so abundantly supplied with air, as
soon as the cold is too great for their exerting muscular power, the
spiracula become closed, and the animal remains in a torpid state ; by
any increase of the warmth of the atmosphere, the air retained in the
tubes is rarefied, the external orifices of the spiracula are forced open,
and the functions of life are again carried on.

This fact is not to be doubted, since we see the same thing take
place in the vermes, when they shut up for the winter. The garden^
snail, as soon as the cold weather sets in, fixes itself upon any hard
substances, by throwing out a slime which cements the open edge of
the shell to the surface, and the snail remains there during the win-
ter-months ; ail the organs of the body being in a state of rest.

When warmth and moisture are applied, the membranous film
falls off; a globule of air that remained in the cavity of the lungs be-
comes rarefied, and forces its way out, and admits of fresh air being
applied to these organs.

In animals in which the circulation of the blood is carried on by
means of a heart, the blood is aerated in very different propor-
tions.

The aphrodite aculeata has, properly speaking, no blood-vessels ;
the water is received by thirty-two lateral openings between the feet,
into the cavity under the muscles of the back, and there applied to
the surfaces of the projecting cells, of which th^re are two rows, fif-
teen in each ; through these the air in the water is communicated to
the coeca contained in them, which Sir E. Home considered to be the
respiratory organs.

In the leech there is no heart, but a large vessel upon each side of
the animal ; and the water is received through openings into the
belly, into the cells or respiratory organs, and passes out through the
same.

In the earth-worm there is an artery that passes up the back, and a
corresponding vein passing down from the head upon the middle of
the belly ; near the head, there are five pair of lateral canals that
swell out beyond the size of the large vein, so that they become re-
servoirs of blood to supply the vessels of the head, when wanted to
bore through the earth, and the action of the muscles so employed
will, by their situation, accelerate the circulation. The oesophagus,
lying in the center of these reservoirs, will, by the action of its coats
while the animal is eating, have an influence on the circulation.
The blood is aerated by lateral cells in the same manner as in the
leech.

In the muscle, the gut passes through the heart, which is an oval
bag, having no auricle, unless the two large veins are called such j the

ON THE HEART AND BLOOD-VESSELS. 167

coats of the ventricle are very thin, but the action of the intestine
makes up for this deficiency.

In the earth-ivorm, the circulation is properly in a circle without
beginning or ending. One vessel runs upwards to the head, along
the back, communicating with the lateral reservoirs, but still a conti-
nued tube goes on. It is the same with the vein or opposite vessel
that runs down the tail, and the branches that go from the artery to
the lateral cells, have corresponding branches returning the blood to
the great vein. This may be considered as one mode of circulation
peculiar to this tribe ; and it is admirably contrived that the blood
may be accelerated in its motion by the muscular action of the body
of the animal, without any increase of action in the arterial sys-
tem.

The aeration of the blood in this mode of circulation is imperfect,
only one portion being aerated and mixed with the rest, in which no
such changes have been produced.

In the lumbricus marinus, although the principle of the circulation is
the same, there are many strongly marked differences in the mode
of carrying it into effect.

There is, as in the ierrestris, one trunk behind, going from the tail to
the head, and one from the head to the tail on the belly, completing the
circle ; but in this animal there are external gills, which remain pro-
truded while the animal is in the water, and the blood has such a ve-
locity in these vessels, that they may be considered as so many small
ventricles ; this is an approach to the construction of the gills of the
sepia. In this circulation there are two regularly formed auricles,
supplied by lateral veins from the viscera attached to the sides of the
great artery, so as to increase the supply of the blood, and afford
quantity as well as velocity ; while it gives off branches to the gills,
the main trunk pursues its course, supplying the body. In this ani-
mal, it is only a portion of the blood which is aerated, and from the
structure of the gills that must be in a much greater degree than in
the lumbricus ierrestris.

The animal whose heart is nearest in structure to those described
is the oyster, in which the whole blood is aerated in passing through
the gills, before it is received into the auricle. In this animal, the
auricle and ventricle are very thin in their coats, so much so as to
make them unequal to apply force to the blood ; but the ventricle is
laterally connected to the great muscle, whose action will accelerate
the circulation.

In the toredo navalis the heart is situated upon the back of the ani-
mal near the head, consisting of two auricles of a thin, dark coloured
membrane ; the auricles open by contracted valvular orifices into
two white stony tubes ; those united form the ventricle which termi-
nates in an artery that goes to the bony shell. I'he heart is loosely
attached ; its action is distinctly seen through tlie external covering
and in some instances continues to act after it is laid bare.

'I'hc first contraction is in the two auricles, whicli are shortened in

168 ON THE PIEART AND BLOOD-VESSELS.

that action, this enlarges the ventricle before it contracts. The great
artery from the ventricle goes directly to the head, and the vessels
that supply the auricles are seen to come from the gills. The auri-
cles are lined with a black pigment, so that their contents cannot be
seen through their coats ; and the ventricle from its thickness is not
transparent, but the muscles of the boring shells are of a bright red,
and all the parts between the heart and head are supplied with red
blood.

The structure of the heart is different from that of the lumbricus
marinus, and consequently the circulation is by no means peculiar.

This animal's heart may be said to be the first in this series that is
complete, and this first regular circvdation of the blood, every part of
which passes through the vessels of the gills, and even through the ca-
vities of the heart. As this animal is to work a machine capable of boring
a very hard substance, and to go on working during the whole of that
period of life in which its growth is continued, to make room for the
increased bulk, so it requires that the blood be more highly aerated
and supplied with greater velocity to these active organs. The heart
also, to give it greater advantage in these respects, is placed near to
the boring shells, so that the blood which goes to them, is of the
brightest colours.

In this circulation the first action of the heart is to supply the dif-
ferent parts of the body with aerated blood ; upon this the activity of
the heart is wholly exerted ; the blood is returned more slowly
through the gills, and remains there a longer time, so as to receive a
greater degree of the influence from the air contained in the water. .

This is the principle on which the circulation of many of the
vermes is established, and is exactly the reverse of what takes place in
fishes, reptiles, and the higher orders of animals.

The mode in which the breathing organs of the torediues are sup-
plied with water, makes it evident that all sea-worms which have no
cavity for the reception of sea-water, must have the breathing organs
placed externally, as is the case with all those species of actinia met
with in the West Indies, called aniinal flowers, and the beautiful mem-
branous expansions they display, resembling the petals of flowers,
are in fact the breathing organs acting at the same time as tenta-
cula.

In the sepia this mode of circulation is rendered more complex,
but the same principle is adhered to. In the torediues the water is in-
timately applied to the gills from the simplicity of their structure ; but
in the sepia they are more complex, and require force to apply the
water to every part of them, and for this purpose there is a bulb and
double valve placed at the roof of each gill.

In the sepia the blood is brought to the gills from all parts of the
body by three sets of veins, all branching off from the trunk of the
vena cava. The common trunk that goes to each gill, is of so large
a size and so thin in its coats, that to prevent the regurgitation of the
blood, the valve is interposed ; the blood having got into the gills,

ON THE HEART AND BLOOD-VESSELS. 169

and having pervaded every part of the branchiae, it is conveyed by a
smaller trunk to the auricle, so that the gills vpill never be completely
emptied ; it is then received into the ventricle, and carried into every
part of the body. The circulation is also similar in the lamprey, lam-
pores, the myxene, and an animal nearly allied to it from the South
Seas, which has never received a specific name, although there are
peculiarities in the gills from which these animals must be considered
in their aeration inferior to fishes at large.

In the lamprey and lampern, the water is received by the seven la-
teral openings on each side of the animal into the bags that perform
the office of gills, and passes out by the same orifices, the form of the
cavities being such as to allow the water to go in at one side and out
at the other, after having passed over all the projecting parts. Some
of the water escapes into the middle tube, and from thence passes
out either into the other bags or at the upper end into the oesopha-
gus.

The muscular structure of the branchial artery of the dog-fish, and
the direction in which that artery leaves the ventricle, are exactly the
same as in the squalus maxhnus, only they are seen on so small a
scale, that they do not arrest our attention ; but when magnified to
the same size which they acquire in this fish, they make a stronger
impression upon the mind, and force us irresistibly to inquire after
their use. The direction of the artery appears to be common to fishes
in general, but the muscular structure that is met with in the bran-
chial artery, is confined to particular tribes. Sir. E. Home met with
it in the srurgeon, and says it is common to sharks.

In tlie ivolf-ßsh, the anarhichus lupus, the muscular structure of the
branchial artery is nearly the same, but the valves are placed close to
the opening of the ventricle, and only two in number. In the turbot
there is no muscular structure in this part, but the coats are extremely
elastic, and admit of being very considerably dilated, particularly at
its origin, where three valves are placed, and so contrived, that the
dilatation of the artery makes them shut more closely.

In the lophius piscatorius there is no appearance of muscularity in
the coats of the branchial artery, and no lateral valves, as in other
fishes ; but there is a muscular tube half an inch long, rising from
the edge of the opening of the ventricle, which projects into the ar-
tery.

These different structures, so unlike one another, and bearing no
resemblance to the mechanism in the same parts in quadrupeds,
make it probable that the circulation through the gills is impeded by
the external pressure of the water in different degrees according to
the depth of the fish from the surface ; therefore in tliose fishes
which frequent the great depths, as the squalus, in all its tribes, there
is a muscular structure in the coats of the branchial artery, which,
when the fish is deep in the water, by its contraction diminishes the
area of the vessel, and makes the valves perform their office ; but
wlicn the fish is near the surface, this muscular structure, by its re-

170 ON THE HEART AND BLOOD-VESSELS.

laxation, renders the area of the artery so wide, that regurgitation of
the blood takes place into the ventricles, and prevents the small ves-
sels of the gills from being too much loaded.

That such regurgitation can take place when the muscle is relaxed,
is ascertained by the ventricle being readily injected after death with
coarse injection from the artery, the valves allowing it to pass.

In fishes that swim deep and do not come to the surface, as the
wolf-fish, the regurgitation does not take place into the ventricle;
but the relaxation of this muscular portion of the artery allows it to
dilate and form a reservoir, and the valves remain closed so as to
prevent more blood leaving the ventricle.

In fishes residing at moderate depths, as the turbot, elasticity is
employed as a substitute for muscular powers, there being less varia-
tion. In the lophius piscatorius, which probably never descends
into water of great depth, the ventricle is so weak that the supply of
blood to the gills is regulated by the contraction and relaxation of a
muscular valve.

The heart of the inanatee, or dugong of the West Indies, has its
ventricles completely detached from each other : when we compare
this with the heart of the vjhale tribe, we find that the right ventricle
in the whale is a nearer approach to the left than in the quadruped.

The ventricles in the dugong, although similar in structure, are not
exactly of the same size. The left is thickest, and half an inch
longer.

The auricles resemble those of the whale, having the same trans-
verse ligamentous bands.

The valves had nothing particular in their appearance.

The foramen ovale was entirely closed, but its situation was dis-
tinctly seen.

The relative size of the aorta and pulmonary artery was the same
as in the elephant.

171

CHAPTER XIII.

OF THE ABSORBING VESSELS.

§ 170. It was regarded as an axiom even by Valsalva, that
those animals, which have true blood-vessels, have also an
absorbing or lymphatic system. It appears also that the con-
verse of this proposition is true : viz. that those classes only
have true lymphatic vessels, which possess at the same time
a perfect circulating system of blood-vessels ; that is, only the
four classes of red-blooded animals.

In many of what are called white-blooded animals, there is
a kind of absorption very evident ; as in the armed polypes,
whose parenchyma becomes tinged in a short time with the
colour of those insects which have been swallowed. The ex-
istence of absorption is inferred by analogy from other pheno-
mena, as the metamorphosis of larvce, Sec. But no true
system of real absorbing vessels has been hitherto demon-
strated in these animals.*

§ 171. This system (which comes most properly under con-
sideration in the present chapter, on account of its relation to
the circulation of the blood) consists of the lacteal vessels,
which arise from the small intestines, and of the proper It/m-
phatic vessels, which belong to the rest of the body. It in-
cludes also the conglobate glands, which are found in most of
the animals which have this system, and seem to consist
merely of a congeries of vessels ; and lastly, the thoracic duct,

* Sheldon has ascribed absorbing vessels to the silk-worm, and other larva. See
his history of the absorbent system, part i. p. 28 ; and Monro to the echinus eiculen-
tiu, (sea hedgehog) in his Phytiol. of Fishes, p. 88.

172 OF THE ABSORBING VESSELS.

which is the chief canal for conveying the fluids from the
lymphatic system into the blood.

The structure and offices of the absorbent glands have been illus-
trated by the observations of Mr. Abernethy on the formation of
these parts in the whale. He found the mesenteric glands of that
animal to consist of large spherical bags, into which several of the
lacteals opened. Numerous vessels ramified on these cysts ; and the
injection passed from their secerning extremities into the cavity. In
the groin and axilla of the horse he also found them to consist of one
or more cells. Hence there can be no doubt that the absorbed fluid
must receive an addition in its passage through these bodies. Philos.
Trans. 1796, pt. 1.

It has been much questioned whether the lymphatics have any
communication with the venous system prior to the termination of
the thoracic duct. The observations of that ingenious veterinary
surgeon, Mr. Bracy Clark, have determined this question in the
affirmative ; as he has found the trunk of the lymphatic system to
have several openings into the lumbar veins in the horse. Rees's
Cyclopcedia, article Anatomy Veterinary.

The communication of the lymphatics with the veins in the four
classes of vertebrated animals has of late years been demonstrated by
Lippi, Fohmann, and Lauth, and in the anatomical museum of Heidel-
berg there are numerous beautiful specimens shewing this fact.

MAMMALIA.

§ 172. All the parts of the absorbing system, which have
been just enumerated, are most perfect and manifest in this
class of animals : it is well known indeed that all the chief
parts of this important system of vessels have been first disco-
vered in mammalia. When their lacteals contain chyle, they
are distinguished by their white colour from the other absorb-
ing vessels, the contents of which are either limpid, or of a
slight yellow tinge. The former vessels run together in con-
siderable trunks, particularly in the sheep and goat : the lat-
ter, or true lymphatics, may be seen to advantage on the hind-
leg of the horse, where they follow a tortuous course.

The thoracic duct is double in some quadrupeds,* as in the
dog, and forms at its commencement, more constantly than in
the human subject, a vesicular enlargement, called the cisterna,

* Pecquet, Exjyerimenta Nova Anatomica, p. 21, ed. of 1654.

OF THE ABSORBING VESSELS. 173

or receptaculum chyli. The course and distribution of the
thoracic duct vary in quadrupeds, at least in our domestic
animals, as much as in the human subject. It forms, not un-
frequently, in the dog a kind of annular portion at its upper,
or more properly anterior end ; which trivial variety Van Bils
transformed into a constant and important circumstance, and
called " receptaculum tortuosum" *

In many mammalia, particularly of the order ferce, the me-
senteric glands are collected into one mass, which is known by
the inappropriate name of 'pancreas Asellu.-\

Sir Everard Home has found that in the sea-otter the receptaculum
chyli sends two trunks to form the thoracic duct. These have fre-
quent communications ; so that there are sometimes three, frequently
four, and never fewer than two trunks running parallel to each other.
PUlos. Trans. 1796, pt. 2.

BIRDS.

§ 173. The chyle is transparent in this class ; therefore the
lacteals are only distinguished from the lymphatics by their
situation and office. There are no glands in the mesentery,
although conglobate glands are found in other parts in several
of the larger birds. Their thoracic duct is double.:j:

In a communication made to the Academy of Medicine at Paris in
1819, M. Magendie denied the existence of lymphatics, with few ex-
ceptions, in the class of birds. He dissected more than fifty birds of
different kinds, and was not enabled to discover the lymphatics in any
part of the body except in the neck of the swan and goose ; in this
part he found the lymphatics and glands as in mammalia, filled with a
diaphanous and colourless lymph. The opinion of Magendie has been
satisfactorily refuted by several anatomists, particularly by Dr. Lauth
of Strasburg, who, in an excellent treatise, entitled Memoire sur les
vaisseaux Lymphntiques des Oiseaux et sur la maniere de les preparer,
has proved the existence of lymphatics in birds. §

* He has represented it in a very beautiful plate, as far as the engraving goes, in
his Responsio ad Admonitiones, Jo. Ab. Home. Roterod. 1661, 4, p. 7.

t Asellius De Ladibus, tab. 1 and 2.

X Hewson, in the Phil. Trans, vol. Ivii. tab. 10, of the cock. See also Magendie,
in his Journal de Physiologie ExipirimeiUale, torn. i. 1821.

$ See the wrork recently published by Fohmann, Teacher of Anatomy at Liege, en-

174 OP THE ABSORBING VESSELS.

AMPHIBIA.

§ 174. Lacteals are found in great number in the delicate
mesentery of the turtle. The thoracic duct is double. There
seem to be no lymphatic glands at all.*

The distribution of the lymphatics on the intestine of the turtle
forms one of the most elegant preparations in comparative anatomy.
By fixing the injecting tube in a vessel near the intestine, and wait-
ing with a little patience, the quicksilver will gradually find its way
into the minute ramifications of the lacteals. The peritoneal surface
of the gut is covered with very minute straight parallel branches,
running according to the length of the intestine. Its inner surface is
no less thickly covered with lacteals of a different appearance. When
dried it seems as if the quicksilver were contained in small cells, co-
vering the whole internal surface of the intestine so completely that
the point of a pin could scarcely be placed between them.

FISHES.

I 175. The lymphatics of these animals seem to be desti-
tute of glands and valves: they want also the lymphatic glands,
and their thoracic duct divides, at least towards its anterior
part, into two chief branches. +

titled Das Saugader System der Wirbelthiere Von. Vin, Fohmann, Das Saugader
System der Fische. Heidelb. and Leips. 1827, representing the lymphatics of the
stomach, liver, spleen, intestines, genital organs, and fins, as well as the thoracic
duct of the gymnotus electricus, eel, pike, &c. Professor Fohmann has announced his
intention of delineating and describing the lymphatics in the other classes of verte-
brated animals in a future publication.

* Monro's Physiol, of Fishes, tab. 30.

t Hewson and Monro, in the works quoted above. See also Bartholin, Jhiat,
Benov. p. 609, of the cyclopterus lumpiis (lumpsucker).

175

CHAPTER XIV.

ON THE ORGANS OF RESPIRATION.

§ 176.* The incessant continuation of the great chemical pro-
cess by which oxygen, the true pabulum vitae, is exchanged
for hydrogen and carbon, is essentially necessary to the well-
being of the greater part of animals. Yet the organs and
mechanism by which this wonderful function is carried on
vary very considerably ."f In the mammalia after birth ; in
birds, when they have left the egg; and in amphibia when
completely formed, the chief organ of this function is the
lungs ; in fish it is performed in the gills ; in most insects in
their trachece ; in the vermes, in analogous, but at the same
time very different parts.

MAMMALIA.

^ 177. The lungs of quadrupeds agree on the whole in
structure, form, and connexion, with those of the human sub-
ject. In the cetacea, on the contrary, and in the web-footed

* Much instructive information on the respiratory system in different animals may
be found in Geoff. St. Hilaire, Philosophie Anatomique. Par. 1818.

t Aug. Broussonet VaricB Positiones circa Respirationem. Monspel. 1778, 4; also
Ludwig's Delectus Opusculor. ad Scient, Naturalem spectant. Lipsiae, 1790, 8,
p. 118.

Chr. L. Nitzsch De Respiratione Animalium, Viteb. 1808, 4.

G. J. Van Der Boon Mesch De Circulatione et Respiratione Animalium Pulmonibus
instructorum, Leid. 1812, 4.

Fouquet De Organi Respiratorii in Animalium serie cvolutiom, Jen. 1818, 8.

A. F. Schweigger's Classification der Thiere nach den Respirations-Organen, im
Königiberger Archiv, fwr Naturmss. etc. i. th. p. 90.

17G OF THE ORGANS OF RESPIFvATION.

mammalia, (as the manati) which approach most nearly to
them, they are distinguished by a firmer texture, particularly
of the investing membrane, and by their peculiar form ; since
they are not divided into lobes, but have an elongated and
flattened appearance. They are adherent to the pleura, as
well as to the very strong and muscular diaphragm.*

BIRDS.

§ 178. The respiratory organs of this class constitute one
of the most singular structures in the animal economy, on ac-
count of several peculiarities which they possess ; but more
particularly in consequence of their connexion with the nu-
merous air-cells which are expanded over the whole body. +

The lungs themselves are comparatively small, flattened, and
adherent above to the chest, where they seem to be placed in the
intervals of the ribs ; they are only covered by the pleura on
their under surface, so that they are in fact on the outside of the
cavity of the chest, if we consider that cavity as being defined
by the pleura; a great part of the thorax, as well as the ab-
domen, is occupied by the membranous air-cells,J into which
the lungs open by considerable apertures. Those of the tho-
rax are divided, at least in the larger birds, by membranous
transverse septa into smaller portions,§ each of which, as well
as the abdominal cells, has a particular opening of communica-
tion with the air-cells of the lungs, and consequently with the
trachea. The membranes of these cells in the larger birds are
provided here and there with considerable fasciculi of muscu-
lar fibres, which have been regarded as a substitute for the
diaphragm, which is wanting in this class of animals. || They

* Tyson's Anatomy of a Phocana, p. 30.

t Ladisl. Cliernak De Respiratione Volucrum, 1773, 4to. Fuld De Organis qiiibus
Aves spiritum ducunt. Wirceb. 1816. Harvey De Generat. Animal. 1651.

i Discovered by Harvey, De Generatione Animalium, p. 4.

§ Perrault, Essais de Physique, torn, iii, tab. 18, of the ostrich.

II Casp. Bartholin Diaphragmatis Structura Nova. Paris, 1676, 8, p. 31. Modern
zootomists have been divided on the question, which of the membranes, in or about

ON THE ORGANS OF RESPIRATION. 177

also serve very principally, as we may ascertain by examining
large birds in a living state,* to drive back again into the
lungs the air which they received in inspiration, whence the
repletion and depletion of the thoracic cells must alternate
with those of the abdominal cavities. t

The cartilaginous annuli of the trachea, which are in general more
complete in the other mammalia than in man, are perfect circles in
birds, and overlap each other at their upper and lower margins.
Hence the diameter of this part is not affected by any twisting motion
of the neck.

The air-vessels are considerably larger than in the mammalia, and
the substance of the lungs is not divided into lobuli. The cartilages
of the trachea are lost before that tube enters the lung, and some
of its large branches open on the surface of the viscus. In the
ostrich this aperture is surrounded by circular muscular fibres, a
peculiarity which does not seem to have been hitherto noticed

§179. Besides these cells, a considerable portion of the
skeleton is formed into receptacles for air in most birds ; for
there are indeed exceptions and considerable variations in the
different genera and species. This structure is particularly
marked in the larger cylindrical bones, as the scapula, clavicle,
and femur. It is also found in most of the broad and multan-
gular bones of the trunk, as the sternum, ossa innominata,
dorsal vertebras, &c. All these are destitute of marrow:|: in
the adult bird, at least in their middle ; so that the cylindrical
bones form large tubes, which are only interrupted towards
the extremities by a sort of transverse bony fibres ; the broad
bones are filled with a reticulated bony texture, the cells of
which are empty. They have considerable apertures § (most
easily shown in those extremities of the cylindrical bones

the chest of the bird, can be properly compared to the diaphragm. See J. Hunter,
in the Philos. Trans, vol. Ixiv. part i. p. 207 ; and Mich. Girardi, in the Memorie
della Societu Italiana, torn, ii, part ii. p. 739.

* Wepfer, CicutcB Aquaticce Ilhtoria, p. 171.

t J. B. Du Hamel, Histenia Academ. Reg. Scient. p. 141.

} This fact was known to the Emperor Frederic II. See his treatise De Art»
tenandi cum Avibus, p. 39 of Schneider's edition.

J Camper's Kleine Schriften, vol. i. part i. tab. 1 and 4.

N

178 ON THE ORGANS OF RESPIRATION.

which are turned towards the sternum) communicating with
the kings by small air-cells ; which facts may be shewn by va-
rious experiments on living and dead birds.*

These receptacles of air probably serve the purpose of
lightening the body of the bird in order to facilitate its mo-
tions. This effect is produced in most birds to assist their
flight \f in some aquatic species, for the purpose of swimming ;
in the ostrich and some others for running. Hence we find
-the largest and most numerous bony cells in birds which have
the highest and most rapid flight, as the eagle, &c. And
hence also the bones of the bird which has just left the egg,
are filled with a bloody marrow, which is absorbed soon after
birth, entirely in some, in others, particularly among the
aquatic species, for the greater part.

We may however conclude on the other hand, that all
these bony receptacles of air are not, like those of the thorax
and abdomen, immediately connected with the respiration of
the animals. For in many birds the interval between the two
tables of the cranium contains air, while the apertures for its
admission are not connected with the lungs, but merely with
the Eustachian tube.

§ 180. The immense bill of some birds, which are for that
reason called levirostres, is provided with air from the same
quarter. This structure is not therefore connected, as some
anatomists J have supposed, with the organ of smelling, but
forms a part of the air-cells.

^181. Besides the uses which have been already pointed
out, these receptacles of air diminish the necessity of breath-
ing frequently in the rapid and long continued motions of se-

* Some curious experiments have been made on this subject by Dr. Albers. He
made living birds respire the different gases through the air-cells of their bones by
means of an apparatus invented for the purpose. See his Beyträge »ur Anatomie
und Physiologie der Thiere, parti. Bremen, 1802, 4, p. 110.

t Willis De Anima Brutorum, p. 30. Reimarus, in Reil's and Autenrieth's
Archiv, vol. xi. p. 229.

■If Cajet. Monti, in the Comment. Instit. Bowon. torn, iii. p. 298; and recently Si
Traill, in the Trans, of the Linnßan Society, vol. xi. p. 11.

ON THE ORGANS OF RESPIRATION. 179

veral birds, and in the great vocal exertions of the singing
birds.^ They are also obviously serviceable in the evacuation
of the fasces, and probably assist in the expulsion of the egg.

The bones of birds, in so far as their air-cells are concerned, form
two distinct systems, the one being filled with air through the trachea
and lungs, the other immediately from the mouth or nose. To the
latter the bones of the head, to the former those of the trunk, of the
neck and extremities belong. With very little practice one may tell,
in a bone fully developed, whether it contains air-cells or not, from
the mere external appearance, without at all seeing the opening
through which the air enters. Such bones, in addition to their being
devoid of marrow, are generally of a clearer white colour than those
filled with marrow. Frequently the external walls of the air-bones
are so thin that their internal cells can be very well seen. Neverthe*
less, mere external appearances may deceive, and in order to pre-
vent this the openings leading to the air-cells should be sought for-
These openings are in general, as their connexion with the lungs or
air-tubes renders necessary, situated in concealed parts, and the ex-
tremities of bones. This circumstance, coupled with their smallness,
makes their discovery so difficult, that in many cases not only the
cleaning of the skeleton and the separation of the bones from all their
connexions, but also the minutest examination of their surface, are
necessary to discover their existence. In long bones the openings tq
the air-cells is generally situated close to either extremity. In bones
which exist in pairs there is commonly only one, or where several
exist they are so close together as to be nearly united. The direction
in which the openings penetrate the bony parietes is not uniform.
Sometimes it is oblique, so that a short oblique canal is formed ; at
others there is an oblique groove with a sieve-like base for the entrance
of the air. The edges of the openings are even, smooth, and rounded,
which gives them a peculiarly regular appearance. Their shape is
either circular, oval, or elliptical. Their breadth bears some kind
of proportion to the size of the bone, or at least to the extent of
the internal cells, so that large birds, and large bones, have much
larger openings than the small ones. There are, however, very re-
markable exceptions. With respect to the internal air-cells great
differences exist. There has been found in the internal periosteum
which lines the air-cells, in the bones of the upper and lower extre-
mities, a fine net-work of blood-vessels. It is known that the air-
bones in young birds are filled with marrow, which becomes gradu-
ally absorbed to make room for the admission of air. This gradual
expansion of the air-cells, and absorption of the marrow, can no
where be observed so well as in young tame geese when killed at dif-

• Willis De Anima Brutorum, p. 30.
N 2

180 ON THE ORGANS OF RESPIRATIOF.

ferent periods of the autumn and winter. The limits to the air-cells
may be clearly seen from without by the transparency of the bony
parietes. From week to week the air-cells increase in size, till to-
wards the close of the season the air-bones become transparent. In
all these bones the marrow first disappears from the vicinity of the
opening which admits the air, and continues longest at the points
further removed from this opening. Towards the close of the sum-
mer and beginning of autumn, although in external appearance the
young goose resembles the parent, no trace of air-cells can be disco-
vered in Its bones, the interior of the bones being then filled with
marrow. About the fifth or sixth month the marrow begins to dis-
appear. This circumstance, which applies also to other birds, shows
with what caution one should form an opinion, from young birds only,
on the size of the air-cells. In many kinds of birds the air-cells of
some bones are never fully developed, although they have the open-
ings in the bones which lead to the air-cells. The obvious use of this
construction in the bones of birds,^ appears to be that of lessening the
weight of the bone as compared with its size, without at the same
time diminishing their necessary peripherical extent. Whether birds
possess the power of voluntarily letting out the air so as to render
them specifically lighter, or whether they contain lighter gases in
them, has not been ascertained. Fid. Nitzsch-s Osteograf. Beitrage,

" In the eagle, Tiawk, stork, lark, and other high flying birds, these
cells are very large ; and in many of those birds there are stilljarger
cells, ascending under the integuments of the neck, and passing be-
neath the skin of the inside of the arm and back of the shoulder; In
the stork we find these cells large enough to admit the finger to pass
a considerable way down upon the inside and back of the wing. They
are also large in the owl and other birds of prey." Macartney in
Rees's Cyclopedia^ art. Birds.

AMPHIBIA.

§ 182. The lungs of amphibia* are distinguished from
those of warm-blooded animals, both by a great superiority in
point of size, as well as by a greater looseness of texture ; which
circumstances are serviceable in swimming in many of these
animals.

It is well known that the lungs of turtles and frogs do not
collapse on opening the animals, like those of mammalia, but
often remain expanded, at least partially, for some time. Mal-

* On the respiratory system of this class, see Meckel, in his Archiv, vol. iv. p.
60.

ON THE ORGANS OF RESPIRATION. 181

pighi, and lately Townson,* have explained this phenomenon
by the action of the constrictor muscles of the glottis. Bre-
mond thought this insufficient according to his experiments,
and ascribed much effect to the peculiar vitality of the lungs.f

The amphibia are distinguished in all instances by the great size of
their air-vesicles. In the/ro^s, lizards, and serpents, the lung consists
of a cavity, the sides of which are cellular. The lower, or posterior
part of the organ, either forms a mere membranous bag (the parietes
of which are not cellular), or else the vesicles are larger at that part
than elsewhere. In the serpents the lung has that elongated form,
which characterizes all the viscera of these animals. A considerable
portion of it is a simple membranous cavity ; and this is supplied
•with arteries from the surrounding trunks. The turtles have a more
complicated structure, or one which approaches more nearly to that
of the warm-blooded classes. The lungs are uniform in their texture
throiighout, but the vesicles are very large. The cartilaginous an-
nuli of the bronchi terminate before these vessels enter the lungs.

§ 183. There are numerous projecting processes in the
lungs of the cliameleon% and newt; in the latter animal they
terminate behind in an elongated bladder. The serpents, at
least for the most part, have only a single lung, which forms
an elongated vesicular bag. In a coluber of four feet and a
half long, the lung measured one foot one inch ; its anterior
half resembled a muscular intestine in appearance, and had an
elegantly reticulated internal surface, which resembled on a
small scale the inner surface of the second stomach of the
ruminating animals. The posterior part formed merely a
simple and long cavity with thin sides.

§ 184. In the tadpole, and the young of such lizards as
bring forth in water, there are two organs, which somewhat
resemble the gills of a fish {appendices ßmbriatce, Swammer-
dam).§ It has been doubted whether the young of the true

* De Amphihiis. Goett. 1794, 4.

f See on the same subject Rudolphi's experiments, in his Anatomisch-Physiologis-
che Abhandlungen, p. 119. G. R. Treviranus, Biologie, vol. iv. p. 141 ; and espc'
tially Const, de Weltzien De pulmonum autenergia in organico respiralionis mechu'
nimo. Dorp. 1819, 102.

i Vallisnieri's htoria del Cameleonte, p. 68, tab. 3.

§ Biblia Natura, p. 822. Rösel, tab. 2, fig, 18 ; and especially Conr. de

18^ ON THE ORGANS OF RESPIRATION.

salamander are provided with these appendices ; and Latreille,
in his Histoire Naturelle des Salamandres de France, p. 19,
and seq. has the following question, " Lesjeunes salamandres
terreslres out elles des branches? voila une question que je
mets encore au rang des problemes." I answered this question
in the affirmative forty-one years ago ; having observed that
the young of some pregnant salamanders, whom I kept in my
room in glasses, and who brought forth under my inspection,
had considerable branchial appendices.* These appendices
are connected to the sides of the neck, and hang loose from
the animal ; they are not permanent, but are gradually with-
drawn into the chest, (within a few days, in the reptiles of
this country (Germany), where their remains may still be per^
ceived for some time + near to the true lungs. That doubtful
animal, the siren lacertina from Carolina, has, according to
Hunter's dissection, two bladder-like lungs, besides the exter-
nal branchise.^

The same circumstance holds good respecting that no less
mysterious creature, \)s\q proteus anguinus, from the Cirknitz
or Sitticher lake of Carniola ; whose remarkable internal struc-
ture has been described and delineated by Dr. Schreibers in
the Philos. Trans, for 1801 ;§ and more recently by Signors
Configliachi and Rusconi in their elaborate monograph on the
proteus anguinus.

- Instead of the branchial opening by which fishes again dis-
charge the water, which they have taken in at the mouth,

Hasselt Observationes de Metamorphosi quurundam partium RancB temporarieE. Groning'.
1820 ; and ÄI. Rusconi Degli organi della circolazione delle lane delle Salamandre
aquatiche. Paris, 1817.

* See the Specimen Physiologicc comparatce, in the 8th vol. of the G'ottiitgen Com-
mentaries.

t Swammerdam, loo. citat. Kosel, p. 82, tab. 19, fig. 2.

I Philos. Trans, vol. Ixv. p. 307.

§ On these two mysterious animals, as well as the larvae of several frogs and sa-
lamanders, consult Cuvier's Recherches Anatomiipies sur les Reptiles regardis encore
comme douteux par les Naturalises. Par. 1807; Humboldt's Travels, and Bon-
pland's 2nd part of his Observations d' Anatomie cornparee, ler vol. 181 L Configli-
achi et Rusconi Monografia del Proteo ängüino. Pa.v. 1819.

ON THE ORGANS OF RESPIRATION. 183

some tadpoles have for this purpose a canal on the left side of

the head near the eye,* which must be distinguished from the

small tube on the lower lip, by which they attach themselves

to aquatic plants.*!-

After an elaborate anatomical description of the proteus anguinus,
Signors Configliachi and Rusconi proceed to inquire whether it be
true, as many naturalists have believed, that this reptile breathes
with its branchiae and lungs at the same time, and, secondly, whether
the sirena lacertina is to be considered by zoologists as a larva, or as
a perfect animal. In respect to the bony apparatus of the branchifs,
they found a remarkable difference between the proteus, the sirena,
and the larvae of salamanders and frogs, botli as to form and hardness.
In the sire}i and lai'vcE there are four branchial arches on each side,
which are furnished with several projections on the surface ; in the
proteus there are but three arches, which are perfectly smooth ; those
of the proteus are osseous, while those of the siren and larz<£ are cartila-
ginous. These differences did not escape M. Cuvier, who in speaking
of the proteus, observes, that the bony apparatus of the branchias is
much harder than it is in the sirena and the axolotl. Signors Con-
figliachi and Rusconi observed in the larvce of frogs, that when tlieir
spine is nearly hardened into bone, and their metamorphosis is
beginning to be accomplished, the branchial arches become softened,
and ready to be absorbed. They observed the same thing in the
larvae of salamanders, with this difference, that the ossification of
the spine takes place in the latter much sooner than the period
of their metamorphosis ; and when that period arrives, the portion of
their branchial apparatus, which remains to be converted into the os
hyoides, instead of softening, becomes hardened into bone. Thus
their observations fully confirm the conjecture of M. Cuvier, who, in
his description of the axolotl, has observed, that the apparatus sup-
porting the branchiae has a great resemblance to that of the sirena,
and that probably, at the period of its metamorphosis, a portion
remains to form the os hyoides of the salamander. Now, if the
branchial arches of the sirena, dissected by M. Cuvier, were entirely
cartilaginous, although the cranium, the lower jaw, and the vertebrce,
were already perfectly ossified, and if these are similar, in form and
number to those of the axolotl, which, in the opinion of M. Cuvier
himself, is a larva, and if, moreover, the branchial arches of the
proteus, which is a perfect animal, are osseous, and different in
all respects from those of the larvae hitherto known, do not all these
facts furnish us with a strong argument to prove that the sirena

* llösel, tab. 8, fig. 7, 8. Tliis organ is very conspicuous in the lurge larva; of
the rana paradoia,

t Rösel, tab. 14, fig. 17. Rosenthal, in tiie Verliandl. der Berlin naturfur&ch,
CeuUicli, vol. i. part 1, 1819.

184 ON THE ORGANS OF RESPIRATION.

lacertina is a perfect animal, and therefore essentially different from
the proteus ? Signors Configliachi and Rusconi, after a minute exa-
mination of the organs of circulation and respiration in the proteus,
sirena, and above mentioned larvce, conclude, that the proteus anguinus
is not an amphibious animal, with a double circulation, as many have
asserted, but a perfect reptile, entirely differing from all others,
inasmuch as it is a reptile in respect of its simple circulation, and a
fish in respect of its modeof breathing ; in other words, it is a reptile
which in breathing inhales air mixed with water, whereas other rep-
tiles breathe atmospheric air ; so that if we adopt the notion of a
chain of beings, the proteus anguinus would be the link uniting rep-
tiles with fishes. As the proteus is an animal which breathes only in
the water, and as its branchial circulation can be regarded only as a
minute part of its general circulation, it follows that it consumes
less oxygen than fishes. Hence the quantity of blood which is de-
carbonized in its branchiae, within a given space of time, must be
much less than that which, under similar circumstances, is decarbo-
nized by fishes. This accounts for its inertness, its slow growth, its
power of fasting longer than any other animal of its class, the fluidity
of its blood, and its capability of living in stagnant water, where a
fish of its size would die.

FISHES.

§ 185. Instead of lungs, this class of animals is furnished
■with gills or branchice ; which are placed behind the head, on
both sides, and have a moveable gill-cover, {operculum bran-
cliiale) which is wanting in the order oi jpisces chondropterygii
only. By means of these organs, which are connected with
the throat, the animal receives its oxygen from the air contain-
ed in the water ;* as those animals which breathe, derive it
immediately from the atmosphere. They afterwards discharge
the water through the branchial openings {aperturce bran-
duales) ; and therefore they are distinguished from animals of
the three preceding classes by this circumstance ; viz. that they
do not respire by the same way that they inspire.

§ 186. We have already shewn how the gills receive the
venous blood by means of the branchial artery, and how this
blood is sent into the aorta after its conversion into the arte-
rial state. The distribution of these vessels on the folds and

* Vide Dumeril, on the mechanism of respiration in fishes, in the Magazin, Ency-
clopedique, by Millin, 1807, vol. vi. p. 35.

ON THE ORGANS OF RESPIRATION. 185

divisions of the gills constitutes one of the most delicate and
minute pieces of structure in the animal economy.*

Each of the gills consists, in most fisheSj-f- of four divisions,
resting on the same number of arched portions of bone or car-
tilagCj connected to the os hyoides. Generally there is only a
single opening for the discharge of the water ; but in many
cases, particularly among the cartilaginous fishes, there are se-
veral openings.

§ 187. Many animals of this order possess a single or dou-
ble swimming bladder, J which in the fresh-water fishes of this
country, (Germany) contains azotic gas ; and in salt-water
fishes, chiefly carbonic acid gas. It has not been hitherto de-
termined, whether it be subservient to any other functions,^
besides that well known one, from which its name is derived.
In the mean time, like the air-receptacles of birds it may be
considered without impropriety in the present division of the
work.

It is placed in the abdomen, and closely attached to the
spine. It communicates generally with the oesophagus, and
sometimes with the stomach, by a canal {ductus pneumaticus)
containing, in some instances, as the carp, valves which seem to
allow the passage of air from the bladder, but not to admit its
entrance from without.

The air-bladder does not exist in many fishes ; whence Cuvier ar-
gues with justice against the opinion which assigns this part an im-
portant office in respiration. Indeed it seems much more probable

* Fischer's Xaiurhütor, Fragmente, vol. i. p. 213.

f It is represented by Monro, in the haddock and salmon, tab. 25 and 26.

J See Gott. Fischer über die Schwimmblase der Fische. Leipzig, 1795, 8vo. ; and
additions to it in his Naturhistor. Fragmente, vol. i. p. 229, &c. In both these works
he delineates the bladders of several fishes. Representations of several others may
be seen in Needham De Formato Fcetu, tab. 7. Redi, De Viventibus intra Viventia,
tab. 3, 6 j and the Obs. Anat. Collegii privati Amstelod. pt. 2, tab. 10.

§ Consult Aug. W. Zachariii's Elemente der Luftschwimmkunst. Wittenb. 1807,
p. 90.

On the remarkable connexion with the organ of hearing, vide E. H. Weber De
aure Animalium cujuatilium. Lips. 1820, 4.

186 ON THE ORGANS OF RESPIRATION.

that it is subservient to the motions of the animal. For it is lar-
gest in such fishes as swim with considerable velocity. It is want-
ing in the flat fishes ; where the large lateral fins supply its place, and
in the shark, where its absence is compensated by the size and strength
of the tail. It does not exist in the Inmprey, which possesses none of
these compensations for its absence ; that fish therefore creeps slowly
at the bottom of the water.

It is found in some species of scomber : while others want it, viz.
the mackarel [scomber scombrus). Its form is infinitely varied in the
different genera and species. Its cavity is generally uniform ; but
sometimes divided by septa, as in the silurus ; and being even very
cellular in the diodon.

Its sides vary considerably in thickness, and are sometimes bony,
as in the cobitisfossilis.

There is generally a vascular and glandular body situated in the
cavity, which probably secretes the contained air. In the perca (abrax
are two bodies on the outside of the bag, giving rise to several ves-
sels, which contain air. These vmite together, and open into the ca-
vity.

INSECTS.

§ 188. That white-blooded animals indispensably require a
species of respiration, would have been inferred by analogy
from the wonderful apparatus of gills or tracheae, which have
been discovered in most orders of both classes of these beings.
But in many cases direct proof has been obtained on this point :
experiment has actually proved the exchange of carbon for
oxygen.*

White-blooded animals are moreover distinguished from
those which have red blood, by this circumstange, that none
of the former, as far as we hitherto know, take in air through,
the mouth.

§ 189. Many aquatic insects, -f* as the genus cancer, have a
species of gills;|: near the attachment of their legs. The others,

■ • See the two following very valuable works, F. L, A. Sorg, Disquisitio Physiolo-
gica circa Respirationein Inscctorutn et Vermium ; and Fr. Hausmann, Tentamen solu-
tionis a Societat. Reg. Sciential', Getting, circa Respirationem Insectorum propositee
Questioriis,

t I. F.' Martinet De Respiratione Insectorum, Lugd. Batav. 1753-4.

X They are represented in the crawfish by Willis, De Anima Brutorum, tab, 3, fig. 2
and 3 ; and in Rosel'S Insectenbelustigungen, part iii. tab. 58, fig. 9, 11, tab. 59, fig.
17 ; and in G. Succow, Specimen MyologioB Insectorum, tab. 1, fig. 1.

ON THE ORGANS OF RESPIRATION. 187

and particularly the land-insects, which constitute, as is well
known, by far the greatest number of this class of animals, are
furnished with air-vessels or tracheae, which ramify over most of
their body.* These tracheae are much larger and more numer-
ous in the larva state of such insects as undergo a metamor-
phosis (in which state also the process of nutrition is carried
On to the greatest extent) than after the last, or, as it is called,
the perfect change has taken place.

In this class of animals the scorpions, being also provided
with fins, present an extraordinary instance of an animal,
which, though living nearly in the air, breathes like fishes.+

§ 190. A large air-tube (trachea) lies under the skin on each
side of the body of larvae, and opens externally by nine aper-
tures {stigmata): it produces on the inside the same number of
trunks of air-vessels, {branchicE) which are distributed over the
body in innumerable ramifications.^

Both the tracheae and branchiae are of a shining silvery co-
lour ; and their principal membrane consists of spiral fibres.
The most numerous and minute ramifications are distributed on
the alimentary canal ; particularly on the above-mentioned
corpus adiposum.

§ 191. There is a great variety in the number and situa-
tion of the external openings by which insects receive their
air.§

* Cart. Spreyel De partibus quibus insecta spiriium ducunt. Leips. 1815.

f Treviranus über den innern Bau der Araclmiden. Numb. 1812,

X Lyonet Anatomie de la Chenille, &c. tab. 4, 5, 6, 7, 10, and 11. The same
organs have been represented by Swammerdam, in the scarabceus nasicümis, tab. 29,
fig. 9, 10, tab. 30, fig. 1, 10. In the lucanus cervtis (stag-beetle) by Malpighi, De
Bomhyce, tab. 3, fig. 2 ; in a cicada, ibid. fig. 3. In a gryllus, (grasshopper) ibid.
tab. 4, fig. 1 ; also by Cuvier, in the Mem. de la Soc. d'Hist. Naturelle de Paris, an
7, p. 39. In the silk-worm by Malpighi, tab. 3, fig. 1. In a libellula by Cuvier,
in the work just quoted, fig. 2, 5, 6, In the E-phemera by Swammerdam, tab. 14,
fig. 1, tab. 15, fig. 1, 4, 7. In the bee, ibid, tab. 17, fig. 9, 10, tab. 25. fig. 10,
tab. 24, fig. 1, 2, 3. In the otstrus bovis, by Mr. B. Clark, in the Transact, of the
Linno'an Society, vol. iii. tab. 23, fig. 25. In the maggot of the fly by Swammerdam^
tab. 40, 41, 42, 43. In the louse, ibid, tab. 1, fig. 8, 4, 7.

$ See the work above quoted, by Hau9»mann.

ISS ON THE ORGANS OF RESPIRATION.

In most instances the stigmata are placed on both sides of
the body. The atmospheric air enters by an opening at the
end of the abdomen in several aquatic larvae, and even perfect
insects. A very remarkable change in this respect takes place
in several animals of this class during their metamorphosis.
Thus in the larva of the common gnat, {culex pipiens) the air
enters by an opening on the abdomen ; while in the nympha
of the same animal, it gains admission by two apertures on the
head.*

VERMES.

§ 192. In this class, which comprehends such very different
animals, the structure of the respiratory organs is proportion-
ally various.t Some orders, as those which inhabit corals,
the proper zoophytes, and perhaps the intestinal worms, ap-
pear to be entirely destitute of these organs ; so that if any
vital function, analogous to respiration, is carried on in these
animals, it must be effected by methods which yet remain to
be discovered.

§ 193. Those vermes, however, which are furnished with
proper organs of respiration, have the same variety in their
structure which was remarked in insects. Some, as the cuttle-
ßsJi,X oyster,% &c. have a species of gills, varying in structure
in different instances. But the greatest number have air-ves-
sels or tracheae.!! Several of the testaceous vermes have both

* Swammerdam, Algem, verhandel. Van de Bloedeloose Bierkens, tab. 2.

f The reader may consult on this subject Cuvier, in the Journal d'Histoire Na-
turelle, 1792, torn, ii, p. 85 ; and in his Tableau d'Histoire Naturelle des Animaux,
p. 384 ; also Sorg and Haussmann, in their works quoted above. And Spallanzani
Memdres sur la Respiration. Geneve, 8vo. 1803.

i Swammerdam, Biblia Natures, tab. 51, fig. 1. Monro, tab. 41, fig. 1. And
particularly Dr. C. F. G. Tilesius De Respiratione Sepia Officinalis. Lips. 1801-4,
tab. 1, 2.

§ Willis, tab. 2.

II Examples of this structure in testaceous vermes may be seen in the lepas balanus,
(acorn-shell) Poll, tab. 4, fig. 20, 22. In the pholas dactylus, (pierce-stone) ibid,
tab. 8, fig. 61. In the solen strigilatus, (razor-shell) tab. 13, fig. 5. In the helix po-
matia, (snail) Swammerdam, tab. 4, fig. 1,

The

ON THE ORGANS OF RESPIRATION. 189

kinds of respiratory organs. In some of the inhabitants of bi-
valve shells, as the genus Venus* the air-vessels lie between
the membranes of a simple or double tubular canal, found at
the anterior part of the animal, and capable of voluntary ex-
tension and retraction. It serves also for other purposes, as
laying the eggs. The margins of its mouth are beset with the
openings of the tracheae.

In the terrestrial gasteropodous mollusca, of which we may in-
stance the snail and slug, there is a cavity in the neck receiving air
by a small aperture, which can be opened or shut at the will of the
animal. The pulmonary vessels ramify on the sides of the cavity.

The common slug affords an instance in the mollusca, see Swammerdam, tab. 8
fig. 7, tab. 9, fig. 1, and the leech in the intestinal worms, Bening De Hirudinihus,
p. 20 ; and P. Thomas, Histoire Naturelle des Saiigsues. Par. 1306.

* In the Venus lata, Poli, tab. 2, fig. 17.

190

CHAPTER XV.

ON THE ORGAN OF THE VOICE.

^ 194. Aristotle has correctly observed, that those animals
only, which possess lungs, consequently the three first classes
of the animal kingdom, possess a true voice. Several genera
and species even of these are either entirely dumb, as the ant-
eater, the manis, the cetacea, the genus testudo, several lizards
and serpents ; or they lose their voice in certain parts of the
earth ; as the dog in some countries of America, and quails*
BXidLfrogs-^" in several parts of Siberia.

In a preparation — a dried one indeed — of the larynx and
lungs of the two-toed ant-eater, I find the larynx entirely bony,
that is, of the same substance with the os hyoides. The tra-
chea, which is extremely short, is a merely membranous canal,
without any perceptible trace of cartilaginous rings. J. Hunter
found no thyroid gland in the whales, which he dissected.
This coincides with the hypothesis upon which this gland is
supposed to be connected with the formation of the voice.

MAMMALIA.

§ 195. Most animals of this classj have the following cir-

* Pennant's Arctic Zoology, torn, ii. p. 320.

t MuUer's Sammlung Russischer Geschichte, vol. vü. p. 123. J. C. Beckmann's
Historische Beschreibung der Chur und Mark-Brandenburg, vol. i. p. 590.

:{: Besides the two old and highly valuable works on the organ of the voice, by
Casserius and Fab. Ab Aquapendente, and the writings which we shall have occa-
sion to quote in the sequel, I refer the reader to M. J. Busch, Dissei't. de Mechanismo
Organi Vocis. Groning. 1770, 4to. which contains several excellent observations by

ON THE ORGAN OF THE VOICE. 1^1

cumstances in common ; their rima glottidis is provided with
an epiglottis, which in most instances has a peculiar muscle,
arising from the os hyoides, and not found in the human sub-
ject : the margins of this rima are formed by the double liga-
menta glottidis {ligamenta thyreo-arytcenoidea); between which
on each side the ventriculi laryngis are situated. The epiglot-
tis does not exist in most of the bat kind ; and in some mouse-
like animals, as the rell-mouse, (glis esculentus) it is hardly
discernible. The superior ligamenta glottidis, as well as the
ventriculi laryngis are wanting in some bisulca, as the ox and
sheep.

§ 196. Some species of mammalia have a peculiar and cha-
racteristic voice ; or at least certain tones, which are formed
by additional organs. Thus there are certain tense mem-
branes in some animals ; and in others peculiar cavities, open-
ing into the larynx, and sometimes appearing as continuations
of the ventriculi laryngis, which are destined to this purpose.

The neighing of the horse, for example, is effected by a de-
licate, and nearly falciform membrane, which is attached by
its middle to the thyroid cartilage, and has its extremities run-
ning along the external margins of the rima glottidis.*

The peculiar sound uttered by the ass is produced by
means of a similar membrane ; under which there is an exca-
vation in the thyroid cartilage. There are moreover two large
membranous sacs opening into the larynx.t

The mule does not neigh like the mare, by which it was
conceived ; but brays like the ass which begot it. It possesses
exactly the same larynx as the latter, without any of the pecu-
liar vocal organs of the mother : a fact which, like many others,

Camper. See also L. Wolf, Diss. Anatotnica de Organo Vocis Mammalium. Berol.
1812. On the peculiar structure of this organ in eetacea, see Camper Sur la
Structure Interieure de plusieun enlaces. Albers's Icones, fasc. 2 ; and Rudolphi, in
the Abhandlung der Berlin, Akad physik. 1820.

* Herissant in the M^m. de I' Acad, des Sc. 1753, tab. 9.

t Ibid. tab. 10.

192 ON THE ORGAN OF THE VOICE.

cannot be at all reconciled with the supposed pre-existence
of previously formed germs in the ovarium of the mother.

I have adduced this essential, and really specific difference
in the structure of the larynx of the horse and ass: as one of
the many arguments which overthrow the rule adopted by
Ray, BufFon, and others, of ascribing to one and the same spe-
cies all such animals as produce by copulation an offspring
capable of subsequent generation.*

The cat has two delicate membranes lying under the liga-
menta glottidis ; which probably cause the purring noise pe-
culiar to these animals. +

The jiig has two considerable membranous bags above and
in front of the ligamenta glottidis.J

Several apes\ and baboon'i, || as also the reindeer, have
on the front of the neck large single or double laryngeal sacs,
of various forms and divisions, communicating with the larynx
by one or two openings between the os hyoides and thyroid
cartilage.

In a common ape {simia sylvanus) I found the right laryn-
geal sac three inches long, and two inches in circumference;
while the left was not larger than a nutmeg. The larynx of
the simia cynomolgus may be seen in Camper's account of that
animal.^

Some of the cercopitheci, as the cercopithecus seniculus,
and Beehebub, have the middle and anterior part of the os hy-
oides formed into a spherical bony cavity,** by which the ani-

* See Gore's Translation of BlumenhacKs Manual History, p. 8.

t Vicq d'AzjT, in the Mem. de I'Acad. des Sciences, 1779, tab. 11, fig, 17.

t Casserius De Vocis Auditusque Organis, tab. 11, fig. 9, 10, p. 55, ad grunni-
tum in porcis efficiendum. Herissant, loco citato, tab. 11.

§ As the oraug-outang. See Camper's Natural History of that animal — the simia
inuus, see Ludwig's Grundriss der Naturgeschichte der Menschenspecies.

II It is represented in the mandrill, (papio maimon') by Vicq d'x\zyr, loco citato.,
tab. 7.

51 Camper, loco citato, tab. 8, fig. 7.

** Vicq d'Azyr, loc. cit. tab. 9, 10. Camper, tab. 4,

ON THE ORGAN OF THE VOICE. 193

mals are enabled to produce those terrific and penetrating
tones, which can be heard at vast distances, and have gained
them the name of the howhng apes.

The larynx of mammalia is generally of the same conformation as
in man. None of the large cartilages of the larynx are deficient, and
the opinion that some animals of this class want the epiglottis is
quite erroneous. In several, as the bat for instance, it is extremely
small. The size of the larynx is proportionate to the strength of the
sounds which the animals utter. The absolute size of the larynx
of the wliale and the elephant is the largest, but relatively the la-
rynx of the lion has a still greater circumference. The cartilages
vary in their form ; in the cercopitheci seniculi the os hyoides is di-
lated to a large bony pouch, and the thyroid cartilage at the same
time bent forwards, which explains the deafening noise which they
emit. In some animals, as the antelope gutturosa, there is a dilatation of
the thyroid cartilage, and in some there are fleshy appendices, or air-
sacs, which have their exit from the ventricles of Morgagni, or below
the epiglottis, and therefore are sometimes single and at other times
double. The apes of the old world have these sacs, and the orang-
outang has them doubled ; in others, as the green ape, they are sin-
gle ; this is also the case in the reindeer. In reality the depressions
of the ventricles in the pig, or above the thyroid cartilage, as in the
horse and kangaroo, may be regarded as the incipient state of this
structure.

In most mammalia the number and situation of the vocal ligaments
are the same as in man. The trachea in long-necked animals, is natural-
ly much lengthened, and the number of rings increased ; in men there
are from seventeen to twenty in number, whereas in the camel there are
seventy-four ; in the stag, fifty- three ; in the bullock, fifty-two ; in the
domestic mouse, there are from fourteen to fifteen ; in the hedgehog,
eighteen ; in the rat, twenty-one ; in the beaver, twenty-two ; in the
cercopithecus seniculus, twenty-four ; in the bear, twenty-eight ; in the
hyOEnu, thirty-six ; in the lion, cat, dog, and rabbit, thirty-eight ; in
the hog, from thirty-eight to forty ; in the lynx and guinea-pig, forty ;
in the hare, forty-four ; in the wolf, otter, and sheep, fifty ; in the roe^
sixty- three ; in the ferret, sixty-seven ; in the seal, seventy-eight. In
many animals, as in the cercopithecus seniculus, lion, and bear, the space
between the end of the rings is very great, so that the trachea can be
very considerably narrowed, which structure contributes to the inten-
sity of the sounds they are capable of emitting. In the hywna the ex-
tremities of the rings of the trachea lap over each other, and are also
capable of being much compressed ; a structure which probably oc-
casions the peculiar cry of that animal. In a few mammalia the tra-
cheal rings are closed : entirely so in the beaver, and in the upper part
of the trachea in the seal. The muscles and nerves of the larynx pre-
sent in mammalia little variation from those of the human subject, ex-

o

194 ON THE ORGAN OF THE VOICE.

cept that in many animals those of the epiglottis are fully developed,
whereas in man they are very indistinct. See Rudolphi's Grund'
riss der Physiologie, vol. ii. part 1 , p. 380 ; to which excellent work we
are indebted for much of the additional matter inserted in this edition.

BIRDS.

I 197. The most striking peculiarity in the vocal organs of
this class, a peculiarity which belongs to all birds with a very
few exceptions, consists in their possessing, what is commonly
called, a double larynx, but which might be more properly de-
scribed as a larynx divided into two parts, placed at the up^^
per and lower ends of the trachea. They have also two rimae
glottidis.

§ 198. The superior or proper rima glottidis is placed at
the upper end of the trachea, but is not furnished with an epi-
glottis.* The apparent want of this organ is compensated in
several cases by the conical papillae placed at both sides of the
rima.

I 199. The apparatus, which is chiefly concerned in form-
ing the voice of birds, is found in the inferior or bronchial la-
rynx. Hence the division of the trachea below the upper rima
glottidis scarcely produces any change in the voice of several
birds, as they can still utter sounds by means of the bronchial
larynx.*!* This larynx contains a second rima glottidis, formed
by tense membranes ; which may be compared in several cases,
particularly among the aquatic birds, to the reed pipes of an
organ. It is furnished externally with certain pairs of muscles,
varying in number in the different orders and genera ; and
with a kind of thyroid gland. The course and proportionate
length of the trachea, and particularly the structure of the in-

* The part which Warreu has described in the 34th vol. of the Philos. Trans, p.
1 13, as the epiglottis of the ostrich, is merely a slight elevation at the root of the
tongue. See Cuvier, in the Menagerie du Museum National d'Histoire Naturelle,
No. 1, tab. 3.

t See Duverney, in the Hist, de I'Acad. des Sciences, torn. ii. p. 7. Girardi, in
the Memorie delta Societa Italiana, torn. ii. pt, ii, p. 737 ; and Cuvier, in the Mst^a-
zin Encyclopidique. Arm. i. torn. ii. p. 357.

ON THE ORGAN OF THE VOICE. 195

ferior larynx, vary very considerably* in the different species,
and even in the two sexes, especially among the aquatic birds.
Thus, for example, the tame or dumb swan (anas olor) has a
straight trachea, whilst in the male of the wild or whistling
swan, (cygnus) this tube makes a large convolution, which is
contained in the hollow of the sternum (see § 56). In the
spoonbill (platalea leucorodia) as also in the phasianus motmot^
and others, similar windings of the trachea are found, not in-
closed in the sternum. In many swimming birds the males
have at their inferior or bronchial larynx a bony cavity, the
form of which varies in different species,+ and which contri-
butes to strengthen their voice.J

" A very little comparison of the mechanism of wind musical in-
struments with the organs of the voice in birds will shew how nearly
they are allied to each other ; and it may be observed, that the sound
produced by some of the larger birds is exactly similar to the notes
that proceed from a clarionet or hautboy in the hands of an untu-
tored musician. The inferior glottis exactly corresponds to the reed,
and produces the tone, or simple sound. The superior larynx gives
it utterance, as the holes of the instrument ; but the strength and
body of the note depend upon the extent and capacity of the tra-
chea, and the hardness and elasticity of its parts. The convolution
and bony cells of the windpipe, therefore, may be compared with the
turns of a French horn and the divisions of a bassoon ; and they pro-
duce the proper effects of these parts in the voices of those birds in
which they are found." Rees's Cydopadia, art. Birds.

* On the subject of the bronchial larynx, the reader may consult Herissant,
"Vicq d'Azyr, and Cuvier, in their works already quoted : also another dissertation
by the latter author in the 2nd vol. of the fourth year of the Magazin Encyclopedique.
Schneider, in the Leipsig Magazine for 1786 and 1787, and in his valuable Commen»
tary on the Works of Frederic II. pp. 32, 211.

Aldrovandi has described that of the wild swan. Ornitholog, torn. iii. p. 13.

That of the goose has been most excellently described by Haller De partium corp,
humani fahrica et functionibus, torn. vii. p. 321, which may be compared with the
beautiful delineations of Herissant, lac. citat. tab. 12,

t Besides Herissant and C!uvier, loc. citat. the reader may consult Aldrovandi,
OrnitfwL torn. iii. p. 190. Wilioughby, Ornithol. tab. 73. Bloch, in the Beschüße
der Berliner Naturf. Gesellsch. Berlin, torn. iv. p. 579, tab. 16 ; and in his works,
torn. iii. p. 372, tab. 7. Latham, in the Transactions of the Linna-an Society, vol. iv.
p. 90, tab. 9, 16.

} See Fabricius Hildanus, Beschreibung der Fürtrejßichkeit der Anatomie, p. 323.

o 2

196 ON THE ORGAN OF THE VOICE.

The larynx of birds is divided into an upper and lower, and the
lower forms tlie proper organ of voice. At the point where the.
lowest bony ring of the trachea branches off to form the bronchia,
the skin folds on itself, and constitutes at the opening of each bron-
chus an elastic membrane, which projects into it, somewhat analogous
to the vocal ligaments in mammalia. In the parrot tribe this division
does not exist, and consequently there is not a double rima glottidis,
as in other birds provided with vocal organs. Cuvier could not find
this membrane in the vuUur papa ; and Rudolphi, who had an op-
portunity of examining this vulture, as well as the vultur aura, was
unable to discover it. Singing birds have five pairs of muscles, and
the parrots three, which are attached to the semi- circular rings of the
divisions of the trachea, and relax or tighten the rimae glottidis.
Birds which utter a single cry, as the accipitres and many aquatic
birds, have only one such pair of muscles ; other aquatic birds and the
galliiiw have none. Cuvier has admirably proved in living birds that
this lower larynx is the proper organ of voice ; he divided the tra-
chea above the lower larynx, and closed the upper part of it. The irri-
tated animal emitted by the lower larynx its accustomed sounds in a
weaker tone; the same sounds were emitted when he removed the
whole neck. The parts analogous to the cartilages of the larynx in
man are very small in birds, and in structure bear a greater resem-
blance to bone. In most birds they lie close behind the tongue and
the OS hyoides, and form the commencement of the trachea. The
fissure which they form, and which is not protected by an epiglottis,
is opened by one pair of muscles, and closed by another. It merely
serves for the passage of the air, being the commencement of the
organ of respiration.

The trachea presents in many birds very remarkable diflPerences.
In some gallinaceous birds it makes a great curve before the sternum,
as in the crax and penelope. In the urogallus (cock of the wood) this
curve takes place in the neck ; in the crane and anas cygnus in the
keel of the sternum. In many aquatic birds as the anas clangula,
fusca, &c. the trachea is considerably dilated in one or more places.

In general the great development of the vocal organs is peculiar to
the male; as, for instance, the curve external to the sternum, the
osseous bladders of the trachea, and of the lower larynx ; the greater
curvatures in the keel of the sternum occur in both sexes ; in males,
however, they are stronger.

AMPHIBIA.

§ 200. The structure of the vocal organs in this last class
of animals, which possess a voice, is on the whole very simple ;
although it varies in several genera and species, and sometimes
in the two sexes.

§ 201. The tortoises^ (at least the testudo grceca) may be

I

ON THE ORGAN OF THE VOICE. 197

said to have two tracheae : for the short common trunk divides
at the third cervical vertebra into two long branches, which
descend far into the chest before they enter the lung. Each
of them makes a large lateral cvirvature, over which the two
'aort(JB abdominales bend their course.* It is very short in the
frog ; but longer in the male than in the female : the rima
glottidis is also larger in the former. Ligamenta glottidis
exist in all the animals of this class.-f-

§ 202. The males of some frogs are distinguished by pecu-
liar air-bags. The tree-frog {rana arborea) has a large sac
in its throat; and the green frog {rana esculenta) has two
considerable pouches in the cheeks, which it inflates at the
time of copulation by two openings close to the rima glot-
tidis.l

All amphibia have the opening of the larynx without an epiglottis,
and the cartilages which form the larynx are very analogous to those
of the upper larynx of birds. Frogs, and some of the lizards, possess
a structure similar to the vocal ligaments. In the ixma pipa Rudol-
phi found a very curious structure : in the male the larynx was com-
posed of two laminae of bone, compressed from above downwards,
of about ten lines in length, seven and a half lines broad at the
base, and six and a half in the centre. In the female it was smaller,
and merely cartilaginous. The bronchi proceed from the larynx
directly backwards, being very short in the male, and long in the
female. In the gecko fimbriatus Tiedemann (Meckel's Archiv, iv. s.
549) discovered in the trachea immediately below the larynx a dila-
tation half an inch long, and three lines broad, which he supposes to
be of service to the animal when under water ; for it has been
asserted that this gecko lives several months in the year in fresh
water at Madagascar, though Rudolph! thinks this very improbable,
since its structure has not the remotest resemblance to that of an
aquatic animal. This learned naturalist considers it, from analogy
to birds, of use in strengthening the organs of voice, as in the -pipa ;
and this opinion is confirmed by the circumstance of another gecko
(the toc-kai of Siam) being distinguished for its discordant cry.

* Blazii, Zootomia. Amst. 1677, 8vo, tab. 17, fig. 5.

t Vicq d'Azyr, loc. citat. tab. 13, fig. 45, 46, represents these fragments in the
testudines, fig. 41, 42, 44, in frogs, fig. 47, 52, in serpents.

The larynx of the rattlesnake is represented in Tyson's Anatomy of a Rattlesnake,
Philoi. Trans, vol. xiii. No. 144, fig. 5.

X See Camper's Kleine Schriften, vol. i. part i. p. 144, tab. I?, fig. 1, 4.

198 ON THE ORGAN OF THE VOICE.

A very shrill sound is uttered by frogs, especially the hull-frog
(rana ocellafa). Whether the singing-bladders, as they are termed,
of the green frogs of Germany, assist them in uttering this sound,
as P. Camper thinks, {Kleine Schriften, vol. i. s. 141, 150) is stilt
a matter of great doubt ; since these structures do not commu-
nicate with the larynx, but only with the mouth. According to
Humboldt, {Obs. zur Zoologie, vol. i. p. 11) young crocodiles utter a
sound similar to that of cats ; but he never heard any cry proceed
from the old ones. Most lizards, all the testudines, and tailed tad-
poles are dumb. This is also the case with serpents, since their
hissing cannot be called a true voice. (Rudolphi Grunäriss der Phy-
siologie, vol. ii, p. 387.)

One exception to the last observation of Rudolphi will suggest
itself to the reader ; but it may be doubted whether, even before
the Fall, serpents were endowed with the gift of speech. Dr. Bur-
net, in his ArehaologicE Philosophicee, rejects the Mosaic account of
the dialogue between Eve and the serpent, not indeed as fabulous,
but as fictitious or parabolical ; and the silence of the physio-
logist is excused, therefore, by the scepticism of the divine. Be-
stiavi Mam loqui posse, says Dr. Burnet, aut quacumque voce prater
$ibila nondum scimus. At quid de ea re scivisse Evam credemus ?
Si pro muto animali hahiiisset, ipsa loquela terruisset fceminam, et
ab omni sermonis commercio pepulisset. 2iiod si loquax fiiit, et ser~
viocinator ab initio serpens, perdiditque loquelam ob hoc facinus quod
pietatem fidemque Evce suis blanditiis corruperat, hoc genus pcence neuti-
quam tacuisset Moses; neque levius damnum de lambendo pulvere ipsius
loco substituisset. Prmterea vis unicum serpentum genus, vel omnes
hestias a'^ri vocales fuisse in Paradiso \ ut olim arbores in nemore
DodoncEo ? Si omnes, quid commisere ceeteree ul mum lingua per-
derent ? Si unicum serpentum genus hoc gaudebat privilegio ; fcedum
(inimal et ab humana specie alienissimum qui potuit 7nereri pra aliis
omnibus, sermonis gratiam et beneficium ? " We know not whether
the serpent had naturally the faculty of talking, or of producing
any sound, beyond the hissing noise which is all it can achieve in
these days. What shall we suppose Eve to have known about this
matter ? If she considered it a dumb animal, the very circumstance
of its entering into conversation with her must have alarmed a timid
female, and deterred her from continuing so monstrous an inter-
course. But if the serpent talked at its creation, and lost the gift of
speech for its wickedness in corrupting Eve, Moses would not have
failed to mention this punishment, nor would he have substituted
in its place the lighter inconvenience of being condemned to lick the
dust. Again, will it be contended that the race of serpents alone,
or that all beasts had the gift of speech in Paradise, like the talking
trees in the grove of Dodona 1 If they all talked, what have the
rest done that they too should lose the gift of speech ? If serpents
alone enjoyed this privilege, how shall we account for this distinc-
tion having been specially conferred upon an animal of such a nasty
description, and so utterly unlike the human species?"

ON THE ORGAN OF THE VOICE. 199

Dr. Burnet, while he admits with philosophical candour that the
whole of the Mosaic account of the creation might be regarded as fa-
bulous, if found in a profane writer, and while he exposes the ab-
surdities involved in a literal interpretation of the Jewish cosmogony
with an air of pleasantry which might be mistaken for ridicule in a
less pious inquirer, acknowledges at the same time the divine inspi-
ration of Moses, and expresses a laudable indignation at the impiety
of those who have treated the sacred narrative with disrespect.
Succensere non possum, says the divine, ex Pairibus et auctoriOus an-
tiquis Ulis, qui in symbola aut parabolas aut sermones populäres hcEc
converiere stiiduerunt. Succenseo autem Celso, qui aniletn fabulam,
f*t;6ov 'r^va, u<; y^^^vav Siviyovjji.evov, hanc narrationem appellat. Ubi recte
monetfper moduin responsi Origines, St* /xera T^owoXoyias ravTa n^-nrxi.
" I cannot be displeased with those Fathers of the church, and other
ancient writers who have treated the Mosaic account of the creation
as a popular story or parable, but I am undoubtedly displeased with
Celsus, who has called it an old woman's story, which imputation
Origen has satisfactorily answered by observing that these things are
to be understood tropically" Dr. Burnet's Archceologice Philosophicce,
lib. ii. cap. 7.

THE ANIMAL FUNCTIONS.

THE ANIMAL FUNCTIONS.

CHAPTER XVI.

ON THE BRAIN AND NERVOUS SYSTEM IN GENERAL.

§ 203. 1 HIS class of functions which constitutes the leading
character of animals, and has derived its name from that cir-
cumstance, affords to our observation a more clear and mani-
fest gradation, from the most simple to the most compound
structure, than any others in the animal economy.*

§ 204. In some of the most simple animals of the class
vermes, particularly among the zoophytes, little or no distinc-
tion of similar parts f or structures can be discerned ; and we
are unable to recognize any thing as a particular nervous
system, or even as a part of such a system. The power of
sensation and voluntary motion, which these possess, as well

• An ingenious attempt to establish a new classification of animals, according to
the general organization of the nervous system, has been made by Rudolphi, in his
Beytriige zur Anthropologie und allgemeine Naturgeschichte. Berl. 1812, p. 79.

Much instructive information on this subject, particularly with reference to the
brain of warm-blooded animals, will be found in Gall and Spurzheim's Anatomie et
Physiologie d'j, Systeme Nerveux. Par. 1810, 4to.

See J. and C. Wenzel De structura cerebri humani et hrulorum. Tubing. 1812,
fol. ; and several other works on this subject, which I have enumerated in the fourth
edition of my Inslitutiones Physiologic^ , 1821, p. 176.

t By the term partes similares, the ancients denoted those homogeneous organic
structures which form nerves, muscles, tendons, bones, cartilages, &c. ; the combi-
nation of which constitutes the partes dissimilares of the animal body, i. e. the limbs,
viscera, &c.

204 ON THE BRAIN AND NERVOUS SYSTEM.

as any other order or class of the animal kingdom, prove that
the nervous matter must be uniformly spread throughout their
homogeneous substance. The almost transparent polypes,
{Jiydroe) which are often found in this country, (Germany) with
a body of an inch in length, and arms, or tentacula, of a
proportionate size, appear to consist, when surveyed in the
best light by the strongest magnifying power, of nothing but
a granular structure, (something similar to boiled sago) con-
nected into a definite form by a gelatinous substance.

§ 205. In many other vermes, and in insects, a ganglionic
system of nerves can be distinguished, arising in general from
what is called the spinal marrow, the superior extremity of
which part, slightly enlarged, constitutes the brain. The lat-
ter organ, however, in both classes of cold and red blooded
animals, and still more in those which have warm blood, has ä
much more complicated structure, and a far greater relative
magnitude : all animals are hoAvever exceeded in both these
points by the human subject, which, according to the inge-
nious observation of the learned Sömmering,* possesses by
far the largest brain in proportion to the size of the nerves
which arise from it.

The small size of the brain in proportion to the rest of the
nervous system has a very considerable influence on the whole
animal economy of cold-blooded, when viewed in comparison
with warm-blooded animals. It explains the diminished sym-
pathy between the two parts; and the consequently weak powers
of motion in their whole machine. It enables us also to under-
stand the remarkable independence of the vitality of their
parts upon that of the brain, and their possession of consider-
able individual powers of life, as also the extraordinary extent
of their reproductive powers.*!'

* See his Bhtertatio de hau Encephali. Goetting. 1778, p. 17; and his Tabula
baseos Encephali. Francof. 1799, p. 5; also J. G. Ebel, Observ. Neurol, ex Anatome
comparat. Francof. ad Vadrum, 1788.

t I have treated at greater length on all these points in my Specimen Physiologi<s
comparatCE inter Animantia calidi et frigidi Sanguinis, in the 8th vol. of the Goettin-
gen Commentaries ; and in the Handbuch der Naturgeschicte, p. 225.

ON THE BRAIN AND NERVOUS SYSTEM. 205

The vast superiority of man over all other animals in the faculties
of the mind, which may be truly considered as a generic distinction
of the human subject, led physiologists at a very early period to seek
for some corresponding difference in the brains of man and animals.
They naturally investigated the subject in the first instance, by
comparing the proportion which the mass of the brain bears to the
whole body ; and the result of this comparison in the more common
.and domestic animals was so satisfactory that they prosecuted the
inquiry no further, but laid down the general proposition, which has
been universally received since the time of Aristotle, that man has
the largest brain in proportion to his body. Some more modern
physiologists, however, in following up this comparative view in a
greater number of animals, discovered several exceptions to the
general position. They found that the proportion of the brain to the
body in some birds exceeds that of man, and that several mammalia
(some quadrumana, and some animals of the tnouse kind) equal the
human subject in this respect.

As these latter observations entirely overturned the conclusion
which had been before generally admitted, Sömmering has furnished
us with another point of comparison, that has hitherto held good in
every instance : viz. that of the ratio which the mass of the brain
bears to the nerves arising from it.

Let us divide the brain into two parts ; that which is immediately
connected with the sensorial extremities of the nerves, which receives
their impressions, and is therefore devoted to the purposes of animal
existence. The -second, division will include the rest of the brain,
which may be considered as connecting the functions of the nerves
with the faculties of the mind. In proportion then as any animal
possesses a larger share of the latter and more noble part ; that is, in
proportion as the organ of reflexion exceeds that of the external
senses, may we expect to find the powers of the mind more vigorous
and more clearly developed. In this point of view man is decidedly
pre-eminent : here he excels all other animals that have hitherto
been investigated.

The brain of man is much larger than that of the simiae, when
compared with the size of the nerves which proceed from it ; this
may be readily seen by looking at the comparative breadth of the
cerebral nerves and brain in man and different animals. The size of
the brain, as compared with that of the medulla spinalis in man, is
larger than in si?nice, as may be perceived on comparing the trans-
verse diameter of the spinal marrow below the corpora pyramidalia
with the whole breadth of the cerebrum. The size of the brain in
simice and the seal is larger in proportion than in other animals.
The classes of animals whose cerebrum is next in size, are the
lemuies, cetacea, ruminantia, multungula, soüdungula,fer(e, et bradypoda.
The cerebrum is smallest in the glires, marsupialia, edentata, and
chiroptera. The cerebellum of simics presents but few differences
from that in man. In one species, saimiri, it is greater than in

206 ON THE BRAIN AND NERVOUS SYSTEM.

man ; and in a number of instances the ratio is the same or nearly
the same ; for example, in the ox it is the same ; in the cat, various
monkeys, and in the horse, it is nearly the same. (Vid. Warren
on the Sensorial and Nervous Si/stems, ^c. p. 81.)

The researches of Söramering on animals in general have led hira
to conclude that the quantity of brain, over and above that which is
necessary for a mere animal existence ; that part, in short, which is
devoted to the faculties of the mind, bears a direct ratio to the doci-
lity of the animal, to the rank which it would hold in a comparative
scale of mental powers.

The largest brain which Sömmering has found in a horse, weighed
lib. 4oz. ; and the smallest which he has seen in an adult man, was
2 lb. 5| oz. Yet the nerves arising from the former brain were at
least ten times larger than those of the latter.

The following table exhibits the proportions of the mass of the
brain to that of the whole body in man and the different classes of
animals. It will be observed that, cceteris paribus, small animals have
a larger brain, in proportion to their size, than larger ones : that the
brain of man is exceeded, in proportional size, by some few animals,
as mice, the smaller birds, &c. ; that among the mammalia, the roden-
tia have generally the largest, and the pachydermata the smallest
brain ; and that the brain is extremely small in cold-blooded, as com-
pared with warm-blooded animals.

MAMMALIA.

It forms in man from -i-^^ -gJ^, -^^ ^, of the body, according to the
different periods of his life.

Orang'OUtangs,
la the Gibbon ^^^ of the body.

Sapajous (American Apes),

Saimiri -^

Sa'i -2^

Ouistiti ^

Coaita ...... ^

African and Indian Apes.

Malbrouk ^»^

Callitriche and Patras . -^-^
The monk ape .... ^^^
Mangabey ^h

ON THE BRAIN AND NERVOUS SYSTEM.

207

Magots and Macakos.

Macako (simia silenus) . ^ of the body.

Magot .^

Papio t44

Mahis,

Mococo ...... ^*^

Vari ^

Cheiroptera.
Bat *

Plantigrada.

Mole ^

ßear ^I^.

Hedgehog ^

Carnivora.

Tino _1_ I I I I 1

■^"S TT» riy» TT7' TT4» T5T» T5T

Fox ^^

Wolf ^1-^

Cat ■i^>^,r^

Ounce ^^

Pine-martin ^^

Ferret ^

Rodentia.

Beaver ^

Hare ^«^

Rabbit -rb. TTT

Ondatra tJtt

Rat ^

Mouse I

4T

Field-rat ^i^.

Pachydermata.
Elephant -^

l-'Svji^.-.

208 ON THE BRAIN AND NERVOUS SYSTEM.

Wild-boar ^^ of the body.

Chinese hog .... ^-^

Ruminantia.

Stag . ^^^

Roebuck -^-^

Sheep ^^T. tI-j

Ox . ^

Calf ^^^

Solipeda.

Horse 4:!^

Ass ^1^

Cetacea.

Dolphin . . ^, ,-V, -^, T^

Porpoise ^

BIRDS.

Eagle ^^

Sparrow -^

Chaffinch -^y

Redbreast /^

Blackbird -^

Canary-bird .... -^-^

Cock ^V

Duck ...... -jly

Goose -j-g-g-

REPTILES.

Tortoise ^^^^

Turtle ...... ^^V?

Coluber natrix . . . y^^

Frog TT^

FISHES.

Shark ...... ^-/^^

"'ke ttW

ON THE BRAIN AND NERVOUS SYSTEM. 209

Carp ^^^

Dog-fish t^Vt

Tunny ...... ^^^^

Silurus glanis .... ^ttt

The following table shews the proportion of the cerebrum to the
cerebellum in man and other mammalia. The rodentia have the
largest cerebellum in proportion to the cerebrum ; and man has the
least cerebellum in proportion to the cerebrum of all the mammalia.

In man, the cerebellum is to the cerebrum . 1:9

Saimiri 1 : 14

Sai 1:6

Magot . . . 1:7

Papio 1:7

Monk Ape 1:8

Dog 1:8

Cat .1:6

Mole . 1 : 4.5

Beaver 1:3

Rat . 1 : 3.25

Mouse 1:2

Hare 1:6

Wild Boar 1:7

Ox ...1:9

Sheep ...1:5

Horse ..1:7

The proportion of the cerebrum to the medulla oblongata is ascer-
tained by measuring their diameters. Sömmering and Ebel have
shewn that it is greater in man than in other animals, and that it fur-
nishes a good criterion of the degree of intelligence in the individual,
as it shews the relation which the organ of intelligence bears to the
organs of the external senses. There are, however, some exceptions
to this rule, as in the remarkable instance of the dolphin. The fol-
lowing table exhibits the proportions between the breadth of the me-
dulla oblongata at its base, and the greatest breadth of the cerebrum
in some of the mammalia, and in a few birds.

In man, the breadth of the cerebrum is to that of the

medulla oblongata, as 1:7

In the Ape ....1:4

Macako 1:5

Dog 6 : 11 or 3 : 8

Cat 4 : 11

Rabbit 3 : 8 or 1 : 3

Pig 3:8

Ram 1:3

Stag 2:5

P

2\0 ON THE BRAIN AND NERVOUS SYSTEM.

Roebuck 1:3

Ox 5 : 13

Calf 2:6

Horse 8 : 21

Dolphin . . . . 1 : 13

BIRDS.

Falcon 13 : 34

Owl 14 : 35

Duck 10 : 27

Turkey . . . . . ' . 12 : 33

Sparrow 7 : 18

The following is the passage to which the author refers in his
•* Manual of Natural History." " The e!straordinary strength of the
reproductive power in several amphibia, and the astonishing facility
with which the process is carried on, depend, if I mistake not, on the
great magnitude of their nerves, and the diminutive proportion of
their brain. The former parts are in consequence less dependent on
the latter ; hence the whole machine has less powers of motion, and
displays less sympathy: the mode of existence is more simple, and
approaches more nearly to that of the vegetable world than in the
warm-blooded classes ; but, oh the contrary, the parts possess a
greater individual independent vitality. Since, in consequence of
this latter endowment, stimuli, which operate on one part, or one
system, do not innmediately affect the whole frame by sympathy, as
in warm-blooded animals, we are enabled to explain the peculiar
tenacity of life, which is displayed under various circumstances in
this class; viz. frogs still continue to jump about after their heart
has been torn out ; and turtles have lived for months after the
removal of the whole brain from the cranium. The long continued
power of motion in parts which have been cut off from the body, as
in the tail of the water-newt and blind-worm, may be explained upon
the same principles." § 98.

MAMMALIA.

§ 206. The two large processes of the dura mater, which
form the falx and tentorium, possess a very peculiar structure
in some animals of this class. A strong plate of bone, which
is a process of the neighbouring bones of the cranium, is con-
tained between their two laminae.

We have hitherto ascertained only one example of such a
formation of the falx, in the quadrupeds of this class ; and this
I discovered in the ornithorhynchus, (Plate I. c^) an animal

ON THE BRAIN AND NERVOUS SYSTEM. 211

M-hich abounds in instances of anomalous structure. Some-
thing similar is found in the cetacea, at least in the porpoise,
A similar structure, constituting an unique specimen of anato-
mical variety, is exhibited in the skull of a female, belonging
to my collection. The vitreous table of the frontal bone has a
long falciform bony crista, at the attachment of the falx. The
falx itself descends to various depths between the hemispheres
in the different species.*

A bony tentorium cerebelli is found in a great number of
mammalia ; but its size and extent vary in the different spe-
cies. It is formed by peculiar osseous plates, extending from
the vitreous table of the parietal bones, and the petrous por-
tions of the ossa temporum. Its formation exhibits two kinds
of variety.

In some animals, for instance, it constitutes an uniform bony
partition, which leaves a quadrangular opening into the lower
part of the cranium. This is the case in most species of the;
cat and bear kind ; in the martin, {mustela martes) in the
coaita, {cercopithecus paniscus)\ and others.

It consists of three separate portions in other animals ; one
of these pieces projects from the upper and back part of the
cranium, like a tile; the two lateral portions arise from the
petrous part of the temporal bone. This structure is exem-
plified in the seal, dog, horse, the orycteropus capensis, and
didelphis wombat.

In the cranium of a young seal which I possess, the ante-
rior or upper surface of the tile-shaped piece is connected by
means of a strong perpendicular bony plate, extending to the
middle of the lambdoid suture, with the inner surface of the
occipital bone, where the falx terminates.

In some cases, as in the pig, the rabbit, some mice, &c., a
rudiment of the last mentioned lateral portions may be ob-
served ; or at least the ridge of the petrous portion of the
temporal bone is much larger than usual. I have, in another

* See on this subject Sommering-, Vom Hirn und Buclienmark, Mentz, 1788,
t Josephi's Anatomie der Saügethiere Beytr. zvm 1 iten b. s, 34,^tab. 4.

p 2

21^ ON THE BRAIN AND NERVOUS SYSTEM.

place, described the chief varieties of the bony tentorium,
and have mentioned the uses possibly assigned to this struc-
ture.*

*' It is difficult (says the author, in his Manual of Osteology) to
give a physiological explanation of the use of this bony tentorium.
The opinion which has been generally adopted by anatomists, that
the structure in question belongs to such animals only as jump far,
or run with great velocity, and that it serves the purpose of protect-
ing the cerebellum from the pressure of the cerebrum in these quick
motions, is obviously unsatisfactory. It exists in the bear, which is
not distinguished for its activity, while several animals, which excel
in jumping or springing, do not possess it ; viz. the wild goat,
{capra ibex) in which I could not discover the least trace of such a
structure. Cheselden ascribes it to predacious animals only, {Anat.
of the Bones, cap. 8) but I have already enumerated several others.
It may perhaps obviate the concussion which would arise from
strong exertions in biting ; for such exertions are made' in all the
animals which possess this structure, even by the horse in his wild
state." p. 118.

I have quoted these remarks on the generally assigned use of the
bony tentorium, because a similar mechanical explanation has been
given of the falx and tentorium of the human subject ; viz. that the
former protects the hemispheres from mutual pressure when the per-
son lies with his head resting on one side ; and that the latter pro-
vides against the compression of the cerebellum by the superincum-
bent cerebrum. These explanations are assigned in the present day
by anatomists of such distinguished reputation as Summering and
Cuvier (De Corporis Humani Fabrica, vol. iv. p. 27. Legons d'Anat.
compar. tom. ii. p. 178). If the futility of this piece of physiology
were not sufficiently proved by considering that the cranium is accu-
rately filled, and that there is consequently no room for its contents
to fall from one side to the other, it must immediately be rendered
manifest by Mr. Carlisle's case ; in which the falx was entirely ab-
sent, and the two hemispheres united throughout in one mass, with-
out any perceptible inconvenience during the patient's life. (Transac-
tions of a Society for the Improvement of Medical and Chirurgical
Knowledge, vol. ii. p. 212.) In four instances the anterior half of
the falx has been found deficient. This production of the dura
mater commenced in a narrow form about the middle of the sagittal
suture ; and, gradually expanding, had acquired the usual breadth at
its termination in the tentorium. The two hemispheres adhered by
the pia mater covering their opposed plane surfaces ; but were form-
ed naturally in other respects. A want of the falx has also been re-'
corded by Garengeot {Splanchnologie, tom. ii. p. 24).

* See the Osteologische Handbuch, s. 117, aad the ImtitiUiones Physiologice, p.
174.

ON THE BRAIN AND NERVOUS SYSTEM. 213

§ 207. The peculiarities which distinguish the brain of the
human subject from that of the mammalia,* consist chiefly in
the circumstance, which has been already noticed, of its pos-
sessing a much greater bulk in proportion to the nerves which
arise from it ; and in its being much larger when compared
with the cerebellum and medulla spinalis. t

The anatomy of the brain of cetaceous animals has not been so
minutely described as that of other classes of animals. In general, the
brain of the cetaceous tribe is small compared with the size of the
body. The brain of a common whale, nineteen feet in length, which
was examined by Scoresby, weighed about three pounds and three
quarters, although the weight of the animal was near 11,200 pounds.
Here the weight of the brain was about ^-öW V^^^ ^^ ^^^^ °f ^^^^
body, whilst that of the brain of an adult man is about four pounds,
and that of the body 140, the brain being the -j^ part of the weight of
the whole body. Professor Tiedemann, of Heidelberg, has recently
published an account of the dissection of the brain of the dolphin,
(Treviranus's and Tiedemann's Zeitschrift fur Physiologie, vol. ii. p.
255.) The following are the results of this learned anatomist's investi-
gations.

1. The cerebrum of the dolphin resembles that of the simiae, by its
size, and next to the cerebrum of the orang-outang, most resembles
that of man. Still in proportion to the size of the nerves, spinal
marrow, and cerebellum, it is of much smaller size than the human
cerebrum.

2. Each hemisphere of the cerebrum, as in man and siniicE, consists
of three lobes, an anterior, middle, and posterior. The hemispheres

* The reader may consult the following delineations of the brain of mammalia,
besides those which will be referred to in subsequent notes. Of the chimpanse
(slmia troglodytes) by Tyson, in his excellent Anatomy of a Pigmy, fig. 13, 14. Of
other quadrumana, and of numerous quadrupeds of the different species of mammalia,
Tiedemann, Icones cerebri Simiarum et quorundam Animalium variorum. Heidelb. 1821.
Of the dog, by Collins, System of Anatomy, vol. ii. tab. 53, fig. 1 ; and Ebel, loc,
cit. tab. 1, fig. 7. Of the cat, by Collins, tab. 53,. fig. 2; and Ebel, tab. 1, fig. 3.
Of the horse, by Vicq d'Azyr, Mem. de I'Acad. des Sciences, 1783, tab. 7 ; Ebel,
tab. 1, fig. 1. Of the sheep, by Vicq d'Azyr, tab. 8, fig. 1 ; and Ebel, tab. 1, fig.
8. Of the ox, Vicq d'Azyr, tab. 8, fig. 2; Ebel, tab. 1, fig. 6 and 9. Of the pig.
Collins, tab. 54; Ebel, tab. 1, fig. 10. Of the elephant. Camper, tab. 14. Of
the seal, Vrolek, De phocis, specialim de phoca vitulina, Ultraj. 1822, tab. 1.

t The delineation which I have given of the brain of the mandrill, (papio maimon)
in the two first editions of my work, De Generis Humani Varielate Naiiva, tab. 1,
fig. 1, shews how striking this difference is, even in the quadrumana, which from
their great general resemblance to the human subject have been called Anthropo-
morpha.

214 ON THE BRAIN AND NERVOUS SYSTEM.

are undoubtedly much smaller than those in man, since they do not
completely cover the cerebellum.

3. The breadth of the cerebrum of the dolphin exceeds its length*
which is scarcely the case with any other mammalia.

4. The convolutions of the cerebrum of the dolphin are more nu-
merous than in any other animal, even than in man.

5. The lateral ventricles consist in the dolphin, as in 7nan and simice,
of three horns, whilst in other mammalia the anterior and middle
cornua only exist.

6. The corpora albicantia, in the cerebrum of the dolphin, as of
most mammalia, are united into one mass. In man and the orange
outang they are perfectly distinct.

7. The fornix, septum lucidum, cornua ammonis, and corpora
striata, are in proportion to the size of the cerebrum of the dolphin^
and smaller than the same parts in man.

8. The corpora quadrigemina in the dolphin, as in other mammalia,
are much larger than these bodies in man.

9. The cerebellum of the dolphin is distinguished by its being
larger than in man ; and its middle portion, as in seals and several
other animals, is not symmetrical.

10. The medulla oblongata of the dolphin possesses no trapezium.

11. The brain of the dolphin is particularly distinguished from that
of man and all other mammalia, by the absence of the olfactory nerves.
But on the whole the brain of the dolphin is developed in a greater de-
gree than in any other animal, if we except that of the orang-outang.

§ 208. Moreover, that remarkable and enigmatical collec-
tion of sandy matter, which is found in the pineal gland* of
the human brain, almost invariably after the first few years of
existence, has been hitherto observed in very few other mam-
malia, and those among the bisulca.f

§ 209. In the proper quadrupeds (the quadrumana there-
fore being excepted) the anterior lobes of the brain form two
large processes, {processus mamtllares)X from which the olfac-
tory nerves of the first pair proceed. These are of very con-

* Sömmerring De lapillis, vel prope, vet intra Glandulam pinealem sitis, Mentz,
1785, 8vo.

t Sömmerring has found it in the fallow-deer, (cervus dama) see his TJhs. p. 10;
and Malacarne in the goat, Encephabtomia di alcuni Quadrupedi. Mant. 1795, 4,
p. 31.

t See Metzger Specimen Anatomia: comparatce primi parts Nervorum, in his Opiisc,
Anat. and Physiol. Göthing. 1790, Svo. p. 100.

ON THE BEAIN AND NERVOUS SYSTEM. 215

siderable magnitude, particularly in the herbivorous animals.*
They contain a continuation of the lateral ventricle; which
circumstance has formerly given rise to great physiological
errors.f

§ 210, The structure of the corpora quadrigemina and
catidicantia distinguishes the brain of herbivorous from that
of carnivorous quadrupeds. The nates very considerably ex-
ceed the testes in size, in the former class, while these propor-
tions are reversed in the latter instance. The herbivora have
a single large eminentia candicans ; there are two small ones
in the Carnivora. :|:

With the exception of man and the simise, the mammalia cannot be
said to have posterior lobes of the brain. The cerebellum is seen
behind the cerebrum. The consequence of this is, that the digital
cavity, or prolongation of the lateral ventricle into the posterior lobe,
is wanting.

The convolutions of the cerebrum do not exist in the rodentia.
The simicE only have an olfactory nerve, arising, like that of man, in
a distinct chord from the brain. Other mammalia have a large cor-
tical eminence {^processus mamillaris) filling the ethmoidal fossa. As
the cetacea have no organ of smelling, their brain has neither olfactory
nerve, nor mamillary process.

The annexed tables representing the dimensions of the cerebrum,
cerebellum, corpora quadrigemina, medulla oblongata, and medulla
spinalis, calculated to five decimal parts of the French metre, in the
four classes of vertebrated animals, are taken from the celebrated
work of M. Serres sur V Anatomie comparee du Cerieau dans les quatre
Classes des Animaux vertebres.

* This part is represented in the bisulca, and in the hare-kind, in Collins's System
of Anatomy, vol. ii. tab. 51. Ebel,. loc, cit. Willis, Anatome Cerebri, fig. 2.
Monro On the Ne)'vous 'System, tab. 9 and 24.

t These were first refuted by that excellent anatomist, C. V. Schneider, of Witten-
berg. See his classical work De Osse crihriformi, 1635, 12mo.

J Sommerring, Vom Hirn, &c. p. 91.

216

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

THE LOBES OF THE CEREBRUM IN MAMMALIA.

Man

NAMES OF ANIMALS.

Simla rubra (red ape of Senegal) .
S. sylvanus (Barbary ape) ....
S. cynocephalus (dog-faced baboon)
S. sphj/nx (long-tailed baboon) . .
S. maimon (mandrill) . . . . .

S. apella (sajou)

Lemur macaco (maki vari) .

Ursus arc tos (brown bear) . . .

U. yimencawMs (American black bear)

U. lotor (racoon)

U. meles (badger)

Viverra narica (brown civet)

Mustelafoina (martin) . . . .

M. lutra (otter)

Canis familiaris (domestic dog) . .

C. lupus (young wolf)

C. vulpes (fox)

C. hj/cena (hyaena)

Felis leo (lion) .......

F. tigris (tiger) .......

F. onga (jaguar)

F. pardus (panther)

F. discolor (couguar, or American 7
lion) I

F. lynx (lynx)

Phoca vitulina (common seal) .

Didelphis Virginiana (opossum) .

MEASUHES

Of the Lobes of the Cerebrum.

Antero-

Transverse

Vertical

posterior
diameter.

diameter.

diameter.

Metre.*

Metre.

Metre.

0,17000

0,07500

0,09000

0,07700

0,03300

0,05600

0,07200

0,02950

0,04300

0,07000

0,02825

0,04500

0,08200

0,03400

0,05700

0,08100

0,03200

0,04900

0,05900

0,04300

0,04500

0,02125

0,02900

0,09300

0,04300

0,06100

0,08300

0,03650

0,04800

0,05000

0,02150

0,02900

0,05400

0,02400

0,03200

0,04900

0,01850

0,03150

0,03900

0,01700

0,02400

0,05200

0,02400

0,03400

0,06000

0,02950

0,04400

0,05600

0,02550

0,03200

0,03600

0,01750

0,02800

0,06600

0,02950

0,04100

0,09100

0,04050

0,04800

0,09400

0,04250

0,06400

0,08100

0,03250

0,04800

0,07800

0,03400

0,05000

0,07100

0,02950

0,04200

0,06100

0,02750

0,04200

0,10100

0,04900

0,04400

0,02200

0,01050

0,01450

* The French metre is equal to 3 feet li nails, English.

ON THE BRAIN AND NERVOUS SYSTEM.

217

Dimensions of the Lohes of the Cerebrum in Mammalia.

[Continued.]

NAMES OF ANIMALS.

Antero-post,
diameter.

Macropus major (kangaroo)
PZ/asco/oOTj/s (wombat) . . .

Castor ßber (heavet)

31. alpinus (marmot of the Alps) .
Sciurus vulgaris (squirrel) . . .

Cavia ucuti (agouti)

Dasypus sexcinctus (armadillo) . .

Sus tajassu (pecari)

Hyrax capensis (marmot of the")

Cape). j

Camdus dromedarius (dromedary) .
C llacma (lama)

C. capreolus (roebuck) ....

Common sheep

Delphinus delphis (dolphin) . . .

D. plioccPMa (porpoise)

MEASURES

Of the Lobes of the Cerebrum.

Metre.

0,05300
0,04400
0,04200
0,02975
0,02025
0,03500
0,02650
0,06600

0,03300

0,10500
0,08000
0,06200
0,05800
0,09500
0,08600

Transverse
diameter.

Metre.

0,02350
0,02100
0,02400
0,01466
0,01150
0,01550
0,01300
0,02450

0,01250

0,05050
0,03450
0,02600
0,02650
0,05850
0,06650

Vertical
diameter.

Metre.

0,03800
0,02750
0,02700
0,01950
0,01400
0,02200
0,01700
0,03700

0,02100

0,05800
0,04500
0,04300
0,04300
0,08200
0,05000

^18

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

OF

THE CEREBELLUM IN MAMMALIA.

Man

NAMES OF ANIMALS.

Simia rubra (red ape of Senegal) . ,

S. sabcea (callitriche)

S. sylvanus (Barbary ape)

S. cynocephalus (dog-faced baboon)

S. sphynx (long-tailed baboon) . . .

S. niaimon (mandrill)

S. apella (sajou)

Lemur macaco (maki)

Rhinolophiis unihastatus (horse-shoe bat)
Vespertilio murinus (rear mouse) . . .

Talpa Europcea (mole)

Ursus arctos (brown bear)

U. Americanus (American black bear) .
U. lotor (racoon) .......

U. mdes (badger)

Mustelafoina (martin)

M. martes (pine-martin)

M. lutra (otter)

Canis familiar is (domestic dog) . . .

C. lupus (young wolf)

C. hyana (hyaena)

Felis leo (lion)

F. tigris (tiger)

F. onga (jaguar) . .-

F. pardus (panther)

F, discolor (couguar, or American lion)
F, lynx (lynx)

MEASURES

Of the Cerebellum.

Transverse
diameter.

Metre.
0,12000

0,04500
0,03100
0,03900
0,03800
0,04200
0,05166
0,03600
0,03050
0,00900
0,00800
0,01400
0,06200
0,05900
0,03100
0,03800
0,02800
0,02400
0,02300
0,04200
0,03400
0,04000
0,05500
0,05300
0,05400
0,04850
0,04900
0,03900

Antero-post.
diameter.

Metre.
0,06000

0,02433
0,01800
0,02400
0,02000
0,02650
0,02900
0,02400
0,02200
0,00500
0,00400
0,00925
0,03400
0,03500
0,01900
0,02100
0,01450
0,01400
0,01800
0,02525
0,01700
0,02100
0,03200
0,03900
0,03550
0,03200
0,02500
0,02650

ON THE BRAIN AND NERVOUS SYSTEM.

^19

Dimensions of the Cerebellum in Mammalia,

[Continued.]

NAMES OF ANIMALS.

Phoca vitulina (common seal) . . .
Didelphis Virginiana (opossum) . .
Macropus major (kangaroo) . . .

Phascolo7}7.ys (wombat)

Castor fiber (beaver)

Mus typhlus (blind rat) . . . .
M. alpinus (marmot of the Alps)
Hystrix cristata (crested porcupine)

Lepus cuniculus (rabbit)

Cavia acuti (agoviti) . . . . . .

Dasj/pus sexcinctus (armadillo)

Sus tajassu (pecari)

Hyrax capensis (marmot of the Cape)
Camelus dromedarius (dromedary) .
C. llacma (lama) .

C. capreolus (roebuck) ....
Capra hircus (goat) ......

Common sheep

Delphinus delphis (dolphin)

D. phoccena (porpoise)

MEASUEES

Of the Cerebellum.

Transverse
diameter.

Metre.

0,07250
0,02000
0,03800
0,02200
0,03500
0,01300
0,02450
0,03000
0,01600
0,02300
0,02500
0,03500
0,01400
0,07100
0,04900
0,03900
0,04400
0,03000
0,08500
0,07800

Antero-post,
diameter.

Metre.

0,01200
0,02600
0,01800
0,02000
0,00700
0,01200
0,01800
0,00900
0,01700
0,01300
0,02200
0,01400
0,04600
0,03400
0,03200
0,ÜS900
0,02700
0,04500
0,03300

220 ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

THE CORPORA QUADRIGEMINA IN MAMMALIA.

Man,

NAMES OF ANIMALS.

Simia ruhra (red ape of Senegal) . . .
S. sä6<Ea (callitriche) . . • •, • •

S. Faunus (malbrook)

S. sylvanus (Barbary ape)

S. silenus (wanderow)

S. cynocephulus (dog-faced baboon) .
S. sphynx (long-tailed baboon) . . .

S. mainion (mandrill)

S. capucina (sai)

Lemur macaco (maki)

Rhinolophus unihastatus (horse-shoe bat)
Vespertilio murinus (rear mouse) . . .

Talpa Muropcea (mole)

Ursus arctos (brown bear)

U. A7nericanus (American black bear) .

U. lotor (racoon)

U. meles (badger)

Mustelafoina (martin)

M. martes (pine-martin)

M. Intra (otter) ........

Canis familiaris (domestic dog) . .

C. lupus (young wolf)

C. hyana (hyaena)

ViveiTa civetta (civet)

V. gtnetta (genet-cat)

Felis leo (lion)

F. tigris (tiger)

MEASURES

Of the Corp. Quad.

Transverse
diameter.

Metre.
0,01000

0,00625
0,00600
0,00700
0,00650
0,00575
0,00600
0,00625
0,00650
0,00450
0,00550
0,00300
0,00250
0,00333
0,00850
0,00875
0,00625
0,00600
0,00566
0,00550
0,00500
0,00700
0,00700
0,01000
0,00775
0,00650
0,01200
0,01000

Antero-post,
diameter.

Metre.
0,01100

0,00900
0,00750
0,00833
0,00900
0,00800
0,00733
0,01000
0,01000
0,00850
0,00925
0,00300
0,00250
0,00500
0,01200
0,01200
0,00900
0,01000
0,00800
0,00725
0,00800
0,00975
0,00950
0,01275
0,00950
0,00875
0,01700
0,01300

ON THE BRAIN AND NERVOUS SYSTEM.

221

Dimensions of the Corpora Quadrigemina in Mammalia.

[Continued.]

NAMES OF ANIMALS.

F. onca (jaguar)

F. pardus (panther) . .

F. paradalis (ocelot)

F. discolor (couguar, or American lion)

F.jubrda (Indian tiger)

F. lynx (lynx)

F. catus (cat)

Plioca vitulina (common seal) . . . .
Didelpliis Virginiana (opossum) . . . .

Mncropus major (kangaroo)

Phascolojnys (wombat)

Castor fiber (lieaver)

3(1 us typhlus (blind rat)

M. alpinus (marmot of the Alps) . . .
Hystrix cristata (crested porcupine)

Lepiis cwncidus (rabbit)

Cavia aculi (agouti)

C. paca (paca)

C. Cobaya (Guinea-pig)

Dasyjms sexcinctus (armadillo) . . . .

Sus lajassu (pecari)

S. scrop/ia (wild boar)

Hyrax capensis (marmot of the Cape) .

Equus caballus (liorse)

Ca?nelus dromedarius (dromedary) . .

C. Uucma (lama) .

Antilope kevella (kevel)

A. guzella (gazelle)

A. rupicapra (chamois) ^.

Cervus elaphus (stag)

C. davia (fallow deer)

MEASURES

Of the Corp. Quad.

Transverse
diameter.

Metre.

0,00950
0,00950
0,00775
0,01000
0,00850
0,00900
0,00900
0,00950
0,00600
0,00800
0,00700
0,00700
0,00400
0,00550
0,00600
0,00425
0,00550
0,00775
0,00400
0,00550
0,00S50
0,01000
0,00450
0,01950
0,01250
0,01125
0,00950
0,00933
0,00925
0,01400
0,01300

Antero-post.
diameter.

Metre.

0,01200
0,01200
0,01250
0,01200
0,01150
0,01200
0,01200
0,01500
0,00750
0,01400

0,01000
0,00600
0,00900
0,00S75
0,00700
0,00700

0,00750
0,00550
0,01500
0,01500
0,00700
0,03275
0,02125
0,01S00
0,01700
0,01475
0,00750
0,02100
0,01700

ON THE BRAIN AND NERVOUS SYSTEM.

Dimensions of the Corpora Quadrigemina in MammaUa»

fContinued.]

NAMES OF ANIMALS.

C. capreolus (roebuck) . .
Capra hircus (goat) . .. ,
Bos taurus (ox) . . . .
Common sheep . . . ,
Delphinus delphis (dolphin)

measuhes
Of the Corp. Quad.

Transverse
diameter.

Metre.

0,01050
0,00800
0,00900
0,00S00
0,00700

Antero-post.
diameter.

Metre.

0,01500
0,01300
0,01500
0,01400
0,02475

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

THE MEDULLA OBLONGATA IN MAMMALIA.

Man

NAMES OF ANIMALS.

Simia rubra (red ape of Senegal) . . .

S. sylvanus (Barbary ape)

iS. cynocephalus (dog-faced baboon) . .

S. nemestrina (maimon)

S. rhesus (rhesus)

S. sphynx (long-tailed baboon) . . .

S. maimon (mandrill)

S. leucophea (drill) .......

Lemur macaco (maki)

Rhinolophus unihastatus (horse-shoe bat)
Vesperlilio viurinus (rear mouse) .
Erinaceus Europceus (hedgehog) . .

Talpa Europcea (mole)

Ursus arctos (brown bear)

U. Americanus (American black bear) .

U. lotor (racoon)

U. meles (badger)

Viverra narica (brown civet) ....

V. nasjca (red civet)

Mustela foina (martin)

M. Intra (otter)

Canis familiaris (domestic dog) . . .

C lupus (young wolf)

C. vulpes (fox)

C. hycBna (hyaena)

Viverra cafra (civet of the Cape) . . .

Felis leo (lion)

F. tigris (tiger)

P. on<^a (jaguar)

F, pardus (panther)

MEASURES

Of the Medulla
Oblongata

Metre.
0,02000

0,01375
0,01300
0,01150
0,01400
0,01500
0,01400
0,01500
0,01450
0,01266
0,00450
0,00350
0,00700
0,00700
0,02100
0,02100
0,01300
0,01700
0,01400
0,01500
0,01300
0,01300
0,02000
0,01050
0,01300
0,01900
0,01000
0,02400
0,02400
0,02250
0,01450

224!

ON THE BRAIN AND NERVOUS SYSTEM.

Dimensions of the Medulla Oblongata in Mammalia.

[Contiaued.]

NAMES OF ANIMALS.

MEASURES

Of the Medulla
Oblongata.

F. discolor (couguar, or American lion)

F. /j/??r (lynx)

Phoca vitulina (common seal) . .
Didelphis Virginiana (opossum) . .
Macropus major (kangaroo) . .

Vhascolomys (wombat)

Castor fiber (beaver)

Mus nitela (lerot)

M. typhlus (blind rat)

M. alpinus (marmot of the Alps)
Sciurus vulgaris (squirrel) ....

Cavia acuti (agouti)

Dasypiis sexcinctus (armadillo) . . .
Sus tajassu (pecari) . .......

Hyrnx capensis (marmot of the Cape)

Equus cahallus (horse)

£.. asinus (ass)

E. zebra (zebra)

Camelus dromedarius (dromedary)

C llac?na (lama)

Cervus elaphus (stag)

C capreolus (roebuck)

Goat of Upper Egypt

Bos taurus (ox) . . . ...

Common sheep

Delphinus delplds (dolphin) ....
D. phoccena (porpoise)

Metre.

0,02150
0,01600
0,02300
0,01100
0,02200
0,01700
0,01600
0,00450
0,00600
0,01200
0,00900
0,01200
0,01500
0,02100
0,00950
0,03200
0,02500
0,02400
0,03600
0,0-2500
0,01900
0,02100
0,01900
0,03350
0,01600
0,01900
0,01600

ON THE BRAIN AND NERVOUS SYSTEM.

225

DIMENSIONS

THE MEDULLA SPINALIS IN MAMMALIA.

Simia rubra (red ape of Senegal)

S. sr/lvanus (Barbary ape)

S. cynocephalus (dog-faced baboon) .

S. nemestrina (maimon)

S. rhesus (rhesus) .

S. sphynx (baboon)

S. maimon Cmandrill) . . . .

S. leucophea (drill)

S. apella (sajou)

Lemur macaco (maki) ' •

Rhinolophus unihastatus (horse-shoe bat)
Vespertilio niurinus (rear mouse) , . " .
Erinaceus Europtzus (heägehög) .
Talpa EuropcBa (mole) . . .'.'.■.
Ursus arcios (brown bear) ..'.■,'.
U. y4?«ericrtm/s (American black bear) .
U. lolor (racoon) ... .... .

U. mtk'S (badjjer)

Vivena narica (brown civet) ....

V. nasua (red civet) .......

Mustela foina (martin) . . . . .

M. lulra (otter)

Canis faniiliaris (domestic dog)

C. lupus (young wolf)

C. vulpes (fox)

C. ht/cEim (hyaena)

Viverra cufra (civet of the Cape) . . .

Felis leo (lion)

F. ligris (tiger)

F. onqa (jaguar)

Metre.
0,01100

0,00900

0,00S00

0,00900

0,00700

0,00775

0,01000

0,00950

0,00800

0,00550

0,00S00

0,00200

0.00200

0,00400

0,00350

0,01700

0,01300

0,00800

0,00800

0,00800

0,01050

0,00700

0,00750

0,01100

0,00600

0,00900

0,01300

0,00650

0,01700

0,01600

0,01400

226

ON THE BRAIN AND NERVOUS SYSTEM.

X)imensions of the Medulla Spinalis in Mammalia.

[Continued.]

NAMES OF ANIMALS.

F. pardus (panther)

F. discolor (couguar, or American lion)

F. lynx (lynx) . i

Phoca viiidina (common seal) . . .
Macropus major (kangaroo)

Phascolomys (wombat)

Castor fiber (beaver)

Mus nitela (lerot)

M. typhlus (blind rat)

Bl. alpinus (marmot of the Alps)
Sciurus vulgaris (squirrel) ....

Cavia acuti (agouti)

Dasypus sexcinctns (armadillo) . .

Sus tajassu (pecari)

Hyrax Capensis (marmot of the Cape)

Equus cahallus (horse)

F. asinus (ass)

E. zebra (zebra)

Camelus dromedarius (dromedary)

C llacma (lama)

Cervus elaphus (stag)

C. capreolus (roebuck)

Goat of Upper Egypt

Bos taurus (bull) ..;....

Common sheep

Delphinus delphis (dolphin)

MEASURES

Of the Medulla
Spinalis.

Metre.

0,01300
0,01200
0,01 100
0,01150
0,01200
0,00900
0,00800
0,00325
0,00300
0,00450
0,00500
0,00700
0,00900
0,01050
0,00550
0,02000
0,01500
0,01400
0,01900
0,01200
0,00800
0,01300
0,01100
0,01900
0,00900
0,01000
D. phoccena (porpoise) 1 0,00800

ON THE BRAIN AND NERVOUS SYSTEM. 227

BIRDS.

§211. The dura mater forms, in some birds, a falciform
process ; which has been erroneously asserted to be deficient
in the whole class.* In the cock of the woods, {tetrao urogal-
lus) f it has a bony structure resembling that of the ornitho-
rhynchus.

\2\2. The brain itself, considered altogether, resembles that
of the former class (even in forming in some instances a kind
oi processus mamillares); while, on the contrary, it is striking-
ly distinguished from that of the following order. It differs,
however, from that of the mammalia, not only in the smooth-
ness of its surface, and the want of convolutions, but also in
the structure of the optic thalami. These eminences, which
are nearly spherical, and hollow internally, are not contained
in the proper brain or cerebrum, but lie behind and below
that part. This structure is common to birds with the two
classes of cold and red blooded animals. Those eminences
also, which in the mammalia are justly termed corpora striata,
are of an uniform colour in birds.

Cuvier represents the brain of birds to consist of six tubercles, visi-
ble exteriorly ; viz, the two hemispheres, the optic thalami, a cere-
bellum, and medulla oblongata.

* This mistake has even been committed by Haller, De Partium Corp. Hum.
Fabrica et Functionibus, torn. viii. p. 163.

t The brain of this bird is remarkably small in proportion to the size of its head
and whole body ; while we know, that in some other animals of this class, particu-
larly among the singing-birds, the brain exceeds that of the human subject in these
points of view.

Q 2

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

THE LOBES OF THE CEREBRUM IN BIRDS.

NAMES OF BIRDS,

Vulturfulvus (vulture)

Falco fulvus (common eagle) . .
F. ossifragus (sea eagle) . . . .
F, CErvginosus (buzzard) . . . .

F. buteo (hawk)

F. communis (falcon) , . . . .
Slrix bubo (great horned owl) .
Motacilla regulus (gold-crowned ")

wren) 5

Hiriindo rustica (swallow) . . .
Alauda arvensis (lark) . . . . .
Fringilla domestica (sparrow)

F. ccelebs (chaffinch)

F. linaria (linnet)

F. canaria (canary-bird) . . . .

Corvus pica (magpie)

African parrot

Meleagris gallopavo (turkey) . .
Phasianus gallus (common fowl)
P. nycthemerus (silver pheasant) . .
Struthio cainelus (ostrich) , . . .
S. casuarius (cassowary) . .

Otis tarda (bustard)

Ardea ciconia (white stork) . . .
A. pavonina (royal crane) . . .

Goeland

Pelecanus Bassanus (solan goose) ,

Anas anser (goose)

A. bernicla (barnacle goose) .

A. moschata (musk duck) . . .

A. mollissima (eider duck) . . .

MEASURES

Of the Lobes of the Cerebrum.

Antero-post,
diameter.

Metre.

0,03200
0,03200
0,02800
0,01200
0,01700
0,01900
0,02500

0,09000

0,01000
0,01100
0,01100
0,01200
0,01150
0,01200
0,02000
0,02900
0,01750
0,01800
0,01475
0,01550
0,03800
0,04500
0,03200
0,02400
0,02000
0,01300
0,02500
0,02700
0,02460
0,02200

Transverse
diameter.

Metre.

0,02200
0,02400
0,01900
0,01400
3,01500
0,01450
0,01800

0,00600

0,00600
0,00700
0,00650
0,00700
0,00650
0,00600
0,01400
0,01400
0,01250
0,01200
0,01233
0,01200
0,02200
0,02350
0,01450
0,01600
0,01350
0,02000
0,01300
0,02500
0,02700
0,02450

Vertical
diameter.

Metre. .

0,01550
0,02100
0,02100
0,01200
0,01350
0,01200
0,02000,

0,00550;

0,00600

0,00650

0,00700

0,00700

0,00600

0,00700

0,01200

0,01700'

0,01200

0,01200

0,01100

0,01200:

0,02400

0,02000

0,01400

0,01900

0,01300

0,02100

0,01400

0,01700

0,01150

0,01700

ON THE BRAIN AND NERVOUS SYSTEM.

229

DIMENSIONS

OF

THE CEREBELLUM IN BIRDS.

NAMES OF BIRDS.

F. ossifragus (sea eagle) .* . . .
F. (Bruginosus (buzzard) . . . . ,

F. buieo (hawk)

Strix ulula (owl)

Motacilla regulus (gold-crowned wren)
Hirundo urbica (swallow) . ." . .
Alauda arvensis (lark) .....

Fringilla doniestica (sparrow) .

F. coslebs (chafBnch) .....

F. linaria (linnet) . . . ...

F. canaria (canary bird) . '. '. .
F. cardudis (goldfinch) . i . .
Loxia chloris (greenfinch)
Corvus pica (magpie) .....

C. corax (crow) .......

Amazonian parrot .....

African parrot .......

Turtle-dove .

Meleagris gallopavo (turkey) . . .
Phasiunus gallus (common fowl) .
P. nr/cthemerus (silver pheasant) .
P. pictus (golden pheasant) . . . ,
Tetrao cintreus (partridge) . . . .
Struihio caniclus (ostrich) ....

S. casuarius (cassowary)

Otis tarda (bustard)

Ardca pavonina (royal crane) . . .

Goeland

Anas mollimma {(nAer Anck) ...

MEASURES

Of the Cerebellum.

Transverse
diameter.

Metre.

0,01050
0,01400
0,01500
0,01125
0,00300
0,00500
0,00700
0,00500
0,00600
0,00650
0,00500
0,00500
0,00600
0,01100
0,01100
0,01700
0,01300
0,00900
0,01350
0,00900
0,01100
0,01200
0,01075
0,01750
0,01900
0,00975
0,01050
0,01200
0,01000

Antero-post.
diameter.

Metre.

0,02033
0,01250
0,01600
0,01400
0,00400
0,00600
0,00500
0,00525
0,00400
0,00500
0,00525
0,00400
0,00575
0,01150
0,01300
0,01300
0,01200
0,01000
0,01600
0,01100
0,01025
0,01100
0,00950
0,02500
0,02200
0,01800
0,01800
0,01700
0,01bOO

g30

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

THE CORPORA QUADRIGEMINA IN BIRDS.

NAMES OF ANIMALS.

Vitltusfulvus (vulture)

Falco chrysaetos (golden eagle) .

F. ossifragus (sea eagle) . . . . .

F. coinmunis (falcon)

F. CBruginosus (buzzard) . . . . ,

F. huteo (hawk)

Motucilla regubis (gold-crowned wren)

Hirimdo urbica (swallow)

Alauda arvensis (lark)

Fringilla domesdca (sparrow) . .

F. caelebs (chaffinch)

F. linaria (linnet)

F. canaria (canary bird)

F. carduelis (goldfinch)

Loxia cldoris (greenfinch)

C. pica (magpie)

Amazonian parrot

Afi-ican parrot

Mdeagris gallopavo (turkey) . . . .
Phasianus gallus (common fowl) . .
P. nyctlieinerus (silver pheasant) . .
P. picius (golden pheasant) . . . .

Strutlno camelus (ostrich)

iS. casuarius (cassowary)

Otis tarda (bustard)

Ardea ciconia (white stork) . . . .

A. pavonina (royal crane)

Goeland

MEASURES

Of the Corp. Quad.

Transverse
diameter.

Metre.

0,00S00
0,00800
0,01 100
0,00725
0,00550
0,00600
0,00300
0,00475
0,00425
0,00400
0,00400
0,00300
0,00325
0,00325
0,00400
0,00600
0,00625
0,00600
0,00725
0,00800
0,00850
0,00700
0,01125
0,01000
0,00800
0,00800
0,00900
0,00800

Antero-post.
diameter.

Metre.

0,01200
0,01200
0,01100
0,00775
0,00900
0,00900
0,00250
0,00450
0,00400
0.00350
0,00400
0,00300
0,00300
0,00300
0,00350
0,00600
0,01000
0,00700
0,00875
0,00900
0,00900
0,00800
0,01100
0,01050
0,00775
0,01200
0,00900
0,00800

ON THE BRAIN AND NERVOUS SYSTEM,

^31

Dimensions of the Corpora Quadrigemina in Birds.

[Continued.]

NAMES OF BIRDS.

MEASURES

Of the Corp. Quad.

Transverse
diameter.

Antero-post.
diameter.

Pelecanus Bassanus (solan goose) ....

Anas anser (goose)

A. bernicla (barnacle goose)

A. moscliata (musk duck)

A. moUissima (eider duck)

Metre.

0,00900
0,00700
0,00650
0,00300
0,00600

Metre.

0,01100
0,00850
0,00900
0,00975
0,00625

232

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

OF

THE MEDULLA OBLONGATA IN BIRDS.

NAMES OF BIRDS.

MEASURES

Of the Medulla
Oblongata

Vultusfuhus (vulture)

Falco chrysnetos (royal eagle) . . . .
F. ossifragus (sea eagle) . . . . .
F. communis (falcon) ......

F. ceruginosus (buzzard)

F. buteo (hawk)

Strix bubo (great horned owl) . . ,
Motacilla regulus (gold-crowned wren) .

Hirundo urbica (swallow)

Alauda arvensis (lark)

Fringilla domestica (sparrow) e . . .

F. coslebs (chaffinch)

F. linaria (linnet)

F. canaria (canary bird)

F. carduelis (goldfinch)

Loxia chloris (greenfinch) . . .

C. pica (magpie)

Amazonian parrot

African parrot

Meleagris gallopavo (turkey) . . . ,
Phasianus gallus F. (common fowl, hen)
P/iasinnus gullus M. (cock) . . .

Capon

P. nj/ct/iemerus (silver pheasant) .
P. pictus (golden pheasant) ...
Columha palumbus (pigeon)
Tretrao ciiiereus (grey partridge) . .

Struthio camelus (ostrich)

S. casuurius (cassowary)

Otis tarda (bustard) ,

Ardea ciconia (white stork) . . . .

A. nigra (black stork)

A. pavonina (royal cra;ne) ....

Metre.

0,01100
0,01400
0,01700
0,00800
0,00900
0,00900
0,00900
0,00300
0.00350
0,00400
0,00375
0.00450
0,00375
0,00300
0,00300
0,00400
0,00800
0,01000
0,00900
0,00950
0,01000
0,01100
0,00800
0,01025
0,00950
0,00600
0,00550
0,01600
0,01600
0,01000
0,01533
0,01400
0,00900

ON THE BRAIN AND NERVOUS SYSTEM,

233

Dimensions of the Medulla Oblongata in Birds.

[Continued.]

NAMES OF BIRDS.

Goeland

Pelecanvs Bassanus (solan goose)
Anas nnser (goose) ....
4. ^ernz'c/a (barnacle goose)
A. moschata (musk duck) . - .
A. bosclms (common duck)
A. mollissima (eider duck) .

MEASURES

Of the Medulla
Oblongata,

Metre.

0,01000
0,01400
0,01050
0,01 100
0,01400
0,01400
0,01100

234/ ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

OF

THE MEDULLA SPINALIS IN BIRDS.

NAMES OF BIRDS.

MEASUHES

Of the Medulla
Spinalis.

Vultusfulvus (vulture)

Falco chrysaetos (royal eagle) . . . .

F. ossifragus (sea eagle)

F. communis (falcon)

F. (ETVginosus (buzzard)

F. buteo (hawk)

Strix bubo (great horned owl) . . . .
Motacilla regulus (gold-crowned wren) .

Hirundo urbica (swallow)

Alauda arvensis (lark)

Fringilla domestica (sparrow) . . . .

F. coelebs (chaffinch)

F. linaria (linnet)

F. canaria (canary bird) . . ...

F. carduelis (goldfinch)

Loxia chloris (greenfinch)

C. pica (magpie)

Amazonian parrot

African parrot

Bfeleagris gallopavo (turkey) . . . .
Phasianus gallus F. (common fowl, hen)
Pkasianus gulliis M. (cock) . . . .
P. nycthemerus (silver pheasant) .
P. pictus (golden pheasant) . . . .

Columba palumbus (pigeon)

Tetrao cinereus (grey partridge) .

Struthio cajndus (ostrich)

S, casuarius (cassowary)

Otis tarda (bustard)

Ardea ciconia (white stork) . . . .

A. nigra (black stork)

A. pavonina (royal bird)

Goeland

Metre.

0,00800
0,00800
0,00600
0,00500
0,00550
0,00400
0,00600
0,00125
0,00175
0,00225
0,00175
0,00233
0,00150
0,00150
0,00200
0,00200
0,00450
0,00400
0,00400
0,00500
0,00425
0,00475
0,00550
0,00500
0,00400
0,00300
0,00700
0,00800
0,00600
0,00750
0,00700
0,00500
0,00500

ON THE BRAIN AND NERVOUS SYSTEM.

235

Dimensions of the Medulla Spinalis in Birds.

[Continued.]

NAMES OF BIRDS.

MEASURES

Of the Medulla
Spinalis.

Pelecavus hassanus (solan goose)
Anas anser (goose) ....
A. bernida (barnacle goose) .
A. moschata (musk duck) .
A, boschus (common duck)
A. mollissima (eider duck) .

Metre.

0,00750
0,00600
0,00600
0,00700
0,00675
0,00600

236 ON THE BRAIN AND NERVOUS SYSTEM.

§ 21S. The brain of birds does not possess several parts,
which are found in that of the mammaha, and the opinions of
anatomists are much divided concerning others, on account of
variations in their structure and appearance. The corpus
callosum, pons varolii, &c. come under the description of
parts, which are certainly absent. The existence of the for-
nix, pineal gland, corpora candicantia and quadrigemina, is a
matter of dispute.*

AMPHIBIA.

§ 214. Anatomists have hitherto bestowed but little labour,
comparatively speaking, on the brain of amphibia. It is small
and simple, and consists of five roundish eminences ; viz. the
two hemispheres, the two thalami nervorum opticorum, lying
behind these, and separate from them, and excavated by a
ventricle ; and the cerebellum, which in both classes of cold
red-blooded animals contains no arbor vitae. The spinal mar-
row, compared with the brain, is of astonishing magnitude in
most amphibia.*!*

The dura matter forms no processes in the amphibia, nor in the
fishes.

* See Haller's valuable observations, de cerebro avium, in the Ojpera Minm-a, vol.
iii. ; and Malacarne's long commentary on them in the three first volumes of the
Memorie della Societaltaliana,

Several authors have given representations of the brain of birds. That of the
goshawk, Üie owl, the finches, (fringilla) the pigeon, the partridge, and the goose,,
has been delineated by Ebel, loc. citat.

That of the kingfisher, the red bird, (loxia cardinalis') the turkey, the bustard,
the woodcock, snipe, and others of the genus scobpax, the swan, goose, and duck,
by Collins, loc. citat. tab. 49, 56, 57, and 58.

That of the raven and common cock by Vicq d'Azyr, in the M^moires de I'Acad.
des Sciences, 1783, tab. 9 and 10.

That of the goose in a lateral and internal view, by Ludwig, De Cinei'ea Cerebri
Substantia. Lips. 1779, 4to. fig. 1.

t The brain of the tortoise has been delineated by Caldesi, in his Observations,
&c. tab. 2, fig. 5. That of the frog by Ludwig, Vicq d'Azyr, and Ebel, locis citatis ;
and that of the viper by Vicq d'Azyi', tab. 10, fig. 8.

ON THE BRAIN AND NERVOUS SYSTEM. 2S7

DIMENSIONS

OF THE

LOBES OF THE CEREBRUM IN REPTILES.

NAMES OF ANIMALS.

MEASURES

Of the Lobes of the Ce-
rebrum.

Antero-post,
diameter.

Testudo grcEca (tortoise) . . . . .

T. mydus (green turtle)

Crocodilus Niloticvs, (common crocodile^

Adult crocodile

C. sclerops (alligator)

C. lucius (pike-headed alligator)

L. agilis (grey lizard)

Lacerta viridis (green lizard) ....

Tupinambis .........

L. Africana (common chameleon^ . .
Anguis fragilis (blind-worm) ....

Amphisbaena

Coluber beras (adderj ......

Ringed snake

C. haje (haje viper)

Rana esculenta (common frog) .

Metre.

0,01600
0,01900
0,00800
0,01800
0,00700
0,03100
0,00500
0,00350
0,00400
0,00600
0,00250
0,00500
0,00400
0,00550
0,00575
0,00500

Transverse
diameter.

Metre.

0,00500
0,01000
0,00500
0,01500
0,00400
0,01100
0,00275
0,00250
0,00300
0,00333
0,00200
0,00300
0,00300
0,00400
0,00400
0,00400

238

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

THE CEREBELLUM IN REPTILES.

NAMES OF ANIMALS.

Testudo groeca (tortoise)

T. mydas (green turtle) . . . . .
Grocodilus Niloticus (common crocodile)

C. sclerops (alligator)

C. lucius (pike-headed alligator) . . •

L. agilis (grey lizard)

Lacerta viridis (green lizard) . . . .

Tupinambis . .

L. Africana (common chameleon) . .
Anguis fragilis (blind- worm) . . . .

Coluber beras (adder)

Ringed snake

C. haje (haj6 viper)

Rana escuknta (common frog) . . .

MEASURES

Of the Cerebellum.

Transverse
diameter.

Metre.

0,00400
0,01125
0,00500
0,00400
0,01400
0,00150
0,00175
0,00.S50
0,00375
0,00100
0,00200
0,00175
0,00175
0,00300

Antero-post.
diameter.

Metre.

0,00300
0,01100
0,00400
0,00300
0,01000
0,00150
0,00150
0,00500
0,00175
0,00100
0,00233
0,00200
0,00200
0,00200

ON THE BRAIN AND NERVOUS SYSTEM.

239

DIMENSIONS

CORPORA QUADRIGEMINA IN REPTILES.

NAMES OF ANIMALS.

Testudo graca (tortoise)

T. 7nydas (green turtle)

Crocodilus Niloticus (common crocodile)

C. sclerops (alligator)

Lacerta viridis (green lizard)

L. agilis (grey lizard)

Tupinambis

L. Africana (common chameleon) . .
Anguisfragilis (blind-worm) ....
Coluber natrix (ringed snake) . . .

Coluber beras (adder)

Ringed viper

C. haje (baje viper)

Ranae sculenta (common frog) . . .

MEASURES

Of the Corp. Quad.

Transverse
diameter.

Antero-post.
diameter.

Metre.

0,00200
0,00700
0,00S00
0,00225
0,00150
0,00175
0,00250
0,00300
0,00100
0,00200
0,00200
0,00225
0,00200
0,00300

Metre.

0,00350
0,00650
0,00350
0,00275
0,00150
0,00150
0,00300
0,00250
0,00100
0,00300
0,00300
0,00300
0,00200
0,00400

^40

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

THE MEDULLA OBLONGATA IN REPTILES.

NAMES OF ANIMALS.

Testudo grceca (tortoise)

T. mydas (green turtle)

Crocodilus Niloticus (common crocodile)

C. sclerops (alligator)

Lacerta viridis (green lizard) . . . .

L. agilis (grey lizard)

Tupinambis

L. Africana (conamon chameleon) . .
Anguis fr agilis (blind- worm) . . . .
Crotalus horridus (rattle -snake) . . .

Coluber beras (adder)

Ringed viper

C. haje (haje viper)

Rana esculenta (common frog) . . .

MEASURES

Of the Medulla
Oblongata.

Metre,

0,00500
0,01050
0,00500
0,00425
0,00250
0,00200
0,00333
0,00400
0,00225
0,00700
0,00325
0,00350
0,00300
0,00400

ON THE BRAIN AND NERVOUS SYSTEM.

241

DIMENSIONS

THE MEDULLA SPINALIS IN REPTILES.

NAMES OF ANIMALS.

MEASURES

Of the Medulla
Spinalis.

TeStudo gmca (tortoise)

T. radiata (striped turtle)

T. my das (green turtle)

Crocodilus Niloticus (common crocodile)

C. sclerops (alligator)

Lacerta viridis (green lizard) . . . .

L. agilis (grey lizard)

Tupinambis

L. Africana (common chameleon)
Anguis fr agilis (blind worm) . . . .
Coluber natrix (ringed snake) . . . .
Cr o talus horridus (rattle- snake) .

Coluber beras (adder)

Ringed viper .

C. haje (haje viper)

Bxma escuknta (common frog) . . .

Metre,

0,00300
0,00500
0,00500
0,00300
0,00250
0,00175
0,00166
0,00200
0,00225
0,00133
0,00125
0,00400
0,00200
0,00150
0,00175
0,00300

Ü4>2 ON THE BRAIN AND NERVOUS SYSTEM.

FISHES.

§ 215. In this class of animals the brain does not fill the
cranium. Between the pia and dura mater (which in most of
the large fishes approaches to a cartilaginous firmness) there
is collected a salt and greasy fluid, contained in a loose cellu-
lar texture, which seems to supply the place of the tunica
arachnoidea.*

§ 216. The structure of the brain varies in the different
genera and species ; sometimes even in the individuals of the
same species. It consists of several tubercles or lobuli disposed
in pairs ; and of these, the five, which were described in the
brain of the amphibia, are the most constant.-f

§ 217. In most fishes the optic nerves decussate (just like
two fingers laid crosswise), a remarkable peculiarity, which
has given rise to several physiological investigations and infer-
ences.J

Tn the skate, the right nerve goes through a fissure in the left ; in
bony fishes the decussation is more manifest, as one nerve merely lies
on the other without any intermixture of substance. The fact has
been noticed by Collins, Willis, and several others ; it is represented
by Ebel in the pike, carp, and silurus glanis (Obs. Neurol, ex Anat.

* Casserius has given an excellent view of the cranium of a pike laid open, Be
Auditu, tab. 12.

t Haller, De Cerabro Piscium, in the Opera Minora, torn. iii. p. 198. Collins
has given representations of the brain in almost all the orders of fishes ; but his
views are chiefly of the upper external surface, tab. 60 to 70. That of the skate is
delineated in the 2nd vol. of Camper's smaller- writings, tab. 3 ; by Monro, in his
Physiology of Fishes, tab. 1, 34, and 37 ; and by Scarpa, De Auditu et Ölfactu,
tab-. 1, fig. 1. That of the shark, by Stenonis, Elementa Myolog. tab. 5 and 7, and
by Scarpa, loc. citat. tab. 2. That of the frog-fish, (lophius piscatorius) by Camper,
loc, citat. tab. I.

That of the congor-eel, turbot, and pike, by Vicq d'Azyr, loc. citat. tab. 10. That
of the cod, by Camper, loc^ citat. and Monro. That of the haddock, by Monro, On
the Nervous System, tab. 32. That of the silurus, by Ebel, loc. cit. tab. 2, fig. 4.
That of the pike by Casserius, Ebel, and Scarpa, locis citatis. That of the carp by
Ebel and Scarpa.

if See Sömmering, in the Hessischen Bey träge zur Gelehrsamkeit, vol. i. pt. 2, p. 205 ;
also his Dissert, de Decussatione Nervor. Opticw. Mogunt. 1786, p. 24. Coopman's
Neurolog. p. 38. Professor Rudolphi, in Wiedemann's Archives, vol. i. part ii. p.
156, and several of the delineations quoted in the preceding note.

ON THE BRAIN AND NERVOUS SYSTEM. 243

comp. tab. 2, fig. 2, 3, and 4 ; this dissertation is contained in the 3rd
Vol. of Ludvvig's Scriptores Neurol. Minores). It does not seem to
have been much investigated in birds and the amphibia. In eight
instances, where the eye of an animal had been destroyed or injured,
the optic nerve was found to be altered in structure and appearance
as far as the union ; and beyond that point the alteration extended
along the opposite nerve to the opposite thalamus. (See Ebel, lac.
cit. tab. 1, fig. 1 and 2.) A similar appearance has been found in a
man. Sommering De Decussat. Nerv. Optic, in Lud wig's Collection,
torn. i.

These nerves have in some fishes the uncommon structure
of an investment of pia mater, containing very elegant longitu-
dinal folds.*

The olfactory nerve sometimes forms a ganglion just before
it is distributed to the nose. The gadus merluccius and the
carpi afford examples of this structure, which is remarkable,
inasmuch as no ganglia have been hitherto observed in the
nervous system of fishes. .

§ 218. We must lastly mention those nerves which are dis-
tributed in the electrical fishes, to that wonderful apparatus of
membranous cells, filled with a gelatinous substance like white
of egg, and performing the office of a Leyden jar, or electrical
battery. These curious organs occupy the lateral fins of the
torpedo,:|: and receive their nervous supply from the fifth pair.
In the electrical eel, {gymnotus) the electrical organ is found
towards the posterior part of the abdomen,§ and its nerves
come from the medulla spinalis. In the silitrus electricus it is
placed between the skin and muscles over the whole body,
and its nerves are derived from the eighth pair.||

• See Eustachii, Ossium Examen, p. 227, and a representation from the saw-fish,
{squalus prislis) in Malpighi, De Cerebro. In order to compare this with the ordi-
nary structure of other nerves, see the representation of the physiological prepara-
tion of the commencement of the fifth pair in the elephant, in A. K. Boerhaave His-
toria anatomica infaniis, cvjus pars Corporis inferior monstrosa. Petersburg, 1754,
4to. tab. 1.

t Scarpa, loco ciialo.

X Hunter, in the Philoi. Trans, vol. Ixiii. p. 481, tab. 20; and Girardi, in the
Memorie delta Societa Italiana, tbm. iii. p. 553.

$ Hunter, in the Philus. Tram. vol. Ixv, p. 395, tab. 9.

II Geoffroy, in the Bulletin de la Soci^te Philtrmatiqne, 6 ann^e, tom. iii. p. 169.

II 2

£44

ON THE BRAIN AND NERVOUS SYSTEM«

DIMENSIONS

OF

THE CEREBRUM IN FISHES.

NAMES OF FISHES.

Petromyzonfluvialis (lesser lamprey)
Squalus carcharias (white shark)

S. acanthius (aguilat)

S. griseus (grey shark)

S. glaucus (blue shark) . . . .

Raya clavata (ray)

R. rubua (red ray)

Acipenser sturio (sturgeon)

Esox lucius (pike)

Cyprinus carpio (carp)

C. tinea (tench)

Gadns inorrhua (cod)

G. eglefinus (haddock)

G. merlangus (whiting) . . . ,

Pleuroncctes maximus (turbot)

Murcena anguilla (eel) ....

M. conger (congor eel)

Trigla lyra (flying-fish) . . .

Lophius piscatorius (frog-fish)

MEASURES

Of the Cerebrum.

Antero-post,
diameter.

Metre.

0,00400
0,02300
0,01100
0,03000
0,01700
0,01500
0,01650
0,00600
0,00700
0,00600
0,00400
0,00725
0,00100
0,00500
0,00600
0,00400
0,00750
0,00600
0,00400

Transverse
diameter.

Metre.

0,00300
0,01100
0,01000
0,01600
0,00700
0,01300
0,01300
0,00550
0,00550
0,00500
0,00300
0,00800
0,00100
0,00400
0,00450
0,00300
0,00600
0,00500
0,00300

ON THE BRAIN AND NERVOUS SYSTEM.

24.'

DIMENSIONS

THE CEREBELLUM IN FISHES.

NAMES OF FISHES.

MEASURES

Of the Cerebellum.

Transverse
diameter.

Antero-post.
diameter.

Petromyzon ßuvialis (lesser lamprey)

Squalus carcharias (white shark)

S. acanthias (aguilat)

S. griseus (grey shark)

S. glaucus (blue shark) ....

Raya cluvata (ray)

R. rubus (red ray)

Acipenser sturio (sturgeon) . .

Esox lucius (pike) ......

Cyprinus carpio (carp)

C tinea (tench)

Gadus morrhua (cod)

G. eglefinus (haddock)

G. merlangus (whiting) ....

Pleuronectes maximus (turbot)

j Murcznu anguilla (eel)

I M. conger (congor eel) ....

Trigla lyra (flying-fish) ....

Lnphius piscatorius (frog-fish) . .

Metre.

0,00225
0,01700
0,01500
0,02700
0,01075
0,03400
0,02000
0,01300
0,00600
0,00675
0,00500
0,01350
0,00800
0,00600
0,00750
0,00600
0,01075
0,00900
0,00700

Metre.

0,00100
0,03100
0,01700
0,02200
0,02100
0,02500
0,03500
0,01600
0,00633
0,00800
0.00550
0,01700
0,01000
0,00625
0,00900
0,00450
0,00900
0,00633
0,00400

246

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

ow

THE CORPORA QUADRIGEMINA IN FISHES.

NAMES OF FISHES.

Fetromi/zonßuvialis (lesser lamprey)
Squalus carcharias (white shark) .

S. acanthias (aguilat)

5. griseus (grey shark)

S. glaucus (blue shark) . . . .
üflj/a clavata (ray) ......

R. rubus (red ray)

Acipenser sturio (sturgeon)

Esox lucius (pike)

Cj/prinus carpio (carp) . . . . ,

C tinea (tench)

Gadus morrhua (cod) . . . . ,
G. egleßnus (haddock) . . . . .
G, merlangus (whiting) . . . . ,
Pleuronectes maxwms (turbot) .
Murcena anguilla (eel) . . . . ,
M. conger (congor eel) . . . .
Trigla lyra (flying-fish) ... ,
Lophius piscatorius (frog-fish)

MEASURES

Of the Lobes of the
Cerebellum.

Transverse
diameter.

Metre.

0,00200
0,00700
0,00600
0,01100
0,00633
0,00900
0,00800
0,00350
0,00575
0,00700
0,00400
3,00800
0,00600
0,00433
0,00433
0,00350
0,00600
0,00800
0,00500

Antero-post,
diameter.

Metre.

0,00233
0,01800
0,01075
0,01700
0,01250
0,01500
0,01900
0,00650
0,00800
0,00900
0,00600
0,00800
0,00900
0,00575
0,00675
0,00300
0,00650
0,00850
0,00600

ON THE BRAIN AND NERVOUS SYSTEM.

247

DIMENSIONS

OF

THE MEDULLA OBLONGATA IN FISHES.

NAMES OF FISHES.

MEASUBES

Of the Medulla
Oblongata,

Petromyzonßuvialis (lesser lamprey)
Squalus carcharias (white shark) .
S. acanthias (aguilat) . . , .

Raj/a clavata (ray)

R. rubns (red ray)

Acipenser sturio (sturgeon)
Esox luetics (pike) . .

Cyprinus carpio (carp)

C. tinea (tench)

Gadus morrhua (cod) ....
Cr. eglefinvs (haddock) . . . . ,

G. merlangus (whiting)

Pleuronectes maximus (turbot) .

P. solea (sole)

Mur Ciena anguilla (eel) ....
M, conger (congor eel) . . . . ,
Perea fluviutilis (perch) . . . ,
Trigla lyra (flying -fish) ....
Lophius piscatorius (frog- fish)

Metre.
0,00400
0,01400
0,00900
0,01600
0,01600
0,00850
0,00900
0,00600
0,00550
0,01000
0,00650
0,00600
0,00800
0,00500
0,00600
0,01100
0,00550
0,00700
0,00800

248

ON THE BRAIN AND NERVOUS SYSTEM.

DIMENSIONS

or

THE MEDULLA SPINALIS IN FISHES.

NAMES OF FISHES.

Felromyzonfluvial'is (lesser lamprey)
Sguahts carcharias (white shark) .
5. acanthins (aguilat) ....

RuT/^ clavata (ray)

R. rubus (red ray)

Acipenser sturio (sturgeon) . . .

Esox lucius (pike)

Cyprinus carpio (carp) ....

C. tinea (tench)

Gadus morrhua (cod) ....
G. eglefiniia (haddock) ....
G. meriangus (whiting) ....
Pleuronectes maximus (turbot)

P. solea (sole) , .

MurcEna anguilla (eel) ....
M. conger (congor eel) ....
Percafluviatilis (perch)
Trigla lyra (flying-fish) . . .
Lophhis piscatorim (frog-fish) .

MEASURES

Of the Medulla
Spinalis.

Metre.

0,00275
0,00700
0,00600
0,00900
0,00600
0,00400
0,00600
0,00200
0,00300
0,00575
0,00500
0,00300
0,00500
0,00233
0,00250
0,00700
0,00200
0,00400
0,00400

ON THE BRAIN AND NERVOUS SYSTEM. ^49

INSECTS.

^ SI 9. The general structure of the nervous system in this
class has been already mentioned (§ 204).

The larvae, in which the subject has been most completely
investigated,* have a brain, consisting of two ganglia, contain-
ed in a horny cavity larger than itself. The nervous cord,
which in red-blooded animals constitutes the medulla spinalis,
proceeds from this point along the abdomen, forming in its
passage twelve simple ganglia, from which, and from the two
ganglia forming the brain, the nerves derive their origin.'j-

VERMES.

§ 220. Excepting those animals which inhabit corals, and
the proper zoophytes, most genera of the other orders of this
class are found to possess a distinct nervous system ;^ although

* See Lyonet's excellent account of the larva of the Phalana Cossus, tab. 9, 10,
and 18. That of the silkworm by Swammerdam, tab. 28, fig. 3, (which is better
than Malpighi's representation) and by Bibiena, in the Comment. Instit. Bonon. torn.
V. pt. 1, tab. 4. That of the butterfly, by Bibiena, ibid.

t The nervous system of the larva of the stag-beetle, may be seen in Swammer-
dam, tab. 28, fig. 1 ; and in Röesel, torn, ii. tab. 8. That of the ephemera, in
Swammerdam, tab. 14, fig. 1, tab. 15, fig. 6. That of the male bee, ibid. tab. 22,
fig. 6. That of the musca chamaleon, in the diflPerent stages of its metamorphosis,
ibid. tab. 40, fig. 5, tab. 41, fig. 7. That of the larva of the musca putris, ibid. tab.
43, fig. 7. That of the louse, tab. 2, fig. 7. That of the lobster, Willis De Anima
Brutorum, tab. 3, fig. 1.

Humboldt's Verzuche über die gereizte Muskel und Nervenfase, vol. i. contain seve-
ral excellent anatomical and physiological remarks on the nervous system of some in-
sects, pp. 273, 286.

X See Jos. Mangili .De Systemate Nerveo Hirudinis, Lumbrici Terrestris, aliorumque
Vermium. Ticini, 1795.

The nervous system of the leech has been shewn by Redi, De Viventibus intra
Viventia, tab. 14, fig. 9 ; and Bibiena, Comment. Instit. Bonon. tom. vii. tab. 2, fig.
6, tab. 3, fig. 6. Bening's excellent work on the leech ; and Mangili's book may
also be consulted.

The nerves of the .slug are represented by Swammerdam, tab. 9, fig. 2 ; and those
of the helix pomatia, ibid. lab. 4, fig. 6 ; tab. 6, fig. 1 ; which may be compared
with the drawing by Spallanzani, in the Memorie delta Societa Ituliana, tom. ii, pt. 2,
p 545.

^50 ON THE BRAIN AND NERVOUS SYSTEM.

former anatomists have expressly declared, in several in-
stances, that no such parts existed.* The structure and dis-
tribution of the nerves possess in many cases a surprising ana-
logy to those of insects. The nervous system of the sea-mouse,
{aphrodite aculeata) for example, is very similar to that of the
larvae.-f In others it is more anomalous : thus, in the cuttle-
fish, two large nervous chords arise from the brain, and form
in the breast two club-shaped ganglia ; from which numerous
nerves proceed.^

In the class of insects, and of vermes, the upper ganglion of the
nervous chord, which represents the brain, is usually placed near the
mouth or oesophagus ; which tube is surrounded by a nervous chord
proceeding from that ganglion.

In the first volume of the work of M. Serres, V Anut07me comparee
du Cerveaii, which obtained the prize adjudged at the Royal Institute
of France, in 1821, the Report of Baron Cuvier, on that production,
is inserted. That report contains, in the form of aphorisms, the
substance of M. Serres's work, which, proceeding from so distin-
guished an anatomist, cannot fail to form a valuable appendix to this
section on the brain and nervous system.

The spinal marrow is developed before the brain in all classes.

It consists first, in young embryos, of two cords, which are not
united posteriorly ; between these two portions a sulcus is left. These
two cords soon approximate and join at their posterior part ; the in-
terior, therefore, of the spinal marrow is hollow. This canal, which
may be designated by the name of ventricle, or canal of the spinal
marrow, is sometimes filled with a liquid, constituting dropsy of the
spinal marrow ; this disease is of freqvient occurrence in the embryos
of mammalia.

The canal becomes obliterated at the fifth month of the human
embryo, and the sixth of those of the cotv and horse, the twenty-fifth
day in the embryo of the rabbit, and the thirtieth in those of the cat
and dog. It is found in the lai^vos of frogs, until the anterior and
posterior limbs appear.

This obliteration takes place in all these embryos by the deposition

* See the remarks of Humboldt, in his work above quoted, p. 259 ; and Cuvier's
classical work, which I here quote once for all, torn. ii. p. 298.

t Pallas, Miscellanea Zoologica, tab. 7, fig. 13.

t Swammerdam, tab. 52, fig. 2. Monro, On the Physiology of Fishes, tab. 41,
fig. 3. Scarpa, loc. eitat. tab. 4, fig. 7. Tilesius, in Isenflamm and Rosenmuller's
Beyträge zur die Zergliederungskunst, vol. i. pt. 2, tab. 2.

ON THE BRAIN AND NERVOUS SYSTEM. 251

of successive layers of grey matter, secreted by the pia mater which
passes into this canal.

The spinal marrow in young embryos of all classes, is of the same
size throughout its whole extent ; there is no enlargement either ante-
riorly or posteriorly, as is the case with reptiles deprived of limbs (vi-
pers, adders, blind-wornns,) and most fishes.

Embryos, which want the enlargements of the spinal marrow, are
deprived of their anterior and posterior extremities. The embryos of
all mammalia, of birds, and of man, resemble, in this respect, the lar-
vae of the frog genus in general.

With the appearance of limbs coincides, in all embryos, the ap-
pearance of anterior and posterior enlargements of the spinal marrow.
This effect is especially remarkable in the larvae of frogs at the pe-
riod of its metamorphosis ; the embryos of man, mammalia, birds,
and reptiles, experience a metamorphosis, entirely analogous to that
of the larvae.

The animals which have only a pair of limbs, have only one en-
largement of the spinal marrow ; the cetacea particularly are examples
of this kind. The enlargement varies in situation according to the place
which the pair of limbs occupy on the trunk ; the enlargement of the
spinal marrow in the genus bipes is situated on the posterior parts, in
the genus bimanvs, on the contrary, on the anterior part.

In the cases of monstrosity, which the embryos of mammalia, birds,
and man, so often present, there are frequently found bipeds and bi-
mana, which, like the cetacea and reptiles we have just mentioned,
have only one enlargement, situated very near the pair of limbs which
remains.

The spinal marrow of fishes is slightly enlarged very near the
place which corresponds to their fins. Hence the jugular have this
enlargement behind the head, at the cervical region of the spinal
marrow, the pectoral, near the middle part, or dorsal, and the abdo-
minal, near the abdominal region of the spinal marrow.

The ßj/ in g-Jish is remarkable on account of the detached rays of its
pectoral, as also by a series of enlargements proportioned, both in
number and in size, to the size and number of these same rays to
which they correspond.

The electrical fish has a considerable enlargement, corresponding
to the nerve which is distributed to the electrical apparatus, (rai/ silu-
rus electiicus).

The class of birds presents very remarkable differences in the pro-
portion of these two enlargements.

The birds which live on the earth, as our domestic birds, and
those which climb trees, have the posterior enlargement much greater
than the anterior. The ostrich is a remarkable instance of this kind.

The birds which fly in the air, and which often make long journeys,
present an inverse arrangement ; viz., the anterior enlargement ex-
ceeds the posterior.

M. Gall said that the gpinal marrow was enlarged at the origin

ON THE BRAIN AND NERVOUS SYSTEM.

of each nerve ; M. Series does not think that this opinion is con-
firmed by the examination of the spinal marrow of vertebrated
animals, at whatever period of life, whether intra or extra uterine,
they are considered.

M. Gall thought these enlargements were analogous to the double
series of ganglia, which are substituted for the spinal marrow in ar-
ticulated animals.

This analogy is found, as some authors have already observed,
not in the spinal marrow, but in the intervertebrated ganglia.

These ganglia, which have not much engaged the attention of ana-
tomists, are proportioned in every class to the size of the nerves
which traverse them. They are much larger near the nerves which
go to the limbs, than in any other part.

The spinal marrow is extended to the extremity of the coccyx, in
the human foetus, till the third month. At this period it is on a level
with the body of the second lumbar vertebra, where it is inserted at
birth.

The human foetus has a cauda equina, which remains till the third
month of uterine life; at this period this prolongation disappears,
and its disappearance coincides with the ascent of the spinal marrow
in the vertebral canal, and the absorption of a part of the vertebrse of
the coccyx.

If the ascent of the spinal marrow be arrested, the human foetus is
born with a tail, which is exemplified by a great number of cases ;
the coccyx is then composed of seven vertebrse.

There is then a relation between the ascent of the spinal marrow
in its canal, and the cauda equina of the human foetus and of mam-
malia.

The more the spinal marrow rises in the vertebral canal, the more
the cauda equina diminishes, as in the pig, the wild-boar, the rabbit ;
on the contrary, the more the spinal marrow is prolonged, and
descends in its sheath, the more the tail increases in size, as in the
horse, ox, and squirrel.

The embryo of bats without a tail resembles, in this respect, that
of man ; it has at first a tail, which it quickly loses, because, in these
mammalia, the ascent of the spinal marrow is very rapid, and pro-
ceeds to a considerable height.

This change is very remarkable in the larvae of frogs, the larvae
preserves its tail so long as the spinal marrow exists in the canal of
the coccyx. At the time when the larvse is about to undergo a meta-
morphosis, the spinal marrow ascends in its canal, the tail disappears,
and the limbs are more and more developed.

If the spinal marrow be arrested in its ascent, the frog preserves
its tail as the human foetus.

The human foetus, that of bats and other mammaha, undergo a
metamorphosis resembling the larvse of frogs.

In those reptiles which have no limbs, (vipers, adders) the spinal
marrow resembles that of the larvae before its metamorphosis.

ON THE BRAIN AND NERVOUS SYSTEM. 253

In all fishes the spinal marrow presents the same characters ; it
often presents at its termination a slight enlargement.

Among mammalia, the cetacea resemble fishes in this respect.

The human foetal monsters, which have no lower extremities, ap-
proach, in this respect, cetacea and fishes.

The decussation of the corpora pyramidalia is visible in the human
embryo about the eighth week.

In mammalia the decussation becomes less and less apparent on de-
scending from the quadrunimia to the rodentia.

In birds there are only observed one or two corpora pyramidalia at
farthest, the decussation of which is distinct.

In reptiles there is no decussation.

In fishes the decussation does not exist.

The size of the spinal marrow and that of the brain are, in general,
in inverse ratio one to the other of vertebrated animals.

The human foetus resembles, in this respect, the inferior classes ;
the younger the foetus is, the larger the spinal marrow is and the
smaller the brain.

In some circumstances the spinal marrow and brain preserve a di-
rect relation in size ; thus, when the spinal marrow is straight, the
brain is also straight, which is particularly remarkable in serpents.
When the spinal marrow diminishes in length, and increases in size,
the brain increases in equal proportions, which is very remarkable in
lizards and tortoises.

In birds, the more the neck is lengthened the narrower is the spi-
nal marrow, and the more reduced in tissue is the brain.

This direct relation of size between the spinal marrow and the
brain, does not apply wholly to the encephalon ; it only takes place
with respect to the corpora quadrigemina.

The spinal marrow and corpora quadrigemina are exactly develop-
ed in direct ratio one to the other, so that the size or power of the
spinal marrow being given in one class, or in families of the same
class, we can exactly determine the size and power of the corpora
quadrigemina.

The same observation applies to the human foetus ; the younger it
is the stronger is the spinal marrow, and the more the corpora qua-
drigemina are developed.

The corpora quadrigemina are the first portions of the brain which
are formed ; their formation always precedes that of the cerebellum,
in the embryo of birds, reptiles, mammalia, and man.

In birds the corpora quadrigemina are only two in number ; and
they occupy, as is well known, tlie base of the brain.

On the commencement of incubation, they are, as in other classes,
situated on the superior surface of the brain, forming at first two
lobes, one on each side ; on the tenth day of incubation, a transverse
sulcus divides this lobe, and at this time there are truly four tubercles
situated between the cerebrum and cerebellum.

On the twelfth day a very singular motion begins, by which they
pass from the superior towards the inferior surface of the brain.

g,54 on THE BRAIN AlSTD NERVOUS SYSTEM»

During this motion the cerebrum and cerebellum, separated at
first by these tubercles, approach and terminate by acting against
each other, as is observed in all adult birds,

In reptiles, the tubercula quadrigemina are only two in number in
the adult state ; but on the fifteenth day of the larvae of frogs, they
are divided, as those of the bird, on the tenth day.

In this class the tubercles do not change their place ; they always
remain situated on the superior surface of the brain, between the
cerebrum and cerebellum, and their form is always oval.

\n fishes, the considerable space which the tubercula quadrigemina
occupy, has caused them to be considered, up to the present time, as
the cerebral hemispheres of the brain.

That which has contributed to make this error believed is, that
they are intercepted by a large ventricle, presenting a considerable
enlargement, analogous in its form and structure to the corpora striata
of the brain in mammalia.

These tubercles are always double in fishes, and their form ap-
proaches that of a sphere, slightly flattened internally.

In mammalia and man, the corpora quadrigemina are only two
in number during two thirds of the uterine life ; they are then oval
and hollow internally, as in birds, reptiles, and fishes.

At the last third period of gestation, a transverse fissure divides each
tubercle, and then they are only four in number.

The difference which these tubercles present in the different classes
of mammalia depends on the position which this transverse sulcus
occupies.

In man it generally occupies the middle part ; the anterior tuber-
cles are almost equal to the posterior.

In the carnivorous animals the sulcus passes more anteriorly,
which gives a predominance to the posterior.

In the rmninantia and rodentia the sulcus passes more posteriorly,
which gives a predominance to the posterior.

In some brains of the human foetus and of mammalia the tuber-
cles remain as they were in their uterine life, namely in two, in which
respect they resemble the brain of fishes and reptiles.

The tubercula quadrigemina in man and mammalia are, in the first
instance hollow, as in birds, reptiles, and fishes. Their cavity is ob-
literated in the same manner as the spinal marrow; that is to say,
by the deposition of layers of grey matter secreted by the pia mater,
which passes into its interior.

The corpora quadrigemina are developed in every class, and in
families of the same class, in the direct ratio of the size of the optic
nerves and eyes.

Fishes have the largest corpora quadrigemina ; the optic nerves
and eyes are also most developed in this class.

After fishes come, in general, reptiles, for the size of the eyes, optic
nerves, and corpora quadrigemina.

Birds are equally remarkable for the development of their eyes,

ON THE BRAIN AND NERVOUS SYSTEM. 255

as also for the size of their optic nerves and corpora quadrige-
mina.

In mammalia the eyes, optic nerves, and corpora quadrigemina
decrease from the rodentia to the ruminantia, from the ruminantia
to the carnivorous animals, the quadrumana, and man, who occu-
pies, in this respect, the lowest grade of the animal scale.

As the corpora quadrigemina serve as a base for the determina-
tion of the other parts of the brain, we have accumulated all the
facts respecting them.

Fishes having the largest corpora quadrigemina, have also the inter-
parietal portions the most marked.

After fishes come the reptiles, then the birds ; lastly, among mam-
malia, the rodentia have the greatest inter-parietal portions ; then
come the ruminantia, the carnivorous animals, the quadrumana, and
man, in whom these are only occasionally met with.

It will appear singular that the cerebellum is not formed till after
the corpora quadrigemina ; but there is no exception to this fact in
any class.

In fishes the cerebellum is formed of two very distinct portions :

Of a middle lobe, arising from the ventricle of the corpora qua-
drigemina.

Of lateral layers proceeding from the corpus rectiforme.

These two portions are isolated, disjointed in every class of fishes.

The great difference which the cerebellum of the higher classes
presents depends on the union of these two elements, one of which
preserves the name of processus vermiformis superior cerebelli, and
comes, as in fishes, from the corpora quadrigemina ; whilst the other,
coming from the corpora rectiformia, constitutes the hemispheres of
the same organ.

Although united, these two elements are entirely independent of
each other.

The processus vermiformis superior cerebelli (middle lobe) and
the hemispheres of the same organ are developed in every class in
the inverse ratio of each other.

In the families composing the class of mammalia, the same relation
is exactly observed ; hence the rodentia, the ruminantia, the carnivo-
rous animals, the quadrumana, and man, have this process, and the
hemispheres of the cerebellum developed in the inverse ratio of each
other.

The spinal marrow is developed in all the classes in direct propor-
tion to the volume of the middle lobes of the cerebrum, and in the
inverse ratio of the hemispheres.

These general facts are especially important in estimating the
relations of the tuber annulare.

The tuber annulare is developed in the direct ratio of the hemis-
phere of the cerebrum, and the inverse ratio of the middle lobe.

The tuber annulare is developed in the inverse ratio of the corpora
quadrigemina and spinal marrow.

256 ON THE BRAtN AND NEllVOUS SYSTEM.

The iJialami nervorum opticorum do not exist in fishes ; that which
has been mistaken for them being only an enlargement peculiar to
the corpora quadrigemina.

In reptiles, birds, mammalia, and man, the size of the thalami is in
direct ratio to the size of the cerebral lobes, and the inverse ratio of
the corpora quadrigemina.

In the human foetus the proportion is the same, the corpora qua-
drigemina decreasing as the thalami increase. In the fcetuses of
other mammalia, as well as those of birds and frogs, this inverse pro-
portion also takes place.

The pineal gland exists in the four classes of vertebrated animals ;
it has two sets of poedicimale, one coming from the thalami, the
other from the corpora quadrigemina.

The corpora striata do not exist in fishes, reptiles, and birds.

In mammalia their development is proportioned to the cerebral
hemispheres.

The hemispheres are developed in the direct ratio of the size of
the thalami and corpora striata.

In fishes they form a simple rounded bulb, situated in front of the
corpora quadrigemina, where the dura cerebri are lost.

In fishes, reptiles, and birds, the cerebral lobes constitute a solid
mass without ventricles.

The ventricular cavities are peculiar to mammalia and man.

A curious inverse proportion is observed in this respect between
the three inferior classes and mammalia, with respect to the corpora
quadrigemina and the cerebral lobes.

In the three inferior classes the corpora quadrigemina have ven-
tricles ; the vertebral lobes are solid, and have none.

In the mammalia and man, on the contrary, the corpora quadri-
gemina are solid, and the cerebral lobes have large ventricles.

In the three inferior classes the cerebral lobes have no convolutions ;
in the mammalia, on the contrary, the convolutions appear with the
cavity of the lobes.

There is no cornu ammonis in reptiles, fishes, or birds.

It exists in all the mammalia ; it is more developed in the roden-
tia than in the ruminantia, and in the latter than in Carnivora, qua-
drumana, and man.

M. Serres has not met with the hippocampus minor in any class
of the mammalia. It is also sometimes wanting in man.

The fornix is wanting in fishes and reptiles. It is also wanting
in most birds ; but a rudiment of it is found in some, as the parrots
and eagles.

In the mammalia it is developed in the same proportion as the
cornu ammonis.

It is larger in the rodentia than ruminantia, and in the latter than
the Carnivora, quadrumana, and man.

There is no appearance of the corpus callosum in the three inferior
classes.

ON THE BRAIN AND NERVOUS SYSTEM. 257

The corpus callosum, as well as the pons varolii, are peculiar to
mammalia. The corpus callosum is developed in direct proportion
to the size of the corpora striata and hemispheres. It increases pro-
gressively from rodentia and man.

The corpus callosum is developed in direct proportion to the de-
velopment of the tuber annulare.

The hemispheres, taken as a whole, are developed in the direct ratio
of the hemispheres of the cerebellum, and in the inverse ratio of its
superior vermiform process.

The cerebral hemispheres are developed inversely, as the spinal
marrow and corpora quadrigemina.

The nerves do not arise froiTi the brain, to be distributed to the
different organs of the body, as has been generally supposed ; but
they proceed from these organs to the brain and the spinal marrow,
for the purpose of communicating with these nervous centres.

M. Gall has stated, that the grey is formed before the white mat«:
ter ; this opinion is not correct, as far as the spinal marrow is con-
cerned.

M. Cuvier first proved, that in the genus asterias the nervouS
■system is composed of white, without any grey inatter.

During the incubation of the chick, the first rudiments of the spinal
marrow are observed, composed of white matter ; the grey does not
appear till a later period. -

In the human foetus, and that of mammalia, the white matter ip
»constantly observed to appear before the grey in the spinal marrow ;
but in the cerebrum, properly so called, this order, as to the appear-
ance of the two substances, is reversed.

Hence the optic thalami and corpora striata are only enlargements
in the young foetus composed of grey matter ; the white not appear-
ing till a later period.

The corpora striata cannot be said to exist in the human foetus,
because the striae of white matter are not then formed.

The striae of white matter, which are found in the fourth ventricle
of the human subject, do not appear till the twelfth or fifteenth month
after birth.

g5§

CHAPTER XVII.

ON THE ORGANS OF THE SENSES IN GENERAL, AND ON THAT
OF THE SENSE OF TOUCH IN PARTICULAR.

I 221. Few subjects in comparative anatomy and physiology
have given rise to more various and contradictory opinions
than the organs of sense in some classes of animals.* Much
misunderstanding on this point has clearly arisen from the
inconsiderate and unconditional application of inferences drawn
from the human subject to animals. Thus it has been sup-
posed that those which possess a tongue, must have it for the
purpose of tasting ; and that the sense of smell must be want-
ing, where we are unable to ascertain the existence of a nose.
Observation and reflection will soon convince us, that the
tongue, in many cases (in the ant-eaters among the mammalia
and almost universally in birds), cannot from its substance
and mechanism be considered as an organ of taste, but must
be merely subservient to the ingestion and deglutition of the
food. Again, in several animals, particularly among insects,
an acute sense of smell seems to exist, although no part can
be pointed out in the head which analogy would justify us in
describing as a nose.

§ 222. However universally animals may possess that feel-
ing, which makes them sensible to the impressions of warmth

* Much useful information on the organs of sense, and indeed on comparative
physiology in general, may be found in F. Boddaert's Natuurkundigen Beschouwing
der Dieren. Utrecht, 1778, 8vo. ; and on the relation of the senses in the different
classes of animals, the reader may consult Dr. Troxler's Versuche in der Orga-
nischen Physik. Jena, 1804, 8vo.

ON THE ORGANS OF THE SENSES. ' ^H^f

and cold, very few possess, like the human subject, organs
exclusively appropriated to the sense of touch, and expressly
constructed for the purpose of feeling, examining, and ex-
ploring the qualities of external objects.

This sense appears, according to our present state of know-
ledge, to exist only in four classes of the animal kingdom j
viz. in most of the mammalia, in a few birds, in serpents, and
probably in insects.

MAMMALIA.

§ 223. The structure of the organ of touch is the most per-
fect, and similar to that of the human subject, in the quadru-
mana. The ends of their fingers, particularly of the posterior
extremities, are covered with as soft and delicately organized
a skin, as that which belongs to the corresponding parts in
man.

Several of the digitata are probably provided with this
sense. The organization of the under surface of the front
toes of the racoon, (ursus lotor) and the use which the animal
makes of those parts, prove this assertion.

It is not so clear that we are authorized in considering the
snout of the mole^ and pig,^ not to mention the tongue of
the solidungula and bisiilca,% or the snout of these and other
animals,! as true organs of touch, according to the explana-
tion above laid down. Much less can we suppose the long
bristly hairs, which constitute the whiskers of the cat kind,
and other mammalia, to be the organs of touch in the sense we
are now considering, although they may be serviceable when
they come in contact with any object, in warning, and making
the animal attentive. The seal, for instance, has a very long
infra-orbital nerve, consisting of about forty branches, which
are distributed to the projecting lip. I have traced many of

* Derham's Pkysico Theology, p. 206, not. 60.

t Darwin's Zoonomia, torn. i. p. 162.

t Buffon, Hiitoire des Oiseaux, torn. i. p. 47. '

$ Buflbn, Hiitoire Nuturelle, torn. iii. p. 360. "

s 2

S60, ON THE OUGANS OF THE SENSES.

their terminations to that part of the integuments in which
the bulbous roots of their strong whiskers are inserted.*

§ 224. There would be more reason for ascribing this
sense to the proboscis of the elephant, and to the soft, unci-
form, and always moist point of the upper lip of the rhino-
ceros.

• I think, however, that the ornithorhynchus clearly possesses
an organ of touch. In this curious animal, as in the duck,
&c., the sense in question resides in the integuments which
cover the expanded portion of its jaws, particularly the upper
one; this part is most copiously supplied with nerves from
the fifth pair, and chiefly from its second branch, distributed
just in the same manner as they are on the corresponding
parts of the swimming birds.t

- BatB have been supposed to possess a peculiar power of perceiving
external objects, without coming actually into contact with them.
In their rapid and irregular flight amidst various surrounding bodies,
they never fly against them ; yet it does not seem that the senses of
bearing, seeing, or smelling, serve tliem on these occasions, for they
avoid any obstacles with equal certainty when the ear, eye, and nose,
are closed. Hence naturalists have ascribed a sixth sense to these
animals. It is probably analogous to that of touch. The nerves of
the wing are large and numerous, and distributed in a minute plexus
between the integuments. The impulse of the air against this part
■may possibly be so modified by the objects near which the animal
passes, as to indicate their situation and nature.

Certain species of apes {tlte sapajous) are furnished with the
greatest number of organs of touch ; not only are their hands and
/eet adapted to this sense, but also the lower part of their tails. It
must be observed, however, that the fingers of their hands are op-
posed with difficulty to the thumb, which is sometimes altogether
Wanting ; besides both the, toes and fingers are with difficulty sepa^
):ated from each other. With respect to the tail, the number of ver-
tebrae which compose it is greater in a given space than in the same
space of the tails of apes which are not prehensile.

Man, who has only a rudiment of the sub -cutaneous tail, and
whose feet are formed in a 'manner peculiarly adapted to the station

* See Darwin, he. cit. Wiedemann, in the Gotting. gel, Anzeigen, 1798, p. 210.
Albers, ibid. 1803, p. 603 ; and Vrolik, Ovar het nut der Knevels by viervoetige
Dieren. Amst. 1800, 8vo. Andral, in Majendie's Journal de Physiol, torn. ii. p. 74.

f See Plate I. k, 1, m, t.

ON THE ORGANS OF THE SENSES. 2GI

and progression of a biped, is, with respect to the number of parts
formed for the sense of touch, less advantageously furnished than
some species of apes ; but the deficiency in point of number is
recompensed by the perfection of the form of his hand, which ena-
bles him to touch a globular surface, in almost all its points, on
account of the length of the thumb in proportion to that of the-
fingers, and the possibility of separating the thumb from the fingers,
and the fingers from each other. The structure of the skin is also
more perfect, the thickness of the sub-cutaneous adipose substance,
the breadth of the extremities of the fingers, the fine texture of the
cutis, the size of the nervous papillae, the thinness of the epidermis,
and the size of the nerves at the extremities of the fingers, are all,
circumstances which give peculiar delicacy and perfection to this
organ. Some species of apes, with prehensile tails, possess a similar
modification of the organ of touch, but it is confined to the hind feet
and tail. Many mammalia have the organ of touch situated in the
hips, as the horse, in which these parts are much developed, move-
able, and furnished with many nerves ; or, what is more singular, in
the nose, as the tapir and elephant, the prolonged nose of which
latter animal terminates in a flexible, fleshy, papillary edge, without
cuticle, divided into two parts, one at the extremity of the nostrils,
and the other prolonged to the dorsal or superior line into an ap-
pendix shaped like a finger ; this is called its trunk.

The mole and pig have the nose formed for feeling, but not for
distinguishing the shape of external objects.

BIRDS. '

§ 225. The structure of the organ of touch in the orni-
thorhynchuSf which has been just described, is exactly similar
to that oi geese and ducJcs. The bill of these birds is covered
with a very sensible skin, supplied with an abundance of
nerves, from all the three branches of the fifth pair.* This
apparatus enables them to feel about for their food in mud,
where they can neither see nor smell it.

Birds are much less favoured in respect to organs of touch than
mammalia ; one extremity of their bodies being occupied with the
bill, and the other with a sort of oar or rudder. The anterior
appendices are organs of mere locomotion, and the remaining portion
of the body, or the extremities of the posterior appendices, serve to
give them a firm position on their two legs. We find, however, that
in these animals the toes are more articulated than in mammalia,
that they are in a great degree capable of being separated from each.

• See Plate LV. c and f, to o. -

ON THE ORGANS OF THE SENSES.

Other, that the papillae of the cutis are well defined, and the nerves"
with which they are furnished considerable. It may be inferred,
therefore, that the feet of birds would be tolerably perfect organs of
touch, if they were not used as organs of locomotion, and that the
less they are used for the latter purpose, the more perfect would be
the sense of touch. Accordingly we find that parrots take up their
food with their feet, and convey it to their mouths. In birds of
prey the sense of touch is probably more acute, as their feet are
Jittle used for progression. In the gallinaceous birds, whose feet are
constantly on the ground, and in the ostrich and cassowary, which do
not fly, the epidermis is thickened, and its sensibility consequently
diminished.

AMPHIBIA.

§ 226. It has been said with more of point than of physi-
ological accuracy with respect to serpents,* that their whole
body is a hand, by which they gain just notions of the tan-
gible properties of bodies. According to Hellman, who has
investigated this subject, their slender bifurcated tongue
serves the purposes of touch.*!'

There, are some differences in respect to the degree in which dif-
ferent classes of reptiles may be supposed to possess some approxi-
mation to the organ of touch. The land and sea tortoises may be
supposed to possess the least sensibility in this respect, on account of
the shortness and close junction of their toes. The crocodiles, though
the structure of their toes is somewhat more adapted to the sense of
touch, resembling in this respect the river tortoises, whose toes are
well separated, cannot however be supposed capable of feeling the
form of external objects. This is the case also with the greater part
of the lizards, and especially those species which, by the diminution
of their members, become almost true serpents. Even in those, whose
toes are long and separated, the structure of the skin leads us to con-
clude that they are merely organs of locomotion. In the geckos,
however, and still more in the chameleons, we may suppose the sense
of touch to exist, since they clasp the branches of trees with their
toes, and even with their tails, which are prehensile. The number of
vertebrae which compose the tail of the chameleon, are proportionally
greater than in a lizard of the same size, and the skin which covers
both the tail and the toes of that animal seems to be softer than the
integuments in other parts of the body.

The great number of vertebrae which form the vertebral column of

* Girtanner, in his exposition of the Darwinian system, pt. 1, p. 124.
t A. Hellman, über den Tastdnnder Schlangen. Götting. 1817.

ON THE ORGANS OF THE SENSES, 26S

serpents seems a favourable structure for an organ of touch *, but the
scaly integuments of these animals renders it improbable that they can
judge of the form of external objects. Those species, however, which
can climb trees, and coil themselves round the branches of trees, have
a structure better adapted to this sense, since they have a greater
number of vertebrae in a given space than the other species, espe-
cially towards the posterior part of the body.

FISHES.

§ 227. Concerning this class it may be remarked, that
most of them possess an acute feehng on the ahdomen, and
in the hps,*" analogous, perhaps, to the sense of touch-

INSECTS.

§ 228. All the observations and investigations respecting
the structure of the antennae, those peculiar organs which
exist universally in the more perfect insects, and the use
which these animals generally apply them to, lead us inevitably
to the conclusion, that they really are proper organs of touch ;
by which the animal examines and explores surrounding ob-
jects.f Such organs are particularly necessary to insects, on
account of the insensibility of their external coat, which is ge-
nerally of a horny consistence ; and also from their eyes being
destitute, in most instances, of the power of motion.

VERMES.

§ 229. It seems more doubtful whether the tentacula of se-
veral vermes, and particularly the arms of the cuttle-fish,'^
can be considered as organs of touch, in the more limited
sense to which we have confined that word.§

• Lacepede, Histoire Naturelle des Poissons, torn. i. Discourse, p. 65.

t See Lehmann De Antennis Insectorum, Diss, 1, 2. Lond. 1799, 8vo. ; and
Knock's Neue Beyträge zur Insectenkunde, pt. 1. Leipzig, 1801, 8vo. p. 33.
Kandohr on the organs of touch in the bee in the Mag. der Berliner Naturf. Freunde,
1810, p. 287.

X Buffon, Histoire Naturelle, torn. iii. p. 360.

$ See Lehmann JJe Hensihus externis Animalium exsanguium. Goetting. 1798,
4to. p. 43. F. I. Schelver Versuch einer Naturgeschicte der Sinneswerkzeage hey den
Intecten und Wurmen. Goett. 1798, 8vo. p. 28; and Draparnaud, Tableau des
Mollusques Terrestres et Fluviatiles de la France, Montpellier, 1801, Bvo. p. 8,

264.

CHAPTER XVIII.

ON THE TONGUE.

§ 230. We are not justified in considering the tongue as an
organ of taste in all animals, because it is subservient to that
function in the human subject, and in many other instances.
We have already observed, that this organ, in many cases,
merely serves for taking in the food ;* and it is at least very
doubtful whether it possesses the sense of taste in several
others. Yet, on the contrary, we should not be warranted in
denying the existence of the sense in these animals, nor even
in such as are entirely destitute of a tongue: for this function
may be exercised by other parts. I have seen an adult, and
in other respects well-formed man, who was born without a
tongue. He could distinguish nevertheless very easily the
tastes of solutions of salt, sugar, and aloes, rubbed on his
palate, and w^ould express the taste of each in writing. Why
then may not those animals, which either have no tongue, or
one not calculated for an organ of taste, possess this sense in
some of the neighbouring parts ? I cannot however agree
with that ingenious anatomist Grew,+ when he considers the
internal surface of the three first stomachs of the bisulca to
be an organ of taste ; particularly since Wepfer and others
have remarked the enjoyment which is connected with the se-

* The lingual bone (os hyoides) of the three first classes of animals, varies accord-
ing to the different methods in which they take their food. Many excellent remarks
on this subject may be seen in Fab. ab Aquapendente De Larynge, p. 276 ; and irj
Casserius De Vocis Organis, with excellent delineations.

t See his Qom'parative Anatomy^of Stomachs and Guts, p. 26,.

ON THE TONGUE. 235

cond mastication of the food in ruminating animals. Less,
however, can be concluded with any certainty ä priori on this,
than on any of the five senses.

MAMMALIA.

§ 2ol.* No animal possesses a tongue exactly like that of
the human subject. The form of the organ differs consider-
ably in the simice, being longer and thinner ; and the papillae^
which cover its upper surface, are very different.

Thus, the length of the tongue of the commonest kind of
tailless ape, (simia sylvanus) which now lies before me, is three
times greater than its breadth. It has three papillce pe-^
iiolatcB, or fungiformes, at its posterior part, arranged in the
form of a triangle. Before these, and along the two sides of
the tongue, are about two hundred papillce obtnsce, appearing
like white grains. These are not all of the same size ; but
they may be distinguished from the papillcz conicce, which
cover the rest of the tongue's superior surface, much more
easily than in the human tongue.

§ 232. Most of the herbivorous mammalia, particularly
among the bisulca, have their tongue covered with a firm and
thick cuticular coat, called epithelium ; which forms number^
less pointed papillae directed backwards. These must assist,
according to their consistence and direction, at least in the
animals of this country, (Germany) in tearing up the grass.^
Animals of the catf kind have their tongue covered with
sharp and strong prickles, which must enable the animal to
take a firm hold. Similar pointed processes are found in
some other animals ; as in the bat-JcindX and the opossum.

In the tongue of the opossum I have found the centre of

• See Reuter De lingua Mammalium et Avium. Regiom. 1820.
1 Daubenton, vol. ix. tab. 15, of the panlher ; fig. 3 of the cat ; tab. 22, fig. 2,
3, of the lyrix.

t Ibid. vol. X. fig. 15 of the vampire.

Pallas, Spicileg, vol. iii. tab. 2, fig. 5, 6, of the vespertilio cephalotes.

266 ON THE TONGUE.

the anterior extremity beset with strong papillae, rougher than
those which are found in the cat.

There seems to be no doubt, that in all the mammalia which
we have now considered, the tongue is an organ of taste, at
least towards its anterior part.

The toothless animals, on the contrary, as the ant-eater and
manis, which swallow their aliment whole, have a long worm-
like tongue, which is obviously capable of no other use than
that of taking their food.

The tongue of a two-toed ant-eater, which I dissected, was
three inches and a half long, and no larger than a crow-quill
at its root. It was, generally speaking, cylindrical, but mark-
ed with a scarcely perceptible groove on its superior surface.
Two very small foramina coeca were found near the root.
The lingual bone was strong, but not remarkably large, and
in shape like a horse-shoe. Its muscles, on the contrary, as
the geniohyoidei, mylohyoidei, and particularly the genioglossi,
were remarkably large and strong.

As we are now considering the tongue in its office of assist-
ing in taking in the food, this seems to be the proper place
for noticing the worm, as it is called, (lytta) of the dog's
tongue. It is a tendinous fasciculus of fibres running length-
wise under the tongue, as far as its apex, and lying rather
loose, in a kind of membranous sheath, without being connect-
ed, like a true tendon, to any of the neighbouring muscles.
By an old prejudice, which has subsisted at least since the
time of Pliny, its extirpation is considered as a preservative
against hydrophobia.* Casserius thought that it assisted
dogs in lapping up fluids in the peculiar way which they do ;
and his opinion is supported by this circumstance, that an
opossum, which I kept alive for some time, and which took
fluids in the same manner as dogs do, had a similar part under
the tongue.

* Concerning the structure of this curious, and in some respects enigmatical part,
see Morgagni De Sedibus et Causis Morborum, torn. i. p. 67. Venet. 1761.

ON THE TONGUE. 267

BIRDS.

§ 23S. All birds possess a tongue, for even the pelican,
{pnoerotalus) in which its existence has been denied, possesses
a manifest rudiment of the organ. Probably, however, it
serves the purpose of an organ of taste in very few genera.
Yet this is the case with some predacious and swimming
birds, as also with most of the psittaci; which possess a soft
thick tongue covered with papillae, and moistened with a sali-
vary fluid ; they really taste diiferent fluids, and soft kinds of
food, and select that which is the most agreeable.

§ 234<. In several other birds, on the contrary, the tongue is
horny, stiff", not supplied with nerves, and consequently unfit
for an organ of taste. One striking example will supply the
place of many. The tongue of the toucan (ramphastos) is some-
times several inches in length, yet scarcely two lines broad at
its root. It has the appearance, throughout, of a piece of
whalebone ; and its margins are fibrous.

^ 235. The form * and mechanism of the tongue vary much
in the different genera and species of this class. Two instances
deserve particular notice ; that of the wood-peckerf and the
cock of the woods. The tongue of the former bird is gene-
rally said to be very long, but it is not so. That part which
corresponds to the tongue of other birds, is remarkably short,
it is merely a sharp-pointed horny portion, with its sides
barbed. Behind this is a very singular os hyoides, of a slen-
der appearance, but having very long crura. It consists of
five cartilaginous portions ; viz. one single piece and two
pairs. In the quiescent state of the organ the former lies in
a fleshy and very extensile sheath of the bill. The first pair
of cartilages is articulated with this, and they are placed at
the sides of the neck. The second pair, commencing from

• See the plates in J. C. Schoeflfer's Elementa Ornitholflgica. Ratisbon, 1774,
4to.

t Huber De lingua Pici viridis, Stuttg, 1821.

^68 ON THE TONGUl:.

these, run completely over the cranium, under the integu-
ments, and advancing from behind, forwards, their converging
extremities are placed together in a kind of groove, and com-
monly terminate anteriorly, by an attachment to the right side
of the upper jaw. This posterior pair of cartilages may
therefore be compared to steel springs, which actuate the
whole organ. This is an elegant example of the great share
which mere elasticity possesses in the performance of some
functions of the animal economy. When the tongue is to be
darted out, the anterior pieces are drawn together and enter
the sheath of the single portion, extended for their reception.
The tongue is thus elongated, and admits of being thrust out
some inches.*

The tongue of the cock of the woods is still more singular ;
that organ, together with the larynx, lies deep in the oesopha-
gus, but admits of being quickly elevated and thrust forth by
means of considerable muscles.*|-

AMPHIBIA.

I 236. We shall select a few examples of the chief varieties
in this class of animals.

The crocodiles tongue (the very existence of which has been
denied from the time of Herodotus down to Hasselquist) is
small, possesses very little motion, and is in a manner adhe-
rent between the two sides of the lower jaw.:]: The salaman-
der resembles this. A very different structure is presented in
the curious tongue of the chameleon, the mechanism of which
may be compared, in some respects, with that of the wood-

* See Mery, in the M£moiresde I'Acad, des Sciences, 1709, p. 85. Waller, in the
■Philos. Trans, vol. xxix. p. 509 ; and Wolf, in Voigt's Magazin, pt. 2, of the new
series, p. 468.

t Frisch, Vögel in Deutschland, tab. 108. Schneider's Commentary on the Works
6f Frederic 11. tab. 2 3 and Gilibert, Medecin Naturaliste. Lyons, 1800, 8vo. p.
294.

i C. G. De Rhoer De Fide Herodoti rite astimanda, in the Verhandelingen van
Teylers tweede Genootschap, pt. 7, p. 104. L. Y. Hämtnen De Herniis, p. 105.
Nouvelles de la Republique des Lettres, Oct. 1688, p. 1125.

ON THE TONGUE. 269

pecker. Yet its form is vei'y different ; for the anterior extre-
mity of the organ is club-shaped ; and is hollowed out on its
upper surface.*

The tongue of some testudines is thickly covered on its an-
terior margin with long fibrous papillas-i-

The soft, flat, and fleshy tongue of the frog, lies, in a quies-
cent state, in a direction from before backwards. It is firmly
attached behind the arch of the lower jaw, and its loose end is
turned backwards, so that the semilunar notch of its anterior
margin corresponds to the rima glottidis. They seize their
prey by turning the tongue forwards, and thrusting it out of
the mouth.

The tongue of the chameleon displays a very curious mechanism.
It is contained in a sheath at the lower part of the mouth, and has its
extremity covered with a glutinous secretion. It admits of being
projected to the length of six inches, and is used in this manner by the
animal in catching its food, which consists of flies, &c. It is darted
from the mouth with wonderful celerity and precision, and the viscous
secretion on its extremity entangles the small animals which constitute
the food of tlie chameleon,

§ 237. The tongue of the serpent is attached and situated in
the same manner as in \}i\Qfrog,\ but it is round and slender,
its apex is bifid, and the root rests in a kind of fleshy sheath,
being capable of protrusion and retraction at pleasure.^

FISHES.

^ 238. There is little to be said concerning the tongue of

* Besides the works which have been already quoted on the anatomy of this ani-
mal, see Hussem, in the Verhandelingen van de Maatschappye te Haarlem, vol. viii.
pt. 2, p. 228. Duvernoy, in the Bulletin de la Soc. Philom. torn. iii. ; and Miller,
Iconei Animal, et Platitar. tab. 2.

t I have observe'd this in the testudn graca from Mogadore. The form of the os
hyoides in the testudines may be seen in Caldesi, tab. 8.

X Seetzen, in Meyer's Zoologisch Archiv, pt. 2, p. 65.

5 Abbild. Naturhiitoriich. Gegenstände, pt. 4, tab. 37, in the boa and rattle-snake.
ITie curious os hyoides of serpents, with two cartilaginous portions running along the
trachea, is represented by Tyson, Philvs. Trans, vol. xiii. p. 68, fig. 5.

S70 ON THE TONGUE.

this and the two following classes. It is doubtful whether it
be an organ of taste, and in what degree it may serve that
purpose.*

It appears at least in fishes to possess no manifest papillae,+
and in many of this class is covered with teeth.

That which is commonly called the tongue, in some fishes,
as the carp, is a glandular body attached to the palate, and
extremely irritable in the Uving animal.J

INSECTS.

§ 239. The organ which is commonly considered as the
tongue of insects § merely serves for taking in the food.|| But
the accurate observations of professor KnochjH render it very
probable that the posterior pair of palpi, or feelers, possesses
the power of taste in several of this class.

VERMES.

§ 240. In the mouth of some moUusca,** and snails, an
organ is found, which has generally, from its situation, been
taken for the tongue. But none of the observations which
have been hitherto adduced respecting its functions, are suffi-
ciently decisive to justify us in setting it down as an organ of
taste.

* See Dumeril, Memoires de Zoologie et de V Anatomie compar^e. Par, 1807.

t JjiveBzim' s Osservazioni sulle Torpedini, p. 41,

J Observat. Colleg. privat, Amstelod. vol. i. p, 40.
- § Schelver, loco citato, p. 39. A. W. Knock, Neue Beyträge zur Insectenhimde,
pt. 1, 1801, 8vo. p. 40, tab. 1, fig. 30, in which the tongue of the May-beetle {scara-
bcEus melolontha) is represented.

II Loc. cit, p. 32, tab. 1, fig. 9, of the scarabaus Frischii; tab. 8, fig. 4, of the
scarabceus tmicolor.

% Swammerdam, of the cuttle-fish, p. 882, tab. 50, fig. 4, 5.
** Of the helix pomatia, ibid. p. 109, tab. 5, fig. 3.

271

CHAPTER XIX.

ON THE ORGAN OF SMELLING.

§ 241. Ihe sense of smelling prevails much more extensively
in the animal kingdom than that of taste, since it not only as-
sists several genera in selecting their food, which they have
not afterwards the power of tasting, but is also of service in
finding out proper objects for the satisfaction of their sexual
appetite. Yet there is much doubt I'especting the organs of
this sense in the two classes of white-blooded animals.

§ 242.* We can determine the degree of acuteness of this
sense by the inspection of the cranium in the four-footed
mammalia, (taking the term in its most extensive sense, in
which it will include the quadrumana and hats). Three cir-
cumstances principally determine our judgment on this point.

1st, The structure of the ethmoid bone, and particularly
the number and arrangement of those openings in its superior
or horizontal lamina, which transmit the filaments of the olfac-
tory nerve. 2ndly, The formation of the inferior conchae na-
rium, or turbinated bones. Srdly, The existence and relative
magnitude of those cavities of the internal nose, particularly
the frontal sinuses, which contribute to the organ of smelling.

§ 243. The hedgehog and mole, the animals of the weasel,
hear, dog, and cat-kinds, most of the hisulca, and the elephant,
afford examples of a very complicated formation of the ethmoid
bone, both in regard to the elegant structure of its cribriform

• F. C. Rosenthal, Diss, de Organo Olfaclus (juorundam Animaiium. Jena, 1802,
4to ; and CryplncB, 1807.

272 ON THE ORGAN OF SMELLING.

lamella, and to the wonderful convolutions of its turbinated
portions, which procure as large a surface as possible within
the confined space of the nasal cavity, for the application of
the Schneiderian membrane. All these animals are well known
for the remarkable acuteness of their sense of smelling.

The ethmoid bone is remarkably narrow, and imperfectly
developed in most of the quadrumäna. As there is not suffi-
cient space left for it between the orbits, which lie close toge-
gether, (§ 21)* it is placed deeper in the nose, so that the ol-
factory nerves descend between the orbital portions of the
frontal bone, as in a canal, the bottom of which is formed by
the cribriform lamella, small and inconsiderable, and perfo-
rated by few apertures.-f

The cetacea have no ethmoid bone ; and it is a matter
of doubt what pair of nerves contribute to the function of
smelling.

At the time when the author first published this work, he, as
well as other zootomists, believed that the cetaceous animals had no
olfactory nerves. Blainville and Jacobson, however, believe that
they have found them in the dolphin {delphinus delphis) situated in
the same part of the brain as in the human subject. See the Bulletin
de la Societe Philom. 1815, p. 195. Treviranus has also delineated
and described them in bis Biologie, vol. v. p. 342 ; but Otto and Ru-
dolphi, who have had frequent opportunities of examining the brain
of dolphins and Greenland tvhales, have not been able to detect the
_first pair, and doubt their existence in those animals.

. § 244. The conchce narium inferiores are more or less con-
voluted, in proportion to the greater or less complication in
the structure of the upper ones. They are remarkably large
in the bisulca ; % and much convoluted in most of the preda-

* In tVie skull of a cercopithecus capucinus in my possession, the partition between
the two orbits, which space in the human cranium is filled by the ethmoid cells, and
superior turbinated bones, contains a large opening, which in the recent state was
probably closed by a portion of periosteum.

t Josephi, Anatomie der Säugethiere, vol. i. p. 179, &c.

^ See Caspar Bartholin, Analecta Observationum, in his Specimen Historice Anata-
mic-p, tab. 3, fig. 3, 4, of the sheep ; and Morand, in the M6m. de I'Aead. des
Sciences, an 1724, tab. 24, of the ox. Sir B. Harwood's System of comparative
Anatomy. Camb. 1796.

ON THE ORGAN OF SMELLING.

273

cious animals.* They are both large and wonderfully com-
plicated in the seal.

§245. The frontal sinuses of the elephant \ are larger
than those of any other animal ; the pig, which has an acute
sense of smelling, comes next in order in this respect. I have
considered, in a more detailed manner, the structure of these
cavities in several genera and species of the different orders of
mammalia in my Prolusio de Sinubus Frontalibus, Goetting.
1779, 4to., where I have endeavoured to show, from compara-
tive anatomy, that their use is to strengthen the sense of
smelling, and that they are not subservient to the formation of
the voice. Most of the mammalia, which possess proper
horns, have these cavities extending more or less into those
processes of the frontal bone, on which the horns are formed :
this structure is particularly observable in the wild goat {capra
ibex). They are generally large in the bisulca, the solidun-
gida, and in most of the carnivorous mammalia. They are
absent on the contrary in the seal, in most of the rodentia^
and the cetacea. They receive in the sheep, as is well known,
the larvae of the oestrus ovis ; and cases are not very uncom-
mon in which other insects, particularly the scolopendra elec-
trica, have accidentally gained admission into them in the hu-
man subject, and have caused distressing and tedious symp-
toms.

§ 246. The anomalous structure of the elephant's proboscis,
or trunk, and the blowing-holes of the cetacea, must be no-
ticed here, as these parts constitute prolongations and external
openings of the nose.

The former organ consists of two canals, separated from
each other by an intervening partition. Innumerable muscu-
lar fasciculi, running in two directions, occupy the space be-
tween these and the integuments. There are fibres of a
transverse course, passing like radii from the canals to the in-

* Casp. Bartholin, hen citato, fig. 5, 6, of the Iwund (cants venaticus).
t Stukfly, in his ffintm-i/ nf the Spleen, p. 101, tab. 5, fig. 2,

274) ON THE ORGAN OF SMELLING.

teguments ; * and others, which run in a more longitudinal di-
rection, but have their extremities turned inwards.f The
former extend the trunk without causing any contraction of
the canals, the latter bend or contract it, and both tend to
bestow on it that wonderful mobility which it possesses in every
direction.

The blowing hole of the cetacea is not a peculiar organ,
distinct from the nasal openings, as several naturalists have
imagined, but one and the same with these.J It does not,
however, seem to be designed for an organ of smelling, but
merely to be subservient to respiration, and to the expulsion
of the water which enters the mouth with the food.§

Cuvier has given a more detailed description of the elephant's trunk
in the last vol. of his Legons d'Anat. comp. p. 283 — 289 ; and has also
represented the part in the 29th plate of the same volume.

The more longitudinal fibres are divided at short intervals by ten-
dinous intersections, which enable the animal to bend any part of the
organ, and to give it any requisite degree of curvature. The same
structure will confer a power of bending different parts of the trunk
in opposite directions ; indeed there is no kind of curvature which
may not be produced by these longitudinal fibres. These fasciculi
occupy the external surface of the organ. The transverse fibres are
not all arranged like radii round the canals ; but some pass across
from right to left, and must therefore affect the diameter of those
tubes by their action. The whole of these muscular fasciculi are
surrounded and connected together by a white, uniform, adipose
substance. The transverse ones are not more than a line in thick-
ness. If the number of these, which appear on a transverse section,
be ascertained ; and if those portions of the longitudinal fasciculi,
which pass from one tendon to another, be reckoned as separate
muscles, (for they must have a separate power of action) the whole
trunk will contain about thirty or forty thousand muscles, which will
account satisfactorily for the wonderful variety of motions which this
admirable organ can execute, and for the great power which it is ca-
pable of exerting.

The blowing-hole of the whale serves as well for respiration as

* Hist, des Animaux, torn. iii. tab. 22, fig. 9 ; Stukely, loc. cit. tab. 1, fig. 2.
t Hist, des Animaux, Zoc. cit. Stukely, tab. 5, fig. 1.

t This has been correctly stated by Tyson, in his Anatomy of a Porpoise, tab. 2^
fig. 8, 9.

$ Cuvier, in the Magazin Encyclopedique, an 3. torn. ii. p. 299.

ON THE ORGAN OF SMELLING. 275

for the rejection of the water which enters with their food. In con-
sequence of its situation at the top of the head, it is easily elevated
beyond the surface of the sea, while the mouth is usually entirely un-
der water.

The opening in the bones of the head is divided into two by a par-
tition of bone, and is furnished with a valve opening outwards. On
the outside of this opening are two membranous bags, lined with a
continuation of the integuments, and opening externally. The wa-
ter which the animal wishes to discharge is thrown into the fauces,
äs if it were to be swallowed, but its descent into the stomach is pre-
vented by the contraction of the circular fibres of the oesophagus. It
therefore elevates the valve placed at the entrance of the blowing-
holes, and distends the membranous bag, from which it is forcibly
expelled by surrounding muscular fibres. "

This apparatus occupies the situation which, in other mammalia, is
filled by the nose, which organ, together with the sinuses of the head,
the olfactory nerve, &c. is entirely wanting in these animals.

BIRDS.

§ 247. The nostrils open in the several genera of this class
in very different parts of the upper mandible ; in some, as the
'puffin, {alca arctica) the openings are placed at the margins
of the bill, and are so small, that they might be easily over-
looked. This may serve as an excuse for the erroneous re-
presentation of Buffon, that several birds are entirely unpro-
Tided with nostrils, and that they smell by means of the pala-
tine openings of the nasal cavity.*

§ 248. Birds have no proper ethmoid bone ; their olfactory
nerves pass through the orbits to the nose, and are distributed
on the pituitary membrane, which covers two or three pairs of
bony,t or cartilaginous J conchae nariuni (hullce turbinatce or
tubulatcB vesic(z)% of various forms and sizes.||

The olfactory nerve of birds comes off from the anterior extremity

* Histoire des Oiseaux, torn. i. p. 13.

t The crane has very large turbinated bones.

^ This is the case in the toucan (ramphaStvs).

§ They are excellently described under this name by Schneider De Osse Cribri
fcrmi, p. 180.

H See Strarpa's representation of the nerves of the nose in the froose, turheii, and
hrrim. De Andihi, et Olfartit, tab. 3.

T 2

276 ON THE ORGAN OF SMELLING.

of the frontal lobe of the brain, and has, therefore, some analogy
with the processus mamillaris of quadrupeds. It passes along a ca-
nal to the nose, and is distributed in a very beautiful and distinct
manner on the pituitary membrane in many instances, as in the
crane.

AMPHIBIA.

§ 249. The organ of smelling is less clearly developed in
this class of animals. Yet we discover two cartilaginous emi-
nences, which may be compared to the conchae of warm-
blooded animals.*

The origin and course of this nerve are much the same in reptiles
as in birds. In the turtle it is a large, strong, and fibrous nerve, and
its ramifications in the nose are easily traced.

FISHES.

§ 250. Most of these seem to have double nostrils on each
side, for the openings are furnished with a valve-like moveable
membrane, which appears like a partition. It was formerly
supposed, that this part served also for the organ of hearing'
in fishes ; and this erroneous opinion has been revived even
in modern times, but it cannot be necessary to refute such an
absurdity now.

§ 251. Behind these openings is generally found, instead of
conchae narium, a very elegantly plaited membrane, disposed
in semicircular folds, and having the olfactory nerves distri-
buted on it.t

INSECTS.

§ 252. Numerous facts have long ago proved that several

* Scarpa, tab. 5, in a Uirtle and viper.

f See representations of this part in the raia clavata, by Scarpa, tab. 1 , fig. 2 ; in
the skate, (raia batis) by Harwood, tab. 7 ; in the shark, by Stenonis, in his Speci-
alen Myologvz, tab. 7, fig. 1 ; in the squalus catulus, by Scarpa, tab. 2, fig. 6, 7 ;
iu the frog'ßsh, (lophius piscatorius) ibid. tab. 1, fig. 3 ; in the pike, by Casserius,
De Auditus Organis, tab. 12 ; by Camper, in his Kleine Schriften, pt. 2, tab. 2, fig.
1 ; Scarpa, tab. 2, fig. 1, 2; and Harwood, tab. 5, fig. 4; in the carp, ibid. tab.
2, fig. 4, 5.

Some

ON THE ORGAN OF SMELLING. 277

insects can distinguish the odorous properties of bodies even
at considerable distances. But the organ in which this sense
resides has not hitherto been clearly pointed out.*

Since all red-blooded terrestrial animals smell only through
the medium of the air, which they take in in inspiration, seve-
ral naturalists have supposed, that the stigmata of insects are
to be considered as organs of smelling.+ Others ascribe this
office, and with some probability, to the anterior pair of
palpi. J

VERMES.

§ 253. Several animals of this class appear to have the
sense of smelling, as many land-snails {helix pomatia,^ Sec).
IßvLt the organ of this sense is hitherto unknown ; perhaps it
may be the stigma thoracicum.

Some detached remarks on the organ of smelling, in particular fishes, are gived
by Morgagni in his Epist. Anat. p, 350. Padua, 1764, fol.
. * Rosenthal, über den Geriichsinn der Insecten im Archiv, für Physiologie, p. 427.

Ramdohr, übei' die Organe des Geruchs der gemeinen Biene, in the Mag. der
Berlin. In. Gesell, vol. v. p. 386.

t ITiis was the opinion of S. Reimarus, uher die Tribe der Thiere, p. 308, ed.
3rd. See also Dumeril^ in the Magazin Encyclopedique, an 3, tom. ii. p. 435.

t Knoch, in his Beyträge zur Insectenhunde, p. 32, tab, 1, fig. 8 ; and tab. 8,
fig. 3, of the scaraba'us frischii, and carahus unicolor.

i Swammerdam, p. 110.

zn

CHAPTER XX.

ON THE ORGAN OF HEARING.

§ 254. We should naturally expect to find an organ of hear-
ing in most classes of animals,* when we consider the various
services which this sense performs ; as, that of indicating the
approach of danger, of conducting predacious animals to their
prey, and of bringing the two sexes together for the purpose
of copulation, &c. Red-blooded animals, without any excep-
tion, possess this organ. Analogous parts are found in some
of the white-blooded ; and several others certainly can hear,
although the organ of that sense has not been hitherto ascer-
tained.

MAMMALIA.

§ 255. The four-footed mammalia are the only animals
which possess true external ears ; and, even in that class, se*
veral instances occur in which these parts are wanting; parti-
cularly among such as live in the water, or under ground.

* The following works may be consulted for an account of the organ of hearing
in the different classes of animals.

Casserius De Vocis Auditusque Organis, Ferrara, 1600, fol, (The part relating
to the ear is also contained in his Pentcestheseian.')

Perrault, Essais de Physique, torn. ii.

Geoffroy sur I'Organe de I'Ouie, &c. Amsterd. 1788.

Scarpa De Audita et Olfactu.

Comparetti, Observationes AnatomiccB de Aure interna comparata. Patav. 1789-4.

Monro's three Treatises on the Brain, Eye, and Ear, Edin. 1797-4.

Home, in the Philos, Trans. 1800, pt. 1.

Pohl, Expositio Anatomica Organi auditusper classes Animalium. Vindebon. 1818.

Weber De aure et auditu Hominis et Animalium. Leips. 1820.

ON THE ORGAN OF HEARING. 279

They are not met with, for instance, in most of the seals, in
the walrus, manati, duck-billed animal, {prnitliorliynchus) and
mole. On the contrary, some have been said to want exter-
nal ears, who really possess them, as the mavmota or mus citil-
lus. Another error has been committed, in representing the
ears of a species of hat belonging to this country, (Germany)
ipespertilio auritus) as double : whereas they are only of an
immense size. Still more erroneous is an observation of
Haller ; that these ears are to be considered as an accidental
monstrosity. The essential parts of the external ear agree on
the whole with those of the human subject ;* but their general
form is subject to great variety. In very few, except the
quadrumana, do they resemble those of man ; but this is the
case in the porcupine. The cartilage is stronger, and more
elastic in its structure in the human ear than in that of any
other animal, in proportion to its size. In some instances, as
in the opossum, {didelphis marsupialis) the ears are merely
membranous.

§ 256. The external auditory passage is furnished with a
valve in such animals as go frequently into the water, by
which they can close it when they dive. The water-shrew
(jsorex fodiens) affords an example of this structure. The
length, breadth, and direction of the meatus vary considerably
in the different genera. It is very long and singularly tortu-
ous in the duck-hilled animal.f

The cetacea are the only mammalia which have not a bony exter-
nal meatus. The tube is cartilaginous in these animals, and so small
that its external orifice will about admit a pin in the dolphin. It ar-
rives at the tympanum after a winding course through the fat, which
lies under the skin. It is probable that the sound gains admission to
the ear in these animals, rather through the Eustachian tube than
through this very narrow meatus externus. That tube opens at the
blowing hole, and is furnished with a valve that prevents the admis-
sion of the water, which the animal expels through this opening.

^ 257. It is hardly necessary to state, that all mammalia

* The lobulm of the external ear however is found in no animal but man.
t Home, in the Phibs. Trans, 1802, pt. 1, p. 70.

280 • ON THE ORGAN OF HEARING.

have a membrana tympanic a tympanum situated within this,
and an Eustachian tube passing from that cavity to the
fauces ; except in the cetacea, where it opens in the blowing
hole. The membrane is rather concave on its outer surface,
being slightly depressed in the middle. All the animals of
this class are furnished with the two fenestrts ; the fenestra
ovalis, which is filled by the base of the stapes ; the fenestra
rotunda, at which the scala tympani of the cochlea com-
mences.

^ 258. In the 7iorse and ass the Eustachian tube does not
open immediately into the larynx ; but into a sac peculiar to
this class of animals, which is situated on the lateral parts of
the lower jaw. These cavities then open by a long fissure,
provided with a cartilaginous valve, into the pharynx. Have-
mann found, in a horse fourteen years old, the cavity of the
left side twice its natural size, forming a considerable tumour
externally, and containing, besides a good deal of white
mucus, 136 cartilaginous concretions, of about the size of a
hazel-nut.*

§ 259. In most of the four-footed mammalia, there is con-
nected with the tympanum another cavity ; which, according
to the situation of the bony organ that contains it, must be
compared to the mastoid cell^ in the temporal bone of man.*!*

In several animals this organ forms a mere bony cavity,
{bulla ossea) viz. in the dog, cat, martin, squirrel, hare, and
some of the bisulca. Partial development of this structure is
to be seen in the cercopitheci. In the horned cattle, on the
contrary, and in the pig, the cavity is divided into cells by nu-
merous bony plates, which somewhat resemble the divisions in
a ripe poppy head4

* Bourgelat, Eiemensde I' Art. retulaaire. Par. 1769, p. 498.

Eudolpbi, Tlehclemcvkungen, vol. i. p. 77, vol. ii. p. 220.

"\'iborg, Sammlung von Abhandl. für Thiei-'drzte und Ockonomen, p. 240.

t Sommerberg, however, denies that the cavity can be so compared, and considers
the bulla ossea a part of the external meatus. See his QucBstio Physiologica quce et
q^laUs sit musculorum vis formmn osseam mutandi. Lond. 1801.

J Vesalii Anatomicarmn FallopiiObservatiotium examen. Venet. 1764, 4to. p. 20.

ON THE ORGAN OF HEARING. 281

§ 260. Warm-blooded quadrupeds have, like the human
subject, three* ossicida auditus ; which on the whole resemble
in form those of man. But the ducJced-billed animal, whose
structure in every respect is so anomalous, has only two ;i- and
on the contrary, one or two additional small bones are occa-
sionally found, particularly in some bisulca.X

The following is the passage to which the author refers as express-
ing his opinion on this subject. «' Anatomists generally describe a
fourth bone (the lenticulus, or os orhicidare) as intervening between the
long leg of the incus and the head of the stapes. Repeated and accu-
rate examinations have convinced me that this part is only an epiphy-
sis of the incus. It is often wanting, even in such ossicula auditus as
appear in other respects to be of the most perfect formation ; for in-
stance, in those of negroes and North American savages, which I
have now before me. When it exists in the adult subject, it can only
be separated by the employment of some force ; and a microscopi-
cal examination of the surfaces shews that the lenticulus has been
broken from the iftcus. Sometimes, indeed, I have found a really
separate ossiculum between the incus and stapes ; but this cannot, in
my opinion, be considered as belonging to the ordinary natural
structure, any more than those other supernumerary ossicula, which
are found not unfrequently both in man and animals." Beschreibung
der Knochen, p. 144,

Cuvier describes a portion of bone as passing between the crura
of the stapes, from one side of the fenestra ovalis to the other, in the
mole and marmot, (in which last animal it is of considerable size).
Lemons d'Anat. comp. p. 489, torn. ii. Mr. Carlisle has represented
this part in the marmot, and he states its existence likewise in the
guinea pig. {Philos. Trans. 1805, pt. 2.)

Cuvier has also found that the stapes is nearly solid in the ceta-
cen ; and that there is no perforation in the walrus. This peculiarity
of structure seems to belong to such mammalia as live in water ; for
the seal has it in a smaller degree. Legons d'Anat. comp. torn. ii. p.

* That the lenticulus, or fourth bone, is only a process of the incus, I have already
shewn in my Geschicte und Besch. der Knochen des Mensch. Kmpers, p. 155.

See Sir A. Carlisle's excellent paper on the physiology of the stapes, in the Phil.
Trans. 1805.

t Home, loco citato,

t Adair, in Cowper's Myotomia refoi-mata. Lond. 1694, 8vo. p. 70, fig. 9.

Teichmeyer, Vindicice quorundam Inventorum /tnatomicorttm, Jenae, 1727-4,
fig. 5.

282 ON THE ORGAN OF HEARING.

o05. Carlisle, loc. citat. gives drawings of the stapes in these ani-
mals.

The second ossiculum of the omithorhynchus approaches very
much in its form to the single bone of birds. (Carlisle, loc. cit.)

§ 261. The part which is termed the labyrinth of the ear,
as far as it has been hitherto investigated in the four-footed
mammalia, seems to agree on the whole, in its essential points,
with that of the human subject. But the cochlea (which be-
longs indeed exclusively to this class) has in some cases a turn
more than in man; not to mention other differences of less
itiaportance.*

,§ 262. In addition to what has been observed respecting
the Eustachian tube of the cetacea, some other parts of the
organ of hearing exhibit such peculiarity in these animals,
and deviate so widely from those of warm-blooded quadrupeds,
that they require particular notice-i'

Their want of external ear is well known. The opening of
the meatus is remarkably small. The bony part of the organ
is loosely connected to the skull in the dolphin and porpoise ;
and it is completely separate in the proper whales {balcence)
and cachalot {physeter).

The hard bony substance, which was formerly very errone-
ously called lapis manati or tiburonis, is merely the tympanum
and bulla ossea of the whale.

The ossicula auditus, and the labyrinth, particularly the
bony canals, {canales semicirculares) which for this very rea-
son were long overlooked, are remarkably small in the ce-
tacea.

* The reader may consult on this subject the following works, besides those which
have been already referred to. Scarpa De Structura Fenestra rotunda) Auris,
Mutin. 1777. 8vo. p. 94. P. F. Meckel De Labyrinthi Auris Contentis. Argent.
1774.

t On the organ of hearing in the true whale, (balcena) see Camper's Kleine
Schriften, vol. ii. pt. 1. In the spermaceti whale, (physeter) ibid. vol. i. pt. 2. In the
dolphin, (delphinus delphis) Klein, Hist. Nat. Piscium, pt. 1, p. 29, tab. 5, fig. 1-4,
and 7-9. In the porpoise, (delphinus phoceena) and dolphin, Monro's Three Treatises,
&c. tab. 5, 6, and his Physiology of Fishes, tab. 35.

ON THE ORGAN OF HEARING.

BIRDS.

§ 263. This whole class,* as well as the following ones, has
no cartilaginous external ear, which belongs, therefore, exclu-
sively to the mammalia. This apparent deficiency is com-
pensated in birds, particularly in those of ttie rapacious kind,
by the regular arrangement of the feathers round the open-
ing of the meatus. Several also, chiefly of the last men-
tioned class, and particularly among the owls, have a peculiar
valve placed at the opening, partly of a membranous, partly
of a muscular structure.i-

§ 264. The membrana tympani of birds is convex on its
outer surface ; and the tympana of the two ears are con-
nected together by the air-cells of the cranium. J

They have a single ossiculum auditus, connecting the mem-
brana tympani with the fenestra ovaHs, and consequently sup-
plying the place of the malleus and stapes of the mammaha.

The part corresponding to the malleus, is generally cartila-
ginous, and not provided with any tensor tympani.

The Eustachian tubes have a kind of common opening on
the arch of the palate.

§ 265. The labyrinth is distinguished by large canals, pro-
jecting from the cranium, and not hollowed out of a hard bony
substance, as in most mammalia, and by the want of cochlea.
Instead of the last-mentioned part, birds have a short, obtuse,
and hollow bony process, passing obliquely backwards from
the vestibulum ; and divided by a partition, like the cochlea of
mammalia, into two scales, one of which terminates at the fe-

• On the organ of hearing in this class, see Allen Moulins, in the Philos. Trans.
vol. xvii. p. 712. Vicq d'Azyr, in the M^m. de I'Acad. des Sciences, 1778, p. 381.
Scarpa De Slructura Fenestra rotundm Auris, p. 101, and De Auditu. Galvani, in
the Commen. Inslit. Bonon. torn. vi. p. 420. Comparetti, tab. 2. Of the preda-
cious birds, the domestic fowl, and the sparrow.

t Klein, Stemmata Avium, tab. 10, fig. 2. Comparetti, tab. 2, fig. 2, he com-
pares this part to the concha of the human ear.

t Sir E. Home has observed the same kind of communication, by the means of
the cells of the cranium, in the elephant.

284 ON THE ORGAN OF HEARING.

nestra rotunda. This part receives a portion of the auditory
nerve as the cochlea does.

AMPHIBIA.

§ 266. The different orders and genera of this class* exhi-
bit greater variety in the structure of the organ of hearing
than the two former, or the following class. Hence the prin-
cipal variations must be separately considered.

§ 267. Turtles, frogs, and most species of the lizard kind,
possess, besides semicircular canals, a tympanum and Eusta-
chian tube, like warm-blooded animals. Both the latter
parts, however, as well as the ossicula auditus, are wanting in
the salamander.

The membrana tympani of the turtle resembles a mass of
cartilage, and is covered externally by the common integu-
ments. Their single ossiculum resembles that of birds.

Frogs have a large membrana tympani exposed to view on
the surface of the body ; a wide opening of their short Eusta-
chian tube at the fauces ; two cartilaginous ossicula ; and a
rudiment in the vestibulum of those soft stony substances,
which are found in a more conspicuous form in the lizards
and serpents, and in the three following classes.

The crocodile is the only instance in which there is a sort
of external meatus in the class amphibia. This animal, as
well as the lizards, possesses ossicula, and the above-men--
tioned stony concretions in the vestibulum.

The want of tympanum in the salamander has been al-
ready mentioned. The foramen ovale in this animal is merely
closed by a portion of cartilage, and the vestibulum contains
a soft stone.

I 268. The serpents, with a very few exceptions, as the

* In the 7th vol. of the Comment. Instit. Bonon. Brunelli has described and de-
lineated the organ of hearing in the turtle, tortoise, frog, lizards, and serpents. Com-
paretti has also exhibited figures of these genera and orders, tab. 2, fig. 13-35 ; and
Scarpa has given most beautiful engravings of the ear in the turtle, crocodile, green
lizard, salamander, viper, and Uind-worm, De Auditv, tab, 5. See also Monro, on
the turtle, in the Fhijsiology of Fishes.

ON THE ORGAN OF HEARING. 285

blind-tvorm,* {a)ignis fragilis) have neither tympanum nor
Eustachian tube. They have a kind of rudiment of ossiculum.

FISHES.

§ 269. It is only in some genera of cartilaginous fishes, viz.
the sJcate and sharh, and lampreys, that a tubular appendix of
the vestibulum is continued backwards and outwards, so as to
represent a rudiment of a tympanum.

§ 270. Much light has lately been thrown on the organ of
hearing in the bony fishes by Professor Weber. f They pos-
sess near the anterior cervical vertebrae considerable ossicvila,
which may be compared to the malleus, incus, and stapes ;
and in those which are provided with a swimming bladder,
these bones are so connected with that organ as to render it
probable that it is auxiliary to the sense of hearing.

§ 271. Their internal ear consists of three large canals,
which are generally seen to project into the cavity of the
cranium.:!: Opposite to the termination of the auditory nerves
on the vestibulum, one, two, or three neatly formed stones
are found. These are as white as porcelain, particularly in
several of the bony fishes, and very dry and brittle in their
texture. §

§ 272. The internal ear of fishes is distinguished from that
of the other three classes of red-blooded animals, by this
remarkable peculiarity, that it grows as the fish increases in
size, and consequently that its magnitude is in the direct
ratio of the bulk and age of the animal.

* Scarpa, loco citato, p. 26.

t Weber, in the work above cited, p. 28.

t See Klein, Mantissa Ichthyologica. Lips. 1746, 4to.

Kölreuter, in the Nov. Comment. Acad. Pelrop. torn. xvii. p. 521. Of the sturgeon
and beluga (acipenser sturin and huso).

Camper's Kleine Schriften, vol. i. pt. 2, tab. 2, of the cod ; vol. ii. pt. 2, tab. \-'i
of the frog-fish, (lophius piscatarius) pike, and skate.

The organ is delineated in several fishes, in the work of Comparelti, tab. 3 ; in
Scarpa, tab. 1, 2, 4; and in Monro's two works. See also J. Hunter's Observaliotn
OH tlte Animal Economy, p. 69.

$ Klein, Hul, Pitcium, pt. 1, tab. 2.

286 ON THE ORGAN OF HEARING.

The membranous canals and vestibulum of the amphibia and
fishes are much smaller than the bony or cartilaginous cavities in
which they reside. Hence these parts can be discerned and demon-
strated much more easily in these animals than in mammalia and
birds, where they are closely surrounded by the bone.

INSECTS.

§ 273. There is no doubt that several insects possess the
sense of hearing ;* but the organ of this sense is very uncer-
tain. In some of the larger animals of the genus cancer, a
part can be distinguished, which seems to be analogous to the
vestibulum of the former classes.'}' A small bony tube is
found on each side at the root of the palpi : its external
opening is closed by a firm membrane ; and it contains a
membranous lining, on which a nerve, arising from a common
branch with that of antennae, is expanded. The latter cir-
cumstance might favour an opinion that the antennae them-
selves are organs of hearing; but this is refuted by considering
the exquisite sense of hearing which some insects possess which
have no true antennae, as the spiders ; and by experiments on
others, which shew that the sense of hearing is not weakened
by removing the antennae.J

VERMES.

§ 274. In the sepice only has any thing been hitherto disco-
vered at all like an organ of hearing. In the cartilaginous
ring, to which the large tentacula of the animal are affixed,
two oval cavities appear. In each of these is a small bag,
containing a bony substance, and receiving the termination of
nerves, like those of the vestibulum in fishes. §

* See the works of Lehmann and Schelver, which I have already often quoted.

t P. A. Minasi, Dissertazione sopra varii fatti meno ovvii della Storia Naturale.
Nap. 1775, 8vo. fig. 4, of the cancer paguriis. Scarpa, De Auditu, tab. 4, fig. 4,
5, 6, of the crawfish. Comparetti, tab, 3, fig. 26, 28, of the several other species.
But whether the parts represented in the other figures of this table, on the heads of
several insects, as beetles, butterflies, common flies, &c. are really organs of hearing,
is extremely doubtful.

J Lehmann De Antennis Insectorum, Dissert, poster, p. 45.

$ Scarpa, loc. cit, tab. 4, fig. 7, 11. Comparetti, tab. 3, fig. 10 and 16.

28\

CHAPTER XXI.

ON THE EYE.

§ 275. A SENSIBILITY* to the impressions of light is common
to all those animals which, in a natural state, are exposed to
this element: it appears at least very evidently to exist in
some of the most simple zoophytes, as the armed polypes
{hydrcs) : but the power of perceiving the images of external
objects is confined to those who are. provided with eyes for
the reception of those images. Nature has bestowed on
some species, even of red-blooded animals, a kind of rudiment
of eyes which have not the power of perceiving light : as if in
compliance with some general model for the bodily structure
of such animals. This is exemplified in the proteus ;-\ in the
blind rat, {marmota typhlus) among mammalia; and in the
myxine glutinosa, among fishes.

§ 276. Since the eye :]: is a very complicated organ, parti-
cularly in the red-blooded animals, we shall first speak of

* Much infonnation on the subject of this chapter is to be found in Rudolphi's
Crundriss der Physiologie, vol. ii. pt. 1. Berlin, 1823.

t G. E,. Treviranus, in the work above cited, s. 319.

t See Bidloo, De Oculis et Visu variorum Animalium. Lugd. Bat, 1715-4.

Zinn De Differentia Fabricce Ocuti Humani et Brutorum, in the Comment. Societ.
lieg. Scient. Catling, torn. iv. 1754, p. 191 ; and in the Comment. Antiqitior. 1778,
p. 47.

W. Porterfield On the Eye. Edinb. 1759, 2 vols. 8vo.

Haller, in the Opera Mi7ioi-a, torn. iii. p. 218.

L. H. T. Schreger's Versuch einer vergleichenden Anatomie des Auges und der
Thriivenorgane. Leipz. 1810.

Schreger's Armcht der Augen durch alle Thierclasten, in the Abhandlung der Fhy-
■<rlk. Medicin. Societ. zu Erlangen.

288 ON THE EYE.

those peculiarities which affect the globe itself, its membranes,
and humours ; and afterwards consider the surrounding parts,
as the eyelids, lacrymal passages, &c.*

Large animals have small eye-balls in proportion to their size:
this is very remarkably the case with the whales. Those which
are much under ground have the globe also very small, as the inole
and shreu} : in the former of these instances its existence has been
altogether denied ; and it is not in fact larger than a pin's head.

The eyes of man and the simice are directed forwards ; in the
latter animals indeed they are placed nearer to each other than in the
human subject. The lemur tarsius has them more closely approxi-
mated than any other animal. All other mammalia have these
organs separated by a considerable interval, and directed laterally.
The same circumstance obtains in birds, with the exception of the
ow/, who looks straight forwards. They are placed laterally in all
reptiles. Their situation varies much in fishes ; they look upwards
in the uranoscopus : they are both on the same side of the body ill
the pleuronectes ; but in general their direction is lateral.

The form of the globe varies according to the medium in which
the organ is to be exerted. In man and the mammalia it deviates
very little from the spherical figure. In fishes it is flattened on its
anterior part ; in birds it is remarkably convex in front, the cornea
being sometimes absolutely hemispherical. The convexity of the
crystalline is in an inverse ratio to that of the cornea. Thus in fishes
it is nearly spherical, and projects through the iris, so as to leave
little or no room for aqueous humour : the cetacea, and those qua-
drupeds and birds which are much under water, have this part of
the same form. The aqueous humour being of the same density with
the medium in which these animals are placed, would have no power
of refracting rays of light which come through that medium : its
place is supplied by an increased sphericity of the lens. In birds
these circumstances are reversed ; they inhabit generally a somewhat
elevated region of the atmosphere ; and the rays which pass through
this thin medium are refracted by the aqueous humour, which exists in
great abundance. Man, and the mammalia which live on the surface
of the earth, hold a middle place between these two extremes.

MAMMALIA.

§ 277. It has been long knownt that the sclerotica in seve-
I'al quadrupeds of this class, as in the human subject, is not

* A. Blumenthal De externis oculoi: integumentis quorundam Animalium. Berol.
1812.

t ZiuR, in the Comment. Soc. Reg. Scient. Gotting. torn. iv. p. 192.

ON THE EYE. 289

throughout of equal strength ; but that its posterior is much
thicker tlian its anterior part. It has also been conjectured,
that this structure might influence what are called the internal
changes of the eye ; by which the form of the eyeball, conse-
quently the length of its axis, and the respective situation of
the lens, are adjusted according to the proximity or remote-
ness of the object, or in reference to any other relations. I
flatter myself that I have ascertained the truth of this conjec-
ture, by discovering the admirable structure of the sclerotica
in warm-blooded quadrupeds, which have not only the power
of seeing at various distances, but also in two media of such
different density, as air and water. In the eye of the Green-
land seal, where I first noticed the fact,* the cornea was thin
and yielding ; the anterior segment of the sclerotica, or that
which is immediately behind the latter membrane, was thick
and firm ; its middle circle thin and flexible ; and lastly the
posterior part very thick, and almost cartilaginous. (Plate.
VI.) The whole eye-ball is surrounded with very strong
muscles, and we can easily understand how their action, varied
according to circumstances, produces the requisite changes ;
how the axis of the eye is shortened, when the animal sees in
air, by bringing the lens nearer to the back of the globe, in
order to obviate the strong refraction which the rays of light
experience in passing from the thin medium of air into the
thicker one of the eyes, and vice versa.

The sclerotica of the cetacea is distinguished by the great
thickness of its posterior part ; when the eye-ball equals an
orange in size, the back of this membrane is an inch thick ;
so that, although the globe be spherical, the space containing

* Comment. Soc. lieg. vol. vii. an 1784. Dr. Albers has discovered the same cir-
cumstances in the eye of the walrus, (trichecus rosmarua) and has refuted those ob-
jections which liave been made to the assigned object of this structure, from the ob-
servation of some slight resemblance to it in the eyes of certain land animals, as the
horse, &c. See the G'ött'mg. gslerhle Anzeigen der physical. Me<iicin. S.tciet, zu
Erlangen. 1803, p. 601.

And especially Sömmering, De nculor. Hominis Ariimnliuinqup. sectione horizontali
cammentiitw. Giittinj;. 1818.

U

290 ON THE EYE.

the vitreous humour is of a different form. As the sclerotica
approaches to the cornea, it becomes thinner. Its posterior
part presents a very singular structure, consisting of very
firm tendinous threads and laminae, most closely interwoven,
and of more than cartilaginous hardness* towards the sides.

The extent of the cornea, when compared to that of the
sclerotica, varies in the different species of mammalia. It
seems to be greatest in the porcupine, {hystrix cristatd) where
the cornea extends over half the globe.

§ 278. The choroid coat consists more plainly in the cetet^
cea than in any other mammalia, of two distinct laminae, of
which the internal {membrana Ruyschiand) is covered with a
dull tapetum.

§ 279. The inner surface of the choroid coat possesses,
towards the back of the eye, in several genera of this class,
particularly in those carnivorous animals which prey by night,
and even in the bisulca, the most brilliant yellow-green and
sapphire-blue colours, forming what is called the tapetum lu-
cidum.'f The coloured portion of the choroid is only partial,
and the rest of the membrane is covered with pigmentum
nigrum, as usual.

In consequence of this structure less light will be absorbed;
and it must, on the contrary, be reflected from the tapetum
against the retina, which lies in front of the membrane.

It is well known that the pigmentum nigrum is entirely, or
for the greatest part, deficient in the eye of the albinos, which
strange variety occurs not unfrequently in the human race,

* Ruysch, Thesaur. Anatom, ii. tab. 1, fig. 1, 2, 6.

Loder, Tabula AriatomiccB, vol. i. tab. 56, fig. 8.

Albers, in the 1st vol. of the Abhandlung der physik, medicinisch. Societ. zu Erlan-
gen, tab. 6.

On the eye of the whale in general, see Albini, Index Supellectilis, J. J. Ravii,
p. 36 ; also his Annot. Acad. lib. vii. p. 40 ; and Supellex Anatomica, p. 132.

Miisei Gaubiani Pars complectens preparata Anatomica, p. 14.

t Zinn, loco citato, p. 196.

H. F. Elsaesser, De Pigmento Oculi nigro, deque Tapeto. Tubing. 1800, 8vo.

L. Gmelin, Indagatio Pigmenti nign Oculm-um Taurinorum. Götting. 1812.

Moüdini, in the Opuscoli scientifici di Bologna, torn, ii p. 15.

ON THE EYE, 291

and in several other mammalia and birds. I know, however,
no instance of an albino among cold-blooded animals. This
anomalous deficiency is always congenital, and is connected
with a want of the colouring principle of the skin, and of the
hair and feathers. It is hereditary in some mammalia, so as
to form a constant breed of white animals, viz. in the rabbity
mouse, and horse, (which latter are those called glass-eyed). \
cannot believe that any whole species of warm-blooded ani-
mals should originally want this pigment, and therefore I
consider the ferret {mu stela furo) to have descended from the
polecat {m. putorius).*

The tapetum occupies the temporal side of the bottom of the eye-
ball ; i. e. it is placed exteriorly to the entrance of the optic nerve.
It exists in the carnivorous and ruminating animals ; in the solipeda^
pachydermata, and cetacea. In the do^, walf^ and badger, it is of
a pure white, bordered by blue.

§ 280. The retinal exhibits in some quadrupeds, viz. the
hare and rabbit, very distinct and elegant fibres or striae of
medullary substance, taking for the most part a transverse
direction.;}: The remarkable foramen centrale, which Söm-
mering discovered in the human retina, has been since de-
monstrated in the eyes of several quadrumana, where these
organs are dii'ected forwards, and have their axes parallel.

I have found it, for instance, very plain in the eye of the
common Barbary ape (simia sylvanus). The entrance of the
optic nerve formed a small yellow circle on the retina : near
this a larger grey fold appeared, with the foramen centrale in
its middle.

* I have treated at greater length on the want of this pigment, which is so essen-
tial a part in the natural structure of the eye, in the Comment. Soc. Beg.Scient. vol.
vii. p. 29 ; and in the third edition of my work. De Generis Humaiii Vurietate Nativa,
p. 272.

t For many observations on the retina, especially in animals of this country,
(Germany) see Wantzel, in Isenfiamm's and Rosenmiiller's Beilragen, vol. i. p.
157.

t Zinn, locn cil(it.td.h.S, fig. 3. Fontana .Swr le Venin de la Vipcie, vol. ii, tab,
[>, fig. 12.

u 2

ON THE EYE.

In demonstrating this opening in the eye of a simia cyno-
molgus, I advanced the following conjecture as to its use.
Man, and such animals as have the two eyes placed with their
axes parallel, thereby gain the advantage of seeing objects
with both eyes at once, and therefore more acutely. But at
the same time they are exposed to this inconvenience, that in a
strong light both eyes become dazzled at once ; and this hap-
pens so much the sooner, because the light falls on the corre-
sponding principal focuses of both eyes at once ; the organ
not possessing a membrana nictitans. This inconvenience
seems to be obviated by i\\e foramen centrale : since that part
which forms the principal focus of the eye opens in a dazzling
light, so as to form a kind of small pupil, through which the
concentrated rays pass, and fall on the choroid, where they
are absorbed by the black pigment.

§ 281. The iris, an organ of very peculiar structure, exhi-
bits in the different genera and species of mammalia more nu-
merous and interesting varieties than any other part of the eye.
The colours of its anterior surface, which are peculiar to the
different genera, vary in the races and varieties of domestic
animals, although less strikingly than in the human subject.
These variations are connected, as in the latter instance, with
the colour of the hair ; so that in spotted dogs, rabbits, &c. a
mixture of colours will be seen in the iris.

The substance of the part varies in thickness in the differ-
ent genera. In no instance have I hitherto been able to dis-
cover true muscular fibres ; the examination of the part in the
elephant and whale having afforded in this respect the same
result, as the tender and almost transparent iris of the white
rabbit.

In the eye of the seal the ciliary vessels are npt distributed
in the substance of the iris ; but lie on its anterior surface, and
form a considerable plexus, which is visible without any injec-
tion.*

* Comment. Soc, Reg. Scient, Göetting. loco citato, fig. 2, 3.

ON THE EYE. 293

The pupil in the bisulca, solidungula, ceiacea, &c. is trans-
verse ; in animals of the cat kind, particularly in a clear light,
it is oblong : not to mention other trivial peculiarities, as the
small villous appendix, covered with pigmentum nigrum, which
is sometimes seen on the middle of the superior margin of the
pupil, particularly in the Jiorse. The pigmentum nigrum has
a brown colour, in the eye of a white horse which is in my
collection ; while the other parts of the same eye, which in
horses in general are black, have only a slight greyish brown
tinge. Swammerdam, in speaking of the remarkable curtain
of the pupil, which is found in the skate, says he has discover-
ed a similar part in the Jiorse. If he does not allude to any
unusual formation, but merely to such appendices as I have
mentioned, tlie comparison is certainly too far fetched.*

The figure of the pupil is transversely oblong in the ruminating
animals and the horse ; it is heart-shaped in the dolphin.

§ 282. The corpus cihare, and particularly the folds of its
internal surface, with their numerous and elegantly arranged
blood-vessels, constitutes one of the most wonderful parts of
the eye, although its functions, which must undoubtedly be of,
the highest importance, are hitherto involved in mystery. Its
more minute differences in the genera, which have been hi-
therto examined, are too numerous to be recounted ; and they
could not be understood without delineations.t Among other
instances, those of the elefhant and liorse may be mentioned,
on account of the remarkable beauty and delicacy of their
structure.

§ 9,^^. The size of the crystalline lens varies in proportion
to that of the vitreous humour ; and sometimes very consider-
ably. I have found the largest lens in this point of view in
the comparatively small eye of the opossum (ßideliJhis marsu-

* Biblia NaiurcE, p. 881.

t Much information may be gained on this subject from Jac. Hovius De Circulari
Humorum Molu in OcuUs, ed. 2. Lugd. Bat. 1716, 8vo. 'lliis work, however,
is in some parts unintelligible, and not to be depended on ; and must, therefore, be
consulted with caution.

^94

ON THE EYE.

pialis) ; the whale has the smallest. No mammalia have it so
slightly convex on the surface as the adult man. In the cat,
hare, the bisulca, the horse, opossum, and seal, it becomes
more and more convex according to the series in which I have
named these animals. Lastly, in the cetacea it is nearly sphe-
rical.*

The crystalline is smaller in the eye of man than in any animal, and
it is largest in the fishes.

The following numbers give the proportions of the three humours,
measured on the axis of the eye, after it had been frozen.

Aqueous Humour, Crystalline.

Vitreous Humour

Man . .

^V

• . A .

u

Dog . .

Ä

. . A •

A

Cow . .

-h •

. i^ .

¥r

Sheep . .

tV <

1 1

TT *

n

Horse . .

Ä •

I6

-47 '

u ■

Owl , .

^r '

I I

^v

Herring .

I
r

• f •

T

The greater convexity, which the author ascribes to the seal and
whales, arises from their inhabiting the water ; so that they require
an organ of vision like that of fishes-
It is curious to observe the regularity with which, in some
species, the lens divides into certain segments commencing
from its centre, in consequence of being dried or immersed in
acids-i*

§ 284. A lacrymal gland% exists in all animals of this class.
Several quadrupeds have, indeed, an additional one, besides
that which is found in the human subject. Some have no

* F. P. Du Petit, in the M£m. de I'Acad. des Sciences, 1730. The memoir is
translated in Froriep's Bibliothek ßk- die vergleichende Anatomie, vol. i, p. 200.
t Leuwenhoeck, Arcana Natura detecta, p. 73.
Perrault, Histoire des Animaux, pt. 1, tab. 30.
Young, in the Fhilos. Trans. 1793, tab. 20.
Hosack, Fhilos. Trans. 1794, tab. 17.

J. C. Rail, De Lentis CrystallwiKe Structura Fibrosa. Halle, 1794, 8vo.
J Bertin, in the M£m., de I' Acad, des Sciences, 1766, p. 281.

ON THE EYE. 295

puncta lacrymalia ; and the elephant has neither lacrymal
bag nor os unguis.*

In addition to the lacrymal gland, several mammalia have another
body, called the glandula Harderi. This is situated nearer to the nose,
and pours out a thick whitish fluid near the third eyelid. It joins
the proper lacrymal gland in the hare and rabbit ; but is distinguished
by its whiter colour. The ruminantia, Carnivora, and pachydermata,
have it likewise.

The ducts of the lacrymal gland admit of very easy demonstration
in the larger quadrupeds, where they open to the number of sixteen
or more, by orifices that will admit a large bristle.

The hare and rabbit have, instead of puncta lacrymalia, a slit open-
ing into the lacrymal canal.

The cetacea want the lacrymal apparatus entirely, as their eyes are
preserved in a moist state by the element in which they live.

The muscles of the eye-ball are the same in number in the simice as
in man : but other mammalia possess an additional one, termed the
suspensorius oculi.

This muscle is of a conical form. Its origin, which takes place
from the margin of the optic foramen, represents the apex of the
cone ; and its insertion into the posterior half of the sclerotica, con-
stitutes the basis. It fills up therefore the interval left between the four
recti, and surrounds completely the optic nerve. In several of the
Carnivora and the celacea it is divided into four portions ; so that
these animals may be said to have eight straight muscles. It must
enable the animals which possess it to draw the globe back into the
orbit ; and hence it has sometimes been called the retractor of the
eye.

A remarkable peculiarity occurs in the conjunctiva of the zemni,
[tntis typlilus). It is covered with hair as in other parts of the body,
so that the eye, which is indeed exceedingly small, seems to be com-
pletely useless. A similar structure is also found in two fishes, the
murena Cecilia and myxine glutinosa {gastrobranchus c£ecits, Cuvier).
Legons d'Anat. comp. torn. ii. p. 394.

§285. The nictitating membrane, {memhr ana nictitans, pal-
pebral tertia, seu interna, periopJdhalmiutn) of which only a
rudiment exists in the quadrumana and the human subject, is
very large and moveable in some quadrupeds. -f- This is the
case in animals of the cat kind, in the opossum, the seal, and
particularly in the elephant.

* Camper, CEuvres, torn. ii. p. 138, where he also states that this animal has no
lacrymal gland, nor passage for the tears into the nose,
f Tabarrani, in the Auidi Siena, torn. iii. p. 115.

^96 ON THE EYE.

§ 286. The relative magnitude of the true eyelids varies
considerably in animals of this class. The lower, which is very
large in the elephant, is very small in the horse. In the latter
animal, as well as in most quadrupeds, it has no cilia ; while in
the quadrumana, the elephant, the giraffe, and others, both
eyelids possess eyelashes.

BIRDS.'

§ 287. The eyes are very large in this class of animals,* and
consequently the bony orbits are of great magnitude in pro-
portion to the skull.

In the birds of prey they have a peculiar form, which is simi-
lar to that of the chalice, or cup used in the communion service :
the cornea, which is very convex, forms the bottom of the
cup ; and the posterior segment of the sclerotica resembles its
cover .i-

§ 288. This peculiar form arises from the curvature and
length of the bony plates, which, as in all other birds,:]: occupy
the front of the sclerotica ; lying close together, and overlap-
ping each other. These bony plates form in general a flat, or
slightly convex ring ; being long and curved in the accipitres,
they form a concave ring, which gives the whole eyeball the
above-mentioned form. Dr. Albers observes that the orbit is
very imperfect in birds ; and that this bony ring may supply
the deficiency.

§ 289. The distinction between certain parts of the eye,
where the membranes have been supposed to be continuous,
appears more plainly in some birds, than in any other animals.

* Besides the works which have been referred to above, see the memoirs of
Petit on this subject in the Mem. de I' Acad, des Sciences, an 1726, 1735, and 1736,
Home in the Philos. Trans. 1796.
Albers, Beytriige, vol. i. p. 69.

Sömmering, in the Denkschriften der Akad. zu München, 1811, p. 177.
f Severini, Zootomia Democritea, p, 336.

Em. König, in the Ephem, Natur. Curios. Dec. II. an 4, Obs. 34.
:|: Goiter, Miscell. Observ. Anat. Chirurg, p. 130.
Pierce Smith, in the Fhilos. Trans. 1795, pt. 2, p. 263,

ON THE EYE. ^97

Thus I have found the boundaries of the choroid coat and iris
very clearly defined in the horned owl (strix bubo) ; and those
of the margin of the retina, and the posterior border of the
ciliary body very distinct in the toucan {ramphastos tuca-
nus).

The ciliary processes of birds are not very prominent ; they con-
sist rather of striae than of loose folds. They are always closely
connected to the crystalline capsule. There is no tapetum in this
class.

The colour of the iris varies in the different species of birds ; and
in many instances possesses great brilliancy. It has a power of vo-
luntary motion in the parrot.

The retina passes obliquely through the sclerotica, in a sheath of the"
latter membrane.

§ 290. A great peculiarity in the eye of birds consists in the
marsupium* {pecten plicatum ; in French, la bourse, le peigne)
the use of which has not hitherto been very clearly ascertained.
It arises in the back of the eye, proceeding apparently through
a slit in the retina ; it passes obliquely into the vitreous humour,
and terminates in that part, reaching in some species to the
capsule of the lens. The figure of its circumference is a trun-
cated quadrangle. Numerous blood-vessels run in the folds of
membrane which compose it ; and the black pigment by which
it is covered, suggests an idea that it is chiefly destined for the
absorption of the rays of light, when they are too strong or
dazzling. Others believe that it serves in this class for the in-
ternal changes of the eye ; but Crampton has contested this
opinion, and described a peculiar circular muscle in the eye-
ball of the ostrich, and several large birds, by which these
changes are efiected.f

% 291. Birds have large lacrymal passages which terminate
on the surface of the palate.J

* See a neat delineation of the internal parts of the eye in the osprey, {falco ossi-
fragus) by L), G. Kieser, De Aiiamorphoü Oculi. Goetting. 1804, 4to. tab. 2, fig, 1.
The whole dissertation contains much instructive matter on this subject.

See also J. A. Hcgar De oculi ■partlbus quibusdam. Gotting. 1818.

f In Dr. Thomson's Annals of Pldlosophy for March, 1813.

X Monro, Observations Anatomical and Physioln^ical. Edinb. 1758, 8vo,

Albcrs, loco citato, fig. 1, 2.

398 ON THE EYE.

Their nictitating membrane"* is furnished with two very ma-
nifest muscles.f

In some species, as the common fowl, the turkey, goose, and
duck, the lower eyeUd, which contains a peculiar small lamina
of cartilage, is the most moveable ; in others on the contrary,
as in the parrot and ostrich, the upper has the most extensive
motion.

Very few birds have cilia in both eyelids ; they are found
in the ostrich, the falco serpentarius, the razor-billed blackbird,
{crotophaga am) and in some parrots.

Birds possess both a lacrymal gland and glandula Harderi. The
latter is considerably the largest ; and is usually placed between the
elevator and adductor muscles of the globe. It furnishes a thick yel-
low fluid, which is poured from a single duct, opening on the inner
surface of the third eyelid.

The eyelids are closed in most birds by the elevation of the infe-
rior palpebra, which is the largest. This eyelid has a peculiar de-
pressor muscle arising from the bottom of the orbit. The owl, and
the goatsucker are among the few in which the upper eyelid de-
scends.

The third eyelid, or memhrana nictitans, is a thin, semi-transpa-
rent fold of the conjunctiva ; which, in the state of rest, lies in the in-
ner corner of the eye, with its loose edge nearly vertical, but can be
drawn out so as to cover the whole front of the globe. By this, ac-
cording to Cuvier, the eagle is enabled to look at the sun.

It is capable of being expanded over the globe of the eye by the
combined action of two very singular muscles, which are attached
towards the back of the sclerotica. One of these, which is called
from its shape the quadratus, arises from the upper and back part of
the sclerotica ; its fibres descend in a parallel course towards the optic
nerve, and terminate in a semicircular margin, formed by a tendon of
a very singular construction ; for it has no insertion, but constitutes a
cylindrical canal. The second muscle, which is called the pyramidalis,
crises from the lower and back part of the sclerotica towards the
nose. It gives rise to a long tendinous chord, which runs through
the canal of the quadratus, as in a pulley. Having thus arrived at
the exterior part of the eyeball, it runs in a cellular sheath of the
sclerotica along the under part of the eye, to the lower portion of the
loose edge of the memhrana nictitans, in which it is inserted.

By the united action of these two muscles, the third eyelid will be
drawn towards the outer angle of the eye, so as to cover the front of

* It is called by the Emperor Frederic II. pellicula palpebrarum,
t Petit, in the M^m. de I' Acad, des Sciences, 1735 and 1736.

ON THE EYE. 299

the globe ; and its own elasticity will restore it to its former situa-
tion.

AMPHIBIA.

§ 29S. Little is hitherto known concerning the peculiarities
in the structure of the eye of this class.*

In some reptiles and serpents of this country, (Germany) the
common integuments form, instead of eyelids, a kind of firm
window, behind which the eyeball has a free motion.

In the green turtle-f- {testudo mydai) the sclerotica has a bony
ring at its anterior part, composed like that of birds, of thin
osseous plates. These animals possess very large lacrymal
glands, and a very moveable membrana nictitans ; in which
circumstance the frog resembles them.J

The ciliary processes are hardly perceptible in the turtle ; but they
leave an elegant impression on the surface of the vitreous humour.
They are distinct and long in the crocodile. The blood-vessels are
visible on the surface of the iris ; where they form a distinct plexus in
the crocodile.

The optic nerve forms a tubercle within the sclerotica ; from which
the retina commences.

The number, &c. of the eyelids varies considerably in this class.
Serpents have none. The turtle and crocodile have three like those
of birds. The frog and toad have three ; of which the third is much
the largest and most moveable.

The turtle has a very large lobulated lacrymal gland. Serpents
have nothing of this kind.

FISHES.

§ 293. The peculiarities in the eye of fishes,§ which belong

* Petit, in the Mem. de I'Acad. des Sciences, 1737, p. 142.

t Albers, in the Denkschriften der Akad. zu München, 1 808-

j: Caldesi Osservazioni suUe Testtidini, tab, 8, fig. 11.

§ Good delineations of the internal structure of the eye of fishes are still wanting.
The best which I know of are by Guenellon, of the corf's eye; but they are con-
tained in a book where one should not much expect to find them, viz. in Bayle's
Nouvelles de la Itepuhlique des Lettres, March, 1686, p. 326. See also Albers, in
the work above cited ; and Rosenthal, in the 10th vol. of the Archives für Physioln-
gie.

300 ON THE EYE/

either to the whole class, or to most of the genera and species,
consist in the division of their choroid coat and retina into se-
veral manifestly distinct laminae ; and in the existence of two
small organs within the eye, which belong exclusively to this
class.

§ 294. The choroid coat, which in man is a simple mem-
brane, and in some other warm-blooded animals, particularly
in the cetacea, a double one, consists in fishes of three distinct
laminaB. The inner layer forms a tunica Ruyschiana ; the
middle one {membrana vasculosa of Haller) is perfectly dis-
tinct both from the former and from the exterior coat ; which
latter must be compared with the proper choroid of all red-
blooded animals. Even this last is continued anteriorly into
the iris, and possesses in many species the well known brilliant
gold and silver colours.

The retina is easily separable into two laminae; of which
the external is medullary, and the internal consists of a fibrous
texture.

§ 295. The two other peculiarities belong exclusively to the
eye of fishes ; and are common at least to the whole bony di-
vision of these animals. A body, generally resembling in
shape a horse-shoe, lies between the internal and middle lay-
ers of the choroid ; some have thought it muscular, and others
glandular. The tunica Ruyschiana gives origin to a vascular
membrane, resembling in its form a bell {campanula of Haller).
This goes towards the lens, and has, therefore, some resem-
blance to the marsupium of birds.

No true ciliary body is found, at least in the bony fishes.

§ 296. The crystalline lens of most fishes is very large in
comparison with the size of the eyeball, and nearly or entirely
spherical. The vitreous humour on the contrary is small, and
the aqueous in many cases is hardly discernible.

§ 297. The following may be enumerated as instances of
remarkable peculiarities in the eyes of particular genera and
species of fishes. The firm transparent laminse of common in-
teguments, behind which the eyeballs move, as in some am-

ON THE EYE.

301

phibia ;* the articulation of the globe on a stalk of ca^^tilage in
the skate and shark :f the curtain {operculum pupiUare)\n the
eye of the skate, J which can be let down so as to cover the pu-
pil : and the unique structure of the lobitis anableps, where
the cornea is divided into two portions, and there is a double
pupil with a single lens.§

The continuation of the conjunctiva 'over the cornea admits of being
demonstrated in the eel. For it comes off sometimes with the rest
of the skin of the head in stripping off the integuments of this ani-
mal.

The organ of vision exists only in one class of animals, without
exception, viz. in birds. In mammalia there are two instances of
complete blindness, one in the blind mouse (spalax typlilus, Pall. Mus
typhlus, L.) and the other in the golden mole (chrysochlonis, sorex au-
reus). Among amphibia the proteus anguimis has small eyes covered
over with a transparent membrane, through which it has merely the
powers of perceiving light, without being able accurately to distin-
guish objects. Among fishes the hag-fish {gastrohranchus ccecus myx-
ine glutinosa, Linn.) is said to have no trace of the organ of vision,
and in the Mind murena no traces of the eye can be seen externally,
but beneath the skin rudiments of this organ may be detected.
Among insects there are several species of beetles which live in the
nests of ants, and are nourished by them, that have no eyes ; further
there is a species braula, very nearly allied to the dipterous insect,
and which live parasitically on bees, in which no eyes have been de-
tected. There are also some species oi ants, as ihe formica contracta
and formica cceca, in which the organ of vision is wanting. In Lin-
naeus's class vermes, the cephalopoda are provided with eyes ; the ex-
istence of the organ of vision is also ascribed to the gasteropoda,
which Rudolph], however, is disposed to doubt. In snails the eyes
are placed at the extremities of the tentacula. In the remaining
mollusca the eyes are certainly wanting.

* Abbildungen natur-historisch. Gegenstände, pt, 6, where the part is represented in
the ostracion bicuspis.

t Stenonis Specimen Elementar. Myologia', tab. 5, fig. 1.

Goyeau, in the Mercure de France, Dec. 1757, p. 130.

Perrault, Essais de Physique, torn. iii. tab. 1, fig. 4.

Radkin, in Abel's Journey in the Interior of China, p. 338.

X Stenonis De Musculis et GlanduUs, p. 68. Camper, in the Mämoires präsente» ä
I'Acad. des Sciences de Paris, torn. vi. tab. 3, fig. 1.

$ Seba Thesaur. Rer. Natural, torn. iii. tab. 34.

Camper, in the German translation of Monro's Physiol, of Fishes, p. 165.

Lacepede, in the Mt^m. de /'Institut. National, tom. ii. p. 372.

.Sdineider, in the 4th vol. of the Keue Schriften der Natnrf, Gesclls. tu Berlin.

302 ON THE EYE.

The muscles of the membrana nictitans were supposed to exist only
in the elephant among mammalia, but Rudolphi has discovered them
in the hycena, and Albers has seen them in the seal. These parts
have been described in several mammalia by Rosenthal in his Diss,
de externis Oculorwn tegumeniis. Berol. 1812.

In animals which have a third eye-lid, there is a peculiar gland,
which has been incorrectly stated to exist in the human subject. The
matter which it secretes is of a yellowish white colour, and thick con-
sistence.

All mammalia, and even fishes, possess the four straight and two
oblique muscles of the eye. In the tortoise and crocodile there are, in
addition to these six muscles, small posterior straight ones. In frogs
and toads there are three additional recti. Birds have only the six usual
muscles. Man and the apes have only six, but the rest of the mam-
malia have, in addition to the anterior, four posterior straight muscles,
or the retractor muscle, as it is called, which in the predacious and
cetaceous animals, divides into four portions. Where these posterior
muscles exist, the eye can be drawn back with great force. In birds
and amphibia the muscles of the eye, and consequently its motions,
are very weak. In the ray and shark the motions of the eye are much
increased by this organ resting on a thin cartilaginous pulley which
is attached to the bottom of the orbit. In the other fishes the mobility
of the eye is slight, and the motions confined.

The form of the eye frequently varies in different animals. If the
axis of the eyes of animals of different sizes were compared with
their diameter, they will be sometimes found equal. This is the case
according to Sömmering, in the lijnx, the racoon, ostrich, falco
chrysäetos, strix bubo, and the coluber cesculapii ; and, according to
Treviranus, in the fox, badger, hedgehog, and the falco huleo. In man
the axis is somewhat longer than the diameter, according to Sömmer-
ing, as 1 : 0,95. In the simia inuus, as 1 : 0,99 ; in the bat this pro-
portion is the most striking, viz. as 1 : 0,91. In all the other animals
of which Sömmering and Treviranus took the measurements, the dia-
meter has been found larger than the axis. In the ivhale it is by far the
largest. The proportion of the axis to the diameter in the eye of the
balcena jnysticetus is, according to Sömmering, as 1 : 1,43 ; according
to Treviranus, as 1 : 1,54. In order to obtain any thing like an aver-
age, a great number of measurements must be taken of eyes as fresh
as they can be obtained.

Attention should be paid to the proportion of the cornea to the
sclerotica, as on this the form of the eye very much depends. In ce-
taceous animals and fishes the cornea is quite flat, on the contrary it
is very convex in night birds of prey.

In mammalia the cornea is connected, with very few exceptions, in
the same way as in the human subject. There are, however, some
modifications. The sclerotic is of different degrees of thickness
in different parts ; its anterior and posterior portions are thick in
the ox and horse, and particularly the seal, whilst the central one

ON THE EYE. 303

is thin. In the cetaceous animals the sclerotic increases in thickness
from before to behind ; in the whale it is sometimes more than an
inch in thickness. Also in birds the sclerotic becomes thicker at its
posterior portion.

The iris, which presents great varieties of colour in the mammalia,
and which is for the most part dark coloured in wild animals, is re-
markable in birds for the diversity and beauty of its hues. In theßw-
phibia, and still more in fishes, it has a shining metallic hue, resembling
silver or gold. Rudolphi has not besn able to detect muscular fibres
in the irides of any animals.

The pupil is round in the quadrumana, and in some carnivorous
animals ; in the hycena and the cat genus, it is perpendicular ; in the
rurninantia, solidungula, muUungula, and cetacea, it is horizontally si-
tuated. In the horse genus, and several of the rurninantia, the iris is
furnished on both edges, or at least on the inferior one, with small
round processes strongly tinged with pigment. In birds the pupil,
without exception, appears to be round ; and also in tortoises and li-
zards, as the lacerta viridis, agilis, &c. In crocodiles and serpents, it is
vertical. The pupil of fishes is round; and in the raj/ it is provided
with a peculiar process coming from its upper edge, by which it is
capable of being closed.

The ciliary processes are developed in mamfnalia, birds, and some
of the amphibia. Cuvier has not been able to detect them in the com-
mon lizards, or in serpents. They exist also in the shark, and though
Cuvier denies their existence in all bony fishes, they are very visible
in the tnnny, and Treviranus has observed them in the sturgeon and
the salmon. In the cephalopoda they are deeply imbedded in a kind
of sulcus in the lens.

The three humours of the eye exist, without exception, in all the
vertebrated animals ; the aqueous humour exists in a very minute
quantity in fishes, while it is most abundant in birds. The crystalline
lens is spherical in fishes, and approximates more or less to this
form in all aquatic animals, as the crocodile, the cetacea, the seal,
water-rat, and in aquatic birds. The few serpents which go into
the water, as the coluber natrix, have also a spherical lens. In the
chameleon the lens approximates to a spherical form ; in land birds,
on the contrary, it is flat. The vitreous humour is, according to
Tiedemann, of very slight consistence in birds ; but to this remark
there are many exceptions. It exists in small quantity in all ani-
mals ; fishes, however, possess most of it.

INSECTS.

§ 298. Two kinds of eyes, very dissimilar in their structure,
are found in this class.* One sort is small and simple {stemmatd) ;

M. deSerres Sur les Yem comjxms et lea y'eu.t lisses des Insectes. Montpell. 18)3

304 ON THE EYE.

the others, which are large, seem to consist of an aggregation
of smaller eyes ;* for their general convexity is divided into an
immense number of small hexagonal convex surfaces, which
may be considered as so many distinct corneae. The first kind
is formed in diiFerent numbers in most of the aptera, as also in
the larvae of many winged insects. When these vindergo the
last or complete metamorphosis, and receive their wings, they
gain at the same time the large compound eyes. Several ge-
nera of winged insects, and apteia (as the largest species of
monoculii) have stemmata besides their compound eyes.

§ 299. The internal structure has hitherto been investigated
only in the large polyedrous eyes.:!: The back of the cornea
(which is the part, divided in front into the hexagonal surfaces,
called in F.rench, faceites) is covered with a dark pigment. Be-
hind this are numerous white bodies, of a hexagonal prismatic
shape, and equal in number to that of the facettes of the cor-
nea. A second coloured membrane covers these, and appears
to receive the expansion of the optic nerve.

§ 300. Further investigation is, however, required in order
to shew how these eyes enable the insect to see ; and to de-
termine the distinctions between two such very different or-
gans.

I have given, on a former occasion, the reasons which led
me to think it probable, in opposition to the general opinion
formerly maintained ; that the polyedrous eyes are adapted
for^distant objects, and the simple ones for such as are more
near. This is confirmed by observing, that butterflies, which
in their perfect or winged state, have the large compound eyes,
have only the myopic organs while larvse.

* Hooke's Micrographia Restaurata, tab. 20, 21.

t Andre, in the Philos. Trans, vol. Ixxii. part 2, of the Monoculus Polyphemus.

M. de Serres, in the Journal de Physique, 1809.

X Swammerdam, tab. 20, has represented the structure of the eye in the drone or
male bee.

C!uvier, in the Mem. de ia Soci^te d'Hkt. Nat. de Paris, an 7, p. 41, fig. 3, that
of the dragon-ßy, (libellula grandis).

ON THE EYE. 305

Yet there are still some doubts respecting the uses of these
two kind of eyes ; for some complete animalia subterranea, as
the grylhis gryllotalpa, have both kinds.

VERMES.

§ 301. The cultle-fisli only, of this whole class,* has been
hitherto shewn to possess true eyes ; the nature of which can-
not be disputed. They resemble on the whole those of red-
blooded animals, particularly fishes ; they are at least incom-
parably more like them than the eyes of any known insects ;
yet they are distinguished by several extraordinary peculiari-
ties.f The front of the eye-ball is covered with loose mem-
branes instead of a cornea ; the iris is composed of a firm sub-
stance, which seems like a continuation of the sclerotica ; and
a process projects from the upper margin of the pupil, which
gives that membrane a semilunar form.

The corpus ciliare is very completely formed.

In all other vermes the eyes are entirely wanting, or their
existence is very doubtful. Whether the black points, at the
extremities of what are called the horns of the common snail, J
are organs which really possess the power of vision, is still
problematical. §

* Carus Lehrbuch der Zootomie, p. 67, tab. 4, fig. 2, 9.

t Swammerdam, tab. 52, fig. 2.

t Ibid. tab. 4, fig. 7, 8.

j Äleckel's Archiv, vol. v. p. 206.

J. Lauchs, in his Naturgeschicte der Ackerschneche, Neuemb. 1820, p. 20.

306

CHAPTER XXII.

ON THE MUSCLES.

I 302. The heart and other muscular viscera have been al-
ready treated of. We have only to speak here of the proper
musclesj which are destined to the performance of the volun-
tary motions. As the details of myology do not come within
the plan of this work, the present chapter will include only a
few remarks on the peculiarities in the muscular structure of
the different classes, and of some particularly remarkable spe-
cies.*

MAMMALIA.

§ 303* The degree of resemblance between the muscles of
the mammaliaf and those of the human subject^ may be infer-

* It can be hardly necessary for me to state, that the first vol. of Cuvier's excellent
■work contains by far the most complete account that we hitherto possess of compa-
rative myology in general : numerous remarks on the subject may be found also in
Borelli De Motu Animalium; and in Barthez, Nouvelle Mechanique des Mouvemens de
V Homme et des Animauxi Carcassone, 1798, 4to.

Many striking points in the myology of man, and some of the higher animals, are
admirably explained and illustrated in a treatise, entitled ' Animal Mechanics,'
which has been recently published by the Society for the Diffusion of Useful Know-
ledge, and which is understood to be the production of Mr. Charles Bell.

t We have excellent accounts of the myology of particular species of this class :
as for instance, of the chimpansS, (simia troglodytes) by Tyson ; of the dog, by
Douglas, in his Specimen Myographies comparatce ; and by Garengeot, in the Myoto-
mie Humaine et Canine. Paris, 1724, 8vo. ; of the horse, by Stubbs, in his excel-
lent Anatomy of the Horse. Lond. 1766 ; and Alton's Naturgeschicte des Pferdes.
Weim. 1816 ; of the cow, by Vitet, M6decine V6t6rinaire, vol. i.

% On the muscles of the face in man, as they serve to express the different pas-
sions, see C. Bell, On the Anaiomy of Expression in Painting, p. 94.

See

ON THE MUSCLES. 307

red, in any particular instance, by comparing the skeleton of
the animal with that of man. The similarity is greatest/on the
whole, in the quadrumana.* Yet these are distinguished by
the smallness of their buttock and calf of the leg ; the strength
and convexity of which parts constitute peculiar beauties in
the human form.+

The differences which we discern in the muscles of the lower ex-
tremity between man and the other mammalia, arise out ofthat charac-
teristic feature, which so strikingly distinguishes man from all othier
animals, viz. his erect stature. An accurate examination of this sub-
ject will shew us that the erect position belongs to man only ; and
that the well known passage of the Roman poet is not merely distin-
guished by the elegance of its diction, but confirmed by the results of
physiological investigation.

Pronaque cum spectent aniraalia cetera terram,
Os homini sublime dedit ; cceluraque tueri
Jussit ; et erectos ad sidera tollere vultus.

In order to enable any animal to preserve the erect position, the
following conditions are required: 1st, that the parts of the body
should be so disposed as to admit of being maintained with ease in a
state of equilibrium ; 2ndly, that the muscles should have sufficient
power to correct the deviations from this state ; 3rdly, that the centre
of gravity of the whole body should fall within the space occupied by
the feet ; and lastly, that the feet themselves should have a broad
surface, resting firmly on the ground, and should admit of being in a
manner fixed to the earth. All these circumstances are united in the
necessary degree in man only.

The broader the* surface included by the feet, the more securely
will the line of gravity rest within that surface. The feet of man are
much broader than those of any animal, and admit of being separat-
ed more widely from each other. The sources of the latter preroga-
tive reside in the superior breadth of the human pelvis, and in the
length and obliquity of the neck of the femur, which by throwing the
body of the bone outwards, disengage it from the hip-joint.

The whole tarsus, metatarsus, and toes, rest on the ground in the
human subject, but not in other animals. The simiae, and the bear,

See also Landseer's Engravings of Lions, Tigers, Panthers, and Leopards. Lond.
1823 ; a work distinguished by the beauty of its execution, and exhibiting
most striking illustrations of character and expression in the nobler carnivorous
animals.

* Lordat Svr I' Anatomie du Singe Vert. p. 42.

f Aristotle De Partibus Aiämalium, 4, 10.

X 2

308 ON THE MUSCLES.

have the end of the os calcis raised from the surface ; while on. the
contrary it projects in man, and its prominent portion has a most im-
portant share in supporting the back of the foot. The exterior margin
of the foot rests chiefly on the ground in the simise ; which circum-
stance leaves them a freer use of their thumb and long toes in seizing
the branches of trees, &c. ; and renders the organ so much the less
adapted to support the body on level ground.

The plantaris muscle, instead of terminating in the os calcis, ex-
pands into the plantar fascia in the simiae : and in other quadrupeds
it holds the place of the ßexor brexns, or perforatus digitorum pedis,
passing over the os calcis in such a direction that its tendon would
be compressed, and its action impeded, if the heel rested on the
ground.

The extensors of the ankle joint, and chiefly those which form the
calf of the leg, are very small in the mammalia, even in the genus
simia. The peculiar mode of progression of the human subject suflfi-
ciently accounts for their vastly superior magnitude in man. By ele-
vating the OS calcis they raise the whole body in the act of progres-
sion ; and by extending the leg on the foot, they counteract that
tendency which the weight of the body has to bend the leg in stand-
ing-

The thigh is placed in the same line with the trunk in man ; it al-
ways forms an angle with the spine in animals ; and this is often even
an acute one. The extensors of the knee are much stronger in the
human subject than in other mammalia, as their double effect of ex-
tending the leg on the thigh, and of bringing the thigh forwards on
the leg forms a very essential part in the human mode of progres-
sion.

The flexors of the knee are, on the contrary, stronger in animals ;
and are inserted so much lower down in the tibia (even in the simise),
than in the human subject, that the support of the body on the hind
legs must be very insecure ; as the thigh and leg form an angle, in-
stead of continuing in a straight line.

The gluteus juaximus, which is the largest muscle of the human
body, is so small and insignificant in animals, that it may almost be
said not to exist. This muscle, which forms the great bulk of the
human buttock, extends the pelvis on the thighs in standing ; and,
assisted by the other two glutei, maintains that part in a state of equi-
librium on the lower extremity, which rests on the ground, while the
other is carried forwards, in progression. The true office of these
important muscles does not therefore consist, as it is usually represent-
ed, in the common anatomical works, in moving the thigh on the pel-
vis, but in that of fixing the pelvis on the thighs, and of maintaining
it in the erect position.

Such then are the supports by which the trunk of the human body
is firmly maintained in the erect position. The properties of the
trunk, which contribute to the same end, do not so immediately be-
long to the present part of the work ; but may be slightly mentioned,

ON THE MUSCLES. 309

to complete the view of the subject. The breadth of the human pel-
vis affords a firm basis on which all the superior parts rest securely ;
the same part is so narrow in other animals, that the trunk represents
an inverted pyramid ; qnd there must consequently be great difficulty
in maintaining it in a state of equilibrium, if it were possible for the
animal to assume the erect position. In those instances, where the
pelvis is broader, the other conditions of the upright stature are ab-
sent ; the bear, however, forms an exception to this observation, and
consequently admits of being taught to stand and walk erect, although
the posture is manifestly inconvenient and irksome to the animal.

The perpendicular position of the vertebral column under the cen-
tre of the basis cranii, and the direction of the eyes and mouth for-
wards, would be as inconvenient to man, if he went on all-fours, as
they are well adapted to his erect stature. In the former case he
would not be able to look before him ; and the great weight of the
head, with the comparative weakness of the extensor muscles, and
the want of ligamentum nuchae, would render the elevation of that or-
gan almost impossible.

When quadrupeds endeavour to support themselves on the hind
extremities, as, for instance, for the purpose of seizing any objects
with the fore feet, they rather sit down than assume the erect posi-
tion. For they rest on the thighs as well as on the feet, and this can
only be done where the fore part of the body is small, as in iheshnicef
the squirrel, &c. ; in other cases, the animal is obliged also to support
itself by the fore feet, as in the dog, cat, &c. The large and strong
tail, in some instances, forms as it were a third foot, and thereby in-
creases the surface for supporting the body ; as in the kangaroo and
ihejerboa.

Various gradations may be observed in the mammalia, connecting
man to those animals which are strictly quadrupeds. The simite,
which are by no means calculated for the erect position, are not, on
the other hand, destined like the proper quadrupeds to go on all
fours. They live in trees, where their front and hinder extremities are
both employed in climbing, &c,

The true quadrupeds have the front of the trunk supported by the
anterior extremities, which are consequently much larger and stronger
than in man ; as the hind feet of the same animals yield in these re-
spects to those of the human subject. The chest is in a manner sus-
pended between the scapulae ; and the serrati magni muscles, which
support it in this position, are consequently of great bulk and
strength. When viewed together they represent a kind of girth sur»
rounding the chest.

§ 304. Of the muscles which do not exist in man, nor as far
as we hitherto know, in the rjuadrumana, but which on the
contrary are found at least in the greatest number of quadru-
peds ; the cutaneous expansion of the trunk (panniculus car-

310 ON THE MUSCLES.

nosus, expansio cornea, musculus suhcutaneus), and the sus-
pensorius oculi,^ deserve particular mention.

The panniculus carnosus does not exist in the pig ; but is of
extraordinary strength in such animals as have the power of
rolling themselves up ; as the tatu, {armadillo) manis, porcu-
pine, hedgehog, &c."|'

The tendinous fibres of this cutaneous expansion may be
split into threads of a hundred feet or more in length in the
ceiacea ; and the inhabitants of the Aleutian islands prepare
in this way a very delicate kind of thread.

§ 305. Among such, on the contrary, as are found only in
particular genera and species, the most remarkable are the ex^
tremely numerous muscles of the prehensile tails of some cer'
copitheci {sapajous, belonging to the simice of Linnaeus), and
other South American and Australasian mammalia ;!f: those
which we have already described in the trunk of the elephant ;§
and that which belongs to the epiglottis of several mammalia
{cerato-epiglottid£Bm).\\

% 306. Other muscles, which are common to most orders of
the class, are distinguished in some species by remarkable
strength, which adapts them for peculiar kinds of motion.
This is the case with the gluteus medius^ of the horse ; which
in connexion with some others, particularly the gemellus,**

^ Zinn, in Comment. Soc. Reg. Scient. Getting, torn. i. p, 48,

+ See the excellent monograph of Himly, iiher die Zusammenkugeln des Igels,
Brunswick, 1801, 4to.

t Mery reckoned no less than 280 muscles in the prehensile tail of a eercopithe-
cits. Du Hamel, Hist. Acad. Reg. Sclent, p. 276.

§ See the interesting observations of Cuvier on the organization of the elephant's
trunk, in the seventh part of the Menagerie du Museum National. He intends to ex-
plain the wonderful structure of this completely unique organ in a separate work,
with twelve plates. Some remarks on the subject may be found in the valuable De-
scription anatomique d'un Elephant male, par P. Camper, publi'e par son fils, A. G.
Camper. Paris, 1802, folio.

II J. G. Hunge De Voce ejusque Organis. Lugd. Bat. 1753, 4to.

^ Stubbs's Muscles, tab. 2, q, r, s, t; and tab. 3, a, b, c, d.

** Ibid, tab. 3, 60-64.

ON THE MUSCLES. 311

enables the animal to kick out backwards with such astonish-
ing force ; with the immensely long flexors of the beaver's
tail, or the extensors of tlie kangaroo, &c.

The pectoralis major, latissimus dorsi, and teres major, are of vast
size in the mole ; and enable the animal to dig its way under ground,
and to throw up the earth.

BIRDS.

I 307. The muscles in this class are distinguished by pos-
sessing a comparatively weak, irritable power, which is soon
lost after death ; and by their tendons becoming ossified, as
the animal grows old, particularly in the extremities, but some-
times also in the trunk. I have observed this to a very remark-
able degree in the crane.

This appearance led several physiologists of the seven-
teenth century to the erroneous conclusion, that the bones in
general, at least for the most part, are formed from tendons.*

§ 308. The most remarkable circumstances in the myology
of this classf have been incidentally mentioned in previous
parts of this work. For instance, muscles which are not ex-
clusively peculiar to birds, but are more commonly found in
them than in the mammalia, as those of the membrana nicti-
tans ;J or such as are deficient, as the diaphragm ; or distin-
guished by their remarkable size and peculiar form, as the pec-
toral muscles.

Birds possess three pectoral muscles, arising chiefly from their
enormous sternum, and acting on the head of the humerus. The first,
or great pectoral, weighs, of itself, more than all the other muscles of
the bird together. The keel of the sternum, the fork, and the last
ribs, give origin to it ; and it is inserted in a rough projecting line of
the humerus. By depressing that bone, it produces the strong and

* See Stenonis De Museulis et Glandulis, p. 26. Casp. Bartholin Specimen His-
toric AnatomiccB Partium Coiyoris Humani, p. 185.

f On the myology of birds the reader may consult Stenonis, in the Act. Hafniens.
1673, p. 6 ; and Valentini, Amphitheat. Zootom. pt. 2, p. 8.

Also Vicq d'Azyr, in the M^m. de I' Acad, des Sciences de Paris, 1772. Merrem's
Vermischte Abh. aus der Tkiergesch. p. 144.

And Wiedemann's Archives, vol. ii. p. 68.

i These muscles are described in the chapter which treats on the eye.

312 ON THE "MUSCLES.

violent motions of the wing, which carry the body forwards in flying.
The middle pectoral lies under this ; and sends its tendon over the
junction of the fork, with the clavicle and scapula, as in a pulley, to
be inserted in the upper part of the humerus ; which bone it elevates.
By this contrivance of the pulley, the elevator of the wing is placed
at the under surface of the body. The third, or lesser pectoral
muscle, has the same effect with the great pectoral, in depressing the
wing.

One of the flexor tendons of the toes of birds (produced from a
muscle which comes from the pubis) runs in front of the knee ; and
all these tendons go behind the heel ; hence the flexion of the knee
and heel produces mechanically a bent state of the toes, which may be
seen in the dead bird ; and it is by means of this structure that the
bird is supported, when roosting, without any muscular action.

This circumstance of the flexion of the toes accompanying that of the
other joints of the lower extremity of birds, was long ago observed by
Borelii, and attributed by him to the connexion which the flexors of the
toes have with the upper parts of the limb, by which they are mechani-
cally stretched when the knee is bent. This explanation has been con-
troverted by Vicq d'Azyr and others, who have referred the effect to
the irritability of the muscles. The opinion of Borelii appears, not-
withstanding, to be well founded ; for not only the tendon of the ac-
cessory flexor passing round the knee, but the course of the flexor
tendons over the heel, and along the metatarsus, must necessarily
cause the contraction of the toes, when either of these joints is bent ;
and if the phenomenon was not produced on mechanical principles, it
would be impossible for birds to exhibit it during sleep, which they
do, or to prove the effect on the limb of a dead bird, than which no-
thing is more easy. The utility of this contrivance is great in all
birds, but particularly so in the rapacious tribe, which by this means
grasp their prey in the very act of pouncing on it ; and it is stili
more necessary to those birds which perch or roost during their
sleep, as they could not otherwise preserve their position, when all
their voluntary powers are suspended. Rees's Cyclofedia, art.
Birds.

AMPHIBIA,

§ 309. The two chief divisions of this class are distinguished
from each other by a remarkable difference in their muscular
structure, which arises from a corresponding diversity in the
skeleton. In the reptiles, for instance, and particularly in the
turtles^ dixxdi frogs, where the trunk of the skeleton possesses
but little mobility, the muscles are very few in number. Not

* For the myology of the testudo tabulata see Wiedemann's Archives, vol. iii. pt. 2,
78.

ON THE MUSCLES. 31S

only the diaphragm, but also the muscles of the abdomen and
chest are wanting in the genus iesfudo. The other muscles
are, however, of vast strength in this genus. In the serpents,
on the contrary, they are more uiniform and thin, and more
numerous, beyond all comparison, in consequence of the vast
number of vertebrae and ribs, and the want of all external
organs of motion.

FISHES.

§ 310. The muscles of this class* are distinguished from
those of animals which breathe by means of lungs, not only
by receiving a smaller supply of blood, and consequently being
of a paler colour, but also by their disposition in layers, and
by the uniformity "f of their substance, which in general is
destitute of tendinous fibres. This structure, together with
the number and bulk of their muscles, is well calculated to
support that great expenditure of strength and exertion,
which is a necessary consequence of the peculiar abode, and
whole economy of these animals.:]:

INSECTS.

§311. The observations which have just been made con-
cerning the uniformity, number, and strength of the muscles
of fishes will hold equally good, on the whole, of insects; but
under other modifications, and generally in a more striking
degree.^ In the few which have been hitherto investigated
with a view to this subject, some differences have been ob-
served. The immensely strong muscles of the claw in the
crab and lobster,\\ bear considerable analogy to those in some

* Lacepede, Hist. Naturelle des Poüsons, torn. i. Discours, p. 47.

Sir A. Carlisle, On the Arrangement and Mechanical Action of the Muscles of Fishes
in the Phil. Trans. 180G.

f Kielmeyer, über die Verhältnisse der Organischen Kräfte untereinander, p. 22,
Bvo. 1793, Stutgard.

X Dr. Blane's Lecture on Muscular Molion, p. 54.

$ Kielmeyer, loco citato,

H Stenonis Specimen EUmentorum Myologia, p. 55.

Pcnault,

314 ON THE MUSCLES.

organs of red-blooded animals; while the muscles of other
insects, as may be seen in the larvae, are distinguished by a
peculiar bluish white colour, and flattened form. Their great
number concurs also with these characters in distinguishing
them from those of the former classes. Lyonet* reckoned
4,061 in the larva of the cossus,-\- and 2,186 of these belong to
the alimentary canal.

VERMES.

§ 312. The arrangement of the muscular system of the
mollusca % has considerable analogy, on the whole, to that of
the larvae of insects. Those which inhabit shells have, more-
over, peculiar muscles connecting them to their testaceous
covering, and enabling them to move it. Thus the snail has
large muscular fasciculi running along the abdomen, attaching
it to the upper turn of the shell, and enabling the animal to
withdraw itself into the cavity. The bivalves have powerful
adductor muscles to close their shells. § In several of the
mollusca nuda there is a considerable apparatus of cutaneous
fibres, by which a very remarkable shortening of the body
can be produced. A similar and very astonishing contractile
power resides in the gelatinous parenchyma of the zoophytes^
and animals which inhabit corals, in whose structure nothing
like muscular fibres can be distinguished.

Perraillt, 'Es&avs de Physique, torn. iii. tab. 4, fig. 3.

And especially F. Succow, Specimen Myologies Insectorum de astaco FluvieUiM.
Heidelb. 1813.

* Tab. 6, 7, 8, 15, 16, 17 ; and tab. 5, fig, 7, 8.

t This number includes about ten times as many as belong to the human body.

} See an account of the muscles of the aphrodite aculeata, in Pallas's Miscellanea
Zoologica, tab. 7, fig. 13.

Of tlie tritonia aplyda, &c. by Cuvier, in the Annales du MusSum National d'Hist^
Nat. torn. i. and ii.

Of the snail, (Mix pomatia) by Swammerdam, tab. 6, fig. 2 ; of numerous bi-
valves and multi valves in several figures of Poli's work.

§ Hunter, 0« i/ie B/ood, p. 111. Poli, vol. i. Introduction, p. 59.

THE GENERATIVE FUNCTIONS.

317

THE GENERATIVE FUNCTIONS,

CHAPTER XXIII.

ON THE MALE ORGANS OF GENERATION.

§ 313. In considering the comparative anatomy of the sexual
functions, we must confine ourselves to those animals which
possess male organs, destined for the purpose of impregnation,
and female parts for that of conception.

To the former belong chiefly the testes, vesiculae seminales,
prostate and penis. Yet the three last mentioned parts, and
particularly the vesiculae and prostate, are by no means con-
stantly found even in red-blooded animals.

The following general view of the subject of generation, in the
5th volume of Legons d' Anatomie comparee, affords a comparative
statement of the manner in which that function is executed in the
different classes.

The nature of generation, which is the greatest mystery in the
economy of living bodies, is still involved in impenetrable obscurity.
The creation of a living body, that is, its formation by the union of
particles suddenly brought together, has not hitherto been proved by
any direct observation. The comparison of this process to that of
crystallization is founded in a false analogy : crystals are formed of
similar particles attracting each other indifferently, and agglutinated
by their surfaces, which determine the order of their arrangement :
living bodies, on the contrary, consist of numerous fibres or laminae
of heterogeneous composition, and various figures, each of which
has its peculiar situation in relation to the other fibres and lamina?.
Moreover, from the instant in which a living body can be said to

^18 ON THE MALE ORGANS OF GENERATION.

«exist, however small it may be, it possesses all its parts ; it does not
grow by the addition of any new laminae, but by the uniform or
irregular development of parts which existed before any sensible
growth.

The only circumstance common to all generation, and consequently
the only essential part of the process, is, that every living body is
attached at first to a larger body of the same species with itself It
constitutes a part of this larger body, and derives nourishment for a
certain time from its juices. The subsequent separation constitutes
birth ; and may be the simple result of the life of the larger body,
and of the consequent development of the smaller, without the addi-
tion of any occasional action.

Thus the essence of generation consists in the appearance of a
small organized body in or upon some part of a larger one, from
which it is separated at a certain period, in order to assume an inde-
pendent existence.

All the processes and organs which co-operate in the business of
generation in certain classes, are only accessory to this primary
function.

When the function is thus reduced to its most simple state, it con-
stitutes the gemmiparous, or generation by shoots. In this way the
buds of trees are developed into branches, from which other trees
may be formed. The polypes {hydra') and the sea anemones (actinia)
multiply in this manner ; some worms are propagated by a division
of their body, and must therefore be arranged in the same division.
This mode of generation requires no distinction of sex, no copula-
tion, nor any particular organ.

Other modes of generation are accomplished in appropriate or-
gans ; the germs appear in a definite situation in the body, and the
assistance of certain operations is required for their further develop-
ment. These operations constitute fecundation, and suppose the
existence of sexual parts ; which may either be separate or united in
the same individual.

The office of the male sex is that of furnishing the fecundating or
seminal fluid ; but the manner in which that contributes to the deve-
lopment of the germ is not yet settled by physiologists. Some,
forming their opinions from the human subject and the mammalia,
where the germs are imperceptible before fecundation, suppose that
these are created by the mixture of the male fluid with that which
they suppose to exist in the female ; or that they pre-exist in the
male semen, and that the female only furnishes them with an abode.
Otliers consult the analogy of the other classes of animals and of
plants. In several instances, particularly in the frog, the gerrn may
be clearly recognized in the ovum before fecundation; its pre-
existence may be concluded in other cases, from the manner in which
it is connected to ihe ovum when it first becomes visible ; for it is
agreed on all sides that the ovum exists in the female before fecun-
dation, since virgin^ hens lay eggs, &c. From such considerations

ON THE MALE ORGANS OF GENERATION. 319

these physiologists conclude that the germ pre-exists in all females-;
and that the fecundating liquor is a stimulus which bestows on it an
independent life, by awakening it, in a manner, from the species of
lethargy in which it would otherwise have constantly renaained.

The origin of the germs, and the mode of their existence in the
female ; whether they are formed anew by the action of life, or are
pre-existent, and inclosed within each other ; or whether they are
disseminated, and require a concourse of circumstances to bring them
into a situation favourable for their development, are questions
which, in the present state of our knowledge, it is utterly impossible
for us to decide. These points have for a long time been agitated
by physiologists, but the discussion seems now to be abandoned by
universal consent.

The combination of the sexes and the mode of fecundation are
subject to great variety. In some instances they are united in the
same individual, and the animal impregnates itself. The acephalous
mollusca and the echinus exemplify this structure. In others, al-
though the sexes are united in each individual, an act of copulation
is required, in which they both fecundate and are fecundated. This
is the case with the gasteropodous mollusca and several tvorms. In
the remainder of the animal kingdom the sexes belong to different
individuals.

The fecundating liquor is always applied upon, or about the germs.
In many cases the ova are laid before they are touched by the semen;
as in some fishes of the bony division, and the cephalopodous mol-
lusca. Here, therefore, impregnation is effected out of the body ; as
it is also in the frog and toad. But in the latter instances the male
embraces the female, and discharges his semen in proportion as she
voids the eggs. In most animals the seminal liquor is introduced
into the body of the female, and the ova are fecundated before they
are discharged. This is the case in the mammalia, birds, most rep'
tiles, and some ßshes ; in the hermaphrodite gasteropodous mollusca,
in the Crustacea, and insects. The act by which this is accomplished
is termed copulation.

In all the last mentioned orders ova may be discharged without
previous copulation, as in the preceding ones. But they receive
no further development, nor can they be fecundated when thus
voided.

The effect of a single copulation varies in its degree ; it usually
fecundates one generation only ; but sometimes, as in poultry, seve-
ral eggs are fecundated ; still, however, they only form one gene-
ration.

In a very few instances one act of copulation fecundates several
generations, which can propagate their species without the aid of the
male. In the plant-louse {aphis) this has been repeated eight times ;
and in some monocuH twelve or fifteen times.

When the germ is detached from the ovary, its mode of existence
may be more or less complete. In most animals it is connected, by

S2Ö ON THE MALE ORGANS OF GENERATION

means of vessels, to an organized mass, the absorption of which
nourishes and developes it until the period of its birth. It derives
nothing, therefore, from the body of the mother, from which it is se-
parated by coverings varying in number and solidity. The germ,
together with its mass of nourishment, and the surrounding mem-
branes, constitutes an egg, or ov7i?n ; and the animals which produce
their young in this state are denominated oviparous.

In most of these the germ contained in the egg is not developed
until that part has quitted the body of the mother, or has been laid;
whether it be necessary that it should be afterwards fecundated, as
in many fishes ; or require only the application of artificial heat for
its incubation, as in birds ; or that the natural heat of the climate is
sufficient, as in reptiles, insects, &c. These are strictly oviparous
animals.

The ovum, after being fecundated, and detached from the ovarium,
remains in some animals within the body of the mother, until the
contained germ be developed and hatched. These are false vivipa'
reus animals, or ovo-viviparous. The viper, and some fishes afford
instances of this process.

Mammalia alone are truly viviparous animals. Their germ pos-
sesses no provision of nourishment, but grows by what it derives
from the juices of the mother. For this purpose it is attached to the
internal surface of the uterus, and sometimes, by accident, to other
parts, by a kind of root, or infinite ramification of vessels, called a
placenta. It is not, therefore, completely separated from the mother
by its coverings. It does not come into the world until it can enjoy
an independent organic existence. The mammalia cannot, therefore,
be said to possess an ovum in the sense which we have assigned to
that term.

From the above view of the subject, generation may be said to
consist of four functions, differing in their importance, and in the
number of animals to which they belong.

1st, The production of the germ, which is a constant circumstance ;
2ndly, fecundation, which belongs only to the sexual generation ;
3dly, copulation, which is confined to those sexual generations, in
which fecundation is accomplished within the body.

Lastly, uterogestation, which belongs exclusively to viviparous ge-
neration. Cuvier, Legons d'Anat. comparee, tom. v.

§ 314. The testes, and sometimes the vesiculae seminales
and prostate, vary most remarkably in their magnitude in such
animals as have a regular rutting season.* They are very
diminutive at other periods of the year, but swell at that
particular time to a comparatively vast magnitude. This

* See Dr. Jenner On the Migration of Birds, in the Phil. Trans. 1823.

ON THE MALE ORGANS OF GENERATION, 321

change is particularly observable in the testes of the mole,
sparrow, and frog.*

§ 315. It is necessary to mention here, in a cursory and ge-
neral manner, the peculiar organs possessed by the males of
some specievS, for the purpose of holding the female during
the act of copulation. Of this kind are the spur on the hind
feet of the male ornitJiorhynchus /-f* the rough black tubercle,
formed in the spring season on the thumb of the common
frog ; the two members, formed of bones articulated to each
other, near the genitals of the male torpedo and other cartila-
ginous fishes,' the forceps on the abdomen of the male
dragon-fly, &c, Ray, Klein, Battara, and others, considered
these parts as real organs of generation ; and the same mistake
was committed by Menz and Krüger concerning the tubercles
on the thumb of the frog. Equally erroneous is the opinion
of Tyson, that the sternum of the cyclopterus lumpus (Jumpr,
sucJier) serves the male to retain the female ir) its embrace in
the act of impregnation ; an opinion which that physiologist
entertained, from an idea that such an organ would be pecu-
liarly useful to the animal, on account of the shortness of its^
penis. To say nothing of the situation of the sternum on the
neck, together with the convexity of the abdomen being cal-
culated rather to impede than to assist the act of copulation,
and also of the existence of this organ in both the male and
female, it has escaped the notice of that otherwise excellent
physiologist that these fishes do not copulate. The female
deposits the ova alone at the spawning season, as is the case

* In animals, wliicl) have lost the testes by the operation of castration, a similar
circumstance may be observed in some of the remaining organs ; as in the vesiciilae
seminales of the gelding. Bourgelat, El^mens de I' Art V^thinaire. Par. 1769, 8vo.
p. 359.

t The spur of the ornithorhynchus not only enables the animal to retain the female
in a firm position, but probably acts as a specific stimulant during the act of copu-
lation. On the subject of this peculiar organ see Rudolphi, in the Abhandl. der
Berlinei: Wispersch, 1820.

Seifert, Spicitegüi Admologica, p, 8, tab. 1 , fig. .0.

Meckel's Archiv, vol, viii.

32^ ON THE MALE ORGANS OF GENERATION!

with many other species of fishes, and the deposited ova are
afterwards fructified by the male.

MAMMALIA.

§ 316. A scrotum, or bag, in which the testes hang on the
outside of the abdominal cavity exists only in the mammalia ;
but is not by any means common to all the genera. It is not
found, and that for very obvious reasons, in the aquatic ani-'
inals of this class ; nor in the perfect subterranea (those which ,
live under ground,) as the mole ; nor in such as roll themselves
lip on the approach of danger, as the hedgehog. These,
which may be called true testiconda, (i. e. animals having
their testes concealed) must be distinguished from such as
have the power of withdrawing these glands from the abdo-
men, and retracting them into the cavity according to circum-
stances ; as the guinea-pig, * the squirrel, the rat, the
hamster, t {marmota cricetus) and Canadian musk-rat J (mtis
-ssibethicus).

In those testiconda which have the penis much concealed
by the integuments in its unerected state, as the hare, cat, &c.
it is difficult sometimes to distinguish the sexes on the first
view, particularly at an early age.

A scrotum exists in all the quadrumana and in most of the Carni-
vora ; in animals of the opossum kind, which have it in front of the
pelvis ; in the hare and gerboa ; in most of the ruminating genera,
and in the solidungula.

The testes are placed under the skin of the perineum in the pachi/-
dermata and the civet ^ or under that of the groin, as in the camel and
otter. They pass from the abdomen into one or the other of these
situations, particularly at the rutting season, in the bats, the mole,
shrew, and hedgehog ; and in several rodentia, as the rat, guinea-
pig, porcupine, beaver, squirrel, &c. They remain constantly in the
abdomen in the ornithorhynchus paradoxus and hystrix, in the elephant,
hyrax, the amphibious mammalia, and the ceiacea.

* Frealev, Monographia caviaporcelli Zoologica. Getting. 1820, p. 54.

t Sulzer, pp. 38, 67.

i Sarrazin, in the Mem. de I'Acad. des Sciences de Paris, 1725.

Seiler De testiculorum ex abdomine in scrotum descensu. Lips. 1817, p. 33, tab. 2,

ON THE MALE ORGANS OF GENERATiON." 323'

The tunica vaginalis exists constantly in the mammalia. As the-
horizontal position of the body obviates the danger of hernise, the^
cavity of this covering always communicates by means of a narrow^
canal with the abdomen, in such animals as have the testes remaining
constantly in the scrotum. Where these glands occasionally pass
out of the abdomen and return again, the communication is very
broad and free.

§ 317. In several quadrupeds, as the dog, horse, ram, and
others, there is a body composed of condensed cellular sub-
stance, lying according to the axis of the testicle near the
epididymis, and knovv^n by the name of corpus Highmori^
This is not a canal, nor does it possess that artificial structure
which has been described and delineated by several anatomists
of the seventeenth century.*

The seminal tubes are collected in some animals into large fasci-
culi ; as in the baboons, most of the large Carnivora, the wild boar,
and the rhinoceros. It is the union of the septa which divide these
fasciculi, that constitutes the corpus Highmori. In most of the
rodentia, and particularly in the rat, these tubes are large and pa-
rallel, and very easily separable.

The vasa deferentia are usually enlarged in size, and assume a
cellular structure for some short distance previous to their termina-
tion. The structure of this part is the most remarkable in the horse ;
where " the vas deferens, in passing over the bladder, enlarges to
the size of the human thumb ; this amplification extends from ite
entrance into the urethra to the distance of five or six inches from
that point, where it again becomes of its ordinary diameter.

" The inside of this enlargement is composed of cells, and some-
what resembles in construction the cells of the corpus cavernosum
penis, passing in a transverse direction across the tube. In the
centre of this enlargement passes the small canal of the vas deferens;
each cell communicates by one, two, or more small pores with the
canal of the vas deferens, and the cells diminish as they approach
the neck of the bladder, till they are lost in a smooth passage enter-
ing the urethra.

" What the purpose of this structure is, does not appear ; it must
retard the passage of the semen, and probably adds some fluid to it.

• De Graaf De Vinrr. Organis General, inserinent. tab. 3, fig. 4, in the dog.
See also the excellent delineations by A. Monro, junior, De Testibus. Edinb.
1755, 8vo. tab. 4, fig. 5, in the dog; fig. 8, in the horse; tab. 3, fig. 5, in the pig,

Y 2

324 ON THE MALE ORGANS OF GENERATION.

secreted from the cells themselves." Mr. Clark in Rees's Ci/clopedia,
art. Anatomy of the Horse.

The cells of this part contain a thick white fluid, which flows out
in abundance on compression.

An analogous structure is met with in the ram.

§ 318. Most species of mammalia, and, with the exception
of the cetacea, some out of every other order in the class
possess vesiculcB seminales. Mr. Hunter, at least, expressly
asserts that these parts are not found in the cetacea.^ I am
indeed aware of the common opinion, which supposes the first
discovery of these important parts to have been made in the
dolphin, by that excellent zootomist Rondelet, to whose la-
bours the science is so much indebted'. But the passage
quoted for this purpose from his classical worki* seems to me
to be quite as inadequate to prove that point, as the observa-
tion of Ray on the male organs of the porpoise^ which has
also been applied by Haller to the vesiculae seminales. The
vesiculas seminales swell to a vast size in the rutting season in
many animals, as in some of the simice, and most particularly
in the hedgehog.^

Among the species in w^hich these parts do not exist, are
the dog and cat kind, the bears, the opossums, sea-otters, seals,
and the ornithorh^nchus.

The following animals have no vesiculae seminales, according to
Cuvier : the plantigrada, except the racoon and hedgehog ; all the
Carnivora and marsupial animals ; the ruminantia, the seals, the ce-
tacea, and the two species of ornithorhynchus. Their existence or
absence does not seem to follow any general law.

Their form and structure vary almost infinitely in the different
mammalia, where they often terminate in the urethra by a separate
opening from that of the vas deferens. This circumstance, together
with the fact of their containing generally a fluid of different appear-
ance and properties from those of the semen, and the glandular struc-
ture which their coats possess in many instances, militates strongly

* Philos. Trans, vol. Ixxvii, p. 442.

t Piscibus Marinis, p. 461.

4; Philos, Trans, vol. vi.

$ Wetter, Anatome erinacei Europai. Gotting. 1818, p. 61, tab. 3, fig. 1, 2.

ON THE MALE ORGANS OF GENERATION. 325

against the opinion which considers these vesicles as reservoirs of
the semen, and incHnes us to suppose with Mr. Hunter, that they
add a pecuhar secretion of their own to the fluid which comes from
the testes.

See Mr. Hunter's remarks on the vesiculse seminales, in his Ob-
servations on certain Parts of the Animal Economy, p. 27 et seq.

In the hedgehog these parts are of a vast size, much exceeding
the volume of the testes. They form four or five bodies on each
side, consisting of a small and infinitely convoluted tube, and open
separately into the urethra. The rodentia are generally distinguished
by the great size of their vesicles. These parts in the guinea-pig
are long, uniform, cylindrical cavities, containing generally a firm
cheesy matter. In the boar they are very large, and of a lobulated
structure ; a common excretory duct receives the branches from the
lobes. In the horse they form two large and simple membranous
bags, opening near the vasa deferentia, but separately.

§ 319. The possession of a prostate (in some instances sim-
ple,, but generally divided into two parts) is peculiar to the
mammalia, and seems to take place in every species of the
whole class. In many animals at least, where its existence
has been denied, as in the goat and ram, considerable glan-
dular bodies are found, which bear a greater resemblance to
the prostate than to Cowper's glands.*'

§ 320. In many species the penis consists of a single corpus
cavernosum, without any septum. The pig and the cetacea
furnish examples of this structure ; and in the latter animals
there are numerous tendinous layers crossing it.-j*

In some species, where the act of copulation requires a
longer portion of time, as in the dog, badger, &c. the corpus
spongiosum of the glans, and of the posterior part of the
penis, swells during the act much more considerably than the
rest of the organ, and thus the male and female are held to-
gether during a sufficient space of time for the discharge of
the seminal fluid.:|:

It has been doubted whether the swelling of the corpus spongiosum

• HjJler, in Comment. Soc. Reg. Scient, Getting, torn. i. tab. 1.
t Ruysch, Epist. Problemat. 15, tab. 19, fig. 5.

X Daubenton, torn. v. tab. 47 ; and Walter, M6moire sur U Blaireau, in the M^m.
d« CAcud. de Berlin, 1792, p. 20.

S^6 ON THE MALE ORGANS OF GENERATION.

iVi dogs does not frequently occasion a protracted and painful adhe-
sion long after the purposes of coition are completed, but Blumen-
bach's explanation coincides with that of the Roman poet and
physiologist.

" In tri viis non s^pe canes discedere aventes,
Divorsi cupide summis ex viribu' tendunt.
Cum interea validis Veneris compagibus hasrent "?
Quod facerent nunquam nisi mutua gaudia nossent.'*

Lucret. lib. iv.

In the quadrumana and bats the penis hangs loose from the pubis
as in man. In most of the other mammalia it is contained in a
^heath of the integuments, which extends nearly to the navel. This
sheath has an adductor and a retractor muscle. The penis is gene-
rally folded when drawn within the sheath, on account of its length.
In some animals it turns back when it has reached the front of the
pubis, and passes out near the anus ; this is the case with the guinea-
pig, marmot, and squirrel. It goes directly backwards from the
beginning in the hare, rat, dormouse, and opossum, where the pre-
puce is found close to the anus.

The corpora cavernosa form a cylindrical ring in the kangaroo,
and the urethra passes in the centre.

Mr, B. Clark has given us the following interesting observations
on the penis of the horse, in his description of the anatomy of that
animal in the 2nd vol. of Rees's Cydopcedia, art. Anatomy of the
Horse.

" We have remarked that the penis of the horse possesses a volun-
tary power of erection, not known to the human, nor perhaps to
most other animals. This power is exerted on making water, and
though the erection is not very considerable, it is yet sufficient to
bring the penis from its sheath, which is effected apparently by its
increased gravity, from blood accumulating in the cavernous cells of
this part. After staling this semi-erection of the penis subsides,
and it is again retracted within the sheath. This operation, though
occurring daily to the sight of every one, has not, it is apprehended,
been noticed by any veterinary writer.

'* The urethra of the horse is muscular from one extremity to the
other, being formed on the outside of strong transverse fleshy fibres,
,and supported by a strong ligament.

" In the glans of the penis, immediately over the opening of the
urethra, externally, there is a large cell or cavity, smooth on the in-
side, and lined with a membrane which secretes a brown unctuous
substance for the lubrication of the penis, and defending it from the
corrosive effects of the urine ; another cell of a similar description
with the former is observable on the side of the urethra, and nearly
surrounding it ; it is separated from the former by a jnembranous
partition.

" The apparently unctuous secretion above described is miscible
with water ; it burns, however, in the fire like an oily substance, and

ON THE MALE ORGANS OF GENERATION. 327

is not soluble in spirits of wine or nitrous acid, nor does it dry on
exposure to the air during several weeks.

" There is nothing resembling a frenum to the penis of the horse.

" The cavernous body has no longitudinal septum.

" Another singularity in the genital parts of this animal is, that
there is an immense congeries of veins, lying on the back of the penis,
which are filled during copulation, forming an elevation nearly as
large as the penis itself; these veins communicate with both the ca-
vernous and spongious bodies,"

§ 321. Several species of mammalia, both among those
which possess no vesiculse seminales, and thereby require a
longer time for completing the act of copulation, and those
which are not distinguished by this peculiarity, possess a pecu-
liar bone in the penis, generally of a cylindrical form, but some-
times grooved. This is the case with some of the simics, most
of the hat-Jchid, the hamster, and several others of the mouse-
hind, the dog, hear, badger, weasel, seal, walrus, &c. A simia
cynomolgus, which I lately dissected, had a small os penis,
with large vesiculse seminales. Delineations of this bone in
several species of animals may be seen in Redi,* and in the
works of Meyer and Daubenton. It is somewhat remarkable
that this bone should not be found in all the species of the
same genus. Thus it is wanting in several simice, in some
bats, and in the hyena of the dog-kind.f

§ 322. In most of the male animals of this class the urethra
runs on to the end of the glans, and forms a common passage
for the urine, prostatic liquor, and semen. In some few spe-
cies, the passage which conducts the two former fluids, is dis-
tinct from that of the seminal liquor. The bifid fork-like
glans of the o2}ossum% has three openings, one at the point of
bifurcation for transmitting the urine ; and two for the semi-
nal fluid at the two extremities of the glans. The short ure-
thra of the ornithorhynchus paradoxus opens directly into the

• De Viventibus intra Viventia, tab. 26.

t See J. F. Hermann, Observat.ex Osteol.comparat, Argent. 1792, p. 13.

t Cowper, in the Phitos. Trans, vol. xxiv. p. 1583, fig. 2-5. Among other pecu-
liarities of this singular animal it may be mentioned, that the penis lies behind" the
scrotum.

ON THE MALE ORGANS OF GENERATION.

cloaca, and the large penis of the animal serves merely to con-
duct the seminal fluid. It divides into two parts at its extre-
mity, and each of these is furnished with sharp papillae, which
are perforated for the passage of the semen.* A similar
structure obtains in the ornithorhynchus hystrix, where the
penis divides into four glandes.f

§ 323. In some species of the cat^kind the glans is covered
with retroverted papillae, which, as these animals have no ve-
siculae seminales, may enable the male to hold the female longer
in his embraces. In a collection at Hanover there is a penis
which must have belonged to a tiger, or some similar species ;
where the lower part of the glans is furnished with two strong
horny processes divided each into three points, which are
turned backwards. Similar horny processes are found in the
penis of the savia paca*

^ 324^. Lastly, it deserves to be mentioned, that in some
species of this class, the male penis, while unerected, is turned
backwards, so that the urine is voided in the male in the same
direction as in the female. The hare, lion, and camel, afford
instances of this structure. But the statement which has been
so often repeated since the time of AristotlcjJ that these re-
tromingentia copulate backwards, is erroneous.

BIRDS.

§ 325. The testes, which lie near the kidneys, and the duc-
tus deferentes, are the only male organs which are constantly
found in the whole class.§

In a very few instances, as in the cock, the last mentioned
canals terminate in a dilated part, which has been considered
analogous to the vesiculas seminales. Instead of a penis, most
birds have in the cloaca two small papillae, on which the semi-

• Home, in the Philos. Trans. 1802, tab. 4, fig. I.

t Ibid. tab. 12, fig. 1.

% Historia Animalium, II. 1, V. 2 ; and De Partibus Animal. IV. 10.

$ G. G. Tannenberg, Spicilegium Observationum circa Partes Genitales J^asculas
Avium. Goetting. 1789-4.

ON THE MALE ORGANS OF GENERATION. 329

nal ducts terminate. This is the case in the cock, turkey, and
pigeon.

Some few species have a simple penis of considerable length,
which is ordinarily concealed and retracted within the cloaca ;
but remains visible externally for some time after copulation.
It forms a long worm-shaped tube in the drake,^ and consti-
tutes a groove in the ostrich, which is visible when the animal
discharges its urine.t

The testes of birds consist of a congeries of seminal tubes analo-
gous to those of the mammalia.

AMPHIBIA.

§ S26. The kidney, testes, and epididymis, lie close together
in the testudines, but each of the three organs may be distin-
guished, by its peculiar colour and structure, on the first view.
They appear to have no vesiculae seminales ; J I could at least
discover none in a testudo grceca which I lately dissected.
The penis, on the contrary, is very large, and retracted within
the cloaca in its ordinary state. Instead of an urethra, this
part contains a groove, whose margins approach to each other,
when the part is erected, so as to form a closed canal. This
may be compared with the groove-like continuation of the
cesophagv;s, which goes into the third stomach of ruminating
animals. The glans terminates in an obtuse hook-like point,
somewhat resembling the end of the elephant's trunk.

§ 327. Frogs ^ have large vesiculae seminales, and a small

* De Graaf De Mulierum Organis, tab. 17. Tannenberg, tab. 1 and 2.

Ibid. tab. 2 and 3 ; also Home, loc. citat. tab. 12, fig. 2.

t Cuvier, in the first part of the MSnagerie du Museum National.

f I should not express myself with uncertainty on this subject, if Lieberkuhn had
not ascribed vesiculae seminales to the turtle, (he does not mention the species) G.
E. Hamberger, Physiot. Med. p. 712.

There is much obscurity in the different descriptions of the male organs of gene»
ration of the turtle and tortoise. The various observations on this subject are col-
lected by Schneider, in his Natural History of the Genus Testudo, p. 129. See also
Gilibert, M^decin Naturaliste, 1st series. Lyons, 1800-8, p. 290; and Bojanus, in
the work above cited,

« Rösel, tab. 5, fig. 1, 2, and 3, tab. 6, fig. 1.

330 ON THE MALE ORGANS OF GENERATION,

papilla in the cloaca instead of a penis. Both these parts are
wanting in the toad.*

§ 328. Crocodiles have a simple penis, while the lizards of
this country (Germany) have two ; and the water-newt, which
does not copulate, has no organ of the kind.

§ 329. Serpents have long slender testicles, no vesiculae se-
minales, but a double penis, each of which has a bifid point
covered with sharp papillae.t

FISHES.

330. The male organs of generation possess very different
structures J in the different orders of this class. We shall
take two species as examples, the torpedo for the cartilaginous,
and the carp for the bony fishes.

• In the former instance there are manifest testicles, consist-
ing partly of innumerable glandular and granular bodies, and
partly of a substance like the soft roe of bony fishes. We
find also vasa deferentia, and a vesicula seminalis, which opens
into the rectum by means of a small papilla.§

The soft roe supplies the place of testes in the carp,|| and
most other bony fishes. It forms two elongated flat viscera of
a white colour, and irregular tuberculated surface : placed at
the sides of the intestines and swimming-bladder, so that the
left encloses the rectum in a kind of groove. Through the
middle of each soft roe passes a ductus deferens, which opens
behind into a kind of vesicula seminalis, and this terminates in
the cloaca. It is a curious circumstance that hermaphrodites,

* Ibid. tab. 21, fig. 25 and 26.

t Tyson, in the Philos. Trans, vol. xiii, tab. 1, fig. 2, in the rattlesnake, and fig. 3,
in the viper.

Franque De Serpentium quorundam Genitalibu^. Tubing. 1817.
' J Ph. Cavolini über die Erzeugung der Fische und der Krebse mit Anmerhmgm von
A. W. Zimmermann. Berlin, 1792, 8vo. in German.

De Graaf, Partium Genitalium Defensio, p. 253.

§ Lorenzini, tab. 4, fig. 4. See also Monro's Physiology of Fishes, tab. 11, 12.

II Petit, in the M4m. de I' Acad, des Sc. 1733, tab. 17.

ON THE MALE ORGANS OF GENERATION. 331

possessing the complete organs of both sexes, are found very
frequently in this species ; much oftener than among other
fishes.*

I possess the whole viscera of two such individuals, which
were found some years ago within a short time of each other.

INSECTS.

§ 331. The animals t of this class exhibit such numerous
varieties of structure in the different orders, genera, and spe-
ciesjj that we shall be contented with choosing two of the lat-
ter as examples. These are, the moth of the silk-worm, {bom"
hyx mori) which is chosen because its genital organs resem-^
ble those of some of the more perfect red-blooded animals ;
and a species of locust {gryllus) on account of the external re-
semblance between the male and female organs.

In the latter {gryllus verrucivorus) the large testicles, with
their convoluted fasciculi of vessels, bear a very close resem-
blance to the ovaries, in which the ova are collected into simi*
lar bundles. §

In the moth of the silk-worm we distinguish, besides the
testes, long vasa deferentia, even a kind of vesiculae seminales,
and a very considerable penis, with a hook-shaped glans.[|

* See Alischer, in the Breslau Collections, 14 vers. p. 645. Schawlbe, in the
Commerc. Lit. Noric. 1734, p. 305; and Morand, in the Hist, de I' Acad, des Sc.
1737, p. 51.

t See Henrich SchaefFer De gene^-atione Insectorum, partibusque ei inservientibus,
Ratisb. 1821.

i See a representation of these parts in the scardbmus nasicornis, by Swammer'^
dam, tab. 30 3 in a large water-beetle, tab. 22 ; in the nepa cinerea, tab. 3 ; in the
papilio urticce, tab. 36; in the ephemera hwaria, tab. 14; in the drone, tab. 21 and
22 ; in the musca cameleon, tab. 42 ; in the musca putris, 43.

In a cicada, Malpighi De Bombyce, tab. 11, fig. 2.

In a crab, Cavolini, tab. 2, fig. 10, 11. In the cancer Benhardus, Swammerdam,
tab. 11. In the crawfish, Rösel, vol. iii. tab. 60.

$ Rösel, vol. ii. tab. 9, of the locusts.

II Malpighi, tab. 10, fig. 1. Swammerdam, tab. 28, fig. 3:

332 ON THE MALE ORGANS OF GENERATION.

VERMES.

§ 332. From this class we shall select two instances.* The
one is an intestinal worm, (ascaris lumbricoides) and derives
therefore some interest from its connexion with nosology.
The cuttle-ßsh, of the class moUusca, forms the other, and is
selected on account of the remarkable peculiarities in its male
organs.

The ascaris has one testis, occupying nearly the middle of
the animal's body, and consisting of a single vessel convoluted
into a long bundle, but admitting of being unravelled with fa-
cility, when it appears to be about three feet in length. To-
wards the posterior part of the worm it forms a larger tube,
which nearly equals a crow's quill in size, and becomes con-
nected to the penis, which lies concealed near the tail, and is
probably projected at the time of copulation.-f*

Dr. Hooper states that he has never found any distinction of sex
in these worms, but that they all possess the parts described as be-
longing to the female.

See the account compiled by him in the Mem. of the Lond. Med.
Soc. vol. V. p. 237. Yet Dr. Baillie has given a figure of the male
worm, similar to that of Tyson, but it is copied from Werner. Fascic.
4, pi. 9, fig. 2 and 4. The representation of Cuvier agrees with that
of Dr. Hooper. Legons d'Anai. comp. torn. v. p. 187.

The male organs of the cuttle-fish {sepia loligo) have ex-
cited particular attention, from the remarkable, and indeed
somewhat heightened description which TurbervilleNeedham J
gave of them, and which formed the basis of Buffon's theory
of generation. §

* For the male organs of such vermes as have the generative parts of both sexes
combined in each individual, see Swammerdam, tab. 8, fig. 9, v?here they are repre-
sented in the slug.

For those of the aplysia, clio borealis, and tritonia. See Cuvier, loco citato.

Of the lepas balanus, Poli, vol. i. tab. 4, fig, 13.

Of the helix pomaiia, Swammerdam, tab. 5, fig. 10.

t Tyson, in the Philos. Trans, vol. xiii. p. 161, fig. 1.

X Nouvelles Observations Microscopiques, tab. 3 and 4.

§ Histoire Naturelle, torn. ii. p. 230,

ON THE MALE ORGANS OP GENERATION. 333

The part which corresponds to the soft roe of bony fishes,
contains at the spawning season several hundred small tubular
seminal receptacles (about four lines in length); these are
placed in bundles towards the vas deferens, and are contained
in a thick fluid. These tubes are expelled from the body in
an entire state, when a spiral vessel, which they contain, toge-
ther with the semen, as in a sheath, bursts their thin anterior
extremity, from which the semen escapes and impregnates the
spawn of the female.

334

CHAPTER XXIV.

ON THE FEMALE ORGANS OF GENERATION.

§ 333. An ovarium is the most essential and universal of all
the female parts of generation. In addition to this, those
animals vi^hich breathe by means of lungs, as well as some
fishes, and several white-blooded animals, have also oviducts
(Fallopian tubes, &;c.) or canals leading from the ovarium to
the uterus ; and lastly, those at least which are impregnated
by a real copulation, possess a vagina, or canal, connecting
the uterus to the external organs of generation.

In birds, all the parts which we have just mentioned are
single, excepting the ovaries, which in many birds are double.
Some cartilaginous fishes have two oviducts, beginning, how-
ever, by a common opening, and terminating in a simple ute-
rus. The human female, as well as that of many other mam-
malia, has two Ovaria, with an oviduct belonging to each, a
simple uterus, and vagina. The females of this class, in seve-
ral other instances, possess an uterus bicornis; and, in some
cases, the generative organs are double throughout ; that is,
there are two uteri, and, at least for some extent, a double va-
gina, as in the opossum. (Vid. Plate VII.)

Ovaria are found in the females of all animals where the male pos-
sesses testicles ; but their structure is in general more simple than
that of the latter glands, particularly in the first class. These bodies
were formerly called the female testicles, but the term ovary is much
preferable, as it denotes the function which the parts perform in the
animal economy. For, if the office of these bodies be at all dubious,
when their structure is considered in man and most of the mammalia,
their organization is so evident in the other classes, that no doubt
can be entertained respecting their physiology. It is manifest in all
these, that the ovaria serve for the growth and preservation of the

ON THE FEMALE ORGANS OF GENERATION. 335

germs, or ova, which exist in these bodies completely formed bfeforfe the
act of copulation. Analogy leads us to conclude that these bodies have
the same office in the mammalia, and thus our explanation and illus-
tration of this most interesting part of physiology are entirely derived
from researches in comparative anatomy.

MAMMALIA.

§ 334. Of the external female sexual organs in this class,
tlie clitoris is most generally found,* for it exists even in the
whales, + and probably is wanting in no other instance than the
ornithorhynchus.J

As this organ, in its general structure, bears considerable
resemblance to the male penis, it contains a small bone in se-
veral species of mammalia, as the marmota citillus, the racoon,
{ursus lotor) the lioness, the sea-otter, Sec. In the opossum
it possesses a bifid glans, like that of the penis. (Vid. Plate
VII.) The analogy between the two organs is carried so far
in the lori, {lemur iardigradus) that the urethra runs through
the organ and terminates on its anterior extremity. § In the
rat, the domestic mouse, the hamster, Sec. the clitoris and the
orifice of the urethra are placed at some distance from the
vagina, and in front of that part. This structure has some-
times been mistaken for a preternatural hermaphrodite for-
ma tion.||

In consequence of the horizontal position of the body of quadru-
peds, the clitoris is at the under-margin of the orifice of the vagina>
instead of the upper one, as in women.

* Linnaeus considered this organ to be a peculiar mark of distinction between the
human female and that of the simias ; whereas, in the latter animals, it is generally
remarkably large. I found it of very considerable magnitude in a mandrill, (jpapio
maimon) which I dissected.

t Tyson's Anat. of a Poi-poise, tab. 2, fig. 3.

In a balana hoops of fifty-two feet in length, this part was very large, even in pro-
portion to the monstrous size of the animal.

t Home, in the Vhil. Tram. 1802, p. 81,

§ Aubert, Hist. Nat. des Singes, tab. 2, fig. 8, of the anatomical figures,

II J. J. Döbel, in Nmj. Literar. Maris Balthici, 1698, p. 238.

Jo. Faber, in his remarks on F. Hernandez, Plantar. &c. Mejiravar, Histor. p.
547.

3S6 ON THE J-EMALE ORGANS OF GENERATION.

It is much larger iii the simiae than in women. The lemur, (macau-
co) the Carnivora, and most of the rodentia, have it also very large.

None of the mammalia possess nymphae ; and there is generally
merely a thin border of the integuments instead of labia pudendi.

§ SS5. A true hymen, or one at least, w^hich in form and
situation resembles that of the human subject, has been ob-
served in no other animal. The well-known membranous
valve, covering the orifice of the meatus urinarius in the va-
gina of the mare, can by no means be considered as a hymen.*

Cuvier considers the opening of the urethra as forming the dis-
tinction in quadrupeds between the vulva and the vagina ; now this
aperture is situated in many animals at a considerable distance with-
in the external opening of the genitals.

There is a contracted circle in this situation in the otter, dog, caty
and ruminating animals, which he considers as analogous to the
hymen. He mentions also the existence of a considerable fold in the
bear and hyena, in this situation ; and that he has found a manifest
hymen in the hyrax. According to the same author, the mare and
ass, and some of the simiae, have an analogous structure. Hence he
concludes, that the hymen is not a part exclusively peculiar to the
human species. Legons d'Anat. comp. torn. v. pp. 128, 133. It
appears, however, clearly from his own descriptions that the parts in
the above-mentioned animals only bear a remote resemblance to the
human hymen.

§ 336. The vagina of quadrupeds is distinguished from
that of the human subject by two chief characters : its direc-
tion, and the structure of its internal surface. In consequence
of the form and position of the pelvis, this canal lies in the
same axis with the uterus, or at least with the neck of that
organ. The glandular membrane, which constitutes its inter-
nal coat, forms none of those extremely elegant transverse
plaits, which distinguish it in the human female, but is merely
folded longitudinally. If transverse folds exist in any instance,

■* Ruini, p. 164. D?.ul)enton, tom. iv. tab. 4, fig. 2 j and tab. 8.

Bourgelat, loco citato, p. 383.

Brugnone, M6m. de I' Acad, des Sc. de Turin, tom. iv, p. 406.

The description of a similar part in the manati of Kamtschatka (fricAec/iMsmanafMs)
may be seen in the Npv, Comment. Acad. Petropolitan. tom. ii. p. 308 ; and on the-
hymen in animals consult Duvernoy, in the MSmoires presentes ä I' Institut, de France,
iScs, Physiques, tom. ii. p. 89.

ON THE FEMALE ORGANS OF GENERATION. 337

they are either confined to the immediate neighbourhood of
the external opening, as in the cow; or, if they extend farther,
as in the simice, they do not possess that regular arrangement
or beautiful formation which are displayed in the human
female.*

Dr. Gärtner of Copenhagen has recently called the attention of
anatomists to the existence of two canals in the vagina and uterus of
the covj, and some other mammalia. These canals commence in the
neighbourhood of the Fallopian tubes, and open into the vagina near
the meatus urinarius. They exist also in the soiv ; neither age nor
gestation makes any difference, they are always present. In the soio
these canals commence by two openings situated on the sides of the
orifice of the urethra, run obliquely from within outwards, in the
substance of the parietes of the vagina, and also a little upwards,
thus describing a curve. In this course they receive lateral branches
coming from the neighbouring glands, the union of which forms a
mass rather analogous in its external appearance to the pancreas ;
they diminish necessarily in size as they receive fewer of these small
lateral ducts, and especially in the part of the parietes of the vagina
which is continuous with the cornua of the uterus. They are always
present, but are found more developed a short time after conception.
In a sow, whose uterus contained some foetuses from two to three,
inches in length, the diameter of these canals was very consider-
able ; they extended even in the substance of the broad ligaments
to within a few inches from the ovaries, where they apparently ter-
minated in several small glandular bodies. The prolongation of these
canals into the broad ligaments was very evident ; their appear-
ance was white and opaque, but it was easy to inject them with
quicksilver ; in some points they were considerably, and appeared in
some others completely obliterated.

In the cow, the vaginal orifice of these canals is larger, situated
more in front, and on the side of the meatus urinarius ; these canals

• A representation of the vagina of tlie mare laid open, may be seen in Dauben-
ton, torn. iv. tab. 4, fig. 2.

That of the cow, in Nie. Hoboken, Anat. Secundiruz Vitulina. Ultraject. 1675,
8vo. fig. 3 ; and in J. G. Eberhard, Over het verlassen der Koeijen, Amsterdam,
1793, 8vo. tab. 1.

Of the ewe, Fab. ab Aquapendente, De formato Fatu, tab. 17, fig. 35 and 36 ;
and De Graaf, De MuUerum Organh, tab. 20.

Of the hind, Daubenton, torn. vi. tab. 17.

Of the rat, ibid, torn, vii. tab. 38, fig. 3.

Of the giinel, (^viverra genetta) ibid. torn. ix. tab. 37, fig. 2.

Of the panllier, ibid. tab. 16.

Z

338 ON THE FEMALE ORGANS OF GENERATION.

are continued the whole length of the lateral parietes of the vagina,
nearly to a level with the orifice of the uterus, where they appeared
all of a sudden to terminate. But an attentive examination shewed
that they penetrate into the cellular substance on the neck of the
womb, and re-appear on the body of the uterus, along which they
are continued to the cornua, and thence to within a short distance
from the ovaries. These canals are invariably to be found in the
course which we have just mentioned. In some young cows the ute-
rine portion of these canals is extremely fine ; in others, on the
contrary, it is somewhat dilated. The part of the canals correspond-
ing to the neck of the uterus is subject to several varieties, resulting
principally from the age and the gestation of the animal. See The.
Lancet, vol. ix. p. 273.

§ 337. The structure and form of the uterus vary very con-
siderably in this class. In no instance does it possess that
thickness, nor has its parenchyma that density and toughness
which are observed in the human female.* Of those which I
have dissected, the simia sylvanus had comparatively the firmest
uterus. The two-toed ant-eater came the next in order in this
respect. But in the greater number of mammalia this organ
is thin in its coats, resembling an intestine in appearance, and
provided with a true muscular covering.

§ 338. The variations in form of the impregnated uterus
may be reduced to the following heads :

1 . The simple uterus without horns {uterus simplex) which,
is generally of a pyramidal or oval figure. This is exemplified
in those animals where we have stated that it possesses thick
coats. Its circumference in some simice presents a more trian-
gular form than in the woman : and towards the upper part,
in the neighbourhood of the Fallopian tubes, there is an ob-
scure division into two blind sacst (as in the gibbon, or long-
armed ape) ; this distinction is more strongly expressed in the

* " Uterus humanus," (says Haller,) " ah omnium animalium uteris differt, quee
ego inciderim, Quadrupedum uterus vents est musculus, pene ut oesophagus. Crassior
etiam est in homine quam in ullo animale." Element. Physiol, torn. vii. pt, 2, p. 50.
" The human uterus is different from that of all animals which I have met with.
In quadrupeds this organ is a true muscle, something like the oesophagus. It is
thicker in man than in any animal."

t Daubenton, torn, xiv. tab. 6, fig. 2.

ON THE FEMALE ORGANS OF GENERATION. 339

lori, {lemur tardigradus) so as to form a manifest approach to
the uterus hicorms.*

2. A simple uterus with straight or convoluted horns {uterus
bicornis'). They are straight in the bitch,f in the racoon, in
the bats of this country, (Germany) in the sea-otter, seal, Scc.^
somewhat convoluted in the cetacea,% mare,\\ and hedgehog,
and still more tortuous in the bisulcaS

3. A double uterus, having the appearance of two horns,
which open separately into the vagina; this is seen in the
hare,** mole, and rabbilff (uterus duplex).

4. A double uterus, with extraordinary lateral convolutionSj
is met with in the opossum and kangaroo%'!\i {uterus anfractuo-
sus). Vid. Plate VII.

After I had dissected this curious part in a fresh opossum, I
began to understand the obscure and in part contradictory
descriptions given by others, and I trust that the plate (vii) at
the end of this volume will be found not only intelligible, as
compared with those by Tyson, Daubenton, and several others,
but sufficiently clear to give an idea of these parts to those
who may not have had the opportunity of dissecting them.

As the process of generation in these singular animals deviates
very considerably, in some of its parts, from the same function, as ob-
served in the other mammalia, a considerable difference is found in
the generative organs ; of which, as the subject is a very interesting
one, we shall present the reader with a more detailed description, as

• Ibid. tab. 31, fig. 4.

t Vesalius, p. 685, ed. of 1555.

% Daubenton, torn. ix. tab. 16, of the panther ; tab. 33, of the civet ; tab, 37, fig.
2, and tab. 38, 39, of the genet ; torn. xiii. tab. 51, of the seaZ.

$ Tyson, tab. 2, fig. 3.

11 La Fosse, tab. 45, 46.

5J It is represented in the sheep, by De Graaf, tab. 20.

In the cow, by Iloboken, fig. 29, 30 j by Eberhard, tab. I,

•• Daubenton, torn, vi. tab. 45.

tt De Graaf, tab. 25 ; Daubenton, loc. cit. tab. 56.

%t Home, in the Philos. Trans, for 1795, tab. l8, fig. 1 ; tab. 19, fig. 3 ; for
1808, p. 310; and 1810, pt. 2.

z 2

S4Ö ON THE i?EMALE ORGANS OF GENERATION.

well with reference to the male as to the female, from the 3rd vol. of
Sir. E. Home's Lectures on Comparative Anatomy.

With respect to the male organs of generation, Sir E. Home found
at the orifice of the prepuce, two delicately formed processes of a
very bright red colour ; the orifice of the urethra lay between them,
with a groove extending to the point of each ; they were half an
inch long, and bore an exact resemblance to the double tongue of the
snake.

From this mechanism it will be found, that in the act of copulation,
the double glans is not denuded till the penis has arrived at the end
of the vagina, being too delicate to bear the resistance of the more ex-
ternal parts.

The testicles are pendulous, hanging in a scrotum, with a narrow
neck, a little before the common opening of the anus and the passage
for the penis.

In the female, the organs of generation do not appear externally,
there being one common opening surrounded by cuticle covered
with hair ; for both the vagina and rectum, and the two canals, are
separated from one another, by means of a septum of no considerable
thickness.

The common orifice is projected beyond the bones of the pelvis
above two inches, and this prominent portion admits of considerable ^
piotion.

At the external orifice of the vagina is situated the clitoris, which,
when compared with the other parts, may be said to be large ; it is
inclosed in a preputium ; a little way further on in the vagina, are
two orifices, the openings of the ducts of Cowper's glands. The va-
gina itself is about an inch and a half in length, beyond which it leads
into two lateral canals ; and on the edge formed between them, openS
the meatus urinarius, leading to the urinary bladder.

These canals are extremely narrow for about a quarter of an inch
in length, and at this part their coats are very thick ; they afterwards
become more dilated and membranous ; they diverge in their course,
and pass upwards for nearly four inches in length ; they then bend
towards each other, so as to terminate laterally in the two angles of
the fundus of the uterus.

The uterus is extremely tliin and membranous in its coats, slightly
infundibular in its shape, and situated in the middle line between the
two canals.

In the virgin state it is impervious, so that at that time there
is no communication with the vagina, except by the lateral canals.

The same internal membrane that lines the lateral canals, appears
to line the uterus ; it is thrown into folds equally so in the uterus and
canals, and a broader fold than the rest marks a division of the uterus
into two equal parts.

The Ovaria and fimbriae resemble those of quadrupeds : the Fallo-
pian tubes follow nearly the same course to the uterus as in the
quadrupeds ; but a little way before they reach it they dilate consi-

ON THE FEMALE ORGANS OF GENERATION. 341

derably, forming an oval enlargement, the coats of which are much
thicker than those of the other parts, and the supply of blood« vessels
much greater, so that there is no doubt of its performing some pecu-
liar office ; beyond this part the tubes contract and pass perpendicularly
through the coats of the uterus at its fundus, and terminate in two
projecting orifices, one on each side of the middle ridge just men-
tioned.

The Ovaria in the kangaroo are similar to those of quadrupeds in
general, have corpora lutea produced in them, and in these the ova are
formed. When magnified four diameters, the appearance of the
structure of the corpus luteum is beautifully distinct.

From these examinations it would appear that commonly the kan-
garoo has only one young at a time \ for although in one ovarium
there are the rudiments of two corpora lutea, they are in different de-
grees of advancement.

It is evident that l)oth ovaria are forming corpora lutea at the same
time, but they are in very different stages.

As the ovum in this animal is not afterwards to be attached to the
uterus, there can be no doubt that the thickened oval portion of the
Fallopian tube, near its termination in the uterus, which extends to
the depending orifice, is to supply something analogous to yolk,
which is to attach itself to the ovum before it drops into the cavity ;
it is afterwards supplied by albumen from the internal surface of the
two lateral tubes ; in the same manner as albumen is formed in the
oviducts of birds.

The structure of the coats of the oval enlargement of the Fallopian
tube is of a very uncommon kind ; it does not resemble any known
gland in the body employed for secretion ; the yolk is oil or fat in a
most exceedingly concentrated state, which, according to Sir E. Home,
is formed in the intestine generally, but in some animals in the
liver ; and after being received into the circulation, is deposited by
the terminations of arteries whenever wanted. Nothing can better
accord with this idea, says Sir E. Home, than the apparatus set up
in the Fallopian tube ; there is an arterial trunk at some distance, of
considerable size, which sends off an infinite number of branches,
nearly of the same length, and all terminating in this oval portion of
the tube. This is perhaps the only structure to be met with of the
kind, probably also the only occasion in which concentrated oil is re-
quired to be suddenly collected.

When the ovum arrives at the uterus, it is enveloped in an abund-
ant quantity of albumen. There was nothing like shell, and the soft
ovum had been too long preserved in spirit to retain its natural ap-
pearance, it was reduced to a pulp. The uterus and the lateral tubes
were filled with this jelly, and the os tincae plugged up with it; the
lateral tubes were open into the vagina. In the cavity of the uterus,
in the midst of this coagulated jelly, was a small portion of the rudi-
ments of a foetus.

The mode in which impregnation takes place has not been satis.-

S4<2 ON THE FEMALE ORGANS OF GENERATION.

factorily explained ; but Sir E. Home has now no doubt that the
semen is conveyed into the uterus through the two lateral canals, and
is there applied to the albumen in which the molecule corresponding
to the human ovum is enveloped, and the embryo is afterwards
aerated by means of the atmosphere through the openings into the
lateral canals from the vagina.

How long it requires for the ovum to be hatched in utero, is not
even at this day ascertained ; whenever that happens, the young is
propelled into the marsupium through the os tincse which opens
for that purpose. There it becomes attached to the point of the
nipple.

The mammae are two in number ; each of them has two nipples ;
they are not placed upon the abdominal muscles, as in other quadru-
peds, but are situated between two moveable bones connected to the
OS pubis, and the mammse are supported upon a pair of muscles
which arise from these bones, and unite in the middle between them.

These mammse are covered anteriorly by the lining of the false
belly, and the nipples project into that cavity ; this covering is simi-
lar to the external skin, having a cuticle, and short hair thinly scat-
tered over its surface, except at the root of the nipples, where there
are tufts of some length, one at the basis of each.

The mammse are supplied with blood from the epigastric arteries.
The mammary branches run superficially under the false belly till
they reach the mammse. There is a strong muscle which connes
down from the upper part of the abdominal muscles, and adheres
firmly to each of the mammse ; this prevents the gland from being
dragged from its natural situation while the young is suckling.

The two bones that lie behind the mammse deserve a particular
description, as they are met with in the whole tribe that have false
bellies, and are not even peculiar to them, in some degree belonging
to other animals, as the crocodile ; they go to the mammse, and
have no other use but what is connected with the motion of these
parts.

Tliey are about two inches and a half long, are flattened, and at
their broadest part measure nearly half an inch ; they are attached to
the projecting part of the os pubis, which is fitted for that purpose,
just before the insertion of the recti muscles ; this attachment to the
pubis is by a very small surface, and admits of considerable motion.
They have likewise a connexion by a ligament half an inch in breadth,
to the ramus of the pubis which joins the ileum. From their base,
which is united to the pubis, they become narrower till they termi-
nate in a blunted point. These bones have a pair of muscles inserted
into their base, to bring them downwards and outwards ; another
pair is connected to their blunted extremities to bring them forwards ;
a pair of broad flat muscles fills up the whole space between them,
arising from their inner edge through its whole length ; these last
serve as a sling to support the maramee, and also to bring the bones
towards each other.

ON THE FEMALE ORGANS OF GENERATION. 343

Besides these additional bones, and the projection to which they are
attached, there is another pecuUarity in the structure of the pelvis of
the female ; the two rami of theos ischium which join the pubis, have
no notch between them, as in other quadrupeds, but form a round
convex surface of some bi-eadth, projecting considerably forwards.
The surface itself is smooth, like those over which tendons pass ; but
the lateral parts are rough, and have a pair of muscles arising from
them, inserted into the skin of the false belly, to bring its mouth to-
wards the pudendum.

The mode in which the young passes from the uterus into the false
belly, has been matter of much speculation ; and it has even beert
supposed that there was an internal communication between these ca-
vities. This idea took its rise from there being no visible opening,
between the uterus and vagina during impregnation ; but such an
opening remaining of some size after parturition, explains the mode
in which the young passes out ; and the false belly or bag having
muscles, which must, when they are in action, bring both the orifice
and the mammae themselves close to the vulva, removes all theoreti-
cal objections against the young getting to the nipple ; particularly as
the vulva has naturally an unusual projection, and the margin of the
pelvis immediately before it is rounded and smooth, so to admit of its
moving easily in that direction. The very action of opening the
mouth of the false belly, by bringing down the skin, will allow the
external orifice of the vagina to be thrown still further out, so as to
project more directly over the mouth of the false belly in which the
foetus is to be deposited.

It is to be observed, that as all these circumstances belong to the
parts in a natural state, they will be much increased at the period at
which parturition takes place, since in all animals at that particular
time, there are changes going on to facilitate the expulsion of the
young in the way most favourable for its preservation. The size of
the young at this period is not exactly known.

When the yovmg is first attached to the nipple, the face appears to
be wanting, except a round hole at the muzzle to which the nipple is
applied and adheres ; soon after, the lips and jaws grow upon the
nipple, till at last nearly half an inch of its length is enclosed in the
mouth.

The kangaroo has only one young at a time, which may be seen
attached by the mouth to the nipple inside the mother's pouch, from
the period it is the size of your thumb-top, and as unshapely as
a new-born mouse, until it attains the size of a poodle-dog, with
a fine glossy coat of hair, ready to leap out and hop along after the
mother. The young are attached by the mouth to the nipple in
somewhat the same way as the placenta of other animals is at-
taclied to the uterus, the mouth bein^^ contracted round the nipple,
which swells out like a cherry inside it, nourishing the foetus by way
of absorption through this indirect channel, the mouth and nipple ad-
hering so strongly, that it requires considerable force to separate

344' ON THE FEMALE ORGANS OF GENERATION.

them. When the foetus arrives at sufficient age to suck, it drops off
the nipple, and may then be said to be born, yet still continuing in^^
side of the pouch, and sucking milk now through the ducts ofthat same
nipple, from the external surface of which it formerly derived a very
different species of nourishment. The manner in which the young
reach this pouch from the ovary, and attach themselves to the nipple,
is still a mystery, as no communicating duct has yet been found ; but
the natives assert they are born in the usual way, and that the
mother places them there. It is amusing to see the young kangaroo
pop its head out of the pouch, when the mother is grazing, and nib-
ble, too, at the tender herbage which she is passing over. When hard
hunted, the mother will stop suddenly, thrust her fore-paws into her
pouch, drag out the young one, and throw it away, that she may hop
lighter along. Tliey are always very hard pressed, however, before
they thus sacrifice the life of their offspring to save their own ; and
it is pitiful to see the tender sympathetic looks they will sometimes
cast back at the poor little helpless creature they have been forced to
desert. From this singular mode of gestation, you may handle the
foetus in utero, and pull it about by the tail like a kitten, from the
first moment of its appearance there, up to the very day of its birth,
without causing either pain or annoyance to it or its mother. Such
is the very singular manner in which nearly all our Australian quad-
rupeds are generated and brought forth. When the young kangaroo
has attained a considerable size, it will crawl out, feed about, and
creep in again to warm itself, or in case any danger approaches.
The kangaroos feed early in the morning when the dew is on the
grass, which is the best time to hunt them. See Cunningham's Two
Years' Residence in New South Wales. London, 1827.

Externally there is no appearance of organs either in the male or
female ornithorhynchus, the orifice of the anus being common to the
rectum and penis in the male, and to the rectum and vagina in the
female. After the most careful search, says Sir E. Home, there was,
not the slightest appearance of nipple. The male is distinguished
from the female by no other external appearance than the spur, which
is attached to the heels of both the hind feet ; it is half an inch in
length, with a sharp point. There is a joint between the spur and the
heel, admitting of motion in two directions, one that brings it in to-
wards the body, in which state it lies concealed ; the other throws it
onwards, and renders it very conspicuous.

These spurs, Sir John Jameson, resident in New South Wales, who
has the opportunity of examining the parts in a recent state, declared
to be tubular, and gave to the Linnsean Society a paper on that subject
sonie years ago ; he also mentioned that some of the natives, who
had been wounded by them, asserted that they emitted a liquor of a
poisonous nature. In examining the parts, after being long kept in
spirits, no such structure was met with ; and when the spurs were
boiled, the cavity appeared to be similar to that of tlie cock, only
filled with a pulp instead of a core ; this, however, Sir E. Home has

ON THE FEMALE ORGANS OF GENERATION. S45

since discovered to be an artificial appearance, the effect of coagula-
tion. Upon examining the spur in a better state of preservation. Sir
E. Home not only found a membranous tube passing through the
spur, which has an orifice on one side, near the point ; but Mr. Clift
succeeded in injecting a duct leading to a gland which lies across the
back part of the thigh, over the muscles, one inch and more in length,
and half an inch broad ; the excretory duct passes like the ureter of
the kidney out of one side, near the middle. The quicksilver inject-
ed immediately pervaded every part of the gland ; and when the
point of the pipe was turned downwards, ran readily to the root of
the spur, where the duct made a turn, and formed a small reservoir.
After a little time, however, the mucus being gently squeezed and
pressed forward, we saw the mercury in the spur, and at last it came
out of the orifice.

A secretion is emitted through the spur of the male into this
socket, and the parts are so minute as to require glasses of consider-
able power. Mr. Bauer examined the socket in the female, and after
overcoming considerable difficulties, the parts being very much cor-
rugated, and yet retaining their elasticity, he made out the form of
this socket, which corresponds exactly in shape with the spur itself,
so that when completely introduced, it must be so grasped that the
male would be unable to withdraw it when the coitus was over, iri
this respect resembling the effect of suction.

The testicles are situated in the cavity in the abdomen, immedi-
ately below the kidneys ; they are large for the size of the animal.
The epididymis is connected to the body of the testicle by a broad
membrane, which admits of its lying very loose. The penis of the
male has a structure of a very extraordinary nature. The urine does
not pass along the urethra of the penis ; it is conducted by a distinct
canal, which opens into the rectum, an inch above the external orifice
of that gut. On each side at this part is a large solid body, the size
of a testicle, which proves to be a gland ; each of these has a small
excretory duct, which passes to the root of the penis, where they
unite, and then open by one common orifice into the seminal urethra,
one tenth of an inch after it has entered the penis.

These glands must be considered to correspond with Cowper's
glands in the human body, and not as either a substitute for pros-
tate gland or vesiculse seminales, since they are met with in the fe-
male.

In the female they are smaller than in the male. Their ducts open
by one common aperture on the posterior surface of the vagina, one-
fourth of an inch within the orifice ofthat canal.

The penis, which is solely appropriated for the passage of the
semen is very short, when in a relaxed state, nor is it capable of
being much elongated, when erection takes place. The prepuce is a
fold of the internal membrane of the verge of the anus, as in the
birds, and the penis when retracted is entirely concealed.

The urethra leads directly from the bladder to the rectum ; near

346 ON THE FEMALE ORGANS OF GENERATION.

the double glands it divides into two, one going to each ; and instead
of there being a single external orifice, as is usual in other animals,
one terminates in five small prominent papillae, the other in four ;
they take different directions, corresponding to the tw® openings of
the uterus of the female ; the urethra swells out into a cavity in the
centre of each glans, and thence communicates with all the papillae,
whose orifices are the size of hairs. When water is injected through
the urethra, the mode in which it is scattered by the nine orifices of
the papillae, exactly resembles the pouring water out of a watering
pot.

The vasa deferentia open into the membranous part of the urethra
before it reaches the penis.

The female organs open into the rectum as in birds ; just within
the anus there is a valvular projection between the rectum and va-
gina ; it is slender, half an inch long, bifid at the point, and enclosed
in a prepuce, the end of the glans only projecting into the vestibu-
lum. The vagina is about one inch and a half long, its internal mem-
brane rugous, the rugae being in a longitudinal direction ; at the end
of the vagina is the meatus urinarius, and on its two sides are the
openings leading to the utera. This corresponds as nearly as can be
to the kangaroo and the opossu?n, only in this animal the uterus in the
middle of the vagina is wanting, and on each side, in place of the la-
teral canals, there are two uteri in form approaching to the oviducts of
birds. At the end of each uterus there is a small ovarium covered by
a capsule.

When the ovarium was examined by Mr. Bauer, it was found to
be filled with yolk bags, less deeply imbedded in its substance than
those of the American opossum, bearing a greater resemblance to
the yolk bags of the fowl ; and to make this resemblance more intel-
ligible they were compared together ; the great difference between
them is, the covering of the ovarium in this animal being strong and
opaque, while there is no such outer coat in the fowl, and the
clutch of yolk-bags is double in the ornithorhynclii, and single in the
birds.

There is an approach to this in the bird, in which there is only one
ovarium and one oviduct ; but in the chick of the common fowl, be-
fore it is hatched, there is a small portion of an incipient oviduct on
the right side ; but this disappears before the chick is completely
formed.

As the ornithorhynchus paradoxus resembles the opossum tribe in hav-
ing a vagina and a penis, these animals copulate exactly like the
quadruped, which made it difficult to understand where the ovum was
brought to perfection. The uteri appeared not to be convenient si-
tuations ; and yet, if not there, the position of the meatus urinarius
seemed to preclude an ovum from having a shell formed in the va-
gina or cloacus, at the rectum, a necessary protection before it could
be laid externally.

The second series oi ornithorhynchus we have called hystrix; how-

ON THE FEMALE ORGANS OF GENERATION. 347

ever much it differs from the other in its external appearances
and habits, it resembles it nearly in the organs of generation ; it
is an inhabitant of New South Wales. One of this species was
shot in Endeavour Bay, by Van Dieraen's land ; it was seventeen
inches long, and when it walked, the body was two inches from the
ground.

The animal which Sir E. Home examined was a male ; externally
there was no appearance of organs of generation, in this respect
being exactly similar to the paradoxus. Just at the setting on of the
heel the hind legs had the same spur already described in the other
species ; there was also a gland on the posterior part on the thigh,
and a duct leading from it to the spur, but smaller than in the para-
doxus.

The male organs resemble those of the paradoxus in the form and
situation of the testicles, the opening of the vasa deferentia, and the
opening of the urinary uretln-a into the rectum, as well as that of the
seminal urethra, which runs in the middle line of the penis.

The penis is very elastic in its substance : when drawn out is about
three inches long ; in a natural state, before it was hardened in spi-
rit, it of course could be farther extended. The glans is divided into
four portions of equal length, two facing to the right, and two to the
left, so that there are evidently two adapted to each uterus. All these
have an orifice in their centre, surrounded by concentric circles of in-
finitely small prominent papillae.

The female organs Sir E. Home has not seen, but the correspond-
ence there is between those of the male in the two diflferent kinds, im-
plies a similarity in those of the female.

The hystrix in many parts of its form is a nearer approach to
the more perfect quadrupeds than the paradoxus ; and as its tongue
is in some respects like those of the manis and myrmecophaga, it was
natural to look among the different species of these genera for other
points of resemblance.

§ 339. These various forms undergo different changes in
the pregnant state.

The alteration in the simple uterus is, on the whole, analo-
gous to that which occurs in the human female.

The pregnant uterus bicornis suffers a different change in
those animals, which bear only one at a time, from that which
it undergoes in the tnuliipara. The foetus of the mare is con-
fined in its situation to the proper uterus.* In the cow it ex-
tends at the same time into one of the horns, which is enlarg-

Ruini, p. 181 et seq. Fab. ab Aquapendente, tab. 20, 21.

348 ON THE FEMALE ORGANS OF GENERATION*

ed for its reception.* In those, on the contrary, which brings
forth many young at once, as also in the double uterus of the
hare and rabbit, both cornua are divided by contracted por-
tions into a number of pouches corresponding to that of the
young ; and where those horns are straight in the unimpregnat*
ed state, as in the bitch, they become convoluted. t

The uterus anfractuosus of the marsupial animals under-
goes the least change from its usual appearance in the impreg-
nated state. For these strange animals bring their young into
the world so disproportionately small, that they appear like
early abortions.

§ 340. The Fallopian tubes are convoluted upon each other
in a kind of knob in some instances, as the simia sylvanus, and
still more remarkably in the opossum. Theßmbrice are some-
times shaped like a funnel, as in the rabbit.

§ 341. The ot^ana are generally of an oval form, and have
the ovula Graafiana buried in their parenchyma. These vesi-
cles, however, project externally in some cases, as in the pig ;
where the ovaries appear tuberculated on the surface. J In the
hedgehog they are quite loose and separate, so that the ovary
resembles a bunch of grapes, and thereby approaches to the
structure of the bird.

The number of vesicles appears to accord on the whole with
that of the young which a mother is capable of producing
during her life.§

The wild and domesticated races of the same species of ani-
mals differ very remarkably in their fertility : which difference
furnishes a new and strong argument against the supposed
pre-existence of previously formed germs in the female ovary.
The domestic sow brings forth commonly two litters in the

* Hoboken, fig. 1, 6, 31. Eberhard, tab. 9, 10.

t Fab. ab Aquapendente, tab. 28, of the hitch.

Id. tab. 24, of the pig ; also Daubenton, torn. v. tab. 20.

Id. tab. 29, of the tnouse.

Id, tab. 30, of the guinea-pig.

t Wrisberg, in the Comment. Soc. Reg. Sclent, G'detting, torn. iv. p. 69.

§ Hunter, in the Philos. Trans, vol. Ixxvii. p. 233.

ON THE FEMALE ORGANS OF GENERATION. 349

year, each of which consists, perhaps, of twenty young ones.
The wild animal, on the contrary, becomes pregnant only once
in the year, and the number of its young never exceeds ten.
Both reach about the same age, viz. twenty years.

A similar difference is found to obtain between the tame and
wild cats ; as also between the domestic dove and the wood-
pigeon. How should those domestic animals, which descend
from the original wild stock, produce such a remarkably
greater number of young ones, if these are merely to be
evolved from germs, which have existed since the first crea-
tion of things ?

And the corpora luteal which have received this name
from their colour in the ovaries of the cow, are probably never
found in the quadruped, except after impregnation.

I have shewn in the Comment, Soc, Goetting, tom.ix. p. 109,
that corpora lutea may be formed in the ovaria of virgins, as
empty calices axe sometimes met with in those of birds which
have not copulated ; and have also pointed out under what
circumstances this takes place.i*

BIRDS.

§ 342. The female organs of generation in this class may
be most conveniently arranged under three divisions : the ex-
ternal parts including the cloaca ; the tubus genitalis (oviduct)
resembling an intestine ; and lastly the ovarium, which is al-
most entirely separate from the latter part.

As the general structure of these parts is very uniform in all
birds, we may take as an example the most familiarly known
species, the hen.%

§ 343. The external opening of the genitals consists of a

• Vide Sir E. Home, in the PhU, Tram, for 1819, p. 59, with excellent plates of
these parts in the cow and sow,

t G. Spangenberg, Disquisitio circa partes genitales famineas Avium. Goett. 1813.

t For the sake of brevity, I refer once for all in tiiis description of the generative
organs of birds, to the excellent delineations by Ulmus, in Aldrovandi's OrniOiolog,
torn. ii. p. 209, ed. of 1G37 ; and by De Graaf, tab. 18 ; and to Spangenberg's work.

S50 ON THE i?EMALE ORGANS OP GENERATION.

transverse slit behind the ossa pubis, which do not form a
symphysis ; this is larger in the hen than in the cock ; and its
smaller anterior labium is covered by the larger posterior one
{velahrum).

This slit leads to the cloaca, in which several organs open,
{% 114). These are the rectum; the two ureters on the pro-
minent margin of that part ; the vagina on the left ; behind
which, and on the upper part of the cloaca, there is the bursa
Fabricii.

The opinion of the celebrated anatomist, whose name this
mysterious organ bears ; that it receives and retains the semen
of the cocJc, is refuted by this circumstance among many
others, viz. that the part in question is found also in the cocJc^
where it is actually much larger than in the hen ; nay, it is often
so small in the latter, that its very existence has lately been
denied. This however is going too far« For 1 have never
failed in finding it, at least in young Jiens, although it is
sometimes no longer than a barley-corn, and instead of being
loose, as in the cocJc, is closely invested by cellular substance,
so that its demonstration requires some care and attention.
The opening, by which it may be inflated, is found on the su-
perior surface of the cloaca, behind the termination of the rec-
tum, and on the front edge of a small eminence {scutellum) the
size and development of which seem to be in an inverse ratio to
those of the bursa.

From all the observations which I have been able to make
on this part (which Perrault very inappropriately termed le
troisieme ccecum) I am led to conclude, that the function,
which forms its final use, must belong to the male, and that it
is only to be considered as a mechanical rudiment in the hen,
thereby affording another example of the union of the two
principles in the formative impulse.

In the present instance the teleogical principle is manifest-
ed in the bursa of the cock, and the mechanical in that of the
hen. In the breasts, on the contrary, the-case is reversed ; the
teleogical principle prevails in the female sex, where the final
use or purpose of the glands is discerned ; and these parts are

ON THE FEMALE ORGANS OF GENERATION, 351

formed in the male, merely as rudiments, in compliance with
the mechanical principle.

§ 344. In the tubus genitalis, which considerably resembles
an intestine, and is really on the whole very uniform in its ap-
pearance, we may however distinguish three parts. The va-
gina, the proper uterus, and the oviductus ; the latter part
terminates in the infundibulum, which is very different in its
structure and appearance.

The vagina is about one inch and a half long, and very
extensile : it follows a tortuous course.

The uterus is about the same length, but larger and thicker
in its parietes, and folded internally.

The oviductus (in French la portiere) appears like a conti-
nuation of the last mentioned part ; it is about one foot and a
half long, convoluted like an intestine, and though slightly
contracted at intervals, on the whole conical, so that it de-r
creases in diameter to the infundibulum. Its internal coat is
covered with innumerable papillae, which secrete the white of
the egg ; and the whole tube is connected above to the spine
by a kind of mesentery (mesometrium or meserccon uteri).

It opens by its small end into the infundibulum, which is an
expanded part, analogous to the fimbriated extremity of the
Fallopian tube, for receiving the yolk from the ovarium.
This infundibulum is formed of a delicate membrane, with a
very elegantly folded margin, which is connected behind to
the uterus by means of a round tendinous cord.*

In speaking of the uterus and vagina of birds, the author does not
sufficiently keep up the distinction which ought to be observed be-
tween an uterus and an oviduct.

The germ, or ovum, passes from the ovarium through a canal,
which either conveys it out of the body, (as in the case of the egg)
or transmits it into another organ. The latter is a cavity, admitting
of enlargement, and having the germ attached to its parietes by
means of vessels, which nourish and preserve it until it has acquired
a certain development.

The first mentioned organs are found in all the four classes of

* Two oviducts have been sometimes discovered in hens. Vide Stenonis, in 2nd
vol. of the AU. liavn.^, 226; and Morgagai's Eyist. Anat. XX, note 31.

35^ ON THE FEMALE ORGANS OF GENERATION.

vertebral animals : they are called Fallopian tubes in the mammalia,
and oviducts in the three other classes. The latter belongs to the
mammalia only, and is their uterus. We find, however, that the
author speaks of the uterus of other classes : the difference in the
office of the parts is so striking that they should on no account be
confounded together.

§ 345. The ovarium, resembling in its appearance a bunch
of grapes, lies under the liver, and contains in a young laying
hen about five hundred yolks, varying in size from a pin's
head to their perfect magnitude ; the largest alveays occupy
the external circumference of the part. Each yolk is inclosed
in a membrane {calyx) which is joined to the ovarium by
means of a short stalk or pedicle (petiolus). A white shining
line forms on the calyx when the yolk has attained its com-
plete magnitude. The membrane bursting in this part, the
contained yolk escapes, and is taken up by the infundibulum
in a manner which we cannot easily conceive.* It then passes
along the oviduct, and acquires in its passage the white and
shell.'f The calyx, on the contrary, remains connected to the
ovarium ; but it contracts and diminishes in size, so that in
old hens which have done laying, the whole internal organs of
generation nearly disappear. This forms one of the many
instances in the animal economy of remarkable and peculiar
motions, which cannot be referred to any of the general vital
and motive powers, as contractility, irritability, &c. accord-
ing to the physiological notions which have been hitherto
affixed to those terms. Hence I have arranged them as spe-
cimens of a peculiar principle, or vita propria, without pre-
suming to give any explanation of the subject. This term
will serve to denote and distinguish them until the received
opinions on the above-mentioned general vital powers shall
have been so far altered or modified as to include these pecu-
liar cases.J

* Wepfer, Cicutee Aquaticce Historia et Noxa, p. 173.

t Vide Dutrochet, in the Journal de Physique, torn. Ixxxviii.

X I have entered more fully into this subject in my Cura iterates de vi vitali canguini
deneganda, vita autem propria solidis quibusdam Corporis Humani partibus adserenda.
Goettingen, 1795, 4to.

ON THE FEMALE ORGANS OF GENERATION. 353

AMPHIBIA.

§ 346. The tortoise has a manifest ditoris, lying in the clo-
aca. The uterus, oviduct, and ovarium, have on the whole
much analogy with those of birds ; but all these parts are
double, and have two openings into the cloaca.* The two
uteri are thick and fleshy, while the oviducts are thin and
delicate.

§ 347. The frogs of this country (Germany) have a large
uterus, divided by an internal partition into two cavities, from
which two long convoluted oviducts arise and terminate by open
orifices at the sides of the heart. The Ovaria lie under the
liver, so that it is difficult to conceive how the ova get into the
above-mentioned openings. The uterus opens into the cloaca.t

The toads have not the large uterus ; but their oviducts
terminate by a common tube in the cloaca. J

§ 348. The lizards of this country (Germany) have on the
whole a similar structure to that of the last-mentioned animals.
Their oviducts are larger, but shorter, and the ovaria contain
fewer ova.

^ 349. Female serpents have double external openings of
the genitals for the reception of the double organs of the
male. The oviducts are long and much convoluted. The
ovaria resemble rows of beads, composed of yellow vesicles.

PISHES.

^ 350. We shall take the torpedo and the carp as exam-
ples of the two chief divisions of the class, as we did in
speaking of the male organs. §

' * Caldesi, tab. 6, fig. 9, 10.
t Rose], tab. 4, fig. 2, tab. 7, 8.
t Ibid. tab. 21, fig. 24.

The structure is the same in the rarm pipa (Surinam toad). See Camper's Kleinere
Schriften, vol. i. pt. 1, tab. 3, fig. 1.
§ Cavolini, loco citato.

2 A

354 ON THE FEMALE ORGANS OF GENERATION.

In the former fish* there are two uteri, communicating with
the cloaca by means of a common vagina. The oviducts form
one infundibulum, which receives the ova as they successively
arrive at maturity. These are very large in comparison with
those of the bony fishes. The yolk, in its passage through
the oviduct, acquires its albumen and shell. The latter is of
a horny consistence, and is known by the name of the sea-
mouse.t It has an elongated quadrangular figure, and its
four corners are curved and pointed in the skate, while they
form horny plaited eminences in the sharJcs.X The secretion
of the albumen, and the formation of the shell are performed
by the papillous internal surface of the duct ; and chiefly by
two glandular swelHngs which appear towards its anterior ex-
tremity in the summer months while the eggs are being laid).§

The structure is much more simple in the carp, and pro-
bably also in the other oviparous bony fishes. The two roes
occupy the same position as the soft roe of the male does.
They are placed at the side of the intestines, liver, and swim-
ming bladder, as far as the anus. They consist of a delicate
membrane inclosing the ova, which are all of one size, and
extremely numerous (more than 200,000 in the carp) ; and
terminate by a common opening behind the anus.|l

The Ovaria of fishes generally contain a very large number of ova,
so as to account to us satisfactorily for the astonishing multitudes in
which some species are formed. In a perch, weighing one pound, two
ounces, there were 69,216 ova in the ovarium ; in a mackarel of one
pound, three ounces, 129,200; in a carp of eighteen inches, Petit
found 342,144 ; and in a sturgeon of one hundred and sixty pounds,
there was the enormous number of 1,467,500.

* Lorenzini, tab. 3, fig. 1, 2 ; also Monro's Physiology of Fishes, tab. 2 and 13
of the skate.

t W. G. Tilesius über die so genannten Seemäuse oder hornartigen Fischeger.
Leipzig. 1802, 4to. tab. 4, 5.

i J. Hermann, Tabula Affinitatum Animalium, p. 279.

§ These temporary organs were known to Aristotle, who called them breasts. See
also Rondelet De Piscibus Marinis, p. 380, Collins, vol. ii. tab. 43. Monro and
Tilesius, loc. citat.

11 Petit, loc. citat.

ON THE FEMALE ORGANS OF GENERATION. 355

INSECTS.

§ 351. We shall here notice the two species only which
were mentioned in the former chapter.*

Each of the large ovaria of the gryllus verrucivorus contains
about fifty ova disposed in bundles. The two organs are
connected together at their posterior extremities, and open
between the two sheaths of a part by which they are dis-
charged from the body.t

In the silkworm moth,"^ on the contrary, the ovarium re-
sembles four rows of pearls ; each row contains about sixty
ova, which are laid from the end of the abdomen, after passing
through a short duct, which has, however, connected with it
several vesicular processes of uncertain use.

VERMES.

§ 352. We shall describe here the female genitals of those
two animals only, whose male organs were noticed in the pre-
ceding chapter. §

The opening of the genitals of the female round-worm {as-
caris lumbricoides) is situated near the middle of the body,
and leads to a short canal, which divides into two tubes.
These gradually contract into two slender, thread-like ovi-
ducts, which are very long and variously convoluted. || It
happens occasionally that the integuments of the worm burst,
and some turns of the duct protrude : these have been mis-
taken for young worms, and have given rise to the erroneous
notion that the animal is viviparous.

* In the works quoted at page 33 1 , delineations of the female organs of generat
tion of the insects tliere mentioned will be found.

t Rösel, loc. citat. tab. 9, fig. 3.

t Malpighi, tab. 12, fig. 1, 2,

$ For an account of these parts in some other genera, see the works quoted in
note 15, § 329.

II Tyson, in the Pkilos. Trans, vol. xiii, fig. 2, or in his works. London, 4to.
1751.

(The same parts have also been represented by Dr. Hooper, in tlie Memoirs of the
London Medical Society, vol. v. ; and by Dr. Baillie, in his elegant Fasciculi of
Morbid Anatomy, fascic. 4, pi. 9, fig. 3 and 5, T.)

2 A 2

356 ON THE FEMALE ORGANS OF GENERATION.

The structure of the parts is very simple in the cuttle-ßsh.
There are two ovaria, containing ova of various sizes, and a
common tube leading to the anus.*

The genital tubes of the ascaris contain a milky fluid, which, when
examined by the microscope, is found to contain numerous ova.

The ascaris vernicularis possesses a genital apparatus of the same
appearance with that of the lumbricoides. Dr. Hooper in Trans, of
the Lond. Med. Soc.

The ova of the cuttle-fish, when discharged from the body, are
connected into bunches, exactly resembling grapes, by a tenacious
and ductile substance. The similarity is so striking as to have given
rise to the term of sea-grapes, which is applied to them in common
language. In the sepia octopus and loligo (calmar) they form small
masses.

Most of the gasteropodous mollusca are true hermaphrodites, and
have the male and female organs of generation united in the same
individual ; but they copulate, so that each fecundates and is fecun-
dated. The common slug {Untax) and snail (helix) afford the most
familiar examples of this structure. They possess an ovarium, ovi-
duct, testis, vas deferens, and penis. The oviduct and vas deferens
open into a cavity situated under the right superior horn ; and the
penis is contained in the same cavity. The latter part enters the
oviduct of the other animal at the time of copulation.

The snail has, in addition to these organs, a very singular one, the
VLse of which is quite obscure. It consists of a cavity with an emi-
nence at bottom, from which a sharp pointed, thin, calcareous body
proceeds. This can be thrust forth from the cavity, and is employed
by the snails to prick each other before the act of copulation.

In the acephalous mollusca, such as the oyster, muscle, &c. there
is no discernible organ of generation, except an ovarium, which
varies in size and colour at different periods of gestation.

The same observation holds good also of the asterias (star-fish)
and echinus (sea-urchin). In both these genera the ovaria consist of
several distinct masses of ova.

The process of generation in the zoophytes resembles the growth
of buds and branches in trees, and therefore these animals contain no
generative organs, nor have any distinction of sex. This is the case
in the polype (hydra) and the sea anemone, (actinia) where the young
shoot out from any part of the surface of the parent. If these animals
are cut in two, the divided portions will form perfect animals.

* Turb. Needham, Nouvelles Obs. Microsc. tab. 2.

Compare with this the delineations by Lister, which indeed are somewhat diffe-
rent. Conchylior. bivalv. exercit. Anat: Tertia. Lend. 1696, 4to. tab. 1, fig. 10 j
and by Swainmerdam, tab. 52, fig. 10.

357

CHAPTER XXV.

ON THE FCETUS OF THE MAMMALIA, AND THE ORGANS WITH
WHICH IT IS CONNECTED.*

§ 353. The first parts which can be discerned in the uterus
after impregnation, are the membranes (involucra) of the
ovum ; in which (the marsupial animals excepted) the embryo
itself becomes visible after a certain period. By means of
the navel-string the foetus is connected to these membranes,
and consequently to the uterus of the mother ; from which
its nourishment is derived until the time of birth. It will,
therefore, be the natural method to pass from the description
of the uterus to that of the membranes, and other parts of
the after-birth ; and to consider in the last place whatever
may be worthy of remark concerning the embryo itself.

§ 354. The mode of connexion of the pregnant uterus with
the membranes of the ovum, and thereby with the embryo
itself, displays three chief differences in the various mam-
malia.

Either the whole external surface of the ovum adheres to
the cavity of the uterus ; or the connexion is effected by
means of a simple placenta ; or by numerous small placentae
(cott/ledons).

§ 355. The first kind of structure is observed in the soiv ;f

* Much information on the subject of this and of the last chapter is contained in
Dr. J. F. Lobstein's Essais $ur la Nutrition du Foztus. Strasb. 1802, 4to. See also
some excellent observations on the cavities of the foetus in the three first classes of
red-blooded animals by Dutrochet, Cuvier, Breschet, Mondini, and Alessandrini, ia
Meckel's Archiv, vol. v. p. 535, and vol. vi. p. 385.

t Fab. Ab Aquapend. tab. 25 and 26. Daubenton, torn. v. tab. 21, 22.

358 ON THE FOETUS OF MAMMALIA.

and is still more manifest in the mare. In the latter case, the
external membrane of the ovum, the chorion, may be said to
form a bag-like placenta. Numerous and large branches of
the umbilical vessels ramify through it, particularly in the
latter half of the period of pregnancy ; and its external sur-
face is covered with innumerable flocculent papillae, which
connect it to the inside of the uterus.*

§ S5ß. In those animals of this class, where the embryo is
nourished by means of a placenta, remarkable varieties occur
in the several species ; sometimes in the form and successive
changes of the part, sometimes in the structure of the organ,
as being more simple or complicated.

In most of the digitated mammalia, as well as in the quad-
rumana, the placenta has a roundish form;+ yet it consists
sometimes of two halves lying near together ; and in the dog^
cat, martin, &c. it resembles a belt (clngulum ox zona). % Its
form in the pole-cat is intermediate between these two struc-
tures ; as there are two round masses joined by an intervening
narrower portion. §

I have discovered a most remarkable instance of change in
the form of this organ in the hedgehog. For some weeks
after impregnation the placenta includes nearly the whole cir-
cumference of the chorion, and may be compared, in size and
form, to a hazel-nut. It is spongy and vascular internally;
but on the outer surface firm and tough, and approaching to
cartilaginous hardness. It is not, however, of uniform strength
throughout ; but thinner and more flexible towards the con-
cave side of the cornua uteri, than on the opposite part. (See

* Fab. Ab Aquapend, tab. 21, 22 ; tab. 23, fig. 46.

t Daubenton, torn. vii. tab. 38, fig. 3, 4, of the rat.

Ibid. tab. 40, fig. 7, 8, of the domestic mouse; torn. viii. tab. 13, fig. 6, of the
mole.

X It is represented in the dog, by Eustachius, tab. anatom. tab. 14, fig. 7, 8, by
Fab. Ab Aquapend. tab. 27, 28 ; and by Daubenton, torn. v. tab. 50.

In the cat, by Needham, De Formato Fcetu, tab. 4. fig. 1 ; and Daubenton, torn,
vi. tab. 6.

In the martin, ibid. torn. vii. tab. 20.

§ Ibid.' torn. vii. tab. 27, •

ON THE FCETUS OF MAMMALIA. 359

Plate VIII. fig. 1.) As pregnancy advances, this thinner
portion increases, and gradually assumes a nearly membranous
structure, while the opposite thick part forms a firm and
dense placenta of a saddle-like shape with extenuated mar-
gins, (Plate VIII. fig. 2). This lies in the more mature
foetus nearly across the ilia; so that the neighbouring parts
are protected from any injury which might have arisen from
accidental pressure. For the final purpose of this singular,
and, as far as I know, unique construction, is the preservation
of the tender embryo in the abdomen of an animal, which rolls
itself up with such force, that, without this provision, the
pregnant uterus and its contents would be exposed to a most
dangerous pressure.

In several species of digitated mammalia the external sur-
face of the placenta is provided with a white and apparently
glandular body {corpus glandulosum Everardi,* or subpla-
centa,) smaller than the proper placenta by which it is in-
closed.f In proportion as the embryo becomes more mature,
this part admits of more easy separation from the placenta.

§ 357. The placenta of the bisulca is divided into numerous
cotyledons ; the structure of which is very interesting, as it
elucidates the whole physiology of this organ. The parts de-
signated by this appellation are certain fleshy excrescences,
[glandules uterince) produced from the surface of the impreg-
nated uterus, and having a corresponding number of floccu-
lent fasciculi of blood-vessels, {carunculcB) which grow from
the external surface of the chorion implanted in them. Thus
the uterine SLnAfczial portions of the placenta are manifestly
distinct from each other, and are easily separable as the foetus
advances to maturity. The latter only are discharged with the
after-birth, while the former, or the cotyledons, gradually dis-

* Cosmopulit(Z Ilistoria Naturalis, 1686, 12, p. 60.
t In the hare it is represented by Daubenton, torn. vi. tab. 46.
In the rahhit by Needham, tab. 3 ; and De Graaf, tab. 26, 27.
In the guinea-pig Vjy Fab. Ab Aquap. tab. 30 ; and Daubenton, torn. viii. tab. 4,
fig. 6.

In the water-rat, ibid. torn. vii. tab. 46, fig. 4, 5.

360 ON THE FCETUS OF MAMMALIA.

appear from the surface of the uterus after it has parted with
its contents. The number and form of these excrescences
vary in the different genera and species. In the sheep and
cow they sometimes amount to a hundred. In the former
animal and the goat, they are, as the name imphes, concave
eminences ;* while on the contrary, in the cow, deer, &c. their
surface is rounded or convex.t

§ 358. The trunks of the veins which pass from the pla-
centa or carunculse, and of the arteries which proceed towards
these parts, are united in the umbilical chord, which is longer
in the human embryoj than in any other animal. The navel,
which continues visible during life in man, is not so apparent
in other mammiferous animals.

In theyba^ as in the child, the chord possesses a single um-
bilical vein ;§ whilst most other quadrupeds have two, which
unite however into a common trunk near the body of the
foetus, or just within it.||

§ 359. The amnion, or innermost of the two membranes of
the ovum, which belongs to the pregnant woman, as well as to
the mammalia, is distinguished in some of the latter, as for in-
stance in the cow and mare, by its numerous blood-vessels ;
while on the contrary, in the human subject it possesses no
discernible vascular ramification.

§ 360. Between the chorion and amnion there is a part
found in most pregnant quadrupeds, and even in the cetaceat
which does not belong to the human ovum, viz. the allantoisy
or urinary membrane. The latter name is derived from the
connexion which this part has, by means of the urachus, with
the urinary bladder of the foetus ; whence the watery fluid,

* For a view of these parts in the sheep, see Fab. Ab Aquap. tab. 12, 14, 15.
t In the cow, Hoboken, particularly fig. 14 to 17.
In the goaf, Daubenton, torn. vi. tab. 17.

X The pole-cat probably has the shortest chord. Daubenton, torn. vii. tab, 27, fig.
3.

§ Ruini, p. 189.

II Hoboken, fig. 23, 27, in the calf.

ON THE FCETUS OF MAMMALIA. 361

which it contains, has been regarded as the urine of the ani-
mal. The term allantois has arisen from the sausage-Uke form
which the part possesses in the bisulca and the pig;* although
this shape is not found in several other genera and species.
Thus, in the hare, rabbit, guinea-pig, &c. " it resembles a
small flask ; and it is oval in the pole-cat. It covers the whole
internal surface of the chorion in the solidungula, and there-
fore incloses the foal with its amnion. It Contains most fre-
quently in these animals, (although not rarely in the cow)
larger or smaller masses of an apparently coagulated sediment
m various forms and number, which has been long known by
the singular name of the horse-venom or hippomanes.\

Some orders and genera of mammalia resemble the human
subject in having no allantois ; as the quadrumana and the
hedgehog : nay, in the latter animal, the urinary bladder has
no trace whatever of urachus ; which even exists in a certain
degree in the human subject ; but its fundus is perfectly
spherical in the foetus. (See Plate VIII. fig. 2, f.)

§ 361. There is in the hedgehog, as well as in the dog, cat,
and others, a peculiar part called the tunica erythroides, (see
Plate VIII. fig. 1, c ; fig 2, c) situated between the chorion
and amnion like the allantois, for which it might easily be
mistaken on the first view. It contains a watery fluid at the
commencement of pregnancy, but is easily distinguished from
an allantois, as it is not joined to the fundus of the bladder by
the urachus, but is connected by means of the omphalomesen-
teric veins, (Plate VIII. fig. 2, k) with the mesenteric blood-
vessels of the foetus.^ This connexion constitutes a resem-

* Fab. ab Aquap. tab. 13, fig. 29 ; and tab. 17, fig. 37, in the sheej,. J. C.
Kuhlemann has represented this part in an embryo of the nineteenth day after con-
ception. Observ. circa Negotium Generalionis in Ovibus. Götting. 1753, 4to. tab. 2,
fig. 1, 2.

Hoboken, fig. 10 to 13 and 15, in the cow. Fabric, tab. 25, in the pig,

t Daubenton, torn. iv. tab. 9, fig. 1, 2, of the horse.
Hoboken, fig. 19, 21, and fig. 37, of the cow.
^ Fab. Ab Aquap. tab. 1 , of the dog.
Needham, tab. 4, fig. 1, of the cat.

Wetter,

S62 ON THE FCETUS OF MAMMALIA.

blance on one hand to the yolk-bag of the incubated bird,
and on the other hand to that remarkable vesicula umbilicalis,
which is observable in the early months of pregnancy.* The
tunica erythroides, as well as that vesicula, are most complete
in young embryos, and are, on the contrary, so diminished in
subsequent periods, that their functions must be connected
with the earlier stages of existence. i

It is nearly forty years since I first showed the analogy be-
tween the tunica erythroides and the vesicula umbilicalis of
the human foetus, in the first months after impregnation, as
well as the natural state of the vesiculum umbilicale.;{:

The tunica erythroides was first noticed by Everard as existing in
animals, in his work entitled, Novus et genuinus hominis brutique ani-
malis exortus. Melib. 1661 ; and there is an engraving of it in Need-
ham's Observationes Anatomies, Leyd. 1743, under the name of corpus
glandulosum, Everardi quod fcetum utero connectit. Dr. Pochels of
Brunswick has lately endeavoured to prove its existence in the human
fcetus. See the Edinburgh Medical and Surgical Journal, vol. xxv.
No. 87 ; and The Lancet, vol. x. p. 456.

The first trace of the formation of an embryo cannot
be discovei-ed in the different species of this class until a con-
siderable time after conception. The original formation, as in
the human subject, is widely distant from the subsequent per-
fection of the mature foetus : § and the growth and formation

Wetter, tab. 4, oi the hedgehog. See also Drondi, Supplementa ad Anatomiam et
Fhysiologiam potissimum co7nparatam, Leip. 1806, p. 15.

* Comment. Soc. Reg. Scient. Getting, vol. ix. p. 128, fig. 1.

t See Oken's and Kieser's Beytr'dge zur vergleichenden Zoologie — Anatomie und
Physiologie, pt. 1 and 2, 1806 and 1807.

Meckel's Bey träge zur vergleichenden Anatomie, "p^. 1, 1808 ; and Archiv, für die
Physiologie, vol. ix. pt. 3, 1809.

Oken's Isis, 1818, p. 59.

X See Dr. EUiotson's excellent translation of the Institutiones PhysiologiecB, et
Specim. Physiolog. comparatx inter Animantia calidi sanguinis Vivipara et Ovipara,
1788, in the ninth vol, of the Commentat. Regalis Scient. Gotting.

§ See delineations of the embryo of different animals in the early .periods, viz. of
the ra&Wt in De Graaf, tab. 26, fig. 8, 10; and in Haller, Oper. Minor, torn. iii.
tab, 21, fig. 1-4. Of the sheep in Kuhlemann, tab. 2.

ON THE FCETUS OF MAMMALIA. B6S

of the members, instead of proceeding alike in the whole class,
are so ordered in particular species, that those external or-
gans, which are most necessary to the young animal, accord-
ing to its peculiar mode of life, are formed and completed the
soonest. Hence arises the great size of the posterior hands of
the foetal quadrumana, of the feet of the squirrel, of such ani-
mals in short as are destined to live in trees ; likewise of those
of theyb«/ and kid, which are obliged to use their legs imme-
diately after birth, when compared with the corresponding
parts of the mature human foetus.

In the foetal kangaroo, in that state at least in which it is
first found in the false belly, the fore feet are much larger and
stronger than the posterior ones, on account of the use to
which the animal puts them in holding by the nipple. When
the animal in a more mature state is in a manner born a second
time, and must soon be left to itself, the posterior limbs in-
crease to their well known enormous magnitude.

The erroneous observation concerning the supposed un-
shapeliness of the foetus of the bear, which has been so often
made since the time of Aristotle, would not require an express
refutation in the present day, had it not been repeated by some
modern zoologists, whose accuracy in general is much to be
relied on. I have completely shewn how unfounded this sup-
position is, by the representation of a young bear's foetus in
another place,* and it appears to be very completely formed.

§ 363. The most important points, in which the foetus of
the mammalia differs from that of the human subject, have
been already noticed. In other respects their structure seems
to correspond ;*t' at least, for instance, in the membrana pupil-
larisjj in the thymus, thyroid, and suprarenal glands. Some

* Abbildungen Naturhistor. Gegenstände, pt. 4, tab. 32.

t There is a view of the viscera of a foetal horse in Ruini, p. 189, and in
Daubenton, torn, iv. tab. 7.

Of the sheep in Kuhlemann, tab. 2, fig. 8.

Of the calf by Hoboken, fig. 24, 25.

i Wrisberg, in the Nov. Comment. Sac. Reg, Scient. Goetting, torn. ii. p. 207.

Vide

364) ON THE FCETUS OF MAMMALIA.

trivial points of distinction are not noticed ; such as the meco-
nium resembling hard scybala in the bisulca, and animals of the
mouse kind,* &c.

Vide S. C. Lucae Anatomische Untersuchungen der Thymus in Menschen und
Thieren. Frankf. 1811.

J. F. Meckel's Abhandlungen aus der menschlichen und vergleichenden Anatomie.
Halle, 1806.

* Fleming's Deutsche Jäger, p. 130; and Harvey De Generat. Animal, p. 197.

3Gt

CHAPTER XXVI.

ON THE BREASTS AND TEATS OF THE MAMMALIA.

§ 364. J HE nourishment of the young animal immediately
after birth, is derived in this class from the milk of the mother,
which is secreted in the breasts. This secretion, which is pe-
culiar to the class in question, has given rise to the name mam-
malia, by which Linnaeus has distinguished them. Teats have
been even discovered in the ornithorhynchus ;* but they seem
also to be wanting in the males of some other species, as the
hamster, and lemur mongoz ; although this sex possesses them
in general as well as the female. They are sometimes however
found in smaller number in the former sex, as in the dog, or in
a different situation, as in the horse.f

Numerous instances have occurred, in which milk has been
secreted in the breasts of male animals, as in the goat, ox, dog,
cat, and hare, as well as in men. I have treated more particu-
larly of this physiological phenomenon in describing a he-goat,%
which it was necessary to milk every other day for the space
of a year.§

Milk is commonly found in the breasts of newly-born chil-

* Home, in the Philos. Trans. 1802, p. 69.

t Daubenton, in Fourcroy's Medecine Eclairee, torn. ii. p. 274.

" Naturalists were long at a loss to discover the mammae and teats of this animal ;
in the male they were at length detected by BufFon, on the sheath of the penis. Mr.
J. Hunter also made the same remark, without knowing that Buffon had previously
noticed it ; these teats are largest in the foetus and young foal." Rees's Cyclop, art.
Anatomy of the Horse.

t The milking of he-goats, therefore, is not so extravagant a supposition as it ap-
peared to the shepherd in Virgil,

Qui Bavium non odit, amet tua carmina, Maevi ;
Atque idemjungat vulpes, et mulgeat hircos.

§ Hannoverschen Magazin. 1787, p. 753.

866 ON THE BREASTS AND TEATS OF MAMMALIA.

dren of both sexes ; and the same observation holds good in
the foal and calf.

Meckel gives the following account of his discovery of the mammae
in the ornithorhynchus, in his Ornithorhynclii paradoxi descriptio ana-
tomica, published at Leipsic in the year 1826. This elaborate mono-
graph contains the results of a minute dissection of a male and fe-
male ornithorhynchus, for which the author was indebted to the kind-
ness of Mr. Green, the distinguished Professor of Anatomy to the
Royal Academy.

It is well known to have been a common opinion, that the ornitho-
rhynchus and ornithorhynchus hystrix were destitute of mammse, and
that upon this opinion was founded the argument for rejecting those
animals from the class of mammalia. Cuvier, one of the latest writ-
ers on this subject, expressly states that they have no mammae ; and
after a careful examination of the male ornithorhynchus, I was myself
unable to detect any trace, either of papillae or glands. With respect
to the female, after having opened the abdomen, and removed the
greater part of the viscera, I was prevented by various occupations
from continuing my investigation of this subject, till the close of the
year 1823, when on the 25th day of December, a day of good omen,
I detected on the right side of the abdominal muscles, a small round
mass, which at first bore the appearance of a portion of intestine ac-
cidentally pushed into this situation, but upon carefully examining the
left side, I discovered a corresponding substance. The evening was^
too far advanced to permit me to pursue my investigation, but on the
next morning, after anight rendered sleepless by anxious expectation,
I returned to my work, and found that this substance was beyond all
question a glandular structure. I was equally satisfied that this gland
was a true mamma, an opinion which was more forcibly impressed
upon my mind from its structure and situation, from its marked de-
velopment in the female, and the want of it in the male, or at least
its existence in so minute a degree as to have hitherto eluded the
closest examination.

The following is an account of the situation, size, and structure of
this gland. It is placed on the side of the abdomen, between the
fleshy portion to which it adheres very loosely, the obliquus descen-
dens abdominis and the anterior muscles of the femur, reaching at its
upper extremity the external margin of the pectoralis major, and the
lower extremity of the sternum. The marked development of this
part renders it as surprising that it should hitherto have escaped no-
tice, especially as so many ornithorhynchi, and among these so many
females, have been dissected. The length of this gland was four
inches, three lines ; its breadth, about one inch, three or four lines ;
its greatest thickness four lines : its external shape is very oblong,
as indeed is evident firom these dimensions'; its breadth is nearly uni-
form, but is a little narrower towards the lower extremity. There are

ON THE BREASTS AND TEATS OF MAMMALIA. 367

exceedingly minute excretory ducts in the middle of the gland, which
open externally. Although I could pass neither silk nor mercury
through the ducts, which were of themselves, as I have observed, ex-
ceedingly narrow, and further contracted by the spirit of wine, and
filled with a thick fluid, the area was nevertheless indicated in the
skin. Although this part was covered with hair, there appeared ne-
vertheless, upon removing them, an opening of about five lines in
length, and three in breadth, surrounded with about eighty minute
foramina, from which the hairs proceeded, and which were probably
the orifices of the excretory ducts. There was, moreover, in the cen-
tre of this opening, a small depression of about two lines in diameter,
destitute of hair, but having several unequal rugae, among which
one not equalling the size of a millet-seed, was more conspicuous
than the rest. These were undoubtedly papillae, and orifices of the
ducts.

This discovery confirms the opinions of Oken and de Blainville,
who although they had never examined a female oi'nithorhynchus, ne-
vertheless asserted that there could be no doubt of the existence of
mammae, on account of the numerous analogies presented by that
animal with the other mammalia. This discovery also refutes the ar-
guments of those who inferred a want of mammae from the absence of
nipples, from the shape of the bill, which is by no means adapted for
sucking, and from ova said to have been found in the ovaries, and in
nests, though there could be no foundation for this last assertion.

§ S65. The position and number of the teats varies consi-
derably in the different species. Several irregularities occur
in the latter point, particularly among the domestic animals.*
Numerous exceptions must be made in some species, as the
domestic sow, the guinea-pig, and others, to the general rule,
which assigns to animals twice as many teats as the number of
young which they ordinarily produce.

Their situation is the most singular in the female marsupial
animals, where there existence can scarcely be recognized, ex-
cept at the time when the young are actually contained in the
abdominal pouch, or false belly.

Tyson, who on all other occasions displays the greatest
acuteness, could discover no trace of teats in his female opos-
sum. D'Aboville expressly asserts, that they are formed by
the suction of the young, that their number, therefore, in ani-
mals which are giving suck, exactly corresponds to the num-

* Buffon, torn. x. p. 295.

368 ON THE BREASTS AND TEATS OF MAMMALIA.

ber of young at that period ; and that they are placed without
any symmetry, being formed wherever the young animals may
happen to attach themselves on their arrival in the abdominal
pouch.*

In an opossum which I possessed for several years, and
whose Ovaria discovered no trace of any previous impregna-
tion, there were three pairs of teats in the false belly, very
small indeed, and flat, but regularly arranged in a half-moon.

A species of toad (the rana pipa, or Surinam toad) has a structure
somewhat analogous to the false belly of the marsupial mammalia.
There are several cells, amounting in number to seventy or eighty,
formed by the integuments of the back of the female. The ova are
placed in these, and go through their different changes to the forma-
tion of the young fro^. The integuments which form these cells,
appear to have no peculiarity in their organization ; nor are the cells
formed until the time at which they are to receive the ova.

§ 366. In the singular animals which have been just alluded
to, as well as in those which live in the water, or under
ground, the mammary glands, for reasons which must be very
obvious, lie flat under the skin, and do not project so as to
form breasts or udders ; neither do the lactiferous ducts pos-
sess such dilatations and cavities as are observed in the bisulca,
the mare, and others.'!' In those animals which have their
breasts placed on the chest, (mammce pectorales) these organs
never possess that form which so peculiarly distinguishes the ,
human female in the bloom of life.

The mammae of animals are not surrounded with that quantity of
fat which is observed in the human female, hence they are not very
apparent except at the period of suckling, when they become dis-
tended with milk.

Another remarkable difference occurs in the structure of the nip-
ple. This part in women has about fifteen openings, which are the
terminations of as many lactiferous tubes. In the other mammalia it
is hollow, and has only one or two orifices. Its cavity communicates
with two large reservoirs, in which the lactiferous tubes terminate.

* See Voyages du Marq. De Chastellux dans I'Amerique Septentrionale, torn. ii. p.
332.

t Daubenton, torn. v. tab. 12, of a goat which had double teats on each udder.
See also Steinmiiller's Beschreibung der schweizerischen Alpenwirthschaft, vol. ii. p. 150.

369

CHAPTER XXVII.

ON THE INCUBATED EGG.

§ 867. 1 HE various vital processes of nutrition and formation,
which are carried on in the foetus of the mammaha, while in
its mother's body, and by means of the most intimate connex-
ion with the parent, are effected in the incubated chick by its
own powers, quite independently of the mother, and without
any extraneous assistance, except that of the atmospheric air,
and a certain degree of warmth.

§ 368. The egg is covered, within the shell, by a white
and firm membrane, {memhrana albuminis) which contains no
blood-vessels. The two layers of this membrane, which in
other parts adhere closely to each other, leave at the large
end a space which is filled with atmospheric air.*

This membrane includes the two whites of the egg, each of
which is surrounded by a delicate membrane. The external
of these is the most fluid and transparent, the inner one
thicker and more opaque; they may be separated in eggs
which are boiled hard.

The internal white surrounds the yolk, which is contained
in a peculiar membrane called the yolk-bag. From each end
of this proceeds a white knotty body, which terminates in a
flocculent extremity in the albumen. These are called the

• J, C. Hehl, Observata Physiolugica de Natura et Usu Aeris, Ovis Avium inclusi.
Tubing. 1796, 4to.

See Dr. Parls's admirable paper on this subject, in the Transactions of the Linn(Ban
Society, vol. x. p. 2, 304.

2 B

370 ON THE INCUBATED EGG.

chalazcBt or grandines. Leveille distinguishes a third white,
and considers the chalazae as absorbing vessels floating in it,
and destined to absorb it as well as the inner albumen, and
mix them with the yolk during incubation.*

A small, round, milk-white spot, called the tread of the
cock, (cicatricula or macula) is formed on the surface of the
yolk-bag. It is surrounded by one, or more, whitish concen-
tric circles, {halones or circuU) the use of which, as well as
that of the cicatricula itself, and of the chalazae, is not yet as-
certained.

§ 369. We now proceed to notice the wonderful successive
changes which go on during the incubation of the egg ; and
the metamorphoses which are observed both in the general
form of the chick, and in particular viscera. The periods of
these changes will be set down from the hen, as affording the
most familiar examplcf* It will be best to give, first, a cur-
sory chronological J view of the whole process, and then to
make a few remarks on some of the most important parts of
the subject.

§ 370. A small shining spot of an elongated form, with

* Sur la Nutrition des Fcetus. Par. 1799, 8vo.

t The following works may be referred to for representations of the formation of
the chicken in the egg.

Malpighi, De Formatione Pulli. Lond. 1673, 4to. ; also De Ovo Incubato, 1686,
fol.

W. Langly, in Schrader, Observ, et Histor. de Generatione. Amst. 1674, 12nio,
Ant, Maitre-Jan, Observat. sur la Formation du Foulet, Par. 1722, 12mo.
C. F. Wolff. Theoria Generationis. Hal. 1759, 4to. tab. 2 ; also in the Nov. Com-
ment. Acad. Petropolitan. torn. xii. xiii. and xiv.

Meckel, Beytr'dge zur vergleichenden Anatomie, vol. i. pt. 1, p. 83.
And Sir E. Home's Lectures on comparative Anatomy.

As the plates of Langly and Wolff represent only the earlier periods, and the others
are not executed with that elegance and clearness which they ought to possess ; I
have given in the fourth and seventh parts of my Abbildungen der Naturhistorich-Ge-
genstände, some neat and accurate representations, taken from two periods, in which
the most important phenomena of incubation are most clearly discernible.

I The periods of the different changes are set down as I have ascertained them in
my own repeated observations.

ON THE INCUBATED EGG. 371

rounded extremities, but narrowest in the middle, is per-
ceived at the end of the first day, not in nor upon the cica-
tricula, but very near that part on the yolk-bag, {nidus pulli,
coUiquamentmn, areola pelhwida). This may be said to ap-
pear before-hand, as the abode of the chick which is to follow.
No trace of the latter can be discerned before the beginning
of the second day, and then it has an incurvated form, resem-
bling a gelatinous filament, with large extremities, very closely
surrounded by the amnion, which, at first, can scarcely be dis-
tinguished from it.

About this time the halones enlarge their circles, but they
soon after disappear entirely, as well as the cicatricula.

§ 371. The first appearance of red blood is discerned on
the surface of the yolk-bag, towards the end of the second
day. A series of points is observed, which form grooves, and
these, closing, constitute vessels, the trunks of which become
connected to the chick. The vascular surface itself is called
ßgiira venosa, or area vasculosa: and the vessel by which its
margin is defined, vena terminalis. The trunk of all the veins
joins the vena portag, while the arteries, which ramify on the
yolk-bag, arise from the mesenteric artery of the chick.

§ 372. On the commencement of the third day, the newly-
formed heart (the primary organ of the circulating process,
which now commences) is discerned by means of its triple
pulsation, and constitutes a threefold jo?/wc/?/m saliens. Some
parts of the incubated chicken are destined to undergo suc-
cessive alterations in their form ; and this holds good of the
heart in particular. In its first formation it resembles a tor-
tuous canal, and consists of three dilatations lying close toge-
ther, and arranged in a triangle. One of these, which is
properly the right, is then the common auricle ; the other is
the only ventricle, but afterwards the left ; and the third is
the dilated part of the aorta (hulbus aortce).

About the same time, the spine, which was originally ex-
tended in a straight line, becomes incurvated ; and the dis-
tinction of the vertebrae is very plain. The eyes may be
distinguished by their black pigment, and comparatively im-

2 D ^

,372 ON THE INCUBATED EGG.

mense size ; and they are afterwards remarkable in conse-
quence of a peculiar slit in the lower part of the iris.*

I have found an exactly similar slit in the iris of the common
lizard, {lacerta agilis) before it had attained maturity. Thus
this structure belongs to such animals as have no memhrana
pupillaris.

§ 37o. From the fourth day, when the chicken has attained
the length of four lines, and its most important abdominal
viscera, as the stomach, intestines, and liver, are visible, (the
gall bladder, however, does not appear till the sixth day,) a
vascular membrane {chorioti, or memhrana umbilicalis) begins
to form about the navel ; and increases in the following days
with such rapidity, that it covers nearly the whole inner sur-
face of the shell within the memhrana albuminis during the
latter half of incubation. This seems to supply the place of
the lungs, and to carry on the respiratory process instead of
those organs. The lungs themselves begin indeed to be
formed on the fifth day ; but, as in the foetus of the mammalia,
they must be quite incapable of performing their functions
while the chick is contained in the amnion.

§ 374. Voluntary motion is first observed on the sixth day,
when the chick is about seven lines in length.

Ossification commences on the ninth day, when the ossific
juice is first secreted, and hardened into bony points {puncta
ossificationis). These form the rudiments of the bony ring of
the sclerotica, which resembles at that time a circular row of
the most delicate pearls. I have found this part much more
elegantly formed than in the hen, in the incubated pea-fowl
of the fourteenth and following days.

At the same period, the marks of the elegant yellow vessels
{vasa vitelli lutea) on the yolk-bag, begin to be visible.

• Malpighi, Be Format. Pulli, tab. 2, fig. 18, 21 ; and De Ovo, tab. 3, üg, 18,
20 ; tab. 4, fig. 21.

Abbildungen, n. G. pt. 7, tab. 64.

See also Haller Sur la Formation du Cceur dans le Poulet, torn, i, pp. 193, 194 j
torn. ii. p. 160.

ON THE INCUBATED EGG. 373

On the fourteenth day the feathers appear ; and the animal
is now able to open its mouth for air, if taken out of the egg.

On the nineteenth day it is able to utter sounds ; and on the
twenty-first to break through its prison, and commence a
second life.

§ 375. We shall conclude with one or two remarks on those
very singular membranes, the yolk-bag and chorion, which
are so essential to the life and preservation of the animal.

The chorion, that most simple yet most perfect temporary
substitute for the lungs, if examined in the latter half of incu-
bation in an egg very cautiously opened, presents, without
any artificial injection, one of the most splendid spectacles
that occurs in the whole organic creation. It exhibits a sur-
face covered with numberless ramifications of arterial and
venous vessels. The latter are of the bright scarlet colour,
as they carry oxygenated blood to the chick ; the arteries, on
the contrary, are of the deep or livid red, and bring the car-
bonated blood from the body of the animal. Hence, as is
well known, the incubated bird perishes if the shell be var-
nished over, as the respiratory process is thereby suspended.
The trunks of the arteries are connected with the iliac ves-
sels ; and on account of the thinness of their coats, they afford
the best microscopical object for demonstrating the circula-
lation in a warm-blooded animal.

§376. The other membrane, the membr ana vitelli, is also
connected to the body of the chick ; but by a two-fold union,
and in a very different manner from the former. It is joined
to the small intestine, by means of the ductus mtello-miestina-
lis, (pedunculus, apopJiysis) and also by the blood-vessels,
which have been already mentioned, (§ 368) with the mesen-
teric artery and vena portae. This is regarded by Leveille
merely as a ligament. It is well known that no true yolk is
discoverable in the intestine of the incubated chick. Yet
sometimes (not indeed always, but under certain circum-
stances not yet sufficiently understood) air will pass from the
intestine through this part into the yolk-bag. This fact,
which was noticed by Haller, and after him by Maitrejan, has

374 ON THE INCUBATED EGG.

occurred also to myself in the case of a duck of the twenty-se-
cond day.

The analogous umbilical bag of the fcetal-shark, (which is
found also in several other fishes, and some reptiles) is con-
nected to the small intestine'; at least to the bursa entiana,
which is a peculiar dilatation of the posterior end of the intes-
tine.*

In the course of the incubation the yolk becomes constantly
thinner and paler by the admixture of the inner white. At
the same time innumerable fringe-like vessels with flocculent
extremities, of a most singular and unexampled structure,
form on the inner surface of the yolk-bag, opposite to the
yellow ramified marks above-mentioned, and hang into the
yolk.* There can be no doubt that they have the office of ab-
sorbing the yolk, and conveying it into the veins of the yolk-
bag ;'f' where it is assimilated to the blood, and applied to the
nutrition of the chick. Thus, in the chicken, which has just
quitted the egg, there is only a remainder of the yolk and its
bag to be discovered in the abdomen. These are completely
removed in the following weeks, so that the only remaining
trace is a kind of cicatrix on the surface of the intestine.

* Collins, vol. ii. tab. 33, fig. 2 ; and Charleton De Differentiis Animalium, p.
84. Augs. 1677.

\ In numerous and varied microscopical examinations of the yolk-bag in the lat-
ter weeks of incubation, I think I have observed the actual passage of the yolk from
the yellow flocculent vessels of the inner surface of the bag into the blood-vessels,
vrhich go to the chicken : that is, I have seen manifest yellow streaks in the red
blood contained in those veins.

EXPLANATION OF THE PLATES *

Excepting in Plate II. and fig. 2 of Plate VIII. the objects are repre-
sented of the natural size.

PLATE I.

The Skull of the duck-billed animal {prnithorhynchus para-
doxus). A piece of the right side of the cranium has been
broken off* to shew the interior. The skull is devoid of
sutures.

a, b. The two occipital condyles.

c. The pecuhar bony falx.

d. The OS malare.

e. The right orbit.

f. The broad processus mandibularis of the upper jaw.

g. A similar process on the lower jaw.
h. The condyloid process of the jaw.

i. The serrated edge of the fore and lateral part of the jaw,

as in the duck.
k. The second branch of the fifth pair of nerves.
1, m, p. Twigs of this branch distributed to the integuments

covering the bill,
n, o. The intermaxillary bone of this side.

• These Plates were not pveu in the original edition.

376 EXPLANATION OF THE PLATES.

PLATE II.

The Pelvis and Ossa Femorum of the ostrich {struthio ca-

nielus).

a, b. The os sacrum, (twenty inches long).
c, d, e. The ossa innominata, united anteriorly.
f, g. The ossa femorum, entirely devoid of medullary sub-
stance.

PLATE III.

The right articulated Wing of the Cape lienguin {aplenodytes

demersa).

The wing-bones are particularly distinguished by their very
flat and compressed form, by two additional bones on the
elbow, as well as by the want of the bone of the thumb.

1, The lower ends of the bone of the upper arm.
2i S. The two additional bones.

4. The ulna.

5. The radius.

6. 7. The two bones in the carpus.

8. The divided os metacarpi.

9, 10. The two phalanges of the forefinger.

n. The adjoining finger consisting only of one phalanx.

PLATE IV.

The Skull of a duck^ more particularly for the purposes of
comparison with the same part in the ornithorkynchus,

(PL. I.).

a. The single occipital condyle.
T). The OS quadratum.
c. The ossa lachrymalia.

EXPLANATION OF THE PLATES. 377

d. The elastic laminas of bone for the moveable connexion

of the upper jaw with the cranium.

e. The membranous conchae of the nares.

f. i. The first branch of the fifth pair.

g. Tv?igs of this nerve to the integuments covering the

upper mandible,
h, i. The second branch of the fifth pair,
k, 1, m. Distribution of this branch to the upper mandible,
h, n. The third branch of the fifth pair,
o. A twig to the integuments of the lower mandible.

PLATE V.

A vertical Section of the Skull and Upper Mandible of a young
toucan {tucanus ramphastos).

a. The cavity of the cranium.

b. The membranous conchse of the nares.

c. A large fossa in the bill before these conchas.

d. A membranous vertical septum by which this fossa is di-

vided.

e. f. The horny upper mandible, the internal structure of

which is cellular.

PLATE VL

The Eye of a Greenland seal (phoca gro'inlandica).

a. The very thin cornea.

b. The thick anterior zone of the sclerotica.

c. The thin, yielding middle zone and its diameter.

d. The posterior part of the sclerotica, very thick, and al-

most of a cartilaginous structure.

e. The broad ciliaris orbicularis,

f. The iris.

378 EXPLANATION OF THE PLATES.

g. The pupil.

h. The anterior surface of the crystalline lens.

i. The optic nerve.

PLATE VII.

The Female Organs of Generation in the opossum (didelphis
marsupialis) with the neighbouring viscera. The vagina is
laid open from the side.

a, b. The part common to both vaginae.

c. The double clitoris, with the glans projecting from the

foreskin.

d. The opening of the urethra.

e. The vagina of the left side, unopened.

f. The vagina leading to the right side, with the part com-

mon to botli longitudinally divided and kept apart
from each other.

g. The large lateral convolution on the right side of the

uterus.

h. This, together with the one of the opposite side, o, open-
ing into a common cavity.

i, k. The cornua uteri.

1. The fine and tortuous convolutions of the right Fallopian
tube.

m. The ovarium.

n, o, p, q, r, s. The same parts on the left side.

t. The empty bladder.

u, u. The end of the large intestines.

V. The anus.

w, X. The scent bags.

y, z. The openings of their excretory ducts.

EXPLANATION OF THE PLATES. 379

PLATE VIII.

Embryos of hedgehogs at different periods, to show the
changes which occur in the placenta.

Fig. 1.
A very young Embryo.

a, b, b. The oval chorion opened ; the anterior half having
been removed.

a. Its thick, and nearly cartilaginous portion.

b. b. The thinner lubricated parts.

c. The tunica erythroides.

d. The embryo, with its amnion, which had hitherto been

inclosed in the chorion.

Fig. 2.
An Embryo in a more mature state.

a, b. The saddle-shaped placenta.

c. The tunica erythroides.

d. The abdomen of the embryo opened ; its intestines and

vessels are represented in fig. 1.

e. The liver.

f. The bladder without urachus.

g. h. The two umbilical arteries.
i. The umbilical vein.

k. The omphalomeseraic vessels.

THE END.

J. WCreery, Took» Court,
Cbancery-laoe, LooiloD.

M

f^i

K?M.

J'i.imfi-.Sc.FHltM-in)i.teTfio

riihU.shM hv Suni'Un ,<■ M.irs/iiiU (W-t'l'i/l-.-r.

M?]

K.MinwSi-,rul.-rn..M,-i-H„w.

hihlLfhal /;)' Simpkii, .(■ Manlmll ii,ir.i'f'^i8Q7.

^

^t#

sr?T«

Frauicr Sc. P;UemoiiVefRo

f'uhh.rhiJ hy SimpkinX- Mnivluill O.iUf-Jl'J?-

I^?1ÖDI,

Fennor.S.-.IV,l.-n rli.,

njhlLheJ In- Si/npkiri Ji- M.irsh.ill <lri:i''.' iHj?.

^'^Ym,

i C,"

v^>

Id

FoontT S.-.I'aI.-ni.>iil.T H,,

fnhlij'lu.l /;> Siiiiflxin (• .\hi:vluill .I'.-iri'l' h1.f.

COLUMBIA UNIVERSITY LIBRARIES

This book is due on the date indicated below, or at the
expiration of a definite period after the date of borrowing, as
provided by the rules of the Library or by special arrange-
ment with the Librarian in charge.

DATE BORROWED

DATE DUE

DATE BORROWED

DATE DUE

I'

C28(i14i)m100

QL305

Blumenbaoh
A. manual

Q4 f^s

B622
L327

.tonjy.