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Le EAI A CEN RI. Aap TI

THE

JOURNAL.

OF

ANATOMY AND PHYSIOLOGY
NORMAL AND PATHOLOGICAL,

HUMAN AND COMPARATIVE.

aor

THE

JOURNAL

OF

ANATOMY AND PHYSIOLOGY

NORMAL AND PATHOLOGICAL,
HUMAN AND COMPARATIVE

CONDUCTED BY
SIR WILLIAM TURNER, K.C.B., M.B., LL.D., D.C.L., D.Sc., F.RS.,

PROFESSOR OF ANATOMY IN THE UNIVERSITY OF EDINBURGH ;

D. J. CUNNINGHAM, M.D., D.Sc. LL.D., D.C.L., F.RS.,

PROFESSOR OF ANATOMY AND CHIRURGERY IN THE UNIVERSITY OF DUBLIN ;

G. S. HUNTINGTON, A.M., M.D.,

PROFESSOR OF ANATOMY, COLUMBIAN UNIVERSITY, NEW YORK ;

A. MACALISTER, M.D., LL.D., D.Sc., F.R.S., F.S.A.,

PROFESSOR OF ANATOMY IN THE UNIVERSITY OF CAMBRIDGE ;
AND

J. G. MSKENDRICK, M.D., LL.D., F.R.S.,

PROFESSOR OF THE INSTITUTES OF MEDICINE IN THE UNIVERSITY OF GLASGOW.

VOL, XXXVILI.
NEW SERIES—VOLUME XVII.

WITH XXXII. PLATES AND NUMEROUS ILLUSTRATIONS IN a

Woes Sy
LONDON: rll

CHARLES GRIFFIN AND COMPANY, Lrp.
EXETER STREET, STRAND.

1903,

t
q
-

es

CONTENTS.

FIRST PART—OCTOBER 1902.

PAGE
Tue Eanty STaces or THE DEVELOPMENT OF THE PERICARDIUM. By

Pror. ArrHurR Roprnson, M.D., M.R.C.S. (Plates I., IL.)...........++ 1

Tue EXTENT TO WHICH THE PosTeRIOR SEGMENTS OF THE BoDY HAVE
BEEN TRANSMUTED AND SUPPRESSED IN THE EvVoLUTION OF MAN
AND ALLIED Primates. By Arraur Kerru, M.D., F.R.C.S. ......... 18

Some CARDIOGRAPHIC TRACINGS FROM THE BASE oF THE HuMAN Heart.
By Asriey V. Ciarke, M.D. (Cantab.), and J. SHouro C. Dovetas.., 41

A Srupy or THE CEREBRAL Correx IN A CASE oF CONGENITAL ABSENCE
oF THE Lert Urren Lins. By T. G. Moorneap, M.B., B.Ch.
RD s oan svss ch geiarsoscavesss sxcuphiars eee here eh Wed, bs fobs ys 46

Tue Foxm or rut HUMAN SpLeEN, By R, K. Snernern, B,Se. ............. 50

PRELIMINARY Nore ON THE PostIrioN OF THE GALL-BLADDER IN THE
HumAN Supsecr. By E. Scorr Carmicuak., M.B., F.R.C.S.E ........ 70

THE DEVELOPMEN? oF THE Heap MusciEs 1N Seyllium Canicula. By F.
Remmonwourn, M.B., B.Sc. (Plates 1V.-X.) .0.....,.ccccsscncecvsseseseseee 73

THE SKELETON OF A NATIVE AusTRALIAN. By W. H, Broan, M.B., Ch.B. 89

PROCEEDINGS OF THE ANATOMICAL Socrery OF GREAT BRITAIN AND
MAF P4 cd 5trd6acws .ss0b2 ts 654i sdecdanbovedseyscascooanas yt thce eee 97 (Ixi-Ixxvi)

SECOND PART—JANUARY 1903.

Are THE CRANIAL ConrENTS DisPpLACED AND THE BRAIN DAMAGED BY
Freezine tHe Entire Heap? By Pror. Jounson Symineton, M.D.

I BO Siew lca Wed egg stacksouesvxacrebnes sas ssspccsvieans si hee 97
On THE DEVELOPMENT OF THE Preryoo-qUADRATE ARCH IN THE LaceR-
aa. By R..Broom, M.D.; B.Sc., C.M.Z.8. 0... cc icsccvecssesscccescne o. 107

Ox THE DEVELOPMENT AND HOMOLOGY OF THE MAMMALIAN CEREBELLAR
Fissures. By Pror, O. CHarnook BRAviEY, M.B. Part I. (Plates
He Le) crosiaccscse eogurtdagiis sushi ibnieciatanded kin ciedsdace Made sitiodbaeiers LZ

vi CONTENTS.

SECOND PART—continued.
PAGE
Tue EvoLution or THE TeerH IN THE MAMMALIA. By H. W. MArerr

, Tras, B.A. (Camb.), M.D., M.Ch. (Edin.) ......sssseessesecssesesseeves ea | Se

Tue Form oF THE DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN
Arropny. By J. O. Waxetin Barrarr, M.D, (Lond.), F.R.C.S.

UWoalae ae cics Se stacey ova acs seanks Caelysubueasubaceysbasvoussssteyibiadss¥iss pacman 150
ON THE ORIGIN OF VERTEBRATES DEDUCED FROM THE STUDY OF AMMO-
cares. By Watrer H. Gaske.t, M.D., LL.D., F.R.S,........... 4. 168

PROCEEDINGS OF THE ANATOMICAL SocrETY OF GREAT BRITAIN AND
RMD AIS gs 5 5 cses anc se casa ca Reh epo bea Na ske ease) Cot aeee ee Mor dS 221 (i-xxxix)

THIRD PART—APRIL 1903.

DEVELOPMENT AND HoMoLoGy OF THE MAMMALIAN CEREBELLAR FISSURES.
By Pror. O. CuArnock Brapiey, Part II. (Plates XVII.—XXIII.).. 221

OBSERVATIONS ON THE RELATIONS OF THE DEEPER PARTS OF THE BRAIN
To THE SurFAcE. By Pror. JoHnson Symineton, M.D. (Plates
6.4 i >. 0.4 0. Peep r een erst reer yr fe 241

An EXAMPLE OF A PECULIAR MALFORMATION OF THE TRICUSPID VALVE OF
tHE Heart. By Pror, T. Warprop Grirrira, M.D., M.R.C.P.
(Plate XAX.) ce 8Nieshies LEDER DAR te Peet Se 62 MPRA ee 251

Nore on A SECOND EXAMPLE OF DIVISION oF THE CAVITY OF THE LEFT
AURICLE INTO Two COMPARTMENTS BY A Frerous BAnp. By Pror.
T, Warprop GriFFitH, M.D., M.R.C.P. (Plate XXXI.).................. 255

Tue CEREBRUM OF A MicrocePHALIc Ipior. By N. C. MAcNAMARA,
F.R.C.S.;,.and Re He BUBNE Ls.) ssc. cies cSsteaedasvesese ce csch ove noaesh Onaaamn 258

SomE ANOMALIES IN NERVES ARISING FROM THE LUMBAR PLEXUS, AND A
BILAMINAR MtuscuLus PECTINEUS IN A Fa@Tus; AND ON VARIATIONS
tN NERVE SuPPLY IN MAN AND SOME OTHER MAMMALS. By EDWARD ~
B;iJamirEson, M.B., Oh. By (Edin. ).... ccizicagesste cies vacesetmepeanns ceva rela 266

CoMPLETE ABSENCE OF THE SUPERFICIAL FLExXORS OF THE THUMB AND
CONCURRENT MuscuLaAr ANOMALIES. By H. S. Haun, B.A. (Plate
D. ©. ©.0 ED Rarer ere eid A Rod oa See eueeeseees Gaseedecus dooce; ens eeee ten, ees

A Meruop or OBTAINING UNIPLANAR SECTIONS WITH THE ORDINARY
Rocxrne Microrome. By W. Sampson HanpDiey, M.S. (Lond.)....... 290

ARCHMOLOGIA. ANATOMICA., cs sicsccccscosshicccdescecceccescessecenss eyes edna 293

THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE. By PROF.
BesTRamM C.’A. WEINDLE, MLD., Sc.D. , F.B-S., :..5...-..¢4s2ssdeesdeeeeaeeekeene

PROCEEDINGS OF THE ANATOMICAL SocrETY oF GREAT BRITAIN AND
TRELAND..),... hoauiesenesvebencenslae cued phaqis s/t pe eaaeaannae Scene 315 (xli-l)

a

——— |

CONTENTS. vii

FOURTH PART—JULY 1903.
PAGE
Tue MEANING OF SOME OF THE EPIpHYsES oF THE PeELvis. By F. G.

NEE Seca poise: hue is eaaabeevimebeataRatA ines i peuduetlosaady-vepasesyeus ws 315:
THE SO-CALLED ‘Gyrus Hippocamp.’ By Pror. G. Exxior Smirx, M.D, 324

Nores oN THE MorpPHoLocy or THE CEREBELLUM. By Pror. G. ELLior
I D0, 5 5.0 5c du quscicetakeuddgureinghateeaM Maaie? Goemrsieser¥nvnceses 329

PRELIMINARY COMMUNICATION ON SOME CEPHALOMETRIC DATA BEARING
UPON THE RELATION OF THE SIZE AND SHAPE OF THE HEAD TO
MENTAL Asiuity.. By Dr R. J. GLADSTONE.............0cccccscoscesecseees 333

ForM-RELATIONS OF THE DILATED CEREBRAL VENTRICLES IN CHRONIC
Brain Atropuy. By J. O. WAKELIN Barratt, M.D.............0.-.008 347

ABNORMALITIES IN SACRAL AND LUMBAR VERTEBR# OF SKELETONS OF
AUSTRALIAN ABporIGINES. By Dr W. RAMSAY SMITH..............2.000 359

RUDIMENTARY CoNnDITION oF CaroTipD CANAL, By G, H. K. MAcALisTER,
ere pb xvanié wes -eeameaela siamteont alta pwbadess tian nba Vine actin dan . 362

Some PecuLiar FEATURES IN 4 TEMPORAL Bone. By P. P. LAIDiAw..... 364 —

CASE OF FEATHER-BirurcATION. By W. J. RUTHERFURD...................... 368
OccURRENCE oF A ‘Principal IsLET’ IN THE PANCREAS OF TELEOSTEI,
{Preliminary Note.) By JoHN RENNIE, B.Sc, ............:0.ccsseeeeeeeeeeees 375
Mernop or PRerarinc THE MemBRANovs LABYRINTH. By ALBERT A.
IN ae ibn Mian coiCDesdbaanang Jaloesacuatawus dnd es <iScdanWbngeeite sé saab ruseates 279
Two HEARTS SHOWING PECULIARITIES OF THE GREAT VEINS. By Davip
INCVINES DD oss aciwsyacaccccvesupipsvoadoes Heviosveeswbodekeieistarsnicccduiebaes 382
GENERAL CHARACTERS OF CRANIA OF PEOPLE oF SCOTLAND. By Sim
INNS BO), Tinos oun hen od nadie gootansuaehs i vecacuswadybauve vase opasve 392
einer parc thes- «03 issupubaddasQiteshs-sdoestneqsabeing ponte wvereocsee 409
PROCEEDINGS OF THE ANATOMICAL SocreTY oF GreAT BRITAIN AND
ei Lace tcenh cca cscdesdesssesiaselscescdvacasecnstesacsbrinepess 411 (li-lxv)

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Journal of Anatomp and Phpsiology.

THE EARLY STAGES OF THE DEVELOPMENT OF THE
PERICARDIUM. By Arruur Ropinson, M.D., M.R.C.S.,
Professor of Anatomy, King’s College, London. (PLATES

L, IL.)

THE development of the pericardium has usually been considered
in association with the development of the great veins and with
the development of the diaphragm. In consequence of this much
stress has been laid upon phenomena which have no direct
bearing upon the formation of the pericardium itself, and the
essential simplicity of the process has been obscured, to a
certain extent, by the use of terms which are not in all cases
appropriate, and in many are misleading. As a result a large
amount of misconception exists with regard to the details of the
formation of this important serous sac in mammals, and this
misconception is mainly due to inaccurate descriptions of the
mode in which the embryo is evolved from the surface of the
ovum.
The incorrect descriptions most responsible for the misunder-
standing are those which ascribe the demarcation of the embryo
and its separation from the non-embryonic part of the ovum as
due to the formation of sulci, which appear round the margins
of the embryonic area and gradually converge beneath it to form
the boundary of a continually narrowing orifice—the umbilical
orifice ; in other words, to descriptions which lead their readers
to infer that the embryo is demarcated by a process of tucking
off from the ovum, whilst at the same time it is moulded into its
proper form,

In association with this misconception of the manner in
which the embryo is separated from the remainder of the ovum,

VOL. XXXVII. (N.S. VOL. XVII.)—OCT. 1902. ° 1

om PROFESSOR ARTHUR ROBINSON.

a description of the early stages of the development of the
pericardium is given which, at first sight, is apparently in
accordance with the appearances observed in transverse sections
of developing ova; but when the examination of such sections
is controlled by the observation of longitudinal sections in
similar stages of development, then it is found that the appear-_
ances seen in transverse sections are deceptive, and that the
phenomena observed are capable of a different interpretation
to that previously placed upon them.

It has been shown by the examination of transverse sections
that, whilst the embryonic area is still outspread upon the upper
part of the ovum, the mesoderm within its margins becomes cleft
into an outer or somatic and an inner or splanchnic layer, but
that in the antero-lateral parts of the area this cleavage of the
mesoderm does not extend either to the margins of the area or

Bo¢

Fic. 1.

to the sides of the neural groove, and that, consequently, on each
side a mesodermal tube is formed, and in the lower or splanchnic
layer of each of these tubes a longitudinal vessel appears which
has been described as a rudiment of the heart (fig. 1). The ex-
amination of sections of this kind, and the preconceived idea
that the folds of the embryo are formed by a process of tucking
in of the margins of the embryonic area, have led to the state-
ment that, as the lateral folds pass inwards beneath the growing
embryo and approach the mid-ventral line, the two mesodermal
tubes meet together and divide the anterior portion of the
blastodermic cavity into two parts, an upper (the foregut), and
a lower (the anterior part of the yolk sac), and that the so-
called rudiments of the heart, which lie in the inner walls of
the mesodermal tubes, also fuse at the same time to form a single
median heart (fig. 2). “ Obviously, at the period under considera-
tion, a heart developed in such a manner would be attached for

EARLY STAGES OF DEVELOPMENT OF THE PERICARDIUM. 3

a time by a fold of mesoderm to the foregut dorsally, and to the
yolk sac ventrally, but the idea that the lateral folds of the
embryo are converging ventrally has been held so tenaciously
as to establish the belief that the superficial ectodermal covering
of the folds also reaches the middle line; otherwise, it is im-
possible to account for the statement which constantly re-
appears, that after the lateral folds have converged and the
pericardial tubes have met beneath the ventral wall of the fore-
gut, the heart is not only attached by a dorsal mesentery to the
foregut, but also by a ventral mesentery to the ventral wall of
the body. In later stages, it is obvious that no ventral mesentery
exists, for the pericardial sac is not divided, and it is asserted

Fie. 2.

that this undivided condition of the pericardium is due to the
disappearance of the ventral mesentery.

It may be stated at once, after the above account of the
very general belief which exists regarding the early stages of
the development, that the phenomena described do not occur,
for they would necessitate that the ventral wall of the body
from the umbilicus to the mouth is, at some period, cleft in the
middle line, and that the cleft only disappears as the two lateral
folds converge and separate the foregut from the remainder of
the blastodermic cavity. In no vertebrate is any such condition
found. The ectoderm and entoderm of the anterior part of the
' ventral wall of the body, the part in front of the umbilicus, are

4 PROFESSOR ARTHUR ROBINSON.

never cleft in the middle line; but the mesoderm, which is a
later formation, enters this section of the body in a different
manner and at different periods of development in various groups
of animals. In this respect, the anterior part of the ventral
wall of the body, the part in front of the umbilicus, differs
essentially from the posterior part, the part behind the um-
bilicus, for the former is developed from the portion of the
ovum which lies in front of and below the blastoporic region,
and the latter is formed from the primitive streak which repre-
sents the closed blastopore. The anterior part, therefore, was
never cleft mesially, whilst the posterior was; and the latter may,
and, not uncommonly, does revert to its open condition, such re-
opening resulting, in certain cases, in extroversion of the bladder.
It is the want of appreciation of these facts, combined with a
false idea regarding the mode of formation of the folds of the
embryo, which has led to the incorrect descriptions of the
formation of the pericardium in mammals, for in these
vertebrates the pericardium is never separated into right
and left halves by a ventral mesocardium; indeed, in
them a ventral mesocardium does not exist; and although
it is present in other groups, it is not formed in the manner
usually described.

Before the early stages of the development of the pericardium
in mammals can be properly appreciated, its formation in other
vertebrates must be investigated, and at the outset of this
investigation it is necessary to obtain a clear idea of the
relationship of the embryo to the ovum, and of the origin,
extension and differentiation of the mesoderm.

As regards the relationship of the embryo to the ovum,
vertebrates are divided into two great groups, those in which the
ovum becomes the embryo, as in Amphioxus and amphibians,
and those in which only part of the ovum becomes the embryo,
the remainder being utilised in the formation of nutritive and
protective membranes and appendages, as in reptiles, birds and
mammals. ;

In the simpler forms of vertebrates in which the ovum
becomes the embryo, the formation of the pericardial region
takes place in the least complicated manner.

In Ampuioxus the unilaminar organism which results from *

:

HARLY STAGES OF DEVELOPMENT OF THE PERICARDIUM. 5

the segmentation of the ovum is converted into a bilaminar in-
dividual by invagination, and the invagination cavity becomes
the alimentary or enteric cavity of-the embryo. The aperture
which leads into the enteric cavity is the primitive mouth or
blastopore; it becomes elongated from before backwards, and
immediately below its margins a series of pocketlike diverticula
are projected outwards into the remains of the segmentation
cavity. These diverticula are the rudiments of the mesoderm
(fig. A), and the cavities contained within them are the rudiments
of the ccelom or body cavity. The diverticula gradually grow
towards the ventral aspect of the embryo, and finally they meet
beneath the ventral wall of the alimentary canal, where the
adjacent walls of the ccelomic rudiments of opposite side fuse
together and form, for a time, a mesentery. In the dorsal part
of this mesentery a subintestinal blood-vessel is developed, which
represents, in the anterior part of its extent at least, the heart
of the higher forms. Therefore in Amphioxus the representative
of the heart of the higher vertebrates is connected with the
ventral wall of the body by a ventral mesentery, which exists for
a considerable time.

In Ampuipia the process of invagination and the formation
of the blastopore and enteron are more complicated than in
Amphioxus, and the mesoderm is formed simultaneously with
the entoderm. Ultimately, however, it is delaminated from the
entoderm, and cleft into outer and inner layers, by the appearance
within it of the ccelomic space. Asin Amphioxus the mesodermal
sheets of opposite sides meet together beneath the ventral wall of
the alimentary canal, where they form for a time a mesentery
(figs. B and C). Beneath that part of the alimentary canal
which afterwards becomes the pharynx the heart appears in the
dorsal border of the mesentery, and the ccelomic spaces in its
immediate neighbourhood become converted into the pericardium.
In the early stages, therefore, in the tadpole, the two halves of
the pericardial section of the ccelom are separated from each
other by the ventral mesentery which connects the heart with
the ventral wall of the body.

In ReEptiLes, Birps, AND MAMMALS, the processes of develop-
ment are much more complicated, for the ovum is no longer
utilised for the formation of the embryo alone, but also for the

6 PROFESSOR ARTHUR ROBINSON.

formation of a series of membranes and appendages, which are en-
dowed with protective and nutritive functions, and the two parts,
though they are merely segments of one continuous surface, are
soon differentiated from each other, so that at a very early period
of development it is possible to recognise an embryonic and a
non-embryonic section of the ovular surface. The margin of the
embryonic section is clearly defined, and from the time of its
appearance to the end of life it can always be easily recognised,
for it is the margin of the umbilical orifice, which increases until
birth, and then is only reduced by a process of cicatrisation, for
it is obvious that the diameter of the embryonic area of the ovum
is much smaller than the diameter of the umbilical orifice of the
adult body. Therefore the orifice is not reduced in size during
the early stages of development by the convergence of its
margins towards a central point. This being the case,
no tucking off of the embryo from the surface of the ovum
can occur; on the contrary, what does occur is almost the exact
opposite of such a process, for the margin of the area remains as
a relatively slow-growing region, whilst the embryonic and the
extra-embryonic portions of the wall of tle ovum rapidly inerease
inextent. Under these circumstances, it follows that the margin
of the embryonic area will soon appear as a ring between the
upper or embryonic and the lower or extra-embryonic parts of
the ovum, both of which have expanded beyond it in all
directions.

In the consideration of the development of the pericardium,
the embryonic region alone requires further study, and it becomes
necessary to inquire into its mode of growth, but before this can
be appreciated, the positions of certain sections of the embryonic
region must be defined.

The embryonic area is at first circular, then ovoid, and finally
pear-shaped (fig. D). The narrow end of the pear-shaped area
is posterior, and upon it appears a linear thickening, the primitive
streak. In front of the primitive streak the neural folds are
formed ; their posterior ends embrace the anterior part of the
primitive streak; and their anterior ends unite together some
distance behind the anterior end of the embryonic area. In the
meantime the mesoderm has extended from the sides and posterior
extremity of the primitive streak, which represents the fused lips

a

EARLY STAGES. OF DEVELOPMENT OF THE _PERICARDIUM. 7

of the blastopore of Amphioxus, throughout the embryonic and

“ extra-embryonic areas, except in certain regions which vary in
extent in different classes of vertebrates and also in different

groups of each class. For purposes of the present study, it is
permissible to take an imaginary form in which it may be
supposed that the mesoderm has extended over ‘the whole area
of the ovum between the two primitive layers, except in the
middle line of the embryonic area below the mesial axis of the
neural groove, and in a small area, for which I have proposed the
term bucco-pharyngeal membrane, which is situated in front of
the neural groove, and which afterwards becomes the septum
between the primitive mouth and the primitive pharynx. It
may also be supposed that the mesoderm has become cleft into
an outer and an inner layer, except along the margins of the
neural groove on each side, where the outer and inner
layers are continuous with each other (figs. J, K, L, M, N).
Turning again to the embryonic area, it must be noted that the
anterior portion of the region which is situated between the
bueco-pharyngeal region and the anterior margin of the area is
the part which will ultimately lie immediately in the anterior
boundary of the umbilical orifice; it is therefore the region in
which the pericardium will be developed, and may be termed the
pericardial area.

_ Inthe early stages the pericardial region occupies the most
anterior part of the embryonic area, and in the imaginary
specimen under consideration it consists of the four usual
layers of the germ—two outer layers, the ectoderm and the
somatic mesoderm ; two inner, the entoderm and the splanchnic
mesoderm ; and between the somatic and splanchnic mesoderm
there is a portion of the ccelom or body cavity (figs. K, L).
The main blood-vessels of the embryo have in the meantime
commenced their development, and they form two longitudinal
trunks, one on each side, which pass backwards in the splanchnic
mesoderm from the vascular area on the wall of the yolk sac
in front of the embryonic area to the vascular area behind the
embryonic region; and the vascular circle on each side is com-
pleted by the capillary vessels of the vascular area, through
which the blood is returned from the posterior to the anterior
end of the germ. At this period, therefore, in this imaginary

8 PROFESSOR ARTHUR ROBINSON.

embryo, the main blood-vessel on each side would pass back-
wards in the splanchnic mesoderm which forms the lower or
ventral boundary of the pericardial section of the ccelom (figs.
J, K, L).

The first change of importance which takes place in the
further development of the pericardial section of the embryo is
its reversal, or the alteration of the positions of its extremities
and surfaces, the primitive anterior boundary becoming the
posterior, and the original ventral surface becoming the dorsal
surface (figs X, Y, Z, Z,). As this change of position is due
entirely to the manner in which the embryonic area grows, it
becomes necessary to consider that growth more carefully ; and
when embryonic areas of gradually increasing size are carefully
examined, it is found that the rate of growth varies considerably
in different parts of the area, and that the antero-posterior
increase is more rapid than the transverse. It is in the
region of the anterior end of the primitive streak that the
most rapid antero-posterior growth occurs, and this section of
the embryonic area constitutes a kind of nodal point. It
follows, therefore, that as the margins of the embryonic area are
comparatively stationary, whilst the region within the margins
is rapidly growing, that the area must fold, and folding, it might
project inwards into the interior of the ovum, forming a hollow
invaginated tube; or upwards from the ovular surface; or for-
wards, backwards, and laterally over its own margins.

The folding inwards or invagination does actually occur in the
very early stages of development of rats, mice, squirrels,
guinea-pigs, and apparently, to a slight extent, in the human
ovum, producing what is known as the inversion of the layers.
The upward folding does not occur, being prevented by the walls
of the cavity in which the ovum lies, but the peripheral
folding occurs in all animals as the embryo is gradually moulded
into form, and the preliminary inversion, if it has occurred,
disappears. Thus it becomes evident that there is no tucking
inwards of the margin of the embryonic area; on the contrary,
the head, tail, and lateral folds, which appear as the embryo |
gradually assumes its form, are due to the relatively stationary
condition of the margin of the area and the rapid increase of
its surface extent, the two factors combined necessarily giving

EARLY STAGES OF DEVELOPMENT OF THE PERICARDIUM. 9

rise to a folding of the area. Further, as the embryonic area
increases in size it also increases in weight, and the increased
weight causes it to sink into the interior of the ovum, thus pro-
_dueing around it a second series of folds of the extra-embryonic
portion of the ovular surface which constitute the amnion folds.
As the amnion folds have no bearing upon the development of
the pericardium they need no further consideration, but the
folds of the embryonic area have a direct bearing upon the
subject of this study, and they require, therefore, more detailed
investigation.

It has already been stated that the antero-posterior increase
of the embryonic region is more rapid than the lateral increase,
and this is soon rendered evident by the preponderance of the
head fold over the lateral body folds (figs. X, Y). During the
development of the head fold the anterior margin of the em-
bryonic area remains relatively stationary, and the anterior end
of the neural groove passes rapidly forwards till it projects well
above and beyond the anterior end of the area. As this pro-
jection occurs, the posterior ends of the bucco-pharyngeal and
pericardial regions are pushed forwards, and ‘their surfaces are
necessarily reversed. When the alteration of position is com-
pleted, what was originally the ventral surface of the pericardial
region has become the dorsal surface, and it forms the ventral
wall of the foregut, which is the portion of the blastodermic
cavity carried forward into the embryo during the formation of
the head fold (fig. X). The foregut, therefore, lies entirely within
the head fold, and consequently the formation of its ventral wall
cannot in any way be due to the convergence and fusion of
lateral folds. In the imaginary embryo at present under con-
sideration it is obvious that, after the formation of the head
fold, the two main blood-vessels which passed backwards into
the embryo from the anterior part of the vascular area must
now ascend in the anterior boundary of the umbilical orifice
and turn forwards in the splanchnic mesoderm of the dorsal
boundary of the pericardial section of the ccelom to the lower
end of the bueco-pharyngeal region, and that they will ascend
from the pericardial region in the rudimentary mandibular
arches which are developing along the lateral margins of the
bueco-pharyngeal area to the under surface of the head (fig. X),

10 _ . ‘PROFESSOR ARTHUR “ROBINSON.” »

where they will turn backwards, towards the ¢audal region of the
body of the embryo, under the paraxial mesoderm at the sides of
the neural tube, which has been formed in the meantime by
the incurvation and fusion of the margins of the neural groove
(fig. Z). Subsequently, the two primitive vessels fuse together
in the splanchnic mesoderm of the dorsal wall of. the pericardial
portion of the celom and project downwards into. the cavity,
being suspended from the dorsal wall by a mesocardium:
posterius, but it is perfectly obvious that under the conditions
defined no ventral or anterior mesocardium can be produced,
and that the pericardium is not formed by the convergence of
cceelomic spaces which lie in the lateral folds and their fusion in.
the ventral middle line, but that it is produced by the inclusion.
of the anterior portion of the ccélomic space in the body. as
the head fold is projected forwards in association with the rapid
antero-posterior increase of the embryonic area. *
So far, however, only an imaginary ovum has been considered,
in which the primitive blood-vessels occupy what may be
considered to be their original positions and form two vascular
circles, one immediately to either side of the middle line, both
in the embryonic and the extra-embryonic portions of the ovum.
This simple condition no longer exists, if indeed it was present
at any time, either in reptiles, birds, or mammals, and the modi-
fications of it which appear in all three groups are associated |
with differences in the rate of extension of the mesoderm
between the two primitive layers, and to differences in its rate
of cleavage into somatic and splanchnic portions. These
differences are, in their turn, associated with modifications of
pericardial development which are of considerable interest, and
which have been very imperfectly described. :
Reptiles and birds do not differ essentially from each other so
far as the peculiarities of mesoderm extension are associated
with the early stages of the formation of the pericardium, and
birds, therefore, may be used to illustrate the phenomena which
are of importance, inasmuch as they are more easily obtainable,
and their development is better known than that of reptiles. —

Birrps.—

In birds, as in mammals, the mesoderm extends from the

EARLY STAGES OF DEVELOPMENT OF THE PERICARDIUM. 11

a

sides and posterior end of the primitive streak, and not only
does it leave the notochordal and bucco-pharyngeal portions of
the embryonic area uninvaded, but also, for a considerable time,
a large area which extends forwards and outwards from the
bueco-pharyngeal region well into the extra-embryonic part of
the ovum in front of the embryonic area (fig. D). The em-
bryonic portion of this mesoderm-free region is that in which
the pericardium will afterwards be developed, and the extra-
embryonic portion subsequently becomes bent over the head of
the embryo as the anterior amnion fold, which is known as the
proamnion because it consists only of ectoderm and entoderm,

_ whilst a true amnion fold is formed by a fold of the somatopleure,

that is by a layer of ectoderm lined internally by a layer of somatic
mesoderm. Clearly, therefore, as the primitive blood-vessels are _
developed in the splanchnic mesoderm, they can only pass from
the anterior part of the vascular area round the margins of the
proamnion and along the sides of the bucco-pharyngeal area into
the embryo, and in the early stages no blood-vessels are present
in the pericardial region of the ovum. At a later period the
mesoderm extends both into the pericardial region and into the
proamnion, and cleaves as it extends, but before this occurs the
head fold is formed by the rapid antero-posterior increase of the
embryonic area, and thus for a time, in birds, the whole of the
ventral wall of the foregut consists of ectoderm and entoderm
alone (fig. E). Subsequently, the two layers of the mesoderm,
inclosing between them the ccelomic space, sweep into it from
the sides, carrying with them the rudiments of the heart, which
thus eventually lies in the ventral wall of the foregut, and is
connected dorsally with the wall of the gut by a dorsal meso-
cardium, and ventrally with the ventral wall of the body by a
ventral mesocardium (figs. G, H). In birds, therefore, as in
amphibians, a ventral mesocardium is present; nevertheless,
only the mesodermal portion of the ventral wall of the foregut
is formed by the ingrowth and fusion of lateral folds. The
ectoderm and entoderm belong entirely to the primitive head
fold, and they are at no time cleft or separated into lateral
halves in the ventral middle line. The mesoderm alone, on
account of its peculiar mode of extension between the primitive
layers, is cleft mesially, and it does not enter the region of the

12 PROFESSOR ARTHUR ROBINSON.

ovum which becomes the ventral wall of the foregut until the
head fold has been formed.

MaAmMMALS.—

In mammals, either on account of the smaller size of the ovum
or on account of the more rapid extension of the mesoderm, the
latter layer has extended through the pericardial section of the
embryonic area, and is cleft into somatic and splanchnic layers
before the head fold is formed, and in the earlier stages the
pericardial mesoderm of these animals forms a crescentic mass,
bounded in front by the anterior margin of the embryonic area
and the posterior margin of the proamnion, if the latter is
present, and behind by the bucco-pharyngeal membrane, whilst
postero-laterally it is continuous with the general mass of the
mesoderm, both of the body of the embryo and of the extra-
embryonic area, at the level of the posterior part of the bucco-
pharyngeal membrane (figs.O, P). In man, where apparently no
proamnion is formed, and in some rodents where the proamnion is
a very small and transitory structure, the mesoderm of the peri-
cardial region is in close association, at the anterior border of
the embryonic area, with the more anteriorly situated extra-
embryonic mesoderm, but the two portions are always definitely
separated by a cleft, and in these mammals, as in those which
are provided with a comparatively large proamnion, the only
connection of the pericardial with the non-pericardial portion of
the mesoderm is situated posteriorly, on each side, at the level
of the posterior part of the bucco-pharyngeal membrane. Why
this separation of the anterior border of the pericardial meso-
derm from the adjacent extra-embryonic mesoderm persists at
the anterior border of the embryonic area in those animals in
which no proamnion is present is not clear, and it can only be
looked upon as an indication of the descent of the animals in
question from proamniotic ancestors.

In mammals provided with a proamnion it is obvious that, as
in birds, the blood-vessels passing from the anterior part of the
vascular area to the embryo must run along the margins of the
proamniotic membrane, and then turn forwards in the splanchnic
mesoderm of the pericardial tube towards the anterior end of
the embryonic region, where they turn backwards along the

EARLY STAGES OF DEVELOPMENT OF THE PERICARDIUM. 13

= of the bucco-pharyngeal membrane, and pass to the posterior
_ end of the embryo beneath the paraxial mesoderm of the head
and body (figs. O, R). At the posterior end of the embryonic
area they enter the posterior part of the vascular area and join
a the capillaries, by means of which the vascular circle on each
_ side of the ovum is completed, and they run a corresponding
course in mammals in which the proamnion is rudimentary.
As the head fold develops, the posterior end of the peri-
cardial region is swung forward, the surfaces of the region are
reversed, and it is carried into the ventral wall of the developing
foregut, consequently the two primitive blood-vessels of the
embryo, which previously ran backwards from the anterior
border of the pericardial region to the sides of the bucco-
pharyngeal membrane, now run forwards from the posterior part
of the reversed pericardial region to the lower border of the
reversed bucco-pharyngeal membrane, and they lie close together
in the dorsal wall of the pericardial cavity, attached to the
ventral wall of the foregut by a dorsal mesentery, but their
ventral surfaces are free, and quite devoid of a ventral meso-
cardium (figs. 8, T).
At this period the fused somatic and splanchnic mesoderm of
the anterior margin of the umbilicus, the original anterior border
_ of the pericardial region, is undergoing rapid proliferation, and it
forms the mass of mesodermal tissue, the septum transversum,
___ from which the posterior wall of the pericardium and the central
_ part of the diaphragm are afterwards differentiated. At the
lateral margins of this mesoderm lie the lateral cornua of the
pericardial tube, which form two small canals situated at the
_ sides of the foregut in the anterior boundary of the umbilicus
(fig. V), and in the inner and lower boundaries of these tubes,
in the septum transversum, lie what were the anterior extremities
of the primitive blood-vessels of the embryo, which have now
become the vitelline veins. They ascend from the yolk sac into
the lateral part of the anterior boundary of the umbilicus, and
then pass forwards through the septum transversum at the sides
of the posterior part of the foregut to the posterior part of the
heart, for by this time those parts of the primitive blood-vessels
which lie in the dorsal wall of the pericardium are fusing to
form the single tubular heart (fig. W). It is the relation of the

14 ae. -. PROFESSOR ARTHUR ROBINSON. -

lateral cornua of the pericardial tubes to the wall of the foregut
at this period which have given rise to the erroneous descriptions
of the completion of the ventral wall of the foregut by the fusion
of the ventral ends of the lateral folds of the body wall, and of
the formation of the pericardium by the union in the ventral
middle line of the portions of the ccelom which lie in each lateral
fold, such fusion necessarily producing, ‘as in birds, a ventral
mesocardium, which disappears when the two halves of the peri-
cardial cavity bécome continuous. The figures which are
supposed to substantiate this interpretation of the formation of
the pericardium are simply figures of sections which pass through
the anterior boundary of the umbilical orifice, and therefore
through the primitive septum transversum and the lateral cornua
of the pericardial space, which may be called the pleuro-pericardial
canals (fig. V), as they afterwards communicate for a time with
the pleural sacs which are developed at the sides of the foregut
and dorsal to the pericardium, coincidently with the development
of the neck and the forward migration of the visceral arches; but
as these processes are associated with the later stages of the
development of the pericardium, er cannot be considered in
the present communication.
Finally, it must be noted that the pericardial region of the
embryonic area is limited anteriorly, in the early stages, by the
anterior border of the embryonic area, which becomes the anterior
boundary of the umbilicus, and that, as the pericardial region is
reversed during the formation of the head fold, the pericardium
expands so rapidly that for a time it projects backwards beyond
the ectoderm at the anterior margin of the umbilicus, and lies
between the foregut and the yolk sac, as in the ferret
(figs. AA, BB). As development proceeds, it gradually assumes
a more anterior position, and eventually lies between the fore-
gut and the ventral wall of the body, in front of the umbilical
orifice. It assumes its permanent position coincidently with
the formation of the neck-and the ascent of the auricles to the
dorsal wall of the aortic bulb, but even under these circumstances
there is no ventral mesocardium.

EARLY STAGES-OF DEVELOPMENT OF ‘THE PERICARDIUM. 195
Aig Peer emetic! !
sisiciaaee|

ty. In AMPHIBIANS the pericardium i is formed by the fusion of
cag Me anterior parts of the lateral halves of the, ccelom in the
ventral middle line beneath the anterior part of the foregut, and
a ventral mesocardium is present for a time.

(2) In Birps the pericardium is formed after the development
iiths : head: fold by the ingrowth of’ the lateral parts-of the
celom into the ventral wall of the foregut: and their fusion in
‘the middle line... The rudiments of the heart lie along the
‘dorsal part of the line of fusion, and for a time ‘a ventral meso-

ium is present.

~ (3) In Mammats the paracdink mesoderm, is ‘present i in the
pericardial portion of the embryonic area, and it is completely
separated into somatic and splanchnic layers before the head
fold appears ; there is therefore a single pericardial cavity which
extends from side to gide ale the anterior boundary of the
oo area. —

As the head fold forms, the pericardial region is reversed,
aa it is carried into the ventral wall of the foregut, where it
forms a U-shaped tube, which communicates at each end with
the general coelom.

The rudiments of the heart are formed in the splanchnic layer
ee the pericardial mesoderm ; therefore, after the reversal of the
area, they lie in the dorsal wall of the pericardial space, attached
-by a dorsal mesentery to the ventral wall of the foregut, but they
are never, at any time, connected with the ventral wall of the
pericardium by a ventral mesocardium.

FIGURES.

| (A)—diagram of the blastodermic layers in Amphioxus, showing
the relation of the mesoderm to the primitive ranges sags blood-
vessel.

(B)—transverie seibticin of a tadpole, showing the formation of the
two halves of the pericardial portion of the ceelom and the ventral
cardiac mesentery.

(C)—transverse section of an older tadpole, showing that the

i a Ml ee te a ee

16 PROFESSOR ARTHUR ROBINSON.

ventral cardiac mesentery disappears, and that the two halves of the
pericardial portion of the ceelom fuse together.

(D)—diagram of a portion of the upper part of the ovum of a bird,
showing the areas which are devoid of mesoderm and the positions in
which the primitive blood-vessels will develop.

(E)—diagram of a lateral longitudinal section of the ovum of a
bird, immediately after the formation of the head fold, and before the
mesoderm has entered the pericardial area.

(F)—diagram of a transverse section through the embryonic portion
of the ovum of a bird, along the line a in fig. E,

(G)—diagram of a lateral longitudinal section of the embryonic
portion of the ovum of a bird, after the pericardial portion of the
coelom has extended into the embryonic area.

(H)—diagram of a transverse section of the embryonic portion of
a bird’s ovum, along the line a in fig. G.

(J)—diagram of an imaginary ovum, in which the mesoderm has
extended through all parts except the floor of the neural groove and
the bucco-pharyngeal region,

(K)—diagram of a lateral longitudinal section through the
imaginary ovum represented in fig. J.

(L), (M), and (N)—diagrams of transverse sections of an imaginary
ovum, along the lines a, 6, and ¢, fig. J.

(O)—diagram of a portion of the upper part of a mammalian ovum,
showing the mesoderm-free areas and the courses of the primitive
blood-vessels,

(P)—diagram of a lateral longitudinal section through the ovum
shown in fig O.

(Q)—diagram of a transverse section along the line a in fig. O.

(R)—diagram of a side view of a mammalian ovum, showing the
positions of the various areas and the course of the primitive blood-
vessel on the left side.

(S)—diagram of a side view of an older mammalian ovum, showing
the alterations in the positions of the pericardial and bucco-pharyngeal
regions, and the corresponding portions of the primitive vessels. The
formation of the amnion folds on the lower or extra-embryonic part of
the ovum has been omitted.

(T)—diagram of a longitudinal section of a mammalian ovum after
the formation of the head and tail folds of the embryo and the forma-
tion of the amnion folds.

(U), (V), and (W)—diagrams of transverse sections of a mammalian
ovum along the lines c, b, and a respectively in fig. T.

(X)—diagram of a lateral longitudinal section of an imaginary
ovum, similar to that shown in fig. K, but after the formation of the
head and tail folds, showing a continuity which never actually exists

Journ. of Anat. and Physiology, Oct. 1902.)

—

‘< :
= «aoe *
rao S *

eee

>

= aol are ~
Q
.

PROFESSOR Roprnson.

[Pate I.

3 Rian
ti v4
fe
‘ . .

‘ _ EARLY STAGES OF DEVELOPMENT OF THE PERICARDIUM.

the extra-embryonic ceelom immediately in front.

17

between the — pericardial mesoderm and the pericardial celom, and

(Y), (Z), and (Z), —diagrams of transverse sections through the
caus apa ovum shown in fig. X, along the lines c, 6, and a respec-

FE ego of a lateral longitudinal section of a ferret’s ovum,
showing the position of the pericardium after the formation of the
head fold ; it also shows that for a time it is bounded below by the

yolk sac.

(BB)—diagram of a transverse section of a ferret’s ovum along the
line @ in fig. AA.

A,

EN,
FCAA,

a

HC,

VOL. XXXVII. (N.S. VOL. XVII.) —OCT. 1902.

EXPLANATION OF FIGURES.

aorta.

amnion fold.

anal membrane.
blastodermic cavity.

bueco-pharyngeal membrane.

ccelom.

cardiac mesentery.
ectoderm.
embryonic area.
enteric cavity.
embryo.
entoderm.

first cephalic aortic arch.

foregut.
H, heart.
hindgut.

P,

YS,

notochord.

neural groove.

neural tube.

midgut.

pericardium.
proamniotic area.
primitive blood-vessel.

pleuro-pericardial canal.

pleuro-peritoneal space.
pericardial region.
primitive streak.
segmentation cavity.
somatic mesoderm.
splanchnic mesoderm.
stomatodeum.

yolk sac.

bo

THE EXTENT TO WHICH THE POSTERIOR SEGMENTS
OF THE BODY HAVE BEEN TRANSMUTED AND
SUPPRESSED IN THE EVOLUTION OF MAN AND
ALLIED PRIMATES. By Arruur Kezrru, M.D., F.R.CS.,
Lecturer on Anatomy, London Hospital Medical College.

IN this paper the author proposes to deal with a section of a
mass of evidence he has collected for a more accurate determina-
tion of the inter-relationships of the anthropoids, and of the
kinship of man to that group of Primates. The data given here
deal with the suppression vf caudal segments, the transmutation
of sacral to caudal, lumbar to sacral, and dorsal to lumbar seg-
ments, which have occurred in the bodies of that group of
Primates of which man and the anthropoids are the living repre-
sentatives. The evidence is sufficient to show that in the process
of the evolution of this group of animals there has been no
addition or suppression of segments in either the dorsal,
lumbar, or sacral regions of the body; it is only at the distal
end of the caudal series that suppression or addition may
take place. Further, it will be shown that the transmuta-

tion of a body segment, in the evolution of a species, takes
- place, not by a bound, but by the gradual addition of minute
variations.

That the bearing of the evidence of this section on the problem
of the origin of the Higher Primates may be quickly grasped, it
is necessary to state the working hypothesis which appears to
be justified by the whole evidence at the disposal of the author.
In the first place, he regards the Primates as divided into two
very distinct groups—those which carry the axis of the body in
a horizontal position—the Pronograde Primates, including the
cynomorphous apes of the Eastern and Western hemispheres ;
and those which carry the axis of the body in an upright position
—the Orthograde Primates, into which group fall the gibbon,

SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 19

_ orang, chimpanzee, gorilla, and man.* The pronograde primate
_ is certainly the earlier type; from it the orthograde was evolved,
_ probably near the commencement of the Miocene Period. The
earliest type of the orthograde primate of which we have any
knowledge is the gibbon; from the Hylobatian (gibbon) type of
orthograde primate have sprung what may be named—for tem-
porary purposes—the giant primates, of which type the orang,
the chimpanzee, gorilla, and man are the present-day repre-
sentatives. This type was certainly gigantic, compared to its
predecessors. The earliest giant-form we know is Dryopithecus,
a Miocene anthropoid.

It wili be thus seen that three well marked stages are recog-
e nised in the evolution of the highest primates—the pronograde
® stage, the orthograde stage, and finally, the giant stage. In the
sy evolution of the human stock from that of the arboreal giant
E primates, a fourth stage must be recognised whereby man, by
7 what means we know not, became adapted to plantigrade pro-
4 gression. The process of transmutation of the pre-sacral seg-
ments and suppression of the caudal began with the change
_ from the horizontal to the upright posture during the evolution
ae of the orthograde type from the pronograde. In all present-day
pronograde apes—and we may safely suppose the same to hold
true of their Miocene ancestry—the segmental formula is nearly
constant—26 pre-sacral, 5 sacral, and 6-50 caudal segments. In
the gibbon there are 25 pre-sacral segments; in man, the gorilla,
and chimpanzee, 24; and in the orang, 23, Evidently, on the
assumption of the upright posture there was an abbreviation
of the trunk by one segment, and in the evolution of the
giant primates still another segment was cut off from the pre-
sacral series.

1. The total nwmber of Segments as determined by the number of
vertebre.—The first point which required investigation was the
total number of segments found in the various genera of living

* It is now generally recognised that the anthropoids, in their natural habitat,
carry their bodies in an upright position, 7.¢. are orthograde. The misconception
of the older naturalists sprang from their regarding the anthropoids as ground-
walkers ; for this method of progression they are as little adapted as seals or sea-
lions. Instead of the terms pronograde and orthograde, my friend Mr P. Duncan,
now Financial Secretary of the Transvaal, suggested Pronorachitial and Ortho-
rachitial, but I have not used the terms.

20 vat DR ARTHUR KEITH.

Higher Primates, in order that data might be obtained to give a
clue to the number of posterior segments which had been sup-
pressed, The number of vertebrae was accepted as an index of
the number of segments, In the following table ra L.*) are
given the results of this investigation.

TABLE I.

Total Number of Vertebre.

A

29, 30. 31 32. 88 84 235. 86,

Specimens. Per ct. Perct. Per ct. Per ct. Per ct. Per ct. Perct. Per ct. Average.

Orang . . 30 S35.) 20) 608 TB eh ee: a ae a 30°8
Gorilla... 16 64. 20°. 388, °26*4 182. ee AS 31°2
Chimpanzee 31 95 384 19 22 Or SS oe 31°5
Mae fis 4e0186 MG Pes gerne: 5:5 72:2 20 hy aa 33°3
(Paterson)
Man 3 45 108 a Sreinicudes 528:- 85°68 0 ae nts 33
(Bardeen)
Gibbon . . 51 ee ton ts RES 24 12 12 6 33
Macacus, <3 aks Sasi gi aeo ease a aor PY re 33-49
Cynocephalus ... ee ee) aealeeeneets Rae ac .. 86-44
Semnopithecus.., ee: 2st Ee ESS PR tiae A ..» 58-60
Ateles se bel PPMP 2 SE ase hed :¥ .» =~ 60-62
Cebus see = sag 7) ua ae Re er eer ae sacs Lae

From Table I. it will be seen (1) that within each genus of
the orthograde primates there is a high degree of individual
variation: orangs are found with only 29 vertebree and gibbons
occur with 36; between those extremes the vertebral formule
of the gorilla, chimpanzee, and man form intermediate series ;
(2) that the process of suppression has affected the segments of
the orang most and the gibbon least; (3) man has retained a
larger number than any of the other giant primates, because,
with the assumption of plantigrade progression, the caudal verte-
bree assumed a new role in supporting the perineum. The extent
of individual variation is evidence of the instability of the
structure of the Higher Primates,

* The data of this and the following tables have been obtained from three sources
—(1) from publications by many authors ; (2) from personal dissections ; (3) from
the material in the museums of London, A full list of papers dealing with the
Anatomy of the Primates was published by the author in 1896 (see ‘‘ An Intro-
duction to the Study of the Anthropoid Apes,” Natural Science, 1896 ; also pub-

lished separately), A list of subsequent literature from which data have been
obtained is given at the end of this article.

SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 21

____ The number of segments in a typical pronograde ape, such as
the American Cebus or Asiatic Semnopithecus, is from 54 to 60
_ segments.. The primitive orthograde stock arose probably
____ from a pronograde ancestry with a corresponding number of seg-
ments; but, arguing from the condition seen in the genera
Macacus and Cynocephalus, it is very possible that the caudal
vertebre were already largely suppressed before the orthograde
posture was assumed. At least, the presence of a tail is incom-
patible with the orthograde posture. The number of vertebral
‘segments in the primitive orthograde stock was probably about
36, the largest number that occurs in the gibbon—the nearest
living representative of that stock.

With the assumption of the upright posture, the flexor and
depressor muscles of the tail become modified to form a muscular
pelvic floor. The tail of pronograde apes, even when only the
four or five basal vertebree remain, plays the part of a perineal
shutter. The caudal vertebre are amorphous and_ practically
functionless in orthograde apes.

2. The total number of Segmental Nerves, compared with the
total number of vertebra.

A forward transmutation of a vertebra is usually accompanied
by a corresponding transformation of every element of the body
segment to which it belongs. The last lumbar vertebra, for
instance, may take on, partly or wholly, the characters of a first
: sacral; the nerves, the arteries, the muscles of that segment
A usually undergo a corresponding movement to a corresponding
extent. This correlation does not hold good for all the individual
variations found in the human body, but it does hold true for
the majority of such instances, as may be seen from the observa-
tions of Bardeen. When, however, different genera of primates
are dealt with, a very close correlationship will be found between
all the elements of a body segment. This will be seen in the
correlation between the total number of vertebrae and spinal

nerves in the various members of the Higher Primates (see
Table II.).

—.
ee
Ean.
' Sa
¥

‘-s
.
E. ’

F-

er eee

J

= = tt alot aa
re = *

[ TABLE.

22 DR ARTHUR KEITH.

TABLE II.
Prono-
Orang. | Gorilla. | Chimp. Man. Gibbon. grade
/ ) Apes,
The average number
of vertebre, 30°8 31°2 315 83°38 33 55
|
The average number |
of spinal nerves, 28 29 80 | 31 31 33

In the evolution of the orthograde primates, the segmental
nerves have undergone a forward transmutation nearly equal to

ei
f _
«ane

i evewe*”

er

Fie. 1.—Diagram to show (I.) the point in the vertebral column at which
sacralisation of the vertebre commences in various genera of the Higher
Primates, and (II.) the central point of emergence of the great sciatic nerve
in the same genera,

that of the body segments (see fig. 3). On the other hand, sup-

UPR ey ee ee

SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 23

pression of caudal vertebre has little influence on the total’
_ number of nerves; pronograde forms have only two or three
pairs more than the gibbon, the most primitive of the ortho-

grade primates. In Ateles, owing to the specialisation of its
tail as an organ of prehension, 40 of the segments may carry
spinal nerves, but in the more common pronograde apes the
number varies from 32 to 34. |
3. The number of Pre-sacral Segments.—A certain number of
body segments are modified to give attachment to the limbs.
In pronograde apes the sacral segments are almost constant in
number and position, the vertebra of the 27th segment forming
the first sacral. With the assumption of the orthograde posture
and the shortening of the loins entailed by that change (see
fig. 4) there was evidently a transmutation forwards of a whole
segment, the last lumbar (26th) becoming wholly sacral in
character. The vertebra of the 26th segment became the first

sacral. At least in the gibbon, which may be accepted as a repre-

sentative of the primitive orthograde stock, seeing how closely
the present-day animal resembles its Miocene ancestor, the 26th
vertebra forms the first sacral. In the evolution of the giant
primates there was still a further transmutation forward of one
segment, the 25th becoming the Ist sacral. In the orang, for
reasons which will be given later, the transmutation has reached
the furthest point forward, sacralisation commencing at the
proximal border of the 24th segment. The data on which these
inferences are founded is given in Table III. In that table it
will be seen that the point at which sacral transformation occurs
in the segmental series is variable in each genus of the ortho-
grade primates. The genera dealt with in Table III. show sacral
transformation setting at every segment between the 23rd and
28th, the variations of one genus overlapping those of the next.

[Tass

24 DR ARTHUR KEITH.

TaBLeE III.

Vertebra forming t the 1st sacral.

23rd. 24th. 25th. 36th. 27th. 28th.
Per ct. Per ct. Perct. Per ct. Perct. Per ct. Average

Orangs. . . 46specimens. 54 77 17 4. ae es 23°1
Gorillas. . . 27 * 7°4 $7.0 66 BS re = 23°5
Chimpanzees . 38 “ 2°6 19°7 56°2 2293. -., bis 23°9
ee or... Sager ist 3 92 5 ie th 24°02
pe Pina eee 5 aia aah 8°5 85 52: Bates sea 23°9
Gibbons . . 59 =" és ah ASS ed Lap 24°9
Atelese . .. 6 3 ts ws) 0 OE ap Be 25
Macacus .. 19 a ape wa ste 45 53 2°38 25%
Cynocephalus. 8 vs a PC Eee 37°5 50 12 25°7
Semnopithecus 15 “a ay aes aa 4 96 si 25°9
ha meee | e ve joi kev he aie a 40 26°3

For the purpose of comparing the extent to which the hinder
lumbar segments have been affected by the process of sacral
transformation in each genus, it is necessary to take the average
point in the segment-series at which sacral transformation com-
mences. That point can be determined only to an approximate
degree. In the orang the point at which sacral transformation
commences in the average animal is a little below the proximal
border of the 24th segment (see fig. 1, A); sacralisation begins

nearly half a segment further back in the average gorilla; in the

chimpanzee and man the change commences near the distal
border of the same segment. In the negro, sacralisation
commences nearly one-third of a segment further back than in
white races. In the gibbon, sacral transformation begins near
the distal border of the 25th segment, rather more than a
segment further back than in the giant primates. In Semno-

pithecus, probably the best representative now living of the

early Miocene pronograde apes, sacral modification starts near
the distal border of the 27th segment—one segment further
back than in the gibbon.

Why should there have been a forward sacral transmutation

* These statistics are obtained from various authors, including Paterson, Rosen-
berg, Tenchini, and Papillaut.

+ Bardeen’s statistics. More than half of his observations were made on negroes
in whom the limbs are attached rather more than a third of a segment more poste-
riorly than in white men.

25

Fig, 2.—Diagram of a Gibbon (Hylobates lar), suspended by its arm to show the
adaptation of the muscles and trunk to its brachiating mode of progression
—(from a photograph).

26 DR ARTHUR KEITH.

of the body segments in the evolution of the orthograde and
giant primates? The reason is to be sought for in their adapta-
tion to a new form of locomotion. The long rod-like lumbar
region of the jumping and climbing pronograde ape becomes
unnecessary for an orthograde form like the gibbon, supported
more from its arms than on its legs (see fig. 2). In the evolu-
tion of the giant primates the pelvis became still more closely
knitted to the body, and the lumbar region correspondingly
shortened (fig. 4). On the evidence at present at his disposal,
the author believes that the evolution of the primitive ortho-
grade primates early in the Miocene Period was attended by the
addition of a lumbar segment to the sacral region; with the
evolution of the giant primates later in the Miocene, still
another lumbar segment was added to the sacral. It was
probably at the stage just mentioned at which the human
stock broke away from the common giant primate stock. The
assumption of plantigrade progression necessitated a longer
loin (fig. 4), which was evidently obtained by a suppression of one
pair, perhaps two, of ribs. The transformation of a third
lumbar to a sacral segment in the orang is probably a compara-
tively late acquisition following on its brachiating habits of
progression. While the upper extremities of the orang are
enormously developed, the lower limbs are comparatively small
and show many traits of degeneration. The upper half of its
body is developed at the expense of the lower half.

4. A forward progression in the origin of the great Sciatic
Nerve.—With the transmutation of the distal lumbar vertebre
into sacral there was a movement forward, although not to a
corresponding extent, of the points at which the nerve fibres
which form the great sciatic nerve make their exit (fig. 18).
The segmental nerves which contribute to the formation of the

great sciatic nerves in various genera of primates are shown in
Table IV.

2 SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 27

TABLE IV.

_ Spinal Nerves . 28rd. 24th. 25th. 26th. 27th. 28th. 29th. Lap
i Specimens. Origin.
Orang... 5 5 5 5 5 pa 24°5
Gorillas. . . 5 es 4 5 5 5 1 Ae 25°7
_ Chimpanzees . 6 ee 4 6 6 6 2 ee 25°8
Man (Eisler) 126 = i107 Tae | YO 194" 32 = 25°6

,», (Bardeen) 246 11 2238 246 246 245 157 35 25°9
Gibbn ... 9 sd 4 9 9 9 5 de 26°
Macacus. . . 10 aR len pie ARES Uy ela 1) ie 26°7
Semnopithecus. 18 nat te 1s. te" Te 3 me 26°2

In order to compare one genus with another, and the degree
of nerve and vertebral migration, it is necessary to fix a point
which marks the centre at which- the nerve fibres contributing
to the great sciatic make their exit. In the orang, in which the
seiatic nerve arises from the 23rd to the 26th, the central point
of its origin lies near the mid point of the 25th segment (see
fig. 1B); the central points of exit for the gorilla, chimpanzee, and
man lie on the 26th vertebra, in order from above downwards ;
on the proximal border of the 27th in the gibbon. LEisler’s
statistics place the central point for man above those of the
gorilla andchimpanzee ; Bardeen’s below them, probably because
his observations were made on the negro as well as the white
man. The central points of origin of the sciatic nerve in
Macacus and Semnopithecus, as shown in fig. 1B, are situated
on the 28th segment.

The observations which have been made on the anthropoids
are too limited in number to afford more than a rough approxi-
mation to the truth; but it is evident, considering the Higher
Primates as a group, that a transmutation of the nerve elements
of a segment has accompanied the sacralisation of the vertebre
(compare fig. 14 and fig. 18). In pronograde apes the central
point of origin of the great sciatic nerve and the point at which
sacralisation of the vertebra commences is situated in the 27th
segment; in the gibbon these two points are situated a segment
further forwards; but in the giant primates, sacralisation of
the vertebre starts a segment further forwards than the central
point of origin of the sciatic nerve.

_ It will be seen afterwards that the development of the costal

28 ms DR ARTHUR KEITH.

series influences the position of the origin of the sciatic nerve ;
in Semnopithecus and the orang, in which the origin of the
sciatic nerve is more proximal than one would expect, the costal
series have been abbreviated; in the gorilla and chimpanzee,
the costal series reach their full number, and in these animals
the central point of origin of the great sciatic nerve is more
distal than one would expect. In man, the origin of the great
sciatic nerve is also lower than is to be expected, and yet in him
the costal series has been reduced, and therefore, if the explanation
offered for the others is right, in him the origin of the sciatic
nerve ought to be high. The low position in man is probably
owing to the great development of his lower extremities.

It is evident that if such a transmutation of the hinder seg-
ments of the body has taken place during the evolution of the
giant primates, that the segmental distribution of the cutan-
eous nerves on the lower limbs must have been disturbed. In
pronograde apes, as we know from the classical researches of
Sherrington, the segmental distribution of the cutaneous nerves
is regular and symmetrical in the lower limbs, but such symmetry
and order have not been found in the segmental distribution of
the nerves in the lower limbs of man. The discrepancy is prob-
ably due to a disturbance which occurred in the forward trans-
mutation dealt with here. It is probable that the segmental
distribution of cutaneous nerves is not exactly alike in the
lower limbs of any two human bodies, and hence the discrepancy
in the results of different observers.

5. The number of Sacral Segments—Since it is the 27th,
28th and 29th body segments which undergo sacral modifica-
tions in the typical pronograde apes of the Western and Eastern
hemispheres, there can be little doubt that these were the sacral
segments in the pronograde stock from which the orthograde
was evolved. With the assumption of the upright posture in
the early orthograde primates, of which the gibbon is the best
living representative, the 26th segment underwent sacral modi-
fications ; with the evolution of the giant primates, still another,
the 25th, was added to the sacral segments; and still later, in
the stock of the orang, the 24th. Thus in the orang there
ought to be found six sacral vertebrae; in the gorilla, chimpanzee,
and man five, in the gibbon four, in pronograde apes three,

a ee gl ae ee ee
Ci 2 2 :

SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 29

Tee The annexed table (Table V.) will show how far this expectation
is well founded.

| TABLE V.
_ Number of Sacral "
, ara 2. 3. 4, 5. 6 i. 8

. Specimens. Average:
eo... 87 wd sa 12 24 1 ee is 4°7
Gorilla . . . 24 <a 3 1 13 5 1 1 5*1
Chimpanzee . 31 Gas 2 3 13 12 1 ae 5°2
Man (Paterson) 100 ae en 26 61°38 34:3 1°13 ... 5°3
», (Bardeen) 100 sy All BF BOG ETF S: At! 5°02
Gibbon. . . 68 tee 12 26 26 4 sat tke 4°3
BOs. . 8 si 1 2 he 7 ae os 3°6
Semnopithecus .- ... 3 a er i ius ax die -3
i reo GUMS Par. 2.3; he yes ee +3

On the average, the number of sacral vertebra answers to the
number expected. In the gibbon there are 4, in man, the

~ gorilla and chimpanzee 5, but in the orang there are less than

5, while 6 is the number to be expected. The reduction in the
number of the sacral vertebre in the orang is due, as will be
shown in the next paragraph, to a caudal transformation of the
posterior sacral segments. In pronograde apes only two verte-
bre articulate with the ilium, in orthograde there are three.
The gibbon, gorilla and chimpanzee show a greater instability
in the number of sacral vertebre than man, because in them it
plays a less defined and less important part in their locomo-
tion.

6. The caudal transmutation of the distal Sacral Vertebre.—
While the distal lumbar segments were undergoing a sacral
transformation, there was only a slight movement in the direc-
tion of turning distal sacral segments into caudal. In man
and the gibbon the first caudal vertebra is the 30th, and this
seems to be the primitive form, for in all the typical pronograde
apes the 30th is the first vertebra of the tail. In the orang
and gorilla, in which the forward transmutation of segments is
most marked, the last sacral (29th segment) has undergone a
caudal modification. As may be seen from Table VI., in which
the serial number of the vertebra forming the first caudal or
coecygeal is given, the extent of individual variation is very

great.

30 DR ARTHUR KEITH.

TABLE VI.
yartoticn forming ea 27th. 28th. 29th. 30th. lst. 32nd.
first caudal.

Specimens. Average.
Ve gees retat | | an 3 10 2 BF Be — 29
MTOM A i: 5) 5 AS 2 4 4 7 1 ae +29
Chimpanzee. . 31 2 8 3 15 3 ogy 29°3
Man (Paterson). 132 is a 3 103 24 2 30°2
,, (Bardeen). 104 te oe 6 89 9 ao 30
Gabbon’ s/s spc 48 ae is 12 19 12 6 3802

Occasionally in Macacus the 29th, and in Semnopithecus and
Cebus the 31st vertebra forms the first caudal ; but normally in
all three genera, the 30th forms the first of the caudal series.

7. The number of Caudal or Coceygeal Vertebrw.—The distal
sacral and all the caudal vertebre of the anthropoids are fre-
quently so vestigial in form that it is hard to say which is the
first caudal, and how many the caudal vertebre are in number.
It is probably owing to this difficulty that there is a discrepancy
in the statistics which are given relating to the orang. In that
anthropoid the 24th is the first sacral vertebra; there were, on
an average, less than 5 sacral vertebre; therefore the first
caudal ought to be the 28th and not 29th, as the statistics
show. Table VIL. too, is founded on a smaller number of
animals than Tables III. and V. In the following table (Table
VII.) the number of caudal vertebra in each genus is given.

TABLE VII.
Number of Caudal 9 3. ” 5. 6. 7.
Vertebre,
Specimens. . Average.
OAT Ge eee 4 12 2 3 3:1
Gorilla. . . 18 3 5 3 2 3°3
Chimpanzee . 32 5 12 5 7 3 37
yi
Man’. "> S804 9 95 Ft 3° (2)
Gibbon. . . 54 6 18 22 5 1 2 3°7
Semnopithecus .., ae We Fe a 7 ce 30
MACACIS: 35 os cas oe i Dae ops iis ae 4-21
Cynocephalus. .., io ae Pg ve ae ite 6-10

The most striking point relating to the caudal vertebre of the
anthropoids is their variability in number, and their amorphous

SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 31

and vestigial character. In comparison with these, the human

_ audal vertebre are steadfast in number and much better formed.
With the assumption of the upright posture in the primitive
orthograde primates, the tail became a useless structure and
underwent suppression. It was no longer required to play the
part of a balancing rod or perineal shutter. It is not improb-
able that the process of caudal retrogression had set in long
before the change in posture took place, for in many modern
species of pronograde apes belonging to the Macaque and
baboon genera, the typical number (30) of caudal segments is
reduced to 4 or 6, but in such cases of reduction the vertebree
still retain all the characters of fully developed caudal verte-
bre, still act as a perineal shutter, and in no way resemble the
amorphous remnants of the caudal vertebre in orthograde pri-
~ mates. With the change of posture there was a radical change
in the formation of the pelvic floor.

The adaptation of the tail as a prehensile organ, which has
led to many changes in the structure of South American apes,
is probably to be regarded as a comparatively recent acquisition.

8. The transmutation of Lumbar Segments as indicated by the
origin of the anterior crural nerve-—In the segmental origin of
the anterior crural or femoral nerve, evidence is to be found of
the degree to which the proximal lumbar segments have been
affected in the general forward transmutation that set in with
the assumption of the upright posture. The segmental nerves
which contribute to the formation of the anterior crural in
various groups of the Higher Primates is set forth in Table
VIII.

TABLE VIII.

Spinal Nerve.
ne Central

c i f
OE 6 SR OR 260) ROO geen

Specimens. Perct. Perct. Perct. Perct. Perct. Perct. Perct.
9 1 7 1 rae

Orang SG

Gorilla } eS 1 5 6 6 1 23
Chimpanzee. 11... 3 9 11 10 2 23
Man (Bardeen) 246 2 90 246 246 246 37 22°8
Gibbon é it Madey ea 1 10 11 6 23°8
Semnopithecus 10 ... ane 38 6 10 7 23°8
cee ak see ive 5 9 vne 241

32 DR ARTHUR KEITH,

In fig. 3 is shown the central point of origin of the
anterior crural nerve in each genus of the Higher Primates
dealt with here, and it will be seen by comparing the origin
of this nerve with that of the great sciatic that there is not a
close correlation between the forward movements of those two
nerves. The condition in Semnopithecus may be taken as
typical of pronograde apes, and in it the central point of origin
of the anterior crural nerve is situated near the distal border of
the 24th vertebra. In the orang the origin of this nerve has
moved forwards nearly two segments; in man, the gorilla and
chimpanzee, one’segment; but in the gibbon the pronograde
origin is retained. It will be seen presently that the origin
of the anterior crural nerve is correlated with the development
of the costal series ; with the retrogression of the distal ribs
there is a forward movement in the origin of this nerve. The
origin of the anterior crural is acted on by two influences: (1)
the forward transmutation of lumbar to sacral segments, and
(2) of the transformation of dorsal to lumbar.

9. The origin of the Obturator Nerve.—In the transmutation
of lumbar segments the obturator nerve does not follow closely
the migration of the anterior crural. In Table IX. are shown
the various segmental nerves which contribute to the formation
of the obturator.

TABLE IX.
Spinal Nerves.
21, 29. 98. 94. “35. 7aeoa eee
rc oe — Origin.
Specimens. Per ct. Per ct. Per ct. Perct. Per ct. Per ct.

Orang . ey eae ; Piet 7 Bie tare ws oe 22°3
Gorilla Te : ; Sealy Fy 5 6 6 1 ses 23°2
Chimpanzee. 4. . : Sp 3 4 3 es as 22°8
Man . . 246 (Bardeen) . 84 246 246 245 25 3s 22°8
Gibbon Ber be | : ; + Son 2a ee 7 cua 24°2
Semnopithecus 9 . : se 9 9 1 24°6
Macacus Ra: ‘ , cr vent eRe 1 7 8 4 24°7

In man the origin of the anterior crural nerve and obturator
is practically the same, the central point of origin for both being
the junction of the distal fifth with the proximal four-fifths of
the 23rd vertebra. In pronograde apes, on the other hand, the

SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 33
obturator nerve takes its origin at least half a vertebra behind

Semnopith. Macacus Gibbon Man Chimpanzee Gorilla Orang
| a
=z

Vv L ——
ng et Sa So Nerve
Mi oa *
wl an ee —-
T ¥sol___Vil
K beeen = ~~
x
Xt - -
xt
Xilt
lest stern. rib
xy lS Gee
xv!
XX 4 oy Jost uit
Fambat.___XX ——<— nerve & veces
xx! as BoP - b--- SSaLL eo ooo
Loan ab an: tl
Cia. News
—fObt. Nerve
Sad =e oe SS (Fteke q a= a fSac.tiext
x 7 ae 5s os me
Jatt = = ante £ a me = a
Sacral___Xv| “[——t___ Ce a
St in RE pa a oo
aaa —- = ee SSeeRE ane
Coccygeal XXX acezl, ’ I creel i
o 2 acs Lae veut.
‘wi a a feed - ~ 55 - - fee - a teet--- ~---
ey nia
Pee: TG iene: Sal Ra ze? ee ome
Xxx af Semen. = TE
vA

Fic. 3.—A composite diagram representing the vertebral columns, from the
4th to the 36th vertebrae, of various genera of Higher Primates. On each
vertebral column, founded on the statistics given in the text, are represented
the following points :—

(1) The central point of origin of the phrenic nerve.

(2) re - a brachial plexus,
(3) The segment carrying the last sternal rib.
(4) %? 9 9? rib.

(5) The point of origin of last nerve to rectus abdominis.
(6) The central point of origin of the anterior crural or femoral nerve
(7) The central point of origin of the obturator nerve.
(8) The point at which sacralisation of the vertebrae commences,
(9) The central point of origin of the great sciatic nerve.
(10) The point at which the vertebrae becomes candal.
(11) The point of origin of last spinal nerve.
(12) The last vertebra.

that of the anterior crural ; in the gibbon, orang and gorilla the
VOL. XXXVII. (N.S. VOL. XVII.) —OCT. 1902. 3

34 - DR ARTHUR KEITH.

origin of the obturator approaches, in the order named, the
origin of the anterior crural; in the chimpanzee, the origin of
the obturator appears to be slightly proximal to that of the
anterior crural.

10. The number of Rib-bearing Segments.—Owing to the lack
of evidence, it is a difficult matter to fix approximately the
number of rib-bearing segments in the primitive stock of the
orthograde primates. Even in typical] living pronograde apes
such as Semnopithecus and Colobus, there has been a suppres-
sion of at least one pair of ribs in the more recent, periods of
their evolution, so that in the matter of rib-bearing segments
these no longer represent the pronograde stock which gave rise
to the orthograde. From the evidence adduced in Table X., in
which the last rib-bearing segment is given in most of the
genera of the Higher Primates, it will be seen that the 8th to
the 21st segments are costal- bearing, making 13 pairs of
ribs,

TABLE X.

Last Costal-bearing Segment.
ad

172 9 00.

Specimens. Perct. Perct. Perct. Per ct. Perct. Per ct. Average.
Orang . AN RR ee piaae 4 87 9 #8 e 19°02
Man .— | . 104 (Bardeen) ... NE Set) ba te id BS Neo me me 18°9
Gorilla . eer gia ea es 10 = 84 6 va 19°96
Chimpanzee . 35° . =. ies = ra eee 7 ab 20°1
Gibbon . . 3838 ; ee a 9 82 9 “he 20
Semnopithecus 31. sae 3 94 3 ae ie 19,
Mavacus See : slices a 95 5... as yy 19°05
ynocephalus ...°- sheen vi +. 25° © -75- =e ie 19°7

Ateles . ater : wT hs 55: eS Kar, 100 Ae 21

Assuming that the 20th was the last costal-bearing segment
in the primitive stock from which the various genera of pri-
mates dealt with here arose, it will be seen that this number
has been approximately retained in the gorilla, chimpanzee and
gibbon. In the pronograde apes of the Eastern hemisphere the
number has been reduced, Cynucephalus suffering the least degree

* In 40 per cent. of these the 12th rib-was less than .two inches long, and
therefore could scarcely be regarded as forming part of the thorax.

SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 35

of suppression. It is probable that the number has been
increased in Ateles, and there appears to be a tendency to
f increase in the chimpanzee. -The fact that the diaphragm in
.s all the genera of primates mentioned in the above tables has an
a attachment to the rib or costal process of the 20th segment,
however vestigial that process may be, points to the fact that
the 20th segment has always been, as far as the Higher Primates
are concerned, the last of the respiratory segments.

It will be observed, too, that there is only a slight correlation
between the forward progression of the sacral segments and the
reduction of the distal. costal processes. The orang, in which
three lumbar have become sacral segments, has suffered reduction
in only one costal segment. The reduction in the number of the
costal segments in man, Semnopithecus and Macacus is due, not
to any retrogression in their respiratory system, but to an
elongation of the lumbar region of the spine rendered necessary
in those forms by their manners of progression.

11. Reduction in the number of Sternal Segments and Sternal
fibs.—In the suppression of the distal costal segments there
has been some reduction of the distal sternal segments, which
may be indicated, as shown in Table XI., by the number of
sternal ribs.

4
fae
%

[7

y
:
q
:
¥

TABLE XI.
os 6th. 7th. 8th. 9th. 10th.
’ Per ct. Per ct. Per ct. Per ct. Per ct. Average.
ROME 6 oe. 18 82 dis jut de 6°8
Man (white) . . 2 90 8 a Se ee y he’
CE) aire 70 30 a9 sea 7°3
Se 2 ay 2.8 85 10 ane ye 7
Chimpanzee . . ... 54 46 ies bi 7°4
CN ae 78 14 we te 7
Semnopithecus . 4 72 24 0 es 72
IS og ON ee 12 88 di ee 7°8
Cynocephalus . . ... we 60 40 ss _ 84
ET ee ieee fe 33 55 35 9

With some exceptions, the reduction in the number of sternal
ribs corresponds in a minor degree with the sacral transmutation
of the distal lumbar segments, and also with the reduction in
the total number of costal-bearing segments. The sternal ribs

36 DR ARTHUR KEITH.

are fewest in the orang, in which the forward sacral transmuta-
tion has proceeded furthest; the gorilla follows next; the chim-
panzee has a larger number of costal-bearing segments and
sternal ribs than any of the other orthograde primates. The
reduction in the number of sternal ribs in the gibbon has to be
sought for in the peculiar development and use of the pectoral
muscles (see fig. 2).

12. Transmutation in the distal, cervical and proximal dorsal
Segments——The proximal 18 segments of the body, compared
with those situated more distally, have undergone a very slight
degree of transmutation during the evolution of the various
genera of primates. In all the extant genera, as was no doubt
the case in the original stock of the primates, the 8th is the
first rib-bearing segment. Occasionally in man, the gibbon and
chimpanzee, the 7th cervical segment may take on partially or
even wholly the characters of the 8th; very rarely indeed is
there a backward transmutation when the 8th takes on the
characters of the 7th. The extent of the transmutation in this
region of the body may be measured by the central points of
origin of (1) the phrenic nerve, (2) the brachial plexus; and
although the data I have collected bearing on the segmental
origin of those two relate to a comparatively small number of
individuals, they are sufficient to show that, in the origin of the
brachial plexus and phrenic nerve, there is not, as shown
in fig. 3, half a segment of difference between the two most
extreme forms. The central point of origin of the phrenic
nerve is always at a point on the proximal half of the 5th
segment, that of the brachial plexus on the distal half of the
7th.

Occasionally, too, there is a partial occipitalisation of the first »
(cervical) body segment, the atlas being incompletely separated
from the occipital bone.

13. The last Segmental Nerve of the belly wall—An examina-
tion of the ventral aspect of the body reveals the fact that the
segmental abbreviation of the trunk has proceeded rather more
slowly on the ventral than on the dorsal aspect. The data on
which this statement is based is given in Table XII. There the
last nerve supplying the rectus abdominis is given in groups of
the Higher Primates.

TRANSMUTED AND SUPPRESSED IN EVOLUTION. 37

TABLE XII.
19th. 20th. ist. 22nd. 23rd.
Specimens. Average.
ae 4 1 ‘ds wR eh 19°2
4 2 1 1 19°7
267 44 214 9 19°8
7 a; 5 2 ta ee 20°3
11 7 3 1 = 20°4
3 2 1 os 21°38
6 4 2 es 21°38
3 = 22

: 14, Abbreviation of other structures—In comparing the level
at which certain viscera occur in the body, one must remember
hat most of the anthropoids dissected are young animals, and

he = of their viscera is comparable, not with those of

ion of the dehin the position of the arth of the aorta, ‘sod the
vel of the cricoid cartilage correspond in man and anthropoid.

listal lumbar segments. Thus the abdominal aorta bifurcates
at the level of the 24th vertebra in pronograde apes, or even at
4 | point situated more distally ; at a level with the 23rd vertebra
a in the gorilla, chimpanzee, gibbon and man; and at the 22nd in

“f j The spinal cord terminates at the 19th vertebra in the orang,
_ 22nd in the baby gorilla, 20th in the chimpanzee, 21st in man,
_ 22nd in the gibbon, 23rd in Macacus and Semnopithecus, and
24th in Ateles.
a 15, A comparison of the proportions of the cervical, dorsal and
lumbar regions of the spine.—In fig. 4 are represented diagram-
¢ eg the relative lengths of the cervical, dorsal and
4 _Tumbar regions of the spines in various genera of the Higher
_ Primates. The diagram is founded on measurements made
__ by Cunningham, the author, and other observers on several
____ Specimens of each genus. It will be seen at once that with the
___sacralisation of the distal lumbar segments there is also a
___ reduction in the relative length of the lumbar region. In the
orang, where the process has proceeded furthest, the lumbar
region is shortest, measuring only 24 per cent. of the pre-sacral

38 DR ‘ARTHUR KEITH.
part of the spine. The lumbar region is relatively longest in the
pronograde apes. Man occupies a curious position. At birth
the lumbar region is only 27 per cent. of the pre-sacral spine;
but as the child learns to walk, the lumbar region elongates
and becomes ultimately 32 per cent. of the spine, equal to that

of the gibbon. Thus at birth the proportions of the regions of

the human spine are those of an anthropoid. The short lumbar
region of the orang, as already explained—and the explanation is

Lambar

Cervical ; Dorsal
Orang ~ 262 ——— i
ay EE 1 a7
Baby we : a an
0 | ay
Chimp. 3 :
; 23| } 48) |) shat
Gorilla aS
| he 4 32
Gillon SB i
22|} ds 32
rf 727 42
Macacus cS aa
A $
: ZL AB
il mi e

Fic. 4.—Diagram to show the relative proportions of the cervical, dorsal, and
lumbar regions of the spinal column of the Higher Primates.

also applicable to the gorilla and chimpanzee—is owing to its
brachiating habit of progression. While its arms and the upper
half of its trunk are greatly developed, the lower half of the
trunk and lower extremities are small and out of proportion.
The cervical and dorsal regions of the spine retain practically

SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION. 39

_ the same relative proportions in all the orthograde primates.

The apparent shortness of the neck in pronograde apes is due
to the relatively long lumbar region.

SUMMARY.

With the evolution of the orthograde from pronograde
primates, the lumbar region becomes relatively shorter, the
process of abbreviation being brought about by the trans-
formation of the 26th (lumbar) segment to the Ist sacral;
in the evolution of the giant primates (the ancestral stock of
man, the gorilla, chimpanzee, orang), the lumbar region was
further shortened, the 25th segment becoming gradually sacral
in character. In the origin of the human stock, by the assump-
tion of plantigrade progression, the lumbar region again became
elongated, and it is possible that there may be in progress a
slight backward migration—a tendency for the 25th to again
become lumbar in character; but the fact that the point at
which sacralisation commences is situated more distally in the
negro than in the white man is against this assumption. In
the evolution of the orang the lumbar region was further
shortened, the 24th segment becoming sacral in character.
That is the working theory which I put forward to account for
the segmental arrangement of vertebre and nerves in the Higher
Primates.

_All the data given here support Rosenberg’s conception that
in comparing two animals, the 19th segment of one corre-
sponds to the 19th of the other, and the 20th to the 20th;
that one segment may assume one or all the characters of its
neighbour on either side; that suppression or intercalation of
segments has played no part in the evolution of the higher
mammals. It is certainly true that unilateral division of a
segment occurs; it is possible that the division may be occa-
sionally bilateral, but such a division is comparable to the
abnormal process of dichotomy that produces in the embryo a
double digit or a twin monster.

The extensive series of specimens in the Warren Museum in
Harvard University, described recently by Professor Dwight,

40 SEGMENTS TRANSMUTED AND SUPPRESSED IN EVOLUTION.

shows how every intermediate form occurs between the sacrali-
sation of the 24th and of the 26th segments, and that it is not
a matter of lifting out or inserting a segment, but the gradual
transformation of the characters of one segment into those of
the one lying next it in the series.

I gladly avail myself of this opportunity of acknowledging
my indebtedness to Dr Charles Hose of Sarawak, who, at
much personal sacrifice, has sent me an ample supply of
primate material.

REFERENCES.

BarRvDEEN, Cu. Russevt, and Ertine, ArtHur Wextts, “A Statis-
tical Study of the Variations in the Formation and Position of the
Lumbo-Sacral Plexus in Man,” Anat. Anzeiger, Bd. xix. pp. 124, 209,
1901.

BarbDEEN, Cu. Russe, “ Costo-vertebral Variation in Man,” Anat,
Anzeiger, Bd. xviii. p. 377, 1900.

Dwicut, Tuos., “A Description of the Human Spines, showing
Numerical Variation, in the Warren Museum of the Harvard Medical
School,” Anat. Anzeiger, Bd. xix. p. 321, 1901.

Paterson, A. M., ‘The Human Sacrum,” Soc. Trans. Roy. Soe.
Dublin, 1893, ser. 2, vol. v. pt. iii.

Paterson, A. M., “The Position of the Mammalian Limb,” Jour.
Anat. and Phys., 1889, vol. xxiii.

Cunnincuam, D. J., “The Lumbar Curve in Man and Apes,”
Cunningham Memoirs, Roy. Ir. Acad. Dublin, 1886, No. ii. pp.
1-148,

PapiLuavt, G., “ Variations numeriques des vertébres lombaires chez
Yhomme,” Bull. de la Soc. d’ Anthropologie de Paris, T. 9, ser. 4,
pp. 198-222.

TENcHINI, “ Costo-vertebral Variations in Eighty Bodies,” Archiv.
Ital. Biol., T, 12, p. 43, 1889.

RosENBERG, Emin, ‘“ Ueber die Entwicklung der Wirbelsiule,”
Morph. Jahrb., Ba. i. pp. 83-197, 1876. See also Bd. xxvii.

Rue, E., “ Zeugnisse fiir die Metamere Verkiirzung des Rumfes
bei Sdugethieren,” Morph. Jahrb., 1893, pp. 376-426.

Biruincnam, A., “ Variability in the Attachment of the Lower
saad s the Vertebral Axis in Man,” Jour. Anat. and Phys., vol.
xxv., 1891.

SOME CARDIOGRAPHIC TRACINGS FROM THE BASE
OF THE HUMAN HEART. By Astiry V. CLARKE,
M.D, Cantab., Physician to the Leicester Infirmary, and
J. SHotto C. Douatas, Christ Church, Oxford.

A waAIF male child, aged about 5, presenting the unusual
abnormality of congenital bifurcation of the manubrium sterni,

Photograph showing extent of the fossa. The lower marks on the skin
are the cheloid scars,

has recently been an inmate of the Leicester Infirmary. Owing
to§the rarity of this condition, the child is of great interest,

42 DR CLARKE AND MR J. 8. C. DOUGLAS.

because the beginnings of the great vessels, and probably the
base of the heart itself, are available for candianeeen tracings
in the human subject.

The child appears to be healthy in every way, the only other
abnormality being some cheloid scars situated on the skin
covering the depression where the manubrium ought to be.

The adjoining photograph shows the extent of the fossa, but
the following measurements were also made : es

Separation of the clavicles. — 24 in.
Length of fossa, i Big
Width of fossa—at top 2} in.
at second rib 1? in,
Depth of fossa, 2 in.
Length of sternum from imaginary top, 4 in.
Length of median piece, 1 in,
Sternal width, 1 in.

Pulsation of a strongly marked character, over an area of the
size of half-a-crown, is seen in the floor of the fossa during
tranquil respiration, but on deep respiration the edges of the
lungs become inflated and bulge into the fossa, rendering the
pulsation far less visible.

No tumour due to venous stasis appears at any period of the
cardiac cycle. .

X-ray observations were made to determine, if possible,
exactly what portion of the heart was presenting at the fossa,
but not with great success. A skiagraph is here produced when
the child is lying prone on the plate, and the margins of the
depression are outlined with wire, the nipples sia indicated
by metal pieces.

From this it will be seen that the abnormality does leave
some portion of the heart itself uncovered, and this observation
confirms the estimation of the position of the heart, as made out
by percussion of the deep cardiac dulness. The heart apex beat
being situated behind a rib, prevented tracings from being
obtained there. ;

The heart rhythm is normal, as also are the cardiac sounds.

Cardiographic tracings were taken by means of Marey’s
tambours, both when the child was awake and_ asleep, the

CARDIOGRAPHIC TRACINGS FROM THE BASE OF THE HEART. 43

former being attended with great difficulty owing to the rest-
lessness of youth. ;

Skiagraph showing relation of heart to the fossa.

The tracings are of intcrest, since it will be seen that a small
but very definite rise of the lever constantly takes place before
the great impulse which occurs on the opening of the aortic
valves.

ie
NEG UES hh np NYS
NUT
———_—>
Fie. 1.—To be read from left to right. Each division represents one-tenth of a

second,

The upper curve represents a tracing from the axillary artery; the lower
being obtained synchronously from the pulsating chest area.

At X the movements of the child caused the bottom of the tambour on
the axillary artery to slip off the vessel.

The portion of the curve A to D in fig. 1 gives the duration
‘of systole of the heart, since in our interpretation D is the

44 DR CLARKE AND MR J. 8. C. DOUGLAS.

dicrotic notch, while the small rise A B is due to that period of
systole which precedes the opening of the aortic valves, This
shorter period occupies about 1/10 sec. (when the child was
awake) to 2/10 sec. (during sleep),—and corresponds with the
well known observations as to the interval between the rise of
the intra-ventricular and intra-aortic pressures made by Chauveau
and Marey upon the horse. (Hiirthle, in the dog, found 1/50 to
1/25 sec., but in this animal the heart beats at a faster rate.)

Fic, 2.—To be read from left to right. The time is given in tenths of seconds.
The curve was obtained from the pulsating chest area while the boy was
asleep,

Discussing these tracings in more detail, we find from fig. 1
that the whole cycle of events takes from four to five tenths of
a second. The first portion of this time is occupied by a slight
rise of the lever, lettered in fig. 1 A to B, and this takes between
one and two tenths of a second. This initial rise is suddenly
followed by a very sharp ascent, viz., B to C; then follows a
gradual descent from C to A, which is interrupted by a slight
but constant wave D.

In this figure is also recorded a tracing of the axillary artery
taken synchronously (tracings could not be obtained from the —
carotids). From a comparison of the two tracings it will be seen
that the rise of the axillary lever occurs immediately after the
summit C of the tracing from the chest, that is, about 1/20 see.
after the point B. This interval of time would practically
correspond to the delay in the axillary pulse, such as would be
caused by the transmission of the pulse wave from the root of
the aorta to the axillary artery. From this interpretation of the
record the aortic rise of pressure begins at B, and hence the
portion A B of the lower curve (fig. 1) not being due to any rise
of blood-pressure in the aorta, must be caused by events occur-
ring during the systole of the heart. In our judgment it gives
the period elapsing from the commencement of systole to the
opening of the aortic valves. In larger mammals (Horse, etc.)
it has been shown that the time taken during the systole of the.

ee ea ee a ae

en oe

CARDIOGRAPHIC TRACINGS FROM THE BASE OF THE HEART. 45

__ heart in setting up an intra-ventricular pressure sufficient to open

the aortic valves is from one to two tenths of a second, and we

_ think that our own observations determine this time in the case

of the human heart, since A B is about 1/10 sec. in fig. 1 and
2/10 sec. in fig. 2. The portion of the curve BC A represents
the aortic pulse, D being the dicrotic wave; this aortic pulse
record in man is of interest, in that it has been obtained when
the viscera are in their normal position.

In fig. 2 we give a further tracing which was obtained during

2 3 + 4 4 re 4. 1

———

Fic. 3.—To be read from left to right. The time is marked in seconds. This
tracing was obtained from the pulsating chest area on a slowly moving
drum.

sleep, showing the same phenomena but spread over a slightly
longer period.

Fic. 4.—To be read from left to right. Time in seconds. Synchronous curves
of the pulsating chest area (above) and of the axillary artery (below).

Figs 3 and 4 are records on a more slowly moving drum, the
latter showing a tracing of the axillary artery synchronously
obtained.

All the tracings are reduced one-half.

In conclusion, we offer our thanks to Professor Gotch of Oxford
for his criticism, and also for the loan of the instruments used
for obtaining the tracings.

A STUDY OF THE CEREBRAL CORTEX IN A CASE
OF CONGENITAL ABSENCE OF THE LEFT UPPER
LIMB. By T. G. Moorneap, M.B., B.Ch., Chief Demon-
strator of Anatomy, Trinity College, Dublin. (PiatTE IIL)

In the volume of Brain for 1878 an account (1) of the cerebral
hemispheres of an individual whose left arm had been deficient
from birth was published by Sir William Gowers, and in the
volume of the same journal for 1880 an account (2) of a similar
case was published by Professor Bastian and Victor Horsley. In
both of these cases the ascending parietal convolution on the right
side was found to be of less extent than that on the left side
over an area which closely corresponded with the centres a, d, ¢,
d of Ferrier, while in neither of the cases was any inequality of the
ascending frontal gyri observed, and indeed in the former of the
two it was explicitly stated that these gyri were exactly equal on
the two sides. At the time when these papers appeared the views
of Ferrier regarding the localisation of arm movements in the
cerebral cortex were very generally received, and the appear-
ance of the brains in the cases referred to was held to afford
additional evidence in support of the experimental proof that
the centre for such movements was placed in the ascending
parietal gyrus. However, whilst advancing their case in support
of the view “ that there is a co-relation of some kind between the
functional activities of those regions of the ascending parietal
convolution and the movements of the opposite hand and
fingers,” Bastian and Horsley maintained that such a co-relation
might exist even though its commonly received explanation was
incorrect, and that before any definite conclusion could be drawn
from the examination of such cases more definite information
must be obtained regarding asymmetry of the ascending parietal
gyri in normally developed persons; and in the light of recent
discoveries the words may be regarded as almost prophetic.
Examination of the plates which accompany the two papers
shows that in the former of the two specimens there is without
doubt an obvious diminution in size of the ascending parietal

_ CEREBRAL CORTEX IN CONGENITAL ABSENCE OF LIMB. 47

us _ right side, almost exactly opposite the arm-centre
Sherrington and Griinbaum (3), but in the latter case the
_diminut ion in size appears to lie at a slightly lower level, the
g yrus being well developed opposite the arm-centre. In both
_ eases the arm-centre in the frontal gyrus is strongly developed
on each side, and the diminution in size of the parietal region is
_ only slightly, I believe, greater than is often met with in the
ea of normal persons.

_ Through the kindness of Professor Cunningham, Ihave
recently had an opportunity of examining the brain of an
adult man in whom the distal portion of the left upper limb
. 4 was congenitally absent. The photograph reproduced in Pl. III.
aa fig. 1, which was taken from a cast, shows the condition of the
arm, the five small projections immediately below the elbow
4 joint being the representatives of the undeveloped finger buds. .

__ The two cerebral hemispheres were well developed (PI. III.
fig. 2), and did not present any marked asymmetry in their
convolutions and fissures. The following measurements of the

_ transverse extent of the ascending frontal and parietal gyri were

_ Right Ascending Frontal. Left Ascending Frontal.

80 mm, 80 mm.
12°25 ,, 170
20°0 roo"
90 | oro ghee 875 2
10°75 ,, 160... ¢
I ie ip aig (1h So gee
Right Ascending Parietal. Left Ascending Parietal.
70 mm. 65 mm.
TAP 6 IOs,
10°25 _,, Opposite to 100.5%
i Arm-area. | 107i,
66"; 1 bey | Reese
11°5 ” 11-0 ”

- From these measurements it is seen that on the whole the

right side of both the ascending frontal and ascending parietal
gyri in the region of the arm-centre is smaller than the
corresponding area on the left side, the difference being more
marked, as a reference to the figure (PI. III. fig. 2) will show,

48 MR T. G. MOORHEAD.

in the lower part of the latter convolution. The area was, how-
ever, well developed even on the right side, and in drawing con-
clusions from the above figures the fallacy of measurements of
the superficial extent of small cortical areas, especially in the
neighbourhood of a sulcus so deep as that of Rolando, in which
I have found that on an average twenty-six square centimetres
of cortex lie below the level of the general surface of the brain,
must be borne in mind, and also the possible obscuring influence
of small secondary sulci, which, though they form lines of
demarcation, really inerease the extent of the main gyri. Thus,
cutting into the narrow part of the ascending parietal gyrus on
the right side, there is a small sulcus which narrows the gyrus,
but at the same time produces a bend in it which increases its
extent.

In order to determine if any appreciable difference in the
transverse width of the ‘motor’ convolutions existed in normal
brains, measurements of four other brains were taken, and it
was found that though there was no constant difference, yet
considerable variation existed, and that the differences observed
in the ascending frontal convolutions on the two sides of the
brain taken from the person who had congenital absence of the
arm were not at all above the average. The differences in the
ascending parietal convolutions in this brain were, however,
slightly greater than those ascertained to exist in the other four
brains, and were more strictly localised.

From uiy observations I therefore imagine that no naked-eye
atrophy of the arm-centre of Sherrington and Griinbaum exists
in the brain I have described, and that it demonstrates the
fact that congenital deficiency of a limb may exist without the
co-existence of atrophy of that portion of the cerebral cortex
which presides over its movements. The two brains described
in the papers already referred to also support this statement,
and indeed it is reasonable to expect that absence of a limb
should not affect more than the lower neurone territory. Unfor-
tunately the spinal cord in this case could not be obtained for
examination.

The diminution in size of the ascending parietal gyrus opposite
the arm-centre of the frontal gyrus, which was present to some
extent in the two previously reported cases, and also in the

Journ. of Anat. and Physiology, Oct. 1902.) [Puate III.

Fie. 1.

Fic, 2,

Mr T. G. Moornerap,

ey CEREBRAL CORTEX IN CONGENITAL ABSENCE OF LIMB. 49

resent instance, is a fact of extreme interest, more especially
ace it has been shown that this area does not possess motor

s. I have had the advantage of seeing Professor
ingham’s collection of fetal brains, in which it is seen

_ frontal gyrus, and that portion of the parietal gyrus which lies
_ immediately opposite to it, behind the fissure of Rolando,
a develop together, and form a marked elevation on the surface of
_ the brain on either side of the shallow part of the fissure of
- Rolando. From the way in which they develop together it
certainly suggests the conclusion that.these two parts are
_ functionally co-related; and though we have as yet no definite
information regarding the function of the parietal part, I
believe that Professor Cunningham inclines to the opinion that
- it acts as the receiving area for sensory impressions conveyed
from the upper limb. If this be the case, it is possible to under-
stand how such an area would be diminished in size in cases in
which the upper limb was deficient.

Owing to the manner in which the specimen was preserved
no microscopical examination of the cortex could be made, but
in Gowers’ case, and in that of Bastian and Horsley, no micro-
scopical change could be detected. Whether improved methods
of preparation and staining will show a distinction on the two
_ sides in such cases remains a question for the future.

REFERENCES.

_ (1) “The Brain in Congenital Absence of One Hand,” by W. R.
M.D., Brain, 1878.

(2) “ Arrest of Development in the Left Upper Limb, in Associa-
_ tion with an extremely small Right Ascending Parietal Convolution, fe
_ by H. Charlton Bastian, M.D., F.R.S., and Victor Horsley, Brain,
-Wol. iii., 1880-1881.
a (3) Abstract from experimental work on the motor regions of the
__ cerebral cortex, by Professors Sherrington and Griinbaum, Lancet,
Nov. 21, 1901.

EXPLANATION OF PLATE IIL

Fig. 1. Photograph of a cast of the arm of the individual referred to
in the text.
i Fig. 2. The two cerebral hemispheres of the same individual. ©
: VOL. XXXVIL. (N.S. VOL. XVII.)—OCT. 1902. 4

THE FORM OF THE HUMAN SPLEEN.
By R. K. SHEPHERD, B.Sc.

(From the Anatomical Department of the University College, Cardiff.) *

IN ascertaining the exact shape which a soft pliable organ like
the spleen possesses in the living body, one meets with very
serious difficulties, as when the abdominal cavity is opened
after death such structures lose their true shape, and one may
get an altogether false idea of their outline when examining
them in this manner. To surmount these difficulties, it has
been customary within the last twenty or thirty years to
harden these soft organs before examining them, and even
before opening the cavity in which they are placed. This
hardening has been done mainly by the injection of special
hardening fluids, such as bichromate of potash,—this is nearly
always used in combination with aleohol,—chloride of zine, and
within recent years, formalin.

Attention was first drawn to the enormous advantage to be
obtained by hardening organs im situ by Professor His, and the
models of the various viscera which he prepared were for many
years the only ones well known. The method he used in the
preparation of these was, the injection of from five to ten litres
of a 5 per cent. to a 1 per cent. solution af chromic acid, under
pressure.” The organs thus hardened were isolated, and models
of them were prepared in plaster of Paris. Since 1878, when
His made his first models, other hardening fluids have been
tried; the one that has proved most successful, and is now
generally advocated by all anatomists, including Professor His,*
is a solution of formalin and alcohol. The viscera are hardened
much more rapidly when it is employed; and further, they are
not so cedematous as they are liable to be when other fluids are

‘ The work of this paper was undertaken as part of the scheme of study for
honours in Anatomy at the B.Sc. examination in the University of Wales.

* His, ‘‘ Uber Priparate zum Situs Viscerum u.s.w,” Archiv Sir Anat. u.
Physiol., Anat. Abth., 1878, p. 54.

* Verhandlungen der Anatomischen Gesellschaft, May 1899, p. 39.

;
7

THE FORM OF THE HUMAN SPLEEN. 51

spleen and other abdominal viscera by means of the reconstruc-

tion method. In this method the body is frozen and cut in
_ sections. The blocks or sections into which the body is cut are
hardened by immersion in spirit, or spirit and formalin, and the

separate pieces of any organ are removed, cast in plaster of
Paris, or modelled in soft wood. The separate parts when
joined together give a faithful representation of the organ.
Cunningham’s model of the spleen as prepared in this way
differs in some important respects from His’s.

The specimens from which the conclusions given in this
paper have been drawn were hardened in situ before the
abdominal cavity was opened. The bodies were hardened by
intravascular injection of formalin, but in one case potassium
bichromate was used instead.

General Form of the Spleen.

I have had an opportunity of examining about a dozen such
spleens, and although such a number is too few for one to be
able to dogmatise on any particular point, a good idea as to the
more general features which the spleen presents can be easily
obtained. When these spleens are placed side by side they are
seen to show enormous variations in size and shape. Neverthe-
less in every case they are alike in possessing one, and only one,
convex surface, which, when the spleen is in its place in the
abdomen, rests against the diaphragm. This surface is relatively
very large, and its convexity is most marked at the junction of
its upper and middle thirds, for the upper part of this surface
looks for the most part upwards, while the lower two-thirds

looks backwards and outwards, and so at the junction of the

two there is a marked convexity. As it is directed against the

abdominal wall here formed by the diaphragm, this surface

might well be called the parietal surface of the spleen. The
rest of the surface of the spleen looks into the abdominal
cavity and rests against other abdominal viscera; in contra-
distinction to the parietal surface, it may ‘be termed the visceral

1 Form of the Spleen and Kidneys,” Jowr. of Anat. and Phys., July 1895,
p. 501.

52 MR R. K. SHEPHERD.

surface. Unlike the parietal surface, the visceral surface is by
no means even approximately uniformly curved, but it presents
a number of areas or districts, which vary in the manner and
amount of the curvature of their surfaces. These areas are
usually three in number, and correspond to the so-called
‘renal, ‘gastric’ and ‘basal’ surfaces of Cunningham. In
every case one of these areas—the gastric—which is applied
against the fundus of the stomach, can always be easily
recognised, as it, and it alone, is always distinctly concave. In
connection with the constant concavity shown by this surface
it is interesting to note that Birmingham,” in his paper on
the shape of the stomach, states that however empty the
stomach may be, the fundus of the stomach does not collapse,
but always retains a considerable amount of rotundity, its
cavity being occupied by prominent folds of the thick mucous
membrane. The presence of the hilus upon this surface assists
in its identification. Another point which helps in the identi-
fication of this area is, that the border separating it from the
parietal surface is sharp, and frequently crenated or notched.
The renal area is in nearly every case flat, or more rarely
slightly concave from side to side. It is separated from the
parietal surface and from the gastric area by thick rounded
borders. The last of the three areas which compose the visceral
surface of the spleen, the so-called ‘colic’ or ‘basal’ surface of
Cunningham, is the most variable. The other areas vary but
slightly in extent and in the amount of concavity or convexity
which they present; this area, on the other hand, presents
marked differences in different specimens. When it is well
marked the area in question is usually in relation to the splenic
flexure of the colon, and hence the term ‘colic area’ is applicable
to it. In some cases this area is a relatively large triangular
district occupying the lower end of the visceral aspect of the
spleen, and having its apex directed upwards between the renal
and gastric areas. Its extent may approach that of the renal
area. In other cases the area in question becomes very narrow,
or is so reduced that the gastric and renal areas are practically

1 Loe. cit., pp. 505-506.

2**Points in the Anatomy of the Digestive System,” Jour. of Anat. -and
Phys., October 1900.

-

THE FORM OF THE HUMAN SPLEEN. 53

et from one end of the spleen to the other; in these
¢ the colic area is absent or reduced to a mere line or
order, separating the gastric and renal areas in the lower part
Or extent. (See fig. 1.)
ay A glance at the specimens, or at the outlines, which illus-
trate this paper will make it understood that upon the size
a shape of this colic area will depend to a very large extent
shape which a spleen will present. If this area is large and

FA

Fic. 1.—Feetal spleen, showing well marked tubercle bounded below by a fissure,

This specimen shows the visceral surface divided into only two areas, viz.,
gastric and renal. These two areas are separated by the intermediate
border, which is well defined above, but becomes flattened out as traced
downwards below the tubercle.

The anterior border is well marked and has three notches in it; the
posterior border has one notch only.

The hilus on the gastric area extends downwards below the level of the
tubercle ; the renal surface is flat. The lower end of the organ is smaller
than the upper end, and is distinctly pointed.

the spleen is, as described by him, an irregular tetrahedron. In
such cases the shape of the spleen might well be compared to
that of a spore from a spherical capsule with a large convex
surface looking outwards, and three triangular areas directed
inwards towards the central part of the capsule. In the case of

_ ¥

*
te
bi
rE
oP

54 MR R. K. SHEPHERD,

such a spore these triangular areas would be in contact with the
corresponding areas of other spores. These three areas would
represent the gastric, renal and colic areas of the spleen, while
the large external convex area would correspond to the parietal
surface of the spleen. It must here be noted that Cunningham
applies the term ‘ base’ or ‘ basal’ surface to the colic area, and
‘apex’ to the upper angle of the spleen. The apex of the
tetrahedron as here described will correspond to Cunningham’s
‘internal basal angle, and is the point where the three visceral
areas meet, while the base is the parietal surface. Now, turning
to the other form which the spleen sometimes exhibits, we note
that as the colic area becomes reduced, the spleen assumes the
outline of a three-sided figure, which might well be compared to
a segment, or fig, of an orange. Its surfaces, now three in
number, are—the parietal surface, and the gastric and renal
areas. The flat surfaces of the orange segment are represented
by the renal and gastric areas, while the outer convex surface of
the segment corresponds to the parietal surface in the case of
the spleen. As the upper end of the spleen in these cases is
found to be more massive than the lower end, the outline of the
organ resembles a segment of a somewhat pear-shaped body, |
rather than a segment of a spherical body like an orange. It
will readily be understood that in this latter type of spleen the
parietal surface is somewhat oval, and each of the visceral areas
somewhat crescentic in outline; while in the tetrahedral form,
each of these areas is triangular in outline. When the outlines
of a number of spleens are examined it will be found that they
show nearly every stage in the transformation of the irregular
tetrahedron into a figure resembling a segment of an orange.
Of course, with a larger number of spleens, the series could
probably be made more complete, but as it stands it clearly
brings out the fact that what might be called the ‘tetrahedral
type’ of spleen becomes transformed into the ‘segment type’
by the gradual decrease in size of the colic area, accompanied by
a simultaneous decrease in size of the lower end of the organ.
(See figs. 1, 2 and 3.)

These differences in form presented by the spleen appear to
depend to a very large extent upon the condition of distension
or contraction of the neighbouring structures. It is only to be

THE FORM OF THE HUMAN SPLEEN. . 55

eted that the amount of surface in relation to the stomach
e » colon should depend largely on the relative sizes or
t of distension of these parts of the alimentary canal. It
e regretted that the condition of the stomach and colon,
efor amaovel of the spleen, was not noted in many cases; not-
" él hstanding this, however, it is practically certain that the

riations in the shape of the spleen were intimately associated
me of the cases, at all events, with definite conditions of

+ Pe 2.—An adult spleen, showing renal and gastric areas, and a small colic area ;
____ this spleen is well notched, and the notches are in every case save one con-
tinued into fissures in the parietal, renal and gastric surfaces. The anterior
angle is not prominent, the most anterior point being situated higher up on
the anterior border, —

. fe neighbouring viscera. It would now appear to be a well
established fact that when the stomach is empty the colon rises
up to take its place and fill the gastro-colic chamber; as the
___ colon rises up to oceupy a position formerly filled by the stomach,
it necessarily comes more fully into relation with the spleen.
The gastric area is therefore reduced to the advantage of the

56 MR R. K. SHEPHERD.

growing colic area. On the other hand, as the stomach becomes
distended the reverse occurs, the colon sinks, and the colic area
of contact becomes reduced, so that finally merely the lower
part of the border separating the gastric and renal areas is in
relation to the colon. The increase in width and thickness of
the lower end of the spleen, which is especially seen in spleens
where the colic area is large, is also to be associated with the
upward thrust of the colon, in conjunction with an empty or
almost empty stomach. It is worth while noting that the
models prepared by His and Cunningham. fully support this
view. In His’s model the stomach is distended and the colon not
much so; here we find a very minute colic area, and the spleen
is of the orange-segment type. In Cunningham’s model, on the
other hand, the stomach is empty and the colon very greatly
distended, and associated with these conditions there is a large
colic area and a tetrahedral type of spleen.

One would perhaps expect the extent, or the presence even,
of the colic area to depend to some degree upon the form and
size of the spleen itself, ¢.g., a short, small spleen might be less
likely to have a colic area than a long, big one; nevertheless,
among the specimens examined, there have been small spleens
showing well marked colic areas, and large ones showing no such
area at all. It will thus be seen that the differences to be
observed in His’s and Cunningham’s models do not indicate that
in either case an abnormal or atypical spleen has been present,
but rather that each observer has modelled a form of spleen
which normally occurs in man. Between the forms repre-
sented by the two models every possible intermediate stage
may be found, and the marked differences appear to be due to
the fact that the condition of the neighbouring viscera—stomach
and colon—was exactly opposite in the two cases. One im-
portant distinction does exist, and has been duly noted by
Cunningham ; it has to do with the relation of the renal surface
to the kidney,! and will be dealt with later on.

As the difference between the two forms of spleens is due toa
difference in the amount of distension of the stomach and colon,
intermediate stages are easily obtained in which variations in the
amount of colic area are seen, due to the variations in the disten-

1 See p. 63.

THE FORM OF THE HUMAN SPLEEN. 57

5 sion of the stomach and colon. From an examination of these
__ intermediate forms of spleens the following changes may be said
to oceur in the transformation of a three-sided orange-segment
‘type of spleen into the tetrahedral type of spleen :—First, the
lower portion of the border separating the gastric and renal
areas is blotted out—obliterated by the upward pressure of the
_ olon; and at the same time the lower end of the spleen is
_ pushed upwards against the portion above by the distending
___ olon, thus widening and thickening the lower end of the organ.
_ As the colon becomes more distended the lower end of the spleen
becomes pushed outwards and upwards, so that the visceral
surface of the lower end comes to look downwards as well as
inwards, and thus becomes separated off from the rest of the
visceral surface by definite borders. When the colon becomes
very distended this surface comes to look directly downwards,
and the lower end of the spleen is greatly thickened. This must
only be considered to be a general account of the changes that
oceur: a far larger number of bodies would have to be examined
before a really accurate account of the changes could be given.
The fact that it is the hollow organs which indent or groove the
- solid ones appears to have been recognised first by His when
conducting his early experiments upon hardening viscera in
situ. This observation has been abundantly confirmed by other
workers.

fe.

Borders of the Spleen.

Every spleen, whichever type it belongs to, presents three
borders separating the three constant surfaces or areas, viz,
the parietal, the gastric, and the renal. These three borders are
called anterior, posterior and intermediate, and correspond to
_ Luschka’s ‘margo crenatus, ‘margo obtusus, and ‘margo
__ intermedius.’ They separate the parietal surface from the
gastric and renal areas, and the gastric and renal areas from one
another. (See fig. 1.)

4 The intermediate border runs from the upper end of
_ the spleen downwards, separating the renal and gastric
} areas. The border ends either at the lower end of the
spleen when there is no colic area, or when this area is distinct

58 - MR R. K. SHEPHERD.

the border in question ends at Cunningham’s ‘internal basal
angle, ! where it bifurcates into the two borders which separate
the colic area from the renal and gastric areas respectively.
The border is rounded especially in its lower portion ; its upper
part, much more acute and distinct generally, overhangs to a
slight extent the upper part of the gastric area. The inter-
mediate border is not straight, but is usually slightly curved,
having the convexity of the curve looking backwards and
inwards; this being so, the border is gently continued at the
upper end of the spleen, or superior angle — Cunningham’s
‘apex ’—into the anterior border of the spleen. (See fig. 3.)
At some distance from its upper end the intermediate border
often presents a tubercle of varying size; this tubercle is
present in a large proportion of spleens, whatever their shape,
and varies from a slight, hardly noticeable elevation, to a promi-
nent tubercle, standing well out from the rest of the organ.
When well marked the tubercle is sharply defined below, while.

superiorly it is continued into the prominent upper part of the ~

intermediate border. In some of these cases the intermediate
border might almost be said to end in this border, as below it
the border is so flattened that it cannot be satisfactorily traced.
On the other hand, in those specimens which show no tubercle,
the intermediate border is not flattened out inferiorly, but can
be easily traced to the apex of the colic area. In connection
with this tubercle, it should be noted that there is generally to
be seen a fissure, either extending from the posterior border,
from a point usually situated in its upper half, towards the
tubercle, or encircling it below. (See fig. 1.)

Whether the tubercle has any developmental or embryo-
logical significance, it is not possible to say at present; it is
certainly very well marked in many foetal spleens. My ob-
servations seem to show that this tubercle fits in above the tail
of the pancreas, which rests against the flattened area below.
When the tubercle is absent, the intermediate border is not.
flattened inferiorly, and so I am inclined to believe that the
presence of the tubercle is to be associated with a close relation-
ship of the tail of the pancreas to the spleen. If this is correct,
one would expect the tubercle to be absent in cases in which

1 Loc. cit., p. 505.

—

THE FORM OF THE HUMAN SPLEEN. 59

the tail of the pancreas did not reach the spleen, or in which
| “ part of the gland was feebly developed, I have found the
tub 2 to be crossed either by the splenic artery itself, or by
e of its branches going to the upper end of the hilus. A
pete the vessel may sometimes be seen upon the. tubercle
| hardened specimens.
‘The terior, or erenated border, rans from the upper end of
heen downwards and forwards, separating the gastric area
a the parietal surface. This border ends below, either at the
_ lower end of the spleen by joining the posterior and inter-
; mediate borders when there is no colic area, or at the anterior
angle of the spleen when the area in question is present. This
border i is the most acute of the three primary borders, and is
_ continuous with the intermediate and posterior borders at the
upper end of the spleen. Its upper third is directed more or
a _ less outwards, its lower two-thirds downwards and forwards; as
_ a consequence of this, the most anterior point of this border is
TS acnorally somewhere about its lower end; this point is
i Se Renninghart s ‘anterior basal angle, and is usually very promi-
_ nent in a tetrahedral type of spleen, though this is not always
i _ the case.
_ Avery characteristic point with regard to the anterior border
__ is the notching it often shows all along its course; this appear-
Q _ ance gave rise to Luschka’s name for it—‘ margo crenatus.’ The
~ notching i is seen in nearly every spleen, the actual number of
notches being extremely variable; in some cases five, or even
; - more, have been found, but on the whole, the average number
Ect notches is about two. The notches, which vary in depth
from a quarter of an inch to an inch, or even more, may or may
not be continued into fissures on the parietal surface; about
half of them are usually so continued. The fissures usually run
downwards, backwards and inwards, and in some cases they
_ stretch right across the parietal surface so as to cut into and
notch the posterior border of the spleen.
__ The posterior border is placed between the renal area and the
parietal surface. It runs from the upper extremity of the
organ, first of all outwards and backwards, and then downwards,
either to the lower extremity in the orange-segment type of
spleen, or to the posterior angle in the tetrahedral type of

eis ie =

60 MR R. K. SHEPHERD.

spleen. At this angle the posterior border meets the border
separating the colic and renal areas; Cunningham calls this
point the ‘posterior basal angle.’ The posterior border is thick
in the whole of its extent; in its upper part, this border seems
to fade away so that there is no definite line of separation
between the renal area and parietal surface. The border is
sometimes notched like the anterior one, only not to such a
great extent; in nearly all cases, however, the notches, when

Intermediate
Superior angle border

Posterior
border

Anterior border

Renal afea

Gastrie area

Anterior limb of
intermediate
border

Intermediate

angle
Anterior angle
Posterior
angle
Colic area
Posterior limb of Inferior border
intermediate border

Fic. 3.—A child’s spleen. This is a fairly typical tetrahedral spleen ; it has no
tubercle, and only shows notching on the anterior border. The anterior angle
is prominent.

present, are continued into fissures on the parietal surface, as
Parsons’ has recently pointed out, and in some they are also
continued into fissures on the renal area, such fissures being
directed towards the tubercle on the intermediate border. The
fissures on the parietal surface are directed upwards, forwards
and slightly outwards. As a rule, not more than one fissure

1 “ Notches and Fissures of the Spleen,” Jour. of Anat. and Phys., vol. xxxv.
p. 422.

THE FORM OF THE HUMAN SPLEEN. 61

is to be seen on the parietal surface, but two are by no means
infrequent.

These three—the anterior, posterior and intermediate—may
be called the three primary borders, since they are always
present; there are, however, three secondary borders which are
to be seen in spleens of the tetrahedral type, or those showing
a colic area. These latter borders serve to delimit the colic area,
and separate it from the renal and gastric areas and from the
parietal surface. (See fig. 3.)

The inferior border is the best marked of these secondary
borders ; it stretches from the anterior angle of the spleen to
the posterior angle, and is placed between the colic area and
the parietal surface. This border may be notched like the
anterior and posterior borders, but the notching, which is in-
significant, is of very rare occurrence. The other two borders
are by no means distinct save in specimens showing a well
marked colic area, and in these the border separating the colic
and gastric areas is the better marked of the two. These two
borders and the intermediate border meet internally at a point
—the intermediate angle—Cunningham’s ‘internal basal angle ’
—which is usually very indistinct except in typically tetra-
hedral spleens. This angle forms the apex of the flattened
tetrahedron, whose base is the parietal surface. It has already
been mentioned that the points where the two borders sepa-
rating the colic from the renal and gastric areas meet the
posterior and anterior borders respectively are called the
posterior and anterior angles of the spleen. It should be noted
here that the anterior angle is not always the most anterior
point of the spleen; in some cases the most anterior point is
situated higher up on the anterior border, and in these cases
the anterior angle is by no means distinct.

The spleen has two extremities—an upper and a lower;
the upper end or superior angle of the spleen is posterior and
internal to the lower, as well as being superior to it. The upper
end of the spleen is rounded, the superior angle being incurved.

The lower end varies from being sharp and pointed in a
‘segment type’ of spleen to wide and thick ; in fact, it becomes
a whole surface when the spleen is tetrahedral in outline. The
notching of the spleen has attracted some attention recently.

62 : MR k. K. SHEPHERD.

In England, Parsons! has recorded a number of observations,
made chiefly in the post-mortem room, on normal spleens. The
statements made in this paper are, as far as they go, in agree-
ment with his results, but he has also noted cases in which
fissures were present on the parietal surface only, not extending
to the borders bounding the surface. He concludes that the
notching is, in a general way, dependent on the arrangement
of the large blood-vessels. He finds that in some animals, such
as the seal, the notches seem to correspond to the blood-vessels
entering the hilus; but Parsons admits that in man, at all
events, the notches do not show a dependence upon the dis-
tribution of the vessels in all cases. Another theory regards
the notches as having developmental significance, but unfortu-
nately there is no trace of a primitive lobulation in the human
foetal spleen, unless except possibly the tubercle of the inter-
mediate border is to be looked upon as an indication of primi-
tive lobulation. Further, Parsons states that the notches are
relatively less marked in the foetus than in the adult, and also
the number of the fissures seems to increase as adult life is
approached. Lobulation, too, is not seen in lower vertebrates
till we get back to the elasmobranchs, and even then it is not
found in every species; so at present, at all events, this theory
must be discarded.”

It has been further suggested that the notches are due to
processes of peritoneum passing to the notches from the peritoneal
ligaments, and thus acting as a check on growth at such points.
Such peritoneal processes are occasionally met with in man, but
are comparatively rare, and so could not by any means account
for the large number of notches that are frequently met with.
Up to the present, therefore, no satisfactory theory as to the
origin ‘of the notches has been propounded, none of those
mentioned above being satisfactory.

Surfaces of the Spleen.

A general description of the surfaces of the spleen has already
been given; a few minor points of detail have yet to be
mentioned.

1 Loe. cit., p. 416. 2 Loe. cit., p. 426.

——

THE FORM OF THE HUMAN SPLEEN. 63

The parietal surface is in relation to the diaphragm, being
separated by the diaphragm and the thin basal margin of the
left lung from the ninth, tenth, and eleventh ribs; the longest
_ diameter of the spleen corresponds with the axis of the tenth
_ rib; it may have a vertical fissure in the middle of the surface,
as already mentioned; such fissures are, however, of rare
occurrence.

The gastric area is in relation to the fundus of the stomach;
it is not uniformly concave, the concavity increasing as we pass
towards the upper end of the spleen; the concavity is greatest
immediately to the outer side of the tubercle of the intermediate
border. In this area is placed the hilus of the spleen. This lies
about half an inch to the outer side of the intermediate border,
and extends from the level of the tubercle right down to the
lower end of the border. The hilus may be broken up into
three or four separate portions, or it may be one continuous
cleft-like depression. The splenic branches of the splenic artery
enter the spleen in three or four main groups; the highest-up
group enters in the deep concavity to the outer side of the
tubercle. A secondary hilus is sometimes seen at the upper end
of the spleen; it extends from the superior extremity of the
spleen to the level of the tubercle along the line of attachment
of the lieno-phrenic ligament, and lies above and behind the
primary hilus of the spleen; the arteries that enter the
spleen in this part are derived either from the splenic artery
or from the left inferior phrenic artery; the surface of the
organ is not depressed to form a cleft or fissure where they
enter.

The renal area is in relation to the left kidney. His made this
surface deeply concave both in its long diameter and from side
to side, and his models show this surface applied against the
outer border of the kidney. Cunningham, on the other hand,
makes his renal surface flat and even, and shows it to be
applied against the anterior surface of the kidney, In all the
spleens examined ‘in connection with this paper the renal area
has been found flat, or a trifle concave in one or two instances.
In all the cases it was in relation to the upper part of the
anterior surface of the left kidney in its outer part; in one or
two cases it was also related to the left suprarenal capsule.

64 MR R. K. SHEPHERD.

In the foetal abdomen this surface is related to the left supra-
renal capsule rather than to the kidney.

The colic area is in relation to the summit of the splenic
flexure of the colon ; when present it is triangular in outline, and
is usually flattened; in one or two cases where the spleen is
markedly tetrahedral, this area is slightly concave; except in
such cases the colic area is not well marked off from the
gastric and renal areas, the lines of demarcation being indefinite.
As might be expected from the fact that the colic area of
tetrahedral spleens is simply a cut-off part of the gastric area of
the segment type of spleens, one or two branches of the splenic
artery are occasionally found to enter the spleen in this area.
In some of the cases examined the spleen has not been in direct
contact with the other viscera, but was separated from them by
a mass of fat. This is well seen in a frozen section in the
collection at Cardiff. .It is important to note that even in
these cases the impressions were always well marked,

Attachment of Peritonewm to the Spleen.

Peritoneal ligaments, or omenta, pass to the spleen from three
other structures in the abdomen. First, there is the gastro-
splenie omentum passing from the fundus of the stomach to the
hilus of the spleen; processes of peritoneum. pass from this
omentum in rare cases to the anterior notches. In all cases
where the anterior angle is well developed a process of peritoneum
passes to the angle, and in some cases the angle is curved in-
wards. Whether this is due to the pull on the angle by the
omentum or not is doubtful. Second, there is the lieno-renal
ligament passing from the anterior surface of the kidney to the
hilus of the spleen. Third, there is the lieno-phrenic ligament
passing from the under surface of the diaphragm to the upper
end of the spleen, being attached along the upper portion of the
intermediate border, behind and above the gastro-splenic
omentum, with which it is continuous, and also with the gastro-
phrenic ligament. This ligament is not always present.

The following averages were obtained from an examination of
eight adult spleens, the measurements are in inches. The spleens
were weighed after hardening.

THE FORM OF THE HUMAN SPLEEN. 65

Average length of spleen,
Greatest length,
Least length, . :

Average breadth of spleen,
Greatest breadth,
Least breadth,

Average thickness of spleen,
‘Greatest thickness, .
Least thickness, .

Average weight of spleen,

Greatest weight,

Least weight, .

>
>

NS

HR CO Or bo DS OS WR OL
bate aoatoheo

oo
No
N

‘The. three outlines accompanying this paper are selected from
a series which have been drawn from the spleens after removal
from the body, by a camera lucida. The table gives the chief

; particulars of all the cases. In each case the weight and

_ extreme length is given. Fcetal spleens are marked with a star.

_ Since the above paper was written I have had the opportunity
of observing seven models prepared by Steger at Leipzig, under

___ the direction of Professor His, illustrating the anatomy of some
of the abdominal viscera.

3
3
=

I. 16 jahr Méidchen. Schniirmagen. Stomach is distended, spleen
“ona is of the orange-segment type.
IL. 16 jahr Mann. Kellner. Stomach is distended, spleen is of the
f orange-segment type.
UL. 40 jahr Frau im 5 Monat schicanger. Stomach is moderately
distended, the colic surface is seen.
IV. 40 jahr Frau. Schmiirmagen. Stomach is moderately distended,
' colic surface seen ; markings of ribs seen on parietal surface,
V. 20 jahr Mann. Normal. Stomach is contracted, only in contact
with a very limited area on the spleen; there is a large
4 colic area not sharply delimited.
' ‘VIL 56 jihr Mann. Trinker. A tetrahedral spleen ; the gastric area
: is only slightly in ‘contact with the stomach, the rest being
related to the large or small intestine.
_ VIL 25 jahr Frau im 2 Monat schwanger. Stomach is moderately
distended ; there is a small colic area.

All these bear out the statements in this paper except No.
VL., which is abnormal.

[ TABLE.
VOL. XXXVII. (N.S. VOL. XVII. )—OCT. 1902. 5

SHEPHERD.

K.

MR R.

66

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‘suaajdy UddRMOY, J 70) SUOVJDALISYC) pub SJUIMIAANS DI] buunoys ATAV L,

THE FORM OF THE HUMAN SPLEEN. 67

SUMMARY.

_ Asa result of the observations recorded, the following con-
clusions seem justified :—

we te (1) The normal spleen may be said to exhibit two chief
_ surfaces—Parietal and Visceral—the latter being divided into
two or three areas. :

‘There are two chief types of spleen form to be met with in
hardened subjects. In the one type the spleen is shaped like the
segment of a pear, and possesses a parietal surface—the convex
outer surface of the segment and two visceral areas—the two
flat surfaces of the segment. The inner of these areas is in
contact with the kidney and the outer with the stomach ; they
are called the renal and gastric areas. His’s model represents
this type of spleen, if one or two minor points of detail are
overlooked. In the other type, the spleen is shaped like an
irregular tetrahedron and has a parietal swrface—the base of
the tetrahedon ; and three visceral areas which meet internally
at a point—the intermediate angle—the apex of the tetrahedron.
These areas are the renal, gastric and colic areas, the last
named being in contact with the splenic fiexure of the
colon.

(2) The gastric and renal areas are separated by a border
which is always well marked—the intermediate border. The
gastric area is marked off from the parietal surface by the
anterior border, also well marked, while the renal area is
separated from the parietal surface by a border which is well
marked, especially in its lower portion—the posterior border,
These three borders are alone to be met with in the ‘segment’.
type of spleen; in the tetrahedral type there are three second-
ary borders as well as the three just mentioned. The inter-
mediate border ends below by bifurcating, so as to enclose the
colic surface; these two limbs into which it divides are not at
all well marked except in typical tetrahedral spleens. In these
the colic area is separated from the parietal surface by a
secondary border, which is fairly well marked—the. inferior
_ border.

(3) The lower end of the spleen varies a good deal in shape,

68 MR R. K. SHEPHERD.

being pointed in the ‘segment’ type, and wide and thick in
the tetrahedral type ; in fact, in this type it becomes a whole
surface—the colic surface.

(4) The two types of spleen appear to be due to differences
in the state of distension of the surrounding organs, chiefly
the stomach and colon. When the stomach is distended and
the colon is empty, the spleen is shaped like the segment of an
orange. When the conditions are reversed, the colon -being
distended and the stomach empty, the spleen is tetrahedral in
shape.

(5) A spleen belonging to one of these types becomes trans-
formed into the other type simply by a change in the condition
of the colon and stomach, and this transformation probably
takes place periodically in the living body.

(6) The renal area on the spleen. is flat, and is applied against
the upper part of the anterior surface of the left kidney in its
outer part, as described by Cunningham; in some cases it is
also related to the left suprarenal capsule. In the foetal abdo-
men this area is rather in relation to the left suprarenal capsule
than to the kidney.

(7) A tubercle is often found on the intermediate border ;
when present the portion of the border below it is usually very
much flattened, and is in relation to the tail of the pancreas.
When the tubercle is absent there is no flattening; the presence
of a marked tubercle appears to be associated with a close
relationship of the tail of the pancreas to the spleen.

(8) Notching of the borders and fissures of the surfaces were
noted; in nearly every case the anterior border was notched in
two or three places ; the posterior border was also notched, but
not nearly so frequently as in the case of the anterior border.
In nearly every one of the specimens examined which showed
posterior notches, the notches were continued into fissures on
the parietal surface.: The inferior border was found notched in
two instances only. No connection was noticed between the
arrangement of the notches and the mode of distribution of the
blood-vessels. The notches and fissures do not repeat ony early
lobulation of the organ.

(9) In nearly every case where the spleen is of the tetrahedral
type, a process of peritoneum is seen passing to the anterior

THE FORM OF THE HUMAN SPLEEN. 69

ee in these cases the angle is sania
t this is due to is doubtful.

PRELIMINARY NOTE ON THE POSITION OF THE
GALL-BLADDER IN THE HUMAN SUBJECT. By E.
Scorr CARMICHAEL, M.B., F.R.C.S.E., Senior Demonstrator
of Anatomy, New School, School of Medicine of the Royal
Colleges, Edinburgh.

THE ever increasing frequency with which abdominal viscera
are being subjected to surgical treatment renders a more exact
knowledge of their topographical anatomy of great practical
importance.

The difficulties of anatomists in definitely localising viscera
which are constantly varying in their shape, and, to a certain
extent, in their position within the abdominal cavity, are great ;
but much can yet be done by observing the more common
variations to ascertain their anatomical position more approxi-
mately.

During the last year I have had the opportunity of making
observations on a considerable number of abdomens in the
dissecting-rooms. These are, as a routine practice, hardened by
the injection of formalin into the stomach, bladder and rectum, -
a method carried out by Dr R. J. A. Berry on all subjects for
dissection.

These observations have been largely directed towards ascer-
taining the position of the gall-bladder, chiefly on account of
some pathological work which is at present being carried out
on that viscus.

The position of the gall-bladder in the abdomen is stated in
standard anatomical text-books to be situated opposite the ninth
right costal cartilage.

From a few observations on these formalin-hardened bodies,
one is struck with, firstly, the irregularity in length and position
of the 9th costal cartilage, making it not in any sense a re-
liable fixed point ; and secondly, the frequency with which the
gall-bladder has no close relationship to the cartilage.

To the surgeon particularly it is extremely difficult to define

THE GALL-BLADDER IN THE HUMAN SUBJECT. 71

the limits of the 9th costal cartilage, more especially as regards
its tip or termination.

In ten cases examined, the length of the cartilage varied from
5 to 12 cm., the average being 7°5 cm. or 3 inches—a consider-
able distance in which to localise the gall-bladder in a horizontal
direction.

The tip of the cartilage is found to vary very considerably in
the height to which it extends on the costal margin.

In taking the tip of the cartilage as a definite point, I found
that in only one out of the ten cases did the gall-bladder lie
behind it, while in four it lay from 2 to 4 cm. above it under
the costal margin, and the remaining five 2°5 to 8 cm. below
it, showing in these ten subjects a difference of nearly 5 inches
(12 em.) in its position in a vertical direction.

Its variations in a horizontal plane, as measured by taking
the right lateral line of Addison as the fixed point, showed that
in seven cases tested, the gall-bladder lay from 1 to 6 em. ex-
ternal to that line, while in another case it lay as much as 9 cm.
outside the right lateral line, and parallel to the 11th costal
cartilage.

Of the seven cases referred to, the lateral position of the gall-
bladder varied in five cases from 2 to 4 cm. outside Addison’s
right lateral line.

Observations on a larger number of bodies in the dissecting
and post-mortem rooms, with or without formalin injection, will
doubtless lead to a more definite localisation of this viscus, not
to a fixed point, but to a fixed line, such as the right lateral
line of Addison, whose method of abdominal localisation lends
itself as a more reliable means of fixing the position of an
abdominal viscus.

The variation in position of the gall-bladder is much greater
in the vertical than in the horizontal direction, and would
suggest some vertical line along which this variation extends as
the better means of localising its position.

Addison’s lateral line in all cases examined touches the
clavicle considerably internal to its mid-point, and apparently
at a fairly constant distance. This distance in five cases ob-
served was from 3 to 4°5 cm.

The gall-bladder, lying as it does in about 90 per cent. of

72 THE GALL-BLADDER IN THE HUMAN SUBJECT.

cases external to Addison’s right lateral line, corresponds very
much in its position to that line to the mid-clavicular point.
The following table of five cases will illustrate my meaning :—

1. Gall-bladder lay 2°5 cm. outside Addison’s Mid.-clav. pointlay 4 cm. outside Addison’s
Line. Line.

2 ” 3°5 cm. ” ” ” ” 4°5 cm. ” ”

3. ” ” 3 cm. ” ” ” ” 3 cm. 9 ”

4 2: ‘cm. “3 + 4. + #5 Cin, Se oy

5 ” ” 2 cm. ” ” ” 9 3°5 cm. 29 ”

The measurements were made from the lateral line to the
nearest point on the fundus. The breadth of the fundus of the
gall-bladder in these cases was from 2 to 3 em., so that a vertical
line dropped from the mid-clavicular point crossed in all these
cases some part of the fundus of the gall-bladder.

It is my intention, by further observation, to investigate the
relationship of the gall-bladder to the lateral line of Addison,
or to the mid-clavicular line, both of which are more fixed and
more easily obtainable to the practical surgeon than any point
on, or even the whole of, the 9th costal cartilage.

My conclusions on these few observations are :—

Firstly. That the statements in text-books localising the gall-
bladder as lying opposite the 9th costal cartilage are in up-
wards of 75 per cent. of cases erroneous.

Secondly. That the 9th costal cartilage itself is a very un-
reliable fixed point, on account of its variability in length and
extent.

Thirdly. That any localisation of the gall-bladder must be
rather by a vertical than a horizontal line.

Fourthly. That the gall-bladder lies in 90 per cent. of cases
outside Addison’s right lateral line.

Fifthly. That the gall-bladder is crossed at its fundus in most
cases by a vertical line drawn from the mid-point of the clavicle.

? ON kn i

a
4
4
z
4

‘|

THE DEVELOPMENT OF THE HEAD MUSCLES IN
SCYLLIUM CANICULA. By F. H. Epceworrn, M.B.,
BSe., Assistant Physician to the Bristol Royal Infirmary.
(PLates IV.—X.)

(From Prof. Faweett’s Laboratory, University College, Bristol.)

TuHE theories of Balfour and v. Wijhe on the morphological
position of the muscles developed from the walls of the head-
cavities lying between the gill-clefts in the Elasmobranch head
are so divergent—the former holding that they are somatic, the
latter that they are splanchnic structures—that the subject
appeared worthy of’ reinvestigation, especially in view of the
fact that what is true of the Elasmobranchs probably holds for
Vertebrates in general.

The following is a summary of their statements. The head-cavity of
Elasmobranchs was discovered by Balfour,! who describes it as a slit
developed in the mesoblast sheet lying on either side of the forepart
of the alimentary canal.

The successive formation of the gill-clefts, from before backwards,
divides this head-cavity into portions lying in the respective gill-
arches. The head-cavity lying in front of the hyomandibular cleft
divides spontaneously into two parts, a posterior in the mandibular
arch, and an anterior, or premandibular, situated close to the eye.
The premandibular cavity is prolonged ventrally and meets its fellow
below the brain. Balfour was of opinion that the eye-muscles would
be found to be developed from the walls of this cavity. The man-
dibular cavity becomes spatulate in shape, forming a flattened cavity,
dilated dorsally, and produced ventrally into a long thin process
parallel to the hyomandibular gill-cleft. The upper dilated part
atrophies, whilst the splanchnic wall of the lower part thickens.
There is a similar section of the head-cavity in each of the remaining
arches, though a dorsal dilated portion (which soon atrophies) is
present in the hyoid section only. Whilst the cavities of the head-
¢avities in the gill-arches collapse, their walls thicken, and become
converted into muscles—‘‘ their exact history I have not followed out,
but they unquestionably become the m. constrictor superficialis and
m. interbranchialis, and probably also the m. levator mandibule and
other muscles of the front part of the head.” The fact that the walls of
the sections of the body-cavity in the head become converted into
muscles “renders it almost certain that we must regard them as
equivalent to the muscle-plates of the body which originally contain,
equally with those of the head, sections of the body-cavity.”

1 This Journal, vol. x., 1880.

74 MR F. H. EDGEWORTH.

Balfour also described, behind the auditory involution, a few
longitudinal muscles, which he was inclined to think were a part of
the trunk system of muscles overlapping the back part of the head.

A little later, Marshall! confirmed in part the suggestion of Balfour,
by showing that the walls of the premandibular cavity develop into
the rectus superior, internus and inferior, and probably the inferior
oblique, eye-muscles. He also gave good reasons for thinking that the
external rectus is developed from the dorsal dilated portion of the
hyoid cavity. He did not trace the origin of the superior oblique.

In the following year v. Wijhe? published his important paper on
the development of the muscles and nerves of the Elasmobranch head.
The following is his tabular statement of the development of the
muscles : —

Aus dem Myotome

Ventrale Visceral- Dorsale
ppg Nervenwurzel bogenhohle Nervenwurzel
Segmente ES
6 Bu ae
cS aoe
aie
Bee
pa 8 9
se &
E28:
so Z&
— od
+
<
1 Rect. sup. int. inf,
oblig.. inf: ...:;.° apes. a g . . oph. prof, .
2. Oblig. sup. +. 5 5 ee ages . . v. (Nach Abzag
as des oph. prof.)
So. Rectpext) woh ahaa vi oa P ae
4 Sek. aba eee g5 . Aucusticofacialis
5 0 x iteiea: ee ee a glossopharyngeus
6 Sehr rudimentir . nicht a
wahrgenommen Aip =
7\ Von Schadel zum ae
8] Schultergurtel * a vale
9| ziehende Muskeln | 6
nebst dem _ vor- o 5
dersten Theile der a2
Sternohyoideus SF

The 4th and 5th myotomes altogether atrophy, whilst the 6th of the
latest stage seen was very rudimentary, and so probably atrophies.
The development of the ventral longitudinal muscles is as follows—
‘Das rudimentiire sechste” (i.e. myotome) “liegt noch stets an der
Innenseite des R. branchialis I Vagi, aber die folgenden haben sich
dorsalwiirts verliingert, ebenso wie die Myotome des Rumpfes.
Ausserdem kommt eine ventrale Verliingerung dem hintersten Kopf-

? Quart. Jour. Mier, Sci., vol. xxi., 1881.
* ““ Ueber die Mesodermsegmente und die Entwickelung der Nerven des
Selachierkopfes,” Verhand. der K. Acad. der Wissen. zu Amsterdam, 1882.

_ aetna

DEVELOPMENT OF HEAD MUSCLES IN SCYLLIUM CANICULA. 75

zu, fehlt dem vordersten (dem Isten bis 6ten) aber vollstin-

dig. (Note.—Ob das siebente und achte Myotom sich in spiiten Stadien
auch noch weit ventralwirts ausstrecken habe ich nicht ermittelt.)
Schon gegen das Ende des Stadium K. fiingt die ventrale Verlinge-

tung, sowohl des hinstersten Kopfmyotome als die der vorderen
Rumpfmyotome sich nach vorn umzubiegen an. Im Stadium O
haben diese Verliingerungen, welche spiiter selbststandig werden, schon

iemlich weit nach vorn vorgegriffen. Aus ihnen entwickelt sich der

Muse. coraco-hyoideus, welche also genetisch von der ubrigen, aus den
Seitenplatten stammenden Kiemen- u. Kiefermusculatur, ganz

. verschiedenist. Der Muse. coraco-branchialis + coraco-mandibularis

hat eine ganz andere Entstehungsweise als der coraco-hyoideus. Es
entwickelt sich nimlich aus der unpaaren vorderen Verlingerung des
Pericardiums, dessen Hthle, wie wir gesehen haben im Stadium J mit
den Hohlen der Visceralbogen communicirt. Nach dem Stadium K
fiingt diese vordere Verliingerung zu obliteriren an; die Zellen ihrer
Winde werden Muskelfasern und im Anfang des O ist der ganze
Hohle geschwunden ; ihre muskelésen Wiinde sind zusammengekom-
men, und bilden die Anlage des Muse. coraco-mandibularis + coraco-
branchialis. In spiter Stadien ist derselbe immer leicht von dem
Muse. coraco-hyoideus zu unterscheiden. Die Nebenzweige, welche
ersterer zu den Visceralbogen abgiebt, sind aus den Unterenden der
Wiande der Visceralbogenhdhlen entstanden.”

Balfour’s view that the cavities in the gill-arches are homologous
with those of the somites of the trunk is untenable. ‘Es scheint mir
sicher das hauptsiichlich die Verthiltnisse im Stadium J beweisen dass
sie” (i.e. the cavities in the gill-arches) ‘“dagegen mit einem
Absehnitt der bleibenden Leibeshdhle des Rumpfes zu homologisiren
sind ; ich stelle die Griinde zusammen. In der ersten Hilfte des
Stadium J hat sich die primire Leibeshdhle in die Héhlen der Myotome
und die secundiire Leibeshéhle differenzirt, durch die Trennung der
Somite (mit Ausnahme des 2ten) von die Seitenplatten ; die Hohlen
in den Visceralbogen erstrecken sich nun nicht iiber die untere
Grenze der Somitenplatte (resp. Myotomenplatte) und sind von den
Héhlen der Somiten (mit Ausnahme derjenigen des zweiten) getrenrt ;
sie communiciren aber mit den Pericardiumraume. Ausserdemwerden,
Wie wir in Stadium I gesehen haben, die Kiementaschen unter der
Somitenplatte angelegt. Wiiren dagegen die Hihlen in den Visceral-
bogen mit denen der Somiten vergleichbar, so miissten sie alle
ursprunglich mit einer der letzteren (oder der Myotome) in Ver-
bindung stehen, und dies ist fiir diejenigen der hinteren Visceralbogen

‘nicht der Fall.”

Before describing the results of my own observations, one or
two remarks may be made concerning these various statements.
The IXth nerve—that of the 1st branchial segment—is that
of v. Wijhe’s 5th head segment. There are thus four segments
anterior to it; whilst according to Balfour there are only three

76 MR F, H. EDGEWORTH.

—the premandibular, mandibular and hyoid. Marshall showed
that from the premandibular segment the superior, internal and
inferior rectus, and the inferior oblique muscles develop, and
from the upper end of the hyoid the external rectus. These
are clearly the 1st and 3rd myotomes of v. Wijhe, whilst from
his 2nd myotome the superior oblique is formed. It follows
that, according to v. Wijhe, there are two myotomes (his 3rd
and 4th) in the hyoid segment ; of which the anterior develops
into the external rectus, and the posterior atrophies.

In v. Wijhe’s tabular statement it is said that the 7th, 8th
and 9th myotomes give rise to the “ Vom Schadel zum Schulter-
gurtel ziehende Muskeln nebst dem vordersten Theile des
Sternohyoideus.” In the text of the paper (quoted above) he
states that the sterno-hyoideus develops from the ventral ends
of the 9th head- and the most anterior trunk-myotomes, and
that it had not been determined whether the 7th and 8th
myotomes also grow downwards. It is also to be noted that he
does not describe or picture the development of any muscles
passing from the skull to the shoulder-girdle. According to
Vetter,’ there is only one such muscle—the trapezius.

The result of my observations is as follows: The embryos
were bought from the Laboratory of the. British Marine
Association at Plymouth. They had been fixed in corrosive
sublimate and acetic acid. They were stained in Mayer’s acid
carmine solution, imbedded in paraffin, and cut into serial
sections in transverse and vertical longitudinal planes. The
development was followed from Balfour’s stage H onwards.

In stage I the pericardium consists of two portions, which
are continuous with each other, an anterior or cephalic in the
five branchial segments, and a posterior or cervical portion in
the neck. The former contains the ventral aorta, the latter the
heart (fig. 34).

The cephalic portion of the pericardium is developed as
follows: The formation of the gill-slits does not interrupt the
continuity of the head-cavity from segment to segment ventro-
lateral to the gut on each side of the head, though it does do so
laterally. The pericardium is formed in the 1st and sueceed-

1 “Kiemen-und Kiefer-muskulatur der Fische,” Jenaische Zeitschrift, vol.
viii., 1874.

TELOPMENT OF HEAD MUSCLES IN SCYLLIUM CANICULA. 77

a

ing branchial segments, by approximation of the lower ends of

e head-cavity and breaking down of the two splanchnic
srs, 80 that it becomes continuous from side to side across
ie median line ventral to the gut. The ventral aorta is formed

_ just above, and indents, the dorsal wall of the pericardium. A
Ne “Dy action of the head-cavity extends upwards, on each side, from
: = lateral edge of the pericardium between each two gill-
c , the last being just behind the 4th branchial gill-slit.

The: lower end of the cavity in the mandibular segment is
_ continuous with that in the lower end of the hyoid segment,
and that again with the pericardium which begins in the Ist
branchial segment, but in neither the mandibular nor the hyoid
‘segment does this cavity become continuous with its fellow
across the median line ventral to the gut. These communica-
tions between the lower ends of the mandibular, hyoid, and 1st
_ branchial, head-cavities become obliterated by stage K (fig. 7),
though the hyoid and mandibular cavities themselves do not
3 j _ disappear until much later.
In the hinder branchial segments the pericardium enlarges
___ by a bulging upward of its upper wall, so that the lower ends of
the sections of the head-cavity between the gill-slits no longer
- join the upper lateral edge, but the outer wall, of the peri-
a eardium (figs. 12, 13, 14). This enlargement is owing to the
_ development and forward bulging of the heart, the auricle of
ae Gwliich. is now seen in transverse sections of the 4th and 5th
branchial segments; whereas previously the heart was confined
to the cervical region, and there was only the ventral aorta in
the cephalic part of the pericardium (fig 3).
_ The cephalic portion of the pericardium is thus in early.
Stages present in all the branchial segments; later on its
anterior extremity retreats, so that in stage M it does not exist in
the 1st but only in the 2nd and succeeding branchial segments
(figs. 20, 21, 22); and finally it appears somewhat suddenly in the
4th branchial segment and is absent in the first three. This
disappearance of the anterior part of the cephalic portion of the
_ Pericardium is not due to a collapse of its walls, but to a gradual
“retreat of its anterior end, owing doubtless to a deficiency in
growth relative to that of the rest of the head.

The fate of the sections of the body-cavity extending up-

a
-
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—

78 MR F. H. EDGEWORTH.

wards from the pericardium between the gill-slits may now be
considered, and they may be taken together, as their develop-
ment is almost identical in all the five branchial arches.

The upper ends of these branchial head-cavities are a little
dorsal to the upper ends of the branchial slits, they pass
downwards, and open below into the pericardial cavity (figs.
10-14 and 15-18).

The first change which is apparent is that the walls gradually
come together, from above downwards (fig 12), so that the
cavity is obliterated, and the inner wall thickens, the outer
remaining a single layer of cells. Their lower ends separate
from the pericardium by stage N, and they may then be called
(provisionally) the branchial muscle-plates. According to.
Balfour, they are the myotomes of the head, homologous with
those of the body; whilst according to v. Wijhe they are
visceral plates (Seitenplatte); but a discussion as to their
morphological value may best be left until further on.

Immediately after the branchial muscle-plates have separated
from the pericardium, their ventral ends are divided off from
the remainder of the muscle-plate, and form the coraco-
branchiales (figs. 21 and 22) which grow downwards and back-
wards (fig. 23), until their hind ends become attached to the
shoulder-girdle, just outside the insertion of coraco-hyoideus
and coraco-mandibularis.

The remainder of the branchial muscle-plate develops into
the (branchial portion of the) superficial constrictor, the
adductors, interarcuales, and interbranchiales. The three latter
series of muscles are formed by ingrowths from the muscle
plates, beginning even before they separate from the peri-
cardium (fig. 12). In the 5th branchial segment—where no
branchial cartilages are formed—the branchial muscle-plate is
converted solely into the superficial constrictor.

Two further changes occur in the superficial constrictor ; the
dorsal ends grow upward, and become attached to’ the outer
surface of the trunk myotomes (fig. 26), which have by this
time overlapped the branchial region dorsally, and the lower
ends grow downward, round and outside the ventral longitu-
dinal muscles (7.e. the coraco-mandibularis, coraco-hyoideus, and
coraco-branchiales) and meet in the mid-ventral line (fig. 26).

_ DEVELOPMENT OF HEAD MUSCLES IN SCYLLIUM CANICULA. 79

_ The hyoid section of the head-cavity presents, in stage H, a

. a directed upper end (over the top of the hyomandibular
___ gill-cleft), continuous below with a cavity extending down

____ between the hyomandibular and hyobranchial gill-clefts (fig. 1),
___ as described by Balfour.
_ The anterior part of the upper end begins to be constricted

a off towards the end of stage H, so that by stage I there are

two epithelium-lined cavities lying at the top of the hyoid

ee segment, of which the posterior is continuous with the remainder

of the hyoid head-cavity (figs. 2 and 3).

The anterior vesicle then completely separates, and grows
forwards and inwards (figs. 5 and 9), and forms, as described
by v. Wijhe, the external rectus muscle of the eye.

After the separation of the forepart of its upper end, the
inner wall of the hyoid head-cavity thickens, whilst the outer
remains a simple layer of cells. The cavity is thus obliterated,
from above downwards, and the resulting solid strip of cells is
converted into muscles, the upper portion forming the dorsal
___ portion, and the lower the ventral portion, of the hyoid super-
_ ficial constrictor (figs. 19 and 20). Some of the fibres of the
dorsal portion are inserted into the outer surfaces of the
hyomandibular and cerato-hyal cartilages (fig. 25). The ventral
ends of the lower portions of the hyoid superficial constrictor,
ie. of that below the cerato-hyal cartilages, unite in the
mid-ventral line, below the ventral longitudinal muscles
(fig. 20).

The mandibular head-cavity is described by Balfour as spatu-

late in the early stages; there is a dilated upper portion, pro-

duced ventrally into a long thin process parallel with and in
front of the hyomandibular cleft (figs. 4-7 and 9). This
condition lasts until stage M, when the dilated upper end
spreads upwards round the eye, its walls collapse, it separates
from the remainder of the mandibular cavity, and is converted,
as stated by v. Wijhe, into the superior oblique muscle of the
eye.

The rest of the mandibular head-cavity undergoes the changes
described by Balfour—the cavity is obliterated by the coming
together of its walls, of which the inner one thickens. It is
converted into three muscles—from above downwards, the

80 MR F. H. EDGEWORTH.

levator maxille superioris,! the adductor mandibule, and the
mandibular portion of the superficial constrictor (figs. 24
and 25). The ventral ends of the constrictors of the two sides
come together in the mid-ventral line (figs. 24 and 25).

The cervical myotomes follow on in direct series with the
brachial muscle plates in stage I. Their position is a dorso-
ventral one. From that time onward they begin to overlap the
branchial region of the head, both dorsally and ventrally, the
shape of the most anterior ones becoming concave with the
concavity directed forward. This process continues until, by
stage O, the upper end of the 1st cervical myotome becomes
attached to the back of the skull (fig. 23). Meanwhile the
ventral ends of the first four cervical myotomes have been
growing forward lateral to the cephalic portion of the peri-
cardium, and by stage M have extended as far as the level of
the 2nd branchial segment (figs. 10-14 and 15-18). By stage
N it is found that ventral ends of the first four cervical
myotomes have separated off from the upper ends, and that the
column of cells so formed has grown still further forwards. Its
anterior portion has split longitudinally, the outer slip is attached
to the basihyal, and the inner to Meckel’s cartilage (figs. 19-21).
The hinder end of the column of cells becomes affixed to the
coracoid element of the shoulder-girdle. The coraco-mandibu-
laris and coraco-hyoideus are thus formed from the ventral ends
of the first four cervical myotomes. Comparison of figs. 10-14,
taken from transverse sections with figs, 15-18 from longitudinal
sections of the same stage, and figs. 19-23 show that their
development has nothing to do with the branchial muscle-plates,
or with the retreat of the pericardium from the first three
branchial segments.

The shoulder-girdle and trapezius muscle are formed very late
in development. The shoulder-girdle is first clearly marked
out in stage P, when its upper end is seen to be opposite the
junction of the 10th and 11th body myotomes. At the same
time the trapezius is first seen—it is formed by delamination of
cells from the upper ends of all the cervical myotomes (fig. 27).

‘ Vetter (Joc. cit.) describes a muscle—the superior mandibular constrictor—
just behind, and having the same origin and insertion as, the levator maxille
superioris ; but I have not been able to clearly distinguish it from the levator in
my sections.

_ DEVELOPMENT OF HEAD MUSCLES IN SCYLLIUM CANICULA. 81

_ In regard to the morphological relationships of the various
muscles of the head, it will be clear from the preceding that the
ventral fibres of the superficial constrictor of the hyoid and
mandibular segments have no representatives in the branchial

| P region ; they are developed from the ventral parts of the hyoid
____ and mandibular head-cavities, from parts which in the branchial
region form the pericardium. The lower portions of the super-

ficial constrictor in the branchial region are derived by down-

EB growth from the branchial muscle-plates. The muscles derived

from the branchial. muscle-plates are represented, in the hyoid
segment by the upper fibres of the constrictor, in the mandibular
segment by the levator maxille Saperiorip and adductor
mandibule.

_The above description of the development of the muscles of

, the head of Scyllium has been given without reference to the

rival theories of aHOeE and v. Wijhe as to their mprpholeien
position.

According to Balfour the ob at ney auiaied between the
gill-clefts are homologous with the muscle-plates of the body,
and are somatic structures; whilst v. Wijhe holds that they
are splanchnic structures,

V. Wijhe states that there are in stage I myotomes existing
above these muscle-plates. Of these he says that there is, in
the mandibular segment one, which becomes the superior
oblique; in the hyoid segment two, of which the’ anterior
becomes the external rectus, and the posterior atrophies ; in the

. 4 : Ist branchial segment one, which atrophies ; in the 2nd branchial
_ Segment one, which becomes very rudimentary; whilst the

myotomes of the 3rd, 4th and 5th branchial segments develop
and form the coraco-hyoideus and (according to the table) the
trapezius,

Now, (1) it has been shown above that the so-called anterior
myotome of the hyoid segment is due to the very early budding
of the anterior part of the top of the hyoid head-cavity, to form
a vesicle the walls of which become the external rectus. In
stage I, at which v. Wijhe’s investigations began, there are two
cavities, the posterior of which is continuous with the rest of
the hyoid head-cavity, but comparison with stage H shows how
this has come about. My observations on this point confirm

VOL. XXXVIL (N.S. VOL. XVII.)—OCT. 1902, 6

82 MR F. H. EDGEWORTH.

those of Balfour and Marshall. (2) I can find no trace of any
structures which first separate off from the top of the muscle-
plates of the hyoid, 1st and 2nd branchial, musele-plates, and
then atrophy or become rudimentary. (3) I have not been able
to find evidence of anything in the 3rd, 4th and 5th branchial
segments corresponding to the three myotomes stated by v.
Wijhe to exist there. Ali I can see there are the usual muscle-
plates, which undergo a development similar to that of the
muscle-plates in the Ist and 2nd branchial segments. (4) The
trapezius, coraco-mandibularis and coraco-hyoideus are formed
from cervical myotomes.

The conclusion is, therefore, that the view of Balfour is the
true one—the branchial muscle-plates, and the similarly
situated portions of the hyoid and mandibular muscle-plates,
are homologous with the myotomes of the body, and are somatic
structures.

The superior oblique and external rectus muscles are
specialised portions of the mandibular and hyoid myotomes
which separate, the former late, the latter very early in develop-
ment, from the upper ends of their respective myotomes.

The muscles developed from the premandibular segment are
probably to be regarded as somatic structures, whilst the
ventral portion of the premandibular head-cavity which meets
its fellow just above the pituitary involution (and which atrophies
as v. Wijhe showed) represents a splanchnic element. This
conclusion is supported by consideration of the structure of the
ili nerve.

There are thus in the head of Scyllium eight mesoblast seg-
ments which develop as shown in the following table.

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84 MR F. H. EDGEWORTH.

It follows from the above that the gill-clefts are endoderm
pouches projecting to the exterior between the myotomes of the
head.

Figs. 28 and 29 are diagrams representing these views—
they show how the body-cavity, formed by splitting of the
mesoderm plate, develops somewhat differently in the head and
trunk, how the myotomes are formed, and how the lessened
extent of the body-cavity in the head (ie. the cephalic portion
of the pericardium) as compared with that in the trunk may be
correlated with the presence of gill-clefts in the former.

A distinction, based on v, Wijhe’s work, has been drawn by
Ahlborn! between a branchiomeric and a mesomeric segmenta-
tion in the head. Such a distinction, however, cannot be made,
for, as shown above, these segmentations are one and the same.

This distinction, too, of a mesomeric and _ branchiomeric
segmentation in the head, and the absence of somatic elements
in the mid region of the head, have been used by Gaskell? in
favour of his theory of an arthropod ancestry for, vertebrates.

The failure of such a distinction, and the presence of somatic
muscles in each segment of the head, as shown above, might
however be employed as arguments against such a theory.

Some deductions as to the nature of some of the cranial nerves
may be drawn from the above. The superior oblique and
external rectus eye-muscles are separated and specialised portions
of the myotomes of the mandibular and hyoid segments. The
nuclei of iv and vi nerves therefore may be regarded as detached
portions of the somatic motor nuclei of the v and vii nerves
respectively.2 There is another interesting fact which bears
on these genetic relationships. In the dog the somatic
muscles innervated by the v and vii nerves (with the possible
exception of the anterior digastric) have no posterior root- eangtion
fibres* The superior oblique and external rectus ‘muscles,
then, in also possessing | this peculiarity, resemble the myotomes

1 ** Ueber die Soemiatnes des Wirbelthierkorpers,” Zeitschrift fiir Zoologie,
vol. 40, 1884,

2 This Jowrnal, vol. xxxiii.; 1899.

8 This conclusion has aiveedy been drawn by Marshall (loc. cit ) in the case of
the vi nerve, which, he says, may be regarded as an anterior branch of the vii
nerve.

+ This Journal, vol. xxxiv.

ee hl
- ?

_ DEVELOPMENT OF HEAD MUSCLES IN SCYLLIUM CANICULA. 85

from which they have sprung. The conclusion that the rouscles

: developed from the premandibular segment are somatic in
nature is supported by the facts, that they have no posterior

root-ganglion fibres, and that the nerve fibres passing to them

a have a large maximum diameter—resembling in both particulars
ee the myotomes of the mandibular and hyoid segments.

YV. Wijhe based the following laws on his views of the de-
velopment of the Elasmobranch head-muscles: “Die dorsalen
Wurzeln sind nicht nur sensitiv, sondern innerviren auch die
aus den Seitenplatten, nicht die aus den Somiten stammenden
Muskeln;” and “Die ventralen Wurzeln sind motorisch, inner-
viren et auch die Muskeln der Somite, nicht se eo der
Seitenplatte. ‘

Insomuch, however, as somatic muscles are developed in each
segment of the head of Scyllium, it is clear that these laws will
not hold. Thus the v, vii, ix and x nerves contain motor

fibres to somatic muscles, though having dorsal superficial

origins. In this respect Scyllium resembles the Newt and
Toad. |
~ On comparison of the muscles developed from head-segments
in Elasmobranchs, Amphibia, and Mammals, the chief differ-
ences are seen to lie in the development of new splanchnic
muscles in all the segments other than the premandibular, and
in the disappearance of somatic muscles behind the hyoid
segment; and there are correlated changes in the motor nuclei
of the hind-brain. This is primarily dependent on different
methods of breathing and taking food.

A short comparison may now be made between the develop-
ment of the head-cavities in Scyllium and Triton.’ :

In following the development of the head-muscles in the
Toad and Newt (Joc. cit.), I did not investigate the formation

of the eye-muscles, and restricted the account to the muscles

1 This Journal, vol. xxxvi., 1902,

?The method employed in numbering the head- -segments of the newt and
toad (loc. cit.), based on a (partly erroneous) conception of v. Wijhe’s views, is
a wrong one. In these animals there are but 7 mesoblast segments in the
head, of which the mandibular is the 2nd; the difference from Scyllinm being
that the 5th branchial is absent. As, however, in those papers it was also
stated from what gill-arch segment (¢.g. 1st branchial) each muscle was developed,
the difficulty in comparing the results there given with these is not very great.

86 - MR F, H. EDGEWORTH.

of the gill-arches. Since seeing what happens in Seyllium, I have
found that a similar development of the eye-muscles takes place
in those animals; but as the evidence I have is not quite con-
clusive, I must postpone giving a description and figures.

The method of formation of the head-cavities, the develop-
ment of the cephalic portion of the pericardium, and its
gradual retreat from the anterior branchial segments, the
method of formation and detachment from the pericardium of
the myotomes, are exactly the same in Triton and Scyllium.
Up to the condition shown in fig. 29 the changes are identical.
But from that point development proceeds along diverging
paths, so that the final condition is very different in the two
animals. The details may be readily seen on comparison of
the tabular statement in this. paper with that previously given
for the Newt and Toad. One important point of difference may,
however, be considered in detail. In both Seyllium and the
Amphibians there are a lateral and a median series of ventral
longitudinal muscles. In Scyllium the former (ae. the coraco-
branchiales) are derived from head-myotomes, amd the latter
(i.e. the coraco-mandibularis and coraco-hyoideus) from body-
myotomes, On the other hand, in the Amphibians both series—
the lateral (7.e. the longitudinal muscles of the branchial arches)
and the median (i.e. the geniohyoid, ventral longitudinal muscles
of the neck and the ventro-lateral muscles of the trunk)—are
developed from head-myotomes. !

The development of the head-muscles of Scyllium thus con-
firms the statements made in describing that of the Newt and
Toad. Further, it supports, from the standpoint of compara-
tive anatomy, the views put forward as to the morphological
position of the head-muscles of the dog, and so the truth, for
all the muscles of the head, of Gaskell’s generalisation! that
the motor fibres of somatic and cross-striped-visceral muscles
have different maximum diameters.

1 Jour. of Phys., vol. ix.

Journ. of Anat. and Physiology, Oct. 1902.) [PLate IV.

Fie, 4.

Mr F, H. Epceworrn on Head Muscles in Seylliwm canicula.

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Journ. of Anat. and Physiology, Oct. 1902.)

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Fie. 9,

Mr F. H. Epceworrn on Head Muscles in Seyllium canicula.

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Journ. of Anat. and Physiology, Oct. 1902.

Mr F. H. Enceworrnu on Head Muscles in Seyllium canicula,

Journ. of Anat, and Physiology, Oct. 1902.) [Pare VIL.

= iLa«
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Fic. 18.

Mr F, H. Epceworrn on Head Muscles in Seyllium canicula,

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Mr F. H. Evceworru on Head Muscles in Seyllium canicula.

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Mu F. H. Epgewoxrn on Head Muscles in Scyllium canicula,

Journ. of Anat. and Physiology, Oct. 1902.) 0 [Puare X.

; Fic. 28.

Fic, 29.

Mr F. H. EpGrworrn on Head Muscles in Seyllium canicula,

_ «DEVELOPMENT OF HEAD MUSCLES IN SCYLLIUM CANICULA. 87

TABLE OF FIGURES. Puates IV.—X.

Fig. 1. Longitudinal vertical section, stage H.
Figs. 2 and 3. Longitudinal, stage I,—2 is the more external.
Fig. 34. Transverse section, stage J.

Figs. 4-7. Transverse sections, stage K,—4 is the most anterior ;
- the left side is a little posterior to the right.

Figs. 8-9. Longitudinal vertical sections, stage K,—8 is the more

Figs 10-14. Transverse sections, stage M,—10 is the most anterior ;
in 10 and 11 the left side is a little anterior to the right, in 14 the
left side is a little posterior to the right.

Figs. 15-18. Longitudinal vertical sections, stage M,—15 is the
most external. ‘ '

Figs. 19-22. Transverse sections, stage N,—19 is the most anterior,
the left side is a little posterior to the right.

Fig. 23. Longitudinal vertical section, stage O,

Figs. 24-26. Transverse section, stage P,—-24 is the most anterior ;
the left side is a little anterior to the right.

Fig. 27. Longitudinal vertical section, stage P.

Fig. 28. Diagrams to show formation of body cavity and myotomes
in the trunk,

Fig. 29. Diagrams to show formation of cephalic portion of peri-
cardium and myotomes in the head. A represents the mandibular
and hyoid segments, B the branchial segments. In B the left side of
the section is supposed to pass intersegmentally to show the gill-cleft.

INDEX,

Add.mand,, adductor mandibule.
ant.card.v., anterior cardinal vein.
aud.v., auditory vesicle.
aur., auricle of heart.
B., brain.
b.c., body-cavity.
B.H., basihyal cartilage.
b.br.3, 3rd basibranchial cartilage.
br.1, 1st branchial cartilage.
br.add., adductor arc, viscer.
br.l.aor.ar., 1st branchial aortic arch.

88 DEVELOPMENT OF HEAD MUSCLES IN SCYLLIUM CANICULA.

br.1.cons., 1st branchial superficial constrictor.
br.1.cor.br., 1st branchial coraco-branchialis.
br.1.gc., 1st branchial gill-cleft.
br.1.h.c., 1st branchial head-cavity. .
br.interarc., interarcualis,
_ceratohy.; ceratohyal cartilage: |) |.
cons., superficial constrictor. _
cor.hy., coraco-hyoideus. 7 Eee
cor.mand,, coraco-mandibularis. pe @
cor.mand, and cor.hy., united coraco-mandibularis and -hyoideus,~

dor.aor., dorsal aorta. '- Liat’ :

Duct.endo., ductus endolymphaticus,

- hy.ue., hyoid head-cavity. =
hy.d.cons., hyoid dorsal constrictor. hey
hy.v.cons., hyvid ventral constrictor.
hyobr.g.c., hyobranchial gill-cleft. | Bhi ae

~hyomand., hyomandibular cartilage. =a: PS re

hyomand.g.c., hyomandibular gill-cleit. ‘it A BPs
L, liver. .
‘ lat.x., lateral line branch of' vagus.

lev.maz.sup., levator maxillee superioris. Rat Vw te er ois

mand.cons., mandibular constrictor.
mand.h.c.. mandibular head-cavity. RE Oar,
Me., Meckel’s cartilage: '\**°s"0') 'S))sis"@ GaSe ae
my., myotome. . . feos
par.ch., parachordal cartilage.
f. * «5» per., cephalic portion of pericardium. - =
pl.pt., palato-pterygoid bar;
premand.he., premandibular head-cavity.
sh.gird., shoulder-girdle,
spl.m., splanchnic muscle.
thy., thyroid gland.
trap., trapezius
tr.my., myotome of trunk.
vent., ventricle of heart.
vent.aor., ventral aorta,
V.e.mand,, mandibular branch of v nerve.

University College, Liverpool.

* THE following is a description of an Australian skeleton

presented to the Anatomical Museum of University College,

Liverpool, by Mr C. H. Robinson.

Nothing is known regarding the source of the skeleton, nor
the particular tribe to which it belonged.
_ The bones are small and slender, but well formed. They
are probably those of an aged female about 4 ft. 6 ins. in

ight.

In this description considerable help has been derived from
the “Challenger” Reports of Sir William Turner (1), whose
methods for obtaining the various indices and measurements

have been followed.

VERTEBRAL COLUMN.
Vertebral formula C, T,, L; 8; Co. (?).
The Cervical Vertebre are small but well formed. Excepting the

first, sixth, and seventh, the spinous processes are strongly bifid.
The Thoracic Vertebrz are normal, except that the ninth articulates

with the heads of two ribs. .

The Lumbar Vertebre all show well-marked mammillary processes,
and except the first, exhibit traces of an accessory process.
The lumbar indices are :—

120
1133
L, 109-5
L, 109-1
L, 90-1

The lwmbo-vertebral index is 1064. The average lumbo-
vertebral index amongst Australians is 107°8 (Cunningham)
(3). This index, which is the relation of the sum of the anterior
measurements of the lumbar bodies to the sum of the posterior
measurements, has an important bearing on the /wmbar curve.

_ Professor Cunningham (3) in his paper on the Lumbar Curve
shows that a high lumbo-vertebral index is characteristic of
the lower races and also of the higher apes,

90 MR W. H. BROAD.

The following table is taken from the above-mentioned

paper :—
LuMBo- VERTEBRAL INDICES.

Negro 105°4
Bushman 106°6
Australian 107°8

{ European 95°8
Man ~

j Semnopithecus 105°1
Apes < Gibbon 107°1
Gorilla 108°1

In Europeans a// the bodies of the lumbar vertebrae, except
usually the first, have an index below 100, 22. are longer
anteriorly than posteriorly, and consequently have a lwmbo-

vertebral index of less than 100.
In the skeleton under consideration, the /ifth lumbar vertebra
is the only one with an index below 100, and the lumbo-

vertebral index is 1064.

Fig. 1.—Sacrum of Aboriginal Australian—(Z nat. size).

The Sacrum is a small bone measuring 105 mm. in length and
98 mm. in breadth. (Average Australian length 106 mm., breadth

100 mm.—Turner (1).
The neural canal is roofless except opposite the third and fourth

THE SKELETON OF A NATIVE AUSTRALIAN. | 91

ra, which possess rudimentary spines. There are three well-
marked depressions on the first three vertebre for ligamentous

attachment, of which the first is the deepest.

The first, second, and a small part of the third vertebra form the

auricular surface, which is notched a little below its middle.

Sacral Curve-—The anterior surface of the sacrum shows a
remarkably shallow curve. The greatest depth of this concavity
is opposite the body of the third sacral vertebra, and measures

11mm.

o~_— eee ees eee ee ee

eee eee eee

Fie. 2.—Sacral Curve in Aboriginal Australian—(nat. size).

The average maximum depth in Australian sacra is 161 mm.
(Paterson) (2).

The curve is more marked below than above the deepest point.

Sacral index.—The sacral index is 93°4 (dolichohieric).

92 MR W. H. BROAD.

In Sir W. Turner’s tables the Australian sacral index (eight
cases) varies from 93 in the Perth tribe to 104 in the; Riverina
Australian,
In Professor Paterson’s table (eight cases) the average is 106.
Obviously the sacral index must always vary with the
curvature, and in this case a low index and a shallow curve are
associated together.

The Jnnominate Bones are small, and the expanded ilia, triangular
thyroid foramina, and everted lips of the pubie arches clearly
demonstrate female characteristics. Muscular impressions are poorly

marked, e.g. the curved lines, and the ilio-pectineal eminences are
~ exceedingly slight and smooth.

The thyroid foramen is-triangular, and the vertical diameter of the
foramen exceeds the transverse,—a female characteristic (Turner).
The cotyloid notch of the acetabulum is unusually wide.

Indices of the Innominate Bones.
Australians (Turner).

1. Innominate index ... R. 73 L. . from 76 to 83
2. Iliac index .... a R105 L. 111... (eee
3. Ischio-innominate index R. 31 L. 29... ,, 40 ,, 46
4. Pubo-innominate index R. 51 L. 50... ,, 40 ,, 48

It will be seen that in the first three of the above indices
these innominate bones are considerably below the Australian
standard as given in Sir W. Turner’s tables. This is accounted
for by the fact that the bones possess an unusually long and
narrow ilium.

At the same time the pubo-innominate index is above the
standard.

Now the pubo-innominate index shows the relation of the
os pubis to the breadth of the innominate bone, so that in this
case the pubis contributes more than is usual to the width of
the os innominatum.

Femur.—Mazximum length, R. 372 mm., L. 375 mm. (Average
Australian 452 mm. [Turner].)

Maximum trochanteric length, R. 362 mm., L. 364 mm.

The difference between the maximum length and the maximum
trochanteric length determines the amount of obliquity of the neck.

In the present instance the difference amounts to 10 and 11 mm.
respectively, showing an increase in the angle over the normal.

The shaft of the femur is slender, and exhibits only slight muscular

THE SKELETON OF A NATIVE AUSTRALIAN. 93

impression. It also shows the characteristics of Broca’s ‘femur a

A feeble trochanter tertius is present on the left femur, and the
right gluteal ridge is prominent.

The upper part of the shaft is flattened from before backwards
and bulges outwards, a character noted by Sir W. Turner both in
Australians and New Zealanders. The shaft presents a marked
convexity forwards and is somewhat twisted outwards. The spiral
line is absent, but in a situation corresponding to the position of its
upper end there is a prominent tubercle. On the upper surface of the
posterior portion of the internal condyle there is a well-marked
articular facet (6). This will be referred to later.

The popliteal surface is slightly convex from side to side.

_ Popliteal_ indices, R. 92, L. 96. (Average Australian index 94,—
Hepburn) (7).

—Length, R. 312, L. 310. (Average 375 mm.,-—Turner.)

‘This slight inequality in length compensates for the unequal
length of the femora.

‘The tibia is platyknemic ; the head is placed obliquely, the articular
surfaces looking upward and backward ; the external articular surface
is convex from before backwards ; and on the anterior surface of the
inferior extremity there is an articular facet (5), continuous with the
inferior articular surface, which articulates with the astragalus.

length of tibia x 100
length of femur )

The Tibio-femoral index (
is R. 83, L. 82.

‘These indices correspond with the mean of six Australians measured
by Sir W. Turner, which was 82°9.
"He places the Australians amongst the dolichoknemic, or long-

legged series.

The height of an individual equals twice the combined length
of the femur and tibia (Turner). In the present instance that
would be F. 372 + T. 312 = 684 x 2 = 1368 mm., or about 4 ft.
6 ins. This is considerably below the average height—5 ft.
5 ins.—assigned to Australian races in the tables of racial
stature (8).

Fibula.—Length, R. 303 mm., L. 302 mm. The fibula is small,
slender, flattened from side to side, and presents a convexity inwards
and forwards.

There is a large surface for the attachment of the tibialis posticus.

Uprrer Lixs.

Clavicle.—Length, R. 110 mm., L. 10S mm, (Average 142 mm.)
The surfaces are smooth, muscular attachments being feebly

94 MR W. H. BROAD.

developed, whilst ligamentous impressions are well marked. The
subclavian groove is absent.

Seapula.—Length, R. 108 mm., L. 112 mm. Breadth, R. 76 mm.,
L.78 mm. (lurner’s average Australian, length 150 mm., breadth
100 mm.)

Scapular index, R. 70, L. 69°5. (Average 66.) The scapula is
long and narrow, and the suprascapular notch is absent.

Humerns.—Length, R. 266 mm., L. 256 mm. (Average 300 mm.)
Sir W. Turner’s Australians, with one or two exceptions, had the
right humerus slightly longer than the left. He mentions an
unusually large disparity between the length of the right and left
humeri of an Australian female, which amounted—as in this case—to
10 mm. The musculo-spiral groove is absent, the radial depression
is well marked.

Radius.—Length, R. 200 mm., L.198 mm. The pronator impres-
sions are well marked. The lower extremity is bent forwards con-
siderably.

length of radius x 100

rie lj oF
Radio-humeral index lesa it baaiaree

= R.75,L. 76.

These correspond with the mean given by Sir W. Turner,
which is 76 (mesatikerkic).
The average European index is 72°4 (brachykerkic).

Ulna.—Length, R. 220 mm., L. 219 mm. The greater sigmoid
cavity is peculiar, being directed mainly outwards, and only slightly
forwards. The lesser sigmoid notch is absent, the side of the radial
head articulating with the lower and external portion of the greater
notch.

The habitual attitude would appear to have been one of semiflexion
and semipronation of the forearm.

(humerus + radius) x 100
femur + tibia \

Intermembral index = |
R. 68:1, L. 68°6.

The indices in Sir W. Turner’s Australians varied from 67:4
to 72.

SKULL.

The measurements compared with those of Australian skulls from
the tables of Sir W. Turner and Topinard (4) :—

Turner. Topinard.

Antero-posterior diameter ... 166 mm, ... 173-192
Transverse ‘a web RS: 5) ote
Vertical a EPR 1 | aber ania

Cephalic index ie woe (34 .-. 68-72 71:4

Vertical _,, ey we TEL . 65-72

THE SKELETON OF A NATIVE AUSTRALIAN. 95

Turner. Topinard.

| Facial index os <3 °685°2 a : 56°6

Nasal ee .. 50-56 —-53°3
Orbital, Ore paar: Cane oo eaage 7
Capacity (millet seed) ... 114I-6c.c. ... 998-1330 1181 F.
as 1347 M.

The skull is dolichocephalic, microcephalic, prognathous, and

e.

Tt is, however, of larger capacity and less dolichocephalic than
usual amongst Australians. Viewed from in front, the cranium has a
‘keel-shaped ’ appearance.

Teeth.—Dentition is complete. The molars are worn and flattened,
and several teeth in the upper jaw are carious.

The lower jaw is a small but thick and powerful bone; the rami
are short and broad, and the genial tubercles prominent.

Summary.—The chief points of interest about the skeleton
{ and skull are—
J, The small size of the bones.

2. The shallow sacral curve, and the notched auricular
surfaces.

3. A narrow ilium associated with a long and narrow os
pubis.

4. The characteristics of the bones of the lower limbs,
peculiar to those races accustomed to the “squatting” posture,
described by Thomson and Charles.

These are—a facet on the upper and posterior surface of
the internal condyle of the femur; the obliquely placed tibial
head; the convexity from before backwards of the external
condylar surface of the head of the tibia; the facets on the
anterior inferior surface of the tibia, and on the upper surface
of the neck of the astragalus; the large surfaces for attachment
of the tibialis posticus on the tibia and fibula.

5. The curious formation of the articular surfaces forming
the elbow and superior radio-ulnar joints.

6. The microcephalic, dolichocephalic, platyrrhine and prog-
nathous character of the skull.

aa ae eee

[REFBRENCEs.

96 THE SKELETON OF A NATIVE AUSTRALIAN.

REFERENCES.

(1) “Challenger” Reports, vol. xvi. (Zoology).—Sir W. Turner.

(2) Scientific Transactions of the Royal Dublin Society, vol. v.,—
“The Human Sacrum.”—Prof. A. M. Paterson, M.D
_ (3) Royal Irish Academy, — Cunningham Memoirs—‘* The Lumbar
Curve in Man and Apes.”—Prof. D. J. Cunnrnenam, M.D,, ¥. eiiin

(4) ‘‘ Anthropology.”—Dr P. Toprnarp.

(5) Journal of Anatomy and Physiology (vols. xxiii, and xxiv.) —
= the influence of posture on the form of articular surfaces of the
tibia and astragalus in different races of man and the higher apes.”
—ArtuuR Tomson, M.A., M.B., &.

(6) Journal of Anatomy and Physiology (vol. xxviii. i) The
Panjabi and Squatting.”—Prof. R. Haverock CHARLES, _

(7) Journal of Anatomy and Physiology (vol. xxxi,)—“ The Trini]
Femur, contrasted with the femora of various savage and civilised
tribes.” —Dr HEPBURN.

(8) Transactions of Anthropometrical Committee, Leste rai
ciation,

a

Ei al |

Hournal of Anatomy and Phpsiolo yy.

ARE THE CRANIAL CONTENTS DISPLACED AND
THE BRAIN DAMAGED BY FREEZING THE
ENTIRE HEAD? By Joxnnson Symineton, M.D.,
Professor of Anatomy, Queen’s College, Belfast. (PLATE XI.)

AmonGst the methods employed in the investigation of the
topographical relations of the various organs of the body, that of
making sawn sections of the frozen subject has been used very
extensively and with great advantage. It is true that this plan
has been, of late years, superseded to a large extent owing to the
discovery of the valuable properties of formo] as a hardening
and fixing agent. There are still, however, various purposes for
which no other method gives such satisfactory results as freezing.
This is particularly the case when we wish to obtain a connected
and continuous view of the structures situated in a series of
parallel planes passing through large portions of the body, such,
for instance, as a number of sagittal sections of the trunk. In
regions where the structures lying in a particular plane vary
very considerably in density and degree of fixation, sections made
with a saw after freezing the parts give better results than
sections made, partly with a knife and partly with a saw, after
hardening in formol.

This is particularly the case with the head where the osseous
tissue is so considerable and irregular in outline that it is
necessary to use the saw for the soft tissues as well as the bones,
although not only the non-osseous structures, but also the bones
in places like the walls of the nose and in the tympanum, do not
eut well with a saw after simply hardening them in formol.

In some recent observations on cranio-cerebral topography
where I desired to obtain the relations of the deep parts of the

VOL. XXXVII. (N.S. VOL. XVII.)—JAN. 1903. 7

98 DR JOHNSON SYMINGTON.

brain to the surface, frozen sections of the entire head afforded,
so far as I was able to judge, reliable and trustworthy data.
The utility of this method has been called in question by
Professor August Froriep,' who, from an examination of published
drawings of such sections, as well as from his own experiments,
has come to the conclusion that during the freezing process the
brain suffers such serious injury and disturbance of its parts as
to greatly impair the value of any deductions drawn from a
study of sections obtained by this method of fixation. Froriep
holds that the displacement of a portion of the skull contents is
a normal concomitant of the freezing of the unopened head, and
it must be admitted that the anatomical relations of the skull
and brain and the changes in volume associated with the freezing
process suggest the probability of such an occurrence.

We may regard the cranium as a box with rigid walls having
only one aperture (the foramen magnum) of any appreciable
size, and through which some of the cranial contents might be
forced. All the other cranial openings are not only much
smaller, but they are practically closed by nerves-or other
structures. The contents of this box are the brain, which is a:
large organ of soft consistence, and a variable amount of free
fluid situated between the skull and the brain, or in the ventricles
of the latter organ. Froriep draws attention to the fact that
79 p.c. of the brain weight is estimated to consist of water, and
consequently a brain weighing 1300 grammes would contain
1027 grammes of water. The free fluid in the cranial cavity
may be taken as from 50 to 100 grammes, and we may accordingly
estimate the amount of water in the cranial cavity as 1100
grammes. Water expands when frozen in the proportion of 1
to 1:09, so that the mass displaced from the cranial cavity during
the freezing of an unopened head ought to be 99 grammes. In
a female subject aged 39 years Froriep calculated that the mass
actually expelled from the cranial cavity during the freezing of
the head amounted to 30 grammes or less than 4 of the amount
that might theoretically be expected. From Froriep’s account
of this experiment it would appear that the mass protruded was

1 “Ueber ein fiir die Lagebestimmung des Hirnstammes im Schiidel verhiing-
nissvolles Artefact beim Gefrieren des menschlichen Cadayers,” Anatomischer
Anzeiger, Bd, xix., 1901.

ARE CRANIAL CONTENTS DISPLACED BY FREEZING ? 99

| unusually large, and certainly there is no experimental evidence

to support the view that the expansion of the brain during the

- freezing process i is equal to what it would be if the 79 p.c. of

water in its composition behaved as ordinary water. This water
is probably in intimate chemical union with other substances,
and the resulting compounds may act in a very different manner
from water as regards change of volume during the freezing
process. Further, even in the case of the free water the
substances it holds in solution may influence its change of
volume when frozen. In the present state of our knowledge
we are not justified in assuming that the water in the cranial
eavity will expand as ordinary water does when frozen, and
consequently any objections to the use of the freezing method
in the study of cranio-cerebral topography based on such a

_ supposition must not be admitted without experimental proof.

Froriep holds that his view is supported by the results of a
critical examination of the various illustrations that have been
published of frozen sections of the entire head. He first selects
Pirogoff’s Atlas,| and mentions a number of plates in this
work showing alterations in form and displacements of various
parts of the brain which Froriep believes were due to the
freezing process. One of these plates has been reproduced (fig.
2) in Froriep’s paper. He considers that this figure illustrates
the artificial distortion of the basal portions of the brain,
which, however, had been dammed up below by the early
freezing of the cervical part of the contents of the spinal canal.
If the drawing were a correct representation of the appearance
of the section, I should be willing to agree with Froriep’s
interpretation, but it seems to me that Pirogoff’s plates are so
diagrammatic and inaccurate that they ought not to be accepted
as satisfactory proofs of the existence of such deformities. In
the figure of a median section of the head which Froriep has
reproduced from Pirogoff, the upper four cervical vertebra are
shown with the upper part of the larynx. I assume from its
position that the larynx is represented, but it needs a vivid
imagination to recognise the epiglottis or the superior laryngeal
aperture, and it will hardly be maintained that the freezing

1 Anatome topographica sectionibus per corpus humanum congelatum triplici
directione ductis illustrata, Petropoli, 1859,

100 DR JOHNSON SYMINGTON.

process had altered almost beyond recognition these parts of the
larynx. When the larynx is so badly figured, what reliance can
be placed upon the drawings of the brain ?
Professor:Froriep next refers to Braune’s Atlas,! and selects
Pl. I. and II. which were prepared from median sections of the
bodies of a male and a female subject. He admits that these
drawings give essentially correct pictures of the medulla, pons
and cerebellum free from the characteristic signs of distortion
due to freezing, but the diameter of the medulla and spinal cord
is too great. Froriep enquires how Braune succeeded in obtain-
ing correct pictures from frozen sections, and believes that the
following extract from the text to Pl. I. shows how this was
accomplished :—“ Besondere Miihe erforderte es, die einzelnen
Teile des Gehirns deutlich zur Anschauung zu bringen. Es
mussten Durchschnitte an frischen Gehirnen dazu dienen, die
Zeichnung innerhalb der schon festgestellten Contouren sauber
und deutlich zu machen.” In fig. 3 Froriep gives a copy of the
upper part of Pl. C of Braune’s Supplement? to his large
atlas as an illustration of what he considers to be the usual
appearance of a frozen median section of the head. With
reference to the two plates in Braune’s Topographisch-anatom-
ischer Atlas, I do not think that the text or the appearance of
these plates justify the assumption that Braune corrected the
outline of the various parts of the brain to make them conform
to what his anatomical instincts conceived to be their normal
position. The special purpose of the publication of the plates
in the “Supplement,” was to show the position of the pregnant
uterus and its contents, and it is evident that no attempt was
made to give an accurate drawing of the brain or spinal cord.
When a frozen section is made, particularly such a large one
as a median cut through the entire body, the heat produced by
the friction of the saw causes a partial thawing of the surface,
and any cavities normally occupied by fluid are apt to become
filled up near the surface of the section with sawdust, and
after the section is made the exposed surfaces are covered by a

1 Topographisch-anatomischer Atlas, ‘‘ Nach Durchschnitten an gefrorenen
Cadavern.” Leipzig, 1888.

2 “Die Lage des Uterus und Foetus am Ende der Schwangerschaft. Nach
Durchschnitten an gefrorenen Cadavern.” Supplement zu dem topographisch-
anatomischen Atlas des Verfassers, Leipzig, 1872.

ARE CRANIAL CONTENTS DISPLACED BY FREEZING ? 101

‘more or less thick layer of this dust. In order to define clearly
__ the different structures, it is necessary to wash the surfaces with
__-water and even to scrub them with a nail-brush. If this be
_ done rapidly the surface becomes frozen again in a few
minutes. In the case of the brain and spinal cord, the spaces

usually occupied by the cerebro-spinal fluid are found to contain
more or less of this sawdust-looking material. In such sections
as those of Braune’s the spinal cord is represented as too large ;

_ this I thought was due to the subarachnoid spaces being occupied

by this dust, which presents a considerable resemblance to the

_ naked-eye appearance of a sawn section of a frozen cord., As we

shall afterwards see, Froriep gives an entirely different explana-
tion of the origin of this material.

In his description of a median section of a pregnant woman,
Waldeyer' refers to the imperfect preservation of certain parts
of the brain, and he attributes this to the fact that the body had
been kept for several days during warm weather before being
placed in the freezing mixture. Froriep considers that the
appearances of this brain suggest that it had suffered the usual
changes associated with the freezing process, but he admits that
the liability to post-mortem changes increases the difficulty of
determining the real cause of the damaged appearance of the
brain which may be seen in frozen sections.

Froriep does not mention Macewen’s Atlas of Head Sections
published in 1893, although it contains a more extensive series
of illustrations of frozen sections of the entire head than any
other atlas. This work contains 53 photogravures made from
photographic plates of frozen sections of 7 subjects. The first
13 plates contain a series of coronal sections of the head
of a man aged 60 years. The brain was evidently in a good
state of preservation before being frozen, and I do not think the
sections show any appreciable signs of displacement and injury
to the brain such as Froriep regards as of normal occurrence.
Some of the other series of sections appear to me to indicate
that the subjects had not been obtained with the brain in a well-
preserved condition. In some places the distinction between
the white and grey matter is not well marked, while in others
the brain had shrunk so as to have an abnormally large space

1 Medianschnitt ciner Hochschwangeren bei Steisslage des Fetus, Bonn, 1886.

102 DR JOHNSON SYMINGTON.

between its surface and the cranial wall. In none of them am
I able to detect signs of abnormal expansion of this organ.

According to Froriep, Pl. I. and II. in my work on The
Topographical Anatomy of the Child show, on careful examina-
tion, evidence of displacement of certain parts of the brain due
to the freezing. These plates represent median sections through
the entire trunk of a girl 13 years old and of a boy 6 years old.
Froriep states that they demonstrate that the mid-brain and
the vermiform process had been depressed by the freezing, but
he does not give any reasons for this opinion. He also considers
that the optic commissure had been displaced, and, in support of
this view, refers to the fact that it is shown lying above the
dorsum selle. At the time when these sections were made, the
optic commissure was described as lying against the optic groove
of the sphenoid bone, and I must-admit that although both my
plates show it at a considerable distance from that groove, I did
not detect the discrepancy. Since then this error in our text-
book anatomy has been exposed. Thus, Lawrence? found, on
careful dissection, that in a girl 4} years old the commissure
was placed far back from the optic groove and olivary eminence,
so that a large part of the upper surface of the pituitary body
was visible in front of it; and in a man the commissure almost
entirely covered the pituitary fossa, and its anterior border very
nearly corresponded with the posterior border of the olivary
eminence, but did not touch the latter, and, as in the girl, was
quite removed from the optic groove. According to Zander,’ the
length of the intra-cranial portion of the optic nerve ranges from
6 to 21 mm.; if that be so it is evident that the position of
the optic commissure must also vary. He maintains that the
chiasma never reaches with its anterior border up to the limbus
sphenoidalis, but on an average is about 10 mm. from it. In
two adult subjects in which median sections of the head were
made after hardening in formol, I found the optic commissure
occupying practically a similar position to that figured in my
two piates.

1 “The Position of the Optic Commissure,” Proceedings of the Anatomteat
Society of Great Britain and Ireland, May 1894.

2 “Ueber die Lage und die Dimensionen des Chiasma opticum, w.s.w.,”
Vereinsbeilage d. deutsch. med. Wochensch., 1897.

ARE CRANIAL CONTENTS DISPLACED BY FREEZING ? 103

_ The position of the optic commissure appears to vary according

p to the length of the optic nerves and the amount of cerebro-
___ Spinal fluid in the region of the interpeduncular space. It is
___ often situated some little distance above the pituitary body, and
may be found so far back as to lie vertically above the free

upper edge of the dorsum sell. It thus appears that the
situation of the optic commissure as shown in my PI. I. and

II. cannot be advanced as a proof of the displacement due to

In the whole literature of this subject only one figure of a
frozen section of the head is known to Froriep which does not
show undoubted artefacts due to freezing. This is a drawing by -
Axel Key and Retzius! of a median section of a head made after
injecting the subarachnoid space and the ventricles. Froriep
admits that certain parts of the brain are not quite normal, but
he considers this to be due to the pressure of the material
injected. In his opinion the most surprising thing in this case
is that the pons and medulla occupy their natural position.

Enough has been already said to show that we do not agree
with Froriep’s contention that all the published plates of frozen
sections through the unopened head (except the last mentioned)
show distinct and undoubted signs of cerebral displacements.
He is on firmer ground when he bases his opinion on the results
of his own observations and experiments. These results in some
cases are very surprising, but coming from an anatomist with
such a high reputation as an accurate and a keen observer, they
demand very careful consideration.

Froriep’s attention appears to have been first diveoted to this
question during the examination of a series of horizontal sections
of the neck and thorax of a male subject aged 26 years. In
these preparations the spinal cord was surrounded by an
irregular whitish mass, which he found to consist of white and
grey brain substance filling the dura mater sheath down to the
level of the 5th dorsal vertebra. In another subject, a male
21 years old, the medulla and the spinal cord as far as the 4th
cervical vertebra were surrounded on all sides by this material,
and from this point to the 12th dorsal vertebra the spinal cord

1 Studien in der Anatomie des Nervensystems wnd des Bindegewebes, erste
Hilfte, Stockholm, 1875, Tafel vii. fig. 1.

104 DR JOHNSON SYMINGTON.

was pressed towards the dorsal side of the spinal canal, while on
its ventral side this brain material varied in thickness from 4 to
8mm. Ina frozen head which had been separated from the
body, the spinal cord had bulged beyond the plane of the section
through,the neck. As in this case the vessels were filled with
a turpentine and linseed oil paint injection, which process may
have injured the parts, a fresh uninjected subject was selected
and the head frozen after cutting through the neck between the
4th and 5th cervical vertebre. At first the cut surface of the
spinal cord was in the same plane as the divided vertebral
column. After being in the freezing mixture for seventeen hours
the spinal cord projected 3 mm. from the spinal canal, and five
hours later a cylindrical mass 10 cm. long protruded beyond the
vertebral canal. On median section the specimen presented
appearances indicating that the lower parts of the brain had
been pressed down and portions of it damaged. The pons was
flattened against the base of the skull so as to reach down to
the foramen magnum, and the hinder part of the thalamus and
the mid-brain were depressed, while the inferior vermiform
process, as well as the lower part of the lateral lobes of the
cerebellum, had been displaced downwards in a much injured
condition through the foramen magnum into the vertebral canal.
In order to see if. this expansion and consequent injury and
displacement of the brain could be avoided by hardening the
brain before freezing by injecting a fixing fluid, Froriep injected
a 10 p.c. solution of formol into the vessels of a very fresh
subject, and the freezing was not commenced until the tissues
were well fixed by the formol. When the specimen was removed
from the freezing mixture and examined, it was found that the
spinal cord had not protruded beyond the cut surface of the
neck, and it looked as though the previous fixation with formol
had prevented the expansion of the brain during the freezing
process. When, however, a median section of the frozen head
was made, it was discovered that part of the base of the skull
above the nasal cavities had been fractured and depressed, and a
portion of the right frontal lobe of the brain pressed into the
upper part of the nose, the ethmoidal cells, and even the frontal
sinus.

In Froriep’s experience the axial portions of the mid- and

ARE CRANIAL CONTENTS DISPLACED BY FREEZING ? 16

: ahibbenin usually suffer more severely from the freezing than
a _any other parts of the brain, and he explains this on the suppo-
sition that they are the last parts of the cranial contents to freeze,

and are consequently compressed and displaced by the expansion

of the more superficial portions of the brain, which freeze sooner.
In the case of the formol-hardened brain, Froriep supposes that
_ the neck was frozen earlier than usual and thus filled the upper
part of the vertebral canal with a firm resisting mass. Under
_ these conditions the expanding brain had broken the weak
anterior part of the base of the skull and forced the adjacent
portion of the brain out of the cranial cavity.

While readily admitting the interest and importance of
Froriep’s results, I felt that they were so opposed not merely to
“my own experience, but also to the published results of other
workers, as to require further observations before being accepted
as of normal and regular occurrence. Nearly all my frozen
sections were made previous to the publication of my work on
The Topographical Anatomy of the Child, which appeared in
1887, and with but few exceptions the brains of these specimens
have not been preserved until the present time. More recently,
however, I have prepared and studied carefully a series of frozen
sections of the head of a female, which was hardened in formol
before freezing, and since then has been carefully preserved in
that fluid) The specimens and photographs of the sections were
shown to the members of the Anatomical and Physiological
Section of the Royal Academy of Medicine in Ireland, in Feb.
1896 (see Proceedings of this Academy, vol. xvi. p. 407).
After reading Froriep’s paper I decided to carefully examine
these preparations to see whether or not the section showed
those artefacts which were to be expected from Froriep’s
observations. The head has been divided by horizontal cuts
into six slabs, and so far as the surfaces of these slabs were
concerned, I could find no indication of such displacement or
injury, either to the brain or the skull. As, however, Froriep
refers frequently to the appearances of median sections of the
lower parts of the brain, I cut in this plane three of the slabs
4Nos 3, 4, and 5) which contained the mid-brain, pons cerebellum
and medulla, and took a photograph (see Pl. XI.) of the left
halves of these slabs after placing them in their proper relation

106 ARE CRANIAL CONTENTS DISPLACED BY FREEZING ?

to one another. All the sections of this head, as well as photo-
graphs of both the horizontal and sagittal sections, were ex-
hibited at a meeting of the Anatomical Society of Great Britain
and Ireland in June 1902.

On comparing the divided parts of the brain seen in Pl. XI.
with similar sections made on brains hardened and cut i situ
without freezing, I could discover no essential differences in
position or general appearance. In my view it is more normal
than the plate in Axel Key and Retzius} which Froriep regards.
as free from any artefact due to the freezing. In their section
the direction of the posterior part of the corpus callosum is
quite different from that usually seen. They show the splenium
directed nearly straight back, whereas it is almost invariably
turned more or less directly downwards. Again, the lower end
of the pons reaches within a } of an inch of the anterior edge of
the foramen magnum. It is true that in my specimen the
lateral lobes of the cerebellum reached into the foramen magnum,
but that is frequently seen in unfrozen heads, and cannot be
regarded as a proof of the cerebellum having been forced down
by the pressure of the brain tissue above expanding as it froze.

The method I adopted in the preparation of my specimen was
as follows :—The entire body was hardened by the injection of a.
strong solution of formol, the neck divided opposite the 5th
cervical vertebra, and the head again injected, but this time
through the carotids and with a solution of gum; the head was.
put into a wooden box just large enough to hold it, the
box was filled with gum solution, and the closed box kept in a
freezing mixture until well frozen. The box was then fixed in a
frame and sawn across along with its contents.

I am not prepared to explain why Froriep’s results differ from
my own, but I am satisfied that the brain in my specimen did
not suffer any appreciable displacement or injury as the result of
the freezing process to which it was subjected, and I think this.
opinion is supported by the photograph on Pl. XI. which was.
made from my untouched life-size negative.

1 Op. cit.

(Pirate XI.

AND PuysIOLoGy, Jan., 1903.]

Journ. OF ANAT.

SYMINGTON

PROFESSOR

ON THE DEVELOPMENT OF THE PTERYGO-QUAD-
_ RATE ARCH IN THE LACERTILIA. By R. Broow,
MD. BSc, CMZS.

TuE development of the pterygo-quadrate arch in Sphenodon has
recently been carefully worked out by Howes and Swinnerton
(1), who have shown that in this primitive reptile the arch in its
early condition is present as an irregular cartilage, shaped
somewhat like a broad capital H. Of this the anterior part
represents the epipterygoid and the pterygoid process, while the
posterior portion and most of the cross bar represent the
quadrate.

In the lizard, while the epipterygoid closely resembles that in
Sphenodon, the quadrate differs in having, at least in the later
stages of development, no connection with the epipterygoid, and
not even a trace of an anterior process. Parker (2) failed, in
working out the development of Lacerta, to find any connection
between the quadrate and the epipterygoid, even in the early
stages; and Gaupp (3), who appears to have been the only later
worker at the subject, has also failed to demonstrate any
cartilaginous connection between the two elements.

Believing that the lizards are the immediate descendants of
forms moderately closely related to Sphenodon, I thought it
probable that a connection between the epipterygoid and the
quadrate would be found in the embryos of at least some lizards,
even though it might be lost in Lacerta. I therefore made an
examination of embryos of as many different Lacertilian types
as I have at present at hand. These include members of the
Agamide, Zonuride, Lacertide, Scincide, and Chameleontide.
Of each of the types, I have examined embryos of a stage
corresponding to stage Q of Howes’ and Swinnerton’s Sphenodon
paper. This stage represents that in which membrane bones
_ have commenced to ossify, and in which most cartilaginous
_ structures are for the first time fully chondrified. It is also the
stage in which ancestral structures which may completely
degenerate in later ontogeny, are most likely to be found ina

108 DR R. BROOM.

well developed condition. In all the types which I have
examined I have found evidences of a connection between the
quadrate and epipterygoid, and in three of them the connection
is present as a well chondrified bar.

Zonuride (type, Zonurus polyzonus, Smith, fig. 2).—In the
embryo Zonurus the condition of the pyterygo-quadrate arch at
stage Q bears a marked resemblance to that of Sphenodon (fig. 1).

Fic. 1.—The mandibular and pterygo-quadrate cartilages of an embryo (stage Q)
of Sphenodon punctatus, Grey (after Howes and Swinnerton). x 14.
Fie. 2.—Ditto of embryo (stage Q) of Zonwrus polyzonus, Smith. x 24.

The epipterygoid, ep., is present as a rounded, moderately
straight cartilaginous rod; at its lower end it curves forwards,
and is continued into a well developed cartilaginous pterygoid
process, pt, which rests on the pterygoid bone, and is more than
half the length of the epipterygoid. From the base of the
epipterygoid there runs backwards and slightly downwards to
near the lower end of the quadrate a rounded cartilaginous bar
of about the same thickness as the epipterygoid. The posterior
end of this connecting bar is slightly dilated, and is fixed to the
quadrate, gw, on its inner side, a little above the articular end.
The quadrate itself is moderately long and slightly curved, and
is directed well backwards. It is moderately round in section,
but from the outer and upper side of the anterior half there
passes upwards a small flattened ridge. The articular surface
for the lower jaw looks almost as much inwards as downwards.

Lacertide (type, Hremias capensis, Smith, fig. 3)—In the
embryo Eremias at stage Q, the epipterygoid, ep, is long and
slender. It is directed upwards, backwards, and slightly out-

OF PTERYGO-QUADRATE ARCH IN LACERTILIA. 109

‘ds . At its lower end it is continued into a short pterygodi
ess, pt, which is considerably more slender than the
ipterygoid. Between the base of the epipterygoid and the
te there lies a strong cartilaginous connecting bar. The
ante: end of this bar is of about the thickness of the
- epipterygoid, but on passing backwards it steadily increases in
strength, till on reaching the quadrate it is more than twice the
thickness of the epipterygoid. The quadrate, gu, is bent
considerably backwards, and moderately stout.

Scincide (type, Mabuia sulcata, Peters, fig. 4)—In the

embryo Mabuia the epipterygoid, ep, is present as a straight,
form thick rod of considerable length. At its lower end

Fig 2.

Fic. 3.—The mandibular and pterygo-quadrate cartilages of an embryo (stage Q)
of Eremias capensis, Smith. x 40.
Fic, 4.—Ditto of embryo (stage Q) of Mabuia sulcata, Peters, x 32.

it is continued into a very slender cartilaginous pterygoid
_ process, pt, which is more than half the length of the epipterygoid.
_ The hinder part of the base of the epipterygoid is continued
as a slender cartilaginous bar, which connects it with the
_ quadrate. Both this connecting bar and the pterygoid process,
_ though truly cartilaginous, show evidences of peripheral
degeneration. The quadrate, gu, is well developed and gently
; i curved backwards. It is much flattened, so that the concave
surface looks more outwards than downwards or backwards.
It receives the connecting bar just immediately above the
___ articular surface.
_ ~~ Agamide (type, Agama aculeata, Merr., fig. 5)—It might

110 DR R. BROOM.

readily be expected that Agama, which is the lizard that
appears to be most nearly related to Sphenodon, would show
the quadrato-epipterygoid connection in a more developed
condition than the more specialised lizards, but for some reason
only a trace of the connection is found even in the embryo, and
at no stage is it cartilaginous. At stage Q the epipterygoid, ep,
is present as a very stout and relatively short cartilaginous rod,
thicker above than below. From its base there passes back-
wards a very short cartilaginous spur towards the quadrate,

Fic. 5.—The mandibular and pterygo-quadrate cartilages of an embryo (stage Q)
of Agama aculeata, Merr. x 23.

Fic. 6.—Ditto of an embryo (stage Q) of Chameleon melanocephalus, Gray.
x 33.

which is all that remains in a cartilaginous condition of the
connecting bar. From the tip of the spur the line of the lost
bar can be traced for some distance backwards distinctly as a
cellular structure, which rests on the pterygoid bone, for a short
distance indistinctly, and then on approaching the quadrate
again distinctly as a cellular rod. There is only the merest
vestige of a pterygoid process. At an earlier stage of develop-
ment (stage P) the connecting bar is quite distinct, but it is
not chondrified. . :

The quadrate, gw, is relatively stouter than in the other lizards
examined, and is only very slightly inclined backwards.

Chameleontide (type, Chameleon melanocephalus, Gray, fig.
6)—The Chameleon embryo differs from the other lizards in
having only the vestige of an epipterygoid, ep. What may be
regarded as the base of the epipterygoid, however, is distinct
enough, and from it there pass forwards a short but distinct
pterygoid process, pt, and, towards the quadrate, a cartilaginous

e. | DEVELOPMENT OF PTERYGO-QUADRATE ARCH IN LACERTILIA. 111

- spu r of moderate length, representing the connecting bar.
3 From the tip of the spur a well marked series of cells, which
are continued into the lower end of the quadrate, indicate the
3 ‘position oceupied by the lost portion of the connecting rod.
_ It will thus be seen that the condition of the inner portion
_ of the pterygo-quadrate arch bears considerable resemblance

a to that of Agama.

The quadrate, gv, differs from that of the other forms in being
straight, with an expanded upper end. It is considerably in-
_ ¢lined backwards, and articulates with practically the end of
the lower jaw, mk.

CONCLUSION.

_ The occurrence of a cartilaginous connection between the
quadrate and epipterygoid in Lacertilian embryos of types so
diverse as Zonurus, Eremias and Mabuwia renders it practically
certain that the immediate ancestors of the lizards were
possessed of a fixed quadrate as in Sphenodon; and it thus
becomes manifestly impossible to look upon the degree of fixity
of the quadrate as a character of any great value in classifica-
tion.

The change from the Sphenodon-like ancestral condition to
that of the typical lizard was probably first started by the
loss of the quadrato-jugal, which even in Sphenodon is some-
_ whatrudimentary. When once the quadrate lost its attachment
with the jugal, the posterior limb of the pterygoid would become
_ more developed to compensate for the loss of the external arch ;
and with the increased development of the pterygoid the inner
portion of the quadrate would readily become aborted and then
_ lost, as the pterygoid would afford a better support than the
epipterygoid. |

REFERENCES TO LITERATURE.

(1) Howss, G. B., and Swinnzrton, H. H., “On the Development
_ of the Skeleton of the Tuatara, Sphenodon punctatus,” Trans. Zool.
Soc., Feb. 1901.

(2) Parker, W. K., “On the Structure and Development of the
_ Skull in the Lacertilia,” Phil. Trans., 1879.

(3) Gavper, E.

ON THE DEVELOPMENT AND HOMOLOGY OF THE
MAMMALIAN CEREBELLAR FISSURES! By O.
CHARNOCK BRADLEY, M.B., Professor of Anatomy, Royal
Veterinary College, Edinburgh. (Puates XII-XVI.)

Part I.

VerY few serious attempts have been. made to discover if
there is any regular plan of arrangement of the fissures and
lobes of the mammalian cerebellum. If we leave out of
account those scattered descriptions of the cerebellum of a
single animal, or of one or two animals—such, for instance,
as Ganser’s (1) classic and oft-quoted investigation into the
anatomy of the brain of the mole, Krause’s (2) monograph
on the rabbit, and Miss Arnbick-Christie-Linde’s (3) paper
on the brain of the shrew and bat; not to mention more of a
like nature—we find that the literature on the comparative
anatomy of the cerebellum can only be described as meagre.
Undoubtedly the best work that has been done in the way of
attempting to clear away morphological difficulties is that
which has appeared from the pen of Stroud (4). Another paper
worthy of mention in this connection is that of Kuithan (5),
which appeared almost contemporaneously with Stroud’s. These
two writers stand practically alone, inasmuch as they did not
rest satisfied with an examination of the adult brain, but
demanded to know what embryology had to say. Stroud
traced the development of the cerebellar fissures in the cat
and in man; and Kuithan examined embryos of the sheep
and man.

The latest attempt—as far as is known by the present writer
—which has been made to establish the homology of the lobes
of the cerebellum of mammals appears in the large work by
Flatau and Jacobsohn (6) on the central nervous system. The
value, great though it still remains, of this last piece of work is
impaired by the fact that only adult material was used, and in
many cases apparently second-hand descriptions were accepted.

1 The work, of which the present paper is the outcome, was done by the
writer as a Research Student of the University of Edinburgh.

THE MAMMALIAN CEREBELLAR FISSURES. 113

The ideal method, in a question of this kind, appears to
be a combination of the embryological and the comparative
anatomical. Stroud recognised this, and suggested that it
would be necessary to examine into the intrauterine history of
every mammal—a colossal task, verily. This being beyond the
. compass of the powers of one man, he examined two animals
embryologically, and gave a long list of adult animals which he
stated he had compared with each other. Unfortunately his
description of the adult cerebella, seemingly promised in his
first paper, is not as yet forthcoming.

Kuithan did not attempt the examination of a series of
adult cerebella, but contented himself with the consideration of
the development of the fissures in sheep and in man.

In the case of Stroud, Kuithan, and Flatau and J acobsohn
the investigation was apparently begun with the determination
to find, if possible, homologies to the lobes of the cerebellum of
man. To the mind of the present writer this was a mistake. In
questions of this sort the brain of man should be lost sight of
as far as possible, since it is admitted to be an organ which has
far outdistanced, in its evolution, the brain of the average
mammal. It is only after many (if possible, all) mammals.
have been passed under review that man may be brought in to
complete the list as the highest and most richly endowed.

_ Acting upon the conviction that the brain of man should not
be taken as the standard, but that the simplest cerebella should
form the starting-point, the present investigation was com-
menced with a search for the smoothest and least complicated
mammalian cerebellum. This was discovered—thanks in part
to the paper of Miss Arnback-Christie-Linde—in the shrew and
some of the bats. The shrew’s was therefore taken as the
initial cerebellum; and had it been possible, shrew embryos
would have been examined with a view to noting the time and
order of appearance of the various fissures. Owing to the
difficulty of obtaining a sufficiency of shrews at all periods of
intrauterine life, and because of the comparative ease with
which rabbit embryos of all ages could be obtained, it was
decided to start the embryological part of the investigation
with. the latter; and indeed the rabbit possibly served the
purpose better than the shrew would have done, since the
VOL. XXXVII. (N.S. VOL. XVII.)—JAN. 1903. 8

114 PROFESSOR O. CHARNOCK BRADLEY.

cerebellum of the adult is built on simple lines, and yet there
are parts in it in miniature which attain considerable magnitude
in the larger mammals.

Seeing that the rabbit has a cerebellum so very much more
simple than, say, that of the carnivora or the ungulates, it seemed
well that the development of the fissures in one of the larger
animals should also be watched. For this purpose, because of
the little difficulty in getting material, the pig was chosen. As
it happened, I was able to command material at practically
any stage of development, and therefore the ages of both the
rabbit and the pig embryos were, with one or two exceptions,
absolutely known.

In addition to the examination of the developmental history
of the fissures in two mammals, as many kinds of adult cerebella
as could be obtained have also been compared.

In this paper are stated the results of the investigation,
starting with an account of the appearance of the fissures in
the rabbit. Until the time arrives when it is necessary to
summarise results, the fissures and lobes will be known by
the simplest designations, viz. figures and letters, to the end
that the mind may not be influenced by the use of terms
which have acquired a certain fixed significance.

RABBIT.

20 days embryo, 37 mm. long (fig. 3)—When the entire
brain of the rabbit is examined at this stage, the cerebellum
appears as two fairly prominent lateral projections jutting out
on each side just below the mid-brain. A narrow connecting
band is also seen running transversely between the mid-brain
and the medulla. No fissures are visible to the naked eye;
and on making a sagittal microscopic section in the mesial
plane, the contour is even except at the posterior lower part
of the cerebellar lamina, where a curved hem-like portion is
marked off by a shallow fissure (fig. 3, IV.). This fissure makes
its first appearance about the 18th day (fig. 1). The hem-like
edge of the lamina is continued laterally over the lateral recess
of the ventricle, to become continuous with a similar lip belong-
ing to the medulla (fig. 2). Itis apparently the Rautenlippe (His).

THE MAMMALIAN CEREBELLAR FISSURES. 115

21 days embryo, 42 mm. long (fig. 4)—At this stage the

cerebellum is very similar in appearance, to the naked eye, to

_ that of the preceding day. The middle portion is somewhat
more obvious, but no other visible change has occurred. <A
mesial sagittal section presents an outline which may be roughly
described as triangular, the base of the triangle looking towards
the medulla and pons. The two other sides of the triangle
constitute what it will be convenient to call the anterior and
posterior slopes of the cerebellum. Such a section again shows
the fissure mentioned in the description of the 20 days embryo,
but it is now farther removed from the extreme edge of the
lamina (fig. 4, [V.). There is also a faint indication of another —
fissure at the upper part of the anterior slope (fig. 4, IL). It
may be noted also that the future anterior medullary velum
is better marked, as a result of a slight forward growth of the
anterior part of the cerebellar lamina.

22 days embryo, 50 mm. long (figs. 5,6 and 7)—A distinct

advance has been made in development. The cerebellum is
still very obviously made up of two prominent lateral masses,
connected by a slighter intermediate portion, but the disparity
in volume of these three parts is not so evident (fig. 5). In
addition to a mere growth in size, other important changes
have taken place. On an examination with the naked eye, it
is clear that a portion of each lateral projection is about to be
differentiated from the main bulk of the mass. This is shown
by faint fissures, or rather grooves, slightly indenting the
surface (figs. 5 and 6). Moreover, on sagittal section, the
fissure, faintly foreshadowed in the 21 days embryo at the
upper part of the anterior slope, is unmistakably a definite
entity, and cuts the anterior slope into two almost equal parts
(fig. 7, 11.). The fissure which was the first to appear is still
farther from the edge of the lamina (fig. 7, [V.). Further, there
is the promise of a third fissure, this being indicated at this
stage by a depression on the posterior slope (fig. 7, IIT.).

At this stage there are therefore evidences of three transverse
fissures cutting at least the mesial part of the cerebellum into
four portions; and in addition, indication of a subsequent
complication of the lateral part.

23 days embryo, 50 mm. long (figs. 8, 9 and 10).—There is

116 PROFESSOR 0. CHARNOCK BRADLEY. -

now undoubted evidence of the rudiments of the three parts of
the adult cerebellum. The central portion has increased
considerably in volume, and there are shallow antero-posterior
grooves marking off the future vermis and hemispheres.

The fissure on the posterior slope, which was not more than
hinted at in the 22 days embryo, is now sufficiently deep to
be visible by means of an ordinary pocket lens (fig. 8, IIL). By
the same means two transverse fissures are distinguishable on
the anterior slope (fig. 9). The more superior corresponds to
that already noticed in the previous stage. The lower one of
the two is very shallow, and it is necessary to examine sections
in order to be definitely certain that it is in reality the rudiment
of a fissure.

Sagittal sections show three fissures, with the commencement
of a fourth. The deepest corresponds to the one on the anterior
slope of the 22 days cerebellum (fig, 10, II).

In an embryo of 55 mm. in length, apparently some hours ©
older than the one now under consideration, four fissures can
be distinguished without any difficulty (fig. 11). It is desired
to call especial attention to this stage, for it is believed that
here we have the same number of fissures and lobes in» the
vermis as belong to the simplest form of mammalian cerebellum.
Without applying any special names to these fissures and
lobes, and without anticipating the attempt, which will be
made later, to homologise them with similar features in the
cerebella of other mammals, let it suffice for the present to
designate the fissures as I., IL, III. and IV., and the lobes as
A, B, C, D and E, in each case commencing the enumeration
anteriorly. Of the four fissures we may consider II. to stand
in the first place of morphologic importance. It appears at
an early date in all animals of which we have any embryo-
logical account. | Moreover, it maintains its supremacy
of depth throughout the whole of embryonic life, and on
into the adult state. As has been pointed out by previous
writers, it is the deepest and most constant fissure of the
cerebellum.

In the hemisphere of the 23 days embryo a fissure is growing
inwards towards fissure III. of the vermis, and is consequently
dividing the most lateral part of the hemisphere into two some-

THE MAMMALIAN CEREBELLAR FISSURES, 117

what unequal parts, the more posterior of which projects the
more laterally.

| _—- 24 days embryo, 59 mm. long (fig. 12)—To the naked eye the

_ only change is one of increased size and greater distinctness of
the fissures. In microscopic sections the fissures are obviously
deeper than they were in the preceding stage, and there are
indications of a future fissure in lobe A (fig. 12, ¢).

25 days embryo, 64 mm. long (figs. 13, 14 and 15).—The dis-
tinction of vermis and hemispheres is now very clear, and the
fissures are more definite. Fissure I. is now of considerable
depth and extends completely across the vermis. Fissures II.
and III. have invaded the groove marking vermis from hemi-
sphere. The fissures indenting the lateral part of the hemi-
spheres are deeper and approach fissure III. a little more
closely. Two pairs of additional fissures can be distinguished
in lobe C, these being in the groove between vermis and
hemisphere; one pair on the anterior slope, the other on the
posterior (fig. 13, a, fig. 14, d).

In sections, the fissure whose beginning was seen in lobe A
of the 24 days cerebellum has attained some depth, and another
fissure is forming below it. The former may be called, for the
present, fissure ¢ (fig. 15).

27 days embryo, 67 mm. long (figs. 16, 17 and 18).—All the
fissures are deeper and much more lateral in extent. The out-
standing projection of the hemisphere is now very sharply
marked off from the rest of the hemisphere, and when the
cerebellum is viewed from the front, is becoming - separated
from a smaller eminence which has developed in connection
with the roof of the lateral recess of the ventricle. The upper
and larger projection we shall henceforth speak of as the
parafloceulus, and the lower as the flocculus (fig. 17). These
terms were suggested by Stroud, and are useful as indicating
that the two structures are not equivalent to the flocculus of
man. They arise each in its own particular way. The para-
flocculus is a part of the hemisphere proper. The flocculus, on
the other hand, has developed in the same manner as lobe E,
i.e. in close relationship to the Rautenlippe.

The two lateral fissures on the posterior slope of lobe C have
now run together in the middle line, and constitute a single

118 PROFESSOR 0. CHARNOCK BRADLEY.

transverse fissure cutting the lobe into two parts (fig. 16, a, fig.
18, a).

28 days (?) embryo, 67 mm. long (figs. 19, 20 and 21)—On
the posterior slope the only change is one of depth and distinct-
ness of the fissures, there being no additions. But when the
cerebellum is viewed from the front, it is evident that develop-
ment has here gone on more rapidly. Fissure II. is now in the
form of a crescent, extending almost to the borders of the
hemisphere. The fissures in the lateral parts of lobe C are
also longer and deeper than in the stage described above. An
additional fissure has made its appearance in lobe B. The
paraflocculus and flocculus are separated by a still deeper de-
pression, and the paraflocculus is more sharply separated from
the rest of the hemisphere (fig. 20).

For the sake of subsequent description, we may indicate the
fissure on the posterior slope which divides lobe C into two
parts by the letter a (fig. 19, a, fig. 21,a). That this fissure,
shallow though it is even in the adult rabbit, is of considerable
morphologic importance, is brought out in the section of this.
paper which deals with the various adult cerebella.

At birth.—At the time when the rabbit is born, the cerebellum
is not a replica in miniature of the adult organ, since develop-
ment progresses rapidly for some days after birth.

The cerebellum at birth has its principal fissures of consider-
able depth, and some of its accessory fissures have begun to
form (figs. 22 and 23). The paraflocculus is now completely
surrounded by a fissure, with the exception of its posterior
part, where there is no fissure, but merely a shallow depression.
The flocculus is also completely bounded by a fissure, but as yet
its surface is not sculptured by any lines. Fissure III. fades
away in the groove or depression behind the paraflocculus, as
also does fissure a (fig. 22). Even in the adult the lateral
parts of these fissures are not deep.

2 days after birth—After birth, as has been said, there is a
fairly rapid change for a few days, until the cerebellum comes
to resemble the adult organ.

At the end of the second day the exact connection of the
paraflocculus with the vermis is more precisely indicated.
Fissure III. has grown more laterally, and it is now evident

THE MAMMALIAN CEREBELLAR FISSURES. 119

that the paraflocculus really belongs to lobe D. Lobe E can
hardly be said to extend into the hemisphere at all, fissure IV.
disappearing in the groove between vermis and hemisphere. In
the earlier stages this lobe was continuous, without any fissure of
demarcation with the posterior medullary velum ; but from the
22nd day onwards it projects backwards more and more, and
consequently a limiting fissure is formed.

Adult cerebellum (figs. 24, 25, 26 and 28)—In giving a
description of the adult cerebellum of any animal, it is both
convenient and rational to take fissure II. as the dividing line
between an interior and a posterior portion. In the cerebellum
of the rabbit this fissure lies wholly in the anterior surface, a
surface presenting a concavity into which the mid-brain fits.
Fissure II. oceupies a comparatively high position in the vermis,
but slopes rapidly downwards and outwards across the hemi-
sphere to its border. Its great depth is brought out best by
making a sagittal section of the vermis (fig. 28, II.). Below this
fissure lie some seven folia, the two uppermost of which are
separated from the rest by a fairly deep fissure, which we have
seen makes its appearance about the 23rd day of intrauterine
life, and which has been referred to in the previous paragraphs
as fissure I. This is the deepest fissure in that part of the
vermis which lies anterior to fissure II. When traced outwards
it is found to fail to reach the extreme lateral border of the
hemisphere (fig. 24, 1). Ata distance of two folia below fissure
I. is fissure ¢ (as referred to in the embryonic cerebella), not
quite so deep as the former, but reaching the lateral border.
From the presence of fissure ¢ lobe A is divided into two
portions, which may be called lobule A, below the fissure, and
lobule A, above it. In lobule A, the folia do not extend
farther in a lateral direction than to a line corresponding to
the lateral limits of the vermis, i.e. no hemisphere can be dis-
tinguished in this part of the cerebellum. The question of
whether there is a lingula in the rabbit corresponding exactly
to that of man is one which seems best answered in the nega-
tive. There are certainly no folia adherent to the anterior
medullary velum.

The vermis and hemispheres behind fissure II, are divided
into three lobes (C, D and E), corresponding to those first in-

120 PROFESSOR O, CHARNOCK BRADLEY.

dicated in the 22 days embryo. Lobe C of the vermis usually
carries eight folia, the majority of which are not carried directly
into the hemisphere. The fissures between these folia are for
the most part shallow, but two of them go to a greater depth
than the rest, and are held to be of greater importance. Not only
are they deeper than the others, but they appear at an earlier
period. A reference to the 25 days embryo shows the fore-
runners of these fissures as two pairs of depressions ; one on the
anterior, the other on the posterior slope. In the adult brain
the more anterior of the two occurs between folia 2 and 3
(counting from fissure IT.), and on being traced into the hemi-
sphere is seen to run for some distance parallel to fissure IL.,
into which it ultimately opens. For more immediate purposes
we shall speak of this fissure as fissure 6 (fig. 24, d, fig. 28, 0).
An .offshoot leaves it in the groove between vermis and hemi-
sphere, and curves outwards and backwards to the border of
the hemisphere.

The other deep fissure of lobe C separates folium 6 from
folium 7, and corresponds to the fissure resulting from the union
of the pair of grooves on the posterior slope which first appeared
on the 25th day, and which met in the vermis two days later.
This has already been referred to as fissure a. In the adult it
can be traced to the outermost limits of lobe C. If we recognise
the fissures just mentioned as being of importance, it follows
that lobe C must be looked upon as consisting of three portions
or lobules. These, for the present, will be called lobules C,,
C, and C,, starting the enumeration anteriorly.

The fissure between lobes C and D (fissure ITT.) is of moderate
depth in the middle of the vermis (fig. 28, III.), but becomes
very shallow at its lateral borders. In some specimens, how-
ever, there is not much difficulty in tracing its curved course
outwards and upwards until it is lost in the deep fissure which
separates the paraflocculus from the rest of the hemisphere.
Lobe D is confined to the vermis, but in most specimens there
is a low white ridge connecting it with the paraflocculus. Its
surface is formed by three folia (sometimes a shallow fissure
divides the lowest folium into two). Of the two fissures
between these folia the lower is slightly the deeper, and the
lower folium extends rather farther towards the hemisphere

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THE MAMMALIAN CEREBELLAR FISSURES. 121

than the other two. These facts are mentioned because of the

belief that lobe D of the rabbit corresponds to two lobules in
more complicated cerebella.

_ Lobe E is entirely confined to the inferior aspect of the
cerebellum, and, like lobe D, has no direct continuation into
the hemisphere.

_ The paraflocculus projects markedly from the lateral part

of the hemisphere, from which it is separated by a deep

fissure in front and above, and by a depression behind. It
is entirely enclosed in a special fossa formed by the temporal
bone (lobulus petrosus). As has been seen in tracing its
development, it is really a piece of the hemisphere which has
been cut off from the rest. Its developmental connection with
lobe D is a point upon which it is desired to lay emphasis.

The flocculus consists of two or three folia, seen best when
the cerebellum is viewed from the front, and lying anterior
to the paraflocculus (fig. 25). It is in contact with the lateral
extremity of lobe B, from which it is separated by a fissure
which contains the middle cerebellar peduncle (fig. 24).

Lepus timidus (tig. 27)—The differences between the cere-
bellum of the rabbit and that of the hare are not perhaps
very great, but they seem sufficiently important to merit
mention. Lobes A, B and C are practically identical with those
of the rabbit. Lobe C has again eight folia in the vermis, and

a fissure, a, deeper than the rest, separates folia 6 and 7. This

fissure is much more definite in oonamrepeets of the hare than
it is in the rabbit.

The most important differences exist in lobe D. Here the
number of folia is at least four, as against three in the rabbit;
and the uppermost of the four is more definitely joined to the
paraflocculus by a ridge which is slightly foliated along its
upper border as it approaches the paraflocculus. This fact is
mentioned as being the ground upon which the statement, that
in the adult rabbit lobe D is connected with the paraflocculus,
is based. In many specimens of the rabbit's cerebellum the
adult connection is obscure; therefore the evidence afforded
by the brain of the hare is welcome,

Before passing to the consideration of the development of

* the much more complicated cerebellum of the pig, it is perhaps

122 PROFESSOR O. CHARNOCK BRADLEY.

well to describe those adult cerebella which are built on the-
same or similar lines as obtain in the rabbit.

Sorex vulgaris (fig. 29).—As previously stated, apparently
the simplest form of mammalian cerebellum is found in the
shrew and some of the bats. An examination of sagittal
sections of the shrew’s cerebellum shows that the vermis is.
divided into fine lobes by four fissures, 7c. that the numerical
condition as found in the brain of a rabbit embryo of about.
24 days is maintained into adult life. Fissure I. is of moderate
depth, but does not extend much, if at all, beyond the vermis.
Fissure II., on the other hand, is very deep, and passes far out.
into the hemisphere. Its importance as a morphologic entity
probably stands out more plainly in the shrew, and some few
animals with a similar simple cerebellum, than it does in many
of those in which the fissures are more numerous.

Fissure III. is the shallowest of the fissures of the vermis,
and does not invade the hemisphere, or at any rate only slightly.
There is a fissure in the hemisphere occupying a corresponding
position, but microscopic sections show that there is no union
of the two. Fissure IV. very early disappears in a series of
sections, There is a projection, from the lateral part of the
hemisphere, enclosed in a cell in the temporal bone, and
doubtless corresponding to the paraflocculus of the rabbit. It
seems very doubtful if a floeculus proper is developed.

Erinaceus Europeus (figs. 30, 31, 32, 33 and 34).—The
hedgehog has a cerebellum which, in degree of complexity, may
be considered to stand. between that of the shrew and that of
the rabbit. The vermis is divided into five lobes by four
fissures, of which the second (fissure II.) is by far the deepest.
This is visible in the’ vermis when the cerebellum is examined
from above, but it leaves the dorsal to gain the anterior surface
in the shallow groove which marks vermis from hemisphere.
In the hemisphere it slopes rapidly downwards and outwards,
in much the same manner as in the rabbit. Fissure I. is second
in point of depth. Unlike the corresponding fissure in the
rabbit, it reaches the borders of the hemispheres, Fissures.
III. and IV. are of moderate depth, and run into one another
at the lateral boundary of the vermis.

Lobe A is, as a rule, beset by three folia, and, unlike the-

Se ae

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THE MAMMALIAN CEREBELLAR FISSURES. 123

corresponding lobe in the rabbit, is not divided by a fissure, ¢.
Lobe B has never more than two folia, so far as can be

gathered from an examination of some ten brains. Lobe C

has five folia in the vermis, the four anterior of which are
separated from the fifth by a fissure which corresponds to @ in
the brain of the rabbit, and which is continued into the
hemisphere in a like manner. Lobe C, anterior to fissure a,
becomes much expanded in the hemisphere, and its folia are
increased in number. The folium behind fissure a retains its
single character after its prolongation into the hemisphere
(lobule C,). Lobes D and E have each two folia, and are
confined to the vermis.

_ The paraflocculus is fairly well marked, but does not produce
the projection (lobulus petrosus) which is so prominent in the
rabbit. The flocculus is rather smaller in the hedgehog than
in the rabbit, but has approximately the same position and
shape as in the latter animal. Sagittal sections show very
clearly the close relationship of this lobule with the posterior
medullary velum. As successive sections are examined in a
direction away from the vermis, the velum is seen to become
thickened by grey matter, which is directly continuous with
the grey matter of the flocculus.

Talpa Europea (figs. 35, 36 and 37).—In the vermis of the
cerebellum of the mole, the four fundamental fissures are easily
distinguished. Fissure I. is relatively a slightly greater depth
than in either the rabbit or the shrew. It is, as usual, limited
to the anterior surface, and runs almost vertically downwards
in the line of boundary between vermis and hemisphere.
Fissure II. is of very considerable depth. Its course is very
sinuous, beginning on the anterior surface of the vermis, then
taking a sharp bend backwards over the anterior superior
border of the cerebellum to gain the dorsal surface, where it
again turns sharply forwards and outwards to once more become
included in the anterior surface, down which. it runs almost
vertically. Fissure III. is more distinct than in the shrew.
Fissure IV. is of about the same depth as in Sorex.

Lobe A is almost entirely in the vermis, though it expands
a little in the lower part of the anterior surface. Its surface
possesses two fissures, the lower of which is more pronounced,

124 PROFESSOR 0. CHARNOCK BRADLEY.

and may possibly be comparable to fissure ¢ of the rabbit; a
fissure not represented in the shrew. Lobe B is constricted in
the vermis, where it is constituted by a single folium; but,
owing to the erratic course taken by fissure IL, it expands
considerably in the hemisphere. That part of lobe C which
is included in the vermis is comparatively extensive. This
lobe is constricted at the junction of vermis and hemisphere,
to become again extensive in the hemisphere itself. There
are a few shallow fissures in the vermis, but one of them is of
slightly greater depth than the rest, and corresponds to fissure a.
Lobule C, consists of a narrow folium in the vermis, but
expands in the hemisphere (fig. 35). This is a point of some
moment, because in the more complicated cerebella, to be
hereafter described, the expansion of this particular lobule in
the hemisphere is a prominent feature. Lobes D and E are
simple and call for no remark, except that a very thin and
narrow band runs outwards and forwards from D, but is
entirely hidden by the bulk of the hemisphere. This band
extends as far forwards as the base of the paraflocculus.

The paraflocculus is in the form of a rounded lobule, with
fissured surface, connected with the hemisphere by a narrow
neck, and enclosed in a fossa of the temporal bone. No flocculus
can be made out with certainty.

Mus decumanus (figs. 38, 39, 40 and 41)—The cerebellum
of the rat is decidedly more complicated than that. organ in the
mole or hedgehog, and approaches more nearly that of the rabbit.
Fissures I. and II. resemble those of the rabbit, except that I.
always reaches the margin of the hemisphere, and the central
part of II. is visible of the dorsal surface. Fissures III. and IV.
are also very similar to those of the rabbit’s cerebellum.

Lobe A is divided into two parts by a fissure, ¢, which is
almost as deep as I. The upper part of this lobe (lobule A,)
has two folia; the lower part (lobule A,) a variable number,
separated by shallow fissures (fig. 41). Lobe B has two folia,
and resembles the like lobe in the rabbit both in position and
size. In lobe C there is a deep fissure, a, cutting the vermis to
almost the same depth as fissure III., and separating a single
folium, which is continued into the hemisphere. The rest of
lobe C, which is contained in the vermis, has about three folia,

THE MAMMALIAN CEREBELLAR FISSURES. 125

of which the most anterior is the largest. A definite fissure, J,
cannot be made out. The hemisphere part of lobe C, anterior

to fissure a, is of considerable size. Lobes D and E are confined

to the vermis, the former having three folia, the latter two.

The paraflocculus projects from the hemisphere by a narrow
neck, and is received into a fossa in the temporal bone, the
investment of bone being less close than in the rabbit. There
is a small, simple flocculus lying anterior to the paraflocculus,
and touching the lateral borders of lobes A and B.

In the mouse (Mus musculus) the cerebellum very closely
resembles that of the rat. The paraflocculus has possibly a
slightly narrower neck and is more closely invested by bone.

Arvicola amphibius (figs. 42, 43 and 44)—The water-vole
has a cerebellum which differs from that of the brown rat in
minor points only. Its fissures are the same in number. As a
rule, fissure I. does not quite reach the border of the hemisphere.
Lobe A is divided by a fairly deep fissure, c. Lobule A, has two
folia, lobule A, only one. ‘Lobe B is narrow (as in the rat),
and possesses two folia in the vermis. The vermis portion of
lobe C has six folia, fissure a separating the sixth from the rest.
The sixth folium (constituting the central part of lobule C,) is
continued into the hemisphere without either increase in size or
accession of fissures. There is possibly a fissure, b, placed between
the 2nd and 3rd folia, and continued outwards and forwards into

the anterior surface of the hemisphere.

_ Lobes D and E are limited to the vermis, D having two
folia, E only one. The parafloceulus and flocculus are almost
identical with those in the rat. .

The cerebellum of the field-vole (Arvicola agrestis, fig. 45)
only differs from that of the water-vole inasmuch as its folia are
fewer in number.

Pteropus poliocephalus (figs. 46, 47,48 and 49).—A sagittal sec-
tion through the middle of the vermis of vhis large bat discloses
an arrangement of lobes not very unlike that of the hedgehog.
The number of lobes and fissures is the same, but the folia are
somewhat more numerous. Fissure I. is rather shallow, but
fissure II. is of great depth; of fissures III. and IV. there is
nothing remarkable to note. Lobe A is small and carries about
three folia. There is apparently no fissure c. Lobe B, on the

126 PROFESSOR 0. CHARNOCK BRADLEY.

other hand, is large, and is provided with five or six folia. There
are seven folia in the vermis in lobe C, the seventh of which is
separated from those anterior to it by an unmistakable fissure
a. This single folium of the vermis is connected with two folia
inthe hemisphere. In Talpa, lobule C, increased in size in the
hemisphere, but did not acquire any intrinsic fissures. In
Pteropus it also expands, and in addition is sculptured by a
fissure. It seems good to call attention to this point, in the
light of other facts presently to be set forth. Lobes D and E
belong exclusively to the vermis; the former has three folia,
the latter two.

A noteworthy development appears in the parafloceulus. It
consists of two parts, an upper and a lower. In the cerebella
to be described in the following pages, the morphologic import-
ance of this feature of the paraflocculus will become evident.
The lower portion of the paraflocculus of Pteropus consists of a
lobulus petrosus; ze. it projects into a bony fossa and has a
narrow neck. Both portions of the paraflocculus are foliated
(figs. 46 and 47). The flocculus is small, and divided into two
by an almost vertical fissure, only seen when the cerebellum is
viewed from the side.

It is interesting to notice the great difference in the cere-
bellum of the Megachiroptera as shown in Pteropus, and
that of the Microchiroptera as exemplified in Vesperugo
pipestrellus, described and figured by Miss Arnbiich-Christie-
Linde (3). Vesperugo has a cerebellum not more complex than
that of the shrew, whereas the cerebellum of Pteropus is as
complex as that of the rabbit, or possibly more so.

Sciurus vulgaris (figs. 50, 51, 52 and 53).—The squirrel
offers a most instructive degree of complexity in the fissures
and lobes of its cerebellum, inasmuch as it exhibits a condition
intermediate between the simpler forms, which have already
been described, and those of a more complicated nature, still to
be considered. For this reason the squirrel’s cerebellum is
peculiarly serviceable to anyone desiring to establish homologies
in the lobes and fissures of mammals in general.

Fissure I. in the squirrel, as in the rabbit, stands second in
point of depth. Also, as in the rabbit, it fails to reach the
margin of the hemisphere. Fissure II. is far and away the

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THE MAMMALIAN CEREBELLAR FISSURES, 127

deepest of all the fissures. It is visible in the vermis, on the
dorsal surface; but turning forwards abruptly, it runs down the
anterior surface of the hemisphere, with only a slight degree of
obliquity. Fissure ITI. is of considerable depth, and on reaching
the border of the vermis, turns at almost a right angle, and
runs nearly vertically downwards for some distance. Then,
eurving outwards and afterwards forwards, it is traceable into
the deep fissure separating the paraflocculus from the hemi-
sphere (figs. 51 and 52, III.). Fissure IV. resembles the same
fissure in the rabbit, and offers no noteworthy feature.

The greatest interest centres itself in the lobes. Lobe A is
of considerable size, consists of five folia, and is indented by a
fissure, c, between the 2nd and 3rd folia. Another fissure, of a
depth almost equal to that of ¢, occurs at a distance of two folia
below the latter. Lobe B consists of three or four folia and is
not very noteworthy. Lobe C has five folia in the vermis. The
anterior four expand in the hemisphere, in the customary
manner, and are separated from the fifth by a fissure,a. The
fifth folium, instead of remaining as a single folium when traced
into the hemisphere, as in the rabbit, suddenly expands and
forms a not inconsiderable lobule, clearly differentiated from the
rest of lobe C by a continuation of fissure a (fig. 52). Lobe D
is relatively large and carries six folia. It is divided into two
approximately equal parts by a fissure of a depth only slightly,
if at all, inferior to that of fissure III. We shall refer to this
latest fissure as d in future descriptions, as its value as a
division between parts of the vermis is unquestionable (figs.
51, 52 and 53, d).. That part of lobe D which lies above fissure
a (and which we may call lobule D,) consists of two folia, which
becoming one, curves round the inferior border of lobule C,, and
losing its grey cortex, gives place to a white ridge passing
directly to the upper part of the paraflocculus. That part of
lobe D inferior to fissure d (known in the succeeding descriptions
as lobule D,) is not continued into the hemisphere. Lobe E is
comparatively small, and consists of only one definite folium.

The paraflocculus is large when compared with the similar
lobule of the cerebella already described, and presents the
appearance of a rounded foliated band which has been doubled
upon itself and placed with its long axis approximately in the

128 PROFESSOR O. CHARNOCK BRADLEY.

direction of the long axis of the head. The bend is in front
(figs. 51 and 52). The flocculus is small and compressed. It
lies below the paraflocculus, and can only bp seen from the side
or front of the cerebellum.

The points in the foregoing description to which it is desired
to draw especial attention are as follows :—(1) The increasing
complexity of lobe A as compared with the same lobe of all the
other animals so far discussed. (2) The considerable expansion
in the hemisphere of lobule C,. (3) The division of lobe D
into two parts by the fissure d, and the lateral continuation of
the upper part (lobule D,) of this lobe. (4) The arrangement
of the paraflocculus in the form of two parallel portions, con-
tinuous with each other in front, and the connection of lobule
D, with the upper portion of the paraflocculus.

The cerebella which remain to be described are all built on
much more complicated lines than are those which have been
passed under view in the foregoing sections. This being so the
examination of the development of the fissures in an animal
possessing a richly fissured and foliated cerebellum in adult life
will greatly aid in the task of recognising homologies. There-
fore pig embryos will be examined, with a view to noting the
time and order of appearance of the various fissures.

(To be continued.)

REFERENCES.

(1) Gansgr, S., “ Vergleichend-anatomische Studien iiber das

Gehirn des Maulwurfs,” Morpholog. Jahrbuch., Bd. 7, 1882, p. 591.

(2) Krausg, Die Anatomie des Kaninchens, 1884,

(3) ArnBick- CurisT1E-LinpE, Augusta, “Zur Anatomie des
Gehirnes niederer Saugetiere,” Anat. Ang., Bd. xviii., 1900, p. 8.

(4) Srroup, B. B., ‘‘The Mammalian Cerebellum,” Journ, Comp.
Neurology, vol. *2 1895, p. 71.

Ibid., ‘A Preliminary Account of the Comparative Anatomy of the
Cerebellum,” Proc. Assoc. American Anatomists, May 1897.

Tbid., “‘ Morphology of the Ape Cerebellum,” Proc. Assoc. American
Anatomists, Dec. 1897.

(5) Kurruan, W., “ Die Entwicklung des Kleinhirns bei Sauge-
tieren,” S, B. Ges. Morph. Physiol., Miinchen, 1894, and Miinchener
Medicinische Abhandlungen, vii. Reihe, 6 Heft, 1895.

(6) Fuarau, E., und Jacopsoagn, L., ‘‘ Handbuch der Anatomie und
vergleichenden Anatomie des Centralnervensystems der Siugetiere,”
Berlin, 1899.

Seneittate

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(PLare XII.

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. and Physiology, Jan. 1903.) [PLATE XV.

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Professor O. CHARNOCK BRADLEY on the Development and
Homology of the Mammalian Cerebellar Fissures.

Journ. of Anat. and Physiology, Jan. 1903.) {(PLrare XVI.

[ -).-Parajloce clus

sa Parafloceul

Fic. 45-

Professor O. CHARNOCK BRADLEY on the Development and
Homology of the Mammalian Cerebellar Fissures.

THE MAMMALIAN CEREBELLAR FISSURES. 129

PLATES XIL-XVL
EXPLANATION OF FIGURES,

-

_In s the figures the same letters and figures are used for corre-
3 g fissures or lobes.. The application of the letters and figures
= ss ined in the text.

a ‘p.m.v. (in figs, 1 and 3) = posterior medullary velum.

4@.m.v, (in figs. 4 and 7) = anterior medullary velum.

_ch.pl. (in figs. 1, 2 and 3) = choroid plexus.

All the sections ‘(with the exception of that shown in fig. 2) are ih
“the median plane and sagittal in direction.

ve 1. Rabbit embryo, 18 days, 21 mm. Mesial sagittal section

; through the cerebellar lamina.

| Mig 2. Same embryo. Sagittal section where the cerebellar lamina
and the medulla are joining. Jat. rec. =lateral recess.

“Fig. 3. Rabbit embryo, 20 days, 37 mm. Mesial sagittal section

= through the cerebellar lamina.

_ Fig. 4. Rabbit embryo, 21 days, 42 mm. Mesial sagittal section.

Fig. 5. pa 22 days,50 mm. Posterior view. x 2.
4 or 6. ig 22 days, 50 mm. Left lateral view. x 2.
Fig. 7. RS 22 days, 50 mm. Mesial sagittal section.
Fig. 8. i 23 days, 50 mm. Posterior view. x 2.
> Fig; 9. Pe 23 days,50 mm. Anterior view. x 2.
Fig. 10. “ 23 days, 50 mm. Mesial sagittal section.
er Fig. 11. a 55 mm. Mesial sagittal section.
_ Fig. 12. na 24 days, 59mm. Mesial sagittal section.
Fig. 13. in 25 days, 64mm. Posterior view x 2.
_ Fig. 14. < 25 days, 64mm. Anterior view. x 2,
Fig. 15. “ 25 days, 64 mm. Mesial sagittal section.
Fig. 16. a 27 days, 67 mm. Posterior view. x 2.
Pig. 17. ‘5 27 days, 67 mm. Anterior view. x 2.
Fig. 18. = 27 days, 67 mm. Mesial sagittal section.
Fig, 19. ‘ 28 days (?) 67 mm. Posterior view. x 2.
o Pig. 20. - 28 days (?)67 mm. Anterior view. x 2.
| Fig. 21. 28 days (?)67 mm. Mesial sagittal section.
oe Big. 22. Rabbit, 30 hours after birth, Posterior view. x 2.
_ Fig. 23. ,, 30 hours after birth. Anterior view. x 2.
' Fig. 24. +, adult. Anterior surface. x 2.
og. 25. mn Left lateral surface. x 2.
ae # ‘ om Posterior surface. x 2.
Fig. 27. Lepus timidus. Posterior view. x 2.
. Rabbit, adult. Mesial sagittal section,
. Sorex vulgaris. Mesial sagittal section.
. Erinaceus Europeus. Mesial sagittal section.
; oe = Anterior surface. x 2.
© Fig. 32. e Left lateral view. x 2.

VOL. XXXVIL (N.S. VOL. XVII.)—JAN, 1903, 9

THE MAMMALIAN CEREBELLAR FISSURES,

. Erinaceus Europzeus. Superior view. x 2.

Posterior view. x 2.

” ’
. Talpa Europzea. Superior-posterior view. x 2.

ve Anterior surface. x 2.
Mesial sagittal section.

”
. Mus decumanus. Posterior view. x 2.

pes Superior view. x 2.
is Anterior surface. x 2
Mesial sagittal section.

2. Arvicola amphibius. Superior surface. x 2.

Anterior surface. x 2,

” 39
Mesial sagittal section.

” bf
. Arvicola agrestis. Mesial sagittal section.
. Pteropus poliocephalus. Superior view. x 2.

i Posterior view. x 2.
Anterior surface. x 2.
Mesial sagittal section.

” 9

+P ”
. Sciurus vulgaris. Anterior surface. x 2.

* Superior view. x 2.
i Posterior view. x 2.
Mesial sagittal section.

ee

THE EVOLUTION OF THE TEETH IN THE MAMMALIA.

By H. W. Marert Tims, B.A. (Camb.), M.D., M.Ch. (Edin.),
King’s College, Cambridge.

_ OF the many problems in Comparative Odontology, one of the
most interesting morphologically and most important phylo-

genetically is that dealing with the origin of the complex

. -erowns of the mammalian cheek-teeth, and their evolution

from a primitive haplodont type. The importance of this
problem lies in the fact that the teeth, composed of the hardest

3 tissues in the body, enamel and dentine,. have furnished the

sole remains of many an ancestral form, at least so far as
paleontological evidence exists at the present time. This

. being so, the gradual evolution of the dental patterns may not

unreasonably be expected to throw light upon the origin and
inter-relationships of the mammalia. The latter question was

one of the subjects for general discussion at the Fourth Inter-

national Congress of Zoology held in Cambridge in 1899.
By almost unanimous consent the ancestors of the mammalia

a are to be looked for among the reptilia, though various writers

have furnished what might be considered as arguments in
favour of a direct amphibian descent.

In 1879 Huxley, in discussing the characters of the
mammalian pelvis and the homologies of the abdominal muscles
of the monotremata, says (12), “It seems to me that in such
a pelvis as that of the Salamandra we have an adequate

4 representation of the type from which all the different modi-
fications which we find in the higher vertebrata may have
_ taken their origin.” He also pointed out that the pectoral

; ; : ‘girdle of the monotremes is “as much amphibian as it is
___ sauropsidan ; the carpus and tarsus of all the Sauropsida, except

the Chelonia, are modified away from the Urodele type, while

those of the mammal are directly reducible to it,”

Professor Marsh (20) also points out that the dicondylian
skull is not present in any true reptile, “although the contrary
has been asserted. The nearest approach appears to be where

132 DR H. W. MARETT TIMS.

there is a single bifid condyle, cordate in shape, with the two
lobes meeting below, as in some reptiles and a few birds, but
not separate as in mammals and amphibians.” Moreover,
Hubrecht has shown that the mammalian ovum approximates
more nearly to the amphibian type than to the reptilian.
Dr Gadow, on the contrary, considers it beyond reasonable
question that the mammals have sprung from some reptilian
stock (“the attempts to derive them from amphibia, without the
intervention of reptiles, are as gratuitous as they have proved
futile”) (6). . |

That the mammals’ were primitively derived from verte-
brates having a general covering of some form of dermal
appendage, possibly similar to that of existing elasmobranchs,
is, I think, certain. That such appendages partook of the
nature of teeth is evidenced by their vaso-dentinal structure
in many fossil forms. The earliest adult lung-breathing
vertebrates known are the Stegocephala of the Lower Carbon-
iferous of Western Europe. These, as Smith Woodward points
out, “ exhibit many resemblances to the paleeozoic Crossopterygian
fishes in the dentition and the outward aspect of the skull”
(33). Many of the Crossopterygii were more or less completely
covered with dermal appendages, and a “ventral armour of
small overlapping scales” is almost universal among them,
some being “even armoured dorsally.”

In the mammalia the presence of hair or fur over the surface
of the body points back to the primitive condition, for, as
Huxley says (11), “It appears to me indubitable that the
teeth and the hairs are homologous organs.”

The balance of evidence therefore tends to show that the
mammals were primitively derived from a fish-like precursor,
having a general covering of tooth-like appendages. In the
course of evolution these underwent various modifications,
those retaining the tooth-like characters becoming more re-
stricted in their area of distribution. In existing fishes the
latter are by no means limited to the jaws, being present in
some of the Teleosteans on all the bones of the mouth, as well
as those of the hyoidean and branchial arches. Ascending the
vertebrate series, they become yet more restricted, being found
only on the maxille, pre-maxille, mandible, and on the roof of

e
t

i

7

:

7

7
’
4
a
;

THE EVOLUTION OF THE TEETH IN THE MAMMALIA, 133

the mouth (the vomerine teeth of the amphibia), these last
tending to disappear in the fossil Theriodontia, and are wanting
in most existing reptiles and mammals.

With this gradual limitation in area of distribution, there is
4 specialisation of the teeth themselves, which at the same
time acquire a greater degree of fixity. That the greater
specialisation is confined to those animals in the direct line of
vertebrate ancestry is not the case, the teeth of the Laby-
rinthodonta being vastly more complex than those of any
mammal. In fishes the teeth are found upon the inner sides
as well as upon the free edge of the jaws, and as they become
worn down fresh ones take their place, giving rise to a
polyphodont condition. Among the reptilia they are usually
pleurodont or acrodont in their mode of attachment, though
in the crocodilia as in the mammalia the thecodont condition
obtains.

The type of the primitive tooth was the haplodont, or simple
cone; and the object of the present paper is to endeavour to
trace the evolution of the complex crowns of the mammalian

_ cheek-teeth from such a pattern.

Complex teeth are by no means limited to the mammalia,
being found in the fishes, amphibia and reptiles. In the
earliest sharks complex teeth are present, which have arisen by
the fusion of originally separate cusps. In the Cochliodontide
of the Upper Paleozoic there is believed to have taken place
not only a fusion of the teeth of the same series, but also of
those of successional series. Other methods of tooth complica-
tion have probably been in operation in former geological times.
‘The Notidanide of the Jurassic, Cretaceous and Pliocene periods
show a progressive addition in the number of cusps, in such a
manner as to render the concrescence hypothesis highly im-
probable. Again, in existing fishes, Semon (25) has shown that
a fusion of individual cusps takes place in the teeth of Ceratodus ;
and Professor Graham Kerr tells me that he has been able to
verify this statement, though he has not been able to find any
traces of concrescence in Lepidosiren. Again, in the reptilia,
though a homodont dentition of a haplodont type is the rule,
nevertheless in the existing Sphenodon and in many of the
Permian and Triassic forms, a heterodont condition is to be

134 DR H. W. MARETT TIMS,

found. Harrison has shown (10) that in the development of the
teeth in Sphenodon there are distinct evidences of concrescence.
Among recent mammals, while complex cheek-teeth are almost
universal, the haplodont exists in such forms as Delphinus.

Various theories have been advanced from time to time to
account for the evolution of the mammalian molars from this
simple pattern. Most of these are too well known to need
description ; reference will therefore only be made to them for
the purposes of criticism.

The first attempt at a systematic description of the teeth of
mammals was made by Cuvier (3) in 1825. Subsequently Owen
took up the study and added considerably to our knowledge.
As far as I have been able to ascertain, the first writer to
advance any theory in explanation of the molar evolution was
‘Gervais (8) in 1854. His theory was practically that now
known as the Concrescence theory, which supposes the fusion
of a number of reptilian cones, the apices of which would give
rise to the various cusps of the mammalian molars. Other
~ investigators followed in the same lines, notably Gaudry (7) in
1878, and Dybowski (4) in 1889. Though these writers suggest
this theory as applicable to the molars of mammals in general,
they were more particularly concerned with those of the
. ungulata and. proboscidea. Among more recent writers Rése
claims to have seen cusps in the process of fusion in the teeth
of the chameleon (23), and Kiikenthal in the rudimentary molars
of the walrus (14). The latter author also regards as an
argument in favour of this view the fact that in the cetacea
the teeth disintegrate by a splitting down between the cusps, a
reverse process to that of evolution. He also cites the multi-
tuberculata as having teeth probably formed by the fusion of
teeth, not only of the same dentition, but of those of different
dentitions, thus accounting for the transverse rows of three cusps
so frequently found in these mesozoic forms, while the molars
of the higher mammals, with their transverse rows of two cusps,
he would regard as representing a fusion of the milk and per-
manent dentitions. As far as I am aware, this theory has not

been adopted to account for the complexity of the premolars, ~~

except by inference they may be held to represent an antero-
posterior fusion of cusps of a single dentition.

THE EVOLUTION OF THE TEETH IN THE MAMMALIA. 135

M. F. Woodward (31) adversely criticises these conclusions
from an embryological standpoint. He says this view “will
not hold for all mammals, for if the lingual continuation of the
dental lamina represents-the anlage of the replacing teeth, that
structure can be seen in some mammals to remain quite distinct
from the adult molar, and in the end to gradually disintegrate
as the growth energy is abstracted from it by the larger and
earlier developed tooth.” Anyone who has had practical ex-
perience in the investigation of tooth-genesis will readily admit
the truth of Woodward’s statement.

In earlier papers I was unable to admit the validity of the
conerescence hypothesis ; more recently, however, I have been
induced to accept it, but not to the full extent advocated by
Kiikenthal and others. An antero-posterior fusion of the teeth
of the same dentition appears to me now to be the only solution
of the difficulty in accounting for the duplex condition of the
true molars of the greater number of mammals and of the
complex cheek-teeth of the rodents and fossil multituberculata.
The repetition, so to say, of the development of the anterior and
posterior halves of the rodent molars seems to me to render this
highly probable, though I have not yet seen any actual fusion of
enamel germs. It may quite well be that this early stage may
have become slurred over in the recapitulatory history, until it
is entirely lost at the present day. Possibly the same may be
true of the ungulates and proboscidians.

Kiikenthal’s adaptation of this hypothesis to the molars of
the higher mammals, in so far as it relates to the fusion of
teeth of different dentitions, is, I think, untenable. The
quotation from Woodward just given sufficiently disposes of
the lingual downgrowths of the dental lamina, and the same
remark applies with equal force to the labial downgrowths,
where these are distinct and do not take part in the formation
of an external cingulum, many instances of which are known
to occur. In the concentric epithelial bodies of Cavia, Canis,
Gymnura and Ornithorynchus we have, I believe, the last
traces of a vanishing dentition which must have preceded the
cheek-teeth on account of their labial position. These bodies
remain quite distinct from the teeth themselves, and show no
tendency to become fused.

136 DR H. W. MARETT TIMS.

Little or no weight attaches to the evidence derived from the
disintegration process of the cetacean molars. That there is
nothing inherently improbable in the Concrescence theory is
true; indeed, the shortening of the jaws which occurs so
generally throughout the mammalia might easily account for
antero-posterior fusion, though it is difficult to conceive of any
forces which would produce lateral fusion of successive denti-
tion.

That fusion does take place in the teeth of other vertebrates
has already been shown. Nor must the evidence furnished by
Ameghino be omitted, the numerical relationships between the
cusps of the mammalian teeth and the number of individual
teeth being very striking (1).

From a consideration of the facts available, I am inclined to
accept the Concrescence theory in so far as it relates to an
antero-posterior fusion of the cusps in the true molar region
only, but I am at present unable to find sufficient evidence of
any lateral fusion in these or other forms.

The Tritubercular theory was advanced by Cope in 1873 (2).
It has since become the most widely known theory of
mammalian tooth-genesis, owing to the numerous publications
on the subject by H. F. Osborn, Scott, Earle, Allen, Wortman,
and other American morphologists. It has also met with wide
acceptance on the European continent, finding adherents in
v. Zittel, Rutimeyer and Schlosser. Rose, Leche and Taeker
have dealt with the subject from the embryological standpoint,
and would appear to have accepted it, though somewhat more
reservedly. In this country the theory has not met with such
general acceptance. Sir William Flower and Lydekker appear
to have done so; but with the majority of English writers,
including Forsyth-Major, Smith Woodward, M. F. Woodward
and E. S. Goodrich, trituberculism seems to have found but
little favour.

The discussion as to the tenability of this Sepotinal can be
approached from two points of view, the embryological and
paleontological.

The tooth-genesis has been worked out in individual members
of quite a number of mammalian orders, attention being paid to
the order of cusp development. Rése has dealt with the

THE EVOLUTION OF THE TEETH IN THE MAMMALIA. 137

imates (21) and marsupials (22), Taeker with the ungulates
(26), and I have investigated the tooth-genesis in the carni-
vores (27), rodents (28), and recently in man, while M. F.
_ Woodward has examined the insectivores (32). The results
_ exhibit a remarkable uniformity. With the exception of two
a _insectivores, Centetes and Ericulus, in no single instance does the
a develop first, as it should do if ontogeny in any way \
= _ recapitulates phylogeny ; with these two exceptions, the paracone
and protoconid, in other words the antero-external cone, being
always the the first to appear. This remarkable uniformity cannot
be a mere coincidence, and can, I think, only lead to one con-
q Beasicn, namely, that the paracone and protoconid are homolo-
q gous cusps, and represent the primitive reptilian cone, as first
_ suggested by Roése (21); as far as I am able to understand
_ Winge (30), this is the conclusion at which he also has
arrived. As to the exceptional insectivores above alluded to,
_ Centetes and Ericulus, the protocone of the molars is said to
_ develop first. This cusp is so named from a tritubercular
_ standpoint, but it appears open to doubt whether it is in
E semoslity the homologue of the protocone of most other mammals.
__ If the teeth of these two forms be examined, it will be seen that
the so-called paracone and metacone are placed externally to the
f protocone, and would seem to partake of the nature of external
- cingulum cusps, such as one finds highly developed in Otocyon
_ among the carnivores, and Talpa and Chrysochloris among the
_ insectivores. Of the three last mentioned animals, in Talpa
_ alone has the tooth-genesis been worked out, and in it the
_ paracone is the first to appear. A comparison of the molars
_ of Talpa and Centetes leads me to believe that the so-called pro-
_ tocone of the latter is really the homologue of the paracone of
_ the former, a conclusion entirely in agreement with Woodward,
zg and a modification of the view put forward by Mivart in 1868
_ (15), but a conclusion not hitherto usually accepted. Should
this interpretation prove to be correct, then all the insectivore
_ molars fall into line with those of other mammals as yet
embryologically investigated.
It has been necessary to dwell upon this point at some length
_ since Prof. Osborn, in a memorial paper to the late Prof. Cope,
entitled “ Trituberculy ” (17), finds in Woodward's work on the

Pr

138 DR H. W. MARETT TIMS.

tooth-genesis in the insectivores further evidence in favour of
this theory. Professor Osborn quotes from the first part of
Woodward’s work, dealing with the order of cusp development
of Centetes and Chrysochloris, in which the so-called protocone
is said to arise first, but he omits to mention that Woodward is
later on concerned at some length with the discussion as to the
homology of the protocone in these forms with the paracone of
other insectivora, and in which he says (p. 588)—*“ With regard
to the tritubercular upper molar of the Centetide, I should
conclude that the main cone of this type of tooth, usually
termed the protocone, was really the paracone”; and he further
distinctly states in the recapitulation of his conclusions that
“the antero-external cone, or paracone above and the protoconid
below, is the primitive cone both in the molars and premolars.”
Consequently, the inference drawn by Osborn from the insec-
tivora is not in accord with Woodward’s own conclusions, which
were entirely opposed to the Cope-Osborn theory.

Again, I have previously shown (27) that in d.pm. 4 of the
dog and m. 1 of such a form as Cyon rutilans the protocone is
non-existent. I also adduced several other reasons derived
from embryology and comparative morphology which appear to
me to militate against the tritubercular theory. Moreover,
paleontology, upon which the upholders of this view mainly
rely, appears to me singularly deficient. In the first place, the
fossil forms are mainly known by the lower jaws only, and yet
it is generally agreed that the teeth of the upper jaw are those
which retain the most primitive characters.

The majority of these fossils have been found in the same
strata, and the evidence that the phylogenetic sequence is that
adopted by the upholders of the tritubercular theory appears
to be extremely hypothetical. I have in former papers entered
more into detail on this point; it is therefore unnecessary to
recapitulate, but Iam of the opinion that the paleontological
evidence is as deficient as the embryological is damaging, and
the absence of all proof in favour of the supposed rotation of
the cusps, which is the very foundation of the theory, is an
insuperable ditficulty, at least in the present state of knowledge.

The Multituberculate theory, suggested by Forsyth-Major
in (5) 1893 to account for the evolution of the rodent molars

THE EVOLUTION OF THE TEETH IN THE MAMMALIA. 139

. has met with but scanty recognition. That this theory can

apply to the premolars of such orders as marsupials, carnivores,
insectivores and primates, with their full numerical dentitions,
is scarcely possible. With the objections to the adoption of
such a view I have dealt elsewhere (27), with the reservation
that it might apply to the monotremes, rodents and ungulates.
Since then I have worked out the tooth-genesis in the rodentia,
and have concluded that for them a multituberculate origin
should be admitted. Taeker’s work on the tooth-genesis of the
ungulates would appear to lead to a different result, and it
_ would be interesting to reinvestigate the matter in the light of
more recent discoveries.

Having thus briefly passed in review the more important
hypotheses as to the molar and premolar evolution, and being
unable to conclude that any one of them is satisfactory, I
venture to advance a new theory which seems to me to be
nearer to a correct interpretation of the known facts.

This hypothesis is based on the importance, in the production
and development of cusps, of the cingulum. That this is an
extremely archaic structure is indisputable, being well marked
in the Anomodontia, for example Nythosaurus. Moreover, in
the early development of the teeth of existing mammals it is
_ proportionately very large. In the primitive reptilian condition
it would appear to have swrrownded the base of the primitive
haplodont cone, but in the process of evolution that portion of
the cingulum to the outer side of the primary cone, the external
cingulum, has disappeared to a considerable extent in the
majority of mammals, though its position may generally be
noted by the presence of a slight longitudinal rounded elevation.
The ends of the internal cingulum give rise to small anterior
and posterior cusps, a triconodont tooth, such as is found in
the Triassic Dromatherium Amphilestes and Microconodon, and
in the premolars of Amphitherium Prevostii of the Stonesfield
Slate, as described by Owen (19) and Goodrich (9). A precisely
similar type of tooth is to be seen in the milk incisors of the
dog, as previously figured (27). With an increase in size of these
anterior and posterior cusps, a tooth with three sub-equal cusps
in the same longitudinal row would be produced, such as exists
in the fossil Triconodon and in the premolars of the existing

140 DR H. W. MARETT TIMS.

felidee (fig. 1 and fig. 2B). The origin of these and other cusps
and their subsequent growth is probably due to mechanical
causes.

In the course of the further evolution and specialisation of

Fic. 1.—Upper third premolar of Hyena. External aspect, showing external
cingulum and small anterior and posterior cingulum cusps. (Mus. Zool.
Univ. Camb,) ~

the cheek-teeth there is a tendency in some forms to a disap-
pearance of the anterior cingulum-cusp, as in the upper carnassial
of the dog and bear (fig. 2A), while in the tiger both anterior

Fic. 24,—Upper fourth premolar of Canis familiaris, with external cingulum
and posterior cingulum cusp only, (Mus. Zool. Univ. Camb.)

Fic. 28.—Upper fourth premolar of Felis tigris, with external cingulum, and
enormously developed anterior and posterior cingulum cusps. (Mus. Zool.
Univ. Camb, )

and posterior cingulum cusps are very large. The anterior is
present and of large size in the lower carnassial of Ursus and
Meles; it is proportionally smaller in Lutra, Herpestes and
Canis, while in Felis it is altogether absent. The so-called
protocone of the premolars, where it exists, can be seen to rest
upon the internal cingulum; it is in fact an internal cingulum-
cusp, developed by mechanical agencies; where that cingulum
has disappeared or almost so, no protocone is to be found,

THE EVOLUTION OF THE TEETH IN THE MAMMALIA. 141

as for example in pm. 4 of Cyon rutilans and the anterior

4

premolars of most mammals.

The external cingulum usually disappears, leaving only a
slight longitudinal elevation along the outer side of the tooth
to indicate its position; but in Peralestes, Otocyon and the
Centetid, not only does the external cingulum persist, but it
gives rise to well marked cusps. The cause of this is difficult to
understand. It has been suggested (32) as being “of use to
insect-feeding animals,” but this would not apply to the
carnivorous Otocyon; and since this condition is absent in the
majority of the insectivora, the suggestion would not appear to
be very felicitous. Again, it cannot be due to the mechanical
stimulation caused by the interlocking of the teeth in closure of
the jaws, as external cingulum-cusps in these animals are equally
pronounced in both upper and lower teeth.

Thus far there is an accordance between this theory and
the embryological and paleontological evidence as to the
evolution of the mammalian premolars, the paracone repre-
senting the reptilian haplodont tooth, and being the first to
develop in the teeth of all forms hitherto examined. Moreover,
Scott has shown (24) from a comparison of fossil forms that

this cone is the primitive one phylogenetically.

The question now presents itself—Do the molars develop
along the same lines as the premolars? Scott (Joc. cit.), from a
consideration of the paleontological evidence only, concludes
that they do not. This conclusion appears at first sight to be
at variance with embryological results.

In attempting to outline the developmental history of the
true molars, it may be well to begin with a consideration of the

conditions present in the rodentia. These teeth first appear in
_ the form of a simple cone surrounded by a cingulum, of which
the external and internal parts are the most pronounced. The
____ primary cone ultimately gives rise to the antero-external portion

of the adult tooth, which may therefore on morphological grounds
be regarded as the paracone, though the individual cusps disappear
from the tooth even before it is erupted. The tooth-germ grows
in such a manner as to give rise to a posterior half, similar to
but smaller than the anterior; there is, in fact, an antero-
posterior reduplication. In this, presumptive evidence is

142 DR H. W. MARETT TIMS.

afforded in favour of conecrescence, though I have never yet
actually observed the fusion of two separate enamel-germs ;
nevertheless it is quite possible that in such primitive forms as
the rodents, dating back almost unchanged to the Lower Eocene
period, the early stages in the tooth-genesis may have become
abbreviated.

The rodent molars, according to the hypothesis under con-
sideration, represent a simple ancestral type, in which two
primary cones, with their internal and external cingula, have
become fused, the external lasting only for a time, and disappear-
ing before the tooth has erupted. The molars of the greater
number of rodents seem to be derived from the fusion of two
primitive cones only, but in exceptional cases, as for example
Arvicola amphibius, it might be inferred, judging from the adult
teeth, that four were originally involved, while, as an intermediate
condition, the posterior upper molars of Mus and Cricetus and
the posterior tooth in the mandibular ramus of Gerbillus indicus
give evidence of the concrescence of three primary cones. It
would be extremely instructive to investigate the tooth-genesis
in such forms.

In the Multituberculata, which, agreeing with Forsyth-Major,
I regard as the precursors of the rodentia (1), there appears,
according to this hypothesis, to be a fusion of the same primitive
type of tooth, but im these, as might be expected, the external
cingulum has not yet aborted in the majority of forms, though
the process has already commenced in some of the Polymasto-
dontide, for example P. tabensis, and in m. 2 of Meniscoessus (18).
The further complication in existing rodents is due to the
involutions of the enamel, whereas in the multituberculata this
does not exist, the greater complexity of tooth-pattern being
brought about by increase in the number of teeth which have
become fused. The number of such teeth so involved seems to
vary in different cases. In Ctenacodon potens there appear to
be four, while in Polymastudon attenwatus there are at least
seven or eight. Thus the so-called true molars of the Rodentia
and Multituberculata conform to the same general type as the
premolars of the other Eutheria, the tendency likewise being the
suppression of the external cingulum; the difference being that
in the premolars the anterior and posterior cusps are develop-

THE EVOLUTION OF THE TEETH IN THE MAMMALIA. 143

ments of the anterior and posterior portions respectively of the

:: surrounding cingulum; in the molars an antero-posterior fusion

of originally separate teeth has led to the suppression of these
parts and given rise to the multituberculate pattern.

From a comparison of Taeker’s account of the development of
the ungulate molar (26) with that of my own researches in the
Caviidee, the hypothesis under consideration would seem to me
to be capable of similar application. In the majority of ungulates
the molars might also be produced by the fusion of two originally
distinct teeth. Such a primitive type with but little further
complication is to be observed in the unworn molars of Anchi-
therium from the Lower Eocene (fig. 3B), while the corresponding
unused teeth of the existing horse show but slight further changes,

Fic. 3a.—Crown surface of upper first molar of Cyon rutilans. (Zool. Mus, Roy.
Coll. Sei. Lond.) ‘

Fie. 3n.—Crown surface of unworn molar of Anchitherium. (After Flower and
Lydekker. )

4 except in the increased size and development of the internal
_ eingulum. Comparison of these teeth with those of the rodents

Cavia and Lepus present a general similarity in type, though in

the latter forms the teeth have become much more compressed
__antero-posteriorly. The increased complexity of the cheek-teeth
_ of the rodent Muride, caused by enamel involution, finds
analogy in the teeth of that extremely interesting form Hyrax
capensis and in those of the rhinoceros, while the more bunodont

molars of the Suide are comparable to those of the unworn
teeth of the Hystricide. The pattern of tooth found in the
Bovide and Cervide would not appear to find any expression
among rodent types, but the mode of their evolution seems to

144 DR H. W. MARETT TIMS.

run on parallel lines with that of the more complex teeth of the
carnivora, as exemplified by Canis aureus (fig, 4), and to which
subsequent reference will be made.

In the molars of the Proboscidea we find analogy between the

Fie. 4a. —Crown surface of molar and premolar of Nomorkeaes goral, (Mus.
Zool. Univ. Camb.)

Fic. 48.—Crown surface of upper first molar of Canis aureus. (Zool. Mus, Roy.
Coll. Sci. Lond.)

teeth of the fossil Polymastodon and existing Caviide and
Leporide; fusion of a number of teeth with considerable
antero-posterior compression, but no further complication due

Fic. 54,—Crown surface of molar teeth of Rabbit. x 4. (Mus, Zool. Univ.
Camb.)

Fic. 58.—Crown surface of molar tooth of Hlephas antiguus, from the Cambridge
Gravel, x4. (Mus. Zool. Univ. Camb.)

to the production of cingulum-cusps or infoldings of enamel.
The well known molars of the Elephant and Mastodon (fig. 58)

THE EVOLUTION OF THE TEETH IN THE MAMMALIA, 145

have numerous transverse ridges grouped in pairs, each of which

‘might be regarded as representing the complete cingulum of an
- originally separate tooth, longitudinally compressed, and con-
_ siderably elongated in the transverse axis.

Viewing the molar genesis in the dog in the light of the
knowledge obtained from the rodents, the same interpretation
seems justifiable. The condition obtaining in the premolars of
the carnivora is simple on the cingulum-cusp hypothesis, but
its application to the molars offered greater obstacles. The
two main external cones might be so explained, were it not
for the fact that distinct and well marked anterior and posterior
cingula were also present. By admitting the antero-posterior
fusion of separate haplodont cones of the same series with
their cingula, the difficulties appear to me to vanish. The two ©
main external cones of the molars so general throughout the
mammalia represent two originally separate haplodont teeth,
the opposed cingula being fused, and giving rise to the tooth
substance between the main cones, the anterior cingulum of
the anterior and the posterior cingulum of the posterior moiety
persisting as the corresponding parts of the adult tooth. By
the interlocking of the longitudinal series of cusps in the teeth
of the upper and lower jaws, the internal cingula have been

wedged inwards, forming a more transversely elongated tooth,
which would correspondingly produce a more efficient crushing
_ surface. Such a simple form of tooth is to be seen in Perameles,
Perigale, and a number of other marsupials, as well as in the
primitive molar of Cyon rutilans (fig. 3A). Accompanying
the increased severance of the internal cingulum from the
primary cones in a mesial direction, there is a gradual addition
in the number of cusps, all of which become developed in the
intervening space, the production of such being doubtless due
___ to the mechanical stimulation when the teeth of the opposing
_ jaws are brought into contact. Among the dogs this is carried
to an extreme in the molars of the jackal (Canis awreus) (fig. 4B).
_ It is unnecessary to press this point further in its applica-
tion to the other mammalian orders. Suffice it to say that I
have dealt with what I conceive to be the most difficult of
interpretation, the teeth of the Insectivora, Cheiroptera and
Primates offering no special obstacles.
VOL. XXXVII. (NS. VOL. XVIL)—JAN, 1903, 10

146 DR H. W. MARETT TIMS.

We must now revert once more to the question raised by
Scott: Do the molars and premolars follow the same line of
evolution? The answer to be given from the foregoing con-
siderations is that they do in so far as the early stages are
concerned, but that in the later stages of the developmental
history they diverge. In the premolars there is no sufficient
evidence of concrescence, but they specialise along their own
lines in the growth of the cingulum and the production upon
it of secondary cusps, principally anteriorly and _ posteriorly,
though the addition of cusps upon the internal and more rarely
external cingulum takes place. In the molars the complexity
of tooth pattern is chiefly due to the longitudinal fusion of
primitively simple teeth, further complications such as those
produced by involutions of the enamel being quite secondary,
and developed within the limits of individual groups. Such a con-
clusion raises further minor points, which must not be omitted.
(1) If the two main external cones of the molars represent two
teeth of the same series, and are therefore, so to speak, of equal
phylogenetic value, how comes it that in all the published
results of investigations into tooth-genesis the anterior cone
develops first in point of time, and is therefore of prime
ontogenetic value? To this I would answer, that it is in
accord with the recognised fact that the molars develop in
succession from before backwards, the posterior ‘wisdom’
teeth being the last to appear. The order of evolution would
therefore be first the paracone, then the metacone of m. 1, next
the. paracone of m. 2, followed by its corresponding metacone,
and so throughout the series.

(2) In view of the above conclusion, what interpretation is to
be placed upon the teeth usually regarded as premolars, found in
certain of the multituberculata; instance the three lower posterior
premolars of Plagiaulax minor? I have elsewhere (29) thrown
doubt upon the validity of the generally accepted distinction
between molars and premolars; but assuming it to be correct,
Smith Woodward asserts (33) that in Plagiaulax “nothing is
known of the mode of succession, but these teeth are usually
termed premolars.” Presumably, the reason is to be found in
an attempt to harmonise the dental formule—4 premolars and
2 molars—with that of recent mammals. This is unnecessary,

THE EVOLUTION OF THE: TEETH IN THE MAMMALIA. 147

‘since Osborn has shown (16) in his paper“ On the Structure
and Classification of Mesozoic Mammalia” that the dental
formula of the primitive heterodont mammal should be con-
‘sidered asi. 4, c. 1, pm.4,m.8. In my opinion the three posterior
premolars of Plagiaulax partake much more of the molar
pattern, and I would certainly be disposed to regard them as
such. The anterior premolar is too much reduced to express
any definite opinion.

(3) If the entire molar tooth has been evolved from the
fusion of teeth of the same series, as suggested, what has been
the fate of the preceding milk dentition? It has been men-
tioned already that the advocates of concrescence ‘per se’
regard the molars as the result of the fusion of teeth of three
different series.

The presence of concentric epithelial bodies, such as occur in
Canis, Gymnura and Ornithorhynchus, seems entirely against
the view of the milk teeth forming the outer portion of the
functional molars. Now, it is well known that the deciduous
teeth develop slightly in front and to the outer side of their
successors. It may be readily conceived that in an antero-
posterior fusion such as above described the milk series would
__ have little or no room to develop, while the larger and more
_ funetional the molars became the more they would withdraw
nourishment, and thus doubly tend to prevent the teeth of the

‘deciduous dentition coming to perfection.

Lastly, two other questions suggest themselves: What factors

_ have caused the fusion in the molar region and not in the
_ premolar, and why have the latter departed on a special line

of evolution? Shortening of the jaws has probably been the

"principal factor, acting mainly on the posterior end of the bone,

coupled with the larger size and number of the teeth in this

: situation; whereas, in the premolar region, the teeth are

fewer in number, and the early loss of some in many animals
causing a diastema, does not tend to produce so much crowding,
and permits of a greater longitudinal growth of the individual
teeth, in adaptation to the different physiological requirements.

It is impossible within reasonable limits to discuss the
application of this hypothesis at any great length in reference
to all the mammalian orders. Suflicient has, I hope, been

148 DR H. W. MARETT TIMS.

stated to fully explain the underlying idea as to mammalian
tooth-genesis; and though there may be difficulties as to
its adaptation in every instance, it would appear to me
more capable of universal application, both to recent and
extinct forms, than any of the theories previously suggested,
and at the same time to be more in accordance with the
known facts of embryology and paleontology.

BIBLIOGRAPHY.

(1) Ameeurno, F., “Sur lévolution des Dents des Mammiféres,”
Boll. Acad. Nac. Ciencias en Cordoba, 1894, pp. 381-517.

(2) Corz, E. D., “The Homologies and Origin of the Types of
Molar Teeth in the Mammalia Educabilia,” Journ. Acad. Nat. Sci.,
Philadelphia, 1874, and many subsequent papers. tL:

(3) Cuvigr, F., ‘‘ Des Dents des Mammiftres,” Paris, 1825.

(4) Dyzowsx1, B., “Studien iiber die Siiugethierziihne,” Behand.
der Kaiserlich-kéniglichen Zoolog. botan. Gessel. in Wien, 1889,
Bd. xxxix. pp. 3-7.

(5) Forsyra-Masor, C. IL, “On some Miocene Squirrels, with
remarks on the Dentition and Classification of the Sciurine,” Proc.
Zool. Soc. Lond., 1893, pp. 179.

(6) Gavow, Hans, ‘“ Amphibia and Reptiles,” Cambridge Natural
History, vol. viii., London, 1901.

(7) Gaupry, A., “Enchainements du Monde animal dans les
Temps geologiques ; Mammiféres Tertiares,” Paris, 1878.

(8) Gervais, Paun, ‘Histoire naturelle des Mammiféres,” Paris,
1854.

(9) Goopricu, E. §., “On the Fossi] Mammalia of the Stonesfield
Slate,” Quart. Journ. Mier. Sci., vol. xxxv., 1894, pp. 407.

(10) Harrison, H. Spencer, “ Hatteria punctata: its Dentitions
and its Incubation Period,” Anat, Anz., Bd. xx. pp. 145-158.

(11) Huxuzy, T. H., “Tegumentary Organs,” Art. in Todd's
Encyclopedia, 1855-56. pe:

(12) Huxtey, T. H., “On the Characters of the Pelvis in the
Mammalia, etc.,” Proc. Roy. Soc. Lond., No. 194, 1879, pp.
394-405. y

(13) Ktxenruat, W., “ Entwickelungsgeschicte Untersuchungen
am Pinnipediergebisse,” Jenaische Zeitschr. f. naturw., Bd, xxviii.,
1893, p. 76. .

(14) Ktxentuat, W., “ Die Bezahnung der Zahnwale,” Denkschr.
d. med-naturw. Gesselsch., Bd. iii., 1893, pp. 387-448.

(15) Mivart, Sr J., ‘‘On the Osteology of the Insectivora,”
Journ, Anat. and Phys., vol. i. p. 281, and vol. i. p. 117.

(16) Osporn, H. F., “On the Structure and Classification of the
Mesozoic Mammalia,” Journ. Acad. Nat. Sci., Philadelphia, vol. ix.
p. 186.

THE EVOLUTION OF THE TEETH IN THE MAMMALIA. 149

(17) Ospory, H. F., “Tritubereuly,” American Naturalist, vol.
xxxi., 1897, pp. 993-1016.

(18) Osporn, H. F., and Earie, Cu., “Fossil Mammals of the
Puerco Beds,” Bull. Amer. Mus. Nat. Hist., vol. vii., 1895, pp. 1-70.

(19) Owey, R., “Monograph of the Fossil Mammalia of the
Mesozoic Formations,” Monogr. Paleontograph. Soc., vol. xxiv.

(20) Proceedings of the Fourth International Congress of Zoology,
Cambridge, 1898, “ The Origin of Mammals,” pp. 68-75.

(21) Rész, C., “Ueber die Entstehung und Formabinderungen
der Menschlichen molaren,” Anat. Anz., Bd. vii., 1892, pp. 392-421.

(22) Rosz, C., “Ueber die Zahnentwickelung der Beutelthiere,”
Anat. Anz., Bd. vii., 1892, pp. 692-707.

(23) Rész, C., “ Ueber die Zahnentwickelung vom Chameleon,”
Anat. Anz., Bd. viii., 1893, pp. 566-577.

(24) Scorr, W. B., “The Evolution of the Premolar Teeth in the
-Mammalia,” Proc. Acad. Nat. Sci., Philadelphia, 1892, p. 405.

(25) Semon, R., “Die ifussere Entwickelung des Ceratodus
¥orsteri,” Zovoloy. Forschungsreisen in Australien und dem Malayischen
Archipel, Bd. i., Jena, 1893.

(26) Taxer, J., “Zur Kenntniss der Odontogenese bei Ungulaten,”
Inaugural Dissertation, Dorpat, 1892.

(27) Trs, H. W. Marert, ‘‘On the Tooth-genesis in the Canide,”

Journ. (Zool.) Linnean Soc. Lond., vol. xxv., 1896, pp. 445-480.
(28) Tims, H. W. Marert, “ On the Tooth-genesis in the Caviide,”
Journ. (Zool.) Linnean Soc, Lond., vol. xxviii., 1901, pp. 261-290.

(29) Trws, H. W. Marert, “ On the Succession and Homologies
-of the Molar and Premolar Teeth in the Mammalia,” Journ. Anat.
and Phys., vol. xxxvi., 1902, pp. 321-343.

(30) Wines, O., “Om Pattedyrenes Tandskifte isaer med Hensyn
til Taendernes Former,” Vidensk. Meddel. fra den naturk. Foren. 7.
_Kjobenhavn, 1882, pp. 11-52.

_ (31) Woopwarp, M. F., “On the Succession and Genesis of the
Mammalian Teeth,” Science Progress, vol. i., 1894, pp. 438-453.
(32) Woopwarp, M. F., “On the Teeth of certain Insectivora,”

| Proc. Zool. Soc. Lond., 1896, pp. 557-594.

(33) Woopwarp, A. "Sarre, “Outlines of Vertebrate Paleontology,”
Cambridge Natural Science Manuals, Cambridge, 1898.

THE FORM OF THE DILATED CEREBRAL VENTRICLES.
IN CHRONIC BRAIN ATROPHY. By J. O. WAKELIN
Barratt, M.D. Lond., F.R.C.S. Eng., Pathologist te the West
hiding Asylum, Wakefield.

WHEN chronic wasting of the cerebrum occurs, the atrophy of
the gyri, with corresponding widening of the sulci and distension
of the pia-arachnoid with fluid, forms a striking appearance:
when the brain before removal is viewed in siti from above,
but the accompanying ventricular dilatation in such cases is
less readily studied, because the form of the ventricles is altered
as the brain is cut up in order to bring these cavities into view.
The wasting of brain tissue may be due to a disappearance of
whole neurons, or merely of nerve-cell processes, the extent to
which these two degenerations occur in individual cases being
as yet imperfectly ascertained. The bulk of the axis-cylinders
and their offshoots, with their myelin sheaths, and that of the
corresponding protoplasmic extensions, taken together, must
frequently if not generally exceed that of the cell-bodies, so-
that the atrophy may in some cases be much more due to
disappearance of the former than of the latter. The wasting
of cerebral gyri is due to both forms, that is, atrophy of cell-
bodies and of cell-processes. The enlargement of the lateral
and to a less extent of the third ventricles is, however, due
essentially to an atrophy of the thick masses of white substance
which come into relation with these cavities. It would
naturally follow that if, in a wasted cerebrum, atrophy largely
preponderated in particular situations, say in the frontal lobes,.
such atrophy would be indicated by a disproportionate enlarge-
ment of a corresponding portion of the ventricular space; and
similarly, atrophy elsewhere would produce correlated local
ventricular dilatation. With a view of studying more fully
the general form of the ventricular dilatation occurring in
chronic brain atrophy, and further, of ascertaining whether

any such disproportionate wasting of white matter, as evidenced

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 151

by enlargement of the ventricular cavity, occurs, the following
investigation was undertaken.

In order better to study the form of the dilated ventricles,
plaster casts of these cavities were prepared. In taking out
the brain, great care was necessary to avoid altering its shape.
As soon as the brain was removed from the skull, the
mesencephalon was cut across at its junction with the pons
Varolii, and the cerebrum placed in a saturated solution of
bichromate of potassium, to which 5 per cent. of formol was
sometimes but not always added. In this liquid the cerebrum
at first floated, subsequently gradually sinking as it became
penetrated by the hardening fluid. During removal a certain
amount of fiuid necessarily escaped from the ventricles. To
avoid the accompanying alteration in size and shape of the
ventricular cavity which this entails, some of the bichromate
solution was injected into the ventricles through a glass nozzle
inserted into the aqueduct of Sylvius, and the injection was
continued until some of the fluid returned again through the
aqueduct. By this method the shape of the cerebrum and its
ventricles was preserved with the least possible alteration.

_ At the end of from three weeks to two months the brain
was sufficiently hardened. It was then placed with the frontal
lobes directed downwards and the occipital lobes upwards.. The
occipital lobes were now sliced off from above downwards until
the tips of the posterior cornua were reached. Smali openings
being made into these horns in order to permit the passage
of fluid through them, plaster of Paris was then injected into
the aqueduct of Sylvius until it welled up through the minute
openings in the apices of the posterior cornua just referred to.
It was necessary to repeat the injection many times, in con-
sequence of the dilution of the plaster of Paris with the fluid
already present in the ventricles. As soon as the plaster of
Paris commenced to set, the orifice of the aqueduct was closed,
and when setting was completed, the brain substance was cut
away bit by bit. Great care is required to avoid breaking the
east, especially in removing the septum lucidum. More often
than not, however, fracture occurs at the foramen of Monro,
but this is not of great consequence, as, from the irregular
shape of the broken surfaces, reunion can be effected without

152 DR J. O. WAKELIN BARRATT.

any alteration of the relation of the fragments. A cast of the
fourth ventricle cannot satisfactorily be made, owing to the
escape of plaster into the meshes of the pia-arachnoid by the
foramen of Magendie and the openings in the lateral recesses.

When a cast of the cerebral ventricles has been made in
this way, the brain itself is necessarily destroyed in the process,
so that relation of the form of the ventricular cavity to that
of the cerebrum cannot be observed. This difficulty can in
part be avoided by making thick frontal sections, placing them
together, having previously made sketches of the cut surfaces
to scale, and then making a cast. In this way a record both
of the form of the ventricles and of their form-relations to the
cerebrum is obtained. It is, however, more convenient to
study the two separately.

The number of casts of the cerebral ventricles upon which
the present observations are based is six. Of these, four were
from cases of dementia occurring in patients whose ages at
death ranged from 68 to 77 years, and two were from cases
of general paralysis of the insane, aged respectively 51 and 55
years.

The dilated ventricular space of the cerebrum consists of
three parts, corresponding to the lateral and third ventricles

(figs. 1 to 4). Of these, the two former, which are approximately:

but not accurately symmetrical in shape, are situated on each
side of the mesial sagittal plane of the skull, and consist of a
body flattened obliquely from above downwards, its inner being
lower than its outer border, and three large processes known
as the anterior, posterior and inferior cornua, the first arising
from the anterior extremity of the body and the two last from
its posterior end. The anterior and posterior cornua are
flattened from side to side, while the inferior cornua are
flattened from above downwards. The anterior cornua are
separated from each other by a narrow, the posterior cornua
by a wide interval; the inferior cornua, which at their origin
curve outwards, turn inwards as they approach their termina-
tions, and thus form a concavity on each side of the mesial
plane (fig. 3B).

The cavity of the third ventricle lies within the thalamen-
cephalon and is connected on each side by a narrow neck with

,

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 153

the lateral ventricles at the junction of body and anterior

horn.

__In its division into three parts the dilated cerebral ventricular
space occurring in brain atrophy resembles the normal ventricular
cavity,’ but here the resemblance ceases, for both in its large
size and still more in its shape the former diverges from the
latter. This divergence is greater the larger the dilatation, and
affects not only the general form of the ventricular space, but
involves also in varying degree that of each of its divisions.

The six ventricular cavities examined vary much in size and
also in form. The smallest (figs. 14, 1B) approaches most
nearly to the form and dimensions of the normal ventricles,

sqm soe!!
4 C2

\,

>

Fig. 14. Cast of the ventricles of the cerebrum, seen from the right side. Case
1. Male, aged 68 years, suffering from dementia. The ventricular cavity is
moderately dilated, so that the lateral ventricles approach the expanded
seale-like character of the undilated lateral ventricular spaces, and the third
ventricle presents some resemblance to the slit-like cavity exhibited in a
normal brain, The lateral ventricles are not perfectly symmetrical, the left
anterior cornu, a.h., projecting more forward than the right. The inferior
cornua are not present, the cavity of these horns being in part obliterated,
through their upper and lower surfaces coming in contact posteriorly. The
posterior horns, p.h., are short, almost sessile, and are directed a little out-
wards, Each is deeply grooved on its inner surface by the calcar avis, ¢./.
The details of structure are described in the text.

This and the following sketches are of the natural size.

while the others diverge therefrom in proportion to their size.
This divergence affects the lateral ventricles far more than the
third, which, while it increases in its lateral dimensions, is other-

Cp. ‘The Form and Form-relations of the Human Ventricular Cavity,”
Journ, of Anat. and Physiol., vol. xxxvi. pp. 106-126, 1902,

154 DR J. O. WAKELIN BARRATT.

wise but little altered in aspect (cp. figs. 1A and 4). The
descending horns are not always represented in the casts (figs.
1 and 2). This arises from the circumstance that the inferior
cornua are flattened from above downwards, the upper and lower
surfaces of their lining membrane approaching each other or
actually coming into contact over a portion of their extent.
Perhaps this may be partly caused by the brain being floated
with its lower surface upwards in the hardening fluid, when the
temporal lobes tend to become flattened, but it is probably due
chiefly to the form the brain assumes during life when, in
consequence of the lesser specific gravity of the ventricular
fluid (1:006) as compared with that of the brain substance
(1:038), the inferior cornua tend to become pressed upon from
above. In most of the cases (four out of six) the right inferior
horn was larger than the left (ep. figs. 24, 2B, 3A, 3B).

The flattening of the bodies and cornua of the lateral ven-
tricles becomes less marked the greater the dilatation of these
cavities. Figs. 1 to 4, which represent a series of ventricular
spaces arranged in progressive order and all drawn to the same
scale, illustrate this point. The anterior cornua and bodies of
the lateral ventricular cavities are the first to lose the strongly
flattened character peculiar to the undilated condition; the loss,
though marked, is less conspicuous in the posterior and inferior
cornua. The third ventricular space also broadens out from
side to side as the general ventricular space enlarges, but this.
increase in size is not in the same proportion as that of the
lateral ventricular space, as the figures indicate.

Asymmetry of the two lateral ventricles is noted in every
ventricular space examined. It is not, however, extreme in
degree. It affects the bodies (cp. fig. 1B) less than the cornua ;
of the latter, the anterior cornua are but little affected, the
inferior cornua are more decidedly unequal, and the posterior
cornua, except in the first case (figs. 1a, 1B), are markedly
asymmetrical.

The six ventricular cavities examined preserve « resemblance:
in general form sufficient to permit of their being arranged in
a graduated series, which corresponds also to their increase in
size. The change of form from the flattened character of the
normal to the expanded type of the considerably dilated ven-

—— a ee. ee hm lhl

i ee li, a a

ee eel ee YT AS

4

ee

——
DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 155

tricular space is best seen in the bodies and anterior cornua,
and to a less extent in the inferior cornua. In the posterior
cornua, however, there is, as the figures indicate, so much differ-
ence in form exhibited that no such gradation is recognisable.
Thus in two cases (figs. 24, 2B and 4) the tips of the posterior
horns are directed inwards, the right in each case more than
the left, while in two other cases (figs. 1a, 1B, 3a and 3B)
no such incurving occurs, the posterior horns being short and
stumpy. There is, therefore, in the case of the posterior cornua,
not only lateral asymmetry in the individual ventricular spaces

Fic. 1s.

Fig. 1z. The same cast as exhibited in fig. 1a., seen from above. In addition to
the inequality of the lateral ventricles referred to above, it is seen that the
septum lucidum, s./., is displaced to the right in part of its extent above.
The upper surfaces of the lateral ventricles are flattened from side to side,
and exhibit some degree of transverse furrowing opposite the corpus callosum,
especially in front and behind.

studied, but also serial asymmetry. Careful comparison of one
with another has failed to furnish me with any suggestion as
to the significance of this variation of form in different cases.
The third ventricle does not vary very much in form. Its
length from before backwards depends in part upon the extent
to which the supra-pineal recess, s.7., is developed. The obliquity
and curvature of this portion of the ventricular space of the
cerebrum is altered as dilatation occurs (cp. fig. 14 with fig. 4).
This appears to be due to the corpus callosum becoming raised

156 DR J. O. WAKELIN BARRATT.

as dilatation occurs, and carrying with it the posterior extremity
of the third ventricle, while the anterior and inferior angle
preserves its position unaltered or descends a little.

The lateral ventricles are, as already stated, of nearly equal
dimensions. In two cases (figs. 3 and 4) the right lateral
ventricle was slightly larger than the left; the other two (figs.
1 and 2) were little different in size. The increase in size which
the lateral ventricles undergo as the general ventricular cavity
enlarges is far greater than that assumed by the third ventricle,
which always forms but a very small portion of the ventricular
space. When the lateral ventricles undergo an increase in
size, the enlargement affects all parts more or less equally with
the exception of the descending horns referred to above (figs.
1 to 4). But it is to be noted that in the cases examined there
is a definite predominance in size of the anterior cornua and
adjoining portion of the bodies over the rest of the lateral
ventricles. This fact is of importance, in view of the prepon-
derant wasting of cell-bodies in definite regions of the brain
mantle in certain cases of atrophy.1 On comparing the casts
it is noted that, as the enlargement increases, the body and
anterior and posterior cornua, taken together, form a curve,
_ which is convex upwards (figs. 1 to 4).

Having indicated the general form of the cerebral ventricular
space, we now pass to details of structure of this cavity.

The third ventricle, instead of being a narrow plate-like
structure, perforated by a centrally placed large aperture repre-
senting the middle commissure, m.c., acquires considerable
breadth from side to side, while the opening for the middle
commissure becomes a narrow canal (figs. 14, 24, 3a). Its
original shape is somewhat triangular (fig. 14), presenting
an anterior, an upper and a lower border, and two lateral
surfaces. Although its shape alters as dilatation occurs, it
will nevertheless be convenient to keep to the same division
into three borders, noting such modifications as are exhibited.

The third ventricle exhibits on its anterior border, below

1 Compare an illustration of nerve-cell degeneration in the frontal cortex, the
occipital cortex remaining unaltered, in general paralysis of the insane, given in
the Croonian Lectures, 1900, by Dr F. W. Mott, F.R.S., Brit, Med. Jowrn., 1900,
ii. p. 82.

2
be

"ert. = 7

SS ee ee ee ee

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 157

the situation of the foramen of Monro, a-deep transverse groove
formed by the anterior white commissure, a.c. (figs. 1a, 2A, 2B,
3A, 4). Below this is a flattened border, which is sometimes
convex, sometimes concave, corresponding to the lamina cinerea,
-and terminating in a pointed process, directed downwards and
forwards, lying in the supra-optic recess, 0.7. Beneath this is a
deep groove formed by the optic commissure, ch., bounded pos-
teriorly by a conical projection, also directed downwards and
forwards, representing the interior of the infundibulum.

From this point to the upper opening of the aqueduct of

Ms,
re

we

MN,
ii

ths? peag th me échor.ac ne ah

Fic. 2a.

Fig. 2A. Cast of the ventricles of the cerebrum, seen from the right side. Case

2. Male, aged 69 years, suffering from dementia. The ventricular cavity is
more dilated than in the preceding case. The lateral ventricles are nearly
but not quite symmetrical. The left inferior horn, 7.4., is completely and
the right partially obliterated by contact of its upper and lower surfaces.
The left posterior horn, p./., is shorter than the right, which is thinner, and
curved inwards at its extremity ; each is deeply grooved by the corresponding
calear avis, c.f. The supra-pineal recess, s.7., is small.

Observe in this and the succeeding figures the marked enlargement of the
lateral ventricles as compared with the third ; the former project much more
than the latter into the frontal and occipital lobes, and in addition reach up-
wards to an unusually high level opposite the vertex, Note also the altered
form and direction of the cavity of the third ventricle and the narrowed canal
for the middle commissure,

Sylvius, ag., which is represented by a process directed down-
wards and backwards, the lower border of the cavity of the third

158 DR J. O. WAKELIN BARRATT.

ventricle forms a concave curve, varying in character in different
eases. Anteriorly it corresponds to the tuber cinereum and
posterior perforated space, and posteriorly it represents the
upper limit of the tegmentum mesencephali. The distance
between the anterior end of the inferior border and the upper
opening of the aqueduct of Sylvius increases as the third
ventricular space becomes dilated, and this considerably changes
the form of the anterior inferior end of this cavity, as is shown
in the figures. Above the upper end of the aqueduct of Sylvius

Fic, 28,

Fig. 28. The same cast as exhibited in fig. 24., seen from before. The massive
character of the bodies and anterior cornua of the lateral ventricular spaces
and the increased width of the third ventricular cavity are very striking.
The surfaces of the lateral ventricles in contact with the caudate nuclei, 2.c.,
and the optic thalami, ¢h., are well seen, as is also the ridge separating
them, corresponding to the tenia semicircularis. The surfaces in contact
with the optic thalami exhibit deep but narrow grooves for the choroid
plexuses, ch.p. The trigona ventriculorum, ¢.v., are also seen. On the
anterior aspect of the third ventricle is the deep groove for the anterior com-
missure, @.¢. ;

is a groove, p.c., corresponding to the posterior white commissure ;
above this again are projections corresponding to the pineal and
supra-pineal recesses, p.7. and s.7r., the former being small, and
the latter, which is large (figs. 3A, 3B) and irregular in shape, being
not unfrequently multilocular, and consequently difficult to cast.

_‘DILA IL TED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 159

That this irregularity in shape is not due to an occasional
escape of plaster from the cavity of the third ventricle into the
meshes of the pia mater is shown by the fact that this recess
ean often be seen to be irregularly enlarged and distended with
__ fluid when the brain is placed with its base uppermost, and the
erebellum and pons, together with the mesencephalon, are
separated from the splenium of the corpus callosum. This
enlargement may be much greater than is shown in the
illustrations.

Superiorly, the third ventricle presents a slightly convex
border, on which are two parallel grooves (sometimes only one)
corresponding to the choroid plexuses of this ventricle. The
upper border is slightly convex or nearly straight when only
slight dilatation of the cerebral ventricular space is present.
When marked dilatation occurs, it becomes much more convex.
The third ventricular cavity becomes broad and stumpy at its
posterior end, that is, at the junction of superior and inferior
borders, when there is marked dilatation. .

The outer surfaces of the third ventricle are somewhat
__ irregularly rounded. An antero-posterior ridge, not very sharply
defined, is met with immediately below the middle commissure,
_ m<e,, dividing each outer surface into an upper portion, some-
times slightly convex, sometimes presenting a shallow groove
_ running from before backwards, and a lower portion convex in
outline ; the former corresponds to the optic thalamus, the latter

_ to the olfactory field, the internal capsule, and the sub-thalamic
= tegmentum. Anteriorly are observed the processes connecting
the third with the lateral ventricle, f.m.; these generally increase
in size pari passw with that of the lateral ventricles, and are
7 _ grooved internally and in front for the anterior pillars of the
_ fornix. Between these two processes is a shallow groove,
__ €orresponding to the fornix at its junction with the base of the
» saga lucidum.

~ The anterior cornua of the lateral ventricles, a.h. , diverge from
each other as they pass forwards, and have the shape indicated
in the figures. They have lost the flattened scale-like character
of the undilated cornua, and have become expanded in all direc-
tions, passing forwards with an oblique direction, and forming
coarse blunt projections. In the situation of the septum lucidum,

160 ; DR J, 0. WAKELIN BARRATT.

s.l., the lateral ventricles approach each other very closely. None -
of these casts, however, show a disappearance of this interval.
It may here be observed that as the size of the ventricles
increases in chronic brain atrophy, the septum lucidum enlarges
in extent and becomes thinned ; occasionally, when the dilatation
of the ventricles is exceedingly large, the nervous material may
here and there be absent, but the ependymal wall still remains,
and is represented by a smooth flattened pyriform surface on the

Ih ch
sr pr poag th me ¢ chorac {4

ph
Fie. 3a.

Fig. 3A. Cast of the ventricles of the cerebrum, seen from the right side. Case
3. Male, aged 51 years, suffering from general paralysis of the insane. The
ventricular cavity is larger than in the two preceding cases, the chief increase
being in the lateral ventricles. The form of the third ventricle is similar
to that seen in fig. 2a. Both inferior cornua are present in the cast, the
right being of large size.

inner side of the cornu (mus., fig. 4). Sometimes the cavity of
the septum lucidum becomes filled with plaster, and occasionally
also small collections of plaster, elongated in form and placed
antero-posteriorly, are met with beneath or in the velum inter-
positum, on each side of the upper border of the third ventricle.

1 In an illustration, after Welcker, in Quain’s Anatomy, 10th edit., vol.
iii, pt. 1, p. 126, the anterior horns and bodies of the lateral ventricles are
represented too far apart, the interval occupied by the septum lucidum exceeding
a centimetre in transverse measurement,

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 161

The upper surface of each anterior cornu is convex, and is
continued over the front and lower part of the horn; this
surface corresponds to the genu of the corpus callosum, and
presents more or less defined grooves radiating from the anterior
end of the interval for the septum lucidum, and indicating the
forceps minor (figs. 1B, 2B). The outer surface of the anterior
cornu presents a large shallow depression, x.c., for the head of
the caudate nucleus. It is directed obliquely outwards and
downwards; in consequence of this obliquity the anterior cornua
are much broader above than below (fig. 2B). The outer border
of each anterior cornu becomes very broad and rounded, especially
above, as the ventricles become largely dilated ;1 it thus differs
very strikingly from the sharp edge which exists in the un-
dilated condition.

The body of the lateral ventricle, as it increases in size, be-
comes thick and broad, so that in section it tends to become
elliptical (figs. 14, 14 with figs. 3a, 3B, 4). On the under
surface of the body of the lateral ventricle is seen a flattened
elongated depression looking downwards and outwards, x.c.,
(figs. 14, 2A, 2B, 3A, 3B), corresponding to the caudate
nucleus, and continuous with the large depression on the outer
aspect of the anterior horn; while, internal to and slightly below
this, is another flattened surface, ¢/., concave from before back-
wards, corresponding to that portion of the optic thalamus which
appears in the lateral ventricle, and presenting a deep antero-
posterior groove, ch.p., formed by the choroid plexus of the
lateral ventricle, internal to which this surface comes into
relation with the lateral band of the fornix. This surface is
separated from the groove for the tail of the caudate nucleus by
a ridge corresponding to the tenia semicircularis. The upper
surface of the body of the lateral ventricle is convex from before
backwards, and flattened or slightly convex from side to side.
_ It is marked by transverse grooves, which are apparently caused
by an irregular atrophy of the transverse bundles of the corpus
callosum. The outer border of the body of the lateral ventricle
becomes remarkably thickened and rounded as the dilatation

1 The adjoining part of the body is similarly affected, This corresponds to the
preponderant wasting of the brain mantle in the region of the frontal and parietal
lobes on their outer aspect seen in brain atrophy of the insane,

VOL. XXXVII. (N.S. VOL. XVII. )—JAN, 1908. 11

162 DR J. O. WAKELIN BARRATT.

becomes considerable. At the outer aspect of the body of the
ventricle, which is at a lower level than the outer border, is a
flattened narrow surface, continuous with the inner surface of

f

Fig. 3B.

Fig. 88. The same cast as exhibited in fig. 3a, seen from below. The right
lateral ventricle is larger than the left. Both posterior horns, p./., are
directed backwards, with a very slight inclination outwards on the right
side.--On the under surface of the right inferior horn the depression for
the hippocampus major, h.m,., is seen, ending anteriorly in the pes.
External to this depression is seen the pes accessorius, ending posteriorly
in the trigonum ventriculi, ¢.v. The calear avis, c.f, is large on the right
side, small on the left. Both posterior cornua are notched.

the anterior cornu, and corresponding to the posterior end of
the dilated septum lucidum (fig. 4).

Posteriorly, the body of the lateral ventricle gives off the
posterior and the inferior cornua. The shape of the posterior
cornua, which, like anterior, are usually shorter than the inferior,

Pa a es CC

* i ee

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 163

is variable, and not so readily described in words as represented
in a sketch or model. When much dilated, the posterior cornua
may be directed inwards posteriorly, so as to be convex outwards
(figs. 2A, 2B). The posterior horns, at their junction with the

{/,
/
ul ] j
A i-

“Cty - = TE

Fig. 4.

Fig. 4. Cast of the third and right lateral ventricles of the cerebrum, seen from
the left side, Case 4. Female, aged 55 years, suffering from general
paralysis of the insane. The lateral ventricle is the largest of the series.
The third ventricle remains relatively small, its form and direction diverging,
nevertheless, more from the normal than any of the preceding. The mesial
surface of the lateral ventricle, m.s., is seen, corresponding to the septum
lucidum, which has undergone an increase in size. The right lateral
ventricle (which is larger than its fellow) exhibits towards the root of the
posterior cornu a grooved surface, f.m., corresponding to the forceps major
of the splenium of the corpus callosum. The posterior cornu. p.h., which
curves inwards at its extremity, exhibits a groove corresponding to the
calear avis, c.f., below which is the trigonum. On the upper surface of the
inferior horn is a deep groove, ch.p., for the choroid plexus. Below, and in
part internal to this, is the groove for the hippocampus major, h.m., external
to which is another parallel groove on the under surface of the inferior horn
for the pes accessorius or eminentia collateralis.

bodies of the lateral ventricle, present on their inner aspect
several deep grooves, separated by well marked ridges (figs. 1a,
3a, 3B), corresponding to the forceps major of the corpus

164 DR J. O. WAKELIN BARRATT.

callosum (fm., fig. 4). The posterior cornua are sometimes
sessile, sometimes prolonged into prominent tips (figs. 24, 2B, 4) ;
they may be notched posteriorly, the notch corresponding to the
groove for the anterior end of the calcarine fissure. On the
outer aspect of the posterior cornu, at its junction with the body,
one or two large flat grooves are sometimes seen; it is doubtful
if these stand in relation to the convolutions on the outer
surface of the hemisphere. The upper border of the posterior
horn is broad. Below is seen the triangular area corresponding
to the trigonum ventriculi, ¢.v. (figs. 2A, 3B, 4). On the anterior
aspect of the junction of posterior horn with the body and
inferior horn is a surface, flattened from side to side and concave
from above downwards, corresponding to the pulvinar of the
optic thalamus ; this surface is deeply grooved for the choroid
plexus.

The inferior cornua, whose general form has been already
described, exhibit on the upper surface, close to the inner border,
a deep groove, ch.p., formed by the choroid plexus of the lateral
ventricle, continuous with that seen on the under surface of the
body of this ventricle, and stopping short of the tip of the
inferior horn. The under surface of the inferior horn always
shows towards its inner border a deep groove, corresponding to
the hippocampus major, terminating anteriorly in a well formed
foot, representing the cornu ammonis (fig. 3B). The under
surface is limited on its outer aspect by a ridge, external. to
which is a surface, usually narrow, corresponding to the collateral
eminence (fig. 4), continuous posteriorly with the triangular
depression representing the trigonum ventriculi, tv. The upper
surface of the inferior cornu is smooth, and convex from side
to side, and also from before backwards; its outer border may
be grooved if the dilatation of the ventricles is considerable,
and the grooves are in that case traceable to the sulci separating
the temporal gyri.

The following table shows in four of the cases examined the
capacity of the ventricular cavity of the cerebrum, and its
relation to the atrophied brain in each case.

TABLE]

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 165

Capacity of 4 :
Case, | Mental state.|Age. Sex, ight; roof 8rd bib of Brain :
] wantvitles, rain, ventricles.
1 | Dementia, 68 | M. 33 ¢c.c. 1165 g. 100: 2°8
2 ae 69 M. 62 ,, 1230 ,, 100: 5°0
mol ts, Fh, 51) M. 74,, 1380 ,, 100: 5°4
+ os 55 | F. 157 ,, 1060 ,, 100 : 13°3

The last column was obtained by dividing the weight of the
whole brain plus that of the brain substance corresponding to
the ventricular cavity, by the weight of brain substance corre-
sponding to the ventricular cavity, the latter being obtained by
multiplying the capacity of the lateral and third ventricles in
eubie centimetres by the specific gravity of the brain (1°038).
In Case 1, the brain was not considerably atrophied, nor were
the ventricles largely dilated, while in the remaining cases the
brain atrophy and ventricular dilatation progressively increased.
The actual percentage of brain-wasting is less than that given
in the last column, particularly in Case 4, because the original
weight of the brain (ie. before wasting commenced) is higher
than that taken by an amount of brain substance equal to the
amount of fluid in the sub-arachnoid space, the amount of which
could not be determined.

The general appearance of the lateral ventricles of the cerebrum
when dilated shows that the enlargement is due essentially to
wasting of white matter. This wasting is exceedingly well
seen in the inferior cornua, where, when the wasting is consider-
able, the bases of several of the temporal sulci (in one case of
all) may be represented by grooves on the cast, while the inter-
vening gyri are represented by ridges. On the other hand, the
third ventricle, which is bounded by grey matter, is but little
dilated as compared with the lateral ventricles. The frontal
and parietal gyri, however, are not represented on the surface of
the casts, the depth of white matter being here considerably
thicker than in the temporal lobes. The grooving of the upper
surface of the bodies of the lateral ventricles must be attributed
to wasting of the nerve bundles of the corpus callosum, and
indicates that this structure wastes unequally. The wasting

166 DR J. O. WAKELIN BARRATT.

of the white matter, when marked, is strikingly shown, especially
in the temporal lobes, in a series of frontal sections.

The number of cases studied is too small to permit of a
comparison of the form of the ventricular cavity in different
cases of brain atrophy. It may, however, be observed that in
the four cases of senile atrophy (two of which are represented
in figs. 1 and 2), the cerebral ventricular cavities, though
differing in size from those observed in the two cases of general
paralysis (figs. 3 and 4), do not otherwise exhibit any peculiarities
of form sufficiently marked to permit any definite distinction to
be drawn between the two classes of cases.

In conclusion, the following points relating to the general
form of the cerebral ventricular cavity in chronic brain atrophy
may be again enumerated. It must be borne in mind that
they are not stated as general assertions, applicable to all cases,
but merely represent the facts observed in the six cases actually
studied.

1. The increase in size of the third ventricle was found to be
small as compared with that of the lateral ventricles.

2. The enlargement of the ventricular cavity of the cerebrum
is almost wholly due to dilatation of the lateral ventricles, which
are everywhere enlarged. The enlargement, however, affects the
anterior cornua and bodies more than the rest of the ventricular
cavity, while the inferior cornua are often much flattened.

3. The appearance of the ventricular cavity in senile atrophy
(four cases) was not observed to differ markedly in its general
characters from that present in general paralysis of the insane
(two cases).

4. The dilatation is chiefly due to wasting of the white matter
of the brain mantle. .

sd

TABLE OF REFERENCE LETTERS.

a.c. groove for the anterior white commissure.

a.h. anterior cornu.

aq. upper end of the aqueduct of Sylvius,

c.f. depression for the calcar avis.

ch. groove for the optic chiasma.
ch.p. deep groove for the choroid plexus of the lateral ventricle.
Jf.m. grooved surface corresponding to the forceps major.

REBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 167

. depression corresponding to the hippocampus major.

t. the cavity of the infundibulum. ‘
oramen or canal for the middle grey commissure.

‘mesial surface of the lateral ventricle.

ession for the caudate nucleus.

groove for the posterior white commissure.

sterior cornu.

concave surface corresponding to that portion of the optic
_ thalamus which projects into the lateral ventricle.
trigonum ventriculi.

ON THE ORIGIN OF VERTEBRATES DEDUCED FROM
THE STUDY OF AMMOCCETES. By Watrer H.
GasKELL, M.D., LL.D., F.RS., University Lecturer on
Physiology ; Fellow of .Trinity Hall.

Part XI.—THE ORIGIN OF THE VERTEBRATE Bopy Cavity AND
EXCRETORY ORGANS; THE MEANING OF THE SOMITES OF
THE TRUNK AND OF THE DUCTLESS GLANDS.

In this series of papers I have considered up to the present the
cranial region as a system of segments, and shown how such
segments are comparable one by one with the corresponding
segments in the prosoma and mesosoma of the presumed arthro-
pod ancestor.

In the spinal region such direct comparison is not possible,
as is evident on the face of it; for even among vertebrates them-
selves the spinal segments are not comparable one by one, so
great is the variation, so unsettled is the number of segments
in this region. This meristic variation, as Bateson calls it, is
the great distinctive character of the spinal region, which dis-
tinguishes it from the cranial region with its fixed number of
nerves and its substantive rather than meristic variation.
At the borderland between the two regions we see how the one
type merges into the other; how difficult it is to fix the seg-
mental position of the spino-occipital nerves; how much more
variable in number are the segments supplied by the vagus
nerves than those anterior to them.

This meristic variation is a sign of instability, of want of -
fixedness in the type, and is evidence, as already pointed out,
that the spinal region is newer than the cranial.

This instability in the number of spinal segments does not
necessarily imply a variability in the number of segments of
the metasoma of the invertebrate ancestor; it may simply be
an expression of adaptability in the vertebrate phylum itself,
according to the requirements necessitated by the conversion
of a crawling into a swimming animal, and the subsequent con-
version of the swimming into a terrestrial or flying animal.

a a TF a a

0 ie

ORIGIN OF VERTEBRATES. 169

However many may have been the original number of seg-
ments belonging to the spinal region, one thing is certain—the
segmental character of this region is remarkably clearly shown,
not only by the presence of the segmental spinal nerves, but
also by the marked segmentation of the mesoblastic structures.

The question therefore that requires elucidation above all
others is the origin of the spinal mesoblastic segments, 7.¢. of the .
ecelomic cavities of the trunk region, and the structures derived
from their walls. |

The Origin of the Pronephros, Mesonephros and Body Cavity.

The nature of the primitive trunk segment is conveniently
expressed by using v. Wijhe’s' phraseology. He terms the
whole ccelomic cavity the procelom, which is divisible into a
ventral unsegmented part, the body cavity or metacelom, and a
dorsal segmented part, the somite. This latter part again is
divided into a dorsal part, the epimer, and a part connecting the

_ dorsal part with the body cavity, to which therefore he gives

the name of mesomer.

The cavity of the epimer disappears, and its walls form the
muscle and cutis plates of the body. The part which forms the
muscles is known as the myotome, which separates off from the
mesomer, leaving the latter as a blind sac, the mesocwlom, com-
municating by a narrow passage with the body cavity or meta-
cwlom. At the same time from the mesomer is formed the
sclerotome, which gives rise to the skeletal tissues of the vertebre,
ete., so that v. Wijhe’s epimer and mesomer together correspond
to the original term protovertebra or somite of Balfour; and
when the myotome and sclerotome have separated off, there is still
left the intermediate cell mass of Balfour and Sedgwick, 7c. the
sac-like mesoccele of v. Wijhe, the walls of which give origin to
the mesonephrotome or mesonephros. Further, according to v.
Wijhe, the dorsal part of the unsegmented metaccelom is itself
segmented, but not, as in the case of the mesoceele, with respect
to both splanchnopleuric and somatopleuric walls. The seg-
mentation is manifest only on the somatopleuric side, and

1 “ Ueber die Mesoderm segmente des Rumpfes u, die Entwick. des Excretion-

systems bie Selachiern,” von v.. Wijhe, Arch. f. Mikr. Anat., Bd. xxxiii. p.
461, 1889.

170 DR WALTER H. GASKELL.

consists of a distinct series of hollow somatopleuric outgrowths,
called by him hypomeres, which give rise to the pronephros and
the segmental duct.

V. Wijhe considers that the whole metaccelom was originally
segmented, because in the lower vertebrates the segmentation
reaches further ventralwards, so that in Selachians the body
cavity is almost truly segmental. Also in the gill region of
Amphioxus the cavities which are homologous with the body
cavity arise segmentally.

It is quite unnecessary to trace the history of our knowledge
of the development of the excretory vertebrate organs, for it
has been admirably done by Riickert! up to 1891. I shall
therefore refer my reader to that paper, and here only sketch
the rise and fall of opinion upon the phylogenetic meaning of
such investigations.

As is well known, Balfour and Semper were led, from their
embryological researches, to compare the nephric organs of
vertebrates with those of annelids, and indeed the nature of
the vertebrate segmental excretory organs has always been
the fact which has kept alive the belief in the origin of verte-
brates from a segmental annelid. These segmental organs thus.
compared were the mesonephric tubules, and doubts arose, espe-
cially in the mind of Gegenbaur, as to the validity of such a
comparison, because the mesonephric tubules did not open to
the exterior, but into a duct, the segmental duct, which was an un-
segmented structure opening into the cloaca; also because the
segmental duct, which was the excretory duct of the pronephros,
was formed first, and the mesonephric tubules only opened into
it after it was fully formed. Further, the pronephros was said
to arise from an outbulging of the somatopleuric mesoblast,
which extended over a limited number of metameres, and was
not segmental, but continuous. Gegenbaur and others therefore
argued that the original prevertebrate excretory organ was
the pronephros and its duct, not the mesonephros, from which
they concluded that the vertebrate must have been derived
from an unsegmented type of animal, and not from the segmented
annelid type. Such a view, however, has no further reason for

‘,“« Entwicklung d. Exkretionsorgane,” von J. Riickert, Anatom. Hefte Merkel,
u. Bonnett, Bd. i., 1891, p. 606.

ORIGIN OF VERTEBRATES. 171

acceptance, as it was based on wrong premises, for Riickert has
shown that the pronephros does arise as a series of segmental
nephric tubules, and is not unsegmented ; he also has pointed
out that in Torpedo the anterior part of the pronephric duct
shows indications of being segmented; a statement fully borne
out by the researches of Maas! on Myxine, who gives the
clearest evidence that in this animal the anterior part of the
pronephric duct is formed by the fusion of a series of separate

ducts, each of which in all probability once opened out separately

to the exterior.

Riickert therefore concludes that Balfour and Semper were
right in deriving the segmental organs of vertebrates from
those of annelids, but that the annelid organs are represented
in the vertebrate, not by the mesonephric tubules, but by the
pronephric tubules and their ducts, which originally opened
separately to the exterior. By the fusion of such tubules the
anterior part of the segmental duct was formed, while its
posterior part was brought about either by a later coenogenetic
lengthening, or is the only remnant of a series of pronephric
tubules which originally extended the whole length of the
body, as suggested also by Maas and Boveri. Riickert therefore
supposed that the mesonephric tubules were a secondary set
of nephric organs, which were not necessarily directly derived
from the annelid nephric organs.

V. Wijhe, in his original paper,? did not consider that it was
possible to derive any of the vertebrate excretory organs from
an invertebrate type, because they were not represented in
Amphioxus, and therefore arose after the chordate type of animal
had arisen; in any case, he agreed with Riickert that the
mesonephric tubules were not homologous with the nephric
tubules of the annelid, and did not think that Riickert’s
suggestion that the pronephros is homologous with the annelid
nephric organs was likely to find general acceptance until the
differences between annelids and vertebrates in other respects—
such as the central nervous system of the former with its
cesophageal ring—are satisfactorily explained.

1 “Ueber Entwick, stadien d. Vorniere u. Urniere bei Myxine,” von O, Maas,
Zool. Jahriuch, Ba. x., 1897, p. 473.
2 Op. cit., p. 511.

172 DR WALTER H. GASKELL.

The discovery of the nephric tubules of Amphioxus by Boveri +
and Weiss? has removed v. Wijhe’s difficulty, and has still
further confirmed Riickert’s suggestion, for Boveri looks upon
these organs as pronephric although they are confined to the
branchial region, and considers that the pronephric organs
originally extended along the whole trunk region, because he
considers that the branchiz also extended along the whole length
of the body.

With respect to his further remark about the need of a
satisfactory explanation of the differences between the annelid
and vertebrate nervous systems, before Riickert’s suggestion is
likely to find general acceptance, I venture to hope that the
explanation I have given in this series of papers will prove
satisfactory to him,

At present, then, Riickert’s view is the most generally accepted
one :—that the original annelid nephric organs are represented
by the pronephric tubules and the pronephric duct, not by the
mesonephric tubules, which are a later formation.

This latter statement would hold good if the mesonephric
tubules were found entirely in segments posterior to those
containing the pronephric tubules; such, however, is said not
to be the case, for the two sets of organs are said to overlap
in some cases; even when they exist in the same segments the
former are said always to be formed from a more dorsal part of
the ccelom than the pronephros, always to be a later formation,
and never to give any indication of communicating with the
exterior except by way of the pronephric duct.

The recent observations of Brauer*® on the excretory organs
of the Gymnophiona throw great doubt on the existence of
mesonephric and pronephric tubules in the same segment.
He criticises the observations on which such statements are
based, and concludes that, as in Hypogeophis, the nephrotome
which is cut off after the separation of the sclero-myotome gives

**Die Nieren Canilchen des Amphioxus,” von Th. Boveri, Zool. Jahrbuch,
Bd. v., 1892, p. 429.
> «* Excretory tubules in Amphioxus lanceolatus,” by F. E. Weiss, Q. J. Mier.
Sci., vol. xxxi., 1890.

* “ Beitriig. z. Kenntniss d. Entwick. u. Anat. d. Gymnophionen.”—III.
“Die Entwicklung d. Exeretionsorgane,” von A. Brauer, Zool. Jahrbuch,
Bd. 16, p. 1, 1902,

ORIGIN OF VERTEBRATES. 173

origin te the pronephros in the more anterior regions, just as it
gives origin to the mesonephros in the more posterior regions.
In fact, the observations of v. Wijhe and others do not in
reality show that two excretory organs may be formed in one
segment, the one mesonephric from the remains of the mesomer
and the other pronephric from the hypomer, but rather that in
such cases there is only one organ,—the pronephros,—part of
which is formed from the mesomer and part from the hypomer.
Brauer goes further than this, and doubts the validity of any
distinction between pronephros and mesonephros, on the ground
of the former arising from a more ventral part of the proccelom

_ than the latter; for, as he says, it is only possible to speak of

one part of the somite as being more ventral than another part
when both parts are in the same segment; so that if pronephric
and mesonephric organs are never in the same segment, we
cannot tell with certainty that the former arises more ventrally
than the latter.

These observations of Brauer strongly confirm Sedgwick’s
original statement that the pronephric and mesonephric organs
are homodynamous organs, in that they are both derived from
the original serially situated nephric organs, the differences
between them being of a subordinate nature, and not sufficient
to force us to believe that the mesonephros is an organ of quite
different origin to the pronephros.

So also Price, from his investigations of the excretory organs
of Bdellostoma, considers that in this animal both pronephros
and mesonephros are derived from a common embryonic kidney,
to which he gives the name ‘ holonephros.’

Brauer also is among those who conclude that the vertebrate
excretory organs were derived from those of annelids ; he thinks
that the original ancestor possessed a series of similar organs
over the whole pronephric and mesonephric regions, and that
the anterior pronephric organs, which alone form the segmental
duct, became modified for a larval existence,—that their
peculiarities were adaptive rather than ancestral.

This view seems to me very far-fetched, without any sufficient
grounds for it; according to the much more probable and

1 ‘* Development of the excretory organs of Bdellostoma Stouti,” by G. C. Price,
Zool. Jahrbuch, vol. x. p. 205, 1897.

174 DR WALTER H. GASKELL,

reasonable view, the pronephros represents the oldest and
original excretory organs, while the mesonephros are later
formations. Brauer’s evidence seems to me to signify that
the pronephros, mesonephros and metanephros are all serially
homologous, and the pronephros bears much the same relation
to the mesonephros that the mesonephros does to the:
metanephros. The great distinction of the pronephros is that
it, and it alone, forms the segmental duct.

We may sum up the conclusions as follows :—

1. The pronephrie tubules and the pronephrie duct are the
oldest part of the excretory system, and are distinctly in
evidence for a few segments only in the most anterior part of
the trunk region immediately following the branchial region.
They differ also from the mesonephric tubules by not being so
clearly segmental with the myotomes,

2. The mesonephric tubules belong to segments posterior to
those of the pronephros, are strictly segmental with the
myotomes, and open into the pronephric duct.

3, All observers are agreed that the two sets of excretory
organs resemble each other in very many respects, as, though
they arose from the same series of primitive organs, and accord-
ing to Sedgwick and Brauer, no distinction of any importance
does exist between the two sets of organs. Other observers,
however, consider that the pronephric organs, in part at all
events, arise from a part of the nephroccele more ventral than
that which gives origin to the mesonephric organs, and that this
difference in ‘position of origin, combined with the formation of
the segmental duct, does constitute a true morphological distine-
tion between the two sets of organs.

4. All the recent observers are in agreement that the
vertebrate excretory organs strongly indicate a derivation from
the segmental organs of annelids.

The very strongest support has been given to this last con-
clusion by the recent discoveries of Boveri! and Goodrich? upon
the excretory organs of Amphioxus. According to Boveri, the
nephric tubules of Amphioxus open into the dorsal ccelom by

1 Op, cit, :

9

2 «Qn the structure of the excretory organs of Amphioxus,” by E. S. Good-
rich, Q. J. Micr. Sci., vol. 45, p, 498, 1902.

ORIGIN OF VERTEBRATES, 175

one or more funnels. Around each funnel are situated groups

of peculiar cells, called by him ‘Fadenzellen,’ each of which
sends a long process across the opening of the funnel. Goodrich
has examined these Fadenzellen and found that they are typical
pipe cells or solenocytes, such as he has described! in the
nephridial organs of various Polychetes. Also, just as in the
Polycheetes, the ciliated nephric tubule has no internal funnel-
shaped opening into the ccelom, but terminates in these groups
of solenocytes. “Each solenocyte® consists of a cell body and
nucleus situated at the distal free extremity of a delicate tube;
the proximal end of the tube pierces the wall of the nephridial
canal and opens into its lumen. A single long flagellum arising
from the cells works in the tube and projects into the canal.”

The exceedingly close resemblance between the organs of
Amphioxus and those of Phyllodoce, as given in his paper, is most
striking, and, as he says, forces the conclusion that the excretory
organs of Amphioxus are essentially identical with the nephridia
of certain polychete worms.

It is to me most interesting to find that the very group of
annelids, the Polychzta, which possess solenocytes so remarkably
resembling those of the excretory organs of Amphioxus, are the
highest and most developed of all the Annelida. My contention
has been throughout, that the Protostraca, from which the three
groups of Crustacea, Arachnida and Vertebrata are supposed to
have arisen, must have been closely allied to the highest group of
annelids, the Chetopoda, and not to any lower group ; the evidence
of Amphioxus suggests strongly that the protostracan ancestor
of the vertebrates arose from the highest group of the Cheetopods,
viz., the Polycheta.

The evidence which I have given in my former papers of this
series points, however, strongly to the conclusion that the
vertebrate did not arise from members of the Protostraca near
to the polychete stock but rather from members in which the
arthropod characters had already become well developed;
members, therefore, which were nearer the Trilobites than the

1 “©On the nephridia of the Polycheta,” parts i., ii., iii, Q. J. Mier. Sei.,
vols. 40, 41, 43,

2 On the excretory organs of Amphioxus,” by E, 8S, Goodrich, Proc. Roy.
Soe., vol. Ixix. p. 351, 1902,

176 DR WALTER H. GASKELL.

Polychetes. Such early arthropods would very probably have
retained in part excretory organs of the same character as those
found in the original polychete stock, and thus account for the
presence of solenocytes in the excretory organs of Amphioxus.

In connection with such a possibility I should like to draw
attention to the observations of Claus! and Spangenberg? on the
excretory organs of Branchipus—that primitive phyllopod, which
is recognised as the nearest approach to the trilobites at present
living.

According to Claus, an excretory apparatus exists in the
neighbourhood of each ganglion, and Spangenberg finds a perfectly
similar organ in the basal segment of each appendage; a system,
therefore, of excretory organs as segmentally arranged as those of
Peripatus. Claus considered that although these organs formed
an excretory system, it was not possible to compare them with
the annelid segmental organs, because he shove the cells in
question arose from ectoderm.

Now, the striking point in the description of the excretory
cells in these organs, as described both by Claus and Spangenberg,?
is that they closely resemble the pipe cells or solenocytes of
Goodrich ; each cell possessed a long tube-like projection, which
opens on the surface. . They appear distinctly to belong to the
category of flame cells, and resemble solenocytes more than any-
thing else.

According to Goodrich, the solenocyte is probably an ecto-
dermal cell, so that even if it prove to be the case, as Claus
thought, that these pipe cells of Branchipus are ectodermal,
they would still claim to be derived from the segmental
organs of annelids, especially of the Polycheta, being, to use
Goodrich’s nomenclature, true nephridial organs, as opposed
to ccelomostomes.

I cannot find in the later literature of the subject any in-
vestigations on these excretory organs; in view of the great
importance of this question, I venture to hope that the discoverer
of the solenocyte will, in the course of his further researches,

* “ Untersuch, iib. d. Organism. u. Entwick. v. Branchipus u. Artemia,”
von Claus, Arbeit. a. d. Zool. Instit., Wien, Bd. 6, p. 267, 1886.

? Spangenberg, Zeitschr, f. wissent, Zool,, Bd. 25, 2, 1875.

3 Cf. op. cit., fig. 6, taf. 1. p

Pore eh ee ane ee

ORIGIN OF VERTEBRATES. 177

take into consideration these organs of Branchipus, and let us
know whether they are of the nature of solenocytes or not.

These observations of Claus and Spangenberg suggest not
only that the primitive arthropod of the trilobite type possessed
segmental organs in every segment directly derived from those
of a polychete ancestor, but also that such organs were partly
‘somatic and partly appendicular in position. Such a suggestion
is in strict accord with the observations of Sedgwick! on the
excretory organs of the most primitive arthropod known, viz.,
Peripatus, where also the excretory organs which are true
‘segmental organs are partly somatic and partly appendicular.
Further; the excretory organs of the Scorpion and Limulus group
are again partly somatic and partly appendicular, receiving the
name of coxal glands because there is a ventral projection of the
gland into the coxa of the corresponding appendage.

Judging from all the evidence available, it is probable that
when the arthropod stock arose from the annelids, simultaneously
with the formation of appendages, the segmental somatic nephric
organs of the latter extended ventrally into the appendage, and
thus formed a segmental set of excretory organs, which were
partly somatic partly appendicular in position, and might there-
fore be called coxal glands.

Further, the evidence of Miss Sheldon? in Peripatus shows
that such a diverticulum of the original nephrocele into the
appendage, as would naturally be expected, is formed from the
somatopleuric layer alone, just as has been stated to be the case
in the formation of at all events a portion of the pronephric
organ in the vertebrate.

As already stated, all investigators of the origin of the vertebrate
excretory organs are unanimous in considering them to be derived
from segmental organs of the annelid type. I naturally agree
with them, but, in accordance with my theory, would substitute
the words‘ primitive arthropod’ for the word ‘ annelid,’ for all the
evidence I have accumulated in the preceding papers of this
series points directly to that conclusion. Further, the most

1 ** 4 monograph of the development of Peripatus Capensis,” by A. Sedgwick,
Studies from the Morphol. Lab., Cambridge, vol. iv. pt. 1, 1888.

2 **On the development of Peripatus Nova-Zealandia,” by L. Sheldon, Studies
from the Morphol, Lab., Cambridge, vol. iv. pt. 3, 1889, pl. xxvi. fig. 210,

VOL, XXXVII. (N.S. VOL. XVII.) —JAN. 1903, 12

178 DR WALTER H. GASKELL.

primitive of the three sets of vertebrate segmental organs—the
pronephros, mesonephros and metanephros—is undoubtedly the
pronephros ; consequently the pronephric tubules are those which
I consider to be more directly derived from the coxal glands of
the primitive arthropod ancestor. Such a derivation appears to:
me to afford an explanation of the difficulties connected with the
origin of the pronephros and mesonephros respectively, which is.
more satisfactory than that given by the direct derivation from
the annelid.

The only living animal which we know of as at all ap-
proaching the most primitive arthropod type is, as pointed
out by Korschelt and Heider, Peripatus; and Peripatus, as is-
well known, possesses a true ceelom and true ccelomic excretory
organs in all the segments of the body.

Sedgwick shows that at first a true ccelom, as good as that of the:
annelids, is formed in each segment of the body, and that then
this coelom (which represents in the vertebrate v. Wijhe’s pro-
ccelom) splits into a dorsal and a ventral part. In the anterior
segments of the body the dorsal part disappears (presumably its.
walls give origin to the mesoblast from which the dorsal body
muscles arise), while the ventral part remains and forms a
nephroceele, giving origin to the excretory organs of the adult.

According to v. Kennel, the cavity becomes divided into three:
spaces, which for a time are in communication—a lateral (1.), a.
median (II.), and a dorso-median (III.). The dorso-median
portion becomes partitioned off, and this, as well as the greater
part of the lateral portion, which lies principally in the foot, is:
used up in providing elements for the formation of the body
and appendage muscles respectively and the connective tissue.

In fig. 1, I reproduce v. Kennel’s diagram of a section across
a Peripatus embryo, in which I. represents the lateral appendicular
part of the celom, IL the ventral somatic part, and III. the
dorsal part which separates from the ventral and lateral parts,
and, as its walls give origin largely to the body muscles, may be
called the myocele. The muscles of the appendages are formed
from the ventral part of the original proccelom, just as I have
argued is the case with the muscles of the splanchnic segmenta-
tion in vertebrates. Sedgwick states that the ventral part of
the cceelom extends into the base of each appendage, and there:

ORIGIN OF VERTEBRATES. 179

forms the end sac of each nephric tubule, into which the nephric
funnel opens, thus forming a coxal gland; this end sac or
vesicle in the appendage is called by him the internal vesicle
(7.v.), because later another vesicle is formed from the ventral
eeelom in the body itself, close against the nerve cord on each
side, which he calls the external vesicle (¢.v.). (Cf. fig. 2, taken
from Sedgwick.) This second vesicle is, according to him,

Fic. 1.—Transverse section of Peripatus embryo (after v. Kennel). A/., ali-
mentary canal; W., nerve cord; App., appendage; J, JJ, III, the three
divisions (lateral, median, and dorso-median) of the ccelom.

Fic. 2.—Section of Peripatus (after Sedgwick), AJ., alimentary canal ; J, nerve
cord ; App., appendage; i.v., internal, and ¢.v., external vesicles of the
segmented excretory tubule (coxal gland).

formed later in the development from the nephric tubule of the
internal vesicle, so that it discharges its contents to the exterior
by the same opening as the original tubule. Of course, as he
points out, the whole system of internal and external vesicles
and nephric tubules are all simply derivatives of the original
ventral part of the ccelom or nephroccele.

Here, then, in Peripatus, and presumably therefore in members

180 DR WALTER H. GASKELL.

of the Protostraca, we see that the original segmental organs of
the annelid have become a series of nephric organs, which ex-
tended into the base of the appendages, and may therefore be
called coxal glands; also it is clear from Sedgwick’s description
that if the appendages disappeared, the nephric organs would
still remain, not as coxal glands, but as purely somatic excretory
glands. They would still be homologous with the annelid
segmental organs or with the coxal glands, but would arise im
toto from a part of the ventral ccelom or nephroceele more dorsal
than the former appendicular part, because the appendages and
their enclosed ccelom are always situated ventrally to the body.
Again, according to Sedgwick, the nephric tubules are connected
with two cclomic vesicles, the one in the appendage, the
internal vesicle, and the other, the so-called bladder, or the
external vesicle in the body itself, close against the nerve cord.
Sedgwick appears to consider that either of these vesicles may
form the end sac of a nephric tubule, for he discussest the
question whether the single vesicle which in each case gives
origin to the nephridia of the first three legs corresponds to the
internal or external vesicle. He decides, it is true, in favour of
the internal vesicle, and therefore considers the excretory organ
to be appendicular, 7.e. a coxal gland, in these segments as well
as in those more posterior; still the very discussion shows that
in his opinion at all events the external vesicle might represent
the end. sac of the tubule, in the absence of the internal or
appendicular vesicle.

Such an arrangement as Sedgwick describes in Peripatus is
the very condition required to give rise to the pronephric and
mesonephric tubules, as deduced by me from the consideration
of the vertebrate, and harmonises and clears up the controversy
about the mesonephros and pronephros in the most satisfactory
manner.

Both pronephros and mesonephros are seen to be derivatives
of the original annelid segmental organs, not directly from an
annelid, but by way of an arthropodan ancestor; the difference
between the two being simply that the pronephric organs were
coxal glands, and indicate therefore the presence of the original
metasomatic appendages, while the mesonephric organs were

1 Op, cit., p. 140.

ORIGIN OF VERTEBRATES. 181

homologous organs, formed in segments of later origin which
had lost their appendages.

For this reason the pronephros is said to be formed, in part at
least, from a portion of the ccelom situated more ventrally than

the purely somatic part which gives rise to the mesonephros.

For this reason Sedgwick, Brauer, etc. can say that the meso-
nephros is strictly homodynamous with the pronephros; while
equally Riickert, Semon and v. Wijhe can say it is not homo-
dynamous, in so far that the two organs are not derived strictly
from absolutely homologous parts of the ccelom.

For this reason Semon can speak of the mesonephros as a
dorsal derivative of the pronephros, just as Sedgwick says that
the external or somatic vesicle of Peripatus is a derivative of
the appendicular nephric organ. For this reason the pronephros,
or rather a part of it, is always derived from the somatopleuric
layer, for, as is clear from Miss Sheldon’s drawing, the part
of the ccelom in Peripatus which dips into the appendage is
derived from the somatopleuric layer alone.

Such a ccelom as that of Peripatus, fig. 1, would represent the
origin of the vertebrate ccelom, and would therefore represent
the procelom of v. Wijhe; and in accordance we see that it
separates into a dorsal part, the walls of which give origin to
the somatic muscles, or at all events to the great longitudinal
dorsal muscles of the animal, and a ventral part, which forms a
nephroceele, dips into the appendage, and gives origin to the
muscles of the appendage. In the vertebrate, after the somatic
dorsal part or myoccele has separated off, there is left a ventral
part, which forms a nephroceele in the trunk region, and gives
origin to the splanchnic striated muscles in the cranial region,
ie. to the muscles which, according to my theory, were once
appendicular muscles, This ventral nephroceelic part is divisible
in the trunk into a segmented part, which forms the excretory
organs proper, and an unsegmented part, the metaccele or true
body cavity of the vertebrate.

This comparison of the procceelom of the vertebrate and
arthropod signifies that the vertebrate metaccele was directly
derived by ventral downgrowth from the arthropod nephrocele,
so that if, as I suppose, the vertebrate nervous system represents

1 Loe cit,

182 DR WALTER H. GASKELL.

the conjoined nervous system and alimentary canal of the
arthropod, then the vertebrate metaccele, or body cavity, must
lave been originally confined to the region on each side of the
central nervous system, and from this position have spread
ventrally to ultimately enclose the new formed vertebrate gut.
This means that the body cavity (metaccele) of the vertebrate is
not the same as the body cavity of the annelid, but corresponds
to a ventral extension of the nephrocele, or ventral part of
such body cavity.

Such a phylogenetic history is most probable, because it
explains most naturally and simply the facts of the development
of the vertebrate body cavity; for the mesoblast always
originates in the neighbourhood of the notochord and central
nervous system, and the lumen of the body cavity always
appears first in that region, and then extends laterally and
ventrally on each side until it reaches the most ventral surface of
the embryo, thus forming a ventral mesentery, which ultimately
disappears, and the body cavity surrounds the gut, except for
the dorsal mesentery. Thus Shipley! in his description of the
formation of the mesoblastic plates which line the body cavity
in Ammoccetes describes them as commencing in two bands
of mesoblast situated on each side, close against the commencing
nervous system: “these two bands? are separated dorsally by
the juxtaposition of the dorsal wall of the mesenteron and the
epiblast, and ventrally by the hypoblastic yolk-cells which are
in contact with the epiblast over two-thirds of the embryo.
Subsequently, but at a much later date, the mesoblast is
completed ventrally by the downgrowth on each side of these
mesoblastic plates. The subsequent downward growth is
brought about by the cells proliferating along the free ventral
edge of the mesoblast; these cells then growing ventralwards,
pushing their way between the yolk-cells and epiblast.”

The derivation of the vertebrate pronephric segmental
organs from the metasomatic coxal glands of a primitive
arthropod would mean, if the segmental organs of Peripatus be
taken as the type, that such glands opened to the exterior on

* “On some points in the development of Petromyzon fluviatilis,” by A. E.
Shipley, Q. J. Mier. Sci., 1887.
2 Op. cit., pp. 5 and 6, fig. 16.

ORIGIN OF VERTEBRATES. 183

every segment, either at the base of the appendage or on the

appendage itself.

It is taken for granted by most observers that the pronephric

_ segmental organs once opened to the exterior on each segment,

and then, from some cause or other, ceased to do so, and the
‘separate ducts, by a process of fusion, came to form a single
segmental duct, which opened into the cloaca. Many observers
have been led to the conclusion that the pronephric duct is
-epiblastic in origin, although, from its position in the adult,
it appears far removed from all epiblastic formations. How-
-ever, at no time in the developmental history is there any
clear evidence of actual fusion of any part of the pronephric
organ with the epidermis, and the latest observer, Brauer, is
strongly of opinion that there is never sufficiently close contact
with the epidermis to warrant the statement that the epiblastic
cells take part in the formation of the duct. All that can be
‘said is, that the formation of the duct takes place at a time
when the pronephric diverticulum is in close propinquity to the
epidermis, before the ventral downgrowth of the myotome has
taken place.

The formation of the anterior portion of the pronephric
-duct is, according to Maas! in Myxine, and Wheeler? in
Petromyzon, undoubtedly formed by the fusion of a number
of pronephric tubules, which, according to Maas, are

clearly seen in the youngest specimens as separate seg-

mental tubes; each of these tubules is supplied by a

capillary network from a segmental branch of the aorta, as

in the tubules of Amphioxus according to Boveri, and does
not possess a glomerulus. :

The posterior part of the duct into which the mesonephric
tubules enter possesses also a capillary network, which Maas

-considers to represent the original capillary network of a series

of pronephric tubules, the only remnant of which is the duct
into which the mesonephric tubule opens. He therefore argues
that the pronephric duct indicates a series of pronephric tubules,
which originally extended along the whole length of the body,

1 Op. cit.
2 “ Development of the urinogenital organs of the Lamprey,” by Wheeler,
Zool, Jahrbuch, Ba. xiii. p. 1, 1899.

184 DR WALTER H, GASKELL,

and were supplanted by the mesonephric tubules, which also
belonged to the same segments.

I also think that the paired appendages, which have left
as signs of their past existence the pronephric tubules, originally
in the invertebrate stage existed on every segment of the body,
but I do not consider that such a statement is at all equivalent
to saying that such pairs of tubules must have existed upon
every one of the segments existing at the present day; for it.
seems to me that Riickert is much more likely to be right when
he says that in Selachians the duct clearly does grow back,
and is not formed throughout in situ; so that he gives a double
explanation of the formation of the duct: a palingenetic.
anterior part formed by the fusion of the extremities of the
original excretory tubules, to which a posterior coenogenetic
lengthening has been added.

It does not seem to me at all necessary that the immediate
invertebrate ancestor of the vertebrate should have possessed
excretory organs which opened out separately to the exterior
on each segment; already, in the invertebrate stage, a fusion.
may have taken place, and so a single duct have been acquired
for a number of organs. Such a suggestion has been made by
Riickert,! because of the fact discovered by Cunningham and
E. Meyer that the segmental organs of Lanice conchilega are
on each side connected together by a single strong longitudinal
canal. I would, however, go further than this, and say that,.
even although the nephric organs of the polychete ancestor
opened out on every segment, and although the primitive arthro-
podan ancestor derived from such polychzte possessed coxal
glands which opened out either on or at the base of each
appendage, similarly to those of Peripatus, yet the immediate
arthropodan ancestor, with its paleostracan affinities, may have
already possessed metasomatic coxal glands, all of which opened
into a single duct, with a single opening to the exterior.

Judging from Limulus, such was very probably the case, for
Patten? and Hazen have shown (1). that the coxal glands of
Limulus are segmental organs belonging to the prosomatic

1 <*Ueber die Entstehung der Excretionsorgane bei Selachiern,” von J.
Riickert, Archiv f. Anatomie, 1888, p. 258.

2 «The development of the coxal gland, ete. of Limulus polyphemus,” Journ.
of Morph., vol. xvi. p. 459, 1900. .

se A

——- °

Pane ee | ee |

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ORIGIN OF VERTEBRATES. 185-

segments, (2) that the organs belonging to the cheliceral and

-ectognathic segments are not developed, (3) that the four glands

belonging to the endognaths become connected together by a
stolon, which communicates with a single nephric duct, opening
to the exterior on the basal segment of the 5th prosomatic
appendage (the last endognath). At no time is there any
evidence of any separate openings or any fusion with the
ectoderm such as might indicate separate openings of these
prosomatic coxal segmental organs. |

Thus we see that in Limulus, which is presumably much nearer
the annelid condition than the vertebrate, all evidence of separate
nephric ducts opening to the exterior on each prosomatic
segment has entirely disappeared, just as is the case in the
metasomatic coxal glands (i.e. the pronephros) of the vertebrate.
What is seen in the prosomatic region of Limulus, and doubtless
also of the Eurypterids, may very probably have occurred in the
metasomatic region of the immediate invertebrate ancestors of
the vertebrate, and so account for the single pronephric duct
belonging to a number of pronephric organs.

The interpretation of these various embryological investiga-

_ tions may be summed up as follows :—

1. The ancestor of the vertebrates possessed a pair of
appendages on each segment; into the base of each of these
appendages the segmental excretory organ sent a diverticulum,
thus forming a coxal gland.

2. Such coxal glands, even in the invertebrate stage, may
have discharged into a common duct which opened to the
exterior most posteriorly.

3. Then, from some cause, the appendages were rendered use-
less and dwindled away, leaving only the pronephric organs to
indicate their former presence. At the end of this stage the
animal possessed vertebrate characteristics.

4. For the purpose of increasing mobility, of forming an
efficient swimming instead of a crawling animal, the body
segments increased in number, always, as is invariably the case,
by the formation of new ones between those already formed
and the cloacal region, and so of necessity caused an elongation
of the pronephric duct; into this there opened now the ducts
of the segmental organs formed by recapitulation, those there-

186 DR WALTER H. GASKELL.

fore belonging to the body segments—mesonephric—having
nothing to do with appendages, for these latter had already
ceased to exist functionally, and would not therefore be repeated
with each meristic repetition.

This, so to speak, passive lengthening of the pronephric duct
in consequence of the lengthening of the early vertebrate body
by the addition of metameres, each of which contained only
mesonephric and no pronephric tubules, is to my mind an
example of a principle which has played an important part in
the formation of the vertebrate, viz., that the meristic variation
by which the spinal region of even the lowest of existing verte-
brates has been formed has largely taken place in the vertebrate
phylum itself, and that such changes must be eliminated before
we can picture to ourselves the prevertebrate condition. As an
example, I may mention the remarkable repetition of similar
segments pictured by Bashford Dean! in Bdellostoma, Such
repetition leads to passive lengthening of such parts as are
already formed but are not meristically repeated: such are
the notochord, the vertebrate intestine, the canal of the
spinal cord, and possibly the lateral line nerve. The fuller
discussion of this point means the discussion of the formation
of the vertebrate alimentary canal; I will therefore leave it
until I come to that part of my subject, and only say here that
the evidence seems to me to point to the conclusion that at the
time when the vertebrate was formed, the respiratory and cloacal
regions were very near together, the whole of the metasoma being
represented by the region of the pronephros alone.

Here, as always, the evidence of Ammoccetes tends to give
definiteness to our conceptions, for Wheeler? points out that up
to a length of 7 mm. the pronephros only is formed; there is no
sign of the more posteriorly formed mesonephros. Now we
know, as pointed out in Part VIII. of this series,* this is the time
of Kupffer’s larval stage of Ammoccetes. This is the time during
which the invertebrate stage is indicated in the ontogeny, so
that, in accordance with all that has gone before, this means

1 “On the embryology of Bdellostoma Stouti,” by Bashford Dean, Festschr,
2, siebenzigsten Geburtstag v. C. v. Kupffer, Jena, 1899.

2 Op. cit.

3 This Journ., vol. xxxiv. p. 577.

ORIGIN OF VERTEBRATES. 187

that the metasoma of the invertebrate ancestor was confined to
the region of the pronephros.

Again, take Shipley’s account of the development of
Petromyzon.! He says:

The alimentary canal behind the branchial region may be
divided into three sections. Langerhans has termed these the
stomach, midgut and hindgut, but as the most anterior of these
is the narrowest part of the whole intestine, it would perhaps
be better to call it cesophagus. This part of the alimentary
canal lies entirely in front of the yolk, and is, with the anterior
region which subsequently bears the gills, raised from the rest
of the egg when the head is folded off. It is supported by a
‘dorsal mesentery, on each side of which lies the head kidney
(pronephros).” Further on he says :?

“The hindgut is smaller than the midgut; its anterior limit is
marked by the termination of the spiral valve, which does not
extend into this region. The two segmental ducts open into it
just where it turns ventrally to open to the exterior by a median
ventral anus. Its lumen is from an early stage lined with cells
which have lost their yolk, and it is in wide communication with
the exterior from the first. This condition seems to be, as Scott
suggests, connected with the openings of the ducts of the
pronephros, for this gland is completed and seems capable of
functioning long before any food could find its way through the
midgut, or indeed before the stomodzeum has opened.”

Is there no significance in this statement of Shipley? Even
if it be possible to find some special reason why the branchial
and cloacal parts of the gut are freed from yolk and lined with
serviceable epithelium a long time before the midgut, why should
a bit of the midgut, which Shipley calls the cesophagus, which is
connected with the region of the pronephros, and not of the
branchie, differ so markedly from the rest of the midgut?
Surely the reason is that the branchial region of the gut, the
pronephric region of the gut, and the cloacal region of the gut
belong to a different and earlier phase in the phylogenetic
history of the Ammocctes than the midgut between the
pronephric and cloacal regions. This observation of Shipley fits
in with and emphasises the view that the original animal from

1 Op. cit., p. 26. 2 Op. cit., p. 28.

188 DR WALTER H. GASKELL.

which the vertebrate arose consisted of a cephalic and branchial
region, followed by a pronephric and cloacal region; the whole
intermediate part of the gut, which forms the midgut, with its-
large lumen and spiral valve, and which belongs to the meso-
nephric region, being a later formation brought about by the
necessity of increasing the length of the body.

The Origin of the Somatie Trunk Musculature and the Formation
of an Atrial Cavity.

Next comes the question, why was the pronephros not repeated
in the meristic repetition that took place during the early
vertebrate stage ? what, in fact, caused the disappearance of the
metasomatic appendages, and the formation of the smooth body
surface of the fish ?

The embryological evidence given by v. Wijhe and others of
the manner in which the original superficially situated pronephros
is removed from the surface and caused to assume the deeper
position, as seen in the later embryo, is perfectly clear and
uniform in all the vertebrate groups. The diagrams at the end
of v. Wijhe’s paper, which I reproduce here, illustrate the process.
which takes place. At first the myotome (A, fig. 3) is confined
to the dorsal region on each side of the spinal cord and noto-
chord. Then it (B, fig. 3) separates from the rest of the somite
and commences. to extend ventrally, thus covering over the
pronephros and its duct, until finally (C, fig. 3) it reaches the
mid-ventral line on each side, and the foundations of the great.
somatic body muscles are finally laid.

In order, therefore, to understand how the obliteration of the
appendages took place, we must first find out what is the past.
history of the myotomes; why are they confined at first to the
dorsal region of the body, and afterwards extend to the ventral
region, forcing by their growth an organ that was originally
external in situation to become internal ?

In the original discussion at Cambridge, I was accused of
violating Principle 5,.—In phylogeny we must look at the most
elementary of the animals whose ancestors we seek,—and was
told that the lowest vertebrate was Amphioxus, not Ammocestes;

1 Proc. Cambridge Philos. Soc., vol. ix. p. 19, 1895.

ORIGIN OF VERTEBRATES. 189

Fic. 3A. Fic. 38.

Fie, 30.

Fic, 83—(after v. Wijhe).—., central nervous system ; Ne., notochord; Ao.,
aorta ; Mg., midgut.
A.—My., myoceele ; Mes., mesoceele ; Aet., metaccele ; Hyp., hypomer
(pronephric).
Bp. and c.—My., myotome; Mes., mesonephros; S.d., segmental
duct (pronephric) ; Met., body cavity.

190 DR WALTER H. GASKELL.

that therefore any argument as to the origin of vertebrates.
must proceed from the consideration of the former and not the
latter animal. My reply was then and is still, that I was.
considering the cranial region in the first place, and that there-
fore it was necessary to take the lowest vertebrate which pos-
sessed cranial nerves and sense organs of a distinctly vertebrate
character, a criterion evidently not possessed by Amphioxus,.
Such argument does not apply to the spinal region, so that,.
now that I have left the cranial region and am considering the
spinal, I entirely agree with my critics that Amphioxus is likely
to afford valuable help, and ought to be taken into consideration
as well as Ammoccetes. The distinction between the value
of the spinal (including respiratory) and cranial regions of
Amphioxus for drawing phylogenetic conclusions is recognised
by Boveri, who says! that, in his opinion, “ Amphioxus shows.
simplicity and undifferentiation rather than degeneration. If
truly Amphioxus is somewhat degenerated, then it is so in its.
prehensile and masticatory apparatus, its sense organs, and
perhaps its locomotor organs, owing to its method of living.”

Hatschek describes in Amphioxus how the ccelom splits into:
a dorsal segmented portion, the protovertebra, and a ventral un-
segmented portion, the lateral plates. He describes in the
dorsal part the formation of myotome and sclerotome as in the
Craniota. Also, just as in the latter case, the myotome is at
first confined to the dorsal region in the neighbourhood of the
spinal cord and notochord, and subsequently extends ventrally,
until, just as in Ammoccetes, the body is enveloped in a sheet
of somatic segmented muscles, the well known myomeres.

The conclusion is inevitable: any explanation of the origin
of the somatic muscles in Ammoccetes must also be an explana-
tion of the somatic muscles in Amphioxus, and conversely; so
that if in this respect Amphioxus is the more primitive and
simpler, then the condition in Ammoccetes must be looked
upon as derived from a more primitive condition, similar to
that found in Amphioxus.

Now, it is well known that a most important distinction
exists between Amphioxus and Ammoceetes in the topographical
relations of the ventral portion of this muscle sheet, for in the

1 Op, cit., p. 467.

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ORIGIN OF VERTEBRATES. 1914

former it is separated from the gut and the body cavity by the
atrial space, while in the latter there is no such space. Fiir-
bringer therefore concludes, as I have already mentioned,' that.
this space has become obliterated in the Craniota, but that it
must be taken into consideration in any attempt at formulating
the nature of the ancestors of the vertebrate.

Kowalewsky* described this atrial space as formed by the
ventral downgrowth of pleural folds on each side of the body,
which met in the mid-ventral line and enclosed the branchial
portion of the gut. According to this explanation, the whole
ventral portion of the somatic musculature of the adult Amphi-
oxus belongs to the extension of the pleural folds, the original
body musculature being confined to the dorsal region. This
is expressed roughly on the external surface of Amphioxus by
the direction of the connective tissue septa between the
myotomes. These septa, as is well known, bend at an angle, the
apex of which points towards the head. The part dorsal to the |
bend represents the part of the muscle belonging to the original
body, the part ventral to the bend is the pleural part and
represents the extension into the pleural folds.

Lankester and Willey* have attempted to give another ex-
planation of the formation of the atrial cavity: they look upon
if as originating from a ventral groove, which becomes a canal
by the meeting of two outgrowths from the metapleure on each
side. This canal then extends dorsalwards on each side, and so
forms the atrial cavity; the metapleure still remains in the adult;
the somatic muscles in the epipleure of the adult are the original
body muscles, and not extensions into an epipleuric fold, for
there is no such fold.

This explanation is a possible conception for the post-branchial
portion of the atrium, but is impossible for the branchial region ;
for, as Macbride* points out, as must necessarily be the case,

} Part III. of this series, ‘On the origin of the branchial segmentation,”
This Journal, vol. xxxiii, p. 183.

® “ Weitere Stud. ii. d. Entwick. geschich. d. Amphioxus lanceolatus,” Arch.
f. Mikr, Anat,, Bd. xiii., 1877.

% «The development of the atrial chamber of Amphioxus,” Q. J. Mier. Sci.,
vol, xxxi., 1890.

4 ** Farther remarks on the development of Amphioxus,” by E. W. Macbride,
Q. J. Micr. Sci., vol. xliii. p. 357, 1900.

192 DR WALTER H. GASKELL.

the point of origin of the atrial wall is in all stages of develop-
ment situated at the end of the gill slit. It shifts in position
with the position of the gill slit, but there can be no growing
back of the cavity. Macbride therefore agrees with Kowalewsky
that the atrial cavity is formed by the simultaneous ventral
extension of pleural folds and of the branchial part of the
original pharynx. Thus, in his summing up, he states:!

“5. In the larva practically the whole sides and dorsal portion
of the pharynx represent merely the hyperpharyngeal groove
and the adjacent epithelium of the pharynx of the adult, the
whole of the branchial epithelium of the adult being represented
by a very narrow strip of the ventral wall of the pharynx of
the larva. The subsequent disproportionate growth of this
part of the pharynx of the larva and of the adjacent portion
of the atrial cavity has given the impression that the atrial
cavity grew upwards and displaced other structures, which is
not the case.”

Further, v. Wijhe? states that the atrium extends beyond the
atriopore right up to the anus, just as must have been the case
if the pleural folds originally existed along the whole length of
the body. His words are: “Allerdings hat sich das Atrium
beim Amphioxus lanceolatus eigenthiimlich ausgebildet, indem
sich dasselbe durch den ganzen Rumpf bis an den Anus, d. h. bis
an die Wurzel des Schwanzes ansdehnt.”

We get, therefore, this conception of the origin of the somatic
musculature of the vertebrate. The invertebrate ancestor
possessed on each side along the whole length of its body a
lateral fold or pleuron which was segmented with the body and
capable of movement with the body, because the dorsal longi-
tudinal somatic muscles extended segmentally into each segment
of the pleuron. By the ventral extension of these pleural folds
not only was the smooth body surface of the vertebrate attained,
but also the original appendages obliterated as such, leaving
only as signs of their existence the branchie, the pronephric
tubules, and the sense organs of the lateral line system.

Such an explanation signifies that the somatic trunk muscu-

1 Op, cit.; p. 359.
2 * Beitrige z. Anat. der Kopfregion des Amphioxus lanecolatus,” yon J. W.
van Wijhe, Petrus Camper Deel. 1, Aflevering 2, p. 59.

ds

ial ea ee

ORIGIN OF VERTEBRATES. 193

lature of the vertebrate was derived from the dorsal longitudinal
musculature of the body of the arthropod, and not from the
ventral longitudinal musculature, and that therefore the
equivalent in the primitive arthropod stage of the myotome of
the vertebrate did not give origin to the ventral longitudinal
muscles of the invertebrate ancestor. Now, as I have said, ve
_ Kennel states that in the proccelom of Peripatus a dorsal

part (III. in fig. 1) is cut off which gives origin to the dorsal
body musculature, while the ventral part which remains (I. and
IL. in fig. 1) gives origin in its appendicular portion (I.) to the
muscles of the appendage, and presumably in its ventral somatic
portion (II.) to the ventral longitudinal muscles of the body.
This dorsal cut off part might be called the myotome, in the
same sense as the corresponding part of the proccelom in the
vertebrate is called the myotome. In both cases the muscles
derived from it form only a part of the voluntary musculature
of the animal, and in both cases the muscles in question are
the dorsal longitudinal muscles of the body (to which must
perhaps be added the dorso-ventral body muscles). Now, the
whole of my theory on the origin of vertebrates arose from the
investigation of the structure of the cranial nerves, which led to
the conception that their grouping was not, like the spinal, a dual
grouping of motor and sensory elements, but a dual grouping to
supply two sets of segments, characterised especially by the
different embryological origin of their musculature. The one
set I called the somatic segmentation, because the muscles
belonging to it were the great longitudinal body muscles; the
other I called the splanchnic segmentation, because its muscles
were those connected with the branchial and visceral arches.
According to my theory, this latter segmentation was due to
the segmentation of the appendages in the invertebrate ancestor ;
and in my previous papers, dealing as they do with the cranial
region, attention was especially directed to the way in which
the position of the striated splanchnic musculature could be
explained by a transformation of the prosomatic and mesosomatic
appendages. Now I am dealing with the metasomatic region,
in which it is true the appendages take a very subordinate place,
but still something corresponding to the splanchnic segments
of the cranial region might fairly be expected to exist, and I

VOL. XXXVII. (N.S. VOL. XVII.)—JAN. 1903. 13

194 DR WALTER H. GASKELL.

Fic, 4A. / Fic. 43.

Fic. 44,—Diagram of section through a trilobite-like animal.

B.—Diagram to illustrate suggested obliteration of appendages and the
formation of an atrial cavity by the ventral extension of the pleural
folds.

c.—Diagram to illustrate the completion of the vertebrate type by the
meeting of the pleural folds in the mid-ventral line and the obliter-
ation of the atrial cavity.

Al., alimentary canal; N., nervous system; My., myotome; P/., pleuron ;
App., appendage ; Neph., nephroceele; Met., metaccele ; S.d., segmental duct;

At., atrial chamber; V.Mes., ventral mesentery ; Mes., mesonephros.
The dotted line represents the splanchnopleuric mesoblast in all figures.

—-
<<
“jem

ORIGIN OF VERTEBRATES. 195

therefore desire to emphasise what appears to me to be the fact,
that the musculature, which in the region of the trunk would
correspond to that derived from the ventral segmentation of
the mesoblast in the region of the head, may have arisen not

~ only from the musculature of the appendages, but also from the

ventral longitudinal musculature of the body of the invertebrate
ancestor, for it seems probable that this latter musculature had
nothing to do with the origin of the great longitudinal muscles
of the vertebrate body, either dorsal or ventral.

The way in which I imagine the obliteration of the atrial
cavity to have taken place is indicated in fig. 4B, which is a
modification of a section across a trilobite-like animal as repre-
sented in fig. 44. As is seen, the pleural folds on each side
have nearly met the bulged-out ventral body surface. A
continuation of the same process would give fig. 4c, which is
to all intents and purposes the same as fig. 3c taken from v.
Wijhe, and shows how the segmental duct is left in the remains
of the atrial cavity. The lining walls of the atrial cavity are
represented very black’ in order to indicate the presence of
pigment, as indeed is seen in the corresponding position in
Ammoceetes.

In these diagrams I have represented the median ventral
surface as a large bulged-out bag, without indicating any
structures in it except the ventral extension of the procelom
to form the metaccelom. At present I will leave the space
between the central nervous system and the ventral mesentery
blank, as in the diagrams; in my next paper I hope to discuss
the possible method of formation within this blank space of
the notochord and midgut. .

Boveri’ considers that the obliteration of the atrial cavity
in the higher vertebrates is not complete, but that its presence
is still visible in the shape of the pronephrie duct.

The evidence of Maas and others that the duct is formed by
the fusion of the pronephric tubules is, it seems to me, conclusive
against Boveri’s view; but yet, as may be seen from my
diagrammatic figures, the very place where one would expect
to find the last remnant of the atrial cavity is where the
pronephric duct is situated.

1 Op. ott,

196 - DR WALTER H. GASKELL.

For my own part I should expect to find evidence of a
former existence of an atrial cavity rather in the pigment
round the pronephros and its duct than in the duct itself.

The conception that Amphioxus shows us how to account
for the great envelope of somatic muscles which wraps round
the vertebrate body, in that the ancestor of the vertebrate
possessed on each side of the body a segmented pleuron, is
exactly in accordance with the theory of the origin of verte-
brates deduced from the study of Ammoccetes, as already set
forth in this series of papers; for we see that one of the
striking characteristics of such forms as Bunodes, Hemiaspis,
etc. is the presence on each side of the main part of the body
of segmented pleural flaps; and if we pass further back to the
great group of Trilobites, we find in the most manifold form and
in various degrees of extent the most markedly segmented
pleural folds. In fact the hypothetical figure (fig. 44) which
I have deduced from the embryological evidence might very
well represent a cross section of a trilobite, provided only that
each appendage of the trilobite possessed an excretory coxal
gland.

The earliest fishes, then, ought to have possessed segmented
pleural folds, which were moved by somatic muscles, and
enveloped the body after the fashion of Ammocetes and
Amphioxus, and I cannot help thinking that Cephalaspis
shows in this respect also its relation to Ammocetes. It is
well known that some of the fossil representatives of the
Cephalaspids show exceedingly clearly that these animals
possessed a very well segmented body, and it is equally recog-
nised that this skeleton is a calcareous, not a bony skeleton, and
does not represent vertebre, etc. It is generally called an
aponeurotic skeleton, meaning thereby that what is preserved
represent not dermal plates alone or a vertebrate skeleton, but
the calcified septa or aponeuroses between a number of muscle
segments or myomeres, precisely of the same kind as the septa
between the myomeres in Ammoccetes. The termination of
such septa on the surface would give rise to the appearance of
dermal plates or scutes, or even the septa may have been attached
to something of the nature of dermal plates. The same kind of
picture would be represented if these connective tissue dis-

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ORIGIN OF VERTEBRATES. 197

sepiments of Ammoccetes were calcified, and then the animal
was fossilised. In agreement with this interpretation of the
spinal skeleton of Cephalaspis, it may be noted that again and
again in parts of these dissepiments I have found in old
specimens of Ammoccetes nodules of cartilage formed, and at
transformation it is in this very tissue that the spinal cartilages
are formed.

Fic. 53.

Fig, 54,'—Facsimile of Woodward’s drawing of a specimen of Cephalaspis
Murchisoni, as seen from the side. The cephalic shield is on the
right and caudal to it the pleural fringes are well shown.

B.—Another specimen of Cephalaspis Murchisoni taken from the same
block of stone, showing the dermo-septal skeleton and in one
place the pleural fringes, bc.

Now, the specimens of Cephalaspis all show, as seen in fig.
5, that the skeletal septa cover the body regularly, and then
along one line are bent away from the body to form as it were

1 British Museum Catalogue of Fossil Fishes, by A. 8. Woodward, part ii.
pl. x. fig. 1. London, 1891.

198 DR WALTER H. GASKELL.

a fringe, or rather a free pleuron, which has been easily pushed
at an angle to the body skeleton in the process of fossilisation.
I had the pleasure of seeing Prof. Patten in Cambridge this last
summer (1901), and he drew my attention especially to this
fringed edge. He thinks it is evidence of a number of segmental
appendages which were jointed to the corresponding body seg-
ments, and in the best specimen at the South Kensington Natural
History Museum he thinks such joints are clearly visible. He
concludes, therefore, that the Cephalaspids were Arthropods,

Fic. 68.

Fie. 6a.—Arrangement of septa in Ammoccetes. NVC, position of notochord,
B,—Arrangement of septa in Amphioxus.

and not Vertebrates. I have also carefully examined this
specimen, and do not consider that what is seen resembles the
joint of an arthropod appendage; the appearance is rather such
as would be produced if the line of attachment of Patten’s
appendages to the body was the place where the pleural body
folds became free from the body, and so with any pressure a
bending or fracture of the calcified plates would take place along
this line.

There is undoubtedly an appearance of finish at the termina-
tion of these skeletal fringes, as though they terminated in a
definitely shaped spear-like point, just as is seen in the trilobite

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ORIGIN OF VERTEBRATES. 199

pleure. This again, to my mind, is rather evidence of pleural

fringes than of true appendages.

As already argued, I look upon Ammoceetes as the only living
fish at all resembling the Cephalaspids; it is therefore instructive
to compare the arrangement of this spinal dermo-septal skeleton
of Cephalaspis with that of the septa between the myomeres in

_ the trunk region of Ammoccetes and Amphioxus. Such a

skeleton in Ammoccetes would be represented by a series of
plates overlapping each other, arranged as in fig. 6A, and in
Amphioxus as in fig. 68. I have lettered the corresponding parts

_ of the two structures by similar letters, a, 6, « Ammoccetes

differs in configuration from Amphioxus in that it possesses an
extra dorsal (a @) and an extra ventral bend. Ammoccetes is a
much rounder animal than the Amphioxus, and both the dorsal
and ventral bends are on the extreme ventral and dorsal surfaces,
surfaces which can hardly be said to exist in Amphioxus. The
part, then, of such an aponeurotic skeleton of Ammoccetes which
I imagine corresponds to 6 ¢ in Amphioxus, and therefore would
represent the pleural fold, is the part ventral to the bend at 3.
In both animals this bend corresponds to the position of the
notochord NC. _

The skeleton of Cephalaspis compares more directly with that
of Ammoccetes than of Amphioxus, for there is the same extra
dorsal bend (ad) as in Ammoccetes; the lateral part of the
skeleton again gives an angle ac; the part from b to ¢ would
therefore represent the pleural fold. I picture to myself the
sequence of events somewhat as follows:

First, a protostracan ancestor, which like Peripatus possessed
appendages on every segment into which ccelomic diverticula
passed, forming a system of coxal glands. Such glands being
derived from the segmental organs of the Cheetopods, originally
discharged to the exterior by separate openings on each segment;
it is, however, possible, and I think probable, that a fusion of
these separate ducts had already taken place in the protostracan
stage, so that there was only one external opening for the whole
of these metasomatic coxal glands, just as there is only one
external opening for the corresponding prosomatic coxal glands
of Limulus. Then, by the ventral growth of pleural body folds,
such appendages became enclosed and useless, and the coxal

200 DR WALTER H. GASKELL.

glands of the post-branchial segments, with their segmental or
pronephric duct, were all that remained as evidence of such
appendages. This dwindling of the metasomatic appendages
was accompanied with the getting rid of free appendages
generally, in the manner set forth in these papers, and so a
smooth fish-like body surface was formed; then came elongation
for the purpose of increasing mobility by the addition of seg-
ments between those last formed and the cloacal region; each
of such new formed segments was" appendageless, so that its
segmental organ was not a coxal gland, but entirely somatic
in position: formed, therefore, a mesonephric tubule, not a
pronephric one. Such glands could no longer excrete to the
exterior, owing to the exclosing shell of the pleural folds, but the
pronephric duct was there, already formed, and so these nephric
tubules opened into that, instead of, as in the case of the
branchial slits, forcing their way through the pleural walls
when the atrium became closed.

The Meaning of the Ductless Glands. —

If itis a right conception, that the excretory organs of the
protostracan group, which gave origin to the vertebrates as
well as to the crustaceans and arachnids, were of the nature of
coxal glands, then it follows that such coxal glands must have
existed originally on every segment, because they themselves’
were derived from the segmental organs of the annelids, and
it is therefore worth making an attempt to trace the fate of
such segmental organs in the Vertebrate as well as in’ the
Crustacean and Arachnid.

Such an attempt is possible, it seems to me, because there
exists throughout the animal kingdom striking evidence that —
excretory organs which no longer excrete to the exterior do
not disappear, but still perform excretory functions of a different
character. Their cells still take up effete or injurious substances,
and instead of excreting to the exterior, excrete into the blood,
forming either ductless glands of special character, or glands of
the nature of lymphatic glands.

The problem presented to us is as follows :—

The excretory organs of both arthropods and vertebrates”

ORIGIN OF VERTEBRATES. 201

arose from those of annelids, and were therefore originally
present in every segment of the body. In most arthropods
and vertebrates they are present only in certain regions, in the
former case as the coxal glands of the prosomatic or head
region, in the latter as the nephric glands of the metasomatic

~ or trunk region, and in the case of Amphioxus of the mesosomatic

or branchial region.

In the original arthropod, judging from Peripatus, they were
present, as in the annelid, in all the segments of the body, and
formed coxal glands.

Therefore, in the ancestors of the living Crustacea and
Arachnida, coxal glands must have existed in all the segments
of the body, and we ought to be able to find the vestiges of
them in the mesosomatic or branchial and metasomatic or
abdominal regions of the kody.

Similarly in the vertebrates, derived, as has been shown, not
from the annelids, but from an arthropod stock, evidence of
the previous existence of coxal glands ought to be manifested
in the prosomatic or trigeminal region, in the mesosomatic or
branchial region, as well as in the metasomatic or post-branchial
region.

How does an excretory organ change its character when it
ceases to excrete to the exterior? what should we look for
in our search after the lost coxal glands ?

The answer to these questions is most plainly given in the
case of the pronephros, especially in Myxine, where Maas!
has been able to follow out the whole process of the conversion
of nephric tubules into a tissue resembling that of a lymph gland.

He states, in the first place, that the pronephros possesses a
capillary network, which extends over the pronephric duct,
while the tubules of the mesonephros possess not only this
capillary network, equivalent to the capillaries over the
convoluted tubules in the higher vertebrates, but also a true
glomerulus, in that the nephric segmental arteriole forms a
snarl (knauel), and pushes in the wall of the mesonephric
tubule (see fig. 28, pl. xli.). He describes* the pronephros of
large adult individuals as consisting of—

1. Tubules with funnels which open into the pericardial ccelom.

1 Op, cit. 2 Tbid., p. 486,

202 DR WALTER H. GASKELL.

2. A large capillary network (the glomus) at the distal end.

3. A peculiar tissue (the strittige Gewebe of the Semon-
Spengel controversy), which Spengel considers to be composed
of the altered epithelium of pronephric tubules, while Semon
looks on it as an amalgamation of glomeruli.

Maas is entirely on the side of Spengel, and shows that this
peculiar tissue is actually formed by modified pronephric
tubules, which become more and more lymphatic in character.

He says:! “The pronephros consists of a number of nephric
tubules, placed separately one behind the other, which were
originally segmental in character, each one of which is supplied
by a capillary network from a segmental branch of the aorta.
The tubules begin with many mouths (dorso-lateral and medial-
ventral) in the pericardial cavity; on their other blind end
they have lost their original external opening, and there, in the
cranial portion.of the head kidney, before they have joined together
to form a collecting duct, they, together with the vascular net-
work, are transformed into a peculiar adrenal-like tissue. The
most posterior of the segmental capillary nets retain their
original character, and are concentrated into the separate
capillary mass known as the glomus.”

Later on? he says: “Further, the separate head kidney is
more and more removed in structure from an excretory organ
in the ordinary sense. One cannot, however, speak of it as an
organ becoming rudimentary; this is proved not only by the
progressive transformation of its internal tissue into a tissue
of a very definite character, but also by the cilia in its canals
and the steady increase in the number of its funnels. It
appears, therefore, to be the conversion of an excretory organ
into an organ for the transference of fluid out of the ccelom
into a special tissue, ze. into its blood sinus; in other words,
into an organ which must be classed as belonging to the lymph
system.”

In exact correspondence with this transformation of a nephric
tubule into a ductless gland of the nature of a lymphatic gland,
is the formation of the head kidney in Teleosteans. Thus

Weldon points out® that “though the observations of Balfour
1 Ibid., p. 497. 2 Thid., p. 504.
3 “On the suprarenal bodies of Vertebrates,” by W. F. R. "Weldon, Q. J. Micr.
Sez., vol. xxv. p. 147,

.
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.

ORIGIN OF VERTEBRATES. 203

left it highly probable that the ‘lymphatic’ tissue described by
him was really a result of the transformation of part of the

embryonic kidney, he did not investigate the details of its

development. This was afterwards done by Emery,' with the
following results.

“In those Teleostei which he has studied, Professor Emery
finds that at an early stage the kidney consists entirely of a
single pronephric funnel, opening into the pericardium, and
connected with the segmental duct, which already opens to the
exterior. Behind this funnel, the segmental duct is surrounded
by a blastema, derived from the intermediate cell mass, which
afterwards arranges itself more or less completely into a series
of solid cords, attaching themselves to the duct. These develop
a lumen and become normal segmental tubules, but it is, if I
may be allowed the expression, a matter of chance how much
of the blastema becomes so transformed into kidney tubules,
and how much is left as the ‘lymphatic’ tissue of Balfour, this
‘lymphatic ’ tissue remaining either in the pronephros only, or
in both pro- and meso-nephros.”

If we turn now to the invertebrates, we see also how sie a
connection exists between lymphatic and phagocytic organs and
excretory organs. The chief merit for this discovery is due to
Kowalewsky, who, taking a hint from Heidenhain’s work on the
kidney, in which he showed how easy it was to find out the
nature of different parts of the mammalian excretory organ by
the injection of different substances, such as a solution of
ammoniated carmine or of indigo-carmine, has injected into a
large number of different invertebrates various colouring matters,
or litmus, or bacilli, and thus shown the existence not only of
known excretory organs, but also of others, lymphatic or lymphoid
in nature, not hitherto suspected.

In all cases he finds that a phagocytic action with respect to
solid bodies is a property of the leucocytes, that these leucocytes
which are found in the ccelomic spaces of the Annelida, etc. are
apparently derived from the epithelium of such spaces, that by

- the proliferation of such epithelium in places, eg. the septal

glands of the terrestrial Oligocheta, segmental glandular masses
of such tissue are formed which take up the colouring matter,
1 Alti dell’ Acad, d. Lincei, 1882.

204 DR WALTER H. GASKELL.

etc. That in the limicolous Oligocheta such septal glands are
not found, but that at the commencement of the nephridial
organ, immediately following upon the funnel, a remarkable
modification of the nephridial wall takes place to form a large
cellular cavernous mass, the so-called filter, which in Euaxes is
full of leucocytes, the cells are only definable by their nuclei,
and look like and act in the same way as the free leucocytes
outside this nephridial appendage. As G. Schneider! points out,
the whole arrangement is very like that described by Kowal-
ewsky? in the leeches Clepsine and Nephelis, where, also
immediately succeeding the funnel of the nephridial organ, a
large accessory organ is found, which is part of the nephridium,
and is called the nephridial capsule. This is the organ par
excellence which takes up the solid carmine grains, bacillus, ete.,
and apparently, from Kowalewsky’s description, contains leu-
cocytes in large numbers.

We see, then, that in such invertebrates, just as in the ware
brate, modifications of the true excretory organ may give rise to
phagocytic glands of the nature of lymphatic glands.

Further, these researches of Kowalewsky suggest in the very
strongest manner that whenever by such means new, hitherto
unsuspected glands are discovered, such glands must belong to
the excretory system, i.e. must be derived from coelomic epi-
thelium, even when all evidence of any ccelom has disappeared.
Kowalewsky himself was evidently so impressed with the same
feeling that he heads one of his papers* “The excretory organs
of the Pantopoda,” although the organs in question have been
discovered by him by this method, and appeared as ductless
glands with no external opening.

To my mind these observations of Kowalewsky are of exceed-
ing interest, for itis immediately clear that if thesegmental organs
of the annelids, which must have existed on all the segments
of the forefathers of the crustacea and arachnida (the Protostraca),

1 “Ueber phagocytire Organe und Chloragogenzellen der Oligocheta,” v. G.
Schneider, Zeit. f. wiss. Zool., Bd. 61, p. 363, 1896.

7” « tude Biologique sur les Clepsines,” Mém. de U’ Acad. Imp. d. Sci. de St
Petersbourg, viii. sér., 1897.

3 «Kin Beitrag zur Kenntniss der Excretionsorgane der Pantopoden,” yon A.
Kowalewsky, Mém. d. lAcad. Imp. d. Sci. d. St Petersbowrg, vii. sér., vol.
XXxXvViii., 1890.

ORIGIN OF VERTEBRATES. 205

have left any sign of their existence in living crustaceans and
arachnids, then such indication would most likely take the form
of lymphatic glands in the places where the excretory organs
ought to have been.
| Now, as already pointed out in Peripatus, such segmental
organs were formed by the ventral part of the ccelom, and dipped
originally into each appendage ; also we know that each segment
of an arachnid embryo possesses a coelomic cavity in its ventral
part which extends into the appendage on each side; this cavity
afterwards disappears, and is said to leave no trace in the adult
of any excretory coxal gland derived from its walls. If, however,
it is found that in the very position where such organ ought to
have been formed a segmentally arranged ductless gland is
situated, the existence of which is shown by its taking up of
‘carmines, etc., then it seems to me that in all probability such
gland is the modification of the original coxal gland.

This is what Kowalewsky! has done. Thus he states that
Metschnikoff had fed Mysis with carmine grains, and found
tubules at the base of the thoracic feet coloured red with car-

“mine. He himself used an allied species, Paropodopsis cornutum,
and found here also that the carmine was taken up by tubules
situated in the basal segments of the feet.

In Nebalia, feeding experiments with alizarin blue and carmine
stained the antennal glands, and showed the existence of glands
‘at the base of the eight thoracic feet. These glands resemble
the foot glands of Mysis, Parapodopsis, and Palemon, and lie in
the space through which the blood passes from the thoracic feet,
i.e. from the gills to the heart.

In Squwilla also, in addition to the shell glands, special glands
were discovered on the branchial feet on the path of the blood
to the heart. These glands form continuous masses of cells
which constitute large compact glands at the base of the branchial
feet. Single cells of the same sort are found along the whole
course of the branchial venous canal, right up to the pericardium.

These observations show that the Crustaceans possess not only
true excretory organs in the shape of coxal glands, 7.e. antennary
glands, shell glands, etc., in the cephalic region, but also a series

1 «in Beitrag zur Kenntniss der Excretionsorgane,” Biologisches Central-
blatt, 1889.

206 DR WALTER H. GASKELL.

of segmental glands situated at the base of the appendages,
especially of the respiratory appendages :—a system, that is to
say, of coxal glands which had lost their excretory function,
having lost their external opening, but had not in consequence
disappeared, but still remained im situ, and still retained an
important excretory function, having become lymphatic glands
containing leucocytes. Such are especially found in the branchial
appendages, and are called by Cuénot,! who describes them for
all Decapods, as branchial glands.

Further, it is significant that the same method reveals the
existence in Pantopods? of a double set of glands of similar
character, one set in the basal segments of the appendages and
the other in the adjacent part of the body.

‘Also in scorpions, Kowalewsky* has shown that the remark-
able lymphatic organ situated along the whole length of the
nerve cord in the abdominal region takes up carmine grains and
bacilli, an organ which in Androctonus does not form one con-
tinuous gland, but a number of separate apparently irregularly
grouped glandular bodies. |

In addition to this median lymphatic gland, Kowalewsky has
discovered in the scorpion a pair of lateral glands, to which he
gives the name of lymphoid glands, which communicate with the
thoracic body cavity (7.e. the pseudo-ccele), are phagocytic, and
according to him give origin to leucocytes by the proliferation
of their lining cells, thus, as he remarks, reminding us of the
nephridial capsules of Clepsine. These glands are so closely
related in position to the coxal glands on each side, that he has
often thought that the lumen of the gland communicated with
that of the coxal gland; he, however, has persuaded himself that
there is no true communication between the two glands.

Neither of these organs appear to be segmental, and until we
know how they are developed, it is not possible to tell whether
they represent fused segmental organs or not.

The evidence, then, is very strong that in the Crustacea and

1 « Etudes sur le sang et les glandes lymphatiques dans la série animale” (2nd
partie: invertébrés), par L. Cuénot, Arch. d. Zool. exper. gen., 2 sér. T. 9,
1891, 2 Op. cit.

’ “Une nouvelle glande lymphatique chez le scorpion d’Europe,” par A.
Kowalewsky, Mém. d, ? Acad, Imp, d. Sci, d. St Petersbourg, viii. sér., vol.
v., 1897.

ORIGIN OF VERTEBRATES. 207

Arachnida the original segmental excretory organs do not
disappear, but remain as ductless glands, of the nature of
lymphatic glands, which supply leucocytes to the system.

Further, the evidence shows that the nephric organs, or parts
of the ccelom in close connection with these organs, may be
transformed into ductless glands, which do not necessarily
contain free leucocytes like lymph glands, but yet are of such
great importance as excretory organs that their removal pro-
foundly modifies the condition of the animal. Such a gland
is the so-called adrenal or suprarenal body, disease of which is
a feature of Addison’s disease ; a gland which forms and presum-
ably passes into the blood a substance of remarkable power in
causing contraction of blood-vessels, a substance which has lately
been extracted in crystalline form by Jokichi Takamine, and
called by him ‘adrenalin’: a gland, therefore, of very distinct
peculiar properties, which cannot be regarded as rudimentary,
but as of vital importance for the due maintenance of the
healthy state.

In the Elasmobranchs two separate glandular organs have
been called suprarenal, a segmental series of paired organs, each
of which possesses a branch of the aorta and a sympathetic
ganglion, and an unpaired series in close connection with the
kidneys, to which Balfour gave the name of interrenal glands.

Of these two sets of glands, Swale Vincent has shown that the
extract of the interrenals has no marked physiological effect, in
this respect resembling the extract of the cortical part of the
mammalian gland, while the extract of the paired segmental
organs of the Elasmobranch produces the same remarkable rise of
blood pressure as the extract of the medullary portion of the
mammalian gland.

Also the development of these two sets of glands is asserted
to be different. Balfour considered that the suprarenal were
derived from sympathetic ganglion cells, but left the origin of
the interrenal doubtful. Weldon? showed that the cortical part
of the suprarenals in the lizard was derived from the wall of the
glomerulus of a number of mesonephric tubules: In Pristiurus,

1 “The isolation of the active principle of the suprarenal gland,” by Jokichi
Takamine, Proc. of the Physiol. Soc,, Dec. 14, 1901: Journ. of Physiol., vol.
xxvii. * Op. cit,

208 DR WALTER H. GASKELL.

he stated that the mesoblastic rudiment described by Balfour as
giving origin to the interrenals is derived from a diverticulum
of each segmental tubule, close to the narrowing of its funnel-
shaped opening into the body cavity. With respect to the
paired suprarenals he was unable to speak positively, but
doubted whether they were derived entirely from sympathetic
ganglion.

Weldon sums up the results of his observations by saying!
“that all Vertebrates except Amphioxus have a portion of the
kidney modified for some unknown purpose not connected with
excretion; that in Cyclostomes the pronephros alone is so
modified, in Teleostei the pro- and part of the meso-nephros ;
while in the Elasmobranchs and the higher Vertebrates, the
mesonephros alone gives rise to this organ, which has also in
these forms acquired a secondary connection with certain of the
sympathetic ganglia.”

Since Weldon’s paper, a large amount of literature on the
origin of the adrenals has appeared, a summary of which up to
1891 is given by Hans Rab]? in his paper, and a further summary
by Aichel*® in his paper published in 1900. The result of the
investigations up to this latter paper may be summed up by
saying that the adrenals, using this term to include all these
organs of whatever kind, are in all cases partly at all events
derived from some part of the walls of either the mesonephric
or pronephric excretory organs, but that in addition a separate
origin from the sympathetic nervous system must be ascribed to
the medullary part of the organ and to the separate paired organs
in the Elasmobranchs, which are equivalent to the medullary part
in other cases.

I must say that I cannot believe in the traniafomniaaie of nerve
cells into a glandular organ, and therefore am very pleased to
find that Aichel’s observations show that such is not the case,
but that the suprarenals of Elasmobranchs are in the earliest
stage derived from the transverse portion of the mesonephric

1 “* Note on the origin of the suprarenal bodies in Vertebrates,” Proc. Roy.
Soc., vol. xxxvil. p. 424, 1884.

2 «Die Entwick. u. Struct. d. Nebennieren b, d. Vogeln,” von Hans Rabl,
Arch, f. Mikr, Anat., Bd. xxxviii. p. 492, 1891,

* “ Vergleich. Entwick. geschich. u. Stam. geschich. d. Nebennieren,” von O.
Aichel, Arch, f. Mikr. Anat., vol. lvi. p. 1, 1900.

ORIGIN OF VERTEBRATES. 209

tubules which have lost their connection with the epithelium of
the body cavity, the funnel of these tubules disappearing. Soon
a sympathetic ganglion comes into close contact with this modi-
fied nephric diverticulum, and so the adult organ is formed.

He also states that the interrenals are formed before the
suprarenals, and commence at a time when the mesonephric
tubule has not yet become joined to the segmental duct. They
commence as a cellular protuberance on the inner wall of the
mesonephric funnel.

In higher vertebrates (Rodents, etc.) Aichel finds that the
adrenals arise in close connection with the mesonephric funnels ;
the sympathetic ganglia have no connection at first, but come
later into close contact with the adrenals; there is no reason
to suppose that any part of the glandular substance is derived
from the modification of nerve cells. As he says, he entirely
agrees with and confirms Weldon’s point of view.

It is to my mind especially interesting to notice how, according
to both Weldon and Aichel, the adrenals, or at all events the
interrenals, arise from the same part of the nephric tubule as
the nephridial capsules described in Kowalewsky’s papers! for
both leeches and certain worms :—In all cases a bulging of the
wall of the nephridium close to its funnel-shaped opening into
the body cavity.

Swale Vincent* appears to object strongly to Aichel’s
statements on the ground of his physiological experiments as to
the action of suprarenal extract, the activity being confined to
the medullary portion of the mammalian gland, and to the paired
suprarenals of the elasmobranch, always in fact to the part of the
gland containing sympathetic nerve cells; and he says that the
evidence of Leydig, Balfour, etc. for the origin of the medullary
part from sympathetic cells is so strong, and the physiological
evidence of a difference of origin of the two parts of the gland so
convincing, that he does not imagine that many morphologists or
physiologists will be found to accept Aichel’s teaching. I should
have thought myself that no physiologist would accept the
doctrine of the conversion of nerve cells into glandular tissue,
and would be glad therefore to find that it was not necessary to
do so; such appears also to have been previously the opinion of

1 Op. cit, 2 Anat, Anzeiger, Bd, xviii,, 1900, p. 74.

VOL. XXXVII. (N.S, VOL, XVII.)—JAN. 1903. 14

210 DR WALTER H. GASKELL.

Swale Vincent, for, talking of the segmental suprarenal bodies
of the elasmobranch, he says,! “I am inclined to think that the
connection between the sympathetic nervous system and these
bodies has been overstated. They are intimately involved in
the sympathetic plexuses, and often have tiny ganglia very close
to them; but in the adult, at any rate, whatever their develop-
mental relations may be, i can, in my opinion, not be truly said
that they are an integral part of the sympathetic nervous system.” ®

The evidence, then, of the transformation of the known
vertebrate excretory organs—the pronephros and the meso-
nephros—leads to the conclusion that in our search for the
missing coxal glands of the meso- and pro-somatic regions we
must look for either lymphatic glands or ductless glands of
distinct importance to the body. I have already considered the
question in the prosomatic region,® and have given my reasons:
why the pituitary gland must be looked upon as the descendant
of the arthropod coxal gland. In this case also the resulting
ductless gland is still of functional importance, for disease
of it is associated with acromegaly. If, as is possible, it is
homologous with the Ascidian hypophysial gland, then it is.
confirmatory evidence that this latter is said by Julin to be an
altered nephridial organ.

Finally, I come to the mesomatic or branchial region; and
here, strikingly enough, we find a perfectly segmental glandular
organ of mysterious origin—the thymus gland—segmental with
the branchie, not necessarily with the myotomes, belonging
_ therefore to the appendicular system ; and since the branchie re-
present, according to the theory; the basal part of the appendage,
such segmental glands would be in position coxal glands, Here,
then, in the thymus may be the missing mesosomatic coxal eee

What, then, is the thymus ?

The answer to this question has been given rebenitly by
Beard,* who strongly confirms Koélliker’s original view that the

1 « Contributions to the comparative anatomy and histology of the suprarenal
capsules,” by Swale Vincent, Z’rans, Zool. Soc. Lond., vol. xiv., part iii., 1897,.
p. 53. 2 The italics are Swale Vincent’s.

* Part VI. of this series of papers: ‘‘ The old mouth and the olfactory organ =
meaning of the pituitary body,” This Jowrnal, vol. xxxiv, p. 532.

‘ “The source of leucocytes and the true function of the yee ” Anat.
Anzeiger, vol, xviii. p. 550, 1900.

ORIGIN OF VERTEBRATES. 211

thymus is a gland for the manufacture of leucocytes, and that
‘such leucocytes are directly derived from the epithelium cells of

- the thymus. Kolliker also further pointed out that the blood

of the embryo is for a certain period destitute of leucocytes.

Beard confirms this last statement, and says that up to a
certain stage (varying from 10-16 mm. in length of the embryo)
the embryos of Faja batis have no leucocytes in the blood or
elsewhere ; up to this period the thymus placode is well formed,
and the first leucocytes can be seen to be formed in it from its
epithelial cells; then such formation takes place with great
rapidity, and soon an enormous discharge of leucocytes occurs
from the thymus into the tissue spaces and blood; he therefore
- concludes that all lymphoid tissues in the body arise originally
from the thymus gland, i.e. from leucocytes discharged from
the thymus. a

The segmental branchial glands known by the name of
thymus are, according to this view, the original lymphatic glands
of the vertebrate, and it is to be noted that in fishes and in
amphibia lymphatic glands, such as we know them in the
higher mammals, do not exist; they are characteristic of the
higher stages of vertebrate evolution. In the lower vertebrates
the only glandular masses apart from the cell lining of the
body cavity itself, which give rise to leucocyte-forming tissue,
are these segmental branchial glands, or possibly also the
modified post-branchial segmental glands, known as the head
kidney in Teleosteans, etc.
_ The importance ascribed by Beard to the thymus in the
formation of leucocytes in the lowest vertebrates would be
considerably reduced in value if the branchial region of
Ammoceetes possessed neither thymus glands nor anything
equivalent to them. Such, however, is not the case; Schaffer?
has shown that in the young Ammocecetes masses of lymphatic
glandular tissue are found segmentally arranged in the neighbour-
hood of each gill slit, tissue which soon becomes converted into
a swarming mass of leucocytes, and shows by its staining, ete.
how different it is from a blood space. The presence of this
thymus leucocyte-forming tissue, as described by Schaffer, is

1 "Ueber die Thymusanlage bei Petromyzon Planeri,” von J. Schaffer,
Sittingsber. d. Kais, Akad, d. Wiss, in Wien, Bd, 103, 1894.

212 DR WALTER H. GASKELL.

confirmed by Beard, and I myself have seen the same thing in
my youngest specimen of Ammoccetes.

Further, the very methods by which Kowalewsky has brought
to light the segmental lymph glands of the branchial region of
the Crustacea, ete., are the same as those by which Weiss! dis-
covered the branchial nephric glands in Amphioxus: excretory
organs which Boveri? considers to represent the pronephros of
the Craniota. In this supposition Boveri is right in so far that
both pronephros and the tubules in Amphioxus belong to the
same system of excretory organs, but I entirely agree with v.
Wijhe? that the region in Amphioxus is wrong. The tubules.
in Amphioxus ought to be represented in the branchial regions.
of the Craniota, not in the post-branchial region; v. Wijhe
therefore* suggests that further researches may homologise
them with the thymus gland in the Craniota, not with the
pronephros. . GS

This suggestion of v. Wijhe appears to me a remarkably good
one, especially in view of the position of the thymus glands in
Ammoccetes and the nephric branchial glands in Amphioxus.
If, as I have pointed out, the atrial cavity of Amphioxus has
been closed in Ammoccetes by the apposition of the pleural fold
with the branchial body surface, then the remains of the position
of the atrial chamber must exist in Ammoccetes as that extra-
ordinary space between the somatic muscles and the branchial
basketwork filled with blood spaces and modified muco-cartilage.
It is in this very space close against the gill slits where the
thymus glands of Ammoccetes are found, in the very place
where the nephric tubules of Amphioxus would be found if its
atrial cavity were closed completely. Instead, therefore, of
considering with Boveri that the branchial nephric tubules of
Amphioxus still exist in the Craniota as the pronephros, and
that the atrial chamber has narrowed down to the pronephric
duct, I would agree with v. Wijhe that the pronephros is post-
branchial, and suggest that by the complete closure of the atrial
space in the branchial region the branchial nephric tubules

1 Op. cit. 2 Op, cit.

3 ** Beitriige z. Anat. u. der Kopfregion des Amphioxus lanceolatus,” von J.
W. van Wijhe, Petrus Camper Deel, 1, Aflevering 2.

4 Op. cit., p. 58.

Ee ee ee hy a

et ire aL Ll

a ee eT ee er re ON Re eng 0 Vega toe

ORIGIN OF VERTEBRATES. 213

have lost all external opening, and consequently, as in all other

eases, have changed into lymphatic tissue and become the
_ segmental thymus glands.
_ As vy. Wijhe himself remarks, the time is hardly ripe for

making any positive statement about the relationship between
the thymus gland and branchial excretory organs. There is
at present not sufficient consensus of opinion to enable us to
speak with any certainty on the subject, yet there is so much
suggestiveness in the various statements of different authors as

_ to make it worth while to consider the question briefly.

On the one hand, thymus, tonsils, parathyroids, epithelial
cell nests and parathymus are all stated to be derivatives of

_ the epithelium lining the gill slits, and Maurer! would draw a

distinction between the organs derived from the dorsal side of
the gill cleft and those derived from the ventral side; the
former being thymus, the latter forming the (epithelial K6rper)
epithelial cell nests, i.e. parathyroids. The thymus in Ammo-
ceetes, according to Schaffer, lies both ventral and dorsal to the
gill cleft ; Maurer thinks that only the dorsal part corresponds
to the thymus, the ventral part corresponding to the para-
thyroids, ete. Structurally, the thymus, parathyroids and the
epithelial cell nests are remarkably similar, so that the evidence
appears to point to the conclusion that in the neighbourhood of
the gill slits segmentally arranged organs of a lymphatic character
are situated, which give origin to the thymus, parathyroids,
tonsils, ete.

Now among these organs, ic. among the ventrally situated
ones, Maurer places the carotid gland, so that if he is right, the
origin of the carotid gland might be expected to help in the
elucidation of the origin of the thymus.

The origin of the carotid gland has been investigated recently
by Kohn,? who finds that it is associated with the sympathetic
nervous system in the same way as the suprarenals. He desires,
in fact, to make a separate category for such nerve glands, or
paraganglia, as he calls them, and considers them all to be
derivatives of the sympathetic nervous system, and nothing to

1 “Die Schilddriise, Thymus und andere Schlundspaltenderivate bei der
Eidechse,” von F. Maurer, Morphol, Jahrbuch, Ba, xxvii. p. 119, 1899.

2 ** Ueber den Bau und die Entwicklung der sog, Carotis driise,” von A. Kohn,
Archiv f. Mikr. Anat,, Bd, lvi. p. 81, 1900.

214 DR WALTER H. GASKELL.

do with excretory organs. The carotid gland is, according to
him, the foremost of the suprarenal masses in the Elasmobranchs,
viz., the so-called axillary heart.

In my opinion, nests of sympathetic ganglion cells necessarily
mean the supply of efferent fibres to some organ, for all such
ganglia are efferent, and also, if they are found in the organ,
would have been taken in by the blood-vessels supplying the
organ, so that, as already stated, Aichel’s statement of the origin
of the suprarenals in the Elasmobranchs seems to me much
more likely than a derivation from nerve cells. If, then, it
prove that Aichel is right as to the origin of the suprarenals,
and Kohn is right in classifying the carotid gland with the
_suprarenals, then Maurer’s statements would bring the para-
thyroids, thymus, etc. into line with the adrenals, and suggest
that they represented the segmented glandular excretory organs
‘of the branchial region, into which, just as in the interrenals
-of Elasmobranchs, or the cortical part of the adrenals of the
‘higher vertebrates, there has been no invasion of aye
ganglion cells.

. Wheeler! makes a most suggestive remark in his paper on
Petromyzon: he thinks he has obtained evidence of serial
homologues of the pronephric tubules in the branchial region
of Ammoceetes, but has not been able up to the present to
follow them out.

- If what he thinks to be serial homologues of the pronephric
tubules in the branchial region should prove to be. the origin
of the thymus glands of Schaffer, then v. Wijhe’s suggestion
that the thymus represents the excretory organs of the branchial
region would gain enormously in probability. Until some such
further investigation has been undertaken, I can only say that
it seems to me most likely that the thymus, etc. represent the
lymphatic branchial glands of the Crustacea, and therefore re-
present the missing coxal glands of the branchial region.

This, however, is not all, for the appendages of the mesosomatic
region, as I have shown, do not all bear branchie ; the foremost
or opercular appendage carries the thyroid plata again the
basal part of the appendage is all that is left, the thyroid gland
is in position a coxal gland. It ought therefore to represent

1 Op. cit., p. 22¢

i eh pail ee a es es ae

ORIGIN OF VERTEBRATES, 215-

the coxal gland of this appendage, just as the thymus, tonsils,
ete. represent the coxal glands of the rest of the mesosomatic

_ appendages. In the thyroid gland we again see a ductless
gland of immense importance to the economy, not a useless

organ, but, like the other modified coxal glands, impossible to.
remove without far-reaching vital consequences. Such gland,
on the theory,) was in the arthropod a part of the external
genital ducts which opened on the basal joint of the operculum,
What, then, is the opinion of morphologists as to the meaning

of these external genital ducts ?

_ Ina note to Gulland’s paper? on the coxal glands of Limulus,
Lankester states* that the conversion of an externally opening
tubular gland (coxal gland) into a ductless gland is the same kind
of thing as the history of the development of the suprarenal from
a modified portion of mesonephros, as given by Weldon. Further,

that in other arthropods with glands of a tubular character open-
-ing to the exterior at the base of the appendages we also have
coxal nephridia, such as the shell glands of the Entomostraca,

green glands of Crustacea (antennary coxal gland); and further
on* he writes, “when once the notion is admitted that ducts.
opening at the base of limbs in the Arthropoda are possibly and
even probably modified nephridia, we immediately conceive the.
hypothesis that the genital ducts of the Arthropoda are modi-
fied nephridia.”

So also Korschelt and Heider,> in their general summing up.
on the Arthropoda, say :-—

“In Peripatus, where the nephridia appear, as in the Annelida,

in all the trunk segments, a considerable portion of the primitive

segments is directly utilised for the formation of the nephridia.

In the other groups, the whole question of the rise of the organs
known as nephridia is still undecided, but it may be mentioned

as very probable that the salivary and anal glands of Peripatus,.
the antennal and shell glands of the Crustacea, the coxal glands
of Limulus and the Arachnida, as well as the efferent genital

1 Part LV. of this series of papers, This Jowrnal, vol, xxxiii. p. 638,

2 ** Bvidence in favour of the view that the coxal gland of Limulus and of
other Arachnids is a modified Ay cat by G. Gulland, Q. J. Mier. Sci., vol.
xxv. p. 511, 1885.

* Op. ecit., p. 515, * Ibid., p. 516,

a Teztt-book of Embryology, —Invertebrates, part iii. p. 423,

216 DR WALTER H. GASKELL.

ducts, are derived from nephridia, and in any case are mesodermal
in origin.”

The necessary corollary to this exceedingly probable argu-
ment is that glandular structures such as the uterine glands of
the scorpion already described, which are found in connection
with these terminal genital ducts, may be classed as modified
nephridial glands, and that therefore the thyroid gland of
Ammocecetes, which, on the theory of these papers, arose in
connection with the opercular genital ducts of the Palostracan
ancestor, represents the coxal glands of this fused pair of
appendages. Such a gland, although its function in connection
with the genital organs had long disappeared, still, in virtue of
its original excretory function, persisted, and even in the higher
vertebrates, after it had lost all semblance of its former structure
and become a ductless gland of an apparently rudimentary
nature, still, by its excretory function, demonstrates its vital
importance even to the highest vertebrate.

By this simple explanation we see how all these hitherto
mysterious ductless glands, pituitary, thymus, tonsils, thyroid,
are all accounted for, are all members of a common stock—
coxal glands—which originally, as in Peripatus, excreted at the
base of the prosomatic and mesosomatic appendages, all retained
because of the importance of the excretory function, although
ductless, owing to the modification of their original appendages.

Finally, there is yet another organ in the vertebrate which
follows the same law of the conversion of an excretory organ
into a lymphatic organ when its connection with the exterior
is obliterated, and that is the vertebrate body cavity itself.
According to the scheme here put forth, the body cavity of the
vertebrate arose by the fusion of a ventral prolongation of the
original nephrocele on each side; prolongations which accom-
panied the formation of the new ventral midgut, and by their
fusion formed originally a pair of cavities along the whole length
of the abdomen, being separated from each other by the ventral
mesentery of the gut. Subsequently, by the ventral fusion of
these two cavities, the “_— cavity of the adult vertebrate was
formed.

This is simply a statement of the known method of formation

Part IV, of. this series of papers, 7his Jowrnal,-vol. xxxiii. p. 654,

a ee

> <a"

ORIGIN OF VERTEBRATES. 217

of the body cavity in the embryo; and its phylogenetic ex-
planation is, that the body cavity of the vertebrate must be
looked upon as a ventral prolongation of the original ancestral
body cavity. Embryology clearly teaches that the original
body cavity or somite was confined to the region of the
notochord and central nervous system, and there, just as in
Peripatus, was divisible into a dorsal part, giving origin to the
myoceele, and a ventral part, forming the nephrocele. From
this original nephroceele are formed the pronephric excretory
organs, the mesonephric excretory organs, and the body
cavity. .

That the vertebrate body cavity was originally a nephrocele
is generally accepted, and its excretory function is shown by
the fact that it communicates with the exterior in all the
lower vertebrates, either through abdominal pores or by way
of nephridial funnels. Bles? has shown how largely these
two methods of communicating with the exterior mutually
exclude each other. In the higher vertebrates both channels
become closed, except in the case of the Fallopian tubes, and
thus, so to speak, the body cavity becomes a ductless gland,
still, however, with an excretory function, but now, as in all
other cases, forming a part of the lymphatic rather than of the
true excretory system.

CONCLUSIONS.

The consideration of the formation of the vertebrate cranial
region, as set forth in the previous ten parts of this series of
papers, indicates that the ancestor of the vertebrates was not
an arachnid purely or a crustacean purely, but possessed partly
crustacean and partly arachnid characters. In order to express
this conclusion, I have used the term Protostraca, invented by
Korschelt and Heider, to indicate a primitive arthropod group
from which both arachnids and crustaceans may be supposed to
have arisen, and have therefore stated that the vertebrate did
not arise directly from the annelids, but from the Protostraca.
Such an origin signifies that the origin of the excretory organs

1 “On the openings in the wall of the body cavity of Vertebrates,” by E. J.
Rles, Proc. Roy. Soc., vol. 62, p. 232, 1897.
VOL. XXXVII. (N.S. VOL. XVIL.)—JAN. 1903. 15

218 DR WALTER H. GASKELL.

of the vertebrate must not be looked for in the segmental organs
of the annelid, but rather in such modified annelid organs as would
naturally exist in a primitive arthropod group. The nature of
such organs may be inferred owing to the fortunate circumstance
that so primitive an arthropod as Peripatus still exists, and we
may conclude that the protostracan ancestor possessed in every
segment a pair of appendages and a pair of coelomic cavities
which extended into the base of these appendages. The ventral
portion of these ccelomic cavities separated off from the dorsal
and formed a nephroceele, giving origin to a segmental exeretory
organ, which, seeing that its end vesicle was in the base of the
appendage, and seeing aiso the nature of the known arachnid
and crustacean excretory organs, may fitly be termed a coxal
gland.. This, then, is the working hypothesis to explain the
difficulties connected with the origin of the pronephros and
mesonephros—that the original’ segmental organs were coxal
glands, and therefore indicated the presence of appendages.
This hypothesis leads to the following conclusions :—

1..The coxal glands belonging to the post-branchial appendages
of the invertebrate ancestor are represented by the pronephrie
tubules, and existed over the whole metasomatic region.

2. Such glands discharged into a common duct—the pronephric
duct—which opened into the cloacal region, either in the
protostracan stage, when the metasomatic appendages were still
in existence, just as the coxal glands of the prosomatic region in
Limulus discharge into a common duct, or else the pronephric
duct was formed when the appendages were obliterated. .

3. The metasomatic appendages disappeared owing to their
enclosure by pleural folds, which, meeting in the mid-ventral
line, not only caused the obliteration of the appendages, and gave
a smooth fish-like body surface to the animal, but also caused
the formation of an atrial cavity.

4, Into these pleural folds the dorsal longitudinal muscles of
the body extended, and ultimately reached to the ventral surface,
thus forming the somatic muscles of the vertebrate body.

5. When the pleural folds had met in the mid-ventral line
the animal had become a vertebrate, and was dependent for its
locomotion on the movements of these somatic muscles, and. not
on the movements of appendages. Consequently, elongation of

ORIGIN OF VERTEBRATES. 219

the trunk region took place, for the purpose of increasing
mobility, by the formation of new metameres.

6. Each of such metameres possessed its own segmental
excretory organ, formed in the same way as the previous
pronephric organs, but, as there were no appendages in these
new formed segments, the excretory organs took on the characters
of a mesonephros, not of a pronephros, and opened into the
pronephric duct, because the direct way to the exterior was
blocked by the enveloping pleural folds.

7. The group of annelids from which the protostracan ancestor
of the vertebrates arose was the highest annelidan group, viz.,
the Polychzta, as shown by the nature of the excretory organs
in Amphioxus.

8. The coxal glands of the protostracan ancestor existed on
all the segments, and were therefore divisible into three groups,
prosomatic, mesosomatic, and metasomatic; these three groups of
coxal glands still exist in the vertebrate as ductless glands.

9. The prosomatic coxal glands form the pituitary body.

10. The mesosomatic coxal glands form the thymus, thyroid,
parathyroids, tonsils, etc.

11. The metasomatic coxal glands form the adrenals.

12. The proceelom of the vertebrate is the proceelom of the
protostracan ancestor, which splits into a dorsal part, the
myoceele, and a ventral part, the nephroceele. This latter part
not only forms the pronephros and mesonephros, but also by
a ventral extension gives origin to the walls of the vertebrate
body cavity or metaccele.

13. This ventral extension of the original nephroceele at first
excreted to the exterior through abdominal pores or through
peritoneal funnels. When such paths to the exterior became
closed, it also became a ductless gland, belonging to the lymphatic

system.

CamBrince, May 1902.

gs aie
a pageant 0 MR 2

| Gournal of Anatomy and. Physiology.

a ON THE DEVELOPMENT AND HOMOLOGY OF THE
_ MAMMALIAN CEREBELLAR FISSURES By O.
ed _ Cmarnock Bravery, M.B., Professor of Anatomy, . Royal
Veterinary College, Edinburgh. (PLates XVIL-XXIIL)

Part. IT.—Pie.

40 days embryo, 52 mm. long (figs. 54,55 and 56). —At this
stage the cerebellum of the pig embryo bears a certain likeness
to that of the rabbit on the 20th day of gestation. No fissures
visible to the naked eye, but when sections are made and
pically examined there is noticed a somewhat thin lip-
like plate projecting from the lower posterior corner of the
section of the cerebellar lamina (fig. 56). This is comparable

-s every respect to the same feature in the rabbit’s brain on
the 20th day, and there develops a homologous lobe in con-
nection with it.
44 days embryo, 64 mm. . long (figs. 57, 58 and 59).—Develop-
- ment has proceeded rapidly during the interval between the
_ last stage and the present. A naked-eye examination shows a
Sufficiently clear distinction between the future vermis and

mispheres. There is also visible on the anterior slope a
fissure (II.) of considerable length (fig. 58). Microscopic sagittal
; , hacia show fissure IV. as before, and fissure II. of some depth.
Segew are also possibly faint indications of two other fissures
in that part of the vermis lying between IT. and IV. There is
_ as yet no trace of a separation of a paraflocculus from the
4 : S iainiaphore.
48 days embryo, 80 mm. long (figs. 60, 61 and 62).—Develop-
_ 1 The work, of which the present paper is the outcome, was done by the
__ writer as a Research Student of the University of Edinburgh.

__—~*VOL. XXXVII. (N.S. VOL. XVII.)—APRIL 1903, 16

222 PROFESSOR 0, CHARNOCK BRADLEY.

ment has again progressed rapidly; indeed, it is something of
a misfortune that a stage intermediate between 44 and 48 days
could not be obtained. But though this is a misfortune, it is
not one which offers any insuperable difficulty in the solution
of the problem before us.

An examination of a 48 days cerebellum reveals a fissure (II.)
which is prolonged for some distance into the hemisphere.
Below it the two other fissures are faintly marked. These
develop into fissures I. and ¢«. On the posterior slope there
are two faint fissures in the vermis. Subsequent development
shows that these become fissures III. and d. In the hemisphere
there is an indication of a fissure, which, growing inwards from
the lateral part of this portion of the cerebellum, ultimately
demarcates the paraflocculus. Another faint foreshadowing of
a fissure is also seen indenting the margin of the hemisphere
anterior to the one just mentioned. This latter, growing in-
wards, ultimately forms part of fissure a (fig. 60, a).

Microscopic sections afford additional evidence as to the
actuality of the faint depressions seen with the naked eye
(fig. 62). They also show that a number of fissures are about
to complicate that portion of lobe A which lies below fissure ¢
(lobule A,). Lobe E has increased in volume, and is now, in
consequence, sharply defined from the posterior medullary
velum. A flocculus is becoming evident, and its development
from the boundary of the lateral recess is clearly indicated. Its
boundaries are not as yet rigidly set down, but it reveals itself
as a thickening and bulging in the region in which, in the
future, it is to become conspicuous (fig. 61).

Embryo, 86 mm. long—In the cerebellum of an embryo of
86 mm. in length (of which the age is not certainly known,
but is estimated at about 50 days) the anterior surface is quite
richly fissured. Fissure II. now reaches the extreme margin of
the hemisphere, and fissure I. almost does so. On the posterior
slope, fissure a runs completely across the cerebellum, but is
shallow at the junction of vermis and hemisphere. Fissure ILI.
crosses the vermis and invades the groove between it and the
hemisphere.» The fissure which is about to cut off the para-
flocculus is deep, and is growing inwards towards fissure III.
of the vermis, with which it finally becomes continuous.

THE MAMMALIAN CEREBELLAR FISSURES. 223

_ Fissure d is, if anything, rather longer than fissure III. The
paraflocculus forms a distinct projection, and is now clearly
separated from the flocculus. Sections show that lobe B is
becoming divided by a shallow transverse fissure.

51 days embryo, 88 mm. long (figs. 63, 64 and 65).—The
difference between this and the above stage is only one of depth
of fissures.

55 days embryo, 100 mm. long (fig. 66)—To the naked eye
the fissures have obviously deepened since the 51st day, but no
new ones can be made out. Sections, however, show that a
fissure, 6, has begun to invade that part of lobe C which is in
the vermis. It seems likely that this fissure first made its
appearance, on the anterior slope of the hemisphere, about the
48th day (fig. 61), and that the two parts gradually grew
together in the vermis. It is interesting to notice at what
an early period fissure a came into existence, and how com-
paratively late fissure } is in making its appearance in the
vermis. This should be compared with the constancy of the
former fissure in the cerebella of the type of the rabbit, and
the inconstancy or difficulty of determination of fissure 0 in
the cerebella of the same order of complexity.

The fissures in lobule A, are now of considerable depth.

Lobule A, retains its comparatively small size. Lobe B is
larger, and contains a moderately deep fissure, which is the
_ forerunner of a like feature in the adult brain.
59 days embryo, 118 mm. long (figs. 67, 68 and 69).—As in
the rabbit, the anterior part of the pig’s cerebellum has advanced
more rapidly than the posterior part during the earlier stages
of development. By the 59th day the anterior surface is bear-
ing a strong resemblance to the adult condition, but the
_ posterior part is still comparatively simple. Fissure } is now
_ of some depth and can readily be recognised by the unaided eye.
Fissure a has gained considerably in depth. Fissure III. has
become continuous with the lateral fissures, which, making an
early appearance, first indicated the limits of the paraflocculus.

Fissure is of great lateral extent, being indeed the longest
fissure of the cerebellum at this stage (with the possible
doubtful exception of fissure IL, which has a curved course).
Fissure d, it should be noted, is growing forwards into the

224 PROFESSOR 0. CHARNOCK BRADLEY.

paraflocculus, which is, by it, being divided into an upper and
a lower part, connected together in front (fig, 67). It is desired
to emphasise the fact that there is a strong, well marked
connection between lobe D and the parafloceulus. This
connection at this stage is not confined to the part of lobe D
above fissure d (lobule D,), but belongs to the entire lobe.
Nothing could show more clearly that the parafloceulus and
lobe D are parts of one and the same morphologic unit. This
point is illustrated much better in the pig than it was in the
rabbit.

The paraflocculus has enlarged, and its anterior surface shows
signs of foliation (fig. 68).

65 days embryo, 132 mm. long (figs. 70, 71, 72, 73 and 74).—
The anterior surface has now very closely approached the adult
condition, both in its external appearance and also in those
features which can only be adequately appreciated by means
of sagittal sections.

Fissure II. is of great depth, its lowest part being not far
removed from the summit of the roof of the 4th ventricle
(fig. 74). Lobe B shows definite evidence of its future bipartite
condition. Lobule A, has now lost its former arrangement of
indefinitely arranged folia, and has collected them into three
sub-lobules such as are found in the adult brain. Fissure 0
is now of some depth, and fissure a makes an important
landmark on the posterior slope. Fissure d is deeper than
fissure III, and both parts of lobe D are becoming foliated
(fig. 74). Lobe E remains relatively small and simple, but
is now separated from the posterior medullary velum by a
conspicuous fissure.

The paraflocculus is now divided into two parts, both of
which are now foliated. The whole lobule now closely
resembles the same lobule in the adult squirrel. The division
into two parts has obviously been brought about by an ex-
tension in a forward direction of fissure d. This extension
was beginning in the previous stage. The upper part of the
paraflocculus is connected with lobule D, by a rounded non-
foliated ridge. The connection between lobule D, and the
lower half of the paraflocculus has almost become obliterated,
but it should be kept in mind that such a connection did at

eae
+
+x
ag

THE MAMMALIAN CEREBELLAR FISSURES. 225

one time exist. The flocculus is small and, to the naked eye,

not yet provided with folia. On examining microscopic sections,

. however, slight fissures are found to exist.

70 days embryo, 150 mm. long (fig. 75)—Except in richness
of foliation, no marked change has occurred in that part of the
cerebellum which is anterior to fissure II.. The posterior
portion of the organ, however, has now entered into a more
active phase of development, and is rapidly assuming the adult
appearance. That part of lobe C which is anterior to fissure a
(lobules C, and C,) has grown considerably in a lateral
direction. Further, the vermis portion has also grown so much
in an antero-posterior direction that it can no longer be
accommodated in the strict mesial plane, but has become
distorted by being thrust over to one side. Fissure 6 is now
a very important feature. It extends all the way across the
cerebellum. Lobule C, has also altered considerably in appear-
ance. It no longer forms a band of practically uniform width,

_Tunning from one margin of the cerebellum to the other. It

now fails to extend as far laterally as the more anterior part
of lobe C. Its vermis portion has increased in volume in a
sagittal direction, and, like that part of the vermis immediately
in front of it, is now distorted by being pushed to one side.
The hemisphere portions, too, have enlarged in a sagittal
direction, and are now in the form of rounded masses, connected
with the vermis by a comparatively narrow isthmus. This
lobule has therefore come to resemble that of the squirrel.
‘The two parts of lobe D have also enlarged, and their folia

_ are more numerous. The connection between lobule D, and
_ the corresponding part of the paraflocculus is still smooth.

Lobe E remains small, and to the naked eye appears to have

" no connection with the flocculus beyond that established by

means of the posterior medullary velum. But microscopic
sections show that there is still a low smooth ridge running

E between the two structures.

The paraflocculus has not increased much in size, and,

2 because of the lateral expansion of lobe C, is now not so

prominent a feature on the lateral surface of the hemisphere.
The flocculus is still small, and to the naked eye smooth.
_ Embryo, 165 mm. long, age unknown (figs. 76, 77, 78, 79

226 PROFESSOR O. CHARNOCK BRADLEY.

and 80).—This is the last embryonic stage which it is necessary
to examine, as it brings us within a short distance of the
condition of the adult cerebellum. Lobule A, is now certainly
composed of three sub-lobules, the uppermost of which has
beyond doubt an extension into the hemisphere. One single
small folium still adheres to the anterior medullary velum,
and therefore may possibly be looked upon as an attenuated
example of a lingula. Lobule A, is relatively small, and has a
rather shallow fissure dividing it into two parts. Fissure II.
begins on the dorsal surface of the vermis; curving forwards
at the lateral boundary of the vermis, it runs obliquely down
the anterior surface. Lobe B is divided into upper and lower
portions by a fairly deep fissure, whose advent has been noted
in earlier stages. Lobe C has again made great advances. So
much is this the case that lobule C, is very considerably
distorted. Lobule C, is now clearly divided into three parts—
one in the vermis and one in each hemisphere—connected by
narrow bands. The connection between lobule D, and the
upper part of the paraflocculus is becoming slightly marked
by fissures, and has become in part hidden by the posterior
extremity of lobe C.

The paraflocculus is now quite complicated, from the presence
of numerous folia; but there is no difficulty in recognising its
constitution as two tiers. The flocculus is now foliated.

Adult cerebellum (figs. 81, 82, 83 and 84).—Having traced
the development of the fissures and lobes up to an advanced
stage, it does not seem necessary to give an additional detailed
description of the adult organ. It will suffice to briefly indicate
the changes which have occurred since the 165 mm. stage.

The cerebellum anterior to fissure II. has not undergone any
radical change. It has taken additional folia upon itself, but
that is all. In the posterior part of the cerebellum more
decided changes have occurred. Fissure } is now very distinct
crossing vermis and hemisphere, and reaching the border of the
latter. A further displacement of the vermis portion of lobe
C has taken place, so that in the adult brain fissure @ is
decidedly oblique. The connections between the vermis and
hemisphere portions of lobule C, have become very much reduced.
The upper part of lobe D has shared in the general distortion of

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THE MAMMALIAN CEREBELLAR FISSURES. 227

this region of the vermis. Its connection with the paraflocculus
now consists of a transversely foliated ridge (fig. 83). Lobule
D, has merely increased in size and become more thickly foliated.
Lobe E remains very small and inconspicuous (tig. 84).

In many cerebella the paraflocculus has become a somewhat
jumbled collection of folia, but in most brains it has retained
a closer resemblance to its earlier condition. There is usually
little difficulty in tracing its two-tiered character, but it appears
as though the lower tier had been turned forwards at its pos-
terior end. The flocculus in the adult is in the form of a row
of vertically placed folia, and runs in an antero-posterior direc-
tion, immediately below the paraflocculus. Its extremities only

are visible when the cerebellum is looked at from before or from

behind.

Having now learnt the characters of the fissures and lobes in
the pig, we are in a position to examine those cerebella which are
constructed after a similar plan.

Mustela furo (figs. 85, 86, 87 and 88)—In this animal is
a good example of the backward retreat that fissure II. makes in
some of the more complex cerebella. The vermis is about
equally voluminous in front of and behind this fissure, this

being the result of an increase in the number of lobules in the

more anterior section of the vermis.

Lobe A is divided into two slightly unequal parts by a fissure,
¢, which is almost entirely visible when the cerebellum is looked
at from the front, and which reaches the margin of the hemi-
sphere. Lobule A, is divided into two parts, each carrying two
or three folia. Lobule A, is also divided into two portions, but
the fissure is not so deep as that in lobule A,. . Lobe B is cut
by a curved fissure which almost reaches its lateral boundaries.
It will be seen that lobes A and B are very similar to the
corresponding lobes in the pig, except that the lower component
of A is divided into two instead of three sub-lobules.

Lobe C forms a very considerable constituent of the hemi-
sphere. It has fissures a and 8, but the lobules in the vermis
between a and d and a and III. are comparatively simple; «a.
they are not developed to such an extent that their accommoda-
tion necessitates distortion of the vermis. The connection
between vermis and hemisphere segments of lobule C, is very

228 PROFESSOR 0. CHARNOCK BRADLEY.

narrow, as in the pig, and partly or wholly concealed. Lobes
D and E are confined to the vermis; and D is divided into two
lobules by a fissure, d.

The paraflocculus is arranged in the form of two tiers of folia
joined together anteriorly. From the lower tier a lobulus
petrosus projects for some distance. The connection between

-paraflocculus and lobe D cannot be made out in the adult. It is

somewhat difficult to satisfactorily distinguish a flocculus, but
it is apparently present, and visible when the cerebellum is
viewed from the side or from behind.

Mustela erminea and M. vulgaris have both been examined,
but they so closely resemble MZ. furo that no further description
is necessary.

Meles taxus (figs. 89, 90, 91 and 92)—As compared with
lobe B, lobe A is smaller in the badger than it is in the
pig. Only a comparatively small portion of it is visible on
the anterior surface of the cerebellum. Lobule A, is also small.
Below fissure ¢ there are two groups of folia, that group lying
more inferiorly being further partially divided.

Lobe B is large, and divided by a deep fissure into upper and
lower lobules, each of which is again somewhat deeply indented
by a fissure (fig. 92).

In lobe C, fissure 6 extends to the border of the hemisphere,
as it does in the pig (fig. 90). Lobule C, consists of a vermis

portion, whose folia—unlike those of the pig—run transversely ;

and a hemisphere part, considerably removed from the vermis,
because of the large development of those parts of lobule ©,
which belong to the hemisphere. The three segments of lobule
C, are very unequal in size, the hemisphere portions being
very extensive. There is practically no distortion of lobule C,
in the vermis (fig. 91). Lobes D and E call for no special remark.
The double character of the paraflocculus is very evident, the
two portions being arranged in an oblique plane, and very
clearly continuous in front (figs. 89 and 90). The connection
between paraflocculus and vermis is very difficult to establish.
In the brain examined, a very prominent lobulus petrosus was
present on the right side, and was received into a fossa formed
by the temporal bone. On the left side the corresponding
lobule was curved forwards underneath the lower part of the

EE ee a a

THE MAMMALIAN CEREBELLAR FISSURES. 925

paraflocculus (fig. 89). The question arises as to the possibility
of the lobulus petrosus always representing the posterior
extremity of the lower portion of the paraflocculus. This may
be the case. If we accept this as being a true interpretation
of the facts, then we should consider that, as the paraflocculus
inereases in size in different animals, it tends to press forwards,
since the lobulus petrosus is often found in cerebella having
small paraflocculi.

The flocculus consists of a single folium lying between the
lateral recess of the ventricle and the most posterior part of the
paraflocculus. é

Canis familiaris (figs. 93, 94, 95 and 96).—The anterior
part of the cerebellum of the dog does not differ very materially
in the arrangement of its fissures and the disposition of its lobes
from the corresponding part of the badger’s cerebellum. In
lobes C and D, however, there are differences of sufficient
magnitude to warrant mention. Fissure 0 is present in a position
very similar to that of the badger. It can readily be followed
across the vermis and hemisphere to the border of the latter,
running almost parallel to fissure II. Lobule C, has a very
considerably distorted vermis portion, and its hemisphere
dependencies show several fissures of some depth, which give
the impression that it consists of several distinct sub-lobules.
The central segment of lobule C, is also much twisted, and on
superficial examination appears to have no connection with
those vertically elongated masses which form its hemisphere
segments. On opening up the groove between vermis and
hemisphere, however, the connection can be distinguished. The
displacement and sinuousness of the vermis in lobules C, and
C, only appears after birth. In a new-born dog the vermis is
perfectly straight and its folia entirely transverse.

Lobule D is connected to the upper part of the paraflocculus
by a low white ridge, which can only be discovered by removing
the lowest and most posterior part of lobe C. The rest of lobe

D and lobe E call for no remark.

' _ The paraflocculus is relatively larger than that of the badger,
to which it bears a close resemblance in the manner in which
its two tiers are arranged. It has not, however, a lobulus
petrosus; or, at any rate, there is not more than the merest

230 PROFESSOR 0. CHARNOCK BRADLEY.

attempt at the formation of one, this occurring at the posterior
end of the lower tier, and being only occasionally present. The
flocculus is small and consists of a few folia, placed, under cover
of the paraflocculus, at the most anterior limit of the lateral
recess of the ventricle (fig. 95).

Canis vulpes (figs. 97, 98 and 99).—The general shape of the
cerebellum of the fox is very different from that found in the
dog. The fox’s cerebellum has a greater vertical height in com-
parison with its antero-posterior diameter. Its anterior surface
is depressed for the reception of the corpora quadrigemina, and
its posterior surface is also concave from above downwards.
The posterior concavity is rendered all the more obvious because
of the backward projection of lobe D over the medulla, This
projection is confined to lobule D,, and is so great that this
lobule can be seen very distinctly when the cerebellum is
viewed from above. These differences being recognised, the
cerebellum of the fox otherwise resembles that of the dog.
The only points to which it seems necessary to draw attention
are two, as follows: The vermis in the region of lobules C,
and C, is possibly a little shorter in an antero-posterior
direction, and somewhat less distorted in form. The lower
part of the paraflocculus carries a definite lobulus petrosus
(figs. 97 and 98),

The flocculus is small in the fox, and only just visible from
behind (fig. 98).

Felis domestica (figs. 100, 101 and 102).—In the domestic cat
the anterior part of the cerebellum is so similar to the same
portion in the dog, both as regards its superficial characters and
also its appearance in sections, that no detailed description is
needed. The most important features are those presented by
the organ when viewed from behind. Several cerebella of the
cat have been examined, and in all a very striking character is
the extreme to which the distortion of the central portions of
lobules C, and C, is carried (figs. 100 and 101). In the brain
from which the figures were made this distortion is very
marked, possibly more so than is the case in the average cere-
bellum; but they serve to show to what lengths this twisting
of the vermis may go. It will be observed that lobules C, and
C, are arranged in the form of an S-shaped curve, the bends of

THE MAMMALIAN CEREBELLAR FISSURES, 231

which are very abrupt. This curvature of the vermis is con-
tinued into lobe D, but here its bends are not so sudden (fig:
101). There can be little doubt that this exaggerated dis-
placement of the vermis is to be interpreted as meaning that,
in the cat, lobes C and D are relatively more developed (so
far as those parts of them which belong to the vermis are con-
cerned) than is the case in the other mammals examined. The
lateral parts of lobule C, are relatively smaller in the cat than
in the dog, badger, or fox (fig. 101). They do not extend so
far downwards as to blot out the connection between para-
flocculus and the vermis. This connection is in the form of
one or two folia, resting upon the medulla below, and in con-
tact with the lowest part of lobule C, above.

The paraflocculus resembles that structure in the dog. There
is considerable difficulty in distinguishing a flocculus with any
degree of certainty in the adult animal. That it is present is
undoubted from the observations made by Stroud on its
development. But its clear definition in the embryo appears
to become obscured at a later date.

Goat and Sheep (figs. 103, 104 and 105).—In many respects
the cerebellum of ungulates departs, in the way of details,
from the plan found in those carnivora just described.

When viewed from the front, the cerebella of the goat and
sheep show fissures c, I., II. and } very distinctly (fig. 103), all
of these reaching the margins of the hemisphere. Fissure c¢
erosses the vermis almost perfectly transversely. Lobule A,
has only a very imperfectly developed hemisphere portion ;
indeed it is doubtful if the hemispheres can be considered to
extend into this region. Fissure I, possibly a little shallower
than c, has a curved direction. Fissure II. is very acutely
curved, as in the dog. Lobule A, and lobe B are almost entirely
confined to the vermis, their lateral prolongations being very
small. Indeed, in this region it is difficult to set definite bounds
between the vermis and the hemispheres. There is some
amount of lateral displacement, with consequent curvature, in
the vermis in lobules C, and C,, but this is not greater in
amount than that found in the dog.

In the sheep and goat, and in ungulates generally, the lateral
divisions of lobule C, are not nearly so large as they are in the

232 PROFESSOR 0. CHARNOCK BRADLEY

carnivora. In the carnivora their uppermost ends are commonly
visible, either on one or both sides, when the cerebellum is
regarded from the front. This has never been found to obtain
in those ungulates which have been examined for the purposes
of this research. Again, these lobules do not reach so far down
as to touch the medulla, other than in exceptional cases. The
result of this vertical abbreviation is to allow of the connection
of the paraflocculus to be traced directly to the vermis, as is
the case in the simpler forms of cerebellum (fig. 104). As we
have seen, this connection is easily made’ out in the adult pig.
In the sheep and goat, however, it is not quite so evident on a
superficial examination; it is necessary to open up the groove
between vermis and hemisphere.

The form of lobule D, is somewhat peculiar in both the sheep
and goat (fig. 104). It has a central, well developed portion in
the vermis, and smaller offshoots reaching into the hemispheres,
a constriction of greater or less tenuity intervening.

Lobe E is of larger size than in the pig and the carnivora.
The paraflocculus and flocculus resemble those parts of the
cerebellum of the pig.

Bos tawrus (fig. 106).—In the cerebellum of the cow, although
the same lines are followed as in the sheep and goat, the arrange-
ment of fissures appears at first sight to be very complicated.
This remark applies only to the superior and posterior views,
as lobes A and B and lobule C, are almost identical in form
with those parts in the average carnivore or ungulate brain. It
may be added that it is impossible to make out any hemisphere
in lobe A. Even in lobe B the hemisphere is very attenuated.

On closely examining the posterior part of the cerebellum, it
is found that the complexity is more apparent than real, and is
due to a distortion which rivals that of the cat’s vermis. Apart
from this disturbance of form, there is little to which special
attention need be directed. It may be mentioned, however,
that the lateral parts of lobule C, commonly extend farther in
a downward direction than obtains in the sheep and goat, this
extension bringing them almost or quite in contact with the
medulla. Not infrequently lobe E is so large and projects so
far backwards as to be visible as one or two folia on the pos-
terior aspect of the cerebellum.

a | ey

so

THE MAMMALIAN CEREBELLAR FISSURES. 233

| _ Equus caballus (figs. 107, 108 and 109)—A very striking

feature in the horse’s cerebellum is the comparatively posterior
position of fissure II. Fissures ¢, I., II. and 6 are distinct and
deep. Fissure ¢ is of very considerable depth, and fissure I. is
almost as deep as fissure II. (fig. 109). It should be noted—as
distinguishing the cerebellum of the horse from that of the
sheep and goat, and especially from that of the cow—that lobe
A is certainly, though not very strongly, continued into the
hemisphere.

The posterior part of the horse’s cerebellum shows one or
two points of interest and importance. As in the ungulates
already mentioned, the lateral parts of lobule C,; are small as
compared with the carnivora. In the horse their connections
with the vermis are not difficult to follow. There is, further,
no difficulty in making out the connecting link between lobule
D, and the paraflocculus (fig. 108).

In some specimens lobule D, is continued into the hemi-
sphere for a short distance, but this continuation has only once
been found on both sides in the same brain. Its presence,
though inconstant, is interesting, as being apparently the
remains of that undoubted connection which we have seen to
exist between lobule D, and the lower part of the paraflocculus
during the embryonic life of the pig. In the majority of
animals all trace of this primitive unity is lost as the brain
grows into its adult form; but in some, possibly in man, evi-
dences remain.

Lobule E is, if anything, smaller in the horse than it is in
the sheep, goat and cow. The paraflocculus shows its two-tier
character more clearly than in the other ungulates examined,
in this respect resembling the paraflocculus of the carnivora.
It should be remembered that in ungulates generally the lower
tier shows a tendency to curve forwards at its posterior end.
This is so well marked in the horse that there are practically

‘three tiers produced. In an earlier part of this paper the sugges-

tion has been thrown out that possibly the lobulus petrosus of

the rabbit, etc. represents only the posterior extremity of the

lower part of the paraflocculus of more complex cerebella. It may
be asked, further, whether in those animals like the horse, in
which the paraflocculus turns forwards at its posterior end, this

234 PROFESSOR 0, CHARNOCK BRADLEY.

recurved extremity may not be equivalent to a lobulus petrosus,
unenclosed in a special fossa of bone. The supposition that this
may be so is strengthened when the condition found in the badger
is taken into account. In the cerebellum of Meles taxus, of
which a description has already been given, on one side a lobulus
petrosus was found; but on the other side the corresponding
part of the paraflocculus was turned forwards underneath the
lower tier.

The flocculus is usually easily distinguished in the horse, and
is visible from the side and from behind. In some specimens
a distinct white ridge, independent of the posterior medullary
velum, passes from the flocculus to lobe E of the vermis. This
ridge is indicated on the left side of fig. 108. It has not been
met with elsewhere than in the horse—possibly because an
insufficient number of cerebella have been examined—but its
occurrence in this animal is of importance, as showing evidence,
in the adult, of the embryonic unity of the structures between
which it passes.

Equus asinus.—The cerebellum of the donkey is so like that
of the horse in all but the merest details that an extended
description is not necessary. It may perhaps be well to say
that lobule C, in the hemisphere carries several fairly deep
fissures, whose presence give the surface a complex appearance.
Lobule D, shows the tendency, remarked in the sheep and goat,
to extend into the hemispheres in the form of lateral append-
ages. The connection of this lobule with the paraflocculus is
not so superficially evident as it is in the horse. The flocculus
of the donkey has a greater antero-posterior extent than is the
case in the horse.

In the foregoing pages the steps by which the fissures, and
consequent lobes and lobules, of the cerebellum came into
existence have been traced in two mammals. It has also been
sought to discover the simplest form of mammalian cerebellum,
and this having been done, to endeavour to recognise, in the
complex as well as in the simpler forms, a likeness to this
elementary pattern. Apparently the cerebellum in which the
fissures are fewest. and the lobes smoothest belongs to the
shrew and the smaller bats. In the shrew there are four

——— _—

eee

THE MAMMALIAN CEREBELLAR FISSURES. 235

fissures only ; and of these only one (the second, i.e. II.) extends
through both vermis and hemisphere. The remaining three do
not belong to the hemisphere, being confined to the vermis or
its immediate neighbourhood.

In following the development of the cerebellum of the rabbit,
it was found that this five-lobed and four-fissured stage was
reproduced. But in the adult rabbit the number of fissures is
increased. In the development of the pig, it appears possible
that the five-lobed condition may obtain in its simple form for
a time, but it quickly gives place to a much greater complex of
fissures.

In both rabbit and pig fissure IV. was the first to appear,
and this in association with the Rautenlippe, which, continuing
round the lateral recess of the ventricle, blends with the
Rautenlippe of the medulla. The association of fissure IV.
originally seems beyond doubt. But as development goes on it
becomes more and more removed from the edge of the cerebellar
lamina, because of the growth of lobe E and the flocculus.

In both rabbit and pig the second fissure to develop is
fissure II., which has been recognised by several writers to be
of paramount importance, and which is declared by both Stroud
and Kuithan to be the first fissure visible in the developing
cerebellum,

The next fissures, in point of time of appearance and impor-
tance as dividing lines of the cerebellum, are fissure III. and
those demarcating the paraflocculus from the rest of the hemi-
sphere. These three are in reality the three elements of one
and the same fissure, which, becoming continuous, they ultimately
form.

By the presence of the above mentioned fissures, the cerebellum
becomes divided transversely (but not completely as yet) into four
unequal portions. (1) A part anterior to fissure II.; this becom-
ing itself divided later into lobes A and B by fissure I. (2) Lobe
C, lying between fissure II. and fissure III., with its lateral
elements. (3) Lobe D, to which the paraflocculus belongs. And
(4) lobe E, of which the flocculus is an outlying dependency.

Fissure I., separating lobes A and B, appears shortly after
fissure III. in the rabbit,and somewhere about the same timein the
pig. The other fissures, which are formed either at the same time

236 PROFESSOR 0. CHARNOCK BRADLEY.

as some of the above (as in the pig), or at a somewhat later date
(as in the rabbit), may be considered as of secondary importance,
and have no representatives in the simplest type of mammalian
cerebellum.

In those adult cerebella which have been examined, there
is quite clearly a common pattern running through the whole
series. But in many of them there are interwoven into this
fundamental pattern subsidiary ornaments, which tend, in a
measure at least, to obscure the simplicity of the cere-
bellum which has been taken as the starting-point. In all the
cerebella the five fundamental lobes can be recognised, and
their individual peculiarities and tendencies may be summarised
as follows :—

Lobe A, in all but the very simplest forms, is divided into
two unequal parts by fissure ¢. This fissure is wanting in the
shrew and indefinite in the hedgehog, but is constant in all
others. Lobule A, in the higher forms consists of three sub-
lobules. In some there are apparently only two of these
divisions. It is possible that this complexity of the lobule may
be indicated even in the rabbit. Lobule A, is always smaller
than lobule A,, and is generally provided with a moderately
deep fissure, whose precursor may possibly be shown in the
rabbit.

In the higher forms lobe B is divided into two parts, each of
which may be again divided. In the rabbit and hedgehog it
carries two folia, separated by a moderately deep fissure.

Lobe C consists of three lobules, separated by fissures a and
b. Of these two fissures a is held to be much the more im-
portant morphologically, because of its earlier appearance in the
embryo and its more constant character in the adult. These
two fissures apparently develop in a manner peculiarly their
own. They both begin in the hemisphere, and grow towards
the middle line.

Lobule C, must be considered as standing definitely apart
from the rest of lobe C. Its differentiation is early, especially
in the pig, and in all the adult animals described, from the
squirrel upwards, its individuality is very strongly asserted.

Even in the rabbit there is an attempt at a division of lobe
D, but this is not accomplished until the squirrel is reached.

THE MAMMALIAN CEREBELLAR FISSURES. 237

In the higher forms the division is embryonic and early. In

the pig, fissure d appears about the same time as fissures III.
and I. Particular attention has been called to the develop-

_ ment of fissure d because of its forward extension and invasion

of the paraflocculus, which is, as a result, divided into two

parts, as is the rest of lobe D to which it belongs. Subsequent
development may obscure the continuity of the paraflocculus
with lobule D,, or, on the other hand, the connection may per-
sist into adult life (eg. in the horse). The connection of the

_ parafloeculus with lobule D, is always lost in the adult, but

_ there may remain slight traces, such as are found in the horse.

The embryonic continuity of lobe E and the flocculus, and
their morphologic unity, have already been commented upon.

_ This continuity early disappears, and there is usually no trace

of it apart from the posterior medullary velum. But in the

horse at least, as has been noted, some evidence may exist
even in the adult.

The various fissures and lobes have been distinguished, up to

_ this, by letters and figures only. It would have been easy to

_ employ terms such as those used in human anatomy, but—as

_ Oliver Wendell Holmes has expressed it—words, from occupy-

_ ing for a long time the same place in language, become

_ ‘polarized.’ So, in order to trammel the mind as little as

_ possible, it was thought better to avoid those terms which

_ would call up certain fixed and long-rooted conceptions.

___ The purpose of keeping the judgment as unbiassed as possible

_ being now served, the letters and figures may give place to

_ terms such as are commonly employed. In order to do this,

+ the notion of the plan of the mammalian cerebellum, which has

__ been gained from the descriptions given herein, must be applied

2 to the cerebellum of man. Using the technicalities as employed

__ by Schafer in Quain’s Anatomy, the letters and figures may be

_ transmuted as follows:

_ There can be little doubt that fissure II. corresponds to swleus
_ preclivalis, fissure III. to sulcus postpyramidalis, and fissure LV.
_ to suleus postnodularis. Fissures a and b correspond respectively

_ to sulei horizontalis magnus and postelivalis, and fissure d is

_ equivalent to suleus prepyramidalis. That sulcus horizontalis

magnus should not be employed, as is done in human anatomy,

VOL. XXXVII. (N.S. VOL. XVII.) —APRIL 1903. 17

238 PROFESSOR 0. CHARNOCK BRADLEY.

to divide the cerebellum into two primary parts, is evident, and
has been pointed out and insisted upon by Stroud. The com-
parative method clearly shows that sulcus preclivalis (fwreal
sulcus of Stroud) forms the real and fundamental dividing line.

In that part of the cerebellum which falls anterior to fissure
II. (suleus preclivalis), difficulties arise in the use of human
anatomical terms. For sulcus postcentralis of the human
anatomist corresponds to fissure ¢; a fissure secondary both in
point of time of appearance in the embryo and in morphologic
value. In the current deseriptions of the human brain, as
given in this country, no sulcus is mentioned as equivalent to
fissure I. The result is that the culmen of human anatomy
includes lobe B and lobule A,. Lobule A, probably corresponds
to the “ascending part of the monticulus” of some German
writers (Flatau and Jacobsohn, for instance), but I am not
certain that the expression is used for lobule A, alone or
always.

The following table shows the parts in the human brain
corresponding to the various divisions of the mammalian cere-
bellum as described in this paper.

FIssuRES. LOBES.

Lobus centralis,
c. Sulcus postcentralis

Lobus culminis,

I. (Not named by Schiffer)

II. Sulcus preclivalis

b. Sulcus postclivalis
Lobus cacuminis. C,.
a. Sulcus horizontalis magnus

Lobus tuberis. Cs.

III. Sulcus postpyramidalis,

|
:

Lobus pyramidis. — D,.
d. Sulcus prepyramidalis

Lobus uvule. D,..
IV. Sulcus postnodularis

Lobus noduli, } E. |

It will be observed that I have only examined the cerebella
of placental mammals. Lack of suitable material has precluded
a first-hand investigation of Monotremes and Marsupials. But,

THE MAMMALIAN CEREBELLAR FISSURES. * 239
judging from the descriptions and figures given by Ziehen (7),
it is clear that the scheme, as elaborated in the foregoing pages,
will apply to Marsupials at least. These mammals evidently
fall into the group of animals in which the cerebellum follows
the simpler type. Whether Monotremes also can be included
in this group is not so obvious from the descriptions available.
It seems not unlikely that their cerebella belong to a group
separate from the rest of the mammalia.

In -earrying out the work of this investigation, so much
assistance, in the form of material, has been afforded by so
many persons, that it is impossible to make suitable acknowledg-
ment without going to considerable length. Let it suffice to
say, that my debt of gratitude is not to be computed from the
extent of the avowal here made. Much of the microscopic
work has been done in the Physiological Laboratory of the
University of Edinburgh, where, through the courtesy of Professor
Schiifer and his assistants, every facility that could be wished
for has been afforded.

REFERENCE.

(7) Zimuen, Tu., ‘Das Centralnervensystem der Monotremen und
Marsupialier. Thiel I. Macroscopische Anatomie,” Jenaz’sche Denk-

schriften, vi., 1897.

PLATES XVII-XXIII.

EXPLANATION OF FIGURES.
Fig. 54. Pig embryo, 40 days, 52 mm, Posterior view. x 2.

Fig. 55. ce 40 days, 52mm. Left lateral view. x 2.
ig. 56. ie 40 days, 52mm. Mesial sagittal section.
Fig. 57. re 44 days, 64 mm. Posterior view. x 2.
Fig. 58. i 44 days, 64mm. Anterior view. x 2,
Fig. 59. Ss 44 days, 64 mm. Mesial sagittal section.
Fig. 60. | ‘ 48 days, 80 mm. Posterior view. x 2.
Fig. 61. a 48 days, 80 mm. Anterior view. x 2.

Fig. 62. - 48 days, 80 mm. Mesial sagittal section.
Fig. 63. i 51 days, 88 mm. Posterior view. x 2.
Fig. 64. a 51 days, 88mm, Anterior view, x 2.

THE MAMMALIAN CEREBELLAR. FISSURES.

. 65. Pig embryo, 51 days, 88 mm. — Mesial sagittal section.
66. - 55 days, 100 mm. Mesial sagittal section.

ig. 67. is 59 days, 118 mm. Superior posterior view. -
68. + 59 days, 118 mm: Anterior view. x 2.
ig. 69. » ~ 59 days, 118 mm. Mesial sagittal section.
ig, 70, 5 65 days, 132 mm. Posterior view. x 2.
71. Ss 65 days, 132 mm. Superior view. x 2
ig. 72. és 65 days, 132 mm. Anterior view. x 2.
ig. 73. os 65 days, 132 mm. Left lateral view. x 2.
ig. 74. 65 days, 132 mm. Mesial sagittal section. —
. 75. sj 70 days, 150 mm. Superior view. x 2.
. 76. ‘ 165 mm. Posterior view. x 2.
ig. 77. re 165 mm. Superior view. x 2.
78. 7 165 mm. Left lateral view. x 2.
ig. 79. ke 165 mm. Anterior view. x 2.
. 80. oy 165 mm. Mesial sagittal section.
ig. 81. Pig, adult. Anterior surface. x 1.
1g. 02>. 55 4s Superior view. x 1.
ig. 83. ,, +s Posterior view. x l.

ig. 84. ,, m Mesial sagittal section. x 1.

ig. 85. Mustela furo. Anterior surface. x 2
ig. 86. es Superior view. x 2.

. 87. ye Posterior view. x 2.
ig. 88. ¥ Mesial sagittal section,
ig. 89. Meles taxus. Anterior surface. x 1
ig. 90. is Superior view. x l.
ig. 91, mi Posterior view. x l.
ig. 92. Mesial sagittal section.

ig. 93. Canis Vinittiarilé ‘Antertot surface. x 1,

ig. 94. i ee a eOrivigw, «5 Ei : rash

ig. 95. Inferior surface. x 1l.-- «+5.
ig. 96. a Mesial sagittal section.

. 97. Canis vulpes, Superior view. x 1.
. 98: A Posterior view. x 1.
» 29, a Mesial sagittal section.
. 100. Cat. Superior view. x 1.

. 101. ., Posterior view. x 1.

ig 102. ,, Mesialsagittal section. x 1.
ig. 103. Ovis aries. Anterior view. x l.
ig. 104, os Posterior view. x 1.

. 105. Goat. Mesial sagittal section. © x 1.

ig. 106. Bos taurus. Mesial sagittal section. x }.

ig. 107. Equus caballus. Anterior superior view. x 3.
ig. 108. 4 Posterior view. x 4.

ig. 109, nt Mesial sagittal section. x 4}.

iri satan act a

oe
24?
[Prate XVII.

“~Ploceulus.

a
/ Kp)-Poreflocosion

= Fic. 53- RRS we:

Professor O. CHARNOCK BRADLEY on the Development and
Homology of the Mammalian Cerebellar Fissures.

Fic. 61.

Gg Ue

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Gk eee

--- Parafleeculus

Professor O. CHARNoCK BRADLEY on the Development and
Homology of the Mammalian Cerebellar Fissures.

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[PLATE XX,

Professor O. CHARNOCK BRADLEY on the Development and
Homology of the Mammalian Cerebellar Fissures.

NS i i i
ales

HAY
FA

{PLATE XXI.

seseen eye Parafleccudus

™Floceulus

: ee Parafloceulus.

Fic. 88. a Fic. 89. @ 1

“saw Paraflocoulus

Professor O. CHARNOCK BRADLEY on the Development and
Homology of the Mammalian Cerebellar Fissures.

“5. Parafloceulvs.

[PLATE XXII.

Parafloc oulus.

ara %. Parafloceulus
‘ *Ploceulus.

Professor O. CHARNOCK BRADLEY on the Development and
Homology of the Mammalian Cerebellar Fissures.

Fe,

Journ. of Anat. and Physiology, Jan. 1903.] [Prats XXIII.

rd
<i. ‘ ---Parafloceul vs

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7

Fic. tor. ~

~------Peraflocoulos.

“~~ Floceulus.

Fic. 104.

Fic. 107.

Professor O. CHARNOCK BRADLEY on the Development and
Homology of the Mammalian Cerebellar Fissures.

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6

OBSERVATIONS ON THE RELATIONS OF THE DEEPER

PARTS OF THE BRAIN TO THE SURFACE. By

_ Jounson Symineton, M.D., Professor of Anatomy, een ¢
College, Belfast. (Puates XXIV. ’.-XXIX,)

Wane the literature dealing with the position of the cerebral
fissures and convolutions in relation to the external surface of
the skull and the scalp is very extensive, much less attention
has been devoted to the study of the superficial relations of the
deeper parts of the brain. This is mainly due to the fact that
the cerebral cortex is now recognised as being within the terri-
tory of ordinary surgical operative work, while the deeper parts
are in the main a hinterland still unexplored by the surgeon’s
knife. A study of the surface relations of the more deeply
placed structures, however, is not only of anatomical interest,
: but may prove of practical importance in determining the
structures involved in deep wounds of the brain, such as gun-
| shot injuries, etc.
_ A considerable number of drawings have. been. published of
] sections through the entire head, but they are usually limited
___toone or two sections through the same head, and thus only
___ indicate the position of a limited number of the deeper structures,
; and these in only a small part of their extent. The extensive
series of photographs of the brain cut in situ which are to be
found in Macewen’s Atlas of Head Sections forms a striking
exception to this statement; but even in this work the absence
of figures giving surface views of the various heads examined,
marked so as to show the planes of the sections in relation to
the surface and the position of the structures between the
various sections, diminishes considerably its practical value.
- The important work of Professor Alec Frazer’ gives more
information on this subject than any other with which I
am acquainted, but a number of the deeper structures are in-
distinctly represented. Both Macewen’s and Frazer’s investi-

1 4A Guide to Operations on the Brain, London, 1890,

242 PROFESSOR JOHNSON SYMINGTON.

gations suffer from the fact that they were undertaken before
the introduction of formol as a fixing and hardening agent.

In this paper I propose to ane the results of a study of the
by a plan I demonstrated and described some years ago.) “Tis
intended to serve as an illustration of this method, as well as
form a contribution to our knowledge of the surface relations of
the deeper parts of the brain. ae Ne

In the last number of this Journal I referred to the specimen
about to be described in a paper entitled “Are the cranial ‘con-
tents displaced and the brain damaged by freezing the entire
head?” and I gave a photograph (see pl. xi) of a median
section of part of the brain. I trust that the present communi-
cation will contain additional proof in support of my contention
that the freezing process does not necessarily distort or displace
the brain in the cranial cavity. i

The results obtained from the study of this head are given in
the illustrations accompanying this paper, and i in the following
description of each plate.

«i

Puate XXIV.

This is from a photograph of the right side of the head of a female
54 years old. The circumference of the cranium, measured at the
level of the glabella and the occipital point, was 20 inches. Its
length from nasion to occipital point was 74 inches, and the biparietal
diameter was 52 inches, giving a breadth index of 79, so that it
comes very nearly within the brachycephalic group. The: height,
from basion to bregma, was 54 inches, giving a height index of 72. -

The photograph was taken after the head had been frozen and cut
into six slabs. These were replaced in their proper order, with sheets
of cardboard between them to represent the thickness of the tissue
removed by the saw. Care was taken to obtain a correct profile
view ; and to secure an orthogonal projection of the peripheral parts,
the head was placed between 5 and 6 feet from the lens. The
photograph obtained was enlarged to life size.

Tue Sxuti.—The soft parts were cut in the median plane down
to the bone, and removed on the right side from the five upper slabs
so as to expose the surface of the skull. Another photograph was
then taken in the same position as the skin view, and. from a full-
size enlargement of this a tracing was taken, so'that the position of
the cranial sutures could be outlined upon the first photograph. . In’

1 Proceedings of the Royal Academy of Medicine in Ireland, vol. xvi. p. 407.

RELATIONS OF DEEPER PARTS OF BRAIN TO THE SURFACE. 243

this plate the articulations of the parietal bone in front, behind, and

below are shown. Behind the upper extremity of the great wing of
the sphenoid (G.W.S.) there is an epipteric bone. The median cut
surfaces of the vaulted part of the skull from the glabella to the
posterior margin of the foramen magnum, of the basi-occipital and
basi-sphenoid, and of the atlas and axis, have been projected on to the
side of the head. The external occipital protuberance is indistinctly
marked, but from the muscular attachments its position is indicated
by a x on the lower part of slab 4. The position of the median
boundaries of the nasal part of the pharynx and the soft palate, as
well as the pharyngeal orifice of the left Eustachian tube, are outlined
on the side of the face.

Tue Brary.—In this plate an outline is given of the structures
visible on the left half of the median section of the brain. It was
constructed as follows :—Upon the upper surfaces of each slab, from
the second downwards, lines were drawn outwards at right angles to
the median plane on to the surface, so as to mark the position on the
lateral aspect of the head of the median portions of the brain. Each
slab was afterwards divided into right and left halves, and a tracing
of the structures exposed in the left half of each slab was transferred
to the corresponding slab in the right profile photograph.

The antero-posterior arch of the corpus callosum is very well

' marked, and also the vertical descent of its splenial end. A _hori-

zontal line uniting points opposite the anterior and posterior extremi-
ties of the corpus callosum is barely 2} inches in length, and the
highest part of the corpus callosum is 1 inch above a line uniting the
lower ends of the genu and the splenium. The whole of the median
portion of the corpus callosum is covered by that portion of the
parietal bone which assists in the formation of the floor of the
temporal fossa, and its highest portion is about half an inch below
the top of the temporal ridge. The genu does not reach quite as
far as the coronal suture, and the splenium is about opposite a
vertical line prolonged upwards from the posterior border of the

_mastoid process. The antero-posterior extent of the corpus callosum

in this specimen is rather less than the average for an adult brain
hardened im situ, where it is generally 3 inches. In an adult male I
found the genn of the corpus callosum to reach nearly a quarter of an
inch in front of the coronal suture, and also to be a little lower than
in this specimen. On an average, we may consider that the genu of
the corpus callosum extends to the level of the lower part of the
coronal suture. Frazer, in his Guide to Operations on the Head, has
two plates, viz., xi. and xxiv., with composite photographs of the
head of a female 38 years old, from which it would appear
that the genu not only reached in front of the coronal suture, but
also downwards so as to be overlapped by the upper extremity of the

' great wing of the sphenoid. In this case, however, the sutures in the

region of the pterion are indistinctly marked, and the great wing
ae to be prolonged upwards and backwards farther than usual.

e portion of the 3rd ventricle above the suleus of Monro lies
above a line uniting the apex of the rostrum and the extremity of the

244 PROFESSOR JOHNSON SYMINGTON.

splenium of the corpus callosum, and is covered by the parietal bone.
The lower or infundibular portion of this ventricle (3’), on the other
hand, is under the squamous portion of the temporal bone. Its long
axis is directed downwards and forwards, and is fully an inch in
length.

The long axis of the medulla and pons is practically vertical. The
junction of these two parts of the brain is opposite the roof of the
external auditory meatus, and about the same level as the vault of.
the nasal part of the pharynx. A horizontal line 1 inch above the
top of the external auditory meatus will mark the level of the upper
limit of the pons Varolii, and another half inch higher the top of the
pons Tarini uniting the two crura cerebri.

The median lobe of the cerebellum is covered by the parietal,
temporal and occipital bones. Its upper extremity, which is a little
behind and at the level of the lowest part of the splenium of the
corpus callosum, represents the highest part of the whole cerebellum.
Its lower end, however, does not reach so low as the lateral lobe
(L.L.), for the inner surface of the amygdalus extends into the
foramen magnum as far down as a line uniting the lowest parts of
the anterior and posterior boundaries of this aperture. The height
of the median lobe of the cerebellum is 2 inches, and a line directed
downwards and forwards from the top of the superior vermis to the
lower end of the amygdalus measures 2? inches.

The principal fissures on the mesial aspect of the left cerebral
hemisphere are indicated by dotted lines. The fissure of Rolando
(F.R.) turns round the superior mesial border 13 inches behind the
bregma, and is prolonged downwards and backwards for a distance
of little more than half an inch. The parieto-occipital fissure (P.O.F.)
cuts the mesial border at the same horizontal level as the apex of the
lambdoidal suture. The part of the calcarine fissure (C.F.) behind
the union of this fissure with the parieto-occipital is just above the
border separating the mesial from the tentorial surface of the
occipital lobe. It will be seen that, viewed from the lateral aspect,
nearly the whole of the cuneate lobule is covered by the parietal
bone.

PuatE XXYV.

This plate shows the position of the fissures and convolutions on
the lateral aspect of the right cerebral hemisphere to the cranial bones
and sutures, and also that of the right lateral, the third and the fourth
ventricles in relation to both the cranium and the convolutions.

Tt will be seen from the view of the skull that the sections of this
head were not made quite parallel to the ear-orbital line, 7.e. a line
uniting the highest part of the external auditory meatus with the
lowest part of the margin of the orbit. A skull so placed as to have
this line horizontal is generally regarded as being in a horizontal
position, and consequently the plane of the sections through this
head are directed from the front backwards and a little downwards,
so as to make an angle open to the front of about 10 degrees with the

RELATIONS OF DEEPER PARTS OF BRAIN TO THE SURFACE. 245

horizontal plane. This does not, of course, affect the accuracy of the
orthogonal projections of the deeper structures on to the side of the
head.

Professor A. Froriep! has divided the variations in the position of
the cerebral hemispheres in relation to the skull into two main
groups, which he names frontopetal and occipitopetal. In the former,
the brain lies farther forwards; in the latter, it may be supposed to
have been pressed backwards, and the occipital pole depressed. In
order to illustrate the differences between these two groups, a line is
drawn from the lowest part of the margin of the orbit backwards
through the highest part of the external auditory meatus. From
this horizontal base line another is drawn vertically upwards from
the centre of the external auditory meatus. In the frontopetal type
the vertical line crosses the fissure of Rolando further forwards, and
the occipital lobe is higher in relation to the horizontal line than in
the occipitopetal type. This brain belongs to the frontopetal type.
Thus the general direction of the lower border of the temporo-
occipital part of the hemisphere is backwards and upwards when
compared with the ear-orbital line, so that the lowest part of the
occipital lobe is nearly 2 cm. above this line.

The Sylvian point, the spot where the Sylvian fissure is seen on —
the lateral aspect of the brain dividing into its anterior and posterior
branches, is a trifle higher up and farther back in relation to the
pterion than usual; still the position of the Sylvian fissure may be
regarded as well within the range of normal variations.

The fissure of Rolando measured in a straight line on the surface
of the brain from the superior mesial border of the hemisphere to its
termination above the Sylvian fissure is 34 inches long. In a profile
View it is 2} inches. This difference is, of course, due to its passing
outwards as well as forwards and downwards; thus, at the upper
surface of slab 2, the fissure is 2 inches from the median plane.

The literature dealing with the relations of the lateral ventricles to
the surface of the brain and skull is scanty, and refers chiefly to the
question of the best surgical route to its cavity.

In plate xxi, Frazer? has an excellent view of the lateral ventricles
exposed from the right side, with the central lobe and the caudate
nucleus still in situ. In consequence of these structures not having
been removed, only the outer border of the body of the lateral
ventricle is visible, but the three horns are distinctly seen, all of
them being well developed, more especially the posterior one.
Professor Thane * has a diagram of an outline of the cavity in relation
to the side view of the skull and of the Rolandic and Sylvian fissures,
but otherwise our anatomical text-books do not attempt to indicate
its position with reference to the surface. Mr E. A. Spitzka* recently

Aa Lagebexichungen zwischen Grosshirn und Schideldach, Leipzig, 1897.
Op. cit., p. 241.
. ¥ Quain’s Anatomy, Appendix, 10th edition, 1896, fg. 5.
*A preliminary communication, with projection drawings illustrating the
ot of the paraceeles (lateral ventricles) in their relation to the surface of
the cerebrum and the cranium, New York Med. Jowrn., 2nd Feb, 1901.

246 PROFESSOR JOHNSON SYMINGTON.

published a short paper giving the results of his examination of two
adult heads. He gives a full-size outline (fig. 1) of a side view of
the skull of one of these heads, with the convolutions and lateral
ventricle, and similar outlines (figs. 4 and 5) of both sides of the
other head he investigated. The brains were hardened in situ, removed
from the cranial cavity and divided in a coronal direction into
sections a quarter of an inch thick. No explanation is given as to how
the relations between the skull and the brain were determined, and
from an examination of Spitzka’s drawings I must confess that their
accuracy in this respect is very doubtful. Thus, in fig. 1, a base line
is drawn from the external angular process of the frontal straight to
the inion. This line is figured as passing just below the external
auditory meatus, whereas, in a normal skull, it would go above the
auditory meatus, as it does when marked upon his figs. 4 and 5,
Again, in fig. 1, the lower limit of the temporal lobe of the brain
crosses the external auditory meatus just below its upper border, and
the descending horn is depicted as only a quarter of an inch above the
level of the upper border of the meatus. His drawing thus ignores
the existence of a thick bony roof to the meatus, or an attic to the
tympanic cavity.

In this Journal Dr J. O. Wakelin Barratt! gives a drawing (fig. 2)
of a profile view of the left side of the brain, with the relations of the
lateral and third ventricles to the convolutions. Barratt’s figure may
be compared with that of this plate, but it must be noticed that the
‘horizontal’ line he marks on the brain would be by no means
parallel with the ear-orbital line of the skull. The frontal end of the
brain is tilted downwards so that it reaches fully as low as the
occipital lobe, and the posterior horn of the lateral ventricle is about
as high as the body of the lateral ventricle.

In my specimen the cavities of both lateral ventricles are rather
small, especially in their cornual portions. On the right side the
highest part of the body of the ventricle, which is formed by its outer
border, is 3 inches above the roof of the external auditory meatus,
half an inch below the highest part of the temporal ridge, and 2 inches
from the top of the head. The anterior cornu formed a mere slit in
front of the head of the caudate nucleus; but had it been dilated to a
degree frequently met with in normal brains, it would have reached
as far forwards as the coronal suture.

If pl. xxi. of Frazer's work,? showing a profile view of the left
lateral ventricle, be compared with his pl. ii. containing a view from
the same aspect of the surface of the skull, the anterior horn will be
found to reach as far as this suture. Thane® figures this horn as
projecting fully half an inch in front of this suture, but a position so
far forwards is probably unusual, unless it be abnormally distended.
The posterior horn is so variable in its development that it is difficult
to strike an average. In my specimen it is certainly narrower and

1 **The form and form-relations of the human cerebral ventricular cavity,”
Jour. Anat. and Phys., vol. xxxvi., Jan. 1902.
2 Op. cit., p. 241, 3 Op. cit., p. 245.

i

—— enelemt

RELATIONS OF DEEPER PARTS OF BRAIN TO THE SURFACE. 247

shorter than usual. The cavity of the descending horn was little
more than a slit, and in a diagram indicating its average size my
outline would require to be slightly thickened and lengthened. The
most important part of the ventricle from a surgical point of view is
where the body turns downwards and outwards, to end in the de-
seending and posterior horns. Its cavity is not liable to be reduced
to a mere slit, as is the case with nearly all the other parts of the
lateral ventricle, and, with the exception of the upper part of the
descending horn, it is nearer the lateral surface of the brain than any
other part of the ventricle ; hence it is the portion selected for tapping
or injecting the ventricle. This region is marked in this plate by a
circular spot, and it is shown in section in Pls. XXVI. and XXVII.
In my specimen it is opposite the posterior part of the superior temporal
convolution, about an inch behind and 2 inches above the external
auditory meatus. Dr Keen’s! point for reaching the ventricle is
1} inches above and behind the external auditory meatus.

The surface relations of the 3rd and 4th ventricles are represented
in Pl. XXIV. as well as in this plate. No attempt has been made to
give the position of the lateral extension of the 4th ventricle.

Professor Gustaf Retzius,? in his beautiful illustrations of casts of
the ventricles, gives a side view (fig. 1) of the lateral ventricle, with
the depression for the caudate nucleus shaded. The head of this
nucleus lies external to the anterior horn and to the anterior part of
the body of the lateral ventricle, and its tail follows the curve of the
upper border of the descending horn. From this plate, therefore, the
position of the caudate nucleus can be determined. It will be
noticed that the outline of the anterior horn of the lateral ventricle
shows in the lower part of its anterior border a concavity directed
forwards. Instead of this concavity the head of the caudate nucleus
bia show a convexity.

Pirate XXVLI.

| This is from a tracing of the upper surface of slab 3. The plane
of this section is seen in profile in Pls, XXIV., XXV. and XXIX.,
and, as already explained, it is not quite horizontal, being a little
higher behind than in front. The section is so typical of one com-
monly used to illustrate the form and relations of the nucleus caudatus
(N.C.), optic thalamus (O.T.), internal capsule (Int. Cap.), nucleus
lenticularis (N.L.), external capsule, claustrum, and island of Reil,
as to render any detailed description unnecessary. The island of
Reil is cut a little below its superior limiting sulcus, and opposite its
greatest antero-posterior extent. On the right side the convolutions
of the fronto-parietal operculum lying above the island of Reil (I. of R.)
and the superior temporal convolutions (S,T., S.T.), which were

1 Buck’s Reference Handbook of the Medical Sciences, vol. viii., 1889.
2 “Die Gestalt der Hirnventrical des Menschen, nach ’ Metallausgiissen
dargestellt,” Biologische Untersuehungen, Bd. ix., 1900.

248 PROFESSOR JOHNSON SYMINGTON.

separated from the rest of the brain in making this section; have
been removed to show the latter structures. On the left side the
opercula of the island of Reil were cut a little lower, and only two
pieces of the fronto-parietal operculum (F.P.O.) projected below the
plane of this section. The dotted lines starting from the posterior
part of the body of the lateral ventricle indicate the course of the
posterior and descending horns in a view from above. The descending
horn usually turns more inwards at its lower and anterior extremity,
but the cavity which passes towards the median plane is aaly” a
narrow cleft.

Pratt XXVIII. i

We have here a photograph of two sections of the brain. The one
on the left side is the same as that’ shown on the left half of the
section in Pl. XXVI., but on the right half the following dissection
of slab 3 was made before the photograph was taken. The brain was
divided vertically just to the right of the median plane, and the right
half removed and cut horizontally 10 mm. below its upper surface.
On this side also the lateral wall-of the skull was removed from
opposite the posterior part of the roof of the orbit backwards to the
median plane. The lower part of the brain belonging to the right
side was then replaced in position, and the two sections photographed
together. This dissection was made more than a year after the head
had been frozen and divided with a saw. It will be noticed that the

surface is smoother, and the differentiation of the white and grey

matter is better marked on the right side. These differences are due
to the fact that the cut surface on the right side had not been
subjected to much handling or exposure to the light, and also to its
having been cut with a knife instead of a saw. The slight retraction
of the anterior part of the left cerebrum from the skull is due to
the frequent manipulation of the brain in removing and replacing
it, and is not shown in the photographs taken before the brain was
disturbed,

On the right section of the brain the anterior limb of the internal
capsule is represented by a thin layer of fibres, so that the nucleus

caudatus and the nucleus lenticularis nearly meet. Two segments of

the globus pallidus (G.P.) are exposed internal to the putamen, while
at the level of the left section only a small piece of one of these

bodies is visible. The posterior limb of the internal capsule is still

well marked, Its retro-lenticular portion (R.L.) is said to contain
auditory fibres going to the superior temporal convolution (8.T.), and
behind these visual fibres (O.R.), passing backwards to the occipital

lobe. The splenium of the corpus callosum (C.) is divided close’
to its extremity, so that the fibres of the forceps major (F.M.)
which come from the splenium must have curved downwards as well’

as backwards. The letters P.O.F. are placed behind the parieto-
occipital fissure, which is exposed close to its union with the osaarme
fissure. 7

RELATIONS OF DEEPER PARTS OF BRAIN TO THE SURFACE. 249

Watdites a:

tae Prare XXVIII.
r

_ The upper surface of slab 4 is shown here. The cut separating
this from slab 3 traversed the upper part of the nasal cavities and
the ethmoidal air-cells (E.C.), and in the orbits exposed the optic
nerves from the eyeball backwards and inwards to the optic foramina.
The parts of the brain divided were the upper end of the pons
Varolii, valve of Vieusseus, and 4th ventricle, the cerebellum, and the
temporal and occipital lobes of the brain. The upper edge of the
dorsum selle was removed by the saw, and the 3rd nerves cut behind
it, om the internal carotid arteries opened in front and to its outer
si ;

In the temporal lobes are seen the cavities of the descending horns
(D.H.).of the lateral ventricles. They reach about as far forwards
as the front of the pons, but are 14 inches behind the anterior
extremities of the temporal lobes.
fire.

Puate XXIX.

In this plate we have made an attempt to represent the position in
relation to the side of the head of the pyramidal motor fibres from
the Rolandic area, and also that of the visual tracts, together with
certain parts of the brain related to these fibres. This diagram has
been constructed by similar methods to those of Pls. XXIV. and XXV.
already described. The outline of the skin (1) and the skull (2) are
indicated by black lines, while the periphery of the cerebral hemi-
spheres (3) and the Sylvian and Rolandic fissures are represented by
interrupted lines. The outline of the cuneate lobe is taken from the
left hemisphere of the brain.

Above the pons Varolii (Po.) and the superior cerebellar peduncles
(S.P.) is seen the external aspect of the mid-brain, with its crus
cerebri in front and the corpora quadrigemina behind. Above this is
a dotted area for the optic thalamus, while the letters A and P are
placed near the front and back of the internal capsule. The antero-
posterior extent of the posterior limb of this capsule will, of course,
correspond with the optic thalamus, external to which it lies. The
mid-brain is in the lower half of slab 3, under cover of the upper part
of the squamous portion of the temporal.

Pyramipat Fisres.—The letters L, A, T placed in front of the
fissure of Rolando indicate generally the position of the motor centres
for the leg, arm, tongue and face. E, put farther forwards, is the
centre for the movements of the eye and the head. The axis-cylinder
processes from the motor cells in these regions will descend in the
corona radiata and then enter the internal capsule. This capsule is
shown in section in Pls. XX VI. and XXVII. The pyramidal fibres are
represented as traversing the knee and the anterior part of the posterior
limb of the capsule. In consequence of the oblique direction of the
fissure of Rolando, the leg cortical area is in a plane posterior to that

250 RELATIONS OF DEEPER PARTS OF BRAIN TO THE SURFACE,

for the arm, and this again is behind the face and tongue centres.
The pyramidal fibres are believed to occupy the same relative position
in the internal capsule. Some of the pyramidal fibres from E may end
in the mid-brain in relation to the origin of the 3rd nerve, those from
T in the medulla and pons, while of course the arm and leg sees go
into the spinal cord.

When this tract is projected on to the side of the head it will be
noticed that the course of its fibres is nearly vertical, although they
necessarily converge as they descend. A line from the external
auditory meatus to the bregma and another from the same point to
the vertex about 2 inches behind the bregma would include the’ area
occupied by these pyramidal fibres.

VisuaL Freres.—It was shown in Pl. X XVI. that the cut which
separated the third and fourth slabs divided the eyeball and exposed
the right optic nerve as far back as the optic foramen. From this
opening the optic nerve passes upwards and backwards to the optic

commissure, and the optic tract goes in the same direction, except that

it inclines also outwards external to the interpeduncular space and
the crus cerebri, to end in the lower visual centres, viz., the superior
quadrigeminal bodies, the lower and posterior part of the optic
thalamus and the corpora geniculata, From these lower centres fibres
are represented passing backwards as the optic radiation to the cuneate
lobule and the gyrus lingualis. The upper and lower limits of this
optic radiation have not been precisely defined, but this tract is very

distinctly seen in the section of the right side of the brain in Pl.’

XXVII. If other fibres pass from these parts of the cortex to an
association centre in or near the angular gyrus, they must go outwards
and upwards,

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Journ. OF ANaT. AND PuysioLocy, Afril, 1903 [PLaTE XXIV.

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PROFESSOR SyMINGTON.

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PROFESSOR SYMINGTON.

JOURN. OF ANAT. AND PuysloLocy, April, 1903 [PLate XXVII.

PROFESSOR SyMINGTON

[PLate XXVIII.

Journ. oF Anat. anp Puysio.ocy, April, 1903.

PROFESSOR SYMINGTON,

JouRN. oF ANAT. AND PuysioLocy, Afril, 1903. [Prate XXIX.

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Plate VI.

PROFESSOR SYMINGTON.

Pi Rtas ae

——

AN EXAMPLE OF A PECULIAR MALFORMATION OF
THE TRICUSPID VALVE OF THE HEART. By
T. Warprop GrirrirH, M.D., M.R.C.P., Professor of
Anatomy at the Yorkshire College ; Senior Assistant
Physician to the General Infirmary, Leeds. (PLaTE XXX.)

THIS specimen came under my notice when I was making a
post-mortem examination in the case of a little girl of the age
of 5, who had died of cancrum oris. Before beginning the
examination, I noticed that the finger-ends were clubbed to a
slight but to an unmistakable extent, and this led me to express
to the students who were present my suspicion that we should
find either some congenital malformation of the heart, or some
pleural or pulmonary disease of long standing. So far as could
be ascertained, no cyanosis had been observed during life.

The heart was preserved in dilute spirit, and was not ex-
amined in detail for some months. The organ weighed 1260
grs. The circumference of the aorta was 1% inches, that of the
pulmonary artery 13, so that not only was there a reversal of
the normal relationship as to circumference between these two
vessels, but the difference in this case amounted to no less than
half an inch.

_ The foramen ovale was widely patent, its valve small, reach-

ing only about half-way across the aperture, and in part

net-like. The continuity of the Eustachian valve with the
Thebesian was very well marked, and was of such a kind that
the coronary sinus opened into the same part of the auricle as
the inferior vena cava. I may remark in passing that this
peculiarity of the coronary sinus opening into the sinus venosus
rather than into the auricle proper was also noticed by me ina
specimen, shown at the meeting of the Anatomical Society
held in 1896, of congenital cardiac malformation, with im-
perfection of the interauricular septum, an absence almost
complete of-the ventricular septum, and non-differentiation of
the two auriculo-ventricular openings from one another. In
the discussion which followed, Prof. Thane made the interesting

252 PROFESSOR T. WARDROP GRIFFITH.

observation that this manner of opening of the coronary sinus
might be regarded as a persistence of the primitive arrange-
ment, the coronary sinus opening, of course, in the first
instance, into the sinus venosus, of which indeed it forms the
left horn, and that the condition normally found in the adult
must be due to some rearrangement, at present not fully
understood.

Both auricles were capacious, possibly mato so; the left
ventricle was disproportionately large and thick- walled as
compared with the right.

Both flaps of the mitral valve showed an extreme degree of
development of the thin net-like portion at the free margin, so
that in the case of the anterior segment the measurement from
the attached to the extreme free margin was two inches. The
posterior segment was composed of at least two subsidiary
flaps. '

The aortic flaps were normal, aaa much more substantial
than the pulmonary.

The right ventricle, as already remarked, was smaller Ric
the left, and entered into the formation of the apex less than
normally. Externally, it was noticed that just below the
auriculo-ventricular furrow the part of the ventricular wall
forming the margo acutus and the adjoining part of the anterior,
aud to a greater extent of the posterior, surface of the heart
was very thin, and almost devoid of muscular tissue.

- There was a very profound malformation of the ‘ticumpid
valve. The septal flap was quite isolated from the others,
looking rather like an inverted semilunar segment, without
distinct chorde tendinez, but having its usual relationship to
the pars membranacea septi. The left or great flap was less
fringed at its margins than normally, its upper commissure was
fixed by confluent and rudimentary chorde to the septum, ©
quarter of an inch from the septal flap, while, when traced to
the right, the ventricular aspect of this flap was found to be
obscured by great coluinns of muscular tissue passing from the
upper part of the ventricle downwards to the lower part of the
anterior wall, and closely adherent to the valve. Between
these columns, in some parts, the fibrous tissue of the valve
was visible, and at two places small dome-like projections. of

OO es

— oe

bial Nis anal ————

PECULIAR MALFORMATION OF THE TRICUSPID VALVE. 253

this fibrous tissue were seen, with apertures at their apices,
whose margins were provided with chorde tendinee attached
at the other end to the above noted muscular bands passing to
the ventricular wall. It would appear from a careful replace-
ment of the cardiac walls where these had been cut that the
free margin of the anterior flap had been directed upwards and
forwards to the pulmonary artery, and the whole of this free
margin would correspond in a normal valve to that part of the
flap extending from its apex to its junction with the septal
flap. This margin bounded with the upper part of the septum
and the septal flap of the tricuspid, a narrow strait through
which most of the blood would pass on its way from the
auricle to the ventricle. The rest of the margin of the great
anterior segment was obscured by muscular bands as above
described.

A probe passed from the pulmonary artery, therefore, could
pass in two ways, viz., (1) along to the right into a gradually
narrowing portion of the ventricle, which became blind at the
margo acutus, and into which the two funnel-like apertures
above mentioned opened, or (2) down between the anterior and
septal flaps into another part of the ventricle.

The deformity of the posterior flap may best be understood
by suggesting as a possible explanation of its condition, that it

- had been destroyed at its auriculo-ventricular attachment, and

become adherent along its entire free margin with the
ventricular wall, a condition associated with, complete dis-
appearance of the chord tendinee and musculi papillares,
and also associated with a large deficiency in the upper part of
the flap and a smaller one nearer the septum.

From the right auricle, therefore, the blood might have passed
(1) into the left auricle through the patent foramen ovale,
or (2) through the auriculo-ventricular opening into the second
part of the ventricle referred to above; here the blood would
in the first instance pass in part behind the posterior segment
of the tricuspid valve, and reach the main stream by sweeping
above its upper margin or going through the deficiencies in its
substance, whence it would pass directly to the conus arteriosus
and pulmonary artery by going between the free margin of the
tricuspid valve and the septum, and indirectly by going through

VOL. XXXVII. (N.S. VOL. XVII.) —APRIL 1903. 18

254 PECULIAR MALFORMATION OF THE TRICUSPID VALVE.

the two crater-like orifices described above as opening into the
blind part of the ventricle, whence, of course, it would pass to
the left and upwards to the pulmonary exit.

It is clear, therefore, that there must have been some slight
obstruction to the passage of the blood through the right
ventricle ; and in harmony with this we note that the ielenenaey
artery was much smaller than the aorta.

Jour. of Anat, and Physiology, April 1903.) [PLaTe XXX,

br..

A, in right auricle, points to crista terminalis, Auricular septum and foramen ovale not
shown. B, isolated septal flap of tricuspid valve. C, in second or blind part of
right ventricle, points to the two crater-like orifices in the anterior tricuspid
segment, which is here concealed by fleshy columns.

Pror. Warprop GRIFFITH.

NOTE ON A SECOND EXAMPLE OF DIVISION OF THE
CAVITY OF THE LEFT AURICLE INTO TWO COM-
PARTMENTS BY A FIBROUS BAND. By T. Warprop
GrirFitH, M.D., M.R.C.P., Professor of Anatomy, Yorkshire
College, Leeds; Assistant Physician, General Infirmary,
Leeds. (Puate XXXTI.)

AT the meeting of the Anatomical Society held in February
1896, I showed a heart with a fibro-muscular band passing
across the left auricle, which had the effect of partially dividing
that cavity into two compartments,—an upper, receiving the
pulmonary veins, and a lower, which communicated with the
ventricle and with the auricular appendix. I have recently met
with another specimen presenting so many points of resem-
blance to the former that I think it:should be put on record as
well.

The heart was obtained at the post-mortem examination of a
male patient who died at the age of 48 of chronic Bright's
disease. The organ was much hypertrophied, and there were
slight degenerative changes at the root of the aorta and in the
mitral valve, which, however, appeared to have been competent.

The plate in illustration of this communication is from a
photograph taken by Mr Michael Teale, one of our honorary
demonstrators. F

The left auricle was partially divided into two compartments
by a broad fibrous band, which started from the auricular
septum where it was continuous with the tissue of the valvula
foraminis ovalis, from which it arose by several spurs. This
band passed upwards and forwards below the upper right
pulmonary vein, then along the anterior and left walls of the
auricle, having now a downward direction, and passing just
below and in front of the left pulmonary veins, and finally
becoming narrower, was lost on the posterior wall of the auricle,
about one inch above the auriculo-ventricular furrow. By its
concave margin, which was well defined and smooth, it formed
about three-fifths of the circumference of the aperture of com-
munication between the two compartments of the auricle, the

256 PROFESSOR T. WARDROP GRIFFITH.

remaining two-fifths being formed by the auricular wall at the
posterior part of the septum and the adjacent part of the
posterior wall. The aperture admitted of the passage of two
fingers easily. Where the band was attached to the auricular
wall, it presented several small deficiencies, through which a
crow quill could be passed from the upper or posterior to the
lower or anterior compartment of the auricle; these were
situated towards the anterior and left part, where the band
was thinner than elsewhere. Into the upper compartment of
the auricle there opened the four pulmonary veins, the floor of
the superior right and of both the left being directly continuous:
with the posterior or upper aspect of the band, while the inferior
vein of the right side opened into the auricle some distance
behind the origin of the band from the valve of the foramen
ovale. The lower compartment of the auricle was in communi-
cation with the appendix, and, of course, with the ventricle
through the mitral orifice. The foramen ovale was completely
closed.

In commenting on my former specimen at the meeting of the
Anatomical Society, I suggested as a possible, but as I said a
highly problematical, explanation of the presence of the band,
that there had been a failure in the complete amalgamation of
that part of the auricle which is said to be formed from the
confluent portions of the pulmonary veins and that derived
from the left-hand division of the common auricle of the
embryonic heart. This view did not meet with much accept-
ance at the meeting; and it was indeed advanced by me in a
very tentative manner, and with no very strong conviction of
its accuracy.

At the same meeting Dr Rolleston showed a band in the left
auricle of a boy’s heart, which was round and fibrous and
crossed over the orifice of the mitral valve, but this was
attached to the wall of the auricle below the appendix and
below the level of the fossa ovalis. He also referred to Dr
J. K. Fowler’s specimen (Path. Trans., 1882) of a band #-inch
wide, with its edges vertical, which was attached to the septal
wall, being here continuous with the membrane forming the
fossa ovalis, This band was regarded by Dr Fowler as an over-
growth of the valvula foraminis ovalis, swept by the blood-

a

XXXI.

(PLAT

L

DIVISION OF THE CAVITY OF THE LEFT AURICLE. 257

stream to the outer wall of the auricle, where it had become
adherent.

In writing an account of my specimen, which I did after
perusing the account of Dr Fowler’s case, I came to the con-
clusion that he was correct in regarding the band as a re-
dundancy of the tissue of the valve of the foramen ovale, and
that my specimen was an example of the same thing; but I
expressed my belief that in both cases we had to do with a
mere exaggeration of a state of affairs not usually regarded as
abnormal, viz., the presence of retinacula proceeding from the
margins of the valve of the foramen ovale, which might or might
not be patent.

At the meeting of the Society held at Cambridge in 1899,
Professor Sidney Martin showed a specimen presenting a very
strong resemblance to mine, and advanced the same explanation
which I had, with great hesitation, given in 1896. Dr Rolleston’s
specimen showed a rounded band, and its attachments were
different. I have not had the privilege of examining Dr Fowler’s
specimen, but his description would lead me to think it resembled
my specimen rather than Dr Rolleston’s; between my two
specimens and Dr Sidney Martin’s there is so strong a resem-
blance that I cannot regard the condition as in any way due to
pathological causes, of which, indeed, there is no evidence, but
I think it must depend on some such anomaly of development
as has been suggested by Dr Martin and myself. Perhaps,
when the development of the pulmonary veins and their manner
of junction with the left auricle is more fully understood, the
explanation may become less uncertain.

THE CEREBRUM OF A MICROCEPHALIC IDIOT. By
N. C. Macnamara, F.R.C.S., and R. H. Burns, Anatomical
Assistant in the Museum of the Royal College of Surgeons of
England.

THE following notes have been kindly sent to us by Dr F.
Pritchard Davies.

F. W. B. was admitted into the Kent County Asylum in
December 1886. He remained in that institution until his
death, which took place when he had reached the age of twenty-
two years. He was 4 feet 8} inches in height; his features
are stated to have been “ large and coarse (fig. 1), and devoid of
expression; his arms were better developed than his body,
head, or legs, giving him a simian appearance. His cranial
development was of alow type; the occipital bones had fused
early, and the size of the cerebrum was insignificant.”

The report further states that F. W. B. “ was unable to speak,
but expressed his wants and such ideas as his mind could
formulate by signs and inarticulate noises. He was entirely
devoid of intelligence, but seemed to appreciate the sound of
musical instruments. He had to be constantly under super-
vision, as he was mischievous and dirty in his habits. F. W. B.
was very passionate, and when out of temper became violent,
throwing himself on the ground, uttering loud inarticulate
sounds, and beating his chest and face with his hands until his.
mouth and nose bled.” His eyesight and sense of smell and
hearing were good. When twenty-two years of age he de-
veloped phthisis, and died somewhat suddenly.

From notes taken at the time of the post-mortem examina-
tion of F. W. B.’s body, we learn that “from the glabella to the
occipital protuberance his skull measured 74 inches, and from
the tip of one mastoid process to the other 8} inches. The
circumference of the cranium round the line of the occipital
protuberance and frontal eminences measured 14} inches.”
No other measurements of the skull are recorded. The brain
weighed 124 ounces; “the cerebellum projected ? of an inch

ee ee ee

CEREBRUM OF A MICROCEPHALIC IDIOT. 259

beyond the occipital lobe.” The brain had been preserved in
spirit for some years before it came into our possession. At
the time of making the post-mortem, the saw had cut into the
surface of the cerebrum, and to some extent damaged the
specimen, as shown in fig. 3.

This specimen is now in the Museum of the Royal College of
Surgeons of England (No. D. 683, Physiol. Series). From a

Fie. 1.

photograph taken of its vertex, it will be seen that the cerebral
hemispheres do not by any means cover the cerebellum (fig. 2).
The remarkably small size of this adult human brain, and the
defective development of its frontal opercula, and of its parietal
and occipital lobes, are its most striking features.

In F, W. B.’s cerebrum the stem of the Sylvian fissures in
both hemispheres and their posterior horizontal limbs are alone
present. The posterior ramus of this sulcus on the right side

260 MR N. C. MACNAMARA AND MR R. H, BURNE.

is nearly at a right angle with the long axis of the cerebrum;
on the left side it has an angle of about 65°.

In the left hemisphere the orbital and frontal opereula are
wanting, and the fronto-parietal operculum is imperfectly de-

Fic. 2.—View of the brain of F, W. B. as seeu from above.

veloped, the insula being only partially covered by the temporal
operculum (fig. 3), In the right hemisphere this condition of
the opercula was marked, but in order to expose the whole of
the island of Reil on this side, portions of the frontal and
temporal lobes have been removed (fig. 4). It will be seen that

CEREBRUM OF A MICROCEPHALIC IDIOT. 261

the insula in F. W. B.’s brain consists of a small smooth nodule ;
it has no gyri or sulci on its surface, unless the depression
on its lower and anterior part may be taken to be a rudi-
mentary longitudinal fissure. The fronto-orbital sulcus is well
defined; commencing on the orbital surface of the frontal lobe
and bending round the lateral margin of) the hemisphere, it
ascends for a short distance on its outer surface. This sulcus,
as Professor D. J. Cunningham has demonstrated, forms the
anterior limiting sulcus of the island of Reil in the anthropoid

Fic. 3.—Left profile view of the brain of F. W. B.

apes; it also clearly bears this relation to the insula in the
case of F. W. B.’s cerebrum (fig. 4).

If we compare the conformation of the surface and the size
of the island of Reil in F. W. B.’s cerebrum with that of a full
grown chimpanzee or of an adult human being (fig. 5 and fig. 6),
it will be seen how extremely ill-developed the insula is in the
case of this idiot.

Professor D. J. Cunningham has described and given excellent
drawings of two microcephalic brains, which in the anatomical
relation of the parts forming the Sylvian and insular region are
almost identical with that of F. W. B.’s cerebrum,’ The same

1 The Scient. Trans, of the Royal Dublin Society, vol. v. (series ii.) p. 287, 1895.

262 MR N. C. MACNAMARA AND MR R. H. BURNE.

remark applies to the fissure of Rolando, which on the right
side of F. W. B.’s brain does not reach the supero-mesial border
of the hemisphere; on the left side it bifureates before reaching
this border. This suleus is shallow and has smooth walls; it
bifurcates at its lower extremity in both hemispheres.

On the right and left side of this brain the superior and inferior
precentral sulci form continuous fissures; from their lower part
sulci pass into the gyrus frontalis medius, The superior frontal
sulci on both sides are broken up into shallow furrows, and it is

50 Te

Fig. 4.—Right profile view of the brain of F. W. B. The fronto-parietal and the
temporal opercula have been removed. 4a, island of Reil; 0, fronto-orbital
sulcus ; ¢, 3rd frontal gyrus.

difficult to define the middle from the superior gyrus, The
lower frontal gyri, as already stated, are defective as regards
their opercula, and are altogether ape-like in their conformation.

It is, however, in that part of the cerebrum which lies
posterior to the central sulcus that the most marked anomalies
are noticeable in F. W. B.’s cerebrum. The calloso-marginal
sulci cut into the superior borders of the hemisphere, posterior

CEREBRUM OF A MICROCEPHALIC IDIOT. 263

to the upper end of the central fissure. The intraparietal sulci
in both hemispheres are of an ape-like character, and form
continuous fissures which pass diagonally across the parietal
lobes.

The parieto-occipital sulci on the lateral surface of the hemi-
spheres, especially on the left side, pass into fissures which
correspond to that of the ‘affenspalte’ of the ape’s cerebrum,

Fic. 5.—Brain of chimpanzee. The opercula have been removed to expose the
insula,

but there is no occipital operculum, although these sulci are
crossed by one if not two deep annectant gyri. On the mesial
surface of F. W. B.’s cerebrum we find that the occipito-parietal
sulci are short, and in both hemispheres are separated from the
ealcarine fissures by a superficial gyrus cunei. The calcarine
suleus forms a deep fissure, extending from the hippocampal
sulcus to the posterior margin of the abortive occipital lobe; it
is throughout its length on the tentorial surface of the cerebrum.
External to the calcarine, the collateral sulcus extends forward
to near the anterior border of the temporal lobe. The calloso-

264 MR N. C. MACNAMARA AND MR R. H. BURNE.

marginal sulcus on the left side forms a well marked continuous
fissure ; on the right side, the posterior and median portion of
this sulcus are united, the anterior part forming a separate
fissure.

The temporal lobes project but slightly beyond the inferior
terminal portion of the great limbic lobe. In both lobes the
first and second sulci are clearly defined, but the third fissure
can hardly be said to exist.

Fic. 6.—Normal human brain. The opercula have been removed to expose
the insula.

It is unnecessary for us to enter on a more detailed account
of this brain, for, as we have already remarked, its anatomical
characters closely resemble those so ably and fully described by
Professor Cunningham. But so far as the structure of F. W. B.’s
cerebrum is concerned, it is clear that it differs less from the
brain of anthropoid apes than it does from the cerebrum of a
normal adult human being. We may go beyond this, and state
that the brain of this microcephalic idiot in its anatomical
characters is more closely allied to that of an adult male chim-

CEREBRUM OF A MICROCEPHALIC IDIOT. 265

panzee than it is to a human cerebrum at any stage of its
development.

Although more than one brain centre is concerned in the
faculty of speech, it is certain that the region of the cerebrum,
which is formed by the opercula of the third frontal gyrus of
the left hemisphere, has a direct influence over man’s character-
istic power of intelligent language. In the case of F. W. B.
these opercula can hardly be said to exist, and the insula is
only present in a rudimentary form. This point is more forcibly
demonstrated by reference to the photographs (figs. 4, 5 and
6) than by any written description we can give, But from
other microcephalic brains in our possession, this almost total
want of development of the insula is by no means so constant
a character of these cerebral hemispheres as is that of their
defective frontal opercula.

It is useless to dilate on the interest which the histories of
the cases above referred to possess in connection with the
anatomical characters presented by these brains, It is much to
be desired that series of such histories and brains should be
brought together in our large museums, so that they might be
carefully studied and compared with one another. They should
comprise “brains in which no pathological taint can be dis-
covered, and which present certain common morphological
features, and a certain more or less easily distinguished uni-
formity of type.” ?

1 Sci. Trans. Roy. Dub. Soc., vol. v., 1895, p. 289.

A DESCRIPTION OF SOME ANOMALIES IN NERVES
ARISING FROM THE LUMBAR PLEXUS OF A
FETUS, AND OF THE BILAMINAR MUSCULUS
PECTINEUS FOUND IN THE SAME FCTUS;
WITH A STUDY OF THE VARIATIONS AND
RELATION TO NERVE SUPPLY IN MAN AND
SOME OTHER MAMMAIS. By Epwarp B. Jamigson,
M.B., Ch.B., University of Edinburgh.

OnE of the chief points of interest in connection with the
anomalies given in the following description is that they have
all been found in one subject. Similar or identical irregularities,
occurring usually singly, have been described before; but it is
uncommon to find in one subject an aggregation of anomalies
which do not stand related to one another. In extreme forms
of lumbar plexus, of either high or low type, one expects to find
correlated variations in the origin of nerves; and when a number
of nerves have peculiarities in origin, it is usually due
to the form of the plexus. In the case hereinafter
described, however, the plexus was of ordinary type, and the
two principal nerves—the Anterior Crural and the Obturator—
were formed in the usual manner. The peculiarities affected
certain of the smaller nerves—the Ilio-hypogastric, and the
External and Middle cutaneous nerves of the thigh ; and besides,
there were found nerves which do not commonly exist—two
Accessory Obturator nerves, and one which might be called the
Accessory Anterior Crural nerve. Moreover, these irregularities
were not symmetrical; the only feature in those irregularities
which the plexuses of the two sides had in common was the
presence of an Accessory Obturator nerve on each side.

The bilaminar Pectineus in this case is of interest, firstly, in
that it was present along with an Accessory Obturator nerve,
and yet received no branch from it; and secondly, in that it

1 J have to thank Dr Waterston for kindly placing some of his material
at my disposal for the purposes of this investigation.

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF FETUS. 267

was found in a fcetus (female, 5} months). The study of most
abnormalities in a foetus is of value as a means of throwing
light on the problems of adult structure, and many such
problems are elucidated only by the study of the arrangements
of fcetal structure, as that is still undergoing development; and
the advantages increase when, in a foetus, a condition is found
akin to the occasional anomalous conditions found in the adult.
In the case of muscles, it may not only be as yet in a develop-
mental stage, especially in those examples where there is a
tendency to show a compound character, but the conditions,
also, may be different owing to the absence of any modifying
influences which action may bring to bear upon it.

THE LuMBAR PLEXUS.

The two plexuses were of ordinary type, and were alike,
except that an extra communicating loop passed from the
Second to the Third nerve on the left side, and that the First
nerve on the right side was smaller than that on the left. On
neither side was there a communicating loop from the Twelfth
Thoracic to the First Lumbar nerve.

THE ILIO-HYPOGASTRIC NERVE.

On the right side, this nerve was given off from the Twelfth
Thoracic. The Twelfth Thoracic nerve was larger than that of
the left side. It gave off two iliac branches, and divided into
two branches which ran along the anterior abdominal wall.
The lower branch corresponded to the LIlio-hypogastric nerve.
The upper branch was the Twelfth Thoracic proper.

The Llio-hypogastric nerve coming off in common with the
last Thoracic is not unusual. Schmidt (1, a) described this
arrangement in one out of three or four bodies. In such a case
the Ilio-inguinal was larger than usual. It may come not only
from the Last Thoracic, but may also get a small root from the
Eleventh Thoracic (Quain, 2, a). There may be certain degrees
of reciprocal development between the Last Thoracic and the
lio-hypogastric nerves, so that when the one is large the other
is small or absent (Macalister, 3, a).

268 MR EDWARD B. JAMIESON.

THE AccEssoRY ANTERIOR CRURAL NERVE.

When the anterior surface of the Psoas muscle of the right
side was exposed, two nerves were seen lying on its surface.
The internal nerve was the Genito-crural. The external, a
much larger nerve, ran down on the surface of the Psoas, cross-
ing obliquely outwards to join the Anterior Crural nerve a
short distance above Poupart’s ligament. Some of its fibres.
entered into the substance. of that nerve, but the bulk of it was.
merely bound down to the Anterior Crural by the fibrous tissue
of the nerve-sheath. The lower limb of the right side had been
removed some time before this dissection was commenced, and
this nerve could not be traced beyond Poupart’s ligament. On
tracing it back through the Psoas to its origin, it was seen to be
formed by two pieces, of which the upper and more slender
piece arose from the Second Lumbar nerve shortly after it had
been joined by the communicating branch from the First; the
lower, larger piece, from the Second nerve at its junction with
the root of the Anterior Crural from the Third nerve. “The two
pieces came forwards independently through the substance of
the Psoas, and united as soon as they reached its anterior
surface.

Winslow (4, a) described a nerve similar to this, but with a
slightly different origin, and he called it an accessory or com-
panion nerve to the Anterior Crural (“ On le peut regarder commé
LT Accessoire ow L’ Associé du Nerf Crural”). It was given off by
the Third Lumbar nerve, ran down between the Iliacus and the
Psoas, and joined with the Anterior Crural nerve to the outer
side of the Psoas. Schmidt (1, d) described the plexus of Martin
and Gunther, which he found twice in seven bodies. One of
the two varieties of this plexus, which he mentioned, is similar
to the nerve I have described:—A considerable branch came
from the union of the communicating loops of the first three
Lumbar nerves before the Third joins the Fourth, and lower
down united with the Anterior Crural. Schmidt also mentioned
a branch described by Vieussens (1, ¢), which sprang from the
Third Lumbar nerve and joined the Anterior Crural in two
pieces. In each of these three cases there is a certain similarity
to the nerve I have described, but in none of them is there the

se
bat eS

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF FaeTUS. 269

precise mode of origin, nor does any of them bear the same
relation to Psoas.

THE MIDDLE AND EXTERNAL CUTANEOUS NERVES.

On the left side there was no separate, distinct External
Cutaneous nerve. Both External and Middle Cutaneous nerves
were given off directly from the Second Lumbar by a number of
roots, which combined in the substance of the Psoas to form
three nerves. These pierced the Psoas and lay on its anterior
surface, so that when this muscle was exposed five nerves were
seen lying on its surface, the two most internal being the two
divisions of the Genito-crural nerve. The three nerves ran

down over the Psoas, inclining to its outer side, till they lay on

the Anterior Crural nerve behind Poupart’s ligament. Through-
out their course they communicated with each other by many
very fine nerve-filaments. Behind Poupart’s ligament the outer-
most nerve divided into an outer, larger branch, which took the
place of the posterior division of the External Cutaneous, and
an inner branch which joined the middle nerve. The nerve
formed by this union represented the outer branch of the
Middle Cutaneous. The innermost nerve divided above
Poupart’s ligament into two equal branches. The outer supplied
the place of the anterior division of the External Cutaneous,
the inner represented the inner branch of the Middle Cutaneous.

An arrangement of the External and Middle Cutaneous
nerves of the thigh precisely like the foregoing I do not find
recorded, but, at different times, arrangements bearing some
resemblance have been met with. Winslow (4, 4) described two
nerves which arose from the Second Lumbar nerve, and having

pierced Psoas at different places, ran downwards and passed out
_under the upper part of the Fallopian ligament, uniting as they

did so to form one nerve. This nerve divided into branches
which were distributed to inguinal glands, to crural aponeurosis,
and to the front of the thigh as far as the knee. Some united
with branches of the Anterior Crural; others went to the inner
side of the thigh; one accompanied the Crural artery.

Schmidt (1, @) described various communications between the
Middle and External Cutaneous nerves, and instances of these

VOL, XXXVII. (N.S. VOL. XVII.)}—APRIL 1903, 19

270 MR EDWARD B. JAMIESON,

nerves arising in the abdomen:—He had seen the Middle
Cutaneous springing from the second ansa of communication,
and had seen it joining a branch of the External Cutaneous. He
had also seen the External Cutaneous sending a branch to join
the Middle Cutaneous. He had further observed the Anterior
Cutaneous, «¢. the inner division of the Middle Cutaneous,
arising from the ansa of the Third pair; piercing the Psoas, it
ran down over it, and passed under Poupart’s ligament to be
distributed to the thigh. The External Cutaneous nerve
frequently accompanies, or is united with, the Anterior Crural
nerve to below Poupart’s ligament (Quain, 2, 0); this was also
seen by Schmidt twice in about thirty cases. The posterior
branch of the External Cutaneous may be replaced by a branch
from the Genito-crural nerve (Quain, 2, 0).

THE ACCESSORY OBTURATOR NERVE.

Origin.— An Accessory Obturator nerve was found on the
left side arising from the Third Lumbar nerve. Its apparent
origin was from the angle between the roots to the Anterior
Crural nerve and the Obturator; but having been traced back-
wards, it was found to turn round behind and below the
Obturator part of the nerve, and to arise from the front and
inner side of that portion; and all its fibres came from this
Obturator portion.

Course.—It ran downwards behind Psoas towards the pelvic
brim, and then along the pelvic brim behind the Inner border
of Psoas, external to the Obturator nerve. It crossed the
public ramus in close contact with the inner border of the
Psoas behind the external iliac vein, and passed behind the
Pectineus and afterwards the Adductor Longus. Lying there
in front of Obturator Externus and Adductor Brevis, it had the
anterior division of the Obturator nerve to its inner side, and
was crossed, anteriorly, by the branch of that nerve to the
Adductor Longus. It appeared at the inner border of the
Adductor Longus about its middle, and continued downwards
along the inner border of the Adductor Longus until that
muscle was crossed by the Sartorius. Thence it passed under
cover of Sartorius, and crossed obliquely in front of the lower

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF FaTus. 27]

and inner part of the fibrous roof of Hunter’s canal. The Long
Saphenous nerve, immediately after its emergence from under-
neath the fibrous roof of Hunter’s canal, crossed in front of it
as it lay under Sartorius. It appeared at the anterior border
of the Sartorius at the level of the adductor tubercle, and
having pierced the deep fascia, it ran forwards and downwards
in the superficial fascia towards the patella.

Branches.—While it lay on the Os Pubis it gave off a branch
which passed directly outwards, to end in the capsule of the
hip-joint behind Psoas. While it lay behind Pectineus, and in
front of Obturator Externus, it gave off one small branch which
passed directly backwards, crossing the anterior division of the
Obturator nerve externally, to join the posterior division of the
Obturator nerve. This branch was traced to the Adductor
Magnus. A little below it gave off another small branch which
passed backwards, crossing the branches from the Obturator
nerve to the Adductors Longus and Gracilis and the Obturator
branch to the Pectineus, on their outer side, and joined the
branch from the anterior division of the Obturator nerve to the
Adductor Brevis. While it lay behind the Pectineus, and in
front of the Adductor Brevis, it gave off an exceedingly slender
branch which passed inwards behind the nerve to the Adductor
Longus, and joined the nerve to the Gracilis. While it lay
along the inner border of the Adductor Longus, two very slender
branches were given off close together, which passed forwards,
and having appeared at the anterior border of the Gracilis,
united with a branch of the inner (or posterior) division of the
Internal Cutaneous branch of the Anterior Crural nerve. While
it lay under cover of the Sartorius, a slender branch from it
passed downwards and backwards to unite with the inner
division of the Internal Cutaneous at the posterior border of
the Sartorius; several delicate filaments passed between it and
the Long Saphenous nerve; and one filament was given off and
passed downwards to end in the femoral artery as it passed
through the opening in the Adductor Magnus. The terminal
filament, in front of the Sartorius, was exceedingly fine; but it
could be traced forwards to the inner side of the patella, where
it divided into two branches, the upper of which passed directly
outwards over the patella, while the lower passed downwards

272 MR EDWARD B. JAMIESON.

and outwards along the border of the patella. It supplied no
branch, directly or indirectly, to the Adductor Longus, and
none to the Pectineus. No cutaneous branch was given off by
the Obturator nerve.

An accessory Obturator nerve of the same dimensions, but
with a slightly different origin, was found on the right side. It
was formed by two roots, both connected with the Obturator
nerve. The main root came from the Third Lumbar nerve, out
of the midst of the root of that nerve to the Obturator; this
was joined by a small filament from the Obturator root from
the Second nerve, as it crossed the Third nerve. It followed
the same course as the Accessory Obturator on the left side.
Owing to the previous removal of the lower limb of the right
side all the distribution could not be followed, but sufficient
had been left to show a branch given off to the front of the
capsule of the hip-joint, a small communicating twig to the
posterior division of the Obturator nerve, a larger communica-
tion to one of the branches of the anterior division of the
Obturator nerve, and the cut end of what remained of the
nerve.

ResuME oF Previous DESCRIPTIONS OF THE ACCESSORY
OBTURATOR NERVE.

Frequency.—Schmidt (1), who claimed to have been the first
to mention and describe the Accessory Obturator nerve (§ x1. :
“ Nervus quidam, hucusque nemini notus”; and § xxix.: “ Nee
non nervum ante me & nemine descriptum, utpote N. ad nervum
eruralem internum, seu obtwratorium, accessortwm”), found it
four or five times in nine or ten bodies. Eisler (5) found it in
29 per cent. of cases. Paterson (6), out of twenty cases, found
it in three. .

Origin—In its origin the nerve shows no constancy, but its
variations are within certain limits. It is commonly described
as arising from the Third and Fourth Lumbar nerves, in
association with the roots of the Anterior Crural given off by
these nerves (Quain, 2,¢; Gray, 7). In the cases described by
Paterson, it sprang from the Third nerve in association with the
root of the Anterior Crural nerve. An occasional origin from
only the Third Lumbar nerve is mentioned in Quain (2, ¢). It

— a

_ ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF FETUS. 273

may arise from the Fifth Lumbar nerve as well as from the
Third and Fourth (Quain, 2, ¢). It may be given off from the
trunk of the Obturator nerve (Ellis, 8). It is represented in
three of the figures appended to Schmidt’s commentary (1), and
in each it has a different origin. In Table I. fig. 4 it comes out
of a plexiform arrangement of the roots of the Obturator from
the Third and Fourth Lumbar nerves; in fig. 5, it comes from
the root to the Anterior Crural from the Third Lumbar nerve,
and, by a slight communication, from the root to the same nerve
from the Fourth, and also from the root from the Third Lumbar
nerve to the Obturator. In Table II. it arises from the Third
and Fourth Lumbar nerves before the Obturator and Anterior
Crural nerve-roots have been given off.

Distribution —In its distribution the Accessory Obturator
nerve is very erratic, ranging from a minimal distribution to
one structure to an extensive supply of muscles and skin of the
inner side of the thigh. In the majority of instances it is
distributed to the hip-joint, the Pectineus, and, by a communi-
eating branch, to the superficial division of the Obturator nerve.
When small, it may expend itself on the capsule of the hip-joint
(Gray, 7, a), or it may supply nothing beyond the Pectineus;
this supply may be complementary to the branch to the
Pectineus from the Anterior Crural, or it may replace that
branch (Paterson, 6, 9). When slightly larger, it supplies a
branch to the hip-joint and a communicating branch to the
Obturator nerve (Schmidt, 1, ¢). A still larger nerve gives the
usual three branches. The communicating branch to the
Obturator may, when traced out, be found to furnish supply to
the Adductor Brevis, the Adductor Longus, the Gracilis, and,
rarely, a cutaneous branch to the inner side of the thigh (Quain,
2, ¢). The most extensive distribution I find recorded was
described by Paterson (10) in the case of a Negro, where an
Accessory Obturator nerve was found. It arose from the Third
Lumbar nerve, and gave branches as follows:—(1) to the
Pectineus; (2) to join the nerve to the Gracilis; (3) to join the
nerve to the Adductor Brevis; (4) to join the cutuneous branch
of the Obturator, and through that, communicated with the
internal cutaneous branch of the Anterior Crural and with the
Long Saphenous nerve; (5) to the hip-joint; (6) to join the

274 MR EDWARD B. JAMIESON.

posterior division of the Obturator, and through that, supplied
branches to the Obturator Externus, to the Adductor Magnus,
and to the knee-joint. The distribution of this nerve compares
very closely with that of the one I have described, the differences
consisting in that in this nerve it gave branches to the Pectineus,
to the Obturator Externus, and to the knee-joint, and gave no
branch to the femoral artery ; and it gave only a contribution to

Ant Cr

Fie. 1.—Right side. TZ.aii., the last thoracic nerve. J.J. to V., the lumbar
nerves. Ii.,J,, the iliac branches of the last thoracic and the ilio-hypo-
gastric nerves. J1.-Hy., the ilio-hypogastric nerve coming off ‘the last
thoracic. i.-Zn., the ilio-inguinal nerve. G.-Cr., the genito-crural nerve.
£.C., the external cutaneous nerve of the thigh. A. Ant.Cr., the accessory
anterior crural nerve. Ané.Cr., the anterior crural nerve. 4.Ob., the
accessory obturator nerve. -Ob., the obturator nerve. JZ.S.C., the lumbo-
sacral cord.

the cutaneous branch of the Obturator nerve, whereas, in the
case I have described, the cutaneous nerve was wholly from the
Accessory Obturator.

Paterson (6) has shown that the Accessory Obturator nerve,
with three branches as commonly found, would be better named
the Accessory Anterior Crural, on account of its origin and
distribution. But in instances where the nerve is given off from

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF F@TUS. 275

the roots of the Obturator nerve, or takes on a supply which is
generally to be referred to the Obturator, this name is inappli-
cable. There are, at least, three forms of so-called Accessory
Obturator nerve, all passing over the pubic ramus internal to
the Psoas :—1. The suprapubic nerve, large or small, which keeps

Tx

MC. ead £

Fic. 2.—Left side. TZ.xii., the last thoracic nerve. Z.J. to V., the lumbar
nerves. J/., the iliac branch of the last thoracic nerve. J/.-Hy., the ilio-
hypogastric nerve, J/.-Zn., the ilio-inguinal nerve. G.-Cr., the genito-
crural nerve dividing into its genital and crural branches. £.C. and J1.C.,
the external and middle cutaneous nerves of the thigh: the two terminal
branches nearest mid-line representing the middle cutaneous; the two
terminal branches furthest. out representing the external cutaneous.
Ant.Cr., the anterior crural nerve. A,Ob., the accessory obturator nerve.
Ob., the obturator nerve. Z.S.C., the lumbo-sacral cord. [Figures 1 and 2
were drawn for me by Dr Hepburn.]

within the limits of the Obturator nerve distribution. 2. The
suprapubic nerve, for which Paterson has suggested the name
Accessory Anterior Crural, 3, The suprapubic nerve, consisting
of the nerve to the Pectineus and part of the Internal Cutaneous
branch of the Anterior Crural nerve, which, according to

276 MR EDWARD B. JAMIESON.

Macalister (3), is misnamed Accessory Obturator. I doubt if
any single, yet sufficiently comprehensive, name could be devised
to include all of these; and a multiplication of names for an
inconstant nerve to indicate all its vagaries would be of
questionable advantage. The term Accessory Obturator nerve
may, strictly speaking, be insufficient or incorrect; but, by
convention, what is understood by that term is an inconstant
nerve, with an origin varying within limits, which passes over
the horizontal ramus of the pubis internal to the Psoas, and has
a varying distribution in association with the Anterior Crural,
or the Obturator nerve, or both; and a changing of its name into
one which is not more comprehensive is unnecessary.

THE SACRAL PLExus.

This plexus, on both sides, both in its formation and in the
nerves given off from it, was conspicuously normal.

THE BILAMINAR MuscuLus PECTINEUS.

Description.—The Pectineus consisted of two separate lamine,
an anterior or superficial and a posterior or deep. The anterior
lamina took origin by fleshy fibres from the pectineal line and
the surface of the horizontal ramus of the pubis below. It was
of equal breadth throughout; towards the insertion it became
tendinous, and was inserted into the posterior surface of the
shaft of the femur behind the lesser trochanter, and into the
upper part of the line leading down from the lesser trochanter
towards the linea aspera. The posterior lamina was less thick
than the anterior, and was narrower, especially at the origin,
but it was fleshy throughout. It took origin from the front of
the body of the pubis, immediately below the crest, and external
to the Adductor Longus, and from a small part of the adjoining
anterior surface of the horizontal ramus subjacent to the
anterior lamella. From its origin it passed downwards, out-
wards and backwards behind the anterior lamina, to be inserted
into the line leading down from the lesser trochanter, but falling
short of the lower limit of attachment of the antérior lamina.
As the inner border of the posterior lamina projected inwards
beyond the anterior lamina at the origin, and the anterior

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF Fa@TUS. 277

_ projected beyond the posterior at the insertion, the fibres of the
anterior lamina crossed those of the posterior at an acute angle.
The Adductor Longus was very closely adjacent to the posterior
lamina at the origin and for some little distance beyond, but
towards the insertion it was separated by a considerable interval
from both lamin.

Digest of previous descriptions of variations in the Pectineus.—
Although the Pectineus presents, as a rule, no peculiarity, yet
it is subject to frequent variations, and those of different kinds.
Two forms of variation have been described which affect only
itself, and other variations have been described which implicate
neighbouring muscles, commonly those of the Adductor group.

Variations affecting itself are those in which the Pectineus is
found divided, completely or incompletely, into two, and the
splitting as described by Testut (11) may be in a direction such
as to produce either two pieces lying side by side on the same
level, or two lamine or strata, one placed in front of the other.
The latter condition seems to be the more common variation ;
and in Henle’s Anatomy (12) it is regarded as the normal,
though not constantly present. The Pectineus is described as
consisting usually of two strata, which are separable externally,
but joined internally, and united at the insertion. The origin
of the deeper layer extends further inwards over the os pubis,

hence the fibres of the two layers cross at an acute angle.
_ This corresponds very closely to the arrangement found in the
specimen I have described, the difference consisting only in the
degree of separation. One does not find this double arrange-
ment very often in the dissecting-room, though in many cases,
especially in the lesser degrees of separation, it may. be over-
looked. Paterson (6) describes the muscle as occasionally
consisting of two incompletely separated muscular strata.
Winslow, in the copy of his Exposition (13) which I have seen,
stated that he had seen the Pectineus double (“Je /’ai aussi
trouvé double’), but the relative positions of the two divisions is
not specified. In another edition or separate work (14) referred
to by Testut and Macalister (15, a), it is stated that he had
seen a bilaminar Pectineus.

The other condition of splitting has been described by Testut,
who states that the Pectineus may sometimes be found in two

278 MR EDWARD B. JAMIESON.

~

pieces on the same level, separated by an interval almost to its
insertion. Macalister (15) has “seen it cleft into two parts,”
and mentions that this has been “also seen by Sémmering.”
In Quain’s Anatomy (16) this variation is mentioned also, the
Pectineus being divided into inner and outer parts.

Other variations consist in different degrees of admixture of
the fibres of the Pectineus with fibres of other muscles, or of
slips of fleshy fibres passing between the Pectineus and other
muscles, principally those of the Adductor or Obturator nerve
group. Winslow (14), in his description of the Pectineus, said
that it mingled with fibres of the Adductor Longus at its origin,
and with fibres of the Adductor Brevis at its insertion. Sir
Wm. Turner (17) has described, in the case of a Negro, a mus-
cular slip, three inches long, which arose from the inner border
of the Pectineus, and joined the tendon of the Adductor Longus.
Testut (11), later, described similar instances. He observed in
two cases a fleshy bundle of fibres separate itself from the
Pectineus shortly after its origin, and mix with the fibres of the
Adductor Longus near the linea aspera. Macalister (15) has
also seen a slip from the Pectineus passing over the Profunda
femoris artery to join the Adductor Longus, and likewise fibres
from the Adductor Longus to the Pectineus. He has also seen
the Pectineus sending a slip to the Obturator Externus.

In the body prosected this session for the systematic course of —
lectures delivered by Sir William Turner, there was found a
fleshy slip which separated itself from the inner border of the
Pectineus near its origin, and blended with the Adductor Brevis
on its anterior aspect near the upper border, close to its
insertion,

Of connection with any other muscle, outside the Obturator
group, I find only one instance, which is mentioned by
Macalister (15, a), who has seen a slip from the Iliacus joining
the Pectineus.

There are slight variations in the extent and position of the
insertion of the Pectineus, ¢g. partial insertion into the front of
the capsule of the hip-joint (Macalister, 15, a). This may have
some bearing on the theory of Bland Sutton (18) that the
ligamentum teres is an evolutionary regression of part of the
Pectineus muscle.

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF F@TUS. 279

Comparative Analomy.—Among mammals different varieties
of the Pectineus muscle are found, and in certain monkeys
variations have been found in the same species. In Cercopi-
thecus and in the Chimpanzee (Troglodytes niger) Testut has
several times seen a double Pectineus, and he describes the
arrangement in the Chimpanzee; the two portions lay side by
side, and were separated by a linear interval, which narrowed
as they approached the femur. The Femoral artery lay
on the outer head, while the Femoral vein lay along the
interstice. This is almost identical with the condition of
the Pectineus in the human subject in the second form of
variation.

In some other mammals this is described as the constant
arrangement. In the Raccoon (Nyctereutes procyonoides) the
Pectineus has two heads, a long inner and a shorter outer
(Meckel, 19). In Echidna also the Pectineus has two heads
lying on the same level, an inner and an outer. Both come
from the pectineal line, and the inner also from the symphysis
pubis, and they are inserted into the Femur as far down as the
third trochanter (Alix, 20). In some other mammals the
muscle is single at its origin, and divided into two parts towards
the insertion, unlike the arrangement of the split Pectineus in
Man, where the tendency is towards division at the origin and
union towards the insertion. In the Ox (Bos taurus) the muscle
is single at the origin, but divides into two parts towards the
insertion, the upper division being inserted into the upper part
of the posterior surface of the shaft of the Femur, the lower
extending as far down as the condyle (Chauveau, 21, a). In the
Pig (Sus domesticus) the muscle is similar to that of the Ox. In
the Koalo (Phascolarctos cinereus) and Opossum (Didelphys
virginiana) the muscle is similar to that of the Ox, but the
insertion is less extensive. It arises by a single rounded head,
but divides after its origin, and is inserted as far down as the
middle of the shaft of the Femur (Young, 22). In the Elephant
(Hlephas indicus) the mixture with fibres of another muscle is
seen. The Pectineus takes origin between the Ilio-pectineal
eminence and symphysis pubis, some of its fibres being closely
connected with those of the Adductor Longus (Miall and
Greenwood, 23). In the Horse (Zqwus caballus) the arrange-

280 MR EDWARD B. JAMIESON.

ment at first sight may perhaps suggest bilaminarity. It is
described by Chauveau (21, 0) as bifid at its origin, with the
Pubio-femoral ligament passing between the two parts. But
the degree of bifidness only consists in that the Pubio-femoral
ligament, passing through it near its origin, must have certain
muscle fibres on the one side and certain on the other, while
certain muscle fibres arise from the ligament. Ellenberger and
Baum (24) do not describe it as even bifid; and Bland Sutton
regards the Pubio-femoral ligament as part of the Pectineus
itself which has undergone regression.

Nerve-supply. — Although the Pectineus under description
got no branch from the Accessory Obturator nerve which was
present, yet it got an Obturator supply by a branch which was
given off from the inner side of the anterior division of the —
Obturator nerve, immediately after it had separated from the
posterior division, and before it was joined by the communi-
cating branch from the Accessory Obturator. The muscle also
got the normal nerve-supply from the Anterior Crural. The
branch from the Obturator passed downwards, outwards and
forwards behind the nerve to the Adductor Longus, and in front
of the nerve to the Adductor Brevis, and entered the deep
surface of the posterior lamina about its middle. The branch
from the Anterior Crural nerve was given off immediately
below Poupart’s ligament, followed the usual course, and entered
the anterior lamina on its superficial aspect. In accordance
with the relative size of the two lamin, the branch from the
Obturator was the smaller from the beginning; and it further
reduced itself in size by giving off two very minute filaments
to the Adductor Brevis before entering the Pectineus. No
filaments of either nerve could be traced across from one
muscular lamina to the other. iy

Relation to Nerve in Man.—The Pectineus, as a single muscle,
is commonly supplied from the superficial division of the
Anterior Crural nerve by one or two branches. One of the
two branches may be given off in the abdomen and join the
Accessory Obturator nerve (Gray, 7, 0). It is also in some
cases supplied from the Obturator nerve. Winslow (4, c)
described a branch from the Obturator as of usual occurrence,
but in his Exposition nerves are sometimes given a wide dis-

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF FmTus. 281

tribution, ¢.g. the Anterior Crural nerve, to which was referred
the supply not only of the Extensor muscles, but the Adductors
and the Semitendinosus as well (4, d). In modern text-books a
branch from the Obturator nerve is described as of occasional
or of rare occurrence (Gray, 7, a; Macalister, 3,b; Cunningham,
25). The supplementary nerve-supply may come from the
Accessory Obturator nerve when that is present (Ellis, 20),
but this is not always the case. Schmidt (1, a) described a
branch from the Accessory Obturator when that nerve was
large. In Cunningham’s Manual it is said to be very rare to
find a branch from the Accessory Obturator nerve to the
Pectineus. But in some cases the Accessory Obturator nerve
may supply nothing but the Pectineus, and the branch from the
Accessory Obturator to the Pectineus may be the exclusive
nerve-supply of the Pectineus (Paterson, 6, 9). When the
Pectineus is a double muscle, a separate nerve is given to each
part. The inner or deeper part is supplied from the Obturator,
the outer or superficial part is supplied from the Anterior
Crural nerve (Quain, 16; Paterson, 6). I do not find described
a branch coming from the Obturator nerve to the Pectineus
when the Accessory Obturator nerve is present.

Relation to Nerve in other Mammals.—In mammals, so far as
I have read descriptions of the relation of the Pectineus to
-nerve-supply, the Pectineus is supplied from either the Anterior
Crural or from the Obturator, but in several cases I have not
been able to obtain access to an account of the nerve-supply to
the muscle, either normal or abnormal. In the monkey, how-
ever, the nerve-supply, as in Man, is from the Anterior Crural
nerve. In the Gorilla (Troglodytes Gorilla), Orang (Simia
Satyrus), Gibbon (Hylobates lar), and Chimpanzee (7'roglodytes
miger), Hepburn (26) could find no branch from the Obturator
to the Pectineus. In Macacus rhesus, a large number of which
was examined by Sherrington (27), no Obturator supply to the
Pectineus was found. In the Rabbit (Lepus ewniculus), the
nerve to the Pectineus is from the Crural nerve (Krause, 28).
In the Dog (Canis familiaris) the nerve-supply is from: the
Obturator nerve (Ellenberger and Baum, 29). In the Ox and
Pig, where the Pectineus is divided towards its insertion, the
nerve-supply is wholly from the Obturator (Chauveau, 21). In

282 MR EDWARD B. JAMIESON.

the Horse also the nerve-supply is exclusively from the
Obturator nerve (Chauveau, 21; Ellenberger and Baum, 24).

CONCLUSIONS.

Taking into consideration the occasional occurrence of the
Pectineus divided into two more or less distinct parts, each
carrying with it a nerve-supply from different nerve-trunks, and
that the Pectineus sometimes occurs as a single muscle with a
double nerve-supply, if one may take nerve-supply as a guide,
one is led to accept the view of Paterson that the two parts
belong morphologically to the two different muscle-groups
supplied by these two nerve-trunks, and that the single muscle,
when it gets a double nerve-supply, does so in virtue of its
compound character. This view is upheld by the occasional
mixing of the fibres of the Pectineus with those of muscles of
these groups, especially with those of the Obturator nerve
group, either at the attachments of the muscles or by fleshy slips
passing from one muscle to another. (It is unfortunate that in
those cases where a fleshy slip passed either to or from the
Pectineus, connecting it with other muscles, the nerve-supply
could not be found and noted, as well as in the cases where the
Pectineus is divided into two parts.) Further, at some remote
antecedent time, the Pectineus may have normally consisted of
these two parts completely fused, while each part retained its
original nerve-supply as is now the case in the Brachialis
Anticus of Man: and instances of the reappearance of that
condition might be regarded as historical reversions. More-
over, since the Pectineus in certain mammals is normally
supplied, exclusively, by one or other nerve only, one is led to

think that the part belonging to one muscle-group may be.

developed to the exclusion of the other part, which is either
lost, or may have rejoined the original muscle-group, or, follow-
ing up the suggestion of Bland Sutton, may have undergone
regression into a ligamentous structure, ¢g. the pubio-femoral
ligament in the Horse, the ligamentum teres in Man. A
difficulty, perhaps not serious, presents itself here; that in one
set of mammals one part has undergone regression, and in
another set the other part; while one would expect, 4 priori at

ee aed | Ce

iit
=

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF FETUS. 283

any rate, that there would be more constancy in the selection of
the part which should remain muscular. It is possible that in
some mammals there exists, as a normal condition, a Pectineus
divided into two components, or fused into one with a double
nerve-supply ; though, in those of which I have read descriptions,
a single nerve-supply is the rule, indicating the complete exclu-
sion of one of the two divisions of the muscle. In the Ox and
the Pig the Obturator nerve portion only is present. The division
into two parts is towards the insertion, and the muscle is not
in the same class of case as the occasionally divided Pectineus
of Man. From the point of view here considered, it may be re-
garded as accidental, possibly resulting from the greater extent
of attachment to the shaft of the femur; or it may be that a
part of it represents the Adductor Longus of Man. In the Dog
and the Horse the Pectineus belongs to the Obturator nerve-
group also. Ellenberger and Baum indicate that this muscle
may, in part at any rate, be the representative of the Adductor

_ Longus of Man. Chauveau regards the portion which lies in

the plane superficial to the pubio-femoral ligament as the homo-
logue of the Pectineus in Man. If this is so, it would correspond
to the portion of the Pectineus of Man which is commonly
absent, i.e. the Obturator nerve portion. In the Rabbit, in
Monkeys, and in Man the part belonging to the Anterior Crural
nerve-group of muscles predominates, generally to the complete
exclusion of the other part. In Man the normal Pectineus is
morphologically a segmentation from the Iliacus (Macalister, 3, ¢),
and is probably so in the Rabbit and Monkey. But in Man, as
a greater number of human subjects, through course of time, has
been dissected and examined than of any other species of
mammal, transition stages of the exclusion of part of the double
muscle have been seen and noted. As the Anterior Crural
nerve portion is the constant portion in Man, one may expect to
see, as is the case, the transitions taking place not in it, but in
the Obturator nerve portion:—Firstly, there is the original
fused condition of the two different portions seen in the small
percentage of cases where the Pectineus muscle, while consisting
apparently of one single undivided stratum, gets branches of
supply from both the Anterior Crural and the Obturator nerves
Next in order comes the condition in which there is a deeper or

284. MR EDWARD B. JAMIESON.

internal inconstant portion, showing greater or lesser degrees of
separation from the other portion, and supplied by the Obturator
nerve. Thirdly, there is the union between the Pectineus and
the Adductors Longus and Brevis and Obturator Externus,
effected by slips of fleshy fibres passing from one muscle to the
other, representing an imperfected attempt of a portion of one
muscle to join wholly with the other. The process is nearly
complete in those cases where there is merely the mixture of
fibres of the Pectineus with those of the Adductor Longus at the
origin, and with the Adductor Brevis at the insertion. Finally,
there is the condition which is usually found; the Pectineus is
separate and single, and has but the one nerve-supply.

The opposite assumption is tenable likewise: that the muscle
is on the evolutionary road to become a compound muscle, and
the series of steps, as seen in the variations, could be traced in
the opposite direction, from the simple to the compound. The
slips between the Pectineus and the Adductors would bear the
same significance as portions of the Brachialis anticus joining .
the Supinator longus in the upper limb, such as have been
described by Macalister (15, 6), and of which I have seen two
examples in different bodies during the last Winter Session. In
support of this assumption there was the presence of a bilaminar
condition of the Pectineus in a foetus, constituting one of the
stages of the development towards a fused compound Pectineus.
This might have gone on pari passu with the development of
the foetus until at birth at full time, or in the adult state, the
condition of complete fusion with a double nerve-supply would
have been present. Considering the close association of the two
laminz and the age of the foetus, it is more likely that it
represents a stage in the inclusion of an Adductor portion into
the Pectineus, rather than a stage in the separation of the
Adductor element of the Pectineus, which might, at a later date,
fuse with the Adductors proper. Less attention has been directed
to the muscular than to any other system in the foetus; other-
wise, in muscles like the Pectineus, abnormal conditions,
representing transitory phases in development, might more
frequently be met with. The compound Pectineus differs,
however, from the compound Brachialis anticus in being only
occasionally present, and therefore anomalous ; and anomalies are

ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF F@TUS. 285

rather to be classed as historical retrogressions than as
evolutionary progressions.

The case described by Macalister, where the Iliacus gave a
muscular slip to the Pectineus, is obviously one of an incomplete
segmentation of the Pectineus from the [liacus; and a com-
parable condition would be a slip passing from, say, the Adductor
longus to the inner or deeper division of a divided Pectineus, or
to an undivided Pectineus with a double nerve-supply.

The presence of an Accessory Obturator nerve, supplying part
or whole of the Pectineus, offers no impediment to the view that
the Pectineus may be a compounded muscle. In the cases
where it takes on the whole supply, it is given off from the roots
of the Anterior Crural nerve, as Paterson has pointed out; and
it practically amounts to an intra-abdominal origin of the nerve
to the Pectineus from the Anterior Crural, similar to that
described in Gray’s Anatomy as joining the Accessory Obturator,
and that described by Macalister, given off within the abdomen
with the Internal Cutaneous nerve. In those cases where the
Accessory Obturator comes from the roots of the Obturator
nerve and supplies the Pectineus, it would merely signify an
intra-abdominal origin for the Obturator branch to the Pectineus,
similar to that of the Anterior Crural, and the Pectineus, in such
& case, is a muscle made up of two parts.

REFERENCES TO LITERATURE.

(1) Scumrvt, J. A., Commentarius de Nervis Lumbalibus eorumque
Plexu, Anat.-Path., Vindobonnae, 1744, a, § xxiii. ; b, §xxxvii. Tab.
i. fig. 1, aaa.; c, §xxvii. ; d, §§ xxx. and xxvii. and xxxi. ; e, §xl.

(2) Quain’s Anatomy, vol. iii. pt. ii., 10th edition, a, p. 315;
5, p. 317; ¢, p. 319.

3) Macauister, A., Text-book of Human Anatomy, 1889, a, p.
467 ; b, p. 493; ¢, p. 490.

(4) Wixstow, J. B., aposition anatomique, T. iii., Traité des
Nerfs, a, p. 205; b, p. 203; «, p. 206; d, p. 210.

(5) Erster, P., Der Plex. Lumbo-sacral des Menschen, Halle, 1892
(referred to in Quain’s Anatomy).

(6) Parerson, A. M., “The Pectineus and its Nerve Supply,”
Journ. of Anat. and Phys., vol. xxvi. p. 43.

VOL, XXXVII. (N.S. VOL. XVII.)—APRIL 1903. 20

286° ANOMALIES IN NERVES FROM LUMBAR PLEXUS OF FQTUS.

(7) Gray’s Anatomy, 14th edition, a, p. 841, figs. 508 and 509;
b, p. 843.

(8), Euuis, Demonstrations of Anatomy, 11th edition, a, p. 543 ;
b, p. 631.

(9) Parerson, A. M., Teaxt-book of Anatomy, edited by D. J. Cun-:
ningham, 1902, p. 605.

(10) Parerson, A. M., “Origin and Distribution of Nerves of the
Lower Limb,” Jour. Anat. and Phys., vol. xxviii. p. 99, foot-note.

(11) Txsrut, L., Les Anomalies Musculaires Chez L’ Homme, Paris,
1884, p. 649.

(12) Hutz, J., Handbuch der systematischen Anatomie des Men-
schen, 1858, Bd. i. Abth. iii. p. 268.

(13) WINsLoW, J. B., Exposition anatomique, 1743, T. ii., Traité
des Muscles, p. 117.

(14) Winstow, Hap, Anat., T. i. p. 117 (referred to by Macalister
and Testut).

(15) Macauister, A., “ Muscular Anomalies in Human Anatomy,”
Trans. of Roy. Irish Acad., vol. xxv., Science, a, p. 112; 6, pp. 76,
99. “4

(16) Quain’s Anatomy, vol. ii. pt. ii, 10th edition, p. 257.

(17) Turner, W., “ Notes on the Dissection of a Negro,” Jour. of
Anat. and Phys., vol. xiii. p. 380.

(18) Buanp Surton, J., Ligaments: Their Nature et a
2nd edition, p. 67.

(19) MucKEL, Traité, d Anatomie Comparée, T. vi. p. 378 (referred
to by Testut).

(20) Autx, Bull. Soe. Philomatique, 1867, p. 206 (quoted by
Testut)

(21) Cuavveau, A., Traité @ Anatomie Comparée des Animauc-
Domestiques, 4me edition, Paris, 1890, a, p. 363; b, p. 358; ¢, p. 364.

(22) Youne, “The Muscular Anatomy of the Koala,” Jour. of
Anat. and Phys., vol. xvi. p. 235.

(23) Mratt and Greenwoop, “The Myology of the Indian Ele-
' phant,” Jour. Anat. and Phys., vol. xii. p. 280.

(24) ELLeNBERGER und Baum, Topographische Anatomie des Pferdes,
Berlin, 1893, Th. i. p. 188, fig. 55.

(25) CUNNINGHAM, D. ie Manual of Practical Anatomy, 1901, p.
243.

(26) Hepsurn, D., “Comparative Anatomy of the Muscles and
Nerves of the Limbs of Anthropoid Apes,” Jowr. Anat. and Phys.,
vo]. xxvi. p. 350. ek

(27) Suerrineton, “ The Lumbo-sacred Plexus,” Jour. Phys., vol.
xiil., p. 643.

(28) Krause, W., Die Anatomie des Kaninchens, 2te Auflage,
Leipzig, 1884, p. 339.

(29) "ELLENBERGER und Baum, Systematische wnd Topographische-
Anatomie des Hundes, Berlin, 1891, p. 847, fig. 81.

COMPLETE ABSENCE OF THE SUPERFICIAL FLEXORS
OF THE THUMB AND CONCURRENT MUSCULAR
ANOMALIES. By H. S. Hatt, B.A., Pembroke College,
Cambridge. (PLATE XXXII.)

A RECENT dissection of an upper limb in the Cambridge Uni-
versity Anatomy School exhibited a very anomalous condition.
of the musculature of the thumb.

The subject was a well-developed male; and when the time
came for removing the skin from the hand, it was noticed that
the thenar eminence was unusually lacking in prominence. A
small amount of dissection revealed the fact that this was due
to the complete absence of the superficial flexors of the thumb,
viz., abductor pollicis, opponens pollicis, and the superficial
head of flexor brevis pollicis. Consequently,on removing the
skin, the entire length of the metacarpal bone of the thumb was
displayed. Moreover, the short stout branch of the median
nerve, which in normal cases supplies these muscles, was in this
subject completely absent.

This condition has, I think, only once been recorded.!

The condition was unaccompanied by any hypertrophy of the
neighbouring muscles. The remaining thumb muscles were in
appearance quite normal. However, at a later stage in the
dissection, some additional peculiarities of musculature were
displayed.

The tendon of extensor ossis metacarpi pollicis was double, as
is not infrequently the case. From the external tendon a small
quadrilateral muscle some 15 mm. square passed transversely
inwards, and was implanted on to the superficial aspect of the
anterior annular ligament. The accompanying photograph
shows this muscle clearly. I have been unable to find any
recorded instance of a muscle exactly similar to this.

In view, however, of the frequency with which muscular slips
from the superficial group of thumb flexors (especially abductor
pollicis) are found with attachments to the tendon of extensor

1 Fromont, “ Anomalies musculaires multiples de la main,” Bull. de la Soc.
Anat. de Paris, Avril—-Mai, 1895, t. ix, fase. x. p, 395.

288 MR H. 8S, HALL.

ossis metacarpi pollicis, it is possible that this anomalous slip
was an aberrant representative of one or all of the missing
flexors. Unfortunately, the nerve supply to this anomalous
muscular slip could not be found. It is interesting to note that
this slip, together with the extensor ossis metacarpi pollicis, to a
certain extent provided a functional compensation of the missing
group. The resultant of the pulls of the two muscles is in-
dicated in the accompanying diagram. Thus the extensor ossis
metacarpi pollicis pulling, roughly speaking, in the line of the

‘ Metacarpal j \.
ey

ss a
Ss sane me -

Anc. ann, lig A Sra
yo
ikaw pull of. Le lendon of Ext. oss. met poll,
Yesultant .

forearm, and the anomalous muscle at right angles to this, the
resultant of these two would be equivalent to a muscle pulling
diagonally across the wrist in the direction of the arrow, as
shown in the diagram.

Further dissection exposed an additional slip of muscle fibres,
apparently arising from the fascial sheath of the tendon of
flexor longus pollicis, and distally connected with the tendon of
insertion of the indical lumbrical muscle.

A somewhat similar accessory muscle to the indical lumbrical
connected with the metacarpo-phalangeal ligament of the thumb,
and occupying the web between the index finger and thumb,
has been described by Arbuthnot Lane, and a slip from the
flexor longus pollicis to the first lumbrical muscle has been
noted by Wood and Macalister. But in neither of these cases

1 Jour, of Anat, and Phys., vol. xxi. p, 674.

Jour. of Anat. and Physiology, April 1903.) (Prats XXXII.

Mr H. S. Hatt.

ABSENCE OF SUPERFICIAL FLEXORS OF THE THUMB. 289

were any concurrent anomalies in the musculature of the hand
noted. .

From this we may either conclude that in our subject the
presence of the additional lumbrical slip was a mere coincidence,
and had nothing to do with the other peculiarities mentioned,
or else we may regard this extra lumbrical slip as being a dis-
placed slip of the superficial flexors of the thumb.

This is a point, I think, which cannot be definitely settled,
but in any case the presence of the extra lumbrical slip is
interesting.

In conclusion, it may be mentioned that the hand showed
.no signs of having received any injury. to account for these
anomalies. The superficial palmar arch was, however, com-
pletely absent.

The left hand of the same subject exhibited no abnormal
arrangement of the muscles.

A METHOD OF OBTAINING UNIPLANAR SECTIONS
WITH THE ORDINARY ROCKING MICROTOME.
By W. Sampson Hanp.ey, M.S. Lond., Surgeon to Out-
Patients at the Samaritan Free Hospital for Women and
Children.

THE greatest disadvantage of the ordinary Cambridge Rocking
_Microtome has always been that its sections, instead of being
-uniplanar, are segments of a cylinder.

If the piece of tissue to be cut is a large thin slice, having an
area, for instance, of a square inch, and embedded on the flat,
its peripheral part may be entirely sliced away before the
“knife begins to cut the central portion of the tissue, and it
may thus be quite impossible to obtain a section of the whole
area of the piece embedded.

Where the piece of tissue is thick enough to be ‘turned’ by
the knife to a smooth convexity before its edges are entirely
shaved through, a complete section of the whole area of the
piece is obtainable. But the section is so far from being
uniplanar if the piece is a large one that a serious distortion is
introduced which may obscure the relations and introduce
fallacies in the interpretation of the microscopic appearances.

These disadvantages have been remedied in the recently
introduced rocking microtome, in which the axis of rotation of the
rocking arm is at right angles to the edge of the razor, instead
of lying parallel to it as in the ordinary ‘ Cambridge
Rocker.’

Since, however, for many workers the latter may be the only
microtome available, it seems worth while to describe a way of
obtaining with this type of microtome uniplanar sections of
large area. I have not seen the method described, though
doubtless such a simple device may have occurred to many.

It essentially consists in embedding the slice of tissue to be
cut on a cylindrical surface, corresponding to the curve
described by the rocking arm of the microtome.

A squared block of paraffin, sufficiently large to contain the

at i
is
i=
aie

ae

ee ee

OBTAINING UNIPLANAR SECTIONS WITH ROCKING MICROTOME. 291

piece of tissue to be cut, is fixed on the rocking arm, with its
centre truly in the axis of the arm, with its upper edge

_ horizontal, and with its free surface forming a plane at right

angles to the axis of the arm. These points can be judged
with sufficient accuracy by the eye.

This pattern-block is now cut in the ordinary way until its
cut surface has acquired the convex cylindrical form, and
complete sections of it are being cut by the razor. It is now
dismounted, covered with thin tinfoil, and surrounded by a pro-
jecting rim of stamp-paper. A mould with a convex cylindrical
floor is thus produced, and into this plaster of Paris is poured
as it stands on a level surface.

When the plaster has set, it forms a square or oblong block
with one concave cylindrical surface. Tinfoil is swagged down
upon this surface, and the edges of the block surrounded
by a rim of stamp-paper. The embedding mould is now
ready.

The slice of tissue used is very thin, say not more than
Z-inch thick, for two reasons. First, since the sections are
uniplanar, very much thinner pieces may be used, which is one
great advantage of this method. Secondly, unless the piece of
tissue is thin, it does not adapt itself properly to the concave
floor of the embedding mould.

During the process of embedding it is necessary to hold down
the slice of tissue with hot needles until the paraffin has set
sufficiently to hold it in its curved position on the floor of the
mould. While the paraffin is cooling, the mould must of
course stand on a horizontal surface.

The paraffin block thus obtained must be detached from the
mould and fixed truly on the rocking-arm, in a position exactly
corresponding to that of the pattern-block from which the
mould was made. The razor will at once commence to cut

complete sections of the curved surface of the block.

The method is much simpler than it sounds in description,
and when once the plaster mould is made, takes no more time
than {embedding on a flat surface. In this way I have
obtained uniplanar sections from blocks 1}-inch in diameter
without difficulty.

I cannot conclude without expressing my belief that the

292 OBTAINING UNIPLANAR SECTIONS WITH ROCKING MICROTOME.

habitual use of sections of large area, in which the naked-eye
relations of the parts could be easily traced, would be of great
advantage in pathology. With the small sections at present
generally used, the view of the pathological condition obtained
may be compared to that of the interior of the bladder given
by a single endoscopic field. The same thing is probably true
in normal histology.

ARCHAZOLOGIA ANATOMICA.
IX.
HILUM.

HiLuM is a good and ancient classical word. It is given by
Pompeius Festus (de Significatione verborum, ed. Gothofried,
p. 296), with the definition putant esse quod grano fabae adhaeret,
ex quo nihil et nihilum. As this work is for the most part an
abbreviation of the oldest Latin vocabulary, that of Verrius
Flaccus, who lived in the Golden Age, about the beginning of
the Christian era, this gives the word a respectable antiquity.
From the insignificance of the bean seed-stalk it came to signify
metaphorically anything very small, so that a fourth century
lexicographer, Nonius Marcellus, defines it in his work, de
Compendiosa Doctrina, ii. 121, as “breve quoddam.” It had
got this sense in the oldest Latin writers; thus Ennius writes
in his Annales:
terraque corpus
quae dedit ipsa cagit, neque dispendi facit hilwm.

In lke manner Lucilius the satirist, writing more than a
century B.C., says, quod tua laudes culpes non proficis hilum
(xxx. 33); and in xiv., hilo non rectius vivas.

The author who uses the word most frequently is Lucretius.
He employs it in the sense of a minute particle or amount, like
our old English word whit. Speaking (iii. 220) of the soul as
consisting of very small seeds, so inwoven in the body that its
withdrawal does not alter the corporeal weight, he says:

incolumem praestat nec defit ponderis hilum.

Again, when speaking of changes of mind, he predicates that
they necessarily require the addition of a new part, the re-
arrangement of components or the subtraction of a hilum
(iii. 514), but the Immortal wills not such a withdrawal,

nec tribui vult
immortale quod est quicquam neque defluere hilum.

294 ARCHAOLOGIA ANATOMICA.

In iv. 515 he describes the mischief done to a building by the
use of an incorrect measuring rod, si ex parti claudicat hilum.
So:also, iv. 379, nec tamen hie oculos falli concedimus hilum,
“nevertheless we do not admit the eyes to be deceived a jot.”
In iii. 783 and v. 1408, neque inter se contendant viribus hilum,
and neque hilo, the word is construed with the negative
particle, as it is by the unknown poet quoted by Cicero (7'use.
Disp., i. v. 10),
Sisyphw’ versat
saxum sudans nitento neque proficit hilum.

Another ancient Latin author who employs the word in various
senses is Varro, who gives it as the name of a small kind of
sausage (v. 111). Jn quo quod tenwissimum intestinum jartwm
ila ab hilo dicta. Later on he describes another kind, probably
made in the same narrow part of the gut, which he calls Longavam
quod longius quam duo hila. As if to emphasise that this sausage
is so called from its size, he quotes the passage from Ennius
above given. Farther on (113) he uses the word in the sense
of something small when speaking of filum, Filwm quod minimum
est hilum; id enim minimum est in vestimento. This sense he
also expresses in speaking of its negative derivatives, ni/il and
athilum (ix. 54 and x.81). In Stephanus’ Thesaurus, s.v. Hilum,
the author says, Varro tamen de L.L. 4, Hilum swgnificare censwit
Medullam ejus ferulae quae Asphodelus vocatur, but 1 cannot find
the passage referred to.

Charisius, in his Ars Grammatica (ed. Putsch, i. p. 79), sup-
poses that Varro confounded Ailwm with another word hilla,
but it is plain that he specially quotes Ennius to show the
sense in which the word was used. Hilla, according to Pliny,
xi. 79, is the intestine, a word not given by the oldest lexico-
graphers, but which was used in the sense of sausage in the
familiar lines of Horace (Satire ii. 4. 60):

Perna magis et magis hillis
Jlagitat immorsus refici.

The commentator Acron remarks that the hille are ‘éilin
intestina hirci (ed. Havthal, ii. 288). Macrobius (Somn. Serpion.
vi. 77) says that hilla is a diminutive from Aira, the large
intestine; see Plautus (Curculio, ii, 1. 23).

Plautus also uses hillae in the sense of sausages when he

ARCHAOLOGIA ANATOMICA. 295

speaks of hilias infumatas et swumen. See also the line from the
mmenranns of Decius Laberius :

adolescenie nostro caedis hillas.

And another from an unnamed poem by the same author:
lambum item
hillam cocwm si lumbum adusset.

In Ausonius Popma’s de Differentiis verborum, s.v. nihil, he says,
est autem hilum proprie medius volae serobieulus.

- The foregoing study of the word is enough to show that
hilum is a good classical Latin word, and throughout the whole
range of ancient and medieval literature there is no such word
‘as hilus.

As an English word, hilum was used in the sense of a small
amount in Daniel Pell’s curious work, “IIeAaros; or, an Im-
provement of the Sea,” upon the nine nautical psalms, published
ain 1659. He speaks of “unhewn sailors, that have no more
than a hilum of goodness in them.”

_ The first use of the word as a scientific term known to me is
in Linnzus’ Philosophia Botanica, 1751, p.'71. Here it is used
as the name for the spot of attachment of the seed, somewhat
in the original sense given by Festus. I cannot find any earlier
use of the name; it was apparently not in use in Bradley’s time
(1728), and egiiae (i. exiii) attributes. it to Linnzus, and
prefers it to the Malpighian term fenestra. In this sense the
word is familiar to botanists, who almost always use the Linnean
form hilum (but I note that in German de St Pierre, 1870, the

alternatives hilum, hilus, hylum, hylus are all given).

i
.

It is easy to trace the stages by which the word became

‘applied to the area of attachment of the kidney. Eustachius

(Opuse. Anat., Venet., 1564, p. 31) compares this organ as to its

‘Shape with the Fascolos or kidney-bean ; and when describing its
“margins he says, interius vero, qua vena et arteria in eos inseritur’,

‘simi & natura facti sunt et in eam retusae lineae speciem curvati,
quae treicijs arcubus non inepti comparari potest: Galen had,

before this, called the hilum of the kidney ra cya; other authors
called it in later times concavité (Winslow), sinwosité (Portal),
porta renis (Fallopius), etc.

The Eustachian description is adopted and somewhat para-

phrased by Haller (1765, xxvi. § 1. 4), who says, Homini renis

296 ARCHAOLOGIA ANATOMICA.

Jigura est, quae phaseoli, ut nempe facies anterior et posterior com~
pressa sit, et utroque hince per aciem convexam semielipticam
uniatur, inde per hilum quo interior longitudo renis exsculpitur.

Here he is, as far as I know, the first to apply the Linnean
name to this bean spot on the bean-like kidney. In the sentence
just quoted the word is accusative, but in continuing the
Eustachian description he makes its nominative hilus, Hilus
recte cum arcus T'urcici. Later describers have used the samé
comparison : thus Cruveilhier has “ La figure du rein ne saurait
étre mieux comparée qu’d celle d'un haricot dont le hile
serait en dedans.”

That the use of the Linnean name was suggested by the
bean simile is confirmed by the fact of this word being used by
Haller of the kidney only, not of the spleen or liver. The
transverse fissure of the latter-is with him the porte. He uses.
Galen’s plural, that author having described the ports as two
(de Formatione Fetu, iii), and Haller speaks accordingly of the
vena portarum.

Once started, the error was propagated by Meckel, and it is to
be found also in the works of Lauth, Krause, Henle, and
Sémmerring. Hyrtl, in his Onomatographia, recognises that
hilum is the proper word, but he has not the courage of his.
conviction, and uses hilus in his Topographical Anatomy. The
French authors, as they appropriate and gallicise the word hile,
are saved from the necessity of choice between the two.
English writers for the most part use the Linnean hilum. It is.
so in Knox, Wilson, Heath, Morris, Gray, and in Todd’s
Cyclopeedia, as well as in Ellis (pace Murray’s Dictionary, s.v.).
Quain is impartial, using Ailus in the 1882 edition, and Ailwm in
that of 1896. Cleland also follows the Germans.

Reviewing the history of the word, there cannot be the shadow —
of a doubt that Linnzus was correct in the form, if not in the
usage, of the word, and that the mistake in gender was a slip of
Haller’s; quandogue bonus dormitat Homerus. Had he meant
to make a new word he would have said so, and explained his.
intentional departure from the acknowledged form. Whether,
as the hilum of the kidney is not exactly the same as the hilum
of the bean, there is need for a new word is a debateable point;
but until this is definitely agreed to, and hilus put on the same

ARCHAOLOGIA ANATOMICA. 297

etymologically as Paracelsus’ word gas, frankly, as a
arism, those who are interested in the maintenance of some
ree B, a classical purity in the nomenclature will do well to
to the atin of the word that is sanctioned by the usage
y-three centuries. _
an the place to discuss its etymology; but in view of
ions of / and f in early Latin words, it may be that
8 hit on a correct parallelism, and that it is a variant of

an. Compare irewe and ire hedus and fedus, hordewm

ie KE

THIRTEENTH REPORT ON RECENT TERATOLOGICAL
LITERATURE. By Berrram C. A. Winpie, M.D., Se.D.,
F.R.S., Professor of Anatomy in the University of Birmingham,

[The author of this report will feel greatly obliged if writers on teratological
subjects will supply him with reprints of their papers for use in the preparation
of further reports. ]

I. GENERAL.

Iy an address by Scuarz (i.), of which a summary has appeared in
the British Medical Journal, the question has once more been raised
as to: how far Mythology is indebted to Teratology for some of its
figures. This matter has previously been dealt with by Berger de
Xivrey in his Traditions Tératologiques, by Bland Sutton and by
Ballantyne. Schatz identifies the siren with the sympodial foetus,
the centaur with the foetus with four lower extremities, the gorgon
head with an acormic placental parasite, Janus with the janiceps
fostus, and so on. The speculation is one of considerable interest.
RaBavp (ii.), in a lengthy paper dealing with experimental determinism
and the individuality of the germ, says that, judging by many of the
results obtained by experimenters, one would be tempted to believe
that the fundamental principle on which all experimental science
depends is not applicable to teratogeny. In fact, it would seem as if
the artificial production of abnormal embryos was subject to no law,
the same teratological types being produced by the most varied
causes. After stating this difficulty, the writer proceeds to examine
the classes of experiments which have been entered upon, and
particularly those which have been carried out upon hens’ eggs, which
—as he very aptly points out—are not really ova but multicellular
organisms at the time when experiments are made upon them, a fact
which must always be borne in mind when estimating the evidence
derived from this quarter. He concludes that the artificial production
of monstrosities is bound up with a strict and precise determinism
which experimenters must master, though as yet they have not done
so, The greatest difficulty, he adds, will not be to lay down the
rules of determinism, so much as to connect the experimental facts
with the spontaneous, and above all with those met with amongst
the mammalia, and particularly in man. Rasavp (iii.), in another
paper, deals with the relationship between the pathological and terato-
logical states, and points out that in considering the production of
congenital conditions, one must not merely take into account the
factor concerned in producing the disturbance. The embryonic
organism does not necessarily react in the same way as the adult
organism, and its reactions depend as much on the intensity of an
agent as upon its specific character. There are two categories of
congenital states strongly opposed to one another, and carefully to be

| “io a
a? P ‘ ———
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i
_
2

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THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE. 299

distinguished. These two states may be the result of the same or
different agents, capable or not capable of producing in the adult a
pathological alteration. They are on the one hand abnormalities, and
on the other maladies. There is also a third category, in which
abnormality and malady are mixed up with one another. THomson
(iv.) points out, in a paper on Defective Co-ordination in Utero, that
there are at least three types of congenital malformation of hollow
viscera, in which the main anatomical abnormality present consists in
very great muscular hypertrophy, for which no permanent organic
cause is discoverable. These are, (a) Congenital hypertrophy of the
bladder, with dilatation of the ureters and renal pelves, and with no
organic obstruction. () Congenital hypertrophy of the colon, with
no organic stricture. (c) Congenital hypertrophy of the pylorus and
stomach wall. The writer seeks to explain these conditions by
attributing them to a functional cause, viz., a disturbance of the
normal co-ordination. Rapaup (v.) has made a long and critical
study of the question of the feratological nature of malignant tumours.
Without denying the possibility that an arrest of development may
become the origin of a tumour, he thinks that such a phenomenon is
probably rare, since its occurrence is surrounded by so many diffi-
culties. In any case, for such a group of elements to develop into a
malignant tumour, the intervention of an external agency is necessary.
But if this agent can produce the same effect upon any group of adult
cells, it is difficult to see why the theory of retained embryonic
elements is required. But in some cases it does seem as if, by a
simple process of excessive growth, an embryonic inclusion may
develop into a tumour, in this case a truly congenital tumour.
SELIGMANN (vi.) has contributed a paper dealing with Albinism
amongst Melanesians and Polynesians, in which he shows that in this
part of the world as elsewhere the condition is hereditary. Partial
albinism occurs, but more rarely than the complete form. The
subject of Fatal Bone Disease was dealt with at the annual meeting
of the British Medical Association during the last year in a discussion
opened by BatiantyNe (vii.), for an account of which the inquirer
must be referred to the Journal of the Association. ReGNauct (viii.)
gives a few notes on achondroplasia, in connection with the cases of
two subjects with asymmetry of the pelvis. The antero-posterior
measurement was diminished. In the lower extremity the legs were
relatively shorter than the thighs. BrLaNnoarp (ix.) discusses the réle
of the amnion in the production of abnormalities, a part which he
believes that it undoubtedly plays. It may act by compression, by
the formation of adhesions, or by the production of constricting bands.
Compression leads chiefly to deformities, irregularities, and displace-
ments of external parts. Adhesions are preceded by rubbing; in-
flammation follows, and the production of cicatricial tissue. Traction
may also be exerted, and deformity added to destruction. The part
played by bands is that of strangling and sectionising portions of the
body. Bavumearr (x.) describes a case of vesicular mole accompanied
by ovarian cysts, and states that he believes there is a connection of

- eause and effect between the two, though at present no scientific

300 PROFESSOR BERTRAM C. A. WINDLE.

explanation of the relationship is forthcoming. GaLuanr (xi.)
describes a mast remarkable case of ha/f-embryo, which he states to
be unique (the present reporter believes that he is right in this).
The whole right side of the trunk was absent, and the remainder was
so curved that the left lower extremity occupied the position of the
right upper with respect to the head. Perhaps this will be better
understood if it is stated that the figure appears to represent a foetus
with the entire of the body below the pectoral region removed. The
single foot was provided with seven toes. The head was anencephalic.
‘It is unfortunate that no account is given of any dissection of this
very remarkable specimen. Cooke (xii.) adds another to the cases of
complete transposition of the viscera. Rasaup (xiii.) contributes a
very lengthy and important monograph on the subject of cyclocephaly.
The embryology of the condition is fully worked out, and the paper
is illustrated by numerous figures. This is a most valuable con-
tribution to the subject, but unfortunately not of a kind which can
be easily abstracted. But it must be read by every person working
at this particular corner of teratology. Tarurri (xiv.), in three large
monographs, .has dealt with the subject of Hermaphroditism, on the
lines made familiar by his monumental Storia della Teratologia.
The classification which he adopts is as follows :—

ANATOMICAL _HERMAPHRODITISM—

I. Specific Hermaphroditism of the sex-glands. (True
Hermaphroditism. )
A. True Bilateral. A testis and ovary on each side.
B. True Unilateral. On one side a testis or an ovary,
and on the other both.
C. True Lateral (Alternate). A testis on one side and
an ovary on the other.
II. Aplastic Hermaphroditism of the sex-glands. (Atrophic or
Neuter Hermaphroditism. )
III. Pseudo- Hermaphroditism.
A. Male.
(a) Persistent Mullerian duct.
(6) Feminine external appearance,
B. Female.
Persistent Wolffian duct.

CuINICcCAL HERMAPHRODITISM —

I. External Pseudo-Hermaphroditism.
A. Tn man: Ectopia vesice.
Perineo-Scrotal Hypospadias.
Gynecomastia.
Feminism.
B. In female.
II. Heterotopic Pseudo-Hermaphroditism (Taruffi).
Ill. Psychic Hermaphroditism (Krafft-Ebbing).
IV. Sexus Incertus.

3

aw

THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE. 301

Kraspet (xv.) records the case of a supposed male, a teacher in a
school, short, but with a moustache and beard. There was a distinct
penis, with extreme hypospadias, no scrotum nor testicles. There
were well-formed labia, and under chloroform a small vagina and
cervix were detected. An operation having been performed for an
abdominal tumour, this proved to be a cystic ovary. There was a
small uterus, broad ligament, ete. Another case of Hermaphroditism,
in which the diagnosis of sex was made. post-mortem, is recorded
by Westerman (xvi.).. The patient was aged 30. The penis was
eae long. The urethra opened into the perineum, whilst along

under surface of the penis ran a groove. . From each side of the
penis proceeded a cutaneous fold. The two surrounded the urethral
meatus and a small opening behind it, and united to form a posterior
commissure. The second opening was small, and led to a canal which
ran in the posterior wall of the bladder ; there was an indication of a
hymen. The hair was thick on the pubes and anus, and covered the
inner side of the rudimentary labia, which did not contain testes. A
left Fallopian tube, 2} ins. long, ran outwards from the posterior wall
of the bladder, with distinct fimbriz, round ligament, and mesosalpinx.
There was a slight thickening of the tissues at the site of the ovary.
The thickened tissue contained no epithelium, follicles, or Pfiuger’s
tubes. Only when the peritoneum was dissected off the back of the
bladder was the uterus (under 2 ins. long) and the vagina (3 ins.)
detected ; the latter was pervious for an inch or so at the abdominal
end. In the right inguinal canal lay an open processus vaginalis,
which contained a bean-shaped organ. On further examination that
organ was found to be invested with a tunica albuginea. It contained
a quantity of well-formed tubules, and a trace of epididymis was
detected in the mesosalpinx. The tubules contained no spermatozoa.
The patient was clearly a male. Roger (xvii.) adds a further case of
Hermaphroditism. The subject was supposed to be a boy of 19.
The externa] genitalia were like those of a male, save for the pubic
hair, which conformed to the female type. There was a small vagina

- internally, with a normal uterus connected with it. On the right side

was an ovary, on the left neither ovary nor testis. Hamay (xviii.)
records a case of gynxcomastia occurring in anegro. WI.LIAMS (xix.)
has compiled a valuable list of cases of precocious serual development
in a paper dealing with this subject. In some instances menstruation
commenced immediately after birth. Harrison (xx.) has a paper,
with illustrations, dealing with a tailed baby. The appendage was
removed at the age of six months, and then measured 7 cm. It was
only 4°4 cm. at birth, so was growing fairly rapidly. It was capable
of contraction. A microscopic examination was made after its
removal. The skin and its appendages were normal. Internally
there were blood-vessels, nerves and striated muscular tissue (a few
bundles), There was no trace of anything like a medullary cord or
of notochordal tissue. DrnrKer (xxi.) calls attention to the observa-
tion made by Balez in 1873 of the pigmentary patches of the sacro-
lumbar region of Japanese. The patches are blue or grey, and are
said to be present in all Japanese babies. They appear about the
VOL. XXXVII. (N.S. VOL. XVII.) —APRIL 1903. 21

302 PROFESSOR BERTRAM C. A. WINDLE.

fifth month of intrauterine existence, and generally disappear
between the second and the fourteenth year, but may persist all the
life. Later, Hansen has called attention to similar patches on new-
born Esquimaux children. Matignon has observed the same thing in
China, and v. Bulow in Samoa. Curore (xxii.) has a very elaborate
monograph on the skeleton of an anencephalus. Katz (xxiii.)
describes a symelian fatus, also the subject of anencephalus. There
were no kidneys, bladder, ureters or urethra. Testicles were present
but no penis. The great intestine ended at the promontory of the
sacrum. All bones of both lower extremities were present, a some-
what unusual condition. SzawLowski (xxiv.) records the following
rare abnormalities in connection with the vertebral column: (1) a
rudimentary rib, articulating with the fourth cervical vertebra ; (2)
a transverse foramen in the fifth lumbar and first sacral vertebrae ;
(3) a process from the ventral surface of a coccygeal vertebra.
Dwicur (xxv.) also records a case of a transverse foramen in a fifth
lumbar vertebra. He is of opinion, however, that this was a twenty-
fifth vertebra, whilst the last-named author’s was a twenty-fourth.

II. Dupticity, Etc.

WALLA (xxvi.) records a case of wnioval triplets, male, with common
placenta and chorion and three separate amniotic cavities. A stilh
more abundant output comes from Japan in the case described by
Sato (xxvii.) where a woman aged 37, who had previously had eight
labours, gave birth to five children at her ninth pregnancy. The first,
third, and fifth of these were male, the rest female. A paternal
cousin and her daughter had both been the mother of twins, but
there was no other evidence of heredity in multiple bearing. Licn»em
(xxviii.) records two cases of fatus papyraceus. In the first there
was a history of heredity in twinning, but not in the second. In the
first the placente were separate, in the second there was a common
placenta and the insertion of the cord of the imperfect foetus was
velamentous. A further case of the same kind is recorded by Sonn-
BERG (xxix.), remarkable for the small size of the fetus papyraceu,
which measured only about two-thirds of an inch. The case of the
conjoined twins Radica-Doodica having already been mentioned in
these reports, attention may now be called to the fact that they were
separated from one another during the year by surgical means. An
account of the operation, with notices of other similar cases, will be
found in the British Medical Journal (xxx.), wherein are also notes
on early instances of adult duplicities, the Biddenden Maids (xxxi.)
and the Zwin Sisters of Fosscote and Scottish Brothers (xxxii.).
Luspre and Foreror (xxxiii.) record an instance of the birth of an
acephalus with a normal calf. It consisted of a malformed head,
with obvious lower jaw and a portion of intestine. There were
rudiments of brain and spinal cord. A case of fatus included in
the Ascending Meso-Colon is narrated by AHRENS (xxxiv.). The
tumour taken from a girl of seventeen was as big as a man’s head, and

ee eee

‘THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE, 303°

held nearly seven pints of a thick brown fluid. Its walls contained
all the component parts of the stomach, and its epithelium corre-
sponding net merely to that of the viscus just named, but also to the
mouth, cesophagus, bronchi and trachea ; so that the girl was provided
with a second alimentary canal, or at least a large part thereof, quite
unconnected with the normal passage. Poprscur (xxxv.) describes a
teratoma growing from the sacral region of a foetus, which tumour
was twice the size of a foetal head, and much impeded the course of
delivery. Jounson (xxxvi.) gives an interesting account of axial
bifurcation in snakes. Thirteen two-headed snakes are described by
means of skiagraphs, and the cases of others are mentioned. The
abnormality seems to be more common in some species than in others,
and the point of bifurcation is more likely to occur in the cephalic
half of the snake, and between six and thirteen per cent. of the entire
length from the cephalic end. The point of bifurcation of the verte-
bral column is a good deal more posterior than would be supposed
from an extvrnal examination. The skulls frequently appear united
externally when in reality they are not so. No specimen of posterior
duplicity has been described, though three of antero-posterior are
recorded, { Note.—In this respect the conditions resemble those found
in fishes.] LesBre (xxxvii.) publishes a series of observations on
_ pygomelia as observed in: two cows, a cock and a duck, the latter
looking as if it actually walked on four legs. An attempt is made at
_ the classification of different forms of the malformation, various
names having heen assigned according to the point of attachment of
_ the appended limbs. The writer thinks that all may be reduced to
the single condition of posterior duplicity, which he proposes to call
pelvadelphy. AntHony and SaLmon (xxxviii.) consider pygomelia to
_ be a double monstrosity, symmetrical and lambdoidal, of the syn-
_ cephalous variety. This view is based on the following proofs :---(a)
_ The presence above the point of confusion of the axes of double
_ abdominal organs, showing the double nature of the subject. (+) The
_ peculiar orientation of the supplementary limbs, which do not pair
_ with one another, but with the external limbs. (c) The presence
between each external limb and the adjacent internal limb of a
_ cloacal orifice. (d) The insensible transition which exists between
_ the most reduced pygomele and a janiceps. There are, however,
_ pygomeles of a parasitic origin, without double abdominal viscera.
_ Consequently, the writers think that the term ‘pygomelia’ should be
_ dropped, and that of ‘pelvadelphus’ substituted in the case of
_ pygomeles of the syncephalous group. ALLAN (xxxix.) has described

- a human pygmele aged 14. He has a third leg attached to the
- back and sides of the pelvis, on which he can support himself.

: 4 Anteriorly there is a normal penis with scrotum, and posteriorly a

second penis with cleft scrotum, containing two well-developed
testicles. {ihere is one anal aperture. A metatarsal bone and three
3 orgy are connected by cartilage with the femur of the accessory
Rawaup (xl.) deals with a case of sternopagous chick and with
the condition of monomphalism in general. _ The specimen was found
~ in an egg of four days’ incubation, though the individuals were

304 PROFESSOR BERTRAM C. A. WINDLE.

actually somewhat behind the development normal for that period. —

The heart condition is interesting, for that organ only receives two

vessels inferiorly, one from the embryo of the right, the other from —
its fellow. These are obviously the two omphalo-mesaraic veins.

The condition is not due to the fusion of four trunks. The fact is
that there is only one circulatory system for the two united embryos,

and this cannot be said to have arisen by the fusion of two stems, ©

There is no trace of any such thing even in this very early embryo,
in which there never has been anything but a single cardio-vascular
apparatus for the two individuals. ‘Turning to more general conclu-
sions, the writer deals with the fusions which, as Lereboullet has
shown, may take place in fishes. These fusions are not the cause of
the duplicity, but, on the contrary, its consequence. ‘The duplicity
itself proceeds neither from a coalescence nor from a fusion, To put

the matter briefly, the genesis of a double form is single; the two .

components form a whole from the commencement; it is one and the
same organism, having its own methods of development. The two
nervous axes are independent one of the other in these cases (sterno-
pagi), but as they both exist on a common embryonic area, the embryos
of which they represent the anlagen find themselves obliged to
develop at the expense of regions common to both, so that they must
have certain organs in common, wholly or partially, by necessity, and
without any phenomenon of fusion. From this community of develop-
ment result certain special processes. The double malformation con-

stitutes a single organism in two parts, each closely connected with —

the other, developing in concert under conditions rendered inevitable

by the duplicity. Pressure may afterwards cause secondary fusions,

but these unions are the consequence, not the cause of the duplicity.
RaBaup (xli.) gives the details of an instance of fission in the

embryo of a chick, confined to the spinal cord and muscle-plate.

The posterior limbs were not affected by the duplicity, there being
only two. Scumrrv (xlii.) has a paper on the gastrulation of double
trout embryos, with special reference to the concrescence theory. He
concludes :—(1) That the germinal areze which give rise to double
embryos are no larger and contain no more material than the normal.
The invagination of the entoblast begins on them simultaneously in
two places, and the lateral lip of one blastopore unites with that of
the other in a symmetrical plane. (2) The embryonic anlagen grow
slowly forward over the yolk, whilst the segments of the equatorial
ring grow the more rapidly the further they are from the embryonic

anlagen. (3) The material of the equatorial ring, from the commence-_

ment of embryonic development, passes into the embryo, which
elongates backwards. ‘There it is mainly utilised for the formation of
mesoblast. (4) The very marked flattening of the cells of the vitel-
line membrane causes a displacement of the embryos in a direction
from the originally animal to the. originally vegetable pole of the egg.

(5) The position of the first embryonic anlagen determines in all cases ~

the later arrangement of the double formation. The nearer the
anlagen were originally to one another, the sooner the embryos come
in contact with one another. (6) Each embryo grows as a separate

{

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a

THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE. 305

‘entity, but the opposed sides, and especially the mesoblast between,
have a less free development than the outer edges. (7) The concres-

_ eence theory cannot by itself explain any kind of double embryo.

Bromann (xliii.) has a most suggestive and admirably illustrated

‘paper on atypical spermatozoa, which he divides into four groups :—

‘A. Differing from the normal only in size—giant and dwarf sper-
matozoa. B. Possessing a single head but two or more. tails. C.
Possessing two or three heads, with either a single or a multiple
tail. D. Single and of normal size, but presenting some abnormality
of shape. In the latter portion of the paper the question of the

relation of these abnormal spermatozoa to the origin of. homologous

twins is discussed.
Ill. Heap AND NECK.

HausHavrer and Brigust (xiliv.) give an account of a case of
meningo-encephalocele projecting as a hernial structure from the left
frontal eminence of a new-born child. Besides the tumour there was
very serious malformation of the face, all that portion of which be-

tween the lower jaw and lip (both of which were well-formed) and

the forehead formed a single cavity with irregular margins. Norsa

'(xlv.) deseribes two cases of congenital encephalocele affecting white

mice. The region affected was partly the vault and partly the
occipital portion of the skull. A case of porencephaly is fully
described by Sutrres (xlvi.). The right hemisphere of the brain was
-well-convoluted and normal. On the left side the convolutions of

_the mesial and orbital aspects seemed to be intact, if poorly developed.

The whole region of the fissure of Sylvius was occupied by a cavity,
the remains of a cyst which did not establish any connection with
the ventricles, but was lined by a thickened membranous layer of pia
mater in which could be recognised scattered areas or flakes of grey
matter. The left middle cerebral artery narrowed rapidly after giving
off the anterior perforating branches, and could be traced to its
further distribution only as a thread. The writer thinks that the
lesions in the artery had occurred in the later months of foetal life,
and was due to rupture of vessels in the placenta. The minute
anatomy of the stem portion of the brain and of the spinal cord is
detailed with considerable minuteness, and illustrated by many figures.
Warrineton and Monsarrart (xlvii.) describe certain defects of the
central nervous system in a child aged 8 weeks, the subject of a
healed lumbar spina bifida. The cerebellum was represented only by
a few folia, the remainder with the peduncles being absent, No
myelinated fibres entered it, and the transverse fibres of the pons and
nuclei pontis were absent. The restiform body was hardly represented,
the olives were entirely absent, as also were the external arcuate fibres,
the superior cerebellar peduncles, the grey nuclei of the cerebellum,
and the nuclei rubres tegmenti. The cord was symmetrically divided
by an exostosis in the dorsal region into two parts. Medullated
fibres were entirely absent from its lower portion ; in the upper part

_ they were only found in Burdach’s column and in the anterior ground

306 PROFESSOR BERTRAM C. A. WINDLE.

substance. Regnaur (xlviii.) describes a case of a woman with two
noses. The left had two nostrils and so had the right, but on this
side the internal nostril was rudimentary. The writer positively
puts forward the ridiculous explanation that the condition is the
result of the fusion of two embryos, of each of which only one-half
remains. Lon@o (xlix.) narrates a case of divided nose in a child of
8 months. The left side was normal, but the right was a trumpet-
shaped structure, the narrowest part of which was inserted between
the inner canthus of the eye and the root of the nose. At the
extremity of this tube was a small aperture through which air passed.
Wynter (1.) has recorded a case of absence of nose and anterior nares
in a child et. 6 weeks. There was no hare-lip or deficiency of the
premaxilla. The hard palate was drawn up so as to simulate cleft
palate, the soft palate was perfect. Warsow (li.) records and figures
a case of cleft palate, hare-lip, and cleft nose in a child aged 3
months. Hany (lii.) records a somewhat similar case in an adult
Chinese male. The face was normal on the right side, on the left
the entire of the internal incisive portion was wanting. BrogckaERT
(liii.) adds some further cases to the examples of congenital perfora-
tions of the soft palate which he had-already published in Charles
Bambeke’s Livre Jubilaire, as recorded in an earlier report of this
series. ‘lhe instance here given is one of asymmetrical perforation of
the posterior pillar of the fauces. A case of branchiul cleft persisting
may be noted from the British Medical Journal (liv.). Brapuxy (lv.)
records two cases of abnormality in the dentition of ruminants. (a)
Skull of a horse (lower jaw absent), seven cheek teeth on each side,
a case of multiplication of serial organs. (b) Skull of anencephalous
calf. The fronto-nasal process bore teeth with some resemblance to
those of a camel. This may have been a reversion to an ancestor
provided with a fuller complement of teeth than is present in the
modern Bovide. Grurrrima-Rueereri (lvi.) notes an instance of
great reduction in size of the ala of the sphenoid in a Melanesian
skull, an atrophic condition which was correlated with a marked
antero-posterior enlargement of the squamous portion of the temporal
bone. Brpone (lvii.) describes a pedunculated appendage, fibro-
muscular in character, which was found growing from the chin of a
new-born child. Rowrer (lviii.), in a note on the relation between
the formation of the auricle of anthropoid apes and certain congenital
malformations of the human auricle, says that he has observed,
amongst other anomalies, a cartilaginous strip passing from the crus
helicis ascendens through the cymba in a rectangular direction to the
point of bifurcation of the truncus antihelicis, which took origin on
the upper side of the tragus on the incisura supratragica. This he

believes to correspond to the crus anthelicis anterior described by —

Schwalbe in the ears of monkeys.

IV. THORAX,

Herrz (lix.) describes a case of congenital dilatation of the aorta,
which possessed four sigmoid valves, but only one coronary artery.

THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE. 307

This vessel sprang from the interval between two of the valves and
divided subsequently. Karz (Ix.) records a case of extreme con-
traction of the aorta immediately beyond the point at which the left
subclavian artery is given off. Here it became so small in calibre
that it was only just possible to insert a probe into it. The contracted
portion was about | cm. in length, and opened into the ductus
arteriosus, which was of considerable size. There was also a per-
sistent foramen ovale. The child thus affected lived for three days.
Bouruor (lxi.) describes a heart in which there was a complete
absence of any connection between the pulmonary artery and the right
ventricle. At the point of its bifurcation the vessel was of normal
size, but below this it became rapidly narrower and completely dis-
appeared above the ventricle. Accompanying this condition were
persistent foramen ovale, an aperture in the septum ventriculorum at
the undefended spot, and persistent pervious ductus arteriosus. The
right ventricle was much decreased in size. The child thus affected
lived for three days. Brapuery (Ixii.) records a case of a left superior
(anterior) vena cava which he observed in a dog. Daser (lxiii.) notes
an anomaly of the left vena innominata, this vessel passing, to join
the superior vena cava, behind the ascending aorta and in front of
the right pulmonary artery. De Veccut (lxiv.) describes a rare form
of chorda tendinea which ran from one of the cusps of the mitral valve
to the wall of the ventricle near the aortic orifice. According to the
author, only three similar cases have been recorded.

VY. ABDOMEN.

ZANDER (Ixv.) is the author of a case of anus vestibularis in a
female «xt. 20. Between the nymph were three openings—the
meatus urinarius, which was normal, the introitus vaginee, somewhat
narrow, and, one-fifth of an inch further back, the opening of the
intestine. This was surrounded by wart-like elevations of mucous
membrane, and there was a distinct sphincter internus. A somewhat
similar case is recorded by v. BARDELEBEN (Ixvi.). M‘Arruur (Ixvii.)
records a case of imperforate anus in which the rectal cloaca opened
into the bladder. There was also external hermaphroditism.
Durante (Ixviii.) gives details of six cases of congenital obstruction of
the intestines. Of these two were due to torsion, but in the remainder
there were congenital defects. In two there was occlusion of the
duodenum just below the place of entry of the bile and pancreatic
ducts. In two there was occlusion of the small intestine, and in both
of these cases the upper part of the gut formed a distended loop
which lay in the left iliac fossa, the remainder being a thin cord.
The author thinks that the theory which best explains the condition
is that of the failure of the artery to the portion of intestine affected,
the failure arising from contraction or obliteration of the vessel during
intrauterine life. Dusarrer (Ixix.) describes a case of Merckelian

308 PROFESSOR BERTRAM C, A. WINDLE,

diverticulum, where an artery from the superior mesenteric passed
from the diverticulum to the parietal peritoneum, forming a band
about 2°5 cm. long. The remarkable thing was that this artery was
not contained in a mesentery, and the author thinks that its peritoneal
clothing must have disappeared in the course of growth. ALrucHOFF
(Ixx.) gives an account of an instance of unusually long vermiform
appendix. The tube first passed upwards behind the cecum, this
part’ measuring 15°0 cm. in length. Then it bent to the left
and downwards, and lay in the mesentery of the small intestine.
This latter portion measured 10:0 cm. in length, and terminated. in a
bundle of fibrous tissue, well defined, which was 4:0 em. in length.
The appendix was 6 mm. in thickness. Duranre (1xxi.) describes a
case of congenital adeno-myoma of the intestine. There seems to be
some possibility that this may have been an atrophic intestinal
diverticulum. In the same subject there was also a supernumerary
lobe to the liver about the size of a nut, and situated on the anterior
aspect of the right lobe. Janicor (Ixxii.) gives an instance of horse-
shoe kidney, which seemed to be made up of three renal elements,
and occurred in a case of hydramnion. Francors-DanviniE (1xxiii.)
narrates two cases of congenital anomuly of the kidney: (a) absence
of the organ on the right side; () small right kidney. Weighed
30 grms. as compared with 250, the weight of that of the left.
LOEWENHARD (lxxiv.) describes an ectopic right kidney, which received
arteries from the common and internal iliac arteries. The vein passed
to the left common iliac. Karz (lxxv.) describes a case of absence of
the penis, in which there were a number of other malformations.
There was no left kidney, and that of the right side presented the
condition of congenital hydronephrosis. The left vas deferens opened
into the right ureter, and there was no right vas deferens. The
intestine opened into the bladder, and the urethra ended in a
cul-de-sac below the symphysis pubis. There was a single umbilical
artery, and the limbs presented various malformations. STAVELEY
(Ixxvi.) gives a series of instances of almormalities of the uterus, met
by him in practice, and chiefly of clinical interest. Other cases of
uterine malformation which may be briefly mentioned are :—Warp
(Ixxvii.), wterus didelphys. Kostensko (Ixxviii.), uterus bicornis with |
twin pregnancy, one foetus in either horn. Krever (lxxix.), uterus
didelphys with atresia vagine, but with no other malformations.
Girvin and OstHermer (1xxx.), further cases of a similar character.
Of deficient development of the uterus the following cases may be
mentioned :—Grrop (Ixxxi.), uterus unicornis. The right horn was
present, the left was detached and connected with the uterus at
a point where the annexe are usually found. Haran, a case of
congenital absence of the uterus and the upper two-thirds of the
vagina. The ovaries were present and embedded in the broad
ligament.

THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE. 309

VI. ExtTREMITIES.

Wirtre.p (Iixxxiii.) consecrates an inaugural dissertation to the
subject of Sprengel’s deformity, viz., upward displacement of the
scapula of one side. [Note.—Further references to the literature
will be found in former reports of this series,—VIII. xlviii—X. Ixxxv. ]
A case of Ectromelus is detailed by M‘GiBpon (Ixxxiv.). The stumps
of the lower extremities ended in fleshy nodules, but those of the
upper were rounded as after amputation. Bones could be felt in all
the stumps. There was no family history of malformations.
Azow.ay (Ixxxv.), a case of Hemimelus. The right hand consisted of
a single finger, probably the index or medius, and there was apparently
no carpus. On the left hand there were three fingers—pollex, index
and medius. Consranvin-DaNIEL (Ixxxvi.), a case of bilateral absence
of the radius, complete on the right side, almost so on the left, with
the distortion of the hand usual in such cases. The thumb in each
hand was represented by a cutaneous appendage. Frre (lxxxvii.)
describes a case of bilateral absence of the sterno-costal portions -of
the pectoralis major. HatiLopran (Ixxxviii.) contributes the following
notes of his dissection of a case of conyenital dislocation of the hip-
joint in a girl et. 24 years. The head of the femur was pointed, and
owed this appearance to the flattening of its posterior aspect. The
ligamentum teres was much elongated. The neck of the femur was
short, and its angle nearly normal. As regards the innominate bone,
the acetabulum was more open than usual, higher up on the bone
and more posteriorly situated. Its articular surface was normal in
shape, but it was very small. The secondary articular cavity was
formed at the expense of the cotyloid ligament, whieh was enlarged
and excavated at its upper part. A dissection of a ease of the same
kind but of much older standing is recorded by Morestin (Ixxxix.).
The femoral neck is greatly reduced in size—in fact, can hardly be
said to exist—so that the mass, like an irregular mushroom, which
represents the head of the bone, is sessile. It is flattened, very hard
and smooth, but devoid of cartilage, and anteriorly more worn than at
the back. The cavity in which the head was lodged was a new
formation, developed on the external surface of the ilium by periosteal
ossification. The acetabulum was covered by fibrous tissue; it was
triangular at its upper part, and its posterior part was bent over the
anterior so as to hide the base of the cavity. There was no cartilage
in it, and no ligamentum teres. Borner (xc.) records a case of macro-
dactyly of the middle finger of the right hand. As the radiograph
well shows, this is not one of the ordinary cases where the increase in
size is due to the soft tissues, but is one of actual gigantism of the
bones. Morestin (xci.) narrates a case where there was a post-
minimus on both hands und both feet of the same person. Howsg
(xcii.) has made a study of the hexadactyle cat’s foot, taking into
consideration walking-pads, muscles, vascular and nervous: structures,
as well as the skeleton. Some facts suggest that the extra digit

310 PROFESSOR BERTRAM C. A. WINDLE.

occurs on the radial side, others point to the ulnar, but on the whole
the balance of evidence points to the existence of the extra digit on
the radial side of the three ulnar digits. Prirzner (xciii.) records a |
case of bilateral duplication of the fifth toe. The left metatarsal was
bifid, and each part carried a separate set of phalanges, two in the
external toe, three in the internal. The right metatarsal was broader
at its head than normal, but not bifid. It carried two sets of
phalanges identical with those of the opposite side. Monro (xciv.)
has a case of congenital deficiency of certain phalanges. In the fore-
fingers of both hands the second phalanges are absent. The proximal
phalanx is normal. The terminal phalanx has the expanded basal
portion longer and larger than usual. In the little finger, in the
joint between the first and third phalanges, on its outer side, a small
wedge-shaped bone is interposed, partially dividing the joint. This
wedge is probably the rudimentary secondary phalanx. The missing
bone of the forefinger in all probability forms part of the enlarged
base of the terminal phalanx. In the right foot the second phalanges
are all rudimentary, and differ in size and shape from the normal. In
the left foot the second phalanges are absent from the second and
third toes. A cousin on the paternal side is said to have had a very
short forefinger, but there is no other evidence of heredity. WALKER
(xcv.) gives the genealogical table of a case of malformation of the
hand, which extends over five generations. The malformation
consists in the absence of one or more bones of the little and ring
fingers, and absence of various joints between the phalanges, bony
anchylosis accounting for the latter deficiency, Karz (xevi.) records
the condition of syndactyly in a case where many other malformations
were present, perhaps the most interesting and important being com-
plete symblepharon in both eyes. There was also atresia ani,
divarication of the pubic bones, so no symphysis, and pes varus of
both sides. The child died immediately after birth. VoLKov (xevii.)
has a contribution to the literature of supernumerary bones of the foot—
and triphalangy. He especially refers to the os trigonum, external
tibial bone (z.e. detached scaphoid tubercle), secondary cuboid, double
first cuneiform, and intermetatarsal bone. He concludes, (a) The first
metatarsal (or first metacarpal) may be considered to be—as it was—
the first phalanx. (b) The first cuneiform (or the trapezium) may be
considered as the first metatarsal (or metacarpal) reduced. (c) The
tubercle of the scaphoid in man or the external tibial (or external
radial) in rodents may represent the vestige of the first cuneiform
(trapezium). (d) The bones known under the name of prehallux or
precuneiform are probably only the more or less transformed sesamoids
of the first metatarsal (first metacarpal), or of the first cuneiform
(trapezium) of the actual nomenclature. Dwieur (xcviii.) describes
three feet with accessory ossicles :—(a) Os intercuneiforme. This seems
to be described for the first time. It lies on the dorsum of the foot,
in a fossa between the proximal ends of the first and second cuneiform
bones. (b) Intercuneiforme and calcarius secundarius. (c) Para-
cuneiform, possibly a pathological structure. Lies at the base of the

THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE. 311

internal cuneiform, and between it and the scaphoid on the dorsum
In this case there was also a calcaneus secundarius.

_ Ravper (xcix.) notes a case in which on both sides of the body there
were present an os styloideum carpi and a supra-condylar hook on the
Raver (c.) also contributes a note on the os styloideum

of the foot.

humerus.

carpi ultimale, with an account of its internal structure.

REFERENCES.
Brit. Med. Journ.
Rev. de? Ecole d’ Anthrop. de Paris, Dec. 1901.
Bull. de la Soc. Philomathique de Paris, t. ix. p. 77.

. Brit, Med Journ., Sept. 6, 1902.

Arch, Gén. de Méd., Dec. 1901.

Lancet, Sept. 20, 1902.

Brit. Med. Journ., Sept. 27, 1902.

Bull. Soc. Anat. de Paris, 1901, 507.

Thése de Paris, 1902.

Centralbl. f. Gynik, 1902, No. 4.

Amer. Jowrn. of Obst., lvi. 75.

Brit. Med. Jowrn., Feb. 8, 1902.

Journ. del Anat. et dela Phys., tt. xxvii. et xxviii.

. R. Ace, d. Sei, dell Ist. di Bologna, i. 1899, ii. 1900, iii. 1902.

Monats. 7. Geb. u. Gyn., Feb. 1902.

. Nederland Tijdschr. v. Geneesk., 1901, pt. 2, No. 11.

Presse Méd., Mar. 22, 1902.

Bull. du Mus, & Hist, Nat. Paris, 1901. |
Brit. Gyn. Journ., May 1902.

Proc, Assoc. Amer. Anatomists, 1900.

. Bull. et Mém. de la Soc. d Anthrop, de Paris, 1901, 274.
. Atti del? Acc. Gioenia di Sci. Nat. in Catania, s. iv. vol. xv.

Bull. Soc. Anat. de Paris, 1902, 410.

. Anat, Anziger, xx. 305.
. Ibid., ibid., 571.

Centralbl. f. Gyniik., No. 15, 1902.
Sei-i-Kwui Med. Jl., Mar. 31, 1902.
Centrabl. 7. Gynik., No. 6, 1902.

. Monats. f. Geb. u. Gyn., 1902.

Brit. Med, Journ., Feb. 22, 1902.
Ibid. , Apr. 5, 1902.

i. Ibid., Apr. 12, 1902.

i. Soc, d’ Agric. Sci. et Ind, de Lyon,, 1901 (Rept. ).
. Arch. f. Klin. Chirurg. , \xiv., 1901.

. Centralbl. 7. Gynaik., 1902, 39.

Trans. Wisconsin Acad., vol. xiii.

i. Lyons, 1901 (reprint).

C. R. Soe. de Biol., 1900.

. Boston Med, and Surg. Jowrn., exivi. 361,
. Bibl. Anat., 1901, f. 5-6.

312 PROFESSOR BERTRAM C. A. WINDLE.

xli. Bibl. Anat., xl. f. 1.
xlii. Verh. d. Dtsch. Zool. Ges., 1902.
xliii. Anat, Anzeiger, xxi. 497.
xliv. Nowy. Iconog. de la Salpttriére, No. 3, 1902.
xlv. Anat. Anzeiger, xxi. 321.
xlvi. Studies from the R. Victoria Hosp. Montreal, i. No, 2.
xlvii. Brit. Med. Jowrn., May 10, 1902.
xlviii. Bull. et Mém. de la Soc. @ Anthrop. de Paris, 1901, 333..
xlix. Gio. Internaz, delle Sci, Med., May 15, 1902.
1. Brit. Med. Jowrn., May 3, 1902.
li. Lbid., ibid
lii. Bull. Mus. d’ Hist. Nat. Paris, 1901.
liii. Bruwelles, 1902 (reprint).
liv. Brit. Med. Jowrn., Sept. 27, 1902.
lv. Jowrn. of Anat. and Phys., xxxvi, 356.
lvi. Monit. Zool. Italiano, xiii. 1.
lvii. Arch, di Ortopedia, Aug. 1901.
lviii. Brit. Med. Journ., Aug. 30, 1902.
lix. Bull. Soe. Anat. de Paris, 1901, 719.
lx. Ibid., 1902, 440.
lxi. Ibid., ibid., 686.
lxii. Anat. Anzeiger, xxi. No. 5.
lxiii. Tbid., xx. 553.
Ixiv. Ibid., ibid., 374.
Ixv. Centralbl. f. Gynak., 1901, No. 45.
Ixvi. Jbid., 1902, No. 18.
Ixvii. Amer. Jowrn, of Obst., xlv. 569.
Ixviii. Bull, Soc. Anat. de Paris, 1901, 593.
Ixix. Jbid., ibid., 607.
Ixx. Anat. Anzeiger, xxii. 206.
Ixxi. Bull. Soc. Anat. de Paris, 1901, 598.
Ixxii. Rev, Mens. de Gyn. Obst, et Péd. de Bordeaux, April 1902;
Ixxiii, Bull. Soc. Anat. de Paris, 1902, 173.
Ixxiv. Jbid., 1901, 670.
Ixxv. Ibid., 1902, 177.

Ixxvi. Amer. Jowrn. of Obst., xlv. 40.

xxvii. Ibid., ibid., 59.
Ixxviii. Centralbl. f. Gynak., 1902, 2

Ixxix. Zeits. f. Geb. u. Gyn., xlvi. 39.

Ixxx. Amer. Journ. of Obst., xlv. 782, 785.

lxxxi. Bull, Soc. Anat. de Paris, 1901, 665.
lxxxii. Cin. Lancet and Clinic., Jan, 25, 1€02.
lxxxiii. Inaug. Diss, Bonn., 1901.

Ixxxiv. Lancet, Sept. 20, 1902.

Ixxxv. Bull. et Mém. de la Soc. d’ Anthrop. de Paris, 1902, 51.
lxxxvi. Bull. Soc. Anat. de Paris, 1902, 360.
Ixxxvii. Journ, de VAnuat. et de la Phys., 1901, 540.
lxxxviii. Bull. Soc. Anat. de Paris, 1902, 289.
lxxxix. Ibid., 1901, 612.

xe. Presse Médicale (date not known).
xci. Bull. Soc. Anat. de Paris, 1902, 64.

THIRTEENTH REPORT ON RECENT TERATOLOGICAL LITERATURE, 313

xcii. American Naturalist, xxxvi. 427,
xciii. Zs. 7. Morph. u. Anthrop., Bu. iv. hft. ii. s. 380.
xciv. Brit. Med. Journ., Apr. 26, 1902,
bs xev. John Hopkins Hosp. Bulletin, xii, 121.
xevi. Bull. Soc. Anat, de Paris, 1901, 485.
xevii. Bull. et. Mém. de la Soc. d Anthrop. de Paris, 1902, 274.
xeviii. Anat. Anzeiger, xx. 465.
xceix. Jbid., xxi. 263.
e. Ibid., xxii. 210,

(The reporter wishes to express his acknowledgments to the
abstracts in the British Medical Journal and American Journal of

Obstetrics for some of the above.)

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Journal of Anatomp and Phpsiology.

ON THE MEANING OF SOME OF THE EPIPHYSES
OF THE PELVIS. By F. G. Parsons, Lecturer on
Human and Comparative Anatomy at St Thomas's Hospital.

In the Morphologisches Jahrbuch are two very interesting
papers by Dr Ernst Maynert! dealing with the epipubis and
hypoischium of Reptiles, in which he points out that these
structures are formed in the mid ventral line, and probably are,
in the first instance, independent of the rest of the pelvis. It
is to the fate of these structures in the Mammals that I wish to
call attention, but, before doing so, I must make a few remarks
about the reptilian arrangement.

With regard to the hypoischium, Maynert shows what a
variety of forms it may take, sometimes being specially elon-
gated, sometimes almost entirely suppressed, sometimes bifid
at its pelvic end, at others toward the cloaca, sometimes fully
ossified, sometimes entirely cartilaginous, but always forming
a more or less perfect support for thé anterior lip of the cloacal
orifice, and earning its alternative name of ‘ Os cloace.’

Of all the reptilian pelves which I have examined, I think
perhaps that of the Sphenodon Lizard (fig. 1) will give the
fairest idea of this structure. It (the hypoischium) is attached
anteriorly between the junction of the two ischia which are
uniting to form the ischial symphysis so common in Reptiles ;
if it is carefully examined, it will be seen to continue forward
between the two ischia and then to reach the interval between
the two pubes, anteriorly to which it expands to form a diamond-

1“ Ueber die Entwicklung des Os Hypoischinm, Os Epipubis und Ligamentum
medianum pelvis bei den Eidechsen,” Morph. Jahr., 1891, p. 123; ‘* Untersuch-

ungen tiber die Entwicklung des Beckengiirtels der Ems lutaria taurica,” Morph.
Jahr., 1890, p. 537.

VOL. XXXVII. (N.S. VOL. XVII.)—JULY 1903, 22

316 MR F. G, PARSONS.

shaped plate of cartilage which is now called the epipubis, In
the specimen from which my figure was drawn, there was a
bilateral attempt at ossification in the epipubis, and to a less
extent in the hypoischium; but the point which I want specially

Fic, 1.—Pelvis of Sphenodon Lizard. -4, pubis; B, ischium;
C, epipubis; D, hypoischium. In this and the following
diagrams the cartilage is dotted and the bony epiphyses shaded.

to call attention to is that the epipubis and the hypoischium
form a continuous cartilaginous element in the mid ventral line.

In the pelvis of the Crocodiles the hypoischium is not a
distinct rod as it is in the Lizards, but in the fresh state (fig. 2)

Fic. 2.—Pelvis of young Alligator. 4, pubis; B, ischium ;
C, epipubis ; D, hypoischium.
the cartilage which forms the symphysis ischii, when it reaches
the hinder end, is continued outward from the mid line along
the caudal margin of the ischium, and approaches the condition
of things which I mean to deal with next.

MEANING OF SOME OF THE EPIPHYSES OF THE PELVIS. 317

_ We now leave the Reptiles for the Mammals, and in these
Maynert says that he found a bone like a hypoischium in eleven
species, nine of which belong to the order of Marsupialia, the other
two being the Pangolin (Manis, once called Pholidotus) and the
Beaver (Castor). I can quite agree with his statement that the
bone is here, and to my mind it seems evident that not only is
it like the hypoischium, but that it 7s the hypoischium, I have,
through the kindness of Prof. Stewart and Mr Oldfield Thomas,
been able to examine all the pelves in the College of Surgeons
and Natural History Museums, and certainly the Marsupials
are the most instructive. If the pelvis of quite a young

v

Fic, 3.—Pelvis of young Kangaroo. 4, pubis ; B, ischium ;
C, epipubis ; D, hypoischium.

Kangaroo, for example, is examined, it will be seen that the
symphysis is ischio-pubic (fig. 3), and not altogether pubic as in
Man ; consequently the hind part is formed by the ischium of
each side very much as in Sphenodon. In addition to this
there is the same tract of cartilage that was seen in Sphenodon
connecting the pubes and ischia of opposite sides, while behind
(caudad) the symphysis this cartilage forms a triangular plate
filling up the subpubic or, to be more accurate, the hypoischial
angle, and reaching outward as far as the tuberosity of the
ischium on each side. At the anterior (cephalic) end of the
symphysis the cartilage expands somewhat and forms a triangular
plate corresponding exactly ‘in position with the epipubis of
Sphenodon.

$18. MR F. G. PARSONS.

- In an adult Kangaroo’s pelvis (fig. 4) all the part behind the
symphysis becomes ossified and forms a triangular bony plate,
the lateral angles of which stretch outward as far as the
tuberosity of the ischium, while the part in front of the pubis
also ossifies and forms a small triangular bony plate which
corresponds * entirely ‘with the epipubis. These bones can
hardly be spoken of as epiphyses, since in quite adult Kangaroos
they are ununited with the rest of the pelvis, and I doubt
whether the hypoischium ever unites with it, though of this I
cannot be sure. . . .

If an intermediate stage, in which the ossification is in
progress, be next examined, the bone will be seen to be

Fid. 4,—Pelvis of adult Kangaroo, A, pubis ; B, ischium ;
@, epipubis ; D, hypoischium:
deposited in two or even three centres in each half of what I
may provisionally speak of as the hypoischium (fig. 5); one
centre appears on each side near the middle line and in very
much the same position in which the centres appear in Spheno-
don, another forms a cap over the dorsal part of the tuberosity
of the ischium, while occasionally there may be a third one
between the two. With regard to the ossification of the
epipubis, I have not been fortunate enough to see how the bone
first appears, but I have little doubt that it is deposited
symmetrically as in Sphenodon; indeed, I think it is very
doubtful whether in the whole vertebrate skeleton there is such
a thing as a true median centre of ossification. I am not, how-.
ever, so much concerned with the way in which the first bony

MEANING OF SOME OF THE EPIPHYSES OF THE PELVIS. 319

deposits are laid down as to establish the great likelihood that
the cartilaginous layer in the young Marsupial is the same
morphological element as the epipubis and hypoischium of the

Reptile as shown in Sphenodon. If this is granted, it matters

little, I think, how the bone is deposited; it may be by one centre
on each side in one animal, and by two or three in another,
depending largely on the length of the cartilaginous strip which
has to be changed into bone. Against the theory that this
cartilaginous strip of the marsupial pelvis is the reptilian
epipubis and hypoischium, I have only as yet heard one
objection from the morphologists I have talked to on the

Fic. 5.—Pelvis of young Wallaby. 4, pubis; B, ischium ; C, epipubis ;
D, D, D, separate ossifications in the hypoischium,

subject; some of them have a general objection to homologising
any mammalian epiphysis with that of Reptiles, because the
latter are said to have no epiphyses to their long bones. I am,
however, convinced that this is an erroneous belief. It is quite
easy to prove that epiphyses are common in Reptiles though
they are not so numerous as in Mammals.

In the Monotremes Maynert says that he has failed to- find
any trace of the hypoischium and epipubis; I feel fairly sure,
after examining many specimens of Ornithorhynehus, that in
that animal, at least, they are present, but they fuse very early
and very completely with the rest of the pelvis, and in this way
differ markedly from the similar marsupial structures, In the
Rodents (fig. 6) and Ungulates the hypoischial element is quite
distinct, and the symphysis is still ischiopubie, but the’ ossi-

320 MR F. G. PARSONS.

fication of the hypoischium does not quite unite with its fellow
of the opposite side in the middle line, and so no triangular
plate of bone is found as in the Kangaroo. The reason for this
doubtless is that the young of these animals are born in a more

Fic. 6.—Pelvis of Viscacha. 4, pubis; B, ischium ;
D, D, hypoischium.

developed state than are the marsupial young, and it is necessary
that the symphysis should be able to gape. somewhat during
parturition.

When we come +o the pelvis of Man we have to deal with

Fic. 7.—Human pelvis at twelve years of age. A, pubis ;
B, ischium ; C, epipubis ; D, hypoischium.
a pubic symphysis only, otherwise at about twelve years of
age (fig. 7) the likeness to the marsupial and reptilian arrange-
ment is striking. There is a continuous edging of cartilage,
which begins as a little cap over the pubic spine, lines the

MEANING OF SOME OF THE EPIPHYSES OF THE PELVIS. 321

crest, angle, and symphysis, and then runs along the subpubic
arch as far as the tuberosity of the ischium, for -which it forms
a well-marked cap. This, I have no doubt, is the same structure
as that of the young Kangaroo, and represents the continuous
epipubis and hypoischium of the Reptile.’

Ossification begins at the two ends of this cartilaginous
edging, but there may be more than one deposit in each place.
In the College of Surgeons Museum there is the pelvis of a
boy of 14 which shows (fig. 8) the presence of two
deposits of bone beneath the tuberosity of the ischium, and
one smaller at the angle of the pubis. At 16 there is a com-
plete bony cap for the tuberosity of the ischium, which quickly

Fic. 8.—Human os innominatum at fourteen years of age. A, pubis ;
B, ischium; C, epipubis ; D, hypoischial ossification.

creeps along the cartilaginous edging, and about 20 (fig. 9) has
ossified that edging as far as the point of union of the rami
of the pubis and ischium—that is to say, it goes morphologically
as far as it does in the Kangaroo, in which the symphysis is
ischio-pubic. I think that I have now said all I can in support
of my belief that the hypoischium of the Reptile explains the
presence of the epiphysis of the tuberosity of Man’s ischium.
With regard to the epipubis, it is interesting to notice that in

?In Sphenodon these two elements are directly continuous by cartilage, but
in many other Lizards the part between the pubic symphysis and that of the

ischium is often converted into a median ligament, owing to the fact that the
two symphyses are far apart.

322 MR F. G. PARSONS.

the young human subject the cartilaginous border runs outward
as far as the pubic spine, and so with its fellow of the opposite
side forms a triangular plate very like the epipubic bone of
the Marsupial.

The first deposit of bone is, as I have shown, and as Thomas
also notices,! at the angle of the pubis, and so closely cor-
responds with the centre in the epipubis of Sphenodon. Later
on this ossification creeps downward as a thin scale along the
pubic symphysis and also outward along the crest of the pubis
as far as the pubic spine. Sometimes a small distinct deposit
is said to appear for the pubic spine, and this may be looked

F Ig. 9. —Human os innominatum pe uate years of age.
D, hypoischial epiphysis.

on as a disappearing remnant of the marsupial bone which
Wiedersheim regards as part of the epipubis. I have never
been fortunate enough to see this centre, but one point which
makes me a little doubtful of its homology with the marsupial
bone is the fact that the spine of the pubis is quite a human
characteristic, and is apparently a physiological result of the
pull of Poupart’s ligament. In the lower Mammals Poupart’s
ligament as a definite structure can hardly be said to exist. —

3 Cimnisiiits aan! s Teat-Book of priate ie ps 213. Phoriweoth gives the date of the

appearance of this epiphysis,as 18 years. The. specimien in the ay C. 8. Mentions
which I quote shows that it may come four years earlier, © 0° = kt

MEANING OF SOME OF THE EPIPHYSES OF THE PELVIS. 323

The only other pelvic epiphysis of which I wish to speak at
present is that for the anterior inferior spine of the ilium, and
I do so because it makes such a sharp contrast with those with
which I have been dealing. Although I have now looked at
the pelves of very many young Mammals, I have never yet
found this epiphysis in any other animal than Man. Whena
new structure is met with-in Man, one is always inclined to
seek an explanation in the erect position, and here I think a
clue may be found. In Man the straight head of the rectus
is much stronger than in other Mammals, and, from the position
of the limb, pulls harder on the bone; and I think that the
anterior inferior spine is one of those traction epiphyses, nearly
akin to sesamoid bones, which so often come where a strong
pull has to be met. In this, if I am right, it is like the spine
of the pubis or the lesser trochanter, and greatly differs from
the epiphysis of the ischial tuberosity which leads us back to
reptilian days, or from that of the symphysis pubis which goes
still farther back to the tailed Amphibia.

ON THE SO-CALLED ‘GYRUS HIPPOCAMPI’ By G.
Exuiot Smiru, M.A., M.D., Fellow of St John’s College,
Cambridge ; Professor of Anatomy, Egyptian Government
School of Medicine, Cairo.

In a recent number of this Jowrnal! I called attention to the
fact that the true pallium really consists of three morpho-
logically distinct parts:— hippocampus, lobus pyriformis, and
neopallium, The latter presents the utmost contrast to the
other two pallial areas, not only in its histological structure and
physiological characters, but more especially in regard to its
behaviour in the mammalian series. This can be expressed in a
word by saying that the neopallium is eminently progressive,
whereas the hippocampus and pyriform lobe are stationary or
even actually retrogressing in the recent Mammalia.

If the validity of this mode of subdividing the pallium be
admitted, we must of necessity discard as useless and confusing
the terms ‘gyrus hippocampi’ and ‘gyrus uncinatus, because
the area so-called is composed partly of neopallium (fig. 1,
‘paradentate gyrus’) and partly of pyriform lobe, with the
addition of small areas of hippocampus (fig. 2,@ and 6) and
nucleus amygdale (n.am.). The latter is a large ganglionic
mass which does not strictly belong to any of the three pallial
areas: it is continuous above with the corpus striatum, in front
with the locus perforatus, behind with the hippocampus, and
below with the pyriform lobe: a small part comes to the
surface, and it is, I believe, not generally recognised that the
structure which Gustav .Retzius (op. cit. infra) calls ‘gyrus
semilunaris’ (in the human brain) and ‘gyrus lunaris’ (in the
brains of other mammals) is nothing else than this exposed
part of the nucleus amygdale (figs. 1 and 2, n.am.).

It is quite unnecessary to give a full account of this region,
because Retzius? has described it in great detail, and in an
earlier memoir? I have called attention to its salient
features.

1 Vol. xxxv., July 1901, ‘‘ Notes upon the Natural Subdivision of the
Cerebral Hemisphere,” pp. 431-454.

* Gustav Retzius, Das Menschenhirn, Stockholm, 1896.

3 **The Relation of the Fornix to the Margin of the Cerebral Cortex,” This
Journal, vol. xxxii., 1897, p. 29.

SO-CALLED ‘GYRUS HIPPOCAMPI.’ 325

That the region labelled ‘pyriform lobe’ really represents
the posterior part of the lobus pyriformis is abundantly shown,
not only by its histological features, but also by a comparison of
the human organ with other mammalian brains. This fact has
been very clearly demonstrated by Retzius,' and I have recently
shown how the pyriform lobe in the Primates becomes gradually
modified in form, from a condition exactly comparable to that
of most mammals to the human-like form of the lobe found in
the Gorilla.

The pyriform lobe in the human brain extends backward as

corpus callosum

tas oo tiga ees ye Ge
i :pyrifdtin: lobe ©;

- . *.*

rhinal fissure

Fic, 1.—Part of the mesial surface of the right cerebral hemisphere of a Fellah,
6, et, 62 ann,, nat, size,

far as a point opposite the tip of the uncus (which is formed of
a little knob (0) of inverted hippocampus which Retzius calls
‘gyrus intralimbicus’).
The chief reason why the pyriform lobe has not hitherto been
? Gustav Retzius, ‘* Zur iiusseren Morphologie des Riechhirns der Siiugethiere
und des Menschen,” Biologische Untersuchungen, Bd. viii. No. 2, Stockholm,
1898.

2 Descriptive and Illustrated Catalogue of the Royal College of Surgeons,
second edition, vol. ii., 1902, See especially p. 441.

326 PROF, G. ELLIOT SMITH.

generally recognised in: the human brain is that the rhinal
fissure, which delimits this area, is subject to so much
irregularity that its identity has not been appreciated by most
writers. In fact, Retzius is the only writer, so far as I am
aware, who has recognised the full extent of the rhinal fissure
in the human brain. The typical form of this fissure, such as
is exhibited in the brain of the ‘Apes, is not often seen in the
European brain, but that it does sometimes occur is shown by
Retzius.'. The latter writer also shows the characteristically

tr. olf.

AUK uy XX a a
YK ’ Bai

° ¢ A
TANKS fst

pyriform lobe

rhinal ~ fissure

Fic. 2.—Part of fig. 1 enlarged. a, the ‘ benderella’ of Giacomini, 7.¢., the
anterior (lower) extremity of the fascia dentata; b, the tip of the uncus,
composed of alveus-coated inverted hippocampus; c, dorsal tongue-like
process of the pyriform lobe ; d, a very constant furrow on the pyriform
lobe ; x.am., exposed part of the nucleus amygdale ; ¢.olf., external
olfactory tract ; ped.olf., the posterior part of the pedunculus olfactorius ;
inc., incisura temporalis (part of the rhinal fissure).

mammalian form of complete rhinal fissure exhibited in the
human foetus,?

The primitive form of rhinal fissure (see the figure) occurs
much more often in the brains of Egyptians and Abyssinians
than it does among Europeans, and among the Soudanese races
it is of common occurrence.

In the European brain, however, the posterior part of the

* Menschenhirn, Vide Tafel lx., inter alia, ? Op. cit., Tafel xxxii. fig, 2.

SO-CALLED ‘GYRUS HIPPOCAMPI.’ 327

fissure usually becomes separated from the incisura temporalis
(fig. 2, ine.), and often becomes confluent with the sulcus col-
lateralis! In fact, most writers have come to regard this caudal
part of the rhinal fissure as the anterior part of the collateral

suleus. To understand how unfounded such an idea is, I
~ need only recall the fact that the rhinal fissure is, next to the
hippocampal fissure, the oldest furrow on the surface of the
hemisphere and the common property of all mammals (not ex-
eluding even the Monotremata); whereas the collateral sulcus
is a recent formation which is only properly developed in the
higher Primates.”

The wide range of variation and distortion of the rhinal
fissure which occurs in the human brain is admirably shown in
the beautiful series of plates in Retzius’ great work.

For the reasons stated above it is desirable to separate the
‘pyriform’ part of the uncinate gyrus from the non-pyriform
or neopallial part. The neopallial part of the gyrus cannot then
be named ‘uncinate,’ because the whole region of the uncus is
excluded. In addition, it is highly undesirable to perpetuate
the use of the term ‘hippocampal’ in reference to this con-
volution. Such a usage has in-the past been the cause of an
immense amount of confusion in the literature of Comparative
Anatomy. Very many anatomists, including the most prolific
writers on Comparative Neurology in Europe and America,
constantly fail to draw any distinction between the hippocampus
(cornu. Ammonis) and the ‘hippocampal gyrus’ (which is part
of the neopallium); and the result of this is the most hopeless
misunderstanding. As this is wholly due to the similarity of
the names, I propose to discard the term ‘hippocampal gyrus,’
and to call the neopallial part of the uncinate convolution by
the name ‘gyrus paradentatus, in reference to the fact that it
pursues a course parallel to the fascia dentata, from which it is
separated by the hippocampal (dentate) fissure.

Nor does it seem desirable to retain the term ‘gyrus
uncinatus’ in reference to the anterior (rhinencephalic) part of
the convolution. For one reason, an essential part (fig. 2, @

1 Vide, for example, Menschenhirn, Tafel lxxv. fig. 4.
2 “*On the Homologies of the Cerebral Sulci,” This Journal, vol. xxxvi., 1902,
pp- 309-319.

328 SO-CALLED ‘GYRUS HIPPOCAMPI.’

and b) of the hook (wneus) is hippocampal, and therefore ought
to be considered as part of the hippocampus, and not be grouped
with the pyriform lobe. On the other hand, it would be a
distinct gain, not only to Comparative but also to Human
Anatomy, if the region which is homologous to the pyriform
lobe of other mammals were called by the same name in the
human brain. If it be objected that the use of the term ‘lobe’
might lead to some confusion (because the human brain is
already conventionally divided into ‘lobes’), the term ‘area
pyriformis’ might be employed to indicate that region of the
human brain which represents the posterior (postsylvian) part
of the pyriform lobe of other mammals.

The so-called ‘ uncinate’ or ‘ hippocampal’ gyrus thus becomes
split up into four separate areas:—paradentate gyrus, area
pyriformis, nucleus amygdale, and a hippocampal part.

It may be asked why the term ‘gyrus’ is not applied to the
pyriform area, I have intentionally refrained from using this
expression, because every gyrus in the cerebral hemisphere will
then be a part of the neopallium—a distinction which seems
worthy of being maintained. If, however, we were to follow
some writers who call the fascia dentata a ‘gyrus,’ there would
then be no reason why the pyriform area should not also be
so called, Gustav Retzius, in fact, applies the term equally to
the neopallium and the rhinencephalon. Nothing is gained by
such a use of the term gyrus, whereas a useful distinction is
maintained if this word is applied only to the neopallium.

It must be remembered that the area we have been consider-
ing includes only the posterior part of the pyriform lobe. The
anterior part (as in all the Apes) dwindles to very small pro-
portions, and its situation is indicated merely by the lateral
olfactory tract (fig. 2, ¢r.olf.), which passes backward from the
olfactory peduncle (ped.olf.), skirts the lateral border of the
locus perforatus, and, after crossing the deep vallecula Sylvii,
reaches the surface of the posterior part of the pyriform lobe.

None of the facts brought forward in these notes are new.
The suggestions which I have made give expression to the
teaching of Comparative Anatomy, which has too long been
ignored in the domain of Human Anatomy.

NOTES ON THE MORPHOLOGY OF THE CEREBELLUM.
By G, Exuior Smitn, M.A., M.D., Ch.M., Fellow of St
John’s College, Cambridge ; Professor of Anatomy, Egyptian
Government School of Medicine, Cairo.

In a short memoir published in this Journal last year! I briefly
explained the mode of subdivision and the nomenclature of the
cerebellum which I had adopted in three works dealing with the
brain in every mammalian Order.”

In the first of those three monographs I explained at some
length the urgent need for some mode of subdividing the cere-
bellum other than that adopted in Human Anatomy, which is
altogether unsuitable, and in most cases quite inapplicable, in
Comparative Anatomy.

The earlier investigations of Kuithan and Stroud had shown
that in three such diversely-specialised and widely-separated
mammals as Ovis, Felis, and Homo the chief fissures of the cere-
bellum develop in the same manner; and my examination of
the brain in practically every existing genus of the Mammalia
showed these same fissures to be distinguished by their depth
and constancy.

I attempted to draw up a scheme of subdividing the organ,
based upon the recognition of the facts demonstrated by these
two lines of investigation.

The only region presenting. any difficulty was that including
the connecting strands of grey matter which link the floccular
lobe to the ‘vermis. Neither Stroud nor Kuithan had
discussed the nature of this connection; but I discovered that
“in the smallest representatives of every Order—as, for example,
Perameles, Dasyurus, Trichosurus, and most Marsupials, in all
Insectivores and Chiroptera, in most Rodents, in the Dasypodide,
in Procavia of the Ungulata, and in such Lemuroids as Jarsius

1 “The Primary Subdivision of the Mammalian Cerebellum,” This Journad,
vol, xxxvi., July 1902, pp. 381-385,

2 (a) ‘*The Brain in the Edentata,” Transactions of the Linnean Society of
London, vol. vii. part vii., 1899; () The Descriptive and Illustrated Catalogue
of the Royal College of Surgeons of England—Physiological Series, 2nd edition,
vol, ii,, 1902; (c) ‘The Morphology of the Brain in the Mammalia—with Special

Reference to the Lemurs,” 7'ransactions of the Linnean Society of London, vol. viii.
part 10.

330 PROF, G. ELLIOT SMITH.

and Microcebus—there is a simple undivided band joining the
dorsal paraflocculus to the pyramid” [op. cit. supra, (1), p.
384]. The pyramid is the lowest (most caudal) lobule of the
region I called the ‘middle lobe,’ and is separated from the
uvula (which is the uppermost lobule of the ‘ posterior lobe’)
by the fissura secunda (which probably corresponds to the
‘ prepyramidal fissure’ of Human Anatomy).

SsuP PED.

LOBUS ANT-
FISS PRIMA, —

FISSURA PARAFLOCC.

PARAFLOCC..

SECUNDA,

Fic. 1.—Diagram to represent the fundamental subdivisions of the cerebellum
; spread out in one plane,

In a recent number of this Journal! a thinly-veiled attack has
been made on my position in regard to this matter by a writer,
who shows a singular reluctance to add point to his observations
by referring in any way to the offending statements. Yet it is
clear that this question of the relation of the paraflocculus to
the vermis is the raison d’étre of that document, because all
the other matters discussed merely exemplify, in the case of
the Rabbit, the fundamental structure of the cerebellum, which
the researches of Kuithan, Stroud, and the writer have shown
to prevail in all the Placentalia.

We are told [op. cit., (3), p. 121] that in the adult Rabbit it is

1“ On the Development and Homology of the Mammalian Cerebellar Fissures,”
This Jowrnal, vol. xxxvii., January 1903, pp. 112-180.

NOTES ON THE MORPHOLOGY OF THE CEREBELLUM, 331

the uvula (‘lobe D’) which is joined to the paratlocculus; and
“the ground upon which his statement is based” is that it does
so. in the Hare’s cerebellum! The author then proceeds to state
that the uvula (‘lobe D’) is “contined to the vermis” (z¢., is
not joined to the paraflocculus) in Hrinaceus (p. 123), Mus
(p. 125), Arvicola (p. 125), and Pleropus (p. 126), and from these
data formulates the illogical general conclusion that the uvula
(‘lobule D, «¢., the. upper part of ‘lobe D, which is equivalent
to the uvula) zs joined to the dorsal limb of the paraflocculus
(p. 128). In other words, the author of this generalisation

MEOULL. BAND

\ PARA
COPULA PYRAMIDIS UVULA FLOCCULUS

Fic. 2.—The caudal aspect of the cerebellum of a Rabbit (Lepus cuniculus). x 3}.

places the evidence of a (presumably anomalous) Hare’s brain
in opposition to his own statements concerning the condition
in Erinaceus, Mus, Arvicola, and Pteropus, not to mention the
evidence which I have collected in the four memoirs quoted
above.

I have examined the structure of the cerebellum in a large
number of Rabbits in reference to this disputed point. In the
majority of these I have found the condition represented in the
accompanying drawing (fig. 2). The narrow dorsal limb of the
paraflocculus is joined by means of a long, narrow, wrinkled
band of grey substance (copula pyramidis) to the pyramid, of
which two broad folia are usually exposed on the surface. In

VOL, XXXVIL. (N.S. VOL. XVIL.)—JULY 1903. 23°

332 NOTES ON THE MORPHOLOGY OF THE CEREBELLUM.

most cases the upper margin of this copular band is very
sharply delimited from the (other) folia of the area C by a deep
fissure continuous with that bounding the pyramid on its dorsal
aspect. But in some cases the upper folium of the pyramid
becomes continuous with the folia of area C—an arrangement
which invariably occurs in the Apes (including both Cebide
and Cereopithecide). In one case the lateral extension (copula)
of the pyramid did not réach so far as. the paraflocculus. —
In no case, however, did the copular band (or any other para-
floccular link of grey substance) join the uvula. In fact, among
the very large series of mammalian brains which I have ex-
amined in regard to this particular feature during the last five
years, I have seen a (macroscopic) cortical connection between
the parafloceculus and the uvula only in the human brain and
in single anomalous specimens of foetal 7’richoswrus and Bos.

When I was writing my short abstract (op. cit. supra) last
year I carefully examined a complete series of sagittal sections
through the brain of Notoryctes,1 which possesses a simpler cere-
bellum than any other mammal.? In that organ I found a
narrow band of cerebellar cortex (which was quite invisible to
the naked eye) lying below the copula pyramidis (fig. 1): it was
continuous mesially with the cortex of both uvula and nodulus,
and laterally with the flocculus and the ventral part of the para-
flocculus. It occupied, in fact, the same position as the
medullary band (fig. 2), visible to the naked eye in most other
mammals. This, however, cannot be the structure referred to
in the critique quoted above, because a macroscopic cortical
band passing to the dorsal limb of the paraflocculus from the
uppermost lobule (only) of the uvula is meant. |

In my notes published in this Journal last year (op. cit.
supra, vol. xxxvi. p. 384) there is an important misprint. I
referred to the fissura horizontalis magna as separating the
areas A and B, but as the context clearly shows it is the furrow
between the areas B and C (fig. 1).

1 Five specimens of this interesting Marsupial were generously placed at my
disposal by Professor Baldwin Spencer of Melbourne, whom I desire to thank
for his valuable gift.

? The only fissures crossing the middle line in this curious little organ are the
fissura prima, the fissura secunda and the cleft separating the uvula and nodulus.

al al nl 4

-A PRELIMINARY COMMUNICATION ON SOME CEPH-

ALOMETRIC DATA BEARING UPON THE RELA-
TION OF THE SIZE AND SHAPE OF THE HEAD

~ TO MENTAL ABILITY. By Dr Recinatp J. GLADSToNnE,
F.R.CS., Senior Demonstrator of Anatomy, Middlesex
Hospital, London, W.

A LARGE amount of laborious and painstaking work has been
undertaken, both recently and in times which may be regarded
as historical, with the view of determining the relationship, if
any, between different types of head and various mental
characteristics or degrees of ability. The results of this labour
appear, until the last ten or fifteen years, to have been some-
what indefinite and often contradictory.

Some of the older physiognomists and phrenologists, and
notably Lavater and Gall, attained a high degree of proficiency
in estimating the character and disposition of individuals, by
means of a careful observation of external features, and their
published works are not only of great interest, but contain also
valuable scientific data. The conclusions drawn by others,

_ however, were for the most part founded upon hypotheses rather

than on observations, and are of little value to the psychologist.
_ Recently articles have appeared also in some of the popular
journals which are based on materials furnished by hat manu-
facturers, and which are illustrated by remarkable tracings
which are said to have been taken by the ‘ hatter’s machine’
for recording the outline of the head; these are interesting,
but for the most part absolutely untrustworthy. One table of
figures, which has been compiled by a well-known straw-hat
manufacturer, and for which I am indebted to the kindness of
Mr A. Pearce Gould, for whom it was originally drawn up, is
of considerable interest, and I venture to introduce it here, for
the purpose of showing how easily mistakes may arise from
these kind of data, however carefully they may be formulated.

The table shows the relative frequency of various specified
sizes of straw-hat supplied for the use of boys and men in the
years 1868 and 1901-2. The figures have been averaged from
a large number, and reduced in-each case to two dozen.

334 DR REGINALD J. GLADSTONE.

TABLE I.

Size of hat— | )
Length, ¢ E 6” 64" 63” 63” 64 68” 63" 62” Yh 7h" 7" 78" | 74"
Circumference, |183”| 193” 198"| 20” | 208 | 203"|214”|218"| 22” |228"|222"934" 233”

|

Boys, 1868, od hameeihece stad oa BrelBalca cys 1 | = | 2 dozen |
901 ES a ae en a ee es = | 2 dozen |

Men, 1868, an Maries banierr IMac! nes jars | 3] 5 |5 | 4 | 4 42=2 dozen
93 LOOT 2 yahoo ee, gk eee 3 5 7 6 2 1 =2 dozen

This table shows a marked decrease in the sizes of hat which
were supplied in the year 1901-2 as compared with the sizes
which were sold in 1868, both in boys and men. If during this
period there had been a diminution in the size of the men’s
heads, corresponding to the diminution in the size of hats,
shown in the two lower lines of the table, and if this diminution
were to continue at the same rate until the year 1968, the
English Nation would then have heads smaller than the average
Andaman Islander, and they would soon be reduced to the
condition of microcephalic idiots. Fortunately for the coming
generation we need not anticipate such a change, and we may
account for the difference in the figures by variations in
circumstance, apart from diminution in size of head—ey., a
difference in the mode of wearing the hat, and in the fact, as
evidenced by photographs, that it is customary now to have the
hair much more closely cropped than was the fashion in 1868.
On considering the more recent statistics relating to measure-
ments of the head and skull, it soon became evident that in
order to obtain more definite results than hitherto, it would be
necessary to draw my figures from a few well-defined classes
of individuals who were living under approximately the same
conditions; to keep these classes separate; and, in comparing
the measurements of the classes with one another, and of the
individuals composing each class, to contrast the extremes with
one another, rather than to compare either extreme with a
general mean; further, that the actual measurements should
be recorded in the tables, or the number of measurements -
falling between certain figures lying close together (¢g., the
number in each class having heads measuring in height from
130-134 mm, and from 135-139 mm., etc.), rather than

ares.)

SIZE AND SHAPE OF THE HEAD. 335

counting the number falling above or below a certain general
average.

One of my chief objects in this investigation has been to
ascertain for myself whether, or not, there is a distinct increase
in the size of the head and brain commensurate with an increase
in the standard of mental ability ; and conversely, whether there
is or is not a decrease in size of head and brain correlated with
a decline in intellectual power. The question involves the
consideration of many others, and in dealing with it a number
of circumstances have to be taken into account—eyg., if it be
granted that an increase in the size of head is associated with
an increase in the standard of mental ability, is this increase in
the size of the head simply proportional to, and correlated with,
an increase of stature and body-weight, the result of the more
favoured conditions under which a higher and more intellectual
class of society is living? or are the gold medallists and prize-
winners in a school or college a few years older than the others ?
and is the greater size of head in the former due to the natural
enlargement of the head accompanying growth? also to what
extent is the question complicated by the mixture of different
types of individuals ? further, does the emotional side of a person’s
organization, or the degree of muscular development, have any
influence on the size and shape of the head, and if so, is the
development of either or both of these in a high degree opposed
to a high standard of mental ability, or may the three conditions
all coexist in a highly developed state and be associated with
an unusually large brain and head? Some of these questions
have been very ably dealt with already by others, and may be .
considered to be more or less definitely answered, while others
remain questions still. In certain cases the collateral con-
ditions have not only been demonstrated to exist and to exert
an influence on the size and shape of the head, but the degree
of the influence has been quantitatively estimated, and the
amount may be added or deducted from the general results of
the investigation. The majority of these conditions, however,
remain, and will continue to remain, quite unmeasurable; and
their influence, which may be considered to account for a certain
number of exceptional cases, must be counterbalanced by
measuring a sufficiently large number of individuals, so that

336 . DR REGINALD ‘J. GLADSTONE.

their chance effect. upon any one class or subdivision may be
reduced to a minimum.

The kind of influence that collateral conditions may have
upon the question which is the subject of this paper, may be
illustrated in the following manner. Let us suppose that the

Table IT

dt

ge Type ome

21 pa
- Bo ii\ Bi

19 ‘ a . ia | a

ete an ite Typel | \ car

“7 ey z

18 [ 16 4
as |. | \ poe
S44 : 1 . 2
gus Ws \ \ 13 3
aie / \ | ty +I 2
“ : MT Zi\ n %
g —2 \|/ 7 x ee
= Ly Typel ee Oi 1 9 2
5s j I Bs rh j H s g
a2 HLT per A el TAT Ti anf
= 6 | ¢ PA t bir 7 ne © a

+5 jor Y \ 7 . . } .

4 SS xy \ iy / \ ‘ | 2

S J wd \ Sa f Dy, \ \ >

2 [i ey he SG X -

s | lf i SPN weet

A im te KR)
laden of Bi Q g} of} O° 9] Oo] o fs)

total number of individuals measured belong to two types, one
characterized by having a small head which we will call Type
I., the other by a large head which we may speak of as Type
Il. If we draw out a‘ frequency polygon’ (see Table I.) showing
the number of individuals having heads corresponding to
successive degrees of size, the figures denoting which are placed
along the abscissa A.B., the polygon will probably have two

SIZE AND SHAPE OF THE HEAD. 337

main peaks, the apices of which will, by their position, indicate
the size of head most frequently met with in the corresponding
type; it will be seen that the apex of the peak corresponding
to Type I: is opposite the figure 3950, and that of Type IL.
opposite 4150, while there is a marked drop between them
at 4050. .

Let us further suppose that in each type there are individua
with a high degree of mental ability, and having heads relatively
larger than those with a low degree of ability and belonging to
the same type, and let us call the former Class A, and the latter
Class C, and let us leave out of consideration altogether the
individuals of average intelligence, who would fall into an inter-
mediate Class B, and let us map out the curve for each of these
two classes within the main curve corresponding to the total
number. Each class will be seen to have two type peaks, which
lie within the corresponding peaks of the main curve; but the
peaks of Class A will be a little to the right of the correspond-
ing peaks of Class C, and will thus indicate that in each type
Class A have generally larger heads than those of Class C,
although the individuals composing Class A and belonging to
Type I. will have smaller heads than those of Class.C belonging
to Type II. Moreover, if the average size of head of Class A
in both types taken together. be compared with fhe corre-
sponding total average in Class C, it will be found to exceed the
latter.

The apparent exceptions, therefore, to the rule that individuals
with great mental power have generally larger heads than those
with small, are easily accounted for by supposing that these
exceptions belong to a type or race of men characterized by the
smallness of their heads; and it will be seen also that the total
averages of each class will, provided the number of individuals
be sufficiently large, only be very slightly affected by the
difference in types.

My figures do actually show a drop corresponding in position
and extent to that represented in the main curve of the:
diagram, but the line extends in an irregular manner for a
considerable distance on each side beyond the limits of . the
diagram, and I wish it to be clearly understood that I have
inserted the chart merely for the purpose of illustrating. a

338 DR REGINALD J. GLADSTONE.

principle, and that it does not represent an accurate record of
my measurements.

These measurements I have grouped together in a series of
tables, most of which I have constructed on the following
simple plan. The individuals composing each group have been
divided into three classes, according to the degree of their
mental ability: these classes I have called A, B, and C. Class
A comprises the gold medallists, scholarship, and prizemen,
individuals with keen intellect, sound judgment, and versatile
in talent; Class B, those of average intelligence ; and Class C,
individuals with poor memory, slow intelligence, with little or
no power of reasoning, and conspicuously wanting in initiative
or originality. The minimum, average, and maximum measure-
ments of each class have been found and arranged in three hori-
zontal lines, Class A being above, Class B in the middle, and Class
C below; in this way three vertical columns are formed showing
the minimum, average, and maximum measurements of each of
the three classes (see Table IIT.).

The individuals which I have been able to classify in this
way belong to two main groups :—(a) the students and medical
staff of the Middlesex Hospital, of whom I have the measure-
ments of rather more than 200, and (6) the boys of St
Katherine’s School, Regent’s Park, numbering 42. In each
group the individuals comprised in Class B are the most
numerous, those in Class C the least numerous, while Class A
is intermediate in number.

Besides these two groups I have the measurements of 50
male and 100 female subjects (over 50 years of age), inmates
of the St Pancras Workhouse; and I am obtaining the
measurements of 50 male and 50 female subjects from
the post-mortem room of the Middlesex Hospital, in which
the brain-weight is recorded in addition to the outside
measurements. The latter number, however, is not yet com-
plete, and I only mention them here, because I have already
made use of them in finding a provisional ratio between
the weight of the brain and the outside measurements of the
head,

The data which I have selected as the most important, and
have employed in constructing the following tables, are the

SIZE AND SHAPE OF THE HEAD. 339

‘sex, age, weight, and stature of each individual, with the
following measurements of the head :—

1, the length of the head, from the glabella to the occipital
point.

6, the maximum transverse diameter of the head above the
level of the zygomatic arches.

h, the height of the cranium, as indicated by the vertical
distance from the biauricular line to the bregma.

¢, the horizontal circumference, taken in a plane passing in
front through a point just above the glabella and
behind through the occipital point.

I have also obtained tracings of the horizontal contour of the
head, and a full and profile photograph of the majority of in-
dividuals composing the Middlesex Hospital group, besides
other data such as the colour of the hair and eyes, the degree
of muscular development, the circumference of the chest, the
longitudinal and transverse arcs of the head, the nationality
and birth-place, and a few notes indicating the personal status
and hereditary conditions of each individual.

The longitudinal and transverse diameters have been taken
with Mr J. Gray’s callipers, a full account of which will be
found in the Journal of the Anthropological Institute, vol.
xxxL, 1901, p. 111. These have the advantage of acting auto-
matically, and thus giving the same measurements when used
by different individuals. The height of the head and the
horizontal contour have been recorded by the instruments
figured and described in the Report of the Proceedings of the
Anatomical Society, November 1901.

My first table, III., indicates the minimum, average, and maxi-
mum sizes of head among the students of the Middlesex
Hospital, including a few qualified practitioners who have at-
tended senior classes in that institution.

The figures, which give an indication of the relative sizes of
the heads measured, have been obtained by multiplying together
the three principal diameters of the head, /, 6, h, expressed in
millimetres thus—

1(196) x b(156) x h (138) = 4219/488.

340 _- DR REGINALD J, GLADSTONE.

The first four figures of this number, 4219, represent the number
of cubic centimetres which would be contained in a rectangular
block having diameters corresponding to the above diameters
of the head, and I shall refer to the number subsequently as
the Index of Size of the head; and although it is not quite
directly proportional to the actual size of the head and its con-
tents, owing to differences in shape and in the thickness of the
skull and its coverings, I have found it sufficiently so for
practical purposes.

TABLE III. ~iigdonde of the Middlesex Hospital.

Indices of Size.
Min. Aver. Max,
Class A, . : . 38849 ue 4320 add 5100.
. Class B, . i e ORB DRL eS a, 4015 At 4808

_ Class C, . : . 8486 ce 3747 ane 3990

This table shows a progressive diminution in the size of the
head from Class A to Class C, and it also shows that the man
with the largest head belongs to Class A, and the one with the
smallest to Class C. Moreover, the average index of size of
Class B (4015) is considerably above the general average of
the uneducated classes, and indicates an approximate brain-
weight’ of 1439 grammes.

1 (1) The last three figures of the total product form a fraction of a cubic centi-
metre, which will on the average amount to 4c.cm., and which I have thought
sufficiently small to leave out of consideration ; it is important, however, to use
the greatest care in taking the measurements, and, if the measurement of any or
all of the diameters of the head falls a little beyond or short of the millimetre
mark on the scale, to record the fraction, for if we compare the product J, d, h,
quoted above (196 x 156 x 138) = 4219'488, with the product of the same
diameters each increased by 0°5 mm. (196°5 x 156°5 x 138°5) = 4259'186, it will
be seen that there is the very considerable difference in the ‘index of size’ of
40 c.em. (4259 — 4219 =40),

(2) In dealing with large numbers it is not necessary, in order to find the aver-
age size of the head or other ‘ organ,’ to work out the product of the diameters
(2, 6, h) in each case and then find the mean of these products, for, as has been
shown by Dr Alice Lee and Professor Karl Pearson in the case of skulls be-
longing to various races, the mean of each of the three diameters (7, 6, #) for the
group under consideration may be found, and these three means multiplied to-
gether will give a result differing by less than 1 per cent. from the mean of the
products, to find which would entail a very much greater expenditure of time
and labour,

(Dr Alice Lee and Professor Karl Pearson, Phil. Trans. ka Soc. London,
Series A., vol, 196, p. 249 (18) ).

SIZE AND SHAPE OF THE EAD. 341

_ The next table, IV., shows the indices of size of the boys of St
Katherine’s School, Regent’s Park, the degree of mental ability
of whom was estimated by the schoolmaster engaged in teaching
them, and who..was intimately acquainted with the character
and status of each. The age of the boys ranges from 7-14
years, and the average age and — of the three classes is
almost equal.

TABLE 1V.—Soys of St Katherine’s School.
Indices of Size of Head.

ze Min. Aver. Max.
Class A, -; : . 2850 Bab? GALD ry 3998
Class B, -; : - .2951 Si) ORO PY 3657
ee sg ne BO8T Se BIBL: | 8962

It will be noted that here also-there is a progressive diminu-
tion in the average size from Class A to Class B, and that the
boy with the largest head belongs to Class A, the boy with the
smallest head, however, is also in Class A, and the maximum of
Class C is very little below that of Class <A.

Table V. gives the average indices of size for different groups,
including the Anatomists who were measured in the Anthropo-
metrical Laboratory of Trinity College, Dublin, at the meeting
of the Anatomical Society in 1898, and for the Report on the
measurements of whom I am indebted to Professor D. J. Cun-
ningham and Dr C. R. Brown.

TABLE V.—Average Indices of Size of Different Groups.

Middlesex Hospital Medical Staff, : Se OLE.
Anatomists at Trinity College, . ‘ . 4161
Middlesex Hospital Students, , Cmeaye Wey Nha:
Men in St Pancras Workhouse, .. ik 8988
Women in St Pancras Workhouse, cre? ph ced See

The following six tables show the length, breadth, and height
of the head, expressed in millimetres, of the three classes in the
Middlesex Hospital and St Katherine’s School groups; and it
will be observed, on comparing the averages, that Class A is in
all cases the highest, and that there is a progressive diminution
from A to C, except in the column showing the mean height of
head in the St Katherine’s School group, where Class C exceeds
Class B by one millimetre. The decimal points have, for the
sake of simplicity, been omitted in all cases.

342 DR REGINALD J, GLADSTONE.

TABLE VI.—Middlesex Hospital.
Length of Head.

Min. Aver. Max.
Class A, . i . 189 ae 199 Sik 209
Class B, . ci . 183 <3 196 oe 210
Class C, . 4 . 188 sa 193 bate 201

TABLE VII.--St Katherine’s School.
Length of Head.

Min. Aver. Max.
Clas A, 6 1. 198) ae
Class B, . F e170 bes 183 Ay 194
Class C, . F 4 TS axe 179 as 188

TaBLE VIII.—Middlesex Hospital.
Breadth of Head.

Min. Aver. Max.
Class A, . . . 141 eee 154 eee 163
Class B, . ; . 188 id 153 eat 163
Class C, . P 15540 ‘es 148 ode 155

TABLE LX.—St Katherine's School.
Breadth of Heat.

Min. Aver. Max,
Class A, . A . 180 hae 144 coe 156
Class B, . m «185 Eee 148 rp 152
Class C, . ; . 134 ras 142 ae 153

TABLE X.—Middlesex Hospital.
Height of Head.

Min. Aver. Max.
Class A, . ‘ . 130 ti 140 tee 155
Class B, . ; aes by) el 138 Ke 148
Class C, . ‘ gre 85 | Ba! 131 ie 138
TABLE XI.—St Katherine’s School.
Height of Head.

Min. Aver. Max.
Class A, . ; Fires Wt ty 127 San 143
Class B, . ‘ oe rep 123 obs 130
Class C, . ‘ rere. bt 4 Nad 124 “ah 133

The next table shows the range and frequency of different
vertical diameters of Classes A, B, and C in the Middlesex
Hospital group, arranged in successive degrees of height; it

SIZE AND SHAPE OF THE HEAD, 343

will be seen that Class C is entirely confined to the four lowest
stages, Class A to the five upper, while Class B occupies the five
middle. :
TaBLE XII.—WMiddlesex Hospital.

Percentage Frequency,

Height in Millimetres. Class C. Class B, Class A.
150-155 dee ave moe ox hehe 3
145-149 ig mee + 11 this 13
140-144 Ee ea we 15 we 40
135-139 aaa 27 suid 43 +P 33
130-134 Yes 27 ane 22 ome 9
125--129 5 a 36 oe 6 &

120-124 sia | Meee ie ra a
The decimal points have, for the sake of simplicity, been omitted.

The next table gives the average horizontal circumference of
the head in millimetres for the three Classes A, B, and C in the
Middlesex Hospital and St Katherine’s School groups.

TaBLE XII1.—Average Cirewmference of Head.

Middlesex Hospital, St Katherine’s School,
Class A. Class B, Class C. Class A, Class B. Class C.
572 562 555 541 526 515

It will be observed that there is a progressive diminution
from A to C in both groups.

The two succeeding tables show the proportion that the cal-
culated brain-weight bears to the body-weight; the fraction
indicating this is obtained by dividing the calculated brain-
weight by the body-weight, and I shall refer to it as the
‘encephalo-somatic index.’ }

TABLE XIV.—Encephalo-somatic Index,

Middlesex Hospital. St Katherine’s School.
Min, Aver. Max. Min, Aver. Max.
Class A, 070182 0:0218 00288 | 0°0356 0°0465 0°0640
Class B, 0°0159 0°0203 070268 =| 0°03811 0°0409 0°0554

Class C, 070191 0°0200 0°0218 | 00350 0°0408 0°0521
1 This ratio may also be expressed in the following manner :—
1000 x Brain-weight
Body-weight
and the fraction thus got rid of, The meaning of the figures is, however, more

self-evident in the form stated above, and I have thought it best for this reason
to retain the fraction.

= Encephalo-somatic Index,

344 DR REGINALD J, GLADSTONE..

The rise in the average index in passing from Class C to
Class A is seen to be very considerable, and a so in
the case of the boys.

The three following tables show the cephalic indiaae of the
Middlesex Hospital and St Katherine’s School groups, and a
combination of these, which shows a slight tendency towards
dolichocephaly in Class A when compared with Classes B and C.
The higher cephalic indices ‘of these two classes are obviously
not due to the individuals composing them having actually
broader heads than those of Class A, as will be seen by
comparing these tables with the foregoing; but it is due to
the comparatively greater length of head in the individuals of

Class A.
TaBLE X V.—Cephalie Index.

Middlesex Hospital.
Min. Aver. Max.
Class A,’ «. ; . 706 te 77°4 ae 84°3
Class B, . ‘ <a Bob 78°4 Oy 85°8
Class C, . . 7103 eae oe Or 6 are 81°3

iere XVI.—Cephalie Index.

St Katherine’s School.
; Min. Aver. Max.
Class A, . i . 68°4 cee 77°0 aie 81°4
Chast. By od tengo. see ote gabe hs
Olean O;. 55854, eerie (TBE. ade ce ARB tu

TaBLE X VII.—Cephalic Index.
Middlesex Hospital and St Katherine’s School.

Min. Aver. Max.

Claw A. kn So OR
Class B, . ; Benes it be Wisse, ( o- | yy 83°6
Claes Os. ain 0 2 TET Plata TDi

Tables XVIII. and XIX. show the proportion that the height of
the head (from the biauricular line to the vertex) bears to its
horizontal circumference, the latter being expressed as 100. This
ratio I have termed the ‘ auriculo-bregmatic index, and use it in
place of the ‘length-height index,’ because the circumference
being proportional to both length and breadth, gives a better
indication of the general size of the head, taken in the
horizontal plane, than the length alone.

SIZE AND SHAPE OF THE HEAD. 345.

st6i: 100 x Height
it Circumference
~ On looking at the column containing the average indices in
the Middlesex Hospital group, it will be noticed that there is

= Auriculo-bregmatic Index.

_ a progressive increase from C to A, showing that there is not

only an absolute increase in the height of the head with an
increase in mental ability, but also an increase relative to the
other dimensions of the ‘head. This is not the case, however,
with the boys of St Katherine’s School, in which, although the
highest index occurs in Class A, and the lowest in Class C, the
average for Class C is above that of both A and B.

TaBLE XVIIL—Auriculo-bregmatic Index.

Middlesex Hospital.
Min. Aver..* .: Max.
Class A, « E 2 Oi <a 25°0 am 26°8
Class B, . ‘ 32 223 ‘a 24°2 che 27°5
Class C, . 7 ~ aL ces 23°6 ae 24°9

TABLE XIX.—Auriculo-bregmatic Index.

St Katherine’s School.
Min. Aver. Max.
Class A, .. . . 21°9 hi 28°7 =i 27°7
RR ER RR th MAF
Class C, . 5 . 20°9 ae 24:2 Ser 25°3

The last table, XX., shows the excess in millimetres of Class
A over Class C; which occurs in the three average diameters,
and in the two groups, viz., the Middlesex Hospital group as
representing adult measurements, and the St Katherine's School
the measurements in boys.

i

TABLE XX,
Average Measurements. Excess of
Class A. Class C. A over C.
Middlesex Hospital, Length, 199 193 6 mm.
St Katherine’s School, Breadth, 187 179 8 mm.
Middlesex Hospital, Length, 154 148 6 mm.
St Katherine’s School, Breadth, 144 142 2mm.
Middlesex Hospital, Length, 140 131 9 mm,
St Katherine’s School, Breadth, 127 124 3 mm.

The tables thus show a distinct correlation between large

346 SIZE AND SHAPE OF THE HEAD,

size of head and a high degree of mental ability, this correlation
being both absolute and relative to the general size and weight
of the body. In adults the increase in size of head appears
chiefly in the vertical diameter, which should always be
included in making any estimate of the size of the head; in the
boys the increase is chiefly in the longitudinal diameter, as has
been demonstrated also by Dr Alfred Binet in an article
entitled “ Etudes Préliminaires de Céphalométrie sur 59 Enfants
d@’Intelligence Inégale choisis dans les Ecoles Primaires de Paris,”
contained in L’ Année Psychologique, Septiéme Année, p. 369.

There are many other questions bearing upon this subject
which will well repay a farther investigation; such as the
relationship of nationality and heredity to the size and shape
of the head, and the connection of these with varying degrees
of mental ability; and in concluding this small contribution to
a large subject, I must express the hope, that I entertain, of
adding to these statistics with the view of confirming, or other-
wise, the results which I have already obtained, and of gaining
some fresh lights upon problems which are for the present still
obscure. I have also to thank the Rev. Mr J. B. Peile, Master
of St Katherine’s School, for his kind permission to measure
the boys, and the Managing Committee of the St Pancras Work-
house, and others who have helped me in this investigation,
and more especially Mr Freke Field, who has taken with great
exactitude the majority of the measurements, and borne a large
share in carrying out the statistical work.

ee

a 800. <
t- CK

Tt

‘THE FORM-RELATIONS OF THE DILATED CEREBRAL

VENTRICLES IN CHRONIC BRAIN ATROPHY.
By J. O. WAKELIN Barratt, M.D. Lond., F.R.C.S. Eng.

THE present paper is a continuation of investigations, already
published, on the form and relations of the normal cerebral
ventricles,! and on the form of the dilated ventricles met with
in chronic brain atrophy occurring in the insane. The relation
of the form of the dilated ventricles to the form of the brain
as a whole, and to some of its more important constituents as
studied in four cases, has now to be described.

Method.

Of the four brains whose ventricular cerebral cavity was
examined, the first (No. 1 in the table, p. 353) was removed at
the autopsy and placed in a saturated solution of potassium
bichromate, hardening being completed at the end of eight
months. In this fluid the brain at first floated, so that the
risk of changing the form of the brain during hardening was
inconsiderable. The remaining three brains were hardened
im siti by the injection of 10% formol solution into the
cerebral arteries prior to opening the skull. In all these cases
hardening of the cerebellum, pons, medulla, and base of the
cerebrum was complete, but the whole of the vertex had not
been reached by the injection, so that it was necessary to con- —
tinue the hardening process after removal; but the brain was
found to be so far hardened on removal, that it retained its
shape without change. The removal of the injected brain was
readily effected by sawing off the skull-cap close to the base of
the cranium.

Of these two modes of hardening, the first does not preserve
the form of the brain so faithfully as the latter, since the
support of fluid during hardening is not so perfect as that of
the skull. After the injection of formol, no doubt can be
entertained of the correctness of any slight obliquity or

1 Journ. of Anat, and Physiol., 1902, vol. xxxvi, pp. 106-126.

® Ibid., 1903, vol. xxxvii. pp. 150-167,

VOL. XXXVIIL, (N.S. VOL. XVII.)—JULY 1903. 24

a

348 DR J, 0, WAKELIN BARRATT,

asymmetry which is present. The injection of formol, however,
causes some swelling of the brain substance, and thus tends to

L R

Fic, 18.—Plan of the brain of Case 1, On the left is the upper surface of the
left hemisphere seen from above ; on the right is lower surface of the right
hemisphere also viewed from above, The plan of the cerebral ventricular
cavity is inserted in sitd, so that its relation to the cerebrum can be observed.
On the left side the fissure of Rolando, R, together with the ascending
frontal and intra-parietal fissures, are shown ; on the right side the anterior
limit of the right temporal lobe is seen, together with the optic chiasma,
the tuber cinereum, and the mesencephalon cut across at its junction with
the pons Varolii. This plan is made with reference to the horizontal plane
shown in fig. 14. Figs, 28, 3B, and 48 are constructed in the same way.

There is asymmetry of the lateral ventricles in respect of each other,
while the bodies of the lateral ventricles, together with the third ventricle,
are displaced to the left. The tips of the anterior cornua do not reach as
far forwards as the tips of the temporal lobes. The anterior cornua are
not disproportionately large as compared with the rest of the lateral
ventricles.

R, right; L, left,

This and the succeeding figures are one-half the natural size.

diminish the ventricular cavity, for which reason it is not
desirable to use a large quantity of injecting fluid; if the brain

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 349

is sufficiently hardened to retain its form, the completion of
the hardening may best be carried out after removal.

The hardening being completed, the plan of studying the
form-relations of the cerebral ventricles was similar to that
adopted in the previous work, A horizontal plane (Cp. figs,
1p, 28, 3B, 48) was marked out on the surface of the brain,
and then a series of equidistant frontal planes. Plans of the

L R

Fic. 28,—Plan of the brain of Case 2, seen from above as in fig. 1s. The same
asymmetry of the lateral ventricle is exhibited as in the preceding case,

brain, seen from above, below, and the sides, were then drawn
accurately to scale. The frontal sections, already marked out,
were then made and sketched. By means of the latter the
ventricles of the cerebrum were reconstructed, and a tracing
of the same inserted in each of the plans previously made.

Some practice is required before a sufficient degree of
accuracy is acquired to permit of an exact representation of
the ventricular cavity. In particular it is necessary to avoid

350 DR J. O. WAKELIN BARRATT.

perspective representations, and to construct. only plans and
side elevations. As some difference of opinion may exist as to
what should represent a horizontal plane in the case of the
brain, the latter is represented in the sketches by the horizontal
line in figs. 1 to 4, A, and the frontal planes referred to mare
were made at right angles to this plane.

Finally, the slices of brain were in each case put together

L R

Fic, 38.—Plan of the brain of Case 3, seen from above. As before, some
asymmetry of the lateral ventricles is present, chiefly in the posterior
cornua,

again, and a plaster of Paris cast of the cerebral ventricles made.

It was not possible in this procedure to secure perfectly accurate

apposition, nor, indeed, altogether to avoid distortion, so that

the cast had not the same valué as the reconstructed ventricular

cavity. Nevertheless it afforded a useful criterion of the
truthfulness of the reconstructed cavity, formed a check upon
accidental inaccuracies, and furnished much valuable information
in respect of details of form, while at the same time permitting

a ——— = CD =,

2

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 351

thicker slices of the brain (and therefore fewer in number) to
be made than would have been otherwise possible. A practical
detail may here be referred to. In dissecting out the plaster
east, fracture always occurs at the junction of the third and
one of the lateral ventricles. As soon, therefore, as the interval
corresponding to the septum lucidum is reached, this should
be filled up with plaster of Paris before any displacement of

L oe

Fic. 48.—Plan of the brain of Case 4, seen from above, Asymmetry is present
both in the form of the ventricles and in that of the brain. The cerebellum
and medulla appear displaced to the left of the middle line.

the fragments has occurred. In this way a cast is obtained

which is less fragile than would be the case if the lateral

ventricles were connected only to the third ventricle.

Form-relation.

The cerebral ventricular cavity may naturally be expected to

vary in relation to the general form of the brain, and more par-

352 DR J. O. WAKELIN BARRATT.

ticularly according as the head is broad or narrow. Thus, if the
brain of a dolichocephalic individual is compressed in its antero-
posterior diameter so as to change it towards the brachycephalic
type, the basi-bregmatic height remaining all the time unchanged,
the ventricular cavity would tend to become broader from side to
side; while if, on the contrary, the altitudinal index were simi-
larly increased, the cerebral lateral ventricles would tend to be-
come correspondingly arched from before backwards. The small
number of cases examined did not permit of any generalisation

R

Fie, 14.—Side elevation of the brain of Case 1. The fissure of Rolando, R,
together with the ascending frontal, the intra-parietal, parieto-occipital, PO,
and the calcarine fissures are shown, and an elevation of the third and right
lateral ventricles inserted in sitd. Note that the brain does not reach
vertically so high as the succeeding brains, and the lateral ventricle is
correspondingly flattened from above.

being made, and the divergences in type of the cases examined
were not considerable, the cephalic indices varying between 73°7
and 78:8, and the altitudinal indices between 68°3 and 79°0
(see table); but, as the sketches indicate, a conformity in the
relation of ventricular to cerebral form was found to exist in
the brains examined. Thus, in brains 2 and 4 (latitudinal indices,
73°7 and 75:0) the distance between the inferior cornua relatively
to the bodies of the lateral ventricles was greater than in brains
1 and 3 (latitudinal indices, 76°0 and 78°8); and again, the first
three brains, which had nearly the same altitudinal index (68°5,

_ DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 353

68°3, and 70 respectively), were more flattened, as seen in side
elevation, than brain 4 (altitudinal index, 79). To satisfactorily
establish such a relation, however, a large number of healthy

Table giving Particulars of the Brains Examined.

Weight _ Lati- Alti- | Brain:
No.| Mental State. Condition of | of | Ceebral | tudinal | tudinal | Cerebral
. Brain. inten tar Index. | Index. | Ventricles.

1 | Epilepticdementia) Wasted 1225.) 375c.c.) 76°0 | 68°5 |100:3°1

to

Senile dementia | Much wasted 1160,,| 47 ,,| 73°7 | 68°3 |100:4°3

3 | General paralysis | Wasted 1300,,| 97 ,,| 78°38 | 70°0 |100:7°5
os

General paralysis | Wasted 1220,,110 ,,| 75°0 | 79°0 |100:9°8

brains, presenting a greater variation of form than the few we
have had the opportunity of studying, require to be examined.
There is another factor, which determines the general form of

Fic, 2a.—Side elevation of the brain of Case 2, The brain is more arched above
than in the preceding case, and the ventricular dilatation is much greater.

The anterior cornu is relatively more enlarged than the rest of the lateral
ventricle,

354 , DR J. 0. WAKELIN BARRATT.

the dilated cerebral cavity, and that is the manner in which the
brain wastes. If the brain wasting associated with ventricular
dilatation were equally distributed, the increased size of the
ventricular cavity would in all cases present the same divergence
from the original type, increasing pari passu with the degree of
wasting. As a matter of fact, the wasting is unequal, and this

Fic, 3a,—Side elevation of the brain of Case 3. The vertex of this brain forms
a well-marked arch, and the dilatation of the ventricles, which is striking,
affects the anterior cornua and the bodies much more than the rest of the
lateral ventricles The width from above downwards of the third ventricle
is less than in the preceding figures. The middle commissure is absent.
The dilatation of the lateral ventricles is far greater than that of the third
ventricle. The fissure of Rolando, R, is less simple than in the other brains
represented,

disturbs the relation between the form of the dilated and that
of the original cavity, by causing disproportionate local increase
in size, which is the more marked the greater the brain atrophy.
Thus, in all the cases examined, the wasting had affected the
frontal and parietal lobes more than the rest of the brain
mantle, the difference being especially noticeable in the general
paralytic brains 3 and 4, and correspondingly influencing, as a
glance at the figures shows, the shape of the anterior cornua
and bodies of the lateral ventricles, which had undergone a far

See: mC mh

a

DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 355

greater relative increase than the rest of the ventricular cavity.

Here again it may be observed that in brain atrophy of the
insane the dilatation of the lateral ventricles, which, in its way,
forms the negative of the corresponding wasting of the brain
mantle, is, as is well known, very considerable relatively to that
of the third ventricle, embedded in the thalamencephalon, which
undergoes little alteration in size.

Other points in connection with the general relation between

Fic. 4a. —Side elevation of the brain of Case 4. Considerable dilatation of the
cerebral ventricles exists, and the lateral ventricles are much more arched
than in any of the preceding illustrations. The dilatation affects
principally the anterior cornua aud bodies of the lateral ventricles.

ventricular form and cerebral form naturally suggest themselves
as the sketches are studied, but it is perhaps better, as the num-
ber of cases before us is so small, to defer further speculation
until a large series of brains has been investigated, and to remain
for the present content with merely putting on record, as far
as possible graphically, the conditions present in the cases now
under consideration.

In passing to study details of form-relation, we naturally turn
first to the fissures of the brain as presumably standing in a
constant position in respect of the ventricular cavity. But at
the outset it becomes clear that the smaller fissures are too

356 DR J. O. WAKELIN BARRATT.

variable to be of much value in forming landmarks in respect
of ventricular dilatation, and the same difficulty also arises in a
lesser degree in respect of the main fissures—namely, the fissures
of Sylvius and Rolando and the parieto-occipital sulci. Sherring-
ton and Griinbaum,! in the case of the motor area, have shown
that the fissures do not correspond to motor centres, and there-
fore afford but limited assistance in localisation—all this being
in striking contrast to the far greater constancy and symmetry
of bilateral situation of these centres. The same is presumably
true of the relation in respect of function of the sulci of the
brain mantle elsewhere. And as variations in the manner of
folding of the brain mantle may be supposed to influence within
certain limits the form of the normal ventricular cavity, so the
same circumstance may also cause variations in the trace of the
fissures (of Rolando, parieto-occipital, etc.) in respect of the
ventricular cavity as exhibited in a plan or side elevation of the
brain. Moreover,the further difficulty arises that when a fissure—
for example, the fissure of Rolando—is mentioned, merely the
base of the fissure as it appears on the surface is usually referred
to, and the sulcus in its depth is left out of consideration. As the
former is not necessarily a faithful index of the latter, it is
obvious that the base of the sulcus is not of great value in
respect of the determination of the form-relation of the ven-
tricular cavity. Nor does it seem possible to obtain much
greater accuracy by attempting to simplify the trace of the
fissure of Rolando by representing it as a single line whose
direction may be taken to indicate the mean position of the
sulcus in its depth, for such a line could hardly be determined
with sufficient accuracy to be of value when the fissure of
Rolando is complicated in character as in fig. 3B.

Bearing in mind that the fissures of the brain are within
certain limits variable, and that their relationship therefore to
the cerebral ventricles is not one of precision, we may now
briefly refer to this relationship so far as it concerns, in the
brains studied, the main fissures—namely, those of Rolando and
Sylvius (posterior limb) and the internal parieto-occipital suleus
—the position of which is exhibited in the figures.

1 Brit. Med. Jowr., 1901, ii. p. 1858. Cp. also Schafer, Festschrift zu Kart
Ludwig, 1887, Leipzig.

I

DILATED GEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY. 357

In its general direction in side elevation the fissure of Rolando,
as a glance at the figures will show, was found to run from or
near the junction of the third and lateral ventricles upwards and
backwards to a point a little behind the middle of the vertex, only
the lower half to third lying over the middle of the body of the
lateral ventricle; while in the plan this fissure lay more
posteriorly and nearer the middle line over the body at its.
junction with the posterior cornu, and also over the inferior cornu.

The posterior limb of the fissure of Sylvius in its middle third
corresponds approximately to the upper border of the third
ventricle, but the correspondence exhibited some variation, as.
the figures show.

The internal parieto-occipital and calcarine fissures come into-
relation with the posterior cornua, especially when these are pro-
longed some distance backwards into the occipital lobes. In the
brains examined, however, the posterior cornua were short, and
lay in side elevation opposite the junction of these two figures.

In addition to an acquaintance with the arrangement of the
main sulci in regard to the ventricles, a knowledge of the
position of the ventricular cavity in respect of the main out-
lines of the brain is of great assistance in enabling a mental
picture of this cavity to be formed in a brain which is viewed
from without. A few of these relations exhibited by the figures.
may be here referred to.

‘The anterior cornua reached approximately as far forwards.
as the tips of the temporal lobes when the dilatation was small
(ep. fig. 1, A, B), and, as the dilatation increased, the anterior
cornua came to lie in front of the tips of the temporal lobes (as.
in figs. 2 to 4, A,B). In the figures the anterior cornua are seen
to reach to a distance from the tips of the frontal lobes, which
amounts in each case respectively to 22%, 18%, 12%, and 20%
of the antero-posterior diameter of the brain. Further data of
the same kind may be determined, if desired, by the help of
the figures which represent the actual distances! apart from the
various structures exhibited in plan or elevation, in conjunction,
if necessary, with the measurements given in the table.

The inferior cornua corresponded in side elevation very
nearly to the middle third of the second temporal convolution,

1 Reduced to one-half in reproduction.

358 DILATED CEREBRAL VENTRICLES IN CHRONIC BRAIN ATROPHY.

or lay slightly below this portion of the gyrus. The anterior
limit of the inferior cornu was represented in plan by the
posterior border of the optic chiasma, or lay somewhat behind
this level. The position of the inferior cornua, seen in plan, in
respect of the temporal lobes, is better ascertained by reference
to the figures than from a description in words.

The posterior cornua, as is well known, vary so widely in
different brains as to their form and the extent to which they
pass backwards into the occipital lobes, that each individual
case requires a separate description, and no generalisation seems
possible. In the four cases examined they were very short.

The anterior limit of the junction of the body and inferior
horn of the lateral ventricle lay in or slightly behind a frontal
vertical plane passing through decussation of the anterior
pyramids in the medulla, and passing above, through, or a little
in front of the superior extremities of the Rolandic fissures. In
plan the inner border of the body was found to lie close to the
middle line or even to pass a little distance to the distal side of
the middle line, while the outer border lay approximately
midway between the mesial plane and the outer margin of the
brain; but its curvature varied in the different brains, and the
extent to which it passed outwards was greatest in Case 4, in»
which the degree of atrophy was also most marked.

As regards the third ventricle, in plan the tip of the preoptic
recess corresponds to the anterior border of the optic commis-
sure. The supra-pineal recess was found to be so variable that
its position required separate description in each individual case.
The upper end of the aqueduct of Sylvius, however, was more
constant in position. It Jay in the brains studied nearly
vertically above the decussation of the anterior pyramids of the
medulla oblongata. In brains 3 and 4 no middle commissure
was present.

The foregoing observations, which were undertaken in the
course of an investigation of chronic brain atrophy in the insane,
are of necessity fragmentary in character as they are also
limited in number. It is hoped that the data herein contained
may be of use as a record of the relative form of the dilated
cerebral ventricles in respect of the atrophied brains in which
they exist.

ABNORMALITIES IN THE SACRAL AND LUMBAR
VERTEBR OF THE SKELETONS OF AUSTRALIAN
ABORIGINES. By Dr W. Ramsay Smiru, Adelaide, S_A.

THE sacrum, No. 866, from a female aboriginal, consists of five
pieces. The sacral canal is open posteriorly for its whole
length, and passes to the left of the spinous process of the third,
and to the right of the spinous process of the fourth and fifth
vertebre. It divides the spimous processes of the others.

On the left side, the alar portion of the first vertebra passes
upwards and forms a synchondrosis with the enlarged costal

process of the fifth lumbar. This synchondrosis passes
outwards, dividing the auricular surface into two portions—a
sacral and a lumbar.

The fifth lumbar vertebra has its body thicker on the left
than on the right side; and its arch is incomplete posteriorly.
It will be evident that this vertebra partakes of the characters
of a sacral vertebra on its left side, and of a lumbar vertebra on
its right.

The fourth lumbar vertebra presents an abnormality on its

360 DR W. RAMSAY SMITH.

right side; the transverse process springs from the side of the
body in front of the pedicle, and with no connection either with
it or the superior articular process (see figure).

The sacrum numbered 872 is composed of six normal pieces,
‘The one numbered 873 is composed of the typical number, five,
I have examined an aboriginal specimen with four,

A sacrum, No. 842, in which the body of the first vertebra
was not ossified to that of the second: the spine is bifid, the
inferior articular processes are free and not fused with the
superior of the second, the right lateral mass is completely
fused with that of the second, the left lateral mass is fused
only at its tip.

These specimens are specially interesting as forming a
graduated series in Australian aboriginals from four normal
pieces, which is not uncommon, through four and a half, five,
five and a half, to six normal pieces. ‘They illustrate the
transitional characters at the junction of the lumbar and sacral
regions,

Recently, on examining a mounted skeleton belonging to Dr
R, S. Rogers of Adelaide, [ observed an abnormality which he
had not noticed, and which he has permitted me to describe.

The skeleton was an imported one, made up, evidently, of the
bones of white subjects, but of such a ‘composite’ character
that one could not say with any degree of certainty what
parts belonged to males, and what to females, The sacrum
was of normal size, but the antero-posterior curve was much
exaggerated, |

The sacrum, which is fused into one bony mass with the
coecyx, is formed of five sacral vertebre,

On the left side, the first sacral vertebra has its alar portion
only slightly developed: and this portion passes upwards and
backwards to form a synchondrosis with the more truly alar
border of the sacrum, which is formed by the second vertebra.
In this instance the synchondrosis passes so much upwards,
that the costal process of the first vertebra is cut off from
articulating with the ilium,

The first vertebra has two distinct articulations with the
second. The third has an abnormally large spinous process.
The spinal canal is open dorsally in its lower part.

e pate surface the sacrum presents an extra foramen

side on the second pda between the first and
min ;

somewhat vetnaceabila that all these specimens of

nerar serps of the sacrum should be on the

umbers refer to specimens presented by Dr Ramsay
to the Anatomical Museum of the University of

RUDIMENTARY CONDITION OF THE CAROTID CANAL.
By G. H. K. Macauisrer, B.A., St John’s College, Cambridge.

THE following peculiarities were observed in the skull of a
male negro from Jamaica presented by Dr C. A. H. Thomson
of Christ’s College to the Anatomical Museum at Cambridge.
The right side is normal, but the left side shows in its petrous
region certain abnormalities associated with an anomalous
carotid canal.

The jugular foramen is normal: its anterior border is coronal
and has rather a sharp edge; its mesial border is situated
lateralwise to the anterior condylar foramen. The region
which is especially anomalous is situated anteriorly to the ~
jugular foramen ; its lateral boundary is formed by the ragged
edge of the tympanic bone, and its mesial boundary is the
basilar process of the occipital. The ‘carotid lobe’ of the
petrous bone, which normally wraps around the carotid canal
on its outer wall, is here a more or less quadrilateral plate, with
a rough surface.

Along its mesial margin the bone is flattened. This flattened
area forms a channel whose banks are formed by the mesial
border of the remainder of the petrous bone laterally, and by
the lateral edge of the basilar plate mesially. This channel
continues backward, crosses the petro-occipital suture, and
comes into relation with the mesial border of the jugular
foramen; it terminates at the anterior condylar foramen.
Continuing forwards, the channel leads to a tunnel which, running
between the apical region of the petrous portion of the
temporal bone and the great wing of the sphenoid, opens into
the middle fossa of the cranial cavity. From this a small
groove passes forwards between the lingula and the body of the
sphenoid to the anterior clinoid process. It then passes over
a solid formation, which corresponds to the united anterior
clinoid process and olivary eminence—for, while in a normal
sphenoid the carotid groove is sufficiently big to establish the
independence of these two named processes, the minute
substitute for the groove observed in this specimen is a mere
trace on a solid bar of bone.

RUDIMENTARY CONDITION OF THE CAROTID CANAL. 363

In the middle fossa the tunnel is separated from the hole
for the petrosal nerves by a portion of the lingula, which
projects backwards and meets the petrous portion of the
temporal bone.

The petrosal portion of the channel described is 18 mm. in
length and 4 mm. in width. The tunnel is 3 mm. in diameter.

At the postero-lateral angle of the rough area described above
as the carotid lobe of the petrous portion of the temporal bone
is a foramen 0°7 mm. in diameter, which is probably the
representative of the carotid foramen. From this a tortuous
canal runs first upwards and backwards, then forwards and
inwards, coursing through the very midst of the cancellous
structure of the petrous element towards its apex, where the
canal opens a little below the point where a normal carotid
canal should open. This minute canal is at first circular in
lumen, but becomes slit-like towards the apex. It is 31 mm.
in length, and in its circular portion is 0°7 to 0° mm. in
diameter.

'

VOL. XXXVIL (N.S. VOL. XVII.)—JULY 1993. 25

SOME PECULIAR FEATURES IN A TEMPORAL BONE.
By P. P. Laipiaw, St John’s College, Cambridge.

A TEMPORAL bone presenting several unusual characteristics
has been found in the collection of Egyptian bones in Cambridge
University Museum.

The bone is of Egyptian origin in a good state of preservation,
and has small portions of the sphenoid and occipital synostosed
with it but the rest of the skull is lost. The part of the
sphenoid in question includes the spine and foramen spinosum,

View of specimen from below.—(i) Absence of stylo-mastoid foramen,
large size of mastoid foramen. Styloid and zygomatic processes
are broken, Note the shallowness of the digastric groove.

while the occipital portion, though larger, presents no feature
worthy of notice: its extent and shape may be seen in the
accompanying drawing. It belongs to the left side.
The peculiar features are :—
(1) Absence of the internal auditory meatus and of the
stylo-mastoid foramen.
(2) Absence of the jugular fossa, and partial absence of the

SOME PECULIAR FEATURES IN A TEMPORAL BONE. 365

lateral sinus-groove in the interior, with presence
of a large mastoid foramen.

On the posterior intracranial face of the petrous bone’ the
internal auditory meatus is absent, a minute hole being observ-
able in the place where the large canal usually opens. This,
on probing with a bristle, seemed to be occluded, and might be
due to imperfect preservation of the inner table, as there are
one or two other such imperfections in other parts, a rather
more prominent set of holes being found on the surface of the
tegmen tympani. Correlated with the absence of the internal

View of specimen from behind and above.

meatus is the absence of a stylo-mastoid foramen, and I was
unable to find any foramen in the vicinity through which the
facial nerve could have made its exit from the skull. As far as
I know, absence of the internal meatus has not been met with
hitherto,

The second peculiar feature is that the groove for the lateral
sinus ends at the mastoid foramen, all the blood being evidently
drained by this canal. The sigmoid groove of the lateral
sinus is somewhat smaller than usual, and the foramen larger
than normal. The superior petrosal sinus-groove is present in
its normal form, but the inferior is absent.

366 MR P. P. LAIDLAW.

One would expect that the absence of any internal auditory
meatus, and therefore presumably absence of the VIII. and VIL.
nerves, would have so affected the development of the internal
ear as to render it obviously imperfect. Such, however, is not the
case in this instance, as the bony parts were well developed and,
compared with a European bone taken at random, of large size.

Thus, such points as hiatus Fallopii, canal of Eustachian tube,
and tensor tympani were apparently the same as usual, while
the aqueductus cochlee and aqueductus vestibuli were both
easily identified.

Also such points as the j/enestre rotunda et ovalis of the
internal wall of the tympanum could be identified by reflecting
light down the external auditory meatus. In short, it otherwise
presented perfectly normal features.

I append some measurements to compare with an ordinary
well-developed temporal bone.

Egyptian bone. European. .
From the tip of petrous bone to internal surface of
skull-wall along the line of the superior petrosal
sinus, . ; 61 mm, 60 mm.
From the same paint in the ianeeiar of the ‘aku to
the apex of the angle occupied by the bes ss

of the sphenoid, . : : 49 mm, 46 mm.
From the apex of angle in last sshinicoentit to the
tip of the petrous bone, . ; 26 mm. 25 mm.

These give an anterior triangle, which expresses to a certain
extent the development of the petrous bone and internal ear.

Egyptian bone. European.
From tip of petrous bone to the angle occupied by

the jugular process of the occipital, . : 30 mm. 34 mm.
From internal surface of skull to where superior
petrosal sinus meets it, ‘ : . 46 mm, 35 mm,

Lastly, the vertical depth from the surface of the eminence
of the superior semicircular canal to the base of the styloid
process was 23 mm. in the Egyptian and 25 mm. in the
European.

These figures do not indicate any imperfect development of
the Egyptian specimen.

The specimen, on being sawn open, was seen to present a
completely developed bony labyrinth, as all parts were present

SOME PECULIAR FEATURES IN A TEMPORAL BONE. 367

as far as could be seen—vestibule, semicircular canals, and
cochlea. 3

The cribriform area at the fovea hemispherica was easily
made out with the aid of a lens. The small aperture mentioned
above, which existed in the place of the internal auditory
meatus, proved to be a very imperfect aqueduct of Fallopius,
which, however, could not be traced far ; moreover, the arrange-
ment of the cancelli and lamelle of the bone occupying the
area usually taken up by the meatus showed that the con-
dition could not be regarded as pathological.

NOTES ON A CASE OF FEATHER-BIFURCATION.
By W. J. RutHerrurD, University of Glasgow.

FEATHERS, in common with other structures, are at times liable
to show abnormal characters, the reasons for which can at
most be only imperfectly understood. Feathers of birds, teeth
of mammals, etc., and many other structures, as is well known,
are all produced as epidermal growths having some connection
with a mesoblastic papilla at the base of a follicle which is
sometimes only secondarily formed.

Probably all such structures which are in connection with a
single papilla or follicle have been observed at one time or
another to present the condition of Dichotomy or, more generally
speaking, of ‘ bifurcation’ as an abnormality.

It would seem that, as the tooth is the structure whose well-
being or the reverse impresses itself upon the individual the
most, dichotomised teeth have had more attention paid to them
than have cases of dichotomy in other analogous organs. This
is only natural, since so many isolated specimens must pass
under the observation of dentists every day.

Bifurcated or ‘double’ feathers have, however, been noted on
several occasions, and if we knew where to look for recorded
instances of the abnormality, quite a large amount of informa-
tion might be collected in reference to this subject.

I have had in my possession since the spring of 1901 a
domestic pigeon which has in every ‘crop’ of feathers presented
two bifurcated rectrices—the feather nearest to the middle line
on each side of the tail. When I first saw the bird, it was not
many weeks old, and it then had the two bifurcated feathers
in exactly the same place in which they have always been
presented—they being the same two follicles which constantly
give rise to this abnormal type of feather. I think it worth
while mentioning this particularly, because many ornithologists
lay great stress on the constant difference between the first

1] have noticed that Bland Sutton mentions,‘ dichotomised feathers’ in his
Evolution and Disease (Contemporary Science Series, No, v.), [1890]; and Gadow,
in Newton’s Dictionary of Birds, part iii, p. 587 (1890), mentions ‘double
feathers,’ but without giving any information on the abnormality.

NOTES ON A CASE OF FEATHER-BIFURCATION. 369

plumage, or nessoptiles of a young bird and that which it
subsequently acquires; and, considering how they are apparently
justified in drawing this distinction, it seems at first sight

Te,”

Fic. 1.—The two median rectrices of a ‘domestic pigeon’ showing dichotomy.
1. Feather to right of middle line seen from right side (¢) and above—
a, ‘barrel’; a’, secondary shaft. 2. Feather to left of middle line
(second type) seen from lower surface —}, ‘barrel’ ; b’, secondary shaft ;
* Indicates where some of the filaments of the web are fused, forming a
solid mass,

remarkable that an abnormality present in the nest-feathers
of a bird should be reproduced feather for feather in after-life,
while the colouring of the feather is, as I have noticed, hy no

370 MR W. J. RUTHERFURD.

means consistently adhered to from year to year even in such
birds as the pigeon, whose feather-pigmentation has been, as one
might say, standardised in the course of many generations even
in the case of the common or garden sorts about whose ‘ points’
no care at all is taken.

It will be noticed from the accompanying sketch that the
bifurcation is by no means equal in the two abnormal feathers
of the same year, and I may mention that the feathers which
grew at the end of the summer of 1902 are those which I have
figured here. The bifurcated portion of each feather shows
four ‘webs’ instead of the normal two, and in this, as in other
respects, the feathers merit the title of ‘double feathers,’ The
additional webs in apposition to one another are pointing up-
wards to meet at an angle like the sloping ridges of a roof, and
are much worn and somewhat irregular in outline from their
constant mutual friction. The separate filaments of which
these webs are formed are stiff and bristle-like, though bearing
the ordinary barbules as might be expected; distally, however,
they are quite normal, and have only been affected by friction
to a very slight degree. Some of these filaments of the
additional or secondarily formed webs, just in the angle between
the two ‘secondary shafts, as I will call them, where they
come off from the main shaft, are exceedingly small and incon-
spicuous ; while others (some on that secondary shaft which was
nearer to the middle line, others on that which was more
remote) are unusually long and thick (I have measured several
which are 14 to 17 millimetres in length) and these again
may have small secondary filaments coming off from them at
a slight angle.

In this year (.e., 1902) the bifurcated feathers were of two
distinct types: the one, which grew to the right of the middle
line, had its shaft (using this word in its limited meaning of
the part of the ‘quill’ which has a web coming from either
side—right and left—of it) doubled in practically the whole
of its length, the only part of the ‘shaft’ common to both
the secondary shafts being one centimetre long; while the
other—from the left side of the middle line—has a commor

shaft 46 millimetres in length, each of its secondary shafts being
62 millimetres long.

NOTES ON .A CASE! OF FEATHER-BIFURCATION. 371
The secondary shafts of the more markedly double of the
two feathers under consideration have the following lengths :—

that nearer the middle line 107 mm.,

that farther off from the middle line barely 109 mm. ;
there being thus a difference of not 2 millimetres between
the two

a difference so small that it may be quite neglected.

Fie. 2.

It will thus be seen that the only difference between the
two feathers, the total lengths of whose shafts are practically
the same (12 cm. in the one case, and 11 cm. in the other), is
the degree to which the dichotomy has been carried out, and
this degree varies slightly, not only in the different feathers
(from opposite sides of the mid-line, that is to say), but also
in the same feather in different years (of course this means
feathers from the same relative situation in the line of the
rectrices, the amount of dichotomy to be seen in any two
feathers from the same feather-follicle not being the same).

On cutting the shaft of the more markedly dichotomised of

iN
CL

at

Fic. 3.—Transverse section of common portion of shaft, showing its internal
aspect, and bifurcation into the two secondary shafts,

the two feathers across at the place where it is supposed to
become metamorphosed into the barrel, and looking up it

372 MR W. J. RUTHERFURD.

towards the free end of the feather, a distinct view was obtained
of the double lumen, where the two secondary shafts came off
from the main or parent stem.

I particularly noticed that the two dichotomised feathers.
which grew in the room of those which had just moulted towards.
the end of August of 1901 (this was the second crop of feathers,
or the first crop of teleoptiles), were much less markedly
dichotomised than either before or since, the dichotomy only
extending for about 5 centimetres or even less from the
distal extremity of each of the two feathers under considera-
tion.

At this time I happened to notice in the case of one of these
feathers a condition which I then thought offered a clue to the
whole condition. The abnormal feather situated on the right
side of the body was, during its growth till the entire feather
was between about 4 or 5 centimetres long, soaked and
discoloured with blood and pus. A little reflection, however,
soon convinced me that this condition was only the effect, and
not the cause, of the dichotomy, and could not be expected to
occur with each of the feathers every time a dichotomised one
was in the process of development and growth. The reason of
the sepsis was probably as follows :—The feather-follicle was no
doubt normal in size, and with a lumen only adapted for the
passage of a normally sized feather; it would consequently
become injured (as was indicated by the blood-stains) by the
passage of what was, for this purpose, practically two feathers,
and a micro-organism would subsequently gain admittance to
she abraded surface.

I have satisfied myself that the abnormality does not in this
instance arise from the fusion of two of the growing rectrices
because of over-crowding or any other cause, by the simple
procedure of counting the number of rectrices. For the
domestic pigeon, and, in fact, for all the Columbide, this number
is twelve, and by counting each abnormal feather as a single one,
I arrive at that number for this bird, which has thus the
normal number of tail-feathers.

The reason of the abnormality is at present quite unknown
to me, with the exception that in all probability it is not due to
domestication. It is very easy to put all departures from the

>
sa tds

a

NOTES ON A CASE OF FEATHER-BIFURCATION. 373

normal down to ‘the evil effects of domestication, as it is the
modern tendency to do; but it is just a lazy man’s trick, unless
the procedure can be proved up to the hilt, which is seldom
possible. As Gadow says, “monstrosities are naturally more
observed in domesticated than in wild birds”;! but it must be
borne in mind that the effect of domestication is, by bringing
the domesticated animal more into contact with man, just to
make every little departure from the normal the easier of
observation and of perpetuation, while in the natural condition
every such departure has enormous odds in the favour of it not
being noted by anyone, and of being in subsequent generations
swamped by the succeeding increments of normal blood. This
is a fact that some modern theorisers would do well to
remember. Canon Tristram has kindly informed me that he
has noticed a similar case of bifurcated feathers on the skin of
a foreign hawk: the abnormalities are similar in each case,
though in the one instance the bird is domesticated, while in
the other case the bird was what is (for some unknown reason)
ealled ‘ wild.’

Tt would have been interesting in many ways if I could have
obtained young birds descended either from this bird or from
its blood relations, but, unhappily, the bird itself seems to be
quite sterile, and the stock from which I obtained this individual
has subsequently been dispersed.”

1 Loe. cit.; the italics are mine.

2 It would be well here to quote in full a passage from Darwin’s Variation of
Animals and Plants under Domestication, where, although his meaning is not as
clearly worded as might be desired, he refers to a similar condition. He writes:
“ With respect to the primary wing-feathers, the number in the Colwmbide#, as
far as I can find out, is always nine or ten. In the Rock-pigeon it is ten ; but I
have seen no less than eight short-faced Tumblers with only nine primaries, and
the occurrence of this number has been noticed by fanciers, owing to ten flight-
feathers of a white colour being one of the points in short-faced Baldhead-
Tumblers, Mr Brent, however, had an Air-Tumbler (not short-faced) which had
in both wings eleven primaries. Mr Corker, the eminent breeder of prize carriers,
assures me that some of his birds had eleven primaries in both wings. I have
seen eleven in one wing in two Ponters. I have been assured by three fanciers
that they have seen twelve in Scanderoons ; but as Newmeister asserts that in
the allied Florence Runt the middle flight-feather is often double, the number
twelve may have been caused by two of the ten primaries having each two shafts
to a single feather” (vol. i. p. 159). It will be noticed that this explanation
offered by Darwin is only a supposition of his own, and it would be interesting to
learn whether it was correct or not.

374 NOTES ON A CASE OF FEATHER-BIFURCATION.

I do not know that, in the present state of my knowledge on
this subject, it is permissible for me to draw any deductions on
the subject of the number and even the arrangement of feathers,
but since Darwin gave an explanation for the presence of extra
wing-feathers in certain pigeons, I think that a similar explanation
might be advanced for the enormous number of additional
rectrices present in many fantails'—that the extra number was
arrived at by the successive differentiation of single rectrices into
several complete feathers, or even into groups of feathers? This
might even be applied to those aberrant members of the
Columbide, where the number of rectrices is more than
normal.

Darwin also mentions, in connection with those pigeons
with excess of rectrices, that the uropygial gland is aborted
in many instances.® I will endeavour, if my bird by any
mischance should happen to die while I am still interested in
this subject, to investigate by sections the state both of its oil-
gland and of the papille and follicles from which the abnormal
feathers ‘are wont’ to arise. It strikes me as being somewhat
curious that in the Colwmbide the absence of the uropygial
gland should be connected with an increase in the number of
the rectrices, when the same absence is found conjointly with an
aborted state of the rectrices in certain ‘tail-less’ fowls.

I may find that the dichotomy is due to a compound papilla
upon which the feather rests. Such compound papille are given
the credit of causing the tubercles normally found upon tri-
tuberculate as well as upon multituberculate teeth, and will,
perhaps, be used to explain the abnormal condition shown by
dichotomised or bifurcated feathers (I give a choice of terms, so
that, if the first happens to be open to criticism, the second may
escape).

1 Loe, cit., pp. 146-7, 161-2, ete.

° This opens up a tempting field for speculating on the origin of pteryle, ete.
especially when taken in connection with recent investigations on hair-grouping in

relation to reptilian scales,
> Loe. cit,

a a a oe ~

ON THE OCCURRENCE OF A ‘PRINCIPAL ISLET’ IN
THE PANCREAS OF TELEOSTEIL (Preliminary Note.)
By Joun RENNIE, B.Sc., University Assistant in Zoology,
Aberdeen.

Our knowledge of the existence of islets of epithelial cells
in the pancreas of fishes is of comparatively recent date
(Laguesse, ’95; Massari and Diamare, ’98), and has hitherto
been limited to a relatively small number of species. In an
account of work soon to be published I describe them in. all
the leading divisions of Teleostei, where they are shown to occur
with such frequency that one may now conclude they constitute
a common anatomical character of that group. In this investi-
gation some facts of interest have emerged, one of which is the
subject of the present note.

As the result of the examination of large numbers of
specimens, I have noted in various species the constant occur-
rence in a definite position of a particular islet. Of the islets
present, as far as my observation goes, this one is invariably the
largest, and its position in the different species in which I have
found it is so similar, that I am of opinion it is to be regarded as
the same organ in all cases. Since I have not been able to
discover (with one possible exception noted below) the same
constancy in the case of the other islets, and since it is quite
evidently the most important of these formations, I have termed
it the ‘principal islet’ Owing to the extremely diffuse con-
dition of the pancreas in most Teleostei, these islets, possessing
greater opacity, may usually be observed by the naked eye.
They differ somewhat in form, but I have always found the
principal one rounded or oval in section and enclosed within
a more or less definite capsule. In Pholis gunnellus, the species
of perhaps smallest adult size in which I have noted its existence,
its longest diameter is about 15 mm.; while in large Cyelopterus
or Lophius it may reach 14 mm. in length and 5 mm. in thick-
ness.

The following is a list of the species in which I have observed
it, viz.:—Zeus faber, Lophius piscatorius, Cyclopterus luwmpus,
Pholis gunnellus, Zoarces viviparus, Anarrhichas lupus, Chiro-

376 MR JOHN RENNIE.

lophis galerita, Hippoglossus vulgaris, Plewronectes platessa,
Synynathus acus, Nerophis cquoreus, Syphonostoma typhle.
Besides these I have further noted in several Gadidew and
other Plewronectide a structure similar in appearance, which
is probably this islet, but I have not yet been able to verify
its constancy nor to examine it histologically.

In Zeus, Plewronectes, and Hippoglossus the principal islet
is attached to the base or side of the gall-bladder. In the
first two it is more or less completely enveloped by zymogenous
tissue, in Hippoglossus the latter is almost absent. In this
position Diamare has noted the occurrence of a large islet in
Orthagoriscus mole and in Rhombus levis, but makes no obser-
vations on their constancy. In the other species which I have

sp. Md.

pris.

Principal Islet in Pholis gunnellus. 1., liver; sp., spleen ; m.a., mesenteric artery ;

he.a., hepatic artery ; po.v., portal vein ; pr.és., principal islet.

named it may be stated generally that this islet is placed on
the ventral side of the mesenteric artery and near to it, in the
region of the abdominal cavity anterior to the spleen. In the
forthcoming communication already referred to I shall indicate
its exact position in each case; at present I shall limit myself
to a statement of its relations in Pholis gunnellus. This species,
though small, is one in which it may very readily be found.
If the abdominal cavity be laid open by removing the right

wall and the specimen pinned to a dissecting tray under water,

the viscera may then be drawn towards the ventral side of the
fish. If this be done, the leading blood-vessels, owing to their
walls being pigmented, may easily be followed. A short
distance in front of the spleen the mesenteric and hepatic
arteries, together with the portal vein, enclose quite a small

a ee), ee ee a —_
Pa —_
‘5 . ——
—- ee
“dd > ———— 2
as

‘PRINCIPAL ISLET’ IN THE PANCREAS OF TELEOSTEI 377

triangular area, within which lies the islet in question. It is
enclosed in a fairly tough capsule, which is frequently quite
black owing to the deposition of pigment. (See figure.) Histo-
logically it possesses the same structure as other islets in the
same and other fishes, and no doubt can be entertained as to
its homology. The authors cited have come to the same
conclusion regarding similar formations seen by them. Before
becoming acquainted with their work, I had satisfied myself
as to this, their true nature; my evidence will appear in my
next communication.

Regarding the question of function much has already been
_ written on the subject, mainly with regard to the higher verte-
brates. Latterly the consensus of opinion inclines to the view
of an internal secretion, and with this view my observations are
in complete accordance. The opinion of Laguesse, that they
represent a stage to which the zymogenous elements may revert
for a time, the tissue alternating throughout life between the
epithelial and zymogenous conditions, does not agree with the
facts in those fishes in which this particular islet-—apart from
others—is to be found at all times. It is a permanent organ,
and I hope to show from experiments at present in progress, as
well as from internal histological evidence, that it is functionally
active.
- I have further given some attention to the question of a
possible similar constancy of occurrence in the case of the other
islets. For this purpose I have examined several hundreds of
Lophius piscatorius and a smaller number of Hippoglossus vul-
garis (about fifty). In both of these I selected a small area of
pancreas close to the pylorus. Within this area in Lophius
there are situated several islets—a varying number, I am
inclined to think. With very great regularity there occurs one
which is markedly larger than the others. It is always next in
size to the principal islet. I think it probable that more careful
observation will show that it occurs with the same constancy as
the principal. In Hippoglossus the area contained one large
visible islet. It and the principal were the only two I could
find by dissection in this species. In every case, save one or
two, it was found. Whether the failure to find it in those few
cases was due to want of skill on the part of the investigator

378 ‘PRINCIPAL ISLET’ IN THE PANCREAS OF TELEOSTEL.

will be revealed by more extended enquiries. I incline to the
view that it also is a structure constant in occurrence, Wits
definite anatomical relations. .

Further, I have found an islet, large enough to be seen by the
unaided eye, within this area, in Anarrhichas, Pholis, and
Pleuronectes; I have not yet had opportunities for observing
whether it occurs regularly or not.

If constant and variable islets can be proved to exist, the
relation between the two, I suggest, is probably similar to that
between the thyroid and accessory thyroids, or spleen and
accessory spleen. If this is so, since no constancy of the nature
[ describe has, so far as I know, been found amongst higher
vertebrates, it may be that in the course of phylogeny the
principal islets have disappeared, while the accessory have
increased in number and importance.

REFERENCES.

(1) Lacussse, E., “Sur la formation des ilots de Langerhans dans
le pancréas,” C. R. Soe. Biol., Année 45, 1893, pp. 819-820.

(2) Ibid., “ Sur le pancréas du Crénilabre, et particuliérement sur
le pancréas intra-hépatique,” Rev. Biol, du Nord de la France, 1895,
No. 9, pp. 343-360,

(3) Massari, “Sul pancreas di pesci,” Rend. R. Accad. det Lineet,
1898, vol. 7, pp. 134-137.

(4) Diamarg, V., “Studii comparativi sulle isole di fengerhans
del pancreas,” Fate: Monatsschr. I Anat. u. Phys., Bd, 16, 1899,
pp. 155-209.

ON A METHOD OF PREPARING THE MEMBRANOUS
LABYRINTH. By Apert A. Gray, M.D., F.R.S.E.

Our anatomical knowledge of the soft parts of the internal
ear has been obtained not by observations made upon the organ
as a whole, but by piecing together the appearances seen in
fragments. It is nothing short of astonishing how anatomists
have been able to do so with such accuracy. Nevertheless such
a state of matters is in the highest degree unsatisfactory, for it
means that few anatomists will be willing to spend the requisite
time to acquire their knowledge from nature, and no preparations,
so far as I know, exist from which students can learn the
subject in the same way. Furthermore, it is in human nature
to desire the view of any object in its entirety, not as broken
fragments.

Several methods have been described with the object of
obtaining the labyrinth as a whole, but they seem to have
failed, and in my experience of them they failed completely.

At intervals during the past two years I have made many
attempts in various directions, but only recently have I found
out a method which can be depended on to give certain
results.

The general principle of my method is to embed the whole
pyramid of the temporal bone so thoroughly that no acid can
affect the soft parts, then to decalcify and disintegrate the bone
so completely that no force whatever is required to remove the
destroyed tissue surrounding the labyrinth, and finally to remove
the embedding material in such a way that the membranous
labyrinth is left uninjured.

The pyramid of the human temporal bone is removed from
the base of the skull in the post-mortem room. The superfluous
bone is removed with a saw; the stapes is carefully extracted
from the oval window, and a small hole is filed in the superior
semicircular canal. The structure is then immersed in 90 per
cent. alcohol for at least a fortnight, the alcohol being frequently
changed. It is then transferred to absolute alcohol, where it
remains at least a fortnight, this alcohol also being frequently

VOL. XXXVIL. (N.S. VOL. XVII.)—JULY 1903. 26

380 DR ALBERT A. GRAY.

changed. During this period it must be kept in a glass
stoppered jar. The alcohol obtained from the chemist is not
really absolute; it may be made so, however, by putting an
ounce of anhydrous sulphate of copper to every pound of alcohol.
When wanted for use, the clear alcohol at the topis poured off
as desired, care being taken that the sulphate of copper does not
pour out along with it.

From absolute alcohol the bone is removed quickly to xylol,
where it again remains at least a fortnight, the xylol being fre-
quently changed. I find that if a vacuum, more or less complete,
be made now and then in the jar above the level of the xylol,
diffusion occurs much more rapidly and completely. I do this
by fixing an india-rubber cork, with a glass tube through it, into
the mouth of the jar, and extracting the air and gases through a
rubber tube connected with a small air-pump.

From the xylol the bone is removed to melted paraffin of a
melting-point of 52° C. or 54° C. The paraffin must be changed
two or three times during the fortnight which must be allowed
for the embedding. This is important to the success of the
method; the paraffin must permeate the soft parts far more
completely than is necessary in the case of embedding for
microscopic section purposes. I frequently make use of the
air-pump to produce a vacuum above the melted paraffin, but
sometimes the latter solidifies during the process; this, however,
does not appear to affect the ultimate result. Of course the
temperature of the paraffin stove must not be allowed to rise
above 55° or 56° C.

After the bone has been in the paraffin bath for a period
ranging from two to three weeks, the paraffin is cooled as
quickly as possible and the bone cut out from the block. The
superfluous paratiin is then carefully scraped off the bone and
decalcification is proceeded with.

For this purpose neither nitric nor hydrochloric acid by itself
is suitable; they should be mixed. The solution I use consists
of 2 parts pure nitric acid, 2 to 3 parts pure hydrochloric

acid, and 6 to 18 parts water; the nitric acid should be

mixed with the water first, and the hydrochloric acid added.
The bone is put into a large quantity of this mixture and sus-
pended near the top by fine twine. The mixture should be

:
:

METHOD OF PREPARING THE MEMBRANOUS LABYRINTH. 381

frequently changed, and in about three weeks or a month
decalcification and disintegration will be complete. It will be
found that while the cancellous portions of the bone are still
firm, being supported by the paraffin, the dense bone which
surrounds the labyrinth will have become quite pulpy ; indeed
the labyrinth should lie almost loose in the pulp; if this is not
so, the preparation should be put back into the acid and left
longer, and the solution should be made stronger by adding a
little more hydrochloric acid.

After decalcification the mass should be thoroughly washed
for twenty-four hours in gently running water, care being taken
that it does not get roughly handled during the process.

Some of the cancellous portions of the bone may now be
picked very carefully away with the point of a sharp knife, and
then the mass is carefully removed to absolute alcohol, where it
remains for about ten days, the alcohol being changed several
times. From the alcohol it is transferred rapidly to xylol,
which slowly dissolves out the paraffin and leaves the mem-
branous labyrinth transparent. Surrounding portions of
cancellous tissue may be slightly adherent, but they can be
separated by fine sharp scissors as the structure lies in the
xylol. If the dehydration has been thorough, the extremely
delicate structures do not collapse or shrink when the paraftin
is removed. The specimen is preserved in xylol in the glass jar
when the paraffin has been melted out. The courses of the
_ Various portions of the nerves stand out very plainly, and may
be shown still more clearly if the specimen has previously been
stained and fixed with osmic acid.

Very pretty specimens may also be made by injecting the
endolymph spaces (before hardening) with carmine gelatine,
the injection being done through the aqueductus vestibuli,

The blood-vessels may be injected through the internal
auditory artery, also of course before hardening.

TWO HEARTS SHOWING PECULIARITIES OF THE
GREAT VEINS. By Davin Naparro, M.D., M.R.C.P.,
Assistant Professor of Pathology, University College, London ;
Pathologist to the Evelina Hospital for Children, Southwark.

THE two specimens described in this paper were exhibited at
the meeting of the Anatomical Society held on July 3rd, 1902,
and as they show rare abnormalities of the great veins, I have
thought it expedient to record them. Both occurred in patients
at the Evelina Hospital for Children, under the care of Dr F.
Willcocks.

A. The first specimen is’ that of a heart in which all the
pulmonary veins opened into the right auricle through a large
coronary sinus.

The patient, a female child aged 54 months, was admitted
into hospital on April 18th, 1902.

The history is as follows:—The child was born prematurely
(at 8 months). At first nothing special was noticed about her
colour, but when 3 months old she used to wake screaming
and fighting, as though to get her breath, and went ‘black’ in
the face on those occasions. She had three or four of these
attacks in the day. The baby was noticed to be wasting about
one month before admission, and during this time she suffered
also from bronchitis. The lips and extremities were of a
blue colour during the last four weeks of life. Bulging of the
precordium was obvious to inspection three weeks before
admission, and increased up to the time of admission into the
hospital. Apparently the child seemed easier when lying on its
stomach or against the nurse’s chest. After the attacks of
cyanosis the face is said to have been swollen, and on the day
before admission the feet were also swollen. The child was
breast-fed until admitted to hospital.

Condition on admission.—The child was small, but fairly long,
and of very slender build; 203 inches long and 133 inches round
the chest. Cry feeble; breathing very rapid (about 68 per
minute) and apparently ineffectual, though attempts were made

TWO HEARTS SHOWING PECULIARITIES OF THE GREAT VEINS. 383

at deep breathing. The eyebrows were raised with inspiration,
and the child yawned occasionally. The skin was of a dusky
tint, the lips blue (rarely reddish), the veins of the fingers large,
the finger-tips cyanosed and beginning to show clubbing. Slight
cedema of the feet was present.

The chest was barrel-shaped, and moved very little with
respiration. There was obvious fulness in front, especially in
the precordial region. The heart’s impulse could not be felt.
The area of cardiac dulness was increased, extending upwards to
the 2nd intercostal space, outwards 1} fingers-breadth beyond
the nipple line and to the right border of the sternum, probably
not beyond. On auscultation, the heart sounds had a ‘gallop.
ing’ rhythm, and a loud murmur, probably systolic in time, was
heard, best in the-nipple line. Elsewhere the sounds were
‘distant.’ There was some suspicion of a tricuspid regurgitant
murmur. The right lung was apparently normal, except for
crepitations at the base. The left side of the front of the chest
was scarcely resonant at all.

While in hospital the child was constantly blue and cold.
T. rarely above 97° F.; breathing very rapid; pulse weak and
_ running. She remained in much the same condition until the
22nd April, when taken worse, and she died at 4 a.m. on the
23rd.

The autopsy was done about twelve hours after death.

On opening the body in the ordinary way, the pericardium
was seen to be very big, the thymus small, and the left lung was
not visible at all. The heart was ‘globular’ in shape, and the
whole of the anterior surface was constituted by the right
ventricle. The interventricular furrows were present, and the
left ventricle seen to be small. The aorta was considerably
narrower than the trunk of the pulmonary artery. The ductus
arteriosus was easily dissected out, but was very small, and on
subsequent further dissection found to be impervious, only a
depression being present in the interior of the pulmonary artery
where the ductus arteriosus was given off. The large branches
of the aorta were normal. The superior vena cava was consider-
ably smaller than the inferior. Both cave ended normally in
the right auricle, which was very much bigger than the left.

The rightauricle, on beingopened up, was seen to be considerably

384 PROFESSOR DAVID NABARRO.

larger than normal (fig. 1). Its walls were much thickened and
hypertrophied. The auricular appendix was very well developed,
and its walls had prominent musculi pectinati. A well marked
Eustachian valve was present in front of the orifice of the
vena cava inferior, and the inner cornu of the Eustachian
valve was continuous with the anterior limb of the annulus of

Fic, 1 (Case A.).—Semi-diagrammatic view of right auricle and ventricle. R.V.,
right ventricle (cut open) ; C.S.0., opening of enlarged coronary sinus into
right auricle; E.V., Eustachian valve; V.C.I., inferior vena cava (cut
open); F.O., foramen ovale; V.C.S., superior vena cava (opened out) ;
R.Ap., right auricular appendix ; T.V., flaps of tricuspid valve.

Vieussens. The interauricular septum was well formed, only a
small slit-like foramen ovale (3 mm. by 1°5 mm.) being present.
In the situation of the orifice of the coronary sinus was a very
large oval aperture, bounded by the annulus Vieussenii, the
Eustachian valve, and the auriculo-ventricular ring.

TWO HEARTS SHOWING PECULIARITIES OF THE GREAT VEINS. 385

This aperture (fig. 1, C.S.0.) was subsequently seen to lead
from an abnormally large coronary sinus into the right auricle.
On slitting up the openings of the four pulmonary veins, an
irregularly quadrilateral cavity (fig. 2) was discovered, which
was at first thought to be a part of the left auricle, shut off by
a septum from the main body of the auricle and the appendix.

Fic. 2 (Case A.).—View of the heart from the left and behind, showing the enlarged
coronary sinus (receiving four pulmonary veins and the great cardiac vein).
L.V., left ventricle ; L.Ap., left auricular appendix—(to its right in the
figure is the small left auricle unopened) ; P.A., pulmonary artery ; Ao.,
aorta ; P.V., orifices of the pulmonary veins ; C.S., coronary sinus; Br.,
bristle passed through the orifice of the great cardiac vein ; C.S.O., opening
of coronary sinus into right auricle ; I.F., posterior interventricular furrow ;
R.V., right ventricle.

Closer study of the anomaly, however, showed that this cavity
had no connection with the left auricle, but was really a big
coronary sinus, into which the pulmonary veins opened. Two
facts indicate clearly that this cavity is really a dilated coronary
sinus: (1) the opening into the right auricle, although much
larger than normal, is in the situation of the orifice of the
coronary sinus of the heart ; and (2) the great cardiac vein opens
into this sinus (a bristle is passed through this orifice,—see fig. 2).

386 PROFESSOR DAVID NABARRO,

The right ventricle was much larger than normal, and its walls
greatly thickened. There were well marked columne carnes,
the tricuspid valve was normal, as were also the chorde
tendinee. The pulmonary artery was larger than usual, but
was otherwise normal, the three semilunar flaps looking quite
healthy. The trunk of the pulmonary artery soon divided into
the two main branches, and at a distance of about 18 mm. from
the commencement of the arterial trunk was a small depression
in the wall of the vessel, indicating the origin of the ductus
arteriosus, which, however, was completely obliterated.

The left side of the heart was seen to be but poorly developed.
The left auricle, not being fed by the pulmonary veins directly,
was a small cavity (see fig. 2), to which a small appendix was
attached. The only entrance into the left auricle was from the
right auricle, by way of the slit-like foramen ovale. The left
ventricle was small. The smoothness of the walls was a notice-
able feature, hardly any trabecule being present. The mitral
orificeappeared normal in structure, but was on a diminutive scale,
the cusps, chorde tendinez, and the musculi papillares being all
much smaller than on the right side. The left ventricular wall
was thinner than the right. The aorta, which was considerably
smaller than the pulmonary artery, was given off by the left
ventricle, and was furnished with a valve of three semilunar
flaps as usual.

The heart, with a short length of great vessels attached,
weighed 59 grammes, or more than double the weight of a
normal heart of a child of the same age.

Physiologically, this heart is of considerable interest, for it
appears that all the blood for the systemic circulation had to
pass through the small foramen ovale; and further, the left side
of the heart never received pure arterial blood, unless some
disposition of the valves and orifices directed the current of
arterial blood from the dilated opening of the coronary sinus
through the right auricle to the foramen ovale, and so straight
into the left auricle. There is no evidence that such was the
case. The circulation would probably have been as follows:
Venous blood from all parts of the body (except the heart itself)
entered the right auricle through the two cave. Arterial blood
from the lungs entered the dilated coronary sinus through the

oe

TWO HEARTS SHOWING PECULIARITIES OF THE GREAT VEINS. 387

pulmonary veins, and mixed with the venous blood from the
heart brought in by the cardiac veins. This arterialised blood
flowed through the orifice of the coronary sinus into the right
auricle, and presumably became intimately mixed with the
venous caval blood. The mixed blood flowed partly into the
right ventricle, to be sent to the lungs, and partly into the left
auricle through the very small foramen ovale, and so to the
left ventricle. In this way the left side of the heart and the
systemic circulation must have received a smaller quantity of
blood than the right heart and the pulmonary circulation. This
is evidenced by the smaller size of the left auricle, left ventricle,
and aorta, as compared with the right auricle, ventricle, and
pulmonary artery.

Another possible explanation of the great size of the right
ventricle is that this chamber had to do the work of both sides
of the heart. If tricuspid regurgitation were actually present
{as was thought to be possible during life), then the systole
of the right ventricle, besides driving blood to the lungs through
the pulmonary artery, would have forced blood back into the
right auricle, and through the foramen ovale into the left
auricle. |

It is interesting to note that the ductus arteriosus: is not
patent. That the child lived for nearly six months under such
conditions seems remarkable.

The origin of the anomaly is to be explained as follows :
Normally, the pulmonary veins grow into the mesocardium, and
join into a common sinus which opens into the left auricle near
the septum. In this case the aperture of the sinus of the
pulmonary veins, instead of adhering to and opening into the
back of the left auricle, seems to have formed its attachment a
little lower down, and thus to have formed an opening into the
part of the sinus venosus which normally forms the coronary
sinus.

B. The second specimen is that of a heart showing a per-
sistent left superior vena cava, which was joined by a left hepatic
vein.

The patient, a male child aged 3 months, was admitted into
hospital on August 29th, 1901, suffering from pneumonia, to

388 PROFESSOR DAVID NABARRO.

which he succumbed on Sept. 9th. During life no abnormality
of the vascular system was suspected.

The post-mortem examination was made fifteen hours after
death. The right lung was pneumonic, the left emphysematous.

Just before removing the heart from the body it was seen
that the left innominate vein, instead of crossing over as usual
to join the right innominate, was continued down as a left
superior vena cava, rather smaller in calibre than the corre-
sponding vessel on the right side. It passed down in front of
the root of the left lung, crossing the aortic arch just beyond
its junction with the ductus arteriosus, and then disappeared
behind the left auricle, lying in a groove between the left auricle
proper and its appendix (see fig. 3) A transverse jugular vein
(in the situation of the normal left innominate vein) was not
seen, but was not specially looked for.

The azygos veins and their tributaries were carefully dissected
out, with the following result (see fig. 4), On the right side
the vessels were normal, and the great azygos formed the
usual arch before its junction with the superior vena cava.
On the left side, the highest intercostal vein could not be
traced. The 2nd, 3rd, 4th, 5th and 6th united to form one
trunk (representing the left upper azygos and the superior
intercostal veins), which arched over the root of the left lung
and joined the left superior vena cava. The 7th, 8th and 9th
intercostal veins formed another trunk, which crossed the spine
and entered the right azygos. The other intercostals could not
be traced with any certainty. It was at the lower end that
this persistent left cava was most interesting. A probe passed
down the vessel was found to go directly into a left hepatic
vein, a vessel of considerable size, coming from the left lobe of
the liver, and not communicating with the other hepatic veins.
This left hepatic vein was joined by a vein from the left side
of the diaphragm (see figs. 3 and 4).

As far as they were examined, the other veins in the body
were normal. I regret, however, that I omitted to search for a
ductus venosus, or any remnant of it.

The heart was then removed from the body and opened in
the usual way. The right auricle showed, in the position of
the normal aperture of the coronary sinus, a large oval opening,

TWO HEARTS SHOWING PECULIARITIES OF THE GREAT VEINS. 389

by which blood entered from the left superior cava. There
was a small foramen ovale in the auricular septum. Entering
the inferior vena cava are seen three hepatic veins—two very
large and one small (see figs. 3, 4).

The left superior vena cava was next slit down, also the left
hepatic vein and the intervening cardiac chamber (see fig. 3).

LSVC. R.SMC.

GCV

LiAe< cures

HN/
PCV. —~
Lu—
wy vei

MCY.

Fic. 3 (Case B.).—View of the heart from the left side and behind, showing the
enlarged coronary sinus receiving the left superior cava, a left hepatic vein,
as well as the great and middle cardiac veins. L.S.V.C., left superior cava ;
L.A., left auricle; R.S.V.C., right superior cava; R.A., right auricle ;
H.V., hepatic veins ; V.C.1., inferior vena cava ; L.H., a left hepatic vein ;
P.C.V., large posterior cardiac vein ; M.C.V., middle cardiac vein ; G.C.V.,
great cardiac vein; L.Ap., left auricular appendix ; C.S., coronary sinus ;
L.V., left ventricle.

This, which is a true sinus venosus, is a small chamber with
smooth walls, opening into the right auricle by the large oval
aperture mentioned above. Near this opening and just above
the auriculo-ventricular groove is a small hole through which
the blood from the great cardiac vein flowed. In the wall of
the cut left hepatic vein is seen the orifice of the left phrenic
vein (see fig. 3).

390 PROFESSOR DAVID NABARRO.

The left auricle, the ventricles, aorta, and pulmonary artery
were all normal.
The abnormal condition of the veins found in this case is

Tv. | | RSVG Lx

RAV.

VJ.

Fic. 4 (Case B.).—Sketch of the principal veins, showing the left’ superior cava
and the disposition of the intercostal and azygos veins. R.S.V.C., right
superior cava ; J.V., jugular veins; S.V., subclavian veins ; R.Az.V., right
azygos vein ; H.V., hepatic veins; V.C.1., inferior vena cava ; L.H., a left
hepatic vein ; P.V., a left phrenic vein ; C.S., coronary sinus; L.Az.V., left
upper azygos vein ; L.S.V.C., left superior cava.

readily explained by reference to what is known of the develop-
ment of these vessels. Examples of a persistent left 8.V.C. or
duct of Cuvier are recorded from time to time, but it is

TWO HEARTS SHOWING PECULIARITIES OF THE GREAT VEINS. 391

apparently very rare to find the left hepatic vein piercing the
diaphragm and entering the left horn of the sinus venosus with
the left duct of Cuvier, as is the case in this specimen.

In an early stage of development (about 4th week in the
human embryo) two superior vene cave (right and left) and
an inferior cava open separately into the sinus venosus.
Normally, the left duct of Cuvier with the left horn of the
sinus venosus becomes obliterated, with the exception of a small
part forming the definitive coronary sinus of the heart, while
the right duct of Cuvier persists as the superior vena cava, and
the right horn of the sinus venosus becomes incorporated with
the cavity of the right auricle. Ata rather earlier stage (about
34 weeks in the human embryo) the sinus venosus received a
superior vena cava at each extremity, also two omphalo-
mesenteric veins. The superior V.C. on each side receives
the primitive jugular and the cardinal veins. In this case the
arch of the left cardinal vein, instead of being obliterated as
usual, persists as the arch of the left azygos vein.

The omphalo-mesenteric veins, opening directly into the sinus
venosus, become the hepatic veins, and normally these all join
up on the right side and enter the inferior V.C. The direct
communication of the left hepatic vein with the sinus usually
becomes obliterated early, but in this case it has persisted, and
entering with the left duct of Cuvier, forms a persistent left
horn of the primitive sinus venosus.

I desire to express my great indebtedness to Professor Thane
for his valuable assistance in the elucidation of these rare and
interesting abnormalities and of their probable mode of causa-
tion. I am likewise indebted to Dr F. Willcocks, Physician to
the Evelina Hospital, for permission to use the notes of these
cases.

THE GENERAL CHARACTERS OF THE CRANIA OF THE
PEOPLE OF SCOTLAND. By Sir Wm. Turner, K.C.B.,
F.R.S.

In November 1902 I communicated to the Royal Society of ree 3
a Memoir on the Craniology of the People of Scotland, in which I de-
scribed the anatomical characters of 176 skulls.’ The skulls were
collected in known localities, from Shetland in the north to Wigtown-
shire in the south, and from Iona and Stornoway in the west to
Dunbar in the east ; but as the majority were gathered in the counties
south of the Clyde and the Tay, the memoir is more especially
descriptive of the people of Lowland Scotland. In one of the chapters
of the memoir I gave a general summary of the characters of the
series of skulls; and in order to bring the conclusions arrived at in
their study before a wider circle of readers, I have reprinted it in this
number of the Journal,

GENERAL SURVEY OF THE CHARACTERS OF SCOTTISH SKULLS,

In the preceding sections of the Memoir the characters of the skulls
obtained in the several Scottish counties have been described in some
detail. In this chapter it is intended to look at them as a whole, with
the view of elucidating the form, dimensions and proportions which
prevailed in the crania generally. I have endeavoured to group them
according to sex ; and though in the great majority I have succeeded
in distinguishing the skulls of the men from those of the women, it is
not unlikely that, like other craniologists, I have had to deal with a
few specimens in which the sex characters were wanting in precision,
and consequently a skull may possibly have been ascribed to the wrong
sex. If we grant that this has occurred in a small minority, yet from
the numerous specimens at my disposal, in which the sex could con-
fidently be stated, the general conclusions cannot have been materi-
ally affected.

I propose, in the first instance, to analyse the dimensions, propor-
tions, and form of the cranial box, and afterwards to consider those of
the face.

The Cranial Box.

The shape of the cranium, from its influence on the form of the
head and from its association with the brain contained in its cavity,
has attracted attention from the earliest periods of craniological
research. Since the time of Anprrs Rerzivus the relations of the
length to the breadth and the grouping of skulls into those in which
the cranium is relatively narrow and elongated, and those in which it
is more rounded in form, have been regarded as of great importance
in the recognition of racial distinctions. According to modern

' Trans. Roy. Soc, Edin., vol. xl. part iii., 1903.

GENERAL CHARACTERS OF CRANIA OF PEOPLE OF SCOTLAND. 393

methods the character of the cranium can be determined by combining
observations on its shape with exact measurements. The measure-
ments are taken with caillipers in straight lines between certain
definite points, in order to determine the length, breadth, and height
of the exterior of the box; with a graduated tape over the curved
walls of the outer table so as to determine its arcs and circumferences,
and with shot to estimate its internal capacity. The points of
measurement in the straight lines are indicated by the terms employed
in the Tables.' The measurements of the curved surfaces, whilst
agreeing with the methods pursued in my memoirs in the Challenger
Reports? and in my two memoirs on Indian crania* in regard to the
horizontal circumference, the vertical transverse arc, and the frontal,
parietal, occipital and total longitudinal arcs, have in this memoir
been somewhat amplified so as to yield a vertical transverse circum-
ference and a total longitudinal circumference, dimensions which for
the first time are definitely stated in my Tables. The vertical trans-
verse circumference is obtained by measuring with callipers a basal
transverse diameter between opposite supra-auricular points, and
adding this to the vertical transverse arc. The data for obtaining a

total longitudinal circumference existed in the Tables in my previous
_ memoirs, and consisted of the total longitudinal arc, the antero-

posterior diameter of the foramen magnum, and the basi-nasal
diameter; in this memoir the respective measurements have been
added together and stated collectively in the Tables. The capacity of
the cranial cavity has been taken by the method described in my
Challenger Report, 1884, and the additional experience of its accuracy
which I have had since that date has added to my confidence in the
method as giving a close approximation to the real capacity, and not
an exaggerated statement of the cubage, such as is obtained by the
well-known method of Pau Broca.

Speaking generally, and subject of course to occasional exceptions,
we may say that the Scottish cranium is large and capacious; the
vertex is seldom keeled or roof-like, but has a low rounded arch in the
vertical transverse plane at and behind the bregma, and with a gentle
slope from the sagittal suture to the parietal eminences. The side
walls are not vertical, and bulge slightly outwards in the parieto-
squamous region, so that the greatest breadth is usually at or near the
squamous suture. The occipital squama bulges behind the inion, and
the slope from the obelion is downwards and backwards, so as to give
in the norma verticalis an obliquely flattened character to the post-
parietal region, but without occasioning a vertical parieto-occipital
flattening such as is found in many normal brachycephalic crania, or
in those in which artificial compression is employed in infancy.
Owing to the width in the parieto-squamous region and the projecting
occipital squama (probole) in many crania, their outline is more or less
pentagonal, the frontal region forming one boundary, the sides of the
cranium as far back as the parietal eminences forming two others, and

1 The Memoir contains seventeen Tables of measurements.

2 Zoology, part xxix., 1884, and part xlvii., 1886,
3 Trans, Roy. Soc. Edin., part i., 1899 ; part ii., 1901,

394 SIR WILLIAM TURNER.

the remaining two sides are the walls from the parietal eminences to
the most projecting part of the occiput. Im men the glabella and
supraorbital ridges are fairly but not strongly pronounced, the fore-
head only slightly recedes from the vertical plane, and the nasion is
scarcely depressed.

Length.—The glabello-occipital or maximum length was measured
in one hundred and seventy-six crania, viz., one hundred and seven-
teen men and fifty-nine women. In the men the longest skull was
204 mm., and eight were 200 mm. and upwards; thirty-three were
from 190 to 199 mm., so that nearly one-fourth of these crania were
above 190 mm. in greatest length. The shortest skuil in the men was
167 mm., and only sixteen crania were below 180 mm. in their
greatest length. The longest skull in the women was 193 mm., and
only three crania were 190 mm. and upwards; the shortest woman’s
skull was 161 mm.; and eight crania were below 170 mm. The
mean length of the male crania was 186°6 mm., that of the female
crania was 178°7 mm.

The projection of the glabella was not, even when most prominent,
equal to what one sees in the long skulls of so many Australian and
other black people, and consequently the length of the Scottish skull
indicated a cranial cavity and a brain longer than existed in the
dolichocephalic black races. Owing, however, to the depth of the
frontal sinuses and the thickness of the frontal and occipital bones
the cranial length from the glabella to the occipital point is appreci-
ably greater, especially in the male sex, than the long diameter of the
cerebrum. In order to eliminate the frontal sinus with the consequent
projection of the glabella from the comparison, and to associate the
length of the skull more closely with the length of the cranial cavity
and the cerebrum, it was suggested by Dr RoLiesron’* that the point
to be selected in front for taking the cranial length should be the
ophryon, a point immediately above the glabella. The observations of
A. Logan TuRNER? have shown that the frontal sinus is not limited
to the region of the glabella and supraorbital ridges, but extends in a
large proportion of skulls above the ophryon, so that the influence of
the sinus in adding to the cranial length is by no means eliminated by
selecting the ophryo-occipital in preference to the glabello-occipital
diameter. (Vigs. 25, 26, pl. v. of the original Memoir.)

Breadth.—The greatest parieto-squamous breadth was obtained in
one hundred and seventy-four crania, viz., one hundred and fourteen
men and sixty women. In the men the broadest skull was 159
mm., and twenty-four crania were between 150 and 159 mm. The
narrowest male skull was 130 mm., and twenty-six skulls ranged from
130 to 139 mm. In the women the broadest skull was 153 mm.,
two specimens being of that diameter. The narrowest skull was
128 mm., and thirty-six specimens ranged from 130 to 139 mm.,
whilst nineteen were between 140 and 150 mm. The mean breadth
of the male crania was 149°3 mm., that of the female was 138 mm.

? In Greenwell’s British Barrows, p. 506, 1877, and in vol. i. Scientific Papers
and Addresses, edited by W. Turner.
2 Accessory Sinuses of the Nose, p. 105. Edin., 1901.

1 i a oe

GENERAL CHARACTERS OF CRANIA OF PEOPLE OF SCOTLAND. 395

This diameter approximates to the greatest breadth of the cerebrum
in each individual.

In addition to the parieto-squamous breadth the Tables contain the
minimum and stephanic breadth measurements of the frontal region,
as well as the asterionic diameter which gives the breadth of the
occipital bone between its lateral angles. As a general rule the
frontal stephanic diameter materially exceeded the minimum frontal,
though in a few instances it was not more than from 2 to 8 mm.
greater. These dimensions give an approximation to the width of the
frontal lobes of the cerebrum. Twenty-three crania had a persistent
frontal suture, viz., sixteen males and seven females. The metopic
erania as a rule exceeded in their frontal diameter the skulls of the
corresponding sex from the same locality in which the frontal suture
was ossified, and confirmed the view entertained by many craniologists
that persistence of the frontal suture contributes to an increase in
the transverse diameter of the skull and brain in that region.

The asterionic diameter, except in one skull, was greater than the
minimum frontal, but as a rule it was less than the stephanic, though
there were several exceptions. This diameter may be regarded as
giving an indication of the breadth of the.cerebellum.

Cephalic Index.—As is well known, this index expresses the re-
lation which the greatest parieto-squamous breadth of a skull bears to
its maximum length, the length being regarded as =100, and the
formula is as follows :

greatest breadth x 100
maximum length

_ The index was obtained in one hundred and seventy-four skulls,
one hundred and fourteen of which were males and sixty were females.
The index showed a great range of variation from 87°2 to 68°2._ The
mean length-breadth index in the men was 77°4, in the women 77:2.
Both sexes, taken collectively, had essentially the same mean index,
and were in the middle of the mesaticephalic group. If we follow
the customary arbitrary grouping of crania according to the length-
breadth or cephalic index, we find that forty-nine skulls were below
75, t.e. dolichocephalic ; ninety skulls were between 75 and 79°9, 7.e.
mesaticephalic (mesocephalic) ; thirty-five skulls were 80 or upwards,
i.e, brachycephalic.

Although it is a matter of convenience to accept a mesaticephalic
group, interposed between the more extreme dolichocephalic and
brachycephalic forms, it should be kept in mind, as I have stated in
my memoir on Indian craniology,' that if we take 77-5 as marking a
division of this group into two sections, the skulls which have an
index between 77°5 and 80 approach in their characters more closely
to the brachycephalic, whilst those that range from.77°5 to 75, on
the other hand, are more allied to the dolichocephalic type. In these
erania forty-five mesaticephali had their indices from 77°5 to 79°9, in
no fewer than eighteen of which the index was between 79 and 80,

1 Trans. Roy. Soc. Edin,, vol. xxxix, p. 744, 1899.
VOL. XXXVII (N.S. VOL, XVIL)—JULY 1903, 27

396 SIR WILLIAM TURNER.

brachycephalic therefore in form, though they were fractionally below
its lowest numerical limit.

It is obvious, therefore, that a strong brachycephalic strain per-
vades the population of Scotland at the present time, as in no fewer
than fifty-three crania of this series the index was 79 or upwards,
either numerically brachycephalic or closely approximating thereto.
If expressed in percentages we may say that 207 were numerically
brachycephalic and an additional 10% had a cephalic index from 79
to 79°9; on the other hand, 28% were dolichocephalic, and in 427,
the index ranged from 75 to 7 9.

The relative proportion of the more rounded to the more alongsted
heads varied, however, materially in the different counties. Of the
sixteen skulls from Fife six had the index above 80, one of which was
hyperbrachycephalic, two were 79°7, three were between 77°5 and 79.
In the Lothians, including Edinburgh and Leith, of seventy-nine
skulls twenty had the length-breadth index 80 and upwards, and of
these four were hyperbrachycephalic; eight crania also ranged from
79 to 79°9 and were thus essentially brachycephalic, whilst fourteen.
ranged from 77°5 to 78°9. In the group of nine skulls from Stirling-.
shire, Lanarkshire, Peebles, and Roxburghshire, two had a length-
breadth index above 80, and one of these was hyperbrachycephalic,
and three others were 78 or 781. The Renfrewshire group of twenty-
one crania, on the other hand, had no specimen with an index as high
as 80, though three were between 79 and 80, and three were from
77°5 to 79. The three skulls from Ayrshire had one brachycephalic
example. Of the six skulls from the north-eastern counties of Forfar,
Kincardine, and Banff, four had the length-breadth index 80 or up-
wards, and one of these was hyperbrachycephalic; the remaining two
were 79'7 and 79°9 respectively, and were essentially brachycephalic..
In the five crania from Shetland, one was hyperbrachycephalic, and
another had the index 79°4. Of the five crania from Iona the two
highest were 79 and 79°3 respectively. In the miscellaneous series of
sixteen crania from the dissecting-room, only one had an index 80, no
specimen was between 79 and 80, and four were from 77°5 to 79.

Our attention should now be directed to the distribution of dolicho-
cephalic crania in the different counties; and along with those whose
index is below 75, we shall consider the crania in the mesaticephalic
group with an index between 75 and 77:4. In the Fifeshire group
only three had the length-breadth index below 75, and two were
75°5 and 76 respectively. Of seventy-nine skulls from the Lothians
twenty were below 75, and two of these were hyperdolichocephalie,
while sixteen ranged from 75 to 77°4. Two crania from Lanark
were below 75, and one of these was hyperdolichocephalic ; two from,
Roxburgh were 76°2 and 76°3 respectively. In the Renfrewshire group
eight skulls were dolichocephalic, and seven were between 75 and
76°7. Two of the three Ayrshire skulls were 75 and 75:9 respectively.
Two of the four Wigtownshire were dolichocephalic, the other two
were 75°8 and 76°5 respectively. No skull from Shetland was below
75, but three were from 75°1 to 77:4. In three crania from Caithness
and six from the Highland counties of Argyll, Perth, Ross and

-—

T= -o~. --
7 Evy

GENERAL CHARACTERS. OF CRANIA OF PEOPLE OF SCOTLAND. 397

Sutherland, the length-breadth index was in no instance above 75,
and two of these were hyperdolichocephalic. Five of the’ seven
crania from the Hebrides ranged from 74°2 to 77. Seven of the
oo series were below 75, and four ranged from 75°7 to
7771.

From this analysis of the cephalic indices in the crania under
observation it would appear that a brachycephalic type of skull
prevailed in Fife, in the Lothians, in the north-east counties of Forfar,
Kincardine, and Banff; and it occurred to some extent in Shetland, in
Ayr, in the border county of Peebles, and in Stirlingshire.

The dolichocephalic type of skull was feebly represented in Fife ;
it was proportionately more numerous in the Lothians, in which
district are included the skulls from Edinburgh and Leith; it was
represented in Lanark, Ayr, Shetland, and the Hebrides. It formed
the prevailing type in Wigtownshire, in Caithness, in the skulls from
the Highland counties, and in the important series of skulls from
Renfrewshire. Whilst examples of this type occurred generally
throughout the series, it may be noted that only five hyper-
dolichocephali, z.c. skulls with the index below 70, were measured,
but that eight hyper-brachycephalic crania, 7.e. with the index 85 and
upwards, occurred in the series.

In the study of the Scottish brachycephalic crania I have been led
to compare them with crania of some other races measured by me
some years ago, which had numerically this type of head. The
comparison has been made with twenty-four male Burmese skulls !
and with eight skulls of male Sandwich Islanders? described in
previous memoirs, in each of which the cephalic index was 80 or
upwards. The mean length-breadth index in the Burmese brachy-
cephali was 84°2._ The shortest skull in this group was 158 mm., the
longest was 184, and the mean length was 171°8 mm. The parieto-
squamous breadth ranged from 139 to 153 mm., and the mean
breadth was 144-7 mm. In the Sandwich Islands brachycephali the
mean length-breadth index was 83°8 ; the length ranged from 169 to
184 mm., and the mean was 176°5 mm.; the breadth ranged from
142 to 155 mm., and the mean was 148 mm. In twenty seven male
brachycephalic Scottish skulls the mean length-breadth index was
83-2, almost the same as that of the Burmese. The length ranged
from 167 to 193 mm., and the mean was 180°3 mm.; the breadth
ranged from 140 to 159 mm., and the mean was 150 mm. The
mean length of the Scottish brachycephalic crania exceeded, therefore,
by several millimetres the length of the brachycephalic Burmese and
Sandwich Islanders, The greater lengthin the Scottish brachycephali
was associated with a backward projection of the occipital squama,
which contrasted with the almost vertical post-parieto-occipital
region in the Burmese, Siamese, and brachycephalic Sandwich Islanders,
For the production of a high index in skulls of this type, the breadth

1See my Memoir on Indian Crania, part i., 7rans. Roy. Soc. Edin., vol. xxxix.,
1899.

*See Challenger Report, ‘‘ Zoology,” part xxix., 1884, pp. 64 and 66, and part
x]vii., 1886, p. 125.

398 SIR WILLIAM TURNER.

required to be proportionately increased, and the Scottish brachy-
cephalic crania both in length and breadth were larger and more
capacious than the brachycephalic Burmese and Sandwich Islanders.

Height.—The distance from the basion to the bregma was taken as
expressing the height of the cranium, and it was measured in one
hundred and fifty specimens, ninety-eight of which were males and
fifty-two females. In the men the highest skull was 145 mm. ;
fifteen skulls were between 140 and 145, tifty between 130 and 140,
and thirty-four below 130, the lowest being only 117 mm. in height.
The mean height of the male skulls was 132°4 mm. Inthe women the
highest skull was 140 mm., the lowest was 118 mm., and the mean
was 126. If wecompare the height of the male Scottish crania with
that of the male Burmese already referred to, we find that the mean
height in the latter people was 135 mm., a somewhat greater figure
than in the Scottish specimens.

Vertical Index.—This index expresses the relation which the basi-
bregmatic height bears to the maximum length, which is regarded as
=100, and is computed by the formula

basi-bregmatic height x 100
maximum length ~~

The index was obtained in one hundred and fifty crania,
ninety-eight of which were men and fifty-two women. It was
subject to a great range of variation, from 63°7 to 79°4. The
mean vertical index in the men was 70°9, in the women
70°5; both were metriocephalic,’ and the sexual difference was
very slight, though slightly in favour of the men. The number of
skulls with vertical index 75 and upwards was seventeen; thus a
small proportion only were hypsicephalic or high skulls; sixty-five
crania on the other hand had the vertical index below 70, 7.e. were
low skulls, chamecephalic or tapeinocephalic; the remainder had the
index between 70 and 75 and were metriocephalic, which, as above
stated, was the mean of the entire series.

Breadth- Height Index.—The relations of the length to the breadth
and to the height of the cranium have long been recognised as
important subjects of investigation in the study of the racial characters
of skulls, but the relations of the breadth and height to each other
have not had an equal attention given to them.

In my Challenger Report (1844) I pointed out that in the
brachycephalic crania from New Guinea and other Pacific Islands,
the breadth was as a rule greater than the height, whilst in the
dolichocophalic Papuans the opposite condition prevailed. In
subsequent memoirs, more especially those on Indian craniology, I
called attention to the relations of these diameters in several Asiatic

1] prefer, for the reasons stated in my Challenger Report, 1884, to employ the
descriptive term metriocephalic rather than orthocephalic, as recommended by
the German craniologists in the Frankfurt agreement (Archiv fiir Anthropologie,
Bd. xv. p. 1, 1884). In this memoir I have, however, adopted the numerical
subdivision of the group which they have suggested, viz., chamesbepalal up to
70; metriocephalie (orthocephalic), 70°1-75 ; hypsicephalic, 75°1 and upwards.

—-

ary |

GENERAL CHARACTERS OF CRANIA OF PEOPLE OF SCOTLAND. 399

races. In his work on the accessory sinuses of the nose already
quoted, A. Logan Turner has recorded the proportion of breadth to
height in a large number of crania, European and exotic.

In order to express numerically the relations of the breadth and
height of the cranium to each other, an index may be computed by
the following formula:

dasi-bregmatic height x 100
parieto-squamous breadth ’

the breadth being regarded as 100. The data for obtaining the
index exists in the Tables.

When the index exceeds 100, the height is greater than the
breadth, and the skull is hypsistenocephalic,’ i.e. a high narrow
skull: when the index is less than 100, the breadth is greater than
the height and the skull is platychamecephalic, i.e. a wide low
skull.

From the measurements which I have made of the breadth and
height of the cranium in many races of men, I have ascertained that
in some the height usually exceeded the breadth, whilst in others the
breadth exceeded the height.2, In well-pronounced dolichocephalic
races like the Esquimaux, the Melanesians, the Dravidians, Veddahs,
and the Australians generally, as a rule the height was greater than
the breadth, and the crania were hypsistenocephalic. In the brachy-
cephalic crania of the Burmese, Siamese, Chinese, Andaman
Islanders, and brown Polynesians, on the other hand, the breadth as
a tule was greater than the height and the crania were platy-
chamecephalic. )

In the series of one hundred and fifty Scottish crania in which
both the breadth and height were measured, in only two skulls was
the height greater than the breadth, and in four others they were
equal. In all the rest, whether the cephalic index was high or low,
the vertical diameter was less than the breadth. A striking feature
of the Scottish crania, therefore, was the preponderance of the
cephalic index over the vertical index, notwithstanding the consider-
able number of dolichocephalic skulls in the series, and in this
respect the crania favoured the brachycephalic rather than the
dolichocephalic type. The Scottish skulls are platychamecephalic.

Horizontal Circumference-—This measurement was taken in one
hundred and sixty-three skulls, one hundred and eight of which were
males and fifty-five females. The maximum male skull was 572 mm.,
the minimum was 490 mm., and the mean was 531 mm, The
maximum female skull was 550 mm., the minimum was 470 mm., and
the mean was 506 mm.

1 Dr BARNARD Davis introduced the term hypsistenocephalic to designate the
high, narrow dolichocephalic crania of natives of islands in the Western Pacific
tlre Verhandelingen, Dee|. xxiv., Haarlem, 1886), and I propose that
t should have a more general application, as in the text. The term platy-
chamecephalic is now suggested to designate wide and low crania.

*See my Memoir in Challenger Report, 1884 ; also on New Guinea Skulls in
Proce. Roy. Soc. Edin., July 1899, and on Indian Crania in Trans. Roy. Soc.
Edin., 1899 and.1901.

400 SIR WILLIAM TURNER.

Vertical Transverse Cireumference.—This measurement was made
in one hundred and fifty-three skulls, of which one hundred and
three were males and fifty were females. The maximum male skull
was 464 mm., the minimum was 398 mm., and the mean was 434
mm. The maximum female skull was 459 mm., the minimum was
381 mm., and the mean was 409°6 mm.

Total ‘Longitudinal Circumference.—This dimension was taken in
one hundred and thirty-nine crania, of which ninety-six were males
and forty-three were females. The maximum male skull was 559

mm., the minimum was 468 mm., and the mean was 515-2 mm.

The maximum female skull was 533 mm., the minimum was 441 mm.,
and the mean was 488°8 mm. The high longitudinal cireumference
was found in those skulls in which the glabello-occipital length was
200 mm. or approaching thereto, whilst in the skulls in which this
diameter was smal] the longitudinal circumference was relatively
low.

The total longitudinal are was much the most important factor in
this measurement, and the skulls were sufficiently numerous to
enable me to ascertain the relative lengths of the frontal, parietal and
occipital ares which collectively form the total longitudinal are in
the series of skulls in which the arcs were measured; it was
found that the occipital are in thirteen specimens was greater than
the frontal and ia one hundred and thirty-one it was less; in twenty-
six it was greater than the parietal and in one hundred and twelve
it was less. It is the rule, therefore, for the frontal and parietal
longitudinal arcs to exceed the occipital, though exceptions to the
rule occur in recognisable numbers. The relative ares of the
frontal and parietal bones were measured in one hundred and fifty-
eight crania; in ninety-six the frontal are was longer than the
parietal, in fifty-five the parietal was longer than the frontal,
and in seven they were equal. It is obvious, therefore, that as
so much variation occurs in the relative length of the longitudinal
arcs in the three bones, they have no appreciable value as race
characters in the Scottish skulls, and the variation occurred in both
the brachycephalic and dolichocephalic ype The longest occipital
are was 139 mm., the shortest * mm.; the longest frontal are was

148 mm., the shortest 111 mm. ; the longest parietal are was 148

mm., the shortest 102 mm.

From a comparison of the three circumferential measurements it
will be seen that the horizontal circumference is the greatest, for it
includes both the glabello-occipital and parieto-squamous diameters,
which are the longest diameters in the Scottish crania. The vertical
transverse circumference, again, is the shortest, as the basi-bregmatic
diameter is the shortest of the three dimensions in the Scottish crania.
The total longitudinal circumference ranks intermediate, for it
includes only one of the two longer diameters.

Cubic Capacity.—The internal capacity of the cranium was taken

with shot in accordance with the method which I described in 1884,"

One hundred and fifteen crania were cubed; seventy-three were
1 Challenger Reports, ‘* Zoology,” part xxix., 1884,

GENERAL CHARACTERS OF CRANIA OF PEOPLE OF SCOTLAND. 401

males and forty-two were females. The maximum capacity in the
male skulls was 1855 c.c., the minimum was 1230 c.c., and the mean
was 1478 c¢.c. Thirty-three skulls were more than 1500 c.c., and of
these seven were 1700 and upwards, nine were between 1600 and
1700, seventeen were between 1500 and 1600; further, twenty-two
were between 1400 and 1500, sixteen were between 1300 and 1400,
and four were below 1300 c¢.c. The maximum capacity in the
female was 1625 c.c., the minimum was 1100, and the mean was
1322 ¢.c. Only three female skulls were above 1500 c.c., eight were
between 1400 and 1500, sixteen were between 1300 and 1400,
eighteen were below 1300, and of these six were below 1200 c.c.
The general result approximates to what has been observed in the
erania of other races and peoples, that the female skull is about
10 per cent. less capacious than the male. If I had employed
Broca’s method, by which the cubic contents of so many races have
been taken by anthropologists in France and elsewhere, the average
for both sexes would have heen considerably higher. It is possible,
however, from the Tables compiled by E. Scumunr,! to state the
cubic contents of the Scottish crania approximately in the terms of
Broca’s method, according to which the mean capacity of the males
would have been about 1570 c.c. and that of the females about
1400 e.c. The Scottish male skull therefore is, according to
PBroca’s method of cubage, somewhat in excess of the mean 1500 c.c.
ascribed to the crania of European men.

In twenty-five dolichocephalic crania the mean capacity was 1516
€.c., and in twenty-one crania approximating to the dolichocephali in
which the cephalic index was from 75 to 77°4 the mean capacity was
1519 ¢.c. In thirteen brachycephalic skulls the mean capacity was
1469 c.c., and in fifteen, in which the cephalic index ranged from
77°5 to 79°9, the mean capacity was 1452 ¢.c. A claim has been
made by people whose crania have brachycephalic proportions that a
brachycephalic head is higher in its type than a dolichocephalic. So
far as the quality of type is expressed by the amount of cranial
capacity, the skulls of the people of Scotland do not sustain this claim,
as those with dolichocephalic proportions had a distinctly greater
mean capacity than the brachycephali.

In addition to these more general statements, the Tables enable us
to form some estimate of the existence of differences in the capacity
of skulls from various districts of Scotland, though in many localities
the number measured was too small on which to generalise. In the
male skulls from Fife, Mid-Lothian, Shetland and Renfrewshire, the
average in each group was, according to my measurements, somewhat
more than 1500 c.c.; in East Lothian and Wigtownshire it was slightly
lower than 1500; in the skulls from Edinburgh and Leith, West
Lothian, the North-Eastern Counties, the Highland Counties and the
Dissecting-room, the mean again was still lower. In making this
statement I do not draw any inference that the difference in cranial
capacity had a definite relation to the intellectual endowment of the
people in these localities. Many other factors than the volume of the

1 Archiv fiir Anthropologie, supplement, vol. xiii, p. 58, 1882.

402 SIR WILLIAM TURNER.

cranial cavity have to be taken into consideration in the estimation
of the intellectual power either of individuals, or of a collection of
individuals belonging to the same people or race,

In the comparison of different races with each other there is, how-
ever, evidence that those in which the mean cranial capacity is low
are intellectually inferior to the races whose mean capacity is on a
distinetly higher scale. .

If we take as an example the aboriginal Australians who are
recognised as a race incapable, apparently, of intellectual improvement.
beyond their present condition, my measurements have shown that in
thirty-nine men the mean cranial capacity was 1280 c.c., whilst.
twenty-four women were only 1156 ¢.c, Of the men, eight had a
smaller capacity than 1200 c.c., and four only were above 1400 c.c. ;
whilst in the women ten were below 1100, and only three were 1200:
c.c, and upwards.

The differences between the capacities of the native Australians.
and the Scottish skulls are much more than can be accounted for by
variations in the stature and muscularity of the two peoples, and
undoubtedly express a size and quality of brain associated with
differences in the intelligence and the mental capabilities of the two
races.

The Face.

All craniologists from the time of Pricoarp and Rerzius have —
agreed in stating that in the study of the face it is important to
determine the degree of forward projection of the upper jaw and to
decide if the face is orthognathic or prognathic.

Gnathic Index.—In this memoir I have adopted the method
followed by Sir Wu. H. Firower and compared the length from basion
to nasion with that from basion to the alveolar point. The basi-nasal
length was taken in one hundred and forty-nine skulls, and ranged
in the males from 91 mm, to 110 mm., and the mean was 101°4 mm. ;
whilst in the females it ranged from 86 to 105, with a mean of 95°3:
mm, The basi-alveolar length ranged in sixty-seven males from 81
mm, to 108 mm., and the mean was 96 mm.; whilst in thirty-one
females it ranged from 79 to 102, with a mean of 91 mm,

The gnathic index was computed as follows:

basi-alveolar length x 100
basi-nasal length

Whilst the index gives the numerical relation between the two
(liameters, it does not necessarily express the relative projection of
the upper jaw beyond the profile outline of the face, for in many
skulls the nasion is depressed below the plane of the glabella and of
the forehead generally.

The gnathic index was computed in ninety-seven skulls, sixty-six of
which were men and thirty-one women. It ranged from 85:1 to
103-2, and the mean in the men was 94°5, in the women 94'8. If we
take FLower’s subdivision of the group, and regard an index 103 as
marking the lowest limit of prognathism, only one specimen came

GENERAL CHARACTERS OF CRANIA OF PEOPLE OF SCOTLAND. 403

into that category. Ifan index 98 be taken as marking the upper
limit of orthognathism, seventy-two skulls belonged to this group,
whilst twenty-four had indices from 98 to 103 and were mesognathous.
The Scottish skulls are therefore characterised by an almost complete
absence of prognathism.

It is sometimes stated that in the same race or people the women
show a relatively greater prognathic character than the men. This
can scarcely be said of the Scottish skulls, for the difference between
the two sexes was only fractional, so that for all practical purposes
they may be regarded as identical.

Orbital Index.—Broca paid much attention to the determination
of the height and width of the orbit and to the computation of an
index of their relative proportions. The width was measured from
the dacryon, or point of junction of the frontal, lachrymal and
ascending process of the maxilla, to the most distant point on the
edge of the outer border of the orbit. These measurements were
taken in one hundred and twenty-four skulls. The greatest width
in eighty-four males was 46 mm., the least was 35 mm., and the
mean was 39 mm. ; in forty females the greatest width was 41 mm.,
the least was 35, and the mean was 37-4 mm. The greatest height
in the males was 41 mm., the least was 28 mm., and the mean was
34 mm.; in the females the greatest height was 37 mm., the least
was 29 mm., and the mean was 33 mm.

The orbital index is obtained as follows :

orbital height x 100
orbital width ~

The index was computed in one hundred and twenty-five skulls, of
which eighty-four were men and forty-one were women. It ranged
from 73°7 to 105-1, and the mean was 86°4.

In grouping skulls in their orbital and nasal indices I have in this,
as in my previous craniological memoirs, adopted the terms employed
by Broca and Fiower, as well as their numerical divisions of the
groups. An orbit is said to be microseme when the height is low in
relation to the width and the index is below 84. Thirty-three skulls
came into this group. On the other hand, when the height and
width closely approximate so that the base is rounded and the index
is 89 and upwards, the orbit is megaseme, and to this group fifty-
seven specimens belonged, and in three of these the index was 100 or
upwards. Orbits are named mesoseme when the index is between 84
and 89, and thirty-three skulls fell into this category. In Scottish
skulls the rule was for the orbit to be high in relation to the width,
and somewhat rounded in outline, though exceptions not unfrequently
occurred. My observations on the orbital index in the skulls of
numerous races have satisfied me that it presents a great range of
variation in the same race, and that it possesses only a secondary
value as a race character.

Nasal Index.— The relation between the height of the nose,
measured from the nasion to the lower border of the apertura
pyriformis, and the greatest width of that aperture, constitutes one of

404 SIR WILLIAM TURNER.

the most important anthropological characters of the face. In eighty-
four male skulls the height ranged from 60 mm. to 46 mm., and the
mean was 53°5 mm.; in thirty-eight females the range was from
57 mm. to 44 mm., and the mean was 49°9 mm. In eighty-two
males the nasal width ranged from 28 mm. to 19 mm., and the mean
was 23:1 mm. In thirty-five females the range was from 26 mm. to
19 mm. with a mean of 22°1 mm. The nasal index expresses the
numerical relation between the width and height, and is computed
as follows, the height being = 100:

nasal width x 100
~ nasal height ~

The index was obtained in one hundred and _ twenty-three
specimens, eighty-one males and forty-two females. It ranged from
55°3 to 34:5; the mean was 42°5, and with few exceptions the height
was more than twice the width. If with Broca and Flower we
regard all skulls in which the nasal index is 53 and upwards as
platyrhine, ze. with the pyriform aperture wide in relation to the
height of the nose, only four specimens exhibited this character. On
the other hand, in ninety-three skulls the anterior nares were narrow
and elongated, and the nasal index below 48 was leptorhine, and in
fourteen of these specimens the index was below 40. The remaining
twenty-six skulls had the index ranging from 48 to 53 and formed an
intermediate or mesorhine group. The occurrence of wide nostrils in
the Scottish face may be regarded therefore as accidental, and due
perhaps to intermixture, through an ancestor, of a strain of some race
in which a platyrhine nose was an ethnic character. The four
platyrhine specimens were one in each of the East-Lothian, Mid-
Lothian, Highland and Dissecting-room groups. The customary form
of nose in Scotland is long, relatively narrow, with a well-marked
bridge, and projecting so that the type of face is prosopic, which
means that the nose distinetly projects beyond a line drawn between
the anterior part of the two malar bones,

Facial Indices,—An important character which has been systemati-
cally studied by KotiMann is the relation between the length and
breadth of the face in different crania.1 The length or height of the
entire face is measured from the nasion to the lower border of the
symphysis menti, whilst the breadth is between the most projecting
parts of the two zygomata. In twenty-one male skulls measured, the
longest face was 137 mm., the shortest was 104 mm., and the mean
was 120°7 mm.; in six females, the mean length was 108°. In
sixty-eight male skulls the greatest breadth was 144 mm., the least
was 117 mm., and the mean was 132°2 mm. In thirty female
skulls the greatest breadth was 135 mm., the least was 115 mm.,
and the mean was 121°5 mm. With one exception, in which the

length and breadth were equal, the breadth of the face exceeded ©
the length,

‘ Rassen Anatomie der europdischen Menschenschidel in Verhandl. der
Naturforschenden Gesellschaft in Basel, viii..Theil, 1 Heft. 1886,’

iar eT. i

GENERAL CHARACTERS. OF CRANIA OF PEOPLE OF SCOTLAND. 405

- A complete or nasio-mental facial index can be computed as follows :

nasio-mental length x 100
interzygomatic breadth *

As so frequently happens in craniological collections, the lower jaw
had been preserved in only a small number of the skulls, and the
complete facial index could only be taken in twenty-six specimens,
twenty-one males and five females; the mean of the series was 90:
that of the males was 92°3, that of the females 87°8.

Kotimann divides skulls and heads into two groups according to
the relation of the length to the breadth of the face. When the
index is 90-1 or upwards the face, he says, is leptoprosopic, high
(long) or narrow faced ; when the index is below 90-1 it is chame-
prosopic, low or broad faced. In the study of ‘the proportions
of the face, and in grouping skulls in accordance with their facial
indices, it is useful, as in the other relative proportions of the skull,
to have a group intermediate between the two more extreme forms,
We may appropriately speak, therefore, of a third or mesoprosopic
group, and include in it those skulls and heads in which the index
ranges from 85 to 90, both inclusive. The chameprosopic group
under this arrangement would consequently be limited to those
heads in which the index is below 85. In the series of Scottish
erania under consideration eighteen were leptoprosopic, four were
mesoprosopic, and only four were chameprosopic in my more
limited use of the term.

To obtain as far as possible an idea of the relation between the
length and breadth of the face in skulls where the lower jaw is
absent, Kottmann has suggested that the interzygomatic breadth
should be compared with the length of the superior maxilla
measured from the nasion to the alveolar point between the two
central incisors. Seventy-nine crania were measured in these
diameters, viz., fifty-six males and twenty-three females.

The male crania ranged in the maxillary length from 61 mm. to
$4, and the mean was 71-6 mm. The female crania ranged from 60
to 74 mm., and the mean was 67 mm. An index, which may
be appropriately named mazillo-facial, can be computed as follows :

nasiv-alveolar length x 100
interzygomatic breadth ~

The maxillo-facial index was taken in seventy-nine skulls, fifty-
five of which were males and twenty-four females. It ranged from
61°8 to 46°5, and the mean was 54°6.

In grouping ecrania under the maxillo-facial index, KoLuMANN
employs the same terms, leptoprosopic and chameprosopic, as in the
divisions of the complete facial index, but the numerical limits of the
two groups, owing to the length representing only a segment of the
complete face, are necessarily different. When the maxillo-facial
index is 50°1 and upwards, he regards it as leptoprosopic ; when 50
or less, it is chameprosopic. In this memoir I have retained the
numerical limit of the leptoprosopic group, and find that with seven

406 SIR WILLIAM TURNER.

exceptions all the skulls belonged to it, and that in five leptoprospic
specimens the index ranged from 60°3 to 61°8. If a division of the
chameprosopic group of KoLttMANN into mesoprosopic and chamee-
prosopic were adopted for the maxillo-facial as | have suggested for
the complete facial index, and 45 were taken as the lower numerical
limit of the mesoprosopie group, the seven exceptional skulls above
referred to would fall into that group. No skull, therefore, in its
maxillo-facial index was chameprosopic in this more restricted use of
that term, and the general type of the face in the Scottish crania is.
leptoprosopic.
The facial indices may be grouped as follows :

Complete facial.) Maxillo-facial.
Leptoprosopic, . . 90°1 and upwards, . . 50°l and upwards,
Mesoprosopic, . . 85 to 90,. ; ; . 45 to 50.
Chameeprosopic, . . below 85, ee: . below 45.

A low or chameeprosopic maxillo-facial index necessarily depends
on the upper jaw being short, in relation to the breadth of the
face, and to produce a chameprosopic complete facial index in both
the upper and lower jaws being relatively short. A relatively
short upper jaw necessarily also affects both the height of the nose
and the height of the orbit, so that one would expect to find a
chamzprosopic face associated with alow and possibly a platyrhine
nose and with a low or microseme orbit. The Scottish face is
therefore long and narrow in comparison with the broad, squat faces
in the Mongolian and some other types of head, In the Esquimaux,
for example, the mean interzygomatic diameter in eighteen males was
138°0 mm., whilst in the Scotsmen it was only 132°2 mm.

Palato-alveolar or Paluto-maxillary Index.—Anthropologists
concur in considering that the relations between the length and
breadth of the hard palate in the races of men should be enquired
into. Broca? and Vircnow ? limited the measurements in this region
to the hard palate itself, and computed an index which has been
named staphylin or palatal. FrLower‘ modified and improved these
measurements by including the alveolar arch, and computed an index
which he termed maxillary. In my Challenger Report® I suggested
that the terms palato-maxillary or palato-alveolar were to be preferred,
as expressing more fully the parts measured and the index which is.
computed from them. The length is taken from the alveolar point
to the midpoint of a line drawn between the hinder ends of the
alveolar borders, and the width is between the outer part of the alveolar
arch opposite the second upper molar tooth. The palato-alveolar

1 The complete or nasio-mental facial index corresponds, in the diameters from
which the index is computed, with the zygomatic facial index of. KoLLMANN,
The maxtlo-facial index corresponds with the upper facial index of KoLLMANN
in the points of measurements.

* Instructions craniologiques, p. 77.

® Archiv fiir Anthropologie, Bd. xv. s. 5, 1884.
sas ee Characters of Fiji Islanders,” Journ. Anthrop. Inst., November

° 1884, p. 7, and Jowrn, Anat. and Phys., vol. xvi. p. 135, October 1881.

oye i fen.3

GENERAL CHARACTERS OF CRANIA OF PEOPLE OF SCOTLAND, 407

length in fifty-five males ranged from 46 to 62 mm., and the mean was
55°6 mm. ; in twenty-eight females the range was from 45 to 59 mm.,
with a mean 51 mm. The palato-alveolar breadth in the males
ranged from 50 to 71 mm., and the mean was 60°9; in the females
the range was from 52 to 64 mm., with a mean of 58°3 mm.

The palato-alveolar index was computed as follows :

palato-alveolar breadth x 100
palato-alveolar length

In my Challenger Report I suggested that relatively long palato-
alveolar regions with an index below 110 should be named
dolichuranic ; relatively wide palates with an index above 115,
brachyuranic ; and those with an intermediate index between 110 and
115, mesuranic. As skulls exhibit, however, a wide range in the
index in this region, I now make the further suggestion that when the

_ index falls below 105 it should be called hyperdolichuranic ; where
it exceeds 120, hyperbrachyuranfc. The divisions of the group may
be aes gga in tabular form as follows :

= cemygege ‘ ; : e . below 105.
Dolichuraniec, . F : : ¢ . 105 to 110.

Mesuranic, . 4 4 A : . 110 to 115.
Brachyuranie, . m - ; ~ 2 . 115 to 120.
Hyperbrachyuranic, : 3 ; F . above 120.

In this series of Scottish skulls nineteen were hyperbrachyuranic ;
seventeen were brachyuranic ; fifteen were mesuranic ; twenty were
dolichuranic ; and eleven were hyperdolichuranic. In only three -
specimens, two females and a male, was the length greater than the
breadth ; but in twenty-eight skulls the length was considerable in
relation to the breadth, though not greater, so that the palate had
an elongated appearance. As a rule, however, the breadth of the
region was materially greater than the length, and the form of the
palato-alveolar arch was that of a wide horseshoe.

Lower Jaw.—This bone had been preserved in only thirty-five
skulls, twenty-six of which were males. In several of these, many
teeth had been lost during life and their alveoli absorbed, so that the
form of the bone had been more or less modified. Where the teeth
had been in great part preserved, the body of the jaw had in the male
sex a vertical diameter at the symphysis, ranging from 26 to 37 mm.,
and with a well-defined chin ; the ascending ramus was broad and the
angle was pronounced. The entire jaw had in most specimens a
massive appearance, which had materially contributed to give
character to the face, and from the marked vertical diameter of the
body of the bone had constituted an important factor in giving to the
entire face a length which placed it distinctly in the leptoprosopic
group. The condyloid and coronoid diamaters of the jaws varied
in relative length in the series: in seventeen specimens the height
from the angle to the top of the condyl was greater than to the tip of
the coronoid, whilst in thirteen the coronoid height was longer, and in
three specimens they were equal. The intergonial width ranged in
the male jaws from 88 to 114 mm., and the mean of twenty-four

408 GENERAL CHARACTERS OF CRANIA OF PEOPLE OF SCOTLAND:

specimens was 100 mm., a diameter between the angles of the jaw
materially below the interzygomatic, intermalar and _ stephanic
breadths, but distinctly higher than the minimum frontal diameter. —

To assist the reader in obtaining a bird’s-eye view of the
dimensions and proportions of the constituent parts of the Scottish
skulls studied in this memoir, I have prepared Table XVI., in which
I have stated for both sexes the maximum and minimum dimensions,
as well as the mean of the principal measurements in the series of
skulls, together with the maximum, minimum and mean of the
the respective indices. I have also, by way of comparison,
included in the Table the mean diameters and indices of a number of
skulls of male aboriginal Australians which I have measured.

TaBLe XVI.
4
Scottish Skulls Australians
Females. Males, Males.
Max. | Min. |Mean.} Max. | Min. | Mean Mean.
Cubic capacity, . 1625 {1100 |1322 {1855 |1230 |1478 1280
Glabello-occipital length, 193 | 161 | 1787| 204 | 167 | 186°6 191°3
Basi-bregmatic sc 140 | 118 | 126 | 145 | 117 | 132°4 135
Vertical index, . | 776) 64 70°5| 794| 637) 709 70°6
Greatest parieto- squamous
breadth, i . - | 153 | 128 | 188 | 159 | 130 | 149° 132
Cephalic index, ‘ : 87'9| 693) 772) 872) 682) T7H4 69°
Horizontal cireumference, . . | 550 | 470 | 506 | 572 | 490 | 5381 530
Vertical transverse circum-
ference, . 459 | 381 | 409°6| 464 | 398 | 434 rf
Basi-nasal length, . | 105 86 95°3| 110 91 | 101°4 a
Basi-alveolar length, . . | 102 79 91 | 108 81 96 ae
Gnathic index, : 100° | 86°7| 948)| 103°2| 83 | 9465 100°6
Total longitudinal circum-
ference, . 587 | 441 | 488°8| 559 | 468 | 513°2 dee
Interzygomatic breadth, 135. | 115 | 121°5| 144 | 117 | 1822 498
Nasio-mental length, 114 | 102 | 1088) 137 | 104 | 1207 Ss
Complete facial index, 92°2| 825| 87:8| 100° 79'3| 923 aS
Nasio-alveolar length, 74 60 67 84 61 716 s
Maziilo-facial index, . 61'8| 48° | 55'1| 608) 465| 543 oes
Nasal height, 57 44 49°9| 60 46 53°5 sas
Nasal width, 26 19 22°1| 28 19 23°1 ans
Nasal index, 54 845| 444| 853) 37:9) 389 b7°
Orbital width, 41 35 37°4| 46 35 39 pi
Orbital height, . 37 29 33 41 28 34 ae
Orbital index, 1028| 73°7| 846\ 1051) 769) 872 818
Palato-alveolar length, 59 45 51 62 46 55°6 ony
Palato-alveolar breadth, 64 52 58°3| 71 50 60°9 uh
| Palato-alveolar index, 130°6| 945) 1098 | 130° 98°2| 113° 109°

ee 6 eee ee

INDEX.

AnchoLociA Anatomica (hilum), 293,
Australian, skeleton of, 89.

Barratt, J. O. Wakelin, dilated
. cerebral ventricles, 150, 347. 1
Bradley, Prof. O. Charnock, develop-
ment of cerebellar fissures, Part I.,
112 ; Part II., 221. 4 ;
Brain, relation of its deeper parts to
the surface, 241. :

Broad, W. H., skeleton. of native
Australian, 89, :
Broom, R., 7 or aca in
ilia, 107.

Burne R. H., cerebrum of micro-

cephalic idiot, 258,

CARDIOGRAPHIC tracings from base of
“human heart, 41. . i:
Carmichael, E. Scott, position of gall-

bladder, 70.
Carotid canal, rudimentary condition

of, 362.
Cephalometric data bearing on relation

of size of, and shape of head to

mental ability, 333. :
Cerebellum, development of fissures of,

Part I., 112; Part II., 221.

en notes on the morphology of,

Cerebral cortex in a case of congenital
absence of the left upper limb, 46.
ventricles, form -.of, in chronic

brain atrophy, 150..
Clarke, Astley V., cardiographiec trac-
ings, 41.
Crania of Scottish people, 392. )
Cranial contents, are they displaced by
freezing the head? 97.

Di.arep cerebral ventricles in chronic
brain atrophy, 347.

Epeewourn, development of head. |

museles in Seyllium Canicula, 73.
Eppes of the pelvis, the meaning
of, 315.

VOL. XXXVI. (N'S. VOL. XVII.)—JULY 1903.

|

|
|

FEATHER bifurcation, case of, 368.

GALL-BLADDER, position in human sub-
ject, 70.

Gaskell, Walter H., origin of verte-
brates, 168.

Gladstone, R. J., cephalometric data
bearing on relation of size and shape
of head to mental ability, 333.

Gray, Albert .A,, method of preparing

membranous labyrinth, 379.

| Griffith, Prof. T. Wardrop, malforma-

tion of-tricuspid valve, 251.

division of left auricle into two
compartments, 255.

Gyrus hippocampi, 324.

Hatt, H. §., absence of superficial
flexors of the thumb, 287.

Handley, W. Sampson, method of .ob-
taining uniplanar sections with the
rocking microtome, 290.

Head muscles in Seyllium Canicula,

development of, 73.

Hearts showing abnormalities of great
veins, 382. ,

‘Hilum, archeologia anatomica, 293.

A j

JamiEson, Edward B.,. anomalies in
,herves arising from lumbar plexus,
etc., 266. ;

Kerru, Arthur, posterior segments of
_ body; extent to, which they have
been transmuted, 18.

Laiptaw, P. P., peculiar features in a
temporal bone, 364.

Left auricle, division into two com-

, partments, 255.

MACALISTER, Prof... A., arecheologia

anatomica, 293.
Macalister, G. H. K., rudimentary
condition of carotid canal, 362,
Macnamara, N. C,, cerebrum of micro-
cephalic idiot, 258.
28

410

Membranous labyrinth, method of pre-
paring, 379.

Microcephalic idiot, cerebrum of, 258.

Moorhead, T. G., cerebral cortex in
case of congenital absence of left
upper limb, 46.

Nasarro, David, two hearts showing
peculiarities of great veins, 382.
Nerves, anomalies in, ete., 266.

OrIGIN of vertebrates, 168.

PanornEAs of Teleostei,
islet ” in, 375.

Parsons, F, G., meaning of epiphyses
of pelvis, 315.

ericardium, early stages of develop-
ment of, 1.

Posterior segments of the body ; extent
to which they have been transmuted
in evolution of man and _ allied
primates, 18.

Pterygo-quadrate arch in Lacertilia,
development of, 107.

** principal

Rennikg, John, ‘‘ principal islet” in
pancreas of Teleostei, 375.

Robertson, Prof, Arthur, development
of pericardium, 1.

Rutherfurd, W. J., feather-bifurcation,
368.

luinbar vertebrae of

SAcRAL and

INDEX.

Australian aborigines, abnormalities
of, 359.

Scotland, crania of people of, 392.

Shepherd, R. K., form of human
spleen, 50,

Smith, Prof. Elliot, the so-called
yrs Late 324,

notes on the morphology of
the cerebellum, 329.

Smith, Dr W. Ramsay, abnormalities
in sacral and lumbar vertebre of
Australian aborigines, 359.

Spleen, form of human, 50,

Symington, Prof. Johnson, Are the —
cranial contents displaced and the
brain damaged by freezing the entire
head ? 97.

the relations of the deeper

parts of the brain to the surface, 241,

TEETH in mammalia, evolution of, 131.

Temporal bone, peculiar features in a,
364,

Teratology, literature of, 298.

Thumb, absence of superficial flexors
of, 287.

Tims, H. W. Marett, evolution of
teeth, 131.

Tricuspid valve, malformation of, 251.

‘Turner, Sir William, ecrania of the
people of Sotland, 392.

Windle, Prof. B. C. A., report on
teratological literature, 298.

PROCEEDINGS OF THE

ANATOMICAL SOCIETY OF GREAT BRITAIN
AND IRELAND.

JULY 1902.

THe Summer Meeting of the Anatomical Society of Great Britain
and Ireland was held in the Medical School of St Bartholomew’s
Hospital, E.C., on Thursday the 3rd and Friday the 4th of July 1902.
The President, Mr C. B. Locxwoop, occupied the chair. On
Thursday the meeting commenced at 3 p.m. and lasted until 5.15 p.m. ;
twenty-seven members and four visitors were present. On Friday
the meeting commenced at 3 p.m. and lasted until 5.30 p.m.; twenty-
four members and two visitors were present, Letters regretting
inability to attend were received from Prof. A. H. Youne, Prof.
Muscrove, Dr Bryce, and others.

The minutes of the last meeting were read and confirmed.
The following communications were made :—

(1) Dr R. J. A. Berry showed two cases of twin monsters (females),
both of which had occurred in the practice of Dr F. W. N. Hautrary,
Edinburgh.

1. In the first case the twins were full term and well developed. |
The line of fusion was along the anterior abdominal wall, from the
ensiform process to rather below the umbilicus. Subsequent dis-
section showed the twins to be normal in every respect with the
following exceptions :—

___ (a) The two stomachs are united by a single duodenal tube, from

the centre of which proceeds a single jejunum common to both twins ;
this single jejunum subsequently divides into an ileum for each twin,
the large intestine of each of which is perfectly normal.

(b) There is a single liver, placed astride the single duodenum in
such a way as to appear as though it were bifurcated. The gall-
bladder is absent.

(c) There is a single pancreas common to both twins, and only one
spleen.

°°. In the second case the line of fusion is more extensive, including
the thoracic wall as well as the abdominal wall. The left upper limb
of the right twin is fused with the right upper limb of the a twin,

lxii PROCEEDINGS OF THE

with the exceptions of the two hands of these limbs which remain
separate, The following peculiarities are present :—

(a) The alimentary canal is precisely similar te that of the first
case, but a Meckel’s diverticulum is present.

(b) The liver resembles that of the first case, but a gall-bladder is
present.

(c) There is only one pancreas and one spleen, as in the first case.

(7) There isa single heart, giving off a right-sided aorta for the
right twin and a left aorta for the left twin.

(e) The inferior vene cavee of the two twins fuse together in the
substance of the single liver to form a single vessel which opens into
the single right auricle.

(7) There are two superior vene cave, which open into the single
auricle.

(2) Flexor Carpi Radialis of Elephant, showing great development of
elastic tissue. By Mr R. H. Burns, B.A.

This specimen, exhibited by the kind permission of Professor
Srewart, is a transverse section through the flexor carpi radialis of
an Indian elephant. The muscle tissue has been partly dissected away
to show in relief a strong development of elastic tissue in the peri-
mysium.

This tissue forms a thick layer upon the exposed surface of the
muscle, connected with elastic bands and sheets of various sizes run-
ning between the muscle bundles.

Towards the distal end of the muscle these elastic bands converge
towards the superficial sheet, and the latter, suddenly assuming a
tendinous character, becomes the proximal part of the tendon of
insertion of the muscle.

A similar but less marked development of elastic tissue between
the muscle bundles was observed in another fore-limb muscle
(probably the flexor profundus), but the beast was fleshed before we
saw it.

The flexor carpi-radialis of the elephant is described by Miall and
Greenwood in the Journal of Anatomy for 1878, and this develop-
ment of elastic tissue noticed.

They speak of the muscle as formed of “alternate layers of muscle
and elastic tissue in about equal proportions”—a description not
strictly applicable to this specimen.

With regard to the probable use of this elastic muscle to the creature,
Miall and Greenwood make the following remarks :—

“This... . peculiarity would give rigidity to the limb when
extended in a ‘perfectly straight line. When the animal stands the
toes are over-extended so that the flexor carpi radialis, stretched /ike
the chord across an arc, tends to draw the carpus upwards and for-
wards, and opposes the flexors. When, on the other hand, flexion has
carried the limb beyond the neutral line, the elastic band assists es
flexors, drawing the carpus upwards and backwards.”

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xiii

From the position of the muscle in the limb, and its insertion upon the

Elastic tissue

Elastic tissue

Fic, 1.—Distal end of flexor carpi radialis of the Indian elephant, seen from
the deep aspect ; muscle bundles partly dissected away on right side to show
elastic tissue.

Fic, 2.*—Diagram of transverse section through upper part of flexor carpi
radialis of Elephas indicus ; elastic tissue black,

posterior surface of the carpus, it does not seem that such an action in aid
of extension, as suggested by Miall and Greenwood, could possibly occur.

* From a block kindly lent by the Royal College of Surgeons of England.

lxiv . PROCEEDINGS OF THE

Rather one would ‘suppose that this tissue would tend to passively
prevent over-extension when standing, and perhaps even more would
obviate risk of rupture of the muscle under the severe strain put upon
it when, in running, the flexor muscles have the vast weight of the
creature suddenly thrown upon them.

(3) Mr R. C. Battey showed a band formed by the persistence of
an obliterated vitelline artery. The specimen was taken from the
body of an adult male subject in the dissecting-room of the Medical
School of St Bartholomew’s Hospital. On opening the abdomen a
strong band was seen running up to the umbilicus, which on further
dissection was found to consist of a fibrous cord, which started from
the right side of one of the lower branches of the superior mesenteric
artery to the ileum, about a quarter of an inch from the main vessel.
It then turned towards the right, crossing in front of the superior
mesenteric vein, and lying between the layers of the mesentery. It

ae wea
% A i yl
ea) [idelyy [yds ihe
Wy.

\ alles
wy
UZARG ED

Band formed by obliterated remains of the vitelline artery. The anterior
abdominal wall is reflected to the right.

crossed the ileo-cecal junction, being bound down to both these
portions of the intestine by the peritoneum, which it raised in a
fold.

It then appeared as a free rounded cord, covered by a tube of the
serous membrane ; and as it passed up to the navel it pierced the great
omentum, just above its free edge, through a rounded ring-like
aperture. It was finally lost on the back of the anterior abdominal
wall in two peritoneal folds which passed up to the umbilicus.

|

ee atl
Se a ye
; t

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. lxv

- The cord was undoubtedly the remains of a vitelline artery, and it

is interesting to note that there was no trace of a Meckel’s diverti-
culum in connection with it. Another interesting point about the
‘structure is the way in which it passed through the peritoneum so as
to form a free band while still retaining a complete investment from
it,—a band so free, in fact, that intestine might easily have been kinked
round it, and so strangulated.

(4) Dr Davtp Naxparro showed two hearts with peculiarities of the
great veins. In one, the four pulmonary veins entered the right
auricle through a large coronary sinus; the other showed a persistent
duet of Cuvier (left superior vena cava) which was joined by a left
hepatic vein at its entry into the coronary sinus.

A full account of this communication will appear subsequently in
the Journal of Anatomy and Physiology.

(5) Professor J. Symineron showed a number of beautiful pre-
parations, photographs, and lantern slides to illustrate the relation of
the deeper parts of the brain to the surface.

(6) Mr Kzirn showed a number of lantern slides demonstrating the
extent to which distal segments of the body have been transmuted in the
genera of the higher primates during their evolution. Mr Keith
divided the primates into two groups—the pronograde and ortho-
grade,—the latter group containing the anthropoids and man. The
pronograde form he assumed to be the primitive type, and accepted
extant genera such as Cebus and Semnopithecus as approximate
representatives, as far as the number and arrangement of their body
segments was concerned, of the Miocene pronograde apes, from which
the orthograde was evolved.

In the evolution of the gibbon, the best living representative of the
early orthograde form, the caudal vertebrae became amorphous, the
depressor muscles of the tail formed a muscular pelvic floor, the 26th
segment, instead of being lumbar, became sacral, the origin of the
sacral and lumbar nerves was shifted one segment forwards, and the
number of sternal ribs reduced.

With the evolution from the early orthograde or gibbon type of
the giant orthograde primates—the orang, chimpanzee, gorilla and
man—there was a further transmutation forwards, involving a segment
or more. Some of the distal caudal vertebrae and nerves were
suppressed ; the 25th (lumbar) segment became sacral, the sacral and
lumbar nerves were moved forwards in their points of origin.

The statistics and diagrams on which these deductions are based
are published in the Journal of Anatomy and Physiology for October
1902.

(7) Mr N. Bishop Harman, who had arranged to exhibit a child
possessing the minimal form of fissura facialis, was obliged to
postpone the demonstration of the case on account of the patient’s
illness. He showed instead a drawing of the abnormality, which

lxvi PROCEEDINGS OF THE

illustrated the two small recesses in the skin on each side of the face
in the vertical lines of the caruncule, on the right about 3 mm.
below, and on the left about 6 mm. below the same. Mr Harman
said that the right hole would admit the smallest lachrymal probe
(Couper’s No. 1) 3 to 4 mm., the left hole would only admit a
bristle for a lesser distance. The recesses appeafed to have no
communication with the lachrymal ducts. It is intended to show the
child at a subsequent meeting. ;

(8) Professor C. J. Parren made a preliminary communication on
some points on the topographical anatomy of the thoracic and abdomi-
nal viscera of Hylobates haianus (hainan gibbon), The animal was first.
thoroughly hardened by intra-vascular injections of formalin. The
form of the various viscera, which closely resemble those of man, was
described. But the paper dealt chiefly with the position of the viscera
relative to the vertebral column. Besides the actual specimens, two
models were exhibited, one of the entire trunk, showing the position
of the organs to the vertebral column and ribs; the other, of the
duodenum, pancreas, kidneys, adrenals, and spleen, illustrating their
form and relations to one another.--This paper will be published 7
extenso at a later date.

(9) Professor A. Francis Dixon exhibited the skull and some of the
long bones from a case of acromegaly. In height the individual from
whom they were taken was 6 feet 24 inches The skull showed in a
typical manner great elongation of the fave, associated with enormous.
development of the lower jaw and of the maxilla. The pituitary
fossa was much enlarged, the surrounding bone, owing to absorption,
being very thin. The origins of the temporal muscles were very
extensive, the upper limits of the temporal fosse of opposite sides.
approaching to within 28 mm. of one another. The articular surfaces.
of the long bones were irregular, and exhibited marked arthritic
changes.

(10) Professor ARTHUR Roprnson read a paper on the preliminary
stages of the development of the pericardium. The paper, which is

published in extenso in the October number of the Journal of

Anatomy and Physiology, may be summarised as follows :—

1. In Amputpians the pericardium is formed by the fusion of the
anterior parts of the lateral halves of the cclom in the ventral
middle line beneath the anterior part of the foregut, and a ventral
mesocardium is present for a time.

2. In Brrps the pericardium is formed after the development of
the head fold by the ingrowth of the lateral parts of the ccelom into-
the ventral wall of the foregut and their fusion in the middle line.
The rudiments of the heart lie along the dorsal part of the line of
fusion, and for a time a ventral mesocardium is present.

3. In Mammats the pericardial mesoderm is present in the
pericardial portion of the embryonic area, and it is completely
separated into somatic and splanchnic layers before the head fold

:
.

in i ies ei ill

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. Ixvii

appears ; there is therefore a single pericardial cavity, which extends
from side to side along the anterior boundary of the embryonic area.
As the head fold forms, the pericardial region is reversed, and it is
carried into the ventral wall of the foregut, where it forms a U-shaped
tube, which communicates at each end with the general ccelom.

The rudiments of the heart are formed in the splanchnic layer of
the pericardial mesoderm ; therefore, after the reversal of the area,

_ they lie in the dorsal wall of the pericardial space, attached by a

dorsal mesentery to the ventral wall of the foregut; but they are
never at any time connected with the ventral wall of the pericardium
by a ventral mesocardium. :

(11) The Sternal Angle in Man. By Waurer Kipp, M.D.

_ The adult human sternum presents almost constantly an angle
which may be observed through the soft tissues, unless there be an
unusual amount of fat or the thorax be an ill-developed one, and it is
situated at the junction of the manubrium with the body of the
sternum. A projection corresponding to this angle is found along the
second costal cartilage and the adjoining portion of the second rib on
each side. In a few cases a similar but less pronounced angle is seen
at the level of the third costal cartilages. The joint between the
manubrium and the’ body of the sternum constitutes the true sternal
angle, and the latter appears! to be formed by the deposition of bone
on the anterior surface of the joint. The sternal angle corresponds
to those transverse lines of junction between the segments of the
body of the sternum, the first of which forms the occasional second
sternal angle. It is only in advanced age that complete ankylosis
takes place in this joint, and therefore much later in life than the
other segments become fused.

The sternal angle is sufficiently prominent to have been carefully
noted and represented by the sculptors of antiquity, as may be seen
in most of the statues in such galleries as those of Rome and Florence,
and a very few of these show also the second sternal angle, to which
reference has been made. A fairly well-defined angle is present in
the sterna of the gorilla, chimpanzee, and orang, and of these genera
of apes the chimpanzee shows it in the most marked degree.

Such a break as this in the even contour of the sternum must have
some mechanical origin, and it seems most probable that it is con-
nected with the difference shown by the first two ribs on the one
hand, and the remaining true ribs on the other, as regards their
respective directions of movement in respiration. The nearly trans-
verse position of the two first ribs, and consequently smaller degree
of rotation, is compensated for by the raising of the sternum in
inspiration, which necessarily affects the movement of these ribs more

+ “The Varieties of Ankylosis by Bone in different parts of the Skeleton,”
Joseph Griffiths, M.A., M.D., F.R.C.S., The Journal of Pathology and
Bacteriology, Edinburgh and London, p. 318.

lxviii PROCEEDINGS OF THE

than the others, and greater freedom of movement is afforded to
them by the pre-mesosternal joint. In this view of the sternal angle
the advantage conferred by the very late ankylosis of this joint is
recognised, and it may be looked upon as a critical level in the thorax,
marking the spot where the expansion of the chest-wall changes
slightly but definitely from one plane to another. This is recognised
superficially and roughly by placing the chest-piece of a straight
stethoscope on the second costal cartilage while the person examined
is breathing deeply, and then on the third cartilage, when the direc-
tion taken by the ear-piece is clearly seen to bend upwards in the
former case, and either horizontally or downwards in the latter.

The attachments of some of the extrinsic muscles of respiration
round and about this sternal angle bears out the same view of its
production, for, on the one hand, there are the three strong scaleni
muscles elevating and fixing the first two ribs, and on the other, the
triangularis sterni, inserted into the cartilages of the sixth, fifth,
fourth, and third ribs, and slightly and variably into those of the second
and first ribs, depressing the respective costal cartilages. This is an
arrangement of muscles grouped round the sternal angle, pulling very
much in opposite directions, so that the anatomical conditions caleu-
lated to keep up the movement of the joint under consideration later
than in the rest of the sternum are present.

These simple anatomical statements have been made because they
are necessary to the particular point dealt with here.

In Nature, Feb. 13, 1902, I recorded two cases of persons, aged
28 and 33, with especially smooth, hairless skins, who presented
certain isolated hairs standing out from the skin with remarkably
persistent direction. In one case there were two long hairs, each an
inch and a half in length, just above the sternal angle pointing up-
wards towards the neck; in the,other case there were three hairs,
each an inch long, pointing downwards, and situated just below the
sternal angle. The only interest in these two cases is the fact that a
few stray hairs, separated from one another in position by less than
the breadth of a costal cartilage, can maintain their original and
divergent directions with such persistence. These two cases corre-
spond exactly with what is found by a simple study of the hair
streams on the pectoral region (see figure), The arrangement is re-
markable, and confined, as I believe, to mam alone. At the level of
the sternal angle there occurs a division of the hair-streams, by which
one pursues its normal and ancestral course down the sternal groove
and over the pectoral muscles, and the other stream divides from it
at the level of the sternal angle, and passes vertically upwards to the
neck in the middle line, and over the clavicles it slopes towards the
middle line till it reaches the level of the upper border of the larynx,
where its course need not be pursued,

An arrangement of hair so peculiar as this at the level of the
sternal angle (which I may repeat is not shared by any other animal
possessing a sternal angle) is almost certainly connected with the
function of respiration in some way or other. But inasmuch as this
hair arrangement is not found in man’s nearest existing congeners,

eT

ee

an although they too possess a sternal angle, some other etiological
factor must be sought for it. I would suggest that the effect of the

pressure of clothing on the underlying skin is competent to produce

6 ; - this change in the direction of the hair, and that probably it is the

efficient cause. During inspiration in the sitting and standing
postures, or in locomotion, the weight and friction of clothing on the
upper portion of the chest-wall clearly tends to pull on the ever-
growing stream of hair, drawing it over the sternum upwards, and
in the subclavicular region upwards and towards the middle line.
In expiration the chest-wall is almost entirely removed from any

pressure or friction of clothing, so that any reverse action on the
hair-stream, which might be supposed to be exercised by expiration,
does not take place. Below the joint which forms the sternal angle

the changing direction of the ribs during respiration is not calculated

in the same degree to draw the stream of hair upwards and contrary
to its ancestral trend.

[Wiedersheim touches on this subject in his Structure of Man,
translated by H. and M. Bernard, 1895, pp. 22, 23, 24, 25, which I
had not seen at the time of writing this paper. He there refers the
whorls found on the pectoral region of man to the supernumerary

lxx PROCEEDINGS OF THE

teats occasionally found above the normal mamma, and quotes two
cases from Herr Otto Ammon, one with a single pair and the other
with three pairs of supernumerary teats. The former showed these
whorls in the region of the teats above the normal mamma, but
Wiedersheim makes the significant admission that those below that
situation do not form vortices. This is exactly what would be ex-
pected, for the arrangement which I have indicated is simply the
normal one found in all persons who are sufficiently hairy. It has
nothing to do with supernumerary teats. |

(12) Professor A. MacpHart demonstrated a case of rudimentary first
dorsal ribs which had been brought under his notice in the dissecting-

room of the University of Glasgow. The macerated vertebral -

column with the abnormal ribs articulated, the second pair of ribs,
the sternum, and two drawings (figs. 3 and 4) illustrating the condition
of the soft parts, were exhibited.

The subject was an adult male Kaffir, in all other respects of a very
well developed type. The clavicles had been disarticulated and the

Fic, 1.—Sternum with second and vestigial first costal cartilages attached. _

costal cartilages cut through for the removal of the sternum before
the abnormal condition of the first arch had been observed, so that it
was impossible to determine accurately the relations of a vestige of
that arch in connection with the manubrium sterni on each side.
This seemed to take the form of an irregular block of partly ossified
cartilage, to which the subclavius muscle was partly attached, and

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ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. I1xxi

which deepened the clavicular surface of the sternum on its external
and inferior aspect. The maceration of the specimen in sand
destroyed the cartilaginous part of these blocks, leaving, however, a
small ossified mass on each side, which, on being connected to the
sternum beneath the clavicular surfaces, gave a complete transverse
measurement of 10°5 cm. to the bone at that part. The inner end of
each clavicle, corresponding to this increased surface, is likewise
enlarged, measuring 3°5 cm. in an oblique antero-posterior direction ;
this abnormal extent of the sternal end of the clavicle is gained
principally by a somewhat hook-shaped projection of the articular
surface downwards and backwards, and this part was found, in the
recent condition, to rest against the vestige of the first costal arch
described above, which, thus modified, has increased the strength of
the sterno-clavicular articulation.

The following points were noted in the relations of the soft parts
before maceration :—

The tendon of the subclavius muscle on each side was principally

Fic. 2.—Sternal end of left clavicle.

attached to the tip of the sécond rib and its cartilage, but was also
connected by means of strong fibrous tissue to the ‘ vestigial ’ cartilage
of the sterno-clavicular articulation.

The anterior extremity of the lst rib presented as a pointed process
among the fibres of the scalene muscles, and there was no trace of any
fibrous band continuing its direction forwards, suchas has been described
in other records of similar abnormalities. The right rib being con-
siderably larger than the left, it reached a lower level in the neck, and
was placed beneath the arch of the subclavian artery, while the
extremity of the left rib was situated immediately above the level of
the highest point of the arch.

On the right side only some fibres of the scalene group lay in front
of the artery in the position of the scalenus anticus ; these arose
from the anterior tubercle of the 6th cervical vertebra, and passed
down as a thin slip in front of the artery, to be inserted into the
outer (upper) surface of the second rib: a slight pointed tubercle
marks this attachment in the macerated specimen. A slip similar in

poewetecsnemmins

} et tee Bing

ay

Ixxil PROCEEDINGS OF THE

origin was present on the left side, and was traced downwards behind
the artery to the second rib,

A few tendinous slips arising from the anterior tubercles of the 3rd,
4th and 5th c.v. formed a thin sheet passing to be inserted into the tip
of the lst rib on each side, while the rest of the scalene mass arising
from the posterior tubercles of the lower cervical vertebree formed a
muscular sheet, partly inserted into the rudimentary first rib, but
mostly into the upper surface of the second.

A fan-like sheet of muscle radiating from the tip of the Ist rib and
inserted into the upper surface of the 2nd rib represented the external
intercostal muscle of the first space. There was no trace of an in-

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EXTREMITY —

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First Rie

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Fie. 3.

ternal intercostal muscle ; in its place on the right side there was a
well marked membranous sheet, with some aponeurotic fibres joining
the first to the second rib.

The anterior extremity of the first rib on each side was bound to
the second by a cone-shaped ligament, extending almost transversely
outwards, and overlapping the external intercostal sheet.

The cords of the brachial plexus were normal on both sides as
regards contributing nerves; the lower cord lay immediately behind
the subclavian artery on the right side, while the corresponding cord
on the left was displaced upwards by the projecting extremity of the
first rib, and was separated by it to some extent from the artery. In

___- ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. lxxiii

____ addition to the vestigial cartilage at the sterno-clavicular articulation,
_ seven costal cartilages articulated with the sternum: the cartilages of
_ the second arch were more obliquely placed than normal, particularly
_ that of the right side; the cartilages of the eighth arch thin at their
_ extremities, and to a large extent united to those of the seventh, were
___ traced to the margin of the sternum.

"bee ae me nr 8 meee

Fic, 4,

After maceration the following measurements were made :—
_ First Rib: Right—-Entire length 5 cm. ; length from inner edge
' of head to outer edge of tubercle 3°5 cm.; breadth
at tubercle 2 cm.
x Left—Entire length 3°5 cm.; length from head to
a. tubercle 3 cm.; breadth at tubercle 2 cm.
(The transverse processes of the first dorsal ver-
tebra showed a corresponding difference in length.)
Second Rib: Right—Length from head to tubercle 3 cm. ; length
from tubercle to anterior extremity 15°2 em.;
greatest transverse breadth 2°5 cm.
Left-—-Length from head to tubercle 2°6 cm. ;
length from tubercle to anterior extremity 4
em.; greatest transverse breadth 2°3 em,

lxxiv PROCEEDINGS OF THE

Both these ribs lie more horizontally than a normal second
pair and their shafts are distinctly flattened, resembling, both
in position and shape, an enlarged first pair. The transverse
diameter of the upper opening of the thorax measured
(approximately) 18 cm.

A full account of the bibliography connected with this condition
was published in the Proceedings of the Society, May 1900, by Phillips ;
this appears to be the sixth case of the kind recorded in Britain.

(13) Mr R. K. Suepuerp, B.Sc., read a communication on “ The
Form of the Human Spleen.” The paper is published 7m extenso in
the October number of the Jowrnal of Anatomy and Physiology.

(14) At the meeting of the Society held at Charing Cross Hospital
Medical School on Friday May 9th, Dr C. Appison showed three
museum preparations to illustrate the method of preparing
specimens by immersing them for various periods in a solution of
bleaching powder, to bring out with more distinctuess ligamentous
and fibrous structures, :

Dr Addison also showed a specimen taken from a dissecting-room
subject which presented a cervical rib on each side. The subject was a
female et. 56.

There were twelve thoracic ribs, the 12th rib on each side being
much reduced in size. The cervical ribs articulated with the body of
the 7th cervical vertebra, and with the posterior segment of the
transverse processes in the manner usually described.

From the head of the tubercle the cervical ribs measured 25 cm.
and 2°7 em. on the right and left sides respectively. From the
tubercle each rib arched forward parallel with the first thoracic rib,
and gradually narrowed to a blunt point, measuring from the tubercle
to the extremity along the outer border 3°5 cm. and 7°5 cm. on the
right and left sides respectively.

From the extremity of each cervical rib a fibrous cord (measuring
5°5 cm. and 4 em. on the right and left sides respectively) was pro-
longed forwards to a bony projection which extended outwards from
the first piece of the sternum below the clavicular articulation, and
which, in a large measure, as shown in the diagram, occupied the
usual position of the sternal end of the first thoracic arch. This
projecting piece of the sternum measured 3 cm. on the right side
and | cm. on the left from the outer margin of the clavicular articula-
tion. It presented the most unusual feature of the case, and is
especially interesting in regard to the possible development of the
sternum in conjunction with the costal arches,

The sterno-clavicular articulation was normal on both sides, with
well developed inter-articular fibro-cartilages. The first thoracic rib
had a costal cartilage commencing about the usual place, which at its
sternal extremity was not embedded into the manubrium sterni as
usual, but articulated, with a synovial joint, with the lower surface of

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. lxxv

the bony process projecting from the sternum, and the costal cartilage
gradually tapered to a blunt point at its sternal end.

The musculature of the specimen did not differ materially from
other recorded cases, Between the cervical costal arch, made up of
the rib and fibrous cord on each side, and the first thoracic rib there
were well marked external and internal intercostal muscles and a
small sub-costal muscle on each side in series with the rest,

The scalenus anticus on the left side was inserted into the upper
border of the cervical rib near its tip, and on the right side for 1°5
em. into the fibrous cord springing from the cervical rib, and for
‘5 em. into the tip of the rib itself, which, it will be remembered,
was smaller than on the left side. Behind the scalenus anticus on
each side the subclavian artery and the lowest cord of the brachial

Cervicas Rig,

Groove.

Seacequg
AnTievs.

15" Taoracte Rig.

STeRwa Process.

plexus grooved the upper surface of the additional rib, The front
part of the scalenus medius on each side was inserted into the upper
surface of the cervical rib from the groove in front to the tubercle
behind, whilst the back part of the muscle terminated in the inter-
costal tissues between the cervical and first thoracic ribs, with a
fibrous extension downwards to the upper border of the first thoracic
rib. The scalenus posticus was wholly inserted into the outer
surface of the first thoracic rib on the left side. On the right side it
was partly attached to the first thoracic rib and partly prolonged
across the first thoracic intercostal space to the upper border of the
second thoracic rib.

There was no abnormality in the arrangement of the subclavian

Ixxvi ANATOMICAL SOCIETY pene alee a

arteries or their branches, or of the cleapelnals
relations to the scalene muscles. —

Unfortunately, at a late stage of: the idiekeobion it
prolonged from the left cervical rib was cut away, and
of the additional eeonsssnecareon eee ‘icv
be worked out. ash Ls}

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PROCEEDINGS OF THE

ANATOMICAL SOCIETY OF GREAT BRITAIN
AND IRELAND.

NOVEMBER 1902.

Tue Annual General Meeting of the Society was held at King’s
College, Strand, W.C., on Friday, November 14th, at 4 pm. The
President, Mr C. B. Lockwoop, was in the chair, and nineteen
members and one visitor were present.

/

The minutes of the last meeting were read and confirmed.

The following officers were then elected for the ensuing year :—
President—C. B. Lockwood. Vive-Presidents—Arthur Thomson,
M.B.; A. M. Paterson, M.D.; J. Yule Mackay, M.D. Treasurer—
G. B. Howes, LL.D., F.R.S. Secretaries—Peter Thompson, M.D.
(England); R. J. A. Berry, M.D., F.R.S.E: (Scotland); N. H.
Aleock, B.A., M.D. (Ireland). Cowncil—C. Addison, M.D.; A.
Birmingham, M.D.; J. Black, M.i3}.; T. H. Bryce, M.D., F.R.S.E;
D. J. Cunningham, M.D., F.R.S.; A. F. Dixon, M.B. ; E. Faweett,
M.B.; R. J. Gladstone, M.D.; T. Wardrop Griffith, M.D.; A.
Keith, M.D.; R. C. Lucas, M.S.; J. Musgrove, M.D.; F. G.
Parsons; C. J. Patten, M.D.; W. G. Ridewood, D.Sc.; Arthur
Robinson, M.D.; Barclay Smith, M.D.; J. Symington, M.D.; G. D.
Thane; B. ©. A. Windle, M.D., ERS.

The Treasurer’s Report, showing a balance in hand of £85, 13s. 6d.,
Was received and adopted. In presenting the report, the Hon.
Treasurer remarked that one satisfactory feature of the balance-sheet
was the fact that the income for the year had slightly exceeded the
expenditure, which had not always been the case in the past. Refer-
ring to the recovery of arrears, he pointed out that the amount thus
received had brought the balance in hand up to a sum which throughout
his twelve years of service had been but once before approached. He
was proud of it, as it marked the recovery of arrears of six to eight
years’ standing, almost despaired of. It was the more welcome, now

a

li PROCEEDINGS OF THE

that the Society would probably embark on a new bibliographic
venture, and would during the year have to meet the major part of
the cost of production of the MS. index to vols. 31-40 of the
Journal of Anatomy and Physiology, now well advanced.

The following candidates were elected members of the Society :—
S. C. Paun, F.R.C.S., Lecturer on Anatomy, Ceylon Medical College,
Colombo, proposed by Arthur Robinson, Peter Thompson, E. J.
Jenkins. Joun Cameron, M.B., Ch.B., M.R.C.S., Bute Anatomy
Department, University of St Andrews, Fife, N.B., proposed by
James Musgrove, G. D. Thane, Peter Thompson.

A Report was next read by the Honorary Secretary for England
which had been received from Prof, G. D. THanz, the Chairman of
the Committee appointed to deal with the supply of slips of items
relating to anatomy, to the International Catalogue of Scientific
Literature. The slips for 1901 are now completed, and to enable the
work to be carried on it was decided that the sum of £10 be placed
at the disposal of the Committee.

Specimens and Papers Beas

(1) Dr R, N. Sauaman showed a specimen of Volvulus affecting that
tract of the small bowel developed from the anterior segment of the
primitive intestinal loop. The specimen was from a child which died
three days after birth. The mesentery of the small bowel was only
attached round the superior mesenteric artery. The coils of the
intestine had become twisted round a pedicle represented by the
vasa intestini tenuis. This had led to occlusion of the vessels and
gangrene of the bowel. The part of the bowel developed from the
posterior segment of the loop—that part distal to Meckel’s diverticulum
—was normal in form and unaffected.

(2) Mr Keiru showed a specimen of Volvulus formed by the cecum,
ascending colon, and terminal purt. of the ileum. The bowel had
become twisted round a pedicle represented by the ileo-colic artery.
The condition was due to the absence of a meso-cecum aud meso-
ascending colon.

(3) The Anatomy of the Valvular Mechanism round the Venous Orifices
of the Right and Left Auricles, with some Observations on the
Morphology of the Heart. By Arraur Kerra, M.D.

Introductory.—lt is evident that the orifices of the great systemic
veins which terminate in the right auricle, as well as those of the
pulmonary veins in the left auricle, must be closed at the com-
mencement of each auricular contraction, otherwise the force of the

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. ili

contracting auricles would be spent as much in returning the blood
to the veins as in passing it on to the ventricles.

Some years ago my colleague Dr Leonard Hill, F.R.S., told me
that he was convinced, from observations he made while carrying out
experiments on the circulation, of the presence of a valvular mechanism
at the terminations of the vene cave in the right auricle. At the
time I could not suggest the anatomical basis of such a mechanism.

Recently, while investigating the anatomy of the diaphragm and
verifying the action of its several parts in the living by the aid of
Réntgen rays, I was struck by the mass of the right crus and its
insertion—indirectly, it is true—to the termination of the inferior
vena cava and pericardium (see fig. 6), It was evident that the
contraction of the right crus of the diaphragm—constituting one
fifth of the total weight of its muscle—was expended on the heart.
It was easy to see that it could exert, to a certain extent at least,
a constricting influence on the venous orifices of the right auricle ;
but further investigation showed that while the presence of the right
erus of the diaphragm was necessary for the closure of the venous
orifices of both right and left auricles, yet the mechanism whereby
these orifices were closed lay in the walls of the auricular chambers.

Statement of Results.—

1. That at the commencement of each auricular systole the
systemic and pulmonary venous orifices are closed, and the parts of
the auricles derived from sinus venosus in the right and left auricles
are shut securely off from the true auricles by certain bands of
muscle.

2. That in valvular diseases of the heart, which lead to back pres-
sure of the blood in the auricular chambers, the muscular valvular
mechanism which closes the venous orifices at first hypertrophies and
remains competent; as long as this is the case no serious symptoms
are manifested. When the disease has proceeded to an extent which
leads to a destruction and atrophy of the valvular mechanism, then
all the worst symptoms of heart disease appear. Further, as that
part of the mechanism which surrounds the termination of the
inferior vena cava is the most delicate, it is the first to break down.
That round the superior vena cava is so strong that I doubt if it
ever becomes incompetent. The mechanism of the superior pulmonary
veins of the right and left lungs is stronger than that of the two
inferior veins,

3. The arrangement of the musculature of each auricular chamber

is such, that when the vestibular part—that part of the auricle

derived from the sinus venosus—is shut off from auricle proper, the
auricular appendix is pulled until it lies over the base of its cor-
responding ventricle, with its mouth directed against the corresponding
auriculo-ventricular orifice. The structure of the appendix gives the
contraction of its muscle a hydraulic effect; by its contraction the
ventricle receives the final complement of its load.

4. All the elements of the reptilian heart can be identified in the
avian and mammalian heart ; and although the manner in which these

iv PROCEEDINGS OF THE

elements are combined differs somewhat in the reptilian and
mammalian heart, yet the function of each element remains constant.
The heart may be defined as the most conservative organ of the
body ; it has always served the purpose of a pump; the only
alteration it undergoes from one end of the vertebrate kingdom to

ouf- 1) Wl Ewst! valve

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Fig. 1.—Wax cast of the right auricle of a child’s heart (1 year old) viewed from
the right lateral aspect. The cast rep tren the shape of the right auricle
when contraction has just commenced.

the other is due to an alteration in the manner ‘by which the blood
is arterialised, wee .

5. The functional value of the various elements described by His
and Born as taking part in the separation of the right and left

oO,
ia

a eee oh ee

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. Vv

-chambers of the heart can he recognised by a study of the evolution
of the vertebrate heart, and the observation of both men, apparently
discrepant, reconciled. That while His and Born are undoubtedly

- correct in their observation of fact, they probably err in the interpre-

tations of these facts. Both men regard the various septa of the heart
as ingrowths from the wall of the primitive cardiac tube.’ While to
a certain extent this may be true, yet it is impossible to account for
the form and structure of the vertebrate heart, and the many mal-
formations to which it is subject in man, except on the supposition
‘that the auricles proper and the ventricles are outgrowths from the
‘primary cardiac tube—in fact, these chambers appear on the cardiac
‘tubes as soap-bubbles are blown from the bow! of a pipe.

Methods employed.—

1. Of the various methods which have proved advantageous in this
investigation, the most profitable has been the study of the heart in
situ, and especially by exposing it from behind by removing the lower
dorsal and upper lumbar regions of the spinal column.

2. By the use of “heat-contraction”—by availing myself of the

well known fact that the application of a substance at the boiling-

point of water to a dead muscle causes it to undergo a contraction
which is physically similar to a normal contraction in life. By
applying a steam-jet to a muscular fasciculus, an approximation to its
normal contraction is obtained. By pumping water near its boiling

_. point into a heart in situ the various chambers, but especially the

thin-walled auricles, are thrown into a state of contraction. By
injecting molten paraffin wax at a temperature of boiling water, casts
-of the auricular chambers in various degrees of contraction may be
obtained—a method which I find has been already employed by
Hasse.

3. By studying the action of the various muscular fasciculi of the
auricles when these fasciculi are traced on casts of the auricular
chambers. This is a method of investigation of the greatest advantage
‘in the study of all hollow muscular viscera. The cast represents the
load of the viscus; when the various muscular fasciculi are traced on
‘the cast, then one can see the part played by each fasciculus in

_ discharging the load of its viscus.

4. By verifying ali the conclusions arrived at from a study of the
normal human heart, (a) on the human heart in pathological

conditions, (b) on the malformed human heart, of which there is a

wich collection in the London Hospital Museum, (c) on the splendid
“comparative series” of hearts in the Museum of the Royal College
of Surgeons of England, (7) on to the models of the development

-of the human heart by His and Born.

The venous orifices of the right auricle.—It is necessary to give a
short description of the three venous orifices of the right auricle—
superior caval, inferior caval, and coronary, for the accounts given in
*text-books are not accurate enough to serve my present purpose.
References to figures 1, 2 and 3 will make my description easier. to
understand.

vi PROCEEDINGS OF THE

(a) Superior caval orifice —The superior caval orifice is elliptical in
shape, with an anterior, right or Hustachian, and a posterior, left or
septal margin. The margins meet at a left or mesial and at a right
or lateral fornix, the latter being situated at a much lower level—as.
regards man in the upright position—than the mesial fornix (see fig 3).
The position and relationship of the mesial fornix, which is rounded in
shape, requires careful definition. It will be observed (see fig. 2)
to be situated at the angle where the anterior or aortic wall of the
left auricle, and the mesial or aortic wall of the right auricle, join
with the interauricular septum. To this junctional angle, which is
a constant feature of mammalian and avian hearts, it is necessary to-
refer again and again. It is always situated over the posterior or

en

omnia. Gm. tiniske .

Fic. 2.—Horizontal section of the heart to show the aortic angle of the auricles-
and the relationship of the superior vena cava to the two auricles.

dorsal cusp of the aortic semilunar valve. The angle in which the
aortic. walls of the two auricles fuse with the interauricular septum
may be named the aortic angle of the auricles (fig. 2).

The superior caval orifice is closed by the anterior or Eustachian
margin being brought firmly against the septal margin. ,

(b) The inferior caval orifice.—The inferior caval orifice is also-
elliptical in shape, with an anterior, right or Eustachian, and a posterior,
left or septal margin. The two margins terminate at a left or mesial
fornix, and a right or lateral fornix, which is situated at a much higher
level—in the upright posture—than the mesial fornix (fig. 1). The
mesial fornix is situated at the inner or mesial angle of the base of

the septum ovale, the outer fornix at the lateral angle of the base of
the septum (fig. 4).

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. Vii

The inferior caval orifice is closed by the anterior or Eustachian
margin being brought in contact with the septal margin.

The suleus terminalis.—It will be seen (see fig. 3) that the lateral
fornices of the superior and inferior caval orifices approach each other
on the lateral wall of the auricle, being a little less than one inch
apart in the normal human adult heart. The lateral fornices are
connected by the sulcus terminalis (His), an indifferently marked
fibrous septum which marks the line at which that part of the sinus

Fic. 3.—Heart of an adult viewed from the right lateral aspect, to show the
manner in which the vene cave terminate in the right auricle. The crosses
mark the points which are fixed during the contraction of the heart.

venosus which connected the superior and inferior ven cave in the
foetus, sunk within and was overgrown by the proper auricular
musculature. ‘The distance between the lateral fornices of the caval
orifices is scarcely altered in contraction of the auricle.

The relationship of the septum ovale and annulus ovalis to the
inferior caval orifice.—The base of the septum ovale is continuous
with the septal margin of the inferior caval orifice, and hangs over
that opening like a partially opened lid (see figs. 8 and 11), The
lower or right surface looks into the lumen of the inferior vena cava,

Vili PROCEEDINGS OF THE

and towards the crest. of the right ilium. While the base of the
septum ovale is fixed or hinged to the septal margin of the inferior
caval orifice, its convex margin is overlaid by the annulus ovalis.
The annulus is made up of two distinct parts, differing in origin and
in function. The inferior limb of the annulus, referred to after-
wards as the inferior limbic band, starts from the mesial fornix of the
inferior caval orifice, and ends in the aortic auricular angle and in the
central fibro-cartilage (see figs. 4, 7, 9, 10, 11). The superior limb of
the annulus, the superior limbic band, begins at the lateral fornix of

Sup.norf

eho: uk.
ih — :

ity

Fic. 4.—The right auricle of the heart of a child 4 years old is thrown open.

The Eustachian margin of the inferior vena cava is thrown outwards, and

a musculi pectinati divided just above their union with the left annular
and.

the caval orifice ‘and terminates in the aortic auricular angle (see figs.
2, 4,11). The part played by these two bands in closing the inferior
caval orifice will be explained presently; it is necessary to describe
their situation to make the description intelligible. Further, the
septum ovale enters into the formation of the anterior or ventral wall
of the left auricle.

(c) Coronary orifice in the right auricle.—This orifice, situated at
the base of the interauricular septum, is also. elliptical in shape, with
an anterior, right or Hustachian margin, a posterior, left or septal
margin, these margins :terminating at a mesial and a lateral fornix

—— a

ee eae

Se se ee

- ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. ix

(fig. 4), It also is closed by the approximation of the Eustachian to
the septal margin.

These three venous orifices open in the vestibule of the right
auricle—that part of the auricle derived from the right sinus
venosus. It will be more strictly defined at a later stage of. this

paper.

Fie. 5.—A dissection of the heart from behind to show the arrangement of the
muscular fibres of the left auricle and the relationship of the auricle to the
inferior vena cava. To be compared with fig. 6.

The position and shape of the venous orifices of the left auricle,—
A reference to tig. 5 will make the brief description given’ here
intelligible. The left auricle, like the right auricle, is made up of
three parts, each of which serves a separate purpose in the auricular
systole. The first of these parts is the vestibule, the part derived

x "PROCEEDINGS OF THE

from the left sinus venosus, and into which the pulmonary veins pour
their blood. It is completely separated from the rest of the auricular
chamber in systole. The second part is the auricular appendix.
The third part is the atrium into which the appendix and vestibule
open (figs. 5, 11). The atrium descends into an angular recess
situated between the septum ovale, the posterior or left margin of
the left auricular ventricular orifice, and the vestibule (see fig. 11).

The vestibular part, into which the pulmonary veins open, is nearly
square in outline, as seen on the dorsal aspect of the heart (fig. 5).
Its posterior or dorsal wall is nearly stationary during the contraction
of the auricle; the interauricular septum and aortic wall of the left
auricle become then applied to it (fig. 11). In the systolic phase,
the posterior wall presents a sharp upper margin, passing from the
right superior pulmonary vein to the left superior vein (fig. 5).

In each of the four angles of the vestibule of the left auricle is
the opening of a pulmonary vein (figs. 5, 6). The superior angles
are more elongated than the inferior. Until the pulmonary veins
perforate the pericardium, they are destitute of striated muscle fibres.
The pulmonary venous orifices are elliptical in shape, with posterior
or dorsal and anterior or ventral margins. The musculature round
their terminations does not possess a sphincter-like action, but. closes
the pulmonary orifice by the approximation of their two margins.

The fixed points at auricular base of the heart.-- Before proceeding
to describe the manner in which the venous orifices of the auricles are
shut, it is necessary to direct attention to the manner in which
certain parts of the auricular chambers are fixed in position. These
fixed points are the bases from which the muscle bands act in closing
the venous orifices. If the muscular bands are detached from their
points of fixation, then they can no longer exert such an action.
Hence the necessity for studying the heart in situ,

(a) Fixed points of the venous orifices of the right auricle.—There
are two such points for the right auricle (see figs. 3, 6). The lateral
fornix of the inferior caval oritice is fixed firmly to the central tendon
of the diaphragm and indirectly to the right crus. The lateral fornix
and the right or lateral margin of the terminal part of the superior
vena cava are fixed to all those structures of the middle mediastinum
which form the root of the lung (fig. 3). By the fascial tissue round
the superior vena cava, the lateral fornix of the superior caval. orifice
is fixed indirectly to the upper aperture of the thorax. The dorsal
part of the pericardial sac passes from the lower to the upper of
those fixed points, and maintains them in relatively the same
relationships in all stages of a respiratory cycle (see figs. 5, 6, 7 and
16). It should be noted that the mesial fornices of the caval
orifices, unlike the lateral, are free, and it is these mesial parts of the
caval orifices that undergo the greatest amount of movement and
contraction during the systole of the auricle. The points of fixation
are confined to the vestibule of the right auricle.

The fixed points of the left auricle.—The sinus obliquus of the peri-
cardium passes up behind and covers the whole of the posterior wall

a

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. Xi

of the vestibule of the left auricle (figs. 5 and 6). Its upper
boundary corresponds to the superior margin of the vestibule, which
lies between the right to the left superior pulmonary vein (fig. 6). Its
left boundary is formed at the left margin of the vestibule of the
auricle, and passes from the superior to the inferior left pulmonary

WON) La
\ \ HA ify

Fic. 6.—A dissection of the heart from behind to show its points of attachment.
Two windows have been made in the pericardium to show the right and left
auricles. The diagram shows how the right crus of the diaphragm acts on
the base of the heart and roots of the lungs.

vein. Its right boundary corresponds to the right margin of the
vestibule, which passes from the superior to the inferior right pul-
monary vein. These three margins of the vestidu/e of the left aruricle
are fixed. The three lines of attachment may be described as left
marginal, superior marginal, and right marginal. By the right

xii PROCEEDINGS OF THE

marginal attachment the vestibule is fixed to the root of the right
lung, and through the lung to the whole right parietal wall of the
chest. By the left marginal attachment, to the root of the left lung
and left wall of the thorax. By the superior marginal attachment it
is fixed to the pulmonary arteries and the bronchi. If these three
attachments are destroyed, then the musculature which closes the
vestibule of the left auricle can no longer act.

Further, it is to be noted that the right marginal attachment is
continuous above with that of the right margin of the superior vena
cava, below with that of the inferior vena cava (fig. 6).

The action of the right crus of the diaphragm on the pericardium
and heart.—The fixed points I have described belong to two quite
distinct classes. They may be distinguished as inferior or diaphrag-
matic and superior or pulmonary. All three attachments of the left
auricle belong to the latter set, and so does that of the superior caval
orifice. The inferior caval orifice is the only one fixed to the
diaphragm, and this attachment is found in all mammals. The more
extensive attachment of the pericardium to the diaphragm found in
animals adapted to an upright method of progression, such as man
and the anthropoids, is a result of their adaptation to that posture.
The primitive and essential attachment to the diaphragm is that at
the lateral fornix and lateral margin of the inferior venacava. At the
diaphragmatic attachment of the heart terminates the massive fibres

of the right crus (fig. 6). The superior attachments are bound to the
inferior by the posterior or dorsal wall of the strong fibrous pericar-
dium and by the right marginal attachment of the left vestibule (fig. 6).

A reference to figs. 7 and 16 will show that the posterior wall of
the fibrous pericardium is essentially a tendon by which the right
crus of the diaphragm acts on, not only the inferior caval orifice, but
also on the upper auricular attachments and roots of the lungs.

This conclusion was arrived at froma consideration of the ana-
tomical arrangements of the parts. A prolonged examination of the
action of the diaphragm in life, by the aid of Réntgen rays, showed
that the conclusion was right. In each inspiration the base of the
heart, the roots of the lungs and their constituent parts are moved
downwards and forwards, so that the base of the heart is separated
by a greater space from the spinal column. When one thinks of it,
the matter becomes really one of common-sense, for it is quite
evident that, to allow expansion of the lungs to take place on
inspiration, their roots must move downwards and forwards to allow
such an expansion to take place. The lungs can expand only to a
slight degree in an upward or backward direction, owing to the
immobility of these parts of the chest wall.

The ‘respiratory pump’ action of the right erus.—The right crus
not only maintains the fixed points of the auricles in their proper
relative positions during the various respiratory movements of the
heart, but it is the most essential part of that mechanism which has
been described by Dr Leonard Hill as the ‘respiratory pump.

A reference to fig. 7 will assist me in making clear one of the most

Oe ee Oe ee ee ee ee

—— Oa ee

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. Xxiil

ingenious adaptations in the organisation of the body, and which, as far
as I know, has not attracted much attention. The inferior cava (fig.
7) lies between the liver in front and the right crus behind. At the
commencement of an inspiration, as a breath is being taken, the right
crus contracts and forces the blood from the inferior cava to the right
auricle, an increased supply of blood being thus sent to the right side
of the heart at the commencement of each inspiration. At the same
time the crus exerts its force on the left auricle through the dorsal

Fic. 7.—Vertical section of the ven cave and right auricle viewed from the
right lateral aspect. It shows the termination of the right crus in the
inferior vena cava and base of the heart. Also the muscular bands round
the fossa ovalis.

wall of the pericardium. Traction on the pericardium from below
has two effects: it tends to empty the left auricle, and at the same
time, by the traction it exerts on the termination of the pulmonary
veins, tends to close them. Thus, during the phase of inspiration,
the action of the crus assists increasing the supply of venous blood to
the lungs and in decreasing the outflow to the left auricle. During
expiration, on the other hand, its effect is quite the reverse.

The structures which close the venous orifices of the right auricle.—
It is now possible for me, with some hope of making my description
intelligible, to give an account of how the venous orifices and the

xiv PROCEEDINGS OF THE

vestibule (that part of the right auricle derived from the sinus venosus)
come to be shut off from the auricular afriwm, or proper auricle, at
the commencement of each auricular systole. Four muscular bands

a

CALE
ct
: |

4| taenia
| temumalss

af, Sj

se i fea bic band NF j LB band
Cot. otsfece VE SONG inf.

Her, |p CO).
WE ¥i 1¢. :
Wa 6 if é

Fic. 8.—Cast of a child’s right auricle viewed on its dorsal aspect. The position
of the aortic angle and certain muscular bands is shown (from the preparation

shown in fig. 1).

bring about this effect—they are present in all mammalian hearts.

They are—
1, The tenia terminalis (figs. 1 and 4).
2, The inferior limbic band (inferior limb of the annulus ovalis)

(fig. 9).

oy | 4 a

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. XV

_3. The superior limbic band (superior limb of the annulus ovalis)

mi « (fig. 9). :

4. The septal band of the right auricle—auricular fibres in the
septal wall of the superior caval orifice.

1. The tenia terminalis.—This is by far the chief factor in
closing the right venous orifices. It is shown in fig. 4, and its
position is indicated on the casts of the right auricle shown in figs.
land 8. It commences at the mesial fornix of the superior caval
orifice, fusing with the musculature of the aortic angle (fig. 2).
Passing along the Hustachian or anterior margin of the superior
caval orifice and the anterior margin of the sulcus terminalis, it
terminates below, near the lateral fornix of the inferior caval orifice
(fig. 9), by fasciculi which end in the Eustachian fold or valve, and
also in other fasciculi which form the lower of the series of the musculi
pectinati. By these it is attached to the middle point of the dorsal
margin of the right auriculo-ventricular orifice. The musculi pectinati
are given off from the left margin of the tenia terminalis (fig. 9),
but the musculi pectinati have only an indirect action, which will
be alluded to presently, in closing the inferior caval orifice. It is
essential to note, in order that the action of the right tenia terminalis
may be appreciated, that there is a corresponding band in the left
auricle—the tenia terminalis sinistra. The left band also starts from °
the aortic angle and sweeps round the vestibule of the left auricle
(fig. 13). That the aortic angle may be identified on the inner aspect
of the right auricle, it may be mentioned that the convexity of the
annulus ovalis is embedded in it. In the auricular systole both
contract together, the one tenia acting as an opponent to the other.
When the right tenia terminalis contracts, it descends within

_ the right auricle like the blade of a falchion (fig. 9). The anterior

or Eustachian margin of the superior caval orifice is brought down-
wards and inwards until it approaches the aortic wall of the right
auricle, just in front of the aortic auricular angle (figs. 2 and 9).
The lateral fornix of the inferior caval orifice is the only point at
which the tznia terminalis is absolutely fixed (fig. 6). Hence, when
this band contracts, the mesial or left fornix of the superior caval
orifice is drawn towards the lateral fornix of the inferior caval
orifice (figs. 1, 8, 9).

2. The inferior limlic band.—This band is really, in nature, a
musculus papillaris. It might be described as the fensor valvule
Hustachii, but such a term does not describe its action fully. It is
attached to the Eustachian valve and inner or mesial fornix of the
inferior caval orifice (figs. 4, 7, 9). From that origin it passes to
its insertion on the central fibro-cartilage of the heart (see figs. 7, 9
and 10). The band acts in two ways: it lifts up and renders tense
the Eustachian valve along the anterior or Eustachian margin of
the inferior caval orifice, and at the same time brings the bases of
the ventricular orifices towards inferior caval orifice—thus assisting
to close the vestibule of the right auricle (figs. 1 and 9).

It will be observed that the mesial extremity of the Eustachian

XVi PROCEEDINGS OF THE

valve is attached to the inferior limbic band, its lateral extremity to
the tania terminalis (fig. 4). These two bands practically encircle
the auricle and separate its vestibule from its atrium (figs. 1, 8).
It must be remembered, however, although the Eustachian valve
is made tense and stretched so as to bring it somewhat towards the
septal margin of the inferior caval orifice, that it is the aortic auricular
angle (fig. 2) and the central fibro-cartilage of the heart (fig. 10)
that are the movable points, and these are brought towards the
inferior caval orifice (fig. 9).

AN /

bug gluon ZA
Ve gs

Fic. 9.—The right auricle of a child’s heart, which was thrown into a partial
contraction by the injection of hot wax, opened and view from the front.
_The anterior wall is thrown to the right; the right tenia terminalis is
pulled upwards and to the right to show the parts which it covered. It
was in contact with the interior limbie band.

The Eustachian valve-——This valve forms the anterior, right or
Eustachian margin of the inferior caval orifice (fig. 7). It is never
absent in the normal human heart. It is only absent when destroyed
by the effects of disease. The denial of its presence is the result of a
failure to distinguish between this valve and the right venous valve
of the sinus venosus. The Eustachian valve, it is true, is part of the
right valve of the sinus venosus, but it is derived from only the basal

es!
oT

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. XVii

part of that segment of the right venous valve which forms the
anterior margin of the inferior caval orifice. The free, non-muscular
part of this segment of the right venous valve is fretted and forms a
thin network, and disappears at birth or soon after. But the basal part
which forms the Eustachian valve is always present. The mem-
branous part of the right venous valve which skirts the anterior or
Eustachian margin of the superior caval orifice disappears, but its
position can be distinguished (fig. 4).

The sub-Eustachian sinus.—This is the Valsalval sinus of the inferior
caval orifice, and it is not only present in all mammalian hearts, but
can also be seen in the reptilian auricle (figs. 1, 3, 4, 5, 7, 8). It is
formed by that part of the atrium of the right auricle which lies
between the Eustachian valve and left margin of the orifice of the

Fic. 10.—Preparation to show the relationship of the central fibro-cartilage to
the posterior cusp of the aorta, to the auriculo-ventricular orifices, and to
the opening of the coronary sinus.

right ventricle. There the auricular wall is extremely thin and
only slightly muscular. It is in reality an interval between the
lowest of the musculi pectinati and the muscular fibres of the tania
terminalis that end on the lateral fornix and Eustachian margin
of the inferior caval orifice (figs. 1, 4, 8). When the muscult
pectinati, by which the wall of the atrium is formed, begin to
contract, the sub-Eustachian sinus is unduly distended by the
tension thus raised in the atrium. The Eustachian or free part of
the anterior margin of the inferior caval orifice (fig. 7) is pressed
backwards by the distending sinus until it is firmly applied to the
septal wall (figs. 9, 15).

3. The superior limbic band.—The action of the superior limbic

b

XViil PROCEEDINGS OF THE

band (superior limb of the annulus ovalis) in closing the vestibule
and venous orifices of the right auricle, can be seen by referring
to figs. 9 and 11. It takes its fixed origin from the lateral fornix
of the inferior caval orifice, from the sulcus terminalis just above
that fornix, and by a series of fibres (see fig. 5) from the left or
septal margin of that orifice. From those points of origin the band
passes on the right aspect of the interauricular septum to terminate in
the aortic auricular angle (fig. 2), and some of its fibres join those of
the inferior limbic band.

At the commencement of an auricular systole, this band draws
back the aortic angle of the auricles, and consequently the base of
the right ventricle towards the lateral fornix of the inferior caval
orifice (fig. 15). It thus assists in emptying the vestibule of the
right auricle, and coming against the tenia terminalis, shuts the
vestibule off from the atrium (fig. 9).

4. The auricular fibres at the septal margin of the superior caval
orifices (figs. 7 and 11).——This is the fourth and last of the bands of
muscular fibres which have to be considered in connection with the
closure of the caval orifices of the right auricle (figs. 7 and 8). The
fibres of this flat band rise from the fibrous tissue of the saleus
terminalis (fig. 11), and proceed backwards in the auricular septum
and septal wall of the superior caval orifice to terminate in (a) the
aortic angle (figs. 2 and 11), (6) the tenia terminalis sinistra
(fig. 11). Their main function is to draw backwards the aortic angle
and ventricular bases, and thus empty the vestibule of the right auricle.
At the same time, this bundle becomes approximated to the tenia
terminalis, thus occluding the superior caval orifice (figs, 2, 15).

Tubercle of Lower.—It is this muscular band that gives rise to the
tubercle of Lower. The tubercle is well marked in all pronograde
mammals. In these the superior and inferior caval enter the vestibule
of the right auricle at an angle to each other, which is about 100° in
extent. In orthograde mammals, the anthropoids and man, the venz
cave are more nearly in a line, and open at an angle to each other of
about 140°. Thus in pronograde mammals there is a distinct angle at
the junction of the cave in the septal wall, below and to the right of
the superior caval orifice ; in that angle is the septal band of muscle
just described. To apply the term tubercle to a band of muscle is a
misuse of terms, but it would be extremely convenient to retain the_
term as the angle of Lower, so that one could indicate the degree of
inclination of the superior cava to the inferior cava as these vessels
entered the vestibule of the right auricle.

Using the term as above defined, it may be said that the angle of
Lower in the human foetus at and before birth is of only slightly
greater extent than the corresponding one in pronograde mammals.

Loop-shaped fibres at the termination of the superior vena cava
(fig. 13).—The terminal half-inch of. the superior vena cava is
surrounded by loops of muscular fibres. The convexities of the loops
are thrown round the mesial or left margin of the superior. vena and
terminate at the right or lateral margin near the lateral fornix of the

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xix

vein (figs. 8 and 11). They assist in constricting the terminal part
of the vein and assist the tenia terminalis. These fibres I regard as
the only representative of the musculature of the sinus venosus now
remaining in the mammalian heart. All the other bands that help to
close the orifices are derived from the auricle. It is probable that
the contraction of the vestibular systole is initiated in the loop fibres
of the vena cava.

Fic. 11.—The foramen ovale—the oval space between the limbs of the annulus
ovalis—exposed from behind by removing (1) the posterior wall of the left
vestibule, fo) the fibres of the interauricular septum belonging to the left
vestibule. Owing to an attempt to leave an outline of the right pulmonary
veins, the arrangement of the septal fibres appears somewhat involved.

The coronary orifice—The closure of the coronary orifice can be
briefly described. The anterior or Eustachian margin is formed
by a fold which is derived from the lower or ventricular extremity
of the right venous valve (see figs. 14, 19, 20). The septal margin
is formed by the mesial or ventricular extremity of the inferior
limbic band (fig. 4). This band is developed in the base of the mesial

XX PROCEEDINGS OF THE

(ventricular) extremity of the left venous valve and in the fold of the
sinus venosus which separates the right and left horns of that cavity
(see fig. 14).

The contraction of the inferior limbic band brings the septal margin
of the orifice against the valvular fold on the Eustachian margin.

The valvular mechanism of this orifice frequently breaks down in
cases of venous back pressure. It is the next to fail after that of the
inferior cava, and I suspect that many of the unexplained symptoms
of heart disease are due to the hypertrophied right auricle pumping its

Fic. 12,—Left tenia terminalis and anterior wall of the vestibule of the left
auricle. They are exposed by the removal of the posterior wall of the
vestibule. The crosses mark the line along the base of the septum with
which the left tenia terminalis comes into contact in systole of the auricle.

blood into the coronary sinus and veins of the walls of its own heart.
The valves at the terminations of the cardiac veins in the coronary
sinus are not strong enough to resist such a persistent force as that
of the hypertrophied right auricle. ;
It will be seen that when the tenia terminalis sinks within the
auricle, and when the superior limbic band contracts and pulls back
wards the aortic angle of the auricle, that the convexity of the
superior limbic band tits accurately within the concave margin of the
tenia terminalis (fig. 9). The more these bands contract the firmer
they are locked in each other’s embrace, so that it is impossible that there

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. XXi

could be a regurgitation of the blood in the atrium into the vestibule
_ orsuperior vene cave. The firm application of the Eustachian margin
of the inferior caval orifice to the septal wall forms a competent valvular

ism, and as long as this margin remains intact, there can be no
regurgitation of blood to the inferior cava.

Remnants of the left venous valve of the sinus venosus and of its
musculature.—In order that the septal margin of the inferior caval
orifice may be straightened and become a firm basis against which
the Eustachian margin may come in firm and uniform contact, a band
of muscle is present. This passes along the septal margin of the
orifice, commencing in the inferior limbic band (fig. 7), and ends in
the superior limbic band (fig. 11). It is a remnant of the musculature
of the left venous valve. It skirts the septal margins of both the
superior and inferior caval orifices and assists in bringing their margins
together (fig. 11). ‘

It is usually said that there is no trace of the left valve of the
sinus venosus to be seen in the fully formed human heart. On the
contrary, two very distinct remnants can always be seen on the septal
margins of the two caval orifices. That at the inferior caval orifice
forms fibrous reticulations along the base of the septum ovale (fig. 4).
On the septal wall of the superior caval orifice it forms the valvular
fold of the endocardium which covers and protects the mouth of the
septal vein of the auricles (fig. 4).

The occlusion uf the vestibule and venous orifices of the left auricle.—
The manner in which the vestibule and venous orifices of the left
auricle are shut at the commencement of an auricular systole will
be best understood by referring to figs. 5, 12 and 13. Three parts
of the musculature of the left auricle are employed to attain this
end. They are—

1, The teenia terminalis sinistra.
2. The left septal expansion or band.
3. The semicircular bands surrounding the venous orifices.

1. The tenia terminalis sinistra.—Just as in the case of the
right auricle, but to a more marked extent in the case of the left,
this strong muscular band, when it contracts, separates the vestibule
of the left auricle from the cavities of the atrium and appendix. Not
only is it similar to the right tenia in function, and almost in
attachments, but it is also identical in the manner in which it is
_ developed (see p. xxxiii).

The tenia forms an almost complete circle, as complete as the
external semilunar cartilage of the knee-joint, which it somewhat
Tesembles (fig. 12). Its anterior or ventral extremity starts in the aortic
angle of the auricle ; there it fuses with the corresponding teenia of the
right side and with the septal band of the superior caval orifice (see
figs. 2,11 and 13). The posterior or dorsal extremity has a rather
extensive attachment (figs. 11 and 12). Some of its fibres reach the

XXii PROCEEDINGS OF THE

central fibro-cartilage of the heart, others end in the septal margin
of the inferior vena cava and left margin of the left auriculo-ventricu-
lar orifice (figs. 11 and 12.)

In fig. 11 the left auricle is represented in a state of partial con-
traction. The tenia terminalis has become drawn within the cavity
of the left auricle. Its free crescentic edge is directed towards and
ultimately comes into close contact with the base or ventricular
margin of the septum ovale. It is similar in origin, nature and
action to the opponent band of the right side. It shuts off the
vestibule of the left auricle from the atrium.

The left septal expansion (figs. 5 and 11).—This muscular expansion
corresponds in position, action and origin to the superior limbie band

Fic. 13.—The aortic angle and aortic walls of the auricles exposed by removing
the aorta, left ventricle, and the greater part of the right. The origin of
the left tenia terminalis is shown. The appendix of the left auricle is also
removed. The thin triangular area on each side of the septum is indicated.

and septal fibres of the superior caval orifice of the right auricle (see
figs. 11, 17, 7). The fibres arise chiefly from the superior marginal
attachment of the left auricle, but also from the right and left
marginal attachments of the left vestibule (fig. 5). These points
are fixed. The fibres enter the septum of the heart and terminate
in the right margin of the left auriculo-ventricular orifice—in the dorsal
half of that margin (see fig. 11), Its insertion will be seen to lie
within the concavity of the crescentic margin of the tenia terminalis
(fig. 12). When contracted they lock upon each other.

It can now be seen how the teenia semicircularis and septal band

ANATOMICAL SOCIET¥ OF GREAT BRITAIN AND IRELAND, xxiii

shut the vestibule of the left auricle completely off from its atrium.
The vestibule has only two walls, a posterior or dorsal, formed
chiefly by the left septal expansion (fig. 5), and a ventral or anterior
(fig. 12), formed (1) by the inter-auricular septum, and (2) by the
left tenia terminalis (fig. 15). The combined action of the left
teenia terminalis and left septal expansion is such that the anterior or
septal wall is pressed firmly against the posterior wall. The com-
munication of the vestibule with the atrium is firmly shut, owing to
the manner in which these two bands are locked, the septal band
expansion hooking round the concavity of the crescentic teenia termin-
alis (fig. 12).

Fic. 14.—Showing how the orifice of the right siuus venosus is subdivided into
three by two infoldings of the sinus wall. In the infolding between the
coronary and inferior caval openings lies the inferior limbic band ; in
that between the caval openings, the right septal fibres and the superior
limbic band. The right and left venous valves are represented.

The looped fibres of the pulmonary orifices.—To make doubly sure,
as it were, that the auricular contraction cannot spread backwards to
the veins of the lungs, looped fibres are placed at the pulmonary
orifices (fig. 5).

Retraction of the ventricles during the auricular systole.—It is a
fact clearly recognised by physiologists that the ventricles are drawn
backwards on the load of blood within the auricles, much in the same
way as a stocking is drawn on the leg. The ventricular base is
drawn towards the fixed points of the heart already described (fig. 6).
In this movement the auricular septal fibres certainly play a part, but
these fibres draw the base of the heart not only backwards but also
towards the inferior caval orifice. The septal fibres only act on a

XXiv PROCEEDINGS OF THE

limited part of the base of the ventricles, the part shown in fig. 12
During the auricular systole each auriculo-ventricular orifice forms a
narrow ellipse; each has a lateral and a mesial margin. Only the
dorsal parts of the mesial margins come into contact (fig. 12). At that
part the margins are fused with the interauricular septum (fig. 15),
It is only this part of the ventricular base that is retracted by the
septal fibres. The remainder of the base of the ventricles is retracted
by the contracting fibres of the auricles proper.

The manner in which the foramen ovale and ductus arteriosus are
closed at birth.—In fig. 16 is shown mesial section of the thorax of a
child at birth. The section which is represented does not show well
the high position of the lungs and heart, the tortuous course of the
cesophagus, or the wavy course of the phrenic nerve at birth. All
are huddled in the upper region of the thorax, waiting the first move-
ment of the diaphragm to bring them into position.

The heart beats under very different circumstances before birth.
The fixed points from which it acts are different. It works under the
same circumstances as does the heart of the bird all through life.
There are no respiratory movements to disturb its action. Most
important of all, the heart is not moved by the right crus of the
diaphragm. It is the action of this muscle at birth which upsets the
principles on which the foetal circulation is conducted.

The action of the superior and inferior limbic bands before birth.—
The fixed points from which these bands act during post-natal life
are the mesial and lateral fornices, but especially the lateral fornix of
the inferior caval orifice. These two points are moved and controlled
by the traction of the right crus of the diaphragm. But in pre-natal
life, the crus being non-operative, these two bands pull the fornices of
the inferior caval orifice within the vestibular chamber to quite as
great an extent as they draw the aortic angle backwards. Indeed the
latter must be by far the more fixed point, for the heart is surrounded
by the solid unyielding lungs. It is extremely probable that the
limbic bands actually pull on the right crus. By this means they
force the blood in the inferior vena cava within the chamber of the
right auricle. The right crus certainly acts as a respiratory pump
after birth, and in the manner indicated it may also serve to feed the
heart before birth.

The manner in which the limbic bands act in pre-natal life prevent
them from completely occluding the vestibule from the atrium of the
right auricle. Hence, when the right auricle contracts, it forces the
blood in two directions— into the right ventricle, and also through a
narrow chink of the foramen ovale into the left auricle. Blood may
also pass through the foramen ovale into the left auricle before the
commencement of the auricular systole. The foramen ovale is an
adaptation to secure an equal pressure in both auricles, and therefore
an equal supply of blood, during auricular systole.

At birth the contraction of the diaphragm—which then descends
downwards and forwards to the extent of about one inch—completely
alters the action of the limbic bands. Their fixed points are now

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND, xxv

defined, and when they and the tenia terminalis contract, the
vestibule of the right auricle, and of course the fossa ovalis, are
completely shut off from the atrium.

Closure of the ductus arteriosus.—By the contraction of the right
crus the ductus arteriosus is also closed. The manner in which this
is accomplished may be seen from fig. 16. The tendon of the crus is
prolonged by theZdorsal wall of the fibrous pericardium to the fixed

Fic. 15.—Diagram to show the occlusion of the left vestibule, the closure of the
ven cave, and retraction of the bases of the ventricles as the auricles are
emptied.

margins of the left auricle (see fig. 15). At the junction of the superior

and left marginal attachments, just where the left superior pulmonary

artery emerges from the root of the lung, lies the ductus arteriosus. To
it is attached the superior left extremity of the dorsal part of the
pericardium (fig. 6). When the right crus contracts at birth, with the
first inspiration, it draws the pulmonary arteries and the fixed margins of
the vestibule of the left auricle with it, but the aorta is fixed otherwise
and scarcely yields. Hence a decided traction is exercised on the

XXV1

PROCEEDINGS OF THE

4

4
}

‘ 4
:

=
Fic, 16.—Vertical coronal section of the thorax of a still-born child, to show the termin

tion of the right crus in the inferior vena cava, septum of auricles, posterior layer of
pericardium, and in sheaths of pulmonary arteries and bronchi.

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xxvii

ductus arteriosus—enough I believe to stop the flow of blood from
the pulmonary artery to the aorta and turn it into the lung, which at
the same moment is expanding.

Thus the contraction of the right crus, while helping to expand
the lung, also closes the foramen ovale and ductus arteriosus.

Fic. 17.—The dorsal aspect of the auricular part of an abnormal (reptilian-like)
human heart. The venous openings are shown on the dorsal aspect of the
opal auricular caval (auricular segment of primitive cardiac tube).

e septal (or intersinuous) areas, the annular (basal) bands of the auricles,
the caudal and cephalic poles, and the primitive arrangement of the musculi
pectinati are also represented.

The morphology of the auricles.—An investigation into the
morphology and development of the auricles shows that the various
structures which close the vestibules of the auricles from the atria
serve identical functions, although they differ in form, in the reptilian,

XXVlii PROCEEDINGS OF THE

avian and mammalian heart. The same elements are present in all
three kinds of hearts; they serve the same function in all; they only
differ in the manner of their combination.

The right and left sinus venosus.—In fig. 17 I have diagrammatised
the dorsal aspect of the auricles of a heart which was obtained from a
human child, but which resembles in every detail the reptilian heart.
The points to be noted are—

1. The right sinus venosus receives the superior cava, inferior cava
and coronary sinus; but, as can be seen from fig. 20, a fold of the sinus
projects within the cavity of the auricle and separates the orifice of
the sinus venosus into two. .

2. The right sinus venosus does not open into the auricle proper,
but into that part of the cardiac tube which I shall indicate as the
auricular segment of the cardiac tube.

3. The left sinus venosus receives the two pulmonary veins, and
also opens into the auricular segment of the primitive cardiac tube.
It is separated from the right sinus by an inflection, similar to that
which we have seen to separate the coronary from the caval openings.
To this inflection— the intersinuous fold—I will have to refer to
again. A reference to comparative anatomy shows that the two
sinuses are originally one.

4. From the dorso-lateral aspect of each side of the primitive
cardiac tube the two auricles have been developed as hollow outgrowths.
On the dorsal aspect of the tube their bases meet; on the ventral
aspect of the tube they do not meet, but leave a narrow tract of the
auricular segment of the cardiac tube.

5. The mouth or base of each auricle is surrounded by a ring
of muscle—the basal ring of muscle. On the dorsal aspect of the
cardiac tube, where the bases of the auricles are in contact, these rings
fuse, elsewhere they are free. From these rings are developed the
valvular venous mechanism of the fully formed heart.

6. Muscular fibres pass elliptically from the lateral segment of each
basal ring, round the auricle, to end in the mesial segment of the ring.
They come to form the musculi pectinati. They are derived from the
basal rings during the growth and expansion of the auricies.

The relationship of the auricular to the ventricular segment of the
primitive cardiac tube-—By an arrest of growth during development,
the terminal part of the auricular tube comes in contact with the
terminal part of the ventricular segment, so that the right margin
of the base of the aorta remains in juxtaposition with the auricle ;
unless this point is grasped, the development of the cardiac septa
cannot be understood (see fig. 18).

It will be seen by referring to fig. 18 that at three points the
primitive cardiac tube remains during development in a condition of
passivity. The first and most important is on the right dorso-lateral
aspect of the primitive cardiac tube where the auricular and
ventricular segments unite. This union forms the right margin of
the right auriculo-ventricular orifice in the reptilian heart (fig. 19) and
also in the abnormal human heart (fig. 20). Its destination is so

eee

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND, Xxix

important that a name must be given it—provisionally it may be
termed the right auriculo-aortic angle (fig. 18). In the fully formed
human heart it becomes fused in the central fibro-cartilage of the

The second point at which the cardiac tube remains stationary is
along a spiral line on the left aspect of the ventricular part of the
cardiac tube. This line forms the upper margin of the interventric-
ular septum. The left ventricle is developed as an evagination from
the ventricular segment to the left side of this line. It grows back-
wards and to the left, giving the ventricular fibres the curious spiral
twist they possess. The right ventricle is produced as an evagination
on the right side of this line, its growth being forwards (ventralwards)
and to the right. The rounded opening between the upper margin

Fic. 18.—A diagram to show the parts of the cardiac tube which remain almost
stationary «uring the development of the heart. The chief stationary point
is on the dorsal aspect of the ventricular part of the tube ; here the auricle
practically joins the aorta. The other is om the ventral aspect of the
auricular part of the tube; here the sinus venosus practically joins the
ventricle. The parts of the tube formed by the sinus venosus and aorta
(truncus arteriosus) are represented in outline: the part by the auricle,
black ; the part by the ventricle, shaded.

of the interventricular septum and auriculo-ventricular angle consti-
tutes the true interventricular orifice, and represents an arrested ring
of the primitive cardiac tube (fig. 18).

The third point of the primitive cardiac tube to remain in abey-
ance is the ventral margin of the auricular segment of the cardiac
tube (fig. 18).

A consideration of these points shows how it is that on the ventral
aspect the sinus venosus comes almost in contact with the ventricles,
and the distal end of the auricular tube with the distal end of the
ventricular.

The morphology and development of the septum ovale,—The septum
ovale is primarily the right valve of the left sinus venosus. That
purpose it serves in the reptilian heart; if serves so in the human

XXX PROCEEDINGS OF THE.

heart (fig. 20); it also serves as such in the human foetal heart until
the time of birth, and after birth it assists to close the vestibule of
the left auricle—a derivative of the left sinus venosus. It acts only
as the right valve; the basal muscular ring of the primitive auricle
brings the left orifice of the sinus against the septum ovale. The
left tenia terminalis is a derivative of this ring and acts in similar
manner in the fully formed heart.

coh ble

N

ml NS =

Fic. 19.—The heart of a python laid open and viewed from the right lateral
aspect. The septum ovale (non-muscular) constitutes the whole of the real
interauricular septum, only the posterior (deeply shaded) part acts as a
pulmonary valve. The right auriculo-ventricular orifice is thrown open ;
it is bounded on the right by the auriculo-aortic valve, the representative of
part of the anterior endocardial cushion ; on the left by another valve, which
represents part of the posterior endocardial cushion.

Development of the septum ovale.-—The septum ovale is developed
by the combination of two elements, but by far the chief one is that
described by His as the spina vestibuli. This is an outgrowth from
the intersinuous fold, or what His has named the area interposita
(see fig. 22). The area interposita is really the forming mouth of the
left venous sinus; it is from the right margin of this area that the

ey

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND, xxXi

spina vestibuli springs. The second element in the septum ovale is
the true interauricular septum—that septum which is formed on the
dorsal aspect of the primitive cardiac tube between the bases of the
auricular outgrowths. At its proximal or cephalic end it is con-
tinuous with the spina vestibuli. The spina vestibuli, starting from

Sepelal (urtersin) $.U.C,

vm. Vv
vVim_v. ‘y
Cavad ONE

Fic. 20.—An abnormal human heart thrown open. It shows all the characters
of the reptilian heart.

the inter-sinuous fold, grows forwards, as a triangular fold, until
it comes in contact with the auriculo-aortic angle, with which its
point and concave margin fuse (fig. 18). Thus the auricles are com-
pletely separated. The interauricular septum of the reptilian heart,
and of the human heart shown in fig. 20, is formed entirely by the

Xxxii PROCEEDINGS OF THE

septum oyale. To this septum Born gave the name of septum primum,
and it represents the septum superius and spina vestibuli of His.

Development of the inferior limbic band.—It will be remembered
that the inferior limbic band is attached to the central fibro-cartilage
of the heart (fig 10). That mass of fibrous tissue is developed in
the auriculo-aortic angle (fig. 18). When the spina vestibuli grows
forwards (fig. 23) it carries with it three sets of auricular fibres: (1)
those at the base of the left venous valve, (2) those in the left zner-
sinuous area (fig. 17), (3) some fibres of the left annular ring of the
left auricle. The fibres carried forwards from the left venous valve
afterwards form the inferior limbic band; they lie in part in the
fold between the coronary and caval orifices of the sinus (figs, 19 and
20). The fibres carried forwards from the left intersinuous area form
the septal band on the left vestibule.

Fic, 21.—Diagram prepared from His’s model of the ventricular segment of the
heart at about the third week of development, Through the auricular canal
is seen the interventricular foramen. The foramen represents a ring at which
growth has been nearly stationary. It is bound on the left and ventral
aspect by the margin of the interventricular septum ; on the right by the
auriculo-ventricular or auriculo-aortic angle. On the margin of the opening
opposite to the septum are developed the central fibro-cartilage and anterior
endocardial cushion.

The vestibule of the left auricle.—This is developed entirely, if one
includes the septum ovale, from the left sinus venosus. The expan-
sion of the sinus and its migration to the left is attended by four
circumstances which can be understood by comparing figs. 17, 11 and 5.

1. The dorsal or right segment of the annular basal band is carried
to the left before the sinus, and forms the left tania terminalis.

2. The septal band is pulled outwards and to the left to cover the
posterior or dorsal wall of the vestibule.

3. The left duct of Cuvier is also pulled to the left, so that it
surrounds the vestibule.

4. The migration outward and development of the sinus into the
vestibule leads to a rupture of the attachment of the septum ovale to
the aortic wall of the auricle. This break-down occurs at the part

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xxxiii

_ where the crescentic margin of the septum ovale (septum primum)
fused with the wall ofthe auricle. By this rupture is formed the fora-

men ovale, which, as Born has shown, is formed by a breaking down

_ of the septum primum.

The superior limbic band and septal fibres of the superior caval
orifice. —These are developed from the intersinuous fibres of the right
auricle (fig. 17). Some of them, too, are derived, in a way I shall
show, from the fibres of the muscular ring of the right auricle and
from the left segment of that ring. Their nature can be best under-
stood by a reference to figs. 19 and 20. In these two hearts it will
be seen that those fibres pass from the upper half of the base of the
left venous valve to the margin of the septum ovale, but many pass
into the left segment of the annular band. All these fibres formed at
first part of the annular band, and terminated by joining the right
segment of the band (right tenia terminalis) at the upper (cephalic)

Fic. 22.—An interpretation of the figure given by His of the interior of the
heart of a human embryo about 3 weeks old (Embryo Bl).

fornix of the orifice of the right sinus venosus. The migration

upwards of the sinus on the posterior wall of the auricle, owing to
the descent of the heart, has led to the spreading out of these fibres
along the base of the left venous valve.
His, quite rightly, does not mention the annulus ovalis (made up of
superior and inferior limbic bands) as forming any part of the

_ septum of the heart. Born describes its formation from what he has
_ termed the septum secundum. But it will be seen that the inferior
limbie band is part of the septum primum, and the superior limbic
_ band is part of the right annular band.

The annular bands of the primitive auricles,—These muscular rings

have been already alluded to, and are shown in fig. 17. Each ring
__ is elliptical, and made up of a lateral and mesial segment. The lateral
_ Segment of the right auricle forms the right tenia terminalis; the

mesial segment of the left forms the left tenia terminalis. The

q lateral segment of the left auricle can be seen passing round from the

c

XXXIV PROCEEDINGS OF THE

aortic angle, between the appendix and ventricle, to end on the left
margin of the left auriculo-ventricular orifice. The mesial segment in
the right auricle can be traced from the aortic angle round the aortic
wall of the right auricle, and terminates in the lowest series of the
musculi pectinati.

The aortic angle.—The aortic angle (figs. 2 and 13) is formed where
the two auricular rings fuse on the dorsal wall of the cardiac tube (fig.
17). From that point the rings diverge. As they pass forwards they
leave on each side of the attachment of the septum ovale a thin
triangular area, which can be recognised in the fully formed heart (fig.
13). These triangular areas lie against the stem of the aorta.

$ Li

Fic. 23.—Showing the formation of the septum ovale (septum superius and
spini vestibuli of His), septum primum of Born, The main element in its
formation is the spini vestibuli—a development of the sinus venosus. The
endocardial cushions are within the ventricular segment of the eardiac tube.
I have been greatly assisted by the figures given by Dr Alex. Low in the
Proc. of the Aberdeen Univ. Anat. and Anthropol. Soc,, 1900-1902.

The nature of the endocardial cushions.—We have seen that the
septum ovale completely divided the auricular segment of the
primitive cardiac tube into right and left halves. The endocardial
cushions are developed entirely in the ventricular segment of the tube.
They are derived, as His has observed, from an infolding at the
auriculo-ventricular junction of the cardiac tube.

The dorsal and ventral endocardial cushions undoubtedly represent
the dorsal and ventral auriculo-ventricular valves of the amphibian
heart. In the reptilian, avian and mammalian heart these two —
cushions or valves fuse. The dorsal cushion is constant as regards —

oT Crees one

ea.

ff ee wae Te ss i
is =!

EE ee

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND, XXxXV

its position and relationships in all hearts; but the ventral cushion
varies in its position and relationships.

In the reptilian heart the endocardial cushions are fused and are
represented by (see figs. 19 and 24) the left auriculo-ventricular valve
and the mesial right auriculo-ventricular valve. The left valve
prevents the return of the blood to the left auricle. The two valves
of the right auriculo-ventricular orifice serve two purposes: (1) they
prevent the return of the blood from the common ventricular cavity to
the right auricle, and (2) with the interventricular septum form the
orifice of the aorta. The right valve of the right auriculo-ventricular
orifice of the reptilian heart represents the auriculo-ventricular
(aurieulo-aortic) angle (see figs. 21, 23).

The reptilian and mammalian heart differ chiefly in the develop-
ment of the ventral endocardial cushion. In the reptilian heart it-
springs from the base of the left ventricle; in the mammalian heart

= 7 pr =

Rp Cham Shee qos ke te

Fie. 24.—Two diagrams to contrast the arrangement of the endocardial cushion s
in the reptilian and mammalian hearts.

it arises not only from the base of the left ventricle but also from the
auriculo-ventricular angle, and attains a more vigorous growth than in
the reptilian heart. The mouth of the aorta comes to occupy a
position to the left of the interventricular septum in the mammalian
heart (see fig. 24).

Pars membranacea septi.—There are really two membranous parts
in the septum of the heart—without taking into account the septum
ovale. One is interauricular; the other interventricular. The
interauricular is situated in the auricular wall behind the central
fibro-cartilage, and just above the base of the septal cusp of the
tricuspid valve; it marks the point at which the endocardial
cushions fused with the septum ovale. The other part is well known,
and marks the fusion of the interventricular septum with the ventral
endocardial cushion. It is separated from the interauricular mem-
branous part by only the base of the endocardial cushion. The

XXXVi _ PROCEEDINGS OF THE

aortic septal cushions do not reach down to the interventricular
membranous area; all the muscular part of the septum is derived
from the interventricular septum; I am not aware of muscular fibres
ever appearing in the aortic endocardial cushions.

The auricular appendices.—Each auricle has primarily two poles,
a cephalic and a caudal. In the cephalic pole of each ends the
tenia sagitallis. It represents cephalic prolongation of annular band
of the auricle (see figs. 17, 19 and 20). The tenia sagittalis
can always be seen in the appendix of the right auricle in man
(fig. 4). It represents the septum spurium (His). In the right
auricle the cephalic pole remains as the appendix, the caudal
disappears; in the left auricle, it is the reverse; the caudal pole
persists ; the upper, with its tenia sagittalis, disappear.

Finally.—If anyone will verify my conclusions, | would beg him,
in repeating my experiments, to observe three necessary rules:

1. That the basal attachments of the heart remain natural in position
and uncut.

2. That the chambers of the auricles are emptied of blood, by
passing a stream of water through these chambers—at blood-heat,
before any artificial or cast-taking material is injected.

3. If the ‘heat-mass’ (paraffin wax) injected is more than the
ventricles can hold, then an opening must be made in the ventricle
in order that the auricle may discharge its load and assume a state
of complete contraction.

(4) Dr Prrer THompson showed a heart in which the inter-
auricular septum presented two openings, one at the seat of the
foetal foramen ovale, and the other, one inch in front of the anterior
limb of the annulus ovalis, The specimen, which was obtained from
a male subject aged fifty-six years, is of special interest, not only
because of its rarity, but also on account of its importance in connection
with the development of the interauricular septum.

The opening at the seat of the foetal foramen ovale resembled the
most common form of patency to be observed in this situation, in
that it was an oblique slit under the annulus on the right side and
under a fold of endocardium on the left. The obliquity of the
opening was such as to prevent the passage of blood from one
auricle to the other. It was situated in the upper and left quadrant
of the fossa ovalis, and admitted a probe a quarter of an inch in
diameter. The floor of the fossa ovalis in its lower part was
irregular, and crossed by thickened bands of endocardium. A specially
developed endocardial band, under which a probe could be passed,
stretched from the posterior limb of the annulus ovalis almost
horizontally forwards, to be attached to the anterior limb.

The second opening was large enough to admit the tip of the little
finger. Situated in front, and somewhat above the level of the fossa
ovalis, and directly above the opening of the coronary sinus, it had
important relationships to the bases of the ventricles. The septal
cusp of the tricuspid orifice was immediately in front; the pars

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. XXXvii

membranacea septi was above and in front; a small intermediate
cusp, uniting the inner extremities of the aortic and marginal segments
of the mitral valve, projected into it on the left side. A feebly
developed valvular fold of endocardium passed across the lower
part sof the orifice on the left side from the marginal cusp of the
mitral valve.

$.V.G. =

Heart showing persistent ostiwm primum in the interauricular septum. The

' fight auricle has been opened in the usual manner and drawn from the

Tight side. , aorta; s.v.c., superior vena cava; F.0., fossa ovalis; 1,v-0»
inferior vena cava ; C.s., coronary sinus ; 0.P., ostium primum,

The great interest of the specimen is centred in this rare opening
in the interauricular septum. Obviously independent of the foramen
ovale, an explanation of its occurrence must be sought by a reference
to the development of the septum. The septum primum ought, in a
normal course of development, to meet and fuse with the endocardial
cushions. But whilst the process of growth towards the cushions is
taking place, an orifice—the ostium primum—intervenes between the

XXXVill PROCEEDINGS OF THE

cushions and the anterior concave edge of the primary septum, This
is subsequently obliterated, but in the specimen now described it has
persisted as a comparatively large opening, by means of which the two-
auricles are in free communication.

Whilst this seems to be the explanation of the abnormality, it is
to be remembered that the pars membranacea septi is described as
lying ‘between the aortic vestibule on the left and the upper part
of the right ventricle, as well as the lower and left part of the right
auricle on the right.”! The specimen seems to indicate that the
closure of the ostium primum may be brought about by fusion of
the upper and lower extremities of the septum primum with the
endocardial cushions, and of its intermediate portion with the pars
membranacea septi, and the ostium primum which has here persisted
occurs between the anterior concave edge of the primary septum and
the pars membranacea septi above and in front.

Arrests or abnormalities arising in the development of the inter-
auricular septum seem somewhat rare. Dr Keith showed to the
Society in June 1898 a specimen in which the septum primum had
fused with the left extremity of the auricular cavity, leading to the
formation of a large right auricle and a small left auricle. In this
case the endocardial cushions, the aortic septum and the septum
inferius were all absent.

Dr Peter Thompson also showed a specimen and lantern slides
illustrating an unusual form of mesentery enclosing small intestine,
cxcum, and ascending colon.

The specimen was found in a female subject aged 56 years, who
died in the Middlesex Hospital. For two months before death the
patient had shown symptoms of intestinal obstruction, which com-
menced a few weeks after a fall from an omnibus.

At the post-mortem it was found that the small intestine, ceecum,
and ascending colon were enormously distended, and that beyond
the hepatic flexure, at which point the great omentum was bound
down to it, producing a marked constriction, the great intestine was
collapsed. Moreover, there was a volvulus of the small intestine,
cecum, and ascending colon, and it was noticed that these three parts
were enclosed in a common mesentery, which, however, did not
extend downwards at its attached end beyond the level of the third
lumbar vertebra. This condition of the mesentery may perhaps be
best explained by a reference to its development.

At an early stage of foetal life, when the rotation of the intestinal
loop has taken place, that part of the primitive mesentery contained
within the concavity of the loop becomes the mesentery proper in the
adult, Fora time it is continuous with the primitive mesentery of
the large intestine, but subsequently the back of the mesenteries of
the ascending and descending parts of the colon undergoes adhesion
to the posterior abdominal wall and then disappears. In the specimen
now described, the mesenteric arrangement, so far as regards the
ascending colon at least, conformed to the fcetal type; apparently

' Text-Book of Anatomy, edited by D. J. Cunningham, F.R.S., p. 746.

: ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. Xxxix

there had been no adhesion to the posterior body-wall, and conse-
_-__— quently no disappearance of its primitive mesentery.

It is interesting to note the influence of the embryological factor in
: sequence of events. The injury would probably set up the local
* inflammation in the region of the hepatic flexure of the colon, result-
+ ing in the formation of peritoneal adhesions and narrowing of the gut.
: Then the ascending colon and cecum, after becoming enlarged and
g distended, were thrown transversely across the abdomen, towards the
z left, in which position they were noted immediately on opening the
q cavity. The small intestine sharing in the general enlargement
extended and filled up the right iliac fossa and right lumbar region,
passing behind the cecum and ascending colon. In this way the
volvulus would probably be initiated, and when complete would result
| in a total intestinal obstruction.
.

(5) Dr R. J. Guapstrone gave a preliminary communication on
some cephalometric data bearing upon the relationship of mental
ability to the size and shape of the head. His tables showed a distinct
P correlation between a high degree of mental ability and large size of
j head ; that the increase in size of the head was due to an augmenta-
. tion of all of its three principal diameters, namely, the longitudinal,

transverse and vertical ; and that in the adults measured, the increase
occurred chiefly in the height of the head. The tables showed, further,
that the increase in size of the head with an increase in the standard
of mental abillty was not only absolute, but also relative to the body-
-weight, the proportion of the (calculated) brain-weight to the body-
weight being greater in individuals with a high standard of mental
ability than in those in whom the standard was low. The figure
indicating this relationship of the brain-weight, to the body-weight Dr
Gladstone termed the ‘encephalosomatic index.’ The paper, with the
tables, will be published subsequently in the Journal of Anatomy and

Physiology.

(6) Professor Aexanper Macauisrer demonstrated (1) an
Egyptian temporal bone showing absence of the internal auditory
meatus; (2) a temporal bone presenting a canal for the passage of
the ninth cranial nerve; (3) a specimen in which the nerve to the
crico-thyroid muscle passed through the thyroid cartilage.

PROCEEDINGS OF THE

[ATOMICAL SOCIETY OF GREAT BRITAIN
AND IRELAND.

JANUARY 1903.

LN Ordinary Meoting of the Society was held at the Westminster
Medical School, S.W., on Friday, January 30th, at 4 p.m.
Mr C. B. Locxwoop, the President, was in the chair, and thirteen

membe rs and two visitors were present.
abel tf.
Eat Me “The minutes of the last meeting were read and confirmed.
meals

following gentleman was unanimously elected a member of the
- Society:—Ricnarp A. Sronsy, M.B., Senior Demonstrator of
- Anatomy, Trinity College, Dublin, spnead by D. J. Cunningham,

-* Birmingham, and Peter Thompson.

Specimens and Papers :—

“ae Mr F. G. Parsons read a paper On the Meaning of Some of the
Centres of Ossification. This paper will be published in
-extenso in the June number of the Journal of Anatomy and

ty,

(2) Mr F. G. Parsons ies gave a short communication On the
Sabdeator Tertius Muscle of Ungulates. He pointed out that this
Roman was originally described by Drs Mivart and Murie in the
=: and has since then been noticed in several other ungulates. __

t rises from the internal (pelvic) margins of the obturator foramen,
and passes through that foramen to be inserted into the digital fossa
of the femur. From a series uf dissections of ungulates carried out in
- conjunction with Professor Windle, he was convinced that this is not
a separate muscle, but part of the obturator externus, which has
_ pushed its way inward through the obturator foramen, and has stolen

d

xlii PROCEEDINGS OF THE

the normal attachment of the obturator internus. His reasons for
this conviction are (1) that it is inseparable from the obturator ex-
ternus outside the pelvis; (2) that the delicate obturator membrane
is to be made out pushed inward in front of it; and (3) that the
obturator nerve supplies it. It appears that the muscle is present in
this form in the Artiodactyla and Hyrax (Procavia), but not in the
Perissodactyla. He did not at present know whether it is to be
found in the Cervidee or Elephantide.

(3) Homologies of the Sense Organs. By Joun Cameron, M.B.,
M.R.C.S. (Abstract.)

The question of the homologies of the various sense organs has
been keenly discussed, and there is still much doubt regarding the
comparison of the different parts of the sense organs with one
another. In Quain’s Anatomy (vol. iii., pt. iii., p. 152) it is stated
that the ganglion cells on the posterior roots represent the sense
epithelium, such as we find in the olfactory organ and in the retina of
the eye. The result of this would be to ignore the stratified
epithelium of the skin altogether, and consider it as having nothing
to do with the reception of tactile impressions. A little further on
in the same page of this work, the cells of the spinal ganglia are
compared to the specialised cells which are found lying between
the epidermal cells of lumbricus, and whose short distal processes
end on the free surface, while their long central processes arborise
around ganglion cells. The mode of development of the spinal
ganglion cells is sufficient to oppose this theory, for they always
remain close to the developing nerve centre, and their distal pro-
cesses grow towards the periphery, and, moreover, never reach to
the free surface, but ramify amongst the cells of the stratum Malpighi.
The cells of lumbricus resemble more highly specialised epithelium
cells, such as the vertebrate olfactory cells, and the latter are the
only sense epithelium cells of vertebrates, which develop in such a
manner that their distal processes remain on the free surface, while
their proximal processes grow towards the nerve centre. The writer
would thus look upon the cells of the stratum Malpighi as the
tactile sense epithelium, and this view is supported by the fact that
the epithelium of the touch corpuscles is developed from the
epidermis.

Four stages may be noted in the reception and transmission of
tactile impulses. There is, firstly, the sense epithelium, which is
represented by the stratum Malpighi. The second stage is formed by
the spinal ganglion cell, with its distal and central processes. There
is, thirdly, the stage of relays within the nerve centre (nucleus
gracilis or cuneatus and optic thalamus). The cerebral cortical cells
constitute the fourth and last stage.

The sense epithelium for hearing consists of the auditory cells,
which are developmentally homologous with the cells of the epi-
dermis. The cell of stage ii. is situated in the spiral ganglion, and,

like the spinal ganglion cell, it is formed from the neural crest. The

nidh

. =a

,

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xliii

stage of relays consists of the accessory nucleus or tuberculum
acusticum, and the median geniculate body, posterior corpus quadri-
geminum or superior olive. Stage iv., the same as above.

The gustatory sense epithelium is found in the taste-buds. The
‘writer considers the cell of stage ii. as being situated in the Gasserian
ganglion, and, if this be so, it corresponds developmentally with the
cell of stage ii. in the tactile and auditory senses. Stage iii. consists
here of one relay in the vicinity of the fourth ventricle and one in
the optic thalamus (both are hypothetical). Stage iv., the same as

ve.

The olfactory cells are, as regards their development, homologous
with the auditory and epidermic cells. Stage ii. is represented by
the mitral cells of the olfactory bulb. -With regard to stage iii.,
Elliot Smith finds that in monotremes there is only one relay (fimbria,
fascia dentata, septum lucidum or peduncle of corpus callosum).
Stage iv., the same as above. There has always been a difficulty in
comparing the retina with the other sense organs, on account of the
numerous layers in the former. The writer has found, however, that
in the chick and tadpole, some of the bipolar cells of the inner
nuclear layer migrate through the external molecular layer, and
become transformed into rod and cone cells, and on this account the
inner and outer nuclear layers of the retina together correspond to the
epithelium of the other sense organs. Stage ii. is formed by the
retinal ganglion cells, There is only one stage of relays (lateral
geniculate body, pulvinar or superior corpus quadrigeminum). Stage
iv., the same as above.

On reviewing the subject generally, it will be observed that the
arrangement throughout the different stages in the tactile, auditory
and gustatory senses is very similar. The sense epithelium cell has
no central process, the cell of stage ii. is practically the same in all,
and stage iii. consists of two relays within the nerve centre. The
arrangement for the olfactory and visual senses also agrees very
closely. The sense epithelium cell possesses a central process, the cell
of stage ii. is somewhat similar (multipolar) in both cases, while in
stage iii. there is only one relay within the nerve centre.

(4) Mr N. Bisnor Harman showed a brain and lantern slides
exhibiting the effects presumed to be produced by a bullet wound of
the brain in a man, as determined by its experimental production in
the cadaver.

A soldier was shot in South Africa whilst asleep. The bullet (a
small gauge hard-cased missile) entered by the parietal bone 24 in.
from the ext. angular process, and 4{ in. up from Reid’s base line,
and escaped through the occipital bone 1 in. up from the ext.
occipital protuberance, and } in. to the left of the median line.
The man was unconscious for a fortnight; recovered with right
paraplegia and right homonymous hemianopsia, the paresis diminished
until there remains only some weakness of the right arm, the field of
vision had not changed, but central vision was full.

xliv PROCEEDINGS OF THE

The head of a cadaver, the proportions of which were ascertained
by the usual anthropometry to coincide with those of the patient's,
was injected with formaline shortly after death. The wound sites
were found, trephined, and from hole to hole a stylette passed, and
over it a tube of the size of the bullet pushed.

Examination of the skull showed that neither meningeal vessels of
any size nor any venous sinuses were damaged. The probe entered
the brain in the ascending parietal convolution just below the level
of the sup. frontal sulcus, and, passing under the supra-marginal
convolution, angular gyrus, and middle occipital convolution, escaped
at the posterior inferior junction of the last with the cuneus. Sections
showed that the wound had dominated the grey areas of these regions
in a remarkable manner, besides penetrating the greater part of the
occipito-thalamic radiation. The position of the entrance wound and
the transience of the motor paresis was thought to lend support to
the new localisation of the motor area in anthropoids by Sherrington
and Griinbaum. The hemianopsia was fully accounted for by the
destruction of the occipito-thalamic radiation. A feature of the
fields of vision was a rim of blindness on the left side of the left eye ;
it was thought this might suggest some lesion of the right hindpart
of the cuneus near the middle occipital convolution, by reason of the
nearness of the site of the wound of exit to this area.

(5) On a Case of Congenital Cardiac Malformation. By Dr F. H.
Turete. (This specimen was exhibited before the Society in
November 1901.)

Clinical History.—The patient from whom this heart was obtained
was a boy three and a half years old. He was admitted to University
College Hospital under the care of Dr S. Martin, suffering from
broncho-pneumonia with a great deal of cyanosis.

The mother stated that prior to his illness he never was ‘blue,’
but that he was unable to run about like her other children.

A loud systolic murmur was heard, having its maximum intensity

at the pulmonary cartilage. The murmur was heard over the whole

cardiac area.

| Description of the Heart.—The heart is divided into two auricles
and two ventricles, the auricles communicating with one another by
a wide orifice, and the ventricles by a minute opening at the un-
defended spot.

The right auricle receives the superior and inferior ven cava
together with the coronary sinus, The right ventricle gives off the
aorta from which the coronary arteries arise. The branches from the
aortic arch are normal in number and relation, and there is no com-

munication between the aorta and the pulmonary artery. ‘The left

auricle receives the four pulmonary veins, and the left ventricle gives
off the pulmonary artery.

' The Cavities of the Heart in detail.—The right auricle is a large
cavity, having a diameter of just over 2°5 cm. The auricular
appendix is a large muscular process, and has the normal relations;

Sn ee ee oe

a

a — =
hd ede “ee oie

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xlv

The opening from the auricle into the appendix is 2 em. wide, and
the appendix is 2°5 cm. long. The average thickness of the wall of

the appendix is 25 mm. Entering the auricle just above and behind
the auricular appendix is the superior vena cava, below is the inferior
vena cava. There is a well-marked delicate Eustachian valve from
which a slender filament runs to the Thebesian valve, uniting the
free edges of the two valves. The opening of the coronary sinus is in
its normal position. The inter-auricular septum is incomplete at the
upper part, the deficiency in the septum being one centimetre in

t. This deficiency is divided by a thin vertical band into a
posterior smaller and an anterior larger area. Below the opening the
floor of the fossa ovalis is formed by a firm cribriform membrane,
which membrane is funnel-shaped, the closed apex of the funnel at
the autopsy projecting into the right auricle.

The right ventricle has a cavity 7 cm. in length and 2-5 em in
transverse diameter. The average thickness of the wall is 1°5 cm.,
and the heart’s apex is formed by the right ventricle. The auriculo-
ventricular valve is tricuspid ; the musculi papillares have the normal
arrangement. The valve and the chorde tendinee are thicker on
this side than on the left side of the heart, but the reverse is the case
with the musculi papillares. At the highest part of the cavity is
the aortic orifice, separated from the auriculo-ventricular orifice by an
infundibulum 30 mm. long. The upper wall of the infundibulum is
formed by the muscular prominence which is named by His the
supraventricular crest, and which, in the normal heart, contains the
beginning of the aorta, but in this case lodges the pulmonary artery.
The aorta arises in front of and rather to the left of the pulmonary
artery, passes upwards and backwards above that trunk to form the
arch in the usual position above the root of- the left lung. The
vessels arising from the arch are normal in arrangement. The two
coronary arteries arise from this trunk from the Sinuses of Valsalva
over the posterior and left anterior aortic flaps. There is a normal
aortic valve with three semilunar flaps, which appear to be right and
left anterior and one posterior. The minute interventricular opening
is placed under cover of the anterior corner of the septal flap of the
tricuspid valve.

The left auricle is much smaller than the right, and its wall is
about 15 mm. in thickness. Its appendix is long, narrow, and
tortuous. ‘The four pulmonary veins open into the auricle in the
normal way.

The left ventricle is smaller than the right, its cavity being 5 cm.
long and 2 cm. wide, and the wall is 6 mm. thick. It gives off the
pulmonary artery, which arises behind and rather to the right of the
aorta. Its divisions are normal, and there is no sign of the ductus
arteriosus being patent. The pulmonary valve is normal, with three
semilunar flaps, which appear to be an anterior and right and left

rior. The pulmonary trunk is directed backwards and to the
right behind the origin of the aorta and the infundibulum of the
right ventricle; and somewhat to the right of and below the aortic

xIvi PROCEEDINGS OF THE

arch it divides into the usual two branches. The lungs are normal,
the right lung having three lobes and the left two. The left auriculo-
ventricular valve is bicuspid, but is not so strong as usual, and not so
strong as the valve of the right side, though the papillary muscles
are stronger. On this side the interventricular opening is placed
3 mm. below the attached margin of the right posterior flap of the
pulmonary valve and a little behind its centre. This opening is
clearly in the undefended spot, and will only admit a fine bristle.

Similar cases are recorded in the second edition of Dr Peacock’s
Malformations of the Human Heart. He quotes from Virchow’s
Archiv. of Path. Anat. and Phys., 1857, vol. xii. p. 364, a case of
Friedberg’s, in which the foramen ovale was open, the ductus Botalli
and the septum of the ventricles closed. Another case was published
by Dr. Cockle in the Medico-Chirurgical Transactions, vol, xlvi.
p. 193. ‘In a male child, which survived two years and eight
months, and was cyanotic. Septum of ventricles entire, foramen ovale
completely open, ductus arteriosus obliterated. The aorta arising
from the right ventricle and the pulmonary artery from the left.”

There are numerous other cases recorded of transposition of the
aorta and pulmonary artery, but in these cases, with the exception of
the two quoted above, either the septum between the ventricles was
more or less incomplete, or the ductus arteriosus was patent. In
other cases, not only have the arteries been transposed, but the
ventricles also, as was indicated by their relative size and the form of
the auriculo-ventricular valves.

The mode of origin of this abnormality may, I think, be explained
by an abnormal rotation of the septum of the common arterial trunk.
According to His, this septum is formed by two ridges projecting into
the common tube. These ridges are so placed that at the upper end
they are disposed sagitally, being anterior and posterior, so that the
resulting tubes are side by side; at the lower end the ridges right
and left, and the tubes, are anterior and posterior. The meeting of
these ridges and the consequent formation of the tubes occurs from
above downwards. Now, in the normal condition, if we imagine the
upper end to be the starting position of the septum, it will be seen
that the anterior margin of the septum above comes to be the right
margin below, and thus the septum rotates through 90° in the direc-
tion of the hands of a watch. Accordingly, at the upper end, the
two vessels lie side by side, the aorta being to the right, the pul-
monary artery to the left, and tending to pass behind the aorta. At
the lower end, the pulmonary artery lies in front of and a little to
the left of the aorta.

The condition of things and the mode of rotation of the septum
will be seen from the accompanying diagrams, which represent
sections of the arterial trunks at different levels. (Diag. A.)

In the specimen here described there exists at the upper end the
same arrangement of vessels as in the normal, whilst at the lower end
the aorta arises in front of and a little to the left of the pulmonary
artery. This may be explained by rotation of the septum in the

_—

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xlvii

opposite direction, viz., 90° contrawise to the hands of a watch, and
thus the anterior margin of the septum above is turned to the left
below, instead of to the right, as in the normal.

" (2)

Fi >
by TM
| RF
Aan

lly

“WEN

(S)

DIAGRAM A.

Fig. 1 —- highest, and fig. 5 the section just above the heart. A. repre-
sents the aorta ; P. the pulmonary artery ; (a, )) the septum—(a) being the
anterior, ()) the posterior margin.

tia

ANTM
f

AM iG

AW
S

(5)

DracraM B.

xIvili - PROCEEDINGS OF THE

A similar series of diagrams to the above, with the same lettering
and arrangement, indicates this (diag. B), and by this means the aorta
comes to lie in front of the pulmonary artery.

The rotation of the septum in the two cases is shown in the
following diag. C.

Normal. In this case.

; 3

DIAGRAM C,

This abnormality also finds a place in Rokitansky’s scheme.
According to him, the common arterial trunk is divided into the two
great trunks by an asciform septum, which is so placed that its con-
vexity lies forwards and to the left. Thus in (1) diag. D, ss’ is the
septum, (P) the pulmonary artery, and (A) the aorta, Now, by
alterations in the position of the septum, the relative positions of the
vessels may alter; thus, if ss’ of (1) be conceived rotated through
180°, the position of the vessels occurring in this specimen is obtained,
as is represented in (2) diag. D, the aorta lying in front of and to the
left of the pulmonary artery. This will account for the transposition
of the vessels. According to Rokitansky two conditions may exist
with transposed vessels :—

1. The transposed vessels may open from physiologically incorrect
ventricles.

2. The vessels may open from physiologically correct ventricles,

Case | he calls uncorrected transposition.

Case 2 he calls corrected transposition.

These results, according to Rokitansky, are due to variations in the
position of the attachment of the ventricular septum to the vessels.
This septum he supposes to grow upwards towards the arterial septum,
and in its direction. It is normally inserted into the anterior and
left part of the aorta, whence it encircles the right side of the vessel ;
the pars membranacea continues this attachment along the border of
the posterior flaps, and is inserted into the diametrically opposite
point in the aorta. In any anomalous position of the two vessels the
pars membranacea always lies along the convex border of the posterior

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. xlix

vessel, either along its right or left side, no matter whether it be the
aorta or pulmonary artery.

Thus if it pass to the right of the posterior vessel, that vessel will

be relegated to the left ventricle ; if to its left, then the vessel will
arise from the right ventricle. The septum rarely passes to the same
side of both vessels.
' Thus in diag. E, modified from Rokitansky’s figures, in (1) we
have the normal condition of things, the septum being inserted into
the anterior and left part of the aorta and the pars membranacea
along the right border of the aorta. In (2) we have transposition of
the vessels with normal arrangement of the septum, and so we get
‘uncorrected’ transposition, and this is what has occurred in the
specimen now described.

In (3) diag. E the pars membranacea passes along the left of the
posterior vessel, and this is Rokitansky’s ‘corrected’ transposition of
the vessels, of which there are several cases recorded.

eS

Dracram D,

] ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND.

POSTERIOR. POSTERIOR.
<= LE = Sv

SS += — —
LSS ——S= SS

(1) an7erIoR. (2) ANTERIOR.

= a
— LS

(3.) ANTERIOR.

Diag. A is copied from His’ Menschliche Embryonen. TD and E
are after Rokitansky.

I have to tender my best thanks to Prof. 8. Martin for permission
to publish the case, and to Prof. G, D, Thane for his valuable advice
as regards the specimen.

apse. 3

3
rf
“
.-
4

«* @y
“~

PROCEEDINGS OF THE

ANATOMICAL SOCIETY OF GREAT BRITAIN

AND IRELAND.

MAY 1903.

An Ordinary Meeting of the Anatomical Society of Great Britain
and Ireland was held at the London Hospital, Whitechapel, E., on
Friday, May Ist, at 4 p.m. Mr C. B. Lockwoop, the President, was
in the chair, and seventeen members and four visitors were present.

The minutes of the last meeting were read and confirmed.
Specimens and Papers :—

(1) Contributions to the Human. Mechanism of Respiration.
By Arruur Keirs, M.D:

The manner in which the apices of the lungs are expanded and
filled with air is a matter of the utmost clinical importance. While
it is probably true that their susceptibility to tuberculosis is due to
an imperfect expansion or inflation with respiratory air, yet no
satisfactory explanation has been offered of their imperfect expansion
or inflation. Wherein lies the defect in the inspiratory mechanism ?
The following observations deal first with certain neglected points
in the structure of the upper part of the thorax which have to do
with the expansion of the apices of the lungs.

The sterno-manubrial joint.—The movements at this joint may
be studied in the following three ways: (1) In the living by applying
two small reflecting mirrors (} inch diameter), one over the manu-
brium, one over the mesosternum, and throwing their reflections on
a screen at a fixed distance from the person examined. The easiest
manner of fixing the mirrors to the sternum is by mounting them
on small rubber bell-like ‘ suckers,’ such as are used for fixing objects
to the glass of shop windows. Mirrors mounted in this manner serye
to demonstrate the movements of the heart if placed over the area
of cardiac impact. (2) The movements of the joint may be measured

J

lii PROCEEDINGS OF THE

in life by using a minute pendulum. By means of two rubber suckers,
such as are mentioned above, two levers are attached, one at
right angles to the manubrium, the other to the mesosternum ;
from the point of each lever a minute pendulum is suspended, the
ball of which swings in front of a scale graduated in degrees. These
may be applied either in the lying or standing posture. (3) The
movement may be studied and measured after death by performing
artificial respiratory movements in the right or left half of a thorax
from which all the parts, save the ligaments, have been removed.
By applying the cut or mesial surface of such a thorax to a wide
board, and fixing the spinal column to the applied surface by nails,
tracings of the sternum in various stages of a complete respiratory
movement may be obtained.

The extent of movement at the sterno-manubrial joint.—The extent
varies with the individual, with the sex, with disease, with the type
of respiration, and with the degree of the respiratory act; but the
essential fact concerning it is that there is no elevation or headward
movement of the primate sternum possible without a movement at
this joint. In a collie dog, which submitted voluntarily to an
examination, there was no movement at this joint, but in it there was
no forward or headward movement of the sternum ; in this particular
dog the movement of the sternum was one of pure rotation, the
abdominal end rotating downwards and forwards in placid respiration
4° to 6°.

The following were the movements at the sterno-manubrial joint
as measured by the rotation of the anterior surface in five individuals
—-two men, one woman, two children—all in a state of health :—

Manubrium. Mesosternum.
Moderate Full Moderate Full
Inspiration. Inspiration. Inspiration. Inspiration.

Man A, . 2-3° upward 13-14° upward 1-2° downward 3-4° downward
Man B, . 1-2 ee 6-7 a no rotation 1 ms
Woman, . 3-4 os 12-14 __—s=,,, 2-3° upward 6-8 upward
Children
(6-8 years) ¢ 7258 » 4-5 oF) 1-2 ” 3-4 9

Thus in complete inspiration the degree of movement at the sterno-
manubrial joint was as much as 18° inman A; in the woman, although
the actual rotation of the manubrium was as great as in man A,
yet the movement at the sterno-manubrial joint was only 6°, owing
to the mesosternum undergoing a rotation in a direction similar to
that of the manubrium.

The function of the sterno-manubrial joint.—In estimating the part
this joint plays in the inspiratory expansion of the lung, one has to
consider the significance of (1) the width, the strength, the early
liability to ossification of the first costal cartilage and its direct
continuity with the manubrium; (2) the peculiar shape of the first
rib; (3) the peculiar costo-vertebral articulation of the first rib;
(4) the attachment of Sibson’s fascia, the subclavian and innominate
veins to the first rib, Taking all of these points into consideration

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. liii

go that their functional meaning may be explained, and by observing
the respiratory movement in the living, one must conclude that the
manubrium sterni, the first pair of ribs and their cartilages, with

: Fe Sibson’s fascia, form a functional lid for the thorax, and move as if

they formed one piece. The lid is hinged to the vertebral column at
the first costo-vertebral articulation ; its movable or swinging end is
attached to the anterior wall of the thorax at the sterno-manubrial
joi The anatomical and physiological apex of the lung lies
above the level of the upper border of the second costal arch.
The inspiratory expansion of the apex of the lung.—Since the
vertebre and the vertebral segments of the ribs (defining the vertebral
t of a rib as that part which is covered by the erector spine
or its prolongations) encroach on, rather than enlarge, the cavity of
the thorax during an inspiratory movement, there can be no
expansion of the apex of the lung in a backward direction. In
considering the expansion of the apex in a forward direction, one
must remember (see fig. 1) (1) that it slopes downwards and forwards

Fic. 1.—A figure to show the relationship of the first rib and manubrium sterni
to the apex of the lung (1) in expiration, (2) in inspiration.

from the neck of the first rib to the upper border of the second costal
cartilage ; (2) that on this sloping surface there are placed Sibson’s
fascia, the first rib, the subclavian artery, and the subclavian vein, all
of which form the thoracic lid. The lid is hinged behind ; when its
anterior part is lifted up on inspiration, it is the anterior part of the
apex that feels the movement; the posterior part lying in front of
the neck of the first rib, being nearer to the axis of movement, is
only affected indirectly (see fig. 1). The lowest trunk of the brachial
plexus crosses the first rib almost in the axis of the movement, and is
but little disturbed. Thus the upward movement of the thoracic lid
_ is not effective in causing an expansion of the dorsal part of the

apex of the lung.

If, however, one turns to the lateral expansion of the thorax, a
more effective and direct agent for bringing about the expansion of

liv PROCEEDINGS OF THE

the lung will be found. In fig. 2 is represented the characteristic
‘bucket-handle’ movement of the five upper ribs—a movement
peculiar to the upper five ribs. In this movement the bow of the
costal arc is elevated on an axis joining the spinal and sternal
extremities. This movement brings about a direct lateral expansion
of the apex of the lung, but it will be noted that the part of the

unspur,
Expir.

ee

\
}
!
if

ee ic er eee eee

Fic. 2.—The right half of a thorax viewed from behind. The position and out-
ward expansion of the lungs during inspiration are shown by dotted lines,
The lateral expansion is seen to be obtained by the movements of the upper
five ribs,

apex in front of the neck of the first rib is the least affected by this
movement.

There is still one other direction in which the apex of the lung may
expand, and that is towards the diaphragm or floor of the thorax. In
the quiet abdominal type of respiration the diaphragm is certainly the

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. lv

principal agent in causing an expansion of the apex. A respiratory
contraction of the diaphragm causes a descent of the whole lung, the
basal part being first affected and moving most, the apical part being
last set in motion and moving least.

Thus it will be seen that of the three forces which may cause an
expansion of the apex of the lung, one of them only, the upward
rotation of the costal arcs, acts directly ; while the other two, the
upward movement of the thoracic lid and the downward movement of
the diaphragm, act only indirectly. Further, that it is the dorsal part
of the apex of the lung, that part which lies in front of the neck of the
first rib and first intercostal space, that has the least effective provision
for its expansion of all the parts of the lung.

Certain unexplained points in the structure of the lower siz
costal arcs.—In teaching the structural mechanism of respiration,
one feels the necessity, in order to make the matter simple and easily
understood, of treating the costal movements, which lead to an
enlargement of the thorax, as if they were the same in each rib.
Yet all of those who have paid special attention to this subject have
noticed that each rib has its own peculiar combination of movements,
has its peculiar articulations and its peculiar shape; ‘but, as a rule, these
individual features are dismissed as of no real import in practical
medicine.’ There is, however, one series of adaptational structural
points which characterise the second, third, fourth, and fifth pairs of
ribs, and another series which are found in the seventh, eighth, ninth,
and tenth pairs, while the sixth pair is always intermediate in structure
to the upper and lower costal sets (see fig. 3). I am unable to offer
a full and adequate explanation of the differences of structure between
these two sets of ribs, but I wish to place them on record here, because
their significance will certainly become apparent to whoever succeeds
in mastering the true movements of the ribs. The same distinction
in structure between the upper and lower sets of ribs is to be seen in
the thorax of all orthograde primates.

In the upper set of ribs (second, third, fourth, fifth), when
the thorax is viewed in profile, each rib is seen to be _ bent,
with its lower margin showing a convexity from the angle to the
¢costo-chondral junction (fig. 3); the convexities are directed down-
wards to the sixth rib. In the lower set (seventh, eighth, ninth, tenth)
the upper border is convex, the convexity being directed upwards to
the sixth rib (fig. 3).

One explanation of this is to be found in fig. 2. The upper set of
ribs is seen to be raised by a ‘bucket-handle’ movement, and thus
expanding the chest laterally. ‘The lower set undergo no such move-
ment; they are long levers articulated at their vertebral ends ; when
their ventral ends are raised, they lead to a great lateral enlargement
of the abdominal wall, but only to a very partial lateral enlargement
of the real pulmonary space. That is to say, while the upper set of
ribs are direct lateral distenders of the lung, the lower set is made
accessory to the diaphragm. They provide a fulcrum for the diaphragm ;
their lateral movement is designed to make room for the abdominal

lvi PROCEEDINGS OF THE

viscera displaced by the diaphragm rather than to cause a direct.
enlargement of the lung.

The upper and lower costo-transverse articulations.—As is well
known, the costo-transverse articulations of the upper and lower sets
of ribs show a marked difference in form, but the meaning of this
difference is not easy of explanation. In the upper set the articular
facet on the rib is oval and convex, as if it were the segment of a
cylinder ; while the facet on the transverse process is socket-shaped,
so as to receive the costal articulation (fig. 4). In the lower set of ribs.
the costal and transverse facets are flat and oval (fig. 4). The costo-

Fic. 8,—A drawing of the fifth and seventh ribs of the right side in situ, to show
the differences in shape which distinguish the upper and lower sets of ribs.

transverse articulations of the sixth rib are intermediate in character.
What is the explanation of this difference? In the first place, the iower
set is acted on by the diaphragm, while the upper set is not; the upper
set undergoes an upward rotation round a sterno-vertebral axis, while
the lower does not.

The axis round which the ribs rotate-—The most accurate repre-
sentations of the respiratory movements of the ribs are those given by
Thane in Quain’s Anatomy, vol. ii. part ii. p. 161 (ed. 10). The
axis of rotation there shown passes through the neck of the rib; for
all practical purposes such an axis may be accepted as correct. But
it is not absolutely correct. On comparing horizontal tracings of the
thorax, taken by narrow plates of lead during life, I was struck by

ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. lvii

_ the forward movement of the vertebral segments of the lower ribs
(fig. 5). In over half of the subjects I investigated—nine in all—the

_ thorax underwent a diminution on its dorsal wall instead of an

_ enlargement during inspiration. On examining the movements of the

ribs on an artificially prepared thorax, in which the life-movements
were imitated, that part of the rib on which the tubercle is situated
was found not to be part of a stationary axis, but underwent during
inspiration a movement forwards and downwards, so that, at the end
of an inspiratory movement, the tubercle, and segment of the rib on
which the tubercle is situated, occupy a lower and more ventral
position in relationship to the transverse process than at the com-
mencement of the inspiratory act. Further, most writers on this

Cos&~ amev. artic.

Fic. 4.—The costo-transverse articulations, as seen in section, of the fourth and
ninth ribs.

subject overlook the fact that the ilio-costalis is attached to the ribs,
and actively or passively must be concerned in the respiratory
movements of the ribs. The ilio-costalis is attached only to the
lower set of ribs—those with the flat oval costo-transverse articulations
to which the diaphragm is also attached, and which undergo a slight
downward and forward movement at their vertebral segments.

The ilio-costalis as a respiratory muscle.—So far as | know, no one
has ever offered any explanation of the peculiar arrangement of the
outer column of the erector spins, or attached any meaning to its
relationship to the ribs. On attempting to imitate in a large model
the respiratory movements of the seventh rib, I found that unless a
stay were attached to the rib at its angle, so as to represent the ilio-
costalis, the movement obtained from the external intercostal sheet

lviii PROCEEDINGS OF THE

of musculature was one similar to the upper ribs—namely, a ‘ bucket-
handle’ movement—attempting thus to give a lateral expansion of
the chest. But, on applying to the rib a cord attached at its angle
so as to represent the ilio-costalis, | could produce in the model an
exact copy of the normal movement of the lower ribs. The further
evidence, perhaps not of great weight, may also be stated: that a hand
placed over the ilio-costalis during full or moderately full inspiration
feels that muscle to harden as if then in increased action. Further,
in people who have suffered from rheumatoid arthritis of the costo-
vertebral articulations, the pathological heapings of bone at the

Fic. 5.—Horizontal tracings of the right half of the body of two individuals in
expiration and inspiration. The tracings were taken at the level of the
ninth dorsal vertebra and xiphi-sternal joint. The two individuals repre-
sented in the figure show a marked difference in the degree of flattening
in the posterior wall of the thorax during inspiration,

margins of the costo-transverse articulations could only be accumulated
if a forward and downward movement occurred at the costo-transverse
articulation during inspiration. The upward convexity of the lower
set of ribs, as seen in a profile of the thorax (see fig. 2), is evidently
the result of the insertion of the ilio-costalis to this set; the ilio-
costalis provides a movable fulcrum for this set of ribs. The ilio-

Jem ___ ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. lix

__ eostalis is neither a muscle of inspiration or expiration ; it is in action
_ steadying the lower ribs during both acts, but its exertion is greatest

during inspiration. The accessorius unites the lower or diaphragmatic

set of ribs to the upper, on which it acts as a muscle of expiration.

_ The cervicalis ascendens, as far as it is respiratory in function, is the

Lae ee

tory opponent of the expiratory accessorius.

The interchondral articular facets——What is the meaning of the
articulations which are found between the sixth, seventh, eighth, and
ninth costal cartilages? Out of nineteen bodies I examined, thirteen
had, besides the articulations between the sixth, seventh, eighth, and
ninth, also one between the fifth and sixth. These facets are to be
‘seen in the fifth-month foetus. In the great anthropoids the sixth,
seventh, and eighth cartilages come together, and synovial facets are

found, but the great heels of cartilage which are thrown out at these

articulations are found only in the human thorax. There are neither

- facets nor heels, nor direct contact between the cartilages, in any of

the pronograde primates.

The explanation of these interchondral facets offered by Hermann
von Meyer in the Archiv fiir Anatomie, Anat. Abth., 1885, p. 277,
is, I believe, the correct one—viz., that through these interchondral
articulations the diaphragm may exert its lifting force on ribs above
those to which it is attached.

The three segments of a costal arc.—A prolonged examination
of the respiratory mechanism of reptiles, birds, and mammals has
convinced me that in all forms each complete costal are constantly
shows three segments, each of which has its physiological significance.

Each of these segments bears a definite relationship to the corre-

sponding segment in the costal arc in front of it and behind it. The
three segments are dorsal, lateral, and ventral.. The /orsal is that
covered by the erector spine; the ventral is represented by the
costal cartilages, the lateral by the intermediate section of the arc,
between the dorsal and ventral. The ventral segments invariably
increase in length and obliquity in passing from the cervical to the
abdominal border of the thorax. The same law holds good for the
dorsal segment, except that in primates the dorsal segments of the
middle ribs are the least sloping ; in approaching the cervical border,
as in passing towards the lumbar border, the inclination towards
the spine becomes increasingly marked. As regards the inclination
of the lateral costal seyments, they also become more oblique in
position as one passes from the cervical to the abdominal border of
the thorax. In primates the lateral costal segment increases in
length up to the sixth, or occasionally to the seventh rib; beyond

that it rapidly declines, this segment being only partially represented

in the eleventh rib. Thus each half of the thorax may be regarded
as made up of a dorsal, lateral, and ventral zone.

The meaning of the three zones of the thorax.—lf the meaning of
the three zones of the thorax be correctly grasped, a much clearer and
truer conception of the mechanism of respiration will be obtained
than by any other manner of regarding the costal series. Taking

lx PROCEEDINGS OF THE

first the meaning of the lateral segment, it will be seen that it is
concerned with the increase of the antero-posterior diameter of the
thorax. Since the ribs decrease in length after the sixth or seventh,
then during inspiration, when the lower ribs are elevated, the antero-
posterior diameter of the lower part of the thorax is decreased—a fact
which may be verified in life. The increase of obliquity from above
downwards was correctly explained in the classical work of

Hutchinson. The external intercostal muscles which lie between the ©

lateral costal segments, the scalenus medius and anticus, are the
inspiratory muscles of the lateral segment of the thorax. Since the
parts of the external intercostal sheet of muscle between the upper
intercostal spaces have the greater resistance to overcome in inspira-
tion, they have also a greater mechanical advantage in the more
horizontal position of the upper ribs. The muscles of expiration of
the lateral zone of the thorax are (1) that part of the internal oblique
inserted to the ninth, tenth, and eleventh ribs ; (2) the internal inter-
costals between the lateral segments of the ribs; (3) the external
oblique. In normal respiration all these muscles are constantly in
action—the inspiratory overcoming in inspiration, the expiratory in
expiration.

The dorsal and ventral segments of the costal arcs are concerned
with the increase of the transverse diameter of the thorax, and are so
arranged as to bring about this effect. The inspiratory muscle of the
ventral segment is the intercartilaginei ; the expiratory, the triangularis
sterni and rectus abdominis. ‘The inspiratory muscles of the dorsal
segment are the exceeding strong external intercostal sheet between the
dorsal segments of the ribs, the levatores costarum, the scalenus
posticus, the serratus posticus superior, the cervicalis ascendens ; and
perhaps the ilio-costalis should also be added. The expiratory
muscles of the segment are the accessorius, serratus posticus inferior,
and quadratus lumborum. By thus separating the thorax into three
zones, one obtains a rational explanation of the arrangement of the
respiratory muscles, and an easy way of teaching the mechanism of
respiration.

The mechanism of respiration in the orthograde primates contrasted
with that in the pronograde primates,—That in man, as in the
anthropoids, the thorax is peculiar in shape, the ribs peculiar in their
curvatures and flatness, the sternum peculiar in its breadth and
shortness, constitute a series of well-recognised facts. Probably,
too, one may accept as approximately true that all of these characters
are in one way or another a result of the orthograde posture. No
one, so far as I am aware, has ever sought to interpret the meaning of
these anatomical characters in so far as they indicate a modification
in the manner of respiration. Here I merely wish to contrast a list
of the points in which respiratory mechanism of the orthograde
primates differs from that of the pronograde. As far as regards the
general arrangement and composition of the three zones of the
thorax just described, the one form agrees with the other ; also in the
arrangement of the intercostal muscles they agree. .

I. As regards the Dorsal Zone of the Thorax.

ss Orthograde Primates. Pronograde Primates,
_ @. Posterior costo-transverse ligaments, a, The posterior costo-transverse liga-
_ fibrous in structure. ments are composed of yellow

aes elastic tissue in the lower six ribs.
4 Quadratus lumborum, a wide sheet 6. Quadratus lumborum, narrow series

_ with ilio-costal fibres. of inter-transverse fasciculi, no
ilio-costal fibres being present
in it.

If. As regards the Lateral Zone of the Thorax.

f. a. The scalenus medius ends on first «. Scalenus medius, strong inspiratory
Roa, ‘Fab. muscle reaching to the fourth or

a fifth rib.
__ b. The external oblique tothe eleventh 6. The external oblique has no origin
* and twelfth ribs has an origin from the iliac crest.

from the iliac crest.

IIL As regards the Ventral Zone of the Thorax.
a. ‘ep? triangularis sterni isin a state a. The triangularis sterni is well

re on. developed.
b. No thoracic segment of the external 6. The external oblique extends for-
oblique is present. wards to the first rib.
c. The rectus abdominis ends on the cc. The rectus abdominis extends to the
lower set of ribs. first rib and sternum.

d. Interchondral articulations may be d. No interchondral articulations.
present.
_ @ Seventh costal cartilage attached ¢. The seventh costal cartilages are

to and moves with the meso- attached to and move with the
sternum. xiphi-sternum,

IV. As regards the Diaphragm.

a, The pericardium is adherent to the a. The pericardium is separated from
diaphragm. the diaphragm by the lobus

: : azygos.
b. The spinal segment has a wide origin 0. No eos origin or fibres are
__ from the arcuate ligaments. present.
¢. The upper level of the diaphragm is_ c. The a level of the diaphragm is
+ aig at right angles to nearly parallel to the ventral line
e trunk. of the belly. .

Mr Kerra exhibited the following models: (1) one showing the
manner in which the splenic flexure of the colon was displaced as the
stomach emptied or filled; (2) one showing the respiratory move-
ments of the kidney; (3) three models showing the respiratory
movements of the liver, stomach, and spleen.

(2) The Architecture of Bone illustrated by Réntgen Stereoscopy.
By W. S. Haveuron, Dublin, and A. Francis Dixon, Cardiff.

As has been pointed out by Reiner and others, the architecture of
the various bones of the skeleton can be beautifully demonstrated by

lxii PROCEEDINGS OF THE

stereoscopic radiographs. ‘To obtain good results the specimens made .
use of may be macerated, or merely roughly cleaned. Suitably-
prepared lightly-printed photographic reproductions, when viewed in
the reflecting stereoscope, illustrate very clearly the internal structure
of the bone and the arrangement of the lamelle of its cancellous
tissue. The whole effect is as if one were looking at a semi-transparent
reconstruction of the bone. The method has some advantages over
the ordinary ground sections; for instance, it enables one to follow
with considerable ease the disposition of the lamellae, even when
they are constantly changing their direction, and lie in very different
planes in different parts of their course. Further, it is possible, by
using large photographic plates, to obtain stereoscopic reproductions
of the entire long bones, and also to obtain views illustrating the
disposition of the lamelle in planes at right angles to one another in
the same specimen. As the process is not a tedious one, in a relatively
short time one can become possessed of reproductions illustrating the
structure of the bones of the entire skeleton. The pictures bring out
clearly a system of spirally-arranged lamellze common to all the long
bones as well as the better-known longitudinal and transversely-
arranged ones. In all the long bones some of the lamelle are seen
forming right and left handed intersecting spirals. These are
particularly well marked in the femur and humerus, but are also
present in all other bones of a tubular nature. Where such bones
are bent or curved, the spiral lamelle are more strongly developed,
and they undoubtedly give more rigidity to these parts: In the
ribs the spiral lamelle are well seen, and they are also present in the
transverse processes of the thoracic vertebre and in the ends of the
clavicle. When the lamelle in question are traced towards the
articular ends of the long bones, they are noticed to undergo a change
in direction, and to become perpendicular to the surfaces of pressure
at the joints.

The reproductions of the vertebrae by the stereoscopic method are
very beautiful, as the absence of dense bone renders it easy to obtain
pictures showing, in its minutest detail, the disposition of the lamelle
and the changes in direction which they undergo near the surfaces of
pressure, corresponding to the articular facets. The ‘ pressure’ and
‘tension lamelle’ in the upper end of femur are shown very con-
spicuously.

A model illustrating diagrammatically the arrangement of the
spiral lamelle in the case of the femur was exhibited, and also a
number of bone sections, to show their disposition.

In making the pictures, the apparatus devised by Dr M‘Kenziec-
Davidson of London was utilised.

_ ANATOMICAL SOCIETY OF GREAT BRITAIN AND IRELAND. lxili

J ~ (8) On the Development of the Lower Ends of the Wolfian Ducts and

Ureters and the Adjacent Parts of the Cloaca. By Prof.
A. Rosrnson.

The ureter arises as a bulbous diverticulum from the lower part of

39 the Wolffian duct in embryos from three and a half to four weeks

ce old, which possess a length of about 5-8 mm., and after its appearance

the lower segment of the duct is known as the allantoic segment.

The allantoic segment is common. to both Wolffian duct and ureter,

-and-it opens into a backward prolongation of the genito-urinary

segment of the cloacal chamber, which may, for convenience, be
termed the Wolffian angle. The allantoic segment persists until the
embryo is 14 mm. long and about six weeks old ; then it disappears,
and the Wolffian duct and the ureter open separately into the
genito-urinary chamber. The exact manner in which the two canals

attain their separate apertures and are afterwards moved apart until

the ureter ends in the bladder section of the genito-urinary chamber,
and the Wolffian duct, at a much lower level, into the genito-

eanal, has never been fully elucidated; but it is generally
believed that in the first place the allantoic segment of the
Wolffian duct is absorbed into the genito-urinary chamber, and
that, thereafter, on account of the rapid growth of the wall
of the genito-urinary chamber between the orifices, the latter
are forced apart. ‘This may possibly be the correct explanation, but
the sections of an embryo measuring 14°5 mm. in length, and
presumably about seven weeks old, which has recently been added
to my collection, suggest an alternative view. It should be noted,
however, that I have not found a similar condition either in any other
human embryo or in the embryos of other mammals. Possibly this
particular embryo may be abnormal, but the features it presents are
so distinct that they are worthy of note.

The dorsal and ventral sections of the cloaca are still continuous
with each other, and neither opens on the surface. The ventral
section, or genito-urinary chamber, is flattened dorso-ventrally, and
in transverse section it is somewhat semilunar in outline at its widest
part, which is in the region of the apertures of the Wolffian ducts
and ureters. In this situation the lateral borders of the chamber
are prolonged dorsally, forming what I have termed the Wolffian

The ureter and the Wolffian duct on each side open close together
into the corresponding Wolffian angle of the genito-urinary chamber,
the former immediately to the outer side and slightly in front of the
latter. So far, therefore, the specimen presents nothing which is
opposed to the assumption that the allantoic segment of the Wolffian
duct has been absorbed until the two canals have acquired separate
apertures, but the point which is of importance is that from the
posterior or lower margin of the orifice of the Wolffian duct a
grooved ridge, the Wolffian ledge, runs caudally on the wall of the
genito-urinary chamber, and gradually disappears at the junction of

lxiv PROCEEDINGS OF THE

the Wolffian angle with the body of the chamber. The lateral
margins of the groove are continuous anteriorly with the lateral
margins of the aperture of the Wolffian duct, and apparently they
fuse together to form the lower part of the ventral wall of the duct,
which projects slightly into the cavity of the Wolffian angle of the
chamber. Obviously, if the lateral margins of the groove were to
fuse from before backwards, the aperture of the Wolffian duct would
be carried further backward in the chamber, and its distance from
the opening of the ureter increased. It may be supposed that after
the fusion of the margins of the groove, the lower portion of the

Wolftian Duct.

3 Ureter.
y ~~ Opening of Ureter.
Wolffian Angle of Genito- :

urinary Chamber. Wolffian Ledge.

Genito-urinary
Chamber.

yi, Surface Epithelium.

Reconstruction model of a human embryo 14°5 mm. long showing grooved
ledges running downwards in the posterior wall of the genito-urinary
chamber from the orifices of the Wolffian ducts.

Wolffian canal, which has thus been prolonged further backwards,
separates from the wall of the genito-urinary chamber except at
its lower extremity, and that consequently it enters the wall
of the chamber, after the separation is completed, at a lower level
than the ureter.

It is, of course, quite possible that the ridge and the sulcus are the
remains of the allantoic segment of the Wolffian duct, in which case
the Wolffian angle of the genito-urinary chamber must have been
prolonged dorsally and forwards round the ventral wall of the duct,
which would then project into the dorsal wall of the chamber; and
it may be suggested that when this stage has been attained, the

the duct disappears, producing the condition found
f this is the case, then the separation of the orifices.
the duct must be due entirely to the growth of the

be noted, however, that in the specimen under
1e cavity of the Wolffian angle of the genito-urinary
; forwards, along the ventral wall of the Wolffian
+ distance beyond the point where the ureter and the
the chamber.

Tait eas orga

a) hein J a.)

Bo. aati {xe ey sont:

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SINOING LIST MAY 15 3

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