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Se OF ANATOMY
Pe PHYSIOLOGY

CONDUCTED BY

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ARTHUR THOMSON,

ARTHUR genre

ROYAL COLLEGE OF SURGEONS OF ENGLAND ;

AND

UNIVERSITY OF EDINBURGH.

VOL. |:
THIRD SERIES.—VOLUME XI.

WITH PLATES AND NUMEROUS ILLUSTRATIONS IN TEXT:

LONDON: 3°
CHARLES GRIFFIN AND COMPANY, LTD.,
EXETER STREET, STRAND.
1916,

‘3

PRINTED IN GREAT ‘BRITAIN
NEILL AND CO., LTD.,

\S\

CONTENTS

FIRST PART—OCTOBER 1015.

Pca RY PAGE
‘Homotocies or THE CHELONIAN AND MAMMALIAN Typxs oF GENrTALIA. By Pro-

a Ds a has, Si eplaseec OMe ph i ke gem car ee 1

PMENTAL Gaston IN THE PERICARDIUM, THE MESOCARDIA, AND THE PLEURAL
‘Sacs IN THE Human mensre. By Davip Warterston, M.D. . . °°... 24

Sealy By aces E. Couuince, M.Se., F.LS., et. . . . ‘ 37

‘THE Factors CONCERNED IN CAUSING RoTATION or THE INTESTINE In Man. By
J. Ennest Frazer, F.R.O.S., and R. H. Rossrns, M.D, Cantab. Saber cae 75

SECOND PART—JANUARY 1916.

: EnpocranraL Casts AND Brain Form: A OrrricisM oF some Recent Sprcvna-
tIons. By Professor J. SymineTon, M.D., F.R.S. Cee a, he mn Cee, a

Tur ARTERIES OF THE Pons AND MepuLiA Ostoneata. By J. S. B. Stoprorp, M.D. 131

THe Cosrau Muscu.ature. By Tuomas Watmstey, M.B. SRC toss ey | SR

vi Contents

Tue TRANSITION OF THE CILIATED EPITHELIUM OF THE NOSE INTO THE SQUAMOUS
EPITHELIUM OF THE PHARYNX. By W. Sonier Bryant, A.M., M.D.

HEREDITARY ABNORMAL SEGMENTATION OF THE INDEX AND MIDDLE FINGERS. By
H. Drinkwater, M.D., M.R.C.S. Eng., F.L.S.

THE MEASUREMENT OF DIAPHYSIAL GROWTH IN PROXIMAL AND DisrTAL DIRECTIONS,
By Professor KenELtM H. Dicsy, M.B., F.R.C,S.

THE GENITALIA OF GALEOPITHECUS. By Professor FrEDERIC Woop JonEs, D.Sc.

OBSERVATIONS ON THE POPLITEAL GROOVE ON THE Femur. By Ginperr I.
STRacHAN, M.D.

THIRD PART—APRIL 116.

THE STRUCTURE OF THE BLASTODERM, AND THE CONTINUITY OF THE CELL-ELEMENTS
DURING THE EARLY STAGES OF DEVELOPMENT. By Professor J. CAMERON, M.D.,
D.Sc., and R. J. Guapstonr, M.D., F.R.C.S.

Two ExampLEs oF Carpiac Matrormation. By R. J. Guapsronz, M.D., F.R.C.S.,
and C. H. ReissmaAnn, M.A., M.D., M.R.C.P., B.Sc.

THe THyrorpEA Ima ARTERY. By G. Wyatr Pratt, B.A.
Tue West Scorrisu Skunu. By Professor T. H. Brycr

THE ARTERIES OF THE Pons AND MEpULLA Oxstoneata, Part II. By J. S. B.
Sroprorp, M.D.

In Memoriam: Principal Sir Witt1aAM Turner, K.C.B., F.R.S., etc., 1832-1916

FOURTH PART—JULY 1016.

Sur LA STRUCTURE DU PouMon pu DavupHin (DELPHINUS DELPHIS). By Dr Jost
MARTINS BARBOSA

An UnusvaL Perirongan Sac. By F. A. Hepwortu, M.A., M.B. Camb., F.R.C.8.

PAGE

172

177

187

189

204

207

228

239

241

255

281

THE Pertcarpium. By Martin R. Cuasz, M.D...

HIBIAN ParaspHENorps, By Dr H. LEIGHTON KESTEVEN

; CE OF OVARIAN PERITONEAL SACCULATION IN THE
merann Revecipe, M.D. 66 enw) Peas. oe

In THE Human Supsecr. By Dr James F. GeMMILL and

eis . w- . . ay erate: (ae .

- . . . . . . . . .
.
. . . . . . . . . .

316

324

JOURNAL OF ANATOMY AND
PHYSIOLOGY

* THE HOMOLOGIES OF THE CHELONIAN AND MAMMALIAN
ri ; TYPES OF GENITALIA. By Freperic Woop Jongs, D.Sc.,
es Professor of Anatomy in the University of London. London
School of Medicine for Women.

In a former paper (1) I have endeavoured to record what have appeared to
me to be the eprint features of the copulatory organ as it is seen

pment of this copulatory organ from the simple condition of mere
stional cloacal eversion seen in most Amphibians and in Sphenodon.
Th already expressed my belief in that paper and elsewhere (2), that
th type of Chelonian copulatory organ presents many very striking
resemblances to that seen in the Mammalia.
it These resemblances are not only worthy of record for their own sake,
___ and for the light they may possibly shed on the phylogeny of the Mammals;
__ but since, as I think, they help to explain the real nature of certain features
_ of the external genitalia of man, they are deserving of attention from the
_ human anatomist and the student of medicine. ,
_ The Chelonian copulatory organ consists of an intracloacal genital
tubercle, the genital tubercle being developed on t-?s ventral or pubic
wall of the cloaca; but the repetition of this definition will effect but
little unless, at the outset, we arrive at some definite agreement as {«, the
___ precise meaning of the term “cloaca.” \ pn
___ Cloaca or Cloaca maxima, the Latin name for the great main sewer o.

venient term for the main sewer of animals very early in the history of
_ anatomy, nevertheless it took some time for any very precise definition to
_ become attached to the use of the word.
_ Hieronymus Fabricius ab Aquapendente (1537-1619), from his studies
upon the reproductive system of birds, has left his name indelibly associ-
ated with the mysterious “bursa Fabricii,” the actual nature of which is
still unexplained three centuries after he had probed into its ne

VOL. L. (THIRD SER. VOL. XI.)—OCT. 1915,

ee Rome constructed by Tarquinius Priscus; was naturally applied as a con- — F

2 Professor Frederic Wood Jones

Harvey (1651), who followed the teaching of Fabricius closely in his
work on the Generation of Living Creatures, leaves no doubt as to the
anatomical entity that he describes under the name cloaca.

In the original Latin edition, when describing the visceral outlets of —
the hen, he writes: “Foramina hec omnia adeo sibi invicem vicina sunt,
ut fere in unam cavitatem concurrere videntur; quam (utpote stercori et
urine communem) cloacam licet appellare ” (3).

In the English edition of 1653 George Ent has rendered this passage
as follows:—“ These holes are all so neer neighbours the one to the other,
that they seem all to consent to pass into one and the same cavity ; which
(because it lies common both to the excrement and the urine) may be called —
the sink.” And in another passage in the same work the sink is alluded
to as “the publik cavity ” (4).

Gerardus Blasius (1617-1682) uses the term cloaca in exactly the same.
sense (5); and Samuel Collins in his Systeme of Anatomy (1685) applies
the same word to the same avian chamber (6).

These authors leave no doubt concerning the chamber with which they
are dealing; it is the chamber below the openings of the urogenital and
alimentary tubes into which the contents of both are passed on their way
to the exterior.

It is perhaps best to turn to a modern author and find in his definition
of the term some clue for clearing up the present uncertainty of the
meaning of “cloaca.” Professor W. Felix defines it as follows :—“By
cloaca is understood the part of the posterior intestinal bay that lies caudal
to the point where the allantois is given off” (7). It is quite obvious that
the writer is here using the term cloaca for a chamber very different from
that designated cloaca by the older anatomists.

The difference between these two chambers may be stated briefly.

Professor Felix aliudes to a hypoblastic cavity formed by the continuity
of the ventral allantois and the dorsal gut ; Harvey indicates an epiblastic
eavit- which invaginates the hind end and ultimately becomes continuous
yw’ «he hypoblastic derivatives.
These two cavities are at one time entirely separated from each other
_ by the cloacal membrane, but by the rupture of this membrane they
communicate freely at an early stage of embryonic development. Never-
theless all trace of their original distinction is not lost. “The hypoblastic
section of the cloaca of birds, which receives the openings of the urogenital
ducts, is permanently marked off by a fold from the epiblastic section with
which the bursa Fabricii communicates ” (Balfour, 8). In birds the line of
demarcation is particularly conspicuous, but in representatives of other
Orders it is still distinctly indicated.

Homologies of the Chelonian and Mammalian Types of Genitalia 3

s ___ Since, then, there are two chambers to which modern usage permits the
application of the term cloaca, it has become customary to speak of an
endodermal cloaca and an ectodermal cloaca. It is to be doubted if this
nomenclature is an ideal one, and it has certainly led to a good deal of
confusion. In birds, as we have seen, the two chambers are particularly
distinct, but even professional ornithologists are not very rigid in their
terminology. According to Elliot Coues, “a cavity, originally that of the
allantois of the embryo, persists in common with that of the intestines,
and is the cloaca. The same cavity contains the penis of those birds which
are provided with a copulatory organ” (9). Gadow’s terminology is widely

used by ornithologists. Quoted from Newton (10), Gadow defines the
cloaca as “the dilated terminal portion of the alimentary canal, which
opens through the vent.” The cloaca is subdivided into “a vestibulum, a
_ urogenital or middle, and a rectal or innermost chamber.” It is quite

- obvious that in these definitions both endodermal and ectodermal portions
are included in the chamber termed cloaca: and it is true to say that we
have in common usage to-day the term cloaca applied to either chamber
ae separately or to the two combined. I think that Balfour, of all modern
* authors, has selected his terminology with the best precision. The

endodermal cloaca is his “cloacal section of the alimentary tract which
receives the urogenital ducts”; while the ectodermal cloaca is rightly
synonymous with his “ proctodeum” (11). The student of human anatomy
is apt to forget that the proctodezeum includes all that depressed area which
is separated from the posterior hypoblastic cavities by the proctodeal or
cloacal membrane, as the stomodzeum is separated from the anterior end of
the hypoblastic tube by the stomodzal or oral membrane.

A modified terminology has come into the literature of human embryo-
logy. “The anal membrane is-also at the bottom of an ectodermal
depression which may be regarded as a part of the ectodermal cloaca, but
which is termed the proctodeum or anal pit” (12). This definition is
quoted from the work of Lewis; but it is almost universal among human
embryologists to so limit the use of the term proctodeum to that small
invagination which forms the anus.

The endodermal cloaca in the higher animals is, of course, but a
temporary chamber, for by some means or other the hind gut becomes
separated from the urogenital sinus, and the terminal portions of the
separate chambers approximating the cloacal membrane cause that
membrane to be subdivided into an anterior portion or urogenital membrane
and a posterior portion or anal membrane. If then we are to speak of a
true cloaca in such a form as man, we should denote all that area of the
body which, originally lying at the bottom of a depression, has opening

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4 Professor Frederic Wood Jones

upon it the anus and the urogenital sinus. It will be impossible to define
the limits of this area more precisely without following out its evolution,
both phylogenetic and ontogenetic, and I will therefore reserve a rigid
definition of the human cloaca until this evolution has been followed.

But at any rate I may make a definite rule of terminology that shall
apply to this series of papers; for by “cloaca” I shall signify only the
ectodermal cloaca or primitive proctodeeum, and by intracloacal copulatory
organ I shall signify the developed product of a genital tubercle (phallic
tubercle or cloacal tubercle) which originates in such an ectodermal cloaca.

An intracloacal copulatory organ still persists in the Mammals both
among the Prototheria and among the Eutheria, and many partially
cloacal types occur in more than one Order. ;

In some ways the mammalian intracloacal copulatory organ has made
advances upon the condition seen in the Chelonian reptiles, and it is at
this point, where further development starts, that the first attempt must
be made to homologise the parts of the mammalian and chelonian structures :
provided always that such comparisons seem profitable and natural, and
appear to be real expressions of phylogenetic elaboration.

It is no new or original thing to attempt an interpretation of the —
chelonian features in the mammalian external genitalia. The condition
of the Tortoise has before now been made the stepping-stone towards an
understanding of the genitalia of the Mammals. Professor Keith has
directed considerable attention to this point (13); and since his results are
clearly stated, and his illustrations leave no doubt as to his conclusions,
I will first deal with the homologies as he has defined them. . This account
I criticise since it is the most authoritative and most readily accessible
work to which the student may turn; and I criticise it only as such, for
I am well aware that as a statement of the actual derivation of the parts
of the human genitalia it does not express Keith’s present views, between
which and those that I put forward here there is, I think, no very essential
difference.

Keith has compared the condition found in the Tortoise with that
present in Echidna, and this, without doubt, is the best starting-point for
inquiry. The work of Keibel upon Echidna renders the anatomical features
with which we have to deal particularly accessible, and makes direct
comparisons with other forms possible and profitable.

The Chelonian condition is described by Keith as follows :—“In the
tortoise the penis is intracloacal; it is formed by a modification of the
ventral or pubic wall of the cloaca. Practically only the glans is free;
this is cleft and forms a groove; when erect the margins of the groove
approximate and form a canal.” Echidna is thus described: “The penis is

Homologies of the Chelonian and Mammalian Types of Genitalia 5

yul-intracicacel, but the lips of the glans have fused and formed what
may be named the phallic canal.”
_ The conclusions are clearly put and may be quoted as a whole. “The
seminal canal is thus made up of two parts: (1) the urogenital sinus
derived from the endodermal cloaca ; (2) of the phallic cana] made by the
“union of the lips of the phallic groove.” And again, “In man the penis is
_ permanently extracloacal. The urethra is made by the union of the
a ic canal and urogenital sinus, but the first element is greatly reduced
in extent, forming merely that part of the urethra contained in the glans.”
It is obvions at the outset that this comparison has many attractions
and can be supported by several independent observations upon normal
Se looment, and by the study of human anomalies. Keith’s explanation
leaves but little unsatisfied, but it seems to me that it starts from a wrong
“interpretation of the Chelonian copulatory organ. In another passage he
alludes to this structure as “a phallus or glans”; but I think it is very
much more than that, for it contains all those elements which compose the
whole of the mammalian penis. More than this, what Keith names the
of ic groove” is obviously the same depression which, following Owen,
I have termed “seminal groove,” and this groove involves the whole body
_ of the copulatory organ right back to the opening of the urogenital sinus.
_ The complete closure of the phallic or seminal groove, therefore, to my
_ mind, creates the whole of the penile urethra and not that portion of the
_ canal which is within the glans. The urethra which is within the glans is
in every way peculiar, but I do not see in its development anything to
suggest that it has been formed by the folding over and the meeting of
lateral margins: its separate and special development is certain, but it is
effected in that terminal portion of the copulatory organ which is distal to
the last traces of the seminal grodve. The glans is free of seminal groove
and seminal guides, and with the closure of the seminal canal in the body
of the penis this terminal solid portion is tunnelled (as was described first
by Berry Hart and afterwards independently by myself), by an ingrowth
which hollows out the fossa navicularis and is at times marked off form
the seminal groove portion by the valve of Guérin.
Having made the Chelonian seminal canal represent only that portion
of the urethra which lies within the substance of the glans of the Mammal,
Keith derives the penile urethra from the urogenital sinus. This term
- again needs definition, The urogenital sinus is a derivative of the
endodermal cloaca; being that ventral portion of the endodermal cloaca
left after the rectum has become separated as the dorsal portion. It
consists of a chamber into which both genital and urinary channels open
in the embryo, and which is separated for a time from the ectodermal

6 Professor Frederic Wood Jones

cloaca by that portion of the cloacal membrane termed urogenital membrane.
The after-history of the urogenital sinus becomes complicated in the
Mammalia, and I will return to this subject. In some Mammals it is a
long canal in both sexes, but in none does it take any share in forming
any portion of the penile urethra, which is derived from structures within
the true ectodermal cloaca. In Man there is no urogenital sinus, in the
strict sense of the term, in the female; but in the male it is represented
by that portion of the urethra which is limited above by the opening of
the genital ducts, and below by the anterior layer of the triangular
ligament or fascia of origin of the penile musculature. It is true that
the male penile urethra forms a common urinary and genital passage, but
this is not to be taken, in any sense, as being an index of its derivation
from the urogenital sinus.

So much I have set out by way of explanation, for, although I am
aware that the statements I have quoted do not represent Professor Keith’s
present views as to the ontogeny of the human urethra, they are apt to be
taken by those in search for the phylogeny of these structures as representing
the homologies of the chelonian and mammalian copulatory organs.

In order to follow out the homologies more completely, I propose to
establish comparisons between a typical Chelonian and four Mammalian
types—(a) Echidna, (b) certain Shrews, (c) Man, and (d) the Mole (Talpa
ewroped). The Chelonian characters (see fig. 1) I have already discussed
in a previous paper (14).

(a) The condition of Echidna I shall be forced to take from the work
of Keibel and from other published accounts, for I have had no opportunity
of making a first-hand examination for myself. I am unable to follow
the developmental phases in the Monotreme for lack of recorded observa-
tions, and it will be necessary to turn at once to the adult condition.
Briefly, the copulatory organ of Echidna may be described as an intra-
cloacal structure which has made advance upon the Chelonian condition
in that instead of a mere seminal groove it possesses an incomplete seminal
canal. Owen has summed up the Monotreme condition by saying that
“if the canal of the penis were slit open along its under part, and thus
converted into a groove, the male organs of Ornithorhynchus would be
like those of a Tortoise” (15). In the Chelonian, the completed seminal
canal exists only during erection and extrusion, in the Monotreme it
exists in the quiescent state over the great part of its extent, but is
complete only during erection and extrusion. The seminal guides of the
Chelonian meet only during functional activity; in Echidna they have
met and become fused in the mid line and so completed a permanent
seminal canal, save only over a brief interval intervening between the

Homologies of the Chelonian and Mammalian Types of Genitalia 7

orifi € urogenital sinus and the basal portion of the penile canal
(see fig. 2). In both cases the same functional end is secured; the
urogenital sinus discharges its products into the cloaca at all ordinary
times, but during sexual activity they are carried along the seminal canal
to the tip of the copulatory organ. The condition of the Monotreme is

Bladder.

. Cloacal opening
of rectum.

Genital tubercle .~ i

8 Professor Frederic Wood Jones

type. The glans of the Monotremes is complex and bifid, each distal
portion being tunnelled by a separate channel. The prepuce is highly
developed, and is a permanent structure enveloping the terminal portion
of the copulatory organ. In the female the copulatory organ is greatly

Fig. 2.—The cloaca and copulatory organ of Echidna. (After Keibel.)

reduced, the clitoris being a small flattened body showing a distal tendency
to subdivision. The seminal guides are, of course, unfused in the female
and do not appear to be at all conspicuous, for I am unable to find any
account of their state of development.

(b) In certain shrews a cloaca as perfect as that of the Chelonian or
the Monotreme still persists; the copulatory organ remains intracloaeal,

q
i x

Homologies of the Chelonian and Mammalian Types of Genitalia 9

_ but it-shows ‘some further advances upon the Monotreme condition. As

an example of this stage of development I shall describe and figure the
copulatory organ of Crocidura bottigi, although members of several other
sub-families and genera of the family Soricide exhibit a similar condition.
Here the cloacal outlet is a conspicuous orifice, elongated in its antero-
posterior diameter and surrounded by a prominent margin which gives

rise to a sparse growth of certain specialised hairs (see fig. 3). Within

the cloaca, and in a special recess of its ventral or anterior portion, lies
the copulatory organ.
Compared with Chelonians and Monotremes, the greatest advance

Fic. 3.—External view of the cloacal outlet of a male Crocidura bottigi.

consists in the perfect and permanent formation of the seminal canal by
the complete fusion, in the whole of their length, of the seminal guides
of the male. Although ip these shrews the copulatory organ is still an
intracloacal one, and so shows a very lowly linkage with Monotremes and
Chelonians, there is initiated at this stage that great mammalian change
by which all the products of the urogenital sinus are at all times passed
through the male seminal canal. These shrews are therefore in a most

interesting intermediate condition: they possess a true cloaca, and an

intracloacal copulatory organ serving not only for copulation and insemina-
tion, but also as the terminal] duct of the urinary system (see fig. 4).

All this great alteration of functional adaptation is brought about by
the complete closure of the seminal guides over the entire length of the
male seminal groove.

Other modifications are of a minor and secondary nature. The penis

10 Professor Frederic Wood Jones

becomes considerably elongated (and in some types coiled); the terminal
portion of the organ is not bifid, and the whole structure becomes more
typical of the penis seen in the rest of the Eutherian Mammals. In the
female the seminal guides remain ununited, and a clitoris is present which
is in every way remarkably similar to that of the female Chelonian.
These ununited seminal guides constitute the labia minora of mammalian

| (a
fF
f “Y®

i

j

Fic. 4.—Section of the cloaca of a male Crocidwra bottigi.
P, penis ; C, cloaca; R, rectum.

terminology, and they exist as well-marked folds running along the dorsal
aspect of the clitoris, fading away proximally near to the orifice of the
urogenital sinus.

It is to be noted in connexion with these cloacal shrews that although
in the complete closure of the seminal canal in the male they have
progressed further from the Chelonian type than have the Monotremes,
still in some other features of the copulatory organ they retain much
more the simplicity of the Chelonian. To this point I will return again
when dealing with the genitalia of the Insectivora as a group.

Of the embryonic development of the cloaca and intracioacal genital

Homologies of the Chelonian and Mammalian Types of Genitalia 11
_ tubercle in these animals I am ignorant; the reproductive habits of the

smaller cloacal shrews are quite unknown, and material upon which an
embryological investigation could be carried out seems particularly difficult
to obtain.

_ (ce) In Man we have in the early stages a very complete recapitulation
of the Chelonian type. In such embryos as the 3-mm. (E. B.) embryo of His,
the rudiments of the copulatory organ appear as nearly approximated

Fic. 5.—Condition of the cloaca and rudiments of the copulatory organ of an early
human embryo. (Partly after Keibel and partly from an embryo of 12 somites.)

bilateral elevations upon the ventral wall of a shallow cloaca (see fig. 5).
These elevations extend from the cloacal membrane to the anterior cloacal
margin which is situated not far caudad of the umbilicus. It is therefore
obvious in Man, as in the Chelonian, that this copulatory organ 1s an
ectodermal organ and is developed in the ectodermal cloaca or proctodeum
proper. Fortunately in Man there is abundant material in which to follow
out the phases of development of this rudiment of the copulatory organ,
and considerable certainty may be felt as to the actual condition at
different stages.

The next phase of development is associated with the separation of
rectal and urogenital passages, with the consequent demarcation of an

12 Professor Frederic Wood Jones

anterior and a posterior part of the cloaca and the cloacal membrane.
That portion of the cloacal membrane against which the proximal portions
of the genital eminences abut is now known as the urogenital membrane,
and by the rupture of this membrane the urogenital sinus comes to open
between the bilateral rudiments of the copulatory organ.

Fic. 6.—Diagrammatic drawing of the human external genitalia to show
the anatomical structures mentioned in the text,

Meanwhile the rudiments of the copulatory organ are becoming more
developed and more specialised. The two bilateral elevations seen in the
embryo of 3 mm. have become fused at their distal ends into a single
body, but the evidence of the bilateral origin and median fusion is plainly
seen in the presence upon its dorsal surface of a median groove (see fig. 6).

This groove is a mere linear depression towards the distal extremity
of the genital tubercle, but it broadens out at its base, for in the basal
portion of the groove is included the whole width of the urogenital

Homologies of the Chelonian and Mammalian Types of Genitalia 13

-membrane-—More than this, the bilateral rudiments of the copulatory
organ extend even behind the urogenital membrane and on to the bridge
of tissue which separates this membrane from the anal membrane. At
the tip of the genital tubercle the groove disappears, and it does not invade
the terminal rounded boss which is beginning to be evident upon the
developing tubercle. This dorsal groove is the homologue of the seminal
groove of the Chelonian, and its disposition upon the embryonic human
copulatory organ is identical with that seen in the adult Chelonian.

Next, upon the margins of this groove the seminal guides become
developed.. Meanwhile the copulatory organ has enlarged and become
protruded from the anterior portion of the cloaca: for the functional
eversion of the Chelonians, Monotremes and cloacal shrews becomes an
ordinary developmental phase in the higher Mammals. The margins of
the cloaca, which run as prominent rounded lips around the whole of the
cloacal orifice, and therefore embrace the anus, undergo some changes with
these developments. With the protrusion of the copulatory organ, the
anterior portion of the cloacal lip becomes pushed forward as a fold
embracing the ventral aspect of the liberated genital tubercle. At the
sides of the genital tubercle the cloacal lips become especially prominent,
_ whilst further back at the sides of the anal membrane, and behind it, they
become less conspicuous. The margins of the cloacal orifice of the Chelonian
are directly represented in these human cloacal lips; but the homology
has been lost sight of in the unequal development which these lips undergo
in Man, and the especial prominence of a portion of them as the labio-
scrotal, or outer genital, folds has rather obscured the interpretation of
their true significance. With the eversion of the copulatory organ in Man
the whole cloaca becomes shallowed and ultimately forms part of the
general body surface, and we are at-liberty now to define the limits of this
cloacal area. Originally in the 3-mm. embryo the cloaca and the cloacal
membrane stretched from near the caudal margin of the body stalk
backwards to the base of the tail region; but as the subsequent growth
_ proceeds, the portion of the body wall intervening between the caudal
aspect of the body stalk and the cephalic margin of the cloaca increases in
length, and the umbilicus and the cloaca move apart. This growth is
continued as the whole embryonic body elongates, and its progress is
readily appreciated by studying a series of embryos at different stages.
In the adult, the cephalic margin of the cloaca is marked by that swelling
in the region of the pubic symphysis which constitutes the Mons Veneris
of the female, and the Mons Jovis of the male. This anterior margin of
the cloaca is commonly marked off from the general surface of the
abdominal skin by a depressed line, very evident in female children but

14 Professor Frederic Wood Jones

not so well marked in the male. This line has been named the “line of
Venus,” or by French anatomists “sillon pubo-hypogastrique. ’

The lateral margins of the cloaca are easily followed in the female as
the labia majora, or in the male, over a certain part of their extent, as the
scrotal areas. Behind this the cloacal margin diminishes in prominence
and, after running past the anal orifice, becomes lost by merging in the
general skin surface. The caudal limit of the cloacal margin is not marked
by any definite prominence or fold in man; but the site of its disappearance
is between the posterior margin of the anus and the tip of the cocceyx.
It is on the symphysis pubis anteriorly, and behind the anal orifice
posteriorly, that the lateral portions of the cloacal margins meet; that is
to say, there is no real bond uniting the labia majora ina posterior
commissure between the anus and the vulval orifice. This point I have
‘dealt with in a previous paper, and I will not recapitulate the evidence
derived from adult anatomy here (16).

We may therefore define the limits of the cloacal area in the adult as
all that “perineal” space bounded in front by the Mons, at the sides by
the labio-scrotal folds, and behind by a line passing between the anus and
the coccyx. Embraced within this area are all the contents of the
proctodeum: the genital tubercle with its seminal groove and seminal
guides, the orifice of the urogenital sinus, the bridge of tissue separating
this orifice from the anus, and the anus itself.

These structures are at first. very similar in the two sexes, but very
early some differentiation is apparent, and long before the third month
the male has become very different from the less specialised female.
With regard to the genital tubercle and the structures associated with it,
sexual differentiation is naturally most marked. In the male the whole
organ elongates, the seminal groove deepens and the seminal guides become
prominent. The most important sexual distinction concerns the area over
which the seminal guides extend, rather than the degree of prominence of
their free margins. In the male these folds, which start from near the
free termination of the genital tubercle, run upon either side of the seminal
groove to the orifice of the urogenital sinus, and past this to the anterior
margin of the anus into which (as in the male Chelonian) they enter. It
must not be forgotten that these seminal guides are functionating male
sexual structures, and that they cover exactly the same proctodzal area in
the human male as they do in the male Chelonian. In the human female
embryo, just as in the female Chelonian, they are reduced, not only in
prominence, but also in the proctodeal area over which they extend.
Skirting the seminal groove, they terminate upon the distal portion of the
female genital tubercle exactly as they do in the male; but traced back-

_ Homologies of the Chelonian and Mammalian Types of Genitalia 15

wards, they diminish rapidly in prominence as they pass the orifice of the
<< urogenital sinus, and they are lost some way before the anterior margin of
the anus is reached. The whole evolution of the two sexual types is now

a

Fic. 7.—Three stages in the development of the human male external genitalia.

_ centred in (i.) the comparative growth of the genital tubercle, and (ii.) the
_ fate of the seminal guides (see figs. 7 and 8).

In the male the genital tubercle continues to dengan and the seminal

guides close together and become fused in the middle line over the whole

Fic. 8.—Three stages in the development of the human female external genitalia.

of their extent, thus producing a penile seminal canal marked by a median
_ raphé which runs the whole length of the “perineum” between the scrotal
areas and disappears into the anterior margin of the anus. The actual
erectile masses of the two seminal guides, of course, form the two component
halves of the corpus spongiosum. The erectile tissue ceases immediately
in front of the anal margin as the terminal portion of the “bulb,” but the

16 Professor Frederic Wood Jones

free edge of the seminal guides proceeds further back, and so the median
raphé passes into the anal margin.

In the female, the genital tubercle enlarges but little and the rudi-
mentary seminal guides do not meet or fuse in any portion of their extent.
There is produced in this way a small clitoris, marked upon its dorsal
surface by a rudimentary seminal groove, and with rudimentary seminal
guides depending, as labia minora, free from its margins. The labia
minora of the female being mere rudiments of male functional structures _
are naturally somewhat variable in their development, and this variation
is shown not only in their prominence but in their extent, for they may
fall short and disappear about half way along the vulval orifice, or extend
further back, in some cases possibly continuing behind this orifice and
assisting in the formation of that very vague structure—the “ fourchette ”

The actual erectile masses of the two seminal guides are also reduced,
and form the so-called “bulbs of the vestibule” which, like the free
margins of the labia minora, are somewhat variable in the extent of their
development. Even if the free margins of the seminal guides of the
female pass to the hinder margin of the vaginal orifice and form a genuine
fourchette in some cases, they certainly do not pass further back, and there
is no true raphé on the female perineum, nor is there in the anal margin
ary representation of the sexual seminal guides. It is not a little strange
that there is thus a real sexual distinction between the anus of the male
and female, and I do not know that the fact has been previously noted
(see fig. 9).

The prepuce in both sexes is a secondary formation derived from the
ectodermal covering of the genital tubercle.

I have dealt in other papers with special details of the development
of the external genitalia, and I will not proceed further with these points,
since the description given here is sufficient to permit of a general summing
up of the cloacal evolution in Man.

The cloaca unfolds during development; the genital tubercle is freely
exposed upon the surface of the bedy; and the bridge of tissue interposed
between the urogenital sinus orifice and the anus, which constitutes
the roof or innermost recess of the cloaca, becomes superficial. This
cloacal roof, by being extruded and flattened upon the surface of the
body, forms the “ perineum,’—marked by the fused posterior ends of the
seminal guides in the male but free of these ridges in the female.

The unfolding of the cloaca is not so complete in the female as it is in
the male, and the vulva may be regarded as the ventral segment of a shallow —
cloaca, the posterior segment of which is thrown into continuity with
the general body surface by the fading away of the posterior cloacal

Homologies of the Chelonian and Mammalian Types of Genitalia 17

_ margin. Since here the whole trend of cloacal evolution consists in an
outfolding of the cloacal margins with the eversion of the cloaca, I have
ventured to apply the term Cloaca explicata to animals following this
type of development.

(d) I have chosen the Mole (Talpa europea) as an example of yet
another type of development of the external genitalia, and I have made
this choice mainly because, owing to the kindness of Mr R. H. Burne,
Mr Lionel E. Adams, and Professor L. Doncaster, I have been able to avail
myself of a very complete series of embryos. Further, I have already

Fic. 9.—The actual distribution of the raphé in a male foetus.

described the development of the genitalia in this animal in connexion
with its sexual peculiarities (17), and therefore minutiz need not be entered
into here. I am well aware that, in some ways, the choice of this animal
is a bad one, since the development of the genitalia of the Mole exhibits
some very curious features which, so far as I know, are peculiar to it,
and possibly to its immediate kindred. Still, even if it carries this second
mode of development to extremes, it shows its normal stages particularly
well, and where it departs from the normal method of its type it can be
supplemented from stages seen in other animals of which I am unable
to study so complete an embryonic series. In its earliest stages the Mole
shows exactly the condition described as typical of the adult Chelonian,
or of the early embryo of Man. The cloaca and its margins, and the
genital tubercle, are similar in every way to the same structures in the

VOL. L. (THIRD SER. VOL. XI.)—OCT. 1915. 2

Professor Frederic Wood Jones

18

‘OyITB soxes WOT

“uur 79 pus ‘7z ‘gy ‘6 jo sodmquig
(wadou.na wd) ejoW oYy4 Jo eITVPWUEs [eUIE}xXe 04 Jo GueUIdO[eAsp oY4 UI SedRys INOJ— "OT “OIA

fe) q

Vv

ae Homologies of the Chelonian and Mammalian Types of Genitalia 19

arly human embryo. The primitively intracloacal genital tubercle pro-
ides from the cloaca in the manner I have already described; but now,

and they meet in the middle line, first immediately in front of the anus,
___ and then, the meeting spreading forwards, they begin to ensheath the

Ena es trameemegebin te

pean ensreneteer
fe

genital tubercle itself. The cloacal margins remain prominent around
the anus, they meet and fuse and become prominent in front of it, and
then they embrace the genital tubercle. This wave of union spre
forwards as development proceeds, and when the embryo is abo
way to full term but little of the tip of the genital tubercle is
projecting free of the ensheathing cloacal margins. By f
whole genital tubercle is entirely covered, and the two 4
identical outward appearances (see fig. 10). This grow ; -

20 Professor Frederic Wood Jones

margins prevents the changes which are taking place in the genital
tubercle from being visible to external examination. In the male, however,
exactly the same changes are going on as have been described in the
type Cloaca explicata. The seminal guides have met and enclosed a

Fic. 12.—Section of the terminal portion of the penis
ofa horse. (From Sisson.)

perfect penile seminal canal which is itself enclosed within the ensheathing
envelope of the cloacal margins.

This mode of development of the male external genitalia of the Mole is
typical of a large class of Mammals, and it varies only from that seen in

\ Fic. 13.—The external genitalia of a foetal rabbit. The actual specimen
was a female, but both sexes are alike externally at this stage.

"% 9 * e Mole is somewhat Sat a) and it is riok carried foracunk
mear the region of the umbilicus, whereas in the foetal Sheep

Homologies of the Chelonian and Mammalian Types of Genitalia 21

extremity of the penis approximates the caudal aspect of the umbilicus
(see fig. 11). This variation, which shows all intermediate stages, is one of
degree only, and does not in any way affect the main features of this mode
of development.

It is obvious that the genital tubercle or penis in the adult males of
animals of this type is enclosed within a secondary covering derived from

Fic. 14,—The external genitalia of a foetal mare.

the cloacal margins or outer genital folds; this secondary coveril
to be confused with the prepuce such as we see it in Mangy
nomenclature of veterinary anatomy this secondary covering — oe
the “sheath,” and within this sheath a true prepuce may ory ;
developed for the protection of the glans (see fig. 12).

It is with regard to the female that the mole shows i its
and carries this mode of development to extremes, for the
of the female meet and fuse just as they do in the male,
quite an exceptional departure.

22 Professor Frederic Wood Jones

In the females of other animals following this type of development the
seminal guides remain apart and ununited as they do in the human female.
Again, as in the male, the degree of burying of the genital tubercle varies
greatly ; in the Mole it is complete and the female resembles the male in
all outward respects; in most Rodents the female equivalent of the sheath
is well developed and it is very difficult to distinguish the sexes (see fig. 13);
in the Ungulates its development is not as a rule so great and sexual
distinction is well marked (see fig. 14). This female development of the

Fic. 15,—The vagina and vulva of a young sow
exposed from the dorsal aspect.

V, vagina ; H, hymen; U, orifice of urethra ;
LM, labia minora ; C, clitoris.

h is of course merely a development of the labia majora, and whatever
pree of prominence it is always sufficient to cause the clitoris and its

rifice marked by the hymen is situated at the bottom of a
e fig. 15). The bridge of tissue between the anal margin
ifice is not merely the cloacal roof, but corresponds to the
ior commissure” of human anatomy, — the posterior
floacal margins or labio-scrotal folds.

Homologies of the Chelonian and Mammalian Types of Genitalia 23

___ The whole trend of development in both males and females of this type

_ may therefore be summed up by saying that the cloaca evolves mainly by
the infolding of its margins, and I have ventured to apply the term
Cloaca implicata to those animals which conform to this type of develop-
ment. The factors which underlie the development of these types, and the
extent to which individuals of the various Mammalian Orders conform to
them, I will deal with in future papers.

[Towards the cost of some of the material used in this work assistance
has been afforded from the Dixon Fund of the University of London. |

LITERATURE,

(1) “The Chelonian Type of Genitalia,” Jour. Anat. and Phys., vol. xlix. p. 393.
(2) “The Morphology of the External Genitalia of the Mammals,” Lancet,
11th and 18th April 1914.
(3) Exercitationes de Generatione Animalium : collected works, 1651.
(4) English edition of (3), 1653, p. 19.
(5) Observata anatomica practica in homine brutisque variis, 1674.
(6) A Systeme of Anatomy, 1685, p. 358.
(7) Kerpen and Maui, Manual of Human Embryology, vol. ii. p. 869.
(8) Comparative Embryology, vol. ii. p. 323.
(9) Key to North American Birds, p. 214.
(10) A Dictionary of Birds, p. 90.
(11) Baxrour, Joe. cit. (8).
(12) Kerpen and Matt, op. cit. (7), p. 323.
(13) “The Malformations of the Hind End of the Body,” Brit. Med. Jour.,
Dec, 1908.
(14) Op. eit. (1).
(15) Comparative Anatomy and Physiology of the Vertebrates, vol. iii, p. 644.
(16) “Some Points in the Nomenclature of the External Genitalia of
Female,” Jour. Anat. and Phys., vol. xlvii. p. 73.
(17) “Some Phases in the Reproductive History of the Mole,” Proce. Zoe
1914, p. 191.

DEVELOPMENTAL CHANGES IN THE PERICARDIUM, THE
MESOCARDIA, AND THE PLEURAL SACS IN THE HUMAN
EMBRYO. By Davip Warterston, M.D., University of St
Andrews.

THE descriptions and the figures in this communication have been taken
from wax-plate reconstructions which I have prepared from the following
embryos :—(1) Embryo 2W1, approximately 3 mm. in length: (2) Embryo
S1, 6 mm. in length; (3) Embryo $3, 22 mm. in length.

Fic, 1.—Dorsal wall of pericardial cavity of 3-mm. embryo.
A, right duct of Cuvier; B, sinus venosus; C, body-wall; D, floor of peri-

cardium (septum transversum) ; E, left duct of Cuvier; F, left portion
of atrium ; G, dorsal mesocardium.

f{ these embryos was described in the October number of
The other embryos have not yet been described, and for
ad only say that they were both obtained from operation

cases n excellent condition.
The d models, which included the heart and adjacent portion
of the tr dissected so as to give corresponding views in the various

Developmental Changes in Pericardium, Mesocardia, and Pleure 25

heart-was removed from that cavity by the division of the great vessels
and of the mesocardia, and at a later stage, in the two earlier specimens, the
septum transversum was removed in a piece by making a vertical cut
through the lateral body-wall dorsal to the attachment of the septum so
as to give a view of the thoracic and upper abdominal portions of the
dorsal wall of the body cavity.

The first figure shows the appearances found in the model of the
3-mm. embryo after the removal of the heart from the pericardial cavity.

The dorsal mesocardium forms at this stage a continuous fold lying
vertically and extending from the truncus arteriosus (just above the upper
margin in the figure) to the cephalic (dorsal) margin of the septum
transversum below. The two layers forming the mesocardium spread
out dorsally on to the ridge formed by the mesoderm surrounding the
trachea, and caudally on to the margin of the septum transversum. Two
pulmonary veins lay in this mesocardium, but are not shown in the figure.
The margins of the septum transversum passed laterally to the body-wall
and there received the duct of Cuvier on each side. The mesocardium
at this stage resembles an inverted T, the stem of the T being the dorsal
mesocardium and the transverse piece corresponding to the lateral portions
of the margin of the septum transversum. The vitelline and umbilical
veins opened into the portion of the sinus venosus which is still embedded
in the septum transversum.

The second figure shows the corresponding parts in the embryo 6 mm,
in length. The vertical portion of the dorsal mesocardium has almost
entirely disappeared, only a small portion persisting at the cranial end,
transmitting the truncus arteriosus to the dorsal wall. The disappearance
of the central portion of the dorsal mesocardium gives origin to tk
transverse sinus of the pericardium.

The ducts of Cuvier now pass to the heart from the dorsal ang
from the lateral wall of the trunk, and the left duct opens at a
level than does the right, in contrast to the condition in the first sx
The vena cava inferior opens into the heart through a prolongatj
mesocardial “bare area” on to the floor of the pericardium ve
dorsal edge of the septum transversum. :

The attachment of the lower “venous” portion of theg
cardium now forms a U-shaped figure, one duct of Cu
the extremity of each of the limbs of the U, and th
corresponds to the dorsal margin of the septum transve

The mesial portion of this septum retains its a
body-wall, but laterally—eg. dorsal to the level i
figure—it is not so attached, and at this point

26 Dr David Waterston

can be passed dorsal to the edge of the septum transversum caudally into
the abdominal division of the ccelom, traversing the pericardio-peritoneal
passage.

The ducts of Cuvier have, as it were, been drawn towards the head
from the septum transversum, and the letter F in the figure indicates a
prolongation of the thin margin of the septum, which is continued to the
duct of Cuvier and which is most distinct on the left side. The pleuro-
pericardial passage lies on each side between this fold and the ridge form-
ing the dorsal wall of the pericardium.

The fold F, originally the dorsal margin of the septum transversum,
has, however, undergone a considerable modification, and is now continued

Fie. 2.—Dorsal wall and floor of pericardial cavity of 6-mm. embryo.

A, right duct of Cuvier; B, mesocardium ; C, dorsal margin of septum transversum; D, upper
remains of dorsal mesocardium; E, left duct of Cuvier; F, mesocardial fold.

_ prominent fold on the caudal surface of the septum transversum
extends in a ventral direction to the liver, which now projects from
al surface of the septum, forming the ventral pillar of the
p, and dorsally to the cephalic end of the Wolffian body—a fold
the dorsal and ventral pillars of the diaphragm.

ows the pericardial sac in the third embryo, in which the
sac is Bly closed.

Sof the cephalic portion of the original dorsal mesocardium
mg the aorta and the pulmonary artery to the dorsal wall

as no longer the U-shaped appearance of the second

the U have become shortened by the approximation
by,

9 F

Developmental Changes in Pericardium, Mesocardia, and Pleure 27

‘of the ducts of “Cuvier, and the base of the former U has drawn away from
the orifice of the vena cava inferior. There is now a wide mesocardium
showing: (1) the orifice of the vena cava inferior caudally ; (2) immediately
_ cephalic to this point the mesocardium is widened transversely for the
pulmonary veins of the two sides which are drawing apart ; and (3) cephalic
to these is a narrower vertical portion which bifurcates at the top to
receive at each lateral extremity the duct of Cuvier.

Fie. 3.—Dorsal wall and floor of pericardial sac of 22-mm. embryo.

A, right duct of Cuvier ; B, ascending aorta; C, dorsal arterial mesocardium ; D, arterial
mesocardium ; E, left duct of vier, divided ; F, mesocardial fold; re vena cava |
inferior; H, tioor of pericardium ; K, pulmonary ‘veins ; L, pleura and’ pericardial s
wall; M, apex of lung; N, pleural ‘cavity : P, pulmonary artery, 4,

The left lateral prolongation forms the ligamentum ven cay
of the adult, while the remaining portion of the mesocardium
definite adult venous mesocardium.

The pleuro-pericardial orifice was situated dorso-medi
indicated by the letter F in this figure and in fig. 2. T
closed, and it is clear that the closure has been effec
the fold F with the dorsal wall of the pericardiu
extending from the duct of Cuvier to the point a
portion of the septum transversum is attached to that

28 Dr David Waterston

The changes thus indicated are more readily followed by reference to
figs. 4 and 5, of which fig. 4 shows the portion of the dorsal wall of the
coelomic cavity of embryo | as seen after removal of the septum transversum
by the dissection described earlier in this paper. The upper portion of the
stippled area in that figure (4) indicates the attachment of the dorsal
mesocardium, and the lower part the dorsal attachment of the ventral
mesentery of the stomach. The level of the pointers B indicates the level
at which lay the dorsal margin of the septum transversum and the cephalic

Fic, 4.—Dorsal wall of the pericardial and upper peritoneal portions of
ccelom with pericardio-peritoneal passages and commencing lung buds.

A, ducts of Cuvier in body-wall; B, mesodermal lung swellings ;
C, D, pneumato-enteric recesses ; E, dorsal mesocardium.

iy of the pericardio-peritoneal passage, and in these passages on
; the prominence formed by the mesodermal lung.

shows the corresponding parts in the second embryo. In the
sf the dorsal wall are shown: (1) the upper remains of the

edium, (2) below that the region of the transverse sinus of

the left sideqame fal portion of the fold F, from which a fold is continued
dorsally aroufid the lateral surface of the prominence of the lung.

|

Pes eS Ne

Developmental Changes in Pericardium, Mesocardia, and Pleure 29

The thickened margin of the fold F, forms the pleuro-pericardial
membrane, and the fold prolonged from F on the dorsal of the
septum transversum forms the pleuro-peritoneal membrane, * folds «
_ membranes which effect the closure of the pericardial sac an
of the pleural from the peritoneal divisions of the ecelom ave pre
have not as yet united to the walls opposed to them so ‘as to effect that
closure. Comparison of figs. 3 and 5 shows the great growth changes
which occur, and which alter profoundly the relative positions of the lungs
and pleural sacs to the pericardial cavity. |

a a >
ao |
Fo toe D
B ee
Ls E
F
x G
K
N L
M
a
_ Fic. 5.—Dorsal wall of pericardial sac, pericardio-peritoue pges, and upper
: part of peritoneal ccelom in 6-mm, emi:
we.
A, duct of Cuvier; B, mesocardial fold; D, dorsal mesocardium, fal ; E, duct of Cuvier; F,
mesocardial fold, now forming pleuro-pericardial and oval matgi. ™f pleuro-peritoneal mem-

brane; G, ventral mesogastrium ; H, lung bud in pleural division ~~\ecele
and left pneumato-enteric recesses, the left very small; M, stomach; i ¥

In fig. 5 the developing lungs lie dorsal and caudal to the ie
and on the caudal and dorsal aspect of the original septum transv4®
- Fig. 3 shows that the lung has grown towards the head beht
upper part of the pericardium, and has also extended ventrally so
intervene between the pericardium and the lateral body-wall. With
growing lung, the pleural cavity has expanded in the loose mesenchym@s
tissue which occupied these regions. The illustrations forming figs. 3 and Wy
5 were made by Mr W. Champneys, and the models of embryos 1 and
2 have been reproduced very successfully by Mr S. Boyes, 68 Hafton
Road, Catford, S.E., who is prepared to supply copies of these models.

Part of the expense of the preparation of the original wax-plate
models was defrayed by a grant from the Royal Society.

THE MUCINOUS CHANGES OF THE VAGINAL EPITHELIUM
OF CERTAIN MAMMALS IN PREGNANCY.' By F. J. F.

BARRINGTON.

(From the Graham Research Laboratories, University College Hospital Medical School.)

THE tissues of freshly killed animals were hardened in a sublimate-formol-
acetic mixture and cut in paraffin. Mallory’s iron hematoxylin, van Gieson
and Mayer’s muci-carmine, were the stains used. The latter was the only
mucin reagent employed.

GUINEA-PIG.

In Pregnancy and Ltctation.—Only such animals were considered
pregnant as showed visible swellings in one or both uteri. It therefore
follows that the very earliest stages of pregnancy were not observed in
this series, since the utertue swelling takes some time to develop. The
period of pregnancy was not known in any case; it was estimated roughly
by the size-of the foetus Eighteen animals were examined, which were
classed as five eal pregnancies, six about mid-term, and seven late
pregnancies. Of the hist, two appeared to be about full-term. Consider-
ing first the five earl’ cases, the vaginal epithelium of one consisted of
two or three laye~: of cells with large, clearly staining nuclei. The cells
next the lume. were shortly columnar with the nucleus situated at the
“1, while the part of the cell on the luminal side of the nucleus
ir mucin reaction. The epithelium of the next two cases resembled
first, except that the cells next the lumen were taller and the mucin
action was more marked. The mucin was still only situated on the
minal side of the nucleus, so that there was not a row of nuclei in the

zone of mucin. The fourth case showed the luminal row of cells to be

| ~~ taller still; their nuclei were darker stained than in the basal layers, and

mucin was present on both sides of the nucleus, so that there was a red
zone with a row of nuclei just within it. In none of these four cases was
the epithelium thrown into folds. In the fifth case the luminal row of
cells was both taller and broader; the nuclei were situated near the middle
of the cells, stained deeply, and were irregular in shape as if from com-
pression. The mucous membrane was thrown into small folds and had

1 The expenses of this research were defrayed by grants from the Graham Research
Fund.

Mucinous Changes of the Vaginal Epithelium in Pregnancy 31

the appearance of being too large for the submucous layer. The cases in
this class, formed of all the early pregnant guinea-pigs, thus present a

series showing a gradual increase in the size of the luminal row of cells
and in the amount of mucin they contain.

The six members of the second class resembled the fifth case fairly
closely. In two of them the folds of the mucous membrane were much
more marked and resembled those of the last class. The mucous membrane
of the seven cases of late pregnancy were identical in every respect. The
folds were so numerous that they had become contiguous, producing the
appearance of an epithelium of eight or more layers of cells. When care-
fully examined, however, the epithelium was seen to be composed of the
same cells as in the first stage—namely, a basal layer of one or two rows of
very flattened cells with clear nuclei and no mucin, and a luminal row of
tall expanded cells, greatly distended with mucin and having deeply
stained, compressed nuclei situated about the centre.

From these facts it may be. concluded that in guinea-pigs during
pregnancy the vaginal epithelium gradually becomes both thicker and
broader from an increase in size of the cells in the row next the lumen
owing to their distention with mucin. The process appears to be complete
some time before term in the latter half of pregnancy.

Twelve guinea-pigs have been examined at known intervals after
parturition. In all twelve the young lived and went on sucking till the

mothers were killed. In one, less than twenty hours after parturition,

the vaginal epithelium resembled that deseribed at full term in every

respect except that the basal, non-mucinous cells were not so flattened,

so that this layer was more conspicuous. ‘lwo were examined five days
after parturition. In these the folds of mucous membrane showed irt ‘tvals
between them as if they had shrunk away from one another; the muela

layer was rather thinner, and in it were numerous clear spaces, many of
which contained leucocytes. Two cases, ten days after parturition, differed
from each other. One showed simply a more advanced vacuolation
and thinning of the mucinous layer than the five-day cases; the other
resembled the early pregnancy cases, the epithelium having two to three
layers of cells, those next the lumen being columnar loaded with mucin,
and, having their nuclei near the middle, small folds were present. Three
cases, fifteen days after parturition, showed thinning and vacuolation of
the mucinous layer; but in one it was not more marked than in the ten
cases. One case, twenty days after parturition, had an epithelium com-
pletely free from mucin: it was stratified in the ordinary way four to six
cells deep; all the cells contained nuclei, and leucocytes were present
between some of the cells in the layer next the lumen. Three cases were

32 Mr F. J. F. Barrington

examined respectively thirty, forty, and fifty days after parturition ; they
all showed a mucinous layer next the lumen with advanced thinning and
vacuolation. Folds were fairly well marked in the thirty-day case, but
absent in the other two. :

These observations, though not constant enough to draw any definite
conclusions, show that soon after parturition the mucin begins to disappear.
The rate of disappearance either varies considerably in individual cases or
some other process occurs in the epithelium, apart from pregnancy, and
becomes superimposed at varying intervals of time after. It further
appears that usually, under natural conditions of lactation, the mucin is
not cast off en masse; in only the twenty-day case could this have occurred
in the twelve above described. In a guinea-pig killed six days after
parturition, the young having died after one day, the vaginal epithelium
was stratified and free from mucin as in the twenty-day case. Still
adhering to the epithelium in some places and quite free from it in others
was the whole thick mucinous layer with a layer of leucocytes between it
and the epithelium. The mucinous layer was very thick and not greatly
vacuolated, so it seems that in this case the basal, non-mucinous cells must
have proliferated as soon as lactation ceased and the separation of the
mucinous layer have been brought about by the layer of leucocytes.

In Non-pregnant Guinea-pigs—Forty-four guinea-pigs which had no
visible uterine enlargements were examined. None of them were known to
have recently given birth, and in none was the uterus subinvoluted. It is
probable that among the forty-four cases there were a few which were
pregnant at too early a stage to give uterine enlargements, and possible
that parturition had occurred in others a week or more before. The
vagina] epithelium in these forty-four cases showed great variations, and
all Stages described as occurring in pregnancy and the puerperium were
found except that seen in the last half of pregnancy. The cases fell into
five groups :—

Group 1 (seven cases).—The epithelium consisted of three to five
layers of cells. The cells in the layer next the lumen were distended with
mucin, and this layer was thrown into folds; the folds were contiguous,
giving rise to the appearance of several layers of mucinous cells. These
seven cases were those which most closely resembled the condition seen in
the last half of pregnancy ; they differed from it in the smaller development
of the mucinous layer, and in the greater number of basal layers free
from mucin.

Group 2 (sixteen cases).—The epithelium was stratified and consisted ©
of four to six layers. Mucin was either completely absent or a very faint
pink tinge was seen in some of the flattened cells next the lumen.

Mucinous Changes of the Vaginal Epithelium in Pregnancy 33

___It-is quite clear that the condition seen in Group | is the stage which
cedes that seen in Group 2, the latter being produced from the former
the casting off en masse of the mucinous layer. Group 1 contains
where this layer is cast off in places and adherent in others, and
oup 2 contains cases where the whole mucinous layer is cast off and lying
2 in the vaginal lumen.
Group 3 (six cases).—The epithelium was stratified, consisting of three
to five layers of cells. The row of cells next the lumen gave a well-marked
_ mucin reaction.

_ This group only differs from the last in the epithelium being rather
thinner and in the presence of mucin in the luminal layer.
Group 4 (nine cases).— These exactly resembled those described already
being seen in early pregnancy. The epithelium consisted of one or two
rows of cells without mucin situated basally, with a columnar row, giving a
_ marked mucin reaction, next the lumen ; folds were absent or ill-developed.
_ In certain cases Group 4 appeared to shade gradually into Group 3 on
the one hand, and into Group 1 on the other.
_ Group 5 (six cases).—The epithelium resembled that already described
as occurring in the puerperium. The epithelium consisted of one or two
rows of mucin-free cells situated basally, with a row of mucinous cells next
the lumen ; folds were well marked but not contiguous, and marked cystic
_ formation was present in the mucinous layer. Some cases in this group
appeared somewhat similar to those of Group 4.
_ From an examination of this series it seems that the cycle passes
_ successively through Groups 1, 2, 3, and 4 in that order and then back to
Group 1. Group 5 appears also to arise from Group 3 and to show a
- second way in which the epithelium loses its mucin, but this, though
apparently the usual way in the puerperium, is less common apart from
_ pregnancy than the mucin being thrown off en masse.
It seems probable that the changes in the non-pregnant animal have
some connexion with the cestrous cycle, as I have shown to be the case
with the mucin in the cat’s Bartholin’s gland (Internat. Monatsschr. f.
Anat. and Phys., Bd. xxx. p. 1). Examination of the uteri and ovaries,
however, failed to give confirmatory evidence of this. The mere presence
‘of mucin does not appear to be dependent on the ovaries, since it can be
_ found in the luminal layer of cells in the full-term guinea-pig foetus. In
four guinea-pigs which were known to have littered, both ovaries were
_ removed and the animals killed four, four, nine and twelve months after
_ respectively. The vaginal epithelium consisted of two rows of cells, a
basal, compressed layer, free from mucin, and a columnar layer with mucin
next the lumen. In one of those killed after four months, well-marked

VOL. L. (THIRD SER. VOL. XI.)—OCT. 1915, 3

34 Mr F. J. F. Barrington

Fic. 1.—Vaginal mucous membrane of a guinea-pig during early pregnancy.
(Drawn from a Leitz No. 6 objective and No, 3 eyepiece.)

Fic, 2.—Vaginal mucous membrane of a guinea-pig pregnant at term.
(Drawn from a Leitz No. 6 objective and No, 3 eyepiece. )

_ Mucinous Changes of the Vaginal Epithelium in Pregnancy

—

Fic. 3.—Vaginal mucous membrane of a guinea-pig twenty days after parturition,
(Drawn from a Leitz No. 6 objective and No. 3 eyepiece. )

Fic, 4.—Vaginal mucous membrane of a guinea-pig one year after double ovariotomy.
(Drawn from a Leitz No. 6 objective and No, 3 eyepiece. )

35

36 Mucinous Changes of the Vaginal Epithelium in Pregnancy

folds were present, but not in the three others, which resembled each
other closely.

OTHER ANIMALS.

In the rat six individuals were examined. In three which were not
pregnant the vaginal epithelium was of the usual stratified form and
gave no mucin reaction. In one pregnant at term and another killed
within twenty-four hours of parturition the vaginal epithelium consisted of
one or two rows of flattened cells, free from mucin and situated basally,
surmounted by about six rows of cells distended with mucin. In these
sections it was not clear that the thickness of the mucinous layer was
due to reduplication of the mucous membrane. The sixth rat was killed
about a week after parturition, the young having died on the first day: the
epithelium was stratified with four to six rows of cells: the row of
flattened cells next the lumen gave a very faint mucin reaction.

Seven rabbits were examined. One had littered one to two days
before and another was twenty-two days pregnant. In these two the
vaginal epithelium consisted of two rows of cells. Those next the lumen
were tall, columnar, full of mucin, and had the nuclei near the bases.
The basal cells were very flattened and much fewer in number than those
in the luminal row; they were free from mucin. In the five others, which
were not pregnant, the epithelium was stratified in three to five rows.
One contained no mucin: in one the luminal row was rich in mucin, and
columnar; in the remaining three there was a small amount of mucin in
the luminal row. '

As far as pregnancy is concerned, the rat and rabbit appear to resemble
the guinea-pig in the changes which take place in the vaginal epithelium.

In cats four individuals were examined. Two were in the latter half
of pregnancy. The stratified epithelium had flattened cells next the
lumen, a few of which gave a faint mucin reaction: mucin was present
in some of the vaginal crypts. Parturition had occurred in the two others
recently ; in one less than twenty-four hours before death. In these no
mucin was found in the epithelium.

Four hedgehogs were examined. One was in the latter half of
pregnancy. The other three, which were not pregnant, were killed
respectively in January, May, and September. No mucin was present
in the vaginal epithelium in any case.

In the three rodents examined, therefore, a marked change takes place
in the vaginal epithelium in pregnancy. This change consists in a great
increase in the size of the cells next the lumen owing to their distention
with mucin, This change does not occur in the cat or the hedgehog.

- SOME ABNORMAL DEVELOPMENTS IN THE VASCULAR SYSTEM

OF THE FROG (RANA TEMPORARIA). By Watrer E.
CoLLINGE, M.Sc., F.LS., ete., Research Fellow of the University
of St Andrews, The Gatty Marine Laboratory, St Andrews.

NuMEROUS abnormalities in the vascular system of the frog have been
described by different observers, and probably a still greater number have
been noticed, but not recorded. The series here described have all been
met with during a period of about three years. A few occurred in the
ordinary course of practical work in the zoological laboratory, but the
majority have been found in the course of a large number of dissections
made expressly for the purpose. Upwards of five hundred specimens
have been examined and twenty-two abnormalities observed, the more

. important of which are here described.

Some of these are interesting as illustrating the persistence of embryonic
stages, whilst some of the remainder may possibly be regarded as reversions
to ancestral conditions.

No. 1—In the developing frog we have present a median caudal
continuation of the united posterior cardinal veins, usually known as

the caudal vein. The lateral portion of these united cardinals ultimately

forms the anterior part of the reni-portal veins of the adult and the median
portion of the inferior vena cava, the caudal continuation disappearing.!
In the specimen here figured (fig. 1) the caudal vein has persisted, and
is seen as a posterior prolongation of the inferior vena cava, which is
continued backwards to the posterior boundary of the abdominal cavity.
No. 2.—This abnormality occurred on the left side of the body only.
It is somewhat similar to one described by Shore,’ only rather more pro-
nounced. The reni-portal vein is here continued forwards on the outer
border of the kidney, and curving round the anterior end of that organ
it opens directly into the inferior vena cava. From the posterior end of
the kidney the vein gradually enlarges in size; after receiving two lumbar
veins it becomes still more prominent, until at the anterior border of the
1 Cf. Milnes Marshall, Vertebrate Embryology, 1893, p. 184; also Shore, “On the
Development of the Renal-Portals and Fate of the Posterior, Cardinal Veins in the Frog,”

Journ. of Anat. and Phys., 1901, vol. xxxvi. p. 37, fig. 14.
2 Shore, “Unusual Arrangement of the Renal Portal Vein in the Frog,” Journ. of

Anat. and Phys., 1900, vol. xxxiv, pp. 395-402.

38 Mr Walter E. Collinge

kidney it is quite double the normal size of this vein. I agree with Shore?
that the most probable explanation of this abnormal vein “is that it is
a persistent part of the left posterior cardinal vein, which normally
disappears during the later parts of larval life.”

No. 3.—This interesting abnormality is probably to be explained in
the same manner as No. 2, but curiously the left reni-portal vein is
entirely absent. On the right side the femoral, sciatic, and pelvic veins
are perfectly normal, the former two uniting as usual to form the reni-
portal vein, which, instead of passing to the outer border of the kidney,
traverses the ventral surface of that organ, slightly posterior to its middle

is ive.
f

RAG

aa ee

Fie. 1.—Persistent caudal Fic. 2,—Abnormal reni- Fic. 3.—Reni-portal vein con-
vein. portal vein. tinuous with inferior vena
cava.

and gives off two small veins to the substance of the kidney, and then
passing forwards and towards the median line it enters directly into the
inferior vena cava. On both right and left sides there are only three
renal veins. The femoral on the left side is normal as far as the position
where it should unite with the sciatic; but as there is no reni-portal on
this side, the whole of the blood from both of these veins must be returned
to the heart by way of the pelvic and anterior abdominal veins.

Nos. 4, 5, 6, and 7.—These four are all concerned with the reni-portal
vein. In No. 4 the vein bifurcates to form a loop before reaching the
kidney as a single vein. In No. 5 a somewhat similar condition obtains,
only there is a small commissure connecting the two sides. In No. 6 the
bifurcation commences at the junction of the sciatic and femoral, so that

1 Op. ecit., p. 401.

Abnormal Developments in the Vascular System of the Frog 39

_ we might ‘speak of two reni-portal veins on the left side. In No. 7 we
have a very peculiar looping of the femoral, and the sciatic somewhat

__ abnormal, but the chief interest in this specimen lies in the persistence of

what might be described as the anterior portion of the right reni-portal.
This I regard as a portion of the right posterior cardinal sinus, although
there is no connexion anteriorly with the heart. In No. 8 we have
this connexion.

No. 8.—In this specimen a vein branches from the anterior extremity
of the right reni-portal vein, which latter vein is continued a little more
anteriorly than usual. The vein passing from it traverses the body cavity

yp

E-pr--

f-----

Fie. 4.—Looping of the Fic. 5.—Looping of the Fic, 6.—Double reni-
reni- vein. : reni-portal vein. portal vein,

on the right side and ultimately opens at the junction of the subclavian
vein and the right anterior vena cava. Here again we have a persistence
of the embryonic right posterior cardinal sinus.!

Nos. 9 and 10.—These illustrate two most interesting cases in connexion
with the anterior abdominal vein. Buller? has described a case somewhat
like No. 9. In this specimen the anterior abdominal vein is quite normal
in the medio-ventral line of the abdominal wall; on reaching the region of
the liver it joins with the hepatico-portal vein and a large branch is given

off to the left lobe of the liver, but the right branch, a much finer one,

_. 1! OF Hochstetter, Morph. Jahrb., 1888, Bd. xiii, and Anat. Anzeiger, 1888 ; also Shore,

2 P'Bulles, * Abnormal Anterior Abdominal Vein in a Frog,” Journ. of Anat. and Phys.,
1896, vol. xxx. pp. 211-214, fig.

40 Mr Walter E. Collinge

passes to the right superior vena cava. We undoubtedly have here the
persistence of an embryonic character, but whether it also represents “a
case of reversion to an ancestral stage, slightly in advance of that reached
by Ceratodus, and therefore a case which, from its transitional character,
tends to some extent to bridge over the gap between the Dipnoid and the
normal Amphibia,” as assumed by Buller, I am not prepared to say, for
the evidence is as yet far too imperfect. Baldwin Spencer! in his account

Fic. 7.—Abnormal femoral, sciatic, and Fic. 8.—Persistence of the embryonic right
reni-portal veins. posterior cardinal sinus,

of the anterior abdominal vein of Ceratodus points out that it “ may in all
probability be rightly regarded as forming an anterior abdominal system
comparable to that obtaining in Amphibia; though at the same time there
are considerable differences between the two.”

In the normal development of the frog the right anterior abdominal
vein always disappears before the left. Milnes Marshall,” describing this,

1 Baldwin Spencer, Contributions to our Knowledge of Ceratodus, pt. i. “The Blood-
vessels ” (Macleay Memorial Volume).
2 Op. cit., p. 184.

- __ Abnormal Developments in the Vascular System of the Frog 41

tates: “The anterior abdominal vein is at first paired, and is in connexion,
ot with the liver, but the heart. The pair of vessels appear first in the
rentral body-wall, extending backwards a short distance from the sinus
yenosus ; they soon extend further backwards, and acquire communications

wit h the veins of the hind legs and of the bladder. At a later stage the
two anterior abdominal veins unite at their hinder ends, in front of the
r, while further forwards the vein of the right side disappears, the

e alone persisting. Later still, the anterior abdominal vein loses its

Fic. 9.—Persistence of the connexion with Fic. 10.—Persistence of the connexion with
the heart of the anterior abdominal the heart of the anterior abdominal vein
vein on the right side. on right and left sides.

ec communication with the sinus venosus, and acquires a secondary
ae » with the hepatico-portal veins, or afferent veins of the liver.”
______No. 10.—The occasional persistence in the adult frog of a condition
th as is described above in the developing frog has long been suspected
yy those interested in the subject, but I am not aware that it has hitherto
ctually been observed.
Fig. 10 illustrates a case where this embryonic condition has persisted.
Here the median anterior abdominal vein passes forwards in the normal
manner. It has no connexion with the liver, but divides into right and left
branches before reaching the region of that organ. These branches pass
forwards one on each side and open into the right and left superior ven

42 Abnormal Developments in the Vascular System of the Frog

cave respectively. On the right side the vein opens very close to the sinus
venosus, but on the left side it is rather farther away.

Of the remaining abnormalities observed, two were identical with that
described by Shore,! showing a connexion between the reni-portal and
pulmonary veins. Two others showed a small vein entering the commence-
ment of the anterior abdominal vein, just in front of the united pelvic

a. ab.

Fic. 11.—Additional vein joining the Fre. 12,—Abnormal pelvic vein.
anterior abdominal vein.
vein (fig. 11), which small vein was formed by two finer branches coming
from the region of the bladder. In two other cases (fig. 12) the pelvic of
the right side was formed by two branches from the femoral.
The remaining abnormalities were of only minor importance.

1 Op. cit. 1901, p. 324.

REFERENCE LETTERS.

a.ab, Anterior abdominal vein, l.s.v.c. Left superior vena cava.
ce. Caudal vein. p. Pelvic vein.
ex,j. External jugular vein. r. Renal veins.
jf. Femoral. yp. Reni-portal vein.
h.-p. Hepatico-portal vein, r.s.v.c. Right superior vena cava.
int,j. Internal jugular vein. sc. Sciatic vein.
z.v.c. Inferior vena cava. subel. Subclavian vein.
k. Kidney. subse. Subscapular vein.
L. Liver. / s.v, Sinus venosus,

Z. Lumbar vein.

ae
me

= ON THE PRESENCE OF GENIAL TUBERCLES ON THE MANDIBLE

OF MAN, AND THEIR SUGGESTED ASSOCIATION WITH
THE FACULTY OF SPEECH. By Arruur Tuomson, Professor
of Human Anatomy, University of Oxford.

_ Ara time when so much interest is centred around the discovery of early
human remains, it may not be amiss to draw attention to certain considera-
tions in relation to the morphology of man’s mandible which may have a
bearing on the elucidation of some of the problems which have arisen in
connexion with the inferences to be deduced from a study of the osseous
fragments. Confining my attention, meanwhile, to the study of the lower
jaw, we have now a considerable number of “ fossil” specimens that display
characters which may be regarded as unusual in living races. Among
these we may mention the reduction in size of the mental protuberance
and tubercles as displayed in the famous Heidelberg jaw, and also ex-
emplified in the mandibles from Spy, that of Naulette, the Moulin Quignon
jaws, La Chapelle aux Sainte and the Moustier remains, all of which exhibit
an ape-like appearance in the slope of the anterior symphysial surface.
As long ago as 1867 Broca® drew attention to this condition, and clearly
proved that instances were to be met in the mandibles of recent races, in
which these characters were as pronounced as in the case of the so-called
fossil types. He illustrated this in his memoir by a figure of the mandible
of a New Caledonian, and I am fortunate enough to be able to confirm
this observation by an equally well-pronounced specimen from the same
locality, at present deposited in the Williamson collection of skulls (No.
300) of the Royal Army Medical Corps at Millbank, London. This New
Caledonian mandible, of which I give a figure (fig. 1), exhibits the same
roundness and absence of chin as that represented by Broca, and sets at
rest the assumption that there is anything exceptional in the occurrence
of a like or similar condition in the jaws of fossil man. That the occur-
rence of this type of mandible is not very unusual is common knowledge,
though it is rare to meet with it in such characteristic form as that

1 The substance of this paper was communicated to a meeting of the Anatomical Section
of the International Congress of Medicine held at the Royal College of Surgeons, London,
on 11th August 1913, but its publication has for various causes been delayed.

2 Mémoires d’anthropologie, tome ii. p. 146.

44, Professor Arthur Thomson

exhibited in the figure. It is not with this feature, however, that I am
immediately concerned.

Equally interesting is the observation that in some of the fossil
mandibles there is a pit or fossa in place of the raised tubercular area to
which the genial muscles are attached in man. This has led to many
surmises as to its significance; for, whilst most have agreed that the
occurrence of this anomaly points to a similarity between it and the
appearance exhibited in the anthropoid apes, not a few have assumed that
the presence of such fosse is indicative of a feeble development of the
muscles attached thereto, and in particular of the genio-glossus; and in
consequence have suggested, nay, well-nigh decided, that the occurrence

Fic. 1.—Mandible of New Caledonian.

of this feature was an indication that man had not yet reached ‘that
stage in his evolution when he had acquired the faculty of articulate
speech. So far-reaching an assumption demands our most serious con-
sideration before we can admit its acceptance.

The appearance of the lingual surface of the symphysial part of the
mandible in the anthropoid apes is so well known that little time need be
spent on its description. In place of a tubercular area for the attachment of
the genial muscles, such as we meet with in man, the corresponding site
reveals a well-marked fossa or hollow, which may conveniently be called the
genial fossa; the depth of this fossa is still further emphasised by the
presence of a transverse ledge or shelf which unites the lower borders of
the body of the mandible on either side, behind and below the symphysis.
This, oftentimes known as the simian ledge, may be better termed the
digastric plate, for reasons that will hereafter be explained. The presence
of this ledge in the apes materially shortens the arch of the jaw inferiorly,

7 Se Oe :

On the Presence of Genial Tubercles on the Mandible of Man 45

ae _ and so limits to a corresponding extent the area oceupied by the tongue and
___ its associated muscles, whilst at the same time it deepens the genial fossa,
and so renders more striking the contrast between the appearance

displayed in this region in the ape and that exhibited by man in the
corresponding situation.
On a more careful examination of this region in the anthropoids, it will

_be seen that there are individual differences exhibited in the appearance of

the parts in members of the same species.

In the gorillas I examined, I met with a more pronounced bulge on the
upper part of the posterior surface of the symphyses in some instances
than in others, in consequence of which the thickness of the mandible
was much increased, measuring in one specimen as much as 27 mm. with
a thickness of 20 mm. through the bottom of the genial fossa, whilst in
another equally mature specimen of the same sex the corresponding
measurements were only 19°5 mm. and 12 mm. respectively.

In consequence of this difference in the symphysial thickness, there was
exposed in the latter example a larger area of the upper surface of what
I may term the digastric plate, and thereby a greater appearance of depth
was imparted to the genial fossa. Usually the floor of the fossa was

_ pierced by a pair of vascular foramina, one on either side of the middle

line. Sometimes these foramina were not of equal size and not necessarily
on the same horizontal line. A median crest, but faintly marked,
appeared above, between these two foramina, and, running downwards,
passed over the upper surface of the digastric plate to end inferiorly on its

posterior margin in an irregular tubercle, sometimes double. On either

side of this median line the bone was occasionally slightly roughened,
suggesting the attachment of tendinous fibres to its periosteal surface.
There was nothing to indicate the precise attachment of the genial

_ muscles, and it was impossible to differentiate between the attachment of

the genio-glossus and the genio-hyoid. They might, from such indications
as appeared on the bone, have been a combined mass, the position
of the median line merely serving to separate the right and left fleshy
masses from each other.

In two of the Oxford gorillas the under surface of the digastric plate
exhibited different features; in one (a#@) it was smoothly confluent with
the rounded surface of the sloping symphysis externally, whilst in the
other (bb, 2052) it was recessed within the converging margins of the
lower borders of the jaw, which swept anterior to it to meet in front at a
point which may be regarded as the inferior extremity of the symphysis,
assuming that to be independent of the digastric plate.

These appearances suggest the necessity of a further inquiry as to the

46 Professor Arthur Thomson

precise attachment of the various muscles connected with the bone in this
region, for possibly that which I have designated as the digastric plate
may in all probability be a more extensive surface for the attachment of
the genio-hyoid. .

In the Oxford chimpanzee (2049 6) the maximum symphysial thickness
was 13°5 mm.; the minimum thickness of the bone between the bottom of
the genial fossa and the external surface of the symphysis was 55 mm.
From the fossa, which was funnel-shaped, there passed a deep pit into
which there opened three foramina of unequal size.

The upper surface of the digastric plate, which in this instance was
short, was unmarked by a ridge, but its posterior edge was emphasised by
the presence of a short and stunted spine situated in the middle line. The
under surface of the digastric plate was everywhere confluent with the
rounded surface of the mental part of the bone.

On either side of the middle line, 13 mm. below the alveolay border,
there was a small vascular foramen with a groove leading up to it.

In the orang the arrangement closely resembles that of the gorilla. In
one specimen (ad) belonging to the Oxford collection the maximum thick-
ness of the symphysis was 18°5 mm.; the minimum thickness in corre-
spondence with the bottom of the genial fossa was 11 mm. In the other
example from the department of human anatomy the maximum thickness
was 19°5 mm.; the minimum at the fossa was 10 mm. In both, the fossa
was pierced by three vascular foramina, one large and two smaller; the
latter were placed one above the other, and lay in one specimen (d) to the
left of the middle line, in the other (H.A.D.) to the right. The larger
foramen in both examples pierced the bone on the opposite side to that
on which the smaller canals were situated. In both the digastric plate
was well developed, though in one its upper surface was more extensive
than the other. In each case there were indications of a faint mesial line
which blended posteriorly with a small tubercle on the posterior edge and
slightly on the under surface of the plate. On either side of the median
line the bone was slightly rough as if for muscular attachment. Inferiorly
and externally the under surface of the digastric plate in specimen H.A.D.
was everywhere confluent with the surrounding surface without the
faintest trace of any muscular impressions. In specimen d there were
indications of a rounded elevated crest inferiorly, bounded on either side
by a faint line which swept back on either side along the inferior border
of the horizontal ramus, suggesting the posterior limit of the attachment
of the anterior bellies of the digastric muscle thereto.

In man, as contrasted with the apes, this region usually displays a
somewhat lozenge-shaped elevated tubercular area corresponding to the

On the Presence of Genial Tubercles on the Mandible of Man 47

attachment of the genial muscles. This area is frequently surmounted

by a pair or two pairs of tubercles; in some cases the lower pair unite to
form a median crest, but great variety in the arrangement of these parts
is met with. At times all the tubercles may unite to form a median crest
with a projecting spine of from 3 to 5 mm. long arising from it; at other

_ times the surface of the bone here is quite smooth, with no spines or any

indication of muscular attachment.

The genial muscles here attached are the genio-glossi, passing from the
upper pair of genial or mental spines, just mentioned, to the tongue; and the
genio-hyoid muscles, which arise from the lower pair of spines and reach
the hyoid bone. It will thus be obvious that by means of these muscles
the lingual surface of the symphysis is brought into direct relation with
the tongue and hyoid apparatus.

Now, whilst it is admitted that there are great differences in the
appearance of what we may term the genial area in man, yet it has been
assumed that it is only in the jaws of fossil man that it ever exhibits an
arrangement comparable to that characteristic of the anthropoids, and it
has been accordingly urged that possibly the condition involving the
disappearance of the genial spines and the substitution for them of a
fossa was to be accounted for on the supposition that the fossil types
exhibiting this ape-like feature were at a stage in their evolution when
speech was as yet either undeveloped or but imperfectly practised.

This theory, which was first propounded by Mortillet, has received
ardent support from Walkoff,! who lays stress on the fact that the appear-
ances exhibited by the cancellous tissue of the symphysial part of the
mandible in man exhibit striking differences from that displayed in the
jaws of anthropoid apes. Apart from the structural differences dependent
on the setting of the larger teeth in the apes, he proceeds to demonstrate
that the osseous trabeculz respond to the strain induced by the attachment
of the genio-glossi and digastric muscles, and in this way explains the
characteristic form of the anterior part of man’s mandible. He regards
this development as particularly associated with the use of the genio-glossus
muscle as concerned in speech, more especially in the production of the
dental sounds. Be that as it may, because in man, in the majority of cases,
we find those spines to which the genio-glossi are attached well developed,
it is assumed that this indicates an activity of action which can only be
explained on the assumption that it is associated with some attribute
peculiar to man, and, failing. any other explanation, it seems plausible to
associate it with speech.

As we have seen, the development of the digastric plate or simian

1 “ Menschenaffen : Studien iiber Entwickelung und Schiidelbau,” Selenka, Band ii.

48 Professor Arthur Thomson

ledge is correlated with the traction effects of the digastric muscles, which
are relatively large and strong in the apes, and which of necessity, from
the greater length of the mandible, must exercise a more powerful traction
effect on the bone than in the shorter jaw of man. The effect of this is,
that in the ape the lower border of the symphysis is pulled backwards
independently of the rest of the bone, and so a ledge is formed which not
only affords an extensive surface for the attachment of the digastries
inferiorly, but also by its inclination at an angle with the rest of the
bone provides a recess in which the genial muscles are received.

Now, the manner in which tendons are attached to bones varies
greatly. In those in which the moment of the contraction of the muscles
is concentrated in a rounded tendon of limited extent, we find that the
attachment to the bone is marked either by a pit or a spine. Both serve
the same purpose, viz. to increase the area of attachment of the tendinous

\\/ Mf

Fie. 2.

fibres, as may be illustrated by a simple diagram. It is only natural to
suppose that when the tendon 1s attached to a surface which is otherwise
plain, the bone will react to the stimulus of the muscle and a spine will
be produced within the substance of the tendon; whereas when tlie
tendon is attached to a surface not plain but having its parts arranged
in angular or curved fashion, the tendon will, so to speak, take advantage
of the recessing, and the bone will tend to grow up around it.

In the anthropoids, owing to the development and backward extension
of the digastric plate, there is an angular recess formed between the lingual
surface of the upper part of the symphysis and the superior surface of
the digastric plate; into this the genial muscles are attached, and it is
only where the genio-hyoids extend backwards over the upper surface
of the digastric ledge or turn round its posterior border that we have any
indication by crest or tubercle of their attachment, the attachments of
the muscles to this area being elsewhere indicated by a roughening of the |
periosteal surface of the bone.

But there are other factors which must be taken into consideration.

On the Presence of Genial Tubercles on the Mandible of Man 49

“Much stress has been laid by Walkoff and Topinard on the fact that this

region of the mandible in the apes is pierced by two, or more, vascular
foramina, placed usually one on either side of the middle line at the bottom
of the right and left halves of the genial fossa; these are not always of
equal size, and often open by funnel-shaped mouths, which deepen con-
siderably the fossa at the points where they leave it. The third foramen,
usually smaller, is placed lower down, and frequently pierces the bone in
the middle line, though occasionally it may lie to one or other side of
the median plane.

In man the arrangement of these foramina is somewhat different. I
find as a rule that there are three foramina to be seen on the lingual
surface of the symphysis in this region. In the majority of instances they
are disposed in the middle line: one immediately above the genio-glossal
spines—this may be distinguished as the supraspinous foramen; another,
situated usually between the upper and lower pairs of genial spines, may
for convenience be called the interspinous foramen; and a third foramen,
to be named the infraspinous, disposed below the spines for the genio-
hyoids, and placed in most instances on the lower border of the mandible
between the areas of attachment of the two digastric muscles. It may be
that one or other of these vascular canals is absent, but in a large majority
of cases, though their size may vary much, their position can readily be
recognised,

Whilst such is the arrangement more commonly met with. it is not
unusual to find cases in which one or other of these foramina is

duplicated and arranged one on either side of the middle line, thereby

displaying a variation which brings them more in accord with what is
the characteristic arrangement in the anthropoids. In my opinion, too
much stress is laid on the differences thus exhibited between man and the
apes, for in a considerable number of specimens I have examined I find
the disposition of these vascular foramina conforms with what we see in
the anthropoids. Thus, out of twenty-three Ancient Egyptian mandibles,
which I examined, I found two cases in which the supraspinous foramen
was double, two in which the interspinous foramen was double, and six
instances in which the infraspinous foramen was duplicated. In the
cases in which there were two supraspinous foramina, in both instances
one foramen lay at or near the middle line; in one case the second foramen
lay to the right of it, in the other to the left. In the double interspinous
foramina these canals lay on either side of the middle line. There were
also examples of foramina lying wide of the middle line ; thus this happened
three times in the case of the interspinous foramen.

Le Double, in discussing the source of the vessels which pass through

VOL. L. (THIRD SER. VOL. XI.)—OCT. 1915.

50 Professor Arthur Thomson

these canals, ascribes their origin to the sublingual and to the submental
branches of the facial, the latter probably supplying the vessel which enters
the infraspinous foramen, the former furnishing the twigs which enter the
supraspinous and possibly the interspinous canals. There seems evidence,
too, to suggest that in the case of the foramina being situated in the
middle line and single, the branches which they receive are derived from
the arterial trunks of the left side. In view of these variations, and
considering how prone the vascular system is to anomalies in its distribu-
tion, particularly when this concerns its ultimate ramifications, there
seems little justification for attaching much peat Sea 2 significance to
such minor details.

The evidence that has been adduced from the Egyptian mandibles is
amply supported by a more extended survey. The point is one which I
have not had an opportunity of verifying in all the human mandibles I
examined, for at the time at which I made my more extended inspection
of these jaws I was not particularly interested in this feature; but I have
since examined the mandibles in the Oxford collection, and I find ample
confirmation of the results already described in connexion with the
Ancient Egyptian jaws.

Bearing in mind the numerous examples met with in human morphology
of instances where a spine marking the attachment of a tendon is some-
times replaced by a fossa, I undertook a search through a large series of
human crania to see whether, perchance, the same might not occur in
regard to the genial spines, and it is the result of this inquiry which I
now propose to submit.

The collections included that of the Royal College of Surgeons of
England, numbering 2911 specimens; the Williamson collection at the
Royal Army Medical College, embracing 572 crania; and the Rolleston
collection at Oxford, numbering 498, supplemented by others in the
Department of Human Anatomy; the grand total amounting to over 4000
skulls. Out of this number of skulls about 1670 mandibles were examined.

For a long time I made little progress in my search; for although
remarkable variations were exhibited in the arrangement and develop-
ment of the genial spines, little or no evidence could be got of a distinct
pitting. I was encouraged to proceed, however, by the fact that in a large
percentage of cases the spines were absent and the place usually occupied
by them was quite smooth. At last I lighted on an example which gave
evidence of pitting, in the place of the attachment of the genio-glossus,
and, thus stimulated, I pursued my search with more hope. At last I
came upon certain specimens which proved beyond a doubt that examples
of the tubercular area being replaced by a fossa may and do occur in rare

On the Presence of Genial Tubercles on the Mandible of Man 51

instances in mandibles representative of the living races of man. I shall
first describe the specimen which best exhibits this variation, and in which
the appearances displayed most approximate to the form characteristic
of the anthropoids, and then proceed to illustrate by examples what one
may term the transitions between the human and the anthropoid types.
The mandible in question was that of a Bushman (No. 1300.15 in the
collection of the Royal College of Surgeons). The teeth, which were all
present, were in perfect condition and somewhat worn; only in the case
of the incisors was the dentine exposed. The jaw, as may be seen in

Fic. 3.—Bushman. R.C.S., 1300.15.

the photograph (Plate I., top row), exhibited no unusual features when
viewed externally.

The vertical height of the symphysis is 30°5 mm.; the other measures,
taken in accordance with the instructions of the international agreement
for the unification of craniometric measurements, are as follows:

Bicondylar width, 102 mm. ; bigonial diameter, 89 mm.; length of ascending
ramus, 47 mm.; width of ascending ramus, minimum 34°5 mm., maximum 37°5
mm.; height of the body of the mandible opposite interval between first and
second molar teeth, 25 mm. ; maximum thickness of body in plane passing between
first and second molar teeth, 14 mm.; mandibular angle, 120°,

The most marked features of the bone are the openness of the angle, the
low ramus, and the marked thickening of the body (16 mm.) opposite the
interval between the second and third molar teeth, where it narrows so

52 Professor Arthur Thomson

that its vertical height is only 21 mm. The symphysial region, as viewed
anteriorly, exhibits a well-marked mental prominence in the middle line,
with two mental tubercles 22 mm. apart on its lower border; in these
respects it exhibits characters which are essentially human.

On turning now to the lingual surface of the symphysis, a very unusual
arrangement is displayed (fig. 3, and Plate I., top row). Within and behind
the mental prominence there is a very definite fossa, which easily admits
the pulp of the index finger. Above this the surface of the bone is slightly
convex, and measures 6 mm. in maximum thickness from back to front.
As will be seen from the section taken from a plaster cast of the jaw
(see Plate I., top row), this convexity follows the curve of the concavity of
the upper part of the symphysis anteriorly. The lower part of the fossa
is limited below by a very distinct bar of bone confluent with the inferior
border of the body on either side, and also to some extent continuous
above with the anterior extremities of the mylo-hyoid ridges.

In consequence of this arrangement we have the surfaces for the
attachment of the anterior bellies of the digastrics directed downwards,
instead of obliquely downwards and backwards as is the more usual dis-
position in man. Here, then, we have an arrangement which is precisely
comparable to that exhibited in the anthropoids, where the muscles arise
from the under surface of the digastric plate; with this difference only,
that, whereas owing to the absence of the mental prominence the anterior
surface of the symphysis forms with the under surface of the digastric
plate a uniform flowing curve, we have in this instance a marked mental
prominence with which the digastric plate is fused. Otherwise in every
respect the disposition of this the basal part of the symphysis in this
specimen corresponds fairly accurately to what has been described as a
characteristic feature of the ape. Having already seen that the absence
of a mental prominence cannot be regarded as strictly confined to the
anthropoids, since we have already noted that this “specific character” is
also lacking in some New Caledonian jaws, it need only be pointed out that
were it possible to procure a specimen—and this is by no means improb-
able—combining the appearances figured in the New Caledonian mandible
with those exhibited by this Bushman jaw, we would have a type of
mandible which would approximate very closely in many of its features
to that of the anthropoids. The fact that singly these variations may
occur in man is no reason why they should not appear in combination—
nay, it increases the probability of such occurring.

But to return to the fossa. In all its appearances it resembles what
we see in the orang. There are no spines or tubercles, but only a slight
roughening of the periosteal surface of the hollow, with a slight sugges-

On the Presence of Genial Tubercles on the Mandible of Man

54 Professor Arthur Thomson

tion of a median groove running downwards over the upper surface of
the digastric plate. There are two vascular foramina in the middle line,
which I take to be the supraspinous and interspinous canals; and on the
right side, 4 mm. from the middle line, the floor of the fossa is pierced by
another foramen of considerable size. On the under surface of the
digastric plate and close to its posterior margin there are two small
foramina transversely side by side in the middle line; these 1 assume
represent the infraspinous foramina of which we have already spoken.

The importance of this specimen seems to me to be that it refutes, once

Fic. 4.—Eskimo, Oxf, Univ., 855.

and for all, the suggestion that absence of the superior genial spines or
their replacement by a fossa is to be taken as evidence that the mandible
displaying those features belonged to an individual who could not talk,
or, if he did, spoke but imperfectly. For here we have an example
taken from an individual belonging to a race which, even admitting
it is degenerate, exercised to the full its powers of articulate speech.
The occurrence of this anomalous condition in the Bushman race will be
again referred to after we have considered other examples of a like or
similar nature. 7

The next specimen is the mandible of an Eskimo (No. 855 in Oxford
collection) (see Plate I, second row from top). Only the right second
molar tooth is im sitw; it exhibits the obliquely ground surface characteristic
of this race. The other teeth have been lost post mortem. On either

a
’

On the Presence of Genial Tubercles on the Mandible of Man 55

side, in- correspondence with the roots of the first molars there is evidence

of there having been abscess cavities during life; the third molars have
either not been cut, or have been shed.

Viewed from the side, the mandible has much the same configuration
as that displayed by the last specimen. Unfortunately, it is somewhat
damaged in places, both condyles having been knocked off and the posterior
edge of the ramus on each side being broken. Its measurements are:

Bicondylar width, —; bigonial diameter, 124 mm.; length of the ascending
ramus, 54 mm.; minimum width of ascending ramus, 44 mm.; maximum width
of ascending ramus, 49 mm. ; symphysial height, 33 mm. ; height of the body of
the mandible, 28-5 mm.; maximum thickness of the body of the mandible,
16-5 mm.; mandibular angle, 110°.

There is a well-marked mental prominence, but the mental tubercles
are not pronounced.

On the lingual surface of the symphysis (fig. 4) there is a slight convexity
overlying the roots of the incisor teeth; this sinks inferiorly into a trans-
versely oval fossa, the lower wall of which is formed by the sloping
surface of a well-marked digastric plate, the posterior border of which is
thick and rounded, whilst its under surface affords attachment for the

_ anterior bellies of the digastric muscles.

The fossa, which is not so circumscribed as in the last specimen, fades
away on either side into what may more properly be described as the
area overlain by the sublingual gland. In the middle line, and piercing
the floor of the fossa, are seen the supraspinous and interspinous foramina ;

whilst on the right side 7 mm. from the middle line there is another

vascular canal. On either side about 8 mm. from the middle line there
are vascular openings on the under surface of the digastric plate, which
presumably represent the infraspinous foramina. On either side and
below the supraspinous foramen there are two short slightly elevated
ridges, the representatives of the superior genial spines; whilst within
and below these another pair of feebly marked elevations extend down-
wards over the sloping surface of the digastric plate—these indicate the
attachments of the genio-hyoid muscles. The section given (Plate I., second
row from top), taken from a cast, exhibits the relations of the fossa to the
mental prominence and indicates the disposal of the surfaces of the
digastric plate. As will have been gathered from the above account, this
specimen differs from the Bushman mandible already described, in not
having the fossa so definitely circumscribed, and also in displaying evidence
of the position of the genial spines; it agrees with it, however, in having
much the same arrangement of the digastric plate and having the same
number and arrangement of vascular foramina.

56 Professor Arthur Thomson

In the mandible of another Bushman (No. 1300.1 of the Royal College of
Surgeons collection) (fig. 5,and Plate I., middle row) there is a well-marked
genial fossa, but here the digastric plate is not so well developed as in the
two foregoing examples. The jaw, which has a complete set of well-worn
teeth in perfect condition, exhibits pronounced alveolar prognathism ; in
other respects it agrees in general form with Bushman No. 1300.15. Its
measurements are :

Bicondylar width, 104 mm. ; bigonial diameter, 89°5 mm. ; length of the ascend-
ing ramus, 40 mm.; minimum width of ascending ramus, 32 mm.; maximum

Fic. 5.—Bushman. R.C.S., 1300.1.

width of ascending ramus, 40 mm.; symphysial height, 26 mm.; height of the
body of the mandible, 24 mm.; maximum thickness of body of mandibles opposite
interval between one and two molars, 13°5 mm. ; opposite interval between two
and three molars, 16 mm. ; mandibular angle, 132°.

The mental protuberance is full, but not projecting ; there are no mental
tubercles. The upper part of the symphysis slopes forwards.

The lingual surface of the symphysis displays pronounced internal
prognathism, the surface overlying the roots of the incisors being full and
rounded, displaying much the same appearance as that exhibited in the
anthropoids. In the genial region, the bone is deeply pitted in corre-
spondence with the attachment of the genio-glossi; above and between
these hollows, which are separated by a slight median ridge, is the supra-
spinous foramen—a point of some importance, since the hollowing of the

4
=
ig
q
:
: ue
a

On the Presence of Genial Tubercles on the Mandible of Man 57

: bone isnot due to any opening out of the mouth of the foramen, but lies

below it, in the position usually occupied by the superior pair of genial
spines. Below the genial hollows the bone is full and rounded, but the
digastric plate is not so prominent as in the previous examples; it is on

‘ _ the upper surface of this rounded border that the impressions caused by

the attachment of the genio-hyoid muscles can be seen, though here there
are neither spines nor tubercles. On the inferior surface of the base of
the symphysis are the surfaces for the anterior bellies of the digastric,
which are directed obliquely downwards and backwards, and not directly
downwards as in the previous specimens. There is a recurved transverse
crest in the middle line, on the lower border of the symphysis between
the two digastric areas.

Above the deepest part of the fossa and 1 mm. to the right of the
middle line is the supraspinous foramen; but on the level which it would

presumably have occupied are two foramina, one on either side of the

middle line—the right 6 mm., the left 8 mm. away from the median
plane. There isa median infraspinous foramen behind the recurved crest
already referred to on the lower border of the symphysis.

No. 1431 (red) is the mandible of a Fijian in the museum of the Royal
College of Surgeons. All the teeth were present at the time of death,
but only three molars on the left side and the first and third on the right
side remain in situ. These teeth are slightly worn. Viewed from the
outer side (see Plate I., second row from bottom) the shape of this jaw differs
much from those already described. The ramus is high, the condyle
rising considerably above the level of the coronoid process; the mandibular
angle is rounded; and the symphysial height is the same as the height of
the body of the bone. The lower border of the body is gently curved
upwards, towards the symphysis. The mental prominence is full and
rounded, with a slight ridge leading upwards from it to the interval
between the two medial incisors. There are no distinct mental tubercles,
but the fullness of the mental protuberance is carried outwards on either
side on to the fore part of the body of the bone above its lower border.

The measurements are:

Bicondylar width, 114 mm. ; bigonial diameter, 98 mm. ; length of ascending
ramus, 64 mm.; minimum width of ascending ramus, 40 mm. ; maximum width
of ascending ramus, 41 mm.; symphysial height, 26 mm. ; height of body of
mandible, 26 mm. ; maximum thickness of the body of the mandible between first
and second molar teeth, 15 mm.; between second and third molars, 17 mm. ;
mandibular angle, 110°.

In this specimen the lingual surface of the symphysis displays a full
convex surface overlying the roots of the incisor teeth (fig. 6). Judging from

58 Professor Arthur Thomson

the size of the sockets, the canine teeth must have been unusually large,
which possibly may account for the fullness of the mandible, the bone
being here 11 mm. thick in its sagittal diameter. Below this, in place of
the superior genial spines there is a distinct hollow, the lower side of
which is formed by the rounded surface of the upper aspect and posterior
border of a well-marked digastric plate, the under surface of which is
clearly marked for the attachment of the anterior bellies of the digastric
muscle, between which it forms a thick and rounded base to the sym-
physis. In the middle line, in the bottom of the fossa there is a large

Fic. 6.—Fijian. R.C.S., 1431.

vascular foramen, the supraspinous foramen; 6 mm. to the left of this
and on the same level is another foramen. There is no interspinous
foramen, but the infraspinous foramen is clearly seen near the middle
line on the under surface of the digastric plate. There are no genial
spines, but the points of attachment of the genio-glossi are clearly seen
in the bottom of the fossa, below and on either side of the supraspinous
foramen. Inferior to this, the impressions for the genio-hyoids are seen
to run down and turn over the posterior border of the digastric plate, so
as to reach its under surface, where they end in a full roundness between
the two digastric attachments.

In a New Caledonian mandible (No. 1118 in the collection of the
Royal College of Surgeons) (see fig. 7 and Plate IL, bottom row) the
appearance presented by the bone displays some of the characters dis-

On the Presence of Genial Tubercles on the Mandible of Man 59

tinctive of that race. All the teeth except the first left molar had been
present during life, though only the last two molars on either side and
the two right premolars, together with the left medial incisor, are now
im situ. The jaw is remarkable for the breadth of its ascending ramus
and the flattened and expanded appearance of its massive condyles, which
are much eroded on their articular surfaces.

The mental protuberance is full and rounded above, but slopes back-
wards below. The mental tubercles are widely parted, and lie on the lower
border of the body 30 mm. wide of the middle line.

Fic, 7.—New Caledonian. R.C.S., 1118,

The measurements taken were as follows:

Bicondylar width, 121 mm.; bigonial diameter, 87 mm. ; length of ascending
ramus, 62°5 mm.; minimum width of ascending ramus, 40°5 mm. ; maximum width
of ascending ramus, 46°5 mm.; symphysial height, 29 mm.; height of body of
mandible, 29°5 mm.: maximum thickness of body opposite interval between first
and second molar teeth, 16°5 mm. ; mandibular angle, 110°.

The lingual surface of the symphysis is characterised by a full and
sloping surface over the roots of the incisors, which exhibit some degree
of alveolar prognathism. The sockets of the canine are unusually large,
which may account for the thickness of the bone, which here measures,
in the sagittal diameter, 13:5 mm. Below the convexity of this surface
there is a small fossa, into the bottom of which project two very small
pointed spines, around which can be seen the area of attachment of the

60 Professor Arthur Thomson

genio-glossi. Above these, in the upper part of the fossa, can be seen a
fairly large supraspinous foramen; whilst below them is an equally well-
marked interspinous foramen, below which there is a sharp median crest
which slopes downwards and forwards to the base of the symphysis,
where it ends in a prominent spicule of bone. In this mandible the
digastric plate is poorly developed, and the surfaces for the anterior bellies
of the digastric muscle are directed downwards and backwards. There
are two well-marked infraspinous foramina on the basal border of the
symphysis. There is, on the right side and on the same level as the
interspinous foramen, another vascular canal 10 mm. from the middle
line; equally well marked is another, on the left side, 16 mm. away from
the median plane.

These comprise some of the best examples I have seen of this condition,
and thanks to the kindness of Professor Arthur Keith I have been able
to take photographs of them, and have casts made as well. The latter I
found useful, because they enabled me to take sagittal sections through the
symphysis, thereby displaying in an effective manner the contours of the
mandible in this region. In the course of my investigations, however, I
came across some other examples, not so well marked, but of interest in
filling up the gaps between this unusual condition and the appearances
ordinarily displayed in recent human mandibles. I quote from my note-
book ; unfortunately, I have not full details as to the disposition of the
foramina met with, but sufficient proof has been already advanced to show
that the arrangement of these is very variable, and that oftentimes they
exhibit a disposition similar to that met with in the anthropoid apes:

In a Hottentot (No. Af. 2% of the Williamson Coll.) there is a smooth hollow
with indications of the superior pair of genial spines, below which is a rough area
for the genio-hyoids, defined inferiorly by the edge which limits the attachment of
the anterior bellies of the digastric muscle.

In the mandible of a native woman from the Luhenault district of Western
Australia (No. Aus. $9, Williamson Coll.) the area of attachment of the genial
tubercles is replaced by a shallow pit ; there are no spines below the fossa ; there is
a rounded tubercle which lies between the edges of the right and left digastric
areas, the upper surface of which is rough for the genio-hyoids.

Native of New South Wales (No. Aus. 2%, Williamson Coll.). It is doubtful if
this mandible belongs to the skull with which it is catalogued ; but on it, in the
genial region, there is a distinct hollow, at the bottom of which, and at the lower
edge, the tubercles are faintly marked; the base of the symphysis is full and
rounded,

Spaniard, slave-trader from Sierra Leone (No. E 39, Williamson Coll.). There is
a slight hollow, the bottom of which and the lower edges are tubercular for the
attachment of the muscles.

Male Yasinese from Garkuch (No. 630°, R.C.S.). There is a faint shallow fossa,
the bottom of which is rough and spiculate.

vamy

a.

On the Presence of Genial Tubercles on the Mandible of Man 61

oe

a
Maravar, native g ? of Madura (No. 656, R.C.S.). No genial spines, but slight

pitting in position of superior pair.

Australian ? from Kangatong, Victoria (No. 1064, R.C.S.). There is a
shallow transverse groove corresponding to the level of the superior pair of genial
spines, above which the bone rises in a well-marked rounded surface, whilst below,

on the level of the inferior spines, it slopes forwards and downwards. Had this

mandible possessed a transverse ledge like the anthropoids there would have been
a deep fossa, ‘Ihe spines are only just marked.

Bushman ? (No. 13.02, R.C.S.). This is the Bushwoman described by Flower
and Murie in the Journal of Anatomy and Physiology, May 1867. The mandible
exhibits a very small and shallow pit in the genial region. In this connexion it is
of interest to note that the authors of the paper mention the fact that this young
Bushwoman, aged about 21 or 23, spoke English fluently. No mention is made, in
the description of the muscular system, of the genial muscles.

Bushman (No. 1300.11, R.C.S.). In this mandible there is a slight general
hollowing in the genial region, but no spines.

Bushman (No. 1300.13, R.C.S.). Here there is a flattening of the genial
surface—one might almost say a hollowing —with slightly developed spines on it.

Zulu, ? (young Maganja negro) (No. 1285, R.C.S.). There is a dimpling of
the surface and a vascular foramen in the position of the superior pair of genial
spines.

African, West Coast, N’Javi tribe (No. 1579, R.C.S.). There is a small pit
about 7 mm. x 4 mm., with a vascular foramen opening into it ; there are no spines.

Negro, West Coast (No. 12544, R.C.S.). Has a little depression about 8 mm.

_x4mm._ In the position of the supergenial spines there is a vascular foramen, No

inferior genial spines, but a slight suggestion of a ridge.

Mandingo (No. 1515 red, R.C.S.). There is a well-marked transverse fossa
about 8 mm. x4 mm. occupying the position of the superior pair of genial spines ;
the inferior spines, which are only little tubercles, lie one on either side immediately

- below the fossa. There is a vascular foramen in the middle of the bottom of

the hollow.
?(No 760!, R.C.S.). There is a small shallow depression over position
of superior genial spines. A vascular foramen is present. The lower margin of
the fossa is full and prominent.

Sandwich Islander (No. 1098, R.C.S.), Here there is a shallow pitting over
and above the superior genial spines. The lower border is thick and rounded. _

Guanche, ¢ (No. 566, R.C.S.). There are two well-marked pits corresponding
in position to the upper pair of genial spines. '

African, West Coast (No. 1241', R.C.S.). The upper pair of genial tubercles
is replaced by two distinct pits ; the inferior spines are indicated by a slight ridge.

Native of New Hebrides (No. 1172°, R.C.S.). There is a well-marked transverse
groove 11 mm. long in the position of the superior genial spines. The bone, below
the groove, is rounded, but there is no indication of the inferior pair of spines.

African, West Coast (No. 1236!, R.C.S.). There is a transverse cleft corre-
sponding to the position of the superior spines, and a raised elevated surface, with a
median crest for the lower pair. :

African, West Coast (1564 red, R.C.S.). The condition resembles the previous
example; only, in place of being transverse, the groove is down-turned at its
extremities so as to assume a crescent shape; there is a well-marked vascular
foramen above it.

62 Professor Arthur Thomson

Andamanese (No. 1241, R.C.S.). In the transverse groove which replaces the
superior pair of spines there is a vascular foramen immediately above. The surface
for the attachment of the genio-hyoid muscles is elevated and tubercular.

Andaman (No. 1217, R.C.S.). Here there is a shallow depression with a
vascular foramen. ‘The lower slope of the fossa is rough for.the attachment of the
genio-hyoids. What is peculiar in this specimen is that the depression is situated
so high up on the surface of the bone. There are no spines.

From a consideration of the facts observed, it would seem that the
genial spines may be effaced and a hollow take their place. The way in
which this may occur is well illustrated in the specimens examined :— -

1. The area corresponding to the attachment of the genial muscles may
be smooth and free from spines. ‘This occurs in many examples,
though unfortunately no record was kept of the number of
instances in which it occurred.

2. The two superior genial spines may be replaced by two little pits,
as happens in the Guanche, No. 566, R.C.S., and the West Coast
African, No. 1241, R.C.S. In both these cases the inferior pair of
spines is represented by a central ridge or crest.

3. The two little pits may coalesce, so as to replace the superior pair of |
genial spines by what is variously described-as a shallow hollow,
fossa, dimple, pit, or depression. Or the hollow may be vertically
compressed, so as rather to be described as a transverse groove or
depression. Under these conditions the inferior genial spines may
be faintly marked, or represented by a rough tubercular area or
a rounded elevated field, the prominence of which depends on
the configuration of the lower symphysial border and the manner
of attachment of the mylo-hyoids and the anterior bellies of the
digastric muscles to what has been termed the digastric plate.

4. The rare cases which occur in which the hollow may be dignified
by the name of a “genial fossa,” the depression including the
whole area of the attachment of the genial muscles and being
limited inferiorly by the linear surface from which the mylo-
hyoids spring, which narrow bony attachment is interposed
between the area of origin of the genial muscles and that for
the attachment of the digastrics. As may be seen, the disposition
of this digastric surface is liable to considerable individual, and it
may be racial, variation.

A matter of some interest is revealed by a study of the sections of
the symphysis given on Plate I. From these it would appear that the
modelling of the posterior surface of the symphysial part of the mandible
stands in no constant relation to the form and contours of the anterior

On the Presence of Genial Tubercles on the Mandible of Man 63

aspect of this region ; for in all the cases figured in which a “ genial fossa ”
is present the characters of the mental prominence, which is so essentially
human, are still preserved, from which it may be concluded that the
disposition of the lower symphysial border is independent of, and not
associated with, the manner of attachment of the genial muscles.

Fig. 8, which represents what may be regarded as the more or less
typical arrangement of the muscles connected with this part of the

Fie. 8.

mandible, illustrates well how the attachment of the mylo-hyoid muscles,
which in the middle line becomes markedly fibrous, has a vertical linear
attachment as well as a horizontal union with the bone. The former may
often be recognised on the mandible as a vertical crest, which may extend
upwards towards the inferior genial spines, and downwards between the
area of attachment of the digastric muscles, forming occasionally in that
situation a prominent spine—a spine which in the anthropoids is often-
times well marked, and serves to emphasise in a very precise way the
attachment of the mylo-hyoid raphe to the central part of the posterior
edge of the digastric plate or simian ledge.

Morphologically we may regard the posterior surface of the symphysial

64 Professor Arthur Thomson

portion of the mandible as divisible into two parts: a part above the attach-
ment of the mylo-hyoids, which may conveniently be termed the buccal
area; and a part below, which may be called the basal part.

The buccal area is again subdivided into an upper or alveolar part, and
a lower or genial portion, from which the genial muscles arise. Obviously
the depth and disposition of the alveolar part will depend on the length
and setting of the roots of the incisor and canine teeth, the modelling of
this part of the bone being determined by the vertical position or varying
degree of splay of these teeth as met with in different types of jaw.

Fig. 9.

The basal part of the symphysis corresponds to that part of the bone
which lies below the level of the attachment of the mylo-hyoids and more
properly pertains to the region of the neck. Here are seen the surfaces
for the attachment of the digastrics.

If now we compare this region in man and the anthropoids, we see at
once that in the latter the alveolar part of the buccal area is stout and
thick, to provide accommodation for the long roots of the incisor teeth, as
well as for the enormous canines, the embedded portions of which sink
deeply into the substance of the bone, so that the bottoms of their alveoli
lie 6 or 7 mm. from the middle line and immediately above and to the
outer side of the genial fossa. It is this oblique disposition of the roots of
the canines which accounts for the great mass of the bone in this region.

a

Noe ae
pa ee ib

On the Presence of Genial Tubercles on the Mandible of Man 65

a

a In the apes, there being no reason for so stout a basal part as is met
__ with in man, owing to the great mass of the alveolar portion in those
animals, we find that the part of the bone which lies inferior to the mylo-

hyoid attachment becomes much diminished in size and is reduced to

the proportions of a relatively thin border, to the posterior edge of which
are attached the mylo-hyoids and the anterior bellies of the digastrics,

an arrangement which is well illustrated in the photograph of the mandible
of a female chimpanzee (fig. 9).

Fic. 10,

In this connexion it may not be amiss to draw attention to the
disposition and arrangement of these muscles in the ape as compared
with man.

In the anthropoids, owing to the smaller degree of erection of the head,
the anterior surface of the neck exposed is less than in man; consequently
the hyoid bone is tucked away within the angles of the jaw, and these

_ parts of the mandible, owing to the great proportionate development of

the rami, reach a relatively lower level than in-man. Consequently the
pull of the anterior bellies of the digastrics is more uniformly directed

_ backwards, and, it may be, even upwards, than in man, in whom, owing

to the greater range of extension of the head and neck, the pull of the
muscle in the extended position is not only backwards but downwards as

well—a circumstance which would explain the difference in the attach-
VOL. L. (THIRD SER. VOL. XI.)—OCT. 1915. 5

66 Professor Arthur Thomson

ment of the anterior bellies of the digastric muscles to the mandible in
these two groups, an explanation which will more readily be understood
by reference to the accompanying diagram (fig. 10).

It does not, therefore, seem unreasonable to suggest that the architecture
of this particular part of the ape’s jaw is the result of the different traction
effects of the digastrics and mylo-hyoids. In man, as has been seen, there
is a mechanical necessity for the provision of a stout basal symphysis;
whereas in the ape, owing to the great mass of the alveolar part of the
bone, this is no longer necessary.

Fic. 11,—Dissection of the submaxillary region in a young
male chimpanzee.

a, platysma; b, mandible; c, anterior belly of digastric, cut across;
r d, genial muscles ; e, lower border of body of mandible ; f, mylo-
hyoid muscle; g, submaxillary gland; h, anterior belly of digas-
tric, cut across; 7, hyoid bone; j, cervical fascia; k, platysma,
cut in the middle line and turned aside.
Unfortunately, the anthropoid material at my disposal is limited, but
I am here able to give a figure (fig. 11) of the appearance of the muscular
parts of the sub-maxillary region of a young male chimpanzee in my posses-
sion, wherein it will be seen that, though the digastrics are well developed,
their anterior bellies are broad and flattened, with a thinner bony attach-
ment than that which we see in man, in whom the section of the muscle
usually displays a more circular form and consequently spreads more
widely over the bony surface with which it is connected.
In this specimen it is also noteworthy that the mylo-hyoid muscle,
exposed by cutting away the greater part of the anterior belly of the left

On the Presence of Genial Tubercles on the Mandible of Man 67

digastric, is deficient in so far as the extent of its lateral attachment to
the mandible is concerned, and forms a sling reaching from the symphysis
to the hyoid bone, and having a free edge curving outwards and backwards
from the base of the symphysis underneath the sub-maxillary gland, where
its attachment to the mandible is concealed. By this arrangement the
under surface of the genial group of muscles is exposed, lying in part in
contact with the upper surface of the anterior belly of the digastric when
that muscle is replaced.

I have not been able to find any record of this arrangement; it most
closely resembles that cited by Macalister) in which account he describes

Fie. 12.— Milk dentition of an orang.

the mylo-hyoid as “almost completely absent and replaced by the anterior
belly of the digastric.”

The matter is of some interest, and deserving of further inquiry.

Hitherto our attention has been confined to the consideration of adult
specimens. If, however, we examine young examples, we will see still
further reasons for accounting for these differences between man and the
apes. ‘This stage is the more interesting because the growing jaw naturally
responds to the influence of the factors which subsequently determine its
form. Amongst these we must not overlook the fact that the bone has
to accommodate not only the milk teeth but also the dental sacs of the
permanent dentition. Fig. 12, which represents a dissection of the jaws of
an orang with the complete milk dentition and the sacs of the permanent

1 Trans. Roy. Irish Acad., vol. xxv., 1875, p. 34.

68 Professor Arthur Thomson

teeth displayed in situ, demonstrates how completely the mass of the fore
part of the mandible is occupied by these structures, the basal part of the
bone being represented by a mere shell.

A comparison with fig. 18, which is a representation of the human
mandible at the same period of growth, shows how in the human jaw the
space occupied by the dental structures is much less, and how, in con-
sequence, the basal part is better developed—a further proof, it would
seem, of how this part of the mandible must be reinforced by bone to give
it the necessary strength, a provision which accounts for the presence

Fie. 13.—Milk dentition in man.

of a mental prominence in varying degrees of development. The indi-
vidual variations of this basal part of the mandible in man will be
determined by the disposition and traction effects of the muscles attached
thereto, and will not, in my opinion, be due to any specialised functions of
these muscles, such as, has been suggested, are associated with speech.

The series of figures (fig. 14) here given are intended to illustrate how
by variations in the level of the attachment of the mylo-hyoid muscles to
the back of the symphysis differences in the form of the basal part of the
bone are induced. It will be noticed that in the highest specimen in the
figure the attachment of the mylo-hyoid (marked in black outline) reaches
a much lower level than that displayed in the lowest specimen; so that
whilst in the latter the basal part of the symphysis is of considerable
thickness, in the uppermost example the mesial attachment of the mylo-

—

On the Presence of Genial Tubercles on the Mandible of Man

Fic. 14,

69

70 Professor Arthur Thomson

hyoids coincides with the lower margin of the bone,-.and that in this view
little, if any, of the area for the attachment of the digastrics is shown, as
will be seen by a reference to Plate IL, top row: this is the specimen in which
we have a well-developed genial fossa, and here the bone exhibits a
tendency to form a prominent border which may be regarded as compar-
able to a rudimentary simian ledge. It would seem, therefore, that when
exceptionally we meet with this appearance in man, the necessity for the
deposition of bone around the area of attachment of the genial muscles no
longer exists, and we may have an arrangement comparable to that
exhibited in the apes, in whom advantage is taken of the angular hollow
formed by the union of the alveolar part of the bone with the simian ledge
to provide for the origin of the genial muscles; for, as has been already
pointed out, the tendency is for muscles to pit the bone when they are
attached to a concave surface, whilst if their origin be from a plane, or
convex surface, the usual arrangement is for their attachment to be
indicated by a spine or ridge. In fig. 15 the same features are exhibited,
as seen from below.

From this it would appear that the particular manner of attachment
of a muscle cannot be taken as any criterion of its functional activity.
Because, owing to the altered arrangement of the surrounding parts, we
find in some cases well-developed spines, whilst in other instances, owing
to different surrounding conditions, the spines are absent or replaced by
pits, these appearances are no justification for the assumption that the
presence of genial spines is an indication of any particular development of
the genio-glossi muscles in association with speech. The number of cases
quoted seems to place this contention beyond doubt.

There remains another aspect of the question to which reference must
be briefly made. Walkoff as the outcome of his examination of the
mandible of the anthropoids by the X-rays, laid great stress on the fact
that the photographs never exhibited the arrangement of the “trajectory ”
fibres associated with the attachment of the genial and digastric muscles
exhibited in man. He assumed, therefore, that this appearance in man
was directly concerned with the development of speech.

From what has been already stated it will be obvious that the arrange-
ment of the osseous fibres and lamelle will be determined primarily by the
general architecture of the bone, and that the arrangement of the fibres
and lamelle of the bone will only be a secondary effect of the strain of
the muscles.

If we can produce specimens from human beings, presumably as capable
of speaking their own language as their fellows, in which the particular

1 “ Menschenaffen : Studien iiber Entwickelung und Schidelbau,” Selenka, Band ii.

ee ae, ee

On the Presence of Genial Tubercles on the Mandible of Man

ESKIMO. Oxf. Univ. 855

BUSHMAN. R.C.S. 13001

FIGIAN. R-C.S. 1431.

NEW CALEDONIAN. £.C.5. mB.

Fic. 15.

72 Professor Arthur Thomson

arrangement of the “trajectory” fibres described by Walkoff is absent or
only present in very modified form, then the occurrence of such specimens
must prove fatal to that anatomist’s contention.

In order to verify this matter I asked my friend Dr R. H. Sankey to
take X-ray photographs of the five mandibles to which special reference
has been made in this paper. The results are shown in Plate II.; and, just
as one might expect when the conditions in the lower part of the
symphysial portion of the jaw resemble in their features those usually
characteristic of the ape, viz. the occurrence of a genial fossa and a
tendency towards the formation of a simian ledge, we find, as may be
seen, an almost complete absence of the “trajectory ” fibres usually revealed
in man, and an appearance closely resembling that figured by Walkoff of
this region in an orang, except in so far that the field in the ape is limited
by the enormous roots of the canines.

The specimens figured exhibit the varying appearances dependent on
the extension of the attachments of the digastrics and mylo-hyoids upwards
over the posterior surface of the bone, so increasing its thickness towards
the centre; and the arrangement of the fibres and lamelle displayed is due
to the altered fori thereby imparted to the mass of the bone, and not to
the individual detail of a particular group of “trajectory ” fibres necessarily
associated with any special function of the muscles attached thereto.

SUMMARY.

The assumption that the occurrence of genial spines in man is
necessarily associated with articulate speech is not justified by the facts :—

1. Because in many human mandibles the spines are frequently absent.

2. Because in numerous human jaws the spines are replaced by isolated
pits or depressions.

3. Because in rarer instances these pits may coalesce so as to form a
genial fossa corresponding to the area of attachment of the genial muscles.

4. Because there is no evidence to prove that the individuals to whom
such mandibles belonged were less capable of speech than their fellows.

5. It also appears that in man considerable variation may be met with’
in the level of the medial attachment of the mylo-hyoids to the back of
the symphysis, thereby giving rise to differences in the vertical length of
the “buccal” and “basal” portions of the bone on the posterior surface
of the symphysis.

6. In man, owing to the relatively small size of the incisor and canine
teeth, the alveolar part of the buccal portion of the jaw is feebly developed,
consequently the basal part must be stout to ensure the necessary strength.

On the Presence of Genial Tubercles on the Mandible of Man 73

Bushman. R.C.S., 1300.15. Eskimo, Oxf. Univ., 855.

Bushman. R.C.S., 1300.1.

Fijian. R.C.S., 1431. New Caledonian. R.C.S., 1118.

Piate II.

74 On the Presence of Genial Tubercles on the Mandible of Man

This accounts for the mental prominence and thick and rounded lower
border characteristic of modern man.

In the anthropoids, owing to the massing of the bone around the roots
of the large incisors and canines, the mandible is here stout and strong
and there is no need for a massive basal part. In the apes the basal part
is therefore merely represented by the simian ledge, which adds little to
the strength of the jaw, and serves primarily as a border to which the
mylo-hyoids and digastrics are attached.

7. In cases in man in which a genial fossa occurs, and in which owing
to the low attachment of the mylo-hyoids the basal part is reduced in
depth, the anterior part of the basal portion persists as the mental
prominence, whilst its posterior edge tends to be backdrawn by the
combined actions of the digastrics and mylo-hyoids, thus producing a
form suggestive of a rudimentary simian ledge.

8. Whilst emphasis has been laid on the arrangement in man of the
“trajectory” fibres of the genio-glossus and digastrics as a very char-
acteristic feature as compared with that displayed in the apes, it has
been shown that there need be no correlation between this arrangement
and the faculty of speech, since in the human jaw herein described, which
in its general form and architecture most resembles that of the ape, no
such characteristic appearance of the “trajectory ” fibres, on X-ray examina-
tion, was seen to exist.

9. From which it appears that the arrangement of the “ trajectory ” fibres —
does not depend on any particular function exercised by the genio-hyoid
muscles in connexion with the faculty of speech, but is determined by
the general architecture of the bone and the grouping and modelling of
its parts.

a a

ON THE FACTORS CONCERNED IN CAUSING ROTATION OF
THE INTESTINE IN MAN. By J. Ernest Frazer, F.R.CS.,
St Mary's Hospital, Professor of Anatomy in the University of
London ;.and R. H. Ropsins, M.D. Cantab., Senior Demonstrator of
Anatomy in the Medical School of St Mary’s Hospital.

Ir has been recognised for a very long time that the disposition of the
intestinal canal in the adult human subject is the result of a process of
rotation which it undergoes in the course of embryonic development, the

tube being changed from an early condition, in which it is described as

being straight and median in position, into one in which the distal part
is said to be rotated round the proximal portion in a direction from left
to right. Figures illustrating the nature and extent of this rotation are
common in all text-books of anatomy, and variations in the phenomenon
are constantly assumed to account for cases showing abnormal disposition
of the intestinal tube in some small or large part of its course. But one

does not meet with much success in an endeavour to obtain a clear and

detailed notion of the nature of the rotation and of the extent of gut
taking part in it. This is particularly the case when light is sought on
the origin and cause of the movement; in fact, we have not found any
satisfactory or coherent account of the process from this point of view
in the books we have consulted.

In the absence of reliable information, we have endeavoured to work
the question out for ourselves, and to build up a reasonable and connected
theory of cause and effect in association with the rotation of the bowel.
In the nature of things, any explanation of the changes which occur must
be theoretical, but we have, we hope, been successful in formulating a
coherent hypothesis which is in accordance with the facts that we have
directly observed. It is founded on the examination, by the microscope
and by reconstructions, of embryos from the fourth week to the third
month, and by dissection of specimens from this time up to birth: we
have made some eighteen models,’ large and smal], as well as other

1 These models were shown at the June meeting of the Anatomical Society. Figures
and separate accounts of each of the models would be a tedious addition to an already

long paper, and would serve no uscful purpose: we therefore have decided to dispense
with such formal descriptions. :

76 Professor J. Ernest Frazer and Dr R. H. Robbins

reconstructions, and propose to give in this paper the results of our study
of these and of our other specimens.

An example of the intestine placed in the median sagittal plane may
be taken from the embryo shown in fig. 1. The embryo is one of 5 mm.
in which a window has been cut in the left abdominal wall to expose the
intestinal tube: this, disposed in what is practically the middle line of the
cavity, forms a nearly right-angled V, the apex of which is continuous

vilelline
ven,

Fic. 1.—5-mm. embryo, simplified from models, showing belly cavity through window
in wall. Course of vitelline duct indicated by dotted lines on further side of cut
body stalk. Shows gut lying practically in median sagittal plane.

with the vitelline duct. The vitelline vein lies in the cavity in front of
the proximal limb of the V, running up to join the sub-hepatic anastomosis
above, and down to reach the vitelline duct externally. It is worth noting
that the hinder limb of the V is continuously curved, corresponding with
the umbilical arteries, on and between which it lies.

A great change must take place in the disposition of the intestines if
the adult state is to be attained from the simple conditions seen in this
embryo. We think it is convenient to divide this process of development
into three stages: the first of these extends to the period of return of the

Factors concerned in causing Rotation of the Intestine in Man 77

intestines to the abdominal cavity ; the second begins with this return and
lasts till the cecum comes into relation with the dorsal wall of the
abdomen ; while the third goes on from this until some time after birth.
Each of these stages has its special characters: the first stage is essentially
that of an umbilical loop with two limbs lying beside one another, the
second is the stage of rotation, in which the planes of the adult condition
are reached ; and the third exhibits the extension in those planes by which
the various parts of the tube attain their usual individual position.

bursa, Omenlalis
& slomach

lefl
a §=6mesongohros,

mesenlery
dati! loft body sal?
cole angle

Fic. 2.—8-mm. embryo. Simplified from model. Seen from the ventral side, and
rather from the left. V, continuous with the apex of the loop, contains not
only the epithelial remains of the vitelline duct, but also the vitelline artery,
cad: the vein which joins it just beyond the apex of the loop. The ‘‘ umbilical
cord” passed to the right of the tail: this, with the oblique view-point, gives the
appearance of the umbilical loop being directed to the right.

First STAGE.

Fig. 2, from an embryo of 8 mm., exhibits the essential points of the
first stage. There is a loop consisting of two limbs, proximal and distal,
lying in the umbilical sac; the sac is not shown, having been removed
with the front wall of the belly. The proximal limb is placed to the right
of the middle line, and, in the sac, to the right of the distal limb,

The presence of the loop in the umbilical sac seems to be the natural
result of its growth in a cavity too small or too much taken up to contain
it: the apex of the V in fig. 1 is held in the umbilical opening by the
attachment to it of the vitelline duct, and it is only to be expected that it

78 Professor J. Benast Frazer and Dr R. H. Robbins

will be guided, so to speak, by this duct into the opening when the
elongation of the loop occurs.

In a specimen of 7°5 mm., in which the proximal limb of the loop is
not turned over and depressed to the same degree as in the embryo from
which fig. 2 was drawn, but lies more on the level of the rounded ventral
surface of the mesentery, the concavity of the limb is occupied by the
continuation of the left umbilical vein on the visceral aspect of the liver,
with which is a small prolongation from the right lobe of that organ.
These structures that occupy the concavity are along the upper edge of
the umbilical opening. In the 8-mm. embryo, and to a greater degree

lefl umbilical
vein

Fic. 3.—Schemes to illustrate the effect of the vitello-umbilical anastomosis and descent
of the liver on the proximal limb of the loop, represented as on frontal section. In
the first figure the left umbilical vein passes up mainly to the left of the liver but is
also sending offshoots below it which join the vitelline system. In the second figure
this anastomosis forms now the main left umbilical drainage, and is carried down on
the visceral aspect of the liver, the hepatic end of the vein swinging in the direction
of the arrow. The result is that the proximal limb is folded over to the right.

in those of about 9 and 10 mm., the right lobe has very much increased
in size and the limb is correspondingly depressed, while the rounded
mesenteric surface, concave from above down, is in contact with the liver
tissue surrounding the venous channel. On the other hand, the umbilical
vein in the 5-mm. specimen passes up mainly to the left of the com-
paratively small liver, but anastomoses on the caudal aspect of the organ
with the vitelline system: the specimen is not in good enough condition
to permit closer examination of the nature of the vitelline anastomoses.
As a result of the study of the models of these embryos we suggest that
the turning over of the proximal limb of the loop to the right is directly
due to its close relation to the vein and liver. When the secondary left

Factors concerned in causing Rotation of the Intestine in Man 79

umbilical-vein is formed as the result of the vitello-umbilical junction,
the new venous channel lies on the visceral surface of the liver and is
earried with this across the ventral aspect of the proximal limb of the
loop of gut: the vein runs up from the left side of the umbilical opening
to the right lobe of the liver, and as this descends it carries down the
_ upper part of the vein, swinging it, as it were, on its lower umbilical end,
with the effect of turning the proximal limb over to the right. The
schemes in fig. 3 may perhaps make this plainer.

The loop in an early specimen, such as in fig. 2, is a freely movable
tongue-shaped projection, directed ventrally from a fixed base. The
mesentery of the loop is continuous with the median mesentery attached
to the dorsal abdominal wall, but in addition to this the two limbs of the
gut, where they become continuous with the upper and lower parts of
the rest of the tube, are relatively fixed by thick areas of mesentery.
These can now be considered under duodenal and colic headings
respectively.

(a) The Duodenal Fiaation.

If the proximal loop is looked at from the right, as diagrammatically
represented in fig. 4, it is seen to form a curved loop, concave ventrally,
placed beside the median mesentery. At its cranial end a thick pad is seen
on the dorsal surface of this end of the limb, standing out from the general
level of the median mesentery. The portion of the gut which is fastened
to the dorsal wall by this conglomeration of tissue is the future duodenum,
_ and the pad itself is the dorsal duodenal mesentery or mesoduodenum : its
substance is continuous on the left with that of the general mesentery,
extends up to the foramen of Winslow, and presents below a rounded blunt
falciform edge, deep to which a,shallow recess lies between it and the
median mesentery.

If a frontal section were to be made, running cranio-caudally through
the mesentery a little ventral to its dorsal attachment and passing through
the foramen of Winslow above (along the interrupted line in fig. 4), the
mesenteric structures, seen from the dorsal side, would present somewhat
the aspect which is schematically shown in fig. 5. In the first figure the
line of the median mesentery is seen to be interrupted above by the opening
into the lesser sac, and just below this the thick mass of the mesoduodenum
is apparent, standing out to the right and carrying the duodenum on its
ventral surface.

These figures are only schemes, but they are founded on the reconstruc-
tions of the parts: the thick hook-like arrangement of the mesoduodenum
is a striking feature in sections through the parts, and the hollow of

80 Professor J. Ernest Frazer and Dr R. H. Robbins

the hook, the little inter-mesenteric recess, is to be found throughout
the greater part of the first stage. It is in this mesoduodenum that the
pancreatic outgrowths occur and enlarge, the upper one passing below the
foramen of Winslow and so into the lower or right wall of the small sac,

— line of seelon

/

/
“Or of bj;
inesenlery Gis ¥ slow
— : Parl of liver

"ln sile.

SAace occupied

by liver
Coop on umbilical
median = SAC
hresenlery

4. duct &

Fie. 4.—Diagram of proximal limb of loop seen from the right. It shows the duodeno-
umbilical loop turned over to the right and depressed, so that it lies beside the
median mesentery. The ventral surface of the limb and the mesentery is in contact
with liver, which should occupy the space (black) between them and the belly wall.
The interrupted line gives the imaginary line of section for the schemes in fig, 5.
Cf. fig. 6, where part of the limb is cut away.

while the lower outgrowth enlarges rapidly in the mesoduodenum itself.
These are indicated in the schemes.

The formation of the duodenal curve has nothing to do directly with
the occurrence of rotation in the intestinal loop, but, as the lower end of
the duodenum affords a fixed point of attachment for the proximal limb
of the loop, a short account of its production, as it presents itself to us, may
not be out of place.

le i ew ee ed
as r ’

Factors concerned in causing Rotation of the Intestine in Man _ 81

— In the first scheme in fig. 5 the duodenum is seen on the further or
ventral side of the mesoduodenum, in which the head of the pancreas is
indicated ; the second drawing shows that this head has increased in size
and has curved out the intestinal tube, a process which has progressed still
further in the third figure, but the duodenum throughout is held by its
mesoduodenum. This account denotes shortly the manner in which we
believe the form of the duodenum to be attained—curved out to the right
by the growth of the head of the pancreas, and remaining fixed throughout
to its mesoduodenal base. The earlier growth of the head of the pancreas
appears to be mainly in its upper part, so that the proximal portion of the

Fic. 5.—Schemes to illustrate the formation of the curve of the duodenum. The mesentery is
supposed to be viewed from the dorsum, having been cut away from its dorsal attachment.
The dorsal mesoduodenum is seen as a thick mass projecting to the right immediately below
the protrusion to the left of the small sac. The alimentary tube is shown by interrupted lines
running down in the front wall of the small sac, turning to the right, and becoming con-
tinuous with the duodenum which passes down in front of the mesoduodenum. The head (H)
and body (B) of pancreas grow into the mesoduodenum: observe that B can pass almost
directly into the wall of the small sac. The other figures show how, while B extends into
this wall, H grows in the mesoduodenum and by its enlargement curves out the duodenum
round it: thus the duodenum is attached all the time to the mesoduodenum. X is the
position of Treitz’ band, put in its hypothetical place in the first two figures.

duodenum is raised and curved, then the middle and lower parts enlarge and
the corresponding portions of the tube are bowed out (see figs. 10 and 11).
It follows from this conception of the duodenum that the muscle of
Treitz is formed in the lower part of the mesoduodenum : its place is indi-
cated in the schemes, but we have not been able to discover undoubted
evidence of its presence before the 35-mm., stage, when the duodenal curve
is practically complete. It may be that the method of staining of our
specimens makes more difficult the recognition of the band before this time,
VOL. L. (THIRD SER. VOL, XI.)—OCT. 1915. 6

82 Professor J. Ernest Frazer and Dr R. H. Robbins

or perhaps its definite formation and recognition may be associated with
the increasing strain thrown on this part of the gut with the later down-
ward growth of the head of the pancreas.

We have no doubt that the duodenal formation comes about in the way out-
lined above. But we are not so certain about the terminal piece of this part of the
bowel, whether there might not be some secondary adhesion present here at a later
stage. For various reasons we are inclined against this view, but the question is of
little importance relative to our main object, so we do not propose to consider
it further.

The formation of the duodenal curve proceeds throughout the first
stage, progressing more rapidly in the latter part of the stage, like the
other modifications that occur in the simple conditions of the 8-mm. embryo.
The mode of formation, in relation with the visceral surface of the liver,
leads to the rectification of the originally oblique position (fig. 11) of the
duodenum, and it comes into a more nearly frontal plane behind this organ,
while its distal part must be directed inwards and must therefore form a
sharp duodeno-jejunal curve forward close against the right side of the
median mesentery (see fig. 10)

It is convenient here to distinguish between that part of the proximal
limb of the intestinal loop which extends in the abdomen from the duo-
denum to the umbilical opening, and that part which is in the umbilical
sac : the first can be referred to as the duodeno-umbilical loop and the other
as the umbilical part of the proximal limb.

The superior mesenteric artery passes downwards and forwards in the ~
mesentery to the left of the middle of the mesoduodenum to gain the
mesentery of the loop, and the band of Treitz is continuous with the con-
densation which surrounds the arterial stem.

(by The Colic Fixation.

The fixation of the base of the distal limb of the loop is simple, but has
not, we believe, been hitherto described. .The continuous curve of this
limb, as seen in fig. 2, is no longer visible in fig. 3 where the colon is seen
to be bent at a sharp angle which we may term the “colic angle”: this
angle, of course, marks the junction of the “midgut” with the “hindgut”
in the older descriptions. The appearance of this angle suggests that it is
produced by the attachment to the point of the angle of a band or other
structure which holds it up, but allows the loop to turn freely forward, and
examination of the specimens reveals at once the existence of such a band.

Its position can be understood from fig. 6, where the structures are —
viewed from the right: the greater part of the duodeno-umbilical loop is
cut away, exposing the median mesentery and the colic angle, while the cut

Factors concerned in causing Rotation of the Intestine in Man 83

edge of the mesentery is clearly visible. The position of the band, which
_ we term the “retention band,” is indicated by the interrupted lines: the
_ direction of the lines does not imply that any such direction of disposal is
_ to be made out, for in structure it is at this stage, of course, merely a band
_ of much condensed mesenchyme. ‘Traced towards the colic angle, the
_ greater and thickest part of the band leads to the point of the angle, but a
_ thinner part passes behind the angle to become continuous with the thick
_ mesocolon of the “hindgut,” and another thinner part runs in front of the
_ angle to the distal limb and reaches the dilation just in front of the angle
which marks the situation of the future cecum. Traced in the other

_ Fic. 6.—Diagram modified and simplified from models. 7°5 mm. Duodeno-umbilical loop cut
away largely, exposing the median mesentery, on which the position of the retention band is
marked by interrupted lines, C/. fig. 4. A, B, lines of sections a and 6, which, however,
are directly from sections through the model. In these sections the retention band
is stippled.

“a

- direction, the band joins the concentration round the mesenteric vessels into
which the band of Treitz has already been stated to pass. A section
_ through the situation A, just above the angle, shows the band as a marked
thickening in the median mesentery, while the mesenteric vessels are turned
over with the duodeno-umbilical loop and lie on its right side: a section
further back, at B, shows that the band is no longer in the mesocolic area
but is now merged in the thickened mesenchyme round the superior mesen-
teric vessels, in the axis of the common mesentery, where, though it may
be supposed to lie as shown in the figure, it is not distinctly marked off.

As stated above, the band presents on examination only the evidence of con-
densed mesenchyme in the early stages, with one or two minute vessels among the

84 Professor J. Ernest Frazer and Dr R. H. Robbins

cells ; in later stages nerves are distinctly visible with the vessels, and, as the band
gets smaller, actually or proportionately, the vessels and nerves become more
marked and the condensation has the appearance of being of secondary importance ©
to them. The obliquity of the band and its connexion with the band of Treitz
high up suggest the possibility that. they may be remains of a more extensive
structure which had some connexion with the more cranially-placed roof of the
widely open intestinal sac of early stages. Discussion of such an interesting
question would be outside our province, even if we possessed material young enough
and in sufficiently good preservation to enable us to speak from direct acquaintance
with the subject: as it is, we have no desire to make any suggestion concerning
its origin nor any wider statement about its distribution or possibilities.

But although we have no views to advance about the morphological
position of the retention band, concerning its practical effect on the colon
of the human embryo we do not think there can be any doubt. The
constant presence of the colic angle is enough, in our opinion, to justify
the presumption that traction is being exercised on that part of the gut,
and when this thick band is found in the exact situation that would be
suggested by a consideration of the angle, it seems to us that no further
evidence is required to permit us to describe the band as exercising such
traction. But when we use the word “traction” we do not mean to imply
an active approximation of the colic angle to the region of the duodenum ©
measurements on the models show us that the distance between them
remains the same nearly to the end of the first stage, so there is no actual
approximation. But the relative approximation is very great, as it is
hardly necessary to point out. The band holds the piéce of gut to which
it is attached in the same place while the body caudal to it is growing,
and for this reason we have termed it the retention band.

’ The value of the retention band is evident when we consider the great growth
of the post-umbilical segment of the body which occurs in the first stage. In this
growth the colic angle is held in place by the band, and consequently the ‘ hind-
gut” of the older descriptions must be drawn out between the angle and cloaca.
This is an interesting reflection when considered with von Berenberg-Gossler’s
hypothesis, founded on the examination of a very rare and striking teratological
specimen, that not only the rectum, but also the colon, caecum, and terminal part
of the ileum are derived from the cloacal walls. However this may be, we think
there is no doubt that the band, by holding the colic angle, relatively approximates
the angle and duodenum and at the same time draws out the gut distal to the
angle so that its length at any time is in correspondence with that of the post-
umbilical part of the belly.

We can now appreciate the condition of the complete intestinal and
mesenteric complex—from our point of view it may be simply pictured as
in the scheme in fig. 7. In the first of these schemes the whole system is
represented as flattened out, and it is possible to divide descriptively the
mesentery into that of the loop and that in the abdomen ; or, since the basal

Factors concerned in causing Rotation of the Intestine in Man 85

—_—

ah part of the loop remains in the abdomen, into that of the loop and that of

_ the remainder of the gut: this last part can be simply called the median

_ mesentery. The median mesentery has a part below the retention band
_ and a part above the band of Treitz: the upper part is continuous on its
_ right side with the mesoduodenum, and need not concern us further, but
_ the lower part, which has to do with the appearance of rotation of the
_ bowels, can be referred to when necessary as the median mesocolon.
____ In the loop the arterial axis can be taken as dividing the area of
_ mesentery into a proximal mesentery and a distal or mesocolon of the loop.
_ The retention band, then, can be described as separating the median
_ mesocolon from that of the loop.

So far, the loop with which we have dealt is characterised by the more
or less equal growth of its parts, so that its limbs are about of the same

Fic. 7.—Analytical schemes of the mesentery. A, at the beginning of the first stage. B,
teward the end of this stage. Observe that the narrow strip (mesocolon) between the
arterial axis and the distal limb remains unatfected, whereas the mesentery of the
proximal limb widens very considerably with the growth in length of the limb.

_ length and the depth of mesentery between them and the arterial axis is
- nearly equal on both sides, as appears in the scheme. But, as the first
stage goes on, modifications appear in these details, although the essential
features of the stage—the double-limbed loop, with the depressed proximal
limb to the right of the distal—remain until the return of the bowel to
the abdomen. The end-products of these modifications chiefly concern us
from our present standpoint, and we will deal with these later in some
detail, but it can be pointed out now that, so far as the loop is concerned,
the modification is in the direction of great and disproportionate growth of
the proximal limb and of its mesentery, so that coils are formed to the
right of the distal limb, which remains relatively very short and with only
a narrow strip of mesocolon between it and the artery. Such differences
might be expressed as in fig. 7, B.

Within the abdomen increase takes place in cranio-caudal length and

86 Professor J. Ernest Frazer and Dr R. H. Robbins

dorso-ventral depth of the median mesocolon commensurate with the
growth of the hinder part of the embryo. The growth is most marked in
the latter half of the second and beginning of third month, and the result.
is as shown in fig. 8, where the median mesocolon a little time before the

Genmtal
tvberde.

Fie, 8.—Sagittal section to left of middle line of abdomen in embryo of 35mm, Reconstruction.

Seen from the left. The coils are left in sitd in the opened umbilical sac. The abdominal colon
and mesocolon form a median septum extending dorso-ventrally and up to the liver and attach-
ment of omental bursa above. The small figures are tracings from sections through the model
showing the increase in size of the umbilical colon in the cecal region. The sections pass
through the colon at about the levels indicated by the arrows: the dotted surfaces are those of
the cut intestine, which include part of the ileum in one section, while the position of attach-
ment to mesocolon is indicated by dotted lines,

intestinal return is viewed from the left side. The abdominal colon lies in
relation with the ventral wall, and the mesocolon extends as a median
septum in the cavity between this and the dorsal wall.

The less extensive area of mesocolon in a 28-mm. embryo is shown in fig. 9,

and its small size in one of 22 mm. can be estimated from fig. 11, where, however,
the abdomen is viewed from the right. A 26-mm. model shows an intermediate

:

Factors concerned in causing Rotation of the Intestine in Man 87

“stage, so that the rapid increase may be said to begin between the 22-mm. and
26-mm. stages. The thin area of mesocolon between the retention band and the
thick pelvic mesentery (see fig. 7) appears to be enlarged and drawn out to supply
the increased surface: this assumption seems to be justified by an examination of
the distribution of the vessels of the part, indicated in fig. 8. The ascending
branch of the inferior mesenteric elongates with the growth, showing that the
corresponding length of gut is drawn out, the situation of the colic angle being
marked by a branch of the superior mesenteric which joins the other vessel here.

The colic angle is found in the intestinal tube up to a fairly late stage,
becoming gradually less well marked. This is in accordance with what
occurs in the parts of the retention band.” The originally thickest part of

duodeno-

ce ae Nass umbilita?
umbilital Sec, tooo

Fic. 9.—Model of 28-mm. embryo, seen from the left side. Stomach and bursa omentalis have
been cut away in part, exposing the median mesocolon: when in position they reach down as
far as the genital structures below the suprarenal body. The vitelline vein has also been
cut away.

this band, that which went to thé colic angle, becomes smaller and presum-
ably weaker as the mesocolon grows, about the end of the second month,
and in the stage represented in fig. 8 it is only to be found as a slight
thickening beside the branch of the artery which runs to the region of the
angle. The portion of the band which passed dorsal to the angle to reach
the thick pelvic mesocolon becomes attenuated in a similar way, and the
only part which presents any appearance of strength is that part which is
shown in fig. 7 passing to the cecal region: this seems to become more
developed as growth proceeds, and is drawn out along the growing distal
limb of the loop, being well marked in the 26-mm. specimen and easily
recognised in that of 35 mm. as a fairly thick but small band in the
mesocolon between the mesenteric vessels and the colon, as far as the excum.

In fig. 8 the stomach and bursa omentalis have been cut away at their
attachments to the median structures, They are suspended to the left side

88 Professor J. Ernest Frazer and Dr R. H. Robbins

of the mesocolon, and are shown partially cut away in fig. 9: when in position
in this model they reach the floor of the false pelvis. By the end of the
first stage they have become relatively smaller and are well overlapped by |
the liver in front and below, this organ coming into relation with the colon.
The duodeno-umbilical loop is placed on the right side of the mesocolon,
between it and the right lobe of the liver. This loop increases in length
also, forming a curve the lowest part of which rests on the pelvic brim,

Sas

Sot Se 2eQH

vabiical sac.

ventral wall
mesodvodenum <5 and ladder.

median
*nesocolon.

Fic. 10.—View of the abdominal and umbilical contents from the right. 35-mm, embryo, Observe
that the duodeno-umbilical loop is sharply kinked just beyond the duodenum to form the
duodeno-jejunal flexure, the course of the gut being indicated by interrupted lines. The
rounded elevation of the head of the pancreas is seen in front of the duodenal curve and below
the cut vitelline vein. The mesoduodenum is visible behind the duodenum and below the
foramen of Winslow. (Cf. fig. 8.

apparently depressed, as it grows, by the liver. The deep and sharply cut
markings on the liver are enough to show that this organ exercises a certain
amount of pressure on the structures with which it comes into contact, and
retains them in position.

The condition present on the right side toward the end of the first stage
is seen in fig. 10. In this figure the duodenal curve is represented round
the head of the pancreas, which is visible as a slight rounded prominence
within the curve. Just distal to the duodenum the duodeno-jejunal flexure

Factors concerned in causing Rotation of the Intestine in Man 89

is to be found: its position is evident in the figure, and the course of the
hidden piece of gut is indicated by the interrupted lines. The bend lies
against the median mesocolon, between it and the plane of the mesentery
of the proximal limb of the loop, and in the concavity made by the
continuity between these two (see fig. 15). The position, on the right, of
the plane of the mesentery of the proximal limb is probably the result of
the pancreatic growth: this portion of the mesentery of the loop is continued
at its base on to the front of the duodenum and the head of the pancreas,
and it is carried somewhat to the right by them as they grow, thus

a ver ys a ~»

SQL SSVI SN

median

MCSOCo/or . To en
Colon

Fic. 11.—View from right of abdominal contents of 22-mm. embryo, the liver being removed to
the middle line. Modified from model. The interrupted line shows the position of the
duodeno-jejunal bend lying against the median mesocolon. Structures are cut short at the
umbilical opening. Head of pancreas iS not apparent.

affording an opportunity to the flexure to turn up under it, between it and
the median mesocolon. ‘Ihe flexure itself may also come into existence as
an indirect result of the pancreatic growth with its consequent bending in
of the distal end of the duodenum. This, with the comparative narrowness
of the mesentery at the base of the loop (fig. 7, B), would lead to an upward
and inward turning of the next succeeding part of the gut.

A corollary to this position of the flexure would be the placing on its
right, potentially, of the mesenteric vessels, lying as they do in the upper
part of the mesentery of the proximal limb.

The flexure is apparent in the 22-mm, stage (fig. 11) and is also seen in the

20-mm. specimen. In the 28-mm. embryo it is represented by a slight kink in the
intestine below the duodenum.

90 Professor J. Ernest Frazer and Dr R. H. Robbins

Between the flexure and the umbilical opening the abdominal part of
the proximal limb is curved beside the mesocolon.. All these structures,
simple modifications of the duodeno- umbilical loop, lie, with their mesentery,
between the right lobe of the liver and the median mesentery.

Summing up, then, the conditions which hold in the abdomen at the
end of the first stage, we may say that there is a median septum, movable
on its dorsa] attachment and made by the median mesocolon and colon,
placed between the omental bursa and stomach on the left and duodeno-
umbilical coils on the right, and that it is separated by these structures
from the left and right lobes of the liver respectively. These conditions

Fic. 12,—Schemes to show (A) the position of the structures below and between the lobes of the
liver before the return of the bowel, and (B) the alteration caused by the return. The» median
septum, which is displaced to the left in B, is the median mesocolon, the colon being supposed
removed with the front part by the section, which is transverse,

are all the natural and inevitable results of growth occurring in the
positions assumed at the beginning of the stage (see fig. 2), and there is
no alteration in the essential character of the intra-abdominal conditions
seen at that period.

The abdominal conditions are represented schematically in fig. 12, A.

SECOND STAGE.

The second stage, that of the return to the abdomen, is also that in
which rotation occurs. The rotation is the effect of the return on the
loop itself and on the contents of the abdominal cavity into which it
passes: the intra-abdominal conditions have already been described, but
it remains to examine the state of the umbilical loop and the mode

Factors concerned in causing Rotation of the Intestine in Man 91

ea

1-cause of its return before we consider the result attained by this
enomenon.
To take the last of these first. Various suggestions have been made
to the responsible factor which may be at work in the reduction of
he herniated intestine. Without entering into a discussion of these, we
nay say at once that our observations lead us decidedly to favour the view
it the intestines are, to use Mall’s term, “sucked back ” into the abdomen:
can find no evidence of any traction directly exercised on the loop or
its mesentery, nor any reason to suppose that there can be any indirect
traction brought to bear on it.
The process of being “sucked back” is, of course, one in which, as a

result of relatively greater external pressure, the contents of the sac are

eally pushed back into the abdomen. This accords with what we know
f the conditions inside that cavity. Jackson has shown that after the
I-mm. stage the liver decreases in proportionate bulk, and, as the
__ abdominal cavity is growing larger—perhaps disproportionately—it follows
that there must be a fall in intra-abdominal tension: the effect of this
fall on the amniotic pressure need not be regarded practically, so that the
pressure exercised by the amniotic fluid on the umbilical sac which it
surrounds must be relatively increased. In our view, there must come a
time when the increasing pressure will force the intestine out of the sac
‘into the belly, and that this does not occur pari passé with the fall in
internal pressure may be due to resistance offered by the greater bulk of
the structures in the sac when compared with that in the passage: it
‘seems very probable that such enlargement would hinder the return, but
when once the resistance is overcome by the relatively increasing pressure
of the sac, there is nothing further to interfere with the movement, which
goes on rapidly to its termination. °

__ Such appears to us to be a reasonable view to take of the circumstances attend-
‘ing the reduction of the extruded gut, but in adopting such a theory there are
certain points which present themselves for consideration, and about which a few
remarks may not be out of place. Firstly, there is the question of the meaning
of reduction of liver mass. Judging from our own specimens, we think it must
be very difficult to base accurate estimations of the actual size of the liver on
microscopic sections and reconstructions made from them. In our experience,
however well prepared and apparently fresh the embryo may have been, there is
yet always more or less retraction of the organ. For example, in the embryo from
_____ which the model shown in fig. 9 was made, though the preservation and histological

condition appear to be very good, yet if one were to judge the state present from the
~ actual sections, the liver did not occupy the lower part of the abdominal cavity
_atall. But the model of the liver shows at once that this would be a most fallacious

__ view, for it carries on it the sharply cut markings of the structures with which it
: was in contact, and these can be read on it with absolute certainty: they show

92 Professor J. Ernest Frazer and Dr R. H. Robbins

conclusively that the organ was in contact with the Wolffian remains and guber-
naculum where these lie in the extreme caudal floor of the cavity, or false pelvis,
although no indication of such relation could be gathered from the sections directly.
The model gives one an idea of the extent to which the liver has contracted, and
the question arises whether, seeing how much or how little this contraction may
be in any individual liver, it is possible to compare and estimate the bulk of
livers of various stages with more than approximate accuracy.

We would suggest, from the study of our models, that more trustworthy
figures relating to the actual size of the liver might be obtained from casts of
the general abdominal cavity, but we have not ourselves taken up this investiga-
tion. By the expression “actual size” we mean the presumed size in the living
embryo.

But, whatever may prove to be the result of further research in this matter,
we suppose that there can be no doubt that the relative decrease of the liver can
be expressed in other terms as ‘decrease in the rate of growth,” and it is this
decrease in growth that leads to the fall in intra-abdominal pressure. But to say
that the pressure falls in the belly is not to say that a space occurs there. No
doubt some of the fall in pressure is met by the partial collapse of the belly wall,
which is also under amniotic pressure, and in this way a potential space is
provided which, when necessary, can be distended by the returned bowel: re-
construction favours the idea that the lower part of the wall is retracted before
the return of the intestine, but comparison with later conditions is difficult, as
allowance cannot be made for individual differences in the specimens. Even if
we allow this possibility, however, there is also some change in the liver to-be
accounted for: it fills the spare cavity before the return, as shown by the recon-
struction of the liver in the 35-mm. specimen, but after the return it is separated
from the false pelvis by the coils of intestine and has acquired a different set of
markings. A possible explanation of this and allied points has occurred to us as
a result of consideration of liver reconstructions.

It is plain, from the nature of the markings, that the retraction of the organ
about which we have already spoken as occurring in sectioned specimens has
taken place at the time of employment of the hardening and fixing agents, so
that there can be no-question of absolute decrease of liver substance, and the
difference between such a liver and its bulk before the retraction took place must
admit practically of expression in terms of loss of fluid. If this is so, the liver
before retraction, the living organ filling the cavity, contains more fluid, e.g. blood,
than afterwards: in other words, it fills the cavity, although its rate of growth
may be decreasing, by virtue of holding more fluid in its meshes, and in this way
has a potential power of retraction which comes into play whenever circumstances
allow it to retract by taking up some of the space it occupies and permitting it
to discharge some of this fluid from its bulk. Thus it will be seen that, although
we are doubtful of the value of reconstructions for showing the actual size and
form of the living organ, yet they may be taken as perhaps expressing more
accurately the potential differences in bulk of liver substance than would such
models if they were to show the actual size only.

A fruitful comparison, then, can be made between the retracted liver of the
first stage and that of the second stage. In the first, the retraction is effected —
not by loss or atrophy of liver substance but by loss of fluid from the whole mass,
and in the second the arrival of the intestines in the abdomen allows the fluid to
leave the organ, so that it retracts. Thus in some ways and with evident reserva-

\

\

Factors concerned in causing Rotation of the Intestine in Man 93

——

tions the liver might be compared with the lung in the pleural cavity—it is in a
condition of undue expansion, and, as soon as an opportunity is given to it, it
retracts towards its base of attachment. In this connexion it is interesting to
note that the opening out of the liver under reagents, and the general direction
_ of its visceral surface, is similar to that observed in the organ after the return of
the bowel to the abdomen.
We bring forward these suggestions as purely hypothetical explanations of the
points raised above, for with our material we have not been able to devise any
_ means of putting it definitely to the proof.

i Having provided hypothetically for the factors causing return and for
accommodation for the intestines in the abdomen, it is now necessary to
_ inquire into the act of return itself. As is admitted, the act is practically
_ sudden and complete, and we have offered above a more or less satisfactory
_ reason for the sudden and complete nature of the action following the com-
- mencement of the return.

It is not possible, we think, for the umbilical coils to return en masse:
the shape and size of the umbilical opening forbid this, and when we
remember that the edge of the central notch in the liver corresponds with
the upper and side margins of the opening, with which it is in close contact,
and that the abdominal recti are also in the immediate neighbourhood, the
sense of impossibility becomes a positive certainty. If, then, the coils do
not return en masse, there must be a movement of each limb into the
abdomen in continuity, each moving with its corresponding mesentery, and
it becomes necessary to decide whether these limbs return together or one
_ before the other. Considerations of the conditions found in the sac lead

us to believe that the distal limb returns after the proximal one.

In the umbilical sac the colon is seen (fig. 8) to be placed along the left
side of the collection of coils, in a more or less straight line. It is a narrow
_ tube when it enters the sac, but ‘just before it reaches the cecal region it
_ imereases markedly in diameter, and this enlargement is still further
- inereased by the ileum which runs into it at an acute angle: the outlines
of the gut in the figure do not show this difference very well, but the
tracings from sections of the model at the levels indicated give a better
notion of the increase in calibre. If, now, we think of the conditions
present in the sac when the external pressure is moving the contents into
the abdomen, it would seem certain that this shape of the colon must
operate against its passage through the narrow neck of the sac. For the
neck must be completely filled by a mass of mesentery and gut, pressed
together in its narrow confines, and under such circumstances the cecal
enlargement must be retained in the sac. It does not appear to us that
we can escape from this conclusion as a result of a theoretical consideration
of conditions inside the sac.

94 Professor J. Ernest Frazer and Dr R. H. Robbins

We have not been able, at the moment, to obtain a fresh specimen at
the proper stage of development on which we could verify this conclusion
experimentally, and, so far as we know, only one case (Mall’s) has been
reported in which the intestinal loop has been found in a state of partial
reduction: in this case, while the proximal limb of the loop was in the
abdomen, the cecum still lay in the umbilical sac. Here, therefore, we
have an experiment which bears out the view we have advocated and, so
far as it goes, confirms us in that view.

We may call attention here to another observation we have made which might
be perhaps of some importance in this connexion. A system of large inter-
communicating venous sinuses exists in the mesentery close to the caecum, becoming
noticeable toward the end of the second month and apparently increasing in size
‘after this. It is conceivable that venous return might be hindered at the neck of
the sac when the mesentery is engaged in it, that these sinuses would therefore be
distended, and that in this way further resistance to the passage of the caecum
through the neck would arise. This possibility has presented itself to us, but we
do not desire to lay any emphasis on it, for we think that the retention of the
cecum is a necessary consequence of facts which are open to observation and
there is no need to call in to its aid a factor which rests on an imagined condition.

We have not investigated the conditions in other mammals, so cannot speak
about any corresponding influences in them: we hope to be able to do so ona
future occasion.

Holding the view, then, that the caecum is retained to the last in the
sac, we must assume that the proximal limb of the loop returns in successive
lengths, slipping back rapidly with its mesentery into the belly. We can
now see that the condition of the mesentery shown in fig. 7, B, fits in with
the scheme of return. The mesentery of the proximal limb is deep enough
to permit its gut to lie in the abdomen though the distal limb remains in
the sac. On the other hand, the narrowness of the strip of umbilical meso-
colon which exists between the colon and the arterial axis entails the
necessity of the mesenteric vessels also remaining in the sac with the colon,
for practically they can only move with the distal limb.

We can now imagine the mechanism in motion under the conditions we
have described. The proximal limb and its mesentery slip back into the
abdomen, the more proximal part first and so on, and thus find themselves
entering that cavity to the right of the median mesocolon, which we have
described as forming a median septum with its abdominal colon. This
septum extends above to the central notch in the liver, out of which the
colon passes forward to reach the umbilical sac. The returning coils,
entering below the right lobe of the liver, will nll the lower part of the
abdomen: in so doing they push the median septum to the left and dorsally, ©
swinging it back on its dorsal attachment, so that the coils pass ventral to
it and thus come to lie below the left lobe of the liver, though separated

Factors concerned in causing Rotation of the Intestine in Man 95

from it in part by the stomach and omental bursa. The general idea of
these changes is illustrated in the scheme in fig. 12, B. At the same time,
as suggested above, there becomes possible a certain amount of retraction
of the liver, with raising and opening out of its visceral surface, so that
the coils can gather below it. The extension of coils to the left takes
place in front of the displaced wedian septum, comes into relation with the
bursa omentalis in front of this portion of the colon, and in front of the

Fic, 13.—Schemes to show how the returning proximal limb of the loop passes below the umbilical
colon and mesenteric vessels. Supposed to be transverse sections looked at from above.

bursa lies below the left lobe of the liver directly: it also reaches this lobe
beyond the colon and bursa and stomach.

Moreover, in passing to the left, the coils must necessarily go below the
level of the ventrally directed distal limb of the loop and of the mesenteric
vessels, as these run forward from the notch of the liver to the umbilical
opening: these structures can be described, then, as passing forward to the
opening above the mass of coils and their mesentery. This is shown in
fig. 13.

When the colon leaves the sac and enters the cavity of the abdomen, it
must lie, therefore, with the main vessels on the top of the mass of coils
and their mesentery. In considering this matter it seemed to us that the

96 Professor J. Ernest Frazer and Dr R. H. Robbins

comparative shortness of the umbilical colon—i.c. the distance between the
abdominal end of the distal limb and the cacum—compared with the
length of the mesentery of the coils of small intestine would bring the
cecum into position on the coils, not reaching as far as their ventral limits
but lying between them and the liver. We were therefore interested in
observing the conditions in specimens shortly after the return of the bowel,
and our theoretical expectations were borne out by what was found in
these. Fig. 14 gives illustrations of some of these specimens, with
descriptions of them, and the differences between them appear to us simply
to indicate that there is a certain amount of chance or individual variation

wy
WE wy
\
SD

MY

Fic. 14.—Two specimens of 45 mm., intestines exposed by raising the liver carefully and depressing
the pelvic parts: in A the liver is represented as divided transversely, and the drawing is
somewhat diagrammatic. In A the cecum lay as shown in a curved state on the coils a little
to the right of the middle, but in B it was more to the right, though still definitely resting on
the coils. St. is the stomach. The mesocolon of the loop is seen in A but not in B, The
overhanging projecting part of the omental bursa has been raised to show the coils, but the
left transverse colon is too deep to be shown in this way. ~Altogether five specimens of this
period were examined. Of the others, one of xbout 40 mm. was like A in its cecal relations,
another of 42 mm. resembled B, but in one of 39 mm. the cecum lay to the right of the coils:
in this case the whole mass of coils seemed to be carried more than is usual to the left, so that
the cecum was not much beyond the level of the duodenum although it lay to the right of
them, and the right lobe of the liver was perhaps larger than usual.

in the immediate effect on the returning colon of the influences under which
it comes when it enters the abdomen. The walls of the colon are thicker
than those of the small intestine at this stage, and its lumen smaller, so
that it would resist bending or kinking with greater power than the small
bowel, as a thick rubber tubing tends more to assume a straight direction
than thin tubing. So one would expect that the umbilical colon, when it
enters the abdomen, would naturally tend to come into line with the part

Factors concerned in causing Rotation of the Intestine in Man 97

a

-of the abdominal colon with which it is directly continuous, 7.¢., it would
be disposed to turn toward the right, as can be understood from fig. 13.
But such a movement would be hampered by its entanglement between the
liver and the intestinal coils, and to us the differences in the specimens in
fig. 14 are only individual differences in the arrest of the movement
toward the right.

The immediate result of the return of the colon, then, is that it lies on
the coils of small intestine, with the cecum wedged in from behind between
these coils and the liver. There does not appear to be any reason to
suppose that peristaltic movements take place at this time in the intestine,
but a cursory observation of the abdomen shows at once that there is at
any rate a rapid increase in mass of these coils, and the tendency of the
mass as a whole would be to keep at the full length of its mesentery,
Under these circumstances, it seems to us that there would be a constant
inclination to press the cecum back from between the growing coils and
the solid liver, so that it and the colon would come to lie where there is
more freedom from pressure, namely, over the smaller bulk of the neck of
the mass. Such a position is, of course, transverse to the long axis of the
mesenteric “neck” of the mass of coils: the disposition would be a con-
sequence of the backward move of the cecum from between the coils and
the liver, for as it is pressed back the colon behind it naturally comes into
line with the transversely directed piece of the abdominal colon immediately
succeeding it, the process going on until the originally umbilical colon is
placed from left to right across the root of the mesentery of the loop, with
the czecum pointing to the right. In this way we explain the change from
a position above the coils, with a more or less dorso-ventral direction, to
one transversely placed across the mesentery behind the coils.

In the 55-mm. embryo the cecum is in contact with the dorsal wall to
the right of the mesentery. It is not in any way attached to the wall, in
fact it hardly touches it, but it is behind the plane of the coils of small
intestine, and the attainment of this position can be taken as marking the
end of the second stage in the evolution of the human type.

Glancing back at the description we have given of the progress of the
change, as we conceive it, in this stage, we may say that the fall in intra-
abdominal tension leads to the return of the intestine, that this takes place
quickly but not en masse, that the positions of the descending colon and
left part of the transverse colon in their relations to the small intestine are
consequences of the first part of the return, and that the position in proper
plane of the remainder of the colon is a delayed consequence of the last
part of the return. That is to say, that the rotated state, even though the
final positions are not yet reached, has been attained in its essentials

VOL, L. (THIRD SER. VOL. XI.)—OCT. 1915. 7

98 Professor J. Ernest Frazer and Dr R. H. Robbins

during this stage, as a result of the return of the bowel from the umbilical
sac. It is fitting, therefore, that we should inquire at this stage into the
nature and extent of this rotation.

It has already been said that the rotation occurs in the loop and does
not involve the duodenal region nor that of the median abdominal colon, so
that the descending and left portion of the transverse colon are not con-
cerned in the twist, although they appear to be included in it. The
diagrams in fig. 15 may be of assistance in following out the process. In
the first diagram the conditions of the earlier part of the first stage are
represented, the loop having been cut away. In B the conditions at the
end of the first stage are shown: the duodenal curve has appeared, widen-
ing out the attachment of the mesentery of the loop toward the right, so
that the duodeno-jejunal bend is seen turned up to the left of the axis of
the mesentery of the loop, while the stomach lies to the left of the median
colon and mesocolon but separated from them by the thin-walled bursa
omentalis. C is the same as B, but the proximal limb of the loop is left in
position with its mesentery, only the distal limb being supposed to have
been removed with its mesocolon: it is evident that when the proximal
limb returns it must do so to the right of the median mesocolon. The
result of this return on the mesocolon is seen in D: the colon and the meso-
colon are pushed to the left and backwards, so that they would have the
coils of small intestine in front of them. If the position of the structures
at the bases of the limbs of the loop is noted, it can be seen that these do
not change their relations to each other during the second stage: in B the
proximal limb is cut through beyond the duodeno-jejunal flexure, whereas
in D the division goes through that part; but if this is allowed for, the
relative position of the bases of the two limbs is seen to be practically the
same after as before the return of the intestine. The lower end of the duo-
denum is below the colic angle: this is partly the persistence of the essential
conditions of the first stage, and partly the result of depression due to the
pancreatic growth, but no effect seems to be produced on its level by the
return or rotation of the loop. The section of the colon is supposed to be
made in the region of the colic angle, and this is seen to remain in position
although the gut distal to it is turned backwards and to the left.

As a matter of fact, the region of the earlier angle does not remain
absolutely central in position, but is carried a little to the left of the middle
line; but, as the end of the duodenum and the duodeno-jejunal bend are
carried with it in that direction, the relative positions of all these structures
are practically unchanged. The movement of this part of the colon towards
the left is probably to be explained as a part of the swinging of the
abdominal colon to that side (as can be understood from fig. 13), and may

Ad tiie a). x

ae ow) ee Se

Factors concerned in causing Rotation of the Intestine in Man 99

be_made possible by return of part of the umbilical colon from the sac :

there is nothing to hinder the return of the unenlarged colon from the sac,
only the cecum being held back as a result of its size. |

Thus it becomes apparent that there is no tendency to rotate on the
part of the colic angle: whatever movement takes place is not in the
direction of rotation round the loop, but is in the other direction toward
the left. This being so, there can be no movement of rotation affecting the
gut distal to the angle, and it can be seen in D (fig. 15) that there is no
actual twist of this portion of intestine, it being simply laid back from its
median attachment while the coils pass in front of it.

When the proximal limb enters the abdomen, the upper part of the
small intestine returns first. It is to be expected that this part, continuous
with the duodeno-jejunal flexure, will lie against the median mesocolon,
and the next succeeding part as it enters the abdomen will lie ventral to
the first part and rather to its right. So, in a general way, we might say
that the coils which lie deepest in the abdomen and more to the left, pushed
there by those which enter subsequently, might be expected to be those
that return first, i.c. the upper part of the bowel. This agrees with general
experience, and calls for no further study. These proximal coils, as they
pass to the left, carry with them their mesentery and vessels, and twist
these below the main vessels which we have seen (fig. 13) must remain in
the umbilical sac: this can be taken as an indication of rotation of this
part of the loop. But those coils which lie to the right of the middle line
do not exhibit any indication of rotation, using the relation of their vessels

_ to the main vascular stem as the test of its occurrence. So also when the

czcum reaches the abdomen and lies on the coils, those coils which are on
its right obtain their blood from the arterial stem on their left, and, judged
by this standard, have not yet “rotated.” The mesocolon containing the
main vessels can be seen in fig. 14, A, lying with the colon on the coils: it
was not visible in specimen B without disturbing the coils.

When the czecum passes to the right of the mesenteric neck of the mass
of coils, however, the fundamental adult arrangement of right and left
branches of the main vessels is attained, and the rotation is complete.
Looking at it in this way, and judging the rotation from its effect on the
branches of the mesenteric vessels, the process can be said to commence
with the first passage of coils to the left, and to end when the cecum
reaches the dorsal wall—in other words, the rotation continues throughout
the second stage of our description.

A complete twist of this sort, through half a circle, involves the whole
of the free loop. The base, as we have seen, is fixed, and just where the
movable joins the fixed part the amount of rotation is not so great, but

100 Professor J. Ernest Frazer and Dr R. H. Robbins

it rapidly passes from the state of the original to that of the acquired
condition.

Examination of the vessels indicates the area of rotation very clearly.
The models make plain that the relations between artery and vein in the
fixed region of duodenum, dorsal to the junction of vitelline and superior
mesenteric veins, are practically the same in the 8-mm. embryo as in the
adult body, but the relation between the vessels in the loop is reversed
during the second stage. Thus the rotation, judged by its results, is
confined to the loop and occurs only during the second stage.

A rotation of such sort is conveniently spoken of as occurring round
the arterial axis, but it must not be assumed that the main vessel actually
forms an axis round which the loop twists. If the account we have given
has been properly understood, it will be evident that, although the first
stage can be schematically represented with an arterial axis and the
completed second stage shows the reversed branches round this axis, yet
the intervening rotation takes place without reference to any fixed axis.
When the first coils go to the left they pass below the artery because it
is temporarily fixed above them, but they do so without turning on it
and as a result of their surrounding relations: in the last part of rotation
the cecum is carried to the right and brings the artery with it, so that
the “axis” is really swung to the right on the remaining coils and not
these to the left on the artery as an axis. The point is perhaps one of
minor importance, but it is necessary to understand it if one wishes to
have a clear comprehension of the process of rotation.

Before proceeding to the third stage in the evolution of intestinal
position, it may be as well to deal with certain structures which we have
mentioned in the foregoing account of the two first stages. The retention
band is shown in fig. 6 as comprising a main part extending to the angle,
and two subsidiary parts going to the cecum and pelvic mesocolon re-
spectively. The main part, as already stated, diminishes in thickness
toward the end of the second month and, at the time of return and rotation,
is quite an insignificant thickening in the mesocolon which would only
be noticed if looked for in the proper situation. We have not been able
to find any certain representative of it in the full-term foetus. The
descending subsidiary part also thins away as the median colon elongates,
and is present only as a slight condensation along the ascending branch
of the inferior mesenteric artery in the second stage. The cecal prolonga-
tion from the band, however, becomes better marked and thicker as the

first stage proceeds, so that it is present as a strong and prominent band

in the 26-mm. embryo and is well marked, though not so thick, in the
35-mm. specimen. We have no means of ascertaining what relation, if

cl iii ia

Factors concerned in causing Rotation of the Intestine in Man 101

——_

_ any, there may be between the presence of this band and the comparative
slowness in the growth of the distal limb of the loop, nor have we made
any investigation into its ultimate fate: we have not so far found definite
evidences of its existence at birth.’

The colic angle depends for its presence on the colic attachment of
the retention band, and, presumably in consequence of the atrophy of this
band, the angle is less marked toward the end of the second month and
is practically non-existent when the return of the bowel is due. Its
position, however, can be easily recognised from the fact that the left
branch of the middle colic artery reaches the gut here, or, for practical
purposes, it can be placed on the gut opposite the jejuno-mesocolie fold,
which represents nearly enough the narrow part of the neck of the
mesentery of the loop. Generally speaking, therefore, it may be said that
the descending colon and less than the left half of the transverse colon are
derived from the median abdominal colon, distal to the colic angle, while
the remainder of the transverse and the ascending colon come from the
distal limb of the loop. .

The vitelline duct loses its connexion with the intestine at an early
stage—in one of our embryos, however, labelled as 12°5 mm., the duct was
still continuous with the intestinal wall, although no definite epithelial
strand of connexion could be made dut. Keibel and Elze have reported
the connexion in an embryo of about the same size, and Thyng in one a ¥
little larger. hee -

The vitelline vein is to be found as a small channel subsequent to the!" vst
intestinal return; we cannot say definitely when it finally disappears. leon

The vitelline artery was present on the right side of the loop of|
intestine in all our specimens which were examined on this point. It
was still to be found connected with the mesentery, but in a very attenuated |
state, in the 28-mm. embryo, but not later than this.

The bursa omentalis lies as a thin-walled sac behind the stomach, and
between it and the median mesentery. It is only fixed by its “neck,” on
the left side of the common dorsal mesentery, opposite the opening (foramen
of Winslow), and lies free below this with the stomach developing, so to
speak, in its front wall (see figs. 5 and 8). In the first half of the second
month it begins to project ventrally between the stomach and median
colon, and by the end of this month it forms a definite irregularly folded
projection in this situation, as may be seen in the model in fig. 9, and in

1 We are indebted to Professor Wood Jones for a reference to a paper by Rost (Arch. f.
klwn. Chir., 1912) in which he describes bands of involuntary muscle fibre in relation with
the proximal part of the transverse colon and elsewhere. It is possible that these may

represent remains of the structures we have described, but we have not gone into the
matter and cannot speak definitely about it.

102 Professor J. Ernest Frazer and Dr R. H. Robbins

the diagrams in fig. 15. This hollow projection of the excessively thin-
walled sac is, of course, the early indication of the great omentum, and it
lies in close contact with the abdominal colon at the end of the first stage
(fig. 15, C) but is not attached to it in any way. When the coils enter the
abdomen the median colon is turned to the left as in fig. 15, D, and not
only raises the bursa and the stomach, but is also pushed back below the

Fic, 15.—Four diagrams to show the positions of the bases of the limbs of the loop before and after
the return of the bowel. The abdominal colon is shown as a median septum with its
mesocolon, deflected to the left (in D) after the return. The colon is supposed to be divided
at about the region of the colic angle, and the proximal limb in front of the duodeno-jejunal
bend in A and B, and through the bend in D. Observe how the pancreatic growth carries
the base of attachment of the mesentery of the loop out to the right, allowing room for the
flexure in its lower concavity, and making possible the relation of the vessels to the transverse
part of the duodenum.

bursa so that the great omentum comes to lie on its ventral face to some
extent, and here is in contact with the coils of small intestine. The small
intestine seems to be responsible for raising the bursa and stomach both
indirectly through the colon and directly by its own mass as it gathers on
the left side of the abdomen. The future left half of transverse colon and
splenic flexure are now invaginated to some extent into the omental bursa

Factors concerned in causing Rotation of the Intestine in Man 103

a
_

from below, but there is not, at the end of the second stage, any adhesion
between the structures. The further changes in this region belong to the
third stage of our description.

; The great omentwm comes into evidence along the whole length of
the bursa and thus extends to the right as far as the first part of the
duodenum: when the colon of the loop ends the second stage by swinging
across the neck of the mass of coils, its distal part comes into a relation
with this right extremity of the bursal projection which is comparable
with that of the abdominal gut with which it is continuous (see fig. 16).
At the end of the second stage the omental projection covers the front
_ of the left part of the transverse colon and the upper left coils, and is not
quite disposed as in fig. 14, where it has been raised to exhibit the coils.

THIRD STAGE.

The third stage is one of extension and fixation of the colon in the
plane it has reached at the end of the preceding stage. Thus it is not
really a stage concerned in the actual rotation of the loop and does not
call for a very detailed description here.

When the cxcum comes into relation with the dorsal wall it touches it
at or about—i.e. just above—the crest of the ilium, and just below the
lower end of the kidney. As already stated, we found this position attained
in the 55-mm. specimen, but it seems to us highly probable, when the
individual variations found are taken into account, that in some cases this
standard would be departed from to a considerable extent. The length of
the second stage miglit be shortened or, in some cases, lengthened.

We first found adhesion of the colon in its new position in an embryo
of 63mm. Fig. 16 is drawn from the 63-mm. specimen, the small intestine
of the loop having been removed with the greater part of its mesentery
to give an exposure of the colon. The (originally umbilical) colon, passing
transversely across the neck of the coil-mass, has been laid down against
the pancreas, duodenum, and inner part of the kidney, and its reversed
strip of mesocolon is also laid against the dorsal structures and stretches
between the colon and the arterial axis, as in the earlier stages.

The adhesion in the 63-mm. fcetus is in the region of the duodenum,
the cecum and intervening part being still free.

On the left side the colon and mesocolon lie free on the dorsal wall, but
they cover a larger area here than at the beginning of the second stage:
at that time the “descending colon” barely reaches the inner border of the
left kidney, but now it runs down the middle of that organ. The left
“transverse colon” is also at a somewhat higher level than in the second

104 Professor J. Ernest Frazer and Dr R. H. Robbins

stage: 2.¢., it more decidedly invaginates the lower and back wall of the
omental bursa and passes higher up behind the stomach.

Our meaning in describing this part of the colon as “invaginating” the bursa
may perhaps be better understood from a glance at fig. 17. This represents in a
schematic fashion what would be found in a longitudinal dorso-ventral section along
a line such as @ in figs. 13 and 16. The plane of mesocolon is seen applied to the
dorsal wall, with the transverse gut cut through at its upper end and the descending
colon divided below. The upper one is seen to be projecting into the bursal
sac, invaginating its lower wall and thus coming to lie behind and below the

Fic, 16.—Fcetus of 63 mm. in which the small intestine has been cut away. The
cecum is in contact with the dorsal wall, but not yet adherent, and the mesocolon
of the loop can be recognised, laid with the colon across the duodenum. The
‘*jejuno-mesocolic fold” is clearly seen, and, being practically opposite the old
colic angle (see fig. 15, D), can be taken as marking the base of the mesentery of
the loop. Proximal to this the colon has come secondarily into relation with the
omental bursa, in line with the left transverse colon.

stomach, Small intestine is indicated in front of the colic plane. The second
figure shows how, by elongation and fusion occurring at a much later period, the
definitive condition can be attained in this region.

It is unnecessary to go into the particulars of our findings in individual
specimens throughout the rest of foetal life; a good idea of the progress in
this stage can be obtained by observing the relative positions of the great
gut in a few foetuses of different ages, such as are combined in fig. 18.

In this figure the positions of the colons in various stages are marked

Factors concerned in causing Rotation of the Intestine: in Man 105

on a chart of the dorsal wall. No. 1 represents the gut at 45 mm.: it is
laid down on the dorsal wall and just reaches the inner edge of the kidney,
stretching its mesentery, a, to its full extent, while its cwcal end is shown
in interrupted lines to indicate that it is not in contact with the wall
behind. The condition at 63 mm. is shown in 2, where the mesocolon on
the left side is seen to be extended so that the gut rests on the left kidney,
while its upper part, in relation with the bursal sac, is represented in

Fic. 17.—The first figure is a schematic section down the left side of the abdomen, as along the
line a in fig. 16 or fig. 13, to show the relation of the upper part of the abdominal colon to the
omental bursa after it has been turned to the left. The abdominal mesocolon is cut at m,
and p is the body of the pancreas in the back wall of the bursa. The second figure shows
how the adult condition can be reached from this: the elongating mesocolon fuses with the
bursa to form the transverse mesocolon, below this it is fixed to the wall, and at its lower end
may be free more or less for the iliac colon.

interrupted lines: on the right side its cecal end is in contact with the
dorsal wall just above the iliac crest below the right kidney, and its
mesocolon, b, is reversed and laid down across the duodenum and on the
wall as shown. The arrow indicates approximately the position of the
one-time colic angle beyond which the mesocolon of the right side proper
extends. Nos. 3 and 4 are stages in foetuses of 125 mm. and 160 mm. respec-
tively: the peripheral extension is evident on the left, and to a less extent
on the right. The mesocolon exhibits some attachment in the duodenal

106 Professor J. Ernest Frazer and Dr R. H. Robbins

region in the 63-mm. stage and a little later the caecum is found to be
adherent, so that these parts are relatively fixed and the extension on the
right occurs slowly between them. No, 5 is the position of the caecum and
colon on the right in a full-term foetus; its position on the left practically
corresponds with 4 and is not shown. The great growth in length of the
ilio-pelvic colon in the later stages is not shown. The position of kidneys
and suprarenals is not quite as shown in the later stages, as these organs
assume a rather higher level, but this need not be regarded from our
present point of view.

Fic, 18,—Plan to show the position of the colon at different periods. For explanation see text.
The abdominal mesocolon is seen at a, and that of the loop at 4.

Looking at this series of positions at different ages, it is evidently to
be concluded that the whole colon is elongating, its left curve is increasing
to the left and upwards, and its right curve to the right and upwards,
though to a less extent, probably owing to the larger resistance of the
right lobe of the liver. The increasing curve of the colon is only possible
when there is a corresponding increasing breadth of mesocolic area. This
is simply seen on the left side, where the mesocolic sheet is fixed in the
middle line, and its increasing breadth or depth is only a continuation of
the process which forms the median septum in the growing abdomen of the
second stage. In the figure the added areas of mesocolon are shown by
the dotted lines. On the right side, however, the mesocolon is at first

_ Factors concerned in causing Rotation of the Intestine in Man 107

—

“free, and it is only after it has become fixed that it is necessary to have an
increasing mesocolic area to keep pace with the slowly increasing colic
eurve. The fixation of the structure takes place fairly soon: the mesocolon,
b, in the figure becomes adherent to the back wall shortly after the 63-mm.
stage, so that the mesocolic areas of the succeeding stages are added to it.
Thus we may say that the mesocolon of the loop differs from that of the
left side in that it does not broaden before the intestinal return and only
slowly and to a less extent after this has taken place.

So far, then, it may be said that a general progressive widening of the
right and left mesocolons goes on pari passi with the elongation of the
colon and the increase of its curves.

We have worked out some of the details of the process, and think that there is
some reason to believe that the widening of the mesocolon, at any rate on the right
side, is not directly dependent on the growth of the colon. It is not necessary,
however, to go into that point, and it will suffice to look on the two enlargements
as associated and more or less corresponding with each other.

As the two mesocolic areas widen they become adherent to the dorsal
structures. Without dwelling on certain local peculiarities, it may be
said that the mesocolon in a general way shows adhesion increasing from
the centre toward the periphery, so that there remains a broad strip of
free membrane between the gut and the adherent portion, and this strip
is necessarily that in which active increase must be going on at the
moment.

In this way the mesocolon becomes gradually fixed to the dorsal
structures, a fate which overtakes the gut itself when the growth of the
intervening strip ceases. In the case of the left upper colon the contact
and adhesion is with the wall of the omental bursa, and has already been
mentioned. :

It seems to us, then, that the activities which constitute the changes
seen in the third stage may be said to be confined to the colon and meso-
colon, the latter extending in its plane and fixing itself as it extends. It
follows from this view that there is no fixation of the mesentery of the
small intestine. In fig. 18, for example, the mesocolic area, b, is fixed
between the gut and the straight dotted line: to the left of this the
mesentery would hang free, so that the obliquely directed “attached border
of the mesentery ” is really the extreme left limit of the area of adhesion
of the mesocolon of the loop.

The cecum during fcetal life is very constant in its level, about the
erest of the ilium. As the liver recedes the colon above this is bowed out
to form the bend which is ultimately known as the hepatic flexure.

We have not carried our investigations into post-partum development,

108 Professor J. Ernest Frazer and Dr R. H. Robbins

and therefore have no suggestions to offer concerning the subsequent
shifting of any portion of the intestines.

SUMMARY.

The greater part of this paper is occupied by an account made up
mainly of descriptions of a large number of inter-connected observations,
and it would be almost impossible to bring these into the form of an
abstract or summary. We propose, therefore, to limit our remarks under
this heading to a statement of the main or large conclusions to which we
have come, passing over the many smaller matters which may be found
in the paper itself.

4 have divided the evolution of the adult type into three stages :—

. The stage in which an umbilical “hernia” of the bowel exists,
ieeliag from the condition of the “median” intestine to the time of return
to the abdomen.

2. The stage of return and rotation, occurring about the tenth week,
and lasting for a short but variable time, coming to an end when the
whole length of the colon is in its proper plane relative to the small
intestine.

3. The stage of extension of colon and its mesocolon in that plane,
lasting till after birth. This stage is not really one in the course of
rotation proper, for this is confined to the second stage, the first stage
being a preparation for it.

The essential character of the first stage is the presence of an umbilical
loop with its proximal limb lying to the right of the distal limb. The
position is brought about by the depression of the proximal limb as a
result of the enlargement and downgrowth of the liver carrying with it
the vitello-umbilical venous anastomosis on its visceral surface.

Towards the end of the first stage there is rapid growth of the prostiaes
limb and its mesentery, so that a mass of coils occupies the umbilical sae,
along the left side of which the distal limb, consisting in part of cecum
and a portion of colon, is placed without coils.

The second stage starts with the somewhat sudden return from the
umbilical sac to the abdomen. The return is due to the fall of intra-
abdominal pressure owing mainly to relative decrease in liver mass: thus
the extra-abdominal (intra-amniotic) pressure pushes back the contents of
the sac. The return is not en masse, but the proximal limb returns first
in continuity of length, the caecum being retained to the last in the sac
owing to its larger size compared with the colon immediately continuous
with it. The sudden and complete nature of the return may be due to
resistance to the movement at first holding the coils in the sac; the

Factors concerned in causing Rotation of the Intestine in Man 109

resistance would be owing to the size of the mass of mesentery just inside
the sac compared with that passing through its opening. As the intra-
abdominal tension is falling all the time, it seems probable that, when the
slight resistance is at last overcome, the return could go on to its end
without stop.

When the coils of the proximal limb return they must occupy the
lower part of the abdomen below the liver, and they pass first into the
cavity on the right of the intra-abdominal colon and mesocolon: these
form, at the end of the first stage, a median “septum” which extends in
the cavity from the liver above to the pelvis below. As the coils spread
out below the liver they pass to the left, pushing this septum before them
to the left and backwards, so that the colon and mesocolon lie against the
dorsal wall behind the coils. Moreover, in going to the left, the coils have
passed below the continuity of the abdominal colon with the part still
remaining in the umbilical sac, and also below the main mesenteric vessels
which also remain in the sac with the colon. Thus, when the cecum
returns with these vessels toward the end of the movement, it must lie
on top of the coils, between them and the liver. In this way the rotation
is partly accomplished, a large part of the small intestine having passed
to the left below the upper part of the colon.

The cecum, at first wedged in between the liver and the intestine, is
forced back from this position by the pressure of the growing mass of
coils, and thus comes to lie to the right of the mesentery of the coils and
behind them, with the rest of the originally umbilical colon placed trans-
versely across the mesenteric neck of the mass. This essentially completes
the rotation, brings the czecum against the back wall on the right side,
and closes the second stage.

Rotation is limited to the bowel which constitutes, with its mesentery,
the umbilical loop. It does not involve the duodenum, which is curved
out separately as a result of the growth of the head of the pancreas on its
left side. Nor does it include the abdominal colon, which with its meso-
colon makes the “septum” already mentioned: this colon is continuous
with the umbilical colon at the “colic angle” held up by the “retention
band” in the mesocolon. The position in the adult of the original colic
angle is rather to the left of the middle of the transverse colon, so that the
actual rotation of bowel may be said to affect only the intestine lying
between the duodeno-jejunal bend proximally and the left middle of the
transverse colon distally.

The third stage shows the occurrence of widening in the mesocolic areas
applied to the dorsal wall, in association with growth of the gut attached
to them: thus there is an increasing length and curve of intestine and

110 Factors concerned in causing Rotation of the Intestine in Man

width of mesocolon. As the mesocolic areas widen adhesion takes place:
in a general way it may be said that the fixation spreads peripherally,
following the enlarging curve of the gut. This process occurs, of course,
behind the plane of the coils of small intestine and does not influence the
amount or nature of the rotation. It goes on for some time after birth
and in its course the splenic and hepatic flexures are produced.

We may conclude this short summary of our main conclusions by
pointing out the great influence exercised by the liver in the production
of the final conditions. No doubt this organ, with the Wolffian bodies,
is largely responsible through its growth for the early entrance of the
gut into the umbilical sac, as well as for the depression and turning to
the right of the proximal limb of the loop. It occupies all the available
space in the abdominal cavity and holds the median visceral structures
in place up to the intestinal return. By a relative decrease in its rate of
growth it leads to the ultimate return of the loop, and it probably helps
to accommodate the returned coils by an actual decrease in its size. It lies
in contact centrally with the retention band and colon passing from this
region to the umbilicus, and in this way keeps the returning coils down
in the lower part of the cavity so that they pass to the left below the
colon and mesenteric vessels. And in the third stage the slowness of the
peripheral spreading of the colon and mesocolon is without doubt associated
with the gradual decrease of the relative size of the liver.

['t

JOURNAL OF ANATOMY AND
PHYSIOLOGY

ENDOCRANIAL CASTS AND BRAIN FORM: A CRITICISM OF
SOME RECENT SPECULATIONS. By J. Symineron, M_D.,
_F.RS., Professor of Anatomy, Queen’s University, Belfast.
: \

EaRzy in this year I published a Lecture’ in which were described the
results of an investigation made with the object of ascertaining the extent
to which the inner surface of the cranial wall is moulded upon the opposed
surface of the brain. In the course of this research a large number of
endocranial, endodural, arachnoid, and brain casts were prepared from
recent man. Duplicates of these casts have been presented to the Museums
of the Royal Colleges of Surgeons of England and Edinburgh, where they
are available for examination by those interested in this question.

For many years past paleontologists have made endocranial casts of
the skulls of extinct animals in order to demonstrate the size and general
form of the cranial cavity and also to gain an idea of the degree of cerebral
development. Such casts are frequently called “brain casts,” apparently
on the assumption that the form of the brain is practically identical with
that of the cranial cavity.

The degree of approximation of the cranial aspect of the brain to the
interior of the skull differs considerably amongst the various members of
the vertebrata, so that to call a cast of the cranial cavity a “brain cast”
may be very incorrect, since such a cast may differ considerably both in
size and form from the brain itself. The distinction between the terms
“endocranial” and “brain” casts must now be specially emphasised, as
several anatomists and palwontologists have within recent years used
endocranial casts of dried and sometimes fragmentary skulls of man on
which to base a description of the convolutionary pattern of his cerebral
cortex and of other features of his brain. It is obvious that if these
deductions rest upon a sound basis of observed facts this method opens up

1 The Sir John Struthers Lecture “On the Relation of the Inner Surface of the

Cranium to the Cranial Aspect of the Brain,” Edinburgh Medical Journal, February 1915.
VOL. L. (THIRD SER. VOL. XI.)—JAN. 1916. 8

112 Professor J. Symington

a very interesting line of research, by offering the prospect of important
additions to our knowledge of the evolution of the brain of prehistoric
man, and by yielding interesting particulars regarding the character of this
organ in recent but deceased men whose brains have perished, but whose
skulls are available for scientific study.

In this paper I propose to consider the evidence presented by Professors
Eug. Dubois, A. Froriep,? M. Boule and R. Anthony,? R. Anthony,‘ and
Elliot Smith® in support of statements they have made regarding the
brain in cases where they had the opportunity of studying endocranial
easts of skulls in which the cranial wall was more or less perfectly pre-
served, but its contents destroyed. In my Struthers Lecture will be found
a detailed account of the effect of the structures intervening between the
skull and the brain in producing differences or permitting harmony between
the shape of the inner surface of the skull and the outer surface of the
brain. A careful comparison of a number of endocranial casts and of the
corresponding brains is an essential preliminary task before attempting a
reconstruction of the brain of ancient man from endocranial casts of his
skull. In the course of this review I shall have occasion to consider how
far the results of such work have been utilised.

ENDOCRANIAL CAST OF PITHECANTHROPUS ERECTUS.

At the Fourth International Congress of Zoology, held in Cambridge in
August 1898, Professor E. Dubois gave a communication on “The Brain
Cast of Pithecanthropus erectus,” which was published the following year
in the Proceedings of the Congress. At the meeting he showed an endo-
cranial cast of the celebrated skull-cap he found during excavations in
Java in 1891-92. After directing attention to certain peculiarities in the
general shape of the cast, he gave the following description of the markings
of the cerebral fissures and convolutions which it presented :—

“In the frontal region of the hemispheres the convolutions are most

| “Remarks upon the Brain Cast of Pithecanthropus erectus,’ Proc. of the Fourth Inter-
national Congress of Zoology held in Cambridge in 1898.

2 “Ueber den Schaedel und andere Knochenreste des Botanikers Hugo v. Mohl,” Archiv
fiir Anthropologie, Bd. viii., 1909.

3 “T’Encéphale de homme fossile de la Chapelle-aux-Saints,” L’ Anthropologie, tome
xxii, 1911.

1 “‘T’Encéphale de homme fossile de la Quina,” Bulletin et Memoires de la Socrété
@ Anthropologie de Paris, 1913. (Communicated to the Society 18th July 1912).

5 “Preliminary Report on the Cranial Cast,” an appendix to a paper by C. Dawson
and A. Smith Woodward “On the Discovery of a Paleolithic Human Skull and Mandible
in a Flint-bearing Gravel overlying the Wealden (Hastings Bed) at Piltdown Common,
Fletching, Sussex,” The Quarterly Journal of the Geological Soctety, vol. lxix. pt. 1, March 1913.
(Communicated to the Society 18th December 1912.)

Endocranial Casts and Brain Form 113

perfectly distinct. Those on the left side are a little different from those on
the right side; the latter are, further, best preserved. For first orientation
the central and precentral fissures are easily identified. The intraparietal
fissure is only very partially distinct, but seeming to point to a relatively
large occipital lobe, an ape-like condition, undoubtedly consequent on
a relatively larger development of the sensory centres of the cortex in
contrast with smaller areas of association. In the neighbourhood of the
median part of this sulcus the brain is very flat.

“The most conspicuous feature is the second frontal fissure, as
clearly developed as in any human hemisphere, originating in the common
T-shaped form from a clearly distinct inferior precentral suleus and having
the shape of a reversed ©. The two segments of this fissure encircle the
two limbs of perfectly definite Y-shaped anterior branches of the fissura
Sylvii, the stem of which is about 1 cm. long.

“The second frontal sulcus is only very partially preserved on the left
side.

“On both sides a median frontal fissure is very marked.

“The first frontal fissure is interrupted in different places, a condition
common in the apes as well as in man.

“The important inferior frontal convolution has attained a fair develop-
ment. I found the area of its exposed superficies equal to half the average
area in twelve European hemispheres, but at least double that in the brain
of a large chimpanzee or an orang-utan. This seems to indicate that our
fossil being possessed already a certain amount of power of speech. The
pars triangularis is present in this convolution, as results from the presence
of two anterior branches of the Sylvian fissure. But the pars opercularis
has only a very rudimentary development” (p. 82).

Unfortunately, so far as I have been able to ascertain, no duplicates
of this cast have been issued and no photographs or drawings published,
although it is sixteen years since Dubois read his paper. Under these
circumstances it is impossible for me to examine the evidence on which
Dubois made such precise and definite statements regarding the convolu-
tions of the anterior part of the brain of Pithecanthropus. I understand
Dubois intends to publish a fuller report on his cast, but this long delay
is greatly to be regretted, as the specimen is unique and of the greatest
scientific value. An excellent ectocranial cast was made by Dubois soon
after his return from Java. It has been widely distributed, and a copy
of this cast was used by Professor Schwalbe in his elaborate “Studien
ueber Pithecanthropus erectus” in the Zeitschrift fiir Morphologie wnd
Anthropologie, Bd. 1, 1899.

114 Professor J. Symington

ENDOCRANIAL Cast oF Mout’s SKULL.

In 1906 Professor A. Froriep had the opportunity of examining the
skeleton of Hugo v. Mohl, a former Professor of Botany in the University
of Tuebingen. Mohl died in 1872, and his remains were exhumed about
thirty-four years later. The vaulted portion of the skull was found intact ;
it included the frontal bone down to the supraorbital prominences, and the
occipital to slightly below the grooves for the transverse sinuses. The
sphenoid and ethmoid were decayed, and also most of the lower part of
the occipital. The two temporals were preserved, except that the squamous
portions were somewhat damaged. The missing parts were reconstructed
and an endocranial cast made. It is evident from these facts that the part
of the cast exposed in the norma verticalis is natural, but that the norme
laterales are artificial over the anterior part of the temporal lobe, the orbital
surface of the frontal lobe, and the main stem of the Sylvian fissure.

So far as the number and general distribution of the digital impressions
are concerned, the cast does not show any peculiarity as compared with
those I have made from dissecting-room subjects and described in my
Struthers Lecture.

In Froriep’s article in the Archiv fiir Anthropologie he gave on
plate vii. five photographic reproductions of his endocranial cast, viz.
vertical, frontal, occipital, and right and left lateral views, and on plate
vill. similar photographs of a model of Mohl’s cerebral hemispheres.
The method by which this “Gehirnmodell” was prepared from the endo-
cranial cast and the results obtained are of interest. The endocranial
cast showed the ridges due to the meningeal vessels and the elevations
indicating the depressions on the bone caused by the Pacchionian bodies.
These were all removed, and the plaster was also cut away along the
middle line to mark the position occupied by the superior sagittal sinus
and on each side for the transverse sinus. Furrows were also cut in the
course of what Froriep considered to be depressions indicating the position
of a number of the principal cerebral fissures. In figs. 1 to 4 are
reproduced Froriep’s photographs of his cast viewed from the norma
verticalis and left norma lateralis before this procedure and after its
conversion into a brain model. Iam unable to satisfy myself either from
Froriep’s photographs of his endocranial cast, or, more important still,
from a duplicate of this cast which I have had the opportunity of
studying, of the existence of depressions of sufficient distinctness to
justify the mapping out of the fissures shown in figs. 2 and 4.

In the left norma lateralis the middle and inferior temporal convolutions
are as usual well marked: the superior temporal sulcus is possibly somewhat

Endocranial Casts and Brain Form 115

exaggerated in making the reconstruction; part of the posterior limb of
the Sylvian fissure is distinctly indicated, but its upturned posterior end,
as well as the ascending anterior branch of this fissure, are in my opinion
marked on the brain model without any satisfactory indication of their
existence on the endocranial cast.

Even if we accepted, which I certainly cannot, Froriep’s brain model
as accurately defining the course of the main fissures on Mohl’s brain, it is
instructive to ascertain what it teaches us with regard to the degree of

.

Fic. 1.— Norma verticalis of endocranial cast Fic, 2.—Norma verticalis of Gehirnmodell
of von Mohl’s skull (Froriep), (Froriep).

development of his convolutions. Mohl was a distinguished botanist and
one of a family of very talented brothers, and therefore we might reasonably
anticipate that his cerebral cortex would exhibit at least an average degree
of complexity. It is true that the results of the careful study of the brains
of a number of distinguished men have not, on the whole, proved that
their cerebral hemispheres possess a marked advance in the complexity of
the convolutionary pattern over ordinary individuals, but in Mohl’s case
the various views of the model of his brain would serve admirably as a
representation of the hemispheres of a seven or eight months’ fcetus. The
appearance of the central, precentral, superior and inferior frontal and
intraparietal fissures in Mohl’s “Gehirnmodell” suggest this early stage in

116 Professor J. Symington

their development. It is evident that Froriep can only have intended to
represent the course and position of the main fissures, the secondary ones
not being sufficiently definite to warrant their addition. Even, however,
with regard to the main fissures, his representation of their appearance
must be regarded merely as a simple diagrammatic view and not an exact
picture of the tortuous course they so often pursue. If from an endo-
cranial cast only the general directions of the main fissures can be
determined, and the secondary and even tertiary ones, which are essential
for an estimate of the degree of cerebral development, have to be omitted,
it is obvious that the evidence afforded by an endocranial cast is useless

Fic. 3.—Left norma lateralis of endocranial cast Fic. 4.—Left norma lateralis of Gehirnmodell
of von Mohl’s skull (Froriep). (Froriep).

in forming a reasonable estimate of whether or not the individual from
whose skull it was taken possessed a simple, an average, or a complex type
of convolutions. Froriep considers that Moh] had a richly convoluted
brain, and he bases this conclusion upon the fact that in the profile and
occipital views of the endocranial cast the main convolutions are not
simple, but are composed of a large number of small prominences.

As is readily seen on figs. 1 and 3, the prominences on this endocranial
east. due to the digital impressions are practically limited to the lower
part of the frontal, temporal, and occipital lobes. They are even less
marked than in several casts I have made from dissecting-room subjects,
and I have taken a cast of the occipital end of the skull of a native
Australian in which the digital impressions above the transverse sinus
are quite as numerous as in Mohl’s skull.

__ Endocranial Casts and Brain Form 117

dl

ENDOCRANIAL Cast or LA CHAPELLE SKULL.

Science is indebted to Professor Boule for a series of very valuable and
well-illustrated memoirs! on the La Chapelle skeleton and its associated
remains. This fossil man belongs to the Neanderthal race; the skull is
very large, and Boule estimates the cranial capacity as amounting to
1620 c.c., or distinctly above the average of modern civilised races. An
endocranial cast of this skull was studied by Boule and Anthony? with
the special object of endeavouring to form an estimate of the degree of
cerebral development. For purposes of comparison they obtained similar
easts of the anthropoid apes, of the Neanderthal skull-cap, and of various
races of modern man. A number of these casts were those prepared by
Broca in connexion with his classical researches on cranio-cerebral
topography. Their paper is illustrated by photographs of the endocranial
east of the La Chapelle skull viewed from various aspects. Duplicates of
this cast, with those of the outer aspect of the same skull, were made in the
Museum d'Histoire Naturelle, and a limited number issued to subscribers.
Through the kindness of Professor Thane I have had the opportunity of
studying both the ectocranial and endocranial casts.

_ Boule and Anthony admit that the traces of the convolutions left on
the inner surface of the cranial wall give only an approximate idea of their
real appearance, and they compare such traces to the view of a statue from
which one is not allowed to remove the veil. They also state that the
appearance of the convolutions when in sitw is liable to differ somewhat
from that seen on a brain which has been removed from its cavity and
preserved, and that such differences are liable to mislead an observer who
is not cautious and has only one cast under examination. They accordingly
attach special importance to the comparison of a number of endocranial
casts with one another.

It is evident that they had no sets of endocranial, endodural, arachnoid,
and brain casts prepared from bodies in which the brain had been properly
hardened in situ by means of formol so as to avoid any appreciable
shrinkage of the brain, nor indeed do they seem to have had suitably
preserved brains to compare with endocranial casts from corresponding
subjects. They write:

“Nous nous sommes surtout attaché a comparer l'objet de notre étude
aux moulages endocraniens dont nous disposions” (p. 130). But surely it is
much more important to compare a series of endocranial casts with the
corresponding brain casts or hardened brains. The real question to be

1 “T/homme fossile de la Chapelle-uux-Saints,” L’ Anthropologie, xx., 1909; and

Annales de Paleontologie, 1911-13.
2 Op. cit., p. 112.

118 Professor J. Symington

solved is, What do endocranial casts teach us regarding the brain? And the
mere comparison of endocranial casts one with another can yield no direct
evidence as to the degree of complexity of the convolutions of the corre-
sponding brains, however useful they may be in forming an estimate of the
general size and shape of the brain and in demonstrating variations in the
markings on the inner aspect of the cranial wall.

In the “ Introduction ” to their paper they say :

“Notre travail nous a conduits a cette conclusion que l’encéphale de
l'homme fossil de la Chapelle-aux-Saints présente un ensemble de caractéres
dinfériorité plus nombreux et plus marqués que l’encéphale de n’importe
quel Homme actuel. S’il est humain a la fois par son volume absolu et
par son volume relatif, il parait se rapprocher de celui des Anthropoides
par la plupart des détails de sa morphologie.”

The large size of the endocranial cast would certainly alone justify the
assumption that the brain was human, for it is nearly three times greater
than that of the largest anthropoid apes. It is necessary, however, to
examine some of the reasons advanced in support of their important
conclusion that the brain of the La Chapelle man possessed more numerous
and more important marks of inferiority than any modern race of men and
that these characters indicated an approach towards the anthropoids.
Boule and Anthony consider that the traces of the cerebral convolutions
which are found on the endocranial cast of the La Chapelle skull are fewer,
less complicated, and coarser than those on similar casts of modern man,
and they assume that such endocranial markings prove that the brain of
the La Chapelle man possessed a simple or low type of convolutions. I
cannot assent to either of these propositions, as I have failed to discover
any special peculiarities in the form and distribution of the digital
impressions on the endocranial cast as compared with those in modern
man. The number and depth of the digital impressions on recent skulls
are well known to vary considerably, and those of the La Chapelle fall well
within the normal range of variation. Further, my own observations upon
a considerable number of sets of endocranial and brain casts have satisfied
me that the degree of simplicity or complexity of the convolutions cannot
be accurately estimated from endocranial casts.

Boule and Anthony discuss at some length the peculiarities in the
position of the branches of the Sylvian fissure and of the insular opercula ~
as compared with modern inan and the apes. It would be useless to refer
to their comparative results, because in my opinion the data upon which
they are based are unsound. In attempting from their endocranial cast to
determine the position of the anterior branches of the Sylvian fissure and
the “cap” of Broca, or frontal operculum, they have made serious mistakes.

Endocranial Casts and Brain Form 119

The main grounds on which such an adverse opinion is expressed will be
evident from a comparison of figs. 5 and 6. Fig. 5, which is a diagram of
the right lateral aspect of the La Chapelle brain, is reproduced from
Boule and Anthony’s paper. Spa. and Spp. indicate the position of the
anterior and posterior pre-Sylvian fissures which form the anterior and
posterior boundaries of the frontal operculum. In fig. 6 is seen a photo-
graph of the right norma lateralis of the skull of a female sixty-one years
old, on which has been outlined the fissures of the corresponding portion of
the right hemisphere. The two anterior branches of her Sylvian fissure are

Fie. 5. —Diagram of right norma lateralis of endocranial cast of La Chapelle skull
; (Boule and Anthony).

seen to belong to the U-shaped type, and in this respect correspond to the
arrangement represented in fig. 5. Here, however, the resemblance
ceases. In the La Chapelle brain both branches appear to pass upwards
from the rounded margin separating the orbital and lateral surfaces of the
frontal lobe on to the lateral surface of the frontal lobe. Both fissures
ascend, and the posterior one is at the level of a coronal plane passing
through the anterior end of the temporal lobe. It is difficult to understand
how the “cap” of Broca in such a position could form an operculum to the
central lobe unless this lobe extended much further forward than is normal
in the adult human brain, or the forward growth of the temporal lobe
was defective. If such an arrangement of parts actually existed in the

120 Professor J. Symington

La Chapelle brain, it would form an interesting comparison with a fcetal
brain of about the seventh month (see fig. 275, Quain’s Anatomy, 11th
edition, vol. iii. pt. 1.).

The brain represented in fig. 6 shows the “cap” of Broca and its associated
Sylvian branches to be distinctly farther back, and this is undoubtedly the
usual position.

The lateral boundary of the orbital surface of an endocranial cast is

Fig. 6.—Photograph of the right norma lateralis of an endocranial cast of the
skull of a female sixty-one years old. On this is outlined the fissures of the
corresponding part of the brain. 4 nat. size.

c.f., central fissure ; r.p. of s f., posterior branch of Sylvian fissure; r.a.a., anterior ascend-

ing branch of Sylvian fissure. Inferior ascending branch not labelled; it lies below
P.T., P.T. (pars triangularis).

often marked by one or more grooves which may correspond to lateral
offshoots of the sulcus orbitalis on the orbital surface of the frontal lobe
of the brain. Boule and Anthony were evidently making a very doubtful
guess in representing these grooves as markings due to the pre-Sylvian
fissures. The rashness of their attempt to localise these fissures is
enhanced by the fact that in the reconstruction of the skull Boule was
unable, from the pieces of the skull found, to reconstruct the roof of the
right orbit and the anterior boundary of the right middle fossa of the
base of the skull, so that the endocranial cast does not show the actual

Endocranial Casts and Brain Form 121

form of the orbital surface of the frontal lobe or the anterior end of the
temporal lobe of the brain, these having been reconstructed.

Fig. 7 is a photograph of the endocranial cast of the La Chapelle skull
viewed from above. Upon this I have marked all the fissures represented
by Boule and Anthony in fig. 8 of their paper in L’Anthropologie, tome xxii.

Fic. 7.—Photograph of the norma verticalis of the endocranial cast of La
Chapelle skull on which is marked the position, according to Boule
and Anthony, of certain cerebral fissures. 4 nat. size,

P.O. F., parieto-occipital fissure ; C.F., upper part of central fissure ; 8.B., sinus
of Breschet ; R, area where cranial wall was defective.

The parieto-occipital are the only fissures whose entire course on this
aspect of the brain are depicted, only traces of a few other fissures being
shown, so that the convolutionary pattern on the vault is very incom-
pletely illustrated. In the case of the fissures that are marked, Boule
and Anthony appear to have assumed that any faint depression on the
endocranial cast would correspond to some fissure.

122 Professor J. Symington

If there is one point in cranio-cerebral topography that can readily be
demonstrated, it is that on the vault near the median plane the superior
cerebral veins, lacune laterales, superior sagittal sinus, Pacchionian bodies,
and the cerebrospinal fluid, which tends to accumulate in this position,
separate, in a number of places, the under surface of the skull from the
adjacent cortex, so that the cerebral fissures and convolutions leave no
markings on the endocranial cast of sufficient distinctness to enable one
to determine their position and extent.

I have endocranial casts of the vault of ten skulls, each with a cast of
the related part of the brain. My laboratory assistant, Miss Rea, has very
carefully transferred the outlines of the cerebral fissures on to the endo-
cranial casts. In no single instance do these fissures correspond to definite
depressions indicating their position, and very frequently, in various parts
of their course, they lie over eminences on the cast.

ENDOCRANIAL CAST OF THE PILTDOWN SKULL.

Fortunately it does not fall within the scope of this paper to give a
detailed account of the somewhat acrimonious discussion which accom-.
panied various attempts to reconstruct the Piltdown skull and to estimate
the form and capacity of its cranial cavity. It is, however, necessary to
mention some facts connected with that controversy which have a direct
bearing on the important question of the probable size and shape of the
brain of this primitive man.

In Dr Smith Woodward’s account of the first reconstruction of the
skull, published in March 1913, he gave the cranial capacity of the Piltdown
man as 1070 e.c. (see table of comparative measurements on p. 130 of his
paper in the Quarterly Journal of the Geological Society for March 1913),
but this estimate is modified in the text as follows :—

“The capacity of the brain case cannot, of course, be exactly determined ;
but measurements both by millet-seed and by water show that it must
have been at least 1070 c.c., while the reconstruction of the missing parts
suggests that it may have been a little more” (p. 126). On a duplicate
of an endocranial cast of the reconstructed skull made under Dr Smith
Woodward’s direction by Mr F. O. Barlow in 1912, and sold by Mr R. F.
Damon, I found the water displaced was nearly 100 c.c. more than the
amount given in the comparative table already mentioned. Apparently
as a result of a vigorous attack by Professor A. Keith in August 1913 on
the accuracy of this reconstruction, Dr Smith Woodward reconsidered the
question, and finally prepared a second one, the endocranial cast of which
has a capacity of almost exactly 1300 cec., or an increase of 230 c.c. as

Endocranial Casts and Brain Form 123

compared with his table of measurements, and about 130 cc. more than
the first cast. As the Piltdown cranial fragments represented less than
half of the entire cranial wall, and important parts on both sides of the
_ median plane were not found, it is obvious that it was impossible to make
more than an approximately accurate reconstruction, and anatomists will,
I believe, recognise the care and skill bestowed by Dr Smith Woodward,
Dr Pycraft, and Mr Barlow on this difficult piece of work. It is un-
fortunate that in the table of comparative measurements the Piltdown
skull is represented as possessing a lower cranial capacity than the
Gibraltar, Neanderthal, and a typical Australian skull, whereas on the
basis of the second reconstruction it is greater than any of these. It is
obvious that any estimate of the Piltdown brain must vary according to
the particular endocranial cast selected for examination.

Professor Elliot Smith’s “ Preliminary Report on the Cranial Cast” was
made in December 1912, and was based upon an examination of the endo-
cranial cast of Dr Smith Woodward’s first reconstruction. His opinion
does not appear, however, to have been materially modified by subsequent
criticisms of this cast, for in a communication to the Geological Society of
‘London more than two years later (in April 1914), he wrote as follows :—

_ “On the present occasion it is not my intention to say anything further
in. reference to the brain of Hoanthropus (because I am preparing a full
report upon it for presentation to the Royal Society); but, as there has
been considerable criticism of the restoration of the brain case, I should
like to take this opportunity of expressing my opinion that none of the
criticism has affected the accuracy of the preliminary note upon the cranial
east which I communicated to this Society in December 1912 (p. 93).

“ As the correct restoration of the cranium was the necessary preliminary
to any detailed study of the form of the brain, Dr Smith Woodward kindly
permitted me to examine the fragments of the skull, and make an inde-
pendent investigation with the view of determining what positions they
originally occupied in the skull. This examination revealed a multitude
of structural features which indicate precisely the true position and
orientation of each of the fragments; and there is no doubt that the
reconstruction of the skull which Dr Smith Woodward exhibited to the
Geological Society in December 1912 was a much closer approximation
to the truth than any of the various models so far exhibited in public
by his critics.”

The full report thus referred to was communicated to the Royal Society
on the 19th December 1914, but no account of it has up to the present been
published either in its Proceedings or Transactions. As Elliot Smith still
adheres to the views he expressed in 1912 on the Piltdown brain, and as there

124 Professor J. Symington

appears to be but little prospect of the early appearance of his full report
on this question, | must base any criticisms I have now to make on the
very brief and condensed statement contained in his “ Appendix.” In
this he wrote :—

“ At first sight the brain presents a considerable resemblance to the
well-known Paleolithic brain casts, and especially to those obtained from
the Gibraltar and La Quina remains, which are supposed to be women’s.
Like these casts, this one is relatively long, narrow, and especially flat; but
it is smaller, and presents more primitive features than any known human
brain or cranial cast ” (p. 146).

I have already emphasised the importance of distinguishing between
“endocranial” and “ brain” casts, and the paragraph just quoted shows the
confusion that may result from such lax terminology. It may seem
unnecessary to point out that no one has hitherto been fortunate enough
to obtain casts of the brain of Paleolithic man, although a number of more
or less perfect endocranial casts have been made.

The question of the capacity of the Piltdown cranial cavity has already
been considered, and it must surely be admitted that the assertion that it
is smaller than any known human brain or cranial cast was premature
and cannot now be maintained. ;

The further claim advanced by Elliot Smith that the Piltdown
endocranial cast presents “more primitive features than any known
human brain or cranial cast” necessarily requires a more detailed examina-
tion. The primitive features mentioned by Elliot Smith to which I propose
to refer are the simplicity of the cerebral sulci and of the associated con-
volutionary pattern, and certain peculiarities in the development of the
temporal and parietal lobes of the brain.

With reference to the cerebral sulci and convolutions we now give two
quotations from his preliminary report :—

“In this note I do not propose to discuss the significance of the faint
glimmerings which this cast affords of the pattern of the convolutions,
except to remark that there are indications sufficiently definite to enable us
to blot out a great part of the singularly primitive arrangement of sulci ”
(p. 146), and “unfortunately there are only very slight indications of the
arrangements of the furrows upon the surface of the cerebral hemispheres.
Nevertheless many of them can be detected, if not by sight, by passing the
finger over the surface and locating the depressions by touch. These
features are represented (with considerable exaggeration so far as depth is
concerned) in the diagram (fig. 11) on the preceding page” (p. 146).

It is evident from these extracts that Elliot Smith found that the
depressions and elevations on the endocranial cast, which apparently

Endocranial Casts and Brain Form 125

corresponded to the cerebral convolutions and fissures, were very indis-
tinctly marked, and he assumed from the “faint glimmerings” of the
convolutions on the cast that the Piltdown man possessed a brain with
“a singularly primitive arrangement of sulci.” I have reproduced his
sketch (fig. 8), which, although diagrammatic, illustrates admirably those
features which he regards as of special significance. It will be noticed
that none of the furrows which he has represented on the cast are named
or described. More cautious than Froriep, or Boule and Anthony, he does
not attempt to define the course and extent of even the main fissures, and

Sinus lateralis
Fic. 8.—Left norma lateralis of the internal cast of the skull from Piltdown
(Elliot Smith).

although letters are scattered with profusion over his diagram, not one
cerebral fissure or convolution is named. The letters s, n, k, v, and o.a. are
said to be placed on “ recognisable sulci,” but further details are not given,
except that they circumscribe an elevated area of the parietal lobe.

I need not repeat the details of the researches recorded in my Struthers
Lecture regarding the relations between endocranial and brain casts, and
will content myself with saying that the evidence furnished by the
markings on the cranial aspect of the Piltdown bone fragments do not
justify the statement that the Piltdown man had a singularly primitive
arrangement of the cerebri sulci, and this dictum can only, at the most,
be regarded as a plausible hypothesis.

126 Professor J. Symington

The next feature of the Piltdown brain to be considered is the temporal
lobe. This is described by Elliot Smith as follows :—

“One of the most striking features of this brain cast is the deep ex-
cavation of the temporal area, to form the wide bay between the inferior
temporal pole and the cerebellum. This is due to the marked attenuation
of the temporal region; but as we have already seen in the case of the
parietal region, so also here are definite signs that the expansion has begun
which eventually will transform this area into the very different configura-
tion that it presents in the modern brain. There is a very prominent
elliptical swelling; the summit (at T) is raised more than a centimetre
above the level of the surrounding cortex. It is 2 centimetres in vertical
measurement, and almost 3 centimetres long. This peculiar configuration
assumes quite a special interest when it is remembered that this obviously
expanding area occupies the position where, in the modern human brain,
is developed the territory which recent clinical research leads us to associate
with the power of spontaneous elaboration of speech and the ability to
recall names (Adolf Meyer).

“The configuration of the anterior part of the temporal area is also
peculiar, though a suggestion of the same kind of form is seen in the
Gibraltar brain cast. Below the point marked / the surface slopes inwards
towards the mesial plane, so that the fulness of the temporal pole of the
modern brain is wanting” (p. 147).

The deep excavation referred to above is a characteristic feature of all
human endocranial casts. It is due mainly to the upward projection of
the petrous portion of the temporal bone, but is completed behind by the
groove for the descending portion of the transverse sinus and in front by
the great wing of the sphenoid. Smith Woodward describes the left
temporal bone of the Piltdown skull as “typically human in every detail,”
and with this statement I am in agreement. The only peculiarity of
the bone, and this it shares with the other cranial fragments, is its great
thickness. The thickness does not affect, except to a slight extent, the
form of the cranial cavity. I have made several endocranial casts of this
region on the skulls of modern man, in which the general shape and dimen-
sions of this excavation are practically identical with those of Smith
Woodward’s endocranial cast of the Piltdown man. It must be remembered
that no part of the sphenoid bone of the Piltdown skull was found, and
therefore the exact configuration of the anterior part of the middle temporal
fossa of the base of the skull cannot be ascertained.

The descent of the floor of the middle fossa of the base of the skull
in the Piltdown man was supposed by Elliot Smith to be so marked that
he describes a curiously pendant portion of the temporal lobe of the brain

ie
oe
—

Endocranial Casts and Brain Form 127

which “he names “Polus temporalis inferior, to distinguish it from the
temporal pole of the modern man’s brain.” On comparing Smith
Woodward's two endocranial casts I find that in the second reconstruction

_ this descent is represented as less marked than in the first. In any case

it is not based upon an actual cast of this part of the skull, but on a
restoration of the sphenoid bone, as the most dependent part of the middle
fossa is formed by this bone. On any ordinary endocranial cast a promin-
ence is seen in this position which might be designated a Polus temporalis
imferior, if one desired to increase the number of poles of the cerebral
hemispheres.

The inward slope of the anterior part of the lateral aspect of the
temporal lobe of the brain is not peculiar to the Piltdown man. It isa
normal character of the brain of modern man (see fig. 9), and I doubt if it
were more marked in the Piltdown brain.

There still remains to be noted the eminence on the lateral aspect of
the temporal lobe (see dotted line surrounding letter T on fig. 8), to which
Elliot Smith appears to attach special importance in connexion with the
evolution of the speech centres. This eminence apparently corresponds
to a digital impression situated partly on the squamous part of the
temporal bone and partly on the adjacent lower portion of the parietal
bone. The bevelled upper border of the squamosa has obviously been
destroyed, and even on the cranial aspect the two bones do not quite meet,
so that in the work of reconstruction this space had to be filled up. This
elevation is therefore not entirely an actual cast of the bone fragments,
but is partly dependent on the way in which the interval between the
two bones is made good, and this would to some extent depend on the angle
at which they are set against one another. Although Elliot Smith gives
the dimension of this eminence, he does not associate it with any particular
convolution, or explain how the “obviously expanding” area of this
primitive brain differs from the same region in modern man.

In my Struthers Lecture I directed attention to the variations in the
appearance of this region in endocranial casts and showed that prominences
indicating the position of the middle and inferior temporal convolutions
were of constant occurrence, while the position of the superior temporal
convolution often corresponded to a smooth depression on the cast. If the
Piltdown endocranial cast be compared with those of modern men in which
the brains have been preserved, it will readily be seen that the eminence
T corresponds to one of the digital impressions due to the middle temporal
convolution. The lateral aspect of this convolution is normally broader
and projects farther out than either the superior or inferior temporal
convolution, and the greatest transverse diameter of an endocranial cast

VOL. L. (THIRD SER. VOL. XI.)—JAN. 1916. 9

128 Professor J. Symington

is always on an elevated area corresponding to the middle temporal con-
volution and placed above and generally slightly in front of the external
auditory meatus. I think there can be no reasonable doubt but that Smith
Woodward’s endocranial casts are both correct so far as the general

Fic, 9.—Photograph of an endocranial cast of a skull from the New
Hebrides, viewed from the front. Note the prominence on the
lateral aspect of the temporal lobe and the way in which the surface
slopes inwards towards the temporal pole.

position of the elevation marked T in Elliot Smith’s figure is concerned,
but in the first reconstruction the degree to which it projects laterally as
compared with the parietal area is certainly exaggerated.

After a careful study of Smith Woodward’s endocranial casts of the
Piltdown skull and their comparison with similar casts of modern men
in whom the brain was preserved, I have come to the conclusion that the

if

hiss

Endocranial Casts and Brain Form 129

Piltdown cranial fragments afford no satisfactory evidence in support
of the view that any special part of the temporal lobe was either im-
perfectly or precociously developed.

Elliot Smith also describes the parietal regions and writes :—

“T have already referred to the diminution and flattening of the frontal

_and parietal regions. In the centre of the latter there is an area, which
is well circumscribed by recognisable sulci (s, n, k, v, and o.a.), raised up

into a low hillock, the summit of which is at point marked P. It is more
pronounced on the right hemisphere. This indication of the expansion
of an area, the large dimensions and fulness of which are especially
characteristic of the human brain, is peculiarly significant, when taken
in conjunction with a similar condition in the temporal region ” (p. 146).
With reference to the diminution in the parietal region, he states that
while the maximum breadth of the hemisphere, which is at T, amounts
to 130 mm., “at the point P in the parietal region, corresponding to the
place where anthropometrists measure the breadth of the brain case, it
is only 102 mm.” If I understand Elliot Smith correctly, he considers

that at the area P the brain, although still imperfectly developed, showed

at this low hillock the beginnings of an expansion by which this part of
the brain would ultimately attain the large size characteristic of modern
man.

It is unnecessary to discuss seriously the evidence in favour of the
slight development of this part of the Piltdown brain, because it is based
upon the first reconstruction, and Smith Woodward in his second recon-
struction has considerably broadened the endocranial cast, increasing the
transverse diameter at the level of P by about 15 mm. and making the
general form of the upper part of the cerebral hemispheres readily
comparable with many existing races.

GENERAL SUMMARY.

It will have been noticed that Dubois, Boule and Anthony, and Elliot
Smith have all endeavoured to show from endocranial casts of certain
prehistoric skulls that the corresponding brains were of a “primitive”
type. Thus Dubois,! in describing the endocranial cast of Pithecanthropus
erectus, writes :—

“The intraparietal fissure is only very partially distinct, but seeming
to point to a relatively large occipital lobe, an ape-like condition, un-
doubtedly consequent on a relatively larger development of the sensory
centres of the cortex in contrast with smaller areas of association.”

1 Op. ctt., p. 112.

130 Endocranial Casts and Brain Form

Boule and Anthony,! in the case of the La Chapelle man, assert that:

“Si le volume relativement considérable de son encéphale constitue un
argument en faveur de son intelligence, l’aspect grossier de toutes les
circonvolutions visible parait au contraire, indiquer des facultés intellectuelles
rudimentaires ” (p. 193).

Elliot Smith,? more decided, writes with regard to the Piltdown brain :—

“Taking all its features into consideration, we must regard this as
being the most primitive and most simian brain so far recorded” (p. 147);
while Smith Woodward,? in a more popular account of this prehistoric
man, says :—

“So far.as they can be distinguished, the convolutions of the brain are
simpler than those of modern man and there are certain parts which remain
scarcely more developed than they are in a modern child” (p. 14).

In opposition to these views I venture to assert

1. That the simplicity or complexity of the cerebral fissures and
convolutions cannot be determined with any degree of accuracy from
endocranial casts, even on complete skulls, much less on reconstructions
from imperfect skulls. s

2. That it is not possible to estimate, even approximately, from the _
La Chapelle or Piltdown endocranial cast, the relative degree of development
of the various sensory and association centres in the cortex.

3. That the various deductions made by Boule, Anthony, Elliot Smith,
and others, with reference to the primitive and simian features of the
brains of certain prehistoric men, from an examination of their endoeranial
casts, are highly speculative and fallacious.

1 Op. cit., p. 112. 2 Op. ctt., p. 112.

3A Guide to the Fossil Remains of Man in the Department of Geology and Palzxontology
in the British Musewm, 1915.

THE ARTERIES OF THE PONS AND MEDULLA OBLONGATA.’ By
J.S. B. Sroprorp, M.D., Lecturer in Anatomy, University of Manchester.

INTRODUCTION,

THIs investigation was the outcome of an inquiry, made about two years
ago, to determine the precise distribution of the bulbar branches of the
_posterior inferior cerebellar artery.

At first it was intended to work out the exact areas of the hind brain —

supplied by the individual arteries, by injecting them in a similar manner
to that adopted by Beevor (20) in the case of the cerebral arteries; but it
soon became apparent that the variation in origin, course, and distribution
of the vessels of the hind brain made it an essential part of the work to
study also the gross anatomy of these arteries in a large number of brains.

Although the circle of Willis has been repeatedly studied (Windle,
Fawcett, etc.) during. recent years, little attention has been directed to
the exact course and relations of the vertebral and basilar arteries with
their branches. No text-book or monograph gives sufficient data, even
about the limits of the vertebral artery, and no attempt appears to have
been made to determine the percentage occurrence of the common varia-
tions in the course of this vessel, or the accurate arrangement of its
branches. Even Duret (55), whose work is quoted in references to the
blood supply of the bulb and pons, made only twenty injections, and did
not determine the modification in the position and size of the areas
supplied by the various vessels, which is dependent to a considerable
extent upon the slight variations that occur so frequently in their course.
Obviously, if this work is to be of any clinical value in localising the
position of arterial obstruction, it is essential to determine not only the
more usual areas supplied by the vessels but also the variations.

Furthermore, as this part of the work progressed, it became manifest
that the variation in the relationship between the arteries and cranial
nerves was of considerable clinical importance, and, as this branch of the
work has not previously been attempted, I shall have to consider it more
fully in a later part of the thesis.

! This thesis was submitted for the degree of M.D. at Manchester, in May 1915, and
awarded the Gold Medal.

132 Dr J. S. B. Stopford

Consequently, it has been found necessary to divide the investigation
into three parts :—

1. The gross anatomy of the vessels of the hind brain, with special

reference to their bulbar branches and relation to cranial nerves.
In this section, also, the arrangements of the vessels forming the

circle of Willis in the 150 brains examined will be briefly stated.

2. The precise areas of the medulla oblongata and pons supplied by the
individual arteries and their branches,

3. The clinical significance of the two former sections, illustrated, as far
as possible, by cases.

SouRCcE OF MATERIAL, ACKNOWLEDGMENTS, ETC.

Professor G. Elliot Smith has kindly permitted me to make full use of
all the material in his department, and I take this opportunity of express-
ing my heartiest thanks to him both for placing everything possible at my
disposal and for his advice, assistance, and constant interest in the work.

The fresh material used for the injection experiments has been obtained
from the Pathological Department of the Manchester Royal Infirmary, and
I am indebted to Professor A. E. Boycott and Dr W. B. Anderton for their ~
kindness in permitting me to procure such a large number of fresh brains.

For the opportunity of examining and taking notes on the anatomy of
the vessels in a number of cases of insanity I desire to thank the Medical
Officers of the Prestwich County Asylum.

The photographs used to illustrate the text were reproduced by Mr
Gooding, histologist to the Anatomical Department, either from my
sketches or the actual specimens. The sketches illustrating Part II.
were made directly from the Weigert-stained sections of the hind brain
which are the property of the Anatomical Department.

PART I.
THE GROSS ANATOMY OF THE VESSELS AT THE BASE OF THE BRAIN.

A.—THOSE IN RELATION TO THE HIND BRAIN.

The introductory statement explains the necessity for this section.
Unless the gross anatomy be considered, no reason for the marked variation
in the areas supplied by the individual arteries can be deduced, on account
of the lack of accurate information and the disregard by previous observers
of the factors which influence this variation in distribution. In addition,
it is essential for clinical application to determine the percentage wherever

The Arteries of the Pons and Medulla Oblongata 133

possible. This was indicated by Gowers (64), who appreciated the fact
that variation in the course of the larger trunks entailed a corresponding
variation in the origin of the nutrient arteries, and cited this as an explana-
tion of the different clinical pictures which may become manifest as a
result of occlusion of one of these trunks. The vessels of 150 brains
have been examined, and the series is composed as follows :—

77 from the Pathological Department,
40 from the Dissecting Room,
33 from Prestwich Asylum.

The basal trunks in the latter series show proportionately more
anomalies and variations than those of the other two, as suggested by
Berkley (22).

No artery has been considered in Parts I. and II. which showed any
obvious divergence from the normal as a result of arterio-sclerosis, or other
pathological condition of either the vessel or neighbouring structures.

Measurements have been avoided, wherever possible, as the object of
Part I. is primarily to elucidate the difficulties of the succeeding one,
and to introduce the practical and clinical application of this work, an
object which can only be achieved by denoting the various levels in
relation to fixed and established points on the hind brain.

In the percentages, decimals have been omitted, and the results in all
cases given to the nearest whole number.

The Vertebral Artery.

After piercing the dura and arachnoid, between the posterior arch of
the atlas and the occipital bone, this vessel lies between the most caudal
rootlets of the hypoglossal and the uppermost fibres of origin of the first
cervical nerve. At this level it is in relation to the lateral aspect of the
junction of spinal cord and medulla oblongata, and immediately anterior
to the spinal root of the accessory, as that nerve ascends to join its bulbar
part. The artery at once turns upwards to pass through the foramen
magnum, and, since it also inclines antero-medially as it ascends, comes to
lie anterior to the medulla and origin of the hypoglossal nerve. It usually
meets the vessel of the opposite side in the region of the antero-median
fissure at the lower border of the pons, where the two fuse at an acute
angle to form the basilar. During this course the artery is situated in the
cisterna cerebello-medullaris, and is only separated from the basi-occipital
by the two membranes it has penetrated.

Size.—There was almost constantly an inequality in size of the arteries
of the two sides (92 per cent.). The left was found to be larger in 51 per

134 Dr J. S. B. Stopford

cent. and the right in 41 per cent., the two being of equal calibre in only
8 per cent. In 20 per cent. the discrepancy in size was slight, but in the
rest (72 per cent.) the difference was marked, and in twenty-two the vessel
of one side was at least twice as large as that of the other.

The left was approximately twice the size of the right in 1 case.

i “i three times __,, @ 2 cases.

3 3 four ,, P- i > ee

; six » g >: eta

ne 3 eight _,, ; “ : eer
The right was approximately twice the size of the left in 1 case.

; o three times __,, z 4 cases.

is four 4 e - 3

is PS six > 7 » 1 case.

; ee eight _,, a : ee

ve =~ twenty ,, z Fi j ee

The right vertebral was excessively small in five cases, and both were
minute in one case; Blackburn (25) found the right abnormally small in
9 per cent., the left in 5 per cent., and both in 1 per cent.

It is generally admitted that the left is the larger, and Table 1. gives the

results of the various observers who have investigated this point.

The great variation in the figures is probably due to the fact that many
have considered “equal” those cases in which the difference in size on the
two sides was only slight.

TABLE I. +
| Size.
ee Number
| Observer, eainiand: -
| Left Larger. | Right Larger. | Equal.
per cent. per cent. per cent.
| Ehrman (56). d ; 57 16 14 70
Mori (99) . ee 35 20 2 78
Loewenfeld (92) . : : 61 39 51 10
Davy (48) . : : 2 98 27 8 65
| Longo (90). . F ‘ 50 6 6 88
| STOPFORD . : : . 150 51 41 8

Lewis (160) carefully measured the diameter of the vertebral artery
on the two sides, in the brains of 45 lunatics, and found the average on the
left to be 3°42 mm., and on the right 3:147 mm. It is curious that practi-

jane bia a ¢
Sey eae

The Arteries of the Pons and Medulla Oblongata — 135

cally no attention has been paid to the varying calibre of the individual

vessel of either side, since so many have investigated the comparative size
of the two. The present research has shown that there may be a very
marked reduction in size at three points in that part of the course of the
vessel which is under consideration. In fully half the cases there was a
distinct diminution in diameter immediately after the vessel had pierced
the dura; a second narrowing was to be found at the upper limit of its
course above the origin of the anterior spinal, where the lumen was usually
smaller than anywhere. The third point of notable reduction in size about
midway between the other two was rare, being only found four times on
each side, but is clinically of equal importance as a possible site of an
embolus ; and in this connexion it is of interest to note that the point of
reduction in calibre in two of these four cases marked the level of the
origin of the posterior inferior cerebellar artery, which in each case was
unusually large and almost equal in size to the vertebral.

Site of Junction to form the Basilar—Without exception, the modern
text-books describe the lowest limit of the basilar as the lower border of
the pons, and Spalteholz (126) alone gives some indication that the level ~
of the termination of the vertebral arteries may vary, by stating that the
posterior margin of the pons is “approximately” the site of the forma-
tion of the basilar. In older treatises on anatomy opinion is more divided
with regard to the upper limit of the vertebral arteries; Ruysch (117)
pictures the lower limit of the basilar as some distance above the lower
border of the pons, and Bourgery (159) as slightly below, whilst Willis
(155), Vicq d’Azyr (147), and several others represent it approximately
at the lower border.

Weber (151) quotes a case fs union of the vertebral arteries at a lower
level than normal.

In this series the vertebral arteries were found to fuse at the lower
border of the pons in 48 per cent., above that point in 20 per cent., and
below in 32 per cent. As the variation, above or below, was slight in a
number of cases, and was proved not to affect the distribution as it does
when more considerable variation exists, it may be said that the junction
was approximately at the lower border of pons in 73 per cent., above in
8 per cent., and below in 19 per cent. It was never found higher than a
third of an inch above the more usual site; but below, it was found as far
caudally as the level of the lower extremity of the olivary eminence in
one case, and the mid-olivary region in five others.

Anomalies.—_In two instances the right vertebral divided into two
trunks for the greater part of its intracranial course :—

In No. 20 (fig. 1), immediately after piercing the dura mater, the

136 Dr J. S. B. Stopford

vessel bifurcated into equal branches which united again a quarter of an
inch below the pons, so that an aperture fully one inch long was formed
which transmitted all the rootlets of the right hypoglossal nerve.

In No. 114 (fig. 1) the right vertebral exhibited duplication between
similar limits, but in this case the lateral division was larger than the
medial, and both parts were anterior to the superficial origin of the
XIIth nerve.

It is curious that such an extremely rare anomaly should occur twice
in this series. Tarenetzky (136) recorded one case precisely similar to

Basilar.
4+ Basilar.
Ant. inf. cerebell. 4
Vertebral. Post. inf. cerebell.
% ik
Transmitted Vertebral
hypoglossal nerve.

No. 20. No. 114.

“Vertebral.
— Foramen.

- Posterior inferior
cerebellar artery.

No. 97. No. 141.

Fic. 1.—Anomalies of vertebral and basilar arteries.

No. 20; and Kadyi has reported another in which the vertebral divided
into two before piercing the dura: one trunk followed the normal course
and united with the other branch (which entered the spinal canal with
the second cervical nerve) within the cranium.

Ogle (103) described a case where one of the roots of the left hypo-
glossal nerve completely pierced the wall of a normal left vertebral; and
Anderson (6) has given an account of duplication in the lower part of the
neck below the level of the third cervical vertebra.

The only other anomaly was found in No. 97, where a minute foramen
(sufficiently large to admit a probe) was seen penetrating the centre of
the left vertebral just above the origin of the posterior inferior cerebellar

~ n -
SK ee

The Arteries of the Pons and Medulla Oblongata 137

artery. A similar condition has been described by Blackburn (25) in the
case of the basilar, and indications of this anomaly in other vessels will
be referred to subsequently, but no previous record of its occurrence in the
vertebral is to be found.

Reference to the literature makes it clear that anomalies in this part
of the course of the vertebral are of considerable rarity. Robinson (112)
mentions the possible absence of the upper end of the vertebral, and
Berry and Anderson (24) and Batujeff (13) have each described a case
of failure of union of the two vessels, with consequent abnormal origin
of the basilar.

Branches of the Vertebral Artery.
I. Bulbar.

No attempt has previously been made to investigate this group of
branches.
They may be conveniently divided into three sets :—

A. An upper set, arising from the dorsal aspect of the vessel just
caudal to its termination. They are most numerous in cases
where the anterior spinal arises at an unusually low level, and
then compensate for the deficient distribution of the latter vessel.
Occasionally they are absent. When present they enter the sub-
stance of the bulb either in the antero-median or antero-lateral
fissures, or else in the groove marking the junction of medulla
and pons, in which position they are usually accompanied by
bulbar branches from the lower end of the basilar.

B. “ intermediate set, arising from the lateral aspect of the vertebral,
about the mid-olivary region, and entering the medulla through
the postero-lateral fissure.

They are very variable in size and number, and are quite fre-
quently absent; as I have previously (30) pointed out, this
variability is largely dependent upon the course and distribution
to the bulb of the posterior inferior cerebellar artery.

C. A lower set, consisting usually of one moderately large branch, which
arises from the medial aspect of the vertebral, whilst it is in -
relation to the lateral aspect of the medulla, and at once breaks
up into a number of fine twigs, which enter the lower part of
the bulb. This has been very constantly found in cases where a
sufficient length of the vertebral has been removed with the
brain; but it is liable to be missed by an incomplete removal of
this vessel, and this is probably the reason why it seems to have
been invariably omitted in previous descriptions.

138 Dr J. S. B. Stopford

II. The Anterior Spinal Artery.

This artery normally arises by two delicate branches, one from the
medial side and upper part of each vertebral, which unite on the pyramids
below to form one median branch, or else continue as two separate vessels
after anastomosing. Their continuation down the ventral aspect of the
spinal cord is maintained by reinforcements from various arteries at
different levels. The relative position of the reinforcing arteries and
other structures which pass through the intervertebral foramina has
recently been studied by Swanberg (135), who has found that the vessels
are imbedded in the fat which surrounds and protects the nervous elements.

The right branch of origin was found to be absent in 9 per cent., the
left branch in 3 per cent., and the vessel arose by one stem from the angle
formed by the junction of the two vertebrals in 3 per cent., as pictured
by Willis (155).

In the cases where the vessel exhibited the more Sack double origin,
the right was slightly larger in 43 per cent. and the left in 46 per cent.,
the two being approximately of equal calibre in 11 per cent. In two
instances (Nos. 28 and 147) the left branch had a double origin, and
this was seen on the right side in one specimen (No. 65).

The origin in 51 per cent. on the right and 59 per cent. on the left was
from the extreme upper part of the vertebral (7.e. in the region of the
cephalic extremity of the olivary eminence); in 29 per cent. on the right and
28 per cent. on the left the origin was about the level of the mid-olivary
region, and in 20 per cent. on the right and 13 per cent. on the left it was
at the level of the caudal extremity of, or slightly below, the olive. The
low origin of these branches did not appear to depend upon the junction of
the two vertebral arteries occurring at a lower level than usual, because
in the majority the basilar was formed at the lower border of the pons,
or even above that level. The site of the origin of the anterior spinal is
an important factor in influencing the area of the medulla supplied by the
vertebral, and will be dealt with again more fully in the next section.

In 6 per cent. the right and left branches of origin remained separate,
but in the remainder there were one or more transverse communications
- between the two, or else they fused to form one median vessel—the two
alternatives occurred in exactly equal proportion (47 per cent.). The site
of the communication or fusion was about the level of the lower end of
the olive in 63 per cent., and almost at the junction of the bulb and spinal
cord in 31 per cent., the latter level being the one more frequently found
in the standard text-books. In the remaining 6 per cent. the two vessels
continued their course without any anastomosis, as previously stated.

Anomalies.—Some variation in disposition was commonly found near

©. eer

The Arteries of the Pons and Medulla Oblongata 139

origi but this has apparently no influence upon the distribution, and
nce to fig. % will make clear the variations met with in this series.

; i= A A :

From right vertebral From left vertebral From angle between

rape Syetary only in 9 per cent. only in 3 per cent. the two vertebrals
in 3 per cent.
as Il. us: iit. IV.
Origin.
a AN
Normal level in 63 per cent. Set ‘*decussation ” Absence in
in 31 per cent. : 6 per cent.

Level of fusion or communication.

A kh

No. 19. No. 28. No. 30.

AMA

No.%68.
Seven anomalies.

Fic, 2,—Variations of anterior spinal artery.

The brlbar branches of the anterior spinal may be divided into
Siies sets :—
a A A set of branches arising from the right and left stems before fusion
or communication. These break up, forming a fine network, on

140 Dr J. S. B. Stopford

the upper part of the pyramids in which their terminal filaments
end. A few filaments penetrate the upper part of the antero-
median fissure.

B. Branches which spring from the median vessel (or vessels) after
fusion and pass directly into the antero-median fissure. This
group, especially in the case of the cord, has been studied by
Adamkiewicz (8) and Kadyi (82).

C. Branches from the same origin as the last which pass laterally on
the pyramids, like the transverse pontine branches of the basilar,
and after repeated division penetrate the pyramids or the antero-
lateral sulcus. When the branch of origin of one side is absent
its bulbar supply is invariably furnished by the vertebral.

III. The Posterior Inferior Cerebellar Artery.

The descriptions of this vessel vary within the most extreme limits.
The vaguest references are generally made to its course and origin, although
in recent years its precise anatomy has become of the greatest value, on
account of the well-recognised group of symptoms which its occlusion

produces. Robinson (112), Walsham (149), and Piersol (108) describe it

as arising from the upper part of the vertebral; and almost all the text-
books picture or describe it as passing more or less directly backwards
around the bulb. Cruveilhier (38) gives some indication of its course
when he says: “en décrivant des flexuosités remarquables autour du bulbe
rachidien”; and of more recent writers Charpy (34) gives the most complete
account, which is largely based on Duret’s researches; whilst Wallenberg
(148) has studied it more especially from a clinical standpoint. In a
recent paper (30) I have attempted to give its course more accurately, and
to demonstrate the influence of variation of this upon its distribution.

The posterior inferior cerebellar artery is much the largest branch of
the vertebral—in three cases it was larger than the parent vessel on the
right side in this series—and arises from its lateral side about the lower end
of the olive. After curving round the lower border of the olive it ascends
in the neighbourhood of the postero-lateral sulcus, usually posterior to the
fila of the vagus and glossopharyngeal nerves, almost to the lower border
of the pons, where it changes its direction and forms a loop with its
convexity toward the pons. It now proceeds downwards, with a slight
inclination toward the mid-dorsal line, on the restiform body and the
other infero-lateral boundaries of the fourth ventricle, to just below the
calamus scriptorius, where it turns outward on to the vallecula to divide
into its fully described lateral and medial branches for the supply of the
inferior surface of the cerebellum. In this manner the vessel makes a

as ate

me ae 8 ee ee

oo ee

The Arteries of the Pons and Medulla Oblongata 141

loop with its convexity toward the pons on the lateral aspect of the upper
part of the bulb, the ascending and more anterior limb being shorter and
in relation to the postero-lateral sulcus, whilst the posterior and longer
limb is in relation to the lateral wall of the fourth ventricle.

For clinical application it is necessary to realise that there is a free
anastomosis on the surface of the cerebellum between the three cerebellar
arteries.

The artery has been found to vary considerably in size and course even
on the two sides, as many have previously noticed.

Size.—The two vessels were of equal size in 22 per cent., the right and

Fic. 3.— Course of posterior inferior cerebellar artery.

left were each larger in 39 per cent. In one case the left was four times
the size of the right, and in another three times as large, whilst in three
specimens the right was larger than the vertebral, which was unusually
small, especially above the origin of this branch.

The origin described above as normal was found in 68 per cent. on
the right side and 74 per cent. on the left. In 12 per cent. on the right
and 9 per cent. on the left it arose slightly above this point, and in 17 per
cent. on both sides its origin was considerably below the olive, just cephalic
to the point where the vertebral artery pierced the arachnoid. In 3 per
cent. on the right side it sprang from the vertebral at its termination, just
before it joined with the opposing one to form the basilar.

Its cowrse followed precisely that described as normal in 58 per cent.

142 Dr J. 8. B. Stopford

on the right side and 49 per cent. on the left; but in 6 per cent. on the
right and 19 per cent. on the left the convexity of the loop only ascended
as high as the mid-olivary region. As this minor variation will be seen
not to affect the distribution, for practical purposes it may be stated that
the more usual course is found in 64 per cent. on the right and 68 per cent.
on the left. In 5 per cent. on the right and 4 per cent. on the left the vessel
failed to form any loop, and curved almost directly backward to the
calamus region. In the final group the artery curved backward and caudally
to the spinal cord or directly outward on to the cerebellum ; in either case
it usually failed to provide any bulbar branches; this configuration was
found in 31 per cent. on the right and 29 per cent. on the left, and is
curiously the one most in accordance with the standard descriptions.

Absence.—This artery is not infrequently absent, and was found
wanting on the right side in 15 per cent., on the left in 6 per cent., and
on both sides in 3 per cent. Blackburn (25) found the right absent in
5 per cent. and the left in 3 per cent. When absent, the bulbar branches
are almost invariably supplied by the vertebral, but in one of the above
cases the anterior inferior cerebellar artery provided branches for the
postero-lateral sulcus, whilst in another the internal auditory artery
compensated for the deficiency. The cerebellar branches were found to ~
be replaced by the anterior inferior cerebellar in all cases of absence.

Anomalies.—An abnormal origin was noted three times, and in each
case it was on the right side.

In Nos. 89 and 131 the artery arose from the lowest limit of the
basilar, in the latter case in common with the anterior inferior cerebellar.
Longo (90) found both posterior cerebellar arteries, on each side, arising
from the basilar in one case in his series of fifty.

In No. 24 it had a double origin from the right vertebral, the lower
one at the usual level and the upper one at the mid-olivary region; the
two roots embraced a few fila of the hypoglossal as they converged to form
the main arterial trunk.

In No. 137 a small foramen, exactly comparable to the one described
in connexion with the vertebral, was found in the artery of the left side.
Twice on the right, and in a similar number on the left, the vessel had a
somewhat unusual course, as it proceeded to the dorsal surface of the bulb
and then ascended at the side of the fourth ventricle up to the pons before
passing on to the cerebellum, thus forming a loop in the reverse direction.

Branches.

The most important and interesting are those which supply the medulla
oblongata.

The Arteries of the Pons and Medulla Oblongata 143

—
—

_~A’ Bulbar.—Branches are supplied to the bulb by both limbs. The
ascending limb provides between two and seven minute branches
to the region of the postero-lateral sulcus, whilst the descending
limb supplies a variable number of branches to the region of the
medulla, with which it comes into relation. Frequently the latter
group of branches is entirely absent.

_B. Cerebellar.—The medial and lateral terminal branches have been
seen to anastomose freely with the other cerebellar arteries, but
they have not been studied in any detail.

C. The Choroidal branch to the plexus of the fourth ventricle has not

been fully studied, but in a large number of specimens used for
injection it was found to arise from the upper limit of the loop
in the region of the cerebello-pontine angle. |

D. The posterior spinal in this series has been found to be more
frequently a branch of this vessel than of the vertebral, as dis-
cussed in the succeeding paragraph.

IV. The Posterior Spinal Artery.

This artery has been included as one of the branches of the vertebral,

_ because that is the origin most frequently stated, but it is not in accord-

ance with the findings in this investigation. Duret (55) and Dana (41)

describe its origin as from the posterior inferior cerebellar, but others give

the vertebral, although Henle (72) and Vicq d’Azyr state that it sometimes
arises from the other vessel.

Unfortunately this artery was found intact in a much smaller propor-
tion of specimens than was the case with any of the others, and conse-
quently the percentages cannot be so accurate or valuable. Nevertheless,
the figures are sifficiently convincing to be of assistance in the determina-
tion of the question of origin.

On both sides it arose from the posterior inferior cerebellar in 73 per
cent., and on the right side it sprang from the vertebral in 18 per cent.,
and from the same artery on the left in 20 per cent.

In 9 per cent. on the right and 7 per cent. on the left it had a double
origin, being in communication with both the vertebral and the posterior
inferior cerebellar artery.

It was seen to arise most commonly from the posterior inferior cere-
bellar artery just before the latter vessel extended to the cerebellum ;
and almost at once divided into an ascending ramus, which proceeded
upward on the posterior columns to the region of the calamus scriptorius,
and a descending ramus, which passed downward behind the posterior
roots, to be reinforced in a manner similar to the anterior spinal.

VOL. L. (THIRD SER. VOL. XI.)—JAN. 1916. 10

144 Dr J. S. B. Stopford

The vessel was absent on one or both sides in a large percentage of
cases, but it is quite impossible to give any reliable figures. -

The ascending ramus was also very inconstant.

Numerous minute bulbar branches are given by both rami, when
present, to the posterior columns and their nuclei.

The Basilar Artery.

The basilar artery, formed by the junction of the two vertebrals, extends
from the caudal to the cephalic borders of the pons in the cisterna pontis.
It lies on the ventral aspect in the median groove, which is produced by
the prominences formed on each side by the pyramidal fibres and not by
the pressure of the vessel, as may be demonstrated by the presence of this
groove in cases where the basilar is deflected some distance from the median
plane. Itis only separated from the basisphenoid by the arachnoid and dura.

The origin has been considered in the references to the level of the
junction of the vertebral arteries. In four instances the basilar appeared
to be formed almost entirely by the right vertebral, and in a similar
number by the left; this was the result of the great discrepancy in size
between the two vertebrals in these cases. =

Size.—At its origin the vessel is almost invariably larger than either
vertebral, but there is a gradual and apparent diminution in size as it
is traced to its termination. In three specimens there was an unusually
marked and rapid reduction in calibre.

Termination.—Normally the artery ends at the upper border of the
pons by dividing into the two posterior cerebrals. In two cases this
division was just below the upper border, and in two others it was fully
half an inch below.

The basilar has been found to follow a more constant course than any other
vessel studied in this series,and at the same time it has been seen to exhibit
manifestation of arterial disease much more frequently than the others.

Anomaly.—No. 141 showed a small foramen immediately above the
origin, exactly similar to that once described in the case of the vertebral
and posterior inferior cerebellar arteries.

Foramina have also been noted in this vessel by Blackburn (25),
Longo (90), and Rendall (111).

The only other abnormalities of the basilar which have ever been
reported are :—

(1) The presence of a median septum in the interior denoting incom- |

plete fusion during development, which has been noted by
Blackburn and many others.

The Arteries of the Pons and Medulla Oblongata 145

~

(2) The presence of a band which traverses the lumen in a transverse
direction ; this was seen seventeen times in ninety-eight autopsies
by Davy (43).

a (3) The presence of a communicating branch, generally of considerable

ie size, between the internal carotid and the basilar, as reported by

Elliot Smith (124), Decker (45), Incoranto (79), Duret (54), and

Blackburn (25).

No attempt has been made to search for the former two anomalies, as
it would have damaged the vessels too severely to permit the injections to
be performed later.

From De Vriese’s (49) work on the ontogeny of the basilar, and
Beddard’s (16, 17, and 18) studies of the arteries at the base of the
brain in other vertebrates, it is easy to explain all the anomalies of this
vessel, as they appear without exception to indicate its formation from
the two most caudal branches of the internal carotid.

Branches.
| I. Pontine.
. These may be divided, according to course and disposition, into two
sets :—

A. A median set, composed of minute branches arising from that
surface of the basilar lying in contact with the pons, which at
once enter the substance of the brain along the median groove.
Duret (55) subdivided this set into three groups, but no advantage
ean be gained by this; nor did my own observations justify it.
Certainly they are more numerous caudally, where many enter
the sulcus between the pons and bulb together with branches
from the vertebrals, and again at the cephalic extremity of the
basilar; but between these points they are generally found con-
tinuously, with no suggestion of any definite grouping.

B. A set of transverse rami which extend laterally and subdivide as
they proceed into smaller branches which penetrate the ventral

s surface of the pons at right angles to the parent vessel. These
vessels were generally arranged symmetrically on the two sides,
but were variable in size and number. Normally an unusually
large branch was seen to extend to the trigeminal nerve, which
it supplied in a similar manner to the “radicular” arteries of
Duret. If the meninges and vessels were removed, small orifices
for the entrance of these vessels could be seen on the surface
between the superficial transverse pontine fibres.

146 Dr J. S. B. Stopford

From embryological research and comparative study there is
good reason to conclude that these transverse rami are arranged
segmentally.

Il. The Anterior Inferior Cerebellar Artery.

This vessel normally passes laterally, and somewhat caudally, from its
origin over the ventral surface of the pons towards the cerebellar hemi-
sphere of its own side, on to the anterior part of the inferior surface of
which it extends to anastomose with the posterior inferior cerebellar. In
the region of the cerebello-pontine angle it almost invariably passes
between the pons and the facial and auditory nerves, close to their
superficial origin. In two cases (Nos. 27 and 65), the vessel formed a
complete arterial loop around these two nerves before it approached the
inferior surface of the cerebellum. In one case the vessel was double on
both sides. Blackburn discovered this eight times in 220 examinations.

The size and course of this vessel and the level of its origin from the
basilar are variable even on the two sides; the variation in the former
two depends largely upon the size and distribution .of the posterior
inferior cerebellar.

The left was absent on two occasions, but both in only one case (No. 131).

Size.—The arteries on the two sides were equal in calibre in 15 per
cent., the right was larger in 48 per cent., and the left in 37 per cent.
In six the right was very considerably larger than the left.

Origin.—In 85 per cent. the two were seen to arise at the same level;
of these 78 per cent. arose from the lower third, 17 per cent. from the
middle, and 5 per cent. from the lower limit of the basilar.

Including the 15 per cent. where the vessels of the two sides gained
origin at different levels, it may be said that :—

Right. Left.

Origin was from lower third of basilar in . 75 per cent. 73 per cent.
‘ s middle x eh. See y-} eens
- E lower limit a Seis: Okage 6 Et

On the right side the artery was found to arise from the vertebral
twice and on the left side once.

In one case, on the right, the vessel had a common origin with the
posterior inferior cerebellar from the lower end of the basilar; this has
been previously noted by other observers several times.

Relation to the Abduwcent Nerve-—At the present time this neuro-
vascular relation is clinically of very considerable interest; yet our
anatomical knowledge of the subject is unfortunately incomplete and far
from satisfactory.

The Arteries of the Pons and Medulla Oblongata 147

__The only previous investigation of this relation was made by Cushing
(40), and his conclusions were based on only fifty-nine observations. As
he failed to differentiate between the relations of the anterior inferior
cerebellar and the internal auditory arteries, no object can be served by
comparing his results.

Only two treatises—those of Charpy (34) and Cruveilhier (88)—on
anatomy refer in the text to this relationship. Both describe the artery
as lying sometimes ventrally and sometimes dorsally to the nerve, but
omit any reference to the frequency of the occurrence of either. Bardeleben
(9), Howden (74), Macalister (93), Rauber (110), Robinson (112), Sappey
(118), Spalteholz (126), Thane (139), Toldt (142), Vieq d’Azyr (147), and
Antonius and Caldani (7) all picture the artery as ventral to the nerve;
whereas Turner (144), Walsham (149), Deaver (44), and Charpy (34)
illustrate the reverse, although only the latter makes any reference in
the text.

The present investigation has shown the artery ventral on both sides
in 74 per cent., and dorsal in 8 per cent., and there is a difference in this
neuro-vascular relationship on the two sides in 18 per cent.

Taking all into account, the right was ventral in 86 per cent. and dorsal
in 14 per cent., whilst the left was ventral in 81 per cent. and dorsal in
19 per cent.

It is necessary at this point to realise that when the artery lies in the
dorsal position, the abducent nerve may be compressed against the basi-
sphenoid by the vessel, as the former structure proceeds toward the
cavernous sinus.

In five cases on the right and three on the left the artery was too far
forward to bear any relation to the nerve.

Anomalies.—Absence and the irregular origin from the vertebral have
been referred to previously. The only other anomaly met with was per-
foration of the abducent by the artery, a condition which occurred twice
(Nos. 116 and 137) in this series, and in each case was on the left side.
Nearly three years ago this condition was noted on both sides in a
specimen in our own dissecting room by Mr T. P. Kilner, formerly a
Demonstrator of Anatomy in this Department, but this has not been
included in the 150 brains described. Valenti (145) first observed this
abnormal relation, and more recently Cushing (40) discovered it three
times in fifty-nine brains, and in each case it was on the left side.

Consequently in the six examples cited above, it was present five times
on the left only and once it was bilateral.

No effort appears previously to have been made to elucidate or explain
‘the etiology of this anomaly; but, in the light of the researches of

L148 Dr J. 8. B. Stopford

Belogolowy (21) in the chick, and Bremer (28) and Elze (58) in the
human embryo, it is not difficult to appreciate the cause of its presence.

A. Artery ventral,

B. Artery dorsal.

Fic. 4.—Relative position of VIth nerve and anterior inferior cerebellar artery.

The above researches have shown that the abducent originally arises by
many roots which are arranged segmentally. Normally in man the inter-
mediate ones alone remain, but persistence of the others may occur and

The Arteries of the Pons and Medulla Oblongata 149

constitute aberrant roots, which have been fully described by Bremer.
Between these segmentally arranged roots transverse branches of the
basilar have been seen*by Elze and Bremer; from this it would appear
likely that, in cases of perforation of the VIth nerve, the anterior inferior
cerebellar passes between the true root and an aberrant one.

A very complete bibliography of the morphology of the abducent and
other nerves supplying the eye muscles has been given by Neal (101).

This emphasises Cunningham’s (39) statement—‘“ Nerves are the most
conservative of all structures which go to build up the human body. They

Fie. 4.—C. ‘‘ Splitting” of nerve on left by artery.

cling most tenaciously to old traditions, and travel most pertinaciously
along the old beaten paths.” i

It is interesting to notice that the plates of many of the older writers
(Vieq d’Azyr, Caldani, etc.) represent the abducent as formed by two
distinct roots, of which the more medial is smaller.

Branches.

A. Pontine.—A few branches were given to the more caudal and lateral
part of the pons, in a similar manner to the perforating rami of
the transverse pontine branches of the basilar.

B. Bulbar.—In a few cases small branches were given to the upper part
of the postero-lateral sulcus, when this region was incompletely
supplied by the posterior inferior cerebellar. Quite frequently
branches enter the sulcus between the pons and the bulb.

150 Dr J. S. B. Stopford

C. Internal Auditory.—Full reference will be made to the origin of
this artery in the next paragraph.
Cerebellar.—Chiefly destined for the supply of the inferior surface
of the cerebellum together with the posterior inferior cerebellar
artery.

Ill. The Internal Auditory Artery.

The presence of this artery was somewhat inconstant, but no accurate
percentage could be given owing to the frequency with which it is
damaged in the removal of the brain. As a branch of the basilar, it is
undoubtedly more frequently absent than present.

It is customary to describe it as arising from the basilar and as passing
laterally and slightly caudally to reach the auditory nerve, which it
accompanies into the internal auditory meatus.

Origin.—The conclusion drawn from this examination is that it arises
more frequently from the anterior inferior cerebellar than the basilar, as in
64 per cent. on the right and 62 per cent. on the left it was given off by
the former artery. It is usually seen to arise at the point where the
anterior inferior cerebellar leaves the brachium pontis and extends on to
the cerebellum, a point where the artery is in close relationship with the ~
auditory and facial nerves.

In 13 per cent. on the right and 10 per cent. on the left it was seen to
spring from the basilar immediately above its origin, in 20 per cent. on the
right and 18 per cent. on the left it came off from the junction of -lower
and middle thirds, and in 3 per cent. on the right and 10 per cent. on the
left it was derived from about the middle.

Size.—It is generally quite small, but in one case it was unusually large.
The vessels of the two sides were equal in size in 15 per cent., in 50 per
cent. the right was larger, and in 35 per cent. the left.

Relation with Abducent Nerve.—Clinically this relation cannot be so
important as that in the case of the anterior inferior cerebellar. In the
first place, on account of its diminutive size, the risk of compression or
strangulation of the VIth nerve must be materially reduced even in those
cases where it does arise from the basilar (36 per cent. on the right and
38 per cent. on the left); and secondly, its frequent origin from, the
anterior inferior cerebellar prevents the possibility of any intimate relation
between the two structures occurring in 64 per cent. on the right and
62 per cent. on the left. In those cases where this neuro-vascular relation
could be considered, it was found that the artery passed dorsal to the nerve
in 10 per cent. on the right and 16 per cent. on the left. In one of these,
on the left, the artery arose from the anterior inferior cerebellar on the

The Arteries of the Pons and Medulla Oblongata 151

_medial side of the nerve; but in every other case the origin from this artery

was lateral to the nerve and generally at the point previously described,
so that the two were mever intimately related to each other. It is of
interest to notice that both the internal auditory and the anterior
inferior cerebellar arteries take the dorsal course more frequently on
the left. Both these arteries were seen to pass dorsally in the same
specimen on the right side in 6 per cent., never on the left alone, and
only in one instance on both sides. Cushing (40) states that sometimes
both arteries may be dorsal on one side, but it is unusual to find it on
both sides, and these figures support that supposition.

Branches.

A. The main vessel supplies the auditory nerve and the internal ear.
B. Occasionally a few bulbar, pontine, or cerebellar branches are to
be seen.

IV. The Superior Cerebellar Artery.

The presence, origin, and course of this artery were all found to be
very constant.

_ It arises from the basilar, close to the point where it bifurcates to
form the posterior cerebral arteries, and, after extending laterally immedi-
ately caudal to the oculomotor nerve, curves round the crus cerebri to
gain the superior surface of the cerebellar hemisphere of its own side.
On the surface of the cerebellum it divides into numerous branches, which
freely anastomose with the other cerebellar arteries. The injection experi-
ments have proved that there is quite a free communication between the
cerebellar arteries of the two sides, and this anastomosis must be an
important factor in preventing softening of the cerebellum in many cases
of occlusion of one or more of these arteries.

In the case of the cerebral arteries a similar anastomosis was found by
Beevor (19) to exist in the pia mater.

Size.—The arteries of the two sides were of equal size in 33 per cent.,
in 31 per cent. the right was larger and in 36 per cent. the left.

Diminutive size, or absence, of one or other cerebellar artery is invari-
ably provided for by an increase in calibre of one of the others, so that
there appears to be a compensatory provision for the supply of a more or
less definite volume of blood to the cerebellum.

The origin, as stated, was found to be very constant. In 94 per cent.
it was at the upper limit of the basilar, practically at the upper border
of the pons, just caudal to the point where it divided into the posterior
cerebral arteries. In 6 per cent. the origin was slightly caudal to this

152 Dr J. S. B. Stopford

point, so that the relationship to the oculomotor nerve was more remote.
In one case the right superior cerebellar sprang from the basilar at the
junction of its upper and middle thirds.

The vessel was only absent once, and then only on the left side, when
is was replaced by branches from the posterior cerebral. Longo (90)
quotes a similar example, but Blackburn (25) found the vessel constantly
represented in the 220 he examined.

Duplication.—The vessel was found to be double in a large number
of cases; in 12 per cent. the right only, 16 per cent. the left only, and 3 per
cent. on both sides. Once on the left it was represented by three vessels.
Blackburn found it duplicated on the right only in 2 per cent., left only
in 1 per cent., and on both sides in 1 per cent. In about 4 per cent., on
each side, the artery was found to divide into two immediately distal to
its origin.

The explanation of duplication of the cerebellar vessels necessitates
only a passing reference to Mall’s (94) research on the development of the
intracranial blood-vessels, by which he proved that the cerebellar arteries
are represented primarily by a cluster of branches, but later become
reduced to a single vessel: Persistence of more than one of these branches
will result in duplication, and similarly the explanation of double origin,~
as described in the case of one posterior inferior cerebellar artery, becomes
clear. In a previous paper (134) I discussed the anomalies of the renal
and spermatic vessels, and many of the opinions expressed there may be
applied to the present question.

Branches.
A. Pontine —The artery was found to give frequently a few irregular
branches to the pons as it extended laterally from its origin.
B. Mesencephalic.—These have not been studied, as they were very
fully described by Alezais and d’Astros (5).
C. Cerebellar.—Destined chiefly for the supply of the superior surface
of the cerebellum.

V. The Posterior Cerebellar Artery.

This branch of the basilar will be briefly referred to in the section on
the arteries forming the circle of Willis. The two vessels at their origin
form approximately an angle of 90°.

B.—THE CiRcULUS ARTERIOSUS (WILLISII).

This significant anastomosis, between the intracranial branches of the
internal carotid and basilar arteries, is situated in the cisterna inter-

ee gers.

The Arteries of the Pons and Medulla Oblongata 153

-peduncularis. It has been very systematically and extensively studied
by many observers, which was to be expected in view of its great
anatomical, physiologicaf medical, surgical, and even pathological interest.
The more recent and extensive investigations have been performed by
Blackburn (25), Windle (157), Fawcett and Blackford (59), De Vriese (50),
and Longo (90), in man, and by Beddard (16, 17, and 18) in other mammals.

My own observations on this arterial circle will be briefly stated and
then tabulated, together with those most recently made (see Table I1.).

All the vessels comprising the circle of Willis were intact in 105
specimens, and there was a complete circular anastomosis in 98 (93 per
cent.) of these, the deficiency in six of the remainder being due to the
absence of the posterior communicating on one or the other side. One
would expect this to be the vessel most frequently absent, because its
importance is relatively much greater during the early weeks of intra-
uterine life, when it represents the origin of the posterior cerebral from
the internal carotid, than later, when the posterior cerebral is reinforced
by anastomosis with the basilar and the posterior communicating is no
longer essential for the maintenance of the blood supply of the posterior
part of the cerebrum. Consequently, the posterior cerebral normally trans-
fers its origin from the internal carotid to the basilar, with the result that
the posterior communicating attains its maximum functional importance

_ very early, but soon loses it, owing to the development of the anasto-

mosis between the posterior cerebral and the basilar; and from that time
onward fails to increase in size at the same rate as the other arteries. In
cases where the anastomosis between the posterior cerebral and basilar is

feeble and insufficient, the posterior communicating does not lose its

function but persists as the main channel of supply to the main trunk
of the posterior cerebral. Under these circumstances the posterior com-
municating is frequently larger than the origin of the posterior cerebral
from the basilar, and the latter in consequence appears to be a branch. of
the internal carotid. That is to say, what appears in the adult to be a com-
pensatory enlargement of the posterior communicating, to accommodate
for its abnormally small origin from the basilar, is, strictly speaking, a
persistence of the embryonic condition. Clinically, one would expect, even
momentary, obstruction of the internal carotid in these cases to manifest
more widespread and alarming symptoms than cases where the circle of
Willis conformed to the more normal arrangement. The seventh instance
of an incomplete circle illustrates perfectly the embryonic condition, because
it represents complete failure of development of the anastomosis between
the basilar and the posterior cerebral, and consequently in this case the
latter vessel is a true branch of the internal carotid.

154 Dr J. 8. B. Stopford

The Posterior Cerebral Artery.

As is to be expected from the above account, the size of the origin of
this vessel from the basilar was inversely proportionate to the size of the
posterior communicating in all (except one case). /

The size of the origin of the arteries of the two sides was equal in
32 per cent., the right was larger in 36 per cent., and the left in 32 per cent.
No observer has previously determined the relative sizes of the two at their
origin, although clinically this must be the most important point. The artery
appeared to arise chiefly from the internal carotid, on both sides in 2 per
cent., the right only in 5 per cent., and the left side only in 3 per cent.

In No. “41 the posterior cerebral sprang from the internal carotid
alone, owing to the failure of its normal post-fcetal origin from the basilar.

In No. 73 the vessel was double, the supernumerary ramus being a
branch of the posterior communicating. Shaw (125) described two
examples of duplication of this artery, one on the right side and one on
the left; both consisted of a double origin from the basilar, and in both
the two branches united immediately after junction with the posterior
communicating. Reduplication of this artery is apparently extremely
rare, as there are no other records of such an occurrence. -

In No. 120, as previously indicated, the left posterior cerebral provided
the superior cerebellar of that side. Normally the artery passes anterior
to the oculomotor nerve, but it is only in actual contact in about 50 per
cent. Windle (157) reports a case in which the oculomotor was divided
by a branch of the posterior cerebral. In four instances the basilar was
found to bifurcate below the normal position (upper border of pons), in
which case the posterior cerebral must inevitably make a more pronounced
loop round the IIIrd nerve and consequently endanger the nerve by
strangulation, if any force acting in a caudal direction is exerted upon it.

Lautard (86) described very fully the abnormal vessels which compensate
for a very small posterior cerebral artery.

The Posterior Communicating Artery.

This branch of the internal carotid was present in 93 per cent. on both
sides, and was absent in 4 per cent. on the right and 3 per cent. on the
left. The arteries of the two sides were of equal size in 28 per cent., the
right was larger in 35 per cent., and the left in 37 per cent. This is in
direct contradiction to the opinion of Box and Eccles (26), who maintain
that the right posterior communicating is invariably the larger. Both
were unusually large in 3 per cent., and the vessel of either side alone was
of extreme size in 1 per cent. Both were minute in 3 per cent., and the
left alone was particularly small in 2 per cent.

The Arteries of the Pons and Medulla Oblongata 155

On both sides in 2 per cent. the posterior communicating was larger

than the origin of the posterior cerebral from the basilar, and as a result
the latter vessel appeared to be a branch of the internal carotid; this
occurred on the right alone in 3 per cent., and the left alone in 3 per cent.

The Anterior Cerebral Artery.

No marked abnormality of this vessel was noticed. The relative size
is of little clinical importance, owing to the practically constant presence
of the anterior communicating.

Barkow (10) described a case in which the anterior cerebral arteries
fused to form one common trunk in a similar manner to the junction of
the vertebrals to form the basilar, a condition found constantly in the
lower mamunals.

Beaumonoir (15) quotes a case in which the right middle cerebral gave
origin to the anterior cerebral artery of both sides. In No. 123 an accessory
middle cerebral was found, arising from the left anterior cerebral at the
level of the junction with the anterior communicating.

The presence of a middle anterior cerebral, in addition to the right and
left, has been noted frequently since the time of Barbieri (8). It was
discovered in 6 per cent.

The Middle Cerebral Artery.

No abnormality in origin or size of this branch of the internal carotid
has been noted.

The Anterior Communicating.

A communication between the two anterior cerebral arteries was found
constantly. Barbieri (8), Spitzka (131), and Blackburn (twice in 220) have
seen examples of its absence, but it is a very rare condition. A normal
single channel was found in 85 per cent., a double communication (partial
or complete) in 9 per cent., and in 3 per cent. there was lateral fusion for
a short distance without the intervention of any communicating branch.
In No. 118 the anterior communicating exhibited a “dimpling,” which
indicated an attempt at duplication. In one case there was a triple com-
munication, and in another a quadruple or what might be more correctly
termed an anastomatic network.

Reference to fig. 5 will make the arrangement of this vessel clearer.
Ehrman (56) found the anterior communicating single in 89 per cent.,
double in 3 per cent., triple in 2 per cent., Y-shaped in 3 per cent., and
fusion of the two anterior cerebral arteries in 3 per cent. Mori (99) noted
reduplication of the anterior communicating in 14 per cent.

156 Dr J. S. B. Stopford

Parsons (107) found this artery absent in many mammals, including
Platyrrhine monkeys, the two anterior cerebrals forming a single azygos —
vessel, which supplies the medial surfaces of both cerebral hemispheres.

Griinbaum and Sherrington (65) found the human type more constant
in the chimpanzee and orang, but not invariably present. De Vriese

| | Ant. cerebral.
sree Y Mid. cerebral. : ay

Post. communicating.

Normal in 85 per cent. Fusion.

Absence of true ant.
commun. in 3 per cent.

Ls |
AGE&

2 Il. Iii. aYV<
Four forms of reduplication of ant. communicating (9 per cent.).

Ant. communicating ‘‘ triple.” Quadruple (network).

Fic. 5. —Variations of anterior communicating artery.

(47) and Beddard (16, 17, and 18), as in the case of the other cerebral
arteries, describe in great detail the morphology and comparative anatomy
of this vessel.

The Internal Carotid.

The only thing in connexion with this artery which has been specially
noticed is its close approximation to the optic nerve. This will be con-
sidered fully in Part III.

Mitchell and Dercum (98) describe a most interesting case of aneurysm

The Arteries of the Pons and Medulla Oblongata 157

an abnormal communication between the terminal parts of the two
I carotid arteries. A similar abnormal communication is 8 mentioned
ne O1 nto.

TaBLe II
d| 3g | 2.| 2s
x es < Pats >| 3s
‘E BS
é % E 33 o3 ae
D B e 2a a& | a~
Percentages,
mined =... | 160 | 80 | 900 | Oo). | 88
circle of Willis. . : .| 93 a 59 96 7“ 96
oa
(b) Right larger . eee a tO a a “se was
(ce) Leftlarger . y : . 32 sas ied ae sie
vj 2 Appeared to ne chiefly from Sides
(a) Bothsides .. 2 10 2 30 ‘
— (b) eal 5 7 5 1 aes 20
=n ©] side only 3 5 4 1 8
II. Posterior Communicating.
it. z . ae “ . |. 98 ere 87
No Bat ee es 0 toh 1 4 4
Right on * a ; ; 4 4 | one casc 4 2 iss
3 Ea * uke Sire Meee 3 eta 6 1
. Pe a - |.°28 eas oe 89 38 40
% i langer : : . .| 35 ee os 12 30 32
Remene ee ae a aa 9 32 28
le | ee heeds Po
(db) Right only peat a pOtang tee 1 ee - “ae a 12
"7 eae 2S Ag a 1 =} a ee i an
. Minute:
F. ; 7 : é . 3 2 3
co O tonly . ? é : 3 0 1 ees 3
oe o Rig oy : , : y 2 3
IL. Anterior Communicating
Absence. 0 1 1 | one case oe
> Bs ef a 85 90 79 92 48 80
_ 2. Double. ; ° 9 6 10 7 14 4
3. Triple . é 1 ... | One case/one case! ... see
|. Quadruple or retiform reer 1 |onecase|... oe 28 12
| 5, Fusion of anterior cerebrals : 3 3 3 ae 10 4
hy Presence of “op. pega ease anterior . 6 1 4 3 12 8

158 Dr J. S. B. Stopford

The Frequency of Anomalies in Criminals and the I nsane.

In the preface reference has been made to the conclusion that anomalies
in the basal arterial trunks occur more frequently in the insane. This
conclusion is supported by the results in this series, which is composed of
117 brains from sane individuals and 33 from insane; anomalies were
found in 61 per cent. of the former and 79 per cent. of the latter. Con-
siderable emphasis has been placed upon this point by many previous
writers, and for comparison the various results will be found tabulated
in Table III. Unfortunately, this table loses a good deal of its value,
because the various recorders have failed clearly to define what they con-
sider as anomalies, and the greatest reliance can therefore be placed upon
the results where the percentages are obtained by the same observer both
for the insane and healthy. In this series, absence, irregular origin,
reduplication, or a considerable discrepancy in size of any artery has
constituted an anomaly.

Tas_e III.
Number _ Percentage of
Observer. Examined, ete. Anomalies.
Blackburn (25), 220 insane. 70
Barbieri (8). 145 idiots. 15
Frigerio (61). 37 insane, 57
Lombroso (89). 71 criminals. 37
Mori (99). 35 insane. 91
35 sane. 37
Parnisetti (106). 65 criminals. 51
Windle (157). 200 sane. 40
STOPFORD. 118 sane. 61
32 insane, 79
BIBLIOGRAPHY.

(1) Apranamson, I., “A Case of Thrombosis of the Posterior Inferior
Cerebellar Artery,” Journ. Nerv. and Ment. Dis., vol. xxxv., 1908 (New York Neur.
Soc.).

May Avamxkigwicz, A., “Die Arterien des verlaengerten Markes,” Denkschr.
Akad. Wiss. Wien, Bd. lvii.

(3) Apamxrewicz, A., ‘Ueber die mikroskopischen Gefiisse des menschlichen -
Riickenmarkes,” 7'rans. Inter. Med. Cong. Lond., 1891, vol. i.

(4) ALexanpeER, W., ‘“‘ Observations on the Effect of Ligature of the Vertebral
Artery in certain Diseases of the Spinal Cord,” Liverpool Med.-Chir. Journ., ii., 1882.

The Arteries of the Pons and Medulla Oblongata 159

ie -Anezais et v’Astros, “La circulation artérielle du pédoncle cérébral,”
Journ. de Vanat. et de la phys., xxviii., 1892.

(6) Anperson, R. J., “A New Abnormality in connection with the Vertebral
Artery,” Jowrn. Anat. and Phys., xiv., 1879-80.

(7) Antonius, L. M., and Caupanl, F., Jcones anatomice, vol. iii. part iv., 1813.

(8) Barsrert, A., Monographia della arteria vertebrale, Milan, 1867-8.

(9) BarpELEBEN, K. von, “ Nervensystem,” in Handbuch der Anatomie der
Menschen, Jena, 1899.

(10) Barkow, H. O. L., Schlagad. der Sdugethiere, 1866, Taf. 43, quoted by
Mitchell and Dercum (98).

(11) Bastian, C., “ Thrombosis of Basilar Artery,” Lancet, i. 1885 (Proc, Chir.
Soc. London).

(12) Barren, F. E., “Bulbar Palsies,” in Allbutt and Rolleston’s System of
Medicine, vol. vii.

(13) Baruserr, N., “Eine seltene Arterienanomalie: Ursprung der Basilaris
und der Carotis interna,” Anat. Anz., iv., 1889.

(14) Beapies, C. F., “Aneurysms of the larger Cerebral Arteries,” Brain,
vol. xxx., 1907.

(15) Beaumonorr, Les progrés médical, 1886.

(16) Bepparp, F. E., “A Contribution to the Knowledge of the Encephalic
Arterial System in Sauropsida,” Proc. Zool. Soc. Lond., vol. ii., 1905.

(17) Bepparp, F. E., “A Contribution to the Knowledge of the Arteries of the
Brain in the Class Aves,” Proc. Zool. Soc. Lond., vol. i., 1905.

(18) Bepparp, F. E., “On the Arteries at the Base of the Brain in some
Mammals,” Proc. Zool. Soc. Lond., vol. i., 1904.

(19) Brevor, C. E., “On the Distribution of the different Arteries supplying
the Human Brain,” Phil. Trans. Roy. Soc., ser. B, vol. cc., 1908.

(20) Besvor, C. E., “The Cerebral Arterial Supply,” Brazn, vol. xxx., 1907.

(21) Betocgotowy, J., “Zur Entwickelung der Kopfnerven der Vogel: ein
Beitrag zur Morphologie des Nervensystems der Wirbeltiere,” Bull. Soc. Imp.
Moscow, Abt. iii., unce iv. -

(22) Berkey, Mental Diseases, 1900.

(23) Bernuermer, “Ueber die Sehnervenverinderungen bei Hochgradiges der
Gehirnarterien,” Arch. fiir Ophthal., Bd. xxxvii. 8. 3.

(24) Berry, R. J. A., and Anberson, J. H., ‘A Case of Non-Union of the
Vertebrals, with consequent Abnormal Origin of the Basilar,” Anat. Anz., xxxv., 1910.
» (25) Buacksurn, J. N., “Anomalies of Encephalic Arteries among the Insane,”
Journ, Comp. Neur. and Psych., xvii., 1907.

(26) Box, C. R., and Eccies, W. M‘A., Clinical Applied Anatomy, 1906.

(27) Bramwe.1, Byrom, Edin. Med. Journ., vol. xxxii., 1886-7.

(28) Bremer, J. L., “Aberrant Roots and Branches of the Abducent and
Hypoglossal Nerves,” Journ. of Comp. Neur. and Psych., xviii., 1908.

(29) Bruce, A., J/lustrations of the Nerve Tracts in the Mid and Hind Brain,
1892.

(30) Bury, J. S., and Sroprorp, J. S. B., “On a Case of Occlusion of the
Posterior Inferior Cerebellar Artery,” Med. Chron., Dec. 1913.

(31) Buzzarp, T., “On Posterior Sclerosis, consecutive to Disease of Blood-
vessels,” Brain, vi., 1883.

(32) Camesett, A. W., “Case of Thrombosis of the Left Inferior Cerebellar
Artery, with Cord Lesion,” Liverpool Med.-Chir. Journ., vol. xiv., 1894.

' VOL, L. (THIRD SER. VOL. XI.)—JAN. 1916, ll

160 Dr J. S. B. Stopford

(33) Caapwick, C. M., ““Embolus of the Basilar Artery,” Brit. Med. Journ.,
i., 1886,

(34) Carry, A., “Systeme nerveux,” Poirier and Charpy’s 7'raité d’anatomie,
Qme.éd., tome iii.

(35) Couptanp, “Thrombosis of Anterior Spinal Artery,” Middlesex Hospital
Report, 1889.

(36) Courtney, J. W., “Case of Thrombosis of the Left Posterior Inferior
Cerebellar Artery,” Boston Med. and Surg. Journ., vol. clxvi. 1, 1912.

(37) Corry, quoted in Poirier and Charpy’s 7'’raité d’anatomie.

(38) CruverLurEr, J., Z’raité d’anatomie descriptive, 3™° éd., tome ii., 1851.

(39) CUNNINGHAM, D. J., “The Significance of Anatomical Variations,” Journ.
Anat. and Phys., xxxiii., 1899.

(40) Cusine, Harvey, ““Strangulation of the Nervi abducentes by Lateral
Branches of the Basilar Arteries in Cases of Brain Tumours,” Brain, vol. xxxiii.,
1910-11.

(41) Dana, C. L., “Acute Bulbar Paralysis due to Hemorrhage and Softening
of the Pons and Medulla,” Med. Rec., vol. lxiv., 1903.

(42) Dauper, ‘Zur Lehre von der Poliomyelitis anterior acuta,” Deutsche
Zeitschrift fiir Nervenheilkunde, Bad. iv.

(43) Davy, J., “On a Peculiarity of Structure occasionally occurring in the
Basilar Artery of Man,” Researches Phys. and Anat., vol. i. chap. xvi.

(44) Deaver, J. B., Surg. Anat., vol. ii., 1901.

(45) Decker, quoted by Mitchell and Dercum (98)..

(46) DELPECK, Bull. Soe. Anat. de Paris, vol. xvii., 1843.

(47) De Vriesz, Berra, ‘ Zur Entwicklungsgeschichte der Arterize covelieial
anteriores,” Verh. anat. Ges., 21. Versamml, Wiirzburg, 1907.

(48) De Vrissz, Berra, “Sur la signification morphologique des artéeres
cérébrales,” Arch. Biol. Xxi.

(49) De Vrtzszg, BERTHA, “Recherches sur la morphologie de l’artére basilaire,”
Diss. Inaug. Univ. Gand, 1905.

(50) De Vrresz, Burra, “Sur les artéres de la base cerveau,” Anat. Anz.,
xVii.—xx., 1903-6.

(51) ‘DRESCHFELD, J., ‘Acute Disseminated Myelitis,” Brit. Med. Journ., i., 1894.

(52) Durrin, “ Thrombosis of Vertebral and Basilar rebar aga ta Med. Times and
Gazette, ii., 1876.

(53) DuminiL, “ Atrophie des nerfs hypoglosses, faciaux, spinaux et racines
antérieures des nerfs rachidiens,” Gaz. Heldowr, 1869.

(54) Durer, H., “ Recherches anatomiques sur la circulation de Vencéphale,”
Arch, de Physiol., 1874,

(55) Durer, H., “Sur la distribution des artéres nouriciéres du bulbe rachidien,”
Arch. de Physiol., 1873.

(56) Enrman, Thése de Strasbourg, 1858.

(57) Ercunorst, “ Erweichungsheit in der Varolsbriiche in Folge von syphili-
tische Entartung der Arteria basilaris,” Char. Annal., Bd. i., 1876.

(58) Eze, C., “Beschreibung eines menschlichen Embryo von zirca 7 mm.,”
Anat. Hefte, 1907.

(59) Fawcert, E., and Buackrorp, J. V., “The Circle of Willis: an Examination
of 700 Specimens,” Journ. Anat. and Phys., vol. xl., 1906.

(60) Fiemine, R. A., “Notes of a Case of Recurrent Paralysis of the Third
Nerve,” Rev. of Newr. and Psych., vol. xii., 1911.

The Arteries of the Pons and Medulla Oblongata 161

___ (61) FRicerio, quoted by Charpy (34).

(62) Gruuis, A. C., “Occlusion of the Posterior Inferior Cerebellar Artery,”
Report of Cases, Jowrn. of Amer. Med. Assoc., vol. lxiii., 1914.

(63) GotpscuErpEeR, ‘‘ Ueber Poliomyelitis,” Zeit. fiir klin. Med., Bd. xxii.
Hefte 5 und 6.

64) Gowrrs, W. R., Diseases of the Nervous System, vol. ii., 1893.
65) Grinpaum, A. 8. F., and Suerrineron, C. S., “Note on the Arterial
Supply of the Brain in Anthropoid Apes,” Brain, vol. xxv., 1902.

(66) Hate Wuirs, W., “Symmetrical Intracranial Aneurysm of the Vertebral
Arteries, producing Symptoms resembling Cerebro-spinal Meningitis,” Z’rans. Path,
Soe. Lond., vol. xli., 1890. ;

(67) Hamiron, “On Reflex and Primary Paraplegia,” Brit. and For. Med.-
Chir. Rev., vol. lxii., 1876.

(68) Hanprorp, H., “Thrombosis of the Vertebral and Basilar Arteries,”
Brit. Med. Jowrn., i., 1891 (Proc. Nat. Med.-Chir. Soc.).

_ (69) Harris, W., “A Case of Thrombosis of the Left Posterior Inferior

Cerebellar Artery followed by Trigeminal Neuralgia in the Analgesic Facial Area,”

Proc. Roy. Soc. Med., vol. iii. part ii., 1909-10.

(70) Hayem, “Sur la thrombose par artérite de tronc basilaire comme cause de
mort rapide,” Arch. de Phys., tome i., 1868.

(71) Heap, H., and Gorpoy, Hotmgs, “Sensory Disturbance from Cerebral
Lesion,” Brain, vol. xxxiv., 1911-12.

(72) Hentz, J., Handbuch der Gefisslehre des Menschen, 1868.

(73) Heuser, Die luetische Erkrankung der Hirnarterien, Leipzig, 1874.

(74) Hownen, R., Gray’s Anatomy, Descriptive and Applied, 1913.

(75) Hureutyson, Trans. Clin. Soc., vol. viii., 1875.

(76) Hueuiines Jackson, J., “Softening of the Brain,” Lancet, ii., 1875.

(77) Hun, H., “Analgesia, Thermic Anesthesia, and Ataxia, due to Occlusion
of = Left Posterior Inferior Cerebellar Artery,” New York Med. Journ., vol. lxv.,
1897,

(78) Hurst, “Tribut 4 histoire de l’embolie des artére vertébrales,” Thése de
Paris, 1873.

(79) Incoranto, A., “Di un’ anomalia del polygono arterioso cerebrale
coincidente con asimmetria del cranig,” Atti Acad. Med. di Roma, 1878.

(80) Jeanty, “De l’embolisme cérébral de la sylvienne droite,” Thése de Paris,
1894.

(81) Jones, E., “The Question of the Side affected in Hemiplegia and in
Arterial Lesions of the Brain,” Quart. Journ. of Med., vol. iii., 1910.

(82) Kapyt, H., “Ueber* die Blutgefiisse des menschlichen Riickenmarkes,”
Anat. Anz., i., 1886.

83) Kineston, Edin, Med. and Surg. Journ., vol. lvii., 1842.

84) Kurppet and Borrgan, Bull. Soc. Anat. de Paris, vol. Ixvii., 1892.

(85) Kouisko, Ueber die Beziehung der Arteria choroidea anterior zum hintern
Schenkel der inneren Kapsel des Gehirnes, Wien, 1891.

(86) Lavurarp, M , *‘ Etude sur les anomalies des artéres de la base de l’encéphale,”
Thése de Paris, 1893.

87) Lesert, Bull. Soc. Anat. de Paris, vol. xi., 1836.

tes} Leiwy, J., “Multiple Thrombosis of the Circle of Willis,” Med. News,
vol. lxiv., 1894.

(89) Lomsroso, C., quoted by Charpy (34).

162 Dr J. S. B. Stopford

(90) Longo, L., ‘Le anomalie del polygono di Willis dell’ uomo studiate
comparativomente in alcuni mammiferi ed ucelli,” Anat. Anz., xxvii., 1905.

(91) Loomis, Med. Record, i., 1872.

(92) Lozwenre.p, L., ‘Zur Lehre von der Miliaraneurysmen des Gehirns,”
Wien. med. Wochenschr., xxxvii., 1887.

(93) MacatistEr, A,, A Text-book of Human Anatomy, 1889.

(94) Mau, F. P., “On the Development of the Blood-vessels of the Brain in
the Human Embryo,” Amer. Journ of Anat., vol. iv., 1904.

(95) Martz, Legons sur les maladies de la moelle, Paris, 1892.

(96) Maupstey, H., “Embolism of the Basilar Artery, with Meningeal
Hemorrhage from Rupture of Posterior Cerebral,” Zvans. Path. Soc. Lond.,
vol. xxxviil., 1887.

(97) Menzizs, W. F., “Thrombosis of Inferior Cerebellar Artery,” Brain,
vol. xvi., 1893.

(98) Mircneuy, S. W., and Dercum, F. X., “‘ Aneurysm of an Anomalous Artery
causing Antero-posterior Division of Optic Nerves and producing Bitemporal
Hemianopsia,” Jowrn. of Nerv. and Ment. Dis., vol. xiv., 1889.

(99) Morr, A., “Sulla disposizione delle arterie della base dell’ encefalo nei
normali e negli alienati,” Mon. Zool. [tal., iv.

(100) Moxon, W., ‘‘Influence of the Circulation on the Nervous System,”
Lancet, i., 1881.

(101) Near, H. V., ‘The Morphology of the Eye Muscle Nerves,” Jowrn. of
Morph., vol. xxv., 1914.

(102) OBERSTEINER, H., Anleitung beim Studiwm des Baues der Nervosen Central
organe, Leipzig, 1888.

(103) Oaxx, J. W., “ Note on a Nerve piercing the Walls of an Artery,” Journ.
of Anat. and Phys. vol. xxix., 1895.

(104) Oa, Med.-Chir. Trans., vol. xlii., 1859,

(105) ORMEROD, te. “Two Cases to illustrate Disease of the Medulla
oblongata and Pons varola, ‘» St Barts Hosp. Reports, vol. xliii., 1907.

(106) ParnisErti, “Anomalie del poligono arteriose del Willis nei delinquenti
in rapporto con alienazioni del cervello e del cuore,” Arch. Psych. Se. peu ed Antrop.,
xxiii.

(107) Parsons, quoted by Griinbaum and Sherrington (65).

(108) Prersot, G. A., Human Anatomy, 1907.

(109) Porn, F. M., ‘Thrombosis of Vertebral Artery pressing on Glosso-
pharyngeal Nerve: Unilateral Loss of Taste at. Back of Tongue,” Brit. Med.
Journ., ii., 1889.

(110) Raver, Lehrbuch, 7th ed., Leipzig, 1906.

(111) BRenpaui, S. M, “Unusual Abnormality of the Arteries at the Base of
the Brain,” Journ. of Anat. and Phys., vol. xiii., 1879.

(112) Ropinson, A., “The Vascular System,” in Cunningham’s Text-book of
Anatomy, 4th ed.

(113) Rostyson, G. W., “ Occlusion of the Posterior Inferior Cerebellar Artery,”
Journ. of Amer. Med. Assoc., vol. lxi., 1913.

(114) BRompsre, Diseases of Nervous System, London, 1853.

(115) Boss, J, “Distribution of the Arteries of the Spinal Cord,” Brain,
vol. iii., 1880.

(116) Ross, J., A Treatise on the Diseases of the Nervous System, vol. ii., 1883,

(117) Ruyson, F., Zpistola problematica prima, Amsterdam, 1724.

The Arteries of the Pons and Medulla Oblongata 163

~—~(118) Sappsy, C., “ Myologie, Angiologie,” 7razté d’anatomie, tome ii., 1869.
(119) Savetiev, quoted in Osler’s Principles and Practice of Medicine, 7th ed.
(120) Scuirrer, “ Ueber die Bedeutung des Stenson’schen Versuchs,” Centralbi.

J. d. med, Wiss., 1869.

(121) Senator, “ Apoplectische bulbar paralyse mit Wechselstandiger Empfind-

ungslahmung,” Arch. fiir Psych., Bd. xi., 1881.

(122) Semer.une, “Zur pathologischen Anatomie der pathologischen Kinder-

lahmung,” Arch. fiir Psych., Bd. xxvi Heft i.

(123) Smirn, G. Extior, “A Note on Nervous Lesions produced Mechanically

by Atheromatous Arteries,” Rev. of Neur. and Psych., March 1905,

(124) Smrrn, G. Exxior, “Note on an Anomalous Anastomosis between the

Internal Carotid and Basilar Arteries,” Jowrn. of Anat. and Phys., vol. xliii., 1909.
(125) Smaw, C. G., “Two Cases of Reduplication of the Arteria cerebri

posterior,” Journ. of Anat. and Phys., vol. xliv., 1910.

(126) Sratrenoiz, W., Hand Atlas of Human Anatomy, vol. iii.
(127) Spicer, Hotmes, and Ormerop, 7'rans. Ophth. Soc. U.K., 1896.
(128) Spruizr, W. G., “Bilateral Oculomotorius Palsy from Softening in each

Oculomotorius Nucleus,” Journ. of Nerv. and Ment. Dis., vol. xl., 1914.

(129) Spittzr, W. G., “Symptom-complex of a Lesion of the Uppermost

Portion of the Anterior Spinal and Adjoining Portion of the Vertebral Arteries,”

_ Journ. of Nerv. and Ment. Dis., vol. xxxv., 1908.

(130) Spier, W. G., “A Symptom-complex of Occlusion of the Posterior
Inferior Cerebellar Artery: Two Cases with Necropsy,” Journ. of Nerv. and Ment.
Dis., vol. xxxv., 1908.

131) SprrzKa, quoted by Mitchell and Dercum (98).
132) Starr, M. A., ‘Arterial Sclerosis as a Cause of Nervous Disease,”
Med. Record, vol. \xiv., 1903.

(133) Srewart, R. M., “ Meningo-vascular Syphilis,” Brit. Med. Jowrn., Feb. 27,
1915 (Proc. Med.-Psych. Assoc. of Gt. Brit. and Ireland).

(134) Sroprorp, J. S. B., “A Note on the Significance of certain Anomalies of
the Renal and Spermatic Arteries,” Journ. of Anat, and Phys., vol. xlviii., 1913.

(135) Swanserc, H., ‘The Intervertebral Foramina in Man,” Med. Record,
i, 1915.

(136) TareNnerzky, quoted by Thane (139).

(137) Taytor, E. W., “ Progressive Vagus-glossopharyngeal Paralysis with
Ptosis: a Contribution to the Group of Family Diseases,” Journ. of Nerv. and Ment.
Dis., March 1915.

(138) Taytor, H., “Embolism of Left Vertebral Artery: Paralysis of the
Glossopharyngeal Nerve: Death from Starvation,” Brit. Med. Journ., ii., 1871.

(139) Tuanz, G. D., “ Angeiology,” in Quain’s Anatomy, vol. ii. part ii., 1892.

(140) Tuomas, H. M., “Symptoms following the Occlusion of the Posterior
Inferior Cerebellar Artery,” Journ. of Nerv. and Ment. Dis,, vol. xxxiv., 1907.

(141) Tuomson, H. C., “A Case of Pontine Thrombosis causing Anesthesia of
the Fifth Nerve and Hemianzsthesia of the same side,” Proc. Roy. Soc, Med.,
vol, iii. part ii., 1909-10.

(142) Totpr, Anatomisches Atlas.

(143) Troussgau, “ Lectures on Clinical Medicine,” New Syd. Soe. Lond., vol. i.,
1868.

(144) Turner, W., An Introduction to Human Anatomy, Edin., 1875.

(145) VaLenti, quoted in Poirier and Charpy’s 7'raité @anatomie.

164 The Arteries of the Pons and Medulla Oblongata

(146) Vatenti et v’Atunpo, Inst. Anat. de Pise, 1890.

(147) Vicg v’Azyr, M., 7'raité danatomie et de physiologie, tome i., Paris, 1786.

(148) Watiensera, A., “ Acute Bulbaraffection,” Arch. fiir Psych., vol. xxxiv.,
1901; also Arch. fiir Psych., vol. xxvii., 1895.

(149) WatsHam, W. J., “Arteries, Veins, and Lymphatics,” in A Treatise on
Anatomy, by Morris, 2nd ed.

(150) Weser, L., ‘ Presentation of a Specimen of Occlusion of Basilar Artery,”
Med. News, vol. xlii., 1883 (New York Neur. Soc.).

(151) Weserr, 8S. G., ‘Abnormal Distribution of the Circle of Willis,” Boston
Med. and Surg. Journ., vol. evii., 1882.

(152) Writ, ‘‘ Der Stenson’sche Versuche,” Diss. Strass., 1873.

(153) Wiixs, S., ‘‘ Labie-glosso-laryngeal Paralysis,” Guy's Hosp. Reports,
vol. xxx, 1870.

(154) Wixuramson, R. T., “On the Relation of Spinal Diseases to the Distribution
and Lesions of the Blood-vessels of the Spinal Cord,” Med. Chron., N.S., ii., 1894-5.

(155) Wiuuis, T., Opera omnia.

(156) Winson, S. A. K., “A Case of Thrombosis of the Left Posterior Inferior
Cerebellar Artery,” Proc. Roy. Soc. Med., Neur. Sect., vol. ii. part ii., 1908-9.

(157) Wrinpig, B. C. A., “On the Arteries forming the Circle of Willis,” Jowrn.
of Anat. and Phys., 1887-88.

(158) Woops, “Segmental Distribution of Spinal Root Nucleus of the Tri-
geminal Nerve,” Journ. of Nerv. and Ment. Dis., vol. xl., 1913.

(159) Bourcrry, J. M., Zraité complet de Vanatomie de Vhomme, tome iii.,
Paris, 1844. “

(160) Lewis, B., ‘‘ Arterial System of the Brain,” Brazn, vol. iii., 1880.

‘THE COSTAL MUSCULATURE. By Tuomas Watmstey, M.B.,
Demonstrator of Anatomy, University of Glasgow.

THE rib muscles are differentiated from the other muscles of the thoracic
wall by a group of common characters, structural and functional. They
represent the thoracic continuation of the abdominal muscular sheets, so
that embryologically their derivation is alike; their mode of attachment
to the skeleton is uniform, so that they are solely muscles of respiration ;
their innervation is through the anterior branches of the thoracic nerves;
they have a marked tendency to a state of regression. The regression of
these rib muscles is evident from their structure. The fleshy contracting
part of each fibre is short, and completion is by a long tendinous part,
indicating “the adaptation to a feeble amplitude of movement” (Cleland).
In certain positions the sarcous part of the fibre may have undergone total
regression, and the resulting representative structure is of a fascial nature.
This is an emphasis of the fact that wherever fascia are well marked in
the body, they represent, in major part, muscles (and their sheaths) which
have not entirely lost their function. Possessing the enumerated features
and constituting the costal musculature, there are recognised, in addition to

the diaphragm, the

M.m. serrati posteriores, superior et inferior.
» intereostales, externi et interni.
» levatores costarum.
» subcostalis et supracostalis.
, transversus thoracis.

As the abdominal cavity is held to possess, typically, a muscular wall
of three strata, homologies have been founded for the costal muscles in an
attempt to construct a uniform boundary for the pleuro-peritoneal cavity.
But while many of the homologies are definitely established, others are
still in dispute For example, some authors consider the subcostalis as
part of the “internal oblique sheet” (Cunningham, Le Double); by others
it is placed as part of a deeper sheet and in series with the transversus
abdominis (Henle, Testut). The following is a contribution towards the
establishment of a fuller homology of the costal musculature, and is
founded on the demonstration of the compound morphology of the
“internal intercostal muscles.” !

1 The consideration of the endothoracic fascia will form the subject of a future article.

166 Mr Thomas Walmsley

As described for the adult human subject, the relation of the completely
costal members of the anterior thoracic nerves to the “internal intercostal
muscles” is that, while posteriorly they are superficially placed, anteriorly
they are deep to these muscles, the passage through the muscle being
prolonged over some distance (fig. 1). The abdominal intercostal nerves
seek a corresponding plane in their “ perforation of the intercostalis in-
ternus” to run between the internal oblique and the transversalis
abdominis muscles. The deep relation of the intercostal nerves in that
part of their course deep to the “internal intercostal muscles” has been
continuously described as the costal pleura. The branches of the lumbar

Fic. 1.— Diagrammatic representation of the thoracic
wall as presently described.
E.C., external intercostal muscle; I.C., internal intercostal muscle ;
A.I.C., anterior intercostal membrane ; P.I.C., posterior inter-

costal membrane ; ‘I’. T., transversalis thoracis muscle; N., inter-
costal nerve ; P., costal pleura.

plexus in series with the intercostal nerves, on the other hand, are not
superficial to the internal oblique muscle till their final perforation of
this layer, which is described as homologous with the “ internal intercostal
muscles.” The double relationship of the nerve to the muscle, then, is
peculiar to the thoracic region, and is such that the muscle may be con-
sidered, in relation to the nerve, as of two parts, a posterior portion and
an anterior portion, the former being more deeply placed in the thoracic
wall. Now, it is known that the origin of the “internal intercostal muscle ”
from the costal margin differs at different points throughout its length.
Souligoux has demonstrated that posteriorly the muscle arises from
the inner lip of the costal groove, but anteriorly the origin is from both

The Costal Musculature 167

the inner and outer lips of that gutter; further, that “the change in the
position of the nerve” takes place at the doubling of the muscle. Careful
dissection, however, of the “internal intercostal series” has shown that
here we are really dealing with two distinct sets of muscles belonging to
different tissue planes; that the fusion of these two sets into one as
the “ internal intercostal muscle” of each space is only an apparent fusion,
for throughout their whole contiguous length they are separated by fascial
tissue and by the intercostal nerve. The following dissections were carried

Viii.

st ELC.

seek ALL.

Fic. 2.—To show, muscle fibres replacing the anterior
intercostal membrane.

A.1.C., in proximity to the interchondral joints ; E.C., external
intercostal muscle ; I.C., internal intercostal muscle ; A.L.,
anterior capsular fibres of the interchondral articulation.

out on ordinary dissecting-room subjects. The sternum and vertebral
column were sectioned longitudinally, and each half of the chest wall was
treated separately." 3

1. Examination of the Superficial Surface of the Chest Wall—The
external intercostal muscles were first exposed. They commence posteriorly
in the region of the tubercles of the ribs and extend forwards to about
the costal cartilages. Passing between successive ribs, the origin and the
insertion of these muscles are on the lateral surfaces of the opposing

It is pro to leave for future consideration the relation of the disposition of
contractile muscle fibre to function.

168 Mr Thomas Walmsley

borders. In their anterior extension the muscle fibres gradually diminish
in amount and the anterior intercostal membrane continues forwards the
tissue plane. This membrane reaches the external margin in the upper
spaces, but lower down it does not extend beyond the final fusion of the
bounding cartilages, and in this region, 6th to 9th interspaces, muscle
fibres are occasionally representative, especially in proximity to the inter-
chondral articulations (fig. 2). While the membrane is loosely connected
to the capsule of these joints, it does not form the anterior part of the
capsule, nor is it in any way specifically interrupted at these positions.
In the 10th and 11th interspaces the intercostal muscles extend forwards

: TUBERCLE.

ian NY

en T. COSTO-TRaNs,

ulin 1 LG.

we.

oy “254° ANT. COSTO-TRANS.
: LIG.

Fic. 3.-—In the lower space the external sheet of the thoracic musculature has been
reflected. The muscle called the ‘‘internal intercostal” will be noted as deep to
the posterior intercostal membrane. (In the B.N.A. terminology the post. costo-
trans. lig. is the lig. tuberculi coste, and the ant. costo-trans. lig. is the anterior
part of the costo-transverse lig. ) ;

deep to the posterior border of the corresponding digitation of the external
oblique muscle of the abdominal wall, and a membrane of delicate structure
continues the muscle anteriorly between the external and internal oblique
muscles, and finally fuses with the aponeurosis of the latter muscle.
Posteriorly the levatores costarum (long. et brev.) are in series with the
external intercostals. The supracostalis, extending from the first rib over
two or three spaces, may or may not be present, but is also a derivative
of this sheet. This layer of the costal musculature, then, comprising the
levatores costarum, the external intercostals, and the anterior intercostal
membranes and the supracostalis, forms a complete external sheet from the
vertebral column to the sternum, and is homologous with the external
oblique muscle of the abdominal wall. :

The Costal Musculature 169

ap Reflection of the External Sheet in the Whole of its Extent and
Definition of the Anterior Parts of the Costo-transverse Ligaments.—
Nowhere are the intercostal nerves yet exposed. At the vertebral extremity
of each space the posterior intercostal membrane is shown as a strong
fascial layer which, towards the median plane, fuses with the anterior part
of the costo-transverse ligament (fig. 3). Passing forwards in each space,
this membrane becomes continuous with a layer of muscle tissue which,
like the membrane, has its origin from the lateral lip of the costal groove.
This muscle sheet, commencing as a thin layer about the mid length of each
space, gradually increases in volume and, retaining throughout the original
superficial relationship to the intercostal nerve, reaches, in the upper spaces,
the sternal margin (fig. 4). In the lower intercostal spaces the anterior ex-

Fic. 4.—Dissection of the sternal end of the 3rd intercostal space.

N., intercostal nerve; E.C., external intercostal muscle; T.T., intra-
costal membrane ; P., pleura ; P.M., pectoralis major.

tension of the muscular tissue is interrupted at the interchondral articula-
tions, and the anterior fibres of the capsules of those joints have the same
direction as the fibres of the muscle (fig. 2). In the 10th and 11th spaces
the internal oblique muscle of the abdominal wall is directly continuous
with the anterior portions of these intercostal muscles. The second layer,
then, of the thoracic wall musculature is composed of the posterior inter-
costal membranes and the anterior parts of the “intercostales interni”
muscles, and it arises throughout its whole length from the lateral lip of
the subcostal groove and is entirely superficial to the intercostal nerves.

3. Examination of the Deep Surface of the Chest Wall.—The costal
pleura and the extra-pleural fat were removed; it was noted that the fat
is accumulated on the rib surfaces and is absent over the muscular tissue.
The transversus thoracis muscle is seen to conceal the terminal portions
of the upper intercostal nerves. When traced laterally this muscle becomes

170 Mr Thomas Walmsley

continuous with a fascial layer of varying density, through which the
intercostal nerves are visible (fig. 5). In all cases, however, the fascia is
strong enough to allow of reflection, and will be found attached to the
inner surfaces of contiguous ribs. At its commencement the fascia is
striated in series with the parent muscle, and in a few cases a similar
disposition of actual fleshy fibres will be found (Camper, Tarin). Continued
laterally, the fascial fibres give place to muscular fibres, which also have their
attachments on the medial surfaces of the bounding ribs. Commencing about
mid-way in each space, this muscle sheet increases in volume and extends
backwards deep to the posterior intercostal membrane, where it forms the
subcostalis by passing over one or more ribs, and is continued as fascia or
as muscle (Macalister) from about the angles of the ribs to the vertebral

Fic. 5.—In the lower space the intracostal muscle and the fascia
extending to the vertebral column has been reflected, thus
exposing the intercostal nerve lying on the internal inter-
costal muscle and the posterior intercostal membrane.

column. In the 10th and 11th spaces it is possible to trace the transversalis
abdominis as a fascial layer, in contact with the pleura, posteriorly to
become muscular tissue disposed as in the upper spaces. Here we are
dealing with the third layer of the thoracic musculature, throughout its
whole length deep to the intercostal nerves. It comprises the transversus
thoracis muscle, a layer of fascia in loose contact with the pleura derived
from that muscle and from the transversus abdominis, the posterior parts
of the “internal intercostal” muscles, and the subcostal muscle.

The “internal intercostal” muscle of each space, then, consists of two
parts, morphologically distinct. The anterior portion is the more superficial,
belongs to the internal oblique sheet, and is properly termed. the internal
intercostal muscle. It arises from the lateral lip of the costal groove, and
is inserted into the upper border of the rib below, the striation being down-

The Costal Musculature 171

wards and backwards. It is confined to the anterior two-thirds of each
intercostal space. The posterior portion of the double muscle is in the
plane of the transversalis sheet, and is hereinafter termed the intracostalis.
It arises from the medial lip of the costal groove, and is inserted into the
upper border and the medial surface of the succeeding rib, the striation
again being downwards and backwards. The intracostal muscle is present
in about the middle two-fourths of each space, and where it is contiguous
with the internal intercostal muscle apposition has been described as fusion.

(tins Lata See

«fe
rt eas
ee

ee

7.7

Fic. 6.—Diagram of the thoracic wall as reconstructed.

L.C., levator cost ; I.T.C., intracostal muscle ; 8.C., sub-
costalis ; I.T.M., intracostal membrane ; N., nerve.

The thoracic wall musculature, therefore, consists of three distinct
layers (fig. 6):
A. External layer. Oe Birks costarum, intercostales externi and the
anterior intercostal membranes, supracostalis, and the serrati.
B. Middle layer.—Intercostales interni and the posterior intercostal
membranes.
C. Internal layer.—Transversus thoracis, intracostalis, and the intra-
costal membrane, and the subcostalis.
These layers are each homologous with the corresponding layer of the
abdominal wall, and the intercostal nerves preserve the typical relationship
to the muscular strata.

THE TRANSITION OF THE CILIATED EPITHELIUM OF THE
NOSE INTO THE SQUAMOUS EPITHELIUM OF THE
PHARYNX. By W. Souter Bryant, A.M., M.D.

In an effort to determine the boundary lines between the squamous
epithelium and the ciliated epithelium of the rhinopharynx, an examination
was made of the rhinopharynges in the domestic rabbit, eight individuals ;

Fic. 1.—Human pharynx, adult.

The intermediate epithelial band (represented by blue area) extends forward
on the back wall to near the septum and backward nearly to the angle of the
rhinopharynx. The band passes over the Eustachian tube and inclines back-
ward at the union of the soft palate with the lateral wall. The band then
inclines forward to a point near the basal septum of the floor of the rhinopharynx.

in the guinea-pig, three individuals; in the domestic cat, four individuals ;
in the macacus and cebus monkeys, one each; and in man, twelve indi-
viduals—adults, children, infants, and fcetus. The search for these boundary
lines demonstrated the presence of a third variety of epithelium (mentioned
by von Ebner), which, in the character of its cells, is intermediate between
the squamous cells and the ciliated columnar cells. This epithelium, which
occupies the transitional zone between the epithelium of the oropharynx
and that of the nasal fossz, is composed of cuboid cells with imperfect
cilia or no cilia at all.

In all the specimens examined, the squamous epithelium extends as

Transition of Rhinopharyngeal Ciliated into Squamous Epithelium 173

far-forward as the fosse of Rosenmiiller. The intermediate zone of the
epithelium occupies the region of the orifice of the Eustachian tubes, while

Fic. 2.—Human feetus at term.
The band of intermediate epithelium extends a little further back than in the adult.

— S ine “ |
¥ ae, 4,
os “pom \} \
Y + %
fi j yy)
. Fic, 3.—Macacus monkey.
The band of intermediate epithelium lies behind the Eustachian orifice.

the ciliated columnar epithelium extends a variable distance backward,
approaching the Eustachian tubes.
The intermediate zone of the epithelium lies in a wavy ring around the

174 Dr W. Sohier Bryant

naso-rhinopharynx. It bends forward on the anterior and the posterior
walls, and backward on the lateral walls at the attachment of the posterior

Mill

Wh << :

Fic. 4.—Cebus monkey.
The band of intermediate epithelium lies behind the Eustachian orifice.

Fic. 5.—Domestic cat.
The band of intermediate epithelium lies behind the Eustachian orifice.

faucial pillars. The zone includes interdigitations and islands of the
neighbouring varieties of epithelium.
The boundaries of the intermediate zone of epithelium vary in position,

HEREDITARY ABNORMAL SEGMENTATION OF THE INDEX
AND MIDDLE FINGERS. By H. Drinkwater, M.D., M.R.C:S.
(Eng.), F.LS.

THE hands referred to in this communication show several peculiarities, the
most striking being a marked reduction in the length of the index and
middle fingers, so that the ring finger projects far beyond the others

Fie, 1.

(see figs. 1 and 2). Both hands are similarly affected. This condition
is known to have been hereditary through at least four generations,
but it has not been possible to trace it further back. The pedigree is
shown in fig. 3.

The two fingers referred to remind one of the digits in brachydactyly,
but there all the fingers are affected.’

1 “An Account of a Brachydactylous Family,” by H. Drinkwater, Proc. Roy. Soe.

Edin., vol. xxviii., part i. (1907), and “A Second Brachydactylous Family,” by the same
author, Journ. of Genetics, April 1915.

178 Dr H. Drinkwater

The radiographs show certain features which do not seem to have been

recorded previously. Fig. 4 is the radiograph of the hands of a girl aged
nineteen (No. 9 in the chart).

Fic. 2.

It shows: (1) An abortive condition of the middle phalanx in each
finger, which is seen to be reduced to about one-third its normal length.

3 21
| |
| | | | oe
9 23 24 96 9
et ek. | |
BS ee ee eae Pies Fie Sh GS ees a
eT ee ope ae A oe
©’ OQeshessse@eee
§ 5 2
~~ “1-12 13 14 16-16

Fic. 3.—The family pedigree.

$6 = normal male.

? = normal female.
é = abnormal ,,

¢ = abnormal ,,

This is the one essential feature of brachydactyly. The hands are
therefore brachydactylous.

Hereditary Abnormal Segmentation of Index and Middle Fimgers 179

(2) The proximal phalanx in the ring finger is abnormally long.

(3) The base of the proximal phalanx of the index finger is very oblique
(normally it is at right angles to the length of the bone). (Fig. 13; No. 6
in chart.)

(4) The proximal phalanx of the middle finger appears to be divided
into two in the middle of its length. This was the first radiograph which
I procured, and if certain others had not been forthcoming it would
have been impossible to account for the very striking peculiarities just
enumerated—namely, the oblique base of the proximal phalanx in the

Fic, 4.

index finger, and the two bones in place of the normal one (proximal
phalanx) in the middle finger.

THE PROXIMAL PHALANX OF THE MIDDLE FINGER.

In No. 9 (fig. 4) this appears to be divided in the middle transversely.
A precisely similar condition is present in No. 7 (fig. 5), but in No. 11
(fig. 6) the division is much nearer the base, whilst in No. 15 it is nearer
the distal end of the bone.

In the younger individuals the bones are not fully ossified, and the
epiphyses are not yet ankylosed. They help to elucidate the nature of
the abnormality.

180 Dr H. Drinkwater

Fie. 5.

Fie. 6,

Hereditary Abnormal Segmentation of Index and Middle Fingers 181

In No. 12, a boy aged thirteen (figs. 1, 7,and 8), the middle finger shows
the following bones, counting from the distal extremity :—

! The shaft of the distal phalanx.
— 2 its epiphysis.
3 The abortive middle phalanx without any
epiphysis.
q A longer bone than 3, with rounded head.

& A bone of approximately the same length
as 4. Next to this is seen the head

Fic. 7. (epiphysis) of the metacarpal bone.

Fie. 8.

A normal hand shows a single bone in place of 4 and 5, of about their
combined length; with a thin plate-like bone (the epiphysis) at the base,
(like 2) before ankylosis has occurred.

182 Dr H. Drinkwater

The conclusion is perhaps justifiable that the normal phalanx has
become divided into two approximately equal portions. This also is the
conclusion one would come to from an examination of the hand of No. 9.
It is, however, practically certain that this would be an erroneous
interpretation.

What then is the nature (homology) of these two bones marked 4 and
5? Is 5 the lower half of the shaft, or is it an overgrown epiphysis, or
something else? I will endeavour to answer these questions later on.

The axis of 5 is not in line with the axis of 4, as one would expect
if they both belonged to the shaft.

THE PROXIMAL PHALANX OF THE INDEX FINGER.

In every abnormal individual in this family the radiographs show this
bone to have an oblique base.

In fig. 11 (boy aged nine years) what appears to be the epiphysis is a
triangular bone, and it is obvious that after ankylosis has occurred the
base will be oblique as in all adult abnormal members of the family. But
is it the epiphysis ?

Let us now look again at No. 12 (figs. 8 and 9), and trace the bones in ~
the index, as was done in the middle finger. It shows :—

/ The shaft of the terminal phalanx.

2. Its epiphysis.

3 The abortive middle phalanx.

q <A thin plate which is to form the “head” of
5

=
aa
the proximal phalanx.
The shaft of the proximal phalanx.
6 Its epiphysis.

7 A triangular bone interposed between 6 and

x the head (epiphysis) of the metacarpal

bone.
Fic. 9.

This triangular bone is so placed that the finger is tilted away from the
thumb, and when ankylosis occurs the base of the proximal phalanx will
have an oblique direction. There is no doubt that the obliquity of the base
seen in this phalanx in the adult hands is due to the presence of a similar

Hereditary Abnormal Segmentation of Index and Middle Fingers 183

triangular bone which has become ankylosed with the shaft of the proximal
phalanx and forms its basal position. In those cases where this triangular
bone is the only one present on the proximal side of the shaft, it would
appear that the epiphysis is absent.

What is this triangular bone? The only interpretation which seems
warranted by a study of this series of radiographs is that it is an extra
bone—one which is not present in the normal hand.

It is probably due to an abnormal segmentation of the row of meso-
blastic cells which form the primitive basis for the osseous skeleton of the
digit. It may, however, be due to an intrusion of surrounding cells, and
this might explain the triangular shape, which one would not expect to see

ee efriel We, oetly ehberiern
J outed phere ot Ue Leocelal
te Gaterclay where J covlel ariive
et ts 06 2:50 crhechecs henee’
suoelel Fe roost converters 40 0
yourtey tet SI corelel nracege fo

Fic. 10.—Specimen of the handwriting of No. 7 (fig. 5).

resulting from a transverse segmentation. Though from the data to hand
it is impossible to speak dogmatically, an abnormal segmentation seems the
most likely explanation.

We can perhaps now speak more positively about the peculiarity seen
in the middle finger. I conclude that the bone marked 5 in figs. 7 and 8
is homologous with the triangular bone in the index finger, for the
following reasons :—

1. It is not, as one would expect it to be, in line with 4, which is
undoubtedly the shaft of the proximal phalanx.

2. In several cases it is seen to have the same triangular “cocked hat”
shape (fig. 11).

3. In fig. 6 (No. 11) one can see the dark line about } inch from the
base of the phalanx indicating the union of the epiphysis with the shaft—
i.e. the basal attached portion is the epiphysis, so that the separate bone
below this is an extra piece.

184 Dr H. Drinkwater

Fie. 11.

Fig, 12.

Hereditary Abnormal Segmentation of Index and Middle Fingers 185

Fic. 13.

186 Hereditary Abnormal Segmentation of Index and Middle Fingers

4. In several adults, when ossification is complete there is a distinct
thickening in the place of union of this extra portion with the true
phalanx (fig. 12). Thus there seems to be an extra bone in the index and
middle fingers.

The feet show ordinary brachydactyly.

This family is an illustration of Mendelian inheritance. The condition
is due to some mendelising factor. It is not transmitted by the normal
members of the family.

There are 36 descendants of the abnormal members of the family, and
of these 15 show the abnormality. Most of the males are labourers; one
(No. 7, fig. 5) is a clerk, and writes an excellent script (fig. 10).

No. 6 married a normal cousin.

One radiograph (fig. 4) was taken by Dr J. Elliott of Chester; all the
others were taken by Dr Geoffrey Williams of Wrexham. To both of
these gentlemen I wish to express my indebtedness and gratitude for their
indispensable share in the work.

See
—

THE MEASUREMENT OF DIAPHYSIAL GROWTH IN PROXIMAL

AND DISTAL DIRECTIONS. By Kenetm H. Dicsy, M.B.,
F.R.C.S., Professor of Anatomy, University of Hong-Kong.

THE nutrient foramen of the shaft of a long bone transmits the vessels
which provide blood for the ossifying cartilage during growth, for the
resulting bone, and later for the medulla. The original artery which
accompanies the initial invasion of the primitive cartilaginous rod by
osteoclasts and osteoblasts enlarges and persists as the nutrient artery.
Bone is deposited round the vessel, thus forming a permanent track which
_ traverses the compact tissue in a most oblique direction for from one-half
to two inches and more, according to the particular bone. The nutrient
foramen in the adult is only the external opening of the nutrient canal.

It follows from its manner of formation that the nutrient canal always
points towards the oldest part of the shaft of a long bone. It is more
accurate to say that the canal points towards the site which the oldest part
of the bone would occupy were it not that the osseous tissue first formed is
subsequently absorbed in providing the medullary cavity. Indeed, but
for this absorption the bottom of the canal would be formed by the very
earliest deposit of bone.

If the various long bones of the body are sawn longitudinally so that
the nutrient canal lies in the plane of division, the initial point of ossifica-
tion may be easily determined, for it corresponds to that point in the centre
of the medullary cavity which is reached by an imaginary prolongation of
the nutrient canal. The site of initial ossification having been determined,
it becomes easy to measure the precise lengths of bone which are formed
from the two growing ends of the diaphysis.

The result of such an examination of the principal long bones of the
human body is as follows :—

Formed from Proximal Formed from Distal End

End of Diaphysis. of Diaphysis. ~
Name of Bone. . : :

F Proportion ; Proportion

sr ge Whole Length in | of Whole

ree Diaphysis. Diaphysis.

per cent. per cent.
Femur . ; P 5 | 31 ll 69
Tibia : : ; 74 | 57 58 43

Fibula. ; ‘ 74 ' 60 5 40 *

Clavicle . : 34 62 2 38
Humerus ; ‘ 94 81 24 19
Radius . ’ : 2 25 6 75
Ulna : ‘ : 1} / 19 7§ 81

188 The Measurement of Diaphysial Growth

NOotEs.

1. These bones were taken from different bodies. A thorough examina-
tion of a large series of each bone is desirable to provide reliable averages.

2. It is generally assumed that the obliquity of the nutrient canal results
from the fact that whilst a bone grows in length chiefly from one end, the
vessel, from which the nutrient artery springs, grows equally throughout its —

FEMUR AB = 5 wwenes BC = tI wenes

TIBIA AB = 7} ienes B C= 5% incnes

FIBULA AB = 7% incnes 8B C=5 iwenes
Td

HUMERUS AB= vai INCHES BC =2: wwenes

RADIUS A B=2 uncnes 8B C=6 uwnenes

ec
en 28 H
, '
ULNA A B=12 wenes B C= 7% inecnes
5 28
: re
'
CLAVICLE (Not figured) A B=3} incnes 8B C=2 uncnes

Tracings of longitudinal bone sections.
A, upper end of diaphysis ; B, initial site of ossification ; C, lower end of diaphysis.

length. Relative changes in the position of the proximal end of the artery,
however, might also be a factor in determining the degree of obliquity.
But, anyway, the canal leads inwards to the initial site of ossification.

That this is so is confirmed by the presence of the nutrient foramina in
very young bones—before the fourth month of foetal life; and also in the
case of the adult femur where, when two foramina are present (as not infre-
quently happens), the nutrient canals have different obliquities, so that when
prolonged they converge on almost the same point in the medullary cavity.

_——«<T aT Pe h

a a

ee
_ v Md

THE GENITALIA OF GALEOPITHECUS. By FrepERIc Woop JonEs,
D.Se., Professor of Anatomy, University of London, London School
of Medicine for Women.

THE species I have examined is that which inhabits the Malayan Islands
and is generally known as (Galeopithecus volans (for nomenclature and
specific characters see Waterhouse, G. R. (1) and Gray, J. E. (2)). It
is that commonly known by the native name “Colugo” in the Straits
Settlements (for further details see Dennys, N. B. (3)), and, according
to Charles Hose (4), as “ Kubang plandok ” in the Baram district of Borneo.
This Bornean term is a curious one, since “kubang” is also the native
name for the flying squirrels of the genus Pteromys (although in strict
Malay it signifies a wallow pool), and “plandok” is the native name for
the mouse-deer of the genus Tragulus. It would seem that even to the
Malay the animal is somewhat of a zoological puzzle.

MATERIAL.

I have had the opportunity of examining one adult male, one adult
female, and one young female. These were all spirit specimens in an
excellent state of preservation; they were collected by Dr Charles Hose
in the Baram River district of Borneo (see 4), and were placed at my
disposal by the kindness of Professor G. Elliot Smith. The genitalia of
the male after examination, and subsequent exhibition at the Arris and
Gale lectures in 1914, were preserved as a specimen, since added to the
collection of the Museum of the Royal College of Surgeons.

REPRODUCTION.

Concerning the breeding habits but little seems to be recorded. Wallace
has noted some interesting points regarding the young (5): “It is said
to have a single young one at a ‘time, and my own observation confirms
this statement, for I once shot a female, with a very small blind and naked
little creature clinging closely to its breast, which was quite bare and
much wrinkled, reminding me of the young of Marsupials, to which it
seemed to form a transition.” Dr Cantor has added some more details
in his account of Malayan animals (6); for he says: “Of a number of
females with young, none had more than one offspring, which was carried

190 Professor Frederic Wood Jones

wrapped in the wide mantle-like membrane.” It is possible that Wallace’s
idea that there was a reminiscence of marsupial conditions in this single
offspring may not be so fanciful as it, at first sight, appears to be. It
seems certain that the young is born in a very immature condition, and
that at any rate a functional imitation of the marsupial physiology is
present, the membrane recess forming a false marsupium for the reception
of the premature young.

REPRODUCTIVE SYSTEM.

Most features of the reproductive system have been previously described
in detail, and there is no novelty nor originality in the record I have made
of the condition present in these animals; but I have undertaken this
re-examination as part of an ordered study of the genitalia, not only of
Galeopithecus but of its probable kindred.

By far the best account of the anatomy of Galeopithecus is to be
found in the well-known monograph of Wilhelm Leche (7). It is
true that the genitalia do not here receive quite so much detailed
attention as is devoted to some of the other systems; nevertheless there
is but little to add to this account, which was written thirty years
ago. The work of Chapman (8) carries the description of the genitalia
but little beyond the results arrived at by Leche. Chapman examined
one male spirit specimen from the Baram River district of Borneo,
and subsequently the viscera of another male from Sumatra; no female
was dissected or examined. Although for most details the work of
Leche is quoted by Chapman, his conclusions are in some _ respects
independent, and will be referred to later. Leche has fully described the
internal genitalia of the female, and has figured the condition of the
Miillerian ducts in two specimens he examined.

The adult female which I have dissected differed in no way from the
description given by Leche, save in those details which obviously depend
upon the fact that in this specimen there has been a recent pregnancy.
The two uteri are entirely separate, and each opens by a separate orifice
upon an elevation which projects into the vaginal lumen after the manner
of the human portio vaginalis of the cervix (see fig. 1). The walls of the
uteri are thick in my specimen, and thé mucous membrane is spongy; in
the larger left uterus was some débris, partly adherent to the uterine wall,
which probably marked the placental site. The uteri are roughly
pyriform, tapering towards the vaginal opening, and they are situated
one upon each side of the rectum behind the bladder. The left uterus
in my specimen measures 28 mm. in its long axis, and it is double the
length and considerably more than double the size of its fellow. The

The Genitalia of Galeopithecus 191

-Falloppian tubes are narrow and tortuous, winding round the medial and
cephalic aspects of the small elongated ovary. Upon the right (non-
pregnant) side the Falloppian tube joins the apex of the uterus; but upon
the left (pregnant) side the enlargement of the uterus has taken place
to some extent above the insertion of the tube, and the tube therefore

Fic. 1.—Internal genitalia of the female.

A, new-born female (Zool. Mus., Leiden), from Leche, plate vy. fig. 41. B, adult female. from

Leche, plate v. fig. 40. C, adult female, probably recently pregnant. D, pregnant female

bat (Cynonycteris amplexicaudata), from Robin, plate vii. fig. 47.
enters the uterine cavity some distance below its apex. The vagina is
a wide cavity; its walls are extremely thin, and its lining membrane is
glistening. I find no folds upon the vaginal wall such as are described
by Leche, and I imagine it is possible that they disappear after pregnancy.
The urethra opens just within the vulva, and there is therefore practically
no urogenital sinus proper in the female.

Leche has described and figured the external genitalia of the adult
VOL. L, (THIRD SER, VOL. XI.)—JAN. 1916. 13

192 Professor Frederic Wood Jones

female, and Gervais has figured the condition present in the young (see 9).
Leche’s figure does not appear to me to be satisfactory in all respects,
and I have ventured to give a new illustration of the details of the external
genitalia as they are present in the adult specimen I have had the
opportunity of dissecting (see fig. 3). The figure given by Gervais,
however, represents exactly the condition present in my young example,
and I have only thought it worth while to furnish an illustration of this
specimen since it shows some of the debated points in the anatomy of the
young Galeopithecus to which, so far as lam aware, Professor W. K. Parker
was the first to call attention (see fig. 2).

In the young female the genital orifice is almost slit-like, the long axis
of the opening being in the long axis of the body. The lateral margins
of this slit form two slight folds, meeting in front and diverging slightly
behind where the orifice becomes more widely opened. The cephalic meet-
ing of these folds marks the site of the tip of the genital tubercle, and they
are therefore to be regarded as the inner genital folds or labia minora. It
would be difficult, or impossible, from this specimen, or from any of the
material that I have examined, to determine exactly what was the anatomical
representative of the outer genital folds. A very much earlier stage of
development is needed for following the fate of these structures. Fortunately,
the very point in which Galeopithecus shows a somewhat anomalous form
of development is found very exactly paralleled in other animals of which
it is possible to examine a series of younger stages. To this point I will
return, and, passing over the evidence for the present, will homologise as
outer genital folds those curious skin folds which, running from the sides
of the genital orifice, surround the anus and, leaving it at the bottom of a
deep pocket, meet behind upon the base of the tail.

In the adult several changes have taken place. The genital tubercle
and its associated labia minora have enlarged considerably, and with this
enlargement there has proceeded a most marked flattening of the parts in
an antero-posterior direction: The clitoris and its folds become almost leaf-
like, and they constitute one of the striking features of the genitalia of
Galeopithecus, for they shut down over the genital orifice as a sort of flap
which closes the rather capacious vulva. In the illustration of the parts
I have figured this flap as raised up from the vulval orifice. It is the
presence of this structure which makes the outlet of the adult female
genitalia appear to be more or less transverse to the long axis of the body.
The labia minora are not confined to the free portion of the clitoris which
forms the flap, but they pass backwards as rather inconspicuous folds about
half way along the vulval outlet. It is worthy of note that the clitoris,
although it is broadened and flattened as I have described, is perforate ; in

The Genitalia of Galeopithecus 193

Fic. 2.—Young female (natural size), showing external genitalia and suprapubic skin folds.

194 Professor Frederic Wood Jones

my specimen a probe could be passed into the canal for a distance of some
7 mm., but this canal does not communicate with the urinary tract, and ends
blindly. I do not follow Leche in regarding this pocket merely as a recess
of the preputium clitoridis, although the preputium provides an ample
hood for the clitoris, nor do I find in my specimen an anatomical condition
of the clitoris exactly similar to that which he describes. Although in

i,

| |
ANI
yy
|
|
y

Fre. 3.—External genitalia, adult female.

Galeopithecus this blindly-ending canal of the clitoris is conspicuous, the
animal is not peculiar in its possession, for it represents a common embryonic
and a not uncommon adult phase in certain animals. The urethra opens at
a patulous orifice just within the vulval cleft upon the anterior wall of the
terminal portion of the vagina.

The internal genitalia of the male possess no very noteworthy features ;
Cowper’s glands are present, and are, as Leche has noted, in every way
similar to those seen in the Chiroptera and the Insectivora generally.

The Genitalia of Galeopithecus 195

___'The-male external genitalia are, however, very peculiar, and I have

figured the condition present in my specimen, since Leche gives no figure
of the undissected parts (see fig. 4). The testes are external, and carried
in a scrotum suspended from the region of the root of the penis in advance
of the anal opening. From the scrotal areas the curious folds which en-
circle the capacious anal pocket are continuous. This anal pocket of the
male is deep and wide; it constitutes a very curious skin-lined pouch, the
anus being situated deeply within the pouch and completely hidden from

| TN

Wilt

Fie, 4,—External genitalia, adult male.

view in the natural condition of the parts. What may be the functional
purpose of this pouch I do not know; it is rather better developed in my
male specimen than in the female, although it is a very striking feature in
both sexes. It is lined by short fine fur, is evidently capable of contraction
and expansion, and is quite unsoiled by intestinal contents in my specimens.
The hinder parts of the scrotal areas invade the anterior portions of
the pouch.

The penis is pendulous, and is marked by a median raphé which passes
back between the two halves of the scrotum and, entering the pouch, dis-
appears in the neighbourhood of the anterior margin of the anus. The

196 Professor Frederic Wood Jones

glans of the penis is not simple, but is best described as being trilobed ;
the median portion, perforated by the urethra, forming the bulk of
the glans; the lateral lobes constituting spur-like processes of the main
portion. The penis is provided with a suspensory ligament, and its
muscles—the ischio-cavernosus, pubo-cavernosus, and bulbo-cavernosus—
are well developed, and require no special description; there is a
conspicuous m. retractor preputialis which obtains a bony origin from
the public rami.

THE PossIBLE DERIVATION AND AFFINITIES OF THIS TYPE
OF GENITALIA.

Galeopithecus being such an anomalous animal in most respects, has been
subjected to analysis by many zoologists in the hope that by some resolu-
tion of its systems and organs its true affinities could be determined.
Leche has conducted such an analysis for the reproductive system, and his
results may be summed up by saying that he finds genital affinities with
lemurs (Chiromys and Tarsius), with Tupaia, with the Insectivora, and
with Chiroptera. Chapman (8, p. 251) concludes that the external
genitalia show most resemblance to those of the lemurs.

Without criticising this analysis, I will take the outstanding features
of the genitalia of Galeopithecus and attempt to determine their nearest
likenesses among possible allies.

The uterine condition of Galeopithecus finds its exact parallel in certain
members of the Chiroptera. The work of Robin (see 10) furnishes several
examples of double uteri in bats which show conditions in all respects
identical with that described in Galeopithecus. It is to this source of
information that Leche has turned, and I agree with him in selecting
Cynonycteris anplexicaudata as the most exact parallel. The condition
of the cervix uteri in this animal is especially striking in its similarity to
that of Galeopithecus; Robin has figured the genitalia of this animal with
one uterus pregnant, and I have thought it worth while to reproduce a
drawing of his figure along with the figures of Galeopithecus (see fig. 1).
The shortness or comparative absence of the urogenital canal is also a
feature present in most bats as well as in animals higher in the scale.

As for the external genitalia, it is easy to determine that, with all their
peculiarities, they have followed in their development that type which in
previous papers I have designated cloaca explicata. In this, although they
fall into line with Tupaia and with the lemurs, they are also like
Chiroptera, and it is certainly to the bats that their resemblance is most —
marked. In the apparent transverse opening of the vulva they have their
parallel in the Megachiroptera; the curious flattened clitoris is also found

The Genitalia of Galeopithecus 197

. ~the bats, and a terminal perforation of the clitoris I have
_ previously demonstrated in the young of Myotis nigricans. The male

Fic, 5.—Probable derivation of type of external genitalia.

early phase of mammalian . B, fetal stage of female
she c, Sutel taaae ot wale bat. Tee Galeopithecus. B male

__ shows affinities with the Chiroptera in the form of the glans penis, which is
found again in a somewhat modified way in many members of the order
(see Robin, op. cit., plates 5 and 6, ete.).

It is, however, when we take the whole form of the external genitalia,

198 Professor Frederic Wood Jones

and especially that curious skin fold which surrounds the anal orifice, that
the resemblance to the Chiroptera becomes most striking; indeed, so far as
I know, the only real approach to this condition is seen in the bats, and
that only in the fcetal stages. The posterior portions of the cloacal margins
are extremely prominent folds in the embryos of many bats, though in
only a few—such as Taphozws—do they persist into the adult as anything
comparable to the anal pouch of Galeopithecus. I have embryos of one
bat (species not determined yet) in which the likeness to Galeopithecus is
perfect in all respects, an anal pouch being present in both sexes, but
especially in the male, which is proportionately as well developed as is the
adult pouch of Galeopithecus.

I have figured a probable course for the development of the genitalia of
Galeopithecus, and for the intermediate stage I have taken a common
phase seen in bat embryos; the final stage as I have represented it might
serve either for the adult of Galeopithecus or for the embryo of certain
bats, the only point of difference being that I have represented the testes
as descended (see fig. 5).

THE MAMMARY GLANDS.

There appears to be some uncertainty about the actual state of mammary
development, for there are considerable discrepancies in the published
accounts given by different authors. It is possible that the animal shows
some individual variation in this respect, for the adult female that I have
examined does not conform exactly to any of the published descriptions.
In most works upon zoology the account as given by Dr Gray is quoted.
According to Gray (see 2), “the teats are placed in pairs on a large gland.”
This is practically identical with the description as given by Leche; but
Cantor takes a different view of the structure, for he says (6) “there are
four mammee situated in pairs one above the other, close to the axilla.”

In the adult female that I have examined the mammary glands were
evidently in a state of functional activity. The mamme are large and
somewhat pendulous; they are situated in the pectoral region towards
the anterior margin of the axilla, the mass of the gland and the nipple
being retained in the axillary space between the chest wall and the
redundant skin fold that constitutes the parachute membrane. The skin
over the gland is fine, it is not covered by the general body hair, and the
whole breast is apparently of a pinkish flesh colour. The whole structure
is best likened to a particularly pendant and flaccid human breast (see fig. 6).
Cephalad and caudad, the prominence of the breast thins out as skin folds —
merging with the general body skin above and below the breast; upon the
anterior fold of the right breast there is a minute skin papilla which I

= ei kl —

ee SS ae
*e™ a ” site a =

i Ot pe ie a ee ha
~ P .

The Genitalia of Galeopithecus 199

__presume to be a rudimentary and functionless nipple—this rudiment is want-

ing on the left side, where only one nipple is present. The functional
nipples are large, the one upon the right side being considerably elongated ;
this is almost certainly the result of recent suckling, and it is obvious that
the young exerts a considerable traction upon the nipple. I should think
that it is extremely probable that the nipple is used as an “anchoring
nipple” by the premature young in the same way as the marsupial teat is

———

ys,

6 OMAR SE ORS

1 VRAIN
NAN

} it TR

Ky ( *
AY

Fic, 6.—Left mammary gland of adult female ; this gland having only one nipple.

used. The likeness to the marsupial teat is striking; and in this connexion
it is interesting to recall the functionally similar anchoring nipples of some
of the Rhinolophid bats.

In the specimen that I have examined there are therefore two mammary
glands each provided with one functional nipple, and upon one side only
a functionless rudiment of another nipple placed immediately in front of
the fully developed one.

PosstsLE TRACES OF A Broop AREA IN GALEOPITHECUS.

Concerning the appearance of a pouch rudiment and ridges which I have
figured upon the abdominal wall of the young female specimen there is a

200 Professor Frederic Wood Jones

great deal of uncertainty. In my young specimen it was conspicuous, and
the figure depicts its outstanding features; in the adult I find no trace of
it (fig. 2). The resemblance to a marsupium rudiment was at once obvious,
and I had figured it before I had studied the work of Professor Parker.
In his Hunterian Lectures of 1884 on Mammalian Descent, Parker first drew
attention to the condition. His reference to it is not very precise, and
practically no details can be gathered from the figure which he gave of it,
but it is quite certain that he regarded it as a marsupial feature. Gervais
has figured a young female in about the same stage of growth as the
example demonstrated by Parker, and, although the figure is an excellent
one, no trace of this formation appears. Leche was unable to discern it on
an embryo supplied him by Dr Jentink, and almost all zoological works
ignore its possible existence. Leche and others have gone further than
this, for it is declared that even were such a structure as is described and
figured by Parker to be present it could certainly claim no kinship with any
basis of the marsupium. Leche dismisses it altogether from discussion as
such a rudiment, for the reason that the nipples are not situated within it.

I am not certain that these sweeping assertions carry the weight that at
first sight would seem to belong to them. The presence of this shallow
pouch appears to be variable in the young, it certainly does not contain the
nipples, and apparently it disappears in the adult, yet I think that none of
these facts necessitates our putting it aside without further consideration.
Very similar features in other Eutherian Mammals have before now been
brought forward with claims to be considered as next-of-kin to the mar-
supium, and in the dismissal of their suit I think that the impression that
they claimed to be rudiments of a highly specialised Diprotodont marsupium
has influenced the judgment. To picture a structure as being a persistent
remnant of an elaborated embryo-carrying marsupium of a Diprotodont is a
thing very different from imagining it to represent that anatomical basis
which, already present in the Prototheria, may or may not become more
highly specialised in the Polyprotodonts, finally culminating in the extra-
ordinary “marsupial pouch ” of the Diprotodonts. As representing such an
anatomical basis I am inclined to regard the shallow pouch to which Parker
called attention, and the condition of which in my specimen I have illus-
trated. Among my reasons for so regarding it are that I do not think the
anatomical basis which culminates in the development of a pouch in some
few animals is always rightly understood; that very much more striking
imitations of the pouch, and other “marsupial” features, are present in
some, even adult, Insectivora; and that attention has already been called
by many zoologists to dental resemblances between Galeopithecus and
Perameles.

The Genitalia of Galeopithecus 201

a Tue Petvic Sympuysis.

Without exception, I believe, zoological works which mention the con-
dition of the symphysis describe it as being “long.” Flower (11) says it
“is long, as in the Carnivora, and becomes ankylosed.” When the mere
statement is made that the symphysis is long, it is difficult to know what

type of symphysis is taken as a standard with which the comparison is
-made; but when the pelvis of Carnivora is instanced (although the
instance covers a great variety of types) it is only possible to say that
in comparison the symphysis of Galeopithecus is short. Of the whole

Fic. 7.—Embryo and placenta ; from Harrison Allen, after Gervais.

ischio-pubic ramus, from the spine of the pubis to the tuber ischii, the
symphysial area is less than one-fourth in Galeopithecus, and is therefore
somewhat shorter than the corresponding area in man, and less than a
half of the same area in the dog. It is certainly longer than the sym-
physis found in most bats, for in them the symphysial area tends to
diminish until, in most families, it is lacking altogether ; but compared with
the primitive type of mammalian pelvic girdle, that of Galeopithecus is
distinguished by the shortness of its symphysial area. This point is not
without its importance, and will be dealt with fully elsewhere.

202 Professor Frederic Wood Jones

DEVELOPMENT AND PLACENTATION.

I do not know of any published work upon the details of embryological
development of Galeopithecus. Gervais has figured an embryo which was
received from Diard, who collected it in Java in 1845. This figure is
reproduced by Harrison Allen (12), and from his reproduction I have
drawn fig.7. The placentation as it is shown in this figure agrees with
that of the Chiroptera and Insectivora, and differs, of course, from that
typical of the lemurs.

SUMMARY AND CONCLUSIONS, —

Even without an examination of the actual foetal stages it is quite
possible to determine with, I believe, certainty the route which the
external genitalia of Galeopithecus have followed in their development.
It seems obvious that they have undergone that cloacal outfolding which
is seen in all the Primates and in the Chiroptera, as well as in some of
the Insectivora. With all these groups, as Leche and others have shown,
Galeopithecus shows affinities in other systems and organs. But the
study of the genitalia affords this amount of precision, that though
individual features may be seen paralleled in representatives of the
Primates or of the Insectivora, the whole picture is seen only in the
members of one order—the Chiroptera. The whole adult picture of the
genitalia of Galeopithecus is seen with remarkable faithfulness in the
embryos of bats; and even in some adult bats the likeness is very
striking. Taphozus perforatus, for instance, agrees with Galeopithecus
in uterine form as well as in the characters of the external genitalia and
the presence of a circumanal pouch, which is here very much better
developed in the male. In the whole of the genitalia Galeopithecus
shows no feature which is not seen again in members of the Chiroptera,
and in the embryos of this order an identical combination of all the
peculiar features is common.

Judging from this one system alone, one might therefore conclude that
the affinities of Galeopithecus were most strongly with the bats, and that
the adult of Galeopithecus resembled most closely the embryonic stages
of that order. I do not think that this finding is at all out of harmony
with the evidence derived from all the other systems and organs; and
although other systems are outside the scope of this paper, I would point
out the similarity of the adult condition of the patagium of Galeopithecus
to the embryonic condition of that of the bats. Such a conclusion is of
course by no means new. According to Parker (op. cit.), “it might be
said of Nature that she tried her ’prentice hand on the Colugo, and then

Se ee

Wo ee

ea SO

eS ee eee

The Genitalia of Galeopithecus 203

afterwards she made the bats”; and he summed up the position by saying
“ We have in this beast a scarcely modified Early Tertiary bat.”

Chapman, although he follows Leche in likening the genitalia to those
of the lemurs, concludes that “there can be but little doubt that the
Chiroptera are the descendants of Galeopithecus, or more probably that
both are the descendants of a Galeopithecus-like ancestor.”

If it be accepted that, even on broad lines, embryonic conditions are
akin to ancestral stages, then, from a study of the genitalia of Galeopithecus,

these quoted opinions can be well supported, for it is only possible to

conclude that Galeopithecus represents an ancestral form from which the
Chiroptera have sprung.

REFERENCES.

(1) Warernousg, G. R., “On the Genus Galeopithecus,” Trans. Zool. Soc., 1838,
Bd. ii., 1841, p. 335. This paper deals with the specific characters of skulls.

(2) Gray, J. E., Catalogue of Monkeys, Lemurs, and Fruit-eating Bats in the
Collection of the British Museum, 1870, p. 97. Deals with specific characters and
nomenclature.

3) Dennys, N. B., A Dictionary of British Malaya, 1894, p. 136.

4) Hosx, C., A Descriptive Account of the Mammals of Borneo, 1893, p. 37.

5) WALLACE, A. R., The Malay Archipelago, p. 104.

6} CaNnTOR, TaEovoRE, M.D., “ Catalogue of Mammalia inhabiting the Malayan
Peninsula and Islands,” Jour. Asiatic Soc., Bengal, vol. xv., 1846, p. 178.

(7) Lecue, WitHeio, “ Uber Siiugethiergattung Galeopithecus. Ein Morpholo-
gische Untersuchung,” Eongl. Svenska Vetenskaps-Akademiens Hardlingar, Bd. xxi.,
No. 11, Stockholm, 1886.

(8) Cuapman, Henry C., Proc. Acad. Nat. Sci. Philadelphia, April 1902,
pp. 241-254, and plate xi. A good .réswmé in English of all points of affinity of
Galeopithecus ; largely founded on the work of Leche.

(9) Gervais, “Mémoire sur les formes cérébrales propres a différents groups
de Mammiféres,” Jowr. de Zool., t. i., 1872, p. 425.

(10) Rosy, H. A., “ Recherches anatomiques sur les Mammiféres de Vordre des
Chiroptéres,” Ann. Se. Nat. Zool., 1881 ; see especially pp. 111-175.

(11) Frower, W. H., An Introduction to the Osteology of the Mammalia, 3rd ed.,
1885, p. 320.

(12) AuLEeN, Harrison, “On the Embryos of Bats,” Contributions from the
Zoological Laboratory of the University of Pennsylvania, vol. i. No. 2, 1895, pp. 29, 30.

OBSERVATIONS ON THE POPLITEAL GROOVE ON THE FEMUR.
By GiLBert I. StracHan, M.D., Demonstrator of Anatomy, Uni-
versity of Glasgow.

THE popliteal groove which is so prominent a feature in almost all femora
has always seemed to be more explained away than actually accounted for.
It is constant in occurrence, direction, and position, and the causative factors
must therefore be correspondingly constant.

The fact that the tendon of m. popliteus is inserted into it far forward
—though not at its most anterior part,—and also
that the tendon lies in the posterior part of the
groove in acute genuflexion, has led to the present
description that the groove is caused by the
presence and pressure of the tendon in that
position of genuflexion.

The main objections to such a view are first
of all that the groove extends anteriorly quite
half an inch beyond the insertion of the popliteus
tendon (fig. 1). The groove thus carried forwards
is directly continuous with the posterior part, and,
so far as I know, this anterior prolongation has
not previously been differentiated. It is clear
that the tendon can have no share in producing
at least this anterior part, to which, indeed, it
Fic.1.—To represent the anterior bears no relation. Again, if the tendon causes

part of the popliteal groove. the groove, the groove would be at least as wide

X, point of insertion of tendon of m. z ; y f :
popliteus; A, part of the groove posteriorly as at the point of tendon insertion ;

Of the groove posterior to that indeed, the tendency would be for it to be wider
point. ‘ °
posteriorly, as the tendon begins to expand when
traced medialwards to become the muscle. But on examination we find
that the groove becomes rapidly narrower when traced posteriorly, and
finally ceases at the upper part of the posterior rim of the condyle (fig. 2).
Now, the pull of a tendon is usually in a straight line, and we would
expect, if an osseous groove is formed, that it would produce a straight
gutter for itself. But the popliteal groove is a curve which in the erect

position extends from below and in front of the most prominent part

Observations on the Popliteal Groove on the Femur. 205

of the external condyle upwards and backwards parallel to the articular
edge. It is difficult to see how a tendon acting in a straight line can
produce a curved imprint on bone.

Lastly, if a tendon is going to produce an osseous groove for itself it
will do so, other things being equal, in a position where it is constantly
lying and in a direction in which it is constantly acting, as does the biceps
tendon on the humerus. But the tendon of m. popliteus lies in the groove
of that name only in acute genuflexion—an attitude only momentarily
assumed ; whereas in the usual position—the erect position—only a faint
bevelling is produced by the tendon, and that on the anterior part of the
inferior lip of the groove (M‘Kay).

G.- 1.5.

Fic. 2.-—-To represent the width of the popliteal groove in various situations.
A, at the insertion of m. popliteus ; B, posterior to A ; C, still more posterior to A.
Three tracings from a sectioned specimen,

These considerations, though important in showing what does not cause
the groove, bring us really no nearer to what does cause it. In considering
this problem certain important morphological considerations arise.

The popliteus muscle in man and in most other mammals is attached to
tibia and femur; but in marsupials, as in reptiles, it stretches between the
tibia and the head of the fibula, and is a rotator fibule. In the lemur an
intermediate stage is seen (Gordon Taylor and Bonney), the tendon being
inserted on the external femoral condyle, while a sesamoid bone re-
presenting its fibular attachment (the true head of the fibula ?) is developed
in the tendon.

Now, the external (fibular) lateral ligament derived morphologically
from the m. peroneus longus (Sutton) exerts a strong bracing pull on its
attachments, especially in extension—the most common attitude. This pull
will act all the more powerfully on the femur as that bone inclines down-
wards and medially and forms a distinct angle with the vertical fibula.

206 Observations on the Popliteal Groove on the Femur.

When a tendinous or ligamentous insertion exerts traction on its osseous
attachment it is a rule (Wolff’s law) that a bony elevation arises at that
point as though the bone were being drawn out locally. Now, putting
these considerations regarding m. popliteus and the external lateral ligament
together, our hypothesis is that the sesamoid bone described in the lemur
has in man and the higher mammals travelled up and as it were fused itself
on to the femur; it is then pulled out into a sharp edge by the localised
action of the external lateral ligament, as described. This explains the
development of the anterior part of the upper lip of the groove and also of
the anterior part of the external epicondyle of the femur.

The posterior part of the external epicondyle of the femur bears the
imprint of origin of the lateral head m. gastrocnemius. This muscle pulls
in an inward and downward direction, and, its origin being more diffuse
than the insertion of the external lateral ligament, its traction elevation
will be of greater extent, but not so well defined as the other.

It will be noted that the upper lip of the popliteal groove formed by
these traction forces is almost horizontal and is absolutely so on slight
flexion of the hip.

With regard to the lower lip of the groove, all that is to be seen is the
everted flange of the condylar articular margin, smoothed out at one part
where the tendon of m. popliteus passes over it. An anterior groove for
the external lateral ligament so often described is not present in any
specimen ; indeed, in every movement of the joint the ligament and tendon
cross the lower lip of the groove at one and the same spot, the ligament of
course being superficial to the other. Supporting this theory of causation
of the lower lip of the groove I have found in the full-time foetus the lower
lip blunt and rounded, not yet having been subjected to weight pressure ;
also, the part of the groove previously described as lying anterior to the
insertion of the popliteus tendon has not yet developed for lack of the
ligamentous pull, owing to the foetal position. In a subject ztat. six years
this anterior part was becoming quite well defined, as was the entire inferior
lip, the adult conditions now coming into play.

The floor of the groove is thus, according to these views, normal femoral
surface, the lower edge a pressure ridge, and the upper lip a traction ridge.
This explains why the inferior lip of the groove is parallel to the articular
margin.

This hypothesis I believe will stand investigation, as it explains the
conditions present, which the usual description quite fails to do.

207

JOURNAL OF ANATOMY AND
PHYSIOLOGY

THE STRUCTURE OF THE BLASTODERM, AND THE CON-
TINUITY OF THE CELL-ELEMENTS DURING THE EARLY
STAGES OF DEVELOPMENT. By J. Cameron, M.D., DSce., .
Professor of Anatomy, Dalhousie University, Halifax, Nova Scotia ;
and R. J. Guapstone, M.D., F.R.C.S., Senior Demonstrator and
Lecturer on Anatomy, King’s College, University of London.

1. INTRODUCTORY.

THE conception of a general continuity of the protoplasmic elements which
form the tissues of all living organisms is by no means new. It preceded
the “cell theory,” and although “cells” have for many years been regarded
as “independent units, each having its separate life-history,” there has
always existed a considerable number of observers who, while not question-
ing the theory of separate cells, have described organic continuity of the
cell-elements in the particular organ or tissue which they have specially
studied. Thus Sedgwick (28) in Peripatus and in chick embryos, Graham
Kerr (17) in tracing the continuity of developing nerves with muscle in
Lepidosiren, Bernard in his researches on the structure of the retina,
Studincka (30) and F. E. Schultze (26) in studying the structure of epithelial
cells, have ail been led to the same conclusion, namely, that there is a
general continuity of the cell-elements in these tissues. Some of these
writers, notably Sedgwick and Bernard, have extended the conception of
continuity of the cell-elements in the tissues which they specially examined
to continuity of the cell-elements in general.

Wilson (33) has pointed out and emphasised the very important fact
that in Amphioxus and Echinoderms “the results of experiments on the
early stages of cleavage are difficult to explain save under the assumption
that there must be a structural continuity from cell to cell.” This con-

clusion is supported by the work of Hammar (10) on the ova of Echinus.
VOL. L. (THIRD SER. VOL. XI.)—APRIL 1916. 14

208 Professor J. Cameron and Dr R. J. Gladstone

More recently, Hardesty (11) in the nervous system, Godlewski (9)
and M‘Gill (20) in muscle tissue, His (14) in epithelia, and Spalteholz (29)
in the connective tissues, have demonstrated the continuity of the cell-
elements in these different forms of tissues. Notwithstanding the evidence
brought forward by these and by many other observers, the theory that
all living tissues are built up of independent units called “cells” is still
almost universally held, and that the “cell” is in Briicke’s words “an
elementary organism ” (3).

In tracing the history of the cell-theory which was promulgated by
Schleiden (25) and Schwann (27) in 1838 and 1839, we find that Heitz-
mann (13), so long ago as 1873, contended that cell-division is incomplete
in nearly all forms of tissue, and that even when cell walls are formed,
they are traversed by strands of protoplasm, by means of which the cell
bodies remain in organic continuity. The whole body was thus conceived
by him asa syncytiwm, the cells being no more than nodal points in a
general reticulum, the tissues thus forming a continuous protoplasmic mass.

It has been conclusively demonstrated that in nearly all plant tissues
the cell walls are traversed by delicate intercellular protoplasmic bridges,
whilst in the case of animal tissues many observers have described the
existence of similar bridges, one of the most familiar examples being the
so-called “ prickle cells” of the stratum Malpighi of the skin. These will
be described later in detail when we come to deal with the structural
features of epithelial tissues. A more important example is furnished by
the protoplasmic connexions of the cell-elements of the corona radiata, not
only with each other but actually with the ovum itself. This structural con-
tinuity, which has been already demonstrated by Flemming (8), Heape (12),
and Retzius (23), is illustrated in fig. 1, which shows two stages in the
evolution of the ovarian ovum of the cat. In the early stages (A) it will
be noticed that the odplasm is directly continuous with the cytoplasm of
the surrounding cell-elements. This appearance is made more manifest
by the fact that the ovum possesses no zona pellucida at this stage, though
the continuity is still distinct even in the later stages (B). This observa-
tion is of the utmost importance in relation to the question of the in-
heritance of acquired characters, for it is not in agreement with the theory
of the immutability of the germ plasm, postulated by Weismann (32), and
upon which his theory with regard to the non-transmissibility of acquired
characters has been largely founded. It seems to us that the organic con-
tinuity we have described between the germ plasm and the cytoplasm of
the “somatic cells” must surely mean that the former is liable to be
influenced by the latter, apart from the nutritive function, which is
generally admitted. We hope to prove in a subsequent paper that the

Structure of the Blastoderm 209

Fic. 1.—Two stages illustrating the development of the ovarian ovum and Graafian
follicle in the cat. A shows an early stage, before the complete development of the
zona pellucida. It will be observed that the cytoplasm of the follicle cells is con-
tinuous, not only with that of the ovum, but also with that of the adjacent cells of
the same layer, and of the ovarian stroma. B, later stage, in which it will be noted
that the zona pellucida now forms a distinct boundary zone, but does not completely
separate the ovum from the cells of the corona radiata. Processes from these cells
pass through the zona pellucida, and are continuous with the cyto-reticulum of the
odplasm.

210 Professor J. Cameron and Dr R. J. Gladstone

“germ cells” have a similar relation to the surrounding “somatic cells” in
the male also.

It will be our aim in this memoir (to which the present paper is merely
an introduction) to demonstrate that—

(1) It is the nuclei with their contained chromatic material which
should be regarded as units, rather than the cell-elements.

(2) There is an organic continuity between the cell-elements of the
connective tissues, the cell-elements of the central and peripheral nervous
systems, and in certain epithelial layers.

(3) This continuity is in most cases primary, and not secondary.

(4) The so-called intercellular substance! forms an essential part of
this continuous living tissue, which with its contained nuclei forms a
plasmodiwm.

The connexion of cell-elements together by means of delicate filaments
continuous with the cyto-reticulum and nuclear network of the individual
cells was demonstrated in the retina by the late Mr H. M. Bernard (2).
This author afterwards extended his observations to other tissues, and
described a continuous network of linin threads, uniting and passing
through the cell-elements. This he termed a protomitomic system.
Further, he considered nuclei to be aggregations of chromatin at the
intersections of the linin network.

Our views in the main accord with those of Bernard. Our observations,
however, indicate that the mode of continuity between neighbouring cell-
elements is not necessarily through the linin network alone, but also by
a direct continuity of the cytoplasm, which has existed from the very first.

2. THE Earty Ovum.

It is well recognised that in the early stages of segmentation of
amphibian and avian ova the division is incomplete. For example, the
divisional planes in the segmenting cicatricula of the bird’s ovum do not
involve anything like the whole thickness of the cicatricula ; and what is
more significant still, it may be noted that these planes do not extend
peripherally into the periblast, as is well shown in the excellent micro-
photographs by Miss Blount in Lillie’s book on the development of the
chick (18). Fig. 2 is a drawing of a small portion of the ectoderm near
the yolk wall, from a transverse section through a chick embryo, incubated
eighteen hours. The section passes through the primitive plate, a short
distance behind the primitive groove, and shows, above, the ectoderm. —

1 We do not regard as living material, calcareous matter deposited in the matrix of
bone, or other inert substances deposited in the ectoplasm.

Structure of the Blastoderm 211

“Pris consists of fairly well defined cell-elements, which are mapped off
__ by thin partitions of darkly stained protoplasm, directly continuous with
the cyto-reticulum of the adjoining cell-elements, and also with the
_ protoplasm filling in the angular spaces between these. There are no

Fic. 2 is a drawing of a small portion of the ectoderm and entoderm, near the yolk wall,
from a transverse section through an eighteenth-hour chick embryo. The section
passes through the primitive a short distance behind the primitive groove, The

ectoderm is shown above. consists of well-defined cell-elements separated by
thin partitions of darkly stained protoplasm, which is directly continuous with the
eyto-reticulum of adjoining ‘‘cells,” and also with the gm orgem filling in the
angular spaces between the cell-elements. There are no clefts in these partitions, nor
can the partitions be regarded as cement substance ; for, as is clearly shown in the
large underlying entodermal cell-elements, they are continuous with and have the
same structure as the strands of the cyto-reticulum or spongioplasm. The faintly
stained entodermal cell-elements have a remarkable appearance in contrast with the
more deeply stained ectodermal layer. They appear to be distended with a clear
achromatic cytoplasm, almost identical in its physical characters with the nucleo-
plasm. Aftera careful study of this material we are convinced that it is a protoplasm
extruded from the nuclei in a nascent condition, in virtue of which it is achromatic in
its reaction to staining agents. Drawn under an } apochromatic objective with com-

pensating ocular x 7.

_ clefts in these partitions separating adjacent “cells,” nor can the partitions
be regarded as cement substance, for, as is clearly shown in the large
underlying entodermal cell-elements, they are continuous with and have
the same structure as the strands of the cyto-reticulum or spongioplasm.,

212 Professor J. Cameron and Dr R. J. Gladstone

The faintly stained entodermal cell-elements in fig. 2 have a remarkable
appearance, which contrasts with the more deeply stained ectodermal layer.
They appear to be distended with a clear achromatic cytoplasm, almost
identical in appearance with the nucleoplasm. After a careful study of
this material, we are convinced that it is a protoplasm extruded from the
nuclei in a nascent condition, in virtue of which it is achromatic in its
reaction to staining reagents. This nascent non-staining cytoplasm can
be demonstrated also in the entypy stage of the mouse embryo (fig. 10),
where it exhibits itself in the form of clear achromatic zones immediately
surrounding the nuclei or as clear refractile globules in the general
protoplasm. This appearance is likewise characteristically shown in the

Fic, 3.—Segmenting ovum of Echinus esculentus, sixteen-cell
stage, showing blastomeres surrounded by a continuous
‘*eetoplasmic layer,” which forms a connecting medium be-
tween the cells, and, in conjunction with these, constitutes
a ‘‘ complete organism,” or ‘‘individual,” as distinguished
from a ‘‘cell-colony,” united by an extraneous ‘‘ cement
substance,”

deeper layers of the trophoblast of the chorionic villi (fig. 14). One of
us has previously demonstrated the extrusion of this nascent achromatic
cytoplasm from the nuclei of the developing retina (4 and 5) and brain (6).

The continuity of the cell-elements of the morula mass may also be
observed in invertebrate ova. For example, fig. 3 is a drawing which one
of us executed whilst studying the fertilisation and segmentation of the
ova of Echinus esculentus at the Millport Marine Biological Laboratory
in 1903. In the morula stage of development of this species it can be
clearly recognised that the blastomeres are held together by a thin layer
of homogeneous protoplasm which exhibits itself as a very delicate
achromatic zone surrounding the periphery of the morula mass. Hammar
(10) has, moreover, shown that in another species of Echinus (Z. miliaris)

‘
Teg
.

“

Structure of the Blastoderm 213

_

the segmenting ova possess what he terms an ectoplasmic layer which not
only surrounds the blastomeres, but can also be traced deeply between
these elements. He was able to demonstrate this “ectoplasm” in ova
from the two-cell stage up to that of the blastula, and he regards it as
establishing a structural continuity between the cell-elements, and forming
an essential part of the organism. The achromatic perimorular zone
shown in fig. 3 thus clearly corresponds to the ectoplasm described by
Hammar in Echinus miliaris, and we consider it to be a vital constituent
of the organism, and by no means the inert substance it is generally

Fic. 4,—Frog’s ovum, showing an early stage in segmentation. The
segmentation is incomplete, and the cell-elements at the ‘‘ animal
pole” are seen to be continuous with the deutoplasm of the ‘‘ vege-
tative pole,” in which the lines of cleavage are only just visible.

considered to be. It probably forms the medium through which one
blastomere influences another during development.

It is a well-known fact that in centrolecithal ova, segmentation is incom-
plete, and it has been shown by Morin (22) that the daughter nuclei which
at first lie in the middle of the ovum, subsequently migrate freely towards
the surface along the radiating strands of the protoplasmic reticulum.

This direct structural continuity of the cell-elements of the morula mass
appears to have been recognised by Wilson (33), who in his standard book
on The Cell makes the following significant statement: “The unity of the

‘embryo is not caused by a mere juxtaposition of the cells . . . this unity

is physiological, and the facts point towards the conclusion that there must
be a structural continuity from cell to cell, which is the medium of co-
ordination.” It follows that if this structural continuity be broken or

214 Professor J. Cameron and Dr R. J. Gladstone

interrupted by mechanical displacement of the blastomeres, the unity of
the organism is likewise broken up.

One of the most convincing proofs of the direct structural continuity
of the blastomeres is shown by the following experiments. Roux (24),
in an extensive series of articles covering the period between 1883 and
1908, elaborated a theory of development known as the germinal localisation
theory of self-differentiation. According to this, certain portions of the
ovum are early set apart for the formation of a definite organ or tissue
of the embryo. The result of this idea is that by the time the morula
stage is reached certain groups of cells are set aside for this purpose. It
is evident, then, that according to this theory each of the two primary
blastomeres ought to produce a hemi-embryo, and Roux at first considered
that he had succeeded in producing from the blastomeres of frog’s ova
such a hemi-embryo, passing through the stages of hemi-morula, hemi-
blastula, and hemi-gastrula.

Subsequent experiments by Wilson (33) and Morgan (21) on Amphioxus,
and Jenkinson (16) on the frog, gave results diametrically opposed to those
of Roux. They found that if the two primary blastomeres were completely
separated from one another, each produced a complete embryo, though only
half the size of the normal. Even a quarter blastomere was found to give
rise to a normal blastula, gastrula, and sometimes even to the stage of an
embryo, but only one-quarter the normal size. An eighth blastomere
produced a morula, but this did not gastrulate. Finally, a one-sixteenth
blastomere produced merely an irregular clump of cells. Further ex-
periments by Driesch (7), Jenkinson (16), and others on the ova of
Echinus gave almost identical results.

The conclusion one arrives at as a result of these foregoing experiments
is, that if the two primary blastomeres did normally separate from one
another completely, each ought always to give rise to a complete embryo
in the natural process of development, but of course this is not so. The
only inference, then, is that the continuity of the protoplasm of the two
primary blastomeres is not completely severed, and this permits some
mutual influence or interaction between the two, the result: being a single
complete embryo.

On studying later stages in the segmentation of the amphibian ovum,
we discovered that the cyto-reticulum of the blastomeres could be traced
through the cleavage planes as a direct connexion between the cell-
elements. This appearance is rendered more striking by the fact that -
these strands cross the above-mentioned planes at right angles (fig. 5).
We thus found a direct continuity in the morula stage which presumably
must have resulted from a division of nuclei in a mass of protoplasm—

Structure of the Blastoderm 215

the whole constituting a plasmodiwm. The latter term is the only one
which appears to us to meet the case, and we will therefore continue to
employ it throughout this paper. It is certainly a more accurate title than
syncytium, a term which suggests that the cell-elements were at one time
separate and had become fused together secondarily. We hold, that proto-
plasmic continuity must have existed from the very first.

Fic. 5.—Later stage in the segmentation of a frog’s ovum. The divisional planes between
the cell-elements are now distinctly visible, and in the section appear as a proto-
plasmic network surrounding the cells, and characterised by a rich deposit of pigment
granules, The cyto-reticulum of the enclosed cells is also pigmented, and its filaments
will be seen to be continuous, not only with the pigmented planes of intercellular
protoplasm, but also with the cyto-reticulum of neighbouring cell-elements.

The protoplasm of the blastodermie plasmodium can be conveniently
divided into two kinds. That immediately surrounding the nuclei con-
stitutes the endoplasm, and is of course readily recognisable. It is not so
easy, however, to recognise the second kind, which we have decided (by
contrast) to term the ectoplasm. The latter will be found not only to
intervene between the cell-elements, but also to form a continuous zone
surrounding the whole blastula mass. If this ectoplasmic layer increase in
amount, the cell-elements become more or less completely separated ; but

216 Professor J. Cameron and Dr R. J. Gladstone

even then it still forms a connecting medium, At this point we wish to
emphasise the importance of recognising this differentiation of the proto-
plasm of the blastula mass into a clear homogeneous ectoplasm and a
perinuclear endoplasm ; for we hope to be able to demonstrate subsequently
a similar process of differentiation during the stages of development of
practically all the tissues of the body, which will be found to constitute an

Fic. 6 is a microphotograph of a section through the free blastula of a mouse, which is at
one part of its circumference becoming attached by fibrinous material to the uterine
mucosa. The cell-elements are incompletely separated from one another. Some of
the nuclei are undergoing karyokinesis and appear to be imbedded in a continuous
protoplasmic matrix. The wall of the blastula must therefore be regarded as a “‘ plas-
modium,” since the dividing nuclei are contained in a continuous matrix, and are not
situated in separate ‘‘cells.” From a specimen kindly lent by Professor Dendy. The
section was stained with ‘‘ picro-indigo-carmine.”

important phase in their life-history. Thus, if one studies tissue-ontogeny
from this new standpoint, one will be provided with remarkable evidences
of the persistence of this primitive plasmodial condition even in the adult,
the result of which, we venture to hope, will be a much more simplified
conception of the histological structure of the body, than that provided
by the cell theory, as usually understood.

In the blastula stage of mammals the separation of the cell-elements
is also incomplete, and divisional lines are often absent altogether, Thus

Structure of the Blastoderm 217

—

fig. 6, which represents a critical stage in the development of the blastoderm
of the mouse, simply shows a nucleated layer of protoplasm enclosing the

Wee iia a ee a

ee he Ses

Fic. 7 is a higher-power view of the blastula shown in the previous figure in order to
demonstrate its structure more clearly. Drawn under an 4 apochromatic objective
with compensating ocular x 7.

cavity of the blastocyst, and constituting its wall. It will be observed that
the outlines of the individual cell-elements, if visible at all, are only very

218 Professor J. Cameron and Dr R. J. Gladstone

imperfectly shown, so that there is an obvious continuity of the protoplasm.
The chromatin of some of the nuclei is in a disturbed condition (fig. 6),
indicating that they are in one of the stages of karyokinesis. After studying
this microphotograph one fails to recognise any resemblance to the conven-
tional diagrams of the blastodermie vesicle which have been handed on from
text-book to text-book. To represent cells sharply marked off from one

Uterine
wall.

Fic. 8 is a low-power view of the entypy stage of 2 mouse embryo, which will be
recognised in the centre of the microphotograph,

another by strongly marked boundary lines, is to give to students of em-
bryology an inaccurate impression of the structure of the blastoderm, and it
is to be hoped that this conventionality will soon be finally disposed of.
This continuity is- well maintained in the entypy stage of the mouse
embryo, as shown in figs. 8,9, and 10. We have represented in fig. 10
a very highly magnified view of a group of the cell-elements shown in
fig. 9. At first sight these appear to be mapped off from each other by
divisional planes in the most definite manner. A more intimate examination
clearly shows, however, that this appearance is due to the differentiation

Structure of the Blastoderm 219

of the protoplasm of the plasmodium into ectoplasm and nascent endoplasm.
The latter forms the very definite zone immediately surrounding the
nuclei, whilst the ectoplasm which at first sight appears to constitute the
“partitions” between the individual cell-elements forms one continuous
-bond of union for the whole mass.

Take another example from a higher type of mammal. The plasmodial
structure of the blastoderm has been very clearly represented by

Fic, 9 is a high-power view of the entypy stage shown in fig. 8.

Hubrecht (15) in his well-known figure of the blastocyst of Tarsius spectrum
(fig. 11). In this both the “formative cell mass” and the trophoblast
appear to be a plasmodium. The fluid contained within the blastocyst
seems to be a secretion from its plasmodial wall. The wall itself is
represented as being mainly composed of a mass of protoplasm containing
nuclei one of which is shown in the act of dividing. Here and there in
the figure are cell-elements which have become mapped off in a greater or
lesser degree from the general plasmodium.

220 Professor J. Cameron and Dr R. J. Gladstone

In the blastocyst of the bat, as figured by van Beneden (1), the con-
tained fluid appears first in the form of small vacuoles within the plas-
modial mass, As these increase in size they coalesce to form the fluid
filling the central cavity.

Fic. 10.—Portion of the endoderm and underlying ectoderm from the preceding
specimen. The nuclei, some of which are undergoing mitosis, are seen to con-
tain a clear nucleo-plasm, In the surrounding protoplasm is a similar clear
material which appears to have been extruded in — from the nuclei,
and sometimes forms a clear zone surrounding the nuclear membrane. This
clear protoplasm we speak of as ‘‘endoplasm,” and we believe it to be
recently formed, ¢.¢. in a nascent condition. The surrounding granular
protoplasm is stained, and forms a continuous matrix. This granular proto-
plasm corresponds to the ‘‘ectoplasm,” and it will be noted that where it forms
a partition between adjacent nuclei, there is no indication of this partition
consisting of two cell membranes lying in contact with one another, nor is
there any indication of a space separating adjacent cell-elements. Drawn
under an 4 apochromatic objective with compensating ocular x7.

The relation of the two central cavities to the mesenchyme in the ~
Teacher-Bryce (31) ovum also suggests that in the human subject the
cavities of the blastocyst are formed within a plasmodium much inthe
same way as in lower mammals.

Structure of the Blastoderm 221

“~
a

3. CONTINUITY OF THE ECTODERM, MESODERM, AND ENDODERM.

A study of the three-layered condition of the embryo shows that there
still exists at this stage a direct continuity of the cell-elements. Those
of the mesoderm usually exhibit a multipolar character, and it has been
taught that this is due to an outward growth of processes from originally
rounded cells which unite with those of neighbouring cells to form a
network, or, in other words, a secondary continuity (fig. 12). A close
examination of this stage of embryonic development shows, however, that
these processes have been in direct continuity with one another from the
very outset, the connecting strands of protoplasm being drawn out as a

aoe, Te i a
we = Di <> My ys. es oleh! « ack Bt sky Vy > PY a
Go ary ee je Ty ee ee
2 . . *S ye ea oe

j F “ -

- Sate ee as

Fic. 11 is a drawing of Hubrecht’s well-known figure of the blasto-
cyst of Tarsius spectrum. In this, both the formative cell-
mass and the trophoblast appear to form a plasmodium.

result of the separation of the nuclei. Moreover, the processes of the
mesodermic cell-elements lying next the ectoderm and endoderm are
frequently seen to be in direct continuity with the protoplasm of these,
and all three layers are distinctly continuous with one another at the
primitive streak. Here also the cell-elements are imperfectly separated
from one another, so that the actively growing tissue in this region must
therefore be regarded as a plasmodium.

On tracing the ectoderm outward from the primitive streak the cell-
elements certainly do appear to be marked off from one another by definite
divisional planes. Upon closer examination, however, they are seen to
be connected and held together by a thin ectoplasmic layer on the surface.
This is most readily visible in the angles between the cell-elements, as
in-the entypy stage of the mouse embryo. It is probable that these
elements are also connected with one another laterally, for they hold

222

Professor J. Cameron and Dr R. J. Gladstone

Fic. 12.—Transverse section through the primitive groove, and three primary layers of a

chick embryo, incubated eighteen hours, The illustration shows one lip of the groove
on the left-hand side; the ectoderm (ect.) is above, the endoderm (end.) below ;
between these two layers is the mesoderm, which consists of irregular strands of proto-_
plasm connected by bridges of varying thickness, and containing nuclei, some of which
exhibit karyokinetic figures. The cell-elements of the mesoderm are not only con-
tinuous with one another, but are continuous also with the ectoderm and endoderm.
The continuity of the cell-elements of the mesoderm appears to be primary, for it will
be noted that those nuclei which show mitotic figures (see nucleus to left in illustra-
tion) are situated in thickenings of the general reticulum, and are usually connected
by protoplasmic bridges with several of the neighbouring nuclei. They do not appear
to us to conform to the usual description, namely, that isolated cells of a rounded
form wander out between the ectoderm and endoderm, and afterwards send out proto-
plasmic processes which join to form a reticulum, We seldom find isolated cells
undergoing karyokinesis, either at the growing edge of the mesoderm or in any part
of its extent between this and the primitive streak. Where such isolated cells are
present, we believe that the protoplasmic bridges which have connected them with
the neighbouring cell-elements from which they have originated have been broken —

in the Fs sala of the specimen, and the ‘‘cell” thus liberated has assumed a
rounded form,

Structure of the Blastoderm 223

——

closely together, and are not separated by the action of the reagents
employed for fixing the tissue, as they most certainly would be if the
cells were merely in a condition of contiguity instead of organic con-
tinuity. One can thus trace this ectoplasmic bond of union from the early

Wlha tape ag

Fig. 13.—Section through a villus from the chorionic vesicle of a 9-mm, human embryo.
The mesenchymatous core consists of a scanty meshwork of lightly stained proto-
plasm with nuclei at the nodes, and continuous externally with the granular
protoplasm of the surface layers. The mesenchyme of the villus is also in direct
continuity with the walls of the developing blood-vessels, one of which is shown cut
transversely, the other longitudinally. Drawn with a 4 objective.

developmental stages. Moreover, the intercellular material spoken of by
histologists as inert “cement,” and described by them as a secretion of
the cells, we interpret as ectoplasm, and thus as an integral part of the
living tissue.
The behaviour of the plasmodium during the three-layered stage ex-
emplifies an interesting tendency it is constantly displaying, namely, the
VOL. L. (THIRD SER. VOL. XI.)—APRIL 1916. 15

224 Professor J. Cameron and Dr R. J. Gladstone

surface cell-elements always arrange themselves in more or less definite
layers, thus giving rise to the so-called ectoderm and entoderm. Another
point which has impressed us strongly during these observations is, that
the mesoderm is not produced wholly by a proliferation of the cell-elements
in the region of the primitive streak, but also by a multiplication of the
nuclei throughout the general plasmodial mass; that is to say, a generalised

Fie, 14,—A portion of the surface layer of the villus shown in fig. 13 drawn under
an 4 apochromatic objective with compensating ocular x7. The drawing shows
an outer layer of oval, darkly stained nuclei, imbedded in a granular protoplasm.
Next to this outer plasmodial stratum is ‘‘ Langhans’ layer,” the nuclei of which
are approximately spherical and less deeply stained. They are surrounded by a
clear zone of unstained protoplasm similar in appearance to the clear nucleo-
plasm. This perinuclear protoplasm we speak of as nascent endoplasm, neigh-
bouring zones of which are separated from one another by septa of granular
stained protoplasm continuous externally with that of the outer layer, and
internally with the mesenchymatous core. These septa at first give one the
impression of separate cell-elements, but a closer examination shows that there
is direct structural continuity throughout the specimen.

instead of an entirely localised proliferation. Fig. 12 exhibits this general-
ised multiplication of the nuclei during the three-layered stage.

4. PLASMODIAL STRUCTURE OF A PLACENTAL VILLUS.

The central core of the villus (fig. 13) corresponds to the mesenchyme.
{t consists of a delicate protoplasmic network with nuclei at the nodes,
and thus exhibits the typical plasmodial structure. The surface of the
villus (shown highly magnified in fig. 14) exhibits the characteristic
tendency referred to in the previous section towards a layering of the

Structure of the Blastoderm 225

cell-elements. Thus it shows an inner single stratum—the “absorptive
layer of Langhans ”—whilst the outermost coating permanently maintains
its plasmodial character, constituting the “syncytium” of the chorionic
villus. The plasmodial structure of this tissue has never been questioned,
and has, in fact, been recognised for years. Still later, Langhans’ layer
merges with the syncytial coating of the villus, which then becomes spread
out to form a single stratum of nucleated cell-elements connected at certain
points with the protoplasm of the decidua basalis, and forming with it a

Fie. 15.—Section through the placenta of a 7-mm. guinea-pig embryo. The illus-
tration shows part of a trabecula between two of the cotyledons. It consists of
a plasmodial network, in the substauce of which large oval nuclei are imbedded.
Round each nucleus is a zone of lightly stained protoplasm, similar to the endo-
plasm surrounding the nuclei of Langhans’ layer in the chorionic villi. Drawn
under an { apochromatic objective with compensating ocular x 7.

continuum. The core of the villus consists of the typical mesenchymatous
network. In the trabecule of the meshwork are spaces which, as we hope
to describe later, develop into the blood-vessels of the villus. Fig. 13
shows two of these primitive blood- vessels, one cut transversely, the other
longitudinally. An examination of figs. 13 and 14 will show that the cell-
elements covering the surface of the villus are in direct continuity with
the mesenchymatous tissue of the core. The chorionic villus in all its
features thus affords an instructive study of the structural continuity of
developing tissue.

The maternal portion of the placenta likewise exhibits very strikingly

226 Professor J. Cameron and Dr R. J. Gladstone

its plasmodial character. The tissue of the decidua basalis becomes greatly
hypertrophied, and indeed reverts to its primitive plasmodial condition.
Fig. 15 shows this characteristic tissue in process of being transformed
into maternal blood sinuses.

5. SUMMARY AND CONCLUSIONS.

(1) In the developing blastoderm the nuclei with their contained
chromatic material ought to be regarded as the structural units rather
than the cell-elements as a whole.

(2) There is an organic continuity between the cell-elements of the
developing blastoderm both in vertebrates and invertebrates. In the
present paper we have traced this continuity up to the three-layered
stage in mammals and in the chick embryo, in the chorionic villi and
in the placenta. |

(3) This continuity is in most cases primary, and not secondary
(plasmodial rather than syncytial).

(4) Protoplasm may be differentiated into endoplasm and ectoplasm.
The nascent endoplasm forms a clear, highly refractile zone immediately
surrounding the nucleus. This merges into a more mature endoplasm,
which in its turn undergoes transition into a granular ectoplasm.

(5) The nascent endoplasm, the more mature endoplasm, and the
ectoplasm, represent three stages in the genesis of protoplasm. It is a
well-recognised fact that the protoplasm of every living tissue has a
limited period of activity during which its vitality is constantly being
revived and rejuvenated by regulated supplies of nascent material. The
latter is apparently a derivative of the nucleus, and is discharged from
this in the form of nascent endoplasm. It would appear, therefore, that
nutritive material ingested by the cytoplasm receives its final elaboration
in the nucleus. From this standpoint we would argue further that the
nascent endoplasm possesses the greatest activity, whilst the functions of
the ectoplasm are more of a passive nature and are mainly in the direction
of maintaining structural continuity between neighbouring cell-elements.

(6) The ectoplasm corresponds to the so-called intercellular substance,
and forms an essential part of the continuous living tissue which with
its contained nuclei constitutes a plasmodiwm.

ie gs

Structure of the Blastoderm 227

——_—_

REFERENCES TO LITERATURE.

(1) van Benzpen, E., “ Recherches sur les premiers stades du développement
Murin,” Anat. Anz., xvi., 1899.
_ (2) Bernarp, Henry M., Some Neglected Factors in Evolution, G. P. Putnam
l Sons, 1911. Also in Quart. Journ. Micros. Science, vols. xliii. to xlvii.
_ (3) Brécxg, C., “ Die Elementarorganismen,” Wiener Sitzber., xliv., 1861.
_ (4) Cameron, J., Journ. of Anat., 1905.
_ (5) Cameron, J., Jowrn. of Anat., 1912.
_ (6) Cameron, J., Brain, 1906.
7} Drrescu, H., Arch. Ent. Mech., x., 1900, and xvi., 1903.
(8) Fiemmine, W., Zellsubstanz, Kern, u. Zelltheilung, Leipzig, 1882.
(9) Goptewski, Archiv f. Mikro-Anat., Bd. 1x., 1902.
(10) Hammar, J. A., “Ueber eine allgemein vorkommende primaire Protoplasma
am ung zwischen den Blastomeren,” Arch. /. Mikro-Anat., Upsala, xlvii. p. 14,
(11) Harpesry, J., Amer. Journ. of Anat., vol. iii., 1904.
_ (12) Hearg, W., Quart. Journ. Micros. Sci., vol, xxiii., 1883.
_ _-—« (13) Herrzmann, J., Sitz. d. k. Akad. Wiss. Wien, xvii.
(14) His, Witueim, “Ueber Syncytien, Epithelien, u, Endothelien,” Verh. Ges.
d Natf. Leipzig, uxxm., ii. 2, 1901 (273-276). :
(15) Husrecut, A. A. W., Verhand. d. Koninklijke Akad. van Wetterschappen te
Amsterdam, viii., 1902.
(16) Jenxtyson, J. W., Hxperimental Embryology, 1909.
(17) Kerr, Granam, 7'rans. Roy. Soc, Edin., vol. xli., Part I.
18) Luniz, F. R., Development of the Chick, 1908, pp. 38-52.
(19) MBrinz, E. W., Texrt-book of Embryology, vol. i., 1914.
; oo M‘Git, Carouine, Internat. Monatsschrift. Anat. u. Physiol., Bd. xxiv.,

~*~ (21) Morean, T. H., Anat. Anz., x., 1895, and Arch. Ent. Mech., xix., 1905.
(22) Morin, Development of Astacus, Korschelt & Heider.

(23) Rerztus, G., “Die Intercellularbriicken des Eierstockeies, und der
_ Follikelzellen,” Verh. Anat. Ges., 1889.

_ (24) Roux, W., Virchow’s Archiv, 1889.
_ (25) Scuemen, M. J., “ Beitriige zur Phytogenesis,” Miiller’s Archiv, 1838.
(26) Scuurrze, F. E., Sitzwngsberichte der Kin. Pr. Akad. der Wissenschaften 2u
Berlin, 1896.
(27) Scuwany, Tu., Mikros. Untersuch. iiber die Uebereinstimmung in der
_ Struktur und dem Wachstum der Tiere und Pflanzen, Berlin, 1839.
(28) Sepewick, Apam, “On the Inadequacy of the Cellular Theory of Develop-
ment,” Quart. Journ. Micros. Sci., xxxvii.
(29) Spavrenoiz, W., Verhandl. Anat. Gesellsch., Rostock, 1906,
(30) Sruprnoka, F. K., Sitz. der k, bihm. Ges. der Wiss. in Prag, 1897.
_ — “Ueber Stachzellen und sternformige Zellen in Epithelien,” Sitz. der k.
_ bihm. Ges. der Wiss. in Prag, 1902.
(31) Tezacuer and Bryce, The Karly Development and Imbedding of the Human
Ovum, Glasgow, 1908,

(32) Weismann, A., The Germ Plasm, transl. by W. N. Parker, 1893.
_ (33) Wusoy, E. B, The Cell in Development and Inheritance, 1906, pp. 58-61,

TWO EXAMPLES OF CARDIAC MALFORMATION. By R. J.
GLADSTONE, M.D., F.R.C.S., Lecturer on Anatomy, King’s College,
University of London, and C. H. Reissmann, M.A., M.D., M.R.C.P.,
B.Se.

CONGENITAL malformations of the heart usually receive scant notice in
standard medical works. This is true not only of general text-books on
medicine, but also of works specially devoted to affections of the heart.

Such inadequate treatment of an important subject may perhaps be
explained on the assumption that these congenital malformations are
frequently regarded as mere curiosities of development; and since the
more pronounced examples are often incompatible with life, they are also
regarded as of no clinical importance.

Some of these cases of defective cardiac development are, however, quite
compatible with life. They are, moreover, sufficiently common to render
their recognition essential to the general practitioner; but a clear description
of their anatomy, combined with an account of their symptomology and of
the physical signs they produce, is yet to be written.

A mere glance at the specimens of congenital abnormality of the heart
which may be seen ranged on the shelves of any well-equipped anatomical
museum is sufficient to show that quite a large proportion were taken
from adults, or from children who had passed well beyond the age of
infancy. Of the two specimens which we shall describe, one was taken
from a woman who had reached the age of fifty.

Now, all cases of congenital malformation of the heart do not of course
present an identical clinical picture, but the symptoms will vary with the
nature of the malformation and with the degree of interference with the
normal circulation. For example, in some cases there is defective develop-
ment of the right ventricle and pulmonary artery ; and in these cases the
lungs will receive a diminished and perhaps inadequate supply of blood.
In others (e.g. one of the cases which we shall describe) it is the left
ventricle and the aorta which are ill-formed, with compensatory enlarge-
ment of the right ventricle and pulmonary artery ; and in these cases, while
the lungs receive an ample supply of blood, the body generally, including
the brain, receives a deficient supply, the blood entering the aorta through
a patent “ductus arteriosus.”

ee ge Oe at

Two Examples of Cardiac Malformation 229

___At-wiil, ‘moreover, be obvious that to relieve the various symptoms which

are produced by the several types of congenital malformation of the heart
different treatment must be employed, and more especially so according as
the pulmonary or systemic circulation is chiefly affected. It is of the
greatest importance therefore that the signs and symptoms produced by
these different. types of cardiac malformation should be carefully studied
in all cases, and recorded, so that an opportunity will be afforded of com-
parig one case with another, and of diagnosing the kind of abnormality
during life.

Classification on an anatomical basis of the different kinds of defective
cardiac development has now been satisfactorily accomplished, and the
results have been published by Keith and other writers. In order to
complete our knowledge of these cases, however, it remains for clinicians
to correlate the signs and symptoms which these different malformations.
of the heart produce. It will then be possible to recognise the type of
malformation during the patient’s lifetime, and to carry out the treatment
of individual patients upon a rational] basis.

There is one other point which we feel it necessary to emphasise before
describing these two specimens, namely, that in a very large number of
eases of cardiac abnormality which are brought to anatomists from the
“post-mortem” room, the heart has been cut away close to the origin of
the large blood-vessels, and sometimes, even, a large portion of the walls of
the auricles and the pulmonary veins have been cut away. Under these
circumstances, it is often difficult and sometimes impossible to say how the
circulation has been carried on. In all cases, therefore, in which some
congenital malformation is suspected, the relations of the large vessels
should be noted before the heart is opened, and when the heart is removed,
the arch of the aorta, a considerable length of the venz cave, and all the

_ pulmonary vessels (arteries and veins) should be removed with the heart.

Case I.
Congenital Malformation of the Left Ventricle and Ascending Aorta.

This case occurred in the practice of Dr T. G. Wilson of Adelaide, South
Australia, to whom we are indebted for the specimen. The infant became
cyanosed soon after the cessation of the placental circulation, and it died
forty-eight hours after birth. |

The specimen may be described as a three-chambered foetal heart, con-
sisting of right and left auricles, and right ventricle; the left ventricle and
ascending aorta being quite rudimentary and functionless.

The external appearance of the heart when viewed from above and

230 Dr R. J. Gladstone and Dr C. H. Reissmann

behind is represented in fig.1. The drawing shows the rudimentary ascending

aorta coursing upward behind the pulmonary artery and right auricular —

appendix. A small left coronary artery is also present which passes down
between the left auricular appendix and pulmonary artery, and indicates
the position of the anterior interventricular groove. The ascending aorta
above the origin of the coronary arteries is quite impervious.

Fig. 2 bows the cavity of the left auricle (L.Ar.) viewed from behind.
The drawing also shows the interauricular septum (S.Pr.), and widely open
foramen ovale. A minute recess which represents the cavity of the rudi-

Rudiment of aorta.
/
/
/
Pulmonary ——/2> 3, ©) 2 Bee —- — — R. auricular
artery. add appendix.
Superior

-~ vena cava

Pulmonary -
artery.

* aa
L. auricular

: “== Inferior
appendix.

vena cava,

L. pulmonary ~
vein.

R. pulmonary vein.

Casz IL, Fie. 1.

mentary left ventricle, and which is situated in the position of the mitral
orifice, will also be recognised.

In fig. 8 the heart is represented as seen from in front, the right
ventricle and pulmonary artery having been opened. The tricuspid orifice,
the infundibulum, and the semilunar valves of the pulmonary artery will
be readily recognised.

The large blood-vessels at the base of the heart were cut off close
to their origin and termination. If these had been preserved we should
probably have found an open “ ductus arteriosus,” through which the blood
coming from the right ventricle and pulmonary artery would have reached

the arch of the aorta, beyond the imperfectly developed and impervious —

ascending portion.
Similar cases of suppression or incomplete development of the left

ae

Be te ial

Two Examples of Cardiac Malformation 231

ventricle and ascending aorta have been described by Professor Arthur
Keith and Dr Eric Gardner, specimen 616.7, Museum, R.C.S., Eng. They
have to be distinguished—

(1) From three-chambered hearts in which the right ventricle and
pulmonary artery are rudimentary or absent.

In these, owing to the absence or diminutive size of the right ventricle,
and of the impossibility of the blood escaping from the right auricle through
the tricuspid orifice, the right auricle empties itself through a widely-open
foramen ovale directly into the left auricle and so into the left ventricle

F.Ov. 8.V.C.

Case L., Fic. 2.

and aorta. Part of this blood finally also reaches the lungs from the aorta
by means of a patent “ductus arteriosus ” in which the blood courses in the
reverse direction to the normal. The blood may, however, reach the pul-
monary artery by a different route, as in a case of Dr F. S. Mackenzie,
described by Professor Arthur Keith. In this heart the body of the right
ventricle was rudimentary, but the infundibular or bulbar portion and the
pulmonary artery were present. In this case the blood reached the pul-
monary artery from the left ventricle by passing successively through a
patent interventricular foramen, a narrow ostium bulbi, and the bulb or
infundibulum. During life venous and arterial blood would have mixed
in the left auricle, the former entering through the foramen ovale, the
latter entering from the pulmonary veins.

232 Dr R. J. Gladstone and Dr C. H. Reissmann

(2) They have to be distinguished from that form of three-chambered
heart in which there is a failure in the separation of the right from the
left ventricle, owing to the absence of an interventricular septum.

In these cases both right and left auriculo-ventricular orifices are present,
and open into a single common chamber, from which two large blood-vessels
emerge, the pulmonary artery and the aorta.

An interesting example of this defect was described by the late Professor
A. H. Young, in the Jowrn. Anat. and Physiol., vol. xli., 1907. It oceurred
in a man “who during the greater part of his life appeared fairly healthy,

Pulmonary artery.

R. auricular
appendix.

Tricuspid £

s -_
R. ventricle. ~

CasE. 1., Fic. 38.

and any malformation of the heart was not even suspected.” He lived to
the age of thirty-five, and was not cyanosed until shortly before his death.

In all these types of three-chambered heart there will be a mixture of
venous with arterial blood. In the case which we have described, assuming
that the “ductus arteriosus” was patent, and that the pulmonary circula-
tion had been established, the arterial blood coming from the lungs through
the pulmonary veins on entering the left auricle was unable to pass by the
usual route through the mitral orifice, and it must therefore have passed
from left to right through the patent foramen ovale into the right auricle,
where it mingled with the venous blood entering this chamber from the
superior and inferior venz cave. The mixed arterial and venous blood

Ce ty ee eT
’

Two Examples of Cardiac Malformation 233

_ then “passed through the tricuspid orifice into the right ventricle, and dis-

charged into the pulmonary artery. It reached the lungs by the right and
left branches of this vessel, and the body generally by means of the patent
“ductus arteriosus” and aorta.

The chief indications of the condition were cyanosis, dyspnoea, and the
signs of a defective systemic circulation.

Case IL.

A Heart showing a Constriction in the Position of the Ostium Bulbi,
associated with a Persistent Interventricular Foramen.

This specimen was obtained from a woman who had attained the age
of not less than fifty years. The patient was a chronic invalid, and she
had been under the care of many medical practitioners, some of whom were
experienced clinicians. Yet notwithstanding this fact, the existence of the
cardiac malformation was not diagnosed during life. On the other hand,
the patient was thought to be suffering from chronic pulmonary tuberculosis,
a view which was shown at the autopsy to have been entirely erroneous.

The heart in this case appears to be an example of an imperfect develop-
ment of that part of the right ventricle which corresponds to the “ bulbus
arteriosus” of fishes. The right ventricle, the walls of which are greatly
hypertrophied, is subdivided by a collar-like constriction into a small upper
chamber, viz. the bulb or infundibulum, and a large lower chamber corre-
sponding to the body of the ventricle (fig. 1). The opening between these
two chambers (ostium bulbi) would just admit the point of a finger. The
interventricular foramen will be seen to lie behind and below the constric-
tion, so that the blood contained in the body of the ventricle would be dis-
charged partly into the aorta through the interventricular foramen, and
partly into the pulmonary artery through the ostium bulbi. It will be
noticed also that the pulmonary semilunar valves are much thickened and
deformed by endocarditis, and that the interior of the bulbous portion of

-the ventricle is rough and granular. Attached to the posterior semilunar
valve is a large pedunculated vegetation.

Fig. 2 shows the heart opened from behind, and the cavity of the left
ventricle held open by a glass rod. The interventricular foramen will be
observed below the anterior and right posterior semilunar valves of the
aortic orifice. The foramen is bounded below by a thick rounded border,
which is roughened by endocarditis, and continuous on the right side of
the septum (fig. 1) with the anterior papillary muscle of the tricuspid valve.

The pulmonary artery is thin-walled and considerably smaller than the
aorta. In the removal of the heart the aorta was severed at the junction

234 Dr R. J. Gladstone and Dr C. H. Reissmann

of its ascending part with the arch, and the pulmonary arteries were cut
just beyond the bifurcation of the main vessel, so that the “ligamentum
arteriosum,” or the “ductus arteriosus” if this vessel had remained open,
was not preserved. It is probable, however, that sufficient blood would
have entered the pulmonary artery to maintain the pulmonary circulation,

ee ee Pulmonary
artery.
R. auricle. —-—--—-——-—---
Spglaeeene eke, Pulmonary
a valves.
| Neateieanentans i Bulb.
Interventricular ———-—-—-~- d we s yy \
foramen. rap Ai : Sa gua & bee Coniston.” ae
'
Tricuspid
orifice.
!
R. ventricle. “oe
Case II., Fie. 1. Sait

without the “ductus arteriosus” remaining patent. In cases, however,
of more complete arrest and those in which the pulmonary artery is
absent or impervious, the “ductus arteriosus” persists. (According to
Keith, in about 37 per cent. of all cases.) The blood-supply of the lungs
in these cases is thus derived from the aorta, and the direction of the
current in the “ductus arteriosus” through which the blood reaches the
right and left pulmonary arteries is reversed.

In the remaining cases, if the child has survived its birth, and the

i

= bg — en eee ee re ee al Fink. -
J 4 al a pe ea

Ce. tl See yl Se”

Two Examples of Cardiac Malformation 235

“ductus arteriosus” is closed, the lungs receive their blood from the
bronchial arteries, and from the accessory branches of the intercostal and
pericardio-phrenic arteries. (O.T. Arteria comes nervi phrenici.) These
arteries undergo a remarkable enlargement, and they are also increased in
number. Thus the existing bronchial circulation is made use of to perform

_- Interventricular
-* foramen.

Pulmonary ~-—-—-—
_-c RB. auricle.
Mitral valve
R. ventricle.
L. ventricle. ~

CasE II., Fie. 2.

the function of the pulmonary vessels, and in addition to this new channels
are opened up which do not normally exist.

The circulation thus developed is feeble, but it suffices to maintain life.

The presence of endocarditis affecting the “bulb” and the pulmonary
semilunar valves is of considerable interest. It has been supposed that in
similar cases in which unmistakable signs of a previous inflammation of
the endocardium have been present, the endocarditis occurred during the
early stages of foetal life, and has given rise to a cicatricial constriction,
and further that the interventricular foramen, so commonly present in
these cases, persists for the escape of blood whose passage through the

236 Dr R. J. Gladstone and Dr C. H. Reissmann

narrow infundibulum and pulmonary artery is restricted if not arrested.
According to Schipmann, the most common and important effect of intra-
uterine endocarditis is stenosis of the pulmonary orifice, and he also states
that the limitation of the endocarditis to the right side of the organ during
intra-uterine life comes under the same law as its limitation to the left side
in extra-uterine life. In both cases it is the cavity which has most work
to perform that is affected. According to this view, cases in which the
interventricular foramen has not persisted are produced by endocarditis
occurring after the period when this foramen is normally closed. The
closure is effected by the fusion of the interventricular septum with the
bulbar septum, and this takes place in embryos between 12 mm and 18 mm.
in length, and at the age of six to seven weeks. It is probable, however,
that the endocarditis is a secondary incident which has occurred after
birth, and that the primary condition is constriction. It is probable also
that the constriction is attributable to a primary defect in development
rather than to a foetal endocarditis; for if foetal endocarditis were the
cause, we should expect also to find stenosis of the right auriculo-ventricular
orifice with endocarditis of the tricuspid valve, but this is not found, on
the contrary congenital stenosis of the right auriculo-ventricular orifice is
extremely rare. Foetal endocarditis, moreover, does not explain thosé
cases in which there is complete obliteration of the pulmonary artery
extending as far as its bifurcation, and associated with a failure in the
expansion of the infundibular or bulbar portion of the right ventricle, such
as is present in a specimen described and figured by Professor Keith in the
Lancet of August 7, 1909, p. 361.

The persistence of the interventricular foramen is apparently secondary
to failure in expansion of the bulbar portion of the right ventricle, and
its presence, and size when present, depend largely upon the extent of
the defect.

Cases of imperfect development of the bulbous portion of the right
ventricle, or of constriction between this part and the body of the ventricle,
are not uncommon. Two specimens were described and figured by Dr
Thomas B. Peacock in his work on Malformations of the Heart, in 1866.
In one of these taken from a child aged five there was a septum in the
right ventricle, producing a marked division between the sinus and the
infundibular portion, the heart being otherwise well formed. In the second
case there was a partition between the two portions of the right ventricle,
with deficiency of the interventricular septum, and a narrow pulmonary
orifice.

The first case is of importance as it demonstrates that a defective
development of the “ bulb ” may exist without an interventricular foramen ;

PA ey ea ee ee er ry

i ee ee) a ae
i ae cS se

Two Examples of Cardiac Malformation 237

and therefore that the small size of the “bulb” and pulmonary artery are
not a secondary result of the diminished amount of blood flowing through
these parts, owing to the escape of blood through an interventricular
foramen into the aorta. Their small size is due to an arrest of the normal
developmental expansion of these parts—this being the primary defect,
and the persistence of the interventricular foramen secondary.

SUMMARY.

The first case is an example of a three-chambered heart.

There are three possible varieties of the three-chambered heart :—

(1) The two ventricles are merged into a single common chamber, the
interventricular septum being absent.

In this variety the circulation is altered only to the extent that arterial
and venous blood mix in the common ventricle, and a portion of venous
blood fails to pass through the lung and consequently remains un-
oxygenated.

(2) The right ventricle is rudimentary or absent, and the three-
chambered heart consists of right and left auricle and a left ventricle.

The circulation is completed by either one or other of the following

paths :—
(A) _ Left auricle
Left ventricle
ve ian
4 XN
Aorta Aorta
Venez cave Ductus arteriosus
Right auricle Pulmonary artery
Foramen ovale Pulmonary veins
% a
NX “
Left auricle
(B) Left auricle
Left ventricle
4 ba
Aorta Interventricular foramen
Venez cave Bulb
Right auricle Pulmonary artery
Foramen ovale Pulmonary veins
ae i

Left Auricle

(3) The left ventricle is rudimentary or absent, and the three-chambered

238 Two Examples of Cardiac Malformation

heart consists of a right and left auricle and a right ventricle. (Such a
case is described in the text.) The circulation is completed as follows :—

Right auricle

Right ventricle

a pes
Pulmonary artery Pulmonary artery
Ductus arteriosus Pulmonary veins
Aorta ~ Left auricle
Venee cave Foramen ovale ,
a 3
Right auricle

In each of these last two varieties the lung receives its blood-supply by
a collateral circulation as it were, and therefore, as in the first variety,
part of the blood remains unoxygenated.

The second case is that of a heart showing a constriction in the position
of the ostium bulbi, associated with a persistent interventricular foramen.

That portion of the right ventricle known as the “bulb” or “ infundi-
bulum” is imperfectly developed, leading in effect to a pulmonary stenosis.
The right ventricle is consequently hypertrophied and the interventricular
foramen persists.

The bulb and the pulmonary semilunar valves are affected with endo-
carditis, and the hypothesis is considered that the endocarditis is an ante-
natal phenomenon, and is in fact the “fons et origo” of the cardiac
malformation, viz., constriction of the ostium bulbi with consequent
patency of the interventricular foramen.

But while the view is accepted that the closure of the interventricular
foramen is prevented by the unequal distribution of pressure in the two
ventricles, there is ample evidence to show that endocarditis is not the
primary cause of the bulbar constriction, which may, in fact, occur in the
absence of any inflammatory change whatever.

ks Sab ie aa ad

THE THYROIDEA IMA ARTERY. By G. Wyarr. Pratt, B.A.,
St John’s College, Cambridge.

INTRODUCTION.

THis artery, which is described in all the anatomical text-books, may
arise from the arch of the aorta (arcus aorte), from the innominate artery
(a. anonyma), from the right common carotid (a. car. com. dext.), from the
right or left subclavian, and in rare cases from one of the branches of the
subclavians. It variesin diameter from ‘5 mm. to3 mm., and it may consist
only of a single trunk or of multiple bifurcations and terminal arborisa-
tions. In short, there does not seem to be any cogent reason for cata-
loguing, or even for naming, this aberrant thyroid artery. Unfortu-
nately, an element of associative importance appears—the artery is of
importance surgically in the operation of tracheotomy.

RECOGNITION OF THE THYROIDEA IMA ARTERY.

Neubauer (1) recognised the thyroidea ima, and after him it was called
the thyroid artery of Neubauer. Sappey (2) notes that the thyroidea
ima is a supernumerary inferior thyroid, that it springs from the innomi-
nate arch, and adds that it has been very rarely observed. Beaumanoir (3)
states that he has seen cases in which, with all the thyroid arteries of a
normal size, the thyroidea ima was of a large calibre and divided into
three branches, the upper two ascending and taking up their positions, the
one lateral to the trachea, the other lying in the middle line and terminat-
ing in ramifications and anastomoses with the other thyroid arteries in the
thyroid gland. The descending branch divided into two twigs, the ascend-
ing one passing upwards to terminate in the thyroid gland, while the other
descending limb passed downwards to the region of the aortic arch and
terminated in the surrounding tissue.

He noticed also in another case (4) the origin of the thyroidea ima from
the innominate artery, in the form of a branch of 2 mm. in diameter which
terminated in the sterno-thyroid muscles and subjacent tissue, and had no
connexion whatever with the thyroid gland.

Taylor and Grell (5) described a case in which, associated with the
origin of an inferior thyroid artery of normal calibre, a small thyroidea

VOL. L. (THIRD SER. VOL. XI.)}—APRIL 1916. 16

240 Mr G. Wyatt Pratt

ima was evolved from the innominate artery. Testut (6) states that the
thyroidea ima may spring either from the arch of the aorta or from the
innominate artery. He goes on to state that its presence is solely connected
with the lack of a sufficient blood-supply for the thyroid ees from its
normal sources.

Theile (7) remarked that the thyroidea ima was either a displacement
or a reduplication of the inferior thyroid artery. Macalister (8) states that
a middle thyroid artery is sometimes seen to rise from the innominate
artery and ascend on the trachea to supply the thyroid gland. |

Deaver (9), Morris (10), and Young and Robinson (11) all state that
the thyroidea ima is given off by the innominate artery, and that its sole
object is the arterial supply of the thyroid body. M‘Murrich (12) lays
down the definite precept that the presence of the thyroidea ima is
“associated with a more or less extensive reduction of the size of one or
other of the thyroid arteries.”

In my own experience I have found the thyroidea in two subjects only
during three years. In the first case the artery came off from the right
common carotid at a distance of one inch below the bifurcation and passed
first inwards, and then directly upwards for a short space, when it divided
into four trunks, all of which terminated, after supplying the thyroid
gland, in anastomoses with the arteries proper of the thyroid body. The
artery was of substantial calibre, and there was no diminution either in
diameter or in number of the normal thyroid arteries. The thyroid body
also was of the usual dimensions. In the second case the thyroidea ima
came off as a short twig from the right common carotid artery inferior to
the bifurcation. Its course was practically coincident with that of the
inferior thyroid artery, and terminated in the thyroid body.

DISCUSSION AND CONCLUSIONS.

In the face of such a conflicting mass of evidence, it would at first
sight appear difficult to formulate any definite explanation of the appear-
ance and significance of the thyroidea ima.

It is impossible to agree with M‘Murrich in the assumption that the
thyroidea ima is only developed when there is insufficiency of blood supply
—either by congenital or acquired conditions —to the thyroid body.
Unfortunately for this view, there are many cases on record where the
thyroidea ima has been observed to have no connexion with the thyroid
body at all. It is noticeable, however, that whenever these descending —
branches are present they are slender and invariably pass downwards
towards the locality of the thymus gland. This would account for the

The Thyroidea Ima Artery 241

usual extreme slenderness of the thyroidea ima when it arises from the
arch of the aorta or the lower part of the innominate. In all recorded
eases it is noticeable that the thyroidea ima when present—either as a
single branch not proceeding to the thyroid body, or as a twig passing to
the thyroid gland and evolving another offshoot coursing away in the
direction of the thymus—is universally of diminutive calibre. When the
thyroidea ima is devoted solely to the thyroid body, it is either a single or
multiple artery of large calibre. It may be associated with diminutive
development of the thyroid arteries, or, on the other hand, they may be
normal. There does not seem to be any hard-and-fast rule. In the higher
Primates, Keith (13) found on dissecting one gorilla, four gibbons, three
semnopitheques, and two macaques that in some of the last two genera
the thyroidea ima arose from the carotid artery in the neck, while in
the other cases it arose from the aortic arch. From these facts it
would seem that the thyroidea ima is just as variable in the higher
Primates as it is in man, and that it has no definite position which can
be made a precept.

In reviewing the facts at my disposal, I find the following singular
agreement. When the thyroidea ima is given off from any artery in the
region of the neck, it is usually of a noticeable diameter; when it is given
off from an artery which is not in the neck, it is invariably of slender
calibre. Against this must be set the fact that when a “neck” thyroidea
ima artery gives off a branch which descends towards the thymus, it is
always of slender dimensions. The reason for this is not far to seek. The
thyroidea ima when passing to the thymus is of very small size simply
and solely because the body to which it had formerly directed its supply
has more or less completely atrophied as a gland. It may be questioned
from this why the thyroidea ima has not altogether atrophied, considering
that its purpose in life has gone. This is easily answered. Waldeyer has
shown that total degeneration of the thymus never occurs, and that
throughout life it retains something of its old form. In this thymic con-
nexion it would be better not to call the artery thyroidea ima, but thymica
accessoria, thus giving the artery its proper significance. When the thy-
roidea ima is of large size, and passing to the thyroid body, its presence
may be due to one of two causes: (a) the absence or malformation of one
or more of the superior or inferior thyroid arteries due to defective
development of the thyroid arteries proper, or (b) the necessity of a
large blood-supply to the thyroid gland from physiological or patho-
logical causes.

It will be seen that this artery (whether in the position which justifies
the name of thymica accessoria, or in the position in which it should be

242 The Thyroidea Ima Artery

called thyroidea ima) is purely an anomalous and abnormal condition, and
does not justify its presence in anatomical nomenclature at all. M‘Murrich
(12) and Thane (14) state that the thyroidea ima is present in 10 per cent.
of bodies, but this figure would appear to be much exaggerated.

REFERENCES.

(1) Neupaver, Op. Anatom. collecta, 1786.
(2) Sappry, 7raité d Anatomie, 1869.
(3) Beaumanorr, Bull. de la Soc, Anat., tome vii., 4° sér., 316, 1882.
(4) Beaumanorr, ¢bidem, 317, 1882.
(5) Taytor and Grewt, Jour. of Anat. and Phys., vol. xxxvi, 288, 1902.
(6) Tesrut, Z'racté d@ Anatomie Humaine, tome 2™°, 151, 1900.
(7) Ture, ibedem, 151.
(8) MacauisterR, Human Anatomy, 631, 1890.
(9) Deaver, Surgical Anatomy, vol. ii. 126, 1900.
(10) Morris, Human Anatomy, 533, 1915.
(11) Youne and Rosinson, Cunningham’s Text-book of Anatomy, 888, 1913.
(12) M‘Murricu, Piersol’s Human Anatomy, 729, 1907.
(13) Kern, Jour. of Anat. and Phys., vol. xxix. 455, 1895,
(14) THane, Quain’s Elements, vol. ii. 388.

YA SSE eee Ra EY

Pe ee a ee

THE WEST SCOTTISH SKULL. By Tuomas H. Bryce, M.D.,
Professor of Anatomy, University of Glasgow.

In the anatomical department of the University of Glasgow we possess a
great series of skulls all obtained from one site. They were obtained
during the removal of an old graveyard, thanks to the zeal of Dr W. H.
Hutton, now Lecturer in Anatomy at Queen Margaret College. It was his
intention to have worked over the collection, but from circumstances
beyond his control he was unable to carry this out. Accordingly, it was
arranged that Dr Matthew Young, the Senior Demonstrator, who has an
aptitude for this class of work and a sufficient knowledge of statistical
methods, should undertake the task. The work has occupied a number of
years, and the results have now been published in the Transactions of the
Royal Society of Edinbwrgh, by aid of a grant from the Carnegie Trust.
As Dr Young desired to present the work as a Thesis for the degree of
Doctor of Medicine, publication of the individual sections of the work
has been reserved, and the whole is now presented as a complete and
intensive study of the brain case from every point of view, statistical and
morphological. The research in its progress has had special interest for
myself, and I think the memoir of sufficient importance to warrant the
presentation of a general account of the main results for the benefit of
those who have not the leisure to work over the great mass of detail
included in it.

When one first saw the whole series laid out on the floor preparatory
to a general classification of the individual specimens, one was forcibly
struck with the uniform character of the skulls. Apart from variations
in size, only one type seemed to be represented, and that obviously a
dolichocephalic type or one in the lower register of the mesaticephalic
class.

It was at once borne in on one that an almost unique opportunity pre-
sented itself for a biometrical study of the variability and correlations of
the skull. It was discovered in due course that the series satisfied Karl
Pearson’s test for homogeneity, the standard deviation for length being
5°94 and that for breadth 4°76; further, that the mean cephalic index for
male skulls was 74°41 and for female 76°03.

Here then was a long and homogeneous series of dolichocephalic type
which would yield means approaching morphological actualities, From

24,4 Professor T. H. Bryce

the papers and atlases of Berry and his co-workers in Australia there
are now available data for obtaining true means for Tasmanian and
Australian skulls. The main interest of the research on the morphological —
side came, therefore, to centre in the detailed comparison of two dolicho-
cephalic types, the one on a high the other on a low plane of civilisation,
and in the determination of the factors involved in the growth and
expansion of the bony capsule in this type of cranium as the brain
increased in size.

The total number of skulls left, after all juvenile and about 50 metopic
skulls were eliminated, was three short of 600. These were divided into
three classes: (a) male skulls, (b) female skulls, and (c) skulls of doubtful
sex. 405 skulls were found in class (a), 100 in class (b), and the remainder
in the doubtful class. These last were eliminated from the research,
although the measurements are included in the appendix to the memoir.
Of the 405 male skulls 100 were selected for special morphological analysis,
and they were ultimately divided in the sagittal plane for estimation of the
spheno-ethmoidal and other angles.

‘The large proportion of male to female skulls may raise a doubt as
to the correctness of the identification of sex, which is of course notoriously
difficult in many cases. It is possible that most of the doubtful skulls-
should have been classed as female, but the correctness of the classification
is supported by the fact that there is no great difference in the means in
the complete male group and the more stringently selected group of
100 male skulls, in which the male characteristics were specially well
marked. It is clear, however, that in making this selection the larger
skulls were unconsciously chosen, as the mean capacity of the group is
50 cc. in excess of that of the whole male series.

The first section of the memoir embodies a comparison by ordinary
craniological methods of the West Scottish with Sir William Turner’s
series of Scottish skulls. It was found that although in all essential
particulars the West Scottish skulls were identical in their characters
with Turner’s Renfrewshire group, the series differed from his complete
series in having a distinctly lower mean width. In short, the brachy-
cephalic element which Sir William Turner showed to exist in
appreciable numbers in the population of Scotland is practically absent
in our collection.

While 20 per cent. of Turner’s skulls had an index of 80 and upwards,
only 3°7 per cent. of our 505 skulls had indices rising to that level. Further,
85:5 per cent. had indices below 77:5, and of the 14°5 per cent. of skulls
left only 3:7 per cent. had indices of 80 and upwards, while only ‘4 per cent.
had indices greater than 82:5. In the specially selected series 92 per cent.

The West Scottish Skull 245

- had indices below 77°5; and only one skull, with an index of 80°9, rose into

the conventional brachycephalic category.

The female group had a slightly greater tendency towards brachy-
cephaly, with a mean index of 76:03. Ten skulls had indices over 80,
but only one an index over 82°5. This and another skull were the only
specimens which could be said to be true brachycephalic skulls. Compari-
sons between male and female skulls are instituted in the paper at some
length, but here attention will be confined to the male group and to the
data for the calvaria only.

The mean lengths in the two series differed by a millimetre only in
favour of the West Scottish series. The mean basi-bregmatic heights were
only fractionally different, but Turner’s series exceeded the other by 5 mm.
in mean breadth. The West Scottish skull has a mean capacity well up to
the average of other European races, viz. 1459-4411 in 405 males. The
selected series had a mean capacity of 15113486, the highest yielded by
any other of the groups brought into comparison. The mean cephalic index
of this group is 74:36 against 74°41 for the complete series. This shows
that increase in capacity has no appreciable effect on the cephalic index.
The series conclusively disproves the claim of greater capacity for brachy-
cephalic skulls.

The maximum length in the male is greater than in any other series
—European or otherwise—save the Whitechapel series described by Mac-
donnell, in which the mean was greater by a couple of millimetres. The
mean of 405 male skulls was 187°52+°20, compared to 183-44 and 183°56
in the Tasmanian and Australian respectively.

The mean breadth is less, considerably, than it is in any other European
series, viz. 139°56-++ 16, but greater than it is in dolichocephalic lower races
The Tasmanian breadth is 136-69+"44, and the Australian 130-6036.

The mean basi-bregmatic height in 405 male skulls was 132°72+'17,
a relatively low figure. It is practically equal to the mean of the
Whitechapel series, is slightly greater than it is in French and German
skulls, but less than it is in modern Negroes, the Aino and Naquada
races. The mean is practically equal in the West Scottish and Tasmanian
skull, and only 3 millimetres greater than in the Australian.

There are only fractional differences in the basi-nasal lengths in the
European series. In the lower races, as is well known, the basi-nasal
length is absolutely greater than in the higher races, and this holds for

- the West Scottish as compared with the Tasmanian or Australian skull.

It follows from a consideration of the absolute measurements of the
three main diameters that the West Scottish skull is longer, narrower,
and lower than any of the Continental types available for comparison in

246 Professor T. H. Bryce

series; but, compared with the skull of the Tasmanian or Australian, it
is longer, distinctly broader, and slightly higher, the basi-bregmatic height
being taken as the measure of height.

The female skull is in the mean less capacious than the male, and the
proportions maintaining between length and breadth are such that the
female skull rises into the mesaticephalic category with a mean index of
76-0319.

The next section of the paper deals with the variability of the West
Scottish skulls. A consideration of the data brings out the following as the
most salient points: in all save 10 out, of 49 characters—viz. cephalic index,
height index, height-breadth index, palato-maxillary index, length of the
occipital segment of the sagittal are, basi-alveolar length, alveolar and nasal
angles—the male skull showed greater variability than the female. In
respect of nasal width, asterionic breadth, and basilar angle the variability
was equal in both sexes. The series thus supports the older view regarding
variability in the sexes, not the newer view of Karl Pearson and others that
the female shows greater variability than the male.

Confining our attention to the larger series of male skulls, the coefficient
of variability in the case of the capacity is relatively higher than in any.
series yet examined for this factor. The West Scottish skull is the least
variable in length among other European series. It is less variable in
respect of this character than the Australian, and equals in variability
the Tasmanian skull. The coefficient for breadth is higher than the
coefficient for length, but it is distinctly less than in the other European
series ; it is equal to the coefficient for the Tasmanian skull, but markedly
greater than that for the Australian. Height shows a slightly lower
degree of variability, and again the West Scottish and Tasmanian skulls
closely correspond, while this time the Australian skull shows a higher
degree of variability. 3

Although there are a number of exceptions, the general impression given
by the tables is that the coefficients of variation are generally less than
they are for the corresponding characters in other European series, and
approximate to the values given for purer series such as the Tasmanian
or Naquada. Where the Australian is included in the series it shows,
except in the case of breadth, a higher degree of variability for the
several characters than the West Scottish skull.

All this speaks for the uniform character of the series, and it demon-
strates that. the variability may be on the whole less, or as low, in a uniform
series representing a race on a high level of civilisation, as in one on a low
grade of culture. The higher degree of variability usually predicated for
the higher races is probably a matter merely of admixture,

The West Scottish Skull 247

——
——

In the next section, on the correlation of the West Scottish skull,
Dr Young shows that the male is more highly correlated than the female.
In this his results are not in full accord with those of Pearson and Lee, but
as the writer is not competent to judge the question on the mathematical
side, the points on which the correlations touch the morphological side will
be alone dealt with.

When the three main dimensions were cobvelnies it was found that in
both sexes length and breadth show the highest, and breadth and height
the lowest correlation. When one dimension increases there is a tendency
to increase in the other dimension correlated with it.

The series furnishes additional evidence against the “law of compensa-
tion.” There is no evidence to show that, say, a breadth above the average
is compensated by a height or length below the average. This may
possibly, to some extent, apply when different skull forms are compared,
but in a uniform series it does not hold at all. In the West Scottish series
the maximum length and maximum breadth, as one would expect when
basi-bregmatic height is the third factor, have a greater correlation to
capacity than height, and breadth has a higher correlation to capacity
than length. Minimum frontal width has an equal correlation to maximum
length and to maximum width, showing that as the diameters increase all
the dimensions enlarge.

The correlations of capacity to the cephalic and vertical indices are very
small, and in some of the series compared with our own are actually
negative. In the West Scottish series a slight positive correlation of
‘091-033 in the case of the cephalic index points to a very slight tendency
towards brachycephaly, with increase of capacity. The series, however,
affords no support, other than this, to Thomson’s “elastic capsule” theory,
nor to Lee’s thesis that increase in capacity is associated with a greater
emphasis of the form typical of the race. In our series the selected group
of skulls with greater capacity has a mean cephalic index only fractionally
less than the whole male group.

One of the most interesting points in this section of the paper is the
demonstration of the part played by the occipital bone in expansion of
the sagittal arc. The correlations are worked out for the sections of the
are to the total arc, and to the maximum length of the skull. It seems
that, of the three, the occipital section has the highest correlation to the
total arc. In other words, when the are of the skull increases it is the
occipital section which is responsible to the greatest degree for the increase,
then follows the frontal, and then the parietal. The same holds for the
female series, but in the female skull, while the correlations of the frontal
and occipital sections are less than in the male, the correlation of the

248 Professor T. H. Bryce

parietal to total arc is equal in the sexes. In the same way the inter-
parietal part of the occipital has a higher correlation to maximum length
in the male, though apparently not in the female skull, than the frontal
and parietal sections of the sagittal are.

The correlation values are all comparatively low in the West Scottish
series, a fact pointing to an infinite variety of minor differences or
refinements of skull form in such a homogeneous series; because, as
Dr Young says, it is apparently possible to have an alteration in a
certain dimension with only a comparatively slight, though in most cases
sensible, tendency to a corresponding increase in another dimension.

The remaining sections of the work comprise. an elaborate morpho-
logical analysis of the characters of the cranial vault. For this purpose
the methods of Klaatsch and Schwalbe were applied to the selected group
of 100 male skulls. The only complete data available for comparison
are those provided for us for the Tasmanian and Australian skull by Berry
and his co-workers. Klaatsch’s method has been applied to only one series
of sufficient length, viz. to the Tasmanian skull, by Biichner, but Dr Young
has worked out the data for the Australian skull on the profile outlines
supplied by Berry and Robertson in their atlas. Professor Berry, in_
supplying other workers with this series of dioptrographic tracings, has
done valuable service to craniology, and he has added to the obligation
by granting in advance to them the free use of the figures. In Klaatsch’s
original description of his scheme of measurements, which is of course only
an elaboration of older methods with less imposing names, he compared
some individual Australian and European skulls, and reached conclusions
which have not been confirmed in all respects by larger-series of skulls.
It must again be emphasised that Dr Young was working with the mean
values of a homogeneous series of skulls dolichocephalic in type, and of
large capacity. The comparison is instituted between this and the mean
values of a series of skulls also dolichocephalic but of small capacity. The
results might have been different had his series been brachycephalic in
type, for it is probable that the factors involved in growth and expansion
are different for this form of cranium.

Klaatsch took the glabella-lambda line as his horizontal base line, and
found that when the basi-bregmatic line was drawn in on a sagittal contour,
it cut this line at an angle of about 90° (fig. 1). In the Australian skull
the angle varies from 84° to 94°, with a mean of 89°45°; in the Tasmanian
the mean is 896°. In the Scottish series the angle varies from 87° to 100°,
with a mean of 92°5°. The most frequent angle was 91°, and it occurred
21 times out of 100.

In the following abstract the comparison of the Scottish with the

YP ael Pe. ee ee

The West Scottish Skull 249

_ Australian skull will be specially considered, but exactly the same

results would come out in the case of the Tasmanian. The series from
which the Australian means were derived was a mixed one containing
a small proportion of female skulls. Dr Young separated the figures
for the male skulls from those of the complete series in the case of
Schwalbe’s scheme, but not in the case of Klaatsch’s method. The differ-
ences are merely fractional, and I shall here take the figures for the
complete Australian series, for the sake of uniformity. It is the compara-
tive, not the absolute, dimensions that are important. The glabella-lambda
line is 75 mm.; the glabella-inion line 2°83 mm.; the maximum breadth
10 mm.; the basi-bregmatic height 3°7 mm.; the calvarial height 8:2 mm.
greater in the Scottish skull. The frontal chord length is 48 mm., the
glabella-bregma chord 5°3 mm. longer in the Scottish skull, but the parietal
chords are practically equal in the two types. The lambda-basion line is
85 mm. longer in the Scottish skull, but the basion-glabella lines are
approximately the same. The lambda-inion chord is as much as 12°7 mm.
longer than in the Australian skull.

In the Scottish skull the height of the frontal are is 216; of the
parietal are 23:3; of the occipital arc 9-7; and the corresponding figures for
the Australian skull are 19-3, 22°9, and 5°7.

The frontal-are index (Gas oe for the Scottish skull is

19°5, the parietal-arc index is 20°3, the occipital 148, while the corre-
sponding figures for the Australian are 18-1, 20-2, and 10°9.

As far as these dimensions are concerned, the most striking differences
between the Scottish and the Australian brain-case lie in the hinder part
of the vault. The frontal bone is longer and more curved in the Scottish
skull, the parietal bones are nearly identical in length and curvature, but
the interparietal part of the occipital is much longer and more curved than
in the Australian It will be remembered that this part of the occipital is
more highly correlated to the total sagittal are and to maximum length
than either frontal or parietal.

Schwalbe’s bregma and lambda angles each exceed by 2° the corre-
sponding angles in the Australian, but the mean upper glabella angle of
Klaatsch’s figure is smaller in the Scottish skull. The total mean angles
are nearly equal (74°4° to 749°), but there is a difference in the size of the
components, the upper glabella angle being the larger in the Australian,
the smaller in the Scottish skull. The total lambda angle is more acute
in the Scottish skull, and its upper component is also more acute. The
angle at the bregma is more obtuse by 2° than in the Australian, while the
angles at the basion are equal or nearly so,

250 Professor T, H. Bryce

Lastly, the upper segment of the basi-bregmatic height is in the mean
slightly less than the segment below the glabella-lambda line in the
Scottish skull, while the opposite relation holds in the Australian. Now,
if the central points be supposed to coincide, and the glabella-lambda line
be taken as the base, and presumed to present the same inclination to the
horizontal plane in both skulls, the low vault of the Australian skull would
lead us to expect that the angle at the bregma would be more obtuse and
the upper glabella and lambda more acute than in the Scottish skull, while

/
Br

Fic. 1.—The sagittal contour of the mean Australian skull superimposed on that of the mean West
Scottish skull, with Klaatsch’s inscribed figure, the glabella-lambda line being taken as a
common base and the central points made to coincide.

Continuous line =Scottish mean. Interrupted line= Australian mean.

the part of the height above the glabella-lambda line would be less than
the lower segment. In the present case, however, the West Scottish skull
takes in all these particulars the position that should be occupied by the
Australian, and the Australian the place which should be occupied by the
Scottish skull.

The reason for this is explained by the two diagrams. Fig. 1 shows
the two mean contours and the contained polygons superimposed on the
glabella-lambda line. The glabella-lambda arcs are very similar, and
the height is the same in both; the centrum angle is greater in the
Scottish skull, and the bregma is rather further back, The inion of the

Ge ae Pe

ata i ee 3

The West Scottish Skull 251

_ Scottish contour is considerably depressed below the inion of the Australian

contour, and the basion lies below and in front of the corresponding point
in the Australian.

Fig. 2 shows the two contours superimposed on the glabella-inion line.
It demonstrates how in the West Scottish skull the increase in the inter-
parietal part of the occipital has raised the lambda, has uplifted and
carried forward the bregma, so that the basi-bregmatic lines have become
parallel and cut the glabella-lambda lines at nearly the same angles. The

Fic. 2.— The same contours as in fig.1, with their inscribed figures superimposed, the glabella-inion
line being taken as a common base. The calvarial heights are also indicated.

Continuous line=Scottish mean. Interrupted line= Australian mean.

elevation of the lambda has given the glabella-lambda line a different
inclination than in the Australian contour, and this in turn explains how,
while Schwalbe’s bregma angle is more obtuse in the Scottish skull, both
upper glabella and upper lambda angles of Klaatsch’s figure are more
acute; and also how the angle at the bregma is more obtuse and the
upper segment of the height shorter in the Scottish cranium.

The outstanding result that emerges from a comparison of the two
figures is that the calvarial height measured from the glabella-lambda line
is nearly the same in both types, and that the increase of the true calvarial
height in the Scottish skull is due entirely to the increase in length of the
lambda-inion factor. If we imagine the more capacious dolichocephalic

252 Professor T. H. Bryce

Scottish brain-case as the terminal phase in the expansion of a lowly, less
capacious skull with the same mean dimensions as those of the Australian,
we find that with increased capacity the parietal width has increased by
about a centimetre and the length has increased by about 5 mm., due to
the bulging of the part of the occipital bone related to the occipital lobes
of the hemispheres. ‘The elongated shape is retained, but as the increase in
width is greater than in length the cephalic index is somewhat raised. The
frontal and occipital regions have expanded with the parietal width, so
that the norma verticalis presents a full oval outline. The basi-bregmatic
height has enlarged by 3 mm. only, but the calvarial height, placed well
back, has expanded by nearly a centimetre. With a general elevation of the
vault, the greatest expansion has taken place not in the frontal but in the
posterior part of the brain-box.

Translating these facts into terms of the brain, we may conclude that
with a general expansion of the cerebral hemispheres there has been a
specially great increase, and more particularly in depth, of the posterior
parieto-occipital regions ; and in explanation one’s thoughts at once turn to
the great co-ordinating field between the tactile, visual, and acoustic areas,
the expansion of which has been responsible, as Elliot Smith has shown,
for the pushing back and over on to the medial surface of the visual field
in the human brain.

Those who are acquainted with the type of dolichocephalie skull
represented in this West Scottish series are of course familiar with the
fulness and depth of the hinder part of the brain-case and the promi-
nence of the occipital probole, but this new demonstration of the factors
involved in the growth and expansion of the dolichocephalie vault is
important and suggestive.

Klaatsch’s claim for the gin bellis-lambaa line as a suitable horizontal
base is not substantiated, and it has been demonstrated how comparatively
similar the supra-glabella-lambda arcs are in the Scottish and Australian
skulls. The uplifting of the vault has involved no expansion of the
antero-posterior length of the parietal bone; a certain increase has occurred
in the length and curvature of the frontal bone; a large increment has
taken place in the length and curvature of the interparietal part of the
occipital bone. It should be understood that these results apply only to
the dolichocephalic form type, and that other factors may, indeed must,
be involved in the growth and expansion of the brachycephalic form type
of skull.

The next section of Dr Young’s paper reveals some striking facts,
perhaps the most important of the points raised by his work. All the
skulls of the selected series of 100 specimens were divided by a fine saw cut

The West Scottish Skull 253

_ inthe median plane. I believe no such long series of sagittal sections has
been before examined and compared. The various angles were recorded,
and Bolk’s method for the determination of the position and inclination
of the foramen magnum applied.

In this account I shall only refer to the results obtained respecting the
spheno-ethmoidal and foramino-basilar angles. The results in respect of
the first-named angle came rather as a surprise to me, but I can vouch
for the correctness of the work, as I tested in nearly all the specimens the
dimensions of the angle directly on the sections, and got the same figures
as Dr Young did on his impressions.

In the first place, two outstanding types of base were met with, the flat
and the steep. The spheno-maxillary angle varied from 136° to 170°, and
the mean value was 152°35°, with a standard deviation of 658 and a
coefficient of variation of 4:32. The range of variation is great, and the
angle a relatively obtuse one. In some cases the angle was as great as
the angles given for anthropoid skulls. Dr Young points out that a
large angle might be reasonably assumed for a long basi-nasal length,
and specimens were obtainable which illustrated this; but, on the other
hand, other skulls, with approximately the same basi-nasal length, were
found to show an angle diminished even to the extent of 34°. Two skulls
were observed with the same glabello-occipital and basi-nasal lengths, but
with spheno-ethmoidal angles differing by more than 20°. He worked
out the correlations between the angle and basi-nasal length and maximum
length, and discovered a very slight but positive correlation to basi-nasal
length but not to maximum length, although, as had been shown earlier,
there was a high correlation between the maximum and _basi-nasal
lengths. It may be noted that the nasion was used as the anterior
extremity of the ethmoidal factor in the angle, and no doubt it is sub-
ject to some variation. The spheno-ethmoidal junction is also subject
to variation, but in no case can the magnitude of the variation of the
angle be explained by variations in the position of these two points.
The wide differences in the angles are quite obvious, indeed striking, to
the eye.

The foramino-basilar angle similarly varies within wide limits, having
a range from 135° to 168°, with a mean of 14768° The difference
between the two angles being 4°6°, the mean flexure of the cranial base
falls short by that amount of 180°. The significance of this great range
of variation of these angles is not obvious, and the subject wants further
working out. In light of the results all comparative figures for the
angles will require reconsideration. The slope of the foramen magnum
is very variable, but, worked out according to Bolk’s method, the mean

254, The West Scottish Skull

inclination forwards in the Scottish skull is less than in the Negroes
examined by that author. It may be added that Dr Young has given
some data regarding the thickness of the skull wall at various points.

A word in conclusion regarding the affinities of the West Scottish
skull. As Dr Young points out, the skulls, as far as their main features
are concerned, might be either Mediterranean or Teutonic. They most
closely resemble, however, in all their characters the type of skull known
as the long-barrow skull, and all the archzeological and other evidence
is in favour of the view that they represent the Mediterranean type of
cranium which spread into our islands in the late Stone Age. The west
of Scotland seems to have remained relatively true to the skull form of
the early occupants of Dalriada, and this series is a local deposit, as it
were, in nearly pure condition, of the primitive type of cranium.

THE ARTERIES OF THE PONS AND MEDULLA OBLONGATA:
Part Il. By J.S. B. Sroprorp, M.D., Lecturer in Anatomy, Univer-
sity of Manchester.

PART II.

THE PRECISE DISTRIBUTION OF THE ARTERIES SUPPLYING THE
MEDULLA OBLONGATA AND PONS.

ALTHOUGH our knowledge of the gross anatomy of the bulbar branches
of the vessels of the hind brain has hitherto been far from complete, it
is vastly superior to the information we possess of the regions of the
medulla oblongata and pons which these arteries supply.

Heubner (73), Duret (54), Kolisko (85), and particularly Beevor (19),
have provided us with a considerable amount of information of the
cortical and basal distribution of the cerebral arteries; and almost every
anatomical text-book describes, in great detail, the precise blood supply
of the fore brain. Alezais and d’Astros (5) have studied most carefully
the vessels which supply the mid brain. As previously stated, the blood-
vessels of the spinal cord have been fully considered by Marie (95),
Obersteiner (102), Kadyi (82), Adamkiewicz (2), and Ross (115).

Yet the exact blood supply of the hind brain, by comparison, has been
left in obscurity to this day; and no English manual of anatomy even
attempts to unravel its mysteries, although its importance to the modern
neurologist cannot be overestimated. This work, however, has not been
wholly neglected, but within recent years it has become increasingly
evident that the subject requires reinvestigation to elucidate the pro-
blems of clinical medicine. Enormous advances in our knowledge of the
structure and functions as well as in the pathology of the central nervous
system have been made since the arterial supply of the medulla oblongata
and pons was last studied, and the importance and urgent desirability
of further information are becoming more and more obtrusive. Our
present knowledge is wholly due to the researches of Duret (55) and
Adamkiewicz (2).

Duret’s memoir was published more than forty years ago, when
histological methods were very imperfect and the localisation of tracts
was quite in its infancy. He made only twenty injections, and his
attention was directed primarily to the radicular arteries. No attempt

VOL. L. (THIRD SER, VOL. XI.)—APRIL 1916. 17

256 Dr J. S. B. Stopford

was made to define the areas of the medulla and pons supplied by
the individual vessels. Adamkiewicz, over twenty years ago, covered the
same ground as Duret in his researches, but only advanced our knowledge
by supplying a more detailed account of the course of the minute nutrient
arteries within the bulb.

Both of these observers examined most carefully the. small vessels
supplying the cranial nerves, and traced their ramifications peripherally
and centrally; but their work was essentially descriptive, for the know-
ledge of the structure and functions of the brain was not sufficiently
extensive at that time to suggest the clinical significance such researches
might have. This is another reason why it has failed to satisfy the
demands of present-day neurology.

These two published accounts create the impression that the distribu-
tion of the arteries of the hind brain is extremely constant, and almost
completely ignore the question of variation in supply.

The unsatisfactory state of our knowledge is manifest in almost every
treatise or memoir on vascular lesions of the pons and medulla, and is the
explanation of much of the vagueness in references to the subject when
attempts have been made to explain the obscure etiology of so many
bulbar diseases. Even if a greater knowledge did not prove of very great
assistance in determining the etiology, it would at any rate prevent irre-
levant allusions by which the physician and pathologist are able to throw
the responsibility for their ignorance upon the unfortunate anatomist.

TECHNIQUE.

About fifty injections in all have been made; but some of the earlier
ones were not very satisfactory owing to defects in technique, which
were remedied as the work progressed. At first it was intended to adopt
completely Beevor’s (20) method, in which he used a system of pressure
bottles, and injected simultaneously several vessels. But this was not
found to be feasible, owing to the small calibre and delicacy of many
of the arteries in this region; instead, it became necessary to make the
injections with a record syringe.

Beevor adversely criticises this method for the cerebral arteries, but
it has been repeatedly proved, in the case of the arteries of the hind
brain, that the resultant varying pressure did not cause any material
inaccuracy in the field of injection. Even when two neighbouring vessels
were injected, there was never the slightest confusion of the two colours
along their line of contact. This fact lends support to the accepted

opinion that the nutrient vessels to the pons and medulla oblongata are
true “ end-arteries.”

The Arteries of the Pons and Medulla Oblongata 257
Jenti and d’Alundo (146) studied the terminal branches of the

erebral arteries in mammals, especially the cat and the rabbit, and
nd that they anastomosed during intrauterine life, but after birth

WZ —Pest- Guahrck
— Sup, Cnabellan

Fic. 6.—Method used for injection of I. basilar artery, IL. vertebral artery,
IIL. anterior spinal artery.

cations existed in the human fcetus during the third and fourth
nonths of foetal life.

ry As an essential preliminary to injection, the arteries were washed free
fr r \ blood with saline solution. After the necessary ligatures had been

|

258 Dr J. S. B. Stopford

of the stain, the needle was tied into the vessel and the brain placed in
hot water in order to prevent, the injection-fluid setting. In making the
injection considerable pressure had to be exerted, and maintained for
some time, if a complete and successful result was to be obtained. This
was especially necessary in the case of the basilar — which proved
to be much the most difficult to inject.

After withdrawal of the needle, the ligature fixing it was immediately
tied to prevent escape of the stain, and the brain fixed in formalin for at
least forty-eight hours.

After fixation, the bulbar or pontine branches were carefully studied
and noted, as well as the anatomical disposition of the other vessels as
described in Part I.

When the cerebellum had been removed, the stained portion of the
floor of the fourth ventricle was accurately mapped out in diagrammatic
form; and then serial sections of the medulla and pons were cut, figured,
and mounted in order.

The sections were cut about one-sixteenth to one-eighth of an inch
thick, and were fixed on sheets of glass.

Soluble colours in gelatine, as described by Beevor (20), were used for
the injections.

Red and blue were chosen because they exhibit such a marked coiieane
and the latter colour proved to be particularly satisfactory in the case of
small areas, as its definition was so very clear.

Red. Carmine, 4 drachm. Blue. Nicholson’s blue, 15 grains.
Ammonia, }_,, Alcohol (90 per cent.), } ounce.
Glycerine, } ounce.

In both cases dissolve, and then add to 2 ounces of gelatine dissolved in
1 pint of hot water.

Beevor (in 1907) was the first to employ soluble colours in his investi-
gation of the cerebral vessels, but this method has never been adopted for
the arteries of the pons and medulla; the greater accuracy obtained by
using soluble colours, in preference to suspended insoluble powders, is
quite obvious, and is referred to in Beevor’s classical paper. Beevor claimed
that all the colours, except the yellow (which has not been used in this
work), were absolutely fixed by the formalin. My own specimens, although
mounted in formalin, tend to fade slightly and lose their sharp definition
at the periphery of the injected area; and I hear that the same difficulty is —
at present being experienced with Beevor’s magnificent specimens in the
Museum of the Royal College of Surgeons.

The Arteries of the Pons and Medulla Oblongata 259

_

The Anterior Spinal Artery.

The bulbar distribution of this vessel is confined to the anterior and
median parts of the medulla oblongata, and, owing to its remarkable
constancy, it has been found preferable to consider it first, in order to
simplify the descriptions of the less regular inconstant ones.

From the results of the seven experiments quoted by Moxon (100), there
is good reason to conclude that the anterior spinal fills from above down-
ward—a fact of considerable significance when clinically determining the
result of its occlusion. The only variations in its distribution depended
upon either an unusually low origin from the vertebrals (20 per cent. on
the right and 13 per cent. on the left), or extreme caudal fusion of these
two vessels, which was noted in 19 per cent. These two factors only
influence the level of the upper limit of the area supplied, and in both
cases cause the distribution to be less extensive when traced in a cephalic
direction. In either instance the vertebral is found to compensate for the
deficiency and to supply the region normally vascularised by the anterior
spinal as the pons is approached.

In consequence of the diminutive size of the anterior spinal some
difficulty was found in injecting it, which rendered it necessary to insert
the needle at the junction of the two vertebrals, after applying ligatures
below the origin of the artery under investigation. Thus the upper part
of each vertebral was injected in addition to the anterior spinal. After
ascertaining the’area supplied by the vertebral in subsequent experiments,
it was possible to eliminate that part of the medulla it supplied, and in
that way obtain the exact distribution of the anterior spinal alone (see
fig. 6).

Floor of the Fourth Ventriele.

Invariably the trigonum hypoglossi was accurately defined by the stain
of the injection.
Spinal Cord.

In a number of injections it was possible to see the distribution to the
first cervical segment of the spinal cord.

The grey matter of the anterior cornua and around the central canal
was deeply stained; whereas the white matter of the ventral columns and
the region of the anterior roots was stained a much paler colour. In
addition, in about 50 per cent. the base of the posterior cornua was also
injected. The median branches (set B) appeared to supply the grey inatter,
whilst the transverse rami (set C) provided smaller branches which ramified
in the white matter and terminated in the grey matter; but their precise

260 Dr J. S. B. Stopford

anatomical arrangement and course within the cord have been admirably
studied previously by others.

The more intense staining of the anterior cornua indicates its rich
blood supply, which has been demonstrated by Ross (115) and subsequent
observers.

The above description is in perfect agreement with the opinion of
Kadyi (82), Adamkiewicz (3), Obersteiner (102), and Marie (95), but, in
addition to the support it lends to their work, it also gives a clearer and
probably more accurate conception of the region supplied by the anterior |

Pie

Fic. 7.—Floor of fourth ventricle.

system of spinal arteries; because the observations are made before it
becomes obscured by the anastomoses between the anterior and posterior
systems, which occur below this level. In the investigation of the distri-
bution of the anterior spinal to the cord, this vessel has never been injected
as far as the point where it communicates with the posterior spinal, and
consequently the stained area must strictly represent the district supplied
by the former vessel alone.

This subject is somewhat controversial, and often rendered obseure by
many writers in their endeavour to divide the cord into three districts—_
first the part supplied by the anterior system, secondly the part supplied
by the posterior, and lastly the area supplied by both. The latter, accord-

The Arteries of the Pons and Medulla Oblongata 261

ing to Kadyi, approximately amounts to one-third of the transverse area
of the cord.

Level of Pyramidal Decussation.

The median set of bulbar branches can be seen with a lens to turn
obliquely in a dorsal direction amongst the decussating fibres, which they
supply as far back as the crossed pyramidal tract, where they terminate.
The detached head of each anterior cornu and the grey matter surrounding
the central canal, as well as the ventro-lateral ground bundles, the nucleus

Fic. 8.—Cervical spinal cord. Fic. 9.—Decussation of pyramids.

and tractus solitarius, Gower’s tract, and (of course) the remains of the
pyramid were also supplied. The latter two were chiefly dependent upon
the smaller perforating branches of the transverse rami.

Level of Sensory Decussation.

The area of distribution at-this level was very similar to the previous
one; the only additional structures supplied were the internal arcuate
fibres as they cross the middle line to form the medial lemniscus, and
the nucleus of the hypoglossal nerve.

Calamus Region.

Here the district supplied by the anterior spinal was limited laterally
by the fila of the hypoglossal nerve as they passed to their superficial
origin, and dorsally by the nuclei of the posterior columns, which were
never included. At this level the dorsal nucleus of the vagus, in addition
to the hypoglossal nucleus, pyramid, medial lemniscus, tecto-spinal tract,
and medial longitudinal bundle, was within the injected area, but the
tractus solitarius was usually situated laterally to it.

262 Dr J. 8. B. Stopford

Mid-Olivary Region.

In this section the ventral part of the inferior olive with the olivo-
cerebellar fibres, as they passed out of the hilum to reach the opposite

Fic. 10.—Normal distribution of anterior spinal artery.

inferior cerebellar peduncle, and the medial accessory olive were supplied,
as well as the structures supplied in the calamus region. That is to say,
at this level the pyramid, hypoglossal nucleus, ventral part of the inferior
olive, and the whole of the formatio reticularis alba on each side are
supplied by the anterior spinal.

The Arteries of the Pons and Medulla Oblongata 263

~~“There was every indication that the median branches formed a network
and richly supplied the hypoglossal nucleus, as described by Duret. The
majority passed dorsally, through the lemniscus, to this nucleus, but a
certain number turned into the hilum of the inferior olive, the ventral _

Fic. 11.—Normal distribution. Mid-olivary region.

part of which they were found to supply. The transverse set provided
shorter branches, which penetrated the pyramids and the ventral external

_ arcuate fibres, even to a point just dorsal to the antero-lateral sulcus.

The upper group of branches (set A), as described in Part IL., formed
a plexus on the upper part of the pyramids, and supplied a similar area to
the parent vessel, above its origin from the vertebrals.

Upper Olivary Region.

Hitherto it has been found unnecessary to refer to the variations
signified at the outset of the description of the distribution of this artery.
Normally the anterior spinal continued to supply the same region as
described in the previous section as far, in a cephalic direction, as the level
of the entrance of the auditory nerve, at which point it was replaced by
the vertebral. In cases of low origin of the anterior spinal, or where the
site of junction of the two vertebrals was considerably below the inferior
border of the pons, the former artery was found to supply the bulb only as
far as a point somewhere between the lower border of the pons, and the
upper third of the olivary eminence. The exact level of this point
obviously depended upon the extent of the variation in the two factors
which have been stated to affect its distribution.

Under no circumstances was the anterior spinal found to supply any
region above the level of the lower border of the pons, or, in other words,
no injection is to be seen in a transverse section displaying the strie

sf

264 Dr J. S. B. Stopford

medullares ; but their position is so liable to variation that it is preferable
to adopt the first method of description.

Normally, in the cephalie direction, the distribution of the anterior
spinal became slightly reduced, and was gradually replaced by bulbar
branches of the vertebral (set A) and the basilar.

- It is instructive to note that the hypoglossal nucleus, the origin of
nerves, primarily spinal, which later became cranial, is supplied by the
_ anterior spinal artery.

The Vertebral Artery.

In the early part of the work this vessel was injected from above,
but, owing to the imperfect injection of the most cephalic set of bulbar
branches by this method, it was found advantageous to insert the needle
of the syringe below, immediately above the place where the artery nee
pierced the dura.

The distribution of this artery was subject to very considerable varia-
tion, which has been found to depend upon three factors :—

1. Variation im the distribution of the posterior inferior cerebellar
artery.— Attention has already been drawn to the fact that the |
vertebral replaces the bulbar branches of this vessel when it is
absent or fails to provide any nutrient twigs for the supply of

- the medulla, and compensates almost invariably for their in-
sufficiency. The effect of this will be shown to be most obvious
in the olivary region. .

2. The origin of the anterior spinal artery.—When this vessel arises
at the level of the lower extremity of the olive, or below that
point (20 per cent. on the right and 13 per cent. on the left), the
vertebral has to compensate for its deficient supply to the most
cephalic part of the medulla.

3. The level of the junction of the two vertebral arteries.—When the
junction occurs some distance below the caudal border of the pons
(19 per cent.), the distribution of the vertebral and anterior spinal
is curtailed, and that of the basilar increased; whereas, in cases
where the junction was distinctly above this point (8 per cent.),
the area supplied by the vertebral was increased, with a corre-
sponding decrease in that supplied by the basilar.

The latter two factors will influence the cephalic limit of distribution.

The percentage variation in the distribution of the vertebral, together |
with the factors which cause it, is of enormous clinical interest, and helps
to elucidate many of the outstanding difficulties that arise in connection

The Arteries of the Pons and. Medulla Oblongata 265

with the localisation of the occlusion of vessels in this region. Attention
must be directed again to the division of the bulbar branches of the vertebral
into three sets (upper, middle, and lower), as a clear conception of their
arrangement makes the involved description somewhat less complex.

Floor of the Fourth Ventriele.

The injection always demarcated the trigonum vagi and, usually, the
trigonum hypoglossi in the neighbourhood of the striz acustice. There

Fic. 12.-—~Floor of fourth ventricle.

was rarely some extension to the trigonum acustici and the inferior part
of the colliculus facialis. The staining of the latter region was only
seen in cases where the two vessels united cephalic to the lower borders
_ of the pons.

Level of Pyramidal Decussation.

At this level the most caudal set of branches have been seen to enter
the lateral region of the medulla. They are found to supply a triangular
interval having its apex towards the central canal, which was bounded
ventrally by the detached head of the anterior cornu and decussating
fibres, and dorsally by the funiculus cuneatus.

This area included the spino-cerebellar tract, remains of the posterior
cornu, substantia gelatinosa of Rolando, nucleus and tractus spinalis

266 Dr J. S. B. Stopford

nervi trigemini, and a few of the fibres which formed the lateral cerebro-
spinal tract.

When the posterior spinal arose from the vertebral (on the right in 18
per cent. and on the left in 20 per cent.), and was also injected, the funiculi _
gracilis and cuneatus with their nuclei were also stained ; and consequently

L~

Fic. 13.—Decussation of pyramids.

the whole area of the medulla, at this level, was supplied by the vertebral
arteries and their two spinal branches. It is quite inconceivable that such
a widespread occlusion could occur clinically.

Level of Sensory Decussation.

The distribution here was very similar to that seen in the previous
section, only the tract of Gowers was also supplied, as, at this level, it is
found to be situated in a more lateral position, owing to the oecupation of
the ventral region by the motor fibres.

Calamus Region.

Here the area supplied was the same as the above, with the addition of
the nucleus and tractus solitarius, in those cases in which they did not lie
within the anterior spinal district (see p. 261). Hitherto no variation of
any moment has been described, unless we include the posterior, spinal,
which is, strictly speaking, a separate artery with a definite distribution of
its own, and the supply has been provided practically by the caudal set of
bulbar branches.

Mid-Olivary Region.

At this level the study is restricted to the distribution of the middle
set of vessels, composed of branches passing chiefly to the postero-lateral
sulcus. They are the branches which vary according to the distribution of

The Arteries of the Pons and Medulla Oblongata 267

the—posterior inferior cerebellar artery, and consequently considerable
variation in the vertebral supply is to be expected.

When the posterior inferior cerebellar freely provided branches for the
retro-olivary region, the area supplied by the vertebral was represented by
a narrow “wedge” between the anterior spinal district medially and that
of the posterior inferior cerebellar dorso-laterally. This wedge included
the medial and ventral parts of the formatio reticularis grisea, the dorsal
half of the inferior olive, and frequently the dorsal vago-glossopharyngeal
nucleus. The injected portion of the formatio reticularis grisea included
the fasciculus tegmento-olivaris, the olivo-cerebellar fibres, and the dorsal
accessory olive.

The wedge increased in size proportionately to the decrease in the

Fic. 14.—Absence of posterior inferior cerebellar on right. Mid-olivary region.

area supplied by the posterior inferior cerebellar, so that, in the absence of
the latter vessel, the whole of the dorso-lateral region of the bulb was
dependent upon the distribution of the vertebral. The significance of
the percentage variation in distribution of the posterior inferior cerebellar
now becomes manifest. According to the figures stated, some increase
in the area supplied by the vertebral, at this level, was to be found in
36 per cent. on the right, and 32 per cent. on the left; but in the vast
majority of these the posterior inferior cerebellar failed to provide any
bulbar branches, so that in 31 per cent. on the right and 29 per cent. on the
left the vertebral was found to supply the whole of the formatio reticularis
grisea in this region. Therefore, in the latter number, the vertebral also
supplied the spino-thalamic, rubro-spinal, and the anterior and posterior
spino-cerebellar tracts, as well as the nucleus ambiguus, descending root
of the vestibular nerve, nucleus and tractus spinalis nervi trigemini, and
a large part of the inferior cerebellar peduncle. This variation, dependent
upon the distribution of the posterior inferior cerebellar, will be main-

268 Dr J. S. B. Stopford

tained as far as the pons; but, for brevity, future reference to it will
be omitted.
Upper Olivary Region.
We now gradually come to the consideration of the upper set of
bulbar branches.

Fic, 15.—Normal distribution of vertebral artery.

From this level the wedge-shaped area was seen to increase medially
owing to the diminishing anterior spinal district, and laterally at the
expense of the posterior inferior cerebellar district, when traced in a
cephalic direction. The whole of the inferior olive was supplied, and

PS oh ae! Tee

ae eee

The Arteries of the Pons and Medulla Oblongata 269

the moré lateral part of the pyramid, together with an increasing amount
of the formatio reticularis grisea. At this level normally a considerable
amount of the inferior cerebellar peduncle was supplied by the vertebral,
and consequently the diminishing posterior inferior cerebellar district was
situated between two parts of the area supplied by the former artery.

Lower Border of the Pons.

Normally, at the most cephalic limit of the medulla, the vertebral
completely replaced the anterior spinal and posterior inferior cerebellar
arteries. So that, in addition to the whole of the formatio reticularis |
alba, including the medial lemniscus, dorsal longitudinal bundle, tecto-spinal

Fie. 16.—Variation dependent upon low origin of basilar (19 per cent. ).

tract, and the most cephalic part of the hypoglossal nucleus were also
almost entirely supplied by the vertebral. Consequently, just at this
level, practically the whole of the medulla was supplied exclusively by
the upper set of bulbar branches from the two vertebral arteries. _

Provided the arteries maintain what is described as their normal ar-
rangement, the only structures ever to be found outside the vertebral
district were the inferior cerebellar peduncle, which may be supplied by
the posterior spinal or posterior inferior cerebellar, the most medial portion
of the pyramid supplied by the anterior spinal, and perhaps more
frequently a small part of the retro-olivary region supplied by the posterior
inferior cerebellar artery.

The above account is only for the normal arrangement and distribution,
and even that is not quite constant; the two factors which cause variation
in the vertebral supply in the upper part of the medulla have still to be
considered. From the foregoing it can be seen easily that abnormally

270 Dr J. S. B. Stopford

low origin of the anterior spinal will cause the vertebral to take over
at a lower level, and consequently more completely, the supply of the
pyramid hypoglossal nucleus and the tracts contained in the formatio
reticularis alba.

The low junction of the two vertebrals, unless the origin of the anterior
spinal is abnormally low (an association which is of extreme rarity), will
result in the basilar replacing the anterior spinal. Consequently, in 19 per
cent. the vertebral failed to supply the pyramid, hypoglossal nucleus, and
formatio reticularis alba, and its occlusion would not cause hemiplegia,
asis generally thought to be the inevitable result of such a lesion.

When the vertebrals fused abnormally high (8 per cent.) they replaced the

Fic, 17.—Variation dependent upon low origin of anterior spinal.

basilar caudally, and supplied the pyramidal bundles and medial lemniscus
in the pons, together with the abducent nucleus and fibres of the facial nerve.
The more caudal part of the abducent nucleus has been supplied occa-
sionally by the vertebral in cases where this vessel terminated normally
at the lower border of the pons. The specimens produced strong evidence
to support the opinion that the terminal ramifications of the median bulbar
and pontine branches spread out and run for some distance, in a cephalic
direction, in the grey matter of the floor of the fourth ventricle. This
is indicated by the persistence, repeatedly, of some injection in this situa-

tion in sections cut cephalic to the lower border of the pons, 7.e. the upper

limit of the normal distribution (see fig. 15).
The only alternative to this supposition is that the median vessels do

not run directly dorsally, but incline slightly in a cephalic direction as —

they pass towards the floor of the fourth ventricle.
The deep staining of the nuclei in the floor of the fourth ventricle

—
+h hg
ee

eee

The Arteries of the Pons and Medulla Oblongata 271

supported the opinion expressed by previous writers that there is a
: vascular network in this situation, which is formed by the terminal
: ramifications of the median nutrient branches from the various arteries.

The Posterior Inferior Cerebellar Artery.

Considerable attention has been directed to this artery, first, because
of its increasing clinical importance, and secondly, because our unsatis-
factory and incomplete anatomical knowledge of its distribution demands
revision and additional research. It has long been known that it supplied
branches to the retro-olivary region of the medulla, but even Duret and
subsequent anatomical observers have failed to determine the precise
extent of, or variation in, its distribution, as it is only during recent years
that it has sprung into such remarkable eminence.

Eight years ago Burrows, at Thomas’ (140) instigation, made some
injections to illustrate its distribution, but neglected to study the variation
in its supply: although reference to the literature on the subject of the
clinical manifestation of its occlusion demonstrates clearly that its distribu-
tion cannot be constant.

For a similar reason, Wallenberg’s (148) study of this artery fails to
provide the necessary knowledge which modern neurology demands.
Anatomical research alone can explain the discrepancies in the sympto-
matology of the numerous reported cases of occlusion of the posterior
inferior cerebellar artery.

Reference to Part I. will show how frequently the vessel was absent,
and how commonly (31 per cent. on the right and 29 per cent. on the
left), when present, there was an absence of bulbar branches to the retro-
olivary region. Furthermore, in 5 per cent. on the right and 3 per cent.
on the left it will be seen that these branches were inefficient, and only
entered the agost caudal part of the postero-lateral sulcus, and consequently
| small area of the bulb. This variation has been seen
y upon the course of the artery, as it curves round
reach the inferior surface of the cerebellum. The other
which influenced its distribution was the origin of the
inal artery, which arose from the posterior inferior cerebellar
cent. on either side.
xcluding the distriet. supplied by the posterior spinal, the usual
tribution of the vessel under consideration is confined to the limits of
inferior olive. The majority of its bulbar branches entered the postero-
* lateral sulcus, but some certainly penetrated dorsal to this point and

F passed into the inferior cerebellar peduncle. These branches did not
i 3
ae

VOL. L. (THIRD SER. VOL. XI.)—APRIL 1916. 18

272 Dr J. S. B. Stopford

appear to bear any marked relation to the vagus and glossopharyngeal
nerves, as indicated by Duret, although some might be termed “radicular.”

Mid-Olivary Region.

This is the most typical section in which to see the district it supplies,
as the latter is at its maximum, and decreases when traced from this point
in either a caudal or a cephalic direction.

laterally, where the tegmento-olivary tract invariably intervened,
medially by the fibres of the hypoglossal nerve. Dorsally its limits

not so well defined. Usually the ventral part, at least, of the inferi
cerebellar peduncle was injected, and frequently part of the dorsal vago-~.
glossopharyngeal nucleus and a small portion of the descending root of
the vestibular nerve. Thus it was seen that the posterior inferior cerebellar _

5
ao

Ba

i ena Res iS

The Arteries of the Pons and Medulla Oblongata 273

artery, at this-level, supplied most of the formatio reticularis grisea—all

except that part included in the vertebral district. Consequently its

obstruction will affect the spino-thalamic, anterior spino-cerebellar, and
rubro-spinal tracts, the olivo-cerebellar fibres, as well as the dorsal nucleus,
or fibres, of the glossopharyngeal and vagus nerves, nucleus ambiguus, and
the more ventral part of the inferior cerebellar peduncle. When the artery
maintained its more normal course and distribution, the nucleus and
tractus spinalis of the trigeminal nerve were also invariably supplied.
This is in contradiction to the opinion expressed in an early paper (30),
but more extensive investigation has proved that the spinal nucleus and
tract are only excluded from the posterior inferior cerebellar district when
the bulbar branches of this vessel are reduced in number, as a result of
its more irregular course.

The variation at the mid-olivary level, and the compensatory increase
of the area supplied by the vertebral, have been fully considered with the
distribution of the latter vessel.

Above and below the level considered, the posterior inferior cerebellar
district became gradually reduced ; in the former direction it was replaced
by the vertebral and basilar, and in the latter by the vertebral alone. It
is important to note that it is the more central part of the formatio
reticularis grisea which is persistently injected in both directions, and
consequently the spino-thalamic and rubro-spinal tracts and the nucleus
ambiguus were supplied most extensively by the posterior inferior cere-
bellar artery.

The Posterior Spinal Artery.

The small size of this vessel prevented its separate injection. But,
owing to its very constant distribution, it was easily possible to appreciate
its own district when it was injected along with either the posterior in-
ferior cerebellar or vertebral arteries. It arose from the former in 73 per
cent. and the latter in 27 per cent., but appeared to be frequently absent,

_ when it was usually replaced by supernumerary short bulbar branches

from the vertebral.

Normally it has been seen to bifurcate into an ascending ramus, which
was somewhat inconstant, and a descending ramus, which commenced the
tortuous posterior spinal chain.

The descending ramus supplied the funiculi gracilis and cuneatus with
their nuclei, and in all cases where the branch was present this distribution
was found to be absolutely constant. The ascending ramus was more
variable. It usually supplied the caudal and dorsal part of the inferior
cerebellar peduncle, but, in addition, occasionally provided branches for

a,

/

274 Dr J. S. B. Stopford

the descending root of the vestibular nerve and the trigonum_acustici.
In the absence of the ascending ramus, small branches from the descending
limb of the posterior inferior cerebellar arteries replaced its supply for
the inferior cerebellar peduncle and part of the descending root of the
vestibular nerve.

From the foregoing accounts it will be seen that the blood supply of
the inferior cerebellar peduncle is both complex and subject to very con-
siderable variation. Caudally (at its origin) it was normally supplied
ventrally by the posterior inferior cerebellar, and dorsally by the posterior
spinal. Usually in the cephalic direction both arteries were replaced
gradually by the vertebral and, to a less extent, by the basilar.

Fie, 19.—Normal distribution of posterior spinal.

Quite frequently the anterior inferior cerebellar, or even the internal
auditory, provided for the inferior cerebellar peduncle a few branches,
which merely augmented those supplied by the other vessels, and which
were not of the same clinical importance as the latter.

The Basilar Artery.

More failures have occurred in the injection of this artery than in any
of the others. This was apparently due to the greater difficulty ex-
perienced in removing the blood from the numerous small pontine branches,
and the considerable and prolonged pressure required to inject satisfactorily
the perforating branches of the transverse pontine rami.

The only factor which materially affected its distribution was the

The Arteries of the Pons and Medulla Oblongata 275

variation~in the level of its formation by the two vertebral arteries.
This has been very fully discussed previously.

:
| | Floor of the Fourth Ventricle.

The strive acusticze and that part of the ventricular floor situated
cephalic to them were usually stained.
The colliculus facialis on each side, and the most medial part of the

Fic, 20.—Floor of fourth ventricle.

floor, were supplied by the median pontine branches, and the more lateral
parts by the perforating branches of the transverse rami.

Frequently the more medial part of the trigonum acustici was in-
jected in addition. When the vertebral arteries fused some distance
below the caudal border of the pons, the most cephalic part of the
trigonum hypoglossi was also stained.

Upper Limit of the Medulla.

Normally the medial part of the pyramids and the ventral portion
of the formatio reticularis alba were injected; but if the level of the
formation of the basilar was caudal to the more usual point, this artery

276 Dr J. S. B. Stopford

was found to have replaced completely the vertebrals. In a few cases
where the posterior inferior cerebellar supplied inefficient bulbar branches
to the upper part of the postero-lateral sulcus, the basilar was found
to replace it at this level, and consequently supply the whole of the for-
matio reticularis grisea, and the inferior cerebellar peduncle.

Obviously the various pontine branches of the basilar must, practically
alone, supply under normal conditions the whole of the pons; consequently
it will only be necessary to describe separately the distribution of the

Fie. 21.—Upper limit of medulla.

median and transverse sets, instead of continuing the method adopted
for the other arteries.

The median set supply the structures immediately lateral to the
middle line in the tegmental part, and the greater proportion
of the pyramidal bundles and transverse pontine fibres in the
basilar part as well as the more medial part. of the corpus trape-

- zoidum.

The injected portion of the tegmental part will include the nuclei
of the abducent trochlear and oculo-motor nerves, and the fibres
of the facial nerve which are in such intimate relation with the
former, the medial longitudinal bundle, the medial lemniscus,
and the tecto-spinal and thalamo-olivary tracts.

The perforating branches from the transverse set supply the more
lateral parts of the pons.

Within their field of injection are to be found: the brachium pontis, —

lateral part of the corpus trapezoidum, superior olive, and the nuclei
of the fifth, seventh, and eighth cranial nerves.

ie et A ae i inal, ly

ee ee ee
l i AY e259

ee

The Arteries of the Pons and Medulla Oblongata 277

__In-19 -per cent. the origin of the basilar was abnormally low, and

consequently it replaced the vertebral above, and supplied the pyramids,

formatio reticularis alba, and the most cephalic part of the hypoglossal
nucleus, as well as a variable part of the lateral portion of the upper
medulla.

In 8 per cent., owing to the cephalic origin of the basilar, it failed to
supply the caudal part of the pons, including the facial and abducent
nuclei.

Anterior Inferior and Superior Cerebellar Arteries.

No definite distribution to the pons can be given in the case of either
of these two vessels.

The former often assists the posterior inferior cerebellar by providing
branches for the upper and dorso-lateral part of the bulb, which supply

a variable part of the inferior cerébellar peduncle and the descending

Fic. 22.—Pons.

root of the vestibular nerve. It frequently gives a variable number of
branches to the lateral and caudal part of the brachium pontis, as it passes
on to the inferior surface of the cerebellum.

The superior cerebellar artery has been shown, by Alezais and d’Astros,
to supply branches to the region of the inferior colliculus, but it also fre-
quently gives a few branches to the lateral and cephalic part of the
brachium pontis, although no precise area of distribution can be defined.

278 Dr J. S. B. Stopford

SUMMARY.

1. The anterior spinal supplied—

(a) In the cord :

(1) Anterior and base of posterior cornua.

(2) Grey matter around central canal.

(3) White matter of ventral columns and region of anterior
roots.

(b) In the medulla :

(1) Pyramids.and pyramidal decussation.

(2) Medial lemniscus and tecto-spinal tract.

(3) Dorsal longitudinal bundle.

(4) Hypoglossal nucleus (except cephalically).

(5) Nucleus and tractus solitarius (at decussation).

(6) Gowers’ tract (at decussation).

(7) Dorsal nucleus of vagus (at calamus region).

(8) Olivo-cerebellar fibres as they cross the middle line.

(9) The internal and ventral external arcuate fibres with
nucleus. }

2. The vertebral supplied—

(1) Few pyramidal fibres at formation of lateral cerebro-spinal
tract.

(2) Pyramids at the lower border of pons, and a variable part
of the lateral part’ below.

(3) The whole of the ventral part, and the cephalic portion of
the dorsal part, of the inferior olive.

(4) The dorsal accessory olive.

(5) Tegmento - olivary tract and olivo-cerebellar fibres in
formatio reticularis.

(6) Generally the dorsal vago-glossopharyngeal item above
the calamus region.

(7) Most cephalic part of hypoglossal nucleus.
(8) Nucleus and tractus solitarius (at calamus).
(9) Nucleus and tractus spinalis nervi trigemini (at decussation). .

When it replaced the posterior inferior cerebellar it also supplied :—
the spino-thalamic, rubro-spinal, and anterior and posterior spino- —
cerebellar tracts, nucleus ambiguus, descending root of the vestibular
nerve, and nucleus and tractus spinalis of the trigeminal nerve, as well

C—O

The Arteries of the Pons and Medulla Oblongata 279

_as- part of the inferior cerebellar peduncle. In 8 per cent., owing to
the high level of fusion to form the basilar, the vertebral supplied
the abducent and facial nuclei as well as the other more medial
structures in the lower part of the pons.

3. The posterior inferior cerebellar supplied—

(1) Spino-thalamic tract.

(2) Rubro-spinal tract.

(3) Olivo-cerebellar fibres as they passed to inferior cerebellar
peduncle. ;

(4) Dorsal vago-glossopharyngeal nucleus or the emerging fibres
of the vagus and glossopharyngeal nerves.

(5) Nucleus ambiguus.

(6) Nucleus and tractus spinalis of trigeminal nerve.

(7) Ventral part of inferior cerebellar peduncle.

4. The posterior spinal supplied—

(1) Funiculi and nuclei gracilis and cuneatus.

(2) Caudal and more dorsal part of the inferior cerebellar
peduncle.

(3) Oceasionally part of the descending root of the vestibular
nerve.

5. The basilar supplied—
(a) Medial set of pontine branches :

(1) Abducent nucleus and trochlear nucleus.
(2) Oculo-motor nucleus (caudal part).

(3) Medial longitudinal bundle.

(4) Medial lemniscus.

(5) Teeto-spinal tract.

(6) Thalamo-olivary tract.

(7) Transverse pontine fibres.

(8) Medial part of corpus trapezoidum.

(b) Transverse set of pontine branches :

(1) Brachium pontis.

(2) Lateral part of corpus trapezoidum.

(3) Superior olive.

(4) Facial nucleus.

(5) Remaining nuclei of eighth nerve.

(6) Remaining nuclei of fifth nerve (including motor nucleus).

280

The Arteries of the Pons and Medulla | Oblngata.

When the origin of the fighting’ was abnormally low (19°
supplied the pyramids, medial lemniseus, tecto-s
longitudinal bundle, and most menial ene the $e hypigoma

caudal portion of the brachium pontis and cee and «
limits of the medulla.

portion of the brachium pontis,

iw sHemorian,

PrincipaL Str WILLIAM TURNER, K.C.B., F.R.S., Etc.
1832-1916.

THE eve of the Jubilee year of this Journal is sorely clouded by the
lamented death of our Senior Editor. As the few survivors (if there
be any besides myself) will recollect, the project of founding the Journal
originated with him. Some of his earlier papers were published in
the Natural History Review, and the demise of that periodical in
1865 left the way open for a special Journal for the publication of
papers on Anatomy and Physiology. ;

During the committee meetings preliminary to the British Associa-
tion at Nottingham in 1866, at which Humphry presided over the
Physiological Section, Turner enlisted Humphry’s support for his
scheme, and they took into their counsel two of the editorial staff
of the defunct review, Newton and Perceval Wright, and also, at
Professor Humphry’s suggestion, John Willis Clark. At that meet-
ing all the arrangements were finally completed.

Turner was keenly interested in promoting the success of the
Journal. Visiting Edinburgh in that year, I found him occupied in
preparing the first number. We spent some time together in compil-
ing a list of names of those who might be asked to contribute papers.
He was then thirty-four years.old, but looked older. Already he had
made his mark in anatomical literature, and was regarded as the
coming leader among British anatomists. That position he certainly
occupied during the larger part of the last half century.

Although his name will be hereafter always associated with
Scotland, and especially with the Edinburgh School, Turner was
English by birth and education: a native of Lancaster, where he was
born in 1832, and a student at St Bartholomew’s from 1850 to 1854.
That, on his transplantation to Scotland, he easily and rapidly
assimilated to his new surroundings is not really surprising, for the
difference between the people of Northern England and those of the
Lothians is rather one of environment than of race.

During his student days at Bart’s he had attracted the notice of

282 In Memoriam: Principal Sir William Turner

Sir James Paget, who was sponsor for his first paper, on “ The Cerebro-
spinal Fluid,” published in the Proceedings of the Royal Society for
1854. In that year the Edinburgh Professor of Anatomy, John
Goodsir, passed through London, returning from a long sojourn on the
Continent, and took the opportunity of consulting with Paget as to
the selection of an assistant. On his recommendation, Goodsir chose
Turner (who had in 1853 obtained the M.R.C.S.) for the post. He
had also been awarded honours in Chemistry at the London University,
where later he graduated M.B. in 1857.

The young demonstrator early showed his aptitude for research,
and, in the interval between his appointment and the foundation of
this Journal, had. written nineteen papers on many branches of the
Science—Anomalies of Muscles, Histology of Nerve, the Pancreas,
Variations in Vertebre, Fossil Human Crania, ete.

Owing to the ill-health of Professor Goodsir most of the teaching
of Anatomy fell to the share of the demonstrator, and his reputation
soon spread far beyond the bounds of the University as an able, keen,
thorough, and systematic teacher. He had, by nature, that royal gift
of being able to recognise his students when he met them out of class: ~
no mean power when the numbers with which he had to do are
considered. ,

Goodsir died in 1867, and Turner was triumphantly elected as his
successor. There were two other candidates, but the result of the
election was a foregone conclusion. This chair he held for thirty-six
years, during which he raised the Anatomical School of Edinburgh
to the rank of the foremost, as well as the largest, in Britain.

Another side of his character soon showed itself. He had estab-
lished his reputation as a researcher and as a teacher, but it became
obvious to all associated with him that he was also an accomplished
man of affairs. Being returned by the Universities of Edinburgh and
Aberdeen as their representative on the General Medical Council in
1873, it was not long before his fellow-councillors recognised that he
had a clear perception of, and a sound judgment concerning, the
several problems with which the Council had to deal. As a testimony
to his qualities as a wise statesman and a systematic and judicious
man of business, he was elected by the Council, in 1898, as their
President, and continued to hold that office until 1905.

In 1903 the Principalship of Edinburgh University became
vacant by the death of Sir William Muir, and the Board of Curators

Photo by Elliott & Fry.
PrINcIPAL Sin WILLIAM TURNER,
K.C.B., M.B., F.R.C.S. L.andE., LL.D,, D.C.L., D.Sc., F.R.S.,
Knight of the. Royal Prussian Order Pour le Mérite.

—s ee,

In Memoriam: Principal Sir William Turner 283

showed their wisdom by electing Sir William Turner to fill the
post. No better appointment was ever made, The thirteen years
during which he presided over the University were, until the
outbreak of the war, years of prosperity and advance, The great
new buildings for the Medical School and the M‘Ewan Hall are the
best material testimony to the success of his work in the promotion
of its interests.

While he was thus sustaining his great name as an administrator
and statesman, he still continued to contribute many and valuable
additions to the literature of anatomical research, It is needless to
specify these individually, They are known to all readers of this
Journal, I may especially mention those on anthropology, placenta-
tion, cranio-cerebral topography, the anatomy of cetacea and of
sharks. His last great work on Scottish anthropology was published
in 1915. In recognition of his scientific contributions to knowledge
he was elected a Fellow of the Royal Society in 1877, He received
the honour of knighthood in 1886, and was created K,C.B, in 1901,
the year after he had been President of the British Association, He
also received the Prussian Order pour le Mérite.

This is not the place to recount the very long catalogue of
honorary degrees and honorary memberships of foreign and colonial
societies which were his. Few names are more widely known, as
there is scarcely any part of the world in which his students are
not to be found, He easily held the record of being the greatest
of our educators of the anatomical teachers of the English-speaking
world; at least nineteen of his students became Professors of
Anatomy or of kindred subjects in Britain, America, Australia,
South Africa,and other countries. ‘This success was partly due to
the reputation of the Edinburgh Medical School, which for many
years has numbered among its professors some of the most distin-
guished authorities in almost every subject of the medical curriculum,
partly to the fact that Scottish medical graduates are numerically
preponderant in our colonies and dependencies; but largely to the
systematic, clear, and methodical character of his teaching, which was
so widely appreciated that electors to teaching posts naturally gave
preference to those that had been his pupils <An_ interesting
testimony in this respect was the great Festschrift edited by Professor
Cunningham, the Textbook of Anatomy, in which the eleven sections
were written by eleven of Sir William’s former demonstrators,

284 In Memoriam: Principal Sir William Turner

For the last twenty years he has looked old, although hale and
fairly active. For some years he had found it beneficial to spend
part of the winter in the south of Europe, where the conditions of
climate were less rigorous than they are in Edinburgh. In a letter
written to me late last year he expressed his regret that he could
not go to Italy this winter. He was, however, able to discharge his
official duties until a few days before the end. At a meeting of
Senators on February 3 he felt unwell, and returned home before
the conclusion of the meeting. The illness gradually became more
serious and troublesome gastric symptoms appeared. He passed
away quietly in his sleep on February 15.

Even to the end he retained his interest in the Journal, and
every sheet of each issue passed through his hands before going to
press. ‘To all who knew him his death is a sore personal grief.

A. M.

SS OSS” CU

,
:
:
b
4
_

JOURNAL OF ANATOMY AND
| PHYSIOLOGY

SUR LA STRUCTURE DU POUMON DU DAUPHIN (DELPHI-
NUS DELPHTS). Par le Dr José Martins Barposa, Assistant
WVhistologie « la Faculté de Médecine de Pérto (Portugal).

(Travail du laboratoire d’histologie de la Faculté de Médecine de Montpellier.)

LE poumon du Dauphin présente des particularités de structure macros-
copique qui ont déja été signalées,’ mais il offre aussi un certain nombre
de points intéressants d’anatomie microscopique, sur lesquels je désirerais
attirer dés maintenant l’attention. Ces points sont les suivants:

I. La présence de sphincters bronchiques.

II. Le mode de ramification des bronches terminales,

I. SPHINCTERS BRONCHIQUES.

Les sphincters bronchiques, dont la présence chez le Dauphin m’a été
signalée par M. le Professeur Vialleton, qui m’a conseillé d’en faire l'étude,
sont de petits anneaux musculaires lisses placés réguliérement les uns a la
suite des autres, dans les bronches de petit calibre.

Ces sphincters qui n’ont été décrits que je sache par aucun auteur, et
quil ne faut pas confondre avec les tres délicats sphincters décrits par
Rindfleisch 2 A l’entrée des conduits alvéolaires chez certains animaux, sont
trés nombreux et tres développés chez le Dauphin.

Pour les bien voir, il faut absolument faire des coupes paralléles a la
direction générale des bronches, c’est-a-dire dirigées sur le poumon d’avant
en arriére. Les coupes perpendiculaires 4 l’axe du poumon ne donnent
que des mauvais résultats 4 ce point du vue, ce qui s’explique du reste

1 Voir comme description d’ensemble :

Cuvier, G., Lecons d’anatomie comparée, 2° éd., 1840, tome vii. pp. 101 et suivantes.
Owen, Richard, On the Anatomy of Vertebrates, Vol. iii, Mammals, 1868,
pp. 578 et swiv.
Bouvier, Les Cétacés soufflewrs, “'Thése d’agrégation de l’Ecole Supérieure de
Pharmacie de Paris,” 1889, pp. 57 et suiv.
Oppel, Lerbuch der vergleichenden mikroskopischen Anatomie der Wirbeltiere,
Sechster Teil. Atmungs apparat. :
* Rindfleisch, cité par Oppel, loc. cit., p. 653.
VOL. L. (THIRD SER, VOL. XI.)—JULY 1916, 19

286 Dr José Martins Barbosa

aisément, On sait en effet que les bronches chez le Dauphin ont principale-
ment une direction cranio-caudale, Elles divergent fort peu les unes des
autres et s'unissent sous des angles trés aigus.

Lorsqu’elles ont atteint un diamétre un peu inférieur 4 un millimétre, ces
bronches examinées 4 |’ceil nu sur un poumon durci par le formol, montrent
sur les coupes longitudinales, une lumiere presque entiérement obliterée de
distance en distance par des festons saillants, qui se font face.

C’est la manifestation macroscopique des sphincters comme on s’en rend
tres bien compte par la suite. —

Apres un certain nombre de ces sphincters, huit 4 dix, la bronche se divise
brusquement en un bouquet de bronches plus petites, qui, contrairement aux
rameaux précédents, divergent assez fortement les unes des autres et se diri-
gent d’abord perpendiculairement pour prendre ensuite une direction & peu
prés paralléle a celle du trone d’origine, de maniere que les conduits bron-
chiques présentent dans ce moment une direction en baionnette (fig. 1, A).

Les sphincters se continuent dans toute la portion coudée des conduits
bronchiques et disparaissent un peu plus loin sur les bronches terminales.

Les derniéres bronches sur lesquelles on trouve encore des sphincters,
ont un peu moins de la moitié du diamétre de celles qui montrent les —
premiers sphincters. En effet ces derniers s’observent sur des rameaux
bronchiques dont le diamétre, mesuré au dehors du cartilage, est en
moyenne de 0°7 mm.—sept-dixiemes de millimetre—tandis que les plus
petites bronches a sphincter ont un diametre correspondant a trois ou
quatre dixiemes de millimetre—03 mm. a 0'4mm. On verra un peu plus
loin que les bronches terminales sont un peu plus larges.

On comprend aisément par 14 que seules les coupes paralléles a la
direction des conduits bronchiques auront chance de montrer les sphincters
dans leur distribution réguliére, et par suite de faire bien comprendre leur
disposition et leur signification, tandis que des coupes transversales, ne
montrant que des sphincters isolés, et le plus souvent mal orientés dans
la coupe, n’attirent point l’attention.

Le plus stir moyen de suivre bien exactement dans les coupes le trajet
des conduits bronchiques est de s’adresser 4 des points du poumon ot les
bronches cheminent dans une mince lame pulmonaire qu’il est facile de
couper parallelement 4 ses faces.

Ces lames minces du poumon s’observent sur la face ventrale de lorgane
au voisinage du bord tranchant; elles ont été signalées par divers auteurs
et Konigstein! en a donné en 1903 une figure assez exacte quoique trés
schématique. .

* Konigstein, Hans, “ Notiz zur einer Cetaceenlunge (Delphinus Delphis), Anat, Anz,,
Jena, No. 23, 1903, Bd, xxii, Ss. 497-500, Fig. 2.

“ra Sur la Structure du Poumon du Dauphin (Delphinus Delphis) 287

e ___Les sphincters siégent dans I’épaisseur de la muqueuse bronchique
a: immédiatement au-dessous de |'épithélium qu’ils soulévent fortement et qui
a s’amincit &leur niveau. Ils sont donc placés en dedans des cartilages et plus
exactement entre deux anneaux cartilagineux consecutifs.

7

Fic. 1.

A.—Coupe paralléle & la surface de la paroi amincie du poumon,

br.e.d., bronche extrémité distale; br.e.p., bronche extrémité proximale; cart., cartilage; ch.br.,
chambres bronchiques circonscrites par les sphincters; ép.br., épithélium bronchique ; n.sph., neeud
de sphincters ; sph., sphincters ; sph.t., sphincter coupé tangentiellement.

B.—Bronche coupée transversalement pour montrer un sphincter.
eart., cartilage ; 7., lumiére au centre du sphincter ; sph., sphincter.

On sait depuis longtemps que les cartilages des grosses bronches forment
chez les cétacés, des cercles complets, ou plus exactement une spire continue
dont tous les tours se touchent presque. Cette spire se décompose en
segments comprenant chacun deux tours complets et se terminant 4 leurs

288 Dr José Martins Barbosa

extrémités en pointes, qui s’accolent aux extrémités correspondantes des
segments adjacents, pour former avec eux la spire continue. Cette disposi-
tion se poursuit jusque sur les petites bronches et elle ne s’arréte qu’au
point ot paraissent les premiers conduits alvéolaires, sans que pour cela
le cartilage disparaisse complétement comme on le verra plus loin.

Au niveau des bifurcations, le cartilage en spirale se complique par la
présence de plaques larges en forme d’écusson ou de croissant de maniére &
constituer partout un revétement cartilagineux solide, ne laissant aucune
partie un peu développée de l’arbre bronchique dépourvue de cette formation
de soutien.

Les sphincters musculaires siégent toujours, comme il a été dit, entre
deux cartilages consécutifs, mais comma leur épaisseur est assez considérable
ils empiétent parfois un peu sur les cartilages voisins.

Chaque sphincter est formé par un anneau de fibres musculaires lisses
disposées transversalement et fait une saillie assez forte dans la Jumiére
bronchique, qu il rétrécit par places au point de loblitérer a peu pres
complétement. Entre les fibres musculaires existe un réseau fin de fibres
elastiques bien mises en evidence par l’orcéine, et quis épaissit considérablement
sur la face libre de l’anneau musculaire. Ce réseau élastique sphinctérien
se poursuit aussi sur les cdtés et va se continuer d’une part avec les réseaux
élastiques enveloppant les cartilages, d’autre part avec les formations
élastiques du tissu conjonctif dont Max Weber a fait remarquer la richesse
particuliére chez les cétacés.1

Dans la bronche représentée, fig. 1, A, le sphincter le plus étroit que
jai mesuré avait exactement 62 w de diamétre intérieur, et le plus large
mesurait 280 ~; la moyenne de la largeur des sept sphincters représentés
dans cette figure était de 165 yw, c’est-di-dire un dixieme et demi de milli-
métre—0°15 mm,

Dans la fig. 1, B, qui représente un sphincter coupé en travers, la lumiere
était encore plus réduite et ne mesurait que 47 uw, soit par conséquent pas
méme un demi-dixiéme de millimétre—0047 mm.

Il résulte de ces observations et d’autres faites sur des piéces macro-
scopiques durcies au formol, que les sphincters s’observent dans deux points
différents, mais consécutifs de l’arbre bronchique :

1° Sur des troncs qui mesurent un peu moins d’un millimétre de diamétre
extérieur.

2° Sur les rameaux qui naissent de ces trones et s’écartent 4 angle droit
en formant des conduits plus fins et dont le diamétre descend jusqu’a un
peu moins d’un demi-millimétre.

Tl est clair que ces formations musculaires sont parfaitement cag

* Max Weber, Die Stiugetiere, Jena, 1904, p. 227,

Sur la Structure du Poumon du Dauphin (Delphinus Delphis) 289

de fermer complétement les bronches, surtout au niveau des points de
Yarbre bronchique ot va se faire la division des bronches indiquée plus
haut. Dans ces points les sphincters se multiplient, et par la distribution
méme des ramifications bronchiques qui s’effectue 4 angle droit, il arrive
fréquemment que les sphincters de deux bronches voisines s’entrecroisent
obliquement et forment ainsi des nceuds musculaires d’une efficacité encore
plus marquée (fig. 1, A, n.sph.).

Il est fort probable que ces sphincters aussitét Vinspiration achevée,
maintiennent l’air enfermé dans les terminaisons bronchiques au dela
desquelles ils se trouvent, et qu’ils se relichent brusquement au moment de
Yexpiration. Cette disposition est sans doute en rapport avec les plongées
de l’animal.

Dans les bronches ot ils commencent 4 se montrer les sphincters sont
réguliérement espacés et isolent entre eux des chambres mesurant en
moyenne 419 w de longueur et 432 « de largeur. Dans les chambres
représentées, fig. 1, A, celle qui présentait la plus petite longueur mesurait
187 w et la plus longue présentait 718 ~; comme largeurs limites nous
avons obtenu pour la chambre la plus étroite 156 w et la plus large a donné
ala mensuration le chiffre de 500 w, c’est-A-dire 0°5 mm., en comptant toujours
ces chiffres du cété intérieur. Dans les bronches plus petites les sphincters
sont encore plus serrés.

Les chambres bronchiques limitées pas les sphincters possédent un
réseau capillaire sanguin 4 mailles arrondies tout a fait analogue a celui des
alvéoles pulmonaires et qui se déverse dans la veine pulmonaire, comme
jai pu m’en convaincre sur des foetus de Dauphin au niveau de la portion
amincie du poumon, ot existait une véritable injection naturelle trés facile
& observer dans les préparations éclaircies.

Bien que, aprés la mort, les sphincters soient toujours ouverts, ils
opposent cependant une certaine difficulté & la pénétration des injections
bronchiques.

Javais été surpris de n’obtenir avec la masse métallique de Wood,
quune pénétration assez imparfaite, la masse ne depassant jamais les
ramifications mesurant moins d'un demi-millimétre, mais j’ai pu voir par la
suite qu’a l’extrémité de ces ramifications l’empreinte annulaire des sphincters
se voyait déja et que cétaient évidemment eux qui avaient arrété la pro-
gression de la masse. De plus les étranglements produits par les sphincters
rendent trés cassantes les extrémités des rameaux bronchiques injectés qui
sont pour la plupart perdues lorsqu’on nettoie la piéce aprés corrosion.

Dans tout le territoire bronchique ot se rencontrent les sphincters, ces
derniers représentent seuls la musculature bronchique, il n’existe pas de
fibres musculaires au dehors d’eux. Les sphincters s’observent déja chez

290 Dr José Martins Barbosa

des fcetus d’assez grande taille. La fig. 2 en représente une série, dans
un poumon de foetus de 55 em. Les anneaux musculaires sont déja bien
développés et ferment presque completement la lumiére bronchique. |

Les piéces cartilagineuses sont déja aussi visibles, les conduits alvéolaires
sont bien développés. On voit en divers endroits la lumiére bronchique
presque entiérement effacée par la forte saillie des sphincters, et 4 ce niveau
l’épithélium bronchique est fortement aminci comme on le voit particuliére-
ment vers l’extrémité distale de la bronche (fig. 2, br.e.d.). Au voisinage de

Fic. 2.—Coupe sagittale du poumon d’un feetus de Dauphin de 0°55 centimétre.

br.e.d., bronche extrémité distale; br.e.p., bronche extrémité proximale; c.a/., conduits alvéolaires ;
cart., cartilage ; ch.br., chambres bronchiques; 7.b7., rameaux bronchiques; sph., sphincter; sph.t.,
sphincters coupés tangentiellement.

cette extrémité un rameau bronchique (fig. 2, 7.br.) est implanté 4 angle
droit sur la bronche et il est muni d’un sphincter au voisinage du point ou
il s'élargit, brusquement passant alors dans un conduit alvéolaire.

II. MopE DE RAMIFICATION DES BRONCHES TERMINALES.

Les bronches terminales font suite 4 des bronches de petit calibre qui —
mesurent environ 0°25 mm.—deux-dixiémes et demi de millimétre—et qui
préesentent des sphincters. Elles sont plus volumineuses et leur calibre va

a
S
X

Th ye

Sy

&_....------
Ftp en” :
» -

Fic. 3.—Coupe paralléle & la surface dans la partie amincie du poumon (extrémité
terminale de la bronche représentée fig. 1).
ximale; br.e.t., bronche extrémité terminale; c.a/., conduits alvéolaires ;

br.e.p., bronche extrémité
q ; lbr., lumiére bronchique ; r.al., réseau capillaire des alvéoles dans les parties de

,

ca
ceux-ci que sont vus de face.

292 Sur la Structure du Poumon du Dauphin (Delphinus Delphis)

méme reguliérement croissant jusqu’é leur extrémité comme on le voit bien
dans la fig. 3, dont la bronche mesure 3 mm. de longueur et dans son ex-
trémité proximale nous montre une largeur de 250 yw, pendant que dans le
milieu elle mesure 4 peu pres 312 w et & son extrémité distale elle présente
la largeur assez considérable de 470 y.

La paroi de la bronche est formée par la muqueuse renforcée ga et la
par des plaques cartilagineuses assez écartées les unes des autres. Ces
plaques se poursuivent sur toute l’étendue de la bronche et on trouve
toujours un petit nodule cartilagineux a l’extrémité de celle-ci, entre les
derniers conduits alvéolaires qui en naissent et qui continuent a peu pres sa
direction.

Sur tout le pourtour de la bronche ainsi constituée s’ouvrent des con-
duits alvéolaires qui se ramifient plus ou moins. La plupart d’entre eux
sont implantés a angle droit sur la bronche dans laquelle ils s‘ouvrent
largement.! Seuls derniers conduits alvéolaires ont une direction oblique
et prolongent pour ainsi dire la bronche sur une certaine longueur.

Ainsi chaque bronche terminale occupe l’axe d’un manchon de cavités
respiratoires greffées sur elle, et cet axe est pourvu sur toute sa longueur de
nodules cartilagineux plus ou moins développés. II n’y a point de bronches
sans cartilage, et d’autre part la distribution réguliére des conduits alvéo-
laires tout autour de la bronche axiale constitue un mode de ramification
tout a fait distinct de celui qui s’observe chez Homme et chez beaucoup
d'autres Mammiferes et que M. le Prof. Laguesse a caracterisé par le mot
tres just de ramifications en choux-fleur?

Dans toute l’étendue de la bronche terminale, on n’observe point des
fibres musculaires lisses, et celles-ci paraissent aussi manquer dans les con-
duits alvéolaires.

Malgré tout l’attention que j’ai apporté a les rechercher, je n’ai point
trouvé non plus d’anneaux musculaires lisses autour de louverture des
conduit alvéolaires dans la bronche axiale, de sorte que les sphincters
décrits par Rindfleisch pour certains animaux manquent absolument chez
le Dauphin.

Dans toutes les coupes les réseaux capillaires gorgés de globules rouges,
a cause de l'état: asphyxique auquel a succombé l’animal, se voient admir-
ablement et ils ont été représentés dans la fig. 3 partout ou la paroi
alvéolaire se voyait de face.

1 Les mensurations que j’ai obtenu pour Vouverture de ces conduits alvéolaires qui
sont représentés fig. 3 sont: a droite 312 p et 218 p, et & gauche 312 p.

2 Laguesse, E., “Trois legons sur la structure du poumon,” Extrait de ’ Echo Médical

du Nord, 1901, p. 36.

a ia tn oe

AN UNUSUAL PERITONEAL SAC. By F. A. Hepwortu, M.A.,
M.B(Camb.), F.R.C.S., Demonstrator in Anatomy.

(From the Anatomical Department, Sheffield University.)

THE subject was an adult male; death had apparently resulted from
melanotic sarcoma, and had no relation to the abnormal abdominal con-
dition here described.

On opening the abdomen, attention was at once drawn to a smooth cyst
occupying a large part of the left side of the cavity. The stomach and
transverse colon were normally situated and contracted; the shrunken
great omentum lay obliquely across the upper abdomen, leaving the con-
tents of the lower part exposed to view. Below the right (lower) end of
the curled-up omentum was the cecum, rather distended and turned
upwards from the iliac fossa with its fundus pointing towards the middle
of the abdomen. Below the left part of the omentum was placed the cyst,
and the only portion of the small intestine visible on first examination was
the terminal two feet of ileum which occupied the hypogastric area, below
the czecum and the cyst (fig. 1).

By drawing the cecum to the right and turning the coil of ileum up-
wards, the appendix and ileo-cxcal junction were brought into view. To
the left of them, almost in the middle line of the body, there was an opening
through which the ileam emerged from what at first sight appeared to be
a retro-peritoneal fossa. But only.an emerging coil was present ; there was
no entering loop as in a retro-peritoneal hernia (fig. 2).

The ascending colon lay far back in the right lumbar region and could
not be seen, but the descending colon was just visible on the outer side of
the cyst.

The cyst itself was next examined and found to be thin-walled, mem-
branous, and“not adherent to colon, omentum, or other organs. It was
obviously peritoneal, showing no signs of being pathological in origin.
When opened it was seen to be closely filled by coils of small intestine, and
on drawing these out the extent of the cavity was revealed. It was a
smooth-walled space, extending from the level of the 9th rib in the
anterior axillary line down to the posterior part of the iliac crest ; medially
it reached as far as the middle line, and laterally almost to the abdominal
wall. The whole space was lined by peritoneum which was in direct con-

294. Dr F. A. Hepworth

tact behind with the anterior surface of the left kidney, the tail of the
pancreas, the ascending portion of the duodenum and duodeno-jejunal
junction, and lower down with the aorta and left lumbar muscles (fig. 3).
Traced to the right, the peritoneal lining was found to pass from the
duodenum on to the posterior, or inferior, aspect of the mesentery, follow-
ing the course of the normal parietal peritoneum ; but to the left it reached

-

Omentum.

Cecum (lying in
its abnormal
position).

Fic. 1.

: 3}
well into the flank, turned forwards behind the descending colon, and then

passing inwards to form the anterior wall of the cavity, it joined the layer

of peritoneum which covered the front of the descending colon. The —

anterior cyst-wall was therefore a double sheet of peritoneum, and the two

layers could be separated with comparative ease as far back as their —
reflection from the abdominal wall in the neighbourhood of the descending
colon. The division could be followed upwards also as far as the transverse —

mesocolon, to the under surface of which the cyst-wall was attached, but

«

‘An Unusual Peritoneal Sac 295

__ down over the iliac fossa to become the sigmoid mesocolon, while the deep
layer was reflected on to the abdominal wall at the back of the cavity.

_ Separation of the two layers again became difficult when the anterior

Omentum.

Abnormal cyst.

Mesentery of ——~
appendix. ——— Coil of ileum
emerging
from sac.

eee See UES

“Sigmoid.

Fie. 2.

_ wall was followed towards the middle line. Enclosing, as it did, almost
all the small intestine, the sac also included all the corresponding part of
_ the convoluted edge of the mesentery. But the front of the sac was firmly
- bound down to the anterior or upper surface of the mesentery not far from
_ its root, along a line of attachment rather more vertical than that of the
- root of the mesentery. The line of attachment was marked by considerable
thickening, and it was impossible to identify two separate layers, or to say
whether they were continuous with the peritoneum of the mesentery or

296 Dr F. A. Hepworth

secondarily adherent to it. The band of thickened peritoneum was con-
tinued downwards as the fold which formed the anterior (left) margin of
the outlet from the sac, and could be traced downwards and to the left
over the sacral prominence to the iliac fossa, where, as already mentioned, —
the anterior wall of the cyst appeared continuous with the sigmoid meso-
colon. Followed upwards, this attachment of the cyst-wall passed from the

Peritoneum forming lower a of
rmeasntory 12 gall aeeeleaen..
Fic, 3.—The cyst opened and its contents turned out.
mesentery to the posterior abdominal wall just mesial to the duodeno-
jejunal junction, and above that became fused with the transverse meso-
colon. ais:

The contents of this abnormal sac were small intestine and mesentery,
from the duodeno-jejunal junction to within two feet of the ileo-czcal
valve. The bowel made its exit from the cavity by passing through a

tunnel of peritoneum formed by the attachment of the anterior wall of 5

An Unusual Peritoneal Sac 297

the sac tothe anterior (upper) aspect of the mesentery, and by the thickened
free edge of this wall as it left the mesentery to gain the posterior abdominal
parietes in the neighbourhood of the last lumbar vertebra. The tunnel
was directed downwards and a little to the right, and lay in front of the
prominence formed by the spinal column, aorta, and inferior vena cava.
The explanation of this unusual abnormality is difficult, but the peri-
toneal arrangements seem to suggest that a fold arising from the mesocolon
—from near the middle of the transverse to the middle of the sigmoid—
had become adherent by its margin to the right of the mesentery of the
small intestine, and had thus enclosed the whole of the jejunum and greater
part of the ileum (fig. 5); but the remainder of the peritoneal surface

Small intes-
tine within
Hormat abnormal
Peritoneal bani
Descending
colon.
Duodenum.
L. kidney.
Fic. 4.—Diagram to show Fic. 5.—Diagram of peritoneal arrangement at level
relation of cyst - wall immediately below duodeno-jejunal junction..
attachments to small Wall of abnormal sac shown by double red line ;
intestine, mesentery, normal peritoneum by black line.
and colon.

showed nothing suggesting disease, and the cyst-wall had the appearance
of normal peritoneum and not that of an inflammatory product.

I am led to conclude that the presence of the fold was due to an error
in the process of development. It is significant that the contents of the
eyst comprised that section of bowel which forms the proximal part of the
umbilical loop during the second and third months of fcetal life; and that
the abnormal peritoneal fold was closely connected at its margins with a
little less than the left half of the transverse mesocolon and the descending
and sigmoid mesocolon—that part, in fact, which is always intra-abdominal,
and which occupies a median position until the withdrawal of the umbilical
loop into the abdomen at about the tenth week.

In an interesting paper by Professor J. E. Frazer and Dr R. H. Robbins,
in the Jowrnal of Anatomy and Physiology, October 1915, “On the

298 . An Unusual Peritoneal Sac

Factors concerned in causing Rotation of the Intestine in Man,” it is described
how during the third month of development the bowel returns from the
umbilical sac to the abdominal cavity, the proximal part of the umbilical
loop returning before the distal, and filling up first the space to the right
of the median mesocolon below the liver; as the bulk of returning coils
increases, the median mesocolon is pressed to the left and carries the colon
over until it rests upon the posterior abdominal wall, the umbilical loop
then passing to the left also, and filling the space below the stomach and
omental bursa (figs. 12, 18, and 15 in Frazer and Robbins’ article).

It is conceivable that an abnormality may occur at this stage, and that
as a result perhaps of an unusually long median mesocolon, the accumulating
mass of returned intestine may simply cause a lateral bulging of mesocolon
towards the left, without at first displacing the colon itself. Supposing

Umbilical
Loop.

Fic. 6.—To show suggested mode of development of abnormal peritoneal sac.

this to occur, the right side of the mesocolon would form a concavity
occupied by coils of intestine from the proximal part of the umbilical loop ;
and increasing pressure would tend to cause adhesion between the margin of
_ this surface of mesocolon and the root of the mesentery (fig. 6, A, B, and C).

The later movement of the colon to the left would then cause a drawing
out of the adherent surface, with the result that a new fold of peritoneum
would pass from the mesocolon to the root of the mesentery, in front of the
intestine from the duodeno-jejunal junction to the apex of the umbilical
loop.

This theory does not explain the peculiar curled-up condition of the
great omentum found in this subject, but a possible suggestion is that the
omentum normally intervenes as a bursa between bowel and abdominal
wall; and that in the presence of an abnormal peritoneal protection such ~
as was formed by the sac described above, there was no need for an omental
bursa, and the stimulus to its downward growth was lacking. .

CONGENITAL DEFICIENCY OF THE PERICARDIUM.
By Martin R. Cuase, M.D.

(From the Anatomical Laboratory of the Northwestern University Medical School.' )

A CONSIDERABLE number of cases of congenital deficiency of the pericardium
have been recorded. Faber in 1878 collected ten eases. Ebstein, 1910,
found thirty-two cases reported. Perna, 1910, and Plaut, 1913, have recently
summarised the literature on the subject, and reported additional cases.
The reader is referred to their papers for a complete consideration of the
literature.

It is the purpose of this paper to present a short description of a case
found in this laboratory. At the time the body came under our observa-
tion, all parts except the chest had been dissected, thus losing the identity
of the subject.

_ The chest was that of a fairly well-developed adult male presenting a

marked kypho-scoliosis. On opening the right pleural cavity it was noted
that there were extensive adhesions between visceral and parietal pleura,
and evidence of tuberculous involvement of the right lung. The mediastinal
partition seemed normal.

On opening the left pleural cavity, however, the left lung and the heart
came clearly into view, lying in a common serous cavity. Examination
shows that this is due to a large defect of the left half of the parietal
pericardium. The visceral pericardium is normal. Around the base of the
heart is a more or less sickle-shaped fold with a free border, which almost
encircles and partially encloses the base of the heart. This fold begins on
the superior aspect of the root of the left lung as a reduplication of the
serous membrane about 1°5 em. wide, having its attachment along a line
passing horizontally forward, across the ascending aorta to the mediastinal
partition, thence downward as a reduplication of the mediastinal pleura to
reach the diaphragm just to the left of the sternal attachment of the 6th left
costal cartilage. From this point a continuation extends upwards over the
dome of the diaphragm, passing to the left of the inferior vena cava, to
blend with the left pulmonary ligament.

Taken as a whole, the left portion of the pericardium may be considered
as a reduplication of the serous lining of the common pleuro-pericardial

1 Contribution No, 39.

300 Dr Martin R. Chase

cavity, encircling the base of the heart from the upper aspect of the root of
the lung to the pulmonary ligament on the inferior aspect of the pulmonary

Root of lung.

Phrenic nerve.

Phrenic nerve, —-—

Rud. fold. ones

Drawing of heart from in front and to the right, showing cut section of pulmonary root,
and rudimentary fold of pericardium with phrenic nerve. Owing to the deformity
of the spinal column the aorta appears to bend sharply to the right.
root. It contains on the right side where it is attached to the mediastinal
pleura, and at its anterior attachment to the diaphragm, thickenings of

—

Congenital Deficiency of the Pericardium 301

fatty tissue whichin places assume the shape of tags of fat covered with
serosa.

The fold varies in width from 2°5 cm. along the mediastinum to 3°5 em.
where it is attached to the diaphragm. To the left and in front the visceral
pericardium is directly in contact with the visceral pleura on the mediastinal -
surface of the left lung. More anteriorly and in the cardiac notch of the
lung it lies against parietal costal pleura. Below, the heart is in contact
with the diaphragmatic pleura.

The heart itself is of normal size and appearance. It is covered with
serous pericardium which continues over the roots of the great vessels in a
normal manner. The transverse and oblique sinuses of the pericardium
are present. There are present no adhesions of the visceral pericardium
with parietal pleura or lung, as was found in many of the cases reported,
the serosa of the common pleuro-pericardial cavity being smooth and free
in all parts. The heart shows no congenital defects. The ductus arteriosus
and the foramen ovale are closed.

PHRENIC NERVE.

The phrenic nerve enters the thorax behind the left innominate vein,
courses downward to the left of the innominate vein, crosses the arch of
the aorta anterior and a little to the left of the origin of the left common
carotid artery, and enters the fold of pericardium at its attachment just
below the arch of the aorta. It then turns to the right along the free
border of the fold, which it follows to the diaphragm. In some of the
cases reported no rudiment of pericardium was found. In others rudiments
were present ranging from tag-like pads about the base of the heart to
crescentic folds completely enclosing a part of the heart. In a case reported
by Keith, in a foettis presenting many other congenital anomalies, a small
aperture was seen in the left side of the pericardium through which the
left auricular appendage protruded. In Powell’s case there was an opening
only one-eighth of an inch in diameter in the left side of the pericardium,
which had smooth edges and showed no signs of erosion. In his subject
the condition of pneumo-pyothorax was present, and the pericardial sac
contained air and pus.

The course of the phrenic nerve was, in all cases except Perna’s, to the
right of the deficiency. In cases of well-marked folds it ran in the fold
near the free border. Where the fold was small or absent it ran in the
mediastinal partition, between the two pleural sacs. In the cases of
Versé and Picchi (quoted from Plaut) it ran in a fold behind the sternum.
In Perna’s case the phrenic took a course across the root of the lung

VOL. L. (THIRD SER. VOL. XI.)—JULY 19°6. 20

302 Congenital Deticiency of the Pericardium

posterior to the pulmonary artery to reach the posterior part of the
diaphragm.

So far as known, the condition has no clinical significance and has never
been diagnosed ante-mortem.

Keith thinks the explanation of the condition is that the lung-bud grows
through the pleuro-pericardial foramen, expanding that opening, and pre-
venting its normal closure.

Perna suggests that early establishment of the anastomosis between the
left and right anterior cardinal veins results in early atrophy of the left
duct of Cuvier (common cardinal vein). Inasmuch as the pleuro-pericardial —
membrane, which normally completes the division of the pericardial cavity
from the pleural cavity, is carried by the duct of Cuvier, early atrophy of
the left vein would result in incomplete development of the left membrane
and persistence and enlargement of the left pleuro-pericardial foramen.
The fact that all known cases of congenital deficiency of the pericardium
occurred on the left side would support this view.

M°Garry discusses the embryological significance of the malformation,
and expresses the opinion that the occurrence of a patent pericardium
is one aspect of a general condition. He explains these cases “ by supposing
that in the early development of the embryo, some slight injury occurred
to the general ccelom, which resulted in a lack of development of the
pleuro-pericardial membrane.”

LITERATURE.

Faper, Virchow’s Archiv, Bd. Ixxiv.

Epstein, Miinchen. med. Wehnschr., 1910, Bd. x. 8. 522.

Perna, Anat. Anz., Jena, 1910, Bd. xxxv. 8. 522.

Puaut, Frankfurt Ztschr. f. Path., 1913, Bd. xii. 8. 141.

Kerru, Journ. Anat. and Physiol., London, 1907, vol. xli. (3rd Ser. vol. ii.) 6.
Powe, Trans. Path. Soc, London, vol. xx. p. 99.

Verst, Miinchen. med. Wehnschr., 1909, Nr. 57, 8. 2664.

M°Garry, Anatomical Record, 1914, vol. viii. p. 43.

—

ih eal alli

THE RELATION OF THE AMPHIBIAN PARASPHENOIDS.
By Dr H. Leicuton KESTEVEN.

THESIS.
1. The greater part of parasphenoid of the Amphibia is represented in
Superamphibia by the paired pterygoids.
2. The amphibian pterygoid appears elsewhere only in some Reptiles, in
which it has been named Ectopterygoid.
3. The reptilian parasphenoid represents the anterior portion only of
the amphibian parasphenoid.

Ir it be proven that the amphibian parasphenoid is truly represented by
the reptilian pterygoids, then it follows that the reptilian parasphenoid can
represent, at most, only part of the amphibian parasphenoid. Our know-
ledge of cranio-ontogeny is as yet fragmentary, and comparisons have been
largely based on considerations of types rather than groups, and this is
particularly, and necessarily, so when embryological evidence is adduced,
since the material is scanty. Thus as a result of the work of many in-

_vestigators, more especially of Parker and Gaupp, Lacerta has come to

be accepted as the type or standard of reptilian cranium. In this the
parasphenoid, at one stage of development, presents such marked similarity
to the amphibian parasphenoid that one hesitates to suggest that it is
incorrectly named. Without challenging the homology of these bones,
Broom has advanced convincing reasons for regarding’ them as homologous
with the mammalian vomer. It is significant that, with the exception
perhaps of some Cetaceans only, in all the Superamphibia the vomer is.
limited posteriorly in the neighbourhood of the pituitary body, if indeed it
extends so far back. Remembering the important muscular attachments
to the amphibian parasphenoid at its hinder end, and that there are none to
the vomer (or parasphenoid) of higher forms, one inquires, Whither have
these attachments wandered? The answer is, In part to the pterygoid both
in the Reptilia and Mammalia.

Do these pterygoids represent the posterior portion of the amphibian
parasphenoid ?

A priori, a bone so extensively developed as the parasphenoid in the
Amphibia, and serving such important functions, should not dwindle al-
most to disappearing point in the process of evolution. As the matter now

304. Dr H. Leighton Kesteven

stands, such is tacitly accepted as having taken place, for the reptilian vomer
(parasphenoid of authors) with few exceptions is so insignificant a bone
that it cannot be demonstrated in the dried skull, and we have learned to
believe that this remnant represents the amphibian parasphenoid.

A more acceptable interpretation of the bones on the basis cranii is that
offered above, namely, the pterygoids of the Reptilia represent the major
portion of the amphibian parasphenoid,

If this be so, then the reptilian pterygoids are primitively median in
position and should articulate one with the other along the mid-line. Such
a primitive condition is realised in the triassic Votosawrus, in Chelonia and
Crocodilia. In all these we find the paired plory gokds presenting the follow-
ing eee relationships and characters :—

1. They are membrane bones.

2, Meeting along the mid-line, they are placed immediately beneath the

basis cranii extending from the occipital region behind to the

olfactory region in front.
. They underlie, without intervening structures, the basi-sphenoid and
rostrum basi-sphenoidei (i.e. the erstwhile cartilaginous basis cranii).

4. Posteriorly, by lateral expansions, they are related to the wet acs

and underlie the otic capsules.

5. Anteriorly they articulate with the palatine bones on either side of

the mid-line, and are related to the posterior nares.

6. Posteriorly they give attachment to muscles of mastication.

Effecting only such changes as are necessitated by the fact that the
amphibian parasphenoid is unpaired, the above six statements constitute
also a description of this bone.

In the presence of such complete resemblance one is forced to assume a
truly remarkable analogous replacement of amphibian parasphenoid by
reptilian pterygoids, or admit that the latter are homologous with the
former. That the amphibian parasphenoid should be thus homologous with
three bones on the base of the reptilian skull involves only the assumption
that in the more highly specialised skull the bone develops from three
centres of ossification which fail to fuse.

Comparing the ectopterygoid of the crocodile with the pterygoid of
Rana it will be found that the following hold true in both cases :—

1. The bones are on the postero-lateral border of the infra-orbital region.

2. They are triradiate.

3. The anterior ramus is related to the maxilla, and to the palatine bone

laterally with respect to the orbit.

4. The postero-lateral ramus is related to the quadrate or quadrato-jugal

(z.e. to the maxillary arch posteriorly).

oo

—--.)

The Relation of the Amphibian Parasphenoids 305

~~ 5. The postero-medial ramus is related to the parasphenoid (pterygoid
of authors, in the Reptiles).

6. Neither of these ever present the median relation to the palatines
and choanz so constantly seen in the reptilian paired parasphenoids
(pterygoids).

7. They form a bony bar over which the muscles of mastication work,
and which separates the temporal fossa from the orbit.

Once again, if these bones are not homologous then there has been a

truly remarkable analogous replacement.

The reptilian pterygoid, like the amphibian parasphenoid, is a mem-
brane bone applied medially to the base of the skull, whilst the amphibian
pterygoid and reptilian ectopterygoid are essentially components of the
suspensorium.

If the reptilian pterygoid is the same bone as the amphibian pterygoid,
then in assuming its reptilian situation it has as it were melted from before
backward on the outer aspect of the orbital region, and then grown forward
again along the base of the skull medial to the orbital region. In support
of such a migration there is no shred of embryological evidence, and
intermediate stages in the paleontological record are hard to find. Among
recent forms Cryptobranchus japonicus may be cited as one such, but it is
a long way from the condition presented by the pterygoids in the Chelonide,
Crocodilia, and Sawropterygia.

It may be contended that the pterygoid in these three groups of skulls
is atypical and therefore misleading. Such an argument, however, fails if
it be granted as possible that they are evolved from a median parasphenoid,
for then they present the primitive type condition. In the absence of
such a postulate the examination of a series of other reptilian skulls reveals
the fact that these pterygoids differ from those of other members of the
class mostly in their size, and not at all in relation to other bones or skull
regions—in short, there can be no doubt that it is the same bone which has
been termed “ pterygoid ” throughout the whole reptilian series.

It has been contended that in coming to oceupy. the position it does,
the pterygoid in Chelone has undergone medial extension; there is
equal justification for supposing that the more laterally placed pterygoids
of, e.g., Lacertilia have retreated from the median line.

If the reptilian pterygoid is primitively a paired basi-cranial covering
bone (parasphenoid), then the process of its conversion into a cranio-visceral
skeletal element related to the pharynx and muscles of mastication,
perhaps determined by those relationships, and its separation from the
basis cranii, may be recognised in its various stages within the class.
Trionyx presents the first stage, the pterygoids being separated by the

306 Dr H. Leighton Kesteven

basi-sphenoid ; after viewing Pelochelys and Sphenodon one is more pre-
pared for the condition in the monitors, blue-tongues, and. other lizards.
In all these cases the relationships to bones and skull areas, emphasised
earlier, are maintained.

Particularly interesting are the constant articulation with the basi-
sphenoid, just anterior to the pituitary region (basi-pterygoid process), and
the relation to the choanz and Eustachian apertures, inasmuch as these
relationships persist in the Aves and Mammalia.

Gaupp is of the opinion that the reptilian vomer (parasphenoid of
authors) is homologously replaced by the paired pterygoids of the Mammalia.
One of his objections to recognising as homologous the similarly named
bones (pterygoids) in the Reptiles and Mammals is the lateral position of
the bones in the Reptiles. In this he is apparently obsessed by the
situation of the pterygoids in Lacertilia. . In the Chelonians, Crocodilians,
and Sauropterygians, as has already been emphasised, these bones are
situate immediately beneath the neural cranium. He believes that the
median extension of the pterygoids in Chelonia has been brought about by
reduction in the basi-pterygoid process, whereas it has just been shown that
it is more probably primitive, and therefore the basi-pterygoid process is a
later development.

The condition in the Mammals is, in the view here presented, a per-
petuation of the anterior segment of the lacertilian condition, namely, that
portion extending from the basi-pterygoid process to the posterior naso-
palatine border, and the basi-pterygoid process could have (as has been
suggested) expanded into the ala temporalis, but dorsal and posterior
to it.

Whilst thus differing from him in this instance, I would, however,
quote Gaupp’s authority in support of my contention that a median basi-
cranial bone in one phylum may in another be homologously replaced by
paired bones.

It may be well at this stage to emphasise the fact that the original
application of the name “ pterygoid ” to the bones so named in the Amphibia
and Reptilia did not result from embryological study, nor has the homology
involved ever been confirmed by embryological evidence; in no case does
the reptilian pterygoid ever first appear postero-lateral to the infra-orbital
region ; in all cases hitherto investigated it first appears on either side of
the basis cranii, medial to that region.

The reptilian octo-pterygoid, chosen above for comparison with the
amphibian pterygoid, is admittedly better developed than is usual in most |
reptiles ; on the other hand, the amphibian type chosen is the best developed
in that class. Though this bone presents a fairly wide range of variation

me ee eae a —

The Relation of the Amphibian Parasphenoids 307

in both classes, there can be no doubt that it is always the same bone that
is termed ecto-pterygoid in the Reptilia, and in the Amphibia, pterygoid.
That the variations do not affect the arguments set forth above, is shown in

the following table :—

EcTo-PTERYGOID AND PTERYGOID
(AMPHIBIAN).

Always lateral or postero-lateral to the
orbit.

Never medial to the orbit.

Articulation with the lateral portion of
the posterior margin of the palatine bone.

Anteriorly se from its fellow of the
opposite side by the whole width of the
postnarial region.

The two bones are never in juxtaposition
medially in front.

: In no case do these bones articulate with

the “ones ere

Postero-medially they are always in juxta-
position to the membrane bone covering
the base of the skull.

PTERYGOID (REPTILIAN).

Never lateral to the orbit.

Always medial to the orbit.

Articulation with the medial portion of
posterior margin of the palatine bone.

Never so separated.

The two bones are always in juxtaposition
medially in front.

These bones always articulate with the
basi-sphenoid. ‘

Postero-medially these bones constitute the
membrane bone covering the base of the

skull, or else there is no such bone de-

veloped,

This table is largely a repetition of previous discussions, but placing
in contrast the relationships of reptilian and amphibian pterygoids, it
emphasises the difficulties in the way of the homology involved in the
old nomenclature. It is hardly believable that these bones, whose most
important relations to other bones and regions of the skull are capable
of correct description, thus, in alternate negative and affirmative, are
really homologous. On the other hand, it is equally difficult to believe
that the two bones described together in the left-hand column are not
homologous. :

It is therefore to be concluded that:

1. The reptilian pterygoids are wrongly named, they should be termed
paired parasphenoids, and they represent the major portion of
the amphibian parasphenoid, with which they are completely
homologous. |

2. The reptilian ecto-pterygoids should be termed pterygoids, and they
are completely homologous with the amphibian pterygoids,

THREE CASES OF REAPPEARANCE OF OVARIAN PERITONEAL
SACCULATION IN THE HUMAN FEMALE. By Epwarp
ReEyNOLps, M.D.

SINcE we have come to realise that the embryological record furnishes
merely a sketch of the main lines of descent, and that the developmental
peculiarities observed in individuals not only have the same significance
of reversion to ancestral traits, but are for that reason capable of filling in
the details of descent, the submission to record of every such observation
has become of greater importance.

The relation of the ovary to its endometrium is not only extremely
variable throughout the Vertebrates, but is interesting in the fact that the
occurrence of sacculation is irregular in its distribution, frequently appearing
in individual species among genera which are otherwise free from it. I
have, however, been able to find no previous record of the occurrence of
this relation among individuals in a species which is normally free from
it. The human female is normally peculiar among the Vertebrates in
possessing an almost, if not quite, complete absence of any trace of
peritoneal sacculation of the ovary, hence the study of three individuals
in which this anomaly appeared seems worthy of record.

The anatomical relations of the ovary to the adjacent peritoneum vary
widely as between different species of the same family in almost all genera
throughout the mammalian kingdom. The ovary is always attached by
one border only to the inner or medial surface of the mesometrium or
broad ligament. In the simplest form of its peritoneal relations it hangs
dependent from this attachment with its outer surface in simple contact
with the inner surface of the mesometrium, more commonly the surface
of the broad ligament which is in contact with the ovary is recessed into
a shallow depression against which the ovary lies. From this simplest
form of the relations all gradations are met with up to those in which
this depression has been not only deepened into a pouch, but its orifice
contracted until the ovary and the fimbriated extremity of the Fallopian
tube lie in an accessory cavity of the peritoneum which is entirely closed
from the general cavity. These modifications of the relations of the ovary
to the body cavity are, moreover, foreshadowed by similar arrangements
which exist even among the Invertebrates. The literature on the subject
is scanty. Reference to it, however, occurs with considerable frequency in

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Three Cases of Reappearance of Ovarian Peritoneal Sacculation 309

Owen’s Anatomy of Vertebrates, in which, moreover, there is frequently |
reference to monographs describing individual species. The only detailed
article upon the subject which I have been able to find, after somewhat
extensive search, is one by Professor Arthur Robinson.' This article gives
excellent figures of several typical modifications, and since excellent
examples of most of them occur in the common domestic animals, personal
verification of these figures is comparatively easy.

I have not been able to find any reference to a species in which there
is no depression of that portion of the broad ligament which is in contact
with the ovary, although it is stated that this form is known. The human
female, however, offers an excellent example of almost this condition, the
accepted description being that the ovary lies in contact with a shallow
depression in the surface of the broad ligament, while my own observations
have made me somewhat doubtful as to whether this depression is habit-
ually perceptible ; but this question will be referred to later. An excellent
example of an early stage of the formation of the pouch is to be found in
the common cat; an intermediate stage of development of the ovarian sac
exists in the porcupine; and the most complete form known in the common
mouse, in which the peritoneal covering of the edges of the orifice have
become fused with the peritoneal covering of the Fallopian tube, so that.
the ovary and fimbriated extremity are entirely shut off from the general
cavity.

The distribution of the ovarian sacculus through the mammalian
kingdom is roughly as follows. Each of the different families shows for
the most part a general tendency either to more or less complete saccula-
tion of the ovary or to its absence, but the amount of sacculation varies
very greatly among the different species within the genus.

In the Monotremata and Marsupials the ovary lies in contact with a
shallow peritoneal groove. In the Insectivora there is as a rule a nearly
complete sacculus. Among the majority of the higher genera any approach
to complete sacculation is exceptional, but it is prevalent in several widely
separated families.

In the Perissodactyla the anatomy varies between deep but widely open
saceules and the condition found in the mare, in which the ovary lies
enclosed and concealed in its special peritoneal cavity.

Among the horned Ruminants the existence of a sac is the rule, but the
degree of enclosure varies within wide limits.

The ovaries of the Carnivora are mostly contained within saccules, that
of the white bear being so nearly complete that only a minute communica-

tion with the general eavity is left.

1 Journ. Anat, and Physiol., London, 1886-7, vol, xxi. p. 169.

310 Dr Edward Reynolds

The Rodentia are peculiar in that they exhibit every variety between
a mere shallow depression in the peritoneum of the broad ligament and the
condition found in the rat and mouse, in which the ovarian sac is absolutely
shut up in the broad ligament and its one opening is its communication
with the cavity of the uterus through the Fallopian tube. .

Among the Primates a rudiment of the sacculus is found in Perodicticus,
Lichanotis, Otolicnus, Tarsius, and Stenops.

I have been unable to find any reference to individual variation in the
amount of sacculation within the limits of any species, though such may
very probably exist.

When an ovarian sacculus exists it always lies within the cavity of the
mesometrium. | |

In the Monotremes and Marsupials the uterus is double, and in one of
my human cases the anomaly of double uterus was present. In the
majority of the Mammals it is’ bicornuate, consisting of a body and two
diverging cornua. In the Primates it is single throughout, the Fallopian
tubes originating from the angles of the single body.

In the human female the mesometrium or broad ligament has been
developed under the requirements of the erect posture into a highly
specialised supporting structure containing well-developed so-called liga-
ments (most of which are non-existent in the quadrupeds), by which
process it is altered from the very simple and almost linear form which
it possesses in most Mammalia to an irregular, quadrilateral, and very
complicated shape. These great changes make a comparison of the human
broad ligament with that of the quadrupeds difficult and at times mis-
leading. In the human female the large and long Fallopian tube is usually
described as lying in the free edge of the broad ligament. It may more
properly be said that, owing to the development of the round ligament, the
broad ligament possesses no true edge, but that the Fallopian tube has
developed its own proper mesosalpinx of considerable length springing
from that surface of the broad ligament which would be described as the
internal surface in quadrupeds. If the mesosalpinx be regarded as a
separate structure, and for the moment neglected, this internal surface of
the broad ligament may be described as running inwards and backwards,
i.e. towards the vertebral column, with its surface diversified only by a
ridge or fold which encloses the utero-sacral ligament. This so-called
ligament is composed in the main of unstriped niuscular fibre, and the
angle formed by its elevation from the smooth surface of the broad liga-
ment in general is what has been described as a depression in which the
ovary lies; in point of fact, the ovary in health and in the living subject

is maintained in a position considerably anterior to this depression by the.

a oe ee

Three Cases of Reappearance of Ovarian Peritoneal Sacculation 311

contractility of its own intrinsic supports, and after study of these relations

in a now considerable number of cases on the living woman I feel con-
fident that this so-called depression bears no more than an accidental
relation to the ovary, which is, in fact, in the normal human female in
contact with a broad ligament which shows no trace of an ovarian
depression.

This view is supported by a fact of great significance. The ovary in
all Mammalia is, as has been said, attached to the broad ligament only by
its hilum and hangs dependent therefrom. In the position commonly
oceupied by the human female the ovary drops towards the vertebral
column and therefore towards the utero-sacral ligaments, but if the woman
be placed in the position of the quadrupeds the ovary would necessarily

hang away from the utero-sacral ligament and towards the situation of the

Fic. 1.—a, diagrammatic sketch of peritoneal relations of ovary
in Case 2; b, diagram of probable cross section.

Fallopian tube, that side of the ovary which in the ordinary position is in
contact with the peritoneum of the broad ligament being now away from
it, and the groove formed by the elevation of the utero-sacral ligament

being therefore at a distance from the ovary, and from the site of its rela-

tion to the peritoneum of the broad ligament. It is difficult to believe that
an elevation in the broad ligament (that due to the utero-sacral), situated
on the other side of the broad ligament from the position of the tube, can
be in any way homologous to the depression near the orifice of the
Fallopian tube which is believed to represent the first stages of the forma-
tion of the ovarian sacculus in the quadrupeds.

It seems, then, that the human female may be described as an animal in
whom the ovary normally possesses the simplest of all peritoneal relations,
that of an ovary hanging in contact with a broad ligament in which no
depression is visible.

I have found no reference to a variation from this normal absence of

312 Dr Edward Reynolds

sacculation in the human female, but I wish to place on record three cases,
all observed on the living subject, in each of which the right ovary was
nearly completely sacculated.! In the instance first observed the sig-
nificance of the condition was not understood and only a verbal deserip-
tion was recorded. In the other two cases the exigencies of the operation
prevented the making of a sketch during the actual exposure of the organs,
but in each case an effort was made to fix upon the mind the exact visual
image, and a sketch of the conditions found was made immediately after
the completion of the operation (figs. 1 and 2). These sketches are
necessarily somewhat incomplete as to details, but I feel confident that
those details which were inserted are correct.

In all three cases the operation was undertaken for the relief of pain
caused by pathological enlargement of the ovary and the tension con-

a

Fia. 2.—Sketch of Case 3, with resected ovary elevated by forceps
and mouth of sacculus consequently stretched open.

sequent upon the development of this condition within the comparatively
rigid confines of the sae.

In the second case operated upon, the accessory peritoneal cavity
consisted of a deep groove between two folds of the broad ligament, «e. of
a cavity the opening of which extended its entire length and was consider-
ably longer than the longest diameter of the enlarged ovary. The extremely
diagrammatic sketch appended gives some idea of the anatomy. Greater
detail was not possible, as the conditions of the operation made visual
inspection of the anomaly difficult and intermittent, and the sketch is com-
piled partly from visual inspection and partly from what was obtained by
digital touch. The latter process is, however, to the skilled touch in some
respects more illuminating than ocular inspection, more especially in regard
to the shape of the cavity and the construction of its walls.

In the third case, illustrated by a less diagrammatic sketch (fig. 3),
continuous and clear inspection was obtained and supplemented by the

’ Note that in many Vertebrates the right ovary is normally undeveloped,

ee i ie.

Three Cases of Reappearance of Ovarian Peritoneal Sacculation 313

touch: In this case the orifice of the sacculus was considerably shorter

than its cavity. The entire ovary and the fimbriated extremity of the
Fallopian tube were hidden within the cavity, and the ovary in its enlarged
state was so much larger than the orifice that it was possible to with-
draw it only by working it around within the capsule until it presented
by one pole, when it was withdrawn by traction on the utero-ovarian
ligament.

In the first case operated upon, my recollection of the appearances and
conditions, which seems to me very vivid, were that they were closely
similar to those of the case last described, which impression is confirmed by
the verbal description recorded at the time.

Fic. 3.—Diagrammatic section through broad ligament of Case 3,
parallel to mesial section and cutting sacculus.

r, round ligament ; s, salpinx ; u.s., utero-sacral.

The relations between the situation and anatomical construction of the
pouches in these three cases, and the situation and anatomy described by
Robinson for the Vertebrates, in which these saccule are normal, is of
interest. |

According to Robinson, the mesial layer of the broad ligament in the
quadrupeds always contains two strands of fibrous tissue, which were
perhaps better described by Owen as the anterior and posterior portions of
the same (ovarian) ligament. They should properly be considered as one
ligament, since their extremities evidently coalesce in the hilum of the
ovary, and their function is the support of this organ. The outer portion
extends in the quadrupeds from the posterior extremity of the ovary to the
tip of the cornu uteri. The anterior portion extends forward from the anterior

314 Dr Edward Reynolds

extremity of the ovary, and is either lost in the broad ligament on the outer
side of the kidney or passes forward to the diaphragm.

In the human subject the uterine extremity of this ovarian ligament does
not arise from the cornu of the uterus, but from the lateral edge of the organ
at a somewhat variable position, usually near the lower part of the corpus,
occasionally as high as perhaps a half-way position between the cornu and
the situation of the internal os, the lowest portion of the corpus. (It must
here be remembered that in the human subject a considerable portion of the
volume of the uterus is made up of a differentiated cervix, which is either
of little size or almost undifferentiated in the other mammals.) The anterior
extremity of the ligament is lost in the subperitoneal tissues at about the
brim of the pelvis and a little to the outer side of the ureter. In the human
female this so-called ligament has been shown of recent years to be largely
composed of unstriped muscular tissue.

In the quadrupeds, or at least in those few species which I have been able
personally to inspect, these two ligaments or portions of a ligament lie at a

considerable angle to each other with the ovary at the apex of the angle, and.

the third or anterior edge of the triangle is formed by the Fallopian tube.
This arrangement is shown in each of Robinson’s figures. Robinson states
that the ovarian pouch or sac is formed in this triangle, its walls consisting
of reduplications of peritoneum about the two portions of the ligaments and
the base of the Fallopian tube. The ovarian ligament is thus always in the
vertebral or dorsal (medial) wall of the pouch, and it must be noted here that
in the ordinary position of the quadruped the ovary is ventrally dependent
from this ligament, thus falling into the pouch so formed.

In the human female, on the other hand, the two portions of the ovarian
ligament are in the same line, 2.e. the ligament as a whole is straight, and in
the ordinary position of the woman the ovary is dorsally dependent, 2.e.
falling away from the Fallopian tube, instead of towards it as in the
quadruped.

In all three of my cases the Fallopian tube entered the slit at its outer
(in quadrupeds anterior) end, and both portions of the ovarian ligament could
be seen to enter the inner and outer ends of the slit. In the first two cases
it did not occur to me to ascertain whether the ovarian ligament, 2. that

portion of the ovarian ligament which is contained in the hilum of the

ovary, lay in the outer or inner wall of the pouch, but since the relation of
the ovary to the tube and broad ligament in general after its extraction
from the pouch was precisely similar in all three cases, it is probable that
the relation of the ovarian ligament to the pouch was in all the cases that
which is shown in the sketch of the third case. In this sketch it is readily
seen that the uterine ligament as a whole is ventral to the opening of the

— a a ee

Three Cases of Reappearance of Ovarian Peritoneal Sacculation 315

slit, i.c. that the hilum and the ovarian ligament lie in what would be
- described in animals as the outer wall of the pouch,—a situation in which the
ovary would fall into the pouch by gravity in the ordinary position of the
woman,—while both my own observations and Robinson’s figures show that
in the quadrupeds the hilum and the ovarian ligament are on the dorsal edge
of the pouch, 7.e. contained in its inner wall. In the ordinary position of
the quadruped this arrangement would again ensure the ovary’s dependence
into the pouch under the influence of gravity.

This alteration of the relation of the sac to the ovarian ligament
suggests a correlation with the altered habitual attitude of the species, in
all other respects the ovarian sacs observed in these three women appear
to be homologous with the sacs which are normal in so many of the

, quadrupeds.

OMPHALOPAGOUS TWINS IN THE HUMAN SUBJECT.
By Dr James F, GEMMILL and Mr JAMES STEWART.

ConcLusion.—Ventral union, limited (as far as the parietes are concerned)
to the umbilical region, can occur in human twins, and accordingly the
type Omphalopagus should receive a place in the classification of Mam-
malian Double Monstrosities, its position being intermediate between
Xiphopagus and Lecanopagus or Ischiopagus.

DESCRIPTION OF SPECIMEN.

The specimen consists of full-time female twins united face to face in
the umbilical region by an isthmus which expands mesially to form a sac
of considerable size. In each twin the epidermis of the body wall extends
over the neck of the isthmus and over a small portion of the sac, but not
more than a quarter of the total surface of the sac has natural skin over it,
the remainder being covered by a thin, pinkish, semi-transparent membrane.
Both subjects are in rather an emaciated condition and one of them has well-
marked talipes varus on the left side. There is no anal aperture in either
case, but the twin with the club-foot shows an anal depression. The labia
are well developed, and on separating them a distinct opening is seen in each
case. This has proved to be the external opening of the urogenital canal.

Measurements.—Length from top of head to coccyx, 28 to 30 em. Full
length when stretched out, 62 to 63 em. Circumference of common sac,
27°5 em. Circumference of neck of isthmus in club-foot twin, 18 em.;
in other twin, 8 cm.

Only one umbilical cord is present, its place of origin being the middle
of the common sac, on the side away from the club-foot. A cut edge of
membranous tissue running transversely round the sac is probably a
remnant of the fused amnia.

The twins had a common placenta and a short common umbilical cord.
They survived for several days. A third child, born shortly after them,
had separate membranes and placenta, was healthy and well developed, and
is still alive.

The clinical aspect of the case has been described elsewhere (Laneet,
London, April 1, 1916) by Dr Robert Jardine, in whose wards at the
Glasgow Maternity Hospital the birth oecurred, and through whose

Omphalopagous Twins in the Human Subject 317

courtesy and that of Professor T. H. Bryce the specimen was handed to
us for examination.

Peritoneal Cavities and Mesenteries——The peritoneal cavities of the
twins communicate freely in the central mass, which consists chiefly of coils
of intestine. The dorsal mesentery is retained throughout, except that the
commencement of the duodenum is bound down to the posterior abdominal
wall near the middle line. The great omentum is absent, but in both twins
there is a wide epiploic foramen leading into a peritoneal recess lying
behind the stomach and clothing about half of its posterior aspect.

"Ol. Fe.
Fic. 1.—Outline drawing of specimen, showing the general character of the union.

Alimentary Canal.—In both twins the small intestines proceed in coils
through the stalk into the central mass, where they unite 2°5 em. from the
ileo-czecal junction. The common canal opens into a large cecum which
shows two vermiform appendices, each appendix being placed slightly to
the left of the mesentery coming from the twin to which it belongs. The
cecum and colon are very greatly distended with fecal material. The large
intestine is 23 em. long, its lumen admitting the passage of two fingers.
It is contained within the central mass, but towards its termination it sends
a short horn into the pelvis of the twin without the club-foot, the horn
being continued as a solid fibrous band in the direction of the anal depres-

sion previously noted as being present in this twin.
VOL. L. (THIRD SER. VOL, XI.)—JULY 1916. 21

318 Dr James F. Gemmill and Mr James Stewart

Vascular System.—No branches of the superior mesenteric arteries
proceed to the cecum or the colon, which are entirely supplied by the
inferior mesenteric arteries. These vessels pass through the connecting
stalk into the central mass, where, after branching repeatedly, they are
distributed each to its own side of the intestine. A superior hemorrhoidal
branch is absent. Three of the hypogastric or allantoic arteries are of
large size and enter the umbilical cord, while the remaining one, namely,

Fie. 2.—Common cecum and fused portion of intestine opened up. The appendix
of the twin without the club-foot is on the left of the figure, while the opening
into the appendix of the club-foot twin is shown in the floor of the cavity.

the right hypogastric artery of the twin without the club-foot, is a small
vessel which becomes lost on the abdominal wall of this twin in the region
of the isthmus neck. Two umbilical veins are found in the root of the
cord, one coming from each twin.

Urogenital System.—In both twins all the Miillerian duct derivatives
are doubled, the Fallopian and uterine tubes in each being widely separated
from one another, the latter opening into vagine dilated with fluid. The
vagin open in turn into the urogenital canal, and the contained fluid was
found to have plentiful urinary salts in solution.

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320 Dr James F. Gemmill and Mr James Stewart

In the central mass, below the insertion of the umbilical cord, is a large
principal bladder with two necks, one passing downwards into the pelvis of
each twin and continued into a corresponding urogenital canal. This
bladder receives the two ureters of the club-foot twin, but only the left
ureter of the second twin. The last-named twin has its right ureter

opening into a small accessory bladder in the right hypogastric region.

This bladder is surmounted by a small urachus, and opens through a short
narrow passage into the body of the principal bladder. It will be
remembered that the right hypogastric artery.of the same twin was small

Fal. 7b.

UGS.

Fic. 4.—Diagram of urogenital system of twin without the club-foot, showing the
various openings into the sal dets and urogenital sinus. In the case of the
club-foot twin the arrangement is similar, except that no accessory bladder is
present, both ureters opening into the principal bladder.

and did not pass into the neck of the isthmus. The urachus and small
hypogastric artery, just referred to, hint at a second but altogether
rudimentary umbilical complex on the side of the isthmus opposite to that
on which the functional umbilical cord is placed. The two necks of the
principal bladder lead each into a urogenital passage which, after receiving

the openings of a pair of vaginz, comes to the surface between the labia
majora..

DISCUSSION.

The specimen belongs to the “Siamese Twin” group of monsters, in
which there is anterior and posterior doubling (A nakatadidynws, Forster (5)),

ee ae

Omphalopagous Twins in the Human Subject 321

the union being on the whole a face-to-face or ventral one. In this case
the union is exactly face to face, except for the fact that the umbilical cord |
is single and comes off from one side of the central mass.

With the doubtful exception referred to below, our specimen appears to
be unique among mammalian monstrosities, since no example of “ Siamese
_ Twins” has so far been described in which the union is confined to the
- umbilical region, leaving the skeletal structures of both sternum and pelvis
entirely unconnected with one another. Thus in Saint-Hilaire’s classification
(7, pt. iii. p. 67) the group of monsters which might be expected to include
the specimen deseribed in this paper, contains the following types: Jschio-
pagi, Xiphopagi, Sternopagi, Ectopagi (i.e. with lateral union along whole
of thorax), Hemipagi (i.e. with lateral union along whole of thorax and
neck), Similarly in Schwalbe’s (8, p. 113) classification, the group into
which our specimen should fall is subdivided as follows: Prosopothoraco-
pagus, Thoracopagus, Sternopagus, Xiphopagus, Ileoxiphopagus, Ileo-
thoracopagus, Cephalo-ileo-thoracopagus. There is a similar blank in the
classificatory systems of other authors, eg. Forster (5), Ahlfeld (1),
Stewart (9), Taruffi (10), and Ballantyne (3). Cleland’s sub-type, Union
confined to the neighbourhood of a common wmbilicus, contains but is
wider than Omphalopagus, since it includes also the xiphopagous Siamese
Twins (4, p. 134).

The term Omphalopagus was introduced by Geoffroy Saint-Hilaire (7,
pt. iii. p. 107) to describe a double monster chick in which there was superficial
union in the umbilical region by the anterior portion of the vitellus. He
_ adds that a double human fcetus figured by Aldrovandi (2) is the only other
example of this kind of monstrosity he could find described. Aldrovandi’s
figure shows twins united by a narrow isthmus at the umbilicus; one of
them having only a single hind-limb, a right limb to judge by the figure.
The description (2, p. 634) is as follows: “ Pariter in Pago Vallis superioris
Arni Tertanio nuncupato, anno salutis humane post millesimum, et trecen-
tesimum decimo sexto monstrum natum est referens duos Gemellos umbilico
copulatos, quorum alter duo crura, alter vero unum tantummodo habebat
ut in Icone I ostenditur.” Doubt has been thrown by Taruffi on the correct-
ness of Aldrovandi’s figure, on the ground that the monstrosity had been
previously figured by Licosthenes not ad naturam but from a somewhat
more detailed description than that given by Aldrovandi. Taruffi believes
the specimen was really an example of Dicephalus tripus tetrabrachius
(10, pt. ii. p. 574).

The omphalopagous type of monstrosity finds its best illustration among
the osseous fishes. In the trout and salmon, for instance, union of sym-
metrical twins by the yolk-sac only is by no means uncommon (Gemmill, 6),

322 Dr James F. Gemmill and Mr James Stewart

and in rare cases survival for a time may occur. As Geoffroy Saint-Hilaire
(7, pt. iii. p. 107) pointed out, omphalopagous union can readily occur where-
ever the egg is large and the yolk-sac is not cast off but taken into the
body.

It need hardly be said that the twins are unioval in origin. Probably
the germinal areas from which they developed were situated opposite
to one another on the wall of the blastocyst. There may have been only
one entodermic sac, but more probably there were two such sacs which
became confluent posteriorly on their ventral aspects. The fused portion
of intestine in our specimen corresponds with the tract normally developed
behind the origin of the omphalo-mesenteric duct from the apex of the
primitive umbilical loop of intestine. The great hernia into the central sac
recalls in exaggerated form the exomphalic condition of portions of the
alimentary canal, which is characteristic of the earlier stages of human
development.

We may note that instances of simple bifurcation of the umbilical cord
(i.e. funicular union) may occur in the case of homologous twins (Ahlfeld, 1,
p. 17). In our specimen the cord and placenta were unfortunately not
available for microscopical examination, so that we cannot say whether
a yolk-sac and vitelline duct were present. It would appear, however
(Ahlfeld, 1, p. 17), that homologous twins sometimes possess completely

separate yolk-sacs. :
ABBREVIATIONS.

Ace, Bl. . . Accessory bladder. R. Umb. Cd. . Rudimentary umbilical

Acc, Umb, Cd, Accessory umbilical cord. cord.

Am... . . . Amnion. Rt. Hyp. Ar. . Right hypogastric artery.

Ao. . . . . Dorsal aorta. Rt. Ur.. . . Right ureter.

Cl. Ft... . . Club-foot. Rt. Ut.. . . Right uterus.

Col... . . . Fused colon. Rt. Vag. . . Right vagina.

Fal. Tb. . . Fallopian tube. St. . . . . Connecting stalk.

\ Acre ie U. GS. . . Urogenital sinus.

fl. C.V. . . Tleo-colic valve. Umb. Cd. . . Umbilical cord.

Lt. Hyp. Art.. Left hypogastric artery. | Umb. V. . . Umbilical vein.

Lt. Ur.. . . Left ureter. Un. Int. . . Fused part of intestine.

it. Ut.. . . Left uterus. Or. oe.) > 4 reter.

It. Vag. . . Left vagina. Urach.. . . Urachus.

Op. Bl.. . . Opening of bladder into| Vag. Op. . . Opening from uterus into
urogenital sinus. vagina.

Os Ut. . . . Os uteri. Ver. App. . . Vermiform appendix.

Pr. Bl. . . . Principal bladder.

——————— ee ll

Omphalopagous Twins in the Human Subject 323

REFERENCES.

1. AutFELD, Die Misshildungen des Menschen, Leipzig, 1880.

2. ALtpROVANDI, Monstrorum Historia, Bologna, 1642.

3. BautantynE, J. W., Antenatal Pathology and Hygiene, “The Embryo,”
Edinburgh, 1904.
. CLELAND, J., Memoirs and Memoranda of Anatomy, London, 1889, p. 134.
. ForsTER, Avausr, Die Missbildungen des Menschen, Jena, 1861, p. 34.
GemMiLL, James F., The Teratology of Fishes, Glasgow, 1912.
Sarnt-Hinarre, Grorrroy, Histoire des Anomalies, Paris, 1836.
Scuwa Be, Ernst, Morphologie der Missbildungen, Jena, 1906.
. Stewart, C., Catalogue of Teratological Specimens in Museum of Royal College
of Surgeons, London, 1893.

10. Tarurri, Cesare, Storia della Teratologia, Bologna, 1881.

2 ID Ot

A PALMARIS LONGUS MUSCLE WITH A REVERSED BELLY,
FORMING AN ACCESSORY FLEXOR MUSCLE OF THE
LITTLE FINGER. By Captain Jonn T. Morrison, F.R.CS.
R.A.M.C., Pathologist, Royal Southern Hospital, Liverpool.

(Liverpool Merchants’ Hospital, B.E.F., France.)

DuR1NG the dissection of an arm, amputated for a severe compound fracture
of the humerus, a curious muscle was found lying in front of the left
wrist.

Description.—Taking origin from the tendon of the palmaris longus
about 2 inches above the wrist, it passed as a small somewhat flattened
muscle belly, distally and medially, into the palm of the hand. It lay first
upon the tendons of the flexor sublimis digitorum, and then crossed the
anterior carpal ligament, keeping close to the os pisiforme. When the
muscle had been hardened in sitw this bone was found to have left-a
distinct indentation upon its medial border.

About one-quarter of the distance from the pisiform to the base of the
5th metacarpal, the muscle belly tapered off into a delicate tendon which
ran on between the abductor minimi digiti and the opponens. With both
muscles it finally blended, receiving a common insertion into the base of
the proximal phalanx of the little finger on its medial side. A fascial
expansion passed to the common extensor tendon on the dorsal aspect of
the joint.

In the photograph a rod is seen passed under the tendon of the
palmaris longus. The palmaris brevis has been reflected and the mesial
portion of the palmar fascia dissected away to show the entire length of
the muscle.

Nerve Swpply.—The nerve supply was double. Two minute twigs, both
from the ulnar nerve, entered its substance. One of these was given off
above the level of the wrist joint and entered its deep surface; the other,
an offshoot from the branch of the ulnar to the medial border of the little
finger, entered the muscle just below the pisiform on its medial border.
The trunk of the median nerve lay in direct contact with the deep surface
of the muscle as it crossed the anterior carpal ligament.

Blood Supply.—The arterial supply came from the ulnar artery and
accompanied the nerves. .

A Palmaris Longus Muscle with a Reversed Belly 325

Action.—When this muscle contracted it must have resulted in strong
flexion of the small finger with a distinct tendency towards opposition. It
can only have exerted its maximum power, of course, when the palmaris
longus was also in contraction.

Remarks.—The patient, a soldier, had been in civil life a labourer. He
told me afterwards that he had never noticed anything unusual about his
left hand or its little finger. It had not been stronger or more useful than
the right. His other hand was carefully examined, but no trace of a

similar muscle could be seen, although his palmaris longus was strongly
developed. There did not seem to be anything unusual in the range,
power, or delicacy of movement in the little finger of the right hand, nor
were any other bodily peculiarities discoverable.

The muscle described above is doubtless an additional belly of the
palmaris longus. This extremely variable muscle is said to be occasion-
ally digastric, and to have insertions into the muscles of the thumb or little
finger.

VoL. L. (THIRD SER. VOL. XI.)—JULY 1916. 52

—

326 A Palmaris Longus Muscle with a Reversed

Norr.—The digastric condition of palmaris is very
with a long tendon of origin and a reversed
map i and this seems to be the condition ex: si
the examples of this reversed palmaris it coexists
differs in having an ulnar nerve-supply.

Quary’s Anatomy, 10th ed., vol. ii. Be
Joun Woon, “ Variations in Human ais leer
xiii, eS xvi.

Arteries of the pons and medulla oblongata,
J.S. B. Stopford, M.D., 131, 255.

Artery, the thyroidea ima, G. Wyatt Pratt,
B.A., 239.

_--_—_—_—_—sC Barbosa, Dr José Martins, sur la structure du
____ poumon du Dauphin (Delphinus delphis), 285.
Barrington, F. J. F., the mucinous changes of
___ the vaginal epithelium of certain mammals in

_-_-~pregnancy, 30.

Blastoderm, the structure of the, and the
continuity of the cell-elements during the

early stages of development, Professor J.

be Cameron, M.D., D.Se., and R. J. Gladstone,

‘M.D., F.R.C.S., 207.

Bryant, W. Sohier, A.M., M.D., the transition
of the ciliated epithelium of the nose into the
squamous epithelium of the pharynx, 172.

Bryce, Professor T. H., the West Scottish skull,
243.

Cameron, Professor J., M.D., D.Se., and R. J.
Gladstone, M.D., F.R.C.S., the structure of
the blastoderm, and the continuity of the cell-
elements during the early stages of develop-
ment, 207.

Cast and brain form, endocranial, a criticism of
some recent speculations, Professor J. Syming-
ton; M.D., F.R.S., 111.

Chase, Martin R., M.D., congenital deficiency

_ of the pericardium, 299.

Collinge, Walter E., M.Sc., F.L.S., ete., some
abnormal developments in the vascular system
of the frog (Rana temporaria), 37.

Gadenttal delicioncy of the pericardium, Martin
R. Chase, M.D , 299.

Costal musculature, the, Thomas Walmsley,
M.B., 165.

Developmental changes in the pericardium, the
mesocardia, and the pleural sacs in the human
embryo, David Waterston, M.D., 24.

_ Diaphysial growth in proximal and distal
directions, the measurement of, Professor
Kenelm H. Digby, M.B., F.R.C.S., 187.

Digby, Professor Kenelm H., M.B., F.R.C.8.,
the measurement of diaphysial growth in
proximal and distal directions, 187.

INDEX

Drinkwater, H., M.D., M.R.C.S. Eng., F.L.S.,
hereditary abnormal segmentation of the index
and middle fingers, 177.

Embryo, developmental cha in the peri-
cardium, the mesocardia, and the pleural sacs
in the human, David Waterston, M.D., 24.

Endocranial casts and brain form : a criticism of
some recent speculations, Professor J. Syming-
ton, M.D., F.R.S., 111.

Female, three cases of reappearance of ovarian
peritoneal sacculation in the human, Edward
Reynolds, M.D., 308.

Femur, observations on the popliteal groove on
the, Gilbert I. Strachan, M.D., 204.

Fingers, hereditary abnormal segmentation of
the index and middle, H. Drinkwater, M.D.,
M.R.C.S. Eng.. F.L.S., 177.

Frazer, J. Ernest, F.R.C.S., and R. H. Robbins,
M.D. Cantab., on the factors concerned in
causing rotation of the intestine in man, 75.

Frog (Rana temporaria), some abnormal develop-
ments in the vascular system of the, Walter
E. Collinge, M.Se., F.L.S., ete., 37.

Galeopithecus, the genitalia of, Professor
Frederic Wood Jones, D.Sc., 189.

Gemmill, Dr James F., and Mr James Stewart,
omphalopagous twins in the human subject,
316.

Genial tubercles on the mandible of man, and
their suggested association with the faculty
of speech, on the presence of, Professor
Arthur Thomson, .43.

Genitalia of Galeopithecus, the,
Frederic Wood Jones, D.Sc, 189.

—— the homologies of the chelonian and mam-
malian types of, Professor Frederic Wood
Jones, D.Se., 1.

Gladstone, RK. J., M.D., F.R.C.S., and Professor
J. Cameron, M.D., D,Se., the structure of the
blastoderm, and the continuity of the cell-
elements during the early stages of develop-
ment, 207.

— and ©. H. Reissmann, M.A., M.D.,
M.R.C.P., B.Sc., two examples of cardiac mal-
formation, 228,

Professor

330 Index

Hepworth, F. A,, M.A., M.B.Camb., F.R.C.S.,
au unusual peritoneal sac, 293.

Hereditary abnormal segmentation of the index
and middle fingers, H. Drinkwater, M.D.,
M.R.C S. Eng., F.L.8., 177.

Homologies of the chelonian and mammalian
types of genitalia, Professor Frederic Wood
Jones, D.Se., 1.

Human embryo, developmental changes in the
pericardium, the mesocardia, and the pleural
sacs in the, David Waterston, M.D., 24.

In memoriam: Principal Sir William Turner,
K.C.B., F.R.S., ete., 1882-1916, 281.

Intestine in man, on the factors concerned in
causing rotation of the, J. Ernest Frazer,
F.R.C.S., and R. H. Robbins, M.D. Cantab.,

7

on

Jones, Professor Frederic Wood, D.Sc., -the
homologies of the chelonian and mammalian
types of genitalia, 1, 189.

—— the genitalia of Galeopithecus, 189.

Kesteven, Dr H. Leighton, the relations of the
amphib an parasphenoids, 303.

Malformation, two examples of cardiac, R. J.
Gladstone, M.D., F.R.C.S., and C. H.
Reissmann, M.A., M.D., M.R.C.P., B.Sc.,
228.

Mandible of man; the suggested association of

its genial tubercles with the faculty of speech,

Professor Arthur Thomson, 43.

Measurement of diaphysial growth in pr ximal
and dista] directions, Professor Kenelm H.
Digby, M B., F.R.C.S., 187.

Morrison, Captain John T., F.R.CS.,
R.A.M,C., a palmaris longus muscle with a
reversed belly, forming an accessory flexor
muscle of the little finger, 324,

Mucinous changes of the vaginal epithelium of
certain mammals in pregnancy, F. J. F.
Barrington, 30.

Muscle, a palmaris longus, with a reversed belly,
forming an accessory flexor muscle of the
little finger, Captain John T. Morrison,
F.R.C.8., R.A.M.C., 324.

Musculature, the costal, Thomas Walmsley,
M.B., 165.

Observations on the popliteal groove on the
femur, Gilbert I. Strachan, M.D., 204.

Omphalopagous twins in the human subject,
ie caie F. Gemmill and Mr James Stewart,

On the factors concerned in causing rotation of
the intestine in man, J. Ernest Frazer,
oe and R, H. Robbins, M.D. Cantab.,
5.

On the presence of genial tubercles on the
mandible of man, and their suggested associa-
tion with the faculty of speech, Professor
Arthur Thomson, 43, :

Palmaris longus muscle, a, with a reversed belly,
forming an accessory flexor muscle of the
little finger, Captain John T. Morrison,
F.R.C.S., R.A.M.C., 324. .

Parasphenoids, the relation of the amphibian,
Dr H. Leighton Kesteven, 303.

Pericardium, congenital deficiency of the,
Martin R. Chase, M.D., 299,

Pharynx, the transition of the ciliated epithelium
of the nose into the squamous epithelium of
the, W. Sohier Bryant, A.M., M.D., 172.

Popliteal groove on the femur, observations on
the, Gilbert I. Strachan, M.D., 204,

Pratt, G. Wyatt, B.A., the thyroidea ima
artery, 239.

Pregnancy, the mucinous changes of the vaginal
epithelium of certain mammals in, F, J. F.
Barrington, 30. :

Reissmann, C.~H., M.A., M.D., M.R.C.P.,
-B.Se., and R. J. Gladstone, M.I)., F.R.C.S.,
two examples of cardiac malformation, 228.
Relation of the amphibian parasphenoids, the,

Dr H. Leighton Kesteven, 303.

Reynolds, Edward, M.D., three cases of re-
appearance of ovarian peritoneal sacculation
in the human female, 308.

Robbins, R. H., M.D. Cantab., and J. Ernest
Frazer, F.R.C.S., on the factors concerned
in causing rotation of the intestine in man,

—
ic.

Sac, an unusual peritoneal, F. A. Hepworth,
M.A., M.B. Camb., F.R.C.S., 293.

Skull, the West Scottish, Professor T. H, Bryce,
241.

Stewart, Mr James, and Dr James F. Gemmill,
omphalopagous twins in the human subject,
316.

Stopford, J. S. B., M.D., the arteries of the
pons and medulla oblongata, 131, 255.

Strachan, Gilbert I., M.D., observations on the
popliteal groove on the femur, 204,

Structure of the blastoderm, and the continuity
of the cell-elements during the early stages of
development, Professor J. Cameron, M.D.,
D.Sc., and R. J. Gladstone, M.D., F.R.CS.,
207.

Sur la structure du poumon du Dauphin (Del-
phinus delphis), Dr José Martins Barbosa,
285.

—

- rae J., M.D., F.RS., endo-
erantal casts and brain form: a criticism of
" i sees setent speeten, 111.

: nfigton, on

Micsansin Professor Arthur, on the presence of
enial tubercles on the mandible of man, and
ir suggested association with the faculty of

‘Reynolds, M.D., 308
gies, the, G. Wyatt Pratt,

he 239.
“Transition of the ciliated epithelium of the nose
into the squamous epithelium of the pharynx,
Sobier Bryunt, A.M., M.D., 172.
, Principal Sir William, K.C. B., F.R.S
., 1832-1916, in memoriam, 281.

Index

331

Two examples of cardiac malformation, R. J.
Gladstone, M.D., F.K.C.S., and C. H.
Reissmann, M.A., M.D., M.R.C.P., B.Sc.,
228.

Vascular system of the fi (Rana temporaria),
some abnormal devel He mts in the, Walt
E. Collinge, M.Sc., F.L.S., ete., 37.

Walmsley, Thomas, M.B., the costal muscula-

ture, 165, ;
Waterston, David, M.D., developmental
chauges in the ium, the mesocardia,

and the pleural sacs in the human embryo,
24,

West Scottish skull, the, Professor T. H.
Bryce, 243,

‘

PRINTED IN GREAT BRITAIN BY NEILL AND CO., LTD., EDINBURGH.

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we

PROCEEDINGS OF THE

ANATOMICAL SOCIETY OF GREAT BRITAIN
AND IRELAND

JANUARY 1915

MEETING held on Friday, January 29, 1915, at the Royal College of
Surgeons, Lincoln’s Inn Fields; the President, Professor Howden, in the
chair. Twenty-two members and eight visitors were present.

Two new members—Miss Grace Hamilton Ewart and Mr James Berry,
F.R.C.S.—were elected.

(1) Mr R. H. Burne exhibited a reconstruction model of great historic
interest inasmuch as it was the first of its kind to be produced in England.
The actual model has been presented to the Museum of the Royal College
of Surgeons by its maker, Mr E. T. Newton, of the Geological Survey. It
was made in 1879, and represents the enlargement of the brain of the
cockroach (Periplaneta orientalis) cut into thirty-five coronal sections.
The plates of which the model is built up are made of thin slices of wood
on which magnified drawings of the sections were pasted. Great ingenuity
is shown in the subsequent treatment of the plates, which is different upon
the two sides of the brain. Although not the first attempt at reconstructive
microscopical methods, this model was produced quite independently of
any knowledge of the work of Born, who had made reconstructions of the
amphibian nasal cavities, and published his results in Germany two years
before Mr Newton completed his model.

Wood was used by Mr Newton for his plates because (and the finished
model bears every evidence of this) he was a master in the technique of
wood carving.

Professor E. Fawcett recalled the fact that His and others had made
early attempts at reconstructions with the same material.

(2) Professor ArrHUR KerTH exhibited a series of specimens recently
added to the Museum of the Royal College of Surgeons.

(3) Professor ArtHuR KeirH also gave a preliminary account of a
search for a representation of the “nodal” system of the heart in the

2 Proceedings of the Anatomical Society

muscular walls of the alimentary tract. His research was guided by the
following considerations. It may be regarded as definitely proved that.
“nodal” tissue as seen in the sino-auricular and auriculo-ventricular nodes
is endowed to a high degree with the power of initiating waves of contrac-
tion. It was less clearly proved that the tissue of the auriculo-ventricular
bundle itself, or of the terminal twigs of the bundle which unite with the
musculature of the ventricles, possessed to a special extent the power of
initiating contraction; but it was usual to ascribe such a property to the
substance of the terminal twigs. It was at least necessary to distinguish
between what may be called “initial nodal” tissue—such as that of the
“S.A.” or of the “A.V.” nodes—and what may be called “terminal nodal”
tissue, forming the terminal twigs of the “A.V.” bundle. The heart-
being composed of highly specialised muscle, Professor Keith expected to
find more simple representations of those “nodal” systems in more
primitive muscular organs such as the stomach and bowel.

The ileo-czecal junction of the rat’s intestine was selected for the first
inquiry because many of the cecal movements seemed to be initiated at
that point, and also because of the tonic and contracted functional state of
the ileo-czecal sphincter. Serial sections showed a ring—representing a
thickening of Auerbach’s plexus—surrounding the termination of the ileum ;
the tissue of the ring contained many ganglionic cells, but also a greater
number of cells which were apparently not ganglionic in nature ; the cells of
the second kind—which may be called Koelliker’s cells—appear to become
directly continuous by their processes with the muscle fibres of the ileo-
cecal sphincter. These junctional: cells and processes which link up
Auerbach’s plexus or tissue with the muscle fibres were, in the speaker's
opinion, of the nature of “terminal nodal” tissue.

On the ventral and dorsal surfaces of the cecum—immediately ventral
and dorsal to the termination of the ileam—were two well-marked strips or
borders of nodal tissue, in reality the commencement of the Auerbachian
system of the caecum. These borders are joined by sympathetic fibres
from periarterial nerves, and are also joined by muscle fibres arranged in a
plexiform manner—muscle which in nature and arrangement recalls the
true nodal tissue of the heart.

Auerbach’s plexus is not composed simply of ganglionic cells and
nerve fibres; it contains numerous other cells to which Koelliker called
attention, and which may be described as Koelliker’s cells. These cells
have small bodies which send out numerous branched processes, and differ
from pure sheath cells in staining reaction and in structure. It is through
these cells that Auerbach’s tissue is linked up with the musculature of the
bowel. The nerve fibres which former authors have described as distri-

of Great Britain and Ireland - 3

‘buted to the muscular and other coats of the bowel are probably sensory

in nature. |

Sections of the developing bowel show that the outer and inner muscu-
lar coats are developed from a germinal layer situated between them.
Auerbach’s plexus represents the residue of the germinal or developmental

intermediate layer. Probably the ganglionic cells may be of central origin,

but the cells of Koelliker are apparently undifferentiated muscle cells.

- The nodal and communicating system of the heart arises in the subendo-
cardial tissue, which apparently serves as a germinal or developmental
stratum for the origin of heart muscle. In point of development, Auerbach’s
plexus is similar in origin to that of the A.V. bundle system of the heart,
and in the speaker's opinion they were homologous.

Auerbach’s plexus or system, like the A.V. system of the heart, is
enclosed in a very definite sheath, as Gerota had demonstrated.

As regards the A.V. system of the heart, each group of animals has
its specific form. This is also so as regards the Auerbachian system.
There is no true A.V. system in the bird’s heart. There is, as Dr Ivy
Mackenzie had shown, a muscular union, but that is not comparable
to the mammalian A.V. system. Auerbach’s plexus in the bird’s bowel
appears to be a true nerve system. Dr William Wright had drawn
attention to the peculiar nature of the Auerbachian tissue in the ileo-cecal
Sphincter of the elephant. In Ungulates long leashes from Auerbach’s
plexus are applied to the sides of certain muscular fibres.

The submucous plexus (Meissner’s) is highly developed in Ungulates :
it is much less developed in Primates.

Great intestines excised for various surgical conditions—intestinal stasis,
mucous colitis—had yielded several remarkable conditions of the Auer-
bachian system. In some theré was definite degeneration or atrophy of
the Auerbachian system, in others fibrosis, in others swelling and vacuolisa-
tion of its ganglionic cells.

Discussion,

Professor WRIGHT showed two lantern slides made from photomicro-
graphs of sections of the small and large intestine of the elephant. The
slides showed Auerbach’s and Meissner’s plexuses both well developed.
Professor Wright thought that the high development of Meissner’s plexus
might be correlated with the equally high development of the tunica
muscularis mucosz in the alimentary canal of the elephant.

(4) Professor A. M. PaTrerson showed the skeleton of a recent case of
myositis ossificans. There is almost complete anchylosis of the vertebral
column, the atlas and coccyx alone being free. A rod of new bone further

*

4 Proceedings of the Anatomical Society

extends along the back, fused with the spinous processes. Lateral branching
bars extend outwards from this over the scapular regions and buttocks. The
right scapular bar articulates with a branched exostosis attached to the verte-
bral border of the scapula. Both gluteal bars are fused with the ilium.

There is anchylosis of the lower jaw, and extensive formation of new

bone from the left mandible, resulting after an operation intended for the
relief of the condition.

Many joints show signs of arthritis; and the limb bones are character-
ised by the exaggeration of normal muscle-attachments, and by irregular
exostoses. There is one immense irregular exostosis attached to the front
of the left femur.

Certain carpal and metacarpal bones are fused together. There is
extensive anchylosis of both ankles, and of tarsal and metatarsal bones.

Professor PATERSON also demonstrated the skeleton in the Hunterian
Collection (Royal College of Surgeons of England), exhibited by Professor
Keith. This case shows similar features, but the disease is more advanced.

The spine is rigid, and there are two bony plates added in the back,
connected to the spine and ribs. They join the skull above: the scapule
laterally, and the sacrum and both iliac bones below. F

The lower jaw is connected with the right external pterygoid plate.

The right scapula and humerus are firmly united by a Y-shaped bar of
bone which springs from the shaft of the humerus and is united to the
inferior angle and the spine of the scapula.

The left elbow-joint is completely anchylosed.

The wrist joint on the right side is anchylosed, most of the carpal bones
also being fused together, and with the radius and ulna.

The right femur is fused with both pubis and ischium by a large
irregular bar of bone, which springs from the shaft of the femur and
bifurcates above.

The tibia and fibula are anchylosed together at both ends. The tarsal
bones are anchylosed on each side and are fused with the bones of the leg.

Full accounts of both skeletons will be published later.

Discussion.

Professor A. F. Dixon mentioned that two well-known skeletons, illus-
trating the disease in a very advanced condition, were preserved in Dublin
—one in Trinity College, the other at Dr Steevens’ Hospital. He showed
several photographs and also X-ray pictures of these.

The Trinity College specimen—a male—probably represents the earliest :

recorded case, and first received public attention in a letter written by the
Bishop of Cork to the Earl of Egmont, published in the Philosophical

°

of Great Britain and Ireland : 5

Transactions, 1740-1741 (vol. xli.). Other notices of it have appeared
elsewhere at later dates, and it is the specimen illustrated in the curious
oil-painting preserved in the Museum of the Royal College of Surgeons,
and now exhibited at the meeting by Professor Keith. The late Professor
Bennett was much interested in the condition. He exhibited and described
the skeleton in 1872 at a meeting of the Pathological Society of Dublin
(N\S., vol. v., 1874), when he also showed a cast taken from a girl of eleven.
The latter cast is now in Trinity College. At the same meeting the late
Mr Hamilton, of Dr Steevens’ Hospital, demonstrated the second skeleton—
a female—mentioned above. It had been prepared in the school of the
hospital by Mr Bookey. The specimens very closely resemble one another,
but the Steevens specimen possesses more movement of its parts than the
Trinity College one, in which the disease is more advanced. Both bear a
striking resemblance to the skeleton in the possession of the Royal College
of Surgeons shown by Professor Keith.

The fact that the peculiar ossification was not in the muscles, but in the
fascia of the muscles, was noted in 1872 by Hamilton and confirmed by
Bennett. In both the Dublin specimens the head is fixed by a rod of bone
ascending near the middle line in the region of the ligamentum nuche:
in one (Steevens) the lower jaw is fixed by ossification in the masseteric
region, and in the other (T.C.D.) by bone in the region of the internal
pterygoid. In both skeletons the great toes show the remarkable partial
suppression of the first phalanx to which attention was drawn some years
ago. Professor Bennett demonstrated this condition in a living case
exhibited by him to the Biological Club in Dublin in January 1905, and he
believed it to be characteristic of the disease.

In X-ray pictures the new bone resembles ordinary bone and shows a
definite arrangement of lamellw. Some at least of the bony bars and
masses appear to have been formed in the soft intermuscular connective
tissue rather than in the muscle sheaths. It is remarkable that ligaments
like the great and small sacrosciatic ligaments, the interosseous membranes,
and the ligaments of the hip- and shoulder-joints are not involved in any
of the specimens. .

Professor J. E. S. Frazer mentioned the case of a boy of 10, subject
of this disease, in which the manifestations were more marked upon the
ventral side of the body than, as is usual, upon the dorsal aspect.

(5) Professor F. Woop Jones described the basal type of the genitalia
as it existed in the Chelonian reptiles. In these animals.an intra-cloacal
copulatory organ is present; and the features seen in this form of ex-
ternal genitalia show very close resemblances to the embryonic stages

6 Proceedings of the Anatomical Society

of the Mammalia. It was suggested that a study of the very large and
well-developed structures present in the giant tortoises afforded help
in interpreting the initial stages seen with less definition in the early
embryo of man.
Discussion.

Professor MAcBRIDE observed, in confirmation of the opinion expressed
in the paper, that the male Sphenodon had the power of everting the
cloaca as a definite copulatory organ.

(6) Professor David WATERSTON showed permanent casts in plaster
of Paris which had been prepared from his models of the heart, pericardium,
lungs and pleural sacs, septum transversum, etc.,in two human embryos
3mm. and 6 mm. in length. The originals had been shown at a previous
meeting of the Society, and some figures of the models of the younger
embryo were published in the Jowrnal of Anatomy for October 1914. A
full account of the appearances shown in the models of the older specimen
will be published shortly.

The model of the younger specimen showed a heart consisting of
sinus venosus, single atrium, atrio-ventricular canal, ventricle, bulbus cordis,
and conus arteriosus, and the endothelial tube as-well as the myoepi-
cardial wall is seen. The septum transversum is not yet differentiated
into the various parts which later arise from it.

The pericardial and peritoneal divisions of the coelom communicate freely
with one another, and there is a recessus pneumato-entericus on both right
and left sides.

The model of the older embryo shows a later stage in the development
of the heart, the division of the atrial canal into right and left ostia,
and the division of the cavity of the distal portion of the bulbus cordis,
as well as the bulbar cushions.

The pericardio-peritoneal canals showed the changes which were asso-
ciated with the appearance of the lungs, and the pleuro-pericardial apertures —
were reduced in size.

The models had been prepared by Mr Sidney Boyes, and the expenses
in connection with them had been defrayed by a grant from the Royal
Society.

Professor Waterston intimated that copies of the models shown could
now be obtained at the price of £5, 10s. for the smaller, and £6, 10s. for the
larger model. .

Professor E. Fawcerr, in the discussion which followed, urged the —
desirability of a more precise nomenclature of the parts which Professor
Waterston had demonstrated.

’

ee ST ae ee

3

ee Se eee ee
- ‘ : _ —..

of Great Britain and Ireland 7

3 (7) Professor J. SYMINGTON exhibited numerous endocranial, endodural,

arachnoid, and brain casts of recent man, and explained that the methods
used in the preparation of these casts, and the facts they demonstrated

- with reference to the influence of the membranes of the brain and their

blood-vessels and of the cerebro-spinal fluid in producing certain differ-
ences between an endocranial and a brain east, were described in the
Struthers lecture “On the Relations of the Inner Surface of the Cranium
to the Cranial Aspect of the Brain,” delivered in Edinburgh on the 16th
December 1914. The lecture was in type, and would appear in the
Edinburgh Medical Journal for February 1915, and contain photographs
of some of the casts exhibited. Duplicates of the casts represented in
figs. 3 to 15 and figs. 17 to 18 of this lecture have been presented to the
museums of the Royal Colleges of Surgeons of England and Edinburgh,
where they can be examined by those interested in the subject.

Casts were shown illustrating the marked differences in the develop-
ment of the digital impressions as seen in endocranial casts from subjects
in which no appreciable difference in the complexity of the convolutionary
pattern could be detected. The only cerebral fissures which can, as a rule,
be identified on an endocranial cast are the main stem of the Sylvian
fissure and its posterior branch, the upper and lower temporal fissures, and
those on the orbital surface of the frontal bone. The fissures which cut
into the superior border of the cerebral hemispheres, such as the central
and parieto-occipital, are not indicated on an endocranial cast owing to
their being separated from the bone by some of the following structures,
viz.: the superior sagittal sinus and the lacunz laterales embedded in the
dura mater, the superior cerebral veins, the arachnoid and cerebro-spinal
fluid, and the Pacchionian bodies. The course of these fissures outwards
on the superior aspect of the hemisphere cannot be followed, mainly owing
to the accumulation of the cerebro-spinal fluid on the vault.

A protest was made against the practice of calling endocranial casts
brain casts. This habit was said to be very common amongst palzontolo-
gists. The author referred to the attempts that had been made by
Professors Boule, Anthony, and Elliot Smith to estimate the character
and degree of cerebral development from endocranial casts of the La
Chapelle, La Quina, and Piltdown skulls. He maintained that the deduc-
tions made by Elliot Smith from the first reconstruction of an endocranial
cast of the Piltdown man prepared by Dr Smith Woodward would require
modification if the second reconstruction were accepted as more nearly
correct, since they differ in several important respects.

Certain features of the temporal and parietal lobes of the Piltdown
man, described by Elliot Smith as indicating primitive stages in the

8 Proceedings of the Anatomical Society

evolution of the speech and association centres, and the general statement
that “we must regard this as being the most primitive and the most simian
human brain so far recorded,” appeared to the author to be assumptions
based upon evidence which would not stand scientific examination. Perhaps
additional and more satisfactory proofs than those contained in the
Quarterly Journal of the Geological Society for March 1913 that the Pilt-
down man possessed a brain which exhibited such an interesting stage in
the evolution of the human cerebral cortex, will be submitted to anatomists
when the paper read by Elliot Smith before the Royal Society in February
1914 is published 77 extenso.
Discussion.

Professor G. ELt1iot SMITH did not agree with all the conclusions of the
speaker. He remarked that “the beautiful series of casts which Professor
Symington has shown do not demonstrate anything that anatomists have
not been familiar with for a century at least ; for every time one removes
a carefully hardened brain from the cranium all the points mentioned by
Professor Symington obtrude themselves on the attention.

“Those of us who have made extensive use of cranial casts have re-
cognised the incompleteness of the information to be obtained from most-
modern human casts.

“But because many specimens afford negative evidence is surely no
reason for refusing to recognise positive information of the most definite
character when it occurs.

“As for Professor Symington’s criticism, it is all either wholly ir-
relevant or based upon an erroneous interpretation of perfectly clear state-
ments of mine. The cortical area, injury to which in modern man often
gives rise to loss of the ability to recall names, is not the superior
temporal gyrus, as Professor Symington imagines, and on the strength
of such imagining launches an aimless attack on me.”

MARCH 1915

MEETING held on Friday, March 5, 1915, at St Thomas’s Hospital Medical
School; the President, Professor Howden, in the chair. Twelve members
and four visitors were present.

(1) Dr R. J. GLapsTonE described a specimen in which the descending
colon passed obliquely downwards and to the right, across the vertebral
column into the right iliac fossa, where it became continuous with a large
sigmoid loop. ‘The convexity of this loop was directed upwards and to the

of Great Britain and Ireland ? 9

right. It thus occupied the position usually filled by the cecum and
appendix, and appeared to have prevented the descent of these into the
right iliac fossa. The cecum was symmetrical in form, and the root of the
appendix apical in position. The small intestine was both actually and
relatively to the length of the large intestine unusually short. The ab-
normality was regarded as being due to the persistence of the early foetal
position of the colon and it was suggested by Professor Barclay Smith
that this was primarily due to the feeble development of the small intestine,
the growth of which normally pushes the descending, iliac, and pelvic
portions of the colon to the left.

The surgical importance of the case consisted in the absence of the
colon from the left lumbar and iliac regions, and of the cecum and
appendix from the right iliac fossa. Dr Gladstone suggested that the
position of the colon and of the caecum and appendix should be ascertained
before operating, by means of an X-ray examination, after a “bismuth
meal.”

Discussion.

Professor J. E. S. Frazer remarked that the condition, so far as the
unusual course of the colon was concerned, seemed to be explicable as a
slight modification of the manner in which the small intestine returns to
the abdomen. Professor Frazer said he possessed an embryo of about
26 mm. in which there is possibly an early stage of this condition.
Normally the great gut and its vertical mesentery form a partial septum
in the abdominal cavity extending from pelvis to liver, and the small
intestine, returning to its right-hand side, pushes this over to the left. If,
however, a loop of small gut passes to the left above this septum, there is
a corresponding interference with the movement to the left of a part of
the septum, the rest being pushed over, however, by the remaining coils.

(2) Dr R. J. GuapsTonE showed a specimen of manifestation of an
occipital vertebra.

The anterior arch of the occipital vertebra was represented by two
symmetrically placed bars of bone, which extended obliquely forward
and medially on the under surface of the basi-occipital. They ended
anteriorly in two small tubercles, which were separated from one another
by an interval of 3mm. There was no facet for the dens epistropheus. A
small oval facet was, however, present on the anterior extremity of each
bar, which would most probably have articulated with an upward pro-
longation of the articular facet on the anterior arch of the atlas. The
posterior arch, although less distinct than the anterior arch, was neverthe-
less plainly visible ; it consisted of right and left halves, which did not unite

10 Proceedings of the Anatomical Society

behind, being separated by an interval of about half a centimetre. There
was a slight indication of a transverse process on each side; the processes
were, however, completely fused with the jugular processes of the occipital
bone. The posterior condylar fossee were deep, and there was a large
posterior condylar foramen on each side. The hypoglossal foramina were
of large size and undivided. Dr Gladstone alluded to cases of “arcus
preebasioccipitales ” described by Schumacher and other authors, and said
that they appeared to be due to ossification taking place in the hypo-
chordal arch of an occipital vertebra, which is occasionally seen in front of
the hypochordal arch of the atlas vertebra.

(3) Dr W. GILLiIATr (introduced by Dr J. Cameron) showed abnormali-
ties of the heart, aorta, and its branches from an infant which lived for three
days. The heart exhibited two auricles; the right was normal, whereas
the left was small, consisting almost entirely of auricular appendix. It
also showed an apparently single ventricular chamber (right), but the left
ventricle could be demonstrated as a minute recess, not bigger than a —
pin’s head, in the left auricle.

The foramen ovale was therefore patent, in order to allow the blood-
stream from the lungs to pass into the large right ventricle. The tricuspid ~
orifice was very large and the valves incompetent, as was shown during
life by an unusually loud systolic murmur.

From the large ventricular chamber a vessel of considerable size arose,
which could be clearly shown to be the trunk of the pulmonary artery.
This was indicated by the fact that it was guarded by three semilunar
valves ; also that it gave off the right and left pulmonary arteries and the
ductus arteriosus, which was still patent. It also gave off a small vessel
which passed downwards behind it and bifurcated into the right and
left coronary arteries. This small vessel clearly represented the ascending
aorta, in which, however, the blood-stream was directed downwards.

After giving off these branches the pulmonary artery actually became
continuous with the aortic arch, there being a marked stenosis at the point
of junction. This stenosis undoubtedly accounted for the large size of
the ductus arteriosus.

The aortic arch gave off the right common carotid, the left common
carotid, and the left subclavian. Immediately below the junction of the
ductus arteriosus with the descending aorta an abnormal right subclavian
arose.

The latter vessel, as is usual in this abnormality, passed to the right
behind the trachea and cesophagus to reach the first right rib,

of Great Britain and Ireland il

Discussion.

Dr J. CAMERON said that Mr Giilliatt brought the specimen for his

inspection, and he was much struck by the extraordinary features which
it presented. The trunk which sprang from the ventricular chamber
appeared to him at first to be a persistent truncus arteriosus, but a little
careful dissection exposed the vessel representing a very unusual form of
ascending aorta in which the blood-current was actually descending.
_ The specimen at first sight exhibited what looked like a common ven-
tricle, but on consulting Professor A. Keith he was informed that a chamber
representing the left ventricle would probably be found, On closer inspec-
tion this was shown to exist as a minute recess from the left auricle.

Dr R. J. GLADSTONE mentioned a very similar case, which he bad pre-

i viously shown at a meeting of the Anatomical Society, at King’s College.

In this specimen the left ventricle and ascending aorta were rudimentary.

It differed, however, from Mr Gilliatt’s specimen in the manner in which

the coronary arteries were filled. These received their blood from the rudi-

mentary left ventricle, and the ascending aorta above the coronary arteries

was obliterated; whereas in Mr Gilliatt’s specimen the ascending aorta,

_ though small, was patent, and the blood reached the coronary arteries by

coursing in a downward direction from the arch of the aorta, and there
was apparently no communication with the left ventricle.

He contrasted this case with those in which the right ventricle and
pulmonary artery are rudimentary or absent, and those in which there
is a common ventricular chamber due to absence of the interventricular
septum. In the latter, tricuspid, pulmonary, mitral, and aortic orifices are
all present, and open into the single chamber.

(4) Mr A. Macpnart exhibited a specimen showing an abnormal con-
dition of the maxillary antrum.

(5) Professor F. G. Parsons demonstrated the mode of termination of

the ligamenta dentata by means of a specimen which he said was typical

of eight cases he had observed. The last pair of ligamenta dentata was
situated between the exit of the twelfth thoracic and the first lumbar
nerves ; and instead of being shaped like the tooth of a saw, each consisted
of a narrow oblique band running downwards and outwards from the
beginning of the conus medullaris.

Professor Parsons suggested the possible value to surgeons of thus being

able to localise the twelfth thoracic and first lumbar nerves.

(6) Professor F. G. Parsons showed several specimens of hip-joints, in

which the ridge on the front of the neck of the femur coincided in position

12 Proceedings of the Anatomical Society

and direction with the outer limit of a groove transmitting a special band
of zonular fibres, which gripped the head of the femur just lateral to the
articular area. This band was deep to the main part of the capsule, from
which its fibres were not easily separable, though they often left a groove
in different parts of the neck of the femur.

As a result of piecing together the information gained from several
specimens, Professor Parsons believed that the band was attached anteriorly
to the lower part of the spiral line just in front of the attachment of the
pectineo-femoral ligament. From this it passed round the top and back of
the neck and, as it approached the lower part, was reflected towards the
acetabulum just behind the pectineo-femoral ligament.

It was suggested that the continuity of this zonular gripping band
below was interfered with by the presence of the ligamentum reflexum,
which is always to be seen, and represents the remains of the invagination
of the synovial membrane by the ligamentum teres.

(7) Dr J. CAMERON and Dr R. J. GLADSTONE gave a communication
which represented only a first instalment of a piece of work upon the
structural continuity of the cell-elements in the blastoderm during the
early stages of development. This work had for its chief object the
demonstration of the following points :—

I. It is the nuclei with their contained chromatic material, rather than
the cell-elements, which should be regarded as wnits of structure.

II. There is an organic continuity between the cell-elements of the
connective, epithelial, and other tissues of the body. —

Ill. This continwity is in most cases primary and not secondary.

IV. The so-called intercellular substance forms an essential part of a
continuous living tissue, which with its contained nuclei forms a plas-
modium. We prefer this name to “syncytium,” which signifies the fusion
of previously separate cell-elements.

In considering these points we should like to emphasise the importance
of distinguishing the protoplasm which immediately surrounds the nucleus,
commonly known as the endoplasm, and the protoplasm which lies external
to this, called the ectoplasm. The ectoplasm is in many tissues spoken of as
cement substance. We consider this material, however, to be living proto-
plasm, and it establishes an organic continuity between the cell-elements.
The cell-elements influence one another through the medium of this living
protoplasm, and there is thus a physiological continuity as well as a purely
material continuity. If this continuity is interrupted by artificial separa-
tion of the cell-elements, the unity of the organism is also broken up, as
has been shown by the experiments of Driesch and others on Hchinus larve,

Tet

of Great Britain and Ireland 18

which show that separated blastomeres, in the two- or four-celled stages, do
not produce embryos consisting of right or left halves, or quarters of a
whole embryo, but each separated blastomere produces a complete embryo,
though of smaller size than the normal. In the normal condition there is
an interaction of one cell upon another, which must be through this ecto-
plasmic layer, and this layer must therefore be regarded as an essential
part of the complete organism.

The blastomeres of the segmentary ovum of Echinus esculentus are
embedded in and held together by a zone of clear ectoplasm. The ecto-
plasmic bond of continuity between the cell-elements can also be demon-
strated in amphibian and avian ova.

In mammalian ova, e.g. the blastocyst stage of the mouse, the dividing
nuclei of the blastomeres are held together by a continuous protoplasmic
mass, the whole representing a plasmodium.

In the entypy stage of the mouse ovum the plasmodial nature of the
trophoblast, of the invaginated ectoderm, and of the covering layer of endo-
derm is still readily recognisable. We could detect no divisional line in
the partition of ectoplasm uniting any two adjacent cell-elements.

We further demonstrated the plasmodial structure of the placenta in
the guinea-pig, and find that the continuity of the cell-elements is primary
(plasmodium) and not secondary (syncytium).

In the first-day chick embryo continuity is present in all three layers of
the blastoderm. Protoplasmic bridges connect the mesoderm cell-elements ;
and where nuclear division is taking place, the daughter nuclei which
result from this are connected by protoplasmic bridges both with one
another and with the parent tissue.

(8) Mr W. M‘Apam Ecctes and Dr Finzi exhibited skiagrams to show
the value of a knowledge of “depth” in anatomy. In explaining these
skiagrams Mr M‘Adam Eccles made the following remarks :—

The teaching of applied anatomy is always interesting and most instruc-
tive. In surgery a knowledge of the “depth” of organs, structures, and
cavities from the surface is of great importance. Such a knowledge is not
often acquired during the period spent in the study of anatomy by the student.

The introduction of skiagraphy, and particularly in relation to gunshot
wounds, has rendered it even more important for the clinician fo possess
at any rate a fair knowledge of depth.

We (Dr Finzi and I) therefore venture to bring before you this afternoon
a short series of skiagrams illustrative of the desirability of such knowledge.

Let us take the skull. The depth of the pituitary fossa from the
bridge of the nose; the distance of the apex of the petrous portion of the

14 Proceedings of the Anatomical Society

temporal bone from the zygoma; the depth of the posterior part of the
orbit from the side of the skull; the relations of the sphenoidal and
maxillary antra to surface structures. All of these are good —
of the facts which require elucidation.

Then in the cervical region, the depth of the trachea and the ceso-
phagus from the front and the side of the skin covering the tissues of the
neck; the position of the cervical spinous processes in relation to the
surface of the back of the neck; and the depth of the trachea at the level
of the top of the manubrium sterni are all points of surgical interest.

The proportionate depth of the mediastina; the distance between the
side of the pericardium and the hilum of the lung with its bronchial
glands; the depth at which the ventral aspect of the pericardial sac lies
from the surface, again show the value of this knowledge.

In the abdomen the distance between the posterior aspect of the ventral
wall of the abdomen and the anterior surface of the lumbar vertebrae
is of considerable significance.

The knowledge of the depth of the lobes of the liver antero-posteriorly —
helps materially when searching for a deep-seated hepatic abscess.

The depth of the false and of the true pelvis is very different from the
general idea in the mind of the average medical practitioner.

In the upper limb, the depth of the musculospiral groove from the
surface, the thickness of the tissues covering the anterior aspect of the
elbow-joint, are points of interest.

In the lower limb, the distance between the outer surface of the great
trochanter, through the trochanter and the neck of the femur into the
bottom of the acetabular cavity, is of value when it is necessary to select
a screw for use in uniting the fragments in an intracapsular fracture of
the neck of the thigh bone.

The depth of the popliteal surface of the femur from the skin at the
back of the knee is known to few surgeons.

When considering depth, the anatomist, the radiographer, and the
practical surgeon should not only look at the question from its absolute
point of view, but also relatively to bony and other distinctive landmarks.

Thus, for instance, we may describe the femoral artery in Hunter's
canal as being internal to the femur and two and a half inches on the
average from the skin surface of the anterior aspect of the thigh, but we
may also locate it as being one-third the distance from the front in an
antero-posterior section of the limb.

A knowledge of this fact will at once make clear that the artery in an
amputation by antero-posterior flaps in the middle of the thigh would be
found in the anterior flap.

7c eee) _. ae
- eT) <a ae
oo) ee ‘

:

ae ee

= of Great Britain and Ireland 15

(9) Professor F. Woop JONES was not present to give his paper upon

the homologies between mammalian and chelonian types of genitalia, and

this was accepted as read.

(10) The paper upon the rotation of the intestine by Professor J. E. S.
Frazer and Dr C. H. Ropsins was postponed until the next meeting of
the Society.

JUNE 1915

MEETING (in place of the usual Summer Meeting) held on Friday, June 4,
1915, at St Mary’s Hospital Medical School; the President, Professor
Howden, in the chair.

Twelve members and twenty visitors were present.

(1) Mr T. YearEs gave the following demonstration of an early ferret
heart, the features of which were displayed by lantern slides of reconstruc-
tion models :—

The heart demonstrated is one of a ferret embryo removed from the
mother fourteen days after coitus. It is curved on its long axis, so as to
present a convexity directed towards the head end of the embryo.

At this convexity the myoepicardium is infolded to form the atrio-
ventricular junction which subdivides the curved tube into a shorter dorsal
ventricular limb and a longer ventral atrial one. The latter limb is further
subdivided by the venous valves into sinus and atrium. The ventricular
limb is single at its arterial extremity, whilst on the other hand the atrial
limb is bifurcated at its venous end. Briefly, the myoepicardial tube is a
curved one, single at its arterial but bifurcated at its venous end.

The myoepicardium is reflected along the attachment of the dorsal
mesocardium and around the arterial and venous orifices on to the peri-
cardium. As the dorsal mesocardium is attached, not only to the undivided
part of the heart tube but also to its two limbs, it, like the myoepicardial
tube, is single at its arterial but bifurcated at its venous extremity.

The bilateral origin of the heart is made evident by the existence of
remnants of the primitive cardiac septum, and also by the fact that the
endothelial heart has not yet fused into a single tube.

An interesting point connected with this heart may be mentioned. We
find projecting into the arterial orifice between the endothelial aorte the
apex of a large prominent ventral pouch of the pharynx. The apex of
this pouch appears, from its relation to the second visceral cleft, to be the
median thyroid. As the arterial orifice has as yet undergone no reversal,
whilst the ventral wall of the pericardial ccelom is almost completely

16 Proceedings of the Anatomical Society

reversed it appears probable that when the arterial orifice undergoes
reversal most of the ventral pharyngeal pouch will disappear and be
replaced by a prominence projecting from the floor of the foregut towards
its cavity. On the summit of this prominence the median thyroid (apical
part of the pharyngeal pouch) will open. If this interpretation is correct,
then the apex of the pouch is the median thyroid, whilst the remainder of
the pouch represents the tuberculum impar.

The chief conclusions arrived at after the most careful study of this
heart are :—

1. The transverse part of the ecelom alone becomes the pericardium.

2. There is no folding in of the splanchnopleuric folds, as usually
described, to form the floor of the foregut.

3. The tuberculum impar is a result of the reversal of the pericardial
(transverse) coelom.

4. The walls of the transverse ccelom (pericardium) reverse at different
rates. The ventral wall reverses most quickly, whilst the caudal wall is
the last to assume its definite position. .

5. Previous to the development of the ventricular loop the heart
presents a loop, the junction of the limbs of which corresponds to the atrio-
ventricular canal. ;

It may be mentioned that Koelliker has figured sections of a rabbit -
embryo, similar to those from which this heart was reconstructed, but he
has not given a detailed account of the heart at this stage. It appears
from his sections that the early development of the heart in the Rodentia is
similar to that in the Carnivora. Born makes no mention of such stages
in the rabbit.

Discussion.

Professor ARTHUR KEITH dwelt upon the great difficulty of interpreting
the early stages of the heart. He suggested that the terms “dorsal” and
“ventral” should be less freely used in describing an organ the aspects of
which undergo so great a series of changes in development.

(2) In the absence of Mr M. G. O’Matiey, Dr JoHN CAMERON demon-
strated a specimen showing a persistent left superior vena cava.

The principal features of the specimen were as follows :—

A well-developed cross-branch connecting jugular veins about 1} inch
below their junction with subclavian veins. ‘The inferior thyroid veins
end in a single trunk which joins the cross-branch about ? inch from its
right extremity. A little to the left of where it is joined by this thyroid
branch the cross-communication is much narrowed. The narrowing is local.

The left superior vena cava is little more than half the size of the right.

eS

of Great Britain and Ireland 17

ee

——

Tt bears the usual relation to the root of the left lung, and the phrenic

nerve lies along its left side.

The left superior intercostal vein joins the left superior vena cava
about 1 inch below the cross-branch. The vena azygos major joins the
right superior vena cava at exactly the same level. The similarity in
position and direction of the vena azygos major and the left superior
intercostal vein is rather striking.

A small vein accompanying the phrenic nerve joins the left superior
vena cava close to and a little to the right of the termination of the left
superior intercostal. This is apparently the left superior phrenic vein.

The left superior vena cava is joined by the great or left cardiac vein
to form the coronary sinus. A valve of two segments guards the mouth
of the great cardiac vein. The opening of the middle cardiac vein into the
coronary sinus shows a similar valve.

There is no trace of a Thebesian valve.

The thymic veins do not join the cross-branch. They join the left superior
vena cava close to its junction with the cross-branch and below the latter.

(3) In the absence of Professor KENELM H. Dicsy, Professor ARTHUR
Keira explained a method of preparing dry specimens.

Wet specimens preserve the original appearances of the fresh tissues
with great faithfulness, but they have this one disadvantage, that they
are not very readily handled. For a student commencing to learn anatomy
it would be helpful if he could handle and feel an organ as freely as he can
handle the bones. Tissues which have simply been allowed to dry are of
little use owing to the great and unequal shrinkage which has occurred.

The nine dry specimens I am showing illustrate a method consisting of
four stages :— :

1. Fixation by strong formalin.

2. Gradual dehydration with acetone.

3. Impregnation with celluloid dissolved in acetone.

4. Removal of excess of solution while the specimen hardens in the air.

A few further details may be added. The fixation should be performed
im situ by injection into an artery. The stronger the solution of formalin
the better. The dehydration should be slow, the specimen remaining
in each of at least two strengths before being passed into pure acetone.
The passage through gradually increasing concentrations of celluloid in
acetone should be even slower. The last solution should be as strong
as possible. Finally the organ is removed, wiped, and straightened, or
arranged in its correct position if necessary. There is ample time, as
the tissues take half an hour or more to harden.

18 Proceedings of the Anatomical Society

The specimens shown are experimental ones, and could be considerably
improved upon, as some of them were imperfectly fixed and were de-
hydrated too rapidly. It will be seen that if a little excess of celluloid
solution be allowed to dry on the tissue, the specimen can be coloured. The
method is economical, for the excess of celluloid can be used again, and the
acetone could, I expect, be recovered by distillation from solutions which
have become too diluted. I should also like to draw attention to the use
of sheet celluloid for mounting specimens upon. The sheet is transparent,
is easily cut by scissors or pierced by a pin; and specimens can be attached
by catgut or made to adhere by celluloid solution.

(4) Professor ArTHUR KEITH also gave an abstract of a paper by Pro-
fessor KENELM H. Dicpy upon the measurement of diaphysial growth. The
method employed by Professor Digby consisted in estimating the length of
the bone upon either side of the foramen of the nutrient artery. The assump-
tion was made that the principal nutrient artery supplied, in the original
condition, the primary ossific centre of the shaft, and that therefore the
growth of the bone in either direction could be directly measured. —

Professor Woop JoNEs and Professor J. E. S. FRazER pointed out that
the method was correct only in a general sense of the main direction of
growth; since primarily the nutrient arteries were serial and plexiform
vessels, and the permanent one was not necessarily the one supplying the
region of the primary centre of ossification.

(5) Professor J. E. 8S. Frazer demonstrated a series of reconstruction
models prepared by himself and Dr R. H. Rosstns to illustrate factors
concerned in the rotation of the intestine. .

Starting from the time when the intestinal tube is in the median sagittal
plane, the changes it undergoes in position to reach the adult state may be
divided into three stages: the first stage lasts until the gut returns to the
abdomen from the umbilical sac, the second from the return till the caecum
reaches the posterior abdominal wall, and the third from this on.

The essential character of the second stage is the presence of the
proximal limb of the loop to the right of the middle line. With this goes
fixation of the base of the loop, by the thick dorsal mesentery of the
duodenum proximally, and. by a thick “retention band” which runs from
this region to the “hind-gut” distally: this last band makes a “colic
angle” in the tube where the distal limb of the loop turns to the umbilicus,
and, by holding this angle, relatively approximates it to the duodenum. The
duodenum is curved out on its attachment by the growth of the pancreas,
and is not concerned in the causation of rotation. The turning to the
right of the proximal limb is probably due to the rapid descent of the

of Great Britain and Ireland 19

liver and the large new vitello-umbilical venous channel running up from
left to right. Many coils are formed on the proximal limb towards the
end of the second and beginning of the third month, but not on the distal
limb, and the intra-abdominal colon and its mesocolon form a median
septum in the cavity, with stomach and omental bursa on the left, and
duodeno-umbilical coil on its right, between it and the liver.

The second stage is that of real rotation. The passage of the umbilical
gut to the belly is due to pressure on the sac, relatively increased owing
to fall of internal pressure, consequent mainly on reduction of liver mass.
Return cannot take place en masse, and the large size of the cecum
causes it to remain in the sac to the last, so that the proximal limb is
the first to slip back: it enters the abdomen to the right of the mesocolic
septum, which is bowed out to the left by it, lifting up the bursa and
stomach, and the coils fill both sides of the lower part of the belly. In
doing this they have passed below the level of the stem of the distal
limb, which is still in the sac, and of the mesenteric vessels, which also
remain there owing to their close relation to the distal limb. So, when
finally the distal limb returns, it finds itself lying above the mass of coils,
the czcum not reaching to the front limit of this mass, but lying between
it and the liver. The growth of the coils proceeds rapidly, and the caecum
is pressed back from its position between them and the liver, thus coming
to lie transversely behind the coils, across their mesentery. It comes into
relation with the back wall just above the crest of the ilium. Thus there
is rotation through half a circle affecting the free loop only.

The colon and small bowel are now in their proper planes, and the third
stage is made up of the extensions and fixations in these planes which,
lasting till after birth, lead to the adult disposition. The place of the
original colic angle remains at or near the middle line: to its left the
abdominal mesocolon is laid back in contact with the omental bursa and
back wall, and will extend upwards and to the left: to its right the
mesocolon of the umbilical colon is laid back against the duodenum and
back wall, and will extend upwards and to the right. As these areas
of mesocolon extend they become fixed, and this is the only fixation which
the originally median mesentery undergoes.

Professor ArTHUR KEITH pointed out that the suspensory mechanism
of the colic angle persisted in the adult rabbit. He expressed the opinion
that vital growth rather than mechanical factors influenced the rotation
of the intestines.

(6) Professor F. Woop Jones demonstrated the gross anatomy of the
genitalia of Galeopithecus volans. The curious circum-anal pouch was

20 Anatomical Society of Great Britain and Ireland

assumed to be the persistent hinder portion of the cloaca, and the import-
ance of this type lay in its fixing the site of the posterior cloacal margin,
which becomes obliterated in most other Eutherian mammals. The affinities
of this type of genitalia were then discussed, and it was argued that by far
the nearest match to the adult condition of Galeopithecuws was to be found in
the embryonic stages of many bats, and even in the adults of some species.

(7) Dr R. J. GLADSTONE showed two examples of right aortic arch,
one of which presented a persistent left duct of Cuvier. The two were
discovered in still-born infants, but there was no apparent association
between the anomaly and the cause of death. In both cases the ascending
aorta lay to the right of the pulmonary artery, the converse of the con-
dition which is present in transposition. |

In specimen A, the arch of the aorta gave off three branches, in order
from left to right: (1) innominate (left); (2) right common carotid; (3) right
subclavian. A special character of this specimen was the opening into
the commencement of the subclavian artery of a vessel representing the

“ductus arteriosus,’ which sprang from the origin of the left pulmonary ©

artery. There was no “ductus arteriosus” on the right side. The left

recurrent laryngeal nerve hooked round the subclavian artery of the™

same side lateral to the “ductus arteriosus” (sixth arch). The right re-
current laryngeal nerve wound round the aortic arch. The left duct of
Cuvier persisted, and had the usual relations. It was about half the
size of the right superior vena cava.

Specimen B. In this case the right aortic ‘ol gave off four branches:
(1) left common carotid ; (2) right common carotid; (3) right subclavian ;
(4) left subclavian. The left subclavian artery whan viewed from the
front appeared to spring from the pulmonary artery, as there was a large
communication between the two. This represented the “ductus arteriosus ”
or dorsal portion of the sixth arch. The first part of the left subclavian
artery was thus derived from the distal part of the left dorsal aorta,
whereas the first part of the left subclavian artery in is sae: B was
derived from the fourth left arterial arch.

Dr GLADSTONE also showed a linear reconstruction of the main arteries
of a 17-mm. human embryo, proving that a very considerable portion
of the right dorsal aorta between the fourth right arterial arch and the
seventh segmental artery is utilised in the formation of the normal right
subclavian artery, and inferred that a similar portion of the left dorsal
aorta must have contributed to the formation of the left subclavian artery
in specimen A.

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