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THE

liWi AND BILIARY SYf': 1

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THE LIVER, SPLEEN, PANCREAS,
PERITONEAL RELATIONS, AND
BILIARY SYSTEM IN MONO-
TREMES AND MARSUPIALS.

WILLIAM COLIN MACKENZIE,

M.D., F.R.CS., F.R.S. (Edin.).

Member of the Council of the Anatomical Society
of Great Britain and Ireland.

Illustrated ivith over 70 Original Figures.

From the Australian Institute of Anatomical Research,

Melbourne.

All proceeds from the sale of this work will be

devoted to the advancement of Medical Research in

the Commonwealth of Australia.

CRITCHLEY PARKER HI
AUSTRALIA,

1918.

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INTRODUCTION.

Like the previous work, dealing with the gastro-
intestinal tract in Monotremes and Marsupials, the
present volume, though structural in character, has been
written from the point of view of physiology, i.e., func-
tion This also applies to the illustrations of the dissec-
tions. By a study of the two above-mentioned orders
light is thrown on the nature of the primitive liver from
which the human liver has been evolved; in the Platypus
we have a multilobed liver, whilst some varieties of the
Victorian Wombat may have a liver practically resemb-
ling the human in type. In this maimer, i.e., viewed from
the comparative standpoint, anomalies of the human
liver, which are not infrequent, become intelligible. As the
function of the hepatic cells are multiple, and as these
functions must bear an evolutionary sequence one to
another, it is possible that in the near future the classi-
fication of diseases of the liver will be based on that
sequence. Thus it is conceivable that there may be a loss
of one, or some, but not necessarily all, of the functions
of the hepatic cell. Again, the question might well arise
— Does one portion of the human liver or spleen perform
functions differing from those of some other? The pos-
sible differentiation in their action on cells of vital stains,
for the interpretation of which we are so much indebted
to Professor Herbert Evans of the University of Cali-
fornia, holds out some promise of results in this direction.

If we compare the "highest" form of Australian rep-
tile with the "lowest" mammal, the Platypus, three dis-
tinctive features stand out in the latter as compared with
the former. These are — (a) the presence of a diaphragm

forming a complete septum between the thorax and abdo-
men, (b) great development of spleen, (c) development
of great omentum. Great omental development is prim-
arily correlated to great splenic development. With the
assumption of the erect position in man, the great omen-
tum is a factor in supporting the transverse colon. A
human omentum that was free of transverse colon would
be one liable to torsion, and this would be more likely on
the left than on the right side.

In these studies variability is shown as regards the
position of entrance of bile ducts relative to the pyloric
sphincter and duodeno-intestinal junction, and also in the
relation of the pancreatic to the bile duct ; so that prob-
lems referring to digestive function are raised. In a
typical section of the human pancreas the areas of Lan-
gerhans may be difficult to define; but in histological
sections of the pancreas of, e.g., the Wombat or Tas-
manian Devil, numerous areas are to be met with.

Many other functional problems might be mentioned,
but these few examples are cited to show what a rich
field is open to the medical research scholar.

In conclusion, the writer wishes to thank the Presi-
dent and Council of the Royal College of Surgeons of
England, and also Professor Arthur Keith, for facilities
accorded him while working in the laboratories of the
Hunterian Museum; Professor Sir Baldwin Spencer and
Mr. Kershaw for the privilege of conducting researches
at the National Museum in Melbourne; the Editor of the
"Journal of Anatomy'1 for permission to reprint his
article on the Spleen in Vol. LI. of that journal; his
cousin, Major Charles Mackay, for valuable help in the
preparation of the dissections; and also Mr. Finerty, of
London, and Miss Esther Paterson and Mr. Victor Cobb,
of Melbourne, for the excellent illustrations.

VI.

COXTKNTS.

MONOTREMATA.

Pa«

The Liver, Pancreas, <iall Bladder, Ducts and Peritonea] relation:- in
Platypus ( Ornithorhynchus Anatinus), and Echidna (Echidna

Aculeata ) 1

MAiRSUPIALIA.

The Liver. Pancreas, Gall Bladder, Duets and Peritoneal relations in

Macropus (Kangaroos and Wallabies) 28

The Liver, Pancreas, Gall Bladder, Ducts and Peritoneal relations in

Wombat ( Pliascolomys I -Mi

The Liver. Pancreas, (Jail Bladder, Dint- and Peritoneal relations in

Koala ( Phascolarctus Cinereus) til

The Liver. Pancreas, Gall Bladder, Ducts and Peritoneal relations in

Tasmanian Devil (Sarcophilus Ursinus) 80

The Liver of Native Australian tat (Dasyurus Viverrinus ) 97

The Liver of Bandicoot ( Peramelidae) 101

The Liver. Pancreas. Gall Bladder, Ducts and Peritoneal relations of

Australian Phalangers (Trichosurus and Pseudochirus) 1 04

The Liver of American Opossum (Didelphis Marsupialis) 1'20

i >bservations . . 122

MONOTREMATA.

The Spleen and Peritoneal relations in Platypus 135

The Spleen and Peritoneal relations in Echidna 137

MARSUPIALIA.

The Spleen and Peritoneal relations in Tasmanian Devil 139

The Spleen and Peritoneal relations in Koala 140

The Spleen and Peritoneal relations in .Macropus (Kangaroo- and Walla-
bies) 141

The Spleen and Peritoneal relations in True Phalangers 143

The Spleen and Peritoneal relations in Wombat 14t!

Interpretation of Structural Anatomy loll

VI 1.

LIST OF [ILLUSTRATIONS.

Page

Mammalian liver. Genera] Plan Diaphragmatic Surface xiii.

Mammalian Liver, Genera] Plan Viscera] Surface xv.

Diaphragmatic Surface of Liver, Platypus 4

Diaphragmatic Surface <>t' Liver, Echidna 4

The Multilobed Liver of Platypus, Visceral Surface 6

Visceral Surface of Liver, Echidna 9

'I he Gastro-Intestinal Tract and Peritoneal Relations, Platypus II

Biliary and Porta] Systems of Liver, Platypus 13

Stomach Duodenum and Ducts, Platypus 16

Pancreas and Pancreatic Ducts, Platypus 18

Biliary and Portal Systems of Liver, Echidna 20

The Pancreas in Echidna 24

Stomach and Liver in Echidna 20

Diaphragmatic Surface of fiver, Kangaroo 29

Viscera] Surface of Liver, Kangaroo 32

Biliary and Portal Systems Liver, Kangaroo 36

The Gastrointestinal Tract in Kangaroo 38

Diaphragmatic Surface of Liver, Wombat (Specimen A) 41

Diaphragmatic Surface of Liver, Wombat (Specimens BvC.D.) 43

Visceral Surface of Liver, Wombat (Specimen A) 45

Visceral Surface of Liver, Wombat ( Specimen B) 48

Visceral Surface of Liver, Wombat (Specimen iC) 50

Liver, Stomach and Spleen, Wombat (Specimen D) 52

Visceral Surface of Liver, Wombat (Specimen D, E) 54

Biliary and Portal Systems, Liver, Wombat 50

Diaphragmatic Surface of Liver, Wombat (Specimen E, F) 60

Visceral Surface of Liver, Wombat (Specimen F) 03

The Gastro-Intestinal Tract of Wombat 65

Diaphragmatic Surface of Liver, Koala 68

Visceral Surface of Liver, Koala 70

Biliary and Portal Systems, Liver, Koala 74

The Gastro-Intestinal Tract in Koala 77

Diaphragmatic Surface of Liver, Tasmanian Devil (Specimen 1) .. .. 81

Diaphragmatic Surface of Liver, Tasmanian Devil (Specimen 2) .. .. 83

Visceral Surface of Liver, Tasmanian Devil (Specimen 1) 8e"

Visceral Surface of Liver, Tasmanian Devil (Specimen 2) 88

Biliary and Portal Systems. Liver. Tasmanian Devil 90

The Gastro-Intestinal Tract, Tasmanian Devil !)4

Diaphragmatic and Visceral Surface of Liver, Native Cat 98

Diaphragmatic Surface of Liver. American Opossum 100

Diaphragmatic Surface of Liver, Bandicoot 100

The Gastro-Intestinal Tract of Bandicoot 102

The Gastro-Intestinal Tract of American Opossum 102

Diaphragmatic Surface of Liver, Trichosurus 105

Diaphragmatic Surface of Liver, Pseudochirus 105

Visceral Surface of Liver, Trichosurus 108

Visceral Surface of Liver, Pseudochirus 1 10

Miliary and Portal Systems, Liver, Phalanger 113

Gastro-Intestinal Tract, Spleen, Pancreas, Trichosurus llii

The Gastro-Intestinal Tract, Pseudochirus US

Liver of Gorilla 128

The Peritoneal Relation of Spleen in Platypus 130

The Peritoneal Relations of Spleen in Echidna . .. 13d

Spleen in Koala 14-

Sp'eens of Macropodidae 142

Visceral Surface of Spleen, Wombat Its

Surface of Spleen, Phalangers 154

Spleen, Young Orang 154

Spleen, Young Baboon 154

Spleens, Human Foetus 154

Spleens of Agama and Lygosoma 154

ix.

LIVER, PANCREAS, PERITONEAL RELATIONS

AND BILIARY SYSTEM IN MONOTREMES

AND MARSUPIALS.

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THE LIVER IN MONOTREMATA.

PLATYPUS AND ECHIDNA,

The liver, as in the human foetus, stretches across the
upper abdomen, being placed in the epigastric and right
and left hypochondriac regions. In the human adult it
lies in the epigastric and right hypochondriac regions
only. Bv means of the right lobe and the lobus caudatus
the liver is prolonged along the right dorsal abdominal
wall reaching as low as the 11th rib.

Diaphragmatic Surface. — - (a) Platypus. — On this
aspect of the liver an immediate division into three parts
is evident, aTz. mesial or cystic (ventral), right and left
lateral (dorsal).

Dextrallv and distinct from the right lobe we may see
a portion of the lobus caudatus. The mesial or cystic
lobe is separated from these two latter b}T means of a
coronal or transverse lissure and the lateral lobes are
separated by an oblique fissure running downwards and
to the left. The oblique fissure is not prolonged as far
ventrally as the coronal fissure. There is usually 1 cm.
of hepatic tissue between the two. If it were so pro-
longed it would reach the exit of the inf. v. cava. At
the dorsal extremity of the fissure is a gap; here the
oesophagus passes to the stomach and in relation also to
the gap is the small lesser curve of the latter. Towards
the left aspect dorsally of the right lateral lobe a small
fissure is seen about 1 cm. long — though more marked in
some than in others — and serving to define a portion of

l B

PLATYPUS AND ECHIDNA.

liver between it and the oblique fissure which is the
spigelian lobe. Passing from the ventral extremity of the
small fissure to the vena cava, so that it runs between the
right lateral and spigelian lobes, is a membrane 2 cm.
long attached above to the diaphragm. The fissure and
membrane correspond to the hepatic relationship of the
inf. vena cava, and the spigelian lobe is seen to be part
of the right lateral lobe. The inf. v. cava, is not seen on
this aspect. It lies behind the junction of the right
lateral and spigelian lobes and the length from entrance
to exit is 3.5 cm. Its exit corresponds to practically the
middle of the coronal fissure. Passing backwards from
about the middle of the ventral margin of the cystic lobe
we may see a fissure 2 cm. long through which and
especially if distended the gall bladder projects. More
often a gap is seen on the ventral edge enabling the gull
bladder to be seen on this aspect. It is 1 cm. long and .75
cm. wide, and from the gap we rind passing dorsally two
fissures — one mesial corresponding to the suspensory
ligament and the other oblique and dextral in which the
gall bladder projects. Between these two fissures we see
on this aspect an early indication of the lobus quadratus
so well defined in the human liver. It is about .75 cm.
laterally.

In the middle of the mesial lobe we see the longitudi-
nal or suspensory ligament — a triangular fold attached
above to the muscular and tendinous portion of the dia-
phragm. It passes forward from the coronal fissure to the
gall bladder cleft or fissure and measures 3 cm. on its ven-
tral aspect. It represents part of the original ventral
mesogaster. By its means and the cleft the mesial lobe is
divided into right and left portions. In addition to the
fold between the right lateral and spigelian lobes two fine
peritoneal folds are noted from the dorsal margins of
the right and left cystic lobes to the diaphragm. At the

Bl 2

PLATYPUS AM) ECHIDNA.

exit of* the vena cava, meet the peritoneal folds connect-
ing liver to diaphragm. From this point also where it is
continuous with the suspensory ligament we see a mem-
brane attached above to the diaphragm and curving down
on the inner side of the left lateral lobe. At the dorsal
curved portion of the oblique fissure it is continuous
with the gastro-hepatic omentum. In a large male Platy-
pus the lateral (dexiro-sinistral) measurement of the
liver was 13 cm. and dorso-ventral measurement was 9
cm. Laterally, cystic was 10 cm., left lateral was 7 cm.,
right lateral including spigelian was 8 cm.

(b) Echidna.— Here we distinguish the same divi-
sions as in the Platypus, viz. mesial or cystic in front sep-
arated into a large right and smaller left portions by the
suspensory ligament, and dorsally the right and left lat-
eral lobes separated from the former by the coronal fis-
sure. The cystic lobes form less of the anterior margin of
the liver than in Platypus. The suspensory ligament runs
obliquely backwards and to the right (not mesially) from
the ventral border to the coronal fissure (inf. v. cava.).
Its length is 4.5 cm. and it is attached above to the mus-
cular and tendinous part of the diaphragm. There is
no gall bladder fissure as in the Platypus, i.e. the gall
bladder does not project on the diaphragmatic surface.
In only one of a series of eight specimens was there a
thinning of the liver substance over the gall bladder with
a slight indentation on the ventral margin. This was
to the right of the suspensory ligament. Though the
coronal fissure may completely separate the cystic from
the lateral lobes yet we frequently see evidence of fusion
dorsally between the right lateral and right cystic and left
lateral with the left cystic lobes, and especially the latter.
Thus we have a right and left coronal fissure and the
left coronal may be 1.25 cm. from the inf. v. cava. There
is a more complete differentiation of the spigelian from

Diaphragmatic Surface of Liver. Platypus.

Diaphragmatic Surface of Liver. Echidna.

B Gall Bladder Cleft, I.M Left Mesial or Cystic Lobe. RM Right
Mesial or Cystic Lobe, V Inf. Vena Cava. C Caudate Lobe.
S Spigelian Lobe. L Left Lateral Lobe, R Right Lateral Lobe,
A Coronal Fissure (right and left lateral), 1) Oblique Fissure.
E (iap for ( (esophagus. F Fissure on right lateral lobe.

Dotted Lines represent Attachments to Diaphragm.

PLATYPUS AM) ECHIDNA.

right lateral — a dejn'ession running between the two
containing the inf. v. cava which is exposed in its hepatic
relation on this aspect and not hidden as in the Platypus ;
occasionally one sees a thin bridge of hepatic tissue over
the inf. v. cava anteriorally. Posteriorally at a pocket
between the spigelian and caudate lobes the inf. v. cava
comes into relation with the liver. Its exit corresponds
to the junction of coronal and oblique fissure and suspen-
sory ligament. The oblique fissure separating the spi-
gelian and left lateral lobes is complete to the coronal
fissure, and we see that the spigelian belongs to the right
and not to the left lateral lobe. The lateral lobes arc
almost equal in size and measure approximately 7 cm.
dorso-ventrallv and 8 cm. laterally, while in the cystic the
left laterally is 3 cm. and the right 7 cm.

Diaphragmatic Relations. — In addition to the suspen-
sory fold a small fold may be occasionally seen passing
from the inner and back of the right cystic lobe to the
diaphragm. Compared with the Platypus the dorsal
margins of the cystic lobes are free, being unattached to
the diaphragm. As in the Platypus a fold is noted be-
tween the right lateral and spigelian lobes attached above
to the muscular and tendinous portions of the diaphragm
and traced to the wall of the inf. v. cava. The inner and
back part of the left lateral lobe is concave and a gap is
present between it and the spigelian lobes. Here the
oesophagus passes on to the stomach.

A peritoneal fold is noted — attached above to the dia-
phragm— at the inner and back part of the left lateral
lobe, leaving internally a small triangular area between
the fold and the oblique fissure. It passes to the ventral
surface with the oesophagus and becomes continuous with
the gastro-hepatic omentum. About the exit of the vena
cava between the two coronal fissures it is continuous with
the suspensory ligament.

The Multilcvbeo Liver of Platypus. Visceral Surface.

ST Stomach, V Inf. Vena Cava. K. Kidney, A Adrenal. E Pylorus,
L Left Lateral Lobe, R Right Lateral Lobe, C Caudate Lobe.
S Spigelian Lobe, KM Right Mesial or Cystic Lobe. LM Left
Mesial or Cystic Lobe. I) Diaphragm.

PLATYPUS AND ECHIDNA.

Visceral Surface. — (a) Platypus.— The three main
divisions are seen to be present, viz., mesial or cystic
separated by the gall bladder into a right and
left portion, and the right and left lateral Lobes. The
under surface of the left lateral is free from projection,
but from the right lateral we have projecting the lobus
spigelii and dextrally the larger free caudate lobe. The
caudate lobe is hollowed below, forming with the right
lobe a concavity for the reception of the convex upper
part of the kidney. Its ventral surface is related to the
mesoduodennm, pancreas, and colon. It measures 4.5 cm.
laterally and 3 cm. dorso-ventrally. The spigelian lobe is
seen to lie below the under surface of the left lobe, from
which it is free however and projects into the lesser
peritoneal sac. It measures 2.3 cm. laterally and 2 cm.
in greatest width. On its inner or sinistral surface is a
groove corresponding to the pyloric knob and commence-
ment of the duodenum, and ventral ly it is related to the
duodenum as far out as the duct. The right lateral lobe
like the caudate has three surfaces — diaphragmatic — -
lower or caudal to receive with the caudate the upper pole
of the right kidney — and the visceral. This latter is re-
lated to the duodenum which is lodged in a depression
with a ridge internally. It curves along the outer part of
the right cystic — right lateral - and occasionally
the caudate. The gall bladder is placed on the
under surface of the mesial or cystic lobe. Where
a fissure exists on the diaphragmatic surface we
have on this aspect also a fissure lodging the gall blad-
der, and the cystic lobes on each side are of equal size.
Usually however the gall bladder is lodged in a fossa
which encroaches more on the visceral surface of the right
cystic than the left cystic lobe. The cystic duct may not
be related to the cystic lobe — the gall bladder extending
to the coronal fissure which separates the right and left

PLATYPUS AND ECHIDNA.

lateral from the cystic lobes. Or we may have the dorsal
part of the fossa hading into a fissure lodging the duct
which is partly between the right and left cystic lobes
and partly in the portal interval. The portal interval
lies between the narrow inner extremities of the right and
left lateral lobes where the coronal and cystic fissures
meet. Here the hepatic ducts join the cystic, and it may
almost he regarded as the central point of the liver: be-
tween the lobus spigellii and the caudate lobe is a depres-
sion 1.75 cm. long, often fissured dorsally.

Here we have passing eaudally the portal vein, com-
mon duet, and hepatic artery — the vein lying dorsally as
in the human liver. The vena cava passes obliquely up and
to the left in the liver substance behind the junction of
the right lateral and spigelian lobes to the diaphragmatic
surface. The membrane which we described curving
round witli the oesophagus from the diaphragmatic sur-
face is continued as the gastro-hepatic omentum which is
traced on the inner or right part of the visceral surface of
the left lateral lobe to the portal interval. This repre-
sents the hepatic attachment of the lesser omentum. It
is worthy of note that on the left lobe towards the outer
boundary an oblique depression may be seen probably
indicating the remains of a fissure between two divisions
of the left lateral lobe, and a fissure or depression is
sometimes noted towards the inner side of this lobe also.

(b) Echidna. — The mesial, right and left lateral, spi-
gelian, and caudate lobes, are defined — as in the Platypus.
The suspensory ligament is traced over the ventral edge
from the diaphragmatic surface. There may or may not
be a fissure where it crosses the ventral edge. It runs on
the ventral surface for about .75 cm. and usually termi-
nates in a fissure. Between the fundus of the gall bladder
and the ligament there is usually a small area of hepatic

Visceral Surface of Liver. Echidna.

B Gall Bladder, R Suspensory Ligament. LM Left Mesial or Cystic
Lobe, RM Right Mesial, or Cystic Lobe, R Right Lateral Lobe,
L Left Lateral Lobe, V Inf. Vena Cava, C Caudate Lobe.
S Spigelian Lobe.

PLATYPUS AND ECHIDNA.

tissue .25 to .5 cm. wide representing the lobus quadratics
of the human liver. We have not as in the Platypus the
projection of the spigelian lobe ventral to the left lateral
lobe. The inner extremity of the left lateral lobe (i.e. at
portal interval) is almost pointed. There is a well defined
lobus caudatus ventral to the right lateral lobe and more
prominent than in the Platypus, so that the greater part
of the latter is hidden on this surface, only the upper and
outer angle being usually seen. As in the Platypus the
caudate lobe has three surfaces — dorsal — ventral for
duodenum — and lower or caudal hollowed for the upper
pole of the right kidney. In the Echidna more of the
concavity for the kidney is formed by the caudate lobe
than in the Platypus, in which, half is usually formed by
the right lateral and half by the caudate lobe. The right
lateral is the larger of the two however, measuring later-
ally 8 cm. and dorso-ventrally (> cm., while the caudate
measured 5 cm. in each direction. On this surface the
right and left portions of the coronal fissure are con-
tinued to the portal interval. Here the spigelian lobe is
relatively a much smaller structure than in the Platypus
and a partial depression or groove between the spigelian
and caudate lobes over which passes the portal vein —
artery — and common duct constitutes the only distinction
between them. The spigelian lobe appears as a somewhat
pointed prolongation to the left of the caudate and passes
behind the lesser omentum, being contained in the lesser
sac and related to the lesser curve of the stomach. In a
large male specimen its length was 3 cm. and greatest
width 1.75 cm. Passing down in the groove on the dextral
extremity of the lateral lobe between it and the spigelian
lobe is the oesophagus. On the diaphragmatic surface we
described a fold continuous at the inf. v. cava with the
suspensory ligament passing vertically at the groove for
the oesophagus on the inner margin of the left lateral

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Thk Gastrointestinal Tract and Peritoneal Relations

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PLATYPUS AND ECHIDNA.

lobe. This becomes continuous with the hepatic attach-
ment of the gastro-hepatic omentum which runs along
the ventral surfaces of the narrow inner part of the left
lateral lobe to the portal interval. On the inner side of
the left lateral lobe a small lobe may be separated off by
a fissure. On the caudal or renal aspect the inf. v. cava
can be seen passing between the spigelian and caudate
lobes but is not visible in its hepatic relation from this
aspect. The left lateral measures 5-6 cm. laterally and
the complete cystic 6 cm. The ventral surface of the
left cystic and left lateral lobes are related to the bodv
of the stomach. The duodenum is related to the right
cystic, right lateral, and caudate lobes. The liver is
larger in the Echidna than in the Platypus, its greatest
lateral measurement being 16 cm. and dorso- ventral 10-12
cm., whilst in the Platypus the length laterally may reach
13 cm. and dorso-ventrally 8-9 cm.

Gall Bladder and Ducts,

(a) Platypus.- — The (Jail Bladder is smaller than in
the Echidna and projects at the ventral margin of the
mesial or cystic lobe. It is usually empty and collapsed,
unlike that of Echidna, and measures 2 cm. long and 1-1.5
cm. wide ventrally. It is a somewhat pear-shaped struc-
ture presenting a fundus or ventral extremity and body.
Though the fundus is mobile the gall bladder is really a
fixed organ, being invested by peritoneum on the sides
and under or ventral surface only. At the exit of the
cystic duct it usually narrows somewhat, so that a neck
may be described. On the other hand the duct may pass
abruptly from the body.

Cystic JHtcf.- -This measures 1 cm. long. It may lie
partly between the right and left portions of the cystic
or mesial lobe and partly in the portal interval, or it may

1-2

Biliary and Portal Systems of Liver. Platypus.

The Kiiiary System is dark and Portal System dotted.

RM Right Mesial or Cystic Lobe, LM Left Mesial or Cystic Lobe,
R Right Lateral Lobe, L Left Lateral Lobe, C Caudate Lobe,
S Spigelian Lobe, H Stomach. P Pancreatic Duct. D Duodenum.
N Duod.- 1 ntest. Flexure.

PLATYPUS AND ECHIDNA.

be wholly in the portal interval, which lies between the
inner extremities of the right and left lateral lobes. A
fine peritoneal fold is noted passing from the ventral
surface of the gall bladder and cystic duct to the lesser
omentum. At the portal interval it is joined by two main
hepatic ducts on each side, viz. right and left hepatic.
Into the left hepatic duct three main branches pass from
left mesial, left lateral, and spigelian lobes ; into the right
hepatic three main branches also pass, viz. from the right
mesial, right lateral, and caudate lobes. At the portal
interval the portal vein is posterior and the artery slightly
to the left between the two. The combined or common
bile duct then passes in the right extremity of the lesser
omentum for about 5 cm., lying at first between the lobus
caudatus and spigelian lobe and enters the duodenum
about 2.5 cm. from the pyloric knob. The pancreatic
duct opens into the common bile duct obliquely about
2-2.5 cm. from its termination in the duodenum and fol-
lowing somewhat the curve of the duodenum is traced on
the left in the pancreatic tissue to the spleen receiving
tributaries in its course. At the junction the common
bile duct is seen to be almost double in its circumference
that of the pancreatic duct. Thereafter, the circumfer-
ence of the combined hepatico-pancreatic duct is almost
double that of the common bile duct. At its termination
the duct loops slightly to the left. The opening into the
duodenum is minute and may be indistinguishable from
the inner surface of the duodenum till the duct is opened
and a hair seeker passed through. Furthermore, near
the termination of the duct a valvular projection is to be
seen, by which apparently the flow of bile is regulated.
This valve lies .5 cm. from the termination. Between the
valve and the duodenal wall the duct forms a dilatation,
but on passing through the bowel wall it narrows again.

PLATYPUS AND ECHIDNA.

Lesser Omentum. — Foramen of Winslow. — In the
Platypus there is no right margin of the lesser omentum
(gastro-hepatic) as in the human type. The gastro-
hepatic omentum is directly continuous with the meso-
duodenum; and this, with the duodenum which it sup-
ports and the portion of proximal colon related to it, can
be with the lesser omentum lifted in one piece, from the
dorsal wall — right kidney — and liver as far as the portal
interval. In the Echidna the duodenum is less mobile —
the mesoduodenum has shortened and the pancreas is
frequently fixed by the peritoneal adhesions to the caudate
lobe; but the lesser omentum is free, and so the right
margin becomes denned. This right margin is especially
defined in the human subject where the duodenum is fixed
dorsally. In the Platypus a big spleen and great omen-
tum have developed projecting to the left with the gap
(Foramen Winslow) in the mesogaster and upper meso-
duodenum on the right. The foramen is large and readily
admits the little finger. It is easily defined by throwing
the mesoduodenum — duodenum — and lesser omentum to
the left. In the human subject this cannot be done, so to
define it we pass our linger behind the right edge of the
lesser omentum. The foramen is limited above at the
portal interval — ventrally we have the mesoduodenum
with pancreas and lesser omentum — dorsally the fissure
between the lobus caudatus and spigelian lobe — and cau-
dally a fold from the mesoduodenum to the ventral part
of the inf. v. cava.

Pancreatic Duct in Platypus. — This is traced within
the mesoduodenum following the curve of the duodenum,
and though close to the latter structure at its proximal
portion gradually inclines out below, and may lie 3 cm.
from the duodenal wall. Opposite the junction of the
descending and transverse portions of the duodenum it

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Sto-maui, Duodenum, and Ducts. Platypus.

S Stomach. K Oesophagus, P. Pylorus. D Duodenum, E. Pancreas,
H Gall Bladder. L Hepatic Ducts. A Pancreatic Duct.
C Common Bile Duct.

PLATYPUS AND ECHIDNA.

forms an angle and is traced upwards and to the left
above the duod-intest. junction. It lies in the wall of the
lesser sac, which it leaves as the spleen is approached, and
then curves downwards towards the pelvis on the lieno-
mesocolic fold. Thus we can describe three portions, viz.,
descending, oblique and ascending, and descending, and
as the length of each portion is about 7 cm. the total length
is 21 cm.

Pancreas in Platypus. — The pancreas in Platypus,
though abundant, is more diffuse and mobile than in the
Echidna, in which we have a relative compactness and
Immobility. In the Platypus the most compact portion
is as a rule to be found on the extreme left in relation
with the lesser process of the spleen and descending part
of the left colon. A knowledge of the relationship of the
pancreas necessitates a brief knowledge also of the rela-
tionship of the spleen, stomach, and duodenum, as well as
left colon. The stomach is a small tubular sac succeeded
by a somewhat horseshoe-shaped duodenum about 18 cm.
long. The colon, which is swung on the common mesen-
tery, comes into relationship with mesoduodenum which
suspends the duodenum making it freely mobile, and fol-
lows the curve of the latter as in diagram. It then de-
scends swung on its own mesocolon into the pelvis. The
great omentum is attached above to stomach and duo-
denum, extending as far to right as, or even beyond, the
bile duct entrance. It does not include the colon but in
the region of the duodeno-jej. flexure is in relation with
its superior margin for about 2-4cm. Suspended in the
great omentum we have the body and greater process of
the spleen — the smaller process is outside the lesser sac,
being related to the descending part of the colon by a
fold, the left lateral or lieno-mesocolic fold. The pan-
creas diffuses itself in the duodenal loop between the

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layers of the niesoduodeimm, and as this is free so the
pancreas is quite movable on the right side. It is more
abundant below the relation of the colon to the meso-
duodenum than above it and strands are found to extend
along the common bile duct as far as the portal interval,
but it does not extend in the gastro-hepatic omentum to
the left of the duct, as in the Echidna. Except about the
entrance of the ducts there is frequently a distinct in-
terval in the mesoduodenum between the pancreas and the
duodenum. From the duodenal portion of the pancreas
a process is noted passing up and to the left in the lesser
sac, i.e., in relation with the great omentum, towards the
pylorus. Apart from the process the pancreas is traced
to the left in relationship with the colon lying at first
in the wall of the lesser sac for about 2-4 cm. and then
outside the sac it diffuses itself on the left aspect of the
mesocolon, coming into relationship with the fold con-
necting the left posterior smaller process of the spleen
with the mesocolon of the descending part of the left
colon. As stated, the pancreas at its termination forms
a someAvhat compact mass, and approaches close to the
left pelvic brim. It is important to note that there is no
pancreas in relationship either with the body of the spleen
nor with the greater right anterior process, both of which
are in relationship with the great omentum, being con-
tained in the lesser sac.

Portal Vein. — Two main branches are given oft' —
right and left lateral — the former, which first arises,
sending a branch to the caudate. On the left side, in ad-
dition, two small branches are noted to the spigelian lobe,
one from the main trunk and the other from the com-
mencement of the left lateral trunk. Finally, the main
portal trunk divides into two terminal branches, one to
the right mesial and the other to the left mesial lobe.

Biliary and Portal Systems of Liver. Echidna.

RM Right Mesial or Cystic Lobe, LM Left Mesial or Cystic Lobe,
R Right Lateral Lobe, L Left Lateral Lobe, C Caudate Lobe,
S Spigelian Lobe, P Pancreatic Duct joining Common Bile
Duct, H Stomach, D Duodenum, N Duod.-Intest. Flexure.

PLATYPUS AND ECHIDNA.

(b) Echidna. — Gall Bladder. — In the Echidna this
is also somewhat pear-shaped, usually distended with bile,
and presents for examination a fundus and body. Only
rarely can a narrowed portion or neck be defined. It
lies in a fossa on the under surface of the cystic or mesial
lobe, and it is not usual for the fossa to reach the ventral
edge of the liver. In one specimen there was an interval
of .75 cm. of hepatic tissue between the fundus and the
ventral edge. It measures 3-3.5 cm. in length and later-
ally 2.5 cm. The fundus usually projects beyond the
ventral border, and is mobile, being completely invested
with peritoneum, the body and cystic duct being invested
on the ventral surface and sides onlv. Dorsallv the cystic
fossa narrows, forming a notch lodging the proximal half
of the cystic duct, which thus lies between the right and
left portions of the cystic lobe. The remaining half of
the cystic duct lies in the portal fissure or interval between
the inner portion of the caudate and right lateral on the
right side and the left lateral on the left. On the other
hand the fossa may extend to the coronal fissure, so that
the cystic duct lies wholly related to the portal interval.

The Cystic Duct measures 1 cm. long, and at the
portal interval it is joined by the hepatic ducts, and
becomes the common bile duct. This is traced with the
hepatic artery on the left and the portal vein dorsallv
in the groove at the junction of the caudate and spigelian
lodes. It runs in the right extremity of the lesser omen-
tum (gastro-hepatic), which is more defined from the
mesoduodenum than in the Platypus, since the pancreas
is becoming more fixed and even adherent to the caudate
lobe. The common duct measures about 4 cm., and it is
joined by the pancreatic duct 2 cm. from its termination
in the duodenum, though in a female the distance was
only .75 cm. Contrary to Owen's opinion, I hav^ never

PLATYPUS AND ECHIDNA.

found a pancreatic duct opening into the duodenum inde-
pendently of the common duct. The combined duct sur-
rounded by pancreatic tissue is traced in the right margin
of the lesser omentum, and after running parallel and to
the right with the duodenum for 1 cm. enters it at a right
angle about 3 cm. from the thickened pylorus in a well
developed male, though in a female the distance was only
1.75 cm. Thus it forms a loop at its termination. As in
the Platypus, this portion is about double in circumfer-
ence that of the common duct, but opens into the duo-
denum by a distinct papilla, thus differing from that
Monotreme. A slight bulbous swelling .75 cm. long is
noted on the duct just before it enters the duodenal wall.
A valve is noted at the junction of the duct and the bulb-
ous swelling.

Hepatic Ducts in E<-hi<hi<t. — At the portal interval on
the right side a well defined trunk (right hepatic) is
noted, with branches passing into it from the right mesial
— right lateral — and caudate and spigelian lobes. On the
left side there may be a single trunk (left hepatic), with
branches passing into it from the left mesial and left
lateral lobes, or we may have a single branch from the
left lateral joining the cystic duct opposite the right
hepatic, and nearer the gall bladder a separate branch
from the left mesial lobe. A compromise between the two
(Hi the left side is depicted in the diagram (page k3)).

Pancreatic Duct in Echidna. — Although a single
pancreatic duct entering the common duct on the right
side is in my experience most frequent, nevertheless the
following conditions should be noted: —

(a) Single duct entering the common duct on the
right. It passes parallel with the latter in
the gastro-hepatic omentum for about .75
cm.

PLATYPUS AND ECHIDNA.

(/>) Two duets opening opposite one another — one
from pancreas in the gastro-hepatic omen-
tum— one from rest of pancreas.

(<l) Single duct on left — traced in the gastro-hep.
omentum towards the pylorus, then down
and to the right in mesoduodenum, and then
to left. Total length, 12 cm.

Pancreas in Echidna. — (1 ) The pancreas is a more
compact and less mobile organ than in Platypus, and may
be in close relation with the dorsal abdominal wall and
the lobus caudatus of the liver, so as to be regarded as a
"fixed'' organ. (2) The great omentum is well defined
and traced along the great curvature of the stomach, but
does not extend as far to the right along the duodenum
as in the Platypus. It never extends beyond the pylorus,
and may even end at the beginning of that elongated giz-
zard-like structure. It has the spleen on its left side, and
its length is lb' cm., and width below 12 cm. (3) There
is, as in Platypus, a well defined duodenal loop which
contains the main portion of the pancreas. Pancreatic
tissue may be traced to the left of the duct in the gastro-
hepatic omentum above the pylorus, and even reaching to
the stomach wall. It is also traced along the duct as far
as the portal interval of the liver. The pancreas related
to the duodenal loo]> is mobile usually, though the mobil-
ity is limited. This portion is usually connected to the
lobus caudatus of the liver by a peritoneal band. There
is a slight interval between the pancreas and the duodenal
wall, as in Platypus.

(4) The colon comes into relation with the pancreas
about the root of the mesentery and duod-intest flexure.
Here the pancreas is fixed dorsally in all specimens
examined. As in Platypus the body and right process of

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PLATYPUS AND ECHIDNA.

spleen are related to the lesser sac (great omentum),
while the left process is outside the lesser sac and connec-
ted to the mesocolon of the descending part of the left or
distal colon by the left lateral or lieno-mesocolic fold.
The great omentum comes down as far as the upper
border of the colon, but does not include it; and the pan-
creas— after more or less tilling the duodenal loop as
stated — is prolonged along the upper border of the colon
as a process forming the lower dorsal boundary of the
lesser sac, extending in an average specimen for about 2-3
cm. (It is to be noted that the main mass is above the
colic relation to mesoduodeiiuni, only a small amount
being found dorsal to the commencement of the mesen-
tery, while the reverse is the case in Platypus.)

In contradistinction to the Platypus the pancreas
does not extend to the left beyond the lesser sac, i.e., does
not come into relationship with the posterior process of
the spleen and the lieno-mesocolic fold. There is usually
a well defined groove in the pancreas for the reception of
the colon.

(5) In a male adult specimen the pancreas on the
right was closely related to the lobus caudatus of the liver
(thus lessening duodenal mobility), so that the whole
organ could be regarded as fixed. In this mammal the
distal colon was fixed, and not only the body and right
process, but also the stem of left process of spleen, were in
the lesser sac, only the nummular process being outside
and related to colon. The lesser sac dipped down sinistral
to the distal colon, and the pancreas also extended down
on the left of the colon. The lesser omentum and the
foramen Winslowii were poorly defined.

(6) In the Platypus the separation between meso-
duodenum and gastro-hep. omentum is ill defined,
and a gap is noted dorsal to the bile duct, i.e., fora-
men of Winslow. A band is noted (of which a

or;

Stomach and Liver in Echidna.

H Gall Bladdei with Common and Pancreatic Ducts, L Left Lobe
Liver, M Mesial (Cystic) Lobe of Liver, R Right Lobe Liver.
C Caudate Lobe Liver. S Stomach. P Pancreas, A Lesser
Omentum, E Rigid Pylorus (Sphincter), D Duodenum. () Great
Omentum. H Portions of Small Intestine, F Right Proximal
Colon. T Distal Colon.

PLATYPUS AND ECHIDNA.

trace is seen in Tas. Devil) from the dorsum of
duodenal pancreas to the inf. v. cava. But in the Echidna
the definition of gastro-hep. omentum (lesser omentum)
is distinct. The pancreas becomes attached by a peri-
toneal fold to the lobus caudatus, and this fold is really
continuous with one to the inf. v. cava (which is present),
so that the latter fold from pancreas to v. cava seen in
Platypus is the starting point in the fixation of duodenum
and pancreas. As a result, what may be regarded as a
twist is put on the "junction'' of the lesser omentum and
mesoduodenum, and the former becomes denned, forming
the anterior boundary of the foramen of Winslowii. In
the Platypus this, as stated, was a gap on the right of
gastro-hep. omentum and mesoduodenum, which were
practically continuous. In only one Echidna did the
condition resemble that of the Platypus, and here there
was no attachment of pancreas to caudate. This throws
light on formation of foramen Winslowii, and shows why
we go behind lesser omentum to enter the lesser sac.
Light is also thrown on the mobility of the caudate lobe-
after fixation of pancreas, then immobility; but mobile
first to give a yield to the band, and the pancreas itself,
when evolving, is diffuse and mobile. Why fixed duo-
denum and pancreas? For erect posture, i.e., no mobility
of ducts allowed, thus obviating torsion.

Portal Vein. — On the right side a single branc'i
passes, sending branches, one to right lateral, and another
to the caudate and spigelian lobes. On the left side two
branches are given off close together — one to left lateral
lobe, and the smaller to the left mesial lobe. The branch
to the right mesial would appear to be a continuation of
the portal trunk.

LIVER IN MACROPUS.

(KANGAROOS AND WALLABIES,)

Though certain minor differences may be noted the
following can be regarded as the type, as evidenced by
examination of Macropus Giganteus — ITalabatus —
Parryi, and smaller varieties, such as the Tasmanian
Wallaby.

The liver is somewhat obliquely placed — passing
down to the right — and lies in the epigastrium and right
hypochondrium.

Diaphragmatic Aspect. — The liver — both lateral and
cystic lobes — is closely attached dorsally by bands to the
tendinous portion of the diaphragm. The suspensory or
longitudinal ligament passes between the cystic lobe and
the diaphragm, and helps to separate the small left por-
tion from the main right portion of the cystic or mesial
lobe. It can be traced between the dorsal part of the
cleft for the gall bladder and the inf. v. cava, being short
where the cleft is prolonged dorsally as a fissure. In a
Macropus Parryi the longitudinal ligt. ran from the
middle of the left cystic and out from the gall bladder
fissure.

Three distinct divisions of the liver are seen on this
aspect, viz., large left lateral lobe — small mesial, or cystic
-and right lateral, intermediate in size, between the two.
In addition dorsally the left lateral aspect of the spi-
gelian lobe is seen, somewhat triangular in shape — with a

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KANGAROOS AND WALLABIES.

greatest dorso-ventral measurement of 5 cm., and lateral
10 cm. The inf. v. cava is seen to run between right
lateral and mesial lobes and the spigelian lobe, and this is
seen to be continuous with the dorsal parts of both the4
cystic and left lateral lobes.

Left Lateral Lobe. — A striking feature is the rela-
tively large size of this lobe, which is seen to be separated
from the mesial lobe by an irregular fissure (left lat. fis-
sure), which does not reach the inf. v. cava dorsally,
where the left lateral — mesial — and spigelian lobes are
connected. This lobe measures 11 cm. dorso-ventrally,
and 9 cm. laterally. Behind the dos< (-internal promin-
ence of the left lateral lobe, between it and the spigelian,
and then on the left aspect of the spigelian, which is
grooved for it, we have the (esophagus passing to the
stomach.

Mesial or Cystic Lobe. — This is separated from the
right lat. lobe by the right lateral fissure, which does not
frequently pass so far dorsally as the inf. v. cava, and
measures 9 cm. laterally and 7.5 cm. dorso-ventrally. It
is separated into two portions — the left smaller, and the
right larger — by the cleft for the gall bladder in front,
and the longitudinal ligt. dorsallv. The cleft, which may
be fissured dorsally, measures 3 cm. dorso-ventrally, and
3 cm. laterally, and the gall bladder is seen freely on this
aspect. Usually the ventral margin of the liver is formed
by the left and right lateral lobes, and so the gall bladder
is not seen at that edge. Sometimes* the right portion
of the cystic lobe may partake in the ventral margin, and
in the smaller varieties of the Macropodida3 the whole of
the mesial lobe may partake, so that the gall bladder is
seen on the ventral edge.

KANGAROOS AND WALLABIES.

Right Late red Lobe. — This is smaller than the left
lateral, and is separated from the cystic lobe by the right
lateral fissure. It is concave below for the reception of
the right kidney, and presents a partial fissure 3 cm. long
on the thin ventral edge. It measures 12 cm. laterally, and
10 cm. dorso-ventrally. The inf. v. cava is visible dorsally
in its hepatic relationship, which is about 9 cm. long. It
is placed on the dorsal aspect of the right lateral and
right part of the cystic lobes, between these and the lobus
spigelii — its exit being at the back of the right cystic lobe,
almost on the level of the gall bladder cleft.

Visceral Surface. — Here the striking features are the
relatively large size of the left lat. lobe, presenting neither
fissures nor lobes, and the projection below it, and dorsal
to the lesser omentum, of the spigelian lobe, which is
broad at the base and pointed at the extremity.

Left Lateral Lobe. — This lobe, which is separated
from the mesial or cvstic lobe bv the left lat. fissure,
usually hides part of the gall bladder and its cleft, as well
as the smaller left portion of the cystic lobe. In a Wal-
laby the left lat. lobe was so large as to occlude completely
the two portions of the cystic lobe — gall bladder — and the
inner portion of the right lateral lobe. The stomach in
Macropus assumes a somewhat V-shape in the abdomen,
with a large left portion including the fundus and its
single or double pocket and also the abdominal oeso-
phagus, and smaller right portion. The left lat. lobe is
related to the summit of left portion, whilst the summit
of the right portion is related to the right part of the left
lateral, cystic, and right lat. lobes — the pylorus, and com-
mencement of the duodenum being related to the dorsal
or lower part of the right lateral lobe.

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KANGAROOS AND WALLABIES.

Spigelian Lobe. — A well developed spigelian lobe is a
characteristic feature of the liver of Macropus. It pre-
sents three surfaces — an upper corresponding to the
under surface of the left lat. lobe, and a right and left
lateral for the stomach. At the dorsal part of the left
surface is a groove for the abdominal oesophagus, which
is of considerable length in the Macropodidre, and which
passes between the spigelian lobe and the dorso-mesial
projection of the left lat. lobe. It may project as far for-
ward as the level of the ventral border of the left lat. lobe,
and in Parry's Kangaroo I have seen it divided into two
lobes by a fissure. It dips down behind the lesser omen-
tum, between the two portions of the stomach, forming,
as it were, a separation between the two.

Cystic or Mesial Lobe. — This is divided into two
parts by the cleft of the gall bladder — a larger right and
smaller left. The smaller left portion is always hidden by
the left lat. lobe, which extends dextrally as far as the
gall bladder cleft, so that only part of the bladder is seen
— the main projection of the bladder being on the dia-
phragmatic, or upper surface. The Cystic Duct passes
between the left lat. and the right cystic lobes, and the
Common Bile Duct, with the artery and portal vein, are
seen passing also in a groove between the right lateral and
spigelian lobes.

Right Lateral Lobe. — Two portions, as on the dia-
phragmatic surface, may be recognized separated by a
partial fissure, viz., an upper small and a lower larger
portion hollowed below for the reception of the kidney. In
a Macropus Parryi, and in a young Wallaby, I have found
the upper portion to be more defined and mobile, project-
ing ventrally to the lower part and to the right cystic lobe
— the ' ' partial ' ' fissure extending to the vena cava. There

33 d

KANGAROOS AND WALLABIES.

is no definite caudate lobe in Macropus. We may see a
projection on the inner part of the right lat. lobe corre-
sponding to it, but the important point is that the vena
cava has come to the ventral surface. Why the fissure?
Is this acquired for more elasticity in relation to the
pyloric portion of the stomach — remembering the rela-
tively enormous size of the Maeropod's stomach — or are
we dealing with a primitive right lobe, i.e., the upper part
to be regarded as right lobe, since it is separated from the
cystic by a fissure, and the lower to be regarded as cau-
date, hollowed below for the kidney. If we do regard the
lower portion as caudate the inner portion has disap-
peared, and the two portions are now practically one.
The liver of the Macropod then is important in reference
to the evolution of the caudate lobe, suggesting atrophy
internally and fusion — unification — externally.

Inf. V. Cava.'- -This is seen to lie obliquely on the
inner or left margin of the right lateral lobe, and passing
ventral to it between the spigelian on the left, and the two
parts of the right lateral on the right, are the portal
vein, artery, and common bile duct — the portal vein and
inf. v. cava being in close relationship. The vena cava
completely separates the spigelian and right lateral lobes
-no caudate lobe is present — and the spigelian lobe is
seen to be really connected with the left lat. lobe, and not
with the right lateral.

Lesser Omentum. — A continuity is established with
the suspensory membrane at the inf. v. cava on the dia-
phragmatic aspect. The membrane, which is really the
old ventral mesentery, passes behind the projection on the
dorso-internal aspect of the left lat. lobe to the visceral
surface. The lesser omentum is traced along the internal
or right margin of the left lat. lobe to the portal interval,
being seen immediately above the lobus spigelii.
Dl 34-

KANGAROOS AND WALLABIES.

Gall Bladder and Ducts. — The gall bladder is placed
in the cleft in the cystic or mesial lobe, and owing to the
projection to the right of the large left lat. lobe it is
usually only seen partly from the visceral aspect, though
projecting freely on the diaphragmatic face. As a rule
it is best examined on the visceral aspect by removing the
right portion of the left lat. lobe. It may be described
as a somewhat rounded sac, 4-5 cm. long, with a greater
mobility than the human bladder. Its ventral, two-thirds,
are completely invested by peritoneum, while the dorsal,
third, is less mobile, being invested on the under surface
and sides only, and attached to hepatic substance above.
From the dorsal extremity of the gall bladder the Cystic
Duct, 2-2.5 cm. in length, passes, lying in a groove — the
continuation of the gall bladder cleft — between the two
portions of the mesial lobe. It is joined at its termina-
tion in the portal interval by the Hepatic Ducts, and be-
comes the Common Bile Duct. The portal interval, or
fissure, which corresponds to the region where all the
lobes meet, is placed between the right cystic and right
lateral lobes dextrally, and the left lateral and spigelian
on the left,

Hepatic Ducts. — On the left side the left hepatic
trunk is formed by the union of two branches — one from
the left cvstic or mesial, and the other from the left
lateral lobe; near its junction with the cystic duct it re-
ceives a branch from the spigelian lobe. On the right
lobe main trunks are noted — the smaller ventral one from
right mesial or cystic lobe, and the larger more dorsal
branch from the right lateral lobe.

Co unit on Bile Duct. — This is formed by the junction
of the cystic and hepatic ducts, and passes down with the
hepatic artery and portal vein — the vein lying dorsally
as in the human liver— between the lobus spigelii, on the

Biliarv and Portal Systems. Liver. Kangaroo.

R Right Lateral Lobe, L Left Lateral Lobe, S Spigelian Lobe,
LM Left Mesial or Cystic Lobe, RM Right Mesial or Cystic
Lobe, P Pancreatic Duct joining Common Bile Duct, H Portion
of Stomach, D Duodenum, N Duod. -Intestinal Flevure.

KANGAKOOS AND WALLABIES.

left, and the right lat. lobe on the right. It is traced on
the right side of the lesser omentum, then behind the
pylorus of the stomach, and coming into relation with
pancreatic tissue it enters the mesoduodenuin, which is
not so defined as in Trichosurus, and finally terminates
about the middle of the ascending stem of the duodenal
loop, though in two Wallabies I found it entering close
to the duod-intest. flexure. The opening into the duo-
denum, which is characterized by a slight papillary eleva-
tion, and is guarded by a sphincter, lies about 12-14 cm.
from the pylorus in Macropus Gig, and about 7-10 cm. in
Macropus Ualab. The pancreatic duct, which is usually
relatively fine, and can be traced to the spleen on the left
above the root of the mesentery, joins the common bile
duct 3-5 cm. before its termination in the duodenum.
From the entrance of the pancreatic duct to the portal
fissure, i.e., common bile duct, is 7-8 cm. The combined
hepatico-pancreatic duct is much greater in circumfer-
ence than the common duct, and has a thickened somewhat
pipe stem feel. In a great Kangaroo I have found the
circumference of this portion 2.5 cm., and in two Wal-
labies the terminal .5 cm. was bulbous, forming almost a
right angle with the main duct before entering the duo-
denum. The lumen of the thickened hepatico-pancreatic
portion of the duct is narrowed, and the interior rugous.
The thickening of the wall suggests greater intra-duo-
denal tension than in the other Marsupials. In some
specimens a valvular arrangement at the commencement
of this portion is suggested. It is interesting to note the
presence of a band, 2.5 cm. broad, which passes across the
pylorus of the stomach from the right of the lesser omen-
tum to the right of the great omentum. The thickened
part of the duct usually begins just caudal to this band.
This, though adherent slightly to the pylorus, forms a
continuity between the colon at the pylorus and the lesser

C7 OMENTUM

CO LOU

/LEO CyCCAL

JunC TION

MESOCOLON

The Gastro-Intestixai. Tract i.\ Kangaroo.

KANGAROOS AND WALLABIES.

(gastro-hepatic) omentum, and should be compared with
the fold (ventral) found in Chameleon, and in the
Cheiroptera.

Portal Vein. — The tirst branch given off is a well
defined one on the right to the right lateral lobe. More
ventrally on the left is a small branch to the spigelian
lobe ; and ventral to that a large branch to the left lateral
lobe. It finally terminates in two divisions, one to the
right mesial, and a smaller one to the left mesial lobe.

Pancreas. — If the stomach and duodenum be re-
tracted towards the left a well defined portion of pancreas
is seen in relation to the mesoduodenum, with its maxi-
mum development in the region of the thickened hepatico-
pancreatic duct. It is traced upwards towards the liver
along the common duct, though not reaching as far as
the portal fissure, and may be traced in the lesser omen-
tum towards the spigelian lobe. This right portion lies
ventral to the inf. v. cava, off which it can be raised, and
does not usually descend to the lower part of the duo-
denal loop. It is traced to the left behind the stomach as a
well defined compact gland, 3 cm. in width, passing above
the root of the mesentery in relation to the dorsal abdo-
minal wall. On the left of the root it defines the lower
boundary of the lesser sac, and lies ventral to the left
adrenal gland and upper pole of the left kidney, from
which it is free ; and although a fine strand, is continued
on to the right or omental process of the spleen, i.e., passes
into the lesser sac, the main portion of the pancreas,
passes downwards in relation to the left, posterior, or
dorsal process of the spleen— on the lieno-mesocolic fold
— and is continued to the extremity as a tapering process.
This part, though forming an angle with the body of the
pancreas, is to be regarded as the true continuation of the
gland on the left.

LIVER IN WOMBAT.

(PHASCOLOMYS.)

The liver extends to the left beA^ond the mid line, and
is found in the epigastric and right and left hypochon-
driac region.

Diaphragmatic Surf (tee. — Left Lateral Lobe. —
Specimen A. — Mewed from this aspect we are struck by
the large relative size of the left lateral lobe, i.e., the por-
tion to the left of the mesial or "suspensory'' ligament.
The right margin of the liver is seen to be larger than
the left, and the dorsal than the ventral. Though the liver
of the Wombat is approaching the human, and unifica-
tion of the hepatic lobes is becoming the type, yet we can
— though much less distinctly than in other Marsupials —
define a left lateral — right lateral — and mesial or cystic
lobes. In this adult the left lateral lobe measured 17 cm.
dorso-ventrally, and 13 cm. laterally. On the inner side
dorsally a concavity is noted for the passage of the oeso-
phagus. Between this lobe and the mesial or cystic is a
fissure about 3.5 cm. long, and between its dorsal ex-
tremity and the inf. v. cava is 2 cm. of hepatic tissue, so
that these lobes are becoming linked up, only the suspen-
sory ligament passing between the fissure and the inf.
vena cava. To the left of this fissure, i.e., on the left lat.
lobe, another complete, though small, fissure is seen only
1.5 cm. long, and between these two fissures is a portion of
hepatic substance, measuring 1 .5 cm. laterally. It repre-
sents the left cystic of other Marsupials, and the fissure is

Diaphragmatic Surface of Liver. Wombat. (Specimen A.)

B Gall Bladder Cleft, RM Right Mesial or Cystic Lobe. IN Inter-
mediate Cystic Lobe, LM Left Cystic Lobe, L Left Lateral Lobe,
R Right Lateral Lobe, F Relationships to Diaphragm, E Oeso-
phagus, V Inf. Vena Cava.

WOMBAT,

the remains of the left lateral fissure. The larger fissurer
which here separates the mesial or cystic lube from the
left lateral lobe, represents the mesial or cystic fissure
separating the intermediate cystic from the left cystic
lobe. In B, however, unification is a more prominent
feature; the fissure on the left (i.e., old left lat.
fissure) measures 1.5 cm., and the fissure dextral
to that — connected with the suspensory ligt. — only
measures 1.75 cm. In C we see a much more primitive
type of liver. The three portions of the mesial or cystic
lobe are defined. The left lateral fissure between the left
lat. and left cystic lobes is 6.5 cm. long, and the mesial or
cystic fissure between the intermediate and left cystic is
4-5 cm. long, so that only 2 cm. exists between the dorsal
extremities of these fissures and the inf. v. cava.

Mesial or Cystic Lobe. — A. — This is separated on the
right from the right lateral lobe by a curved fissure —
completely through hepatic tissue — measuring 5 cm. long.
Between its left extremity and the vena cava 2 cm. of
hepatic tissue is found, so that the cystic and right lateral
lobes arc also linking up. The mesial lobe measures 11
cm. dorso-ventrally, and 7 cm. laterally, and is charac-
terized by the presence ventrall}7 of a somewhat quadri-
lateral cleft for the gall bladder, 4 cm. dorso-ventrally,
and 1.5 cm. laterally, and so the gall bladder is seen on
this aspect. The ventral margin of the liver is formed
partly by the mesial and partly by the left lateral lobes.

B. — Here the right lateral fissure is only 2 cm. long,
and the gall bladder cleft measures 2 cm. dorso-ventrally,
and .75 cm. across.

C. — As stated above, the three portions of the mesial
or cystic lobe, viz., left, intermediate, and right are well
defined. There is a greater definition of the cystic from

(C)

Diaphragmatic Surface of Liver. Wombat. (Specimens B, C, D.

B Gall Bladder Cleft, RM Right Mesial or Cystic Lobe, IM Inter-
mediate Mesial Lobe, LM Left Mesial or 'Cystic Lobe, R Right
Lateral Lobe, L Left Lateral Lobe, V Inf. Vena Cava,
F Relation to Diaphragm, E Cleft for Oesophagus.

WOMBAT.

the right and left lateral lobes than in the other speci-
mens. The right lateral fissure measures 3.5 cm., and
the cleft for the gall bladder measures 4.5 cm. dorso-
ventrally, and 1.25 laterally

D. — Here there was no right lateral fissure, only a
gap on the dextral margin defining the right portion of
the mesial from the right lateral lobe.

Right Lateral Lobe. — A. — This is prolonged down
ventral and external to the right kidney as a somewhat
pointed extremity, and is concave below for the reception
of that organ. It measures dorso-ventrally 11 cm., and
laterally 10.5 cm., being larger in size than the mesial
lobe. Running along its inner or left part is the inf. v.
cava, which is seen leaving the liver on its passage to the
diaphragm above the upper part of the interval or gap
between the right and left lateral lobes. The wall of the
inf. v. cava in its hepatic relationship, which measures
7 cm., is seen dorsally, i.e., is not covered by hepatic tis-
sue.

Relations to Diaphragm. — In the region correspond-
ing to the entrance of the oesophagus and the exit of the
inf. v. cava the tendinous part of the diaphragm is closely
applied to the liver. On the sinistral side the posterior
or dorsal edge of the left lateral lobe is connected to the
muscular and tendinous portion of the diaphragm by a
thin but strong band, the width of which on the extreme
left = 4.5 cm., and so a good deal of mobility is allowed to
this part. Internally, i.e., approaching the inf. v. cava,
as shown in the diagram, the membrane encroaches on the
diaphragmatic surface. On the dextral side the attach-
ment of the membrane is rather to the dorsal portion of
the diaphragmatic surface than to the dorsal edge, and the
membrane is narrower, with the greatest measurement
only 3 cm., and so dextrally the liver is less mobile.

Visceral Surface of Liver. Wombat. (Specimen A.)

B Gall Bladder, R Right Lateral Lobe, L Left Lateral Lobe,
RM Right Mesial or Cystic Lobe, LM Left Mesial or Cystic
Lobe, IM Intermediate Mesial or Cystic Lobe.

WOMBAT.

Suspensory Ligament. — This is well defined, and is
traced from the back of the proximal fissure on the left
of the gall bladder — into which it may project — to the inf.
v. cava. It is attached above to the tendinous portion of
the diaphragm, and at its ventral margin it may measure
5.5 cm. In one specimen I saw some tough bands attach-
ing the ventral part of the liver, in the region of the
mesial or cystic fissure to the diaphragm.

Visceral Surface. Bight Lateral Lobe. — This is de-
fined from the rest of the liver by means of the right
lateral fissure. Its lower or caudal surface — which may
be fissured and lobulated or smooth — is hollowed below
for the reception of the right kidney. The inner portion
of this surface is in relation with the descending duo-
denum, and the outer part is related to the proximal
colon. This lobe is usually smooth, and the caudate and
spigelian lobes are rudimentary. On the inner side of
this lobe is a small raised portion, at the inner and back
of which the inf. v. cava passes. This may be regarded as
the caudate portion, and it is prolonged to the left in some
specimens as a small narrow process scarcely deserving
the name of the spigelian lobe, ventral to which pass the
portal vein, artery, and bile duct. Strands of hepatic
tissue are usually noted on the inner and ventral sides of
the inf. v. cava, as it lies on the sinistral margin of the
right lateral lobe. The large portal vein may measure
2.5 cm. laterally. Ventral to it are the common bile duct
and the hepatic artery, and dorsally is the inf. v. cava,
with which it is in direct relationship.

Left Lateral Lobe. — (A) This is the largest portion of
the liver. It is smooth, and presents the concavity dorso-
internally for the oesophagus. The lobe is concave on this
aspect for the left large or cardiac portion of the stomach,

WOMBAT.

and more ventrally the colon is related to this surface.
On its inner aspect some Assuring may be noted. On its
ventral edge is a fissure (complete), 1.5 cm. long-, which
is prolonged dorsally as a depression or groove for 3 cm.,
passing obliquely inwards to the right margin of the lobe.
This groove and fissure define a projecting lobnle (4 cm.
dorso- ventrally ) , which is now connected to the left
lateral lobe, and represents the remains of the left cystic
lobe — the groove and fissure representing the original
left lateral fissure.

(B) Here the fissure was only .75 cm. long, and the
oblique groove, apart from its termination, was nothing
more than a faint depression, so that the fusion of the
cystic (left) and left lateral lobes was more pronounced
than in the preceding.

(C) Here the separation of the left cystic lobe and
left lateral lobes was by a complete fissure (left lateral
fissure) 4 cm. long.

(D) Here there was no fissure, even anteriorally, but
a well denned groove or depression, so that the old left
cystic was defined, and presented some secondary Assur-
ing and lobulation.

Mesial or Cystic Lobe. — (A) The separation between
the left lateral and cystic lobes is by means of a fissure,
ventrally, and a groove dorsally reaching to the portal
interval — the total length of which may reach 7 cm., viz..
fissure 3 cm., and groove 4 cm. The whole of this corre-
sponds to the longitudinal fissure of the human liver. The
fissure and groove represent the interval (cystic or mesial
fissure) seen in more primitive forms between the inter-
mediate cystic and left cystic lobes. With this fissure
the longitudinal or suspensory ligament is connected-

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WOMBAT. '

hence the selection value for the passage of the umbilical
vein. In some specimens, whilst the fissure is the remains
of the old cystic or mesial fissure, the groove may be re-
garded as the remains of the dorsal part of the left lateral
fissure. This would be the case where the mesial or cystic
fissure had failed to reach the portal interval.

(B) Here the left cystic has fused with the left lateral
lobe, and although only a faint impression remains be-
tween the two, yet dorsally the remains of the old left
lateral fissure is more clearly defined, curving on to the
right edge of the left lateral lobe. The longitudinal fis-
sure separating the cystic from the left lateral lobe is
well defined ventrally, but by a groove dorsally, and is
the remains of the cystic fissure between the left and
intermediate cystic lobes.

(C) Here, although the left lateral fissure is well de-
fined, and measures 4 cm., yet it does not reach the portal
interval, as there is commencing fusion dorsally of the left
cystic and left lat. lobes, but the cystic fissure between the
intermediate and left cystic lobes is continued as a groove
between the left lateral lobe and the narrow dorsal part
of the intermediate cystic lobe.

(D) Here the left cystic has fused with the left
lateral lobe, leaving a well defined groove, representing
the old left lat. fissure. Between the cystic and left lat.
lobes is a fissure ventrally 1.5 cm. long, continued dor-
sally as a well defined groove— longitudinal fissure — and
is the remains of the mesial or cystic fissure between the
original intermediate and left cystic lobes. Into this the
groove representing the old left lateral fissure ends, so
that there was no question of its dorsal part being the
dorsal portion of the longitudinal fissure.

49 e

WOMBAT.

(A) The mesial or cystic lobe is divided into two por-
tions, viz., left and right cystic, by the gall bladder cleft
and groove for the cystic duct. The left portion corre-
sponds to the intermediate cystic in the triparite cystic
lobes, and to the lobns qnadratus in man — the right por-
tion being the old right cystic lobe, and is the larger of the
two. The cystic lobe is separated from the left lateral by
the longitudinal fissure explained above, and from the
right lateral lobe by the right lateral fissure. The sides of
the cleft are hollowed for the reception of the gall blad-
der, and the cleft is prolonged dorsally as a groove for the
cystic duct between the right and left portions — the latter
of which is greatly narrowed dorsally. The right cystic
portion is usually smooth, though it may present some As-
suring at the cleft. The smaller left lobe is narrow dor-
sally, and one can understand how this latter part might
disappear and leave a condition similar to the human
liver. A projection may be seen on the right margin of
the left part, due to an accommodation effect for the gall
bladder.

(B) Here the cystic lobe as a distinct entity is least
marked of all the specimens. We have a distinct lobus
qnadratus as the dorsal narrow part of the left por-
tion, i.e., old intermediate has become detached, and only
measures 1.25 cm. in length, and .5 cm. laterally. Apart
from this small portion the fissure for the cystic duct and
the longitudinal fissure would be merged very much as
in the human liver.

(0) Here, as on the dorsal aspect, we distinguish the
three divisions of the cystic lobe, viz., right, intermediate,
and left. For the ventral, two-thirds the right and inter-
mediate portions are of almost equal size, but dorsally
the intermediate portion is greatly narrowed, so that
while laterally at the ventral margin it equals 4 cm., at the

Liver, Stomach, and Spleen. Wombat. (Specimen D.)

W Dorsal Abdominal Wall, K Kidneys, R Pancreas. T Spleen,
S Stomach. P Pylorus, D Duodenum. B Gall Bladder. R Right
Lateral Lobe, L Left Lateral Lobe. RM Right Mesial Lobe.
IM Intermediate Mesial or Cystic Lobe, LM Left Mesial Lobe.

0'2

WOMBAT.

portal interval it is a pointed extremity, i.e., is atrophy-
ing. Although apparently so primitive, yet this liver
would approach the human type if the left cystic and
left lateral lobes were linked up.

(D) Here the greatest width of the right mesial or
cvstic lobe was 3.5 cm., and of left 1.5 cm. The dorsal
extremity of the left part was only l-3rd cm. wide, and did
not reach the portal interval, i.e., the fissure for the cystic
duct and the longitudinal fissure are being merged, since
the dorsal portion of the left cystic is disappearing. Thus
we see how the lobus quadratus becomes defined dorsally.

Gall Bladder. — This is a somewhat broad sac, meas-
uring, in a large specimen, 4-5 cm. dorso-ventrally, and
about 3 cm. laterally. In one male specimen the gall blad-
der was unusually small, only measuring 2 cm. dorso-
ventrally, and 1 cm. laterally. It usually projects beyond
the ventral border of the liver, and is lodged in the broad
cleft or interval between the right and left portions of
the mesial or cystic lobe (corresponding to the right and
intermediate of the tripartite mesial lobe), and is seen
both on the dorsal and ventral surfaces. It is mobile,
being invested by peritoneum completely for the ventral
4-5ths, the dorsal l-5th being invested on the upper and
under surfaces, but bound laterally to the margins of the
cleft.

Cystic Duct. — This passes back in the groove on the
under surface of the cystic or median lobe, between its
right and left divisions, though dorsally portion of the
left lateral lobe may take part in its boundary. It ex-
tends from the cleft for the gall bladder to the portal
interval, and is invested by peritoneum on the under sur-
face and sides being attached above. It measures 4.5 cm.
to 6.5 em. long, and is joined by the hepatic ducts, and
becomes the common bile duct.

Visceral Surface of Liver. YV'omuat. (Specimens D, E.)
P, (kill Bladder, L Left Lateral Lobe, K Right Lateral Lobe^
IM Intermediate Medial or Cystic Lobe, KM Right Mesial or
Cvstic Lobe. LM Left Mesial or Cystic Lobe.

WOMBAT.

Hepatic Ducts. — On the left side two main trunks arc
seen, the interval between them varying from 1-1.5 cm.,
viz., a ventral one receiving brandies from the left mesial
and ventral part of the left lateral lobes — which latter
may be absent — and a dorsal branch from the left lateral
lobe.

Dextrally, two main branches are also seen, viz., a
ventral one from the right mesial or cystic lobe, which
may be absent, and a dorsal one from the right lateral
lobe, which may receive branches from the right mesial
also. The right and left ventral hepatic ducts join the
cystic between the right mesial and thin part of the left
mesial, i.e., before reaching the portal fissure. The
right and left dorsal hepatic ducts join at the portal in-
terval.

Com m o u Bile Duel. — This duct, formed by the junc-
tion of the cystic and hepatic ducts, passes with the he-
patic artery and portal vein (which is placed dorsally),
on the inner side of the light lat. lobe, and in front of the
spigelian projection from the right lobe, when that is
present. it is traced on the right of the gastro-hcpatic
omentum behind the pylorus and commencement of the
duodenum, and descends in the substance of the pancreas,
from which it has to be dissected — within the doudenal
loo}) — to finally terminate in the ascending limb of the
duodenum lying nearer to the duodeno-intest. flexure than
to the duodenal bend. It may even terminate just
proximal to the flexure. The width of the common duct
is .75 2m., and its length measures 9-10 cm., so that from
gall bladder to duodenum equals 14-16 en:.

Pancreatic Duet. — A dissection of this structure on
the right side, where it is related to the common duct, is
at first associated with some little difficulty. Passing
from left to right it forms a bend, and is traced running

Biliary and Portal Systems. Liver. Wombat.

H Stomach, D Duodenum, X Duod.-Intest. Flexure, P Pancreatic
Duct, L Left Lateral Lc.be. R Right Lateral Lobe. IM Inter-
mediate Mesial or Cystic Lobe, RM Right Cystic Lobe, LM Left

Cystic Lube.

5b'

WOMBAT.

down within what may be regarded as the head of the
pancreas parallel, and to the left of the common duct.
About 3-4.5 cm. from the termination of the latter the
pancreatic duct comes into close relation with it, be-
coming adherent to its wall, although it can be separated
by careful dissection right down to the intestine.

As the wall of the pancreatic duct is thinner than that
of the common duct it can be easily torn. It finally ter-
minates with the common duct at the summit of a well
defined papilla in the interior of the duodenum, which lies
about 14-16 cm. from the pyloric sphincter. From this
papilla a probe can be passed directly into either the
common or the pancreatic duct. The common duct is
usually about twice the size of the pancreatic duct.

Lesser (Gastro-Hepaiic) Omen turn. — The right mar-
gin is defined on account of the comparative dorsal fixa-
tion of the right pancreas, whilst the left margin is more
defined than in the other Marsupials. It is for the most
part attached above to the portal fissure, and is traced on
the left to the oesophagus, lying dorsal to the mesial pro-
jection on the inner margin of the left lateral lobe.

Portal Vein. — The first branch is a well defined
branch on the right to the right lateral lobe. More ven-
tral is a large branch, on the left, to the left lateral lobe.
Finally, two smaller branches are noted, one on right to
the light mesial, and one on the left, to left mesial and
ventral part of the left lateral lobes.

Pancreas. — Of all the Marsupials and Monotremes
the pancreas of the Wombat is the one that most re-
sembles the human type. A head, body, and, in many
cases, a tapering left portion, or tail, may be dis-
tinguished. It is compact, and extends from the duo-
denal loop on the right to the spleen on the left side. The

WOMBAT.

main mass of pancreas (the head) is found applied to the
left of the upper half of the descending limb of the duo-
denum, though pancreatic tissue is found filling the duo-
denal loop as well. It is not found extending along the
common duet to the portal fissure. The head is character-
ized by a forward projection on the ventral surface.
Though there is a limited amount of mobility allowed
the duodenum nevertheless the head and commencement
of the body of the pancreas (which latter lies above the
root of the mesentery) may be regarded as fixed dorsally
— the cephalic mass lying opposite the gap between the
right and left lobes of the liver. The body of the pancreas
might be best described as a process passing from about
the middle of the left margin of the head across the epi-
gastric region above the root of the mesentery and the
duod-intest. flexure to the left hypochondrium, and
slightly narrowing as the inner or right surface
of the spleen is reached. I have see1! the reverse,
i.e., a narrow right body and a broad left. In
an adult the body was (> cm. long, and the head
measured 10 cm. long, and 3 cm. across, while the
left extremity, which was much thinner, was 2-3 cm.
broad. Pancreatic tissue is found extending in the right
of the gastro-hep. omentum towards the liver in relation
to the common bile duct. As it pusses to the left of the
root of tlie mesentery to the mesocolon it is seen to form
the Lower boundary of the lesser sac — not being, however,
itself included. On the left side it may send a small pro-
cess to be included in the lesser sac. The important point
is that outwards from the root of the mesentery to the
spleen the pancreas (i.e., really the body and tail) is mov-
able, since it can be lifted with the spleen from the dorsal
wall and the front of the upper part of the left kidney, to
which it lies ventral. It lies in relation to the left lateral
or lieno-mesocolic fold, which is seen to be somewhat tri-

WOMBAT.

angular in shape. Above, the fold is attached to what
may be regarded as the left post, process of the spleen.
Its left margin is free, and below it is attached to the
caudal pole of the left kidney. Occasionally the left por-
tion of the pancreas may be more compact and more fixed
dorsally. The greatest length of the pancreas from side
to side is 11 cm.

Motes on Diagrams of Visceral Surface of Liver.

Wombats (A, and D,),

Specimen (A). — The portions L.M., though repre-
senting the left mesial or cystic of the tripartite cystic
lobe, are now part of the left (lateral) lobe, as is definitely
shown on the diaphragmatic aspect. The anterior por-
tion is still separated at ventral margin by a fissure, but
on the visceral surface there is only a groove between the
two, which is not seen diaphragmatically. The longitudi-
nal fissure is between the portions I.M. and L.M.

I.M. represents the intermediate cystic or mesial of
the tripartite, but is now L.M. The longitudinal fissure
corresponds to the cystic or mesial fissure of the tripar-
tite cystic lobe and on diaphragmatic surface, as is shown
in diagram, it is related to the suspensory ligament.

Specimen (ZJ).--The portion L.M. is now part of the
left (lat.) lobe, and should be labelled L. The groove be-
tween these two portions, L.M., and the large portion, L.,
represents the old left lateral fissure. I.M represents the
intermediate lobe of the tripartite cystic lobe, and is now
I j.M. Its left boundary — the longitudinal fissure — repre-
sents the old mesial or cystic fissure, and is connected on
diaphragmatic surface with the suspensory ligament.

Diaphragmatic Surface of Liver. Wombat.
(Specimens E, F.)

B Gall Bladdei, IM Intermediate Mesial or Cystic Lobe, KM Right
Mesial or Cystic Lobe, LM Left Cystic Lobe, L Left Lateral
Lobe, R Right Lateral Lobe, V Inf. Vena Cava. F Relation to
Diaphragm.

WOMBAT.

Notes on Liver of Wombat.

Specimen E,

In this specimen I was struck by the large relative
size of the left and mesial lobes compared with the right
lobe.

The measurements were : —

Laterally. Dorso-ventrally.
Right Lobe 7 cm. . . 5 cm.

Mesial .... 16 cm. . . 13 cm.
Left Lobe . . 13 cm. . . 15 cm.

In this large specimen interesting light is thrown on
the evolution of the mesial lobe in Phascolomyidae.

Visceral Surface. — -The small right (lat.) lobe, large
left (lat.) lobe, and the mesial or cystic, consisting of two
main divisions, were all distinguishable — the left lobe of
the mesial being mainly occluded, however, by the left lat.
lobe, which projected as far dext rally as the visceral sur-
face of the right mesial. The lower part of the original
left mesial has fused to the left (lat.) lobe, an irregular
depression being between the two. The left mesial now
consists of the upper original part of the left mesial and
the lower part of the intermediate mesial, only a partial
Assuring being between the two. This left mesial is
separated from the left (lat.) lobe by the original left lat.
fissure above, and the remains of the mesial or cystic fis-
sure below, and as will be seen on the diaphragmatic sur-
face, the upper part of the intermediate mesial or cystic
lobe (lobus quadratus) has almost disappeared.

Diaphragmatic Surface. — Between the mesial and
right lobes is the complete right lateral fissure. (Not
shown in the diagram.) It measures 6.5 cm., and between
its dorsal extremity and the inf. v. cava are 5 cm. of

WOMBAT.

hepatic tissue. The left lateral fissure, complete, between
the left (lat.) and left mesial lobes (shown in diagram)
measures 8 cm., and between its extremity and the dorsal
margin are 5 cm. of hepatic tissue. On this aspect we are
struck by the large relative size of the mesial or cystic
lobe to the right of the suspensory ligament, which
laterally measures 12 cm., while on the left it only equals
5.5 cm. Three portions of the cystic or mesial lobe are
described, viz., large right mesial, small left mesial, and
the insignificant intermediate mesial (lobus quadratus).
Only a remnant of the cystic or mesial fissure (i.e., between
the intermediate and left mesial lobes) is seen, and
measures 2 cm. To it the suspensory ligt. runs from the
inf. v. cava. Anteriorally it becomes part of the gall
bladder cleft, which is 2.5 cm. long, and .5 cm. laterally.
The gall bladder is seen projecting on the two surfaces of
the liver. Between the cystic fissure and the gall bladder
cleft is a triangular projection, the remains on this aspect
of the intermediate mesial lobe (i.e., lobus quadratus).
It measures 3 cm. long, and 2.5 cm. laterally, i.e., it has
almost disappeared. The left mesial will fuse, as has
partially happened on the visceral surface, to the left
(lat.) lobe; and the suspensory ligt. will pass to the gall
bladder fissure with the final disappearance of the inter-
mediate mesial lobe.

(Specimen F.)

Diaphragmatic Surface. — The liver measures later-
ally 14 cm., and the right and left lateral fissures, i.e.,
between the mesial or cystic lobe and the right and left
(lateral) lobes have practically disappeared, being only
represented by fissures about 1.25 cm. long. Interest
chiefly centres round the ventral portion of the mesial
or cystic lobes. We distinguish firstly on the right the
cleft for the gall bladder, 4 cm. dorso-ventrally, and 2 cm.

Visceral Surface of Liver. Wombat. (Specimen F.)

B Gall Bladder, L Left Lateral Lobe, R Right Lateral Lobe,
IM Intermediate Mesial or Cystic Lobe. LM Left Cystic Lobe.
RM Right Cystic Lobe.

WOMBAT.

laterally. To the left of this two portions are seen, which
are continuous on the visceral surface, but are separated
on this aspect by a partly fibrous depression or groove.
These represent the intermediate cystic or mesial lobe.
To the left of these two parts another short fissure is seen
-the intermediate mesial or cystic fissure. Between the
dorsal extremity of this and the inf. v. cava runs the sus-
pensory ligt. Between this fissure and the remnant of
the left lat. fissure is a small fiat portion — the remains of
the left mesial or cystic portion of the tripartite cystic
lobe. It is here part of the left (lat.) lobe, and the inter-
mediate mesial portions are really left mesial. As re-
gards these two intermediate portions it would appear
that the anterior part (2 cm. long, and 1.25 cm. laterally)
is atrophying and separating off — the lower part (2 cm.
long, and 1.75 cm. laterally) corresponding to the human
lobus quadratus, i.e., between the suspensory ligt. and the
gall bladder cleft. With subsequent atrophy of this por-
tion the gall bladder cleft would be connected with the
suspensory ligt. In this direction evolution is trending,
and without doubt the atrophied lobus quadratus occa-
sionally described in connection with the human liver is
indicative of the trend.

Visceral Surface. — As on the diaphragmatic surface
the chief interest is centred round the mesial or cystic
lobe. Here the lower parts of the left mesial and inter-
mediate have become incorporated in the left (lat.) lobe.
Ventrally, the remains of the left mesial, 2.5 cm. long, and
1.5 cm. laterally, is seen, and in spite of a depression on
this aspect and the slight Assuring on the ventral edge it
has become incorporated into the left (lat.) lobe. So that
as a distinctive portion the left mesial or cystic lobe has
disappeared, having become incorporated in the left lat.
lobe. The intermediate lobe (now the left mesial or
cystic) is separated on the left side by a narrow cleft or

OESOPHAGUS

DCSCENOIHC DUOO

r/KEo ColonA pouches

ROOT or MESEHTCRY,

MESENTERY

The Gastro-Intestinal Tract of Wombat.

WOMBAT.

fissure ventrally, and a depression dorsally. To the cleft,
as stated, runs on the diaphragmatic surface the suspen-
sory light. The cleft, or fissure, and the depression repre-
sent the mesial or cystic fissure of the tripartite lobe. The
depression, or groove, does not run, however, to the portal
fissure, i.e., to portal vein, since the dorsal part of the
intermediate has, with the left mesial, joined the left
(lat.) lobe. The elongated remaining intermediate lobe
shows constrictions indicative of atrophy. With atrophy
of the narrow ventral portion a "lobus quadratus" would
be left, which also shows a fissure, so that great instabil-
ity is characteristic of the intermediate mesial and left
mesial lobes. The intermediate cvstic (now left cvstic or
mesial) is separated from the right mesial or cystic by the
cleft for the gall bladder, and a well defined fissure for
the cvstic duct.

Portal Vein. — At the portal interval the width of the
portal vein was 4 cm. Dorsal to it lay the cystic duct.
This corresponded to the division of the vein — seen from
the interior — into two main parts. From" the left,
branches passed to the right (lat.) lobe and intermediate
lobe, and from the right to the right mesial or cystic, and
to the right (lat.) lobe. The two circulations were dis-
tinctive.

f i r,r>

LIVER OF KOALA.

(PHASCOLARCTOS CINEREUS.)

Diaphragmatic Surface. — Three lobes are recognised
on this aspect, viz., large mesial or cystic, and the right
and left lateral lobes.

Right Lateral Lobe. — This is much smaller than the
left lateral — having a greatest length of 9.5 cm., and width
(laterally) 6 cm. — and is prolonged downwards into the
lumbar region as a pointed extremity. It presents one or
several fissures on this aspect. At the basal or attached
portion of its inner or left margin we see the hepatic re-
lationship of the inf. v. cava, 2 cm. long, the wall of which
is usually distinguishable throughout, though in some
specimens strands of hepatic tissue may partly occlude
this. A portion of the spigelian lobe is seen to the left of
the vein. This lobe is separated from the mesial or cystic
by a fissure — right lateral — which may extend to the
left almost as far as the inf. v. cava. On the other hand,
the fissure may extend internally only for 3.5 cm., while
between this and the vena cava is liver tissue for 3 cm.
In other words, the right lobe and the mesial may be one,
apart from an interval of 3.5 cm. The exit of the vena
cava practically corresponds to the point of convergence
of all three hepatic lobes.

Mesial or C fistic Lobe is the largest of the three lobes,
and in one specimen, where the right lateral lobe was well
separated from the cystic, it measures 18 cm. dorso-ven-
trally, and 14 cm. laterally. It presents three divisions,
viz., a large right portion — small intermediate — and a
left portion, usually mesial in size, between the two, al-

Diaphragmatic Surface of Liver. Koala.

B Gall Bladder Cleft, RM Right Mesial or Cystic Lobe, IM Inter-
mediate Cystic Lobe, LM Left Cystic Lobe, F Suspensory Liga-
ment, L Left Lateral Lobe, R Right Lateral Lobe, E Cleft for
Oesophagus. S Spigelian Lobe, V Inf. Vena Cava.

KOALA.

though occasionally the left lobe is the smallest of all.
Along its right edge numerous small fissures may be ob-
served, and the intermediate lobe may be partly divided
into two by a fissure. Between the large and intermedi-
ate lobes a cleft is seen, where the gall bladder is described
dorsally. Anteriorally this cleft measures 2.5 cm. in
width, while posteriorally it narrows — its length ventro-
dorsally is 5 cm. A well defined fissure separates the in-
termediate portion of the mesial lobe from the left por-
tion. Traced from the back of the left portion at the
inf. v. cava towards the posterior extremity of this fis-
sure, along the right of which it may be traced for 1 cm.,
is the mesial or suspensory ligament. It is attached above
to the diaphragm, and the length of its hepatic attachment
is 3.5 cm. The cystic or mesial lobe is well separated
from the left lateral lobe by a fissure extending dorsally
to within a short distance of the post hepatic surface.

Left Lateral Lobe. — This may measure dorso-ven-
trallv 14 cm., width laterally 8 cm., so that it is much
larger than the right lateral lobe. Its left margin is fre-
quently fissured. On the inner or right margin is the
concavity for the oesophagus, on its way to the stomach.

Diaphragmatic Attachments. — The dorsal half of the
left lateral, and of the inner and dorsal part of the right
lateral are closely attached to the tendinous portion of the
diaphragm. In addition, certain suspensory folds or
bands may be recognized.

(1) Mesial described above.

(2) Right lateral, from the diaphragmatic aspect

of the right cystic and adjacent right lateral
lobe.

(3) Left lateral (one or two), from the diaphrag-

matic aspect of the left lateral lobe.
All these go to the tendinous part of the diaphragm.

IM.

Visceral Surface of Liver. Koala.

B Gall Bladder. IM Intermediate Mesial Lobe, LM Left Mesial
Lobe. RM Right Mesial Lobe. L Left Lateral Lobe, R Right
Lateral Lobe. C Caudate Lobe, S Spigelian Lobe. V Inf. Vena
Cava. P Portal Vein with Duct and Artery.

KOALA.

Visceral Surface. — As on the diaphragmatic surface,
we can recognize three divisions, viz., right, mesial, and
left, but are struck with the large amount of Assuring,
giving rise to divisions scarcely, however, in many cases,
deserving the names of lobules. This feature, which at
first sight makes a description of this aspect appear dif-
ficult, is much more common in some varieties than in
others.

Left Lateral Lobe. — This is separated from the
mesial lobe by the left lateral fissure, which dorsallv may
reach the inf. v. cava. It is usually smooth, although,
as stated, the ventral edge may be fissured. This is asso-
ciated possibly with rib pressure, as this lobe reaches to
the left hypochrondrium, and the dorsum is usually in-
dented by the ribs. It is characterized by the presence
on its dorso-inner side of a somewhat quadrilateral pro-
jection, which stands out for 1.5 cm., and the length of
which is I cm. — at the dorsal aspect of this the portal
vein is seen. This projection, which lies parallel with a
somewhat similar projection of the left cystic lobe, forms
with it the ventral boundary of the portal interval, while
the dorsal boundary is formed by the right lateral and spi-
gelian lobes. These two projections come into relation
with the lesser curve of the stomach, dipping into the de-
pression or interval between the left or cardiac, and the
right or pyloric, portions of that organ. They lie ventral
to the lesser omentum, behind which is the lobus spigelii,
and may be regarded as accommodation effects. Owing
to its relationship to the fundus of the stomach the vis-
ceral surface of the left lateral lobe is concave.

The oesophagus passes clown in the concavity on the
inner margin, and from the oesophagus along the portal
interval passes the lesser omentum (gastro-hepatic),
which becomes continuous on the right with the meso-
duodenum. It is worthy of note that ventral and lateral

KOALA.

peritoneal bands are noted passing from the region of the
lesser curvature of the stomach to the under surface of
the left lateral lobe. These are ventral to the lesser
omentum, are more developed in some specimens than in
others — and may even approach the ventral border.

Mesial or Cystic Lobe. — As on the diaphragmatic
aspect, three divisions of the mesial lobe are noted — the
right being the largest, and the intermediate portion the
smallest. Occasionally, however, the left may be smaller
than the intermediate portion. The Assuring and lobu-
lations on this surface of the liver are seen to be charac-
teristic of the mesial and right lateral lobes. The left
division of the mesial lobe is usually demonstrable from
this aspect, but it may be almost completely hidden by
the extension to the right of the left lateral lobe. This
portion is frequently fissured ventrally, and posterior-
ally it narrows, presenting a projection lying parallel
with the somewhat similar projections of the left lateral
lobe. The left lateral fissure separates the mesial from
the left lateral lobe, and it may extend to the inf. vena
cava dorsally. Between the left cystic projection and the
dorso-int. part of the right cystic is the dorsal part of
groove for the cystic duct. The small intermediate por-
tion of the cystic lobe is frequently divided into two
lobules by a fissure. On its left is the fissure correspond-
ing dorsally to the suspensory ligt., and separating from it
the left part of the cystic lobe, and on its right it is hol-
lowed, forming part of the cleft lodging the gall bladder.
Dorsally on this lobe we notice a sharp pointed projec-
tion, and between this and a projection on the right cystic
is the commencement of the groove in which the cystic-
duct is lodged. The right or large portion of the mesial or
cystic lobe presents abundant Assuring and lobulation. It
is separated from the right lateral lobe by the right lat.
fissure, which is well defined on this face. The Assuring

KOALA.

is simplified by a description of the right and left edges.
The right margin may be devoid of Assuring — we may see
one well defined fissure practically separating this part
into two divisions, or we may see a series of small parallel
fissures in the lower half separating off small lobules.
Along the left, or gall bladder edge, Assuring is always
present. The fissures vary from four to six, and usually
three to five lobules are present, forming the right boun-
dary of the gall bladder and the cystic duct. Dorso-internal
it also forms part of the boundary of the portal interval.
Tims on its inner side, ventrally, it is separated from the
middle cystic by the cleft for the gall bladder and by the
proximal part of the depressed groove for the cystic duct,
and from the left cystic by the dorsal part of the depressed
groove for the cystic duct. Towards its outer or right
margin is a groove for the proximal colon.

Kiy lit Lateral Lobe. — This is characterized in all
cases by its Assuring and lobulation. It is prolongated to
a somewhat pointed extremity, and is hollowed below for
the reception of the kidney. Like the right cystic, the
main Assuring and lobulation are on the inner or left
margin, and the right outer margin may present fissures,
or be devoid. I have counted no fewer than eight lobules
on the inner side, and of the lobules two are well defined.
The upper of these two forms part of the boundary of the
portal fissure, and the lower forms a somewhat mobile
projection on the mesial part of the surface, and is fcta
caudate lobe. The caudate lobe takes part below in the
formation of the concavity for the reception of the kidney
and is prolonged obliquely inward as the somewhat fiat-
tenecl small Spigelian lobe. Between the two ventrally is
a groove for the passage of portal vein, artery, and duct,
and dorsally is the inf. v. cava, the hepatic relationship of
which is not seen on this aspect of the liver. The Spigelian
lobe, which measures 2.5 cm. laterally and 1.5 cm. greatest

Biliary axd Portal Systems. Liyer. Koala.

H Stomach. P Pancreatic Duct, D Duodenum, N Duod.-Intest.
Flexure. C Caudate Lobe, R Right Lateral Lobe, L Left Lateral
Lobe, RM Right Mesial or Cystic Lube. IM Intermediate Mesial
Lobe. LM Left Mesial Lobe.

KOALA.

width, lies behind the lesser omentum, and on the inner or
left side is the oesophagus as it lies in the concavity on the
inner margin of the left lobe. The right lateral lobe may
project beneath the ventral aspect of the right cystic or
be wholly distinct from it. Important relations of the
inner part of the ventral surface of the right lateral lobe
are the right portion of the stomach and the descending
pole of the duodenum, while in a groove near the right
margin is the proximal colon. Unlike Macropus, the liver
of the Koala extends across the upper abdomen from side
to side, being found in the epigastric and right and left
hypochondriac regions.

The Gall Bladder and Ducts. — The gall bladder is an
elongated sac placed in the cleft of the cystic or mesial
lobe, between the large right and the intermediate portions,
both of which are hollowed for its reception, and it is seen
both on the dorsal and ventral surfaces. It may project
bevond the ventral margin of the liver. It is more mobile
than the human gall bladder, since its ventral two-thirds
are completely invested by peritoneum, but usually the
dorsal third is more fixed, being only partly invested
with that structure and held in relationship with the
adjacent liver. It measures about 5.7 cm. dorso-ventrally
and 2.5 cm. across when moderately distended. In some
eases a cervix may be noted, but in others the cvstie duct
would appear to arise directly from the sac.

Cystic Duct. — This is lodged in a depressed groove
between the inner side of the large right portion of the
cystic lobe, and the dorso-internal portions of the inter-
mediate and left portions of the cystic lobe on the left, and
it may be necessary to remove parts of these to expose the
duet and the dorsal portion of the gall bladder. The duct
is closely related to the liver, being invested by peritoneum
on the ventral and lateral surfaces only, and in a well

i •>

KOALA.

developed specimen may reach 5 cm. in length. At the
portal interval, which really corresponds to a space
between the three main divisions of the liver the cystic
duct is joined by two hepatic ducts and becomes the com-
mon bile duct.

Hepatic Ducts. — On the left side the left hepatic
trunk is formed by the junction of 2 main branches, one
from the intermediate and left cystic, and the other from
the left lateral lobe. The right hepatic trunk, which is the
more proximal, receives branches from the right c^ystic
and right lateral lobe.

The Common Bile Duct passes down to the duode-
num, lying in a groove with the artery and portal vein at
the junction of the caudate and spigelian lobes, the portal
vein being dorsal to the duct as in the human liver. It
runs at first in the right extremity of the lesser omentum,
being related to pancreatic tissue, and finally enters the
meso-duodenum. In this Marsupial the lesser omentum is
definable though continuous with the meso-duodenum.
The descending duodenum can be lifted from the right
kidney and right lateral lobe of the liver, but the meso-
duodenum is short and the right part of the pancreas is
relatively fixed, and so a definition is made at the common
duct, artery, and vein, between the meso-duodenum and
lesser omentum. The length of the common duct is about
5 cm., and it terminates in the descending pole of the duo-
denum 4-5 cm. from the pyloric sphincter. There may or
may not be a slight dilatation before it terminates. Un-
like the monotremes and certain of the Marsupials, the
pancreatic duct opens into the duodenum independently
of the common bile duct.

GASTRIC Clano
MESIAL rOLO
DUODENUM

OESOPHAGUS

f>7 r/tox colon

I LCD CaZCAC
JUNCTION

GT OMENTUM
ROOT or MESENTERY

OUOOENAL. FOSSA

a o» Distal colon

MESOCOLON

The Gastro-Intesiinai. Tract in Koala.

KOALA.

Pancreatic Duct. — This usually forms a loop on the
right side, passing first down with the duodenum and then
up to the left towards the spleen. For its terminal 2 cm.
the pancreatic duct dilates into a sac measuring 1 cm.
across. Dorsal to this lies the common bile duct in close
relation with the wall, so that the most careful dissection
is necessary to separate them. A probe passed through
the common bile duct, however, shows its distinction from
the pancreatic sac. On reaching the wall of the duodenum
the pancreatic dilatation narrows and runs like the bile
duct obliquely through the wall of gut. They open separ-
ately into the interior. These openings are noted at the
summit of a papillary projection. This may occasionally
be absent and the openings only detected after the passage
of fine probes. The common duct is nearly three times the
size of the pancreatic duct before the dilatation of the
latter takes place. The pancreatic duct measures about
13-14 cm. long, and instead of forming a loop on the right
it may describe an almost straight course to the left,
receiving a well-defined branch from the duodenal portion
of the pancreas. This joins the main trunk .5 cm. before
the dilatation is reached.

Pancreas. — On the right side a well-defined vertical
process is seen, which may be regarded as the head of the
pancreas. Its width in a big specimen was 2.5 cm. It
does not fill the duodenal loop, though reaching below
almost to its extremity. It is placed in the dorsal part
of the meso-duodenum in relation with the ascending
pole of the duodenum, and is less mobile than the duo-
denal loop. The important feature is that the pancreas
on the right side is becoming dorsally fixed and the meso-
duodenum is shortening, although the duodenum can be
raised off the right lateral lobe of liver and right kidney,

KOALA.

It is traced upwards as an elongated process in relation
with the pancreatic and common ducts towards the liver,
so that it conies in relation with the lesser omentum.
Traced to the left it narrows to about 1.5 cm., lying in
close relation to the dorsal abdominal wall above the duod-
intest. junction, and is traced to the left of the distal colon
and its mesocolon lying just above the left adrenal gland.
It then enters the dorsal wall of the lesser sac. On reach-
ing the spleen, which is suspended on the great omentum,
it widens out, forming a piece which measures 5 cm. long
and 3 cm. wide, in a well-developed specimen. The upper
part of this is related to the body and beginning of anterior
thin elongated process, while the lower part is in relation
with the short broad left posterior process, beyond which
it usually extends. As the lieno-mesocolic fold is absent,
this latter process of spleen and pancreatic tissue related
to it might be regarded as related to the lesser sac being
swung on the great omentum. The pancreas may form
a tongue-shaped process extending 3 cm. beyond the con-
fines of the spleen. To sum up, the chief relation of the
pancreas is to the short left process and the lower part of
the body, of spleen, the upper half of the body and the
light elongated omental process being practically devoid.

Portal Vein. — Five main branches are usually to be
distinguished. Proximally we notice two, one on each
side — the left sending branches to the left cvstic or mesial
and left lateral lobes, and the right branches to the right
lateral lobes. More distally a branch is sent on the right
to the right mesial or cvstic. The vein finally terminates
in two branches, one passing to the right cystic or mesial,
and the other to the intermediate cvstic lobe.

LIVER OF TASMANIAN DEVIL

(SARCOPHILUS URSINUS.)

Diaphragmatic Surface. — Viewed from this aspect,
the liver may present three main lobes or divisions, viz.,
mesial or eystie, right lateral, and left lateral. In some
specimens, however, the right and cystic lobes form a
single lobe, so that the liver consists of two main divisions
only.

Left Lateral Lobe is larger than the right lateral, and
usually projects well forward, forming part of the ventral
border of the liver. Occasionally it does not project so
far forwards, and practically the whole of the ventral
border is formed by the anterior edge of the mesial lobe.
This is specially noted in the two-lobed liver. In a well
defined case the left lobe measured 14 cm. from before
backwards, and 12 cm. laterally. In all cases this lobe is
well defined by a left lateral fissure — usually traced inter-
nally to the inf. v. cava — from the mesial or eystie lobe.
On the inner or right margin dorsally is the concavity for
the passage of the oesophagus.

Mesial or ('//stir Lobe. — This presents a well marked
cleft for the gall bladder, and by this means two portions
may be distinguished, viz., right and left mesial, and either
of these may be the larger. Occasionally specimens may
show subdivisions of either right or left portions. Thus
in an adult male specimen I found the right and left por-
tions separated by the cleft and fissure for the gall blad-
der, and, in addition, two well defined lateral lobes were
noted (i.e., four cystic lobes in all), and these were sep-
arated by well defined fissures. On the right portion one

Diaphragmatic Surface of Liver. Tasmanian Devil.

(Specimen 1.)

B Ciall Bladder Cleft, LF Left Lateral Fissure, F Attachments to
Diaphragm. V Inf. Vena Cava. E Cleft for Oesophagus.
LM Left Mesial Lobe. RM Right Mesial Lobe, L Left Lateral
Lobe, R Right Lateral Lobe.

TASMANIAN DEVIL.

or several fissures may be met with, giving rise to several
small lobules. Apart from the division formed by the gall
bladder cleft the evstie or mesial lobe may be a single
mass. As a rule, however, the cleft for the bladder is pro-
longed as a fissure dorsally. In one specimen the cystic
lobe laterally measured 14 cm. and dorso-ventrallv 11 cm.,
and the cleft measured 8 cm. dorso-ventrally and 2 cm.
laterally, and was prolonged dorsally as a fissure for 3.75
em. In another the cleft was 3 cm. dorso-ventrally as
well as laterally and without fissure. The gall bladder is
well seen in the cleft on this aspect, and at the back of the
right portion of the cystic lobe corresponding to the inner
extremities of the right and left laterals we see the inf.
v. cava emerging from the liver before passing through
the diaphragm.

Bight- Lateral Lobe. — This is the smallest of the three
lobes. It is prolonged as a pointed extremity into the
lumbar region above and external to the right kidney,
and is hollowed below for the reception of the caudal
pole of the latter. Usually the right lateral lobe is sep-
arated from the mesial by a fissure prolonged obliquely
inwards towards the inf. v. cava. In others, beyond a
slight lateral fissure, there may be no separation, — the
mesial and right laterals forming practically one lobe.
In others, with the slight Assuring we may find an irregu-
lar depression denoting the site of the old fissure. Thus
in the Tasmanian Devil we may have — seen from this
aspect — a liver consisting of only two lobes, viz., left
lateral and right lobe, the latter being formed by the
union of or a failure to separate of the mesial or cystic
lobe and the right lateral. The greatest length of a free
right lobe laterally is 8 cm., and dorso-ventrally 11 em.
Occasionallv the right lobe may be subdivided by a well
marked fissure. In some, small fissurings are met with
on the right edge.
Gl 82

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TASMANIAN DEVIL.

Diaphragmatic Attachments. — The liver is not, as a
rule, closely bound dorsally to the diaphragm. Mesially
we notice what we may regard as a suspensory ligament
— a fine peritoneal fold attached above to the muscular
and tendinous portion of the diaphragm, and below to the
left portion of the cystic lobe, passing obliquely from the
left of the gall bladder fissure to the inf. vena cava and
the dorsal margin, and may reach the lesser omentum at
the oesophageal concavity. A small fissure may be noted on
the left cystic lobe directed to the left, in which the ventral
part of the suspensory ligament is lodged. In another
there was a small fissure on the middle of the left edge of
the gall bladder cleft, and the gall bladder fissure curved
out to the left for about 1.5 cm., and to this expansion the
suspensory ligament was attached. In the 4-lobed cystic
specimen the suspensory ligament runs from the back of
the lobe on the immediate left of the cystic cleft, i.e., left
mesial cystic. In addition, we notice a series of fine lateral
suspensory folds, i.e., from the right lateral and right
cystic dorsally to the tendinous part of the diaphragm,
and also 3 or 4 fine suspensory folds from the left cystic
and left lateral dorsally to the tendinous diaphragm, but
none of these pass as far forwards as the mesial suspen-
sorv fold.

Visceral Surface. — As variations are met with in the
liver of this Marsupial it will be necessary to present two
descriptions of this.

No. 1. — Here on the diaphragmatic aspect right
lateral and cystic lobes are practically one. Small variety.
Two-lobed liver.

Left Lateral Lobe. — This is separated from the rest
of the liver by the left lateral fissure. It is smooth, and
does not project forwards to form part of the anterior

TASMANIAN DEVIL.

border. On its inner or right side are one, sometimes two
projections — the lower of which when two are present
is the larger. The projection is grooved, overlapping the
abdominal oesophagus before it reaches the stomach, and
on its inner side is the portal interval. Dorsal to the pro-
jection along the inner margin, we see a concavity for
the passage of the oesophagus.

Mesial or Cystic Lobe. — Although the right lateral
and mesial lobes are practically one, yet a distinction can
be made between the two by the curved prolongation of
the right to the lumbar region, and a depression between
the two. It forms the anterior or ventral margin of the
liver. On this aspect the cystic lobe presents three por-
tions, viz., a large comparatively smooth left portion, on
the inner or light margin of which one or two fissures
and an upper and lower projection are noted, while on
the right we have two parts usually of almost equal size
separated by a fissure which may be distinct or not, and
so the cvstic lobe may be said to consist of a left, inter-
mediate, and right portions. In one the left lobe was sub-
divided also into two portions. Between the left and in-
termediate portions is the gap for the gall bladder, the
width of which at the ventral margin is 2 cm., and these
portions are hollowed for its reception. The intermediate
and right portions are characterised by their Assuring
and lobulation, and I have counted here no fewer than 11
lobules Between the two parts of the right portion on one
side and the left portion on the other we see the cystic
duct, which is joined by the hepatic ducts at the portal
interval. This interval is placed between the lower pro-
jection of the left cystic and the inner part of the left
lateral lobes on the left side and the internal part of right
cystic and right lateral on the right side.

Visceral Surface of Liver. Tasmania^ Devil.

( Specimen 1.)

B Gall Bladder, LM Left Mesial or Cystic Lobe, RM Right Mesial
Lobe. L Left Lateral Lobe, R Right Lateral Lobe. C Caudate
Lobe. S Spigelian Lobe. V Inf. Vena Cava.

TASMANIA** DEVIL.

Right Lateral Lobe. — Though this is described as a
separate lobe it really, as stated, is joined with the cystic
lobe — the whole forming a large right lobe. It is charac-
terized by its Assuring' and lobulation, which is even met
with on the renal surface. It is concave below for the
reception of the right kidney, and is prolonged external
to the kidney as a pointed extremity. Projecting on this
right lobe, and forming the ventral part of the concavity
for the upper pole of the kidney is the well defined lobus
caudatus, 3 cm. laterally, and 2 cm. dorso-ventrallv. This
is prolonged to the left as a somewhat flattened, though
pointed, lobus spigelii, which is traced ventral to the left
lobe. Between the caudate and spigelian lobes is a well
defined depression, and here, passing down between the
two, we have the vein, artery, and duct. Dorsal to the
inner extremity of the lobus caudatus is the entrance of
the inf. v. cava. As regards its hepatic relationship it is
hidden — only the entrance and exit, as described, being-
visible. The hepatic relationship of the vein measures
4 cm.

No. 2. — Here on the diaphragmatic aspect the three
lobes of the liver, viz., right and left lateral, and mesial
or cystic, are distinct. Large variety. Three-lobed liver.

Left Lateral Lobe. — This not only forms in the left
hypochrondrium the left margin, but also takes place in
the formation of the ventral margin, and ma}7 extend in
the epigastric region to the right of the ensiform cartilage.
It is smooth, not being characterized by Assuring and
lobulation, and presents a projection on the inner side,
which forms part of the left boundary of the portal in-
terval, or fissure. It tends to occlude the greater portion
of the left part of the cystic lobe, and dorsal to the pro-
jection presents on the inner side a concavity for the
oesophagus. It is separated from the left part of the
cvstic lobe by the well defined left lateral fissure, and is
concave ventrally for the fundus of the stomach.

LM.

Vjsckral Surface of Liver. Tasmania?* Devil.

(Specimen 2.)

15 Gall Bladder, LM Left Mesial or Cystic Lobe. RM Right Mesial
Lobe. T. Left Lateral Lobe. R Right Lateral Lobe. C Caudate
Lobe. S Spigelian Lobe. V Inf. Vena Cava.

TASMANIAN DEVIL.

Mesial or Cystic Lobe is divided into two parts by
the cleft and fissure for the (Jail Bladder. The left of
these is, as stated, largely hidden by the left lateral lobe,
and the dorsal part of the right is hidden by the right
lateral lobe. Either the right or left may be the larger
of the two portions. The Gall Bladder tits into con-
cavities in the walls of the right and left portions, form-
ing the margins of the cleft. The left part of the cystic
lobe ventrally is smooth, but dorsally, i.e., in the part
hidden by the left lat. lobe it is lobulated and fissured, and
on its inner, or right, extremity three fissures are usually
seen, so that an upper or ventral — mesial — and lower, or
dorsal portions, are described; the two upper forming the
left boundary of the gall bladder cleft and cystic duct,
and the lower partly of the cystic duct and partly the
boundary of the portal fissure. The right portion shows
as a rule no Assuring on the right margin, but is lobulated
and fissured on the inner or left side, forming the right
boundary of the gall bladder cleft and cystic duct fissure.
It is separated by a well defined fissure from the right
lateral lobe. It is worthy of note that this right-sided
Assuring is not so marked in the three lobed livers as in
those where the cystic and right lateral are one. This
suggests that a big fissure or interval and separation of
the lobes allows of elasticity. With closure of the fissure
and union we have numerous lobules and fissures.

Right Latent! Lobe. — By means of a pointed ex-
tremity this lobe prolongs the liver down and to the right
into the lumbar region, external to the right kidney. Fis-
snring and lobulation are characteristic of this part. It
is noticeable that these, however, are practically confined
to the upper and intermediate divisions — the caudate lobe
being devoid of fissuring. Three main divisions may be
recognized — an upper small division — an intermediate
prolonged down and t<» the right — and a more mobile in-

Biliary and Portal Systems. Liver. Tasmanian Devil.

H Stomach, D Pyloric Sphincter, P Pancreatic Duct. C Caudate
Lobe, !< Right Lateral Lobe, L Left Lateral Lobe. LM Left
Mesial Lobe. KM Right Mesial Lobe.

TASMANIAN DEVIL.

ternal portion — the lobus caudatus — prolonged to the left,
as the small somewhat flattened lobus spigelii. Between
the caudate and spigelian lobes is a well marked depres-
sion, ventral to which pass the portal vein — artery — and
common duct. Both the intermediate division and the
lobus caudatus form the concavity below for the recep-
tion of the kidney Passing up at the inner and back part
of the lobus caudatus is the inf. v. cava. Its hepatic re-
lationship, which is similar to the preceding, measures ()
cm. The (esophagus, on its way to the stomach, passes
between the left surface of the spigelian lobe and the
concavity of the left lat. lobe. The portal interval corre-
sponds to the interval between the ventro-internal por-
tions of the right and left lateral lobes. Whilst the
fundus of the stomach is, as stated, related to the left lat.
lobe, the pyloric part of the stomach, and commencement
of the intestine, slightly below the duct entrance, are re-
lated to the right cystic and right lateral lobes. In the
Tasmanian Devil the liver is found in the epigastric and
right and left hypochondriac regions, even extending to
the right lumbar region.

Gall Bladder and Z^c/.s.— The Gall Bladder may be
described as a conical or ovoid sac, placed in the gall
bladder cleft in the mesial or cystic lobe Where the cystic
lobe is divided into two parts it lies between the two, but
when into three it lies between the left and intermediate
lobes. It may or may not project at the anterior edge.
The cleft involves the whole thickness of the lobe, and the
surfaces forming the cleft are concave. This is more
marked in some than in others, and it may be necessary
sometimes to divaricate the divisions to see the bladder.
Although for the most part completely invested by peri-
toneum, it is held by peritoneal bands to the lateral boun-
daries of the cleft. These adhesions rarely extend further

TASMANIAN DEVI L.

forward than the middle of the bladder. The posterior
1 5th is closely bound to the liver substance, so that it
can only be regarded as invested by peritoneum on the
under surface and sides. The (Jail Bladder measures
3.5 cm. dorso-ventrally, and laterally, when collapsed, 2
cm.

Cystic Duct. — This measures about 2 cm. in length,
and runs in a depression or channel between the left part
ot the cystic on one side, and the fissured and lobulated
inner part of the right division on" the other. It is joined
by four main hepatic ducts from the liver, and becomes
the common bile duct. The portal interval, where this
union takes place, is situated between the ventro-inner
projection of the left lat. lobe, the ventro-inner part of
the right lat. lobe, and the dorso-inner parts of the right
and left cystic lobes. To see the junction of the ducts it
may be necessary to detach portions of the right or left
lobes.

Hepatic Ducts.— On the left side we notice a smaller
A'entral branch from the left mesial lobe, and a larger
dorsal branch from the left lat. lobe. On the right side
we note a small branch vent rally from the right mesial,
or from the intermediate mesial or cystic and ventral part
of the right mesial, and a dorsal branch from the right
lateral and caudate lobes, which receives, near its termina-
tion, a branch from the lower part of the right cystic, or
right part of the mesial.

The Common Bile Duct, with the portal vein dorsally,
and the artery dextral, passes down on the right of the
lesser omentum, lying at first in the interval between the
spigelian and caudate lobes (the inf. v. cava lying dor-
sally behind the inner part of the caudate), and, sur-

TASMAX1AN DEVIL.

rounded by pancreatic tissue which is traceable up to the
portal interval, it finally opens into the intestine about 3
cm. beyond the pyloric sphincter. The portion of gut
between the pyloric sphincter and the duct entrance is
dilated, and although there is no duodenal loop here, as
in the other Marsupials, might be regarded as duodenal,
since I have found Brunner's glands. The wall of this
dilated part of intestine has a firm feel compared with the
intestine beyond the duct entrance, and it is interesting to
note the great vascularity of the intestine after the bile
duct has entered. The duct terminates by an easily de-
fined pin-hole opening. I have not found it associated
with any papillary projection. The total length of the
common duct, i.e., from the portal interval to intestine,
equals 9 cm. The pancreatic duct joins the common duct
5 cm. from its termination, i.e., comparatively near the
liver, and the tube is easily defined. After the entrance
of the pancreatic duct the common duct dilates, and the
circumference of the last 2 cm. is more than double that
of the common bile duct. The pancreatic duct is traced
out as a single duct towards the spleen. It is easily traced
in the pancreatic tissue, and receives branches in its
course. On the left it receives a well defined branch from
the pancreas, on the left lateral (lieno-mesocolic) fold.

Lester Omentum. — In this Marsupial a distinction
between the dorsal mesentery, i.e., "meso-duodenum" and
lesser omentum, is made possible by the development of
a large Foramen Winslowii, which usually will admit the
thumb, and of which the portal vein, artery, and common
duct form the ventral boundary. The upper attachment
of the lesser omentum is short, and is traced from the
oesophageal concavity on the dorso-internal margin of
the left lobe to the portal interval.

TASMANIAN DEVIL.

Portal Vein. — Dorsally two main branches are given
off on each side — one to the left lateral lobe, and the other
to the right lateral, sending branch to the caudate and
spigelian lobes. Ventrally, it terminates in two branches,
one to the left mesial, and one to the right mesial lobes.

Pancreas. — Pancreatic tissue mav be traced alono-
the common clnct on the right extremity of the gastro-
hepatic omentum, up to the portal fissure. Only a rela-
tively small amount is found in the back part of the
dorsal mesentery, corresponding to the meso-duodenum.
I have never been able to trace it in relation to the duo-
denal wall and about the common duct after being joined
by the pancreatic duct, so that the amount in this animal
in the region of the intestine corresponding to the duo-
denal loop of other Marsupials may be regarded as insig-
nificant. The Tasmanian Devil has a well developed great
omentum, which runs from the pyloric region along the
great curve of the stomach. It is independent of the
dorsal mesentery, by which we mean meso-duodenum—
mesentery — and mesocolon, so that no portion of intestine
is included in the lesser sac. If we throw the great omen-
tum and stomach up on to the chest wall we see dorsally
about the root of the mesentery a well defined piece of
pancreas, from which strands are traced on to the great
omentum. Traced to the left of the mesenteric root, the
pancreas passes out to the spleen, but beyond sending
several processes on to the great omentum it is really out-
side the lesser sac, forming its lower boundary. In some
specimens no pancreas can be traced in relation to the
body or the right ant. process of the spleen; in others,
however, a piece may be found in the lesser sac related to
the body of the spleen, i.e., extending towards the fundus.
The main pancreatic tissue diffuses itself over the mem-

TASMAX1AX DEVIL.

brane (the lieno-mesocolic, or left lat. fold), extending
between the short left process of the spleen and the
dorsal wall close to the attachment of the meso-colon.
This membrane is nearly 10 cm. long, but pancreatic
tissue does not extend nearer than about 2 cm. to the pos-
terior, or dorsal attachment. The membrane is some-
what triangular in shape, extending above from the root
of the mesentery out along the lower part of the lesser
sac to the left posterior or dorsal short process of the
spleen, to which it is attached. This basal portion
measures about 5-6 cm. Its right margin is, as stated,
attached at dorsal wall to the left of the attachment of
the mesocolon, while the left margin is free.

LIVER OF NATIVE AUSTRALIAN CAT.

(DASYURUS VIVERRINUS.)

Here one is struck bv tlie small amount of
fusion that has taken place between the lobes, so that alto-
gether the liver lias a very primitive character. In a
specimen (adult) given me by Professor J. P. Hill, when
examined from the diaphragmatic surface, the three
primary lobes, viz., mesial and right and left (laterals)
were defined, and also the dorsal portion of the caudate
lobes. The mesial division was quite distinct from the
laterals, being but slightly attached dorsally at the inf.
v. cava. The right and left (laterals) lobes were only con-
nected dorsally by a narrow isthmus of hepatic tissue be-
tween the exit of the v. cava and the concavity for the
passage of the oesophagus on the dorsal margin.
Maximum Measurements. Laterally. Dorso-ventrally.

Right 2.25 em. . . 3 cm.

Left 4 , .. 4

Cystic or mesial 5 4

Chief interest, however, apart from the mobility,
centres round the cystic or mesial lobe. On this surface
there was a well defined cleft, anteriorally, for the gall
bladder, measuring 1.5 cm. long, and .75 cm. laterally At
the base or dorsal part of the cleft a small lobule is dif-
ferentiated, representing the intermediate mesial lobe.
It measures .75 cm., and .5 cm. across, and is bounded by
the gall bladder fissure on the right, and a depression on
the left, really representing the cystic or mesial fissure
of other Marsupials. Between it and the inf. v. cava
passes the suspensory ligament. Thus a right, left, and
intermediate mesial or cystic lobes could be distinguished.

97 h

Diaphragmatic and Visceral Surfaces of Liver.
Native Australian Cat.

B Gall Bladder, LM Left Mesial Lo'be, RM Right Mesial Lobe,
L Left Lateral Lobe. R Right Lateral Lobe, IM Intermediate
Mesial Lobe, C Caudate Lube. V Inf. Vena Cava. E Oesophagus.
ST Stomach.
HI 98

AUSTRALIAN CAT.

On Visceral Surface there was a division of the cystic
lobe into two practically equal lobes, viz., right and left
cystic, or mesial, by the gall bladder cleft, and a well
defined fissure for the cystic duct. The Left (lateral )
lobe is concave for the reception of the stomach, and on
this aspect of the right (lat.) lobe, the mobile caudate
lobe- — usually fissured above — is noted. It forms below,
with the right lobe, part of the concavity for the upper
pole of the kidney. At its dorso-inn'er part the entrance
of the inf. v. cava is noted, and the vein is hidden in its
hepatic relationship. There is a small lobus spigelii, and
between the two pass in a groove the portal vein, artery,
and bile duct.

In a specimen (see diagram) in the Hunterian
Museum, London, that had been in spirit for many years,
the primitive type of the lobulation was very marked,
and the separation of the liver into right and left portions
by the gall bladder and cystic and hepatic ducts was
evident macroscopically. The hepatic ducts were right
or left. Thus the left liver includes left mesial, left inter-
mediate, and left lateral lobes, and the right liver includes
right mesial, right lateral, and caudate and spigelian
lobes.

(a)

(B)

Diaphragmatic Surface of Liver.

(A) American Opossum. (B) Bandicoot.

B Gall Bladder and Cleft. V Inf. Vena Cava, LM Left Mesial Lobe,
KM Right Mesial Lobe. LM Intermediate Mesial Lobe. L Left
Lateral Lobe, R Right Lateral Lobe. S Spigelian Lube.

100

THE LIVER OF BANDICOOT.

(PERAMELIDAE.)

Through the kindness of Professor J. P. Hill I was
presented with a female N.S.W. Bandicoot. The liver is
characterized by its resemblance to that of Trichosurus.
When examined from the diaphragmatic surface a well
defined separation into three primary divisions is seen,
viz., right lateral, left lateral, and mesial or cystic. These
are separated by well defined and complete right and left
lateral fissures. Apart from the exit at the junction of
the three divisions dorsally, the inf. v. cava is not seen in
its hepatic relationship. Three portions of the mesial
or cystic division, whose lateral measurement is 6 cm.,
are defined, viz., right and left mesial, and intermediate.
The (smallest) left, and intermediate are separated by a
complete fissure — mesial, or cystic fissure — not, however,
extending as far dorsally, as the inf. v. cava — 1.25 cm.,
intervening. Between the right and intermediate por-
tions of the cystic is a well defined gap for the gall blad-
der, which is seen on this aspect, 2.5 cm. long, and 1 cm.
laterally. The gap is not prolonged dorsally as a fissure.
Between the mesial or cystic fissure and the exit of the
vena cava is the attachment of the suspensoiy ligament.

Visceral Surface. — The striking feature is the rela-
tively large size of the left lateral lobe, which occludes on
this aspect the intermediate and left cystic lobes, and its
edge may be traced on the right to the gall bladder. It
measures 3 cm. laterally, and 5 cm. dorso-ventrally, is

101

f-YLORlC SPHINCTER

TERMINATION OF
DUODENUM

POSITION OF
DUODENAL FOLD

Small, gut
on mesentery

GTOKENTUM

spleen

REMAINS OF1
MESIAL FOLD

'I LEFT LAT.F-QLO

MESOCOLON

COLON

The Gastro- Intestinal Tract of Bandicoot.

PYLORIC SPHINCTER

DUODENUM

MCSO DUODZNUM

Small got

TERMINATION O
DUODENUM

REMAINS OF
MESIAL FOLD

GREAT OMENTUM

DORSAL.
MESOQASTER

SPLEEN

left cat: fold
(lieno mesocolic)

DORSUM

MESOCOLON

mesentery

The Gastro-Intestinal Tract of American Opossi m.

102

BANDICOOT.

(hollow) concave below for the body of the stomach-
and dorsally is the narrow concavity for the passage of
the oesophagus. The three primary divisions are defined
as on the diaphragmatic surface, and also the three por-
tions of the mesial or cystic lobe — the right and inter-
mediate portions being separated by the gall bladder gap
and the curved well defined fissure for the cystic duct.
The right mesial or cystic portion is the largest of the
three. On this surface also we see in relation to the right
lobe the caudate and spigelian lobes, and the former is
well defined, and though distinct from the right lobe is
attached dorsally to it, and mainlv forms the concavitv
for the right kidney. The spigelian lobe is small. Be-
tween the spigelian and caudate portions is a sharp de-
pression, along which pass the portal vein, artery, and
duct, and at the dorso-inner part of the caudate lobe is the
hepatic entrance of the inf. v. cava. The right lobe is
the smallest of the three divisions of the liver, and the
caudate lobe, which cannot be lifted free from it as in
other Marsupials, is characterized by an elongated pro-
jection caudally towards the right kidney. The liver in
the adult Bandicoot measures laterally 10 cm., and the
inf. v. cava is not seen in its hepatic relationship.

103

LIVEh OF AUSTRALIAN PHALANGERS.

(TRICHOSURUS AND PSEUDOCHIRUS),

(1. ) Trichosurus. — • Diaphragmatic Surface. — The
liver in this Phalanger lies in the epigastric and right and
left hypochondriac region, and, as in the Platypus, there
is a well marked separation of the right lateral, left lateral,
and mesial lobes. The dextral margin is seen to be longer
than the sinistral, and the ventral than the dorsal.

Three features are to be noted, viz.: —

(a) The relatively small size of the right lat. lobe

compared with the left lat., and the cystic,
or mesial lobe.

(b) The gall bladder is somewhat dextrally placed

on the cystic lobe.

lobus eaudatus is seen on the dextro-dorsal
aspect of the right lat. lobe.
The liver measures dorso-ventrally 7 cm., and late-
rally 10 cm.

Mesial or Cystic Lobe. — This presents three divisions,
viz., right, intermediate, and left. Of these the right is
the smallest, and the intermediate the largest. Between
the intermediate and right portions is the cleft, 2 cm. long,
and the width, .75 cm. — sometimes fissured below — for the
gall bladder, extending from the dorsal to the ventral
surfaces, so that the gall bladder is seen on each aspect.
This lobe is separated from the right lateral by the right

104

Diaphragmatic Surface of Liver. Australian Phai.axc.er.

(A) Trichosurus. (B) Pseudochirus.

B Gall Bladder Cleft, L Left Lateral Lobe, R Right Lateral Lobe,
F Attachment to Diaphragm. V Inf. Vena Cava, E Gap for
Oesophagus, C Caudate Lobe, IM Intermediate Mesial Lobe,
LM Left Mesial Lobe, RM Right Mesial Lobe.

105

AUSTRALIAN PHALAXGERS.

lateral fissure, which, though directed towards the exit of
the inf. v. cava, does not reach it. It measures about 2.5
cm. It is also separated from the lateral lobe by the left
lat. fissure (3 cm. long), which dorsally reaches the inf.
vena cava. In addition a mesial or cystic fissure is noted
between the intermediate and left mesial portions (1.75
cm. long), directed dorsally towards the vena cava. The
mesial lobe measures 6.5 cm. laterally, and 5 cm. dorso-
ventrally, and is definitely separated from the lateral
lobes.

Left Lateral Lobe. — This measures 5 cm. laterally
and 4.5 cm. dorso-ventrally, and usually presents a small
fissure on its left margin. It forms, with the cystic lobe,
the ventral margin of the liver, and is broader dorsally
than ventrally. On its dorso-internal margin is a small
concavity for the transmission of the oesophagus, which
passes between it and the spigelian lobe.

Bif/I/t Lateral Lobe. — This measures 3 cm. laterally
and 3 cm. dorso-ventrally. and may present one or two
fissures on its dorsal margin. At its dorso-dextral mar-
gin the dorsal extremity of the caudate lobe is usually
seen.

Inf. v. Cava. — On this aspect of the liver at the point
of convergence of all the lobes the exit of the inf. v. cava
is seen. In its hepatic course it is neither seen dorsally
nor ventrally.

Diaphragmatic Attachments. — Dorsally the left late-
ral— mesial — and right lateral lobes have all a fine mem-
branous attachment to the tendinous diaphragm, and on
the left margin of the left cystic an extension forward is
seen, simulating a suspensory ligt., and passing out to the
muscular diaphragm above. The suspensory ligament
is attached above to the tendinous and muscular dia-

10fi

AUSTRALIAN PHALANGERS.

phragm, and below is attached to the intermediate cystic
lobe, just to the right of the cystic or mesial fissure ; and
passing dorsally from the fissure to the inf. v. cava it
serves with the fissure to define the left cystic from the
rest of the mesial lobe.

(2.) Pseudochirus. — Diaphragmatic Surf arc. — Here
the chief point is the encroachment ventrally of the left
lateral lobe, so that it forms the chief portion of the
ventral or anterior margin. The gall bladder is seen
dextrally, and we distinguish a large right margin and
smaller left. The three lobes are defined, viz., small right
lateral, large left lateral, and the mesial or cystic lobe,
with its three divisions. The dorsal part of the caudate
is also seen projecting. The hepatic course of the inf. v.
cava, as in Trichosurus, is not visible, only the exit being-
noted. Owing to its projection ventrally only a small
portion of the left lateral lobe is visible on this aspect.
The liver measures dorso- ventrally 9.5 cm., and laterally
9 cm.

(1.) Trichosurus. — Visceral Surface. — Here we
notice, as on the diaphragmatic surface, the relatively
small size of the right lateral lobe compared with the
mesial or left lat. lobe, and in one specimen the left lateral
lobe equalled 7 cm. in greatest length, which was double
that of the right lateral (including the caudate lobe).

Left Lateral Lobe. — Is frequently fissured about the
middle of its left margin, and may be prolonged as a
saddle-flap lobe over the ventral aspect of the stomach.
The left lateral fissure separating it from the mesial or
cystic lobe is traceable to the portal interval. Dorso-
internally is the concavity for the oesophagus, and pro-
jecting below the inner extremity is the spigelian lobe.
This lobe is related to the left or cardiac portion of the
stomach.

107

IM.

Visceral Surface of Liver. Trichosurus.

L Left Lateral Lo'be. R Right Lateral Lobe, IM Intermediate Mesial
Lobe, B Gall Bladder, RM Right Mesial Lobe. LM Left Mesial
Lobe. C Caudate Lobe. S Spigelian Lobe. V Inf. Vena Cava.

108

AUSTRALIAN PHALANGEKS.

Mesial or Cystic Lobe.— The three divisions are all
visible on this aspect, and the lobe is freely separable from
the right and left lateral lobes. The intermediate por-
tion, like the left lateral, may sometimes be prolonged as
a saddle-flap portion. The right lateral fissure, as well
as the mesial or cystic fissure between the intermediate
and left cystic portions, are traceable to the portal in-
terval, The right and left lat. fissures are complete
from the dorsum to ventrum, but the cystic fissure is only
partially through the substance. The gall bladder cleft
between the middle and right portions is well defined, and
the margins are hollowed out for the reception of the gall
bladder, and to further accommodate the latter a projec-
tion is thrown forwards on the inner side of the inter-
mediate portion, and between this and the right cystic is a
depression for the cystic duct.

Right Lat <ral Lobe. — Two main portions are seen-
the dorsal being the right lateral, and the ventral the
caudate. In the former Assuring is usually noted about
the middle and lower part. The caudal part forms, with
the lobus caudatus. the concavity for the upper part of
the right kidney.

The Caudate Lobe can be freely raised from the right
lateral. It presents three surfaces, viz., dorsal for the
right lateral — caudal for the kidney — and ventral for the
pyloric sphincter and beginning of the duodenum. It
measures 1.5 cm. dorso-ventrally, and 2.6 cm. lat.

Spigelian Lobe.--This is seen projecting from the
inner side of the right lat. lobe and the caudate, below the
left lat. lobe. It has a pointed extremity, is somewhat tri-
angular in shape, and measures 1.25 cm. long. It lies
dorsal to the lesser omentum. Passing in a depression
between the spigelian and caudate lobes are the common

109

LJ^

Visceral Surface of Liver. Pseudochirus.

W Dorsel Abdominal Wall, K Kidneys, C Caudate Lobe, S Spigelian
Lobe. I. Left Lateral Lobe. R Right Lateral Lobe. R (iall
Bladder. RM Right Mesial Lobe. IM Intermediate Mesial Lobe.
LM Left Mesial Lobe.

110

A USTK ALIAN PHALANGERS.

bile duct, artery, and portal vein, the former being ven-
tral, and the latter dorsal. The right part of the middle
cystic — right cystic — and the right lateral lobes corre-
spond to the left or pyloric part of the stomach. The
portal interval or hilum, where we see portal vein, com-
mon bile duct, and hepatic artery corresponds to an inter-
val between the dorsal part of the mesial lobes and the
inner extremitv of the right and left lateral lobes.

Inf. V. Cava. — This is not seen in its hepatic relation-
ship dorsally or ventrally, i.e., is hidden in hepatic tissue.
Its entrance is placed at the dorsal part of the inner ex-
tremity of the lobus caudatus.

Lesser Omentum (g astro-hepatic). — From the exit
of the inf. v. cava on the diaphragmatic aspect, where it is
continuous with the suspensory ligament, it passes ven-
trally at the concavity for the oesophagus on the dorso-
int. part of the left lateral lobe, and lies along the dorso-
int. part of this lobe, between it and the spigelian lobe,
being traced to the portal interval. A band is noted
ventral to the lesser omentum from the ventral surface of
the left lobe to the lesser curvature of the stomach corre-
sponding to the angle or bend between the pyloric or right
and cardiac or left portions.

(2.) Pseudochirus. — Visceral Surface. — Left Lateral
Lobe. — The important feature is the ventral pro-
jection of this lobe, and in a specimen, where the
lateral measurement of the liver was 7.5 cm., the left
lateral lobe was 5 cm. Dorsally the concavity is noted
for the oesophagus ; also one or two fissures on its ventral
margin, and some Assuring on its ventral surface. At the
inner margin, dorsally we see the spigelian lobe — a
pointed prolongation to the left of the caudate lobe —

111

AUSTRALIAN PHALANGERS.

slightly larger than in Trichosurus. The portal vein,
artery, and common dnct pass between the spigelian and
caudate lobes. The hepatic course of the inf. v. cava is
not seen.

Mesial or ('//stir Lobe. — The left cystic is completely
hidden by the left lateral, also the greater part of the
intermediate cystic, and partly the gall bladder cleft —
otherwise it is similar to Trichosurus.

Bi/jht Lateral Lobe. — On its dextral margin a small
fissure is noted. The lobus caudatus is proportionately
larger than in Trichosurus, and forms a greater part of
the concavity for the right kidney. In connection with
the lobus caudatus in both Trichosurus and Pseudochirus
the following points must be noted: —

(1.) Good development.

(2.) Comparative mobility.

(3.) Relation to the upper pole of the right kidney.

(4.) The inf. v. cava is not visible in its hepatic
relationship.

Gall Bladder and Ducts in Phalangers.

The ({all Bladder is dextrally placed, and is seen both
on the ventral and dorsal surfaces, since there is a gap in
the mesial lobe between the small right and large inter-
mediate portions where it is lodged — the gap being nearly
1 cm. wide. It is a somewhat elongated body, and rarely
is found projecting beyond the ventral edge of the
liver, though in Pseudochirus I have seen it projecting
1.5 cm. beyond. It measures about 2.5 cm in length,
though in an adult male specimen I found the bladder
was only 1 cm. long, and lay in the dorsal part of the cleft.

112

Biliary and Portal Systems. Liver. Australian Phalanger.

H Stomach. P Pancreatic Duct, D Duodenum, N Duod.-Intest.
Flexure. S Spigelian Lobe, C Caudate Lobe, R Right Lateral
Lobe. L Left Lateral Lobe, RM Right Mesial Lobe. IM Inter-
mediate Mesial Lobe, LM Left Mesial Lobe.

113

AUSTRALIAN PHALANGITES.

It is for the most part a mobile organ, being freely in-
vested with peritoneum, in contrast with the limited in-
vestment of the human liver, in which the peritoneum,
apart from the fundus, invests the under surface and
sides only. Its dorsal extremity is invested on the sides
and ventral surfaces only, being attached above to the
hepatic substance. In Pseudochirus lateral bands are
noted connecting this dorsal portion with the liver,

Cystic Duct. — This lies in a groove between the small
right portion of the cystic lobe and the projection on the
right side of the intermediate portion — the result of an
accommodation effect for the gall bladder. It measures
1.25 em. long, but in Pseudochirus is rarely longer than
1 cm. At the portal interval or fissure it is joined by the
hepatic ducts and becomes the common duct.

Hepatic Ducts. — On the left side a single trunk is
noted, formed by the junction of two main divisions, the
smaller for the left and intermediate cystic or mesial
lobes, and the larger from the left lateral lobe. On the
right side a small branch from the right cystic joins the
larger branch from the right lateral, close to the junction
of the latter with the cystic duct.

The Common Bile Duct. --This passes down between
the spigelian and caudate lobes, with the hepatic artery
and portal vein (the vein being placed dorsally) lying at
first in the right extremity of the lesser omentum, and
forming part of the ventral boundary of the Foramen of
Winslow. This foramen serves to define the right ex-
tremity of the lesser omentum from the meso-duodenum,
since the duodenum itself is not fixed. The duct ter-
minates in the duodenum about 5 cm. from the pyloric
opening, and measures 4.5 to 6 cm. in length. The pan-
creatic duct, which is traced in the pancreatic tissue as far
ji 114

AUSTRALIAN PHALAXGEES.

to the left as the spleen, opens into the common bile duct
1.5 to 2 cm. before it terminates in the duodenum. On
opening the duodenum the termination of the duet is
defined by a slight papillary projection. After the en-
trance of the pancreatic duct the combined hepatic-pan-
creatic duct gradually widens, and for the last 1 cm. the
circumference is double that of the common bile duct.
In Pseudochirus the combined duct lies ventral to the
upper pole of the right kidney, to which the meso-duo-
denum has become attached.

Portal Vein. — On the right side a branch is seen pass-
ing to the right lateral and caudate lobes. Passing ven-
trally a well defined branch is seen passing on the left to
the left lateral lobes, and on right to right mesial. It
finally terminates in two branches, which are traced to
the left mesial and intermediate mesial lobes.

Lesser Omentum. — The upper or hepatic attachment
is short, and is traced from the inf. vena cava exit, dor-
sally, where it is continuous with the suspensory liga-
ment. It is traced to the ventral surface at the concavity
for the oesophagus on the dorso-internal part of the left
lateral lobe, and lies along the dorso-int. part of the left
lateral lobe, between it and the lobus spigelii, up to the
portal fissure. A peritoneal band ventral to the lesser
omentum is traced from the under surface of the left
hepatic lobe to the lesser curvature, corresponding to a
bend in the stomach between right small pyloric and left
large cardiac portions.

Pancreas in Trichosurus. — As in the Platypus, the
pancreas may be characterised by its diffuse char-
acter. It does not fill the duodenal loop but occupies
the portion of the meso-duodenum above the attach-
ment of the colon, being chiefly found in the

115

«f>To/~\ACH

rtE5o-DUO"DENUfA
P>OOT OF

COLON
DOoT>-»rAT£t>T

Duodenal

LOOP

Fi*E"D COLON
D\JOT>. Fot>t>ft

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duodenum

lieno-mesocol/c rou>

WITH

RENAL. ATTACHMENT.

M£S£N TGRY

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MESOCOLON

MESENTERY

The Gastro-Intestinal Tract, Spleen, and Portion of Pancreas.

Trichosurus.

116

AUSTRALIAN PHALANGERS.

limited interval about 1.5 cm. between the colon
and the first part of duodenum, extending as far
to the left as the right limitation of great omentum. On
one occasion I traced some strands of pancreatic tissue
in lesser omentum up to the portal interval. Just above
the duod-intest. junction, where it is fixed dorsally, the
pancreas is seen passing to the left towards the spleen as a
compact piece coming into relation with the lesser sac
(great omentum), the lower dorsal boundary of which it
forms, and strands of pancreatic tissue may even be sent
on to the lesser sac. The pancreas is finally found to be
outside the lesser sac in relation with the small left process
of the spleen and the lieno-mesocolic fold connecting left
process of spleen, kidney, and mesocolon ; not being found
in relation with the body or right anterior process. At its
termination on the left at the spleen, in those cases where
its character was diffuse on the right, it becomes more
compact. The greatest length of the pancreas in the
phalanger is about 6 cm.

Pancreas in Pseudochirus. — In Pseudochirus the
pancreatic tissue is relatively greater in amount than in
Trichosurus. A well defined piece is found about the duct
entrance (to the left of which a small process is seen), and
this is continued down to the duodenal loop closely
attached to the duodenum, strands even extending to the
extremity of the loop. These are all in the meso-duo-
denum. The pancreas passes thence from the meso-duo-
denimi to the left by processes running in two directions,
which are best seen by throwing up the colon on to the
liver. One of these — the larger— is anterior or ventral,
and lies between the colon and stomach, being within the
lesser sac, and is traced outwards on the left in relation
with the anterior right process and body of the spleen,
and comes in relation with the "gastro-splenic" omentum.

117

G£6oPHft6US

PYLORIC SPHlNCTfR

BiLE DUCT

PANCRtftTlc/

DUCT

r>u

RloH

ILEAL

JUNCTION

srEaT Cm NTun

(L£ = 3EK Sac)

DiSTAL COLON
INCLUDE-D i^»
LEi>iE_R. i>ftC

LON&ITUDINPil

rluscLE

The Gastro-Intestinal Tract. Pseudochirus.

118

AUSTRALIAN PHALANGERS.

The other lower, or dorsal, portion is a much finer strand,
and is traced above the root of the mesentery, being in
relation with the dorsal wall. The pancreas is greatly
increased in amount on the left, and is prolonged outside
the lesser sac in relation to the inner surface of the lesser
process of the spleen, being traceable across the kidney
to its outer side. This portion is on the lieno-mesocolic
ligament, which has receded compared with Trichosurus,
and brings into relationship the mesocolon, omental sac,
spleen, pancreas and kidney. The point is that the greater
part of the pancreas in Pseudochirus is within the lesser
sac.

119

LIVER OF AMERICAN OPOSSUM

(DIDELPHIS MARSUPIALIS.)

Here important differences as regards the mesial
lobe are noted when compared with Trichosurus.

On the Diaphragmatic aspect we notice three pri-
mary divisions of the liver, viz., mesial, small right, and
large left lobes. These are separated by well defined
complete fissures, viz.. right and left lateral fissures,
(page 100. ) The mesial or cystic lobe is usually the largest
of the three, and the ventral cleft or fissure, about 1.5 cm.
long, for the gall bladder, forms on this aspect its separa-
tion into right and left mesial or cystic lobes. On the
dorsal aspect of the mesial lobe, to the left of the gall
bladder fissure or cleft, is the suspensory ligament, which
does not come forward to the ventral edge. On this edge,
however, to the left of the gall bladder cleft, a small fis-
sure, about .5 cm. long, may be met with. Prolonged dor-
sally this would reach the suspensory ligament, but there
is no depression between the two. I have, however, seen
a distinct line, almost a depression (faint), from the liga-
ment to the ventral edge, which latter, however, was not
fissured. Here we see an early indication of the forma-
tion of the cystic or mesial fissure leading to the tripartite
cystic lobe. It is not an instance where fusion of the inter-
mediate and left cystic lobes has taken place, for in those
instances the suspensory ligt. has corresponded to the
gall bladder fissure, while here it is distinctly to the left.

120

AMER IC AN ( )P( )SSUM.

Visceral Surface. — The left lateral lobe extends ven-
tral to the left cystic lobe, occluding it, and may extend to
the right of the gall bladder. It is concave for the body
of the stomach. The cleft for the gall bladder and the
well defined fissure passing dorsally for the cystic duct
divide the mesial or cystic lobe into right and left por-
tions. The right cystic is related to the pyloric portion
of the stomach. ( Page 102. ) The right lateral lobe is the
smallest of the three, and on its ventral aspect is a well
defined and separate caudate lobe, hollowed below for the
kidney. This is prolonged to the left as a small spigelian
lobe. Between the two passes the portal vein, artery, and
duct, and at the dorso-internal portion of the caudate is
the hepatic entrance of the inf. v. cava.

12.1

OBSERVATIONS.

Diffuse or Compact Liver.

If we take the Platypus at one end of the Mammalian
scale, and Man at the other, a striking feature of the liver
is the multiplicity of lobes (divisibility of hepatic tissue)
in the former, and the compactness or tendency to uni-
fication in that of the latter. This we find true, not only
as regards the liver, but also the spleen and pancreas.
For the erect attitude consolidation would be advan-
tageous for fixation, and so, amongst other things, the
tendency to torsion lessened.

Development of the Mammalian Liver.

The hypoplastic diverticulum, or liver bud, springs
from that portion of the fore gut which will afterwards
become the second portion of the duodenum. Portion of
this gives rise to the liver tissue, which at first consists of
right and left masses of cells, and portion gives rise to
the gall bladder and main ducts. It is interesting to note
that all the specimens examined conform generally to a
simple plan, namely, right and left lateral portions or
masses, with the portal vein, and gall bladder, cystic, and
common ducts, as a common stem. On the right side
hepatic and portal branches are traced to the right por-
tion (right cystic and right lateral), and on the left side
branches pass to the left portion (left cystic and left

122

OBSERVATIONS.

lateral). This supports the contention of James Cantlie,
[Who, in his important paper, held that a line drawn
through the human gall bladder to the vena cava, at the
dorsal border, divided the liver into right and left parts.
This is well shown by a reference to the diagram of the
liver of Dasyurus Viverrinus, which represents the most
primitive Mammalian liver I have met.

Fixation of the Liver.

In Man the liver is separated dorsally with great dif-
ficulty. It is firmly held — apart from the suspensory
ligament — by close adhesions to the diaphragm. In the
Monotremes and Marsupials, however, the liver, as shown
in the diagrams of the diaphragmatic surface, is less
closely held dorsally. It can be easily separated. Firm
dorsal fixation of the human liver is an adaptation to the
erect position. This is associated, as in the case of the
spleen and pancreas, with compactness, and so displace-
ment and tendency to torsion is avoided. There is a
greater fixation of the liver of the Koala than in the other
Marsupials. This I regard as associated with the great
weight of the proximal colon and caecum (length of the
latter sometimes reaching 240 cm.), which are swung on
the common mesentery. The colon is suspended to the
pyloric region by a strong mesial fold, and so torsion is
prevented. As traction is transmitted to the liver through
the lesser omentum the advantages of a firm hepatic at-
tachment is obvious. Furthermore, when feeding, this
animal sits erect.

Bile on (I Pancreatic Ducts.

In both orders no separate entrance of the pancreatic
duct into the duodenum — apart from that associated with
the bile duct — is noted, i.e., the duct of Wirsung is the

123

OBSERVATIONS.

vehicle for the conveyance of pancreatic secretion. In the
carnivorous Marsupial, as well as the Opossum and the
herbivorous Kangaroo, the pancreatic duct opens into
the common bile duct, as in the more primitive Mono-
tremes, whilst in the Koala and Wombat the condition — ■
with an independent control — resembles Man more
closely. In the Koala a diverticulum is noted at the ter-
mination of the pancreatic duct. This animal is ex-
clusively an Eucalyptus-leaf eater. By means of the
reservoir, or diverticulum, a more perfect control of the
pancreatic secretion necessary for digestion is instituted.
In the Wombat and Kangaroo the entrance of the bile
duct is nearer to the duod-intest. flexure than to the
pyloric sphincter, whilst the reverse is noted in the Mono-
tremes and other Marsupials. The reason is not easy of
explanation. The duod-intest. flexure is to be regarded
as a constant. In all the animals described it corresponds
to the entrance of a direct branch of the right vagus. If
we regard the liver as an outgrowth of the duodenum, i.e.,
of that portion of the gut whose dorsal mesentery (meso-
duodenum) represents comparatively a failure to de-
velop, then the site of the entrance of the duct will depend
on function. In the Wombat, e.g., the lining membrane
of the duodenum, down to the entrance of the duct, is
rugous and scarcely distinguishable from that of the
stomach. In this animal pancreatic and hepatic secre-
tions are not necessary till the food has almost traversed
the duodenum, i.e., almost immediately before the release
at the duod-intest. flexure of the food into the small gut,
m marked contrast to Koala and the Monotremes. As the
entrance of the vagus nerve at the duod-intest. flexure is
to be regarded as a constant, and the entrance of the duct
as a variable, it points to the importance in control of
the former.

124

OBSERVATIONS.

Multiple Bight-Sided Lobulation in Sarcophilus

and Koala.

In these two highly specialized feeders — the one car-
nivorous, and the other phyllophagous — extensive right-
sided Assuring and lobulation is noted. The effect of
this must be to improve the elasticity of the organ. In
the Koala we have, as stated, a large proximal colon and
caecum dependent from the pyloric region by the mesial
band, and this would be advantageous. Possibly also this
is a factor in preventing rupture of the organ from in-
juries during climbing. On the other hand these causes
are not operative in the Tasmanian Devil, and further-
more, its intestinal tract is primitive. It is noteworthy,
however, that the lobulation and Assuring are most
marked in the varieties of liver where the right cystic
and right lateral lobes tend to become fused.

The Spigelian and Caudate Lobes.

In the Monotremes and the Tasmanian Devil the
caudate lobe is well developed, while in the Kangaroo and
Wombat it may be regarded as non-existent. In the
Monotremes and those Marsupials with a defined caudate
lobe (to which may be added the Gorilla amongst pri-
mates) the inf. vena cava is not seen on the visceral sur-
face. It lies dorsally behind the junction of the caudate
and spigelian lobes. In the Kangaroo, Wombat, and Man
the vena cava is seen on the visceral surface in its hepatic
relationship. In an Orang, three months old, in the
Hunterian Museum, there is a well defined caudate lobe.
The inf. vena cava, which measures 2.5 cm. in its hepatic
relationship behind the caudate and spigelian lobes, is
not visible viscerally, and only on diaphragmatic surface
for its terminal, .5 cm. In connection with the inf. vena

125

OBSERVATIONS.

cava and the caudate lobe of the early human foetus the
additional placental circulation must be borne in mind.
Furthermore, in the more primitive livers, the caudate
lobe is to a large extent an accommodation effect for the
upper pole of the right kidney, as is seen in the Echidna.
With, however, the comparative fixation of the duodenum
and pancreas, and unification of the organ, a more limited
relation of the kidney to the liver is seen.

The spigelian lobe is well defined in the Monotremes,
but reaches its maximum in the Macropodida?. It is poorly
developed in the remaining Marsupials, and in the Wom-
bat it may be regarded as non-existent. In the Platypus
its definition is associated with four factors: —

(a) Ventral to it lies the lesser omentum.

(b) On the left side, looping round it, are the

oesophagus — pcyloric knob — and commence-
ment of duodenum.

relationship, which is dorsal.

(d) On its right we see the portal vein, artery, and

duet, in a well defined depression between it
and the caudate lobe.

In Macropus we have the large spigelian lobe dipping
down within the lesser sac in the interval between the
right and left portions of its great stomach. In relation
with this is a large abdominal oesophagus, frequently
reaching 10 to 12 cm. in length. Defining it on the right
we see the inf. v. cava, ventral to which lies the portal
vein, artery, and bile duet. In neither Koala nor Wom-
bat is there an abdominal oesophagus. According to the
late Professor Cunningham, an abdominal oesophagus of
varying length can usually be described in the human sub-

126

OBSERVATIONS.

ject. The association of a well defined abdominal oeso-
phagus with any increase in size of the spigelian lobe is
worthy of note. In the human liver, in addition, the
ventral position of the inf. v. cava and the ductus venosus
are factors helping to retain a spigelian projection.

U union Liver and Its Abnormalities.

Occasionally, human livers are met with presenting
curious fissurings and lobulations, which are classified as
abnormalities, but the significance of which is explained
by a study of Australian mammals. In what may be re-
garded as a typical mammalian liver a primary division
into five lobes may be recognized, namely, the mesial or
cystic, lodging the gall bladder, which is separated on
either side from the right lateral lobe and left lateral lobe
by the right and left lateral fissures, and on the visceral
surface of the right lateral lobe, as is well shown in
Platypus, we have projecting the lobus spigelii and
dextrally the larger free caudate lobe. The spigelian
lobe reaches its maximum development in the Kangaroo,
where it dips down within the lesser sac in the interval
between the right and left portions of the great stomach,
being grooved for the passage of a large abdominal oeso-
phagus, 10 to 12 cm. in length. The caudate lobe, on the
other hand, though well defined in Platypus, and
especially in Echidna, may be regarded as non-existent in
Kangaroo and Wombat. In the Echidna it is seen to be
largely an accommodation effect for the upper pole of the
right kidney and adrenal. With comparative fixation
of duodenum and pancreas and unification of the organ,
a more limited relation of kidney to liver is seen, with
disappearance of the right lateral fissure. Amongst the
members of the Australian fauna, the gall bladder forms
a separation of the mesial or cystic lobe into two primary

127

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P^1-1U

OBSERVATIONS.

divisions, the right and left cystic Lobes; and in the Wom-
bat, Koala, Phalanger, and Bandicoot, a definite separa-
tion of the left division into two portions by means of a
fissure, the mesial or cystic fissure has taken place, so
that three portions of the mesial lobe are recognized, viz.,
right mesial, intermediate mesial, and left mesial. The
suspensory ligament is noted in relation with the mesial
fissure, between the intermediate and the left mesial
lobes, and not with the left lateral fissure, between the left
mesial and the left lateral lobes. The conveyance of
maternal blood to the liver, along the suspensory liga-
ment, would be a factor favouring the retention of the
mesial fissure, as compared with the left lateral fissure.
The human longitudinal fissure corresponds to the mesial
or cystic fissure, as is well shown in a study of Gorilla
and Wombat, and the intermediate mesial lobe, i.e.,
between the gall bladder and the mesial fissure, is
represented in the human liver by the lobus qnadratus.
In the Wombat, in which animal great diversity of liver
shape is met with, from the primitive multilobed type to
one scarcely distinguishable from the human, irregulari-
ties can be studied in connection with this lobe, giving us
an indication of its instability. It would further
appear that cases of atrophy of the human lobus
qnadratus often met with represent the trend of Nature's
evolution towards further unification and simplification
of the organ, a fact to be remembered in cases of so-called
"displacements of the gall bladder.'' This is the experi-
mental region of the liver, and there is no reason why
the gall bladder fissure in the human liver should not
serve for the convevance of the maternal blood to the
portal fissure and vena cava, especially when we consider
the proximity of portal vein and bile duct to the inferior
vena cava in Kangaroo. In William Flower's classifica-
tion of the lobes of the liver, followed generally by bio-

129 k

OBSERVATIONS.

logists, the longitudinal fissure is taken as the line of
separation of the right from the left side. The left
human lobe, however, really consists of the original left
lateral lobe, together with the left mesial lobe, the original
left lateral fissure having disappeared. The ideal divi-
sion would be one applicable to all the mammalia, and
Flower's arrangement is not even applicable to all mem-
bers of such closely-allied orders as Monotremes and Mar-
supials. It could not apply to the Monotremes, Kangaroo,
Tasmanian Devil, and some varieties of Wombat, nor
would it hold for the liver of the Gorilla, in which the
mesial or cystic fissure (human, longitudinal) is dimi-
nutive compared with the left lateral fissure. The divi-
sion is best dominated bv the arrangement of the vascular
and biliary systems. In a minute examination of livers
belonging to Monotremes and Marsupials, I found that
they conformed to a single plan, viz., right and left por-
tions, with the portal vein, gall bladder, cystic and com-
mon duets, as the common stem. On the right side
of the stem, cystic and venous branches were trace-
able to the right lateral and right mesial lobes, and
on the left side to the left lateral and intermediate mesial
and left mesial lobes. The true line for the division of
the liver into right and left portions would be from the
fundus of the gall bladder through the portal fissure to
the dorsal border, as originally defined bv James Oantlie.
Apart from comparative anatomy, this division is sup-
ported by pathological findings. We can inject sepa-
rately into one or other side of the human liver. New-
lands, the distinguished Adelaide surgeon, has told me
that he has seen hydatid involvement of the right side
of the liver, with compensating enlargement of the left,
and Oantlie observed this in connection with atrophy of
the right side following chronic abscess, in which the liver
was almost of normal weight. This conception of the
kl 130

OBSERVATIONS.

liver offers up a new and interesting field in connection
with the distribution and treatment of cancer, hydatid,
and sepsis.

From a study of comparative anatomy, we see
how the human liver and spleen acquire their shape. The
question naturally arises : if the liver cells perform mul-
tiple functions, are the functional activities different in
different portions of the organ? This would be best
studied in the more primitive multilobed livers, like those
of the Marsupials and Monotremes. And, similarly, in
connection with the spleen, for it must be remembered that
human spleens are often met with in which the body and
right and left processes are all separately defined. To
know the sequence of acquisition of function of liver cells
is essential to a proper classification of diseases of the
organ, for loss of one or more, not necessarily all, the
functions of a cell must be surely as characteristic of
hepatic disease as it is in connection with loss of function
of a muscle.

Determining shape we must remember the following
factors : —

(1) Adaptation to surrounding structures.

(2) Influence of respiration.

(3) The orthograde posture.

(-t) Relation of the heart to the diaphragm.

The left hepatic lobe is well developed in the Mono-
tremes and Marsupials, but the heart is not related to
the diaphragm as in the case of Man and the Anthropoids,
since, with the exception of the Koala, the azygos lobe
from the right lung intervenes. Attention has frequently
been directed to the primitive type of the liver of the
Gorilla — the most orthograde of the Anthropoids. More
interesting, however, is the fact that members of the

131

OBSERVATIONS.

Phaseolomyidae (Marsupials and Pronogrades) should
exhibit a liver in some instances primitive in character — •
in some almost indistinguishable from the human — and
in some intermediate, in type, between the two. As I
have already pointed out, the internal arrangement of
the Wombat's abdomen approximates closely to the
human, and this is especially noteworthy as regards the
spleen, pancreas, and the vermiform appendage, as well
as the liver.

132

THE SPLEEN AND PERITONEAL

RELATIONS IN MONOTREMES

AND MARSUPIALS.

THE SPLEEN IN MONOTREMES.

Platypus (Ornithorhynchus anatinus.)

On opening" the abdomen of the Platypus, concomit-
ant with the presence of a diaphragm and great omentum
one is struck by the large development of the spleen and
pancreatic tissue, and the right stem of the former may
extend from the left hypochondrium to the right iliac
region.

The spleen (p. 136) is somewhat V-shaped, and three
portions are recognised, viz., a small body 2.5 to 3 cm.
long directed towards the oesophagus and in the great
omentum (lesser sac) ; a large right ventral (anterior)
process lying freely in the abdominal cavity and sus-
pended also in the great omentum, 12 to 15.5 cm. long,
with the width varying from 2 to 2.5 cm. and thickness 1.5
cm. ; and a shorter left dorsal (posterior) process 7 to 9
cm. long, with a width of 1.75 to 2 cm. and thickness of
nearly 1 cm. This left process is outside the lesser sac in
relation with a fold — the left lateral or lieno-mesocolic-
connecting it to the mesocolon of the left or distal colon.
The distal colon is never fixed dorsally, and the average
maximum width of the mesocolon equals 5 cm. The pan-
creas is found diffusing itself on the left aspect of the
mesocolon in relation with the left lateral fold. The fold
with the left splenic process and pancreas can be lifted
free from the ventrum of the left kidney and the dorsal
wall. Whilst the right process and body of the spleen are
continuous, the left process is arched and forms practi-
cally a right angle with the body. A deep notch is present

135

CE SO"1AOuS

SVT»-(/vCe Of OUCT

5 tOma C*i

SPl.EE* (Boor)

*«& GT OMENTUM

- cesser- Sac

DUODENAL LOOP

Lr Post pboc

MtSO OuOOEnuni

PRO* 1MA1. COLON
Stvung on meienter?

LiL,NO MESOCOLlC FOlO

atc pal j

Distal. Colon
(3~unp- on mesocolon)
n3t in own /

RT ANT PROC

Gr Omentum
Lesser Sac

The Peritoneal Relations of the Spleen in Platypus.

OESOPHAGUS

STOMACH
PYLORUS
DUO DEN UNI

ff ANT PROC

GT Omentum

LESSER SAC

«5da TOWARDS

OESOPHAGUS

Spleen

L T POST. PROC-

LT LAT. FOLD
LiENO "ESOCOLIC

MESOCOLON

The Peritoneal Relations of the Spleen in Echidna.

136

TPiE SPLEEN IN MONOTREMES.

at the cephalic margin between the two, and the actual
width of attachment may be less than 2 cm. One or two
small notches may be noted at the caudal border near the
termination of the lesser process, and a notch directed
towards the body between the right and left process. It
is interesting to note that in an Agama (Reptilia) measur-
ing 30 cm. snout to vent and abdominal width of 7 cm. the
spleen was 1.5 cm. long and .4 cm. wide, while the snout to
vent measurement of the Platypus is 37 cm. and width
13 cm.

Echidna (Echidna aculeata),

As in the Platypus, three main portions of the spleen
may be recognised (p. 136), viz., body and two processes;
but while uniformity is characteristic of the spleen of the
Platypus, although conforming to the general character
it is rare in the Echidna to find two spleens alike.

(1) Body. — This is better defined than in Platypus
and is in relation to the stomach fundus, being directed
towards the oesophagus. It is suspended in the great
omentum, the width of which, even in a male adult, only
equals 1 cm. ; and so at this early stage we obtain the
definition of a gastro-splenic omentum. Its length varies
from 3 to 5 cm. and the width .5 to 1 cm.

(2) The right ventral process is the longer of the
two and is also suspended in the great omentum (lesser
sac), the width of which at its anterior extremity is 7
cm. ; so that it is more mobile than the body. Its average
length is 5 to 7 cm. and width .5 to 1.5 cm.

i^'

(3) Left Dorsal Process. — This is shorter than the
anterior, and two portions may be recognised, viz., a stem
terminating in a pear-shaped body, which may be smooth
or (especially in smaller specimens) corrugated. The

187

THE SPLEEX IN MONOTREMES.

stem rarely runs directly into this portion. Usually there
is narrowing at the point of attachment, and the connec-
tion between the two may be merely a slender fibrous
thread. The stem varies from 1.5 to 3 cm. in length and
average width .5 cm., while the body varies from 2 to 3.5
cm. in length and circumference may reach 5 to 6 cm.
This process, as in Platypus, lies outside the lesser sac
in relation to the lieno-mesocolic fold, extending caudally
towards the pelvis on the left of the distal colon. In one
specimen out of a large number examined, I found the
left stem included in the lesser sac. The distance between
the pear-shaped body and colon may only equal .75 cm.
The pancreas is a less mobile organ than that of the
Platypus, and in not one of the numerous specimens
examined by me did it extend sinistral to the lesser sac,
so as to come into relation with the lieno-mesocolic fold.
The distal left colon is mobile, having a mesocolon. In
one specimen this was greatly narrowed and the length of
the distal colon in the abdomen only equalled 7 cm. In
another — a male specimen — the pancreas was a " fixed' '
organ and on the right side was adherent to the lobus
caudatus. The left or distal colon was fixed dorsally,
describing an almost vertical course to the pelvis. In
close relation in this specimen, and all fixed dorsally in the
left lumbar region, were the left testis, kidney, pear-
shaped process of spleen, and distal colon. The pancreas
extended but a short distance on the left of the colon and
apparently had little influence in the fixation of this struc-
ture, since it never extended to the left in relation with the
lieno-mesocolic fold. Yet fixation has occurred. In this
specimen, as well as the one with a shortened mesocolon,
the distal left colon was relatively short; there was a
failure to develop, with atrophy of the mesocolon. In-
stead of the distal colon from the duodeno-intestinal
flexure to vestibule being 28 cm. long — the average adult
male length — it only measured 13 cm.

188

THE SPLEEN IN MARSUPIALS.

In this order we meet not only with types of spleen
presenting the early mammalian character seen in the
Monotremes, but with types becoming dorsally fixed and
resembling closely the human spleen.

Tasmanian Devil (Dasyurus sarcophilus).

In this Marsupial there is a well-defined great
omentum extending from the pyloric region to the left
along the great curve of the stomach. No duodenal loop
is present, and no well marked distinction between colon
and small intestine as in other Marsupials. The intestinal
tract is reptilian in character, consisting of a canal 157
cm. from pylorus to pelvis, swung apparently on a single
mesentery 7 cm. long at its dorsal attachment. This latter
consists of two portions — an upper 1.5 cm. long (superior
mesenteric) and corresponding to the duodenum and
small gut (135 cm.), and a lower (5 cm.) representing the
original mesocolon and corresponding to the remaining
22 cm. of intestine, which is large gut. (Page 94.)

As in Macropus, the spleen presents three distinct
portions : —

(1) A large portion or body directed along the great
curvature of the stomach towards the oesophagus. It is
swung on the great omentum, which is 2 cm. wide at the
left extremity and 10 cm. at the right. At the left
extremity, in addition to the shortened omentum (gastro-

«. 7

139

THE SPLEEN IN MARSUPIALS.

splenic), a peritoneal band stretches across the omentum
between the stomach and spleen. The body varies from
7 to 8 cm. in length, and greatest width is 1.75 cm.

(2) The right ventral process is also in relation with
the lesser sac, being swung freely on the great omentum.
It varies from 4 to 5 cm. long and is about 1.75 cm. wide.
This portion forms almost a right angle with the body.

(3) The left dorsal process, 2.5 cm. long and 2 cm.
wide, is outside the lesser sac and gives attachment to the
left lateral fold. This membrane is somewhat triangular
in shape and measures 9 to 10 cm. long, and over it the
main pancreatic tissue diffuses itself, but it never extends
nearer than 2 cm. to the dorsal attachment. The basal
portion of the membrane (5 to 6 cm. long) extends from
the root of the mesentery out along the lower part of
the lesser sac to the left dorsal process of the spleen. Its
left margin is free. The right margin is not continuous
dorsally with the mesocolon of the large intestine, but
with the peritoneum slightly to its left. The left lateral
fold, as in the Platypus and Kangaroo, is free from dorsal
wall and ventrum of the left kidnev.

Koala (Phascolarctus cinereus).

The spleen is suspended in the great omentum, being
contained in the lesser sac, and is characterised by the
relative shortness of the left dorsal process and the
absence (this being the only instance among Marsupials
and Monotr ernes) of the left lateral or lieno-mesocolic
fold. The shape of the spleen varies slightly in different
animals. In all there is an elongated right ventral pro-
cess varying from 7 cm. to 12.5 cm. long. It is usually
constricted and fissured where it joins the main splenic
mass. The remainder of the spleen or body may approach

140

THE SPLEEN IN MARSUPIALS.

somewhat in shape the human type, forming a triangular
body 7 cm. long and 4 cm. across, with two small projec-
tions, one directed towards the oesophagus and the other
representing the left dorsal process. The right process
is much more mobile than the body, and while the width
of great omentum between the left extremity and great
curve of stomach equals 2.5 cm., at the right extremity
this equals 9 to 10 cm. In some specimens the body is not
relatively so large, and in place of the projections two
processes are seen, separated by a well-defined interval or
gap.

M aero pod id ae (Kangaroos and Wallabies,)

The spleen consists of three portions : (1) left, largest
portion or body; (2) narrow elongate or right process;
(3) wider, though shorter, dorsal left process.

The body varies from 11 to 15 cm. in length, with
a maximum width of 4.5 cm. The short left process is 6
cm., with a maximum width of 3 cm. ; and the right pro-
cess 9.5 cm. long, and maximum width 3.75 cm.

Frequently the width of this process may only equal
1 em., with a narrow attachment to the body — the connec-

7 *s

tion being fibrous, with a sprinkling of splenic tissue.
Such a process is one apparently undergoing a retrogres-
sive evolution, and is found both in the Wallaby and
Kangaroo. In the Tasmanian Wallaby I found the
anterior process to be not only narrower but shorter than
the left process. The great stomach in Macropus is a
V-shaped organ with a large left and a smaller right
limb, and the well-defined Spigelian lobe of the liver de-
pending between the two. The body and elongated right
process are suspended on the great omentum (lesser sac),
being related to the greater curvature of the left limb
as far to the right as the bend in the stomach. The pro-

141

o
o
a:
a

142

THE SPLEEN IX MARSUPIALS.

cess is less closely attached than the body. The short,
wide left dorsal process is outside the lesser sac, being con-
nected to the mesocolon of the distal colon by the triangu-
lar fold, the left lateral or lieno-mesocolic, which is more
developed in some specimens than in others. It is free
from the dorsal wall and ventrum of the left kidney. Both
as regards its shape and the disposition of the left lateral
fold, the spleen of the Macropod presents the primitive
Mammalian type, and resembles closely that of the Mono-
treme.

True Phalangers (Trichosurus — Pseudochirus) ,

In Trichosurus a marked advance towards the
human type of spleen is to be noted, and light is thrown on
the formation of the lieno-renal ligament and the mode
of fixation of the distal colon and spleen. Although three
portions of the spleen are noted, viz., body, right, and
short left processes, the organ is more compact and the
processes less defined than in the preceding mammals
(page 116). The body is directed towards the oesophagus
and is suspended — like the right ventral process, which is
directed along the great curvature of the stomach — on the
great omentum, i.e., lesser sac.

The width of the great omentum (gastro-splenic) at
the extremity of the body is 1.5 cm., and at the extremity
of the right process the width is 5.5 cm., so that the nar-
rowing gastro-splenic omentum is here well defined. The
short left dorsal process is outside the lesser sac in rela-
tion with the left lateral fold. Its average length is only
1.5 to 2 cm. The total average length of the spleen is
7 cm. and the width 1.5 to 2 cm. In addition to the outer
or left and inner visceral or right surfaces, three margins
can be defined, viz., renal or dorsal margin formed by
the body and left process; right ventral margin formed
by the body and right process; and left colic margin

143

THE SPLEEN IN MARSUPIALS.

formed by the left dorsal and right anterior processes.
On examining the inner or visceral surface (page 154) of
the spleen we are struck with the resemblance borne to
that of Man and the Wombat. We note a well-defined
renal surface, concave, formed bv the body and left
process; a gastric surface formed by the body and right
process, with the gastro-splenic omentum (great omen-
tum) attached along a groove extending from the ex-
tremity of the body to the extremity of the anterior pro-
cess. This surface is separated dorsally by a distinct
raised edge from the renal surface, but unless there is a
defined concavity this is not marked. From the gastro-
splenic omentun, running down the left dorsal process,
we see the attachment of the left lateral fold (lieno-
mesocolic). This, with the anterior part of the gastro-
splenic omentum, separates off the lower left or colic
surface. Below the attachment of these two membranes
we have a ridge simply the result of the impressions of the
colon and stomach, just as the posterior ridge separating
the renal from the gastric surface is the result of the renal
impression. The lieno-mesocolic (left lateral fold),
instead of being free as in the preceding specimens from
the short left splenic process to the mesocolon of the distal
colon, has, in addition, become attached to the ventrum
and outer surface of the lower half of the left kidney.
The result is that the spleen and left portion of the
pancreas which is supported on the fold are brought into
relation with the kidney, and so we have defined the
concave renal surface of the spleen related to the upper
and outer convex portion of the kidney — the pancreas
lying ventral to that organ. Thus we see that we have a
definitely formed lieno-renal fold which is really the
upper part of the lieno-mesocolic fold, and the lower part
of the fold is really now reno-mesocolic. A peritoneal
hand is noted in both Trichosurus and Pseudochirus from

144

THE SPLEEN IN MARSUPIALS.

the middle of the convex border of the kidney to the
Lateral abdominal wall, and continuous over the kidney
with the lieno-mesocolic fold. The attachment of the
lieno-mesocolic fold to the left kidney (zygosis) is thus a
factor in bringing the spleen into close relation with
that organ, and this is more marked in some specimens
than in others. In two specimens the pancreas lay
ventral to the left kidney, and the renal surface of the
spleen was related to the outer part ; but all could be
raised off the kidney, as they were suspended on the
lieno-mesocolic fold, and this was not attached to the
ventrum of the kidney as above described. The fold,
however, was really lieno-renal, as its lower attachment
was to the dorsal wall at the lower pole of the kidney, i.e.,
it did not extend to the mesocolon, the lower portion
being atrophied. In a smaller variety of Australian
Phalanger (Pseudochirus), though the spleen is prac-
tically similar to that of Trichosurus, the fixation of
structures in the left hypochondrium and lumbar regions
is more pronounced. The renal surface of the spleen is
in relation with the upper and outer convex surface of
the kidney, and the left process of the spleen can be raised
slightly oif that organ. The pancreas, however, is seen
to be in close relationship with the ventral and outer sur-
face of the kidney. In Trichosurus the left distal colon
and meso-colon are free of lesser sac, but in Pseudochirus
they are included for about 8 cm. This inclusion must be
an important factor in approximating colon to spleen,
although in Pseudochirus it is associated with a large
process of pancreatic tissue in the lesser sac and free
from the dorsum. Whilst in Trichosurus the colon and
mesocolon are not brought close to the kidney, in Pseudo-
chirus the lieno-mesocolic fold is relatively shortened up
and the mesocolon is brought in direct relation with the
caudal pole of the kidney, so that we find in close connec-

145 l

THE SPLEEN IX MAESUPIALS.

tion pancreas, left process of spleen, kidney, and meso-
colon, only the shortened remains of the lieno-mesocolic
fold intervening. In these two varieties of Phalanger
important light is thrown on the combination of corre-
lated factors necessary to produce the close relationship
of spleen, pancreas, and colon in the left human hypo-
chondrium.

Wombat (Phascolomys) ,

The spleen is placed in the left hypochondrimn in rela-
tion with the left part of the stomach and upper portion
of the left kidney. It may be described as triangular in
shape, presenting three margins: (1) dorsal or renal;
(2) right, gastric, or ventral: (3) left, lower, or colic.

We also note three extremities or angles, viz., an
oesophageal or upper, a right ventral, and a left ex-
tremity. In addition, two main surfaces, viz., outer,
lateral or left, and inner, mesial, visceral, or right. its
greatest length is 12 cm. and breadth 11 cm.

Extremities. — (a) The oesophageal or superior ex-
tremity is most dorsal and frequently the most pointed,
and lies 3 to 4 cm. from the sesophagus. It is in relation
with the great curvature of the stomach, to which it is
connected by gastro-splenic omentum, i.e. upper part of
the great omentum, and which is thickened in this region,
with a width of only 1 cm. Frequently, as in the human,
it bends towards the inner surface so as to give a rounded
shape to the upper end of the spleen. This is probably
an accommodation effect for a well-developed left hepatic
lobe, with the lower and inner part of which it is related.

(b) The ventral or right extremity is usually rounder!
and corresponds to the right ventral process seen in the
Monotremes and other Marsupials. It is connected to the
great curve of the stomach by the gastro-splenic (great)
omentum, the width of which is 4 cm., so that it is moro

14G

THE SPLEEN IX MARSUPIALS.

mobile than the superior angle. It is to be noted that the
gastro-splenic omentum does not extend to the tip of
either extremity.

(c) The left extremity corresponds to the left process
seen in other Marsupials and in the Monotremes, and is
related to the outer margin of the left kidney about the
middle.

Margins. — (a) Right (anterior of human) lies be-
tween the superior and right extremities along the great
curve of the stomach. It is thin, usually concave, fre-
quently notched below, and formed by the body and right
ventral process.

(b) The left margin extends between the right ventral
and the left extremities. It is usually thin, is the longest
of the three, and presents a well-defined notch about its
middle or towards the left, so that the left process or
extremity becomes differentiated off. It is free and
comes into relation with the distal colon and the left por-
tion of the stomach.

(c) The renal or dorsal margin extends between the
superior and left extremities, being formed by the body
and left posterior process. It is thicker and more dorsal
than the others and is curved — being in relation with the
outer convex margin of the left kidney.

Surfaces. — (a) The outer or left surface is usually
smooth, slightly convex, corresponding to 8, 9, 10, 11, and
12 ribs. It is related to the diaphragm and the mesial or
visceral surface of the left lobe of the liver.

(b) Inner, right or visceral surface is more complex
and presents, as in the human spleen, certain very definite
areas, viz. right, gastric, or upper; left, lower, or colic;
dorsal or renal. The attachment of the gastro-splenic
omentum extends on the gastric surface close to the pos-

147

QASTfifO-SPLENIC FOLD

GASTRIC

Superior
ex bremiCy

RENAL

*>,dge

LlBNO RENAL FOLD

with Pancreas

Left ..
extremity

Right
exCremi L'y

INTESTINAL

SPLEEN . WOMBAT.

(Phasco/omysj

Inner or Visceral Surface of the Spleen of Wombat.

148

THE SPLEEN IN MARSUPIALS.

terior boundary obliquely down and forward from within
1 cm. of the superior extremity to within 1 cm. of the tip
of the right ventral extremity below. The lieno-meso-
colic fold — which supports the left pancreas and the chief
vessels — is attached on this aspect of the left process, and
may or may not extend to the left angle or tip. Below it
is attached to the ventrum of the caudal pole of the left
kidney, so that it is lieno-renal. The left pancreas — ■
unlike the human — can be raised from the front of the
kidney. By means of this fold and the anterior part of
the gastro-splenic omentum the lower or colic surface is
defined. In addition, certain ridges are noticed on this
aspect of the spleen. Along the attachments of the lieno-
mesocolic and anterior parts of the gastro-splenic mem-
branes is a blunt ridge, and following the curve of the
upper part of the gastro-splenic membrane a slight
ridge may be noticed. Dorsal to the upper part
of the gastro-splenic membrane is a sharper ridge —
renal ridge — the result of renal pressure, and separating
off the renal and gastric surfaces. The renal ridge is
traced along the left extreinhw, forming a prominence
below.

(1 ) Gastric surface (right or upper) is somewhat tri-
angular and concave for the fundus of the stomach. It
corresponds to the body and right anterior process.
Dorsally is the attachment of the gastro-splenic omentum
with some small vessels, and below it is separated from
the colic surface by the gastro-splenic membrane in front
and the lieno-mesocolic behind. The pancreas, supported
on the lieno-mesocolic fold, tends to encroach on the
gastric surface between this fold, the renal ridge, and the
gastro-splenic omentum. The dorsal limitation of this
surface is the ridge behind the gastro-splenic omentum;
or where the depression for the kidney is well marked a
defined margin separates it from the renal surface.

149

THE SPLEEN IN MARSUPIALS.

(2) Left, lower, or colic surface. — This is separated,
from the gastric surface by the gastro-splenic omentum,
and from the renal and gastric by the lieno-mesocolic fold
with pancreas, and more posteriorly the renal ridge, since
the renal concavity extends to the left extremity. A well-
defined fissure is seen a little below its middle, which,
extending inwards, serves to define the left process. This
surface corresponds to the right ventral and left dorsal
processes of the Platypus, the notch on the edge leading
to the fissure representing the original interval between
the two. It is related to the distal colon, and when dis-
tended the stomach is seen to be related to the upper or
ventral half (i.e. above the fissure), which portion is in-
cluded in the gastric surface of the human.

(3) Dorsal or renal surface is the narrowest of all
the surfaces and corresponds to the body and left posterior
process. It is really a concavity for the upper part of the
left kidney, and can be regarded as an accommodation
effect. The concavity may extend almost along the whole
length or be only limited to the lower four-fifths, since in
cases with a well-developed left hepatic lobe the upper
end of the spleen may be curved over towards the inner
surface. The result of renal accommodation or pressure
is to define on the inner and dorsal aspect of the spleen a
ridge or margin — renal ridge — best defined below, where
it forms a distinct projection or angle. This ridge
separates the renal and gastric surfaces and, with the
lieno-mesocolic fold, the renal from the colic below.

Interpretation of the Foregoing Facts.

A study of the spleen in these two orders throws light
on the significance of shape of the human spleen and on
the correlations associated with its fixation in the left
hypochondrium. The spleen of the Wombat (Phasco-

150

THE SPLEEN IX MARSUPIALS.

lomys) (page 148), though conforming more to the primi-
tive Mammalian type, yet resembles the human so closely
as to be at times almost indistinguishable, and so the so-
called anterior, posterior, and superior angles of the
human spleen become significant. These all have their
prototypes in the Platypus. Two spleens are illustrated,
taken at random from full-time fetuses (page 154). As
one might expect, the anterior process (/ e. ventral, right
process of the Platypus) is well defined, while the pos-
terior (i.e. dorsal, left process of the Platypus) is poorly
defined. In both, fissures are seen defining the body from
the processes. From the point of view of biology, i.e.
function, the human spleen of the text-books cannot be
accused of affording much information. Post-mortem
examinations made for a period of six years with Dr. S.
Strachan at a benevolent home for the aged showed me
the great relative frequency of perigastric adhesions,
perisplenitis, and old left pleuritis, all of which would
profoundly modify shape. To throw light on the signi-
ficance of shape it would be better if young subjects were
chosen. One naturally wonders whether different por-
tions of the Mammalian spleen have different functions.
There is no biological evidence of this, nor can it be said
to Vse borne out by histological examination, although
important differences were noted in the spleen in the dif-
ferent members of the orders described. As regards the
fixation of the human spleen, this, it must be borne in
mind, is associated with fixation of the distal colon and
left pancreas. The attempts made by nature can be
studied in the Monotremes and Marsupials. In a study
of the peritoneum of the members of these two orders,
three primary folds are noted, which are traced in vary-
ing degree throughout the Mammalia, and play an im-
portant part in the fixation of the gut, which is coadjusted
to the erect posture: —

151

THE SPLEEN IN MARSUPIALS.

(1) Mesial fold, approximating the colon to the
pyloric region, and continuous in the Chameleon with the
gastro-hepatie omentum or ventral mesogaster.

(2) Duodenal or right lateral, passing from the
ascending duodenum to the right aspect of the mesocolon

of the distal colon, which I regard as an acquired or phy-
siological fold (zygosis).

(3) Left lateral or Iieno-mesocolic, from the left,
dorsal, or posterior process of the spleen to the left aspect
of the mesocolon of the distal colon. The mesial fold is best
defined in the Koala, the duodenal in Trichosurus, and
the lieno-mesocolic fold in the Platypus and Dasyures.
The origin of the left lateral or lieno-mesocolic fold was
certainly very puzzling, and at first I was inclined to
regard it as an acquired or physiological adhesion (zy-
gosis) from a spleen which had wholly developed in
relation to the lesser sac. A study of certain lizards
supplied me, however, with a different explanation (page
154).

In Agama we notice the narrow splenic body in the
mesogaster running parallel with the stomach. In Lygo-
soma (Scincidae) the spleen was noticed passing almost
vertically close to the dorsal wall and in relation not only
with the mesogaster but with the mesentery and meso-
colon as well. Correlated with the development of the
Mammalian spleen we have the development of great
omentum, and, in the case of the Agama, the enlargement
would be wholly related to the lesser sac, as actually
happens in Koala, in which the left process is insignifi-
cant : while in the case of Lygosoma an enlargement of the
spleen would involve not only the mesogaster (great
omentum, lesser sac) but the mesocolon as well. In
Lygosoma the pancreas is noted as a single strand ex-
tending from the commencement of the duodenum to the

15*2

THE SPLEEN IX MARSUPIALS.

lower portion of the spleen. Divisibility is characteristic
of its early Mammalian development. In the Platypus it
diffuses itself on the right in the meso-duodenum and on
the left on the lieno-mesocolic fold. Mesially it is fixed,
forming the lower dorsal boundary of the lesser sac.

With development of the spleen is a correlated great
omentum, but no inclusion primarily by the great omen-
tum (lesser sac) of distal colon or pancreas. The pan-
creas as we ascend in the Mammalian scale becomes more
compact. From the point of view of selection it would
not be advantageous for it to be included in the lesser sac.
It could not then conform to the abdominal law of dorsal
fixation of solid bodies by which torsion especially of
ducts is prevented in the erect posture. In addition, the
dorsal fixation of duodenum, spleen, and left distal colon,
of which its own further dorsal fixation is an important
factor, would be interfered with; and the significance of
the relationship of the pancreas on the left to a fold (left
lateral) connecting spleen and distal colon in the produc-
tion of that arrangement becomes understood. This fold
is completely absent in Koala, and in that Marsupial
there is no fixation of distal colon, spleen, or left pancreas.
Primary inclusion by the great omentum of the proximal
8 cm. of distal colon actually happens in Pseudochirus
(Australian Phalanger), and in this Marsupial, though
distal colon, spleen, and kidney are proximal, there is a
considerable amount of pancreatic tissue free in the lesser
sac. Furthermore, a studv of the Mammalia shows that
for adaptability to a mixed diet selection requires not
atrophy but development of the distal colon, which be-
comes ultimately fixed as in erect Man in the left hypo-
chondrium. In the Echidna, whose diet is chiefly ants, a
failure to develop or atrophy of the distal colon and meso-
colon is correlated with the dorsal fixation of that gut
and of the pancreas, but not of the spleen. I regard that
as the evolutionary tendencv in the Echidna (since I have

153

RENAL. SURFACE.

£T POST. PPOC

GAJTPO-SPLC'C
G ' OMENTUM

PTANTfPOC

LrENO MESOCOL/C POLO
f L.T L.A TEPAL )

opossum . (tpichosupus)

R7 Ant , paoc

lt post ppoc

rta.nt. ppoc.
YOUNO ORANCi,

RENAL. SUP-

Lt POS T PPOC

risSUftng"

rt ant: ppoc
opossum (tpichosupus)

Reival. Sup

lt post ppoc.

YOUNG BABOON.

fisturmp'

RT ANT PRQC-

issur-m c

i_T post ppoc

R"' ANT PPOC ■
«-T POST PPOCi

HUMAN FOETUS. (FULL TIME)

Spleens of Phalantjer (Opossi m), Orang., Baboon., and Human

Foetuses.

PYLORU 3

PANCREATIC STRANDS

r~=~' MESOQASTER

SPLEEN

(Agama '

PA ZEN

OS O/TT a

S. Gut loop

DORSUM

MESOCOLON

MESENTE.RY

Diagram to show Contrasted Positions of Spleen in Agama am

Lygosoma. .

154

THE SPLEEN IN MARSUPIALS.

seen the various grades of shortening of the mesocolon),
and nature does not retrace her steps. From the point
of view of "selection" for the evolution of the human
type, the arrangement in the Platypus is superior to that
of the Echidna.

The "selection" factors would he: —

(a) Lieno-mesocolic fold lying ventral to left

kidney, connecting spleen and mesocolon,
and supporting pancreas.

(b) Pancreas outside the lesser sac.

splenic omentum) between the left extrem-
ity of the spleen and stomach fundus, with
secondary peritoneal bands between the two.

(d) Development — not atrophy — of the distal

colon.
As evolution proceeds, the pancreas, which even in the
Platypus is fixed dorsally about the root of the mesentery,
approaches the dorsum on the right and left sides (in the
Echidna direct adhesions may be noted between pancreas
and lobus caudatus), which means some approximation of
spleen and mesocolon. Adhesions form between the lieno-
mesocolic fold and ventrum of the left kidney as in
Triehosurus — the fold ending in the Wombat at the lower
pole of the kidney. Thus is developed the lieno-renal
band. The development of the so-called human "inter-
mediate" angle (which really represents the lower limi-
tation of the renal ridge) is now easy to understand.
Further evolution results in further atrophy or shorten-
ing of the lieno-renal (mesocolic) fold. The pancreas
and colon become more closely related to the spleen,
with an encroachment on the lower portion of the renal
concavity and atrophy of the lower part of the renal

ridge.

155

THE SPLEEN IX MARSUPIALS.

A new feature becomes added which can be effectively
studied throughout the Primates, viz. the inclusion by
great omentum first of the mesocolon and later of the
distal colon — the pancreas now being a dorsal organ.
This inclusion or fusion begins from right to left, and the
importance of the mesial fold previously mentioned,
between the colon and pyloric region, is seen. Early
phases of this can be studied in Macropus. In a young
Baboon (Oatarrhina ) (page 154), the iklieno-mesocolicv
is simply a fold between the spleen and the upper part of
the kidney, i.e. it is atrophying, and the ridge on the inner
surface of the posterior angle or process has almost gone.
The lower part of the renal and the colic surfaces are be-
coming continuous with the " intermediate'' angle be-
coming evident. Here, however, the colon is not fixed,
but the mesocolon at its commencement is partially
applied to the great omentum. The colic surface is not,
as in the human spleen, encroached on by the stomach, i.e.
the relationship of colon to spleen is not limited as in the
human, and the gastro-splenic omentum goes almost to
the tip of the anterior process. In a young Orang Utang,
however (p. 154 ), the color is fixed dorsally. It is included
(secondarily) in the lesser sac by the great omentum,
and has only a limited relation to the spleen. The anterior
portion of the colic surface is encroached on by the
stomach as in the human spleen. Thus, with its fixation
the colon comes into relation with a limited area of spleen
only, though previously related to the whole colic surface.
As to whether the stomach will encroach on the colic sur-
face depends on the atrophy of the right or anterior part
of the gastro-splenic omentum. With dorsal fixation of
the spleen the membrane further atrophies and the
stomach encroaches as in the human spleen. But where
there is mobility, i.e. not good dorsal fixation, the anterior
part of the lower surface is colic not gastric. Thus we

156

THE SPLEEN IN MARSUPIALS.

may see the human foetal spleen with the remaining lieno-
mesocolic (renal) fold and the anterior part of the gastro-
splenic omentum extending to the extremities of the
anterior and posterior processes, and practically shutting
oft' the lower surface which is related to colon only. This
is associated with a greater amount of mobility than is
present in the human adult spleen.

It is worthy of note that broadening of the base of the
mesentery, i.e. fixation of the proximal colon, begins from
the mesial fold also, spreading from above downwards.
Similarly, further fixation of the distal (descending)
colon spreads downwards from the splenic fixation or
flexure. The supporting phrenico-colic fold and the sus-
pending lieno-phrenic, also lateral processes from the
spleen to the abdominal wall, are adaptive physiological
membranes freelv modified to meet local conditions.

15<

NOTES

Varleys Pty. Ltd., Printers, Melbourne.

737

M3M33

1918

C.l

BMED

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Full text of "The liver, spleen, pancreas, peritoneal relations, and biliary system in monotremes and marsupials"

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