thereto by a progressively decreasing breadth of non-serous wall:

the gut then resumes a complete
serous coat, which passes off
into the progressively widening
duplicature of peritoneum, for-
ming the mesocolon:' nearing
the duodenum it arches across to
the left, TC, at the line between
the umbilical' and epigastric'
regions of Anthropotomy: then,
descending ventrad of the left
kidney and quadratus lumbo-
rum,' it becomes attached thereto
by areolar tissue: it next forms
the folds called 'sigmoid flexure;'
ib. s F; and, bending to the
mid line, contracts and passes
as the rectum,' R, to the vent.
Save at this terminal portion, d
the longitudinal fibres of the
large intestine are specially ag-
gregated along three nearly
equidistant tracts, one of which

344

345

runs along the line of attachment of the mesocolon: these bands' are nearly one-half shorter than the entire gut, and consequently pucker it up into sacculi. They commence at the setting on of the vermiform appendage and diverge therefrom to their positions on the cæcum and colon: at the sigmoid flexure they begin to expand and form, with added fibres, a strong continuous longitudinal stratum upon the rectum. The circular fibres, uniformly thin and feeble upon the colon, are thickened round the rectum. The human vermiform appendage,' fig. 345, g, is commonly from 4 to 5 inches in length: its diameter is about 4 of an inch: the follicular glands are so numerous as to constitute sometimes a continuous layer. The ileum, ib. a, opens by a transverse slit into the inner or mesial side of the cæcum, c: the opening being defended by a pair

346

of semilunar valvular folds, of which the lower, f, is the ileocæcal,' the upper, e, the 'ileo-colic' valve. A transverse constriction, d, usually marks the boundary between cæcum and colon. In the apes and all lower quadrumana the ileo-cæcal orifice and valve are circular. The mucous membrane of the cæcum and colon is the seat of both intestinal tubules and follicles: the latter are chiefly present in that of the rectum, which is disposed in numerous folds. Although this gut appears straight in a front view, it follows, in Man, the curve of the pelvic cavity, through which it passes, as shown in the side view, fig. 346. The peritoneum is reflected from its upper third, forming the recto vesical' pouch, ib. r, v; and the rest of the gut is Section of Human pelvis, showing course of rectum. attached by the ordinary areolar tissue to the surrounding part.

CXLVIII".

Anthropotomy accordingly distinguishes, in the rectum, an upper or oblique segment,' s, r 1: a middle or arcuate segment,' r 2, and a terminal portion,' r 3: inclosed at the end by the sphincter ani,' q, n.

347

§ 331. Alimentary canal of Carnivora.-In this group the digestive system is adapted, as a rule, exclusively for animal diet. The oesophagus is usually wide. The muscular fibres are arranged in an external longitudinal and an internal transverse layer: but, in the Lion, a third layer of longitudinal fibres is applied to the inner side of the circular ones at the terminal part of the tube: they are separated from the circular fibres by loose areolar tissue; and are

closely attached to the lining membrane of the esophagus, which they, here, pucker up into numerous narrow alternating

transverse rugæ. The stomach of the Lion, fig. 347, shows its common form in the order: it is chiefly elongated from right to left; but lies less transversely to the abdomen than in Man: the cardia, a, and pylorus, b, are wide apart: there is but a small extent of blind sac,' d, to the left of the cardia, and the pyloric end, e, b, is bent abruptly and closely upon the middle of the stomach. The longitudinal fibres of the muscular coat form a strong band along the lesser curvature: the rugæ of the inner coat affect a longitudinal course: the pyloric valve is less prominent than in man. The branches from the arteria coronaria ventriculi' pass some way down the front wall before penetrating the gastric coats; not entering at the lesser curvature, as in Man. In all Felide the pylorus is suspended by a duplicature of peritoneum, and the duodenum has the same loose attachment, to its termination, which becomes more closely tied to the vertebral body. The mesentery again expands to suspend the rest of the small intestines. In a full grown Lion these measured 18 feet, with a uniform circumference of 24 inches. The cæcum was 2 inches long: it is simple and conical, fig. 348: the length of the large intestines was 2 feet 10 inches; the colon soon gains a circumference of 4 inches. The muscular coat of the intestines is thick throughout. The terminal orifice of the ileum is circular, and situated on a valvular prominence of the same form. The apex of the cæcum is a cluster of intestinal follicles.

348

اتی

Cæcum of the Lion

The lining membrane of the small intestine has fine and closeset villi in the Lion; they are longer and coarser in the Bear, and seem to be rather flattened than cylindrical. In contracted parts of the tube the lining membrane is thrown into longitudinal ruga: the agminate follicles form long longitudinal tracts in the Lion. In the Hyæna the cæcum is about twice the length of that in the Lion, relatively.

In the Dog the gullet extends about two inches beyond the diaphragm before terminating in the stomach. The duodenum is loosely suspended by a mesentery, except at its transit across the vertebræ to become jejunum. The cæcum is relatively longer than in the Hyæna, and after a short course is folded or curved. The intestinal canal is longer and narrower in the Dog than in the Wolf, and the cæcum in the latter is curved from its origin: it has three coils in the Fox.

The rugæ of the gastric membrane are numerous and well

marked in the contracted stomach of the Dog.

Microscopic investigation of the gastro-mucous coat has shown the tubules to be more commonly subdivided at their blind ends than in Man. In fig. 349, A is a tubule from the cardiac half, and B one from the pyloric portion, of a Dog's stomach: a, b the columnar epithe

one of the villi, b, from which the columnar epithelium, a, c, is partly detached: d, e, are columnar cells, more magnified, showing the nucleus. Some of the Civet tribe have a stomach of a fuller

Stomach, duodenum, and pancreas, Suricate nat. size shape, maintaining much

width to near the pyloric end, c, which is too short to be bent. The duodenum, d, d, makes a large curve, and is a loose intestine, with a meso-duodenum which becomes shorter as it approaches the spine at the lower end of the curve:

it is continued into the jejunum before

crossing the spine. The biliary and pancreatic ducts, d, terminate about an inch from the pylorus. The length of the small intestines is 3 feet 2 inches, with a general circumference of one inch.

The cæcum,

fig. 352, c, is an inch in length, rather contracted at the neck, with an obtuse blind end: this is occupied by a patch of agminate follicles: a larger patch is at the end of the ileum, ib. a: the ileo-colic orifice and valve, b, are circular. The colon, d, is continued almost straight to the vent, e: the length of the large intestine was but 6 inches.

352

d

7

Large intestine, Suricate, half nat. size.

The Musteline, Subursine and Ursine Carnivora are, as a rule, devoid of cæcum. In the Martin (Mustela martes) the intestinal canal is three and a half times the length of the body. In the Otter the great and small curves of the stomach appear angular through the abruptness of the bend of the pyloric upon the cardiac part. The intestinal canal is relatively longer in Enhydra than in Lutra. In the Racoon the beginning of the colon is indicated by a slight enlargement and circular fold of the lining membrane, not produced so as to form a valve. In a Benturong (Ictides) I found a cæcal projection of half an inch in length at the beginning of a large intestine two feet in length: the small intestines were seven feet long; the length of the animal, exclusive of tail, was two feet. The stomach of Ailurus is subglobular, with terminal orifices; the narrow termination of the pyloric part has a thick mucous membrane. In the Bear there is a more marked blind sac at the left end; both muscular and mucous coats are thick. The villi of the small intestine are longer and coarser than in the Lion. In Urside the entire intestines are about twelve times the length of the body; in Felide from three to four times; in Viverride from four to six times: the longest in this family being in the frugivorous Palm-cats (Paradoxurus.)

In the common Seal (Phoca vitulina, L.) the oesophagus opens