434 THK HORSE. 
become more and more rare towards the rectum. At the commencement 
the gut is enlarged to an enormous size, and forms a cul de sac called the 
cecum, which is about four feet long, and terminates in a point, the 
whole being compared to a jelly bag, and forming a reservoir, where the 
watery particles of the food are absorbed, leaving the fecal matter in a 
comparatively solid state. Indeed this gut at once receives nearly all the 
water which is swallowed, it passing through the stomach and intestines 
without any delay, when of course, as this sac has only one opening, it 
must alternately receive and disgorge its contents, the valve at the 
entrance of the ileum preventing its return into the small intestine. The 
coecum occupies the right flank, and takes an oblique direction from above 
downwards and forwards. 
THE COLON extends from the ileo-ccecal valve, occupying the right 
flank, in an elliptical direction to the left flank, where it ends in the 
rectum, and thus ends very near the point where it began, after traversing 
nearly the whole abdominal cavity. It is of such an enormous capacity, 
that it will hold from twelve to thirteen gallons of water. Its largest 
diameter is at the commencement, from which it begins to contract, and as 
it crosses from the right of the abdomen near the liver to the other side, 
where it is in close proximity to the stomach, it is contracted to a com- 
paratively small diameter, but enlarges again as it lies in the left flank. 
Like the cecum, it has three longitudinal muscular bands for three-fourths 
of its course, but these afterwards are reduced to two, and as it merges in 
the rectum they disappear altogether, the longitudinal fibres being then 
equally distributed. The ccecum and colon are supplies with blood by 
the posterior mesenteric artery. 
THE RECTUM, or straight gut, begins on the margin of the pelvis, from 
which it extends in a straight line to the anus. It gradually expands to 
form a considerable reservoir for the feeces, and is uncovered by peri- 
toneum after its commencement. 
THE LIVER. 
THIS IMPORTANT organ is in close contact with the right side of the 
diaphragm. It is of anirregular figure thick in the middle and thin at the 
edges ; divided into three lobes ; convex on its anterior surface, where it is 
adapted to the concave aspect of the diaphragm; concave posteriorly. 
The colour is that which is so well known, and peculiar to itself. It is 
everywhere invested by the peritoneum, excepting the spaces occupied by 
the large veins as they enter and pass out, and the coronary ligament 
which suspends it, as well as the three other folds of peritoneum, which 
have also received particular names. 
THE strucTURE of the liver is most peculiar ; but it will be impossible 
to enter fully into its minute anatomy for want of space. Suffice it to 
observe that it is composed of lobules, of an areolo-fibrous connecting 
medium (which has received the name of the capsule of Glisson), of the 
ramifications of the vena porte, hepatic artery, hepatic veins, hepatic 
duct, lymphatics and nerves, inclosed in the investing peritoneal coat. 
The portal vein returns the blood from the stomach and small intestines 
to be circulated through the lobules, and from this the bile is secreted. 
It distributes its numberless branches through canals which are every- 
where worked out in the substance of the liver, and from which the 
lobules are supplied. From these, which are each a small gland perfect 
in itself, the bile is received by a network of minute ducts, ultimately 
, 
