CHAP, vi.] THE CAT'S ALIMENT AEY SYSTEM. 183 



which projects blindly (whence its name) beyond the point at which 

 the small intestine opens into the ascending colon. It is a short, 

 wide, simple, rather conical part, narrowing rapidly to its apex, but 

 having its terminal portion more or less sharply bent towards the 

 ileum, and separated off from the rest by a slight constriction so 

 that it forms a sort of appendix to the rest of the caecum. This 

 terminal portion is thick-walled and glandular, being lined by a sort 

 of Peyer's patch. The entrance from the ileum into the cajcum is 

 by a circular constriction (with its margin prolonged somewhat into 

 the caecum) called the ileo-ccecal valve. 



There are many glands in the rather thick walls of the crccum, 

 especially towards its apex. 



On each side of the hinder end of the intestine are two large 

 secreting pouches, or ANAL GLANDS, each of which would contain a 

 very large pea within its cavity. They are both embraced and 

 invested by the external sphincter muscle, and are lined by glandular 

 mucous membrane. Each gland opens externally just within the 

 margin of the anus by a short duct, the inner end of which projects 

 inwards into the cavity of the gland, of which it is the excretory 

 channel. 



The structure of the large intestine essentially resembles that of 

 the small. It exhibits irregular internal folds in the descending 

 colon, and in the rectum ; and there are numerous follicles scattered 

 throughout its whole extent, but its surface is not raised into 

 processes or villi. There is thus a great contrast between its 

 interior and the villous internal surface of the small intestine. 



The FUNCTION of the large intestine is in great part mechanical. 

 By its contractions its contents are driven onwards to the rectum, 

 whence they are expelled by the contraction of the rectal walls and 

 the simultaneous relaxation of the sphincter ani the expulsive 

 action being aided by the contraction of the muscular walls of the 

 abdomen, and the backward pressure of the diaphragm. The power 

 of absorption of this part of the alimentary tube is much less than 

 that of the small intestine, as is evidenced by the absence of villi. 

 Nevertheless it does possess a certain power of absorption, and it 

 not improbably also serves to extract from the blood, and cast forth 

 into the intestinal cavity, some substances, the removal of which is 

 beneficial to the organism. 



17. The PANCREAS (Fig. 90, B) is a large, racemose gland, 

 composed of, and entirely invested by, peritoneum. It consists of 

 lobes and lobules of different sizes, connected together by areolar tissue, 

 vessels and ducts, being in fact like the parotid gland, but somewhat 

 looser in structure. In shape it is elongated and narrow, and is 

 indistinctly divisible into two parts. One portion of it, the body, 

 lies posterior to and above the posterior border of the stomach 

 (enclosed between the layers of the posterior fold of the great 

 omentum) on the right ; the other and larger part, the head, passes 

 backwards along the concave margin of the duodenum. It has two 

 ducts ; one of these joins the common bile-duct (from the liver) 



