INTESTINAL DIGESTION. 63 



cretory substances are here thrown out on the surface of 

 the intestinal tube, and it now becomes excrement or 

 faeces. These excrements, compressed by the peristaltic 

 contractions of the muscular coat, are rolled up into little 

 rounded masses, shoved into the rectum, and in due course 

 expelled. 



The rectum (G) appears to be merely the extremity of 

 the small colon. 



1. INTESTINES OF RUMINANTS. The small intestine 

 of the ox is folded in a multitude of festoons, is twice the 

 length of the small intestine of the horse averaging about 

 120 feet and is about one-half the size. The large intes- 

 tine is about 30 feet in length, but is less in size than that 

 in the horse. In the sheep the small intestine is about 70 

 feet long, and the large intestine 20 feet. Neither in the . 

 ox or sheep is there such a marked distinction between the 

 small and large colon as in the horse. 



2. INTESTINES OF THE PIG. The average length of the 

 small intestine of the pig is 72 feet, and the large intestine 

 18 feet. Their general disposition in the digestive cavity 

 is somewhat similar to those of the ox, though only the 

 last portion of the colon is included between the layers of 

 the mesentary ; for the rest of its extent it is outside that 

 membrane, and forms a distinct mass. 



The small intestine has a very large peyerian gland, oc- 

 cupying the latter portion of the canal as a band 5 to 6 feet 

 long. This is an aggregation of secretory follicles. The 

 pig is noted for its capacity to digest and assimilate a very 

 large amount of food in proportion to its weight of body. 

 Its alimentary canal shows how this large amount of con- 

 centrated food is prepared and assimilated. 



Lawes and Gilbert made many interesting experiments in 

 feeding oxen, sheep, and pigs, and they found that the pig 

 utilized his food better than either of the other classes of 



