90 



COMPARATIVE ZOOLOGY. 



hold about five pints ; that of the Kangaroo is as long 

 as its body. 



The intestinal canal in Mammals begins at the pyloric 

 end of the stomach, where there is a kind of valve or cir- 

 cular muscle. Like the stomach, it varies greatly, accord- 

 ing to the nature of the food. It is generally longest in 

 the Vegetable-feeders, and shortest in the Flesh-feeders. 

 The greater length in the former is due to the fact that 

 vegetable food requires a longer 

 time for digestion, and that a great- 

 er bulk of such food is required to 

 obtain a given quantity of nutri- 

 ment. The intestines measure 150 

 feet in a full-grown Ox, while they 

 are but three times the length of 

 the body in the Lion, and six times 

 in Man. Save in some lower 

 forms, as the Whales, there are 

 two main divisions, the " small " 

 and "large" intestines, at the 

 junction of which is a valve. The 

 former is the longer of the two, 

 and in it digestion is completed, 

 and from it absorption takes place. 

 FIG. 58. section of the waii of The large intestine is a temporary 



the Human Intestine (ileum), . 



X 50 : a, villi; band d, glands; lodging-place for the USeleSS part 



tndinai muscles. 



f the f d > tn ifc is 



f rom tne j^y. The beginning of 

 the small intestine is called the duodenum, into which 

 the ducts from the liver and pancreas open. The intes- 

 tinal canal has the same structure as the stomach, and by 

 a peristaltic motion its contents are propelled downward. 

 The inside surface of the small intestine is covered with 

 a host of thread-like processes (villi), resembling the pile 

 of velvet. 



