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 the most of absorption 
Fig. 58 .—section of the Wall of takes place. The large intestine is 
the Human Intestine ( ileum ), . . 
x 50: a,villi; bandd,glands; mainly a temporary lodging-place 
c and e, mucous membrane; /, r „ ,1 , i 
circular muscles; g, h, longi- lor the useless part of the food, 
tudinai muscles. until it is expelled from the body. 
The beginning of the small intestine is called the duode¬ 
num ., into which the ducts from the liver and pancreas 
open. The intestinal canal has the same structure as the 
stomach, and by a peristaltic motion its contents are pro¬ 
pelled downward. The inside of the small intestine is 
covered with a host of thread-like processes (villi), resem¬ 
bling the pile of velvet. 
