FUNCTION AND STRUCTURE 67 
mentary canal. In some of the higher animals this is a 
very complex organ. In the cow, one of the cud-chewing 
mammals or ruminants, it consists of several distinct por. 
tions, which differ among themselves very much (Fig. 30). 
first, there is the mouth, or opening for the entrance of 
the food. The mouth is sup- 
plied with teeth for tearing 
off and chewing the food, 
with a tongue for manipu- 
sating it, and with taste pa- 
pill situated on the tongue 
and palate for determining 
the desirability of the food. 
Into the mouth a peculiar 
fluid (the saliva) is poured 
by certain glands, organs ac- 
cessory to the alimentary 
canal. The herbage bitten 
off, mixed with saliva, and 
rolled by the tongue into a 
ball, passes back through a 
narrow tube, the esophagus, 
and into a sac called the ru- 
men, or paunch. Here it 
jes until the cow ceases for 
the while to take in food, 
when it passes back again 
through the esophagus and 
into the mouth for mastica- 
tion. 
Fie. 30.—Alimentary canal of the ox 
(after CoLin and MOLLER). a, rumen 
(left hemsiphere) ; 6, rumen (right hem- 
isphere) ; ¢, insertion of esophagus ; d, 
reticulum ; ¢, omasum; /, abomasum ; 
g, duodenum; / and i, jejunum and 
ileum; j, cecum; &, colon, with its 
various convolutions ; 7, rectum. 
After being masticated it again passes downward 
through the esophagus, and enters this time another sac 
called the reticulum, lying next to the rumen. 
From here 
it passes into another sac-like portion of the alimentary 
canal called the omasum, where it is strained through 
numerous leaf-like folds which line the walls of this part 
of the canal. From here the food passes into a fourth 
