THE DIGESTIVE SYSTEM. 73 



The whole process of preparing food material for the 

 blood is called digestion. The first step, that is, 

 bringing the food into the mouth, is called prehen- 

 sion. 



The second step in digestion is masti- 



Teeth * the cation ' This is performed in the mouth 

 by the teeth. The mouth and the teeth, 

 as used in chewing or masticating the food, have 

 been called the mill of the body. The grinding in 

 this mill is done by the muscles which move the 

 jaws so as to produce a cutting, crushing or grind- 

 ing effect upon the food by the teeth. 



There are thirty-two teeth in the full 



Teeth* 1 " f se ^ ^ a g rown P erson - These are set 

 in sockets of the upper and lower jaw- 

 bones sixteen in each jaw. Eight front teeth 

 four in each jaw are called incisors, or cutting 

 teeth. On each side^ of these incisors above and 

 below is a canine tooth. The two upper canines 

 are often called eye-teeth, and the lower canines, 

 stomach-teeth. These twelve teeth eight are incis- 

 ors and four canines separate or bite off a proper 

 portion from the food which is brought to the mouth. 

 Next to the canines are two bicuspids, on both sides 

 of each jaw. Bicuspid means having two roots. 

 Then follow, as back teeth, three molars or grinders 

 on both sides of each jaw. These twenty teeth 

 eight bicuspids and twelve molars do the work of 

 crushing or grinding the food to a proper degree of 

 fineness. 



