The Digestion of Food 



Next behind the* canines follow, on each side, two 

 bicuspids. The three hindmost teeth in each jaw are the 

 molars, or grinders. The last molars are known as the 

 "wisdom teeth" (Figs. 46 and 51). 



X152. Development of the Teeth. The teeth just described 

 are the "second," or permanent set, which succeeds the tem- 

 porary, or milk teeth. The latter are twenty in number, five 

 on each side of each jaw, that is, two incisors, one canine, 



FIG. 46. Temporary and Permanent Teeth together. 



Temporary teeth : A, central incisors ; B, lateral incisors ; C, canines ; >, anterior 

 molars ; E, posterior molars. Permanent teeth : F, central incisors ; ff, lateral 

 incisors ; K, canines ; , first bicuspids ; M, second bicuspids ; N, first molars. 



and two molars. The milk teeth appear during the first and 

 second years, and last until about the sixth or seventh year, 

 from which time until the twelfth or thirteenth year they are 

 gradually pushed out, one by one, by the permanent teeth. 

 The roots of the milk teeth are muchr.smaller than those of 

 the second set. 



153, Structure of the Teeth. If we should saw a tooth 

 down through its center we should find in the interior 



