98 



DIGESTION 



digestion. As soon as the human infant begins to be ac- 

 tive and to require other food than milk, his teeth 



FIG. 61. a, An incisor tooth, b, A canine or eye tooth, c, A bicuspid tooth seen 

 from its outer side ; the inner cusp is accordingly not visible, d, A molar tooth. 



push their way out through the soft gums from the bones 

 of the jaws in which they have been developing. The 

 first tooth usually comes when the baby is about seven 



FIG. 62. Teeth of dog. 



FIG. 63. Teeth ot horse. 



months old. At two years of age, he should have his 

 first et of twenty teeth. Of these, each jaw contains 



