40 ANIMAL SKETCHES. CHAP. 



Then again the teeth. The teeth in these three 

 animals are as different as they well can be. Yet they 

 show us modifications of a single definite system, though 

 the modifications in the case of the elephant have certainly 

 been pushed to extremes. In our own mouth we have the 

 front teeth or incisors, two on each side of the middle line 

 in each jaw (feel for them, if you please with your 

 tongue). Then come the eye-teeth, or canines, which are 

 often larger in savages than in civilized folk, and form 

 cruel fighting weapons in some of the apes. Behind 

 these again are the grinding teeth. We have two sets of 

 teeth the early set of milk teeth, and the later set of 

 permanent teeth. As the latter grow they press on the 

 roots of the milk teeth, and cause the part embedded in 

 the jaw to be absorbed ; and from this absorption the 

 early teeth become loose, and at last can be pulled out 

 quite easily. To these two sets the kindly dentist in our 

 old age often adds a third, which have the advantage of 

 never aching. They used to be made of hippopotamus 

 ivory, which does not, like that of the elephant, turn 

 yellow. So there is a closer connection between Stumpy's 

 teeth and your grandmother's than you suspected. 



Now let us turn to Stumpy's jaws. He will open them 

 wide for you to pitch a bun on to that great pink tongue 

 of his. You probably will not be able to see the grinders, 

 which form nearly parallel series of seven teeth, all told, 

 in each jaw and on each side. When they first cut the 

 gum they present a number of rounded projections, giving 

 them a hilly appearance such as you may see in the jaw- 

 bone of Stumpy's second-cousin-once-removed, the pig. 

 But the work of grinding down the coarse vegetable food 

 wears off the summits of the hilly prominences and dis- 

 plays the dentine (or ivory) lying beneath the hard 

 glistening white enamel which coats the tooth. Thus a 



