WEARING AWAY. 



83 



fore. They appear worn not so much on the outer 

 edge or line of the tooth, as inside this line ; but, after 

 this, the edge begins gradually to lose its sharpness, 

 and to present a more flattened surface ; while the next 



Pig. 19. Five to eight months. Fig. 20. Ten months. 



outer teeth wear down like the four central ones ; and 

 at three months this wearing off is very apparent, till 

 at four months all the incisor teeth appear worn, but 



Fig. 21. Twelve months. Fig. 22. Fifteen months. 



the inner ones the most. Now the teeth begin slowly 

 to diminish in size by a kind of contraction, as well as 



