42 



AGE OF THE DOMESTIC ANIMALS. 



cavity. At first it is entirely protected by the enamel, but as 

 the table is formed it becomes exposed, and, as it is softer than 

 the other substance, becomes worn more rapidly, and renders 

 the wearing surface uneven and better adapted to grinding. 



Fig. 31. 



Transverse section of an inferior molar (right). Enlarged. 



G. The Cement is very abundant on the molars. It covers 

 the enamel, fills the infundibula of the enamel, and, in very old 

 mouths, is often formed in excess, and furnishes a new wearing 

 surface to replace the teeth themselves, which have been 

 destroyed by use. 



