754 



p:xa\iination foe ag-e. 



become shorter with age ; although we sometimes find them very 

 long, and even with rearmost edge sharp, in old horses. I cannot 



Kig. 200. — A milk cen-tral incisor. A, rear view. B, front view. 

 c, profile. [FioDi Gonhaitx ajid Barrier.) 



satisfactorily explain how it is that these teeth usually wear down 

 so fast; unless the friction of the tongue is the cause in question. 



Fig. 201. — A permanent lower central incisor. A, front view. B, rear 

 view. c. profile. {From Goubaux and Barrier.) 



4. The permanent incisors grow more and more oblique, owing 

 to their shape, and position in the jaws. Consequently, the angle 



