109 



be obtained after the sixtli year. This limitation, 

 coupled as it is with a confession of inability, may 

 seem to be a backward movement ; but truth cannot 

 retrograde. By ascertaining how far our present 

 knowledge leads us, a motive is given to genius by 

 the opportunity created for its exercise. No pains 

 have been spared to investigate the hypotheses which 

 have been made known ; they have been candidly 

 put to the test, and on the proof of their inefficiency 

 discarded. That the reader may judge for himself, 

 the tables of teeth, and mouths of various ages are 

 presented. The altered aspect of the tables at the 

 ninth year is indicated in the following wood- cut, 

 which exhibits these surfaces as gaining depth and 

 narrowing from side to side. This appearance they 

 generally assume, and at the same time the in- 

 fundibula are either lost or much contracted. 



The next wood-cut, which depicts the form of the 

 tables at the tenth year, though true in its general 

 character, will serve to show how far dependance 



