74 I 'E TEH IX. I A' T DE\ T. \L SI Yi'f iE A' ) '. 



the same mouth, and in many instances these only 

 at particular points. Such conditions are peculiarly 

 favorable for the attack of caries. When the 

 whole crown of the tooth is imperfectly organized, 

 the decay will progress with uniform rapidity under 

 the influence of uniformly persistent agents till the 

 whole is destroyed. But when it is only a portion 

 of the tooth, the caries may after a time become 

 retarded in its progress, and in some cases checked 

 altogether. 



By making an examination of the teeth of a 

 large number of horses which were destroyed for 

 dissection, the latter condition referred to was fre- 

 quently found present. In some subjects teeth were 

 found with a central depression on the table surface, 

 which extended to a variable depth and to all ap- 

 pearances were perfectly free from any carious 

 particles. In others small specks of decayed, earthy 

 material were noticed on the sides of the cavities 

 while the bottom of them was perfectly sound. 

 Every gradation from a perfectly healthy to a 

 completely diseased cavity has been noticed. 



In examining the teeth of living animals I have 

 often found the same condition present. 



Among the many circumstances which modify 

 the progress of this disease, are a change in the 

 character of the agencies producing it, as well as an 

 increase or diminution of the amount of such agen- 



