VETERINART DENTAL SURGERY. 49 



invades the tooth structure and changes it into a 

 material which can be taken up by the natural chan- 

 nels of the part. In caries the softening is caused by 

 the chemical decomposition of the calcified tentures 

 of the tooth-structure, and is accompanied by putre- 

 faction and the presence of micro-organisms. In 

 physiological absorption there is simple removal of 

 the softened tissues without the occurrence of putre- 

 faction or the presence of micro-organisms. Further 

 researches in the domain of absorption of the hard 

 tissues, and especially those of the deciduous teeth, 

 are greatly needed, and it is to be hoped that from 

 such studies the obscure points in relation to the 

 physiological removal of the hard tissues may be 

 elucidated." 



