ON ABSORPTION. 23 



loped within the deciduous alveolus, endowed espe- 

 cially with the power of absorbing the old tooth ; 

 that, as fast as it encroaches upon the deciduous 

 organ, a layer of osseous tissue is developed at the 

 base, which separates it from the new tooth ; with 

 which it not only has no connexion, but that when 

 there are no successors it still continues to absorb 

 the fangs of the temporary teeth. 



In order that we may arrive at the knowledge of 

 the laws which regulate this process, it is neces- 

 sary that its progress should be observed under 

 distinct conditions, and also in different animals. 



Absorption of the teeth exhibits itself under two 

 forms, that is, normal and abnormal ; the former 

 being obedient to a natural law, the latter the 

 result of extraneous causes. Although it is the 

 former of these that it is our object to discuss, yet 

 most probably the subject will be assisted in eluci- 

 dation by the study of the latter also ; for when a 

 law is strained to meet peculiar conditions, it is 

 liable to be more distinct to our conceptions. 



We know that a blow given to a tooth, although 

 it produces no immediate result, will occasionally 

 induce aborption of the whole fang. 



Fig. 1, Plate II., represents the crown of a central 

 incisor that was so absorbed. It received a severe 

 blow, but as soon as the immediate pain had passed 

 away, appeared to have undergone no injury. It 

 attracted no further attention until it began to 

 loosen, and the crown came off some eighteen 



