^ Memoir upon living arid fossil Elephants. 



pulpy nucleus at the period when it secreted the altered por- 

 tion ; and what has been called exostosis is always inside, 

 and never outside. It is the efToct of a secretion for the 

 moment, too abundant at a certain point. 



Specimens of diseased ivory have been often given by ex- 

 hibiting the canine teeth of the morse {trichecus rosmanis); 

 the texture of which is naturally grained. Daubenton him- 

 self has fallen into this error. 



The diseases of the teeth are nearly in the same case as 

 those of the ivory. 



What has been called caries, an almost necessary conse- 

 quence of the removal of the enamel, is the decomposition 

 wihlch the internal substance would undergo, when it would 

 eveji be no longer adherent to the body if it remained ex- 

 posed to the heat of the mouth, and the action of the saliva 

 and various food ; but it has no reference whatever to the 

 caries of the bones. 



The tendency to caries which the teeth of several people 

 tvince, proceeds from their substance not being of a good 

 composition, and may be ascribed to the bad state of the 

 pulpy nucleus when it transuded them. 



It is the same with the spots and the more tender layers 

 wc observe in the thickness of some teeth. All are the ef- 

 fects of momentary indispositions of the pulpy nucleus. 



Pains and inflammations exist in the pulpy nucleus, and 

 not in the hard part of the tooth. It is the pulpy nucleus 

 which is sensible to the shocks and the temperature of bo- 

 dies passing through the envelop which the hard part form* 

 around it. 



It may be perhaps surprising to some that so thick and 

 hard an envelop does not blunt all sensation ; but the pulp 

 of the nucleus of the teeth is, next to the retina and the 

 pulp of the labyrinth of the ear, the most sensible part of 

 the animal frame. Fishes, which have their labyrinth in- 

 closed in the cranium, without any box or tympanum, and 

 without small hones ; in a word, without any communica-- 

 tion opening externally, hear sounds in consequence of vi- 

 brations communicated to the cranium. The teeth, how- 

 ever. 



