French National Institute, 1S3 



FREKCH NATIONAL INSTITUTE. 

 [Continued from p. 90.] 



The researches of JVI. Cuyier upon the fossil grinders of 

 plephants haying led him to examine some fresh grinders, 

 and the opportunity he had within these few years of disr 

 secting two elephants, almost adult, having admitted of his 

 examining in detail the manner iri which the teeth of these 

 animals grow, he drew from these examples some conclu- 

 sions on dentition in general. We may consider the ana- 

 tomy of large animals as a kind of natural microscope, which 

 assists better in seeing the anatomy of others. 



M. Cuvier was led to confirm the doctrine of John Hunter, 

 at least so far as regards the substance called osseous. It has 

 no vessels, and is not formed by intus-susceptipn like true 

 bones, but a successive transudation of layers produced by 

 the pulpy nucleus of the tooth, and which ^re glued the one 

 over the other. The enamel is deposited above by the mem- 

 brane which envelops the young tooth, and is there fixed by 

 a kind of crystallization : lastly, a third substance, proper to 

 certain herbivorous animals, is deposited after the enamel, 

 but by the same membrane, which changes its nature at ^ 

 certain epoch. 



These two last points had also been observed upon smaller 

 teeth by K. Blake, an Irish anatomist. 



This thin substance ^ad been originally discovered by 

 M. Tenon, who named it cortical osseucp, but who regard* 

 it as formed by the ossification of the capsular membrane. 



This respectable anatomist has continued to communicate 

 to us his grand work upon teeth ] and this year he has given u» 

 adescription of those of the cachalot and crocodile. The teeth 

 pi the former have no enamel, but only the osseous cortex. 

 The one may be easily distinguished from the other, because 

 the enamel is much harder, and is entirely dissolved in the 

 acids, without leaving any gelatinous parenchypie. The 

 tusks of the elephant, and the grinders of the bear and of 

 the dugoug, have no other envelope. 



As M. Cuvier, in speaking of the teeth of elephants, had 

 felated several observations recently made, boih by himself 

 and Messrs. £verard, Home, Corse, and R. Blake, natu- 



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