ixan of tbc C^cttfj. 



By R. SHINGLETON SMITH, M.D., F.R.C.P., B.Sc. 



[Ahslrad.] 



A TOOTH was sliown to be a modification of the liorny 

 epitliolium of the skin intimately associated with a 

 bony development from within : mammalian teeth being not 

 simply horny, nor bony alone, but made up of several struc- 

 tures variously arranged in different animals. The cha- 

 racters of a typical simple tooth were described, and its 

 transfoi-mations traced from its earliest period— the conical 

 projection in the mucous membrane of the gum, which, 

 being transformed into a layer of calciiied bony dentine and 

 covered with the epithelial enamel, forms the adult tooth. 

 The process of development of the milk and the permanent 

 teeth was given in outline, and the dates at which in in- 

 fantile life the germs of the permanent teeth are being 

 formed wore indicated. 



It was pointed out that the function of the teeth is 

 mainly a mechanical one, that of mastication, in association 

 with the chemical action of the salivary glands ; but that 

 nevertheless the structure of dentine gives indications of 

 vital activity, nutritive changes being found therein, where- 



