434 APPENDIX. 



Every integument and every mticous membrane may, in fact, be 

 distinguished into three portions ; a central plane of indifferent 

 tissue, from which growth and metamorphosis take place ex- 

 ternally, to constitute the representative of epidermis or 

 epithelium, to which we propose to give the name of ecderon; 

 while internally, growth and metamorphosis take place from 

 the central plane, so as to constitute the representative of the 

 derm or 9 mucosa," which we have termed the enderon. 



Now the dental pulp is a process of the whole integument, 

 and its outer surface, although bounded by a " basement mem- 

 brane," truly represents the deepest layer of the ecderon of 

 ordinary integument, while its inner substance belongs to the 

 enderon. Although, therefore, the dentine is not a calcified 

 cellular epidermis, it is a calcined ecderon, and grows in the 

 same manner as an ecderon would do. The cement follows 

 the dentine, and whatever the view we take of the development 

 of the enamel, it also belongs to the ecderon. Although, 

 therefore, the teeth are not, in the ordinary sense, epidermic 

 structures, they are homologous with the ecderon, and not 

 with the true derma or enderon of the mucous membrane. 



END. 







J. K. ADLARD, PRINTKR, BARTHOLOMKW CI.OSK. 



