HANNOVER, ON DENTAL TISSUES. 171 



aware that any one has as yet absokitely seen endoplasts or 

 their remains in distinctly formed or forming enamel or 

 dentine. 



Mr. Tomes, in the excellent essay we have cited, endeavours 

 to prove that Nasmyth^s membrane is formed by the union 

 of the ends of the cells of the membrana adamantince , which 

 coalesce into a membrane ; and this view would undoubtedly 

 relieve one of much difficulty in understanding the formation 

 of the enamel, and would bring it nearly into the same 

 category as that of molluscan shell ; but until it can be 

 shown that Nasmyth's membrane is not continuous with the 

 membrana jjreformativa, and is not an alteration of it, we must 

 adhere to the view that the enamel is, like the dentine, formed 

 under the membrana prejormativa. Hitherto no one has 

 attacked this side of the argument, nor has the evidence 

 derived ffom the obvious continuity of the membrana pre- 

 formativa over the whole surface of the teeth in fishes and 

 Amphibia been in any way shaken. T. H. H. 



