152 A MANUAL OF DENTAL ANATOMY. 



spending in size and being continuous with the enamel cells 

 whence they were shed out. 



Professor Huxley's reason for doubting the direct con- 

 version of the enamel cells into enamel was that a membrane 

 could be raised from the surface of growing enamel, at any 

 period of its development, by the use of acid reagents, this 

 membrane necessarily intervening between the formed 

 enamel and the enamel cells ; hence he denied that the 

 enamel organ contributed in any way directly, though it 

 might indirectly, to the development of the enamel. 



To the nature of this " membrane " I shall have again to 

 refer, so that for the present it will suffice to say that the 

 structure in question cannot be demonstrated, and in fact 

 has probably no existence, prior to the use of the reagent. 



The cells of the internal epithelium of the enamel organ 

 or enamel cells have been already in some measure de- 

 scribed : they are elongated cells, forming a very regular 

 columnar epithelium, and are hence rendered hexagonal by 

 mutual apposition ; they vary in their length and diameter 

 in different animals. 



To secure uniformity of nomenclature, the name adaman- 

 toblast has recently been proposed for them, as being better 

 comparable with the term odontoblast and osteoblast. 



Although they are connected with the cells of the stratum 

 intermedium by a process at their base, they often adhere 

 more strongly to the enamel, when once this has begun to 

 be formed, than to the rest of the enamel organ, so that 

 when a dental sac is opened the enamel cells are most easily 

 obtained by scraping the surface of the enamel. The cells 

 thus torn away often have tapering processes at the ends 

 directed towards the enamel, which were first described by 

 my father, and go by the name of " Tomes' processes." The 

 cells are also slightly enlarged at these extremities, especially 

 if they have been immersed in glycerine or any such fluid 

 which causes their shrinkage, for this end of the cell having 



