40 TOOTH-GEEMS. 



Again, in the Society's TraRsactmis for 1876 (p. 265), 

 Prof. Tomes says: 



''1. It is desirable to abandon the terms ^papillary,' 

 * follicular,' and 'eruptive' stages, inasmuch as they 

 are hypothetical and arbitrary, and correspond to no 

 serial conditions verified by observation. 



''2. In all animals a tooth-germ consists primarily 

 of two structures, and only two — the dentine-germ 

 and the enamel-germ*. The simplest tooth-germ never 

 comprises anything more. When a capsnle is devel- 

 oped, it is derived partly from a secondary upgrowth 

 of the tissue at the base of the dentine germ, and partly 

 from an accidental condensation of the surrounding 

 connective tissue. 



"3. The existence of an enamel-organ is quite uni- 

 versal, and is in no way dependent on the presence or 

 absence of enamel on the completed tooth, although 

 the degree to which it is developed has distinct relation 

 to the thickness of the future enamel. 



"4. So far as my researches go, a stellate reticulum, 

 constituting a large bulk of the enamel-organ, is a 

 structure confined to the mammalia. (It is absent in 

 the armadillo, and I should infer from Mr. Turner's 

 description, in the narwhal also). 



"5. x\s laid down by Profs. Huxley and Kolliker, 

 the dentine-papilla is beyond all question a dermal 

 structure, the enamel-organ an epithelial or epidermic 

 structure. As I believe it can be shown that the enamel 

 is formed by an actual conversion of the cells of the 

 enamel-organ, this makes the dentine a dermal and 

 the enamel an epidermic structure. 



"6. In teleosts the new enamel-germs are formed 

 directly from tlie oral epithelium. They are new for- 

 mations, and arise quite independently of any portion 



