100 ENAMEL OF THE TEETH. 



Purkinje and Raschkow regarded each fibre of the enamel- 

 membrane as an excretory organ, a little gland which secreted 

 the enamel-fibre corresponding to it. With our altered views of 

 the growth of unorganized l tissues, however, this explanation, 

 previously so plausible, loses much of its probability. Various 

 other explanations might be offered in place of it, but I have 

 not made sufficient observations to enable me to decide upon 

 the correct one. Firstly, one might suppose the organic basis 

 of the enamel-prisms to be cells, which are formed, and continue 

 to grow independently upon the dental substance, having no 

 other connexion with the prisms of the enamel-membrane than 

 that the latter furnishes their cytoblastema. This explanation, 

 however, would compel us to regard the remarkable accordance 

 which exists between the prisms of the enamel-membrane and 

 those of the enamel as an accidental circumstance. But we 

 should be obliged to adopt such a view, if it could be proved 

 that another peculiar substance intervened between the enamel- 

 membrane and the enamel, and I have several times observed 

 such an one on the molar teeth of swine. It is very soft and 

 full of vesicles, having the appearance of a slag. I think 

 Purkinje mentions it also, but I cannot find the precise passage 

 at this moment. It lay between the enamel-membrane and 

 the tooth, but I am not certain whether it was also present 

 at those points where the formation of the enamel had already 

 commenced, and whether, therefore, it actually interrupted the 

 continuity of the enamel-membrane with the formed enamel. 

 We might suppose, as a second explanation, that the enamel- 

 prisms are uninterrupted continuations of the prisms of the 

 enamel-membrane, which become filled towards one end with 

 calcareous salts. This is a very improbable explanation, and 

 the connexion between the two structures is of too loose a 

 nature to warrant its adoption. A third, and as I am at pre- 

 sent disposed to think the most probable, explanation is, that 

 the prismatic cells of the enamel-membrane separate from it, 

 and coalesce with the enamel already formed, while at the same 

 time their cavities either become filled with calcareous salts, 

 or they become ossified throughout their entire thickness, their 

 cavity being previously filled with an organic substance. This 

 explanation makes the formation of the enamel accord with 



1 [The author appears to use this word- as synonymous for " non-vascular." — Trans.] 





