40 MICROSCOPIC ANATOMY OF THE TEETH 



two enamel organs or the subdivision of one. If considered 

 to represent the latter, this photograph (p. 369, To-mes's- 

 Dental Anatomy, 7th ed.) shows Bolk's enamel septum ami 

 the enamel groove or navel in the external epithelium. 



In a preparation of the author's of the enamel germ of 

 Macropus the enamel septum is very evident, as shown in figs. 

 11 and 12. The stellate reticulum is seen to be divided into 

 two parts, and the cells in the septum are not fully differen- 

 tiated. Under higher magnification (fig. 12) the junction of 



FIG. 12. Under higher magnification, showing blending of cells of the 

 enamel septum with those of the stratum intermedium. ( x 350.) 



the cells of the septum with those of the stratum inter- 

 medium is well seen. In this preparation, however, the 

 septum cannot be traced to its junction with the external 

 epithelium, and the groove on the surface of the latter is 

 not visible. It does not appear that in this case the line of 

 cells can be looked upon as indicating the fusion of two 

 enamel organs, but actually represents the subdivision of 

 one, and tends to lend confirmation to Bolk's description, 

 As he finds these structures in the enamel organ of the 

 primates, Bolk considers that they indicate that each 

 primate tooth arises from the fusion of two separate germs ; 



