110 MICROSCOPIC ANATOMY OF THE TEETH 



In a longitudinal section (fig. 60) there is quite a different 

 appearance. The prisms are arranged at an angle of 60 

 to the dentine surface and are not seen to decussate, but 



e 



FIG. 60. Enamel of Beaver (Castor). Longitudinal section, d. Dentine 

 e. enamel, inner layer ; e'. outer layer. ( x250.) 



A B 



FIG. 61. A. Diagram to show the arrangement of the prisms of the 



Beaver as viewed in a transverse section. E. enamel surface ; D. dentine 



surface. 



B. As viewed in a longitudinal section. 



are parallel to one another, the intercrossing laminae being 

 viewed on edge. At a little less than half-way across the 

 enamel they abruptly change their direction to one at an 

 angle of 30 to the dentine surface. 



The structure may be perhaps better explained by the accompanying 

 diagram, fig. 61 A and B, as it is difficult to clearly comprehend the 



