114 MICROSCOPIC ANATOMY OF THE TEETH 



processes appear to pass between the prisms where viewed in 

 transverse section and to project from them in places where 

 viewed in longitudinal section. In fig. 65, at a, a single 

 transversely-cut prism is seen with a narrow process on 

 either side of it which certainly suggests the presence of 

 some intervening substance and not a serration of the prism. 

 The markedly fibrous nature of rat's enamel was drawn 

 attention to by Leon Williams in his paper on enamel (21), 

 where he says, ' Enamel from the teeth of rats and mice 



FIG. 64. Enamel of Rat. Interdigitation of transverse and longitudinal 

 prisms and interprismatic substance. ( x 700. ) 



shows a more marked fibrous character than any other 

 that I have examined, and the most striking feature of 

 arrangement of the fibres is the interlacing or weaving 

 together of those running in different directions like warp 

 and woof in a web ' . He compares the appearance of the 

 broken edge of the enamel to that of a torn fabric. This 

 fibrous condition of the enamel is shown in fig. 67 from 

 a ground section accidentally torn in the middle, and it is 

 also very noticeable in the outer layer of enamel close to 

 the surface, where an interlacement of fine fibres is seen 

 mostly running in a direction parallel to the surface (fig. 66). 

 Leporidae. In the Hares and Rabbits (Leporidae) there is no division 

 of the enamel into an outer and an inner layer, and the 

 prisms are not arranged in alternating lamellae. Von Ebner 



