ENAMEL 61 



enamel prisms with such cells it will be seen that this arched 

 or concavo-convex shape of the prism renders it necessary 

 to conclude that in longitudinal section it should show 

 a convex margin, and a single, double, or compound groove 

 on the reverse side (figs. 15 and 24). As in the epithelium 



FIG. 23. Drawing to show the arrangement of the 

 epithelial cells in a pavement epithelium. 



the interval between the cells is crossed by the prickle 

 processes, so in enamel the prisms are connected by bridges 

 which traverse the interprismatic substance which cements 

 together the interlocking prisms. 



FIG. 24. Human enamel. Transverse prisms, (x 1,500.) 



Such an arrangement would necessarily give a very 

 perfect adaptation and tend greatly to increase the resistance 

 of the enamel to any disrupting force. These observations 

 have received very little attention and are not even referred 

 to in recent text-books. They were considered by Walkhoff 

 to be false appearances and not to be evidence of any 

 real structure in the enamel. A careful examination of 

 suitably prepared sections, however, and the evidence 



