340 MICROSCOPIC ANATOMY OF THE TEETH 



preparations are elongated crescentic or thread-like bodies, 

 which appear to be degenerated nuclei as described by 

 Romer in altered epithelial cells. 



In many parts of these preparations cells are seen which 

 are quite different in appearance. They are elongated, with 

 nuclei at their distal ends, and appear to be attached to the 

 clear membrane by broad expansions ; they have, in fact, 

 a strong resemblance to altered and shrivelled ameloblasts 

 (figs. 228 and 229). Owing to the method of preparation this 



FIG. 228. Elongated cells in Xasmyth's membrane ( x 250.) 



elongation of the cells cannot be due to stretching, and when 

 these specimens are compared with those of Nasmyth's mem- 

 brane seen in longitudinal section (figs. 230, 231, and 232), it 

 seems impossible to avoid the conclusion that these are cells 

 of the inner epithelium of 'the enamel organ which have 

 undergone keratinization. 



Passing to an examination of these longitudinal sections, 

 it is seen that these appear to shed a new light on the nature 

 and extent of the cells included in the membrane. 



There have been considerable differences of opinion with 

 regard to the persistence of the external epithelium in the 

 later stages of calcification, some authors, as Professor 

 Underwood (11), stating that it becomes blended with the 



