392 



THE ORGANS 



vertical plane extending from the periosteum to the nail. Papillae 

 are not present, but in their place are minute longitudinal ridges, 

 which begin at the matrix and, increasing in height as they pass for- 



n 







''^Mmji.s,:,, 



Fig. 276. — Transverse Section of Nail and Nail Bed. (Rannie.) ?f, Nail; a, epidermis; 

 p, nail wall, to inner side of which is the nail groove; /, folds of derma; d, nail bed. 



ward, terminate abruptly at the end of the nail bed, beyond which are 

 the usual papillae of the derma. 



The nail itself consists of two parts^ — an outer harder part or 



.,-'tj''~i ^1» ' &. -i ^ 









}. ,f Q lit 



■J 



Si- '^.iDysf, 6 





Fig. 277. — Vertical Transverse Section through Nail Body. X280. (Szymonowicz. 

 a, Nail; h, stratum germinativum; c, ridge of nail bed; d, derma; e, blood-vessel.) 



true nail, and an under softer part. The outer portion is hard and 

 horny, is developed from the stratum lucidum, and consists of several 

 layers of clear, flat, nucleated cells. These layers overlap in such a 



1 Another division of nail and nail bed considers the nail as composed of the hard 

 part only, the soft stratum germinativum being considered a part of the nail bed. 



