THE NAILS. 



271 



at the bottom of a depression, formed by a pitting-in of the 



dermis. The depression is known as the hair follicle. The 



part of the hair buried in the 



follicle is called its root; this 



is succeeded by a stem, which 



(in uncut hairs) tapers off to a 



point. Each hair is made up 



of a number of epidermic cells, 



arranged together so as to form 



a fibre. 



Nails. A nail is a part of 

 the epidermis, with its horny 

 stratum greatly developed. The 

 back part of the nail fits into 

 a furrow of the dermis, and is 

 called its root. The visible part 

 consists of a body, attached to 

 the dermis beneath (which forms 

 the bed of the nail), and of a 

 free edge. Near the root is a 

 little area, whiter than the rest 

 of the nail, called the lunula. 

 The whiteness is due in part to 

 the nail being really more 

 opaque there, and partly to the 

 fact that its bed, which seen 

 through the nail causes its pink 

 color, is in this region less vas- 

 cular. 



The portion of the corium on which the nail is formed 



What is a hair follicle? What is the root of a hair? The stem? 

 Of what is a hair composed? 



What is a nail? Of what parts does it consist? What is the 

 lunula? Why is it paler in color than the rest of the nail? 



FIG. 77. The root of a hair iro 

 bedded in its follicle, o, stem of 

 hair cut short; o, 6, root of hair; 

 c, swollen part of root which fits 

 on z, the dermic papilla at the 

 bottom of the hair follicle; n, m, Z, 

 layer of skin which turn in to line 

 arid form the follicle; fc. k, mouths 

 of ducts of sebaceous glands. 



