CH. XXXVIII. 1 



THE HAIRS. 



573 



lies in a depression called the bed of the nail, the posterior part 

 of which is overlapped by epidermis, and called the nail-groove. 

 The dermis beneath is beset with longitudinal ridges instead of 

 papillae ; these are very vascular ; but in the lunula, the crescent 

 at the base of the nail, there are papillae, and this part is not so 

 vascular. 



Fig. 442. Surface of a white hair, magnified 160 diameters. The wavy lines rnaik the 

 uppo-r or free edges of the cortical scales. R, separated scales, magnified 350 diameters. 

 (Kolliker.) 



The Hairs are epidermal growths, contained in pits called hair 



follicles. The juirt within the follicle is called the root of the hair. 



The main substance of the hair is composed of pigmented 



Fig. 443. Longitudinal nection of a hair follicle, a and b, external root-sheath ; c, internal 

 root-aheath ; J, fibrous layer of the hair ; e, medulla ; /, hair papilla ; y, blood-YMMli 

 of the hair-papilla ; A, dermic coat. (Cadiat.) 



horny fibrous material, in reality long fibrillated cells. It is 

 covered by a layer of scales imbricated upwards (hair cuticle). 

 In many hairs the centre is occupied by a medulla, fonned of 

 rounded cells containing eleidin granules. Minute air-bubbles 



