THE EXCRETORY SYSTEM 



195 



root presents a bulbous enlargement at its extremity; the 

 shaft consists of a central part or medulla. 



Hairs are found on almost every part of the human 

 body, but are most numerous on the scalp, and, in the 



FIG. loo. Skin and longitudinal section of hair: a, Epidermis; b, 

 corium ; c, sebaceous gland ; d, fibrous root-sheath ; ?, glassy membrane ; 

 i outer root-sheath; g, inner root-sheath; h, expanded bulbous end of 

 air; i, papilla of hair; j, arrector pili ; k, adipose tissue (Leroy). 



if; 



male, on the face, where, in the beard, they are thick and 

 coarse in character. At puberty hair appears on the pubis 

 and in the armpits. 



The nails are flattened, elastic structures of a horny 

 texture, situated upon the dorsal surface of the terminal 



