THE SKIN AND THE KIDNEYS 



195 



have to a worm. This oily secretion, which might well be 

 called nature's hair oil, is perfectly fluid in a healthy skin, 

 and at the temperature of the body, 



263. The Sweat Glands. The sweat 

 glands consist of very fine tubes, about 

 one quarter of an inch long, coiled into 



knots. From 

 | each knot a 



canal, called a 



sweat duct, rises 



up through the 



dermis and, 



piercing the epi- 



dermis in cork- 



screw fashion, 



opens on the surface of the skin. 

 The openings, or small pits, of these 



* f 



FIG. 122. Concave or 

 Adherent Surface of 

 Nail. 



A, border of the root ; B, 

 whitish portion of semi- 

 lunar shape ; C, body of 

 nail. The continuous 

 line around border rep- 

 resents the free edge. 



FIG. 1 23. Nail in 

 Position. 



A, section of cutaneous fold 



turned back to show sweat glands are set in rows, as may 



root of nail; B cutane- be seen by a common magnifying 



J J & 



glass, 



ous fold covering root 



of nail; C, semilunar 



whitish portion; D, body cially on 



of nail. J 



the palms 



of the hands between the ridges 

 of the skin. On the sole of the 



foot and the palm of the hand FIG. 124. Longitudinal Section 



they are very numerous, there of a Finger Nail 



, , , , f A, last bone of finger : B, true skin 



being some three thousand of on the dorsal surface of finger . 



them to the square inch ; while 



on the cheeks there are only 



about five hundred and fifty in 



the same space, and about twelve hundred to the square 



inch on the forehead. At a rough estimate, there are more 



C, outer skin; D, true skin; E, 

 bed of nail; F, superficial layer 

 of nail ; //, true skin of pulp of 

 finger. 



