THE SKIN AND THE KIDNEYS 



grow again. If we destroy this papilla, the hair never 

 grows again. 1 



The hair follicles are well supplied with nerves, hence it 

 hurts to have the hair pulled. 



258. How the Hairs grow. Hairs grow from cells 

 pressed together lengthwise, so that they are drawn out 

 into fibers instead of being flattened into scales. Hence 

 they grow only in length. On the outer surface the cells 

 form a sort of bark, 



overlapping each ^^^ 

 other something like 

 the shingles on a roof. 

 The coloring mat- 

 ter is contained in 

 the cells. It is this 

 pigment which gives 

 the great variety in 

 color. The hair usu- 

 ally becomes gray or 

 white as old age 

 comes on. The pigment is absent and the cells are filled 

 with air bubbles. 



259. Muscles that control the Hairs. The hairs, or 

 rather the parts of the skin close to them, are provided 

 with tiny muscles. They run from the bottom of each 

 hair follicle in a slanting direction, and end in the outer 

 part of the true skin. When they contract they cause the 



1 It is useless, or worse than useless, to try to rid one's self of unsightly 

 hairs or hair moles on the face. If we pull them out with tweezers, or cut 

 or shave them off, they are sure to grow again, coarser and more unsightly 

 than before. Remedies advertised to remove superfluous hairs are usually 

 worthless or dangerous. The hair papillae must be destroyed to stop the 

 growth of hair, and this is no simple matter. 



FIG. 118. BLACKBOARD SKETCH. 



Surface of Palm of the Hand, showing Open- 

 ings of Sweat Glands and Grooves between 

 Papillae of the Skin. 



Magnified 4 diameters. 



In the smaller figure the same epidermal surface is 

 shown as seen with the naked eye. 



