CHAPTER XXII 



THE HEALTH OF THE SKIN 



When a barefoot boy takes a needle and thread and 

 sews stitches in the skin on the bottom of his foot, he 



does not intend to go 

 deeper than the out- 

 side layer, the epi- 

 dermis; yet if he pricks 

 himself, he knows at 

 once that he has gone 

 through the epidermis 

 and put his needle into 

 the inside layer, the 

 dermis. 



If no blood comes 

 when a man slices off 

 a bit of skin as he 

 shaves, we know he has 

 cut nothing but epider- 

 mis ; if blood does flow, 

 however, we know he 

 has cut the dermis too. 



The truth is that what we call skin is made up of two 



layers, the dermis, that holds nerves, sweat glands, and 



114 



TESTING THE EPIDERMIS 



