CHAPTER XXXI 

 THE SKIN 



The most obvious function of our skin is that of protect- 

 ing the organs which it covers, but it serves also as an 

 organ of excretion, a medium for the regulation of bodily 

 temperature, and a sensory surface adapted to receive 

 many kinds of impressions from the outer world. A few 

 facts about the structure of the skin will help us to under- 

 stand how it performs its functions. 



The skin is composed of two layers, a deeper one the 

 corium, and an outer cuticle or epidermis, which consists of 

 epithelial cells without blood vessels or nerves. The outer 

 cells of the cuticle are dead and as they are shed or rubbed 

 off, they are continually replaced by cells from beneath. 

 When a blister is formed the cuticle is lifted away from the 

 corium by serum which exudes between these two layers. 

 The corium is a relatively thick layer of connective tissue 

 containing muscle fibers, blood vessels, glands, the end 

 organs of nerves, and various other structures. The 

 deeper part of the cuticle contains brownish pigment which 

 in colored races is especially abundant and which in our- 

 selves is increased when we become freckled or tanned. 



Among the most characteristic structures of the skin 

 are the sweat glands which are coiled tubes whose ducts 

 open through fine pores at the surface of the cuticle. 

 With a good hand lens these openings may be seen in 

 the palm of the hand. As many as 2,000,000 of them have 

 been estimated to occur over the entire body. Sebaceous 

 or oil glands are present wherever hair occurs which is 



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