CHAPTER VI 



THE SKIN AS AN ORGAN OF SENSATION TOUCH 



105. Functions of the Skin. The whole body is covered 

 with a flexible, elastic membrane of complex structure, 

 which serves several different purposes. It envelops 

 and protects the inner, soft parts, and especially the ends 

 of the nerves. It is one of the three principal channels 

 by which the waste products of the body are removed 

 that is, it is an organ of excretion. It regulates the 

 temperature of the body by controlling the loss of heat 

 through general radiation and evaporation, as well a by 

 the direct action of the sweat glands in excretion. A 

 small amount of respiration, or exchange of gases, also 

 goes on in the skin, and it contributes by its general char- 

 acteristics and its various modifications to the ornamen- 

 tation of the body. 



106. Structure of the Skin. The present chapter has to 

 do with the skin as one of the organs by means of which 

 the nervous system is brought into direct communication 

 with the external world, that is, as the seat of the sense 

 of touch and of certain other allied nervous impressions. 



Two distinct layers are found in the skin, called the 

 epidermis, or cuticle, and the dermis, corium, or true skin 

 (Fig. 49). The epidermis is composed of epithelial tis- 

 sue, or epithelium, and its cells lie in layers one above 

 another, the outer or horny layer of cells being flat, 



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