286 ANIMAL BIOLOGY 



through the air so as to make the water evaporate more 

 rapidly and you will feel a sensation of coolness. The 

 more perspiration is evaporated at the surface the greater 

 the cooling effect; thus by means of the changes in the 

 circulation of the skin and the activity of its glands our 

 skin is able to act as a self-regulating mechanism, keeping 

 the temperature always at a certain point. 



In order that our skin can perform its functions properly, 

 especially the regulation of temperature, it must be kept 

 clean so that its pores are prevented from becoming clogged. 

 We not only acquire dirt from the outside, but we sweat 

 it out from within, and the waste matters in the form of 

 salts, and various impurities accumulate, some of them to 

 undergo decomposition to the distress of our associates 

 if not of ourselves. 



But bathing is desirable not only to get rid of dirt, but 

 as a tonic to the skin and incidentally to the whole body. 

 The cold dash or shower for a moderately robust person 

 tones up the blood vessels of the skin and renders him 

 much less liable to colds and various other forms of in- 

 fection. If after taking a cold bath a person does not re- 

 spond, after a vigorous rubbing, so as to feel an exhilarating 

 glow, he had better confine himself to warmer water. 



