202 BIOLOGY AND HUMAN LIFE 



ture, but it should never be taken when the body is exposed to 

 cold air. The best time is immediately upon rising, or after 

 vigorous work or play that has produced free sweating. Yet 

 there are many people who cannot tolerate a cold bath because 

 of the after-effects of the shock, and it cannot be recommended 

 to everybody. Each one must find out for himself whether he 

 can benefit from it. All of us can stand a splash of cold water 

 after a warm bath, or in the morning, over the chest and back ; 

 and probably most of us can learn to stand the cold bath, either 

 by systematically lowering the temperature of the bath day by 

 day or by increasing the surface to which we apply cold water 

 with a sponge. In any case the cold bath should be followed by 

 a brisk rub with a coarse towel. 



The slow, continuous perspiration, of which we are not aware, 

 leaves deposits of wastes in the tubules of the sweat glands. 

 INIore rapid perspiration w^ashes these wastes out. Exercise 

 that results in sweating cleans out the pores. It also increases 

 the circulation of blood in the skin and so helps to clear the 

 complexion and maintain the tone of the skin muscles. One of 

 the great advantages of athletics from a health point of view 

 is the fact that the exercise is commonly followed by a shower 

 bath and that it makes us take a certain satisfaction in the good 

 condition of the body. Bathing itself, aside from making for 

 cleanliness, has also the additional virtue that it gives us a satis- 

 fying habit of feeling that the body is in good condition. 



We have a special problem to keep the scalp and the hair 

 clean and to keep up vigorous circulation in the skin of the 

 scalp. A shampoo of pure soap or soft soap two or three times 

 a month, with a thorough rubbing of the scalp and vigorous 

 brushing every day, will take care of the cleanliness. A stiff 

 brushing that reaches to the scalp and energetic work with the 

 finger tips will be needed to insure circulation in the scalp. 

 General exercise that induces sweating will serve the skin on 

 the head just as it does the skin on other parts of the body. 



168. Clothing. The clothes that we wear are related to our 

 health in two different ways. They influence the work and the 



