HYGIENE OF EXCRETION 207 



For those who can stand it a daily cold bath is refreshing 

 and at the same time an excellent training for the skin in 

 adjusting itself to changes in temperature. The cold bath 

 should never be taken when the body is exposed to cold, 

 however. The best time is immediately upon rising, or 

 immediately after physical work or exercise that has produced 

 copious sweating. But since there are many people who 

 cannot tolerate the cold bath, because of the after-effects of 

 the shock, it is not to be generally recommended. 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 gradually learn to stand the cold bath, either by 

 systematically lowering the temperature of the water used, 

 day by day, or by increasing the surface to which cold water 

 is applied with a sponge. In any case the cold bath should 

 be followed by a brisk rub with a rough towel. 



It is hardly necessary to remind anyone that bathing will not main- 

 tain cleanliness if the underclothing is not changed with sufficient 

 frequency. 



240. Exercise. The value of exercise for the muscles, for 

 the heart, for the breathing, for the digestion, and for the 

 work of the bowels has already been mentioned. The value 

 of exercise for the skin and the excretion generally is worth 

 noting. The slow, continuous perspiration, of which we are 

 not aware, leaves deposits of wastes in the tubules of the 

 sweat glands. More rapid perspiration washes these wastes 

 out. Exercise that results in sweating cleans out the pores. 

 In so far as exercise accelerates the flow of the blood, it 

 contributes also to the more rapid removal of wastes through 

 the kidneys. 



