240 STUDIES IN PHYSIOLOGY 



2. HYGIENE OF THE SKIN 



Importance of Bathing. The sebaceous and perspiratory 

 glands are constantly pouring their secretions in greater 

 or less quantity upon the skin. As the water evaporates, 

 the oil and the solid ingredients of the sweat are left behind. 

 Unless these are removed, they tend to clog the openings 

 of the ducts from the glands and so interfere with the work 

 of the skin. A considerable amount of these substances is 

 doubtless worn away, together with the scales of the outer 

 skin, by friction against the clothing. But if the skin is to 

 carry on its functions to the best advantage, frequent baths 

 must be taken. 



Kinds of Baths. The oily secretions and much of the 

 accumulated dirt on exposed surfaces of the skin can be 

 removed only by the use of warm water and soap ; hence 

 these should be employed upon the face and hands two or 

 three times a day and at least once or twice a week upon 

 the whole body. Warm baths should be employed, how- 

 ever, for their cleansing effect only, since they are usually 

 followed by a feeling of lassitude. One is much more likely 

 to catch cold, too, after exposure to warm water, as it opens 

 the pores of the skin, causes the arteries near the surface 

 to dilate, and thus increases the amount of perspiration. 

 Unless the warm bath is taken just before going to bed, 

 it should be followed by a quick application of cold 

 water. 



Cold baths, on the other hand, if taken under proper con- 

 ditions, have an exhilarating effect. The best time for such 

 a bath is immediately on rising in the morning. Until one 

 becomes accustomed to the cold temperature, the water may 

 be applied with a sponge. The body should then be rubbed 

 vigorously with a coarse towel. In our study of the circu- 

 lation we referred to the effect of heat and cold upon the 

 arteries. After their first quick contraction caused by the 

 contact of the cold water with the skin, the blood vessels 



