EXCRETION AND THE EXCRETORY ORGANS 537 



Hygiene of the Skin. The sebaceous secretion, and the solid 

 residue left by evaporating sweat, constantly form a solid film 

 over the skin, which must tend to choke the mouths of the sweat- 

 glands (the so-called " pores" of the skin) and impede their ac- 

 tivity. Hence the value to health of keeping the skin clean: a 

 daily bath should be taken by every one. 



Bathing. The general subject of bathing may be considered 

 here. One object of it is that above mentioned to cleanse the 

 skin; but it is also useful to strengthen and invigorate the whole 

 frame. For strong healthy persons a cold bath is the best, except 

 in extremely severe weather, when the temperature of the water 

 should be raised to 15 C. (about 60 F.), at which it still feels 

 quite cold to the surface. The first effect of a cold bath is to con- 

 tract all the skin-vessels and make the surface pallid. This is 

 soon followed by a reaction, in which the skin becomes red and 

 congested, and a glow of warmth is felt in it. The proper time to 

 come out is while this reaction lasts, and after emersion it should 

 be promoted by a good rub. If the stay in the cold water be too 

 prolonged the state of reaction passes off, the skin becomes cold 

 and pale and the person feels chilly, uncomfortable, and depressed 

 all day. Then bathing is injurious instead of beneficial; it lowers 

 instead of stimulating the activities of the Body. How long a 

 stay in the cold water may be made with benefit depends greatly 

 on the individual: a vigorous man can bear and set up a healthy 

 reaction after much longer immersion than a feeble one; moreover, 

 being used to cold bathing renders a longer stay safe, and, of 

 course, the temperature of the water has a great influence: water 

 called "cold" may vary within very wide limits of temperature, 

 as indicated by the thermometer; and the colder it is the shorter 

 is the time which it is wise to remain in it. Persons who in the 

 comparatively warm water of Narragansett during the summer 

 months stay with benefit and pleasure in the sea, have to content 

 themselves with a single plunge on parts of the coast where the 

 water is colder. The nature of the water has some influence; the 

 salts contained in sea-water stimulate the skin-nerves and pro- 

 mote the afterglow. Many persons who cannot stand a simple 

 cold fresh-water bath take one with benefit when some salines are 

 previously dissolved in the water. The best for this purpose are 

 probably those sold in the shops under the name of "sea-salts." 



