EXCRETORY SYSTEM 355 



heat produced and the amount lost is brought about 

 and regulated through the action of the nervous 

 system. 



Clothing. In cold climates clothing helps to keep 

 the body warm by checking radiation and by keeping 

 off currents of air which would carry heat away. For 

 this purpose our clothing should be made of materials 

 which are poor conductors of heat, such as silk and 

 wool. Linen and cotton, on the other hand, are good 

 conductors of heat. Under what conditions should they 

 be worn? 



Care of skin. The various excretions from the skin 

 are constantly collecting on its surface. These together 

 with the dirt from the air around us must be removed, 

 otherwise they would soon clog the ducts from the 

 pores and so interfere with the work of the skin. 



Warm baths are. necessary for cleansing. To aid in 

 removing the oily secretions from the skin a good soap 

 should be used. In addition to cleansing, the warm 

 bath opens the pores, causes the blood vessels in the 

 skin to dilate, and this increases the amount of per- 

 spiration. Warm baths should be taken before going 

 to bed. 



Cold baths should be taken as a stimulus. The best 

 time for such a bath is immediately on rising in the 

 morning. It should last "but a few minutes and should 

 be followed by vigorous rubbing. The cold bath is 

 not advisable for all persons ; for some it is beneficial, 

 for others it is too severe and should not be taken. 



