244 ADVANCED PHYSIOLOGY 



fusely, and their skin has little power of regulating tempera- 

 ture. Such animals must depend largely upon respiration 

 to rid themselves of surplus heat. This explains the panting 

 of dogs, and their rapid breathing in hot weather or when 

 exercising rapidly. 



CARE OF THE SKIN 



To insure the healthful functioning of the skin, the pores 

 of the sweat glands must be kept free and open. The fat 

 glands connected with the hair follicles are constantly exuding 

 a certain amount of oil, and the sweat glands give out much 

 water, salts and other substances. The water will readily 

 evaporate, but the solid material will remain on the skin, 

 tend to clog the pores, check the ready action of the glands 

 and cause an offensive odor. Evidently the normal action 

 of the skin demands that this material be removed. To keep 

 the pores open, habitual bathing and washing of the skin is 

 a necessity. The frequency of the bath, however, is a matter 

 in regard to which no rule can be given. A daily bath is 

 certainly desirable, though doubtless not necessary to health. 



It is a mistake to suppose that cleanliness is the primary 

 benefit to be derived from bathing, although it is an im- 

 portant one. The principal effect of the bath is in stimu- j 

 lating the skin, and increasing its activity. The skin is a 

 delicate organ, in which more blood is exposed to the air than 

 in any other organ in the body. A large part of one's com- t 

 munications with the outer world are received through it. 



Cold Baths. The first effect of a cold bath, whether it be a 

 plunge in cold water, a shower bath or merely a sponge bath, ! 

 is to stimulate the temperature nerves of the skin, producing a 

 decided sensation of cold. This acts through the brain and 

 causes (1) a contraction of the blood vessels in the skin; for 

 a short time the skin becomes white and cold, due to this 

 contraction. But this is presently followed by (2) a reaction; 

 almost immediately the brain withdraws its contracting in- 



