22 HUMAN BIOLOGY 



as a whole may be cooler, but we feel wanner when 

 there is more blood in the skin because of the effect of 

 the warm blood upon the nerves of temperature. There 

 are no nerves for perceiving temperature except in the 

 skin and mucous membrane, and the body has practically 

 no sensation of heat or cold except from the skin or 

 mucous membrane. That alcoholic drinks make the skin 

 red is commonly noticed. Often the skin is flushed by 

 one drink ; the bloodshot eyes and purple nose of the 

 toper are the results of habitual use. Can you explain 

 why alcohol brings a. deceptive feeling of warmth? Why 

 does alcohol increase the danger of freezing during ex- 

 posure in very cold weather ? During the chill which pre- 

 cedes a fever, the body (except the skin) is really warmer 

 than usual. 



Exercise will relieve internal congestion and send the 

 blood to the skin better than alcohol. This is the effect 

 sought by sedentary people who use it to replace exercise. 

 The long and sad experience of the race with alcohol 

 proves that the attempt to adapt the body to its use should 

 be given up. 



Thought Questions. The Functions of the Skin. — 1. State a fact 

 which shows that the skin is a protection ; gives off offensive sub- 

 stances ; regulates the temperature. 2. What is lacking in the skin 

 when it cracks or chaps? Why does this occur more often in cold 

 weather? When the hands are bathed with great frequency? 



Effects of Indoor and Outdoor Life. — Those who live much out of 

 doors, exposed to sunlight and pure, cold air. are robust and hardy ; 

 while those whose occupations keep them constantly indoors, especially 

 if no physical labor is necessary, show by their pale skins, their fat and 

 flabby, or their thin and emaciated bodies, the weakening effect of such 

 a life. We are descended from ancestors who lived in the open air, and 

 it is impossible for a human being to live much indoors without de- 

 generation of the body and shortening of life. 



A Well-trained Skin. — We hear a great deal about training the 

 muscles, the brain, the eye, the hand ; yet we may fail to realize that 



