IN HYGIENIC PHYSIOLOGY. 153 



12. Why does the hair of domestic animals become 

 roughened in ivinter ? 



(See Question 2.) 



It is a wise provision of Nature, since more air a non-con- 

 ductor of heat is retained by the hair, and thus the rough 

 winter-coat of an animal is warmer than its smooth summer- 

 coat. 



13. Why do fotvls spread their feathers before they 



perch for the night ? 



(See Question 12.) 



This is the same wise provision of Nature to protect the 

 fowl against the chilliness of the night. More air is confined 

 by the roughened feathers, and thus the internal heat of the 

 bird is prevented from radiating. 



14. Hoiv can an extensive burn cause death by conges- 

 tion of the lungs ? 



(See Physiology, p. 63.) 



The insensible perspiration is stopped upon the burned sur- 

 face, and the excretions are sent to the lungs, which are over- 

 worked and overloaded by the excess. 



15. Why do ive perspire so profusely after drinking cold 

 water ? 



The vital organs being chilled for an instant, the blood is 

 sent to the surface, a reaction is produced, the skin acts more 

 vigorously as an excretory organ, and the insensible perspira- 

 tion is thrown off more rapidly. 



16. What are the best means of preventing skin dis- 

 eases, colds, and rheumatism ? 



The skin should be kept in a healthy state by bathing, rub- 

 bing, etc. Exposure to sudden changes of temperature should 

 be avoided as far as possible. Flannel worn next the skin, in 

 all seasons of the year, is an excellent precaution against un- 

 avoidable exposure. 



17 What causes the difference between the hard hand 

 of a blacksmith and the soft hand of a woman ? 



(See Physiology, p. 50.) 



The varying thickness of the cuticle. 



