246 APPLIED PHYSIOLOGY 



again, and there is a feeling of warmth, although the ice still continues 

 to cool the hand. 



102. Take some cotton and some woolen cloth of equal thickness. 

 Wet them and notice how much more quickly the cotton will dry than 

 the wool. Wrap them around the hand and notice that the woolen 

 feels warmer, because evaporation from it does not carry heat away 

 from it so fast as from the cotton. Then blow upon them and notice 

 how much colder the cotton feels. 



103. Place two pieces of ice of equal size in the sun and cover one 

 with a black cloth and the other with a white piece of the same kind, 

 and notice that the piece under the black cloth melts faster. 



104. Needles of water crystals can be shown by setting aside a cup 

 of water out of doors until it just begins to freeze, if it is a cold day, or, 

 if it is a warm day, by putting a large piece of ice in the sun and break- 

 ing it when it is half melted. Each needle is pure water. 



105. A wasp or a fly will illustrate the hibernation of animals. In 

 winter a few wasps can usually be found in a sunny garret window. 

 When the air is quite warm, the wasps will be lively, and as it becomes 

 colder they become more sluggish, until at night they are apparently 

 lifeless. 



REVIEW TOPICS 



1. Give the temperature of the body and tell how the 



heat is distributed. 



2. State what causes sensations of heat and cold, and 



how the body may feel warm while it is cold, and 

 cold while it is warm. 



3. State how the production of heat is regulated. 



4. State how the amount of blood in the skin regulates 



the amount of heat given off. 



5. State how the perspiration regulates the amount of 



heat given off. 



6. State how tight bands about a limb cause cold feet or 



hands. 



7. Give the best temperature of living rooms and of bed 



rooms. 



