RESPIRATION 193 



movement of all the muscles concerned in respiration. It 

 has been noticed that men and infants use the abdominal 

 muscles and those of the lower part of the chest more 

 than women do. This is not because women have a 

 sort of breathing apparatus different from that of other 

 human beings, but because their clothing is too frequently 

 worn so tight that full and free respiration is impossible, 

 the various organs being displaced and deformed, and the 

 whole system weakened, while to the artistic eye the fig- 

 ure appears distorted and ugly. 



One .should accustom himself to go often into the open 

 air and draw long, full, and deliberate breaths, followed 

 by slow expiration, in order that all the minute air cells 

 of the lungs may be filled and their walls expanded. 

 Those which are habitually unused may become perma- 

 nently collapsed and hardened, and the capacity of the 

 lungs be thus reduced, the whole system being weakened 

 and prepared to fall an easy prey to disease. 



274. Temperature of Air for Breathing. Man is able to 

 live a healthy life in the most torrid climates and in 

 regions where the air is many degrees below the freezing 

 point. He can even remain for some time unharmed in a 

 chamber heated far above the boiling point of water. 

 Such are the marvelous adjustments of which his organ- 

 ism is capable. 



But in connection with the artificial warming of closed 

 rooms, it is necessary to inquire as to the most healthful 

 temperature of the air habitually breathed. Most people 

 in America live, in winter, in rooms too hot for health, 

 and thus render themselves unnecessarily liable to " take 

 cold " on going out. A living room for adults in ordinary 

 health should have a temperature of from 65 to 70 F, 

 (18 to 21 C.). For young children, the aged, or the 



