erased like any other muscles if they are to be kept in good 

 condition. In a person who lives habitually in an even 

 high temperature the blood vessels do not respond readily 

 to sudden change. In such people, the mucous membranes 

 of the nose are constantly congested (filled with blood and 

 lymph) as the blood vessels dilate to keep the body at the 

 proper temperature. As a consequence, these membranes, 

 instead of shrinking and drying promptly as they should 

 when they come in contact with cold outer air, lose their 

 quickness of response and stay moist and swollen even after 

 the blood vessels themselves have contracted; this makes 

 them an excellent breeding place for bacteria. People who 

 have been weakened in this way are very sensitive to the 

 cold air and are easily subject to chills. Benjamin Franklin 

 once said, "People who live in the forest, in open barns, or 

 with open windows, do not catch cold, and the disease called 

 a cold is generally caused by impure air, lack of exercise, 

 or from overeating." Science has amply confirmed these 

 observations of our great natural philosopher. 



Fresh air, then, means air that is not too hot, or too cold, 

 or too even in temperature, — air that is w « „ , 

 pleasantly cool and in moderate motion. .. T 

 If the thermometer reaches 70° (except in the 

 case of elderly people, who may require a higher tempera- 

 ture) it is a sign that the window should be opened. It is 

 particularly important to have plenty of fresh air in the 

 sleeping room and windows should be kept well opened at 

 night even in cold weather. 



HYGIENE OF CLOTHING AND BATHING 



The clothing should protect against extremes of cold, and 

 this is particularly necessary after exercise n ... - 

 when the skin blood vessels are dilated and /£ f| , . 

 the body bathed in perspiration. Woolen 

 clothes may be desirable under such conditions because 



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