

902 EDWAKD C. SCHKEIDER 



perature with draughts diminished the swelling, secretion and redness; 

 while cold draughts increased these conditions. The effects produced 

 upon the nasal mucosa are direct rather than reflex in nature. 



Miller and Xoble found that respiratory infection of rabbits was 

 favored by chilling after they had been accustomed to heat. They con- 

 clude that the weight of experimental evidence does not justify the 

 elimination of exposure to cold as a possible though secondary factor in 

 the incidence of acute respiratory disease. A change from low to high 

 temperature has even a more marked predisposing influence than that 

 from high to low. 



Environmental temperatures likewise exert an influence upon the 

 metabolism of men. Voit(e) subjected fasting men to many different tem- 

 peratures, in the Pettenkofer-Voit respiration apparatus, while he de- 

 termined the carbon dioxid and nitrogen elimination. Changes in tem- 

 perature from 57 to 80.6 F. scarcely changed the carbon dioxid output; 

 a lowering of temperature to 50 and less stimulated the metabolism; 

 also above 80.6 it was markedly increased, as shown by the rise in carbon 

 dioxid elimination. These observations on man are similar to metabolic 

 changes recorded by Rubner(/) for the dog and other animals. Rubner has 

 shown that increased humidity at temperatures above 82 F. increases 

 the metabolism. For a given high temperature the rise in metabolism 

 will not be as great where the evaporation of perspiration occurs readily 

 as when there is difficulty in evaporation, due to increased humidity, that 

 prevents effective elimination of heat. 



All studies on the influence of temperature and humidity indicate that 

 cool and comfortable atmospheres, with a temperature of about 68 F. 

 and 50 per cent relative humidity are beneficial ; while a temperature as 

 high as 86 F. and 80 per cent relative humidity are deleterious. The 

 bad effects are due primarily to the inability of the body to properly cool 

 itself because of the temperature and moisture conditions of the sur- 

 rounding air. 



Air Movement and Winds 



Here again the gain to the body is to be found chiefly in the influence 

 of moving air on heat loss. The air surrounding the body soon becomes 

 saturated with moisture and approaches the body heat in temperature. 

 Hence this tliin envelope of air surrounding the body may establish 

 the degrees of temperature and humidity that are known to be delete- 

 rious. 



The effect of wind of moderate humidity and different temperatures 

 on the metabolism of a man clad in summer clothes as compared with the 

 metabolism in calm air was shown by Wolfert(&) to be stimulating. A 

 breeze having a temperature of 59 to 68 F. and moving at the rate of 



