CLIMATE 903 



about 15 miles per hour increased the metabolism approximately 19 per 

 cent. 



A recent investigation by Aggazzotti and Galeotti on the influence of 

 wind on the respiration and the pulse has shown that if the wind is not 

 too strong the lung ventilation is favored. The alveolar carbon dioxid 

 tension is lowered. In strong wind the breathing shows irregularity in 

 rate and depth. 



Light 



The opinion has been held that the intense light of the tropical skies 

 causes the backwardness of mankind in these countries. Sun baths have 

 been employed in the treatment of tuberculosis with some degree of success. 

 However, the physiological effects of light have not been clearly demon- 

 strated. Wohlgemuth, in a study of desert climates at Assuan, found 

 the number of red corpuscles and the per cent of hemoglobin to be slightly 

 increased. That the increase was not the result of the loss of water from 

 the blood because of sweating was shown by the observations that neither 

 the sodium chlorid nor the sugar content of the blood was changed. He 

 attributes the increase in red corpuscles, which in one man rose from 

 4,900,000 to 5,680,000 in five months, to the action of light; and cites 

 that Bickel, on exposing rabbits to the light of the mercury arc, produced 

 an increase in the red corpuscles. Other possibilities were not eliminated. 

 Huntington, in his investigation on human efficiency, as measured by the 

 amount of daily work performed, found that the effect of light was at 

 best only slight. 



Rubner, under ordinary conditions, and Durig and Zuntz, on Monte 

 Rosa, did not find that sunlight influenced metabolism. Hasselbalch and 

 Lindhard(a), studying the ultra-violet rays of the sun, obtained no effect 

 upon the metabolism. They did, however, find a reduction in the fre- 

 quency and an increase in the depth of respiration as the effect of the 

 exposure to such rays. 



The importance of climatic conditions in the life and efficiency of 

 mankind has been well demonstrated by Ellsworth Huntington in his 

 book on "Civilization and Climate." He points out that for the pro- 

 duction of good fruit the three factors of good stock, proper cultivation, 

 and favorable climatic conditions are absolutely necessary. Recognizing 

 the importance of these three for man, he then proceeds to study con- 

 ditions of human progress and power of achievement He finds that 

 wherever civilization has risen to a high level, the climate appears to have 

 possessed those qualities which to-day are recognized as most stimulating. 

 He derives the important climatic factors by various statistical com- 

 parisons. Assuming that the best and fullest test of efficiency is a person's 

 daily work, the thing to which he devotes most of his time and energy, ho 



