August 11, 1916] 



SCIENCE 



187 



ence, and it is often interpreted as real in- 

 ability to work. The New York Commission 

 found, in their experiments with human 

 beings, that, if pushed, the individual is 

 capable of performing as much muscular 

 work in an atmosphere of 30° C. (86° F.) 

 and 80 per cent, relative humidity as in one 

 of 20° C. (68° F.) and 50 per cent, humid- 

 ity, but that he is not inclined to do so 

 much. The lack of exact knowledge as to 

 what the muscles themselves apart from the 

 nervous system can do under such circum- 

 stances induced Scott and myself 8 to inves- 

 tigate the subject on animals. Taking the 

 comfortable condition of 20.6° C. (69° F.) 

 with 52 per cent, relative humidity as our 

 standard, we found that when cats were 

 confined for six hours in a well-ventilated 

 chamber, the air of which was kept at an 

 average temperature of 32.8° C. (91° F.) 

 and an average humidity of 90 per cent., 

 the excised muscles of the animals lost 

 in the length of their working period 

 before exhaustion 11 per cent, and in the 

 total amount of work which they were able 

 to perform 24 per cent. At an intermediate 

 temperature and humidity they lost in an 

 intermediate degree. These results indicate 

 that the distaste for physical labor which is 

 felt on a hot and humid day has a deeper 

 basis than mere inclination — the muscles 

 themselves are actually incapable of per- 

 forming as much work. "We found, more- 

 over, that in the extreme condition the 

 blood lost as much as 6 per cent, of its 

 sugar, and 2 per cent, when the intermedi- 

 ate condition was maintained. There is evi- 

 dently correlation between decreased blood 

 sugar and decreased muscular power, and 

 we have suggested that a physiological 

 adaptation is here indicated, such that 

 "when it is physiologically fitting that the 

 animal reduce muscular exertion to a mini- 



8 Lee and Scott, Am. Jour, of Physiol., XL., 

 486, 1916. 



mum, in order that the output of heat may 

 be as low as possible, as in a hot and humid 

 environment, the supply of fuel will be 

 lowered correspondingly. ' ' 



Little can be said at present regarding 

 the action of atmospheric conditions on the 

 nervous system. The rise of external tem- 

 perature by dilating the cutaneous blood 

 vessels undoubtedly makes the brain anemic, 

 but it is not certain that variations in such 

 temperature with or without variations in 

 humidity markedly affect the action of the 

 nerve tissues, unless the variations are ex- 

 cessive. The New York Commission, under 

 the lead of Thorndike, has expended much 

 time and effort in endeavors to detect a pos- 

 sible influence of atmospheric variations 

 between moderate limits on the ability to do 

 mental work. The subjects were given 

 such psychological tests as cancelling arith- 

 metical figures, adding figures, mentally 

 multiplying three-place by three-place fig- 

 ures, typewriting, and more complex mental 

 performances which involve choice and 

 judgment. The range of atmospheric vari- 

 ation was from a lower limit of 20° C. 

 (68° F.) and 50 per cent, relative humidity, 

 and an upper limit of 30° C. (86° F.) and 

 80 per cent, humidity. In some cases the 

 air was quiet, in others it was kept in mo- 

 tion by electric fans. The tests continued 

 for periods of from 4 to 7 hours and in 

 some cases they were repeated for 6 suc- 

 cessive days under the same conditions. In 

 neither the young men nor the young wo- 

 men subjects of these tests could there be 

 detected any relation between atmospheric 

 conditions and either the accuracy or the 

 amount of the mental work that was per- 

 formed. A series of experiments on a 

 larger scale has been instituted, but is not 

 yet completed. 



The relation between atmospheric condi- 

 tions and metabolic phenomena is not yet 

 elucidated. During the summer of 1914 the 



