18 FREER. 



of the darker skin, the highest of all observations being 37°. 4 

 in an American, on the cheek, after exposure for twenty-five 

 minutes. 



These measurements, while showing conclusively that the 

 adaptable mechanism for heat regulation possessed by human 

 beings is sufficient to lower the temperature and protect the 

 individual from such fatal effects as are observed in monkeys, 

 still did not appear sufficiently conclusive as regards the dif- 

 ferences between the white and dark skins. Therefore, both 

 for the purpose of comparing the effects of insolation at high 

 altitudes with those at sea-level as well as for a further study 

 of the possible differences between the two colors, the experi- 

 ments of Aron were repeated in Baguio by H. D. Gibbs of the 

 laboratory of organic chemistry of the Bureau of Science. The 

 skin temperature in Baguio rose to higher points than those 

 observed by Aron in Manila. 



This may in part be accounted for by the technique employed, for Aron 

 warmed the thermometric junction in the palm of the hand and then placed 

 it on the part of the skin to be measured, whereas Gibbs commenced 

 measurements a short distance from the desired spot and, as soon as the 

 maximum deviation of the galvanometer was reached, moved the ther- 

 mocouple nearer the place, and when the instrument was again at rest, 

 placed it in the final position. However, after taking the differences in 

 technique into consideration, the absolute values recorded for the upper 

 altitude are still higher than those for the lower. 



Comparison between an American and two dark-skinned 

 Igorots, A and B, taken over the level of the third dorsal ver- 

 tebra, the fifth dorsal vertebra, and over the upper angle of 

 the scapula, in the order named, were as follows: The average 

 of shade temperatures of all subjects being 30°. 06, 32°. 4, and 

 33°. 52, but it must be recorded that a slight breeze affected the 

 American's temperature. After twenty-seven minutes the Amer- 

 ican reached maxima of 37°. 65, 37°. 15, and 37°.95; Igorot A, 

 after thirty-six minutes, measured 38°. 05, 38°. 35, and 37°. 9; 

 whereas Igorot B, after thirty-three minutes, recorded 37°.4, 

 37°. 9, and 36°. 8, or temperatures averaging 4-0°.73 against the 

 dark skin of A and — 0°.05 in favor of B. The thigh of A, 

 which was steadily exposed to the sun, showed the remarkable 

 skin temperature of 52°. 7.^" 



" Wind screens were used to protect the subjects from the cooling effects 

 of the breeze, but occasional eddies would reach the men in spite of all 

 precautions. 



