XII. B, 1 Shaklee: Experimental Acclimatization 19 



cerned with the stimulation of the sweat glands seem to be 

 especially affected. 



However, it must not be forgotten in this connection that there 

 may have been other conditions operating to raise the resistance 

 of these monkeys to heat. For example, the change in diet to 

 which each monkey was subjected when it was placed under ob- 

 servation may have aided in increasing its resistance. Observa- 

 tions by the author in connection with experiments on man 

 indicate that in man some diets lower the resistance to heat 

 and others raise it. Whether or not the change in the monkey's 

 diet was sufficient to affect its resistance remains to be ascer- 

 tained. The fact that monkeys, partially acclimatized, kept 

 in the shade on the same light diet, seemed to loose in powers 

 of resistance indicates that the diet here plays a minor role. 



The significance of this acclimutization of monkeys for the 

 acclimatization of man. — Since a moderate ability to sweat and 

 a light, suitable diet are sufficient to render the monkey practi- 

 cally immune to the worst combinations of weather conditions 

 that occur in a tropical region such as that in which Manila lies, 

 it would seem that man might readily be acclimatized to the 

 same conditions. There are many facts that point in this 

 direction. Man seems in every way better adapted than the 

 monkey to resist the tropical climate. The monkey is ordinarily 

 easily killed by heat stroke as has been shown by the experiments 

 of Aron and by the experiments here reported. It may be, 

 as Aron stated, that the monkey is less resistant to the worst 

 combinations of tropical weather than the white man. The tem- 

 perature-regulating mechanism in man is much more sensitive 

 than that in the monkey, as shown by the smallness of the 

 normal variation of body temperature in man as compared with 

 that in the monkey. The sweating mechanism in man has 

 many times the capacity of that in the monkey, and as the 

 temperature of the surrounding atmosphere approaches the tem- 

 perature of the body, this becomes the most important means 

 of eliminating heat from the body. The internal heat produc- 

 tion of man on a light diet is smaller in proportion to body 

 surface than that of the monkeys subjected to this experiment. 

 Man stands higher above the hot surface upon which he rests 

 or moves; hence he would received less heat from the ground 

 and be subjected to a more rapid movement of air over the 

 body surface than would the monkey. Man's body has much 

 less hair than the monkey's; hence the escape of heat from his 

 body by radiation, conduction, or evaporation is less interfered 



