16 The Philippine Journal of Science i»i7 



Nature of this acclimatization^ — In this research facts have 

 been brought out that give some information as to the nature 

 of the acclimatization produced. 



First, acclimatized monkeys sweat much more than unacclima- 

 tized monkeys when placed on a hot surface in the sun. Aron • 

 had stated that monkeys have no sweat glands and I, not having 

 had occasion better to inform myself on this point, was greatly 

 surprised soon after I had begun these experiments on acclima- 

 tization to notice, while watching a monkey in the sun, small 

 beads of sweat glistening in the hair of its forehead. After 

 this I made systematic examinations of the surfaces of the 

 monkeys' bodies in order to get some idea of the amount of 

 sweating. I regularly found beads of sweat on the heads of 

 acclimatized monkeys placed on the roof in the sun, if the roof 

 was very hot. Sweat was found on the backs of the monkeys 

 also, being greater in quantity on the upper back and gradually 

 diminishing in quantity toward the tail. At the root of the tail 

 comparatively little sweat was found. The palms were fre- 

 quently found wet with sweat, and they often left wet imprints 

 when lifted from the surface of the asphalt roof. On other parts 

 of the body I found very little sweat. On some parts I did not 

 succeed in finding any, but since the skin seems everywhere 

 provided with well-developed sweat glands, it seems probable 

 that there was insensible perspiration over the areas that did 

 not show visible sweat. I found, therefore, that the acclima- 

 tized monkey sweats a good deal while resting on a hot roof 

 in the sun. On the contrary, I found that the unacclimatized 

 monkey sweats very little, if at all, under like conditions. This 

 difference in perspiring between acclimatized and unacclimatized 

 monkeys was very striking, so striking that one might be justi- 

 fied in inferring that it was because of this difference in sweat- 

 ing that the body temperature of the acclimatized monkey, under 

 conditions that cause a rapid and fatal rise in the body tem- 

 perature of the unacclimatized, does not rise above the maximum 

 normal. 



Secondly, it was found that a small dose of atropin sulphate 

 caused a marked rise in the body temperature of an acclimatized 

 monkey exposed to a hot sun. Atropin has been found to dimin- 

 ish the action of sweat glands by depressing the secretomotor 

 nerve endings in the glands and so preventing nerve impulses 

 from stimulating the secretory cells. Each time that I injected 

 a small dose of atropin sulphate under the skin of an acclimatized 



* Aron, op. cit., p. 110. 



