14 FREER. 



were it not to lose it by radiation or convection (conduction), 

 and the rate of this loss increases in proportion to the energy- 

 added to the body by radiation, until an equilibrium is reached. 

 Black bodies, while absorbing the radiations readily, also radiate 

 readily, so that it may come about that a black surface, exposed 

 to the sun, may become little, if any, hotter than one of lighter 

 color under similar circumstances. 



It is a well-known fact that the ultra-violet rays are promptly 

 fatal to almost all the lower organisms, such as bacteria, amoebae, 

 and protozoa ; the heat effect on them being much less, and only 

 apparent in so far as above certain temperatures they can not 

 live. As we ascend high enough in the orders of animals, devices 

 for regulating the losses of heat begin to appear, until, in birds 

 and mammals, they are so well developed that but little variation 

 in blood temperature is observable under the most diverse con- 

 ditions of life, and hence a study of the effects of the lower rays 

 of the sun's spectrum on such organisms, under normal and 

 abnormal conditions, is most promising. 



Such a study was undertaken by Dr. Hans Aron of the 

 department of physiology of the University of the Philippines 

 in conjunction with our other sunlight work, and his first results 

 have recently appeared.^* 



The first problem was to construct apparatus for thermometric 

 work which could easily be handled so as to give the subdermal, 

 rectal, and skin temperatures quickly and accurately within 0°.l. 

 This was finally accomplished by a series of specially prepared 

 thermocouples, temperatures being read by a tangent galvano- 

 meter.25 



Perhaps the most instructive and interesting results were 

 obtained with monkeys, animals which naturally are at home 

 in the Tropics and which, we should suppose, would best be 

 able to withstand the effects of sunlight. The system of sweat 

 glands in monkeys is not so highly organized as in man ^8 and 



"* This Journal, Sec. B (1911), 6, 101. 



"/6id., 117. 



" Aron, Ihid., 110, makes the statement that monkeys have no sweat 

 glands. During the time at his disposal, as he was going on long leave, 

 Aron did not investigate this question completely. Doctor Shaklee of the 

 department of pharmacology, University of the Philippines, states that 

 monkeys do have sweat glands. See also Blaschko, Arch. f. mikros. Anat. 

 (1887), 30; Wimpfelheimer, Anat. Hefte (1907), 34, 492. Krause, Beitrage 

 z. Kenntniss der Haut d. Affen; Inaug. Dissertat., Berlin (1888) is not 

 available. Sweat glands have been found by Mr. Clark of the department 

 of anatomy. University of the Philippines, in the forehead, hands, feet, 

 axillse, and abdomina of our monkeys. 



