STUDY OF THE EFFECT OF TROPICAL SUNLIGHT. 105 



The experiments were conducted in such a way that ail of the 

 subjects handled at one time received equal treatment. When 

 exposed to the sun. they were placed side by side with only a 

 few centimeters of space between any two animals. The sub- 

 cutaneous temperatures were taken through a small orifice in the 

 skin of the lower dorsal region. Three rabbits, one of each 

 color, were employed in each series in order to bring out any 

 differences due to color. It was found that the thermocouple 

 came to rest in a few seconds and could be transferred from 

 rabbit to rabbit so quickly that all three could be measured quite 

 accurately in from thirty to forty seconds. 



The subjects were put in the sun at 9.10 in the morning, and 

 remained exposed until 9.46, at which time they were returned 

 to their cages for the reason that the clouds were becoming so 

 heavy that the work could not be continued with profit. The 

 white and gray rabbits soon recovered from the exposure, were 

 lively, and ate with relish. The black rabbit recovered a little, 

 but soon relapsed, and died at 12.30 in the afternoon. 



Before the second series of experiments was begun, it appeared 

 that the results would be unsatisfactory for the reason that the 

 physical condition of the three rabbits employed was so different. 

 The black and gray were large, strong, and healthy specimens, 

 while the white rabbit was small and thin, and had every appear- 

 ance of being a weakling. 



Table X. — Summary of the physical characteristics of the three rabbits. 



Color. 



Fur. 



Skin. 



Black . . 



Moderately thick 



Moderately thick. 



Gray . 



Very thick 



Very thick. 



White 



Thin 



Thin. 









The gray had every appearance of being stronger than the 

 black, although the difference between the two was not so marked 

 as that between the black and the white. Under the circum- 

 stances it would not have been at all surprising had the white 

 died first. In view of the fact that the black died in thirty- 

 three minutes, the gray in one hour and thirty-two minutes, 

 while the white recovered and is alive at this writing, several 

 days later, the experiment is as convincing as it is possible for 

 any one piece of work to be. 



