BODY TEMPERATURE OF MICE 317 



Thus, if the 9-cm. readings be the ones employed, the body 

 temperature, after exposure to the cold atmosphere, is 0.31° lower 

 than after exposure to the warm. If the 2.5-cm. readings be con- 

 sidered, the difference is 0.50°. 



Pembrey^ experimented at considerable length upon mice and 

 other animals, chiefly in relation to the effects of external tempera- 

 ture upon the output of carbon dioxid. His temperature figures 

 for adult mice under different atmospheric conditions are so few 

 and so variable that they can hardly be introduced as evidence 

 in the present discussion. As regards young animals, however, 

 Pembrey offers more valuable data, and these will be referred 

 to again in the course of this paper. 



Hill and Macleod^ found that in a current of very moist air, 

 even at temperatures as high as 20°C., mice lost the power of heat 

 regulation and acquired a temperature little, if any, higher than 

 that of the atmosphere. Such phenomena are to be regarded as 

 pathological, however, and throw little light on the present sub- 

 ject (see p. 343 below). 



Macleod^ subjected rats to relatively high temperatures, both 

 in moist and dry air. As the result of a sojourn of a half hour 

 at a temperature between 36° and 39°C., rats were found to 

 undergo a rise of several degrees (nearly 4° in one case) . This, 

 likewise, cannot be regarded as a normal phenomenon, and the 

 conditions were certainly not comparable with those which ob- 

 tained in any of my own experiments. 



Congdon, ^ working in Przibram's laboratory, recently attacked 

 this problem with the same object as the present writer, namely 

 to determine the possibility of a direct effect of atmospheric tem- 

 perature upon the germ-cells of mammals. Rats and mice were 

 used for these experiments. Congdon's own summary of his re- 

 sults is quoted herewith: 



1. Adult rats (Mus decumanus) reared at 33° have a rectal tempera- 

 ture of 37.2°; at 16°, 36.2°. There is thus a difference of 1°. 



5 Journal of Physiology, vol. 18, 1895, pp. 363-379. 



« Journal of Physiology, vol. 29, 1903, pp. 492-510. 



^ American Journal of Physiology, vol. 18, 1907, pp. 1-13. 



* Archiv fur Entwicklungsmechanik der Organismen, 33 Bd., 1912, S. 703-715. 



