BODY TEMPERATURE OF MICE 343 



lished, but Dr. Congdon has kindly shown me some of his original 

 notes, and the variablity among his figures appears to be nearly 

 or quite as great as among my own. 



6. Exceptionally low body temperatures 



The temperatures hitherto discussed have been within strictly 

 physiological limits. The changes have, at most, amounted to 

 1° or 2°, and it has not been necessary to return the animals 

 to a more normal atmosphere in order that death should be 

 averted. 



In two instances, however (27-1 and 20-1, in table 8), the mice 

 quite lost their power of temperature control, and would doubt- 

 less have died unless restored to a much warmer environment. 

 The body temperature fell to 20.6°, in one case, and to about 

 12.5° in the other, after an exposure of about five hours to an 

 atmosphere ranging from —2° to +2°. The mouse which re- 

 corded the lower temperature was scarcely living at the end of 

 this period, the only signs of life being certain reflexes and occa- 

 sional gasping. Nevertheless, even this animal became fairly 

 active after one and one-half hours in the warm room (then 28.5°), 

 and was seemingly well after four hours. No harmful effects 

 were noted later. 



Edwards^" and some subsequent writers, notably Pembrey and 

 White, ''^ have shown that hibernating mammals normally reach 

 extraordinarily low temperatures (even 2°) during the winter. 

 In the experiments of Hill and Macleod, already cited, a tem- 

 perature as low as 17° was obtained by subjecting a mouse to 

 moist air, which, however, was not cold, in the sense in which 

 the word has been employed in the foregoing discussion, but had 

 the very moderate temperature of 18°. Even human beings, 

 exposed to the cold, during intoxication have been reduced to a 

 temperature of 24°C., without fatal consequences. 



4" Op. cit. 



" Proceedings of the Physiological Society (bound with the Journal of Physi- 

 ology, vol. 18, 1895), pp. xxxv-xxxvii. 



