332 FRANCIS B. SUMNER 



in table 7. The tests of January 16, were made during a 'cold 

 wave', the temperature of the warm room falling 19°C. in the 

 course of fifteen hours. Data from 2 males and 2 females are 

 available. The former show an average temperature (maximum 

 figures) of 34.75°, on the cold morning, the latter an average 

 of 36.35°. The mean figures for the same mice, on two other 

 days when the atmosphere was normal, are 35.50° for the males, 

 and 37.37° for the females. The extent of the fall in body tem- 

 perature in this case appears to have been about 0.75° for the 

 former and 1.0° for the latter. -^ 



The converse question, that of the effect of a very consider- 

 able rise in temperature upon cold-room animals, w^as tested in 

 one experiment (table 11), in which the ten mice in question 

 were subjected to an abrupt change of about 23°. The signifi- 

 cance of the considerable rise in body temperature shown by these 

 mice five hours after the transfer is confused by the fact, already 

 recorded, that evening temperatures as a rule appear to be de- 

 cidedly higher than those manifested earlier in the day. Both 

 sets of animals (the younger and the older males) show a decline 

 during the night; the older still retaining a considerably higher 

 temperature than at the commencement of the experiment (higher 

 also, by about 0.7°, than that found for the warm-room males in 

 general), while the younger ones give about the same mean figure 

 as at the outset (slightly lower, in fact). It is perhaps worth 

 recalling here that the younger mice in table 8 likewise returned 

 more nearly to their normal temperature than did the older ones. 



Another opportunity for comparing the effects of widely differ- 

 ing temperatures upon the same mice is afforded by table 10. 

 The tests of January 16, 17 and 18 were all made when the air 

 temperature was several degrees below 0°. The tests of January 

 26, on the contrary, were made when the air temperature was 11° 

 above zero, although there was no sudden rise to this point. If 

 we average the figures for the first three dates, on the one hand, 



2* It is true that these cold day tests were made in the morning, while the only 

 other available figures for these same mice were obtained early in the afternoon. 

 But comparison with morning figures for other mice does not justify the belief 

 that this circumstance has anything to do with the results stated. 



