BODY TEMPERATURE OF MICE 337 



The females alone show us a considerably lower mean figure 

 for the cold-room lot, the difference being 0.76°, 0.95°, or 0.88°, 

 according to which pair of averages is used for the comparison. 

 Moreover, the variability is here comparatively small, the stan- 

 dard deviations be'ng only 0.28° for the warm-room lot and 0.5° 

 for the cold-room lot. It may be pointed out that the mean dif- 

 ference in the temperature of the two rooms, during the tests in 

 which these females were used was about 32°C., or 8° greater 

 than that during the tests with the adult males. It is possible, 

 however, that female mice are more readily affected by differ- 

 ences of atmospheric temperature than are males. Some slight 

 evidence of this has already appeared. But the data at our 

 disposal are far too limited to decide the question. 



It is obviously not allowable to throw together all of the read- 

 ings from the warm-room individuals (older and younger males, 

 and females), and to compare the average thus derived with a 

 similar figure derived from all of the cold-room determinations. 

 We may, however, obtain a value which will represent, in a rough 

 way, the mean difference between the two lots as a whole. For 

 the separate groups of ind viduals, we have found the following 

 differences, based upon the 'thirty-second' figures: 



Differences (warm — cold). 



Adult males +0 .05° 



Younger males (three and one-half months) —0.17° 



Females +0.76° 



To give these last figures equal value in finding their average, 

 would not be allowable, since the first depends upon results de- 

 rived from 13 warm-room and 15 cold-room tests, the second 

 upon results from 5+6 tests, and the third from 6+9 tests. We 

 may, however, Veight' these figures in accordance with the num- 

 ber of tests which they represent, and then proceed to obtain 

 the average.^'- The result is a difference of 0.16°, in favor of the 

 warm-room set. This, it will be noted, is based upon 24 warm- 

 room tests and 30 cold-room tests. The mean air temperature 



'2 That is, multiply the first by 13 X 15 (= 195), the second by 5 X 6 (= 30), 

 and the third by 6 X 9 (= 54). The sum of these products is divided by 279. 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 15, NO. 3 



