340 FRANCIS B. SUMNER * 



for the males and 1.0° for the females. ^^ In table 8, five adult 

 males exhibited a mean reduction of temperature of 0.58°, five 

 hours after a change from 14° to about 0°. Indeed only three of 

 the five showed any reduction at all in this interval. ''^ In table 

 10, two males and two females, following a fall of 19 degrees in 

 twenty-four hours, showed body temperatures averaging only 

 1.4° lower than they were ten days later, when the air tempera- 

 ture was 18° higher. (Here, again, one of the males showed no 

 reduction whatever.) These cases, taken singly, are not fully 

 convincing, in view of the variability of the figures, but their 

 cumulative weight is considerable. 



It is, however, the question of permanent differences between 

 the two respective sets of mice which especially concern us here. 

 The evidence regarding these has been summarized so recently 

 that I need not repeat it. No difference of any significance, 

 statistically considered, was demonstdrated for the males (either 

 young or old) ; while the females showed a difference of only about 

 0.75°, when subjected to a mean difference in air temperature of 

 32°. Congdon's rats showed a mean difference of 1°, as a result 

 of living in temperatures differing only by 17° 



Congdon gives as the result of averaging "the temperatures of 

 animals at puberty and of older animals, living at medium tem- 

 peratures," the mean figure of 34.9° for the white mouse. More 

 surprising still, the mice which were transferred by Congdon to 

 a temperature of 5° showed a mean body temperature of 31.2°, 

 while in no case did I observe a temperature as low as this by 

 several degrees." 



While doubtless my warm-room temperatures were more nearly 

 'medium' than the cold-room ones, I have computed the mean 

 of the six averages for the 'thirty-second' figures, given on pp. 

 335-336 above,3« the result being 36.66°. This figure, which is 

 based on 54 readings, is higher than Congdon's by 1.8°C. 



'^ Compared with the first tests for the day on two other days at the normal 

 temperature of the room. 



^^ No mention is here made of the young males, since Congdon himself found 

 much smaller changes among these. 



'^ Except for the extreme cases of subnormal temperature, already mentioned. 



