BODY TEMPERATURE OF MICE 351 



reached until two or three minutes after the insertion of the 

 thermometer. This rise was less marked, however, than in the 

 warm room. 



In general, the fall in temperature, following the fatal incision, 

 was perhaps more rapid in a mouse two or three weeks old than 

 in one five to ten days old, but there was no constancy in this 

 regard. 



SUMMARY 



For adult and nearly adult mice the following conclusions may 

 be offered: 



1. The most striking feature of a set of temperature records 

 of these animals is the great variability among the figures. Dif- 

 ferent animals, under seemingly identical conditions, differed as 

 much as 1° or 2°C. in their bodj^ temperatures, while the same 

 individual, in the course of a few minutes, might exhibit differ- 

 ences nearly or quite as great. 



2. One of the chief causes of such temperature differences is 

 the degree of excitement or agitation of the animal. To this 

 must be added, perhaps, local congestion, due to the insertion 

 of the thermometer into the rectum. Thus, a comparison of the 

 first and second temperature readings for the day, when the 

 interval between the two was less than an hour, showed a mean 

 rise of about 1.5°, in the case of the adult males. 



3. The mean temperature of 8 female mice was found to be 

 0.76° higher than that of 8 male mice, in a series of tests in which 

 animals of opposite sex were compared with one another under 

 identical conditions. 



4. Nearly adult males, three and one-half months of age, were 

 found to have a temperature of 0.66° higher than fully mature 

 males f eight to twelve months old), the conditions being identical 

 for the contrasted sets. This conclusion is based upon a considera- 

 tion of -38 tests in which 24 mice were used. 



