BODY TEMPERATURE OF MICE 319 



2. TEMPERATURE TESTS OF ADULT AND NEARLY ADULT MICE 



1. Methods 



In all, 198 temperature determinations were made in the course 

 of this series of experiments. Fifty-one white mice were used 

 for the purpose, of which 43 were males and 8 females. All of the 

 females and most of the males were fully mature, having an age 

 ranging from eight to twelve months. For certain experiments 

 there were included some males (15 in all) which were about 

 three and one-half months old. These last were, however, of good 

 size, averaging about five-sixths of the weight of the adult males. 



Twenty-three of the mice which were used belonged to a lot 

 which had been kept for eight to sixteen weeks in an artificially 

 heated room, the remainder having been kept during the same 

 period in a much colder room. The mean temperature of the 

 former, up to the time of the first experiment (January 14), ^ 

 was 22.3°C., the mean daily range being 9°C. The mean temper- 

 ature of the cold room up to the time of the first experiment 

 (January 16) was 5.8°C.,i'' the mean daily range being 7°. 



Unfortunately, my control over the temperature of the warm 

 room was at times quite inadequate. The extreme temperatures 

 recorded for the entire period were 5° and 36.7°C., but both of 

 these conditions were very exceptional and of brief duration. The 

 temperature of the cold room did not ordinarily differ much 

 from that of the air outside. The extremes for this room were 

 — 11.1° and -1- 17.8°, but these conditions were likewise excep- 

 tional. The temperature tests were made during the colder 

 months of the year when the atmosphere of the two rooms nat- 

 urally differed most widely. 



The temperatures of the mice were determined by means of 

 specially constructed mercury thermometers, inserted in the rec- 

 tum. The instruments were made to order by the Randall- 



' If computed to the time of the last experiment (April 1) the mean temperature 

 would be almost exactly the same, viz., 22.4°. 



1° If computed to the time of the last experiment (March 1) the mean would be 

 4.4°. 



