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FEANCIS B. SUMNER 



mal temperature of man in the tropics is believed by the majority 

 of investigators to be somewhat higher than it is in temperate 

 zones, though the difference is probably considerably less than 

 1°C. Hibernating mammals, and most others while in very im- 

 mature stages, are known to lack the power of temperature control 

 almost entirely. 



For mammals in general, the available information regarding 

 the influence of atmospheric temperature upon that of the body 

 is rather meagre. More than eighty years ago, W. F. Edwards' 

 exposed various mammals and birds, both young and adult, to 

 low temperatures. He recorded great reductions of body tempera- 

 ture in the young of various species, and lesser changes even in 

 the adults. "Guinea-pigs, and adult birds [when subjected to 

 a temperature of 1°C.] lost, at the utmost, no more than two 

 or three degrees." Adult mice, upon exposure to "a moderate 

 cold in winter," underwent a reduction in temperature which 

 "surprized" this author, though we are not given the figures. 

 The observations of Edwards upon very young mammals will be 

 considered more fully later. 



Finkler^ exposed guinea-pigs to varying atmospheric tempera- 

 tures, thereby inducing constant small differences of body tem- 

 perature. Finkler likewise called attention to the very consider- 

 able differences in the thermometer reading which resulted from 

 inserting the bulb to various depths in the rectum of the animal. 

 His figures may be summed up as follows : 



TABLE 1 



^ On the influence of physical agents on life (translation from the French). 

 London, 1832, pp. 488. 



^ Archiv fiir die gesammte Physiologie, Bd. 29, 1882, S. 98-244 (particularly 

 111-125). Taf. II. 



