232 ANIMAL HEAT. 



influences ; and the difference which under these circum- 

 stances exists, depends chiefly upon the different degrees of 

 blood-supply. In the arm-pit the most convenient situa- 

 tion, under ordinary circumstances, for examination by the 

 thermometer the average temperature is 98 '6 F. 



The chief circumstances by which the temperature of the 

 healthy body is influenced are the following : 



Aije. The average temperature of the new-born child is 

 only about l F. above that proper to the adult ; and the 

 difference becomes still more trifling during infancy and 

 early childhood. According to Wunderlich, the temperature 

 falls to the extent of about 4. to J F. from early infancy 

 to puberty, and by about the same amount from puberty to 

 fifty or sixty years of age. In old age the temperature 

 again rises, and approaches that of infancy. 



Although the average temperature of the body, however, 

 is not lower than that of younger persons, yet the power of 

 resisting cold is less in them exposure to a low temperature 

 causing a greater reduction of heat than in young persons. 



The same rapid diminution of temperature was observed 

 by M. Edwards in the new-born young of most carnivorous 

 and rodent animals when they were removed from the 

 parent, the temperature of the atmosphere being between 

 50 and 53^ F. ; whereas, while lying close to the body of 

 the mother, their temperature was only 2 or 3 degrees 

 lower than hers. The same law applies to the young of 

 birds. Young sparrows, a week after they were hatched, 

 had a temperature of 95 to 97, while in the nest; but 

 when taken from it, their temperature fell in one hour to 

 66J, the temperature of the atmosphere being at the time 

 62 J. It appears from his investigations, that in respect 

 of the power of generating heat, some Mammalia are born 

 in a less developed condition than others ; and that the- 

 young of dogs, cats, and rabbits, for example, are inferior 

 to the young of those animals which are not born blind.. 

 The need of external warmth to keep up the temperature 



