47 



the difference arose from the want of covering ; but the 

 careful envelopment of the unfledged bird in down, and 

 the removal of the feathers of the fledged bird, made no 

 other difference in the result, than that the extreme depres- 

 sion of temperature in the former instance was attained in 

 a longer time. The young of the human species are born 

 with their eyes open, and they also retain the power of pre- 

 serving their temperature at a fixed point, a little below that 

 of the mother. But there are instances in which the child 

 is born-before its time, viz., at the seventh month, and in 

 these cases it is found that the greatest precautions are 

 requisite to prevent the temperature sinking indefinitely. 

 A child born at the full period; the temperature of 

 the mother being J 00°, was able, when separated, 

 to preserve its own temperature at 95°. A child born 

 at the seventh month, perfectly healthy, and which 

 had come into the world with so little difficulty, that 

 the accoucheur could not arrive in time, had been 

 well clothed by a good fire, when the temperature was 

 taken at the axilla and found to be 89° 6' only. The 

 period at which, after birth, the animal attains the perfect 

 power of preserving its temperature at that of the adult, 

 varies in different animals ; in some it is attained in a few 

 months, in the human infant it is not attained until the 

 fourth year. From that period, until the 16 th year, its 

 temperature is higher than that of the adult; at 16 the 

 adult temperature is established, until the approach of old 

 age, when the phenomena are reversed in an order that has 

 not been so exactly observed. In order to explain the 

 progress of the temperature in the human being, I will again 

 anticipate some of the conclusions with regard to the several 

 sources of heat. I have spoken of these as dependent upon 

 the chemical combinations and separations which, under 

 vital influence, are performed in the exercise of the func- 

 tions of the animal. In the early period of life, these are 



