336 TEMPERATURE OP WARM-BLOODED ANIMALS. 



to be the case among Mammals. There are some species 

 (such as the Guinea-pig) whose young are able from birth to 

 walk and run, and to take the same food with the mother ; 

 and these have from the first the power of maintaining a 

 steady temperature when the air around is not very cold. 

 But, in general, the young of Mammals are much less advanced 

 at the time of birth, being not unfrequently born blind as 

 well as helpless j and they require considerable assistance, in 

 keeping up their heat, from the parent or nurse. Thus the 

 temperature of new-born puppies, removed from the mother, 

 will rapidly sink to between 2 and 3 above that of the air. 



409. These facts are of extreme practical importance, in 

 regard to the treatment of the Human infant. Though not 

 destitute of sight, at its entrance into the world, like the 

 young of the Cat, Dog, or Rabbit, it is equally helpless, and 

 dependent upon its parent not only for support but for 

 warmth. And as the Human body is longer in arriving at 

 its full development than is any other, so is it necessary that 

 this assistance should be longer afforded. This assistance is 

 the more necessary in the case of infants born prematurely ; 

 and it should be kept up during the years of childhood, 

 gradually diminishing with age. It is too frequently neglected, 

 by those who are well able to afford it, under the erroneous 

 idea of hardening the constitution ; and the want of it, con- 

 sequent upon poverty, is one of the most fertile sources of the 

 great mortality among children of the poorer classes. This 

 is easily proved by the proportional number of deaths which 

 take place in different parts of the year, at different ages. 

 During the first month of infant life, the winter mortality is 

 nearly double that of the summer ; though there is very little 

 difference between the two seasons in the mortality of adults. 

 But in old age the difference again manifests itself to the 

 same amount as in infants ; for old persons are almost equally 

 deficient in the power of maintaining heat; they complain 

 that their " blood is chill," and suffer greatly from exposure 

 to cold. 



410. The class of INSECTS presents us with some very 

 interesting phenomena. In the larva and pupa states, the 

 temperature of the body is never more than from J to 4 

 above that of the surrounding medium ; but, in many tribes, 

 the temperature of the perfect' Insect rises so high, when it is 



