336 TEMPERATURE OF 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 ; 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 Inszcts presents us with some very 
interesting phenomena. In the larva and pupa states, the 
temperature of the body is never more than from }° to 4° 
above that of the surrounding medium ; but, in many tribes, 
the temperature of the perfect Insect rises so high, when it is 
