42 THE INFJiUENCE OF INANIMATE SUKEOBNDINGS. 



pagation, is not sufficiently energetic to raise the temperature 

 of the body perceptibly higher than that of the surrounding 

 medium, whether air or water. In such animals the need for 

 food may be in fact suspended for a long period, as their 

 vital processes can easily be reduced to a minimum without 

 endangering life. But, notwithstanding the privation of 

 nutrition, a certain consumption of organic constituents, how- 

 ever small, must be constantly going on ; for such a consumption 

 is inssparable from respiration, and this, even when 'reduced 

 to the lowest point, can never be wholly suspended without 

 endangering the life of the animal. Thus, in such cases, the 

 cessation of consumption of nutriment in no way proves that 

 the animal could have carried on an active life without food, 

 but only that its vital activity can be to a certain extent latent 

 for a long series of years ; still, not for all eternity';, on the 

 contrary it is perfectly certain that, even in an apparently latent 

 life, a certain consumption of organic tissues goes on, since with- 

 out it respiration, which is indispensable even when reduced 

 to the lowest point, is impossible, and so death must ensue even 

 with those animals that have the utmost powers of resistance. 

 Thus distinctions can only properly be made between the 

 difference in the amount consumed and the greater or less 

 resisting power as affected by that difference. Thus, for 

 instance, wami-blooded animals generally can scarcely live a 

 week without food, while cold-blooded animals can often support 

 life for many months without nourishment ; and it is extremely 

 interesting to observe that animals so high in the scale as the 

 Mammals that hybernate can, in the same way, carry on a 

 latent life for months without any nourishment, like Land-snails 

 or Amphibia; not only do they not suffer, but they actually 

 require this period of negative existence during their winter 

 sleep for the maintenance of their normal vitality. Por certain 

 reasons to be discussed presently, these animals during their 

 hybernation have been compared, and apparently with justice, 

 to the cold-blooded animals. 



The amount and kind of nourishment. — The amount of 

 nourishment required within a given time stands, as has 

 been observed, in the closest relation to the greater or less func- 



