AMOUNT OF FOOD REQUIRED. 715 



at which the body is capable of maintaining itself 

 at the natural standard, the caloric obtained by 

 respiration is not carried off, as at lower tem- 

 peratures, but accumulates in the system, pro- 

 ducing a disagreeable sensation of preternatural 

 warmth, the tendency of which is to diminish the 

 action of the lungs, and the generation of caloric. 

 By means of this admirable instinct, founded in 

 the natural aversion to pain, whether from exces- 

 sive heat or cold, men and other animals are 

 prompted to accommodate the amount of respira- 

 tion to the wants of the system, in different cli- 

 mates and seasons. 



But it is not only respiration that is from 30 to 

 38 per cent, less in tropical than in warm and 

 temperate climates, like those of Greece and 

 Italy, France and England ; for I have proved 

 that secretion, nutrition, or the formative process 

 by which the composition and vitality of the body 

 are maintained, depend on the transition of calo- 

 ric from arterial blood to the solids. It is there- 

 fore evident that the aggregate forces of life must 

 be diminished in proportion as the temperature of 

 the solids approximates that of the arterial blood.* 



* But as in the hottest climates the atmosphere is seldom 

 above the natural temperature of birds, it is obvious that in them 

 the process of nutrition, and the general powers of life, are much 

 less impaired than in the active mammalia ; and less in most of the 

 latter, such as the dog, wolf, fox, sheep, ox, horse, deer, hog, &c. 

 than in man, whose average temperature is several degrees lower. 

 Hence it is, that warm and hot climates are more favourable to 



