22 THE AMOUNT OF OXYGEN 



In cold and temperate climates, the air, which 

 incessantly strives to consume the body, urges man 

 to laborious efforts in order to furnish the means of 

 resistance to its action, while, in hot climates, the 

 necessity of labour to provide food is far less urgent. 



Our clothing is merely an equivalent for a certain 

 amount of food. The more warmly we are clothed 

 the less urgent becomes the appetite for food, be- 

 cause the loss of heat by cooling, and consequently 

 the amount of heat to be supplied by the food, is 

 diminished. 



If we were to go naked, like certain savage 

 tribes, or if in hunting or fishing we were exposed 

 to the same degree of cold as the Samoyedes, w^e 

 should be able with ease to consume 10 lbs. of flesh, 

 and perhaps a dozen of tallow candles into the bar- 

 gain, daily, as warmly clad travellers have related 

 with astonishment of these people. We should then 

 also be able to take the same quantity of brandy or 

 train oil without bad effects, because the carbon and 

 hydrogen of these substances would only suffice to 

 keep up the equilibrium between the external tem- 

 perature and that of our bodies. 



According to the preceding expositions, the quan- 

 tity of food is regulated by the number of resj^ira- 

 tions, by the temperature of the air, and by the 

 amount of heat given off to the surrounding me- 

 dium. 



No isolated fact, apparently opposed to this state- 

 ment, can affect the truth of this natural law. 



