AMOUNT OF OXYGEN ABSORBED. 17 



oxygen inspired and of carbonic acid expired, must 

 therefore vary with the height of the barometer. 



The oxygen taken into the system is given out 

 again in the same forms, whether in summer or 

 in winter; hence we expire more carbon in cold 

 weather, and when the barometer is high, than we 

 do in warm weather ; and we must consume more 

 or less carbon in our food in the same proportion ; 

 in Sweden more than in Sicily ; and in our more 

 temperate climate a full eighth more in winter 

 than in summer. 



Even when we consume equal weights of food in 

 cold and warm countries, infinite wisdom has so 

 arranged, that the articles of food in different cli- 

 mates are most unequal in the proportion of carbon 

 they contain. The fruits on which the natives of 

 the south prefer to feed do not in the fresh state 

 contain more than 12 per cent, of carbon, while the 

 bacon and train oil used by the inhabitants of the 

 arctic regions contain from 66 to 8t) per cent, of 

 carbon. 



It is no difficult matter, in warm climates, to 

 study moderation in eating, and men can bear hun- 

 ger for a long time under the equator ; but cold 

 and hunger united very soon exhaust the body. 



The mutual action between the elements of the 

 food and the oxygen conveyed by the circulation 

 of the blood to every part of the body is THE SOURCE 



OF ANIMAL HEAT. 



