Food and its Digestion. 



249 



combining with the tissues, produces greater waste, con- 

 sequently a larger supply is necessary principally of such 

 food as will rapidly produce carbonic acid. This explains 

 why so large an amount of animal and fatty food is con- 

 sumed by nations inhabiting cold regions, and why in our 

 own climate we can use so much more of these in the 

 winter season than in the summer, why the Greenlander 

 so enjoys the fat of the seal, the blubber and the train oil, 

 which become so disgusting to those inhabiting warmer cli- 

 mates. With these nations too, alchohol in all its various 

 forms (carbon hydrogen combinations), will be used with 

 greater freedom, being useful like fuel for combustion. 

 In the hot climates, where the air is more rarihed, conse- 

 quently less oxygen inspired in the same period of time, 

 a vegetable diet is largely used, and which though 

 abounding in sugar and starch, carbo-hydrates, it is more 

 slowly digested, consequently not so readily converted into 

 matter for combustion. 



The degree of bodily or mental exertion, influencing 

 the muscular and nervous textures, influences the kind 

 and the amount of food requisite. Where the time is 

 occupied in either kind of labor, more food will be re- 

 quired than where the time is passed in idleness. This 

 has been proven in a variety of ways : for example, com- 

 paring the dietaries of able-bodied men, like soldiers, with 

 that for prisoners it is found that an able-bodied man 

 will require from 31 to 38 ounces (2 lbs. 6 oz.), of dry 

 nutritious food daily — of fluids 52 ounces — over 3 pints. 

 In prisons somewhat less is needed, though here, reducing 

 the amount below 30 ounces daily, will induce scurvy. 



But the nutritious character of any substance, or its 

 value as an article of food, does not depend simply upon 

 its containing either one of these alimentary elements of 

 which we have been speaking in large amount, but upon 

 its containing them all mingled together, in just such 

 proportion as is requisite for the healthy nutrition of the 

 body. No chemical analysis can determine this propor- 



