THE UTILIZATION OF FOOD IN ANIMALS 337 



securing it from localities where it was more abundant. 

 Modern transportation systems have changed conditions so 

 that in times of peace a famine can hardly occur except in 

 an undeveloped country. 



Sometimes the cost of food is so great that many people 

 cannot afford to buy enough of it. The population of the 

 United States has been increasing more rapidly than the pro- 

 duction of food, and this, together with the Great War and 

 other causes, results in prices exceeding any previously known. 



342. The purpose of food. Many people do not consider 

 why they take food into their bodies. Doubtless, if asked to 

 give an immediate answer to the question as to why they 

 eat, many would say that it is to satisfy hunger. In a way 

 such an answer would be correct, but it would be superficial. 

 Indeed, if that were the only reason, it would not be worth 

 while to expend all the time and trouble that we do in eat- 

 ing. One may discipline himself in a few days, as has often 

 been done by men who have fasted, to such an extent that 

 hunger no longer troubles him seriously. If this were con- 

 tinued, death would ensue, though the person, it is said, might 

 not be conscious of hunger for some time prior to his death. 



We eat in order that growth may take place, in order that 

 waste protoplasm may be replenished above all, in order 

 that energy may be brought into the body and used in doing its 

 work, whether it is the beating of the heart or riding a bicycle. 

 Growth and replenishment of protoplasm and the release and 

 use of energy are, therefore, the real purposes of nutrition. 



343. The human body a machine. The human body is 

 often compared to a machine because it can do work. It is 

 infinitely more wonderful than any automobile, however, not 

 only because it can take itself uphill but because it grows 

 from a small machine to a big one and keeps itself in repair. 

 All that most of us have to do is to feed the machine the 

 proper kind of food and observe the rules of hygiene, and 

 the machine takes care of itself. We have little respect for 



