118 VARIOUS FOOD-PLANTS 



enough to yield about 1,000 Calories or 805,600 kilogrammeters of 

 energy, which has been found-to be approximately tlie amount ex- 

 pended in 24 hours. If at first sight this seems to be an exaggerated 

 estimate of the energy given out, it should be borne in mind that a 

 very large share goes to keep up the warmth of the Ijody; while of 

 the remainder wdiich is transformed into mechanical activity, a 

 considerable proportion is used up in the muscular movements 

 of the digestive organs, in breathing some 23,000 times, and in mak- 

 ing more than 600,000 heart-beats, thus leaving only about one 

 third of the whole available for locomotion and external work. 



The main point which here concerns us regarding the 

 make-up of a proper daily ration is the relative proportion 

 of nutrients rather than their absolute amount. On the basis 

 of the figures given, it may be stated roughly and in a general 

 way that 1 part proteid, 1 part fat, and 6 parts carbohydrate, 

 would ordinarily meet the daily needs of an average person, 

 or in other words that one's food should be about | proteid, 

 i fat and f carbohydrate. In the rations recommended it 

 is assumed that the foods chosen are easily digestible; for 

 it is not what we eat but what we digest that nourishes us. 

 For students and other brain-workers digestibility is of es- 

 pecial importance since their largely sedentary life leaves 

 them but little surplus energy to spare for unnecessary 

 digestive work. 



A glance at the chemical chart (Fig. 120) will show that 

 many vegetable foods do not have their nutritive constit- 

 uents in anything like the standard proportion. This means 

 that if a man were to obtain all his nourishment from such 

 foods, he would have to eat too much of one ingredient 

 (generally a carbohydrate) in order to get enough of another. 

 When it is remembered that the dry substance of meats, fish, 

 eggs, and other such foods of animal origin, consists almost 

 entirely of proteids and fats, we see that here also there is a 

 similar disproportion, although in another direction. Since, 

 however, the constituents which are deficient on the one side, 

 are in excess on the other, a mixed diet combining animal 

 with vegetable foods, is most likely to be well-balanced. 



From this point of view it is interesting to notice how 

 generally the instincts of mankind have led them to prefer 

 combinations of food wherein the comjoonents supplement 



