1 82 NUTRITION, DIETETICS AND ANIMAL HEAT 



requirements of the system. Moreover, the air we breathe and 

 the water we drink furnish an ample supply of hydrogen and 

 oxygen when to this supply is added the quota of these elements 

 contained in the necessary quantities of other aliments. So, 

 therefore, if we fix upon a diet which will furnish the requisite 

 amounts of carbon and nitrogen no attention need be paid to 

 the other elements. The supply of the others may be said to 

 regulate itself if the supply of carbon and nitrogen be regulated. 



The object, then, of food may be said to be the replacement 

 of carbon and nitrogen the carbon and nitrogen in the excreta. 

 Of these two elements, carbohydrates and fats will furnish only 

 carbon; proteid food will furnish both. 



Amount of C and N Necessary. It is found that the daily 

 discharge of nitrogen is about 18 grams (4i3) an< i of carbon 

 about 281 grams (8J). These are the amounts, therefore, 

 which must be supplied by food. We may accept, as represent- 

 ing the proteid molecule in general, the formula, C 72 H 112 O 22 N 18 S. 

 Then it is evident that an amount of proteid food which would 

 furnish the necessary 18 grams of nitrogen would furnish only 72 

 grams of carbon only about one-fourth enough. If, now, the 

 proteid food be increased to supply 281 grams of carbon, the sys- 

 tem will have to handle four times as much nitrogen as it needs; 

 and this is a tax to the digestive apparatus and the excretory 

 organs, particularly the kidney a tax which is. rendered unnec- 

 essary by the availability of the carbohydrates and fats as food. 

 These contain abundance of carbon, and it is far better to eat 

 only enough proteid food to supply the 18 grams of nitrogen, and 

 make up the deficit of carbon with non-nitrogenized articles of 

 diet. One can supply all the demands by eating nitrogenous food 

 alone, and life will be preserved indefinitely perhaps, but the pre- 

 diction would be warranted that in such a case the person would 

 probably die prematurely as a result of kidney or liver disease. 



Articles Which will Supply the Necessary Amounts of 

 C and N. The conclusion (modified) of Moleschott is that 



