l82 NUTRITION, DIETETICS AND ANIMAL HEAT 



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 t^e 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 replace- 

 ment 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 (4^5) and of car- 

 bon about 281 grams (8^2). These are the amounts, there- 

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

 representing the proteid molecule in general, the formula, Ci2 

 HmOifflNisS. Then it is evident that an amount of proteid 

 food which would furnish the necessary 18 grams of nitro- 

 gen 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 system 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, particu- 

 larly the kidney a tax which is rendered unnecessary 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 nitro- 

 genous food alone, and life will be preserved indefinitely 

 perhaps, but the prediction would be warranted that in such 

 a case the person would probably die prematurely as a re- 

 sult of kidney or liver disease. 



Articles Which Will Supply the Necessary Amounts of 

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

 the average man needs daily about 120 grams of proteid, 90 

 grams of fat, and 320 grams of carbohydrate food, estimated 



