THE TOTAL EXCHANGES OF THE BODY 693 



carbon and nitrogen reappearing in the excreta serve as an index 

 of the amount of metabolism of the food-stuffs which had occurred 

 during the two days. In order to supply the energy requirements 

 of the body during the time of the experiment, 498 grm. of carbo- 

 hydrate, 59 grm. of alcohol, and 138 grm. of fat had been completely 



TOTAL INCOME 



TOTAL OUTPUT 



oxidised. The amount of protein used up during this time can be 

 obtained by multiplying the nitrogen of the urine plus 1 grm. of 

 nitrogen of the faeces by the factor 6'25, and is found to amount to 

 271-9 grm. 



THE ENERGY BALANCE-SHEET OF THE BODY 

 The energy income of the body is measured by the potential 

 energy of the food-stuffs, i.e. the amount of energy which can be 

 evolved, either as heat, work, or in any other form, by the oxida- 

 tion of the food-stuffs to the end-products which occur in the 

 body. Since it is convenient to have a uniform method of 



