1 92 A RESPIRATION CALORIMETER. 



It may happen that the body will increase its store of one material 

 while drawing upon that of another. Thus the figures for the experi- 

 ment under discussion (Table 12) show a gain of glycogen and fat at 

 the same time with a loss of protein in the body. Under these circum- 

 stances, the quantity of energy from body material that is to be added 

 to the available energy of food is the difference between the energy of 

 material lost and that of material gained. 



CALCULATIONS OF ENERGY OF BODY MATERIAL GAINED AND LOST. 



Returning now to the summary of intake and output of energy in 

 Table 15, the total energy of body material gained or lost, as given 

 in column (/$) , is the algebraic sum of the quantities in columns (>) , 

 (/), and (g}. These latter quantities are calculated from the amounts 

 of body material gained or lost, as shown in Table 12, by use of factors 

 for the heats of combustion per gram of body materials. The factor 

 for protein, 5.65 calories per gram, is that for fat-free muscular tissue 

 from which the non-proteid nitrogenous compounds have not been 

 removed. The factor for fat, 9.54 calories per gram, is the average of 

 the results of several determinations of the heat of combustion of fat 

 from the human body; and the factor for glycogen, 4.19 calories per 

 gram, is likewise the result determined by actual combustion of that 

 material. Applying these factors to the amounts of body material 

 gained or lost, and adding (algebraically) the results, gives the total 

 amount of energy from body material, as illustrated by the following 

 computations for December 20 : 



Protein, 29.16 grams X 5.65 = 165 calories. 

 Fat, + 33.65 grams X 9-54 =- + 3 2 calories. 



Glycogen, + 17.34 grams X 4.19 = + 73 calories. 



Total energy from body material + 229 calories. 



The minus sign in column (^) indicates that the body has lost the 

 energy from the amount potential in its previously stored material, 

 while the plus sign in columns (/) and (g~) indicates that the energy 

 was potential in body material stored. The total amount of energy 

 derived from the body material that was utilized, shown in column (/z), 

 is therefore the difference between the amount lost and the amount 

 stored, or, in other words, the algebraic sum of the quantities in col- 

 umns (*), (/), and (). 



The figures in column (z) represent the estimated amounts of energy 

 of the material oxidized in the body. They are the difference between 

 the quantities in column (d), the available energy of the food, and those 

 in column (A), the energy from the body material stored. Since the 



