THE BALANCE OF NUTRITION 241 



According to the conception of the schematic body (280), 

 these figures show that energy to the extent of 608 Cals. was 

 stored up in the body as the chemical energy of either protein, 

 fat or glycogen. Assuming that there was no change in the 

 glycogen content of the animal, the nitrogen and carbon balance 

 showed a computed storage of 66.6 grams of protein and 15.2 

 grams of fat (294). The average chemical energy of protein is 

 5.7 Cals. per gram and that of fat 9.5 Cals. per gram. The 

 amounts of energy stored up in the fat and protein gained by the 

 steer can therefore be computed as follows : 



In protein 5.7 Cals. X 66.6 = 380 Cals. 

 In fat 9.5 Cals. X 15.2 = 144 Cals. 

 Total 524 Cals. 



Found from energy balance 608 Cals. 

 Difference 84 Cals. 



It thus appears that in this experiment the gain of energy 

 found by a direct determination of the energy balance and that 

 computed from the balance of nitrogen and carbon agreed 

 within 84 Cals., or 0.3 per cent of the total amount of energy 

 involved. It is evident that determinations of the nitrogen 

 and carbon balance on the one hand and of the energy balance 

 on the other may serve as a mutual check, and also that the 

 heat production of an animal may be computed quite accurately 

 from determinations of the nitrogen and carbon balances (in- 

 direct calorimetry.) 



5. SIGNIFICANCE OF RESULTS 



Studies of the balance of nutrition have played a very promi- 

 nent role in both physiological and agricultural investigation. 

 Having considered in the foregoing pages the general methods 

 of the balance experiment, a brief consideration of the signifi- 

 cance of the results obtained by their use as compared with those 

 reached by other methods seems called for. 



330. Comparison with metabolism investigations. The 

 results of experiments like the one with a steer used as an 

 illustration in previous paragraphs show, within the limits of 

 experimental error, the loss or the storage of chemical energy 



