NORMAL PROCESSES OF ENERGY METABOLISM 567 



TABLE 8 



HEAT VALUE OF OXYGEN AND CARBON DIOXID FOR DIFFERENT NON-PROTEIN RESPIRATORY 



QUOTIENTS 



(7) Read off heat value of Non-Prot. R. Q. from table. 



(8) Multiply by liters of Non-Prot. O 2 . 



(9) Multiply N of Urine by its heat value (26.51 Cal. for meat diet). 

 (10) Add 8 and 9 for total heat production. 



B. Direct Calorimetry 



Without the disintegration of organic substances accompanied by a 

 diminution of potential energy life is impossible. One of the forms which 

 the liberated energy inevitably takes is heat, and in the resting organism, 

 i. e., not transferring energy in the form of mechanical work to other ob- 

 jects, all of the energy finally takes this form. The quantity of heat, there- 

 fore, becomes a measure of vitality. 



We have seen that this measure can be applied in an indirect way by 

 measuring the potential energy of the foodstuffs or by assigning a heat 

 equivalent to a unit of oxygen absorbed. But this method is based upon 

 certain assumptions which are always open to debate, namely, the assump- 

 tion that specific chemical changes are always accompanied by the same 

 transformations of energy and the assumption that the law of the con- 

 servation of energy applies to all chemical transformations in the animal 

 body. Most authorities are agreed that for these reasons the direct meas- 

 urement of heat generated in the living organism is at least more authori- 

 tative even though the accomplishment of this end may be beset with great 

 difficulties. Krogh(c) states that "With the recent advances in calorimetric 

 methods due to Atwater and Benedict, Rubner and especially A. V. Hill, 



