SPECIFIC-DYNAMIC EFFECT OF PROTEINS 531 



capable accordingly of maintaining the organism in equilib- 

 rium ; and taking the fasting energy requirement as 100, an 

 amount of energy equivalent to about 140 in the form of 

 protein is required to reestablish the caloric equilibrium. 

 Graham Lusk 33 expresses this in the following schema : 



Fasting requirement in potential energy = 100 calories. 

 One hundred and forty calories are given in the form of 

 meat protein : 



/ * v 



40 calories 100 calories 



= the amount of heat set = the potential energy, 

 free in the catabolism of available for cellular life, 

 the protein, available in- 

 stead of heat to be ob- 

 tained by chemical regula- 

 tion. 



With reference to Buhner's much debated idea that 

 protein in metabolism is split into a nitrogenous and a 

 nitrogen-free moiety, and that the energy obtained from 

 the first by oxidation is not available for the vital cellular 

 activities to the same degree as the energy present in the 

 other part, the author prefers to refrain from any detailed 

 comment, as the idea seems to him altogether hypothetical. 34 

 But it may be mentioned that recent very exact calorimetric 

 and gasometric experiments by Williams, Eiche and Graham 

 Lusk 35 seem to favor the idea, as after free meat feeding 

 a formation de novo of sugar from protein seemed to take 

 place (v. sup., p. 234 et seq.). Unquestionably the caloric 

 effect of meat feeding is sure to be influenced in a very 

 important degree by such a process. 



It might be supposed that, in reference to the question 

 upon precisely what the specific-dynamic effect of protein 



83 Graham Lusk : Ernahrung und Stoffwechsel, 2d ed., translated into Ger- 

 man by Leo Hess, pp. 141-148, 1910. 



84 Cf. A. Magnus-Levy, Handb. d. Pathol. d. Stoffw., 2d ed., 1, 226, 231, 1906. 



85 H. B. Williams, J. A. Riche and G. Lusk (Cornell Med. College), Jour, 

 of Biol. Chem., 12, 349, 1912. 



