30 August Krogh and Marie Krogh. 



hours nitrogen values for the urine are therefore reckoned from 12 

 md. to 12 md. in exp. I, and from 2 p. m. — 2 p. m. in exp. II, III 

 and IV. It is of course not absolutely certain, though in our opinion 

 extremely probable, that the absorption of the nitrogenous food is 

 practically completed within the 24 hours, and when that is the case 

 the figures show a very considerable retention of nitrogen within the 

 organism in those subjects who had had but little nitrogenous food 

 for at least two days, namely 



N in meat N in urine Balance 



gr. gr. gr. 



82 53 29 35 "/o 



73 50 23 32 «lo 



50 29 21 42 0|o 



When nitrogen amounting to 20 — 30 gr. is retained (beyond 

 24 hours) there can in our opinion be very little doubt that it must 

 be retained chiefly in the form of protein though the extract N is un- 

 doubtedly increased also. We think it highly improbable that the 

 concentration of urea and allied substances in the body could rise 

 sufficiently to explain a retention of the magnitude observed by us. 



When large amounts of protein can be stored there is no reason 

 why the catabolism should not take place according to the energy 

 requirements of the body. We look upon the specific dynamic action 

 of protein as a consequence of its being incompletely catabolized 

 (deaminized) immediately after absorption and in cells which do not 

 require and therefore cannot utilize the energy liberated in the process. 

 When protein is stored as such it may be carried to cells which are 

 able to utilize the energy liberated by deaminization and use the pro- 

 tein as an equivalent of any other source of energy, and if that is so 

 we must expect that the specific dynamic action of the stored material 

 should disappear, or at all events become greatly reduced. As will 

 be shown below we have in our experiments found a remarkably low 

 specific dynamic action of the protein. 



The Urine Excretion. 



The excretion of nitrogen in the urine has been followed from 

 hour to hour in order to compare the nitrogen metabolism with the 

 corresponding respiratory exchange. The curves obtained indicate, 

 however, very distinctly that the excretion of N does not run parallel 

 to the metabolism and probably not even to the formation of urea, 

 but is strongly influenced by various other factors. This has been 

 observed before by Neumann ^ who found that consumption of large 

 quantities of water will produce a considerable increase in the ex- 

 cretion of nitrogen. Frank and Trommsdorff ^ lay great stress upon 



1 Arch. f. Hygiene, Bd. 36, 1899. 

 * Zeitschr. f. Biol., Bd. 43, 1902. 



