NITROGEN ELIMINATION. NITROGEN DEFICIT. 881 



fluids. It may not vary in different individuals only, but also in the same 

 individual after more or less active secretion and absorption. In the 

 attempts made to determine this part of the nitrogen of the excrement 

 it has been found that in man, on non-nitrogenous or nearly nitrogen- 

 free food, it amounts in round numbers to somewhat less than 1 gram 

 per twenty-four hours (RIEDER, RUBNER). Even with such food the 

 absolute quantity of nitrogen eliminated by the feces increases with 

 the quantity of food because of the accelerated digestion (TsuBOi 1 ), 

 and is greater than in starvation. MtiLLER 2 found in his observations 

 on the faster CETTI that only 0.2 gram nitrogen was derived from the 

 intestinal canal. 



The quantity of nitrogen which leaves the body under normal circum- 

 stances by means of the hair and nails, with the scaling off of the skin, 

 and with the perspiration cannot be accurately determined. It is 

 nevertheless so small that it may be ignored. Only in profuse sweating 

 need the elimination by this channel be taken into consideration. 



The view was formerly held that in man and carnivora an elimination 

 of gaseous nitrogen took place through the skin and lungs, and because of 

 this, on comparing the nitrogen of the food with that of the urine and 

 feces, a nitrogen deficit occurred in the visible elimination. 



This question has been the subject of much discussion and of numerous 

 investigations, the most recent by KROGH and OppENHEiMER. 3 These 

 researches have shown that the above assumption is unfounded, and 

 moreover several authorities, especially PETTENKOFER and VOIT, and 

 GRUBER, 4 have shown by experiments on man and animals that with 

 the proper quantity and quality of food the body can be brought into 

 nitrogenous equilibrium, in which the quantity of nitrogen voided with 

 the urine and feces is equal or nearly equal to the quantity contained in 

 the food. Undoubtedly we must admit, with VOIT, that a deficit of nitro- 

 gen does not exist, or it is so insignificant that in experiments upon 

 metabolism it need not be considered. Ordinarily, in investigations on 

 the catabolism of proteins in the body, it is only necessary to consider the 

 nitrogen of the urine and feces, but it must be remarked that the nitrogen 

 of the urine is a measure of the extent of the catabolism of the proteins 



1 Rieder, Zeitschr. f. Biologie, 20; Rubner, ibid., 15; Tsuboi, ibid., 35. 



2 Berlin, klin. Wochenschr., 1887. 



3 See Regnault and Reiset, Annal. d. chem. et phys. (3), 26, and Annal. d. Chem. 

 u. Pharm., 73; Seegen and Nowak, Wien. Sitzungsber., 71, and Pfliiger's Arch., 25; 

 Pettenkofer and Voit, Zeitschr. f. Biologie, 16; Leo, Pfliiger's Arch., 26; Krogh, 

 Skand. Arch. f. Physiol., 18, and Wien. Sitz. Ber., 115, III; Oppenheimer, Bioch. 

 Zeitschr., 4. 



4 Pettenkofer and Voit, hi Herrman's Handbuch, 6, Thl. 1; Griiber, Zeitschr. f. 

 Biologie, 16 and 19. 



