680 URINE. 



in the liver, spleen, muscles and others, although only in small amounts. 

 Under pathological conditions, as in obstructed excretion, urea may 

 appear to a considerable extent in the animal fluids and tissues. 



The quantity of urea which is voided in twenty-four hours on a mixed 

 diet is in a grown man about 30 grams, in women somewhat less. While 

 children void less, the excretion relative to their body weight is greater 

 than in grown persons. The physiological significance of urea lies in 

 the fact that this body forms in man and carnivora, from a quantitative 

 standpoint, the most important nitrogenous end-product of the metabolism 

 of protein bodies. On this account the elimination of urea varies to a 

 great extent with the catabolism of the protein, and above all with the 

 quantity of absorbable proteins in the food ingested. The elimination 

 of urea is greatest after an exclusive meat diet, and lowest, indeed less 

 than during starvation, after the consumption of non-nitrogenous sub- 

 stances, since these diminish the metabolism of the proteins of the body. 



If the consumption of the proteins of the body is increased, then 

 the elimination of nitrogen is correspondingly increased. This is found to 

 be the case in fevers, after poisoning with arsenic, antimony, phosphorus, 

 and other protoplasmic poisons, and when there is a diminished supply 

 of oxygen as in severe and continuous dyspnoea, poisoning with carbon 

 monoxide, hemorrhage, etc. In these cases it used to be considered that 

 the rise in the excretion of nitrogen was due to an increased elimination 

 of urea, because no exact difference was made between the quantity 

 of urea and of total nitrogen in the urine. Recent researches have con- 

 clusively demonstrated the untrustworthiness of these observations. 

 Since PFLUGER and BORLAND have shown that 16 per cent of the total 

 nitrogen of the urine exists under physiological conditions in other com- 

 pounds, not urea, attention has been called to the relation of the dif- 

 ferent nitrogenous constituents of the urine to each other, and it has 

 been found, under pathological conditions, that this relation may vary 

 considerably, especially in regard to the urea. We have numerous 

 determinations by different investigators, 1 on the relation of the different 

 nitrogenous constituents to each other in the normal urine of adults. 



1 Pfluger and Bohland, Pfliiger's Arch., 38 and 43; Bohland, ibid., 43; Schultze, 

 ibid., 45; Camerer, Zeitschr. f. Biologic, 24, 27, and 28; Voges, Ueber die Mischung 

 der stickstoffhaltigen Bestandtheile im Harn. etc. (Inaug.-Diss. Berlin. 1892), cited 

 from Maly's Jahresber., 22; K. Morner and Sjoqvist, Skand. Arch. f. Physiol., 2. 

 See also Sjoqvist, Nord. Med. Arkiv., 1892, No. 36, and 1894, No. 10; Gumlich, Zeitschr. 

 f. physiol. Chem., 17; Bodtker, see Maly's Jahresber., 26; Folin, Amer. Journ. of 

 Physiol., 13; Osterberg and Wolff, Journ. of biol. Chem., 3; Haskins, ibid., 2; Bonze" 

 et Lambling, Journ. de Physiol. et de Path., 5; Bouchet, ibid., 14; Lambling et 

 Bouchet, Compt. rend. soc. biol., 71; Long and Gephart, Journ. Amer. Chem. 

 Soc., 34. 



