136 URINARY BASES 



Urinary Rest-nitrogen. If the nitrogen of the various 

 known urinary constituents for a given specimen be added 

 together and the total compared with the determined total 

 nitrogen, will any noticeable difference be found? It has 

 been shown that this actually is the case. By far the major 

 portion of the nitrogen, estimated as from 87 to 95 per cent, 

 of the total nitrogen ordinarily and in states of full diet, 49 is 

 referable in man and the mammals to urea. After calculat- 

 ing the fractions referable to uric acid, the purin bases and 

 creatinin, hippuric acid and ammonia, there still remains a 

 nitrogen rest which in human urine has been estimated at 

 from 2.5 to 8.5 per cent, by Donze and Lambling, 50 at about 

 5 per cent, by Folin, and 11 per cent, of the total nitrogen by 

 Maillard. These figures are changed as soon as the diet 

 becomes abnormal, the urea varying especially, falling, 

 particularly where opportunity for an acidosis occurs, with 

 corresponding increase in the ammonia, 0. Folin observed a 

 fall of the urea nitrogen to 60 per cent, of the total nitrogen 

 in as full as possible restriction of proteid metabolism by 

 means of a starch-cream diet. But even this is probably far 

 from the lowest limit which may be met. In an insane 

 patient, who took almost no food, Folin found only 15 per 

 cent, of the total nitrogen represented by the urea, and 40 per 

 cent, as ammonia ; 51 one would hesitate to give credence to 

 these figures if they were not published by one who is a 

 master of the technique of urinary analysis. It should be 

 remembered in this connection that similar perverse metab- 

 olism proportions have been observed in the hibernating 

 marmot (v. supra., p. 117), and have been described as an 

 enormous increase in the aminoacids at the expense of the 

 urea. 



*Cf. B. Schondorff, Pfliiger's Arch., 117, 275, 1907. 



60 G. Donz6 and E. Lambling, Jour, de Physiol., 5, 225, 1903; 0. Folin, 

 Amer. Jour, of Physiol., 13, 45, 1905; L. C. Maillard, Jour, de Physiol., 10, 

 1017, 1908. 



" O. Folin, 1. c. 



