ELIMINATION OF URIC ACID. 665 



in large quantities in " chalk-stones," certain urinary calculi, and in 

 guano. It has also been detected in the urine of insects and certain 

 snails, as also in the wings (which it colors white) of certain butterflies 

 (HOPKINS 1 ). 



The amount of uric acid eliminated with human urine is subject to 

 considerable individual variation, but amounts on an average to 0.7 

 gram per day on a mixed diet. The ratio of uric acid to urea varies con- 

 siderably with a mixed diet, but is on an .average 1 : 50-1 : 70. In new- 

 born infants and in the first days of life the elimination of uric acid is 

 relatively increased, and the relation between uric acid and urea has been 

 found to be 1:6.42-17.1. 



We used to ascribe an increasing action upon the elimination of uric 

 acid to protein food, but the investigations of HIRSCHFELD, ROSEN- 

 FELD and ORGLER, SIVEN, Bum AN and SnuR, 2 and many others have 

 positively proven that a diet rich in protein does not itself increase the 

 elimination of uric acid, but only according to the amount of nucleins 

 or purine bodies contained therein. The common assumption that the 

 elimination of uric acid is smaller with a vegetable diet than with an ani- 

 mal diet, when the quantity may be 2 grams or more per twenty-four 

 hours, is explained by this. 3 



Still a purine-free diet is not without some influence upon the elimina- 

 tion of uric acid, as the quantity of uric acid eliminated with a purine-free 

 diet is considerably greater than in starvation. HIRSCHSTEIN explains this 

 by the formation of secretions containing purines due to the digestion, an 

 explanation which BRUGSCH and SCHITTENHELM 4 do not accept. Work 

 and rest do not seem to have any special influence upon the uric acid 

 elimination, although according to the confirmed statement of SIVEN and 

 LEATHES 5 the elimination in the night is less than in the morning hours. 



The reports in regard to the influence of other circumstances, as well 

 as of different substances, on the elimination of uric acid are diverse. 

 This is in part due to the fact that the earlier investigators used an 

 inaccurate method (HEINTZ) , and also that the extent of uric-acid elimina- 

 tion is dependent in the first place upon the individuality. Thus the 

 investigators are not in accord in regard to the action of drinking- 



1 Philos. Trans. Roy. Soc., 186, B, 661. 



2 See the extensive review of the literature in Wiener, " Die Harnsaure," in Ergeb- 

 nisse der Physiologic, 1, Abt. 1, 1902. 



3 J. Ranke, Beobachtungeri und Versuche iiber die Ausscheidung der Harnsaure, 

 etc. (Miinchen, 1858); Mares, Centralbl. f. d. med. Wissensch., 1888; Horbaczewski, 

 Wien. Sitzungsber., 100, Abt. 3, 1891. In regard to the action of various diets the 

 reader is referred to the above-cited authors, and especially to A. Hermann, Arch, f . klin. 

 Med., 43,.and Camerer, Zeitschr. f. Biologic, 33, and Folin, Amer. Journ. of Physiol., 13. 



4 Zeitschr. f. exp. Path. u. Therap., 4; Hirschstein, Arch. f. exp. Path. u. Pharm., 57. 



5 Siven, Skand. Arch. f. Physiol., 11; Leathes, Journ. of Physiol, 35. 



