716 URINE. 



f^OOTT 

 Oxalic Acid, C2H2O4, or , occurs under physiological conditions 



in very small amounts in the urine, about 0.02 gram in twenty-four hours 

 (FuRBRiNGER l ). According to the generally accepted view it exists in 

 the urine as calcium oxalate, which is kept in solution by the acid phos- 

 phates present. Calcium oxalate is a frequent constituent of uninary 

 sediments, and also occurs in certain urinary calculi. 



The origin of the oxalic acid in the urine is not well known. Oxalic 

 acid when administered is eliminated unchanged, at least in part, by 

 the urine; 2 and as many vegetables and fruits, such as cabbage, spinach, 

 asparagus, sorrel, apples, grapes, etc., contain oxalic acid, it is possible 

 that a part of the oxalic acid of the urine originates directly from the 

 food. That oxalic acid may be formed in the animal body as a metabolic 

 product from proteins or fats follows from the observations of MILLS 

 and LUTHJE and others, who found that in dogs on an exclusively meat 

 and fat diet, as also in starvation, oxalic acid was eliminated by the urine. 

 The oxalic acid which is eliminated in increased quantity with a diminished 

 oxygen supply and an increased protein catabolism, as found by REALE 

 and BOERI, and also by TERRAY, is supposed to be derived partly from 

 the greater destruction of proteins. Pure protein does not, accord- 

 ing to SALKOWSKI and WEGRZYNOWSKI 3 increase the quantity of oxalic 

 acid eliminated; on the contrary, after meat feeding the amount of this 

 acid is increased, due in part to the meat containing oxalic acid (SAL- 

 KOWSKI). Gelatin and gelatin-yielding tissues seem to increase the 

 excretion of oxalic acid, and the same is also true for fats or at least 

 glycerin (WEGRZYNOWSKI). After feeding nucleins no constant increase 

 in the elimination of oxalic acid has been observed. The statements 

 as to the action of carbohydrates are contradictory. The production of 

 oxalic acid due to an incomplete combustion of the carbohydrates has also 

 been suggested, and the work of HILDEBRANDT and P. MAYER seems to 

 indicate this under abnormal conditions. According to DAKiN, 4 in rabbits 

 an increased elimination of oxalic acid occurs after the introduction of 

 glycollic or glyoxylic acids, and the oxalic acid seems in many cases to 

 be an intermediary product of metabolism, which is further burnt. We 

 cannot exclude the possibility of the formation of oxalic acid in the 

 oxidation of uric acid in the animal body, yet we have no positive proof 



1 Deutsch. Arch, f . klin. Med., 18. See also Dunlop, Journ. Path, and Bacteriol., 3. 



2 In regard to the behavior of oxalic acid in the animal body, see page 773. 

 3 Reale and Boeri, Wien. med. Wochenschr., 1895; Terray, Pfluger's Arch., 65; 



Salkowski, Berl. klin. Wochenschr., 1900; Wegrzynowski. Zeitschr. f. physiol. Chem., 

 83 which contains the literature. 

 4 Journ. of biol. Chem., 3, 57. 



