680 URINE. 



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

 phates present. Calcium oxalate is a frequent constituent of urinary 

 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; 1 and as many vegetables and fruits, such as cabbage, spinach, 

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

 that a part ol 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 LiiTHJE, 2 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, according 

 to SALKowsKi, 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 (SALKOWSKI). Gelatin and 

 gelatin-yielding tissues seem to increase the excretion of oxalic acid, 

 which stands in accord with the observations of KUTSCHER and SCHENCK 4 

 that on the oxidation of gelatin oxamic acid is produced from the glyco- 

 coll and this then readily decomposes into ammonia and oxalic acid. 

 After feeding nucleins no constant increase in the elimination of oxalic 

 acid has been observed. 5 The production of oxalic acid due to an incom- 

 plete combustion of the carbohydrates has also been suggested. The 

 work of HILDEBRANDT and P. MAYER seems to indicate this under abnor- 

 mal conditions. In alimentary glycosuria or diabetes LUZZATO 6 could 

 not observe any rise in the elimination of oxalic acid. According to 

 DAKIN/ in rabbits an increased elimination of oxalic acid occurs after 

 the introduction of glycollic or glyoxylic acids, and the oxalic acid seems 

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

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



1 In regard to the behavior of oxalic acid in the animal body, see page 733. 



2 Mills, Virchow's Arch., 99; Liithje, Zeitschr. f. klin. Med., 35. 



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

 Salkowski, Berl. klin. Wochenschr., 1900. 



4 Zeitschr. f. physiol. Chem., 43. 



5 See Stradomsky, Virchow's Arch., 163; Mohr and Solomon, Deutsch. Arch. f. 

 klin. Med., 70; Salkowski, 1. c. 



6 Hildebrandt, Zeitschr. f. physiol. Chem., 35; P. Mayer, Zeitschr. f. klin. Med., 47; 

 Luzzato, Salkowski's Festschrift, 1904. 



7 Journ. of Biol. Chem., 3, 57. 



