THE CHEMIST/,' Y OF THE ANIMAL BODY. 557 



10,000 liters of urine 1 has shown the presence of 10.11 grams of xanthin, 

 8.5 grams of hypoxanthin, and 3.54 grams of adenin. 



Xanthin fed to birds is converted into uric acid. In birds the formation of uric acid 

 depends on a synthetic union of ammonia and lactic acid in the liver, since on extirpation 

 of the liver the last two substances appear in the urine in amounts proportional to the 

 normally formed uric acid (see p. 546). 



The literature on the subject of gout is enormous. It is sufficient to re- 

 mark here that it is not even known whether gout is due to an increased for- 

 mation or an increased retention of uric acid. The amount of uric acid in the 

 blood is certainly increased. The normal amount of uric acid in the daily 

 urine is put at 0.7 gram, that of the purin bases at 0.1 325, 2 although this 

 latter may be too high on account of the presence of the bases derived from 

 tea and coffee. The amount of the bases may be quadrupled in leucocy- 

 thsemia. 3 



Diatomic Dibasic Acids, C n H 2n _ 2 4 . 



COOH 



Oxalic Acid, | . — This is found as calcium oxalate in the urine, and 



COOH 

 is present in most plants. It is a product of boiling proteid with barium 

 hydrate. It may be obtained synthetically by heating sodium formate : 



COONa 

 2HCOONa=| +2H. 



COONa 



Oxalic acid and its alkaline salts are very soluble in water. Its calcium salts 

 are insoluble in water and dilute acetic acid, but are soluble in the acid phos- 

 phates of the urine. 



According to Lommel, 4 oxalic acid is a product of metabolism, and is 

 not produced proportionally to proteid destroyed, but occurs in increased 

 amounts in the urine when nucleins (thymus) and gelatin arc fed. The 

 occurrence of oxalic acid in the urine after feeding nucleins is significant 

 in virtue of its possible origin from uric acid (see Uric Acid, p. 55 I ). Stones 

 in the bladder are sometimes composed of calcium oxalate, as are also urinary 

 sediments when formed in consequence of ammoniacal fermentation. 



Succinic Acid, HOOC.C 2 H 4 .COOH— This has been detected in the 

 spleen, thymus, thyroid, in echinococcus fluid, and often in hydrocele fluid. It 

 is a product of alcoholic fermentation, and of proteid putrefaction. It is often 

 found in plants. 



Amido-succinic Acid, or Aspartic Acid, HOOC.C 2 H 3 NH,.CXX)I I . 

 This is a product of boiling proteid with acid or alkalies, and it is also formed 

 under the influence of trypsin in proteid digestion. 



1 Kruger and Salomon: Zeitschrift fur physiologische Chemie, L898, Bd. 26, B. 850. 



2 Kriigerand Wulff: Ibid., 1895, Bd. 20, S. 184. 3 Boudzynslri and < tottlieb, <>r- at., 8. 132. 

 4 Deutsches ArcMvfur klinische Medizin, 1899, Bd. til'., S. 599. 



