THE NUCLEOPROTEIDS. 295 



that the amount of glycocoll in beef kidneys could be appreciably increased 

 by digesting them with uric acid. 1 It seems probable that the decom- 

 position of uric acid may result in the formation of glycocoll; but we, 

 nevertheless, wish to state that Wiener's investigation is not entirely con- 

 vincing, for his method of estimating the glycocoll was not an exact one, 

 and, above all, its production from other sources was not absolutely 

 excluded. As the proteins participate largely in the production of glycocoll, 

 it is necessarily difficult to estimate the amount of glycocoll originating 

 from the uric acid. 



Urine also contains oxalic acid: 



COOH 



COOH 



A part of this undoubtedly originates from the food. Another portion 

 is unquestionably produced in the tissues. The assumption has often 

 been made that oxalic acid may be a decomposition product of uric acid, 

 although no satisfactory proof has been presented to substantiate this 

 view. From a chemical standpoint such a formation of oxalic acid seems 

 perfectly possible. We know that uric acid can go over into alloxan, 

 parabanic acid, oxaluric acid, and finally into oxalic acid. It is impossible 

 to say anything further about a source of the oxalic acid which does not 

 come from the food. 



Allantoine has often been regarded as a decomposition product in the 

 hypothetical formation of oxalic acid from uric acid. It was first found 

 in the allantoic fluid, and later recognized by Wohler 2 as a normal con- 

 stituent of the urine of suckling calves. Gusserow 3 has recently isolated 

 it from the urine of new-born children. Allantoine is also found in the urine 

 of various full-grown mammalia; for instance, dogs, cats, and rabbits. ' 



Allantoine is the diuride of glyoxylic acid. It can easily be obtained 

 by melting glyoxylic acid with urea: 



COH / NH2 / NH-OH NH 



| + 2 CO = CO 



COOH \ X NH 



\ 



CO + 2 H 2 O 



Glyoxylic acid Urea Allantoine 



The question of the origin of allantoine has been answered in various 

 ways. It is generally believed to be related to the purine bodies. This 

 assumption was strengthened by the discoveries of Salkowski 4 and Min- 



1 Arch, exper. Path. Pharm. 43, 375 (1899). 



2 Ann. 26, 244 (1838); 70, 229 (1849); 88, 100 (1853). 



3 Arch. Gyn. 3, 270 (1872). G. Pouchet: Beitrige zur Kenntnis der Extraktivstoffe 

 des Urins, Paris, 1880 (pp. 28 and 37). 



4 E. Salkowski: Zent. Med. Wiss. 36, No. 53, 929 (1898). 



