THE NUCLEOPROTEIDS. 289 



A part of the nucleic acid of the food is undoubtedly decomposed by 

 bacteria in the intestines. Purine bases are present in the faeces. 1 Martin 

 Kriiger and Schittenhelm 2 have shown that only a small part of the purine 

 bases in the faeces could originate in this manner. It has been found that 

 the quantitive distribution of the various purine bases in the faeces corre- 

 sponds very closely to that in the different organs, and that the main source 

 of supply is undoubtedly the degenerating intestinal epithelium and dead 

 bacteria. Only small amounts of bases are introduced into the intestines 

 by means of the pancreatic and intestinal juices. 



Until recently, we knew but very little about the relation of the nucleo- 

 proteids, or, rather, of the nucleic acids and their cleavage-products, to the 

 decomposition products of the general metabolism. Indeed, many scien- 

 tists, largely from purely chemical considerations, were strongly in favor 

 of assigning to the nucleins a relation to the formation of uric acid. It 

 remained, however, for recent experiments to show that in man, and 

 mammals in general, the greater part and perhaps all of the uric- acid 

 results from the decomposition of the nucleic acids and their cleavage- 

 products, especially the purine bases. 



For a long time the attempt had been made to show that uric acid was 

 the antecedent of urea in the breaking down of proteins. In fact, the 

 amount of uric acid in the urine was even considered to be a direct expres- 

 sion of the activity of oxidations in the animal organism. The more 

 extensive these oxidation processes were, the less uric acid would be found 

 in the urine. Evidence against this assumption was brought forward from 

 time to time, and, above all, it was always claimed that in no case could 

 any direct relationship be shown between the uric acid excreted and the 

 disintegration of the albumins, and that there was no evidence that it 

 indicated the extent of the oxidation processes. Scientists always came 

 back to the above view, however, because it was not found possible to 

 show positively that there was an increased elimination of uric acid after 

 the administration of nucleic acids and purine bases. It was only by the 

 experiments of Horbaczewski 3 that the problem was cleared up. 



Horbaczewski showed with mammals that if the pulp or extract of 

 organs were digested for several hours out of contact with the air, purine 

 bases were formed, while exposure to the air gave rise to uric acid. On 

 adding nucleoproteids a better yield of uric acid was obtained. It was 



1 A. Schittenhelm and F. Schroter: Z. physiol. Chem. 39, 203 (1903). A. Schitten- 

 helm and C. Tollens: Z. innere Med. 25, No. 30 (1904). 



2 M. Kriiger and A. Schittenhelm: Z. physiol. Chem. 45, 14 (1905); 35, 153 (1902). 

 A. Schittenhelm: Dent. Arch. klin. Med. 81, 423 (1904). 



3 Horbaczewski: Monatsh. 10, 624 (1889); 12, 221 (1891). P.Giacosa: Att. R. Ace. 

 Scienze di Torino, 25, 726 (1891). W. Spitzer: Pfliiger's Arch. 76, 192 (1899). H. Wiener: 

 Verh. xvii, Kong, innere Med. 1889; 622 Arch, exper. Path. Pharm. 42, 375 (1899). 



