290 LECTURE XIII. 



also shown by feeding experiments that the administration of nucleo- 

 proteids and of purine bases increased the elimination of uric acid. Sim- 

 ilarly the formation of uric acid is increased when a food rich in purine 

 bases e.g., meat, liver, thymus, etc. is added to a definite diet. 1 



Horbaczewski himself believed that the uric acid was derived in the 

 first place from the nucleic acids, or their purine bases, obtained from 

 leucocytes, and his work was followed by a large number of investigations 

 concerning this question. It was, in fact, found that there was a certain 

 relation between the amount of uric acid eliminated and the number of 

 leucocytes. A particularly pregnant example, according to this view, is 

 given in leucaemia, a disease which in its entire aetiology is but little under- 

 stood. One of its most prominent symptoms is a more or less extensive 

 increase in the number of leucocytes. The observation that the increased 

 elimination of uric acid, so often noted during this disease, is dependent 

 on the destruction of leucocytes, is undoubtedly true. The generalization 

 that the uric acid of urine could only result from the destruction of the 

 above-mentioned cells was not, however, correct. 2 All the other cells of 

 the organism must be considered in the same manner. The most impor- 

 tant result of the investigations of Horbaczewski is that the purine bases, 

 in minced organs and tissue extracts, can, in the presence of oxygen, be 

 converted into uric acid. 



To prevent any misunderstanding, we will state at this point, that the 

 increased elimination of uric acid can, in no case, be looked upon as evidence 

 of an increased cell destruction. It may just as easily arise from an 

 increased cellular metabolism; i.e., from the breaking down and recon- 

 struction of the cell-body, and especially of the nuclei. 



Before discussing the mechanism of the conversion of purine bases 

 into uric acid, we wish to devote a little space to an important investiga- 

 tion of Burian and Schur. 3 These two scientists showed that by a diet 

 containing no purine bases it is possible to diminish appreciably the excre- 

 tion of uric acid, but not to prevent it entirely. It is noteworthy that the 

 amounts of uric acid then excreted remain practically constant for each 

 individual, but vary with different individuals. 4 Burian and Schur desig- 



1 R. Burian: Med. Klin. 1, 131 (1905). E. Salkowski: Virchow's Arch. 117, 570 

 (1889). C. v. Noorden: Lehrbuch d. Path. d. Stoffwechsels, 54, Berlin, Hirshwald, 

 1893 (new ed. 1906). C. Dapper: Berliner Klin. Wochsch. 30, 619 (1893). W. Cam- 

 merer: Z. Biol. 28, 72 (1891); Z. physiol. Chem. 33, 139 (1896). A. Schittenhelm : 

 Z. Stoffw. u. Verdauungskrankheiten, 5, 226 (1904). H. Wiener: Ergebnisse Physiol. 

 I, 1, 555 (1902). 



2 Mares : Monatsh. 13, 101 (1892). 



3 R. Burian and H. Schur: Pfliiger's Arch. 80, 241 (1900) ; 87, 239 (1901). Cf . E. W. 

 Rockwood: Am. J. Physiol. 12, 38 (1905). 



4 Schreiber and Waldvogel: Arch, exper. Path. Pharm. 32, 69 (1899). Cf. M. Kauf- 

 mann and L. Mohr: Arch. klin. Med. 74, 141 (1902). 



