262 HYPOXANTHINE DERIVED FROM NUCLEINS. [BOOK II. 



hyppxan thine when he subjected blood-fibrin to the action of 

 boiling water, as well as when he digested it for two or three days 

 with a 2 p.c. sol. of hydrochloric acid at the temperature of 40 C. 



Chittenden, in comparative experiments, shewed that when egg- 

 albumin was substituted for fibrin, no hypoxanthine could, with 

 certainty, be discovered, except in the case of the pancreatic digestion 

 of egg-albumin, in which he obtained positive results. 



As will be shewn in the sequel, the cardinal fact to be made out 

 was whether blood-fibrin contains hypoxanthine preformed or not. 

 In the former case, Salomon's and Chittenden's results would merely 

 prove that under the circumstances of their experiments hypoxan- 

 thine had been dissolved out of the fibrin in which it had been 

 occluded. Chittenden believed that he had proved that fibrin 

 does not contain hypoxanthine, by boiling it for long periods with 

 absolute alcohol, and then examining the alcohol, which was 

 found to be free from hypoxanthine. Drechsel 1 , however, shewed 

 that this experiment does not by any means settle the question of 

 the absence of hypoxanthine from fibrin. 



Kossel's re- I n the vear 187" 9 Dr Albrecht Kossel published a 



searches on nu- research 2 on the nuclein of yeast, in which he an- 

 cieins and their nounced that amongst the soluble products of its de- 

 relations to composition was a not inconsiderable quantity of 

 hypoxanthine. , , i T n > i i i 



hypoxanthine. In a subsequent paper 3 he shewed 



that when the nuclein of yeast is merely boiled with water, a 

 quantity of hypoxanthine (which he estimated at about 1 per cent.) 

 is formed, this body being split off from the nuclein molecule. 



Extending his researches to nucleins from other sources he 

 similarly proved that, under the same circumstances, they yield 

 hypoxanthine. From these facts, Kossel argued that the small 

 quantities of hypoxanthine found by Salomon and Chittenden when 

 blood-fibrin was digested with pepsin and trypsin, were derived from 

 the nuclein of the white blood corpuscles necessarily occluded in the 

 fibrin, and that these experiments, therefore, in no way sufficed to 

 prove that hypoxanthine or xanthine are products of the decomposi- 

 tion of proteids either by pepsin or trypsin 4 . 



Kossel has shewn that not only hypoxanthine but likewise 

 xanthine and guanine result from the decomposition of nucleins. 



1 Drechsel, ' Zur Frage nach der Entstehung von Hypoxanthin aus Eiweisskorpern, ' 

 Ber. d. deutsch. chem. Gesellschaft, Vol. xm. p. 240. 



2 Dr Albrecht Kossel, 'Ueber das Nuclein der Hefe,' Zeitschrift f. phys. Chem-, 

 Vol. in. (1879), p. 284291. 



3 Dr Albrecht Kossel, ' Ueber die Herkunft des Hypoxan thins in dem Organismus,' 

 Zeitschrift f. phys. Chem., Vol. v. (1881), pp. 152157. 



4 Salomon has adopted the view of Kossel as to the origin of hypoxanthine from 

 nuclein : " Nachdem ich gezeigt hatte dass das Nuclein als die Quelle dieser Korper im 

 Organismus anzusehen ist, sind alle Experimente, die man fur die Bildung dieser 

 Substanzen aus den Eiweisskorpern angefuhrt hat, hinfallig geworden. Salomon hat 

 meine Beweise anerkannt und damit seine friihere Ansicht zuriickgezogen." Kossel, 

 ' Zur Chemie des Zellkerns,' Zeitschrift fiir physiolog. Chemie, Vol. vn. pp. 7 22 

 (see pp. 15 and 16). 



