CHAP. III.] XANTHINE-BASES. 261 



Are Xanthine-bases products of digestion by Trypsin? 



, t r Xanthine C.H 4 N 4 2 . 

 Hypoxanthine C 5 H 4 N 4 O. Guanine C 5 H 5 N 5 0. 



We have now, before concluding our account of the well-defined 

 products which arise by the action of trypsin on the proteids (inde- 

 pendentJy of putrefactive bacteria) to consider briefly and to examine 

 the value of the facts which have been placed on record, and which 

 might, at first sight, appear to establish some relation between 

 the bases enumerated above (and often designated xanthine-bases 1 ) 

 and pancreatic digestion. 



Scherer's ^ n n * s i nvest igations on the bases which are con- 



discovery of tained in various tissues and organs, Scherer found small 

 guanine and quantities of guanine and xanthine in the tissue of 

 xanthine in the pancreas of oxen 2 . The amounts do not, however, 

 differ materially from those found in other glandular 

 organs and fail, therefore, to establish any special 

 connection between these bodies and pancreatic proteolysis. Chitten- 

 den, in the course of a research to be afterwards referred to, found 

 that the pancreatic tissue contains an appreciable quantity of 

 hypoxanthine and xanthine, but he proved that these bodies pre- 

 existed in the pancreas and were not the products of auto-digestion, 

 as their amounts did not increase when the dried pancreatic tissue 

 was digested at 40 C. for 24 48 hours in a weak alkaline solution. 



The observa- Hypoxanthine and xanthine in small quantities 



tions of Salo- were stated by Salomon 3 and by Krause 4 , who worked 

 mon and of under him, to be products of the digestion of blood- 

 fibrin by pepsin as well as by trypsin. These authors 

 further stated that both bodies were likewise formed when fibrin is 

 digested at the temperature of the body with weak hydrochloric 

 acid. 



Working under Klihne's direction, Chittenden 5 

 Chittenden's re p eate d Salomon's experiments. He found that when 

 researches. , , r , ,,, . , . r , . ,. ,. .,, .,, 



blood-fibrin is subjected to digestion either with pepsin 



or trypsin, small but easily recognisable quantities of the silver 

 compound of hypoxanthine could be obtained. He likewise obtained 



1 Hypoxanthine and xanthine have been dealt with at length in Vol. i. (1st edition, 

 pp. 329 332). A full description of Adenine will be found in the 2nd edition of Vol. i., 

 in connexion with the chemistry of the Nucleins. Guanine will be described in 

 Vol. m. In this place we shall only refer to these bodies so far as they appear to 

 bear on pancreatic digestion. 



2 Scherer, Annal. d. Chem. u. Pharm., Vol. cix. p. 257. 



3 Salomon, ' Ueber die Verbreitung und Entstehung von Hypoxanthin und Milch- 

 saure im thierischen Organismus,' Zeitschr. f. phys. Chemie, Vol. n. (1878 79), 

 pp. 6595 ; refer to p. 90. 



4 Hugo Krause, Ueber Darstellung von Xanthinkorpern aus Eiweiss, ' Inaug. Diss. 

 Berlin, 1878. 



6 K. H. Chittenden, ' On the Formation of Hypoxanthin from Albumin,' Journal 

 of Physiology, Vol. n. (187980), pp. 2837. 



