300 BACTERIAL POISONS. 



hypoxanthine, etc., that from undeveloped eggs and from 

 milk yields no nitrogenous bases on treatment with acids. 

 But as the egg develops, i.e., the nucleated cells increase in 

 nuiaber, this latter nuclein is gradually converted or gives 

 way to the ordinary cell nuclein, and hence it is that the 

 chick embryo yields guanine, hypoxanthine, and possibly 

 adenine. 



Unquestionably, the presence of hypoxanthine, etc., in 

 developing cells is due to the presence of the nuclein mole- 

 cule, from which it is readily split off. In muscle, however, 

 hypoxanthine and xanthine appear to exist preformed, and 

 bear no relation to nuclein, since they are in the free condi- 

 tion, and can be extracted from the tissue by water. For 

 an explanation of this peculiar fact, see Adenine, page 284, 

 and Guanine, page 308. 



According to the observations of Salomon and Chit- 

 tenden, hypoxanthine is formed by the digestion of blood 

 fibrin with gastric juice, pancreatic juice, or on heating with 

 water or dilute acids. Egg albumin under the same con- 

 ditions does not yield any hypoxanthine, except when 

 treated with pancreatic juice. These observations require 

 repetition, inasmuch as the fibrin used undoubtedly con- 

 tained nuclein, which, as we now know, readily decomposes 

 under those conditions into its characteristic nitrogenous 

 bases. Be that as it may, it appears, however, to be one 

 of the products formed by the decomposition and succes- 

 sive oxidation of proteid matter previous to the formation 

 of uric acid and urea. 



When a mixtui'e of guanine, xanthine, and hypoxanthine 

 is allowed to putrefy, the bases decompose and disappear in 

 the order named. Hypoxanthine resists bacterial action 

 the longest, and this corresponds with its behavior to re- 

 agents (Baginsky). Adenine during putrefaction, in the 

 absence of air, is converted into hypoxanthine, and guanine 

 is correspondingly changed into xanthine (Schindler). 

 An imido group is, therefore, replaced by oxygen, and 

 probably goes to form urea. This conversion is a very 

 important fact, since the process of putrefaction, as Hoi'PE- 

 Seylee has repeatedly pointed out, is analogous to the 



