378 CHEMISTRY OF THE LEUCOMAINS. 



The pancreas according to Hammarsten yields a nucleo-proteid 

 which on decomposition gives chiefly guanin. Bang has prepared 

 a nucleinic acid, presumably from this proteid, which on hydrolysis 

 yields guanin (34.35 per cent.) and no other base. Glycerin, phos- 

 phoric acid and pentose are the other products. Should Bang's work 

 be confirmed it will go to show that there are several nucleinic acids 

 in the pancreas, inasmuch as adenin and traces of xanthin and hypo- 

 xanthin have been obtained from this organ (Kossel, Levene). 



As to the origin of this substance in the organism very little has 

 been known up to within a few years, except so far as it has been 

 shown to be, together with other members of this group, a transitory 

 product in the metabolism of nitrogenous foods and tissues. In the case 

 of the lower animals it is evidently the end-product of all change, inas- 

 much as it is excreted as such. Our knowledge as to the immediate 

 origin of this and the other allied bases has been extended by the bril- 

 liant researches of Kossel and his pupils on the decomposition prod- 

 ucts of nuclein, in which he has shown that this essential constituent 

 of all nucleated cells, whether animal or vegetable, decomposes un- 

 der the action of water, dilute acids or enzymes into adenin, guanin, 

 hypoxanthin, and xanthin. We know that the first two bases are 

 readily converted by the action of nitrous acid into the other two ; 

 that is to say, a NHj group in these bases is replaced by an atom of 

 O — a change which it is not at all unlikely takes place in the tis- 

 sues, perhaps in every cell nucleus. That such a change is quite 

 probable is shown by the putrefaction experiments of Schindler, 

 whereby adenin and guanin were converted respectively into hypo- 

 xanthin and xanthin. If this explanation is correct, then adenin 

 and guanin are primary transitional products between the complex 

 nucleo-proteid on the one hand, and hypoxanthin and xanthin on 

 the other. These two, in turn, may form the connecting link 

 between the former and the final waste products uric acid and urea. 



Schulze and Bosshard (1886) found in young vetch, clover, ergot, 

 etc., a new base, to which they have given the name vernin. It has 

 the formula C^^^f>^ , and is of especial interest at this point, 

 since on heating with hydrochloric acid it apparently yields guanin. 

 We have, therefore, at least two well defined sources of guanin, the 

 nucleins and vernin. 



Neither adenin nor guanin occurs in normal muscle further than 

 in mere traces, a fact which can only be explained on the ground 

 that the muscle tissue is poor in nucleated cells, and hence in 

 nuclein. Just as the muscle cell has become morphologically differ- 

 entiated from the typical cell, it may be looked upon also as having 

 undergone a concomitant chemical differentiation (page 349). 



Guanin and creatin apparently mutually replace one another. 

 Thus, in the muscle, as just stated, guanin occurs only in traces 

 whereas creatin is especially abundant. This may find its explana- 



