CHEMISTRY OF THE LEUCOMAINES. 309 



As to the origin of this sulstance in the organism very 

 little has been known up to within a few years, except so 

 far as it has teen shown to be, together with other members 

 of this group, a transitory product in the retrograde meta- 

 morphosis of nitrogenous foods and tissues. In the case of 

 the lower animals it is evidently the' end-product of all 

 change, inasmuch as it is excreted as such. Uur knowledge 

 as to the immediate origin of this and the other allied bases 

 has lately been extended by the brilliant researches of 

 KossEL on the decomposition products of nuclein, in which 

 he has shown that this essential constituent of all nucleated 

 cells, whether animal or vegetable, decomposes under the 

 action of water or dilute acids into adenine, guanine, hypo- 

 xanthiue, and xanthine. We know that the first two bases 

 are readily converted by the action of nitrous acid into the 

 other two ; that is to say, an NH group in these bases is 

 replaced by an atom of — a change which it is not at all 

 unlikely takes place in the tissues, perhaps in every cell 

 nucleus. That such a change is quite probable is shown by 

 the putrefaction experiments of Schihdlbe, whereby aden- 

 ine and guanine were converted respectively into hypoxan- 

 thine and xanthine. If this explanation is correct, then 

 adenine and guanine are transition-products between the 

 complex proteid molecule on the one hand, and hypoxan- 

 thine and xanthine on the other. These two, in turn, form 

 the connecting link to the last step in the regressive meta- 

 morphosis of the nitrogenous elements of the tissues, viz., 

 the formation of uric acid and urea. We can thus trace a 

 succession of cycles from' the complex nuclein molecule, 

 which is apparently indispensable to the functional activity 

 of all reproductable cells, to the physiologically waste pro- 

 ducts urea and uric acid. 



ScHULZE and Bosshaed recently (1886) found in young 

 vetch, clover, ergot, etc., a new base, to which they have 

 given the name vernine. It has the formula CieHjjNgOj, 

 and is o^ especial interest at this point, since on heating 

 with hydrochloric acid it apparently yields guanine. We 

 have, therefore, at least two well-defined sources of guanine, 

 the nucleins and vernine. 



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