386 



Profs. A. Gamgee and W. Jones. 



[Feb. 9, 



Preliminary Remarks concerning the " Nucleoproteids" and " Nucleins" 

 and the Sense in which the Latter Term is used in the Present\Papet. 



By the term Nucleoproteids, we designate complex, or rather 

 compound, albuminous substances which are the constituents of the 

 nucleated protoplasm of all the organs of the animal body, but 

 especially of the ductless, as well as of the secreting, glands. These 

 bodies are characterised by the large quantity of phosphorus which they 

 contain, by the constant presence of iron, and by the fact that under 

 the influence of heat, by the action of acids, of alkalies, but especially 

 of pepsin and hydrochloric acid, acting at temperatures favourable to 

 their action, they split up into albuminous matters, and into so-called 

 true (to distinguish them from pseudo-) nucleins. The latter differ 

 from the mother nucleoproteids which yielded them, by the fact 

 that they result from the splitting-off of a fraction of the albuminous 

 •molecules which these contained in their pristine and native con- 

 dition. These secondary, or we may say, degraded nucleoproteids. 

 "the nucleins," contain all the phosphorus originally present in the 

 mother substance. 



By the action of caustic alkalies and heat, the nucleins yield as 

 products of decomposition, albuminous matters, and the so-called 

 " nucleinic acids," bodies which vary in composition in the different 

 nucleoproteids, but which are characterised by the fact that when 

 heated with certain mineral acids, they yield as products of hydro- 

 lysis (Kossel), one or more of the purin-derivatives long known as 

 " the xanthine bases," Adenin (Amidopurin), Guanin (Aminooxypurin), 

 Hypoxanthin (Oxypurin), and Xanthin (Dioxypurin), as well as in 

 many cases a base called Thymin, C.^H.iXoOo, a derivative of Pyrimi- 

 dine.* At the same time, the phosphorus is separated as phosphoric 

 acid. 



Kossel, to whose fine researches we owe the greater part of our 

 knowledge of the nucleinic acids, advanced the hypothesis (based on 

 the great variation in the quantities of the xanthine bases which 

 result from the hydrolysis of nucleinic acids of different origins) that 

 there are four nucleinic acids, each of which yields one of the bases 

 only. This theory of Kossel appeared to gain important support 

 from Ivar Bang's t discovery of guanylic acid, a nucleinic acid obtained 

 by the action of solution of potassium hydrate on the nucleoproteids 

 of the pancreas, and which, as its name indicates, yields on hydrolysis 

 one only of the purin-bases, viz., guanine. This hypothesis does not 



* "Walter Jones, ' Zeitschrif t f. phjsiol. Cliem,.' vol. 29 (1900), p. 26; H. 

 Steudel u. A. Kossel, 'Zeit. f. physiol. Chem., 3 vol. 29 (1900), p. 303; H. Steudel, 

 ' Zeitschr. f. physiol. Chem.,' vol.' 30 (1900), p. 539; vol. 39 (1901), p. 241. 



f Ivar Bang, " Die Guanylsanre der Pancreasdriise und deren Spaltungspro- 

 dukte," 'Zeitschr. f. physiol. Chem.,' vol. 30 (1898), p. 133. 



