108 THE PROTEIN SUBSTANCES. 



which are not soluble in water, dilute salt solutions, or very dilute alkalies, 

 and only dissolve after being modified by strong alkalies. 



Histones are basic proteins which stand to a certain extent between 

 the strongly basic protamines (see below) and the true proteins. Their 

 content of nitrogen varies between 16.5 and 19.8 per cent, and in certain 

 instances is not higher than in other proteins, especially vegetable pro- 

 teins. According to KOSSEL and KUTSCHER and LAWROW they are, 

 on the contrary, richer in basic nitrogen, and especially yield more arginine 

 than other proteins. KOSSEL first isolated a peculiar protein substance 

 from the red corpuscles of goose blood which was precipitated by ammonia, 

 and because of its similarity in certain regards to the peptones (in the 

 old sense) he called it histone. At the present time a number of very 

 different bodies are described as histones, such as those obtained from 

 nucleohistone (LILIENFELD), from haemoglobin (globin according to 

 ;SCHULZ), from mackerel spermatozoa (scombron according to BANG), 

 from the codfish (gadushistone according to KOSSEL and KUTSCHER), 

 from the burbot (lotahistone, EHRSTROM), and from the sea-urchin 

 (arbacin, MATHEWS), although probably not all are true histones, 

 especially the above mentioned globin. 1 



Sulphur has been found in those histones in which it has been tested 

 for, but they do not, at least not all, give the lead-blackening test with 

 alkali and lead acetate. They give the biuret test, but as a rule only 

 a, faint MILLON'S reaction. The goose-blood histone first studied by 

 KOSSEL gives the three following reactions: First, the neutral salt- 

 free solution does not coagulate on boiling; second, gives a precipitate 

 with ammonia which is insoluble in an excess of the precipitant; third, 

 gives a precipitate with nitric acid which disappears on heating and 

 reappears on cooling. 



The different histones behave differently with these three reactions, 

 and hence they are not specific. On the other hand, all histones seem 

 to be precipitated from neutral solution by alkaloid reagents, and they 

 also produce precipitates in protein solutions. These two reactions are 

 likewise not specific for the histones, as the protamines have a similar 

 behavior. The histones differ from the protamines by having a much 

 lower content of basic nitrogen, and also probably by always containing 

 sulphur. True proteins, as OssoRNE's 2 edestan, also give these two 

 reactions; therefore it is impossible by qualitative tests alone to identify 



1 Kossel, Zeitschr. f. physiol. Chem., 8, and Sitzungbers. der Gesellsch. zur Beford. 

 -d. ges Naturwiss. zu Marburg, 1897; Kossel and Kutscher, ibid., 1900, and Zeitschr. 

 f. physiol. Chem., 31; Lawrow, ibid., 28, and Ber. d. d. chem. Gesellsch., 34; Lilienfeld, 

 Zeitschr. f. physiol. Chem., 18; Schulz, ibid., 24; Bang, ibid., 27; Ehrstrom, ibid., 

 32; Mathews, ibid, 23. 



2 Zeitschr. f. physiol. Chem., 33. 



