THYMUS. 367 



protein substance which has been generally called nudeohistone. By the 

 action of dilute hydrochloric acid upon nudeohistone it splits, according 

 to these investigators, into histone and leuconudein. The leuconuclein 

 is a true nuclein; hence it is a nucleic-acid compound with protein which 

 is relatively poor in protein and rich in phosphorus. The more recent 

 investigations of BANG, MALENGREAU, HUISKAMP and GOUBAN l upon 

 nudeohistone all show that this nucleoprotein is not a unit substance, but 

 a mixture of at least two bodies. The views of the investigators men- 

 tioned differ quite essentially from one another as to the nature of these 

 bodies, but this is partly due to the different methods used by them and 

 partly to the ready changeability of the substances in question. 



Besides the real nudeohistone, B-nucleoalbumin of MALENGREAU, 

 LILIENFELD'S histone contains a second nucleoprotein which BANG and 

 HUISKAMP call simple nucleoprotein, while MALENGREAU designates 

 it A-nucleoalbumin. This protein, which contains only about 1 per cent 

 phosphorus and which is possibly identical with the nucleoprotein found 

 by LILIENFELD in the thymus, yields a nuclein, but no free nucleic acid, 

 on cleavage. As a second cleavage product it yields, according to MAL- 

 ENGREAU, the A-histone, which can be readily precipitated by magnesium 

 and ammonium sulphates from the ordinary B-histone of the thymus 

 gland. The occurrence of A-histone in the gland has been verified by 

 BANG, and according to BANG and HUISKAMP the A-histone is not derived 

 from the nucleoprotein, as these investigators claim that it yields no his- 

 tone. According to BANG the nucleoprotein yields only an albuminate, 

 besides the nuclein, as cleavage products. According to GOUBAN we 

 have been dealing with three substances, namely a nucleoprotein which 

 does not yield any histone, and two nucleohistones, which correspond 

 to the nucleoalbumins A and B of MALENGREAU and form the mixture 

 of lime-nucleohistone of HUISKAMP. They occur in this last mentioned 

 mixture in a somewhat modified form due to the method of preparation. 



The true nudeohistone, which is much richer in phosphorus (the 

 calcium salt containing, according to BANG, on an average 5.23 per cent 

 P), yields ordinary histone (or 2 histones) as one cleavage product and 

 free nucleic acid as the other. According to BANG, whose statements 

 on this point have been substantiated by MALENGREAU, it splits on saturat- 

 ing with NaCl into nucleic acid and histone without yielding any other 

 protein. On this account BANG does not consider this body as nudeo- 

 histone in the ordinary sense, i.e., not as a nucleoprotein, but as a histone 



1 Lilienfeld, Zeitschr. f. physiol. Chem., 18; Kossel, ibid., 30 and 31; Bang., ibid. 

 30 and 31. See also Arch. f. Math, og Naturvidenskab, 25, Kristiania, 1902, and 

 Hofmeister's Beitrage, 1 and 4; Malengreau, La Cellule, 17 and 19; Huiskamp, Zeit- 

 schr. f. physiol. Chem., 32, 34 and 39; Gouban, Bioch. Centralbl., 9, 803. 



