ix THE HISTONES 411 



gland. Tbe precipitate obtained in this way, on being shaken up 

 with 0'8 per cent hydrochloric acid, was supposed to break up into 

 histone (which remained in solution and which could be precipitated 

 by ammonia), and into leuco-nuclein, which was held to be an albumin 

 + nucleic acid compound. Since Lilienfeld's time the readily accessible 

 thymus-histone has been investigated by Kossel, Kossel and Kutscher, 1 

 Fleroff, 2 Bang, 3 Malengreau, 4 and Huiskamp. 5 



Lilienfeld's ' nucleo- histone ' consists, according to Huiskamp, 

 Malengreau, and Bang, of two distinct nucleo-albumins. Huiskamp 

 distinguishes between a nucleo-albumin free from histone and a nucleo- 

 histone; Malengreau between a nucleo-histone (A- nucleo -albumin) 

 and a histone -nucleinate (B-nucleo -albumin), and Bang between a 

 nucleo-albumin free from histone, a histone-nucleinate, and Fleroff's 

 para-histone. 



Before entering into these divergent views the author has given a 

 short account of the methods which have been employed by Malen- 

 greau, Huiskamp, and Bang for the separation of nucleo-albumins, 

 especially as these substances act as very strong oxydases, in which 

 connection they have been investigated by the author. 



Methods for separating ' Nucleo-albumins ' and ' Histone ' 



Malengreau' s Method. A watery extract of minced thymus is 

 repeatedly precipitated with acetic acid, and the precipitate redissolved 

 in sodium carbonate or caustic soda solution. From the final sodium 

 carbonate solution the ' nucleo-proteid ' or A-nucleo-albumin separates 

 out on being saturated to between 30 and 45 per cent with ammonium 

 sulphate, while the nucleo-histone or B-nucleo-albumin is thrown down 

 by 56 to 72 per cent saturated ammonium sulphate solution. By the 

 addition of 1 per cent HC1 to the 'nucleo-proteid' or A-nucleo-albumin, 

 Malengreau obtained a ' histone ' which was precipitated by 45 per 

 cent saturated ammonium sulphate, while the ' histone ' obtained by 

 1 per cent HC1 from the nucleo-histone or B-nucleo-albumin required 

 at least 55 per cent ammonium sulphate. Malengreau found both the 

 nucleo-histone and the nucleo-albumin to contain adenin and guanin. 



1 A. Kossel, Zeitschr. f, Chem. 30. 520 (1900) ; 31. 410 (1900) ; A. Kossel and 

 F. Kutscher, ibid. 31. 165 (1900). 



2 A. Fleroff, ibid. 28. 307 (1899). 



3 J. Emg^ibid. 27. 463 (1899); 30. 508 (1900); 31. 407 (1900); Hofmeisters 

 Beitrage, 4. 115 and 331 (1903) ; and 362 ; 5. 317 (1904). 



4 F. Malengreau, La Cellule, 17. 339 (1900) ; and ibid. 19. 285 (1902). 



5 W. Huiskamp, Zeitschr. f. physiol. Chem. 32. 145 (1901); 34. 32 (1901); 39. 

 55 (1903). 



