ix THE NUCLEO-HISTONES 415 



96 per cent alcohol and centrifugalises at once. The precipitate is 

 now mixed with distilled water, allowed to stand for some hours, 

 and the water filtered off; the residue, thoroughly rubbed up with 

 50 to 150 ccm. of 2 per cent NaCl, filters readily after 24 hours. 

 The filtrate containing the histone-sodium nucleinate is a perfectly 

 clear somewhat bluish, fluorescent solution. To precipitate the 

 histone-sodium nucleinate, the 2 per cent salt solution is mixed with 

 an equal bulk of water, as the nucleinate is not soluble in 1 per cent 

 NaCl ; by still further dilution the precipitate passes, however, into 

 solution again and may then be precipitated by 0'2 per cent CaCl 2 . 



On saturating a solution of histone-nucleinate with solid powdered 

 NaCl the histone moiety is thrown down, while the nucleic acid 

 remains in solution. The latter may now be precipitated with 

 alcohol. To purify the nucleic acid either lead or copper salts may 

 be used, with which it forms insoluble precipitates, or silver or 

 mercury salts with which water-soluble but alcohol-insoluble salts are 

 formed. Dilute acetic acid does not, while 25 per cent acid does, 

 precipitate nucleic acid, but acetic acid quickly decomposes nucleic 

 acid into purin-bases and phosphoric acid. For analysis Bang used 

 the sodium nucleinate. 



When a histone-nucleinate solution is saturated with sodium 

 ihloride to obtain the histone, and when in the filtrate the nucleic 

 icid is precipitated with alcohol, there still remains a substance in 

 >olution which is Fleroff' s 1 para-histone. It gives the biuret reaction. 



The histone -calcium -nucleinate has the following percentage 

 omposition : 



C H ' N S P Ca Ash 



43-69 5-60 16-87 0'47 5'23 1*71 8'57. 



The nucleinate of histone is thus characterised by a very high 

 phosphorus content. By calculating the empirical formula from Ca, 

 we obtain 



C 85 H 130 N 28 S 0'34 P 4 Ca ^ 38 , 



trebling this formula because of the sulphur the minimal molecular 

 weight of 6974 is got from 



C 255 H 390 N 84 SP 12 Ca 3 1U . 



The para-histone, according to Fleroff, has the percentage com- 

 position : 



C 51-84 H 7-93 N 17-84 S 1-99. 

 Bang found : N 17'72 S 2'23. 



1 F. A. Fleroff, Zeitschr. /. physiol. Chem. 28. 307 (1899). 



