336 CELL-CHEMISTRY AND CELL-PHYSIOLOGY 



cial nucleins, prepared by combining egg-albumin with nucleinic acid 

 in various proportions, show a varying affinity for basic and acid 

 dyes according as the nucleinic acid is more or less completely 

 saturated with albumin. Lilienfeld's starting-point was given by the 

 results of Kossel's researches on the relations of the nuclein group, 

 which are expressed as follows : ^ — 



Nucleo-proteid (i% of P or less), 

 by peptic digestion splits into 



Peptone Nuclein (3-4% P), 



by treatment with acid splits into 



Albumin Nucleinic acid (9-10% P), 



heated with mineral acids splits into 



Phosphoric acid Nuclein bases (A carbohydrate.) 



(adenin, guanin, etc.). 



Now, according to Kossel and Lilienfeld, the principal nucleo- 

 proteid in the nucleus of leucocytes is niiclco-Jiiston, containing about 

 3% of phosphorus, which may be split into a form of nuclein playing 

 the part of an acid, and an albuminoid base, the histon of Kossel ; 

 the nuclein may in turn be split into albumin and nucleinic acid. 

 These four substances — albumin, nucleo-histon, nuclein, nucleinic 

 acid — thus form a series in which the proportion of phosphorus, 

 which is a measure of the nucleinic acid, successively increases from 

 zero to 9-10%. If the members of this series be treated with the 

 same mixture of red acid fuchsin and basic methyl-green, the result 

 is as follows. Albumin (egg-albumin) is stained red, nucleo-histon 

 greenish blue, nuclein bluish green, nucleinic acid intense green. "We 

 see, therefore, that the principle that determines the staining of the 

 nuclear substances is always the nucleinic acid. All the nuclear sub- 

 stances, from those richest in albumin to those poorest in it, or con- 

 taining none, assume the tone of the nuclear {i.e. basic) stain, but the 

 combined albumin modifies the green more or less toward blue." ^ 

 Lilienfeld explains the fact that chromatin in the cell-nucleus seldom 

 appears pure green on the assumption, supported by many facts, 

 that the proportions of nucleinic acid and albumin vary with different 

 physiological conditions, and he suggests further that the intense 

 staining-power of the chromosomes during mitosis is probably due 

 to the fact that they contain a maximum of nucleinic acid. Very 

 interesting is a comparison of the foregoing staining-reactions with 

 those given by a mixture of a red basic dye (saffranin) and a green 

 acid one (" light green "). With this combination an effect is given 

 which reverses that of the Biondi-Ehrlich mixture ; i.e. the nuclein 



1 From Lilienfeld, after Kossel ('92, p. 129), ^ i^^., p. 394. 



