328 APPENDIX 4 



such a name as chromatin will perhaps become useless, unless 

 even then it still commends itself on account of its brevity.' ^'^^ 



In this book the word is used precisely in Flemming's sense. 

 Despite all that has been done since his time to enlarge our know- 

 ledge of nucleoproteins and DNA, we still do not know exactly to 

 what substance or substances in nuclei and chromosomes the 

 special affinity for particular dyes, to which Flemming refers, is 

 due. It may perhaps be nucleoprotein, but DNA split off from 

 protein by the action of a fixative seems more likely ; possibly, in 

 some cases, the protein may itself hold basic dyes after detachment 

 of DNA. It seems safest for the present to retain Flemming's 

 word when describing what we see in microscopical preparations 

 coloured with the usual dves. 



