No. 524] CHROMOSOMES AND HEREDITY 453 



By a curious twist of logic Boux brought the chromo- 

 somes into the discussion, lie argued that the karyo- 

 kinetic figure is an instrument of such a sort that we 

 must suppose its function to ho that of nicely separating 

 at each division the different kinds of materials of which 

 the chromosomes are composed, or supposed to be com- 

 posed. Were it only necessary, he argued, to divide the 

 chromatin quantitatively into equal parts a far simpler 

 mechanism ought to suffice. Weismann took this argu- 

 ment in good faith, and 1 mi It up his theory upon it. 



But if one thing seems more certain than anything 

 else in modern cytological work it is that in most cases 

 the karyokinetic figure divides the chromatin of the chro- 

 mosomes into exactly e^ual parts, irrespective of what 

 the fate of the cells is to be. We find that the chromo- 

 somes in the different tissues are identical as far as our 

 methods reach. Observation gives a positive denial to 

 the Roux-Wiosmann assumption. In fact. Boux himself 

 has later abandoned this position. We find in many 

 quarters a strong disinclination to the view that the chro- 

 mosomes are responsible hi tins sense for. the process of 

 development. 



This feeling has interested me a good deal in recent 

 years, especially since I myself have felt the same disin- 

 clination to reduce the problem of development to the 

 action of specific particles in the chromosomes. In my 

 own case and possibly in the minds of others this hesita- 

 tion is due in the first place to a distaste for the particu- 

 lar form of this theory that Weismann has made so pro- 

 nounced a feature of his speculations, and in the second 

 place to a feeling that it is unsafe or unwise to reduce 

 the problem of heredity ami development to a single 

 element in the cell; when we have every evidence that in 

 embryonic development the responsive action of the cyto- 



