196 Edmund B. Wilson 



tin."^^ If attentively considered the facts summarized above will, 

 I think, clearly show the inadequacy of such an explanation. 

 Why should a given quantity and quahty of chromatin always 

 reappear in the same morphological form as that in which it 

 entered the nucleus ? Why, for example, in Metapodius should 

 the minute fraction of chromatin represented by a single small 

 supernumerary always reappear in the form of such a chromosome, 

 showing specific peculiarities of behavior, rather than as a corre- 

 sponding enlargement of one of the other chromosomes ? Why 

 should a larger excess always appear as a group of two, three, or 

 more supernumeraries that differ definitely in behavior from 

 the others and show constant size relations among themselves ? 

 Specifically, in individual No. 40, why should two small supernu- 

 meraries and two large ones always appear, rather than three large 

 ones ? In species where a constant quantitative chromatin-differ- 

 ence exists between the sexes, why should the excess in the female 

 always appear in the same form as that which appears in the female- 

 producing spermatozoa — in one case as a large idiochromosome 

 instead of a small (Lygaeus), in another as an additional chromo- 

 some of a particular size (very large in Protenor, small in Alydus, 

 of intermediate size in Anasa), in a third case as three additional 

 chromosomes (Galgulus) .^ 



To these and many similar questions which the facts compel 

 us to consider, I am unable to find any answer on the merely 

 quantitative hypothesis. Each of them receives a simple and 

 intelligible reply under the view that it is the number, size, and 

 quahty of the chromosomes that enter the nucleus that determine 

 the number, size, and mode of behavior of those that issue from 



'^ Pick's treatment of these cases is worth citing. "Es muss von vornherein als wahrscheinhch be- 

 zeichnet werden, dass unter den abnormenUmstanden,da einmal die Zahl der'Chromatin-Manoverein- 

 heiten' (im Sinne meiner Manoverhypothese gesprochen) in der Zelle erhoht ist, diese Zahl sich erhalt" 

 (p. 96). Why should the number be maintained ? Because, we are told, "Die Erhaltung der erhohten 

 Zahl und ihre regelmassige Wiederkehr bei den folgenden Teilungungen muss bei dem nun einmal 

 uber die Norm erhohten Chromosomenbestand der Zelle als der einjachere, leichler verstdndliche Vor- 

 gang erscheinen, als es ein besonderer, ein "Regulation" auf die Norm her\'orbringender Akt ware." 

 To most readers this will seem like an argument for, rather than against, the hypothesis of genetic 

 continuity. But since it is obviously not thus intended I can discover no other meaning in the passage 

 than that with a given "bestimmte Chromatinmanoverart" characteristic of the species (p. 1 15) the num- 

 ber of chromosomes formed is proportional to the quantity of chromatin-substance. 



