The Organism and Its Cells 1G3 



is tlic primary factor; for the characteristic mode of growth 

 is often shown by tlie growing mass before it splits up into 

 cells, and the form of cell-division ada])ts itself to that of 

 the mass: 'Die Pflanze bildet Zellen, nicht die Zelle bihlet 

 Pflanzen.' Much of tlic recent work in normal and experi- 

 mental embryology, as well as that on regeneration, indi- 

 cates that the same is true, in principle, of animal growth. 

 . . . Still more recently this view has been almost demon- 

 strated through some remarkable experiments on regenera- 

 tion, which show that definitely formed material, in some 

 cases even the adult tissues, may be directly moulded into 

 new structures." ^*^ 



I go no farther here in the examination of Wilson's biolog- 

 ical philosophy than to point out that, in spite of his clear 

 perception, as indicated by these quotations, that the organ- 

 ism as a wliole plays a determining part in the development 

 of its constituent elements, his latest statements show that he 

 is succeeding all too well in obeying the ancient injunction : 

 "Let not thy right hand know what thy left hand doeth." 

 Presumably his left hand still clings to the "whole mass 

 as a moulding power of the parts." But his right hand 

 seems now more confident than ever of finding the "key to 

 all ultimate biological problems" in the cells, or maybe in 

 the chromosomes. 



In a lecture published in 1913, speaking of the inter- 

 esting phenomenon of "criss-cross heredity" in the short 

 and jong-winged flies lately studied by Morgan, where the 

 sons are like their mothers and the daughters are like their 

 fathers, Wilson says: "This case, and many others of similar 

 type, may be completely explained througli our knowledge 

 of the relation of the chromosomes to sex. . . . All the facts 

 revealed by experiment are very simply and completely ac- 

 counted for by the simple assumption that the x-chromosome 

 is responsible not only for sex, but also for the short-winged 

 charactex\" ^^ Our critical examination of this whole mat- 



