The OrcjanUm and Its Cells 105 



zation will probably play some part in it. But in what man- 

 ner that will happen we are quite unable to predict." "^^ 



I conclude this inventory of expressed recognitions by 

 competent observers that the organism dominates its cells 

 in embryogenesis, with two modes of formulating this recog- 

 nition that are specially significant. They are expressions 

 of the unity or oneness of the individual organism in time; 

 and of its unity or oneness in space. 



E. G. Conklin has expressed the first truth with com- 

 mendable decisiveness and simplicity: "Furthermore, from 

 its earliest to its latest stage an individual is one and the 

 same organism ; the egg of a frog is a frog in an early stage 

 of development and the characteristics of the adult frog 

 develop out of the Qgg^ but are not transmitted through it 

 by some 'bearers of heredity.' " -^ This proposition is so 

 nearly self-evident that it would not need insisting upon 

 but for its having been obscured by sophistical discussions 

 of whether development is "predetermined" or "epigenetic." 

 Huxley stated it in essence when he declared it to be "certain 

 that the germ is not merely a body in which life is dormant 

 or potential, but that it is itself simply a detached portion 

 of the substance of a pre-existing living body." 



Nageli put it in still more concrete terms when he af- 

 firmed that the hen's Qgg differs from the frog's Qgg as 

 much as the grown-up hen differs from the grown-up frog; 

 that the species is no less certainly contained in the vgg 

 than in the adult. However this speculator befogged the 

 truth with his fanciful idioplasm. The best expression of 

 the spacial unity of the developing organism with whicli T 

 am acquainted is that by F. R. Lillie : "The traditional 

 view, held by many embryologists at the present day, is that 

 the physiological unity arises in the course of embryonic 

 development by the secondary adaptation of originally in- 

 dependent parts to one another. But this ex})lanation has, 

 in my opinion, become untenable, and nmst be replaced by 



