158 The Unity of the Organism 



the other, tlic parent organism or the germ-cells? If the 

 cell-theory be taken in the broad sense above considered, 

 the aspect of it which we are holding to be erroneously 

 hypothetical, would answer that the germ-cells interpret the 

 parents. According to our standpoint, on the other hand, 

 this hypothesis is inadequate in that it tells at least no more 

 than half the truth. The parents interpret the germ-cells 

 quite as truly as the germ-cells interpret the parents. They 

 follow each other in a casually related, regularly alternating 

 series; and biology has no inductive ground for supposing 

 that either term came first in any ultimate sense. 



Certai/n Inadequacies of the Cell-Theory 



Having now seen that, in the general development and 

 formulation of the cell-theory, it is literally true that the 

 organism has interpreted the cell as much as the cell has 

 interpreted the organism, we must see something of how 

 this works out in detail. 



The impossibility of fully explaining an organism in terms 

 of its constituent cells seems to have been felt earlier and 

 more poignantly by students of the normal development 

 of individuals than by any other class of biologists. De 

 Bary's epigrammatic statement, already quoted, "The plant 

 forms cells; the cell does not form plants (Die Pflanze bildet 

 Zellen, nicht die Zelle hildet- Pflanzen)^^ was induced primar- 

 ily by observations of his own and others on developing 

 plants. Here it is easily demonstrable that the form of 

 the growing tip is often assumed before the mass divides 

 up into cells. In other words, the- formation of cells is 

 certainly in these cases a secondary even though an essential 

 phenomenon.^ ^ 



(a) As Tested by Embryonic Development 



On the side of animal development, C\ O. Whitman was 

 the first to produce arguments, both comprclicnsive and ir- 



