154 The Unity of the Organism 



derived by division from preceding units. These units have 

 so much in common both structurally and functionally that 

 the same name may be applied to them all. The name fixed 

 upon, though a bad misfit because of serious errors of obser- 

 vation and interpretation on the part of several early inves- 

 tigators, is cell. 



When held down to these narrower limits, the theory 

 contains no express reference to heredity ; it makes no claim 

 to "embracing all the hereditary qualities in its substance." 

 Still less does it contain even by implication the notion 

 that the "key to all ultimate biological problems must, in 

 last analysis, be sought in the cell." 



(c) Statement of Theory Justified by Present State of 



Knowledge 



I may now state categorically my view of the cell- 

 theory : If accepted in the broad signification given it by Wil- 

 son and many others, it must be recognized as consisting of 

 two very distinct parts. First, there is the part which ex- 

 presses in the generalization, no longer questioned by any 

 one, the cellular constitution of all organisms and the origin 

 of individual cells. And second, there is the vaguely hypo- 

 thetical part about the cells "embracing in their substance 

 all hereditary qualities," and for this and other reasons be- 

 ing the "ke}^ of all ultimate biological problems." If our dis- 

 cussion of "The organism and its cells" accomplishes its 

 aims, it will remove the vagueness of this second part of 

 the cell-theory, and in doing so, while questioning in no 

 manner any established truth which it contains, will reveal 

 the inadequacy of some of its central conceptions. 



"The whole of an organism is as essential to the inter- 

 pretation of its parts as the parts are to the interpretation 

 of the whole." So runs the first of our fundamental prop- 

 ositions. Let us substitute "cells" for "parts" in this and 

 examine it. The organism is as essential to the interpre- 



