158 The Unity of the Organism 



is specific organ-forming substance, the indubitable fact that 

 in normal development this substance is itself a product of 

 the organism's activities, throws it into a very subordinate 

 place as a cause of development. The truth is, the main 

 upshot of the effort to explain ontogeny on elementalistic 

 principles amounts to an effort to avoid recognizing the most 

 positive and definite entity in the whole situation, namely 

 the organism taken alive, normal and untampered with. 



A Peculiar Element alls t Objection to the Organic Whole 



We now come to the last point to be noticed in connec- 

 tion with the elementalist attempt to deal with internal se- 

 cretions as related to the organism as a whole. Instancing 

 the familiar way in which a particular part of a flat-worm 

 will give rise to a new head after being cut away from the 

 original animal, when no head would have been formed at this 

 place had not the animal been cut, Loeb writes : "How does 

 the 'whole' suppress all this formative power in the part be- 

 fore the latter is isolated? It almost seems as if the isola- 

 tion itself were the emancipation of the part from the tyr- 

 anny of the whole. The explanation of this tyranny or of 

 the correlation of the parts in the whole is to be found, how- 

 ever, in a different influence." 12 



Then follows the statement previously quoted about the 

 specific organ-forming substances of Sachs and other bot- 

 anists, and the assumed identity of these with internal se- 

 cretions. 



Without raising the question concerning the evidence for 

 the assumption that the production of a flat-worm's head 

 as indicated is dependent upon internal secretions, let us 

 consider a moment the interesting conception thrown into 

 the treatment that the whole flat-worm tyrannizes over its 

 parts. Why this? Is it "mere rhetoric"? We are not per- 

 mitted to judge it thus, for no one has pronounced against 



