276 The Unity of the Organism 



tractile vacuole and excretory pore. The origin of the mem- 

 branellae in this way particularly appealed to Johnson. "The 

 gradual evolution," he says, "of structures so complicated as 

 membranellae, from a mass of indifferent protoplasm, is very 

 striking." *'' What he has especially in view is that these "or- 

 ganula," as he calls them, arise not from the ectoplasm, to which 

 in the adult they seem to pertain, but from the endoplasm. 



Although Johnson was not much of a speculator, he was 

 still on the lookout for questions of general interest. "Our 

 ignorance," he remarks, '*of the primum movens to a neofor- 

 mation is complete. We can only say it lies in some peculiar 

 molecular condition that incites the duplication of existing 

 organs. And the working out of the impulse thus given 

 is only partly dependent upon temperature, food, the size of 

 the individual, or even as Balbiani's and my own experiments 

 in merotomy show, upon the intact condition of the organ- 

 ism." "^^ The reader should not fail to see that this is an 

 obvious, though somewhat indirect, recognition of the organ- 

 ism as a cause of developmental phenomena — of appealing 

 to the organism as a causal explanation of observed occur- 

 rences. In saying that the primum movens to organ pro- 

 tluction lies in "some peculiar molecular condition," the just 

 clainis of the potency of elements (of some sort) is recog- 

 nized. But no one should fail to notice the qualifying term 

 peculiar appended to molecular. The molecular condition 

 capable of producing the observed results is no general con- 

 dition ; it is a particular condition. And particular how.'^ 

 To the organism possessing the organs to be duplicated. 

 When the discussion of a purely objective case like this 

 proceeds normally, the reference is entirely to the organism 

 and its organs and tissues, and the conception cell does not 

 enter into it in any way. For example, there is no occasion 

 whatever even to refer to the nucleus. If the idea of the 

 cell is brought in at all, it is lugged in purely arbitrarily. 



One of the things that h^ts given enibryology its great 



