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THE AMERICAN NATURALIST [Vol. LIII 



a proof that the entire organism develops through the 

 combined activities of such particles. Moreover, even if 

 such a complete germinal representation of adult char- 

 acters were shown to exist, only a part— and a minor 

 part— of our difficulties would be solved. We should still 

 have to explain how the elementary parts of the body 

 came to arrange themselves in proper spatial order and 

 in proper chronological sequence during development. 

 Blocks do not build themselves into houses. Driesch 

 points out that historically vitalism and epigenesis have 

 always been closely related, while the mechanistic school 

 has commonly adopted some form of preformationism. 

 Such a connection is far from being logically necessary, 

 however. To me it would seem that preformation lent 

 itself most readily to vitalism— to the notion of a builder 

 who put the blocks together. In our particulate theories 

 of organic differentiation, we commonly leave out of ac- 

 count the spatial and chronological relationships of the 

 parts, or rather we take them for granted. We assume 

 that somehow our " organismules " will find their way to 

 their proper places at the proper moments, just as in a 

 laboratory experiment the experimenter himself sees to 

 it that everything is at each moment just where it be- 

 longs. 



Let us return to an illustrative case, already consid- 

 ered, and ask why no one has ever seriously proposed a 

 preformation theory of the earth's origin. Most mod- 

 ems (M. Bergson is an exception) believe that our pres- 

 ent world was the inevitable outcome of forces that were 

 inherent in a fairly homogeneous molten mass, interact- 

 ing with those of its cosmic environment. It has never 

 been thought necessary to invoke the aid of special ''de- 

 terminants" to account for the various geographic and 

 geologic features of our planet's structure. In dealing 

 with inorganic things we are content to let our analysis 

 rest, in the lack of more detailed information, with the 

 acceptance of such general principles as "creative syn- 

 thesis" or the "multiplication of effects." We simply 



