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THE AMERICAN NATURALIST 



[Vol. XLV 



of new forms under conditions that are not typical of 

 those of nature in the wild. For these reasons such evi- 

 dence could never appeal with so much force as would 

 direct experimental proof that a wild species is in the 

 habit of producing suddenly new types sufficiently dis- 

 tinct from the parent form to rank as new species or even 

 as strongly marked varieties. 



In ''Die Mutationstheorie" of De Vries the behavior 

 of (Enothera Lamarckiana in giving- rise to the so-called 

 mutants is presented as evidence that new species have 

 come into existence without intermediate steps from a 

 form which is assumed to he typical of a species in na- 

 ture. (Enothera Lamarckiana is made to bear the 

 weight of an elaborate hypothesis, treating of funda- 

 mental problems, very much as the apex might be made 

 to bear the weight of an inverted pyramid. As the equi- 

 librium of the inverted pyramid depends upon the sta- 

 bility of its apex, so the value for the mutation theory 

 of the evidence from the behavior of Lama rckiana must 

 rest with the status of this plant as a form truly repre- 

 sentative of a typical species. 



De Vries from the beginning took it for granted that 

 (Enothera Lamarckiana was a native American species 

 introduced into Europe, an assumption that was perhaps 

 not unnatural, although dangerous when the responsibil- 

 ity of direct proof of the origin of species by mutation 

 was laid upon its behavior. As far as the writer is 

 aware, 0. Lamarckiana, as a wild American species, is 

 unknown. No American locality can be cited where it 

 may be found as a clear component of the native flora. 

 There are certain records of its presence under condi- 

 tions that indicate the possibility of its being sometimes 

 a garden escape, and there is some herbarium material, 

 referred to Lamarckiana, which, however, has not been 

 tested by culture and was collected at times when the im- 

 portance of the most critical judgment in identification 

 was not appreciated. It cannot be said that American 

 botanists are not alive to the importance of the status of 



