VOLUME LX NUMHER 5 



THE 



Botanical Gazette 



NOVEMBER 1915 



OENOTHERA GIGAS NANELLA, A MEND ELIAN MUTANT 



Hugo DeVhies 



In a recent book Gates has studied the significance of the experi- 

 ments made with species of Oenothera as proofs for the general 

 theory of mutation, and has given an exhaustive and critical review 

 of the facts in this raJDidly increasing field of research.' He has 

 laid special stress upon the results of crosses, which show the great 

 diversity of these phenomena when studied in some wild plants, as 

 contrasted with the now prevailing doctrine of Mendelism; for 

 among the mutants of Oenothera instances of Mendelism are rare. 

 The first known example is that afforded by 0. brevistylis, which 

 follows the law of Mendel as a recessive in all its crosses with the 

 parent species, with other mutants, and with other species of the 

 same group." But, unfortunately, the production of this form by 

 means of mutation from 0. Lamarckiana is so rare that it has not, 

 as yet, been repeated under experimental control. Another 

 instance is O. rubricalyx, discovered and studied by Gates {op. cit., 

 p. 103), which behaves as a dominant in its crosses with 0. 

 Lamarckiana. 



In this article I hope to show that the dwarf character, which in 

 so many instances comphes with the formulae of Mendel, but 

 which behaves in a different way in crosses of the derivatives of 

 O. Lamarckiana, may, at least in one instance in this group, follow 

 that law as exactly as in any other pure Mendelian case. This 



' Gates, R. R., The mutation factor in evolution. London. 1915. 

 ' DeVries, Hugo, Die Mutations-Theorie. 1:223; 2:151-179,429. 



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