VOLUME LX NUMBER 5 
THE 
BOTANICAL CAA7ET IE 
NOVEMBER 1915 
OENOTHERA GIGAS NANELLA, A MENDELIAN MUTANT 
Huco DEVRIES 
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 rapidly. 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 O. 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 O. 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 (0P. cit., 
p. 103), which behaves as a dominant in its crosses with O. 
Lamarckiana. 
In this article I hope to show that the dwarf character, which in 
so many instances complies 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, Huco, Die Mutations-Theorie. 1:223; 2:151-179, 420. 
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