Studies on the Variability and Heritability of Pigmentation in Oenothera. 371 
O. Lamarckiana >= O. rubricalyx, and its reciprocal, both give O. Lamare- 
kiana and O. rubricalyx in the F,; O. rubricalyx =< O. nanella gives 
O. rubricalyx and O. Lamarckiana in the F,; and O. biennis = O. rubri- 
calyx gives the twin hybrids, laeta and velutina. 
The fact that crosses between O. Lamarckiana and O. rubricalyx give 
alternative inheritance, demonstrates the non-universality of Mendelian 
behavior. DE VRIES has shown that several of the mutants, when 
crossed with O. Lamarckiana, give alternative inheritance, and I have 
confirmed some of these results in unpublished experiments. It may 
be found to be the case that, in crosses between biotypes, the pheno- 
mena of alternative inheritance!) are as common as those of Mendelian 
dominance with splitting in each generation. No satisfactory hypothesis 
has yet been framed to account for the now well-established cases of 
alternative as distinguished from Mendelian inheritance. 
7. The reverts from O. rubricalyx to O. rubrinervis, so far as tested, 
behave in every way like O. rubrinervis of pure pedigree. 
8. The difference between O. rubrinervis and O. rubricalyx remains 
constant when the plants are grown in such diverse localities as 
Wood’s Hole, Mass., Chicago, Ill., and St. Louis, Mo. 
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1) I mean by alternative inheritance, both parental types appearing in the Fy 
and both breeding true in later generations. 
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