LAMARCKIANA SEMIGIGAS. 



687 



In my previous race of Oe. spatliulata x blandina 1 counted 25 

 percent of barren grains, and among the viable germs I observed 

 30 percent laeta, 52 percent blandina, 18 percent spatliulata and very 

 few mutants (de Vries 1924 b, p. 213). The constitution of the mutants 

 from semigigas may therefore be considered as sensibly the same 

 as that of the race. The mutants in the cultures of 1924 were 1 lata, 

 3 auricula, 2 hamata, 1 liquida, and in the second and third experi- 

 ment 10 plants of a uniform but new type, with small, rounded 

 and shiny leaves. 



Oenothera semigigas Mut. hamata. 



Under this name I have described a very rare mutant, which, 

 however, originated from different strains (de Vries 1924 b, p. 216). 

 The same type is, curiously enough, not at all rare among the mu- 

 tants from Oe. semigigas. From the cross with velutina I had two 

 flowering specimens of a pure type and with 15 chromosomes (de 

 Vries 1924 b, p. 261), which gave, after self-fertilization, a progeny 

 whose constitution is shown in table 5. 



Table 5. 

 Oenothera semigigas mut. hamata. Second generation. 



My race of this name had given, as an average from two generations, 

 82 percent Lamarckiana and 31 percent hamata, besides about one-half 

 of barren seeds. The constitution of the new mutants was, therefore, 

 sufficiently the same as that of the race. Both were splitting mutants 

 of the ordinary dimorphic type. The mutants were, in 1924, one 

 liquida and one of the form of diluta. 



Oenothera semigigas Mut. pulla. 



This type, which has not been remarked until very recently, is 

 now easily recognized in the phase of the rosettes as well as during 



