I9I5] 



BARTLETT— MUTATION IN OENOTHERA 



99 



whether or not mut. nummularia is really as nearly self-sterile as 

 this conaparison would indicate. At any rate, only 403 seeds, 

 many of them obviously too unripe to germinate, were obtained 

 from 3 plants of the mutation. The seeds have given an Fi progeny 

 of 13s plants which is now (April 1914) in the early seedling stage. 

 The Fi generation from mut. nummularia consists in part of 

 plants which exactly reproduce the parental type and in part of 

 secondary mutations. At the time this article is being written 

 the plants are stUl young, but it is nevertheless clear (i) that the 



Fig. 8. — Flowers and buds of (a) Oenothera pratincola mut. nummularia, and 

 (6) typical 0. pratincola, showing especially the difference in the rupture of the calyx. 



Fi generation includes no typical 0. pratincola; (2) that the second- 

 ary mutations (with one possible exception) are narrower leaved 

 than 0. pratincola and therefore even more sharply distinguished 

 from mut. nummularia than the latter is from 0. pratincola; and 

 (3) that all of the secondary mutations (again with the single excep- 

 tion noted above) appear to be quite identical with certain primary 

 mutations which have appeared simultaneously with mut. num^ 

 mularia in various cultures of typical 0. pratincola. 



The secondary mutations fall into three well marked groups 

 which have been called mut. tortuosa, mut. rubricentra, and mut. 



