100 



NEW DIMORPHIC MUTANTS OF THE OENOTHERAS. 



the fruits thin and long. The production of pollen was insufficient 

 in many flowers, but this may have been the effect of the indi- 

 viduals being transplanted from their boxes to the bed in June, 

 which is relatively late in the season. The seed developed badly 

 and contained only a small percentage of normal grains. 



I have sown the seeds of 8 of the 9 specimens with the parental 

 type, and of two of the type of 0. biennis Chicago. The first split 

 into two types, the second only repeated the form of the parent. 

 The splitting percentages were 11, 12, 13, 15, 15, 17, 18 and 25, 

 with a mean of 16 per cent, but the germination had been very 

 poor, giving only 444 seedlings for the 8 boxes. The progeny of 

 the two specimens of the Chicago type was uniform with 252 and 

 60 seedlings. I counted them in May and June, and left one group 

 of each type to flower. The group from the saligna type contained 

 two flowering saligna, identical with those of the second generation ; 

 that of the atavists 60 flowering plants of the uniform type of 

 0. biennis Chicago. From these facts we may conclude that in 

 this race all of the specimens of the parental type give a dimorphic 

 progeny, while the offspring of the plants with an atavistic type 

 remains uniformly so. Resuming the cultures, we get the following 

 pedigree: 



1913 Mutant 



1914 Second generation 



1915 Third generation 



Mutant 



50 per cent saligna 



16 per cent saligna 



Chicago 



Chicago 



Chicago 



The behavior is exactly the same as in the dimorphic races 

 issued from 0. Lamarckiana. 



Crosses of Oenothera Lamarckiana mut. cana.— As indicated 

 on p. 682 I chose in 1913 the second generation of a cana mutant 

 which arose from 0. lata (no. 3) for a series of crosses. This cul- 

 ture was the most vigorous one of all my annual cana families, and 

 its percentage figures seemed to be more normal than in the other 

 cases. The crosses were made in both directions with the pure 

 strains of my species and races described in Gruppenweise Art- 

 bildung, and the seeds were sown in 1914. This first generation 

 was counted in July, during the beginning of the flowering period, 

 but about one-half of some of the cultures were kept in the boxes 

 so as to reach only the stage of rosettes at that time. No second 

 generations have been cultivated. I will first describe the results, 



