MUTATIONS OF OENOTHERA SUAVEOLENS DESF. 251 



found among 120 seedlings 3 lutescens, or 2.5 percent. Thus the 

 mutability was seen to be the same in two succeeding generations. 



In 1915 I planted out 17 specimens of lutescens, rejecting the 

 weaker ones. I succeeded, however, in self-fertilizing only two of 

 them and got the next year 2 and 53 seedlings, all of which repeated 

 the characters of their parent. I also fecundated a third plant with 

 the pollen of the most vigorous individual, but got only 8 seedlings, 

 all of them lutescens. Although small, these figures show that this 

 mutant form is constant in its progeny. 



The question arose whether this constancy is due to the hereditary 

 qualities of both the male and female gametes, or only to one of them 

 as in the case of our sulfurea. For this reason I crossed the lutescens 

 with the species, in both directions. I found: 



Seedlings Pale green Dark green 

 Oe. lutescens x suaveolens 17 17 



Oe. suaveolens x lutescens 66 4 62 



The plants were cultivated until they flowered, but some of them 

 were lost from the reason already given, being too weak. If we assume 

 the four pale green individuals of the second cross to be due to 

 mutated egg cells of the female parent, the experiment shows that 

 the hereditary qualities of the offspring were, for this character, 

 decided by the mother and not by the father. In other words the 

 visible qualities of lutescens were handed down through the egg cells. 



(5) Oe. suaveolens mut. fastigiata (fig. 2) 



In early youth it is hardly possible to distinguish the two narrow- 

 leaved mutants from one another. In both of them the radical 

 leaves are almost linear with a long, sharp-pointed tip. Even at 

 the time of planting out, in the midst of April, I could not separate 

 the two forms, although some specimens had already somewhat 

 broader leaves. The individuals with the narrowest leaves are very, 

 weak from this cause and some of them do not survive the trans- 

 planting. For this reason 1 have preferred to determine the coef- 

 ficient of mutation jointly for both of them, and found in the ex- 

 periments described above for the production of Oe. mut. lutescens 

 5, 12, 2, 2, together 21, narrow-leaved mutants among the 1400 

 plants mentioned. This makes a percentage of 1.5. In the two con- 

 trol experiments I counted 5 and 6 of these mutants, among 630 

 seedlings, giving 1.6 percent. I planted out 30 specimens, lost three 



