MUTATIONS OF OENOTHERA SUAVEOLENS DESF. 255 



elaborately by Gagnepain (19(H)) from cultures derived from wild 

 seeds. I made the cross in 1914 between two individuals of my 

 cultures. From the seeds I raised 60 specimens, almost all of which 

 have flowered. They were a uniform lot and grew to a height of 

 about two meters. They strongly resembled the hybrids with other 

 species, in which Oe. biennis was the female parent and showed, 

 like these, the type known as conica, having weak stems with few 

 branches, a pale green foliage, large flower buds, etc. The leaves 

 were narrow with their margins folded upward, the flowers large 

 with petals of 3 cm. and with the stigma surrounded by the anthers, 

 insuring self-fertilization in the buds. They were clearly intermediate 

 between Oe. suaveolens and the conica type of the hybrids of biennis 

 and could easily be recognized as hybrids of these two types. 



In 1916 I cultivated a second generation of 70 flowering plants, 

 and compared them through all the time of their development. 

 There was no trace of splitting; all the specimens were alike, resem- 

 bling those of the previous year. 



Oe. suaveolens x biennis. — On account of the heterogamy of 

 Oe. biennis this cross cannot be expected to yield the same hybrids 

 as the reciprocal one. From crosses of other species, in which the 

 pollen of Oe. biennis was used, we must expect a prepotency of its 

 influence, and such has been the result of my exepriments. I made 

 the cross in 1914, but since 1 got too small a progeny from it, repeated 

 it in 1915. The first cross gave only 7 offspring, of which 6 were 

 very vigorous and strongly resembled the pollen parent, and one 

 a lutescens, which flowered like the Oe. suaveolens mut. lutescens 

 desciibed above. Of the 6 other hybrids one remained a rosette and 

 5 flowered in August and September. The cross of 1915 gave 59 

 offspring, three of which were lutescens and flowered. Among the 

 remaining individuals only 18 made a stem and 38 remained through- 

 out the summer in the condition of rosettes. 



It is evident that the specimens of lutescens in these cultures must 

 be considered as due to egg cells of Oe. suaveolens which had mutated 

 in this direction, and thus really constituted hybrids between Oe. 

 mut. lutescens and Oe. biennis. Since I had 4 of them among 66 

 specimens, their percentage was 6 percent, a relatively high figure, 

 but about the same as in the cross between Oe. suaveolens and Oe. 

 mut. lutescens (4 lutescens among 62), as described above. The seeds 

 of these lutescens yielded in 1916 a uniform progeny of 37 annual 

 plants, among which 14 flowered in August. 



From the seeds of the main type of the hybrids of 1915 I had in 



