i88 BOTANICAL GAZETTE [march 



were carefully mustered and four specimens of the semigigas type 

 were discovered. This makes a proportion of 4 to 8500, or about 

 0.05 per cent, showing the semigigas mutants to be only half as 

 frequent as the nanella. On later inspections no additional cases 

 were observed, and likewise intermediate or doubtful instances 

 were absent. The four plants were exactly alike, save that three 

 were very vigorous, and one, grown in a shady part of the garden, 

 was very weak. The chromosomes were counted in the first three 

 instances and found to be 21, as in the corresponding mutant of 

 Stomps. 



My four mutants were easily discovered by their broad conical 

 flower buds and their elongated spikes, which strongly contrasted 

 with the dense spikes of the surrounding biennis. They reached 

 the same height as these, the lowest flower being 90 cm. above the 

 soil, and the total height about i . 5 meters. The leaves had the 

 same form as those of biennis, but were a darker green and slightly 

 more pubescent. The pollen consisted of 3- and 4-cornered grains, 

 both of which types seemed fertile only for about a quarter. Arti- 

 ficial self-fertilization, however, had no result, and on the stigmas 

 of O. biennis, 0. gigas, and O. Lamarckiana the effect of the pollen 

 was very slight, inducing some swelling of the ovaries but no good 

 seeds or almost none. Inversely, I have tried to fertilize the 

 flowers with the pollen of the three species named, but got a good 

 result only in the case of 0. biennis. Numerous good capsules with 

 a sufficient supply of apparently good but in reahty empty seeds 

 have been obtained by leaving the flowers free to the agency of 

 insects in the midst of the thousands of their fl-owering sisters, 

 while in the same garden no other Oenotheras were grown. 



The three vigorous specimens of the mutant produced some 

 lateral rosettes at the base of their stem, even as we have seen in 

 the case of the parent species and the dwarf variety. These 

 rosettes were isolated and planted in pots in the beginning of 

 August; four of them were very vigorous, but the other one rather 

 weak. They have thrown off lateral rosettes themselves, and the 

 stems repeated the production in two instances. It is proposed 

 to try to bring these plants through the winter and repeat with them 

 the culture and the experiments of this year. After a month, their 



