88 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 1.5 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, O. 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 O. biennis. Numerous good capsules with 
a sufficient supply of apparently good but in reality empty seeds 
have been obtained by leaving the flowers free to the agency of 
insects in the midst of the thousands of their flowering 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 
