358 



OENOTHERA RUBRINERVIS, A HALF MUTANT. 



Although the cultures were but small, they show that the devia- 

 tions from the theoretically expected result (25 per cent) do not 

 depend upon the method of counting as used in 1916. 



In this race I self-fertilized the first mutant deserens observed 

 in 1914 and derived from it a second and a third generation in 1915 

 and 1916. The second generation consisted of 95 plants, of which 

 50 flowered; the third was derived from two parents and embraced 

 77 and 140 specimens, among which 60 and 60 were left to flower. 

 All of these cultures were wholly uniform at the time of planting 

 out as well as during the flowering period. No rubrinervis and no 

 new mutants occurred among them. Thus 0. deserens is seen to 

 constitute a pure and uniform race. 



The percentage of empty grains among the seeds has been given 

 elsewhere for this race of 0. rubrinervis 1 ). The determination was 

 made in the harvest of 5 plants of the third generation grown in 

 1910 and 1915, and in that of two specimens of the fourth genera- 

 tion of 1915. I found 53—68 per cent of germs, with a mean of 60 

 per cent. Among the specimens of deserens, quoted in the same 

 table, 5 belonged to this race; their seeds contained 96, 99, 94, 83, 

 and 85 per cent of good germs. Thus we see that the empty grains, 

 which are a character of 0. rubrinervis, have disappeared almost 

 wholly in the new mutant. 



My second strain of 0. rubrinervis was derived from ano.ther mutant 

 of 1895. It has not been used for any crosses except those mentioned 

 in this article, and which served as control for the experiments in 

 the main line. Part of the seeds of 1895 were sowed in 1907 and yielded 

 a second generation from which a third has been derived in 1913 

 and a fourth in 1914. I counted the deserens for three parent plants 

 as previously described and found the percentages as follows: 



Percentage of 0. deserens in cultures of 0. rubrinervis 



The results agiee exactly with those deduced from the previous 

 table. The suspicion, however, that in the two last cases the per- 

 centage figures were found too low, on account of losses of speci- 

 mens of deserens at the time of planting out, induced me to repeat 



l ) Zeitschr. f. Ind. Abst. 16: 262. 1916. Opera VII, p. 131. 



