174 OENOTHERA LAMARCK1ANA MUT. VELUTINA. 



30 specimens of the bed richly flowered and ripened their first fruits 

 before being thrown away. 



0. Lamarckiana x 0. blandina. — A biennial plant of the species 

 was crossed in 1913 with a green individual of the mutant. The 

 seeds were sown partly in 1914 and in 1915. They gave the same 

 two types as in the reciprocal cross. During the whole lifetime there 

 were no visible differences. In the first year I had 60 plants with 

 22 per cent laeta, and in the second year 109 specimens with 25 

 per cent laeta; the remainder were velutina. Of these, 25 and 10 

 flowered, in about equal groups for both types, having been recogni- 

 zed and sorted out at the time of planting. The other plants were 

 cultivated till the end of June. 



0. blandina x 0. nanella. — Two green individuals were ferti- 

 lized in 1913 by the pollen of my race of 0. Lamarckiana mut. 

 nanella; the seeds of the one were sown in 1914 and of the other 

 in 1915. There were no dwarfs in this first generation, but only 

 laeta and velutina, which were just like those of the crosses already 

 described. I had 90 and 72 plants, with 74 and 67 per cent laeta. 

 There were 25 and 10 flowering plants belonging equally to the two 

 groups; the others were large rosettes in June. 



If we compare the percentages of laeta given with one another we 

 find for 0. blandina x 0. Lamarckiana 41 and 54 per cent, for the 

 reciprocal cross 22 and 25 per cent, and for the experiment with 

 the dwarfs 74 and 67 per cent; finally, for the second generation of 

 the first cross 33 per cent. The average of all these figures is 45 

 percent laeta, which comes as near to equality of the two groups 

 as may be expected. The diviations from this mean are probably 

 due mainly to the choice of the parents and to their cultural condi- 

 tions. 



0. rubrinervis x 0. blandina. — Besides the 3 crosses already 

 mentioned and discussed, I have also made the two reciprocal 

 crosses with my race of 0. rubrinervis. In the first generation they 

 split in the same way, the only difference being that instead of 

 the laeta another type arises. This is the subrobusta, which appears 

 in the hybrid splittings of 0. rubrinervis with other derivatives of 

 0. Lamarckiana, as described in my Gruppenweise Artbildung. No 

 differences were observed, although the comparison lasted from 

 germination till the ripening of the fruits. The other type was the 

 same as in the crosses already dealt with, and exactly like the 

 parental type of 0. blandina. 



The cross was made in 1913 between an individual of my pure 



