96 NEW DIMORPHIC MUTANTS OF THE OENOTHERAS. 



previously described. It was fertilized, therefore, purely by its 

 own pollen. It yielded 0.8 cc. of seeds, which were sown in 1914 

 and gave rise to 65 plants, one of which was a mutant of the ordinary 

 type of 0. nanella, and subjected to the same bacterial disease 

 which so often deforms the dwarfs of my race. Among the others, 

 two types were represented in about equal numbers. One type 

 was exactly like normal Lamarckiana; it counted 36 individuals, 

 almost all of which have flowered, without showing any recognizable 

 difference from the original wild species. The remaining 28 con- 

 stituted a new and uniform type, repeating the characters of the 

 parent plant of 1913, so far as these had been noticed and recorded. 

 At the time of planting out, in the beginning of May, they very 

 much resembled the compact rosettes of 0. nanella, but without 

 any signs of the disease. About the middle of June, when the 

 rosettes of the type of Lamarckiana were growing very fast, those 

 of the new type remained small, their leaves reaching only about 

 half the length and half the breadth of those of their sisters 

 (7x3 cm. against 14 x 5 cm.). Their blades were sharply set off 

 from the winged petioles (fig. 5, C), and thereby they much resembled 

 those of 0. pallescens (fig. 4). This resemblance continued during 

 the development of the stem and the flower spikes; but even as the 

 rosettes were smaller and more densely leaved, the stems were 

 lower and weaker and less branched. The leaves were narrower 

 and folded along the middle vein, instead of being broad and flat- 

 tened, as in 0. pallescens. The flower buds were as thick and as 

 large as those of this species, and the flowers also reached the same 

 size, the petals having a length of 4 cm. During the flowering 

 period the differences from 0. pallescens grew gradually less, and 

 at the end, in September, the new type seemed to be only a weak 

 form of this latter, reaching a less height and being almost un- 

 branched. Artificial self-fertilization has been difficult, since in 

 many flowers the pollen was in an imperfect condition. Four 

 specimens yielded a sufficient harvest (0.5-1 cc). The sister plants 

 of the Lamarckiana type showed an abundance of seed, exactly 

 as the Lamarckiana of pure origin does. 



The next year (1915) I sowed the seeds of one specimen of the 

 parental type and of two of the type of Lamarckiana. The first 

 gave only 44 seedlings, of which 4 were Lactuca, one nanella, and 

 the others Lamarckiana. The two other sowings gave 248 and 283 

 offspring of their own type, without any Lactuca specimens, but 

 with some dwarfs. The number of them was 1 1, or 4 per cent in the 



