MUTATIONS, VARIATIONS, AND RELATIONSHIPS OF THE OENOTHERAS. 1 9 



(c) Eighty-eight specimens were grown from seed of an O. rubrinervis 

 which had appeared as a newly arisen mutant among the first generation 

 hybrid progeny of O. laniarckiana X biennis discussed in our earher account 

 (Mutants and Hybrids, p. 18). The occurrence of this mutant along with 

 several individuals of 0. lamarckiana was there attributed to an accidental 

 self-fertilization of the pistil parent, but there is no sufficient reason perhaps 

 for ruling out the occurrence of monolepsis producing Millardet hvbrids in 

 which the maternal characters alone appear. Whether this specimen of O. 

 rubrinervis was the product of self-fertilization or of monolepsis has no especial 

 significance for this study, since, whatever may have been its origin, it was a 

 true O. rubrinervis, though having no rubrinervis individuals in its ancestry, 

 at least for many generations. 



The pollination of this specimen was left entirely uncontrolled, and as it 

 grew in close contiguity with other species of Oenothera, where insects were 

 busily engaged carrying from flower to flower the pollen of a dozen or more 

 different species, the progeny might have been expected to show a confusion 

 of hybrid forms of unknown affinities. It was a matter of some surprise, 

 therefore, that only i specimen in the 88 appeared to be a hybrid. The char- 

 acters of this obvious hybrid indicated that it was probably produced by pollen 

 from one of the small-flowered species, and it was considered by the senior 

 author to be nearlv if not quite identical with his 0. lamarckiana X biennis, 

 No. 2.32, though no definite analysis of its characters was made. The other 

 87 individuals consisted of 80 0. rubrinervis and 7 which were looked upon as 

 typical O. lamarckiana, although, as will be seen later, the results of the statis- 

 tical studies present some interesting exceptional features. 



(rf) Twenty-seven individuals of O. rubrinervis were grown from guarded 

 and self-fertilized seed of one which arose as a mutant at Amsterdam in 1895 

 in a pure 0. lamarckiana pedigree guarded for six generations. 



(e) Ninety-eight specimens of Oenothera gigas were grown from pure-bred 

 seed received fromProf. DeVries, the pedigree being known and fully guarded 

 for five generations from the time it appeared as a mutant in 1895. Unfortu- 

 nately onlv 4 of these came to bloom the first year, so that the studies here 

 given on Oenothera gigas must be considered wholly inadequate. 



(/) Another lot of plants, 44 in number, were the offspring of Oenothera 

 lata which had grown surrounded by O. gigas in an isolated portion of the 

 Botanical Garden of Amsterdam. On the side of the pistil-parent the pedigree 

 of this lata had been continued for five generations from the time it arose as 

 a mutant, and in most of these generations 0. lamarckiana was the pollen par- 

 ent. As 0. lata is nearly or quite incapable of self-fertihzation, owing to its 

 lack of viable pollen, these plants must have been hybrids between 0. lata 

 and O. gigas, and as they were wholly unselected they formed a motley group. 

 Among them Oenothera lata was the most frequent, 17 in 44 belonging to this 



