2 10 
Notes on Recent Literature . 
which attains more or less complete expression in hybrids with 
biennis as the mother: the same applies to muricata. 
Many other crosses between the species and their hybrids have 
been carried out, and confirm the explanation advanced : and similar 
phenomena have been found to occur in crosses between biennis 
and several other species of (Enothera. The phenomena of 
“ heterogamy ” are explained by a theory of segregation of characters 
combined with selective sterility of half the ovules and pollen grain. 
Sterility of 50% of the ovules and pollen grains has been shewn to 
occur widely in (Enothera spp., 1 but there is as yet no experimental 
proof of the theory of selective sterilisation, however probable such 
may appear. 
The suggestion that Oenothera Lamarckiana is of hybrid origin 
has frequently been made to account for part of its remarkable 
mutability. M. Leclerc du Sablon 2 has constructed a theoretical 
scheme in terms of known facts of Mendelian inheritance, gametic 
coupling, etc., by which the appearance of occasional “ mutations” 
would be produced among the offspring of a hybrid plant. On the 
practical side, Dr. Bradley M. Davis 3 has published results which 
shew that plants bearing a striking external resemblance to 
Lamarckiana can be produced by crossing biennis with 
grandijtora : his second paper contains detailed descriptions, 
drawings, and photographs. Davis found, however, that the hybrids 
shewed a great amount of segregation in F 2 , and in this important 
respect they differ from the Lamarckiana grown by de Vries and 
others, which shews only occasional deviations from type. Further, 
the theory of the hybrid origin of Lamarckiana from biennis 
and grandijtora fails to give any probable interpretation of the 
appearance of such striking mutants as nanella the dwarf, 
gigas with its double number of chromosomes, and possibly also 
the pollen-sterile lata : though it may be conceded that at least 
the two first are sports of types not comparable with such forms as 
scintillans and rubrinervis. Gigas can be paralleled elsewhere, and 
does not imply hybridisation : it is on the production of such forms 
as rubrinervis that evolution chiefly depends, according to the 
mutation theory; and it is precisely these forms which are open to 
suspicion as being products of segregation among characters 
blended by hybridisation. 
In this connection the historical evidence is important. It 
appears that the Lamarckiana used by de Vries is related to 
plants grown by Messrs. Carter & Co., of London, about I860. 4 
1 J. M. Geerts. “ Beitrage zur Kenntniss der Cytologie und der 
partiellen Sterilitat von- CE. Lamarckiana. Recueil Trav. Bot. 
Neerlandais: V., p. 93, 1909. 
2 “ De la nature hybride de l’CEnothfere du Lamarck.” Rev. gen. 
Bot. XXII., p. 266, 1910. 
3 ” Genetical Studies on CEnothera. I.—Notes on the Behaviour 
of Certain Hybrids of CEnothera in the First Generation.” 
Amer. Naturalist XLIV., p. 108, Feb. 1910. II.—“ Some 
Hybrids of CE. biennis and CE. gvandiflora that resemble CE . 
Lamarckiana." Ibid , XLV., p. 193, Apr. 1911. 
4 De Vries. “ Uber die Dauer der Mutationsperiode bei CE. 
Lamarckiana." Ber. d. d. bot. Ges. XXVIa., p. 382, 1905. 
