Igo BOTANICAL GAZETTE [MARCH 
same group, although it grew among them and did not show any 
higher degree of vigor. 
The fact that sulfurea mutants were observed in the progeny 
of every one of the 7 parents of my culture directly proves this 
line of mutability to be hereditary in the whole family derived from 
the 1905 rosette from Wyk aan Zee. In combination with the 
sporadic occurrence of the pale-colored variety in our sand dunes, 
we may further infer that this mutability is hereditary in the whole 
stock of our country, and probably also in the whole species, since 
sulfurea plants have been found from the time of TOURNEFORT 
in France and other European countries. 
From the mutants constant races may be derived. I sowed 
the self-pollinated seeds of the four mutants of Stomps, and culti- 
vated 205, 225, 271, and 358 seedlings, altogether 1059 plants, all 
of which have flowered and produced only pale-yellow petals, 
making a very striking impression of constancy. When crossed 
with the pure species, the sulfurea strains give uniform hybrids 
which are patroclinous. Those of O. biennisX sulfurea have the pale 
flowers, those of O. biennis sulfurea X biennis show the same bright 
yellow as the parent species.%? 
On experimental germination of seeds 
Of the seeds of Oenothera Lamarckiana ordinarily only about 
one-third produce seedlings, and this proportion is highly variable, 
depending mainly on the conditions of cultivation of the parent 
plant. Among the remaining seeds some contain a normal embryo, 
others a more or less completely decayed one, while still others 
are empty. The last have been thoroughly studied by RENNER, 
who found that they have been fertilized as well as the normal 
seeds and those with decayed embryos. Between these normal and 
externally normal seeds are seen the numerous rudimentary ovules 
which have not been fertilized, and have not essentially increased 
their size after the fertilization of the others. These rudimentary 
seeds have been described by GEERTs, as referred to above. 
38 Self-pollinated seeds of this second generation of es biennis sulfurea are ‘available 
for exchange in return for other races of mutating primr 
3 Gruppenweise Artbildung. p. 298. 
