378 BOTANICAL GAZETTE [May 
in O. Lamarckiana (6, 9), but was shown by Davis (3) to occur in 
O. grandiflora also. I found that the twin hybrids may be considered 
as a consequence of the mass mutation, the mutated gametes produ- 
cing one of the twins and the typical sexual cells the other. This 
conception evidently may be applied to O. Lamarckiana and make 
some previous hypotheses superfluous,' but this point must be 
reserved for another article, 
I shall first describe my cultures and crosses of O. grandiflora in 
a purely empirical way and afterward discuss their results in con- 
nection with those of BARTLETT. 
A. MUTATIONS OF O. GRANDIFLORA 
One of the last days of September 1912 I visited with BARTLETT 
a station of O. grandiflora in the neighborhood of Castleberry, 
Alabama. It was on the border of a cornfield situated along the 
railroad. The station seemed to us to be pure, since no other 
species of the same group could be discovered either in the field 
itself or in its neighborhood. The number of specimens was small, 
but had been very large some years ago, when the field was not 
cultivated. A few specimens bore ripe capsules, which we col- 
lected. From their seeds I started ro pure strains. One of them 
was continued through four succeeding generations (1913-1916), 
whereas the others were abandoned as soon as they proved to con- 
tain in the main the same derivatives. 
This race produced in my garden three mutations, two of which 
were observed in every generation, but the third was very rare, 
occurring only once.?_ All of them were constant in their progeny. 
I shall call them ochracea, characterized by broad and pale leaves, 
mostly weak and of a low stature (fig. 1); Jorea, with almost linear 
leaves and somewhat narrower petals (fig. 2); and gigas, with stout 
stems, broad leaves and flower buds, large flowers, and 28 chromo- 
* See Gruppenweise Artbildung. The conception of RENNER that the twins, and 
with them all mutability, might be the effect of a hypothetical hybrid condition of 
O. Lamarckiana, runs in some respects parallel to this view, but is contradicted by 
it on its main points: See Zeitschr. Ind. Abst. und Vererbungs. 16: 279-284. 1916. 
* All of the seeds for the different cultures were soaked in water under a pressure 
of 8 atmospheres during about 48 hours, and then sown at 30° C. in the greenhouse, 
so as to induce the most complete germination. 
