O’ NEAL: EMBRYO SAC DEVELOPMENT IN OENOETHRA 135 
rubrinervis at the rate of about one to five. Gates (13) states 
that Oe. rubricalyx has arisen from Oe. rubrinervis by a mutation 
that is fundamentally chemical in its nature. He states that 
the difference between the two forms is chiefly one of amount 
of anthocyanin produced. Shull (25) attacked this position 
and showed by experimental evidence that it was erroneous. 
The plants with which the latter worked, however, were o 
uncertain ancestry and Gates insisted that they were hybrids. 
Lutz (20), who has made a cytological study of the species, 
makes a chromosomal distinction between the Amsterdam 
plant and the representatives found in Indiana. Davis (8) and 
others have stoutly maintained the hybrid origin of Oe. Lamarcki- 
ana itself. Davis (4) has been able to produce a plant resembling 
the small-flowered form of Oe. Lamarckiana by crossing Oe. 
fransciscana and the Dutch Oe. biennis. In his most recent 
paper on the subject (8), this writer states that Oe. Lamarckiana 
arose as a hybrid somewhere in Europe about the middle of the 
last century. In an earlier publication (7) he stated that “with 
but little doubt, it has come down to us, possibly greatly modified, 
from certain plants placed upon the market by the seedsmen 
Carter and Company, of London, about 1860.” Gates (13) is 
inclined to accept the hybrid origin of Oe. Lamarckiana but is 
of the opinion that there is no evidence for thinking that its 
germinal instability has arisen from a single cross. De Vries 
originally assumed that Oe. Lamarckiana was a native American 
species. Leveillé (19),* in a publication which the writer has 
been unable to secure, states that Oe. rubrinervis reverts to Oe. 
biennis. As described by De Vries, the plants when young 
have leaves with red veins, stems with poorly developed bast 
fibers, and flowers with “stripes of red of varying width upon 
the sepals.’’ Lutz (20) asserts that the Amsterdam plants have 
a tendency to produce flowers with crinkled edges, while the 
Indiana plants usually produce flowers with smooth edges. 
The plants from which the material for this study was taken 
were grown from seed from an Oe. rubrinervis mutant that ap- 
peared in a sowing of Oe. Lamarckiana seed sent to Professor 
D. M. Mottier by DeVries in 1913. Pollination has been guarded, 
* Monographie du genre Oenothera. Le Mans. 1908. Review by S. B, 
Parish in Plant World 13: 66-72, 
