138 O'NEAL: EMBRYO SAC DEVELOPMENT IN OENOTHERA 
ovule at the time of fertilization is shown in Text FIG. 2. Placen- 
tation is central. _ 
Early development of the ovule-——The anlage of the ovule is 
first noticed as a slight bulge or swelling on the wall of the 
loculus as shown in PLATE 
5, FIG. 1. Fic. 2 shows a 
stage slightly more ad- 
vanced, in which the hump 
is a little more pronounced. 
There is no evidence of cell 
nz differentiation at this time. | 
1G. 3, of a still later stage, 
shows a section of an ovule 
~ shortly before the appear- 
ance of the inner integu- 
ment initials. Fic. 4 shows 
the initial development of 
the inner integument. In 
the same section the large 
hypodermal cell which func- 
tions as an archesporium 
may be observed. e Oc- 
currence of this cell in the 
development of ovules seems 
Pr to have been noted first ky 
Fic. 2. Acamera lucida diagram of the Strasburger (26) in a plant 
ovule of Oenothera rubrinervis showing the z ayy 
deeply imbedded embryo sac, C; the nu- Which he did not name. It 
cellus, A; the inner integument, B; the was found later by Mottier 
oiien integument, D; and the micropyle, (22), who gave the former 
E. credit for first reporting it. 
Kny (18), in his series of charts that has been used extensively 
in college courses of botany, does not show this cell for Oe. 
biennis, but since the time of this publication, the cell has 
been observed repeatedly in other genera and Geerts (15) de- 
scribed it for Oe. Lamarckiana. Fic. 5 is of a section in which 
two hypodermal cells may be seen lying side by side. Such a 
condition will result in the formation of two embryo sacs lying 
side by side, as found by Ishikawa (17) in Oe. pycnocarpa and 
Oc. nutans. 
iS 
