148 ANDERSON: EMBRYOGENY OF MARTYNIA LOUISIANA 
third the length of the embryo-sac. The egg-apparatus consists 
of the large pear-shaped egg-cell, which extends far down into 
the sac cavity, and the two large synergids (PLATE 8, FIG. 26, 
GandSn). The lower part of the egg in which the nucleus lies is 
well filled with cytoplasm, but the upper part is vacuolate. The 
synergids, one on either side of the egg, extend down about two 
thirds the length of the egg-cell. Each synergid has a diameter 
nearly equaling that of the egg and a centrally located nucleus, 
which is a little smaller than the egg nucleus. As is frequently 
found in other angiosperms, a fairly large vacuole lies below the 
nucleus in the synergid (Fic. 26, Sn). 
In the chalazal end of the embryo-sac are the three, rather 
long, slender, well-developed antipodals (Fic. 26, N). In most 
instances, the nuclei of the antipodals are fairly large and the 
cytoplasm has the character of that of the body of the embryo- 
After the formation of the cells at either end of the embryo-sac 
the polar nuclei move to the center and lie side by side for some 
time (Fic. 26, Pn), but before the pollen tube reaches the embryo- 
sac, the two polar nuclei fuse (FIG. 27). Sections were made of 
ovaries from flowers in which pollination had not occurred and 
it was found that the polar nuclei had fused (Fic. 28). So the 
fusion of the polar nuclei is in no way due to a stimulus from 
the pollen tube. The fusion nucleus does not approach the egg- 
apparataus, as Kanda reported for Verbena (2), but remains in 
the center of the embryo-sac. Each polar nucleus has a very 
prominent nucleolus and after fusion the two nucleoli are very 
noticeable for some time (FIG. 27), but later only one large 
nucleolus is usually seen (Fic. 28). 
POLLINATION 
The polar nuclei seem to unite about the time of anthesis, 
for conditions like those represented in F1G. 26 are observed in 
ovaries fixed just before the expansion of the corolla lobes, while 
the fusion nucleus is seen in flowers that have been open one or 
two hours. Most of the flowers open early in the morning, and 
shortly after daylight the bees, which are the chief pollinizing 
agents, are busy gathering nectar from the lower portion of the 
corolla tube. 
