6 BOTANICAL GAZETTE [JANUARY 
The‘antipodal polar appears regularly to issue from the pouch 
at an early stage, and asit passes into the body of the embryo 
sac it increases in size, until at the time it arrives in the vicinity 
of the other polar no difference in their dimensions is discernible 
(figs. 34, 41, 42). The polars soon approach one another and 
may remain for a long time in contact. Their actual fusion was 
not observed and seems not to occur until the time of fertiliza- 
tion, Shibata (14) has shown for Monotropa that pollination 
hastens the fusion of the polars. In Elodea neither pollination 
nor the entrance of pollen tubes into the ovary constitutes a 
sufficient stimulus. In ovules which have failed to receive pollen 
tubes the polars may still be seen lying side by side, even though 
surrounded in the same ovarian cavity by other ovules whose 
eggs have been fertilized, and which contain embryos. The 
actual presence of the pollen tube in the ovule seems to be 
necessary to bring about their union. Guignard (9) has shown 
a similar behavior of polars in Capsella. In this form the polar 
nuclei are distinct until the male elements penetrate into the 
embryo sac;,.their union appears to be Aiea ald however, 
before fertilization takes place. 
The antipodals always remain in the pouch in which they were 
formed, and before the entrance of the pollen tube are inconspic- 
uous and stain feebly. At the time of fertilization, however, 
and during the early development of the embryo, some activity 
is manifest in this region. The group then generally shows a 
fourth nucleus (jigs. 35, 36, 38, 39), the uppermost of which 
becomes quite large and may have more than one nucleolus. 
This enlarged nucleus is often surrounded by a considerable mass 
of cytoplasm which may be enclosed by a definite membrane, 
giving it the appearance of an egg (figs. 38, go). In rarer 
instances two enlarged nuclei are seen, making five in all (fig. 37), 
while not uncommonly the tip displays the usual number, three 
(fig. 40). 
The sudden appearance of the extra nucleus in the antipodal 
group, when one has in mind the behavior of the polars, might 
suggest that these nuclei do not always fuse, and that one of 
them passes down to!the lower end of the embryo sac and joins 
