Brown: EMBRYO-SAC AND EMBRYO IN PHASEOLUS 539 
of the family studied by him; Hegelmaier (1880), also, did not see 
the antipodal cells and seems to have confused endosperm cells 
with the egg apparatus; according to Guignard (1881) the antipo- 
dal cells of Phaseolus multiflorus are ephemeral; and Strasburger 
(1880) found that the same is true of the antipodal cells of four 
species of Lupinus. 
The egg grows after its formation (PLATE 25, FIG. 10) and 
becomes long and broad at the base so that it projects into the 
embryo-sac beyond the synergids (PLATE 26, FIG. 15). The egg 
nucleus becomes larger and a large vacuole appears in the cyto- 
plasm toward the micropylar end of the egg. The synergids 
develop a distinct filiform apparatus (FIG. 15) whose striations 
arise from the neighborhood of a vacuole at the broader end of 
each synergid. Martin (1914) described a filiform apparatus in 
Trifolium pratense, but with more conspicuous striations than 
those which I have observed in Phaseolus vulgaris. The syner- 
gids change from a pear-shaped to a more narrow tapering form. 
After fertilization the synergids disintegrate and entirely disappear. 
The polar nuclei come to lie close together just below the egg 
(Fic. 14) and remain in this position for some time. Before fer- 
tilization, however, they come into close contact with each other 
and begin to fuse (Fic. 16), but it is quite possible that their fusion 
: may not be completed before the male nuclei enter the sac and one 
of the latter fuses with the polar nuclei. 
In one preparation a pollen tube was seen entering the embryo- 
sac. It grows through the micropyle and pushes into the embryo- 
sac between the cells which form a sheath around the micropylar 
. end of the sac. 
The nucellus is gradually absorbed during the development of 
the embryo-sac, and when the latter is mature the nucellar tissue 
entirely disappears from the micropylar end and from the sides, 
leaving these parts of the sac in immediate contact with the inner 
integument; ‘at the chalazal end of the sac, however, the nucellar 
tissue persists, its cells grow larger and become arranged in quite 
definite rows which seem to diverge from the point where the 
integuments arise from the nucellus. This tissue persists until, 
late in the history of the embryo-sac, it is finally absorbed. Ac- 
cording to Hegelmaier (1880), the nucellus in the ovule of Lupinus 
