10 ARISAEMA TRIPHYLLUM 
cavity, enlarge in size, and finally fuse near the chalazal end. 
That the nuclei always fuse seems certain from the examination of 
many preparations showing the nuclei in contact and in partial 
fusion. The idea is made more certain by the fact that no one of 
many preparations of past mature but sterile embryo-sacs ex- 
amined show free polar nuclei. A wide difference in the position 
of the nuclei at the time of fusion has been noted in a few cases. 
In one instance the contiguous nuclei were near the micropylar 
end, and in five cases they were near the middle of the embryo-sac. 
After the fusion of the polar nuclei the endosperm nucleus is 
almost universally found well down in the chalazal end of the 
cavity, being in some cases almost in contact with the antipodal 
cells. A remarkable exception was shown by one embryo-sac in 
which the fusion nucleus was close beside a synergid. 
The three antipodal nuclei sink close to the chalazal extremity 
of the sac, and are soon surrounded by cell walls (PLATE 1, FIG. 4). 
For a very short time they retain their appearance of living cells; 
but by the time fertilization takes place, they may be seen as 
shrunken, deeply staining masses pressed close in the chalazal 
extremity. With the activity of the vegetative nucleus in the 
residual cavity and the accompanying disorganization of the 
lower nucellar tissue, the antipodals entirely disappear. 
As stated in the former report (20, p. 233) a normal egg ap- 
paratus (PLATE I, FIG. 5) is formed. Some variations may be worth 
noting. The synergids sometimes show the principal vacuole 
above instead of below the nucleus. In some cases (PLATE I, FIG. 
3) synergids as large as the egg cell have been observed. A notice- 
able feature is the frequent occurrence of an egg cell reaching far 
down into the sac cavity (PLATE 1, FIG. 4). Inat least one case the 
egg nucleus was carried toa position near the center of the cavity. 
In two preparations from different plants embryo-sacs of mature 
dimensions were observed, with the primary endosperm nucleus 
and the shrunken antipodals expected in mature sacs, but showing 
instead of the normal egg apparatus, the three micropylar 
nuclei, each inclosed by a mass of protoplasm and a cell wall, 
floating free in a group in a cell cavity. The similarity of these 
cells suggests a question as to the primary difference between 
the synergids and the egg cell and as to what may bring about the 
final differentiation in the group. 
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