1895. J The Embryo-Sac of Aster. 209 
lium proves its title to the name by bearing archegonia. The 
bearing of archegonia would vindicate the claim of the antip- 
odal cells in the same manner, but my reading has failed to 
furnish a single instance of such a phenomenon. A glance 
at my figures will show that the antipodal cells are not all 
alike, the lower one sometimes differing decidedly from the 
others. It is often much larger than the rest, it differs in the 
density of its protoplasm, appearing as if it had increased 
much more rapidly in size than in substance, and its nuclei 
resemble the endosperm-nucleus rather than the nuclei of the 
other antipodal cells. Figs. 1, 2, and 3 illustrate various 
forms of this cell with its large nuclei. The behavior of this 
cell recalls the free cell formation which occurs in the early 
history of the macrospore. This antipodal growth breaks 
through the layer of tapetal cells which surrounds the embryo- 
Sac, and, continuing its development sometimes to an extent 
equalling half the original length of the sac, exerts a des- 
tructive effect upon the cells of the adjacent tissues. The 
mere tendency toward further development manifested by the 
antipodal cells is worthy of careful consideration. 
desire to call particular attention to the lower cell in fig. 
3. I feel. positive that I have discovered in this cell a veri- 
table odsphere. It has precisely the appearance of the or- 
dinary odspheres of Aster Nove-Anglia, even to the posi- 
tion of its nucleus and vacuole and the distribution of its pro- 
toplasm. Furthermore, it has no cell membrane, thus differ- 
ing in another important particular from the usual antipodal 
cell. It would seem that after the nucleus had divided, one of 
the daughter-nuclei had surrounded itself with protoplasm 
and become free, just as the ordinary odsphere originates and 
separates itself from the surrounding protoplasm of the macro- 
Spore. The fact that nuclei of other antipodal cells sometimes 
surround themselves with protoplasm in a way which recalls 
the formation of the ordinary odsphere, makes this theory 
seem possible. Figs. 2 and 6, x, furnish examples of such 
nuclei. It might be suggested that we have here a macro- 
Spore, in an unusual position, but a macrospore nevertheless. 
Whatever its real nature may be, its origin is not so un- 
certain. In some slides, the septum proves that this cell 
arises from division; in others, it may be one of the three 
original antipodal cells. In any case, its origin is not that 
of the macrospore, but that of the antipodal cell. The ap- 
14~—Vol. XX.—No, 5. 
