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Ethel M. Be r ridge. 
primary neck and central cells, and those which undergo a series of 
divisions, so that a row of jacket-cells is formed within it. These 
two sets of nuclei may he called respectively archegonium and 
jacket-cell initials; that they are very similar in character is evident 
from the strong likeness between the cells they give rise to, a like¬ 
ness worked out in detail in a previous paper on Ephedra distacliya (2), 
and much insisted upon by Dr. Porsch, who gives an excellent figure 
of egg-like jacket-cells. 
There must, however, be some slight difference determining 
which of the nuclei shall be archegonium and which jacket-cell 
initials, and an important consequence of this difference is that the 
egg-nuclei descended from the one set are capable of direct ferti¬ 
lization by sperm-nuclei, while the jacket-nuclei derived from the 
other set, if not actually incapable of direct fertilization, certainly 
never become fully-matured gametes. 
It is, nevertheless, a significant fact that in E. distacliya certain 
of these latter nuclei, under the stimulus imparted to the whole 
archegonial region by the entry of the pollen-tubes, and probably in 
all cases after fusion with another nucleus, show signs of proceeding 
to the formation of embryos. Within the jacket-cells themselves, 
where the stimulus from the pollen-tube must be slight and indirect 
it usually goes no further than the development of a radiating zone 
of cytoplasm round certain of the nuclei, but when the latter have 
escaped into the archegonium, or are only separated from it by an 
extremely thin wall, there is outgrowth of these pro-embryonal 
cells into primary suspensors occasionally bearing rudimentary 
embryos at the tip. That this potentiality is present in the jacket 
is demonstrated not only by the behaviour of these cells in E. 
distacliya , but is evidently clearly indicated in E. tri/urca, though it 
does not appear to reach such a degree of effective development 
here as in the European species. Dr. Land repeatedly remarks on 
the likeness of the jacket-cells to eggs, and says that “ Apogamy 
was at first suspected, but further study showed that these egg-like 
jacket-nuclei do not function, being finally broken down and absorbed 
by the pro-embryos.” Drs. Cavara and Rogasi also mention the 
formation of pro-embryos by jacket-nuclei in E. canipylopoda. The 
fusions preceding pro-embryo formation of this nature in E. 
distacliya are not always confined to jacket-nuclei, in several cases 
it was observed that the nucleus of an ordinary prothallial cell had 
entered a jacket-cell adjacent to it. Also in one case, represented 
in Eig. 17, fusion between a jacket-nucleus, and a nucleus from the 
