Shaw. — The Fertilization of O hoc lea. 279 
condition. This makes it impossible to say without further 
study what is the rate of normal 4iuclear fusion. Among 
the few early stages of O. Struthiopteris that were sec- 
tioned and successfully stained, one after two days showed 
the male nucleus but little further advanced than that of 
Fig. 14, which was killed after thirty-six hours. Another 
egg of that species contained, after three days, a nucleus 
which had slightly enlarged but contained nothing that could 
be identified as male chromatin, although there were outside 
of this egg the crowded remains of free spermatozoids which 
must have entered the venter when the canal was open and 
the egg in a receptive condition. So it appears that after 
three days the nuclear fusion may be complete. 
The cytoplasm of the egg becomes vacuolated as the cell 
becomes turgid, and may after a time be pretty evenly 
distributed around the lumen (Fig. 11) ; or it may be denser 
on two sides of the nucleus (Fig. 4). In the material stained 
with alum-cochineal and Delafield’s haematoxylin, the cyto- 
plasm appeared to be composed mainly of spherical bodies. 
But in the beautiful alum-carmine preparations the cytoplasm, 
although very slightly stained, showed, with the most favour- 
able illumination, a reticular or alveolar structure resembling 
that of the nuclear network, but with larger meshes. This was 
not exhibited distinctly enough to be represented in the 
drawing. No centrosome or radiations, such as are formed 
about one, were seen in the egg-cytoplasm. 
In most of the eggs that are fertilized the protoplasm 
decreases in quantity after two or three days, and retreats 
to the inner side of the venter with the nucleus, which 
becomes smaller. Whether any such as these afterward 
divide is not known. A large proportion of the fertilized 
eggs never divide. It might be supposed that the rather 
peculiar treatment of the prothallia in these experiments 
was responsible not only for an increase in the proportion 
of sterile eggs, but also for a wider variation in the rate of 
nuclear fusion. Opposed to such a supposition is the fact 
that many of the prothallia left on water showed more 
U 2 
