PTERIDOPHYTA. Iq] 
the oval surface of the receptive spot, but had not penetrated the 
plasma membrane. It had apparently untwisted and had begun to 
reticulate, as its structure was somewhat granular or lumpy in appear- 
ance. In still another instance the spermatozoid had just passed 
through the plasma membrane at the receptive spot. The egg was 
not collapsed, but quite turgid. The receptive spot was distinguished 
from the rest of the cytoplasm only by the presence of fewer granules 
and, perhaps, a little looser reticulum. Other eggs were observed in 
a turgid condition (the archegonium being open), into which no sper- 
matozoid had penetrated, but the nucleus was concave on the upper 
side. It may be mentioned that the nucleus is not always concave, 
but may be rounded or globular. Apart from these instances the 
observations of the author agree with those of Shaw, 
In about one-half hour, or less, after the entrance of the spermato- 
zoid into the archegonium, the canal is closed by the expansion of the 
four proximal neck-cells and the four just beyond them. The egg 
recovers its turgidity and forces the free spermatozoids against the 
outer wall of the venter (Fig. 56, D). A cellulose membrane does not 
seem to be formed about the egg immediately, although, as stated by 
Shaw, a very delicate cellulose wall may have been dissolved by the 
chromic acid used in fixing. Soon after penetrating the egg the nucleus 
of the spermatozoid enters the egg-nucleus ‘before undergoing any 
change in form or visible structure (Fig. 55, B). The fate of the 
cytoplasmic part was not very satisfactorily followed, but all the facts 
observed indicate that the cytoplasmic band and blepharoplast are left 
in the cytoplasm of the egg, where, as in Cycas and Zaméa of the 
Gymnosperms, they are absorbed. In Fig. 56, D, a body lying near 
the concave side of the nucleus bears some resemblance to the cyto- 
plasmic part of the spermatozoid. The author has also observed in 
several instances undoubted traces of the blepharoplast near the upper 
surface of the nucleus, and there is no question but that the fate of 
the blepharoplast and cytoplasm is as just stated. 
The egg-nucleus during the entire process of fecundation is in the 
resting condition. Several conspicuous nucleoli are usually present. 
They vary in size and have a vacuolate structure. In the delicate linin 
network are distributed the small chromatin granules. 
In a short time the sperm-nucleus within the egg-nucleus begins to 
reticulate, becoming visibly granular and of a looser structure. This 
is apparent three hours after the entrance of the spermatozoid into the 
archegonium (Fig. 56, D), but it may sometimes be seen earlier, after 
thirty minutes or one hour. The time after which a change is notice- 
