6o 
Sinnott. — The Morphology of the 
by a cytoplasmic sheath. The contents of the egg itself become much 
more dense and contain a few rather small vacuoles, but nothing corre- 
sponding to the large basal one of the other species. Dense angular bodies, 
probably protein in nature, are scattered through the cytoplasm. The wall 
of the egg is much thicker than in other members of the genus and is full 
of large sieve-like pits opposite the jacket cells. There are now two or three 
rows of the latter instead of only one. 
The act of fertilization was not observed, but the larger of the two male 
nuclei, which is surrounded by a cytoplasmic body and is doubtless functional, 
is about half the size of the egg nucleus. The figure of the first mitosis is 
very small, and occurs within the nucleus (Fig. 42), which now loses its 
membrane and becomes irregular in shape but remains in its original 
position until after the second mitosis. The four nuclei which result from 
this lie close together and surrounded by a sheath of dense cytoplasm drop 
slowly towards the bottom (Fig. 43), followed by much of the contents of the 
egg. Above them develops a large vacuole (Fig. 44), separating the basal, 
proembryonic region of the archegonium from its upper sterile portion. 
Nuclei often are present in this upper part, and though some of them may 
perhaps be derived from the ventral canal or second male nuclei, it seems 
much more likely that they are all jacket-cell nuclei, for these are often 
seen breaking through into the archegonium as it begins to go to pieces. 
The four nuclei of the proembryo now divide and eventually give rise 
to about sixteen, which are crowded irregularly into the very narrow base 
of the archegonium (PI. IX, Fig. 45). At this time walls are first formed. 
Some of the cells immediately undergo division, and the regular number and 
arrangement found in the proembryos of other species is not observable here. 
The rosette tier is very poorly developed, and almost immediately goes to 
pieces. The suspensors are usually nine in number and often cut off cells 
from their upper ends. The embryogenous tier consists not only of a large 
binucleate terminal cell, as in the other members of the genus, but of a group 
of cells between it and the suspensors. This group is small at first, but its 
members immediately begin to divide, and in P. spicatus may number from 
twenty to forty before the suspensors elongate to any extent (Fig. 46). In 
P . ferrugineus there are rarely more than eight or twelve cells in this tier 
(Fig. 47) until it has been pushed far into the endosperm. In the former 
species, the terminal cell, long, pointed, and often serving for a time as 
a protecting cap, is usually sloughed off. In P . ferrugineus the apical cell 
is blunter, but is provided with a thickened tip and almost always persists. 
The embryos show no signs of budding and are forced far down into the sac, 
where they begin a rapid growth. The later development of the embryo 
could not be followed, but it doubtless becomes dicotyledonous, as in the rest 
of the family. Starch is laid down in the axial region immediately after 
fertilization and is soon deposited throughout the whole endosperm. 
