344 BOTANICAL GAZETTE [NOVEMBER 
Except at its apex, the structure of the gametophyte is like that shown 
in this figure, a single layer of small peripheral cells being succeeded 
by layers of larger and larger cells. At the apex, where the arche- 
gonial initials are appearing, the single layer of small cells broadens 
rapidly into a lenticular group, from 7-10 cells in thickness. This 
group consists of about 200 cells, which are considerably smaller than 
those of the peripheral layer, as may be seen by comparing jigs. 19 
and 23, which are drawn to the same scale. The archegonium initials 
may be seen at the periphery of this group. At this stage, the cells 
of the gametophyte contain no starch or other food stuffs, the only 
visible contents being the nucleus, a scanty amount of cytoplasm, and 
the transparent cell sap. 
Three weeks later, when the endosperm has reached a length 
of 15™, the cell contents seem to be just the same as before, no 
accumulation of foodstuffs being visible. Cell division has progressed 
rapidly, so that the row of four cells shown in fig. 19, a, is now repre- 
sented by the two rows (sixteen cells) of fig. 20, a. Sections of the 
endosperm 4™™ thick, fixed in Flemming’s solution early in December, 
appear somewhat darker in the region of the archegonia. In the 
chalazal region there is also a slightly darker color. Microtome sec- 
tions show that the color is due in part to occasional grains of starch, 
but more particularly to small globules, probably oil, which stain 
black with osmic acid. The fact that the cells are considerably 
smaller in the archegonial region also makes the endosperm appeat 
denser at this place. In the ripe seed the gametophyte shows con- - 
siderable differentiation (fig. 21). The cells of the peripheral layer 
are small, rich in protoplasm, and contain numerous very minute 
starch grains. This layer contrasts sharply with the next, the cells of 
which are much larger and contain larger starch grains. This second 
layer is in turn fairly well marked off from the rest of the gametophyte, 
which consists of still larger cells densely packed with large starch 
grains. Numerous isolated cells containing tannin form a broad zone 
midway. between the center and periphery of the endosperm. The 
tannin is much more abundant in the upper part of the gametophyte. 
Development oj archegonia—Probably all of the superficial cells 
of the group at the apex of the endosperm are potentially arche- 
gonium initials. The number of archegonia varies from none at 
