2 
The Ohio Naturalist. 
[Vol. VII, No. 1, 
The egg apparatus of Bursa is well organized and after fer¬ 
tilization the oospore elongates considerably and divides 
by a transverse wall into two cells of unequal size (Figs. 1—5). 
The basal cell does not divide again but begins to enlarge 
rapidly, finally developing into a large vesicular cell which is 
closely surrounded by the upper part of the wall of the ovule 
and continues in an active condition until the seed ripens. 
The upper cell divides by a transverse wall giving rise to a 
proembryo of three cells, the terminal cell, an intermediate 
cell, and the basal vesicular cell (Fig. 6). The next division is 
again transverse and probably takes place in the intermediate 
cell (Fig. 7). After a filament of four cells is produced, the apical 
or terminal embryo cell divides by a longitudinal wall, giving 
rise to the typical five-celled embryo (Fig. 8). The following 
division occurs in the suspensor cell next to the vesicular cell, 
resulting in a six-celled embryo with five tiers (Figs. 9-11). 
Often the cell below the two terminal embryo cells stains dark 
like them while the three suspensor cells take a much lighter 
stain (Figs. 10,11). This would indicate that this cell is the 
second cell of the embryo proper and that it does not contribute 
to the further development of the filamentous suspensor until 
its division at a much later stage. This point was, however, 
not determined. The two terminal cells now divide by longitu¬ 
dinal walls at right angles to the previous division giving rise to 
the terminal quadrants while further transverse divisions occur 
in the suspensor (Figs. 12-15). 
At the time when the terminal quadrants divide by transverse 
walls to form the octants, the suspensor usually consists of the 
vesicular cell and six intermediate cells (Figs. 16-20) and this is 
frequently the extent of this organ though more commonly there 
are seven or eight intermediate suspensor cells developed. The 
cotyledonary and hypocotvledonarv rgeions of the embryo are 
definitely separated by the divisions which give rise to the oc¬ 
tants. The octants soon cut off dermatogen cells by periclinal 
walls thus producing a nearly spherical body of sixteen cells 
(Figs. 17, 18). The periclinal divisions which give rise to the 
dermatogen appear first in the terminal octants (Fig. 17). At 
this stage the proembryo consists typically of twenty-two or 
twenty-three cells. While the dermatogen cells are continuing 
their divisions by anticlinal walls the eight inner cells divide by 
longitudinal walls and the cell between the suspensor proper and 
the terminal sphere divides by a transverse wall into the basal 
embryo cell and a very flat disk-like suspensor cell which takes 
no part in the development of the embryonic tissues (Fig. 19). 
The primary dermatogen begins its further development in 
the outer quadrants of cells and as would be expected the divi¬ 
sion in these cells is more active during the further growth of 
