440 
The Ohio Naturalist. 
[Vol. Ill, No. 8, 
must be regarded as being bilocular. The related plants, of the 
Alismaceae and Naiadaceae, as well as the Vallisneriaceae, are 
described by Britton and Brown as having two celled anthers. 
Fig. 9 shows the mierosporocytes in the pollen sacs. Before the 
pollen is shed the grains are three-celled, having a large tulre 
nucleus and two smaller male cells (Fig. io). 
The young ovule has two integuments ; the inner one is barely 
beginning to appear when the archesporial cell is organized 
(Fig. i) The archesporial cell is hypodermal in origin. From 
this a tapetal cell is cut off and this divides into two (Figs. 2 
and 3). The megasporccyte enlarges and four megaspores are 
finally produced by two transverse divisions, although in some 
cases some of the walls may be oblique (Figs. 4 and 3). The 
functional megaspore, which is the lowest, divides into two cells, 
forming the two celled embryo-sac in the usual way (Fig. 6) ; 
one cell passes to the upper and the other to the lower end of the 
sac and by successive divisions the typical eight-celled embryo- 
sac is firmed (Fig. 7). The polar nuclei are rather large and 
they conjugate in about the middle of the sac. A large number 
of these conjugations was observed, but there was no trace of a 
triple conjugation of polar nuclei and a male cell. The syner- 
giclae lie side by side, extending across the upper end of the 
sac, and beneath them is the oosphere. The antipodals have the 
same relative position in the lower end that the egg-apparatus 
has in the upper end. 
At the first division of the definitive nucleus two cells are 
formed with a transverse wall across the sac between them. The 
upper one of these by further division forms a small amount of 
endosperm tissue. The lower one develops into a large vesicular 
cell with a large nucleus (Fig. 8). This same structure with 
the partition wall was found by Schaffner in Sagittaria , by Cook 
in Castalia and Nymp/iaca , and by Murbeck in Ruppia. It has 
also been found in other groups. Contrary to the case in Sagit- 
taria, no direct division of this nuclues was observed. At this 
stage the antipodals are in a pocket at the base of the sac, where 
they persist for a long time. 
The first division of the oospore is transverse. The lower cell 
elongates and divides transversely also, forming the first three 
cells of the proembryo (Fig. 11). The upper one of these 
does not divide but forms a very large suspensor cell as is usual 
in the Helobiae. The next division is in the middle cell and is 
also transverse. There is now a tier of four cells. The lowest 
one of the tier divides longitudinally (Fig. 12), and following 
this division there is a transverse division in the cell next to the 
large suspensor cell followed by another longitudinal division in 
the lowest tier and one in the tier above (Fig. 13). At this 
stage the pro-embryo is composed of nine cells arranged in five 
