212 
IOWA ACADEMY OE SCIENCES. 
droop probably depends on the way the flower hangs. 
This trouble begins about the time of formation of macro- 
spores, and especially about the time of fertilization. In 
staining no attempt was made to obtain nuclear results in 
the way of karyokinetic figures, because of the extreme 
smallness of the cells. Only the most common stains 
were used, either Delafield’s hsematoxylon or a combina- 
tion stain of eosin and haematoxylon. In all, about 500 
flowers were sectioned, but only a few of this number were 
of any value, because so many were cut obliquely. 
As soon as the leaf which forms the pistil has folded 
together, there is a proliferation of cells on either side of 
the suture formed by the fusion of the two edges of the 
leaf. As a result of the increased number of cells in this 
region, the nucellus is produced (Fig. 2) and soon becomes a 
prominent protrusion into the cavity of the pistil. 
In the apical region of the nucellus one of the hvpoder- 
mal cells undergoes marked differentiation. It increases 
greatly in size, becomes granular, and has a large nucleus. 
At about the time of the formation of the archisporial 
cell, the integuments are first making their appearance, 
the inner one appearing slightly before the outer one 
(Fig. 8), 
The archisporial cell divides into two, and each of the 
resulting cells divides again, instead of two or three cells 
being cut off the tapetal end of the first cell formed, as is 
frequently the case. The presence of two nuclei in each 
archisporium (Fig. 5) in the two-celled stage, and the posi- 
tion of the cells in the four-celled stage (Fig. 6) indicates 
that each of the first two cells formed divides again. It is 
the lower cell of the ‘row of four which develops into a 
macrospore at the expense of the other three (Fig. 7). 
After the first division of. the nucleus of the embryo sac, 
and about the time or just before the fusion of the two 
nuclei which form the definetive nucleus, cell walls are 
formed around the antipodal cells (Fig. 12). The form of 
the antipodals is generally triangular. Concerning the 
position of the egg apparatus, it may be at one side of 
both synergids or below them Figs. 12, 18). The mature 
