268 BOTANICAL GAZETTE [APRIL 
distinct centrospheres preceding it as it passes through the tip 
of the tube. 
12. When the sperm nucleus passes out of the tube, the 
apex of the tube appears to soften, and the sperm nucleus, 
with its centrospheres, appears to break’ out abruptly, leaving a 
distinct opening in the tip of the tube, the edges of which often 
appear ragged; and from this perforation cytoplasm is seen to 
escape after the sperm nucleus. 
13. At the approach of the pollen tube the nucleus of the 
oosphere is greatly affected, being drawn out into a large bulge 
toward the approaching male cell. Sometimes two prominent 
centrospheres appear just on the top of this bulge. 
14. Centrospheres appear in resting nuclei and in division 
stages, and just before the contact and during the fusion of the 
two sexual nuclei two pairs of centrospheres appear, which seem 
to fuse simultaneously with the sex nuclei. 
15. The remaining synergid persists for a long time above 
and somewhat to one side of the vesicular suspensor cell, 
apparently in an active and healthy condition. 
16. After fertilization the oospore pushes downward and 
divides by a transverse wall. 
17. The second division of the pro-embryo is in the lower 
cell, also by a transverse wall. Of the three cells thus devel- 
oped in acropetal order, the uppermost cell never divides 
again, but enlarges greatly, forming the vesicular suspensor cell; 
the lowest develops into the cotyledon, while the middle cell 
gives rise, by an indefinite number of divisions in basipetal order, 
to the stem apex, hypocotyl, root tip, and a few suspensor cells. 
18. The cell divisions during the formation of the embryo do 
not occur in regular order, and though the succession of cells 
_ follows some general plan, there are frequently remarkable varia- 
tions mee must epimers change the whole course of devel- 
19. "The cotyledon i is first differentiated, and next the stem 
* which oo from a lateral hypodermal cell.in the first 
tier above the terminal cotyledon. a The heer) fo - 
i 
