344° BOTANICAL GAZETTE [MAY 
first and second synergids seem to have been cut off successively 
from the mother nucleus of the egg. The synergids disappear 
almost immediately. A similar irregularity was found in the 
antipodals.”” This could not be verified in P. natans, in which 
the process seems quite normal (figs. 73,74, 77). At this time 
there is considerable plasmolysis even when great care is taken 
in the fixing and subsequent processes (jigs. 75, 16, 77). In fig. 
4 traces of the first spindle of the megaspore can still be seen 
connecting the recently formed daughter nuclei, but there is no 
trace of a wall. By the growth of the sac the antipodals are 
left ina small pocket, and are of short duration (jigs. 16, 77); 
but no traces of a wall shutting them off from the rest of the 
sac. at any time could be found. Nor could a wall be found 
cutting off the egg-apparatus from the opposite end of the sac. 
The polar nuclei never meet in the center of the sac, but always 
nearer the antipodal end (figs. 76, 17). The endosperm 
develops as a parietal layer of cytoplasm in which free nuclei 
are imbedded, and no walls were observed in the most advanced 
stages studied (figs. 19, 21d). 
THE EMBRYO. 
The first division of the oospore is transverse, resulting ina 
_ large vesicular suspensor cell and the first cell of the embryo 
proper (fig. 78). The three-celled embryo shown (fig. 79) has 
probably resulted from the division of the embryo cell. The 
single suspensor cell becomes remarkably large and vesicular, and 
its nucleus and nucleolus correspond in size. The first division of 
the terminal cell in the row of three is longitudinal (jig. 20), 
and this is followed by a second longitudinal division at right 
angles to the first (fig. 27). This quadrant stage is also shown 
in transverse section in fig. 27d. Further views of the embryo 
at this period are shown in figs. 2ra—21d, which are consecutive 
transverse sections from such an embryo as that shown in jig. 
21, in which figure the points at which the sections are made 
are lettered a, 6,c,d. It is seen from the sections that the 
young embryo is cylindrical rather than flattened. 

