366 DUNCAN S. JOHNSON 
apparently plays only a minor part in connection with the divisions of 
the nucleus and cell (figs. 60, 62, 63, 64). The inner layer of cyto- 
plasm is but slightly vacuolated, is densely granular, stains darkly and 
becomes highly active at the time of nuclear division. This is in- 
dicated by the numerous strands and fibers formed in it (figs. 63, 65, 
67, 68, 70). With the growth of the embryo sac, after the disap- 
pearance of the cell walls between the first four nuclei, this differ- 
entiation of the cytoplasm becomes gradually less marked (figs. 73, 74) 
and with the increased vacuolation of the eight-nucleate sac this dif- 
ferentiation of the cytoplasm becomes scarcely discernible (figs. 76, 77). 
When, however, in the sixteen-nucleate sac, the egg and synergid 
nuclei are * cut off, and the endosperm-forming nuclei are grouped 
closely together, the cytoplasm about the egg and synergids and about 
the group of endosperm nuclei again becomes denser (figs. 84, 88). 
At no later time, however, does it show evidence of the extreme ac- 
tivity seen during the two reduction divisions. When the mitotic 
figure is organized in the embryo sac mother-cell, after the occurence 
of the process of synapsis and chromosome-formation described above, 
the axis of the spindle may be either longitudinal or transverse to the 
ovule (figs. 65, 66). This spindle is bipolar at the earliest stage seen, 
acute at the poles and about 15 /x long by 10 /z across. The chro- 
mosomes are more or less bent rods, only about twice as long as thick, 
and are about 12 or 14 in number. In the later anaphase the chro- 
mosomes are seen to be somewhat angular but nearly isodimensional. 
They then measure i to 1.5 in diameter and each has attached to 
the side turned toward the pole a bundle of smaller fibrils (fig. 65). 
The daughter nuclei from the first division are apparently organ- 
ized very promptly after the chromosomes reach the poles. These 
nuclei are 7 or 8 in diameter, i. e., about half as large as the parent 
nucleus in late synapsis. The chromatin of the daughter nucleus, at 
the time the new wall is first developed, has the form of a series of more 
than 12 rather angular granules. These deeply staining granules lie 
near the nuclear wall and are more or less connected by faintly colored 
strands (fig. 67). Before the nuclear wall breaks down, in preparation 
for the second division, the chromatin assumes a more uniformly 
thread-like arrangement and, though larger granules are still evident 
the meshes become more numerous and regular (fig. 68). A cell plate 
is often, perhaps always, formed on the spindle between these two 
nuclei (fig. 67). 
