86 BOTANICAL GAZETTE [avcusr 
After the formation of the cross wall, the arrangement of the cell 
contents becomes more regular. The oogonium increases rapidly in 
size, and the peripheral layer of protoplasm grows proportionally — 
thinner. The strands and films of protoplasm that before crossed 
the oogonium irregularly become arranged so that there is a gradual 
accumulation of the protoplasm in the center of the -celly held in 
position by delicate strands which pass to the periphery, and the 
surviving nucleus always lies within this region. Figs. 10-12 illus- 
trate these conditions as they appear in thin sections (5 #), but they 
cannot show the numerous radiating strands that hold the central 
mass in place. The degenerating nuclei lie chiefly in the peripheral 
layer of protoplasm, but some may always be found in the larger 
strands that enter the interior of the oogonium. 
Although I have not been able to find any morphological evidence 
which would indicate that this accumulation of protoplasm is a 
dynamic center of the cell, there are good reasons for thinking that 
it really is such. The surviving nucleus of the oogonium is always 
found in this central mass surrounded by plastids and deeply stain- ‘ 
ing granular protoplasm, which suggests material of a trophoplasmic 
nature. The peripheral protoplasm forms a thin layer under the 
cell wall in which one may find for a long time traces of the other 
nuclei that have degenerated. F igs. 10 and 11 show some of these 
nuclei (d) so far reduced that there is nothing left but a deeply stained 
(with safranin) globule of nucleolar material apparently lying free 
in the protoplasm. No one would relate these structures to nuclei 
unless he had followed their history through the process of degen 
eration, for they are soon reduced almost beyond the point of recog: 
nition. But at this time the surviving nucleus (fig. 10) near the center 
of the oogonium increases rapidly in size until in the mature ¢&8 
(fig. 11) it is three or four times as large as the original nuclei in 
young oogonia. The inference is plain that the central region of 
the oogonium is a much more favorable situation for nuclear growth 
and activities than at the periphery. 
- For this reason the author considers the dense central mass of 
protoplasm as comparable to the region of the egg in Saprolegnia 
and the Peronosporales which is dominated by the coenocentrum: 
It is apparently the region of the cell most favorable for nuclear 
