088 3Iarquette, Manifestations of polarity in plant cells which usw. 
is still finely distributed through tlie nuclear cavity, at the edges 
of tlie furrow, however, tlie granules are more closely crowded 
tlian elsewhere in tlie nucleus, a distribution such as would resült 
from tlie local indentation of a plastic vesicle which contains uni- 
formly distributed particles. 
The starcli body does not always press deeply into tlie resting 
nucleus, sometimes it merely lies closely against it withont indenting* 
it, and in these cases when tlie starcli body divides tlie two sepa- 
rating halves merely move along tlie surface of tlie nucleus. These 
cases are rarer, however, than tliose in which the nucleus is furrowed 
bv the separating daughter starcli bodies. 
After tlie starcli body lias completely divided into two, tlie 
lialves withdraw from eacli other until tliey lie at opposite poles 
of the elongated nucleus, close against its membrane, at the same 
time they change their shape or their position so that tlieir long 
axes now are at right angles to that of tlie nucleus (figs. 2 & 3). 
Frequently at this stage the cytoplasm between tlie starch bodies 
and the plasma membrane is more vacuolated and clearer than 
elsewhere in the cell. At about. this time tlie first indications of 
an approaching division become apparent in the nucleus itself, the 
chromatin begins to collect into larger aggregations. Frequently 
a more or less diagonal furrow which was formed by tlie starcli 
body pressing into the nucleus in the earlier stages is still to be 
seen at this stage. (Fig. 3.) Up to this time the chromatin 
appears in the finely divided condition characteristic of resting 
nuclei and it is plain that we have in these cells a long series 
of visible changes preparatory to cell division betöre the appear- 
ance of the chromatin gives anv indication of tlie beginning of 
the propliases; neither are there any fibers or rays visible in the 
cytoplasm up to this time. 
As the chromatin passes into tlie spirein stage 1 ), the polar 
structures leave the nuclear membrane, moving further apart from 
each other in opposite directions until frequently they lie close to 
the plasma-membrane. As they do so they become still more 
dattened and irregulär in outline. This irregularity of outline is 
wortliy of note for it is a further indication tliat the polar structure 
is not a vacuole whose form is determined by surface tension. As 
the polar structures move away from the nucleus, tlie cytoplasm 
between them and the plasma membrane assumes a denser appear- 
ance; if the amount of cytoplasm here present is small it lias 
this denser appearance throughout its extent. It almost looks as 
if the polar structures in moving away from tlie nucleus had 
pushed the cytoplasm ahead of them and thus crowded its elements 
b The formation of a continuous spirem has been questioned in recent vears. 
See Gtregoire and Wygaerts who worked on Trillium. La Cellnle (T. XXI. 
p. 5, 1904, and J. Kowalski who worked on Salamander larvae in Gregoire : s 
laboratory. La üellule (T. XXI. p. 349.) In the young leaf-cells of Isoetes a 
continuous spirem seems to be formed. I have not. however, devoted any 
special attention to determine whether possibly there are breaks in the apparently 
continuous spirem. 
