Marquette, Manifestations of polarity in plant cells wliich usw. 287 
lias its explanantion partly in the fact that different leaves vary 
in the amount of starcli tliey carry, and furthermore, tliat the 
starcli is not uniformly distributed throughout a whole leaf. Not 
rarely there are cells whicli contain no starcli at all, but in 
them this peculiar body is none the less present, It is merely 
not so conspicuous as when it contains deeply staining starcli 
grains. While these variations in the starch content of different 
leaves make difficult a final jndgment as to whether the amount 
of starch in any particular cell varies witli its condition of devel¬ 
opment, it seems none the less as if the starch content of the 
individual cells undergoes periodical changes parallel with the 
karvokinetic cycle. 
«y «y 
More important than the variations in the amount of starch 
contained in these structures are the changes in shape and in 
Position whicli they undergo and whicli upon closer examination 
are seen to be in intimate relation with the processes of nuclear 
division. As was stated above, there are invariablv either one 
or two of these structures in a cell, and examination sliows tliat 
whether one or two are present depends upon the condition of the 
cell with respect to division. 
Immediately after cell division, eacli daughter cell invariablv 
contains a single starch mass, and this condition continues also in 
the completelv reconstructed and so-called „resting“ cell. In such 
cells tlie starcli-bodv lies close to one side of the nucleus, in most 
cases presses into it so tliat the nucleus is deeply indented. (Fig. 1.) 
The shape of the starch body varies considerably. Frequently it 
is fairly well rounded, but at other times is more elongated as in 
Fig. 1, here it is seen extending out from the polar depression in 
the nucleus, bending to one side and running along closely pressed 
to the nucleus for some distance. By focusing deeper down into 
the section it can be seen that the starch body also extends 
beyond the polar depression of the nucleus on its under side, 
spreading out somewhat into the cytoplasm. In this figure, as 
always, the polar indentation in the nucleus is on the side opposite 
the newty formed cell wall. 
In the young leaves of Isoetes cell divisions follow rapidly 
one upon the otlier so that there is some difficulty in deciding 
whether a cell is in a perfectly „resting“ condition or whether the 
prophases of the next division are already in progress. The 
most' characteristic indication of an approaching cell division is 
that the single starch body of the „resting“ cell divides into two. 
Stages showing the division of this body are sharply marked and 
not difficult to find. The body elongates and at the same time it 
constricts in its middle portion until finally it separates into two. 
While tllis is going on the starch body maintains its close contact 
with the nucleus. • In fact it is so pressed into the nucleus tliat 
a furrow is formed in the surface of the latter through whicli the 
separating halves of the starch body draw apart, at the same time 
the nucleus is also elongatfid in the direction of the Separation of 
the daughter starch bodies. (Fig. 2.) The chromatin at this stage 
