6x6 Price*— Some Studies on the Structure of the Plant Cell 
of the membrane may be due to the difference in refractive index between 
this and the nuclear plasma. 
On fixation with glacial acetic acid the whole nuclear mass becomes 
milky at first, while the nucleolus is more rapidly affected and becomes 
slightly more distinct. The movement of particles on the outside of the 
nucleus ceases almost at once. After complete fixation the nucleolar 
membrane becomes even more distinct. 
In the cells of Etodea the nucleus is present generally as a rather 
flattened ellipsoidal mass in the layer of protoplasm which lines the cell- 
wall. It is best observed in the edge cells, but when against the dorsal or 
ventral walls of the cell (according as one side or the other is under ob- 
servation) it may often be quite well seen as a circular mass in practically 
any cell of the leaf. Starvation of the leaves, with the consequent diminution 
in size of the chloroplasts and their migration to the side walls already 
described, often facilitates the observation of the nucleus in this case. 
The nucleus here, whether ellipsoidal or spherical in form, is only 
slightly milky in appearance, with apparently a hydrogel structure as before 
(see PI. XLI, Fig. 8). The overlying cytoplasm is often small in amount, but 
the minute particles in the protoplasmic stream can be seen constantly 
flowing past the nucleus. As far as could be made out, these nuclei in the 
resting stage showed no further sign of organized structure, not even 
a nucleolus, and were almost homogeneous throughout. 
The effect of fixation is very marked. The nuclear substance, although 
with the appearance of a hydrogel before, undergoes a marked change. It 
rapidly becomes almost opaque (PL XLI, Fig. 9), and assumes a mottled 
structure with fairly large diffraction images. This is, in fact, the general 
type of image presented by a regularly coagulated gel of fairly coarse 
structure. A further discussion of the nature of the change between the 
two gel states will be given when dealing with the fixation of the cell 
colloids. The nuclear colloid is much more opaque and of coarser structure 
than the cytoplasm after fixation. 
In some cases after fixation, a structure which corresponds to a 
nucleolus can be seen. 
In some respects the nuclear structures described agree to a certain 
extent with those observed by Faure-Fremiet (TO) in the nuclei of certain 
Protozoa, an almost homogeneous but nebulous structure in the living state, 
with, however, in his case a nucleolus and some ‘globules basophiles \ 
Action of dilute alkalis causes the structure to clear, and the nucleolus and 
globules become more distinct, and this condition is to a certain extent 
reversible. 
No such changes have, however, been observed in the plant cell. 
On the whole, the facts brought forward hardly throw any new light 
on the structure of the nucleus from the general cytological point of view. 
