74 Wager and Peniston.—Cytological Observations on 
gentian violet, by which the nucleolus, surrounded by the irregular mass of 
chromatin granules, can be differentiated. An appearance commonly 
observed at this stage is a group of strongly stained chromatin granules, 
more or less radially arranged around the nucleolus. Sometimes a nucleolus 
is seen with a single strand only of the chromatin network attached to 
it. Then the chromatin granules begin to disappear. The cytoplasm 
in the immediate neighbourhood of the nucleolus becomes more deeply 
stained, and, together with the less deeply stained peripheral portion, 
exhibits a beautiful alveolar structure. 
We are unable to confirm the account given by Wager (’ 98 ) of the 
division of the nuclear vacuole first of all into two, ‘ then probably by 
further division into numerous smaller portions, until finally a delicate 
foam structure of the protoplasm is produced.’ Repeated careful examina¬ 
tion both of living and of stained preparations failed to reveal any satis¬ 
factory evidence for this, and we are inclined to agree with Guilliermond (’ 02 ) 
that the foam structure is due to the increase in the number of volutin 
(metachromatin) granules which appear in large numbers round the 
nucleolus, and to glycogen vacuoles which occur more especially at the 
periphery. Whether the foam structure is due to the repeated subdivision 
of pre-existing volutin and glycogen vacuoles we cannot say, but we are 
inclined to think that in the case of the volutin it is largely due to the 
formation of granules de novo from material which is suddenly made 
available in the cell. 
The presence of volutin granules in the nuclear vacuole, and their 
appearance often in close contact with it and the nucleolus, indicates that 
they may be products of the nuclear activity. In the Cyanophyceae they also 
occur in the nucleus (central body). It is quite possible therefore that 
the large increase in the volutin at the time the nuclear vacuole disappears 
may be the result of the formative activity of the chromatin granules then 
set free. At a later stage the volutin grains seem to dissolve, and there 
is reason to believe that they are finally used up in the formation of the 
spores, and especially of the spore walls. 
The nucleolus has meanwhile increased in size, but shows a less 
marked staining capacity, and a deeply stained granular mass in contact 
with it now becomes visible. This appears to be similar to that already 
described and figured (Figs. 53, 54, 56, &c.), but is larger and seems to be 
more deeply embedded in the nucleolus. This differentiation, however, 
is observed only when the stain has been well washed out. In nor¬ 
mally stained specimens which have not been so well washed out, it can 
be seen that at the periphery of the nucleolus there is a granular chro¬ 
matin layer in close contact with it. Immediately around this is the 
deeply stainable sporogenous cytoplasm which takes part in the formation 
of the spores. 
