49 
in the Root- Apex of Phaseohis. 
cell-wall now extends nearly all across the cell. The formative fibres are 
completely separated from the nuclei, and appear free in the cytoplasm 
at the periphery of the cell, as shown in Figs. 30 and 31. 
Fig. 31 shows a later stage of chromosome fusion. There are in each 
nucleus one large nucleolar mass, which has a form indicative of its production 
by the fusion of two smaller ones, and one or more smaller ones. In the 
upper nucleus one of the smaller nucleolar masses appears to be on the point 
of fusing with the larger. In both nuclei the large mass and one of the 
smaller ones is surrounded by a clear space. In all the cases of division 
figured, it is interesting to note that in each the two daughter-nuclei 
exhibit much the same conditions as regards fusion of the chromosomes, 
and are just in the same stage of development (Figs. 28-37). 
Fig. 32 figures a case in which the transverse cell-wall is completely 
formed. In the daughter-nuclei are to be seen two large nucleolar masses 
in the same stage of fusion, and two smaller masses. The nuclear network 
is also clear, but with very few chromatin-granules. 
In the next stage the fusion of the nucleolar masses is carried a step 
further (Fig. 33). In the lower nucleus there is one large nucleolus and near 
it are two smaller ones, of which one is just beginning to fuse with the 
large mass. The upper nucleus contains a single irregular nucleolus which 
has obviously just arisen by fusion with it of at least two smaller ones. 
I think we may consider, that the two prominent projections on it indicate 
the result of fusion of smaller masses with it. 
It is not always the case that the result of the nucleolar fusion leaves 
the nucleus with one large and one or more smaller nucleolar masses. 
In Fig. 34 we have a case in which there are three about equal-sized masses 
of nucleolar substance which are just beginning to fuse together. In 
all these cases a delicate nuclear network is visible in contact with the fusing 
nucleolar masses, and in Fig. 35 is shown an interesting case of an irregular 
mass of nucleolar substance connected at one point in a very prominent 
manner with the linin-network (cf. Fig. 5). 
When the nucleolar masses have become completely fused, the result- 
ing nucleolus is at first a homogeneous irregular body of uneven outline 
(Figs. 33 and 35), but it gradually becomes more or less spherical 
(Fig. 36), and finally its homogeneity disappears, and it becomes vesicular 
(Fig. 37). As this proceeds the nuclear network becomes restricted to the 
peripheral part of the nucleus (Figs. 36 and 37), but the nucleolus remains 
connected to it, as already mentioned, by delicate connecting threads 
(Figs. 1-5). 
During the time these changes are taking place, each nucleus gradually 
increases in size with the increase in size of the cell ; the nucleolus also 
adds to its bulk, and goes on growing until, having reached a certain stage 
of development, the nucleus again begins to divide. 
E 
