196 BOTANICAL GAZETTE [MARCH 
can be of no significance in the distribution of the chromatin, 
as each chromosome is yet a tubular structure resulting from the 
fusion of the tetrads, unaffected by the breaking of the spireme. 
After the nuclear membrane has become dissolved and the 
interchange of material between nucleus and cytoplasm is com- 
plete, the rings of chromatin split, causing the separation of the 
associated chromatin masses. figs. 32 and 37 show stages 
where the separation of the associated chromatin masses is well 
under way, while fig. 37 shows a similar stage where some of 
the segments have been cut crosswise. The pairs of chromatin 
threads separate first from each other at the middle, while the 
ends may remain for some time attached. 
In cells shown in figs. 372, 38, we have the last stages in the 
separation of the chromosomes in the spireme segment. The 
ends of the chromosomes are still connected by the linin sub- 
stance, though the separation is nearly complete. The structure 
of each chromosome at this stage, as seen both in surface view 
and in cross section, presents exactly the same appearance as 
that of the mother segment of the spireme, the only difference 
being that of size. After the splitting the chromatin closes up 
to form again the rings, thus making the tubular structure of © 
the daughter chromosomes of the spireme. The end of each 
chromosome shows the ring formed of chromatin masses, the 
margin becoming indefinitely four-sided; the surface view gives 
the same vacuolar or longitudinally split appearance throughout 
their length. Fig. 38 is of a stage showing the beginning of 
their movement toward the poles. The ring-like form, as seen 
from the end, and the split or vacuolar appearance, as seen in 
surface views, are here clearly marked, while in fig. ¢z the com- 
ponent tetrads can be traced. In fig. 39 the cell was cut in such 
a plane as to give a longitudinal section of the chromosomes at 
one pole of the diaster and a cross section at the other pole. It 
can thus be seen from these figures that the disintegration of the 
rings into tetrads proceeds with the drawing apart of the chromo- 
somes and with the beginning of their passage toward the poles. 
The chromosomes having arrived at the poles become coiled, 
while their ends begin to approach one another. Figs. 42-45 
