8 
The Ohio Naturalist. 
[Vol. XIII, No. 1, 
cases there is only one. There is no difficulty in distinguishing 
the nucleoli from chromatin material since the safranin used in 
the combination stain gives the nucleoli a peculiar reddish tinge 
while chromatin material stains nearly black The nucleolus is 
in the middle of the nucleus, sometimes a little to one side; and 
on the periphery of the nucleus is the network and chromatin 
granules spoken of above. A little later the nucleus begins to 
swell very considerably, and gradually the network is loosened 
in one place or another from the nuclear wall. At this time the 
nucleolus is still in the middle of the nucleus. As the process 
continues the nucleus becomes larger and more of the threads 
becomes loosened from the wall (Figs. 6. 7. 8). 
At this stage the synizesis begins, the spirem massing together 
into an irregular lump which may or may not enclose the nucleolus. 
In some cases the nucleolus may be entirely separate from the 
synizetic knot. No division of the granules or longitudinal 
split of the spirem was observed. There is a well defined thread 
now present and in some cases loops of the thread could be seen 
sticking out from the opaque knot (Figs. 9 and 11). In other 
places little apparently free ends of the thread projected from the 
mass. On these threads defiinite chromatin granules were 
plainly visible and could easily be counted in any free loop. 
Whether the free ends represented natural breaks in the spirem 
or injuries caused by the contraction or the cutting, could of 
course, not be determined. But the appearance of the spirem 
before and after the synizesis indicates that the spirem is con¬ 
tinuous. The contracted chromatin mass was sometimes formed 
to one side of the nuclear cavity and sometimes in the middle 
(Figs. 9, 17). Sometimes it extended across the nucleus. There 
were various stages of contraction from the loosely coiled mass in 
which the threads were clearly visible (Fig. 11) to the tightly 
contracted mass in which no structure, whatsoever, could be made 
out. During older stages of the synizesis the knot is very much 
looser and the thread is much more complete and is thicker with 
the granules of a more uniform size. There is no question but 
that there has been a contraction of the chormatin, the mass 
occupying a much smaller area than before, while the nuclear 
cavity is much larger. Whether some of the enlargement of the 
nuclear cavity was due to plasmolizing reagents or entirely due 
to a normal growth could not be determined since there is consider¬ 
able difference in the size of various nuclei of apparently the same 
stage of development. 
Immediately after the synizesis the threads are delicate and 
contain numerous small granules. It is exceedingly difficult to 
follow the thread through all its convolution but in some cases it 
could be traced for quite a long distance (Figs, 12, 13, 14). There 
is generally one nucleolus at this stage but in some cases two are 
