July, 1922] 
CLELAND OENOTHERA FRANCISCANA 
395 
fact I am not prepared to say. The question naturally arises, however, 
as to whether such a position might not be due to strong exosmotic currents 
which would pull the reticulum toward that side of the nucleus first affected 
by the fixing fluid. If it be true that the position of the knot is due to 
the action of the fixing fluid, one might perhaps be justified in harboring 
slight suspicions as to the cause of the shrinkage itself. 
In early synizesis the whole reticulum is so massed together and the 
individual threads are so fine that it is almost impossible to distinguish 
anything in detail. The only way really to observe what is taking place 
is to study thin tangential sections of the knot. We are in this way enabled 
to see that the same process which was going on just previous to synizesis, 
by which certain threads were being absorbed while others were becoming 
enlarged, is still in progress. The network is at first much like that which 
entered synizesis, except that the meshes have become smaller by con- 
traction, and the whole has thus become much more compact (figs. 5-7). 
The threads, however, rapidly become less and less uniform in appearance, 
as certain of them give up their contents to others (fig. 6). As the result 
of this process, some of the threads begin to stand out more and more 
prominently, so that, as later and later stages are reached, it becomes 
apparent to one examining the knot as a whole that it is reticulate in 
nature. One can distinguish threads running here and there throughout 
the densely packed mass. Tangential sections of late stages show that 
the finer threads are fast disappearing and that those which remain are 
becoming not only more prominent, but on the whole more uniform in 
diameter and less granular (figs. 8-10). 
Certain of the threads in the center of the reticulum, and often in 
close juxtaposition with the nucleolus, may in time become especially 
prominent (PI. XXV, figs. 9-12; PI. XXVI, fig. 13). They swell greatly 
and evidently come to contain a great deal of chromatin material. A 
whole section of the network may become thus involved, with the result 
that a large, more or less shapeless body is formed in the middle of the 
reticulum. The nearness of this mass to the nucleolus suggests that the 
latter may be emptying itself of its chromatin contents, the rate of emptying 
being greater than the rate at which it can flow out into the various parts 
of the reticulum. These aggregations disappear more or less completely 
by the beginning of the open spireme stage (fig. 14). 
During late synizesis the spireme becomes continually clearer and more 
uniform, as the threads which are not to survive disappear and their mate- 
rial, and that from the nucleolus, becomes more evenly spread over the 
thread system (PI. XXV, figs. 8-10). While the surviving threads are 
much thicker than those of the pre-synizetic reticulum, they do not con- 
tinue to thicken indefinitely. Instead, they lengthen considerably to make 
room for the additional chromatin material. This lengthening process may 
very well be the cause of the unfolding of the tangled knot. A reticulum 
