1908] GATES—REDUCTION IN OENOTHERA 9 
same condition is observed during synapsis, which is found in the 
same sections. In places the nuclear membrane has either disap- 
peared or is too delicate to be observed. The cytoplasm, however, 
retains the original outline of the nucleus. Morrier (20) has 
apparently observed similar conditions of the nuclear membrane at 
this time. In some cases it is ruptured and a portion of it is actually 
carried inward with the nuclear reticulum at the beginning of the 
' contraction (fig. 12). One is tempted to explain this as an artifact; 
but that this is not the explanation is shown by the considerations 
already mentioned. The explanation appears to be that as contrac- 
tion proceeds a portion of the nuclear membrane may be torn away 
and carried inward attached to the threads. Frequently in these 
stages one finds the nuclear membrane present on one side of the 
nucleus but invisible elsewhere. This is the case in fig. 12, although 
the membrane was drawn as though complete. Observations of other 
nuclei bear out this interpretation, the nuclear membrane being clearly 
visible.in some cases attached to portions of the reticulum which have 
contracted far away from the original position of the nuclear wall. In 
the late prophase, when the definitive chromosomes are formed, a 
distinct and perfect nuclear membrane is invariably present, so it 
would appear that in such cases as those just described a new mem- 
brane is afterward formed. | 
Mention must now be made of the chromatic staining material of 
the nucleus during these stages. . The nucleolus is frequently, though 
not always, included within the synaptic knot. There is a tendency 
for other dark-staining bodies to accumulate near the periphery of 
the nucleus (figs. 12, 14); as contraction proceeds these are swept in 
by the reticulum. The exact relation they bear to the threads is not 
known. In some cases they appear, in the later stages of contraction 
at least, to form a part of the threads themselves, in other cases they 
appear to be merely inclusions in its coils. These bodies show no 
constancy in number, size, or shape. As the spirem takes on the ap- 
pearance of the synaptic knot, they are still found in its meshes, and 
portions of the thread itself may also stain darkly, suggesting a 
solution of a part of their substance and its transfer into the thread. 
Even when the greater part of the spirem is completely decolorized 
certain portions of it retain the stain. This appears to be partly 
