1908] GATES—REDUCTION IN OENOTHERA 15 
nothing in the manner of segmentation of the spirem to indicate this. 
However, it is clear enough that one chromosome frequently swings 
around, as already mentioned, and pairs with its neighbor on the 
spirem. We do not really have, then, a transverse division of chromo- 
some bivalents, but a separation of whole (somatic) chromosomes. 
Nothing has been found in the earlier stages which would correspond 
to the gamosomes and zygosomes of STRASBURGER, and even should a 
pairing of parallel threads during synapsis occur (a possibility which 
will be discussed later), the final pairing is between chromosome 
bodies which were lying end to end on a single spirem thread. 
The linin connections during diakinesis appear to be merely the 
more finely drawn out portion of the spirem between the chromosomes. 
As condensation and contraction of the chromosomes progress, 
these linin connections become longer and more delicate (jigs. 31, 33)- 
The chromosomes become more dense and compact, being at first 
oblong-cylindrical (figs. 24, 26) and then more nearly globular or 
pear-shaped (fig. 3z). Certain chromosomes sometimes undergo this 
contraction more quickly than others, as in fig. 29, and the different 
Stages of this condensation may occasionally all be found in the same 
nucleus. In other cases the globular appearance is due to the 
position in which certain chromosomes happen to be lying (fig. 34). 
HETEROTYPIC MITOSIS © 
During the prophase stages last outlined the cytoplasm usually pos- 
Sesses a more or less obscurely radiate appearance. A  felt-work 
of fibrillae finally appears around the nuclear membrane. Later 
these fibrillae come to run tangentially to the latter, terminating in the 
cytoplasm, and by their aggregation in certain regions the multipolar 
spind'e is formed. From this stage the fibers are rearranged to form 
the bipolar spindle, passing through conditions in which the spindle 
‘ppears quadripolar or tripolar in section. In the meantime the 
nuclear membrane has dissolved and the chromosomes are found 
at first in a Cavity surrounded by fibers which preserve the outline of 
the nuclear wall. Later they come in and become attached to the 
chromosomes. Usually the large nucleolus has vanished before this 
time, but occasionally it may still be seen (fig. 35). In fig. 37 the 
small nucleolus is shown, which can very frequently be seen at this 
