48 BOTANICAL GAZETTE [JANUARY 
examined and not a selected few, there seems to be more evidence of 
the first being the true account of events. 
It was thought at first that this difference in number of chromosomes 
might be due to difference of species, as none of the Zygnema exam- 
ined had zygospores, and hence it is possible that two or more species 
might have been growing together. The discovery of cells like those 
_ in figs. 6, 12, 13, 15, 23, 22, in the same filament is indisputable evi- 
dence that in the same individuals the number of chromosomes de- 
creases from thirty or more down to six or eight, and then increases to 
thirty or more. This change in number occurs in a few moments, as 
determined in living cells by the changes in the position of the nucleus. 
All the filaments were examined in surface view, so it cannot be 
maintained that the number of chromosomes had been increased by 
sectioning. 
As the rings of chromosomes approach the chromatophores, the 
cytoplasm is condensed on the side nearest the chromatophore. 
The explanation of this might be that a large part of the cytoplasm 
which is not diverted to the region of the formation of the cell plate 
was streaming in toward the center, as in jigs. 14-18, while in figs. 
20-30 it was streaming out towards the chromatophores; that the 
chromosomes are forced together by the inflowing streams and in 
the vortex of opposing currents become dissociated. The word 
“dissociated” is used in preference to the word “splitting,” as there 
appears to be no evidence of splitting and hence of equal distribution 
of homogeneous bodies. The chromosomes being heavier than the 
cytoplasm, the condensation appears on the side nearest the chro- 
matophore (figs. 28, 29). | 
It is to be regretted that in the living cells chromosomes could 
not be distinguished from actively vibrating granules in the cytoplasm. 
Nothing could be discovered which in any way resembled spindle 
fibers, although streams of granules and the alternating space of 
nuclear activity was easily traced. 
The number of chromosomes finally arriving at the chromatophore _ 
may be fifteen to twenty in each ring, as in fig. 30. The cytoplasm, 
being somewhat arrested in its flow by the chromatophore, causes a 
change in the position of the chromosomes. The majority, as they 
undergo still further dissociation, are drawn to the center, incom- 
