1900] THE CELL PLATE IN HIGHER PLANTS 167 
fact. The method of cell division by constriction of the plasma 
membrane, which occurs in many filamentous alge, may be anal- 
ogous to the growth of the plasma membrane as the cell increases 
in size, with the difference that in the former case the growth of 
the plasma membrane is localized and proceeds without the 
accompanying growth of the cell contents. 
2. I have already indicated what seems to me to be the rela- 
tion of the nucleus to the kinoplasm in the process of cell divi- 
sion. It is the center of the metabolic processes concerned in 
the production of the kinoplasm. Whether there is a transfor- 
mation of some previously existing substance of the cell into the 
filar form of kinoplasm I have not been able to determine. 
From the two facts that no such transformation is visible and 
that a great many of the fibers are used up in the formation of 
a membrane, I think it probable that they are formed anew in 
each cell. That the chromatin is the real center for their for- 
mation is shown by the formation of new radiating fibers around 
the daughter nuclei in the onion during the diaster stage, and 
by the formation of a spindle around a single chromosome 
in the manner described by Juel for Hemerocallis, The history 
of the kinoplasm in a single cell of the higher plants would 
‘sem to be as follows. It is formed as fibers around the 
rete as acenter. In this form the kinoplasm takes part 
bi Ris Process of nuclear division, and later divides the cell 
ee or of the fibers being transformed into a membrane 
dinates a in splitting the plasma membranes of the 
s. 
a ag a cell division does not follow immediately 
pales cat lvision the filarplasm may be absorbed into the 
plasm of the cell, either to reappear or to be formed 
an 
i ce needed for cell division. The ultimate form of the 
bec Piasm of any one cell seems to be reached when it has 
Ome 
ONS Saat membrane. It is then concerned with the 
rom the fila Arenas 2 cell. The transformation of kinoplasm 
hypothesis as into the membrane form seems to show that the 
a permanent substance, which may be described 
