33i 
Centrifugal Force upon the Cell. 
When the opening is equal to about one-half the transverse 
diameter of the cell or a little less, the progress of the retreat- 
ing contents is greatly retarded, but finally a portion succeeds 
in passing through and distributing itself in that portion of 
the cell. 
Transverse walls which were being formed at the time of 
centrifugal action were never completed. Several instances 
were closely observed from day to day for three consecutive 
weeks, during which time the contents had become uniformly 
redistributed ; but the cellulose-ring remained unchanged, 
except undergoing secondary thickening by the apposition of 
new layers in common with the entire wall of the cell. 
This fact seems to indicate clearly that, when the relation 
existing between the transverse wall in process of formation 
and the nuclei and movable cytoplasm connected therewith 
is once destroyed, it is not restored again so as to complete 
the cell-wall. It was observed also that later some of these 
♦ cells in question divided, and the division-wall was laid down 
near the old cellulose-ring. We shall return to this phase of 
the subject in a subsequent paragraph. 
As already stated, a violent displacement of all movable 
contents in cells of Cladophora does not interfere materially 
with cell-growth or division, for a day or two after centrifugal 
action it was not at all uncommon to find cells dividing 
whose displaced contents had only fairly begun to redistribute 
themselves (Fig. 3). This fact may throw some light upon the 
relation of the amount of cytoplasm to cell-division. From 
Fig. 3 it will be seen that the resulting daughter-cells are of 
unequal size. The smaller presents a striking contrast in size 
and colour to the larger, which contains only a relatively small 
number of chloroplasts. Very often three or more such cells 
were to be seen in a piece of filament one and a half centi- 
metres long. The entire process of division was followed in 
several cases, so that there can be no doubt as to the accuracy 
of the statement. So far as determined the number of nuclei 
was less in the longer cell (Fig. 3, l?), but whether the quantity 
of cytoplasm is proportional could not be ascertained. 
