339 
Centrifugal Force upon the Cell ' 
is, of course, more pronounced on the side next to the vacuole 
(Fig. 9 , c to g). The cytoplasmic strands running from the 
plasmic mass to the hautschicht change position, while 
additional ones appear. The growth of the cell-plate 
(Mottier ’97) keeps pace with the diametrical increase of the 
system of connecting fibres at the equator, so that when the 
latter reaches the opposite wall a transverse membrane is 
formed and cell-division is complete. The increase in diameter 
of the system of connecting fibres is accompanied by a shorten- 
ing of its length, so that when the cell-plate is formed the 
daughter-nuclei come to lie close to it. In a short time now 
the entire contents of each cell assume their normal orienta- 
tion. The processes embraced by a and /, Fig. 9 , required 
forty minutes ; between /and^, eight minutes. 
A division of the cell often takes place before the nucleus 
regains its more central position, displacement having been 
longitudinal. The result of such a division is shown in 
Fig. 8 , in which the daughter-cells are of unequal size. This 
figure was drawn twenty-four hours after displacement. In 
this case it is not known whether or not the cell was in 
division at the time of centrifugal action ; but other instances 
were observed in which both nucleus and cell divided while 
the former lay in the end of the cell. It is doubtful whether 
nuclear or cell-division can continue during the action of 
centrifugal force as great as that used, for the phenomena 
observed immediately afterwards seemed to indicate clearly 
that the karyokinetic process is inhibited. No special effort 
was made to determine whether the process is accelerated or 
retarded as a result of centrifugal action. The time required 
for the completion of that part of the process illustrated in 
Fig. 9 was nearly the same as for corresponding phases under 
ordinary conditions. The difference, if there be any, is 
certainly small, whether on the side of acceleration or 
retardation. 
These observations seem to indicate further that, where the 
cell-wall is laid down through the direct instrumentality of 
the kinoplasmic connecting fibres, its position in the cell is 
