333 
Centrifugal Force upon the Cell . 
was removed from the centrifuge. It had been subjected 
for three-fourths of an hour to a force of 1820 £*. All the 
movable contents were heaped up in the end of the cell. As 
soon as observation is possible after the cessation of centri- 
fugal action (it required about five minutes to stop the 
machinery and remove the preparations), an active streaming 
movement toward the opposite end of the cell is seen in 
very finely granular cytoplasmic strands extending along the 
hautschicht . These strands generally anastomose. Not in- 
frequently, and in very large cells especially, a cytoplasmic 
band is formed which encircles the cell in an exactly trans- 
verse direction. Movement within such a band follows the 
direction of the same. With the gradual redistribution of 
the cell-contents these bands, when present, progress Uniformly 
in front of the chloroplasts. 
About twenty or twenty-four hours after centrifugal action, 
a thicker layer of fine granular cytoplasm is distributed over 
the entire surface of the hautschicht (Fig. 5) i.e., the primor- 
dial utricle is now thicker. It is also to be seen (Fig. 5) that 
the chlorophyll-bands, together with the nucleus suspended 
by cytoplasmic strands which extend apparently from the 
pyrenoids, have begun to creep back to resume their position 
in the cell. It often happens, however, that the bands do not 
stretch out evenly, contiguous edges often adhering so as to 
give the bands a tangled appearance. This is generally true 
when a larger number of bands with steep turns are present 
in the cell. In such cases a longer time is necessary for an 
even and complete redistribution. Whenever only two or 
three bands are present, distribution is quite uniform and 
regular (Fig. 6). 
In cells such as represented in Figs. 5 and 6, a complete 
redistribution may take place in seven or eight days, perhaps 
sooner, but often fifteen to eighteen, and even more, are neces- 
sary. 
The rapidity with which redistribution takes place, as will 
be seen later, depends to some extent upon the temperature 
and perhaps illumination. In many instances when redis- 
