330 
Mot tier . — The Effect of 
colourless cytoplasm, retreat partly along the ectoplasm and 
partly upon the lamellae. 
It may be mentioned, however, that as soon as observation 
is possible after centrifugal action an active streaming of 
a thin layer of cytoplasm is to be seen upon the lamellae and 
along the hautschicht . This is true in all cells of the various 
plants observed at the time in question ; the movement is, of 
course, toward the end of the cell from which the contents 
were made to fall. 
Although, as previously mentioned, the retreating contents 
proceed in a tolerably uniform layer, yet this layer does not 
contain as many chloroplasts and nuclei as were originally 
distributed over the same area of the cell. Many of these 
bodies travel more slowly than others ; for when the retreating 
layer or mass reaches the opposite end of the cell this end 
presents a light, pale-green colour which passes over gradually 
into the deep green of the other end into which the contents 
were thrown. 
A noteworthy phenomenon presents itself in cells that were 
undergoing division at the time of centrifugal action. If the 
ring-shaped membrane were narrow, the contents of one 
daughter-cell would be forced through into the opposite end 
of the other, just as if no cellulose- ring were present (Fig. 2). 
If, however, the forming transverse wall had proceeded to 
such an extent that the circular opening remaining was only 
one-third or one-half the diameter of the cell, a few chloro- 
plasts were generally lodged against the new wall. This was 
often the case in Spirogyra , to be mentioned later, where 
often an end or fold of some chlorophyll-band caught against 
the ring-shaped membrane. When, on the contrary, the 
opening remaining in the membrane was smaller, in large cells 
less than one-half the diameter, the chlorophyll-grains were 
not forced through. 
During redistribution of the displaced contents in such cells, 
as just mentioned, the retreating mass creeps back through 
the opening in the incomplete transverse membrane, and 
becomes equally distributed as under ordinary circumstances. 
