328 
Mottier . — The Effect of 
In order to observe the behaviour of the cells from time to 
time after the application of centrifugal force, the preparations 
were kept in a moist chamber ; and, when the plants operated 
with were Algae, one end of the slide was allowed to dip into 
the water. The water was renewed every day or two to 
prevent the accumulation of bacteria and other foreign 
organisms. From time to time a small quantity of gypsum 
was thrown into the water of the moist chamber or small 
aquarium to prevent a too rapid dissolution of the gypsum 
casts, and as it was found that the Algae thrived better in the 
dilute gypsum-solution than in the tap-water alone. 
For the most part the centrifugal force was allowed to act 
parallel to the longitudinal axis of the cell ; but also fre- 
quently, for the sake of comparison, in an oblique and 
transverse direction. 
We shall direct our attention first to the effect of centri- 
fugal force acting longitudinally. 
Specimens of Cladophora were subjected for about one 
hour and a half to a centrifugal force varying from 1700 to 
1800 g. 
The time necessary to bring about the desired displacement 
when the force remains constant varied with the size of the 
cell and the nature of the contents. 
In cells of Cladophora , with the proportional dimensions of 
Figs. 1 and 2, immediate observation after centrifugal action 
showed that almost the entire contents were crowded into 
a dense mass at the end of the cell. Apart from an occa- 
sional chloroplast and sometimes a nucleus, nothing of the 
living substance or its inclusions remains undisturbed except 
the ectoplasm or hautschicht and the plasmic lamellae which 
penetrate the cavity of the cell and divide it into a number of 
irregular polygonal chambers varying much in size (Figs* 
1 and 2). 
Seen with the low power of the microscope, each cell 
appears perfectly colourless with a dense dark-green mass 
at one end. In all probability the lamellae always remain 
stationary or nearly so, and the chloroplasts and nuclei fall 
