THe EFFrect OF CENTRIFUGAL FORCE ON OSCILLATORIA. 
Frank M. ANDREWS. 
Filaments of Oscillatoria were centrifuged in order to ascertain if it 
were possible to displace the contents to any extent. First I used a force 
of 1,738 gravities. This force did not change the position of the contents 
in any respect, although the plants were centrifuged two days and four hours. 
The growth of the filaments also had not ceased and the movements so 
characteristic of the plant had not been interrupted. The filaments were 
not harmed in any way by such centrifugal action as a comparison with 
control specimens showed. 
In a second experiment the filaments were subjected to 4,400 gravities 
for two hours and later to 5,843 gravities for three hours, but no displace- 
ment of the contents was caused. 
In a third experiment 13,467 gravities were used transversely on the 
filaments for one hour with no change in the position of the contents; neither 
cessation of the growth nor of the usual movements. When Oscillatoria was 
centrifuged between the slide and cover-glass the filaments were usually 
broken, yet very short pieces consisting of a few cells often withstood a force 
of 1,738 gravities. For the use of very high centrifugal forces, as indicated 
above, it was necessary to place the filaments directly on the bottom of 
the glass cylinders and centrifuge them transversely as stated above. The 
filaments were then broken apart into their disk-like cells and observed from 
the end, but no displacement of the contents could be seen. The amount 
of resistance of such delicately constructed plants is rather surprising. It 
is also interesting to note that in all the experiments with centrifugal force 
on Oscillatoria, the characteristic movements were not stopped or apparently 
retarded by a force varying from 1,738 gravities to as much as 13,467 gravities. 
This was shown by specimens of Oscillatoria which were placed directly on 
the bottom of the glass cylinders on the outside of which was fastened a 
graduated scale. The machine was stopped in a few seconds and by ob- 
servation it could be seen that the specimens that had been centrifuged for one 
hour or more and with any amount of centrifugal force had moved or radiated 
as far as the control specimens had in the same time. These movements 
