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The Effect 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 



