Centrifugal Force on Plants. 145 
rather delicate plants of this kind can stand and finally recover. This they 
did, when planted, in about two weeks so that at the expiration of that time 
no difference was visible between the experimental and the control plants 
as seen above ground in the growth of the stem. In many cases the growth 
of lateral roots makes a very prolonged experiment impracticable. In each 
sase when the roots were marked off in the usual way to show the growing 
region whose growth was lessened as shown by comparison the growth 
was not completely stopped in any zone. Other than that the growth was 
decreased in the growing zones the regions and relation of growth to the 
controls remained the same. Many more experiments have been made on 
other plants which confirm these points. The centrifugal force therefore 
used by Schwartz and Elfing and others did not cause a noticeable differ- 
ence simply because it was not of sufficient intensity. In all the experiments 
which I performed the contents of all the cells was thrown to the centrifugal 
end of the cell, It returned to its normal postion in the various cells 
whether they were large or small after two to three days. Even after 
the contents had returned to its normal position, as indicated above, a much 
longer time was still necessary to allow the complete shock of the centrif- 
ugal force to disappear. This varied according to the plant and the intens- 
ity of the centrifugal force, 
