ADJUSTMENT TO SURROUNDINGS 127 



right angles to their long axis. Such an influence is the 

 centrifugal tendency produced by motion in a circle. If 



FIG. 85. Knight's experiment, substituting centrifugal "force" for 

 gravity. (After Knight.) 



seedlings are fastened to a wheel, with the root and shoot 

 pointing in various directions, and the wheel rapidly ro- 

 tated, the growing root will bend until it points in the di- 



