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- 
