to RESPONSE IN THE LIVING AND NON-LIVING 
on the surface. After a while the current of injury was 
found to disappear. On exciting the stem by taps or 
torsional vibration, a responsive current was observed 
which flowed inwards from 
the more disturbed outer 
surface to the shielded core 
inside (fig. 29). Henee it is 
seen that when a wave of 
disturbance is propagated 

Fic. 29.—Rapi1at E.M. Variation along the plant, there is a 
concomitant wave of radial 
H.M. variation. The swaying of a tree by the wind 
would thus appear to give rise to a radial E.M,F. 
