294. PROF. J. C. BOSE ON ELECTRIC RESPONSE IN 
‘to fix an absolutely neutral point, but a point may be found 
which approaches this very nearly (fig. 17 a), and on stimulating 
near this point a very interesting diphasic variation was observed, 
which was due to a slight difference in the rates of propagation of 
the disturbance in the two directions. From the record (fig. 17 ¢) 
it will be seen that the disturbance arrived earlier at A than 
at B. This produced an “ up” response. But shortly after, the 
wave reached B. The effect of this was to produce a current in 
the opposite direction. This apparently hastened the recovery 
Fig. 17 ¢. 
Fig. 17 a. 
Diphasic variation. 
of A (from the normal 60 seconds to 12 seconds), and then the 
second phase of response “down” due to excitation of B was 
fully displayed (fig. 17 ¢). 
Radial Electromotive Force. 
We have seen that a current of response in the plant flows 
from the relatively more to the relatively less excited. A 
theoretically important experiment is the following :—A thick 
plant-stalk is taken, and a hole bored so as to make one contact 
with the interior of the tissue, the other being on the surface. 
After a while the current of injury was found to disappear. 
. On exciting the tissue by taps or torsional vibration a respon- 
sive current was observed which flowed inwards, from the more 
disturbed outer surface to the shielded core inside (fig. 18). 
