296 PROF. J. C. BOSE ON ELECTRIC RESPONSE IN 
Hence it is seen that when a wave of disturbance is propa- 
gated along the plant, there is a concomittant wave of radial 
Fig. 18. 
Radial E.M. variation. 
E.M. variation. Swaying of a tree by the wind would thus 
appear to give rise to a radial E.M.F. 
Abnormal Response. 
The current of response in fresh nerves is from the more 
excitable to the less excitable, and the normal response is called 
“negative.” The normal response in plants is similar in 
direction to the nerve-response. If we wish to keep in touch 
with the animal phraseology, we might also designate the plant- 
response as negative. , 
But stale nerve, owing to some peculiar molecular modifica- 
tion, gives rise, as Dr. Waller found, to the abnormal positive. 
This abnormal response is reversed to the normal negative after 
strong and long-continued stimulation. Curiously enough, I 
have on many occasions found exactly parallel instances of 
reversed response in stale plants, and, what is more interesting, 
the abnormal positive passed into normal negative when subjected 
to strong stimulation. I was able in some cases to trace the 
process of reversal, by continuously increasing the intensity ot 
stimulus. It was found that as the stimulus was increased, at a 
certain point, the positive underwent a reversal into the normal 
negative. This is seen in fig. 19, in which the record should be 
read from right to left. The responses are at first abnormal 
positive (up); on increasing the stimulus, at a certain point there 
was produced (see the extreme left of the figure) a normal 
negative (down) response. 
The plant thus gives reversed response under the abnormal 
condition of staleness. I have sometimes found similar reve 
of response when the plant is subjected to the abnormal 
