284 PROF. J. C. BOSE ON ELECTRIC RESPONSE IN 
The torsional method, however, has the advantage over tapping 
that, while with the latter the stimulus is somewhat localized, with 
torsional vibration the tissue subjected to stimulus is uniformly 
stimulated throughout its length. Successive taps applied to 
the same point are again productive of injury to the plant. 
Effectiveness of Stimulus dependent on Rapidity also. 
In order that successive stimuli may be equally effective, 
another point has to be borne in mind. In all cases of 
stimulation of living tissue it is found that the effectiveness 
of a stimulus to arouse response depends on the rapidity of 
the onset of the disturbance. It is thus found that the stimulus 
of the “ break” induction-shock on a muscle, for example, is 
more effective, by reason of its greater rapidity, than the 
“make ” shock. So also with the torsional vibration of plants, 
I find response depending on the quickness with which the 
vibration is effected. 
Thus if we wish to maintain stimulus constant, we must meet 
two conditions :—(1) The amplitude of vibration must be kept 
the same: this is done by means of the graduated circle. 
(2) The vibration period must be kept the same: with a little 
practice this requirement is easily fulfilled. 
The uniformity of stimulation which is thus attained solves 
the great difficulty of obtaining reliable quantitative values, by 
whose means alone can rigorous demonstrations of the phenomena 
we are studying become possible. 
Block Method. 
I shall now proceed to describe another and independent 
method devised by me for obtaining plant-response. It has the 
advantage of offering us a complementary means of verifying the 
results found by the method of negative variation. As it is also,. 
in itself, for reasons which will be shown later, a far more perfect 
mode of inquiry, it also enables us to investigate problems 
which it would otherwise have been difficult to attempt. 
We have seen that when the specimen of plant is excited 
throughout its whole length, the effect of A on the galvano- 
meter is balanced by that of B. But if we produce a block, 
by clamping at C, between A and B, so that the disturbance 
made at A by tapping or torsion is prevented from reaching B, 
we shall then have A thrown into a relatively greater excitatory 
