ELECTRIC RESPONSE IN PLANTS 



vibration. It is of course obvious that if the length 

 of the specimen be doubled, the vibration, in order 

 to produce the same effect, must be through twice the 

 angle. I took a leaf-stalk of turnip and fixed it in the 

 torsional vibrator. I then took record of responses to 

 two successive taps, the intensity of one being nearly 

 double that of the other. Having done this, I applied 

 to the same stalk two successive torsional vibrations of 

 45 and 67 respectively. These successive responses 



FIG. 12. KESPONSE IN PLANT TO MECHANICAL TAP OR VIBEATION 



The end B is injured. A tap was given between A and B and this 

 gave the response-curve a. A stronger tap gave the response b. 

 By means of the handle H, a torsional vibration of 45 was now 

 imparted, this gave the response c. Vibration through 67 gave d. 



to taps and torsional vibrations are given in fig. 12, 

 and from them it will be seen that these two modes 

 of stimulation may be used indifferently, with equal 

 effect. The vibrational method has the advantage over 

 tapping, that, while with the latter the stimulus is 

 somewhat localised, with vibration the tissue subjected 

 to stimulus is uniformly stimulated throughout its 

 length. 



Effectiveness of stimulus dependent on rapidity also. 

 In order that successive stimuli may be equally effective 



