RESPONSE TO WIRELESS STIMULATION 179 



subsides exactly at the same rate as its growth-elongation, so 

 that the tip of the plant remains at the same point. This perfect 

 balance is attained by a variable regulator. The compound 

 magnifying lever attached to the plant records the movement of 

 growth. Under exact balance the record is horizontal. Any 

 induced acceleration of growth upsets the balance and, with the 

 particular arrangement of the apparatus, causes a resulting 



FIG. 21. Record of responses of plant to wireless stimulation, (a) Re- 

 sponse to feeble stimulus by acceleration of growth ; (6) response to 

 strong stimulus by retardation of growth ; (c) response to medium 

 stimulation retardation followed by recovery. Down-curve repre- 

 sents acceleration, and up-curve retardation of growth (seedling of 

 wheat). 



down record ; induced retardation, on the other hand, brings 

 about an upset in the opposite direction and an up curve. 

 The results given above (Fig. 21) show that growing plants 

 not only perceive, but also respond to the stimulus of electric 

 waves. These effects were found in all growing plants. The 

 records were obtained with the seedling of wheat. 



Effect of Feeble Stimulus. I first studied the effect of feeble 

 stimulus. This was secured by decreasing the energy of 

 sparks of the radiator. The response was an acceleration of 

 rate of growth as seen in Fig. 21 (a). This is analogous 



