470 



LIFE MOVEMENTS IN PLANTS 



Tl#e root-tip thus exhibits the characteristic response to direct 

 stimulation. Experiments carried out with 12 differeut 

 specimens gave concordant results. The following table 

 gives the absolute values of electro-motive force induced 

 at the tip under geotropic stimulus. 



TABLE XXXVII. — GEO-ELKCTUIC RESPONSE OF THE KOOT TIP (Vicia Faba). 



ELECTRIC RESPONSE IN THE GROWING REGION. 



Experiment 183. — I next undertook an investigation on 

 the electric variation induced in the growing region under 

 the stimulus of gravity. The experimental difficulties are 

 here greatly reduced, since the available area of contact 

 for galvanometric 9onnection is not so restricted as in the 

 case of the root-tip. The specimen is securely mounted so 

 that the root is vertical. It is next rotated in the vertical 

 plane through -f-90°, so that the point A in the growing 

 region occupied the upper position. The electric response 

 in the growing region took place in a short time and was 

 very distinct. The induced electric change at A was now 

 galvanometric positivUy indicative of increase of turgor 

 and expansion. 



