EFFECT OF TEMPERATURE ON ELECTRICAL RESPONSE 183 



temperature of 2 C. On now again trying to obtain 

 response, it was found that it had practically disappeared. 

 The same specimen was next warmed to 20 C., and this 

 induced a revival of response (fig. 122). 



I was next desirous of studying the after-effect of lowered 

 temperatures on different plants. For this purpose I chose 

 three specimens (i) the 

 petiole of Eucharis Lily, 

 (2) the stem of Ivy, 

 and (3) Holly. I took 

 their normal responses 

 at 17 C., and after- 

 wards placed them in 

 an ice-chamber at a 

 temperature of o C. 

 for 24 hours. The 

 specimens were then 

 taken out, and their 

 responses under stimu- 

 lation once more re- 

 corded (fig. 123). From 

 these it will be seen 

 that while the respon- 

 siveness of the delicate 

 Eucharis Lily was com- 

 pletely abolished, that 

 of the hardier plants, 

 Holly and Ivy, exhibited 

 complete revival. 



One interesting fact 

 which I have noticed 

 is that when a plant approaches its death-point, by reason 

 of excessively high or low temperature, not only is its re- 

 sponse, of galvanometric negativity, diminished to zero, but 

 it is even occasionally reversed to positive. This effect 

 is due to the unmasking of the positive, by the abolition 

 of the true excitatory component. 



(b) 



FIG. 122. Diminution of Response in 

 Eucharis by Lowering of Temperature 

 (a) Normal response at 17 C. 

 (6) The response almost disappears when plant 



is subjected to 2 C. for fifteen minutes. 

 (c) Revival of response on warming to 20 C. 



