EFFECT OF TEMPERATURE ON ELECTRICAL RESPONSE 183 



(C) 



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- 

 ation once more re- 

 corded (fig. 123). From 

 these it will be seen 

 that while the respon- 

 siveness of the delicate 

 Eucharis Lily was com- 



Dletely abolished, that 



Of the hardier plants, FIG. 122. Diminution of Response in 



r Eucharis by Lowering of Temperature 



Holly and Ivy, exhibited (a) Normal response at i;0 c 



mplete revival. W Tne response almost disappears when plant 



~ . r is subjected to - 2 C. for fifteen minutes. 



Une interesting tact (<) Revival of response on warming to 20 C. 



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- 



I sponse, of galvanometric negativity, diminished to zero, but 



\ it is even occasionally reversed to positive. This effect 



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



of the true excitatory component. 





