190 COMPARATIVE ELECTRO-PHYSIOLOGY 



When the temperature is raised above a certain critical 

 point, the plant is killed, and its electrical response dis- 

 appears at the same time. This is demonstrated visually in 

 the accompanying photographic record (fig. 127). In this 

 case, normal responses were first obtained at the usual tem- 

 perature of the room. Steam was next introduced into the 



Before j After 



FIG. 127. Photographic record showing effect of Steam in abolishing 

 Response 



The two records to the left exhibit normal response at 17 C. Sudden 

 warming by steam induced at first an increase of response, but five 

 minutes' exposure to steam killed the plant (carrot) and abolished the 

 response. 



Vibrational stimulus of 30 applied at intervals of one minute ; vertical 

 line = ! volt. 



plant-chamber, and kept streaming in during the course ot 

 the experiment, electrical responses being recorded mean- 

 while at intervals of one minute. It will be seen that at first 

 a transitory augmentation ol excitability was induced. But 

 this quickly disappeared, and in five minutes the plant was 

 effectively killed, as is shown in the waning and final aboli- 

 tion of response. This experiment affords us a qualitative 

 demonstration of the abolition of response at death under 



