66 RESPONSE IN THE LIVING AND NON-LIVING 



for five minutes in water at 55 C. This, as will be seen 

 from the record taken afterwards, effectively killed the 



plant (fig: 38, w). 



Increased sensitiveness as after-effect of temperature 

 variation. A very curious effect of temperature varia- 

 tion is the marked increase of sensitiveness which often 



19* C 



30 C 



25C 



50 C 



Temperature, 

 faUiruj 



50 C 



70 C 



Temperature rising >- 



FIG. 39. EFFECT OF RISING AND FALLING TEMPERATURE ON THE RESPONSE 

 OF SCOTCH KALE 



appears as its after-effect. I noticed this first in a series 

 of observations where records were taken during the 

 rise of temperature and continued while the tempera- 

 ture was falling (fig. 39). The temperature was 

 adjusted by electric heating. It was found that the 

 responses were markedly enhanced during cooling, as 



