50 4 



65 



PLANT RESPONSE 65 



least, recovery was quicker. At 20 C., for example, 

 the response was 21 dns., and the recovery was not com- 

 plete in the course of a minute. At 30 C., however, 

 the response had been reduced to 7'5 divisions, but 

 there was almost complete recovery in twelve seconds. 

 As the temperature was gradually increased, a con- 

 tinuous decrease of response occurred. This diminution 

 of response with increased temperature appears to be 

 universal, but the quickening of recovery may be true 

 of individual cases only. 



TABLE SHOWING DIMINUTION OP RESPONSE WITH INCREASING 

 TEMPERATURE 



(01 Volt = 35 divisions) 



Temperature Response Temperature Response 



20 21 



30 7-5 



40 5-5 



In radishes response disappeared completely at 

 55 C , but with celery, heated in the manner described, 

 I could not obtain its entire abolition at 60 C. or even 

 higher. A noticeable circumstance, however, was the 

 prolongation of the period of recovery at these high 

 temperatures. I soon understood the reason of this 

 apparent anomaly. The method adopted in the present 

 case was that of dry heating, whereas the previous ex- 

 periments had been carried on by the use of hot water. 

 It is well known that one can stand a temperature of 

 100 C. without ill effects in the hot-air chamber of a 

 Turkish bath, while immersion in water at 100 C. would 

 be fatal. 



In order to find out whether subjection to hot water 

 would kill the celery-stalk, I took it out and placed it 



F 



