1914] on Plant-Autographs and their Revelations mi 



temperature, the time required for transmission throuf^h the same 

 distance is continuously reduced. In the present case the velocity is 

 seen to be more than doubled by a rise of temperature through 

 9 desfrees. 



Fig. 14. — Effect of Rising Temperature in Enhancing 

 Velocity of Transmission. The three records from below 

 upwards are for temperatures 22° C, 28'^C. and31°C. respectively. 



The converse experiment is to subject a portion of conductinir 

 petiole to the action of cold. This retards the speed of conduction. 

 Excessive cold temporarily abolishes the conducting power. 



Induced Paralysis axd its Cure by Electric Treatment. 



As an after-effect of the application of intense cold, the conduct- 

 ing power remains paralysed for a considerable length of time. It is 

 a very interesting and suggestive fact that I have been able to 

 restore the conducting power quickly by subjecting the paralysed 

 portion of the plant to a measured and moderate dose of electric 

 shocki The application of too strong an intensity is, however, very 

 detrimental. 



Block of Conduction by the Action of Poison. 



I have also succeeded in arresting conduction of excitation in 

 plants by local appHcation of poisonous drugs. The defect of Pf effer \s 

 experiment lay in his attempt to arrest the impulse by the application 

 of a volatile anaesthetic like chloroform, on a surface of a thick stem. 

 The chloroform escapes in the form of vapour ; the access of the 

 solution under these conditions to the interior of the tissue by ab- 

 sorption can only be slight, and therefore ineffective in arresting the 

 excitatory impulse. It occurred to me that the physiological block 

 induced by a druo- could be rendered more effective in two different 



