92 RESEARCHES ON IRRITABILITY OF PLANTS 



noticeable is the alternating character of the response that 

 took place after the application of alcohol. 



Ether 



The vapour of ether induces a depression of excitability 

 as seen in the diminution of amplitude of response. The 

 first effect of dilute ether-vapour is often a short-lived 

 exaltation. The narcotic effect of this agent on Mimosa 

 is feeble compared with that induced by chloroform. The 



Fig. 49. — Effect of ether. 



depressing effect of ether passes off on readmission of 

 fresh air (fig. 49). 



Carbon Disulphide 



The effect of vapour of carbon disulphide is similar to 

 that of ether. It induces a depression during the introduc- 

 tion of vapour into the plant-chamber ; the induced depres- 

 sion, however, passes off on restoration by means of fresh 

 air (fig. 50). 



Coal Gas 



Contrary to my anticipation, coal gas proved to be 

 but moderately depressing in its action. I have kept the 

 plant surrounded by this gas for more than two hours 



