EFFECTS OF DIFFERENT GASES 97 



of the motile excitability of pulvinus. Excitability is 

 restored under application of glycerin. 



Ozone enhances the excitability of Mimosa. 



Carbonic-acid gas and vapour of alcohol induce a 

 moderate depression of excitabihty, which is fully restored 

 on admission of fresh air. 



Depression of excitability is also induced under the 

 action of coal gas, and vapour of carbon disulphide. 



The vapour of ether exerts a moderate narcotic action. 

 The effect of vapour of chloroform is very pronounced, 

 loss of excitability under its action being prolonged. 



x\mmonia induces a marked abolition of excitability. 



Sulphuretted hydrogen, nitrogen dioxide, and sulphur 

 dioxide aboHsh the excitability and bring about the death 

 of the plant. 



