336 RESEARCHES ON IRRITABILITY OF PLANTS 



Application of undiluted gas, however, induces an arrest. 

 If fresh air be now substituted, there is produced a slow 

 revival of pulsation (fig. i8o). 



In another experiment I obtained a record of the effect 

 of internal application of water charged with carbonic acid. 

 The pulsating activity was found slowed down, the ampli- 

 tude of the pulsation also undergoing a diminution. The 

 depressing effect is, however, seen to pass away gradually 

 (fig. i8i). 



Effect of Ether 



This agent was applied in the form of vapour, which was 

 slowly blown into the plant-chamber. If the vapour be 



Fig. 182. — Effect of vapour of ether; depression and subse- 

 quent arrest. Pulsations revived on blowing off the vapour. 



much diluted with air, then the first effect of ether is to 

 induce a transient exaltation, followed by depression and 

 arrest of pulsation. If the leaflet be subjected to strong 

 vapour, or if the application be prolonged, then the arrest 

 of pulsation proves to be permanent. But if diluted vapour 

 is employed and fresh air substituted immediately after 

 the arrest, then there is a slow revival of pulsation. 

 This can be seen in fig. 182, where after the application of 

 ether an arrest took place after three rapidly diminishing 

 pulsations. On blowing off the ether vapour, the pulsation 

 is seen to revive slowly after a period of 20 minutes. 



Effect of Chloroform 



The effect of this reagent on the pulsation of Desmodium 

 is similar to that of ether. It is, however, far more toxic in 

 its reaction, a slight excess in the application being attended 



