3 o RESPONSE IN THE LIVING AND NON-LIVING 



in any way explain the reversible nature of these 

 responses, when A and B are stimulated alternately. 

 These responses are obtained in the plants even when 

 completely immersed in water, as in the experimental 

 arrangement (fig. 15). It will be seen that in this 

 case, where there could be no possibility of shifting of 

 contact, or variation of surface, there is still the usual 

 current of response. 



I shall describe here a few crucial experiments only, 

 in proof of the physiological character of electric 

 response. The test applied by physiologists, in order 

 to discriminate as to the physiological nature of re- 

 sponse, consists in finding out whether the response is 

 diminished or abolished by the action of anaesthetics, 

 poisons, and excessively high temperature, which are 

 known to depress or destroy vitality. 



"I shall therefore apply these same tests to plant 

 responses. 



Effect of anaesthetics and poisons. Ordinary anaes- 

 thetics, like chloroform, and poisons, like mercuric 

 chloride, are known to produce a profound depression 

 or abolish all signs of response in the living tissue. 

 For the purpose of experiment, I took two groups of 

 stalks, with leaves attached, exactly similar to each 

 other in every respect. In order that the leaf-stalks 

 might absorb chloroform I dipped their cut ends in 

 chloroform-water, a certain amount of which they 

 absorbed, the process being helped by the transpira- 

 tion from the leaves. The second group of stalks was 

 placed simply in water, in order to serve for control 

 experiment. The narcotic action of chloroform, finally 



