viii COMPARATIVE ELECTRO-PHYSIOLOGY 



were thus in reality different reactions to the stimulating action 

 of energy supplied by the environment. 



With regard to these points, my results have been in direct 

 opposition to current views, according to which the effect 

 induced by stimulus is always disproportionately greater 

 than the stimulus. From the plausible analogy of the 

 firing-off of a gun by the pulling of a trigger, or the action 

 of a combustion-engine, it has been customary to suppose 

 that all response to stimulus must be of the nature of an 

 explosive chemical change, accompanied by an inevitable 

 run-down of energy. This supposition, however, overlooks 

 the obvious fact that the plant is not consumed by the 

 incessant and multifarious stimuli of its environment. 

 Rather, as we all know, it is the energy of the environ- 

 ment which is the agent that fashions the microscopic 

 embryo into the gigantic banyan-tree. And it is clear 

 that, for this to be possible, the energy contributed by the 

 blow of external stimulus must have been largely conserved. 



In the course of the present work, I have not only been 

 able to corroborate, by means of electrical response, the 

 various results which I had already established, with regard 

 to the plant, by mechanical response, but I have also ex- 

 tended the electrical method in various directions, so as to 

 include many more recondite problems in connection with 

 the irritability of living tissues. It was my original inten- 

 tion to confine this investigation to the Electro-physiology 

 of Plants. But, finding that in the results so obtained I pos- 

 sessed a key to that of the animal also, I proceeded to apply 

 the same methods of inquiry, and to use the same experi- 

 mental devices, in the one case as in the other. I have thus 

 been able to trace out the gradual differentiation of various 



