IO COMPARATIVE ELECTRO-PHYSIOLOGY 



is consequent on the other It would be as incorrect to 

 suppose that the electrical effect depended on the mechanical, 

 as to assume that the mechanical was brought about by the 

 electrical. The two are independent expressions of the same 

 fundamental molecular change, brought about by the shock 

 of stimulus. 



Again, those various responsive phenomena and their modi- 

 fications which are the subject of our inquiry, are such as are 

 induced by different external agencies. Under the influence 

 of certain conditions, the responses of living matter undergo 

 an abolition the change which we associate with death. In 

 inorganic matter also, we find a similar change of responsive- 

 ness into irresponsiveness, to take place. The death-change 

 in the case of living matter is thus not due to a change from 

 the organic to the inorganic condition, but to some molecular 

 transformation. And the nature of this very obscure trans- 

 formation may one day be elucidated by a careful study of 

 the changes which take place in inorganic matter, when it 

 passes from responsivity to irresponsivity. 



The word ' physiological ' is generally used to distinguish 

 phenomena which are believed to be exclusively characteristic 

 of the properties of living matter. Such phenomena, however, 

 are found, as our power of investigation grows, to be increas- 

 ingly capable of analysis into physico-chemical processes. 

 In my own use of the term ' physiological,' therefore, it will 

 be understood as a convenient expression for describing the 

 response-phenomena of plant or animal tissues, but as in no 

 sense opposed to the word ' physical.' 



We shall, in the following chapters, study excitatory 

 effects in living tissues, and their variations under different 

 conditions, using the methods of electrical response. These 

 phenomena will be studied with special detail in the case of 

 vegetable tissues, and it will be found that there is no 

 responsive reaction exhibited by any one amongst the various 

 types of animal tissues, which has not its exact corre- 

 spondence in the vegetable. Those anomalies, further, which 

 have been observed in the response of the animal, will be seen 



