PREFACE 



The investigations described in the present volume have 

 been an outcome of my work on the Similarity of Responsive 

 Phenomena in Inorganic and Living Matter, first com- 

 municated as a Memoir to the Science Congress at Paris, in 

 August 1900,^ and subsequently expanded into greater detail 

 in my book on ' Response in the Living and Non-Living.' 

 The electrical responses described in the Memoir referred to, 

 had been obtained by the method of conductivity variation. 

 The same problem was next attacked by a different mode of 

 investigation, response being now obtained by electromotive 

 variation.- Believing in the continuity of responsive pheno- 

 mena in the inorganic and organic, I undertook on that 

 occasion to demonstrate by the same method the electrical 

 response of ordinary plants, and to show that every plant, 

 and every organ of every plant, was excitable. It was then 

 generally believed that so-called 'sensitive' plants alone ex- 

 hibited excitation by electrical response, and the proposition 

 that ordinary plants also showed excitatory electrical response 

 to mechanical stimulation, and that such response was appro- 

 priately modified under physiological changes, was much 

 controverted. I have to thank Professor Sidney H. Vines, 



' ' De la Gencralite des Phenomenes Moleculaires produils par PElectricite 

 sur la Matiere Inorganique et sur la Matiere Vivante. ' (Travaux dtc Congr^s 

 International de Physique. Paris, 1900.) 



- Paper read before Royal Society, June 6, 1901. Also P'riday Evening 

 Discourse, Royal Institution, May 10, 1901. 



