PLANT RESPONSE 



I'AGE 



contractile wave by means of electrotactile method — Determination of 

 velocity of transmission of excitation in ordinary plants by electromotive 

 method — Excitatory versus hydro-mechanical movement of water . -254 



CHAPTER XXII 



THE LATENT PERIOD AND REFRACTORY PERIOD 



The determination of the latent period in Mimosa — Experimental arrange- 

 ments for obtaining automatic record — Prolongation of latent period by 

 cold— Spark-record for determination of latent period— Prolongation of 

 latent period by fatigue — Sluggishness of the response of Pliilanthus 

 urinaria, also long latent period and very protracted period of recovery 

 ■ — Latent period reduced under strong stimulation — Response in 

 Biophytiim on the ' all or none ' principle — Definite value of effective 

 stimulus — Phenomenon of refractory period in Biophytiim — Parallelism 

 of responses in Biophytiim and in cardiac muscle — Additive effects — 

 Inappropriateness of term ' refractory period ' — Energy in excess of 

 effective stimulus held latent for subsequent manifestation . . . 264 



PART IV.— MULTIPLE AND AUTONOMOUS 

 RESPONSE 



CHAPTER XXIII 



ON MULTIPLE RESPONSE 



Multiple electromotive responses due to a single strong stimulus — Multiple 

 electrotactile responses — Multiple mechanical responses in Biophytiim — 

 Cyclic variations in multiple responses — Multiple retinal excitations — 

 Intermittent pulse in man and plant — Semi-automatism — Continuity of 

 multiple and automatic response — Conversion of Biophytiim into auto- 

 matically responding plant ; conversion of Desviodiiim into ordinarily 

 responding plant — Similar polar effects of current in Biophytiim and in 

 Desmodiiim leaflet at standstill — Moderate stimulus in Biophytiim and 

 in Desmodium at standstill produces single response ; and strong stimulus, 

 multiple response 279 



CHAPTER XXIV 



AN INQUIRY INTO THE CAUSES OF AUTONOMOUS MOVEMENTS 



Production of pulsatory movements as after-effect of energy absorbed — 

 Physical analogue -Localisation of seat of automatic excitation in Des- 

 modium — Demonstration of multiple response to a constant stimulus : 

 (I) Chemical— (2) Electrical— (3) Stimulus of light— Multiple reiix»nse 



