xvi PLANT RESPONSE 



CHAPTER XV 



EFFECT OF VARIOUS AGENCIES ON DEATH-RESPONSE : 

 THERMOGRAPHS OF REGIONAL DEATH 



PAGE 



Lowering of death-point by fatigue— Modification of characteristic thermo- 

 mechanical curve by the action of chemical agents --Comparison- 

 Morograph — Duplication of rigor-point — Death-response a physiological 

 response and not due to coagulation — Death-movements of flowers — 

 Approximate constancy of death-point of florets in acapitulum — Definite 

 interval between death-point and discoloration-point — Translocation of 

 . discoloration-point by various agencies — Thermographs of regional 

 death — Thermograph of local fatigue — Thermographic investigation of 

 electrotonic excitation ...... . . . . .176 



PART III.— EXCITABILITY AND 

 CONDUCTIVITY 



CHAPTER XVI 



ON EXCITATORY POLAR EFFECTS OF CURRENTS 



Hydro-mechanical theory of excitation in plants — Theory of protoplasmic 

 change — Crucial tests applied by means of polar excitation — Mono-polar 

 and Bi-polar methods of excitation — Advantages of study of polar 

 excitation in plant -tissues as compared with animal — Effects of feeble 

 E.M.F. — Effect of moderately high E.M.F.— Experiments with highly 

 excitable tissues . . . . . . . . . . .189 



CHAPTER XVII 



ON CONDITIONS OF REVERSAL OF NORMAL POLAR EFFECTS 

 IN LIVING TISSUES 



Effect of high E.M.F, — Effects at two stages, A and B — Experimental 

 verification of A stage effect — Similar effects seen in protozoa— Experi- 

 mental verification of complete reversal at B stage — Law of polar effects 

 under high E.M.F. — Investigation on polar effects by death-response — 

 Reversal of polar effects as due to fatigue, or tissue-modification — In- 

 vestigation of polar effects by glow-response of fireflies .... 200 



CHAPTER XVIII 



ON CONDUCTIVITY AND EXCITABILITY 



Receptive excitability, conductivity, and motile excitability— Molecular 

 Model — Modification of motile excitability : (a) by anaesthetics — (/>) by 



