CONTENTS XVll 



PAGE 



organs — Classification of principal types of response — Modifica- 

 tion of response by tonic condition by point of application, 

 by intensity of stimulus, and by differential excitability 

 of the organ — Continuity between phototropic and photonastic 

 movements . . . • • • • • • '157 



CHAPTER XVI 



RADIO-THERMOTROPISM 



Antagonism between thermal and radio-thermal effects — Radio- 

 thermal Stimulator — Effect of indirect stimulation by thermal 

 radiation — Positive radio-thermotropism — Dia-thermotropism — 

 Negative thermotropism — Response of root to thermal radia- 

 tion — Continuity between positive, dia-, and negative radio- 

 thermotropism . . . . • • • • • ^74 



CHAPTER XVn 



RESPONSE OF PLANTS TO WIRELESS STIMULATION 



Effect of high-frequency alternating field of electric force on plants — • 

 Response of IMimosa — Effect of rapidly alternating field on 

 gro\vi:h — Acceleration of grou-th under moderate stimulation — 

 Revival of gro\\'th under high-tension alternating current — 

 Retardation of growth under stronger stimulation — Response to 

 wdreless stimulation — The wireless system — Effect of feeble 

 stimulation — Effect of strong stimulation — Acceleration of 

 gro\\i;h in subtonic specimens — Effect of moderate stimulation 

 on active growth . . . . • • • • • 183 



CHAPTER XVni 



DIURNAL MOVEMENTS OF PLANTS 



Movements complicated by the effects of numerous factors — The 

 Self- Recording Radiograph — The Selenium cell — The Wheatstone 

 Bridge — The Galvanograph — Radiogram of variation of light at 

 different hours of day — Irregular variation in stormy weather — 

 Simultaneous record of variation of temperature and of light for 

 24 hours — Effects of variation of light and of temperature . . I95 



CHAPTER XIX 



EFFECT OF RECURRENT LIGHT AND DARKNESS 

 ON MOVEMENTS OF PLANTS 



Method of continuous automatic record of movements for 24 hours 

 — Constant irrigation— Vertical illumination— The Recorder 



