XX CONTENTS 



CHAPTER XXVII 



EFFECT OF ANAESTHETICS ON GEOTROPIC RESPONSE 



PAGE 



Effect of anaesthetics on growth — Effect of season on geotropic 

 response — Effect of chloroform on geotropic response of growing 

 and of pulvinated organs — Effect of ether on geotropic curvature 

 — Effect of carbonic acid gas on geotropic response of growing 

 organs — Effect on winter- and on spring-specimens — Effect of 

 carbonic acid gas on geotropic response of pulvinated organ- 

 Reversal of geotropic response under continued action of 

 carbonic acid gas . . . • • • • • -293 



CHAPTER XXVIII 



GEOTROPIC TORSION 



Torsional response of dorsiventral organs to lateral geotropic 

 stimulation — Determination of the direction of stimulus of 

 gravity from torsional response — Balance of geotropic by photo- 

 tropic reaction — Comparative balancing effect of white and red 

 light — Effect of coal-gas on photo-geotropic balance . . . 306 



CHAPTER XXIX 



THE GEO-ELECTRIC RESPONSE OF THE SHOOT 



Experimental arrangements for observing geo-electric response— 

 Non-polarisable electrodes — Securing iso-electric condition of 

 electrodes — ^Three different methods of experimentation — The 

 Method of Contact with sensitive and indifferent points — The 

 Method of Axial Rotation— The Method of Vertical Rotation- 

 Characteristics of geo-electric response — The latent period of 

 electric response — Physiological character of geo-electric response 



Relation between angle of inclination and geotropic excitation 



— ^The Law of Sines . . . • • • • • 3 ^ 3 



CHAPTER XXX 



LOCALISATION OF GEO-PERCEPTIVE LAYER 

 BY ELECTRIC PROBE 



Electric excitation at different layers under geotropic stimulation — 

 The Electric Probe — Method of experiment — Prick-reaction — 

 Geo-electric response at different depths in the petiole of 

 Tropaeolum— Maximum excitability at geo-perceptive layer — 

 Decline of geotropic excitability at distance from perceptive 

 layer — Opposite reactions in the upper and lower halves — Method 

 of Transverse Perforation — LocaUsation of geo-perceptive layer — 



