XXViii LIST OF ILLUSTRATIONS 



FIG. 



PAGE 



167. Geotropic response of petiole of Tropaeolum . . . 285 



168. The complete geotropic curve (Crinum) .... 287 



169. Diagram of response to light or gravity (Crinum) . . 288 



170. Additive effect of photic stimulus ..... 288 



171. Geotropic curve of a spring- and a winter specimen of 



Tropaeolum ......... 295 



172. Effect of Chloroform on geotropic response .... 296 



173. Effect of Chloroform on geotropic response of the terminal 



leaflet of Desmodium ....... 297 



174. Effect of Ether in enhancing geotropic response (petiole of 



Tropaeolum) ........ 298 



175. Effect of Ether vapour on geotropism .... 299 

 176.) Effect of CO2 on geotropic response of a winter-specimen 

 177.) and of a spring-specimen of Tropaeolum .... 300 



178. Effect of CO2 on geotropic response of Tropaeolum . . 301 



179. Method of record of geotropic response of j\Iimosa . . 303 



180. Effect of CO2 on geotropic response of Mimosa . . . 304 



181. Effect of CO2 on geotropic response of Erythrina indica . 304 



182. Diagram of arrangement for recording torsional response to 



geotropic stimulation (Mimosa) ..... 306 



183. Clockwise torsional response under geotropic stimulation . 307 



184. Anti-clockwise torsional response under geotropic stimulation 307 



185. Additive effect of stimulation by gravity and by light . 309 



186. Algebraical summation of geotropic and phototropic action . 309 



187. Comparative balancing effects of white and red light . .310 



188. Effect of coal gas on photo-geotropic balance . . • 311 



189. Diagrammatic representation of a multicellular organ laid 



horizontally and exposed to geotropic stimulation . - 3^4 



190. Experimental arrangement for subjecting shoot to geotropic 



stimulation . . . . . . . • -315 



191. Geo-electric response of the physically restrained scape of 



Eucharis Lily . . . . . . • .316 



192. Successive responses (Polianthes tuberosa) .... 3^6 



193. Diagrammatic representation of geo-electric response . .319 



194. Diagrammatic representation of the Method of Axial Rotation 



and of Vertical Rotation ...... 320 



195. Geo-electric response of Anthurium ..... 322 



196. Diagrammatic representation of the geo-perceptive layer in 



unexcited vertical and in excited horizontal position . 327 



197. The Electric Probe . . . . . . • .328 



198. Intensity of geo-electric response at different depths in the 



petiole of Tropaeolum ....... 332 



199. Curve showing distribution of geotropic excitability . . 335 



200. Photo-micrograph of transverse section of upper half of hori- 



zontally laid stem of Impatiens . . . • .337 



201. Longitudinal section of upper and lower halves of geo- 



tropically curved stem of Eclipta . . . . • 337 



202. Distribution of geotropic excitability in the peduncle of 



Nymphaea ......••• 34° 



203. Distribution of geotropic excitability in the shoot of Bryo- 



phyllum ......••• 34° 



