Plant Response as a Means of Physiological Investigation

83. The Thermometric Spiral and Optic Lever of the Morograph . . 165 85. Thermo-mechanical Curve obtained Photographically (Coronal Fila- 86. Thermo-mechanical Curve of Two Different Specimens of Style of Datura alba, obtained from Flowers of the same Plant . . . 1 69 87. Thermo-mechanical Records of Young Specimen of Spirogyra ; Older 89. Diagrammatic Representation of Mono-polar Excitation . . . 193 92. Make-kathode and Break-anode Effects in Biophytum . . .195

93. Record of Responses of Leaflet of Biophytum, showing Responses occurring at Kathode at Make and not at Break ; and at Anode at Break and not at Make . . . . \ . . . . 196 94. Effects of Ascending and Descending Currents, on Highly Excitable 95. Molecular Model Exhibiting Excitability at the Receptive Area ; Conductivity of Intervening Region ; and Mechanical Response 96. Effect of Ether in the Abolition of Motile Excitability . . . 220 97. Experimental Demonstration of Effects of Cold and Anesthetics in

98. Diagrammatic Representation of Experiment on Biophytum . . 224 100. Experiment showing the Transmission of Excitatory Wave through 10 1. Demonstration of Simultaneous Opposite Effects of Anode and 102. Diagrammatic Representation of Electrical Connections in Mimosa to Exhibit Variation of Motile Excitability, induced by Anode and Kathode . . . 235 104. Diagrammatic Representation of Electrical Connections for Determination of Velocities of Centrifugal and Centripetal Transmissions . 242

105. Curve showing Decline in Heights of Responses, with Diminishing 106. Electrotactile Method for Detection of Excitatory Wave during 108. Experimental Arrangements for Simultaneous Recording of Mechanino. Photographic Record of Response of Mimosa, Exhibiting the Latent Hi. Electric Spark Record, showing Increase of Latent Period by Fatigue, 112. Response of Biophytum ; Electrical Stimulus having been Applied 113. Additive Effects seen in Responses of Biophytum to Stimuli which

114. Multiple Electrical Responses due to Single Strong Stimulus . . 280 115. Multiple Electrotactile Response in Stem of Mimosa, due to Single 116. Multiple Mechanical Response of Biophytum, due to a Single 119. Multiple Response in Biophytum, showing Cyclic Groupings of 1 20. Multiple Response in Biophytum, showing Cyclic Groupings . . 286 123. Multiple Response of Biophytum under the Continuous Action of 124. Induction of Autonomous Response in Biophytum, at Moderately

125. Experimental Apparatus for Making Records of Pulsation of Desmo- 127. Photographic Record of Uniform Pulsations in Desmodium . . . 318 128. Displacement of Mean Position of Vibration of Desmodium Leaflet 129. Method of Application of Chemical Agent to Cut End of Petiole . 321 130. Photographic Record of Effect of Ether Vapour, Large Dose . . 324 132. Photographic Record of Effect of Carbonic Acid Gas . . . 325 133. Photographic Record of Effect of Copper Sulphate Solution Applied

134. Spark -record of Single Pulsation in Leaflet of Desmodium . . 327 135. Photographic Records of Autonomous Pulsations in Desmodium, showing Increase of Amplitude and Decrease of Frequency, with Lowering of Temperature 332 136. Effect of Lowering of Temperature in Producing Increase of Amplitude and Decrease of Frequency in Pulsation of Frog's Heart . 333 137. Photographic Record of Pulsations of Desmodium during Continuous 138. Record of Pulsations of Desmodium at Different Temperatures . 334

139. Record of Pulsations of Frog's Heart at Different Temperatures 140. Effect of Cooling to Thermo-tonic Minimum on Pulsation of Desmo- 142. Photographic Record of Pulsation of Desmodium, showing Subpulses 143. Photographic Record of Cyclic Groupings in Autonomous Pulsations 144. Photographic Record of Autonomous Pulsation of Desmodium, 145. Record showing that Rhythmic Tissue of Desmodium is Incapable of 146. Curve showing Relation between Temperature and Period of

147. Curve showing Relation between Temperature and Period of Pulsa- 1 50. Simple Alternation of Pulsation in Frog's Heart (Pembrey and Phillips) 350 151. Effect of Barium Chloride Solution on Desmodium . . 351 152. Arrest of Beat of Ventricle of Frog at Diastole by Application of 153. Systolic Arrest of Heart-beat by Dilute NaHO Solution (Gaskell) . 352 154. Arrest of Desmodium Pulsation at 'Diastole' by Application of 155. Arrest of Pulsation of Desmodium at 'Systole' by Application of

1 56. Diagrammatic Representation of the Shoshungraph .... 365 159. Curve showing Normal Suction at 230 C, Increased Suction at 350 C, and the After-effect persisting on Return to Normal Temperature 375 161. Record obtained by Method of Hydrostatic Balance of Successive 162. Record, obtained by Method of Hydraulic Balance, of Successive 166. Record showing Recovery to be Hastened by the Increase of Internal Activity which is caused by Application of Warm Water to the Roots 401

167. Diagrammatic Representation of Balanced Crescograph . . . 414 168. Complete Apparatus for Crescographic Record under Ordinary and 170. Responses of Leaf of Artocarpus to Thermal Stimulation . . 420 171. Renewal of Growth-pulsation by Thermal Stimulus in Tamarindus 172. Initiation of Erectile Response in Leaf by Supply of Water to partially 173. Initiation of Growth-pulsation by Small Supply of Water to 174. Curve showing Relation between Internal Hydrostatic Pressure and

175. Photographic Record showing the Slow Pulsations of Large Amplitude of Desmodium Leaflet at 300 C. to become very much Quickened and Reduced in Amplitude at 420 C 431 177. Photographic Record of Responses of Mature Style of Datura alba 178. Photographic Record of Responses of Style of Datura alba in which 179. Photographic Record of Response of Growing Style of Datura alba 1 80. Balanced Record of Response in Growing Peduncle of Eucharis 181. Semicircular Electrolytic Rheostat interposed in Heating Cir-

182. Record of Growth in Crinum at Temperature of 340 C. and 183. Thermo-crescent Curve of Growth in Crinum Lily under Continu- 184. Curve showing Relation between Temperature and Rate of Growth, 185. Series of Responses of Growing Organ of Crinum Lily, taken under Balanced Conditions at Three Different Temperatures . . . 460 186. Curve showing the Relation between Stimulus and Response in the 187. Continuous Photographic Record of Autonomous Pulsation of Des-

188. Hydrometric Apparatus for Recording Continuous Variation of Rate 189. Photographic Record showing Variation of Rate of Transpiration in 190. Continuous Photographic Record of Variation of Rate of Growth in Four Days' Old Seedling of Oryza sativa, from 3 p.m. till 9 a.m., that is during Eighteen Hours 473 191. Continuous Photographic Record of Variation of Rate of Growth in Seedling of Tamarindus indica, a Fortnight Old, from 3 p.m. to 194. Excitatory Effect of Dilute Solution of Sodium Carbonate on

195. Acceleration of Growth by Application of Solution of Sugar . . 482 197. Unbalanced Record showing Action of Acid in Causing Relaxation 198. Unbalanced Record showing the Action of Alkali, and the Antago- 199. Effect of Strong Solution of NaCl on Rate of Growth, as Modified by 200. The Effect of Different Constitutions in Determining the Resistance Offered to Poisons. The Action of 5 per Cent. Solution of Copper Sulphate 487 201. The Effect of Favourable Induced Constitution in Enabling Plant to

Shake off Result of Toxic Dose of Copper Sulphate . . . . 487 202. Opposite Effects of Large and Small Doses of Poison . . . 488 203. Diagrammatic Representation showing Differential Effect of Weight 204. Diagrammatic Representation of a Multicellular Organ . . . 495 205. Diagrammatic Representation of Experiment showing Curvature Induced by Unilateral Pressure Exerted by Particles . . . 497 206. Record of Responsive Curvature induced in Crinum under Experi-

207. Record of Apogeotropic Response in Scape of Uriclis Lily . . . 500 208. Response Records showing Differences in Rate of Curvature 209. Diagrammatic Representation of Different Positions of a Single Cell, according as the Specimen is held at an Angle of 450 or 1 350, showing Consequent Redistribution of Statoliths (after F. Darwin) 502 210. Effect on Apogeotropic Movement of Application of Ice-cold Water to Upper and Lower Surfaces alternately of a Horizontally laid Crinum Lily .......... 504

211. Effect on Apogeotropic Movement of Temporary Applications of Cold alternately to Upper and Lower Surfaces of Horizontally laid Scape of Uriclis Lily . . . . . . . . 505 212. Experimental Connections for obtaining Electrical Response due to 213. Record of Positive Electrical Variation, indicating Positive Turgidity - Variation (represented by Down Curve), induced in Growing Region by Moderate Stimulation on same side of Tip . . . 517 214. Record showing Galvanometric Positivity subsequently Neutralised

under Transmission of True Excitatory Effect, due to Continuance 215. Record showing Neutralisation and Reversal of Electrical Response at Responding Region, under Strong Stimulation of Tip . . . 518 216. Record showing Negative Electrical Response represented by Up Curve, indicating Negative Turgidity -Variation due to Direct Stimulation . . . . . . . . . .518 217. Record showing Positive Electrical Variation indicating Positive Turgidity- Variation of Distal Point, under Moderate Stimulation of Proximal ........... 519

218. The Relative Electrical and Turgidity Variations of two Diametrially Opposite Points when Strong and Long-continued Stimulus 219. Mechanical Responses of Shoot and of Root to Unilateral Stimulus 220. Mechanical Response of Root of Bindweed to very strong Unilateral 221. Mechanical Responses of Peduncle of Crocus and Root of Bindweed to Unilateral Thermal Stimulation at the Growing Region . 527 222. Diagram showing the various Responsive Effects induced at the

223. Experimental Arrangement for obtaining Records on Smoked Drum of Responses given to Direct and Indirect Stimulation by Leaf of Mimosa ... . . . . . . 530 225. Erectile Response of Leaf of Mimosa due to Transmission of Indirect Effect to Distal Side, when Proximal is Stimulated . . . . 532 227. Curves showing Effect of Amputation on Rate of Growth and 228. Response of Leaf of Mimosa in Favourable Tonic Condition to 229. Response of Leaf of Mimosa in Ordinary Tonic Condition to the

Chemical Stimulus of 10 per Cent. Solution of Salt . ... 552 230. Polar Effects of Currents due to Localised Application on Upper . 231. Effects of Anode and Kathode on Variation of Rate of Growth in Root of Bindweed exhibited by Balanced Growth-record . . . 557 232. Responsive Curvature in Scape of Crinum Lily by Unilateral 233. Effect in Acceleration of Rate of Growth of Seedling of Oryza sativa 234. Longitudinal Contraction and Retardation of Growth under Light in

235. Balanced Record of Variation of Growth in Flower-bud of Crinum 236. Oscillatory Response of Arsenic acted on Continuously by Hertzian 237. Multiple Response to Light of Terminal Leaflet of Desmodium . . 584 238. Response of Terminal Leaflet of DesmodiumAo Strong Light from 239. Response of Terminal Leaflet of Desmodium to Sunlight acting from 240. Diagrammatic Representation 01 the Magnetically Controlled 241. Heliotropic Chamber and Magnetically Controlled Recorder . . 591

246. Positive Heliotropic Movement of Terminal Leaflet of Desmodium Converted by Strong and too Long-continued Stimulus of Light into Oscillatory Movement 604 248. Responses to Successive Uniform Stimuli of Thermal Radiation in 249. Response of Hypocotyl of Tamarindus indica to Continuous Stimu- 251. Response to Diurnal Light and Darkness of Plagiotropic Stem of 252. Response to Daily Periodic Light and Darkness of Plagiotropic Stem 253. Positive Heliotropic Response of Leaflet of Robinia to Sunlight

254. Positive Heliotropic Response of Leaflets of Erythrina indica . . 629 255. Responses of Mimosa to Sunlight of not too long Duration . . . 631 256. Response of Pulvinus of Mimosa to Action of Continuous Light from 258. Negative Multiple Response in Biophytum when Acted on from 260. Movement of Terminal Leaflet of Desmodium placing itself Parallel 261. Curve showing Time-relations of the Responsive Angular Movement of Terminal Leaflet of Desmodium under Light, as represented in

262. Record showing that Lamina is not the Perceptive Organ . .651 263. Positive Heliotropic Movement of Leaf of Mangifera indica under 264. Negative Heliotropic Response of Leaves of Artocarpus under Sun- 265. Torsional Response of Terminal Leaflet of Desmodium under the 267. Torsional Response of Leaf of Mimosa when Laterally Stimulated 268. Torsional Response of Leaf of Mimosa to Lateral Chemical 269. Torsional Response of Complex Strip of Ebonite and India-rubber

270. Records showing Modification of Torsional Response under Induced Variations of Differential Excitabilities in Pulvinus of Mimosa . 662 271. Records showing Torsional Response to Geotropic Stimulus and Induced Modifications in Terminal Leaflet of Erythrina indica . 666 272. Retardation and Reversal of Normal Torsional Movement by the 273. Photographic Record of Diurnal Movement of Petiole of Biophytum 274. Continuous Records of the Diurnal Movement during Thirty-six

275. Initiation of Multiple Response in Lateral Leaflet of Desmodium 276. Photographic Record of Autonomous Pulsations in Lateral Leaflet of Desmodium gyrans under Action of Sunlight, showing Periodic Reversals ........... 692 278. Diagrammatic Representation of a Windmill with Attached Dynamo Responsive movements in plants --Work done by plant — Plant as a machine — Indicator-diagrams -Physiological response-curves— Pulse-records— Cardiagrams — Modification of pulse by poison and other agencies — Automatic response in plants— Optical Lever Recorder— Effect of external agencies on automatic pulse-beat in plants.

From the moment when the germinating seedling bursts its seed-coat, a complex series of movements is initiated. The radicle turns downwards, the plumule up. Underground, the root gropes its way towards moist places, and contrives to avoid hard stones and obstacles. Above ground, the stem is seen to bend, as if in search of light. Tendrils twine about a support. These, amongst many visible movements, are striking enough, but within the unruffled exterior of the plant-body there are others, energetic and incessant, which escape our scrutiny.

Now all these activities are but so many expressions of the response of the plant to the various stimuli by which the living organism is constantly being excited. The plantorgan sometimes responds locally to the direct impact of stimulus, and at other times the effect is conveyed away by conducting elements analogous to nerves, and the responsive changes are manifested at a distance. Thus the most varied and important functions of plant-life are brought about by the power of the tissue to respond to stimulus, that is to say, by the irritability of the plant-cells.