Plant Response as a Means of Physiological Investigation

of response— (4) The effect of barium salt — (5) The antagonistic actions of acid and alkali — Identity of rhythmic phenomena in animal and vegetable tissues .......... 344 Inadequacy of existing theories of ascent of sap — General considerations regarding cellular activity and resultant propulsion of water — The Shoshungraph — Balanced Shoshungraph for determining variations of suction — Hydrostatic and Hydraulic Methods of Balance . . . 359 Effect of temperature on suction by three methods of inquiry: (1) Un- balanced method of Shoshungraph : (a) Action of cold — (b) Action of moderate rise of temperature — (2) Method of Hydrostatic Balance : (a) Action of cold — Reversal of normal direction of flow — (b) Action of warm water — (3) Method of Hydraulic Balance — (a) Action of cold — (d) Effect of warm water — Explanation of suction when the root is killed by boiling water — Stimulation renews suctional activity in plant whose suction has come to a standstill — Osmotic versus excitatory action — Abolition of suction by poison — Suctional activity continued until whole plant is killed by poison . . . . . . . . 372

The mechanics of the ascent of sap : (a) Uni-directioned flow — (/>) Initiation of multiple rhythmic excitations — Connection between conduction of excitation and conduction of sap — Rapidity of ascent of sap accounted for by stimulatory action — Positive and negative pressures due to one cause — (1) Positive pressure— (2) Negative pressure — (3) Irregular variations of pressure — Direct conduction and conduction by relays — Excretion of water — Excretion of nectar — Translocation of organic foodsubstances — -Mechanical response to suctional activity — Effect of warmth — Effect of cold — Explanation of the drooping of leaves during frost — Explanation of response and recovery — Antagonistic actions of internal energy and external stimulus 389

The simple Crescograph — The Balanced Crescograph — Rhythmic growthresponse — Growth -response and excitatory response — Law of direct and indirect effects of excitation — Positive turgidity-variation as indirect effect of excitation — Mechanical test — Significance of ' inner stimuli ' . . 409 Characteristics common to growth and to other forms of rhythmic response : (1) Periodic groupings— (2) Effect of external stimulus in renewal of growth when at temporary standstill — (3) Renewal of growth-pulsation by positive turgidity-variation — (4) Effect of increased internal hydrostatic pressure— (5) Effect of ascent of sap on growth — Effect of temperature on growth — Comparison of various types of multiple response — Effect of external tension on growth — Effect of direct application of stimulus on the growing region — Similarities between motile and growth responses — Direct and indirect effects of stimulus, and laws of growth . 424

General consideration of difficulties of accurate determination of effects of temperature on growth — Four accurate methods : (1) Method of discontinuous observations— Accurate regulation of temperature by electrolytic rheostat — (2) Method of continuous observations — Thermo-crescent curve — Determination of the optimum point — (3) Method of balance — (4) Method of excitatory response — Translocation of the optimum point 441 ON AN ATTEMPT TO DETECT AND MEASURE LATENT STIMULUS," AND ON THE STUDY OF PERIODIC AFTER-EFFECTS

Positive and negative after-effects — Extreme delicacy of the Method of Balance — Detection of absorbed stimulus by negative after-effect — Constancy of sum of direct and indirect after-effects — Latent component almost vanishing above the optimum — Variation of receptivity — Direct and indirect response of plant in sub-tonic condition — Table showing direct and indirect effects at different temperatures — Is the change induced by stimulus always of an explosive chemical character ? — Relation between stimulus and response in different tonic conditions— Aftereffect—Factors which determine periodic after-effects: (i) Stimulus of light — (2) Temperature — (3) Chemical stimulus— (4) Turgidity — Continuous photographic record of the pulsations of Desmodium — Record of periodic variation of rate of growth — Continuous photographic record of periodic variations of transpiration — Continuous photographic record of the variation of the rate of growth — Annual rings and seasonal periodicity ........ ... 456

General consideration of the problem — * Constitution ' and the elements which determine it — Methods of investigation — Action of carbonic acid gas — Action of ether — Effect of solution of sodium carbonate — Effect of solution of sugar — Effect of alcohol — Effect of acids — Effect of alkali — Antagonistic action of alkalis and acids — Action of strong solution of sodium chloride — Effect of poisonous solution of copper sulphate — Opposite effects of the same dose on different constitutions — Opposite effects of large and small doses . . . . . . . -477

Statement of the problem of apogeotropic response — Mode in which stimulation is brought about : radial-pressure theory, and theory of statoliths — Mechanics of responsive movement — Experiment demonstrating responsive curvature as brought about by unilateral pressure of particles — Record of curvature induced by gravitation — Record of different rates of curvature when specimen is held at angles of 450 and 1350 to the vertical — Determination of the true character of apogeotropic response —Responsive curvature of acellular organs — Curvature of grass haulm under gravity — Growth of grass haulm on a klinostat .... 493

Difference between shoot and root in their response to stimulus of gravity — Difference in character of response between tip and growing region of root — Scope of the investigation — Electrical investigation — Responsive results of: I. Longitudinal transmission of effect of stimulus from tip ; (a) Moderate unilateral stimulation ; (b) effect of stronger unilateral stimulation — 2. Direct unilateral stimulation of growing region — Moderately strong stimulus — 3. Transverse transmission of effect of stimulus ; (a) moderate stimulation ; (b) stronger stimulation — Mechanical response inferred from observed electrical response — Tabular statement . . . . . . . . . .512

Scope of the investigation : 1. Mechanical response to unilateral stimulation of the tips of shoot and root : (a) Moderate stimulus — (b) Stronger stimulation — 2. Effect of unilateral stimulus, applied at the responding growing region: (a) Moderate stimulus— (b) Strong or long-continued stimulus — Experiments on the direct and indirect effects of stimulus on Mimosa : (a) Direct stimulation — (b) Indirect stimulation, longitudinal transmission — (c) Indirect stimulation, transverse transmission — The curious response of Arisama— Table showing responsive effects common to pulvini, pulvinoids, and growing organs — Laws of responsive growthcurvature ............ 524

No specific difference as regards their responses, between shoot and root — Darwinian curvature — Localisation of geotropic sensibility at the roottip — Experiments as to whether amputation of root-tip abolishes excitability — The tip of the root the organ of graviperception — The perceptive versus the responding organ — True perceptive region . . 536 General difficulties of the investigation — How to overcome these difficulties — Three distinct methods of testing results : ( 1 ) by variation of longitudinal

growth ; (2) by responsive movement of pulvinus; and (3) by growthcurvature— Method of application of chemical reagent — Effect of alkali — Effect of acid — Effect of copper sulphate— Action of sugar solution— Chemo-tactic movements — Explanation of anomalous osmotic or plasmolytic action — Excitatory versus plasmolytic reaction in pulvinus of Mimosa : (1) Favourable tonic condition— (2) Ordinary tonic condition — Polar effects of currents inducing growth-curvatures — Localised polar effects on pulvinus — Anodic and kathodic effects on longitudinal growth — Generalised law of polar excitation in plants — Galvano-tropic response — The indirect effect of polar excitation— The effect on growth of ' electrification ' of soil 546

Diversity of movements induced by light — Differentiation of responsive movements — Action of light on tissues in sub-tonic condition — Effect of light on pulvinated organs — Effect of diffuse stimulation of light on non-growing radial organs — Retarding effect of light on longitudinal growth — Phenomenon of oscillation under long-continued stimulation — Similarity of responsive reaction under light and under other forms of stimulation ........... 565

Introduction — Theory of de Candolle — Inadequacy of de Candolle's theory — Definition of terms positive and negative — Darwin's theory of modified circum nutation — Response of terminal leaflet of Desmodium — Extreme sensitiveness of some plant-organs to light — Merging of multiple in continuous response — Orientation induced by light — The perceptive region in the terminal leaflet of Desmodium — Heliotropic response in radial organ — Magnetically controlled recorder — Heliotropic response of hypocotyl of Sinapis — Recovery and theory of recti-petality. 579

Incomplete parallelism between actions of light and of gravitation — Theoretical considerations — Recording microscope — Negative heliotropic curvature induced by stimulation of the tips of root and shoot — Intermediate phases between positive and negative heliotropic response : (a) neutralisation by transverse transmission ; (b) neutralisation by transverse transmission, with multiple response — Localised sensitiveness to light and transmission of excitatory effect — Negative heliotropism of a radial organ — Gradual transition from positive to negative, through intermediate phase of neutrality — Apparent heliotropic insensitiveness of certain tendrils — Negative heliotropism of tendril of Vitis . . . 597

Effect of temperature and its variations — Demonstration of fundamental effect of thermal radiation on growth — Response to successive uniform stimuli of thermal radiation — Effect of continuous unilateral stimulation — Effect of electrical waves on growth — Response of Mimosa to electric radiation — Action of high frequency Tesla current .... 614 Photonasty and para-heliotropism — Response of Tropceolum majus — Re- sponses of plagiotropic stems : {a) Mimosa — (b) Ipomosa — (c) Cucurbita — Daily periodic movements of plagiotropic stems — Responsive movements of pulvinated organs — Pulvinated organs showing positive heliotropic movement : (a) Response of terminal leaflet of Desm odium — (b) Response of leaflet of Robinia ~{c) Responsive movements of leaflets of Erythrina indica and Cliloria tematea — The negative heliotropic type of response : (a) Response of pulvinus of Mimosa — (b) Diurnal sleep of Oxalis — (c) Diurnal sleep of Biophytum — Directive versus non -directive action of light — General view of responsive curvatures induced in different organs by unilateral application of light . . . . . . . .621

Difficulty of distinguishing between effect of light and other reactions — Theories of Frank and De Vries — Subsidiary factors: (1) Epinasty and hyponasty ; (2) Effect of gravity ; (3) Effect of suctional activity and of turgescence ; (4) Modification of effect by characteristic limits of flexibility — Discrimination of the part played by heliotropism in the movement of the leaf— Proof of absence of any specific dia-heliotropic tendency in leaves — The lamina not the perceptive organ — Principal types of the response of leaves to stimulus of light — Positive type of response : mango leaf — Negative type of response : leaf of Artocarpus . 640

TORSIONAL RESPONSE TO HELIOTROPIC AND GEOTROPIC STI- MULUS : AUTONOMOUS TORSION AND ITS VARIATIONS Torsional effect — Method of recording torsional response — Torsional response under the lateral action of light — Torsional response to other forms of lateral stimulation — Torsional response of compound strip of ebonite and stretched india-rubber— Modification of torsional response by artificial variation of the relative excitabilities of the two halves — Laws of torsional response — Demonstration of differential geotropic excitation in a dorsi-ventral organ — Torsional response to lateral geotropic stimulation— Modification of torsional geotropic response by artificial variation of differential excitability — Autonomous torsion : Effect of temperature — Effect of light— Effect of electrical current — Effect of gravity — The twining of stems ........ 656

Comparison between nyctitropic and autonomous pulsations — Diurnal movement of plagiotropic stem — Supposed distinction between nyctitropic and other movements of response to stimulus of light — Diurnal response of leaf of Biophytum — Diurnal response of primary petiole of Mimosa — Periodic impulses acting on the leaf — Periodic impulses contributed by the plant as a whole — Other modes of exhibition of diurnal periodicity of hydrostatic tension — Forced vibration and its periodic after-effects — Physical analogue — Impressed periodic vibrations in organ originally radial ............ 676

Investigations on the influence of light on the lateral leaflet of Desmodium gyrans : (a) in sub-tonic condition ; (/>) in normal tonic condition — Changes induced in existing anisotropy of Desmodiam leaflets— Reversal under intense stimulation seen in ail forms of response — The swimming movements of ciliated organisms — Fundamental resemblance between the swimming responses and the ordinary heliotropic responses in radial organs — Phototactic movements : (a) Two natural types of responsive movements ; (6) Responsive movement positive, negative, or intermediate, according to intensity of stimulation — Directive action of light — Thermotaxis — Galvanotaxis — Chemotaxis ..... 689

Responsive contraction— Kunchangraphic records— Direct and indirect effects of stimulation — Various forms of responsive expression ; (a) Lateral motile response by differential contraction ; {b) Suctional response ; (c) Growth-response ; (d) Torsional response ; (e) Death response ; (/) Thermographs of regional death ; [g) Electrical response — Different types of response : {a) Uniform response ; (b) Fatigue ; (c) Staircase response — Excitability — Conductivity — Polar effects of currents — Multiple response — Continuity of multiple and autonomous responses — The ascent of sap ........ 703

Longitudinal growth and its variations, — Effect of temperature on growth — Responsive growth-curvature under unilateral stimulation : — 1. Direct unilateral stimulus on the responding organ : {a) Positive response under moderate stimulation ; (b) Intermediate or neutral response ; {c) Negative response ; (d) Dorsi-ventral positive response ; (e) Dorsi-ventral response which may become negative — 2. Indirect effect of unilateral stimulation : (a) Negative response ; (b) Positive response — Responsive action under stimulus of gravity — Heliotropic action in radial organs — Heliotropic action in plagiotropic and dorsi-ventral organs — Phototactic movements — Nyctitropic movements . . . . 725

Vitalism -Fundamental unity of physiological response in plant and animal — Theory of Darwin — Variation as induced by external forces . . 740 Page 409, line I of analytical contents, for Growth- Recorder read Crescograph. 1. Record of Healthy Adult and Senile Human Pulse (Broadbent) . . 3 2. Effect of Muscarin in arresting Pulsation of Frog's Ventricle (Cushing) 4 5. Death of Plant, and Arrest of Pulsation, by Poison .... 8 6. Death, and Arrest of Pulsation, in Leaflet of Desmodium by Strong

10. Photographic Record of Longitudinal Contractile Response in 11. Differential Lateral Response of Compound Strip . . . .13 14. Diagram of Connections for Stimulation by Condenser Discharge . 18 1 5. Photographic Record of Response and Recovery of Mimosa, taken on 16. Photographic Record of Response in different specimen, taken on a 18. Response of B iophytum to Electric Stimulation . . . . . 24 22. Hydraulic Model for Explanation of Electric Response . . . 31

23. Electrical Response in Plant by Method of Block . . . -32 26. Simultaneous Mechanical and Electrical Responses in Biophytum . . 34 27. The Abnormal Positive preceding the Normal Negative in Mechanical 28. Response of Selenium to the Stimulus of Light . . . . . 39 29. Response of Metal abolished by the action of ' Poison ' (Oxalic Acid) . 40 30. Responses of quickly reacting Biophytitni, and sluggish Philanthns urinaria, under moderate and under stronger Stimulation . . 44

33. Response of Leaves of Ordinary Plants to Electric Stimulation . . 64 34. Alternate opposite-directioned Responses obtained by the successive Unilateral Stimulations of opposite sides of Pistil of Musa . . 68 36. Diagrammatic Representation of Apparatus for Periodic Stimulation 37. Response of Stem of Cuscuta to Electric Stimulation . . • • 77 38. Photographic Record of Responses of Style of Datura alba to Thermal 41. Response of Bifurcated Allium Tube by sudden Collapse . . . 87

43. Response by Coiling of spirally-cut A Ilium Peduncle . . 91 44. Ineffective Stimulus made Effective by Repetition .... 95 46. Mechanical Responses to Stimuli increasing in Arithmetical Progression 96 47. Curve showing Relation between Stimulus and Response . . . 96 48. Increased Electrical Response with Increasing Vibrational Stimuli 50. Photographic Record of Genesis of Tetanus in Mechanical Response of 52. Staircase Effect in Longitudinal Mechanical Response of Plant (Style

53. Fatigue in Longitudinal Mechanical Response of Plant (Style of 54. Fatigue shown in Electrical Response, when sufficient Time is not 55. Alternate Fatigue in Electrical Responses of Petiole of Cauliflower ; in Multiple Electric Responses of Peduncle of Biophytum ; in Multiple Mechanical Responses of Leaflet of Biophytum ; and in Autonomous Responses of Desmodium . . . . . . 106 56. Rapid Fatigue under Continuous Stimulation in Muscle, and in 57. Fatigue under long-continued Stimulation in the Contractile Response

58. Photographic Record of Periodic Fatigue under Continuous Stimulation in Contractile Response (Filament of Uticlis Lily) . . .108 59. Photographic Records of Normal Response of Mimosa to Single Stimulus (upper figure), and to Continuous Stimulation (lower figure) 109 60. Ineffectiveness of Stimuli, owing to Increasing Fatigue, in Mimosa . 113 61. Fatigue-Reversal in Arsenic, under Continuous Stimulation of Hertzian 62. Automatic Record of Fatigue in the Contractile Response of India-

63. Preliminary Staircase Increase, followed by Fatigue, in the Response 64. Preliminary Staircase Increase, followed by Fatigue, in the Response 65. Preliminary Staircase, followed by Fatigue, in the Responses of 66. Staircase Increase in Electrical Response of Petiole of Bryophyllum, 67. Mechanical Response in Tendril of Passiflora in which Growth 68. Effect of Carbonic Acid Gas on Longitudinal Contractile Response . 131 70. Photographic Record showing Effect of Carbon Disulphide in Abolish-

75. Diminution of Response in Eucharis Lily by Lowering of Temperature 140 78. Effect of Rise of Temperature on Electrical Response . . . 144 79. Effect of Rise of Temperature on Longitudinal Contractile Response 80. Effect of Rising and Falling Temperature on the Electrical Response 81. Effect of Cyclic Rise and Fall of Temperature on Longitudinal 82. Determination of Death-point in Allium Tube by Observation of Volumetric Contraction, causing sudden Expulsion of Water . . 157