Life Movements in Plants, Volume I

PART I.. Response of Plant Organs.

RESPONSE OF PLANT ORGANS.

I.--THE PROBLEM OF MOVEMENT IN PLANTS.

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Complexity of the problem--Effects of different forms of stimuli--Diverse responses under identical stimulus--Modification of response determined by intensity and point of application of stimulus, and tonic condition of organ--Response of pulvinated and growing organs--Necessity for shortening the period of experiment 1

II.--THE “PRAYING” PALM TREE.

Description of phenomenon--The Recording apparatus--Record of diurnal movement of the tree--Universality of tree movement--Cause of periodic movement--Periodic movement of trees, and diurnal variation of moto-excitability in Mimosa pudica--Relative effects of light and temperature--Physiological character of the movement--Transpiration and diurnal movement--Diurnal movement in inverted position--Effect of variation of temperature on geotropic curvature--Reversal of natural rhythm by artificial variation of temperature 5

III.--ACTION OF STIMULUS ON VEGETABLE TISSUES.

Different types of Response Recorders--Response of a radial organ--Response of an anisotropic organ--Response of pulvinus of Mimosa pudica--Tabular statement of apex time and period of recovery in different plants--Response of pulvinus of Mimosa to variation of turgor--Different modes of stimulation 31

IV.--THE DIURNAL VARIATION OF EXCITABILITY IN MIMOSA.

Apparatus for study of variation of excitability--Uniform periodic stimulation--The Response Recorder--Effects of external condition on excitability--Effects of light and darkness--Effect of excessive turgor--Influence of temperature--Diurnal variation of excitability--Effect of physiological inertia 43

V.--RESPONSE OF PETIOLE-PULVINUS PREPARATION OF MIMOSA.

Effect of wound or section in modification of normal excitability--The change of excitability after immersion in water--Quantitative determination of the rate of decay of excitability in an isolated preparation--Effect of amputation of upper half of the pulvinus--Effect of removal of the lower half--Influence of weight of leaf on rapidity of responsive fall--The action of chemical agents--Effect of “fatigue” on response--The action of light and darkness on excitability 73

VI.--CONDUCTION OF EXCITATION IN PLANTS.

Hydro-dynamic versus physiological theory of conduction of excitation--Arrest of conductivity by physiological blocks--Convection and conduction of excitation--Effect of temperature on velocity--Effect of season--Effect of age--Effect of dessication of conducting tissue--Influence of tonic condition on conduction--Effect of intensity of stimulus on velocity of transmission--Effect of stimulus on sub-tonic tissues and tissues in optimum condition--Canalisation of conducting path by stimulus--Effect of injury on conductivity 97

VII.--ELECTRIC CONTROL OF EXCITATORY IMPULSE.

Method of conductivity-balance--Control of transmitted excitation in Averrhoa bilimbi by electric current--‘Uphill’ transmission--Transmission ‘downhill’--Electric control of nervous impulse in animal--Directive action of current on conduction of excitation--Effects of direction of current on velocity of transmission in Mimosa--Determination of variation of conductivity by method of Minimal Stimulus and Response--Influence of direction of current on conduction of excitation in animal nerve--Variation of velocity of transmission--After-effects on Heterodromous and Homodromous currents--Laws of variation of nervous conduction under electric current 107

VIII.--EFFECT OF INDIRECT STIMULUS ON PULVINATED ORGANS.

Conduction of excitation--Dual character of the transmitted impulse--Effect of distance of application of stimulus--Periods of transmission of positive and negative impulses--Effects of Direct and Indirect stimulus 135

IX.--MODIFYING INFLUENCE OF TONIC CONDITION ON RESPONSE.

Theory of assimilation and dissimilation--Unmasking of positive effect--Modification of response under artificial depression of tonic condition--Positive response in sub-tonic specimen 141

PART II.. Growth and Its Responsive Variations.

GROWTH AND ITS RESPONSIVE VARIATIONS.

X.--THE HIGH MAGNIFICATION CRESCOGRAPH FOR RESEARCHES ON GROWTH.

Method of high magnification--Automatic record of the rate of growth--Determination of the absolute rate of growth--Stationary method of record--Moving plate method--Precaution against physical disturbance--Determination of latent period and time-relations of response--Advantages of the Crescograph--Magnetic amplification--The Demonstration Crescograph 151

XI.--EFFECT OF TEMPERATURE ON GROWTH.

Method of discontinuous observation--Method of continuous observation--Determination of the cardinal points of growth--The Thermocrescent curve--Relation between temperature and growth 173

XXII.--EFFECT OF CHEMICAL AGENTS ON GROWTH.

Effect of stimulants--Effect of anæsthetics--Action of different gases--Action of poisons 183

XIII.--EFFECT OF VARIATION OF TURGOR AND OF TENSION ON GROWTH.

Response to positive variation of turgor--Method of irrigation--Effect of artificial increase of internal hydrostatic pressure--Response to negative variation of turgor--Method of plasmolysis--Effect of alternative variations of turgor on growth--Response of motile and growing organs to variation of turgor--Effect of external tension 188

XIV.--EFFECT OF ELECTRICAL STIMULUS ON GROWTH.

Effect of intensity--Effect of continuous stimulation--Continuity between ‘incipient’ and actual contraction--Immediate effect and after-effect 195

XV.--EFFECT OF MECHANICAL STIMULUS ON GROWTH.

Effect of mechanical irritation--Effect of wound 200

XVI.--ACTION OF LIGHT ON GROWING ORGANS.

Method of experiment--Normal effect of light--Determination of the latent period--Effect of intensity of light--Effect of continuous light--Effects of different rays of the spectrum 205

XVII.--EFFECT OF INDIRECT STIMULUS ON GROWTH.

Mechanical and electrical response to Indirect Stimulus--Variation of growth under Indirect Stimulus--Effects of Direct and Indirect Stimulus 213

XVIII.--RESPONSE OF GROWING ORGANS IN STATE OF SUB-TONICITY.

Theory of assimilation and dissimilation--Unmasking of positive effect--Modification of response under artificial depression of tonic condition--Positive response in sub-tonic specimen--Abnormal acceleration of growth under stimulus--Continuity between abnormal and normal responses--Positive response to sub-minimal stimulus 219

XIX.--RESUMPTION OF AUTONOMOUS PULSATION AND OF GROWTH UNDER STIMULUS.

Resumption of pulsatory activity of Desmodium leaflet at standstill--Renewal of growth under stimulus--General laws of effects of Direct and Indirect Stimulus 227

XX.--ACTION OF LIGHT AND WARMTH ON AUTONOMOUS ACTIVITY.

The Oscillating Recorder--Record of pulsation of Desmodium gyrans--Effect of diffuse light in diminution of amplitude and reduction of diastolic limit of pulsation--Antagonistic action of warmth in reduction of systolic limit 233

XXI.--A COMPARISON OF RESPONSES IN GROWING AND NON-GROWING ORGANS.

Contractile response of growing and non-growing organs--Time-relations of mechanical response of pulvinated and growing organs--Similar modification of response under condition of sub-tonicity--Opposite effects of Direct and Indirect stimulus--Exhibition of negative electric response under Direct, and positive electric response under Indirect stimulus--Similar modification of autonomous activity in Desmodium gyrans and in growing organs under parallel conditions--Similar excitatory effects of various stimuli on pulvinated and growing organs--Similar discriminative excitatory effects of various rays in excitation of motile and growing organs--Action of white light--Action of red and yellow lights--Action of blue light--Action of ultra-violet rays--Action of infra-red rays--Diverse modes of response to stimulus--Mechanical response--Electromotive response--Response by variation of electric resistance 239

ILLUSTRATIONS.

FIGURE. PAGE.

1. Photographs of morning and evening positions of the ‘Praying Palm’ 7

2. The Recording Apparatus 9

3. Record of diurnal movement of the ‘Praying Palm’ 11

4. " " Sijbaria Palm 12

5. Curve of variation of moto-excitability in Mimosa pudica 17

6. Effect of physiological depression on diurnal movement of Arenga saccharifera 19

7. Record of diurnal movements of young procumbent stem of Mimosa pudica 26

8. Erectile response of Basella to gradual fall of temperature 28

9. Responsive fall of Basella to gradual rise of temperature "

10. Response of a straight tendril of Passiflora 33

11. Response of a hooked tendril of Passiflora 35

12. Response of pulvinus of Mimosa pudica 36

13. " " Mimosa to variations of turgor 40

14. Diagram of complete apparatus for record of diurnal variation 46

15. The Oscillator 50

16. Effect of cloud on excitability of Mimosa 52

17. Effect of sudden darkness 53

18. Effect of change from darkness to light 54

19. Effect of enhanced turgor 55

20. Effect of moderate cooling 56

21. Effect of application of intense cold 58

22. Effect of temperature above the optimum 58

23. Twenty-four hours’ record of excitability of Mimosa 59

24. Midday record from noon to 3 P.M. 62

25. Evening record from 6 to 10 P.M. 63

26. Morning record from 8 A.M. to 12 noon 64

27. Diurnal variation of excitability showing marked nyctitropic movement 65

28. Diurnal curves of temperature and of corresponding variation of excitability of Mimosa 68

29. Diurnal variation of excitability of a summer specimen 70

30. The Resonant Recorder 76

31. Variation of excitability after section 80

32. Effect of amputation of upper half of pulvinus of Mimosa 84

33. Response of Mimosa after amputation of lower half of pulvinus 86

34. Effect of weight on rapidity of fall 87

35. Stimulating action of Hydrogen peroxide 88

36. Incomplete recovery under the action of BaCl_{2} and transient restoration under tetanisation 89

37. Antagonistic action of alkali and acid 90

38. Fatigue due to shortening of recovery-period 91

39. Effect of constant current in removal of fatigue 92

40. Stimulating action of light and depressing action of darkness 94

41. Action of glycerine in enhancing speed and intensity of transmitted excitation in Mimosa 102

42. Effect of injury in depressing conductivity in normal specimen 104

43. Effect of injury in enhancing conductivity in a subtonic specimen 105

44. Diagram of experimental arrangement for conductivity control in Averrhoa bilimbi 109

45. Diagram of complete experimental arrangement for conductivity control in Mimosa pudica 116

46. Record showing enhanced velocity in ‘up-hill’ and retarded velocity in ‘down-hill’ transmission 121

47. Direct and after-effect of heterodromous and homodromous currents 124

48. Diagram of experimental arrangement for variation of conductivity of animal nerve 126

49. Effect of heterodromous and homodromous current in inducing variation of conductivity in nerve 127

50. Record of ineffectively transmitted salt-tetanus becoming effective under heterodromous current 129

51. Direct and after-effect of homodromous current 131

52. Effect of indirect electric stimulus on the responding leaflet of Averrhoa 136

53. Staircase responses of sub-tonic specimen of Mimosa to electric shock 145

54. Staircase responses of sub-tonic specimen of Mimosa to light 147

55. Positive, diphasic, and negative responses of extremely sub-tonic specimen of Mimosa to successive light stimuli 147

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