# Life Movements in Plants Vol 1

TRANSACTIONS
OF THE
BOSE RESEARCH INSTITUTE, CALCUTTA,
VOL. I, PARTS 1 & 2, 1918

LIFE MOVEMENTS IN PLANTS

BY

SIR JAGADIS CHUNDER BOSE, Kt., M.A., D.Sc., C.S.I., C.I.E.,

PROFESSOR EMERITUS, PRESIDENCY COLLEGE.
DIRECTOR, BOSE RESEARCH INSTITUTE.

WITH 92 ILLUSTRATIONS

CALCUTTA
BENGAL GOVERNMENT PRESS.
1918

THE BOSE RESEARCH INSTITUTE, CALCUTTA.

 WORKS BY THE SAME AUTHOR RESPONSE IN THE LIVING AND NON-LIVING. With 117 illustrations, 8 vo. 10s. 6d.⁠ 1902 PLANT RESPONSE: AS A MEANS OF PHYSIOLOGICAL INVESTIGATION. With 278 Illustrations, 8 vo. 21s. 1906 COMPARATIVE ELECTRO-PHYSIOLOGY. A PHYSICO-PHYSIOLOGICAL STUDY. With 406 Illustrations, 8 vo. 15s. 1907 RESEARCHES ON IRRITABILITY OF PLANTS. With 190 Illustrations, 8 vo. 10s. 6d. nct 1913 Longmans, Green and Co. London, New York, Bombay and Calcutta.

I dedicated the Institute to the Nation on the 30th November 1917. The fuller investigation of the many ever-opening problems of the nascent science, which includes both Life and Non-Life, are among the main purposes of the Institute. In adding a large auditorium, I have sought permanently to associate the advancement of knowledge with the widest possible civic and public diffusion of it; and this without any academic limitations, henceforth to all races and languages, to both men and women alike, and for all time coming.

It is my further wish that, as far as the limited accommodation would permit, the facilities of this Institute should be available to workers from all countries. In this I am attempting to carry out the traditions of my country, which, so far back as twenty-five centuries ago, welcomed all scholars from different parts of the world within the precincts of its ancient seats of learning, at Nalanda and at Taxilla.

The present time may be regarded as inopportune for any new undertaking, when a great tragedy is hanging over human destiny. But it is at such a crisis that men learn to discriminate the Real from the Unreal, so that they can dedicate themselves to the pursuit of Truth which is eternal.

Since the opening of the Institute I have received much encouragement and help from different provinces of India in this national undertaking. My grateful thanks are due to the gentlemen whose first donations have formed the nucleus of an Endowment Fund, and also to Mr. P. C. Lyon, the retired Minister of Education, Government of Bengal, through whose representation the Government have been pleased to make generous grants in furtherance of research. I am indebted to His Excellency Lord Ronaldshay, Governor of Bengal, for the grant of land for necessary expansion and for his interest in the permanence of the Institute. The Government of India. and the Government of Bengal have also sanctioned six Scholarships for Research students of the Institute.

The Government has also kindly undertaken the publication of the Transactions of the Institute to be issued twice a year. Much time had to he given last year in the organization of the Institute. In spite of this a long series of investigations on the phenomenon of plant movements have been completed in the course of the year. Of these the first series is given in the present volume.

J. C. BOSE.

October 1918

Director.

Sir Jagadis Chunder Bose, Kt., M.A., D.Sc., C.S.I., C.I.R.

Scholars and Research Assistants.

Guruprasanna Das, L.M.S.

Surendra Chandra Das, M.A.

Narendra Nath Neogi, M.Sc.

Basiswar Sen, B.Sc.

Jyotiprakash Sircar, B.Sc., M.B., Ch.B.

Satyendra Nath De, M.Sc.

Lalit Mohan Mukhopadhya, B.Sc. (Nawroji Scholar).

Satyendra Chandra Guha, M.Sc.

Abani Nath Mitter, Superintendent.

Honorary Secretary.

Sudhansu Mohan Bose, M.A., LL.B.

Trustees of the Institute.

Hon'ble Sir Satyendra Prasanna Sinha.

Sudhansu Mohan Bose.

Hon'ble Sir Nil Ratan Sircar.

Board of Managers.

 The Director of the Institute … ${\displaystyle \scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}}$ Ex officio Members. The Superintendent of the Institute

Hon'ble Sir Nil Ratan Sircar.

Satis Ranjan Das.

Sudhansu Mohan Bose.

Dr. Banwari Lal Chaudhuri.

Dr. Prankrishna Acharya.

A representative of Research Scholars.

Visitors.

His Excellency Lord Ronaldshay, G.C.I.E.

Maharaja Sir Manindra Chandra Nandy, K.C.I.E.

Donors.

His Highness the Maharaja Gaekwar of Baroda.

S. R. Bomanji, Bombay.

Mulraj Khatau, Bombay.

Maharaja Sir Manindra Chandra Nandy, K.C.I.E.

Honorary Members.

Lord Rayleigh, O.M., D.Sc., D.C.L., LL.D., F.R.S.

Professor S. H. Vines, F.R.S., University of Oxford.

Professor P. C. Ray, D.Sc., C.I.E.

P. C. Lyon, C.S.I., Fellow, Oriel College, Oxford.

President Stanley Hall, Clark University.

Professor R. A. Millikan, University of Chicago.

Professor R. A. Harper, Columbia University.

Professor Patrick Geddes, University of St. Andrews.

THE VOICE OF LIFE.[1]

I dedicate to-day this Institute—not merely a Laboratory but a Temple. The power of physical methods applies for the establishment of that truth which can be realized directly through our senses, or through the vast expansion of the perceptive range by means of artificially created organs. We still gather the tremulous message when the note of the audible reaches the unheard. When human sight fails, we continue to explore the region of the invisible. The little that we can see is as nothing compared to the vastness of that which we cannot. Out of the very imperfection of his senses man has built himself a raft of thought by which he makes daring adventures on the great seas of the Unknown. But there are other truths which will remain beyond even the super-sensitive methods known to science. For these we require faith, tested not in a few years but by an entire life. And a temple is erected as a fit memorial for the establishment of that truth for which faith was needed. The personal, yet general, truth and faith whose establishment this Institute connnemorates is this: that when one dedicates himself wholly for a great object, the closed doors shall open, and the seemingly impossible will become possible for him.

Thirty-two years ago I chose teaching of science as my vocation. It was held, that by its very peculiar constitution, the Indian mind would always turn away from the study of Nature to metaphysical speculations. Even had the capacity for inquiry and accurate observation been assumed present, there were no opportunities for their employment; there were no well-equipped laboratories nor skilled mechanicians. This was all too true. It is for man not to quarrel with circumstances but bravely accept them; and we belong to that race and dynasty who had accomplished great things with simple means.

FAILURE AND SUCCESS.

This day twenty-three years ago, I resolved that as far as the whole-hearted devotion and faith of one man counted, that would not be wanting, and within six months it came about that some of the difficult problems connected with electric waves found their solution in my Laboratory, and received high appreciation from the leading physicists. The Royal Society honoured me by publishing my discoveries and offering of their own accord an appropriation from the special Parliamentary grant for the advancement of knowledge. That day the closed gates suddenly opened, and I hoped that the torch that was then lighted would continue to burn brighter and brighter. But man’s faith and hope require repeated testing. For five years after this the progress was uninterrupted; yet when the most generous and wide appreciation of my work had reached almost the highest point there came a sudden and unexpected change.

LIVING AND NON-LIVING.

In the pursuit of my investigations I was unconsciously led into the border region of physics and physiology, and was amazed to find boundary lines vanishing and points of contact emerge between the realms of the Living and Non-Living. Inorganic matter was found anything but inert; it also was a-thrill under the action of multitudinous forces that played on it. A common reaction seemed to bring together metal, plant and animal under a general law. They all exhibited the phenomena of fatigue and depression, together with possibilities of recovery and of exaltation, yet also that of permanent irresponsiveness which is associated with death. I was filled with awe at this great generalization; and it was with great hope that I announced my results before the leading scientific society. The results were so unexpected that they provoked incredulity. There were also misgivings about the inherent bent of the Indian mind towards mysticism and unchecked imagination. But in India this burning imagination which can extort new order out of a mass of apparently contradictory facts, is also held in check by the habit of meditation. It is this restraint which confers the power to hold the mind in pursuit of truth, in infinite patience, to wait, and reconsider, to experimentally test and repeatedly verify.

It is but natural that there should be prejudice, even in science, against all innovations; but there were added other difiiculties which it was impossible to remove from this isolating distance. Thus no conditions could have been more hopeless than those which confronted me for the next twelve years. It is necessary to make this brief reference to this period of my life; for one who would devote himself to the search of truth must realize that for him there awaits no easy life, but one of unending struggle. It is for him to cast his life as an offering, regarding gain and loss, success and failure, as one. Yet in my case this long persisting gloom was suddenly lifted. My scientific deputation in 1914, from the Government of India, gave the opportunity of giving demonstrations of my results before the leading scientific societies of the world. This led to a very generous appreciation of my work and the recognition of the importance of Indian contribution to the advancement of the world's science. My own experience told me how heavy, sometimes even crushing, are the difficulties which confront an inquirer here in India; yet it made me stronger in my determination, that I shall make the path of those who are to follow me less arduous, and that India is never to relinquish what has been won for her after years of struggle.

THE TWO IDEALS.

What is it that India is to win and maintain? Has her own history and the teaching of the past prepared her for some temporary and quite subordinate gain? There are at this moment two complementary and not antagonistic ideals before the country. There is first, the individualistic ideal of winning success in all affairs, of securing material efficiency and of satisfaction of personal ambition. These are necessary, but by themselves cannot ensure the life of a nation. Such material activities have brought in the West their fruit, in accession of power and wealth. There has been a feverish rush even in the realm of science, for exploiting applications of knowledge, not so often for saving as for causing destruction. In the absence of some power of restraint, civilization is now trembling in an unstable poise on the brink of ruin. Some complementary ideal there must be to save man from that mad rush which must end in disaster. He has followed the lure and excitement of some insatiable ambition, never pausing for a moment to think of the ultimate object for which success was to serve as a temporary incentive. He forgot that far more potent than competition, was mutual help and co-operation in the schema of life. And in this country through millenniums, there always have been some who, beyond the immediate and absorbing prize of the hour, sought for the realization of the highest ideal of life—not through passive renunciation, but through active struggle. The weakling who has refused the conflict, having acquired nothing, has nothing to renounce. He alone who has striven and won can enrich the world by giving away the fruits of his victorious experience. In India such examples of constant realization of ideals through work have resulted in the formation of a continuous living tradition. And by her latent power of rejuvenescence she has readjusted herself through infinite transformations. Thus while the soul of Babylon and the Nile Valley have trans-migrated, ours still remains vital and with capacity of absorbing what time has brought, and making it one with itself.

The ideal of giving, of enriching, in fine, of self-renunciation in response to the highest call of humanity is the other and complementary ideal. The motive power for this is not to be found in personal ambition but in the effacement of all littlenesses, and uprooting of that ignorance which regards anything as gain which is to be purchased at others’ loss. This I know, that no vision of truth can come except in the absence of all sources of distraction, and when the mind has reached the point of rest. And for my disciples, I call on those very few, who will devote their whole life with strengthened character and determined purpose to take part in that infinite struggle to win knowledge for its own sake and see truth face to face.

The work already carried out in my Laboratory on the response of matter, and the unexpected revelations in plant life, foreshadowing the wonders of the highest animal life, have opened out very extended regions of inquiry in Physics, in Physiology, in Medicine, in Agriculture and even in Psychology. These inquiries are obviously more extensive than those customary either among physicists or physiologists, since demanding interests and aptitudes hitherto more or less divided between them. In the study of Nature, there is a necessity of the dual viewpoint, this alternating yet rhythmically unified interaction of biological thought with physical studies, and physical thought with biological studies. The future worker with his freshened grasp of physics, his fuller conception of the inorganic world, as indeed thrilling with "the promise and potency of life", will redouble his former energies of work and thought. Thus he will be in a position to winnow the old knowledge with finer sieves, to re-search it with new enthusiasm and subtler instruments. And thus with thought and toil and time he may hope to bring fresher views into the old problems. His handling of these will be at once more vital and more kinetic, more comprehensive and unified.

The further and fuller investigation of the many and ever-opening problems of the nascent science which includes both Life and Non-Life are among the main purposes of the Institute I am opening to-day; in these fields I am already fortunate in having a devoted band of disciples, whom I have been training for the last ten years.

The advance of science is the principal object of this Institute and also the diffusion of knowledge. We are here in the largest of all the many chambers of this House of Knowledge—its Lecture Room. In adding this large auditorium, I have sought permanently to associate the advancement of knowledge with the widest possible civic and public diffusion of it; and this without any academic limitations, henceforth to all races and languages, to hoth men and women alike, and for all time coming.

The lectures given here will announce, to an audience of some ﬁfteen hundred people, the new discoveries made here, which will be demonstrated for the first time before the public. We shall thus maintain continuously the highest aim of a great seat of learning by taking an active part in the advancement and diffusion of knowledge. Through the regular publication of the Transactions of the Institute, these Indian contributions will reach the whole world. The discoveries made will thus become public property. No patents will ever be taken. The spirit of our national culture demands that we should for ever be free from the desecration of utilizing knowledge for personal gain.

It is my further wish, that as far as the limited accommodation would permit, the facilities of this Institute should be available to workers from all countries. In this I am attempting to carry out the traditions of my country, which, so far back as twenty-five centuries ago, welcomed all scholars from different parts of the world, within the precincts of its ancient seats of learning, at Nalanda and at Taxilla.

THE SURGE OF LIFE.

With this widened outlook, we shall not only maintain the highest traditions of the past but also serve the world in nobler ways. We shall be at one with it in feeling the common surgings of life, the common love for the good, the true, and the beautiful. In this Institute, this Study and Garden of Life, the claim of Art has not been forgotten, for the artist has been working with us, from foundation to pinnacle and from floor to ceiling of this very Hall. And beyond that arch, the Laboratory merges imperceptibly into the Garden, which is the true laboratory for the study of Life. There the creepers, the plants and the trees are played upon by their natural environments—sunlight and wind, and the chill at midnight under the vault of starry space. There are other surroundings also, where they will be subjected to chromatic action of different lights, to invisible rays, to electrically charged atmosphere. Everywhere they will transcribe in their own script the history of their experience. From his lofty point of observation, sheltered by the trees, the student will watch this panorama of life. Isolated from all distractions, he will learn to attune himself with Nature; the obscuring veil will be lifted and he will gradually come to see how community throughout the great ocean of life outweighs apparent dissimilarity. Out of discord he will realize the great harmony.

THE OUTLOOK.

These are the dreams that wove a network round my wakeful life for many years past. The outlook is endless, for the goal is at infinity. The realization cannot be through one life or one fortune, but through the co-operation of many lives and many fortunes. The possibility of a fuller expansion will depend on very large endowments. But a beginning must be made, and this is the genesis of the foundation of this Institute. I came with nothing and shall return as I came; if something is accomplished in the interval, that would indeed be a privilege. What I have I will offer, and one who had shared with me the struggles and hardships that had to be faced, has wished to bequeath all that is hers for the same object. In all my struggling elforts I have not been altogether solitary; while the world doubted, there had been a few, now in the City of Silence, who never wavered in their trust.

INDIA’S SPECIAL APTITUDES IN CONTRIBUTION TO SCIENCE.

The excessive specialization in modern science has led to the danger of losing sight of the fundamental fact that there can be but one truth, one science, which includes all the branches of knowledge. How chaotic appear the happenings in Nature! Is Nature a Cosmos, in which the human mind is some day to realize the uniform march of sequence, order and law? India through her habit of mind is peculiarly fitted to realize the idea of unity, and to see in the phenomenal world an orderly universe. This trend of thought led me unconsciously to the dividing frontiers of different sciences and shaped the course of my work in its constant alternations between the theoretical and the practical, from the investigation of the inorganic world to that of organized life and its multifarious activities of growth, of movement, and even of sensation. On looking over a hundred different lines of investigations carried on during the last twenty-three years, I now discover in them a natural sequence. The study of electric waves led to the devising of methods for the production of exceedingly short electric waves which served as a bridge over the gulf between visible and invisible lights; from this followed accurate investigation on the optical properties of invisible waves, the determination of the refractive powers of various opaque substances, the discovery of effect of air film on total reflection, and the polarizing properties of strained rocks and of electric tourmalines. The invention of a new type of self-recovering electric receiver made of galena was the fore-runner of crystal detectors. In physical chemistry the detection of molecular change in matter under electric stimulation led to a new theory of photographic action. The theory of stereo-chemistry found strong support by the production of two kinds of artificial molecules, which, like the two kinds of sugar, rotated the polarized electric wave either to the right or to the left. Again the 'fatigue' of my receivers led to the discovery of sensitiveness inherent in matter as shown by its electric response. It was next possible to study this response in its modification under changing environment, of which its exaltation under stimulants and its abolition under poisons are among the most astonishing outward manifestations. And as a single example of the many applications of this fruitful discovery, the characteristics of an artificial retina gave a clue to the unexpected discovery of "binocular alternation of vision" in man:—each eye thus supplements its fellow by turns, instead of acting as a continuously yoked pair, as hitherto believed.

PLANT LIFE AND ANIMAL LIFE.

In natural sequence to the investigation of the response in "inorganic" matter, has followed a prolonged study of the activities of plant life as compared with the corresponding functioning of animal life. But since plants for the most part seem motionless and passive, and are indeed limited in their range of movement, special apparatus of extreme delicacy had to be invented, which should magnify the tremor of excitation and also measure the perception period of a plant to a thousandth part of a second. Ultra-microscopic movements were measured and recorded, the length measured being often smaller than a fraction of a single wave-length of light. The secret of plant life was thus for the first time revealed by the autographs of the plant itself. This evidence of the plant’s own script removed the prevailing error which divided the vegetable world into sensitive and insensitive. The remarkable performance of the ‘Praying’ Palm Tree of Faridpur, which bows, as if to prostrate itself, every evening, is only one of the latest instances which show that the supposed insensibility of plants and still more of rigid trees is to be ascribed to wrong theory and defective observation. Investigations which I have carried out show that all plants, even the trees, are fully alive to changes of environment; they respond visibly to all stimuli, even to the slight fluctuations of light caused by a drifting cloud. This series of investigations has completely established the fundamental identity of life reactions in plant and animal, as seen in a similar periodic insensibility in both, corresponding to what we call sleep; as seen in the death-spasm, which takes place in the plant as in the animal. This unity in organic life is also exhibited in that spontaneous pulsation which in the animal is heart-beat; it appears in the identical effects of stimulants, anaesthetics and of poisons in vegetable and animal tissues. This physiological identity in the effect of drugs is regarded by leading physicians as of great significance in the scientific advance of medicine; since here we have a means of testing the effect of drugs under conditions far simpler than those presented by the patient, far subtler too, as well as more humane than those of experiments on animals.

Growth of plants and its variations under different treatment is instantly recorded by my Crescograph. Authorities expect that this method of investigation will advance practical agriculture; since for the first time we are able to analyse and study separately the conditions which modify the rate of growth. Experiments, which would have taken months and their results vitiated by unknown changes, can now be carried out in a few minutes.

Returning to pure science, no phenomena in plant life are so extremely varied or have yet been more incapable of generalization than the "tropic" movements, such as the twining of tendrils, the heliotropic movements of some towards and of others away from light, and the opposite geotropic movements of the root and shoot, in the direction of gravitation or away from it. My latest investigations have led to the establishment of a single fundamental reaction which underlies all these effects so extremely diverse.

Finally, I may say a word of that other new and unexpected chapter which is opening out from my demonstration of nervous impulse in plants. The speed with which the nervous impulse courses through the plant has been determined; its nervous excitability and the variation of that excitability have likewise been measured. The nervous impulse in plant and in man is found exalted or inhibited under identical conditions.

A question long perplexing physiologists and psychologists alike is that concerned with the great mystery that underlies memory. But now through certain experiments I have carried out, it is possible to trace "memory impressions" backwards even in inorganic matter, such latent impressions being capable of subsequent revival. Again the tone of our sensation is determined by the intensity of nervous excitation that reaches the central perceiving organ. It would be possible to change the tone or quality of our sensation, if means could be discovered by which the nervous impulse would become modified during transit. Investigation on nervous impulse in plants has led to the discovery of a controlling method, which was found equally effective in regard to the nervous impulse in animals.

Thus the lines of physics, of physiology, and of psychology converge and meet. And here will assemble those who would seek oneness amidst the manifold. Here it is that the genius of India should find its true blossoming.

The thrill in matter, the throb of life, the pulse of growth, the impulse coursing through the nerve and the resulting sensations, how diverse are these and yet how unified! How strange it is that the tremor of excitation in nervous matter should not merely be transmitted but transmuted and reflected like the image on a mirror, from a different plane of life, in sensation and in affection, in thought and in emotion! Of these which is more real, the material body or the image which is independent of it? Which of these is undecaying, and which of these is beyond the reach of death?

It was a woman in the Vedic times, who, when asked to take her choice of the wealth that would be hers for the asking, inquired whether that would win for her deathlessness. Many a nation had risen in the past and won the empire of the world. A few buried fragments are all that remain as memorials of the great dynasties that wielded the temporal power. There is, however, another element which finds its incarnation in matter, yet transcends its transmutation and apparent destruction: that is the burning flame born of thought which has been handed down through fleeting generations.

Not in matter, but in thought, not in possessions or even in attainments, but in ideals, are to be found the seed of immortality. Not through material acquisition but in generous diffusion of ideas and ideals can the true empire of humanity be established. Thus to Asoka to whom belonged this vast empire, bounded by the inviolate seas, after he had tried to ransom the world by giving away to the utmost, there came a time when he had nothing more to give, except one-half of an Amlaki fruit. This was his last possession, and his anguished cry was that since he had nothing more to give, let the half of the Amlaki be accepted as his final gift.

Asoka's emblem of the Amlaki will be seen on the cornices of the Institute, and towering above all is the symbol of the thunderbolt. It was the Rishi Dadhichi, the pure and blameless, who offered his life that the divine weapon, the thunderbolt, might be fashioned out of his bones to smite evil and exalt righteousness. It is but half of the Amlaki that we can offer now. But the past shall be re-born in a yet nobler future. We stand here to-day and resume work to-morrow, so that, by the efforts of our lives and our unshaken faith in the future we may all help to build the greater India yet to be.

CONTENTS

‒‒‒‒

PART I.

RESPONSE OF PLANT ORGANS.

page

 Complexity of the problem—Effects of the 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

 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
 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

 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

 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
 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

 Method of conductivity-balance—Control of transmitted excitation in Averhhoa 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 of Heterodromous and Homodromous currents—Laws of variation of nervous conduction under electric current•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 107

 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

 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.

 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

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

 Effect of stimulants—Effect of anæsthetics—Action of different gases—Action of poisons•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 183

 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
 Effect of intensity—Effect of continuous stimulation—Continuity between 'incipient' and actual contraction—Immediate effect and after-effect•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 195

 Effect of mechanical irritation—Effect of wound•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 200

 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

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

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

 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

 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 of variation of electric resistance•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 239

ILLUSTRATIONS.

figure.
page.

 1 Photographs of morning and evening positions of the 'Praying Palm'•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 6
 2 The Recording Apparatus•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 8
 3 Record of diurnal movement of the 'Praying Palm'•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 10
 4 ,, ⁠ ,, ⁠ Sijbaria Palm•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 12
 5 Curve of variation of moto—excitability in Mimosa pudica•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 16
 6 Effect of physiological depression on diurnal movement of Arenga saccharifera•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 20
 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•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 34
 11 Response of a hooked tendril of Passiflora•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 35
 12 Response of pulvinus of Mimosa pudica•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 36
 13 ,, ⁠ ,, ⁠ Mimosa to variations of turgor•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 39
 14 Diagram of complete apparatus for record of diurnal variation•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 45
 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•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 57
 22 Effect of temperature above the optimum•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 58
 23 Twenty-four hours' record of excitability of Mimosa•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 60
 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•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 67
 29 Diurnal variation of excitability of a summer specimen•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 70
 30 The Resonant Recorder•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 77
 31 Variation of excitability after section•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 81
 32 Effect of amputation of upper half of pulvinus of Mimosa•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 84
 33 Response of Mimosa after amputation of lower half of pulvinus•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 85
 34 Effect of weight on rapidity of fall•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 87
 35 Stimulating action of Hydrogen peroxide•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 88
 36 Incomplete recovery under the action of BaCl2 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 sub-tonic 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•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 117
 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
 56 The compound Lever•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 154
 57 The crank arrangement for oscillation•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 156
 58 Photograph of the High Magnification Crescograph•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 157
 59 Crescographic record of absolute rate of growth of Kysoor, and of effects of cold and warmth on stationary and moving plates•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 161
 60 Record of physical change•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 165
 61 Records of latent period and time relations of growth response•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 166
 62 Record of a single growth-pulse of Zephyranthes•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 167
 63 Records of growth-rate at different temperatures•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 175
 64 Continuous record of growth, showing temperature minimum•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 178
 65 Continuous record of growth, showing temperature maximum•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • „
 66 The Thermo-Crescent Curve•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 180
 67 Curve showing the relation between growth and temperature•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 181
 68 Effects of H2O2, NH3, and ether on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 184
 69 Effect of CO2 on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 185
 70 Effect of irrigation on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 189
 71 Effect of plasmolysis on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 191
 72 Effect of increasing intensity of electric stimulus on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 196
 73 Effect of continuous electric stimulation on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 197
 74 Immediate and after-effects of friction, and of wound on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 201
 75 Normal retarding effect of light on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 206
 76 Record showing latent period of growth in response to light•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 207
 77 Effect of light of increasing intensities•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 208
 78 Continuous effect of light and of electric stimulus on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 209
 79 Effects of different rays of the spectrum on growth•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 210
 80 Photographic records of positive, diphasic and negative electric responses of petiole of Musa•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 214
 81 Record of growth variation of Crinum under Direct and Indirect stimulus•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 216
 82 Effect of electric stimulus on sub-tonic specimen of wheat seedling•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 221
 83 Acceleration of growth under sub-minimal stimulus of light•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 224
 84 Revival by stimulus of light of autonomous pulsations of Desmodium gyrans at stand-still•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 228
 85 Renewal of growth in the mature style of a flower by the action of stimulus•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 230
 86 Effect of light in diminution of amplitude and reduction of diastolic limit of pulsation of Desmodium•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 236
 87 Antagonistic effect of warmth in reduction of systolic limit•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 237
 88 Contractile response of a growing bud of Crinum•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 241
 89 Response of Mimosa pulvinus to white light•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 245
 90 Response of Mimosa pulvinus to blue light•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 246
 91 Response of Mimosa pulvinus to ultra-violet rays•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 247
 92 Response of Mimosa pulvinus to thermal radiation•          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          •          • 248

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1. Inaugural address in dedication of the Bose Institute, November 30, 1917.