# Researches on Irritability of Plants

WORKS BY THE SAME AUTHOR.
RESPONSE IN THE LIVING AND NON-LIVING.
PLANT RESPONSE: AS A MEANS OF PHYSIOLOGICAL INVESTIGATION.
COMPARATIVE ELECTRO-PHYSIOLOGY: A PHYSICO-PHYSIOLOGICAL STUDY.
LONGMANS, GREEN, AND CO. London, New York, Bombay, and Calcutta
RESEARCHES ON IRRITABILITY OF PLANTS
BY JAGADIS CHUNDER BOSE, M.A. D.Sc. C.S.I. PROFESSOR, PRESIDENCY COLLEGE, CALCUTTA
WITH ILLUSTRATIONS
LONGMANS, GREEN, AND CO. 39 PATERNOSTER ROW, LONDON NEW YORK, BOMBAY, AND CALCUTTA 1913
dedicated to s. m.
PREFACE
I have in this work dealing with my researches on the irritability of plants introduced new methods by which the scope of investigation has been enlarged, and a very high degree of accuracy secured. In my previous treatise on Plant Response, the response recorder employed was a modification of the optical lever, automatic records being secured by the very inconvenient and tedious process of photography. The delay thus imposed retarded seriously the progress of the research. Those practically engaged in investigations on plants can realise the difficulties that arise from the too quick passage of the seasons. It thus frequently happened that by the time new instrumental appliances were rendered practicable the favourable season for the plant was over, involving the postponement of the experiment for another year. In spite of these difficulties, the long series of investigations that I then carried out gave many interesting results, which not only threw light on many obscure problems, but also led to the discovery of several important phenomena in plant physiology.
Some of these results, moreover, tended to cast doubt on certain conclusions that had found universal acceptance. It has, for example, been held that there was no transmission of true excitation in Mimosa, the propagated impulse being regarded as merely hydro-mechanical. The question whether the transmitted impulse was physical or physiological could only be satisfactorily decided if the plant could itself be made to record the velocity of its impulse and the changes induced in that velocity under physiological variations. This is but one out of several ​ideal methods of attacking problems in the life of plants, the realisation of which would make a great advance in physiological investigation.
It would also be desirable to discard, if possible, the troublesome method of obtaining record by photography, which necessitates work in a dark room; in this connection it should be remembered that subjection of the plant to darkness introduces complications by modifying its normal excitability. For these reasons, another requirement which it is necessary to fulfil is the devising of some simple and direct method of obtaining the record. And in order that the results obtained should not be influenced by any personal factor, it would be further desirable that the plant attached to the recording apparatus should be automatically excited by stimulus absolutely constant, should make its own responsive record, going through its own period of recovery, and embarking on the same cycle over again without assistance at any point on the part of the observer.
The difficulties encountered in realising these ideal requirements appeared at first to be insurmountable. In the records of response serious errors occurred as regards amplitude and time-relations, owing to the friction of the writing lever against the recording surface. As an extreme instance of this, in recording the rhythmic movement of the leaflets of Desmodium the very slight friction which the smoked-glass surface offered was enough to stop the pulse-record.
After many attempts, I was at last successful in overcoming all obstacles by the device of the Resonant and Oscillating Recorders. Taking the very difficult test of direct record of the rhythmic movements of Desmodium leaflets, it will be found that the pulsations recorded in this book not only gave accurate measure of the amplitude and period, but also the absolute rate of movement during any phase of their autonomous response. Again, in the matter of accurate measurement of short intervals of time required for the determination of the latent period and velocity of transmission of excitation, I have shown the possibility ​of recording time-intervals as short as a thousandth part of a second. A brief account of this is given in my paper "On an Automatic Method for the Investigation of the Velocity of Transmission of Excitation in Mimosa," read before the Royal Society. It will be recognised immediately in how many directions our power of inquiry has become extended by the elaboration of these new methods and the invention of several types of instrumental appliances described in this work.
In presenting the results of these investigations, it will be noted that the plant has been made to tell its own story, by means of its self-made records. Each experiment has been repeated at least a dozen times, in many cases as often as a hundred times. The results may therefore be accepted as fully attested. The establishment of the unity of responsive reactions in the plant and animal, which is the subject of this work, will be found highly significant, since it is only by the study of the simpler phenomena of irritability in the vegetal organisms that we can ever expect to elucidate the more complex physiological reactions in the animal tissues.
I take this opportunity to thank my research assistants, Messrs. Guruprasanna Das, L.M.S., and Surendra Chandra Das, M.A., for the very efficient help rendered by them in these researches.
J. C. BOSE.
Presidency College, Calcutta, October 1912.
CONTENTS
CHAPTER I
PLANT SCRIPTS
page
CHAPTER II
THE RESONANT RECORDER
CHAPTER III
METHODS OF STIMULATION
CHAPTER IV
TIME-RELATIONS OF THE RESPONSIVE MOVEMENT AND STANDARDISATION OF STIMULUS
CHAPTER V
THE ADDITIVE EFFECT; INFLUENCE OF LOAD, TEMPERATURE, AND INTENSITY OF STIMULUS
CHAPTER VI
VARIOUS TYPES OF RESPONSE
CHAPTER VII
EFFECTS OF DIFFERENT GASES ON EXCITABILITY OF MIMOSA
CHAPTER VIII
DEATH-SPASM IN PLANTS
CHAPTER IX
DETERMINATION OF THE LATENT PERIOD
CHAPTER X
INFLUENCE OF INTENSITY OF STIMULUS, FATIGUE, AND TEMPERATURE ON THE LATENT PERIOD
CHAPTER XI
VELOCITY OF TRANSMITTED IMPULSE IN PLANTS
CHAPTER XII
EXCITATORY CHARACTER OF TRANSMITTED IMPULSE IN PLANTS
CHAPTER XIII
THE POSITIVE RESPONSE
CHAPTER XIV
POLAR EFFECTS OF ELECTRICAL CURRENT IN EXCITATION OF PLANTS
CHAPTER XV
POLAR EFFECTS OF FEEBLE AND MODERATE CURRENTS ON VARIOUS SENSITIVE PLANTS
CHAPTER XVI
THE CONTRASTED EFFECTS OF ANODE AND KATHODE
CHAPTER XVII
EFFECT OF TEMPERATURE ON POLAR EXCITATION, AND MULTIPLE EXCITATION UNDER CONSTANT CURRENT
CHAPTER XVIII
POLAR EFFECTS UNDER STRONG CURRENTS
CHAPTER XIX
VARIATION OF POLAR REACTION UNDER TISSUE MODIFICATION
CHAPTER XX
MULTIPLE AND AUTOMATIC RESPONSE
CHAPTER XXI
THE AUTOMATIC PULSATIONS OF DESMODIUM GYRANS
CHAPTER XXII
EFFECT OF HYDROSTATIC PRESSURE, LOAD, AND LIGATURE ON THE PULSATION OF DESMODIUM
CHAPTER XXIII
EFFECT OF STIMULUS ON LEAFLET OF DESMODIUM AT STANDSTILL
CHAPTER XXIV
EFFECT OF ELECTRIC STIMULATION ON THE PULSATION OF DESMODIUM GYRANS
CHAPTER XXV
EFFECT OF TEMPERATURE ON RHYTHMIC PULSATION OF DESMODIUM GYRANS
CHAPTER XXVI
EFFECT OF CHEMICAL AGENTS ON THE AUTOMATIC PULSATION OF DESMODIUM GYRANS
CHAPTER XXVII
ILLUSTRATIONS
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