The Motor Mechanism of Plants

A Phystco-Physiological Study. With 406 Illustra¬ tions and Classified List of 321 new Experiments. « 8 vo, 1 6s. ntft. • Ttansac ions of the Bose Research Institute, Calcutta. jVol. I. ,Part£' I. and II. W^th 92 Illustrations. 15s. net. BOSE, M.A., D.Sc., LL.D., F.R.S., C.S.I., C.I.E. By Patrick Gkddes, late Professor of Botany, Uni¬ versity College, Dundee, St. Andrews University, and Professor of Sociology and Civics, University of Bombay. With Portraits and Illustrations. 8vo, ios. net.

This is one more of the series of volumes in which an account of my researches on plant-physiology has, from time to tir Ae, been given. The present volume deals more particularly with the investigation of the motor mechanism of the plant as compared and contrasted with that of the animal. My investigations in this direction date from the dis¬ covery announced in a Friday Evening Discourse before the Royal Institution in May 1901, that every plant and each organ of every piant respond to stimulation, die excitation Ipeing manifested by an electric lesponse of galvanometric negativitv. The method of experimentation and the results are given in detail in my work ‘ Response in the Living and Non-Living ' (1902). Beginning with ' sensitive ’ plants, I also succeeded in demonstrating that not only these, but ordinary plants as well, respond to stimulation by a mechanical movement, the response being recorded By automatic instruments of high sensitivity (‘Plant Response/ 1906). In my ‘Comparative Electro- Physiology ’ (1907) I employed the method of electric response in order to confirm and extend the results which I obtained by the method of mechanical response. Since then a great deal of new material has accumulated, notably within the iast two years. The sensitiveness of the methods of experimentation has been carried a gteat deal further, so that it has been possible to measure, with a fair degree of accuracy, .the responsive contraction of everua single cell. The present volume contains a complete and up-to-date account of ali my important results on the motoT* response of

plants, including 'single and rhultiple response, as well as automatic movement, dealing at the same time with their functional importance in the life of the plank The state of existing knowledge when I commenced my researches in plant-physiology will be best understood from the following extract from a review of my ‘ Comparative Elcctro-Physiolcgy ’ (Nature, March 8, 1908) : There are in Professor Bose’s work a great many very interesting observations and ingenious methods of experimentati jn which will repay the readers’ attention. In particular, his experiments on root- pressure ?md the rise oi sap . those by which he seek to demonstrate that not onb sensitive plants but all plants respond to excitation by variation in turgescence and electrical state ; his comparison of the glandular structure of Sundew and Pitcher-plants with animal glands; in his demonstration on the motile leaflets of Biophytum of anodic and kathodic effects of the constant current, and the velocity of excitation of excitatory waves. In fact, the whole book abounds in interesting matter skilfully woven together, and would be re¬ commended as of great value, if it did not continually r-.c^use our

This incredulity was but natural since my results CDnt ra¬ diated the theoretical views generally held in regard to the reactions of plant-tissues, which were considered to be very different from those of animal tissues. It has even been thought, in certain quarters, that my interpreiationo of various phenomena observed in the course of my investi¬ gations are opposed to recognised principles of' plant- physiology. In science, which is always progressive, there cannot be any dogmatic principle constituting an unalter¬ able standard of orthodoxy. It may be claimed that ray interpretations are wholly in accord with the principles of physiology in general, the tendency of which is towards the recognition of the essential similarity oi the vital processes in animal and plant, •

The advance of animal physiology has, in a great measure, been due to the sensitive methods that have been employed in its investigations. In plant-physiology, no such methods had been available on account of the great difficulty of securing accurate record of responsive reactions which are relatively ffiebie. The very sensitive instruments that I have been able to perfect have, however, effectively removed all such difficulties, and have made it possible to solve various outstanding problems in plant-physiology by the accurate methods that have been devised.

I have taken the opportunity in this volume to give a more detailed account of the rhythmic peristaltic activity by which the sap is propelled in the plant. Experiments carried out on the animal have also been described, and a general law established in regard to the propagation of tre peristaltic and antiperistaltic waves in both animals and plants. The new results were so revolutionary in their implications and in their effect upon older theories regarding the function¬ ing of piant-life, that there was a controversy in The Times in the spring of 1920 as to the reliability of the indications given h} my extraordinary high-magnification instrumerts in recording the automatic pulsations of the plant and its movements in response to external stimulation. An inquiry was, therefore, undertaken by a committee of Fellows of the Royal Society , including Sir William Bragg and the late Sir William Bayiiss. The members of the committee reporied in The Times of Maj' 4, 1920, that they were satisfied that the growth of the plant and its response to stimulation were correctly recorded by my instrument at a magnification of one to ten million times. The successful working of my instruments has on many occasions been exhibited at various scientific centres in Europe, in the United States, and in Japan. In the Physiological Institute of the Vienna University Prof. Molisch, by the employment of my Automatic Cell-Sphygmograph and Optical Sphygmo- graph, lias recently been able fully to confirm my results {Nature, August 4, 1928). There can, therefore, be no mis¬ giving about the correctness of fact described in this and in other volumes of the series.

that the study of life in the sampler plant -organisation may lead to the solution of many perplexing problems in the physiology of highly complex animal. This will be in case it can c be , shown that the fundamental physiological mechanism of the plant is identical with that of the animal. It was my good fortune* to foresee and demonstrate this so far back as twenty-t'fro years ago. In the preface to my ‘ Plant Response ’ (1906), I wrote : There is .no physiological response given by the most highly organised animal tissue that is not also to be met with in the plant. This was proved in ^detail in the case of identical polar effects induced in Both by electrical currents ; in the conduction of the excitatory impulse to a distance; in the possibility of detecting the excitatory wave in transit and measuring'hs rate ; and in the appro¬ priate rnodification of its velocity by different agencies, even in the case of ordinary plants; in the pafsing of multiple into autonomous response tn ve^ptable tissue^; in the light thrown® by this pheno¬ menon on the causes of fhythmicity ki animal* tissues , in the similar effects of drugs on animal and vegetable tissues. This' Identity of jeffects. indeed, as between the responses of plant and animal, is so deep and so extended, that it is to be anticipated that as several of the obscure problems of animal physiology have already found eluci¬ dation by means of these researches carried 6ut on plants, so others will be found capable of explanation by similar means in the near

This hope has been fulfilled beyond all expectation, will be seen how the results obtained With plants cast a flood of fight on the obscurities of animal response and vice versa. Moreover, the highly sensitive methods employed with plants will be, in fact have already been found to be, of great service m researches on animals. • I would like to take this opportunity of acknowledging the mbst efficient help which I* have received from the research assistants and scholars of my Institute in these prolonged investigations.

Contractility of protoplasm — Motile organ of plants — Automatic movement of growth — Movement in response to stimulation — Conduction of excitation- -Automatic pulsation Mechanical, chemical, thermal, photic, and electric modes of stimu¬ lation —Similar reactions under diverse stimuli — Contrivances for accentuation of external stimulus — Quantitative stimulation bv electro-thermic method and by induction-shock — High sensitivity of Mimosa — Direct and transmitted excitation — The Response Recorder — Elimination of error arising front friction — The Optical Lever — The method of intermittent contact in record — Tito Tapping Recorder — The Electro-Magnetic Phytograph — Phvtogram its own chronogram — The Resonant Recoider — The Electro-Oscillating ^Recorder — The Clockwork Oscillator — Characteristic responses of Mimosa, Biophytum, Neptunia, and Erythrina ...... $ . .

Feeble contractility of upper half of pulvinus — Quantitative demon¬ stration of i.nequal pliability of the organ — Movement of fall wf leaf due not to flaccidity, but to active contraction — Record of response in normal and in inverted position — Effect of the weight of the leaf — The reaction of the upper half of the pulvinus — Comparison of excitabilities of the two halves in intact plant — Characteristic responses of highly ekcitablr and of subtonic pulvinus — Dependence of amplitude of response on the number of the excited ceils — FJastening of recovery under enhanced rate of ascent of sap — 1'he rate of work

Determin ction of the latent period— Additive effect of Stimulation- Uniform response — Enfeeblement of response under fatigue— Fatig le — Reversal under continuous stimulation — Dissipation of energy in response — EfEct of environmental, stimuli in modify¬ ing the tonicity of the plant — Tonicity above and below par— Erectile response of subtonic specimens indicative of increase of potential energy of plant — A and I' reactions — Transformation from positive to negative response after successive stimulations Staircase response — Cyclic variation under stimulation — theory of assimilation and dissimilation ......

Active, semi-active, and inactive pulvinus — Anatomy of the pulvinus of Mimosa — Detection of ‘ active substance ' in the* contractile tissue of Mimosa — Localisation of contractile sells by staining- — Stained cells sparsely distributed in semi-active pulvinus— Absence of staining in inactive pulvinus — Staining of dihtront pulvinv of the same plant — The scale of excitability cf pulvini parallel to distribution of stained cells — Granular character of active plasma in rapidly contractile cells — Active and relatively inactive animal muscle — Micro-chemical tests of active substance in the pulvinus . . . . . * •

Effect of variation of light on excitability of Mimosa — Inhibition of power of contraction by excessive absorption of water — Effect of variation of temperature — Stimulating action of Ozone — Asphyxiation produced by Carbonic Acid Gas — Poisonous effect of Sulphuretted Hydrogen — Effect of Ether in depressing excitability , — Action of stronger narcotics ....*• Experimental -advantages of cut specimens — Moto-excitability and conductivity — Transmission of exci cation through immotile pulvinus — Effect of age on conductivity and excitability —

Effect of wound in modifying excitabilicy — Quanta ative deter- mination of rate of aecay 'of excitability after section— Action of light and darkness on moto-excitability — Action of Barium chloride — Antagonistic action of acid and alkali . . • 7^ The ‘ sleep ’ of plants — Determination of periodic variation of excitability — Automatic recorder for twenty-four hours — Uni¬ form periodic stimulation — Effect of external variations on excitability— Effect of diurnal variation -jf light — Effects of moderate and excessive lowering of temperature— Effect of variation of temperature above optimum — Record of diurnal variation of excitability of a spring specimen — Uniform excit¬ ability between noon and 3 p.m. — Gradual increase of excitability between 8 a.m. and noon — Relation between hour of the day, temperature, and excitability — Variation of turgor — Effect of physiological inertia — Effect M season — Diurnal variation of moto-excitability of summer-specimen - Nycti tropic increment as affecting the record . . , . • . . « .

The Monopolar Method —Effect of feeble current in excitation — Effect of moderate current — Bipolar Method of excitatory re¬ action — Laws of Polar Excitation of Feeble and Moderate Currents — Effects of stronger currents — Polar reaction of Type III — Polar reaction of Type IV — Polar reaction of leaflets of various sensitive plants — -Supplementary Laws of Polar Excitation of Strong Currents — Complications arising from presence of secondary poles — Occurrence of polar react" Dn of Type III and Type IV even in complete absence of secondary ^oles — Polar excitation of ordinary plants . . . . .106

The isolated pulvinar preparation— The pulvinar response — Restora¬ tion of normal irritability after recovery from shock of operation — Stimulating action of dilute solution of camphor on Contractile responses of pulvinus of Mimosa and of muscle cf Prog — Stimu¬ lating action of Caffein and of Musk on pulvinar 1 espouse _ Stimulating action of minute dose of Strychnine on pulvinus of Mimosa and on muscle of Frog .... Tofal number of active cells in pulvinus of Mimosa — Contraction under moderate stimulation coniined to lower half of pulvinus — Measurement b> Method of Diametric Contraction — The Auto¬ matic Cell-Sphygmograph- —Cellular contraction under stimulation — Measurement of a contractile cell of the pulvinus, and of the amount of its con fraction — Diametric contraction of cortical cells in the stem — Continuity of contractile response in cortical cells of

Diametric contraction of ordinary stem under stimulation — Experi¬ ments witji the Optical Sphygmograpli — Comparison of sensitivity of ordinary plants and of human subjects — Latent period a* ordinary cortex — Modifying effect of tonic condition on the sign of response — I >eath-spasm under intense electric stimulation — Re¬ sponse ot ordinary leaves to direct and indirect stimulation — Measurement of'differential excitability of an anisotropic organ — Differential excitability of pulvinus o.i Mimosa and of leaf joint >f ordinary plant — Differential excitability cf petiole — ’on- tractile response of radial organs — Respanse of the stem by bending uflder unilateral stimulation — Induction of physiological anisotropy in radufi organs — Neutralisation of anisotropy — The cellular mechanism — Response of leaf of Mimosa to supply or loss of water — Response of ordinary leaf — Cellular contraction and expansion under loss or accession of water -Cellular con-

Electric response of Miruosa pudica — The experimental method — -Electric resp : nse to transmitted excitation — Persistence of electric response when leaf is restrained from movement — Electric response of ordinary plants— -Torsional stimulation — Additive effect of stimulation — Apparatus and plant-chamber — « Effect of increasing intensity of stimulation — Uniform responses -—Fatigue — Effect of temperature — Effects of anaesthetics and poisons .

The photo-electric cell — Response of the Teaf to light--Effect of , . increasing quantity di light — Unmasking of the A-effect on sudden stoppage of light — Phenomenon of ' overshooting after neutralisation — Positive electric response of Hydrilla — A- and ,>• effects. . • • • • • • 9 • • • ^ Variation of resistance under mechanical stimulation — Uniform responses of diminution of resistance — Effect of chloroform — Response to electric stimulation of moderate intensity- — Response of subtonic tissue to feeble stimulation — Multiple response under strong stimulation — Quadrant Method for response to stimulus of light — Uniform responses — Response to light from a single spark — Effect of increasing intensity of light — Effect of anaesthetics — Death-response at fatal temperature — Positive and negative reactions . . . « - • * • • .'28

Thermo-mechanical curve of death — Record after deu<th — Lowering of death-point by fatigue? — Post-mortem relaxation — Death- excita ion in all plants— TJiermo-mechamcal record of ordinary pulviuus and puivinoid— Death-response of anisotropic growing organ — Death-excitation of radial organs — Electric elt citation at death a . . . . . . ... . &oo Transmitted death-excitation of Mimosa — Transmission of death- excitation in Averrhoa- — Death-excitation under action of poison — Transmission of excitation and translocation of poison . . 212

The Recording Balance — Death- record of fruit by variation in weight — Death-record of stem, ol petiole, and of root — Record of living tissue bala nced by dead — The fundamental physiological reaction 219 Pulsating leaflet of Desmcdi um gyyans — The necord of pulsation by Oscillating Recorder — Periods of systolic contraction and diastolic expansion— Previous storage of energy necessary for pulsation — Revival of puisation by external stimulation — Per¬ sistence of revived activity dependent on energy previously absorbed — MuKaple response, a Jink between ordinary response and automatic movement — Multiple response under strong •indirect stimulation, electric, thermal, and .chemical — Detection of multiple electric response in all tissues — Multiple response under direct stimulation — Response on * all or none ’ principle — Effect of increasing intensity of stimulation — The refractory period — Cau^e of rhythmicity — Semi-automatism

Advantages of the Resonant Cardiograph for accurate record of time- relations at different phases of pulsation — The experimental method of subjecting sinus to external variations — Neurogenic and myogenic theories of origin of heart-beat — Record of rhythmic activity of isolated pulvinule of Desmodium — Criteria of all rhythmic activities-— Effect of variation of internal pressure on pulsating animal and plant organs — Oxygen necessary for maintenance of pulsation — Asphyxiating action of C02 arrest¬ ing pulsation in plant and animal — Modifying action of tonic condition on response to external stimulation — Inhibitory action of stimulus on vigorous pulsation — Stimulating action on feeble pulsation— -Parallel effects of variation of temperatuie on pul¬ sation of Dermodium and of the 'heart — Effect of chemical agents on cardiac and Desmodium pulsation — Physiological antagonism of drugs ..........

Functional activ ty in the propulsion of nutrient substance — Slow propagation of excitation bv visible cell-to-cell contraction in rhythmic tissue — Evolution of rapidity of conduction in nervous tissue — Peristaltic wave in alimentary canal — The Peristal tograph — Characteristics of peristaltic pulsation — Effect of deprivation of oxygen arresting peristalsis — Asphyxiation by COa — Effect of variation of temperature on frequency of pulsation of the stomach — Effects of strong and feeble electric stimulation in revival of activity — Effect of chemical stimulation — Peri¬ stalsis and antiperistalsis — Peristaltic wave in the heart — Direction of propagation determined by differential activity at two ends of the organ — Reversal of normal wave — Peristaltic wave in the stomach — Effect of stimulation on stomach at standstill — Peristaltic transmission "relatively more effective than antiperistaltic — Effect of continuous stimulation — Law of pro¬ pagation of peristaltic wave . . . . .

Effect of poison in arresting ascent — Simultaneous reaction of poison on suction and on responsive fall of leaf — Method of Erectile Re¬ sponse — Effect of stimulation in reviving the propulsive activity in subtonic. shoot — Effect of variation of temperature on rate of ascent — Effect of alternate application -of chemical depressant and stimulant — Irreversible action of poison .... 293 Uniform sphygmograms — Effect of change of temperature — Effect of variation of the transpiration-current — Simultaneous tphygmo- grain and phytogram — Transport of sap in normal and in reversed directions — Intensity cf transmitted impulse in the two direc¬ tions — Periodic variation of sap-pressure — Diurnal variation of sap in leafy trees — Diurnal variation in leafless trees . . . 30S

Electric pulsation of pulvinule of Desmodium — Automatic mechanical pulsation of pulvinule of Desmodium attended by corresponding automatic electric pulsation — Persistence of electric pulsation even after physical restraint of mechanical rmisation — Localisation of the pulsating propulsive layer by the Electric Probe — Record of the electric pulsation iu the active cortex — Effect of diminished and increased internal pressure on rnechai ical pulsation of Desmodium leaflet, on the electric pulsation of the propulsive layer, and on the rate of ascent of sap— Effect of variation of temperature — Effect of subtonic condition — Peristaltic wave in unidirectioned propulsion of sap . 325

The Potograph for recording rate of suction — Root not essential for ascent of gap — Transport of sap in absence' of root and leaf — Role of transpiration in the unidirectioned propulsion of sap _ Active ascent in absence of root-pressure and of transpiration _ Movement of sap in downward direction. — Effectiveness of \rans- poit: in normal direction greater than in reverse direction — Unequal transport in two directions across cell-wall which acts as a valve pieventing in a measure the backward flow

Effect of irrgation fff the two ends of a bare stem — The residual flow Effect of thermal stimulation of upper encl in inducing movement of sap — Effect of depression of upper end by cold — Effects of stimulation and depression of lower end — Combined effects — Comparison of rate of ascent in intact plant and in ' a bare stem — The Bubble- method — Effect of enhanced activity of basal end and of depressed activity of apical end — Law of directive flow of sap ........ 348

The Optical Sphygmograpb — Effect of pressure at contact on record of sap-pressure — Optical demonstration — Mechanical record of propulsive pulsation — Method of the Magnetic Sphygmograph — Characteristics of pulsation during fall and rise of pressure — Effect of application of heat at cut end of Shoot — Effect of ligature on pulsation — Effect of direct stimulation on nalse arrested by ligature — Effect of indirect stimulation . . .359 Identical action of alkaloids and other drugs on propulsion of sap and on circulation of blood — Effect of dilute Camphor an heart¬ beat of Frog — Effect of Camphor in enhancing sap-pressure by increasing pumping activity — Effect of depressants on heart¬ beat of animal and on pumping activity in plant — Antagonistic reactions of Musk a"d KBr on heart beat — Antagonistic re¬ actions of Musk and KBr on sap-pressure — Action of Atropine and Morphine on animal heart — Parallel action on propulsive activity in plant — Opposite action of minute and large dose of Strychnine onfcpulsation of animal and plant — Action of Cobra- venom .......... 372

Increase of sap-pressure in the stem at sphygmographic contact on application' of heat above if — -Decrease of sap-pressure on application of cold — Erectile respotfs^ of leaf by application of heat above — Responsive fall of leaf bn application of cold — Experiments with bale and sealed stenis — Detection of sap- movement by Sphygmograpli — Sap-movement and variation of pressure induced in sealed stem by stimulation — Effect of electric stimulation below contact — Effect of electric stimulation above contact —Effect of simultaneous stimulation below and above — Peristaltic and antiperistaltic waves in stomach and in stem — Effect of chemical stimulant and depressant — Effect of alternate application of stimulant and depressant— Movement of sap transporting chemical substances in leafless trees in spring — Effect of thermal stimulation applied below and above contact — Physiological character of response to stimulation bymoveme nt of sap — E ffect of thermal depression — 1 nteraction between distant organs — The hydraulic and nervous means of communication — The plant an organised unity . . . . •

Complete apparatus for automatic record of response of Mimosa . . . . . • . . . * . . Diagrammatic "epresentation 01 the Electro-Oscillating Recorder ......... Effect of local stimulation of upper half of pulvinus of Mimosa by light ........ Method of measurement of up or down angular displacement under equal weights ....... Curve0 showing angular displacement under increasing weights which pulled the leaf upwards and downwards Response of Mimosa in normal positi m and inverted position Effect or weight on rapidity of fall of leaf . . . .