The Modern Review/Volume 38/Number 6/The Unvoiced Life

by Jagadish Chandra Bose

 

THE UNVOICED LIFE

By Sir J. C. BOSE, f.r.s.

The mysterious workings of life continually baffle the inquirer, for numerous are the difficulties which confront him. The generally accepted view is that the mechanism of life is widely different in the animal and in the plant. The animal responds to a shock by a rapid twitching movement; ordinary plants are regarded as insensitive to a succession of blows. The animal has a pulsating heart, the plant being supposed to possess no such throbbing organ. The sense organs of the animal, like so many antennae, pick up messages of external happenings, the tremor of excitation being conducted along nerves to produce reflex movements at a distance. All authorities are unanimous in their belief that the plant possesses no nervous system. Two streams of life are thus supposed to flow side by side with nothing common between them. This view is wholly incorrect and it is the paralyzing influence of wrong theories that has arrested the march of knowledge.

It may be admitted at once that there are reasons for the prevailing error, for, to all outward appearances, the plant seems to be immobile and insensitive. Yet the same environment, which with its changing influences so profoundly affects the animal, is also playing upon the plant. Storm and sunshine, the warmth of summer, and the frost of winter, drought and rain—all these and many more come and go about it. What subtle impress do they leave behind? Internal changes there must be; but our eyes have not the power to see them. For, detecting the invisible internal changes, it became necessary to discover a compulsive force by which the plant was made to give an answering signal; instrumental means had then to be supplied for the automatic conversion of these signals into an intelligible script; and, last of all it was necessary to decipher the nature of the hieroglyphic.

Let us consider the conditions which are necessary for the advancing the frontiers of knowledge. For this three factors are important: a clear inner vision, great experimental dexterity and power of invention of supersensitive instruments by which alone the realm of the invisible could be successfully explored.

India’s Gift

Nothing can be more vulgar or more untrue than the ignorant assertion that the world owes its progress of knowledge to any particular race. The whole world is inter-dependent, and a constant stream of thought has throughout ages enriched the common heritage of mankind. It is the realisation of this mutual dependence that has kept the mighty human fabric bound together and ensured the continuity and permanence of civilization. Although science is neither of the East nor of the West, but international in its universality, yet India by her habit of mind and inherited gifts handed down from generation to generation, is specially fitted to make great contributions in furtherance of knowledge. The burning Indian imagination which can extort new order out of a mass of apparently contradictory facts, can also be held in check by the habit of concentration: it is this restraint which confers the power to hold the mind in pursuit of truth in infinite patience. The true laboratory is the mind, where, behind all illusions we catch glimpses of truth. In order to discover the life mechanism in the interior of the tree, one has to become the tree, and feel the throbbings of its beating heart. This inner vision has, however, to be frequently tested by results of experimentation; for, otherwise it may lead to the wildest speculation subversive of all intellectual sanity. It is only by the contact of the hand with real things that the brain receives its stimulating message and the answering impulse then gives the hand its cunning.

For great inventions, a clear inner vision is also essential. When microscopic vision fails, we have still to follow the invisible, for the little that we can see is as nothing compared to the vastness we cannot. For example, exploring the realm of the invisible, the Magnetic Crescograph had to be invented producing the stupendous magnification of a hundred million times.

Such supersensitive apparatus is however of no avail unless one can make use of it after having gained complete control of the adjusting hand. For any imperceptible tremor of the finger becomes enormously magnified by the highly sensitive apparatus. The power of the mind in controlling the body is beyond anything that has been conceived: and the results achieved are even more wonderful than the illusions of magic.

The conditions for any great discovery are, then, a great imaginative faculty and power of introspection, the faculties of invention and of great experimental dexterity. I am in a position to say that the Indian worker has an unique advantage in his introspective power acquired under special training; in experimental dexterity also he can hold his own; I shall presently have occasion to speak of his capacity for invention and constructive skill. All these can be imparted by personal training and through years of discipline.

In founding my Institute eight years ago, I called for my disciples those very few, who would devote their whole life with strengthened character and determined purpose to take part in the infinite struggle to win knowledge for its own sake and see truth face to face. It was not to a life of passivity that they were called, but to one of intense activity; held in check, the power conserved being set free for breaking through all obstacles in extending knowledge for common benefit of mankind. The ideals and methods pursued in my Institute are by no means utopian; their practicality is fully attested by the unusually large number of investigations that have been brought to successful conclusion in the course of the last few years. The account of these investigations, some two hundred in number, will be found fully described in the seven volumes published by Messrs. Longmans and Green^[1].

Inventions

This great productivity is to a great extent due to the successful invention, at the Institute, of instruments of such extraordinary sensitiveness that considerable incredulity was at first entertained about their performance. The exhibition of the instruments at various scientific centres in the West has, however, removed all and it has now been recognised that India’s specific contributions would greatly advance different branches of knowledge. The phenomena of life are ultimately due to the reactions of individual cells, and are therefore infra-perceptible; they cannot be detected on account of the imperfections of our senses. Speculation, often most grotesque, has taken the place of ascertainable facts blocking all advance of knowledge. The new instruments by their automatic records are now for the first time, revealing the inner mechanism of life, and many regions of inquiry have been opened out, which had at one time been regarded as beyond the scope of experimental exploration. Of about fifty new inventions have been perfected, I will mention a few typical ones.

The Magnetic Radiometer. This enables the accurate measurement of energy of every ray in the solar spectrum, and their relative loss by atmospheric absorption, as the sun moves from the horizon to the zenith. In conjunction with a special calorimeter it has enabled the determination of the efficiency of the chlorophyl apparatus of green plants in storage of solar energy. This efficiency has been found to be much higher than had previously been supposed.

The Radiograph. The changing intensity of daylight from hour to hour, and the effect of moisture-laden air in the modification of the intensity, has been automatically recorded by an electric device.

The Resonant Recorder. Records of time, as short as a thousandth part of a second, has been obtained, enabling the most accurate determination of the latent or perception period of the plant, and the velocity of its nervous impulse.

The Conductivity Balance for Nervous Impulse. This new method enables the determination of the effect of various drugs in the enhancement or depression of nervous impulse in plant and in animal.

The Electric Probe. By the invention of this device, it has been possible to localise the nervous tissue in the interior of the plant, as also the pulsating layer of cells by which movement of sap in trees is maintained.

Mechanical Recorder for Plants. A great advance in plant-physiology has been rendered possible by this instrument which records

 

The Bose Institute Mayapuri Research Station at Darjeeling at a height of 7000 feet

 

the response of all plants, sensitive and ordinary, under external and internal stimuli.

Recorder for the Ascent of Sap. No apparatus has hitherto been available for the detection or measurement of the movement of sap in the interior of the plant. The problem has been completely solved by the invention of two independent methods of record, mechanical and electrical.

The Transpirograph measures the rate of transpiration current and has enabled the determination of the water transpired by a single stoma of the leaf.

The Photosynthetic Recorder automatically inscribes, on a moving drum, the rate of carbon-assimilation by plants. It is so extremely sensitive that the formation of carbohydrate as minute as a millionth of a gram can be detected by its means. One of the most important results discovered is the extraordinary increase in the power of assimilation. produced by infinitesimal traces of certain stimulating agents.

The Crescograph was invented to measure instantly, the imperceptible rate of growth, and its induced variations under chemical and electrical stimulants. This device enables the discovery of substances, traces of which are of extraordinary efficacy in increasing the growth of plants on which the food supply of the world depends.

The Magnetic Crescograph enables movements, which are beyond the highest magnifying powers of the microscope, to be detected and recorded; the magnification produced may be carried to a hundred million times. This invention has opened out possibilities for great advance in various branches of science.

 

The Snows facing Mayapuri

 

Paralysis of Scientific Effort

Nothing is so effective in paralysing all efforts as the hypnotic suggestion of incapacity. When I commenced my investigations a third of a century ago, I heard every one saying that experimental skill was wanting in our workers and that the people lacked the power of invention and construction. And it was only after years of persistent efforts that I have been able to prove that there is no difficulty so great as cannot be overcome by the power of will; that when one dedicates oneself wholly for any great object, then the closed doors shall open and the impossible become fully attainable. As regards construction of apparatus by Indian mechanicians, it seemed to me that the race, which by the subtle dexterity of their hands wrought wonders in the past, could not altogether be extinct. It was only necessary for me to take my craftsmen into my confidence and fire them with enthusiasm and to hold before them the marvel to be achieved. All these instruments have been constructed in my workshop; their great perfection and high sensitiveness may be judged from the fact that though they have been widely exhibited in all the scientific centres of

 

The Forest Garden attached to Mayapuri Research Station

 

 

The Bose Institute, Calcutta

 

Europe and America, and though the most renowned instrument makers were allowed to examine and sketch the essential parts of the apparatus, yet they found it impossible to duplicate the instruments. It was frankly admitted that our craftsmen possessed tactile delicacy which could not even be approached. Requests have therefore been made by different Universities that my Laboratory should supply them with duplicates of instruments for the successful pursuit of the intricate researches originated in India. It is necessary to lay special stress on the point at this juncture, when the assertion, totally ignorant and unfounded, is being made that the country is incapable of making any great industrial advance.

History of a Discovery.

The importance of due combination of introspective and experimental methods and the necessity of long persistence in solving the most intricate problems is best illustrated by the efforts which culminated in my present discovery. The problem of the rise of sap in trees has baffled all inquirers for more than two hundred years. How is the water transported from the soil to the top of a tree which in the giant Eucalyptus reaches a height of 450 feet? Is the movement of sap due to physical forces or to some unknown activity characteristic of living cells? In deciding this question Strasburger applied poison and imagined that it did not in any way modify the movement of sap. The rise of sap could not therefore be due to the activity of living cells, a conclusion which found general acceptance. The advance of knowledge has always been blocked by the dictum of authority, and no one ventured to question the conclusion of one so eminent as Strasburger. All the efforts of inquirers were henceforth diverted to the discovery of some physical cause for which the most far-fetched theories have been put forward in reconciling speculation with facts which contradicted it. It took me twenty-two years to demolish the various false assumptions and establish the correct theory. Five series of investigation have been carried out during these years, each of which independently confirmed the new theory. For my first series of investigation undertaken more than twenty years ago, I invented an apparatus for the automatic record of the rate of suction by the plant. I was then able to show that so far from poison having no effect on the movement of sap, it caused a quick and permanent arrest of the ascent, the propulsion of sap being therefore due to the activity of living cells. Though a very definite and conclusive demonstration was given, yet the conservatism of science was so great that it had little effect on those committed to the old theory.

In spite of special pleading, the physical theory was found to be wholly unsatisfactory. The ascent of sap was next supposed to be brought about by the action of two mysterious forces, one of which pushed from below, and the other pulled from above. The push was imagined to be caused by “root-pressure.” In order to show that this was not essential, I cut off the root with the result that the rate of ascent was actually increased. The pull from above was supposed to be entirely due to the transpiration from the leaves. I next cut off all the leaves and coated the bare stem with impermeable varnish, the cut end of the stem being placed in water. The movement of sap still persisted, proving that the active tissue which maintains the movement of sap is not confined to the root or to the leaf, but exists throughout the length of the plant. By stimulating the lower or upper ends of the bare stem, I was able to make the sap ascend or descend at will. As in the movement of blood in some lower animals in which the heart takes the form of an elongated tube, a peristaltic action causes the movement of sap.

There are various physiological agencies which enhance the activity of the animal heart. Do they have similar effect on the plant as evidenced by the increased rate of propulsion of sap? No satisfactory evidence was at first available since no detector was known, which served as a visible indicator of the movement of sap.

The Leaf Indicator.

No one imagined that the leaf was such an indicator. Under drought, it begins to droop; after irrigation it becomes erect. The rate of movement of the rise of the leaf can thus be made to measure the rate of ascent of sap. The leaf-movement is, however, too slight for purposes of exact measurement. This drawback has been entirely removed by my simple device of the Optical Lever. The leaf is attached to one end of the lever by a thread; the fulcrum rod carries a small mirror from which is reflected a beam of

 

The Revealer
The invisible waxing and waning of life revealed by the moving trail of light

 

light thrown on the distant screen. The slightest movement of the leaf up or down, can thus be easily magnified some five thousand times.

Here is a plant from which supply of water has been withheld; the leaf is drooping and the indicating spot of light shows a rapid fall. We will now make its pumping mechanism active by making the plant imbibe water containing ether which, in small doses, is a stimulant. Observe how magical the effect is; the down-movement of the spot of light is reversed into a rapid up-movement. I will now stop the plant’s exuberance by poisoning it with a fatal dose of potassium cyanide. Watch the conflict between life and death. The struggle is now ended, and death has at last claimed its mastery. We try in vain to revive the plant and restore the ascent of sap by irrigation with fresh water. Can there be any evidence more conclusive than this in proof of the activity of living cells in propulsion of sap?

Blood-pressure and Sap-pressure

My results prove that an identical mechanism maintains the circulation of blood in the animal and propulsion of sap in the plant. A necessary consequence of this is that variations of blood-pressure and sap-pressure should be produced under parallel conditions. The most important factor in causing arterial pressure by the circulating fluid is the pumping activity of the heart. Under stimulating agencies this becomes enhanced with resulting increase of blood-pressure; under depressing conditions the pressure becomes decreased. The radial artery on the wrist is exposed and it is easy to feel the pulse-beat or record it by the Sphygmograph. For demonstration before a large audience, a simple contrivance is shown by which the pulse-beat is magnified by a reflected beam of light. The pulse is beating at the rate of about 72 per minute or say once in a second. The frequency of the beat is not always constant but fluctuates under excitation or depression.

The normal blood-pressure and its induced changes can also be recorded by elaborate contrivances. The record thrown on the screen shows the change in the blood pressure by alternate stimulation and partial inhibition of the activity of the heart-pump. Under normal conditions the up and down-strokes of each constituent pulse are equal. During increasing

 

Record of falling and rising blood pressure. Note the relative sizes of up-stroke and down-stroke

 

blood-pressure, the up-stroke is the larger of the two.

The radial artery on the surface offers an unique advantage in obtaining the record of human pulse. But this method fails when an attempt is made to record the throbbings of an artery in the interior, buried under other tissues.

An attempt to feel the pulse of the plant would, by the very nature of the case, appear to be hopeless. If the plant propelled the sap by periodic pulsations of the active cells, the amount of expansion and contraction of each pulse would be beyond even the highest powers of the microscope to detect. The active cells are moreover buried in the interior of the plant; how could the invisible and hidden be rendered visible?

Searching the Heart of the Plant.

Two years ago, I succeeded by means of my Electric Probe, to get access to the smallest unit of life, the ‘life atom’ and record its throbbing pulsation. On making suitable electric connections with a muscle in a state of rest, the galvanometer in circuit remains quiescent. But contraction of the muscle under stimulus causes a sudden deflection of the needle of the galvanometer in a definite direction, the expansive recovery of the muscle being followed by galvanometer deflection in the opposite direction. A single mechanical pulsation of contraction and expansion is thus attended by a corresponding electric pulsation. If electric connection be next made with the heart of the animal, the heart-beat is independently manifested by the corresponding electric pulsation. For localising the heart of the plant, the Electric Probe was gradually introduced across the stem; when the Probe comes in contact with the active cell, it sends out electric signals which are automatically recorded by the Galvanograph. The up-stroke of the records indicates expansion and absorption of sap, while the down-stroke indicates expulsive contraction. It is thus found, that the cells actively engaged in propulsion of sap, are in a state of incessant pulsation, expanding and contracting by turns. Each cell during its phase of expansion absorbs water from below, and expels it upwards during the phase of contraction. The ascent of sap thus takes place by the coordinated activity of a series of vertically situated cellular pumps.

It was however objected that this proof was indirect; what was wanted was a tangible demonstration of the change of sap-pressure by excitation or depression of the cellular pump, and, if possible, to record the constituent pulse itself.

The Plant-Feeler.

Let us follow the course of the sap-stream with clear inner vision. The plant is pumping the sap along the stem; the passage of each pulse

 

The Plant-Feeler and Automatic Recorder of Sap-pressure

 

must therefore be attended by an infinitesimal expansion. After the brief passage of the pulse-wave, the stem would revert to its original diameter, till the next pulse re-inflates it once more. A stimulant would make the heart-pump work more energetically, either by making the length of the stroke larger or the frequency quicker. The sap-pressure would then increase, as would be evidenced by the greater inflation of the stem. Under depressors, the change would be of an opposite character. What was seen by the mind’s eye, now requires experimental verification. For this, it is necessary to construct artificial organs of perception of surpassing delicacy and sensitiveness. The Plant-Feeler or the new type of Sphygmograph consists of two rods, one of which is fixed and the other movable, the stem of the plant being placed between they two. The expansive pulse-wave pushes the movable rod outwards by an infinitesimal amount which has to be magnified at least fifty thousand times by the special device shown. This amplification is sufficient to enlarge the wave-length of sodium light to 25 mm. Great precautions have to be taken to eliminate all mechanical disturbances by the invention of special shock-absorbers. The artificial earthquake produced by the passage of motor-vans is however introducing increasing difficulty in the use of supersensitive instruments. Occasional respite for obtaining satisfactory record is obtained when there is a lull in the traffic I have sometimes been compelled to carry the instruments to my Mayapuri Research Station at Darjeeling, situated at a height of 7000 feet. The Laboratory built on a substratum of solid rock affords sufficient protection against all mechanical disturbance.

The apparatus giving a magnification of fifty thousand times is quite effective in giving an immediate record of effects of stimulants on the active cells, a sudden rise of the curve demonstrating the resulting increase of sap-pressure. Depressing agents, on the other hand, produce a fall of the curve showing a diminution of pressure. The sensitiveness of the apparatus is, however, not sufficiently high to show the individual pulsations; it is therefore necessary to carry the magnifications to five million times in demonstration of the alternate expansion and contraction of the cellular pump in the act of propelling the sap.

The Magnetic Sphygmograph.

The magnetic instrument for producing enormous magnification is shown at work. A beam of light reflected from the mirror attached to the astatic magnetic

 

Record of Mechanical Heart-beat of Plants. Note falling and rising sap-pressure showing constituent heart-beats

 

system is thrown on the screen. When a dead plant is attached to the apparatus, the indicating beam of light remains quiescent, the heart-beat of the “plant having been stilled in death. But the imperceptible heart-beat of the living plant is outwardly manifested by alternate swings of the beam of light. The frequency varies in different plants from fifteen to five beats per minute. A depressing agent causes diminished sap-pressure as seen in the sudden rush of the light beam to the left, the down-stroke of the individual beat being relatively large. A stimulating agent causes, on the other hand, a rush of the beam of light in the opposite direction, the up-stroke being more pronounced than the down-stroke. The unseen waxings and wanings of life are thus, for the first time, revealed by the moving trail of light.

Utility.

I have been often asked: What could be the practical use of these researches on the recondite life-phenomena of plants? A similar question used to be asked when so far back, as 1894, I succeeded in transmitting energy by wireless electric waves for starting machinery at a distance or exploding a distant mine. The invention of the galena receiver in my laboratory also solved the difficulty of long distance transmission. All this was regarded at the time as a mere scientific curiosity.

All the efforts of the Institute are concentrated on the establishment of the great generalisation that all life is one and that an identical mechanism is operative in both animal and plant tissues. This is demonstrated by a similar motile mechanism, and by the discovery of a very highly differentiated nervous system in the plant. It is proved by the throbbing pulsation in the plant which in the animal is the heart-beat; by the violent spasm that occurs in the plant at the supreme crisis of death. Surprising also are the identical effect of drugs, of stimulants and poisons on the two types of life, this being regarded by leading physicians as of great importance in advancing the Science of Medicine. By researches on growth rendered possible by the invention of the High Magnification Crescograph, the Laws of Growth are being established, a knowledge of which is essential for any real advance in Practical Agriculture. Overwhelming are the new results that are being accumulated every day, but we cannot stop to reap the fruit which must be left for others. The stress and burden are to be for those only who have started on the great adventure into the region of the Unknown.

For the economic welfare of a vast continent like India, there must always be the two complementary activities, industry and agriculture. Both depend on applications of science, which is capable of very great advance. I have often tried to draw public attention to the problems of the immediate future and shall do so once more. I have shown that there is a great capacity in Indians for discovery and invention. How is this to be utilised for saving India in her present economic crisis? Let us frankly face the danger; the present unrest in India, as in Europe, is in reality ultimately due to severe economic distress. It is hunger that drives people to desperation and to the destruction of all that has been slowly built up for ordered progress. In other parts of the world, it is not doctrinaires but the best intellect of the country—leaders of science, as well as leading men of business—who are called upon to devise means for increasing the wealth of the country. In my travels, I found little or no distress in Norway and in Denmark. Norway, for example, has an area of a few thousand square miles; it is not naturally rich. She nevertheless maintains her own army and navy, has her system of universal education, and the most up-to-date University. Poverty is practically unknown. The miracle is accomplished through science by utilising to the utmost all the available resources of the country.

The Country’s Peril.

Need I say that unemployment and economic distress in India, on account of its magnitude, present a problem even more acute and dangerous than anywhere else? Is it not tragic that our country with great potential wealth should be in this terrible plight? There is a large number of young men who could be specially trained in the most advanced methods of science in efficiently conducted Institutes, the high standard of which should stand comparison with any in the world. This would remove many difficulties experienced by Indian students in Europe. It should also be our aim not to be so entirely dependent on foreign countries for our higher education and for our needs. For carrying out such a programme, a far-sighted and comprehensive State policy would be required. I am sure that the country would willingly meet the necessary large expenditure, provided that the money is spent here for benefiting and enriching India, and in opening out wider spheres of activity for her children. There is also a large field for enterprise, where Indians and Englishmen would, as partners, find opportunities for co-operation and higher appreciation of each other. While all activity is paralysed by dissensions, foreign nations, not over-friendly to Indian interests, are pursuing their policy of exploitation and consolidation of their claims on India’s resources. The peaceful penetration will inevitably lead to forceful occupation and division of India into different spheres of influence. There lies India’s great peril.

Knowledge in Service of Humanity.

The extension and utilisation of knowledge in the service of man is the true function of a centre of learning. We need not be discouraged by temporary aberrations of man, but we should be inspired by the nobility of his aspirations. It is not by passivity but by active struggle that we can serve the world in better ways. The weakling who has refused to take part in the conflict, having acquired nothing, has nothing to give or renounce. He alone, who has striven and won, can enrich the world by giving away the fruits of his victorious experience. The strong has thus taken the burden of the weak, a common sorrow having filled his life with pity and compassion. And no injunction could be more imperative on us than the ancient royal edict of Asoka inscribed on imperishable stone, twenty-two centuries ago:

“Go forth and intermingle and bring them to knowledge. Go forth among the terrible and powerful. both here and in foreign countries, in kindred ties of brotherhood and sisterhood, go everywhere!”

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Address given at the eighth anniversary meeting of the Bose Institute.

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1. Transactions, Bose Institute Vol I-IV. (1918—1923)
   Physiology of Ascent of Sap (1923)
   Physiology of Photosynthesis (1924)
   Nervous Mechanism in Plants (1925)