Part 4

Dr. Bose found, in the plant as well as in the animal, "a similar series of excitatory effects, whether these be exhibited mechanically or electrically. Both alike are responsive, and similarly responsive, to all the diverse forms of stimulus that impinge upon them. We ascend, in the one case as in the other, from the simplicities of the isotropic to the complexities of the anisotropic; and the laws of these isotropic and anisotropic responses are the same in both. The responsive peculiarities of epidermis, epithelium, and gland; the response of the digestive organ, with its phasic alterations; and the excitatory electrical discharge of an anisotropic plate, are the same in the plant as in the animal. The plant, like the animal, is a single organic whole, all its different parts being connected, and their activities co-ordinated, by the agency of those conducting strands which are known as nerves. As in the plant nerve, moreover, so also in the animal, stimulation gives rise to two distinct impulses, exhibiting themselves by two-fold mechanical and electrical indications of opposite signs.... The dual qualities or tones known to us in sensation, further, are correspondent with those two different nervous impulses, of opposite signs, which are occasioned by stimulation. These two sensory responses--positive and negative, pleasure and pain--are found to be subject to the same modifications, under parallel conditions, as the positive and negative mechanical and electrical indications with which they are associated. And finally, perhaps, the most significant example for the effect of induced anisotropy lies in that differential impression made by stimulus on the sensory surfaces, which remains latent, and capable of revival, as the memory-image. In this demonstration of continuity, then, it has been found that the dividing frontiers between Physics, Physiology, and Psychology have disappeared."

CLASH WITH CURRENT VIEWS

The results, which Dr. Bose obtained from actual experiments, clashed, however, with the theories in vogue. The reactions of different issues were hitherto regarded as special differences. As against this, a continuity is shown to exist between them. Thus, nerve was universally regarded as typically non-motile; its responses were believed to be characteristically different from those of muscle. Dr. Bose, however, has shown that nerve is indisputably motile and that the characteristic variations in the response of nerve are, generally speaking, similar to those of the muscle.

It was customary to regard plants as devoid of the power to conduct true excitation. Dr. Bose had already shown that this view was incorrect. He now showed, by experiment, that the response of the isolated vegetal nerve is indistinguishable from that of animal nerve, throughout a large series of parallel variations of condition. So complete, indeed, is the similarity between the responses of plant and animal, found, of which this is one instance, that the discovery of a given responsive characteristic in one case proves a sure guide to its observation in the other, and the explanation of phenomenon, under the simpler conditions of the plant, is found fully sufficient for its elucidation under the more complex circumstances of the animal. Dr. Bose found 'differential excitability' is widely present as a factor in determining the character of special responses and showed that many anomalous conclusions, with regard to the response of certain animal tissues, had arisen from the failure to take account of the 'differential excitability' of anisotropic organs. Hitherto Pfluger's Law of the polar effects of currents was supposed to rest on secure foundations. But Dr. Bose showed that Pfluger's Law was not of such universal application as was supposed. He demonstrated that, above and below a certain range of electromotive intensity, the polar effects of currents are precisely opposite to those enunciated by Pfluger.

SENSATION

It was supposed that nervous impulse, which, must necessarily form the basis of sensation, was beyond any conceivable power of visual scrutiny. But Dr. Bose showed that this impulse is actually attended by change of form, and is, therefore capable of direct observation. He also showed that the disturbance, instead of being single, is of two different kinds--viz., one of expansion (positive) and the other of contraction (negative)--and that, when the stimulus is feeble, the positive is transmitted, and, when the stimulus is stronger, both positive and negative are transmitted, but the negative, however, being more intense, masks the positive. He identified the wave of expansion travelling along the nerve with the tendency to pleasure, and the wave of contraction, with the tendency to pain. It thus appears that all pain contains an element of pleasure, and that pleasure, if carried too far becomes pain--that "the tone of our sensation is determined by the intensity of nervous excitation that reaches the central perceiving organ."

MEMORY IMAGE AND ITS REVIVAL

Dr. Bose next pointed out that there remains, for every response, a certain residual effect. A substance, which has responded to a given stimulus, retains, as an after-effect, a 'latent impression' of that stimulus and this 'latent impression' is capable of subsequent revival by bringing about the original condition of excitation. The impress made by the action of stimulus, though it remains latent and invisible, can be revived by the impact of a fresh excitatory impulse.

Experimenting with a metallic leaf, Dr. Bose demonstrated the revival of a latent impression under the action of diffused stimulus. The investigation by Dr. Bose on the after-effects of stimulus has thrown some light on the obscure phenomenon, of 'memory.' It appears that, when there is a mental revival of past experience, the diffuse impulse of the 'will' acts on the sensory surface, which contains the latent impression and re-awakens the image which appears to have faded out. Memory is concerned, thus, with the after-effect of an impression induced by a stimulus. It differs from ordinary sensation in the fact that the stimulus which evokes the response, instead of being external and objective, is merely psychic and subjective.

Dr. Bose has, by experimental devises, shown the possibility of tracing 'memory-impression' backwards even in inorganic matter, such latent impression being capable of subsequent revival. An investigation of the after-effects of stimulus, on living tissues would open out the great problem of the influence of past events on our present condition.

DEATH-STRUGGLE AND MEMORY REVIVAL

There is a wide-spread belief that, in the case of a sudden death-struggle, as for example, when drowning, the memory, of the past comes in a flash. "Assuming the correctness of this," says Sir Jagadis "certain experimental results which I have obtained may be pertinent to the subject. The experiment consisted in finding whether the plant, near the point of death, gave any signal of the approaching crisis. I found that at this critical moment a sudden electrical spasm sweeps through every part of the organism. Such a strong and diffused stimulation--now involuntary--may be expected in a human subject to crowd into one brief flash a panoramic succession, of all the memory images latent in the organism."

"COMPARATIVE ELECTRO-PHYSIOLOGY"

Dr. Bose published the results of these new researches, in 1907, in another remarkable volume, which was styled 'The Comparative Electro-Physiology.'

THIRD SCIENTIFIC DEPUTATION, 1907-08

After the publication of 'The Comparative Electro-Physiology,' the Government of India again sent Dr. Bose on a Scientific Deputation. He went over to England and America and placed the results of his researches before the learned Scientific Bodies. He read a paper 'On Mechanical Response of Plants' at the Liverpool meeting of British Association, in 1907. He then read a paper on 'The Oscillating Recorder for Automatic Tracing of Plant Movements' before the New York Academy of Sciences, and, in December 1908, he gave an address on 'Mechanical and Electrical Response in Plants,' at the Annual Meeting of the American Association for the Advancement of Science, held at Baltimore, and, in January 1909, he delivered a lecture on 'Growth Response of Plants' before the United States Department of Agriculture and, in February 1909, he read a paper on 'Death-spasm in Plants,' before the University of Illinois, and, in March 1909, a paper on 'Multiple and Autonomous Response in Plants' before the Madison University. He also lectured before the New York Botanical Society, the Medical Society of Boston, the Society of Western Electric Engineers at Chicago. He also delivered a series of post-graduate lectures on Electro-Physics and Plant Physiology at the Universities of Wisconsin, Chicago, Ann Arbor. He returned to India, in July 1909.

FURTHER EXPERIMENTAL EXPLORATION

By his new and newer methods of investigation, Dr. Bose got a deep and deeper perception of that underlying unity, for the demonstration of which he had been labouring since 1901. But the dream of his life was not yet realised. No direct method of obtaining response record was yet obtained. Hitherto the response recorder employed was a modification of the optical lever, automatic records being secured by the very inconvenient and tedious process of photography (which again introduced complications by subjecting a plant to darkness and thereby modifying its normal excitability); and the plant was not automatically excited by stimulus, besides the results obtained were liable to be influenced by personal factor. So Dr. Bose set about the invention of an apparatus, which should discard the use of photography and in which 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. Great difficulties were encountered in realising these ideal requirements. They appeared, at first, to be insurmountable. But, with continuous toil and persistence, Dr. Bose succeeded in designing a long battery of supersensitive instruments and apparatus, which made the seeming impossible possible. His ingenious "Resonant and Oscillating Recorders" gave a simple and direct method of obtaining the record. The plant, being automatically excited by stimulus, made its own responsive record. The closed doors, at last, opened. The secret of plant life stood revealed by the autographs of the plant itself. The great sadhana of his life now received its fulfilment. "It has been beautifully said--and it is a law of the moral world as unchangeable as physical laws--'Ask, and it shall be given you; seek, and ye shall find; knock, and it shall be opened unto you; for every one that asketh receiveth; and he that seeketh findeth and to him that knocketh it shall be opened."

TRANSMISSION OF EXCITATION IN MIMOSA

Dr. Bose had shown that all plants are sensitive--that there is no difference between the so-called 'sensitive' and the supposed 'non-sensitive'--that they gave alike the true excitatory electric response as well as motile response. The evidence of plant's script now removed beyond any doubt the long-standing error which divided the vegetable world into 'sensitive' and 'insensitive.' There remained, however, the question of nervous impulse in plants, the discovery of which, though announced by Dr. Bose, ten years ago, did not yet find full acceptance.

Finding that the scope of his investigation has been very much enlarged by the devise of the Resonant Recorder, Dr. Bose proceeded to attack the current view "that there was no transmission of true excitation in Mimosa, the propagated impulse being regarded as merely hydromechanical." This conclusion was based on the experiments of the leading German plant physiologists, Pfeffer and Haverlandt who failed to bring on any variation in the propagated impulse in plants either by scalding or by application of an anaesthetic. Dr. Bose pointed out that, as Pfeffer applied the chloroform to the outer stalk and Haverlandt scalded the outer stem, neither the stimulant nor the anaesthetic reached the nerves. So he, instead of applying the stimulant or the anaesthetic, in the liquid form, to the outer stalk or stem, confined the Mimosa, in a little chamber, and subjected it to the influence of the vapour of the drug. The fumes now penetrated and reached the nerves and the plant was made to record, by its own script, the variations, if any, produced by the drugs. The plant, by its self-made records, showed exultation with alcohol, depression with chloroform, rapid transmission of a shock with the application of heat, and an abolition of the propagated impulse with the application of a deadly poison like potassium cyanide. This variation in the transmitted impulse, under physiological variations, showed that it was not a physical one. This sealed the fate of the hydromechanical theory.

Dr. Bose went further and showed that the impulse is transmitted in both directions along the nerve but not at the same rate. And, by interposing an electric block, he arrested the nervous impulse in a plant in a manner similar to the corresponding arrest in the animal nerve and thereby produced nervous paralysis in plant, such paralysis being afterwards cured by appropriate treatment. "If he had made no other discovery," says the Editor of the Scientific American "Dr. Bose would have earned an enduring reputation in the annals of science. We know very little about paralysis in the human body, and practically nothing about its cause. The nervous system of the higher animals is so complicated, so intricate, that it is hard to understand its derangement. The human nerve dies when isolated. It is killed by the shock of removal, and responds for the moment abnormally and therefore deceptively. But, if we study the simplest kind of a nerve,--and the simplest is that of a plant,--we may hope to understand what occurs when a hand or a foot cannot be made to move. To find out that plants have nerves, to induce paralysis in such nerves and then to cure them--such experiments will lead to discoveries that may ultimately enable physicians to treat more rationally than they do, the various forms of paralysis now regarded as incurable."

MIMOSA AND MAN

Dr. Bose showed not only that the nervous impulse in plant and in man is exalted or inhibited under identical conditions but carried the parallelism very far and pointed out the blighting effects on life of a complete seclusion and protection from the world outside. "A plant carefully protected under glass from outside shocks", says Sir Jagadis "looks sleek and flourishing; but its higher nervous function is then found to be atrophied. But when a succession of blows is rained on this effete and bloated specimen, the shocks themselves create nervous channels and arouse anew the deteriorated nature. And is it not shocks of adversity, and not cotton-wool protection, that evolve true manhood?"

ROYAL SOCIETY

Having found that his investigation on Mimosa had broken down the barriers which separated kindred phenomena, Dr. Bose next communicated the results of his wonderful researches to the Royal Society. His paper was read, at a meeting of the Society, held on the 6th March 1913. The Royal Society now found that Dr. Bose had rendered the seemingly impossible, possible--had made the plant tell its own story by means of its self-made records. It could no longer withhold the recognition which was his due. The barred gates, at last, opened and the paper of Dr. Bose "On an Automatic Method, for the investigation of the Velocity of Transmission of Excitation in Mimosa" found publication in the "Philosophical Transactions of the Royal Society" in Vol. 204, Series B.

HIS FURTHER INVESTIGATIONS

Dr. Bose next pursued with great vigour his investigations on the Irritability of Plants. By making the plant tell its own story, by means of its self-made records, he showed that there is hardly any phenomenon of irritability observed in the animal which is not also found in the plant and that the various manifestations of irritability in the plant are identical with those in the animal and that many difficult problems in Animal Physiology find their solution in the experimental study of corresponding problems under simpler conditions of vegetable life.