Part 3

After he had come back, from the Second Scientific Deputation, the Government of India conferred on him the distinction of Companion of the Order of the Indian Empire, in 1903, in recognition of his valuable researches.

PLANT LIFE AND ANIMAL LIFE

Next Dr. Bose, in natural sequence to the investigation of the response in 'inorganic' matter commenced 'a prolonged study of the activities of plant life as compared with corresponding functioning of animal life.'

ALL PLANTS ARE "SENSITIVE"

It was believed that so-called 'sensitive' plants alone exhibited excitation by electric response. But Dr. Bose, believing in continuity of responsive phenomena, used the same experimental devices, with which he had already succeeded in obtaining the electric response of inorganic substances, to test whether ordinary plants also--meaning those usually regarded as 'insensitive'--would or would not exhibit excitatory electrical response to stimulus. With the help of very delicate instruments, Dr. Bose demonstrated the very startling fact that not only every plant, but every organ of every plant gave true excitatory electric response--and that response was not confined alone to 'sensitive' plants like Mimosa.

Dr. Bose then proceeded to investigate whether the responsive effects which he had shown to occur in ordinary plants might not be further exhibited by means of visible mechanical response, thus fully removing the distinction commonly assumed to exist between the 'sensitive' and supposed 'non-sensitive.' Dr. Bose invented 'special apparatus of extreme delicacy,' which detected infinitesimal tremors, and showed that ordinary plants, usually regarded as insensitive, gave motile responses, which had hitherto passed unnoticed. His later investigation shows 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 by a drifting cloud."

'TROPIC' MOVEMENTS

Finding that the plants give, not only electric but motile response as well, to stimulus, Dr. Bose proceeded to study the nature of responses evoked in plants by the stimuli of the natural forces. He found that plants respond visibly, by movements, to environmental stimuli. But the movements induced--'tropic' movements--are extremely diverse. Light, for example, induces sometimes positive curvature, sometimes negative. Gravitation, again, induces one movement in the root, and the opposition in the shoot. Dr. Bose applied himself to find out whether the movements in response to external stimuli, though apparently so diverse, could not be ultimately reduced to a fundamental unity of reaction. As a result of a very deep and penetrating study of the effects of various environmental stimuli, on different plant organs, he showed that the cells on two sides are unequally influenced, on account of different external conditions, and contract unequally, and hence the various movements are produced--that the many anomalous effects, hitherto ascribed to 'specific sensibilities,' are due to the 'differential sensibilities'--differential excitability of anisotropic structures and to the opposite effects of external and internal stimuli--that all varieties of plant movements are capable of a consistent mechanical explanation. Dr. Bose's "latest investigations recently communicated to the Royal Society have established the single fundamental reaction which underlies all these effects so extremely diverse."

EXTENDED APPLICATION OF MECHANICAL THEORY

With an extended application of his mechanical theory, Dr. Bose has gradually removed the veil of obscurity from many a phenomenon in plant life. The 'autonomous' movements of plants, for example, which remained enveloped in mystery, received a satisfactory solution at his hands.

'AUTONOMOUS' MOVEMENTS

It was believed that automatically pulsating tissues draw their energy from a mysterious "vital force" working within. By controlling external forces, Dr. Bose stopped the pulsation and re-started it and thus demonstrated that the 'automatic action' was not due to any internal vital force. He pointed out that the external stimulus--instead of causing, as was customary to suppose, an explosive chemical change and an inevitable run-down of energy--brings about an accumulation of energy by the plant. And with the accumulation of absorbed energy, a point is reached when there is an overflow--the excess of energy bubbles over, as it were, and shows itself in 'spontaneous' movements. The stimulus being strong a single response--a single twitching of the leaflets--is not enough to express the whole of the leaf's responsive energy and it yields a multiple response--it reverberates--it manifests itself in 'automatic' pulsations. When, however, the accumulated energy is exhausted, then there is also an end of 'spontaneous movements.' There are strictly speaking, no 'spontaneous' movements; those known by that name are really due either to the immediate effects of external stimulus or to the stimulus previously absorbed and held latent in the plant to find subsequent expression--due to the direct or indirect action of external forces which are transformed in the machinery of the plants in obedience to the principle of the Conservation of Energy.

"ASCENT OF SAP" "AND GROWTH"

Dr. Bose then showed that, not gross mechanical movements alone, but also other invisible movements are initiated by the action of stimulus, and that the various activities, such as the "ascent of sap" and "growth" are in reality different reactions to the stimulating action of energy supplied by the environment. In this way, Dr. Bose showed that several obscure phenomena, in the life-processes of the plant, can be very satisfactorily explained by the Mechanical Theory.

It would not be out of place to mention that Dr. Bose, to carry on his researches on the Ascent of Sap, invented a new type of instrument (Shoshungraph). And for an accurate investigation on the phenomenon of growth of plants he devised an instrument (Growth Recorder) for instantaneous measurement of the rate of growth and another instrument (Balanced Crescograph) for determining the influences of various agencies on growth. So very marvellous these instruments that the growth, which takes place, during a few beats of pendulum, is measured, and, in less than a quarter of an hour, the action of fertilizers, foods, electrical currents and various stimulants are determined. "What is the tale of Aladdin and his wonderful lamp" exclaims the Editor of the Scientific American "compared with the true story told by the crescograph?... Instead of waiting a whole season, perhaps years, to discover whether or not it is wise to mix this or that fertilizer with the soil one can now find in a few minutes!" Yet these are the instruments which are better known in Washington than in Calcutta! The question of their application to practical agriculture has excited more interest in the United States of America than in this unfortunate land, which is an essentially agricultural country!

FUNDAMENTAL IDENTITY OF REACTIONS

Dr. Bose showed that there is no physiological response given by the most highly organised animal tissue that is not also to be met with in the plant. He carried on "Researches on Diurnal Sleep" and showed that the plant is not equally sensitive to an external stimulus during day and night, and that there is a fundamental identity of life-reaction in plant and animal, as seen in a similar periodic insensibility in both, corresponding to what we call sleep. He also showed that the passage of life in the plant, as in the animal, is marked by an unmistakable spasm. He invented, an instrument (Morograph) with which he recorded the critical point of death of a plant with great exactness. He demonstrated, in the most conclusive manner, that there is an essential unity of physiological effects of drugs on plant and animal tissues and showed the modifications which are introduced into these effects by the factor of individual 'constitution.' It may be mentioned casually that "this physiological identity in the effect of drugs is regarded by leading physicians as of great significance in the scientific advance of Medicine; since 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." Dr. Bose further demonstrated that there is conduction of the excitatory impulse in the plant, like the nervous impulse in the animal; and showed the possibility of detecting the wave in transit and measured the speed with which the excitation coursed through the plant and also showed that the velocity of excitation is modified, by different agencies, even in the case of ordinary plants. He also showed that the polar effects induced by electric currents, both in plants and animals, are identical.

These remarkable researches on Plant Response have 'revolutionised in some respects and very much extended in others our knowledge of the response of plants to stimulus.'

FURTHER DIFFICULTIES

Dr. Bose communicated his paper 'On the Electric Pulsation accompanying Automatic Movements in Desmodium Gyrans' to the Linnaean Society, which was published, in December 1902. Then, in 1903, he communicated to the Royal Society his researches on 'Investigation on Mechanical Response in Plants,' 'On Polar effects of Currents on the Stimulation of Plants,' 'On the Velocity of Transmission of Excitatory waves in Plants,' 'On the excitability and conductivity of Plant Tissues,' 'On the Propagation of the Electromotive Wave concomitant of Excitatory Waves in Plants,' 'On Multiple Response in Plants,' 'On an enquiry into the cause of Automatic Movements.'

"These new contributions" made by Dr. Bose on Plant Response "were regarded as of such great importance that the Royal Society showed its special appreciation by recommending them to be published in their Philosophical Transactions. But the same influence, which had hitherto stood in his way, triumphed once more, and it was at the very last moment that the publication was withheld. The Royal Society, however, informed him that his results were of fundamental importance, but as they were so wholly unexpected and so opposed to the existing theories, that they would reserve their judgment until, at some future time, plants themselves could be made to record their answers to questions put to them. This was interpreted in certain quarters here as the final rejection of Dr. Bose's theories by the Royal Society and the limited facilities which he had in the prosecution of his researches were in danger of being withdrawn."

HE BUILT HIS LIFE ON THE ROCK OF FAITH

But these difficulties--sufficient to crush many a spirit--could hardly quench the ardour of his burning soul, which was 'hungering and thirsting' for the establishment of a truth in which he had a firm Faith. Though the surges would beat against him, he would not give way. With the true spirit of a Sadhak, he devoted himself to the realisation of the great dream of his life. And, for the next ten years, the one tap, jap and aradhana of his life--the one all-engrossing idea of his mind--was how to make the plant give testimony by means of its own autograph.

PUBLICATION OF "PLANT RESPONSE"

Though his researches did not find an outlet, in the Proceedings of the Royal Society, he did not lose heart. He brought out, in April 1906, a systematic treatise--"The Plant Response as a Means of Physiological Investigation"--in which he incorporated the results of his investigations on plant life.

ADOPTS A NEW METHOD OF INVESTIGATION

Hitherto Dr. Bose detected the various excitatory effects of plants by means of mechanical response. Being now confronted with opposition, he turned his attention to the finding of corroboration of the various results, which he had already obtained, by some other method of investigation. And for this he employed the method of electric response. He found that the results obtained by this new method of inquiry corroborated those already obtained by him by the old method. Emboldened by this corroboration, he next proceeded to extend this new method of inquiry by means of electric response into the field of Animal Physiology with a view to explain responsive phenomena in general on the consideration of that fundamental molecular reaction which occurs even in inorganic matter.'

RESULT OF THE INVESTIGATION