VOL. XL NO 6

WHOLE NO. 240

[The great discoveries in photosynthesis placed the name of the eminent Russian, Prof. C. A. Timiriazeff of the Moscow University, in the foremost rank of plant-physiologists. In acknowledgment of his unique services in advancing physiology of plants, the honorary doctorate of the Cambridge University was conferred on him and he was also elected as the Foreign Member of the Royal Society. His scientific contributions are regarded as of such great importance that inspite of his being a foreigner, the great honour of delivering the Croonian lecture of the Royal Society was conferred on him. His discoveries have been simultaneously published in all European languages. He disproved the previously accepted view, that the yellow region of the spectrum, which is so bright to the eye, is the most effective region in the solar spectrum for photosynthesis. By his brilliant experimental method he was able to localise the maximum efficieney in the red region of the solar spectrum where the absorption of radiation by chlorophyll is greatest. His work on the "Life of Plant" is one of the most important contributions in plantphysiology. Its characteristic note is an exposition of plant structure and function based on physico-chemical processes at work in the living plant. In writing The History of Our Time Prof. Timiriazeff gives account of the epoch-making character of physiological researches carried out by Sir J. C. Bose. This article On Movements of Plants written in the Russian language is for the first time being translated and published by us in English, in the present issue. How profound has been the impression made on biological science by the discoveries of Professor Bose will be understood from the following extracts from the article of the eminent Russian savant in regard to the most important advances in physiological science. "We have become familiar during the last decades, with the part played by the Japanese. Now it is our fortune to witness the emergence of another and a still more ancient race, the Indian. The very name of this Indian savant is associated with a new era in the development of science in general. His classical work is remarkable for its brilliant

working out of experimental methods and for the deep significance of the conclusions which have all the appearance of a fresh triumph of scientific physiology" TRANSLATOR]

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very remarkable example of the application of exact physical methods to the physiology of plants, is afforded by the labours of the Indian savant whose very name indicates a new era in the development of science in general. We have become familiar during the last decades, with the part played in it by the Japanese. Now it is our fortune to witness the emergence of another, and a still more ancient race-the Indian. Indian. In wide circles of a society, which prides itself on its enlightenment, it is the custom to fall into raptures over the juggler's tricks of Indian fakirs, but for many of its members the news of the achievements of the great Indian savant in the field of positive science, will be an entirely unexpected novelty. It may, indeed, be doubted whether the activities of the well-known Indian physicist Jagadis Chandra Bose is not to be regarded as a the most brilliant example, in the advancement of modern science.

The results of which we propose to speak here, relate entirely to the twentieth century and form a whole series of labours, the first of which was presented to the International Congress of Physicists at the Paris Exhibition

* This very name, as also the names of his assistants mentioned by him, Guruprasanna and Surendra Chandra take us back to somewhere in the mythical world of the Mahabharata.

He proves that excitation is produced, as in the animal nerve, by the make of cathode and break of the anode. External stimulation, mechanical, physical, and chemical, act moreover not only at the part where they are applied, but the excitation is also transmitted to considerable distances in the plant. What is the nature of this transmission? The above-named German physiologists maintain that the transmission is exclusively hydrostatical. After setting forth the inadequacy of their arguments Bose proceeds to work out a method, the sensitiveness of which was adequate to the conditions of the problem. In order to accurately determine velocity of transmission of excitation it was necessary to find the exact value of the latent period. Bose's method enabled its magnitude to be determined accurately to 1/100 of a second. Given constant conditions, complete constancy was also attained in the results. The latent period for Mimosa was, on the average, 1/10 second. In the case of the less sensitive Neptunia, it amounted to as much as 6 seconds. The velocity of the transmission of movement in the petiole of Mimosa was 30 millimetres per second. Within certain limits the velocity of transmission increases with the increase of intensity of stimulation and with a rise of temperature. The velocity is also dependent on previous excitations, but the onset of fatigue lowers it. Conduction of excitation is observed in both directions, though not always with identical velocity. A whole series of experiments prove that the transmission of excitation is not hydrostatical but is of a protoplasmic character.

We pass from single to multiple responses. In the case of Biophytum and Averrhoa, a single moderate shock evokes one single response; a stronger shock evokes, however, series of successive responses.

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A remarkable conclusion follows from these experiments, that rhythmnic response does not necessarily presuppose a rhythmically repeated cause to produce it. On the contrary, the energy of a stimulus may be stored up, and pass over into a latent state which finds subsequent expression in repeated responses. This is analogous to the potential or latent energy of a spring in a state of tension, which when released,

The boundary line between multiple and spontaneous responses thus disappears. Biophytum normally capable only of single response may be compelled, by the application of stronger stimuli, to give multiple responses, which cannot be distinguished from automatic or spontaneous movements.

The small leaflets of Desmodium gyrans afford the classical example of spontaneous movements. When placed under unfavourable conditions, the plant ceases to exhibit these movements. It then reacts like Biophytum, by repeated reponses to strong stimulus and by a single response to weak stimulus. Biophytum thus becomes a connecting link between the single response of Mimosa and the enigmatical spontaneous movements of Desmodium.

This brings Bose to the final and most interesting chapter of his book-to the study of the movements of Desmodium, which by its mysterious "voluntary" movements furnishes the Vitalists with their last their last refuge. Says Bose:

"Up to the present no explanation of the socalled spontaneous movements has been offered. But in this and in my previous work, it has been shown that spontaneous movements have in fact no real existence that every movement results either from the action of an immediately antecedent stimulus, or of stimulus that has been stored and held latent.

That this is the case in Desmodium is proved by experiments on the isolation of the leaflets from external stimulations. Depletion of the store of energy then reveals itself by the gradual stoppage of pulsating movements. In this condition of