Sir J. C. Bose delivered the following lecture on the 'Wounded Plants' at the Bose Institute, on the 7th February, 1919:—
It is a little over four years now that the Embodiment of World Tragedy stalked over Western Europe. The fair field of France and the bright sky was under a pall of battle-smoke. Our sight could not penetrate through the dense gloom, and the mortal cry of the wounded and dying, drowned by hoarse roar of a thousand did not reach our ear. But from the time the Sikh and the Pathan, the Gurkha and the Bengali, the Mahratta and the Rajput flung themselves in front of battle from that day our perception has become intensified. The distant cry of those whose life-blood has crimsoned the white field of snow, has found reverberating echo in our heart. What is that subtle bond by which all distances are bridged over, and by which an individual life becomes merged in larger life? Sympathy is that bond by which we come to realise the unity of all life. Before us are spread multitudinous plants, silent and seemingly impassive. They too like us are actors in the Cosmic drama of life, like us the play thing of destiny. In their checkered life, light and darkness, the warmth of summer and frost of winter, drought and rain, the gentle breeze and whirling tornadoes, life and death alternate. Various shocks impinge on them, but no cry is raised in answer. I shall nevertheless try to decipher some chapters of their life history.
When a man receives a blow or shock of any kind, his answering cry makes us realise that he is hurt, but a mute makes no outcry. How do we realise his sufferings? We know it by his agonised look by the convulsive movement of his limbs, and through fellow-feeling realise his pain. When a frog is struck it does not cry, but its limbs show convulsive movement. But from this it does not follow that the frog is not hurt, for some would urge that there is a great gap between us and lower animals. One who feels for the humblest of His creatures alone knows whether the frog is hurt or not. Human sympathy always aspires: it is sometimes extended to equals, hardly ever to inferiors. And so it happens that many would doubt, whether the lowly and the depressed possess the fine sense of the exalted to feel the same joy and sorrow, and to resent social tyranny. When human attitude is so finely discriminative as regards different grades of his own species, it might be extravagant to believe that the frog could have any consciousness of pain. A concession might however be made that the frog perceives a shock to which it responds by convulsive movements. It is as well that we should be careful about the use of terms for an eminent biologist insisted that animals never felt any pain: when an oyster is swallowed alive, it did not, according to him, feel any pain but rather a sensation of grateful warmth at contact with the alimentary tract. The question will remain undecided for no one has as yet returned from the gastric cavity of the tiger to expatiate on the exquisite sensation.
TEST OF LIVINGNESS
Responsive movements being a test of life, we shall try to construct a scale with which the height of livingness may be measured. What is the difference between the living and the dead? The living answers to a shock from without; the most lively gives the most energetic, the torpid or dying the feeblest, and the dead no answer at all. Thus life may be tested by shocks from without, the size of the answer being the gauge of vitality. The answer of the strong will be violent and almost explosive in its intensity, while the weakling will barely protest. The responsive movements may be recorded by suitable apparatus. The successive responses to similar shocks will remain uniform, if the living tissue remained always the same. But the living organism is always in a state of change for environment is always building us anew, and we are changing everyday of our life. We are thus subject to change, some day we are in a state of high exuberance, and other time in a state of lowest depression: we pass through numerous phases between the two extremes. Not merely does the present modify, but there is also the subtle impress of memory of the past. The sum total of all these characterise one individual from another. How is the hidden to be made manifest? To test the genuineness of a coin, we strike it and the sound response betrays the true from the false. The genuine rings true and the other gives a false note. In this way perhaps the inner history of different lives may be revealed by shocks and the resulting response.
EFFECT OF WOUND
There are three separate investigations that have been carried out on the effect of wound on plants: The first is the shock effect of wound on growth: this generally speaking retards or arrests growth. In the second series of investigations the change of spontaneous pulsation of the leaflet of the Telegraph plant was recorded. Death begins to spread from the cut end of the leaflet, and reaches the throbbing tissue which becomes permanently stilled on cessation of life. Experiments are in progress of arrest their march of death, and the cut leaflet which died in 24 hours has now been kept alive for more than a week.
PARALYSIS OF SENSIBILITY
Another series of investigations were carried out on the paralysing effect of severe wound. A leaf of Mimosa was cut off from the plant, and the subsequent histories of the wounded plant and the detached leaf are curiously different. The cutting of one of its leaves had caused a great shock to the parent plant, and an intense excitation spreads over to the distant organs. All the leaves remained depressed and irresponsive for several hours. From this state of paralysed sensibility, the plant gradually recovers and the leaves begin to show returning sensitiveness. The detached leaf, when placed in a nourishing solution soon recovers, and holds up its head with an attitude indicative of defiance, and the responses it gives are energetic. This lasts for twenty four hours, after which a curious change creeps in the vigour of its responses begins rapidly to wane. The leaf hitherto erect, falls over; death had at last asserted its mastery.