These are mute companions, silently, growing beside our door, have now told us the tale of their life-tremulousness and their death spasm, in script that is as inarticulate as they. May it not be said that this their story has a pathos of its own, beyond any that the poets have conceived?
MARVELS OF PLANT LIFE
On the 8th June 1912, Dr J. C. Bose, who had gone to Advaita Ashrama, Mayavati, on a holiday trip, gave an illuminating discourse on the marvels of plant life.
He began by stating that a stimulus takes a certain time before it gets a response. This stimulus may be of different forms, e.g., it may be a sound stimulus, a light stimulus, an electric stimulus, and so on. The feebler the stimulus, the greater is the time it takes to elicit the response. For instance if one is called by a distant voice, one doubts whether he has been called at all, but in the case of a piercing scream, he starts up at once.
Now, the difficulty is that when the stimulus, the blow, is so strong as to get an instantaneous response, how is one to measure this infinitesimal time between the blow and the response? And this must be done absolutely free from any personal interference, so as to ensure correct results.
Dr. Bose here described how after deep thought and careful experiments and researches of several years he invented and manufactured a highly sensitive instrument which could automatically record the "response time" of a plant even to one thousandth part of a second. And in order to convey a graphic idea of the principles under which it worked, he had even made by means of a few simple things a crude form of his instrument, which helped the audience to form a clear idea of how a shock given to a plant which was experimented upon, would be recorded automatically by the apparatus by means of dots on its writing pad, and also how to ascertain the exact time each plant took to respond to the stimulus received. Thus the plant now records its own history unerringly by its own hand as it were. And that the same results are obtained each time the experiment is repeated under similar conditions, shows that this recording of the response time is a scientific phenomenon.
As an example of the similarities of reactions in plant and animal, Prof. Bose described the rhythmic activities of certain plants, in which automatic pulsations are maintained as in the animal heart. This phenomenon is exemplified by the Telegraph plant, which grows wild in the Gangetic plane; its Indian name is Bon charal or 'forest churl', the popular belief being that it dances to the clapping of the hand. There is no foundation however for this belief. It is a papilionaceous plant with trifoliate leaves, of which the terminal leaflet is large, and the two lateral, very small. Each of these is inserted on the petiole by means of pulvinule. The lateral leaflets are seen to execute pulsating movements which are apparently uncaused, and are not unlike the rhythmic movement of the heart to which we shall see later that their resemblance is more than superficial.
In the intact plant, under favourable conditions, these movements are easily observed to take place more or less continuously; but there are times when they come to a standstill. For this reason and because of the fact that a large plant cannot easily be manipulated as a whole and subjected to various changing conditions which the purpose of the investigation demands, it is desirable, if possible, to experiment with the detached petiole, carrying the pulsating leaflet. The required amputation however may be followed by arrest of the pulsating movements. But, as in the case of the isolated heart in a state of standstill, Dr. Bose found that the movement of the leaflet can be renewed, in the detached specimen, by the application of the internal hydrostatic pressure. Under these conditions, the rhythmic pulsations are easily maintained uniform for several hours. This is a great advantage, in as much as in the undetached specimen, the pulsations are not usually found to be so regular as they now become. So small a specimen, again, can easily be subjected to changing experimental conditions, such as the variation of internal hydrostatic pressure and temperature, application of different drugs, vapours and gases.
Under varying conditions the same plant has been observed to take different response times, as for instance, less in heat than in cold, less in summer than in winter, less in the morning than in the evening, and so forth. Again, different plants have different response times.