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.
It is a remarkable fact that the mimosa is ten times as sensitive as a
frog in giving the response. And the native idea that plants are of a
lower order than animal life will cost many a sad disappointment.
In the course of his lecture Dr. Bose spoke of some of his startling
discoveries recently made.... The lecturer gave quite a spiritual turn
to his discourse as he finished it with the remark that, as it has been
the earnest endeavour of scientists to minimise material friction in
order to get the best results, so in our human concerns, it should be
our best aim to minimise friction,--which is, Ignorance.
--_Modern Review_, Vol. XII, pages 314-315.