Dr. Bose had shown that all plants are sensitive--that there is no
difference between the so-called 'sensitive' and the supposed
'non-sensitive'--that they gave alike the true excitatory _electric
response_ as well as _motile response_. The evidence of plant's script
now removed beyond any doubt the long-standing error which divided the
vegetable world into 'sensitive' and 'insensitive.' There remained,
however, the question of nervous impulse in plants, the discovery of
which, though announced by Dr. Bose, ten years ago, did not yet find
full acceptance.
Finding that the scope of his investigation has been very much enlarged
by the devise of the Resonant Recorder, Dr. Bose proceeded to attack the
_current_ view "that there was no transmission of true excitation in
Mimosa, the propagated impulse being regarded as merely
hydromechanical." This conclusion was based on the experiments of the
leading German plant physiologists, Pfeffer and Haverlandt who failed to
bring on any variation in the propagated impulse in plants either by
scalding or by application of an anaesthetic. Dr. Bose pointed out that,
as Pfeffer applied the chloroform to the _outer_ stalk and Haverlandt
scalded the _outer_ stem, neither the stimulant nor the anaesthetic
reached the nerves. So he, instead of applying the stimulant or the
anaesthetic, in the _liquid_ form, to the outer stalk or stem, confined
the Mimosa, in a little chamber, and subjected it to the influence of
the _vapour_ of the drug. The fumes now penetrated and reached the
nerves and the plant was made to record, by its own script, the
variations, if any, produced by the drugs. The plant, by its self-made
records, showed exultation with alcohol, depression with chloroform,
rapid transmission of a shock with the application of heat, and an
abolition of the propagated impulse with the application of a deadly
poison like potassium cyanide. This variation in the transmitted
impulse, under physiological variations, showed that it was not a
physical one. This sealed the fate of the hydromechanical theory.
Dr. Bose went further and showed that the impulse is transmitted in both
directions along the nerve but not at the same rate. And, by interposing
an electric block, he arrested the nervous impulse in a plant in a
manner similar to the corresponding arrest in the animal nerve and
thereby produced nervous _paralysis_ in plant, such paralysis being
afterwards cured by appropriate treatment. "If he had made no other
discovery," says the Editor of the _Scientific American_ "Dr. Bose would
have earned an enduring reputation in the annals of science. We know
very little about paralysis in the human body, and practically nothing
about its cause. The nervous system of the higher animals is so
complicated, so intricate, that it is hard to understand its
derangement. The human nerve dies when isolated. It is killed by the
shock of removal, and responds for the moment abnormally and therefore
deceptively. But, if we study the simplest kind of a nerve,--and the
simplest is that of a plant,--we may hope to understand what occurs when
a hand or a foot cannot be made to move. To find out that plants have
nerves, to induce paralysis in such nerves and then to cure them--such
experiments will lead to discoveries that may ultimately enable
physicians to treat more rationally than they do, the various forms of
paralysis now regarded as incurable."