In certain tissues, a very curious phenomenon is observed. In man and
other animals, there are tissues which beat, as we say, spontaneously.
As long as life lasts, so long does the heart continue to pulsate. There
is no effect without a cause. How then was it that these pulsations
became spontaneous? To this query, no fully satisfactory answer has been
forthcoming. We find, however, that similar spontaneous movements are
also observable in plant tissues, and by their investigation the secret
of automatism in the animal may perhaps be unravelled.
Physiologists, in order to know the heart of man, play with those of the
frog and tortoise. "To know the heart," be it understood, is here meant
in a purely physical, and not in a poetic sense. For this it is not
always convenient to employ the whole of the frog. The heart is
therefore cut out, and make the subject of experiments, as to what
conditions accelerate, and what retard, the rate and amplitude of its
beat. When thus isolated, the heart tends of itself to come to a
standstill, but if, by means of fine tubing, it be then subjected to
interval blood pressure, its beating will be resumed, and will continue
uninterrupted for a long time. By the influence of warmth, the frequency
of the pulsation may be increased, but its amplitude diminished. Exactly
the reverse is the effect of cold. The natural rhythm and the amplitude
of the pulse undergo appropriate changes, again, under the action of
different drugs. Under either, the heart may come to a standstill, but
on blowing this off the beat is renewed. The action of chloroform is
more dangerous, any excess in the dose inducing permanent arrest.
Besides these, there are poisons also which arrest the heart beat, and a
very noticeable fact in this connection is, that some stop in a
contracted, and others in a relaxed condition. Knowing these opposed
effects, it is sometimes possible to counteract the effect of one poison
by administering another.
I have thus briefly stated some of the most important phenomena in
connection with spontaneous movements in animal tissues. Is it possible
that in plants also any parallel phenomena might be observed? In answer
to this question, I may say that I have found numerous instances of
automatic movements in plants.