I likewise repeatedly flirted small drops of water from a
brush on many tendrils, and syringed others so violently that the
whole tendril was dashed about, but they never became curved. The
impact from the drops of water was felt far more distinctly on my
hand than that from the loops of thread (weighing one thirty-second
of a grain) when allowed to fall on it from a height, and these
loops, which caused the tendrils to become curved, had been placed
most gently on them. Hence it is clear, that the tendrils either
have become habituated to the touch of other tendrils and drops of
rain, or that they were from the first rendered sensitive only to
prolonged though excessively slight pressure of solid objects, with
the exclusion of that from other tendrils. To show the difference in
the kind of sensitiveness in different plants and likewise to show
the force of the syringe used, I may add that the lightest jet from
it instantly caused the leaves of a Mimosa to close; whereas the loop
of thread weighing one thirty-second of a grain, when rolled into a
ball and placed gently on the glands at the bases of the leaflets of
the Mimosa, caused no action.
Passiflora punctata.
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