in olive oil are powerfully affected.
Infusion and Decoction of Tea. Drops of a strong infusion and
decoction, as well as of a rather weak decoction, of tea were placed on
ten leaves, none of which became inflected. I afterwards tested three
of them by adding bits of meat to the drops which still remained on
their discs, and when I examined them after 24 hrs. they were closely
inflected. The chemical principle of tea, namely theine, was
subsequently tried and produced no effect. The albuminous matter which
the leaves must originally have contained, no doubt, had been rendered
insoluble by their having been completely dried.]
We thus see that, excluding the experiments with water, sixty-one
leaves were tried with drops of the [page 79] above-named
non-nitrogenous fluids; and the tentacles were not in a single case
inflected.
[With respect to nitrogenous fluids, the first which came to hand were
tried. The experiments were made at the same time and in exactly the
same manner as the foregoing. As it was immediately evident that these
fluids produced a great effect, I neglected in most cases to record how
soon the tentacles became inflected. But this always occurred in less
than 24 hrs.; whilst the drops of non-nitrogenous fluids which produced
no effect were observed in every case during a considerably longer
period.
Milk. Drops were placed on sixteen leaves, and the tentacles of all, as
well as the blades of several, soon became greatly inflected. The
periods were recorded in only three cases, namely, with leaves on which
unusually small drops had been placed. Their tentacles were somewhat
inflected in 45 m.; and after 7 hrs. 45 m. the blades of two were so
much curved inwards that they formed little cups enclosing the drops.
These leaves re-expanded on the third day. On another occasion the
blade of a leaf was much inflected in 5 hrs. after a drop of milk had
been placed on it.
Human Urine. Drops were placed on twelve leaves, and the tentacles of
all, with a single exception, became greatly inflected. Owing, I
presume, to differences in the chemical nature of the urine on
different occasions, the time required for the movements of the
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