From the course
pursued on the second day, when the plant had accommodated itself to the
light from above, there cannot be much doubt that the leaves undergo a
daily periodic movement, sinking during the day and rising at night.
(18.) Mutisia clematis (Compositae).--The leaves terminate in tendrils and
circumnutate like those of other tendril-bearers; but this plant is here
mentioned, on account of an erroneous statement* which has been published,
namely, that the leaves sink at night and rise during the day. The leaves
which behaved in this manner had been kept for some days in a northern room
and had not been sufficiently illuminated. A plant therefore was left
undisturbed in the hot-house, and three leaves had their angles measured at
noon and at 10 P.M. All three were inclined a little beneath the horizon at
noon, but one stood at night 2o, the second 21o, and the third 10o higher
than in the middle of the day; so that instead of sinking they rise a
little at night.
(19.) Cyclamen Persicum (Primulaceae, Fam. 135).--A young leaf, 1.8 of an
inch in length, petiole included, produced by an old root-stock, was
observed during three days in the usual manner (Fig.
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