15 P.M. it stood at 65o, and on the following early morning at 11o
beneath the horizon. The circumnutation of another young leaf (with its
petiole only 3 1/4 inches, and the blade 4 inches in length), was traced on
a vertical glass during 48 h.; it was dimly illuminated through a skylight,
and this seemed to disturb the proper periodicity of its movements.
Nevertheless, the leaf fell greatly during both afternoons, till either
7.10 P.M. or 9 P.M., when it rose a little and moved laterally. By an early
hour on both mornings, it had assumed its diurnal position. The well-marked
lateral movement for a short time in the early part of the night, was the
only interesting fact which it presented, as this caused the ascending and
descending lines not to coincide, in accordance with the general rule with
circumnutating organs. The movements of the leaves of this plant are thus
of the most simple kind; and the tracing is not worth giving. We have seen
that in another genus of the Aroideae, namely, Pistia, the leaves
[page 391]
rise so much at night that they may almost be said to sleep.
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