The movement of the main petiole seems
to be variable; we have seen it in the evening 27o lower than during the
day; but sometimes in nearly the same position. Nevertheless, a sinking
movement in the evening and a rising one during the night is probably the
normal course, for this was well-marked in the petiole of the first-formed
true leaf.
The circumnutation of the main petiole of a young leaf was traced during 2
3/4 days, and was considerable in extent, but less complex than that of M.
pudica. The movement was much more lateral than is usual with
circumnutating leaves, and this was the sole peculiarity which it
presented. The apex of one of the terminal leaflets was seen under the
microscope to travel 1/50 of an inch in 3 minutes.
Mimosa marginata.--The opposite leaflets rise up and approach each other at
night, but do not come into close contact, except in the case of very young
leaflets on vigorous shoots. Full-grown leaflets circumnutate during the
day slowly and on a small scale.
Schrankia uncinata (Tribe 20).--A leaf consists of two or three pairs of
pinnae, each bearing many small leaflets.
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