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"The Power of Movement in Plants"

M. and at 1 A.M. the leaflet
was still jerking rapidly; at 3.30 A.M. it was not seen to jerk, but was
observed during only a short time. It was, however, now inclined at a much
lower angle than that occupied at 1 A.M. At 6.30 A.M. (temp. 61o F.) its
inclination was still less than before, and again less at 6.45 A.M.; by
7.40 A.M. it had risen, and at 8.30 A.M. was again seen to jerk. This
leaflet, therefore, was moving during the whole night, and the movement was
by jerks up to 1 A.M. (and possibly later) and again at 8.30 A.M., though
the temperature was only 61o to 62o F. We must therefore conclude that the
lateral leaflets produced by young plants differ somewhat in constitution
from those on older plants.
In the large genus Desmodium by far the greater number of the species are
trifoliate; but some are unifoliate, and even the same plant may bear uni-
and trifoliate leaves. In most of the species the lateral leaflets are only
a little smaller than the terminal one. Therefore the lateral leaflets of
D. gyrans (see Fig. 148) must be considered as almost rudimentary.


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