These leaves, which moved so
little, had a fairly well-developed pulvinus. After an interval of some
weeks, when the same seedlings were 2 ? and 3 inches in height, some of the
young leaves stood up at night quite vertically, and others were highly
inclined; and so it was with bushes which were fully grown and were
flowering.
The movement of a leaf was traced from 9.15 A.M. on May 28th to 8.30 A.M.
on the 30th. The temperature was too low (15o - 16o C.), and the
illumination hardly sufficient; consequently the leaves did not become
quite so highly inclined at night, as they had done previously and as they
did subsequently in the hot-house: but the movements did not appear
otherwise disturbed. On the first day the leaf sank till 5.15 P.M.; it then
rose rapidly and greatly till 10.5 P.M., and only a little higher during
the rest of the night (Fig. 126). Early on the next day (29th) it fell in a
slightly zigzag line rapidly until 9 A.M., by which time it had reached
nearly the same place as on the previous morning. During the remainder of
the day it fell slowly, and zigzagged laterally.
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