Passiflora gracilis (Passifloracae).--The young leaves sleep by their
blades hanging vertically downwards, and the whole length of the petiole
then becomes somewhat curved downwards. Externally no trace of a pulvinus
can be seen. The petiole of the uppermost leaf on a young shoot stood at
10.45 A.M. at 33o above the horizon; and at 10.30 P.M., when the blade was
vertically dependent, at only 15o, so the petiole had fallen 18o. That of
the next older leaf fell only 7o. From some unknown cause the leaves do not
always sleep properly. The stem of a plant, which had stood for some time
before a north-east window, was secured to a stick at the base of a young
leaf, the blade of which was inclined at 40o below the horizon. From its
position the leaf had to be viewed obliquely, consequently the vertically
ascending and descending movements appeared when traced oblique. On the
first day (Oct. 12th) the leaf descended in a zigzag line until late in the
evening; and by 8.15 A.M. on the 13th had risen to nearly the same level as
on the previous morning. A new tracing was now begun (Fig.
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