A young leaf,
which with the
[page 240]
petiole was only 1.2 inch in length, had a filament fixed externally along
the midrib of the still closed lobes, which projected at right angles to
the petiole. In the evening this leaf completed an ellipse in the course of
2 h. On the following day (Sept. 25th) its movements were traced during 22
h.; and we see in Fig. 106 that it moved in the same general direction, due
to the straightening of the leaf, but in an extremely zigzag line. This
line represents several drawn-out or modified ellipses. There can therefore
be no doubt that this young leaf circumnutated.
Fig. 106. Dionaea muscipula: circumnutation of a young and expanding leaf,
traced on a horizontal glass in darkness, from noon Sept. 24th to 10 A.M.
25th. Apex of leaf 13 ? inches from the glass, so tracing considerably
magnified.
A rather old, horizontally extended leaf, with a filament attached along
the under side of the midrib, was next observed during 7 h. It hardly
moved, but when one of its sensitive hairs was touched, the blades closed,
though not very quickly.
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