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of 80o F. The petiole
fell from 8 A.M. till 10.15 A.M., it then rose a little in a somewhat
zigzag line, often remaining stationary, till 5 P.M., when the great
evening fall commenced, which was continued till at least 10 P.M. By 7 A.M.
on the following morning it had risen to the same level as on the previous
morning, and then descended in a zigzag line. But from 10.30 A.M. till 4.15
P.M. it remained almost motionless, all power of movement being now lost.
The petiole, therefore, of this very old leaf, which must have long ceased
growing, moved periodically; but instead of circumnutating several times
during the day, it moved only twice down and twice up in the course of 24
h., with the ascending and descending lines not coincident.
It has already been stated that the pinnae move independently of the main
petiole. The petiole of a leaf was fixed to a cork support, close to the
point whence the four pinnae diverge, with a short fine filament cemented
longitudinally to one of the two terminal pinnae, and a graduated
semicircle was placed close beneath it.


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