A new tracing was then
begun (not here given), and during 12 ? h. the leaf moved eight times up
and seven times down; so that it described 7 ? ellipses in this time, and
this is an extraordinary rate of movement. The summit of the petiole was
then secured to a stick, and the separate leaflets were found to be
continually circumnutating.
Fig. 103. Lupinus speciosus: circumnutation of leaf, traced on vertical
glass, from 10.15 A.M. to 5.45 P.M.; i.e., during 6 h. 30 m.
[page 237]
(12.) Echeveria stolonifera (Crassulaceae, Fam. 84).--The older leaves of
this plant are so thick and fleshy, and the young ones so short and broad,
that it seemed very improbable that any circumnutation could be detected. A
filament was fixed to a young upwardly inclined leaf, .75 inch in length
and .28 in breadth, which stood on the outside of a terminal rosette of
leaves, produced by a plant growing very vigorously. Its movement was
traced during 3 days, as here shown (Fig. 104). The course was chiefly in
an upward direction, and this may be attributed to the elongation of the
leaf through growth; but we see that the lines are strongly zigzag, and
that occasionally there was distinct circumnutation, though on a very small
scale.
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