45 A.M. June 2nd to 10.40 P.M. 6th.
With Coboea scandens, the young leaves, as they successively diverge from
the leading shoot which is bent to one side, rise up so as to project
vertically, and they retain this position for some time whilst the tendril
is revolving. The diverging and ascending movements of the petiole of one
such a leaf, were traced on a vertical glass under a skylight; and the
course pursued was in most parts nearly straight, but there were two
[page 271]
well-marked zigzags (one of them forming an angle of 112o), and this
indicates circumnutation.
The still closed lobes of a young leaf of Dionaea projected at right angles
to the petiole, and were in the act of slowly rising. A glass filament was
attached to the under side of the midrib, and its movements were traced on
a vertical glass. It circumnutated once in the evening, and on the next day
rose, as already described (see Fig. 106, p. 240), by a number of acutely
zigzag lines, closely approaching in character to ellipses. This movement
no doubt was due to epinasty, aided by apogeotropism, for the closed lobes
of a very young leaf on a plant which had been placed horizontally, moved
into nearly the same line with the petiole, as if the plant had stood
upright; but at the same time the lobes curved laterally upwards, and thus
occupied an unnatural position, obliquely to the plane of the foliaceous
petiole.
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