82 and 1.64 of a grain sometimes caused a slight
curvature; but they were never closely clasped, as were the far
lighter loops of thread by the petioles.
In the nine vigorous plants observed by me, it is certain that
neither the slight spontaneous movements nor the slight sensitiveness
of the flower-peduncles aided the plants in climbing. If any member
of the Scrophulariaceae had possessed tendrils produced by the
modification of flower-peduncles, I should have thought that this
species of Maurandia had perhaps retained a useless or rudimentary
vestige of a former habit; but this view cannot be maintained. We
may suspect that, owing to the principle of correlation, the power of
movement has been transferred to the flower-peduncles from the young
internodes, and sensitiveness from the young petioles. But to
whatever cause these capacities are due, the case is interesting;
for, by a little increase in power through natural selection, they
might easily have been rendered as useful to the plant in climbing,
as are the flower-peduncles (hereafter to be described) of Vitis or
Cardiospermum.
Rhodochiton volubile.--A long flexible shoot swept a large circle,
following the sun, in 5 hrs.
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