30 m. it formed a ring; and in from 5 to 6 hours
from being first hooked, it closely grasped the stick. A second
tendril acted at nearly the same rate; but I observed one that took
24 hours before it curled twice round a thin twig. Tendrils which
have caught nothing, spontaneously curl up to a close helix after the
interval of several days. Those which have curled round some object,
soon become a little thicker and tougher. The long and thin main
peduncle, though spontaneously moving, is not sensitive and never
clasps a support. Nor does it ever contract spirally, {33} although
a contraction of this kind apparently would have been of service to
the plant in climbing. Nevertheless it climbs pretty well without
this aid. The seed-capsules though light, are of enormous size
(hence its English name of balloon-vine), and as two or three are
carried on the same peduncle, the tendrils rising close to them may
be of service in preventing their being dashed to pieces by the wind.
In the hothouse the tendrils served simply for climbing.
The position of the tendrils alone suffices to show their homological
nature. In two instances one of two tendrils produced a flower at
its tip; this, however, did not prevent its acting properly and
curling round a twig.
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