to 3 hrs. to have curled a
little inwards; and, under favourable circumstances, it curls round
and permanently seizes an object in from 8 hrs. to 10 hrs. The hook
when first formed, before the leaf has bent downwards, is but little
sensitive. If it catches hold of nothing, it remains open and
sensitive for a long time; ultimately the extremity spontaneously and
slowly curls inwards, and makes a button-like, flat, spiral coil at
the end of the leaf. One leaf was watched, and the hook remained
open for thirty-three days; but during the last week the tip had
curled so much inwards that only a very thin twig could have been
inserted within it. As soon as the tip has curled so much inwards
that the hook is converted into a ring, its sensibility is lost; but
as long as it remains open some sensibility is retained.
Whilst the plant was only about six inches in height, the leaves,
four or five in number, were broader than those subsequently
produced; their soft and but little-attenuated tips were not
sensitive, and did not form hooks; nor did the stem then revolve. At
this early period of growth, the plant can support itself; its
climbing powers are not required, and consequently are not developed.
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