had elapsed. Loops of thread weighing one-fourth of a grain, left
suspended on the lower petioles (f to l) during several days,
produced no effect. Yet the three petioles f, g, and h were not
quite insensible, for when left in contact with a stick for a day or
two they slowly curled round it. Thus the sensibility of the petiole
gradually diminishes from the tendril-like extremity to the base.
The internodes of the stem are not at all sensitive, which makes
Mohl's statement that they are sometimes converted into tendrils the
more surprising, not to say improbable.
The whole leaf, whilst young and sensitive, stands almost vertically
upwards, as we have seen to be the case with many tendrils. It is in
continual movement, and one that I observed swept at an average rate
of about 2 hrs. for each revolution, large, though irregular,
ellipses, which were sometimes narrow, sometimes broad, with their
longer axes directed to different points of the compass. The young
internodes, likewise revolved irregularly in ellipses or spires; so
that by these combined movements a considerable space was swept for a
support. If the terminal and attenuated portion of a petiole fails
to seize any object, it ultimately bends downwards and inwards, and
soon loses all irritability and power of movement.
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