This cellular layer
apparently secretes some resinous cement; for its adhesion to the
wood was not lessened by an immersion of 24 hrs. in alcohol or water,
but was quite loosened by a similar immersion in ether or turpentine.
After a tendril has once firmly coiled itself round a stick, it is
difficult to imagine of what use the adhesive cellular layer can be.
Owing to the spiral contraction which soon ensues, the tendrils were
never able to remain, excepting in one instance, in contact with a
thick post or a nearly flat surface; if they had quickly become
attached by means of the adhesive layer, this would evidently have
been of service to the plant.
The tendrils of Bryonia dioica, Cucurbita ovifera, and Cucumis sativa
are sensitive and revolve. Whether the internodes likewise revolve I
did not observe. In Anguria Warscewiczii, the internodes, though
thick and stiff, revolve: in this plant the lower surface of the
tendril, some time after clasping a stick, produces a coarsely
cellular layer or cushion, which adapts itself closely to the wood,
like that formed by the tendril of the Hanburya; but it is not in the
least adhesive. In Zanonia Indica, which belongs to a different
tribe of the family, the forked tendrils and the internodes revolve
in periods between 2 hrs.
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