thought that the twisting of the axis caused the revolving movement;
but it is not possible that the twisting of the axis of the Hop three
times should have caused thirty-seven revolutions. Moreover, the
revolving movement commenced in the young internode before any
twisting of its axis could be detected. The internodes of a young
Siphomeris and Lecontea revolved during several days, but became
twisted only once round their own axes. The best evidence, however,
that the twisting does not cause the revolving movement is afforded
by many leaf-climbing and tendril-bearing plants (as Pisum sativum,
Echinocystis lobata, Bignonia capreolata, Eccremocarpus scaber, and
with the leaf-climbers, Solanum jasminoides and various species of
Clematis), of which the internodes are not twisted, but which, as we
shall hereafter see, regularly perform revolving movements like those
of true twining-plants. Moreover, according to Palm (pp. 30, 95) and
Mohl (p. 149), and Leon, {5} internodes may occasionally, and even
not very rarely, be found which are twisted in an opposite direction
to the other internodes on the same plant, and to the course of their
revolutions; and this, according to Leon (p. 356), is the case with
all the internodes of a certain variety of Phaseolus multiflorus.
Internodes which have become twisted round their own axes, if they
have not ceased to revolve, are still capable of twining round a
support, as I have several times observed.

Mohl has remarked (p. 111) that when a stem twines round a smooth
cylindrical stick, it does not become twisted. {6} Accordingly I
allowed kidney-beans to run up stretched string, and up smooth rods
of iron and glass, one-third of an inch in diameter, and they became
twisted only in that degree which follows as a mechanical necessity
from the spiral winding. The stems, on the other hand, which had
ascended ordinary rough sticks were all more or less and generally