perceptible in one petiole in between 4 hrs. 30 m. and 5 hrs., after
the suspension of a little loop of string. A loop of fine cotton
thread, weighing one sixteenth of a grain (4.05 mg.), not only caused
a petiole slowly to bend, but was ultimately so firmly clasped that
it could be withdrawn only by some little force. The petioles, when
coming into contact with a stick, take either a complete or half a
turn round it, and ultimately increase much in thickness. They do
not possess the power of spontaneously revolving.

Lophospermum scandens, var. purpureum.--Some long, moderately thin
internodes made four revolutions at an average rate of 3 hrs. 15 m.
The course pursued was very irregular, namely, an extremely narrow
ellipse, a large circle, an irregular spire or a zigzag line, and
sometimes the apex stood still. The young petioles, when brought by
the revolving movement into contact with sticks, clasped them, and
soon increased considerably in thickness. But they are not quite so
sensitive to a weight as those of the Rhodochiton, for loops of
thread weighing one-eighth of a grain did not always cause them to
bend.

This plant presents a case not observed by me in any other leaf-
climber or twiner, {22} namely, that the young internodes of the stem
are sensitive to a touch. When a petiole of this species clasps a
stick, it draws the base of the internode against it; and then the
internode itself bends towards the stick, which is caught between the
stem and the petiole as by a pair of pincers. The internode
afterwards straightens itself, excepting the part in actual contact
with the stick. Young internodes alone are sensitive, and these are
sensitive on all sides along their whole length. I made fifteen
trials by twice or thrice lightly rubbing with a thin twig several