MOTION AND SENSITIVENESS IN CLIMBING PLANTS. 
61 
Cobcea scandens furnishes many points for observation worthy 
of note. We can only give one. The tendril being vertical, 
sweeps a circle right oyer the axis of the stem which is turned 
to one side. As soon as the tendril comes in contact with a stick, 
the branches commence lifting themselves up and down, and 
arrange themselves in conformity with every irregularity of 
the surface, and so bring the hooks with which the extremities 
of the tendrils are furnished, originally facing in various 
directions, into contact with the wood. Mr. Darwin thus 
describes the beautiful adaptation of this plant : — 
“ A tendril caught a thin stick by the hooks of one of its two extreme 
branches ; though thus held by the tip, it continued to try and revolve, 
bowing itself out to all sides, and thus moving its branches ; the other ex- 
treme branch soon caught the stick ; the first branch immediately loosed itself, 
and then, arranging itself afresh, again caught hold. After a time, from the 
continued movement of the tendril, a third branch became caught by a single 
extreme hook .... the main stem now began to contract into an open spire, 
and thus to shorten itself ; and so, as it continued to try to revolve, a fourth 
branch was brought into contact. As the spiral contraction travelled down 
the main stem and down the branches of the tendril, all the lower branches, 
one after another, were brought into contact with the stick, and were wound 
round it and round their own branches, until the whole was tied into an 
inextricable knot round the stick. The branches of the tendril now became 
rigid, and even stronger than they were at first. This plant is secured to its 
support in a perfect manner.” 
Corydalis claviculata. — Of tbis plant we bave introduced a 
figure (PL V., fig. 6), because it affords an instance of an 
actual state of transition from a leaf-climber to a tendril 
bearer. In a full-grown plant all the leaves have their ex- 
tremities more or less converted into tendrils. All the 
reduced leaflets have branching nerves, and terminate in 
little spines like the fully developed leaflets. Every gradation 
can be traced until we come to branchlets u, and d , which 
show no vestige of a lamina. The terminal branches are highly 
sensitive, the sensibility of the petiole gradually diminishing 
from the tendril-like extremities to the base. The internodes 
are not at all sensitive. 
We must now pass on to the order 
Vitacece. — In this, in Sapindacece, and in Passifloracece , the 
tendrils are modified flower peduncles. Vitis vinifera, common 
vine. The tendril is of great size and thickness, sometimes 
sixteen inches in length. It consists of a peduncle, bearing 
two branches, which diverge equally from it like the letter Y 
(PI. VI., fig. 7). One branch (b) has a scale at the base, and 
is the longer, and often bifurcated. After a tendril has clasped 
