124 TENDRIL-BEARERS. Cuap. III. 
petioles (f to 1) 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-ike extremity to the base. The in- 
ternodes of the stem are not at all sensitive, which 
makes Mohl’s statement that they are sometimes con- 
verted 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 move- 
ment, 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 inter- 
nodes, likewise revolved irregularly in ellipses or 
spires; so that by these combined movements a con- 
siderable 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. 
This bending down differs much in nature from that 
which occurs with the extremities of the young leaves 
in many species of Clematis; for these, when thus 
bent downwards or hooked, first acquire their full 
degree of sensitiveness. 
Dicentra thalictrifolia—In this allied plant the 
