Cuar. IL. LEAF-CLIMBERS. 83 
seize distant objects. The petioles of the perfect 
leaves of Tropxolum tricolorum, as well as the tendril- 
like filaments of the plants whilst young, ultimately 
move towards the stem or the supporting stick, which 
they then clasp. These petioles and filaments also 
show some tendency to contract spirally. The tips of 
the uncaught leaves of the Gloriosa, as they grow old, 
contract into a flat spire or helix. These several facts 
are interesting in relation to true tendrils. 
With leaf climbers, as with twining plants, the first 
internodes which rise from the ground do not, at least 
im the cases observed by me, spontaneously revolve ; 
nor are the petioles or tips of the first-formed leaves 
sensitive. In certain species of Clematis, the large size 
of the leaves, together with their habit of revolving, 
and the extreme sensitiveness of their petioles, appear 
to render the revolving movement of the internodes 
superfluous; and this latter power has consequently 
become much enfeebled. In certain species of Tro- 
pxolum, both the spontaneous movements of the inter- 
nodes and the sensitiveness of the petioles have become 
much enfeebled, and in one species have been com- 
pletely lost. 
