Climbing Plants 235 
rocks, or the trunks of large trees. The English- 
ivy, the poison-ivy, and the climbing-fig all 
clamber by this expedient, and their grip upon 
their supports is amazingly tenacious. 
Darwin observed that the rootlets of the climb- 
ing-fig, when they were a few days old, began to 
emit minute drops of a clear, viscid fluid. This 
fig is a first cousin to the plant which produces 
the india-rubber of commerce, and, like all 
members of the family, it abounds in caoutchouc. 
So the liquid which glues its rootlets to the wall 
is fluid india-rubber, and with time and exposure 
to the air this substance becomes converted into a 
brittle, resinous matter, very similar to shellac. 
‘‘ Whether other plants which climb by their root- 
lets emit any cement,” says Darwin, ‘‘I do not 
know; but the rootlets of the ivy, placed against 
glass, barely adhered to it, yet secreted a little 
yellowish matter.” 
But hook- and root-climbers, however lovely and 
pleasant to the landscape-gardener, have little in- 
terest for the student of plant habits. His at- 
tention is given rather to the twiners and tendril- 
bearers, whose movements seem instinct with life, 
akin to that of the animal world; for every tender 
tip of every growing twiner sweeps around and 
