Cuap. V. ROOT-CLIMBERS, 187 - 
of softening indurated caoutchouc, I soaked in it 
during a short time several rootlets of a plant which 
had grown up a plaistered wall; and I then found 
many extremely thin threads of transparent, not viscid, 
excessively elastic matter, precisely like caoutchouc, 
attached to two sets of rootlets on the same branch. 
These threads proceeded from the bark of the rootlet 
at one end, and at the other end were firmly attached 
to particles of silex or mortar from the wall. There 
could be no mistake in this observation, as I played 
with the threads for a long time under the microscope, 
drawing them out with my dissecting-needles and 
letting them spring back again. Yet I looked re- 
peatedly at other rootlets similarly treated, and could 
neyer again discover these elastic threads. I there- 
fore infer that the branch in question must have been 
slightly moved from the wall at some critical period, 
whilst the secretion was in the act of drying, through 
the absorption of its watery parts. The genus Ficus 
abounds with caoutchouc, and we may conclude from 
the facts just given that this substance, at first in 
solution and ultimately modified into an unelastic 
cement,* is used by the Ficus repens to cement its 
rootlets to any surface which it ascends. Whether 
other plants, which climb by their rootlets, emit 
any cement I do not know; but the rootlets of the 
* Mr. Spiller has recentlyshown a fine state of division to the air, 
(Chemical Society, Feb.16,1865), gradually becomes converted into 
in a paper on the oxidation of _ brittle, resinous matter, very similar 
india-rubber or caoutchouc, that to shell-lac. 
this substance, when exposed in 
