Clematis vitalba.--The plants were in pots and not healthy, so that I
dare not trust my observations, which indicate much similarity in
habits with C. flammula. I mention this species only because I have
seen many proofs that the petioles in a state of nature are excited
to movement by very slight pressure. For instance, I have found them
embracing thin withered blades of grass, the soft young leaves of a
maple, and the flower-peduncles of the quaking-grass or Briza. The
latter are about as thick as the hair of a man's beard, but they were
completely surrounded and clasped. The petioles of a leaf, so young
that none of the leaflets were expanded, had partially seized a twig.
Those of almost all the old leaves, even when unattached to any
object, are much convoluted; but this is owing to their having come,
whilst young, into contact during several hours with some object
subsequently removed. With none of the above-described species,
cultivated in pots and carefully observed, was there any permanent
bending of the petioles without the stimulus of contact. In winter,
the blades of the leaves of C. vitalba drop off; but the petioles (as
was observed by Mohl) remain attached to the branches, sometimes
during two seasons; and, being convoluted, they curiously resemble
true tendrils, such as those possessed by the allied genus Naravelia.
The petioles which have clasped some object become much more stiff,
hard, and polished than those which have failed in this their proper
function.

TROPAEOLUM.--I observed T. tricolorum, T. azureum, T. pentaphyllum,
T. peregrinum, T. elegans, T. tuberosum, and a dwarf variety of, as I
believe, T. minus.

Tropaeolum tricolorum, var. grandiflorum.--The flexible shoots, which
first rise from the tubers, are as thin as fine twine. One such