Drosera capensis.—This species, a native of the Cape of Good Hope, was
sent to me by Dr. Hooker. The leaves are elongated, slightly concave
along the middle and taper towards the apex, [page 280] which is
bluntly pointed and reflexed. They rise from an almost woody axis, and
their greatest peculiarity consists in their foliaceous green
footstalks, which are almost as broad and even longer than the
gland-bearing blade. This species, therefore, probably draws more
nourishment from the air, and less from captured insects, than the
other species of the genus. Nevertheless, the tentacles are crowded
together on the disc, and are extremely numerous; those on the margins
being much longer than the central ones. All the glands have the same
form; their secretion is extremely viscid and acid.
The specimen which I examined had only just recovered from a weak state
of health. This may account for the tentacles moving very slowly when
particles of meat were placed on the glands, and perhaps for my never
succeeding in causing any movement by repeatedly touching them with a
needle. But with all the species of the genus this latter stimulus is
the least effective of any. Particles of glass, cork, and coal-cinders,
were placed on the glands of six tentacles; and one alone moved after
an interval of 2 hrs. 30 m. Nevertheless, two glands were extremely
sensitive to very small doses of the nitrate of ammonia, namely to
about 1/20 of a minim of a solution (one part to 5250 of water),
containing only 1/115200 of a grain (.000562 mg.) of the salt.
Fragments of flies were placed on two leaves near their tips, which
became incurved in 15 hrs. A fly was also placed in the middle of the
leaf; in a few hours the tentacles on each side embraced it, and in 8
hrs. the whole leaf directly beneath the fly was a little bent
transversely. By the next morning, after 23 hrs., the leaf was curled
so completely over that the apex rested on the upper end of the
footstalk. In no case did the sides of the leaves become inflected. A
crushed fly was placed on the foliaceous footstalk, but produced no
effect.
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