that the area of both surfaces was 78.57 square inches. Thus the plant
(excluding the flower-stems) must have borne the astonishing number of
2,568,099 glandular hairs. The hairs were counted late in the autumn,
and by the following spring (May) the leaves of some other plants of
the same lot were found to be from one-third to one-fourth broader and
longer than they were before; so that no doubt the glandular hairs had
increased in number, and probably now much exceeded three millions.
[page 356]
movement makes up for the loss of viscid secretion. In every case it is
some part of the leaf which moves. In Aldrovanda it appears to be the
basal parts alone which contract and carry with them the broad, thin
margins of the lobes. In Dionaea the whole lobe, with the exception of
the marginal prolongations or spikes, curves inwards, though the chief
seat of movement is near the midrib. In Drosera the chief seat is in
the lower part of the tentacles, which, homologically, may be
considered as prolongations of the leaf; but the whole blade often
curls inwards, converting the leaf into a temporary stomach.
There can hardly be a doubt that all the plants belonging to these six
genera have the power of dissolving animal matter by the aid of their
secretion, which contains an acid, together with a ferment almost
identical in nature with pepsin; and that they afterwards absorb the
matter thus digested. This is certainly the case with Drosera,
Drosophyllum, and Dionaea; almost certainly with Aldrovanda; and, from
analogy, very probable with Roridula and Byblis. We can thus understand
how it is that the three first-named genera are provided with such
small roots, and that Aldrovanda is quite rootless; about the roots of
the two other genera nothing is known. It is, no doubt, a surprising
fact that a whole group of plants (and, as we shall presently see, some
other plants not allied to the Droseraceae) should subsist partly by
digesting animal matter, and partly by decomposing carbonic acid,
instead of exclusively by this latter means, together with the
absorption of matter from the soil by the aid of roots. We have,
however, an equally anomalous case in the animal kingdom; the
rhizocephalous crustaceans do not feed like other animals by their
mouths, for they are destitute of an [page 357] alimentary canal; but
they live by absorbing through root-like processes the juices of the
animals on which they are parasitic.*
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