tentacles.
The parent form of Dionaea and Aldrovanda seems to have been closely
allied to Drosera, and to have had rounded leaves, supported on
distinct footstalks, and furnished with tentacles all round the
circumference, with other tentacles and sessile glands on the upper
surface. I think so because the marginal spikes of Dionaea apparently
represent the extreme marginal tentacles of Drosera, the six (sometimes
eight) sensitive filaments on the upper surface, as well as the more
numerous ones in Aldrovanda, representing the central [page 361]
tentacles of Drosera, with their glands aborted, but their
sensitiveness retained. Under this point of view we should bear in mind
that the summits of the tentacles of Drosera, close beneath the glands,
are sensitive.
The three most remarkable characters possessed by the several members
of the Droseraceae consist in the leaves of some having the power of
movement when excited, in their glands secreting a fluid which digests
animal matter, and in their absorption of the digested matter. Can any
light be thrown on the steps by which these remarkable powers were
gradually acquired?
As the walls of the cells are necessarily permeable to fluids, in order
to allow the glands to secrete, it is not surprising that they should
readily allow fluids to pass inwards; and this inward passage would
deserve to be called an act of absorption, if the fluids combined with
the contents of the glands. Judging from the evidence above given, the
secreting glands of many other plants can absorb salts of ammonia, of
which they must receive small quantities from the rain. This is the
case with two species of Saxifraga, and the glands of one of them
apparently absorb matter from captured insects, and certainly from an
infusion of raw meat. There is, therefore, nothing anomalous in the
Droseraceae having acquired the power of absorption in a much more
highly developed degree.
It is a far more remarkable problem how the members of this family, and
Pinguicula, and, as Dr. Hooker has recently shown, Nepenthes, could all
have acquired the power of secreting a fluid which dissolves or digests
animal matter. The six genera of the Droseraceae very probably
inherited this power from a common progenitor, but this cannot apply to
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