The same result followed from the immersion of a whole branch for
nearly three days in a solution of one part of the carbonate to 1750 of
water. The grains of chlorophyll, also, in the cells of the leaves on
this branch became in many places aggregated into little green masses,
which were often connected together by the finest threads.
On the Absorption of certain Fluids by the Glands on the Valve and
Collar. The glands round the orifices of bladders which are still
young, or which have been [page 417] long kept in moderately pure
water, are colourless; and their primordial utricles are only slightly
or hardly at all granular. But in the greater number of plants in a
state of nature and we must remember that they generally grow in very
foul water and with plants kept in an aquarium in foul water, most of
the glands were of a pale brownish tint; their primordial utricles were
more or less shrunk, sometimes ruptured, with their contents often
coarsely granular or aggregated into little masses. That this state of
the glands is due to their having absorbed matter from the surrounding
water, I cannot doubt; for, as we shall immediately see, nearly the
same results follow from their immersion for a few hours in various
solutions. Nor is it probable that this absorption is useless, seeing
that it is almost universal with plants growing in a state of nature,
excepting when the water is remarkably pure.
The pedicels of the glands which are situated close to the slit-like
orifice, both those on the valve and on the collar, are short; whereas
the pedicels of the more distant glands are much elongated and project
inwards. The glands are thus well placed so to be washed by any fluid
coming out of the bladder through the orifice. The valve fits so
closely, judging from the result of immersing uninjured bladders in
various solutions, that it is doubtful whether any putrid fluid
habitually passes outwards. But we must remember that a bladder
generally captures several animals; and that each time a fresh animal
enters, a puff of foul water must pass out and bathe the glands.
Moreover, I have repeatedly found that, by gently pressing bladders
which contained air, minute bubbles were driven out through the
orifice; and if a bladder is laid on blotting paper and gently pressed,
water oozes out. [page 418] In this latter case, as soon as the
pressure is relaxed, air is drawn in, and the bladder recovers its
proper form. If it is now placed under water and again gently pressed,
minute bubbles issue from the orifice and nowhere else, showing that
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