fact, that a bit of hard-boiled white of egg, first thoroughly dried,
then soaked for some minutes in water and rolled on blotting paper,
should yield in a few hours enough animal matter to the glands to cause
them to secrete, and afterwards the lobes to close. That the glands
have the power of absorption is likewise shown by the very different
lengths of time (as we shall presently see) during which the lobes
remain closed over insects and other bodies yielding soluble
nitrogenous matter, and over such as do not yield any. But there is
direct evidence of absorption in the condition of the glands which have
remained for some time in contact with animal matter. Thus bits of meat
and crushed insects were several times placed on glands, and these were
compared after some hours with other glands from distant parts of the
same leaf. The latter showed not a trace of aggregation, whereas those
which had been in contact with the animal matter were [page 300] well
aggregated. Aggregation may be seen to occur very quickly if a piece of
a leaf is immersed in a weak solution of carbonate of ammonia. Again,
small cubes of albumen and gelatine were left for eight days on a leaf,
which was then cut open. The whole surface was bathed with acid
secretion, and every cell in the many glands which were examined had
its contents aggregated in a beautiful manner into dark or pale purple,
or colourless globular masses of protoplasm. These underwent incessant
slow changes of forms; sometimes separating from one another and then
reuniting, exactly as in the cells of Drosera. Boiling water makes the
contents of the gland-cells white and opaque, but not so purely white
and porcelain-like as in the case of Drosera. How living insects, when
naturally caught, excite the glands to secrete so quickly as they do, I
know not; but I suppose that the great pressure to which they are
subjected forces a little excretion from either extremity of their
bodies, and we have seen that an extremely small amount of nitrogenous
matter is sufficient to excite the glands.
Before passing on to the subject of digestion, I may state that I
endeavoured to discover, with no success, the functions of the minute
octofid processes with which the leaves are studded. From facts
hereafter to be given in the chapters on Aldrovanda and Utricularia, it
seemed probable that they served to absorb decayed matter left by the
captured insects; but their position on the backs of the leaves and on
the footstalks rendered this almost impossible. Nevertheless, leaves
were immersed in a solution of one part of urea to 437 of water, and
after 24 hrs. the orange layer of protoplasm within the arms of these
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