Tentacles Incapable of Movement.—Many of the tall tentacles, with
insects adhering to them, were carefully observed; and fragments of
insects, bits of raw meat, albumen, &c., drops of a solution of two
salts of ammonia and of saliva, were placed on the glands of many
tentacles; but not a trace of movement could ever be detected. I also
repeatedly irritated the glands with a needle, and scratched and
pricked the blades, but neither the blade nor the tentacles became at
all inflected. We may therefore conclude that they are incapable of
movement.
On the Power of Absorption possessed by the Glands.—It has already been
indirectly shown that the glands on pedicels absorb animal matter; and
this is further shown by their changed colour, and by the aggregation
of their contents, after they have been left in contact with
nitrogenous substances or liquids. The following observations apply
both to the glands supported on [page 338] pedicels and to the minute
sessile ones. Before a gland has been in any way stimulated, the
exterior cells commonly contain only limpid purple fluid; the more
central ones including mulberry-like masses of purple granular matter.
A leaf was placed in a little solution of one part of carbonate of
ammonia to 146 of water (3 grs. to 1 oz.), and the glands were
instantly darkened and very soon became black; this change being due to
the strongly marked aggregation of their contents, more especially of
the inner cells. Another leaf was placed in a solution of the same
strength of nitrate of ammonia, and the glands were slightly darkened
in 25 m., more so in 50 m., and after 1 hr. 30 m. were of so dark a red
as to appear almost black. Other leaves were placed in a weak infusion
of raw meat and in human saliva, and the glands were much darkened in
25 m., and after 40 m. were so dark as almost to deserve to be called
black. Even immersion for a whole day in distilled water occasionally
induces some aggregation within the glands, so that they become of a
darker tint. In all these cases the glands are affected in exactly the
same manner as those of Drosera. Milk, however, which acts so
energetically on Drosera, seems rather less effective on Drosophyllum,
for the glands were only slightly darkened by an immersion of 1 hr. 20
m., but became decidedly darker after 3 hrs. Leaves which had been left
for 7 hrs. in an infusion of raw meat or in saliva were placed in the
solution of carbonate of ammonia, and the glands now became greenish;
whereas, if they had been first placed in the carbonate, they would
have become black. In this latter case, the ammonia probably combines
with the acid of the secretion, and therefore does not act on the
colouring matter; but when the glands are first subjected to an organic
[page 339] fluid, either the acid is consumed in the work of digestion
or the cell-walls are rendered more permeable, so that the undecomposed
carbonate enters and acts on the colouring matter. If a particle of the
Public-domain text, read in full here on John Shaqi.
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