freely.
We have seen that inorganic and non-nitrogenous objects placed on the
leaves do not excite any movement; but nitrogenous bodies, if in the
least degree damp, cause after several hours the lobes to close slowly.
Thus bits of quite dry meat and gelatine were placed at opposite ends
of the same leaf, and in the course of 24 hrs. excited neither
secretion nor movement. They were then dipped in water, their surfaces
dried on blotting paper, and replaced on the same [page 297] leaf, the
plant being now covered with a bell-glass. After 24 hrs. the damp meat
had excited some acid secretion, and the lobes at this end of the leaf
were almost shut. At the other end, where the damp gelatine lay, the
leaf was still quite open, nor had any secretion been excited; so that,
as with Drosera, gelatine is not nearly so exciting a substance as
meat. The secretion beneath the meat was tested by pushing a strip of
litmus paper under it (the filaments not being touched), and this
slight stimulus caused the leaf to shut. On the eleventh day it
reopened; but the end where the gelatine lay, expanded several hours
before the opposite end with the meat.
A second bit of roast meat, which appeared dry, though it had not been
purposely dried, was left for 24 hrs. on a leaf, caused neither
movement nor secretion. The plant in its pot was now covered with a
bell-glass, and the meat absorbed some moisture from the air; this
sufficed to excite acid secretion, and by the next morning the leaf was
closely shut. A third bit of meat, dried so as to be quite brittle, was
placed on a leaf under a bell-glass, and this also became in 24 hrs.
slightly damp, and excited some acid secretion, but no movement.
A rather large piece of perfectly dry albumen was left at one end of a
leaf for 24 hrs. without any effect. It was then soaked for a few
minutes in water, rolled about on blotting paper, and replaced on the
leaf; in 9 hrs. some slightly acid secretion was excited, and in 24
hrs. this end of the leaf was partially closed. The bit of albumen,
which was now surrounded by much secretion, was gently removed, and
although no filament was touched, the lobes closed. In this and the
previous case, it appears that the absorption of animal matter by the
glands renders [page 298] the surface of the leaf much more sensitive
to a touch than it is in its ordinary state; and this is a curious
fact. Two days afterwards the end of the leaf where nothing had been
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