placed began to open, and on the third day was much more open than the
opposite end where the albumen had lain.
Lastly, large drops of a solution of one part of carbonate of ammonia
to 146 of water were placed on some leaves, but no immediate movement
ensued. I did not then know of the slow movement caused by animal
matter, otherwise I should have observed the leaves for a longer time,
and they would probably have been found closed, though the solution
(judging from Drosera) was, perhaps, too strong.
From the foregoing cases it is certain that bits of meat and albumen,
if at all damp, excite not only the glands to secrete, but the lobes to
close. This movement is widely different from the rapid closure caused
by one of the filaments being touched. We shall see its importance when
we treat of the manner in which insects are captured. There is a great
contrast between Drosera and Dionaea in the effects produced by
mechanical irritation on the one hand, and the absorption of animal
matter on the other. Particles of glass placed on the glands of the
exterior tentacles of Drosera excite movement within nearly the same
time, as do particles of meat, the latter being rather the most
efficient; but when the glands of the disc have bits of meat given
them, they transmit a motor impulse to the exterior tentacles much more
quickly than do these glands when bearing inorganic particles, or when
irritated by repeated touches. On the other hand, with Dionaea,
touching the filaments excites incomparably quicker movement than the
absorption of animal matter by the glands. Nevertheless, in [page 299]
certain cases, this latter stimulus is the more powerful of the two. On
three occasions leaves were found which from some cause were torpid, so
that their lobes closed only slightly, however much their filaments
were irritated; but on inserting crushed insects between the lobes,
they became in a day closely shut.
The facts just given plainly show that the glands have the power of
absorption, for otherwise it is impossible that the leaves should be so
differently affected by non-nitrogenous and nitrogenous bodies, and
between these latter in a dry and damp condition. It is surprising how
slightly damp a bit of meat or albumen need be in order to excite
secretion and afterwards slow movement, and equally surprising how
minute a quantity of animal matter, when absorbed, suffices to produce
these two effects. It seems hardly credible, and yet it is certainly a
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