travelling round the walls of the cells. This current ceases to be
visible as soon as the contents are well aggregated; but it probably
still continues, though no longer visible, owing to all the granules in
the flowing layer having become united with the central masses. In all
these respects the filaments of Dionaea behave exactly like the
tentacles of Drosera.
Notwithstanding this similarity there is one remarkable difference. The
tentacles of Drosera, after their glands have been repeatedly touched,
or a particle of any kind has been placed on them, become inflected and
strongly aggregated. No such effect is produced by touching the
filaments of Dionaea; I compared, after an hour or two, some which had
been touched and some which had not, and others after twenty-five
hours, and there was no difference in the contents of the cells. The
leaves were kept open all the time by clips; so that the filaments were
not pressed against the opposite lobe.
Drops of water, or a thin broken stream, falling from a height on the
filaments, did not cause the blades to close; though these filaments
were afterwards proved to be highly sensitive. No doubt, as in the case
of Drosera, the plant is indifferent to the heaviest shower of rain.
Drops of a solution of a half an ounce of sugar to a fluid ounce of
water were repeatedly allowed to fall from a height on the filaments,
but produced no effect, unless they adhered to them. Again, I blew many
times through a fine pointed tube with my utmost force against the
filaments without any effect; such blowing being received [page 292]
with as much indifference as no doubt is a heavy gale of wind. We thus
see that the sensitiveness of the filaments is of a specialised nature,
being related to a momentary touch rather than to prolonged pressure;
and the touch must not be from fluids, such as air or water, but from
some solid object.
Although drops of water and of a moderately strong solution of sugar,
falling on the filaments, does not excite them, yet the immersion of a
leaf in pure water sometimes caused the lobes to close. One leaf was
left immersed for 1 hr. 10 m., and three other leaves for some minutes,
in water at temperatures varying between 59 and 65 (15 to 18 .3
Cent.) without any effect. One, however, of these four leaves, on being
gently withdrawn from the water, closed rather quickly. The three other
leaves were proved to be in good condition, as they closed when their
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