reached the centre. Although some of the tentacles began to move
moderately soon, they afterwards moved with extreme slowness. By next
morning, after 20 hrs., most of the tentacles on both leaves were
closely inflected, but not quite regularly. After 48 hrs. neither leaf
appeared injured, though the tentacles were still inflected; after 72
hrs. one was almost dead, whilst the other was re-expanding and
recovering.
Carbonic Acid. A plant was placed under a 122-oz. bell-glass filled
with this gas and standing over water; but I did not make sufficient
allowance for the absorption of the gas by the water, so that towards
the latter part of the experiment some air was drawn in. After an
exposure of 2 hrs. the plant was removed, and bits of raw meat placed
on the glands of three leaves. One of these leaves hung a little down,
and was at first partly and soon afterwards completely covered by the
water, which rose within the vessel as the gas was absorbed. On this
latter leaf the tentacles, to which meat had been given, became well
inflected in 2 m. 30 s., that is, at about the normal rate; so that
until I remembered that the leaf had been protected from the gas, and
might perhaps have absorbed oxygen from the water which was continually
drawn inwards, I falsely concluded that the carbonic acid had produced
no effect. On the other two leaves, the tentacles with meat behaved
very differently from those on the first leaf; two of them first began
to move slightly in 1 hr. 50 m., always reckoning from the time when
the meat was placed on the glands were plainly inflected in 2 hrs. 22
m. and in 3 hrs 22 m. reached the centre. Three other tentacles did not
begin to move until 2 hrs. 20 m. had elapsed, but reached the centre at
about the same time with the others, viz. in 3 hrs. 22 m.
This experiment was repeated several times with nearly the same
results, excepting that the interval before the tentacles began to move
varied a little. I will give only one other case. [page 222] A plant
was exposed in the same vessel to the gas for 45 m., and bits of meat
were then placed on four glands. But the tentacles did not move for 1
hr. 40 m.; after 2 hrs. 30 m. all four were well inflected, and after 3
hrs. reached the centre.
The following singular phenomenon sometimes, but by no means always,
occurred. A plant was immersed for 2 hrs., and bits of meat were then
placed on several glands. In the course of 13 m. all the submarginal
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