The central glands of a leaf were irritated with a small stiff
camel-hair brush, and in 70 m. (minutes) several of the outer tentacles
were inflected; in 5 hrs. (hours) all the sub-marginal tentacles were
inflected; next morning after an interval of about 22 hrs. they were
fully re-expanded. In all the following cases the period is reckoned
from the time of first irritation. Another leaf treated in the same
manner had a few tentacles inflected in 20 m.; in 4 hrs. all the
submarginal and some of the extreme marginal tentacles, as well as the
edge of the leaf itself, were inflected; in 17 hrs. they had recovered
their proper, expanded position. I then put a dead fly in the centre of
the last-mentioned leaf, and next morning it was closely clasped; five
days afterwards the leaf re-expanded, and the tentacles, with their
glands surrounded by secretion, were ready to act again.
Particles of meat, dead flies, bits of paper, wood, dried moss, sponge,
cinders, glass, &c., were repeatedly [page 21] placed on leaves, and
these objects were well embraced in various periods from one hr. to as
long as 24 hrs., and set free again, with the leaf fully re-expanded,
in from one or two, to seven or even ten days, according to the nature
of the object. On a leaf which had naturally caught two flies, and
therefore had already closed and reopened either once or more probably
twice, I put a fresh fly: in 7 hrs. it was moderately, and in 21 hrs.
thoroughly well, clasped, with the edges of the leaf inflected. In two
days and a half the leaf had nearly re-expanded; as the exciting object
was an insect, this unusually short period of inflection was, no doubt,
due to the leaf having recently been in action. Allowing this same leaf
to rest for only a single day, I put on another fly, and it again
closed, but now very slowly; nevertheless, in less than two days it
succeeded in thoroughly clasping the fly.
When a small object is placed on the glands of the disc, on one side of
a leaf, as near as possible to its circumference, the tentacles on this
side are first affected, those on the opposite side much later, or, as
often occurred, not at all. This was repeatedly proved by trials with
bits of meat; but I will here give only the case of a minute fly,
naturally caught and still alive, which I found adhering by its
delicate feet to the glands on the extreme left side of the central
disc. The marginal tentacles on this side closed inwards and killed the
fly, and after a time the edge of the leaf on this side also became
inflected, and thus remained for several days, whilst neither the
tentacles nor the edge on the opposite side were in the least affected.