the helix of the human ear, to the breadth of 1/10 of an inch, so as to
lie partly over the row of flies (fig. 15). The glands on which the
flies rested, as well as those on the over-lapping margin which had
been brought into contact with the flies, were all secreting copiously.
FIG. 15. (Pinguicula vulgaris.) Outline of leaf with left margin
inflected over a row of small flies.
Experiment 2. A row of flies was placed on one margin of a rather old
leaf, which lay flat on the ground; and in this case the margin, after
the same interval as before, namely 15 hrs., had only just begun to
curl inwards; but so much secretion had been poured forth that the
spoon-shaped tip of the leaf was filled with it.
Experiment 3. Fragments of a large fly were placed close to the apex of
a vigorous leaf, as well as along half one margin. [page 372] After 4
hrs. 20 m. there was decided incurvation, which increased a little
during the afternoon, but was in the same state on the following
morning. Near the apex both margins were inwardly curved. I have never
seen a case of the apex itself being in the least curved towards the
base of the leaf. After 48 hrs. (always reckoning from the time when
the flies were placed on the leaf) the margin had everywhere begun to
unfold.
Experiment 4. A large fragment of a fly was placed on a leaf, in a
medial line, a little beneath the apex. Both lateral margins were
perceptibly incurved in 3 hrs., and after 4 hrs. 20 m. to such a degree
that the fragment was clasped by both margins. After 24 hrs. the two
infolded edges near the apex (for the lower part of the leaf was not at
all affected) were measured and found to be .11 of an inch (2.795 mm.)
apart. The fly was now removed, and a stream of water poured over the
leaf so as to wash the surface; and after 24 hrs. the margins were .25
of an inch (6.349 mm.) apart, so that they were largely unfolded. After
an additional 24 hrs. they were completely unfolded. Another fly was
now put on the same spot to see whether this leaf, on which the first
fly had been left 24 hrs., would move again; after 10 hrs. there was a
trace of incurvation, but this did not increase during the next 24 hrs.
A bit of meat was also placed on the margin of a leaf, which four days
previously had become strongly incurved over a fragment of a fly and
had afterwards re-expanded; but the meat did not cause even a trace of
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