the midrib of the fully expanded leaf was .35 of an inch (8.89 mm.); so
that the bit had been pushed inwards and across nearly one-third of its
semi-diameter.
Experiment 8. Cubes of sponge, soaked in a strong infusion of raw meat,
were placed in close contact with the incurved edges of two leaves, an
older and younger one. The distance from the edges to the midribs was
carefully measured. After 1 hr. 17 m. there appeared to be a trace of
incurvation. After 2 hrs. 17 m. both leaves were plainly inflected; the
distance between the edges and midribs being now only half what it was
at first. The incurvation increased slightly during the next 4 1/2
hrs., but remained nearly the same for the next 17 hrs. 30 m. In 35
hrs. from the time when the sponges were placed on the leaves, the
margins were a little unfolded to a greater degree in the younger than
in the older leaf. The latter was not quite unfolded until the third
day, and now both bits of sponge were left at the distance of .1 of an
inch (2.54 mm.) from the edges; or about a quarter of the distance
between the edge and midrib. A third bit of sponge adhered to the edge,
and, as the margin unfolded, was dragged backwards, into its original
position. [page 374]
Experiment 9. A chain of fibres of roast meat, as thin as bristles and
moistened with saliva, were placed down one whole side, close to the
narrow, naturally incurved edge of a leaf. In 3 hrs. this side was
greatly incurved along its whole length, and after 8 hrs. formed a
cylinder, about 1/20 of an inch (1.27 mm) in diameter, quite concealing
the meat. This cylinder remained closed for 32 hrs., but after 48 hrs.
was half unfolded, and in 72 hrs. was as open as the opposite margin
where no meat had been placed. As the thin fibres of meat were
completely overlapped by the margin, they were not pushed at all
inwards, across the blade.
Experiment 10. Six cabbage seeds, soaked for a night in water, were
placed in a row close to the narrow incurved edge of a leaf. We shall
hereafter see that these seeds yield soluble matter to the glands. In 2
hrs. 25 m. the margin was decidedly inflected; in 4 hrs. it extended
over the seeds for about half their breadth, and in 7 hrs. over
three-fourths of their breadth, forming a cylinder not quite closed
along the inner side, and about .7 of an inch (1.778 mm.) in diameter.
After 24 hrs. the inflection had not increased, perhaps had decreased.
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