energetically than any other substance), of paper, dried moss, and of
the quill of a pen were placed on several leaves, and they were all
embraced equally well in about 2 hrs. On other occasions the
above-named substances, or more commonly particles of glass,
coal-cinder (taken from the fire), stone, gold-leaf, dried grass, cork,
blotting-paper, cotton-wool, and hair rolled up into little balls, were
used, and these substances, though they were sometimes well embraced,
often caused no movement whatever in the outer tentacles, or an
extremely slight and slow movement. Yet these same leaves were proved
to be in an active condition, as they were excited to move by
substances yielding soluble nitrogenous matter, such as bits of raw or
roast meat, the yolk or white of boiled eggs, fragments of insects of
all orders, spiders, &c. I will give only two instances. Minute flies
were placed on the discs of several leaves, and on others balls of
paper, bits of moss and quill of about the same size as the flies, and
the latter were well embraced in a few hours; whereas after 25 hrs.
only a very few tentacles were inflected over the other objects. The
bits of paper, moss, and quill were then removed from these leaves, and
bits of raw meat placed on them; and now all the tentacles were soon
energetically inflected.

Again, particles of coal-cinder (weighing rather more than the flies
used in the last experiment) were placed on the centres of three
leaves: after an interval of 19 hrs. one of the particles was tolerably
well embraced; [page 23] a second by a very few tentacles; and a third
by none. I then removed the particles from the two latter leaves, and
put on them recently killed flies. These were fairly well embraced in 7
1/2 hrs. and thoroughly after 20 1/2 hrs.; the tentacles remaining
inflected for many subsequent days. On the other hand, the one leaf
which had in the course of 19 hrs. embraced the bit of cinder