the operation. I therefore cut the glands off twenty-five tentacles, at
different times and on different leaves, and seventeen of these soon
became inflected, and afterwards re-expanded. The re-expansion
commenced in about [page 242] 8 hrs. or 9 hrs., and was completed in
from 22 hrs. to 30 hrs. from the time of inflection. After an interval
of a day or two, raw meat with saliva was placed on the discs of these
seventeen leaves, and when observed next day, seven of the headless
tentacles were inflected over the meat as closely as the uninjured ones
on the same leaves; and an eighth headless tentacle became inflected
after three additional days. The meat was removed from one of these
leaves, and the surface washed with a little stream of water, and after
three days the headless tentacle re-expanded for the second time. These
tentacles without glands were, however, in a different state from those
provided with glands and which had absorbed matter from the meat, for
the protoplasm within the cells of the former had undergone far less
aggregation. From these experiments with headless tentacles it is
certain that the glands do not, as far as the motor impulse is
concerned, act in a reflex manner like the nerve-ganglia of animals.
But there is another action, namely that of aggregation, which in
certain cases may be called reflex, and it is the only known instance
in the vegetable kingdom. We should bear in mind that the process does
not depend on the previous bending of the tentacles, as we clearly see
when leaves are immersed in certain strong solutions. Nor does it
depend on increased secretion from the glands, and this is shown by
several facts, more especially by the papillae, which do not secrete,
yet undergoing aggregation, if given carbonate of ammonia or an
infusion of raw meat. When a gland is directly stimulated in any way,
as by the pressure of a minute particle of glass, the protoplasm within
the cells of the gland first becomes aggregated, then that in the cells
immediately beneath the gland, and so lower and lower down the
tentacles to their bases; [page 243] that is, if the stimulus has been
sufficient and not injurious. Now, when the glands of the disc are
excited, the exterior tentacles are affected in exactly the same
manner: the aggregation always commences in their glands, though these
have not been directly excited, but have only received some influence
from the disc, as shown by their increased acid secretion. The
protoplasm within the cells immediately beneath the glands are next
affected, and so downwards from cell to cell to the bases of the
tentacles. This process apparently deserves to be called a reflex
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