of limpid fluid they now contained small aggregated masses of
protoplasm, which slowly and incessantly changed their forms. A similar
result followed from an immersion of only 15 minutes in a solution of
one part of carbonate of ammonia to 218 of water, and the adjoining
cells of the tentacles, on which the papillae were seated, now likewise
contained aggregated masses of protoplasm. We may therefore conclude
that when a leaf has closely clasped a captured insect in the manner
immediately to be described, the papillae, which project from the upper
surface of the leaf and of the tentacles, probably absorb some of the
animal matter dissolved in the secretion; but this cannot be the case
with the papillae on the backs of the leaves or on the petioles.]
* Nitschke has elaborately described and figured these papillae, Bot.
Zeitung, 1861, pp. 234, 253, 254. [page 9]
_Preliminary Sketch of the Action of the several Parts, and of the
Manner in which Insects are Captured._
If a small organic or inorganic object be placed on the glands in the
centre of a leaf, these transmit a motor impulse to the marginal
tentacles. The nearer ones are first affected and slowly bend towards
the centre, and then those farther off, until at last all become
closely inflected over the object. This takes place in from one hour to
four or five or more hours. The difference in the time required depends
on many circumstances; namely on the size of the object and on its
nature, that is, whether it contains soluble matter of the proper kind;
on the vigour and age of the leaf; whether it has lately been in
action; and, according to Nitschke,* on the temperature of the day, as
likewise seemed to me to be the case. A living insect is a more
efficient object than a dead one, as in struggling it presses against
the glands of many tentacles. An insect, such as a fly, with thin
integuments, through which animal matter in solution can readily pass
into the surrounding dense secretion, is more efficient in causing
prolonged inflection than an insect with a thick coat, such as a
beetle. The inflection of the tentacles takes place indifferently in
the light and darkness; and the plant is not subject to any nocturnal
movement of so-called sleep.
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