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.

If the glands on the disc are repeatedly touched or brushed, although
no object is left on them, the marginal tentacles curve inwards. So
again, if drops of various fluids, for instance of saliva or of a
solution of any salt of ammonia, are placed on the central glands, the
same result quickly follows, sometimes in under half an hour.

* 'Bot. Zeitung,' 1860, p. 246. [page 10]

The tentacles in the act of inflection sweep through a wide space; thus
a marginal tentacle, extended in the same plane with the blade, moves
through an angle of 180o; and I have seen the much reflected tentacles
of a leaf which stood upright move through an angle of not less than
270o. The bending part is almost confined to a short space near the