A tentacle on an old leaf was next observed in the
same manner. In 15 m. after being placed under the microscope it had moved
about 1/1000 of an inch. During the next 7 ? h. it was looked at
repeatedly, and during this whole time it moved only another 1/1000 of an
inch; and this small movement may have been due to the settling of the damp
sand (on which the plant rested), though the sand had been firmly pressed
down. We may therefore conclude that the tentacles when old do not
circumnutate; yet this tentacle was so sensitive, that in 23 seconds after
its gland had been merely touched with a bit of raw meat, it began to curl
inwards. This fact is of some importance, as it apparently shows that the
inflection of the tentacles from the stimulus of absorbed animal matter
(and no doubt from that of contact with any object) is not due to modified
circumnutation.
(15.) Dionoea muscipula (Droseraceae).--It should be premised that the
leaves at an early stage of their development have the two lobes pressed
closely together. These are at first directed back towards the centre of
the plant; but they gradually rise up and soon stand at right angles to the
petiole, and ultimately in nearly a straight line with it.
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