the weak solution, and on another, which had only two of its tentacles
inflected, drops of the solution as thick as milk were placed; and next
morning, after an interval of 16 hrs., both were found with all their
tentacles strongly inflected.]
Altogether I experimented on sixty-four leaves with the above
nitrogenous fluids, the five leaves tried only with the extremely weak
solution of isinglass not being included, nor the numerous trials
subsequently made, of which no exact account was kept. Of these
sixty-four leaves, sixty-three had their tentacles and often their
blades well inflected. The one which failed was probably too old and
torpid. But to obtain so large a proportion of successful cases, care
must be taken to select young and active leaves. Leaves in this
condition were chosen with equal care for the sixty-one trials with
non-nitrogenous fluids (water not included); and we have seen that not
one of these was in the least affected. We may therefore safely
conclude that in the sixty-four experiments with nitrogenous fluids the
inflection of the exterior tentacles was due to the absorption of [page
82] nitrogenous matter by the glands of the tentacles on the disc.
Some of the leaves which were not affected by the non-nitrogenous
fluids were, as above stated, immediately afterwards tested with bits
of meat, and were thus proved to be in an active condition. But in
addition to these trials, twenty-three of the leaves, with drops of
gum, syrup, or starch, still lying on their discs, which had produced
no effect in the course of between 24 hrs. and 48 hrs., were then
tested with drops of milk, urine, or albumen. Of the twenty-three
leaves thus treated, seventeen had their tentacles, and in some cases
their blades, well inflected; but their powers were somewhat impaired,
for the rate of movement was decidedly slower than when fresh leaves
were treated with these same nitrogenous fluids. This impairment, as
well as the insensibility of six of the leaves, may be attributed to
injury from exosmose, caused by the density of the fluids placed on
their discs.
[The results of a few other experiments with nitrogenous fluids may be
here conveniently given. Decoctions of some vegetables, known to be
rich in nitrogen, were made, and these acted like animal fluids. Thus,
a few green peas were boiled for some time in distilled water, and the
moderately thick decoction thus made was allowed to settle. Drops of
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