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
the superincumbent fluid were placed on four leaves, and when these
were looked at after 16 hrs., the tentacles and blades of all were
found strongly inflected. I infer from a remark by Gerhardt* that
legumin is present in peas “in combination with an alkali, forming an
incoagulable solution,” and this would mingle with boiling water. I may
mention, in relation to the above and following experiments, that
according to Schiff** certain forms of albumen
* Watts’ ‘Dictionary of Chemistry,’ vol. iii., p. 568.
** ‘Leçons sur la Phys. de la Digestion,’ tom. i, p. 379; tom. ii. pp.
154, 166, on legumin. [page 83]
exist which are not coagulated by boiling water, but are converted into
soluble peptones.
On three occasions chopped cabbage-leaves* were boiled in distilled
water for 1 hr. or for 1 1/4 hr.; and by decanting the decoction after
it had been allowed to rest, a pale dirty green fluid was obtained. The
usual-sized drops were placed on thirteen leaves. Their tentacles and
blades were inflected after 4 hrs. to a quite extraordinary degree.
Next day the protoplasm within the cells of the tentacles was found
aggregated in the most strongly marked manner. I also touched the
viscid secretion round the glands of several tentacles with minute
drops of the decoction on the head of a small pin, and they became well
inflected in a few minutes. The fluid proving so powerful, one part was
diluted with three of water, and drops were placed on the discs of five
leaves; and these next morning were so much acted on that their blades
were completely doubled over. We thus see that a decoction of
cabbage-leaves is nearly or quite as potent as an infusion of raw meat.