they were considerably inflected, with the contents of their cells
aggregated, showing that the phosphate had acted, though not to the
full and ordinary degree.
Acetic Acid. Four leaves were immersed together in 120 minims of one
part to 437 of water. In 1 hr. 20 m. the tentacles of all four and the
blades of two were greatly inflected. After 8 hrs. the leaves had
become flaccid, but still remained closely inflected, the surrounding
fluid being coloured pink. They were then washed and placed in water;
next morning they were still inflected and of a very dark red colour,
but with their glands colourless. After another day they were
dingy-coloured, and [page 192] evidently dead. This acid is far more
powerful than formic, and is highly poisonous. Half-minim drops of a
stronger mixture (viz. one part by measure to 320 of water) were placed
on the discs of five leaves; none of the exterior tentacles, only those
on the borders of the disc which actually absorbed the acid, became
inflected. Probably the dose was too strong and paralysed the leaves,
for drops of a weaker mixture caused much inflection; nevertheless the
leaves all died after two days.
Propionic Acid. Three leaves were immersed in ninety minims of a
mixture of one part to 437 of water; in 1 hr. 50 m. there was no
inflection; but after 3 hrs. 40 m. one leaf was greatly inflected, and
the other two slightly. The inflection continued to increase, so that
in 8 hrs. all three leaves were closely inflected. Next morning, after
20 hrs., most of the glands were very pale, but some few were almost
black. No mucus had been secreted, and the surrounding fluid was only
just perceptibly tinted of a pale pink. After 46 hrs. the leaves became
slightly flaccid and were evidently killed, as was afterwards proved to
be the case by keeping them in water. The protoplasm in the closely
inflected tentacles was not in the least aggregated, but towards their
bases it was collected in little brownish masses at the bottoms of the
cells. This protoplasm was dead, for on leaving the leaf in a solution
of carbonate of ammonia, no aggregation ensued. Propionic acid is
highly poisonous to Drosera, like its ally acetic acid, but induces
inflection at a much slower rate.
Oleic Acid (given me by Prof. Frankland). Three leaves were immersed in
this acid; some inflection was almost immediately caused, which
increased slightly, but then ceased, and the leaves seemed killed. Next
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