motor impulse to the outer tentacles; though these, when their own
glands absorb the acid, are strongly acted on.
Lactic Acid. Three leaves were immersed in ninety minims of one part to
437 of water. After 48 m. there was no inflection, but the surrounding
fluid was coloured pink; after 8 hrs. 30 m. one leaf alone was a little
inflected, and almost all the glands on all three leaves were of a very
pale colour. The leaves were then washed and placed in a solution (1
gr. to 20 oz.) of phosphate of ammonia; after about 16 hrs. there was
only a trace of inflection. They were left in the phosphate for 48
hrs., and remained in the same state, with almost all their glands
discoloured. The protoplasm within the cells was not aggregated, except
in a very few tentacles, the glands of which were not much discoloured.
I believe, therefore, that almost all the glands and tentacles had been
killed by the acid so suddenly that hardly any inflection was caused.
Four leaves were next immersed in 120 minims of a weaker solution, of
one part to 875 of water; after 2 hrs. 30 m. the surrounding fluid was
quite pink; the glands were pale, but [page 194] there was no
inflection; after 7 hrs. 30 m. two of the leaves showed some
inflection, and the glands were almost white; after 21 hrs. two of the
leaves were considerably inflected, and a third slightly; most of the
glands were white, the others dark red. After 45 hrs. one leaf had
almost every tentacle inflected; a second a large number; the third and
fourth very few; almost all the glands were white, excepting those on
the discs of two of the leaves, and many of these were very dark red.
The leaves appeared dead. Hence lactic acid acts in a very peculiar
manner, causing inflection at an extraordinarily slow rate, and being
highly poisonous. Immersion in even weaker solutions, viz. of one part
to 1312 and 1750 of water, apparently killed the leaves (the tentacles
after a time being bowed backwards), and rendered the glands white, but
caused no inflection.
Gallic, Tannic, Tartaric, and Citric Acids. One part to 437 of water.
Three or four leaves were immersed, each in thirty minims of these four
solutions, so that each leaf received 1/16 of a grain, or 4.048 mg. No
inflection was caused in 24 hrs., and the leaves did not appear at all
injured. Those which had been in the tannic and tartaric acids were
placed in a solution (1 gr. to 20 oz.) of phosphate of ammonia, but no
inflection ensued in 24 hrs. On the other hand, the four leaves which
had been in the citric acid, when treated with the phosphate, became
175