secreting. It is evident that this oil is highly exciting and poisonous
to Drosera.
Oil of Cloves. A mixture was made in the same manner as in the last
case, and three leaves were immersed in it. After 30 m. there was only
a trace of inflection which never increased. After 1 hr. 30 m. the
glands were pale, and after 6 hrs. white. No doubt the leaves were much
injured or killed.
Turpentine. Small drops placed on the discs of some leaves killed them,
as did likewise drops of creosote. A plant was left for 15 m. under a
12-oz. vessel, with its inner surface wetted with twelve drops of
turpentine; but no movement of the tentacles ensued. After 24 hrs. the
plant was dead.
Glycerine. Half-minims were placed on the discs of three leaves: in 2
hrs. some of the outer tentacles were irregularly inflected; and in 19
hrs. the leaves were flaccid and apparently dead; the glands which had
touched the glycerine were colourless. Minute drops (about 1/20 of a
minim) were applied to the glands of several tentacles, and in a few
minutes these moved and soon reached the centre. Similar drops of a
mixture of four dropped drops to 1 oz. of water were likewise applied
to several glands; but only a few of the tentacles moved, and these
very slowly and slightly. Half-minims of this same mixture placed on
the discs of some leaves caused, to my surprise, no inflection in the
course of 48 hrs. Bits of meat were then given them, and next day they
were well inflected; notwithstanding that some of the discal glands had
been rendered almost colourless. Two leaves were immersed in the same
mixture, but only for 4 hrs.; they were not inflected, and on being
afterwards left for 2 hrs. 30 m. in a solution (1 gr. to 1 oz.) of
carbonate of ammonia, their glands were blackened, their tentacles
inflected, and the protoplasm within their cells aggregated. It appears
[page 213] from these facts that a mixture of four drops of glycerine
to an ounce of water is not poisonous, and excites very little
inflection; but that pure glycerine is poisonous, and if applied in
very minute quantities to the glands of the outer tentacles causes
their inflection.
The Effects of Immersion in Water and in various Solutions on the
subsequent Action of Phosphate and Carbonate of Ammonia. We have seen
194