The Climate, During The Months Of May And June, Or The
Beginning Of Winter, Was Delightful.
The mean temperature,
from observations taken at nine o'clock, both morning
and evening, was only 72 degs.
It often rained heavily, but
the drying southerly winds soon again rendered the walks
pleasant. One morning, in the course of six hours, 1.6 inches
of rain fell. As this storm passed over the forests which
surround the Corcovado, the sound produced by the drops
pattering on the countless multitude of leaves was very
remarkable, it could be heard at the distance of a quarter of
a mile, and was like the rushing of a great body of water.
After the hotter days, it was delicious to sit quietly in the
garden and watch the evening pass into night. Nature, in
these climes, chooses her vocalists from more humble performers
than in Europe. A small frog, of the genus Hyla,
sits on a blade of grass about an inch above the surface of
the water, and sends forth a pleasing chirp: when several
are together they sing in harmony on different notes. I had
some difficulty in catching a specimen of this frog. The
genus Hyla has its toes terminated by small suckers; and I
found this animal could crawl up a pane of glass, when
placed absolutely perpendicular. Various cicidae and crickets,
at the same time, keep up a ceaseless shrill cry, but which,
softened by the distance, is not unpleasant. Every evening
after dark this great concert commenced; and often have I
sat listening to it, until my attention has been drawn away
by some curious passing insect.
At these times the fireflies are seen flitting about from
hedge to hedge. On a dark night the light can be seen at
about two hundred paces distant. It is remarkable that in
all the different kinds of glowworms, shining elaters, and
various marine animals (such as the crustacea, medusae,
nereidae, a coralline of the genus Clytia, and Pyrosma),
which I have observed, the light has been of a well-marked
green colour. All the fireflies, which I caught here, belonged
to the Lampyridae (in which family the English glowworm
is included), and the greater number of specimens were of
Lampyris occidentalis. [4] I found that this insect emitted
the most brilliant flashes when irritated: in the intervals,
the abdominal rings were obscured. The flash was almost
co-instantaneous in the two rings, but it was just perceptible
first in the anterior one. The shining matter was fluid and
very adhesive: little spots, where the skin had been torn,
continued bright with a slight scintillation, whilst the
uninjured parts were obscured. When the insect was decapitated
the rings remained uninterruptedly bright, but not so brilliant
as before: local irritation with a needle always increased
the vividness of the light. The rings in one instance retained
their luminous property nearly twenty-four hours after the
death of the insect. From these facts it would appear probable,
that the animal has only the power of concealing or
extinguishing the light for short intervals, and that at other
times the display is involuntary.
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