On The Muddy And Wet
Gravel-Walks I Found The Larvae Of This Lampyris In Great
Numbers:
They resembled in general form the female of the
English glowworm.
These larvae possessed but feeble luminous
powers; very differently from their parents, on the
slightest touch they feigned death and ceased to shine; nor
did irritation excite any fresh display. I kept several of
them alive for some time: their tails are very singular organs,
for they act, by a well-fitted contrivance, as suckers or organs
of attachment, and likewise as reservoirs for saliva, or some
such fluid. I repeatedly fed them on raw meat; and I invariably
observed, that every now and then the extremity
of the tail was applied to the mouth, and a drop of fluid
exuded on the meat, which was then in the act of being consumed.
The tail, notwithstanding so much practice, does not
seem to be able to find its way to the mouth; at least the neck
was always touched first, and apparently as a guide.
When we were at Bahia, an elater or beetle (Pyrophorus
luminosus, Illig.) seemed the most common luminous insect.
The light in this case was also rendered more brilliant by
irritation. I amused myself one day by observing the springing
powers of this insect, which have not, as it appears to
me, been properly described. [5] The elater, when placed on
its back and preparing to spring, moved its head and thorax
backwards, so that the pectoral spine was drawn out, and
rested on the edge of its sheath. The same backward movement
being continued, the spine, by the full action of the
muscles, was bent like a spring; and the insect at this moment
rested on the extremity of its head and wing-cases.
The effort being suddenly relaxed, the head and thorax flew
up, and in consequence, the base of the wing-cases struck
the supporting surface with such force, that the insect by
the reaction was jerked upwards to the height of one or
two inches. The projecting points of the thorax, and the
sheath of the spine, served to steady the whole body during
the spring. In the descriptions which I have read, sufficient
stress does not appear to have been laid on the elasticity of
the spine: so sudden a spring could not be the result of simple
muscular contraction, without the aid of some mechanical
contrivance.
On several occasions I enjoyed some short but most pleasant
excursions in the neighbouring country. One day I went
to the Botanic Garden, where many plants, well known for
their great utility, might be seen growing. The leaves of the
camphor, pepper, cinnamon, and clove trees were delightfully
aromatic; and the bread-fruit, the jaca, and the mango,
vied with each other in the magnificence of their foliage.
The landscape in the neighbourhood of Bahia almost takes
its character from the two latter trees. Before seeing them,
I had no idea that any trees could cast so black a shade on
the ground.
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