32 
RIO DE JANEIRO 
CHAP. 
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, notwith¬ 
standing 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 spring¬ 
ing powers of this insect, which have not, as it appears to me, 
been properly described. 1 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 con¬ 
tinued, 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 pro¬ 
jecting 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 plea¬ 
sant 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 land¬ 
scape in the neighbourhood of Bahia almost takes its character 
1 Kirby’s Entomology, vol. ii. p. 317. 
