few minutes a slight motion of its feet was seen; after a couple of
hours, it was nearly as active as before the experiment; two hours
later, it was found dead.' The same effects, with slight variations,
were produced on other flies. With ether, cessation of motion was
almost instantaneous, followed, however, by revivification, except in
one instance: brief immersion in chloroform did not prevent revival,
but an exposure of eight minutes killed: camphor and turpentine were
both fatal: with attar of roses, musk, or iodine, no ill effect was
perceptible.

The experiments with prussic acid are worthy the attention of
entomologists, with whom it is often a matter of importance to kill an
insect with the least possible amount of injury. In these instances,
the plan pursued was to charge a small tube with the acid, and place
it inside that containing the insects. The vapour of 1-16th of a grain
was sufficient to destroy bees and flies; and that of seven grains
proved fatal to large beetles, and the largest kind of bees. Although
as yet the investigation has taken but a limited range, it will be
seen that it opens a wide field of research: the next step will be to
group or class those agents which appear to have produced similar
effects. It is remarkable, as Dr Davy observes, 'that most of the
substances which, even in minute portions mixed with common air,
prevent the slow combustion of phosphorus, as indicated by its shining
in the dark, have the effect, on the insects on which they were tried,
of suspending animation.'

He says further: 'Some of the results may not be undeserving notice
for practical purposes--as those in the instances of sulphuretted
hydrogen, oil of turpentine, and camphor, in relation to the
destruction of parasitical insects, whether infesting plants or