Essays on the Microscope: Containing a Practical Description of the Most Improved Microscopes, a General History of Insects, etc., etc.Adams, George
Science
Essays on the Microscope: Containing a Practical Description of the Most Improved Microscopes, a General History of Insects, etc., etc.
Adams, George
Insects -- Early works to 1800; Microscopy -- Early works to 1800
insects require variety in the mode of suspension; some fix themselves
in an horizontal position, by a girdle which they tie round their body;
this girdle appears to the naked eye as a single thread; when examined
with the microscope, it will be found to be an assemblage of fine
threads, lying close to each other, so fixed as to support the
caterpillar, and yet leave it in full freedom to effect the changes.
Like the preceding kind, it fixes the girdle to the branch of a tree; in
this situation it remains for some time motionless, and then begins to
bend, move, and agitate its body in a very singular manner, till it has
opened the exterior covering, which it pushes off and removes much in
the same manner as we have described in the preceding article, and yet
with such dexterity, that the pupa remains suspended by the same girdle.
OF THE IMAGO OR FLY STATE OF INSECTS.
As soon as the moth acquires sufficient strength to break the bonds
which surround it, and of which it is informed by its internal
sensations, it makes a powerful effort to escape from its prison, and
view the world with new-formed eyes. The moth frees itself from the pupa
with much greater ease than the pupa from the caterpillar; for the case
of the pupa becomes so dry, when the moth is near the time of throwing
off its covering, that it will break to pieces if it be only gently
pressed between the fingers; and very few of the parts will be found, on
examination, to adhere to the body. Hence, when the insect has acquired
a proper degree of solidity, it does not require any great exertion to
split the membrane which covers it. A small degree of motion, or a
little inflation of the body, is sufficient for this purpose; these
motions reiterated a few times, enlarge the hole, and afford the moth
room to escape from its confinement. The opening through which they pass
is always at the same part of the skin, a little above the trunk,
between the wings, and a small piece which covers the head; the
different fissures are generally made in the same direction. If the
outer case be opened, it is easy to discover the efforts the insect
makes to emancipate itself from its shell; when the operation begins,
there seems to be a violent agitation in the humours contained in the
little animal; the fluids seem to be driven with rapidity through all
the vessels, and it is seen to agitate its legs, &c. as it were
struggling to get free; these efforts soon break its brittle skin. The
loosening the exterior bands of the pupa is not the only difficulty many
moths have to encounter with; it has often also to pierce the cone or
case in which it has been inclosed, and that at a time when its members
are very feeble, when it is no longer furnished with strong jaws to
pierce and cut its way through; but by the regular laws of divine order,
means are furnished to every creature of attaining the end for which it
was produced: thus, in the present case, some of these insects are
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