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
judging by the sound, and comparing them with a string tuned in unison
thereto, consist of many hundreds, if not thousands, in a second of
time. The powers of the governing faculty of the insect, and the
vivacity of its sensations, whereby every organ is stimulated to act
with so much velocity and regularity, surpass our present comprehension.
[58] Hooke’s Micrographia, p. 172.
PEDES THE FEET, AND LEGS OF INSECTS.
These are admirably adapted for their intended service, to give the most
convenient and proper motion, and, from the variety in their
construction, their various articulations, &c. furnish the microscopic
observer with an abundance of curious and interesting objects: the most
general number is six; many of the class aptera have eight, as the
spider; the crab has ten; the oniscus fourteen; the julus has from
seventy to one-hundred and twenty on each side. The legs of those
insects that have not more than ten, are affixed to the trunk; while
those that exceed that number, have part fixed to the trunk, the rest to
the abdomen.
The legs of insects are generally divided into four parts. The first,
which is usually the largest, is called the femur; the second, or tibia,
is joined to the former, and is commonly of the same size throughout,
and longer than the femur; this is followed by the third part, which is
distinguished by the name of tarsus, or foot; it is composed of several
joints, the one articulated to the other, the number of rings varying in
different insects; the tarsus is terminated by the unguis, or claw.
The writers on natural history, in order to render their descriptions
clear and accurate, have given several names to the legs of insects,
from the nature of the motions produced by them. Thus cursorii, from
that of running; these are the most numerous. The saltatorii, those that
are used for leaping; the thighs of these are remarkably large, by which
means they possess considerable strength and power to leap to great
distances. The natatorii, those that serve as oars for swimming; the
feet of these are flat and edged with hairs, possessing a proper surface
to strike against the water, as in the dytiscus, notonecta, &c. Such
feet as have no claws are termed mutici. The chelæ, or claws, are an
enlargement of the extremity of the fore feet, each of which is
furnished with two lesser claws, which act like a thumb and finger, as
in the crab. The under part of the feet in some insects is covered with
a kind of brush or sponge, by which they are enabled to walk with ease,
on the most polished substances, and in situations from which it would
seem they must necessarily fall.
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