INS 
parliament, chiefly from motives of deli- 
cacy. 
INSCRIBED, in geometry. A figure 
is said to be inscribed in another, when all 
its angles touch the sides or planes of the 
other figure. 
INSCRIPTION, a title or writing carv- 
ed, engraved, or affixed to any thing, to 
give a more distinct knowledge of it, or to 
transmit some important truth to posterity. 
The inscriptions mentioned by Herodotus 
and Diodorus Siculus, sufficiently shew that 
this was the first method of conveying in- 
struction to mankind, and transmitting the 
knowledge of history and sciences to poste- 
rity ; thus the ancients engraved upon pil- 
lars both the principles of sciences, and the 
history of the world. Pisistratus carved 
precepts of husbandry on pillars of stone ; 
and the treaties of confederacy between 
the Romans and Jews were engraved on 
plates of brass. Hence, antiquarians have 
been very curious in examining the inscrip- 
tions on ancient ruins, coins, medals, &c. 
INSECTS, in natural history. We have, 
under the article Entomology, given an 
account of the Linnajan system of this de- 
partment of natural history. We shall, in 
this place, enumerate some of those circum- 
stances which form the line of distinction 
between insects and other animals. In- 
sects are not furnished with red blood, but 
instead of it their vessels contain a trans- 
parent lymph. This may serve to distin- 
guish them from the superior animals, but 
it is common to them with many of the in- 
ferior; though Cuvier has lately demon- 
strated the existence of a kind of red blood 
in some of the vermes. They are destitute 
of internal hones; but, in place of them, 
are furnished with a hard external covering, 
to which the muscles are attached, which 
serves them both for skin and bones ; they 
are likewise without a spine formed of ver- 
tebrae, which is found in all the superior 
classes of animals. They are furnished 
with articulated legs, six or more; this cir- 
cumstance distinguishes them from ail other 
animals destitute of a spine formed of ver- 
tebrae. A very great number of insects un- 
dergo a metamorphosis : this takes place in 
all the winged insects. They frequently 
change their skin in the progress of their 
growth. A very great number of insects 
are furnished with jaws placed transversely. 
The wings, with which a very great num- 
ber of insects are furnished, distinguish 
tuem from all other animals which are not 
tarnished with a spine composed of verte- 
INS 
bra?. Insects are generally oviparous; scor- 
pions and aphides, during the summer 
months, are viviparous. Insects have no 
nostrils, are destitute of voice : they are 
not furnished with a distinct heart, com- 
posed of ventricle and auricle. Incubation 
is not necessary for hatching their eggs. 
Insects, like all other organized bodies, 
which form the animal and vegetable king- 
doms, are composed of fluids and solids. In 
the four superior classes of animals, viz. 
quadrupeds, birds, reptiles, and fishes, the 
bones form the most solid part, and occupy 
the interior part both of the trunk and 
limbs ; they are surrounded with muscles, 
ligaments, cellular membrane, and skin. 
The matter is reversed in the class of in- 
sects; the exterior part is most solid, serv- 
ing at the same time both for skin and 
bones ; it encloses the muscles and internal 
organs, gives firmness to the whole body, 
and, by means of its articulations, the limbs, 
and different parts of the body, perform 
their various motions. In many insects, 
such as the crab, lobster, &c., the external 
covering is very hard, and destitute of or- 
ganization ; it is composed of a calcareous 
earth, mixed with a small quantity of gela- 
tine, formed by an exudation from the sur- 
face of the body. As its great hardness 
would check the growth of the animal, na- 
ture has provided a remedy ; all of these 
crustaceous insects cast their shell annually. 
See Crusts. The skin of most of the other 
insects is softer and organized, being form- 
ed of a number of thin membranes, adhering 
closely to one another, and putting on the 
appearance of horn. It owes its greater 
softness to a larger proportion of gelatine. 
The muscles of insects consist of fibres form- 
ed of fasciculi ; there are commonly but 
two muscles to produce motion in any of 
their limbs, the one an extensor, the other 
a flexor. These muscles are commonly at- 
tached to a tendon, composed of a horny 
substance, connected to the part which 
they are destined to put in motion. In 
most insects, the brain is situated a little 
above the oesophagus; it divides into two 
large branches, which surround the oesopha- 
gus, and unite again under it, from which 
junction a whitish nervous cord proceeds, 
corresponding to the spinal marrow of the 
superior animals, which extends the whole 
length of the body, forming in its course 
twelve or thirteen knots or ganglions, from 
each of which small nerves proceed to dif- 
ferent parts of the body. Whether insects 
be endowed with any senses different from 
