INSECTS. 
deed the construction of their mouths pre- 
vents them from taking any other than fluid 
food. 
We shall now refer to the functions of in- 
sects : beginning with respiration, which is 
the act of inhaling and exhaling the air into 
and out of the lungs. Quadrupeds, birds, and 
most of the amphibia, breathe through the 
mouth and nostrils. The air, when received 
into the lungs, is mixed with the blood, and 
imparts to it something necessary, and car- 
ries off something noxious. Some authors 
have asserted, that insects have no lungs ; but 
later experiments and observations show, 
that no species wants them, or, at least, 
something similar to them ; and in many in- 
sects they are larger in proportion to their 
bodies than in other animals. In most of 
them they lie at or near to the surface of 
the body, and send out lateral pores or tra- 
cheae. 
The respiration of insects has attracted 
the attention of many naturalists, and it is 
found, that insects do not breathe through 
the mouth or nostrils ; that there are a 
number of vessels, for the reception of air, 
placed along on each side of the body, 
which are commonly called spiracula, which 
are subdivided into a number of smaller 
vessels, or bronchi*; that the vessels, or 
tracheae, which proceed from the pores on 
the sides, are not composed of a simple 
membrane, but are tubes formed of circular 
rugae ; that the spiracula are distinguish- 
able, and are covered with a small scaly 
plate, with an opening in the middle like a 
button-hole, which is furnished with mem- 
branes, or threads, to prevent the admission 
of extraneous bodies. 
Insects are the only animals without ver- 
tebrae, in which the sexes are distinguished. 
Copulation is performed in them by the in- 
troduction of the parts of generation of the 
male into those of the female. All insects 
are either male or female, except in a few 
of the genera of the order Hymenoptera, 
such as the bee, ant, &c. where individuals 
are to be found, which are neither male nor 
female; and, on that account called neu- 
ters. Among the bees, the neuters form 
the far greater part of the community, and 
perform the office of labourers. Among 
the ants, the neuters are very numerous, 
and constitute the only active members of 
the society. It has been alleged, that these 
neuters are nothing but females, whose 
parts have not been developed for want of 
proper nourishment. Olivier, however, af- 
ter strict examination, is disposed to think 
them really different, though he does -not 
adduce facts sufficient to establish his opi- 
nion. The parts which distinguish the male 
from the female, may be divided into two 
classes, viz. 1. Those which are not directly 
connected with generation. 2. Those which 
are absolutely necessary for the purposes of 
generation. The circumstances which have 
no direct communication with generation, 
which serve to point out the distinction be- 
tween the sexes, are the difference of size 
observable in the male and female ; the 
brightness of the colour in each ; the form 
and number of articulations of the anten- 
nae ; the size and form of their wings ; the 
presence or absence of a sting ; the male is 
always smaller'than the female ; the female 
ant is nearly six times larger than the male ; 
the female cochineal is from twelve to fif- 
teen times the size of the male ; the female 
termes is two hundred or three hundred 
times the size of the male ; the colours of 
the male are commonly much more brilliant 
than those of the female ; this is particularly 
the case in lepidopterous insects ; in some 
insects, the colour of the male is totally dif- 
ferent from that of the female ; the anten- 
nae of the male are commonly of a different 
form, and larger than those of the female ; 
frequently the males are furnished with 
wings, while the females have none; the 
lampyris, coccus, and blatta, and several 
moths, afford an example of this ; the fe- 
male bee is furnished with a sting, while the 
male is destitute of one ; the males of some 
insects are furnished with sharp prominent 
points, resembling horns, situated either on 
the head or breast, which are either not 
perceptible, or very faintly marked, in the 
female. The parts essential to generation 
afford the best distinguishing mark ; in most 
insects they are situated near the extremity 
of the rectum; by pressing the abdomen 
near to the anus, they may frequently be 
made to protrude ; but the parts of gene- 
ration are not always situated near the 
anus : in the spiders, they are situated in 
the feelers; in the libellula, the male organ 
is situated in the breast, while that of the 
female is placed at the anus. 
The eggs of insects are of two sorts : the 
first membranaceous, like the eggs of the 
tortoise, and the other reptiles ; the other 
covered with a shell like those of the birds ; 
their figure varies exceedingly; some are 
round, some elliptical, some lenticular, some 
cylindrical, some pyramidal, some flat, 
some square, but the round and oval are 
the most common. The eggs of insects sel- 
