CLASS I. INSECTA. 
537 
imperceptible without the aid of a microscope. You now view it furnished with wings capable 
of rapid and extensive flights ; of its sixteen feet, ten have disappeared, and the remaining six are 
in most respects wholly unHke those to which they have succeeded; its jaws have vanished, and 
are replaced by a curled-up proboscis, suited only for sipping liquid sweets ; the form of its head 
is entirely changed ; two long horns project from its upper surface ; and instead of twelve invis- 
ible eyes, you behold two, very large, and composed of at least seventeen thousand convex lenses, 
each supposed to be a distinct and effective eye ! 
" Were you to push your examination further, and by dissection to compare the internal con- 
formation of the caterpillar with that of the butterfly, you would witness changes even more ex- 
traordinary. In the former you would find some thousands of muscles, which in the latter are 
replaced by others of a form and structure entirely difi"erent. Nearly the whole body of the 
caterpillar is occupied by a capacious stomach. In the butterfly it has become converted into 
an almost imperceptible thread-like viscus ; and the abdomen is now filled by two large packets 
of eggs, or other organs not visible in the first state. In the former, two spirally-convoluted 
tubes were filled with a silky gum ; in the latter, both tubes and silk have almost totally van- 
ished, and changes equally great have taken place in the economy and structure of the nerves 
and other organs. 
" What a surprising transformation ! N"or was this all. The change from one form to the 
other was not direct. An intermediate state not less singular intervened. After casting its skin, 
even to its jaws, several times, and attaining its full growth, the caterpillar attached itself to a 
leaf by a silken girth ; its body greatly contracted, its skin once more spHt asunder, disclosing 
an oviform mass, without exterior mouth, eyes, or limbs, and exhibiting no other symptom of 
life than a slight motion when touched. In this state of death-like torpor, and without tasting 
food, the insect existed for several months, until at length the tomb burst, and out of a case not 
more than an inch long and a quarter of an inch in diameter, proceeded the butterfly before you, 
which covers a surface of nearly four inches square. Almost every insect which you see has un- 
dergone a transformation as singular and surprising, though varied in many of its circumstances." 
From these striking and beautiful general views, we must pass to a particular description of 
the wonderful races under consid- 
eration. Insects, in .their perfect 
state, are distinguished from the 
other articulate animals by the 
possession of six legs and two an- 
tennae, and by the division of the 
body into three distinct regions, 
the head, thorax, and abdomen, as 
exhibited in the annexed fio-ure. 
The second of these divisions 
bears the organs of motion. In- 
sects respire by trachea?, are gen- 
erally furnished with wings, and 
almost always undergo a series of 
transformations or metamorj^hoses 
before arriving at their mature 
and reproductive form. 
Their bodies are composed of 
distinct rings or segments, and 
these are generally of a horny con- 
sistency, united to each other by 
a membraneous skin which gives flexibility to the whole. In some cases, however, the skin is 
of a softer texture ; but even in these it presents sufficient firmness for the attachment of the 
muscles, and the tubes composing the Hmbs are generally of a harder consistence than the rest 
of the integument. The number of segments of which the body of an insect is normally com- 
VoL. II.— 68 
Antenna 
Eyes 
1st pair of Legs 
1st pair of Wings 
2d pair of Legs 
2d pair of Wings - 
8d pair of Legs 
— Head. 
Thorax. 
,. Abdomen. 
Tibia- 
Tarsus ■■ 
ANATOMY OF THE EXTBKNAL SKELETON OF AN INSECT. 
