

20 THE INSECT WORLD. 
described by anatomists under the name of brain. “ This ex- 
pression,” says M. Lacordaire, “ would be apt to mislead the 
reader, as it would induce him to suppose the existence of a concen- 
tration of faculties to assemble the feelings and excite the move- 
ments, which is not the case. The same naturalist observes, 
‘All the ganglions of the ventral chain are endowed with nearly 
the same properties, and represent each other uniformly.” 
The ganglion situated above the csophagus gives rise to 
the optic nerves, which are the most considerable of all those of 
the body, and to the nerves of the antenne. The ganglion 
beneath the csophagus provides the nerves of the mandibles, of 
the jaws, and of the lower lip. The three pairs of ganglions 
which follow those placed immediately below the cesophagus, 
belong to the three segments of the thorax, and give rise to 
the nerves of the feet and wings. They are in general more 
voluminous than the following pairs, which occupy the abdomen. 
Fig. 15 represents the nervous system of the Carabus auratus ; 
Ais the cephalic ganglion; B, the sub-cesophagian ganglion; c, 
the prothoracic ganglion; p and E are the ganglions of the meso- 
thorax and metathorax. The remainder, F F, are the abdominal 
ganglions. 
99 & 
Before finishing these preliminary observations, it 18 necessary 
to say that the preceding remarks only apply absolutely to 
insects arrived at the perfect state. It is important to make 
this remark, as insects, before arriving at that state, pass through 
various other stages. These stages are often so different from 
each other, that it would be difficult to imagine that they are 
only modifications of the same animal; one would suppose that 
they were as many different kinds of animals, if there was not 
abundant proof of the contrary. 
The successive stages through which an insect passes are four 
in number: the egg ; the larva; the pupa, nymph or chrysalis ; and 
the perfect insect or imago. 
The egg state, which is common to them, as to all other articu- 
late animals, it is unnecessary to explain. Nearly all insects lay 
eggs, though some few are viviparous. ‘There often exists in the 
extremity of the abdomen of the female a peculiar organ, called 
* Introduction 4 l’Entomologie, tome ii. p. 192. In 8vo. Paris. 1838. 
