The cephalic ganglions are two in number; they have been described by anatomists under the name of brain. "This expression," says M. Lacordaire, "would be apt to mislead the reader, as it would induce him to suppose the existence of a concentration of faculties to control the feelings and excite the movements, which is not the case."[4] The same naturalist observes, "All the ganglions of the ventral chain are endowed with nearly the same properties, and represent each other uniformly." [4] "Introduction à l'Entomologie," tome ii. p. 192. 8vo. Paris. 1838. The ganglion situated above the oesophagus gives rise to the optic nerves, which are the most considerable of all those of the body, and to the nerves of the antennæ. The ganglion beneath the oesophagus 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 oesophagus, 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_: A is the cephalic ganglion; B, the sub-oesophagian ganglion; C, the prothoracic ganglion; D and E are the ganglions of the mesothorax and metathorax. The remainder, F F, are the abdominal ganglions. Before finishing these preliminary observations, it is 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. [Illustration: Fig. 15.--Nervous system of Carabus auratus.] 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 articulate 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 the ovipositor, which is destined to make holes for the reception of the eggs. By a wonderful instinct the mother always lays her eggs in a place where her young, on being hatched, can find an abundance of nutritious substances. It will not be needless to observe that in most cases, these aliments are quite different to those which the mother seeks for herself.