In the lower portion of Articulated animals, such as insects, crustacea, annelids, worms, &c. &c., there is a double cord extending along the ventral side of the animal, united at equal intervals by double nerve-centres, or ganglia. These two cords diverge towards the upper end, surround the gullet, and unite again above that tube to form a distinct bilobed principal nerve-centre or brain. A third form of the nervous system is only a ring round the gullet; the points in it from whence the nerves radiate are swollen nerve-centres, or ganglia. Those on the sides and upper parts of the ring represent the brain, and supply the eyes, mouth, &c., with nerves: other centres, connected with the lower side of the ring, send nerves to the locomotive organs, viscera, and respiratory organs. In animals of a still lower grade there are single nuclei irregularly scattered, but in every case they are centres of energy from whence filaments are sent to the different parts of the creature. The last and lowest system consists of filamentous nerves, chiefly microscopic. Intelligence, or the mental principle, in animals differs in degree, though not in kind, from that in the human race. It is higher in proportion as the nervous system, especially the brain, approximates in structure to that of man; but even in many of the lower orders may be traced the dawn of that intelligence which has made man supreme on earth. Every atom in the human frame, as well as in that of other animals, undergoes a periodical change by continual waste and renovation; but the same frame remains: the abode is changed, not the inhabitant. Yet it is generally assumed that the living principle of animals is extinguished when the abode finally crumbles into dust, a tacit acknowledgment of the doctrine of materialism; for it is assuming that the high intelligence, memory, affection, fidelity, and conscience of a dog, or elephant, depend upon a combination of the atoms of matter. To suppose that the vital spark is evanescent, while there is every reason to believe that the atoms of matter are imperishable, is admitting the superiority of matter over mind: an assumption altogether at variance with the result of geological sequence; for Sir Charles Lyell observes, that ‘sensation, instinct, the intelligence of the higher mammalia bordering on reason, and lastly the improvable reason of man himself, presents us with a picture of the ever-increasing dominion of mind over matter.’