Various conjectures have, at different periods, and by eminent philosophers, been held respecting the nature and origin of this important principle, but it still remains involved in obscurity. In a late Dissertation, addressed to the President and Fellows of the College of Physicians, Dr. Beattie resolves it into that inherent tendency to approximation and cohesion, in some parts of matter, and that resilition and elasticity in others, the source of which is yet undiscovered, and which is not deducible from any material, secondary cause. As it was found that no animal could exist when suddenly deprived of large quantities of blood, it was inferred that this fluid was the vital principle; an opinion, indeed, which was much strengthened by the injunction of the Mosaic Law, not to eat meat in which there was blood, "that being the life." A late celebrated anatomist adopted this opinion, and boldly declared that the blood was alive. By some physiologists it has been conjectured, that the electric fluid is the source and principle of animal life: on the contrary, modern chemists maintain that it is conveyed by that elastic elementary gas, termed oxygen, or vital air, which, according to their notions, is the true principle of vitality.
Without entering into a minute investigation of these theories, it will be sufficient to state a few of the leading circumstances which accompany the progress towards animation.
Heat is a material agent in the production and continuation of life, as is beautifully illustrated in the incubation, or hatching of an egg; the progress of which towards maturity, is nearly as follows:—On the first day, no perceptible alteration takes place; on the second, the treadle changes to a pale yellow colour; and every following day it becomes yellower, till at length it grows red, and afterwards of a deep blood-colour, which soon thickens to a firmer substance; this speedily assumes a form, which, when it thickens into life, is nourished by the yolk, and laid in the white as in a bed provided for its accommodation; thus it continues increasing, till it grows too large for its narrow bounds, when it bursts tire walls of its prison, and comes forth a perfect animal.
ANIMAL MAGNETISM, or the art of curing diseases by the magnet, was invented by a German philosopher, named Father Hehl, of Vienna, who first applied it to medicine: but the noted Mesmer, a physician of the same city, by adopting his principles, and afterwards carrying them to a greater extent, has been generally considered the author of this splendid, but fanciful system. The principles of that delusive art, are described by him in the following manner:—Animal magnetism is an universal fluid, constituting an absolute plenum in nature, and the medium of all mutual influence, between terrestrial, animal, and celestial bodies. It is a most subtle fluid, capable of flux and re-flux, and of receiving, propagating, and continuing all kinds of motion. The human body has poles, and other properties, analogous to the magnet, and is subjected to its influence, by means of the nerves. The action and virtue of animal magnetism may be transferred from one body to another, whether animate or inanimate. It
