When this organic and productive matter is found collected in a great quantity in some part of an animal, where it is obliged to remain, it forms living beings which have been ever regarded as animals; the tænia, ascarides, all the worms found in the veins, liver, in wounds, in corrupted flesh, and pus, have no other origin; the eels in paste, vinegar, and all the pretended microscopical animals are only different forms which this active matter takes of itself, according to circumstances, and which invariably tends to organization.
In all animal and vegetable substances, decomposed by infusion, this productive matter manifests itself immediately under the form of vegetation. Filaments are seen to form, which grow and extend like plants. Afterwards these extremities and knots swell and burst, to give passage to a multitude of bodies in motion, which appear to be animals; so that it seems as if all nature began by a motion of vegetation. It is seen by microscopical objects, and likewise by the expansion or unfolding of the animal embryo; for the fœtus at first has only a species of vegetable motion.
Sound food does not furnish any of these moving molecules for a considerable time. Several days infusion in water is required for fresh meat, grain, kernels, &c. before they offer to our sight any moving bodies; but the more matters are corrupted, decomposed, or exalted, the more suddenly these moving bodies manifest themselves; they are all free from other matters in seminal liquors; but a few hours infusion is required to see them in pus, spurred barley, honey, drugs, &c.
There exists therefore, an organic matter, universally diffused in all animal and vegetable substances, which alike serves for their nutrition, their growth, and their reproduction. Nutrition is performed by the intimate penetration of this matter in all parts of the animal or vegetable body. Expansion or growth is only a kind of more extended nutrition, which is made and performed as long as the parts have sufficient ductility to swell and extend; and reproduction is made by the same matter when it superabounds in the body of the animal or vegetable; each part of the body sends back, to the appropriate reservoirs, the organic particles which exceed what are sufficient for their nourishment. These particles are absolutely analogous to each part from which they are sent back, because they were destined to nourish those parts from hence, when all the particles sent back from, collect together, they must form a body similar to the first, since each particle is like that part from which it was detached; thus it is that reproduction is effected in all kinds of trees, plants, polypuses, pucerons, &c. where one individual can produce its like; and it is also the first mode which Nature uses for the reproduction of animals which have need of the communication of different sexes; for the seminal liquors of both sexes contain all the necessary molecules for reproduction; but something more is required for its effectual completion, which is the mixture of these two liquors in some places suitable to the expansion of the fœtus which must result therefrom, which place is the matrix of the female.
There are, therefore, no pre-existing germs, no germs contained one in the other, ad infinitum; but there is an organic matter perpetually active, and always ready to form, assimilate, and produce beings similar to those which receive it. Animals and vegetables, therefore, can never be extinct; so long as there subsist individuals the species will ever be new; they are the same at present as they were three thousand years ago, and will perpetually exist, by the powers they are endowed with, unless annihilated by the will of the Almighty Creator.
OF THE NATURE OF MAN.