SPONTANEOUS GENERATION, the doctrine that living matter may originate spon taneously, that is, out of non-living matter. The sudden appearance of living things in dead bodies, as of maggots in flesh, and mold on vegetables, was formerly accounted for by re garding them as the direct products of the decay or putrefaction in which they occurred, through some unexplained process. The Italian experimenter, Spallanzani (q.v.), first indicated the probability of the source of these growths being living things or their germs pre-existing in the atmoshpere. He found that when he bound organic solutions, as beef-broth or an infusion or "tea" of hay in a vessel closed against the admission of air, no appearance of living beings, or any evidence of "generation" followed; and the same freedom continued when the air which entered vessels containing fermentable solutions was made to pass first through sulphuric acid, through redhot tubes, and through cotton-wool. That the air does actually contain large quantities of minute organic bodies was demonstrated by Tyndall in his efforts to obtain optically pure atmosphere, and this explains why preserved meats keep for any number of years if properly closed, since, after their thorough cooking, the aper tures are hermetically sealed while steam is still escaping, the entrance of atmospheric air with its contents being thus prevented. Lister's
antiseptic treatment in surgery is based on the same hypothesis.
But while spontaneous generation is unten able as an explanation of phenomena now in progress, science knows nothing of the original development of living things. Some scientists have held that life comes to the earth from other planets by light pressure moving excess ively minute forms. Others have advanced the theory that there is a life element in na ture not appreciable to man's five senses, but which under right conditions brings vegetable, animal and human life into matter. Until we know what life is no theory of spontaneous generation will maintain. Evolution is incom plete as a scheme of the universe without the hypothesis of spontaneous origin of living things from inorganic matter. Therefore, many regard life as a problem to be solved only by occult means or by the reincarnated man after the death of his physical body. This is a matter in which chemistry must be con sulted as well as biology; and the opinions of thinkers in respect to it — in general an atti tude of waiting for more light — may be found under such heads as ANIMAL; ANTISEPTIC; BAc