A few years ago M. Pouchet announced that he had repeated. Sehulze's experiment with every precaution, but that animalcules and plants were invariably developed in the infusion on which lie operated. To • prove that the atmospheric air contained no germs, he substituted artificial air—that is to say, a mixture of 21 parts of oxygen gas with 79 of nitrogen. The air was introduced into a flask containing an infusion of bay, prepared with distilled water and hay that had been exposed for twenty minutes to a temperature of 212°. He thus apparently guarded against the presence of germs or animalcules in the infusion or in the air. The whole was then hermetically sealed, so that no other air could gain access; yet after all these .,precautions, minute animal and vegetable Organisnas appeared in the infusion, He'repeated the experiment with pure oxygen gas instead of air, and obtained similar results. These experiments are described by Pouchet in the Annales des Sciences Naturelles (1858, 4th series, vol. ix. p. 372), and the same volume contains important articles by Milne Edwards, and by De Quatrefages, in opposition to Pouchet's views.
A. very large majority of our physiologists of the present day reject the doctrine; most of the apparently exceptional cases, as, for example, the mysterious presence of the entozoa, have been found to admit of ready explanation; and if we do not deny the possibility that animalcules may be generated spontaneously, we may at all events assert that such a mode of generation is not probable, and has certainly not been proved to exist. Those who wish to know more fully the arguments that may be adduced in favor of, and• in opposition to, the doctrine, are referred, on the one hand, to Pouchet's Heterogenie, ou Traite de la Generation Spontanee, base sur de Nouvelles Experiences (1859); and, on the other, to Pasteur's Mentoire sur les Corpuscles Organ ises qui 6ristent dana l' Atmosphere,. Examen de in Doctrine des Generations Spontanees, in the Annales de Chimie et de Physique (8d ser. 1862, vol. lxiv. pp. 1-110). The subject was discussed by prof. Huxley in his address to the British association in 1870.