Page:Popular Science Monthly Volume 10.djvu/664

644 there was no trace of any organism to be seen. In each of the other chambers one of the three tubes gave way. Each chamber contained three tubes; so that, out of nine tubes containing an infusion of fungus, seven proved to be intact, entirely uninvaded. Therefore, whatever argument or presumption was raised by the first chamber in regard to the idea that life was spontaneously generated in it, was entirely destroyed by the deportment of the other chambers. Seven out of the nine remaining intact, was sufficient to show that it was some defect in the experiment that caused the first chambers to give way so utterly. I continued the experiments, and, inasmuch as fungi disappeared on the approach of winter, other substances were chosen. I took cucumber and beet-root, having special theoretical reasons for doing so, and prepared infusions of them with the aid of my excellent assistant Mr. Cotterell. We placed these in our chambers as before, boiled them for five minutes, and abandoned them to what I supposed to be the moteless air within. Again, to my surprise, an infusion of beet-root in one chamber, and an infusion of cucumber in another, broke down. All the tubes became turbid and covered with this peculiar fatty scum. Other chambers were then tried. I had begun to suspect that we were operating in a contaminated atmosphere; that my infusions were in the midst of a pestilence which it was hardly possible to avoid. The consequence was, that I withdrew the preparation of the infusions from the laboratory down-stairs, and I went to one of the highest rooms in the Royal Institution, had the infusions prepared there, and introduced into the cases, which were afterward boiled in the laboratory below. There were a great number of these cases. The substances chosen were cucumber, beet-root, turnip, and parsnip. Great care was taken to have the infusions properly prepared, and to have them rendered as clear as possible. To give you an idea of the care taken, I may mention that the infusions of turnip and beet-root were passed through 24 layers of filtering-paper, and were thereby rendered clear; that the infusion of cucumber was passed through 120 layers of filtering-paper, and thereby rendered clear; and that the infusion of parsnip was passed through 300 layers of filtering-paper, and it was still opalescent. The suspended particles were so small that the filtering-paper had no power whatever to arrest them, and the finest microscope ever made would have proved powerless to exhibit the individual particles that produced this opalescence. Notwithstanding all this care, the chambers containing these infusions in three days became filled with bacterial life. They were turbid, covered with scum, and showed all evidences of putrefaction. This was on November 20th. On November 25th we went up-stairs and prepared another chamber, or a series of chambers. When the tubes containing the infusions were placed in the oil-bath, the liquids within the tubes opening into the case of course boiled, steam was discharged into the case, the air of the case being thereby rendered warm. It