644 THE POPULAR SCIENCE MONTHLY. 



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 fun- 

 gus, seven proved to be intact, entirely uninvaded. Therefore, what- 

 ever 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 prepa- 

 ration 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 pre- 

 pared, 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 power- 

 less 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 



