THE HISTORY OF BACTERIOLOGY. 57 



carbonic acid gas ; that on the left was filled with concentrated sulphuric 

 acid, and the other with solution of potash. By means of the boiling heat 

 every living organism and all germs in the flask, or in the tubes, were 

 destroyed, and all access was cut off by the suphuric acid on the one side 

 and by the potash on the other. I placed this easily-moved apparatus 

 before my wmdow, where it was exposed to the action of light, and also, 

 as I performed my experiments during the summer, to that of heat. At 

 the same time I placed near it an open vessel, with the same substances 

 that had been introduced into the flask, having also subjected them to 

 the boiling temperature. In order now to renew constantly the air within 

 the flask I sucked with my mouth, several times a day, the open end of the 

 apparatus filled with a solution of potash, by which process the air entered 

 my mouth from the flask through the caustic liquid, and the atmosphere 

 entered the flask from without through the sulphuric acid. The air was of 

 course not at all altered in its composition by passing through the sulphuric 

 acid in the flask, but if sufficient time was allowed for the passage the 

 portions of living matter, or matter capable of becoming animated, were 

 taken up by the acid and destroyed. From May 28th till the beginning of 

 August I continued uninterruptedly the renewal of the air in the flask 

 without being able, without the aid of a microscope, to perceive any living 

 animal or vegetable substance, although, during the whole of the time, I 

 made my observations almost daily on the edge of the liquid, and when at 

 last I separated the different parts of the apparatus I could not find in the 

 whole liquid the slightest trace of infusoria confervse or of moulds ; but all 

 the three presented themselves in great abundance a few days after I had 

 left the flask standing open. The vessel which I placed near the apparatus 

 contained on the following day vibriones and monads, to which were soon 

 added larger polygastria, infusoria, and afterwards rotatoria." 



Schulze was thus able to prove that the sterility was not 

 dependent upon any alteration in the air within the flask, or 

 to the small quantity of air contained in it, and that it was not 

 due to any alteration brought about in the liquid by the heat- 

 ing process, as on the one hand a large quantity of air 

 was passing through the flask, whilst on the other the fluid 

 that had been boiled, but which was left exposed, rapidly 

 underwent decomposition, a decomposition that was accom- 

 panied by the development of micro-organisms in very 

 large numbers. The objection that some particles of sul- 

 phuric acid drawn in with the air might aifect the growth 

 of organisms was met by Schulze by further experiments ; 

 and Schwann, who, instead of using sulphuric acid, used 

 heat as a means of destroying any particles that might 

 be present in the air that was drawn into the flask, 

 corroborated Schulze's statements. Now came further 

 objections from the supporters of abiogenesis, who stated, 

 most definitely and categorically, that these workers were 

 not dealing with germs at all, but simply with particles of 



