"The present status of surgery depends, primarily, upon the efforts of chemists, especially those interested in wine and beer production, to determine why milk turns sour, grape juice becomes wine, wine vinegar, and vinegar "a foul, insipid fluid," without the addition of any chemical reagent. The difficulty in explaining this change was due to the fact that no chemical formula could be evolved which fully represented the equation. It was easy to write a formula that expressed in definite terms the change that had resulted in a given case, but it was impossible to explain what had set the process in motion. Why was it that milk would change from sweet to sour, showing that the milk sugar it contained had become lactic acid, while a solution of pure milk sugar in pure water absolutely refused to undergo the same process? It became evident that there was something else inherent to the fermenting process that set it in motion. ... The problem was gradually clearing up as far back as Von Helmont... who first showed that the gas eliminated during fermentation was different from the air and identical with that formed by the combustion of charcoal and the calcination of limestone. ... Stahl... was the first to discover that vinous fermentation and putrefaction belong to the same class of phenomena... Leuwenhoek... in 1680 found, with the imperfect microscopes in use at that time, that yeast consisted of minute globular or ovoid particles... It took until 1836 for Schwann and Caignard-Latour, acting independently of one another, to prove that Leuwenhoek's globules were membranous bags, exhibiting the characteristics of vegetable cells and increasing and multiplying rapidly in the same way when brought under proper conditions. It had already been recognized that the yeast increased in vinous fermentation, and therefore it was natural that they should conclude that yeast was a plant, and that as it grew it in some unexplained way set up the chemical change. ... Schroeder and Von Dusch (1854) published the fact that a cotton plug prevented the something in the air that set fermentation and putrefaction in motion from coming in contact with the solutions or solids that otherwise would become proper media for the setting up of the processes. In 1860, and the next few succeeding years, Pasteur settled the whole question by his masterly review of the field, and his own remarkable series of experiments. Following this came Lister's appreciation of the results of these experiments in their application to surgery..."