As early as 1846 a bold attempt had been made by Lüdersdorff [1846] to ascertain whether fermentation was or was not bound up with the life of the yeast by grinding yeast and examining the ground mass. A single gram of yeast was thoroughly ground, the process lasting for an hour, and the product was tested with sugar solution. Not a single bubble of gas was evolved. A similar result was obtained in a repetition of the experiment by Schmidt in Liebig's laboratory [1847], the grinding being continued in this case for six hours, but the natural conclusion that living yeast was essential for fermentation was not accepted, on the ground that during the lengthy process of trituration in contact with air the yeast had become altered and now no longer possessed the power of producing alcoholic fermentation, but instead had acquired that of changing sugar into lactic acid [see Gerhardt, 1856, p. 545]. Similar experiments made in 1871 by Marie von Manasseïn [1872, 1897], in which yeast was ground for six to fifteen hours with powdered rock crystal, yielded products which fermented sugar, but they contained unbroken yeast cells, so that the results obtained could not be considered decisive [Buchner and Rapp, 1898, 1], although Frau von Manasseïn herself drew from them and from others in which sugar solution was treated with heated yeast, but not under aseptic conditions, the conclusion that living yeast cells were not necessary for fermentation. Quite unsuccessful were also the attempts made to accomplish the separation of fermentation from the living cell by Adolf Mayer [1879, p. 66], and, as we learn from Roux, by Pasteur himself, grinding, freezing, and plasmolysing the cells, having in his hands proved alike in vain. Extraction by glycerol or water, a method by which many enzymes can be obtained in solution, gave no better results [Nägeli and Loew, 1878], and the enzyme theory of alcoholic fermentation appeared quite unjustified by experiment. Having convinced himself of this, Nägeli [1879] suggested a new explanation of the facts based on molecular-physical grounds. According to this view, which unites in itself some of the conceptions of Liebig, Pasteur, and Traube, fermentation is the transference of a state of motion from the molecules, atomic groups, and atoms of the compounds constituting the living plasma of the cell to the fermentable material, whereby the equilibrium existing in the molecules of the latter is disturbed and decomposition ensues [1879, p. 29]. [p016]