 Embracing this chemical perspective, several chemists sought to identify the chemical catalysts needed for the reactions to occur. Fermentation was a common focus and Kühne (1877) coined the term enzyme (Greek for “in yeast”) for the putative catalyst operative in yeast. Enthusiasm for this effort was temporarily dampened by Pasteur (1860). A noted chemist, he nonetheless maintained that fermentation could only be carried out in whole living cells. This reflects a conception of the cell as an explanatorily irreducible unit of life—a conception associated with vitalism (discussed in more detail below). Enthusiasm for the factory conception, though, was rekindled by Buchner (1897). Guided by Pasteur’s contention that fermentation could not occur in the absence of cells, he added sugar to an extract he prepared by destroying all whole cells, thinking it would serve as a preservative. When he observed the emission of bubbles, indicating fermentation in the absence of living cells, he changed course and galvanized the pursuit of chemical investigations of metabolism that resulted in the establishment of modern biochemistry in the first decades of the twentieth century (Kohler 1971; Cornish-Bowden 1997). One of its early successes was the characterization in the 1930s of a pathway of enzyme catalyzed reactions responsible for fermentation (Bechtel 1986).