Page:Defensive Ferments of the Animal Organism (3rd edition).djvu/31

an accurate and possibly exhaustive study of the finer metabolic processes that go on in the cell. In these processes the so-called ferments play the most important rôle. With their aid we have succeeded in following up, outside the cell, processes which seemed to be exclusive properties of the cell. The more these experiments are extended, the more we meet with observations which show that we have been in the habit of picturing far too schematically the processes within the cell body. Thus, for instance, the simply formulated process of the fermentation of grape sugar into alcohol and carbonic acid gas—C₆H₁₂O₆ = 2C₂H₅OH + 2CO₂—has been found to be a most complicated process. A whole chain of reactions takes place, before the grape sugar is finally converted into alcohol and carbonic acid gas. There are many more intermediate stages present than were ever suspected. It will be an important duty of future research to ascertain what importance alcoholic fermentation, in all its stages, has for the yeast cell. We are indebted to recent researches, in which Knoop, Neubauer, Friedmann, Embden, Dakin, Schittenhelm, Jones and others have taken a prominent part, for a knowledge of numerous intermediate stages in the decomposition of the amino-acids, of grape sugar, of purin bases, &c. Every time we demonstrate fresh intermediate links in the decomposition of certain compounds we get a