Yeast

(yest). The name applied to any of the various species of fungi of the genus Saccharomyces. It is best known as a ferment thriving in saccharine solutions, breaking up the sugar molecule into carbon dioxid and alcohol. In domestic economy, it is used in leavening bread, the porosity of the latter being due to the escaping carbon dioxid. It is also the e ential principle in alcoholic fermentation. In medicine, it has proved of value as an application to foul ulcers and as an internal remedy in putrid fevers. " Of great theoretical interest are some recent researches of Hensen's which open out great po ibilities in the future. In these investigations he has found that it is po ible to produce artificial varieties of yeast, the acquired properties being transmitted from one generation to another, apparently indefinitely; it is obvious that we have here the beginning, on a microscopic scale, of practices which have long been carried out on the higher plants in floriculture." (Frank land.) Y., Beer, the ferment used in brewing beer. It is a more or le pure culture of the saccharomyces cerevisivre. Y., Bottom, yeast found at the bottom of a chilled fermentation. Y. -cakes, cakes made of yeast which has been washed, dried, and pre ed. Y., German, a mixture of beer-yeast and dry starch, used for baking purposes. Y. -plant, the saccharomyces. Y. -poultice, a fermenting poultice containing yeast. Y., Top, the yeast found on the surface of fermenting liquids.