Micro-Organisms and Fermentation

ISBN: 9781330222492 出版年：2016 页码：331 Alfred Jorgensen Forgotten Books

Beer yeast was sown on a moist slice of bread; the culture was carefully covered with a glass shade, and all manner of precautions were Observed in order to protect the growth from external contamination. After some days a growth of mould appeared, as is always the case with moist bread; and the conclusion was therefore drawn that the beer yeast was the origin of the mould, and that, consequently, yeast and mould fungi were different phases of development of one and the same species. A number of years elapsed before what are now universally acknowledged to be the Obvious requirements of such investiga tions were put in practice, namely, that the first thing to be ascertained is the point from which to start before any con elusions can be drawn. This requirement was gradually defined with greater precision, and at last, as we shall see later, a point was reached which satisfies this demand in a higher degree than has hitherto been the case in the allied branches of science. A microscope capable of magnifying to the extent of 1000 diameters is, as a rule, necessary for the investigation Of micro organisms. F or the yeast and mould fungi the only preparation generally required consists in placing a drop of the liquid con taining the organisms on an Object-glass, and spreading it out in a thin layer by means of a cover — glass. When cultivated on solid substances, a very small portion of the growth is first mixed with a drop of water. At any rate, the preliminary examination of bacteria must always be performed in this manner.