The micro-organisms of fermentation practically considered / by Alfred Jörgensen.

  • Jörgensen, Alfred, 1848-1925.
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: The micro-organisms of fermentation practically considered / by Alfred Jörgensen. Source: Wellcome Collection.

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    we lind, undev the liead of “ Contributions ä la connaissance des organisines qui peuveiit se trouver dans la biere et le moüt de biöre, et y vivre,” the first of a series of remarkable papers by Dr. Emil Chr. Hansen. These investigations may justly be said to have inaugurated a new era in the study of the Saccharomyces and their allied organisms. Admirably prepared and disciplined for such studies, Hansen brought to bear upon them the trained mind and eye of the cryptogamic botanist, and soon struck out new and original lines of research which have led to results of the highest scientific and practical value. One great practical outcome of Hansen’s investigations has beeil to establish, contrary to the opinion of most observers before him, that the micro-organisms which exert a prejudicial effect upon our brewing processes are by no means confined to the dass of the Schizoinycetes, but that several species and varieties of the Saccliaromycetes are capable, under certain conditions, of exerting a very uufavourable influence, especially those so-called “ wild ” forms whose natural habitat is the surface of ripe fruits and grain, and which are found abundantly in the air at certain periods of the year. He has moreover shown that the supposed morpho- logical differences which have been relied upon to establish the various species and varieties of the Saccharomyces, are in the highest degree illusory and untrustworthy; in fact, that species, having very different physiological functions, may assume forms which it is impossible to distinguish by a mere microscopical examination. The methods of analysis employed by Hansen for the detection of the “ wild ” species in a yeast which, under the microscope, apparently consists of but one form, are fully described in Jörgensen’s work, and they merit our dosest attention. It is, however, in the perfection of the methods of pure yeast culture that Hansen has perhaps made- his greatest and most enduring mark upon the brewing industry. The present work contains an admirable account of these beautiful processes, by the aid of which it is now possible to cultivate, for manufacturing processes, a stock of yeast whose unmixed nature is ensured by the fact that it