Louis Pasteur : his life and labours by his son-in-law. Translated from the French by Lady Claud Hamilton, with an introd. by John Tyndall.

  • Vallery-Radot, René, 1853-1933.
Date:
1886
Catalogue details

Licence: Public Domain Mark

Credit: Louis Pasteur : his life and labours by his son-in-law. Translated from the French by Lady Claud Hamilton, with an introd. by John Tyndall. Source: Wellcome Collection.

Provider: This material has been provided by the Gerstein Science Information Centre at the University of Toronto, through the Medical Heritage Library. The original may be consulted at the Gerstein Science Information Centre, University of Toronto.

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    culties fell rapidly before him. He proved the ferment of lactic acid to be an organism of a certain kind. The ferment of butyric acid he proved to be an organism of a different kind. He was soon led to the\ fundamental conclusion that the capacity of an organ- ism to act as a ferment depended on its power to live without air. The fermentation of beer was sufficient to suggest this idea. The yeast-plant, like many others, can live either with or without free air. It flourishes best in contact with free air, for it is then spared the labour of wresting from the malt the oxygen required for its sustenance. Supplied with free air, however, it practically ceases to be a ferment; while in the brewing vat, where the work of fermentation is active, the budding torula is completely cut off by the sides of the vessel, and by a deep layer of carbonic acid gas, from all contact with air. The butyric fer- ment not only lives without air, but Pasteur showed that air is fatal to it. He finally divided microscopic organisms into two great classes, which he named respectively arables and ancerobics, the former requir- ing free oxygen to maintain life, the latter capable of living without free oxygen, but able to wrest this element from its combinations with other elements. This destruction of pre-existing compounds and forma- tion of new ones, caused by the increase and multipli- cation of the organism, constitute the process of fermentation.