Household bacteriology for students in domestic sciences / by Estelle D. Buchanan ... and Robert Earle Buchanan.

  • Buchanan, Estelle D. (Estelle Denis Fogel), 1876-
Date:
1913
Catalogue details

Licence: In copyright

Credit: Household bacteriology for students in domestic sciences / by Estelle D. Buchanan ... and Robert Earle Buchanan. Source: Wellcome Collection.

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    maggots would not inevitably develop in meat allowed to decay. He hit upon the simple expedient of tying a screen over the mouth of a jar to prevent the entrance of flies, and proved by his observations that maggots developed only from the eggs of the fly and could never form spontaneously. Other investigators soon showed the same facts to be true of other vermin. The theory was therefore abandoned with refer- ence to the higher animals, but not with re.spect to micro- organisms. The observation that decaying organic matter always swarmed with bacteria led to the natural assumption that they were formed dc novo as a product of the dead cells. Supposed proof of such development was furnished by boiling a decoction of some meat or vegetable, whereupon it was frequently found - that organisms developed. It was assumed that boiling was sufficient to kill all organisms, and that their development in the boiled fluid proved the contention of those who believed in spontaneous generation. We know now that some common species of bacteria may not be destroyed at this temperature, and that these conclusions were not wholly correct. Spallanzani (1777) noted that organisms usually would not develop in or- ganic materials that had been boiled for a time and hermeti- cally sealed. His results were criticized for the reason that air was e.xcluded from his flasks, and it was contended that the presence of air was essential to spontaneous generation. Schulze in 1836 passed air through sulphuric acid into flasks partially filled with boiled decoctions. He found that such air did not induce the development of the organisms. Schwann in 1837 demonstrated the same fact by passing the air through hot tubes. Even these demonstrations did not entirely disarm those who upheld the theory of spontaneous generation. They contended that air passed in this way through sulphuric acid or hot tubes was devitalized. They believed that air was an essential to spon- taneous generation through its stimulating action on the organic matter with which it came in contact; the opponents of the
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