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The non-persistence of bacterio-toxins in the soil
Published online by Cambridge University Press: 27 March 2009
Extract
The experimental results submitted in the preceding pages may be summarised as follows:
Seven English soils have been examined in order to ascertain the validity of Greig Smith’s claim that partial sterilisation effects may be due to the destruction of bacterio-toxins in the soil. The results obtained with six of these soils show that:
1. The untreated extracts of these soils varied largely in their suitability for the growth of the test organism (B. prodigiosus). In some instances vigorous growth occurred; in others the numbers of introduced organisms fell to a minimum.
2. Treatment of the extracts by heat (which was supposed to result in the destruction of “toxins”) invariably led to still further bacterial decreases.
3. Extracts of soils treated with antiseptics (which are not supposed to destroy “toxins”) were on the whole more favourable for growth than those of untreated soils. Such extracts were found to have appreciably more organic nitrogen compounds than extracts of untreated soils.
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- Copyright © Cambridge University Press 1918
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