Abstract
In a previous report 1 it was shown that there is a marked dormancy of spores of Clostridium botulinum which have been subjected to heat in broth covered with a thin layer of oil within sealed glass tubes. It has become necessary to discontinue our observations on these tubes and the final available dormancy periods are herewith presented.
These dormancy periods cannot be assumed to be the maximum possible under the conditions of our experiments since positive tubes have continued to appear from time to time until January 1, 1928. No positive tubes were obtained on February 1, but it has not been unusual for intervals of 2 or more months to elapse between the occurrence of positive tubes. The last reading was made on February 1, which is 75 months after the first tubes of the series were heated and 67 months after the heating experiments were discontinued.
In all instances, as was stated in our previous report, 1 the contents of each positive tube were tested by subculture for the presence of living bacteria, and by guinea pig inoculation for the presence of potent toxin, before it was included in our tables.
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