EVOLUTION OF BOTULISM. I. BIOLOGICAL SIGNIFICANCE OF PATHOGENICITY,

The appearance in certain saprophytes of lethal properties can become hereditarily fixed by ensuring the particular micropopulation better nutritional conditions and as a result give rise to the formation of a pathogenic species. The occurrence of this character might have enabled the ancestors of Cl. botulinum to separate from the mass of other saprophytes and to provide unusual possibilities for circulating as well as a comparatively isolated sphere of existence. The decomposing carcass of an animal becomes a medium for multiplication and toxin formation and a source for the further spread of the microbe. A necessary condition for the hereditary fixation and further perfection of the given adaptive character in a profitable direction for the microbe is the possibility of such a mechanism of transmission recurring, the possibility of achieving the regular transmission of the pathogenic factor to a healthy organism, and the use by the microbe for this purpose of certain regular contacts between the animal and the environment. It is believed that the toxigenicity of Cl. botulinum gave rise to a specialized mechanism of transmission which, in turn, was a factor in the further evolution toward the natural selection of forms possessing more pathogenic properties and different methods of adaptation suitable to the new way of life. Author