Transformation, in the sense of that word as used by Fred Griffith and Oswald Avery, is one of the three cardinal mechanisms of horizontal gene transfer, the most counterintuitive phenomenon discovered by biologists in the past century. Griffith had shown that some mysterious pabulum could transform a nonvirulent type of bacteria into a virulent type. Avery’s group had shown that Griffith’s pabulum is DNA, the physical carrier of genes. And the Avery team had demonstrated that in its naked form—floating loose in the environment after having been liberated from a busted bacterial cell—DNA is
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