Recombination analysis of bacterial heredity.

I Five years ago, at this Svmposium. E. L. Tatum I , u , L and J. Lederberg first reported some preliminary experiments on genetic recombination in Escherichia coli K-12 (1946). This report will review subsequent developments in this research, with special emphasis on the application of recombination analysis in bacteria to problems of general genetic interest. The standard textbooks of bacteriology have emphasized simple fission to the near exclusion of other modes of bacterial reproduction. This is not surprising in view of the confusing aggregate of conflicting and unconfirmed claims of morphological observations interpreted as sexual processes (reviewed by Bisset, 1950). More authoritative claims of bacterial fusion have appeared (Braun and Elrod, 1946; Stempen and Hutchinson, 19511 but none with the essential \ concurrence of genetic investigation. On the