The production of recombinants in phage crosses

The conception of a phage cross as an experiment in population genetics is now well established (Visconti and Delbrück, 1953). One thus observes the production of recombinants at a considerable remove from the hypothetical elementary acts of recombination. It might be supposed that this circumstance alone would virtually close the door to any real understanding of mechanism (Hershey and Chase, 1951). On the contrary, as the result of continuing work in this field one now knows about as much about recombination in phages as in any other material. I shall consider here an arbitrary selection of recent work, including some new experiments concerned with the effects of ultraviolet light on genetic recombination. The center of interest will be the manner of production of recombinants. Information about other important topics of phage genetics may be found in reviews by Benzer (1957), Delbrück (1958), Jacob and Wollman (1957), and Stent (1958)