Genetic Studies of Lysogenicity in Escherichia Coli 1 Esther

R ECENT research on Escherichiu co& phages has outlined the biology of viruses that promptly lyse their bacterial hosts (DELBR~~CK 1950). In addition to the progressive parasitic relationship that these studies have analyzed, many phage-bacterium complexes persist in a more enduring symbiosis, lysogenicity. The experiments to be described in this paper were designed to probe two related questions : how is the virus of a lysogenic bacterium transmitted in vegetative and sexual reproduction? and how is a symbiotic complex established following infection by the virus, as an alternative to the parasitization and lysis of the host bacterium ? Complementary problems, especially concerning the growth and release of virus in lysogenic bacteria have received more emphasis from other workers (BERTANI 1951; LWOFF and GUTMAKN 1950; WEIGLE and DELBR~~CK 1951). ,