Abstract
Cells of Salmonella typhi murium transduced by phage P 22 are mostly lysogenic. If the cells are infected at a low multiplicity and superinfection is excluded by antiserum, the transduced cells are not immune and no free phage is found in a culture of these cells. It is concluded that the transducing particle is a defective phage and not able to establish lysogeny in the cell. The differences between specialized transduction with phage and the transduction with phage P 22 are discussed.