. Here are data from several complementation experiments, involving rapid-lysis mutations in genes rIIA and rIIB. The strain designated L51 is known to have a mutation in rIIB. Phage Mixture Complementation L91 and L65 No L65 and L62 No L33 and L47 Yes L40 and L51 No L47 and L92 No L51 and L47 Yes L51 and L92 Yes L33 and L40 No L91 and L92 Yes L91 and L33 No List which groups of mutations are in the rIIA gene and which groups are in the rIIB gene.