Structure and Evolution.- Plasmids as Organisms.- Report on a Workshop: Structure and Function.- Evolutionary Relevance of Genetic Rearrangements Involving Plasmids.- Mechanisms of Transposition in Bacteria.- Insertion of Transcriptional Elements Outside the Replication Region Can Interfere with Replication, Maintenance, and Stability of ColE1-Derived Plasmids.- Studies on the Transposition of IS1.- On the Transposition and Evolution of Tn1721 and its Relatives.- Repeated DNA Sequences Recombine 1,000 Times More Frequently in a Plasmid Than in the Chromosome of BacillusSubtilis.- Mercury Resistance Transposon Tn813 Mediates Chromosome Transfer in Rhodopseudomonas sphaeroides and Intergeneric Transfer of pBR322.- Report on a Workshop: Plasmids in Unusual Systems.- Replication, Incompatibility, and Partition.- Chairmans Introduction: Replication, Incompatibility, and Partition.- Role of the ? Initiation Protein and Direct Nucleotide Sequence Repeats in the Regulation of Plasmid R6K Replication.- Initiation of Replication of the EscherichiaColi Chromosomal Origin Reconstituted with Purified Enzymes.- Origin and Initiation Sites of ?dv DNA Replication In Vitro.- Broad Host-Range Plasmid R1162: Replication, Incompatibility, and Copy-Number Control.- Control of Plasmid Replication: Theoretical Considerations and Practical Solutions.- The Partition Functions of PI, P7, and F Miniplasmids.- Genetic Interactions of Broad Host-Range Plasmid RK2: Evidence for a Complex Replication Regulon.- Replication Determinants of the Broad Host Range Plasmid RSF1010.- Regulation of Replication and Maintenance Functions of Broad Host-Range Plasmid RK2.- Control of Chromosome Replication in Bacteria.- Stable Maintenance of Plasmid CLO DF13: Structural and Functional Relationships Between Replication, Control, Partitioning, and Incompatibility.- Replication Control for PT181, An Indirectly Regulated Plasmid.- Construction of ColE1 RNA1 Mutants and Analysis of their Function In Vivo.- Incompló%