The deciphering of the structure of DNA by James Watson and Francis Crick in 1953 suggested that each strand of the double helix would serve as a template for synthesis of a new strand. However, there was no way of knowing how the newly synthesized strands might combine with the template strands to form two double helical DNA molecules. The Meselson–Stahl experiment by American geneticists and molecular biologists Matthew Meselson and Franklin Stahl at Caltech in 1958 supported the hypothesis that DNA replication was semiconservative. In semiconservative replication, each of the two new double-stranded DNA helices consist of one strand from the original helix and one newly synthesized.
Meselson & Stahl, "The Replication of DNA in Escherichia coli," Proceedings National Academy of Sciences 44 (1958) 671-82.
J. Norman (ed) Morton's Medical Bibliography 5th ed (1991) no. 256.6.