Historical theories of DNA replication
Partly due to the Meselson-Stahl experiment in 1958, semi-conservative replication is now considered to be the best description of DNA replication.
At the time, there were two alternative models of DNA replication:
Under conservative replication, the original DNA is conserved (left intact) and the daughter strand is an entirely new copy of the parent DNA.
Under dispersive replication, double-stranded sections of parent DNA are divided among the daughter molecules.