Harshey and Chase in their experiments labelled DNA with

Hershey and Chase in their experiments labeled DNA with ³²P.
The lack of ³²P-labeled DNA remaining in the solution after the bacteriophages had been allowed to adsorb to the bacteria showed that the phage DNA was transferred into the bacterial cell.
Hershey and Chase were also able to prove that the DNA from the phage is inserted into the bacteria shortly after the virus attaches to its host.