Mixtures were centrifuged forcing the heavier bacterial cells into a pellet on the bottom of the tubes. The lighter viruses remained in the supernatant. Radioactivity in the pellet and supernatant was measured and compared. In tubes with E. coli infected with protein-labeled T2, most of the radioactivity was in the supernatant with viruses. In tubes with E. coli infected with DNA-labeled T2, most of the radioactivity was in the pellet with the bacterial cells.
Viral proteins remain outside the host cell.
Viral DNA is injected into the host cell. Injected DNA molecules cause cells to produce additional viruses with more viral DNA and proteins. These data provided evidence that nucleic acids rather than proteins are the hereditary material.