Genetic Material: DNA or Proteins?

In the 1940s, a majority of scientists were under the belief that protiens were the macromolecule of genetic material but this theory was in need of scientific support.  Griffith performed an experiment proving the transformability of bacterial genetic material.  His methods were key in determining which macromolecule made genetic material.  First, he started with the controls of his experiment. A lethal S stain of bateria and injected it into mice which died and a nonlethal R strain was injected into a mice which lived.  He then went on the heat kill the lethal S strain and inject it into a mouse which lived.  Then, he took the heat killed S strain and mixed it with a nonlethal R strain and injected it into a mouse.  The mouse died.  Finally, he isolated the mixed bacteria from the deceased mouse and injected it into another mouse and that mouse died as well.  From these results, the transormability of genetic materialm was proved.  These methods were the base of Avery, McCarthy, and McLeod's experiment to determine which macromolecule of the bacterial was transformed. They used fractional analysis to isolate RNA, DNA, protiens, lipids and carbohydrates in the heat killed S strain and mixed those with the non-lethal R strain.  Whichever macromolecule killed the mouse was the macromolecule of genetic material.  DNA was the only macromolecule to result in the death of the mouse.  Other studies were performed in the next years to confirm this finding.