Past experiments has paved for the way for future discoveries and progress in the scientific world. In the beginning, scientists were not sure whether or not DNA or proteins were supposed to be held accountable for the passing of heritable material. A scientist by the name of Frederick Griffith was the first to answer this question. He started of by using two strains of bacteria, the S strain and the R strain. The S strain was harmful and so every time the rats were injected, the organisms died. When the rats were injected by the R strain, the organisms lived. When the rats were injected by a dead strain of the S strain the rats lived and when the injection consisted of the R strain mixed with the dead S strain the rats died. A virus is just a protein and so whenever a protein is heated, it becomes denatured. Other s tried to prove this theory by conducting experiments on their own, people like Hershey and Chase. Hershey and Chase reinforced Griffith’s ideas of DNA being responsible for inheritable material. This is one of the many examples of how the past influences future experiments and leads the way to scientific progress.