Here's a breakdown of his findings:
* He used two strains of Streptococcus pneumoniae bacteria: a virulent (disease-causing) strain with a smooth capsule (S strain) and a non-virulent strain with a rough capsule (R strain).
* Injecting mice with the S strain led to their death, while injecting with the R strain was harmless.
* Heat-killed S strain bacteria, when injected, did not cause disease.
* However, when Griffith mixed heat-killed S strain with live R strain bacteria, the mice died!
* He found that the dead S strain bacteria had somehow transformed the live R strain bacteria into virulent S strain bacteria.
This experiment was groundbreaking because it showed that some factor, which we now know to be DNA, could be transferred from one bacterium to another, causing a heritable change. This was a crucial step in understanding how genetic information is passed on.