Final answer:
In Griffith's transformation experiments, the heat-killed S strain and live R strain were injected into a mouse. The mouse died and the S strain was recovered. This indicated that something from the heat-killed S strain transformed the R strain into the S strain.
Step-by-step explanation:
In Griffith's transformation experiments, he used two strains of S. pneumoniae. The R strain is non-pathogenic, while the S strain is pathogenic and causes death. When Griffith injected a mouse with the heat-killed S strain and a live R strain, the mouse died. The S strain was then recovered from the dead mouse. This led Griffith to conclude that something had passed from the heat-killed S strain to the R strain, transforming the R strain into the S strain.