Griffith’s experiment

Griffith’s experiment

• Rough strain of Streptococcus was injected into the mouse. The mouse lived.
• Smooth strain of Streptococcus was injected into the mouse. The mouse died.
• When heat-killed smooth strain of Streptococcus was injected into the mouse, the mouse lived.
• In the last set of experiments, rough strain and heat-killed smooth strain were injected into the mouse. The mouse died.

This proved that there was some substance present in heat-killed S strain that was converting or transforming the rough strain into virulent strain, leading to the death of the mouse. This transforming substance was later found to be DNA.