Injecting mice with live R strain mixed with heat-killed S strain resulted in:

1. Live R alone was harmless and heat-killed S alone was harmless. 2. In a third set of experiments, a mixture of live R strain and heat-killed S strain were injected into mice. 3. To Griffith's surprise, the mice died. 4. Something from the dead S cells had converted the live R cells into a pathogenic form. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 14 'DNA Structure and Function', sections 14.1-14.6_