Final answer:
Griffith observed the death of mice injected with a mix of heat-killed virulent S strain and live nonvirulent R strain, concluding that a 'transforming principle' from the S strain converted the R strain into a virulent form.
Step-by-step explanation:
In the Griffith Transformation Study, when heat-killed S strain bacteria were mixed with live R strain bacteria and injected into mice, the unexpected result was the death of the mice. Upon further examination of the dead mice, Griffith only discovered the presence of live S strain bacteria.
This led him to the groundbreaking conclusion that a transforming principle must have been transferred from the heat-killed S strain to the live R strain, effectively transforming the R strain into a pathogenic S strain.