Final answer:
Griffith's transformation experiments involved injecting mice with different strains of bacteria and observing the effects. He found that a substance from dead bacteria could transform non-virulent bacteria into a deadly form. The specific identity of this substance was not determined in Griffith's experiments.
Step-by-step explanation:
Griffith's Transformation Experiments
Griffith's transformation experiments were conducted in the 1920s and involved studying two different strains of a bacterium, the S (smooth) strain and the R (rough) strain. He injected these strains into mice and observed that the S strain was virulent and killed the mice, while the R strain was non-virulent and did not harm the mice. When he injected a mixture of heat-killed S-strain bacteria and live R-strain bacteria, the mice died. This showed that some substance from the killed bacteria transformed the non-virulent strain into a virulent one.
From these experiments, Griffith concluded that there was a transforming principle transferred from the killed S-strain bacteria to the live R-strain bacteria. This principle could convert the harmless bacteria into a deadly form. However, Griffith did not determine the specific identity of this transforming principle.