Strain of Effect Smooth Rough(R) Live R strain eat.killed Heat-killed S strain Live S and R strains isolated from dead mouse which have a capsule and form smooth-looking colonies. (b) Mice survived when injected with a nonpathogenic strain of R pneumococci, whls ccl e Figure 13.1 GrifTith's Transformation Experiments. (a) Mice died of pneumonia when injected with pathogenic strains of S pneumo lacks a capsule and forms rough colonies. (c) Injection with heat-killed strains of S pneumococci had no effect. (d) Injection with a live R strain and a heat-killed S strain gave the mice pneumonia, and live S strain pneumococci could be isolated from the dead mice