Frederick Griffith Discovers Bacterial Transformation

Creative Commons Avery, O. T. et al. Studies on the chemical nature of the substance inducing transformation of pneumococcal types. Journal of Experimental Medicine. 79, 137157 (1944). Figure 1: R variant phenotypes. In this figure the colonies of R variant on the left are grown on agar in the absence of the transforming substance (x 3.5) and on the right are colonies after induction of the transforming substance.