Magnified 100x, this 1977 photograph depicted a Petri dish filled with trypticase soy agar medium containing 5% defibrinated sheep's blood, i.e., blood agar plate (BAP). After having been inoculated, using a stab technique, with alpha-hemolytic Streptococcus anginosus
bacteria, i.e., a member of the Gram-positive viridans group of streptococci (VGS), the BAP was incubated in a carbon dioxide enriched atmosphere at 35o
C for 24 hours. The culture grew bacterial colonies. In this view, one can see numbers of colonies that were growing at the edge of the stab, surrounded by the characteristic color changes, i.e., a hazy, faded, and indistinct region in which some of the red blood cells (RBCs) were destroyed in the blood agar medium, or "hemolyzed", indicating that these bacteria were indeed alpha-hemolytic in nature.