This method is usually used when inoculating a BAP to observe hemolysis within the agar plate itself, thus you are doing your four quadrant streak and usually in the first quadrant you stab the agar. By stabbing the agar allows the technologist, microbiologist, scientist, etc to observe the detection of streptolysin O that is produced by Streptococcus pyogenes. This hemolysin is inactivated by O2 and is only seen subsurface (in an anaerobic environment) around the stab mark.
