pneumococcus colony morphology, R form

The same agar plate with colonies of Streptococcus pneumoniae in different lighting.
Left: colonies surrounded by a wide zone of alpha-hemolysis.
Right: autolysed colonies with depressed centers and undulated margins typical of R-phase colonies of pneumococci.

Cultivated on Columbia sheep blood agar aerobically, 5% carbon dioxide, 48 hours.