"The pneumococcus is a Gram positive diplococcus.

Like all streptococci, it will occasionally form head-to-tail chains of organisms.

Around some organisms in this field, you may be able to discern a halo. This is indicative of capsule formation. The capsule provides a survival advantage to the pneumococcus, and is perhaps why it survives in the lung and causes lobar pneumonia following aspiration, whereas other mouth flora apparently do not."

Ó 1999- KUMC Pathology and the University of Kansas, used with permission; courtesy of Dr. James Fishback, Department of Pathology, University of Kansas Medical Center.