Staphylococcus Medium 110, also known as "Stone Gelatin Agar", is used for isolating and differentiating staphylococci based on mannitol fermentation, pigment formation and gelatinase activity.  Principles of the procedure: Staphylococcus Medium 110 contains peptone as a source of carbon, nitrogen, vitamins and minerals. Yeast extract supplies B-complex vitamins which stimulate bacterial growth. Sodium chloride, in high concentration, inhibits most bacteria other than staphylococci. Lactose and D-mannitol are the carbohydrates. Gelatin is included for testing liquefaction. Agar is the solidifying agent. Pathogenic staphylococci (coagulase-positive staphylococci) typically resist the high salt concentration and form colonies with a yellow-orange pigment. These organisms typically ferment mannitol and produce acid, and liquefy gelatin, producing zones of clearing around the colonies.