Vigorous growth in Slight growth in Weak growth in alkaline
alkaline nutrient alkaline nutrient nutrient fluids
fluids fluids
Active growth on potato No growth on potato On potato at 37° C. a
yellowish, becoming slight, thin gray,
darker waxy layer
On gelatine, small, On gelatine light On gelatine feeble
round brownish bluish colonies growth or none
colonies shading off
insensibly at edges