PYOGENIC COCCI 167 



the name staphylo, which means grape. They never form 

 chains. Spores have not been found, though the cocci are 

 very resistant (Fig. 78). 



Properties. Immotile; liquefying gelatin. Giving rise to 

 an orange-yellow pigment in the various cultures. 



Growth. It grows moderately fast at ordinary tempera- 

 ture, and can live without air, a facultative aerobin and an- 

 aerobin. 



Colonies on Gelatin. On second day small dots on the sur- 

 face, containing in their center an orange-yellow spot. The 



Fig. 78. Staphylococcus pyogenes albus (Jakob). 



gelatin all around the colony is liquefied; the size is never 

 much greater than that attained the second day. 



Colonies on A gar. The pigment remains for a long time. 



Stab-culture. At first, gray growth along the track, which, 

 after three days, has settled at the bottom of the tube in a 

 yellow, granular mass, the gelatin being all liquid (Fig. 79). 



Stroke-culture on A gar. The pigment diffused over the sur- 

 face where the growth is in moist masses. 



Potato. A thin white layer which gradually becomes yel- 

 low and gives out a doughy smell. 



