PYOGENIC COCCI 1 69 



derived from the person affected, although stock vaccines 

 have been used with some success. 



The Opsonic Index. It was proposed by Wright that the 

 opsonic index should be obtained before treatment with vac- 

 cines, although most of the treatment is now given without 

 such control. 



Micrococcus Pyogenes Citreus (Passet). This lique- 

 fies gelatin less rapidly than the pyogenes aureus, and forms 

 a citron-yellow pigment instead of the orange-yellow of the 

 aureus. 



Micrococcus Cereus Albus (Passet). Differs from the 



Fig. 80. Micrococcus tetragenus in sputum (tubercle bacillus also). 



pyogenes albus in the form of colony. A white, shiny growth, 

 like drops of wax; hence the name, cereus. 



Micrococcus Cereus Flavus (Passet) . A lemon-yellow 

 colored growth after a short time, otherwise not differing from 

 cereus albus. 



Micrococcus Pyogenes Tenuis (Rosenbach) . Origin. 

 Found in the pus of large inclosed abscesses. 



Form. Cocci, without any especial arrangement. 



Properties. Not much studied. 



Growth. Cultivated on agar, it forms clear, thin colonies; 

 along the needle-track an opaque streak, looking as if var- 

 nished over. 



