BACILLm PYOCYANEUS. 



305 



which the green coloration of the medium is especially 

 marked, add about 2 c.c. of chloroform. Shake gently, and 

 note that the chloroform extracts a blue coloring-matter 

 from the culture, leaving the latter more or less yellow. 



Its growth on gelatin in stab-cultures is accompanied 

 by liquefaction and the diffusion of a bright-green color 

 throughout the surrounding unliquefied medium. As 

 liquefaction continues, and the whole of the gelatin 

 ultimately becomes fluid, the green color is confined 



Fig. 59. 



Fig. 60. 



Colony of 5. pyoeyaneus after twenty-four hours 

 on gelatin at 20°-22° C. 



Fig. 61. 



Stab-culture of 6. 

 pyoeyaneus In gel- 

 atin after twenty- 

 eight hours at 22°C. 



1, ' ! 

 1 , 



Colony of b. pyoeyaneus after forty-two hours on 

 gelatin at 20°-22° C. 



to the superficial layers in contact with the air. The 

 form taken by the liquefying portion of the gelatin in 



20 



