PSEUDOMONAS &RUGINOSA 385 



a yellowish pigment, soluable in alcohol and water, known 

 as "fluorescin." 



Cultivate the organism in one or another of the synthe- 

 sized media Frankel's modification of Uschinsky's medium, 

 for instance : 



Water distilled 1000 c.c. 



Asparagin 4 grams 



Ammonium lactate 6 grams 



Hydrogen Sod. phosphate (Na4H Po 2 ) . . . 2 grams 



Sodium chloride 5 grams 



Does it produce any color? Is chloroform extract of such 

 cultures colored? How do you explain the result? 



Obtain from the water or the soil an organism that in 

 several particulars suggests B. pyocyaneus, namely, bac- 

 illus fluorescens liquefaciens. Repeat the foregoing cul- 

 tivations and tests. In what way do the results differ from 

 those obtained with B. pyoscyaneus? 



Make two bouillon cultures of bacillus fluorescens lique- 

 faciens. Place one in the incubator and keep the other at 

 room-temperature. How do they differ at end of forty-eight 

 hours? 



Its growth in gelatin-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 ulti- 

 mately becomes fluid, the green color is confined to the 

 superficial layers in contact with the air. The form taken 

 by the liquefying portion of the gelatin in the earliest stages 

 of development is somewhat that of an irregular slender 

 funnel. (See Fig. 70.) 



On gelatin plates the colonies develop_rapidly; they 

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