PUTREFACTIVE ORGANISMS 109 



included in the genus Pseudomonas. B . fluorescens is markedly 

 aerobic, stains very slightly or not at all by Gram's method, and 

 is somewhat difficult to stain with any dye except hot carbol- 

 fuchsin. It grows rapidly at 20 C., and does not form spores. 



Gelatine. On gelatine the surface colonies are round at first, 

 later somewhat irregular in outline, and producing rapid lique- 

 faction ; the deep colonies are pale yellow or greenish yellow. 

 The liquefied material exhibits a characteristic yellowish or 

 bluish-green fluorescence ; in it the bacterial colonies are found 

 as flocculi or crumbly masses, which settle to the bottom of the 

 liquid. The gelatine stab liquefies in the form of a cylinder, 

 with funnel-shaped depression at the surface. 



Agar. Colonies moist, rounded, yellowish or greenish, with 

 fluorescent border. 



Potato. Growth moist, slightly raised, yellowish at first, later 

 pale sepia brown. 



Bouillon. Becomes very turbid, with a pellicle on the surface, 

 and shows a striking yellowish green fluorescence ; usually only 

 traces of indole are found. 



Milk is gradually changed to a yellowish-green alkaline liquid, 

 generally without previous coagulation ; any curd which is pre- 

 cipitated soon dissolves. 



Sugar. Glucose bouillon is rendered acid without develop- 

 ment of gas. 



A number of allied forms are known, which are possibly 

 varieties of one species. The " green " and " blue " pus organ- 

 ism, Bact. pyocyaneum, Fliigge, a pathogenic species or form 

 commonly associated with pus of wounds which heal unsatisfac- 

 torily, is very nearly related, or merely a modification of Bact. 

 fluorescens liquejaciens. The two organisms are morphologically 

 alike, and in many physiological characters very closely resemble 

 each other also. 



Another organism, Bact. fluorescens non-liquefaciens, Eisenberg 

 (Bact. immobile, Kruse), resembles the type, but liquefies gelatine 

 very slightly. It is nearly related, if not identical, with Bact. 



