M [Cro i irg \\ i-Ms of M \ri.i: S \i' 569 



Microscopically; edge thin, undulate, finely granular (motile or 

 ganism) ; grumose inwards center. Deep colonies yellov* brown 

 and grumose or coarsely granular. Later, macroscopically, the 

 colonies were undulate spreading; microscopically, brown and 

 grumose, the edge ragged, consisting of chains of organisms 

 extending into the medium. Spreading colonies were numerous. 

 (See Plates XV and XVI). 



Ps. fluoresceins. — Colonies at first punctiform becoming 

 round, irregular and ameboid, characteristically surrounded by a 

 hazy, ill defined, outer zone. Spiny, filamentous processes often 

 frinsred the colonies. The internal structure was at first finely 

 granular, becoming coarsely granular to grumose at the center 

 with a finely granular outer zone. Curled, interwoven filamenl 

 were frequently seen in the interior. Medium strongly fluorescent. 



Ps. longa. — Macroscopically ; punctiform, round, becoming 

 irregular or ameboid, spreading, raised and smooth; edge at first 

 entire, later more or less undulate. Microscopically; thin and 

 finely granular, the edge entire to undulate. The internal struc- 

 ture varied from finely to coarsely granular to grumose, floco i 

 or curled. 



Ps. mesenterial. — The colonies of this strain could not be 

 distinguished from those of Ps. longa except that they were fre- 

 quently thinner and more widely spreading. 



Ps. tenuis. — Punctiform becoming round or irregular. 

 Microscopically; finely to coarsely granular with edge entire to 

 broken and irregular, brownish and usually surrounded by a 

 thin transparent granular zone. 



Ps. putrida. — Punctiform to round and irregular, edge entire 

 to broken. Colonies raised, convex, smooth to slightly con 

 voluted. Microscopically; thin, finely granular to grumose, and 

 showing concentric zones with radiate to irregular surface mark- 

 ings; the edge often becoming slightly undulate. 



Strain CXII. — Colonies were round to ameboid and fre- 

 quently thin and spreading. Surface smooth, sometimes concen 

 trically ringed; usually raised, frequently becoming effuse to 



