640 NON-PATHOGENIC BACILLI. 



room temperature more rapidly at 35 C. Upon gelatin plates colonies are 

 formed resembling those of the well-known Bacillus pyocyanus, but lique- 

 faction is more rapid. In gelatin stick cultures funnel-shaped liquefaction 

 occurs at the upper part of the line of puncture by the third day, and pro- 

 gresses more rapidly than is the case with Bacillus pyocyanus under the 

 same circumstances ; on the fifth day a bluish-green color is developed ; by 

 the twelfth day liquefaction has obliterated the entire line of growth and 

 extends to the margins of the tube; the liquefied gelatin for a depth of 

 about one centimetre has a dark emerald-green color, and a film consisting 

 of bacilli is seen upon the surface. Upon the surface of agar a flat, green- 

 ish-white, dry layer is formed along the line of inoculation, and the agar 

 around, at the end of a week, acquires a bluish-green color. Upon potato, 

 at the end of three days, an abundant dry layer of a fawn-brown color has 

 developed ; this is surrounded by a pale-green coloration of the potato, and 

 at points where the surface is fissured an intense dark-green color is de- 

 veloped; the growth on potato has a more or less wrinkled appearance; 

 when one of the fawn-colored colonies is touched with the platinum needle 

 the point touched, at the end of two to five minutes, acquires an intense 

 dark leaf-green color, which reaches its maximum intensity in about ten 

 minutes, and has faded out again at the end of half an hour. Ernst con- 

 siders this " chameleon phenomenon" the most characteristic distinction 

 between the bacillus under consideration, and Bacillus pyocyanus. In milk 

 a green color is developed at the surface, the casein is precipitated and sub- 

 sequently peptonized. 



287. BACILLUS MYCOIDES ROSEUS (S(^holl). 



Found in the soil. 



Morphology . Resembles the anthrax bacillus. 



Biological Characters. An aerobic, liquefying, chromogenic bacillus. 

 Produces a red pigment when cultivated in the absence of light. Spore 

 formation not reported. Grows rapidly at the room temperature. Upon 

 gelatin plates forms colonies of interlaced filaments which cause liquefaction 

 of the surrounding gelatin. In gelatin stick cultures liquefaction rapidly 

 occurs; a red layer is formed upon the surface, and a sediment of the same 

 color is seen at the bottom of the liquefied medium, but the gelatin itself is 

 not colored. Upon the surface of agar, in the dark, a pink layer is de- 

 veloped, while in the light it is white. 



288. BACILLUS ROSACEUM METALLOIDES (Dowdeswell). 



Morphology. Bacilli from 0.6 to 0.8 n broad and about twice as long. 



Biological Characters. An aerobic, liquefying, motile (usually not mo- 

 tile), chromogenic bacillus. Forms a magenta-red pigment which has a 

 metallic lustre. Spore formation not observed. Grows best at 15 C. ; no 

 development at 35 C C. ; is destroyed in five minutes by a temperature of 55 

 C. Upon gelatin plates, at 15 C , superficial colonies are developed, which 

 in the course of a few days are elevated, colorless discs about two milli- 

 metres in diameter ; under a low power the centre appears dark, the mar- 

 gin transparent and granular; later the colony acquires a red color and 

 liquefaction of the surrounding gelatin occurs. In gelatin stick cultures a 

 red layer is developed upon the surface, and later a broad funnel of lique- 

 fied gelatin is slowly developed. Upon the surface of agar a pale-red 

 layer is formed. Upon potato, at 15 C., a thick layer quickly covers the 

 entire surface ; this has a beautiful red color, especially near the margins. 



289. BACILLUS viscosus (Frankland). 



Resembles very closely, and is perhaps identical with, Bacillus fluores- 

 cens liquefaciens. 



