NOX-PATHOGEXIC BACILLI. 635 



drops of oil and sometimes a conglomeration of minute spherical masses. 

 Later the deep colonies are oval, dark, sharply defined, and as large as a 

 pea ; those nearer the surface are conglomerate ; those upon the surface are 

 partly homogeneous, pale-yellow, and round; some show an opaque, con- 

 glomerate mass in the centre, with a more transparent, yellowish-green 

 marginal zone ; some have a form resembling that of Saturn with its rings. 

 In gelatin stick cultures a slimy, thick, lemon-yellow layer develops upon 

 the surface ; this is gradually depressed in the middle, while the margins re- 

 main elevated and granular ; along the line of puncture small colonies are 

 developed which form a funnel above ; at the end of five to six weeks the 

 gelatin in the funnel, when shaken, appears pap-like, and the layer floats 

 upon its surface, while some greenish flocculi are seen below. Upon the 

 surface ofagar development is rapid and the entire surface is covered within 

 a few days; below, the layer consists of an abundant jelly-like growth, 

 covered with protuberances resembling drops of honey ; above, it has an 

 orange color and creamy consistence, and is covered with numerous small, 

 spherical or oval masses. Upon potato a slimy, lemon-yellow layer is 

 quickly developed and extends over the entire surface ; at the margins this 

 is more transparent and albuminous in appearance ; at the end of two weeks 

 the central portion has a greenish-yellow color, distributed like the veins of 

 a grape leaf, with smaller, pale-yellow veins. 



276. BACILLUS CCERULEUS (Smith). 



Found in water of the Schuylkill River. 



Morphology. Bacilli from 2 to 2.5 p long and 0.5 u broad, frequently as- 

 sociated in chains. 



Biological Characters. An aerobic, liquefying, chromogenic bacillus. 

 Produces a beautiful blue pigment. Spore formation not observed. Grows 

 slowly at the room temperature. Upon gelatin plates forms superficial colo- 

 nies having a blue color, around which the gelatin is liquefied. In gelatin 

 stick cultures cup-shaped liquefaction occurs at the surface and a blue color 

 is developed, while below a scanty, colorless growth occurs along the line of 

 puncture. Upon the surface ofagar a bluish layer is formed. Upon po- 

 tato at first a beautiful dark-blue layer, which later acquires an intense 

 blue-black color. 



277. BACILLUS FLUORESCENS LIQUEFACIENS. 



Found in water and in various putrefying infusions very common. 



Morphology. Short bacilli, in pairs with a constriction at the point of 

 junction. 



Biological Characters. An aerobic, liquefying, motile, chromogenic 

 bacillus. Forms a greenish-yellow, fluorescent pigment. Spore formation 

 not observed. Grows in the usual culture media at the room temperature. 

 Upon gelatin plates whitish colonies are developed upon the surface, which 

 may attain a diameter of three millimetres; a ring of liquefied gelatin forms 

 around each ; under a low power the colonies are seen to have a sharp con- 

 tour and irregularly circular outline, a dark-brown, finely granular centre 

 surrounded by a finely granular marginal zone of a yellow color, which be- 

 comes more transparent and grayish- white toward the edge; the gelatin 

 gradually acquires a greenish tint. In gelatin stick cultures a whitish 

 growth occurs along the line of puncture ; a small funnel of liquefied gelatin 

 is first seen near the surface, and this has an air bubble above; gradually the 

 liquefaction extends to the walls of the test tube and also in a downward 

 direction, forming a superficial layer of liquefied gelatin, upon the floor of 

 which a thick white deposit is formed; the gelatin below this has a green- 

 ish-yellow fluorescence and the liquefied gelatin also, although less pro- 

 nounced. Upon potato an abundant brownish layer is developed along the 

 line of inoculation. 



