NON-PATHOGENIC BACILLI. 623 



Biological Characters. An aerobic, non-liquefying, motile, chromo- 

 genic bacillus. Forms a grayish-yellow pigment. Spore formation not 

 positively determined, but unstained bodies resembling spores are seen in 

 the rods. The short bacilli only are motile, the longer filaments not. Upon 

 gelatin plates the deep colonies are small, spherical, and white with a green- 

 ish lustre; under a low power they are seen to be yellowish, sharply de- 

 fined, and the interior is marked by contorted stripes. The superficial 

 colonies are at first quite thin, nearly circular in form, and with a pearly 

 lustre ; they increase rapidly in size, and at the end of three days appear as 

 yellowish-green patches which may be as much as nine millimetres in dia- 

 meter ; the margins are very thin and appear to be permeated with yellow- 

 ish-white threads ; under a low power the superficial colonies are seen to be 

 striped by broad, convoluted bands resembling the intestine of a small ani- 

 mal. In gelatin stick cultures a very thin layer first forms, which later be- 

 comes thicker at the centre and soon reaches the walls of the test tube ; at 

 first it has a blue and later bluish-green fluorescence. Upon the surface of 

 agar a rather thin layer is developed and the agar acquires a greenish-yellow 

 color. Upon potato a thin, gray layer with a yellowish reflection and 

 moist, shining surface extends over the surface. 



246. BACILLUS FLUORESCENS TENUIS (Zimmermann). 



Found in the Chemnitz water supply. 



. Morphology. Short, thick bacilli with round ends, from 1 to 1.85 fit long 

 and about 0.8 M thick; one or both ends are somewhat pointed ; the rods 

 are associated in irregular groups, and in old cultures often in chains con- 

 taining four to six elements. 



Biological Characters. An aerobic, non-liquefying, motile, chromo- 

 genic bacillus. Forms a greenish-yellow, fluorescent pigment. Spore for- 

 mation not determined. Grows rather rapidly in the usual culture media 

 at the room temperature. Upon gelatin plates thin, shining superficial 

 colonies are developed, which are irregularly circular in outline and have a 

 radiate-cleft margin ; the gelatin acquires a green color far beyond their 

 boundary. In gelatin stick cultures a thin layer is formed upon the surface, 

 which afterwards becomes thicker, of a grayish-white color, and extends to 

 the walls of the test tube in about four days ; the gelatin acquires a beautiful 

 yellow color near the surface ; by reflected light the surface growth is at 

 first blue and later bluish-green; the line of puncture is marked by a scanty 

 development which does not become any more pronounced. Upon the sur- 

 face of agar a smooth, gray, shining, and rather scanty layer is developed; 

 the agar gradually acquires a greenish color. Upon potato a thin, grayish- 

 yellow, shining layer is developed along the impfstrich; later this acquires 

 a reddish-brown color. 



247. BACILLUS FLUORESCENS NON-LIQUEFACIENS. 



Found in water. 



Morphology. Short, slender rods with round ends. 



Biological . Characters. An aerobic, non-liquefying, non-motile, chro- 

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

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

 temperature not in the incubating oven. Upon gelatin plates forms fern- 

 shaped superficial colonies, around which the gelatin has a pearly lustre. 

 In gelatin stick cultures very scanty growth occurs along the line of punc- 

 ture ; the superficial growth has a fluorescent shimmer. Upon the surface of 

 agar a layer is formed having a greenish color. Upon potato a rapidly de- 

 veloped, diffuse, brownish layer is formed, and the surface of the potato 

 acquires a grayish-blue color. 



