700 NOX-PATHOGENIC SPIRILLA. 



puncture and to a moderate extent upon the surface. In agar stick cultures 

 no growth occurs along the track of the inoculating needle ; on the surface 

 a dirty-white, pap-like layer is developed. Upon potato the growth is 

 sometimes dry, viscid, and dark-brown in color, or it may be of a mahogany- 

 brown with a moist lustre. 



425. SPIRILLUM AUREUM. 



Synonym. Vibrio aureus (Weibel). 



Found in the air and in the slimy deposit in sewers. 



Morphology. Curved rods with blunt ends, about one-half thicker than 

 the Spirillum cholerae Asiaticae, and varying greatly in length; typical 

 "commas" and S-forms are seen; also filaments of various lengths and 

 sometimes regular spiral filaments which are extremely slender ; also invo- 

 lution forms. 



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

 mogenic spirillum. Produces a golden or orange-yellow pigment. Spore 

 formation not determined. Grows rather rapidly at the room temperature 

 also in the incubating oven. Upon gelatin plates the deep colonies, at 

 the end of three days, have a diameter of 0.3 millimetre (in ten days of one 

 millimetre); under a low power they are seen to be coarsely granular, 

 spherical or whetstone-shaped, golden-yellow in the centre and later brown 

 or black, with more transparent, golden-yellow margins. The superficial 

 colonies are round, "with well-defined margins, granular, and of a pure 

 golden-yellow color; at the end of three days they have a diameter of one 

 millimetre and in ten days of three to four millimetres. In gelatin stick cul- 

 tures a tolerably abundant, finely granular growth is seen along the line of 

 puncture; upon the surface a rounded mass of a yellow-ochre color is de- 

 veloped about the point of puncture. Upon the surface of agar a dirty- 

 white layer extends over the entire surface ; later round, elevated, golden- 

 yellow islands are seen, and finally a uniform pap-like layer two millimetres 

 thick. Upon potato an abundant, thick, pap-like growth of a golden- 

 yellow or orange-yellow color. 



426. SPIRILLUM FLAVESCENS. 



Synonym. Vibrio flavescens (Weibel). 



Found in the slimy deposit of sewers. 



Morphology. The same as Spirillum aureum. 



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

 mogenic spirillum. Produces a dirty yellowish-green pigment. Grows 

 rather rapidly at the room temperature. Upon gelatin plates the colonies 

 resemble those of Spirillum aureum, except that the yellow color is developed 

 later and the shade is paler, duller, and less pure upon a transparent back- 

 ground a dirty yellowish-green. In gelatin stick cultures a finely granu- 

 lar line of growth is seen along the track of the needle, and along the mar- 

 gin of this in old cultures are coarser granular masses; upon the surface a 

 pale-yellow, flat layer with flap-like margins slowly extends from the point 

 of puncture. Upon agar a dirty-white color is developed, which gradually 

 extends to the walls of the test tube; elevated, round, yellow masses are de- 

 veloped in this, which increase in diameter, become confluent, and finally 

 form a thick and uniform pap-like layer. Upon potato an abundant dull- 

 yellow, pap-like layer. 



427. SPIRILLUM PLAVUM. 



Synonym. Vibrio flavus (Weibel). 

 Found in the slimy deposit in sewers. 

 Morphology. The same as Spirillum aureum. 



