NON-PATHOGENIC BACILLI. 063 



growth is seen along 1 the track of the inoculating needle, and at the surface 

 a cup-shaped depression, the size of a hempseed, which contains air; in older 

 cultures the gelatin is liquefied near the surface and a thin, dirty-yellow film 

 swims upon it. Upon the surface of agar a grayish-white layer is devel- 

 oped. Upon potato, at 15 to 20 C., a thin and broad white layer. Upon 

 blood serum a narrow, grayish-white stripe, which extends to a tolerably 

 deep channel, with irregular margins, from 0.5 to 1 centimetre wide; this is 

 lined with a slimy, grayish-white growth. Cooked fish or flesh constitutes 

 a favorable medium for the growth of this bacillus. By means of the phos- 

 phorescent light given off by cultures of this bacillus, Fischer has succeeded 

 in making photographs not only of the cultures, but of a watch dial placed 

 between two cultures an exposure of twenty-four hours' duration and a 

 very sensitive dry plate were required to accomplish this. 



344. BACILLUS PHOSPHORESCENS INDIGENUS (Fischer). 



Found in sea water from the harbor at Kiel and upon phosphorescent 

 herring. 



Morphology. Bacilli with round and slightly pointed ends; somewhat 

 shorter than Bacillus phosphorescent Indicus, but of the same thickness 

 from 1.3 to 2.1 u long and 0.4 to 0.7 /* broad; solitary or in pairs; may grow 

 out into filaments. 



Biological Characters. An aerobic, liquefying, motile bacillus. Cul- 

 tures give off a bluish- white, phosphorescent light not so intense as that 

 from Bacillus phosphorescens Indicus ; phosphorescence depends upon free 

 access of oxygen. Sea water to which a small amount of a culture is added 

 is phosphorescent in the dark Spore formation not observed. Grows at the 

 room temperature in the usual culture media more slowly than Bacillus 

 phosphorescens Indicus. Grows at 5 to 10 C., and even below; at a tem- 

 perature of 32 C. development still occurs, but the cultures do not exhibit 

 phosphorescence. Upon gelatin plates the gelatin is depressed about the 

 small spherical colonies, and at the end of a week cylindrical cavities filled 

 with air, and not more than one millimetre in diameter, are formed in the 

 gelatin ; at the bottom of these, on the surface of the plate, the colonies are 

 seen ; these are the size of a pin's head, thin, disc-formed, and dirty yellow in 

 color ; under a low power very young colonies are seen to be circular, with 

 well-defined margins, and of a pale sea-green color; here and there reddish- 

 shimmering granules are seen in the otherwise homogeneous contents ; the 

 older colonies are made up of irregular, dirty yellowish-gray masses. In 

 gelatin stick cultures, at the end of a week, a conical cavity forms near the 

 surface, which is filled with air and is lined with a thin, friable growth; at 

 the surface the mouth of the cone measures about two millimetres in diame- 

 ter; this cavity increases in dimensions without containing any liquefied 

 gelatin; in old cultures it may be three to five millimetres in diameter and 

 two to three centimetres deep, the walls being covered with a thin layer of 

 bacilli, and a mass of the same accumulating at the bottom. No growth 

 occurs upon potato or upon blood serum. 



345. BACILLUS CIRCULANS (Jordan). 



Found occasionally in. water from the Merrimac Eiver. 



Morphology. Bacilli with round ends, from 2 to 5 n long and about 1 

 H broad ; usually solitary, but sometimes in loosely connected chains of 

 three or four elements. 



Biological Characters. An aerobic and facultative anaerobic, liquefy- 

 ing, motile bacillus. Forms oval spores, which are located at the ends of 

 the rods and are of about the same diameter as these. Grows in the usual 

 culture media at the room temperature better at 37 C. Upon gelatin 

 plates, at the end of two days, round, brownish colonies become visible ; 

 under a low power the liquid contents of these colonies are seen to be in mo- 



