XOX-PATHOGENIC BACILLI. 685 



than the central portion of the colony ; under a low power it is seen to be 

 formed of an innumerable series of skein-like bundles, arranged side by 

 side and more or less twisted, which proceed from the central mass. In 

 gelatin stick cultures, at the end of forty-eight hours, a small, flat mass is 

 developed at the point of puncture, and a scanty growth is seen along the 

 line of inoculation. On the fourth day the superficial growth covers the 

 entire surface, it is translucent by transmitted light and white by reflected 

 light; by the sixth day the gelatin is liquefied to a depth of one centimetre 

 below the superficial growth ; the liquefied gelatin remains transparent ; 

 upon the surface is seen a white, membranous layer, and at the bottom a 

 rather scanty white deposit ; liquefaction slowly extends downward, and by 

 the twelfth day has reached a level corresponding with the bottom of the 

 line of puncture. Upon the surface of agar, at the end of twenty-four hours 

 at 36 to 38 C., a dull- white layer, having a thickness of about one milli- 

 metre, is developed ; this is easily broken up with the platinum needle. In 

 neutral bouillon a slight cloudiness is quickly produced, a thin film forms 

 upon the surface, and a scanty white precipitate at the bottom of the tube. 

 Upon potato, at the end of forty-eight hours, a layer the size of a five-franc 

 piece is developed, which has a pale-pink color and a rough surface resem- 

 bling a lichen. Blood serum is liquefied rather rapidly, and acquires a 

 brownish color, while an abundant white precipitate accumulates at the 

 bottom of the tube. 



397. BACILLUS / OP VIGNAL. 



Found by Yignal in the salivary secretions of healthy persons. 



Morphology. Bacilli with slightly rounded ends, from 0.8 to 1.2 u in 

 length when cultivated upon agar, and from 1.4 to 2.4 u when cultivated in 

 neutral bouillon ; usually solitary, occasionally united in short chains. 



Biological Characters. An aerobic, liquefying bacillus. Spore forma- 

 tion not observed. Motility not mentioned. Grows rather slowly at the room 

 temperature more rapidly at 37 C. Upon gelatin plates, at the end of forty- 

 eight hours, small, projecting, opaque, white colonies are developed ; at' the 

 end of four days the colonies are seen as conical, opaque, white masses, di- 

 vided into about twenty segments by grooves which start from the summit. 

 In gelatin stick cultures a small but prominent white mass is seen at the 

 point of puncture, and a scanty line of development along the track of the 

 inoculating needle; on the fourth day the surface growth has extended 

 nearly to the walls of the tube, and just below this some fine branches are 

 given off from the line of growth ; the sixth day the entire surface is covei'ed 

 and the gelatin below is liquefied for a short distance; the eighth day the 

 liquefaction has extended downward, and the solid gelatin below has a 

 clouded appearance owing to the development of a quantity of small, white 

 colonies ; by the twelfth day the liquefied gelatin has a depth of about two 

 centimetres, a shining, white mycoderma is seen upon the surface, a white 

 deposit at the bottom, and below this numerous small colonies in the solid 

 gelatin. Upon the surface of agar very adherent, white colonies are 

 formed, which later extend to form a transparent, white membrane. In 

 neutral bouillon a slight cloudiness is produced, and a very scanty, whitish 

 deposit is seen at the bottom of the tube. Does not develop well in acid 

 bouillon. Upon blood serum a whitish layer is formed, which later becomes 

 semi-transparent and causes a slow liquefaction of the medium. Uponpo- 

 tato, at the end of forty-eight hours, a layer is developed which has a vel- 

 vety appearance in the centre, and a yellowish or brownish-white color ; 

 by the end of forty -eight hours this layer is as large as a five-franc piece. 



398. BACILLUS BUCCALIS FORTUITUS. 



Synonym. Bacillus./, Vignal. 



Found by Vignal in the salivary secretions of healthy persons. 



59 



