634 NON-PATHOGENIC BACILLI. 



yellow colonies, around which the gelatin is liquefied in circular form. In 

 gelatin stick cultures liquefaction occurs at the surface, with formation of an 

 air bubble at the surface, a scanty, yellow deposit at the bottom of this, clear 

 liquefied gelatin below, and a yellow deposit on the concave floor of the 

 liquefied gelatin; below this, along the line of puncture, small colonies 

 are seen. The cultures give off an odor of sulphuretted hydrogen. Upon 

 the surface of agar a narrow, yellow layer forms along the impfstrich. 

 Upon potato a dry, lemon-yellow, slightly granular layer is developed. 



274. BACILLUS MEMBRANACEUS AMETHYSTINUS (Eisenberg). 



Found in a specimen of well water from Spalato. 



Morphology. Short bacilli with round ends, from 1 to 1.4 ju long and 0.5 

 to 0.8/* broad; in irregular groups; some of the rods in stained preparations 

 show end staining. 



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

 bacillus. Produces a dark-violet pigment which has a metallic lustre. 

 Spore formation not determined. Grows at the room temperature in the 

 usual culture media no development at 37. 5 C. Upon gelatin plates, at 

 the end of two to three days, colonies are developed the size of a poppy-seed, 

 which have a homogeneous, dark- violet color ; later a ring of liquefied gela- 

 tin forms around each colony, which gradually extends, and at the end of 

 one to two weeks the entire gelatin is liquefied and the colonies are seen 

 floating upon its surface, not much larger than when liquefaction com- 

 menced. When the colonies are not so closely crowded superficial colonies 

 are seen at the end of three to four days, which resemble those of the typhoid 

 bacillus ; they have a yellowish- white color and a dentate margin ; at the 

 end of ten to fourteen days the gelatin around these colonies commences to 

 soften and a dark- violet color extends from the centre to the periphery ; at 

 the end of three to four weeks the colonies are seen floating upon the surface 

 of the scarcely liquefied gelatin, as large violet layers. In gelatin stick cul- 

 tures a yellowish-white layer with dentate borders develops upon the 

 surface, which at the end of ten to fourteen days begins to acquire a violet 

 color at the centre, which gradually extends to the periphery; liquefaction 

 occurs slowly, so that at the end of about four weeks a thick, violet-colored 

 layer rests upon the softened and depressed surface of the culture medium; 

 at the end of three to four months the gelatin in the tube is completely 

 liquefied. Upon the surface of agar a yellowish- white, milky, thick layer 

 is formed, which commences to acquire a violet color at the end of eight to 

 ten days, and at the end of three to four weeks is seen as a wrinkled, dark- 

 violet layer with a metallic lustre, which is easily lifted entire from the sur- 

 face of the culture medium. Upon potato a dirty-yellow or olive-green layer 

 is slowly formed and gradually extends from the line of inoculation. In 

 bouillon development is very slow ; at the end of several weeks the dark- 

 brown bouillon is seen to have a violet film upon the surface and a deposit 

 of the same color at the bottom of the tube. 



275. ASCOBACILLUS CITREUS (Unna and Tommasoli). 



Found upon the surface of the body of individuals with eczema sebor- 

 rhoeicum. 



Morphology. Straight or curved bacilli, 1.3 jtt long and 0.3 1* broad, soli- 

 tary, in pairs, or in irregular groups. 



Biological Characters. An aerobic, liquefying, motile, chromogenic 

 bacillus. Produces a lemon-yellow pigment. Spore formation not observed. 

 Grows in the usual media at the room temperature slowly in gelatin, rapidly 

 upon agar and potato. Upon gelatin plates, at the end of two weeks, promi- 

 nent, opaque, yellow, punctiform colonies are developed upon the surface, 

 while the deep colonies are scarcely visible with the naked eye ; under a 

 low power they are seen to be grayish-yellow, opaque, sometimes like little 



